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Tourist Information Center:Turistični informacijski center Ptuj |
Slovenski trg 5 |
++386 2 779 60 11 |
232 m |
Height above sea level |
beside a lake; beside a river |
It is much easier to describe Ptuj's location between Slovenske gorice and Haloze and between Dravsko polje and Ptujsko polje than to write a short history of the city. Its history is rich and the city has numerous monuments to prove it. Its history reaches back to the Stone Age, but the city experienced its greatest f... |
Ptuj (360°) |
Ptuj arkade (360°) |
Ptuj monastery (360°) |
Points of distinction : Historical and cultural heritage. Wherever in the city the visitor stops, the heritage is the scenery around him: the almost entirely preserved medieval city core, the castle and the collections in it, the vaulted wine cellars beneath it, tens of thousands of archeological objects, among which t... |
Famous citizen : Ivan Potrč, author Janez Puh, inventor, factory owner Dr. Anton Slodnjak, literary linguist |
Association of Historic Cities of Slovenia |
Post Office : Ptuj |
Vodnikova ulica 2 |
++386 2 787 55 10 |
Bus station : Ptuj |
Osojnikova cesta 11 |
++386 2 771 14 91 |
Railway station : Ptuj |
Osojnikova cesta 2 |
++386 2 292 47 34 |
Medical center : Ptuj |
Potrčeva cesta 19 a |
++386 2 71 25 11 |
GPS Northing (N) : 46,4166 |
GPS Easting (E) : 15,8692 |
Administrator : TIC Ptuj | ++386 2 779 60 11 | | | last modified: 02/07/2014 |
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GPS N: 46,4166 |
E: 15,8692 |
Place: Ptuj |
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Anterior cruciate ligament- specialized post-operative return-to-sports (ACL-SPORTS) training: a randomized control trial |
Kathleen White*, Stephanie L Di Stasi, Angela H Smith and Lynn Snyder-Mackler |
BMC Musculoskeletal Disorders 2013, 14:108 doi:10.1186/1471-2474-14-108 |
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This morning Apple announced that sales of their $99 Apple TV would hit 1M units this week. While that's a nice round number to reach, it's not meaningful in the bigger picture and analysts who are quoted saying things like, "one million is a real benchmark" really don't understand the impact of devices on the over-the... |
Sales numbers for devices are pointless without talking about usage. I personally have two Apple TV's at home and rarely use them at all. In fact, I only use them when I want to test something or need to review certain functionality of the device. So how often are people using the Apple TV device and how much content a... |
Microsoft says that 42% of Xbox LIVE Gold members in the U.S. watch more than 30 hours of digitally distributed television and movies a month. Roku, who is due to reach 1M units sold by the end of this month said in September that the average Roku customer uses their device 43 hours a month. Those are the kinds of numb... |
And even the devices that do have a big footprint in the market like the Xbox 360 and PS3, both Microsoft and Sony won't tell us how many movies or TV shows they have sold or rented via their online services. Why? Because the numbers are still so small. I love devices, but we have to set the right expectations on the i... |
The Xbox 360 is the number one selling device in the home, connected to the TV and broadband and has sold 21.9M consoles in North America. That one device by itself has not made any content owner rich and has not changed the over-the-top video landscape in any drastic way. So why is Apple selling 1M devices considered ... |
And considering Apple is renting content for $0.99 on the Apple TV, there's just not a lot of revenue to be had. Lets assume that the average Apple TV user buys one video per week, for the entire course of the year. That's a content market size of only $52M a year today. And even if we assume Apple reaches the 5M sales... |
No matter how you run the numbers, they simply aren't big and it's one of the reasons why the studios are still fighting digital. They don't see the potential revenue yet and they won't for some time to come. Until we have mass-market penetration and usage of the devices, the studios won't have an incentive to give con... |
We see a lot of posts talking about devices, but how often do you see people talk about the sales numbers and usage of the devices? Most who are giving out quotes about these devices don't even know how many have been sold and haven't used the majority of the platforms they are talking about. Of course everyone always ... |
• Xbox 360: number sold as of Nov. 2010: 21.9M in NA, 45M worldwide (source: NPD) |
• PS3: number sold as of Sept. 2010: 16.6M in NA, 41.6M worldwide (source: Sony) |
• Roku: expect to reach 1M sold by end of 2010 (source: Roku) |
• Netgear Roku: number sold to date, too early to know |
• Apple TV: number sold as of December 2010: 1M (source: Apple) |
• Sony Netbox: number sold to date, too early to know |
• Boxee: number sold to date, too early to know |
• Logitech Revue Box, Sony Internet TV: number sold to date, too early to know |
• WD TV Live/Live Hub: number sold to date, no data released. I estimate less than 2M combined |
• TiVo: number sold to date: I estimate 750K TiVo HD units (source: estimate based on TiVo’s subscriber #s of 1.4M) |
• Broadband enabled TVs: iSuppli predicts almost 23M by 2013, TDG predicts 43M by 2014, DisplaySearch predicts 31M by 2013, Samsung predicts 20M by 2012 |
