How to run an obfs4 bridge?

Question: I want to help censored users. How can I run an obfs4 (Pluggable Transport) bridge on a Debian-like GNU/Linux machine?
Answer: The Tor Project's official guide is available here. It has instructions on how to set up an obfs4 bridge for several platforms, including Debian and Ubuntu. Don't forget to make sure that your OR port and your obfs4 port must be publicly reachable. Tor automatically tests its OR port but it currently (as of August 2019) does not test its obfs4 port. You can use this scanning tool to make sure that your obfs4 port is publicly reachable.
Step 0: Follow this guide to setup the official package repository, and install Tor.
Step 1: Edit your sources.list to add obfs4proxy repository:
Note: you can skip this step if you're running Debian stable (jessie) or more recent.
deb http://deb.torproject.org/torproject.org obfs4proxy main

Step 2: Install obfs4proxy:
$ sudo apt-get update && sudo apt-get install obfs4proxy

Step 3: Edit your torrc config file, usually located at /etc/tor/torrc
#Bridge config
RunAsDaemon 1
ORPort 9001
BridgeRelay 1
ServerTransportPlugin obfs4 exec /usr/bin/obfs4proxy
ExtORPort auto
#set the Nickname and Contact info
ContactInfo <your-contact-info>
Nickname <pick-a-nickname>

Step 4: Restart Tor
$ sudo service tor restart

Step 5: Check the logs and confirm the ORPort is reachable and the obfs4proxy is working.
$ sudo tail -F /var/log/tor/log

You should see something like this:
[notice] Registered server transport 'obfs4' at '[::]:46396'
[notice] Tor has successfully opened a circuit. Looks like client functionality is working.
[notice] Bootstrapped 100%: Done
[notice] Now checking whether ORPort <redacted>:9001 is reachable... (this may take up to 20 minutes -- look for log messages indicating success)
[notice] Self-testing indicates your ORPort is reachable from the outside. Excellent. Publishing server descriptor.

Comment: The "ExtORPort auto" above is fine -- the extended ORPort is for local connections, and you don't need to open anything in your external firewall. That said, if you want to pick your obfs4 port number, you could add a torrc line like "ServerTransportListenAddr obfs4 0.0.0.0:52812". But diversity of obfs4 ports is actually really important, so I'd argue against any instructions that will lead people to using the same port.
Comment: I would argue for specifying a port number rather than using "auto". That way you know what to allow in your firewall settings.
Comment: Extended ORPort is the port used by extended transport plugins to listen to inbound connections, not for Tor to connect to such plugins. The network connection between Tor and extended plugins is random and there's no setting to specify them, ALAIK, and each plugin uses its own port. If we have obfs3 and obfs4 enabled, they use 2 ports.
Comment: In example, if we use `ORPort 8443` and `ExtORPort 443`, normal/unobfuscated Tor connections will come to port 8443, and connections using both obfs3 and obfs4 obfuscation will come to port 443. I don't see why ORPort can be set and ExtORPort should be random. ExtORPort *is* used by outside world and *needs* to be forwarded on router. For guard relays, it's also more helpful to use a HTTPS port to help make you look like an average website in the world, than a whacky port that will probably be blocked on Tor user's network.
Answer: Great explanation, it helped me a lot. Like to add the following; These days I do not see a lot of obfs4 traffic yet. If you want to publish as an obfs3 AND obfs4 bridge relay you can change the line
ServerTransportPlugin obfs4 exec /usr/bin/obfs4proxy

to
ServerTransportPlugin obfs3,obfs4 exec /usr/bin/obfs4proxy

You only need to install obfs4 as mentioned in the post above. obfs4 is backwards compatible with obfs3.
When you start up your bridge, you will see something like this in your logfile;
Registered server transport 'obfs3' at '[::]:41234'
Registered server transport 'obfs4' at '[::]:44321'

Leave your ExtORPort set to auto for  diversity reasons. I have a firewall enabled on my Debian bridge with very restrictive port settings. I had to make port forwards for the given obfs ports in iptables (easy with gufw) as well as in my hardware (internet-)firewall to make things work. So I am not so sure that the ExORPort is for local connections only as mentioned by Rodger (please let me know if I am wrong here). The obfs3 and obfs4 transport ports Tor chooses for you will be cached, so after booting your bridge you keep the same ports. Hope this helps.
Tor needs bridges, be a bridge if you can!

How to run an obfs4 bridge?


superblock errors?

Question: fsck /dev/sda
fsck 1.42.1 (17-Feb-2012)
e2fsck 1.42.1 (17-Feb-2012)
/sbin/e2fsck: Superblock invalid, trying backup blocks...
/sbin/e2fsck: Bad magic number in super-block while trying to open /dev/sda

Hi, I had an XP installed for years, never a problem besides those created by Win crap. Installed Ubuntu 11.10 about 15 days under a new 5gb partition created by the Ubuntu installer. Everything ran just fine.
Trying to open a Gparted since about 1 week, it always says that I dont have any partition, and that's all about  whole drive unallocated space
I need to take about another 5 gb from the windows partition into the linux partition with GParted but I can't just do anything. I just ran fsck command on /dev/sda and I got that 'superblock' stupid message which I can't understand. And EVEN in the case its an error indeed its an error created by the Ubuntu installer while installing itself in the new partition created
fdisk -lu shows me:
Disk /dev/sda: 35.9 GB, 35939409408 bytes
240 heads, 63 sectors/track, 4642 cylinders, total 70194159 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xcccdcccd

Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *          63    57471119    28735528+   7  HPFS/NTFS/exFAT
/dev/sda2        57462782    70187039     6362129    5  Extended
/dev/sda5        57462784    68622335     5579776   83  Linux
/dev/sda6        68624384    70193151      784384   82  Linux swap

How can I do to fix the 'superblock' issue ?
After some research, I found out fsck doesn't work on ntfs-based filesystems. After installing ntfsprogs through sudo apt-get install ntfsprogs it seems it worked.
sudo apt-get install ntfsprogs
sudo ln -s /usr/bin/ntfsfix /sbin/fsck.ntfs
sudo ln -s /usr/bin/ntfsfix /sbin/fsck.ntfs-3g
ntfsfix /dev/sda1

I was able to finally run a check unto /dev/sda1
Comment: Always copy exact error messages when asking questions, don't try telling about what you understood from them.
Answer: /dev/sda is the wrong device to run fsck on. sda is the whole disk. Your Linux filesystem  is on /dev/sda5.

superblock errors?


Origin of the idiom "butt of jokes"

Question: What is the origin of the phrase "butt of (all) jokes"? I'm wondering whether 'jokes' are being personified here (as per the origin of the term) with 'butt' being used as it's not exactly the most exalted part of the body, or whether 'butt' was intended more as a 'base' for all jokes? (I'm leaning towards the latter.)
Comment: I thought it might be related to the Dutch practice of Tonpraten where a person stands in a barrel (butt) placed on a stage and makes jokes and puns.
Answer: Butt 2. a.

A mark for archery practice; properly a mound or other erection on which the target is set up. Hence in mod. use a mound or embankment in front of which the targets are placed for artillery, musketry, or rifle practice.

Oxford English Dictionary
Comment: [Etymonline](http://www.etymonline.com/index.php?term=butt) confirms this is correct: "_target of a joke_, 1610s, originally _target for shooting practice_."
Comment: You can't ask for a better answer than that!
Answer: Did some sleuthing for print references. I found butt of the joke back to 1775, though up until the mid-1800s one was just as likely to be a butt of the jest. Prior to this reference, it seems one could be the figurative butt of various slings and arrows all the way back to the early 16oos, as Etymonline has it.
Here's the 1775 reference from Observations, Historical, Critical, and Medical, on the Wines of the Ancients, by Sir Edward Barry, explicating on the rank of ancient Roman slaves in relation to rank of guests:
Answer: Butts were, as is pointed out above, the archery targets erected permanently in or near a village or town for archery practice, required by law by Edward III in 1363 (also forbidding all sorts of other, more decadent pastimes such as football. See various archery reference books, including 'The Longbow' by Mike Loades, Osprey Publishing, 2013. A butt is therefore a target, so the butt of a joke is the target of a joke. The French word for 'target' or 'goal'(as in a purpose) is 'le but' (also la cible). probably from Old Nordic 'butr' - a log. Log ends were, and still are, used for target practice. The Normans would have used this term and introduced it to English. Probably. You can still find 'The Butts' or 'Butts Lane' or some such as addresses today.
Answer: Update: Colin's answer is more likely correct. See the comments there.

To butt something can mean to ram it or hit it with the back end of something:

He butted me with the rifle.

To get the butt end of a joke is to receive the blunt of the joke. In other words, you are the one being hit or attacked with the joke. This phrase is useful partly because the person getting the butt can still be included in the joking around — you can be making fun of yourself and still get the butt of the joke.
Similar phrases:

He is getting the brunt of the joke.
He is getting the raw end of the deal.
He got the business end of a sword.

Someone who continually gets the joke butts can be referred to as a butt monkey but that may be returning to using "butt" to mean your tushy.
Comment: As an addendum, I would also like to point out, that in the English language, 'butt' meaning something blunt derives from it's original meaning of a large barrel rather than the human posterior. Hence the infamous lane in the UK 'Butthole Lane' which made the news when take-away companies refused to deliver food there, thinking it was a joke, rather than named after a damaged vessel!
Comment: PS: TVTropes warning.
Comment: "Butt" meaning "rear-end of a person" derives from "butt" meaning "rear end of a weapon", not the other way round.

Origin of the idiom "butt of jokes"


How do you create a planet-specific cryptocurrency that will ignore longer block chains from other planets?

