How to transfer photos from mac os to elementary os

Question: I have breathed new live into my 2011 mac by installing elementary os. How do I transfer photos and music files from mac os to elementary os?
I have saved all my photos and music files to an external hard drive, but when I plug the external drive in and try to open the files on elementary os - I get a message saying that I don't have permission.
Thank you in advance for your help.
Answer: I imported my photos using the gear icon on the far top right, 'Import Photos'. It sorta worked... It seemed to only get the month of April's photos for each year. Also the program seems to be crashing as soon as it loads occasionally.
Keep good backups until all this is sorted out.
Comment: Thanks Gordon- much appreciated. I will give it a try.


Facebook email blocked due to privacy settings

Question: I sent an email to someones Facebook using my Gmail address. It came back stating I was blocked by his privacy settings.  Is this because I do not use Facebook, therefore, I am not his friend so it automatically blocks me?
Answer: Facebook's email service does have two privacy options, one being Basic Filtering and the other being Strict Filtering. Your friend may have the strict filtering on, which may be causing issues. Under the privacy tab, the options for this look like the below:


Are hens and roosters the same species?

Question: I know that one is a female chicken and the other is male chicken. Are the chickens laying eggs considered the same species as those that we use for poultry meat? Or, are they different sub-species, analogous to how there are multiple breeds of dogs?
Comment: Hi @fedslaur, I have made some corrections to your spelling/grammar to make it read more easily. I have made sure to keep the nature of your question.
Answer: The main difference between a rooster and a hen is that the former is male and the latter is female. Their appearance differs in several ways [1].
A rooster also known as a cockerel or cock, is a male gallinaceous bird. The term usually refers to a male chicken [2]. The hen or the chicken (Gallus gallus domesticus) is a domesticated fowl, a subspecies of the Red Junglefowl [3].
And yes, the chickens laying eggs could be the same as the chickens that we use for poultry meat.
References:

Anjus Chiedozie. Rooster Vs. Hen on eHow.com
Wikipedia. Rooster
Wikipedia. Chicken
Answer: There are probably different breeds that are commercially preferred for egg laying versus eating.
Comment: Actually, this is partially correct.  I disagree with the downvoting.  Yes hen = female, rooster = male of same species.  But although basically all chickens can be used for meat and for eggs, there are some breeds that are better for prolific egg-laying and some for fast growth of thick meat.  See here: https://www.extension.purdue.edu/extmedia/as/as-518.pdf
Answer: Yes, they are the same species. Meat birds and layers are the same species, they have just been bred differently to produce a certain result. (Along these lines, you may wish to picture a tomato, there are many different shapes and colors. However, they are all the same thing.).
As with humans, certain chickens have certain characteristics. And to an extent "personalities".
It does appear, based on this link, that chickens are a subspecies of Red Junglefowl. However, chickens themselves do not appear to have an subspecies within them. Sorry I had to use Wikipedia.

Are hens and roosters the same species?


why  water molecules in vapor contributes to the green house effect and water condensed in drops not?

Question: I am a teacher planning a unit on climate change.  I came across this statement: "Clouds are water vapor (green house gas) and water molecules will reflect heat into space… actually clouds are condensed water and the water molecule absorbs the heat, lowering the temperature of the atmosphere around the cloud."  I don't understand why water vapor is a green house gas whereas the water molecule is not.  I also don't understand why the water molecule absorbs heat and does not reemit it....  Please explain!
Answer: A water molecule can absorb infrared radiation. Thus, water vapor can do the same. That makes it a greenhouse gas. Note that radiation that is absorbed will eventually be re-emitted. This occurs in a random direction, which is ultimately responsible for the greenhouse effect:
Heat radiation that would otherwise leave earth into outer space is absorbed and then a part of it is emitted back to earth.
The statement that water molecules are not a greenhouse gas, in the way it is presented in your short excerpt, strikes me as wrong. Both water vapor and individual water molecules absorb and emit infrared radiation.
Liquid water turns out to have a different absorption spectrum, because there certain vibrations of the water molecule are suppressed due to the bonding between individual molecules.
The claim that water just takes the eat and then does not re-emit also strikes me as bogus; if that was the case, water would get hotter and hotter and hotter, whereas in thermal equilibrium, the rate of absorption and emission must be in balance. Of course, when cold water is introduced into an otherwise warm atmosphere, the atmosphere will heat the water and cool in that process. However, the water heated in that way will still radiate in the infrared...
Answer: All water molecules do absorb infrared radiation (contributing to the greenhouse effect), but the phase of the water molecule does influence how effectively it absorbs radiation.
If you look at this graph of water's absorption coefficient: (http://t.co/SP3RyofTug)

You see that clouds are represented by the red line (water as a liquid). Water vapor is the green line (water as gas).
Per the Stefan-Boltzmann Law, the earth's average temperature of about 15C gives an average infrared emission wavelength of about 10 μmeters.
As you see in the graph, at 10 μmeters, water vapor is much less effective than liquid (cloud) at absorbing the earth's (infrared) radiation.
The issue is made more complicated, however, because of effects of cloud altitude and albedo (clouds reflecting some incident sunlight back into space).
Answer: When water molecules condense  into clouds  they release heat to the surroundings, they become bound into droplets and will need energy to become free molecules again.
A kernel is needed for the water molecules to adhere on and start forming droplets, releasing latent heat, a small ice crystal, dust, aerosols in general. That is why we observe the trails from airplanes, the supersaturated with water molecules air condenses on the trail impurities.
Maybe you should stop trusting that the article  you found this statement in is written by somebody who knows what he/she is talking about. They are probably confused with the cooling properties of clouds by reflecting incoming radiation back to space, increasing the earth's albedo.
Edit: You were asking:

why is water vapor a greenhouse gas and water molecules not?

and I edited it to the present title because the old one has an implicit contradiction : water in droplets is not a gas, whereas we talk of green house gases.
The various phases of matter, solid, liquid, gas, have different behaviours to energy absorption and emmission. As the other answer says H2O will absorb and re emit infrared whether in solid liquid or gas, BUT, it is a big but, the phase is very important. Ice and water droplets offer only a thin surface to infrared absorption and re emission  and mainly reflect incoming  electromagnetic radiation of all frequencies n from their collective molecular surface properties. In addition any heat absorbed by individual H2O could be transferred to the bulk, in contrast to the gas which re emits radially .
Answer: The radiation from the Sun is peaked in the short wavelengths (ultraviolet, visible, and near infrared). Therefore, most of the radiant energy from the Sun passes through the atmosphere, and the Earth (land and water) absorbs it. This warms the Earth. Because the Earth is in thermal equilibrium, the absorbed energy is reemitted, but it is reemitted in longer wavelengths, far infrared. The atmosphere absorbs the longer wavelength radiation more strongly. The atmosphere is thermal equilibrium, as well, so the molecules in the atmosphere reemit long wavelength radiation, but they reemit in all directions. So while the reemitted energy from the Earth has a net outward radial flow, the reemitted energy from the atmosphere goes in all directions.
So there is an energy flow radially inward (relative to the Earth) from the Sun to the Earth from short wavelength radiation and an energy flow radially outward from the reemitted long wavelength radiation. If that were it, the Earth would be in equilibrium. The absorption of the radially outward long wavelength radiation and reemission in all directions of long wavelength radiation by the atmosphere disrupts the equilibrium, and the result is the atmosphere slowly warms.
Water in gas state, along with carbon dioxide and methane, absorb long wavelength radiation, and therefore they are largely responsible for the greenhouse effect. Nitrogen and oxygen do not absorb long wavelength radiation, and therefore they do not contribute to the greenhouse effect.
Finally, the temperature of the atmosphere is rising, so it is not thermal equilibrium as a whole. However, on short time scales the molecules of the Earth (land and water) and the atmosphere are in thermal equilibrium, and that's why they reemit the radiation they absorb.


How can I connect two goals to a page test?

Question: When creating a page test in Sitecore Experience Optimization you can as test objective choose to connect either one specific goal or all your goals (trailing value/visit). Do any of you know about a possibility or work around to connect two specific goals to a page test in the Experience Optimization?
Comment: What version of Sitecore are you on?
Comment: Version: Sitecore 8.0
Answer: If you go to your page test definition in the content editor under /sitecore/system/Marketing Control Panel/Test Lab after the draft has been saved, you can see that there is a Conversion field that allows you to select multiple goals.  However, the Winner Strategy that is provided out-of-the-box, Sitecore.ContentTesting.Analytics.WinnerStrategies.TestObjectiveBasedStrategy only uses the first selection.  You would need to create a class that implements Sitecore.ContentTesting.Analytics.WinnerStrategies.IWinnerStrategy and add another Test Winner Strategyitem under /sitecore/system/Settings/Content Testing/Test Winner Strategies.  You could then select that strategy on your test.
Note that the actual implementation of the strategy could be rather complicated. It will be different depending on if you want the user to achieve both goals, if achieving either is sufficient, if you wanted to use the values assigned to the goals, etc.


How to calculate the Relative Rate Index based on data collected in tables in Cognito Forms

Question: I'm working on creating a Cognito form and need to know how to do a calculation with two calculated fields.  I've pasted a preview below to help explain it.  I want to do a calculation in the RRI column comparing the two percentages of total arrests.  I'd appreciate help on how to do this.
Comment: An image is great as supplemental information, but not everybody can see images. Your question would be much better if it had all of the needed information without the image, so that the image could act as supplemental information.
Answer: Since I am not an expert on RRI calculations, let me state a few assumptions about what you are asking:

The Arrest Rate for each ethnic group is defined as the number of arrests for that group divided by the total population of that group.
The Relative Rate Index is the ratio of arrest rates for two different ethnic groups.
In this case, let's also assume that the RRI is the ratio of arrest rates of ethnic groups specifically compared with White/Not Hispanic.
Also, let's assume that we cannot calculate the arrest rate itself since we do not have the total population, only the RRI (tricky problem).

