Wikipedia:Reference desk/Archives/Science/2015 May 20

= May 20 =

USMLE Step 2 (Step 2 CS) must be taken before step 3?
there are: step 1, and step 2 CK + step 2 CS. My question is about the last one. It's not clear for me. 149.78.38.232 (talk) 01:32, 20 May 2015 (UTC)


 * For those not familiar with the acronym, our relevant articles are United States Medical Licensing Examination, USMLE Step 2 Clinical Knowledge, USMLE Step 2 Clinical Skills, & USMLE Step 3. -- ToE 02:33, 20 May 2015 (UTC)
 * USMLE Step 3 says: To be eligible to take the USMLE Step 3 exam, the physician must hold an M.D. or D.O. degree, and successfully pass the USMLE Step 1 and Step 2 Clinical Knowledge exams. International medical graduates must obtain certification by the Educational Commission for Foreign Medical Graduates (ECFMG) or successfully complete a “Fifth Pathway” program. The Step 2 CS may also be required. Hopefully someone else here will be able to describe under what conditions Step 2 CS is required. -- ToE 02:38, 20 May 2015 (UTC)
 * See USMLE's 2012 Bulletin, pg 4-5:
 * In order to be eligible to register for USMLE Step 3, graduates of LCME-accredited medical school programs or AOA-accredited medical schools are required to have passed Step 1 and Step 2. Such individuals must have passed Step 2 CS as part of the examination requirements for Step 3 if they: (a) have graduated from medical school in 2005 or later, or (b) graduated from medical school prior to 2005 but did not pass the CK component of Step 2 taken on or before June 30, 2005.
 * Note: After June 30, 2012, all graduates of LCME- and AOA-accredited medical schools will be required to take and pass Step 2 CS in order to be eligible for Step 3.
 * You shouldn't trust my interpretation, but this sounds like a grandfather clause which has lapsed, and that everyone has been required to take Step 2 CS prior to Step 3 for a few years now. I believe that the current Bulletin, under Eligibility Step 3:
 * To be eligible for Step 3, prior to submitting your application, you must:
 * pass Step 1, Step 2 CK, and Step 2 CS,
 * is sufficient to update our article to indicate that Step 2 CS is required.
 * is sufficient to update our article to indicate that Step 2 CS is required.
 * is sufficient to update our article to indicate that Step 2 CS is required.


 * The "Important" box two up from the "Step 3" section does seem to muddy the waters by saying that "Individuals who passed Step 2 prior to the implementation of Step 2 CS are not permitted to take Step 2 CK ... but are permitted to take Step 2 CS ... ." My understanding is that they are not only permitted to take Step 2 CS, but they are also required to take it in order to be eligible for Step 3.  Likewise, I understand second paragraph to be true -- if someone who prior to June 30, 2012 was not required to take Step 2 CS but did so anyhow and failed, then they have to retake it and pass before being eligible for Step 3 -- but that now holds for everyone, even those who had previously been grandfathered in and didn't take Step 2 CS.  It is strange that they would allude to the grandfather clause in the current Bulletin but not explicitly state that it has lapsed. -- ToE 14:12, 20 May 2015 (UTC)

X-7
In this video at about 14:00 and thereafter, what is the device making the infernal ringing/wailing sound? You know, that annoying "dililililing-ding-diling-diliiiiing" which starts right at the moment of the drop, and which can be heard even over the roar of the missile's ramjet -- which device is making that sound? 73.202.76.73 (talk) 09:51, 20 May 2015 (UTC)


 * It sounds like an analogue data channel being relayed through audio. I'm guessing it's signals from the craft's sensors. I could be wrong. 217.158.236.14 (talk) 10:28, 20 May 2015 (UTC)


 * Some links: Telemetry, Frequency-shift keying, and Lockheed X-7. -- ToE 13:05, 20 May 2015 (UTC)


 * Thanks! So I suppose the X-7 sent its telemetry using a dial-up modem, huh?  ;-) 73.202.76.73 (talk) 05:57, 21 May 2015 (UTC)


 * ;-). Of course the audio you hear was mixed by the documentary producers who would have had access to recordings of several different channels. The telemetry would have been transmitted on a different frequency than those being used for voice communications, and while someone in the control center might have had audio for the telemetry channel turned up just enough so that they could hear that a good signal was coming through, there's no reason to think that those in the control room were hearing it as loud as it is played in the documentary.  What I find most interesting is the engine noise, which suggests that they kept an open mic on the drone and transmitted the ambient sounds, presumably for analysis by the engineers designing the ramjet.


 * If you are interested in listening to the audio of various data transmission, there are several sites available to you online, such as the Signal Identification Guide wiki. Most moder transmissions will be at a higher data rate then the 1950s telemetry. -- ToE 12:12, 21 May 2015 (UTC)

Mobile tech
Why if contact less payment not taking off in many parts of the world as much as companies thought it would? And also same with e-boarding passes and tickets etc. — Preceding unsigned comment added by 176.27.10.0 (talk) 11:24, 20 May 2015 (UTC)


