The human body is a cross between a factory and a construction zone—at least on the cellular level. Certain proteins act as project managers, which direct a wide variety of processes and determine the fate of the cell as a whole.
In addition to its location in the cell nucleus, WDR5-EGFP was also found in central dark zone of the midbody. Credit: UCSB
One group of proteins called the WD-repeat (WDR) family helps a cell choose which of the thousands of possible gene products it should manufacture. These WDR proteins fold into a three-dimensional structure resembling a doughnut—an unusual shape that allows WDR proteins to act as stable platforms on which large protein complexes can assemble or disassemble.
A new study conducted by scientists at UC Santa Barbara reveals a novel function for WDR5, a protein known for its critical role in gene expression whereby information encoded in genes is converted into products like RNA (ribonucleic acid) and protein. In cells, WDR5 is a subunit of a five-protein complex. Mutations in members of this complex can result in childhood leukemia and other disorders affecting numerous organ systems in the body. The UCSB team worked with WDR5 in cultured human cell lines. The results of the study appear in the Journal of Biological Chemistry.
“We found that when two cells divide, WDR5 is localized to a very interesting cellular structure called the midbody,” said lead author Jeff Bailey, a graduate student in UCSB’s Department of Molecular, Cellular and Developmental Biology (MCDB). “In the past, although associated with cell division, the midbody was considered ‘junk,’ but that has changed in the last decade. Now the midbody is believed to be important during stem cell differentiation.”
Cytokinesis was substantially delayed and more cells failed to divide properly when WRD5 in cells was artificially reduced. Credit: UCSB
When a stem cell divides to produce a differentiated type of cell like a skin cell or a neuron, stem cells retain the midbody while differentiated cells do not. “This suggests that the midbody has important functions,” Bailey explained. “Also, when the midbody isn’t cut correctly, the cells can re-fuse, creating one cell with two nuclei. This is thought to be part of what happens when a tumor forms.”
Conducted in the laboratory of MCDB associate professor Zach Ma, this new work involved the fusion of WDR5 to a green fluorescent protein molecule called EGFP. Although dense material within the midbody thwarts conventional methods of protein detection, the fluorescence of EGFP tethered to WDR5 revealed its location during cell division, or cytokinesis.
The researchers were surprised to find WDR5 in a part of the midbody called the dark zone. “It was very unexpected,” Bailey said. “The presence of WDR5 outside the cell nucleus gave us a clue about its function, which we tested,” Ma added.
The scientists found that not only did the protein localize in the midbody, it also contributed to abscission, the separation of two daughter cells at the completion of cytokinesis. In addition, WDR5 promotes the disassembly of midbody microtubules, the major structural components of the midbody that must be cleared before abscission can occur.
When the investigators artificially reduced the amount of WDR5 in cells, cytokinesis was substantially delayed and more cells failed to divide properly. “When histology is performed on a tumor, pathologists look for cells that have two nuclei,” Bailey explained. “This can indicate that cells within the tumor are failing to properly finish cytokinesis.”
Because a single protein can perform several distinct functions according to its location within a cell, it can be challenging to study one function without disrupting the others. Guided by previous structural studies, however, the UCSB team identified surfaces of the WDR5 “doughnut” that may be specific to its role in cell division.
“We have shed some light on the role of WDR5 in cytokinesis,” Ma said, “which may in turn help us better understand the diverse array of physiological as well as pathological events related to malfunction of these proteins in the process of cell division.”
System for defending against memory-access attacks implemented in chips.
In the last 10 years, computer security researchers have shown that malicious hackers don’t need to see your data in order to steal your data. From the pattern in which your computer accesses its memory banks, adversaries can infer a shocking amount about what’s stored there.
A new memory-access protocol assigns every memory address to a single path (green) through a data structure known as a tree. But a given node of the tree will often lie along multiple paths (blue). Illustration: Christine Daniloff/MIT
The risk of such attacks is particularly acute in the cloud, where you have no control over whose applications are sharing server space with yours. An antagonist could load up multiple cloud servers with small programs that do nothing but spy on other people’s data.
Two years ago, researchers in the group of MIT’s Srini Devadas, the Edwin Sibley Webster Professor in MIT’s Department of Electrical Engineering and Computer Science, proposed a method for thwarting these types of attacks by disguising memory-access patterns. Now, they’ve begun to implement it in hardware.
In March, at the Architectural Support for Programming Languages and Operating Systems conference, they presented the layout of a custom-built chip that would use their scheme, which is now moving into fabrication. And at the IEEE International Symposium on Field-Programmable Custom Computing Machines in May, they will describe some additional improvements to the scheme, which they’ve tested on reconfigurable chips.
The principle behind the scheme is that, whenever a chip needs to fetch data from a particular memory address, it should query a bunch of other addresses, too, so that an adversary can’t determine which one it’s really interested in. Naturally, this requires shipping much more data between the chip and memory than would otherwise be necessary.
To minimize the amount of extra data needed, the researchers store memory addresses in a data structure known as a “tree.” A family tree is a familiar example of a tree, in which each “node” (a person’s name) is attached to only one node above it (the node representing the person’s parents) but may connect to several nodes below it (the person’s children).
Every address is randomly assigned to a path through the tree — a sequence of nodes stretching from the top of the tree to the bottom, with no backtracking. When the chip requires the data stored at a particular address, it also requests data from all the other nodes on the same path.
In earlier work, researchers in Devadas’ group were able to prove that pulling data from a single path was as confounding to an adversary as if the chip had pulled data from every single memory address in use — every node of the tree.
Breaking the logjam
After reading data from a path, however, the chip also has to write data to the whole path; otherwise, an adversary could determine which node was the one of interest. But the chip rarely stores data in the same node that it read it from.
Nodes often lie on multiple paths: To take the most basic example, the single node at the top, or root, of the tree lies on every path. When the chip writes a block of data to memory, it pushes it as far down the tree as it can, which means finding the last vacancy before the block’s assigned path branches off from path that was just read.
“The root of the tree is a lot smaller than the bottom of tree,” says Albert Kwon, an MIT graduate student in electrical engineering and computer science and one of the papers’ co-authors. “So intuitively, you want to push down as far as you can toward the bottom, so that there’s no congestion at the top.”
In writing data, the chip still has to follow the sequence of nodes in the path; otherwise, again, an adversary might be able to infer something about the data being stored. In previous attempts at similar systems, that meant sorting the memory addresses according to their ultimate locations in the tree.
“Sort is not easy to do in hardware,” says Chris Fletcher, another graduate student in Devadas’ group and first author on the new paper. “So by the time you’ve sorted everything, you’ve taken a real performance hit.”