Assuming these assumptions are correct, let's start with the algebra necessary to perform the calculation:
White Arrest Rate = # White Arrests / (Total Population * White Population %)
Ethnic Group Arrest Rate = # Ethnic Group Arrests / (Total Population * Ethnic Group Population %)
Relative Rate Index = Ethnic Group Arrest Rate / White Arrest Rate
Now, performing a bit of substitution, we have:
Relative Rate Index = (# Ethnic Group Arrests / (Total Population * Ethnic Group Population %) ) / ( # White Arrests / (Total Population * White Population %) )
Total Population cancels out, and we are left with:
Relative Rate Index = (# Ethnic Group Arrests / Ethnic Group Population %) / (# White Arrests / White Population % )
Now, switching over to Cognito Forms calculations from algebra, we can calculate both the Percent of Total Arrests and the RRI solely using information entered into the table.

First, select the option to summarize the Percent of Total City Population and Number of Arrests for Calendar Year columns, which will show the totals and make it easier to write the calculations. This also eliminates the need to capture the total number of arrests, since the table will now calculate this for us.

Enter the following calculation for the Percent of Total Arrests:
=NumberOfArrestsForCalendarYear /
Form.RacialEthnicArrestRates_NumberOfArrestsForCalendarYear_Summary

Enter the following calculation for the RRI:
=(NumberOfArrestsForCalendarYear / PercentOfTotalCityPopulation) /
(Form.RacialEthnicArrestRates.Where(RacialEthnicGroup = "White/Not Hispanic").Sum(NumberOfArrestsForCalendarYear) /
Form.RacialEthnicArrestRates.Where(RacialEthnicGroup = "White/Not Hispanic").Sum(PercentOfTotalCityPopulation) )

When the table is then filled out with information, the results are as follows:

Obviously, the RRI for White/Non-Hispanic will always be 1.00 since the numerator and denominator are the same.  Please update your post the clarify the question if my assumptions are incorrect!
Finally, here is a shared template showing the form in question, with all the necessary calculations:
https://www.cognitoforms.com/templates/shared/ThomasFamily/RelativeRateIndex
Comment: Thank you!  I will try that and I think your comment will help me simplify some of my other tables.
Comment: Your suggestions helped a lot! However, I'm running into a problem.  I created columns to calculate racial and ethic populations from the percentages and added a calculation column for arrest rate (Arrest Number/Ethnic Population * 100,000).  I should be able to get the RRI by comparing the arrest rates but I'd like the formula to work for any lable they enter.  I tried this formula  = ArrestRate2/ArrestRate2.Where(RaceEthnicity = "White/Not Hispanic") but get an error message - No applicable method 'Where' exists in type 'Decimal' at character 25.  Can you tell me what is wrong?
Comment: Please submit a support request to Cognito Forms, mention my name, and I will take a look at your form and provide specific advice!  https://www.cognitoforms.com/supportrequest/


How can I define the following function for arbitray values of the arguments?

Question: Consider the following function
a[m_, l_] = 1/Log[m/l];

with this function I define
c[NN_, r_, l_] := cc /. Solve[NN == (1/a[1/r, l] - cc), cc][[1]]

the things to keep in mind are these. The variable l is meant to be taken around 0.3 . NN is supposed to be an integer and for fixed l c will get smaller and smaller as NN-s increases. What I am interested at is to define a function that obtains for fixed l and r the value of NN that makes c smallest and positive. In order to do this I defined this
NNfun[r_, l_] := (NNN = 0; While[c[NNN, r, l] > 0, NNN++]; NNN - 1)

and it actually does the job well. Nonetheless I have a problem when I use this function to make a fit. I want to feed NNfun to another function in order to make a fit. The function I have in reality is more complicated than what I will show here, and the data I present here is not the data I have in but it is enough to make my point and to simplify the discussion. Thus, defining some random data points
data = Table[{RandomReal[], RandomReal[{-1, 0}]}, {i, 1, 30}];
dataError = Table[RandomReal[{0, 0.001}], {i, 1, 30}];

and defining the following function
fun[r_, l_] :=Sum[a[1/r, l]^n, {n, 1, NNfun[r,l]+1}]

I do a fit
NonlinearModelFit[data, fun[x, l] , {l}, x, Weights -> 1/dataError^2];
%["BestFitParameters"]
%%["EstimatedVariance"]

When I did this I obtained some numbers that made no sense to me. Eventually I think I discovered what is the issue behind. What I noticed is that
NNfun[r, l]

outputs -1 for an arbitrary value of r and l. The reason is that the While in the function does nothing for arbytray r and l so the output just takes the init value for NNN that I set which is 0 so the output is of course -1. as a consequence, when I evaluated
fun[r, l]

in the function I feed to NonlinearModelFit I actually am feeding 0, so that what I obtain is equivalent to doing
NonlinearModelFit[data, 0 , {l}, x, Weights -> 1/dataError^2];
%["BestFitParameters"]
%%["EstimatedVariance"]

So i finally arrive at my question, how can I define a function that just as NNfun above finds me the value of NN that makes c smallest and positive and that I can use in the fit function? that is that I can evaluate it for arbitrary r and l without obtaining nonsense. Or better, how can I modify my definitions so that I can use NNfun in the fit?
Answer: I have already answered on the main issue for your follow-up question.
Here I wish to note that your data have non-positive values for the ordinate, while the function is positive in the given data range 0 < x < 1:
fun[r_Real, l_Real] := Sum[a[1/r, l]^n, {n, 1, NNfun[r, l] + 1}]
Show[Plot[fun[x, .3], {x, 0, 1}], ListPlot[data], PlotRange -> All]

How could you expect to obtain a good fit for such data?


motorola droid turbo battery not charging

Question: I bought droid turbo about five months and I upgraded it to marshmallow. Unfortunately, it fell on the ground four times, then the fourth time it stopped charging. When I connect the charger, it sshows charger is connected but in the battery performance section, "it says not charging".
Answer: This had happened with my Nexus 6. As a workaroud I used to align the USB cable at an angle with the charging port. The solution however was to get the charging port repaired or replaced which stopped this problem.
I have unfortunately no information as to why it shows connected, but  not charging.


Is Quidditch considered on topic?

Question: Is Quidditch considered a sport? Are questions about Quidditch permitted here? Although some countries have established rules for Quidditch games, I am unsure whether or not it would be considered a sport on Sports SE?
Answer: There's obviously a line somewhere at which a sport is so niche that questions on it are going to be of no value to the community (e.g. "this game I made up yesterday"), but Quidditch has (in my never humble opinion) enough of a following and players that it's on-topic here. Personally, I think it's a bit silly, but that's neither here nor there.
For avoidance of doubt, I'd very strongly say only questions about the "real world" Quidditch (as you've linked to above) are on-topic. Any questions about the "Potterverse" Quidditch (with people flying around on brooms, etc) are off-topic here; they may be on-topic at Science Fiction and Fantasy.
Comment: In fact, Science Fiction and Fantasy does allow questions on the Potterverse Quidditch. I can see several well-received questions about various aspects of the in-universe game and possible rules scenarios.
Answer: We've had 5 questions with the quidditch tag, none of which are closed (or have net negative votes), which says the community hasn't viewed these questions unfavorably.
We typically take newly-explored questions on a case-by-case basis. This is found in our meta post for new users.

Is Quidditch considered on topic?


Oops, I just missed the siyum for Fast of the Firstborn

Question: I am a firstborn.  Suppose I wake up late on Erev Pesach and walk into shul right after they finish the siyum.  Can I still partake in the post-siyum meal, or am I too late?  More precisely, what are the minimal requirements for breaking the Fast of the Firstborn?
Comment: Speaking of being pedantic, I don't think not fasting for b'chorim on erev Pesach is equivalent to "breaking" a fast. If I understand correctly, the practice of firstborns fasting codeveloped with the practice of them not fasting when involved in a s'udas mitzva. This could have a ramification for the "burden of heter" and thus the answer, but I am less sure about that.
Comment: This happened to me, and I fasted. After the fact, a non-practicing rabbi (ie., he had Semichah, and had even written a Sefer, but worked professionally as an attorney) told me he believed I could have partaken of the meal, as that was the main point - ie., it is a Se'udath Mitzvah, whether I heard the words of Torah or not.
Comment: Shouldn't this question be reworded so as to not be asking for a Halachick ruling?
Answer: I heard from a rabbi that it isn't strictly necessary to actually hear the siyum. The person who did the siyum celebrates by throwing a party and invites people to join him. All those that partake in the party are exempt from fasting.
In fact, some people mistakenly believe that hearing the siyum is all that's required, and subsequently go home to eat. This (according to the aforementioned rabbi) is a mistake. They must partake of the meal given at the site which celebrates the siyum.
Comment: In the comment thread on his recent Hirhurim post on the topic of this fast (http://hirhurim.blogspot.com/2010/03/erev-pesach-fast-of-firstborn.html), I asked R' Ari Enkin if he'd seen these ideas in the sources. He responded: "This is a very, very b'dieved position which is not endorsed by too many authorities. Everyone agrees that one must hear the siyum, lechatchila."
Comment: I've been at a (rabbinically endorsed) siyum where they didn't even serve food...when I asked they said you should eat sooner rather than later.
Comment: This happened to me, and I fasted. After the fact, a non-practicing rabbi (ie., he had Semichah, and had even written a Sefer, but worked professionally as an attorney) told me he believed I could have partaken of the meal, as that was the main point - ie., it is a Se'udath Mitzvah, whether I heard the words of Torah or not.
Answer: The Gra, the shulchan aruch, and the mishnah berurah, all say you should fast.
The Gra was particularly insistent that healthy adult firstborn males should NOT get out of fasting on Erev Pesach by attending a siyum, but should actually fast!  However, even the Gra conceded that, when Pesach starts on shabbos or motze shabbos, and the fast is pushed ahead to Thursday, since it is no longer done on Erev Pesach, one may attend a siyum to avoid the fast.
Wikipedia has an unusually erudite exposition on the fast of the firstborn, including a whole section on when/how to break it.
http://en.wikipedia.org/wiki/Fast_of_the_Firstborn
If you miss the siyum, and you're otherwise healthy, just fast.  After kiddush on the first cup of wine at the seder, you can have as much water and other food (except matzah and matzah meal products) as you like.
Comment: Do you have a source for this Gra?
Comment: Do you have a source for your final statement? I imagine it ought to at least be limited by the requirement to leave room for the things you eat as Mitzvot and the Afikomen.
Comment: This is not an answer! Lots of interesting ideas and thoughts and opinions, but it didn't answer the question.
Comment: Sorry guys.  Both answers I received orally from one of my mentors and teachers.  (Yes, I am a bechor, and yes, I have fasted on taanis bechoros).
Comment: @DannySchoemann, you mean except for the first sentence?
Comment: @SethJ - that's not an answer to this question, which is discussing somebody who prefers not to follow the _Gra, the shulchan aruch, and the mishnah berurah_ (and when I have time, I plan on double checking that suspicious info.)
Answer: The main obligation is to give charity (and thereby "redeem the fast"). The siyum itself is really just extra, and in fact, as noted in the answers above, the siyum doesn't really "work" since most people do not actually join in a celebratory meal afterward. So the minimal requirement is charity. This was explained by one of the poskei hador in the US, R. Henkin
http://hebrewbooks.org/pdfpager.aspx?req=22080&st=&pgnum=61
Answer: From Wikipedia:

