Accelerated Recovery of Consciousness after General Anesthesia Is Associated with Increased Functional Brain Connectivity in the High-Gamma Bandwidth.

PubMed

Li, Duan; Hambrecht-Wiedbusch, Viviane S; Mashour, George A

2017-01-01

Recent data from our laboratory demonstrate that high-frequency gamma connectivity across the cortex is present during consciousness and depressed during unconsciousness. However, these data were derived from static and well-defined states of arousal rather than during transitions that would suggest functional relevance. We also recently found that subanesthetic ketamine administered during isoflurane anesthesia accelerates recovery upon discontinuation of the primary anesthetic and increases gamma power during emergence. In the current study we re-analyzed electroencephalogram (EEG) data to test the hypothesis that functional cortical connectivity between anterior and posterior cortical regions would be increased during accelerated recovery induced by ketamine when compared to saline-treated controls. Rodents were instrumented with intracranial EEG electrodes and general anesthesia was induced with isoflurane anesthesia. After 37.5 min of continuous isoflurane anesthesia, a subanesthetic dose of ketamine (25 mg/kg intraperitoneal) was administered, with evidence of a 44% reduction in emergence time. In this study, we analyzed gamma and theta coherence (measure of undirected functional connectivity) and normalized symbolic transfer entropy (measure of directed functional connectivity) between frontal and parietal cortices during various levels of consciousness, with a focus on emergence from isoflurane anesthesia. During accelerated emergence in the ketamine-treated group, there was increased frontal-parietal coherence { p = 0.005, 0.05-0.23 [95% confidence interval (CI)]} and normalized symbolic transfer entropy [frontal to parietal: p < 0.001, 0.010-0.026 (95% CI); parietal to frontal: p < 0.001, 0.009-0.025 (95% CI)] in high-frequency gamma bandwidth as compared with the saline-treated group. Surrogates of cortical information exchange in high-frequency gamma are increased in association with accelerated recovery from anesthesia. This finding adds evidence suggesting a functional significance of high-gamma information transfer in consciousness.

Statistical Measurement of the Gamma-Ray Source-count Distribution as a Function of Energy

NASA Astrophysics Data System (ADS)

Zechlin, Hannes-S.; Cuoco, Alessandro; Donato, Fiorenza; Fornengo, Nicolao; Regis, Marco

2016-08-01

Statistical properties of photon count maps have recently been proven as a new tool to study the composition of the gamma-ray sky with high precision. We employ the 1-point probability distribution function of six years of Fermi-LAT data to measure the source-count distribution dN/dS and the diffuse components of the high-latitude gamma-ray sky as a function of energy. To that aim, we analyze the gamma-ray emission in five adjacent energy bands between 1 and 171 GeV. It is demonstrated that the source-count distribution as a function of flux is compatible with a broken power law up to energies of ˜50 GeV. The index below the break is between 1.95 and 2.0. For higher energies, a simple power-law fits the data, with an index of {2.2}-0.3+0.7 in the energy band between 50 and 171 GeV. Upper limits on further possible breaks as well as the angular power of unresolved sources are derived. We find that point-source populations probed by this method can explain {83}-13+7% ({81}-19+52%) of the extragalactic gamma-ray background between 1.04 and 1.99 GeV (50 and 171 GeV). The method has excellent capabilities for constraining the gamma-ray luminosity function and the spectra of unresolved blazars.

Master curves and radial distribution functions for shear dilatancy of liquid n-hexadecane via nonequilibrium molecular dynamics simulations.

PubMed

Tseng, Huan-Chang; Wu, Jiann-Shing; Chang, Rong-Yeu

2009-04-28

Shear dilatancy, a significant nonlinear behavior of nonequilibrium thermodynamics states, has been observed in nonequilibrium molecular dynamics (NEMD) simulations for liquid n-hexadecane fluid under extreme shear conditions. The existence of shear dilatancy is relevant to the relationship between the imposed shear rate gamma and the critical shear rate gamma(c). Consequently, as gammagamma(c), the intermolecular distance is lengthened substantially by strong shear deformation breaking the equilibrium thermodynamic state so that shear dilatancy takes place. Notably, a characteristic shear rate gamma(m), which depends on the root mean square molecular velocity and the average free molecular distance, is found in nonequilibrium thermodynamics state curves. Studies of the variations in the intermolecular radial distribution function (RDF) with respect to the shear rate provide a direct measure of the variation in the degree of intermolecular separation. Additionally, the variations of the RDF curve in the microscopic regime are consistent with those of the nonequilibrium thermodynamic state in the macroscopic world. By inspecting the overall shape of the RDF curve, it can be readily corroborated that the fluid of interest exists in the liquid state. More importantly, both primary characteristic values, the equilibrium thermodynamic state variable and a particular shear rate of gamma(p), are determined cautiously, with gamma(p) depending on the gamma(m) value and the square root of pressure. Thereby, the nonequilibrium thermodynamic state curves can be normalized as temperature-, pressure-, and density-invariant master curves, formulated by applying the Cross constitutive equation. Clearly, gamma(c) occurs at which a reduced shear rate gamma/gamma(p) approaches 0.1. Furthermore, the trends in the rates of shear dilatancy in both the constant-pressure and constant-volume NEMD systems under isothermal conditions conform to the cyclic rule of pressure, as a function of density and shear rate.

Applying the new gamma ray imager diagnostic to measurements of runaway electron Bremsstrahlung radiation in the DIII-D Tokamak (invited)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cooper, C. M., E-mail: coopercm@fusion.gat.com; Pace, D. C.; Paz-Soldan, C.

2016-11-15

A new gamma ray imager (GRI) is developed to probe the electron distribution function with 2D spatial resolution during runaway electron (RE) experiments at the DIII-D tokamak. The diagnostic is sensitive to 0.5–100 MeV gamma rays, allowing characterization of the RE distribution function evolution during RE growth and dissipation. The GRI consists of a lead “pinhole camera” mounted on the DIII-D midplane with 123 honeycombed tangential chords 20 cm wide that span the vessel interior. Up to 30 bismuth germanate (BGO) scintillation detectors capture RE bremsstrahlung radiation for Pulse Height Analysis (PHA) capable of discriminating up to 20 000 pulses permore » second. Digital signal processing routines combining shaping filters are performed during PHA to reject noise and record gamma ray energy. The GRI setup and PHA algorithms will be described and initial data from experiments will be presented. A synthetic diagnostic is developed to generate the gamma ray spectrum of a GRI channel given the plasma information and a prescribed distribution function. Magnetic reconstructions of the plasma are used to calculate the angle between every GRI sightline and orient and discriminate gamma rays emitted by a field-aligned RE distribution function.« less

Applying the new gamma ray imager diagnostic to measurements of runaway electron Bremsstrahlung radiation in the DIII-D Tokamak (invited)

NASA Astrophysics Data System (ADS)

Cooper, C. M.; Pace, D. C.; Paz-Soldan, C.; Commaux, N.; Eidietis, N. W.; Hollmann, E. M.; Shiraki, D.

2016-11-01

A new gamma ray imager (GRI) is developed to probe the electron distribution function with 2D spatial resolution during runaway electron (RE) experiments at the DIII-D tokamak. The diagnostic is sensitive to 0.5-100 MeV gamma rays, allowing characterization of the RE distribution function evolution during RE growth and dissipation. The GRI consists of a lead "pinhole camera" mounted on the DIII-D midplane with 123 honeycombed tangential chords 20 cm wide that span the vessel interior. Up to 30 bismuth germanate (BGO) scintillation detectors capture RE bremsstrahlung radiation for Pulse Height Analysis (PHA) capable of discriminating up to 20 000 pulses per second. Digital signal processing routines combining shaping filters are performed during PHA to reject noise and record gamma ray energy. The GRI setup and PHA algorithms will be described and initial data from experiments will be presented. A synthetic diagnostic is developed to generate the gamma ray spectrum of a GRI channel given the plasma information and a prescribed distribution function. Magnetic reconstructions of the plasma are used to calculate the angle between every GRI sightline and orient and discriminate gamma rays emitted by a field-aligned RE distribution function.

Applying the new gamma ray imager diagnostic to measurements of runaway electron Bremsstrahlung radiation in the DIII-D Tokamak (invited).

PubMed

Cooper, C M; Pace, D C; Paz-Soldan, C; Commaux, N; Eidietis, N W; Hollmann, E M; Shiraki, D

2016-11-01

A new gamma ray imager (GRI) is developed to probe the electron distribution function with 2D spatial resolution during runaway electron (RE) experiments at the DIII-D tokamak. The diagnostic is sensitive to 0.5-100 MeV gamma rays, allowing characterization of the RE distribution function evolution during RE growth and dissipation. The GRI consists of a lead "pinhole camera" mounted on the DIII-D midplane with 123 honeycombed tangential chords 20 cm wide that span the vessel interior. Up to 30 bismuth germanate (BGO) scintillation detectors capture RE bremsstrahlung radiation for Pulse Height Analysis (PHA) capable of discriminating up to 20 000 pulses per second. Digital signal processing routines combining shaping filters are performed during PHA to reject noise and record gamma ray energy. The GRI setup and PHA algorithms will be described and initial data from experiments will be presented. A synthetic diagnostic is developed to generate the gamma ray spectrum of a GRI channel given the plasma information and a prescribed distribution function. Magnetic reconstructions of the plasma are used to calculate the angle between every GRI sightline and orient and discriminate gamma rays emitted by a field-aligned RE distribution function.

Applying the new gamma ray imager diagnostic to measurements of runaway electron Bremsstrahlung radiation in the DIII-D Tokamak (invited)

DOE PAGES

Cooper, C. M.; Pace, D. C.; Paz-Soldan, C.; ...

2016-08-30

A new gamma ray imager (GRI) is developed to probe the electron distribution function with 2D spatial resolution during runaway electron (RE) experiments at the DIII-D tokamak. The diagnostic is sensitive to 0.5-100 MeV gamma rays, allowing characterization of the RE distribution function evolution during RE growth and dissipation. The GRI consists of a lead "pinhole camera" mounted on the DIII-D midplane with 123 honeycombed tangential chords 20 cm wide that span the vessel interior. Up to 30 bismuth germanate (BGO) scintillation detectors capture RE bremsstrahlung radiation for Pulse Height Analysis (PHA) capable of discriminating up to 20,000 pulses permore » second. Digital signal processing routines combining shaping filters are performed during PHA to reject noise and record gamma ray energy. The GRI setup and PHA algorithms will be described and initial data from experiments will be presented. A synthetic diagnostic is developed to generate the gamma ray spectrum of a GRI channel given the plasma information and a prescribed distribution function. Furthermore, magnetic reconstructions of the plasma are used to calculate the angle between every GRI sightline and orient and discriminate gamma rays emitted by a field-aligned RE distribution function.« less

Graft-versus-host disease causes failure of donor hematopoiesis and lymphopoiesis in interferon-gamma receptor-deficient hosts.

PubMed

Delisle, Jean-Sébastien; Gaboury, Louis; Bélanger, Marie-Pier; Tassé, Eliane; Yagita, Hideo; Perreault, Claude

2008-09-01

The immunopathologic condition known as graft-versus-host disease (GVHD) results from a type I T-cell process. However, a prototypical type I cytokine, interferon-gamma (IFN-gamma), can protect against several manifestations of GVHD in recipients of major histocompatibility complex (MHC)-mismatched hematopoietic cells. We transplanted hematopoietic cells from C3H.SW donors in wild-type (wt) and IFN-gamma-receptor-deficient (IFN-gammaRKO) MHC-matched C57BL/6 recipients. In IFN-gammaRKO recipients, host cells were unresponsive to IFN-gamma, whereas wt donor cells were exposed to exceptionally high levels of IFN-gamma. From an IFN-gamma perspective, we could therefore evaluate the impact of a loss-of-function on host cells and gain-of-function on donor cells. We found that lack of IFN-gammaR prevented up-regulation of MHC proteins on host cells but did not mitigate damage to most target organs. Two salient phenotypes in IFN-gammaRKO recipients involved donor cells: lymphoid hypoplasia and hematopoietic failure. Lymphopenia was due to FasL-induced apoptosis and decreased cell proliferation. Bone marrow aplasia resulted from a decreased proliferation of hematopoietic stem/progenitor cells that was associated with down-regulation of 2 genes negatively regulated by IFN-gamma: Ccnd1 and Myc. We conclude that IFN-gamma produced by alloreactive T cells may entail a severe graft-versus-graft reaction and could be responsible for cytopenias that are frequently observed in subjects with GVHD.

Unconscious Learning versus Visual Perception: Dissociable Roles for Gamma Oscillations Revealed in MEG

ERIC Educational Resources Information Center

Chaumon, Maximilien; Schwartz, Denis; Tallon-Baudry, Catherine

2009-01-01

Oscillatory synchrony in the gamma band (30-120 Hz) has been involved in various cognitive functions including conscious perception and learning. Explicit memory encoding, in particular, relies on enhanced gamma oscillations. Does this finding extend to unconscious memory encoding? Can we dissociate gamma oscillations related to unconscious…

Galactic plane gamma-radiation

NASA Technical Reports Server (NTRS)

Hartman, R. C.; Kniffen, D. A.; Thompson, D. J.; Fichtel, C. E.; Ogelman, H. B.; Tumer, T.; Ozel, M. E.

1979-01-01

Analysis of the SAS 2 data together with the COS B results shows that the distribution of galactic gamma-radiation has several similarities to that of other large-scale tracers of galactic structure. The radiation is primarily confined to a thin disc which exhibits offsets from b = 0 degrees similar to warping at radio frequencies. The principal distinction of the gamma-radiation is a stronger contrast in intensity between the region from 310 to 45 degrees in longitude and the regions away from the center that can be attributed to a variation in cosmic-ray density as a function of position in Galaxy. The diffuse galactic gamma-ray energy spectrum shows no significant variation in direction, and the spectrum seen along the plane is the same as that for the galactic component of the gamma-radiation at high altitudes. The uniformity of the galactic gamma-ray spectrum, the smooth decrease in intensity as a function of altitude, and the absence of any galactic gamma-ray sources at high altitudes indicate a diffuse origin for bulk of the galactic gamma-radiation rather than a collection of localized sources.

Human EEG gamma oscillations in neuropsychiatric disorders.

PubMed

Herrmann, C S; Demiralp, T

2005-12-01

Due to their small amplitude, the importance of high-frequency EEG oscillations with respect to cognitive functions and disorders is often underestimated as compared to slower oscillations. This article reviews the literature on the alterations of gamma oscillations (about 30-80 Hz) during the course of neuropsychiatric disorders and relates them to a model for the functional role of these oscillations for memory matching. The synchronous firing of neurons in the gamma-band has been proposed to bind multiple features of an object, which are coded in a distributed manner in the brain, and is modulated by cognitive processes such as attention and memory. In certain neuropsychiatric disorders the gamma activity shows significant changes. In schizophrenic patients, negative symptoms correlate with a decrease of gamma responses, whereas a significant increase in gamma amplitudes is observed during positive symptoms such as hallucinations. A reduction is also observed in Alzheimer's Disease (AD), whereas an increase is found in epileptic patients, probably reflecting both cortical excitation and perceptual distortions such as déjà vu phenomena frequently observed in epilepsy. ADHD patients also exhibit increased gamma amplitudes. A hypothesis of a gamma axis of these disorders mainly based on the significance of gamma oscillations for memory matching is formulated.

Characterization of phospholipase C gamma enzymes with gain-of-function mutations.

PubMed

Everett, Katy L; Bunney, Tom D; Yoon, Youngdae; Rodrigues-Lima, Fernando; Harris, Richard; Driscoll, Paul C; Abe, Koichiro; Fuchs, Helmut; de Angelis, Martin Hrabé; Yu, Philipp; Cho, Wohnwa; Katan, Matilda

2009-08-21

Phospholipase C gamma isozymes (PLC gamma 1 and PLC gamma 2) have a crucial role in the regulation of a variety of cellular functions. Both enzymes have also been implicated in signaling events underlying aberrant cellular responses. Using N-ethyl-N-nitrosourea (ENU) mutagenesis, we have recently identified single point mutations in murine PLC gamma 2 that lead to spontaneous inflammation and autoimmunity. Here we describe further, mechanistic characterization of two gain-of-function mutations, D993G and Y495C, designated as ALI5 and ALI14. The residue Asp-993, mutated in ALI5, is a conserved residue in the catalytic domain of PLC enzymes. Analysis of PLC gamma 1 and PLC gamma 2 with point mutations of this residue showed that removal of the negative charge enhanced PLC activity in response to EGF stimulation or activation by Rac. Measurements of PLC activity in vitro and analysis of membrane binding have suggested that ALI5-type mutations facilitate membrane interactions without compromising substrate binding and hydrolysis. The residue mutated in ALI14 (Tyr-495) is within the spPH domain. Replacement of this residue had no effect on folding of the domain and enhanced Rac activation of PLC gamma 2 without increasing Rac binding. Importantly, the activation of the ALI14-PLC gamma 2 and corresponding PLC gamma 1 variants was enhanced in response to EGF stimulation and bypassed the requirement for phosphorylation of critical tyrosine residues. ALI5- and ALI14-type mutations affected basal activity only slightly; however, their combination resulted in a constitutively active PLC. Based on these data, we suggest that each mutation could compromise auto-inhibition in the inactive PLC, facilitating the activation process; in addition, ALI5-type mutations could enhance membrane interaction in the activated state.

Specific or nonspecific? Evaluation of band, baseline, and cognitive specificity of sensorimotor rhythm- and gamma-based neurofeedback.

PubMed

Kober, Silvia Erika; Witte, Matthias; Neuper, Christa; Wood, Guilherme

2017-10-01

Neurofeedback (NF) is often criticized because of the lack of empirical evidence of its specificity. Our present study thus focused on the specificity of NF on three levels: band specificity, cognitive specificity, and baseline specificity. Ten healthy middle-aged individuals performed ten sessions of SMR (sensorimotor rhythm, 12-15Hz) NF training. A second group (N=10) received feedback of a narrow gamma band (40-43Hz). Effects of NF on EEG resting measurements (tonic EEG) and cognitive functions (memory, intelligence) were evaluated using a pre-post design. Both training groups were able to linearly increase the target training frequencies (either SMR or gamma), indicating the trainability of these EEG frequencies. Both NF training protocols led to nonspecific changes in other frequency bands during NF training. While SMR NF only led to concomitant changes in slower frequencies, gamma training affected nearly the whole power spectrum. SMR NF specifically improved memory functions. Gamma training showed only marginal effects on cognitive functions. SMR power assessed during resting measurements significantly increased after SMR NF training compared to a pre-assessment, indicating specific effects of SMR NF on baseline/tonic EEG. The gamma group did not show any pre-post changes in their EEG resting activity. In conclusion, SMR NF specifically affects cognitive functions (cognitive specificity) and tonic EEG (baseline specificity), while increasing SMR during NF training nonspecifically affects slower EEG frequencies as well (band non-specificity). Gamma NF was associated with nonspecific effects on the EEG power spectrum during training, which did not lead to considerable changes in cognitive functions or baseline EEG activity. Copyright © 2017 Elsevier B.V. All rights reserved.

Statistical measurement of the gamma-ray source-count distribution as a function of energy

DOE PAGES

Zechlin, Hannes-S.; Cuoco, Alessandro; Donato, Fiorenza; ...

2016-07-29

Statistical properties of photon count maps have recently been proven as a new tool to study the composition of the gamma-ray sky with high precision. Here, we employ the 1-point probability distribution function of six years of Fermi-LAT data to measure the source-count distribution dN/dS and the diffuse components of the high-latitude gamma-ray sky as a function of energy. To that aim, we analyze the gamma-ray emission in five adjacent energy bands between 1 and 171 GeV. It is demonstrated that the source-count distribution as a function of flux is compatible with a broken power law up to energies of ~50 GeV. Furthermore, the index below the break is between 1.95 and 2.0. For higher energies, a simple power-law fits the data, with an index ofmore » $${2.2}_{-0.3}^{+0.7}$$ in the energy band between 50 and 171 GeV. Upper limits on further possible breaks as well as the angular power of unresolved sources are derived. We find that point-source populations probed by this method can explain $${83}_{-13}^{+7}$$% ($${81}_{-19}^{+52}$$%) of the extragalactic gamma-ray background between 1.04 and 1.99 GeV (50 and 171 GeV). Our method has excellent capabilities for constraining the gamma-ray luminosity function and the spectra of unresolved blazars.« less

Statistical measurement of the gamma-ray source-count distribution as a function of energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zechlin, Hannes-S.; Cuoco, Alessandro; Donato, Fiorenza

Statistical properties of photon count maps have recently been proven as a new tool to study the composition of the gamma-ray sky with high precision. Here, we employ the 1-point probability distribution function of six years of Fermi-LAT data to measure the source-count distribution dN/dS and the diffuse components of the high-latitude gamma-ray sky as a function of energy. To that aim, we analyze the gamma-ray emission in five adjacent energy bands between 1 and 171 GeV. It is demonstrated that the source-count distribution as a function of flux is compatible with a broken power law up to energies of ~50 GeV. Furthermore, the index below the break is between 1.95 and 2.0. For higher energies, a simple power-law fits the data, with an index ofmore » $${2.2}_{-0.3}^{+0.7}$$ in the energy band between 50 and 171 GeV. Upper limits on further possible breaks as well as the angular power of unresolved sources are derived. We find that point-source populations probed by this method can explain $${83}_{-13}^{+7}$$% ($${81}_{-19}^{+52}$$%) of the extragalactic gamma-ray background between 1.04 and 1.99 GeV (50 and 171 GeV). Our method has excellent capabilities for constraining the gamma-ray luminosity function and the spectra of unresolved blazars.« less

GADRAS Detector Response Function.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mitchell, Dean J.; Harding, Lee; Thoreson, Gregory G

2014-11-01

The Gamma Detector Response and Analysis Software (GADRAS) applies a Detector Response Function (DRF) to compute the output of gamma-ray and neutron detectors when they are exposed to radiation sources. The DRF is fundamental to the ability to perform forward calculations (i.e., computation of the response of a detector to a known source), as well as the ability to analyze spectra to deduce the types and quantities of radioactive material to which the detectors are exposed. This document describes how gamma-ray spectra are computed and the significance of response function parameters that define characteristics of particular detectors.

Interferon-gamma: biologic functions and HCV therapy (type I/II) (1 of 2 parts).

PubMed

Gattoni, A; Parlato, A; Vangieri, B; Bresciani, M; Derna, R

2006-01-01

This review is aimed at exhaustively presenting and discussing the interferon-gamma (IFN-gamma), a cytokine that plays an important role in inducing and modulating an array of immune responses. A review of the most significant and recent clinical trials was performed. Although IFN-gamma has some antiviral activity, it is much less active in this regard than type I IFNs. IFN-gamma is involved in the regulation of nearly all phases of the immune and inflammatory responses, including the activation and differentiation of T cells, B cells, NK cells, macrophages, and others. It is therefore best regarded as a distint immunoregulatory cytokine. IFN-gamma secretion is a hallmark of Th1 lymphocytes. It is also secreted by nearly all CD8 T cells, by some Th0 cells, and by NK cells. Each of these cell types secretes IFN-gamma only when activated, usually as part of immune response and especially in response to IL-2 and IL-12. IFN-gamma production is inhibited by IL-4, IL-10, TGFbeta, glucocorticoids, cyclosporin A and FK506. Nearly all cell types express the heterodimeric receptor for IFN-beta and respond to this cytokine by increasing the surface expression of class I MHC proteins. As a result, virtually any cell in the vicinity of an IFN-beta-secreting cell becomes more efficient at presenting endogenous antigens and hence a better target for cytotoxic killing if it harbors an intracellular pathogen. Unlike the type I IFNs, IFN-gamma also increases the expression of class II MHC proteins on professional APCs, and so promotes antigen presentation to helper T cells as well. It also induces de novo expression of class II MHC proteins on venular endothelial cells and on some other epithelial and connective tissue cells that do not otherwise express them, thus enabling these cell types to function as temporary APCs at sites of intense immune reactions. The effector functions of NK cells are to lyse virus-infected cells and to secrete IFN-gamma, which activates macrofages to destroy phagocytosed microbes. The mechanism of NK cell-mediates cytolysis is essentially the same as that of cytolysis by CTLS. NK cells lyse virally infected cells before antigen specific CTLS came become fully active, that is, during the first few days after viral infection. NK cells are expanded and activated by cytokines of innate immunity, such as IL-12 and IL-15, and they kill infected cells, especially those that display reduced levels of class I molecoles. Some tumors, especially those of hematopoietic origin, are targets of NK cells, perlevels or types of class I MHC molecules. Therefore, IFN-gamma serves critical functions in innate immunity and in specific cell-mediated immunity (in addition, IFN activates neutrophilis and stimulates the cytolitic activity of NK cells). Many IFNs-gamma induced effects result in heigtened immune surveillance. IFN-gamma is a remarkable cytokine that orchestrates many distinct cellular programs through transcriptional control over large numbers of genes. Many IFNs-gamma-induced effects resulting in heightend immune surveillance and immune system function during infection have been discussed in this review. As the pathogens (microorganism with the potential to cause tissue injury or disease) augment local IFN-gamma production, and IFN-gamma augments the immune system response, an important function of IFN-gamma during in vivo infection is suggested. IFN-gamma is primarily secreted by activated T cells and natural killer cells, and can promote macrophage activation, mediate antiviral e antibacterial immunity, enhance antigen presentation, orchestrate activation of the innate immune system, coordinate lymphocyte-endothelium interaction, regulate Th1/Th2 balance, and control cellular proliferation and apoptosis.

Astrophysical gamma-ray production by inverse Compton interactions of relativistic electrons

NASA Technical Reports Server (NTRS)

Schlickeiser, R.

1979-01-01

The inverse Compton scattering of background photon gases by relativistic electrons is a good candidate for the production of high-energy gamma rays in the diffuse interstellar medium as well as in discrete sources. By discussing the special case of the scattering of the diffuse starlight in the interstellar medium by cosmic ray electrons, we demonstrate that previous derivations of the gamma ray source function for this process on the basis of the Thomson limit of the Klein-Nishina cross section lead to incorrect values for gamma-ray energies above 100 MeV. It is shown that the Thomson limit is not applicable for the calculation of gamma-ray source functions in astrophysical circumstances in which target photons with energies greater than 1 eV are scattered by relativistic electrons.

Analysis of PGC-1{alpha} variants Gly482Ser and Thr612Met concerning their PPAR{gamma}2-coactivation function

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nitz, Inke; Ewert, Agnes; Klapper, Maja

2007-02-09

Peroxisome proliferator-activated receptor-{gamma} coactivator-1{alpha} (PGC-1{alpha}) is a cofactor involved in adaptive thermogenesis, fatty acid oxidation, and gluconeogenesis. Dysfunctions of this protein are likely to contribute to the development of obesity and the metabolic syndrome. This is in part but not definitely confirmed by results of population studies. The aim of this study was to investigate if common genetic variants rs8192678 (Gly482Ser) and rs3736265 (Thr612Met) in the PGC-1{alpha} gene lead to a functional consequence in cofactor activity using peroxisome proliferator-activated receptor-{gamma} 2 (PPAR{gamma}2) as interacting transcription factor. Reporter gene assays in HepG2 cells with wildtype and mutant proteins of both PGC1{alpha}more » and PPAR{gamma}2 (Pro12Ala, rs1801282) using the acyl-CoA-binding protein (ACBP) promoter showed no difference in coactivator activity. This is First study implicating that the Gly482Ser and Thr612Met polymorphisms in PGC-1{alpha} and Pro12Ala polymorphism in PPAR{gamma}2 do not affect the functional integrity of these proteins.« less

Vascular endothelial cells express isoforms of protein kinase A inhibitor.

PubMed

Lum, Hazel; Hao, Zengping; Gayle, Dave; Kumar, Priyadarsini; Patterson, Carolyn E; Uhler, Michael D

2002-01-01

The expression and function of the endogenous inhibitor of cAMP-dependent protein kinase (PKI) in endothelial cells are unknown. In this study, overexpression of rabbit muscle PKI gene into endothelial cells inhibited the cAMP-mediated increase and exacerbated thrombin-induced decrease in endothelial barrier function. We investigated PKI expression in human pulmonary artery (HPAECs), foreskin microvessel (HMECs), and brain microvessel endothelial cells (HBMECs). RT-PCR using specific primers for human PKI alpha, human PKI gamma, and mouse PKI beta sequences detected PKI alpha and PKI gamma mRNA in all three cell types. Sequencing and BLAST analysis indicated that forward and reverse DNA strands for PKI alpha and PKI gamma were of >96% identity with database sequences. RNase protection assays showed protection of the 542 nucleotides in HBMEC and HPAEC PKI alpha mRNA and 240 nucleotides in HBMEC, HPAEC, and HMEC PKI gamma mRNA. Western blot analysis indicated that PKI gamma protein was detected in all three cell types, whereas PKI alpha was found in HBMECs. In summary, endothelial cells from three different vascular beds express PKI alpha and PKI gamma, which may be physiologically important in endothelial barrier function.

Renormalization of loop functions for all loops

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brandt, R.A.; Neri, F.; Sato, M.

1981-08-15

It is shown that the vacuum expectation values W(C/sub 1/,xxx, C/sub n/) of products of the traces of the path-ordered phase factors P exp(igcontour-integral/sub C/iA/sub ..mu../(x)dx/sup ..mu../) are multiplicatively renormalizable in all orders of perturbation theory. Here A/sub ..mu../(x) are the vector gauge field matrices in the non-Abelian gauge theory with gauge group U(N) or SU(N), and C/sub i/ are loops (closed paths). When the loops are smooth (i.e., differentiable) and simple (i.e., non-self-intersecting), it has been shown that the generally divergent loop functions W become finite functions W when expressed in terms of the renormalized coupling constant and multipliedmore » by the factors e/sup -K/L(C/sub i/), where K is linearly divergent and L(C/sub i/) is the length of C/sub i/. It is proved here that the loop functions remain multiplicatively renormalizable even if the curves have any finite number of cusps (points of nondifferentiability) or cross points (points of self-intersection). If C/sub ..gamma../ is a loop which is smooth and simple except for a single cusp of angle ..gamma.., then W/sub R/(C/sub ..gamma../) = Z(..gamma..)W(C/sub ..gamma../) is finite for a suitable renormalization factor Z(..gamma..) which depends on ..gamma.. but on no other characteristic of C/sub ..gamma../. This statement is made precise by introducing a regularization, or via a loop-integrand subtraction scheme specified by a normalization condition W/sub R/(C-bar/sub ..gamma../) = 1 for an arbitrary but fixed loop C-bar/sub ..gamma../. Next, if C/sub ..beta../ is a loop which is smooth and simple except for a cross point of angles ..beta.., then W(C/sub ..beta../) must be renormalized together with the loop functions of associated sets S/sup i//sub ..beta../ = )C/sup i//sub 1/,xxx, C/sup i//sub p/i) (i = 2,xxx,I) of loops C/sup i//sub q/ which coincide with certain parts of C/sub ..beta../equivalentC/sup 1//sub 1/. Then W/sub R/(S/sup i//sub ..beta../) = Z/sup i/j(..beta..)W(S/sup j//sub ..beta../) is finite for a suitable matrix Z/sup i/j(..beta..).« less

Accelerated Recovery of Consciousness after General Anesthesia Is Associated with Increased Functional Brain Connectivity in the High-Gamma Bandwidth

PubMed Central

Li, Duan; Hambrecht-Wiedbusch, Viviane S.; Mashour, George A.

2017-01-01

Recent data from our laboratory demonstrate that high-frequency gamma connectivity across the cortex is present during consciousness and depressed during unconsciousness. However, these data were derived from static and well-defined states of arousal rather than during transitions that would suggest functional relevance. We also recently found that subanesthetic ketamine administered during isoflurane anesthesia accelerates recovery upon discontinuation of the primary anesthetic and increases gamma power during emergence. In the current study we re-analyzed electroencephalogram (EEG) data to test the hypothesis that functional cortical connectivity between anterior and posterior cortical regions would be increased during accelerated recovery induced by ketamine when compared to saline-treated controls. Rodents were instrumented with intracranial EEG electrodes and general anesthesia was induced with isoflurane anesthesia. After 37.5 min of continuous isoflurane anesthesia, a subanesthetic dose of ketamine (25 mg/kg intraperitoneal) was administered, with evidence of a 44% reduction in emergence time. In this study, we analyzed gamma and theta coherence (measure of undirected functional connectivity) and normalized symbolic transfer entropy (measure of directed functional connectivity) between frontal and parietal cortices during various levels of consciousness, with a focus on emergence from isoflurane anesthesia. During accelerated emergence in the ketamine-treated group, there was increased frontal-parietal coherence {p = 0.005, 0.05–0.23 [95% confidence interval (CI)]} and normalized symbolic transfer entropy [frontal to parietal: p < 0.001, 0.010–0.026 (95% CI); parietal to frontal: p < 0.001, 0.009–0.025 (95% CI)] in high-frequency gamma bandwidth as compared with the saline-treated group. Surrogates of cortical information exchange in high-frequency gamma are increased in association with accelerated recovery from anesthesia. This finding adds evidence suggesting a functional significance of high-gamma information transfer in consciousness. PMID:28392760

[Targeted inactivation of gamma-synuclein gene affects anxiety and exploratory behaviour of mice].

PubMed

Kokhan, V S; Bolkunov, A V; Ustiugov, A A; Van'kin, G I; Shelkovnikova, T A; Redkozubova, O M; Strekalova, T V; Bukhman, V L; Ninkina, N N; Bachurin, S O

2011-01-01

Gamma(gamma)-synuclein is a member of synuclein family of cytoplasmic and predominantly neuronal proteins found only in vertebrates. Gamma-synuclein is abundant in axons and presynaptic terminals of neurons localized in brain regions involved in emotions, learning and memory. However, the role of gamma-synuclein in these brain functions was not previously assessed. We have demonstrated for the first time that the loss of gamma-synuclein results in a significant increase in the level of orientation response in novel environment and decrease in the level of state anxiety.

Ablation of phosphoinositide 3-kinase-gamma reduces the severity of acute pancreatitis.

PubMed

Lupia, Enrico; Goffi, Alberto; De Giuli, Paolo; Azzolino, Ornella; Bosco, Ornella; Patrucco, Enrico; Vivaldo, Maria Cristina; Ricca, Marco; Wymann, Matthias P; Hirsch, Emilio; Montrucchio, Giuseppe; Emanuelli, Giorgio

2004-12-01

In pancreatic acini, the G-protein-activated phosphoinositide 3-kinase-gamma (PI3K gamma) regulates several key pathological responses to cholecystokinin hyperstimulation in vitro. Thus, using mice lacking PI3K gamma, we studied the function of this enzyme in vivo in two different models of acute pancreatitis. The disease was induced by supramaximal concentrations of cerulein and by feeding mice a choline-deficient/ethionine-supplemented diet. Although the secretive function of isolated pancreatic acini was identical in mutant and control samples, in both models, genetic ablation of PI3K gamma significantly reduced the extent of acinar cell injury/necrosis. In agreement with a protective role of apoptosis in pancreatitis, PI3K gamma-deficient pancreata showed an increased number of apoptotic acinar cells, as determined by terminal dUTP nick-end labeling and caspase-3 activity. In addition, neutrophil infiltration within the pancreatic tissue was also reduced, suggesting a dual action of PI3K gamma, both in the triggering events within acinar cells and in the subsequent neutrophil recruitment and activation. Finally, the lethality of the choline-deficient/ethionine-supplemented diet-induced pancreatitis was significantly reduced in mice lacking PI3K gamma. Our results thus suggest that inhibition of PI3K gamma may be of therapeutic value in acute pancreatitis.

Shifts of Gamma Phase across Primary Visual Cortical Sites Reflect Dynamic Stimulus-Modulated Information Transfer.

PubMed

Besserve, Michel; Lowe, Scott C; Logothetis, Nikos K; Schölkopf, Bernhard; Panzeri, Stefano

2015-01-01

Distributed neural processing likely entails the capability of networks to reconfigure dynamically the directionality and strength of their functional connections. Yet, the neural mechanisms that may allow such dynamic routing of the information flow are not yet fully understood. We investigated the role of gamma band (50-80 Hz) oscillations in transient modulations of communication among neural populations by using measures of direction-specific causal information transfer. We found that the local phase of gamma-band rhythmic activity exerted a stimulus-modulated and spatially-asymmetric directed effect on the firing rate of spatially separated populations within the primary visual cortex. The relationships between gamma phases at different sites (phase shifts) could be described as a stimulus-modulated gamma-band wave propagating along the spatial directions with the largest information transfer. We observed transient stimulus-related changes in the spatial configuration of phases (compatible with changes in direction of gamma wave propagation) accompanied by a relative increase of the amount of information flowing along the instantaneous direction of the gamma wave. These effects were specific to the gamma-band and suggest that the time-varying relationships between gamma phases at different locations mark, and possibly causally mediate, the dynamic reconfiguration of functional connections.

Shifts of Gamma Phase across Primary Visual Cortical Sites Reflect Dynamic Stimulus-Modulated Information Transfer

PubMed Central

Besserve, Michel; Lowe, Scott C.; Logothetis, Nikos K.; Schölkopf, Bernhard; Panzeri, Stefano

2015-01-01

Distributed neural processing likely entails the capability of networks to reconfigure dynamically the directionality and strength of their functional connections. Yet, the neural mechanisms that may allow such dynamic routing of the information flow are not yet fully understood. We investigated the role of gamma band (50–80 Hz) oscillations in transient modulations of communication among neural populations by using measures of direction-specific causal information transfer. We found that the local phase of gamma-band rhythmic activity exerted a stimulus-modulated and spatially-asymmetric directed effect on the firing rate of spatially separated populations within the primary visual cortex. The relationships between gamma phases at different sites (phase shifts) could be described as a stimulus-modulated gamma-band wave propagating along the spatial directions with the largest information transfer. We observed transient stimulus-related changes in the spatial configuration of phases (compatible with changes in direction of gamma wave propagation) accompanied by a relative increase of the amount of information flowing along the instantaneous direction of the gamma wave. These effects were specific to the gamma-band and suggest that the time-varying relationships between gamma phases at different locations mark, and possibly causally mediate, the dynamic reconfiguration of functional connections. PMID:26394205

Fcgamma chain deficiency on hematopoietic cells ameliorates atherosclerosis in apoe-knockout mice by promoting Th2 responses

USDA-ARS?s Scientific Manuscript database

We have previously shown that oxLDL-immune complexes (oxLDL-IC) binding to Fcgamma receptors (Fc gamma R) expressed on human monocytes leads to induction of pro-inflammatory cytokines. Four classes of mouse Fc gamma Rs have been defined: Fc gamma RI, II, III, and IV. Functionally, Fc gamma Rs can be...

Structural and Biochemical Basis for the Binding Selectivity of Peroxisome Proliferator-activated Receptor [gamma] to PGC-1[alpha

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Yong; Kovach, Amanda; Suino-Powell, Kelly

2008-07-23

The functional interaction between the peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}) and its coactivator PGC-1{alpha} is crucial for the normal physiology of PPAR{gamma} and its pharmacological response to antidiabetic treatment with rosiglitazone. Here we report the crystal structure of the PPAR{gamma} ligand-binding domain bound to rosiglitazone and to a large PGC-1{alpha} fragment that contains two LXXLL-related motifs. The structure reveals critical contacts mediated through the first LXXLL motif of PGC-1{alpha} and the PPAR{gamma} coactivator binding site. Through a combination of biochemical and structural studies, we demonstrate that the first LXXLL motif is the most potent among all nuclear receptor coactivator motifsmore » tested, and only this motif of the two LXXLL-related motifs in PGC-1{alpha} is capable of binding to PPAR{gamma}. Our studies reveal that the strong interaction of PGC-1{alpha} and PPAR{gamma} is mediated through both hydrophobic and specific polar interactions. Mutations within the context of the full-length PGC-1{alpha} indicate that the first PGC-1{alpha} motif is necessary and sufficient for PGC-1{alpha} to coactivate PPAR{gamma} in the presence or absence of rosiglitazone. These results provide a molecular basis for specific recruitment and functional interplay between PPAR{gamma} and PGC-1{alpha} in glucose homeostasis and adipocyte differentiation.« less

Duration analysis using matching pursuit algorithm reveals longer bouts of gamma rhythm.

PubMed

Chandran Ks, Subhash; Seelamantula, Chandra Sekhar; Ray, Supratim

2018-03-01

The gamma rhythm (30-80 Hz), often associated with high-level cortical functions, is believed to provide a temporal reference frame for spiking activity, for which it should have a stable center frequency and linear phase for an extended duration. However, recent studies that have estimated the power and phase of gamma as a function of time suggest that gamma occurs in short bursts and lacks the temporal structure required to act as a reference frame. Here, we show that the bursty appearance of gamma arises from the variability in the spectral estimator used in these studies. To overcome this problem, we use another duration estimator based on a matching pursuit algorithm that robustly estimates the duration of gamma in simulated data. Applying this algorithm to gamma oscillations recorded from implanted microelectrodes in the primary visual cortex of awake monkeys, we show that the median gamma duration is greater than 300 ms, which is three times longer than previously reported values. NEW & NOTEWORTHY Gamma oscillations (30-80 Hz) have been hypothesized to provide a temporal reference frame for coordination of spiking activity, but recent studies have shown that gamma occurs in very short bursts. We show that existing techniques have severely underestimated the rhythm duration, use a technique based on the Matching Pursuit algorithm, which provides a robust estimate of the duration, and show that the median duration of gamma is greater than 300 ms, much longer than previous estimates.

Duration analysis using matching pursuit algorithm reveals longer bouts of gamma rhythm

PubMed Central

Chandran KS, Subhash; Seelamantula, Chandra Sekhar

2018-01-01

The gamma rhythm (30–80 Hz), often associated with high-level cortical functions, is believed to provide a temporal reference frame for spiking activity, for which it should have a stable center frequency and linear phase for an extended duration. However, recent studies that have estimated the power and phase of gamma as a function of time suggest that gamma occurs in short bursts and lacks the temporal structure required to act as a reference frame. Here, we show that the bursty appearance of gamma arises from the variability in the spectral estimator used in these studies. To overcome this problem, we use another duration estimator based on a matching pursuit algorithm that robustly estimates the duration of gamma in simulated data. Applying this algorithm to gamma oscillations recorded from implanted microelectrodes in the primary visual cortex of awake monkeys, we show that the median gamma duration is greater than 300 ms, which is three times longer than previously reported values. NEW & NOTEWORTHY Gamma oscillations (30–80 Hz) have been hypothesized to provide a temporal reference frame for coordination of spiking activity, but recent studies have shown that gamma occurs in very short bursts. We show that existing techniques have severely underestimated the rhythm duration, use a technique based on the Matching Pursuit algorithm, which provides a robust estimate of the duration, and show that the median duration of gamma is greater than 300 ms, much longer than previous estimates. PMID:29118193

Computer routines for probability distributions, random numbers, and related functions

USGS Publications Warehouse

Kirby, W.

1983-01-01

Use of previously coded and tested subroutines simplifies and speeds up program development and testing. This report presents routines that can be used to calculate various probability distributions and other functions of importance in statistical hydrology. The routines are designed as general-purpose Fortran subroutines and functions to be called from user-written main progress. The probability distributions provided include the beta, chi-square, gamma, Gaussian (normal), Pearson Type III (tables and approximation), and Weibull. Also provided are the distributions of the Grubbs-Beck outlier test, Kolmogorov 's and Smirnov 's D, Student 's t, noncentral t (approximate), and Snedecor F. Other mathematical functions include the Bessel function, I sub o, gamma and log-gamma functions, error functions, and exponential integral. Auxiliary services include sorting and printer-plotting. Random number generators for uniform and normal numbers are provided and may be used with some of the above routines to generate numbers from other distributions. (USGS)

Computer routines for probability distributions, random numbers, and related functions

USGS Publications Warehouse

Kirby, W.H.

1980-01-01

Use of previously codes and tested subroutines simplifies and speeds up program development and testing. This report presents routines that can be used to calculate various probability distributions and other functions of importance in statistical hydrology. The routines are designed as general-purpose Fortran subroutines and functions to be called from user-written main programs. The probability distributions provided include the beta, chisquare, gamma, Gaussian (normal), Pearson Type III (tables and approximation), and Weibull. Also provided are the distributions of the Grubbs-Beck outlier test, Kolmogorov 's and Smirnov 's D, Student 's t, noncentral t (approximate), and Snedecor F tests. Other mathematical functions include the Bessel function I (subzero), gamma and log-gamma functions, error functions and exponential integral. Auxiliary services include sorting and printer plotting. Random number generators for uniform and normal numbers are provided and may be used with some of the above routines to generate numbers from other distributions. (USGS)

Properties of {sup 112}Cd from the (n,n'{gamma}) reaction: Levels and level densities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garrett, P. E.; Lehmann, H.; Jolie, J.

2001-08-01

Levels in {sup 112}Cd have been studied through the (n,n'{gamma}) reaction with monoenergetic neutrons. An extended set of experiments that included excitation functions, {gamma}-ray angular distributions, and {gamma}{gamma} coincidence measurements was performed. A total of 375 {gamma} rays were placed in a level scheme comprising 200 levels (of which 238 {gamma}-ray assignments and 58 levels are newly established) up to 4 MeV in excitation. No evidence to support the existence of 47 levels as suggested in previous studies was found, and these have been removed from the level scheme. From the results, a comparison of the level density is mademore » with the constant temperature and back-shifted Fermi gas models. The back-shifted Fermi gas model with the Gilbert-Cameron spin cutoff parameter provided the best overall fit. Without using the neutron resonance information and only fitting the cumulative number of low-lying levels, the level density parameters extracted are a sensitive function of the maximum energy used in the fit.« less

Cross-frequency synchronization connects networks of fast and slow oscillations during visual working memory maintenance.

PubMed

Siebenhühner, Felix; Wang, Sheng H; Palva, J Matias; Palva, Satu

2016-09-26

Neuronal activity in sensory and fronto-parietal (FP) areas underlies the representation and attentional control, respectively, of sensory information maintained in visual working memory (VWM). Within these regions, beta/gamma phase-synchronization supports the integration of sensory functions, while synchronization in theta/alpha bands supports the regulation of attentional functions. A key challenge is to understand which mechanisms integrate neuronal processing across these distinct frequencies and thereby the sensory and attentional functions. We investigated whether such integration could be achieved by cross-frequency phase synchrony (CFS). Using concurrent magneto- and electroencephalography, we found that CFS was load-dependently enhanced between theta and alpha-gamma and between alpha and beta-gamma oscillations during VWM maintenance among visual, FP, and dorsal attention (DA) systems. CFS also connected the hubs of within-frequency-synchronized networks and its strength predicted individual VWM capacity. We propose that CFS integrates processing among synchronized neuronal networks from theta to gamma frequencies to link sensory and attentional functions.

Pathophysiologic roles of the fibrinogen gamma chain.

PubMed

Farrell, David H

2004-05-01

Fibrinogen binds through its gamma chains to cell surface receptors, growth factors, and coagulation factors to perform its key roles in fibrin clot formation, platelet aggregation, and wound healing. However, these binding interactions can also contribute to pathophysiologic processes, including inflammation and thrombosis. This review summarizes the latest findings on the role of the fibrinogen gamma chain in these processes, and illustrates the potential for therapeutic intervention. Novel gamma chain epitopes that bind platelet integrin alpha IIbbeta3 and leukocyte integrin alphaMbeta2 have been characterized, leading to the revision of former dogma regarding the processes of platelet aggregation, clot retraction, inflammation, and thrombosis. A series of studies has shown that the gamma chain serves as a depot for fibroblast growth factor-2 (FGF-2), which is likely to play an important role in wound healing. Inhibition of gamma chain function with the monoclonal antibody 7E9 has been shown to interfere with multiple fibrinogen activities, including factor XIIIa crosslinking, platelet adhesion, and platelet-mediated clot retraction. The role of the enigmatic variant fibrinogen gamma chain has also become clearer. Studies have shown that gamma chain binding to thrombin and factor XIII results in clots that are mechanically stiffer and resistant to fibrinolysis, which may explain the association between gammaA/gamma' fibrinogen levels and cardiovascular disease. The identification of new interactions with gamma chains has revealed novel targets for the treatment of inflammation and thrombosis. In addition, several exciting studies have shown new functions for the variant gamma chain that may contribute to cardiovascular disease.

Whole-exome sequencing reveals a rare interferon gamma receptor 1 mutation associated with myasthenia gravis.

PubMed

Qi, Guoyan; Liu, Peng; Gu, Shanshan; Yang, Hongxia; Dong, Huimin; Xue, Yinping

2018-04-01

Our study is aimed to explore the underlying genetic basis of myasthenia gravis. We collected a Chinese pedigree with myasthenia gravis, and whole-exome sequencing was performed on the two affected siblings and their parents. The candidate pathogenic gene was identified by bioinformatics filtering, which was further verified by Sanger sequencing. The homozygous mutation c.G40A (p.V14M) in interferon gamma receptor 1was identified. Moreover, the mutation was also detected in 3 cases of 44 sporadic myasthenia gravis patients. The p.V14M substitution in interferon gamma receptor 1 may affect the signal peptide function and the translocation on cell membrane, which could disrupt the binding of the ligand of interferon gamma and antibody production, contributing to myasthenia gravis susceptibility. We discovered that a rare variant c.G40A in interferon gamma receptor 1 potentially contributes to the myasthenia gravis pathogenesis. Further functional studies are needed to confirm the effect of the interferon gamma receptor 1 on the myasthenia gravis phenotype.

Galactic X-ray emission from pulsars

NASA Technical Reports Server (NTRS)

Harding, A. K.

1981-01-01

The contribution of pulsars to the gamma-ray flux from the galactic plane is examined using data from the most recent pulsar surveys. It is assumed that pulsar gamma-rays are produced by curvature radiation from relativistic particles above the polar cap and attenuated by pair production in the strong magnetic and electric fields. Assuming that all pulsars produce gamma-rays in this way, their luminosities can be predicted as a function of period and magnetic field strength. Using the distribution of pulsars in the galaxy as determined from data on 328 pulsars detected in three surveys, the local gamma-ray production spectrum, the longitude profile, and the latitude profile of pulsar gamma-ray flux are calculated. The largest sources of uncertainty in the size of the pulsar contribution are the value of the mean interstellar electron density, the turnover in the pulsar radio luminosity function, and the average pulsar magnetic field strength. A present estimate is that pulsars contribute from 15 to 20 % of the total flux of gamma-rays from the galactic plane.

Regulation of eIF2alpha phosphorylation by different functions that act during discrete phases in the herpes simplex virus type 1 life cycle.

