Specifying Struts templates source

Question: Say I'm using a form with a text-field.
<@s.form action="login">
        <@s.textfield label="E-mail" name="email"/>
        <@s.submit value="send"/>

How can I specify that the text-form should be generated by a custom template (text_login.ftl) rather than the standard text.ftl?
Answer: I did it few years ago, and as I remember I did the following
1) created my own template in forlder
src/template/_theme_/_template_.ftl

theme - it is name of theme used in struts tag definition (see below). E.g. ajax (already defined and existed in Struts2 theme)
template - name of your template. E.g. inline-submit:
src/template/ajax/inline-submit.ftl

2) now in jsp, when I want to show that some tag should use that template, I wrote the following:
<s:submit theme="ajax" template="submit-inline" ... />

that's all.
In your case you need to write something like that:
<@s.textfield label="E-mail" name="email" theme="_DEFINE_WHERE_TEMPLATE_IS_LOCATED" template="text_login"/>

Specifying Struts templates source


How can I decide between the 70-300mm vs. 100-400mm Canon L lenses?

Question: My current lenses:

Canon EF 50mm f/1.8
Canon EF 70-300mm f/4-5.6

I'm interested in wild life photography and landscape photography. I want to pick up my first L lens soon, and I am debating the 70-300mm vs 100-400mm. The only thing that is erking me to not get the 400mm is the push and pull zoom and the non weather sealing, also the 70-300 have better optics. However, seeing how I already have the substandard non L 300mm lens, which one should I pick up?
Comment: You are planning to sell the 70-300 that you currently own, right?
Comment: I agree with dpollitt here...if your going to pick up either the 70-300L or 100-400L, you should sell your 70-300 non-L. Its doubtful you would use it again, either way, even with the 100-400L in your kit (the 30mm wider focal length on the short end is rarely useful for wildlife...you'll be at 400mm most of the time, and maybe around 300-350 for the few rare occasions where you actually get close enough to your subjects to use it...although you lose a lot of background blur when you do.)
Answer: If your interest is wildlife, as someone who photographs wildlife and birds myself and uses this very lens, the Canon EF 100-400mm f/4.5-5.6 L IS is the lens you want. From a price/performance standpoint, it packs a LOT into a relatively easy to handle package, offering the benefit of a zoom and the bulk of L-series quality (lacking only wide-open sharpness at the long end.) This is a fairly old lens design...over a decade, if I remember correctly. There are a lot of anecdotes on the net that are frequently regurgitated on forums by people who dislike the push/pull design, however most of them are unfounded and based on speculation.
The Wildlifers Lens
First off, the good stuff. The EF 100-400 is well-known as a key lens for wildlife shooters. It has an ideal amount of reach, especially when paired with an APS-C camera for extra reach (it effectively becomes a 162-648mm lens on say a 7D, 60D, 650D, etc.) It also doubles as a decent lens for bird photography, however its about the minimum you would really want to use for that type (a 500mm f/4 or 600mm f/4 L-series lens, preferably with a 1.4x TC, or a 300mm f/2.8 with a 2x TC, is far preferable for birds as you need all the reach you can get, but the 100-400 will definitely do if you can't afford to drop seven to ten grand on a lens. ;) At 400mm, you are pretty much at the sweet spot for a lot of wildlife types...including ungulates (elk, deer, etc.), canines (foxes, coyotes, even wolves if your brave), and a whole host of rodents and other smaller creatures.
The EF 100-400 has IS, or image stabilization, which is pretty much essential for wildlife and bird work. It is not a top of the line, modern IS system...those will get you about four additional stops of hand-holdability (but it costs!) The EF 100-400 will get you around two stops, which means you can shoot fairly sharp hand-held shot at a 1/100th second shutter speed. For wildlife in the evenings, thats extremely handy (although you might have to use an ISO setting a stop higher than you might prefer.)
Generally speaking, the 100-400 is a sharp lens. At less than 400mm, its pretty sharp up to 1/3rd of a stop down from wide open. At 100mm, f/4.5 is sharp enough. At 400mm, this lens is tack sharp at f/7.1. For most things, unless you are shooting in very low light (such as wildlife 15-20 minutes after sunset), you should be able to shoot at f/7.1 without issue. Wide open @ f/5.6 at 400mm, this lens does get a little soft, however it is still acceptably sharp enough that it can serve in a pinch. A bit of post-process sharpening can do a lot to improve results as well.
When it comes to functionality, personally I find this lens to be excellent. There are a lot of nay-sayers on the net who trash the push/pull zoom design with an often astonishing gusto and glee. I would venture that very few of those individuals have actually used this lens for long enough to actually realize the potential such a design has. Even if you are used to lenses that have dual rings for adjusting focus and zoom, it does not take long to get the hang of a push/pull design. There are several benefits to this design as well. For one, it allows for very quick adjustments in zoom, much faster than can generally be achieved with a ring-based design (you can zoom from 100mm to 400mm in less than a second if you really need to.) The design also makes it easy to adjust both zoom and focus simultaneously since the adjustments are decoupled and require very different actions to perform, something that is rather difficult to do on a dual-ring design. The USM focus with full-time manual focus works superbly by a focus ring. The ability to give focus a quick manual adjustment to get it within range of your subject on the rarer cases where AF does act up means you spend less time hunting and more time shooting. With the push/pull design, you can even make those manual focus adjustments while zooming...a rather unique capability of this lens.
The Potential Detractors
There are a lot of nay-sayers who greatly dislike this lens, and several anecdotes that are regularly repeated about why this lens should be avoided. I believe only one might actually matter.

"Its push/pull design is horrible and completely unintuitive."

This is really a matter of preference and personal choice.
Learning the push/pull design is not hard, and once mastered, is quite flexible and powerful.

"Its a 'dust pump', and will suck tons of junk into your lens!"

Completely false. This lens is not a weather sealed lens, however it is FILTERED to prevent dust in the barrel.
Unless your working in a dust bowl and are getting pummeled by extremely fine, micron-sized dust, its unlikely your ever going to accumulate enough particulate inside the lens to matter.
I've used this lens for over two years in heady rain, snow, sleet, hail, dust storms and other blowing particulate, and never had any issue...so despite not being weather sealed, it still holds up quite well against the onslaught of nature!

"Its a dog to focus because of its aperture, the 400 f/5.6 is better."

This is not as fast as the top-shelf f/4 and f/5.6 L-series supertelephoto lens like the 500mm, 600mm, or 800mm lenses from Canon (but neither does it cost $10 Grand or more!!)
This lens is plenty fast enough to perform continuous-tracking AF on birds in flight when using a Canon 7D in low sunset light.
This lens is plenty fast enough to acquire focus lock on wildlife in post-sunset light (which is dimmer than BIF AT sunset!)
This lens is even capable of autofocusing at f/8 with a 1.4x TC in daylight or sunlight (something not officially supported, but which is possible using a Kenko 1.4x DGX TC).

AF can be spotty at f/8, however thats kind of run of the mill for f/8 AF on most Canon equipment, even 1-series bodies.

"Its unusably soft (not sharp) and useless for wildlife or bird photography."

It CAN be soft at 400mm f/5.6 (max aperture), more so in the corners.
Stopped down to f/6.3 it gets quite acceptably sharp.
Stopped down to f/7.1 it gets tack sharp.
Given that you'll probably need to be shooting at f/8 most of the time for wildlife and birds anyway except when in very low light, your shots should be tack-sharp pretty much all the time.
Canon AF is always performed at maximum aperture, the shutter only stops down electronically after AF lock is in and the exposure is taken.

"Its too heavy for walk-around use for more than an hour."

This lens weighs only three pounds. Just slightly more than the 400/5.6 (2.7lb) or 300/4 (2.8lb).
In contrast, the other most popular lenses for wildlife and birds weigh considerably more.

The EF 300mm f/2.8 weighs 5.7 pounds.
The EF 400mm f/2.8 weighs 8.5 pounds!
The EF 500mm f/4 L weighs 8.5 pounds!
The EF 600mm f/4 L weights 11.8 pounds!!

Without any kind of strap at all, I've found you can walk around with this lens for several hours without it being a problem. Holding it at waist level by the tripod mount can help extend walk-around time.
With a shoulder-strap that rests the camera at your waist, you can walk around with this lens all day long without issue.
A 300mm f/4 might weigh less, but you also lose 100mm worth of reach, a non-trivial amount when it comes to wildlife, and unacceptable for Birds/BIF (unless you have some serious skill in sneaking up on them without being noticed!)

For its price, which streets at around $1400 these days, the Canon EF 100-400mm f/4.5-5.6 L IS USM lens is hard to beat. You get a 4x zoom range, L-series build and optics, 2-3 stop IS (about 2 stops @ 400mm), a very sturdy build, and relatively low weight compared to Canon's other supertelephoto lenses.