In the chip described in their latest paper, Fletcher, Devadas, Kwon, and their co-authors — Ling Ren, also an MIT graduate student in electrical engineering and computer science, and colleagues at the University of Connecticut, the University of California at Berkeley, and the Qatar Computing Research Institute — took a different approach. They gave their chip an extra memory circuit, with storage slots that can be mapped onto the sequence of nodes in any path through the tree. Once a data block’s final location is determined, it’s simply stored at the corresponding slot in the circuit. All of the blocks are then read out in order.
Stockpiled secrets
The new chip features another trick to improve efficiency: Rather than writing data out every time it reads data in, it writes only on every fifth read. On the other reads, it simply discards all of the decoy data. When it finally does write data back out, it will have, on average, five extra blocks of data to store on the last path it read. But there are generally enough vacancies in the tree to accommodate the extra blocks. And when there aren’t, the system’s ordinary protocols for pushing data as far down the tree as possible can handle the occasional logjam at the top.
Today’s chips have small, local memory banks called caches in which they store frequently used data; for applications that use caching efficiently, all that extra reading and writing generally increases computation time by only about 20 percent. For applications that don’t use caching efficiently, computation time can increase fivefold, or even more.
But according to the researchers, one of the advantages of their scheme is that the circuits that implement it can simply be added to existing chip designs, without much retooling. The extra layer of security can then be switched on and off as needed. Some cloud applications may use it all the time; others may opt against it entirely; still others may activate it only when handling sensitive information, such as credit card numbers.
“This is groundbreaking work,” says Elaine Shi, an assistant professor of computer science at the University of Maryland who has studied similar security schemes. “For many years, this kind of secure algorithm has been prohibitive. This is basically the first time they’ve shown that you can achieve this 2x overhead. Previously, the overhead would be ridiculous, maybe in the tens of thousands. They built this thing and show that for, a class of benchmarks, the average slowdown is only 2x.”
“If you think about Java versus C, the slowdown is probably more than 2x,” she says. “Two-x is nothing. Plus, you only have to incur it for part of the code that touches sensitive data, like credit card numbers or genomic data.”
To look at the workings of a clutch and gearbox, we will be predominantly looking at an example of a car engine and the gearing system involved there.
The Gearbox
The gears are selected by a system of rods and levers operated by the gear lever. Drive is transmitted through the input shaft to the layshaft and then to the mainshaft, except in direct drive – top gear – when the input shaft and the mainshaft are locked together.
Internal-combustion engines run at high speeds, so a reduction in gearing is necessary to transmit power to the drive wheels, which turn much more slowly.
The gearbox provides a selection of gears for different driving conditions: standing start, climbing a hill, or cruising on level surfaces. The lower the gear, the slower the road wheels turn in relation to the engine speed.
The constant-mesh gearbox
The gearbox is the second stage in the transmission system, after the clutch. It is usually bolted to the rear of the engine, with the clutch between them.
Modern cars with manual transmissions have four or five forward speeds and one reverse, as well as a neutral position.
The gear lever, operated by the driver, is connected to a series of selector rods in the top or side of the gearbox. The selector rods lie parallel with shafts carrying the gears.
The most popular design is the constant-mesh gearbox. It has three shafts: the input shaft, the layshaft and the mainshaft, which run in bearings in the gearbox casing.
There is also a shaft on which the reverse-gear idler pinion rotates.
The engine drives the input shaft, which drives the layshaft. The layshaft rotates the gears on the mainshaft, but these rotate freely until they are locked by means of the synchromesh device, which is splined to the shaft.
It is the synchromesh device which is actually operated by the driver, through a selector rod with a fork on it which moves the synchromesh to engage the gear.
The baulk ring, a delaying device in the synchromesh, is the final refinement in the modern gearbox. It prevents engagement of a gear until the shaft speeds are synchronised.
On some cars an additional gear, called overdrive, is fitted. It is higher than top gear and so gives economic driving at cruising speeds.
Synchronising the gears
The synchromesh device is a ring with teeth on the inside that is mounted on a toothed hub which is splined to the shaft.
When the driver selects a gear, matching cone-shaped friction surfaces on the hub and the gear transmit drive, from the turning gear through the hub to the shaft, synchronising the speeds of the two shafts.
With further movement of the gear lever, the ring moves along the hub for a short distance, until its teeth mesh with bevelled dog teeth on the side of the gear, so that splined hub and gear are locked together.
Modern designs also include a baulk ring, interposed between the friction surfaces. The baulk ring also has dog teeth; it is made of softer metal and is a looser fit on the shaft than the hub.
The baulk ring must be located precisely on the side of the hub, by means of lugs or ‘fingers’, before its teeth will line up with those on the ring.
In the time it takes to locate itself, the speeds of the shafts have been synchronised, so that the driver cannot make any teeth clash, and the synchromesh is said to be ‘unbeatable’.
Most modern cars have synchromesh on all forward gears, but on earlier cars it is not provided on first gear.
Videos/animations of a Gearbox
Gearbox operation with clutch
How Manual Transmissions Work! (Animation)
How a Clutch Works
Fly Wheels, Clutch Plates and Friction
In a car’s clutch, a flywheel connects to the engine, and a clutch plate connects to the transmission. You can see what this looks like in the figure below.
When your foot is off the pedal, the springs push the pressure plate against the clutch disc, which in turn presses against the flywheel. This locks the engine to the transmission input shaft, causing them to spin at the same speed.
The amount of force the clutch can hold depends on the friction between the clutch plate and the flywheel, and how much force the spring puts on the pressure plate. The friction force in the clutch works just like the blocks described in the friction section of How Brakes Work, except that the spring presses on the clutch plate instead of weight pressing the block into the ground.
When the clutch pedal is pressed, a cable or hydraulic piston pushes on the release fork, which presses the throw-out bearing against the middle of the diaphragm spring. As the middle of the diaphragm spring is pushed in, a series of pins near the outside of the spring causes the spring to pull the pressure plate away from the clutch disc (see below). This releases the clutch from the spinning engine.
Note the springs in the clutch plate. These springs help to isolate the transmission from the shock of the clutch engaging. This design usually works pretty well, but it does have a few drawbacks. We’ll look at common clutch problems and other uses for clutches in the following sections.
We know of about two dozen runaway stars, and have even found one runaway star cluster escaping its galaxy forever. Now, astronomers have spotted 11 runaway galaxies that have been flung out of their homes to wander the void of intergalactic space.
“These galaxies are facing a lonely future, exiled from the galaxy clusters they used to live in,” said astronomer Igor Chilingarian (Harvard-Smithsonian Center for Astrophysics/Moscow State University). Chilingarian is the lead author of the study, which is appearing in the journal Science.
An object is a runaway if it’s moving faster than escape velocity, which means it will depart its home never to return. In the case of a runaway star, that speed is more than a million miles per hour (500 km/s). A runaway galaxy has to race even faster, traveling at up to 6 million miles per hour (3,000 km/s).