PubMed

Mulvey, Matthew; Poppers, Jeremy; Sternberg, David; Mohr, Ian

2003-10-01

Multiple herpes simplex virus type 1 functions control translation by regulating phosphorylation of the initiation factor eIF2 on its alpha subunit. Both of the two known regulators, the gamma(1)34.5 and Us11 gene products, are produced late in the viral life cycle, although the gamma(1)34.5 gene is expressed prior to the gamma(2) Us11 gene, as gamma(2) genes require viral DNA replication for their expression while gamma(1) genes do not. The gamma(1)34.5 protein, through a GADD34-related domain, binds a cellular phosphatase (PP1alpha), maintaining pools of active, unphosphorylated eIF2. Infection of a variety of cultured cells with a gamma(1)34.5 mutant virus results in the accumulation of phosphorylated eIF2alpha and the inhibition of translation prior to the completion of the viral lytic program. Ectopic, immediate-early Us11 expression prevents eIF2alpha phosphorylation and the inhibition of translation observed in cells infected with a gamma(1)34.5 mutant by inhibiting activation of the cellular kinase PKR and the subsequent phosphorylation of eIF2alpha; however, a requirement for the Us11 protein, produced in its natural context as a gamma(2) polypeptide, remains to be demonstrated. To determine if Us11 regulates late translation, we generated two Us11 null viruses. In cells infected with a Us11 mutant, elevated levels of activated PKR and phosphorylated eIF2alpha were detected, viral translation rates were reduced 6- to 7-fold, and viral replication was reduced 13-fold compared to replication in cells infected with either wild-type virus or a virus in which the Us11 mutation was repaired. This establishes that the Us11 protein is critical for proper late translation rates. Moreover, it demonstrates that the shutoff of protein synthesis observed in cells infected with a gamma(1)34.5 mutant virus, previously ascribed solely to the gamma(1)34.5 mutation, actually results from the combined loss of gamma(1)34.5 and Us11 functions, as the gamma(2) Us11 mRNA is not translated in cells infected with a gamma(1)34.5 mutant.

Morning nutrition and executive function processes in preadolescents: modulation of frontal event-related theta, beta and gamma EEG oscillations during a go/ no-go task

USDA-ARS?s Scientific Manuscript database

Executive functions (i.e., goal-directed behavior such as inhibition and flexibility of action) have been linked to frontal brain regions and to covariations in oscillatory brain activity, e.g., theta and gamma activity. We studied the effects of morning nutritional status on executive function rel...

Regulation of PPAR{gamma} function by TNF-{alpha}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ye Jianping

2008-09-26

The nuclear receptor PPAR{gamma} is a lipid sensor that regulates lipid metabolism through gene transcription. Inhibition of PPAR{gamma} activity by TNF-{alpha} is involved in pathogenesis of insulin resistance, atherosclerosis, inflammation, and cancer cachexia. PPAR{gamma} activity is regulated by TNF-{alpha} at pre-translational and post-translational levels. Activation of serine kinases including IKK, ERK, JNK, and p38 may be involved in the TNF-regulation of PPAR{gamma}. Of the four kinases, IKK is a dominant signaling molecule in the TNF-regulation of PPAR{gamma}. IKK acts through at least two mechanisms: inhibition of PPAR{gamma} expression and activation of PPAR{gamma} corepressor. In this review article, literature is reviewedmore » with a focus on the mechanisms of PPAR{gamma} inhibition by TNF-{alpha}.« less

Composite space charge density functions for the calculation of gamma sensitivity of self-powered neutron detectors, using Warren's model

NASA Astrophysics Data System (ADS)

Mahant, A. K.; Rao, P. S.; Misra, S. C.

1994-07-01

In the calculational model developed by Warren and Shah for the computation of the gamma sensitivity ( Sγ) it has been observed that the computed Sγ value is quite sensitive to the space charge distribution function assumed for the insulator region and the energy of the gamma photons. The Sγ of SPNDs with Pt, Co and V emitters (manufactured by Thermocoax, France) has been measured at 60Co photon energy and a good correlation between the measured and computed values has been obtained using a composite space charge density function (CSCD), the details of which are presented in this paper. The arguments are extended for evaluating the Sγ values of several SPNDs for which Warren and Shah reported the measured values for a prompt fission gamma spectrum obtained in a swimming pool reactor. These results are also discussed.

Cognitive dysfunction in schizophrenia: convergence of gamma-aminobutyric acid and glutamate alterations.

PubMed

Lewis, David A; Moghaddam, Bita

2006-10-01

Impairments in certain cognitive functions mediated by the dorsolateral prefrontal cortex, such as working memory, are core features of schizophrenia. Convergent findings suggest that these disturbances are associated with alterations in markers of inhibitory gamma-aminobutyric acid and excitatory glutamate neurotransmission in the dorsolateral prefrontal cortex. Specifically, reduced gamma-aminobutyric acid synthesis is present in the subpopulation of gamma-aminobutyric acid neurons that express the calcium-binding protein parvalbumin. Despite presynaptic and postsynaptic compensatory responses, the resulting impaired inhibitory regulation of pyramidal neurons contributes to a reduction in the synchronized neuronal activity that is required for working memory function. Several lines of evidence suggest that these changes may be either secondary to or exacerbated by impaired signaling via the N-methyl-d-aspartate class of glutamate receptors. These findings suggest specific targets for therapeutic interventions to improve cognitive function in individuals with schizophrenia.

Gamma knife radiosurgery in movement disorders: Indications and limitations.

PubMed

Higuchi, Yoshinori; Matsuda, Shinji; Serizawa, Toru

2017-01-01

Functional radiosurgery has advanced steadily during the past half century since the development of the gamma knife technique for treating intractable cancer pain. Applications of radiosurgery for intracranial diseases have increased with a focus on understanding radiobiology. Currently, the use of gamma knife radiosurgery to ablate deep brain structures is not widespread because visualization of the functional targets remains difficult despite the increased availability of advanced neuroimaging technology. Moreover, most existing reports have a small sample size or are retrospective. However, increased experience with intraoperative neurophysiological evaluations in radiofrequency thalamotomy and deep brain stimulation supports anatomical and neurophysiological approaches to the ventralis intermedius nucleus. Two recent prospective studies have promoted the clinical application of functional radiosurgery for movement disorders. For example, unilateral gamma knife thalamotomy is a potential alternative to radiofrequency thalamotomy and deep brain stimulation techniques for intractable tremor patients with contraindications for surgery. Despite the promising efficacy of gamma knife thalamotomy, however, these studies did not include sufficient follow-up to confirm long-term effects. Herein, we review the radiobiology literature, various techniques, and the treatment efficacy of gamma knife radiosurgery for patients with movement disorders. Future research should focus on randomized controlled studies and long-term effects. © 2016 International Parkinson and Movement Disorder Society. © 2016 International Parkinson and Movement Disorder Society.

The structure and function of Alzheimer's gamma secretase enzyme complex.

PubMed

Krishnaswamy, Sudarsan; Verdile, Giuseppe; Groth, David; Kanyenda, Limbikani; Martins, Ralph N

2009-01-01

The production and accumulation of the beta amyloid protein (Abeta) is a key event in the cascade of oxidative and inflammatory processes that characterizes Alzheimer's disease (AD). A multi-subunit enzyme complex, referred to as gamma (gamma) secretase, plays a pivotal role in the generation of Abeta from its parent molecule, the amyloid precursor protein (APP). Four core components (presenilin, nicastrin, aph-1, and pen-2) interact in a high-molecular-weight complex to perform intramembrane proteolysis on a number of membrane-bound proteins, including APP and Notch. Inhibitors and modulators of this enzyme have been assessed for their therapeutic benefit in AD. However, although these agents reduce Abeta levels, the majority have been shown to have severe side effects in pre-clinical animal studies, most likely due to the enzymes role in processing other proteins involved in normal cellular function. Current research is directed at understanding this enzyme and, in particular, at elucidating the roles that each of the core proteins plays in its function. In addition, a number of interacting proteins that are not components of gamma-secretase also appear to play important roles in modulating enzyme activity. This review will discuss the structural and functional complexity of the gamma-secretase enzyme and the effects of inhibiting its activity.

Immune-enhancing activities of low molecular weight β-glucan depolymerized by gamma irradiation

NASA Astrophysics Data System (ADS)

Sung, Nak-Yun; Byun, Eui-Hong; Kwon, Sun-Kyu; Song, Beom-Seok; Choi, Jong-il; Kim, Jae-Hun; Byun, Myung-Woo; Yoo, Young-Choon; Kim, Mee-Ree; Lee, Ju-Woon

2009-07-01

β-glucans are structural cell wall polymers of many microorganisms and cereals which possess immunomodulatory properties and have been used in the food, cosmetic and medical industry. In our previous study, β-glucan was depolymerized by gamma irradiation and leads to improve the solubility and viscosity. This study was carried out to evaluate the functional properties, mainly immune-enhancing activities of low molecular weight β-glucan fragmented by gamma irradiation. The results showed that RAW 264.7 macrophage cell stimulation activities of irradiated β-glucan were higher than that of non-irradiated β-glucan. In addition, the oral administration of gamma-irradiated β-glucan significantly increased the proliferation and cytokine (IFN-γ and IL-2) release of spleen and Peyer's patch cells compared with non-irradiated β-glucan. In conclusion, gamma irradiation could be used as an effective method for the production of depolymerized β-glucan improved functional property such as immunomodulatory activity.

Effects of High Dietary HEME Iron and Radiation on Cardiovascular Function

NASA Technical Reports Server (NTRS)

Westby, Christian M.; Brown, A. K.; Platts, S. H.

2012-01-01

The radiation related health risks to astronauts is of particular concern to NASA. Data support that exposure to radiation is associated with a number of disorders including a heightened risk for cardiovascular diseases. Independent of radiation, altered nutrient status (e.g. high dietary iron) also increases ones risk for cardiovascular disease. However, it is unknown whether exposure to radiation in combination with high dietary iron further increases ones cardiovascular risk. The intent of our proposal is to generate compulsory data examining the combined effect of radiation exposure and iron overload on sensitivity to radiation injury to address HRP risks: 1) Risk Factor of Inadequate Nutrition; 2) Risk of Cardiac Rhythm Problems; and 3) Risk of Degenerative Tissue or other Health Effects from Space Radiation. Towards our goal we propose two distinct pilot studies using the following specific aims: Vascular Aim 1: To determine the short-term consequences of the independent and combined effects of exposure to gamma radiation and elevated body iron stores on measures of endothelial function and cell viability and integrity. We hypothesize that animals that have high body iron stores and are exposed to gamma radiation will show a greater reduction in endothelial dependent nitric oxid production and larger pathological changes in endothelial integrity than animals that have only 1 of those treatments (either high iron stores or exposure to gamma radiation). Vascular Aim 2: Identify and compare the effects of gamma radiation and elevated body iron stores on the genetic and epigenetic regulation of proteins associated with endothelial cell function. We hypothesize that modifications of epigenetic control and posttranslational expression of proteins associated with endothelial cell function will be differentially altered in rats with high body iron stores and exposed to gamma radiation compared to rats with only 1 type of treatment. Cardiac Aim 1: To determine the short-term consequences of the independent and combined effects of gamma radiation and elevated body iron stores on measures of cardiac structure. We hypothesize that modifications to cardiac structure and function will be greater in rats with high body iron stores and exposed to gamma radiation than in rats that have only 1 of those treatments. Cardiac Aim 2: Identify and compare the effects of gamma radiation and elevated body iron stores on the genetic and epigenetic regulation of proteins associated with cardiac structure and function. We hypothesize that modifications of epigenetic control and posttranslational expression of proteins associated with cardiac contractile function will be differentially altered in rats with high body iron stores and exposed to gamma radiation compared to rats with only 1 type of treatment.

Improvement of color and physiological properties of tuna-processing by-product by gamma irradiation

NASA Astrophysics Data System (ADS)

Choi, Jong-il; Kim, Hyun-Joo; Kim, Jae-Hun; Song, Beom-Seok; Chun, Byeong-Soo; Ahn, Dong-Hyun; Byun, Myung-Woo; Lee, Ju-Woon

2009-07-01

Although the by-products from fishery industry had many nutrients, it is being wasted or only used as bacteria media. In this study, the effect of a gamma irradiation on the cooking drips of Thunnus thynnus (CDT) was investigated to examine the possible use of the cooking drips as a functional material for food and cosmetic composition. Total aerobic bacteria, and yeasts/molds from CDT were detected at the level of 2.79 and 2.58 Log CFU/mL, respectively. But, CDT was efficiently sterilized by a gamma irradiation at a low dose of 1 kGy. The Hunter L* value of the gamma-irradiated ethanol extract of CDT was increased, and the a* and b* values were decreased compared to the non-irradiated extract, showing color improvement. Antioxidant activity of the ethanol extract of CDT was increased by a gamma irradiation depending on the irradiation dose. The increased contents of polyphenolic compounds and proteins in CDT extract by gamma irradiation may be the reason of the increased biological activity. These results suggested that the wasted cooking drips can be successfully used as functional components with gamma irradiation treatment.

Spectral Signatures of Feedforward and Recurrent Circuitry in Monkey Area MT.

PubMed

Solomon, Selina S; Morley, John W; Solomon, Samuel G

2017-05-01

Recordings of local field potential (LFP) in the visual cortex can show rhythmic activity at gamma frequencies (30-100 Hz). While the gamma rhythms in the primary visual cortex have been well studied, the structural and functional characteristics of gamma rhythms in extrastriate visual cortex are less clear. Here, we studied the spatial distribution and functional specificity of gamma rhythms in extrastriate middle temporal (MT) area of visual cortex in marmoset monkeys. We found that moving gratings induced narrowband gamma rhythms across cortical layers that were coherent across much of area MT. Moving dot fields instead induced a broadband increase in LFP in middle and upper layers, with weaker narrowband gamma rhythms in deeper layers. The stimulus dependence of LFP response in middle and upper layers of area MT appears to reflect the presence (gratings) or absence (dot fields and other textures) of strongly oriented contours. Our results suggest that gamma rhythms in these layers are propagated from earlier visual cortex, while those in the deeper layers may emerge in area MT. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Translational Bounds for Factorial n and the Factorial Polynomial

ERIC Educational Resources Information Center

Mahmood, Munir; Edwards, Phillip

2009-01-01

During the period 1729-1826 Bernoulli, Euler, Goldbach and Legendre developed expressions for defining and evaluating "n"! and the related gamma function. Expressions related to "n"! and the gamma function are a common feature in computer science and engineering applications. In the modern computer age people live in now, two common tests to…

Cross-frequency synchronization connects networks of fast and slow oscillations during visual working memory maintenance

PubMed Central

Siebenhühner, Felix; Wang, Sheng H; Palva, J Matias; Palva, Satu

2016-01-01

Neuronal activity in sensory and fronto-parietal (FP) areas underlies the representation and attentional control, respectively, of sensory information maintained in visual working memory (VWM). Within these regions, beta/gamma phase-synchronization supports the integration of sensory functions, while synchronization in theta/alpha bands supports the regulation of attentional functions. A key challenge is to understand which mechanisms integrate neuronal processing across these distinct frequencies and thereby the sensory and attentional functions. We investigated whether such integration could be achieved by cross-frequency phase synchrony (CFS). Using concurrent magneto- and electroencephalography, we found that CFS was load-dependently enhanced between theta and alpha–gamma and between alpha and beta-gamma oscillations during VWM maintenance among visual, FP, and dorsal attention (DA) systems. CFS also connected the hubs of within-frequency-synchronized networks and its strength predicted individual VWM capacity. We propose that CFS integrates processing among synchronized neuronal networks from theta to gamma frequencies to link sensory and attentional functions. DOI: http://dx.doi.org/10.7554/eLife.13451.001 PMID:27669146

Survival Bayesian Estimation of Exponential-Gamma Under Linex Loss Function

NASA Astrophysics Data System (ADS)

Rizki, S. W.; Mara, M. N.; Sulistianingsih, E.

2017-06-01

This paper elaborates a research of the cancer patients after receiving a treatment in cencored data using Bayesian estimation under Linex Loss function for Survival Model which is assumed as an exponential distribution. By giving Gamma distribution as prior and likelihood function produces a gamma distribution as posterior distribution. The posterior distribution is used to find estimatior {\\hat{λ }}BL by using Linex approximation. After getting {\\hat{λ }}BL, the estimators of hazard function {\\hat{h}}BL and survival function {\\hat{S}}BL can be found. Finally, we compare the result of Maximum Likelihood Estimation (MLE) and Linex approximation to find the best method for this observation by finding smaller MSE. The result shows that MSE of hazard and survival under MLE are 2.91728E-07 and 0.000309004 and by using Bayesian Linex worths 2.8727E-07 and 0.000304131, respectively. It concludes that the Bayesian Linex is better than MLE.

Measuring bovine gamma delta T cell function at the site of Mycobacterium bovis infection

USDA-ARS?s Scientific Manuscript database

Bovine gamma delta T cells are amongst the first cells to accumulate at the site of Mycobacterium bovis infection; however, their role in the developing lesion remains unclear. We utilized transcriptomics analysis, in situ hybridization, and a macrophage/gamma delta T cell co-culture system to eluc...

Phosphorylation of Nephrin Triggers Ca2+ Signaling by Recruitment and Activation of Phospholipase C-{gamma}1.

PubMed

Harita, Yutaka; Kurihara, Hidetake; Kosako, Hidetaka; Tezuka, Tohru; Sekine, Takashi; Igarashi, Takashi; Ohsawa, Ikuroh; Ohta, Shigeo; Hattori, Seisuke

2009-03-27

A specialized intercellular junction between podocytes, known as the slit diaphragm (SD), forms the essential structural frame-work for glomerular filtration in the kidney. In addition, mounting evidence demonstrates that the SD also plays a crucial role as a signaling platform in physiological and pathological states. Nephrin, the major component of the SD, is tyrosine-phosphorylated by a Src family tyrosine kinase, Fyn, in developing or injured podocytes, recruiting Nck to Nephrin via its Src homology 2 domain to regulate dynamic actin remodeling. Dysregulated Ca(2+) homeostasis has also been implicated in podocyte damage, but the mechanism of how podocytes respond to injury is largely unknown. Here we have identified phospholipase C-gamma1 (PLC-gamma1) as a novel phospho-Nephrin-binding protein. When HEK293T cells expressing a chimeric protein consisting of CD8 and Nephrin cytoplasmic domain (CD) were treated with anti-CD8 and anti-mouse antibodies, clustering of Nephrin and phosphorylation of Nephrin-CD were induced. Upon this clustering, PLC-gamma1 was bound to phosphorylated Nephrin Tyr-1204, which induced translocation of PLC-gamma1 from cytoplasm to the CD8/Nephrin cluster on the plasma membrane. The recruitment of PLC-gamma1 to Nephrin activated PLC-gamma1, as detected by phosphorylation of PLC-gamma1 Tyr-783 and increase in inositol 1,4,5-trisphosphate level. We also found that Nephrin Tyr-1204 phosphorylation triggers the Ca(2+) response in a PLC-gamma1-dependent fashion. Furthermore, PLC-gamma1 is significantly phosphorylated in injured podocytes in vivo. Given the profound effect of PLC-gamma in diverse cellular functions, regulation of the Ca(2+) signaling by Nephrin may be important in modulating the glomerular filtration barrier function.

Human epidermal langerhans cells express the immunoregulatory enzyme indoleamine 2,3-dioxygenase.

PubMed

von Bubnoff, Dagmar; Bausinger, Huguette; Matz, Heike; Koch, Susanne; Häcker, Georg; Takikawa, Osamu; Bieber, Thomas; Hanau, Daniel; de la Salle, Henri

2004-08-01

Langerhans cells (LC) are a special subset of dendritic cells integrating cutaneous immunity. The study of LC function is of major interest not only for efforts of vaccine design and immunotherapy but also for gaining an insight into the pathogenesis of immune-mediated cutaneous diseases and neoplasias. Recently, defined antigen-presenting cells were described that express indoleamine 2,3-dioxygenase (IDO) and inhibit T cell proliferation in vitro and in vivo. Here, we show that stimulation with interferon-gamma (IFN-gamma) induces the expression of functionally active IDO in highly purified human epidermal LC. The induction of IDO after stimulation of LC with IFN-gamma seems to follow a defined kinetic with rapid upregulation followed by a downregulation after about 24 h of culture. Accordingly, proliferation of T cells induced by anti-CD3 antibodies was modulated by supernatants of IFN-gamma-activated human epidermal LC. Importantly, downregulation of T cell proliferation by supernatants of 24 h IFN-gamma-activated LC was prevented by inhibition of IDO. These results indicate that LC not only have the capacity to stimulate but also to inhibit T cells, and suggest that LC possess an immunoregulatory function in promoting T cell tolerance by production of IDO.

Probability density function of the intensity of a laser beam propagating in the maritime environment.

PubMed

Korotkova, Olga; Avramov-Zamurovic, Svetlana; Malek-Madani, Reza; Nelson, Charles

2011-10-10

A number of field experiments measuring the fluctuating intensity of a laser beam propagating along horizontal paths in the maritime environment is performed over sub-kilometer distances at the United States Naval Academy. Both above the ground and over the water links are explored. Two different detection schemes, one photographing the beam on a white board, and the other capturing the beam directly using a ccd sensor, gave consistent results. The probability density function (pdf) of the fluctuating intensity is reconstructed with the help of two theoretical models: the Gamma-Gamma and the Gamma-Laguerre, and compared with the intensity's histograms. It is found that the on-ground experimental results are in good agreement with theoretical predictions. The results obtained above the water paths lead to appreciable discrepancies, especially in the case of the Gamma-Gamma model. These discrepancies are attributed to the presence of the various scatterers along the path of the beam, such as water droplets, aerosols and other airborne particles. Our paper's main contribution is providing a methodology for computing the pdf function of the laser beam intensity in the maritime environment using field measurements.

Effects of gamma irradiation on the protein characteristics and functional properties of sesame (Sesamum indicum L.) seeds

NASA Astrophysics Data System (ADS)

Hassan, Amro B.; Mahmoud, Nagat S.; Elmamoun, Khalid; Adiamo, Oladipupo Q.; Mohamed Ahmed, Isam A.

2018-03-01

This study was aimed at investigating the effect of gamma irradiation at various doses (0.5, 1.0, 1.5 and 2.0 kGy) on protein characteristics and functional properties of sesame seeds. Gamma radiation at high doses (>1.0 kGy) significantly (P ≤ 0.05) increased globulin and albumin fractions of sesame protein. Concomitant (P ≤ 0.05) increase of in-vitro protein digestibility was noticed in irradiated sesame flour compared to non-radiated sample. Maximum protein solubility was observed in sesame flour irradiated at 1.0 kGy. SDS-PAGE electrophoretic patterns of total sesame protein were not affected by irradiation process. Significant enhancement (P ≤ 0.05) in emulsification capacity (EC) and emulsion stability (ES) was recorded after irradiation at a dose level of 1.0 and 1.5-2.0 kGy, respectively. Foaming capacity reached a significantly maximum value in sesame flour irradiated at 1.0 kGy while foaming stability was not significantly affected by gamma irradiation. It can be concluded that gamma radiation enhances the protein and functional properties of sesame flour and thus can be employed as an effective method of preserving sesame flour and its products.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lu, Jinghua; Marnell, Lorraine L.; Marjon, Kristopher D.

Pentraxins are a family of ancient innate immune mediators conserved throughout evolution. The classical pentraxins include serum amyloid P component (SAP) and C-reactive protein, which are two of the acute-phase proteins synthesized in response to infection. Both recognize microbial pathogens and activate the classical complement pathway through C1q. More recently, members of the pentraxin family were found to interact with cell-surface Fc{gamma} receptors (Fc{gamma}R) and activate leukocyte-mediated phagocytosis. Here we describe the structural mechanism for pentraxin's binding to Fc{gamma}R and its functional activation of Fc{gamma}R-mediated phagocytosis and cytokine secretion. The complex structure between human SAP and Fc{gamma}RIIa reveals a diagonallymore » bound receptor on each SAP pentamer with both D1 and D2 domains of the receptor contacting the ridge helices from two SAP subunits. The 1:1 stoichiometry between SAP and Fc{gamma}RIIa infers the requirement for multivalent pathogen binding for receptor aggregation. Mutational and binding studies show that pentraxins are diverse in their binding specificity for Fc{gamma}R isoforms but conserved in their recognition structure. The shared binding site for SAP and IgG results in competition for Fc{gamma}R binding and the inhibition of immune-complex-mediated phagocytosis by soluble pentraxins. These results establish antibody-like functions for pentraxins in the Fc{gamma}R pathway, suggest an evolutionary overlap between the innate and adaptive immune systems, and have new therapeutic implications for autoimmune diseases.« less

More Gamma More Predictions: Gamma-Synchronization as a Key Mechanism for Efficient Integration of Classical Receptive Field Inputs with Surround Predictions

PubMed Central

Vinck, Martin; Bosman, Conrado A.

2016-01-01

During visual stimulation, neurons in visual cortex often exhibit rhythmic and synchronous firing in the gamma-frequency (30–90 Hz) band. Whether this phenomenon plays a functional role during visual processing is not fully clear and remains heavily debated. In this article, we explore the function of gamma-synchronization in the context of predictive and efficient coding theories. These theories hold that sensory neurons utilize the statistical regularities in the natural world in order to improve the efficiency of the neural code, and to optimize the inference of the stimulus causes of the sensory data. In visual cortex, this relies on the integration of classical receptive field (CRF) data with predictions from the surround. Here we outline two main hypotheses about gamma-synchronization in visual cortex. First, we hypothesize that the precision of gamma-synchronization reflects the extent to which CRF data can be accurately predicted by the surround. Second, we hypothesize that different cortical columns synchronize to the extent that they accurately predict each other’s CRF visual input. We argue that these two hypotheses can account for a large number of empirical observations made on the stimulus dependencies of gamma-synchronization. Furthermore, we show that they are consistent with the known laminar dependencies of gamma-synchronization and the spatial profile of intercolumnar gamma-synchronization, as well as the dependence of gamma-synchronization on experience and development. Based on our two main hypotheses, we outline two additional hypotheses. First, we hypothesize that the precision of gamma-synchronization shows, in general, a negative dependence on RF size. In support, we review evidence showing that gamma-synchronization decreases in strength along the visual hierarchy, and tends to be more prominent in species with small V1 RFs. Second, we hypothesize that gamma-synchronized network dynamics facilitate the emergence of spiking output that is particularly information-rich and sparse. PMID:27199684

Gamma ray spectroscopy in astrophysics: Solar gamma ray astronomy on solar maximum mission. [experimental design

NASA Technical Reports Server (NTRS)

Forrest, D. J.

1978-01-01

The SMM gamma ray experiment and the important scientific capabilities of the instrument are discussed. The flare size detectable as a function of spectrum integration time was studied. A preliminary estimate indicates that a solar gamma ray line at 4.4 MeV one-fifth the intensity of that believed to have been emitted on 4 August 1972 can be detected in approximately 1000 sec with a confidence level of 99%.

Theta-Modulated Gamma-Band Synchronization Among Activated Regions During a Verb Generation Task

PubMed Central

Doesburg, Sam M.; Vinette, Sarah A.; Cheung, Michael J.; Pang, Elizabeth W.

2012-01-01

Expressive language is complex and involves processing within a distributed network of cortical regions. Functional MRI and magnetoencephalography (MEG) have identified brain areas critical for expressive language, but how these regions communicate across the network remains poorly understood. It is thought that synchronization of oscillations between neural populations, particularly at a gamma rate (>30 Hz), underlies functional integration within cortical networks. Modulation of gamma rhythms by theta-band oscillations (4–8 Hz) has been proposed as a mechanism for the integration of local cell coalitions into large-scale networks underlying cognition and perception. The present study tested the hypothesis that these oscillatory mechanisms of functional integration were present within the expressive language network. We recorded MEG while subjects performed a covert verb generation task. We localized activated cortical regions using beamformer analysis, calculated inter-regional phase locking between activated areas, and measured modulation of inter-regional gamma synchronization by theta phase. The results show task-dependent gamma-band synchronization among regions activated during the performance of the verb generation task, and we provide evidence that these transient and periodic instances of high-frequency connectivity were modulated by the phase of cortical theta oscillations. These findings suggest that oscillatory synchronization and cross-frequency interactions are mechanisms for functional integration among distributed brain areas supporting expressive language processing. PMID:22707946

The gamma-ray luminosity function of millisecond pulsars and implications for the GeV excess

DOE PAGES

Hooper, Dan; Mohlabeng, Gopolang

2016-03-29

It has been proposed that a large population of unresolved millisecond pulsars (MSPs) could potentially account for the excess of GeV-scale gamma-rays observed from the region surrounding the Galactic Center. The viability of this scenario depends critically on the gamma-ray luminosity function of this source population, which determines how many MSPs Fermi should have already detected as resolved point sources. In this paper, we revisit the gamma-ray luminosity function of MSPs, without relying on uncertain distance measurements. Our determination, based on a comparison of models with the observed characteristics of the MSP population, suggests that Fermi should have already detectedmore » a significant number of sources associated with such a hypothesized Inner Galaxy population. As a result, we cannot rule out a scenario in which the MSPs residing near the Galactic Center are systematically less luminous than those present in the Galactic Plane or within globular clusters.« less

Conversion of the LXR-agonist TO-901317--from inverse to normal modulation of gamma-secretase by addition of a carboxylic acid and a lipophilic anchor.

PubMed

Narlawar, Rajeshwar; Baumann, Karlheinz; Czech, Christian; Schmidt, Boris

2007-10-01

TO-901317, a LXR agonist, is an inverse modulator of Alzheimer's disease associated gamma-secretase. We synthesized TO-901317 analogous compound but replaced the hexafluorocarbinol moiety by an oxyacetic acid functionality and hypothesized that the replacement would change the mode of action from an inverse modulation to normal modulation of gamma-secretase. As anticipated, acid 9 was found to be an effective modulator of gamma-secretase and displayed activity at low micromolar concentration. This significant modification can be applied to several inverse gamma-secretase modulators. Such modulators may preserve the cleavage of other gamma-secretase substrates such as Notch.

Silicon/HfO{sub 2} interface: Effects of gamma irradiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maurya, Savita

2016-05-23

Quality of MOS devices is a strong function of substrate and oxide interface. In this work we have studied how gamma photon irradiation affects the interface of a 13 nm thick, atomic layer deposited hafnium dioxide deposited on silicon wafer. CV and GV measurements have been done for pristine and irradiated samples to quantify the effect of gamma photon irradiation. Gamma photon irradiation not only introduces positive charge in the oxide and at the interface of Si/HfO{sub 2} interface but also induce phase change of oxide layer. Maximum oxide capacitances are affected by gamma photon irradiation.

Theory and Performance of AIMS for Active Interrogation

NASA Astrophysics Data System (ADS)

Walters, William J.; Royston, Katherine E. K.; Haghighat, Alireza

2014-06-01

A hybrid Monte Carlo and deterministic methodology has been developed for application to active interrogation systems. The methodology consists of four steps: i) determination of neutron flux distribution due to neutron source transport and subcritical multiplication; ii) generation of gamma source distribution from (n, γ) interactions; iii) determination of gamma current at a detector window; iv) detection of gammas by the detector. This paper discusses the theory and results of the first three steps for the case of a cargo container with a sphere of HEU in third-density water. In the first step, a response-function formulation has been developed to calculate the subcritical multiplication and neutron flux distribution. Response coefficients are pre-calculated using the MCNP5 Monte Carlo code. The second step uses the calculated neutron flux distribution and Bugle-96 (n, γ) cross sections to find the resulting gamma source distribution. Finally, in the third step the gamma source distribution is coupled with a pre-calculated adjoint function to determine the gamma flux at a detector window. A code, AIMS (Active Interrogation for Monitoring Special-Nuclear-materials), has been written to output the gamma current for an source-detector assembly scanning across the cargo using the pre-calculated values and takes significantly less time than a reference MCNP5 calculation.

Stimulus-induced dissociation of neuronal firing rates and local field potential gamma power and its relationship to the blood oxygen level-dependent signal in macaque primary visual cortex

PubMed Central

Bartolo, M J; Gieselmann, M A; Vuksanovic, V; Hunter, D; Sun, L; Chen, X; Delicato, L S; Thiele, A

2011-01-01

The functional magnetic resonance imaging (fMRI) blood oxygenation level-dependent (BOLD) signal is regularly used to assign neuronal activity to cognitive function. Recent analyses have shown that the local field potential (LFP) gamma power is a better predictor of the fMRI BOLD signal than spiking activity. However, LFP gamma power and spiking activity are usually correlated, clouding the analysis of the neural basis of the BOLD signal. We show that changes in LFP gamma power and spiking activity in the primary visual cortex (V1) of the awake primate can be dissociated by using grating and plaid pattern stimuli, which differentially engage surround suppression and cross-orientation inhibition/facilitation within and between cortical columns. Grating presentation yielded substantial V1 LFP gamma frequency oscillations and significant multi-unit activity. Plaid pattern presentation significantly reduced the LFP gamma power while increasing population multi-unit activity. The fMRI BOLD activity followed the LFP gamma power changes, not the multi-unit activity. Inference of neuronal activity from the fMRI BOLD signal thus requires detailed a priori knowledge of how different stimuli or tasks activate the cortical network. PMID:22081989

Development of MMC Gamma Detectors for Precise Characterization of Uranium Isotopes

NASA Astrophysics Data System (ADS)

Kim, G. B.; Flynn, C. C.; Kempf, S.; Gastaldo, L.; Fleischmann, A.; Enss, C.; Friedrich, S.

2018-06-01

Precise nuclear data from radioactive decays are important for the accurate non-destructive assay of fissile materials in nuclear safeguards. We are developing high energy resolution gamma detectors based on metallic magnetic calorimeters (MMCs) to accurately measure gamma-ray energies and branching ratios of uranium isotopes. Our MMC gamma detectors exhibit good linearity, reproducibility and a consistent response function for low energy gamma-rays. We illustrate the capabilities of MMCs to improve literature values of nuclear data with an analysis of gamma spectra of U-233. In this context, we also improve the value of the energy for the single gamma-ray of the U-233 daughter Ra-225 by over an order of magnitude from 40.09 ± 0.05 to 40.0932 ± 0.0007 keV.

Dual mode stereotactic localization method and application

DOEpatents

Keppel, Cynthia E.; Barbosa, Fernando Jorge; Majewski, Stanislaw

2002-01-01

The invention described herein combines the structural digital X-ray image provided by conventional stereotactic core biopsy instruments with the additional functional metabolic gamma imaging obtained with a dedicated compact gamma imaging mini-camera. Before the procedure, the patient is injected with an appropriate radiopharmaceutical. The radiopharmaceutical uptake distribution within the breast under compression in a conventional examination table expressed by the intensity of gamma emissions is obtained for comparison (co-registration) with the digital mammography (X-ray) image. This dual modality mode of operation greatly increases the functionality of existing stereotactic biopsy devices by yielding a much smaller number of false positives than would be produced using X-ray images alone. The ability to obtain both the X-ray mammographic image and the nuclear-based medicine gamma image using a single device is made possible largely through the use of a novel, small and movable gamma imaging camera that permits its incorporation into the same table or system as that currently utilized to obtain X-ray based mammographic images for localization of lesions.

Chromosomal localization and partial genomic structure of the human peroxisome proliferator activated receptor-gamma (hPPAR gamma) gene.

PubMed

Beamer, B A; Negri, C; Yen, C J; Gavrilova, O; Rumberger, J M; Durcan, M J; Yarnall, D P; Hawkins, A L; Griffin, C A; Burns, D K; Roth, J; Reitman, M; Shuldiner, A R

1997-04-28

We determined the chromosomal localization and partial genomic structure of the coding region of the human PPAR gamma gene (hPPAR gamma), a nuclear receptor important for adipocyte differentiation and function. Sequence analysis and long PCR of human genomic DNA with primers that span putative introns revealed that intron positions and sizes of hPPAR gamma are similar to those previously determined for the mouse PPAR gamma gene[13]. Fluorescent in situ hybridization localized hPPAR gamma to chromosome 3, band 3p25. Radiation hybrid mapping with two independent primer pairs was consistent with hPPAR gamma being within 1.5 Mb of marker D3S1263 on 3p25-p24.2. These sequences of the intron/exon junctions of the 6 coding exons shared by hPPAR gamma 1 and hPPAR gamma 2 will facilitate screening for possible mutations. Furthermore, D3S1263 is a suitable polymorphic marker for linkage analysis to evaluate PPAR gamma's potential contribution to genetic susceptibility to obesity, lipoatrophy, insulin resistance, and diabetes.

GAMSOR: Gamma Source Preparation and DIF3D Flux Solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, M. A.; Lee, C. H.; Hill, R. N.

2017-06-28

Nuclear reactors that rely upon the fission reaction have two modes of thermal energy deposition in the reactor system: neutron absorption and gamma absorption. The gamma rays are typically generated by neutron capture reactions or during the fission process which means the primary driver of energy production is of course the neutron interaction. In conventional reactor physics methods, the gamma heating component is ignored such that the gamma absorption is forced to occur at the gamma emission site. For experimental reactor systems like EBR-II and FFTF, the placement of structural pins and assemblies internal to the core leads to problemsmore » with power heating predictions because there is no fission power source internal to the assembly to dictate a spatial distribution of the power. As part of the EBR-II support work in the 1980s, the GAMSOR code was developed to assist analysts in calculating the gamma heating. The GAMSOR code is a modified version of DIF3D and actually functions within a sequence of DIF3D calculations. The gamma flux in a conventional fission reactor system does not perturb the neutron flux and thus the gamma flux calculation can be cast as a fixed source problem given a solution to the steady state neutron flux equation. This leads to a sequence of DIF3D calculations, called the GAMSOR sequence, which involves solving the neutron flux, then the gamma flux, and then combining the results to do a summary edit. In this manuscript, we go over the GAMSOR code and detail how it is put together and functions. We also discuss how to setup the GAMSOR sequence and input for each DIF3D calculation in the GAMSOR sequence.« less

Increased production of functional recombinant human clotting factor IX by baby hamster kidney cells engineered to overexpress VKORC1, the vitamin K 2,3-epoxide-reducing enzyme of the vitamin K cycle.

PubMed

Wajih, Nadeem; Hutson, Susan M; Owen, John; Wallin, Reidar

2005-09-09

Some recombinant vitamin K-dependent blood coagulation factors (factors VII, IX, and protein C) have become valuable pharmaceuticals in the treatment of bleeding complications and sepsis. Because of their vitamin K-dependent post-translational modification, their synthesis by eukaryotic cells is essential. The eukaryotic cell harbors a vitamin K-dependent gamma-carboxylation system that converts the proteins to gamma-carboxyglutamic acid-containing proteins. However, the system in eukaryotic cells has limited capacity, and cell lines overexpressing vitamin K-dependent clotting factors produce only a fraction of the recombinant proteins as fully gamma-carboxylated, physiologically competent proteins. In this work we have used recombinant human factor IX (r-hFIX)-producing baby hamster kidney (BHK) cells, engineered to stably overexpress various components of the gamma-carboxylation system of the cell, to determine whether increased production of functional r-hFIX can be accomplished. All BHK cell lines secreted r-hFIX into serum-free medium. Overexpression of gamma-carboxylase is shown to inhibit production of functional r-hFIX. On the other hand, cells overexpressing VKORC1, the reduced vitamin K cofactor-producing enzyme of the vitamin K-dependent gamma-carboxylation system, produced 2.9-fold more functional r-hFIX than control BHK cells. The data are consistent with the notion that VKORC1 is the rate-limiting step in the system and is a key regulatory protein in synthesis of active vitamin K-dependent proteins. The data suggest that overexpression of VKORC1 can be utilized for increased cellular production of recombinant vitamin K-dependent proteins.

GABA level, gamma oscillation, and working memory performance in schizophrenia

PubMed Central

Chen, Chi-Ming A.; Stanford, Arielle D.; Mao, Xiangling; Abi-Dargham, Anissa; Shungu, Dikoma C.; Lisanby, Sarah H.; Schroeder, Charles E.; Kegeles, Lawrence S.

2014-01-01

A relationship between working memory impairment, disordered neuronal oscillations, and abnormal prefrontal GABA function has been hypothesized in schizophrenia; however, in vivo GABA measurements and gamma band neural synchrony have not yet been compared in schizophrenia. This case–control pilot study (N = 24) compared baseline and working memory task-induced neuronal oscillations acquired with high-density electroencephalograms (EEGs) to GABA levels measured in vivo with magnetic resonance spectroscopy. Working memory performance, baseline GABA level in the left dorsolateral prefrontal cortex (DLPFC), and measures of gamma oscillations from EEGs at baseline and during a working memory task were obtained. A major limitation of this study is a relatively small sample size for several analyses due to the integration of diverse methodologies and participant compliance. Working memory performance was significantly lower for patients than for controls. During the working memory task, patients (n = 7) had significantly lower amplitudes in gamma oscillations than controls (n = 9). However, both at rest and across working memory stages, there were significant correlations between gamma oscillation amplitude and left DLPFC GABA level. Peak gamma frequency during the encoding stage of the working memory task (n = 16) significantly correlated with GABA level and working memory performance. Despite gamma band amplitude deficits in patients across working memory stages, both baseline and working memory-induced gamma oscillations showed strong dependence on baseline GABA levels in patients and controls. These findings suggest a critical role for GABA function in gamma band oscillations, even under conditions of system and cognitive impairments as seen in schizophrenia. PMID:24749063

GABA level, gamma oscillation, and working memory performance in schizophrenia.

PubMed

Chen, Chi-Ming A; Stanford, Arielle D; Mao, Xiangling; Abi-Dargham, Anissa; Shungu, Dikoma C; Lisanby, Sarah H; Schroeder, Charles E; Kegeles, Lawrence S

2014-01-01

A relationship between working memory impairment, disordered neuronal oscillations, and abnormal prefrontal GABA function has been hypothesized in schizophrenia; however, in vivo GABA measurements and gamma band neural synchrony have not yet been compared in schizophrenia. This case-control pilot study (N = 24) compared baseline and working memory task-induced neuronal oscillations acquired with high-density electroencephalograms (EEGs) to GABA levels measured in vivo with magnetic resonance spectroscopy. Working memory performance, baseline GABA level in the left dorsolateral prefrontal cortex (DLPFC), and measures of gamma oscillations from EEGs at baseline and during a working memory task were obtained. A major limitation of this study is a relatively small sample size for several analyses due to the integration of diverse methodologies and participant compliance. Working memory performance was significantly lower for patients than for controls. During the working memory task, patients (n = 7) had significantly lower amplitudes in gamma oscillations than controls (n = 9). However, both at rest and across working memory stages, there were significant correlations between gamma oscillation amplitude and left DLPFC GABA level. Peak gamma frequency during the encoding stage of the working memory task (n = 16) significantly correlated with GABA level and working memory performance. Despite gamma band amplitude deficits in patients across working memory stages, both baseline and working memory-induced gamma oscillations showed strong dependence on baseline GABA levels in patients and controls. These findings suggest a critical role for GABA function in gamma band oscillations, even under conditions of system and cognitive impairments as seen in schizophrenia.

Contributions of Torpedo nicotinic acetylcholine receptor gamma Trp-55 and delta Trp-57 to agonist and competitive antagonist function.

PubMed

Xie, Y; Cohen, J B

2001-01-26

Results of affinity-labeling studies and mutational analyses provide evidence that the agonist binding sites of the nicotinic acetylcholine receptor (nAChR) are located at the alpha-gamma and alpha-delta subunit interfaces. For Torpedo nAChR, photoaffinity-labeling studies with the competitive antagonist d-[(3)H]tubocurarine (dTC) identified two tryptophans, gammaTrp-55 and deltaTrp-57, as the primary sites of photolabeling in the non-alpha subunits. To characterize the importance of gammaTrp-55 and deltaTrp-57 to the interactions of agonists and antagonists, Torpedo nAChRs were expressed in Xenopus oocytes, and equilibrium binding assays and electrophysiological recordings were used to examine the functional consequences when either or both tryptophans were mutated to leucine. Neither substitution altered the equilibrium binding of dTC. However, the deltaW57L and gammaW55L mutations decreased acetylcholine (ACh) binding affinity by 20- and 7,000-fold respectively. For the wild-type, gammaW55L, and deltaW57L nAChRs, the concentration dependence of channel activation was characterized by Hill coefficients of 1.8, 1.1, and 1.7. For the gammaW55L mutant, dTC binding at the alpha-gamma site acts not as a competitive antagonist but as a coactivator or partial agonist. These results establish that interactions with gamma Trp-55 of the Torpedo nAChR play a crucial role in agonist binding and in the agonist-induced conformational changes that lead to channel opening.

Differences in gamma frequencies across visual cortex restrict their possible use in computation.

PubMed

Ray, Supratim; Maunsell, John H R

2010-09-09

Neuronal oscillations in the gamma band (30-80 Hz) have been suggested to play a central role in feature binding or establishing channels for neural communication. For these functions, the gamma rhythm frequency must be consistent across neural assemblies encoding the features of a stimulus. Here we test the dependence of gamma frequency on stimulus contrast in V1 cortex of awake behaving macaques and show that gamma frequency increases monotonically with contrast. Changes in stimulus contrast over time leads to a reliable gamma frequency modulation on a fast timescale. Further, large stimuli whose contrast varies across space generate gamma rhythms at significantly different frequencies in simultaneously recorded neuronal assemblies separated by as little as 400 microm, making the gamma rhythm a poor candidate for binding or communication, at least in V1. Instead, our results suggest that the gamma rhythm arises from local interactions between excitation and inhibition. 2010 Elsevier Inc. All rights reserved.

Gold-catalyzed and N-iodosuccinimide-mediated cyclization of gamma-substituted allenamides.

PubMed

Hyland, Christopher J T; Hegedus, Louis S

2006-10-27

Chiral gamma-substituted allenamides have been shown to undergo efficient gold-catalyzed and N-iodosuccinimide-mediated cyclization to highly functionalized dihydrofurans. These reactions proceed rapidly and without loss of stereochemistry.

Fear conditioning is associated with altered integration of PLC and ERK signaling in the hippocampus.

PubMed

Buckley, Colin T; Caldwell, Kevin K

2004-12-01

The extracellular signal-regulated protein kinases (ERKs) are proline-directed, serine/threonine kinases that regulate a variety of cellular functions, including proliferation, differentiation, and plasticity. In the present report, we provide evidence that ERK2 and phosphatidylinositol-specific phospholipase C (PLC)-beta and -gamma isozymes interact in the rat hippocampal formation. We found that anti-PLC-beta1a, -beta2, -beta4, -gamma1 and -gamma2, but not -beta3, immune complexes isolated from rat hippocampal formation postnuclear fractions contain anti-ERK2 immunoreactivity. Further, we show that PLC catalytic activity is associated with anti-ERK2 immunoprecipitates isolated from the hippocampal formation, and that the amount of enzyme activity is significantly increased following fear-conditioned learning. The observed interactions may be mediated by consensus sequences conforming to an ERK2 docking site, termed a D-domain, that we identified in PLC-beta1a, -beta2, -beta4 -gamma1 and -gamma2. Based on these results, we propose that PLC-beta and PLC-gamma isozymes form signaling complexes with ERK2 in rat brain, and these complexes play critical roles in learning and memory, as well as a variety of other neuronal functions.

Structural and metabolic relationships between goldfish brain glycoproteins participating in functional plasticity of the central nervous system.

PubMed

Schmidt, R; Shashoua, V E

1983-03-01

Ependymins beta and gamma (MW 32,000 and 26,000 daltons) are two secreted goldfish brain glycoproteins that exhibit a specifically enhanced turnover rate when the animals successfully acquire a new pattern of swimming behaviour. Both proteins are bound identically to concanavalin A and can be isolated from brain extracellular fluid and from brain cytoplasm by lectin affinity chromatography. Radioimmunoassay data, using purified 125I-labeled ependymins and antisera directed against ependymin beta or ependymin gamma, show complete cross-reactivity between the two proteins. It is demonstrated by Scatchard-plot analysis that the antisera recognize identical immunological determinants in both proteins. The amino acid composition of the ependymins is similar, and several identical polypeptide fragments are obtained after limited proteolysis with Staphylococcus aureus protease. The proteins are capable of forming complexes of the compositions gamma 2, beta gamma, and beta 2. A protease present in the extracellular fluid of goldfish brain promotes proteolysis of ependymin beta to ependymin gamma. The finding that ependymin gamma is physiologically derived from ependymin beta suggests the possibility that ependymin beta might exert its biological function during consolidation of new behavioural patterns via smaller polypeptide fragments.

Study of near-stability nuclei populated as fission fragments in heavy-ion fusion reactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fotiadis, Nikolaos; Nelson, Ronald O; Devlin, Matthew

2010-01-01

Examples are presented to illustrate the power of prompt {gamma}-ray spectroscopy of fission fragments from compound nuclei with A {approx} 200 formed in fusion-evaporation reactions in experiments using the Gammasphere Ge-detector array. Complementary methods, such as Coulomb excitation and deep-inelastic processes, are also discussed. In other cases (n, xn{gamma}) reactions on stable isotopes have been used to establish neutron excitation functions for {gamma}-rays using a pulsed 'white'-neutron source, coupled to a high-energy-resolution germanium-detector array. The excitation functions can unambiguously assign {gamma}-rays to a specific reaction product. Results from all these methods bridge the gaps in the systematics of high-spin statesmore » between the neutron-deficient and neutron-rich nuclei. Results near shell closures should motivate new shell model calculations.« less

Neocortical 40 Hz oscillations during carbachol-induced rapid eye movement sleep and cataplexy.

PubMed

Torterolo, Pablo; Castro-Zaballa, Santiago; Cavelli, Matías; Chase, Michael H; Falconi, Atilio

2016-02-01

Higher cognitive functions require the integration and coordination of large populations of neurons in cortical and subcortical regions. Oscillations in the gamma band (30-45 Hz) of the electroencephalogram (EEG) have been involved in these cognitive functions. In previous studies, we analysed the extent of functional connectivity between cortical areas employing the 'mean squared coherence' analysis of the EEG gamma band. We demonstrated that gamma coherence is maximal during alert wakefulness and is almost absent during rapid eye movement (REM) sleep. The nucleus pontis oralis (NPO) is critical for REM sleep generation. The NPO is considered to exert executive control over the initiation and maintenance of REM sleep. In the cat, depending on the previous state of the animal, a single microinjection of carbachol (a cholinergic agonist) into the NPO can produce either REM sleep [REM sleep induced by carbachol (REMc)] or a waking state with muscle atonia, i.e. cataplexy [cataplexy induced by carbachol (CA)]. In the present study, in cats that were implanted with electrodes in different cortical areas to record polysomnographic activity, we compared the degree of gamma (30-45 Hz) coherence during REMc, CA and naturally-occurring behavioural states. Gamma coherence was maximal during CA and alert wakefulness. In contrast, gamma coherence was almost absent during REMc as in naturally-occurring REM sleep. We conclude that, in spite of the presence of somatic muscle paralysis, there are remarkable differences in cortical activity between REMc and CA, which confirm that EEG gamma (≈40 Hz) coherence is a trait that differentiates wakefulness from REM sleep. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Test of the Brink-Axel Hypothesis for the Pygmy Dipole Resonance

NASA Astrophysics Data System (ADS)

Martin, D.; von Neumann-Cosel, P.; Tamii, A.; Aoi, N.; Bassauer, S.; Bertulani, C. A.; Carter, J.; Donaldson, L.; Fujita, H.; Fujita, Y.; Hashimoto, T.; Hatanaka, K.; Ito, T.; Krugmann, A.; Liu, B.; Maeda, Y.; Miki, K.; Neveling, R.; Pietralla, N.; Poltoratska, I.; Ponomarev, V. Yu.; Richter, A.; Shima, T.; Yamamoto, T.; Zweidinger, M.