Potential Alternatives
Ok, now that sales pitch for the 100-400 is over (sorry, have to put some facts strait when there is so much misinformation and nay-saying about that lens!). There are alternatives to this lens. Canon does offer the 300mm f/4 L IS and 400mm f/5.6 L. Both of those lenses weigh slightly less, however they have their own potential drawbacks. There are also third-party zoom lens options, however I do not believe any of them actually compare to the price/performance/features ratio of the Canon 100-400mm.
Regarding the Canon EF 400mm f/5.6 L lens. This is frequently listed as an ideal option for wildlife and bird photography. It has a single, and in my opinion fatal, detractor: It lacks any form of IS (image stabilization). For birds, thats a total dealbreaker, and for most wildlife, its usually a dealbreaker as well. If you have extremely stable hands or are already a skilled hand-held, non-IS panner, this might actually be the lens for you. It might also be a good lens if you always intend to use it on a stable tripod with a gimbal-type tripod head and lens mount. Its slightly sharper than the 100-400 wide open, but usually still needs to be stopped down to f/6.3 or f/7.1 for maximum sharpness. I've met a fair number of Canon 7D users using the 400mm f/5.6 out in the field as well, and heard their surprise when they tried out my 7D+100-400mm setup with its image stabilization. The list price on this lens is $1799, which deters most people, however the street price (actual sale price in most cases) is closer to $1400 (I believe I picked mine up for around $1580 minus a refund deal from Bing Shopping a few years ago, so it ended up being around $1420 or so). Thats just in line with the 400/5.6 L, and the 100-400 does offer IS...making it a more attractive option for 400mm handheld wildlife/bird photography. To keep things simple, you really want image stabilization for wildlife!
The Canon EF 300mm f/4 L IS is another option. If you want a sharp prime, this is a great lens. Its quite sharp wide open at f/4, and about as sharp as it gets at f/5.6. The big improvement with this lens over the 100-400 would be corner sharpness...its one of Canon's best corner-sharp lenses for the price (the next best thing would be the 500mm or 600mm f/4 L, which are two of the sharpest lenses Canon offers...but they sell for around ten grand.) The key drawback with this lens is the focal length. The loss of 100mm is quite a big loss, and will mean you either have to get a fair bit closer to your subjects (which, in the case of wildlife, is difficult...you either scare it off or increase personal risk.) At 300mm, outside of using a bird blind and sitting and waiting for the birds to come to you, your probably going to be out of useful reach of most birds and BIF.
There is an option for this lens to improve its versatility, and still be a bit sharper than the 100-400. Slapping on a 1.4x teleconverter converts this lens into a 420mm f/5.6 lens. The benefit of this lens over the 400mm f/5.6 is that it has image stabilization! Even with a TC, at 420/5.6, this lens would make a great wildlife and birding prime. The drawback is you'll need to spend an additonal $300-$500 on either a Kenko DGX or Canon 1.4x teleconverter, which makes the total price around $2000. If you have the money and want the sharpness, I'd say this is the better choice over the 100-400. Even with a TC attached, the EF 300 f/4 L has a size advantage over the EF 400mm f/5.6.
The Canon EF 70-300mm f/4-5.6 L IS USM is a decent lens. It is one of Canon's newest lenses, so it is a more advanced design than the 100-400, 300/4, or 400/5.6. It has great optics, sharp to the corners wide open, and has superb IS. As a general purpose telephoto lens, its probably one of the best options out there. It could serve as a wildlife lens if you needed it to, as well as a portraiture lens. However it doesn't really have ideal characteristics for a wildlife lens. It maxes out at a 300mm focal length. That is generally not quite enough reach to really get good frame-filling wildlife shots (400-500mm is better). Its also f/5.6 at 300mm, so if you tried to use a 1.4x TC to get 98-420mm out of it, you'll be stuck at f/8 on the long end (and probably be unable to AF, although you might be able to with a Kenko DGX, like on the 100-400.) Its certainly an option, however being a newer lens its likely to sell closer to its list price of $1599.
There are also a bunch of third-party options. Sigma, Tokina, Tamron, etc. all make lenses for the EF mount. Most of these lack the optical, build, and functional capabilities of Canon lenses, and usually have tighter maximum apertures (f/6.3 in many cases.) They are usually cheaper, sometimes quite a bit cheaper. You might be able to pick up a Sigma "Bigma" 50-500mm lens for a decent price, however its going to be just a bit worse characteristically than the EF 100-400mm lens.

Top Choices
In conclusion, if I had to recommend two options, these would be them:

The Prime Option: Canon EF 300mm f/4 L IS USM + Kenko 1.4x Teleplus Pro 300 DGX

For better sharpness and ideal reach for wildlife
A bit higher cost (needs an extra TC, for about $300) and less versatility (no zoom)

The Zoom Option: Canon EF 100-400 f/4.5-5.6 L IS USM

For the best versatility at a great price/performance ratio
Not quite as sharp as the EF 300+1.4x TC

Both options weigh the same, and offer roughly the same reach. If you don't care about zooming and have the cash, I'd say go with the prime option. Better optics, 20mm extra focal length for more reach, and slightly better IS. The whole getup will probably run you around $2000, but its probably worth it.
If you don't have the cash, the EF 100-400 really is the best lens for what you want to do. Its relatively cheap, it only weighs 3 pounds, and at 400/7.1 its as sharp as any other Canon L-series lens. It'll serve you well.
Comment: Actually, I've taken a fair number of landscape shots on the 100-400 as well. I've also used it for pseudo-macro shots, too. I guess I could add that...but its a pretty big answer already...
Comment: Great answer! I will say, the poster was asking about wildlife and landscapes, and not wildlife and birds, which seems a bit different to me. I think the 70-300mm f/4-5.6 L IS might suit them just as well as the 100-400mm which was the main question being asked here. You were more just arguing how great the 100-400 is here, which I agree with ;)
Comment: He mentioned landscape, however he was explicitly asking about a wildlife lens. I threw in birds because the 100-400 is a good entry-level birding lens as well...more for completeness of the answer than anything. Don't underestimate the difference 100mm makes. You could use the 70-300 L, but your probably going to be cropping quite a bit to simulate frame-filling shots. In my experience, the 400-500mm range is pretty much the sweet spot for a lot of wildlife, and 400/420mm will produce some GREAT boke.
Answer: You don't seem to mention which body you're using (or I have a very specific kind of blindness), although from your lenses I'd suspect a FF body.
You should try to rent them. No on-line opinion can match your own impressions: you could end up buying the wrong lens (for your usage) and trying to persuade yourself all is well, despite obvious "problems".
That being said, I rented the 100-400L, using a 7D, giving me an effective reach of 160-640mm in 35mm terms. While shooting people and family I mostly used the 160-350 part of my range (and often tried to pull closer than 160mm - the main reason I'd rather go the 70-300L way, on my crop body). But when shooting wildlife, I almost exclusively used 640mm, while wishing for more. You just can't get too close.
In the same setting, you'd be limited at 400mm, unless using a 1.4x or 2x converter (canon's converters don't work with the 70-300!). 400mm is, this is a harsh statement considering I rarely shoot wildlife - it's more of an opportunity thing, way too short for wildlife. Using converters could give you the needed reach ,to get close to your subjects, while at the same time slowing down your lens. If you can't push up the ISO high enough to counter the speed loss, that can be quite frustrating.
So it's back to you, see how serious you are about shooting wildlife, if you can afford a (quite expensive) lens dedicated to that.
Just one last bit: the push-pull is quite useful when shooting wild-life. You can scan around at 100mm, and when you see a subject quickly push to 400mm and snap that picture. It also helps if you happen to lose your subject (a quite easy thing to do at long focal lengths). Pull back, correct and push ! I also don't agree on the zoom creep: there's a special ring to adjust the tightness, and after a while you start to develop a way to tighten and loosen the lens unconsciously.
Answer: Another option to consider, ASSUMING that your 70-300mm f/4-5.6 is the base model and not the 70-300mm f/4-5.6 IS USM model:  purchase the 70-200 f/4 L. The optics on this lens are dramatically better than the base 70-200, and marginally better than the IS USM model. The focus and build quality are far better than the other two lenses.  Plus, you can purchase the 70-200 f4 L for around $600.
Beyond that, the 70-200 f/2.8 L (or far more expensive IS model) are as good as the f/4 L, but much brighter (and bigger).
Again, if you do NOT have the IS USM 70-200, this is a very good option, and while you lose 100mm vs the 70-300L you mention, you get constant aperture, and far lower price than the 70-300 f/4-5.6 L lens.
Answer: The optical different between the standard 70-300mm and the 70-300mm L is way too big. I have used the 100-400mm and its' a very big and heavy glass, not suitable for longer periods of use. At first it felt like 10 lbs but at the end of the day it grew into atleast 100 lbs! On the other hand, the 70-300mm L is very sharp, comparatively lightweight, can be used without a tripod/monopod. Also, the push/pull zoom of the 100-400mm did not impress me, the zoom ring is not tight and often drags off when faced downwards. You'll need to tighten another ring in order to prevent this to happen.
But, the 100-400mm is better in case of wildlife photography just because of its 100mm more reach. Within a few days, you'll get used to the push/pull zoom so thats' not a problem. So, if you're seriously into wildlife, the longer lens you have, the better. Therefore I'd pick the 100-400mm over the 70-300mm though the latter is slightly superior optically.
Comment: Well 100-400mm is not as long as you are thinking. 400mm is barely enough when it comes to wildlife and 600mm is ideal. So, yes, I'd still go for the 100-400mm. Your best bet is to rent both lenses, give each of them a try and decide yourself :)
Comment: The 100-400mm lens is around 3 pounds, a far cry from 10, and nothing close to 100. I use the 100-400 very frequently, for many hours a at a time (8-10 hours). Under continual use like that, it can get heavy to lug around without proper support, but a shoulder strap that rests the camera at your waist does wonders, and allows you to use a large camera like a 7D w/ grip + the 100-400mm lens for an unlimited time without problems.
Comment: At this point I am still a student and the best "wild life" that I can get are zoos... Nothing too insane like African Safari, should I still go for to 400m or invest in the 300mm and wait for Canon to update the 400mm?
Comment: I know I know. It was a joke! ;)
Answer: Avoid the 100-400L:

Very soft lens  compared to similarly priced shorter zooms (70-200 f2.8 or f4) or primes (400 f5.6, 300 f4)
Very slow focusing compared to wildlife oriented primes like the 400 f5.6 or 300 f4
Variable aperture lens means your shutter speed will change as your focal length changes which is frustrating when you've got everything else dialed in and that changes.
Push-pull zoom is a PITA to deal with, is imprecise and acts as a dust pump for your camera

