How to modify and redirect the tankless water heater steam exhaust away from the house?

Question: I have a tankless boiler installed indoor for a house renovation job. There is a lot of constraints on where the exhaust pipe can be directed. Right now, it's directed 3 feet away from the house and pointed downward. Structurally, it's not possible to direct it to the roof. From time to time, the exhaust gas may travel (depends on the wind) to the entrance waiting area. It does not smell nice. How to best re-direct the exhaust to prevent such air travel?   Thank you so much for your suggestion and ideas in advance.
Comment: Photos would be useful.
Comment: Why is rooftop not an option?  It's the 'correct' solution.  After that - you are better off moving the water heater to a different part of the house.
Comment: Why does your tankless unit have a steam exhaust? What exactly is this unit? If it's the regular exhaust from a condensing unit (which can use PVC ducting), then you've got a few code requirements to deal with in keeping exhaust away from intakes and people. This particular situation does not look code legal. However, if this is *just* steam, you could always make a trap to condense it and let it simply overflow onto the concrete. Please add what type of unit this is.
Comment: Thank you for taking a look at the situation. I have attached a photo of the inside water boiler setup. The boiler is a Triangle Tube Prestige. How do I get a condensing unit (and what product to buy) to convert the steam into water? Would it impact the performance of the boiler in the long run? Thanks in advance!
Comment: Are you concerned about noise, or the water vapor (it's not steam)?
Answer: The fact that this is PVC (type IV ducting) tells me this should already be a condensing unit, so the amount of steam should already be minimal.
There's nothing stopping you from projecting that pipe further away from your house as long as it doesn't get withing 3 feet of your neighbor.
Based on your interior pictures, I'd recommend just drilling another hole in he side of your house closer to where your unit (which is generally the preferred way to vent the unit), which should move the steam far enough from your house vent based on the pictures you provided.
Else, if you think you are still likely to have issues with the exhaust, you really should move it up to the roof / chimney.
However, as long as you don't obstruct the airflow, you could minimize the steam of the current outside vent by running it into something like a dryer vent bucket:
https://www.homedepot.com/p/Everbilt-Indoor-Dryer-Vent-Kit-TDIDVKHD6/203626526
Be aware, that the exhaust from high efficiency water heaters is acidic and will eat away at any metals that might be part of your pail setup.
Comment: I was definitely NOT recommending venting inside as that will potentially expose you to carbon monoxide.  If you are really getting that much steam, I'd guess you have a unit that should be using Catigory III not PVC venting.
Comment: Thanks! I have attached how it's installed on the inside to give more perspective on this. I would like to find out what solution on the outside I can do. It's also not ideal to vent indoor because of the heavy steam. Heads for the heads up on the acidic outlet. You are right. This unit has such an outlet at the bottom and it was eating away the copper and the copper needs to be replaced now.


PyGTK treeview - same column - with checkbox or text

Question: I wanted to ask, if someone knows how to create a treeview, which consists of two columns.
The first column is a description column, and the second column consists depending on the leaf, of a text or checkbox. I have to program it with pygtk version 2.0 (!).
Like
Column 1,          Column2
Test_1
    RPM            2700
    Model          NameXXX
    Active         [X]
Test_2
    RPM            1000
    Model          NameXXX
    Active         [ ]

How should I program column2?
test_data = [
        { 'column0' : 'test00', 'column1' : 'test01', 'f': '#000000', 'b': '#FF00FF' },..]
column0 = gtk.TreeViewColumn("Column 0", gtk.CellRendererText(), text=1, foreground=2, background=3)
        treeview.append_column(column0)

the code before allows the user to set the foreground and background depending the row. i would like to do the same with the cell renderer, i hope you can help me :/
Thanks!
Comment: I don't think you can do this. Instead, make RPM, Model, and Active their own columns. For Active, use a GtkCellRendererToggle.
Answer: To do this, you would have to create a renderer whom can render other renderers (renderception!)
So you create a dynamic renderer which holds a text renderer and a toggle renderer and some sort of type property to decide which one you want to use when rendering.
Connect all relevant signals to the custom renderer you just created and pass them through to the selected renderer.
For the values, create a property which can hold both values (boolean & text, I have no idea how to do this in python) and pass them through to the correct property for the selected renderer.
There is a example in C. I don't know if you'll understand it but hey, it's a start!
https://github.com/matze/EggPropertyTreeView/blob/master/egg-property-cell-renderer.c


How to electrically hook up my humidifier to my furnace and have it run when furnace is running and not A/C in summer

Question: How do I hook up my humidifier to my furnace so it only runs when furnace heats my house.  Just want to make sure it does not turn on when A/C in summer goes on.  The person who installed my furnace did not hook it up and is not answering my calls.  Thanks
Answer: On most newer furnaces, on the control board there are specific terminals for a humidifier.  The engineers have built into this control board the exact criteria that you are looking for.


How do I made this screw tube not have an invisible wall?

Question: So I basically want this ball to run down the ramp, into the tube and out.
But for some reason, the screw tube creates this invisible wall that prevents the ball from going in. The screw tube has Rigid body (passive), and it's shape is Mesh - Deform.
Comment: What is the shape of the ball set to? If it's set to something other than sphere, then try sphere. If that is what it's already set to, then try convex hull or mesh. This may or may not make a difference, but it's probably worth trying. And if it doesn't, you may want to share your .blend, by uploading it to [Blend-Exchange](http://blend-exchange.giantcowfilms.com/) and editing your question to include the link given to you once the upload is complete.
Comment: Thanks, the ball was set to Sphere, tried convex/mesh, still didn't do much, but I uploaded the file to be downloaded.
Answer: The reason your simulation isn't working as expected is because the tube has a screw modifier on it that hasn't been applied.
Apply the modifier to make the geometry real, and it will work just fine. You also should apply tranforms with Ctrl+A rotation and scale (in object mode) on  all objects involved in the simulation. Otherwise the simulation can become unstable and have unexpected results.
Comment: Thank you so much! It works! Thought the screw modifier was applied already. All works well now :) So when I keep adding new obstacles, do I just select the all again, and apply transforms (rot/scal) again, or just select the individual and apply?


Point-biserial correlation with unequal groups in dichotomous variable

Question: The dichotomous variable I want to use for a point-biserial correlation has very unequal n's ($n_1=140$, $n_2=6$). Would this be breaking any rules? What would this mean for my results? Would it just limit the statistical power?
Comment: 1) No, it doesn't break formal assumptions for point-biserial _r_. 2) Yes it does limit statistical power.
Answer: I would first look at a scatterplot of the variables to see if they are linear before running an analysis. In addition, see Kraemer's 1980 paper,Robustness of the Distribution Theory of the Product Moment Correlation Coefficient, in which it is noted,

Robustness of normal test theory for correlation coefficients is at
  least asymptotically ensured for bivariate distributions satisfying a
  linearity and a homoscedasticity condition for the null theory and a
  further kurtosis condition for the nonnull theory. If any one of these
  conditions fail, it may be demonstrated that robustness may fail as
  well. (Abstract)
Comment: One variable is continuous. The dichotomous variable has the unequal group sizes.


How to turn sin(arcsinh(x)) into algebraic form?

Question: How can I turn $\sin({\sinh^{-1}{x}})$ into explicit algebraic form ? I've tried to plug in $\sinh^{-1}{x}$ into sine's exponential form $\frac{e^{ix} - e^{-ix}}{2i}$, but then I cannot think of any ways to simplify that.
Comment: Sorry, I mistypes -- I have corrected it
Answer: Using this,
We need $\sin\left[\ln(x+\sqrt{x^2+1})\right]$
Now $e^{i\left[\ln(x+\sqrt{x^2+1})\right]}=\left[e^{\left(\ln(x+\sqrt{x^2+1})\right)}\right]^i$
and $e^{\ln(z)}=z$
Answer: This is not possible.
Impossibility proofs are always very hard; therefore hear the following arguments:
If there were a "simple algebraic relation" $\Phi(x,y)=0$ between the variables $x:=\sinh t$ and  $y:=\sin t$,  valid for all $t\in{\mathbb R}$, then this "algebraic relation"  would have to mimic somehow that for all $y\in[{-1},1]$ there are an infinity of values $x_k$, all of them satisfying $\Phi(x_k,y)=0$. An "algebraic" expression $\Phi(x,y)$ would not be ale to accomplish this.
Another hint in this direction is the following: If such a $\Phi$ existed in your example then a similar $\Psi(u,p)$ would exist for the much simpler example relating the variables $u:=\cos t+i\sin t=e^{it}$ and $p:=e^t$ valid for all real $t$. Such a relation would empower you to calculate trigonometric functions using a table of logarithms.


Does anyone know the font of the Zitana logo?

Question:
What the font has no answer at all. We created the logo more than 5 years ago.
Comment: Hi Sven, welcome to the site. We have some [font identification question requirements](http://meta.graphicdesign.stackexchange.com/a/2366/8708), I've made some edits to your question so that it meets them. Next time, please be sure to check that first!
Answer: This is Arkitech Light by Neogrey Creative.

I found this using What Font is, a font search engine similar to WhatTheFont but it searches free fonts. Any time WhatTheFont can't identify a sample, it's a good indication that it's a free font.


What is the process that causes a collapsing star to bounce back?