Chilingarian and his co-author, Ivan Zolotukhin (L’Institut de Recherche en Astrophysique et Planetologie/Moscow State University), initially set out to identify new members of a class of galaxies called compact ellipticals. These tiny blobs of stars are bigger than star clusters but smaller than a typical galaxy, spanning only a few hundred light-years. In comparison, the Milky Way is 100,000 light-years across. Compact ellipticals also weigh 1000 times less than a galaxy like our Milky Way.
Prior to this study, only about 30 compact elliptical galaxies were known, all of them residing in galaxy clusters. To locate new examples Chilingarian and Zolotukhin sorted through public archives of data from the Sloan Digital Sky Survey and the GALEX satellite.
Their search identified almost 200 previously unknown compact ellipticals. Of those, 11 were completely isolated and found far from any large galaxy or galaxy cluster.
This schematic illustrates the creation of a runaway galaxy. In the first panel, an “intruder” spiral galaxy approaches a galaxy cluster center, where a compact elliptical galaxy (cE) already revolves around a massive central elliptical galaxy. In the second panel, a close encounter occurs and the compact elliptical receives a gravitational kick from the intruder. In the third panel, the compact elliptical escapes the galaxy cluster while the intruder is devoured by the giant elliptical galaxy in the cluster center. Credit: NASA, ESA, and the Hubble Heritage Team
“The first compact ellipticals were all found in clusters because that’s where people were looking. We broadened our search, and found the unexpected,” said Zolotukhin.
These isolated compact galaxies were unexpected because theorists thought they originated from larger galaxies that had been stripped of most of their stars through interactions with an even bigger galaxy. So, the compact galaxies should all be found near big galaxies.
Not only were the newfound compact ellipticals isolated, but also they were moving faster than their brethren in clusters.
“We asked ourselves, what else could explain them? The answer was a classic three-body interaction,” stated Chilingarian.
A hypervelocity star can be created if a binary star system wanders close to the black hole at the center of our galaxy. One star gets captured while the other is thrown away at tremendous speed.
Similarly, a compact elliptical could be paired with the big galaxy that stripped it of its stars. Then a third galaxy blunders into the dance and flings the compact elliptical away. As punishment, the intruder gets accreted by the remaining big galaxy.
This discovery represents a prominent success of the Virtual Observatory – a project to make data from large astronomical surveys easily available to researchers. So-called data mining can result in finds never anticipated when the original data was collected.
“We recognized we could use the power of the archives to potentially unearth something interesting, and we did,” added Chilingarian.
– Credit and Resource –
More information: Isolated compact elliptical galaxies: Stellar systems that ran away, Science 24 April 2015: Vol. 348 no. 6233 pp. 418-421. DOI: 10.1126/science.aaa3344
The largest magmatic events on Earth are caused by massive melting of ascending large volumes of hot material from the Earth’s interior.
Gigantic volumes of hot material rising from the deep earth’s mantle to the base of the lithosphere have shaped the face of our planet. Provided they have a sufficient volume, they can lead to break-up of continents or cause mass extinction events in certain periods of the Earth’s history. So far it was assumed that because of their high temperatures those bodies – called mantle plumes – ascend directly from the bottom of the earth’s mantle to the lithosphere. In the most recent volume of Nature Communications, a team of researchers from the Geodynamic Modeling Section of German Research Centre for Geosciences GFZ explains possible barriers for the ascent of these mantle plumes and under which conditions the hot material can still reach the surface. In addition, the researchers resolve major conflicts surrounding present model predictions.
The largest magmatic events on Earth are caused by massive melting of ascending large volumes of hot material from the Earth’s interior. The surface manifestations of these events in Earth’s history are still visible in form of the basaltic rocks of Large Igneous Provinces. The prevailing concept of mantle plumes so far was that because of their high temperatures, they have strongly positive buoyancy that causes them to ascend and uplift the overlying Earth’s surface by more than one kilometer. In addition, it was assumed that these mantle plumes are mushroom-shaped with a large bulbous head and a much thinner tail with a radius of only 100 km, acting as an ascent channel for new material. But here is the problem: In many cases, this concept does not agree with geological and geophysical observations, which report much wider zones of ascending material and much smaller surface uplift.
Clouds over Australia are shown. Credit: NASA
The solution is to incorporate observations from plate tectonics: In many places on the Earth’s surface, such as in the subduction zones around the Pacific, ocean floor sinks down into the Earth’s mantle. Apparently, this material descends up to a great depth in the Earth’s mantle over several millions of years. This former ocean floor has a different chemical composition than the surrounding Earth’s mantle, leading to a higher density. If this material is entrained by mantle plumes, which is indicated by geochemical analyses of the rocks of Large Igneous Provinces, the buoyancy of the plume will decrease. However, this opens up the question if this hot material is still buoyant enough to rise all the way from the bottom of the Earth’s mantle to the surface.
GFZ-researcher Juliane Dannberg: “Our computer simulations show that on the one hand, the temperature difference between the plume and the surrounding mantle has to be high enough to trigger the ascent of the plume. On the other hand, a minimum volume is required to cross a region in the upper mantle where the prevailing pressures and temperatures lead to minerals with a much higher density than the surrounding rocks.”
Under these conditions, mantles plumes with very low buoyancy can develop, preventing them from causing massive volcanism and environmental catastrophes, but instead making them pond inside of the Earth’s mantle. However, mantle plumes that are able to ascend through the whole mantle are much wider, remain in the Earth’s mantle for hundreds of millions of years and only uplift the surface by a few hundred meters, which agrees with observations.
– Credit and Resource –
More information: Dannberg, J. and Sobolev, S.V., “Low-buoyancy thermochemical plumes resolve controversy of classical mantle plume concept”, Nature Communications, 24.04.2015, DOI: 10.1038/ncomms7960
Neural probes that combine optics, electronics, and drugs could help unlock the secrets of the brain.
Various powerful new tools for exploring and manipulating the brain have been developed over the last few years. Some use electronics, while others use light or chemicals.
At one MIT lab, materials scientist Polina Anikeeva has hit on a way to manufacture what amounts to a brain-science Swiss Army knife. The neural probes she builds carry light while collecting and transmitting electricity, and they also have tiny channels through which to pump drugs.
That’s an advance over metal wires or silicon electrodes conventionally used to study neurons. Anikeeva makes the probes by assembling polymers and metals into large-scale blocks, or preforms, and then stretching them into flexible, ultrathin fibers.
1. Blocks of polymers are the starting point for making a multifunctional neural probe. In a machine shop, patterns of conductive metal rods, transparent plastics, or hollow spaces will be added, creating a “preform.” 2. The preform is loaded into this 12-foot-tall fiber-drawing tower.