I see you said you're interested in wildlife and landscape (I assume wide vistas)*, I'd suggest you figure out which type of photography you'd like to use your first L lens for and get a lens suited to that specific type of photography.  If you want to start with landscape look at some wide primes (24L 24L TS-E) or zooms (16-35L, 17-40L, 24-105L) and if wildlife is your goal I highly suggest you look at the 400L f5.6, its incredibly sharp and focuses super fast which is what you want for wildlife.
*I say 'wide vistas' because landscape can be whatever you want, I shoot a lot of 'landscape' photos with a 70-200mm or 135mm lens.
Comment: An additional note regarding push-pull zoom...your comment is anecdotal. The 100-400mm IS a push-pull design, which, having used it extensively for about two years, is actually quite genius and a dream to work with once you learn how. As for being a "dust pump", the lens has dust filtration to prevent any amount of dust from getting into the lens barrel. I've used that lens in rain, sleet, snow, and hail, under driving winds and dusty conditions, even hunkered down in fields of grass with pollen and grass seed or fragments flying around. Sealing is NOT a problem on this lens.
Comment: The 100-400L is only soft at the long end wide open. Stop down to f/7.1 and it is sharp as a tack, and given its DOF, you often have to do that regardless. As for AF, its not any slower than the 400 f/5.6 (its pretty much the same), it is a little slower than the 300 f/4, however it is more versatile and has extra reach. As for the 400/5.6 for wildlife, thats totally a no-go, as it doesn't have any IS to speak of, and camera shake will obliterate improvement in sharpness the lens may offer, and then some. The 100-400 has IS, and from a price/performance standpoint, is ideal for wildlife.
Comment: @jrista Saying the 400/5.6 as a no-go for wildlife because its lacking IS doesn't make sense, IS is important but its not a make-or-break thing especially since you should be shooting well over 1/1000s :)  Also, saying you can't complain about sharpness on a 'wildlife' lens if you just stop it down to f X.x makes no sense, with wildlife you want as fast a shutter speed as possible so you're always shooting wide open.  The 100-400 compromises too much in the name of versatility, *if you want to have a lot of options go for the 100-400, if you want to shoot one thing well pick a prime*.
Comment: I've shot wildlife hand-held with the 400/5.6. Camera shake is a serious issue with pixel densities as high as they are on APS-C cameras these days. As for aperture, there is no benefit of the 400/5.6 prime over the 100-400, since it too is f/5.6 at 400mm. If you intend to shoot out a car window with the camera resting on the door, then the 400/5.6 is an ok option, but its sharpness over the 100-400 is usually entirely mitigated by blur from camera shake, so its a net zero. With the IS, you can shoot the 100-400 @ 400mm at 1/1600s or more, and still keep your ISO to around 800.
Comment: I shot a lot of birds (long ago) while I owned both, but I must say I always used a tripod + gimbal so sharpness and focusing speed (on moving birds) wound up pointing the 400 f5.6 out as the winner.  One last nit, 'As for aperture, there is no benefit...' we established that wide open the 400L is noticeably sharper such that you have to stop the 100-400L 1-2 stops to get the same performance, so aperture is important on the two :)
Comment: Er, not 1-2 stops!! A mere 2/3rds of one stop at most, thats it!! One stop would be f/8, and two stops would be f/11. If you stop down to f/7.1 and were previously at ISO 800, you would only have to go up to ISO 1250 to maintain exposure. Were not talking about a very large difference in light here. If you needed more and didn't want to compromise on sharpness too much, f/6.3 will certainly do, and the difference in sharpness between that and the 400/5.6 wide open is minor.
Answer: I faced a similar decision last year.  In the end, I opted for the 70-300L due to its blazing fast autofocus.  The image quality is absolutely superb, and the AF is only slightly slower than the 300/2.8.  The improved IS is wonderful, too.  I can reliably shoot at 1/30th at 300mm.
Do you need 400mm?  Do you need it now?  There are rumors of a newer 100-400 coming out.  Then again, the new lens won't be anyplace close to the same price point.  Maybe $500-1000 more.
Answer: If you're interested in birds such as sparrows and blue tits then 300mm will not have enough reach. Youll be better with the panasonic 100-400 on micro four thirds. Thats 200-800mm real world.


Excel Comments - Max Length in 2003

Question: Anybody know what the limit is for the comments on an Excel cell (2003)?  I'm programatically filling this in and want to make sure that I don't exceed the limit.
Answer: This page list all the Excel specifications and limits.
Not sure about comments, but it seems cell data is limited to 32767 characters. Also not sure of the character encoding or if that matters.
Answer: Looked up the BIFF specification for NOTES (which are actually cell comments) and there is not a limit per se, only 2048 per NOTES record, but you can have as many of these as you like, they are marked as continuation records past the first one.  With this in mind, it seems limitless.
However, to be safe, I'm cutting mine at 15,000 (as we should never need more than a 1000 for what we are doing).
Answer: I just tried to give it a try by putting large comment programatically.
And I ended with result : 22877 chars. However I'm not sure whether character encoding matters.
Answer: According to "Excel specifications and limits" the the max number of chars is 32767 (only 1024 display in a cell).
I suspect that's characters on the assumption that no character ever takes more than 2 bytes...

Excel Comments - Max Length in 2003


What function does C1, C2, and Off mean on Sigma 120-300mm f/2.8 Sports lens?

Question: I am using a Sigma f/2.8 120-300mm lens. How does the C1 and C2 affect pictures? Also, what about the Off, 1, and 2 switch on the OS feature?
Comment: Have you checked in the [manual](http://www2nd.sigma-photo.co.jp/downloads/manual/120_300mm_F2.8_DG_OS_HSM_S013.pdf)?
Answer: Many cameras have 'C1', 'C2', etc. settings that allow the user to save a "preset" combination of specific settings that can be available at the flick of the mode dial.
Sigma's "Global Vision" series of lenses is similar. Many of them allow customization of things such as Optical Image Stabilization, Autofocus Speed, and Focus Limiter range. When the switch is set to 'Off' the factory defaults are applied to these parameters. The customized settings can be accessed by sliding the switch to the desired position. You can have one customization profile for 'C1' and a different customized profile for 'C2'.
To set up a 'Custom Setting', you need to connect the lens to a computer running Sigma Optimization Pro  via the Sigma USB Dock. The USB dock only works with Sigma's 'Global Vision' lenses: the Art, Sports, and Contemporary series. Other Sigma lenses are not compatible with the USB dock.
You can download the basic instructions for the Sigma 120-300mm f/2.8 Sports DG APO OS HSM.
You can also download the Instruction Manual for Sigma Optimization Pro.
There's a multi-video tutorial on how to use SOP.
There's a good bit about the customization options and how to use them at this review of the Sigma USB Dock from The-Digital-Picture. He also discusses the AF speed customization at the review of the Sigma 120-300mm f/2.8 Sports lens.
The switch on the lens marked 'OS' controls the lens' optical image stabilization feature.

'Off' turns OS off
'1' turns OS on in both the up/down and left/right directions
'2' turns OS on in 'panning' mode. The lens will detect which direction the lens is being panned at a steady rate and only provide stabilization on the axis perpendicular to that motion. If you are holding the camera in landscape orientation and panning from left to right, the OS will only attempt to correct for up and down movements of the lens in order to allow you panning motion during the exposure to be smooth instead of choppy due to the OS fighting your panning movements.
Answer: This Sigma lens allows you to make and store two custom user settings. Once programmed you can select which one is in effect i.e.  C1 or C2 via a switch. Additionally you can turn "off" these presets.
Programing this lens requires Sigma software for your computer and a specialized USB cabling. You can find out more if you read the manual that accompanies this lens.
You can select and program the motor speed of autofocus "AF Speed Settings".
You can set limits over the span of the distance of the AF distance range "Focus Limiter Setting".
You can set considerations as to how the optical stabilization operates "OS Settings"
Comment: interesting. I did not purchase this lense. I am only renting it, therefore any instructions did not come with the lense


Basic PNP transistor on a microprocessor output pin

Question: I have a 5v microprocessor that needs a PNP transistor between it and the common anode of an LED display, as it can't source enough current to drive all of the LED's without burning up. I understand in principle how the transistor connects, but seeing as I'm a computer programmer and not an electrical engineer, I'm having a little trouble finding the exact part number or specifications that will work in this application (all this talk of bias voltage, forward and reverse biasing, etc. has me thoroughly stuck). The display should suck around 400 mA through the transistor, worst case, and everything runs on 5 volts. Lastly, will I need any resistors (aside from the LED resistors) on the transistor and if so, how do those work?
Comment: Again, sorry if this is a really basic question, but I'm just getting into EE by teaching myself, and I've had trouble forming a coherent answer by looking at the 'net. Thanks for any help!
Answer: What you want is something like this:

except that the parts for individual LEDs will be replicated 16 times instead of just 4 as shown.
Since you have 16 LEDs each drawing 20 mA, the total current when all are on at the same time is 320 mA.  R1 will cause about 10 mA base current in Q1 when the processor drives the common enable line low.  That means the transistor needs to have a gain of at least 32, which this transistor can do.  The other transistors are only handling the current for individual LEDs, which is 20 mA, so don't need as much base drive.  That is why R2-R5 can be larger than R1.
R6-R9 are sized so that after a little voltage drop in the anode and cathode transistors, about 20 mA should flow thru the LEDs if they are normal green ones.  Red LEDs have a little lower voltage drop, so you may need a little higher series resistor.
Comment: @Dean: Yes, by convention a bar indicates negative logic.  In that case that means the line must be low to enable the common side of the LEDs.  I could have named it COMMON_DISABLE and left off the bar.
Comment: Perfect! Exactly what I was looking for, part numbers, values and all. Thanks!
Comment: In your answer you have a bar over the COMMON_ENABLED, are you saying to enable the LEDs the COMMON_ENABLED but be low?
Answer: Kind of hard to tell what you're looking for from your question... do you have an array of LEDs?
This is the basic schematic for using a PNP transistor to power an LED from a microcontroller pin.

