Substituting Carapils with left overs

Question: I have a recipe for an English I.P.A. which has 0.500 gr of Carapils but i have run out.Only grains that i have right now for substitute is Cara-Blonde and Crystal EBC 145-155. Will either of those two do or just skip Carapils and start the brew?
Answer: I'm sure you'll be fine with the cara-blonde - that's only a few shades lighter than carapils.
It really depends upon what other crystal malts are in the brew. If there are other crystals around the 20-40L, then you may not need so much of the carablonde. Then you could use 250g of that, and 250g of base malt, to avoid it becoming too sweet.
Answer: Add a reminder, the cara/crystal malts don't add any fermentable sugars, they are only for color, body and sweetness depending on the level of carmelizaton. Substituting any light cara malt should be fine.
Comment: Actually, they do add fermentable sugars, although not as fermentable as a base malt.

Substituting Carapils with left overs


UDPClient not receiving multicast data C# ASP.net

Question: Yesterday my C# ASP.net application worked great and I was receiving UDP multicast data no problems.
Today, our server was down (unknown reason), so we rebooted it.
We re-added the routes using the route ADD command (not sure how they were lost to begin with)
We see the data coming to our NIC, and the NIC sees the UDP packets information as provided by MS server 2012 Remote Access and Routing information.
However, the C# Application no longer receives any data.  The data arrives to the NIC, but doesn't seem to make it to the application.
My code is as follows for the UDP listener.
<code> UdpClient client = new UdpClient();
                IPAddress newaddress = IPAddress.Parse(anOPRA.RTMultiCastGroup[multicastCount, 0]);
                multiport = int.Parse( anOPRA.RTMultiCastGroup[multicastCount,1]);
                IPEndPoint localEp_time = new IPEndPoint(localIP, multiport);
                client.ExclusiveAddressUse = false;
                client.Client.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
                client.ExclusiveAddressUse = false;
                client.DontFragment = true;
                myDataHub.Send("BufferSize ", client.Client.ReceiveBufferSize.ToString());

                client.Client.Bind(localEp_time);
                 client.JoinMulticastGroup(newaddress);
</code>
Any ideas what could be wrong, this is so frustrating I can't figure it out.
Answer: Are you running in debug mode? If so, try running in release mode. I had the same issue (I'm using VS2012 Express) and this resolved my problem.


Restrict published SharePoint-hosted app to a single Site Collection

Question: Our SharePoint-hosted app has been published to the App Catalog successfully. Is it possible to restrict it to a single Site Collection so that nobody is able to add it to another site collections?
Answer: Approach 1 - If you are on premise.
Consider moving you site collection to a different web application and designate a separate app catalogue for the web application. This way you will be able to isolate the apps from other web applications/site collections.
Approach 2 - If you are on Office 365 or the first approach is not suitable.
Convert the add in to provider hosted add in and implement an add-in event receiver.
Implement an AppInstalling event and check before hand where the user is trying to install the add in. If it is one off the target site collection/site then allow the installation or throw a permission denied error.
To read about the add in events please refer this Create an add-in event receiver in SharePoint Add-ins
Answer: You can also try creating a app under specific site collection.Please refer blog https://docs.microsoft.com/en-us/sharepoint/dev/general-development/site-collection-app-catalog


Public nuisance in Halacha

Question: Does Halacha recognize the notion of someone being liable for "public nuisance"? In  secular law, a public nuisance is generally defined as someone who is doing something which is significantly disruptive to the rights of the public. For example, someone doesn't have to hurt someone physically to be a public nuisance by say blasting extremely loud speakers in public areas in a disruptive manner.
Answer: Rabbi Jack Abramowitz in his series called "HaShoneh Halachos" on Orthodox Union writes:

If one's neighbor has a headache and the sound of hammering would make it worse, then one may not pound grain even in one's own home so that the noise will not reach the neighbor's home and disturb him.

And

There are many other things when it comes to damages that a person
might potentially cause his neighbor, or to the public. The general
principle is that one is not permitted to do anything - even in his
own domain and all the more so in a public place - that could cause
damage to a neighbor or to passersby in the public thoroughfare unless
it's something that has become accepted for everyone to do. In such a
case, their actions are considered approved of by all the inhabitants
of the city.

With regard to noise-issues, and when people in the neighborhood are complaining about it, refer for example to Choshen Mishpat 156:2, where it says, with regard to noise and a shop:

חנות שבחצר יכולים השכנים למחות בידו ולומר לו אין אנו יכולים לישן מקול הנכנסים והיוצאים אלא עושה מלאכתו בחנותו ומוכר לשוק אבל אינם יכולים למחות בידו ולומר אין אנו יכולים לישן מקול הפטיש או מקול הריחים מאחר שכבר החזיק לעשות כן ולא מיחו בידו Regarding a shop in a courtyard, the neighbors can object and say to [the shopkeeper]: We cannot sleep owing to the noise of those coming and going, but rather he must do his work in his shop, but sell in the marketplace. But they cannot object and say: We cannot sleep owing to the noise of your hammer or the noise of your millstones, since he already acquired a chazaka to act in this manner, and they did not object.

Rav Shlomy Levy, over at Yeshivat Torat HarEtzion, summarizes:

In any event, to summarize, normal noise that is not considered exceptional is permitted, while unusual noise is forbidden. A person is permitted to raise children in his house, even if they make noise, but he cannot suddenly turn his house into a dormitory that produces substantial noise for the entire neighborhood. Certain types of nuisance are generally accepted today, but Halakha prohibits them, and so they are forbidden, such as the damage of overlooking, a foul smell, and the like.

Public nuisance in Halacha


92 honda accord overheating

Question: i replaced radiator hoses thermostat but when i started my 92 honda accord after two to three minutes the block starts getting hot the temp gauge stays at cold and no fans came on. You can squeeze the top hose and there is new coolant why is the block getting hot?
Comment: Did the new thermostat have an air bleed jiggle pin or hole in it?
Answer: Make sure you bleed all the air from the system. A trapped air pocket can cause this.
Answer: sometimes thermostats do fail. One of the symptoms is cold engine on the dashboard. I would cross check with a second thermostat.
The second thing COULD be a blown gasket since you mentioned a 92. To confirm check if your coolant level is a bit milky

92 honda accord overheating


Is it possible to burrow units to avoid damage from Psionic Storm?

Question: If there was a Psionic Storm placed down over Zerg units, could you burrow them to avoid damage? If not, do they have any kind of reduced damage for being underground?
Comment: Related question: http://gaming.stackexchange.com/questions/18961/splash-damage-to-burrowed-units-in-starcraft2
Comment: Yeah, that is similar but its not the same.
Answer: Burrowed zerg units take full damage from all sources, as burrowing only hides the unit from sight.
This includes damage from AoE abilities, like Psionic Storm or enemy Infestors' fungal growth, which don't require a target (though you probably don't want to waste energy unless you're sure something is hidden there).
Comment: Burrowed and cloaked units are visible to the player on the map. If you are looking carefully, they are easy to spot. Storms and Fungals are a pretty usual response. EMPs also reveal cloaked units temporarily, by the way.
Comment: Burrowed units also take damage from splash damage. (Was used a lot in BW to kill lurkers)


PReLU Activation Function update rule

Question: I just finished reading Delving Deep into Rectifiers paper. This paper proposes a new activation function called PReLU. Maybe it is obvious, because the paper did not mention it, but I want to know when is the parameter of a PReLU updated? Is it updated before weight update or after weight update?
Answer:
Is it updated before weight update or after weight update?

It doesn't usually matter, provided your NN framework has separate gradient calculation stage from parameter update stage.
The gradients should be collected with all weights and parameters at their current values (during back-propagation). Then the parameters are updated, using those gradients. There should be no interaction between the parameters during the update step.
However, if you have implemented the training code yourself from scratch, and have interleaved the gradient calculations and weight updates, then this only works in a pure online situation with weights updated as the gradients are calculated. In that scenario, you should probably update the weights for a layer before updating the PReLU parameter for the same layer, to prevent changes in the activation function altering the gradients during your calculations (this is not a concern with usual weight updates).
Alternatively, separate your gradient calculations from the weight update steps. This is more flexible and allows you to use other more advanced optimisations and layer designs.

PReLU Activation Function update rule


Redirect according to views filter input

Question: I have a view with two filters (country and city) on node (country) page. What I want is redirect to another node page according to user input (filter country). So if user viewing page node/uk and chooses USA in country filter and New York in city filter, drupal must redirect to page node/usa showing results for New York. View is using AJAX.
Tried using drupal_goto in views exposed form submit but this produces error Drupal.Views.Ajax.handleErrors is not a function in ajax_view.js. Help me please.
Answer: You can do it using hook_form_alter() on the exposed filter form.
It is very well explained in this post.
A drupal_goto() depending on the input entered should work.


Loading a stateGeoJSON across countries

Question: I am trying to build a chloropleth map in Javascript with zoom functionality. Map will need to have a chloropleth layer of all countries. On zooming in it will need to show a chloropleth of the next adminstrative areas across all countries. Can you please give me pointers around how do to this. How long does loading all-states GeoJSON take and how do we go about doing this.
Answer: Changing layer on zoom:
Since you did not mention what tool you will use (Google Maps, Leaflet, ...) I will try to answer your question with pseudo-code.
The principle of changing the layer when zooming is easy. You have different possibilities how to solve this.
The simplest way of doing this is by "assigning" layers to zoom levels. This could look as follows:
// Load geoJson
var country = geoJsonA;
var state = geoJsonB;
var city = geoJsonC;

// define on which zoom level
// which layer should be displayed

map.on(zoom, function() {
    if (zoomlevel < 15) {
        map.removeLayer(the other two);
        map.addLayer(country)
    } else if (zoomlevel >= 15 && < 17) {
        map.removeLayer(the other two);
        map.addLayer(state);
    } else {
        map.removeLayer(the other two);
        map.addLayer(city);
    }
});

An other approach on this would be defining bounding boxes. You would then use this bounding boxes similarly to zoom levels, e.g. if bounding box bb is outside of the viewport of the map, then show layer xy.
Loading times
I guess this strongly depends on the amount and size of the geoJsons you have. If you are planning to load all geoJson right away, then the page will need a bit of time till its ready. An approach to this might be AJAX.