2017-11-01

The gamma strength function and level density of 1- states in 96Mo have been extracted from a high-resolution study of the (p → , p→ ' ) reaction at 295 MeV and extreme forward angles. By comparison with compound nucleus γ decay experiments, this allows a test of the generalized Brink-Axel hypothesis in the energy region of the pygmy dipole resonance. The Brink-Axel hypothesis is commonly assumed in astrophysical reaction network calculations and states that the gamma strength function in nuclei is independent of the structure of the initial and final state. The present results validate the Brink-Axel hypothesis for 96Mo and provide independent confirmation of the methods used to separate gamma strength function and level density in γ decay experiments.

Fieldable computer system for determining gamma-ray pulse-height distributions, flux spectra, and dose rates from Little Boy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moss, C.E.; Lucas, M.C.; Tisinger, E.W.

1984-01-01

Our system consists of a LeCroy 3500 data acquisition system with a built-in CAMAC crate and eight bismuth-germanate detectors 7.62 cm in diameter and 7.62 cm long. Gamma-ray pulse-height distributions are acquired simultaneously for up to eight positions. The system was very carefully calibrated and characterized from 0.1 to 8.3 MeV using gamma-ray spectra from a variety of radioactive sources. By fitting the pulse-height distributions from the sources with a function containing 17 parameters, we determined theoretical repsonse functions. We use these response functions to unfold the distributions to obtain flux spectra. A flux-to-dose-rate conversion curve based on the workmore » of Dimbylow and Francis is then used to obtain dose rates. Direct use of measured spectra and flux-to-dose-rate curves to obtain dose rates avoids the errors that can arise from spectrum dependence in simple gamma-ray dosimeter instruments. We present some gamma-ray doses for the Little Boy assembly operated at low power. These results can be used to determine the exposures of the Hiroshima survivors and thus aid in the establishment of radation exposure limits for the nuclear industry.« less

The He I 2.06 microns/Br-gamma ratio in starburst galaxies - An objective constraint on the upper mass limit to the initial mass function

NASA Technical Reports Server (NTRS)

Doyon, Rene; Puxley, P. J.; Joseph, R. D.

1992-01-01

The use of the He I 2.06 microns/Br-gamma ratio as a constraint on the massive stellar population in star-forming galaxies is developed. A theoretical relationship between the He I 2.06 microns/Br-gamma ratio and the effective temperature of the exciting star in H II regions is derived. The effects of collisional excitation and dust within the nebula on the ratio are also considered. It is shown that the He I 2.06 microns/Br-gamma ratio is a steep function of the effective temperature, a property which can be used to determine the upper mass limit of the initial mass function (IMF) in galaxies. This technique is reliable for upper mass limits less than about 40 solar masses. New near-infrared spectra of starburst galaxies are presented. The He I 2.06 microns/Br-gamma ratios observed imply a range of upper mass limits from 27 to over 40 solar masses. There is also evidence that the upper mass limit is spatially dependent within a given galaxy. These results suggest that the upper mass limit is not a uniquely defined parameter of the IMF and probably varies with local physical conditions.

Photon strength and the low-energy enhancement

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wiedeking, M.; Bernstein, L. A.; Bleuel, D. L.

2014-08-14

Several measurements in medium mass nuclei have reported a low-energy enhancement in the photon strength function. Although, much effort has been invested in unraveling the mysteries of this effect, its physical origin is still not conclusively understood. Here, a completely model-independent experimental approach to investigate the existence of this enhancement is presented. The experiment was designed to study statistical feeding from the quasi-continuum (below the neutron separation energy) to individual low-lying discrete levels in {sup 95}Mo produced in the (d, p) reaction. A key aspect to successfully study gamma decay from the region of high-level density is the detection andmore » extraction of correlated particle-gamma-gamma events which was accomplished using an array of Clover HPGe detectors and large area annular silicon detectors. The entrance channel excitation energy into the residual nucleus produced in the reaction was inferred from the detected proton energies in the silicon detectors. Gating on gamma-transitions originating from low-lying discrete levels specifies the state fed by statistical gamma-rays. Any particle-gamma-gamma event in combination with specific energy sum requirements ensures a clean and unambiguous determination of the initial and final state of the observed gamma rays. With these requirements the statistical feeding to individual discrete levels is extracted on an event-by-event basis. The results are presented and compared to {sup 95}Mo photon strength function data measured at the University of Oslo.« less

Selective Coupling between Theta Phase and Neocortical Fast Gamma Oscillations during REM-Sleep in Mice

PubMed Central

Scheffzük, Claudia; Kukushka, Valeriy I.; Vyssotski, Alexei L.; Draguhn, Andreas

2011-01-01

Background The mammalian brain expresses a wide range of state-dependent network oscillations which vary in frequency and spatial extension. Such rhythms can entrain multiple neurons into coherent patterns of activity, consistent with a role in behaviour, cognition and memory formation. Recent evidence suggests that locally generated fast network oscillations can be systematically aligned to long-range slow oscillations. It is likely that such cross-frequency coupling supports specific tasks including behavioural choice and working memory. Principal Findings We analyzed temporal coupling between high-frequency oscillations and EEG theta activity (4–12 Hz) in recordings from mouse parietal neocortex. Theta was exclusively present during active wakefulness and REM-sleep. Fast oscillations occurred in two separate frequency bands: gamma (40–100 Hz) and fast gamma (120–160 Hz). Theta, gamma and fast gamma were more prominent during active wakefulness as compared to REM-sleep. Coupling between theta and the two types of fast oscillations, however, was more pronounced during REM-sleep. This state-dependent cross-frequency coupling was particularly strong for theta-fast gamma interaction which increased 9-fold during REM as compared to active wakefulness. Theta-gamma coupling increased only by 1.5-fold. Significance State-dependent cross-frequency-coupling provides a new functional characteristic of REM-sleep and establishes a unique property of neocortical fast gamma oscillations. Interactions between defined patterns of slow and fast network oscillations may serve selective functions in sleep-dependent information processing. PMID:22163023

The self-absorption effect of gamma rays in /sup 239/Pu

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hsu, Hsiao-Hua

1989-01-01

Nuclear materials assay with gamma-ray spectrum measurement is a well-established method for safeguards. However, for a thick source, the self-absorption of characteristic low-energy gamma rays has been a handicap to accurate assay. I have carried out Monte Carlo simulations to study this effect using the /sup 239/Pu ..cap alpha..-decay gamma-ray spectrum as an example. The thickness of a plutonium metal source can be considered a function of gamma-ray intensity ratios. In a practical application, gamma-ray intensity ratios can be obtained from a measured spectrum. With the help of calculated curves, scientists can find the source thickness and make corrections tomore » gamma-ray intensities, which then lead to an accurate quantitative determination of radioactive isotopes in the material. 2 refs., 9 figs.« less

The neutron-gamma Feynman variance to mean approach: Gamma detection and total neutron-gamma detection (theory and practice)

NASA Astrophysics Data System (ADS)

Chernikova, Dina; Axell, Kåre; Avdic, Senada; Pázsit, Imre; Nordlund, Anders; Allard, Stefan

2015-05-01

Two versions of the neutron-gamma variance to mean (Feynman-alpha method or Feynman-Y function) formula for either gamma detection only or total neutron-gamma detection, respectively, are derived and compared in this paper. The new formulas have particular importance for detectors of either gamma photons or detectors sensitive to both neutron and gamma radiation. If applied to a plastic or liquid scintillation detector, the total neutron-gamma detection Feynman-Y expression corresponds to a situation where no discrimination is made between neutrons and gamma particles. The gamma variance to mean formulas are useful when a detector of only gamma radiation is used or when working with a combined neutron-gamma detector at high count rates. The theoretical derivation is based on the Chapman-Kolmogorov equation with the inclusion of general reactions and corresponding intensities for neutrons and gammas, but with the inclusion of prompt reactions only. A one energy group approximation is considered. The comparison of the two different theories is made by using reaction intensities obtained in MCNPX simulations with a simplified geometry for two scintillation detectors and a 252Cf-source. In addition, the variance to mean ratios, neutron, gamma and total neutron-gamma are evaluated experimentally for a weak 252Cf neutron-gamma source, a 137Cs random gamma source and a 22Na correlated gamma source. Due to the focus being on the possibility of using neutron-gamma variance to mean theories for both reactor and safeguards applications, we limited the present study to the general analytical expressions for Feynman-alpha formulas.

An improved time of flight gamma-ray telescope to monitor diffuse gamma-ray in the energy range 5 MeV - 50 MeV

NASA Technical Reports Server (NTRS)

Dacostafereiraneri, A.; Bui-Van, A.; Lavigne, J. M.; Sabaud, C.; Vedrenne, G.; Agrinier, B.; Gouiffes, C.

1985-01-01

A time of flight measuring device is the basic triggering system of most of medium and high energy gamma-ray telescopes. A simple gamma-ray telescope has been built in order to check in flight conditions the functioning of an advanced time of flight system. The technical ratings of the system are described. This telescope has been flown twice with stratospheric balloons, its axis being oriented at various Zenital directions. Flight results are presented for diffuse gamma-rays, atmospheric secondaries, and various causes of noise in the 5 MeV-50 MeV energy range.

Carbonic anhydrase III regulates peroxisome proliferator-activated receptor-{gamma}2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mitterberger, Maria C.; Kim, Geumsoo; Rostek, Ursula

2012-05-01

Carbonic anhydrase III (CAIII) is an isoenzyme of the CA family. Because of its low specific anhydrase activity, physiological functions in addition to hydrating CO{sub 2} have been proposed. CAIII expression is highly induced in adipogenesis and CAIII is the most abundant protein in adipose tissues. The function of CAIII in both preadipocytes and adipocytes is however unknown. In the present study we demonstrate that adipogenesis is greatly increased in mouse embryonic fibroblasts (MEFs) from CAIII knockout (KO) mice, as demonstrated by a greater than 10-fold increase in the induction of fatty acid-binding protein-4 (FABP4) and increased triglyceride formation inmore » CAIII{sup -/-} MEFs compared with CAIII{sup +/+} cells. To address the underlying mechanism, we investigated the expression of the two adipogenic key regulators, peroxisome proliferator-activated receptor-{gamma}2 (PPAR{gamma}2) and CCAAT/enhancer binding protein-{alpha}. We found a considerable (approximately 1000-fold) increase in the PPAR{gamma}2 expression in the CAIII{sup -/-} MEFs. Furthermore, RNAi-mediated knockdown of endogenous CAIII in NIH 3T3-L1 preadipocytes resulted in a significant increase in the induction of PPAR{gamma}2 and FABP4. When both CAIII and PPAR{gamma}2 were knocked down, FABP4 was not induced. We conclude that down-regulation of CAIII in preadipocytes enhances adipogenesis and that CAIII is a regulator of adipogenic differentiation which acts at the level of PPAR{gamma}2 gene expression. -- Highlights: Black-Right-Pointing-Pointer We discover a novel function of Carbonic anhydrase III (CAIII). Black-Right-Pointing-Pointer We show that CAIII is a regulator of adipogenesis. Black-Right-Pointing-Pointer We demonstrate that CAIII acts at the level of PPAR{gamma}2 gene expression. Black-Right-Pointing-Pointer Our data contribute to a better understanding of the role of CAIII in fat tissue.« less

Gamma Radiation (5-10 Gy) Impairs Neuronal Function in the Guinea Pig Hippocampus

DTIC Science & Technology

1993-01-01

Radiation (5-10 Gy) Impairs Neuronal Function in the Guinea Pig Hippocampus TERRY C. PELLMAR AND DENNIS L. LEPINSKI Ph.vsiology Department..Irmned Forces...L. Gamma Radiation ioral effects. Within hours of irradiation with 10 Gy and (5- 10 Gy) Impairs Neuronal Function in the Guinea Pig Hippo- less...acti v- Guinea pigs were exposed to 5 and 10 Gy ’y radiation. Hippo- ity (9) are evident. campal brain slices were isolated 30 min, I day, 3 days and 5

Development and application of a hybrid transport methodology for active interrogation systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Royston, K.; Walters, W.; Haghighat, A.

A hybrid Monte Carlo and deterministic methodology has been developed for application to active interrogation systems. The methodology consists of four steps: i) neutron flux distribution due to neutron source transport and subcritical multiplication; ii) generation of gamma source distribution from (n, 7) interactions; iii) determination of gamma current at a detector window; iv) detection of gammas by the detector. This paper discusses the theory and results of the first three steps for the case of a cargo container with a sphere of HEU in third-density water cargo. To complete the first step, a response-function formulation has been developed tomore » calculate the subcritical multiplication and neutron flux distribution. Response coefficients are pre-calculated using the MCNP5 Monte Carlo code. The second step uses the calculated neutron flux distribution and Bugle-96 (n, 7) cross sections to find the resulting gamma source distribution. In the third step the gamma source distribution is coupled with a pre-calculated adjoint function to determine the gamma current at a detector window. The AIMS (Active Interrogation for Monitoring Special-Nuclear-Materials) software has been written to output the gamma current for a source-detector assembly scanning across a cargo container using the pre-calculated values and taking significantly less time than a reference MCNP5 calculation. (authors)« less

The determination of accurate dipole polarizabilities alpha and gamma for the noble gases

NASA Technical Reports Server (NTRS)

Rice, Julia E.; Taylor, Peter R.; Lee, Timothy J.; Almlof, Jan

1991-01-01

Accurate static dipole polarizabilities alpha and gamma of the noble gases He through Xe were determined using wave functions of similar quality for each system. Good agreement with experimental data for the static polarizability gamma was obtained for Ne and Xe, but not for Ar and Kr. Calculations suggest that the experimental values for these latter ions are too low.

The perception of coherent and non-coherent auditory objects: a signature in gamma frequency band.

PubMed

Knief, A; Schulte, M; Bertran, O; Pantev, C

2000-07-01

The pertinence of gamma band activity in magnetoencephalographic and electroencephalographic recordings for the performance of a gestalt recognition process is a question at issue. We investigated the functional relevance of gamma band activity for the perception of auditory objects. An auditory experiment was performed as an analog to the Kanizsa experiment in the visual modality, comprising four different coherent and non-coherent stimuli. For the first time functional differences of evoked gamma band activity due to the perception of these stimuli were demonstrated by various methods (localization of sources, wavelet analysis and independent component analysis, ICA). Responses to coherent stimuli were found to have more features in common compared to non-coherent stimuli (e.g. closer located sources and smaller number of ICA components). The results point to the existence of a pitch processor in the auditory pathway.

Gamma Oscillations and Visual Binding

NASA Astrophysics Data System (ADS)

Robinson, Peter A.; Kim, Jong Won

2006-03-01

At the root of visual perception is the mechanism the brain uses to analyze features in a scene and bind related ones together. Experiments show this process is linked to oscillations of brain activity in the 30-100 Hz gamma band. Oscillations at different sites have correlation functions (CFs) that often peak at zero lag, implying simultaneous firing, even when conduction delays are large. CFs are strongest between cells stimulated by related features. Gamma oscillations are studied here by modeling mm-scale patchy interconnections in the visual cortex. Resulting predictions for gamma responses to stimuli account for numerous experimental findings, including why oscillations and zero-lag synchrony are associated, observed connections with feature preferences, the shape of the zero-lag peak, and variations of CFs with attention. Gamma waves are found to obey the Schroedinger equation, opening the possibility of cortical analogs of quantum phenomena. Gamma instabilities are tied to observations of gamma activity linked to seizures and hallucinations.

Revealing a steroid receptor ligand as a unique PPAR[gamma] agonist

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lin, Shengchen; Han, Ying; Shi, Yuzhe

2012-06-28

Peroxisome proliferator-activated receptor gamma (PPAR{gamma}) regulates metabolic homeostasis and is a molecular target for anti-diabetic drugs. We report here the identification of a steroid receptor ligand, RU-486, as an unexpected PPAR{gamma} agonist, thereby uncovering a novel signaling route for this steroid drug. Similar to rosiglitazone, RU-486 modulates the expression of key PPAR{gamma} target genes and promotes adipocyte differentiation, but with a lower adipogenic activity. Structural and functional studies of receptor-ligand interactions reveal the molecular basis for a unique binding mode for RU-486 in the PPAR{gamma} ligand-binding pocket with distinctive properties and epitopes, providing the molecular mechanisms for the discrimination ofmore » RU-486 from thiazolidinediones (TZDs) drugs. Our findings together indicate that steroid compounds may represent an alternative approach for designing non-TZD PPAR{gamma} ligands in the treatment of insulin resistance.« less

N1N8-bis(gamma-glutamyl)spermidine cross-linking in epidermal-cell envelopes. Comparison of cross-link levels in normal and psoriatic cell envelopes.

PubMed Central

Martinet, N; Beninati, S; Nigra, T P; Folk, J E

1990-01-01

N1N8-Bis(gamma-glutamyl)spermidine was found in exhaustive proteolytic digests of isolated cell envelopes from human epidermis at levels comparable with those of epsilon-(gamma-glutamyl)lysine. Significantly higher than normal amounts of these compounds, particularly the bis(gamma-glutamyl)polyamine, were observed in envelopes from afflicted areas (scales) of psoriatic patients. These findings support the notions that N1N8-bis(gamma-glutamyl)spermidine, like epsilon-(gamma-glutamyl)lysine, functions in cell envelopes as an enzyme-generated protein cross-link and stabilizing force and that individuals with the chronic, recurrent skin disease, psoriasis, exhibit in involved epidermis abnormal cell-envelope-protein cross-linking. PMID:2241917

Gamma-band abnormalities as markers of autism spectrum disorders

PubMed Central

Rojas, Donald C.; Wilson, Lisa B.

2014-01-01

Summary Autism is a behaviorally diagnosed neurodevelopmental disorder with no current biomarkers with high specificity and sensitivity. Gamma-band abnormalities have been reported in many studies of autism spectrum disorders. Gamma-band activity is associated with perceptual and cognitive functions that are compromised in autism. Some gamma-band deficits have also been seen in unaffected first-degree relatives, suggesting heritability of these findings. This review covers the published literature on gamma abnormalities in autism, the proposed mechanisms underlying the deficits, and the potential for translation into new treatments. Although the utility of gamma-band metrics as diagnostic biomarkers is currently limited, such changes in autism are also useful as endophenotypes, for evaluating potential neural mechanisms, and for use as surrogate markers of treatment response to interventions. PMID:24712425

Inverse Gaussian gamma distribution model for turbulence-induced fading in free-space optical communication.

PubMed

Cheng, Mingjian; Guo, Ya; Li, Jiangting; Zheng, Xiaotong; Guo, Lixin

2018-04-20

We introduce an alternative distribution to the gamma-gamma (GG) distribution, called inverse Gaussian gamma (IGG) distribution, which can efficiently describe moderate-to-strong irradiance fluctuations. The proposed stochastic model is based on a modulation process between small- and large-scale irradiance fluctuations, which are modeled by gamma and inverse Gaussian distributions, respectively. The model parameters of the IGG distribution are directly related to atmospheric parameters. The accuracy of the fit among the IGG, log-normal, and GG distributions with the experimental probability density functions in moderate-to-strong turbulence are compared, and results indicate that the newly proposed IGG model provides an excellent fit to the experimental data. As the receiving diameter is comparable with the atmospheric coherence radius, the proposed IGG model can reproduce the shape of the experimental data, whereas the GG and LN models fail to match the experimental data. The fundamental channel statistics of a free-space optical communication system are also investigated in an IGG-distributed turbulent atmosphere, and a closed-form expression for the outage probability of the system is derived with Meijer's G-function.

Flash-Bang Detector to Model the Attenuation of High-Energy Photons

NASA Astrophysics Data System (ADS)

Pagsanjan, N., III; Kelley, N. A.; Smith, D. M.; Sample, J. G.

2015-12-01

It has been known for years that lightning and thunderstorms produce gamma rays and x-rays. Terrestrial gamma-ray flashes (TGFs) are extremely bright bursts of gamma rays originating from thunderstorms. X-ray stepped leaders are bursts of x-rays coming from the lightning channel. It is known that the attenuation of these high-energy photons is a function of distance, losing energy and intensity at larger distances. To complement gamma-ray detectors on the ground it would be useful to measure the distance to the flash. Knowing the distance would allow for the true source fluence of gamma rays or x-rays to be modeled. A flash-bang detector, which uses a micro-controller, a photodiode, a microphone and temperature sensor will be able to detect the times at which lightning and thunder occurs. Knowing the speed of sound as function of temperature and the time difference between the flash and the thunder, the range to the lightning can be calculated. We will present the design of our detector as well as some preliminary laboratory test results.

Relationship between the mechanisms of gamma rhythm generation and the magnitude of the macroscopic phase response function in a population of excitatory and inhibitory modified quadratic integrate-and-fire neurons

NASA Astrophysics Data System (ADS)

Akao, Akihiko; Ogawa, Yutaro; Jimbo, Yasuhiko; Ermentrout, G. Bard; Kotani, Kiyoshi

2018-01-01

Gamma oscillations are thought to play an important role in brain function. Interneuron gamma (ING) and pyramidal interneuron gamma (PING) mechanisms have been proposed as generation mechanisms for these oscillations. However, the relation between the generation mechanisms and the dynamical properties of the gamma oscillation are still unclear. Among the dynamical properties of the gamma oscillation, the phase response function (PRF) is important because it encodes the response of the oscillation to inputs. Recently, the PRF for an inhibitory population of modified theta neurons that generate an ING rhythm was computed by the adjoint method applied to the associated Fokker-Planck equation (FPE) for the model. The modified theta model incorporates conductance-based synapses as well as the voltage and current dynamics. Here, we extended this previous work by creating an excitatory-inhibitory (E-I) network using the modified theta model and described the population dynamics with the corresponding FPE. We conducted a bifurcation analysis of the FPE to find parameter regions which generate gamma oscillations. In order to label the oscillatory parameter regions by their generation mechanisms, we defined ING- and PING-type gamma oscillation in a mathematically plausible way based on the driver of the inhibitory population. We labeled the oscillatory parameter regions by these generation mechanisms and derived PRFs via the adjoint method on the FPE in order to investigate the differences in the responses of each type of oscillation to inputs. PRFs for PING and ING mechanisms are derived and compared. We found the amplitude of the PRF for the excitatory population is larger in the PING case than in the ING case. Finally, the E-I population of the modified theta neuron enabled us to analyze the PRFs of PING-type gamma oscillation and the entrainment ability of E and I populations. We found a parameter region in which PRFs of E and I are both purely positive in the case of PING oscillations. The different entrainment abilities of E and I stimulation as governed by the respective PRFs was compared to direct simulations of finite populations of model neurons. We find that it is easier to entrain the gamma rhythm by stimulating the inhibitory population than by stimulating the excitatory population as has been found experimentally.

Bisensory stimulation increases gamma-responses over multiple cortical regions.

PubMed

Sakowitz, O W; Quiroga, R Q; Schürmann, M; Başar, E

2001-04-01

In the framework of the discussion about gamma (approx. 40 Hz) oscillations as information carriers in the brain, we investigated the relationship between gamma responses in the EEG and intersensory association. Auditory evoked potentials (AEPs) and visual evoked potentials (VEPs) were compared with bisensory evoked potentials (BEPs; simultaneous auditory and visual stimulation) in 15 subjects. Gamma responses in AEPs, VEPs and BEPs were assessed by means of wavelet decomposition. Overall maximum gamma-components post-stimulus were highest in BEPs (P < 0.01). Bisensory evoked gamma-responses also showed significant central, parietal and occipital amplitude-increases (P < 0.001, P < 0.01, P < 0.05, respectively; prestimulus interval as baseline). These were of greater magnitude when compared with the unisensory responses. As a correlate of the marked gamma responses to bimodal stimulation we suggest a process of 'intersensory association', i.e. one of the steps between sensory transmission and perception. Our data may be interpreted as a further example of function-related gamma responses in the EEG.

Strong potential wave functions with elastic channel distortion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Macek, J.; Taulbjerg, K.

1989-06-01

The strong-potential Born approximation is analyzed in a channel-distorted-wave approach. Channel-distorted SPB wave functions are reduced to a conventional form in which the standard off-energy-shell factor /ital g/ has been replaced by a modified factor ..gamma.., which represents a suitable average of /ital g/ over the momentum distribution of the distorted-channel function. The modified factor is evaluated in a physically realistic model for the distortion potential, and it is found that ..gamma.. is well represented by a slowly varying phase factor. The channel-distorted SPB approximation is accordingly identical to the impulse approximation if the phase variation of ..gamma.. can bemore » ignored. This is generally the case in applications to radiative electron capture and to a good approximation for ordinary capture at not too small velocities.« less

Neutron Diffraction Study On Gamma To Alpha Phase Transition In Ce0.9th0.1 Alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lashley, Jason C1; Heffner, Robert H; Llobet, A

2008-01-01

Comprehensive neutron diffraction measurements were performed to study the isostructural {gamma} {leftrightarrow} {alpha} phase transition in Ce{sub 0.9}Th{sub 0.1} alloy. Using Rietveld refinements, we obtained lattice and thermal parameters as a function of temperature. From the temperature slope of the thermal parameters, we determined Debye temperatures {Theta}{sup {gamma}}{sub D} = 133(1) K and {Theta}{sup {alpha}}{sub D} = 140(1) K for the {gamma} phase and the {alpha} phase, respectively. This result implies that the vibrational entropy change is not significant at the {gamma} {leftrightarrow} {alpha} transition, contrary to that from elemental Cerium [Phys. Rev. Lett. 92, 105702, 2004].

gamma-Glutamyl amino acids. Transport and conversion to 5-oxoproline in the kidney

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bridges, R.J.; Meister, A.

1985-06-25

Transport of gamma-glutamyl amino acids, a step in the proposed glutathione-gamma-glutamyl transpeptidase-mediated amino acid transport pathway, was examined in mouse kidney. The transport of gamma-glutamyl amino acids was demonstrated in vitro in studies on kidney slices. Transport was followed by measuring uptake of /sup 35/S after incubation of the slices in media containing gamma-glutamyl methionine (/sup 35/S)sulfone. The experimental complication associated with extracellular conversion of the gamma-glutamyl amino acid to amino acid and uptake of the latter by slices was overcome by using 5-oxoproline formation (catalyzed by intracellular gamma-glutamyl-cyclotransferase) as an indicator of gamma-glutamyl amino acid transport. This method wasmore » also successfully applied to studies on transport of gamma-glutamyl amino acids in vivo. Transport of gamma-glutamyl amino acids in vitro and in vivo is inhibited by several inhibitors of gamma-glutamyl transpeptidase and also by high extracellular levels of glutathione. This seems to explain urinary excretion of gamma-glutamylcystine by humans with gamma-glutamyl transpeptidase deficiency and by mice treated with inhibitors of this enzyme. Mice depleted of glutathione by treatment with buthionine sulfoximine (which inhibits glutathione synthesis) or by treatment with 2,6-dimethyl-2,5-heptadiene-4-one (which effectively interacts with tissue glutathione) exhibited significantly less transport of gamma-glutamyl amino acids than did untreated controls. The findings suggest that intracellular glutathione functions in transport of gamma-glutamyl amino acids. Evidence was also obtained for transport of gamma-glutamyl gamma-glutamylphenylalanine into kidney slices.« less

Hippocampal theta, gamma, and theta-gamma coupling: effects of aging, environmental change, and cholinergic activation

PubMed Central

Jacobson, Tara K.; Howe, Matthew D.; Schmidt, Brandy; Hinman, James R.; Escabí, Monty A.

2013-01-01

Hippocampal theta and gamma oscillations coordinate the timing of multiple inputs to hippocampal neurons and have been linked to information processing and the dynamics of encoding and retrieval. One major influence on hippocampal rhythmicity is from cholinergic afferents. In both humans and rodents, aging is linked to impairments in hippocampus-dependent function along with degradation of cholinergic function. Cholinomimetics can reverse some age-related memory impairments and modulate oscillations in the hippocampus. Therefore, one would expect corresponding changes in these oscillations and possible rescue with the cholinomimetic physostigmine. Hippocampal activity was recorded while animals explored a familiar or a novel maze configuration. Reexposure to a familiar situation resulted in minimal aging effects or changes in theta or gamma oscillations. In contrast, exploration of a novel maze configuration increased theta power; this was greater in adult than old animals, although the deficit was reversed with physostigmine. In contrast to the theta results, the effects of novelty, age, and/or physostigmine on gamma were relatively weak. Unrelated to the behavioral situation were an age-related decrease in the degree of theta-gamma coupling and the fact that physostigmine lowered the frequency of theta in both adult and old animals. The results indicate that age-related changes in gamma and theta modulation of gamma, while reflecting aging changes in hippocampal circuitry, seem less related to aging changes in information processing. In contrast, the data support a role for theta and the cholinergic system in encoding and that hippocampal aging is related to impaired encoding of new information. PMID:23303862

Differences in MEG gamma oscillatory power during performance of a prosaccade task in adolescents with FASD

PubMed Central

Stephen, Julia M.; Coffman, Brian A.; Stone, David B.; Kodituwakku, Piyadasa

2013-01-01

Fetal alcohol spectrum disorder (FASD) is characterized by a broad range of behavioral and cognitive deficits that impact the long-term quality of life for affected individuals. However, the underlying changes in brain structure and function associated with these cognitive impairments are not well-understood. Previous studies identified deficits in behavioral performance of prosaccade tasks in children with FASD. In this study, we investigated group differences in gamma oscillations during performance of a prosaccade task. We collected magnetoencephalography (MEG) data from 15 adolescents with FASD and 20 age-matched healthy controls (HC) with a mean age of 15.9 ± 0.4 years during performance of a prosaccade task. Eye movement was recorded and synchronized to the MEG data using an MEG compatible eye-tracker. The MEG data were analyzed relative to the onset of the visual saccade. Time-frequency analysis was performed using Fieldtrip with a focus on group differences in gamma-band oscillations. Following left target presentation, we identified four clusters over right frontal, right parietal, and left temporal/occipital cortex, with significantly different gamma-band (30–50 Hz) power between FASD and HC. Furthermore, visual M100 latencies described in Coffman etal. (2012) corresponded with increased gamma power over right central cortex in FASD only. Gamma-band differences were not identified for stimulus-averaged responses implying that these gamma-band differences were related to differences in saccade network functioning. These differences in gamma-band power may provide indications of atypical development of cortical networks in individuals with FASD. PMID:24399957

Bidirectional modulation of hippocampal gamma (20-80 Hz) frequency activity in vitro via alpha(α)- and beta(β)-adrenergic receptors (AR).

PubMed

Haggerty, D C; Glykos, V; Adams, N E; Lebeau, F E N

2013-12-03

Noradrenaline (NA) in the hippocampus plays an important role in memory function and has been shown to modulate different forms of synaptic plasticity. Oscillations in the gamma frequency (20-80 Hz) band in the hippocampus have also been proposed to play an important role in memory functions and, evidence from both in vitro and in vivo studies, has suggested this activity can be modulated by NA. However, the role of different NA receptor subtypes in the modulation of gamma frequency activity has not been fully elucidated. We have found that NA (30 μM) exerts a bidirectional control on the magnitude of kainate-evoked (50-200 nM) gamma frequency oscillations in the cornu Ammonis (CA3) region of the rat hippocampus in vitro via activation of different receptor subtypes. Activation of alpha-adrenergic receptors (α-AR) reduced the power of the gamma frequency oscillation. In contrast, activation of beta-adrenergic receptors (β-AR) caused an increase in the power of the gamma frequency oscillations. Using specific agonists and antagonists of AR receptor subtypes we demonstrated that these effects are mediated specifically via α1A-AR and β1-AR subtypes. NA activated both receptor subtypes, but the α1A-AR-mediated effect predominated, resulting in a reversible suppression of gamma frequency activity. These results suggest that NA is able to differentially modulate on-going gamma frequency oscillatory activity that could result in either increased or decreased information flow through the hippocampus. Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

Antagonist of peroxisome proliferator-activated receptor {gamma} induces cerebellar amyloid-{beta} levels and motor dysfunction in APP/PS1 transgenic mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Du, Jing; Sun, Bing; Chen, Kui

2009-07-03

Recent evidences show that peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}) is involved in the modulation of the amyloid-{beta} (A{beta}) cascade causing Alzheimer's disease (AD) and treatment with PPAR{gamma} agonists protects against AD pathology. However, the function of PPAR{gamma} steady-state activity in A{beta} cascade and AD pathology remains unclear. In this study, an antagonist of PPAR{gamma}, GW9662, was injected into the fourth ventricle of APP/PS1 transgenic mice to inhibit PPAR{gamma} activity in cerebellum. The results show that inhibition of PPAR{gamma} significantly induced A{beta} levels in cerebellum and caused cerebellar motor dysfunction in APP/PS1 transgenic mice. Moreover, GW9662 treatment markedly decreased the cerebellarmore » levels of insulin-degrading enzyme (IDE), which is responsible for the cellular degradation of A{beta}. Since cerebellum is spared from significant A{beta} accumulation and neurotoxicity in AD patients and animal models, these findings suggest a crucial role of PPAR{gamma} steady-state activity in protection of cerebellum against AD pathology.« less

Frequency-dependent oscillatory neural profiles during imitation.

PubMed

Sugata, Hisato; Hirata, Masayuki; Tamura, Yuichi; Onishi, Hisao; Goto, Tetsu; Araki, Toshihiko; Yorifuji, Shiro

2017-04-10

Imitation is a complex process that includes higher-order cognitive and motor function. This process requires an observation-execution matching system that transforms an observed action into an identical movement. Although the low-gamma band is thought to reflect higher cognitive processes, no studies have focused on it. Here, we used magnetoencephalography (MEG) to examine the neural oscillatory changes including the low-gamma band during imitation. Twelve healthy, right-handed participants performed a finger task consisting of four conditions (imitation, execution, observation, and rest). During the imitation and execution conditions, significant event-related desynchronizations (ERDs) were observed at the left frontal, central, and parietal MEG sensors in the alpha, beta, and low-gamma bands. Functional connectivity analysis at the sensor level revealed an imitation-related connectivity between a group of frontal sensors and a group of parietal sensors in the low-gamma band. Furthermore, source reconstruction with synthetic aperture magnetometry showed significant ERDs in the low-gamma band in the left sensorimotor area and the middle frontal gyrus (MFG) during the imitation condition when compared with the other three conditions. Our results suggest that the oscillatory neural activities of the low-gamma band at the sensorimotor area and MFG play an important role in the observation-execution matching system related to imitation.

Searches for correlation between UHECR events and high-energy gamma-ray Fermi-LAT data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Álvarez, Ezequiel; Cuoco, Alessandro; Mirabal, Nestor

The astrophysical sources responsible for ultra high-energy cosmic rays (UHECRs) continue to be one of the most intriguing mysteries in astrophysics. We present a comprehensive search for correlations between high-energy (∼> 1 GeV) gamma-ray events from the Fermi Large Area Telescope (LAT) and UHECRs (∼> 60 EeV) detected by the Telescope Array and the Pierre Auger Observatory. We perform two separate searches. First, we conduct a standard cross-correlation analysis between the arrival directions of 148 UHECRs and 360 gamma-ray sources in the Second Catalog of Hard Fermi-LAT sources (2FHL). Second, we search for a possible correlation between UHECR directions andmore » unresolved Fermi -LAT gamma-ray emission. For the latter, we use three different methods: a stacking technique with both a model-dependent and model-independent background estimate, and a cross-correlation function analysis. We also test for statistically significant excesses in gamma rays from signal regions centered on Cen A and the Telescope Array hotspot. No significant correlation is found in any of the analyses performed, except a weak (∼< 2σ) hint of signal with the correlation function method on scales ∼ 1°. Upper limits on the flux of possible power-law gamma-ray sources of UHECRs are derived.« less

Searches for correlation between UHECR events and high-energy gamma-ray Fermi-LAT data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Álvarez, Ezequiel; Cuoco, Alessandro; Mirabal, Nestor

The astrophysical sources responsible for ultra high-energy cosmic rays (UHECRs) continue to be one of the most intriguing mysteries in astrophysics. Here, we present a comprehensive search for correlations between high-energy (≳ 1 GeV) gamma-ray events from the Fermi Large Area Telescope (LAT) and UHECRs (≳ 60 EeV) detected by the Telescope Array and the Pierre Auger Observatory. We perform two separate searches. First, we conduct a standard cross-correlation analysis between the arrival directions of 148 UHECRs and 360 gamma-ray sources in the Second Catalog of Hard Fermi-LAT sources (2FHL). Second, we search for a possible correlation between UHECR directionsmore » and unresolved Fermi-LAT gamma-ray emission. For the latter, we use three different methods: a stacking technique with both a model-dependent and model-independent background estimate, and a cross-correlation function analysis. We also test for statistically significant excesses in gamma rays from signal regions centered on Cen A and the Telescope Array hotspot. There was no significant correlation is found in any of the analyses performed, except a weak (≲ 2σ) hint of signal with the correlation function method on scales ~ 1°. Upper limits on the flux of possible power-law gamma-ray sources of UHECRs are derived.« less

Searches for correlation between UHECR events and high-energy gamma-ray Fermi-LAT data

DOE PAGES

Álvarez, Ezequiel; Cuoco, Alessandro; Mirabal, Nestor; ...

2016-12-13

The astrophysical sources responsible for ultra high-energy cosmic rays (UHECRs) continue to be one of the most intriguing mysteries in astrophysics. Here, we present a comprehensive search for correlations between high-energy (≳ 1 GeV) gamma-ray events from the Fermi Large Area Telescope (LAT) and UHECRs (≳ 60 EeV) detected by the Telescope Array and the Pierre Auger Observatory. We perform two separate searches. First, we conduct a standard cross-correlation analysis between the arrival directions of 148 UHECRs and 360 gamma-ray sources in the Second Catalog of Hard Fermi-LAT sources (2FHL). Second, we search for a possible correlation between UHECR directionsmore » and unresolved Fermi-LAT gamma-ray emission. For the latter, we use three different methods: a stacking technique with both a model-dependent and model-independent background estimate, and a cross-correlation function analysis. We also test for statistically significant excesses in gamma rays from signal regions centered on Cen A and the Telescope Array hotspot. There was no significant correlation is found in any of the analyses performed, except a weak (≲ 2σ) hint of signal with the correlation function method on scales ~ 1°. Upper limits on the flux of possible power-law gamma-ray sources of UHECRs are derived.« less

Frequency-dependent oscillatory neural profiles during imitation

PubMed Central

Sugata, Hisato; Hirata, Masayuki; Tamura, Yuichi; Onishi, Hisao; Goto, Tetsu; Araki, Toshihiko; Yorifuji, Shiro

2017-01-01

Imitation is a complex process that includes higher-order cognitive and motor function. This process requires an observation-execution matching system that transforms an observed action into an identical movement. Although the low-gamma band is thought to reflect higher cognitive processes, no studies have focused on it. Here, we used magnetoencephalography (MEG) to examine the neural oscillatory changes including the low-gamma band during imitation. Twelve healthy, right-handed participants performed a finger task consisting of four conditions (imitation, execution, observation, and rest). During the imitation and execution conditions, significant event-related desynchronizations (ERDs) were observed at the left frontal, central, and parietal MEG sensors in the alpha, beta, and low-gamma bands. Functional connectivity analysis at the sensor level revealed an imitation-related connectivity between a group of frontal sensors and a group of parietal sensors in the low-gamma band. Furthermore, source reconstruction with synthetic aperture magnetometry showed significant ERDs in the low-gamma band in the left sensorimotor area and the middle frontal gyrus (MFG) during the imitation condition when compared with the other three conditions. Our results suggest that the oscillatory neural activities of the low-gamma band at the sensorimotor area and MFG play an important role in the observation-execution matching system related to imitation. PMID:28393878

Abnormal functional connectivity of EEG gamma band in patients with depression during emotional face processing.

PubMed

Li, Yingjie; Cao, Dan; Wei, Ling; Tang, Yingying; Wang, Jijun

2015-11-01

This paper evaluates the large-scale structure of functional brain networks using graph theoretical concepts and investigates the difference in brain functional networks between patients with depression and healthy controls while they were processing emotional stimuli. Electroencephalography (EEG) activities were recorded from 16 patients with depression and 14 healthy controls when they performed a spatial search task for facial expressions. Correlations between all possible pairs of 59 electrodes were determined by coherence, and the coherence matrices were calculated in delta, theta, alpha, beta, and gamma bands (low gamma: 30-50Hz and high gamma: 50-80Hz, respectively). Graph theoretical analysis was applied to these matrices by using two indexes: the clustering coefficient and the characteristic path length. The global EEG coherence of patients with depression was significantly higher than that of healthy controls in both gamma bands, especially in the high gamma band. The global coherence in both gamma bands from healthy controls appeared higher in negative conditions than in positive conditions. All the brain networks were found to hold a regular and ordered topology during emotion processing. However, the brain network of patients with depression appeared randomized compared with the normal one. The abnormal network topology of patients with depression was detected in both the prefrontal and occipital regions. The negative bias from healthy controls occurred in both gamma bands during emotion processing, while it disappeared in patients with depression. The proposed work studied abnormally increased connectivity of brain functional networks in patients with depression. By combing the clustering coefficient and the characteristic path length, we found that the brain networks of patients with depression and healthy controls had regular networks during emotion processing. Yet the brain networks of the depressed group presented randomization trends. Moreover, negative bias was detected in the healthy controls during emotion processing, while it was not detected in patients with depression, which might be related to the types of negative stimuli used in this study. The brain networks from both patients with depression and healthy controls were found to hold a regular and ordered topology. Yet the brain networks of patients with depression had randomization trends. Copyright © 2015 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Three- and four-dimensional mapping of speech and language in patients with epilepsy.

PubMed

Nakai, Yasuo; Jeong, Jeong-Won; Brown, Erik C; Rothermel, Robert; Kojima, Katsuaki; Kambara, Toshimune; Shah, Aashit; Mittal, Sandeep; Sood, Sandeep; Asano, Eishi

2017-05-01

We have provided 3-D and 4D mapping of speech and language function based upon the results of direct cortical stimulation and event-related modulation of electrocorticography signals. Patients estimated to have right-hemispheric language dominance were excluded. Thus, 100 patients who underwent two-stage epilepsy surgery with chronic electrocorticography recording were studied. An older group consisted of 84 patients at least 10 years of age (7367 artefact-free non-epileptic electrodes), whereas a younger group included 16 children younger than age 10 (1438 electrodes). The probability of symptoms transiently induced by electrical stimulation was delineated on a 3D average surface image. The electrocorticography amplitude changes of high-gamma (70-110 Hz) and beta (15-30 Hz) activities during an auditory-naming task were animated on the average surface image in a 4D manner. Thereby, high-gamma augmentation and beta attenuation were treated as summary measures of cortical activation. Stimulation data indicated the causal relationship between (i) superior-temporal gyrus of either hemisphere and auditory hallucination; (ii) left superior-/middle-temporal gyri and receptive aphasia; (iii) widespread temporal/frontal lobe regions of the left hemisphere and expressive aphasia; and (iv) bilateral precentral/left posterior superior-frontal regions and speech arrest. On electrocorticography analysis, high-gamma augmentation involved the bilateral superior-temporal and precentral gyri immediately following question onset; at the same time, high-gamma activity was attenuated in the left orbitofrontal gyrus. High-gamma activity was augmented in the left temporal/frontal lobe regions, as well as left inferior-parietal and cingulate regions, maximally around question offset, with high-gamma augmentation in the left pars orbitalis inferior-frontal, middle-frontal, and inferior-parietal regions preceded by high-gamma attenuation in the contralateral homotopic regions. Immediately before verbal response, high-gamma augmentation involved the posterior superior-frontal and pre/postcentral regions, bilaterally. Beta-attenuation was spatially and temporally correlated with high-gamma augmentation in general but with exceptions. The younger and older groups shared similar spatial-temporal profiles of high-gamma and beta modulation; except, the younger group failed to show left-dominant activation in the rostral middle-frontal and pars orbitalis inferior-frontal regions around stimulus offset. The human brain may rapidly and alternately activate and deactivate cortical areas advantageous or obtrusive to function directed toward speech and language at a given moment. Increased left-dominant activation in the anterior frontal structures in the older age group may reflect developmental consolidation of the language system. The results of our functional mapping may be useful in predicting, across not only space but also time and patient age, sites specific to language function for presurgical evaluation of focal epilepsy. © The Author (2017). Published by Oxford University Press on behalf of the Guarantors of Brain.

Three- and four-dimensional mapping of speech and language in patients with epilepsy

PubMed Central

Nakai, Yasuo; Jeong, Jeong-won; Brown, Erik C.; Rothermel, Robert; Kojima, Katsuaki; Kambara, Toshimune; Shah, Aashit; Mittal, Sandeep; Sood, Sandeep

2017-01-01

We have provided 3-D and 4D mapping of speech and language function based upon the results of direct cortical stimulation and event-related modulation of electrocorticography signals. Patients estimated to have right-hemispheric language dominance were excluded. Thus, 100 patients who underwent two-stage epilepsy surgery with chronic electrocorticography recording were studied. An older group consisted of 84 patients at least 10 years of age (7367 artefact-free non-epileptic electrodes), whereas a younger group included 16 children younger than age 10 (1438 electrodes). The probability of symptoms transiently induced by electrical stimulation was delineated on a 3D average surface image. The electrocorticography amplitude changes of high-gamma (70–110 Hz) and beta (15–30 Hz) activities during an auditory-naming task were animated on the average surface image in a 4D manner. Thereby, high-gamma augmentation and beta attenuation were treated as summary measures of cortical activation. Stimulation data indicated the causal relationship between (i) superior-temporal gyrus of either hemisphere and auditory hallucination; (ii) left superior-/middle-temporal gyri and receptive aphasia; (iii) widespread temporal/frontal lobe regions of the left hemisphere and expressive aphasia; and (iv) bilateral precentral/left posterior superior-frontal regions and speech arrest. On electrocorticography analysis, high-gamma augmentation involved the bilateral superior-temporal and precentral gyri immediately following question onset; at the same time, high-gamma activity was attenuated in the left orbitofrontal gyrus. High-gamma activity was augmented in the left temporal/frontal lobe regions, as well as left inferior-parietal and cingulate regions, maximally around question offset, with high-gamma augmentation in the left pars orbitalis inferior-frontal, middle-frontal, and inferior-parietal regions preceded by high-gamma attenuation in the contralateral homotopic regions. Immediately before verbal response, high-gamma augmentation involved the posterior superior-frontal and pre/postcentral regions, bilaterally. Beta-attenuation was spatially and temporally correlated with high-gamma augmentation in general but with exceptions. The younger and older groups shared similar spatial-temporal profiles of high-gamma and beta modulation; except, the younger group failed to show left-dominant activation in the rostral middle-frontal and pars orbitalis inferior-frontal regions around stimulus offset. The human brain may rapidly and alternately activate and deactivate cortical areas advantageous or obtrusive to function directed toward speech and language at a given moment. Increased left-dominant activation in the anterior frontal structures in the older age group may reflect developmental consolidation of the language system. The results of our functional mapping may be useful in predicting, across not only space but also time and patient age, sites specific to language function for presurgical evaluation of focal epilepsy. PMID:28334963

High resolution mapping of the binding site on human IgG1 for Fc gamma RI, Fc gamma RII, Fc gamma RIII, and FcRn and design of IgG1 variants with improved binding to the Fc gamma R.

PubMed

Shields, R L; Namenuk, A K; Hong, K; Meng, Y G; Rae, J; Briggs, J; Xie, D; Lai, J; Stadlen, A; Li, B; Fox, J A; Presta, L G

2001-03-02

Immunoglobulin G (IgG) Fc receptors play a critical role in linking IgG antibody-mediated immune responses with cellular effector functions. A high resolution map of the binding site on human IgG1 for human Fc gamma RI, Fc gamma RIIA, Fc gamma RIIB, Fc gamma RIIIA, and FcRn receptors has been determined. A common set of IgG1 residues is involved in binding to all Fc gamma R; Fc gamma RII and Fc gamma RIII also utilize residues outside this common set. In addition to residues which, when altered, abrogated binding to one or more of the receptors, several residues were found that improved binding only to specific receptors or simultaneously improved binding to one type of receptor and reduced binding to another type. Select IgG1 variants with improved binding to Fc gamma RIIIA exhibited up to 100% enhancement in antibody-dependent cell cytotoxicity using human effector cells; these variants included changes at residues not found at the binding interface in the IgG/Fc gamma RIIIA co-crystal structure (Sondermann, P., Huber, R., Oosthuizen, V., and Jacob, U. (2000) Nature 406, 267-273). These engineered antibodies may have important implications for improving antibody therapeutic efficacy.

Alpha-crystallins are involved in specific interactions with the murine gamma D/E/F-crystallin-encoding gene.

PubMed

Pietrowski, D; Durante, M J; Liebstein, A; Schmitt-John, T; Werner, T; Graw, J

1994-07-08

The promoter of the murine gamma E-crystallin (gamma E-Cry) encoding gene (gamma E-cry) was analyzed for specific interactions with lenticular proteins in a gel-retardation assay. A 21-bp fragment immediately downstream of the transcription initiation site (DOTIS) is demonstrated to be responsible for specific interactions with lens extracts. The DOTIS-binding protein(s) accept only the sense DNA strand as target; anti-sense or double-stranded DNA do not interact with these proteins. The DOTIS sequence element is highly conserved among the murine gamma D-, gamma E- and gamma F-cry and is present at comparable positions in the orthologous rat genes. Only a weak or even no protein-binding activity is observed if a few particular bases are changed, as in the rat gamma A-, gamma C- and gamma E-cry elements. DOTIS-binding proteins were found in commercially available bovine alpha-Cry preparations. The essential participation of alpha-Cry in the DNA-binding protein complex was confirmed using alpha-Cry-specific monoclonal antibody. The results reported here point to a novel function of alpha-Cry besides the structural properties in the lens.

The Nucleus Reuniens Controls Long-Range Hippocampo-Prefrontal Gamma Synchronization during Slow Oscillations.

