572 research outputs found
The Nimbus 4 Infrared Spectroscopy Experiment, IRIS-D. Part 1: Calibrated Thermal Emission Spectra
Calibrated infrared emission spectra of earth and atmosphere using high resolution interferometer spectrophotometer on Nimbus 4 satellit
Vertebral Artery Injury: Case Report and Review of Operative Approaches
Traumatic injury to the upper third of the neck, cephalad to the angle of the mandible, distorts the complexity of normal anatomy and underscores the importance of preoperative arteriography when possible. This report describes the case of a young man who was brought to the Emergency Room of our hospital suffering from a severe gunshot wound to the cervical spine, vertebral artery, and maxillofacial skeleton. His injury was successfully managed by combining a standard arterolateral incision with a procedure that has been described for exposing retro maxillary tumors. This operative technique provided the surgeon with direct access to the injury, controlled the loss of blood, and permitted repair of accompanying pharyngeal and facial injuries. Our report also reviews the technical considerations and pertinent surgical anatomy of this rare combination of Injuries
Lateralization of face processing in the human brain
Are visual face processing mechanisms the same in the left and right cerebral hemispheres? The possibility of such ‘duplicated processing’ seems puzzling in terms of neural resource usage, and we currently lack a precise characterization of the lateral differences in face processing. To address this need, we have undertaken a three-pronged approach. Using functional magnetic resonance imaging, we assessed cortical sensitivity to facial semblance, the modulatory effects of context and temporal response dynamics. Results on all three fronts revealed systematic hemispheric differences. We found that: (i) activation patterns in the left fusiform gyrus correlate with image-level face-semblance, while those in the right correlate with categorical face/non-face judgements. (ii) Context exerts significant excitatory/inhibitory influence in the left, but has limited effect on the right. (iii) Face-selectivity persists in the right even after activity on the left has returned to baseline. These results provide important clues regarding the functional architecture of face processing, suggesting that the left hemisphere is involved in processing ‘low-level’ face semblance, and perhaps is a precursor to categorical ‘deep’ analyses on the right.John Merck FundSimons FoundationJames S. McDonnell FoundationNational Eye Institute (NIH, grant number R21-EY015521
Anion vacancies as a source of persistent photoconductivity in II-VI and chalcopyrite semiconductors
Using first-principles electronic structure calculations we identify the
anion vacancies in II-VI and chalcopyrite Cu-III-VI2 semiconductors as a class
of intrinsic defects that can exhibit metastable behavior. Specifically, we
predict persistent electron photoconductivity (n-type PPC) caused by the oxygen
vacancy VO in n-ZnO, and persistent hole photoconductivity (p-type PPC) caused
by the Se vacancy VSe in p-CuInSe2 and p-CuGaSe2. We find that VSe in the
chalcopyrite materials is amphoteric having two "negative-U" like transitions,
i.e. a double-donor transition e(2+/0) close to the valence band and a
double-acceptor transition e(0/2-) closer to the conduction band. We introduce
a classification scheme that distinguishes two types of defects (e.g., donors):
type-alpha, which have a defect-localized-state (DLS) in the gap, and
type-beta, which have a resonant DLS within the host bands (e.g., conduction
band). In the latter case, the introduced carriers (e.g., electrons) relax to
the band edge where they can occupy a perturbed-host-state (PHS). Type alpha is
non-conducting, whereas type beta is conducting. We identify the neutral anion
vacancy as type-alpha and the doubly positively charged vacancy as type-beta.
We suggest that illumination changes the charge state of the anion vacancy and
leads to a crossover between alpha- and beta-type behavior, resulting in
metastability and PPC. In CuInSe2, the metastable behavior of VSe is carried
over to the (VSe-VCu) complex, which we identify as the physical origin of PPC
observed experimentally. We explain previous puzzling experimental results in
ZnO and CuInSe2 in the light of this model.Comment: submitted to Phys. Rev.
U.S. High Altitude PV Measurement for Primary Calibration Standard Certification
No abstract availabl
A new technique for mandibular osteotomy
Sagittal split osteotomy (SSO) is a surgical technique largely employed for mandibular mobilizations in orthognatic procedures. However, the traditional design of buccal osteotomy, located at the junction of mandibular ramus and body, may prevent more extensive sliding between the bone segments, particularly on the advance, laterality and verticality of the mandibular body. The author proposes a new technical and conceptual solution, in which osteotomy is performed in a more distal region, next to the mental formamen. Technically, the area of contact between medullary-cancellous bone surfaces is increased, resulting in larger sliding rates among bone segments; it also facilitates the use of rigid fixation systems, with miniplates and monocortical screws. Conceptually, it interferes with the resistance arm of the mandible, seen as an interpotent lever of the third gender
A Simple Artificial Life Model Explains Irrational Behavior in Human Decision-Making
Although praised for their rationality, humans often make poor decisions, even in simple situations. In the repeated binary choice experiment, an individual has to choose repeatedly between the same two alternatives, where a reward is assigned to one of them with fixed probability. The optimal strategy is to perseverate with choosing the alternative with the best expected return. Whereas many species perseverate, humans tend to match the frequencies of their choices to the frequencies of the alternatives, a sub-optimal strategy known as probability matching. Our goal was to find the primary cognitive constraints under which a set of simple evolutionary rules can lead to such contrasting behaviors. We simulated the evolution of artificial populations, wherein the fitness of each animat (artificial animal) depended on its ability to predict the next element of a sequence made up of a repeating binary string of varying size. When the string was short relative to the animats’ neural capacity, they could learn it and correctly predict the next element of the sequence. When it was long, they could not learn it, turning to the next best option: to perseverate. Animats from the last generation then performed the task of predicting the next element of a non-periodical binary sequence. We found that, whereas animats with smaller neural capacity kept perseverating with the best alternative as before, animats with larger neural capacity, which had previously been able to learn the pattern of repeating strings, adopted probability matching, being outperformed by the perseverating animats. Our results demonstrate how the ability to make predictions in an environment endowed with regular patterns may lead to probability matching under less structured conditions. They point to probability matching as a likely by-product of adaptive cognitive strategies that were crucial in human evolution, but may lead to sub-optimal performances in other environments
On-Orbit Measurement of Next Generation Space Solar Cell Technology on the International Space Station
Measurement is essential for the evaluation of new photovoltaic (PV) technology for space solar cells. NASA Glenn Research Center (GRC) is in the process of measuring several solar cells in a supplemental experiment on NASA Goddard Space Flight Center's (GSFC) Robotic Refueling Mission's (RRM) Task Board 4 (TB4). Four industry and government partners have provided advanced PV devices for measurement and orbital environment testing. The experiment will be on-orbit for approximately 18 months. It is completely self-contained and will provide its own power and internal data storage. Several new cell technologies including four- junction (4J) Inverted Metamorphic Multijunction (IMM) cells will be evaluated and the results compared to ground-based measurements
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