Does the sea level increase if an iceberg melts?

Question: It was claimed that if an iceberg melts in the ocean, the sea level won't change as the ice displaces as much water as there will be melted water. The other claim was that the sea level should rise because oceans contain salt, so the water in oceans is denser than the water in the ice. Which one is the correct reasoning?
Comment: Just in case--Because this is a Physics board the answers here are properly scoped and totally correct--floating ice won't effect sea level, but what actually happens is more serious.  If you want real world evaluations you should google how a disintegrating ice shelf allows land-based ice behind it to flow into the sea (Which does raise sea levels).  Also google "Atlantic conveyer belt" which, although not directly tied to sea level rise, shows how melting ice can have surprising consequences.
Comment: I think this is very easy to test yourself.  Fill a pitcher with 1L salt watter, insert ice (from normal watter without salt), check the water level, wait till its melts and check the water level again.
Answer: The Archimedes principle says that a floating body will displace an amount of fluid that is equal to its weight.
Since the iceberg floats, it weighs the same as the water it displaces. If it had the same salt concentration as the ocean, then once thawed, it would occupy exactly the same volume as it displaced and the sea level wouldn't change.
But most icebergs are made of nonsalty water, with a density a bit lower than sea water. So once melted, that same mass will occupy more volume (same mass, less density equals more volume), and the sea level will increase… very very slightly.
Comment: If the iceberg floats, it must weigh *less than* the water it displaces. Also, ice has a lower density than water. (It expands as it freezes.)
Comment: Comments are not for extended discussion; this conversation has been [moved to chat](http://chat.stackexchange.com/rooms/62237/discussion-on-answer-by-rodrigo-does-the-sea-level-increase-if-an-iceberg-melts).
Comment: @DavidLively There are two forces acting on the iceberg: gravity and buoyancy. If the iceberg is not moving (equilibrium) then they are exact opposites. I you pushed the iceberg down so that it is fully submerged then it would displace more water and the buoyancy will be greater than weight and it will push up, back to the equilibrium position.
Comment: There is another aspect.  If an iceberg melts, some water at 0°C will flow into the ocean, just making the ocean ever so slightly cooler.  Or, put differently: the ice will extract heat from the surrounding liquid in order to melt.  This effect is tiny, as is the effect you describe.  Between those tiny effects, who wins?
Comment: @rodrigo yes, but that doesn't address my point. The equilibrium point is a function of the relative density. If the water and ice had the same density - same *weight* in your statement - and disregarding increasing pressure as depth increases, we wouldn't see 15% of the iceberg above the surface.
Comment: @DavidLively You are mixing concepts. Equilibrium happens when the sum of forces (weight plus buoyancy) equals zero. When the object is fully submerged that is equivalent to compare densities, because the volume of water displaced equals the volume of the object itself. If the object is partially submerged the weight is the same but buoyancy is not, because the are less volume displaced, and then equilibrium is a matter of densities and position.
Comment: @gerrit: Ah, that is a tricky one. Thermal expantion coefficient of water is negative at 0ºC, is 0 at 4ºC, and positive above that. My answer just assumes a constant temperature of 0ºC both in the ice and in the water around it.
Comment: @gerrit: Moreover the thermal expansion of water at 0ºC is tiny compared to the change of volume when freezing.
Answer: The one you're not contemplating: that the sea level rises because of melting of ice that's currently over land. As noted in Rodrigo's answer, when sea ice melts there is no change in the water level, and if the ice is made from fresh water then there will be a small change due to the mismatch in densities. However, that ignores the fact that there is a huge quantity of ice in ice caps and glaciers over land, and if that ice melts then it will contribute to a rise in sea levels.
Comment: The question as posed used deeply flawed assumptions which are important to set straight on a permanent record in this thread. If folks have better ideas for answers, they're welcome to add their own, and if they're happy to downvote correct and important content, that's their choice.
Comment: Your last statement, while true, does not address the question as asked. I think it is generally accepted that an iceberg is floating ice ("a large floating mass of ice detached from a glacier or ice sheet and carried out to sea.") . And it is the melting of icebergs (not "Arctic Ice") that is the subject of the question. Which makes this more of a comment than an answer...
Comment: As stated in another comment, potential sea level rise from melting sea ice is very small (and, modulo the fresh water thing, is actually zero)  compared to that from land ice (which really means Greenland and Antarctica).  The naïve physicist (me) will then do sums to compute the time constants for such melting and will decide that it is not something to worry about just yet.  The less naïve land-ice person will then point out that *land ice can become sea ice* and this might happen quite quickly but we just don't know.  So the big risk is not melting, it's sliding off the land.
Comment: I'm pretty sure this is by far the bigger reason.  The density fluctuations of icebergs would be absolutely minuscule when you consider the amount of icebergs compared to the density difference between that and water, compared to the total amount of water (quite small).  Glaciers and melting snows on the other hand come from the land; so their entire volume has an effect on the water level.
Answer: It is true that when pure ice melts in pure water, the water level does not rise. However, the oceans are salty and this makes a big difference. When pure water melts into the salty ocean, water level rises. Your latter reasoning is the correct reasoning.
This answer discusses the physics and the mathematical details behind what we observe and then applies the same to the reality.

Mathematical Details:
Let the density of ice and water be $\rho_{\text{ice}}$ and $\rho_{\text{water}}$ respectively.

The density of ice is lesser than that of water and hence ice floats on water. Part of the ice will be submerged and the rest will stay above the surface.
The submerged part of the ice is responsible for the buoyant force provided by water.
Let the total volume of ice be $V_{\text{tot}}$ and the volume of the ice submerged under water be $V_{\text{sub}}$.
According to Archimedes principle, the buoyant force provided by water is given by:
$$F_{\text{buoy}} = V_{\text{sub}} \rho_{\text{water}} g$$
The weight of the ice is given by:
$$F_{\text{weight}} = m_{\text{ice}}g = \rho_{\text{ice}} V_{\text{tot}} g $$
As the ice floats on water, the buoyant force must balance the weight of the ice.
$$F_{\text{buoy}} = F_{\text{weight}}$$
$$V_{\text{sub}} \rho_{\text{water}} g = \rho_{\text{ice}} V_{\text{tot}} g$$
$$V_{\text{sub}} = V_{\text{tot}}\frac{\rho_{\text{ice}}}{\rho_{\text{water}}} \tag{1}$$
After the ice melts, the mass of ice would've turned into liquid water. The density has changed but the mass hasn't.
Let $V_{\text{new}}$ be the volume occupied by the ice mass in its water form.
$$m_{\text{ice}} = V_{\text{tot}} \rho_{\text{ice}} = V_{\text{new}} \rho_{\text{water}}$$
$$V_{\text{new}} = V_{\text{tot}}\frac{\rho_{\text{ice}}}{\rho_{\text{water}}} \tag{2}$$
Inferences:
Compare equation $(1)$ with equation $(2)$. You'll notice that $V_{\text{new}}$ is exactly equal to $V_{\text{sub}}$.
This result can be interpreted as: the volume occupied by the submerged portion is equal to the total volume occupied by the ice in its water form.
To put in a nutshell, the volume under the sea surface hasn't changed due to the melting of ice.
Therefore, melting of ice does not affect the sea level.
What if the ice and water both had dissolved salts?
This in no way alters the equations $(1)$ and $(2)$. Therefore, the previous inference remains valid.
What if the ice is made up of pure water and the sea is salty?
The equations $(1)$ and $(2)$ would change to the equations given below:
$$V_{\text{sub}} = V_{\text{tot-pure-ice}}\frac{\rho_{\text{ice}}}{\rho_{\text{water-salty}}} \tag{3}$$
$$V_{\text{new}} = V_{\text{tot-pure-ice}}\frac{\rho_{\text{ice}}}{\rho_{\text{water-pure}}} \tag{4}$$
As salt water is more dense than pure water, $\rho_{\text{water-pure}}$ is smaller than $\rho_{\text{water-salty}}$.
Using the previous statement and analyzing the equations, it can be inferred that sea level rises when a pure block of ice melts in a salty sea.
What if the ice is made up of salt water and the sea is pure water?
$$V_{\text{sub}} = V_{\text{tot-salty-ice}}\frac{\rho_{\text{ice-salty}}}{\rho_{\text{water-pure}}} \tag{5}$$
$$V_{\text{new}} = V_{\text{tot-salty-ice}}\frac{\rho_{\text{ice-salty}}}{\rho_{\text{water-salty}}} \tag{6}$$
As salt water is more dense than pure water, $\rho_{\text{water-pure}}$ is smaller than $\rho_{\text{water-salty}}$.
Using the previous statement and analyzing the equations, it can be inferred that sea level goes down when a salty block of ice melts in a sea made up of pure water.
Conclusions:

If an ice made up of pure water melts in an ocean of pure water, the sea level does not change.
If an ice made up of pure water melts in an ocean of salty water, the sea level rises.
If an ice made up of salty water melts in an ocean of pure water, the sea level goes down.
If an ice made up of salty water melts in an ocean of salty water, the sea level does not change.

Melting of ice & its relationship with sea level
Out of the 4 cases mentioned in the conclusion of the mathematical details section, only the following are likely scenarios on earth:

Pure ice melts into the salty ocean
Salty ice melts into the salty ocean

The remaining two cases are quite unlikely because we don't really have pure water (a.k.a fresh water) oceans and seas.
The glacial ice and ice shelves (these are on land) are made up of snow which is frozen pure water. Due to warming climate (climate change!), large chunks of these fresh water reserves break off and floats into the sea. These are called icebergs (these are floating in the sea). Therefore, when these kind of icebergs melt, they cause the sea level to rise.
When salt water begins to freeze, the ice formed contains the dissolved salts. When this salty ice melts into the salty ocean, the sea level does not change.
If you put those two cases together, we can conclude that the sea level can either rise or remain same due to the melting of ice.