Loading a stateGeoJSON across countries


django-tables2 CheckBoxColumn header

Question: How can I get django-tables2 CheckBoxColumn to honour the provided verbose_name?
If I define a CheckBoxColumn thus:
force_flag = tables.CheckBoxColumn(accessor=('force_flag'), attrs = { "th__input": {"id": "selectAllForce"}}, verbose_name='Force?', orderable=False)
the table is rendered but the column header is simply a checkbox and does not use the verbose_name.
This question has been asked previously but unless I do not fully understand the answer I cannot see that working.  Reading the suggested code, I would imagine that this would add the string 'column Name' to each row data value.
Thanks in advance for any help with this.
Answer: Looks like this is under investigation/discussion by the author of django-tables2 on GitHib

django-tables2 CheckBoxColumn header


No demand for Commercial zones

Question: None of my cities are showing any demand for commercial development. I zone them at all three levels but none ever progress. This is a recent problem after coming back to the game after a three month break - when I played before commercial zones always developed. I have even adjusted tax to low levels to try and entice shops, offices etc. Help appreciated.
Answer: According to:
http://strategywiki.org/wiki/SimCity_4/Zoning_and_Demand#Commercial
Having more neighbor connections is your best bet, as well as building up means of transportation like airports and railroads.
Otherwise, I would make sure you have a balanced demand for other zones as well. Maybe you need to increase population and/or industry.

No demand for Commercial zones


Online and Offline map areas in ArcGIS Field Maps

Question: We are using offline map areas and want to solely use offline areas in ArcGIS Field Maps. When the app has data access the option for online maps becomes available. Is there a way to remove the option of online maps so users only see offline map areas?
Answer: For both IOS and Android, you should be able to disable network access for Field Maps. By doing so, the app will only show offline areas.
For example, in Android, you can go into the app's permissions and disable network access.


How to invoke a siebel web service from a PHP web application?

Question: I am developing a Portal in which i have to pull some data from a siebel Call center application through one of the published web services. I would be glad if some body provides some code snippet for a sample application.
Answer: All web services from siebel are published with SOAP protocol, you only need to get the wsdl from siebel client application > web services > Inbound. Use it from php with php_soap client, for example. Here is an example about writting a soap client in php: php_soap client
I have samples in java, python and perl of siebel webservices invokations but, not for php. Hope it helps.
Answer: I don't know if this is even possible.  Most of the Siebel business layer access is only doable via OLE or Java object interface.  Maybe if access was exposed using an Integration service of sort you could do it, like maybe MQ or something.
I short, I have no example.  It would need to be cobbled together.  If you figure it out, Ravi, you will be paid much money.  Good luck, my friend!


Openerp Browser session logout

Question: I am using openerp web and server 5.15. Is there an way to kill the session of user when he/she closed the browser window?
If not, then is there any Javascript way then I can implement the same functionality?
Answer: I guess this has to do more with CherryPy (the Web Framework used in OpenERP) than with OpenERP itself. Try looking at this lines in openerp-web.cfg:
tools.sessions.on = True
tools.sessions.persistent = False

Openerp Browser session logout


Editing an outlook message on the iPhone

Question: It appears that when I edit a message on the iPhone send it out to someone to read in the Outlook client, they don't see my edits?  How do I fix this? We tested this a few times and seems to be occurring with all of us.
Answer: To track edits to a document, save it in OneDrive and then edit it it in Word or OneNote or Excel or Powerpoint. Outlook doesn't do revision tracking on iOS or macOS in any current 2016 or 2019 version of the suite. I don't even thing outlook web app even tracks versions, and that's where they roll out most features first now.
Then send a link to the document or just share it. We also use box and iCloud for collaborative editing to track changes and you might also consider Google if that's open for your group.


If there are 10 racers, and Racer A beats B by 0.001 seconds and B beats C by 0.002 seconds, how would you measure?

Question: If 10 athletes run a race and the winner A beats B by one tenth of a second B beats C by two tenths of a second, C Beats D by three tenths of a second etc... How would you measure whether the winner A was significantly Faster than the other racers? Could you do it without assuming at what speed the race finished? What kind of statistical test would be suitable to determine significance of a sample size?
Comment: It is not evident that a statistical test would be needed.  On that particular day in that particular race, runner $A$ was faster than $B$ was faster than $C$, etc.  Isn't that the entire point of a race?  If by "faster" you mean some generalization like "inherently faster during this race year" or something like that, then please note that one race is a sample of *one* performance for each racer.  Although you can test a sample of one for significant differences, such tests are not very powerful--which means they are unlikely to give you useful information.
Answer: It is necessary to know how the time differences are distributed and there has to be enough information to determine if an outlier is identifiable. For example, see How to identify outliers and do model diagnostics for an lme4 model?, which may give you some clues, as well as, What is the best way to identify outliers in multivariate data?
Obviously, this approach would be best to use on Boston Marathon data with many many participants with the alternative being to race the same, more limited number of participants multiple times to establish how each person performs within tighter limits than can be provided in a single experiment.


Who actually is a Post-Doctoral fellow?

Question: Many of us often talk about Bachelor's and Master's students, PhD students, researchers, professors, and postdocs.
But, do we know what we actually intend when we say "Post-Doc"?
We all know that a Post-Doc is a person who, after finishing his/her PhD, works for one or two years as a scientist in a scientific research group. Beyond this simple definition, I would like to know what you think about Post-Doc roles inside a laboratory and a group.
What is actually a Postdoc fellow?
Is he a debutant researcher? Or is he just a ultra-super-student? Or is he half a super-student, and half a researcher?
What is a Postdoctoral fellow supposed to do?
What do you expect from a Postdoctoral fellow?
Comment: In general a postdoc is someone that soon realizes he made a huge mistake about his career.
Comment: In my neck of the woods, we call debutante researchers _PhD students_.
Comment: "We all know that a Post-Doc is a person who, after finishing his/her PhD, works for one or two years as a scientist in a scientific research group."  Sorry to say: we don't even know that much.  There are many postdocs who are not scientists, and many who work for more than one to two years.
Comment: According to PhD Comics: http://www.phdcomics.com/comics.php?f=1721.
Comment: @ArtemKaznatcheev Naaaaahhh... don't think so, they're just graduated students.
Comment: Things get even more confusing if you consider [pre-doc positions](http://cstheory.stackexchange.com/q/7779/1037).
Comment: A pre-doc, in Belgium, is a post-doctoral student who is, in a sense, on probation, and needs to complete some additional courses before becoming a full-blown PhD student.
Comment: limbo: Not in student hell anymore, not in fully employed heaven either...
Answer: There are many formal roles that generally fall under the category of "post-doc":

The simplest is as a post-Ph.D researcher working with a faculty mentor and doing their own research
Some postdocs have a role as "lab manager": they help with advising students.
In addition, if given an appropriate title, a postdoc (as "visiting/research faculty") can write their own grants or collaborate on grants that might support them.
The limit of the above is a pure soft-money position that is not "supervised" by a faculty member. Such faculty are also often called 'research faculty', and may be many years away from a Ph.D
In wetlabs, a postdoc role might also be as a lab technician or lab manager, handling supplies, tech work (making knockout mice for example).
Comment: I think a post doc is also a temporary/transitory position. I know of some permanent "lab managers", with PhDs, who have no desire to write their own grants or move on. I don't consider them postdocs.
Comment: Joining @DanielE.Shub, I think `research faculty` is more or less a permanent position while `post-doc` is not.
Comment: I agree with the idea that a postdoc is, by definition, supposed to be a transient position.
Answer: In addition to Suresh's answer, I'd say that a postdoc is no longer a student. A PhD student is expected to demonstrate that she can do research, and this is sanctioned by the PhD degree. A postdoc is rather expected to demonstrate that she can be trusted with a permanent academic position.
In my field, postdoc positions usually denote fixed-term positions (between 1 and 3 years) with limited "official" administrative responsibilities (i.e. no involvement in the long-term management of the department). Most postdocs are usually funded on some project, which implies some concrete duties w.r.t. to the project (such as taking care of the "deliverables"). Some are more like "fellowships", where the applicant must come up with her own research agenda.
But there is no common basis, and it can varies greatly from one position to another.
Comment: A "fellow" the the holder of a "fellowship".  A fellowship may just be a special honor awarded to him.  Or it could come with a salary and other perks.
Answer: To quote (jokingly) a rather blunt friend of mine, a post-doctoral fellow is "someone who has a Ph.D. but is still nobody." I don't quite subscribe to so dismal a view, but it usually means someone who hasn't achieved full independence yet (inasmuch as they still have at least a nominal advisor).
I expect a postdoctoral fellow in my group to be a competent researcher who doesn't need much instruction on the basics of how to do research, but might need some training on the particular skills needed in my group. She should be capable of taking over virtually any duty in the group, and would be expected to take on some of the duties that would be associated with being a professor (or staff member in a research lab somewhere). That would mean being responsible for supervising undergraduates doing research projects, occasionally covering lectures, and being responsible for supervising the lab (purchasing equipment, and so on).
That said, the post-doctoral fellow would not be left entirely to her own devices: since she is still effectively in a training situation, she would be given help and advanced notice. I would not just surprise her with duties; they would be assigned per mutual agreement, and always with a specific purpose in mind. (In other words, I am not simply "dumping" duties on the post-doc.)
Comment: In my field, a successful PhD student is _already_ not nobody.
Comment: @JeffE: Fair enough. I don't think that it's quite so dismal. But I do think a postdoc is by definition not quite a fully established individual. I've edited my answer accordingly.
Answer: This answer is a bit different from the others. The other answers deal with what a postdoc is. My answer describes the difference between the roles of grad students and postdocs in two ways.
The first distinction is this: A graduate student is an apprentice, while a postdoc is a journeyman.
The academic system in which a student earns a doctorate and eventually becomes an academic is based on the apprenticeship system.
The graduate student is the apprentice . The graduate student is learning his or her craft from the adviser (master). The graduate student hones his or her research skills performing the research of the adviser. Completion of the PhD defense signals that the student has completed the apprenticeship.
The post-doctoral fellow is the journeyman, one who has completed training in the basic skills, but is not yet considered a master. To this end, the postdoc seeks out other masters to learn from. Since the postdoc is not an apprentice, the postdoc is given more freedom to design and implement his or her project. The postdoc is also expected to be able to work with minimal oversight from the adviser. A postdoc journeyman becomes a master upon successfully securing his or her own academic position.
The second distinction is in terms of classification and compensation. At most US institutions, the graduate student is a student. The grad student may receive a stipend and benefits, but someone pays tuition for that student. A postdoc is an employee who receives a salary and benefits. No money is paid back to the institution by (or on behalf of) the postdoc.
Comment: The two systems are related. They both came about in Western Europe in the 11th and 12th centuries. See the similarities described in these wikipedia pages: [medieval univeristy](http://en.wikipedia.org/wiki/Medieval_university) and [Guild: European History](http://en.wikipedia.org/wiki/Guild#European_history).
Comment: I like and use the apprentice, journeyman, master description I'm not sure that it is correct to say that the academic career path is *based* on the the ranking system of the old craft guilds. It is just a convenient way to describe the relationship to people outside of academia.
Answer: Thanks to the recent PhD Comics, I have a link to a pretty definitive definition
.
The NIH link is: http://grants.nih.gov/grants/funding/all_personnel_report_faq.htm#774
This links to a letter to the US National Postdoctoral Association: http://grants.nih.gov/training/Reed_Letter.pdf
Answer: At some universities, a Post-Doctoral Fellow is a different title than a Post-Doctoral Researcher due to federal regulations in the USA.
The Post-Doctoral Fellow is paid through a different funding mechanism (e.g., NRSA training grants) and is not considered an employee (thus is excluded from health insurance and retirement benefits) and is treated more like a student (may take classes or do a clinical residency; receives a non-negotiable stipend which is not ordinary income). There may be a citizenship requirement for this funding mechanism.
The Post-Doctoral Researcher is an employee (qualifies for benefits but does not take classes or receive training). It may be easier to deal with visa requirements through this position.
In both cases, postdocs do research. Neither is guaranteed to advance your career to being a professor, but pretty much everyone has to do it.
Comment: "fellow" is a status w.r.t. to an organization, "researcher" is a description of what you do. I don't see why a post-doctoral fellow isn't always a "post-doctoral research fellow" or "post-doctoral researcher fellow". But, well, I guess sometimes terms are used somewhat artificially.
Answer: A postdoc is also someone that needs to be hired by academia to do a task, that is, a contractor for academia. I am a scientific programmer, but I am hired as a postdoc because that's the only kind of contract they can give in academia. I publish no papers, have no interest in an academic career, and I have no other duties other than coding (or at least that would be the plan).
Comment: In some institutions, you'd be deemed 'research staff'
Comment: @Suresh it all boils down to the wild west academia lives in when it comes to hiring contracts. Companies trying to hire with the academic terms would be eaten alive by worker unions, but in academia this is somehow considered the norm.
Comment: In my university, you'd be "research associate" (assegnista di ricerca), not PostDoc.
Comment: Because postdocs don't get unions - they are the equivalent of migrant labor
Comment: @Suresh Postdocs ate unionized at Berkeley.
Answer:
"Whatever else they may be, postdoctorates are one of the greatest bargains in the US economy. Where else can one hire Ph.D.s, whose training and smarts put them among the best and brightest in the world, to work 60 hours a week for $30,000 to $40,000 a year, with limited benefits and little power to influence their working conditions and pay?" -- Richard Freeman, Thanks for the Great Postdoc Bargain