If a firstborn attending a siyum does not hear the completion of the tractate, or if he does not understand what he hears, or if he is in the shiva period of mourning and is thus forbidden from listening to the Torah material being taught, some authorities rule that subsequent eating would not qualify as a seudat mitzvah and he would therefore be forbidden to break his fast (Ben Ish Chai 1:96:25; Rabbi Shlomo Yosef Elyashiv, Siddur Pesach K'hilchaso, p. 168; Rabbi Ovadia Yosef, Chazon Ovadiah, p. 99).
Other authorities allow a firstborn to break his fast under such circumstances (Minchas Yitzchak 9:45; Teshuvos V'hanhagos 1:300, 2:210 in the name of Rabbi Yaakov Yisrael Kanievsky). The Minchas Yitzchak (ibid.) suggests that a firstborn in such a position should at least try to contribute to the siyum in some way, such as by sponsoring or helping to prepare the meal.
In order to break one's fast on a seudat mitzvah, many authorities rule that one must partake of at least a kotevet of food (around 1.5 to 2 oz.) or a melo lugmav of liquid (at least around 1.7 oz.) at the seudah (Minchas Yitzchak, ibid.; Chazon Ovadiah, ibid.; Teshuvos V'hanhagos, ibid.).
Other authorities rule that a firstborn need not eat anything at the siyum itself, and that he may break his fast anytime after the siyum (Siddur Pesach K'hilchaso, ibid; Rabbi Yehoshua Menachem Mendel Ehrenberg, Devar Yehoshua 2:81).
...
Additionally, the Mordechai (Pesachim 107) quotes the ruling of his father-in-law Rabbeinu Yechiel that firstborns need not fast at all on the day before Passover; firstborns need only limit their diet to snacks. (The Bigdei Yesha commentary suggests the rationale behind this ruling was to avoid holding a fast during the month of Nisan, which is generally prohibited.) The Mishnah Berurah states that it is appropriate for a weak individual to follow this ruling.

The opinion of R' Tz'vi Pesach Frank, regarding if someone made a siyum and did not fast on a Thursday adjusted fast, may also be of interest:

The above halakhic quandary is avoided completely if a firstborn fasts the entire day on Thursday. However, Rabbi Feinstein makes no mention of this requirement. In order for a firstborn (who eats on Thursday) to comply with the ruling of the Rema, the Piskei T'shuvot suggests participating in a second siyum on Friday, while Rabbi Tzvi Pesach Frank suggests partaking on Friday of leftovers from the previous day's siyum.


"Product with specified super products SKU not found in rows:..." when reimporting just exported products to empty database

Question: I exported all my single and configurable products to .csv and emptied my database of all products afterwards. I am now trying to reimport those same products using the just created .csv file. Unfortunately, I am getting the message:
Product with specified super products SKU not found in rows:...

followed by the list of skus, and followed by another message below:
Orphan rows that will be skipped due default row errors in rows

and then another list of skus. What does this mean, considering I have JUST created that same .csv from the currently working and functioning Magento? I also tried to completely empty the database from products and making only one configurable product with one associated simple product, with the same result (the error message Product with specified super products SKU not found in rows)  What can I do to mend this?
Answer: You must import the simple product first and the configurable product after that. It sounds like the simple product cannot be find when the configurable product is imported.


How Class Lookup happens in Android ART?

Question: As per my understanding of AOT( Ahead of Time ) compilation in ART, dex files are converted into native codes at the time of installation. Does that mean that the dex files are never referred after the installation? If this is so, then why there is the entry for dex file references in OAT files.
Answer: From the Google IO video on ART the speaker states that the DEX files are kept around for class loading and debugging. https://youtu.be/EBlTzQsUoOw?t=9m20s
Comment: so how does the class loading happens using these dex files, do you have any idea?


What is the advantage of shuffling data in train-test split?

Question: I have been taking an online course on data science, and was recently introduced the ideas of overfitting and underfitting, that is splitting the dataset we have into two parts into training(80%-90%) and testing(10%-20%) dataset. The instructor says we prefer to shuffle our data before the split, what is the reason for this? Isnt the whole idea of the approach of Splitting into Testing/Training Set is based on the assumption, that the observations are Independent and identically distributed random variables. Then there is no meaning to shuffling our data. Did i get it correct?
Answer: It may depend on where the data came from and how it was exported. It's not uncommon that real world data is sorted in some manner. For example it could be sorted by:

user id
timestamp of the observation
outcome of interest

In each of these cases if you do a test/train split on the data without shuffling then you may have a different data distribution in your splits! For example if the data is sorted by user_id, then most users will appear in either test or training set, but not both.
How much this matters probably depends on how you intend to use your model. For example in lots of real world ML applications you train on historical data, and make predictions on future unseen data. In that case having the data sorted by timestamp before creating your splits might actually be desirable, since it matches the way you'll apply the model in the real world.
Answer: In general, splits are random, (e.g. train_test_split) which is equivalent to shuffling and selecting the first X % of the data. When the splitting is random, you don't have to shuffle it beforehand.
If you don't split randomly, your train and test splits might end up being biased. For example, if you have 100 samples with two classes and your first 80 samples are from class 1, and remaining are from class 0, a 80/20 split would leave all class 0's in the training set and all class 1's in the test set. This way, in the training, you wouldn't see any examples from class 1 and cannot learn.
Sometimes, it's even helpful to shuffle after the splits, e.g. in neural nets, to keep the parameters inside a reasonable subset.


Why does a bigger sensor have better dynamic range?

Question: I already understand all the theory behind how a bigger sensor leads to better control of depth of field, and lower noise. But I've yet to find a place that can explain why a bigger sensor gives you a bigger dynamic range?
Comment: JoanneC: that's true for dynamic range **in good light**. At ISO100 the APS-C Pentax K5 beats the full frame Canon *by over two stops*, however at ISO800 and above the full frame Canon is ahead, and in really low light the gap is over a stop, which is about what you'd expect from the sensor area advantage.
Comment: AFAIK, 5 of the top 10 dynamic range cameras on DxOMark are APS-C sensor cameras and all of them are 35mm form factor and no medium format is there. So, the opening premise of the question isn't really true.
Comment: Does this answer your question: [What's the relation between sensor size and image quality (noise, dynamic range)?](http://photo.stackexchange.com/questions/26001/whats-the-relation-between-sensor-size-and-image-quality-noise-dynamic-range)? Also see [What is the dynamic range comparison between SLR, DSLR, and point & shoot?](http://photo.stackexchange.com/questions/4389/what-is-the-dynamic-range-comparison-between-slr-dslr-and-point-shoot) and also http://photo.stackexchange.com/questions/7616/what-is-dynamic-range-and-how-is-it-important-in-photography
Comment: JoanneC: APS-C and 35mm are different sizes. A sensor cannot be both.
Answer: The size of the sensor does not matter, it is the size of the pixel. Having that said, bigger sensors like in full frame cameras tend to have bigger pixels.
You can estimate the size of the pixel by taking the size of the sensor and divide it by the number of pixels. This calculation is not accurate because most sensors have gaps between the pixels and these gaps differ in size. That is why I'm saying "estimate".
Now, think of a pixel in the sensor as a box and photons as balls. The bigger the box, the more balls it can contain.
Assuming we have box A and B. Box A can contain 256 balls and box B can contain 512 balls.
Now lets arrange a box matrix of A type and throw a lot of balls in the air. We want gather some statistics of where the balls fell.
In the middle one of the boxes contains 256 balls and in the edges the boxes contains ~20 balls. We cannot know if in the middle only 256 balls fell or more.
Our measure is limited to maximum for 256 balls.
Now lets repeat this experiment but now with boxes of type B. Now we can see that in the middle the box contains 347 balls and on the edges the boxes contains ~20 balls.
Our measure is far more accurate. That's exactly what happens with the photons hitting the sensor. Bigger surface can contain more photons and can measure a larger dynamic range. In our example the dynamic range is twice as big in the bigger box.
If the pixel is full of photons the translation to color will be a fully saturated color but with a larger pixel surface we will get a better result, thus, improved dynamic range.
Here is a picture that can demonstrate my explanation:

For deeper explanation you may want to check this article:
Dynamic_Range
Comment: This answer is a good start, however it is missing a critical factor: Electronic noise. Yes, it is true that you have improved dynamic range (and less photon shot noise) with larger pixels. It should be noted, however, that gains made with larger pixels can be LOST due to electronic noise in the sensor circuit, as well as in the readout and conversion circuitry. Theoretically, the Canon 1D X should have more dynamic range than the Nikon D800, yet the D800 has a full two stops more DR. Why? The D800 has FAR less electronic noise (~3e-) than the 1D X (~36e-).
Comment: Nice, I'll now up vote.
Comment: Good explanation of the theory but completely ignores the practice!
Comment: The article you linked is really, really great! Compliments
Answer: Considering ideal sensors where photon noise is the only concern then the larger the sensor the greater the dynamic range. Dynamic range is the difference between the point at which the sensor becomes saturated and the point at which any detail is lost to noise in the shadows.
A larger sensor will either have larger pixels, or more pixels. Larger pixels mean a greater capacity to store charge (all else being equal) and more light being captured per pixel hence less light in the shadows, hence greater dynamic range. More pixels means the similar noise per pixel but more pixels to average over to reduce shadow noise, and hence increase dynamic range.
In reality there are other sources of noise, namely read noise, where the analogue signal produced by the photosites picks up noise prior to being digitized. This can have an effect on dynamic range that is far stronger than differences in sensor size. Low intensity signals from dark areas of the image are particularly sensitive to read noise hence the large impact on DR.
New technology (shortening the path from sensor to ADC, sending the signal twice and comparing the results) can virtually eliminate read noise this enables APS-C sensors such as the Sony Exmor to exceed the dynamic range of Canon's 2.5 times larger full frame sensors by almost an order of magnitude!
It is also necessary to distinguish between dynamic range in good light and dynamic range in poor light. The former is determined mainly by read noise, hence a small sensor can excel provided it has low read noise and a decent enough well depth. The latter is dominated by photon noise (raising the ISO in low light amplifies photon noise but not read noise) hence larger sensors tend to perform better here. Again not every sensor follows the trend.
Comment: The benefit of Sony Exmor is that it is digital readout. The signal is only analog so long as the charge remains in the pixels. Upon read, on-die column-parallel ADC immediately converts the analog charge of each pixel into a digital unit. High frequency components (clock, pll, etc.) are placed elsewhere on the die to eliminate high frequency noise introduction in the ADC circuitry. The image signal is not read twice...a "reset read" is performed when the sensor is reset to accumulate digital CDS as a "negative result", which is then applied to the "image read" upon exposure.
Comment: Per-pixel CDS was eliminated. I don't even think each pixel has an amplifier, as with near-noiseless output, all ISO settings can be achieved with digital amplification. Analog pixel charge is converted immediately to a digital unit, and from that point on error-corrected information transfer of digital information is utilized throughout the rest of the image processing pipeline. That eliminates the chance for contamination of the analog signal by interference of any kind as early as possible.
Comment: Am I correct in saying that, given the same read noise (technology etc) the larger sensor with bigger pixels will have less photon noise and thus better dynamic range because of increase latitude between the lowest charge and saturation point?
Comment: @erotsppa The surface area used to calculate each final pixel is all that matters. If you have 4 tiny photosites and 1 large photosize of the same size, the average of the 4 will be almost exactly the same as the large single photosite. Having more photosites in the same surface area just increases the sampling frequency; each will have worse characteristics by itself but if the photo is scaled down to the same pixel density as if they were all just one big photosite it would look no different. This is why cell phone cameras look fine on phone screens and poor on computer screens.
Answer: There is no reason that a bigger sensor can give a bigger dynamic range or lower noise other than more surface area per pixel, however full frame cameras tend to be higher end units and therefore tend to have better sensors.
Note that there is no reason that a lower resolution, smaller sensor couldn't have better noise and dynamic range performance if made at a similar quality to a full frame sensor.  The number of pixels per inch on the sensors surface and the quality of the sensor are the bits that matter.
Answer: The example with the boxes is very much true and explains why bigger sensors have a large dynamic range. The smaller the pixel the less photoelectron it can store (the maximum number of photoelectrons that can be stored is called full well capacity).By shrinking the sensor we can reach the situation that only few electrons can be stored resulting in black-and-white image (no shades of gray!(:).
So there is no doubt that larger sensor has higher dynamic range if everything else is the same.
The question is, can you increase the dynamic range by lowering resolution?
I know that one can do it with scientific CCD cameras (I personally did it). But can you do the same with consumer cameras and with CMOS? I assume yeas if you can bind 2x2 pixels into one (effectively reducing resolution 4 times).
Answer: According to my research even pixel size do not matter , the box theory is applicabe for the lighting conditions as larger pixels collect more light it will surely have an edge in low light( common sense) but the sensor technology is the key factor in dynamic range, as dynamic range is the ability of the sensor to retain retails in highlights and shadows. For instance the dynamic range of a newer sensor small or big fan be better than the dynamic range of a older full frame sensor


Can ping flooding attacks still be implemented in a IPv6 network?

Question: Can ping flooding attacks still be implemented in a IPv6 network? And what could be a good way to simulate such an attack?
Answer: Yes, ping floods can still be implemented in IPv6 networks. They operate in largely the same manner they do in IPv4 networks. Although IPv6 is a "new" protocol (it was conceived in 1998), there's still plenty of attack vectors to worry about, such as the Neighbor Discovery Protocol and the massive address space IPv6 occupies.
As far as simulating attacks on an IPv6 network, I would set up a virtual network with your chosen OS and virtualization software, and use a suite like THC-IPv6 to attack the network. It is a suite used for attacking IPv6 networks. It's got all kinds of goodies. Smurf6 may be of interest to you.
If you want to do some reading on IPv6 security, this paper is full of good stuff.


How can I get a specific Floor in my Tower?

Question: I really really want a specific floor (Glass Studio) in my Tiny Tower.  How does the game decide which exact business will go into the "Creative" floor?  Do I have to meet requirements (such as tower height) to unlock certain floors?
Answer: With the recent release of version 2.0 (July 26, 2012 for iOS devices), you can pay Tower Bux to build a specific floor from all of the not-yet-built floors.
You can't do this while a floor is under construction. Once you have built an empty floor (using coins), you tap on the floor and choose "Choose Specific Floor" from below all of the "Random [Floor type]" buttons.
Comment: You cant choose all business types when choosing a specific floor though
Answer: The floors are completely random. There is no way to make sure you get a certain floor in a particular category. You just have to wait and hope it shows up when you build.
Comment: Building a new floor costs coins, but deleting the business or housing on an additional floor costs only the Construction time.  Since I was low on coins, but had time, I just deleted an existing business and built a new Creative floor a few times.  Eventually I got what I needed!
Comment: What are the consequences of deleting an existing business, and Constructing a new Creative floor in its place?
Comment: You lose that building, obviously, and have to pay (and wait for) a new floor.


Is it possible to associate goal triggering on button click without code?

Question: In sitecore DMS is there any way to associate goal triggering on button click without code , i read some blogs which are giving info regarding how to associate item or pdf to trigger goal . So is it possible to trigger goal on button click without any coding means just configuring it within CMS?
Comment: You can register it with JS and an API. But that will require you to create the API with code. https://sitecore.stackexchange.com/questions/603/can-i-register-an-event-or-goal-through-an-api-from-javascript
Answer: No.
You can only associate goals to items. Described here: Associate a goal with an item
But I would add; you're likely also thinking about this wrong. The goal you have, is not "the user presses the button". The real goal is "the user sees the content of my target page" - the page targeted by your Call to Action.
So you should proceed to associate your desired goal, with the item your "Go" button is linking to.
Further
Sitecore marketing philosophy is "value driven engagement". So you associate events and happenings on your site by value. Not by click, as clicks in and on their own, mean so very little.
Answer: Honestly I was looking into this myself too. And whereas Mark says that this is not possible that is (for as far as I am aware) still true.
However, I don't agree that you should look whether or not the visitor "looks at the content of my target page" since that is not true in a large number of cases.

adding an item to a Basket
marking something as a Favorite
Bookmarking pages
Subitting a (custom?) form
Downloading a whitepaper

...
Obviously, using Sitecore's Xconnect and SDK you could register these triggered goals after most of these actions.
However, Sitecore should be an enablement platform. Enabling your editor and marketer to perform these tasks themselves.
Looking at the below link: https://doc.sitecore.net/sitecore_experience_platform/80/digital_marketing/federated_experience_manager/using_fxm/apply_a_click_action_to_a_component_in_the_fxm Sitecore actually already allows you to perform this functionality
One would expect you to be able to have this in Sitecore directly as well.
Answer: Yes, it is possible. But it requires workarounds. There are 2 possible ways.

Use Sitecore.SBOS.LinkManager module from GitHub. It will allow you to set goal/pageevent/campaign on external links. If you need to do it on internal link then you need to add it as external link, using URL, not item. Then you will be able to add goal/pageevent/campaing. Module was developed on Sitecore 8.2. But I don't see any restrictions, why it could not work on other versions. Also, I think that this module could be easily extended for internal links.
Use ?sc_trk Sitecore get parameter. Again, it will work only with "external" links to Sitecore pages. It is present in Sitecore 6.5 documentation, so should be supported since that version.

P.S. I have checked and both workarounds work fine on Sitecore 9.3.
Answer: Similar to @Anton's example, you can achieve the same result with a Tag Manager solution.
Summary

Add an API to receive requests
Add Tag Manager
Content Authors can then create events/goals and trigger them on any action available with the Tag Manager

Sitecore GTM (API)
https://github.com/kazimnami/Sitecore.Commerce.ProductEngagement
This repo, most recently updated by Rob Earlam, provides an implementation for an API that receives requests from Google Tag Manager events. It is focused on Sitecore Commerce and  Habitat, but the implementation is generic enough to be adapted to any project.
Use Case
Once in place, content authors are able to create new events in Sitecore and publish them. Next, they grab the ID of the event and switch over to GTM. From GTM, they set up event triggers that will send a request to the API layer.
There are many trigger types available: https://support.google.com/tagmanager/topic/7679108

click
element visible
scroll depth
timer

The syntax for the goal/event registration is as follows:
<code><script>
AjaxAnalyticsGTM.RegisterProductGoal("{EVENT GUID}");
</script>
</code>
While these steps are not out-of-the-box, with a little work up front, all actions can be configured by content authors.
Answer: Yes. It is possible if the form (which has the submit button) is created using Sitecore Forms.
One of the out-of-the-box submit actions that Sitecore offers is the Trigger Goal. We can choose this submit action and then select the goal that we want to trigger on this button click.
Check my detailed answer here with step-by-step screenshots - https://sitecore.stackexchange.com/a/25903/4515
Refer the below link for knowing all the available Submit actions OOTB : https://doc.sitecore.com/users/90/sitecore-experience-platform/en/working-with-submit-actions.html


How do I shuffle cards for a card game?