Question: I'm sure that cryptocurrencies will play a huge part of the economy across the solar system, when we have colonized many different planets, moons, and asteroids. But there are problems with using a single coin for the entire solar system. Let's just start with the example of a Mars colony. Long distances mean long delays in communication so it would take a very long time to get confirmations of Bitcoin transactions that originate on Mars. That could be problematic. Additionally, people on Mars could never hope to mine bitcoins because the average communications delay between Earth and Mars is 20 minutes one way, which is twice as long as the ten-minute blocks of Bitcoin. So I believe that a different coin would be best for each planet. But here's the crazy part. Even if Mars had its own coin (let's call it Marscoin), Earth would most likely have more computer processing power, so miners on Earth could download Marscoin's block chain and extend it faster than the miners on Mars. Then the miners on Mars would no longer be able to mine Marscoin. Then we would be back to the same problem of using Bitcoin on Mars. So, I think someone would have to create a coin that can somehow be planet-specific, so that longer block chains from other planets will always be rejected.
Comment: People on Mars could use a different mining algorithm.
Comment: I think that would lessen the risk of having another planet taking over, but I don't think that eliminates the risk.
Comment: Will this even be necessary in the future? I believe by the time we have terraformed and colonized Mars, Quantum Entanglement will be the primary method to instantaneously transmit data...
Comment: http://physics.stackexchange.com/a/78130
Comment: There are a few technical issues with your statements, however, using theoretical quantum links for data transfer will be instantaneous.
Answer: Simply limit the block target (i.e. 10 minutes) to the speed of light (300,000 km/s).
Unless there is some wormhole or other unknown to reduce this limit, Bitcoin is safe from honest mining from any planet outside of 180,000,000 kilometers away (300000km/s * 60 sec * 10 minutes) since any miner can't keep up with the blockchain and would get any block at about the time the next block comes out.
Someone with more advanced technology / more hashing power could create a 51% attack and submit it to disrupt the Bitcoin economy even outside of this radius.
Comment: That's probably the only way. Quite an ingenuous idea. But I don't know if a block time can be that short. Surly there's a reason all of them (afaik) being a few minutes or so.
Comment: The first attempt at drastically lowering the block time was GiestGeld, which had a block time of one or several seconds. This caused huge issues with massive blockchain forks and concurrency issues due to latency between nodes. It has been generally agreed that 60 seconds is the lowest reasonable time to target for generating a block, propagating to the network, and expecting most miners not to have found a block by then (if it takes 6 seconds to transmit a block to the whole network with a 60 sec target, 10% of blocks will be stale/rejected because they would be found during this time).
Comment: As you mentioned, a small block interval does not protect from another planets mining efforts if it has more mining power. I've given an explanatory example in another [answer](http://bitcoin.stackexchange.com/a/34310/5406).
Comment: 0 latency information streaming is already possible, by the use of electron pair parking. The only way I see is by physically limiting the mining computers, thus creating a central bank, but with the sole purpose of creating currency which may again be automatically distributed to physical (digital) producers (i.e. video, audio, 3d, rewarded by usage).
Answer: TL;DR: Whatever block interval one employs, another planet with greater mining power will eventually overtake the local blockchain. It would only be possible to lock other miners out by adding low-depth checkpoints.
Gedankenexperiment:
MarsCoin starts a new blockchain with a 2 minute block interval, they have one Unit of Mining Power [UMP] at their disposal with a new MarsCoin specific mining algorithm.
Some traders from Earth start using MarsCoin for their transactions with Mars colonists. They get blocks with a 20 minute delay (as proposed in the question). After a while they realize that the MarsCoin mining rewards are quite juicy and technology is much cheaper on Earth than in the underdeveloped colony: They create mining equipment with 2 UMP, allowing them to find blocks twice as fast than on Mars.

-20 minutes: Mars is at Block X and broadcasts it to Earth.
…
0 minutes: Earth receives Block X from Mars, and starts their own mining effort. The difficulty has not increased yet, so they can mine one block per minute for the time being. Mars is at Block X+10.
2 minutes: Earth receives Block X+1 from Mars, but Earth is already on Block X+2 on their own chain. Earth subsequently outperforms Mars and continues mining on their own chain. Mars is at Block X+11.
…
21 minutes: Mars receives the first block Block X+1 from Earth and discards it, because Mars found Block X+20 at 20 minutes. Earth is at Block X+21, and received Block X+10 last from Mars.
…
61 minutes: Mars receives Block X+41 from Earth, Mars is at Block X+40. Earth's chain's total proof of work is greater than Mars' chain's. Mars' chain is discarded in favor for Earth's. Mars' miners lose the mining reward of the last 40 blocks. Earth is at Block X+61.

Conclusion:
Neither distance, nor block interval are sufficiently prohibitive. As long as the other planet has more mining power it will eventually overtake the local blockchain.

Addendum: Short block interval with checkpoints at low depth
When I just read this question again, I thought of another thing. If one was hellbent to keep non-martian mining efforts from bearing fruits, one could introduce a sliding checkpoint scheme. In my above example, where I was prescribing a block interval of two minutes and terrestrian mining was twice as fast as martian mining, it would take a reorganization of more than forty blocks for the terrestrian chain to replace the martian.
If the community of Mars agreed upon forbidding chain reorganizations of more than 15 blocks (which at two minute intervals is less time than that of a radio wave roundtrip) by adding every block with 15 confirmations to the checkpoint list, terrestrian miners would be able to fork themselves from the Marscoin chain, but would never be able to take over the martian mining.
Answer: If hashes are cheap on Earth, you want them exported to
Mars to improve the security of the Martian block chain.  Exporting
hashes is easy to do in the stateless manner we expect from
decentralized Bitcoin technology.
Each block on a block chain is protected against modification by the
proof of work it shows and by the proof of work shown by the blocks
that follow it. This proof of work is communicable---the work done in
one chain can be applied to another chain.
So, for example, we have Marscoin and Bitcoin.  Bitcoin (still focused
on and near Earth) is by far the stronger chain.  Marscoin is great for
local transactions on Mars, but nobody trusts it for serious savings
because its network difficulty is much lower than Bitcoin.
However, some people on Earth start to include hashes of recent Marscoin
block headers in their transaction outputs (maybe using
ContractHashTool to
do this as a part of their regular transactions).
Following a soft fork of Marscoin, Marscoin full nodes download both the
Bitcoin block chain and the Marscoin block chain. Looking at the Bitcoin
block chain, they find the first Marscoin header hash encoded in an
output and look at how much proof of work is protecting that transaction
on the Bitcoin block chain. They add that proof of work to the
corresponding block on the Marscoin block chain---now that block is
protected by the combined hash rate of two planets! For example:

Bitcoin Block 10,000,000

Confirmed 100 times
Protected by proof of work equal to 10^72 hashes
Has a transaction that references Marscoin block 50,000

Marscoin Block 50,000

Confirmed 200 times
Protected by native proof of work equal to 10^48 hashes
External proof of work adds an extra 10^72 hashes

The Marscoin full nodes perform the same calculation for any other
Marscoin header hashes found in the Bitcoin block chain. Now attacking
all but the most recent Marscoin blocks requires attacking Bitcoin at
the same time.
To prevent denial-of-service attacks against recent blocks, methods like
Gavin Andresen's require-priority
idea
can ensure high-priority Martian transactions get through even if
malcontents try using cheap Terran hash rate in short-chain 51% attacks.
Now Terrans and Martians can live in peace and harmony---all thanks to
Bitcoin. :-)
Answer: This came from bubfranks on reddit:
"Oh fun! Let me try.
Given a random stream of bits that was impossible to predict, but agreed upon by local miners, reject blocks that do not include a valid bitstream. The probability of getting scooped by a cooperation between external hashpower and an internal node would be a function of the speed of light, distance between the attackers, and length of a valid bitstream."
Comment: I think this could be a good answer, but as it is presented right now, it is hard to understand and should be explained further.
Answer: why don't we just increase block confirmation time from 10 minutes to 1 day for specific interstellar fork. I think the whole day of unconfirmed transactions is okay for interstellar network & will expand the radius draasticaly.
Comment: That wouldn't stop another planet from taking over the chain with more mining power, leaving us with both drawbacks, the latency for confirmations and huge block intervals. So, there would be no benefit over just having to wait for 50 minutes to get the first confirmation on the Bitcoin blockchain.


Where was the Kodesh haKodoshim?

Question: I have always been under the impression that the mosque on the Har HaBayis is on the location of the Kosdesh HaKodoshim. Is that accurate?
Comment: I have never heard anyone say it was under the [only mosque on the mountain](http://en.wikipedia.org/wiki/Al_aqsa_mosque).
Answer: The Radva"z in responsum 691* confirms that without a doubt the אבן שתיה (and by extension, the inner sanctum) is located "under the dome". He also notes that figuring out the  particulars of what used to be where on the Har Habayis is very tricky business and requires careful calculation.
*Bonus - This may also be the year construction on the dome was completed.
Comment: Probably worth clarifying that this would mean that it was *not* where the mosque (Al Aqsa) is, but rather by the Dome of the Rock, which is not a mosque, since this is a common source of confusion (which is presumably what @DoubleAA is driving at in his comment on the question).
Answer: That said, there are modern researchers who think that it was either (a) the base of the Mizbeyach (Altar), or (b) outside of the Temple complex altogether - according to this view, the sanctified part of the Har Habayis (500x500 cubits, Middos 2:1) lay in the southern half of the present-day Temple Mount (and incidentally, according to this view, the Kodesh Hakodashim turns out to be pretty much directly behind the Kosel plaza).
This was discussed in Techumin sometime in the '90s, although I'll have to look up the exact reference.
Answer: Rav Moshe Sternbuch in his Shaalos U'Tshuvos writes that he is certain that the location of the mosque is not the exact location of the Kodshei HaKodoshim.
Comment: do you know which volume and which teshuva?

Where was the Kodesh haKodoshim?


Is there a good crash course website or book for auto repair for beginner who's just getting into auto repair?