http://sciencecareers.sciencemag.org/career_magazine/previous_issues/articles/2002_08_30/nodoi.4149859741665864757
Comment: This does not seem to answer the question.
Comment: Interesting link.
Answer: In some cases, postdocs are seen as a means to shuffle newly-minted PhD's into "alt-ac" careers.  I just came off of one such postdoc myself.  Since the postdoc was very programming/data/technology centered, and I actually went back to school to get out of programming, it didn't really take with me.

Who actually is a Post-Doctoral fellow?


Prove EXPTIME \ NP is not a subset of NP-Hard?

Question: If we assume that NP is not equal to co-NP, how do we show that EXPTIME \ NP is not a subset of NP-Hard?
Answer: Hint: note co-NP $\subseteq$ EXPTIME, and co-NP-complete $\cap$ NP = $\emptyset$ since NP $\neq$ co-NP, it remains to prove co-NP-complete $\nsubseteq$ NP-hard.

 Further hint: if co-NP-complete $\subseteq$ NP-hard, try to show for each language $L\in$ NP, you can build a NTM deciding $\bar L$, thus NP $\subseteq$ co-NP, a contradiction.


Is caching thousands of user id's in session variables bad for performance in ASP.Net MVC?

Question: If I want to cache say 2 ids in a session variable for each user and there will be a possibility of thoussands or more users online at once, will this effect my performance of the site?
Comment: if you're thinking about **thousands** of users, then use a Server Cache (like memcache or couchbase, or even Amazon/Azure Cache systems) as you will not only use it to save the user session id, but also the data from the db...
Answer: From a memory perspective that is 2 integers (8 bytes) with 50,000 active users.  That is only 400KB.  From a speed perspective, the session is a hash table with fast lookup.  You will spend more time doing actual work than ASP.net will spend retrieving the session.
Answer: If the session state mode is InProc than there should be no negligible impact to performance. You will notice an impact to performance if you are using a session state mode of StateServer or SQLServer due to to the creation of network requests to retrieve the ids from the remote state server or sql server.
Comment: that was my big concern! So I guess it's better to hold the ids in session then fetch them from db tables? My main search page will need to know these ids and I don't want to have to fetch 2 ids from 2 tables every time the main page is searched.


Lightening of Cider

Question: My peach-apple oxidized a bit as I was juicing and started fermentation amber-brown.  Over two days of rapid fermentation with Safale US-O5 dry ale yeast, the color lightened to a pale yellow, straw color. Anyone know anything about this?
Answer: It may be that the yeast consumed all the oxygen so no more oxidation could take place. Also, the darker coloured compound have likely broken down the oxidised compounds, lightening the solution.
Answer: That's the color of yeast in suspension. When the yeast flocculate the color will go away and the cider should be clear. Also remember that when you're looking at a fermenter, you're looking through a lot more beer than you would see in a glass, so color and haze will appear more intense. The name of this phenomenon is easy to remember: Beer's Law.
When the yeast flocculate and the cider is clear, it will probably be ready to serve or bottle. Of course, check the gravity & taste to be sure there isn't too much sugar remaining.

Lightening of Cider


Differentiation and delta function

Question: Need help doing this simple differentiation.
Consider 4 d Euclidean(or Minkowskian) spacetime.
\begin{equation}
\partial_{\mu}\frac{(a-x)_\mu}{(a-x)^4}= ?
\end{equation}
where $a_\mu$ is a constant vector and the indices are summed over since one really doesn't need to bother about upper and lower indices in flat space.
Also $(a-x)^2=(a-x)_\mu(a-x)_\mu$. A simple minded calculation gives me the result $0$. But I think the answer may contain Dirac Delta function like the relation below in 3 dimension
\begin{equation}
{\bf{\nabla}} . \frac{\hat{r}}{r^2}=4\pi \delta ^3(r)
\end{equation}
A corollary question. What will be $\partial_{\mu}\frac{1}{(a-x)^2}$ ? Is it
$\frac{2(a-x)_\mu}{(a-x)^4}$ or does it also involve the Delta function?
Comment: Related: http://physics.stackexchange.com/q/9255/2451
Answer:
In a $d$-dimensional Euclidean space (with positive definite norm), one has
$$\tag{1} \vec{\nabla} \cdot \frac{\vec{r}}{r^d}
~=~{\rm Vol}(S^{d-1})~\delta^d(\vec{r}), $$
cf. the divergence theorem and arguments involving either test functions and integration by parts, or $\epsilon$-regularization, similar to methods applied in my Phys.SE answer here. In eq. (1) the ${\rm Vol}(S^{d-1})$ is the surface area of the $(d-1)$-dimensional units sphere $S^{d-1}$.
By similar arguments one may show that the identity
$$\tag{2}   \vec{\nabla}(r^{2-d}) ~=~(2-d)\frac{\vec{r}}{r^d} , \qquad d\neq 2, $$
contains no distributional contributions in $d$-dimensional Euclidean space.
For the related questions in Minkowski space, one suggestion is to introduce an $\epsilon$-regularization in the Euclidean formulation, and then perform a Wick rotation, and at the end of the calculation, let $\epsilon\to 0^+$.
Comment: Thanks Qmechanic. Writing down your equation in the index notation gives
\begin{equation}
\partial_\mu \frac{x_\mu}{x^2}=2\pi^2\delta^4(x)
\end{equation}
in 4d which is the result I wanted. Now it looks a bit silly to have asked the question in the first place.

Differentiation and delta function


Is it possible for my Sony Xperia Neo L to take other earphones besides SONY earphones

Question: My Sony earphones are damaged, I've got other earphones (non-SONY) but are not accepted by the phone. Is there a way to make them work ??
Comment: What do you mean by "not accepted"?
Answer: There are different standards for headset plugs, and Sony has started using the CTIA layout for it's smartphones since 2012. I couldn't find the official documentation on the differences, but it's pretty well explained here (In german, but the pictures speak for themselves).
The gist is, on regular headsets the order of the pins is ground-mic-right-left, but on CTIA it's mic-ground-right-left.
To get regular headsets working, you'll have to use an adapter, but if I'm understanding this correctly, headphones (that is, without a microphone) should work normally.
Answer: You can try Nokia's headphones. I think they will work with them.


Debian : 2 Nic 2 different networks switches - kernel sees a bad network

Question:
Hello

Here is the situation :
- VMplayer with 2 physical NICs (network interface cards) on the Windows host
- VM Debian 64bits
- On VM settings: both NICs are configured to replicate on the physical network
- When VM Debian is running, I declared 2 NICs :

ETH0 : 0.0.0.0 (dedicated to snort)
ETH1 : 172.22.0.12 set on dhcp (internet)

ETH0 is up and in promiscuous mode to receive mirroring flow from a switch
ETH1 is using to go to internet

I have some update scripts that must download some data from internet.
They cannot access the network, even if /etc/resolv.conf is well configured.

Depending tests that I did :
Or I can go to the net, but no capture on snort that listens eth0
Or I cannot go to the internet and snort capture eth0

What is(are) the configuration you think ?

I wish :

ETH0 : 0.0.0.0 : capture the traffic that arriving
ETH1 : dhcp : go to the internet from kernel (root) login for my scripts

Thanks for your help
Answer: You need to make sure the default route is via the eth1 interface.  For example:
route del default
route add default eth1

That will delete the existing default route (if any) and add a new default route via eth1.
You could add those as post-up commands to the definition of eth1 in /etc/network/interfaces.  e.g.
iface eth1 inet dhcp
post-up route del default || true
post-up route add default eth1

The || true ensures that the route del default never returns a failure exit code, even if there is no default route to delete.  Without that, ifup could abort before running the route add default eth1 command.
Answer: The problem came because VMPlayer needs to have a bridge nic and a nat bridge. After this, linux configuration interfaces are as usual.