3. A collection of preform leftovers after drawing. Indium-tin rods are visible in what’s left of the preform at center.
4. Fiber is pulled from the furnace after being heated to 350 °C. A micrometer (red light) monitors the fiber’s size. 5. Each preform is drawn into as much as one kilometer of fiber. It is now about 1/100th as thick as it was originally.
6. A fiber soaks in THF, a solvent, to remove a protective cladding.
7. A cross section of a 0.35-millimeter- wide fiber containing four electrodes, a fluid channel, and a ring-shaped waveguide. At right, light shines through the waveguide.
8. This mouse has a fiber implanted in its brain. Visible on its head are a circuit board, a port to introduce light, and two more to inject drugs.
9. Optically stimulating the mouse’s brain produces the electrical activity recorded here.
Multifunctional fibers offer new ways to study animal behavior, since they can record from neurons as well as stimulating them. New types of medical technology could also result. Imagine, as Anikeeva does, bionic wiring that bridges a spinal-cord injury, collecting electrical signals from the brain and transmitting them to the muscles of a paralyzed hand.
Anikeeva made her first multifunctional probe while studying at Stanford. It was crude: she simply wrapped metal wires around a glass filament. But this made it possible to combine standard electrode measurements with a new technology, optogenetics, in which light is fired at neurons to activate them or shut them down.
Now Anikeeva, a professor of materials science and engineering, makes probes using a fiber-drawing technology developed by another MIT researcher, Yoel Fink. It’s based on the way silica is heated and pulled to form telecommunications fiber. But it works at lower temperatures, at which many useful polymers become soft enough to stretch.
Polymer fibers have a couple of important advantages. One is that they are flexible and mimic the physical properties of tissue. That could allow them to work longer than the stiff metal electrodes neuroscientists have relied on, permitting long-term studies in animals. The second feature of the fibers is that they can combine many functions. Probes made so far have incorporated as many as 36 microwires, optical waveguides, and hollow channels for carrying medicine. There’s no reason not to incorporate sensors to measure temperature or pressure as well. Inside the body, the right materials and structures might even entice nerves to attach to the fibers, the way bone fuses to a hip implant.
The fiber-drawing process shrinks large patterns into microscopic ones, preserving the details. But there are challenges. The tiny wires and tubes have to be stripped, splayed, and soldered by hand to connect them to components such as a recording device a mouse wears on its head. That’s quite a nightmare, says Andres Canales, a graduate student, who hopes to resolve the problem.
Will polymer bio-wires be what ultimately cures paralysis—say, by ferrying nerve signals across an injured spinal cord? “I think it will be a version of this technology, a more sophisticated version,” says Anikeeva. “At least we are going to pursue this route.”
A trio of researchers with the University of California has found that marmosets learn to wait for others to stop making noise before they vocalize, at a very young age. In their paper published in Proceedings of the Royal Society B, Cecilia Chow, Jude Mitchell and Cory Miller describe a study they undertook with young marmoset twins and their parents and what they learned by doing so.
Common marmoset. (Callithrix jacchus) Credit: Carmem A. Busko/Wikipedia/CC BY 2.5
In the primate world, only humans are able to listen to a sound made by someone else and mimic it, a skill that has led to communication and the different languages spoken around the world. Scientists know that part of communicating involves one person listening to what another says, before responding. This requires an ability to understand what it means to take turns when vocalizing. In this new study, the researchers have found that a young marmoset (a small silvery coated South American monkey) was also able to learn to take turns as part of vocalizing.
In their study, the researchers studied the vocalizations of a pair of captive marmoset twins (and their parents) over the first year of their life and report that they observed two parallels to language development. The first was that taking turns when vocalizing was a learned behavior. The second was that the young marmosets were essentially taught to take turns vocalizing by their parents in ways that are similar to the methods human parents use to teach children to wait for another person to finish speaking before they try to speak themselves.
In watching the monkeys as they grew, the researchers noted that if a youngster made a vocalization while a parent was vocalizing, that vocalization was typically ignored by the adult, which resulted over time in the youngster learning to wait for the adult to finish before vocalizing. They noted that as time passed, the young monkeys became less likely to interrupt—though it was more pronounced with their mother than with their father.
The researchers suggest their findings indicate a learning mechanism that is similar across all primates which could lead to a better understanding of the development of language in humans.
More information: Vocal turn-taking in a non-human primate is learned during ontogeny, Published 22 April 2015. DOI: 10.1098/rspb.2015.0069
Abstract
Conversational turn-taking is an integral part of language development, as it reflects a confluence of social factors that mitigate communication. Humans coordinate the timing of speech based on the behaviour of another speaker, a behaviour that is learned during infancy. While adults in several primate species engage in vocal turn-taking, the degree to which similar learning processes underlie its development in these non-human species or are unique to language is not clear. We recorded the natural vocal interactions of common marmosets (Callithrix jacchus) occurring with both their sibling twins and parents over the first year of life and observed at least two parallels with language development. First, marmoset turn-taking is a learned vocal behaviour. Second, marmoset parents potentially played a direct role in guiding the development of turn-taking by providing feedback to their offspring when errors occurred during vocal interactions similarly to what has been observed in humans. Though species-differences are also evident, these findings suggest that similar learning mechanisms may be implemented in the ontogeny of vocal turn-taking across our Order, a finding that has important implications for our understanding of language evolution.
Google said Wednesday it was launching its own US mobile wireless service, with considerable potential savings for customers using their devices at home and for international travel.
The service called Project Fi is only available by invitation for now, and only for the Google Nexus 6 smartphone.
The service will use Wi-Fi hotspots along with the US mobile networks of Sprint and T-Mobile, and also may be used in 120 countries without roaming charges.
It will be offered at a monthly cost of $20 for basic service plus $10 per month for each gigabyte of data used. Customers will only pay for the data they use, unlike some carriers which offer packages.
“Project Fi enables us to work in close partnership with leading carriers, hardware makers, and all of you to push the boundaries of what’s possible,” a Google blog post said.
“By designing across hardware, software and connectivity, we can more fully explore new ways for people to connect and communicate.”
The service “automatically connects to more than a million free, open Wi-Fi hotspots we’ve verified as fast and reliable,” Google said.
“When you’re not on Wi-Fi, we move you between whichever of our partner networks is delivering the fastest speed, so you get 4G LTE in more places.”
Google said the connections will be encrypted and the phone number “lives in the cloud, so you can talk and text with your number on just about any phone, tablet or laptop.”
For global travel, Project Fi will enable low-cost calling in many countries, and data access at 3G speeds without additional charges.
Ever since computers have been small enough to be fixtures on desks and laps, their central processing has functioned something like an atomic Etch A Sketch, with electromagnetic fields pushing data bits into place to encode data. Unfortunately, the same drawbacks and perils of the mechanical sketch board have been just as pervasive in computing: making a change often requires starting from the beginning, and dropping the device could wipe out the memory altogether. As computers continue to shrink—moving from desks and laps to hands and wrists—memory has to become smaller, stable and more energy conscious. A group of researchers from Drexel University’s College of Engineering is trying to do just that with help from a new class of materials, whose magnetism can essentially be controlled by the flick of a switch.