Question: I'm wondering if there's a good crash course website or book for auto repair for beginner who's just getting into auto repair?
Comment: well, at risk of sounding facetious, this site can be very useful. As you come up against a problem, or an area you need information on, ask the question.
Answer: The best resource I've found, for someone mechanically inclined, is the specific Factory Service Manual for whatever car you are working on. They typically describe how to disassemble the entire car, step by step, with pictures.
If you're into a more basic "Why are cars designed this way?" type of discussion. Google, or the site: howstuffworks.com is also decent.
Comment: While I too would recommend FSM for any serious DIYer, I do not think it qualifies for "crash course" in auto repair. Procedures described there intended for professional mechanics with knowledge of proper techniques and tool use. OP would be better served with a general book for beginners (even the kind for dummies or idiots), that would explain those tools and techniques.
Answer: A combination of Auto Repair for Dummies, and the Haynes guide to my vehicle taught me a lot. The For Dummies book is written for complete beginners, but suffers from being very generic. The Haynes guide can fill in the void with information specific to your vehicle, without being overly complicated.
Comment: I agree. A Haynes manual for your particular is a good idea. The instructions and techniques will be more relevant to you. You can achieve some pretty extensive work following step by step guides.
Answer: As Nick said, if you can get the Factory Service Manual for your vehicle, that's probably the best. It can be expensive (like $200+) though unless you can find PDFs online. A much less complete, but still very helpful, book to get is the Haynes manual for your vehicle; you can pick it up at any decent auto parts store for something like $15-20. Also, YouTube is a great resource. If your vehicle is pretty common, search for the procedure you want to do and you may find a video of somebody doing it and explaining how. For less common vehicles, you still might be able to get some good ideas watching similar videos.
Answer: Youtube. Seriously. There's a video covering just about any procedure you can do to your car. E.g. here's a video explaining how a (Toyota) twincam engine works. About a year ago when I wanted to replace the turbo on my Astra Coupe, I found a video show every single step in the process.
If you want to get into auto repair as a complete novice, then start with the easy stuff like changing the oil, sparkplugs and coolant. Maybe swap out the coilpack, battery and air filter. Then you can move on to brakes and wheel bearings. First at the rear, then at the front. After that, you should have enough confidence to tackle the more serious things like installing fresh gaskets (stay away from the headgasket).
At this point you can probably start branching out into electronics, e.g. installing a new head unit, amp and speakers. Or figure out why the electric windows are/aren't working.
There's a video for all of this on youtube. Just search for "replacing X thing on Y model".


GPS constellation for Mars

Question: How would a constellation of GPS satellites differ for Mars? For Earth the system is supposed to work with at least 24 satellites orbiting at ~20.000 km. Would Martian equivalent need less of them? At what orbit height?
Comment: Good question! Other systems like [Glonass](https://en.wikipedia.org/wiki/GLONASS), and [Galileo](https://en.wikipedia.org/wiki/Galileo_(satellite_navigation)), and [BeiDou](https://en.wikipedia.org/wiki/BeiDou_Navigation_Satellite_System) have or will have a similar number of satellites in roughly speaking similar orbits to [GPS](https://en.wikipedia.org/wiki/Global_Positioning_System) ([groups in few planes of MEO](http://i.imgur.com/RxIQb4u.gif)). Earth atmosphere has a lot of water which varies the speed of the GPS signal. WIthout it maybe Mars would not need so many ground stations?
Answer: GPS requires four satellites being visible from any point on the surface at any time (one less if the receivers carry a high-precision atomic clock).
On a perfect spherical world this can (theoretically) be provided by eight satellites in a very high orbit - from far away every observer can see exactly half of the planet. This constellation would use four different orbits with two satellites positioned opposite to each other in each orbit.
High orbits might not be favorable due to the large distance to the receivers and accordingly high transmitting power needed and also larger measurement errors. Additionally, satellites that are barely visible above the horizon can be obstructed by mountains (do exist on Mars) or high buildings (don't exist on Mars yet). So, one might want to place 3 satellites in each orbit and use more than four different orbits.
A GPS that is available at any time at any point of the surface and that guarantees a minimum elevation (10 degrees according to my very rough estimate) above the horizon can likely be built with about 15 satellites (e.g. 5 orbits with 3 satellites each).
The 24 satellites used for the Earth-GPS are due to lower orbits, high minimum elevation (atmosphere is thick at low elevation angles causing large errors) and redundancy. Note that four satellites visible is the absolute minimum to do any position estimation. A fifth one is already needed to make any estimation on precision.
For Mars I'd assume one is fine with a lower precision than on Earth and one does not want to spend too many satellites and hence goes with a lower count of satellites in higher orbits. 15 seem likely to me.
Also note that in no calculation the size of the planet plays a role - it's only the ration between planetary radius and orbital radius that determines the area a satellite can be seen from.
Comment: About the planet size - I am imagining that to get the same error-rate you can you se the same absolute height (or even higher because of smaller effects of the thinner atmosphere) so the ratio can be different?
Comment: There is not too much difference here: The earth atmosphere causes quite some errors, but these can only be corrected by measuring the properties of the atmosphere (e.g. by stations at defined positions), height of satellites doesn't help, only elevation above the horizon (which means less atmosphere in between) plays a role. From this point of view, satellites close to the horizon can be used more reliably on Mars than on Earth.
Comment: Doesn't the planet size affect what would be considered a "high orbit"?  I imagine there's a threshold where it's cheaper to use more satellites than to use a stronger signal, and that would depend on absolute distances rather than the ratio.  GPS on Earth is about 26Mm, much less than the >70Mm radius of Jupiter; would the same ratio be just as good there?
Answer: From the 3rd Kepler's law you can find that the orbit radius for the satellite in a circle orbit can be found as
$$
R = \frac{G^{1/3}}{(2\pi)^{2/3}} T^{2/3} M_{planet}^{1/3}
$$
So if you take $G=6.67 \times 10^{-11}$ SI units, $M = 6.4171\times 10^{23}$ kg, and, like GPS satellites, $T$ is equal to half of the Martian sidereal day (which is 24h 37m 22s or 86644 seconds), you finally get
$$
R = 12672~\text{km}
$$
from the center of the planet.
It also means that the orbit should be about $9282~\text{km}$ above the average surface of Mars. In case of Earth, such an orbit is more than twice as far out since Earth is more massive.
The number of satellites may depend on actual configuration and requirements for the minimum number of satellites visible from a certain point of surface (if you need 24/7 performance), but it can't be much less than the same in case of Earth. I believe something about 18 (6 in three orbital planes) is a necessary minimum.
Comment: Where do you see the necessity to have an orbital period of half a day?

GPS constellation for Mars


reverse engineering methodology

Question: I'm new to reverse engineering and I'm following the on line course provided by the opensecurity.info site.
The author provides a methodology for reverse engineering. He recommends to find a function of interest and pseudo code it.
From the wording used,  it sounds like I should reverse the whole function from the its start to its end.
Is this really the recommended practice?
If my question isn't clear enough, here an hypothetical case:
Let's say I want to understand the communication protocol used to exchange data between a malware and the command and control server. Let's say I found the recv call and this call is in the middle of an unknown function. Should I really reverse this unknown function from its start or should I focus on the area of the code inside this function that calls "recv" and go from there?
Answer:
Should I really reverse this unknown function from its start

Disclaimer: This is just my opinion. That said, my answer: no, don't do that unless you really need to do that. One of the first things I always say to my students when I teach reverse engineering is actually that: never try to reverse engineer a function line-by-line unless you really need to do so (and my experience says that most of the time you don't need to do so).
My recommendation is a bit different:

Find "artifacts" than can give you an abstract idea about what a function does: called/referenced function names (i.e., APIs), constants, etc...
After you have an abstract idea of what the function does, determine if you need to get more information from it.
If so, try to determine grouping basic blocks but without analysing line-by-line, what a set of basic blocks do, trying to focus on what you do not understand or what you need to answer.
If you still need more details or something is still unclear, do it basic block per basic block following the flow from the point that is not clear or from the point that you start to care.
If, still, you need more information or it's still unclear, do it instruction by instruction trying to focus specifically on what you do not understand or what you need to answer and, only if still you cannot answer your questions, resort to reverse the whole function line-by-line.

Trying to go instruction by instruction or reversing the whole function when we really don't need to do so, it's easier to get lost/confused because we will be focusing on what some obscure instruction does or which flags it changes instead of focusing in answering the real questions. However, it will largely depend on why are you reverse engineering that thing. Are you trying to mimic/copy/extend an algorithm (i.e., a decryption algorithm) or recovering the source code for a binary? Then, yes, you will need to go instruction by instruction. Are you reverse engineering a piece of software/function in order to determine what it does? In general, no, you don't need to go instruction by instruction.
My 2 cents.
Comment: There is no "methodology", there are only imaginary constructs written up by random people. If there were a software engineering methodology, you'd just apply that one in reverse :D There are good practices, though, and what Joxean describes is one of them.
Answer: I suggest you took a look at the rest code, too. Finding something in specific can definitely be a breakthrough, but one line of code - especially in assembly - can't do a lot on its own. Look at the example you gave. You found how your malware communicates. Is that enough? Probably not. What is the nature of this communication? Is it a reverse shell? Is it used to transfer files? There are many different questions to be answered and - trust me - you will be very lucky if you can find them all at the same point of the code. Always look at the code around the area of interest you have. You might find functions that call other functions that do interesting stuff using the communication channel. One thing brings the other and at the end of the day, it will bring you the full structure and functionality of the malware.
P.S. Always use breakpoints when going from function to function.
Happy hunting!

reverse engineering methodology


Role of Calcium and Magnesium in capacitation/acrosome reaction

Question: During the acrosome reaction, the activation enzyme present in the sperm dissolves the corona radiata and zona pellucida enabling the sperm to reach the plasma membrane of the egg.
Also calcium and magnesium ions play an important role in acrosome reaction [ref].
What I fail to understand is how exactly do calcium and magnesium ions play a key role in acrosome reaction?
Answer: The process is not clearly understood. Calcium helps in capacitation: During capacitation calcium enters the spermatozoa through ion channels; blocking these channels inhibits the acrosome reaction but what calcium does inside the spermatozoa is not very clear. This paper says that calcium activates a certain tyrosine kinase in the spermatozoa which in turn activates a protein called p32. This they say occurs "concomitantly with capacitation". Other papers cited by this article talk about involvement of calcium dependent adenylate cyclase.
This article also says that protein tyrosine phosphorylations are important for capacitation but doesn't describe how.
I could not find a more precise information on this topic. I shall update the answer if I find one.