Question: Can someone explain the process by where a star collapses and bounces back.  I haven't been able to find a good explanation of the bounce.
Edit here, I was wondering specifically where the energy of the bounce comes from.  It seems like the mass must decrease in proportion, or the energy must have beens stored some other way. I guess the mechanism is not completely understood, or I would ask that question.
Comment: possible duplicate of [Why does a supernova explode](http://physics.stackexchange.com/q/63558/)
Comment: @RobJeffries: OP asked for the reason for the *collapse and* bounce, which makes it a duplicate (your edit to remove the collapse bit seems a bit too much, IMO). DilithiumMatrix's answer does actually cover the bounce, though the detail of the eos should be included & is not.
Comment: @KyleKanos This question is not a duplicate. The reason for the "bounce" is reasonably well understood and is only peripherally connected with why a supernova explosion occurs. I will edit the question to make that clear; but the reason for the bounce (the hardening of the EOS subsequent to a dynamical freefall) is not contained in any of the answers to the duplicate either.
Comment: @KyleKanos The casual reader would think that you are claiming that the cause of the bounce and the reason that a supernova explodes are the same thing. Indeed, your now-deleted first comment, made when you marked the question as a duplicate, essentially said just that. The former is well understood, the latter is not. I rolled back the edit, since I agree it would be preferable if the OP decided whether to accept that this was a duplicate.
Comment: @RobJeffries: I'm claiming that the collapse and bounce is the beginning of a supernova event; this is what OP asked about and why it's a duplicate.
Comment: @KyleKanos But does not explain "Why does a supernova explode". And neither could my answer to this question be posted as an answer to the (non-)duplicate.
Comment: The last paragraph of my answer directly addresses your edit. The energy is stored as the potential energy of the compressed neutrons.
Answer: The bounce, as opposed to the supernova which is still somewhat mysterious, is caused by a drastic hardening of the equation of state (EOS - the relationship between pressure and density).
Prior and during core collapse, the EOS is dominated by relativistically degenerate electrons - a relatively soft EOS. The beginning of core collapse (initiated either by photodisintegration of iron nuclei or the removal of electrons by electron capture) leads to increasing densities, and causes free electrons to combine with protons to form neutrons (neutronisation) whilst resultant neutrinos escape. This drastically softens the EOS further, leading to a free-fall collapse of the core on a dynamical timescale of about 1 second.
As the number density of neutrons increases, non-relativistic neutron degeneracy pressure becomes important. NRD neutrons are less compressible but, contrary to pop-sci myth, this pressure cannot halt the collapse alone - it was established by Oppenheimer & Volkoff (1939) that the upper limit to the mass that could be supported by ideal neutron degeneracy pressure was $<0.75M_\odot$ and all collapsing stellar cores are more massive than that. Instead it is the extreme hardening of the EOS due to the repulsive strong nuclear force between neutrons once they are closely packed (within about $10^{-15}$ m) that stops the collapse. Because the collapse occurs dynamically, rather than quasi-statically, the inner core overshoots any kind of equilibrium position (in much the same way as when you compress a rubber ball). Once the collapse halts, the core is then able to rapidly expand outwards, using the stored potential energy in the closely-packed neutrons, towards an equilibrium configuration and this is what is termed "the bounce".


How to measure up/download speed from my apache web server?

Question: I wish to see who has accessed my server and what speed they have downloaded the website at.  How can this be done?
Answer: 'Who' can be seen in  your access logs, the location of which is configurable but defaults (in debian) to /var/log/apache2/access.log
'What speed' can be garnered by using the Custom Log module and dividing %B (bytes sent) by %T (time to serve the request).
Comment: +1 on the speed calculation - I hadn't thought of that.
Answer: If by "who", you mean "what IP addresses", then yes, that information should be in your apache access_log. Also in that log, you'll find information as far as how much data was tranferred.


How to rename video `title`?

Question: When exporting a video from iMovie it asks for a title. Upon saving the file you'll find it has named the file whatever you input for the title. Now if you rename that file in Finder then open it in QuickTime and show the Movie Inspector, you'll find that the video title is the old title - the title you input in iMovie. Unfortunately you can't edit the title here. It doesn't show the title in Finder's Get Info. So my question is how can you edit the video's title (not filename) without reexporting the movie from iMovie?
Answer: If you are running Mac OS X and find that some of your video files have metadata included, then it will have been set in Apple's iTunes. In iTunes you can add, edit or remove all metadata from video files. This is only applicable to certain video types, however, as they must be iTunes recognized filetypes. The file types supported by iTunes are the same as those supported by QuickTime, and so if you have QuickTime plugins installed, you will be able to utilize those as well.
Open iTunes on your Mac.
Click "Movies" or "TV Episodes" on the left.
Select the video you want to edit, right-click it and click "Get Info."
Click "Video." Highlight each field of data and press "Delete." Click "Info" and edit.
Or use free tool MetaZ ( http://griff.github.io/metaz/ )

How to rename video `title`?


What would be the best way to format a time range?

Question: I have a chart control and a time bound value.
The control displays the value aggregated over equal intervals of time.
It is important to display the corresponding time range for each aggregated data point.
This time range has to be accurate, readable, yet as compact as possible because the available space is limited.
The size of intervals can be 15 min, 30 min, 1 hr, 3 hr, 6 hr, 12 hr, 1 d.
The readings can start at any moment of time, so the edges of intervals are not aligned or rounded to the time grid.
The smallest time unit is 1 minute.
Comment: Can you provide a screenshot to illustrate this? At present, it's difficult to understand the problem that you're trying to solve.
Comment: just added, take a look
Answer: Is there a reason to have a single point which shows the range? I would imagine that this could work better with discrete 'range start' and 'range end' points, like this:

You probably wouldn't need to display the year in this context, as the year will be defined by plot as a whole. You will need to think about time zones, though... you may want to define the time zone being presented somewhere on the page.
One could even image these range start/end indicators functioning as handles, allowing you to dynamically select the range.
Comment: I really like your idea. Unfortunately the time for reworking the control the way you suggested won't be approved. Out of the box it only displays a single point, not a range. But can be something the vendor who developed the control might want to consider in a future update.
Answer: If you want it to be compact, only mention values that change over the interval.
Don't mention the year unless the interval includes midnight after New Year's Eve.
Don't mention the month unless the interval includes midnight after the last day of a month.
Don't mention the day unless the interval includes midnight.
Users should be able to gather the other units from other parts of the view, so...

For instance, I can tell from view elements other than your white-on-black text block that the graph is for July and August.
I actually can't see that it's for 2013, but you can fix that easily by including that in the top bar with the months.
I can see that the day is the 22nd in this case, but if you are not already doing so, you would want to make sure that there is always a date sitting at the top of your black line (start point marker), as there is now.

All of this means that the majority of cases will involve mentioning just the time (no date) for the start point, and then you have two choices for filling in the rest of the information, of course.
You could give the start point and just the interval duration, as mentioned by Liviu A, for minimum size.  Since what I am suggesting would cut down on the amount of text for the start point, though, you could also specify the end point, and the resultant increase in readability should be worth the slight increase in space.  Again, in most cases this will just be a time.
examples: ("2013", "July", and "22" gathered from other elements of the view)

6:15PM, 15min
6:15PM–6:30PM

a few other choices, if you are serious about compactness:

** 6:15–6:30PM (since "PM" is something else that does not change over the interval)
6:15–30PM (hour also does not change) (this one might sacrifice readability too much)
18:15–18:30 (24-hour time saves space (no AM or PM) and for some users is easier)
18:15–30 (most compact, but probably too far)

** sample:

These should be easy changes from your current design.
(Actually, specifying the end point gives an advantage:  Since your largest interval is 1 day, a user will know any interval ends on the day after the start point when the end point is an earlier time.  This means that if you choose to show the end point, you will really only need times for all cases, and not just most cases.)
Answer: I think it's a solution to divide graph area on two zones:

Visual analysis zone – for quick grasping points or patterns and selection. There is very quick orientation in this zone as it is visual, not reading zone for rough analytics and picking interesting points.
Quantitative analysis zone – for precise analytics. Here is left-to-right in-row eye scanning and reading pattern used. As you can see, there are a lot of space for exact time interval and other values.

The advantages are:

taking into account specifity of information perception by human (images – quick, reading – slow)
clean graph area (zone 1)
placing all values for precize analytics in one area (zone 2) for creating analysis flow
a plenty of space for an accurate and readable time formatting
Comment: What would be disadvantages of this?
Comment: One disadvantage I see is a bit harder task for searching exact time interval in zone 1, as it is displayed at zone 2, not so close to cursor position. But making interval more noticable (there is enough place for this) solves this problem.
Answer: One solution would be to display it something like this:
6:24 pm + 3h, Jul 22, 2013
6:12 pm + 15m, Jul 22, 2013
etc
basically just show the start time + the interval's length; i think this way it would be easier for the users to figure out what the interval represents
---- added some more info
depends on what information is important to your users:

in this case they will need to if they want to know the exact time the interval ended (not sure if this really important for your users)
in the case where you display start-end time, they will have to solve a little math problem if they want to know what the interval length is

it seems to me that in practice the second case will be harder to do, because as you've mentioned the timestamps aren't starting at fixed intervals
so something like 17:47-18:02 is not as apparent as 17:47 + 15m. Also, this way you get an instant sense of what scale the graph is showing (ie. data at 15minutes intervals, etc).
Comment: So you are suggesting to solve a little math problem instead of displaying the answer right off?
Comment: added some more info
Comment: I disagree; I suspect to most people, it would be clearer if you show the start and end times than if you show the interval. Like bonomo says, you're asking people to do maths to work out what the range is instead of just showing the range like they originally asked.
Comment: @LiviuA, when you say it like that it makes perfect sense https://www.youtube.com/watch?v=0TYdrfm7yaI


All questions and answers should have citation

Question: Should we make it a part of FAQ that all of the questions and answers should have citation needed either from Quran or Hadith? Please give your reviews. Thanks
Answer: The problem with this suggestion is that not all answers are necessarily solvable by citing a reference from Qur'an or hadith.
For example, in my question regarding Mormonism, it would be difficult to find a direct reference since Mormons plain did not exist during the time of the prophet.  There may be plenty of scholarly debate on the topic, but if I'm limiting my answers only to those which directly cite the Qur'an or hadith, I may never get a chance to see them.
I would agree that the general practice should be to cite an official source when it both is possible to do so and makes sense for the question, but pushing it as a general rule doesn't help.
Comment: +1 - not everything requires a reference from the primary sources. For example if I asked you what Imam an-Nawawi's position was on something, I'd be looking for a reference from his works. The important thing is to add references back to the sources.
Comment: I came here after reading [this answer](https://islam.stackexchange.com/a/21419) which seems like a comment than a proper answer. So this site currently doesn't have a 'cite sources' rule? The question you asked on Mormonism does have a couple of answer with references so probably is not a good example of what you are suggesting here.
Comment: @sv. Comments should never be used to answer questions, and an answer without sources or references is still an answer. Whether it's a *good* answer or a *bad* answer is up to the community to decide, that's what votes are for.
Comment: I understand how voting generally works on SE sites. I think you are implying that this site currently doesn't have or follow the 'cite sources' rule. Maybe the community here could revisit this policy and establish a minimum quality standard so answers here can actually be verified against some source. Otherwise casual readers like me cannot trust what's written on this site. Just a thought.
Comment: @sv. If you feel that's a policy worth adopting, go ahead and collect your arguments into a new meta post to propose it; that's exactly what meta is for.
Answer: To keep it short and sweet we will make a rule something like this
Where ever it is possible to cite a source do so and encourage others to follow
Answer: I think it makes sense for answers, but I am not so sure about the questions. I don't think it should be a requirement for questions, but it can be encouraged.
Answer: We should absolutely request references as much as possible. Islam is a religion of knowledge and one built upon knowledge. Therefore, I propose highly encouraging citing references as much as possible.
I consider the following as valid references, since everybody is at a different level:

Verses of Qur'an
*Ahadith of rasulullah
Statements of companions
Statements of scholars
Fatawa (eg. Islam-QA)
Notes from classes, lectures, etc.