Binary bayesian classification

Question: How do you construct a Bayes classifier for a binary target where it is assumed: $p(y=1)=\alpha$ and $p(x|y)$ both multivariate gaussian?
Comment: This does not make sense.
Comment: I vote to re-open this question. It is not well-phrased, but I interpret it as  asking for a decision rule to decide between two hypotheses: $Y=1$ and $Y=0$ with prior probabilities $\alpha$ and $1-\alpha$ respectively, based on the observation $X$ where the conditional distribution of $X$ given $Y$ is a multivariate Gaussian distribution, both for $Y=1$ and $Y=0$. The decision rule is, of course, easy to state, but implementation is messy. The case when $X$ is bivariate Gaussian under both hypotheses is discussed in my answer to [this question](https://stats.stackexchange.com/q/18316/6633)
Comment: What do you mean that "... a and p(x|y) both multivariate gaussian"? a seems like a scalar. Do you mean that you want a normal *prior* for a? What do you mean by "multivariate"? You seem to have only 2 variables. Etc.
Answer:
Assumption: I assume that this question is asking for the Bayes classifier given that $Y$ is a Bernoulli random variable with parameter $\alpha$ and the conditional distributions of the observation $X$ are multivariate Gaussian distributions.

If both conditional distributions of $X$ given $Y$ are non-degenerate
multivariate Gaussian distributions, that is, they possess densities  $f_i(x) = f_{X\mid Y=i}(x\mid Y=i), i = 0, 1$,
then the Bayes classifier can be expressed as
$$\frac{\alpha}{1-\alpha}\cdot \frac{f_1(x)}{f_0(x)}~~\begin{array}{c}\hat Y=1\\\gtrless\\\hat Y=0\end{array}~~ 1.$$
The decision boundary can also be stated as the hypersurface defined by the equation
$${\alpha}\cdot{f_1(x)} - {1-\alpha}\cdot{f_0(x)} = 0$$
which does not have a simple solution in general. The two-dimensional case is treated in this question where the hypersurface is found to be a conic section.

Binary bayesian classification


How to add excel tables with colors into overleaf?

Question: I have this timeline made using Excel and I was wondering if there is an easy to transfer this into Overleaf -
Comment: Although this does not directly answer the question on how to transfer a table from excel to latex, you may want to take a look at https://tex.stackexchange.com/a/579761/134144
Answer: Excel2Latex may work for you, but I was unable to get it working in my copy of Excel on the Mac (I have Office 365 and version 16.49 of Excel). It hasn't been updated in four years so you may have better luck with an older version of Excel.
The documentation is a little outdated. The options aren't in the Tools menu but, at least on my Mac, it's in the ribbon under Add-ins. The interface gets a little confused with my retina mac display (it seems to want to render things really small), but it does appear to work. By default, it assumes the booktabs package is loaded but this can be configured.


Connecting Bluetooth module to arduino

Question: I have a RN 41 (Roving networks) bluetooth module, have no breakout board, want to connect it to Arduino duemilanove, can anyone please help with the circuit diagram and the components required to connect module to arduino
Comment: What do you want that's not on the typical application circuit of page 4 of the datasheet? (see http://www.rovingnetworks.com/documents/RN-41.pdf )
Answer: Consider using a prototype shield with the module mounted "dead bug" style (upside down - in this case with the RF cover on the prototype grid). Use hot glue or double sided tape to secure it. Then, solder wires from the Bluetooth module pads to the Arduino shield pins.
Note that you can mount the module at the end, to give the required RF keepout clearance the datasheet calls out.

Connecting Bluetooth module to arduino


QGIS Helmert transformation plug-in: "Missing metadata file" error

Question: I want to convert the integer coordinates with the x and y coordinates to the coordinates of ED50. When I install the QGIS 2dhelmert plug-in, I get a 'missing metadata file' error. How do I solve this problem? Is there another method?
Comment: For plugins related errors please file an issue report on the plugin author repository which is visible when you install or search for the plugin
Answer: As far as I can see from https://plugins.qgis.org/plugins/helmert2d/ , the plugin was designed for QGIS 1.7.
Since then, the plugin API of QGIS has changed a lot, and the plugin will not work in QGIS 2 or QGIS 3.
Apart from that, you don't need Helmert 2D for converting coordinates to ED50. Just use Save As ... and specify the CRS of the target file.


Debugging Responsive File Manager Plugin (TinyMCE)

Question: Yesterday I found this great looking plugin for file and image management for tinymce however I cannot get the files to actually save to the drive. I have tried every commbination I can think of.
responsivefilemanager.com - This plugin.
Anyone used it before and know of the settings I might need?
The plugin sits here: /public_html/cms/app/webroot/js/tinymce/plugins/filemanager
I'm trying to set it up so the uploads go here: /public_html/cms/app/webroot/files/cms
The config file for the plugin has 3 lines to configure for this, these are as follows and as I have set them up:
<code>$base_url="http://domain.com/cms/";  // base url of site. If you prefer relative urls leave empty
$upload_dir = 'app/webroot/files/cms/'; // path from base_url to base of upload folder
$current_path = '../../../files/cms/'; // relative path from filemanager folder to upload folder
</code>
Now when I started working this out I would get an error for the plugin saying the root folder doesn't exist so I keep playing with the paths and now I don't get this error but I still cannnot get it to upload the images, everything looks like it works, I get the preview as the image is uploading and a green tick once it's complete then I go back to the files list and the image isn't there. It's not on the server either. I'm wondering if there is a way to debug this and work out what's happening?
Thanks
Comment: Hi, I use this plugin but I get this error "The path is not writable" the folder is already 777, have you any idea why is this happening?
Answer: I ended up getting this to work with the following settings:
<code>$base_url="http://domain.com";  // base url of site.

$upload_dir = '/cms/app/webroot/files/cms/'; // path from base_url to base of upload folder

$current_path = '../../../../files/cms/'; // relative path from filemanager folder to upload folder
</code>
Thanks
Answer: Try the following settings if you still have not got this sorted out yet:
$base_url="http://www.domain.com/cms";  // base url of site. If you prefer relative urls leave empty --> No trailing slash
// The upload directory will be a dir you have created for the files to be uploaded to, ie: localhost/cms/app/webroot/files/cms --> this file must have write permission.
$upload_dir = '/app/webroot/files/cms/'; // path from base_url to base of upload folder --> write permission (chmod = 755)
$current_path = '../../../../files/cms/'; // relative path from filemanager folder to upload folder (you are missing one "../")
// The thumbs folder located in tinymce/plugins/filemanager/thumbs must also have write permission (chmod = 755)
That should do it
Comment: Thanks, I will try this later when I am near the code again and let you know. Thanks for your reply.
Comment: Thanks I just tried these settings and I get this error in the popup: There is an error! The root folder not exist.
Answer: use gsynuhimgupload plugin TinyMCE
http://gsynuh.com/tinymce-simple-image-uploader/136
TinyMCE simple image uploader
Here's a repost of my TinyMCE image uploader plugin. It used to be on gsynuh-labs.com (but I let this domain go).
please note that this plugin is no longer supported by me – and I'm not responsible for any inconvenience caused by it, it is shared "as-is" and you have to be responsible when using it ie: take care of any possible injection problems/security problems in your own site's context.
I'm not interested in expanding it myself as I was only looking for a very minimal image uploading plugin for myself but If you are going to expand on it, I can list your version on this page if you want, just contact me.
—


What is the minimum padding or margin between adsense content and navigation bar?

Question: I am working on my website and I want to put adsense on the webpage. I am not sure how close is too close between adsense content and my navigation bar?
Comment: Are you looking for some kind of actual requirement from Google? (I don't think there is one other than avoiding confusion between ads and content.) Or for some kind of subjective evaluation?
Comment: Avoid confusion is very abstract. Almost everyone suggest put the ads color as website background color. This is definitely a confusion, isn't it?
Comment: You didn't actually answer my question. Though the point of it is that there likely isn't an answer to *yours*. Are you looking for a specific minimum distance to keep your ads away, or something? That's just not going to happen.
Answer: There is no fixed spacing requirement other than the above mentioned "can't lead to confusion". The only notable exception to this is that AdSense placement must be a minimum of 150 pixels away from any flash games and this is to avoid accidental ad clicks from users frantically clicking around a flash game.
A good rule of thumb I have used in the past when placing AdSense ads is to use a 20 pixel margin on the sides between the content and the ad block and at least one blank line (

) above and below. By following these rules of thumb I have never had any issues with ads being considered too close to content by Google and it has the added benefit of providing sufficient space to identify the ad block as not being part of the page content while at the same time not being such a large spacing as to waste a significant amount of screen real estate.


Is it possible to use the GoPro camera when it is connected to a pc/notebook with a USB Cable?