PubMed

Ferraris, Maëva; Ghestem, Antoine; Vicente, Ana F; Nallet-Khosrofian, Lauriane; Bernard, Christophe; Quilichini, Pascale P

2018-03-21

Gamma oscillations are involved in long-range coupling of distant regions that support various cognitive operations. Here we show in adult male rats that synchronized bursts of gamma oscillations bind the hippocampus (HPC) and prefrontal cortex (mPFC) during slow oscillations and slow-wave sleep, a brain state that is central for consolidation of memory traces. These gamma bursts entrained the firing of the local HPC and mPFC neuronal populations. Neurons of the nucleus reuniens (NR), which is a structural and functional hub between HPC and mPFC, demonstrated a specific increase in their firing before gamma burst onset, suggesting their involvement in HPC-mPFC binding. Chemical inactivation of NR disrupted the temporal pattern of gamma bursts and their synchronization, as well as mPFC neuronal firing. We propose that the NR drives long-range hippocampo-prefrontal coupling via gamma bursts providing temporal windows for information exchange between the HPC and mPFC during slow-wave sleep. SIGNIFICANCE STATEMENT Long-range coupling between hippocampus (HPC) and prefrontal cortex (mPFC) is believed to support numerous cognitive functions, including memory consolidation occurring during sleep. Gamma-band synchronization is a fundamental process in many neuronal operations and is instrumental in long-range coupling. Recent evidence highlights the role of nucleus reuniens (NR) in consolidation; however, how it influences hippocampo-prefrontal coupling is unknown. In this study, we show that HPC and mPFC are synchronized by gamma bursts during slow oscillations in anesthesia and natural sleep. By manipulating and recording the NR-HPC-mPFC network, we provide evidence that the NR actively promotes this long-range gamma coupling. This coupling provides the hippocampo-prefrontal circuit with a novel mechanism to exchange information during slow-wave sleep. Copyright © 2018 the authors 0270-6474/18/383026-13$15.00/0.

Lactoferrin-Immobilized Surfaces onto Functionalized PLA Assisted by the Gamma-Rays and Nitrogen Plasma to Create Materials with Multifunctional Properties.

PubMed

Stoleru, Elena; Zaharescu, Traian; Hitruc, Elena Gabriela; Vesel, Alenka; Ioanid, Emil G; Coroaba, Adina; Safrany, Agnes; Pricope, Gina; Lungu, Maria; Schick, Christoph; Vasile, Cornelia

2016-11-23

Both cold nitrogen radiofrequency plasma and gamma irradiation have been applied to activate and functionalize the polylactic acid (PLA) surface and the subsequent lactoferrin immobilization. Modified films were comparatively characterized with respect to the procedure of activation and also with unmodified sample by water contact angle measurements, mass loss, X-ray photoelectron spectroscopy (XPS), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), atomic force microscopy (AFM), and chemiluminescence measurements. All modified samples exhibit enhanced surface properties mainly those concerning biocompatibility, antimicrobial, and antioxidant properties, and furthermore, they are biodegradable and environmentally friendly. Lactoferrin deposited layer by covalent coupling using carbodiimide chemistry showed a good stability. It was found that the lactoferrin-modified PLA materials present significantly increased oxidative stability. Gamma-irradiated samples and lactoferrin-functionalized samples show higher antioxidant, antimicrobial, and cell proliferation activity than plasma-activated and lactoferrin-functionalized ones. The multifunctional materials thus obtained could find application as biomaterials or as bioactive packaging films.

Durability Assessment of Various Gamma TiAl Alloys

NASA Technical Reports Server (NTRS)

Lerch, Brad; Draper, Sue; Pereira, Mike; Zhuang, Wyman

2003-01-01

Seven cast and one wrought gamma-alloys were ballistically impacted and tested under high cycle fatigue. The fatigue strength of each alloy was characterized as a function of initial flaw size and modeled using a threshold-based fracture mechanics approach.

Standard model light-by-light scattering in SANC: Analytic and numeric evaluation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bardin, D. Yu., E-mail: bardin@nu.jinr.ru; Kalinovskaya, L. V., E-mail: kalinov@nu.jinr.ru; Uglov, E. D., E-mail: corner@nu.jinr.r

2010-11-15

The implementation of the Standard Model process {gamma}{gamma} {yields} {gamma}{gamma} through a fermion and boson loop into the framework of SANC system and additional precomputation modules used for calculation of massive box diagrams are described. The computation of this process takes into account nonzero mass of loop particles. The covariant and helicity amplitudes for this process, some particular cases of D{sub 0} and C{sub 0} Passarino-Veltman functions, and also numerical results of corresponding SANC module evaluation are presented. Whenever possible, the results are compared with those existing in the literature.

Phenotypic screening of hepatocyte nuclear factor (HNF) 4-{gamma} receptor knockout mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gerdin, Anna Karin; Surve, Vikas V.; Joensson, Marie

2006-10-20

Using the mouse as a model organism in pharmaceutical research presents unique advantages as its physiology in many ways resembles the human physiology, it also has a relatively short generation time, low breeding and maintenance costs, and is available in a wide variety of inbred strains. The ability to genetically modify mouse embryonic stem cells to generate mouse models that better mimic human disease is another advantage. In the present study, a comprehensive phenotypic screening protocol is applied to elucidate the phenotype of a novel mouse knockout model of hepatocyte nuclear factor (HNF) 4-{gamma}. HNF4-{gamma} is expressed in the kidneys,more » gut, pancreas, and testis. First level of the screen is aimed at general health, morphologic appearance, normal cage behaviour, and gross neurological functions. The second level of the screen looks at metabolic characteristics and lung function. The third level of the screen investigates behaviour more in-depth and the fourth level consists of a thorough pathological characterisation, blood chemistry, haematology, and bone marrow analysis. When compared with littermate wild-type mice (HNF4-{gamma}{sup +/+}), the HNF4-{gamma} knockout (HNF4-{gamma}{sup -/-}) mice had lowered energy expenditure and locomotor activity during night time that resulted in a higher body weight despite having reduced intake of food and water. HNF4-{gamma}{sup -/-} mice were less inclined to build nest and were found to spend more time in a passive state during the forced swim test.« less

A novel phoswich imaging detector for simultaneous beta and coincidence-gamma imaging of plant leaves.

PubMed

Wu, Heyu; Tai, Yuan-Chuan

2011-09-07

To meet the growing demand for functional imaging technology for use in studying plant biology, we are developing a novel technique that permits simultaneous imaging of escaped positrons and coincidence gammas from annihilation of positrons within an intake leaf. The multi-modality imaging system will include two planar detectors: one is a typical PET detector array and the other is a phoswich imaging detector that detects both beta and gamma. The novel phoswich detector is made of a plastic scintillator, a lutetium oxyorthosilicate (LSO) array, and a position sensitive photomultiplier tube (PS-PMT). The plastic scintillator serves as a beta detector, while the LSO array serves as a gamma detector and light guide that couples scintillation light from the plastic detector to the PMT. In our prototype, the PMT signal was fed into the Siemens QuickSilver electronics to achieve shaping and waveform sampling. Pulse-shape discrimination based on the detectors' decay times (2.1 ns for plastic and 40 ns for LSO) was used to differentiate beta and gamma events using the common PMT signals. Using our prototype phoswich detector, we simultaneously measured a beta image and gamma events (in single mode). The beta image showed a resolution of 1.6 mm full-width-at-half-maximum using F-18 line sources. Because this shows promise for plant-scale imaging, our future plans include development of a fully functional simultaneous beta-and-coincidence-gamma imager with sub-millimeter resolution imaging capability for both modalities.

LFlGRB: Luminosity function of long gamma-ray bursts

NASA Astrophysics Data System (ADS)

Paul, Debdutta

2018-04-01

LFlGRB models the luminosity function (LF) of long Gamma Ray Bursts (lGRBs) by using a sample of Swift and Fermi lGRBs to re-derive the parameters of the Yonetoku correlation and self-consistently estimate pseudo-redshifts of all the bursts with unknown redshifts. The GRB formation rate is modeled as the product of the cosmic star formation rate and a GRB formation efficiency for a given stellar mass.

Assessment of right ventricular function with nonimaging first pass ventriculography and comparison of results with gamma camera studies.

PubMed

Zhang, Z; Liu, X J; Liu, Y Z; Lu, P; Crawley, J C; Lahiri, A

1990-08-01

A new technique has been developed for measuring right ventricular function by nonimaging first pass ventriculography. The right ventricular ejection fraction (RVEF) obtained by non-imaging first pass ventriculography was compared with that obtained by gamma camera first pass and equilibrium ventriculography. The data has demonstrated that the correlation of RVEFs obtained by the nonimaging nuclear cardiac probe and by gamma camera first pass ventriculography in 15 subjects was comparable (r = 0.93). There was also a good correlation between RVEFs obtained by the nonimaging nuclear probe and by equilibrium gated blood pool studies in 33 subjects (r = 0.89). RVEF was significantly reduced in 15 patients with right ventricular and/or inferior myocardial infarction compared to normal subjects (28 +/- 9% v. 45 +/- 9%). The data suggests that nonimaging probes may be used for assessing right ventricular function accurately.

The Differential Interactions of Peroxisome Proliferator-Activated Receptor [gamma] Ligands with Tyr473 Is a Physical Basis for Their Unique Biological Activities

DOE Office of Scientific and Technical Information (OSTI.GOV)

Einstein, Monica; Akiyama, Taro E.; Castriota, Gino A.

2008-08-01

Despite their proven antidiabetic efficacy, widespread use of peroxisome proliferator-activated receptor (PPAR){gamma} agonists has been limited by adverse cardiovascular effects. To overcome this shortcoming, selective PPAR{gamma} modulators (SPPAR{gamma}Ms) have been identified that have antidiabetic efficacy comparable with full agonists with improved tolerability in preclinical species. The results of structural studies support the proposition that SPPAR{gamma}Ms interact with PPAR{gamma} differently from full agonists, thereby providing a physical basis for their novel activities. Herein, we describe a novel PPAR{gamma} ligand, SPPAR{gamma}M2. This compound was a partial agonist in a cell-based transcriptional activity assay, with diminished adipogenic activity and an attenuated gene signaturemore » in cultured human adipocytes. X-ray cocrystallography studies demonstrated that, unlike rosiglitazone, SPPAR{gamma}M2 did not interact with the Tyr473 residue located within helix 12 of the ligand binding domain (LBD). Instead, SPPAR{gamma}M2 was found to bind to and activate human PPAR{gamma} in which the Tyr473 residue had been mutated to alanine (hPPAR{gamma}Y473A), with potencies similar to those observed with the wild-type receptor (hPPAR{gamma}WT). In additional studies, we found that the intrinsic binding and functional potencies of structurally distinct SPPAR{gamma}Ms were not diminished by the Y473A mutation, whereas those of various thiazolidinedione (TZD) and non-TZD PPAR{gamma} full agonists were reduced in a correlative manner. These results directly demonstrate the important role of Tyr473 in mediating the interaction of full agonists but not SPPAR{gamma}Ms with the PPAR{gamma} LBD, thereby providing a precise molecular determinant for their differing pharmacologies.« less

GAMSOR: Gamma Source Preparation and DIF3D Flux Solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, M. A.; Lee, C. H.; Hill, R. N.

2016-12-15

Nuclear reactors that rely upon the fission reaction have two modes of thermal energy deposition in the reactor system: neutron absorption and gamma absorption. The gamma rays are typically generated by neutron absorption reactions or during the fission process which means the primary driver of energy production is of course the neutron interaction. In conventional reactor physics methods, the gamma heating component is ignored such that the gamma absorption is forced to occur at the gamma emission site. For experimental reactor systems like EBR-II and FFTF, the placement of structural pins and assemblies internal to the core leads to problemsmore » with power heating predictions because there is no fission power source internal to the assembly to dictate a spatial distribution of the power. As part of the EBR-II support work in the 1980s, the GAMSOR code was developed to assist analysts in calculating the gamma heating. The GAMSOR code is a modified version of DIF3D and actually functions within a sequence of DIF3D calculations. The gamma flux in a conventional fission reactor system does not perturb the neutron flux and thus the gamma flux calculation can be cast as a fixed source problem given a solution to the steady state neutron flux equation. This leads to a sequence of DIF3D calculations, called the GAMSOR sequence, which involves solving the neutron flux, then the gamma flux, then combining the results to do a summary edit. In this manuscript, we go over the GAMSOR code and detail how it is put together and functions. We also discuss how to setup the GAMSOR sequence and input for each DIF3D calculation in the GAMSOR sequence. With the GAMSOR capability, users can take any valid steady state DIF3D calculation and compute the power distribution due to neutron and gamma heating. The MC2-3 code is the preferable companion code to use for generating neutron and gamma cross section data, but the GAMSOR code can accept cross section data from other sources. To further this aspect, an additional utility code was created which demonstrates how to merge the neutron and gamma cross section data together to carry out a simultaneous solve of the two systems.« less

Growth, structural, optical and thermal properties of gamma-glycine crystal.

PubMed

Balakrishnan, T; Babu, R Ramesh; Ramamurthi, K

2008-04-01

Single crystals of gamma-glycine were grown from a mixture of glycine, water and lithium bromide. Single crystal X-ray diffraction analysis confirmed the growth of gamma-glycine phase. Presence of various functional groups of gamma-glycine was identified by FTIR spectrum. Optical absorbance spectrum recorded in the wavelength range of UV-vis-NIR revealed that this crystal has good optical transparency in the range 250-1500 nm. Vickers microhardness values were estimated on the prominent (100) face. Thermogravimetric and differential scanning calorimetric analyses were carried out to study the thermal properties of gamma-glycine. Second harmonic generation efficiency of the crystal measured by Kurtz's powder method using Nd:YAG laser is about three times that of KDP.

Wavelet-based techniques for the gamma-ray sky

DOE Office of Scientific and Technical Information (OSTI.GOV)

McDermott, Samuel D.; Fox, Patrick J.; Cholis, Ilias

2016-07-01

Here, we demonstrate how the image analysis technique of wavelet decomposition can be applied to the gamma-ray sky to separate emission on different angular scales. New structures on scales that differ from the scales of the conventional astrophysical foreground and background uncertainties can be robustly extracted, allowing a model-independent characterization with no presumption of exact signal morphology. As a test case, we generate mock gamma-ray data to demonstrate our ability to extract extended signals without assuming a fixed spatial template. For some point source luminosity functions, our technique also allows us to differentiate a diffuse signal in gamma-rays from darkmore » matter annihilation and extended gamma-ray point source populations in a data-driven way.« less

Olfactory system gamma oscillations: the physiological dissection of a cognitive neural system

PubMed Central

Rojas-Líbano, Daniel

2008-01-01

Oscillatory phenomena have been a focus of dynamical systems research since the time of the classical studies on the pendulum by Galileo. Fast cortical oscillations also have a long and storied history in neurophysiology, and olfactory oscillations have led the way with a depth of explanation not present in the literature of most other cortical systems. From the earliest studies of odor-evoked oscillations by Adrian, many reports have focused on mechanisms and functional associations of these oscillations, in particular for the so-called gamma oscillations. As a result, much information is now available regarding the biophysical mechanisms that underlie the oscillations in the mammalian olfactory system. Recent studies have expanded on these and addressed functionality directly in mammals and in the analogous insect system. Sub-bands within the rodent gamma oscillatory band associated with specific behavioral and cognitive states have also been identified. All this makes oscillatory neuronal networks a unique interdisciplinary platform from which to study neurocognitive and dynamical phenomena in intact, freely behaving animals. We present here a summary of what has been learned about the functional role and mechanisms of gamma oscillations in the olfactory system as a guide for similar studies in other cortical systems. PMID:19003484

Reduced gamma-aminobutyric acid concentration is associated with physical disability in progressive multiple sclerosis

PubMed Central

Solanky, Bhavana S.; Muhlert, Nils; Tur, Carmen; Edden, Richard A. E.; Wheeler-Kingshott, Claudia A. M.; Miller, David H.; Thompson, Alan J.; Ciccarelli, Olga

2015-01-01

Neurodegeneration is thought to be the major cause of ongoing, irreversible disability in progressive stages of multiple sclerosis. Gamma-aminobutyric acid is the principle inhibitory neurotransmitter in the brain. The aims of this study were to investigate if gamma-aminobutyric acid levels (i) are abnormal in patients with secondary progressive multiple sclerosis compared with healthy controls; and (ii) correlate with physical and cognitive performance in this patient population. Thirty patients with secondary progressive multiple sclerosis and 17 healthy control subjects underwent single-voxel MEGA-PRESS (MEscher-GArwood Point RESolved Spectroscopy) magnetic resonance spectroscopy at 3 T, to quantify gamma-aminobutyric acid levels in the prefrontal cortex, right hippocampus and left sensorimotor cortex. All subjects were assessed clinically and underwent a cognitive assessment. Multiple linear regression models were used to compare differences in gamma-aminobutyric acid concentrations between patients and controls adjusting for age, gender and tissue fractions within each spectroscopic voxel. Regression was used to examine the relationships between the cognitive function and physical disability scores specific for these regions with gamma-aminobuytric acid levels, adjusting for age, gender, and total N-acetyl-aspartate and glutamine-glutamate complex levels. When compared with controls, patients performed significantly worse on all motor and sensory tests, and were cognitively impaired in processing speed and verbal memory. Patients had significantly lower gamma-aminobutyric acid levels in the hippocampus (adjusted difference = −0.403 mM, 95% confidence intervals −0.792, −0.014, P = 0.043) and sensorimotor cortex (adjusted difference = −0.385 mM, 95% confidence intervals −0.667, −0.104, P = 0.009) compared with controls. In patients, reduced motor function in the right upper and lower limb was associated with lower gamma-aminobutyric acid concentration in the sensorimotor cortex. Specifically for each unit decrease in gamma-aminobutyric acid levels (in mM), there was a predicted −10.86 (95% confidence intervals −16.786 to −4.482) decrease in grip strength (kg force) (P < 0.001) and −8.74 (95% confidence intervals −13.943 to −3.015) decrease in muscle strength (P < 0.006). This study suggests that reduced gamma-aminobutyric acid levels reflect pathological abnormalities that may play a role in determining physical disability. These abnormalities may include decreases in the pre- and postsynaptic components of gamma-aminobutyric acid neurotransmission and in the density of inhibitory neurons. Additionally, the reduced gamma-aminobutyric acid concentration may contribute to the neurodegenerative process, resulting in increased firing of axons, with consequent increased energy demands, which may lead to neuroaxonal degeneration and loss of the compensatory mechanisms that maintain motor function. This study supports the idea that modulation of gamma-aminobutyric acid neurotransmission may be an important target for neuroprotection in multiple sclerosis. See De Stefano and Giorgio (doi:10.1093/brain/awv213) for a scientific commentary on this article. PMID:26304151

Probability density of aperture-averaged irradiance fluctuations for long range free space optical communication links.

PubMed

Lyke, Stephen D; Voelz, David G; Roggemann, Michael C

2009-11-20

The probability density function (PDF) of aperture-averaged irradiance fluctuations is calculated from wave-optics simulations of a laser after propagating through atmospheric turbulence to investigate the evolution of the distribution as the aperture diameter is increased. The simulation data distribution is compared to theoretical gamma-gamma and lognormal PDF models under a variety of scintillation regimes from weak to strong. Results show that under weak scintillation conditions both the gamma-gamma and lognormal PDF models provide a good fit to the simulation data for all aperture sizes studied. Our results indicate that in moderate scintillation the gamma-gamma PDF provides a better fit to the simulation data than the lognormal PDF for all aperture sizes studied. In the strong scintillation regime, the simulation data distribution is gamma gamma for aperture sizes much smaller than the coherence radius rho0 and lognormal for aperture sizes on the order of rho0 and larger. Examples of how these results affect the bit-error rate of an on-off keyed free space optical communication link are presented.

GLAST and Ground-Based Gamma-Ray Astronomy

NASA Technical Reports Server (NTRS)

McEnery, Julie

2008-01-01

The launch of the Gamma-ray Large Area Space Telescope together with the advent of a new generation of ground-based gamma-ray detectors such as VERITAS, HESS, MAGIC and CANGAROO, will usher in a new era of high-energy gamma-ray astrophysics. GLAST and the ground based gamma-ray observatories will provide highly complementary capabilities for spectral, temporal and spatial studies of high energy gamma-ray sources. Joint observations will cover a huge energy range, from 20 MeV to over 20 TeV. The LAT will survey the entire sky every three hours, allowing it both to perform uniform, long-term monitoring of variable sources and to detect flaring sources promptly. Both functions complement the high-sensitivity pointed observations provided by ground-based detectors. Finally, the large field of view of GLAST will allow a study of gamma-ray emission on large angular scales and identify interesting regions of the sky for deeper studies at higher energies. In this poster, we will discuss the science returns that might result from joint GLAST/ground-based gamma-ray observations and illustrate them with detailed source simulations.

Detecting the Attenuation of Blazar Gamma-ray Emission by Extragalactic Background Light with GLAST

NASA Technical Reports Server (NTRS)

Chen, Andrew; Ritz, Steven

1999-01-01

Gamma rays with energy above 10 GeV interact with optical-UV photons resulting in pair production. Therefore, a large sample of high redshift sources of these gamma rays can be used to probe the extragalactic background starlight (EBL) by examining the redshift dependence of the attenuation of the flux above 10 GeV. GLAST, the next generation high-energy gamma-ray telescope, will for the first time have the unique capability to detect thousands of gamma-ray blazars up to redshifts of at least z = 4, with enough angular resolution to allow identification of a large fraction of their optical counterparts. By combining recent determinations of the gamma-ray blazar luminosity function, recent calculations of the high energy gamma-ray opacity due to EBL absorption, and the expected GLAST instrument performance to produce simulated samples of blazars that GLAST would detect, including their redshifts and fluxes, we demonstrate that these blazars have the potential to be a highly effective probe of the EBL.

A Monte Carlo Simulation of Prompt Gamma Emission from Fission Fragments

NASA Astrophysics Data System (ADS)

Regnier, D.; Litaize, O.; Serot, O.

2013-03-01

The prompt fission gamma spectra and multiplicities are investigated through the Monte Carlo code FIFRELIN which is developed at the Cadarache CEA research center. Knowing the fully accelerated fragment properties, their de-excitation is simulated through a cascade of neutron, gamma and/or electron emissions. This paper presents the recent developments in the FIFRELIN code and the results obtained on the spontaneous fission of 252Cf. Concerning the decay cascades simulation, a fully Hauser-Feshbach model is compared with a previous one using a Weisskopf spectrum for neutron emission. A particular attention is paid to the treatment of the neutron/gamma competition. Calculations lead using different level density and gamma strength function models show significant discrepancies of the slope of the gamma spectra at high energy. The underestimation of the prompt gamma spectra obtained regardless our de-excitation cascade modeling choice is discussed. This discrepancy is probably linked to an underestimation of the post-neutron fragments spin in our calculation.

Regulation of gamma-Secretase in Alzheimer's Disease

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Shuxia; Zhou, Hua; Walian, Peter

2007-02-07

The {gamma}-secretase complex is an intramembrane aspartyl protease that cleaves its substrates along their transmembrane regions. Sequential proteolytic processing of amyloid precursor protein by {beta}- and {gamma}-secretase produces amyloid {beta}-peptides, which are the major components of amyloid plaques in the brains of Alzheimer's disease patients. The {gamma}-secretase complex is therefore believed to be critical in the pathogenesis of Alzheimer's disease. Here we review the range of factors found to affect the nature and degree of {gamma}-secretase complex activity; these include {gamma}-secretase complex assembly and activation, the integral regulatory subunit CD147, transient or weak binding partners, the levels of cholesterol andmore » sphingolipids in cell membranes, and inflammatory cytokines. Integrated knowledge of the molecular mechanisms supporting the actions of these factors is expected to lead to a comprehensive understanding of the functional regulation of the {gamma}-secretase complex, and this, in turn, should facilitate the development of novel therapeutic strategies for the treatment of Alzheimer's disease.« less

Delayed growth of EL4 lymphoma in SR-A-deficient mice is due to upregulation of nitric oxide and interferon-gamma production by tumor-associated macrophages.

PubMed

Komohara, Yoshihiro; Takemura, Kenichi; Lei, Xiao Feng; Sakashita, Naomi; Harada, Mamoru; Suzuki, Hiroshi; Kodama, Tatsuhiko; Takeya, Motohiro

2009-11-01

Class A scavenger receptors (SR-A, CD204) are highly expressed in tumor-associated macrophages (TAM). To investigate the function of SR-A in TAM, wild-type and SR-A-deficient (SR-A(-/-)) mice were injected with EL4 cells. Although these groups of mice did not differ in the numbers of infiltrating macrophages and lymphocytes and in neovascularization, SR-A(-/-) mice had delayed growth of EL4 tumors. Expression of inducible nitric oxide (NO) synthase and interferon (IFN)-gamma mRNA increased significantly in tumor tissues from SR-A(-/-) mice. Engulfment of necrotic EL4 cells induced upregulation of NO and IFN-gamma production by cultured macrophages, and production of NO and IFN-gamma increased in SR-A(-/-) macrophages in vitro. IFN-beta production by cultured macrophages was also elevated in SR-A(-/-) macrophages in vitro. These results suggested that the antitumor activity of macrophages increased in SR-A(-/-) mice because of upregulation of NO and IFN-gamma production. These data indicate an important role of SR-A in regulating TAM function by inhibiting toll-like receptor (TLR)4-IFN-beta signaling.

Genomic sequences of murine gamma B- and gamma C-crystallin-encoding genes: promoter analysis and complete evolutionary pattern of mouse, rat and human gamma-crystallins.

PubMed

Graw, J; Liebstein, A; Pietrowski, D; Schmitt-John, T; Werner, T

1993-12-22

The murine genes, gamma B-cry and gamma C-cry, encoding the gamma B- and gamma C-crystallins, were isolated from a genomic DNA library. The complete nucleotide (nt) sequences of both genes were determined from 661 and 711 bp, respectively, upstream from the first exon to the corresponding polyadenylation sites, comprising more than 2650 and 2890 bp, respectively. The new sequences were compared to the partial cDNA sequences available for the murine gamma B-cry and gamma C-cry, as well as to the corresponding genomic sequences from rat and man, at both the nt and predicted amino acid (aa) sequence levels. In the gamma B-cry promoter region, a canonical CCAAT-box, a TATA-box, putative NF-I and C/EBP sites were detected. An R-repeat is inserted 366 bp upstream from the transcription start point. In contrast, the gamma C-cry promoter does not contain a CCAAT-box, but some other putative binding sites for transcription factors (AP-2, UBP-1, LBP-1) were located by computer analysis. The promoter regions of all six gamma-cry from mouse, rat and human, except human psi gamma F-cry, were analyzed for common sequence elements. A complex sequence element of about 70-80 bp was found in the proximal promoter, which contains a gamma-cry-specific and almost invariant sequence (crygpel) of 14 nt, and ends with the also invariant TATA-box. Within the complex sequence element, a minimum of three further features specific for the gamma A-, gamma B- and gamma D/E/F-cry genes can be defined, at least two of which were recently shown to be functional. In addition to these four sequence elements, a subtype-specific structure of inverted repeats with different-sized spacers can be deduced from the multiple sequence alignment. A phylogenetic analysis based on the promoter region, as well as the complete exon 3 of all gamma-cry from mouse, rat and man, suggests separation of only five gamma-cry subtypes (gamma A-, gamma B-, gamma C-, gamma D- and gamma E/F-cry) prior to species separation.

IL-4 inhibits the synthesis of IFN-gamma and induces the synthesis of IgE in human mixed lymphocyte cultures.

PubMed

Vercelli, D; Jabara, H H; Lauener, R P; Geha, R S

1990-01-15

The T cell-derived lymphokine IL-4 is essential for the induction of IgE synthesis by human lymphocytes. The IgE-inducing effect of IL-4 is antagonized by IFN-gamma. The secretion of IFN-gamma is vigorously triggered in MLC. Thus, IL-4-stimulated MLC represent a suitable model to characterize the functional antagonism between IL-4 and IFN-gamma. In this report, we show that rIL-4 consistently induced IgE synthesis when added to human primary MLC. IL-4-dependent IgE production required cognate T/B cell recognition, because it was inhibited by antibodies to CD3 and MHC class II (HlA-DR) Ag. A neutralizing anti-IFN-gamma mAb dramatically enhanced IL-4-dependent IgE synthesis by MLC, indicating that endogenous IFN-gamma is a major inhibitor of IgE production. More importantly, addition of rIL-4 markedly inhibited the release of IFN-gamma in supernatants of MLC and Con A-activated PBMC. The decrease in IFN-gamma protein was accompanied by a decreased expression of IFN-gamma mRNA transcripts. The downregulation of IFN-gamma by IL-4 is likely to play an important role in the IL-4-dependent induction of IgE synthesis.

Impaired theta-gamma coupling during working memory performance in schizophrenia.

PubMed

Barr, Mera S; Rajji, Tarek K; Zomorrodi, Reza; Radhu, Natasha; George, Tony P; Blumberger, Daniel M; Daskalakis, Zafiris J

2017-11-01

Working memory deficits represent a core feature of schizophrenia. These deficits have been associated with dysfunctional dorsolateral prefrontal cortex (DLPFC) cortical oscillations. Theta-gamma coupling describes the modulation of gamma oscillations by theta phasic activity that has been directly associated with the ordering of information during working memory performance. Evaluating theta-gamma coupling may provide greater insight into the neural mechanisms mediating working memory deficits in this disorder. Thirty-eight patients diagnosed with schizophrenia or schizoaffective disorder and 38 healthy controls performed the verbal N-Back task administered at 4 levels, while EEG was recorded. Theta (4-7Hz)-gamma (30-50Hz) coupling was calculated for target and non-target correct trials for each working memory load. The relationship between theta-gamma coupling and accuracy was determined. Theta-gamma coupling was significantly and selectively impaired during correct responses to target letters among schizophrenia patients compared to healthy controls. A significant and positive relationship was found between theta-gamma coupling and 3-Back accuracy in controls, while this relationship was not observed in patients. These findings suggest that impaired theta-gamma coupling contribute to working memory dysfunction in schizophrenia. Future work is needed to evaluate the predictive utility of theta-gamma coupling as a neurophysiological marker for functional outcomes in this disorder. Copyright © 2017. Published by Elsevier B.V.

EEG Driven tDCS Versus Bifrontal tDCS for Tinnitus

PubMed Central

De Ridder, Dirk; Vanneste, Sven

2012-01-01

Tinnitus is the perception of a sound in the absence of any objective physical sound source. Transcranial Direct Current Stimulation (tDCS) induces shifts in membrane resting potentials depending on the polarity of the stimulation: under the anode gamma band activity increases, whereas under the cathode the opposite occurs. Both single and multiple sessions of tDCS over the dorsolateral prefrontal cortex (DLPFC; anode over right DLPFC) yield a transient improvement in tinnitus intensity and tinnitus distress. The question arises whether optimization of the tDCS protocol can be obtained by using EEG driven decisions on where to place anode and cathode. Using gamma band functional connectivity could be superior to gamma band activity as functional connectivity determines the tinnitus network in many aspects of chronic tinnitus. Six-hundred-seventy-five patients were included in the study: 265 patients received tDCS with cathodal electrode placed over the left DLPFC and the anode placed overlying the right DLPFC, 380 patients received tDCS based on EEG connectivity, and 65 received no tDCS (i.e., waiting list control group). Repeated measures ANOVA revealed a significant main effect for pre versus post measurement. Bifrontal tDCS in comparison to EEG driven tDCS had a larger reduction for both tinnitus distress and tinnitus intensity. Whereas the results of the bifrontal tDCS seem to confirm previous studies, the use of gamma band functional connectivity seems not to bring any advantage to tDCS for tinnitus suppression. Using other potential biomarkers, such as gamma band activity, or theta functional connectivity could theoretically be of use. Further studies will have to elucidate whether brain state based tDCS has any advantages over “blind” bifrontal stimulation. PMID:23055986

Absence of Fc epsilonRI alpha chain results in upregulation of Fc gammaRIII-dependent mast cell degranulation and anaphylaxis. Evidence of competition between Fc epsilonRI and Fc gammaRIII for limiting amounts of FcR beta and gamma chains.

PubMed Central

Dombrowicz, D; Flamand, V; Miyajima, I; Ravetch, J V; Galli, S J; Kinet, J P

1997-01-01

In mouse mast cells, both Fc epsilonRI and Fc gammaRIII are alpha beta gamma2 tetrameric complexes in which different alpha chains confer IgE or IgG ligand recognition while the signaling FcR beta and gamma chains are identical. We used primarily noninvasive techniques (changes in body temperature, dye extravasation) to assess systemic anaphylactic responses in nonanesthetized wild-type, Fc epsilonRI alpha chain -/- and FcR gamma chain -/- mice. We confirm that systemic anaphylaxis in mice can be mediated largely through IgG1 and Fc gammaRIII and we provide direct evidence that these responses reflect activation of Fc gammaRIII rather than Fc gammaRI. Furthermore, we show that Fc gammaRIII-dependent responses are more intense in normal than in congenic mast cell-deficient KitW/KitW-v mice, indicating that Fc gammaRIII responses have mast cell-dependent and -independent components. Finally, we demonstrate that the upregulation of cell surface expression of Fc gammaRIII seen in Fc epsilonRI alpha chain -/- mice corresponds to an increased association of Fc gammaRIII alpha chains with FcR beta and gamma chains and is associated with enhanced Fc gammaRIII-dependent mast cell degranulation and systemic anaphylactic responses. Therefore, the phenotype of the Fc epsilonRI alpha chain -/- mice suggests that expression of Fc epsilonRI and Fc gammaRIII is limited by availability of the FcR beta and gamma chains and that, in normal mice, changes in the expression of one receptor (Fc epsilonRI) may influence the expression of functional responses dependent on the other (Fc gammaRIII). PMID:9062349

Streptococcus thermophilus APC151 Strain Is Suitable for the Manufacture of Naturally GABA-Enriched Bioactive Yogurt.

PubMed

Linares, Daniel M; O'Callaghan, Tom F; O'Connor, Paula M; Ross, R P; Stanton, Catherine

2016-01-01

Consumer interest in health-promoting food products is a major driving force for the increasing global demand of functional (probiotic) dairy foods. Yogurt is considered the ideal medium for delivery of beneficial functional ingredients. Gamma-amino-butyric acid has potential as a bioactive ingredient in functional foods due to its health-promoting properties as an anti-stress, anti-hypertensive, and anti-diabetic agent. Here, we report the use of a novel Streptococcus thermophilus strain, isolated from the digestive tract of fish, for production of yogurt naturally enriched with 2 mg/ml of gamma-amino-butyric acid (200 mg in a standard yogurt volume of 100 ml), a dose in the same range as that provided by some commercially available gamma-amino-butyric acid supplements. The biotechnological suitability of this strain for industrial production of yogurt was demonstrated by comparison with the reference yogurt inoculated with the commercial CH1 starter (Chr. Hansen) widely used in the dairy industry. Both yogurts showed comparable pH curves [ΔpH/Δ t = 0.31-0.33 h -1 ], viscosity [0.49 Pa-s], water holding capacity [72-73%], and chemical composition [moisture (87-88%), protein (5.05-5.65%), fat (0.12-0.15%), sugar (4.8-5.8%), and ash (0.74-1.2%)]. Gamma-amino-butyric acid was not detected in the control yogurt. In conclusion, the S. thermophilus APC151 strain reported here provides a natural means for fortification of yogurt with gamma-amino-butyric acid.

Extensions to the integral line-beam method for gamma-ray skyshine analyses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shultis, J.K.; Faw, R.E.

1995-08-01

A computationally simple method for estimating gamma-ray skyshine dose rates has been developed on the basis of the line-beam response function. Both Monte Carlo and pointkernel calculations that account for both annihilation and bremsstrahlung were used in the generation of line beam response functions (LBRF) for gamma-ray energies between 10 and 100 MeV. The LBRF is approximated by a three-parameter formula. By combining results with those obtained in an earlier study for gamma energies below 10 MeV, LBRF values are readily and accurately evaluated for source energies between 0.02 and 100 MeV, for source-to-detector distances between 1 and 3000 m,more » and beam angles as great as 180 degrees. Tables of the parameters for the approximate LBRF are presented. The new response functions are then applied to three simple skyshine geometries, an open silo geometry, an infinite wall, and a rectangular four-wall building. Results are compared to those of previous calculations and to benchmark measurements. A new approach is introduced to account for overhead shielding of the skyshine source and compared to the simplistic exponential-attenuation method used in earlier studies. The effect of the air-ground interface, usually neglected in gamma skyshine studies, is also examined and an empirical correction factor is introduced. Finally, a revised code based on the improved LBRF approximations and the treatment of the overhead shielding is presented, and results shown for several benchmark problems.« less

Self-induced intracerebral gamma oscillations in the human cortex.

PubMed

Corlier, Juliana; Rimsky-Robert, Daphné; Valderrama, Mario; Lehongre, Katia; Adam, Claude; Clémenceau, Stéphane; Charpier, Stéphane; Bastin, Julien; Kahane, Philippe; Lachaux, Jean-Philippe; Navarro, Vincent; Le Van Quyen, Michel

2016-12-01

Gamma oscillations play a pivotal role in multiple cognitive functions. They enable coordinated activity and communication of local assemblies, while abnormalities in gamma oscillations exist in different neurological and psychiatric diseases. Thus, a specific rectification of gamma synchronization could potentially compensate the deficits in pathological conditions. Previous experiments have shown that animals can voluntarily modulate their gamma power through operant conditioning. Using a closed-loop experimental setup, we show in six intracerebrally recorded epileptic patients undergoing presurgical evaluation that intracerebral power spectrum can be increased in the gamma frequency range (30-80 Hz) at different fronto-temporal cortical sites in human subjects. Successful gamma training was accompanied by increased gamma power at other cortical locations and progressively enhanced cross-frequency coupling between gamma and slow oscillations (3-12 Hz). Finally, using microelectrode targets in two subjects, we report that upregulation of gamma activities is possible also in spatial micro-domains, without the spread to macroelectrodes. Overall, our findings indicate that intracerebral gamma modulation can be achieved rapidly, beyond the motor system and with high spatial specificity, when using micro targets. These results are especially significant because they pave the way for use of high-resolution therapeutic approaches for future clinical applications. © The Author (2016). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

In-Flight Calibration of the Energetic Gamma-Ray Experiment Telescope (EGRET) on the Compton Gamma-Ray Observatory

NASA Technical Reports Server (NTRS)

Esposito, J. A.; Bertsch, D. L.; Chen, A. W.; Dingus, B. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Lin, Y. C.;

Phenomenological characteristic of the electron component in gamma-quanta initiated showers

NASA Technical Reports Server (NTRS)

Nikolsky, S. I.; Stamenov, J. N.; Ushev, S. Z.

1985-01-01

The phenomenological characteristics of the electron component in showers initiated by primary gamma-quanta were analyzed on the basis of the Tien Shan experimental data. It is shown that the lateral distribution of the electrons ion gamma-quanta initiated showers can be described with NKG - function with age parameters bar S equals 0, 76 plus or minus 0, 02, different from the same parameter for normal showers with the same size bar S equals 0, 85 plus or minus 0, 01. The lateral distribution of the correspondent electron energy flux in gamma-quanta initiated showers is steeper as in normal cosmic ray showers.

Common gamma chain cytokines: dissidence in the details.

PubMed

Alves, Nuno L; Arosa, Fernando A; van Lier, René A W

2007-02-15

Cytokines of the common cytokine-receptor gamma-chain (gamma(c)) family are essential for the development and maintenance of lymphocytes. Herein, we will focus on the roles of interleukin-2 (IL-2), IL-7, IL-15 and IL-21, in the orchestration of CD8 T cell responses. Among these cytokines, IL-7 has emerged as a master regulator of survival of immature and mature T lymphocytes, while IL-2, IL-15 and IL-21 appear to have specific functions in T cell homeostasis and differentiation. Hence, the gamma(c) has evolved as an elegant anchor through which related cytokines regulate distinct biological responses in T cells.

In situ calibration of a high-resolution gamma-ray borehole sonde for assaying uranium-bearing sandstone deposits

USGS Publications Warehouse

Day, J.H.

1985-01-01

A method is presented for assaying radioactive sandstone deposits in situ by using a high-resolution borehole gamma-ray spectrometer. Gamma-ray photopeaks from the same spectrum acquired to analyze a sample are used to characterize gamma-ray attenuation properties, from which a calibration function is determined. Assay results are independent of differences between properties of field samples and those of laboratory or test-hole standards generally used to calibrate a borehole sonde. This assaying technique is also independent of the state of radioactive disequilibrium that usually exists in nature among members of the natural-decay chains. ?? 1985.

Measurement of the 238U neutron-capture cross section and gamma-emission spectra from 10 eV to 100 keV using the DANCE detector at LANSCE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ullmann, John L; Couture, A J; Keksis, A L

2010-01-01

A careful new measurement of the {sup 238}U(n,{gamma}) cross section from 10 eV to 100 keV has been made using the DANCE detector at LANSCE. DANCE is a 4{pi} calorimetric scintillator array consisting of 160 BaF{sub 2} crystals. Measurements were made on a 48 mg/cm{sup 2} depleted uranium target. The cross sections are in general good agreement with previous measurements. The gamma-ray emission spectra, as a function of gamma multiplicity, were also measured and compared to model calculations.

Sex Differences in Gamma Band Functional Connectivity Between the Frontal Lobe and Cortical Areas During an Auditory Oddball Task, as Revealed by Imaginary Coherence Assessment.

PubMed

Fujimoto, Toshiro; Okumura, Eiichi; Kodabashi, Atsushi; Takeuchi, Kouzou; Otsubo, Toshiaki; Nakamura, Katsumi; Yatsushiro, Kazutaka; Sekine, Masaki; Kamiya, Shinichiro; Shimooki, Susumu; Tamura, Toshiyo

2016-01-01

We studied sex-related differences in gamma oscillation during an auditory oddball task, using magnetoencephalography and electroencephalography assessment of imaginary coherence (IC). We obtained a statistical source map of event-related desynchronization (ERD) / event-related synchronization (ERS), and compared females and males regarding ERD / ERS. Based on the results, we chose respectively seed regions for IC determinations in low (30-50 Hz), mid (50-100 Hz) and high gamma (100-150 Hz) bands. In males, ERD was increased in the left posterior cingulate cortex (CGp) at 500 ms in the low gamma band, and in the right caudal anterior cingulate cortex (cACC) at 125 ms in the mid-gamma band. ERS was increased in the left rostral anterior cingulate cortex (rACC) at 375 ms in the high gamma band. We chose the CGp, cACC and rACC as seeds, and examined IC between the seed and certain target regions using the IC map. IC changes depended on the height of the gamma frequency and the time window in the gamma band. Although IC in the mid and high gamma bands did not show sex-specific differences, IC at 30-50 Hz in males was increased between the left rACC and the frontal, orbitofrontal, inferior temporal and fusiform target regions. Increased IC in males suggested that males may acomplish the task constructively, analysingly, emotionally, and by perfoming analysis, and that information processing was more complicated in the cortico-cortical circuit. On the other hand, females showed few differences in IC. Females planned the task with general attention and economical well-balanced processing, which was explained by the higher overall functional cortical connectivity. CGp, cACC and rACC were involved in sex differences in information processing and were likely related to differences in neuroanatomy, hormones and neurotransmitter systems.

Inhibition of cystathionine-gamma-lyase leads to loss of glutathione and aggravation of mitochondrial dysfunction mediated by excitatory amino acid in the CNS.

PubMed

Diwakar, Latha; Ravindranath, Vijayalakshmi

2007-01-01

Oxidative stress has been implicated in the pathogenesis and progression of neurodegenerative disorders and antioxidants potentially have a major role in neuroprotection. Optimum levels of glutathione (gamma-glutamylcysteinyl glycine), an endogenous thiol antioxidant are required for the maintenance of the redox status of cells. Cystathionine gamma-lyase is the rate-limiting enzyme for the synthesis of cysteine from methionine and availability of cysteine is a critical factor in glutathione synthesis. In the present study, we have examined the role of cystathionine gamma-lyase in maintaining the redox homeostasis in brain, particularly with reference to mitochondrial function since the complex I of the electron transport chain is sensitive to redox perturbation. Inhibition of cystathionine gamma-lyase by l-propargylglycine caused loss of glutathione and decrease in complex I activity in the brain although the enzyme activity in mouse brain was 1% of the corresponding hepatic activity. We then examined the effect of this inhibition on the neurotoxicity mediated by the excitatory amino acid, l-beta-oxalyl amino-l-alanine, which is the causative factor of a type of motor neuron disease, neurolathyrism. l-beta-Oxalyl amino-l-alanine toxicity was exacerbated by l-propargylglycine measured as loss of complex I activity indicating the importance of cystathionine gamma-lyase in maintaining glutathione levels and in turn the mitochondrial function during excitotoxicity. Oxidative stress generated by l-beta-oxalyl amino-l-alanine itself inhibited cystathionine gamma-lyase, which could be prevented by prior treatment with thiol antioxidant. Thus, cystathionine gamma-lyase itself is susceptible to inactivation by oxidative stress and this can potentially exacerbate oxidant-induced damage. Cystathionine gamma-lyase is present in neuronal cells in human brain and its activity is several-fold higher compared to mouse brain. It could potentially play an important role in maintaining glutathione and protein thiol homeostasis in brain and hence afford neuroprotection.

Multifactor analysis of multiscaling in volatility return intervals.

PubMed

Wang, Fengzhong; Yamasaki, Kazuko; Havlin, Shlomo; Stanley, H Eugene

2009-01-01

We study the volatility time series of 1137 most traded stocks in the U.S. stock markets for the two-year period 2001-2002 and analyze their return intervals tau , which are time intervals between volatilities above a given threshold q . We explore the probability density function of tau , P_(q)(tau) , assuming a stretched exponential function, P_(q)(tau) approximately e;(-tau;(gamma)) . We find that the exponent gamma depends on the threshold in the range between q=1 and 6 standard deviations of the volatility. This finding supports the multiscaling nature of the return interval distribution. To better understand the multiscaling origin, we study how gamma depends on four essential factors, capitalization, risk, number of trades, and return. We show that gamma depends on the capitalization, risk, and return but almost does not depend on the number of trades. This suggests that gamma relates to the portfolio selection but not on the market activity. To further characterize the multiscaling of individual stocks, we fit the moments of tau , mu_(m) identical with(tautau);(m);(1m) , in the range of 10

The effect of tantalum on the structure/properties of two polycrystalline nickel-base superalloys: B-1900 + Hf MAR-M247. M.S. Thesis, Final Report

NASA Technical Reports Server (NTRS)

Janowski, G. M.

1985-01-01

The microstructure, phase compositions, and phase fractions were studied in conventionally cast B-1900 + Hf and both conventionally cast and directionally solidified MAR-M247 as a function of tantalum concentration. The hot tensile and creep rupture properties of the solutionized and aged MAR-M247-type alloys were also determined as a function of tantalum level. The effects of tantalum on the microstructure and phase compositions of B-1900 + Hf and MAR-M247 (conventionally cast and directionally solidified) were found to be very similar. The addition of tantalum to the as cast and heat treated alloys was shown to cause the partial replacement of the Hf in the MC carbides by Ta, although the degree of replacement was decreased by the solutionizing and aging heat treatment. The gamma prime and minor phase fractions (primarily MC type carbides) both increased approximately linearly with tantalum concentration. The gamma prime phase compositions were relatively insensitive to tantalum variations with the exception of the tantalum and/or hafnium levels. Bulk tantalum additions increased the tantalum, chromium, and cobalt levels of the gamma phase in both alloy series. The increase in the concentrations of the latter two elements in the gamma phase was a result of the decrease in the gamma phase fraction with increasing bulk tantalum concentration and constant gamma/gamma prime partitioning ratio. Tantalum additions increased the yield stress and ultimate tensile strength of the directionally solidified MAR-M247 type alloys and had no significant effect on ductility.

GABAergic modulation of visual gamma and alpha oscillations and its consequences for working memory performance.

PubMed

Lozano-Soldevilla, Diego; ter Huurne, Niels; Cools, Roshan; Jensen, Ole

2014-12-15

Impressive in vitro research in rodents and computational modeling has uncovered the core mechanisms responsible for generating neuronal oscillations. In particular, GABAergic interneurons play a crucial role for synchronizing neural populations. Do these mechanistic principles apply to human oscillations associated with function? To address this, we recorded ongoing brain activity using magnetoencephalography (MEG) in healthy human subjects participating in a double-blind pharmacological study receiving placebo, 0.5 mg and 1.5 mg of lorazepam (LZP; a benzodiazepine upregulating GABAergic conductance). Participants performed a demanding visuospatial working memory (WM) task. We found that occipital gamma power associated with WM recognition increased with LZP dosage. Importantly, the frequency of the gamma activity decreased with dosage, as predicted by models derived from the rat hippocampus. A regionally specific gamma increase correlated with the drug-related performance decrease. Despite the system-wide pharmacological intervention, gamma power drug modulations were specific to visual cortex: sensorimotor gamma power and frequency during button presses remained unaffected. In contrast, occipital alpha power modulations during the delay interval decreased parametrically with drug dosage, predicting performance impairment. Consistent with alpha oscillations reflecting functional inhibition, LZP affected alpha power strongly in early visual regions not required for the task demonstrating a regional specific occipital impairment. GABAergic interneurons are strongly implicated in the generation of gamma and alpha oscillations in human occipital cortex where drug-induced power modulations predicted WM performance. Our findings bring us an important step closer to linking neuronal dynamics to behavior by embracing established animal models. Copyright © 2014 Elsevier Ltd. All rights reserved.

Sensitivity to. gamma. rays of avian sarcoma and murine leukemia viruses. [/sup 60/Co, uv

DOE Office of Scientific and Technical Information (OSTI.GOV)

Toyoshima, K.; Niwa, O.; Yutsudo, M.

1980-09-01

The direct inactivation of avian and murine oncoviruses by ..gamma.. rays was examined using /sup 60/Co as a ..gamma..-ray source. The inactivation of murine leukemia virus (M-MuLV) followed single-hit kinetics while the subgroup D Schmidt-Ruppin strain of avian sarcoma virus (SR-RSV D) showed multihit inactivation kinetics with an extrapolation number of 5. The two viruses showed similar uv-inactivation kinetics. The genomic RNA of the SR-RSV D strain was degraded by ..gamma.. irradiation faster than its infectivity, but viral clones isolated from the foci formed after ..gamma.. irradiation had a complete genome. These results suggest that SR-RSV D has a strongmore » repair function, possibly connected with reverse transcriptase activity.« less

Neurofeedback training of gamma band oscillations improves perceptual processing.

PubMed

Salari, Neda; Büchel, Christian; Rose, Michael

2014-10-01

In this study, a noninvasive electroencephalography-based neurofeedback method is applied to train volunteers to deliberately increase gamma band oscillations (40 Hz) in the visual cortex. Gamma band oscillations in the visual cortex play a functional role in perceptual processing. In a previous study, we were able to demonstrate that gamma band oscillations prior to stimulus presentation have a significant influence on perceptual processing of visual stimuli. In the present study, we aimed to investigate longer lasting effects of gamma band neurofeedback training on perceptual processing. For this purpose, a feedback group was trained to modulate oscillations in the gamma band, while a control group participated in a task with an identical design setting but without gamma band feedback. Before and after training, both groups participated in a perceptual object detection task and a spatial attention task. Our results clearly revealed that only the feedback group but not the control group exhibited a visual processing advantage and an increase in oscillatory gamma band activity in the pre-stimulus period of the processing of the visual object stimuli after the neurofeedback training. Results of the spatial attention task showed no difference between the groups, which underlines the specific role of gamma band oscillations for perceptual processing. In summary, our results show that modulation of gamma band activity selectively affects perceptual processing and therefore supports the relevant role of gamma band activity for this specific process. Furthermore, our results demonstrate the eligibility of gamma band oscillations as a valuable tool for neurofeedback applications.