The latter group of these allows us to still cite proofs even though the methodology of deriving the proof may be beyond our current understanding. That doesn't negate the proof.
I would recommend encouraging people to look things up and source things if they have proofs that are not strong (eg. statement of a parent, friend, or random person).
Comment: What about my case. I know some of the answers, as I have been told by scholars, but do no remember their exact words, nor do I have any citation. As long as the answer is right, would it be okay?
Comment: @Dynamic google it. I'm sure you can find a similar source online somewhere. If not, well, your answer may not win
Answer: I don't think imposing such rules is necessary or helpful.
If an answer is good it is good, if it is bad it is bad, simply having citations to Quran or hadith is not a good indicator of the quality of an answer.
The acceptable sources will also be a source of disagreement, for example why not accept references to Muslim scholars and only accept citations to Quran and hadith? Which hadith are acceptable? etc. One can also make fake or irrelevant citations to get around the rule.
If you think an answer needs to cite sources to become a good answer that is fine, but I disagree with imposing it on other users as a policy. If you think an answers needs to be justified by giving references to sources then you can politely ask its author to provide references (or clearly state that it is personal opinion).
You are probably trying to make sure that the answers are not subjective personal opinions. The SE system already has methods and policies to deal with these issues, I am against making up additional restrictions on the kind of answers users can post until you demonstrate a need for them.
On the other hand, I am fine and would support encouraging users to try to support their answers by citing references (which should include not only Quran abd hadith but also other Islamic literature like works of Muslim scholars and experts).


Java - Clip and Looping Sound

Question: I finally got my sound clip to work in my java application.
This is picky, but there's a minor pause between each sound loop. Is there any way to "merge" the two loops slightly so the sound seems continuous?
Answer: The short answer is, you can do it with two copies of the cue being played back alternately. Probably not what you wanted to hear, because you have to write the code to manage this yourself rather than, say, rely on a parameter that could be passed to the built-in looping functionality.
The implementation I came up with and am currently using has as its core algorithm, this:
while loop periodically calls a runnable that plays the cue (or its twin, determined by a boolean switch) on its own thread, and has a sleep increment set just a bit below the length of the duration of the WAV file.
It helps to have the cue itself start and end in silence, but ramp quickly at the overlap point, as one might do a splice with Sound Editing software. If the cue doesn't start/end in silence, there is a chance of having clicks when the sound starts or stops.
Answer: See Clip.setLoopPoints(startFrame,endFrame).

Java - Clip and Looping Sound


how do i align line segments that are supposed to branch off from another line?

Question: this is something i surely should know by now but i've somehow found a way to avoid it being a problem up to this point. is there an easy way to connect these lines so that they look as if they are branching off from the horizontal line? i've tried everything in the 'Align' toolbar but nothing is really giving me what i want. thank YOUUU
Comment: Its *not* possible to "connect" paths to the middle of other paths.
Answer: Enable Smart Guides so that you can see when the anchor intersects the V-shaped path.
Hold down Shift to constrain the path vertically
Answer: If you want them to remain strokes then you can try this- first off, turn off smart guides (View> Smart Guides and uncheck), select the top anchor point on one of the vertical lines and nudge it either up or down as needed with the up/ down arrow keys on your keyboard. This may require you go to Illustrator> Preferences> General and reduce the "Keyboard Increment" to a pretty small number- this will depend on your drawing/ stroke size. You can position the Stroke End Caps to be hidden under the horizontal line. Strokes cannot actually be joined in a middle section. They can only be joined to an open end point.
If you do not require those vertical lines to remain as strokes then you can go Object> Expand to turn them into separate filled paths . Then go to Window> Pathfinder> Unite to actually join them into one shape.


Difference between instantons and sphalerons

Question: What is the difference between instantons and sphalerons? If they are different, how do they violate baryon and lepton number in the standard electroweak theory?
Answer: The sphaleron is kind of the opposite of the instanton, and kind of the same. Let's make that statement precise:
An instanton is a local minimum of the action that mediates vacuum tunneling (link to an answer of mine how and why instantons do that). The sphaleron sits in-between the vacua, in a certain sense, it is the instanton "in the middle of tunneling":
Given an instanton configuration $A_\text{inst}$ on a 4-cylinder $(-\infty,\infty) \times S^3$, representing tunneling between two vacua at the spatial slices at $t = \pm \infty$ with Chern-Simons winding numbers differing by 1, the sphaleron is vaguely the field configuration $A(t = 0)$, and precisely the field configuration for which, at some time $t_0$, the winding number as the integral of the Chern-Simons form
$$ \int_{{t_0} \times S^3}\omega \equiv \int_{{t_0} \times S^3} \mathrm{tr}(F\wedge A - \frac{1}{3}A \wedge A \wedge A) $$
is exactly the mean of the winding numbers of the vacua at the ends.
The idea is that an instanton of winding number 1 mediates between vacua of winding numbers $k$ and $k+1$, and that the sphaleron is the field configuration "in the middle", with winding number $\frac{2k+1}{2}$. The reason this is interesting is because, for example, in the electroweak theory, the bosonic potential part of the action is (of course) minimal for the vacuum/instanton configurations, and maximal for the sphaleron configuration. That's why the sphaleron is called that (it's Greek for slippery thing) - it may slip down into either vacuum configuration because it is sitting in a metastable extremum of the potential.
Comment: Interesting, I've never heard of a sphaleron. So, following your conceptual explanation, would a Coleman de Lucia instanton (e.g. tunneling from de Sitter to Minkowski) be a sphaleron at some stage?
Comment: @SRS in sphaleron processes the energy barrier is crossed from above the barrier (as opposed to tunneling) through thermal fluctuations.
Comment: @JamalS: I have no idea, because the CdL instanton is in a slightly different setting (string theory/theories of gravity).
Comment: @ ACuriousMind - The physical mechanism by which instantons violate fermion number is tunneling. But what is the mechanism by which sphalerons violate the fermion number?
Comment: @SRS: I've never understood this kind of phrasing. Quantumly, you find that the symmetry that usually would conserve baryon/lepton number is anomalous, and that its non-conservation is exactly the Chern class/winding number. I honestly do not understand how one can meaningfully talk about the *process* that creates that anomaly, since it is simply the result of the transformation of the path integral measure under the symmetry transformation.


unexpected Goods recieved - area of Concern?

Question: I have received a parcel today of a fake pair of Ray Ban sunglasses.Posted from a Chinese company. A receipt was included . The receipt listed my correct phone number, incorrect details of my credit card and the cost was listed as $198 US.I have checked all of my bank statements and cannot find any cost that correlates. Is this some type of new scam? The receipt is listed for a company as BayBan.
Comment: Does this answer your question? [Received a package but didn't order it](https://money.stackexchange.com/questions/114928/received-a-package-but-didnt-order-it)
Comment: Also https://money.stackexchange.com/questions/131097/unexpected-goods-delivery-is-this-a-scam-and-what-kind-of-scam
Comment: I had almost the same question 2 1/2 years ago. https://money.stackexchange.com/questions/131097/unexpected-goods-delivery-is-this-a-scam-and-what-kind-of-scam  Most likely to get a good review. Nothing else happened. Also listed a credit card number that supposedly paid which I didn't know.
Answer: One common scheme is that they need positive reviews, usually on Amazon marketplace.
So they take a bunch of random addresses, place an order through the marketplace for one of their products to be shipped to that address, wait for it to show up as delivered, and then enter a 5 star review.
Since there was an actual payment and an actual delivery, it will show up as a "verified" review, and contribute to better ratings and better position in search results, which should help them sell a lot more products and cover the negligible cost of some fake stuff and extremely cheap postage.
Using addresses or randomly chosen people will help defeating anti-fraud systems which would scream if they only shipped items to themselves (in China…).
If that is what is happening, there is no specific financial risk for you. It just means your name+address+phone number are listed somewhere (like the phone directory…).
There is possibly an extremely marginal risk that customs could have found about the package containing a fake and come bother you saying you imported fake stuff, but I'm not even sure they do that in the US at all (and in countries where they actually do it, they are extremely unlikely to do that for a one-off low value item).
If they used someone else's card rather than a legitimate card, then there would be a risk that the police could come knocking on your door saying you bought the item using stolen card details. I have no idea how they go around checks on the issuing country of credit cards, but I would be surprised if they used stolen cards, as a high number of chargebacks would probably be an even bigger red flag, so I would think they instead use other (legitimate) means of payment.
The final risk is that if you use the product you received it may completely fail any safety rules, so just don't.
If you really want to be on the safe side, go to the police and tell them you receive this while you didn't order it. You probably can't file a complaint about this (you didn't suffer any damages), but they should be able to record this and/or provide a document stating you advised them. This of course by itself isn't enough to exonerate you, but it will be positive indication in case this ever goes somewhere. Tell them to keep the item as evidence or destroy it (them, not you).
Note that I am considering only the "fake reviews" case here. If indeed someone used your address to ship stuff bought with stolen card details, expecting to be able to retrieve it before you, the risk would be higher, but it seems unlikely for a pair of cheap fake sunglasses. The advice would be the same though.
Answer: It's not a new scam, it is an old one.
Here's how it works. They steal someone's credit card and order things online to be shipped to someone else's address, in this case yours. Then a porch pirate may come by since they know all the tracking information and steal the package. You may have gotten to the package before they did.
If they bought items with a stolen credit card and had it shipped to their own address the police could easily find them.
Comment: But a *single* pair of fake Ray Bans?
Comment: This isn't the only possibility; it could be fake reviews or similar. See the answers I linked in the comments. In any case: if you didn't order it, you are under no obligation to return it or pay for it; you can use it, or throw it out, or whatever seems appropriate.
Comment: the corollary being that the OP may be contacted by the police regarding a order passed to their address using a stolen credit card
Comment: @RonJohn - A $200 pair of Ray Bans
Comment: @JohnFx *fake* RayBams, according to OP.
Comment: Genuine BayRans, they go well with my Rolodex watch.


