Group items tagged

for Tobi! nice analogy between the threat and the fast responding in human network

Yet another example of "because scientifically accurate title would sound sooo boring".

... proof that humanity is good?

"The dataset contains practically all actions of all players of the MMOG Pardus since the game went online in 2004 [18]. Pardus is an open-ended online game with a world- wide player base of currently more than 370,000 people. Play- ers live in a virtual, futuristic universe in which they interact with others in a multitude of ways to achieve their self-posed goals [22]. Most players engage in various economic activities typically with the (self-posed) goal to accumulate wealth and status. Social and economical decisions of players are often strongly influenced and driven by social factors such as friend- ship, cooperation, and conflict." quite impressive ...

Theoretized 80 years ago was Breit-Wheeler pair production in which two photons result in an electron-positron pair (via a virtual electron). It is a relatively simple Feynmann diagram, but the problem is/was how to produce in practice a high energy photon-photon collider... The collider experiment that the scientists have proposed involves two key steps. First, the scientists would use an extremely powerful high-intensity laser to speed up electrons to just below the speed of light. They would then fire these electrons into a slab of gold to create a beam of photons a billion times more energetic than visible light. The next stage of the experiment involves a tiny gold can called a hohlraum (German for 'empty room'). Scientists would fire a high-energy laser at the inner surface of this gold can, to create a thermal radiation field, generating light similar to the light emitted by stars. They would then direct the photon beam from the first stage of the experiment through the centre of the can, causing the photons from the two sources to collide and form electrons and positrons. It would then be possible to detect the formation of the electrons and positrons when they exited the can. Now this is a good experiment... :)

True, but isnt it E2=(pc)^2 + (m0c^2)^2 such that for photons E\propto{pc} and for mass E\propto{mc^2}. I agree it will take a lot of energy, but this assumes that that wont be the problem at least. The question therefore is whether the mass flow of the photon rocket (fuel consumed to create photons, eg fission/fusion) is higher/lower than the mass flow for e-p creation. You are probably right that the low e-p cross-section will favour direct use of photons to create low thrust for long periods of time, but with significant power available the ISP might be higher for e-p pair creation.

In essence the equation tells you that for photons with zero rest mass m0 all the energy will be converted to momentum of the particles. If you want to accelerate e-p then you first spend part of the energy on creating them (~511 keV each) and you can only use the remaining energy to accelerate them. In this case the equation gives you a lower particle momentum which leads to lower thrust (even when assuming 100% acceleration efficiency). ISP is a tricky concept in this case because there are different definitions which clash in the relativistic context (due to the concept of mass flow). R. Tinder gets to a I_SP = c (speed of light) for a photon rocket (using the relativistic mass of the photons) which is the maximum possible relativistic I_SP: http://goo.gl/Zz5gyC .

A new mechanism was discovered on how H2 and N2 participate in the radiation budget. This may help to resolve the "faint young sun paradox", a hypothesis according to which during the earlier age of the solar system when sun radiation had lower intensity than now, the earth was warmer. Extended, it could reassess the past habitability of Mars.

More in the ethic realm, I once was in a talk by Ivan Schuller (http://ischuller.ucsd.edu/) where he revisited the concept of Langmuir's Pathological Science (http://yclept.ucdavis.edu/course/280/Langmuir.pdf), defined as the act in which "people are tricked into false results ... by subjective effects, wishful thinking or threshold interactions" providing a list of aspects common to fraudulent science. Unfortunately there is no video of this very interesting talk, but the slides are available here: http://ethics.ucsd.edu/seminars/seminars/2006/summaries/Pathological_Science.pdf

"The experiments involve an oil droplet that bounces along the surface of a liquid. The droplet gently sloshes the liquid with every bounce. At the same time, ripples from past bounces affect its course. The droplet's interaction with its own ripples, which form what's known as a pilot wave, causes it to exhibit behaviors previously thought to be peculiar to elementary particles - including behaviors seen as evidence that these particles are spread through space like waves, without any specific location, until they are measured." Pilot-wave theory reresurrected. Maybe something for the next "fundamental" :P physics RF?

And for the next 'Experimental Physics Stagiaire' position why not try to do "Unpredictable Tunneling of a Classical Wave-Particle Association" http://stilton.tnw.utwente.nl/people/eddi/Papers/PhysRevLett_TUNNEL.pdf, there are some rumors online that the results of Yves Couder Experiments can be reproduced with simple DIY vibrating tables! It is very funny to see the videos of the MIT's replication of this experiment (with lightening legends for those who are uncomfortable with the concepts involved https://www.youtube.com/watch?v=YF5iHQMjcsM)

And the winner is... C++ :) Love the comment on Slashdot: "C++ Templates will turn the most pious programmer into a curse-slinging, chain-smoking alcoholic."

Nice one... However note the sample could be biased, because I'd expect some interaction between "using github" and "being a curse-slinging, chain-smoking alcoholic" ;-)

Fair enough :)

NASA Releases Tool Enabling Citizen Scientists to Examine Asteroid Vesta Vesta Trek is a free, web-based application that provides detailed visualizations of Vesta, one of the largest asteroids in our solar system. NASA's Dawn spacecraft studied Vesta from July 2011 to September 2012. Data gathered from multiple instruments aboard Dawn have been compiled into Vesta Trek's user-friendly set of tools, enabling citizen scientists and students to study the asteroid's features. The application includes: -- Interactive maps with the ability to overlay a growing range of data sets including topography, mineralogy, abundance of elements and geology, as well as analysis tools for measuring the diameters, heights and depths of surface features and more. -- 3-D printer-exportable topography so users can print physical models of Vesta's surface. -- Standard keyboard gaming controls to manoever a first-person visualization of "flying" across the surface of the asteroid. "There's nothing like seeing something with your own eyes, but these types of detailed data-visualizations are the next best thing," said Kristen Erickson, Director, Science Engagement and Partnerships at NASA Headquarters in Washington DC.

This collaborating swarm of drones acts as 3D pixels (voxels) to create giant, flying interactive displays.

I have never understood the flying part of these things. Isn't it really impracticle to have all those tiny quadrocopters zooming around. My money is on holography or still a google glass type of device, if only considering the energy requirements for doing anything kinetically.

IgNobel 2018 for literature. Btw, I never ever RTFM .. :)

Beautiful interactive tree of life

A bit slow, but I finally could figure out the common ancestor of the nine-banded armadillo and the common ostrich!

I agree soooo very much. An increasing number of journal and scientists are finally coming on board with this open science philosophy and I bet we will soon see a radical change of the whole peer review process and publication business

Let's keep a eye on this... Animals use odor cues to navigate through their environments, helping them locate targets and assess danger. Much of how animal brains organize, read out, and respond to odor stimuli across spatial and temporal scales is not well understood. To tackle these questions, Odor2Action uses a highly interdisciplinary team science approach. Our work uses fruit fly, honeybee, and mouse models to determine how neural representations of odor are generated, reformatted, and translated to generate useful behaviors that guide how animals interact with their environment.

reminds me of the methan smelling source finding study we did ...