Electronic structures and nonlinear optical properties of trinuclear transition metal clusters M-(mu-S)-M' (M = Mo, W; M' = Cu, Ag, Au).

PubMed

Chen, Xihua; Wu, Kechen; Snijders, Jaap G; Lin, Chensheng

2003-01-27

A series of trinuclear metal clusters MS4(M'PPh3)2(M'PPh3) (M = Mo, W; M' = Cu, Ag, Au) have been studied using the density functional theory (DFT) method. The static polarizabilities and hyperpolarizabilities of the model clusters have been calculated using the finite-field (F-F) method. The model clusters, divided into two groups, are alike in the structure of two fragments of rhombic units M-(mu-S)2-M' (M = Mo, W; M' = Cu, Ag, Au), perpendicular to each other, which are joined by sharing the bridge metal M. It is the charge transfer from one of these moieties to the other in these characteristic sulfido-transitional metal cores that is responsible for the polarizabilities and hyperpolarizabilities. This kind of electronic delocalization, different from that of the planar pi-system, is interesting and warrants further investigation. The structural effects on properties are important. In these models, considerable third-order nonlinearities are exhibited. The element substitution effect of Mo and W is weak, while that of Cu and Ag is relatively substantial. An overall order is gamma xxxx(Mo-Ag) > gamma xxxx(W-Ag) > gamma xxxx(Mo-Au) > gamma xxxx(W-Au) > gamma xxxx (Mo-Cu) > gamma xxxx(W-Cu) and gamma av(Mo-Ag) approximately gamma av(W-Ag) > gamma av(Mo-Au) approximately gamma av(W-Au) approximately gamma av (Mo-Cu) approximately gamma av(W-Cu).

Simulation based evaluation of the designs of the Advanced Gamma-ray Imageing System (AGIS)

NASA Astrophysics Data System (ADS)

Bugaev, Slava; Buckley, James; Digel, Seth; Funk, Stephen; Konopelko, Alex; Krawczynski, Henric; Lebohec, Steohan; Maier, Gernot; Vassiliev, Vladimir

2009-05-01

The AGIS project under design study, is a large array of imaging atmospheric Cherenkov telescopes for gamma-rays astronomy between 40GeV and 100 TeV. In this paper we present the ongoing simulation effort to model the considered design approaches as a function of the main parameters such as array geometry, telescope optics and camera design in such a way the gamma ray observation capabilities can be optimized against the overall project cost.

Effect of asymmetric concentration profile on thermal conductivity in Ge/SiGe superlattices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hahn, Konstanze R., E-mail: konstanze.hahn@dsf.unica.it; Cecchi, Stefano; Colombo, Luciano

2016-05-16

The effect of the chemical composition in Si/Ge-based superlattices on their thermal conductivity has been investigated using molecular dynamics simulations. Simulation cells of Ge/SiGe superlattices have been generated with different concentration profiles such that the Si concentration follows a step-like, a tooth-saw, a Gaussian, and a gamma-type function in direction of the heat flux. The step-like and tooth-saw profiles mimic ideally sharp interfaces, whereas Gaussian and gamma-type profiles are smooth functions imitating atomic diffusion at the interface as obtained experimentally. Symmetry effects have been investigated comparing the symmetric profiles of the step-like and the Gaussian function to the asymmetric profilesmore » of the tooth-saw and the gamma-type function. At longer sample length and similar degree of interdiffusion, the thermal conductivity is found to be lower in asymmetric profiles. Furthermore, it is found that with smooth concentration profiles where atomic diffusion at the interface takes place the thermal conductivity is higher compared to systems with atomically sharp concentration profiles.« less

Lentivirus-ABCG1 instillation reduces lipid accumulation and improves lung compliance in GM-CSF knock-out mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Malur, Anagha; Huizar, Isham; Wells, Greg

2011-11-18

Highlights: Black-Right-Pointing-Pointer Lentivirus-ABCG1 reduces lipid accumulation in lungs of GM-CSF knock-out mice. Black-Right-Pointing-Pointer Up-regulation of ABCG1 improves lung function. Black-Right-Pointing-Pointer Upregulation of ABCG1 improves surfactant metabolism. -- Abstract: We have shown decreased expression of the nuclear transcription factor, peroxisome proliferator-activated receptor-gamma (PPAR{gamma}) and the PPAR{gamma}-regulated ATP-binding cassette transporter G1 (ABCG1) in alveolar macrophages from patients with pulmonary alveolar proteinosis (PAP). PAP patients also exhibit neutralizing antibodies to granulocyte-macrophage colony stimulating factor (GM-CSF), an upregulator of PPAR{gamma}. In association with functional GM-CSF deficiency, PAP lung is characterized by surfactant-filled alveolar spaces and lipid-filled alveolar macrophages. Similar pathology characterizes GM-CSF knock-out (KO)more » mice. We reported previously that intratracheal instillation of a lentivirus (lenti)-PPAR{gamma} plasmid into GM-CSF KO animals elevated ABCG1 and reduced alveolar macrophage lipid accumulation. Here, we hypothesized that instillation of lenti-ABCG1 might be sufficient to decrease lipid accumulation and improve pulmonary function in GM-CSF KO mice. Animals received intratracheal instillation of lenti-ABCG1 or control lenti-enhanced Green Fluorescent Protein (eGFP) plasmids and alveolar macrophages were harvested 10 days later. Alveolar macrophage transduction efficiency was 79% as shown by lenti-eGFP fluorescence. Quantitative PCR analyses indicated a threefold (p = 0.0005) increase in ABCG1 expression with no change of PPAR{gamma} or ABCA1 in alveolar macrophages of lenti-ABCG1 treated mice. ABCG1 was unchanged in control lenti-eGFP and PBS-instilled groups. Oil Red O staining detected reduced intracellular neutral lipid in alveolar macrophages from lenti-ABCG1 treated mice. Extracellular cholesterol and phospholipids were also decreased as shown by analysis of bronchoalveolar lavage fluid. Lung compliance was diminished in untreated GMCSF KO mice but improved significantly after lenti-ABCG1 treatment. Data demonstrate that in vivo instillation of lenti-ABCG1 in GM-CSF KO mice is sufficient to restore pulmonary homeostasis by: (1) upregulating ABCG1; (2) reducing intra and extracellular lipids; and (3) improving lung function. Results suggest that the ABCG1 lipid transporter is the key downstream target of GM-CSF-induced PPAR{gamma} necessary for surfactant catabolism.« less

Gamma oscillations: precise temporal coordination without a metronome.

PubMed

Nikolić, Danko; Fries, Pascal; Singer, Wolf

2013-02-01

Gamma oscillations in the brain should not be conceptualized as a sine wave with constant oscillation frequency. Rather, these oscillations serve to concentrate neuronal discharges to particular phases of the oscillation cycle and thereby provide the substrate for various, functionally relevant synchronization phenomena. Copyright © 2012 Elsevier Ltd. All rights reserved.

Polymerase Gamma Disease through the Ages

ERIC Educational Resources Information Center

Saneto, Russell P.; Naviaux, Robert K.

2010-01-01

The most common group of mitochondrial disease is due to mutations within the mitochondrial DNA polymerase, polymerase gamma 1 ("POLG"). This gene product is responsible for replication and repair of the small mitochondrial DNA genome. The structure-function relationship of this gene product produces a wide variety of diseases that at times, seems…

HLA-E upregulation on IFN-gamma-activated AML blasts impairs CD94/NKG2A-dependent NK cytolysis after haplo-mismatched hematopoietic SCT.

PubMed

Nguyen, S; Beziat, V; Dhedin, N; Kuentz, M; Vernant, J P; Debre, P; Vieillard, V

2009-05-01

Natural killer (NK) cells generated after haploidentical hematopoietic SCT in patients with AML are characterized by specific phenotypic features and impaired functioning that may affect transplantation outcome. We show that IFN-gamma produced by immature CD56(bright) NK cells upregulates cell surface expression of HLA-E on AML blasts and that this upregulation protects leukemic cells from NK-mediated cell lysis through the mediation of CD94/NKG2A, an inhibitory receptor overexpressed on NK cells after haploidentical SCT. Two years after transplantation, however, maturing NK cells were functionally active, as evidenced by high cytotoxicity and poor IFN-gamma production. This implies that maturation of NK cells is the key to improved immune responses and transplantation outcome.

Angular response calibration of the burst and transient source experiment

NASA Technical Reports Server (NTRS)

Lestrade, John Patrick

1988-01-01

The Gamma Ray Observatory includes four experiments designed to observe the gamma-ray universe. Laboratory measurements to test the response the Burst and Transient Source Experiment (BATSE) modules to gamma-ray sources that are non-axial were recently completed. The results of these observations are necessary for the correct interpretation of BATSE data obtained after it is put in Earth orbit. The launch is planned for March, 1900. Preliminary analyses of these test data show the presence of a radial dependence to the detector's light collection efficiency. It is proposed to evaluate the importance of this radial response, analyze future experimental data to derive the actual functional dependence on radius, and calculate the net effect on the output spectrum as a function of the angle of incidence.

Reduced gamma-aminobutyric acid concentration is associated with physical disability in progressive multiple sclerosis.

PubMed

Cawley, Niamh; Solanky, Bhavana S; Muhlert, Nils; Tur, Carmen; Edden, Richard A E; Wheeler-Kingshott, Claudia A M; Miller, David H; Thompson, Alan J; Ciccarelli, Olga

2015-09-01

Neurodegeneration is thought to be the major cause of ongoing, irreversible disability in progressive stages of multiple sclerosis. Gamma-aminobutyric acid is the principle inhibitory neurotransmitter in the brain. The aims of this study were to investigate if gamma-aminobutyric acid levels (i) are abnormal in patients with secondary progressive multiple sclerosis compared with healthy controls; and (ii) correlate with physical and cognitive performance in this patient population. Thirty patients with secondary progressive multiple sclerosis and 17 healthy control subjects underwent single-voxel MEGA-PRESS (MEscher-GArwood Point RESolved Spectroscopy) magnetic resonance spectroscopy at 3 T, to quantify gamma-aminobutyric acid levels in the prefrontal cortex, right hippocampus and left sensorimotor cortex. All subjects were assessed clinically and underwent a cognitive assessment. Multiple linear regression models were used to compare differences in gamma-aminobutyric acid concentrations between patients and controls adjusting for age, gender and tissue fractions within each spectroscopic voxel. Regression was used to examine the relationships between the cognitive function and physical disability scores specific for these regions with gamma-aminobuytric acid levels, adjusting for age, gender, and total N-acetyl-aspartate and glutamine-glutamate complex levels. When compared with controls, patients performed significantly worse on all motor and sensory tests, and were cognitively impaired in processing speed and verbal memory. Patients had significantly lower gamma-aminobutyric acid levels in the hippocampus (adjusted difference = -0.403 mM, 95% confidence intervals -0.792, -0.014, P = 0.043) and sensorimotor cortex (adjusted difference = -0.385 mM, 95% confidence intervals -0.667, -0.104, P = 0.009) compared with controls. In patients, reduced motor function in the right upper and lower limb was associated with lower gamma-aminobutyric acid concentration in the sensorimotor cortex. Specifically for each unit decrease in gamma-aminobutyric acid levels (in mM), there was a predicted -10.86 (95% confidence intervals -16.786 to -4.482) decrease in grip strength (kg force) (P < 0.001) and -8.74 (95% confidence intervals -13.943 to -3.015) decrease in muscle strength (P < 0.006). This study suggests that reduced gamma-aminobutyric acid levels reflect pathological abnormalities that may play a role in determining physical disability. These abnormalities may include decreases in the pre- and postsynaptic components of gamma-aminobutyric acid neurotransmission and in the density of inhibitory neurons. Additionally, the reduced gamma-aminobutyric acid concentration may contribute to the neurodegenerative process, resulting in increased firing of axons, with consequent increased energy demands, which may lead to neuroaxonal degeneration and loss of the compensatory mechanisms that maintain motor function. This study supports the idea that modulation of gamma-aminobutyric acid neurotransmission may be an important target for neuroprotection in multiple sclerosis.See De Stefano and Giorgio (doi:10.1093/brain/awv213) for a scientific commentary on this article. © The Author (2015). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Thiazolidinediones inhibit REG I{alpha} gene transcription in gastrointestinal cancer cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamauchi, Akiyo; Laboratory of Molecular Genetics, Tohoku University Graduate School of Pharmaceutical Sciences, Sendai 980-8578; Department of Biochemistry, Nara Medical University, Kashihara 634-8521

2009-02-13

REG (Regenerating gene) I{alpha} protein functions as a growth factor for gastrointestinal cancer cells, and its mRNA expression is strongly associated with a poor prognosis in gastrointestinal cancer patients. We here demonstrated that PPAR{gamma}-agonist thiazolidinediones (TZDs) inhibited cell proliferation and REG I{alpha} protein/mRNA expression in gastrointestinal cancer cells. TZDs inhibited the REG I{alpha} gene promoter activity, via its cis-acting element which lacked PPAR response element and could not bind to PPAR{gamma}, in PPAR{gamma}-expressing gastrointestinal cancer cells. The inhibition was reversed by co-treatment with a specific PPAR{gamma}-antagonist GW9662. Although TZDs did not inhibit the REG I{alpha} gene promoter activity in PPAR{gamma}-non-expressingmore » cells, PPAR{gamma} overexpression in the cells recovered their inhibitory effect. Taken together, TZDs inhibit REG I{alpha} gene transcription through a PPAR{gamma}-dependent pathway. The TZD-induced REG I{alpha} mRNA reduction was abolished by cycloheximide, indicating the necessity of novel protein(s) synthesis. TZDs may therefore be a candidate for novel anti-cancer drugs for patients with gastrointestinal cancer expressing both REG I{alpha} and PPAR{gamma}.« less

Distinct regulatory functions of SLP-76 and MIST in NK cell cytotoxicity and IFN-gamma production.

PubMed

Hidano, Shinya; Sasanuma, Hiroki; Ohshima, Keiko; Seino, Ken-ichiro; Kumar, Lalit; Hayashi, Katsuhiko; Hikida, Masaki; Kurosaki, Tomohiro; Taniguchi, Masaru; Geha, Raif S; Kitamura, Daisuke; Goitsuka, Ryo

2008-03-01

Activation of NK cells is triggered by multiple receptors. We demonstrate here that SLP-76 is required for CD16- and NKG2D-mediated NK cell cytotoxicity, while MIST negatively regulates these responses in an SLP-76-dependent manner. Exceptionally, MIST acts as a positive regulator of cytotoxicity against YAC-1 cells, although SLP-76 plays a more key role. SLP-76 acts as a dominant positive regulator for both NKG2D-mediated and YAC-1 cell-triggered IFN-gamma production. Although NKG2D-mediated IFN-gamma production depends on phospholipase C (PLC) gamma 2, YAC-1 cell-triggered IFN-gamma production is PLC gamma 2- and Syk/ZAP-70 independent and nuclear factor-kappa B mediated. SLP-76 is required for this process in the presence of MIST but is dispensable in the absence of MIST. Thus, YAC-1 cell-triggered NKG2D-independent IFN-gamma production appears to be regulated by SLP-76-dependent and -independent pathways, in which the latter is negatively regulated by MIST. Taken together, these results suggest that SLP-76 and MIST distinctly but interactively regulate NK cell cytotoxicity and IFN-gamma production.

The PPAR{gamma} coding region and its role in visceral obesity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boon Yin, Khoo; Institute for Research in Molecular Medicine; Najimudin, Nazalan

Peroxisome proliferator-activated receptor gamma (PPAR{gamma}) is a ligand activated transcription factor, plays many essential roles of biological function in higher organisms. The PPAR{gamma} is mainly expressed in adipose tissue. It regulates the transcriptional activity of genes by binding with other transcription factor. The PPAR{gamma} coding region has been found to be closest to that of monkey in ours and other research groups. Thus, monkey is a more suitable animal model for future PPAR{gamma} studying, although mice and rat are frequently being used. The PPAR{gamma} is involved in regulating alterations of adipose tissue masses result from changes in mature adipocyte sizemore » and/or number through a complex interplay process called adipogenesis. However, the role of PPAR{gamma} in negatively regulating the process of adipogenesis remains unclear. This review may help we investigate the differential expression of key transcription factor in adipose tissue in response to visceral obesity-induced diet in vivo. The study may also provide valuable information to define a more appropriate physiological condition in adipogenesis which may help to prevent diseases cause by negative regulation of the transcription factors in adipose tissue.« less

Transparent Ultra-High-Loading Quantum Dot/Polymer Nanocomposite Monolith for Gamma Scintillation.

PubMed

Liu, Chao; Li, Zhou; Hajagos, Tibor Jacob; Kishpaugh, David; Chen, Dustin Yuan; Pei, Qibing

2017-06-27

Spectroscopic gamma-photon detection has widespread applications for research, defense, and medical purposes. However, current commercial detectors are either prohibitively expensive for wide deployment or incapable of producing the characteristic gamma photopeak. Here we report the synthesis of transparent, ultra-high-loading (up to 60 wt %) Cd x Zn 1-x S/ZnS core/shell quantum dot/polymer nanocomposite monoliths for gamma scintillation by in situ copolymerization of the partially methacrylate-functionalized quantum dots in a monomer solution. The efficient Förster resonance energy transfer of the high-atomic-number quantum dots to lower-band-gap organic dyes enables the extraction of quantum-dot-borne excitons for photon production, resolving the problem of severe light yield deterioration found in previous nanoparticle-loaded scintillators. As a result, the nanocomposite scintillator exhibited simultaneous improvements in both light yield (visible photons produced per MeV of gamma-photon energy) and gamma attenuation. With these enhancements, a 662 keV Cs-137 gamma photopeak with 9.8% resolution has been detected using a 60 wt % quantum-dot nanocomposite scintillator, demonstrating the potential of such a nanocomposite system in the development of high-performance low-cost spectroscopic gamma detectors.

Moisture effect in prompt gamma measurements from soil samples.

PubMed

Naqvi, A A; Khiari, F Z; Liadi, F A; Khateeb-Ur-Rehman; Raashid, M A; Isab, A H

2016-09-01

The variation in intensity of 1.78MeV silicon, 6.13MeV oxygen, and 2.22MeV hydrogen prompt gamma rays from soil samples due to the addition of 5.1, 7.4, 9.7, 11.9 and 14.0wt% water was studied for 14MeV incident neutron beams utilizing a LaBr3:Ce gamma ray detector. The intensities of 1.78MeV and 6.13MeV gamma rays from silicon and oxygen, respectively, decreased with increasing sample moisture. The intensity of 2.22MeV hydrogen gamma rays increases with moisture. The decrease in intensity of silicon and oxygen gamma rays with moisture concentration indicates a loss of 14MeV neutron flux, while the increase in intensity of 2.22MeV gamma rays with moisture indicates an increase in thermal neutron flux due to increasing concentration of moisture. The experimental intensities of silicon, oxygen and hydrogen prompt gamma rays, measured as a function of moisture concentration in the soil samples, are in good agreement with the theoretical results obtained through Monte Carlo calculations. Copyright © 2016 Elsevier Ltd. All rights reserved.

Energy dependence of polarization across broad deexcitation gamma-ray line profiles

NASA Astrophysics Data System (ADS)

Werntz, Carl; Lang, F. L.

1998-04-01

The energy profiles of deexcitation gamma-ray lines from recoiling inelastically scattered nuclei exhibit detailed structure. MeV-wide gamma-ray lines from the direction of the Orion nebula have been detected (H. Bloemen, et al., Astr. and Astrophys. L5, 281 (1994).) by COMPTEL whose source is postulated to be cosmic ray carbon and oxygen nuclei shock accelerated near supernova remnants colliding with ambient hydrogen and helium. Even when the heavy ion velocity distributions are isotropic, structure characteristic of the multipolarity of the gamma transition remains (A. M. Bykov et al, Astr. and Astrophys. 607, L37 (1996); B. Kozlovsky et al, Astrophys. J. 484, (1997).). In experiments in which the energy dependent structure of the deexcitation gamma-ray profiles is not resolved, the gammas display a high degree of linear polarization that rapidly changes with gamma-beam angle. We calculate the polarization, both linear and circular, as a function of gamma-ray energy across the laboratory line profiles of C12*(4.44) and O16*(6.13) inelastically excited by protons and alphas. We then investigate the polarization in the surviving structures for isotropic energetic ions colliding with ^1H and ^4He.

AMPX: a modular code system for generating coupled multigroup neutron-gamma libraries from ENDF/B

DOE Office of Scientific and Technical Information (OSTI.GOV)

Greene, N.M.; Lucius, J.L.; Petrie, L.M.

1976-03-01

AMPX is a modular system for producing coupled multigroup neutron-gamma cross section sets. Basic neutron and gamma cross-section data for AMPX are obtained from ENDF/B libraries. Most commonly used operations required to generate and collapse multigroup cross-section sets are provided in the system. AMPX is flexibly dimensioned; neutron group structures, and gamma group structures, and expansion orders to represent anisotropic processes are all arbitrary and limited only by available computer core and budget. The basic processes provided will (1) generate multigroup neutron cross sections; (2) generate multigroup gamma cross sections; (3) generate gamma yields for gamma-producing neutron interactions; (4) combinemore » neutron cross sections, gamma cross sections, and gamma yields into final ''coupled sets''; (5) perform one-dimensional discrete ordinates transport or diffusion theory calculations for neutrons and gammas and, on option, collapse the cross sections to a broad-group structure, using the one-dimensional results as weighting functions; (6) plot cross sections, on option, to facilitate the ''evaluation'' of a particular multigroup set of data; (7) update and maintain multigroup cross section libraries in such a manner as to make it not only easy to combine new data with previously processed data but also to do it in a single pass on the computer; and (8) output multigroup cross sections in convenient formats for other codes. (auth)« less

Increased visual gamma power in schizoaffective bipolar disorder.

PubMed

Brealy, J A; Shaw, A; Richardson, H; Singh, K D; Muthukumaraswamy, S D; Keedwell, P A

2015-03-01

Electroencephalography and magnetoencephalography (MEG) studies have identified alterations in gamma-band (30-80 Hz) cortical activity in schizophrenia and mood disorders, consistent with neural models of disturbed glutamate (and GABA) neuron influence over cortical pyramidal cells. Genetic evidence suggests specific deficits in GABA-A receptor function in schizoaffective bipolar disorder (SABP), a clinical syndrome with features of both bipolar disorder and schizophrenia. This study investigated gamma oscillations in this under-researched disorder. MEG was used to measure induced gamma and evoked responses to a visual grating stimulus, known to be a potent inducer of primary visual gamma oscillations, in 15 individuals with remitted SABP, defined using Research Diagnostic Criteria, and 22 age- and sex-matched healthy controls. Individuals with SABP demonstrated increased sustained visual cortical power in the gamma band (t 35 = -2.56, p = 0.015) compared to controls. There were no group differences in baseline gamma power, transient or sustained gamma frequency, alpha band responses or pattern onset visual-evoked responses. Gamma power is increased in remitted SABP, which reflects an abnormality in the cortical inhibitory-excitatory balance. Although an interaction between gamma power and medication can not be ruled out, there were no group differences in evoked responses or baseline measures. Further work is needed in other clinical populations and at-risk relatives. Pharmaco-magnetoencephalography studies will help to elucidate the specific GABA and glutamate pathways affected.

Cortical volume and sex influence visual gamma.

PubMed

van Pelt, Stan; Shumskaya, Elena; Fries, Pascal

2018-06-05

Visually induced gamma-band activity (GBA) has been implicated in several central cognitive functions, in particular perceptual binding, the feedforward routing of attended stimulus information and memory encoding. Several studies have documented that the strength and frequency of GBA are influenced by both subject-intrinsic factors like age, and subject-extrinsic factors such as stimulus contrast. Here, we investigated the relative contributions of previously tested factors, additional factors, and their interactions, in a cohort of 158 subjects recorded with magnetoencephalography (MEG). In agreement with previous studies, we found that gamma strength and gamma peak frequency increase with stimulus contrast and stimulus velocity. Also in confirmation of previous findings, we report that gamma peak frequency declines with subject age. In addition, we found that gamma peak frequency is higher for subjects with thicker occipital cortex, but lower for larger occipital cortices. Also, gamma peak frequency is higher in female than male subjects. Extrinsic factors (stimulus contrast and velocity) and intrinsic factors (age, cortical thickness and sex) together explained 21% of the variance in gamma peak frequency and 20% of the variance in gamma strength. These results can contribute to our understanding of the mechanisms, by which gamma is generated, and the mechanisms, through which it affects the cognitive performance of a given individual subject. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

^235U(n,xnγ) Excitation Function Measurements Using Gamma-Ray Spectroscopy at GEANIE

NASA Astrophysics Data System (ADS)

Younes, W.; Becker, J. A.; Bernstein, L. A.; Archer, D. E.; Stoyer, M. A.; Hauschild, K.; Drake, D. M.; Johns, G. D.; Nelson, R. O.; Wilburn, S. W.

1998-04-01

The ^235U(n,xn) cross sections (where x<=2) have previously been measured at several incident neutron energies. In particular, the ^235U(n,2n) cross section has been measured(J. Frehaut et al.), Nucl. Sci. Eng. 74,29 (1980). reliably up to peak near E_n≈ 11 MeV, but not along the tail which is predicted by some(M.B. Chadwick, private communication.) codes to yield significant (e.g. >= 10% of peak) cross section out to E_n≈ 30 MeV. We have measured gamma-ray spectra resulting from ^235U(n,xn) as a function of neutron energy in the range 1 MeV <~ En <~ 200 MeV using the GEANIE spectrometer at the LANSCE/WNR ``white'' neutron source. We will present excitation functions for the de-excitation gamma rays in ^234,235U compared to predictions from the Hauser-Feshbach-preequilibrium code GNASH(M.B. Chadwick and P.G. Young, Los Alamos Report No. LA-UR-93-104, 1993.).

Determination of the nuclear level densities and radiative strength function for 43 nuclei in the mass interval 28≤A≤200

NASA Astrophysics Data System (ADS)

Knezevic, David; Jovancevic, Nikola; Sukhovoj, Anatoly M.; Mitsyna, Ludmila V.; Krmar, Miodrag; Cong, Vu D.; Hambsch, Franz-Josef; Oberstedt, Stephan; Revay, Zsolt; Stieghorst, Christian; Dragic, Aleksandar

2018-03-01

The determination of nuclear level densities and radiative strength functions is one of the most important tasks in low-energy nuclear physics. Accurate experimental values of these parameters are critical for the study of the fundamental properties of nuclear structure. The step-like structure in the dependence of the level densities p on the excitation energy of nuclei Eex is observed in the two-step gamma cascade measurements for nuclei in the 28 ≤ A ≤ 200 mass region. This characteristic structure can be explained only if a co-existence of quasi-particles and phonons, as well as their interaction in a nucleus, are taken into account in the process of gamma-decay. Here we present a new improvement to the Dubna practical model for the determination of nuclear level densities and radiative strength functions. The new practical model guarantees a good description of the available intensities of the two step gamma cascades, comparable to the experimental data accuracy.

Impairment of neutrophil Fc gamma receptor mediated transmembrane signalling in active rheumatoid arthritis.

PubMed Central

Goulding, N J; Guyre, P M

1992-01-01

Neutrophil Fc gamma receptor (Fc gamma R) signalling responses were compared in healthy subjects, patients with definite rheumatoid arthritis (RA), ankylosing spondylitis, and osteoarthritis. The patients with A were subdivided into those with active synovitis and those with quiescent disease. Basal intracellular calcium ion concentrations in patients with inactive RA were significantly higher than in control subjects, which in turn were greater than in patients with active RA. Transient cytosolic calcium ion fluxes were observed after binding Fc gamma RII or Fc gamma RIII with specific monoclonal antibodies and cross linking with the F(ab')2 fragment of antimouse IgG. Response times were significantly faster for Fc gamma RII than for Fc gamma RIII. Peak concentrations of intracellular calcium ions after neutrophil stimulation were comparable for Fc gamma RII and RIII in healthy subjects. Neutrophils in patients with ankylosing spondylitis and osteoarthritis responded to Fc gamma R triggering, but in the group with active RA fluxes of calcium ions were severely depressed. Neutrophils isolated from patients with RA with quiescent disease showed exaggerated responses when compared with controls. Expression of all three Fc gamma R types on neutrophils from patients with active RA, as measured by monoclonal antibody binding, was comparable with control cells. Impairment of neutrophil Fc gamma R cytosolic signalling in active RA could reflect a receptor signalling defect with potential effects on Fc mediated functions, or a fundamental defect in calcium ion homeostasis within these cells. PMID:1535494

Bruton's tyrosine kinase regulates B cell antigen receptor-mediated JNK1 response through Rac1 and phospholipase C-gamma2 activation.

PubMed

Inabe, Kazunori; Miyawaki, Toshio; Longnecker, Richard; Matsukura, Hiroyoshi; Tsukada, Satoshi; Kurosaki, Tomohiro

2002-03-13

Bruton's tyrosine kinase (Btk) is essential for B cell development and B cell antigen receptor (BCR) function. Recent studies have shown that Btk plays an important role in BCR-mediated c-Jun NH(2)-terminal kinase (JNK) 1 activation; however, the mechanism by which Btk participates in the JNK1 response remains elusive. Here we show that the BCR-mediated Rac1 activation is significantly inhibited by loss of Btk, while this Rac1 activation is not affected by loss of phospholipase C-gamma2 (PLC-gamma2). Since PLC-gamma2 is also required for BCR-mediated JNK1 response, our results suggest that Btk regulates Rac1 pathway as well as PLC-gamma2 pathway, both of which contribute to the BCR-mediated JNK1 response.

Attenuation of Neutron and Gamma Radiation by a Composite Material Based on Modified Titanium Hydride with a Varied Boron Content

NASA Astrophysics Data System (ADS)

Yastrebinskii, R. N.

2018-04-01

The investigations on estimating the attenuation of capture gamma radiation by a composite neutron-shielding material based on modified titanium hydride and Portland cement with a varied amount of boron carbide are performed. The results of calculations demonstrate that an introduction of boron into this material enables significantly decreasing the thermal neutron flux density and hence the levels of capture gamma radiation. In particular, after introducing 1- 5 wt.% boron carbide into the material, the thermal neutron flux density on a 10 cm-thick layer is reduced by 11 to 176 factors, and the capture gamma dose rate - from 4 to 9 times, respectively. The difference in the degree of reduction in these functionals is attributed to the presence of capture gamma radiation in the epithermal region of the neutron spectrum.

Modeled Martian subsurface elemental composition measurements with the Probing In situ with Neutron and Gamma ray instrument

NASA Astrophysics Data System (ADS)

Nowicki, Suzanne F.; Evans, Larry G.; Starr, Richard D.; Schweitzer, Jeffrey S.; Karunatillake, Suniti; McClanahan, Timothy P.; Moersch, Jeffrey E.; Parsons, Ann M.; Tate, Christopher G.

2017-02-01

The Probing In situ with Neutron and Gamma ray (PING) instrument is an innovative application of active neutron-induced gamma ray technology. The objective of PING is to measure the elemental composition of the Martian regolith. This manuscript presents PING's sensitivities as a function of the Martian regolith depth and PING's uncertainties in the measurements as a function of observation time in passive and active mode. The modeled sensitivities show that in PING's active mode, where both a pulsed neutron generator (PNG) and a gamma ray spectrometer (GRS) are used, PING can interrogate the material below the rover to about 20 cm due to the penetrating nature of the high-energy neutrons and the resulting secondary gamma rays observed with the GRS. PING is capable of identifying most major and minor rock-forming elements, including H, O, Na, Mn, Mg, Al, Si, P, S, Cl, Cr, K, Ca, Ti, Fe, and Th. The modeled uncertainties show that PING's use of a PNG reduces the required observation times by an order of magnitude over a passive operating mode where the PNG is turned off. While the active mode allows for more complete elemental inventories with higher sensitivity, the gamma ray signatures of some elements are strong enough to detect in passive mode. We show that PING can detect changes in key marker elements and make thermal neutron measurements in about 1 min that are sensitive to H and Cl.

The Luminosity Function of Fermi-detected Flat-Spectrum Radio Quasars

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ajello, M.; Shaw, M.S.; Romani, R.W.

2012-04-16

Fermi has provided the largest sample of {gamma}-ray selected blazars to date. In this work we use a complete sample of FSRQs detected during the first year of operation to determine the luminosity function (LF) and its evolution with cosmic time. The number density of FSRQs grows dramatically up to redshift {approx}0.5-2.0 and declines thereafter. The redshift of the peak in the density is luminosity dependent, with more luminous sources peaking at earlier times; thus the LF of {gamma}-ray FSRQs follows a luminosity-dependent density evolution similarly to that of radio-quiet AGN. Also using data from the Swift Burst Alert Telescopemore » we derive the average spectral energy distribution of FSRQs in the 10 keV-100GeV band and show that there is no correlation of the peak {gamma}-ray luminosity with {gamma}-ray peak frequency. The coupling of the SED and LF allows us to predict that the contribution of FSRQs to the Fermi isotropic {gamma}-ray background is 9.3{sub -1.0}{sup +1.6}% ({+-}3% systematic uncertainty) in the 0.1-100GeV band. Finally we determine the LF of unbeamed FSRQs, finding that FSRQs have an average Lorentz factor of {gamma} = 11.7{sub -2.2}{sup +3.3}, that most are seen within 5{sup o} of the jet axis, and that they represent only {approx}0.1% of the parent population.« less

Review of Livermore-Led Neutron Capture Studies Using DANCE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parker, W; Sheets, S; Agvaanluvsan, U

2007-05-11

We have made neutron capture cross-section measurements using the white neutron source at the Los Alamos Science Center, the DANCE detector array (Detector for Advanced Neutron Capture Experiments) and targets important for basic science and stockpile stewardship. In this paper, we review results from (n,{gamma}) reactions on {sup 94,95}Mo, {sup 152,154,157,160,nat}Gd, {sup 151,153}Eu and {sup 242m}Am for neutron energies from < 1eV up to {approx} 20 keV. We measured details of the {gamma}-ray cascade following neutron capture, for comparison with results of statistical model simulations. We determined the neutron energy dependent (n,{gamma}) cross section and gained information about statistical decaymore » properties, including the nuclear level density and the photon strength function. Because of the high granularity of the detector array, it is possible to look at gamma cascades with a specified number of transitions (a specific multiplicity). We simulated {gamma}-ray cascades using a combination of the DICEBOX/GEANT computer codes. In the case of the deformed nuclei, we found evidence of a scissors-mode resonance. For the Eu, we also determined the (n,{gamma}) cross sections. For the {sup 94,95}Mo, we focused on the spin and parity assignments of the resonances and the determination of the photon strength functions for the compound nuclei {sup 95,96}Mo. Future plans include measurements on actinide targets; our immediate interest is in {sup 242m}Am.« less

Enantioselective gamma- and delta-Borylation of Unsaturated Carbonyl Derivatives: Synthesis, Mechanistic Insights, and Applications

NASA Astrophysics Data System (ADS)

Hoang, Gia L.

Chiral boronic esters are valuable synthetic intermediates widely used in a variety of stereospecific transformations. Transition metal-catalyzed asymmetric hydroboration (CAHB) of alkenes is among the most popular methods for their preparation. Enantioselective hydroboration of activated alkenes (i.e., vinyl arene derivatives or conjugated carbonyl compounds) have been extensively studied by many research groups. We, on the other hand, are interested in enantioselective hydroboration of unactivated alkenes utilizing coordinating functional groups (e.g., carbonyl derivatives) to give functionalized, chiral boronic esters. While conjugate addition and C-H activation methodologies provide efficient alternatives to CAHB for enantioselective beta-borylation of carbonyl compounds, direct gamma- and delta-borylations were essentially unknown prior to our wok on CAHB. The gamma-borylated products were used for understanding stereochemical aspects of Suzuki-Miyaura cross-coupling reactions resulting in stereoretention and in contrast to similar beta-borylated carbonyl derivatives reported in literature. Some other selected transformations were carried out to construct a number of biologically relevant structural motifs, such as lignan precursors, 1,4-amino alcohols, gamma-amino acid derivatives, 5-substitued-gamma-lactone and lactam ring systems. In addition, collaborative experimental and computational studies of the enantioselective desymmetrization via CAHB gain a better understanding of the mechanistic pathways.

Implications of Gamma-Ray Transparency Constraints in Blazars: Minimum Distances and Gamma-Ray Collimation

NASA Technical Reports Server (NTRS)

Becker, Peter A.; Kafatos, Menas

1995-01-01

We develop a general expression for the gamma - gamma absorption coefficient, alpha(sub gamma(gamma)) for gamma-rays propagating in an arbitrary direction at an arbitrary point in space above an X-ray-emitting accretion disk. The X-ray intensity is assumed to vary as a power law in energy and radius between the outer disk radius, R(sub 0), and the inner radius, R(sub ms) which is the radius of marginal stability for a Schwarzschild black hole. We use our result for alpha(sub gamma(gamma)) to calculate the gamma - gamma optical depth, tau(sub gamma(gamma)) for gamma - rays created at height z and propagating at angle Phi relative to the disk axis, and we show that for Phi = 0 and z greater than or approx equal to R(sub 0), tau(sub gamma(gamma)) proportional to Epsilon(sup alpha)z(sup -2(alpha) - 3), where alpha is the X-ray spectral index and Epsilon is the gamma - ray energy. As an application, we use our formalism to compute the minimum distance between the central black hole and the site of production of the gamma-rays detected by EGRET during the 1991 June flare of 3C 279. In order to obtain an upper limit, we assume that all of the X-rays observed contemporaneously by Ginga were emitted by the disk. Our results suggest that the observed gamma - rays may have originated within less than or approx equal to 45 GM/sq c from a black hole of mass greater than or approx equal to 10(exp 9) solar mass, perhaps in active plasma located above the central funnel of the accretion disk. This raises the possibility of establishing a direct connection between the production of the observed gamma - rays and the accretion of material onto the black hole. We also consider the variation of the optical depth as a function of the angle of propagation Phi. Our results indicate that the "focusing" of the gamma - rays along the disk axis due to pair production is strong enough to explain the observed degree of alignment in blazar sources. If the gamma - rays are produced isotropically in gamma - ray blazars, then these objects should appear as bright MeV sources when viewed along off-axis lines of sight.

O-GlcNAc modification of PPAR{gamma} reduces its transcriptional activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ji, Suena; Park, Sang Yoon; Roth, Juergen

2012-01-27

Highlights: Black-Right-Pointing-Pointer We found that PPAR{gamma} is modified by O-GlcNAc in 3T3-L1 adipocytes. Black-Right-Pointing-Pointer The Thr54 of PPAR{gamma}1 is the major O-GlcNAc site. Black-Right-Pointing-Pointer Transcriptional activity of PPAR{gamma}1 was decreased on treatment with the OGA inhibitor. -- Abstract: The peroxisome proliferator-activated receptor {gamma} (PPAR{gamma}), a member of the nuclear receptor superfamily, is a key regulator of adipogenesis and is important for the homeostasis of the adipose tissue. The {beta}-O-linked N-acetylglucosamine (O-GlcNAc) modification, a posttranslational modification on various nuclear and cytoplasmic proteins, is involved in the regulation of protein function. Here, we report that PPAR{gamma} is modified by O-GlcNAc in 3T3-L1more » adipocytes. Mass spectrometric analysis and mutant studies revealed that the threonine 54 of the N-terminal AF-1 domain of PPAR{gamma} is the major O-GlcNAc site. Transcriptional activity of wild type PPAR{gamma} was decreased 30% by treatment with the specific O-GlcNAcase (OGA) inhibitor, but the T54A mutant of PPAR{gamma} did not respond to inhibitor treatment. In 3T3-L1 cells, an increase in O-GlcNAc modification by OGA inhibitor reduced PPAR{gamma} transcriptional activity and terminal adipocyte differentiation. Our results suggest that the O-GlcNAc state of PPAR{gamma} influences its transcriptional activity and is involved in adipocyte differentiation.« less

Sensory-driven and spontaneous gamma oscillations engage distinct cortical circuitry

PubMed Central

2015-01-01

Gamma oscillations are a robust component of sensory responses but are also part of the background spontaneous activity of the brain. To determine whether the properties of gamma oscillations in cortex are specific to their mechanism of generation, we compared in mouse visual cortex in vivo the laminar geometry and single-neuron rhythmicity of oscillations produced during sensory representation with those occurring spontaneously in the absence of stimulation. In mouse visual cortex under anesthesia (isoflurane and xylazine), visual stimulation triggered oscillations mainly between 20 and 50 Hz, which, because of their similar functional significance to gamma oscillations in higher mammals, we define here as gamma range. Sensory representation in visual cortex specifically increased gamma oscillation amplitude in the supragranular (L2/3) and granular (L4) layers and strongly entrained putative excitatory and inhibitory neurons in infragranular layers, while spontaneous gamma oscillations were distributed evenly through the cortical depth and primarily entrained putative inhibitory neurons in the infragranular (L5/6) cortical layers. The difference in laminar distribution of gamma oscillations during the two different conditions may result from differences in the source of excitatory input to the cortex. In addition, modulation of superficial gamma oscillation amplitude did not result in a corresponding change in deep-layer oscillations, suggesting that superficial and deep layers of cortex may utilize independent but related networks for gamma generation. These results demonstrate that stimulus-driven gamma oscillations engage cortical circuitry in a manner distinct from spontaneous oscillations and suggest multiple networks for the generation of gamma oscillations in cortex. PMID:26719085

Streptococcus thermophilus APC151 Strain Is Suitable for the Manufacture of Naturally GABA-Enriched Bioactive Yogurt

PubMed Central

Linares, Daniel M.; O’Callaghan, Tom F.; O’Connor, Paula M.; Ross, R. P.; Stanton, Catherine

2016-01-01

Consumer interest in health-promoting food products is a major driving force for the increasing global demand of functional (probiotic) dairy foods. Yogurt is considered the ideal medium for delivery of beneficial functional ingredients. Gamma-amino-butyric acid has potential as a bioactive ingredient in functional foods due to its health-promoting properties as an anti-stress, anti-hypertensive, and anti-diabetic agent. Here, we report the use of a novel Streptococcus thermophilus strain, isolated from the digestive tract of fish, for production of yogurt naturally enriched with 2 mg/ml of gamma-amino-butyric acid (200 mg in a standard yogurt volume of 100 ml), a dose in the same range as that provided by some commercially available gamma-amino-butyric acid supplements. The biotechnological suitability of this strain for industrial production of yogurt was demonstrated by comparison with the reference yogurt inoculated with the commercial CH1 starter (Chr. Hansen) widely used in the dairy industry. Both yogurts showed comparable pH curves [ΔpH/Δt = 0.31-0.33 h-1], viscosity [0.49 Pa-s], water holding capacity [72–73%], and chemical composition [moisture (87–88%), protein (5.05–5.65%), fat (0.12–0.15%), sugar (4.8–5.8%), and ash (0.74–1.2%)]. Gamma-amino-butyric acid was not detected in the control yogurt. In conclusion, the S. thermophilus APC151 strain reported here provides a natural means for fortification of yogurt with gamma-amino-butyric acid. PMID:27920772

Beta and gamma oscillatory activities associated with olfactory memory tasks: different rhythms for different functional networks?

PubMed Central

Martin, Claire; Ravel, Nadine

2014-01-01

Olfactory processing in behaving animals, even at early stages, is inextricable from top down influences associated with odor perception. The anatomy of the olfactory network (olfactory bulb, piriform, and entorhinal cortices) and its unique direct access to the limbic system makes it particularly attractive to study how sensory processing could be modulated by learning and memory. Moreover, olfactory structures have been early reported to exhibit oscillatory population activities easy to capture through local field potential recordings. An attractive hypothesis is that neuronal oscillations would serve to “bind” distant structures to reach a unified and coherent perception. In relation to this hypothesis, we will assess the functional relevance of different types of oscillatory activity observed in the olfactory system of behaving animals. This review will focus primarily on two types of oscillatory activities: beta (15–40 Hz) and gamma (60–100 Hz). While gamma oscillations are dominant in the olfactory system in the absence of odorant, both beta and gamma rhythms have been reported to be modulated depending on the nature of the olfactory task. Studies from the authors of the present review and other groups brought evidence for a link between these oscillations and behavioral changes induced by olfactory learning. However, differences in studies led to divergent interpretations concerning the respective role of these oscillations in olfactory processing. Based on a critical reexamination of those data, we propose hypotheses on the functional involvement of beta and gamma oscillations for odor perception and memory. PMID:25002840

The gamma-ray pulsar population of globular clusters: implications for the GeV excess

NASA Astrophysics Data System (ADS)

Hooper, Dan; Linden, Tim

2016-08-01

It has been suggested that the GeV excess, observed from the region surrounding the Galactic Center, might originate from a population of millisecond pulsars that formed in globular clusters. With this in mind, we employ the publicly available Fermi data to study the gamma-ray emission from 157 globular clusters, identifying a statistically significant signal from 25 of these sources (ten of which are not found in existing gamma-ray catalogs). We combine these observations with the predicted pulsar formation rate based on the stellar encounter rate of each globular cluster to constrain the gamma-ray luminosity function of millisecond pulsars in the Milky Way's globular cluster system. We find that this pulsar population exhibits a luminosity function that is quite similar to those millisecond pulsars observed in the field of the Milky Way (i.e. the thick disk). After pulsars are expelled from a globular cluster, however, they continue to lose rotational kinetic energy and become less luminous, causing their luminosity function to depart from the steady-state distribution. Using this luminosity function and a model for the globular cluster disruption rate, we show that millisecond pulsars born in globular clusters can account for only a few percent or less of the observed GeV excess. Among other challenges, scenarios in which the entire GeV excess is generated from such pulsars are in conflict with the observed mass of the Milky Way's Central Stellar Cluster.

The gamma-ray pulsar population of globular clusters: implications for the GeV excess

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hooper, Dan; Linden, Tim, E-mail: dhooper@fnal.gov, E-mail: linden.70@osu.edu

It has been suggested that the GeV excess, observed from the region surrounding the Galactic Center, might originate from a population of millisecond pulsars that formed in globular clusters. With this in mind, we employ the publicly available Fermi data to study the gamma-ray emission from 157 globular clusters, identifying a statistically significant signal from 25 of these sources (ten of which are not found in existing gamma-ray catalogs). We combine these observations with the predicted pulsar formation rate based on the stellar encounter rate of each globular cluster to constrain the gamma-ray luminosity function of millisecond pulsars in themore » Milky Way's globular cluster system. We find that this pulsar population exhibits a luminosity function that is quite similar to those millisecond pulsars observed in the field of the Milky Way (i.e. the thick disk). After pulsars are expelled from a globular cluster, however, they continue to lose rotational kinetic energy and become less luminous, causing their luminosity function to depart from the steady-state distribution. Using this luminosity function and a model for the globular cluster disruption rate, we show that millisecond pulsars born in globular clusters can account for only a few percent or less of the observed GeV excess. Among other challenges, scenarios in which the entire GeV excess is generated from such pulsars are in conflict with the observed mass of the Milky Way's Central Stellar Cluster.« less

The gamma-ray pulsar population of globular clusters: Implications for the GeV excess

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hooper, Dan; Linden, Tim

In this study, it has been suggested that the GeV excess, observed from the region surrounding the Galactic Center, might originate from a population of millisecond pulsars that formed in globular clusters. With this in mind, we employ the publicly available Fermi data to study the gamma-ray emission from 157 globular clusters, identifying a statistically significant signal from 25 of these sources (ten of which are not found in existing gamma-ray catalogs). We combine these observations with the predicted pulsar formation rate based on the stellar encounter rate of each globular cluster to constrain the gamma-ray luminosity function of millisecondmore » pulsars in the Milky Way's globular cluster system. We find that this pulsar population exhibits a luminosity function that is quite similar to those millisecond pulsars observed in the field of the Milky Way (i.e. the thick disk). After pulsars are expelled from a globular cluster, however, they continue to lose rotational kinetic energy and become less luminous, causing their luminosity function to depart from the steady-state distribution. Using this luminosity function and a model for the globular cluster disruption rate, we show that millisecond pulsars born in globular clusters can account for only a few percent or less of the observed GeV excess. Among other challenges, scenarios in which the entire GeV excess is generated from such pulsars are in conflict with the observed mass of the Milky Way's Central Stellar Cluster.« less

The gamma-ray pulsar population of globular clusters: Implications for the GeV excess

DOE PAGES

Hooper, Dan; Linden, Tim

2016-08-09

In this study, it has been suggested that the GeV excess, observed from the region surrounding the Galactic Center, might originate from a population of millisecond pulsars that formed in globular clusters. With this in mind, we employ the publicly available Fermi data to study the gamma-ray emission from 157 globular clusters, identifying a statistically significant signal from 25 of these sources (ten of which are not found in existing gamma-ray catalogs). We combine these observations with the predicted pulsar formation rate based on the stellar encounter rate of each globular cluster to constrain the gamma-ray luminosity function of millisecondmore » pulsars in the Milky Way's globular cluster system. We find that this pulsar population exhibits a luminosity function that is quite similar to those millisecond pulsars observed in the field of the Milky Way (i.e. the thick disk). After pulsars are expelled from a globular cluster, however, they continue to lose rotational kinetic energy and become less luminous, causing their luminosity function to depart from the steady-state distribution. Using this luminosity function and a model for the globular cluster disruption rate, we show that millisecond pulsars born in globular clusters can account for only a few percent or less of the observed GeV excess. Among other challenges, scenarios in which the entire GeV excess is generated from such pulsars are in conflict with the observed mass of the Milky Way's Central Stellar Cluster.« less

Ablation of the 14-3-3gamma Protein Results in Neuronal Migration Delay and Morphological Defects in the Developing Cerebral Cortex.