Significance of melting ice

Sea-level rise is governed by processes that alter the volume of water
  in the global ocean—primarily thermal expansion of sea water and
  transfers of water from terrestrial reservoirs, such as land ice and
  groundwater, to the ocean. The Intergovernmental Panel on Climate
  Change (IPCC) Fourth Assessment Report found that thermal expansion
  accounted for about one-quarter of the observed sea-level rise for
  1961–2003, melting of land ice accounted for less than half, and
  changes in land water storage accounted for less than 10 percent
  (Bindoff et al., 2007). For the last 10 years of that period
  (1993–2003), the IPCC estimated that thermal expansion and land ice
  melt each contributed about half to the total sea-level rise. The
  improved agreement between estimates of the individual contributions
  and the total sea-level rise for the later time period was attributed
  to the availability of satellite altimetry data and other global ocean
  data sets and to better knowledge of the processes causing sea-level
  rise. Subsequent work has corrected instrument biases, reducing
  estimates of the thermal expansion contribution to sea-level rise, and
  recorded increased rates of land ice loss. In the most recent
  estimate, for 1993–2008, the contribution from land ice increased to
  68 percent, the contribution from thermal expansion decreased to 35
  percent, and land water storage contributed -3 percent (sea-level
  fall; Church et al., 2011).
Source: https://www.nap.edu/read/13389/chapter/5

Melting of ice is the largest contributor towards sea level rise.
Additional references for the previous statement:

Causes of Sea Level Rise: What the Science Tells Us (2013) - www.ucsusa.org
Is sea level rising? - oceanservice.noaa.gov
Sea level rise - Contributions - Wikipedia
Answer: Yes, if an iceberg melts, it will increase the sea level but that increase in sea level is totally negligible. According to this recent article that shows the breaking of Larsen C ice shelf (is considered the largest iceberg crack till date) :

Yes, Sea Levels Will Rise Thanks to the New Iceberg in the Southern  Ocean
Scientists estimate that as the 'iceberg melts, it'll add about 0.1
  millimeters to the total sea level rise. When compared to the rise
  that NASA and NOAA are already measuring — currently 3.4 millimeters
  per year — this 0.1 millimeters might seem relatively
  inconsequential.
If the Larsen C ice shelf, however, was not a shelf — meaning it was
  on land and not already plopped down in Earth's ocean — climate
  scientists like NASA's Gavin Schmidt estimate the trillion-plus metric
  tons of ice would have added significantly more water to Earth's seas,
  resulting in some 2.8 millimeters of rise. This amounts to over 80
  percent of the sea level rise already happening each year.

There is also a graph which shows the level of sea rise with time (also from same article):

This likely means that we're in for some three feet of sea level rise, at minimum, explains Steve Nerem, the lead of NASA's Sea Level
  Change Team:

"Given what we know now about how the ocean expands as it warms and
    how ice sheets and glaciers are adding water to the seas, it's pretty
    certain we are locked into at least 3 feet [0.9 meter] of sea level
    rise. But we don't know whether it will happen in 100 years or 200
    years."
Comment: You do realise the water came from the ocean in the first place.
Answer: There are already great answers to this question. This answer is just a slightly intuitive version of Yashas' answer based on this answer to a related question, Why does ice melting not change the water level in a container?
We shall analyse what happens to the water level after the ice melts completely for four different cases, which arise due to the difference in the nature of ice and water:

Case 1: Ice made of pure water floating on pure water
Case 2: Ice made of pure water floating on salt water
Case 3: Ice made of salt water floating on pure water
Case 4: Ice made of salt water floating on salt water

In the analysis of all the four cases, I've added an intermediate step labelled (c) using an 'imaginary container'. This container is introduced to bring out the reason for the difference in the levels of water in cases 2 and 3. This doesn't make any difference in cases 1 and 4.
In step (b), the imaginary container is added without disturbing the system. Then the ice is allowed to melt within the container. After melting, the level of water inside the imaginary container may or may not be the same as that of the outside. Then, in step (d), the imaginary container is removed. Or, for the sake of simplicity, imagine that the imaginary container alone vanishes by some means. The water which was initially inside the imaginary container now mixes with the water outside and the water level of the beaker attains equilibrium. The horizontal green line represents the initial water level in the beaker. Figure 1 is annotated for the reader's convenience.
First, let's consider case 1, where a piece of ice made of pure water floats on pure water in a beaker. As per the Archimedes' principle, the buoyant force on the ice is equal to the weight of liquid displaced by it. Here, the volume of liquid (water) displaced by the ice is equal to the volume of submerged ice (labelled part 2). Weight of the ice, parts 1 and 2 combined, is equal to the weight of water of volume equal to part 2. When the ice of volume parts 1 and 2 melts, the water obtained occupies only volume equal to that of part 2. This is because of the fact ice is less dense than water. The net result is the water level in the beaker remains the same.

As mentioned in the beginning of the answer, this explanation is based on this answer. Now, let's extend this to other cases. Next on our list is case 2, where a piece of ice made of pure water floats on salt water. We know that salt water is denser than pure water. So the same mass of ice displaces less amount of salt water. Or in other words the submerged volume is less than that of the previous case. The weight of salt water of volume part 2 is equal to the weight of the ice, as per the Archimedes' principle. But, as we allow the ice to melt inside the imaginary container, the water obtained occupies more volume than part 2. This is because pure water is less dense than salt water. This is where the imaginary container helps us to see the difference.

In (c), we can see that the level of water inside the imaginary container is higher than that of the outside. So, when we remove the imaginary container in step (d), the water level in the beaker rises.
Now, let's move on to case 3, where a piece of ice made of salt water floats on pure water. As the ice made of salt water is denser than the ice made of pure water, it displaces more water compared to the pure ice. Again, as per the Archimedes' principle, weight of ice is equal to weight of pure water of volume part 2. But, this time as the ice melts, the salt water obtained occupies a lesser volume than that of part 2.

In (c) we can see that the level of water inside the imaginary container is less than that of the outside. When we remove the imagniary container in step (d), the water level in the beaker drops. The final case in our analysis is a piece of ice made of salt water floating on salt water. This case is very similar to case 1 and the level remains unchanged.

So far we dealt with pieces of ice floating on water in a beaker. Scaling things up, the results obtained here apply to icebergs floating on oceans. As Yashas described, we know from our experience that sea water is salty, and hence only cases 2 and 4 are possible. So, as icebergs melt sea level must either increase or remain the same.
However, the major contributor to the rise in sea level is not due to melting of ice floating on water, but is due to melting of ice on land which is not floating. This is like pouring water in a cup of water. This fact is well explained in Nilay Ghosh's answer.
Answer: Apart from the salty/freshwater discussion.
If all floating ice (the future for the Northern ice cap looks dim) is melted, less radiation from the Sun is reflected back in the atmosphere. More radiation is absorbed by the water that takes the place of the ice. This on its turn means that the oceans are slightly warmed. Because the average temperature of the surface water on Earth is about 17 degrees Celcius (look here) the water will slightly expand and cause a slightly higher sea level.
More importantly, because the temperature of the water is slightly raised some organisms in the seas and oceans (especially where the water is not too deep), which are very sensitive to the temperature of the water will not have enough time to adapt (evolution is a slow process) and suffer the consequences.
And also, more importantly, is the ice that covers the landmasses. Glaciers are melting and moving at disturbing rates. Water coming from this ice will significantly make the sea level rise.


Why the nature of things is such as it is?

Question: Namaste. My question is
Why the nature of things is such as it is?
I think that the question cannot be answered, because it points outside the grasp of our mind, but I am interested in possible deep evidences pro or contra.
Thanks.
Answer: When you say the nature of things i am assuming you mean things being:
1.Impermanent (anicca)
2.Suffering/Dissatisfaction/Dis-Ease (dukkha)
3.Non Self (annatta)
1.Why is the nature of things impermanent?
Because conditioned phenomenon is constantly in a state of flux.Why?Because something causes this to happen than this causes that to happen then that causes that to happen then...and so forth.
2.Why is the nature of things suffering/dissatisfaction/Dis-Ease?
Because the conditioned phenomenon keeps changing.(impermanence).And we keep grasping at it.What happens when you try to hold on to something that keeps moving and your adamant about staying put.You hurt yourself.You stress yourself.Let go.
3.Why is the nature of thing Annatta?
I can not answer this.It just IS.
Both Samsara and Nibbanna are devoid of an Ego.Both conditioned and the unconditioned have no permanent self/Ego.
Answer: This is a broad question, perhaps a whole category of questions.

Is the world like it is because it was created that way (by a creator God) for some reason?
No, Buddhism doesn't accept/teach about a 'creator deity'.

What do we know about the creation of the world?
Not much: it has "no discernible beginning".

What ought we to care about the creation of the world?
The Buddha said that instead of talking about such things, his intention was to teach about suffering and the end of suffering.

What is the nature of things?
The nature of things includes the 'three marks of existence', the laws of 'karma' and 'dependent origination', etc. etc.

Perhaps some interesting questions include:

Why do we perceive the nature of things to be as we perceive it?
Answers to that question include the theory of 'skandhas' and of 'identity view'.

Can we change the nature of things?
Well, good actions and evil actions, skillful and unskillful actions, have an effect.