Should I submit XML sitmaps directly or list them in my robots.txt?

Question: Are there advantages to listing XML sitemap files in robots.txt vs submitting them directly to Google via Webmaster Tools?
Answer: It seems these days that a sitemap in the root named sitemap.xml will get picked up by dang near anyone in time.
It all depends on how much control you want.
If you do not want just anyone reading your sitemap including scrapper bots, then name it something unique and submit it to Google, Bing, and who ever else you want. Do not put it in your robots.txt file.
If you are not worried about who reads your sitemap, it is mostly enough to just create a sitemap file in the root named sitemap.xml. Bing, Yandex, and Baidu all found mine just fine without anything in the robots.txt file. However, if you want it more widely known and more easily picked up, then use the robots.txt file. I would still submit it to Google and Bing manually. That way you can see some info about how many pages have been indexed from the sitemap etc. I do not think that Google specifically looks for a sitemap if one was not submitted. Things may have changed recently where they do.
Also consider that some of these domain stat sites look for sitemaps and will report it. So if you make it publicly known, it will really be publicly known to anyone including script kiddies. There are scrapper bots reading the sitemaps and spidering sites.
While I do not have anything in my robots.txt, my sitemap file is in the root and named sitemap.xml. It is being reported on domain stat sites. I generally do not have any regrets over this, but once the genie is let out of the bottle, it is hard to stuff back in. Just keep that in mind.
Comment: "see some info" - Yes, I found that you had to manually submit the sitemap for GWT to report anything about it. Simply having an entry in robots.txt was not enough, although _I think_ (?) Googlebot did still request the sitemap (a regularly named "sitemap.xml" file) before this.
Comment: Years ago, I did use a custom named sitemap for Google. The only reason why mine is not this time is because of a brain-fart. ;-) I created the new code here on the dev box and forgot to rename the file output before deploying the new code. Ooopppsss! This is the price of getting old. I do not recommend it. I decided just to leave the code and submit the new standard named sitemap. It is more in the past year or so that others started blindly looking for a sitemap. I have no real heart-burn over this, but it may have been better to stay private to stop the bat rastards.


Does Windows 7 support multiple mouse drivers being installed?

Question: I use a laptop for work that plugs into a docking station to which my Logitec G5 mouse is connected.  I often take my laptop home where I will connect my Logitech G500.  To my understanding, these two mice use the same drivers, so there shouldn't be any conflicts.  However, I am thinking of buying a non-Logitech mouse for work.  I'd like to know that the non-Logitech drivers will work for the non-Logitech mouse while my Logitech drivers will work for my G500 when I take my laptop home.
Comment: You can install as many mouse drivers as you like. Windows will always use the driver for the device that is actually connected.
Answer: You can install an unlimited amount of drivers (mouse or otherwise). In reality though, nearly all mice use the same standard mouse driver provided by Microsoft.
Comment: But if it's a specialized mouse with 4 additional buttons in excess of the standard 3, wouldn't I need the drivier specifically for that mouse?  Do mouse drivers use the mouse-specific driver as well as Windows's underlying drivers?  How does that work?
Comment: For every device, Windows uses the best matching driver. Your special mouse can probably function with Microsoft's default driver, but those extra buttons might not function. When you install the special driver, Windows will use that instead.


Do I need to purchase additional licenses for external developers logging in periodically?

Question: If I were to hire an external developer to customize my Salesforce org, how do they get access? Am I required to purchase an extra license just for them to do the initial setup, and make modifications every now and then?
Comment: Ask your account executive about a Limited Login License, which allows only a few logins per month. They're less costly than normal licenses, with the obvious limitation that they can't log in more than a few times a month.
Comment: You can purchase one extra license and assign it to your active developer.
Answer: If you are talking about Community/Portal users, then yes.
If you are talking about internal/platform users, then that's going to be tough. Actually, you're talking about a user who has to make configuration changes to your org, so that is, by definition, an internal user. You won't be able to buy a limited login internal license unless you have some serious spend with Salesforce.
I wish I had better news. You'll just have to deactivate another user while this contractor/consultant is working.


Synchronize calendar between Mac, Android mobile and Windows 7

Question: I´m currently using my Mac with Lion. Using Bootcamp I installed Windows 7. I also have an Android phone. Now I´m looking for a calendar software that allows me to synchronize between all three OS. It should not be an online solution.
Comment: By online solution, will your android sync via USB or do you simply mean that you want to self-host the data as you don't trust a free or paid CalDAV/ Exchange service?
Comment: Sorry I should have make this more clear. I just don´t want to put my data into an online solution so that I don´t have any control about it.
Comment: By running your own server you control all changes to the software stack, all outages, all data privacy and backup. For some, these are needless hassle, for many the costs of this control are of such value that they wouldn't dream of having their personal or professional data in a shared sevice - even world class ones run by Apple, Microsoft or Google.
Answer: Your best option is probably Google Calendar. It is an "online solution", but you don't have to make use of the webapp at all, just use it as a method to sync.
For OSX, you can use iCal synced to Google Calendar using CalDAV. It's not perfectly polished, but it works fine. You may need to enable any other calendars via the Delegation tab, under Accounts in the iCal preferences.
I'm not an Android guy, but I think Google Calendar support should be automatically set up when you activate your device with a Google account.
For Windows 7, it depends what app you're wanting to use. It looks like they removed the Calendar app from Vista. The simplest option may be this desktop gadget that syncs to Google Calendar. If you're looking to use other software, Google provides a sync option for Outlook, or you can use anything that supports the CalDAV standard.
Answer: Selecting bootcamp severely narrows your options.
The prevailing solution for nearly all calendar clients is to use CalDAV/Exchange for sync. Unless you are OK with storing your calendar data on a file server (like TimeCapsule) or FAT external storage that will let a cross-platform client that use one common data store sharing the same file format, you will need to have one if your OS to mount the others native file system to read/write the calendar data.
Once you get that working, you can decide how best to sync your mobile device.
My guess is nothing self-contained will be workable and you will either host your own CalDAV store locally or co-located (hello lion server!) or you will have to relax your exclusion of online solutions.
Comment: Start with [Mac Mini Colocation](http://macminicolo.net/) as a baseline for what you'd want to host your data and then shop for a local or DIY hosting as your needs dictate.
Comment: The hosting isn´t a problem. I have some servers running at home.
Comment: If you already have any sever, CalDAV is clearly the winning move unless you feel inclined to pay for exchange licenses.


What is the electric field and potential inside and outside grounded conducting and non grounded conducting sphere?

Question: I'm taking an electromagnetic theory course, but I have trouble understanding the field and potential inside and outside of a conductive sphere when it is connected and not connected to ground.
And why is the voltage inside the ball connected to the ground zero?
Comment: Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer.
Comment: What is the electric field and potential inside and outside grounded conducting and non-grounded conducting sphere
Answer: The conducting sphere is a Faraday cage: The field inside it is zero. What does the grounding do for that? Nothing!
Remember that the electric field is the gradient of the potential and does not change when you add a constant to the potential. What the grounding does is fix that constant.


Translate "Strong by Choice"?

Question: I would like to translate "Strong by Choice" to Latin as a motto for a charity. We have tried per arbitrium fortis but want to know if this can be improved.
Answer: Fortis is a good word for "strong".
A harder problem is to find a good word for "choice" (or the verb "choose" if you are willing to reword a little).
Arbitrium means a legal judgement, a decision by an arbiter, an opinion, a decision, and similar things.
A better option would be optio, which means free choice and the liberty to choose.
(There is also the verb optare.)
Another option is voluntas, which is more in the direction of desire, free will, and choice.
The most appropriate tone depends on what suits your purpose.
I recommend that you compare these words in any online Latin dictionary.
The correct form of fortis depends on what it refers to.
If it refers to a single person, it is fortis (singular masculine or feminine).
If it refers to a group of people, use fortes (plural masculine or feminine).
If instead of people it refers to an institution, use forte (singular neuter).
The most idiomatic way to say "strong by something" is to put the something in ablative.
Using per is grammatical, but I find that a plain ablative gives more gravity.
Therefore my suggestion is:

Voluntate/optione fortis/fortes/forte

This leaves you with six choices, depending on the exact circumstances and nuance.
The ablatives of the nouns voluntas and optio stay the same, no matter which form of fortis you choose.
Comment: Hi Joonas, thank you very much for your assistance. As we are a collective (an online mental health forum/community) I think that the 'fortes' would be the most appropriate form. Would that mean I would have to change the conjugation of the verb? Or is 'Voluntate fortes' grammatically correct?
Comment: @GeorgeGinger I'm glad to be able to help! In that case I agree that *fortes* is the best choice. The form *voluntate* is independent of the form of *fortes*, so *voluntate fortes* is grammatical. I just added a remark to my answer to underline this. // If you think that your question has been sufficiently answered, please mark one of the answers as accepted by clicking the little check mark on the top left corner of the answer. After getting 15 reputation points you will be able to vote up any questions and answers you like.
Answer: "Eligimus fortis esse"; (We Choose to be Strong) fortis also means brave; powerful; resourceful: all of these fortify the effect. Possibly, a bit militaristic, for a charity; but, then, so is "Onward Christian Soldiers".
Comment: *fortes* ***?***
Comment: @Hugh: Thought about that. The concept " (to be) strong" is one concept, singular. To say "We Choose to be Strong People; then, yes, fortes.
Comment: @tony: It doesn't work like that in Italian (as well as the other Romance languages). Why would it work like that in Latin?
Comment: Vincenzo Oliva: In an anguish of indecision selected the wrong option. The human capacity for making a mistake; then, justifying it. One of the boons of this site is that errors are rapidly picked up, by colleagues, which is as it should be.
Answer: You could try a fun supine construction: "Fortis Actu Sumus" literally meaning "We are strong with respect to doing."