Question: I have Hero3+ Black Edition.
For now I cannot shoot or even configure the camera when it is connected to a notebook with a USB Cable.
When I connect my camera to a notebook with a USB Cable, a charging battery icon and a USB icon appear on a camera screen. Both buttons do nothing, are inactive (Shutter/Select Button and Power/Mode Button). Only Wi-Fi On/Off Button works. In addition, it is not possible to configure the camera with GoPro phone app – setting icons are disabled. Moreover, the phone app does not even show a current picture from the camera when the camera is connected with USB Cable (I use GoPro Android app on Google Nexus 5).
My question is: is it possible to use a camera when it is connected to pc/notebook with a USB cable? Is it somewhere configurable in the camera?
My goal is: I want to shoot and immediately see the result on a screen of my notebook. At least from MicroSD card. For now I make a picture or video, turn the camera off, take out MicroSD card, put it into a notebook and only now have a possibility to see the result. It is cumbersome.
Comment: You can do it using the Hero 3's built in WiFi. You are looking for _tethering_: the search for a solution is hampered by the fact that the word tethering also applies to physically attaching the camera somewhere. Anyway, I found this, hope it helps: http://www.richardharrington.com/blog/2014/1/23/shooting-with-a-gopro
Comment: GoPro livestreaming tutorial can be found here: https://goo.gl/L5y91D
Comment: For a single extended recording, you can start the recording and then plug in the USB cord to supply power from the PC.
Answer: No, the GoPro cannot be controlled over a USB connection.
If the GoPro is plugged into a computer and switched on, it will go into USB mode. This lets you download photos and videos from the camera. But you cannot take photos or video in this mode.
For the Hero3 or Hero3+ (or older models with a wifi Bacpac) they can be controlled over wifi. There are GoPro apps for Android and iOS or Windows Phone. There isn't any official GoPro software for controlling from a PC, though there are several options, eg:

WiGo from Cam-Do (Windows)
HeroProApp from KonradIT (windows, Linux, MacOS)
GoPro Commander (Windows 8)

Or the GoPro essentially works as a web server, so you can just connect and control it with a web browser. So these would let you control the camera from a PC, and get a preview image, and download photos etc over the wifi.
Comment: Here's a great reference for using the GoPro as a server: https://github.com/KonradIT/goprowifihack
Answer: As of July 2020, GoPro released a beta firmware that supports webcam mode (only on HERO8 Black). Your computer detects the camera as a webcam in this case and you can use it with existing tools that support webcam capture.
How to Use HERO8 Black as a Webcam explains this in more detail.
Answer: Not sure about shooting Video, but to capture the image from the GoPro Hero4 Black, we can now put it in WiFi Mode and connect to the computer that way.. There is a software application in BETA that was recently released that lets you capture the image, store it and makes a timelapse..  Pretty slick considering the awesome resolution of the GoPro   :)       Check out my link to the test:   http://www.dahlonegaweather.com/snapshot1.jpg


How did Archimedes's water clock work?

Question: I read that several principles of Al-Jazari's monumental water clocks were based upon earlier designs of water clocks by Archimedes, for example the use of valves, feedback system and flow control regulator. Apparently, Archimedes even wrote a treatise On the Construction of Water Clocks. So what innovations did Archimedes introduce in his hydraulic clock?
Comment: The short answer: it is not known. A treatise of Archimedes if he wrote one, did not survive. There is no descriptions of clocks made by Archimedes, if he made any. The rest is useless speculation
Answer: Jazari is referring to "an Arabic treatise of unknown date and authorship" that describes a monumental water-clock. It is not listed among Archimedes's works in any ancient sources, and according to  Hill, most of it was written by several Arabic authors. The "author" is now referred to as Pseudo-Archimedes. Ridwan al-Saati built Jayrun water clock based on the Pseudo-Archimedes's design. He also mentions some Hormuz, who invented a water clock used by his father in the construction of the Damascus clock:"the design continued in the land of Fars for a long time, and was transmitted from there to the land of the Greeks, and its construction spread out in the land until it was transmitted to Damascus, where it was constructed up to the days of the Byzantines and after that in the days of Banu Umayya, according to what is mentioned in the histories". For details see Hill's Arabic Water Clocks,
It is known that a public water clock was erected in Gaza in fifth century AD, so Hormuz might have lived before the rise of Islam, and possibly re-invented the water clock independently. But simple water clocks were already used by ancient Babylonians and Egyptians. A perfected version, clepsydra ("water thief") is due to Archimedes's contemporary Ctesibius (c.285-222 BC), a renowned engineer, the founder of pneumatics, and possibly the first head of the Alexandrian Museum. Unfortunately, none of his works survived to our times, but his inventions are described by Vitruvius, Athenaeus, Philo of Byzantium, Hero and Proclus. A detailed analysis of Ctesibius's work is given in Russo's Forgotten Revolution.
Some modern engineers credit clepsydra as the first automatic feedback device.
The problem Ctesibius faced was that the speed of water escaping a container through a hole depends on the water level in it. To make it work for keeping time he needed a container where the water level remains fixed. This is accomplished by a float with a valve that blocks the inflow when the level rises, and lets it through when it falls, a feedback controller in modern terms. The clock involves three containers, the first one serves as a water reservoir, and empties into the second, which has the float with a valve ensuring that its water level remains constant. So the speed at which it empties into the third container is also constant, and a float in the third container will rise uniformly. A pointer attached to it indicates time. See a nice illustration at Lahanas's site.
Comment: So how did this automatic feedback device work? I want to understand how it's possible to regulate the flow of water. And by the way, i'm not sure that archimedes didn't contribute to the design of water clocks. Many reference credit him with at least a less perfected clepsydra than ctesibius's, while some credit him with designing another kind of clepsydra. At least he was the first inventor of a feedback system.
Comment: @user2554 See edit. The references you mention all have Pseudo-Archimedes's treatise as the source. If Archimedes's work on water clocks existed in antiquity it is likely that Vitruvius, Hero, etc. would have mentioned it along with Ctesibius's.
Comment: Sounds like the feedback system is an early version of the mechanism in a toilet cistern. Anyone with a leaky toilet which constantly dribbles water into the pan has a Ctesibius water clock.
Comment: Perhaps i should change my question - my question is - what are the ideas behind the complicated historical water clocks. According to wikipedia, modern versions of the historical water clock rely on the principle of the syphon. So i ask how to translate it to the mechanical language.In particular, i'm interested to know the inner-workings of al-jazary's "castle clock", which is an early example of programmable analog computer.
Comment: @user2554 It would be better to ask a new question since it is quite different from this one. Also, a question on detailed inner workings might be a better fit for Engineering SE with a history tag http://engineering.stackexchange.com/questions/tagged/engineering-history since this sight focuses on history. But it really depends on the level of detail and where the focus of the question is.
Answer: al-Jazari (and Ridwan too) explicitly says that Archimedes is the source for several of the components of his clock(s); he also says that one component of Archimedes' clock (the flow regulator) does not work, and proposes a solution where the regulator is a full circle rather than a semi-circle.
The Arab treatise on the construction of water clocks that is attributed to Archimedes describes a clock that is very similar, from a mechanical, pneumatic and hydraulic point of view, to al-Jazari's and Ridwan's clocks, so it is very probable that both those engineers based their own designs on this treatise (or on the tradition it is based onto).
Scholars such as Hill believe that the work might have been originally written in Greek, but that the treatise was heavily reworked by Islamic authors; others, such as Drachmann, believe that it might be a compilation of several Greek authors.
More recently, Anette Schomberg recognised the treaty as (mostly) a translation of a treatise on water clocks by Philo of Byzantium; the clock described by Philo, therefore, should be imaged as similar to the Gaza clock described by Procopius, or the water clock described by Cassiodorus, which later were adopted by the Islamic engineers (see al-Jazari Castle clock for a very similar example).
Furthermore, Schomberg recognizes both the clock and the flow regulator in the description of Ctesibius' clock written by Vitruvius: this flow regulator is the same as that described by al-Jazari, so the basic idea should be:

Philo of Byzantium invents a water clock based on a floater sinking in a vessel that provides the motion for several mechanical, hydraulic and pneumatic automata (including the hour indication). Philo's flow regulator is semi-circular
Ctesibius improves Philo's clock on a couple of points, including a circular flow regulator
This clock is know to Vitruvius and some implementations are known to other authors (Procopius of Gaza, Cassiodorus and Boethisu, maybe Teophanes)
Arab authors translate a treatise that describes Philo's clock (including the semi-circular flow regulator)
al-Jazari and Ridwan receive this tradition and build several clocks on the same principles; they either receive the tradition that links directly back to Philo (maybe the same Arab treatise we have), and re-invent the circular flow regulator, or they receive Ctesibius' tradition and present this innovation as their own (the second possibility has a higher probability, due to the presence of another of Ctesibius' improvements into al-Jazari's and Ridwan's clocks)

So to sum it up:

What were Archimedes' innovations to the water clock?
Probably none, he did not build any as far as we know.
What were Philo's innovations to the water clock?
He probably built the original one, with all the automata and the sounds, and also wrote the treatise that is currently attributed to pseudo-Archimedes.
What were Ctesibius' innovations to the water clock?
He definitely produced a better outflow device (Vitruvius explicitly says so) and he probably invented the circular flow regulator. "Ctesibius clock" was, in any major sense, similar to al-Jazari's Castle clock
How did the flow regulator work?
It was composed by two parts, one to make the inflow to the tank regular (through a cone-shaped floater that matches a cone-shaped spout) and one to make it vary with the day of the year (the semi-circular/circular stuff I mentioned above)
What about the syphon in Ctesibius' clock?
Very probably never existed, it was probably due to the imagination of Perrault, who produced a lavish and accurate edition of Vitruvius' in the 17th century, but proposed the wrong reconstruction for Ctesibius' clock

Source:  Schomberg, A. (2017): "To amaze the world" - A contribution to the shape and mean-ing of the water clock in antiquity. In: Wellbrock, K. (ed.): Schriften der Deutschen Wasserhistorischen Gesellschaft, Band 27-1, Siegburg, 2017, 301-340. (you can find it on academia.edu)

How did Archimedes's water clock work?


How do I delete empty NLA tracks and why are they so randomly created?`

Question: I can't seem to delete unwanted tracks when I have the "Include Missing NLA" button selected. What bothers me more is it seems to create tracks by random.  In the screen shot below, 1/4 lights have an NLA track, my camera has an NLA track, the Mesh Body that is attached to my Armature has an NLA track and the armature itself has an NLA track.  Also the eyeballs have one. This seems very random, where do these tracks come from? Why are they so random?  Is it possible to clean them up?
Answer: You must have given an action to these objects at one point. But to remove all the useless tracks, right click and Remove Empty Animation Data:

You can also activate the Only Show Selected option, which will allow you to only see the track of the selected object(s):
Comment: This method doesn't work.  It literally empties the animation data, but the "eyeball" and the "Body" objects with empty tracks are still there.
Comment: Please share your file (remove all the useless objects): https://blend-exchange.com/


Interpret results from Johansen (cointegration) test

Question: I have 3 variables ( GDP, exportation, industrial production). i found that variables are not stationary in level but stationary in their first difference. I made the Johansen test, I must choose between the five models. That's why i made the test which summarise all tests.  The appropriate model is chosen according to the information criteria. The problem that I can't make an interpretation for the result that i have.
Answer: What are your variables? I would usually go with AIC. In this case, it shows that the most unrealistic specification is the most appropriate for your data. However, I think you should decided what to choose by first testing for unit roots and then only use either the 3rd (i.e.Linear trend, intercept and no trend) or the 4th (i.e.Linear trend, intercept and trend) specification above.
If your data is trend stationary and some are unit root, I would recommend considering the 4th specification.