The idea is that the microcontroller only has to provide the control signal on the base of the transistor while the main draw comes from the power supply (the +V in the schematic above) through the transistor.
As far as calculating values for the resistors, it depends on so many variables you didn't give us including but not limited to: forward-bias voltage drop of your LED (Vf) and the recommended on current of the LED (Id). Please provide more information about your setup so we can answer your question better.
You might also want to research multiplexing and charlieplexing to see if they would help with your project. They allow lower power draw and less pin usage on your microcontroller for large displays.
Comment: Yes, it's an array of LED's in parallel, with a common anode. 16 segment LED display, each segment with ~20mA forward current each, 2.0V forward voltage drop. I've multiplexed each display digit together, however the common anode restricts my options, and leads to this problem - all 16 segments have to be sourced from one micro pin. Thank you for the schematic :) given the new info, can anyone suggest a value / part # for the transistor? Thanks!
Answer: Instead of JGord's answer I would go for a NPN transistor instead. This way, a high input on the base (the middle one) will open up for collector-emitter current and the schematic would be the same.
You could buy almost any transistor you want. These ones will suffice, just be sure the collector current is able to drive at least 400mA.
Comment: do you decided to use a NPN to be placed as a emitter follower circuit?
Comment: Problem is, they need to be connected between the common anode of the led and the positive rail, would an NPN still work there?
Comment: Yes, doesn't matter on what side it is placed, you only want current to flow


How to show album title for 'album with no photos' in view

Question: I am using node gallery module to create albums and upload photos. I have created a view to create albums and upload photos.It is working fine.But when i create album with no photos, album title is not getting displayed.I want to show 'default image and title of the album' for 'albums with no photos'.I have specified 'title and default image' in 'content:photo' no result behaviour in my view and Only the node author can see this but other users are not able to view this album. How to do this?
Answer: One of two ways:
1) Create a Header. Under Header (middle of page) create a Global Text. This will create a title for the View regardless of it's contents
2) Under Advanced, create a NO RESULTS BEHAVIOUR. This functions on the view as a whole, so that if there is not content to display at all, this will be displayed
Answer: You also seem to have a permission issue. Maybe some of your nodes aren't published. Check that first. If you are unsure set your views'Query settings' to 'Disable SQL rewriting' and see if it works. If it does then it is definitely a permission issue which you need to track down. It is not advisable unless you are doing it by design to leave Disable SQL rewriting on. And if you are using the file entity then also check the permission there.
Comment: I set the 'Disable sql rewriting' in views query setting and its working fine.Thanks!


Password expiration policies

Question: Having just received an email from a supplier informing us that they would be forcing us to change our password every six months, I'm curious to see what password expiration policies people use and why they use them.
Comment: Some of the ideas/links here may help http://serverfault.com/questions/4221/user-password-age-complexity-policy
Answer: I would suggest employing a bit of math that takes into account your minimum password complexity, how fast an attacker could guess passwords, the number of unlocked accounts you have, and some informed information about your risks.
Hopefully you have some sort of rate-limiting for password guessing. Typically that would be via something that temporary locks accounts after some number of bad passwords.
And hopefully you have some sort of password-complexity requirements so that "A" and "password" aren't allowed.
Let's assume that after 30 password failures in 10 minutes you will lock an account for 20 minutes. That effectively limits the password guess rate to 174 per hour, or 4176 per day.  But let's assume it's per user.
Let's assume you require 8+ character passwords containing upper, lower and a number, and that you do some dictionary checks to ensure that those passwords are reasonably random.   Worst case your users all put the one upper, and one number in the same place and your attacker knows it, so you've got 10 * 26 ^ 7 (80G) possible passwords.  Best case is 62^8 (218T).
So, an attacker trying every possible password would hit them all within 50,000 years in the worst case, and almost 600 million millenia in the best case.  Or, to put it another way, given one year they'd have between 1 in 50,000 and 1 in 52,000,000,000 of guessing.  If you have a userbase of 50,000 it's almost guaranteed that in the worst case they'd get into one account per year and have roughly a 50% chance of getting one account every 6 months.
And if you had no rate limiting and an attacker could guess a billion passwords a day?  A one in 600 chance of getting into an account in a year, or a virtual guarantee of getting about 80 out of your 50,000 users every year.
Work on that math, and figure out where your acceptable risk level is.  And remember that the shorter you set it, the harder it will be for users to remember and the more likely they'll have it written down someplace convenient for an on-site attacker.
As an added bonus: if somebody is trying thousands of passwords per user per day against your systems, I really hope you have some sort of monitoring that would pick that up.
EDIT:
Forgot to mention: our actual policy is 90 days, but that has everything to do with findings by misguided security auditors and nothing to do with reality.
Comment: +1 for actual calculations. This is a fat better answer than the accepted one.
Answer: There is a fine line here between never changing it and changing it too often. Having the same passwords for years is often not a good solution, especially if it's publicly available. But forcing a rigid policy of changing it too often also has bad side effects. One place I worked at, forced all users on the internal network to change passwords every 6th week and the passowrd couldn't be the same as the six previous passwords. Three wrong passwords locked the workstation, and the IT staff had to unlock it. Which resulted in everyone writing the password on Post-It notes hanging on the screen or placed in their drawer. Nightmare.
I'd say changing the password once every 6 months should be sufficient. This will avoid those dreaded Post-It notes.
Comment: Sorry, but this is a stupid answer. On what are you basing your 6 months? If someone gets your password hashes, then unless you have a quite strong password (which is, in general, unlikely, **especially** if you're having to change it regularly), then they can brute force it offline, and they'll have your password in a matter of days, not weeks or months. Having good temporary lockout mechanisms on your front-ends will prevent brute force from that angle, and if your password hashes ARE compromised, then just expire all the passwords then.
Answer: 90 days seems to be sufficient for most scenarios. My biggest concern is password complexity. More than the time frame issue in generating post-it notes is the forced complexity. It's one thing to avoid dictionary words and another to have special characters, but when you start saying that no characters can repeat or be in ascending/descending order, you have made your users lives difficult. Add that to a short password life and you've just welcomed in more issues.
Answer: Password expiration is annoying and reduces security.
Password expiration defends against the situation where an attacker has compromised a user's password once already, but does not have a mechanism of finding out what it is on an ongoing basis (e.g. keylogger)
However, it also makes it harder to remember passwords, making it more likely that users will write them down.
As defending against an already-compromised password is not really necessary (you hope), I consider password expiration useless.
Get users to choose a strong password to begin with; encourage them to remember it, then don't require them to change it, ever, or they will end up writing them down everywhere.
Answer: If you have a device that needs "high to ultra-high" security guarantees, you are better off using a hardware token that generates one-time passwords instead of relying on having password expirations.
The main "win" for a password expiry system is that you WILL, eventually, have an account disabled if the account-holder leaves the organisation, as an extra "check and balance" to "the account should be disabled when the account-holder leaves".
Enforcing password expiration leads, at best, to high-quality passwords written down and in the worst case to bad passwords (at a previous workplace, once we were forced to use password expiration, I ended up using (essentially) prefixJan2003, prefixFeb2003 and so on, as my preferred method of generating passwords (48 random bits, Base64-encoded) doesn't scale to "new passwords every month").
Answer: I think if you ask 10 different security professionals this question - you would get 10 different answers.
This greatly depends on how critical the asset the password is protecting.
If you have a highly secure asset, you need to set your password expiration policy short enough so that any outside intruder will not have time to brute force a password. Another variable in this situation is what level of complexity is required on the passwords.
For low to medium security systems I think a 6 month expiration policy is very fair.
For high level security I think a month would be better - and for 'ultra' secure installations even shorter time periods would be expected.
Comment: This doesn't make much sense — given a secure (random) password of reasonable length, in what reasonable scenario would that password be brute-forcible in 6 months, but not one? If its an online attack, why did your monitoring not notice billions of failed logins; if its an offline attack, they could just get 6x more computing power.
Comment: This makes plenty sense. If an attacker gets the encrypted password file, they have that much more time to run the attack (assuming an offline attack). And as you would say, they would need 6x the hardware - which is not trivial especially if it is a 'casual' attacker and not someone hell-bent on cracking the passwords at any cost, which I do not think is the typical situation in a low-to-medium security system.
Answer: We enforce a 90-day password expiry on everyone here, (including ourselves.)
Mostly because it's simply best-practices. Chances of someone using a "weak" password, vs. a stronger one is greater and the longer you leave it the same would possibly result in a long-term, undetected security breach.
Comment: This is a research interest of mine. I believe security is as much about user education and psychology as much as technical requirements for security. The most secure installation can be undermined by unsafe practices for the end-user or even administrators!
Comment: But does forcing a non-technical user to change their password frequently improve security or lower it, by making the user write their current password down? I'd be interested in discussions on that subject.
Comment: One tact taken at our home office by our most senior infrastructure guy was to suggest the use of funny sentences for passwords for the non-tech oriented folks. I think his example was "IHateHavingToResetMyPasswordEvery45Days" which is certainly easy to remember.
Comment: You may want to advise them that if they DO write it down, they should (a) not write it down along with the username, company, etc.; (b) carry it with them, in e.g., their wallet or purse, (c) maybe print out an entire small sheet of random passwords, and remember only which one it is. In fact, I'd guess that if your users did (a) through (c), they could then use completely random 10+ character passwords, and overall security would be improved vs. not writing the passwords down.
Comment: On site at my current client, walking past the non-technical workers' desks reveals post-it note upon post-it note of passwords. This is in a 90-day environment. The complexity requirements are minimal: 8 char or longer, mixed alpha-numeric. I shudder every time I see florescent colored paper near a monitor now.
Comment: ddrager; I *wholeheartedly* agree, that it's VERY much about user education and psychology. Leading someone down a thorny path is a lot easier if you exercise patience, understanding and teach them where and how to step. :)
Comment: We also strongly advise against users writing them down, but in the end that's all someone can do.. Is advise.

If they write it down in an easily findable spot, surely it lowers the value. That being said..