Question: I am trying to develop an card game for Android Can anyone suggest me how to write code for effectively shuffling the playing cards?
Answer: Card shuffling is an algorithm which is easy to write intuitively, and get entirely wrong by doing so.  There's a good reference for implementing card shuffling correctly on Wikipedia.  What I'm presenting here is a very slightly simplified version of the algorithm covered on that page under The modern algorithm.
Here's the basic idea, in plain english:
Consider a deck of cards.  For this discussion, you can have any number of cards in the deck, and they may start in any order.
We're going to be talking about "position" in the deck, where "position" is how many cards are higher in the deck than the card in that position.  For example, the card on top of the deck is at position 0, the card beneath that is at position 1 (because there is 1 card higher than it -- the top card), and in a standard 52-card deck, the bottom card is at position 51, as 51 cards are higher than it in the deck.
Now, we consider each position in the deck, one at a time, starting from the bottom, and working our way up to the top.
For each position, we randomly select one of the cards which is at that position or at a lower-numbered position (remember, the top of the deck is 0, and we're working our way up from the bottom of the deck, so for each position, you're effectively picking up all the cards at and above that position and randomly picking one of those cards).
When we have made the random selection, we swap the card at the position we're currently considering with the card we randomly selected.  If we randomly selected the card which was already in that position, then no swap is performed.
After swapping (or not swapping, if we randomly selected the card which was already in the position we were considering), we move on to the next position in the deck and continue.
In pseudocode, with n being the number of cards in the deck, and a being an array representing the deck, the algorithm looks like this:
for each i in [n .. 1] do
     j ← random integer in [ 0 .. i ]
     exchange a[j] and a[i]

Comment: The algorithm is also nicely visualized here: http://bost.ocks.org/mike/algorithms/#shuffling
Answer: You first define a sequence of all the cards you want to shuffle:
List<Card> shuffled = new ArrayList<Card>();
shuffled.addAll(allCards);

Then you walk through every position in the sequence and assign it a card randomly.
Random random = new Random();
for (int i = shuffled.size() - 1; i >= 0; i--) {
    int j = random.nextInt(i + 1);

    /* swap cards i,j */
    Card card = shuffled.get(i);
    shuffled.set(i, shuffled.get(j));
    shufflet.set(j, card);
}

Now shuffled is a random sequence of all of your cards.
Comment: this is known as Knuth's shuffle: http://en.wikipedia.org/wiki/Knuth_shuffle
Answer: I'd like to chime in and mention "format preserving encryption" as a method for shuffling cards in a game.
Essentially what you'd have is an encryption algorithm that takes in a value 0 to 51, and a key (shuffle seed) and spits out a value 0 to 51.  Since encryption is reversible by definition that means any 2 input numbers cannot encrypt to the same output number, which means if you encrypted 0 to 51, you'd get 0 to 51 as output in a different order.  In other words you have your shuffle and don't even need to do any actual shuffling.
In this case you'd have to make or find an encryption algorithm that took in 6 bits and spit out 6 bits (0-63).  To draw the next card from the deck you'd have an index variable which started at zero, you'd encrypt that index, increment the index and look at the value that came out of the cipher. If the value is >= 52, you ignore it and generate a new number (and increment the index again of course).  Since encrypting 0-63 will result in 0-63 as output, in a different order, you are just ignoring any value that comes out >= 52 so that you have your algorithm that takes in 0-51 and spits out 0-51.
To reshuffle the deck, set the index back to zero and change the encryption key (shuffle seed).
Your algorithm doesn't need to be cryptographic quality (and it shouldn't be, cause that would be computationally expensive!).  One really good way to come up with a custom sized encryption algorithm like this would be to use a feistel network, which lets you customize size and quality depending on your needs.  For the round function of the feistel network, I'd recommend something like murmurhash3 because it's fast and has a good avalanche effect, which would make the shuffles appear well randomized.
Check out my blog post for even more detailed info and source code:
http://blog.demofox.org/2013/07/06/fast-lightweight-random-shuffle-functionality-fixed/
Comment: Good point Lars, updated with more info so that a reader can at least look for more info on all the specific components of a solution to card shuffling using format preserving encryption.  Thanks!
Comment: This answer as it currently is phrased doesn't help much when the URL inevitably falls off the surface of the Internet. Consider elaborating in the answer on the salient points of the linked article, so that the answer can stand on its own.
Answer: The java 1.5 enum tutorial has a interesting way to implement a deck of cards, building up the deck, shuffling and dealing. All very simple using enums and Collections
public class Card {
    public enum Rank { DEUCE, THREE, FOUR, FIVE, SIX,
        SEVEN, EIGHT, NINE, TEN, JACK, QUEEN, KING, ACE }

    public enum Suit { CLUBS, DIAMONDS, HEARTS, SPADES }

    private final Rank rank;
    private final Suit suit;
    private Card(Rank rank, Suit suit) {
        this.rank = rank;
        this.suit = suit;
    }

    public Rank rank() { return rank; }
    public Suit suit() { return suit; }
    public String toString() { return rank + " of " + suit; }

    private static final List<Card> protoDeck = new ArrayList<Card>();

    // Initialize prototype deck
    static {
        for (Suit suit : Suit.values())
            for (Rank rank : Rank.values())
                protoDeck.add(new Card(rank, suit));
    }

    public static ArrayList<Card> newDeck() {
        return new ArrayList<Card>(protoDeck); // Return copy of prototype deck
    }
}

And the class to manage the deck.
public class Deal {
    public static void main(String args[]) {
        int numHands = Integer.parseInt(args[0]);
        int cardsPerHand = Integer.parseInt(args[1]);
        List<Card> deck  = Card.newDeck();
        Collections.shuffle(deck);
        for (int i=0; i < numHands; i++)
            System.out.println(deal(deck, cardsPerHand));
    }

    public static ArrayList<Card> deal(List<Card> deck, int n) {
         int deckSize = deck.size();
         List<Card> handView = deck.subList(deckSize-n, deckSize);
         ArrayList<Card> hand = new ArrayList<Card>(handView);
         handView.clear();
         return hand;
     }
}

Answer: Simply use a function like itertools like there on Python . I am not aware of the name of the same function in Java try ".http://code.google.com/p/neoitertools/"
Find out all the permutations of the object called "cards"
Answer:     ArrayList deckCards = new ArrayList<Card>();
    //add your cards to the deck
    deckCards.add(card1);
    deckCards.add(card2);
    deckCards.add(card3);
    ....
    //shuffle the array list
    Collections.shuffle(deckCards);

Comment: Code-only answers are discouraged.

How do I shuffle cards for a card game?


Does over- or underexposed give the most life-like post-edit results?

Question: I have a Canon 600D with a 70-200 f/4 L lens, and I often photograph people outside in bright daylight. Now, I always shoot RAW and do some post-editing in Photoshop/Lightroom, but I'm not sure how to get the best most lifelike result? With under or overexposed? This, of course, is if I can't get it correct the first time!
Comment: *This, of course, is if I can't get it perfect the first time* - you might want to make that clearer in your title.
Comment: If you are shooting RAW already, and are concerned with most life-like results, worry about the white balance setting in post. Also, if you don't already have a lens hood for the 70-200/4, strongly consider getting one. The 70-200 is good, but flare always risks reducing image quality no matter how good the lens is, and a hood greatly reduces the risk of flare.
Answer: Overexposed areas have a sharp cut-off when the maximum pixel value is reached. You have a completely white area if this happens in all colour channels. There is nothing you can do in post to recover information in those areas.
In contrast, underexposed areas retain information, but when you brighten them, you amplify the noise, too, and with less bits to record details, you loose gradation.
So, in conclusion, a light underexposure allows to still process the image to an acceptable result with some noise reduction, while blown out whites are lost for good.
Still, the best course of action is to expose as bright as one can get away with without blowing out any important highlights, a technique called "Expose To The Right (ETTR)".
Answer: Neither. Underexposure means that you did not deliver enough light and you are losing information in shadows. Overexposure means that you delivered too much light and losing information in highlights. Both are wrong. Expose correctly. Check your histogram or allow the blinking under/over exposure alarm in the preview to see how are you doing. Correct if necessary.
Shooting people in bright light is fine, but if you combine dark shadows and very bright areas (like sunny day at noon), you will have problems with tonal range of your pictures. Try to avoid extremely high contrast situations for normal shooting. Find better location, better time of a day or use some of the techniques that equalize the contrast (reflector, flash, better selected angle to the sun...)
Answer: When the composition requires detail from shadows I would suggest exposing to the right on the histogram making sure not to overexpose and blow the bright areas on the photo as that would mean losing information in the shot.
Taking photos in raw with some post processing skills you will be able to get details from the shadows. But harsh bright sunlight will always screw with the contrasts so consider exposure bracketing and/or dual-iso (magic lantern - warning might brick your camera and void warranty).
Answer:
I am not sure how to get the best most lifelike result?