Is Comptia's Project+ certification respected/respectable?

Question: What do people think of this certification? Is it something to advertise if you have it?
Answer: It depends on how you define respected. If you mean on par with a PMP or Prince2, then no, it's not on that level. Not because there's anything inherently 'wrong' with it, but simply because it's not as rigorous as the others, and the requirements to sit of it aren't as stringent.
Think of it as a 'very' entry-level certification. But if you have it, there's certainly no reason not to advertise it.


Need help using Touchegg with Ubuntu Gnome 15.04

Question: I have installed Touchegg using
sudo apt-get install touchegg

I created the configuration file using
mkdir ~/.config/touchegg
gedit ~/.config/touchegg/touchegg.conf

and created a gesture to go back on webpages:
<gesture type="DRAG" fingers="3" direction="ALL">
        <action type="MOUSE_CLICK">BUTTON=8</action>
    </gesture>

Nothing is happening when I perform a 3 finger gesture in Chrome.  I understand that Touchegg cannot be used with Unity, but I haven't seen anything regarding compatibility problems with Gnome 3.14.
Any help would be greatly appreciated
Answer: Is it only for 3 finger and less gestures? if so, it may be because synaptics is using them, try
synclient TapButton3=0 && synclient ClickFinger3=0

that will disable 3 finger actions from synaptics and use touchegg's actions. Similarly by disabling 2finger scroll and tap, you can get touchegg's 2 finger pinch to work (along with touchegg's inferior 2 finger scroll).
Answer: This works on Ubuntu 15.10;
Create a .xprofile file in ~ with:
synclient ClickFinger3=0
synclient TapButton3=0
touchegg &

Reboot and Touchegg works.


Why is master-slave replication in mongoDB deprecated? How is a replica set better?

Question: What are reasons to choose a replica set over master-slave replication?
Answer: In addition to providing all the functionality of master-slave deployments, replica sets are also more robust for production use.
Master-slave replication preceded replica sets and made it possible to have a large number of non-master (i.e. slave) nodes, as well as to restrict replicated operations to only a single database; however, master-slave replication provides less redundancy and does not automate fail over.
Answer: Question 1: Why you should use replica set over master-slave replication?
Answer: A) Automated handling of failures - In situations where the master node has failed in the Master-Slave replication you would have to perform manual actions like connecting to one of the slaves and restart it as a master.  Replica-set provides this out of the box and one of the secondaries will be automatically elected as a new primary.
B) Automated Recovery - In the Master-Slave replication the oplog exist only on the master so in case of failures you would have to re-create it on the new master and then sync all other slaves to it.
Replica-set handle oplogs differently and save you this extra administration effort.

Question 2: When to use each one of the deployment strategies?
Answer:
When you can.
Replica-Set can be considered as the next-generation of Master-Slave strategy so it should provide you with all the capabilities that the old Master-Slave architecture gave.
With addition to that, since MongoDB 3.6 master-slave replication is deprecated.
The only situation where I can think of that Master-Slave is preferred (beside when running on legacy systems) is when you have more then 50 replica nodes in the architecture - This is the top limit of Replica Set at least as mentioned here.


Are we losing reviewers or getting extra new users?

Question: Back before June 2017 and earlier, I rarely saw the FP queue exceeding 10. But since August, I've been rarely seeing it falling under 15, sometimes growing to 60. The same is for the LQP when it has grown from 5 to 15.
Comment: The FP queue was actually in the hundreds for a long time before that -- IIRC, it was mostly a specific effort from me and Izzy that brought it to 0 initially.  I definitely haven't had time to focus on it recently.
Answer: Thanks for raising this issue. To simply answer this, I would like to attribute this to time availability. There is a fair number of users with reviewing privileges for first posts (500+ rep users ≈ 430) and much less for other review queues.
Some of these users of late have not been active on the site, to perform various duties as reviewing (myself included) due to time constraints, however occasionally find time to carry out the duties wherever possible.
In conclusion there is a growing number of new users (which is good) but it's not necessary that reviewers are declining in number, only time constraints. I think other users can give more reasons why review queues are retaining lots of posts than before.
Comment: Another thing I forgot to mention is that, tbh I  thought to give others a chance to review once I hit the 1000 mark :)
Comment: Why am I seeing 430 instead of 784?
Comment: @ibug fixed thanks
Answer: I had been an active reviewer of all queues including the First Posts, and I currently top the First Posts review stats at 5436 posts reviewed. In the past I always clear the queue (or use up the daily 20 limit), but starting last month I personally no longer visit the First Posts queue. 3 reasons:

It's too time-consuming, since there's almost always a full queue everyday.
The queue is heavily mixed in type and quality, whereas the posts in Close Votes and LQ Posts are almost always in need of action, and both those queues have a unified pattern of action, making it easier to go through.
Since flagging a post as non-answer or low quality would push it to the LQ queue at a later time, often I end up processing the same post twice.
Comment: Good. For exactly the same reason I like other queues more than FP/LA.


Baking bread during the day

Question: Why is it that bread made during the day is lighter than bread made in the early morning
Comment: Most likely thing is that your room is warmer.
Comment: @derobert That should be an answer. It makes sense.
Comment: @Jolenealaska Yeah, I probably should have posted it as an answer, but now rfusca has beaten me too it.
Answer: All other factors - ambient temperature, humidity, oven temp, etc - accounted for, the specific time of the day doesn't make any difference, whatsoever.
But alas, this is the real world, we don't hold other factors constant.  Most likely your room is slightly warmer and potentially your room could be a bit more humid in the afternoon.  These could lead to a more risen product if unaccounted for.  But overall, its not the time of the day.

One caveat- There does appear to be some (and by some, I mean a single published paper that I can locate) evidence to suppose circadian cycles in yeast.  This would indicate a faster growth rate in the day.  But the evidence is underwhelming currently and is almost certainly overpowered by other environmental conditions if present at all.

Baking bread during the day


Why don't my radio triggers work even when I've set the flash to slave mode?

Question: Hello hope someone can help. Any clue why my Godox CT16 triggers don't seem to be working? The sales description say it's compatible with my camera. I'm using new batteries. The triggers communicate fine with each other (doesn't flash even though the triggers communicate with each other). I've set them on the same channel, my Canon EX 430 II's slave mode is turned on. Tried e-TTL and manual mode as well, I know it works for sure as I saw someone post a YouTube video showing the same trigger and a similar flash (Canon EX430).
Answer: The issue here is that you set the 430EX II to slave mode.  You need to set up the flash so that it thinks it's on a camera hotshoe (i.e., take it out of slave mode).
The wireless modes in the 430EX II are only for Canon's "smart" optical wireless system. Putting the 430EX II into slave mode is telling it to ignore signals on its foot (where the radio trigger is) and to only "listen" to the sensor under the red panel on the front. The CT16 Tx/Rx are faking being a flash foot (transmitter on the camera) and a camera hotshoe (receiver on the flash's foot) to get remote firing.
Similarly, if you have any wireless flash settings set in the camera menus? Those won't work. You need to set the camera as if it were using a flash on-camera. The CT16s are manual single-pin triggers (that's why they're "compatible" with multiple camera brands), so they don't speak "Canon" (or "Nikon" or any other specific brand communication). You can't use them for TTL, HSS, or remote power control.
Some TTL radio triggers, like, say, using a Godox X1R-C receiver with an XPro-C transmitter would let you use the camera menu wireless flash settings to remotely control the 430EX II, but this is relatively unique to Canon (whose flash system is apparently either the easiest or most popular target for Chinese 3rd party companies to reverse engineer) and often won't work for other camera brands.

Addendum from comments:

Can[not] use flash menu for external settings. Says incompatible flash or flash power off.

Yes. The CT-16 are single-pin manual triggers. They cannot talk to the camera's flash control menus. That requires the four other pins and electronics to talk to the camera that it doesn't have.

Took apart the receiver to try to connect flash single bottom pin and receiver pin. This works when I do that but still doesn't work when I press the trigger. Trigger and receiver communication good both on and off camera.

This puzzles me. I see no earthly reason why you'd do this, and you may have broken the receiver by disassembling it, given your later reports of having to apply pressure at an angle to get things to work. If you want to test whether something works properly for sync, simply shorting the sync signal to ground with a piece of wire should do it.  On a hotshoe, it's the center contact that's sync and the rails that are ground; on a flash/transmitter foot, it's the center pin that's sync and the contact for the rails that's ground.
Don't do this with a vintage (pre-digital) speedlight though, unless you've measured the sync voltage as safe. With some older flashes, you could get zapped with >250V doing this.

Tried to fit the shoe backwards on flash to match the bottom pins.

If the pins match the contacts, that's not backwards, that's the correct orientation. :D  You may have initially had the trigger on backwards, which is why it wouldn't fire.

footenote: the Godox CT16 triggers are incompatible with Godox's Godox 2.4 GHz system because they're 433 MHz. But the FC16 triggers, despite being 2.4 GHz, are also incompatible with the X system gear. Bandwidth is not the same as communication protocol.
Comment: Thank you for the detailed reply. I wrote a detailed reply back but lost it due to writing to much, . I will try again to explain. Someone on canon forum explained about the slave mode so currently I'm on manual mode for the flash. Manual mode on canon 100d . Can use flash menu for external settings. Says incompatible flash or flash power off. Took apart the receiver to try to connect flash single bottom pin and receiver pin. This works when I do that but still doesn't work when I press the trigger. Trigger and receiver communication good both on and off camera.
Comment: Tried to fit the shoe backwards on flash to match the bottom pins. No luck. If I try to angle touch the pins than it flashes.
Comment: Wish I can upload cpl photos to show you. If you have telegram @myim74 appreciate the help  thank you
Comment: Holy cow it's working. But i literally have to have the side of the receiver half opened in a angle there must be a bad connection somewhere. Will keep trying. Thank you
Comment: Got it to work. It's a bad connection I have to press down the on flash into the shoe and hold it for it to work, wow. Will try to figure out how to keep the good connection. Thanks for you help
Comment: @Mark, you can [edit your question](https://photo.stackexchange.com/posts/128761/edit) to add additional information. Think of comments not as a messageboard discussion, but as footnotes that can be deleted at any time. ;)


How can client update transaction after taking snapshot of Mithril?