Can we change our perception of the nature of things?
Supposedly yes: doings so is pretty well the purpose of Buddhism.
Answer: Short Answer: Because that's the way it is, and it doesn't matter.  Please read The Parable of the Poisoned Arrow.
Long Answer:
There is no satisfying answer to this question because we're only asking because things happen to be this way.  If they were another way, we'd ask why things were THAT way.
It may be better to ask instead why you are asking that question.  Why not just accept that this is reality and that's that?  The very question you ask implies an attempt to give human existence cosmological importance. If so, what does this say about the attachment to your belief in your importance?  In short, is the question itself a symptom of an anthrocentric bias or agenda?
Now let's bring this back to Buddhism.
If you want to know why things are the way they are, then there is a Buddhist parable which is THE BEST Buddhist teaching I've seen on this and other metaphysical questions. It's called The Parable of the Poisoned Arrow.  If you haven't read it, I recommend you do.  It teaches that only thing that matters is relieving your suffering, so stop the pointless speculation.
If you spend your time worrying about these things, then not only will you be distracted from the only thing that matters (relieving your suffering), but you may increase your suffering by agonizing about something you can't change.  Yes, nothing is more conducive to suffering than worrying about what's out of your control.
Which brings us to suffering. Buddhism has its 3 Marks of Existence. I'd interpret that as the 3 Marks of Experience. After all, suffering does not exist in the universe -- rocks, planets, and hydrogen atoms don't suffer, or at least I don't think they do.  Suffering is our REACTION to things, a reaction we can change, and this is where Buddhism is (and should always be)  situated.
Trying to elevate suffering into some kind of cosmological principle misses the point, and makes relieving suffering harder, by dramatizing it. Realizing the true role of suffering can put it into perspective and this itself is a big step towards relieving it.
Comment: The parable of the poisoned arrow always seemed like a cop-out to me. The historical Buddha seems happy to speak of many other esoteric, metaphysical things not directly related to the goal eliminating/escaping suffering, so his silence on the "unanswerable questions" on that basis seems suspect to my deluded, ego-attached mind.
Comment: @BrentCaldwell which is as it should be.
Answer: We don't see the nature of things since:

our mind is not focused enough
our mind is clouded by perception

So my developing insight leading to the cessation of perception and developing concentration you can see things as they are.
Answer: Before we come here, it is not easy  to see that a)
to get to b) means... I will suffer this and that. Before we come, all we
know is we wish to get from a) to b). For beings who are willing to see
 past the illusion, it works.
Answer: To give you personally fulfilment and happiness in everything you do. Could there be any other meaning for you? Some questions are merry-go-rounds, all take part and everyone goes round and round for fun. This one isn't like that. Or if it is, it is a roundabout for one.


Should I apply to an academic tenure-track job even if I am not a 100% fit?

Question: I am geographically limited in my academic job search. I have seen some jobs I am qualified for, but might not be 100% fit. For example, I have the qualifications but only a few papers on the topic whereas most of my work is in other areas. Any insight would be appreciated!
Comment: You are looking for a job that suits you, not for a job that you are a good fit for.
Comment: This is a deeply personal questions that is unanswerable here. The answer entirely depends on your own personal preferences.
Comment: yes, yes, yes. Oh, to be sure: yes
Comment: Unicorns can exist in both employers and employees.
Comment: One aspect that I don't think many are considering here is you will have to ask your referees for a reference. They may not appreciate having to write a large number of references for jobs that don't seem like a good match.
Answer: Not applying is suboptimal and self defeating. It is the university that you apply to that makes the determination of your "fit". They know things that you don't and there may be factors that make you seem better to them than you do to yourself.
Yes. Apply. Put some effort into it.
Comment: BEST Answer ! !
Answer: Being a perfect perfect fit is unreal.
Many applicants may have abilities/experiences that you lack, and you may have many other abilities/experiences that they lack.
Applying is the only way to be considered to get the job. Skills that you need to get the job done may come with some time in the job.
Apply, and if you don't get the job, apply for the next offer you find.
Comment: In the 1980s, when he was just out of grad school (having finished both a PhD in cultural anthropology and a JD), my father applied for a teaching position.  They were looking for someone with research experience on the Navajo Nation (which was my father's research area) who also had experience in the law (my father clerked for Justice Feldman, and then served as legal advisor to the minority party in the state House for several years).  There were a bunch of other weird little details in the job description which exactly fit my father's experience.
Comment: It turns out that the job description had actually been written in an extremely narrow way so that they could hire a specific person (not my father).  Boy were they pissed when they had to interview him, anyway (even if they didn't end up offering him the spot).
Comment: But this is the exception that proves the rule.  In general, no one is ever a perfect fit for any position. :D
Comment: @XanderHenderson - You should really try to turn those comments into an answer... it is a good anecdote
Answer: If it's somewhere that you could envision yourself being successful and somewhere that you would like to work then you should apply.
Often the research areas specified in an advertisement are the result of an internal negotiation with different people having a different opinion about what is needed (or would benefit them the most). So they are not necessarily rigid requirements. Depending on how specific the requirements are there may be few, if any, people who are a 100% fit.
The panel can ask for anything they want but ultimately they will need to choose from the applications they receive. Just make a solid case for why your experience/future plans complement the department/university (and are viable there) in the application.
Answer: "Don't put limitations on yourself. Other people will do that for you."
— James Cameron (2010 TED Talk*)
*The quote is at the 16:10 mark, but do yourself a favor and watch the whole thing.
Answer: You should read the job ad in the broadest possible sense.
If you are working in a field, there is a natural tendency to read things like job ads (or other descriptions of qualification) in a very narrow sense: While you know something about X, you certainly know a few people who know significantly more about X. Nevertheless, you might be a real expert on X - not compared to those few people, but those might well not apply, but compared to the vast majority of other applicant - which might well make you both an expert on X, and the most qualified candidate.
Of couse, it also depends what the people who wrote the job ad had in mind. There is always the possibility that they had someone specific in mind, or a very specific field. But another possibility is that they thought that field X is fashionable, but they will be rather happy to hire someone who knows lots about X, even though he/she is not among the 10 leading researchers in the field.
Answer: Yes.
Assuming you are actually interested in that job.
Comment: Because the other answers, simple as they are, were still too complicated.


Sudo password doesn't work even if I have no password

Question: I've erased the password from preferencenow I can log in without using any password but when I run a sudocommand terminal ask me a password if I insert nothing or the old one it return error. What's happen?
Comment: Go to Settings > Users & Groups, then click on Login Options and chose yourself as "Automatic login" if this is what you are trying to archieve. Leaving your account without a password is not recommended.
Comment: Is your username preference ? sudo uses the password of the current user.
Answer: sudo requires a password by default on Mac OS X.
Apple's knowledge base article explains more, Mac OS X: sudo command requires a non-blank admin password:

In Mac OS X v10.5 through 10.5.8, if you press the Return key at the
  password prompt without entering a password (even if the user has no
  password, which is not recommended), the command entered will not
  execute and you will be returned to a command prompt.
In Mac OS X v10.6 or later, if you press the Return key at the
  password prompt without entering a password, the message "Sorry, try
  again." will be displayed and you will be prompted for a password
  again.
If your administrator account has no password (a blank password),
  you must give that user a password before using the sudo command.

If you must remove the need for a password to use sudo, you can edit the /etc/sudoers file using visudo command. A thread on macoshints discusses how:

Use the visudo command as root.
Look for the line:
%admin  ALL=(ALL) ALL
Change it to:
%admin  ALL=(ALL) NOPASSWD: ALL

Requiring a password is highly recommended. Removing this check reduces the security of your Mac and exposes your computer to attack or abuse.
Answer: Based off of what you have written so far, I am assuming you are running 10.7 or newer on your computer. When you have Mac OS Lion or newer then sudo actually requires a password either from an Admin account or with a password set up for root user.
If you are no admin then sudo is out of your hands. If you are then your password must be something. Leaving your password empty is not possible of you have to sudo. Temporarily add a password to the account and then proceed. If these tips don't help then please provide feedback with what you are experiencing in greater detail.


Are there any free fraktura fonts available for LaTeX?

Question: Where can I find them?
Answer: You have the yfonts package that provides several styles of Fraktur fonts.  It's quite old and stable and should be part of all the standard TeX distributions (I just checked it is present in TeX Live, but don't have access to MiKTeX).
Comment: yfonts is available in MikTex http://miktex.org/packages/yfonts
Comment: Thanks.  It seemed obvious but I was just too lazy to check it as I don't use MiKTeX myself.
Answer: A good place to look for questions such as this is the LaTeX Font Catalogue.  This page shows how to use a Fraktur font.
Answer: If you are using XeTeX / XeLaTeX take a look at the "Unifraktur" project at http://unifraktur.sourceforge.net
Although the site is written in German language you might be able to find the "download" section.
They offer only 2 blackletter fonts, "UnifrakturMaguntia" and "UnifrakturCook", but these work perfectly with XeTeX.
(These are Unicode fonts, i.e. the "long s" (ſ) is positioned at its official Unicode position. Nothing more is needed for typing a text, especially all ligatures (which are quite essential in blackletter fonts) are automatically set by XeTeX, as long as you don't manually prevent this [wherever necessary] by the usual "no ligature" macro.)
Answer: The LaTeX font catalog has a Blackletter section.  Or if you are using XeTeX or another environment that can deal with TrueType fonts, take a look at Dieter Steffmann's amazing collection of free, historic, mostly German typefaces.
Answer: If you don't mind installing your own fonts (see, for example, Displaying medieval scriptures and neumes in TeX), one of the greatest sources I've found is at
http://moorstation.org/typoasis/designers/steffmann/index.htm
You will find many, many varieties of fonts there, including fraktura, rotunda, textura, Schwabacher, and other more modern forms.
Other, lesser sources include:
http://www.morscher.com/3r/fonts/fraktur.htm
http://www.urbanfonts.com/fonts/BoereTudor.htm
and for non-blackletter
http://www.fontparadise.com/
http://4umi.com/web/font/hand/


Understanding Map Document Properties?

Question: You set up your mxd in a folder.  However, when you copy and paste to a different folder, the Map Document Properties does not update the document path when you save a new mxd with a different title. It brings to the new folder from the previous folder ? I want to change that and how do I do that ?
Comment: generally you don't want to copy/paste mxd documents. (arcmap/arcview has never liked that). There is a save, saveas, and save copy that would help alleviate the problems you are having with the path.
Comment: i'm using 10.2.2. the Map Document Properties updates whether I "Save As" or copy/paste like a regular file. Are you meaning the *data* remains pointed at the old path?
Answer: It sounds like your talking about using relative paths.
You can set the MXD to use relative paths by going to File ---> Map Document Properties and checking the Store relative pathnames to data sources:

If you want this to be the default setting for all new MXDs, you can go into the Customize menu ---> ArcMap Options and on the General tab check the Make relative paths the default for new map documents:

Understanding Map Document Properties?