• Broadband enabled Blu-ray players: as of October 2010, the total installed base of Blu-ray Disc playback devices in the U.S. was 21.1M. What percentage of those are "broadband enabled" is not known. |
I constantly see people writing about devices, like this article yesterday, saying Amazon's Video On Demand service is available on the Xbox 360, even though it isn't. There is so much misinformation coming from the media and analysts on what these devices and platforms can or can't do, now just imagine what it's like ... |
In addition to setting the right expectations, analysts and bloggers also need to stop comparing hardware devices like Apple TV to platforms like Google TV. One has nothing do with the other and they don't compete at all, today. Apple sells a $99 piece of hardware, Google does not sell any hardware. Google is a platfor... |
The good news is that the quality of the video on these devices is getting better, the content being offered grows each year and content platforms like Netflix, VUDU, Zune Video, PlayStation Network, MLB, NHL, Hulu Plus and others are helping to create awareness and adoption. But with that awareness comes the problem w... |
Instead of so many analysts commenting on how many units of any device has been sold, I'd like to see them commenting on what the financial impact is on the industry from the usage of these devices. Who's making money from the adoption? How much money are they making? When will devices truly start impacting content lic... |
This post originally appeared on |
This article originally appeared at BusinessOfVideo. Copyright 2014. |
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In Weinberg: Gravitation and Cosmology chapter 2.10 (Relativistic Hydrodynamics) the speed of sound is derived as |
$v_s^2 = \left(\frac{\partial p}{\partial \rho}\right)$ |
and the equation of state is given as |
$p=(\gamma - 1) (\rho - nm)$ |
with $\gamma = 4/3$ for the case of a relativistic gas and $\gamma=5/3$ for the case of a nonrelativistic monoatomic gas ($nm$ is the rest mass density and $\rho$ the energy density). Then Weinberg computes the sound speed for the relativistic case as |
$v_s= \sqrt{\frac{1}{3}}$ |
in natural units and states that this is still safely less than unity (the speed of light). However what he doesn't show is the same calculation for the nonrelativistic case. This would yield |
$v_s^2 = \frac{\partial ((5/3 - 1) (\rho - nm))}{\partial \rho} = 2/3$ |
and so the speed of sound in the non-relativistic case would actually be $v_s =\sqrt{\frac{2}{3}}$. So the speed of sound for a non-relativistic gas is actually higher than the speed of sound for an relativistic gas!? However one usually computes the non-relativistic speed of sound with another equation of state |
which yields |
$v_s^2=\frac{p}{\rho} = K \gamma \rho^{\gamma-1} = \gamma \frac{p}{\rho}$ |
This is a completely different result compared to the one we get from the equation of state given by Weinberg. So is the equation of state given by Weinberg wrong? If so, what is the correct equation of state for a relativistic gas and what is the real maximum speed of sound for a relativistic gas? If not, what is wron... |
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2 Answers 2 |
Dear asmaier, sometimes it's useful to look into the real world to avoid some simple mistakes. The actual speed of sound in the air is 340 meters per second which is about one millionth of the speed of light. The squared speed of sound is one trillionth of the squared speed of light, so your claim that the non-relativi... |
The first formula by Weinberg that you quoted is universally valid but you apply it incorrectly. Well, Weinberg doesn't make these errors so that his first $\sqrt{1/3}$ result for the relativistic gas is correct, too. However, in particular, $(\rho-nm)$ is supposed to measure the energy above the latent energy of $E=mc... |
Clearly, $(\rho-nm)$ is negligibly small in the non-relativistic limit. So your $c\sqrt{2/3}$ for the nonrelativistic speed of sound is clearly invalid. In fact, $(\rho-nm)$ measures the kinetic energy of the molecules, $mv^2/2$; the factor of $m$ cancels. Because it will get differentiated and multiplied by $(\gamma-1... |
Recall that the (root mean square) speed of air molecules is 500 meters per second and the speed of sound is 340 meters per second. |
There is no contradiction between the relativistic formulae and the non-relativistic ones, which are the limits of the former, and the non-relativistic materials' speed of sound is vastly smaller than the speed of light. |
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The speed of sound in the non-relativistic regime is much smaller then the speed of sound and agrees with your final formula. To see that you should remember that the particle density $n(\rho)$ is not a constant, but it is a function of the energy density. In fact, for the non-relativistic fluid |
$$\rho(n)=nm c^2+\kappa n^{5/3}. $$ |
Now you can check that the energy dependence of the particle density will modify your relativistic calculation and the total result will agree with the correct final formula in your post. |
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A large yellowish-red FRUIT. |
Man, that sure is one strange mango. |
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