845 research outputs found
Cryogenic Orbital Nitrogen Experiment (CONE): Phase A/B design study
Subcritical cryogenic fluid management (CFM) has long been recognized as an enabling technology for future space missions. Subcritical liquid storage and supply are two of the five CFM technology areas that need to be studied in the low gravity on-orbit environment. The Cryogenic Orbital Nitrogen Experiment (CONE) is a LN2 cryogenic storage and supply system demonstration placed in orbit by the National Space Transportation System (NSTS) Orbiter and operated as an in-bay payload. In-space demonstration of CFM using LN2 with a few well defined areas of focus would provide the confidence level required to implement subcritical cryogen use and is the first step towards the more far reaching issue of cryogen transfer and tankage resupply. A conceptual approach for CONE was developed and an overview of the program is described including the following: (1) a description of the background and scope of the technology objectives; (2) a description of the payload design and operation; and (3) the justification for CONE relating to potential near term benefits and risk mitigation for future systems. Data and criteria is provided to correlate in-space performance with analytical and numerical modeling of CFM systems
Distinct Retinohypothalamic Innervation Patterns Predict the Developmental Emergence of Species-typical Circadian Phase Preference in Nocturnal Norway Rats and Diurnal Nile Grass Rats
How does the brain develop differently to support nocturnality in some mammals, but diurnality in others? To answer this question, one might look to the suprachiasmatic nucleus (SCN), which is entrained by light via the retinohypothalamic tract (RHT). However, because the SCN is more active during the day in all mammals studied thus far, it alone cannot determine circadian phase preference. In adult Norway rats (Rattus norvegicus), which are nocturnal, the RHT also projects to the ventral subparaventricular zone (vSPVZ), an adjacent region that expresses an in-phase pattern of SCN-vSPVZ neuronal activity. In contrast, in adult Nile grass rats (Arvicanthis niloticus), which are diurnal, an anti-phase pattern of SCN-vSPVZ neuronal activity is expressed. We hypothesized that these species differences result in part from a weak or absent RHT-to-vSPVZ projection in grass rats. Here, using a developmental comparative approach, we assessed species differences in behavior, hypothalamic activity, and RHT anatomy. We report that a robust retina-to-vSPVZ projection develops in Norway rats around the end of the second postnatal week when nocturnal wakefulness and the in-phase pattern of neuronal activity emerge. In grass rats, however, such a projection does not develop and the emergence of the anti-phase pattern during the second postnatal week is accompanied by increased diurnal wakefulness. When considered within the context of previously published reports on RHT projections in a variety of species, the current findings suggest that how and when the retina connects to the hypothalamus differentially shapes brain and behavior to produce animals that occupy opposing temporal niches
Quantum optical microcombs
A key challenge for quantum science and technology is to realize large-scale, precisely controllable, practical systems for non-classical secured communications, metrology and, ultimately, meaningful quantum simulation and computation. Optical frequency combs represent a powerful approach towards this goal, as they provide a very high number of temporal and frequency modes that can result in large-scale quantum systems. The generation and control of quantum optical frequency combs will enable a unique, practical and scalable framework for quantum signal and information processing. Here, we review recent progress on the realization of energy–time entangled optical frequency combs and discuss how photonic integration and the use of fibre-optic telecommunications components can enable quantum state control with new functionalities, yielding unprecedented capability
Psychogenic dystonia and peripheral trauma
ABSTRACT Dystonia in association with peripheral trauma is a well-described clinical syndrome. The syndrome goes by many names-"traumatic" dystonia, "fixed" dystonia, peripherally induced dystonia, or complex region pain syndrome (CRPS) dystonia. We reviewed the role of peripheral trauma in the development of dystonia, focusing on 4 subtypes-cervical dystonia, focal limb dystonia, CRPS dystonia, and psychogenic dystonia. We show that peripheral trauma inducing, provoking, or precipitating structural changes within the CNS leading to dystonia is not an accepted concept, and current evidence supporting a pathophysiologic mechanism is virtually nonexistent. A better approach to this clinical syndrome is to define it as fixed abnormal posturing that is most commonly psychogenic. While symptomatic treatment of pain and spasms with medication can be beneficial, early psychological evaluation and patient-specific treatment is important. Modalities such as physical and occupational therapy should be utilized early. Finally, it should be emphasized that like many psychogenic movement disorders, it remains a highly disabling and distressing disorder. Neurology ® 2011;77:496-50
An Actin-Based Wave Generator Organizes Cell Motility
Although many of the regulators of actin assembly are known, we do not understand how these components act together to organize cell shape and movement. To address this question, we analyzed the spatial dynamics of a key actin regulator—the Scar/WAVE complex—which plays an important role in regulating cell shape in both metazoans and plants. We have recently discovered that the Hem-1/Nap1 component of the Scar/WAVE complex localizes to propagating waves that appear to organize the leading edge of a motile immune cell, the human neutrophil. Actin is both an output and input to the Scar/WAVE complex: the complex stimulates actin assembly, and actin polymer is also required to remove the complex from the membrane. These reciprocal interactions appear to generate propagated waves of actin nucleation that exhibit many of the properties of morphogenesis in motile cells, such as the ability of cells to flow around barriers and the intricate spatial organization of protrusion at the leading edge. We propose that cell motility results from the collective behavior of multiple self-organizing waves
