113 research outputs found

    Fabrication of minority-carrier-limited n-Si/insulator/metal diodes

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    A photoelectrochemical anodization technique has been used to fabricate n-Si/insulator/metal (MIS) diodes with improved electrical properties. MIS structures fabricated with Au have provided the first experimental observation of a solid-state n-Si surface barrier device whose open circuit voltage Voc is controlled by minority-carrier bulk diffusion/recombination processes. For these diodes, variation of the minority-carrier diffusion length and majority-carrier dopant density produced changes in Voc that were in accord with bulk diffusion/recombination theory. Additionally, the variation in Voc in response to changes in the work function of the metal overlayer indicated that these MIS devices were not subject to the Fermi level pinning restrictions observed for n-Si Schottky structures. X-ray photoelectron spectroscopic characterization of the anodically grown insulator indicated 8.2±0.9 Å of a strained SiO2 layer as the interfacial insulator resulting from the photoanodization process

    Neurocytoma in the cerebellum: Case report

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    A neurocytoma is a central nervous system tumor composed of small cells with features of neuronal differentiation; it typically occurs in the periventricular region, close to the septum pellucidum and the foramen of Monro. In this article, the authors report the case of a neurocytoma located in the cerebellum, which to their knowledge is the first reported case of its kind. The finding of a neurocytoma at a nonclassic location refutes the theory that this tumor has its origins in subependymal progenitor cells, unless an ectopic location of progenitor cells is invoked to explain the occurrence of a neurocytoma away from the ventricles. On the basis of this case, the authors suggest that neurocytomas should be added to the differential diagnosis of mass lesions in the supratentorial intraventricular regions as well as in the posterior fossa

    Conus Medullaris Enterogenous Cyst

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/147142/1/pmr2698.pd

    Sustained Reduction of Diversion and Abuse after Introduction of an Abuse Deterrent Formulation of Extended Release Oxycodone

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    Background: The development of abuse deterrent formulations is one strategy for reducing prescription opioid misuse and abuse. A putative abuse deterrent formulation of oxycodone extended release (OxyContin®) was introduced in 2010. Early reports demonstrated reduced abuse and diversion, however, an analysis of social media found 32 feasible methods to circumventthe abuse deterrent mechanism. We measured trends of diversion, abuse and street price of OxyContin to assess the durability ofthe initial reduction in abuse. Methods: Data from the Poison Center Program, Drug Diversion Program, Opioid Treatment Program, Survey of Key Informant Patients Program and StreetRx program of the Researched Abuse, Diversion, and Addiction-Related Surveillance (RADARS®) System were used. The average quarterly rates of abuse and diversion for OxyContin were compared from before reformulation to the rate in second quarter 2015. Rates were adjusted for population using US Census data and drug availability. Results: OxyContin abuse and diversion declined significantly each quarter after reformulation and persisted for 5 years. The rate of abuse of other opioid analgesics increased initially and then decreased, but to lesser extent than OxyContin. Abuse through both oral and non-oral routes of self-administration declined following the reformulation. The geometric mean difference in the street price of reformulated OxyContin was 36% lower than the reformulated product in the year after reformulation. Discussion: Despite methods to circumvent the abuse deterrent mechanism, abuse and diversion of OxyContin decreased promptly following the introduction of a crush- and solubility- resistant formulation and continued to decrease over the subsequent 5 years

    Context-dependent conservation responses to emerging wildlife diseases

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    Emerging infectious diseases pose an important threat to wildlife. While established protocols exist for combating outbreaks of human and agricultural pathogens, appropriate management actions before, during, and after the invasion of wildlife pathogens have not been developed. We describe stage-specific goals and management actions that minimize disease impacts on wildlife, and the research required to implement them. Before pathogen arrival, reducing the probability of introduction through quarantine and trade restrictions is key because prevention is more cost effective than subsequent responses. On the invasion front, the main goals are limiting pathogen spread and preventing establishment. In locations experiencing an epidemic, management should focus on reducing transmission and disease, and promoting the development of resistance or tolerance. Finally, if pathogen and host populations reach a stable stage, then recovery of host populations in the face of new threats is paramount. Successful management of wildlife disease requires risk-taking, rapid implementation, and an adaptive approach."Funding was provided by the US National Science Foundation (grants EF-0914866, DGE-0741448, DEB-1115069, DEB-1336290) and the National Institutes of Health (grant 1R010AI090159)."https://esajournals.onlinelibrary.wiley.com/doi/abs/10.1890/14024

    Segmentation of corpus callosum using diffusion tensor imaging: validation in patients with glioblastoma

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    Abstract Background This paper presents a three-dimensional (3D) method for segmenting corpus callosum in normal subjects and brain cancer patients with glioblastoma. Methods Nineteen patients with histologically confirmed treatment naïve glioblastoma and eleven normal control subjects underwent DTI on a 3T scanner. Based on the information inherent in diffusion tensors, a similarity measure was proposed and used in the proposed algorithm. In this algorithm, diffusion pattern of corpus callosum was used as prior information. Subsequently, corpus callosum was automatically divided into Witelson subdivisions. We simulated the potential rotation of corpus callosum under tumor pressure and studied the reproducibility of the proposed segmentation method in such cases. Results Dice coefficients, estimated to compare automatic and manual segmentation results for Witelson subdivisions, ranged from 94% to 98% for control subjects and from 81% to 95% for tumor patients, illustrating closeness of automatic and manual segmentations. Studying the effect of corpus callosum rotation by different Euler angles showed that although segmentation results were more sensitive to azimuth and elevation than skew, rotations caused by brain tumors do not have major effects on the segmentation results. Conclusions The proposed method and similarity measure segment corpus callosum by propagating a hyper-surface inside the structure (resulting in high sensitivity), without penetrating into neighboring fiber bundles (resulting in high specificity)

    Resection of Multiple Nocardial Brain Abscesses

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    Invasion in malignant glioma

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