I believe that what it all really boils down to is education and effort on the password enforcer's part to illustrate how "strong" passwords can be remembered quite easily by using mnemonic methods.
Comment: Rob; A funny story to relate - I took a tour of a BT satellite communications facility many years ago and noticed little taped pieces of paper on each monitor. I asked the tour guide what that was and he took a look, turned red and said, "Err, well, they appear to be passwords to the system." :)
Comment: Rob; Dude, I'm _totally_ going to use that, (credited of course :)
Answer: We expire passwords yearly and require strong (preferably random) passwords longer than 10 characters. We run dictionary attacks on people's passwords when they change them. We keep past password hashes so that passwords can't be re-used. We also check for potential dates in the password like vatine said. ;) The last was my addition...
At a former job, we did try expiring more frequently at a new network security administrator's behest -- every two months. Two weeks after the first forced change, I took him around our administrative offices and we looked under people's keyboards and mousepads. Over 50% of them had a password written on a post-it underneath. He was happy to loosen the policy after we sat down and talked to the administrative staff -- their opinion was that they didn't have it long enough to memorize.
Most of our stuff these days is single sign-on within a few silos. Campus resources (rarely used for most people) are in one silo and that password is managed by our central IT group. Departmental resources (used daily -- machine login, email, website editing, photocopier) is a password managed by our group, also expired yearly. If people gripe about being frustrated, we point out that they really only have one password to remember.
These days, I generate an md5sum on a random file in /var/log and use a subset of that for my passwords.
Answer: We had a lot of discussions about this a couple years ago when we started a password expiration policy. We had just finished a l0phcract run with rainbow tables against the AD tree to see just how bad it was, and it was pretty horrific. An eye-bleeding number of users still used their "helpdesk temp" password after calling in/dropping by for a password reset, something horrendous like 30% used "password" or some variant as their password (p@$$w0rd, etc). That convinced management that this needed to happen.
Being higher ed, we had summer to contend with when selecting an interval. A lot of our faculty don't teach during the summer, so our helpdesk had to brace for the, "I forgot my password" calls as they all come back in September. I think, and I may be wrong, that our interval is 6 months with a summer-quarter exception. So if your 6mo password expiration has it expiring in mid-august, it would be randomly reprogrammed to reset in late Sept to early Oct.
A better question is how often your utility account and admin passwords get rotated. All too often those seem to get exempted from password change policies. Who wants to go through all those scripts for a utility account password change? And some backup systems make it hard to change used-passwords, which provides a disincentive to change admin passwords.
Comment: How does password expiration help with poor password quality? (Though I could certainly see setting helpdesk reset passwords as expire-at-next-login. Or just have the helpdesk generate random passwords)
Comment: Our password change process also include quality checks. So, it doesn't help directly, but when used in conjunction with quality checks they both increase attack resilience.
Answer: One major problem with expiring password frequently is that people will struggle to remember them, so you'll either have people using weak or similar passwords, or if your policy doesn't allow this, they will start writing down the passwords to help remember them. You'll also have more password change requests, when people do forget them.
Personally, it depends on what the password is used for, but I tend not to keep a password more than 3 months, unless it's a complete throwaway account. For higher risk stuff, every month or so is good, and defiantly change it if someone else who knows it leaves. Because I work in a small computer support business, we have multiple passwords that are shared between lots of people, so we don't want to change them very often, because of the disruption it can cause.
Answer: I think that having a more secure password is much more important than frequently changing it, but both are definitely necessary for a secure system.
The argument goes that complex passwords are difficult to remember, and lead to employees writing them down.  My belief on this is that the vast majority of the attacks come from the outside, and even writing down a complex password and taping it to your monitor is more secure than having a simple password memorized.
Comment: Actually, the vast majority of attacks in our workplace come from students breaking into offices in an attempt to access tests or to change grades.

In previous (non-academic) positions, the vast majority of attacks came from social engineering.
Comment: Most users have their names on a nameplate outside of their offices. Finding the corporate standard in usernames isn't so hard - then matching the nameplate on the door to the password under the keyboard becomes trivial.  Also, you should be wary of admins who put their passwords under their keyboard....
Answer: Interesting comments so far.  Of course why is it always the debated that remembering passwords is an technical versus non-technical personnel issue in a company?  What does someone's ability with computer hardware/software have anything to do with their ability to take security serious?  Will a non-technical person give out their Credit Card or Debit Pins #?  Also, people placing passwords on post-it notes on their desk should be grounds for dismissal.  Its amazing how people's memory will improve when they actually realize security is important and must be taken seriously.  I see it no different that the role of dress codes and conduct policies at work.  Follow the rules or goodbye!
Answer: I'm implementing one-time pad and time-token based authentication, so, in theory, every time the user logs in.
Though this is arguably off-topic, a one-time pad seems to be a superior solution.
Similarly, and more basically, ensuring that the user creates a strong password, and understands the ethic behind your security policy (don't write it down, don't make it your birthday, don't give it to anyone) will go much farther than simply forcing them to change it every nth time-based interval.

Password expiration policies


Orthorectifying or Georeferencing aerial photographs

Question: I got 3 aerial photographs from a mountainous area (~3500 - 4000 m.a.s.l), from 1956, 1965, 1977 (no metadata, no camera parameters, scanned white and black). My study catchment is relatively small (1 sq. km) and I would like to use those photos in order to assess potential vegetation changes. I know both the processes of orthorectification and georeferencing, however, I am not sure about which process should be used in this case. For orthorectifying I will require additional information, particularly the detailed DEM, which is very difficult to get for this area, while for georeferencing I will need some control points, a-priori the georeferencing process is 'easier' however I am not sure how comparable the results can be, with respect to orthorectification, and also in terms of overall accuracy assessment. Since the area of interest, is relatively small (each photography, covers approximately 10x10 km), I would not expect severe deformations, yet the area surface is very irregular.  Any reference or previous experience in this regard is welcome.
Comment: You didn't say which specific software you want to use ?
Comment: I know the processes in several softwares (MiraMon, QGIS, ArcMap, ENVI, ERDAS), currently I would prefer free-software options, for licensing, but in this case I need more a justification for methodology use.
Comment: Have you looked into Agisoft Metashape ? https://www.agisoft.com/   I work a lot of old 1930's aerial photos and it does a nice job .
Answer: It's hard to answer this question without seeing the images, but I'll try. For orthorectification, you need to know internal orientation, deduced from the camera, and external orientation parameters. Forget about this variant in your case.
If your mountainous area contains remarkable reference points (such as road crossings, free-standing trees, big detached stones, some human-made objects), you can georeference all three images to these points. Use base maps, such as Google or Bing, as a background. Open-source QGIS, with its default Georeferencer plugin, is suitable for this job. You may need to experiment with various transformation types, before getting a decent result.
What I would do is to:

Add some web base map to QGIS. You can do it with the help of
QuickMapServices plugin, which allows you to select from a big
list of data providers. Or, perhaps, you have your topographic maps
for it.
Georeference the first aerial image to the base map. At this
stage, you may spend much time selecting an appropriate
transformation type. E.g., I would try Thin Plate Spline
transformation and a lot of georeferencing points along the borders
of the aerial image and inside it.
Georeference the second aerial image to the first one. As the transformation
type is already defined, it should go much faster now.
Georeference the third image to the first one.

Doing 3 and 4 allows you to check RMSE of your georeferencing points against the first aerophotograph. But be careful: usually, spline transformations give an RMS error of around zero; however, this does not mean that the image is precisely aligned in space.
The planar accuracy of your final georeferenced maps can be estimated only when you have ground control points visible on all aerophotographs, and you know their accurate coordinates.
P.S. Please, check out this QGIS Georeferencer tutorial.
P.P.S. I used QGIS Georeferencer to align scanned black-and-white images from American reconnaissance satellites CORONA with modern satellite images. It worked well, but it required a big amount of reference points, which was hard to achieve, considering the territory change over 50 years.
Comment: These area is complex indeed, since no recognizable features are easy to locate, in addition, the available imagery for the area is very coarse in resolution. I have previously tried with the QGIS plugin (with several methods), and I obtained relatively good results when compared with a more recent orthophoto. However I was suggested to orthorectify the images instead of simply georeference them, and that is why I was looking for options. Thanks for your suggestion.
Comment: Yes it is not easy doing it in QGIS but you would need a 3D Photogrammetry software like Agisoft Metashape, Pix4D, etc ... you can identify rocks, roads, buildings if they existed back then and today....


Does the principal quantum number, $n$, have an operator?

Question: The hydrogen energy eigenstates are labelled with well-defined $n$, the principal quantum number. Is there an associated operator than one can apply to these wavefunctions which would result in an eigenvalue of $n$ multiplied by the hydrogen wavefunction? If so, what does the operator look like?
Answer: You can always construct an operator that gives you any quantum number you wish, using the eigenstates. Let the bound states of the hydrogen atom be $|n,l,m\rangle$; the representations of these states in position space (that is, the spatial wave functions) are well known. Then you may have an operator
$${\cal N}=\sum_{n=1}^{\infty}\sum_{l=0}^{n-1}\sum_{m=-l}^{l}n|n,l,m\rangle\langle n,l,m|,$$
for which the eigenvalues are the principal quantum numbers for the bound states and zero otherwise.
In the position space representation of this operator, each term in the sum involves the explicit Schrödinger wave function. For example, when the $n=1$ term acts on a general wave function $\Psi(\vec{r})$, it takes the form
$$\psi_{1,0,0}(\vec{r})\int d^{3}r'\,\psi^{\dagger}_{1,0,0}\left(\vec{r}\,'\right)\Psi\left(\vec{r}\,'\right)
=\frac{1}{\pi a_{0}^{3}}\exp\left(-r/a_{0}\right)\int d^{3}r'\,
\exp\left(-r'/a_{0}\right)\Psi\left(\vec{r}\,'\right).$$
You could also write this operator in a different basis of energy eigenstates (such as that obtained by solving the Coulomb problem in parabolic coordinates).
However, if you asking whether this has a convenient form when expressed in terms of $\vec{r}$ and $\vec{p}$, the answer is no. For one thing, the principal quantum number is not something that is even defined for the complete hydrogen spectrum; the continuum states above zero energy do not have a value for $n$, and if you tried to continue $n$ to these unbound states, its values would be imaginary. If you apply the explicit operator ${\cal N}$ to a continuum energy eigenstate, you will get $0$, since the bound states and continuum states are orthogonal.
Answer: The principal quantum number $n$ corresponds to the energy of the state $|n\ell m\rangle$. In other words, the operator associated to $n$ is the Hamiltonian $H$, and, for the hydrogen atom,
$$ H|n\ell m\rangle = E_n|n\ell m\rangle,$$
where $E_n = -E_I / n^2$, and $E_I$ is the ionization energy of the hydrogen atom.


how to create a duplicate data extension from a synchronized DE without manually typing all fields for the new DE

Question: I'm trying to create a new DE from an existing synchronized DE with all the fields prepopulated. When I create the DE I want it to copy all the fields and field types for the synchronized DE to the new DE without me having to either manually typing them or using the SOAP API.
I tried creating a filter from the synchronized DE but that will not solve my issue. I need it to be specifically a "standard" DE rather than a filter.
Is this by any chance possible at this moment?
Answer: If you are not willing to type it manually or use SOAP API, there is another way to go: using Deployment Manager.

