Mesoscopic scattering in the half-plane: squeezing conductance through a small hole

We model the 2-probe conductance of a quantum point contact (QPC), in linear response. If the QPC is highly non-adiabatic or near to scatterers in the open reservoir regions, then the usual distinction between leads and reservoirs breaks down and a technique based on scattering theory in the full two-dimensional half-plane is more appropriate. Therefore we relate conductance to the transmission cross section for incident plane waves. This is equivalent to the usual Landauer formula using a radial partial-wave basis. We derive the result that an arbitrarily small (tunneling) QPC can reach a p-wave channel conductance of 2e^2/h when coupled to a suitable reflector. If two or more resonances coincide the total conductance can even exceed this. This relates to recent mesoscopic experiments in open geometries. We also discuss reciprocity of conductance, and the possibility of its breakdown in a proposed QPC for atom waves.Comment: 8 pages, 3 figures, REVTeX. Revised version (shortened), accepted for publication in PR

Number, Density, and Surface/Cytoplasmic Distribution of GABA Transporters at Presynaptic Structures of Knock-In Mice Carrying GABA Transporter Subtype 1–Green Fluorescent Protein Fusions

GABA transporter subtype 1 (GAT1) molecules were counted near GABAergic synapses, to a resolution of ∼0.5 μm. Fusions between GAT1 and green fluorescent protein (GFP) were tested in heterologous expression systems, and a construct was selected that shows function, expression level, and trafficking similar to that of wild-type (WT) GAT1. A strain of knock-in mice was constructed that expresses this mGAT1–GFP fusion in place of the WT GAT1 gene. The pattern of fluorescence in brain slices agreed with previous immunocytochemical observations. [^3H]GABA uptake, synaptic electrophysiology, and subcellular localization of the mGAT1–GFP construct were also compared with WT mice. Quantitative fluorescence microscopy was used to measure the density of mGAT1–GFP at presynaptic structures in CNS preparations from the knock-in mice. Fluorescence measurements were calibrated with transparent beads and gels that have known GFP densities. Surface biotinylation defined the fraction of transporters on the surface versus those in the nearby cytoplasm. The data show that the presynaptic boutons of GABAergic interneurons in cerebellum and hippocampus have a membrane density of 800–1300 GAT1 molecules per square micrometer, and the axons that connect boutons have a linear density of 640 GAT1 molecules per micrometer. A cerebellar basket cell bouton, a pinceau surrounding a Purkinje cell axon, and a cortical chandelier cell cartridge carry 9000, 7.8 million, and 430,000 GAT1 molecules, respectively; 61–63% of these molecules are on the surface membrane. In cultures from hippocampus, the set of fluorescent cells equals the set of GABAergic interneurons. Knock-in mice carrying GFP fusions of membrane proteins provide quantitative data required for understanding the details of synaptic transmission in living neurons

Number, Density, and Surface/Cytoplasmic Distribution of GABA Transporters at Presynaptic Structures of Knock-In Mice Carrying GABA Transporter Subtype 1–Green Fluorescent Protein Fusions

GABA transporter subtype 1 (GAT1) molecules were counted near GABAergic synapses, to a resolution of ∼0.5 μm. Fusions between GAT1 and green fluorescent protein (GFP) were tested in heterologous expression systems, and a construct was selected that shows function, expression level, and trafficking similar to that of wild-type (WT) GAT1. A strain of knock-in mice was constructed that expresses this mGAT1–GFP fusion in place of the WT GAT1 gene. The pattern of fluorescence in brain slices agreed with previous immunocytochemical observations. [^3H]GABA uptake, synaptic electrophysiology, and subcellular localization of the mGAT1–GFP construct were also compared with WT mice. Quantitative fluorescence microscopy was used to measure the density of mGAT1–GFP at presynaptic structures in CNS preparations from the knock-in mice. Fluorescence measurements were calibrated with transparent beads and gels that have known GFP densities. Surface biotinylation defined the fraction of transporters on the surface versus those in the nearby cytoplasm. The data show that the presynaptic boutons of GABAergic interneurons in cerebellum and hippocampus have a membrane density of 800–1300 GAT1 molecules per square micrometer, and the axons that connect boutons have a linear density of 640 GAT1 molecules per micrometer. A cerebellar basket cell bouton, a pinceau surrounding a Purkinje cell axon, and a cortical chandelier cell cartridge carry 9000, 7.8 million, and 430,000 GAT1 molecules, respectively; 61–63% of these molecules are on the surface membrane. In cultures from hippocampus, the set of fluorescent cells equals the set of GABAergic interneurons. Knock-in mice carrying GFP fusions of membrane proteins provide quantitative data required for understanding the details of synaptic transmission in living neurons

Ancestral roles of the Fam20C family of secreted protein kinases revealed in C. elegans.