How do I complete the Invitation image?

Question: In the gallery menu there's an Invitation image that is filled as I play. How do I complete it? Are there events that unlock each part or is it just the more I play the more it gets discovered?
Answer: If you're playing on XBox 360, the invitation image unlocks as you get the achievements.

How do I complete the Invitation image?


Rooting already unlock phone without losing data, possible?

Question: As far as I have understood it's the unlocking part that requires wiping, and the rooting part doesn't. So, if I am already unlocked, can I root without losing my data? I've got a (red) Nexus 5 16GB Unlocked running Android 5.1.
Answer: Yes, you can root as many times you want without losing data if your device is unlocked. I've done that on my OnePlus One.
For further clarification, it's the default mechanism in the device set by the OEM, that whenever the bootloader's default (locked) state is tampered it would issue a data wipe (a Factory Reset), most probably to protect the user's data from a possible compromise.
Rooting on the other hand is moving a binary (su) under system (usually at /system/xbin and placing symlinks at locations like /system/bin) which with proper files permissions can be executed by an ordinary user  to gain supreme rights on the system.
It is possible that the rooting method you attempt in your device isn't the standard (via Recovery) one but needs a one-click tool, and some users have reported data loss with the latter, so you may take a backup to be on the safe-side.
Further reading:

Bootloader States
Why does unlocking the bootloader wipe phone?
What does to a "to root a phone" mean?
How does rooting work?
Comment: Do you know any methods that do work, since you mentioned you've done it? Like CF AutoRoot for example, since that's the one I've been using for rooting. Thanks.
Comment: I've a custom Recovery (TWRP) running in my phone, so rooting is easy. I just download SuperSu.zip and flash it via recovery, done! No data loss, nothing. I've seen many threads where same approach is used on Nexus phones as well.  I don't think rooting instructions for Nexus 5 will vary but take a look at [Nexus 7](http://android.stackexchange.com/a/37761/96277) which does the same thing  I mentioned here.
Comment: Thanks, man. [Random nonsense to get up to the 15 characters limit]
Answer: In most of the cases, rooting won't cause data loss unless it failed. The challenging part is how to unlock the bootloader if there was. For unlocked phone, you can easily get the phone rooted with apps such as AnyRooter or TWRP.
Comment: Welcome to our community. It's great that you're posting answers to help others. Since this question already had an accepted answer, which made the same points you've raised, you probably won't get much attention for this answer. If you want to help where it's most needed, you can start with some unanswered questions (link in the top-right), and people will be grateful.


Change of domain name

Question: I have a the following case. A client of mine had a domain name (registered to his company), but anyways the domain was arbitrated by another company that won it.
The problem is that now we can't start a proper change of domain names with 301 redirects (because the domain is already redirected to the other company website) and the question is what's the best solution of this problem without losing too much traffic and rankings?
Comment: See this more recent related question addressing using Google Webmaster Tools as an option to move sites: http://webmasters.stackexchange.com/questions/81810/preserving-search-engine-rankings-when-old-domain-name-is-lost
Answer: You essentially have already lost all of your traffic and rank. You are in effect, starting over. There is nothing you can do about it short of buying back the domain and I rather suspect that is unlikely.
Just deploy the website on your new domain and begin building back-links again. Create new PR where you had used PR sites in the past, and update any social media that you can. In your case, you will have to scramble twice as fast to out-pace the damage of losing the domain name versus starting a new site. But it can be done. But please expect that it will take as long to get back to where you were as it took to get there in the first place. It will not be easy or fast.
Answer: You have losted domain so all traffic and ranking will never came from your domain,You need to start from scartch.
Mine advice : Try to put old site to new domain that give some ranking (if your content is worth)

Change of domain name


Are there parallels for when Jesus wrote with his finger on the ground?

Question: In John 8:6-8 says that Jesus wrote on the ground. I'm interested is there some parallel in Bible with that act? What does it signifies? Is it something like prophetic act, or some ancient Jewish "modus operandi" in some special cases?
Answer: In the ancient world papyrus was a valuable and expensive commodity. For ephemeral scribblings people used erasable wax tablets, or they wrote on the ground with a stick or a finger. There is the famous story of how the great mathematician Archimedes was drawing geometric figures in the dust when he was murdered by an invading Roman soldier. This was around 212 BC. By the time when the Christian gospels were redacted this must have become a proverbial example of a wise man ignoring the crises of everyday life and concentrating on his intellectual or spiritual work.
The sources are collected here: http://www.math.nyu.edu/~crorres/Archimedes/Death/Histories.html
Comment: Related to the Bible, how does Archimedes came up in the Bible
Comment: How does it relate to question?
Comment: @talmudist. The question was: "Are there parallels...."
Comment: Loads of ancients wrote on the ground...
Answer: this article explained everything what I wanted to know: https://www.academia.edu/991221/_Earth_Accuses_Earth_Tracing_Jesus_Writing_on_the_Ground_
summa sumarum: DIVINE FINGER - writer says that Jesus wrote with His finger.Here the author of the passage may be recalling Exodus 31:18, a verse that describes God inscribing covenant provisions with the divine finger. The writing on the wall in Daniel (5:5,24-28) also serves as possible inter-text Here divinely-sent fingers write letters announcing judgement...
NAMES IN THE GROUND-NAMES IN THE HEAVEN
-according to Ambrose Jesus wrote "earth, earth, write these men have been disowned",a passage that references Jeremiah 22:29-30 and 17:13 - Ambrose continues "their names are written in the ground".by contrast "the names of Christians are written in heaven"
- Augustine took the lead from Ambrose..suggested that Jesus writings shows that "those who abandon Him are written in the earth" (suported on Jer 17:13)
-traditions linking condemnation with divine writing, particularly writing in the earth, are much older than what is found among the Latin fathers
-in the second century Clement of Alexandria recalled Jeremiah 22 to argue that God writes the faithless into the earth and the faithful into heaven. "For the one in a state of ignorance, who is sinful, is also earth and ashes..."
This reminds me on theology of st. Paul in 1 Corinthians 15:46-48 ("So also it is written, "The first man, Adam, BECAME A LIVING SOUL." The last Adam became a life-giving spirit. The first man is from the earth, earthy; the second man is from heaven, As is the earthy, so also are those who are earthy...") In John 8 (wider context) Jesus is actually in fight with their stone-hearts who are under the written law, not under the Law of Mercy and Forgiveness, they do not want to receive Jesus, "a living soul", so they condamned themselves. ("Therefore I say to you, any sin and blasphemy shall be forgiven people, but blasphemy against the Spirit shall not be forgiven." Matthew 12,31. Here blasphemy stands for not willing to change your stone-heart, not willing to recieve Holy Spirit: love and mercy) Also, John 8 it's all about Jesus who is from heaven, and them, earthly people, ignorant about Heaven, the source of all Mercy (John 8,22.214.171.124.47.55) Earth and Heaven, uncompassion and compassion, hate and love.
THE MEASURE THAT YOUR MEASURE YOU WILL BE MEASURED Matt 7:2
-If you seek what is on earth, you do not seek what is in heaven - says Origen. So earth is their measure and Jesus is pointing that with His finger on the ground.
DANIEL 13
- the story of Daniel and the story of the adulteress were read in tandem on the third Saturday of Lent. If you read the story of Daniel you must notice that Susanna is victim ALONE..
TERRA TERRAM ACCUSAT-ninth century glossa, Codex Sangallensis 292, indicates that Jesus wrote "terra terram accusat", that is "eart accuses earth", meaning: a human judging a human, a mortal judging a mortal, a sinner judging a sinner". all of it makes sense in larger context, and it perfectly fits in the main message of Gospel.
Answer: No one knows what Jesus wrote with His finger but since everyone left - beginning with the eldest - some have conjectured that he just may have been writing names and places and circumstances that some of the present were involved with that were sinful.  Did He not say 'he who is without sin cast the first stone"?  Nothing like being reminded that we are all sinners to stamp out condemnation, huh?
Answer: It's a good question.  Any answer is going to be speculative.  The bible just doesn't provide detail.
That said many scholars have noted that whatever Jesus wrote in the ground had something to do with them being convicted and going away one by one, beginning at the eldest, even unto the last.

[John 8:9] - And they which heard it, being convicted by their own conscience, went out one by one, beginning at the eldest, even unto the last: and Jesus was left alone, and the woman standing in the midst.

Questions this raises include: What did Jesus write?  Was the woman a prostitute?  What convicted the men (eldest to youngest)? Had the elder ones been with the women?  How did they know she committed adultery?
We cannot know, and speculation abounds - but certainly something to think on.
Answer: John 8:6-8 form part of a passage known as the Pericope Adulterae, regarded as inauthentic by the great majority of biblical scholars, being absent from most early manuscripts, as well as being found in different locations when it does occur. The first manuscript of John to include this story is Codex Bezae, which dates to the fifth century, and on internal grounds these verses interrupt the narrative of John's Gospel and feature non-Johannine vocabulary and grammar.
Kyle R. Hughes ('The Lukan Special Material and the Tradition
History of the Pericope Adulterae') cites a landmark article published in 1988 by Bart Ehrman, which identifies the Pericope Adulterae as a conflation of two earlier accounts about Jesus showing mercy to a sinful woman. Ehrman says:

By the fourth century there were actually three extant versions of the PA:

the entrapment story in which Jesus freely pardons a sinful
  woman, known to Papias and the author of the Didascalia
the story of Jesus' intervention in an execution proceeding,
  preserved in the Gospel according to the Hebrews and retold by
  Didymus in his Ecclesiastes commentary, and
the popular version found in MSS of the Gospel of John, a
  version which represents a conflation of the two earlier stories.