Use Deployment Manager to copy the design of a journey or data
  extension and deploy it to other Marketing Cloud business units or
  enterprises. You can then configure the new draft journey or data
  extension design in the target account. Deployment Manager doesn't
  store or migrate any customer or campaign data.

Steps to follow:
1- Install the Deployment Manager on your BU --> Help
2- Create a Snapshot of your DE and download it --> Help
3- Deploy the Snapshot on the same BU --> Help
I've tested creating a Filtred DE, create a Snapshot and deploy it. It actually deploys a Standard DE instead of filtered DE which responds to your use case.
Hope this helps
Comment: Good find using deployment manager
Comment: @rachidmamai I don't see an option to select from Synchronized Data Extensions under component types. I only see "Journeys", "Data Extensions", 'Shared Data Extensions
Comment: Thanks EasyE. @NinoY You can use your filtered DE created from your Synchronized DE and then create a Snapshot > Deploy the filtered DE..
Comment: @RachidMamai seems like its a bit glitchy. We have a lot of DEs so I have to search for the new one and it seems like the search bar doesnt work or something. unfortunately, I wasn't able to achieve my goal with it.


Any way to see an Active Directory password?

Question: Before you jump to conclusions, let me explain. We have a password reset tool that is not working. For some reason when you use it, it resets your password to some unknown value (Not what you changed it to, or what it was before). I have setup a test "user" in the appropriate OU, and I want to be able to see what the reset tool is changing the password to. That way maybe I can maybe understand what's going on. Any help would be greatly appreciated.
Comment: What is the password reset tool? Why not just reset the password to a known value and have the user change their password at next login?
Comment: I'd like to know what this tool is because how is it changing the password to anything other than what it was, if it isn't using Administrator or that user's access tokens with permissions to do so?...
Answer: AD passwords (just like Windows ones) are stored using non-reversible encryption, so the standard answer is a definite "NO".
There is a GPO settings that will tell AD (or any Windows system) to store passwords using reversible encryption, but there is no built-in tool to decrypt them (although there is some documentation floating around on how to do that). Of course, this is exactly as insecure as it looks.
Answer: If you need to see the plain text of what it's setting it to, and you can't get the reset tool to spit that info out itself, then you have two options: enabling reversible encryption, or using a password filter.
With reversible encryption, you can get at the original password, but it's not a pleasant process.
With a password filter, you can dump out all password changes to text, but that's obviously not a good thing for security when it comes to your non-test users.
If you only need to see the hash to see if it was set correctly, though, then you can dump the hash database and compare.
Comment: **Not pleasant process**, very _harder_ in C# IMHO. Not samples in github about it.
Answer: No.  The Password attribute is "write-only".  There is no mechanism exposed to provide reading of this attribute.
More information:
User-Password Attribute
http://msdn.microsoft.com/en-us/library/ms680851%28v=vs.85%29.aspx
Comment: That's the hash, anyway, which doesn't do a lot of good regarding this question, but you can certainly get at it through unsupported means.  As I mentioned in my answer, password filters are an official, supported way to get copies of the plain passwords as they change.  It's downhill from there with reversible encryption and attacks against hashes, but an unqualified "no" based on the ldap attribute is a bit.. narrow.


Is my reputation on meta linked to the site?

Question: I noticed that my reputation on Salesforce meta is the same as the one on the actual site. On Stackoverflow I have seperate reputation on meta and on the site. Is this because this is still in beta? My badges are not "copied".
Answer: Check out the FAQ for the meta site.

What is reputation?
You must have at least 5 reputation on the main website to participate on Salesforce Meta - Stack Exchange.
Reputation here is entirely derived from the main website; your reputation is the same here as it is there, synchronized hourly. Votes here do not affect your reputation in any way. However, you can earn unique badges here on the meta site.
(Please note that offensive penalties, if levied by the community through spam or offensive votes on your posts here, will affect your reputation on the main website.)
Amass enough reputation points on the main site and Salesforce - Stack Exchange will allow you to do more things:

15 - Vote up
15 - Flag for moderator attention
50 - Leave comments†
100 - Edit community wiki posts
125 - Vote down
150 - Create new tags
200 - Reduced advertising
200 - Retag questions
250 - Vote to close, reopen, or migrate your questions
500 - Vote to close, reopen, or migrate any questions
750 - Show total up and down vote counts
1000 - Edit other people's posts
2000 - Delete closed questions, access to moderation tools

† you can always comment on your questions and answers, and any answers to questions you've asked, even with 1 rep.
At the high end of this reputation spectrum there is little difference between users with high reputation and ♦ moderators. That is very much intentional. We don't run Salesforce - Stack Exchange. The community does.
Comment: You can track privileges and learn more about each one here: http://salesforce.stackexchange.com/privileges
Comment: Right, thanks. I did skip through the FAQ, but I must've missed it...


It is ethical and common that a professor ask the student to write their own recommendation letter?

Question: I am in a unique situation. My supervisor and two other professors I approached for recommendation letter have asked me to write the my own recommendation letter and they will sign it.
Is it ethical and common practice?
How can I handle this situation? I already requested three of them multiple times, but always received same response that they are busy and will sign the letter which I sent them.
Comment: I see no ethical conflicts, this is not uncommon practice in my experience.
Comment: I have had a referee ask me to provide a list of accomplishments, qualities and skills that I would like them to mention. (Note: I'm an engineering researcher). It can be a real help to the referee because even though they know you personally they aren't necessarily able to name a bunch of your accomplishments off the top of their head. Maybe you could provide your referees with such a summary instead of a completely written letter and ask them to write about your accomplishments, etc. in their own words.
Comment: Did you ever mention to them, that everyone else also asked you to write the letter yourselves and that you would prefer not to hand in three letters by the same person? Maybe they are all choosing the "easy way out", but this can really go bad for you. One self-written letter might be okay (though not optimal), but all of them?
Comment: I believe that the professor does it as a gift to you, a complement about the esteem in which you are held -- she or he allows you to focus on specific aspects of your character, skills, or expertise ... since two professors give you this opportunity you should exploit it to produce complementary letters for the committee.
Comment: This practice will vary widely by field. Perhaps you could state a broad field in your question. For instance, I have been told that in the medical fields, applicants are almost always asked to draft their letters. In my social sciences field, I was only asked to provide bullet points on several topics by my committee.
Answer: It's not common (in my experience).  I have requested letters of recommendation from professors in a couple of different fields, and was never asked to write my own.  Nor have I heard of anyone who was asked to.  That said, it might be something that varies by field, institution, culture, etc.  I wouldn't rule out it being common in some contexts--I just don't know of any.
It's not unethical. There is not an ethical requirement that a letter from a person was actually written by that person.  Even though I've never heard of a student being asked to write their own letter, it is well known that, often, professors don't actually write the letters themselves.  Secretarial staff often do much of the actual writing (hopefully with the professor giving input about the student's strong points, things to emphasize, etc).  In a broader professional context, it's quite common for people to sign the name at the bottom of letters that were not written by them, for a variety of purposes.
Who wrote the letter, ultimately, doesn't matter.  What does matter is that the person signing their name at the bottom agrees with all the content and is willing to stand behind it.  As long as your adviser is happy to agree with what you said, there is no ethical problem here.
That said, it's not ideal, either.  I would argue that a professor who asks you to write your own letter is not doing a great job discharging their academic responsibilities.  Really the content of the letter ought to come from them, even if someone else is writing it up.  This is an opportunity for them to assist you in your career, and they aren't really taking that opportunity seriously.  In addition, it puts you in a rather awkward situation--many people would not be comfortable putting complimentary words about themselves in someone else's mouth.
So, I sympathize with your situation, it's not great.  But you probably don't have a good alternative other than writing the letter as requested, at least from your supervisor.  You want a recommendation from your supervisor, and substituting someone else wouldn't be equivalent.  At least you get to make sure it says what you want!  Just make sure you get someone (who is actually interested in helping you) to review it, both for content and to catch any errors.
Comment: @dan1111 I have to respectfully disagree. I'm not sure it IS ethical, and in my experience, it is fairly common, moreso for undergraduates. Ethically speaking, writing your own rec letter weakens its credibility in a way that helps no parties. The student is not critiqued properly, the recommender hasn't fulfilled his or her duty, and the receiving party receives a questionable review, not to mention the fact it can't be confidential. I'd say it is ethically questionable.
Comment: I can write a letter of recommendation for someone else but writing my own is really tough especially three different letters about me by myself. moreover I am not experience to know what is the best way to write a recommendation letter.
Comment: @MBK, yes, I agree that you are being put in a difficult situation here.  I think the first step would be looking for example letters.  Also if there is anyone who has some experience who is willing to help you, that would be a good thing.
Comment: I have been told this practice varies widely by field. You might specify your broad field in your answer.
Comment: Oh, I now see that you have made a reference to this variation.
Comment: I was asked to write my own rec letter by two professors, one in engineering and one in global health.
Answer: When I asked an old professor for a letter of recommendation for grad school, she had me write the letter and send it to her to use. I don't know how much she changed, if any.
The reason given was that she wanted to know what I wanted her to write about me and what to focus on. I had a reasonably close relationship with her as I was a TA for her for a semester.
It can be difficult to write the letter about yourself, but as long as you're honest, talk yourself up! Take this as an opportunity to highlight what you do want this letter to highlight about you.
@Dawn mentioned in a comment that this may be field specific, this experience was for an MBA program.