In spintronics memory applications, the spin of electrons can be controlled to encode data via the “up” and “down” binary pair of their spin. Credit: Drexel University
The team, led by Mitra Taheri, PhD, Hoeganaes associate professor in the College of Engineering and head of the Dynamic Characterization Group in the Department of Materials Science and Engineering, is searching for a deeper understanding of materials that are used in spintronic data storage. Spintronics, short for “spin transport electronics,” is a field that seeks to harness the natural spin of electrons to control a material’s magnetic properties. For an application like computing memory, in which magnetism is a key element, understanding and manipulating the power of spintronics could unlock many new possibilities.
Current computer data storage takes one of two main forms: hard drives or random access memories (RAM). You can think of a hard drive kind of like a record or CD player, where data is stored on one piece of material—a hard disk—and accessed by a magnetic read head, which is the computer’s equivalent of the record player’s needle or the CD player’s laser. RAM stores data by encoding it in binary patterns of electrical charges called bits. An external electric field nudges electrons into or out of capacitors to create the charge pattern and encode the data.
To store data in either type of memory device we must apply an external magnetic or electric field—either to read or write the data bits. And generating these fields draws quite a bit of energy. In a desktop computer that might go unnoticed, but in a handheld device or a laptop, quality is based, in large part, on how long the battery lasts.
Spintronic memory is an attractive alternative to hard drives and RAM because the material could essentially rewrite itself to store data. Eliminating the need for a large external magnetic field or a read head would make the device less power-intensive and more rugged because it has fewer moving parts.
“It’s the difference between a pre-whiteout typewriter and the first word processor,” said Steven Spurgeon, PhD, an alumnus whose doctoral work contributed to the team’s recently published research in Nature Communications. “The old method required you to move a read head over a bit and apply a strong magnetic field, while the newer one lets you insert data anywhere on the fly. Spintronics could be an excellent, non-destructive alternative to current hard drive and RAM devices and one that saves a great deal of battery life.”
Colorized scanning transmission electron micrograph of the LSMO / PZT interface. Using aberration-corrected electron microscopy, the authors are able to resolve small changes in atomic structure and chemistry at nearly the picometer scale. This yields a valuable and unprecedented new insight into the properties of oxide interfaces. Credit: Drexel University
While spintronic materials have been used in sensors and as part of hard drive read heads since the early 2000s, they have only recently been explored for direct use in memories. Taheri’s group is closely examining the physical principles behind spintronics at the atomic scale to look for materials that could be used in memory devices.
“We’re trying to develop a framework to understand how the many parameters—structure, chemistry, magnetism and electronic properties—are related to each other,” said Taheri, who is the principle investigator on the research program, funded by the National Science Foundation and the Office of Naval Research. “We’re peering into these properties at the atomic scale and probing them locally, in contrast to many previous studies. This is an important step toward more predictive and far-reaching use of spintronics.”
Theoretically, spintronic storage could encode data by tuning electron spins with help from a special, polarized electrical current running through the material. The binary pattern is then created by the “up” or “down” spin of the electrons, rather than their presence “in” or “out” of a capacitor.
To better understand how this phenomenon occurs, the team took a closer look at structure, chemistry and magnetism in a layered thin film oxide material that has shown promise for use in spintronic data storage, synthesized by researchers at the University of Illinois—Urbana Champaign.
RAM storage devices use electromagnetic fields to encode data via binary encryption. Credit: Drexel University
The researchers used advanced scanning transmission electron microscopy, electron energy loss spectroscopy and other high-resolution techniques to observe the material’s behavior at the intersections of the layers, finding that parts of it are unevenly electrically polarized—or ferroelectric.
“Our methodology revealed that polarization varies throughout the material—it is not uniform,” said Spurgeon, who is now a postdoctoral research associate at Pacific Northwest National Laboratory. “This is quite significant for spintronic applications because it suggests how the magnetic properties of the material can be tuned locally. This discovery would not have been possible without our team’s local characterization strategy.”
They also used quantum mechanical calculations to model and simulate different charge states in order to explain the behavior of the structures that they observed using microscopy. These models helped the team uncover the key links between the structure and chemistry of the material and its magnetic properties.
“Electronic devices are continually shrinking.” Taheri said. “Understanding these materials at the atomic scale will allow us to control their properties, reduce power consumption and increase storage densities. Our overarching goal is to engineer materials from the atomic scale all the way up to the macroscale in a predictable way. This work is a step toward that end.”
– Credit and Resource –
More information: Polarization screening-induced magnetic phase gradients at complex oxide interfaces, Nature Communications 6, Article number: 6735 DOI: 10.1038/ncomms7735
NASA is celebrating the Hubble Space Telescope’s 25th anniversary with a variety of events highlighting its groundbreaking achievements and scientific contributions with activities running April 20-26.
NASA’s Hubble Space Telescope is turning 25 this year. The observatory has transformed our understanding of our solar system and beyond, and helped us find our place among the stars. Credits: NASA
Hubble, the world’s first space telescope, was launched on April 24, 1990 aboard the space shuttle Discovery. In its quarter-century in orbit, the observatory has transformed our understanding of our solar system and beyond, and helped us find our place among the stars.
Starting at midnight EDT on Monday, April 20, and running through Sunday, April 26, images taken by the Hubble Space Telescope will be broadcast several times each hour on the Toshiba Vision dual LED screens in Times Square, New York.
The IMAX movie Hubble 3D is playing at select theatres across the United States throughout April. Hubble images come to vast, three-dimensional life, taking audiences through the telescope’s 25-year existence and putting them in orbit with astronauts during the latest servicing mission. For more information and the trailer, visit:
NASA Television will air the following anniversary events:
> Thursday, April 23 (9 to 9:45 a.m.) – Newseum, 555 Pennsylvania Ave. NW, Washington — NASA will unveil the official Hubble 25th anniversary image at this public event, with remarks by NASA Administrator Charlie Bolden, Associate Administrator for the Science Mission Directorate John Grunsfeld, Hubble Senior Project Scientist Jennifer Wiseman, and Space Telescope Science Institute Interim Director Kathryn Flanagan.
> Friday, April 24 (8 to 9 p.m.) – Smithsonian’s National Air and Space Museum, 600 Independence Ave. SW, Washington — Astronauts, scientists, engineers, technicians, educators, and staff who have contributed to Hubble’s success will be honored at a closed ceremony, followed by talks from prominent officials whose significant contribution to space science have made Hubble possible. For media interviews, contact Dwayne Brown at 202-358-1726, or dwayne.c.brown@nasa.gov.