Our earliest manuscript record of the passage in its present form, goes back only as far as the fifth century, although it may have existed for some time before this. According to Ehrman, it is a conflation of two earlier stories that are no earlier than the second century. We therefore can not reasonably attribute the present passage or either of its two predecessors to Jesus himself. There is no reason to think of this as either prophetic act or some ancient Jewish "modus operandi".
Comment: What you say about the pericope is correct, but it does not address the question of why Jesus is described as writing on the ground. The question is not about whether the "historical" Jesus wrote on the ground or not, but about the motivic logic of the narrative, be it fictitious or not.
Comment: @fdb I was not concerned with the historicity of the account, but whether it was either a prophetic act or some ancient Jewish modus operandi - as asked in the question. If indeed the pericope comes from a later Christian source, it is not an ancient Jewish modus operandi, nor prophetic. That outcome was the sole purpose of my analysis.
Comment: how can your conclusion ("there is no reason...") be based on facts about time of pericope production?
Comment: @Orhidea Thank you for your question. There could be reason to suppose this was a prophetic act if we are sufficiently sure that Jesus really did do these things, and there could be reason to suppose it could be some ancient Jewish "modus operandi" if it had been written in a Jewish milieu. Because it was written late, we can not be sure that Jesus really did the things described and we can be sure that the writer had no knowledge of any ancient Jewish modus operandi.  There of course remains a remote possibility, but no reason to think either of these explains the passage.
Comment: With respect to many early writers thinking it inauthentic, to be clear the vast majority of manuscripts fall into 2 camps: sourced from Asia Minor or Alexandria Egypt.  There are textual markers that suggest a texts origins and there was natural distrust between the camps.  The earliest copies of the pericope have all the hallmarks of an Alexandrian origin and no evidence exits there were copies in Asia Minor.  Accordingly it is NOT true there is evidence early Christians thought it inauthentic.  Certainly Alexandrian Christians didn't think so.
Comment: Rather when copies made their way to Asia Minor from Egypt doubts arose.  But then, early Christians in Asia Minor doubted any manuscript hailing from some place other than Asia Minor.
Answer: The sand, although minuscule, is a stone and from heaven that stone could be seen as a stone that lands (perhaps crushing a statue made of 4 metals) that ends one period of the world like the time when larger ancient creatures roamed the earth. The woman, not condemned, could be seen as blessed AMONG WOMEN and thus allows women instead of men to be available for the immaculate conception of Christ when the next age arrives.
Comment: Welcome to BHSE! Please make sure you take our Tour. (See below left) Thanks.


How was Shmuel permitted to kill Agag?

Question: How was Shmuel Hanavi, who was a nazir (Nazir 66a, Rambam Nezirus 3:16) allowed to kill Agag if in doing so he became tamei l'mais? I am looking for answers other than Shmuel using a wooden sword or him only terminally wounding (but not outright killing) Agag.
Comment: According to some mefarshim (yerai'im...) Gentiles aren't metamai at all. In that case the question wouldn't start.
Comment: "I am looking for answers **other** than...": why?? This is an episode that actually occurred, not a thought experiment. If he actually used a wooden sword, why won't you accept that answer?
Comment: @sabbahillel Actually, the verse suggests that he could have used an ax.
Comment: @msh210 The pasuk seem to say that he used a regular sword.
Comment: if downvoters could explain the problem with the question I would be happy to improve it.
Comment: @msh210 good question. I happen to not like that answer because it says that he cut agag into four pieces. I find it hard to believe that could be done with a wooden implement.
Answer: Rabbi Yechezkel ben Yehuda Landau (known as the Noda Beyehuda) in his work Doresh Letziyon, Derush 5 (new print p.46-47) poses this question. He takes the view that Shmuel Hanavi was allowed to kill Agag because of the principle of 'Aseh docheh lo saaseh'. The mitzva to kill Amalek (particularly, as he was the last living Amalekite at the time,) superseded the aveira of becoming tamei. This is quite a novel answer. The Noda Beyehuda understands from Shmuel's actions that this principle applies even when it would be possible to fulfill both mitzvos. Shmuel could have had someone else kill Agag who had no transgression to become tamei, or as he suggests, Shmuel could have killed Agag by shooting arrows at him. The fact that he personally killed him by cleaving him into four pieces, (ND"B citing Rashi) means that the mitzva overrode the issue of tuma.
Comment: How does one cut someone into four pieces in a single act?  If instead he cut in half, and cut the halves in half, isn't the latter action unneccesary to the killing, and thus problematic from a tumah angle?
Answer: Rabbi Reisman in one of his shiurim said that Shmuel could have worn gloves in order to prevent tumas mes. I found the reference when I sent the answer to MailJewish:

From: Hillel (Sabba) Markowitz <hsabbam@...>
  Date: Fri, 30 Jan 2004 12:44:56 -0500
  Subject: RE: Thank G-d for Tupperware

From: Andy Goldfinger <Andy.Goldfinger@...>
    That is where Tupperware comes in.  It is made of plastic, and to the
    best of my understanding, plastic is not mekabel tumah (capable of
    becoming impure).  Tupperware, and other plastic implements and utensils
    will make our lives much easier.
Might Tupperware be a good stock to buy as investment?

Rabbi Reisman in on of his recent tapes brought up the fact that
  gloves will be needed.  He pointed out that when Shmuel killed Agag,
  or when Pinchas killed Zimri and Kozbi, they could have required
  gloves so as not to become tamei.  IIRC they would have needed two
  pairs of gloves so that the tum'ah does not cause the gloves (which
  are now tamei) to make the person tamei.  I think that is because the
  level of tumah for a sword is higher than a regular object that
  touches a dead body.
The comment about plastic means that a person can wear plastic
  disposable gloves and not become tamei at all.  Just pull out the
  gloves and put them on before touching anything tamei.
Sounds like a good investment.
Hillel (Sabba) Markowitz - <sabbahillel@...>
Answer: Whether Shmuel was a nazir is a matter of dispute on Nazir 66a. Rabbi Nehorai says he was while Rabbi Yossi says he was not.
The derivation of Shmuel's nezirut is from Shimshon. Thus:
שנא' (שמואל א א, יא) ומורה לא יעלה על ראשו נאמר בשמשון (שופטים יג, ה) ומורה ונאמר בשמואל ומורה מה מורה האמורה בשמשון נזיר אף מורה האמורה בשמואל נזיר
If so, perhaps the extent of Shmuel's nezirus was the same as that of Shimshon, which did not include ritual impurity. As the Rambam writes about Shimshon's status:
יג  שִׁמְשׁוֹן לֹא הָיָה נָזִיר גָּמוּר--שֶׁהֲרֵי לֹא נָדַר בְּנָזִיר, אֵלָא הַמַּלְאָךְ הִפְרִישׁוֹ מִן הַטֻּמְאָה; וְכֵיצַד הָיָה דִּינוֹ--הָיָה אָסוּר בְּיַיִן וְאָסוּר בְּתַגְלָחַת, וּמֻתָּר הָיָה לְהִטַּמֵּא לַמֵּתִים.  וְדָבָר זֶה, הֲלָכָה מִפִּי הַקַּבָּלָה.
יד  לְפִיכָּךְ מִי שֶׁאָמַר הֲרֵינִי נָזִיר כְּשִׁמְשׁוֹן--הֲרֵי זֶה נָזִיר מִן הַיַּיִן וּמִן הַתַּגְלָחַת לְעוֹלָם, וְאֵינוּ מְגַלֵּחַ כָּל שְׁנֵים עָשָׂר חֹדֶשׁ כִּשְׁאָר נְזִירֵי עוֹלָם, וּמֻתָּר לְהִטַּמֵּא לַמֵּתִים.  וְאִם אָמַר לֹא נִתְכַּוַּנְתִּי אֵלָא לְאִישׁ אַחֵר שֶׁשְּׁמוֹ שִׁמְשׁוֹן, אֵינוּ נָזִיר.  וּמִי שֶׁנָּדַר נָזִיר כְּשִׁמְשׁוֹן--אֵינוּ יָכוֹל לְהִשָּׁאֵל עַל נִדְרוֹ, שֶׁנְּזִירוּת שִׁמְשׁוֹן לְעוֹלָם הָיְתָה.
Admittedly, the Rambam there explicitly distinguishes the nezirus of Shimshon from that of Shmuel, but perhaps one might argue.
Comment: All this does is change the question into: According to those who say _Shemu'el ha-Navi_ was a _Nazir Olam_, how was he allowed to kill Agag if in doing so he became tamei l'mais?

How was Shmuel permitted to kill Agag?


How do I store voicemail password on WP8?

Question: I would like to store my voicemail password on Windows Phone 8. Is this possible?
Comment: You mean for Visual Voicemail? If it isn't storing it you need to call ATT
Comment: This is on Verizon Wireless. Just plain voicemail.
Comment: I don't think it is possible
Comment: Seems like on Android I was able to put in a contact that included voicemail number and password.
Comment: You might be able to do something like that, have it dial your voicemail, insert some pauses, then dial in the password. I've done stuff like this for speed dial on different systems before.
Answer: In theory you should be able to save your VM pin in the Dialer settings. There is an option to turn OFF the default voicemail number and enter in your own. (For Verizon you would enter *86,0000# where 0000 is your pin, the comma can be accessed by pressing and holding down the "." key)
This worked on my WP7 phone (HTC Trophy) and I've tried several times on my HTC Windows 8X but continue to recieve an error message ("We're having trouble saving your voicemail number right now. Please try again later").  Don't know if it's a Verizon, Microsoft or HTC issue and have been unable to find anything about it on the web.
UPDATE
This appears to be a permanent limitation/feature of WP8. According to a Microsoft MVP, overriding the VoiceMail number to include your PIN is a security issue.