Internet sharing between Windows 7 and Windows Mobile 6.1

Question: I have Samsung phone running Windows Mobile 6.1 and a laptop running Windows 7 with a USB Modem to access the internet and I would like to share the internet between my laptop and my phone. I tried to make Ad Hoc network and I successfully connected to the Ad Hoc network but unfortunately I can't browse the internet or access MSN Messenger on my phone. Does anyone here have an idea as to how I can connect my phone to the internet via my laptop?
Answer: If your PC and phone are bluetooth enabled then you can do this by:

Plug the phone into the computer via USB, Windows Mobile Device Center should install (if not then you can download it from: http://www.microsoft.com/download/en/details.aspx?id=14) once it is installed set up a sync connection. (you can sync whatever you want)
Connect your phone to your computer via Bluetooth
On your PC go to your Bluetooth settings (just search in the start menu) and go under the COM Ports tab, click "Add..." and select "Incoming" then click okay (note which port was just created) and then okay again on the first dialog.
On your PC go to the Windows Mobile Device Center click Mobile Device Settings then Connection settings (it may take a minute to show the dialog box) select all of the checkboxes, then under "Allow connections to one of the following" select the COM port that you assigned in the last step then select that the computer is connected to the internet.
Go to your phone under sync settings there should be a check box labeled "Allow advanced network functionality" check it.

Test the network connection on your phone if it is working disconnect the USB cable and then test it again (make sure that you are connected to the computer via Bluetooth).
The downside is that every time you want to connect to the internet you have to connect via Bluetooth and you have to be in range and sometimes you even have to tell the phone to sync immediately!
Comment: thanx for editing my post. Sorry about my english. Regarding to your answer: When I connected my phone to the PC the OS assigned the port number 26 as incoming Bluetooth data, and this port doesn't appear in the Connection settings (there was an option called Bluetooth and I chose it), also I tried to find `Allow advanced network functionality` and can't see it! My phone is `Samsung Omnia
Windows Mobile 6.1
GT-B7320` which is non-tuched device!.
Comment: No problem with your english, it's just that I had the same problem and could not find an answer anywhere so I changed it a bit so that it will show up in more searches for other people.

 After a COM port is automatically assigned you need to assign ANOTHER one as per the instructions above and then you will be able to select it.

It should be in your sync settings under advanced.
Answer: In Windows 7, you can bridge your wi-fi and ethernet connections.

Open the Network and Sharing Center.
Press Change adapter settings.
Hold Ctrl and click the Local Area Connection and the Wireless Network Connection.
Right-click one of the selected entries and select Bridge Connections.

Now anything connected on your wireless connection is essentially on the same network as your ethernet connection.  Realise this is a two-way street so take any usual security precautions.
Comment: But my USB Modem shows different netowrk connection than Wireless Connection.
Comment: Sorry, I made an assumption your laptop was connected to the internet by a cable, which I see now was stated as otherwise in your question.  Bridge the *Wireless Network Connection* and the *USB Modem* instead.  Then you can connect the phone to the laptop by wi-fi and it should utilise the laptop's USB Modem.
Comment: By this way I can't see Bridge option! It does not appear!
Comment: Bugger.  The USB Modem driver might not support this method.  :-(


Has any election to a national legislature had no candidate stand?

Question: In the recent local elections in the UK one community in Wales had no candidate stand for election to the Powys council. It appears to be not uncommon for House races in the United States to be uncontested, but are there any examples of an election to a national legislature where no candidate ran?
Comment: Do you mean in any country on the planet, or just in the US?
Comment: The closest example I can think of is that sometimes in an uncontested race, the sole candidate dies or drops out when it is too late for anyone else to run procedurally, leading to a vacancy. At the local level it happens fairly often in small rural governments and a consistent failure to get people to run for office is the main criteria in Colorado for dissolving a governmental entity. Where write in votes are allowed you just need one person to vote for himself to prevent this from happening.
Answer: In the parliamentary elections in Tunisa held in December 2022, several seats had no candidate stand in them. Reuters:

Under the new constitution drafted by [President] Saied and approved
by a referendum last July, the new parliament will have very limited
powers.
With the main parties absent, a total of 1,058 candidates - only 120
of them women - were running for 161 seats.
For 10 of those - seven in Tunisia and three decided by expatriate
voters - there is just one candidate. A further seven of the seats
decided by expatriate voters have no candidates running at all.
The election was part of a series of political changes made by Saied
after he shut down the previous parliament last year, in moves his
critics have called a coup.
After the turnout figures were announced, major parties, among them
the Salvation Front, which includes the Islamist Ennahda party and its
arch-rival, the Free Constitutional Party, said Saied had no
legitimacy and should step down, calling for massive protests.
Answer: In Algeria currently this problem exists in a way. The previous President who has reigned for many terms and is seen as being controlled by wealthy people and the military has finally stepped down from running for a 5th term as a result of huge protests. The problem is that no serious opposition parties or candidates exist because of years of political stiffling and suppression, that was the one excuse the group used to justify an attempt at a 5th term.
Comment: Can you include any specific seats that had zero candidates in fact? Or is this just a general wave that some seats had fewer candidates than desired and some candidates were worse than desired?


How can the antiparticle of Hawking radiation fall into the black hole?

Question: According to the theory, when quantum fluctuations occur near the event horizon, one is absorbed and the other is emitted as hawking radiation
But in order to conserve the energy the fallen particle must've been of negative mass
We know that negative mass particles move in the opposite direction of the acceleration applied to it, so how can that negative mass particle fall into the black hole in the first place?
Answer: The description of Hawking radiation as a particle - antiparticle pair being produced near the horizon is not entirely accurate.
It may be better to think of it in terms of the Unruh effect, which states that an accelerated observer will see blackbody radiation where an unaccelerated one will see nothing. Near the horizon, an observer must accelerate to keep from falling in. Thus they will see a thermal bath of particles that arise from the horizon and fall back in. However, we also require local thermal equilibrium. Therefore some of this particles must escape to infinity.
This answer may prove useful for you. It is better to not think in terms of mass flux and rather energy flux. There is a positive energy flux to infinity, so there must be a negative energy flux (relative to the exterior) that falls into the black hole. This leads to evaporation and the usual consequences of Hawking radiation.
Answer: This is a wrong statement:

But in order to conserve the energy the fallen particle must've been of negative mass

Real particle pairs  have real masses, for example an electron positron pair each particle will have a mass of about .5 MeV. The energy for the masses  creation + kinetic energy is provided by the gravitational energy of the black hole. That is why one says that black holes "evaporate". They lose gravitational energy by Hawking radiation.


Why did Michelson believe the aether was moving?

Question: If a wave moves east towards California the wave-motion would be slower north-south. Is this the kind of way they were thinking about the aether as medium for light, of what was later, by Lorentz, styled a "dilation" (in the north-south motion)?
Answer:
Why did Michelson believe the aether was moving?

He didn't, he believed the Earth was moving. And the Sun, and maybe other things.
In contrast, it was already understood that the aether was "universal", not necessarily moving or not moving on it's own, but whatever motion it had, it had to be the same motion everywhere.
Why? Well let's say the aether was moving north on one half of the universe and south on the other; in this case the light from different parts of the sky would have different frequencies due to the Doppler effect. And they definitely weren't seeing that, quite the opposite, the frequencies were so constant that they were already used to determine the chemical makeup of different stars through spectroscopy.
So if the aether is universal, then we have a great yardstick. It doesn't really matter if it's moving or now, we can just express our velocity in those terms, which is the whole idea of the Galilean transformation - speeds are relative. And since it's universal, we can use that to compare motion of different bodies.
Now of course the easiest one to start with is the Earth, because that's where we keep all our stuff. And we're pretty sure the Earth is orbiting around the Sun, just as sure as we are that the aether isn't orbiting around the Sun. So there should be a relative velocity between the Earth and aether, it should vary depending on the time of day, and the exact magnitude should vary by season.
And yet none of this happened. So then things got complicated. If the Earth isn't moving compared to the aether, then what...

the Earth just isn't moving
the aether is dragged around by the Earth
the aether doesn't exist

Option 1 was eliminated immediately, we're not that special. Option 2 resulted in lots of new work, but it all ultimately failed. And so... option 3.
Comment: 4. the aether distorts the dimensions of the experimental apparatus
Comment: With option 2 as I understood correctly Aether being dragged around by celestial bodies would result in light waves being produced by orbital motion correct as different regions of aether crashed together? And that definitely doesn't occur.
Answer: Michelson and most physicists of the time thought that the (A)ether was moving relative to the Earth, or, amounting to the same thing, that the Earth was moving relative to the Ether. They had taken on board, from Copernicus, Galileo and their successors, that it was better to think of the Earth moving round the Sun, and not the other way about. So if the Ether was a universal medium permeating the solar system and beyond, it was natural to think of the Earth as moving through it.
Answer: Michelson postulated that the earth and the ether were moving at different velocities; one was moving relative to the other.  The first scenario had the earth move through and ether, while the second hand an ether wind blowing over earth.  Nevertheless, he ultimately proved that there was no such ether.  Since light reached the same point at the same time even though one travelled vertically and the other horizontally.
Comment: Sorry, but "Michelson postulated that the earth and the ether were moving at different velocities; one was moving relative to the other" is actually just the same thing said twice and doesn't really answer the question. The OP says he's aware that Michelson believed that there's relative motion and that the Michleson-Morely experiment disproved this with interferometers, but this answer doesn't mention the key point that this postulate was based on the intuitive model that the space between the sun and Earth was filled with ether because like sound, light needs some medium to travel through.
Answer: I believe there is a small misunderstanding as to what was moving.
At the time of Michelson and Morley's experiment, it was postulated that an aether must exist for light to be able to propagate.  It was also known that the earth revolves on its axis and moves around the sun.
Since the experiment's apparatus was "attached" to the earth, its motion trough the aether, would be equivalent to the eather moving through the apparatus.
In other words, by making the apparatus the "frame of reference," it gives the appearance that the aether is the one moving!