Cryogenic On-Orbit Liquid Depot Storage, Acquisition, and Transfer satellite (COLD-SAT) feasibility study
The Cryogenic On-Orbit Liquid Depot Storage, Acquisition, and Transfer Satellite (COLD-SAT) is an experimental spacecraft launched from an expendable launch vehicle which is designed to investigate the systems and technologies required for efficient, effective, and reliable management of cryogenic fluid in the reduced gravity space environment. The COLD-SAT program will provide the necessary data base and provide low-g proving of fluid and thermal models of cryogenic storage, transfer, and resupply concepts and processes. A conceptual approach was developed and an overview of the results of the 24 month COLD-SAT Phase A feasibility is described which includes: (1) a definition of the technology needs and the accompanying experimental 3 month baseline mission; (2) a description of the experiment subsystem, major features and rationale for satisfaction of primary and secondary experiment requirements using liquid hydrogen as the test fluid; and (3) a presentation of the conceptual design of the COLD-SAT spacecraft subsystems which support the on-orbit experiment with emphasis on areas of greatest challenge
Criteria for the diagnosis of corticobasal degeneration
Current criteria for the clinical diagnosis of pathologically confirmed corticobasal degeneration (CBD) no longer reflect the expanding understanding of this disease and its clinicopathologic correlations. An international consortium of behavioral neurology, neuropsychology, and movement disorders specialists developed new criteria based on consensus and a systematic literature review. Clinical diagnoses (early or late) were identified for 267 nonoverlapping pathologically confirmed CBD cases from published reports and brain banks. Combined with consensus, 4 CBD phenotypes emerged: corticobasal syndrome (CBS), frontal behavioral-spatial syndrome (FBS), nonfluent/agrammatic variant of primary progressive aphasia (naPPA), and progressive supranuclear palsy syndrome (PSPS). Clinical features of CBD cases were extracted from descriptions of 209 brain bank and published patients, providing a comprehensive description of CBD and correcting common misconceptions. Clinical CBD phenotypes and features were combined to create 2 sets of criteria: more specific clinical research criteria for probable CBD and broader criteria for possible CBD that are more inclusive but have a higher chance to detect other tau-based pathologies. Probable CBD criteria require insidious onset and gradual progression for at least 1 year, age at onset ≥50 years, no similar family history or known tau mutations, and a clinical phenotype of probable CBS or either FBS or naPPA with at least 1 CBS feature. The possible CBD category uses similar criteria but has no restrictions on age or family history, allows tau mutations, permits less rigorous phenotype fulfillment, and includes a PSPS phenotype. Future validation and refinement of the proposed criteria are needed
Effect of state-mandated insurance coverage on accrual to community cancer clinical trials
Thirty-five U.S. states and territories have implemented policies requiring insurers to cover patient care costs in the context of cancer clinical trials; however, evidence of the effectiveness of these policies is limited. This study assesses the impact of state insurance mandates on clinical trial accrual among community-based practices participating in the NCI Community Clinical Oncology Program (CCOP), which enrolls approximately one-third of all NCI cancer trial participants. We analyzed CCOP clinical trial enrollment over 17 years in 37 states, 14 of which implemented coverage policies, using fixed effects least squares regression to estimate the effect of state policies on trial accrual among community providers, controlling for state and CCOP differences in capacity to recruit. Of 91 CCOPs active during this time, 28 were directly affected by coverage mandates. Average recruitment per CCOP between 1991 and 2007 was 95.1 participants per year (SD = 55.8). CCOPs in states with a mandate recruited similar numbers of participants compared to states without a mandate. In multivariable analysis, treatment trial accrual among CCOPs in states that had implemented a coverage mandate, was not statistically different than accrual among CCOPs in states that did not implement a coverage mandate (β = 2.95, p = 0.681). State mandates did not appear to confer a benefit in terms of CCOP clinical trial accrual. State policies vary in strength, which may have diluted their effect on accrual. Nonetheless, policy mandates alone may not have a meaningful impact on participation in clinical trials in these states
A mathematical model to describe drug release from thin topical applications
Release of a thin topical application of a drug is modeled by transient diffusion between the application, the underlying stratum corneum, and a receptor. Cases treated include sudden contact of the application with drug-free stratum corneum, and initially equilibrated application and stratum corneum. The method of solution is the numerical inversion of the analytic Laplace Transform of the exact solution, which has speed, accuracy and convenience advantages over classical analytical or numerical methods for coupled linear partial differential equations. The algorithm for long-time solutions in the time domain is also found, although this has no computational advantage over the direct numerical transform inversion.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27653/1/0000034.pd
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