The system doesn't let you intentionally override security for
  voicemail. You can do this for numbers stored in your normal contact
  list, but you can't concatenate your password to the voicemail number.
Answer: YESSS!!!  IT IS POSSIBLE.  here is my simple cheat for the voicemail p/w dilemma on my WP8... Without creating a contact in your phone book.  The commas wouldn't save for me after trying the above. So I used a lower case letter p.  AND yes I know WP8 limits the input in the phone settings area SO- The trick is to  type it into a text anywhere else-
For example -
*86pp1234567 (you can use either one or two p's)
Then highlight and copy it.
Then go back to the settings and paste it in place of the default voicemail #.
Comment: Awesome work-around.  Works perfectly for me.  This should be the accepted answer.
Comment: Yes ... it absolutely does.
Nokia Icon (Lumia 929).
Created the *86pnnnn in a text message window, copied to clipboard, then pasted into the non-default text box in the Voice Mail Settings.
Then called VoiceMail and password was entered!
Excellent!
I had previously created Voice Mail contact - which also works.
Answer: I had same problem with error message when trying to change the standard VM number.  I created a new contact called "Auto Voicemail" with the *86,0000# and use that if I need to be hands free.
Answer: You would first need to know your Voicemail number. You can go to the website of your carrier, or simply call.
Then, you would need to use the copy/paste method used on Cellenbow's answer.
Type the number in a normal text box, then highlight and copy, go to the Voicemail input box. And paste.
You would need to use either , (comma) or p (pause). Comma can be accessible from the . (Dot) key in the Voicemail, hold on the dot key, then you can choose the comma.
You might need one or two commas or pauses. It depends on how your voicemail carrier settings. I would recommend calling voicemail, and having a stopwatch or anything similar, and count how many seconds are there from the time your call get answered, untill they require you for PIN entry. And every comma/pause is worth 3-5. So you might need to count for that. But don't use too many, because then your call will be dropped for timeout.
Also, some carriers will require you to enter your PIN then press the # (pound) key. If that is the case, then you will need to include that.
Think of it as if you are telling the phone what to enter in the keypad when u call someone, they created this method so you can store phone numbers with extensions to be autodialed.
Finally, WP8.1 might be just fine with entering the comma and the PIN right away, and it will save it without any issues. (I have tested it)
I know this question was asked a long while ago, but I hope this was helpful and brief. (It is self-explanatory)


Is WebKit gaining any traction in non-web applications?

Question: I spoke to the boss of a major music software company a few years ago. He told me that if they were going to start again from the ground up, they might look at WebKit for their UI. This totally surprised me. But I'm wondering if other folks are thinking and acting this way. Is webkit working its way in to truly non-web software?
Answer: RealPlayer, iTunes, and many other applications are using it, so are some non-"web" apps such as desktop widget programs:
http://trac.webkit.org/wiki/Applications%20using%20WebKit
Designing "web-apps" with HTML/Webkit UI is beneficial for Mobile users, since many devices have Webkit built in. Even if it is currently only used on a PC, you would have the possibility of hosting it on the web or local network later, with less work to convert it.
Answer: Gwibber, a Gnome twitter client that ships with Ubuntu, uses WebKit for displaying timelines (although it uses normal GTK+ widgets for the surrounding UI).
I would consider WebKit a viable option for many pieces of UI, particularly if the program shell exposes appropriate hooks into the surrounding platform to do things like launch a real browser or hook in to system notifications.  You run the serious risk, however, of building an application that doesn't fit well in the UI conventions of the user's operating system.
It's not WebKit, but building a UI on a rendering engine is essentially what Mozilla does - Firefox, Thunderbird, etc. are built in XUL rendered with Gecko.
Answer: Anything you can do on webkit can be wrapped as an application easily with PhoneGap or other tools.
For example, store.sonyentertainmentnetwork.com could be wrapped as an OSX app, an Android app, and still act as a regular website very easily.
Also: https://products.sel.sony.com/opensource/source_webkit.shtml


What is this light purple flowering ground cover?

Question: The small flowers look pretty, although the green foliage's somewhat wild - could this be a weed?
Comment: Wild geranium, these plants are sold at nurseries for the same price zonal geraniums are sold.  Stinky.  I think they are a bit stinky.  Lots of 'indigenous' flora is considered weeds, cause they are well adapted to the area.
Comment: Thanks for your response. There is hardly any smell. With my eyes closed, it smells just like a growing plant, definitely not stinky. I'm thinking it's not geranium but something else perhaps?
Comment: Sure looks like wild geranium to me...did you squeeze a leaf, stem, run your hands through it?  My horses eat this and I smell it on their breath and poo.  Trust me, they managed to nab some on a ride wouldn't feed it to them on purpose, grins.  If it doesn't smell I think we should keep looking?
Comment: When un-touched, there's hardly any smell at all.. I squeezed, rubbed and tore some leaves and stem - not much smell still.. Yet everyone seems to think it's geranium - maybe here in my London garden a new non-smelling variety developed? :) .. Let's keep looking, thank you and good luck with your horses they must like the taste
Comment: Ugh.  My horses skin smelled like wild geranium.  There are lots of people that differ in olfactory standards, grins!  You might be immune or inured to this smell.  I think it is wild geranium.  Bamboo lives in London. I think I'll go ping her!
Answer: It looks to me like Herb Robert, a wild geranium with a particularly sharp smell. Personally I don't like the smell and I pull it out on sight.  It's very easy to pull out.
Comment: @15UK The seed pods certainly look like a geranium, aka cranesbill, to me.  And the stem looks hairy and sticky as well, another common feature.  I've been looking at photos via Google and the leaves are slightly different than in your photo.  I wonder if that, and the scent, could be local variations.
Comment: Thanks for your response. There is hardly any smell. With my eyes closed, it smells just like a growing plant, definitely not a sharp smell. I'm thinking it's not geranium but something else perhaps?.. Very easy to pull out indeed.
Comment: Thanks. I've googled it too, found some similar looking plants but not exactly. Quite a number of people seem to think it's geranium - maybe here in my London garden a new non-smelling variety developed? :)
Answer: Looks like Herb-robert (Geranium robertianum) to me. If I'm right, it's a North American wildflower. Which doesn't mean that it won't act like a weed in your garden. Most geraniums are groundcovers and spread pretty well once they're established, so this one could take over a garden bed.
Comment: Also a wildflower in Europe and Asia.
Comment: Thanks for your response. The plant does indeed spread pretty well in my garden (London, UK)
Answer:   Geranium maculatum
And there are zillions of different 'flavors', slightly different leaves, different colors of flowers from bright white, to vivid blue, pale purples, pinks.  I'd leave them if you were me.  The bees LOVE these plants. Depends on your landscape goals, not mine.  I have a hard time finding plants to grow here much less with profuse flowers.  All plants flower some are just more profuse and visible than others.  I wonder what the honey tastes like if bees were visiting wild geranium?  That is how strong this plant smells.  But you have to crush or disturb this plant to get a hit!
I think if you pulled off some flowers and pulled off some dead flowers which will make them bloom even better at the same time reducing how much seed the plants set...you HAVE to be able smell sharp/musky/not my favorite smell at all.
I had a Johnson' Blue Geranium which is a hybrid of this wild one.  Flowers PROFUSELY from spring through fall.  I got kinda OCD and daily went out to snip old flower capsules, to keep it profusely flowering and boy did it!  The bees were in heaven.


How long will it take for Starman to get to Mars?

Question: How long will it take for the Starman to get to Mars? I'm following the incredible launch of the Heavy Falcon and Starman, and would like to know. Thanks!
Comment: I don't think SpaceX has said for sure, but some observers are speculating that there will be a Mars flyby in October of this year. Because the upper stage of Falcon Heavy isn't able to operate for very long, it won't be able to make the midcourse corrections needed to precisely target Mars, so the flyby may not be very close at all. https://www.youtube.com/watch?v=md0K_eRSHAE&feature=youtu.be
Comment: I thought the answer was: never. Achieved a solar orbit with aphelion beyond the Orbit of Mars, perihelion close to Earth orbit, so Mars crossing, not necessarily Mars approaching.
Answer: Don't know how specific you want, but at 7:59 AM - 6 Feb 2018 Elon tweeted

About 2.5 hours to T-0 for Falcon Heavy. Watch sim for highlight reel of what we hope happens. Car actually takes 6 months to cover 200M+ miles to Mars

Edit: A clarifying note that we just learned as well.  Again according to Elon on 7 Feb. 2018:

Third burn successful. Exceeded Mars orbit and kept going to the Asteroid Belt. Image of expected orbit
Answer: It won't ever really get to Mars, but it will be pretty close in 2020, and even closer in 2035. I did a video linked below that shows this.


Dual Canadian / Irish Citizen moving to the UK

Question: So I am a born Canadian citizen but also Irish and I hold both passports. I'm moving to the UK and I'm confused about entry at immigration. I know I have to leave Canada using my Canadian passport but can I enter using my Irish passport through the EU line? I'm getting conflicting info, as some info I have seen suggests that if I try to enter on a different passport there may be conflict with immigration because my Canadian will be in their manifest.
Comment: Possible duplicate of https://travel.stackexchange.com/questions/52100/i-have-two-passports-nationalities-how-do-i-use-them-when-i-travel
Comment: It doesn't matter if your Canadian passport is in their manifest, but anyway you can use your Irish passport to check in with the airline, and then that passport will be in the manifest.
Answer:
can I enter using my Irish passport through the EU line?

As an Irish citizen you have an absolute right to enter the UK, in fact more so than other EU citizens. So they cannot refuse you, full stop, regardless of what the passenger manifest looks like.
In any case, you should check in using the Irish passport (although in the case of Canada, airline staff may want your Canadian passport as well, since Canada does not do exit border checks). As a rule of thumb, you should use the passport to be used for the destination country.
Comment: @Ulkoma Old British-Irish treaties. In fact, before 1949 Irish people were even British subjects. Whenever an Irish Person enters the UK, they get permanent resident Status, while other EU:ers have to wait for 5 years
Comment: Why "more than other EU"?
Comment: @Ulkoma- as Crazydre says Irish people have special rights in the UK that go beyond other EU citizens. We can vote in UK general elections immediately for example, with our Irish citizenship, which other EU citizens cannot unless they acquire UK citizenship. This is because Irish people have never been considered "aliens" under UK immigration law- we were formerly the same country and held a common citizenship, and this persisted even after independence. Even after that we never acquired the status of "alien". Most rights are reciprocal with UK citizens in Ireland who have a similar status.
Comment: @IvanMcA The UK's rules for Irish do involve slightly more restrictions than the reverse though. For example, British are completely immune from Deportation from Ireland, while the reverse is not true (though it's harder for an Irish Person to be removed from the UK than for another EU national)
Answer: Canada does not not check passports on exit (at last not at airport). You will not need to show any passport to Canadian authorities when you leave. You will need to show a passport to the airline.
The only important point is that you need to show your Irish passport to UK immigration on entry. Canadians are allowed to enter the UK without visa, but if they ask you why you are coming to the UK and you say "to live there" they will need proof that you are allowed to do so. Your Irish passport gives you that permission. Your Canadian one does not. Your Irish passport also allows you to use the EU line.
You also need to present a passport to the airline to prove that you are allowed to enter the UK. It doesn't matter which one you choose, since both Canadian and Irish can enter the UK without a visa, and the airline will neither ask nor care what your purpose in coming to the UK is. Using your Irish passport is probably marginally simpler, but there is no problem with giving a different passport to the airline from the one you will be entering the UK on. make sure you have both available of course.
Comment: Canadians have a right to enter the UK without a visa for tourism but that they do not have the right to remain forever that Irish people do. There is a possibility that the airline would look for a return ticket from a Canadian but not from an Irish person.


