Joshua S. Dillon, Adrian Liu, and Max Tegmark:
A Fast Method for Power Spectrum and Foreground Analysis for 21 cm Cosmology
We develop and demonstrate an acceleration of the Liu & Tegmark quadratic estimator formalism for inverse variance foreground subtraction and power spectrum estimation in 21 cm tomography from O(N^3) to O(N log N), where N is the number of voxels of data. This technique makes feasible the megavoxel scale analysis necessary for current and upcoming radio interferometers by making only moderately restrictive assumptions about foreground models and survey geometry. We exploit iterative and Monte Carlo techniques and the symmetries of the foreground covariance matrices to quickly estimate the 21 cm brightness temperature power spectrum, P(k_parallel, k_perpendicular), the Fisher information matrix, the error bars, the window functions, and the bias. We also extend the Liu & Tegmark foreground model to include bright point sources with known positions in a way that scales as O[(N log N)(N point sources)] < O(N^5/3). As a first application of our method, we forecast error bars and window functions for the upcoming 128-tile deployment of the Murchinson Widefield Array, showing that 1000 hours of observation should prove sufficiently sensitive to detect the power spectrum signal from the Epoch of Reionization.
Congrats to Josh on submitting his first paper for publication!
Orbiting a star that is visible to the naked eye, astronomers have discovered a planet twice the size of our own made largely out of diamond.
The rocky planet, called ‘55 Cancri e’, orbits a sun-like star in the constellation of Cancer and is moving so fast that a year there lasts a mere 18 hours.
MIT:
Imagine that you have a big box of sand in which you bury a tiny model of a footstool. A few seconds later, you reach into the box and pull out a full-size footstool: The sand has assembled itself into a large-scale replica of the model.
That may sound like a scene from a Harry Potter novel, but it’s the vision animating a research project at the Distributed Robotics Laboratory (DRL) at MIT’s Computer Science and Artificial Intelligence Laboratory. At the IEEE International Conference on Robotics and Automation in May — the world’s premier robotics conference — DRL researchers will present a paper describing algorithms that could enable such “smart sand.” They also describe experiments in which they tested the algorithms on somewhat larger particles — cubes about 10 millimeters to an edge, with rudimentary microprocessors inside and very unusual magnets on four of their sides.
Unlike many other approaches to reconfigurable robots, smart sand uses a subtractive method, akin to stone carving, rather than an additive method, akin to snapping LEGO blocks together. A heap of smart sand would be analogous to the rough block of stone that a sculptor begins with. The individual grains would pass messages back and forth and selectively attach to each other to form a three-dimensional object; the grains not necessary to build that object would simply fall away. When the object had served its purpose, it would be returned to the heap. Its constituent grains would detach from each other, becoming free to participate in the formation of a new shape.
Study finds heart disease drug reduces racism
CBS:
Researchers from Oxford University released a new study in the international medical journal Psychopharmacology showing that taking propranolol reduces “implicit negative racial bias.”
[…]
Thirty-six white people were used in the study, with half getting propranolol and the other half getting a placebo. Researchers then used a feeling thermometer to rate how “warm” they felt toward different groups.
Researchers found that the heart disease drug “significantly lowered heart rate.” They also found that there was no significant difference between the propranolol and placebo groups toward religious or sexual prejudice.
“The main finding of our study is that propranolol significantly reduced implicit but not explicit racial bias,” researchers concluded.
The largest solar flare in five years is racing toward Earth, threatening to unleash a torrent of charged particles that could disrupt power grids, GPS and airplane flights.
The sun erupted Tuesday evening, and the effects should start smacking Earth around 7 a.m. EST Thursday (1200 GMT), according to forecasters at the federal government’s Space Weather Prediction Center. They say the flare is growing as it speeds outward from the sun.
“It’s hitting us right in the nose,” said Joe Kunches, a scientist for the National Oceanic and Atmospheric Administration.
![Science Daily:
Through a series of experiments, researchers from Polytechnic Institute of New York University (NYU-Poly) aimed to increase understanding of collective animal behavior, including learning how robots might someday steer fish away from environmental disasters. Nature is a growing source of inspiration for engineers, and the researchers were intrigued to find that their biomimetic robotic fish could not only infiltrate and be accepted by the swimmers, but actually assume a leadership role.
[…]
In an attempt to create a robotic leader, Marras and Porfiri placed their robot in a water tunnel with a golden shiner school. First, they allowed the robot to remain still, and unsurprisingly, the “dummy” fish attracted little attention. When the robot simulated the familiar tail movement of a leader fish, however, members of the school assumed the behavior patterns they exhibit in the wild, slowing their tails and following the robotic leader.](http://25.media.tumblr.com/tumblr_m08tqi0HP71qzpxq3o1_500.jpg)
Through a series of experiments, researchers from Polytechnic Institute of New York University (NYU-Poly) aimed to increase understanding of collective animal behavior, including learning how robots might someday steer fish away from environmental disasters. Nature is a growing source of inspiration for engineers, and the researchers were intrigued to find that their biomimetic robotic fish could not only infiltrate and be accepted by the swimmers, but actually assume a leadership role.
[…]
In an attempt to create a robotic leader, Marras and Porfiri placed their robot in a water tunnel with a golden shiner school. First, they allowed the robot to remain still, and unsurprisingly, the “dummy” fish attracted little attention. When the robot simulated the familiar tail movement of a leader fish, however, members of the school assumed the behavior patterns they exhibit in the wild, slowing their tails and following the robotic leader.