> Saturday, April 25 (10 a.m. to 3 p.m.) – National Air and Space Museum’s Steven F. Udvar-Hazy Center, 14390 Air and Space Museum Pkwy., Chantilly, Virginia — The museum is holding an open family day event featuring panels of astronauts, scientists and engineers. Speakers will recount the history of Hubble and discuss its successor, the James Webb Space Telescope. For media interviews, contact Dwayne Brown at 202-358-1726, or dwayne.c.brown@nasa.gov. For more information, visit: http://airandspace.si.edu/events/detail.cfm?id=15779
For NASA TV streaming video, schedules and downlink information, visit:
Magnet-based setup may help detect the elusive mass of neutrinos.
MIT physicists have developed a new tabletop particle detector that is able to identify single electrons in a radioactive gas.
As the gas decays and gives off electrons, the detector uses a magnet to trap them in a magnetic bottle. A radio antenna then picks up very weak signals emitted by the electrons, which can be used to map the electrons’ precise activity over several milliseconds.
A new tabletop particle detector (shown here) is able to identify single electrons in a radioactive gas. Courtesy of the researchers
The team worked with researchers at Pacific Northwest National Laboratory, the University of Washington, the University of California at Santa Barbara (UCSB), and elsewhere to record the activity of more than 100,000 individual electrons in krypton gas.
The majority of electrons observed behaved in a characteristic pattern: As the radioactive krypton gas decays, it emits electrons that vibrate at a baseline frequency before petering out; this frequency spikes again whenever an electron hits an atom of radioactive gas. As an electron ping-pongs against multiple atoms in the detector, its energy appears to jump in a step-like pattern.
“We can literally image the frequency of the electron, and we see this electron suddenly pop into our radio antenna,” says Joe Formaggio, an associate professor of physics at MIT. “Over time, the frequency changes, and actually chirps up. So these electrons are chirping in radio waves.”
Formaggio says the group’s results, published in Physical Review Letters, are a big step toward a more elusive goal: measuring the mass of a neutrino.
Shown here is “event zero,” the first detection of a trapped electron in the MIT physicists’ instrument. The color indicates the electron’s detected power as a function of frequency and time. The sudden “jumps” in frequency indicate an electron collision with the residual hydrogen gas in the cell. Courtesy of the researchers
A ghostly particle
Neutrinos are among the more mysterious elementary particles in the universe: Billions of them pass through every cell of our bodies each second, and yet these ghostly particles are incredibly difficult to detect, as they don’t appear to interact with ordinary matter. Scientists have set theoretical limits on neutrino mass, but researchers have yet to precisely detect it.
“We have [the mass] cornered, but haven’t measured it yet,” Formaggio says. “The name of the game is to measure the energy of an electron — that’s your signature that tells you about the neutrino.”
As Formaggio explains it, when a radioactive atom such as tritium decays, it turns into an isotope of helium and, in the process, also releases an electron and a neutrino. The energy of all particles released adds up to the original energy of the parent neutron. Measuring the energy of the electron, therefore, can illuminate the energy — and consequently, the mass — of the neutrino.
Scientists agree that tritium, a radioactive isotope of hydrogen, is key to obtaining a precise measurement: As a gas, tritium decays at such a rate that scientists can relatively easily observe its electron byproducts.
Researchers in Karlsruhe, Germany, hope to measure electrons in tritium using a massive spectrometer as part of an experiment named KATRIN (Karlsruhe Tritium Neutrino Experiment). Electrons, produced from the decay of tritium, pass through the spectrometer, which filters them according to their different energy levels. The experiment, which is just getting under way, may obtain measurements of single electrons, but at a cost.
“In KATRIN, the electrons are detected in a silicon detector, which means the electrons smash into the crystal, and a lot of random things happen, essentially destroying the electrons,” says Daniel Furse, a graduate student in physics, and a co-author on the paper. “We still want to measure the energy of electrons, but we do it in a nondestructive way.”
The group’s setup has an additional advantage: size. The detector essentially fits on a tabletop, and the space in which electrons are detected is smaller than a postage stamp. In contrast, KATRIN’s spectrometer, when delivered to Karlsruhe, barely fit through the city’s streets.
A three-dimensional interpretation of “event zero.” The frequency increases slowly as the electron loses energy, ending in the first of six or possibly seven visible frequency jumps before the electron is ejected from the trap. Courtesy of the researchers
Tuning in
Furse and Formaggio’s detector — an experiment called “Project 8” — is based on a decades-old phenomenon known as cyclotron radiation, in which charged particles such as electrons emit radio waves in a magnetic field. It turns out electrons emit this radiation at a frequency similar to that of military radio communications.
“It’s the same frequency that the military uses — 26 gigahertz,” Formaggio says. “And it turns out the baseline frequency changes very slightly if the electron has energy. So we said, ‘Why not look at the radiation [electrons] emit directly?’”
Formaggio and former postdoc Benjamin Monreal, now an assistant professor of physics at UCSB, reasoned that if they could tune into this baseline frequency, they could catch electrons as they shot out of a decaying radioactive gas, and measure their energy in a magnetic field.
“If you could measure the frequency of this radio signal, you could measure the energy potentially much more accurately than you can with any other method,” Furse says. “The problem is, you’re looking at this really weak signal over a very short amount of time, and it’s tough to see, which is why no one has ever done it before.”
It took five years of fits and starts before the group was finally able to build an accurate detector. Once the researchers turned the detector on, they were able to record individual electrons within the first 100 milliseconds of the experiment — although the analysis took a bit longer.
“Our software was so slow at processing things that we could tell funny things were happening because, all of a sudden, our file size became larger, as these things started appearing,” Formaggio recalls.
He says the precision of the measurements obtained so far in krypton gas has encouraged the team to move on to tritium — a goal Formaggio says may be attainable in the next year or two — and pave a path toward measuring the mass of the neutrino.
Steven Elliott, a technical staff member at Los Alamos National Laboratory, says the group’s new detector “represents a very significant result.” In order to use the detector to measure the mass of a neutrino, Elliott adds, the group will have to make multiple improvements, including developing a bigger cell to contain a larger amount of tritium.
“This was the first step, albeit a very important step, along the way to building a next-generation experiment,” says Elliott, who did not contribute to the research. “As a result, the neutrino community is very impressed with the concept and execution of this experiment.”
This research was funded in part by the Department of Energy and the National Science Foundation.
The destruction of a planet may sound like the stuff of science fiction, but a team of astronomers has found evidence that this may have happened in an ancient cluster of stars at the edge of the Milky Way galaxy.
Using several telescopes, including NASA’s Chandra X-ray Observatory, researchers have found evidence that a white dwarf star – the dense core of a star like the Sun that has run out of nuclear fuel – may have ripped apart a planet as it came too close.
