4,330 research outputs found

    The bichrome test: Comparing the use of lights as stimulus targets to the use of shadows

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    The standard bichrome·(duochrome) test consists of using black letters with a red and 9reen background. The patient is asked. to distinguish the less blurry or more clear letters and therefore uses central fixation to distinguish black letters and an off foveal area to detect red and green. This may contribute to insensitivity to the test and inaccurate spherical findings. The traditional method was compared with a second method in which the letters are red and green and the background is black. The latter was found to be a viable alternative that is more sensitive than the standard test

    Neuromuscular control of wingbeat kinematics in Anna's hummingbirds (Calypte anna)

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    Hummingbirds can maintain the highest wingbeat frequencies of any flying vertebrate – a feat accomplished by the large pectoral muscles that power the wing strokes. An unusual feature of these muscles is that they are activated by one or a few spikes per cycle as revealed by electromyogram recordings (EMGs). The relatively simple nature of this activation pattern provides an opportunity to understand how motor units are recruited to modulate limb kinematics. Hummingbirds made to fly in low-density air responded by moderately increasing wingbeat frequency and substantially increasing the wing stroke amplitude as compared with flight in normal air. There was little change in the number of spikes per EMG burst in the pectoralis major muscle between flight in normal and low-density heliox (mean=1.4 spikes cycle^(–1)). However the spike amplitude, which we take to be an indication of the number of active motor units, increased in concert with the wing stroke amplitude, 1.7 times the value in air. We also challenged the hummingbirds using transient load lifting to elicit maximum burst performance. During maximum load lifting, both wing stroke amplitude and wingbeat frequency increased substantially above those values during hovering flight. The number of spikes per EMG burst increased to a mean of 3.3 per cycle, and the maximum spike amplitude increased to approximately 1.6 times those values during flight in heliox. These results suggest that hummingbirds recruit additional motor units (spatial recruitment) to regulate wing stroke amplitude but that temporal recruitment is also required to maintain maximum stroke amplitude at the highest wingbeat frequencies

    Evaluation of SMAP Freeze/Thaw Retrieval Accuracy at Core Validation Sites in the Contiguous United States

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    Seasonal freeze-thaw (FT) impacts much of the northern hemisphere and is an important control on its water, energy, and carbon cycle. Although FT in natural environments extends south of 45°N, FT studies using the L-band have so far been restricted to boreal or greater latitudes. This study addresses this gap by applying a seasonal threshold algorithm to Soil Moisture Active Passive (SMAP) data (L3_SM_P) to obtain a FT product south of 45°N (‘SMAP FT’), which is then evaluated at SMAP core validation sites (CVS) located in the contiguous United States (CONUS). SMAP landscape FT retrievals are usually in good agreement with 0–5 cm soil temperature at SMAP grids containing CVS stations (\u3e70%). The accuracy could be further improved by taking into account specific overpass time (PM), the grid-specific seasonal scaling factor, the data aggregation method, and the sampling error. Annual SMAP FT extent maps compared to modeled soil temperatures derived from the Goddard Earth Observing System Model Version 5 (GEOS-5) show that seasonal FT in CONUS extends to latitudes of about 35–40°N, and that FT varies substantially in space and by year. In general, spatial and temporal trends between SMAP and modeled FT were similar

    CD9, a Major Platelet Cell Surface Glycoprotein, is a ROCA Antigen and Is Expressed in the Nervous System

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    We previously generated a monoclonal antibody (mAb), ROCA1, which binds preferentially to rostral versus caudal sympathetic ganglia and intercostal nerves. Two other mAbs, ROCA2 and B2C11, bind to the same structures but not in rostrocaudal gradients. All three mAbs recognize a 26 kDa cell surface protein. Amino acid sequence data obtained from the affinity purified 26 kDa protein showed some homology with human CD9, a tetraspan protein implicated in intercellular signaling in hematopoietic cells. Using the PCR, we obtained cDNA clones representing the entire rat CD9 coding sequence from sciatic nerve and sympathetic ganglia. ROCA1, ROCA2, and B2C11 each immunoprecipitate a 26 kDa protein from CHO cells stably transfected with one of the clones, demonstrating that the ROCA cell surface antigen is indeed rat CD9. We find that CD9 mRNA is widely expressed, with particularly high levels present in a number of neural tissues. In situ hybridization demonstrates that peripheral neurons and Schwann cells, as well as adrenal chromaffin cells express CD9 mRNA. Consistent with immunoblot analyses showing that, unlike the ROCA1 epitope, the 26 kDa protein is not expressed in a rostrocaudal gradient, we find similar levels of rat CD9 mRNA in rostral and caudal intercostal nerves. In developing postnatal rat sciatic nerve, CD9 mRNA levels are coordinately regulated with the expression of myelin genes. These results provide another example of a cell surface protein expressed by both hematopoietic and neural cells, and suggest a role for CD9 in intercellular signaling in the nervous system