Ubuntu 13.04 dual boot with Windows 8 - Ubuntu only boots in legacy mode

Question: I've installed Ubuntu 13.04 in EFI mode on my dell inspiron 15z successfully.
When I boot my laptop in UEFI mode with secure boot off, I get blank Ubuntu screen - I got no activity on hard disk LED indicator - Ubuntu is not booted. But if I change boot mode from UEFI to legacy, Ubuntu works fine. In fact, right now I am writing this post from Ubuntu.
Also Windows 8 is not in the GRUB menu. Can somebody tell me how I can add Windows 8 to the GRUB menu and how can I boot installed Ubuntu in EFI mode? I've tried to use boot-repair before, but it didn't go well.
[dead link to boot info summary removed]
Answer: Your Boot Info Script output is a bit puzzling: It shows a GUID Partition Table (GPT) disk, which means that Windows will boot only in EFI mode. There's also evidence of an EFI-mode Windows boot loader. So far so good. It gets puzzling in that there's no evidence of GRUB on the hard disk, either in EFI mode or in BIOS mode; but there is evidence of a BIOS-mode Windows boot loader. My suspicion is that the Boot Info Script has simply mis-identified the BIOS-mode GRUB as the Windows boot loader. Certainly that's the simplest explanation that also explains why you can boot both Windows and Linux; however, it could be that something else is going on.
If I'm right and you've got a BIOS-mode GRUB, then you'll never get it to chainload to your EFI-mode Windows; that's just not possible. You could, though, use my rEFInd boot manager to switch between EFI-mode Windows and BIOS-mode Linux. You'd need to:

Install rEFInd in Windows, as described in the documentation.
Edit the refind.conf file: Uncomment the scanfor line and ensure that hdbios is among the options.

The result should be that rEFInd will enable you to boot to Windows or to GRUB, and GRUB will then boot Linux. You could also try an EFI-mode boot of Linux by installing an EFI filesystem driver for your Linux filesystem (probably ext4fs). Given what you've reported, this might not work now, but it might work in the future, once drivers and default configurations mature for better EFI support.
Keep in mind, though, that I'm very uncertain about any of this; it could be that you're actually booting Linux in EFI mode. If so, a tweak to GRUB's configuration might work, or installing rEFInd and its ext4fs driver would also work.


Population Within Radius

Question: I'm working on a personal project studying catchment areas for local travellers, and I'm looking for a way of finding population (& possibly GDP as well) within a radius of a point. I've been checking out census sites, but within a radius has been something I have been unable to find, particularly when I'm trying to do so in bulk (~40,000 times). Could someone point me in the right direction?
Comment: what geo data do you have (i.e. lat&long, zip code)?
Comment: also, what programming skills do you have?
Comment: I have lat/long, and programming-wise, I am a software developer, I use primarily Java, C++, and C.
Answer: I have not done this before, but I do not think you can get exactly what you want (population + GDP) within a radius. You can get population/GDP/demographics down to a census tract. Here is what I would suggest as a rough method (in pseudo code), assuming your radius stays within a US county.

Get the census tract KML datasets from US Census.
For the point of interest (POI)
A. Determine which county the POI is in.
B. Determine which census tracts are in that county.
For each census tract determine if the census tract polygon is following within the circle defined by the POI and radius.
A. If so, include the population and other data as part of the radius
B. If not, determine if the polygon intersects the circle.
C. If so, use a rough approx. of how much of the population data for the census
     tract to include (e.g., 50%).

The US Census KML datasets can be found here:
http://www2.census.gov/geo/tiger/KML/2010_Proto/
Comment: For higher resolution but less timely, you can use the shapefiles which have 2010 population and housing units stats as attributes: http://www2.census.gov/geo/tiger/TIGER2010BLKPOPHU/
Answer: I have done this with different goals. It depends on the resolution you want. My primary approach was similar to above: Create a circle of the radius desired, then use a spatial intersection code to ask if the tract/tract centroid lies inside the circle. I did it with block groups in R and it worked fine. There are lots of tools for that in R, python, postgis.
However, if you want to fine tune it, you can use change of support code
http://cran.r-project.org/web/packages/spBayes/
to change the estimates from tracks/block groups to a fine grid, then apply your code. If you change your support to a hexagonal grid you can get a pretty good estimate.
Comment: Interesting approach.

Population Within Radius


Deciphering foreign code

Question: What is the best strategy to go about understanding some one else's code for a medium sized project, if the code is not well documented and does not adhere to many coding standards?
Comment: See - http://programmers.stackexchange.com/questions/76347/how-do-i-get-started-with-the-source-code-of-open-source-projects
Comment: What makes it foreign? I have had coworkers that sat less than 6 feet away from me that wrote code like you describe! And they were the same nationality as myself! ;)
Comment: By foreign I mean source code written by someone else, sorry for the confusion!
Comment: Refuse the job immediately because a bad documented code is usually dirty. The best is to put everything in the bin and start a new project from scratch !!
Answer: My approach:

Play with the app (use it)
Check the code organization (layers/entities etc.)
Generate references diagram (i.e. using NDepend for .NET)
Look for some code patterns in code (this will give you some ideas what the author(s) tried to implement)
Don't dig into details too deep at start.
Focus on understanding the dataflow (i.e. how are lists populated, how is data saved, for example: UI->BusinessLayer->DataAccessLayer->SLQ Stored Procedure)
Answer: I'm assuming there are no unit tests.  The best way I've found is to take the time to follow the workflow; see how it interacts from the user's point of view and try to see how the code is called - then you can rename things to be more meaningful.
Answer: The first thing I would do is read about the project and use it, from a user's perspective. Read the Software Requirements Specification (SRS), user stories, or whatever form of documentation exists for the requirements. Then, try to complete some of the core tasks and understand how the system is used. I feel that if you don't understand what the system is supposed to do from a user's perspective, it's incredibly difficult to design and implement solutions to problems these users are facing.
One technique would be to read design documents and follow through the code. Dynamic diagrams (sequence and communication UML models, for example) are especially useful, if you have them. These enable you to see a graphical representation of the relationship between code modules (packages, classes, and methods). Of course, static diagrams (class, package, object, deployment UML models) are also useful in understanding how pieces of a system fit together. If these diagrams don't exist, spending a little time reverse engineering the system might be a good learning exercise.
Given your situation, though, it sounds like documentation might not be available. The next option would be to use a debugger. Turn on the debugger and walk through the system as its running to see how it fits together. You can run through several common use cases and step through methods. It might be a good idea to comment files as well. Perhaps make notes of things that you question or need to learn more about.
Answer: I would start with finding out what the code is supposed to do. Is it a web application that processes banking transactions? A desktop application that HR uses to manage resumes and applicants?
Next step would be to try running it. Explore one feature well. Then put breakpoints in the corresponding code and step through it with the debugger - if you are able to. This will let you see the "living" code - how it works when it is actually running. If the documentation has been poorly maintained, the debugger might be better than any documentation as it's possible that the documents have not been udpated as the code changed.
It is also be good to ask someone else in the organization who has more experience with the code, assuming that such an individual is available.
As others have mentioned generating diagrams can help if you have tools that are good at it. But keep them small at first. A diagram that contains hundreds of classes and possibly thousands of relations between them is pretty useless (at least at the begining).

Deciphering foreign code


In wubi installed ubuntu, is '/host' needed?

Question: I had windows 7, and i installed ubuntu 10.04 with wubi. when i did it, it created a 17gb partition, with out putting much data in it. it is called 'New Volume' and it is mounted ad '/host', it is also NTFS and accessible by windows. can I delete the partition?
Answer: No. Host is the mount point for your windows partition. You shouldn't delete it.
Answer: Sounds like the Wubi install did not work properly. I have done Wubi install on XP systems and Ubuntu is installed in a WIndows directory named "ubuntu". The Windows boot set up is modified to allow booting into ubuntu after the install (also a couple of Wubi loader files are stored on the "C:" disk). Wubi should not have created any partition on the hard drive. It sounds like you did a regular "Ubuntu install (in its own partition) and not a Wbi install. If you are not familiar with Wubi, it asks if you want to install Ubuntu and that installs it in its own partition NOT in a Windows directory. They need to really clarify this. With a "Wubi install ("ubuntu" Windows directory), you will find a sub-directory called disks. This is where Wubi creates "virtual disks" (filetype = .disk). Depending upon HD space, it will create a "root.disk" and a "swap.disk" or a "root.disk", "home.disk", "usr.disk" and a "swap.disk". Once you boot into Ubuntu, you can see the Ubuntu file system (Places -> Computer -> File System). Opening the "file system directory", you will see directories such as "bin, "etc", "home" and "host". The "host" directory is the Windows disk that contains the "ubuntu" directory.
Another alternative if you wish to avoid partitioning to allow Ubuntu (non-Wubi install) to run in its own partition would be to download and install the Windows version of "Virtual Box". Then you can "install" (again, on virtual disks) Ubuntu and start it up while running in Windows - this would allow you to flip back and forth between Ubuntu and Windows whereas a Wubi install (or Ubuntu native in its own partition) requires rebooting to switch into Windows. Virtual Box is open source and free. You can google it and download from SourceForge or other reputable sites.
Please, Linux purists, I know Ubuntu can be loaded into its own partition, but some of us have reasons for NOT doing it that way. So NO comments as to why this user doesn't get rid of Windows or go through the partitioning and native install (where many a newbie has wiped out their MBR or Wndows systems or worse).
Comment: Why not install it on a different partition... Well no, 3 partitions and the 17gb one wubi seems to have made. I just want to delete it to add space to my 159mb /opt partition. Can I?