Same content over multiple sites

Question: I have an account on wordpress. I am writing blogs there. Now I have published my same blogs with same content over DZONE and geekswithblogs.net and few other . Now my question is whether the SEO ranking of wordpress blogs will be hit. If yes then may I know how can I prevent that to happen if I post the same content over the other blogs publishing sites. Can I cross-link (by giving the original link of wordpress) on other sites, will that help me to prevent the SEO hit ? Any other suggestions will be so helpful. Should I stop posting over other sites and remain stick to my original one?
Answer: The best thing you can do is let Google know the original source of the content. If possible, do the following:
1) Use rel="canonical" on the republished articles linking to the original article
2) On the republished articles link back to the original article and cite it as the original source
update
3) There's also a new Google meta tag that may help as well
Comment: May I know how can I cite it as original source ? and can I write full same content in republished one what was there in the original one , I will provide a link(which will point to original) at the bottom of this republished one or I just have to write summary to prevent me from being penalized.
Comment: Linking to it is fine. Making sure your page has a date on it showing it was published after the original article so it will be easier to google to determine which came first. I also amended my answer with another meta tag that would be useful, too.
Comment: Will date be needed? I think Google will guess the date to be the date of it's indexing it automatically. Plenty of articles don't have dates in internet but still we can search those using filters..
Comment: Date isn't needed as far as I know. There isn't any reliable way to know when content was published.

Same content over multiple sites


My dog swallowed a plastic bag of pie. What can I do?

Question: My dog swallowed a plastic bag of strawberry pie. It seems to be a 10×10cm square. He swallowed on Monday morning, and today is Thursday. But he hasn't vomited or pooped it out yet. He is big dog, labrador retriever, and he is eating and pooping well now. But I'm worried about how plastic acts in the body, and I want to find the bag in his poo. What can I do?
Comment: Oh! He poop it today. 6 days after swallow. It's fantastic!
Comment: So glad to hear that!
Answer: You should contact your vet, to make them aware.  The potential for emergency surgery is real.
As pointed out in this Q&A Big hound has eaten corn cobs what can I do to help him pass them?  as long as he keeps having bowel movements and is not gettting sick, he should be fine.  But if anything changes you will need to get to the vet as soon as possible.  Your Vet should give you more direction when you call them.


COBRA and deductibles already paid

Question: If I'd already paid five months of deductible expenses, should I elect for COBRA or buy my own insurance if there's only a $30 difference between the two?
Comment: Which provides better coverage?  They are just 2 options for buying medical insurance. The reason employers *are obliged* to give COBRA is to avoid a "coverage cliff" situation, where you're mid-treatment and suddenly forced to a new plan that doesn't support that doctor and treatment, so you must now reboot with a new doctor and lesser treatment.  But then, your COBRA will forcibly end in a year; you also don't want to get sick and have a cliff *then*.
Comment: Also might be good to keep in mind that when if you switch plans mid-year your deductible will get reset.
Comment: do you know when the insurance for the next employer will start? when did the coverage for your employer end?
Comment: Coverage for prior employer ended today. I have another 60 days to elect COBRA. I'm now self-employed.
Answer: This is kind of a subjective question but there are some common factors to consider.

Is the coverage overall better on the private plan. In many (but not all) cases they are less coverage unless you get a higher plan on the market exchanges.
What is the deductible on the private plan compared to what you have remaining on your COBRA plan? If the deductible remaining on your COBRA is greater than the full deductible on the private plan then it might make sense to go to the private plan. However, if the private plan is higher than the remaining on your COBRA you need to factor in that you will have paid all of the COBRA deductible and will not get credit for it in the private plan.

Ultimately it is a numbers game. You will also want to check that the private insurance has the same network coverage. In other words, you want to make sure you can keep your doctors if that is something that is important to you.
Finally, you not only want to pay attention to the deductible, but you want to compare the max out of pocket overall because that will reset as well.
Answer: @DavidTaylor's answer covers good considerations when comparing the two plans. If you compare those factors and all else is equal, and you've already paid against accumulators in your current plan, COBRA coverage is the best bet since you won't have to start over in terms of paying towards your deductible and max out of pocket.
But, that said - in a comment you clarified,

Coverage for prior employer ended today. I have another 60 days to elect COBRA. I'm now self-employed.

It's important to note that COBRA can be elected retroactively. So, for people who do not have known, imminent medical expenses, the best plan may be to not elect any coverage, and wait to see what happens. If you find yourself with a medical issue during your election window and the cost of the services you need are greater than what your COBRA premium plus your out of pocket cost under that coverage would be, you can retroactively elect the COBRA option, pay the premiums to date, and take advantage of the coverage. But if you never need it, you never pay for it. You're allowed 60 days from the date you receive your COBRA notification to elect coverage, and another 45 days to make your premium payment, so you have significant runway during which to make this decision and incur the premium cost.
Since you mentioned you'll be self-employed from now on, it's clear that COBRA cannot take care of your needs permanently, since it's limited in duration once you do elect it. So, ultimately, you'll need to obtain other coverage if you want health insurance - but, as long as you understand the timelines for election, you can choose to float without coverage in the near future and potentially save the cost of the premium until you settle on your final plan, without any risk of incurring costs that are not covered.

COBRA and deductibles already paid


Send and Receive BTC with Same Address from 1 Person

Question: Is it possible to :
I sent BTC to A from Address1 and I asked him to send me BTC (different amount as I send him) to Address1 (same address with I sent him before)..?
Answer: Yes, this works, change either needs to be sent back to Address A, if the amount is less, or an additional previous transaction output needs to be used if the amount is greater than what was sent from Address1. Here is an illustration of change.
Let's say 1 BTC is sent from Address A to Address B. Then 0.5 BTC is sent from B back to A.
<code>TX #1

Input                         | Output
----------------------------- | ------
(some output 1 BTC to A)      | 1 BTC to B

TX #2

Input                         | Output
----------------------------- | ------
(TX #1 output 1 BTC A to B)   | 0.5 BTC to A
                              | 0.5 BTC to B (change)
</code>

Note this doesn't account for tx fees, which would decrease the change amount back to A
Comment: Oops i meant to say "0.5 BTC is sent from B back to A"!


What is the relationship between dana and tax?

Question: Is dana (or has it ever been) considered taxable in some countries?
Answer: Do you mind an unreferenced answer?
I think the answer is "generally, no"; but that you're asking after any examples, however rare, where the answer has been yes.
Also I guess that gifts of wealth are usually made to an institution e.g. a monastery (as opposed to less-easily-taxable gifts of food and other requisites, given to a monk).

Historically where a country had Muslim conquerors (e.g. India, Afghanistan) there was sometimes a poll tax (a head-tax) on non-Muslims.
There were a few short periods, a thousand years ago or so, where Chinese emperors were troubled by the tax-exempt (and war-exempt) status of Buddhists, and tried to regulate or tax or suppress it
In the Soviet Union under Stalin (e.g. in 1928), they decided that Buddhism (even though atheist) was anti-revolutionary, and taxed monasteries
In Thailand a few years ago there was a proposal to tax monasteries (however I think that was not implemented)
In 1985-1987 Kyoto tried to add a tax to the price of admission tickets which the Buddhist temples sold to tourists


Penalty for refusal to pay Zakat

Question: What are the penalties on a person who refuses to pay the Zakat? Punishment of hell for this sin aside, what are the physical penalties on the person? Only credible answers from Quran, Hadith and Sunnah are welcome.
Thank you..
Answer: The penalty of one who refuses to give the Zakaat out of greed and love of money, then it is on the ruler to take it by force plus half of what he owns wealth, The Prophet ﷺ said:

فِي كُلِّ سَائِمَةِ إِبِلٍ: فِي أَرْبَعِينَ بِنْتُ لَبُونٍ, لَا
  تُفَرَّقُ إِبِلٌ عَنْ حِسَابِهَا, مَنْ أَعْطَاهَا مُؤْتَجِرًا بِهَا
  فَلَهُ أَجْرُهُ, وَمَنْ مَنَعَهَا فَإِنَّا آخِذُوهَا وَشَطْرَ مَالِهِ,
  عَزْمَةً مِنْ عَزَمَاتِ رَبِّنَا, لَا يَحِلُّ لِآلِ مُحَمَّدٍ مِنْهَا
  شَيْءٌ
For every forty camels, one 'bint labun' (a young female camel which
  is two years old and already starting the third year), is due as
  Zakah. No camel is to be separated from the rest of the camels (i.e.
  the jointly owned live stock as mentioned above). Whoever gives it
  willingly, seeking his reward from Allah, will be rewarded. (However)
  if someone refrains from paying it, it will be taken from him (by
  force) along with part of his property (as punishment), for it is a
  right of Allah. None of it is lawful for the family of Muhammad

بلوغ المرام
and on top of that, any group which has influence which refuses to give zakat, then war is declared on them as is clear from the example of Abu Bakr after the Prophet's ﷺ death with those that refused to give zakat.  The Prophet ﷺ said:

"أُمِرْتُ أَنْ أُقَاتِلَ النَّاسَ حَتَّى يَشْهَدُوا أَنْ لَا إلَهَ
  إلَّا اللَّهُ وَأَنَّ مُحَمَّدًا رَسُولُ اللَّهِ، وَيُقِيمُوا
  الصَّلَاةَ، وَيُؤْتُوا الزَّكَاةَ؛ فَإِذَا فَعَلُوا ذَلِكَ عَصَمُوا
  مِنِّي دِمَاءَهُمْ وَأَمْوَالَهُمْ إلَّا بِحَقِّ الْإِسْلَامِ،
  وَحِسَابُهُمْ عَلَى اللَّهِ تَعَالَى" .
I have been commanded to fight against the people till they testify La
  ilaha illAllah (There is no true god except Allah) and that Muhammad
  (ﷺ) is His slave and Messenger, and to establish As-Salat
  (Iqamat-as-Salat), and to pay Zakat; and if they do this, then their
  blood and property are secured except by the rights of Islam, and
  their accountability is left to Allah.