Translate "Strong by Choice"?


Autofocus is not working for my Nikon AF-S 70-200mm f/2.8 SWM VR IF ED G

Question: I bought used lens (Nikon AF-S 70-200mm f/2.8 SWM VR IF ED G) from eBay. Not sure why Auto focus is not working. I tried outdoor photoshoot with
1/100 f3.2 102mm ISO 100. This is VR1 lens.
I tried with and without tripod and I have Nikon D600 body. Lens contacts looks good to me. Please let me if I miss anything.
AF and VR switch is ON. Distance is around 5 meters.
Comment: You mean it fails to take the shot in great focus, or there is no evidence that it even tries to focus?
Answer: It sounds like the lens may be faulty or broken.
That lens should autofocus with that camera. Even with the focus limiter switch set to '∞-3m' it should be able to focus on a subject 5 meters away.
Assuming your outdoor shoot is during daylight hours and your focus target has sufficient contrast there is no reason why the lens should not be autofocusing correctly.
Here are a few things to try before concluding the lens is faulty:

Try another lens on the same camera in the same shooting conditions with the same subject. Does the other lens autofocus properly?
Just to be on the safe side, set the focus limiter switch to 'Full' (Your 5 meter estimate may actually be just below 3 meters).
Aim at a very high contrast target. Does the lens AF then?
Comment: It worked after setting focus limiter switch to full. Thanks!
Comment: Thanks for the quick response Michael. I did photoshoot during daylight. I have 14-24mm and 50mm lens for both the lenses autofocus is working properly. I will try to set the limiter to switch to 'Full' and let you know the result.


Running Django with FastCGI or with mod_python

Question: which would you recommend?
which is faster, reliable?
apache mod_python or nginx/lighttpd FastCGI?
Answer: I've done both, and Apache/mod_python tended to be easier to work with and more stable. But these days I've jumped over to Apache/mod_wsgi, which is everything I've ever wanted and more:

Easy management of daemon processes.
As a result, much better process isolation (running multiple sites in the same Apache config with mod_python almost always ends in trouble -- environment variables and C extensions leak across sites when you do that).
Easy code reloads (set it up right and you can just touch the <code>.wsgi</code> file to reload instead of restarting Apache).
More predictable resource usage. With mod_python, a given Apache child process' memory use can jump around a lot. With mod_wsgi it's pretty stable: once everything's loaded, you know that's how much memory it'll use.
Comment: Is your preference for Apache/mod_wsgi still the case, nearly 2.5 years later?
Comment: If anyone still cares, separating out your wsgi server with uwsgi or gunicorn, and fronted by the web server of your choice, is the direction that's worked best for every project I've seen. Staying with Apache is somewhat of a death sentence for your website.
Answer: lighttpd with FastCGI will be nominally faster, but really the time it takes to run your python code and any database hits it does is going to absolutely dwarf any performance benefit you get between web servers.
mod_python and apache will give you a bit more flexibility feature-wise if you want to write code outside of django that does stuff like digest auth, or any fancy HTTP header getting/setting.  Perhaps you want to use other builtin features of apache such as mod_rewrite.
If memory is a concern, staying away form apache/mod_python will help a lot.  Apache tends to use a lot of RAM, and the mod_python code that glues into all of the apache functionality occupies a lot of memory-space as well. Not to mention the multiprocess nature of apache tends to eat up more RAM, as each process grows to the size of it's most intensive request.
Answer: Nginx with mod_wsgi
Answer: Personally I've had it working with FastCGI for some time now (6 months or so) and the response times 'seem' quicker when loading a page that way vs mod___python. The critical reason for me though is that I couldn't see an obvious way to do multiple sites from the same apache / mod_python install whereas FastCGI was a relative no-brainer.
I've not conducted any particularly thorough experiments though :-)
[Edit] Speaking from experience though, setting up FastCGI can be a bit of a pain the first time around. I keep meaning to write a guide..!
Answer: I'm using it with nginx.  not sure if it's really faster, but certainly less RAM/CPU load.  Also it's easier to run several Django processes and have nginx map each URL prefix to a different socket.  still not taking full advantage of nginx's memcached module, but first tests show huge speed advantage.
Answer: There's also mod_wsgi, it seems to be faster than mod_python and the daemon mode operates similar to FastCGI
Answer: I'd recommend WSGI configurations; I keep meaning to ditch apache, but there is always some legacy app on the server that seems to require it. Additionally, the WSGI app ecology is very diverse, and it allows neat tricks such as daisy-chaining WSGI "middleware" between the server and the app.
However, there are currently known issues with some apps and apache mod_wsgi, particularly some ctypes apps, so be wary if you are trying to run, say, geodjango which uses ctypes extensively. I'm currently working around those issues by going back to  fastcgi myself.


Do I need to install GFCI outlets at each location for switched garage lights?

Question: I am wiring up multiple switched outlets in garage ceiling for the garage lights and i am assuming they all need to be GFCI protected. So my question is must I install GFCI outlets after the switch for each outlet. It would mean two of the outlets would be GFCI and I am installing 2 LED lights to plug into each outlet that only are drawing .4 amps each. It seems kind of ridiculous to install GFCI for switched outlets dedicated to these lights.
Comment: Putting a GFCI on the ceiling is illegal, regardless; they have to be accessible to be able to reset them.
Comment: Can you identify the first outlet or junction box in the circuit feeding these garage lights and outlets?
Comment: All garage receptacles must be GFCI protected there are no exceptions so a breaker or if the lighting is fed from a receptacle that can be reached , the other option would be to hard wire the lights, then GFCI is not required.
Answer: Any GFCI device is capable of protecting any number of loads downline.  At extremes, Europeans use one GFCI device for their whole house but this requires compromises that make it a bad idea here.  Therefore, it is unusual to need more than one GFCI per circuit.  Most of the time, when people fit multiple GFCIs on a circuit, there's a sad knowledge gap there, which is causing them to waste money.
GFCIs are not receptacles.  Those things are GFCI+receptacle combo devices.  They also make GFCI+circuit breaker combo devices, as well as standalone GFCI (they look like a receptacle, but with no pins, and the slang is "Deadfront").  There is no way to plug in anything to a breaker or deadfront, so their whole point is to protect downline loads.   But GFCI+receptacles can do it too.
Regardless, as long as these receptacles are on the ceiling such that they're for obviously lights only and not readily accessible for other loads, ask your local inspector if you can exempt them from GFCI requirements.  If you can't, using GFCI receptacles on the ceiling is prohibited. You need to be able to reach them to reset them! This forces you into a downline design.   And another factor does too...
Putting a GFCI device downstream of a switch is bad design, and will play havoc with many models.  In that case the GFCI needs to be upstream of the switch and feed both hot and neutral of the switch+light section of the circuit, so the GFCI proper is never switched. By nature it must be one GFCI.
Comment: The handbook has a commentary after 210.8.a.2 (GFCI. Garages) there are no exceptions all 120v 15 & 20 amp receptacles installed in garages must provide GFCI protection, but I agree with your thinking. A hard wired light would not need GFCI.
Answer:
Ceiling might be exempt

The pros will have to weigh in on this, but I seem to recall that there is an exemption for receptacles truly out of reach.

Just need ONE GFCI

Assuming everything is on one circuit, put in a GFCI either at the panel (a breaker with GFCI built in) or put in a GCI receptacle prior to the first of the switches/switched receptacles. Then wire everything else off of the LOAD side and it is all protected.

Never put GFCI in the ceiling

Whether or not GFCI is required for ceiling receptacles (which may be up to your local inspector to decide), if you do install GFCI never actually install it in the ceiling. Install it in the panel or in an easily accessible (low on the wall) receptacle. You don't want to have an occasional problem tripping the GFCI and have to climb a ladder to press the little RESET button. Oh yeah, in the dark because the GFCI turned out your lights.

Hardwire the lights and avoid the question

If you hardwire the fixtures then you don't need GFCI. There are plenty of LED fixtures available designed to be permanently wired. In my limited experience, I have found them to be of better overall quality than similarly priced plug-in fixtures.

Assumptions:

No need to use two separate circuits - lights are low power. In fact, you can put in another receptacle, which may make sense.

You don't want to switch to hardwired lights but want to stick, for whatever reason, with plug-in ceiling fixtures. But I still suggest reconsidering hardwired fixtures to avoid the GFCI problem.

According to Ed Beal, GFCI required for ALL receptacles in the garage.

Recommendation

Run a single 20A regular circuit (12/2, regular breaker). No need for GFCI (you'll put in a receptacle) and no need for AFCI (as I understand it, garages are one of the few areas still exempt)

First device on this circuit: 20A GFCI + dual receptacle. Incoming 12/2 goes to LINE. You now have a properly protected convenience receptacle at normal height, which also protects the lighting receptacles.

Connect LOAD with 12/2 to both switches. If they are in the same box, pigtail black->switch hot/switch hot, neutral white passes through (just connect white to whites of both outgoing cables). Outgoing cables are black switched hot (2nd screw on the switch) & white neutral (from the LOAD side) to the receptacles for the lights. If they are in different boxes (not clear from the original question), then you have black hot (from receptacle)/hot (to switch)/outgoing hot (to 2nd switch) connected together and the cable to the 2nd switch has its white tied to the other neutral/white wires.

Cables up to receptacles in ceiling are now each black switched hot/white neutral. Install ordinary receptacles (dual 15A or dual 20A or single 20A - any will do fine) in the ceiling for your lights.