How could a white dwarf star, which is only about the size of the Earth, be responsible for such an extreme act? The answer is gravity. When a star reaches its white dwarf stage, nearly all of the material from the star is packed inside a radius one hundredth that of the original star. This means that, for close encounters, the gravitational pull of the star and the associated tides, caused by the difference in gravity’s pull on the near and far side of the planet, are greatly enhanced. For example, the gravity at the surface of a white dwarf is over ten thousand times higher than the gravity at the surface of the Sun.
Researchers used the European Space Agency’s INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) to discover a new X-ray source near the center of the globular cluster NGC 6388. Optical observations had hinted that an intermediate-mass black hole with mass equal to several hundred Suns or more resides at the center of NGC 6388. The X-ray detection by INTEGRAL then raised the intriguing possibility that the X-rays were produced by hot gas swirling towards an intermediate-mass black hole.
In a follow-up X-ray observation, Chandra’s excellent X-ray vision enabled the astronomers to determine that the X-rays from NGC 6388 were not coming from the putative black hole at the center of the cluster, but instead from a location slightly off to one side. A new composite image shows NGC 6388 with X-rays detected by Chandra in pink and visible light from the Hubble Space Telescope in red, green, and blue, with many of the stars appearing to be orange or white. Overlapping X-ray sources and stars near the center of the cluster also causes the image to appear white.
With the central black hole ruled out as the potential X-ray source, the hunt continued for clues about the actual source in NGC 6388. The source was monitored with the X-ray telescope on board NASA’s Swift Gamma Ray Burst mission for about 200 days after the discovery by INTEGRAL.
The source became dimmer during the period of Swift observations. The rate at which the X-ray brightness dropped agrees with theoretical models of a disruption of a planet by the gravitational tidal forces of a white dwarf. In these models, a planet is first pulled away from its parent star by the gravity of the dense concentration of stars in a globular cluster. When such a planet passes too close to a white dwarf, it can be torn apart by the intense tidal forces of the white dwarf. The planetary debris is then heated and glows in X-rays as it falls onto the white dwarf. The observed amount of X-rays emitted at different energies agrees with expectations for a tidal disruption event.
The researchers estimate that the destroyed planet would have contained about a third of the mass of Earth, while the white dwarf has about 1.4 times the Sun’s mass.
While the case for the tidal disruption of a planet is not iron-clad, the argument for it was strengthened when astronomers used data from the multiple telescopes to help eliminate other possible explanations for the detected X-rays. For example, the source does not show some of the distinctive features of a binary containing a neutron star, such as pulsations or rapid X-ray bursts. Also, the source is much too faint in radio waves to be part of a binary system with a stellar-mass black hole.
– Credit and Resource –
More information: “The puzzling source IGR J17361-4441 in NGC 6388: a possible planetary tidal disruption event.” Monthly Notices of the Royal Astronomical Society, 444(1), 93–101. DOI: 10.1093/mnras/stu1436
Research on a modified protein around which DNA is wrapped sheds light on how gene regulation is linked to aging and longevity in nematodes, fruit flies and possibly humans.
The research has implications for how gene expression is regulated, and could offer a new drug target for age-related diseases.
The Cornell study, published April 1 in the journal Genes and Development, focuses on a specific modification of the histone protein H3. Histone proteins, which are like spools in which DNA is the thread, are essential for packaging DNA in cells. Histones can be modified in many ways, which affects how the DNA is packaged, and how genes are turned on and off. The H3 modification, named H3K36me3, refers to a chemical mark placed at a specific position on the H3 protein.
Sylvia Lee, associate professor of molecular biology and genetics in the College of Arts and Sciences, is the paper’s senior author, and Mintie Pu, a postdoctoral researcher in Lee’s lab, is first author.
For their study, the researchers profiled a genomewide pattern of the H3 modification, and then profiled the expression of all genes in young and old C. elegans nematodes. They found that when genes wrapped around H3 proteins, if the modification existed at low levels, expression of those genes tended to fluctuate with age. At the same time, the expression of genes that wrapped around high levels of the same modification remained stable with age.
“If this histone protein mark is found at a high level, it can stabilize gene expression through the aging process,” said Lee.
The researchers questioned whether this pattern was unique to C. elegans or could be observed generally in other species. Working with collaborators at Brown University, the team examined data from fruit flies (Drosophila melanogaster) and found the same correlation.
“We have good reason to think what we are seeing is very likely to be conserved in humans,” Lee said.
The researchers then deleted an enzyme in C. elegans that normally facilitates the chemical mark on H3 proteins, so that the modification was no longer present. Without it, gene expression became more variable with age and those nematodes had shorter lifespans, Lee said.
“We speculate that this histone protein mark is important for preserving normal longevity,” she said.
The next step will be to test whether the findings in nematodes and fruit flies hold true for mammals and humans. Even though the H3 modification is found in many different cells, including human cells, not much is known about its functions. Future study could add to fundamental understanding of gene regulation, Lee said.
Clinically speaking, the H3K36me3 modification has links to developmental defects and cancer development. “A protein partner that recognizes this histone modification and mediates disease outcomes could be a target point” for future therapies, Lee said.
– Credit and Resource –
More information: “Trimethylation of Lys36 on H3 restricts gene expression change during aging and impacts life span.” Genes & Development, 29(7), 718–731. DOI: 10.1101/gad.254144.114
The honey badger (Mellivora capensis), also known as the Ratel, is a species of mustelid native to Africa, Southwest Asia, and the Indian Subcontinent. Despite its name, the honey badger does not closely resemble other badger species; instead, it bears more anatomical similarities to weasels. It is classed as Least Concern by the IUCN owing to its extensive range and general environmental adaptations. It is primarily a carnivorous species and has few natural predators because of its thick skin and ferocious defensive abilities.
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Carnivora Family: Mustelidae Subfamily: Mellivorinae Genus: Mellivora (Storr, 1780) Species: M. capensis
Taxonomy: As many as 10 subspecies suggested, currently being revised.
Size:
Total length:780 to 1020mmm Head: 25 to 155 mm Body: 500 to 640 mm Tail: 160 to 230mm Shoulder height: 230 to 300 mm Neck circumference: 225 to 355 mm Weight:Male: 9.0 to 14.0 kg, Female:5.5 to 10.0 kg
Diet: Generalist carnivore General distribution: The greater part of sub-Saharan Africa, through the Middle East to southern Russia, and eastwards as far as India and Nepal. Habitat: Wide tolerance, from semi-desert to rainforest. Altitude: Sea level to 4,050 meters. Longevity: Estimated 5 to 8 years in wild, 24 years in captivity. Social system: Solitary, polygynous, males may form small groups. Breeding season: None, breed throughout year. Gestation: 6 – 8 weeks typical (may exhibit delayed implantation in some areas). More data needed Litter size: 1 rarely 2 cubs Conservation status: Unprotected on International Red Data List, Near Threatened in South Africa. , Near Threatened in Morocco, Endangered in Saudi Arabia, protected in India. Threats: Directly persecuted by bee- keepers, poultry and sheep farmers. Indirect persecution through indiscriminate poisoning and trapping for jackal and caracal. Trade for traditional medicine. Bushmeat in Zambia. Predators: Lion,leopard and man.