رياض الصالحين (riyadussaliheen)
And as Abu Bakr said, Zakat is of the rights of Islam.
Answer:
One of penalties according to prophet is that the money which didn't spend for zakat, will be spent in the way of evil.

The Prophet said:
من مَنَعَ ماله من الأخیار اختیاراً صرّف اللّه ماله فى الأضرار اضطراراً
بحار

Another one is getting into famine.

The Prophet said:
لاتزال امّتى بخیر ما تحابّوا و اقاموا الصلوة و اتوا الزّكاة فاذا لم یفعلوا ذلك ابتلوا بالقحط و السنین
جامع الأحادیث

Plus, this money couldn't be spent for repair of religious places:

Quran, surat tawbah, verse 18:
The mosques of Allah are only to be maintained by those who believe in Allah and the Last Day and establish prayer and give zakah and do not fear except Allah , for it is expected that those will be of the [rightly] guided.

Removal of blessing.

The Prophet said:
«اذا مُنِعَت الزكاة مَنَعت الأرض بركاتها»
جامع الأحادیث

Refusing to pay zakat is a sign of hypocritical.

Quran, surah tawbah,verse 67:
The hypocrite men and hypocrite women are of one another. They enjoin what is wrong and forbid what is right and close their hands. They have forgotten Allah, so He has forgotten them [accordingly]. Indeed, the hypocrites - it is they who are the defiantly disobedient.

A person who avoid paying zakat is the same as usurer:

Imam Ali (a.s.):
مانع الزّكاة كآكل الرّبا
جامع الأحادیث
Comment: plz take your time to write translations in english too.... plz

Penalty for refusal to pay Zakat


Comma in "last but not least"

Question: I saw that "last but not least" are almost always written without a comma (we could write "last, but not least"). Is it an exception made especially for this sentence or is there some rule allowing us to skip a comma before "but"? Or maybe that's just a very common mistake?
Answer: @Mick is correct, as a fixed phrase it doesn't need to take punctuation as a comma since you would not pause for understanding, although maybe you might pause rhetorically for effect. If you were to pause, the natural candidates would be: "but" a disjunctive, and "but not least" a dependent phrase.
But, if you were, indeed, to punctuate it, you could do as follows:

Please welcome Stephanie, Mark, and -- last, but not least, -- Johnny.

But you could omit the dashes or substitute even more commas, but you don't want to over-comma a sentence... Readability should trump "correctness."

Please welcome Stephanie, Mark, and last, but not least, Johnny.
Please welcome Stephanie, Mark, and, last[,] but not least, Johnny. (most similar to @Mick's example)

At a minimum, we know that one would not use :

X ...and last but, not least...
X ...and last but not, least...
Answer: It's a fixed phrase, and is normally only used in spoken English (i.e. speeches), and with no pause between last and but, so no comma is needed in reported speech.

last but not least
importantly, despite being mentioned after everyone else:
I would like to thank my publisher, my editor, and, last but not least, my husband.

Cambridge Dictionary

Comma in "last but not least"


Job 36 v 4 speech of Elihu to Job

Question: When Elihu states "Be assured my words are not false,one perfect in knowledge is with you" Does Elihu speak of himself?
Answer: It's very unclear who תמים דעות that you translated as "one perfect in knowledge", refers to. There many commentary opinions on this:

Elihu is speaking about Job, saying Job thinks he understands things (Rashi)
Elihu is speaking about himself (An alternate edition of Rashi)
Elihu is speaking about God (Nachmanides)
Elihu is speaking apologetically to God, the comment is an aside (Moreh Chaim)

Textually it's difficult to say. Have your pick.
Comment: ,i feel that your no.3 is my pick but i  would have to change it to read "FOR GOD" as Elihu states in Job 37v 16 "Do you know how the clouds hang poised,those wonders of him who is perfect in knowledge"it appears to me that Elihu has been sent by God,but i cannot fully understand why Elihu has  been introduced into the book just before God speaks.
Comment: forgot to mention that Job 36 v 4 and 37 v 15 is where i draw my conclusion from.
Answer: The account of Job and his friends is an interesting one,  that has deeper spiritual revelation that many of us may have thought. Let's look at the key issues.
Although God describes Job as perfect and upright and one who fears Him, still,  Job had some issues in his life that had to be addressed. God allows Job and his three friends to discuss his position, his affliction etc., at great length before He intervenes. We must realise that all these things happened under the Old Covenant, where God's wrath was kindled against those who opposed Him. Yet there is the element of grace afforded to the four men.
In Chapter 32 a fifth (5) man, named Elihu enters, from nowhere. Not only does Elihu mean, "he is god", but he is also the son of Barachel, whose name means, blessed of God.  Elihu comes as the man of grace. In Biblical Numerology five (5) is the number of God's grace.  Elihu's wrath is kindled against Job, because Job justified himself rather than God. Elihu's wrath was also kindled against Job's three friends, because they had found no answer for Job's dilemma, yet had condemned him.
Clearly Elihu, as the youngest of the four,  comes with
 an apostolic mantle. That is to say, he respects and honours the older men. He holds back his opinions and allows the older men to finish, because he knows in age, there is wisdom. Then Elihu continues to speak on the Spirit of God which is in man that surpasses man's understanding and judgement.
Finally in verse 19 Elihu states that his belly is full of wine (wine is a picture of revelation) as in a NEW wineskin. Jesus said that you cannot pour NEW wine into old wineskins. Meaning that we cannot receive new revelation from God unless we first put on the new wineskin. Take on a new mind.
What then follows from the mouth of Elihu, in chapters 34 thru 37,  is loaded with apostolic doctrine, that is too numerous to unpack.
Elihu then vanishes from the scene and God engages Job for the next four chapters. In the final chapter, Job acknowledges his shortcomings, repents, prepares an offering and prays for his three friends.
In the end Job receives the double portion of a firstborn
 son and dies at the age of 140 ( 2x70) years.
Answer: Earlier in Job 32:8, Elihu makes it clear that

But it is the spirit in a person, the breath of the Almighty, that gives them understanding.

In Job 36:4, he may imply the Almighty's perfect spirit:

For truly my words are free of falsehood; one perfect in knowledge is with you.

Later in Job 37:16, he talks of wonders:

Do you understand how the clouds float, those wonders of Him who is perfect in knowledge?

He connects the wonders with God who is perfect in knowledge.
In the end, God scolded the 3 friends but not Elihu.
Job 42:7

After the LORD had said these things to Job, he said to Eliphaz the Temanite, "I am angry with you and your two friends, because you have not spoken the truth about me, as my servant Job has.

Elihu seems to have spoken the right things empowered by the Almighty's spirit.
Comment: I had forgot all about this question. Thanks for your answer and for reminding me.
Comment: Glad to be of service :)

Job 36 v 4 speech of Elihu to Job


My BTC hasn't shown up in my Wallet

Question: I transferred BTC to my wallet and it hasn't shown up. IT's been 6 weeks and still nothing. I transferred my funds from Binance and Binance is showing that the BTC has been send and received. Bitcoin Core is telling me that it needs to synchronize with the network and is 5 years and 4 months behind. Does anyone have any suggestions as to how to retrieve my BTC? Thank you
Comment: Yes you either need to sync or dump your keys and use them in a different wallet: https://bitcoin.stackexchange.com/a/102078/38618
Answer:
Bitcoin Core is telling me that it needs to synchronize with the network and is 5 years and 4 months behind. Does anyone have any suggestions as to how to retrieve my BTC?

You have not synced bitcoin core full node yet.
If you want to check transactions associated with an address from this wallet or create unsigned transactions:
Create a watch-only wallet in Electrum by using the last option 'Import bitcoin addresses or private keys' while creating new wallet or you can create watch-only wallet in bitcoin core as well if you have it synced on other machine
If you want to sign and broadcast transactions using bitcoin core:
signrawtransactionwithwallet
sendrawtransaction
Answer: It seems you have not let core sync up the the network. Click on the 5 years behind bar at the bottom and it will bring up details on the sync process. Check what the estimated time to sync is. If there is no estimate then give it a few minutes, it can take some time to find peers after starting sometimes. If still no estimate, go to window>peers and see if there are more than a few peers, then see network tab to see if it is receiving data from the network.
If you are receiving data and have a "Estimate time left until synced", then you just have to leave the program running. It can only catch up if it is running.
If you close the program it will stop downloading block data and not be able to catch up. Keep it running and just wait a bit.
If you are not receiving data or have peers then we might need more information to help you. I don't know what your setup is.

My BTC hasn't shown up in my Wallet


Draw text in OpenGL ES 3D game?

Question: I am making a game using OpenGL ES 1.0 and I want to keep player score. So I need to draw text dinamically. What is the best approach? Some library, textures, bitmaps?
I tried to use TextView but when I want to update text I need to do that from main thread, and there is an obvious lag in the game.
Comment: `TextView` ? Are you referring to Android? If so you may want to tag your question with the `android` tag. Also, a `TextView` would be a nice choice, I'm not sure what you mean you need to update it from the main thread, did you try it and there was lag or are you just assuming?
Answer: One common, easy way to do it is to simply make a texture atlas with the characters you'll need (probably lowercase letters, uppercase letters, numbers, and maybe some punctuation). Then simply pull out the section you need to draw each letter.
Answer: The typical way is to use a texture atlas with glyphs.
Personally, I am a fan of vector text, where you actually define the shape of the character with geometry, not with texels.
The advantage of this is that your text is completely resolution independent.
You can zoom in on your text as far as you like, without every seeing aliasing or jaggies.
Now granted, the curves in text means that they will look best with curve primitives, or high poly counts.
But if you are OK with crude shapes, and want a simple approach, may I suggest Dutch Blunt?