If your GFCI trips for any reason, the RESET will be conveniently at the light switch instead of up in the ceiling or back at the panel. You've saved money by using only one GFCI device. You've also saved by only using one circuit.
If you decide to go with hardwired lights (now or later) then you use the junction boxes in the ceiling for wiring instead of receptacles and you can then move the LOAD stuff to pigtail off the LINE side instead - which takes your lights OFF of the GFCI protection while still keeping the convenience receptacle properly protected and available for use.
Comment: @John1shot, using two breakers with 12/3 is a problem.  Check out [this question](https://diy.stackexchange.com/q/160851/43874) (written by the other guy that answered you, Harper) for more information.  Basically, you can do it, but you need a double pole GFCI breaker.
Comment: Thank you for all the input, My plan was to run 12/3 and use the red wire for one outlet circuit & the Black wire for the other outlet circuit on two separate switches for different light banks in the ceiling. It might be more expensive but i most likely will just buy two GFCI breakers for the box that way the circuits are protected prior to the switches
Comment: @JPhi1618 100% correct. And in any case, with a few LED lights (low power as stated in the original question), there is no reason to use 2 circuits. I'll update my answer to clarify.
Comment: Also, even using a double pole breaker, you run into the issue of loosing all your lights if the GFCI trips as manassehkatz mentioned.  One reason lights are on separate circuits are to avoid loosing lights when something bad happens to the outlets.
Answer: I absolutely agree: keep your lighting circuits and your receptacle circuits separate; that way, if anything ever happens to the receptacles, you aren't in complete darkness.  I see you have been explained all the options: you can either use receptacles or hard wire (i prefer hard wire in a junction box). If you installed one GFI inline first in the circuit, if there's ever an issue, now all your lights are tripped off by one GFI. Why not just make it its own  15A lighting circuit on 14/2 wire, which saves some $, and be done with it?
As to my advice? I recently wired a garage for an individual 25 x 20 and ran all his lighting circuits separate. Now his garage receptacles per 2020 code had to have a dedicated 20 amp circuit with GFCI protection, so I decided to use the breaker type GFCI.  knowing that, we simply used GFCI 20 amp breakers for all receptacle circuits.  Now he has already spent enough money with these GFCI Breakers there was no reason for me to run my lighting circuits on a trip device other than the breaker itself.
You have some options; the beauty of the electric trade is that there are those options along side what has to be.  Hope it works out.  If there's no way to steer away from plug-in style lights, then I agree with the gentleman: just put one GFCI outlet in line first and protect the rest of them.  You'll have to deal with the fact that it may trip and you have to reset it, but that probably won't happen unless one of the lights goes seriously wrong.


Which is the best Class for Download and upload data from iPhone?

Question: I am developing application in iPhone, Where i need to download and upload data from webservice. Please advice me which is the best class or Framework to achieve this and also please let me know which is the best xmlparser.
Answer: you can use asihttprequest and asihttpresponse for establishing connection use restful api and nxxml parser for parsing the data comes from server
thanks
Answer: NSXMLParser is a SAX parser included by default with the iPhone SDK.
TouchXML is an NSXML style DOM XML parser for the iPhone.
Answer: If your web service has the ability to return json, I would highly recommend doing so and using http://code.google.com/p/json-framework/. Especially if you have a complex XML document.
As for connecting to the service, it's pretty straightforward - all you need is a method to handle the connections. While there are 'frameworks' out there, it's as simple as creating a method such as "getDataFromService:(nsstring *)param1" and within that method issuing a request.
I think the bigger question you'll need to answer is how to authenticate with the service, if required.  If the service uses OAuth, http://code.google.com/p/gtm-oauth/ is a great framework.


Stop Word 2007 from automatically converting sequence of English letters to Korean

Question: I am using Word 2007 on a computer with Windows 7 Enterprise SP1 Korean version, but the Windows interface has been changed to English (User interface is completely in English, including all menu items, and installed programs detect system language as English). Text services and Input languages have been installed, and I can use it to switch between Korean and English using the 한/영 key
I am having a problem in Word (and I am supposing it happens in other Office programs like Excel or Powerpoint, but I haven't tested it) where typing seemingly random English letter combinations gets converted to their Korean equivalent. For example, typing a word (a variable name, for example) that contains a sequence cpe followed by a symbol (., space, etc) automatically converts cpe into 첻 (this is what you would have got if the keyboard was in Korean mode and you typed in the keys c, p and e in sequence). I have autocorrect set to it's default settings, normal correction of typos while typing in English works as expected.
How do I prevent Word from automatically changing English character sequences to Korean? I am not really sure what exactly triggers this conversion as I feel it is happening randomly (though I am pretty certain typing certain letter sequences followed by a space or . usually causes this to happen).  Is there a way to disable this "inter language autocorrect" feature? I still need to be able to switch between English and Korean input when I want to do it manually.
Answer: Try to clear the Detect language automatically check box. Maybe that will help you
Comment: Where would that checkbox typically be found?


Minimax: how can I implement it in Python?

Question: As long as I've been a programmer I still have a very elementary level education in algorithms (because I'm self-taught). Perhaps there is a good beginner book on them that you could suggest in your answer.
Answer: As a general note, Introduction to Algorithms. That book will get you through pretty much everything you need to know about general algorithms.
Edit:
As AndrewF mentioned, it doesn't actually contain minimax specifically, but it's still a very good resource for learning to understand and implement algorithms.
Comment: CLRS does not contain minimax.
Answer: Look at the wikipedia article on Negamax: http://en.wikipedia.org/wiki/Negamax. It's a slight simplification of minimax that's easier to implement. There's pseudocode on that page.
Answer: There is an implementation of minimax as part of an othello game here (and for browsers here).
Stepping through this with a debugger and/or through use of logging statements
may supplement theoretical descriptions of the algorithm.
This visualization applet may also help.
At each stage the player will choose the move which is best for himself. What's best for one player will be worst for the other player. So at one stage the game state with the minimum score will be chosen, and at the next stage the game state available with the maximum score will be chosen, etc.


Using Hertzian contact mechanics to explain fracture cones when an elastic sphere is pressed onto an elastic half space

Question: I'm trying to understand the Hertzian cone fracture process from a continuum mechanics point of view. I'm considering a problem where an elastic sphere is pressed quasi-statically onto an elastic semi-infinite space. Following chapter 2 in the reference Handbook of contact mechanics Ch. 2 by V. L. Popov, M. Hess, and E. Willert. The Cauchy stress tensor in the elastic half space takes the following form (cylindrical coordinates):
$$\sigma_{ij} =
\begin{bmatrix}
\sigma_{rr} & 0 & \tau_{rz}\\
0 & \sigma_{\theta \theta} & 0\\
\tau_{rz} & 0 & \sigma_{zz}
\end{bmatrix}$$
The $z$ axis points down into the half space, the $r$ axis points parallel to the initially half space surface, and $\theta$ is the azimuthal angle (rotations around the z-axis). The shear stresses $\tau_{r\theta}$ and $\tau_{z \theta}$ are zero by symmetry. The components of the stress tensor takes the following explicit form:
\begin{equation}
\begin{split}
\frac{2\sigma_{rr}}{3p_0} &= \frac{1-2\nu}{3} \left(\frac{a}{r}\right)^2 \left[1- \left(\frac{z}{\sqrt{u}}\right)^3 \right] + \left(\frac{z}{\sqrt{u}}\right)^3 \frac{a^2 u}{u^2 + a^2 z^2}\\
&+\left(\frac{z}{\sqrt{u}}\right)\left[\frac{1-\nu}{a^2+u}u + \left(1+\nu\right) \frac{\sqrt{u}}{a}\arctan\left(\frac{a}{\sqrt{u}}\right) - 2 \right],
\end{split}
\end{equation}
\begin{equation}
\begin{split}
-\frac{2\sigma_{\theta \theta}}{3p_0} &= \frac{1-2\nu}{3} \left(\frac{a}{r}\right)^2 \left[1- \left(\frac{z}{\sqrt{u}}\right)^3 \right]\\
&+\left(\frac{z}{\sqrt{u}}\right)\left[2\nu +\frac{1-\nu}{a^2+u}u - \left(1+\nu\right) \frac{\sqrt{u}}{a}\arctan\left(\frac{a}{\sqrt{u}}\right) \right],
\end{split}
\end{equation}
\begin{equation}
\begin{split}
-\frac{2\sigma_{zz}}{3p_0} &= \left(\frac{z}{\sqrt{u}}\right)^3 \frac{a^2 u}{u^2 + a^2 z^2},
\end{split}
\end{equation}
and
\begin{equation}
\begin{split}
-\frac{2\tau_{rz}}{3p_0} &= \frac{rz^2}{u^2 + a^2 z^2}\cdot \frac{a^2 \sqrt{u}}{u+a^2}.
\end{split}
\end{equation}
I hope I got all of those factors right. $\nu$ denotes the Poisson ratio of the elastic half space. $a$ is the contact radius between the sphere and elastic half space. $p_0$ is a mean stress. For our purposes $\nu$, $a$, and $p_0$ can be considered constants. $a$ and $p_0$ set the scale for lengths and stresses.
The parameter $u$ is defined as
\begin{equation}
u = \frac{1}{2} \left(r^2 + z^2 - a^2 +\sqrt{\left(r^2 + z^2 - a^2\right)^2 + 4a^2 z^2}  \right)
\end{equation}
The eigenvalues of the Cauchy tensor (the principal stresses) are
\begin{equation}
\begin{split}
&\sigma_1 = \frac{1}{2} \left( \sigma_{rr} + \sigma_{zz} + \sqrt{\left(\sigma_{rr}-\sigma_{zz}\right)^2 + 4 \tau_{rz}^2} \right),\\
&\sigma_2 = \sigma_{\theta \theta},\\
&\sigma_3 = \frac{1}{2} \left( \sigma_{rr} + \sigma_{zz} - \sqrt{\left(\sigma_{rr}-\sigma_{zz}\right)^2 + 4 \tau_{rz}^2} \right).
\end{split}
\end{equation}
Now in the references, B. R. Lawn,  A. Franco, and P. D. Warren, et. al. these equations are used to argue for that cone fracture can be understood. For instance in B. R. Lawn Fig. 2 looks like this:

I have then read that this diagram is supposed to explain cone fractures because outside of the contact area AA $\sigma_1$ (most positive principal stress) changes from being compressive to tensile.
In H. Chen et. al. there is a relationship between the direction of the cone crack. In the z-r plane this relationship is
$$\frac{dz}{dr} = \frac{\tau_{rz}}{\sigma_1-\sigma_{rr}}.$$
My issue is that I do not understand how the figure explains cone cracks, and how the above relationship comes about. The above relationship looks alot like the angle necessary to rotate the coordinate system to obtain principal stresses. Finally, I have a vague idea of that the cone cracks are supposed to follow the trajectories of one of the principle stresses but I do not understand why.
If anyone can elaborate on these issues I would be very thankful.
Answer: I think that this equation represents the differential equation for a streamline of a vector field, where the numerator and denominator correspond to components of the eigenvector related to one of the principal stresses.
If you solve the eigenvalue problem, you get the eigenvalues that you present in your question. Continuing this process, you get the following eigenvectors
\begin{align}
&\mathbf{v}_1 = (\sigma_1 - \sigma_{zz}, 0, \tau_{rz})\, ,\\
&\mathbf{v}_2 = (0, 1, 0)\, ,\\
&\mathbf{v}_3 = (\sigma_3 - \sigma_{zz}, 0, \tau_{rz})\, .\\
\end{align}
According to this, the streamlines associated with $\sigma_3$ are the solution of the differential equation
$$\frac{dz}{dr} = \frac{\tau_{rz}}{\sigma_r - \sigma_{zz}}\, .$$
When I compute a streamline starting in the surface at the end of the contact radius, I get the following

Given that I am obtaining the same streamline that the authors, I would guess that it might be a typo.