    Abelian Dominance in Wilson Loops

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    It has been conjectured that the Abelian projection of QCD is responsible for the confinement of color. Using a gauge independent definition of the Abelian projection which does {\it not} employ any gauge fixing, we provide a strong evidence for the Abelian dominance in Wilson loop integral. In specific we prove that the gauge potential which contributes to the Wilson loop integral is precisely the one restricted by the Abelian projection.Comment: 4 pages, no figure, revtex. Phys. Rev. D in pres

    Private Enforcement of NAFTA Environmental Standards through Transnational Mass Tort Litigation: The Role of United States Courts in the Age of Free Trade Symposium - The Environment and the United States-Mexico Border - Comment.

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    Maquiladoras are manufacturing facilities along the United States-Mexico border operated by transnational corporations (TNCs). The arrival of the North American Free Trade Agreement (NAFTA) meant TNCs are free to move capital and operations across the United States-Mexico border at will. Yet, the maquiladora workers are not free to travel or seek employment across the border. The NAFTA debate in the United States raised public awareness of environmental problems in the border region. Nevertheless, maquiladora workers have lived with environmental degradation long before the NAFTA environmental debate began. With the passage of NAFTA, increased trade and the burgeoning industries along the border are likely to exacerbate already serious environmental problems. The question of a foreign plaintiff’s freedom to choose a jurisdiction in which to sue for injuries resulting from environmental pollution is complicated by the questions of public policy and forum non conveniens considerations. Courts must weigh the interests of the United States government and citizens in resolving claims arising from injuries suffered by a Mexican plaintiff in Mexico. When United States courts face environmental tort claims brought by NAFTA nationals, the traditional forum non conveniens doctrine does not seem to fit or serve any meaningful policy goals. A better approach is the abolition of the forum non convenience doctrine. Such an abolition would eliminate any ambiguity regarding the accessibility of the United States courts to exploited workers and residents of a “free trade partner country,” and provide the most effective deterrence to future abuses and exploitation. In an age where national borders are practically removed for TNCs but still remain a solid wall to the citizens of different nations, the “judicial border” of forum non conveniens erected against maquiladora workers not only loses its logical justifications, it also works against the interest of the United States public as well

    Deep Thermal Imaging: Proximate Material Type Recognition in the Wild through Deep Learning of Spatial Surface Temperature Patterns

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    We introduce Deep Thermal Imaging, a new approach for close-range automatic recognition of materials to enhance the understanding of people and ubiquitous technologies of their proximal environment. Our approach uses a low-cost mobile thermal camera integrated into a smartphone to capture thermal textures. A deep neural network classifies these textures into material types. This approach works effectively without the need for ambient light sources or direct contact with materials. Furthermore, the use of a deep learning network removes the need to handcraft the set of features for different materials. We evaluated the performance of the system by training it to recognise 32 material types in both indoor and outdoor environments. Our approach produced recognition accuracies above 98% in 14,860 images of 15 indoor materials and above 89% in 26,584 images of 17 outdoor materials. We conclude by discussing its potentials for real-time use in HCI applications and future directions.Comment: Proceedings of the 2018 CHI Conference on Human Factors in Computing System

    Meconium in the Amniotic Fluid of Pregnancies Complicated by Preterm Premature Rupture of Membranes Is Associated With Early Onset Neonatal Sepsis

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    Objective: This study was to determine the significance of meconium in the amniotic fluid of pregnancies complicated by preterm premature rupture of membranes (PPROM) without labor
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