Fam20C is a secreted protein kinase mutated in Raine syndrome, a human skeletal disorder. In vertebrates, bone and enamel proteins are major Fam20C substrates. However, Fam20 kinases are conserved in invertebrates lacking bone and enamel, suggesting other ancestral functions. We show that FAMK-1, the Caenorhabditis elegans Fam20C orthologue, contributes to fertility, embryogenesis, and development. These functions are not fulfilled when FAMK-1 is retained in the early secretory pathway. During embryogenesis, FAMK-1 maintains intercellular partitions and prevents multinucleation; notably, temperature elevation or lowering cortical stiffness reduces requirement for FAMK-1 in these contexts. FAMK-1 is expressed in multiple adult tissues that undergo repeated mechanical strain, and selective expression in the spermatheca restores fertility. Informatic, biochemical, and functional analysis implicate lectins as FAMK-1 substrates. These findings suggest that FAMK-1 phosphorylation of substrates, including lectins, in the late secretory pathway is important in embryonic and tissue contexts where cells are subjected to mechanical strain

Recurrent hospitalization and healthcare resource use among patients with deep vein thrombosis and pulmonary embolism: findings from a multi-payer analysis

The objective of this study was to assess deep vein thrombosis and pulmonary embolism (DVT/PE) recurrence rates and resource utilization among patients with an initial DVT or PE event across multiple payer perspectives. Retrospective analyses were performed using a software tool that analyzes health plan claims to evaluate treatment patterns and resource utilization for various cardiovascular conditions. Six databases were analyzed from three payer perspectives (Commercial, Medicare, and Medicaid). Patients were ≥18 years old with a primary diagnosis of DVT or PE associated with an inpatient and/or emergency room claim, had received an antithrombotic within 7 days before or 14 days after index, and had no diagnosis of atrial fibrillation during follow-up. Outcomes were assessed over a 1 year period following index. More PE patients were hospitalized for their index event than DVT patients (42–59 % DVT and 69–86 % PE) and had longer mean length of stay (2.35–2.95 days DVT and 3.26–3.76 days PE). Recurrent event rates among PE patients (12–32 %) were higher than those for DVT patients (6–16 %) across all payers. The highest rate of recurrence was observed among the Medicaid population [23 % overall (VTE); 16 % DVT; 32 % PE]. All-cause hospitalization in the year following their VTE episode occurred in 23–67 % DVT patients and 30–68 % PE patients. Medicaid had the highest proportion of patients with hospitalizations and ER visits. Recurrent VTE events and all-cause hospitalizations are relatively common, especially for patients who had a PE, and among those in the Medicaid payer population

Managing occupational hazards confronting healthcare workers

The primary goal of this thesis is to identify, evaluate, and control occupational hazards that may exist in health care facilities. Due to the complex nature of health care facilities, healthcare workers are always challenged by an imposing group of occupational hazards. The magnitude and diversity of these hazards, and the constantly changing nature of government regulations make it difficult to guarantee absolute protection and accuracy of the material contained herein. However, awareness of the risks, compliance with basic preventive measures, and adequate interventions are all essential components to consider in protecting healthcare workers. Therefore, potential health effects of various hazards such as back injuries, heat, noise, infectious hazards, pharmaceutical hazards, chemicals, exposure to radiation, and prevalent psychosocial (stress) problems are reviewed, and rational approaches to managing and preventing these problems are offered. This thesis also presents a broad overview of hospital safety programs, and job safety analyses; it offers assistance in understanding and complying with regulations and guidelines issued by the Centers for Disease Control and Prevention (CDC), the Occupational Safety and Health Administration (OSHA), the National Institute for Occupational Safety and Health (NIOSH), and the Joint Commission on Accreditation of Healthcare Organizations (JCAHO)

The determinants of vulnerability to currency crises: country-specific factors versus regional factors

We investigate the determinants of exchange market pressures (EMP) for some new EU member states at both the national and regional levels, where macroeconomic and financial variables are considered as potential sources. The regional common factors are extracted from these variables by using dynamic factor analysis. The linear empirical analysis, in general, highlights the importance of country-specific factors to defend themselves against vulnerability in their external sectors. Yet, given a significant impact of the common component in credit on EMP, a contagion effect is apparent through the conduit of credit market integration across these countries under investigation

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New therapeutic alternatives to treat Acute Bacterial Skin and Skin Structure Infections (ABSSI