DISCLAIMER: I am the author.
For a more professional solution (paid) you can look into Slug.

Draw text in OpenGL ES 3D game?


Can the exchange get my ether in any way

Question: I send some ether from exchange A to B via smart contract, however the latter does not support smart contract at moment, is there any way to get those ether back?
Answer: What is the recipient address, a "normal" account, or a smart contract itself?
If it is a normal account, then the owner (exchange) holding the private key, can send the ether back.
If the address is a smart contract, then it will depend on whether the exchange has provided ways of getting the ether out (what is supposable).
Can you provide more information please, so we can have a deeper look?
Etherscan links, transaction...
Answer: You have to ask with B exchange's support. There's nothing else you can do about it.
It is likely exchange B has a system that tracks when it address receives ether. And this system do not support "internal transactions", ie when a contract is sending ether.
But your ether was credited immediately when the transaction was confirmed in the blockchain. So it is available in their recipient address.
They may be able to manually verify the transaction and credit the ether in your account. To return your ethers is probably harder because you used an exchange address, they have to be sure you are the owner.


PPT to PDF converter in UNIX

Question: I am trying to convert a ppt file to a pdf file in command line. I have tried unoconv but it screws up the layout. Is there any open source utility that is able to this without messing around with the layout?
Answer: Keep an eye on this thread -- it doesn't have any suitable solutions yet, but covers common ground.
You should keep in mind that PPT is a proprietary format.  Even OpenOffice, a fully functional open-source office suite, has problems with formatting & laying out PPT files sometimes.  This is even before handling things like animations, etc.  Your best bet is probably to use a Windows machine (argh) with MS Office (argh) for the PDF export.

PPT to PDF converter in UNIX


ios networking code in the model?

Question: I recently watched the 'Network Apps for the iPhone OS' videos for WWDC 2010 in iTunes U and the speaker said that the best place to write your networking code is in the model.  This kind of confused me because I have always placed this code in the controller classes.  Can someone please explain why this is the best place for the networking code?  Also if possible please provide an example, code or pseudocode, either works.
Answer: I wonder if we're all using the same terminology? Here's what I would use and I think (though I'm saying this without much context) what the WWDC presenter meant:

Model. The data
View. What it looks like in the UI
Controller. The layer than mediates between the Model and the View

Using these definitions, the controller is a terrible place to keep any networking code. It has nothing to do with the interaction between the UI and the data.
Of course there's no reason why you couldn't have multiple classes for your model: one for the data representation and another to mediate between your web service and your data model. In this sense it would be a controller but would, nevertheless, be in the model layer of the application.
Comment: I'm referring to networking code that would for example, download records to sync with core data or something like that.  So should the networking code for this go in the model classes.  I thought model classes were mainly domain objects used to represent data, I don't understand where the networking fits in there. Does he mean maybe some sort of manager facade that can do this, and perhaps he means that this class would be in the model.  I think I maybe confused with where in the model this code should go and what classes actually represent the model.
Comment: I think your definition of the model is too narrow. I would say that the model is code that works with the data without regard to how it works in the UI. This means that the networking code is in the model _layer_ but not necessarily the same _class_ as your domain object.
Comment: OK cool so I was just getting too hung up on the model being the domain classes, thanks +1
Answer: I think the model is an extremely terrible place to implement any kind of networking code. Since networked operations should proceed in an asynchronous fashion, a controller object is best suited to handle the complexities related to firing off requests and handling the response. It does make sense for a model object to know how to construct itself from downloaded data (XML or JSON, for instance), but most of the services code I've seen in model objects is poorly-written, synchronous networking.
Answer: Hmmm... that does seem to be a fairly odd remark, but then again, maybe it's valid in some contexts. Certainly, I know my models end up having a lot of networking code in them;
That is, the Model should handle everything having to do with the data and accessing it. That necessarily means that the Model will include the code to connect to whatever the backing store is for the data.
Parts of the Model might not have networking code in them at all, if the data is local. But consider that networking code is used to transfer data from somewhere to somewhere else; If you are coding based on Models first, it will probably follow that pretty much all of your networking code will end up there.
Answer: What is call Model in this post is in fact the Domain Layer and not the data container used between controllers and views
Network operation are generally asynchronous and your model is most likely to be present to handle response while you controller could have been destroyed by your navigation between the request and the response. That could crash your application because the delegate (the controller in your case) is no more present in memory and at least create memory leak because the delegate is generally responsible to release the connection object.
Comment: The answer here is to ensure that the controller objects can cancel any inflight requests, and/or use singleton controllers that can manage a large set of requests from multiple sources. In fact, I would argue the exact opposite from what you've suggested – model objects should be much more transitory than controller objects, since they should only exist to represent small slices of data in the application.
Comment: The confusion comes from the fact that MVC bring the concept of Model for views that I call "view model" and I thing you refer to this when talking about the Model while what I call Model (VS ViewModel) is in fact what is sometime call domain, repository, business layer, ...  I obviously totally agree that network code does should not happend in viewModels which are basically data container.
Answer: The "networking is best done in the model" is as you say explicitly mentioned by Apple's networking guru Quinn The Eskimo during the WWDC 2010 session. Having recently completed two fairly major apps with comprehensive networking, I am very keen to try something different on my next project, in line with Apple recommendations.
However, it's a strange thing that in general you can find tons of resources on iOS development, but with this I have really struggled to find any information. That is, searching on iOS networking architecture, and networking in the model, and so on. That was until I recently posted a similar question on Apple's dev forums. Quinn provided a very helpful response. You can read it here: LinkedImageFetcher and Network Code in the Model
Quinn pointed out that the best sample to demonstrate this is MVCNetworking
Also, that despite not having had the time to update the sample with Core Data, NSURLSession, and so on, he still feels that "the basic architecture of MVCNetworking is fairly sound."
Finally, this post was also referenced; looks like it has some really great links:
MVCNetworking on iOS 5
Answer: Networking, parsing, ecc...surely go in the Model part of an app...For model i mean the part of the MVC pattern not strictly on the model representation object.
I'll think to build a structure like so:
When the controller ask for some data to the model, it has a dependency to a kind of Network Manager, now the only think model have to do is invoke a method in it (specified in a protocol) and wait for the response (obviously async).
The Network Manager has a reference to a specified class that is responsible to make the network call and return a raw data, when a completion block is fired the Network Manager gives that data to a Parser object (obviously with a method specified in a protocol), wait for the response and when the data is retrieved and parsed returns the array, dictionary or what you need to the model with the new data updated in it, after all this can pass back to the controller to make a reloadData or something like so and update views with updated data.
I hope would be helpful.

ios networking code in the model?


Car model does not render after using motion tracking, but its visible in viewport

Question: I am fairly new to Blender.(I am an experienced Maya 3D artist) I'm using version 2.83 on an iMac. I have rendered simple 3D models before using blender and the Eevee engine. But I need to test motion tracking and photo realistic 3D car rendering for work. I have followed a good motion tracking and rendering tutorial on youtube, but since I have the motion tracking figured out and scaled correctly with my car model, it will not render. If I add a sphere to the scene it will not render. The only thing that shows up in my renders is the image sequence background that I used for the motion tracking. I have checked my render layers, the car is render enabled. The Cycles render engine is selected. I can see the car in the viewports, but it never renders! Can someone please help? I am attaching a screenshot.
Comment: Did you press f12 to render? Also read: https://blender.stackexchange.com/a/108876/92768
Answer: When you press "setup tracking scene" after solving the camera movement, blender creates two collections: a foreground (with a cube as reference) and a background (a plane to catch shadows).
You can safely delete the background one if you don't need a shadow catcher.
See: https://blender.stackexchange.com/a/108876/92768
Comment: Thanks for the reply, but I think I figured out the problem. It seems that I started my motion tracking project having already had a car model in my scene. When I followed the motion tracking tutorial it disabled the render abilities for the car model somehow. So I started the tutorial again with an empty scene, and then appended my car model into the scene after the tracking and camera solving. This worked! I can now render my car and its shadows.
Comment: @LemonHat all that you need to do is incorporate the collection where the car is to the rendered collections, or add a node in the compositor to have the contents of the collection where the car is so that the information can be available for compositing. No need to do things over.


Do I need to show a return ticket to the immigration officer in UK?

Question: I will be flying from New Delhi to Manchester soon and my return dates aren't fixed yet. Do I need to show a return ticket to the immigration officer when asked at the port of entry?
Comment: @phoog indeed yes they can satisfy the IO, The IO is *always* entitled to challenge (that's an absolute), but the outcome is almost wholly governed by personal impact and articulation skills. Most will have a ticket, but some will not and rely on their personal impact.  The person can also establish themselves as a high-net-worth individual.
Comment: Unless you are a high-net-worth individual, then yes absolutely. The IO can l examine your ticket as part of the landing interview.
Comment: Almost certainly yes - you have to have proof that you can exit the UK and not become a burden on the state.  A ticket however does not *guarantee* you entry.
Comment: @GayotFow can an applicant for entry as a visitor, with uncertain return dates, satisfy the IO by some other means than a return ticket?
Answer:
Do I need to show a return ticket to the immigration officer when asked at the port of entry?

No. UK does not require proof of return/onward travel as a matter of routine and if you don't have such a ticket you can't produce it on request at a border.
However, it is not very likely that you will be asked for a return ticket unless there is some doubt about your returning and then having a return ticket should help. So (a) it would be sensible to have one if you can and (b) you must definitely show it if asked and you do have one. Denying you have such a ticket that then turns up during a search is an invitation to be sent straight back to wherever you came from.
Depending upon your circumstances you may be able to persuade the IO that, while it is certain you will depart UK in good time, there is a good reason you have deferred purchase of your return ticket. This might be that you will return home directly unless you hear within a few days that you are invited to speak at a conference in Country X in a fortnight, so would in that case book your return via Country X rather than direct.
Comment: "you must definitely show it if you do have one": do you mean to say that the traveler should volunteer to show it?  I would advise to show it only if asked.


admin panel url not working after installing magento 2.2.5

Question: i have installed theme based on magento 2.2.5 storefront looks good but admin panel is showing this error:
Object not found!
The requested URL was not found on this server. If you entered the URL manually please check your spelling and try again.