Is there a way to import a MS SQL .db.back (database backup) into PostgreSQL?

Question: I've received MS SQL backups from a client, I'm wanting to import/restore them into a PostgreSQL environment.  Is this possible?
Answer: I have no first-hand experience. You could try these to start - but if all you've got is a dump, that's just the data. If you don't also have the creation of the DB itself scripted out (the DB schema), you're kind of hosed.
/edit -
Answer: One way of getting this to work is to download a copy of SQL Server Express, and restore the backup there. Sometimes this doesn't work, so you could try downloading a trial version of SQL Server Standard. I think it has something like a 180 day trial.
Once you got the database restored, then you can use your favorite ETL tools to move the data into PostgreSQL.


Django-admin clean_fields override, keeps previous data on submit

Question: My question is quiet simple, I have a class in my app model that inherits from models.Model.
I'm overriding the clean_fields method of the django-admin, in order to execute some custom validation to my form.
The problem is that when it raises a ValidationError from my custom validation, if the user tries to submit the form again with the correct information, it always keeps the data from the previous submit.
class SignedOffModelValidation(models.Model):
    class Meta:
        abstract = True

    def clean_fields(self, exclude = None):
        super(SignedOffModelValidation, self).clean_fields(exclude)

        errors = {}
        if getattr(self, self._meta.immutable_sign_off_field, False):
            relation_fields = [
                f for f in self._meta.fields
                if isinstance(f,(models.ForeignKey,models.ManyToManyField,))
                and not f.name.endswith('_ptr')
            ]

            for field in relation_fields:
                try:
                    field_value = getattr(self, field.name)
                    signed_off = getattr(
                        field_value,
                        field_value._meta.immutable_sign_off_field
                    )
                except (AttributeError, ObjectDoesNotExist,):
                    continue
                else:
                    if not signed_off:
                        msg = u'In order to signeoff, %s needs to be Signed Off' % \
                            (str(field_value),)
                        errors[field.name] = ([msg])
            if errors:
                raise ValidationError(errors)

Any help would be appreciated!
Best Regards
Comment: I have a hunch that your problem is associated with the view/form that is manipulating this model. Any chance you can post that?
Answer: You should use the clean() method rather than clean_fields(). This is pretty clear in the Django documentation.


Dell poweredge 1650 server blinking orange

Question: I have an old server running for my application. I just checked that it has started flashing orange suddenly from blue. Does anyone know what does this mean?
Comment: I assume you are talking about one of HDD lights?
Comment: What O/S do you have running on the system?
Comment: Craig- OS is Linux
Answer: Install the Dell Openmanage Server administrator and see what it tells you. Last time I installed this, I don't believe it required a restart, which is good if you possibly have failing drives.
Since I assumed you were running Windows, HERE is the link for the Linux documentation for OpenManage
Answer: According to the Dell PowerEdge 1650 Systems Installation and Troubleshooting Guide it means there's a problem. It's most likely a harddrive related problem, so I suggest you check the HDD lights (link goes to HDD part of the guide).
Comment: If it is hard drive problem, can I check from terminal if there is any issue with hard drive ?
Comment: I suggest you check the other answer. While I'm not familiar with Openmanage, I'm willing to bet that it has the utilities needed to diagnose the issue or find the problematic harddrive.
Answer: If it's a Windows machine yes just install Dell OpenManage, open the webportal and browse to System->Storage->Virtual Disks and it will show you the status of all virtual disks.  If it turns out its not the hard drive browse to Systems -> Logs and it will describe why the alert is on.
You can do the same on a unix machine, or there are live versions of open manage you can install on a CD and boot to and read the Dell hardware logs via that.


HP Trim data migration to SharePoint online

Question: how can HP trim Data can be migrated to SharePoint online,
Is their any tool ?
How it can be possible
Answer: We used TRIMBocX solution to integrate HP TRIM and SharePoint O365 and keeping it insync. You can use the same for migrating HP TRIM to SharePoint Online O365. TRIMBocX suite is capable of connecting to legacy HP TRIM and new HP RM with SharePoint On premises and Online.
Answer: There are vendors out there that supply tools and consultancy to do this (I work for one so I'll avoid posting links). It's not cheap so make sure you are getting exactly what you want.
If you are still within your support period speak to HP as they do have some export tools that work quite well and then you only have to worry about getting content into SharePoint.
If you are outside of you support period and you have a competent dev team you can do this yourself. Avoid the APIs and go straight to the DB as the TRIM schema is not overly complex. You can then extract the relevant metadata and the binaries to a file share and move them into SP from there.


MAUI and platform binding libraries

Question: I'm trying to setup a MAUI app primarily for Windows and Android devices. I have a BT printer that the supplier provides libraries (in form of JAR and DLL files) for.
I'm trying to add to the MAUI app the JAR library using the Android Java Library Binding as a separate project. The project builds itself but, when I add to the MAUI app, I receive errors regarding the lack of support by the library for other platforms (iOS, Windows).
Reading some other threads the solution should be to add a MAUI class library (where for every platform I can add specific code) but I don't know how can wrap the JAR library into it for Android.
In Xamarin Forms it's more simple: refer the Android Binding Library (Xamarin) by the app.android project and all is done.
So can I do the same for MAUI? Can I have one printer library for every platform I want to support and, via iOC, refer the right library for the right platform?
Thanks in advance Andrea.
Answer: just for someone that has the same question, I have resolved editing by hand the csproj file and adding conditional project referencing like this:
<code><ItemGroup Condition=" '$(TargetFramework)' == 'net6.0-android31.0' ">
    <ProjectReference Include="..\Your.CodeFor.Android\Your.CodeFor.Android.csproj" />
</ItemGroup>
<ItemGroup Condition=" '$(TargetFramework)' == 'net6.0-windows10.0.19041.0' ">
  <ProjectReference Include="..\Your.CodeFor.Windows\Your.CodeFor.Windows.csproj" />
</ItemGroup>
</code>
Now I can specify different project reference for different platforms, only an IntelliSense warning appears when use the reference that lacks code for platforms that is not intended for.
Andrea.

MAUI and platform binding libraries


Whited00r firmwares for 3GS and iPod touch 4G?

Question: Currently Whited00r has not released any firmwares for iPhone 3GS and iPod touch 4G , are they planning to release it in the near future?
Comment: How can we know? Did you check their site?
Comment: Welcome to Ask Different. If you don't get good answers, you can edit this to remove the speculation part about what someone/some group intends and simply explain in a little detail what you ultimately want to do and where your research has left you without an answer.
Comment: The same reason we don't have [Bootlace](http://lifehacker.com/5693309/how-to-install-android-on-an-iphone-in-six-easy-steps) past the iPhone 3GS.
Answer: Currently, the whited00r project only supports the iPhone 2G, 3G, iPod 1, and iPod 2. The following is from the whited00r website.

Whited00r is the biggest community of iOS modding and firmware cooking in the world. Here you will find full support for all Apple devices equipped with the ARMv6 CPU:
  iPhone 2G & 3G, iPod Touch 1G, 2G.

So as to why they didn't release it, there are several reasons.

The iPhone 3GS and the iPod 4 clearly don't run the ARMv6 CPU. They run the A4 chip (according to the specs, the iPhone 3GS has a ARMv8-Cortex, which is supposedly part of the A4 chip. Correct me if I'm wrong). The A4 chip is also on the iPhone 4, which shows that the devices are very capable, unlike the supported devices which can barely play new games.
The goal of the whited00r project is to bring new iOS features to old devices that cannot go past iOS 3/4. The iPhone 3GS and the iPod 4 can go up to iOS 6.1.6, which packs plenty of new features.
Whited00r is basically a new user interface. If you want your devices to look like iOS 7, jailbreak your device (http://posixspwndownload.com for iOS 6.1.3-6.1.5 and http://evasi0n.com for iOS 6.0 to 6.1.2) and grab Winterboard and a iOS 7 theme.

Sorry if this was a little harsh, but the whited00r team has reasons for not supporting them. If you want more info, I suggest contacting the team at firstname.lastname@example.com.


