Systems and Methods for Fabricating Structures Including Metallic Glass-Based Materials Using Low Pressure Casting

Systems and methods to fabricate objects including metallic glass-based materials using low-pressure casting techniques are described. In one embodiment, a method of fabricating an object that includes a metallic glass-based material includes: introducing molten alloy into a mold cavity defined by a mold using a low enough pressure such that the molten alloy does not conform to features of the mold cavity that are smaller than 100 microns; and cooling the molten alloy such that it solidifies, the solid including a metallic glass-based material

Design of a pneumatically assisted shifting system for Formula SAE® racing applications

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2008.Includes bibliographical references (leaf 42).An improved shifting system for use with the MIT Formula SAE race car was designed in order to provide drivers with a faster and easier means of shifting. The result of this design was a pneumatic shifting system weighing just 3.6 pounds and capable of shifting the car's transmission in 200ms (downshifts are slightly slower because they require the use of the clutch). Shifts are initiated through buttons on the steering wheel and controlled through the car's engine control processor. An ergonomic clutch was also designed in order to help shift more easily and provide more control of the vehicle. This document describes, from beginning to end, the design process involved in creating these systems and provides justification for each decision that was made along the way.by Andrew J. Kennett.S.B

Imported Case of Poliomyelitis, Melbourne, Australia, 2007

Wild poliovirus–associated paralytic poliomyelitis has not been reported in Australia since 1977. We report type 1 wild poliovirus infection in a man who had traveled from Pakistan to Australia in 2007. Poliomyelitis should be considered for patients with acute flaccid paralysis or unexplained fever who have been to poliomyelitis-endemic countries

Castable Bulk Metallic Glass Strain Wave Gears: Towards Decreasing the Cost of High-Performance Robotics

The use of bulk metallic glasses (BMGs) as the flexspline in strain wave gears (SWGs), also known as harmonic drives, is presented. SWGs are unique, ultra-precision gearboxes that function through the elastic flexing of a thin-walled cup, called a flexspline. The current research demonstrates that BMGs can be cast at extremely low cost relative to machining and can be implemented into SWGs as an alternative to steel. This approach may significantly reduce the cost of SWGs, enabling lower-cost robotics. The attractive properties of BMGs, such as hardness, elastic limit and yield strength, may also be suitable for extreme environment applications in spacecraft

The Short-Term Effect of Video Editing Pace on Children’s Inhibition and N2 and P3 ERP Components during Visual Go/No-Go Task

We investigated the immediate consequences of differently paced videos on behaviour and neural activity during response inhibition. Forty 7-year-olds watched a fast- or slow-paced video and completed a go/no-go task. Compared to the slow-paced-video group, children in the fast-paced-video group made more no-go errors. There was also an interaction between pace and no-go response type (correct, wrong) for the N2 and P3 peak latencies. In the slow-paced group, both components peaked earlier for correct response withholds. This usual pattern of activation was absent in the fast-paced group. Video pace appears to affect behaviour and the neural responses involved in inhibition

Discovery of a nanodiamond-rich layer in the Greenland ice sheet

We report the discovery in the Greenland ice sheet of a discrete layer of free nanodiamonds (NDs) in very high abundances, implying most likely either an unprecedented influx of extraterrestrial (ET) material or a cosmic impact event that occurred after the last glacial episode. From that layer, we extracted n-diamonds and hexagonal diamonds (lonsdaleite), an accepted ET impact indicator, at abundances of up to about 5!106 times background levels in adjacent younger and older ice. The NDs in the concentrated layer are rounded, suggesting they most likely formed during a cosmic impact through some process similar to carbon-vapor deposition or high-explosive detonation. This morphology has not been reported previously in cosmic material, but has been observed in terrestrial impact material. This is the first highly enriched, discrete layer of NDs observed in glacial ice anywhere, and its presence indicates that ice caps are important archives of ET events of varying magnitudes. Using a preliminary ice chronology based on oxygen isotopes and dust stratigraphy, the ND-rich layer appears to be coeval with ND abundance peaks reported at numerous North American sites in a sedimentary layer, the Younger Dryas boundary layer (YDB), dating to 12.9 0.1 ka. However, more investigation is needed to confirm this association

Climate Change and invasibility of the Antarctic benthos

Benthic communities living in shallow-shelf habitats in Antarctica (<100-m depth) are archaic in their structure and function. Modern predators, including fast-moving, durophagous (skeleton-crushing) bony fish, sharks, and crabs, are rare or absent; slow-moving invertebrates are the top predators; and epifaunal suspension feeders dominate many soft substratum communities. Cooling temperatures beginning in the late Eocene excluded durophagous predators, ultimately resulting in the endemic living fauna and its unique food-web structure. Although the Southern Ocean is oceanographically isolated, the barriers to biological invasion are primarily physiological rather than geographic. Cold temperatures impose limits to performance that exclude modern predators. Global warming is now removing those physiological barriers, and crabs are reinvading Antarctica. As sea temperatures continue to rise, the invasion of durophagous predators will modernize the shelf benthos and erode the indigenous character of marine life in Antarctica

The Neural Basis of Somatosensory Remapping Develops in Human Infancy

When we sense a touch, our brains take account of our current limb position to determine the location of that touch in external space [1, 2]. Here we show that changes in the way the brain processes somatosensory information in the first year of life underlie the origins of this ability [3]. In three experiments we recorded somatosensory evoked potentials (SEPs) from 6.5-, 8-, and 10-month-old infants while presenting vibrotactile stimuli to their hands across uncrossed- and crossed-hands postures. At all ages we observed SEPs over central regions contralateral to the stimulated hand. Somatosensory processing was influenced by arm posture from 8 months onward. At 8 months, posture influenced mid-latency SEP components, but by 10 months effects were observed at early components associated with feed-forward stages of somatosensory processing. Furthermore, sight of the hands was a necessary pre-requisite for somatosensory remapping at 10 months. Thus, the cortical networks [4] underlying the ability to dynamically update the location of a perceived touch across limb movements become functional during the first year of life. Up until at least 6.5 months of age, it seems that human infants’ perceptions of tactile stimuli in the external environment are heavily dependent upon limb position