If by "more lifelike" you mean you want to avoid dark shadows and squinting subjects and instead capture smoother gradations, softer shadows, and more natural facial expressions, then stop shooting in bright sunlight and instead move your subjects to areas with open shade.
Hard light means light from a small or distant source like the sun; it's very directional and casts a strong shadow. Soft light means light from a large source, like a large area of open sky; soft light comes from many directions, so the shadows are much softer and more pleasing, and it's also much more comfortable.
Areas shaded by large objects like buildings provide plenty of soft light without the problems caused by very bright, very hard direct sunlight. Open shade means areas where the sky overhead isn't blocked, but the sun doesn't shine directly on your subject.
Shooting on cloudy/overcast days is similar to shooting in open shade: clouds block the direct sun and instead give you large light sources with soft shadows.
Answer: When taking the picture you should use the expose to the right (ETTR) method as explained in ths' answer. When doing the post processing work you can then decide to reduce the exposure to let the scene look more naturally. E.g. if you take a picture at night, you can usually crank up the exposure to make it look like daytime. This may be what you want, but perhaps you want to show how the scene actually looked like to you which will then be a lot darker than what the picture looks like. As explained in the other answers, it's then still advantageous to expose for as long as possible and then reduce the exposure in post processing as that will reduce the noise relative to taking the picture with the exposure you want straight away.


I'm a Kenyan citizen with an expired US visa, who wishes to fly to Kenya without arranging transit visas. How can I do that?

Question: I am a Kenyan citizen and my US visas expired in December 2015. I was going back home to Kenya through London, and at Boston Logan airport I was refused to be allowed to board the plane as they said I can't transit through London with an expired US visa. I am going back home to Kenya to get them renewed, so what countries can I transit through now that London is out? I need to travel as soon as possible and really don't know what to do.
Comment: You can also fly direct from the US to Addis Ababa, where Kenyan citizens do not require a visa.
Comment: You are actually supposed to be able to transit through London with an expired US visa if you're returning from the US. Maybe there is a time limit on the expiration, though.  Direct flights from the US to Kenya are also expected to begin soon.
Comment: You can only transit through the UK if you entered the US on a valid visa less than six months ago. Had this discussion with BA. See here: http://travel.stackexchange.com/questions/34106/is-there-a-way-to-find-out-if-i-need-a-transit-visa-for-a-layover-in-the-uk
Answer: One option might be to transit through Dubai. From Visa policy of the United Arab Emirates:

Passengers on all international airlines may enter the United Arab Emirates for 96 hours after obtaining a transit visa at the airport. The time difference between the two flights must be over 8 hours and the passenger must continue to a third destination. Passengers also must have a hotel booking. 1

There are direct flights from Boston to Dubai, and from Dubai to Nairobi.
Comment: Emirates is what everyone is suggesting, so is it assured that i can take a flight from boston to dubai and then nairobi from there without any issues?
Comment: @miralpatel: We can't guarantee success. However, Dubai has a fairly relaxed transit visa policy. From the information I can find (eg. http://www.emirates.com/english/plan_book/essential_information/visa_passport_information/find_visa_requirements/find_visa_requirements.aspx) it looks like there is either TWOV where you don't leave the airport, or a short term visitor visa which requires a hotel. In your situation I would book through a travel agent and ask them to help confirm your eligibility.
Answer: Turkey also lets people transit through without a previously arranged visa.
Comment: So something like a turkish airlines should work well right, like from boston to turkey and from there to nairobi?
Comment: I've had friends in your situation do that.
Answer: You can transit through the Schengen area without a visa provided you don't need to change airports. There are several possible itineraries which transit through various points in Schengen.
You can also transit through Doha, Qatar (ask BA if they can book this for you because it's on an alliance partner Qatar Airways); Dubai, UAE; Istanbul, Turkey; and almost anywhere else except the UK.
Comment: @miralpatel Yes, this includes Amsterdam and Frankfurt. https://en.wikipedia.org/wiki/Schengen_Area
Comment: Thank You but i was confused which countries or cities fall in the Schengen, so does it include places like amsterdam and frankfurt?
Comment: @fkraiem sorry, thanks for catching me in my confusion.  Comment deleted.
Comment: SO UAE shouldn't cause any trouble with my expired US visa? @phoog I am a Kenyan Citizen(i have dual citizenship with India) but yeah kenyan passport with expired US visa
Comment: @phoog nvm u just answered it
Comment: So i have decided to travel with emirates, can anyone confirm on whether or not i can go through dubai without any issues whatsoever.
Comment: @miralpatel See Greg Hewgill's answer.


Soluble compounds to absorb radio-frequency electromagnetic radiation

Question: Are there any soluble compounds capable of absorbing radio-frequency or long microwave  radio-frequency electromagnetic radiation? I have noted that metals are often used to absorb these signals, but I cannot find any absorption spectra for radio/long microwave wavelengths.
Answer: Of course! Salt water is effective, because it is an ionic solution. Submarines and SCUBA divers cannot use radio-frequency (RF) communication over any distance because of that issue. Very high power, very-low-frequency (VLF) land-based transmitters can penetrate to perhaps 20 meters depth to subs, but salt water is essentially opaque to RF and microwaves.


OOTB item Level permission in SharePoint 2010

Question: In my SharePoint Site I have 5 group with all contribute permission and need restrict data so that data not related to particular group not get exposed via any means to other groups. Can any one suggest any solution or item level permission will work out?  Implementing item level permission will cause performance issue in long run of application.
Answer: Create five lists/libraries and break the permissions. Remove the groups that should not have any access. Or am I missing something?


Steps to add result types to Advanced Search page and successfully get hits

Question: I have advanced search working fine for the 4 main result types that are there. How do i have it find txt file types.  I added the new result type to the result type drop down , I see it and i select it but the txt file is not returned when i select search button.  the search is showing its looking for ALL(*)(FileExtension="txt") so that looks right...  any ideas what I am doing wrong?
Comment: Oh I think i know the issue.  The query that I have does not include txt files.  I feel stupid.  I will update the query and if it works then I answered my own question.
Answer: I had created a result source a while back and i did not include the return of txt file as part of the query.  I just assumed I was returning txt files. Even though I added the result type for txt in the drop down of my advanced search web part I still would not get any hits because the result source query didn't include txt.  All is working now that i updated the result source query that I am using to include txt files.


In what animal species is the sex ratio skewed in favour of the fertile female?

Question: Ants have something like a single fertile female to several males. The same applies to bees, and larger animals - elephants too. Is the sex ratio universally skewed in favour of the female? What animal species exhibit this ?
Comment: You mean for animals, right? You get all sorts of crazy sex ratios (and crazy sexes!) going on in plants.
Comment: So just to be clear, you're looking for animals who have sex ratios of male:female <1:>1 in the population, right? Sex ratios within broods, as opposed to within populations can behave strangely.
Comment: @Oreotrephes: Yep. Thanks. Just updated the title
Answer: It is advantageous to have a skew towards more males. Males can be expendable as they are only required briefly for impregnation and can then focus on providing resources for the mother and young and protection. This breaks down when this is no longer the case, for example in humans we are closer to a 50/50 divide.
This article notes that in aphids, there are twice as many females as males, the same is true for daphnia. I don't think the reason behind this is known. In reptiles, the female to male ratio can depend on temperature of incubation thus this can lead to strong fluctuations.
An interesting principle is Fisher's principle:

Fisher's principle explains why for most species, the sex ratio is
  approximately 1:1. Bill Hamilton expounded Fisher's argument in his
  1967 paper on "Extraordinary sex ratios" as follows, given the
  assumption of equal parental expenditure on offspring of both sexes.
  Suppose male births are less common than female. A newborn male then
  has better mating prospects than a newborn female, and therefore can
  expect to have more offspring. Therefore parents genetically disposed
  to produce males tend to have more than average numbers of
  grandchildren born to them. Therefore the genes for male-producing
  tendencies spread, and male births become more common. As the 1:1 sex
  ratio is approached, the advantage associated with producing males
  dies away. The same reasoning holds if females are substituted for
  males throughout. Therefore 1:1 is the equilibrium ratio.
  Source
Comment: At least in some species, aphids have nested parthenogenic vivipary, that is, a female may be pregnant with a female child who is pregnant. Of course, this can result in rapid population growth, and if selected for would explain a higher female ratio.
Answer: In rock hyraxes, similar to elephants, the sex ratio of male to females are between 2:3 and 1:3. Since subadult males are pushed from the population by the territorial male just before they become sexually active. When looking at adult hyraxes, however, the females can outnumber the males by quite some margin.
Recent studies had shown an adult sex ratio of ♂1:♀17 & that the male to female ratio, in populations situated in residential areas, does not show such a big difference.
https://www.ncbi.nlm.nih.gov/pubmed/24899114


When and how should I prune lavender?

Question: I'm currently growing some lavender from seed and I was wondering if I should go ahead a prune it. I know with basil it helps with improving yields and bushiness but I'm not sure if I should prune lavender as aggressively or if it's even necessary (all the lavender on google images I see look like they have a lot of long stems, hence the confusion).
Answer: Lavender is a plant that can get straggly if it's not pruned, but it's a small perennial shrub, so its needs are very different from basil which is an herbaceous annual.
Essentially, you allow lavender to grow until it's reached the size you want for the place you've planted it. Then, every year after that, you cut it back by about ⅓ of its size; it will grow back to the original size during the following growing season. You generally do this after it has finished flowering in autumn to tidy up the dead flowers, but you can also do it in early spring before new growth starts. I use a garden shears to get mine to roughly the shape that I want, and a pair of bypass pruners for trimming any old wood that the shears can't handle easily.
Lavender will recover if cut back to old wood, so you can also use this as an opportunity to shape the plant if desired, cutting it back more in places that are overgrown.
Since you're growing it from seed, you won't need to do it for at least a couple of years. Pinching out the growing tip can encourage the young plant to become bushier, but lavender will generally do that on its own.
Answer: Every plant and tree can use a bit of pruning. The rules pertain mostly to when you can safely prune based on where you are, whether you should prune soft wood versus hard wood, etc.
Old gardening tales aside, nowadays, sites like this and others help us quite a bit. I have definitely made pruning and repotting mistakes and lost some plants along the way, so be prepared for that to happen, at least to a small enough percentage.
All said, the rules for lavender are quite easy, assuming this is the regular kind. Wait till summer is close to ending (check your zone for when this is) and then cut them down. Older lavenders will re-shoot easily than younger ones, so if this is their first year, I'd wait.
Hope that helps.
Answer: There are some pruning rules that must be acknowledged regarding lavender - certainly I agree don't prune until they've flowered the first time, then clip over the bush with a pair of shears or pruners, taking a tiny amount of foliage (less than an inch if they flower this year) at the same time. Subsequently, they should actually be pruned twice a year, immediately after the main flowering in late spring/early summer (varies according to region) and then again very late summer or early fall. Each time you clip back, you should take a small amount of foliage - in the plant's second year, take a good inch of foliage each time. The reason for doing this is because lavender is one of those plants that does not respond to pruning of old wood, and hard pruning back to old wood of a more mature specimen (over 3 years) may well kill the bush. Therefore, to prevent leggy, woody growth over time for as long as possible, it's best to prune twice a year. Even so, the average lavender bush will inevitably become woody and leggy after five years, and are frequently replaced between 5-8 years. It is, though, easy to raise cuttings yourself from the plant for replacement purposes.