Why do dynamic arrays specifically double in size when running out of space?

Question: I'm new to amortized analysis. I've noticed that a common practice for dynamic arrays is to double their sizes when running out of space. Is there a specific reason why we choose to double the size? Why not triple or quadruple? Is there a specific explanation for the choice of doubling using amortized analysis? Or is the choice arbitrary?
Answer: Growing the array size by scaling by any constant factor will be sufficient to get the runtime to be O(n). To see this, note that if the final array size ends up at n and we scale by a factor of m on each step, then the total work done growing the array will be

1 + m + m2 + ... + m1+logm n.

To see why this is, note that (if the array starts at size one) then the array will grow at sizes 1, m, m2, ..., until it reaches size n. That last growth step happens when mk = n, which happens when k = logm n. Factoring in one more growth step to overshoot n accounts for the +1 here.
The above sum is a sum of a geometric series and sums to

(m2 + logmn - 1) / (m - 1)
= (m2n - 1)/ (m - 1)
≤ n · (m2 / (m - 1))

So basically any exponent greater than one works, but the leading coefficient depends on what choice of m we pick. For large m, this coefficient is approximately equal to m, and we end up wasting a lot of effort and space growing the array. If m gets closer to one, the denominator gets bigger and bigger and more of a concern.
Picking m = 2 gives a leading coefficient of 4, which is pretty low. Picking 1.5 gives a leading coefficient of 4.5. That's higher, but not by much. However, picking 1.5 has some other advantages:

The allocated array, if we keep growing the array, is never more than 50% bigger than what we had before. That reduces the overhead of the data structure compared with doubling.
If we need to grow the array, the sum of the sizes of the previous arrays exceeds the size of the new array (check this - powers of two don't do this). That makes it more likely that the memory allocator can recycle space from older discarded arrays to fit the new array.
Multiplying by 1.5 can be done by computing size + (size >> 1), which is extremely cheap on a processor compared with a multiply.

Hope this helps!
Answer: As you might have found in this post, the amortized complexity of the dynamic array is O(1). If you see the analysis, you will find that there is not any difference in the asymptotic time complexity if you change 2 to 3 or 4 or even to any other constant (greater than 1) number, even decimals. For example, in Microsoft Visual C++, using 1.5 as a growth factor [1] (see more cases in the provided link).
Hence, 2 is not a particular growth factor here and other factors are using as well. Moreover, as mentioned here:

Many textbooks, however, use a = 2 for simplicity and analysis purposes.
Comment: I've heard that some implementations use non-integer factors such as 1.5x.


Closing handles of a process as a regular user

Question: Here's the situation: As an adminstrator, I am able to stall the application by closing 2 handles held by the process. (Using ProcExplorer) . Is there any way/hack I can use to close file handles while as a regular user. handle.exe and ProcExplorer wont let me do so as a regular user. Is this because of Windows' security or because of ProcExplorer and Handle.exe's limitation ?
Comment: Is there any particular reason you need this functionality?
Comment: Yes to demonstrate a vulnerability.
Comment: Could you explain this more in deep please. What user the app runs exactly the name, and to what groups in belongs in windows and domain, if on domain, and is this the same user the main app runs?
Comment: Currently I'm thinking this is offtopic - it sounds like a general windows question. There is a hint of security question about it so I won't close unless it gets some votes/flags but can you clarify what the question is - Your final sentence looks on-topic, if limited but if you are asking 'show me a hack to breach windows security controls' then it will be off-topic.
Comment: I cant reveal the name of the software here for obvious reasons. But the situation leads to a DoS on the entire system when I close 2 RPC handles held by the process. I can do this using an Adminstrator Account having admin privileges. This counts as a vulnerability in itself. But, if a regular limited user, somehow could(using some code) also close the handle held by the said admin process, the impact of the vulnerability would be amplified.

@AndrewSmith : Yes this is the same process that runs on both admin as well as limited user accounts. OS is XP. Its a test system,hence no domains/group
Answer: Considering the only way you could get to the process is through debugging hooks (I think). The Local Security policy in windows 7 has the following for the debug permission:

Debug programs
This user right determines which users can attach a debugger to any
  process or to the kernel. Developers who are debugging their own
  applications do not need to be assigned this user right. Developers
  who are debugging new system components will need this user right to
  be able to do so. This user right provides complete access to
  sensitive and critical operating system components.
Caution
Assigning this user right can be a security risk. Only assign this
  user right to trusted users.
Default: Administrators

If this is the case only users with this permission could cause the issue you're referring to. Your bigger issue is users that are able to escalate permissions, but that's the battle we all fight.
Answer: This can be done ! Process explorer doesn't allow you to do it but you can write a simple python script to close the handles using the DUPLICATEHANDLE_CLOSE SOURCE can be used to close handles of the same user level processes.


How to add multiple computers in cisco packet tracer?

Question:
Hey, I'm the newbie of Cisco Packet Tracer. In the image as you can see there are lots of computers(0-99,1-200). I couldn't do that. Is it possible or it just some way of describing how much computers are there?
Comment: I've used packet tracer quite a bit and would say I've never seen this feature myself. I would assume the ellipses is really just text to describe a theoretical setup but there are really only the two PC's.
Answer: In packet tracer there's really only the computer you can actually see.
It's a principle schema to describe the topology and the core components of the network. The actual number of clients computers is not relevant to understand the network architecture.
As you correctly guessed it's only a way of displaying how many computers are connected in this VLAN but you can't connect 100 computers on a single switch in packet tracer. (So you may assume switch0 actually represents VLAN1 and is distributed on several physical switches)
The ellipse is a standard feature on the latest versions and the "..." is added using the "place note" feature (see screenshot below, keyboard shortcut "N"). It is recognizable due the very light grey background around the dots.
Answer: You can drag and drop as many computers you need/want from the "end devices" or something like that. Once you drag them in, you can connect them as you would like. You can get to CLI and that all of the other features. There are some things you can do, but I would encourage you to try it out and see what you can do! There are plenty of YouTube videos that can help.


Voltage in parallel and series connection

Question: In series connection, voltage is said to be different and current constant across the circuit. How does it come about ?  Is it due to the accumulation of electrons on one side due to resistors? Or, if it is so,  how is the situation reversed in the case of parallel connection?
Answer: In the series connection the current (charge passing a point per second) is the same every where because there are assumed to be no sources or sinks of charge and so the charge is conserved - the amount of charge entering is equal to the amount of charge leaving.  This is Kirchhoff's current law and there is certainly no accumulation of charge rather the charges are pushed through the resistors by the electric field produced by the battery.
You can liken the situation to some pipes connected in series with a pump forcing water through the pipes.
The rate at which water flows through the pipes (the current) is the same for each pipe although the pressure difference (the voltage) across each of the pipes is different.
Voltage is to do with the conversion of electrical energy into other forms of energy and the potential difference between two points is the work done in taking unit positive charge between those two points.  The work is done by the electric field produced by a power supply.
If you have a 10 ohm and a 5 ohm resistor in series and a current of $3$ amps going through them both then the voltage across the $10$ ohm resistor is $3 \times 10 = 30$ volts and the voltage across the $5$ ohm resistor is $5 \times 3 = 15$ volts.
What this means is that in taking one coulomb of charge through the $10$ ohm resistor $30$ joules of electrical energy is converted into heat whereas in taking the same amount of charge through the $5$ ohm resistor produces $15$ joules of heat.
In the case of resistors in parallel then the current which flows through each resistor is different but the work done in taking unit positive charge through each resistor, the voltage across the resistors, is the same.
This idea of the same work being done in taking unit charge between two points along different routes is very important.
This is equivalent to having a number of pipes all connected to the same outlet from a pump and the other end all connected together so the pressure exerted difference on the water (the voltage) across each of the pipes is the same although the rate of flow of water (current) through the pipes is different.
So with a $10$ ohm and a $5$ ohm resistor in parallel and a voltage of $10$ volts across them the current though the $10$ ohm resistor is $\frac {10}{10} = 1$ amp and the $5$ ohm resistor is $\frac {10}{5} = 2$ amp
More current flows through the path of least resistance ie through the $5$ ohm resistor but the conversion of electrical energy into heat per unit charge passing through eother resistor is the same.


Table view in mobile for comparision of data

Question: I have a table(in dashboard) where i compare data between two columns. I am trying to show the same data in mobile. I have 8 columns in total. I need to show at least 6 columns(Important) in mobile. How can i convert that to mobile.                            Use case : User has to compare Number of funded companies and Total funding's raised by individual companies for different business models.
Answer: I've had to do something similar.
I tried vertical columns at first with sticky table heading in order to keep context, but because the ten columns were long the user had to scroll both vertically and horizontally.
Afterwards, I tried horizontal columns. This way I could fit 10 columns in the same screen so there was no vertical scroll (except on 4" phones and down but even that was minimal compared to before).
I kept the sticky table heading on the left side (see the third mockup) to keep context (users still know in what column (row) they are looking).
I hope this helps.

download bmml source – Wireframes created with Balsamiq Mockups
Answer: For simplicity I will do it like this (the picture is taken from this link). The comparison will be divided one by one into 8 simple table (each per your comparison column). The title of each table is what attribute you want to compare per item. You use the first column of each table for the name/picture of the item you want to compare and the second row for comparison data.
This way no matter how long the content of the comparison data, it can always be overflowed to the y-direction without messing up the shape of the entire table(s). And also you only use vertical scroll to show all the contents. As we know horizontal scroll is uncommon in mobile application, especially for devices that utilize swipe left/right for page navigation.
If you expect to use many items for comparison, you also can make each table collapsible to simplify the view.