Japanese researchers build a gun capable of stopping speakers in mid-sentence
The idea is simple. Psychologists have known for some years that it is almost impossible to speak when your words are replayed to you with a delay of a fraction of a second.
Kurihara and Tsukada have simply built a handheld device consisting of a microphone and a speaker that does just that: it records a person’s voice and replays it to them with a delay of about 0.2 seconds. The microphone and speaker are directional so the device can be aimed at a speaker from a distance, like a gun.
In tests, Kurihara and Tsukada say their speech jamming gun works well: “The system can disturb remote people’s speech without any physical discomfort.”
“Education is what, when, and why to do things. Training is how to do it. In science, if you know what you are doing, you should not be doing it. In engineering, if you do not know what you are doing, you should not be doing it.”
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Richard Hamming, The Art of Doing Science and Engineering
New study suggests cognitive differences between political left and right
University of Nebraska-Lincoln:
From cable TV news pundits to red-meat speeches in Iowa and New Hampshire, our nation’s deep political stereotypes are on full display: Conservatives paint self-indulgent liberals as insufferably absent on urgent national issues, while liberals say fear-mongering conservatives are fixated on exaggerated dangers to the country.
A new study from the University of Nebraska-Lincoln suggests there are biological truths to such broad brushstrokes.
In a series of experiments, researchers closely monitored physiological reactions and eye movements of study participants when shown combinations of both pleasant and unpleasant images. Conservatives reacted more strongly to, fixated more quickly on, and looked longer at the unpleasant images; liberals had stronger reactions to and looked longer at the pleasant images compared with conservatives.
“It’s been said that conservatives and liberals don’t see things in the same way,” said Mike Dodd, UNL assistant professor of psychology and the study’s lead author. “These findings make that clear – quite literally.”
To gauge participants’ physiological responses, they were shown a series of images on a screen. Electrodes measured subtle skin conductance changes, which indicated an emotional response. The cognitive data, meanwhile, was gathered by outfitting participants with eyetracking equipment that captured even the most subtle of eye movements while combinations of unpleasant and pleasant photos appeared on the screen.
While liberals’ gazes tended to fall upon the pleasant images, such as a beach ball or a bunny rabbit, conservatives clearly focused on the negative images – of an open wound, a crashed car or a dirty toilet, for example.
Consistent with the idea that conservatives seem to respond more to negative stimuli while liberals respond more to positive stimuli, conservatives also exhibited a stronger physiological response to images of Democratic politicians – presumed to be a negative to them – than they did on pictures of well-known Republicans. Liberals, on the other hand, had a stronger physiological response to the Democrats – presumed to be a positive stimulus to them – than they did to images of the Republicans.
Breaking: Living with a political frame from the moment you are born changes your brain.
Hey guys, I’m really unimpressed by the space program. We should definitely cut its funding.
Micro needles could make getting a shot pain-free
Nobody likes getting shots. But what if you could make the needles so tiny that they broke the skin painlessly? Engineers from Tufts University have created such micro-needles—made from the major protein in silk, fibroin.
The researchers created molds for arrays of needles just 500 microns tall and 10 microns wide. That’s a tenth the width of the average human hair. They then poured a solution of fibroin mixed with a drug into the molds. The resulting micro-needles are dried and undergo further processing.
In tests, a patch containing numerous micro-needles successfully released the drug, which maintained its biological activity. The tiny needles are too short to reach the nerves under the skin, so they can deliver drugs without the pain of a traditional shot. Even better, they can gradually release medication over time. While skin patches and slow-release pills are currently used for this purpose, they only work with certain kinds of medication. The new micro-needle system could make the gradual delivery of many drugs smooth as silk.
NPR:
Scientists at the NASA’s Ames Research Center said today that for the first time, they have found a planet that orbits a star a lot like the sun and is smack in the middle of the “habitable zone.”
The exoplanet was found using the Kepler telescope, which was launched specifically to look for habitable planets. So far the mission has found more than 1,000 new candidates. But, today as part the Kepler’s team’s first science conference, NASA announced Kepler-22b, a special exoplanet that if found to be rocky could host life with a comfy temperature of 70 degrees Fahrenheit.
1 year ago
via 
It’s blue, comes from a creature more ancient than dinosaurs, and saves countless human lives. It’s the blood of horseshoe crabs, and for decades it’s proved vital to biomedical companies that must screen vaccines, IV fluids, and medical devices for bacteria that can be fatal in our bloodstream. Thanks to proteins in cells that act like a primitive immune system, the crabs’ blood coagulates instantly when it touches pathogens like E. coli and Salmonella.
So sensitive is the test derived from the proteins that it can detect amounts as slight as one part per trillion. That’s like one grain of sugar in an Olympic-size pool, says John Dubczak of test producer Charles River, Endosafe. Now Princeton University researchers are looking at another approach using synthetic molecules that replicate antimicrobial peptides found on the skin of African clawed frogs. That would take some of the heat off horseshoe crabs—if it can match the sensitivity of their millions-year-old strategy.
- About 500,000 horseshoe crabs are collected annually along the U.S. East Coast under interstate regulations.
- In a laboratory, blood is drawn from the crab’s primitive equivalent of a heart.
- The live crabs are returned to the sea. The estimated mortality rate is 15 percent.
- The blood’s blue color comes from copper in its oxygen-carrying protein, hemocyanin— akin to the iron-based hemoglobin in humans.
(via kateoplis)