When and how should I prune lavender?


wp-login.php bloating log files every 20-30 seconds

Question: Hi has anyone come across this before. It seems like a hack attempt on the site from a bot trying to access it as a wordpress site. This is obviously causing loads of errors in the log files bloating them and making it hard to find any real logs. Is there anything we can do in craft or on the server to block these attempts?
Comment: I like to set up a redirect in that file that sends them to wordpress.org/wp-login
Comment: Note: this is no long term solution but for a quick fix: create the file, so those requests are not routed over Craft. Some people let the visitor download large files so the requests will end sooner or later but I would suggest to just `die()` it out.
Comment: Cheers Robin good tip.
Answer: So what I do is I just redirect anything requesting a WordPress-ish thing to WordPress.com (that's what they are looking for, after all...). You can see how to do that here if you're using Nginx:
https://github.com/nystudio107/nginx-craft/blob/master/sites-available/somedomain.com.conf#L67
Answer: We've done the redirect route in Andrew's answer before and while it keeps some script kiddies out, it can also cause less "savvy" ones to think you actually have a valid WP installation and continue to hit you as well, which doesn't really solve the issue.
nginx is so efficient that we were using a few MBps in our outgoing bandwidth just to redirect a couple offenders before I realized what was hitting our server so hard.
The best option is to:

Detect the attempt / 404 it
Block it at the firewall level after they don't get the hint.

While we use nginx, you can also do some of this on apache. Use:

Rate limiting. Excessive bots will get detected pretty quickly here.
Use fail2ban to subsequently block those repeated attempts.
When you create a location block in nginx, just tell it to log this sort of junk in another file. Then point fail2ban at that log file. This approach works great especially if you have multiple virtual hosts.

Going down the rabbit hole even more, ModSecurity is a super complex beast and not for the faint of heart, but it's common among the big hosting providers to help keep the "riff raff" out.
CloudFlare, StackPath and Inscapsula can also help in this aspect with their web application firewalls if you're willing to let them handle your DNS. These services handle the request before it even gets to your server.
Comment: Yeah for sure, if there is massive traffic, blackhole'ing them is a good idea. For one client, we blackhole'd all of Russia (they had zero customers from there, and tons of bots/spammers)


What is the starting of Samsara?

Question: Every Buddhism believe in Eternity or Samsara. So, how can I imagine of Samsara?. What is the starting of it ?
 Any suggestions would be really appreciated.
Comment: It is unclear what you are asking. What is the "starting life of eternity"? Please clarify what exactly what you're asking about, so as to ensure that your question is not closed.
Comment: no need to be mean. English is a difficult language. This question should be written "Every Buddhist believes in eternity. So, how can I remember my first life?" edit: i have proposed it as an edit to the question.
Comment: @qweilun Is that what OP's question actually is? I'm not trying to be an ass; I just literally did not understand what he meant.
Comment: It's a bit unclear. Do you want to know about your first life, like what you did, where you lived, etc., or about the first starting point of any being in his infinite times of material existence?
Comment: Sorry if I interpreted that way. That's what I think OP means. It's difficult to imagine OP would mean anything else. :)
Answer: Is there a starting point to a circle? Just like that, there's no starting life to Sansara. But you can break this circle at 2 points.

Ignorance.
Craving.

That is when you attain Nibbana.
Comment: if you asked about circle , that may be drawer . if you asked about an egg ,that may be han. So , everythings has their being. where they come from ?
Comment: So what came 1st? Egg or the hen? This is a problem with linear thinking. You can touch any point of the circle and take it as the starting point. But there's always a point before it.
Comment: Yes , Eternity mean absolutely for **Sansara**. Fine . I would like to know what is the starting of **Sansara** ?
Comment: What is the starting of a circle?
Comment: but I don't mean that was due to **Creator** or **God**. I know **Buddha** didn't told about the starting of **Sansara**. Chritians has their starting life .They believe about **Creator**.
Comment: you gave me **Egg or the hen** for instance. pls give me an example for **Sansara**. Can you ? That is the point I would like to get suggestions.
Comment: Circle is the example
Comment: @SankhaKulathantille This is an interesting metaphor, but could you maybe be a bit more explicit? e.g. what exactly does "breaking the circle" mean? Does it mean something like "freeing oneself of ignorance"?
Comment: Yes, once you eliminate ignorance, you no longer crave. Therefore no clinging. Which means no rebirth. Read about Paticca Samuppada.
https://www.youtube.com/watch?v=n_llBSCXt6c
Comment: @Cataclysm Well, I don't mean to beat my own drum, but the question of origin had troubled me a lot. After years of practice and search I realized the answer to be Nothing. That is my theory. Everything indeed runs in a cycle. If you are really looking for an answer then you might want to check my solution of this problem at http://shunyavada.com/
Answer: According to the suttas, samsara has no beginning. There are many references to this.
Comment: The suttas you referenced don't say "no beginning": they say "inconstruable" and "not evident". Whether "the world is infinite" is one of the "unanswered questions".
Answer: The answer to your question depends on how one understands the word "start." Etymologically, the English word means to jump, leap up, or move or spring suddenly, thus, to arise, to come into being. In accordance with the law of karma, the whole process of samsara itself must be self-starting.
This can be proved logically based on the law of karma, which requires that every cause have an effect and every effect a cause. Since samsara is time itself, the essence of time is the identity of cause and effect, thus, the moment, which is then extended in space as past and future to create the infinitely differentiated  world that we experience.
However, as the illusory negation of reality samsara must inhere in the non-illusory, which is reality itself. Therefore, samsara also inheres in reality, and in that sense has a logical - but not a temporal - "origin." This "start" is the principle of karma itself, which is the inherent kinetic principle in transdual reality.
This is necessary to explain our experience of samsara. Otherwise, there would just be nothing at all. This point of identity of samsara and reality is, once again, the moment. Therefore, the answer to your question is that the start of samsara is the inherently timeless and therefore eternal moment, which paradoxically is the origin of time, space, and causality that endlessly differentiates in infinitely variegated patterns. This view of the cosmos remarkably presages certain theories in modern physics, especially the holographic theory of the universe.
Answer: Beginning of Samsara is stated by Buddha as not knowable for ordinary beings. Knowing rightly would be to not imagine in regard of its beginning.
Usually Samsara is imagined as round of re-births in the six realms, or much more detailed view as bhavacakra.
Answer: Your question has two parts so i will answer in the following order...
How to understand "Samsara" and how it works.
Sansara or Samsara is the word Lord Buddha picked to name a certain circle of death and life.
What is samsara
As we Buddhists believe as long as a being lust for existence he will be born according to his Karma.To this process we call "Sansara or Samsara".
So where is the start of samsara?
Even Lord Buddha was intrigued by the question and started to find a solution.The only way to do it is to look back into your own past to find your first life.So Lord Buddha went back countless amount of lives and understood that the "Beginning" is very ancient the time we have in a life is not enough to look back and see that life.So lord Buddha said this to the Sangha  "There is no point in looking for a start,it is too old and trying to find an answer is a waste of time".And advised that no one should try to find an answer to it (Because they will not be able to find it)
So my friend that question can't be answered by any being in the universe,Because if there is something out of Lord Buddha's reach it is out of anyone's reach.
So how does samsara work?
How it works is complicated but i will give you a simplified version of it.
Samsara needs fuel like your car,As long as you give fuel to it it will keep working and you will have life after life to live.
Let me give an example from lord Buddha....
"Karma is the paddy field,Lusting is the water,vinyana is the seed"
In the real world without water a seed will not grow,likewise without "Greed or lust" you will not be born,without it there is no samsara but as long as you have it you will have samsara and you will have to suffer in whatever karma brings you.
Answer: The beginning of samsara is inconstruable and not evident, yes, but it definitely happened when the mind-body phenomena emerged out of ignorance and started craving and clinging.