Python garbage collection

Question: I have created some python code which creates an object in a loop, and in every iteration overwrites this object with a new one of the same type. This is done 10.000 times, and Python takes up 7mb of memory every second until my 3gb RAM is used. Does anyone know of a way to remove the objects from memory?
Comment: Related: http://stackoverflow.com/questions/759906/sys-getrefcount-continuation/759970#759970
Answer: I think this is circular reference (though the question isn't explicit about this information.)
One way to solve this problem is to manually invoke garbage collection. When you manually run garbage collector, it will sweep circular referenced objects too.
import gc

for i in xrange(10000):
    j = myObj()
    processObj(j)
    #assuming count reference is not zero but still
    #object won't remain usable after the iteration

    if !(i%100):
        gc.collect()

Here don't run garbage collector too often because it has its own overhead, e.g. if you run garbage collector in every loop, interpretation will become extremely slow.
Answer: You haven't provided enough information - this depends on the specifics of the object you are creating and what else you're doing with it in the loop. If the object does not create circular references, it should be deallocated on the next iteration. For example, the code
for x in range(100000):
  obj = " " * 10000000

will not result in ever-increasing memory allocation.
Comment: Python will automatically collect objects with circular references, *unless* any of the objects in a reference cycle have __del__ methods.  If that's the case, garbage objects are moved to the gc.garbage list, and you will have to manually break the reference cycles.  It's better to try to avoid having both __del__ methods and reference cycles.
Comment: One solution to avoiding reference cycles is to use weakrefs: http://docs.python.org/library/weakref.html
Comment: I am creating circular references in my object. Can't it be deleted manually?
Answer: This is an old error that was corrected for some types in python 2.5. What was happening was that python was not so good at collecting things like empty lists/dictionaries/tupes/floats/ints. In python 2.5 this was fixed...mostly. However floats and ints are singletons for comparisons so once one of those is created it stays around as long as the interpreter is alive. I've been bitten by this worst when dealing with large amount of floats since they have a nasty habit of being unique. This was characterized for python 2.4  and updated about it being folded into python 2.5
The best way I've found around it is to upgrade to python 2.5 or newer to take care of the lists/dictionaries/tuples issue. For numbers the only solution is to not let large amounts of numbers get into python. I've done it with my own wrapper to a c++ object, but I have the impression that numpy.array will give similar results.
As a post script I have no idea what has happened to this in python 3, but I'm suspicious that numbers are still part of a singleton. So the memory leak is actually a feature of the language.
Comment: This shouldn't exactly be responsible for the problem as described, though; even Python 2.4 should reuse freed memory (it just didn't return it to the operating system).
Comment: Not sure if my experiment is correct but temporarily creating millions of floats definitely had constant memory usage. Putting the same floats in a `list` increased the memory usage 100MB/s. That was on 2.7... so I guess at least in 2.7 the problem doesn't exit? Am I missing something?
Answer: If you're creating circular references, your objects won't be deallocated immediately, but have to wait for a GC cycle to run.
You could use the weakref module to address this problem, or explicitly del your objects after use.
Answer: I found that in my case (with Python 2.5.1), with circular references involving classes that have __del__() methods, not only was garbage collection not happening in a timely manner, the __del__() methods of my objects were never getting called, even when the script exited. So I used weakref to break the circular references and all was well.
Kudos to Miles who provided all the information in his comments for me to put this together.
Comment: If any object in a cycle has a `__del__` method, then the cycle isn't garbage collected by `gc`. See https://stackoverflow.com/a/15974956/1959808
Answer: Here's one thing you can do at the REPL to force a dereferencing of a variable:
>>> x = 5
>>> x
5
>>> del x
>>> x
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'x' is not defined

Comment: In a typical program, it's easier and clearer to just let your variables go out of scope than explicitly deleting them. Of course, if your whole program is one single long function then nothing will go out of scope until it ends. Which is one reason that a single long function is not a recommended way of writing programs.
Answer: weakref can be used for circular object structured code as in the explained example

Python garbage collection


Login to wordpress using another sites authentication.

Question: I am looking for a solution to access wordpress through another websites login authentication. Most of the pages are pulling from this external site via api including the login, but I need to also restrict the wordpress pages and other content based of the same login. What would be the best solution for this?
Answer: What you're after is called Single Sign On or SSO. You would essentially be bypassing WordPress' authentication methods and use those from a 3rd party. WordPress needs a local user of some kind for normal operations to work (the user_can() function for example.)
So the general gist would be something like this
- Send any request for authentication to a 3rd party who will yay or nay and return some data about the user
- if yay, check if there is a WordPress user that represents the authenticated user. If not, create one and add any meta data you might need from the third party.
- these WordPress users are like placeholders and every time you successfully authenticate, you update the meta data of the WordPress user to keep things in sync.
This is how OneLogin does it and you can poke around their WordPress plugin to get a sense of how it works. https://wordpress.org/plugins/onelogin-saml-sso/


How old is Kevin Uxbridge?

Question: In "The Survivors," we're introduced to an enigmatic and powerful being known as a Douwd. In human form, he goes by the name Kevin Uxbridge. He states that he's lived in the system for thousands of years, but is it possible to know his overall age? Perhaps from a source outside of the episode itself?
Answer: Kevin is the only Dowud we know of and, to the best of my knowledge, never appears in any other episode or in any lesser-canon work. We have nothing to go on but his word.
Comment: This is more appropriate as a comment. Also, I take statements in Star Trek to be true, unless there are good reasons to doubt them. Otherwise, you can doubt everything.
Comment: A brief list of lines in which Kevin is lying:
KEVIN: We don't know. [who attacked them]
KEVIN: We've told you time and time again, we don't know why we were spared.
KEVIN: I expected to die like all the others.
KEVIN: I will not kill.
Kevin also says that "...I am a Douwd. An immortal being of disguises and false surroundings..." and "until today, no one has known my true identity". His entire multi-millenial existence, he has been living undiscovered lies. What's more a liar's trademark than saying "Oh, got me, I was lying, but that was the /only/ thing I was lying about, I swear."
Comment: What's wrong with 'We don't know' as an answer in a case where we don't know? Additionally, since KU spent the first half of the episode *lying*, I'm not sure I agree that we can give him the benefit of the doubt.
Comment: "We don't know" by itself is an acceptable answer but a lousy one. Some more info would be helpful.
Comment: It's like when Data asks whether a lack of dimension is a dimension in of itself. Frankly, I think that answers should be fleshed out, not merely say "beats me." Kevin wasn't exactly upfront, but I'm not sure I'd say that he was blatantly lying. I could be forgetting an example of him blatantly lying, though. In a one-time character/plot situation like this, I think viewers are expected to take "final" statements as being valid. I really doubt that the writers intended this to be a mystery plot that would never be resolved. It's resolved at the end when Kevin spills his guts.

How old is Kevin Uxbridge?


Install ubuntu using GRUB2

Question: I have Deepin linux installed and now I need to install ubuntu. I don't have CD ROM , so I thought I can use GRUB2 ISO boot option. I have used the link Install Ubuntu from iso file using grub2 to boot ISO using GRUB2. I need to install the operating system. When I click Install Ubuntu icon in desktop, the installer starts. But I can't see the option where we can specify the partition. It just directly goes to installing. Even if I click install, the installer does nothing and the installation didn't start. What to do? Any ideas?
Comment: FeldAP1 - you tried to respond to an answer by adding another answer.  The way we respond is by editing your question with additional information.  Since you appear to have multiple accounts, please register one of these accounts.  Then click the contact-us link at the bottom of this page to request that your unregistered accounts are merged.  Once done, you will be able to re-edit your question with further details.  Thanks.
Answer: If you don't intend to keep Deepin Linux, an easier and standard way of doing this is to create a live USB disk. As long your computer is not old (not more than a few years old), your computer should be able to boot from the USB disk. To create a live USB disk, download UNetbootin, run it and select Ubuntu as the distribution and the version, or if you have the disk image downloaded enter the path in the text field at the bottom. Then go through the wizard and let it do its job.

Install ubuntu using GRUB2


Bitcoin security, what is wrong with my thinking?

Question: Lets assume I keep generating random public keys with their matching private keys and never use them.
Severals years later I am checking for positive match against the blockchain for all my generated public keys.
If a match is found that means someone is actually using a public key I generated in the past and for which I know the private key.
I should then be able to gain control over someone else wallet even in the case of a paper or brain wallet.
Best regards,
Answer: Thats right, if you got the private key you got access to the bitcoins on it. You dont even need to wait until someone starts using this key, you could also randomly find a key which is already in use by someone.
BUT:
Bitcoin addresses are 160 bit hashes of the 256 bit private keys, so there are 2^160 or about 1.460.000.000.000.000.000.000.000.000.000.000.000.000.000.000.000 possible addresses. You will notice thats the possibility is pretty much nil.
For more information you can read this article: http://www.miguelmoreno.net/bitcoin-address-collision/
Comment: Targeting a single address would be a waste of lives but in the case of a global multiple random targets. I was wondering how much time, computational power, and recording space would be needed to find all possible addresses.
Comment: The keys have to be generated randomly for those odds to apply.
Comment: i'm not sure, didn't benchmarked it, but as satoshi posted once, its always more efficient to mine blocks than create random address
Comment: For how long would this be true goes back to my first comment, right?
Comment: not exactly sure what you mean, but its should be true forever, after the blockreward has gone its replaced by transactions fees which should increase over time and so this should be always more efficient. And mining is done with ASICs which cant be used for creation keys so they cant just swap their power for that.


Linux mint increase cursor size beyond default max

Question: So I am using Linux mint and I have a 4k monitor so my cursor size is very very small. I have tried increasing it through Preferences->general and this worked but it is still very very small. Can this be increased through linux terminal?
Answer: Try the following where XX is the custom size entered as an integer.
<code>gsettings set org.cinnamon.desktop.interface cursor-size XX
</code>
The default small one should be something like 24.
Comment: Sorry if I did not mention this before, I am on mint linux 17 and the above command seems to do nothing. Is a reboot required?
Comment: Maybe a reload of the GUI, or at least a reload of the mouse section but I don't know what command to do that. I haven't used Mint in a while.
Comment: I have tried that, It seems that the value increases up until 50, then anything above that does not move. Is there a place I change this maximum?
Comment: It should have been able to go higher but I have no idea, sorry.
Comment: CMOS, It seems that it depends on your selected cursor theme. Some supports cursor resizing, some don't. Currently, my best choice is «redglass» from the «xcursor-themes» package, but the «ComixCursors» are nice too but smaller (i.e. you need to configure a larger value for the custom size). The «dmz-cursor-theme», «breeze-cursor-theme», «oxygen-cursor-theme» & «oxygen-cursor-theme-extra» packages also contains resizable cursors.
Answer: If anyone here wants to reduce beyond min size then use a negative number in place os XX in above command
Comment: not os it is   "of"