 * I use it all the time. I do find it limiting. Not all shops have the facility, and the limit for spending on the cards is still quite low. This stops me from using it quite a bit. 217.158.236.14 (talk) 12:22, 20 May 2015 (UTC)
 * But you don't see many people using it that often even if they have nfc phones. People seem to prefer cards. — Preceding unsigned comment added by 82.132.235.190 (talk) 16:10, 20 May 2015 (UTC)
 * People seem to prefer security. If a card appears to be more secure than NFC, then, I won't risk my pennies using NFC. Cards are convenient enough (for me). And the limitation on the amount that you can spend with NFC indicates that the providers believe it's not safe (yet). --Llaanngg (talk) 17:27, 20 May 2015 (UTC)
 * You're assuming it can be used with phones. In many places where contactless cards are common, support for contactless payment via NFC phones is limited, often dependent on the bank, phone and card and not necessarily easy to set-up even if it is supported. Actually probably the easiest way to enable contactless payment via your phone is to put on one of the stickers some banks provide which would interfere with the phones NFC. Nil Einne (talk) 21:38, 20 May 2015 (UTC)
 * Do you not just enter your PIN if it's above the spending limit? In NZ, if it's above the limit or you otherwise raise an alert, you can still use the contactless system but the terminal will ask for your PIN. It reduces the convience somewhat but it means you don't have to worry about the limit, and if for example you don't bother to take your card out of your wallet you can still do that. Nil Einne (talk) 21:38, 20 May 2015 (UTC)
 * See Legacy system and Vendor lock-in and Barriers to entry. The same problems exist for technologies such as fuel cell powered road vehicles and the like.  The catch-22 here is that vendors won't make the infrastructure change unless sufficient customer base has the new technology, however, customers won't buy the technology if they can't use it anywhere.  Anti-market forces, such as government mandates, are generally what is necessary to get things over the hump.  In many places, for example, Digital terrestrial television faced similar problems of adoption, so various governments basically mandated switch-over dates when the old technology would be forced to be abandoned.  See Digital television transition for how this worked.  It will probably take some sort of similar process to force out old magnetic stripe credit cards to replace it with contactless payment systems, smartchips, or something similar. -- Jayron 32 18:25, 20 May 2015 (UTC)
 * In the US, which is one of the few developed (or even I think better off developing) countries who still widely use magnetic stripe credit cards, the change to smartchip cards is basically being forced via increase fees and in particular the liability shift to any vendor who still only supports magnetic stripe cards (well actually non EMV terminals, but same diff) . Actually this is what happened in a lot of the rest of the world too, it's just happening a lot later in the US. That said, the US seems to be determined to stick with signatures whereas a lot of the world has moved to PIN . Contactless is a bit of a different issue. While there is some push for vendors to embrace contactless support, the biggest push seems to come from the claim that results in a noticable increase in spending. (This can be a big incentive. I've always wonder why payment at pump seemed to be so rare in NZ despite it being something I recall in Malaysia from about 20 years ago, and NZ widespread embrace of card payment. I read recently it's because the companies don't want them as forcing people to go in to the service station store results in a significant increase in purchases.) Nil Einne (talk) 21:51, 20 May 2015 (UTC)
 * FCVs are an appalling example, as there are fundamental physical reasons why hydrogen storage of energy is not ready for prime time.Greglocock (talk) 23:34, 20 May 2015 (UTC)

Professional - Master mariner
How long does it take, and how much does it cost, to obtain a Master mariner qualification, or some step leading to it? Can it be obtained cheaper or faster abroad, maybe in countries like Panama or Greece?--Llaanngg (talk) 17:09, 20 May 2015 (UTC)
 * In which country are you seeking a rating? Nimur (talk) 18:39, 20 May 2015 (UTC)


 * US, Canada, Western Europe to begin with, but unrestricted some day. --Llaanngg (talk) 16:48, 22 May 2015 (UTC)
 * Then, you should start by reading about license and certification procedures at the Coast Guard's information page:Merchant Mariner credentials procedure. If you are totally lost, read the Credentials FAQ, and their very nice Merchant Mariner Credential brochure; then find a regional examination center, and talk to an expert in the type of operation you are interested in conducting or on the type of vessel where you are seeking employment.  Do not try to take shortcuts: it will be much more difficult to obtain and then to transfer a foreign credential (unless you are already a credentialed foreign mariner): it is much more straightforward if you simply obtain the appropriate credentials in the United States.  One does not begin with a Master Mariner credential, either: you will need to work your way up to that level; you must have a certain experience (e.g. many years of service, at a lower pay grade, while exercising the privileges of a lower tier certification) to obtain the Master Mariner credential.  Nimur (talk) 17:50, 22 May 2015 (UTC)
 * Would you want to ride a ship under the control of someone who took a "faster and cheaper" route to get his certification? ←Baseball Bugs What's up, Doc? carrots→ 21:30, 20 May 2015 (UTC)


 * Linnaeus University do a Master Mariner course lasting 3 or 4 years, depending on what previous seagoing experience you have. see here. The course is in Swedish, so you will need to be proficient in that first. DuncanHill (talk) 22:28, 20 May 2015 (UTC)

What are these masts for?
I keep seeing these masts all over the place where I live in the north of England. What are they for? Are they for for mobile telephone antennae or something similar or do I need to start wearing a tinfoil hat?


 * It looks like a standard mobile phone mast possibly for the o2 network. MilborneOne (talk) 22:17, 20 May 2015 (UTC)
 * There is a searchable map of UK mobile phone masts on the Ofcom website if you want to be *really* sure, but that looks like a mobile mast.  FlowerpotmaN &middot;( t ) 22:39, 20 May 2015 (UTC)
 * Aha! spot on - according to the map it's an O2 mast. Thanks for that, I can keep the aluminium foil for the Sunday roast. Richerman    (talk) 23:17, 20 May 2015 (UTC)