PubMed

Wachi, Tomoka; Cornell, Brett; Marshall, Courtney; Zhukarev, Vladimir; Baas, Peter W; Toyo-oka, Kazuhito

2016-06-01

14-3-3 proteins are ubiquitously-expressed and multifunctional proteins. There are seven isoforms in mammals with a high level of homology, suggesting potential functional redundancy. We previously found that two of seven isoforms, 14-3-3epsilon and 14-3-3zeta, are important for brain development, in particular, radial migration of pyramidal neurons in the developing cerebral cortex. In this work, we analyzed the function of another isoform, the protein 14-3-3gamma, with respect to neuronal migration in the developing cortex. We found that in utero 14-3-3gamma-deficiency resulted in delays in neuronal migration as well as morphological defects. Migrating neurons deficient in 14-3-3gamma displayed a thicker leading process stem, and the basal ends of neurons were not able to reach the boundary between the cortical plate and the marginal zone. Consistent with the results obtained from in utero electroporation, time-lapse live imaging of brain slices revealed that the ablation of the 14-3-3gamma proteins in pyramidal neurons slowed down their migration. In addition, the 14-3-3gamma deficient neurons showed morphological abnormalities, including increased multipolar neurons with a thicker leading processes stem during migration. These results indicate that the 14-3-3gamma proteins play an important role in radial migration by regulating the morphology of migrating neurons in the cerebral cortex. The findings underscore the pathological phenotypes of brain development associated with the disruption of different 14-3-3 proteins and will advance the preclinical data regarding disorders caused by neuronal migration defects. © 2015 Wiley Periodicals, Inc.

Modeled Martian subsurface elemental composition measurements with the Probing In situ with Neutron and Gamma ray instrument: Gamma and Neutron Measurements on Mars

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nowicki, Suzanne F.; Evans, Larry G.; Starr, Richard D.

Here, the Probing In situ with Neutrons and Gamma rays (PING) instrument is an innovative application of active neutron-induced gamma-ray technology. The objective of PING is to measure the elemental composition of the Martian regolith. As part 2 of a two-part submission, this manuscript presents PING's sensitivities as a function of the Martian regolith depth and PING's uncertainties in the measurements as a function of observation time in passive and active mode. Part 1 of our submission models the associated regolith types. The modeled sensitivities show that in PING's active mode, where both a Pulsed Neutron Generator (PNG) and amore » Gamma-Ray Spectrometer (GRS) are used, PING can interrogate the material below the rover to about 20 cm due to the penetrating nature of the high-energy neutrons and the resulting secondary gamma rays observed with the GRS. PING is capable of identifying most major and minor rock-forming elements, including H, O, Na, Mn, Mg, Al, Si, P, S, Cl, Cr, K, Ca, Ti, Fe and Th. The modeled uncertainties show that PING's use of a PNG reduces the required observation times by an order of magnitude over a passive operating mode where the PNG is turned off. While the active mode allows for more complete elemental inventories with higher sensitivity, the gamma-ray signatures of some elements are strong enough to detect in passive mode. We show that PING can detect changes in key marker elements and make thermal neutron measurements in about 1 minute that are sensitive to H and Cl.« less

Modeled Martian subsurface elemental composition measurements with the Probing In situ with Neutron and Gamma ray instrument: Gamma and Neutron Measurements on Mars

DOE PAGES

Nowicki, Suzanne F.; Evans, Larry G.; Starr, Richard D.; ...

2017-02-01

Here, the Probing In situ with Neutrons and Gamma rays (PING) instrument is an innovative application of active neutron-induced gamma-ray technology. The objective of PING is to measure the elemental composition of the Martian regolith. As part 2 of a two-part submission, this manuscript presents PING's sensitivities as a function of the Martian regolith depth and PING's uncertainties in the measurements as a function of observation time in passive and active mode. Part 1 of our submission models the associated regolith types. The modeled sensitivities show that in PING's active mode, where both a Pulsed Neutron Generator (PNG) and amore » Gamma-Ray Spectrometer (GRS) are used, PING can interrogate the material below the rover to about 20 cm due to the penetrating nature of the high-energy neutrons and the resulting secondary gamma rays observed with the GRS. PING is capable of identifying most major and minor rock-forming elements, including H, O, Na, Mn, Mg, Al, Si, P, S, Cl, Cr, K, Ca, Ti, Fe and Th. The modeled uncertainties show that PING's use of a PNG reduces the required observation times by an order of magnitude over a passive operating mode where the PNG is turned off. While the active mode allows for more complete elemental inventories with higher sensitivity, the gamma-ray signatures of some elements are strong enough to detect in passive mode. We show that PING can detect changes in key marker elements and make thermal neutron measurements in about 1 minute that are sensitive to H and Cl.« less

Unraveling Fungal Radiation Resistance Regulatory Networks through the Genome-Wide Transcriptome and Genetic Analyses of Cryptococcus neoformans

PubMed Central

Jung, Kwang-Woo; Yang, Dong-Hoon; Kim, Min-Kyu; Seo, Ho Seong

2016-01-01

ABSTRACT The basidiomycetous fungus Cryptococcus neoformans has been known to be highly radiation resistant and has been found in fatal radioactive environments such as the damaged nuclear reactor at Chernobyl. To elucidate the mechanisms underlying the radiation resistance phenotype of C. neoformans, we identified genes affected by gamma radiation through genome-wide transcriptome analysis and characterized their functions. We found that genes involved in DNA damage repair systems were upregulated in response to gamma radiation. Particularly, deletion of recombinase RAD51 and two DNA-dependent ATPase genes, RAD54 and RDH54, increased cellular susceptibility to both gamma radiation and DNA-damaging agents. A variety of oxidative stress response genes were also upregulated. Among them, sulfiredoxin contributed to gamma radiation resistance in a peroxiredoxin/thioredoxin-independent manner. Furthermore, we found that genes involved in molecular chaperone expression, ubiquitination systems, and autophagy were induced, whereas genes involved in the biosynthesis of proteins and fatty acids/sterols were downregulated. Most importantly, we discovered a number of novel C. neoformans genes, the expression of which was modulated by gamma radiation exposure, and their deletion rendered cells susceptible to gamma radiation exposure, as well as DNA damage insults. Among these genes, we found that a unique transcription factor containing the basic leucine zipper domain, named Bdr1, served as a regulator of the gamma radiation resistance of C. neoformans by controlling expression of DNA repair genes, and its expression was regulated by the evolutionarily conserved DNA damage response protein kinase Rad53. Taken together, the current transcriptome and functional analyses contribute to the understanding of the unique molecular mechanism of the radiation-resistant fungus C. neoformans. PMID:27899501

DNA microarray analyses reveal a post-irradiation differential time-dependent gene expression profile in yeast cells exposed to X-rays and gamma-rays.

PubMed

Kimura, Shinzo; Ishidou, Emi; Kurita, Sakiko; Suzuki, Yoshiteru; Shibato, Junko; Rakwal, Randeep; Iwahashi, Hitoshi

2006-07-21

Ionizing radiation (IR) is the most enigmatic of genotoxic stress inducers in our environment that has been around from the eons of time. IR is generally considered harmful, and has been the subject of numerous studies, mostly looking at the DNA damaging effects in cells and the repair mechanisms therein. Moreover, few studies have focused on large-scale identification of cellular responses to IR, and to this end, we describe here an initial study on the transcriptional responses of the unicellular genome model, yeast (Saccharomyces cerevisiae strain S288C), by cDNA microarray. The effect of two different IR, X-rays, and gamma (gamma)-rays, was investigated by irradiating the yeast cells cultured in YPD medium with 50 Gy doses of X- and gamma-rays, followed by resuspension of the cells in YPD for time-course experiments. The samples were collected for microarray analysis at 20, 40, and 80 min after irradiation. Microarray analysis revealed a time-course transcriptional profile of changed gene expressions. Up-regulated genes belonged to the functional categories mainly related to cell cycle and DNA processing, cell rescue defense and virulence, protein and cell fate, and metabolism (X- and gamma-rays). Similarly, for X- and gamma-rays, the down-regulated genes belonged to mostly transcription and protein synthesis, cell cycle and DNA processing, control of cellular organization, cell fate, and C-compound and carbohydrate metabolism categories, respectively. This study provides for the first time a snapshot of the genome-wide mRNA expression profiles in X- and gamma-ray post-irradiated yeast cells and comparatively interprets/discusses the changed gene functional categories as effects of these two radiations vis-à-vis their energy levels.

Opposite effects of lateralised transcranial alpha versus gamma stimulation on auditory spatial attention.

PubMed

Wöstmann, Malte; Vosskuhl, Johannes; Obleser, Jonas; Herrmann, Christoph S

2018-04-06

Spatial attention relatively increases the power of neural 10-Hz alpha oscillations in the hemisphere ipsilateral to attention, and decreases alpha power in the contralateral hemisphere. For gamma oscillations (>40 Hz), the opposite effect has been observed. The functional roles of lateralised oscillations for attention are currently unclear. If lateralised oscillations are functionally relevant for attention, transcranial stimulation of alpha versus gamma oscillations in one hemisphere should differentially modulate the accuracy of spatial attention to the ipsi-versus contralateral side. 20 human participants performed a dichotic listening task under continuous transcranial alternating current stimulation (tACS, vs sham) at alpha (10 Hz) or gamma (47 Hz) frequency. On each trial, participants attended to four spoken numbers on the left or right ear, while ignoring numbers on the other ear. In order to stimulate a left temporo-parietal cortex region, which is known to show marked modulations of alpha power during auditory spatial attention, tACS (1 mA peak-to-peak amplitude) was applied at electrode positions TP7 and FC5 over the left hemisphere. As predicted, unihemispheric alpha-tACS relatively decreased the recall of targets contralateral to stimulation, but increased recall of ipsilateral targets. Importantly, this spatial pattern of results was reversed for gamma-tACS. Results provide a proof of concept that transcranially stimulated oscillations can enhance spatial attention and facilitate attentional selection of speech. Furthermore, opposite effects of alpha versus gamma stimulation support the view that states of high alpha are incommensurate with active neural processing as reflected by states of high gamma. Copyright © 2018 Elsevier Inc. All rights reserved.

7Be(p,gamma)8B S-factor from Ab Initio Wave Functions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Navratil, P; Bertulani, C A; Caurier, E

2006-10-12

There has been a significant progress in ab initio approaches to the structure of light nuclei. Starting from realistic two- and three-nucleon interactions the ab initio no-core shell model (NCSM) predicts low-lying levels in p-shell nuclei. It is a challenging task to extend ab initio methods to describe nuclear reactions. We present here a brief overview of the first steps taken toward nuclear reaction applications. In particular, we discuss our calculation of the {sup 7}Be(p,{gamma}){sup 8}B S-factor. We also present our first results of the {sup 3}He({alpha},{gamma}){sup 7}Be S-factor and of the S-factor of the mirror reaction {sup 3}H({alpha},{gamma}){sup 7}Li.more » The {sup 7}Be(p,{gamma}){sup 8}B and {sup 3}He({alpha},{gamma}){sup 7}Be reactions correspond to the most important uncertainties in solar model predictions of neutrino fluxes.« less

Gamma frequency entrainment attenuates amyloid load and modifies microglia

PubMed Central

Iaccarino, Hannah F.; Singer, Annabelle C.; Martorell, Anthony J.; Rudenko, Andrii; Gao, Fan; Gillingham, Tyler Z.; Mathys, Hansruedi; Seo, Jinsoo; Kritskiy, Oleg; Abdurrob, Fatema; Adaikkan, Chinnakkaruppan; Canter, Rebecca G.; Rueda, Richard; Brown, Emery N.; Boyden, Edward S.; Tsai, Li-Huei

2017-01-01

Changes in gamma oscillations (20-50 Hz) have been observed in several neurological disorders. However, the relationship between gamma and cellular pathologies is unclear. Here, we show reduced behaviorally-driven gamma before the onset of plaque formation or cognitive decline in a mouse model of Alzheimer's disease (AD). Optogenetically driving FS-PV-interneurons at gamma (40 Hz), but not other frequencies, reduced levels of amyloid-β (A β)1-40 and A β1-42 isoforms. Gene expression profiling revealed induction of genes associated with morphological transformation of microglia and histological analysis confirmed increased microglia co-localization with A β. Subsequently, we designed a non-invasive 40 Hz light-flickering paradigm that reduced A β1-40 and A β1-42 levels in visual cortex of pre-depositing mice and mitigated plaque load in aged, depositing mice. Our findings uncover a previously unappreciated function of gamma rhythms in recruiting both neuronal and glial responses to attenuate AD-associated pathology. PMID:27929004

Gamma-ray luminosity and photon index evolution of FSRQ blazars and contribution to the gamma-ray background

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singal, J.; Ko, A.; Petrosian, V., E-mail: jsingal@richmond.edu

We present the redshift evolutions and distributions of the gamma-ray luminosity and photon spectral index of flat spectrum radio quasar (FSRQ) type blazars, using non-parametric methods to obtain the evolutions and distributions directly from the data. The sample we use for analysis consists of almost all FSRQs observed with a greater than approximately 7σ detection threshold in the first-year catalog of the Fermi Gamma-ray Space Telescope's Large Area Telescope, with redshifts as determined from optical spectroscopy by Shaw et al. We find that FSQRs undergo rapid gamma-ray luminosity evolution, but negligible photon index evolution, with redshift. With these evolutions accountedmore » for we determine the density evolution and luminosity function of FSRQs and calculate their total contribution to the extragalactic gamma-ray background radiation, resolved and unresolved, which is found to be 16(+10/–4)%, in agreement with previous studies.« less

Test of the statistical model in {sup 96}Mo with the BaF{sub 2}{gamma} calorimeter DANCE array

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sheets, S. A.; Mitchell, G. E.; Agvaanluvsan, U.

2009-02-15

The {gamma}-ray cascades following the {sup 95}Mo(n,{gamma}){sup 96}Mo reaction were studied with the {gamma} calorimeter DANCE (Detector for Advanced Neutron Capture Experiments) consisting of 160 BaF{sub 2} scintillation detectors at the Los Alamos Neutron Science Center. The {gamma}-ray energy spectra for different multiplicities were measured for s- and p-wave resonances below 2 keV. The shapes of these spectra were found to be in very good agreement with simulations using the DICEBOX statistical model code. The relevant model parameters used for the level density and photon strength functions were identical with those that provided the best fit of the data frommore » a recent measurement of the thermal {sup 95}Mo(n,{gamma}){sup 96}Mo reaction with the two-step-cascade method. The reported results strongly suggest that the extreme statistical model works very well in the mass region near A=100.« less

Human gamma-frequency oscillations associated with attention and memory.

PubMed

Jensen, Ole; Kaiser, Jochen; Lachaux, Jean-Philippe

2007-07-01

Both theoretical and experimental animal work supports the hypothesis that transient oscillatory synchronization of neuronal assemblies at gamma frequencies (30-100 Hz) is closely associated with sensory processing. Recent data from recordings in animals and humans have suggested that gamma-frequency activity also has an important role in attention and both working and long-term memory. The involvement of gamma-band synchronization in various cognitive paradigms in humans is currently being investigated using intracranial and high-density electro- and magnetoencephalography recordings. Here, we discuss recent findings demonstrating human gamma-frequency activity associated with attention and memory in both sensory and non-sensory areas. Because oscillatory gamma-frequency activity has an important role in neuronal communication and synaptic plasticity, it could provide a key for understanding neuronal processing in both local and distributed cortical networks engaged in complex cognitive functions. This review is part of the INMED/TINS special issue Physiogenic and pathogenic oscillations: the beauty and the beast, based on presentations at the annual INMED/TINS symposium (http://inmednet.com).

The control and data acquisition structure for the GAMMA-400 space gamma-telescope

NASA Astrophysics Data System (ADS)

Arkhangelskiy, Andrey

2016-07-01

The GAMMA-400 space project is intended for precision investigation of the cosmic gamma-emission in the energy band from keV region up to several TeV, electrons and positrons fluxes from ˜~1~GeV up to ˜~10~TeV and high energy cosmic-ray nuclei fluxes. A description of the control and data acquisition structure for gamma-telescope involved in the GAMMA 400 space project is given. The technical capabilities of all specialized equipment providing the functioning of the scientific instrumentation and satellite support systems are unified in a single structure. Control of the scientific instruments is maintained using one-time pulse radio commands and program commands transmitted via onboard control system and scientific data acquisition system. Up to 100~GByte of data per day can be transferred to the ground segment of the project. The correctness of the proposed and implemented structure, engineering solutions and electronic elemental base selection has been verified experimentally with the scientific complex prototype in the laboratory conditions.

Degradation kinetics of gamma-oryzanol in antioxidant-stripped rice bran oil during thermal oxidation.

PubMed

Khuwijitjaru, Pramote; Yuenyong, Thippawan; Pongsawatmanit, Rungnaphar; Adachi, Shuji

2009-01-01

Gamma-oryzanol, a group of phytosterol ferulates found in rice bran, possesses antioxidative activity and other bioactivities. The kinetics of thermal degradation of gamma-oryzanol in stripped rice bran oil (SRBO) were investigated under heating at 132, 160, 192 and 222 degrees C for 480, 140, 60 and 50 h, respectively. Losses of the overall gamma-oryzanol and its components (cycloartenyl ferulate, 24-methylene cycloartanyl ferulate, campesteryl ferulate and beta-sitosteryl ferulate) could be expressed by the first-order kinetics model. The rate constant of thermal degradation of gamma-oryzanol increased with increasing heating temperatures. The temperature dependence of the obtained rate constants was found to obey the Arrhenius equation. Campesteryl ferulate showed slightly more thermally resistant than other components at temperature lower than 160 degrees C. However, the change in the absorbance from 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay as a function of heating time exhibited the same pattern for the SRBO with and without gamma-oryzanol for all studied heating temperatures.

Simultaneous observation of the gamma-ray binary LS I+61 303 with GLAST and Suzaku

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tanaka, Takuya; Fukazawa, Yasushi; Mizuno, Tsunefumi

2007-07-12

The gamma-ray binary LS I+61 303 is a bright gamma-ray source, and thus an attracting object for GLAST. We proposed to observe this object with the X-ray satellite Suzaku (AO-2), simultaneously with GLAST, radio wave, and optical spectro-polarimetry, in order to probe the geometrical state of the binary system emitting the gamma-ray radiation, as a function of the binary orbital phase for the first time. This is essential to understand the mechanism of jet production and gamma-ray emission. The idea is not only to measure the multi-band overall continuum shape, but also to make use of continuous monitoring capability ofmore » GLAST, wide X-ray band of Suzaku, and good accessibility of the Kanata optical/NIR telescope (Hiroshima University) with the sensitive optical spectro-polarimetry. Further collaboration with TeV gamma-ray telescopes is also hoped to constrain the jet constitution.« less

Effect of short-term enteral feeding with eicosapentaenoic and gamma-linolenic acids on alveolar macrophage eicosanoid synthesis and bactericidal function in rats.

PubMed

Palombo, J D; DeMichele, S J; Boyce, P J; Lydon, E E; Liu, J W; Huang, Y S; Forse, R A; Mizgerd, J P; Bistrian, B R

1999-09-01

Because vasoactive eicosanoids derived from arachidonic acid present in immune cell phospholipids promote lung inflammation in critically ill patients, novel experimental diets containing eicosapentaenoic acid from fish oil and gamma-linolenic acid from borage oil have been designed to limit arachidonic acid metabolism. However, excess dietary eicosapentaenoic acid impairs superoxide formation and bacterial killing by immune cells. The present study determined whether short-term enteral feeding with diets enriched with either eicosapentaenoic acid alone or in combination with gamma-linolenic acid would modulate alveolar macrophage eicosanoid synthesis without compromising bactericidal function. Prospective, randomized, controlled, blinded study. University medical center. Adult male Sprague-Dawley rats. Rats underwent surgical placement of a gastroduodenal feeding catheter and were randomly assigned to receive one of three high-fat (55.2% of total calories), low-carbohydrate diets containing isocaloric amounts of lipids for 4 days. The control diet was enriched with linoleic acid, whereas the two test diets were low in linoleic acid and enriched with either 5 mole % eicosapentaenoic acid alone or in combination with 5 mole % gamma-linolenic acid. Alveolar macrophages were then procured to assess phospholipid fatty acid composition, eicosanoid synthesis after stimulation with endotoxin, superoxide formation and phagocytosis by flow cytometry, and killing of Staphylococcus aureus Alveolar macrophage levels of arachidonic acid were significantly (p < .01) lower and levels of eicosapentaenoic and dihomo-gamma-linolenic acids were higher after feeding the eicosapentaenoic and gamma-linolenic acid diet vs. the linoleic acid diet. Ratios of thromboxane B2,/B3, leukotriene B4/B5, and prostaglandin E2/E1 were reduced in the macrophages from rats given either the eicosapentaenoic acid or eicosapentaenoic acid with gamma-linolenic acid diet compared with ratios from rats given the linoleic acid diet. Macrophages from rats given the eicosapentaenoic with gamma-linolenic acid diet released 35% or 24% more prostaglandin E1 than macrophages from rats given either the linoleic acid or the eicosapentaenoic acid diet, respectively. Macrophage superoxide generation, phagocytosis of opsonized zymosan, and killing of S. aureus were similar irrespective of dietary treatment. Short-term enteral feeding with an eicosapentaenoic acid-enriched or eicosapentaenoic with gamma-linolenic acid-enriched diet rapidly modulated the fatty acid composition of alveolar macrophage phospholipids, promoted a shift toward formation of less inflammatory eicosanoids by stimulated macrophages, but did not impair alveolar macrophage bactericidal function relative to responses observed after feeding a linoleic acid diet.

Measuring bovine gamma delta T cell function at the site of Mycobacterium bovis infection

USDA-ARS?s Scientific Manuscript database

The causative agent of tuberculosis (TB) in cattle is Mycobacterium bovis. The characteristic lesions of bovine TB are well-organized pulmonary granulomas. Gamma delta T cells are a unique subset of nonconventional T cells that play major roles in both the innate and adaptive arms of the immune sys...

Functional genomics analysis of big data identifies novel peroxisome proliferator–activated receptor gamma target single nucleotide polymorphisms showing association with cardiometabolic outcomes

USDA-ARS?s Scientific Manuscript database

Background Cardiovascular disease and type 2 diabetes mellitus represent overlapping diseases where a large portion of the variation attributable to genetics remains unexplained. An important player in their pathogenesis is peroxisome proliferator–activated receptor gamma (PPARgamma) that is involve...

Smooth Optical Self-similar Emission of Gamma-Ray Bursts

NASA Astrophysics Data System (ADS)

Lipunov, Vladimir; Simakov, Sergey; Gorbovskoy, Evgeny; Vlasenko, Daniil

2017-08-01

We offer a new type of calibration for gamma-ray bursts (GRB), in which some class of GRB can be marked and share a common behavior. We name this behavior Smooth Optical Self-similar Emission (SOS-similar Emission) and identify this subclasses of GRBs with optical light curves described by a universal scaling function.

Deletion mutagenesis identifies a haploinsufficient role for gamma-zein in opaque-2 endosperm modification

USDA-ARS?s Scientific Manuscript database

Quality Protein Maize (QPM) is a hard kernel variant of the high-lysine mutant, opaque-2. Using gamma irradiation, we created opaque QPM variants to identify opaque-2 modifier genes and to investigate deletion mutagenesis combined with Illumina sequencing as a maize functional genomics tool. A K0326...

Effect of gamma irradiation on physicochemical properties of stored pigeon pea (Cajanus cajan) flour

PubMed Central

Bamidele, Oluwaseun P; Akanbi, Charles T

2013-01-01

The effect of gamma irradiation at various doses (5, 10, 15, 20 kGy) was observed on pigeon pea flour stored for 3 months on proximate composition, functional properties, and peroxide value. Sensory evaluation was also carried out on bean cake (moinmoin) made from nonirradiated and irradiated pigeon pea flour. The results showed that stored gamma-irradiated samples had significantly lower (P < 0.05) value of protein and little or no effect on moisture content. There were slight decreases in crude fiber and ash content of the irradiated samples compared with the control sample. The result of functional properties of the irradiated flours showed slight increase in water absorption capacity, swelling capacity and bulk density. The peroxide value of crude oil increased significantly with dose increases for the period of storage. The sensory evaluation of moinmoin samples prepared from irradiated pigeon pea flour showed no significant difference from the moinmoin sample prepared from nonirradiated flour. It can be concluded that gamma irradiation can extend the shelf life of pigeon pea flour. PMID:24804044

Effect of gamma irradiation on physicochemical properties of stored pigeon pea (Cajanus cajan) flour.

PubMed

Bamidele, Oluwaseun P; Akanbi, Charles T

2013-09-01

The effect of gamma irradiation at various doses (5, 10, 15, 20 kGy) was observed on pigeon pea flour stored for 3 months on proximate composition, functional properties, and peroxide value. Sensory evaluation was also carried out on bean cake (moinmoin) made from nonirradiated and irradiated pigeon pea flour. The results showed that stored gamma-irradiated samples had significantly lower (P < 0.05) value of protein and little or no effect on moisture content. There were slight decreases in crude fiber and ash content of the irradiated samples compared with the control sample. The result of functional properties of the irradiated flours showed slight increase in water absorption capacity, swelling capacity and bulk density. The peroxide value of crude oil increased significantly with dose increases for the period of storage. The sensory evaluation of moinmoin samples prepared from irradiated pigeon pea flour showed no significant difference from the moinmoin sample prepared from nonirradiated flour. It can be concluded that gamma irradiation can extend the shelf life of pigeon pea flour.

Plasmodium falciparum erythrocyte membrane protein-1 specifically suppresses early production of host interferon-gamma.

PubMed

D'Ombrain, Marthe C; Voss, Till S; Maier, Alexander G; Pearce, J Andrew; Hansen, Diana S; Cowman, Alan F; Schofield, Louis

2007-08-16

Plasmodium falciparum erythrocyte membrane protein-1 (PfEMP-1) is a variable antigen expressed by P. falciparum, the malarial parasite. PfEMP-1, present on the surface of infected host erythrocytes, mediates erythrocyte binding to vascular endothelium, enabling the parasite to avoid splenic clearance. In addition, PfEMP-1 is proposed to regulate host immune responses via interactions with the CD36 receptor on antigen-presenting cells. We investigated the immunoregulatory function of PfEMP-1 by comparing host cell responses to erythrocytes infected with either wild-type parasites or transgenic parasites lacking PfEMP-1. We showed that PfEMP-1 suppresses the production of the cytokine interferon-gamma by human peripheral blood mononuclear cells early after exposure to P. falciparum. Suppression of this rapid proinflammatory response was CD36 independent and specific to interferon-gamma production by gammadelta-T, NK, and alphabeta-T cells. These data demonstrate a parasite strategy for downregulating the proinflammatory interferon-gamma response and further establish transgenic parasites lacking PfEMP-1 as powerful tools for elucidating PfEMP-1 functions.

Dopamine Modulates Delta-Gamma Phase-Amplitude Coupling in the Prefrontal Cortex of Behaving Rats.

PubMed

Andino-Pavlovsky, Victoria; Souza, Annie C; Scheffer-Teixeira, Robson; Tort, Adriano B L; Etchenique, Roberto; Ribeiro, Sidarta

2017-01-01

Dopamine release and phase-amplitude cross-frequency coupling (CFC) have independently been implicated in prefrontal cortex (PFC) functioning. To causally investigate whether dopamine release affects phase-amplitude comodulation between different frequencies in local field potentials (LFP) recorded from the medial PFC (mPFC) of behaving rats, we used RuBiDopa, a light-sensitive caged compound that releases the neurotransmitter dopamine when irradiated with visible light. LFP power did not change in any frequency band after the application of light-uncaged dopamine, but significantly strengthened phase-amplitude comodulation between delta and gamma oscillations. Saline did not exert significant changes, while injections of dopamine and RuBiDopa produced a slow increase in comodulation for several minutes after the injection. The results show that dopamine release in the medial PFC shifts phase-amplitude comodulation from theta-gamma to delta-gamma. Although being preliminary results due to the limitation of the low number of animals present in this study, our findings suggest that dopamine-mediated modification of the frequencies involved in comodulation could be a mechanism by which this neurotransmitter regulates functioning in mPFC.

A new gamma ray imaging diagnostic for runaway electron studies at DIII-D

NASA Astrophysics Data System (ADS)

Cooper, C. M.; Pace, D. C.; Eidietis, N. W.; Paz-Soldan, C.; Commaux, N.; Shiraki, D.; Hollmann, E. M.; Moyer, R. A.; Risov, V.

2015-11-01

A new Gamma Ray Imager (GRI) is developed to probe the electron distribution function with 2D spatial resolution during runaway electron (RE) experiments at DIII-D. The diagnostic is sensitive to 0.5 - 50 MeV gamma rays, allowing characterization of the RE distribution function evolution during RE dissipation from pellet injection. The GRI consists of a lead ``pinhole camera'' mounted on the midplane with 11x11 counter-current tangential chords 20 cm wide that span the vessel. Up to 30 bismuth germanate (BGO) scintillation detectors capture RE Bremsstrahlung radiation. Detectors operate in current saturation mode at 10 MHz, or the flux is attenuated for Pulse Height Analysis (PHA) capable of discriminating up to ~10k pulses per second. Digital signal processing routines combining shaping filters are performed during PHA to reject noise and record gamma ray energy. The GRI setup and PHA algorithms will be described and initial data from experiments will be presented. Work supported by the US DOE under DE-AC05-00OR22725, DE-FG02-07ER54917 & DE-FC02-04ER54698.

Derivatives of logarithmic stationary distributions for policy gradient reinforcement learning.

PubMed

Morimura, Tetsuro; Uchibe, Eiji; Yoshimoto, Junichiro; Peters, Jan; Doya, Kenji

2010-02-01

Most conventional policy gradient reinforcement learning (PGRL) algorithms neglect (or do not explicitly make use of) a term in the average reward gradient with respect to the policy parameter. That term involves the derivative of the stationary state distribution that corresponds to the sensitivity of its distribution to changes in the policy parameter. Although the bias introduced by this omission can be reduced by setting the forgetting rate gamma for the value functions close to 1, these algorithms do not permit gamma to be set exactly at gamma = 1. In this article, we propose a method for estimating the log stationary state distribution derivative (LSD) as a useful form of the derivative of the stationary state distribution through backward Markov chain formulation and a temporal difference learning framework. A new policy gradient (PG) framework with an LSD is also proposed, in which the average reward gradient can be estimated by setting gamma = 0, so it becomes unnecessary to learn the value functions. We also test the performance of the proposed algorithms using simple benchmark tasks and show that these can improve the performances of existing PG methods.

Experienced Mindfulness Meditators Exhibit Higher Parietal-Occipital EEG Gamma Activity during NREM Sleep

PubMed Central

Ferrarelli, Fabio; Smith, Richard; Dentico, Daniela; Riedner, Brady A.; Zennig, Corinna; Benca, Ruth M.; Lutz, Antoine; Davidson, Richard J.; Tononi, Giulio

2013-01-01

Over the past several years meditation practice has gained increasing attention as a non-pharmacological intervention to provide health related benefits, from promoting general wellness to alleviating the symptoms of a variety of medical conditions. However, the effects of meditation training on brain activity still need to be fully characterized. Sleep provides a unique approach to explore the meditation-related plastic changes in brain function. In this study we performed sleep high-density electroencephalographic (hdEEG) recordings in long-term meditators (LTM) of Buddhist meditation practices (approximately 8700 mean hours of life practice) and meditation naive individuals. We found that LTM had increased parietal-occipital EEG gamma power during NREM sleep. This increase was specific for the gamma range (25–40 Hz), was not related to the level of spontaneous arousal during NREM and was positively correlated with the length of lifetime daily meditation practice. Altogether, these findings indicate that meditation practice produces measurable changes in spontaneous brain activity, and suggest that EEG gamma activity during sleep represents a sensitive measure of the long-lasting, plastic effects of meditative training on brain function. PMID:24015304

Assessment of Gamma-Ray Spectra Analysis Method Utilizing the Fireworks Algorithm for various Error Measures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alamaniotis, Miltiadis; Tsoukalas, Lefteri H.

2018-01-01

Significant role in enhancing nuclear nonproliferation plays the analysis of obtained data and the inference of the presence or not of special nuclear materials in them. Among various types of measurements, gamma-ray spectra is the widest used type of data utilized for analysis in nonproliferation. In this chapter, a method that employs the fireworks algorithm (FWA) for analyzing gamma-ray spectra aiming at detecting gamma signatures is presented. In particular FWA is utilized to fit a set of known signatures to a measured spectrum by optimizing an objective function, with non-zero coefficients expressing the detected signatures. FWA is tested on amore » set of experimentally obtained measurements and various objective functions -MSE, RMSE, Theil-2, MAE, MAPE, MAP- with results exhibiting its potential in providing high accuracy and high precision of detected signatures. Furthermore, FWA is benchmarked against genetic algorithms, and multiple linear regression with results exhibiting its superiority over the rest tested algorithms with respect to precision for MAE, MAPE and MAP measures.« less

Dopamine Modulates Delta-Gamma Phase-Amplitude Coupling in the Prefrontal Cortex of Behaving Rats

PubMed Central

Andino-Pavlovsky, Victoria; Souza, Annie C.; Scheffer-Teixeira, Robson; Tort, Adriano B. L.; Etchenique, Roberto; Ribeiro, Sidarta

2017-01-01

Dopamine release and phase-amplitude cross-frequency coupling (CFC) have independently been implicated in prefrontal cortex (PFC) functioning. To causally investigate whether dopamine release affects phase-amplitude comodulation between different frequencies in local field potentials (LFP) recorded from the medial PFC (mPFC) of behaving rats, we used RuBiDopa, a light-sensitive caged compound that releases the neurotransmitter dopamine when irradiated with visible light. LFP power did not change in any frequency band after the application of light-uncaged dopamine, but significantly strengthened phase-amplitude comodulation between delta and gamma oscillations. Saline did not exert significant changes, while injections of dopamine and RuBiDopa produced a slow increase in comodulation for several minutes after the injection. The results show that dopamine release in the medial PFC shifts phase-amplitude comodulation from theta-gamma to delta-gamma. Although being preliminary results due to the limitation of the low number of animals present in this study, our findings suggest that dopamine-mediated modification of the frequencies involved in comodulation could be a mechanism by which this neurotransmitter regulates functioning in mPFC. PMID:28536507

Perforin and gamma interferon expression are required for CD4+ and CD8+ T-cell-dependent protective immunity against a human parasite, Trypanosoma cruzi, elicited by heterologous plasmid DNA prime-recombinant adenovirus 5 boost vaccination.

PubMed

de Alencar, Bruna C G; Persechini, Pedro M; Haolla, Filipe A; de Oliveira, Gabriel; Silverio, Jaline C; Lannes-Vieira, Joseli; Machado, Alexandre V; Gazzinelli, Ricardo T; Bruna-Romero, Oscar; Rodrigues, Mauricio M

2009-10-01

A heterologous prime-boost strategy using plasmid DNA, followed by replication-defective recombinant adenovirus 5, is being proposed as a powerful way to elicit CD4(+) and CD8(+) T-cell-mediated protective immunity against intracellular pathogens. We confirmed this concept and furthered existing research by providing evidence that the heterologous prime-boost regimen using the gene encoding amastigote surface protein 2 elicited CD4(+) and CD8(+) T-cell-mediated protective immunity (reduction of acute parasitemia and prolonged survival) against experimental infection with Trypanosoma cruzi. Protective immunity correlated with the presence of in vivo antigen-specific cytotoxic activity prior to challenge. Based on this, our second goal was to determine the outcome of infection after heterologous prime-boost immunization of perforin-deficient mice. These mice were highly susceptible to infection. A detailed analysis of the cell-mediated immune responses in immunized perforin-deficient mice showed an impaired gamma interferon (IFN-gamma) secretion by immune spleen cells upon restimulation in vitro with soluble recombinant antigen. In spite of a normal numeric expansion, specific CD8(+) T cells presented several functional defects detected in vivo (cytotoxicity) and in vitro (simultaneous expression of CD107a/IFN-gamma or IFN-gamma/tumor necrosis factor alpha) paralleled by a decreased expression of CD44 and KLRG-1. Our final goal was to determine the importance of IFN-gamma in the presence of highly cytotoxic T cells. Vaccinated IFN-gamma-deficient mice developed highly cytotoxic cells but failed to develop any protective immunity. Our study thus demonstrated a role for perforin and IFN-gamma in a number of T-cell-mediated effector functions and in the antiparasitic immunity generated by a heterologous plasmid DNA prime-adenovirus boost vaccination strategy.

The spatial resolution of a rotating gamma camera tomographic facility.

PubMed

Webb, S; Flower, M A; Ott, R J; Leach, M O; Inamdar, R

1983-12-01

An important feature determining the spatial resolution in transverse sections reconstructed by convolution and back-projection is the frequency filter corresponding to the convolution kernel. Equations have been derived giving the theoretical spatial resolution, for a perfect detector and noise-free data, using four filter functions. Experiments have shown that physical constraints will always limit the resolution that can be achieved with a given system. The experiments indicate that the region of the frequency spectrum between KN/2 and KN where KN is the Nyquist frequency does not contribute significantly to resolution. In order to investigate the physical effect of these filter functions, the spatial resolution of reconstructed images obtained with a GE 400T rotating gamma camera has been measured. The results obtained serve as an aid to choosing appropriate reconstruction filters for use with a rotating gamma camera system.

Gravitational lensing, time delay, and gamma-ray bursts

NASA Technical Reports Server (NTRS)

Mao, Shude

1992-01-01

The probability distributions of time delay in gravitational lensing by point masses and isolated galaxies (modeled as singular isothermal spheres) are studied. For point lenses (all with the same mass) the probability distribution is broad, and with a peak at delta(t) of about 50 S; for singular isothermal spheres, the probability distribution is a rapidly decreasing function with increasing time delay, with a median delta(t) equals about 1/h month, and its behavior depends sensitively on the luminosity function of galaxies. The present simplified calculation is particularly relevant to the gamma-ray bursts if they are of cosmological origin. The frequency of 'recurrent' bursts due to gravitational lensing by galaxies is probably between 0.05 and 0.4 percent. Gravitational lensing can be used as a test of the cosmological origin of gamma-ray bursts.

Accelerator test of the coded aperture mask technique for gamma-ray astronomy

NASA Technical Reports Server (NTRS)

Jenkins, T. L.; Frye, G. M., Jr.; Owens, A.; Carter, J. N.; Ramsden, D.

1982-01-01

A prototype gamma-ray telescope employing the coded aperture mask technique has been constructed and its response to a point source of 20 MeV gamma-rays has been measured. The point spread function is approximately a Gaussian with a standard deviation of 12 arc minutes. This resolution is consistent with the cell size of the mask used and the spatial resolution of the detector. In the context of the present experiment, the error radius of the source position (90 percent confidence level) is 6.1 arc minutes.

SU-C-204-01: A Fast Analytical Approach for Prompt Gamma and PET Predictions in a TPS for Proton Range Verification

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kroniger, K; Herzog, M; Landry, G

2015-06-15

Purpose: We describe and demonstrate a fast analytical tool for prompt-gamma emission prediction based on filter functions applied on the depth dose profile. We present the implementation in a treatment planning system (TPS) of the same algorithm for positron emitter distributions. Methods: The prediction of the desired observable is based on the convolution of filter functions with the depth dose profile. For both prompt-gammas and positron emitters, the results of Monte Carlo simulations (MC) are compared with those of the analytical tool. For prompt-gamma emission from inelastic proton-induced reactions, homogeneous and inhomogeneous phantoms alongside with patient data are used asmore » irradiation targets of mono-energetic proton pencil beams. The accuracy of the tool is assessed in terms of the shape of the analytically calculated depth profiles and their absolute yields, compared to MC. For the positron emitters, the method is implemented in a research RayStation TPS and compared to MC predictions. Digital phantoms and patient data are used and positron emitter spatial density distributions are analyzed. Results: Calculated prompt-gamma profiles agree with MC within 3 % in terms of absolute yield and reproduce the correct shape. Based on an arbitrary reference material and by means of 6 filter functions (one per chemical element), profiles in any other material composed of those elements can be predicted. The TPS implemented algorithm is accurate enough to enable, via the analytically calculated positron emitters profiles, detection of range differences between the TPS and MC with errors of the order of 1–2 mm. Conclusion: The proposed analytical method predicts prompt-gamma and positron emitter profiles which generally agree with the distributions obtained by a full MC. The implementation of the tool in a TPS shows that reliable profiles can be obtained directly from the dose calculated by the TPS, without the need of full MC simulation.« less

Comparison of effect of gamma ray irradiation on wild-type and N-terminal mutants of αA-crystallin.

PubMed

Ramkumar, Srinivasagan; Fujii, Noriko; Fujii, Norihiko; Thankappan, Bency; Sakaue, Hiroaki; Ingu, Kim; Natarajaseenivasan, Kalimuthusamy; Anbarasu, Kumarasamy

2014-01-01

To study the comparative structural and functional changes between wild-type (wt) and N-terminal congenital cataract causing αA-crystallin mutants (R12C, R21L, R49C, and R54C) upon exposure to different dosages of gamma rays. Alpha A crystallin N-terminal mutants were created with the site-directed mutagenesis method. The recombinantly overexpressed and purified wt and mutant proteins were used for further studies. A (60)Co source was used to generate gamma rays to irradiate wild and mutant proteins at dosages of 0.5, 1.0, and 2.0 kGy. The biophysical property of the gamma irradiated (GI) and non-gamma irradiated (NGI) αA-crystallin wt and N-terminal mutants were determined. Oligomeric size was determined by size exclusion high-performance liquid chromatography (HPLC), the secondary structure with circular dichroism (CD) spectrometry, conformation of proteins with surface hydrophobicity, and the functional characterization were determined regarding chaperone activity using the alcohol dehydrogenase (ADH) aggregation assay. αA-crystallin N-terminal mutants formed high molecular weight (HMW) cross-linked products as well as aggregates when exposed to GI compared to the NGI wt counterparts. Furthermore, all mutants exhibited changed β-sheet and random coil structure. The GI mutants demonstrated decreased surface hydrophobicity when compared to αA-crystallin wt at 0, 1.0, and 1.5 kGy; however, at 2.0 kGy a drastic increase in hydrophobicity was observed only in the mutant R54C, not the wt. In contrast, chaperone activity toward ADH was gradually elevated at the minimum level in all GI mutants, and significant elevation was observed in the R12C mutant. Our findings suggest that the N-terminal mutants of αA-crystallin are structurally and functionally more sensitive to GI when compared to their NGI counterparts and wt. Protein oxidation as a result of gamma irradiation drives the protein to cross-link and aggregate culminating in cataract formation.

TU-A-12A-01: Consistency of Lung Expansion and Contraction During Respiration: Implications for Quantitative Imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patton, T; Du, K; Bayouth, J

Purpose: Four-dimensional computed tomography (4DCT) can be used to evaluate longitudinal changes in pulmonary function. The sensitivity of such measurements to identify function change may be improved with reproducible breathing patterns. The purpose of this study was to determine if inhale was more consistent than exhale, i.e., lung expansion during inhalation compared to lung contraction during exhalation. Methods: Repeat 4DCT image data acquired within a short time interval from 8 patients. Using a tissue volume preserving deformable image registration algorithm, Jacobian ventilation maps in two scanning sessions were computed and compared on the same coordinate for reproducibility analysis. Equivalent lungmore » volumes (ELV) were used for 5 subjects and equivalent title volumes (ETV) for the 3 subjects who experienced a baseline shift between scans. In addition, gamma pass rate was calculated from a modified gamma index evaluation between two ventilation maps, using acceptance criterions of 2mm distance-to-agreement and 5% ventilation difference. The gamma pass rates were then compared using paired t-test to determine if there was a significant difference. Results: Inhalation was more reproducible than exhalation. In the 5 ELV subjects 78.5% of the lung voxels met the gamma criteria for expansion during inhalation when comparing the two scans, while significantly fewer (70.9% of the lung voxels) met the gamma criteria for contraction during exhalation (p = .027). In the 8 total subjects analyzed the average gamma pass rate for expansion during inhalation was 75.2% while for contraction during exhalation it was 70.3%; which trended towards significant (p = .064). Conclusion: This work implies inhalation is more reproducible than exhalation, when equivalent respiratory volumes are considered. The reason for this difference is unknown. Longitudinal investigation of pulmonary function change based on inhalation images appears appropriate for Jacobian-based measure of lung tissue expansion. NIH Grant: R01 CA166703.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alimirah, Fatouma; Peng, Xinjian; Yuan, Liang

Heterodimerization and cross-talk between nuclear hormone receptors often occurs. For example, estrogen receptor alpha (ER{alpha}) physically binds to peroxisome proliferator-activated receptor gamma (PPAR{gamma}) and inhibits its transcriptional activity. The interaction between PPAR{gamma} and the vitamin D receptor (VDR) however, is unknown. Here, we elucidate the molecular mechanisms linking PPAR{gamma} and VDR signaling, and for the first time we show that PPAR{gamma} physically associates with VDR in human breast cancer cells. We found that overexpression of PPAR{gamma} decreased 1{alpha},25-dihydroxyvitamin D{sub 3} (1,25D{sub 3}) mediated transcriptional activity of the vitamin D target gene, CYP24A1, by 49% and the activity of VDRE-luc, amore » vitamin D responsive reporter, by 75% in T47D human breast cancer cells. Deletion mutation experiments illustrated that helices 1 and 4 of PPAR{gamma}'s hinge and ligand binding domains, respectively, governed this suppressive function. Additionally, abrogation of PPAR{gamma}'s AF2 domain attenuated its repressive action on 1,25D{sub 3} transactivation, indicating that this domain is integral in inhibiting VDR signaling. PPAR{gamma} was also found to compete with VDR for their binding partner retinoid X receptor alpha (RXR{alpha}). Overexpression of RXR{alpha} blocked PPAR{gamma}'s suppressive effect on 1,25D{sub 3} action, enhancing VDR signaling. In conclusion, these observations uncover molecular mechanisms connecting the PPAR{gamma} and VDR pathways. -- Highlights: PPAR{gamma}'s role on 1{alpha},25-dihydroxyvitamin D{sub 3} transcriptional activity is examined. Black-Right-Pointing-Pointer PPAR{gamma} physically binds to VDR and inhibits 1{alpha},25-dihydroxyvitamin D{sub 3} action. Black-Right-Pointing-Pointer PPAR{gamma}'s hinge and ligand binding domains are important for this inhibitory effect. Black-Right-Pointing-Pointer PPAR{gamma} competes with VDR for the availability of their binding partner, RXR{alpha}.« less

A bivariate gamma probability distribution with application to gust modeling. [for the ascent flight of the space shuttle

NASA Technical Reports Server (NTRS)

Smith, O. E.; Adelfang, S. I.; Tubbs, J. D.

1982-01-01

A five-parameter gamma distribution (BGD) having two shape parameters, two location parameters, and a correlation parameter is investigated. This general BGD is expressed as a double series and as a single series of the modified Bessel function. It reduces to the known special case for equal shape parameters. Practical functions for computer evaluations for the general BGD and for special cases are presented. Applications to wind gust modeling for the ascent flight of the space shuttle are illustrated.

Early irradiation syndrome. A study of the functional changes in the rabbit following whole-body $gamma$ exposure at sublethal doses (in French)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dufour, R.; Collignon, Y.; Vincent, F.

1975-05-01

A method of simultaneous observation of several physiological functions was developed in the unanaesthetized rabbit. Arterial blood pressure, local brain circulation, internal body temperature and arterial blodd acido-basic balance were thus followed before, during and after $gamma$-irradiation. There appeared two periods in the development of this early syndrome: they were related to two processes, a central one, mainly of sympathetic origin was hardly sensitive to the dose, the other is dose-dependent. (FR)

Neutron and gamma dose and spectra measurements on the Little Boy replica

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoots, S.; Wadsworth, D.

1984-06-01

The radiation-measurement team of the Weapons Engineering Division at Lawrence Livermore National Laboratory (LLNL) measured neutron and gamma dose and spectra on the Little Boy replica at Los Alamos National Laboratory (LANL) in April 1983. This assembly is a replica of the gun-type atomic bomb exploded over Hiroshima in 1945. These measurements support the National Academy of Sciences Program to reassess the radiation doses due to atomic bomb explosions in Japan. Specifically, the following types of information were important: neutron spectra as a function of geometry, gamma to neutron dose ratios out to 1.5 km, and neutron attenuation in themore » atmosphere. We measured neutron and gamma dose/fission from close-in to a kilometer out, and neutron and gamma spectra at 90 and 30/sup 0/ close-in. This paper describes these measurements and the results. 12 references, 13 figures, 5 tables.« less

Study of gamma detection capabilities of the REWARD mobile spectroscopic system

NASA Astrophysics Data System (ADS)

Balbuena, J. P.; Baptista, M.; Barros, S.; Dambacher, M.; Disch, C.; Fiederle, M.; Kuehn, S.; Parzefall, U.

2017-07-01

REWARD is a novel mobile spectroscopic radiation detector system for Homeland Security applications. The system integrates gamma and neutron detection equipped with wireless communication. A comprehensive simulation study on its gamma detection capabilities in different radioactive scenarios is presented in this work. The gamma detection unit consists of a precise energy resolution system based on two stacked (Cd,Zn)Te sensors working in coincidence sum mode. The volume of each of these CZT sensors is 1 cm3. The investigated energy windows used to determine the detection capabilities of the detector correspond to the gamma emissions from 137Cs and 60Co radioactive sources (662 keV and 1173/1333 keV respectively). Monte Carlo and Technology Computer-Aided Design (TCAD) simulations are combined to determine its sensing capabilities for different radiation sources and estimate the limits of detection of the sensing unit as a function of source activity for several shielding materials.

Learning alters theta amplitude, theta-gamma coupling and neuronal synchronization in inferotemporal cortex.

PubMed

Kendrick, Keith M; Zhan, Yang; Fischer, Hanno; Nicol, Alister U; Zhang, Xuejuan; Feng, Jianfeng

2011-06-09

How oscillatory brain rhythms alone, or in combination, influence cortical information processing to support learning has yet to be fully established. Local field potential and multi-unit neuronal activity recordings were made from 64-electrode arrays in the inferotemporal cortex of conscious sheep during and after visual discrimination learning of face or object pairs. A neural network model has been developed to simulate and aid functional interpretation of learning-evoked changes. Following learning the amplitude of theta (4-8 Hz), but not gamma (30-70 Hz) oscillations was increased, as was the ratio of theta to gamma. Over 75% of electrodes showed significant coupling between theta phase and gamma amplitude (theta-nested gamma). The strength of this coupling was also increased following learning and this was not simply a consequence of increased theta amplitude. Actual discrimination performance was significantly correlated with theta and theta-gamma coupling changes. Neuronal activity was phase-locked with theta but learning had no effect on firing rates or the magnitude or latencies of visual evoked potentials during stimuli. The neural network model developed showed that a combination of fast and slow inhibitory interneurons could generate theta-nested gamma. By increasing N-methyl-D-aspartate receptor sensitivity in the model similar changes were produced as in inferotemporal cortex after learning. The model showed that these changes could potentiate the firing of downstream neurons by a temporal desynchronization of excitatory neuron output without increasing the firing frequencies of the latter. This desynchronization effect was confirmed in IT neuronal activity following learning and its magnitude was correlated with discrimination performance. Face discrimination learning produces significant increases in both theta amplitude and the strength of theta-gamma coupling in the inferotemporal cortex which are correlated with behavioral performance. A network model which can reproduce these changes suggests that a key function of such learning-evoked alterations in theta and theta-nested gamma activity may be increased temporal desynchronization in neuronal firing leading to optimal timing of inputs to downstream neural networks potentiating their responses. In this way learning can produce potentiation in neural networks simply through altering the temporal pattern of their inputs.