Question: According to what I read in the Mithril docs. The snapshots will be saved in Mithril Aggreagtor for each epoch (This means 1 snapshot will be created every 5 days). Light wallets can then download this snapshot to see their transaction history without downloading the full node.
But snapshots only provide pre-snapshot transaction information. If after the snapshot is created, I make a transaction, will the transaction be updated on my wallet? Or do I have to wait 5 days for the next snapshot of my transaction to be updated?
Answer: A mithril snapshot currently contains the whole persisted DB of a cardano-node. As said by @roy-nakakawa, it's tied to a Cardano epoch because Mithril relies on the epoch's stake distribution for signing the snapshot, but there won't be a single snapshot per epoch. It's still a parameter to be tuned but the idea is to balance the resources needed to produce signatures, aggregate them and build snapshot with the amount of work needed to catch-up in between snapshots, to decide on the frequency of snapshot generation.
To address your questions:

If after the snapshot is created, I make a transaction, will the transaction be updated on my wallet?

It would depend on the specifics of your wallet, but the idea is that a (heavyweight at least) wallet would start with a snapshot taken at some point in the past, and then "follow the chain" from that point on, a process that should be pretty fast (eg. seconds or minutes) to reach the tip of the chain.
Once there, it will proceed as normal and your transaction will certainly be reflected in your wallet's state and on-chain as soon as possible, eg. pending confirmation.

Or do I have to wait 5 days for the next snapshot of my transaction to be updated?

It's not clear what you mean by "next snapshot of my transaction" but no, you won't have to wait for 5 days as your wallet will have caught up before.
What I have said is true for the current state of Mithril which is geared towards heavyweight wallet as we are still figuring out how to best fulfil lightwallet's needs. A light wallet does not have direct access to a cardano-node and relies on a third party to provide a trusted view of the chain, and the current idea we are exploring is to find a way to provide a fragment of the snapshotted state, and/or sign multiple things.
Comment: What is the mechanism of heavyweight wallet follow the chain after taking snapshot? You mean we have to rely on another sever?
Comment: Sorry for taking so long to respond @QuangDaniel. The snapshot is used to prime a Cardano-node, then after it's bootstrapped, it follows the chain normally, connecting to other nodes in the network and pulling new blocks as they are diffused across it.
Answer: Mithril snapshots will be generated more often than Cardano epochs.
Comment: How often? What if I make a transaction 1s after snapshot?


Where does the potential energy come from for a charge?

Question: The potential energy of a charge which is brought near another charge (of the same sign) from infinity by applying an external force which is equal to the electrostatic force of repulsion. The potential energy has an inverse dependence with distance. Therefore, the potential energy increases as we bring the charge closer. But where is this energy coming from? Since the work done by the external force is equal to the negative work done by the electrostatic force. Only way I can explain is the kinetic energy decreases as the charge becomes closer and potential energy increases, keeping the total energy constant. Am I correct or is there is some other explanation?
Comment: Then where does the potential energy  come from? Isn't the total energy supposed to be conserved?
Comment: From the external force. The external force just balances the electrostatic force, we assume that we are moving the particle at zero speed or "very slowly"
Comment: @Bob D, deleted to address this.
Comment: @aditya_stack OK I deleted mine as well
Answer: The only requirement is that there is no change in kinetic energy of the charge when moving between the two points. This can be accomplished by having the external force equal the electric field force so that the velocity of the charge is constant between the two points.
If the charge begins at rest, then the external force may need to be briefly greater than the force of the electric field to get the charge moving and briefly less than the force of the field just prior reaching the second point to bring it back to rest, for a zero net charge in kinetic energy.
The gravitational analogy is lifting an object a certain height beginning and ending at rest
As far as where the potential energy comes from, it ultimately comes from the external agent. It does positive work giving energy to the charge and the field does an equal amount of negative work taking the energy given to the charge by the external agent and storing it as electrical potential energy in the charge/electric  field system.
Hope this helps.
Answer: The work done by the external force on the charge increases its potential energy.
Comment: 1. Where does this potential energy come from? and 2. What about the work done by the electrostatic force?


SQLite query using CursorLoader

Question: I am trying to get unique column values in my loader. My code is like this :-
public Loader onCreateLoader(int id, Bundle args) {
    if (mSelectedSpinnerOption == 1) {
        return new CursorLoader(this, Suggestion.CONTENT_URI, Suggestion.PROJECTION,
                BadBehaviourColumns.PACKAGENAME="DISTINCT", null, BadBehaviourColumns.TIMESTAMP + " ASC ");
    }

}

I want all the values with distinct package name values. How do i achieve this using the above code?
Answer: I am writing this answer because I faced the exact same issue while querying with CursorLoader and all I got were the answers related to database.query().
There is a simple trick which can be used something on the lines of SQL injection. Instead of using DISTINCT, here GROUP BY has been used which works faster unless you are low on memory (Ref: Huge performance difference when using group by vs distinct).
Following is the query you have to execute to get distinct column1 items from table_name.
SELECT column1 FROM table_name GROUP BY column1;

With this technique the query you end up executing.
SELECT column1 FROM table_name where (column1 NOT NULL) GROUP BY (column1);

Following is the implementation in android.
String selection = "(" + column1 + " NOT NULL) GROUP BY (" + column1 + ")";
CursorLoader c =  new CursorLoader(this, uri, projection,
            selection, null, null);

Answer: Just hacked this out myself, and yes it is very much an SQL injection. However, it does work so long as you manage to get the resulting (generated) SQL to end up correct. Check out this example:
Cursor c_buckets = getContext().getContentResolver().query(baseUri,
     new String[]{PhotoContract.ThumbEntry.COLUMN_BUCKET_NAME,
                  PhotoContract.ThumbEntry.COLUMN_BUCKET_ID + " as _ID"},
      "1=1) GROUP BY " + PhotoContract.ThumbEntry.COLUMN_BUCKET_NAME
           + ", " + PhotoContract.ThumbEntry.COLUMN_BUCKET_ID
          + ", ABS(0",
            null,
            PhotoContract.ThumbEntry.COLUMN_BUCKET_ID
     );

The selection field in the query call amounts to the WHERE clause of the resulting query. The "trick" is to add the GROUP BY clause here, after the WHERE clause at the end of the selection. The WHERE clause is enclosed in parentheses, so the trick is to add a closing parenthesis after the WHERE clause (which here is simply 1=1) by adding 1=1) to the selection. Then you can insert your GROUP BY clause. However, since Android will expect all of this to be the selection, it will add a closing parenthesis at the end! To overcome that you need to add something which requires a closing parenthesis at the end. I found it convenient to simply add ABS(0 to the grouping. This has no effect on the grouping, and it solves the syntactical problem, resulting in valid SQL:
SELECT images.bucket_display_name, images.bucket_id as _ID FROM images WHERE (1=1) GROUP BY images.bucket_display_name, images.bucket_id, ABS(0) ORDER BY images.bucket_id

Note I'm adding the required "_id" column using an alias without disturbing the grouping.
UPDATE for Android Q (API 29):
For this to work on API 29 (Android Q), column names must no longer be prefixed with table name. As in, images.bucket_display_name should be just bucket_display_name.
Comment: Was not able to make this hack work. It always adds an unwanted parenthesis. Maybe in previous versions it worked though...
Comment: Can you post the resulting SQL?
Answer: I found the answer myself:-
complete query is something like this-- Select * from table_name where column_name1 in (select distinct column_name1 from table_name) group by column_name1.
So, using the part after where from the above query in place of Selection in the question asked will give all the distinct column name.
Comment: This answer is not correct and it won't give distinct column names, instead you'll have error saying: SQLiteException: near GROUP

SQLite query using CursorLoader


Edit "new discussion" text in discussions list

Question: Hi in sharepoint 2013 community site home page you can see a webpart named "discussions list". In that webpart I wanted to edit "new discussion" text. Webpart properties also has no option to edit that text. Is there a way to edit this text or it cannot be edited??
Comment: No answer, but I need to be able to do this as well. In the previous version, was able to accomplish changing "add new discussion" to "add new assignment" using a content editor reference to a site asset document containing the necessary code. With the upgrade to 2013, this revision has been lost. Looking for a 2013 resolution. Thanks!
Answer: You can add JavaScript to the page to change the element's display text.
<code><script language="javascript" type="text/javascript">
jQuery(document).ready(function() {
   jQuery("a:contains('new discussion')").html("Your new Text");
 });
</script>
</code>
Comment: This is the best answer for me. The only thing I would add is to to change your jQuery statement to the following otherwise the little + sign dissapears:  $("a:contains('new discussion')").html("NEW WHATEVER HERE");
Answer: I assume you mean to edit an existing discussion. If I'm correct, Click on the Subject of the discussion item (hyperlink).. you'll see the item with "Like, Reply and  ..."
Click on "..." and you'll be presented with an option to "Edit".
Comment: No you have misunderstood the question. What I want is in the home page to start a new discussion there is a hyperlike named "new discussion". Is it possible to edit that text??


What is negative adsorption?

Question: In adsorption, the concentration of adsorbate is greater on the surface. So, how is it possible that the solvent will be more on the surface and the solute (adsorbate) in the bulk… or does solute not always mean adsorbate?
Answer: Solute does not mean adsorbate always.An Adsorbate is a substance that is adsorbed  on a surface of another substance. In a dilute solution, negative adsorption occurs as solvent is adsorbed by the adsorbent and not solute. In positive adsorption, solute is adsorbed.
Answer: Per a source:

If the concentration of the adsorbate is less than its concentration in the bulk then it is called negative adsorption. Example: When a dilute solution of KCl is shaken with blood charcoal, it shows negative adsorption.

The reference link also provides an educational video discussing also positive adsorption and related topics.

What is negative adsorption?


What would happen if I set up an amateur radio station in Canada without entering Canada?

Question: I have a US amateur radio license. I do not have a passport or Canadian amateur radio certificate. If I went near the border but stayed on the US side, set up an amateur radio station on a wheeled cart, enabled VOX (so I could talk on the radio without touching it), used a stick to push the cart into Canada, and began talking on the radio, am I subject to either US or Canadian amateur radio regulations?
Answer: A little poking around amateur radio sites will find (from the second link):

In 1952, Canada and the United States signed a Reciprocal Operating Agreement treaty. In the terms of the agreement, visiting Amateurs may operate in the host country in accordance with the rules and regulations of the host country.