As he was sitting there he said to the Blessed One: "'A being,' lord.
'A being,' it's said. To what extent is one said to be 'a being'?"
"Any desire, passion, delight, or craving for form, Radha: when one is
caught up there, tied up there, one is said to be 'a being.'
"Any desire, passion, delight, or craving for feeling... perception...
fabrications...
"Any desire, passion, delight, or craving for consciousness, Radha:
when one is caught up there, tied up there, one is said to be 'a
being.'
SN 23.2
Answer: From objective perspective, Samsara is a beginningless round of deaths and rebirths the beings are stuck in. "Beginningless" means it has no beginning. The question you may ask: if Samsara has no beginning, and I am in it, how did I come to exist? This seems like a real puzzle.
Another piece of the puzzle is Buddha's suggestion that despite being beginningless, Samsara has an end. The end of Samsara is attainment of Nirvana.
The usual superficial understanding of these is to assume that one can escape Samsara, stop the round of deaths-and-rebirth, and effectively spend the rest of eternity in a state of perpetual lack of suffering.
Such answer though would omit a very important construct of Buddhism, one of "Three Marks of Existence"
According to Buddha, existence inevitably has the characteristics of

Impermanence
Suffering
Selflessness (nonsubstantiality)

Which means, a state of perpetual lack of suffering would contradict the fundamental law of the universe (as presented in the Three Marks). How could it be perpetual given the impermanence? How can suffering cease, given that suffering is an intrinsic characteristic of existence? How can I spend the rest of eternity in this state if "I" (self) does not exist?
This seems like a serious contradiction. And yet Buddha insists, there is a way to solve this conundrum, there is a way to attain Nirvana.
Without giving too much away, I would like to hint at the direction the answer lies in:
Samsara begins when subject and object separate from each other. Samsara ends when subject and object are no longer separated. The answer lies in the realm of phenomenological experience, including experience of suffering, life, and death. Good luck with your quest!
Comment: Not necessarily, but one sentence answers provide very little in the way of benefit to the person asking the question; opinions and personal experience based answers are similarly unlikely to help much. Definitely this answer is too brief to be of much use, and so it was flagged as "low-quality".
Comment: Could you elaborate on this? The exact meaning of your answer is probably obvious to experienced Buddhist practitioners, but it is unclear to me what "subject" and "object" are in this context.
Comment: It would at least be good if you could provide a source to back up your answer, though it does sound intriguing :)
Comment: this is an important methodological question @Yuttadhammo -- are we saying it is a requirement to back all our answers with sources, or is it enough to go by experience and "general understanding"
Comment: Please see meta discussion here: http://meta.buddhism.stackexchange.com/questions/26/should-we-allow-encourage-short-enigmatic-answers/
Answer: Buddhism basically deals with the present. Dwelling the mind on past or future unnecessarily creates mental vexation. Hence, concepts like God, origin, etc. are not dealt in Buddhism. It doesn't matter why or how the samsara came into existence, what matters is that samsara does exist. Now when samsara exists and we exist, our effort should be eradicating problems that give rise to suffering. For example, because you are thinking about the origin, you are to some amount troubled by the question. So as per Buddhism you should not focus your mind on such irrelevant questions as they unnecessarily create suffering.
However, if you are really looking for answers then you should consider studying the philosophy of other religions. If you do, then you will find the answer to be God. Then the question of starting point of God will arise in your mind. If you look into science, it says Big Bang is the starting point. But in my view, Nothing is the starting point. Only that which has come to exist can have a starting point. How can that which doesn't even exist have a starting point? I know this sounds ambiguous, but it's hard to explain here in few words. You can check the following link if you like, but my findings there is based on Vedic scriptures: http://shunyavada.com/

What is the starting of Samsara?


Can a Bitcoin (secp256k1) key be converted to a Ed25519 (Tor v3) key?

Question: If I have secp256k1 keypair that is widely known, like a Bitcoin address, can I convert that into a Ed25519 key pair such that someone could access a .onion address in a deterministic way?
Answer: The bitcoin key could sign a message containing the onion address. There are several other alternatives but there isn't any way to do this without the key holder producing a message of some kind.
Comment: Even if you had the full public key, you can't convert it to a ed25519 public key in such a way that the private key can be converted in a compatible manner. The secp256k1 and ed25519 have different structure.
Comment: Thanks. It makes sense now that I think about it because there is no way to get the ECC coordinates from the hashed address alone.
Answer: No you can't convert them since they are defined over different curves.


Constant color on all platforms

Question: I design profile picture and cover photo for Twitter and I want to pick a color that I will want to use also on other platforms, such as Facebook and any other web page, but I want to be sure it will look the same on computer screen, smartphone and maximum close on printing materials. For example, I pick a color from pantone gallery and there is rgb and cmyk codes, is that safe to use these? And can I start a new illustrator document with rgb mode, fill object with the color from rgb code and then paste in cmyk document the same object and fix cmyk numbers, is that ok?
Comment: Short answer—no. Longer answer is well, a lot longer.
Comment: Can you please explain in a bit longer answer?
Comment: I'm a bit busy at work at the minute but I will once I have time, if you don't get an answer by then. (I'm sure you can probably find an answer if you [search previous Q&As](http://graphicdesign.stackexchange.com/search?q=consistent+color) though)
Answer: I don't actually see a question quite this broad though as Cai mentioned in comment there are a number of questions the cover various reasons on this in more specific use cases, color-reproduction
What it boils down to though is that color is based on human perception. People don't see colors the same, monitors don't see colors the same either. What color wall your in front of, the color and power of any lights around you including the sun, if your eyes are fatigued, if you even have perfect color vision to begin with (color blindness) --- all of these influence what color you perceive.
So even if you select a color within the most common parts of the RGB/CMYK color space and you'd still get variances. Combine that with 99.9% of people never calibrating their monitors and a clear 100% never calibrating mobile devices and any concept of accurate color consistency goes away.
Pantone will help get consistent colors on products. For example the Coke Red uses pantone so their shirts, vehicles, vending machines, signage, all of it gets the exact same red because pantone is carefully calibrated and essentially premixed to Coke's specifications. Even Coke though online or in advertising ends up with some level of variance. A Coke ad in a newspaper for example will be forced to use CMYK and might look darker and less vibrant than their Pantone would've.

Constant color on all platforms


Bitcoin Mining using an iPhone?

Question: Is it possible to start Bitcoin mining using an iPhone with 4G internet connection?
Storage is not an issue,or is it?
(Mine is 256GB).
Comment: In principle you could, but in reality the processing power is way too small. So you wouldn't have a chance to find a block before others do. Mining is done today on specialized hardware.
Answer:
Is it possible to start Bitcoin mining using an iPhone with 4G internet connection?

Yes. It is theoretically possible to start mining with an iPhone.
Your internet connection is almost completely irrelevant and your space is also not important. The important thing is the power of your CPU.
But: Mining with an iPhone means mining with CPU. And that's completely unprofitable. Even mining with GPU is not profitable anymore because of all the ASICs. You would fight against big mining pools and you would probably never be the first one who gets a hash with 20 zeros. So, you would waste a lot of energy and don't get any reward. Not worth it!
Answer: Theoretically it is possible, but in reality, cryptos are mined either by multiple fast GPUs (e.g. 1.5 USD daily income per GTX1080Ti minus the electricity costs) or by special equipment made only for the purpose of mining (ASICs). These devices are much, much faster and better suited for mining than an iPhones CPU. So in reality, you would need multiple years of work done by your iPhones CPU just to receive a tiny, tiny fraction of a bitcoin.
There is however one special cryptocurrency which is suited for mining by mobile CPUs: Electroneum. You can download the app and start mining with little effort and get some fractions of a cent per day at the current low prices. However, you should know, that even that is only a fake mining as the Electroneum coins you receive have already been premined and you only get a reward for wasting electricity with your mobile phone. Its simply a marketing move to "simulate" how it is to mine cryptocurrency and you can read it in Electroneums whitepaper.
TLDR: Forget mining of cryptocurrencis with CPUs in general, doesnt matter if mobile or desktop.

Bitcoin Mining using an iPhone?


How do I use Views Global Filter with Geofield 2.x Exposed Proximity Filter?

Question: I am trying to set it up so that a views global filter  https://drupal.org/project/global_filter can set the distance and city for the proximity filter for Geofield? What are the steps to do this?
Answer: Add a filter that precedes that filter that is not exposed and creates the initial filter you want. Usually you can do this with most views handler filters, so it should work with the proximity filter.


Prickly pear wilting after being in the sun

Question: my prickly pear has been doing great, until this morning I put it outside in direct sun and within a few hours the new baby on the top started to lean. I also watered it the same day. Any ideas as to why?
I normally keep it inside in direct sunlight on my window sill. The temp in my apartment is normally around 70 degrees.
Answer: Direct sunlight outdoors is not the same as sunlight through a window - UVA gets through glass, but UVB rays do not, so your plant was not ready to cope with suddenly being exposed to full on sunlight. If you want to move a plant outdoors into sun, it has to be done gradually, with limited exposure initially and preferably not in the middle of the day to start with.
Decide whether you want the plant outdoors or inside - if you want it outdoors, just keep it in dappled sunlight or put it in early morning sun, then into shade, increasing its exposure to sunlight over a week or two, until its in full sun all the time.
Comment: Every plant I've ever dealt with, including cacti, needs hardening off in partial shade before you can put them in full sun. Otherwise you get wilting, scalding, even death.


Does a composite primary key break the first normal form?

Question: Does having a composite/compound key (using multiple columns/attributes) to form the primary key break first normal form? (I am assuming that this is handled by the DBMS, and so the attribute containing composite key does not exist in the table/relation itself, and so this still complies with the first normal form, but is this correct?) thanks.
Answer: No, this is quite normal (pun intended). The criteria is

First Normal Form:
Tables are said to be in first normal form when:

The table has a primary key.
No single attribute (column) has multiple values.
The non-key attributes (columns) depend on the primary key.

None of these requirements for 1NF is violated by the design you propose.
For instance a Junction Table created to normalize a many-to-many relationship will always have a composite Primary Key, with each component being also a Foreign Key into one of the joined tables.
Comment: You said "The non-key attributes (columns) depend on the primary key". Does it mean that if a non-key attribute transitively depends on the primary key, then the table is in First Normal Form?
Comment: I don't know, from where you got this definition. But, 1NF talks that every attributes must have atomic value. There is no concept of Primary Key in its definition. Also, during design phase i.e. Relational design phase we don't use the term Primary Key in its definition. We use Candidate key. Can you please provide the proper link of the definition you have stated? Inscribed link doesn't work.
Answer: A table in First Normal Form can have a composite key that have many columns to form a primary key:
When a table in the first normal form:

has a primary key.
No attribute/column has multiple values.
The non-key attributes/columns depend on the primary key.
The non-key has no repeating groups in attributes/Columns

For instance, the following two examples are not in the first normal form:
One student table with a student ID and class:
1st example: class column has many values.
2nd example: classes are repeating groups.

<code>a.  Student_id, (class_1, class_2,class_3).
b.  Student_id, class_1, class_2, class_3
</code>