Nonlinear evolution of magnetic flux ropes. 2: Finite beta plasma

NASA Technical Reports Server (NTRS)

Osherovich, V. A.; Farrugia, C. J.; Burlaga, L. F.

1995-01-01

In this second paper on the evolution of magnetic flux ropes we study the effects of gas pressure. We assume that the energy transport is described by a polytropic relationship and reduce the set of ideal MHD equations to a single, second-order, nonlinear, ordinary differential equation for the evolution function. For this conservative system we obtain a first integral of motion. To analyze the possible motions, we use a mechanical analogue -- a one-dimensional, nonlinear oscillator. We find that the effective potential for such an oscillator depends on two parameters: the polytropic index gamma and a dimensionless quantity kappa the latter being a function of the plasma beta, the strength of the azimuthal magnetic field relative to the axial field of the flux rope, and gamma. Through a study of this effective potential we classify all possible modes of evolution of the system. In the main body of the paper, we focus on magnetic flux ropes whose field and gas pressure increase steadily towards the symmetry axis. In this case, for gamma greater than 1 and all values of kappa, only oscillations are possible. For gamma less than 1, however, both oscillations and expansion are allowed. For gamma less than 1 and kappa below a critical value, the energy of the nonlinear oscillator determines whether the flux rope will oscillate or expand to infinity. For gamma less than 1 and kappa above critical, however, only expansion occurs. Thus by increasing kappa while keeping gamma fixed (less than 1), a phase transition occurs at kappa = kappa(sub critical) and the oscillatory mode disappears. We illustrate the above theoretical considerations by the example of a flux rope of constant field line twist evolving self-similarly. For this example, we present the full numerical MHD solution. In an appendix to the paper we catalogue all possible evolutions when (1) either the magnetic field or (2) the gas pressure decreases monotonically toward the axis. We find that in these cases critical conditions can occur for gamma greater than 1. While in most cases the flux rope collapses, there are notable exceptions when, for certain ranges of kappa and gamma, collapse may be averted.

Learning alters theta amplitude, theta-gamma coupling and neuronal synchronization in inferotemporal cortex

PubMed Central

2011-01-01

Background How oscillatory brain rhythms alone, or in combination, influence cortical information processing to support learning has yet to be fully established. Local field potential and multi-unit neuronal activity recordings were made from 64-electrode arrays in the inferotemporal cortex of conscious sheep during and after visual discrimination learning of face or object pairs. A neural network model has been developed to simulate and aid functional interpretation of learning-evoked changes. Results Following learning the amplitude of theta (4-8 Hz), but not gamma (30-70 Hz) oscillations was increased, as was the ratio of theta to gamma. Over 75% of electrodes showed significant coupling between theta phase and gamma amplitude (theta-nested gamma). The strength of this coupling was also increased following learning and this was not simply a consequence of increased theta amplitude. Actual discrimination performance was significantly correlated with theta and theta-gamma coupling changes. Neuronal activity was phase-locked with theta but learning had no effect on firing rates or the magnitude or latencies of visual evoked potentials during stimuli. The neural network model developed showed that a combination of fast and slow inhibitory interneurons could generate theta-nested gamma. By increasing N-methyl-D-aspartate receptor sensitivity in the model similar changes were produced as in inferotemporal cortex after learning. The model showed that these changes could potentiate the firing of downstream neurons by a temporal desynchronization of excitatory neuron output without increasing the firing frequencies of the latter. This desynchronization effect was confirmed in IT neuronal activity following learning and its magnitude was correlated with discrimination performance. Conclusions Face discrimination learning produces significant increases in both theta amplitude and the strength of theta-gamma coupling in the inferotemporal cortex which are correlated with behavioral performance. A network model which can reproduce these changes suggests that a key function of such learning-evoked alterations in theta and theta-nested gamma activity may be increased temporal desynchronization in neuronal firing leading to optimal timing of inputs to downstream neural networks potentiating their responses. In this way learning can produce potentiation in neural networks simply through altering the temporal pattern of their inputs. PMID:21658251

The Influence of Tungsten on the Chemical Composition of a Temporally Evolving Nanostructure of a Model Ni-Al-Cr Superalloy

NASA Technical Reports Server (NTRS)

Sudbrack, Chantal K.; Isheim, Dieter; Noebe, Ronald D.; Jacobson, Nathan S.; Seidman, David N.

2004-01-01

The influence of W on the temporal evolution of gamma' precipitation toward equilibrium in a model Ni-Al-Cr alloy is investigated by three-dimensional atom-probe (3DAP) microscopy and transmission electron microscopy (TEM). We report on the alloys Ni-10 Al-8.5 Cr (at.%) and Ni-10 Al-8.5 Cr-2 W (at.%), which were aged isothermally in the gamma + gamma' two-phase field at 1073 K, for times ranging from 0.25 to 264 h. Spheroidal-shaped gamma' precipitates, 5-15 nm diameter, form during quenching from above the solvus temperature in both alloys at a high number density (approx. 10(exp 23/cu m). As gamma' precipitates grow with aging at 1073 K, a transition from spheriodal- to cuboidal-shaped precipitates is observed in both alloys. The elemental partitioning and spatially resolved concentration profiles across the gamma' precipitates are obtained as a function of aging time from three-dimensional atom-by-atom reconstructions. Proximity histogram concentration profiles of the quaternary alloy demonstrate that W concentration gradients exist in gamma' precipitates in the as-quenched and 0.25-h aging states, which disappear after 1 h of aging. The diffusion coefficient of W in gamma' is estimated to be 6.2 x 10(exp -20) sq m/s at 1073 K. The W addition decreases the coarsening rate constant, and leads to stronger partitioning of Al to gamma' and Cr to gamma.

Featured Article: Dexamethasone and rosiglitazone are sufficient and necessary for producing functional adipocytes from mesenchymal stem cells

PubMed Central

Ezquer, Fernando; Espinosa, Maximiliano; Arango-Rodriguez, Martha; Puebla, Carlos; Sobrevia, Luis; Conget, Paulette

2015-01-01

The final product of adipogenesis is a functional adipocyte. This mature cell acquires the necessary machinery for lipid metabolism, loses its proliferation potential, increases its insulin sensitivity, and secretes adipokines. Multipotent mesechymal stromal cells have been recognized as a source of adipocytes both in vivo and in vitro. The in vitro adipogenic differentiation of human MSC (hMSC) has been induced up to now by using a complex stimulus which includes dexamethasone, 3-isobutyl-1-methylxanthine, indomethacin, and insulin (a classical cocktail) and evaluated according to morphological changes. The present work was aimed at demonstrating that the simultaneous activation of dexamethasone’s canonical signaling pathways, through the glucocorticoid receptor and CCAAT-enhancer-binding proteins (C/EBPs) and rosiglitazone through peroxisome proliferator-activated receptor gamma (PPAR-gamma) is sufficient yet necessary for inducing hMSC adipogenic differentiation. It was also ascertained that hMSC exposed just to dexamethasone and rosiglitazone (D&R) differentiated into cells which accumulated neutral lipid droplets, expressed C/EBP-alpha, PPAR-gamma, aP2, lipoprotein lipase, acyl-CoA synthetase, phosphoenolpyruvate carboxykinase, adiponectin, and leptin genes but did not proliferate. Glucose uptake was dose dependent on insulin stimulus and high levels of adipokines were secreted (i.e. displaying not only the morphology but also expressing mature adipocytes’ specific genes and functional characteristics). This work has demonstrated that (i) the activating C/EBPs and PPAR-gamma signaling pathways were sufficient to induce adipogenic differentiation from hMSC, (ii) D&R producing functional adipocytes from hMSC, (iii) D&R induce adipogenic differentiation from mammalian MSC (including those which are refractory to classical adipogenic differentiation stimuli). D&R would thus seem to be a useful tool for MSC characterization, studying adipogenesis pathways and producing functional adipocytes. PMID:25595190

Reduced gamma frequency in the medial frontal cortex of aged rats during behavior and rest: implications for age-related behavioral slowing.

PubMed

Insel, Nathan; Patron, Lilian A; Hoang, Lan T; Nematollahi, Saman; Schimanski, Lesley A; Lipa, Peter; Barnes, Carol A

2012-11-14

Age-related cognitive and behavioral slowing may be caused by changes in the speed of neural signaling or by changes in the number of signaling steps necessary to achieve a given function. In the mammalian cortex, neural communication is organized by a 30-100 Hz "gamma" oscillation. There is a putative link between the gamma frequency and the speed of processing in a neural network: the dynamics of pyramidal neuron membrane time constants suggest that synaptic integration is framed by the gamma cycle, and pharmacological slowing of gamma also slows reaction times on behavioral tasks. The present experiments identify reductions in a robust 40-70 Hz gamma oscillation in the aged rat medial frontal cortex. The reductions were observed in the form of local field potentials, later peaks in fast-spiking neuron autocorrelations, and delays in the spiking of inhibitory neurons following local excitatory signals. Gamma frequency did not vary with movement speed, but rats with slower gamma also moved more slowly. Gamma frequency age differences were not observed in hippocampus. Hippocampal CA1 fast-spiking neurons exhibited interspike intervals consistent with a fast (70-100 Hz) gamma frequency, a pattern maintained across theta phases and theta frequencies independent of fluctuations in the average firing rates of the neurons. We propose that an average lengthening of the cortical 15-25 ms gamma cycle is one factor contributing to age-related slowing and that future attempts to offset cognitive declines will find a target in the response of fast-spiking inhibitory neurons to excitatory inputs.

Study of Quantum Chaos in the Framework of Triaxial Rotator Models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Proskurins, J.; Bavrins, K.; Andrejevs, A.

2009-01-28

Dynamical quantum chaos criteria--a perturbed wave function entropy W({psi}{sub i}) and a fragmentation width {kappa}({phi}{sub k}) of basis states were studied in two cases of nuclear rigid triaxial rotator models. The first model is characterized by deformation angle {gamma} only, while the second model depends on both quadrupole deformation parameters ({beta},{gamma}). The degree of chaoticity has been determined in the studies of the dependence of criteria W({psi}{sub i}) and {kappa}({phi}{sub k}) from nuclear spin values up to I{<=}101 for model parameters {gamma} and ({beta},{gamma}) correspondingly. The transition from librational to rotational type energy spectra has been considered for both modelsmore » as well.« less

Comparison of degradation effects induced by gamma radiation and electron beam radiation in two cable jacketing materials

NASA Astrophysics Data System (ADS)

Bartoníček, B.; Plaček, V.; Hnát, V.

2007-05-01

The radiation degradation behavior of commercial low density polyethylene (LDPE) and ethylene-vinylacetate (EVA) cable materials has been investigated. The changes of mechanical properties, thermooxidative stability and density exhibit different radiation stability towards 60Co-gamma radiation and 160 keV electron beam radiation. This difference reflects much higher penetration of the gamma radiation through the polymeric material as a function of sample thickness. These results are discussed with respect to the role of beta radiation during design basis events in a nuclear power plants. In case when total accidental design basis event (DBE) dose (involving about 80% soft beta radiation) is simulated by 60Co-gamma radiation the conservatism is reached.

Querying databases of trajectories of differential equations 2: Index functions

NASA Technical Reports Server (NTRS)

Grossman, Robert

1991-01-01

Suppose that a large number of parameterized trajectories (gamma) of a dynamical system evolving in R sup N are stored in a database. Let eta is contained R sup N denote a parameterized path in Euclidean space, and let parallel to center dot parallel to denote a norm on the space of paths. A data structures and indices for trajectories are defined and algorithms are given to answer queries of the following forms: Query 1. Given a path eta, determine whether eta occurs as a subtrajectory of any trajectory gamma from the database. If so, return the trajectory; otherwise, return null. Query 2. Given a path eta, return the trajectory gamma from the database which minimizes the norm parallel to eta - gamma parallel.

Strength of Gamma Rhythm Depends on Normalization

PubMed Central

Ray, Supratim; Ni, Amy M.; Maunsell, John H. R.

2013-01-01

Neuronal assemblies often exhibit stimulus-induced rhythmic activity in the gamma range (30–80 Hz), whose magnitude depends on the attentional load. This has led to the suggestion that gamma rhythms form dynamic communication channels across cortical areas processing the features of behaviorally relevant stimuli. Recently, attention has been linked to a normalization mechanism, in which the response of a neuron is suppressed (normalized) by the overall activity of a large pool of neighboring neurons. In this model, attention increases the excitatory drive received by the neuron, which in turn also increases the strength of normalization, thereby changing the balance of excitation and inhibition. Recent studies have shown that gamma power also depends on such excitatory–inhibitory interactions. Could modulation in gamma power during an attention task be a reflection of the changes in the underlying excitation–inhibition interactions? By manipulating the normalization strength independent of attentional load in macaque monkeys, we show that gamma power increases with increasing normalization, even when the attentional load is fixed. Further, manipulations of attention that increase normalization increase gamma power, even when they decrease the firing rate. Thus, gamma rhythms could be a reflection of changes in the relative strengths of excitation and normalization rather than playing a functional role in communication or control. PMID:23393427

Comparative gene expression profiles induced by PPAR{gamma} and PPAR{alpha}/{gamma} agonists in rat hepatocytes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rogue, Alexandra; Universite de Rennes 1, 35065 Rennes Cedex; Biologie Servier, 45520 Gidy

2011-07-01

Species-differential toxic effects have been described with PPAR{alpha} and PPAR{gamma} agonists between rodent and human liver. PPAR{alpha} agonists (fibrates) are potent hypocholesterolemic agents in humans while they induce peroxisome proliferation and tumors in rodent liver. By contrast, PPAR{gamma} agonists (glitazones) and even dual PPAR{alpha}/{gamma} agonists (glitazars) have caused idiosyncratic hepatic and nonhepatic toxicities in human without evidence of any damage in rodent during preclinical studies. The mechanisms involved in such differences remain largely unknown. Several studies have identified the major target genes of PPAR{alpha} agonists in rodent liver while no comprehensive analysis has been performed on gene expression changes inducedmore » by PPAR{gamma} and dual PPAR{alpha}/{gamma} agonists. Here, we investigated transcriptomes of rat hepatocytes after 24 h treatment with two PPAR{gamma} (troglitazone and rosiglitazone) and two PPAR{alpha}/{gamma} (muraglitazar and tesaglitazar) agonists. Although, hierarchical clustering revealed a gene expression profile characteristic of each PPAR agonist class, only a limited number of genes was specifically deregulated by glitazars. Functional analyses showed that many genes known as PPAR{alpha} targets were also modulated by both PPAR{gamma} and PPAR{alpha}/{gamma} agonists and quantitative differences in gene expression profiles were observed between these two classes. Moreover, most major genes modulated in rat hepatocytes were also found to be deregulated in rat liver after tesaglitazar treatment. Taken altogether, these results support the conclusion that differential toxic effects of PPAR{alpha} and PPAR{gamma} agonists in rodent liver do not result from transcriptional deregulation of major PPAR target genes but rather from qualitative and/or quantitative differential responses of a small subset of genes.« less

Log-gamma linear-mixed effects models for multiple outcomes with application to a longitudinal glaucoma study

PubMed Central

Zhang, Peng; Luo, Dandan; Li, Pengfei; Sharpsten, Lucie; Medeiros, Felipe A.

2015-01-01

Glaucoma is a progressive disease due to damage in the optic nerve with associated functional losses. Although the relationship between structural and functional progression in glaucoma is well established, there is disagreement on how this association evolves over time. In addressing this issue, we propose a new class of non-Gaussian linear-mixed models to estimate the correlations among subject-specific effects in multivariate longitudinal studies with a skewed distribution of random effects, to be used in a study of glaucoma. This class provides an efficient estimation of subject-specific effects by modeling the skewed random effects through the log-gamma distribution. It also provides more reliable estimates of the correlations between the random effects. To validate the log-gamma assumption against the usual normality assumption of the random effects, we propose a lack-of-fit test using the profile likelihood function of the shape parameter. We apply this method to data from a prospective observation study, the Diagnostic Innovations in Glaucoma Study, to present a statistically significant association between structural and functional change rates that leads to a better understanding of the progression of glaucoma over time. PMID:26075565

Thermospheric nitric oxide from the ATLAS 1 and Spacelab 1 missions

NASA Technical Reports Server (NTRS)

Torr, Marsha R.; Torr, D. G.; Chang, T.; Richards, P.; Swift, W.; Li, N.

1995-01-01

Spectral and spatial images obtained with the Imaging Spectrometric Observatory on the ATLAS 1 and Spacelab 1 missions are used to study the ultraviolet emissions of nitric oxide in the thermosphere. By synthetically fitting the measured NO gamma bands, intensities are derived as a function of altitude and latitude. We find that the NO concentrations inferred from the ATLAS 1 measurements are higher than predicted by our thermospheric airglow model and tend to lie to the high side of a number of earlier measurements. By comparison with synthetic spectral fits, the shape of the NO gamma bands is used to derive temperature as a function of altitude. Using the simultaneous spectral and spatial imaging capability of the instrument, we present the first simultaneously acquired altitude images of NO gamma band temperature and intensity in the thermosphere. The lower thermospheric temperature images show structure as a function of altitude. The spatial imaging technique appears to be a viable means of obtaining temperatures in the middle and lower thermosphere, provided that good information is also obtained at the higher altitudes, as the contribution of the overlying, hotter NO is nonnegligible. By fitting both self-absorbed and nonabsorbed bands of the NO gamma system, we show that the self absorption effects are observable up to 200 km, although small above 150 km. The spectral resolution of the instrument (1.6 A) allows separation of the N(+)(S-5) doublet, and we show the contribution of this feature to the combination of the NO gamma (1, 0) band and the N(+)(S-5) doublet as a function of altitude (less than 10% below 200 km). Spectral images including the NO delta bands support previous findings that the fluorescence efficiency is much higher than that determined from laboratory measurements. The Spacelab 1 data indicate the presence of a significant population of hot NO in the vehicle environment of that early shuttle mission.

Energy Response Function of CALET Gamma Ray Burst Monitor

NASA Astrophysics Data System (ADS)

Yamada, Y.; Sakamoto, T.; Yoshida, A.; Calet Collaboration

2016-10-01

We will explain the development of the CGBM energy response function. We will also show the spectral analysis results of CGBM using our developed energy response function for simultaneously detected bright GRBs by other GRB detectors.

The control of inositol lipid hydrolysis.

PubMed

Katan, M

1996-01-01

Hydrolysis of PIP2 by specific PLC enzymes is involved in the regulation of different cellular processes by many extracellular signals. The need stringently to control this reaction is reflected by the fact that there are many PLC isozymes and multiple mechanisms linking these isozymes to various receptors. For two of the three PLC families found in mammalian cells (PLC beta and gamma), the components of the main regulatory pathways have been identified. PLC beta isozymes are regulated through G protein coupled receptors. Their activity is stimulated by interaction with alpha subunit from the Gq family and interaction with G protein beta gamma subunits. PLC gamma isozymes are regulated through receptor and non-receptor tyrosine kinases. The combination of SH2 dependent complex formation with phosphorylated tyrosine kinases and the subsequent phosphorylation of PLC gamma leads to stimulation of its activity. Although components that stimulate PLC beta and gamma isozymes have been identified, the molecular mechanism of stimulation remains largely unknown. Each signalling component operating within this general framework represents a family of related proteins. It is not clear what all the functional differences between members of the same family may be and to what extent they could determine specificity of individual signalling pathways. Similarly, it is not known to what extent alterations in PLC function/expression contribute to human pathologies. In the context of oncology, there is evidence for upregulation of PLC gamma in parallel with increased expression of the EGF receptor (Artega et al. 1991). However, it is not clear yet whether this is causally involved or a bystander effect.

Molecular dynamics study of thermodynamic scaling of the glass-transition dynamics in ionic liquids over wide temperature and pressure ranges.

PubMed

Habasaki, J; Casalini, R; Ngai, K L

2010-03-25

Experimentally, superpositioning of dynamic properties such as viscosity, relaxation times, or diffusion coefficients under different conditions of temperature T, pressure P, and volume V by the scaling variable TV(gamma) (where gamma is a material constant) has been reported as a general feature of many kinds of glass-forming materials. In the present work, molecular dynamics (MD) simulations have been performed to study the scaling of dynamics near the glass-transition regime of ionic liquids. Scaling in the simulated 1-ethyl-3-methylimidazolium nitrate (EMIM-NO(3)) system has been tested over wide ranges of temperatures and pressures. TV(gamma) scaling of the dynamics is well described by master curves with gamma = 4.0 +/- 0.2 and 3.8 +/- 0.2 for cation and anion, respectively. Structures and Coulombic terms of the corresponding states are found to be quite similar. The temperature and pressure dependence of the pair correlation function show similar trends and therefore can be superpositioned onto the master curve. Although the behaviors with gamma = 4 might be expected from the relation, gamma = n/3, for the dynamics with the soft-core-type potential U = epsilon(sigma/r)(n), with n = 12, pair potentials used in the MD simulation have a more complex form, and not all the repulsive terms can play their roles in the heterogeneous structures determined by ion-ion interactions. Scaling is related to the common part of effective potentials related to the pair correlation functions, including the many-body effect in real space.

Sensorimotor function is modulated by the serotonin receptor 1d, a novel marker for gamma motor neurons

PubMed Central

Enjin, Anders; Leão, Katarina E.; Mikulovic, Sanja; Le Merre, Pierre; Tourtellotte, Warren G.; Kullander, Klas

2012-01-01

Gamma motor neurons (MNs), the efferent component of the fusimotor system, regulate muscle spindle sensitivity. Muscle spindle sensory feedback is required for proprioception that includes sensing the relative position of neighboring body parts and appropriately adjust the employed strength in a movement. The lack of a single and specific genetic marker has long hampered functional and developmental studies of gamma MNs. Here we show that the serotonin receptor 1d (5-ht1d) is specifically expressed by gamma MNs and proprioceptive sensory neurons. Using mice expressing GFP driven by the 5-ht1d promotor, we performed whole-cell patch-clamp recordings of 5-ht1d∷GFP+ and 5-ht1d∷GFP− motor neurons from young mice. Hierarchal clustering analysis revealed that gamma MNs have distinct electrophysiological properties intermediate to fast-like and slow-like alpha MNs. Moreover, mice lacking 5-ht1d displayed lower monosynaptic reflex amplitudes suggesting a reduced response to sensory stimulation in motor neurons. Interestingly, adult 5-ht1d knockout mice also displayed improved coordination skills on a beam-walking task, implying that reduced activation of MNs by Ia afferents during provoked movement tasks could reduce undesired exaggerated muscle output. In summary, we show that 5-ht1d is a novel marker for gamma MNs and that the 5-ht1d receptor is important for the ability of proprioceptive circuits to receive and relay accurate sensory information in developing and mature spinal cord motor circuits. PMID:22273508

Gamma delta lymphocytes in endocrine autoimmunity: evidence of expansion in Graves' disease but not in type 1 diabetes.

PubMed Central

Roura-Mir, I C; Alcalde, L; Vargas, F; Tolosa, E; Obiols, G; Foz, M; Jaraquemada, D; Pujol-Borrell, R

1993-01-01

Endocrine autoimmune disorders are mediated by T cell-dependent responses to organ-specific antigens, but the mechanisms initiating the process remain unknown. Lymphocytes which use the gamma delta heterodimer as T cell receptor (TCR) for antigen constitute a distinct subset of T cells whose function remains elusive. In order to investigate their possible involvement in endocrine autoimmunity we have determined the proportion of gamma delta T cells in the peripheral blood of 23 patients with type 1 (insulin-dependent) diabetes mellitus (type-1 DM) and 30 patients with autoimmune thyrotoxicosis (Graves' disease). T lymphocyte TCR expression was assessed by fluorescence-activated flow cytometry on peripheral blood mononuclear cells using MoAbs UCHT1 (CD3), TCR delta 1 (gamma delta TCR), WT31 and beta F1 (alpha beta TCR) and both the percentage of T cells expressing gamma delta and the ratio gamma delta/alpha beta were calculated. In the diabetic patients gamma delta cells were not significantly different from the control group (7.7 +/- 54% versus 8.0 +/- 5.5% of T cells, P NS). There was no relation between the proportion of gamma delta lymphocytes and the presence of islet cell antibodies (ICA) in the sera. The Graves' patients showed a tendency towards a higher proportion of gamma delta T lymphocytes than the controls (gamma delta/alpha beta ratios: 0.095 +/- 0.047 versus 0.063 +/- 0.022, P = 0.03). In 14 Graves' patients the number of gamma delta were measured in paired samples of peripheral and intrathyroidal lymphocytes, demonstrating an expansion of gamma delta within the thyroid glands (0.21 +/- 0.3 versus 0.095 +/- 0.047, P = 0.032). Immunohistochemical studies showed that gamma delta cells were scattered among the predominant alpha beta lymphocytes infiltrating the thyroid gland and that they account for 10% of intraepithelial lymphocytes. No relation was found between the increase of gamma delta lymphocytes and any clinical features. PMID:8485915

The profile of immune modulation by cannabidiol (CBD) involves deregulation of nuclear factor of activated T cells (NFAT).

PubMed

Kaplan, Barbara L F; Springs, Alison E B; Kaminski, Norbert E

2008-09-15

Cannabidiol (CBD) is a cannabinoid compound derived from Cannabis Sativa that does not possess high affinity for either the CB1 or CB2 cannabinoid receptors. Similar to other cannabinoids, we demonstrated previously that CBD suppressed interleukin-2 (IL-2) production from phorbol ester plus calcium ionophore (PMA/Io)-activated murine splenocytes. Thus, the focus of the present studies was to further characterize the effect of CBD on immune function. CBD also suppressed IL-2 and interferon-gamma (IFN-gamma) mRNA expression, proliferation, and cell surface expression of the IL-2 receptor alpha chain, CD25. While all of these observations support the fact that CBD suppresses T cell function, we now demonstrate that CBD suppressed IL-2 and IFN-gamma production in purified splenic T cells. CBD also suppressed activator protein-1 (AP-1) and nuclear factor of activated T cells (NFAT) transcriptional activity, which are critical regulators of IL-2 and IFN-gamma. Furthermore, CBD suppressed the T cell-dependent anti-sheep red blood cell immunoglobulin M antibody forming cell (anti-sRBC IgM AFC) response. Finally, using splenocytes derived from CB1(-/-)/CB2(-/-) mice, it was determined that suppression of IL-2 and IFN-gamma and suppression of the in vitro anti-sRBC IgM AFC response occurred independently of both CB1 and CB2. However, the magnitude of the immune response to sRBC was significantly depressed in CB1(-/-)/CB2(-/-) mice. Taken together, these data suggest that CBD suppresses T cell function and that CB1 and/or CB2 play a critical role in the magnitude of the in vitro anti-sRBC IgM AFC response.

Subunits of the Snf1 kinase heterotrimer show interdependence for association and activity.

PubMed

Elbing, Karin; Rubenstein, Eric M; McCartney, Rhonda R; Schmidt, Martin C

2006-09-08

The Snf1 kinase and its mammalian orthologue, the AMP-activated protein kinase (AMPK), function as heterotrimers composed of a catalytic alpha-subunit and two non-catalytic subunits, beta and gamma. The beta-subunit is thought to hold the complex together and control subcellular localization whereas the gamma-subunit plays a regulatory role by binding to and blocking the function of an auto-inhibitory domain (AID) present in the alpha-subunit. In addition, catalytic activity requires phosphorylation by a distinct upstream kinase. In yeast, any one of three Snf1-activating kinases, Sak1, Tos3, or Elm1, can fulfill this role. We have previously shown that Sak1 is the only Snf1-activating kinase that forms a stable complex with Snf1. Here we show that the formation of the Sak1.Snf1 complex requires the beta- and gamma-subunits in vivo. However, formation of the Sak1.Snf1 complex is not necessary for glucose-regulated phosphorylation of the Snf1 activation loop. Snf1 kinase purified from cells lacking the beta-subunits do not contain any gamma-subunit, indicating that the Snf1 kinase does not form a stable alphagamma dimer in vivo. In vitro kinase assays using purified full-length and truncated Snf1 proteins demonstrate that the kinase domain, which lacks the AID, is significantly more active than the full-length Snf1 protein. Addition of purified beta- and gamma-subunits could stimulate the kinase activity of the full-length alpha-subunit but only when all three subunits were present, suggesting an interdependence of all three subunits for assembly of a functional complex.

Constraints on the bulk Lorentz factor of gamma-ray bursts with the detection rate by Fermi LAT

NASA Astrophysics Data System (ADS)

Chen, Ye; Liu, Ruo-Yu; Wang, Xiang-Yu

2018-05-01

The bulk Lorentz factor(Γ) of the outflow is an essential parameter to understanding the physics of gamma-ray burst (GRB). Informations about the Lorentz factors of some individual GRBs have been obtained from the spectral features of the high-energy gamma-ray emissions (>100 MeV), assuming that the spectral breaks or cutoffs are due to the pair-production attenuation (i.e., γγ → e+e-). In this paper, we attempt to interpret the dependence of the LAT detection rate of GRBs on the number of high-energy gamma-rays, taking into account the attenuation effect. We first simulate a long-GRB sample with Monte Carlo method using the luminosity function, rate distribution with redshift and properties of the GRB spectrum. To characterize the distribution of the Lorentz factors, we assume that the Lorentz factors follow the relation Γ =Γ _0E_iso,52k, where Eiso, 52 is the isotropic photon energy in unit of 1052erg. After taking into account the attenuation effect related with the above Lorentz factor distribution, we are able to reproduce the LAT-detected rate of GRBs as the function of the number of gamma-rays for suitable choice of the values of Γ0 and k. The result suggests that the distribution of the bulk Lorentz factor for the majority of GRBs is in the range of 50 - 250.

Constraints onthe bulk Lorentz factor of gamma-ray burstswith the detection rate by Fermi LAT

NASA Astrophysics Data System (ADS)

Chen, Ye; Liu, Ruo-Yu; Wang, Xiang-Yu

2018-07-01

The bulk Lorentz factor (Γ) of the outflow is an essential parameter for understanding the physics of gamma-ray burst (GRB). Informations about the Lorentz factors of some individual GRBs have been obtained from the spectral features of the high-energy gamma-ray emissions (>100 MeV), assuming that the spectral breaks or cutoffs are due to the pair-production attenuation (i.e. γγ → e+e-). In this paper, we attempt to interpret the dependence of the Large Area Telescope (LAT) detection rate of GRBs on the number of high-energy gamma-rays, taking into account the attenuation effect. We first simulate a long-GRB sample with Monte Carlo method using the luminosity function, rate distribution with redshift, and properties of the GRB spectrum. To characterize the distribution of the Lorentz factors, we assume that the Lorentz factors follow the relation Γ =Γ _0E_{iso, 52}k, where Eiso,52 is the isotropic photon energy in unit of 1052 erg. After taking into account the attenuation effect related with the above Lorentz factor distribution, we are able to reproduce the LAT-detected rate of GRBs as the function of the number of gamma-rays for suitable choice of the values of Γ0 and k. The result suggests that the distribution of the bulk Lorentz factor for the majority of GRBs is in the range of 50-250.

The Role of Stress Proteins in Cell Stabilization: A Perspective from an Extremophile

NASA Technical Reports Server (NTRS)

Trent, Jonathan

2001-01-01

The existence of organisms that live at near boiling temperatures is living proof that all of the complex biochemical machinery of life can be adapted to function under these harsh conditions. The purpose of our research is to elucidate the role of a group of proteins known as heat shock proteins or HSP60s in this adaptation to high temperatures. HSP60s are found in all organisms and they are among the most highly conserved proteins known. We are investigating HSP60s in an organism growing at 80 C and pH 2.0 (Sulfolobus shibatae). This organism produces three closely-related HSP60 proteins, referred to as HSP60 alpha, beta, and gamma. Our DOE-funded research during the last two years has focused on clarifying the role of FiSP60 alpha and beta. These are among the two most abundant proteins in S. shibatae grown at high temperatures and significantly increase in abundance when the cells are exposed to near-lethal temperatures. We have demonstrated that these proteins protect the cells from lethal temperatures by stabilizing their membranes. During this last year we have been studying gamma, which was discovered by genome sequence analysis but nothing was known about its function. We have determined that gamma is only expressed at low temperatures. that it interacts with alpha and beta, and that it influences their ability to form higher-order structures critical to their function. We propose that gamma modulates HSP60 function at low temperatures.

Quark-hadron duality constraints on $$\\gamma Z$$ box corrections to parity-violating elastic scattering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hall, Nathan L.; Blunden, Peter G.; Melnitchouk, Wally

2015-12-08

We examine the interference \\gamma Z box corrections to parity-violating elastic electron--proton scattering in the light of the recent observation of quark-hadron duality in parity-violating deep-inelastic scattering from the deuteron, and the approximate isospin independence of duality in the electromagnetic nucleon structure functions down to Q 2 \\approx 1 GeV 2. Assuming that a similar behavior also holds for the \\gamma Z proton structure functions, we find that duality constrains the γ Z box correction to the proton's weak charge to be Re V γ Z V = (5.4 \\pm 0.4) \\times 10 -3 at the kinematics of the Qmore » weak experiment. Within the same model we also provide estimates of the γ Z corrections for future parity-violating experiments, such as MOLLER at Jefferson Lab and MESA at Mainz.« less

Cosmic-Ray Background Flux Model Baed on a Gamma-Ray Large Area Space Telescope Baloon Flight Engineering

NASA Technical Reports Server (NTRS)

2002-01-01

Cosmic-ray background fluxes were modeled based on existing measurements and theories and are presented here. The model, originally developed for the Gamma-ray Large Area Space Telescope (GLAST) Balloon Experiment, covers the entire solid angle (4(pi) sr), the sensitive energy range of the instrument ((approx) 10 MeV to 100 GeV) and abundant components (proton, alpha, e(sup -), e(sup +), (mu)(sup -), (mu)(sup +) and gamma). It is expressed in analytic functions in which modulations due to the solar activity and the Earth geomagnetism are parameterized. Although the model is intended to be used primarily for the GLAST Balloon Experiment, model functions in low-Earth orbit are also presented and can be used for other high energy astrophysical missions. The model has been validated via comparison with the data of the GLAST Balloon Experiment.

Ultra-wide Range Gamma Detector System for Search and Locate Operations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Odell, D. Mackenzie Odell; Harpring, Larry J.; Moore, Frank S. Jr.

2005-10-26

Collecting debris samples following a nuclear event requires that operations be conducted from a considerable stand-off distance. An ultra-wide range gamma detector system has been constructed to accomplish both long range radiation search and close range hot sample collection functions. Constructed and tested on a REMOTEC Andros platform, the system has demonstrated reliable operation over six orders of magnitude of gamma dose from 100's of uR/hr to over 100 R/hr. Functional elements include a remotely controlled variable collimator assembly, a NaI(Tl)/photomultiplier tube detector, a proprietary digital radiation instrument, a coaxially mounted video camera, a digital compass, and both local andmore » remote control computers with a user interface designed for long range operations. Long range sensitivity and target location, as well as close range sample selection performance are presented.« less

Application of quasi-distributions for solving inverse problems of neutron and {gamma}-ray transport

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pogosbekyan, L.R.; Lysov, D.A.

The considered inverse problems deal with the calculation of the unknown values of nuclear installations by means of the known (goal) functionals of neutron/{gamma}-ray distributions. The example of these problems might be the calculation of the automatic control rods position as function of neutron sensors reading, or the calculation of experimentally-corrected values of cross-sections, isotopes concentration, fuel enrichment via the measured functional. The authors have developed the new method to solve inverse problem. It finds flux density as quasi-solution of the particles conservation linear system adjointed to equalities for functionals. The method is more effective compared to the one basedmore » on the classical perturbation theory. It is suitable for vectorization and it can be used successfully in optimization codes.« less

mrpy: Renormalized generalized gamma distribution for HMF and galaxy ensemble properties comparisons

NASA Astrophysics Data System (ADS)

Murray, Steven G.; Robotham, Aaron S. G.; Power, Chris

2018-02-01

mrpy calculates the MRP parameterization of the Halo Mass Function. It calculates basic statistics of the truncated generalized gamma distribution (TGGD) with the TGGD class, including mean, mode, variance, skewness, pdf, and cdf. It generates MRP quantities with the MRP class, such as differential number counts and cumulative number counts, and offers various methods for generating normalizations. It can generate the MRP-based halo mass function as a function of physical parameters via the mrp_b13 function, and fit MRP parameters to data in the form of arbitrary curves and in the form of a sample of variates with the SimFit class. mrpy also calculates analytic hessians and jacobians at any point, and allows the user to alternate parameterizations of the same form via the reparameterize module.

Midi-maxi computer interaction in the interpretation of nuclear medicine procedures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schlapper, G.A.

1977-01-01

A study of renal function with an Anger Gamma Camera coupled with a Digital Equipment Corporation Gamma-11 System and an IBM System 370 demonstrates the potential of quantitative determinations of physiological function through the application of midi-maxi computer interaction in the interpretation of nuclear medicine procedures. It is shown that radiotracers can provide an opportunity to assess physiological processes of renal function by noninvasively following the path of a tracer as a function of time. Time-activity relationships obtained over seven anatomically defined regions are related to parameters of a seven compartment model employed to describe the renal clearance process. Themore » values obtained for clinically significant parameters agree with known renal pathophysiology. Differentiation of failure of acute, chronic, and obstructive forms is indicated.« less

Characterization of a tin-loaded liquid scintillator for gamma spectroscopy and neutron detection

NASA Astrophysics Data System (ADS)

Wen, Xianfei; Harvey, Taylor; Weinmann-Smith, Robert; Walker, James; Noh, Young; Farley, Richard; Enqvist, Andreas

2018-07-01

A tin-loaded liquid scintillator has been developed for gamma spectroscopy and neutron detection. The scintillator was characterized in regard to energy resolution, pulse shape discrimination, neutron light output function, and timing resolution. The loading of tin into scintillators with low effective atomic number was demonstrated to provide photopeaks with acceptable energy resolution. The scintillator was shown to have reasonable neutron/gamma discrimination capability based on the charge comparison method. The effect on the discrimination quality of the total charge integration time and the initial delay time for tail charge integration was studied. To obtain the neutron light output function, the time-of-flight technique was utilized with a 252Cf source. The light output function was validated with the MCNPX-PoliMi code by comparing the measured and simulated pule height spectra. The timing resolution of the developed scintillator was also evaluated. The tin-loading was found to have negligible impact on the scintillation decay times. However, a relatively large degradation of timing resolution was observed due to the reduced light yield.

Human immunodeficiency virus (HIV) type 1 Vpr induces differential regulation of T cell costimulatory molecules: Direct effect of Vpr on T cell activation and immune function

DOE Office of Scientific and Technical Information (OSTI.GOV)

Venkatachari, Narasimhan J.; Majumder, Biswanath; Ayyavoo, Velpandi

2007-02-20

Human immunodeficiency virus type 1 (HIV-1) viral proteins disrupt the normal host cellular immune pathways thus exploiting the cellular machinery for replication, survival and to escape host immune attack. Here we evaluated the direct effects of HIV-1 Vpr-mediated immune modulation of infected T cells. Vpr specifically downregulated the expression of CD28 and increased the expression of CTLA-4, whereas no significant difference in the expression of CD25 and HLA-DR was observed. Interferon gamma (IFN-{gamma}) production in T cells was evaluated as a measure of the downstream effector functions. Results indicate that Vpr significantly inhibited IFN-{gamma} production and this may, in part,more » due to Vpr's ability to inhibit the nuclear translocation of NF-{kappa}B, and its transcriptional regulation. Together these results support that HIV-1 Vpr selectively dysregulates the immune functions at multiple levels and exerts its inhibitory effects in the presence of other viral proteins.« less

Lens elliptic gamma function solution of the Yang-Baxter equation at roots of unity

NASA Astrophysics Data System (ADS)

Kels, Andrew P.; Yamazaki, Masahito

2018-02-01

We study the root of unity limit of the lens elliptic gamma function solution of the star-triangle relation, for an integrable model with continuous and discrete spin variables. This limit involves taking an elliptic nome to a primitive rNth root of unity, where r is an existing integer parameter of the lens elliptic gamma function, and N is an additional integer parameter. This is a singular limit of the star-triangle relation, and at subleading order of an asymptotic expansion, another star-triangle relation is obtained for a model with discrete spin variables in {Z}rN . Some special choices of solutions of equation of motion are shown to result in well-known discrete spin solutions of the star-triangle relation. The saddle point equations themselves are identified with three-leg forms of ‘3D-consistent’ classical discrete integrable equations, known as Q4 and Q3(δ=0) . We also comment on the implications for supersymmetric gauge theories, and in particular comment on a close parallel with the works of Nekrasov and Shatashvili.

GRAYSKY-A new gamma-ray skyshine code

DOE Office of Scientific and Technical Information (OSTI.GOV)

Witts, D.J.; Twardowski, T.; Watmough, M.H.

1993-01-01

This paper describes a new prototype gamma-ray skyshine code GRAYSKY (Gamma-RAY SKYshine) that has been developed at BNFL, as part of an industrially based master of science course, to overcome the problems encountered with SKYSHINEII and RANKERN. GRAYSKY is a point kernel code based on the use of a skyshine response function. The scattering within source or shield materials is accounted for by the use of buildup factors. This is an approximate method of solution but one that has been shown to produce results that are acceptable for dose rate predictions on operating plants. The novel features of GRAYSKY aremore » as follows: 1. The code is fully integrated with a semianalytical point kernel shielding code, currently under development at BNFL, which offers powerful solid-body modeling capabilities. 2. The geometry modeling also allows the skyshine response function to be used in a manner that accounts for the shielding of air-scattered radiation. 3. Skyshine buildup factors calculated using the skyshine response function have been used as well as dose buildup factors.« less

The theta/gamma discrete phase code occuring during the hippocampal phase precession may be a more general brain coding scheme.

PubMed

Lisman, John

2005-01-01

In the hippocampus, oscillations in the theta and gamma frequency range occur together and interact in several ways, indicating that they are part of a common functional system. It is argued that these oscillations form a coding scheme that is used in the hippocampus to organize the readout from long-term memory of the discrete sequence of upcoming places, as cued by current position. This readout of place cells has been analyzed in several ways. First, plots of the theta phase of spikes vs. position on a track show a systematic progression of phase as rats run through a place field. This is termed the phase precession. Second, two cells with nearby place fields have a systematic difference in phase, as indicated by a cross-correlation having a peak with a temporal offset that is a significant fraction of a theta cycle. Third, several different decoding algorithms demonstrate the information content of theta phase in predicting the animal's position. It appears that small phase differences corresponding to jitter within a gamma cycle do not carry information. This evidence, together with the finding that principle cells fire preferentially at a given gamma phase, supports the concept of theta/gamma coding: a given place is encoded by the spatial pattern of neurons that fire in a given gamma cycle (the exact timing within a gamma cycle being unimportant); sequential places are encoded in sequential gamma subcycles of the theta cycle (i.e., with different discrete theta phase). It appears that this general form of coding is not restricted to readout of information from long-term memory in the hippocampus because similar patterns of theta/gamma oscillations have been observed in multiple brain regions, including regions involved in working memory and sensory integration. It is suggested that dual oscillations serve a general function: the encoding of multiple units of information (items) in a way that preserves their serial order. The relationship of such coding to that proposed by Singer and von der Malsburg is discussed; in their scheme, theta is not considered. It is argued that what theta provides is the absolute phase reference needed for encoding order. Theta/gamma coding therefore bears some relationship to the concept of "word" in digital computers, with word length corresponding to the number of gamma cycles within a theta cycle, and discrete phase corresponding to the ordered "place" within a word. Copyright 2005 Wiley-Liss, Inc.

Cost-effectiveness of gammaCore (non-invasive vagus nerve stimulation) for acute treatment of episodic cluster headache.

PubMed

Mwamburi, Mkaya; Liebler, Eric J; Tenaglia, Andrew T

2017-11-01

Cluster headache is a debilitating disease characterized by excruciatingly painful attacks that affects 0.15% to 0.4% of the US population. Episodic cluster headache manifests as circadian and circannual seasonal bouts of attacks, each lasting 15 to 180 minutes, with periods of remission. In chronic cluster headache, the attacks occur throughout the year with no periods of remission. While existing treatments are effective for some patients, many patients continue to suffer. There are only 2 FDA-approved medications for episodic cluster headache in the United States, while others, such as high-flow oxygen, are used off-label. Episodic cluster headache is associated with comorbidities and affects work, productivity, and daily functioning. The economic burden of episodic cluster headache is considerable, costing more than twice that of nonheadache patients. gammaCore adjunct to standard of care (SoC) was found to have superior efficacy in treatment of acute episodic cluster headaches compared with sham-gammaCore used with SoC in ACT1 and ACT2 trials. However, the economic impact has not been characterized for this indication. We conducted a cost-effectiveness analysis of gammaCore adjunct to SoC compared with SoC alone for the treatment of acute pain associated with episodic cluster headache attacks. The model structure was based on treatment of acute attacks with 3 outcomes: failures, nonresponders, and responders. The time horizon of the model is 1 year using a payer perspective with uncertainty incorporated. Parameter inputs were derived from primary data from the randomized controlled trials for gammaCore. The mean annual costs associated with the gammaCore-plus-SoC arm was $9510, and mean costs for the SoC-alone arm was $10,040. The mean quality-adjusted life years for gammaCore-plus-SoC arm were 0.83, and for the SoC-alone arm, they were 0.74. The gammaCore-plus-SoC arm was dominant over SoC alone. All 1-way and multiway sensitivity analyses were cost-effective using a threshold of $20,000. gammaCore dominance, representing savings, was driven by superior efficacy, improvement in quality of life (QoL), and reduction in costs associated with successful and consistent abortion of episodic attacks. These findings serve as additional economic evidence to support coverage for gammaCore. Additional real-world data are needed to characterize the long-term impact of gammaCore on comorbidities, utilization, QoL, daily functioning, productivity, and social engagement of these patients, and for other indications.

Activation-induced proteolysis of cytoplasmic domain of zeta in T cell receptors and Fc receptors.

PubMed

Taupin, J L; Anderson, P

1994-12-01

The CD3-T cell receptor (TCR) complex on T cells and the Fc gamma receptor type III (Fc gamma RIII)-zeta-gamma complex on natural killer cells are functionally analogous activation receptors that associate with a family of disulfide-linked dimers composed of the related subunits zeta and gamma. Immunochemical analysis of receptor complexes separated on two-dimensional diagonal gels allowed the identification of a previously uncharacterized zeta-p14 heterodimer. zeta-p14 is a component of both CD3-TCR and Fc gamma RIII-zeta-gamma. Peptide mapping analysis shows that p14 is structurally related to zeta, suggesting that it is either: (i) derived from zeta proteolytically or (ii) the product of an alternatively spliced mRNA. The observation that COS cells transformed with a cDNA encoding zeta express zeta-p14 supports the former possibility. The expression of CD3-TCR complexes including zeta-p14 increases following activation with phorbol 12-myristate 13-acetate or concanavalin A, suggesting that proteolysis of zeta may contribute to receptor modulation or desensitization.

Radio galaxies dominate the high-energy diffuse gamma-ray background

DOE PAGES

Hooper, Dan; Linden, Tim; Lopez, Alejandro

2016-08-09

It has been suggested that unresolved radio galaxies and radio quasars (sometimes referred to as misaligned active galactic nuclei) could be responsible for a significant fraction of the observed diffuse gamma-ray background. In this study, we use the latest data from the Fermi Gamma-Ray Space Telescope to characterize the gamma-ray emission from a sample of 51 radio galaxies. In addition to those sources that had previously been detected using Fermi data, we report here the first statistically significant detection of gamma-ray emission from the radio galaxies 3C 212, 3C 411, and B3 0309+411B. Combining this information with the radio fluxes,more » radio luminosity function, and redshift distribution of this source class, we find that radio galaxies dominate the diffuse gamma-ray background, generating 77.2(+25.4)(-9.4)% of this emission at energies above ~1 GeV . We discuss the implications of this result and point out that it provides support for scenarios in which IceCube's high-energy astrophysical neutrinos also originate from the same population of radio galaxies.« less

On uniform constants of strong uniqueness in Chebyshev approximations and fundamental results of N. G. Chebotarev

NASA Astrophysics Data System (ADS)

Marinov, Anatolii V.

2011-06-01

In the problem of the best uniform approximation of a continuous real-valued function f\\in C(Q) in a finite-dimensional Chebyshev subspace M\\subset C(Q), where Q is a compactum, one studies the positivity of the uniform strong uniqueness constant \\gamma(N)=\\inf\\{\\gamma(f)\\colon f\\in N\\}. Here \\gamma(f) stands for the strong uniqueness constant of an element f_M\\in M of best approximation of f, that is, the largest constant \\gamma>0 such that the strong uniqueness inequality \\Vert f-\\varphi\\Vert\\ge\\Vert f-f_M\\Vert+\\gamma\\Vert f_M-\\varphi\\Vert holds for any \\varphi\\in M. We obtain a characterization of the subsets N\\subset C(Q) for which there is a neighbourhood O(N) of N satisfying the condition \\gamma(O(N))>0. The pioneering results of N. G. Chebotarev were published in 1943 and concerned the sharpness of the minimum in minimax problems and the strong uniqueness of algebraic polynomials of best approximation. They seem to have been neglected by the specialists, and we discuss them in detail.

High-gamma band fronto-temporal coherence as a measure of functional connectivity in speech motor control.

PubMed

Kingyon, J; Behroozmand, R; Kelley, R; Oya, H; Kawasaki, H; Narayanan, N S; Greenlee, J D W

2015-10-01

The neural basis of human speech is unclear. Intracranial electrophysiological recordings have revealed that high-gamma band oscillations (70-150Hz) are observed in the frontal lobe during speech production and in the temporal lobe during speech perception. Here, we tested the hypothesis that the frontal and temporal brain regions had high-gamma coherence during speech. We recorded electrocorticography (ECoG) from the frontal and temporal cortices of five humans who underwent surgery for medically intractable epilepsy, and studied coherence between the frontal and temporal cortex during vocalization and playback of vocalization. We report two novel results. First, we observed high-gamma band as well as theta (4-8Hz) coherence between frontal and temporal lobes. Second, both high-gamma and theta coherence were stronger when subjects were actively vocalizing as compared to playback of the same vocalizations. These findings provide evidence that coupling between sensory-motor networks measured by high-gamma coherence plays a key role in feedback-based monitoring and control of vocal output for human vocalization. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

Investigation of natural effective gamma dose rates case study: Ardebil Province in Iran

PubMed Central

2012-01-01

Gamma rays pose enough energy to induce chemical changes that may be biologically important for the normal functioning of body cells. The external exposure of human beings to natural environmental gamma radiation normally exceeds that from all man-made sources combined. In this research natural background gamma dose rates and corresponding annual effective doses were determined for selected cities of Ardebil province. Outdoor gamma dose rates were measured using an Ion Chamber Survey Meter in 105 locations in selected districts. Average absorbed doses for Ardebil, Sar-Ein, Germy, Neer, Shourabil Recreational Lake, and Kosar were determined as 265, 219, 344, 233, 352, and 358 nSv/h, respectively. Although dose rates recorded for Germi and Kosar are comparable with some areas with high natural radiation background, however, the dose rates in other districts are well below the levels reported for such locations. Average annual effective dose due to indoor and outdoor gamma radiation for Ardebil province was estimated as 1.73 (1.35–2.39) mSv, which is on average 2 times higher than the world population weighted average. PMID:23369115

On computing closed forms for summations. [polynomials and rational functions

NASA Technical Reports Server (NTRS)

Moenck, R.