Taxonomy
The honey badger is the only species of the genus Mellivora. Although in the 1860s it was assigned to the badger subfamily, the Melinae, it is now generally agreed that it bears very few similarities to the Melinae. It is much more closely related to the marten subfamily, Mustelinae, but furthermore is assigned its own subfamily, Mellivorinae. Differences between Mellivorinae and Melinae include differences in their dentition formulae. Though not in the same subfamily as the wolverines, which are a genus of large-sized and atypical Mustelinae, the honey badger can be regarded as another, analogous, form of outsized weasel or polecat.
The species first appeared during the middle Pliocene in Asia. Its closest relation was the extinct genus Eomellivora, which is known from the upper Miocene, and evolved into several different species throughout the whole Pliocene in both the Old and New World.
A Physical Description of the Honey Badger
The honey badger has a fairly long body, but is distinctly thick-set and broad across the back. Its skin is remarkably loose, and allows it to turn and twist freely within it. The skin around the neck is 6 millimetres (0.24 in) thick, an adaptation to fighting conspecifics. The head is small and flat, with a short muzzle. The eyes are small, and the ears are little more than ridges on the skin, another possible adaptation to avoiding damage while fighting.
The honey badger has short and sturdy legs, with five toes on each foot. The feet are armed with very strong claws, which are short on the hind legs and remarkably long on the forelimbs. It is a partially plantigrade animal whose soles are thickly padded and naked up to the wrists. The tail is short and is covered in long hairs, save for below the base.
Honey badgers are the largest terrestrial mustelids in Africa. Adults measure 23 to 28 cm (9.1 to 11.0 in) in shoulder height and 55–77 cm (22–30 in) in body length, with the tail adding another 12–30 cm (4.7–11.8 in). Females are smaller than males. Males weigh 9 to 16 kg (20 to 35 lb) while females weigh 5 to 10 kg (11 to 22 lb) on average. Skull length is 13.9–14.5 cm (5.5–5.7 in) in males and 13 cm (5.1 in) for females.
Skull, as illustrated by N. N. Kondakov.
There are two pairs of mammae. The honey badger possesses an anal pouch which, unusual among mustelids, is eversible, a trait shared with hyenas and mongooses. The smell of the pouch is reportedly “suffocating”, and may assist in calming bees when raiding beehives.
The skull bears little similarity to that of the European badger, and greatly resembles a larger version of a marbled polecat skull. The skull is very solidly built, with that of adults having no trace of an independent bone structure. The braincase is broader than that of dogs.
Honey Badger Teeth
The dental formula is: 3.1.3.13.1.3.1. The teeth often display signs of irregular development, with some teeth being exceptionally small, set at unusual angles or are absent altogether. Honey badgers of the subspecies signata have a second lower molar on the left side of their jaws, but not the right. Although it feeds predominantly on soft foods, the honey badger’s cheek teeth are often extensively worn. The canine teeth are exceptionally short for carnivores. The tongue has sharp, backward-pointing papillae which assist it in processing tough foods.
Honey Badger Habits and Behaviors
Although mostly solitary, honey badgers may hunt together in pairs during the May breeding season. Little is known of the honey badger’s breeding habits. Its gestation period is thought to last six months, usually resulting in two cubs, which are born blind. They vocalise through plaintive whines. Its lifespan in the wild is unknown, though captive individuals have been known to live for approximately 24 years.
Honey badgers live alone in self-dug holes. They are skilled diggers, able to dig tunnels into hard ground in 10 minutes. These burrows usually only have one passage and a nesting chamber and are usually only 1–3 m long. They do not place bedding into the nesting chamber. Although they usually dig their own burrows, they may take over disused aardvark and warthog holes or termite mounds.
Honey badgers are intelligent animals and are one of a few species known to be capable of using tools. In the 1997 documentary series Land of the Tiger, a honey badger in India was filmed making use of a tool; the animal rolled a log and stood on it to reach a kingfisher fledgling stuck up in the roots coming from the ceiling in an underground cave. A video made at the Moholoholo rehab centre in South Africa showed a pair of honey badgers using sticks, a rake, heaps of mud and stones to escape from their walled pit.
As with other mustelids of relatively large size, such as wolverines and badgers, honey badgers are notorious for their strength, ferocity and toughness. They have been known to savagely and fearlessly attack almost any kind of animal when escape is impossible, reportedly even repelling much larger predators such as lions. Bee stings, porcupine quills, and animal bites rarely penetrate their skin. If horses, cattle, or Cape buffalos intrude upon a ratel’s burrow, it will attack them. They are virtually tireless in combat and can wear out much larger animals in physical confrontations. The aversion of most predators toward hunting honey badgers has led to the theory that the countershaded coats of cheetah kittens evolved in imitation of the honey badger’s colouration to ward off predators.
The voice of the honey badger is a hoarse “khrya-ya-ya-ya” sound. When mating, males emit loud grunting sounds. Cubs vocalise through plaintive whines. When confronting dogs, honey badgers scream like bear cubs.
Honey Badger’s Diet
Next to the wolverine, the honey badger has the least specialised diet of the weasel family. In undeveloped areas, honey badgers may hunt at any time of the day, though they become nocturnal in places with high human populations. When hunting, they trot with their foretoes turned in. Honey badgers favor bee honey, and will often search for beehives to get it, which earns them their name. They are also carnivorous and will eat insects, frogs, tortoises, rodents, turtles, lizards, snakes, eggs, and birds. Honey badgers have even been known to chase away young lions and take their kills. They will eat fruit and vegetables such as berries, roots and bulbs. Despite popular belief, there is no evidence that honeyguides (a bird species that eats bee larvae) guide the honey badger.
They may hunt frogs and rodents such as gerbils and ground squirrels by digging them out of their burrows. Honey badgers are able to feed on tortoises without difficulty, due to their powerful jaws. They kill and eat snakes, even highly venomous or large ones such as cobras. They have been known to dig up human corpses in India. They devour all parts of their prey, including skin, hair, feathers, flesh and bones, holding their food down with their forepaws. When seeking vegetable food, they lift stones or tear bark from trees.
The Range of a Honey Badger
The species ranges through most of sub-Saharan Africa, from the Western Cape, South Africa, to southern Morocco and southwestern Algeria and outside Africa through Arabia, Iran and western Asia to Turkmenistan and the Indian Peninsula. It is known to range from sea level to as much as 2,600 m above sea level in the Moroccan High Atlas and 4,000 m in Ethiopia’s Bale Mountains.