You might want to check out https://ham.stackexchange.com/questions for further questions.
Comment: The station is in Canada, so "Under the terms of the agreement, the visitor must identify using his or her call sign followed by a call area suffix, e.g., VE3FRV/W9 or N9CFX/VE3". Where you are yelling from is irrelevant. The point of the agreement is to make the border pretty transparent to your operations.
Comment: Which country would I be subject to the laws of? I'm not in Canada, so I don't think Canadian laws apply to me, but the station is not in the US, so I don't think US law applies either.
Comment: Could I actually be prosecuted for a violation of Canadian regulations if i don't enter Canada? Of course if I ever went to Canada I could be prosecuted, but what if I never enter Canada after I do this? Could I be extradited for a violation of amateur radio regulations? (Note: I'm not actually considering doing this, I'm just curious what would happen if I did.)


Solve an equation using machine learning

Question: Imagine we have the following equation: y=xz. We have y but not other ones. Note that y  is like a matrix and we could as many sample we want. It is the values obtained from sensors. This means it will be a m*n dataset where m represents number of samples and n represents the number of sensors. I am wondering whether we can use machine learning techniques (any method including GAN) to solve the equation and get at least one of the variables of x or z. Thanks.
Comment: It's ridiculously easy to find a solution: pick the identity matrix for x and y for z.
Comment: Could you please give a toy example. We just have and don't have x and z.
Answer: Machine Learning is useful for problems which can't be solved (or not efficiently) with a deterministic method. The problem you propose is extremely simple since it doesn't even require any calculation, so there is no point using ML for it.

Could you please give a toy example. We just have y and don't have x and z

Suppose
$y=\begin{bmatrix}1 & 2\\
3 & 4\\
5 & 6\\
7 & 8\\
\end{bmatrix}$
An easy solution is to define $x$ and $z$ as follows:
$x=y=\begin{bmatrix}1 & 2\\
3 & 4\\
5 & 6\\
7 & 8\\
\end{bmatrix}$ and  $z=\begin{bmatrix}1 & 0\\
0 & 1\\
\end{bmatrix}$


lsp-mode tramp auto-completions

Question: Ive set up remote lsp-mode with tramp and pylsp server. While the server does start when I open a remote py file, many server features such as auto completions, code format, references dont work.
Here is my setup
<code>(eval-when-compile
  (require 'use-package))

(use-package lsp-mode
    :hook (python-mode . lsp)
    :config
  (lsp-register-client
   (make-lsp-client :new-connection (lsp-tramp-connection "pylsp")
                    :major-modes '(python-mode)
                    :remote? t
                    :server-id 'pyls-remote)))

;; Set tramp remote path
(add-to-list 'load-path "/usrlocal/share/emacs/site-lisp/")
(require 'tramp)
(add-to-list 'Info-directory-list "/usr/local/share/info/")
(add-to-list 'tramp-remote-path "~/envs/general/bin")
(add-to-list 'tramp-remote-path 'tramp-own-remote-path)

(use-package company
  :ensure t
  :diminish company-mode
  :hook (prog-mode . global-company-mode)
  :commands (company-mode company-indent-or-complete-common)
  :init)
</code>
Answer: Oh there's a typo
<code>(add-to-list 'load-path "/usrlocal/share/emacs/site-lisp/")
</code>
should be
(add-to-list 'load-path "/usr/local/share/emacs/site-lisp/")
Cant believe I spent 40+ hours debugging this
Comment: we've all been there

lsp-mode tramp auto-completions


Does the Jerk (derivative of acceleration) play a significant role in relativity?

Question: In particular, I'm thinking of spaghettification that occurs as an object falls into a black hole (as an extreme example). But what about tidal forces like the tidal heating taking place on Jovian Moons like Io and Titan?
Answer: Relativity is not really that essential for solving this problem, Newtons gravity is good enough. If you are asking how to calculate the tidal forces, all you have to do is calculate how the gravitational acceleration changes in given axis. For this, you can use derivation of accelaration with respect to position. Jerk has no effect, especially on circular orbit (otherwise you could use it to describe change of the tidal force in time). The formula for tidal force is following:
$F=-\frac{\text{d}F_g}{\text{d}r}R=\frac{2G M m}{r^3}R$
$R$ is the radius of the affected body.


How to build a programmer's portfolio that has no copyright issues?

Question: I would like to start writing my portfolio to improve my probability to get a job as a developer. I know that I can do small problems on my own but there are also libraries I use. What kind of guidelines there are to post code on the Internet? I mean, if I write code that uses Pandas and Matplotlib, do I have to ask a permission for the authors of the libraries to use their functions on a program that will be on the Github as I finish the program? Or is there copyright issues if I write the code such that it has not used other code from the Internet but downloads a code from Github, writes another source file and then compile or run the code the other script made?
Comment: I'm voting to close this question as off-topic because the people on https://softwareengineering.stackexchange.com/ are better equipped to answer it.
Answer:
What kind of guidelines there are to post code on the Internet?

Besides the fact that your portfolio should only contain code that you have written yourself (as it is meant to showcase your coding abilities), you must have the right to publish the code.
You have this right if

the code is not written as part of a contract or as part of your job, or
the contract specifies that you own the copyrights on the code, or
you have an explicit license from the copyright holder to publish the code

I mean, if I write code that uses Pandas and Matplotlib, do I have to ask a permission for the authors of the libraries to use their functions on a program that will be on the Github as I finish the program?

Technically, you need to have permission from the authors of 3rd-party libraries to write a program that builds upon such a library. This permission takes the form of a license.
In practice, there are two variations:

The library uses an open-source license. In this case, the library authors have granted the required license in advance to everybody that wants to use the library. These licenses promote sharing and definitely allow you to put your code up in a public repository. Both Pandas and Matplotlib appear to fall in this category.
You need to pay to use the library. In this case, you need to contact the vendor of the library to obtain a license and the license terms may or may not forbid you from making your code public.

One thing to be aware of: If you use a library (directly or indirectly) that uses the GPL or AGPL license, then the license terms require that your software is also made public under an open-source license.
Comment: The software that _you_ write (privately, not as an employee) is yours. It may not be functional without a third party library, but you can still publish it (without that library of course). As a potential employer, I can look at your code in that situation. I can actually run your code _if I have a license to the needed libraries_.
Answer: You first have to understand the difference between copyright, patents and software licensing.
You will have copyright on the work you produce by default.
If you use third party libraries then you have to check their license which will be something like MIT, BSD, GPL, L-GPL ... etc. Pandas is on a BSD 3 license and matplotlib has it's own license.
You also should note that in certain jurisdiction (USA is the main one here) you can create a patent on software which may mean that your work infringes on someone patent with which they can try to seek damages from you (Most likely start with a Cease and desist email).
Comment: "Work you produce" excludes work that you produce in the course of your employment. The copyright holder for such works is the company that pays your salary.
Comment: Depends on the contract and in the UK it's only for work produced on company time and on company equipment. Regardless not sure why you made that comment it makes no difference to OP as they aren't employed at the moment.


Ubuntu Touch: chromium port?

Question: There doesn't seem to be a chromium (or Google Chrome) port available in Ubuntu Touch (OTA10.1, bq M10). Does one exist, or are there any plans to have one (even without touch / small screen optimizations)?
Answer: The system browser in the phone/tablet images is based on the Chromium Content API, and so is roughly the same experience as one would have with Chromium.
If you wish to use Chromium as a legacy X11 app, you should be able to install it inside the legacy apps container with Libertine, in the same way that Firefox/Libreoffice are available.
Google does not provide generic ARM builds of Chrome, so the proprietary Chrome browser version will not be usable.
Comment: Thanks. I'm mostly interested in having access to Chrome/ium extensions, and being able to link sessions to my Google account. The built-in browser seems very basic, and doesn't seem to have any extension mechanism (or much configurability).
Comment: I'm looking into Libertine, but it doesn't look easy. The instructions at https://wiki.ubuntu.com/Touch/Libertine mention problems when Puritine is installed. Also, according to your answer in http://askubuntu.com/a/623311/532550 it looks like I would need to try to get it all working in a chroot.

Any additional hints before I completely mess up my tablet? ;-)
Comment: You don't need to do anything special to enable Libertine on the M10. The Ubuntu image there already comes with it installed. That is how Firefox/LibreOffice work there. Libertine/Puritine is the way to go. You should just be able to open the Libertine app, and either create a new container, or install chromium into an existing container. Then go to the Legacy Apps scope to launch Chromium.
Comment: To add to your reply, I just learned on #ubuntu-libertine (Freenode IRC) that things are not quite ready yet: "the Libertine GUI app itself is not installed on the M10 by default. proper integration of user-installable X apps is scheduled for OTA11 in a few weeks time"
Comment: It seems that your answer is the best I can hope for until OTA-11 comes out, so I'll accept that. Thanks again.
Answer: You can use the command line tools to install applications in a libertine container. First you create a container in the writable part of the file system. I used the instructions here
https://docs.google.com/document/d/1yJepibh68YaQijWO3Z3dWTtTTmzXnMmEE8eswhUXzw4/edit?pref=2&pli=1
The intsructions also tell you how to make a desktop file so it appears in the apps scope. I successfully installed emacs this way.
If you try to do this in the terminal app, you will run into problems due to lack of permissions. The easiest way around this is to start the ssh server with
sudo android-gadget-service enable ssh

Then run
ssh-keygen
cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
eval $(ssh-agent)
ssh localhost

Now you can follow the instructions and set up your libertine container and install applications. This script automates the process (I haven't tried it):
http://paste.ubuntu.com/16001183/
Comment: Mind you, I just tried this and it's not working with chromium for me. Other apps are fine so something about chromium is not playing nice with libertine.
Comment: I have tried it also, but chromium doesn't work so far.
Comment: Have same experience, Firefox is okay but chromium segfaults for some reason. Do not know how to debug yet. FF is like 4x slower (2000 vs 8000 octane) than built-in browser. I expect chromium to be about the native speed which should make it usable for running anything chromebooks can.
Answer: I am going to find a way to install Chromium on Ubuntu touch. The other methods mentioned here are not completely correct.
While it is true that Google does not provide arm64 builds for Chromium, valid working builds do exist. I have installed one that provides casting to my smart TV, on Manjaro linux. This was done on my Pinephone. Now however, I am running Ubuntu Touch on my Pinephone.
The state of Libertine containers is pretty messy today. It is a lot of hassle and does not work as advertised from the Settings --> System Screen. So to me Libertine is not the answer.
Comment: thats just a metapackage that installs the snap nowadays.
Comment: sudo apt-get install chromium-browser

Ubuntu Touch: chromium port?