Why was my answer voted down?

Question: My answer to a question was down voted. I realize it is not the apocalypse, but the answer did provide assistance to the OP's question with a concern for safety. Wouldn't it have a more positive impact if when an answer that appears to be unfounded or inconsistent; that a down vote offer an explanation and reason? Even anonymously.
Comment: Looks like the answer got one down vote, and one up vote.  The down vote could have been because your answer doesn't really answer the question. The OP wants to know if the nails being so close to the edge of the joist is unsafe, and if there's any code that specifies how close to the edge of the joist nails can be placed.  Do you feel you've answered one or both of those questions?
Comment: OP's first question was answered in my first sentence . But the idea of an answer is to offer a constructive response that at the very least , as stated on "help" page for new members, "Any answer that gets the asker going in the right direction is helpful, but do try to mention any limitations, assumptions or simplifications in your answer. "   I really don't want to make an issue and take up more of your time. It's not a big deal. I was just curious and wanted to learn the rules. So thanks for the help Tester101. I see your replies and picked up some good info from them.
Answer: This has come up many times before all over the network, most notably here:

Encouraging people to explain downvotes

and the consensus is that asking people to explain down-votes would be counter productive at best.
All you can do is analyse your answer with fresh eyes and see if there is anything you missed first time round.
Comment: Thanks for the response. And your last sentence is what made me post my question. A solution might be to have the person that see's a problem in an answer to highlight the specific word or words. This can be done anonymously and at the very least provide a clue as to the problem with in the answer.

Why was my answer voted down?


Guerrilla usability testing

Question: I want to do a guerrilla usability testing and I was wondering if it is ok to ask to the participant to draw/sketch his thoughts as well?
Comment: Tester = the person giving the test. Why is this individual  drawing *during* the test, instead of being prepared. Guerrilla testing still has clear structure and goals, the environment and participants is just less formal.
Comment: Sorry I mean the participant not the tester.
Answer: Make the participant feel comfortable
Ask the user to do whatever they feel comfortable with to clarify an idea. Some people are going to freeze when you ask them to draw anything. Others will grab your pen and a napkin at the first opportunity to avoid fumbling with words.
Unless you are doing it with a very precise psychological goal in mind, you don't want to take a participant too far out of their comfort zone. They will clam up and stop thinking and communicating clearly. That won't do you or them any good.
Comment: I strongly concur with this answer. Guerilla testing allows the tester some flexibility in their feedback. Restricting them to drawing a picture is no better than restricting them to multiple choice, the medium of dance, or any other form of art. The key is to put the focus on the results of the test rather than the structure of the communication

Guerrilla usability testing


Why not separate a tilt shift lens into two separate lenses?

Question: When using a tilt shift lens I find myself using the two features of tilting and shifting for separate photos. If I want to control the depth of field such as in a portrait or macro shot I will tilt the lens. If I want to control the perspective such as in architecture I will shift the lens. That brought me to thinking, they both seem like very complex movements of the lens, so why not separate them into their own dedicated pieces. This would seemingly save on costs and simplify the design significantly. I might be missing a key feature of combining the two features together, but I have not encountered that so the question still perplexes me.
Answer: Well, to begin with, a tilt-shift lens is a rather limited substitute for a proper bellows setup with free movement of the front lens. Offering only shift or only tilt makes that even worse. That said, shift-only SLR lenses have been made, such as the 35mm Nikkor PC "Perspective Control" from the early sixties. Canon answered with a tilt-shift lens in 1973, says Wikipedia, and after that the marketplace hath spoken - yes, we'd like both tilt and shift in one lens, please. Anyway, a T/S lens is in principle just a medium-format lens on a purely mechanical tilt/shift mounting, it's not exactly rocket science to design and manufacture this.
The high price has more to do with very limited demand and correspondingly small production volumes (plus that the Canon versions at least are absurdly well-built, similar in feel to early EOS L lenses before they started to use plastic), dividing it up into separate tilt and shift versions could only make this worse.
Comment: There are, however, entire cameras built around the shift-only principle, like the Alpa STC, a rather expensive way of using a (rather expensive in its own right) digital medium-format back. You give up Scheimpflug, but gain ruggedness. The main use would be panoramic, I'd guess, rather than perspective control; you can effectively cut the focal length of a given lens in half without suffering the consequences (vignetting or degrading filters, barrel distortion, field curvature, flare, etc.).
Answer: All the SLR tilt-shift lenses I've used have had a tilt action that shifts the tilted lens elements relative to the centerline of the untilted lens, resulting in a noticeable and significant shift of viewpoint when tilted. Including a shift mechanism (that can be rotated to act parallel to the tilt mechanism) provides a simple way to compensate for that shift when positioning the camera to accommodate it is not feasible.
Answer: Sounds like you really want a view camera. They are great for controlling dept of field during product shots. or for hard core macro shots. I'm a bit confused how you'd use it for portraits, most of the time, you want the eyes in focus. View cameras are a PITA to use, but they can tilt separately from shifting, tilt in two axis, etc.
Used view cameras are cheap. Some bloggers, such as Alex Koloskov, use a FF digital camera as the back. There are, of course, medium format digital backs, but they are wicked expensive.
Comment: There are "mini-views" available (and no, they're not cheap) designed specifically to use 35mm-type (full-frame or crop) cameras as the back. This isn't ideal, of course, since the distance between the mount and the sensor (and the resulting mechanical vignetting), along with the restricted acceptance angle of the sensor's microlens array, means that back swing and tilt (and rise and shift both front and back) are severely limited compared to film. As for view camera portraits, well, this idea of small DoF is relatively new, and a small aperture/CoC and little enlagement solves that problem.
Comment: @stan, the good news is that with a view camera, you can adjust the bellows and correct any flange to sensor distance changes. Which means that in addition to being not cheap, they are complex.
Comment: it's not the flange-to-sensor distance that's the problem, it's the mechanical vignetting of the lens mount opening, combined with the acceptance angle at the sensor (oblique light doesn't strike the sensor directly; there's a small lens over each sensel in almost all 35mm and APS-C sensor assemblies). Even a bag bellows (the friend of the wide-angle large format architectural photographer) can't make up for those restrictions.


Do I need a transit visa if I have 9 hours of layover at Delhi airport?

Question: I have a valid US passport. I will fly Jet Airways to Delhi airport with 9 hours of layover to change to another Jet Airways Flight to Abu Dhabi. Do I need a transit visa?
Comment: Where is your first flight from - is it an Indian Domestic flight or an International one? Also, what's your nationality - that can (in some cases) make a big difference
Answer: If you're flying from the US via Delhi to Abu Dhabi with a US passport, you do NOT need a transit visa in India. Anything layover below 24 hours is covered under TWOV (transit without visa) rules.
Jet Airways staff is pretty helpful with regards to this: tell the ground staff on arrival in Delhi that you have a connecting flight and they will point you towards the transit area for international travellers.
Answer: You don't need any visa.
Just go to transit desk tell them what flight you arrived on and what flight you depart on and they will transfer your luggage for you. Once they (transfer desk staff) will contact someone from depart airlines, they will give you boarding pass (it can take a while), so you will be able to move on forward to duty free area and the gates.
Don't worry.
Answer: If you don't leave the airport why would you need a transit visa?
I've had long layovers in various airports in the world and if you don't try to leave the airport there's no reason for someone to treat you like you're entering the country.
Sorry you're spending 9 hours in Delhi airport though... the city has lots of cool sites but the airport is NOT one of them.  If I were you I might want to get a visa just to make decent use of that time rather than spending it in a sorry airport.
Comment: Not all countries treat transit travellers as you describe. For example, everybody flying into the USA, even if it's just for transit, must pass through customs and immigration (and have a valid visa, if required by their nationality or purpose of travel).
Comment: Also in the UK many nationalities need an airside transit visa (even if you never leave the airport); similar rules apply for the Schengen countries.


Fermentation has not started been 48 hours.

Question: Put liquid yeast in wort cooled to 70 degrees. My yeast was at 78 degrees not 70 degrees no bubbles yet.
Comment: Also, could you specify what yeast you used?
Comment: Still no bubbles/progress in fermentation?
Answer: If it is still not bubbling or showing positive signs of fermentation then IMHO the yeast should be re-pitched ASAP. This time make up a starter to check the yeast to be pitched is actually active before pitching it. I would also recommend that (at this stage) a double dose of yeast is used (eg 2 packets not just one). The priority is to get this brew fermenting in bulk before something else does that for you.
Answer: 48 hours is usually a long lag time. But not always.
For more detailed answer please post your wort OG, yeast type, yeast date, amount pitched, storage conditions of yeast, how was wort oxygenated.
I would keep it below 70° though, in all cases.
This may just be lost in language, but yeast needs to be added after wort has been chilled to pitch temp.
Answer: I would also have to ask if you are certain the seal for your lid/cover is working 100%?   I recently assumed that a saison I had just created wasn't fermenting and discovered that the gasket on the lid of my fermenter wasn't properly aligned and was allowing C02 out so there was no activity in my air lock.  A quick fix and all was well.
In other words - check your setup and do not assume.
Can you observe a krausen on the top of your beer?
Answer: I agree, 48 hours, you should probably see something indicating that fermentation is taking place. No foam, no bubbles, however slight? Some yeasts are quite temperature sensitive, requiring a specific range to activate and work properly, however, I don't feel that 78F would be too high to kill most yeasts.
If your liquid yeast was outdated or improperly stored, it may be bad.  You can add a bit of yeast nutrient and/or energizer to give it a helping hand and see if that stirs things up.
Did you oxygenate your wort with either an oxygen tank or serious stirring? Maybe that's an issue contributing to the slow start.