If you think this is a server error, please contact the webmaster.

Error 404
localhost
Apache/2.4.33 (Win32) OpenSSL/1.0.2o PHP/7.0.30

I tried to download the xdebug and add this zend_extension = "C:\newxampp\php\ext\php_xdebug-2.7.0alpha1-7.0-vc14-nts-x86_64.dll" to the bottom of the php.ini file but url showing the same error.
Answer: Just copy .htaccess file from Pub folder to root.


How do you implement a front-end contract with back-end functionality in Solidity?

Question: How do you create a front end contract that calls a back end with the idea of being able to upgrade or change the back end contracts without having to redeploy the front end contracts?
Answer: There are different approaches at Upgradeable smart contracts
One of the simplest is for the frontend contracts to refer to the backend contracts, not as hardcoded addresses, but using ENS (https://ens.domains).  The ENS entries are updated when new backend contracts are needed.
Note that a significant benefit of smart contracts is their trustlessness, and upgradability can break that trust significantly, for example:
https://medium.com/consensys-diligence/upgradeability-is-a-bug-dba0203152ce
Comment: As I understand it would be versioning of each front contract where back-end contract's storage would remain untouched. But this will bring high additional gas consumtion to get the back-end contracts' storage from the front-end contract.
Answer: In case back-end contract is stateful and ought to preserve its state during upgrade, then usual practice is to deploy two-layer back-end contract.  First layer is a proxy contract that keeps storage and delegates serving almost all calls to the second layer contract.  The address of the second level back-end contract is stored in proxy's storage and could be changed.  The proxy contract may look like this:
contract BackendProxy {
  address private backendImplementation;
  address private owner;

  constructor (address _backendImplementation) public {
    backendImplementation = _backendImplementation;
    owner = msg.sender;
  }

  function () external payable {
    if (msg.data.length > 0) {
      address oldBackendImplementation = backendImplementation;
      address oldOwner = owner;

      bool status;
      bytes memory data;
      (status, data) = backendImplementation.delegatecall (msg.data);
      require (oldBackendImplementation == backendImplementation);
      require (oldOwner == owner);

      if (status) {
        assembly {
          return (add (data, 0x40), mload (data))
        }
      } else {
        assembly {
          revert (add (data, 0x40), mload (data))
        }
      }
    }
  }

  function setBackendImplementation (address _backendImplementation) public {
    require (msg.sender == owner);
    backendImplementation = _backendImplementation;
  }
}

So proxy contract delegates everything to backendImplementation except for changing address of backendImplementation (to make sure the owner will not loose contract by pointing proxy to wrong implementation, and except for transfer with no data (which, once delegated, would not fit into 2300 gas stipend).  The address of the proxy contract remains stable, while implementation may be changed by the owner at any time.
Answer: There are two leading approaches and a variant that works in some cases.

Eternal Storage: Persistent storage contracts that are "owned" by front-ends. The idea is the front end might change from time to time and the stored data should persist. I think this was the first succinct description of the pattern. https://blog.colony.io/writing-upgradeable-contracts-in-solidity-6743f0eecc88/. You could use ENS to address the evolution of the front-end addresses.
Proxy contracts: The Proxy holds the state and uses delegatecall to fetch and execute code that can be changed by adjusting the address it uses to fetch the code. I believe this is more popular of late. It's trickier and more prone to error so be sure to understand what's happening and the security pitfalls before using in production. https://medium.com/@daonomic/upgradeable-ethereum-smart-contracts-d036cb373d6

As Eth (above) and Steve Marx described in https://medium.com/consensys-diligence/upgradeability-is-a-bug-dba0203152ce, upgradeability undermines immutability, so one ought to carefully consider the desirability of enabling such a possibility - how it re-introduces centralized control and defeats assurances that might be important to users.
In some cases, you might consider trustless upgrades. This pattern puts the upgrade decision in the hands of individual users. The centralized authority is the issuance of compatible versions. The users decide, for themselves, if they want to upgrade or stick with the original contract. It works in cases where it is not necessary for all users to work with the exact same implementation and ABI, e.g. profileV1 and profileV2 with extra features. It would probably not work for something heavily-dependent on uniformity like a token, but many of those cases are strong candidates for no upgrades at all. https://medium.com/hackernoon/trustless-upgrades-in-solidity-bf0bd4047d28
Hope it helps.


Help With Houseplant Identification

Question: I recently purchased this houseplant, but do not know what it is. Can anyone help with ID? US dime for scale.
Answer: I suppose is a Lycopodium (or in any case some species in the same family).
It is a link between mosses and vascular plant. It is still vascular, without flowers but with spores. Not a fern, but defined "Fern ally" (like few other families which very few species, that nobody want to classify correctly).
Note: I could be wrong. Some mosses could be similar (but branches are too long), and also some flowering plant could have similar look, when they are small. On the other hand, I do no remember good-looking (so for pots) flowering plant.
Answer: I found out what it is! Couldn't ID farther than Selaginella sp. but that's enough to call it a spikemoss.

Help With Houseplant Identification


Using LDA in non-realtime twitter data

Question: I'm trying to understand user characterization from twitter data. How can I infer a user's interests from their status updates? LDA (Latent Dirichlet Allocation) seems to be a suitable approach to topic modeling, based on my reading. I've collected data, removed stop words and punctuation. However, I don't have any training data or example topics. Do I need to specific a topic list for lda? Also, which is the best java library for me?
Answer: You might want to look at the Java package jLDADMM.
jLDADMM provides implementations of the LDA topic model and the one-topic-per-document Dirichlet Multinomial Mixture (DMM) model for modeling topics on normal or short texts
Applying topic models, such as LDA, for short texts (e.g. Tweets) is more challenging because of data sparsity and the limited contexts in such texts. One approach is to combine short texts into long pseudo-documents before training LDA. Another approach is to assume that there is only one topic per document like in the DMM topic model.
Answer: Part of the beauty of Latent Dirichlet Allocation is that you do not specify the topics a priori. Instead, the topics are discovered in tandem with the topic assignments themselves. In other words, you do not need a specific topic list for LDA.
As for Java libraries, one of the most popular tools which implement LDA is MALLET, which was produced by Andrew McCallum. The quick start includes information on how to get started with topic modeling using the toolkit.
Answer: You don't need to specify an a priori list of topics, but you do need to specify the number of topics you'd like the algorithm to find. With a diverse data set like twitter updates, this is going to be a tricky process. I recommend randomly sampling a set of data on which to perform parameter optimization experiments, to see which topic number setting appears to give you the best results, then using the selected parametrization on the remaining data. GraphLab has some nice java-based LDA functionality, but you'll have to do some manual pre-processing with your data to get it into their expected format. Their topic modeling documentation is pretty straightforward, and should give you a nice overview of the typical experimental workflow for topic modeling studies.
Answer: Take a look at Vowpal Wabbit software package. It scales even to very big datasets.
From my experience with short documents (not tweets though) it is difficult to make sense of the topics and document clusters that you will find. The clusters of short documents I obtained from my real world data were really complicated. The best results were obtained if some prior information or higher level features are added. Although this was hard, the clusters obtained were much easier to interpret.
For visualization of how the documents cluster after LDA (each document expressed as a distribution over topics), I used SOMOCLU and ESOM. Both are the methods of dimensionality reduction and are useful for visualization purposes.
LATE UPDATE: Working with topic analysis for short texts, it is better to work with term-term representation rather than the standard document-term representation. The extracted topics for my short texts were of better quality (subjective).

Using LDA in non-realtime twitter data


Update Google Results to https

Question: My server manager updated our site to use https site-wide. Now all of our search results redirect to the home page. We don't want to lose our ranking, which is currently very high. How can I fix this?
Answer: I found the answer: https://magento.stackexchange.com/a/107086/26062
I added the following to .htaccess
<code>RewriteCond %{HTTPS} off
RewriteRule ^ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301,NE]
</code>
Comment: Feel free to accept your own answer, perfectly allowed by the agreements here.

Update Google Results to https


Is it necessary to unit test ActiveRecord validations?

Question: Is it necessary to unit test ActiveRecord validations or they are well-tested already and hence reliable enough?
Answer: Validations per se should be trustable, but you may want to check if the validation is present.
Put in other words, a good way to test something is as if it were a black box, abstracting the tests from the implementation, so for instance you may have a test that checks that a person model can't be saved without a name, but don't care about how the Person class performs that validation.
Answer: It should be sufficient to accept that libraries such as ActiveRecord are better-tested by the developers than they ever will be by you: for them it's a primary concern, for you it's at best tangential.
That's not to say there won't be bugs - I found a small one the MS SQL Server adapter once a long time ago - but the kind of test you're likely to be implementing is highly unlikely to expose them as they're most likely to be edge cases. If you do find a bug, of course, it's probably very helpful if you report it with a test case that exposes it!
I would only test ActiveRecord internals if I was seeking to understand better a particular aspect that the library implements. I would not include those exploratory tests in any application project, since they're not really relevant to the project.
In general, you should write tests for code that you write yourself: if you live or try to live in a TDD world, the tests should be written before. If your models have validation rules then you should almost certainly write tests to ensure the rules are present. In most cases, the tests will be trivial, but they'll really be useful if a line inadvertently gets deleted some time in the future...
Answer: As Mike wrote, at the very least you should test that the validation exists. It's just a bit of double-entry accounting (sanity check) that is easy enough to do.
Depending on the situation, you should also test that your model is valid or invalid under particular circumstances. For example if your field requires a certain format, then test the example formats that are valid and those that aren't. It's much easier to see what this means by reading a few examples in your tests:
<code>class Person < ActiveRecord::Base
  validates_format_of :email,
      :with => /\A([^@\s]+)@((?:[-a-z0-9]+\.)+[a-z]{2,})\Z/i
end
</code>
Yes, the validations are well-tested and reliable enough. But your correct use of the validations is what you want to verify.
Answer: As a side note, Ryan Bigg's blog post has_and_belongs_to_many double insert mentions someone encountering a bug in ActiveRecord (not validation related, though). As he points out, don't assume Rails can't possibly have a bug, because we know there are 900 open tickets for Rails.
But yes, the main reason you'd write a test is to check that your use of ActiveRecord is correct.


