- Panoramas of Joplin Before and After the Tornado (Source)
- Inspectors say Greece missed all fiscal targets (Source)
- Samsung’s lawyers demand to see the iPhone 5 and iPad 3 (Source)
- 2011 Memorial Day in Tahoe: Shrinking beaches, snow-covered trails (Source)
- Germany: Ten die from E.coli-infected cucumbers (Source)
While I find many of his rhetorical tricks maddening — repeating something doesn’t make it truer; food inventories are not uniform; nothing interesting is monocausal; and reflexive contrarianism is exhausting — but this interview with Jim Rogers on BBC Hardtalk is worth a watch/listen.
I have meen messing about this week with <a href="http://www.bloomberg.com/apps/quote?ticker=GOOG:US" rel="nofollow"… [cont.]
I did a segment Thursday on Bloomberg TV about why the future of Microsoft, whatever that is, has to be without Steve Ballmer. And it also has to… [cont.]
Intriguing result with respect to the performance consequences of pre-event warmups. It turns out standard warmups — long-ish and moderate intensity — are bad for subsequent performance. Better is to do short, sharp effort, and that’s it.
Less is More: Standard Warm-up Causes Fatigue and Less Warm-up Permits Greater Cycling Power Output
Elias K. Tomaras1 and Brian R. MacIntosh1,*
The traditional warm-up (WU) athletes use to prepare for a sprint track cycling event involves a general WU followed by a series of brief sprints lasting at least 50 min in total. A WU of this duration and intensity could cause significant fatigue and impair subsequent performance. The purpose of this research was to compare a traditional WU to an experimental WU and examine the consequences of these on the 30 s Wingate test and electrically elicited twitch contractions. The traditional WU began with 20 min of cycling with a gradual intensity increase from 60% to 95% of maximal heart rate (HRmax). Following this, there were 4 sprints at 8 min intervals. The experimental WU was shorter with less high intensity exercise. Intensity increased from 60% to 70% HRmax over 15 min, and this was followed with just 1 sprint. The Wingate test was conducted with a 1 min lead-in at 80% of optimal cadence (OC), followed by a Wingate test at OC. Peak active twitch torque, after the traditional WU (86.5 ± 3.3 %) was significantly lower (p<0.05) than that after experimental WU (94.6 ± 2.4 %) when expressed as % of preWU amplitude. Wingate performance after experimental WU (PPO=1390 ± 80 W; Work=29.1 ± 1.2 kJ) was significantly better (p<0.01) than after traditional WU (PPO=1303 ± 89 W; Work=27.7 ± 1.2 kJ). The traditional track cyclists’ WU results in significant fatigue which corresponds with impaired peak power output. A shorter and lower intensity WU permits a better performance.
Long-time limit of world subway networks
Camille Roth, Soong Moon Kang, Michael Batty, Marc Barthelemy
We study the temporal evolution of the structure of the world’s largest subway networks. We show that, remarkably, all these networks converge to a shape which shares similar generic features despite their geographic and economic differences. This limiting shape is made of a core with branches radiating from it. For most of these networks, the average degree of the core has a value of order 2.5, slowly increases with time and displays small fluctuations. The current proportion of branches represents about 40% of the total number of stations and the average diameter of branches is about twice the average radial extension of the core. Spatial measures such as the number of stations at a given distance r to the barycenter display a first regime growing as r^2 followed by another regime with different exponents. These results — which are difficult to interpret in the framework of fractal geometry — confirm and find a natural explanation in the core and branches picture: the first regime corresponds to a uniform core, while the second regime is controlled by the interstation spacing on branches. The existence of a unique network shape in the temporal limit suggests the existence of dominant, universal mechanisms governing the evolution of these structures.
Another excerpt that caught my attention:
Indeed, for some of the networks — such as Moscow, Seoul, and Shanghai — we observe larger differences with respect to the average, limiting network. In the case of Moscow, its core appears over-developed compared to its branches. This network has resulted basically from a well-dened design and it is expected that it does not follow the same rules that govern networks evolving over a longer period which often appear to evolve in as lightly more self-organized manner. In the case of Seoul and Shanghai, it seems that their relatively young age could explain why they have not yet reached the longtime limit. We can note here that the least expensive way for these almost mature networks to reach the well-balanced long time limit is by constructing the minimum number of stations and lines and this then suggests that Seoul and Shanghai need to increase their core density hence the value of (t) (by adding inter-branches links for example) and Moscow needs to increase the number of its branches. It will be interesting to observe their future evolution.
Validation of Dunbar’s number in Twitter conversations
Bruno Goncalves, Nicola Perra, Alessandro Vespignani
Modern society’s increasing dependency on online tools for both work and recreation opens up unique opportunities for the study of social interactions. A large survey of online exchanges or conversations on Twitter, collected across six months involving 1.7 million individuals is presented here. We test the theoretical cognitive limit on the number of stable social relationships known as Dunbar’s number. We find that users can entertain a maximum of 100-200 stable relationships in support for Dunbar’s prediction. The “economy of attention” is limited in the online world by cognitive and biological constraints as predicted by Dunbar’s theory. Inspired by this empirical evidence we propose a simple dynamical mechanism, based on finite priority queuing and time resources, that reproduces the observed social behavior.