What does "disciplinary action" usually mean?

Question: I had worked at a call center, and hung up on a customer who was swearing at me. He called back and complained to management and they said there may be "disciplinary action". They ended up firing me for just cause (which I'm still considering taking to the labor board) but I'm wondering, what does "disciplinary action" usually mean? Would it mean having to write an apology letter? Or is it really a euphemism for getting fired?
Comment: Frequently being cited for disciplinary action can lead to firing. I remember your story from before and I do not believe you were fired for hanging up on the caller but rather you were fired for not accepting being disciplined for it. You continually brought it up to the manager even though he/she told you how they work and you refused to accept it. That's a major difference.
Comment: @Dan Why do people on here keep saying I was fired for asking too much? I asked my manager once.
Answer: Copying word for word from uslegal.com:

In employment law, disciplinary action is a process for dealing with job-related behavior that does not meet expected and communicated performance standards. The primary purpose for discipline is to assist the employee to understand that a performance problem or opportunity for improvement exists. The process features efforts to provide feedback to the employee so he or she can correct the problem. The goal of discipline is to improve employee performance.

Some methods of disciplinary action may have an employer:

Verbally reprimand the employee for poor performance.
Provide a written verbal warning in the employee's file, in an effort to improve employee performance.
Provide an escalting number of days in which the employee is suspended from work.
End the employment of an individual who refuses to improve.

If you are from another country, you can just look it up on your favourite search engine.
Answer: Disciplinary action involves deciding how to punish/correct you for doing something you should not have done as it conflicts with legal or company policies. Chances are your company has a rule in place which says you cannot hang up on a customer under any circumstances. We cannot know for sure unless you can enlighten us.
The next step is enacting the decision made by your superiors. It can be anything from a metaphorical slap on the wrist to being fired. 'Disciplinary action' is never a guarantee that you are getting fired. It will be up to the company to decide if your actions warrant such a severe punishment. It may vary depending on your country, but writing an apology letter - either to the company or the customer - seems unlikely. If you have been fired, your involvement with the company has come to an end, and unless you are pursuing further action with your labor board, further communication would probably be discouraged.
Comment: Out of curiosity, what other forms of "punishment" is there before firing? Does disciplinary action just mean "get a stern talking to"?
Comment: Other forms could include reduced privileges, reduction of bonus payments,  be monitored by a superior more diligently or an extending of probation periods. A verbal warning is always possible too. Whether or not it gets kept on-record is for the bosses to decide.
Comment: *Especially* if OP is pursuing further action with their labor board, further direct communication would likely be unwise.
Answer: Depending on the severity of the infraction, and the work history of the employee, you can expect the response to vary.
Typically these policies are outlined in a corporate document, such as an Employee Handbook.  Usually the language says something along the lines of: "...may be subject to disciplinary action, up to and including termination of employment"
Not all disciplinary action ends in termination of employment.  Often, if the company wants to try to retain the employee, they will implement what is called a "Performance Improvement Plan."  The PIP will outline the problem behaviors, and set a plan for how to resolve the issue.  The problem employee will usually have a set period of time to show a change in behavior, or be terminated.
If the infraction is severe enough, or the employee isn't someone that management wants to retain, you may be dismissed without a PIP or any opportunity to address the problem.
Comment: @Lumberjack - There is more to the [story](https://workplace.stackexchange.com/posts/104046/revisions) then the author explained in this question.
Comment: the company had monthly PIPs for everyone, so I get the impression they wanted to be ahead of the ball if they needed to fire someone
Comment: Yikes!  What a nightmare!  It sucks to lose your job, but in the long run it sounds like you'll be better off.
Comment: @Ramhound how is that relevant?
Comment: All I did was, there is more to your situation, that you described in this question.  Have a problem with that?  Feel free to report the comment as noise.
Comment: @Ramhound Why did you post a link to the revision history rather than the question itself?
Comment: Because that question was edited.
Comment: @JAB If you check out the original question, it was very heavily edited.
Answer: disciplinary action usually means some form of official and documented action to sanction unwanted behavior.
This may be a written warning or a official instruction from you manager, that goes into your file with HR. This is usually the first step to document cause for firing when the offense is not in it self big enough to fire immediately or the employer wants to give you a second chance. Firing is only the ultima ratio of a disciplinary action.
Remember firing is usually also a loss for the employer, since he invested money to hire and train you. So this is usually the least desiderable outcome for both parties. But other than threaten to fire you, the is not much the employer can really do. So this serves two functions: Possibly correct your behavior - and if it is not likely this will succeed or if they want to make an example: Make firing as cheap as possible by having proof for the alleged cause.
As, in my experience, call centers often have trouble with staff discipline, immediate firing on the least offense may just be company policy.
Answer: Usually, the phrase appears in this deliberately vague terminology  "Disciplinary action up to and including termination may result".
What that means is that they can do anything from a verbal warning to firing you.
The reason they phrase it so vaguely is to give themselves the widest possible latitude.  If you have a good record and many years of service, it may be a warning, if you have previous infractions, short time working for the company, bad attendance, or the manager doesn't like you, or any of the above, they can get rid of you.


Identifying documents similar to specific clusters

Question: Through performing clustering on a set of 1,000,000 text documents, I have identified 100 clusters. I am particularly interested in, say, 10 of the clusters. Imagine, I now have an additional set of 100,000 documents (not part of the initial 1 mil documents). I wonder if there is a way to efficiently check whether each one of the 100K new documents belongs to one of the 10 clusters.
Answer:
First Idea: Go as usual. Calculate the distance according to of each new document to the centroids of 100 clusters and see to which cluster the belong (minimum distance wins).
Second Idea: You already know which clusters are your targets. Assign a label (e.g. 1) to these 10 and and another label (0) to the rest 90. Then train a classifier and try to predict the label for new documents. (The process of labeling in supervised learning is usually based on expert annotation i.e. an acceptable accuracy in labeling. But with this method you lose that accuracy so expect that not all the labels are perfectly fine as a clustering algorithm is blindly do that)


Strategies for Bob Jenkins

Question: I'm playing Arkham Horror for the first time and I randomly drew Bob Jenkins as my investigator. With some of the other players' characters, their "purpose" is pretty clear. There's the guy with high fight who starts with a sweet weapon, the guy with high lore and tons of spells, etc. With Bob, I'm not seeing a clear path to how I can best contribute. What type of strategies or tactics should I be employing to make the best use of my turn?
Answer: Bob Jenkins is:

Rich!  $9 -> Go shopping for Unique Items
Has stuff: 2 common and 2 uniques, hopefully he starts with some good stuff
Well rounded: 4 Sanity and 6 Stamina is a great split.  Enough Sanity to allow missing a horror check or two, and enough stamina to get down and dirty.
Reasonably fast - speeds 4 and 5 are not out of the question.  Bob can get from place to place quickly.
Has a strong will, minimum 3
Can hopefully compensate for his somewhat poor fight skill with some good items

When playing Bob, you should be aggressive.  Bob has the stats and should have the items to allow him to survive most bad things.  If you get lucky and start with an Elder Sign, go off world as quick as you can.  If not, see if you can buy an Elder Sign, or start grabbing clue tokens.  Favor the locations where common items are found to take advantage of the Shrewd Dealer ability.  Bob may not be the best investigator at any particular thing, but odds are, he is the second best at most things in a normal group.  Use him to fill in for whatever your team is lacking.
According to the Arkham Horror Statistics Report, Bob has the 7th highest winning percentage (out of 48 characters) in October 2010.  For November, he has moved to 6th.
Comment: I think I got a bad initial draw for the random items. Everything is a tome that requires a Lore (-1) check. I'll just have to head over and get more unique items.
Comment: @Jonathan - Tomes aren't that great for Bob.  You can always meet up with a fellow investigator with a higher lore and give them the tomes.  If they can give you a nice weapon at the same time, then everyone gets better.

Strategies for Bob Jenkins


Is it a good idea to publish a research paper about the simulation of BB84 protocol?

Question: I'm an engineering student. As my end of year project I've simulated BB84 protocol using simulaqron(python). I'm thinking about publishing a paper about this simulation.
I haven't published any research paper before, do you have any suggestions about where to publish? or about how to represent my ideas?
Comment: I'm an engineering student. And I'm also thinking of doing my project on BB84 protocol but I don't know where to start.
could you please provide me with the documents and references or anything that helped you in your research?
Answer: First of all, it depends on the level of detail of your simulation. SimulaQron does not take into account noise, so I presume your simulation is only functional. Many BB84 functional simulations have been developed so far, and no one was so interesting to deserve publication in a research paper.
Notice also that BB84 is the reference example in the following tutorial by the authors of SimulaQron:
http://www.simulaqron.org/wp-content/uploads/2019/04/instructions_2018_2.pdf
If you want to simulate BB84 in a detailed fashion, you may try QuISP, a novel simulation tool whose focus is "on protocol design and emergent behavior of complex, heterogeneous networks at large scale, while keeping the physical layer as realistic as possible."
Comment: Thank you for your suggestions! but with Simulaqron we can simulate noisy qubits.             In my simulation I used cascade protocol for error correction with noisy qubits.
Comment: This is very good news! Can you provide a link to the documentation of the simulation of noisy qubits?
Comment: this is an example https://softwarequtech.github.io/CQC-Python/qber.html?highlight=noise , but now I find that This noise is probabilistic  and  should not be used to benchmark the performence of protocols in noisy settings. As a beginner I didn't pay attention to this detail before :)