1977-01-01

The problem of finding closed forms for a summation involving polynomials and rational functions is considered. A method closely related to Hermite's method for integration of rational functions derived. The method expresses the sum of a rational function as a rational function part and a transcendental part involving derivatives of the gamma function.

Nuclear Forensics using Gamma-ray Spectroscopy

NASA Astrophysics Data System (ADS)

Norman, E. B.

2016-09-01

Much of George Dracoulis's research career was devoted to utilising gamma-ray spectroscopy in fundamental studies in nuclear physics. This same technology is useful in a wide range of applications in the area of nuclear forensics. Over the last several years, our research group has made use of both high- and low-resolution gamma-ray spectrometers to: identify the first sample of plutonium large enough to be weighed; determine the yield of the Trinity nuclear explosion; measure fission fragment yields as a function of target nucleus and neutron energy; and observe fallout in the U. S. from the Fukushima nuclear reactor accident.

Neutron energy determination with a high-purity germanium detector

NASA Technical Reports Server (NTRS)

Beck, Gene A.

1992-01-01

Two areas that are related to planetary gamma-ray spectrometry are investigated. The first task was the investigation of gamma rays produced by high-energy charged particles and their secondaries in planetary surfaces by means of thick target bombardments. The second task was the investigation of the effects of high-energy neutrons on gamma-ray spectral features obtained with high-purity Ge-detectors. For both tasks, as a function of the funding level, the experimental work was predominantly tied to that of other researchers, whenever there was an opportunity to participate in bombardment experiments at large or small accelerators for charged particles.

Code CUGEL: A code to unfold Ge(Li) spectrometer polyenergetic gamma photon experimental distributions

NASA Technical Reports Server (NTRS)

Steyn, J. J.; Born, U.

1970-01-01

A FORTRAN code was developed for the Univac 1108 digital computer to unfold lithium-drifted germanium semiconductor spectrometers, polyenergetic gamma photon experimental distributions. It was designed to analyze the combination continuous and monoenergetic gamma radiation field of radioisotope volumetric sources. The code generates the detector system response matrix function and applies it to monoenergetic spectral components discretely and to the continuum iteratively. It corrects for system drift, source decay, background, and detection efficiency. Results are presented in digital form for differential and integrated photon number and energy distributions, and for exposure dose.

Overexpression of Dyrk1A, a Down Syndrome Candidate, Decreases Excitability and Impairs Gamma Oscillations in the Prefrontal Cortex.

PubMed

Ruiz-Mejias, Marcel; Martinez de Lagran, Maria; Mattia, Maurizio; Castano-Prat, Patricia; Perez-Mendez, Lorena; Ciria-Suarez, Laura; Gener, Thomas; Sancristobal, Belen; García-Ojalvo, Jordi; Gruart, Agnès; Delgado-García, José M; Sanchez-Vives, Maria V; Dierssen, Mara

2016-03-30

The dual-specificity tyrosine phosphorylation-regulated kinase DYRK1A is a serine/threonine kinase involved in neuronal differentiation and synaptic plasticity and a major candidate of Down syndrome brain alterations and cognitive deficits. DYRK1A is strongly expressed in the cerebral cortex, and its overexpression leads to defective cortical pyramidal cell morphology, synaptic plasticity deficits, and altered excitation/inhibition balance. These previous observations, however, do not allow predicting how the behavior of the prefrontal cortex (PFC) network and the resulting properties of its emergent activity are affected. Here, we integrate functional, anatomical, and computational data describing the prefrontal network alterations in transgenic mice overexpressingDyrk1A(TgDyrk1A). Usingin vivoextracellular recordings, we show decreased firing rate and gamma frequency power in the prefrontal network of anesthetized and awakeTgDyrk1Amice. Immunohistochemical analysis identified a selective reduction of vesicular GABA transporter punctae on parvalbumin positive neurons, without changes in the number of cortical GABAergic neurons in the PFC ofTgDyrk1Amice, which suggests that selective disinhibition of parvalbumin interneurons would result in an overinhibited functional network. Using a conductance-based computational model, we quantitatively demonstrate that this alteration could explain the observed functional deficits including decreased gamma power and firing rate. Our results suggest that dysfunction of cortical fast-spiking interneurons might be central to the pathophysiology of Down syndrome. DYRK1Ais a major candidate gene in Down syndrome. Its overexpression results into altered cognitive abilities, explained by defective cortical microarchitecture and excitation/inhibition imbalance. An open question is how these deficits impact the functionality of the prefrontal cortex network. Combining functional, anatomical, and computational approaches, we identified decreased neuronal firing rate and deficits in gamma frequency in the prefrontal cortices of transgenic mice overexpressingDyrk1A We also identified a reduction of vesicular GABA transporter punctae specifically on parvalbumin positive interneurons. Using a conductance-based computational model, we demonstrate that this decreased inhibition on interneurons recapitulates the observed functional deficits, including decreased gamma power and firing rate. Our results suggest that dysfunction of cortical fast-spiking interneurons might be central to the pathophysiology of Down syndrome. Copyright © 2016 the authors 0270-6474/16/363649-12$15.00/0.

Feasibility of a high-speed gamma-camera design using the high-yield-pileup-event-recovery method.

PubMed

Wong, W H; Li, H; Uribe, J; Baghaei, H; Wang, Y; Yokoyama, S

2001-04-01

Higher count-rate gamma cameras than are currently used are needed if the technology is to fulfill its promise in positron coincidence imaging, radionuclide therapy dosimetry imaging, and cardiac first-pass imaging. The present single-crystal design coupled with conventional detector electronics and the traditional Anger-positioning algorithm hinder higher count-rate imaging because of the pileup of gamma-ray signals in the detector and electronics. At an interaction rate of 2 million events per second, the fraction of nonpileup events is < 20% of the total incident events. Hence, the recovery of pileup events can significantly increase the count-rate capability, increase the yield of imaging photons, and minimize image artifacts associated with pileups. A new technology to significantly enhance the performance of gamma cameras in this area is introduced. We introduce a new electronic design called high-yield-pileup-event-recovery (HYPER) electronics for processing the detector signal in gamma cameras so that the individual gamma energies and positions of pileup events, including multiple pileups, can be resolved and recovered despite the mixing of signals. To illustrate the feasibility of the design concept, we have developed a small gamma-camera prototype with the HYPER-Anger electronics. The camera has a 10 x 10 x 1 cm NaI(Tl) crystal with four photomultipliers. Hot-spot and line sources with very high 99mTc activities were imaged. The phantoms were imaged continuously from 60,000 to 3,500,000 counts per second to illustrate the efficacy of the method as a function of counting rates. At 2-3 million events per second, all phantoms were imaged with little distortion, pileup, and dead-time loss. At these counting rates, multiple pileup events (> or = 3 events piling together) were the predominate occurrences, and the HYPER circuit functioned well to resolve and recover these events. The full width at half maximum of the line-spread function at 3,000,000 counts per second was 1.6 times that at 60,000 counts per second. This feasibility study showed that the HYPER electronic concept works; it can significantly increase the count-rate capability and dose efficiency of gamma cameras. In a larger clinical camera, multiple HYPER-Anger circuits may be implemented to further improve the imaging counting rates that we have shown by multiple times. This technology would facilitate the use of gamma cameras for radionuclide therapy dosimetry imaging, cardiac first-pass imaging, and positron coincidence imaging and the simultaneous acquisition of transmission and emission data using different isotopes with less cross-contamination between transmission and emission data.

Dual role of SLP-76 in mediating T cell receptor-induced activation of phospholipase C-gamma1.

PubMed

Beach, Dvora; Gonen, Ronnie; Bogin, Yaron; Reischl, Ilona G; Yablonski, Deborah

2007-02-02

Phospholipase C-gamma1 (PLC-gamma1) activation depends on a heterotrimeric complex of adaptor proteins composed of LAT, Gads, and SLP-76. Upon T cell receptor stimulation, a portion of PLC-gamma1 is recruited to a detergent-resistant membrane fraction known as the glycosphingolipid-enriched membrane microdomains (GEMs), or lipid rafts, to which LAT is constitutively localized. In addition to LAT, PLC-gamma1 GEM recruitment depended on SLP-76, and, in particular, required the Gads-binding domain of SLP-76. The N-terminal tyrosine phosphorylation sites and P-I region of SLP-76 were not required for PLC-gamma1 GEM recruitment, but were required for PLC-gamma1 phosphorylation at Tyr(783). Thus, GEM recruitment can be insufficient for full activation of PLC-gamma1 in the absence of a second SLP-76-mediated event. Indeed, a GEM-targeted derivative of PLC-gamma1 depended on SLP-76 for T cell receptor-induced phosphorylation at Tyr783 and subsequent NFAT activation. On a biochemical level, SLP-76 inducibly associated with both Vav and catalytically active ITK, which efficiently phosphorylated a PLC-gamma1 fragment at Tyr783 in vitro. Both associations were disrupted upon mutation of the N-terminal tyrosine phosphorylation sites of SLP-76. The P-I region deletion disrupted Vav association and reduced SLP-76-associated kinase activity. A smaller deletion within the P-I region, which does not impair PLC-gamma1 activation, did not impair the association with Vav, but reduced SLP-76-associated kinase activity. These results provide new insight into the multiple roles of SLP-76 and the functional importance of its interactions with other signaling proteins.

Intrasteric control of AMPK via the gamma1 subunit AMP allosteric regulatory site.

PubMed

Adams, Julian; Chen, Zhi-Ping; Van Denderen, Bryce J W; Morton, Craig J; Parker, Michael W; Witters, Lee A; Stapleton, David; Kemp, Bruce E

2004-01-01

AMP-activated protein kinase (AMPK) is a alphabetagamma heterotrimer that is activated in response to both hormones and intracellular metabolic stress signals. AMPK is regulated by phosphorylation on the alpha subunit and by AMP allosteric control previously thought to be mediated by both alpha and gamma subunits. Here we present evidence that adjacent gamma subunit pairs of CBS repeat sequences (after Cystathionine Beta Synthase) form an AMP binding site related to, but distinct from the classical AMP binding site in phosphorylase, that can also bind ATP. The AMP binding site of the gamma(1) CBS1/CBS2 pair, modeled on the structures of the CBS sequences present in the inosine monophosphate dehydrogenase crystal structure, contains three arginine residues 70, 152, and 171 and His151. The yeast gamma homolog, snf4 contains a His151Gly substitution, and when this is introduced into gamma(1), AMP allosteric control is substantially lost and explains why the yeast snf1p/snf4p complex is insensitive to AMP. Arg70 in gamma(1) corresponds to the site of mutation in human gamma(2) and pig gamma(3) genes previously identified to cause an unusual cardiac phenotype and glycogen storage disease, respectively. Mutation of any of AMP binding site Arg residues to Gln substantially abolishes AMP allosteric control in expressed AMPK holoenzyme. The Arg/Gln mutations also suppress the previously described inhibitory properties of ATP and render the enzyme constitutively active. We propose that ATP acts as an intrasteric inhibitor by bridging the alpha and gamma subunits and that AMP functions to derepress AMPK activity.

Clinical significance and developmental changes of auditory-language-related gamma activity

PubMed Central

Kojima, Katsuaki; Brown, Erik C.; Rothermel, Robert; Carlson, Alanna; Fuerst, Darren; Matsuzaki, Naoyuki; Shah, Aashit; Atkinson, Marie; Basha, Maysaa; Mittal, Sandeep; Sood, Sandeep; Asano, Eishi

2012-01-01

OBJECTIVE We determined the clinical impact and developmental changes of auditory-language-related augmentation of gamma activity at 50–120 Hz recorded on electrocorticography (ECoG). METHODS We analyzed data from 77 epileptic patients ranging 4 – 56 years in age. We determined the effects of seizure-onset zone, electrode location, and patient-age upon gamma-augmentation elicited by an auditory-naming task. RESULTS Gamma-augmentation was less frequently elicited within seizure-onset sites compared to other sites. Regardless of age, gamma-augmentation most often involved the 80–100 Hz frequency band. Gamma-augmentation initially involved bilateral superior-temporal regions, followed by left-side dominant involvement in the middle-temporal, medial-temporal, inferior-frontal, dorsolateral-premotor, and medial-frontal regions and concluded with bilateral inferior-Rolandic involvement. Compared to younger patients, those older than 10 years had a larger proportion of left dorsolateral-premotor and right inferior-frontal sites showing gamma-augmentation. The incidence of a post-operative language deficit requiring speech therapy was predicted by the number of resected sites with gamma-augmentation in the superior-temporal, inferior-frontal, dorsolateral-premotor, and inferior-Rolandic regions of the left hemisphere assumed to contain essential language function (r2=0.59; p=0.001; odds ratio=6.04 [95% confidence-interval: 2.26 to 16.15]). CONCLUSIONS Auditory-language-related gamma-augmentation can provide additional information useful to localize the primary language areas. SIGNIFICANCE These results derived from a large sample of patients support the utility of auditory-language-related gamma-augmentation in presurgical evaluation. PMID:23141882

Optogenetically induced spatiotemporal gamma oscillations and neuronal spiking activity in primate motor cortex.

PubMed

Lu, Yao; Truccolo, Wilson; Wagner, Fabien B; Vargas-Irwin, Carlos E; Ozden, Ilker; Zimmermann, Jonas B; May, Travis; Agha, Naubahar S; Wang, Jing; Nurmikko, Arto V

2015-06-01

Transient gamma-band (40-80 Hz) spatiotemporal patterns are hypothesized to play important roles in cortical function. Here we report the direct observation of gamma oscillations as spatiotemporal waves induced by targeted optogenetic stimulation, recorded by intracortical multichannel extracellular techniques in macaque monkeys during their awake resting states. Microelectrode arrays integrating an optical fiber at their center were chronically implanted in primary motor (M1) and ventral premotor (PMv) cortices of two subjects. Targeted brain tissue was transduced with the red-shifted opsin C1V1(T/T). Constant (1-s square pulses) and ramp stimulation induced narrowband gamma oscillations during awake resting states. Recordings across 95 microelectrodes (4 × 4-mm array) enabled us to track the transient gamma spatiotemporal patterns manifested, e.g., as concentric expanding and spiral waves. Gamma oscillations were induced well beyond the light stimulation volume, via network interactions at distal electrode sites, depending on optical power. Despite stimulation-related modulation in spiking rates, neuronal spiking remained highly asynchronous during induced gamma oscillations. In one subject we examined stimulation effects during preparation and execution of a motor task and observed that movement execution largely attenuated optically induced gamma oscillations. Our findings demonstrate that, beyond previously reported induced gamma activity under periodic drive, a prolonged constant stimulus above a certain threshold may carry primate motor cortex network dynamics into gamma oscillations, likely via a Hopf bifurcation. More broadly, the experimental capability in combining microelectrode array recordings and optogenetic stimulation provides an important approach for probing spatiotemporal dynamics in primate cortical networks during various physiological and behavioral conditions.

Optogenetically induced spatiotemporal gamma oscillations and neuronal spiking activity in primate motor cortex

PubMed Central

Lu, Yao; Truccolo, Wilson; Wagner, Fabien B.; Vargas-Irwin, Carlos E.; Ozden, Ilker; Zimmermann, Jonas B.; May, Travis; Agha, Naubahar S.; Wang, Jing

2015-01-01

Transient gamma-band (40–80 Hz) spatiotemporal patterns are hypothesized to play important roles in cortical function. Here we report the direct observation of gamma oscillations as spatiotemporal waves induced by targeted optogenetic stimulation, recorded by intracortical multichannel extracellular techniques in macaque monkeys during their awake resting states. Microelectrode arrays integrating an optical fiber at their center were chronically implanted in primary motor (M1) and ventral premotor (PMv) cortices of two subjects. Targeted brain tissue was transduced with the red-shifted opsin C1V1(T/T). Constant (1-s square pulses) and ramp stimulation induced narrowband gamma oscillations during awake resting states. Recordings across 95 microelectrodes (4 × 4-mm array) enabled us to track the transient gamma spatiotemporal patterns manifested, e.g., as concentric expanding and spiral waves. Gamma oscillations were induced well beyond the light stimulation volume, via network interactions at distal electrode sites, depending on optical power. Despite stimulation-related modulation in spiking rates, neuronal spiking remained highly asynchronous during induced gamma oscillations. In one subject we examined stimulation effects during preparation and execution of a motor task and observed that movement execution largely attenuated optically induced gamma oscillations. Our findings demonstrate that, beyond previously reported induced gamma activity under periodic drive, a prolonged constant stimulus above a certain threshold may carry primate motor cortex network dynamics into gamma oscillations, likely via a Hopf bifurcation. More broadly, the experimental capability in combining microelectrode array recordings and optogenetic stimulation provides an important approach for probing spatiotemporal dynamics in primate cortical networks during various physiological and behavioral conditions. PMID:25761956

Sphingosine kinase inhibitor suppresses IL-18-induced interferon-gamma production through inhibition of p38 MAPK activation in human NK cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheon, Soyoung; Song, Seok Bean; Jung, Minkyung

2008-09-12

Natural killer (NK) cells play an important role in the innate immune response. Interleukin-18 (IL-18) is a well-known interferon-gamma (IFN-{gamma} inducing factor, which stimulates immune response in NK and T cells. Sphingosine kinase (SPHK) catalyzes the formation of sphingosine 1-phosphate (S1P), which acts as a second messenger to function as an anti-apoptotic factor and proliferation stimulator of immune cells. In this study, to elucidate whether SPHK is involved in IL-18-induced IFN-{gamma} production, we measured IL-18-induced IFN-{gamma} production after pre-treatment with SPHK inhibitor (SKI) in NK-92MI cells. We found that IL-18-induced IFN-{gamma} expression was blocked by SKI pre-treatment in both mRNAmore » and protein levels. In addition, the increased IFN-{gamma} production by stimulation with IL-18 is mediated through both SPHK and p38 MAPK. To determine the upstream signals of SKI and p38 MAPK in IL-18-induced IFN-{gamma} production, phosphorylation levels of p38 MAPK was measured after SKI pre-treatment. As a result, inhibition of SPHK by SKI blocked phosphorylation of p38 MAPK, showing that SPHK activation by IL-18 is an upstream signal of p38 MAPK activation. Inhibition of SPHK by SKI also inhibited IL-18-induced IFN-{gamma} production in human primary NK cells. In conclusion, SPHK activation is an essential factor for IL-18-induced IFN-{gamma} production via p38 MAPK.« less

Molecular cloning, characterization and expression analysis of PPAR gamma in the orange-spotted grouper (Epinephelus coioides) after the Vibrio alginolyticus challenge.

PubMed

Luo, Shengwei; Huang, Youhua; Xie, Fuxing; Huang, Xiaohong; Liu, Yuan; Wang, Weina; Qin, Qiwei

2015-04-01

PPAR gamma was a key nuclear receptor, playing an important role in the immune defense and the anti-inflammatory mechanism. In this study, the full-length PPAR gamma (EcPPAR gamma) was obtained, containing a 5'UTR of 133 bp, an ORF of 1602 bp and a 3'UTR of 26 bp besides the poly (A) tail. The EcPPAR gamma gene encoded a protein of 533 amino acids with an estimated molecular mass of 60.02 KDa and a predicted isoelectric point (pI) of 6.26. The deduced amino acid sequence showed that EcPPAR gamma consisted of the conserved residues and the domains known to be critical for the PPAR gamma function. The quantitative real-time PCR analysis revealed that EcPPAR gamma transcript was expressed in all the examined tissue, while the strong expression was observed in intestine, followed by the expression in liver, gill, spleen heart, kidney and muscle. Vibrio challenge could stimulate the inflammatory response in grouper and induce a sharp increase of pro-inflammatory cytokines expression, lipid peroxidation and DNA damage, while the up-regulation of vibrio-induced inflammation could also increase the non-specific immune defense. The groupers challenged with Vibrio alginolyticus showed a sharp increase of EcPPAR gamma transcript in immune tissues. Subcellular localization analysis revealed that EcPPAR gamma was distributed in the nucleus. Furthermore, overexpression of EcPPAR gamma could down-regulated the expression of IL1b, IL6, TNF1 and TNF2. In addition, the administration of PPAR gamma antagonist, GW9662, could up-regulate the expression of pro-inflammatory genes, including IL1b, IL6, TNF1 and TNF2. Together, these results indicated that EcPPAR gamma serving as a negative regulator of pro-inflammatory cytokines may play an important role in the immune defense against vibrio-induced inflammation in grouper. Copyright © 2015 Elsevier Ltd. All rights reserved.

Self-absorption theory applied to rocket measurements of the nitric oxide (1, 0) gamma band in the daytime thermosphere

NASA Technical Reports Server (NTRS)

Eparvier, F. G.; Barth, C. A.

1992-01-01

Observations of the UV fluorescent emissions of the NO (1, 0) and (0, 1) gamma bands in the lower-thermospheric dayglow, made with a sounding rocket launched on March 7, 1989 from Poker Flat, Alaska, were analyzed. The resonant (1, 0) gamma band was found to be attenuated below an altitude of about 120 km. A self-absorption model based on Holstein transmission functions was developed for the resonant (1, 0) gamma band under varying conditions of slant column density and temperature and was applied for the conditions of the rocket flight. The results of the model agreed with the measured attenuation of the band, indicating the necessity of including self-absorption theory in the analysis of satellite and rocket limb data of NO.

Neutron and gamma-ray dose-rates from the Little Boy replica

DOE Office of Scientific and Technical Information (OSTI.GOV)

Plassmann, E.A.; Pederson, R.A.

1984-01-01

We report dose-rate information obtained at many locations in the near vicinity of, and at distances out to 0.64 km from, the Little Boy replica while it was operated as a critical assembly. The measurements were made with modified conventional dosimetry instruments that used an Anderson-Braun detector for neutrons and a Geiger-Mueller tube for gamma rays with suitable electronic modules to count particle-induced pulses. Thermoluminescent dosimetry methods provide corroborative data. Our analysis gives estimates of both neutron and gamma-ray relaxation lengths in air for comparison with earlier calculations. We also show the neutron-to-gamma-ray dose ratio as a function of distancemore » from the replica. Current experiments and further data analysis will refine these results. 7 references, 8 figures.« less

A compound scattering pdf for the ultrasonic echo envelope and its relationship to K and Nakagami distributions.

PubMed

Shankar, P Mohana

2003-03-01

A compound probability density function (pdf) is presented to describe the envelope of the backscattered echo from tissue. This pdf allows local and global variation in scattering cross sections in tissue. The ultrasonic backscattering cross sections are assumed to be gamma distributed. The gamma distribution also is used to model the randomness in the average cross sections. This gamma-gamma model results in the compound scattering pdf for the envelope. The relationship of this compound pdf to the Rayleigh, K, and Nakagami distributions is explored through an analysis of the signal-to-noise ratio of the envelopes and random number simulations. The three parameter compound pdf appears to be flexible enough to represent envelope statistics giving rise to Rayleigh, K, and Nakagami distributions.

Role of adapter function in oncoprotein-mediated activation of NF-kappaB. Human T-cell leukemia virus type I Tax interacts directly with IkappaB kinase gamma.

PubMed

Jin, D Y; Giordano, V; Kibler, K V; Nakano, H; Jeang, K T

1999-06-18

Mechanisms by which the human T-cell leukemia virus type I Tax oncoprotein activates NF-kappaB remain incompletely understood. Although others have described an interaction between Tax and a holo-IkappaB kinase (IKK) complex, the exact details of protein-protein contact are not fully defined. Here we show that Tax binds to neither IKK-alpha nor IKK-beta but instead complexes directly with IKK-gamma, a newly characterized component of the IKK complex. This direct interaction with IKK-gamma correlates with Tax-induced IkappaB-alpha phosphorylation and NF-kappaB activation. Thus, our findings establish IKK-gamma as a key molecule for adapting an oncoprotein-specific signaling to IKK-alpha and IKK-beta.

Progress on the Europium Neutron-Capture Study using DANCE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Agvaanluvsan, U; Becker, J A; Macri, R A

2006-09-05

The accurate measurement of neutron-capture cross sections of the Eu isotopes is important for many reasons including nuclear astrophysics and nuclear diagnostics. Neutron capture excitation functions of {sup 151,153}Eu targets were measured recently using a 4{pi} {gamma}-ray calorimeter array DANCE located at the Los Alamos Neutron Science Center for E{sub n} = 0.1-100 keV. The progress on the data analysis efforts is given in the present paper. The {gamma}-ray multiplicity distributions for the Eu targets and Be backing are significantly different. The {gamma}-ray multiplicity distribution is found to be the same for different neutron energies for both {sup 151}Eu andmore » {sup 153}Eu. The statistical simulation to model the {gamma}-ray decay cascade is summarized.« less

Fast neutron-gamma discrimination on neutron emission profile measurement on JT-60U

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ishii, K.; Okamoto, A.; Kitajima, S.

2010-10-15

A digital signal processing (DSP) system is applied to stilbene scintillation detectors of the multichannel neutron emission profile monitor in JT-60U. Automatic analysis of the neutron-{gamma} pulse shape discrimination is a key issue to diminish the processing time in the DSP system, and it has been applied using the two-dimensional (2D) map. Linear discriminant function is used to determine the dividing line between neutron events and {gamma}-ray events on a 2D map. In order to verify the validity of the dividing line determination, the pulse shape discrimination quality is evaluated. As a result, the {gamma}-ray contamination in most of themore » beam heating phase was negligible compared with the statistical error with 10 ms time resolution.« less

Spectral determinations for discrete sources with EGRET

NASA Technical Reports Server (NTRS)

Hughes, E. B.; Nolan, P. L.

1990-01-01

The ability of the EGRET (Energetic Gamma-Ray Experimental Telescope) to determine the spectral parameters of point sources in 14-day exposures, as planned for the initial survey phase of the GRO (Gamma Ray Observatory) mission, is explored by numerical simulation. Results are given for both galactic and extragalactic objects as a function of source strength and for representative levels of diffuse background emission.

Documentation of the data analysis system for the gamma ray monitor aboard OSO-H

NASA Technical Reports Server (NTRS)

Croteau, S.; Buck, A.; Higbie, P.; Kantauskis, J.; Foss, S.; Chupp, D.; Forrest, D. J.; Suri, A.; Gleske, I.

1973-01-01

The programming system is presented which was developed to prepare the data from the gamma ray monitor on OSO-7 for scientific analysis. The detector, data, and objectives are described in detail. Programs presented include; FEEDER, PASS-1, CAL1, CAL2, PASS-3, Van Allen Belt Predict Program, Computation Center Plot Routine, and Response Function Programs.

Organocatalytic sequential alpha-amination-Horner-Wadsworth-Emmons olefination of aldehydes: enantioselective synthesis of gamma-amino-alpha,beta-unsaturated esters.

PubMed

Kotkar, Shriram P; Chavan, Vilas B; Sudalai, Arumugam

2007-03-15

A novel and highly enantioselective method for the synthesis of gamma-amino-alpha,beta-unsaturated esters via tandem alpha-amination-Horner-Wadsworth-Emmons (HWE) olefination of aldehydes is described. The one-pot assembly has been demonstrated for the construction of functionalized chiral 2-pyrrolidones, subunits present in several alkaloids. [structure: see text

Metabolic modulation of neuronal gamma-band oscillations.

PubMed

Vodovozov, Wadim; Schneider, Justus; Elzoheiry, Shehabeldin; Hollnagel, Jan-Oliver; Lewen, Andrea; Kann, Oliver

2018-05-28

Gamma oscillations (30-100 Hz) represent a physiological fast brain rhythm that occurs in many cortex areas in awake mammals, including humans. They associate with sensory perception, voluntary movement, and memory formation and require precise synaptic transmission between excitatory glutamatergic neurons and inhibitory GABAergic interneurons such as parvalbumin-positive basket cells. Notably, gamma oscillations are exquisitely sensitive to shortage in glucose and oxygen supply (metabolic stress), with devastating consequences for higher cognitive functions. Herein, we explored the robustness of gamma oscillations against changes in the availability of alternative energy substrates and amino acids, which is partially regulated by glial cells such as astrocytes. We used organotypic slice cultures of the rat hippocampus expressing acetylcholine-induced persistent gamma oscillations under normoxic recording conditions (20% oxygen fraction). Our main findings are (1) partial substitution of glucose with pyruvate and the ketone body β-hydroxybutyrate increases the frequency of gamma oscillations, even at different stages of neuronal tissue development. (2) Supplementation with the astrocytic neurotransmitter precursor glutamine has no effect on the properties of gamma oscillations. (3) Supplementation with glycine increases power, frequency, and inner coherence of gamma oscillations in a dose-dependent manner. (4) During these treatments switches to other frequency bands or pathological network states such as neural burst firing or synchronized epileptic activity are absent. Our study indicates that cholinergic gamma oscillations show general robustness against these changes in nutrient and amino acid composition of the cerebrospinal fluid; however, modulation of their properties may impact on cortical information processing under physiological and pathophysiological conditions.

Gamma-Ray Emission from Galaxy Clusters : DARK MATTER AND COSMIC-RAYS

NASA Astrophysics Data System (ADS)

Pinzke, Anders

The quest for the first detection of a galaxy cluster in the high energy gamma-ray regime is ongoing, and even though clusters are observed in several other wave-bands, there is still no firm detection in gamma-rays. To complement the observational efforts we estimate the gamma-ray contributions from both annihilating dark matter and cosmic-ray (CR) proton as well as CR electron induced emission. Using high-resolution simulations of galaxy clusters, we find a universal concave shaped CR proton spectrum independent of the simulated galaxy cluster. Specifically, the gamma-ray spectra from decaying neutral pions, which are produced by CR protons, dominate the cluster emission. Furthermore, based on our derived flux and luminosity functions, we identify the galaxy clusters with the brightest galaxy clusters in gamma-rays. While this emission is challenging to detect using the Fermi satellite, major observations with Cherenkov telescopes in the near future may put important constraints on the CR physics in clusters. To extend these predictions, we use a dark matter model that fits the recent electron and positron data from Fermi, PAMELA, and H.E.S.S. with remarkable precision, and make predictions about the expected gamma-ray flux from nearby clusters. In order to remain consistent with the EGRET upper limit on the gamma-ray emission from Virgo, we constrain the minimum mass of substructures for cold dark matter halos. In addition, we find comparable levels of gamma-ray emission from CR interactions and dark matter annihilations without Sommerfeld enhancement.

GammaLib and ctools. A software framework for the analysis of astronomical gamma-ray data

NASA Astrophysics Data System (ADS)

Knödlseder, J.; Mayer, M.; Deil, C.; Cayrou, J.-B.; Owen, E.; Kelley-Hoskins, N.; Lu, C.-C.; Buehler, R.; Forest, F.; Louge, T.; Siejkowski, H.; Kosack, K.; Gerard, L.; Schulz, A.; Martin, P.; Sanchez, D.; Ohm, S.; Hassan, T.; Brau-Nogué, S.

2016-08-01

The field of gamma-ray astronomy has seen important progress during the last decade, yet to date no common software framework has been developed for the scientific analysis of gamma-ray telescope data. We propose to fill this gap by means of the GammaLib software, a generic library that we have developed to support the analysis of gamma-ray event data. GammaLib was written in C++ and all functionality is available in Python through an extension module. Based on this framework we have developed the ctools software package, a suite of software tools that enables flexible workflows to be built for the analysis of Imaging Air Cherenkov Telescope event data. The ctools are inspired by science analysis software available for existing high-energy astronomy instruments, and they follow the modular ftools model developed by the High Energy Astrophysics Science Archive Research Center. The ctools were written in Python and C++, and can be either used from the command line via shell scripts or directly from Python. In this paper we present the GammaLib and ctools software versions 1.0 that were released at the end of 2015. GammaLib and ctools are ready for the science analysis of Imaging Air Cherenkov Telescope event data, and also support the analysis of Fermi-LAT data and the exploitation of the COMPTEL legacy data archive. We propose using ctools as the science tools software for the Cherenkov Telescope Array Observatory.

Free radicals properties of gamma-irradiated penicillin-derived antibiotics: piperacillin, ampicillin, and crystalline penicillin.

PubMed

Wilczyński, Sławomir; Pilawa, Barbara; Koprowski, Robert; Wróbel, Zygmunt; Ptaszkiewicz, Marta; Swakoń, Jan; Olko, Paweł

2014-03-01

The aim of this work was to determine the concentrations and properties of free radicals in piperacillin, ampicillin, and crystalline penicillin after gamma irradiation. The radicals were studied by electron paramagnetic resonance (EPR) spectroscopy using an X-band spectrometer (9.3 GHz). Gamma irradiation was performed at a dose of 25 kGy. One- and two-exponential functions were fitted to the experimental data, in order to assess the influence of the antibiotics' storage time on the measured EPR lines. After gamma irradiation, complex EPR lines were recorded confirming the presence of a large number of free radicals formed during the irradiation. For all tested antibiotics, concentrations of free radicals and parameters of EPR spectra changed with storage time. The results obtained demonstrate that concentration of free radicals and other spectroscopic parameters can be used to select the optimal parameters of radiation sterilization of β-lactam antibiotics. The most important parameters are the constants τ (τ (1(A),(I)) and τ (2(A),(I))) and K (K (0(A),(I)), K (1(A),(I)), K (2(A),(I))) of the exponential functions that describe free radicals decay during samples storage.

Synchronization Dynamics in Response to Plaid Stimuli in Monkey V1

PubMed Central

Lima, Bruss; Singer, Wolf; Chen, Nan-Hui

2010-01-01

Gamma synchronization has generally been associated with grouping processes in the visual system. Here, we examine in monkey V1 whether gamma oscillations play a functional role in segmenting surfaces of plaid stimuli. Local field potentials (LFPs) and spiking activity were recorded simultaneously from multiple sites in the opercular and calcarine regions while the monkeys were presented with sequences of single and superimposed components of plaid stimuli. In accord with the previous studies, responses to the single components (gratings) exhibited strong and sustained gamma-band oscillations (30–65 Hz). The superposition of the second component, however, led to profound changes in the temporal structure of the responses, characterized by a drastic reduction of gamma oscillations in the spiking activity and systematic shifts to higher frequencies in the LFP (∼10% increase). Comparisons between cerebral hemispheres and across monkeys revealed robust subject-specific spectral signatures. A possible interpretation of our results may be that single gratings induce strong cooperative interactions among populations of cells that share similar response properties, whereas plaids lead to competition. Overall, our results suggest that the functional architecture of the cortex is a major determinant of the neuronal synchronization dynamics in V1. PMID:19812238

Solid state microelectronics tolerant to radiation and high temperature. [JFET thick film hybrids

NASA Technical Reports Server (NTRS)

Draper, B. L.; Palmer, D. W.

1981-01-01

The 300 C electronics technology based on JFET thick film hybrids was tested up to 10 to the 9th power rad gamma (Si) and 10 to the 15th power neutrons/sq cm. Circuits and individual components from this technology all survived this total dose although some devices required 1 hour of annealing at 200 or 300 C to regain functionality. This technology used with real time annealing should function to levels greater than 10 to the 10th power rad gamma and 10 to the 16th power n/sq cm.

Using support vector machine to predict beta- and gamma-turns in proteins.

PubMed

Hu, Xiuzhen; Li, Qianzhong

2008-09-01

By using the composite vector with increment of diversity, position conservation scoring function, and predictive secondary structures to express the information of sequence, a support vector machine (SVM) algorithm for predicting beta- and gamma-turns in the proteins is proposed. The 426 and 320 nonhomologous protein chains described by Guruprasad and Rajkumar (Guruprasad and Rajkumar J. Biosci 2000, 25,143) are used for training and testing the predictive model of the beta- and gamma-turns, respectively. The overall prediction accuracy and the Matthews correlation coefficient in 7-fold cross-validation are 79.8% and 0.47, respectively, for the beta-turns. The overall prediction accuracy in 5-fold cross-validation is 61.0% for the gamma-turns. These results are significantly higher than the other algorithms in the prediction of beta- and gamma-turns using the same datasets. In addition, the 547 and 823 nonhomologous protein chains described by Fuchs and Alix (Fuchs and Alix Proteins: Struct Funct Bioinform 2005, 59, 828) are used for training and testing the predictive model of the beta- and gamma-turns, and better results are obtained. This algorithm may be helpful to improve the performance of protein turns' prediction. To ensure the ability of the SVM method to correctly classify beta-turn and non-beta-turn (gamma-turn and non-gamma-turn), the receiver operating characteristic threshold independent measure curves are provided. (c) 2008 Wiley Periodicals, Inc.

X-Ray Spectra of Young Pulsars and Their Wind Nebulae: Dependence on Spin-Down Energy Loss Rate

NASA Technical Reports Server (NTRS)

Gotthelf, E. V.

2003-01-01

An observational model is presented for the spectra of young rotation-powered pulsars and their nebulae based on a study of nine bright Crab-like pulsar systems observed with the Chandra X-ray observatory. A significant correlation is discovered between the X-ray spectra of these pulsars and that of their associated pulsar wind nebulae, both of which are observed to be a function of the spin-down energy loss rate, E. The 2-10 keV spectra of these objects are well characterized by an absorbed power-law model with photon indices, Gamma, in the range of 0.6 < Gamma (sub PSR) < 2.1 and 1.3 < Gamma(sub PWN) < 2.3, for the pulsars and their nebulae, respectively. A linear regression fit relating these two sets of indexes yields Gamma(sub PWN) = 0.91 +/- 0.18 + (0.66 +/- 0.11) Gamma (sub PSR), with a correlation coefficient of r = 0.97. The spectra of these pulsars are found to steepen as Gamma = Gamma(sub max) + alpha E (exp -1/2), with Gamma(sub max) providing an observational limit on the spectral slopes of young rotation-powered pulsars. These results reveal basic properties of young pulsar systems, allow new observational constraints on models of pulsar wind emission, and provide a means of predicting the energetics of pulsars lacking detected pulsations.

Areas V1 and V2 show microsaccade-related 3-4-Hz covariation in gamma power and frequency.

PubMed

Lowet, E; Roberts, M J; Bosman, C A; Fries, P; De Weerd, P

2016-05-01

Neuronal gamma-band synchronization (25-80 Hz) in visual cortex appears sustained and stable during prolonged visual stimulation when investigated with conventional averages across trials. However, recent studies in macaque visual cortex have used single-trial analyses to show that both power and frequency of gamma oscillations exhibit substantial moment-by-moment variation. This has raised the question of whether these apparently random variations might limit the functional role of gamma-band synchronization for neural processing. Here, we studied the moment-by-moment variation in gamma oscillation power and frequency, as well as inter-areal gamma synchronization, by simultaneously recording local field potentials in V1 and V2 of two macaque monkeys. We additionally analyzed electrocorticographic V1 data from a third monkey. Our analyses confirm that gamma-band synchronization is not stationary and sustained but undergoes moment-by-moment variations in power and frequency. However, those variations are neither random and nor a possible obstacle to neural communication. Instead, the gamma power and frequency variations are highly structured, shared between areas and shaped by a microsaccade-related 3-4-Hz theta rhythm. Our findings provide experimental support for the suggestion that cross-frequency coupling might structure and facilitate the information flow between brain regions. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Factorials of real negative and imaginary numbers - A new perspective.

PubMed

Thukral, Ashwani K

2014-01-01

Presently, factorials of real negative numbers and imaginary numbers, except for zero and negative integers are interpolated using the Euler's gamma function. In the present paper, the concept of factorials has been generalised as applicable to real and imaginary numbers, and multifactorials. New functions based on Euler's factorial function have been proposed for the factorials of real negative and imaginary numbers. As per the present concept, the factorials of real negative numbers, are complex numbers. The factorials of real negative integers have their imaginary part equal to zero, thus are real numbers. Similarly, the factorials of imaginary numbers are complex numbers. The moduli of the complex factorials of real negative numbers, and imaginary numbers are equal to their respective real positive number factorials. Fractional factorials and multifactorials have been defined in a new perspective. The proposed concept has also been extended to Euler's gamma function for real negative numbers and imaginary numbers, and beta function.

Adaptation and impairment of DNA repair function in pollen of Betula verrucosa and seeds of Oenothera biennis from differently radionuclide-contaminated sites of Chernobyl.

PubMed

Boubriak, I I; Grodzinsky, D M; Polischuk, V P; Naumenko, V D; Gushcha, N P; Micheev, A N; McCready, S J; Osborne, D J

2008-01-01

The plants that have remained in the contaminated areas around Chernobyl since 1986 encapsulate the effects of radiation. Such plants are chronically exposed to radionuclides that they have accumulated internally as well as to alpha-, beta- and gamma-emitting radionuclides from external sources and from the soil. This radiation leads to genetic damage that can be countered by DNA repair systems. The objective of this study is to follow DNA repair and adaptation in haploid cells (birch pollen) and diploid cells (seed embryos of the evening primrose) from plants that have been growing in situ in different radionuclide fall-out sites in monitored regions surrounding the Chernobyl explosion of 1986. Radionuclide levels in soil were detected using gamma-spectroscopy and radiochemistry. DNA repair assays included measurement of unscheduled DNA synthesis, electrophoretic determination of single-strand DNA breaks and image analysis of rDNA repeats after repair intervals. Nucleosome levels were established using an ELISA kit. Birch pollen collected in 1987 failed to perform unscheduled DNA synthesis, but pollen at gamma/beta-emitter sites has now recovered this ability. At a site with high levels of combined alpha- and gamma/beta-emitters, pollen still exhibits hidden damage, as shown by reduced unscheduled DNA synthesis and failure to repair lesions in rDNA repeats properly. Evening primrose seed embryos generated on plants at the same gamma/beta-emitter sites now show an improved DNA repair capacity and ability to germinate under abiotic stresses (salinity and accelerated ageing). Again those from combined alpha- and gamma/beta-contaminated site do not show this improvement. Chronic irradiation at gamma/beta-emitter sites has provided opportunities for plant cells (both pollen and embryo cells) to adapt to ionizing irradiation and other environmental stresses. This may be explained by facilitation of DNA repair function.

MeV gamma-ray observation with a well-defined point spread function based on electron tracking

NASA Astrophysics Data System (ADS)

Takada, A.; Tanimori, T.; Kubo, H.; Mizumoto, T.; Mizumura, Y.; Komura, S.; Kishimoto, T.; Takemura, T.; Yoshikawa, K.; Nakamasu, Y.; Matsuoka, Y.; Oda, M.; Miyamoto, S.; Sonoda, S.; Tomono, D.; Miuchi, K.; Kurosawa, S.; Sawano, T.

2016-07-01

The field of MeV gamma-ray astronomy has not opened up until recently owing to imaging difficulties. Compton telescopes and coded-aperture imaging cameras are used as conventional MeV gamma-ray telescopes; however their observations are obstructed by huge background, leading to uncertainty of the point spread function (PSF). Conventional MeV gamma-ray telescopes imaging utilize optimizing algorithms such as the ML-EM method, making it difficult to define the correct PSF, which is the uncertainty of a gamma-ray image on the celestial sphere. Recently, we have defined and evaluated the PSF of an electron-tracking Compton camera (ETCC) and a conventional Compton telescope, and thereby obtained an important result: The PSF strongly depends on the precision of the recoil direction of electron (scatter plane deviation, SPD) and is not equal to the angular resolution measure (ARM). Now, we are constructing a 30 cm-cubic ETCC for a second balloon experiment, Sub-MeV gamma ray Imaging Loaded-on-balloon Experiment: SMILE-II. The current ETCC has an effective area of 1 cm2 at 300 keV, a PSF of 10° at FWHM for 662 keV, and a large field of view of 3 sr. We will upgrade this ETCC to have an effective area of several cm2 and a PSF of 5° using a CF4-based gas. Using the upgraded ETCC, our observation plan for SMILE-II is to map of the electron-positron annihilation line and the 1.8 MeV line from 26Al. In this paper, we will report on the current performance of the ETCC and on our observation plan.

Illustration of microphysical processes in Amazonian deep convective clouds in the gamma phase space: introduction and potential applications

NASA Astrophysics Data System (ADS)

Cecchini, Micael A.; Machado, Luiz A. T.; Wendisch, Manfred; Costa, Anja; Krämer, Martina; Andreae, Meinrat O.; Afchine, Armin; Albrecht, Rachel I.; Artaxo, Paulo; Borrmann, Stephan; Fütterer, Daniel; Klimach, Thomas; Mahnke, Christoph; Martin, Scot T.; Minikin, Andreas; Molleker, Sergej; Pardo, Lianet H.; Pöhlker, Christopher; Pöhlker, Mira L.; Pöschl, Ulrich; Rosenfeld, Daniel; Weinzierl, Bernadett

2017-12-01

The behavior of tropical clouds remains a major open scientific question, resulting in poor representation by models. One challenge is to realistically reproduce cloud droplet size distributions (DSDs) and their evolution over time and space. Many applications, not limited to models, use the gamma function to represent DSDs. However, even though the statistical characteristics of the gamma parameters have been widely studied, there is almost no study dedicated to understanding the phase space of this function and the associated physics. This phase space can be defined by the three parameters that define the DSD intercept, shape, and curvature. Gamma phase space may provide a common framework for parameterizations and intercomparisons. Here, we introduce the phase space approach and its characteristics, focusing on warm-phase microphysical cloud properties and the transition to the mixed-phase layer. We show that trajectories in this phase space can represent DSD evolution and can be related to growth processes. Condensational and collisional growth may be interpreted as pseudo-forces that induce displacements in opposite directions within the phase space. The actually observed movements in the phase space are a result of the combination of such pseudo-forces. Additionally, aerosol effects can be evaluated given their significant impact on DSDs. The DSDs associated with liquid droplets that favor cloud glaciation can be delimited in the phase space, which can help models to adequately predict the transition to the mixed phase. We also consider possible ways to constrain the DSD in two-moment bulk microphysics schemes, in which the relative dispersion parameter of the DSD can play a significant role. Overall, the gamma phase space approach can be an invaluable tool for studying cloud microphysical evolution and can be readily applied in many scenarios that rely on gamma DSDs.

Alterations in interhemispheric gamma-band connectivity are related to the emergence of auditory verbal hallucinations in healthy subjects during NMDA-receptor blockade.

PubMed

Thiebes, Stephanie; Steinmann, Saskia; Curic, Stjepan; Polomac, Nenad; Andreou, Christina; Eichler, Iris-Carola; Eichler, Lars; Zöllner, Christian; Gallinat, Jürgen; Leicht, Gregor; Mulert, Christoph

2018-06-01

Auditory verbal hallucinations (AVH) are a common positive symptom of schizophrenia. Excitatory-to-inhibitory (E/I) imbalance related to disturbed N-methyl-D-aspartate receptor (NMDAR) functioning has been suggested as a possible mechanism underlying altered connectivity and AVH in schizophrenia. The current study examined the effects of ketamine, a NMDAR antagonist, on glutamate-related mechanisms underlying interhemispheric gamma-band connectivity, conscious auditory perception during dichotic listening (DL), and the emergence of auditory verbal distortions and hallucinations (AVD/AVH) in healthy volunteers. In a single-blind, pseudo-randomized, placebo-controlled crossover design, nineteen male, right-handed volunteers were measured using 64 channel electroencephalography (EEG). Psychopathology was assessed with the PANSS interview and the 5D-ASC questionnaire, including a subscale to detect auditory alterations with regard to AVD/AVH (AUA-AVD/AVH). Interhemispheric connectivity analysis was performed using eLORETA source estimation and lagged phase synchronization (LPS) in the gamma-band range (30-100 Hz). Ketamine induced positive symptoms such as hallucinations in a subgroup of healthy subjects. In addition, interhemispheric gamma-band connectivity was found to be altered under ketamine compared to placebo, and subjects with AUA-AVD/AVH under ketamine showed significantly higher interhemispheric gamma-band connectivity than subjects without AUA-AVD/AVH. These findings demonstrate a relationship between NMDAR functioning, interhemispheric connectivity in the gamma-band frequency range between bilateral auditory cortices and the emergence of AVD/AVH in healthy subjects. The result is in accordance with the interhemispheric miscommunication hypothesis of AVH and argues for a possible role of glutamate in AVH in schizophrenia.

Analytical results for the statistical distribution related to a memoryless deterministic walk: dimensionality effect and mean-field models.

PubMed

Terçariol, César Augusto Sangaletti; Martinez, Alexandre Souto

2005-08-01

Consider a medium characterized by N points whose coordinates are randomly generated by a uniform distribution along the edges of a unitary d-dimensional hypercube. A walker leaves from each point of this disordered medium and moves according to the deterministic rule to go to the nearest point which has not been visited in the preceding mu steps (deterministic tourist walk). Each trajectory generated by this dynamics has an initial nonperiodic part of t steps (transient) and a final periodic part of p steps (attractor). The neighborhood rank probabilities are parametrized by the normalized incomplete beta function Id= I1/4 [1/2, (d+1) /2] . The joint distribution S(N) (mu,d) (t,p) is relevant, and the marginal distributions previously studied are particular cases. We show that, for the memory-less deterministic tourist walk in the euclidean space, this distribution is Sinfinity(1,d) (t,p) = [Gamma (1+ I(-1)(d)) (t+ I(-1)(d) ) /Gamma(t+p+ I(-1)(d)) ] delta(p,2), where t=0, 1,2, ... infinity, Gamma(z) is the gamma function and delta(i,j) is the Kronecker delta. The mean-field models are the random link models, which correspond to d-->infinity, and the random map model which, even for mu=0 , presents nontrivial cycle distribution [ S(N)(0,rm) (p) proportional to p(-1) ] : S(N)(0,rm) (t,p) =Gamma(N)/ {Gamma[N+1- (t+p) ] N( t+p)}. The fundamental quantities are the number of explored points n(e)=t+p and Id. Although the obtained distributions are simple, they do not follow straightforwardly and they have been validated by numerical experiments.

The integral line-beam method for gamma skyshine analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shultis, J.K.; Faw, R.E.; Bassett, M.S.

1991-03-01

This paper presents a refinement of a simplified method, based on line-beam response functions, for performing skyshine calculations for shielded and collimated gamma-ray sources. New coefficients for an empirical fit to the line-beam response function are provided and a prescription for making the response function continuous in energy and emission direction is introduced. For a shielded source, exponential attenuation and a buildup factor correction for scattered photons in the shield are used. Results of the new integral line-beam method of calculation are compared to a variety of benchmark experimental data and calculations and are found to give generally excellent agreementmore » at a small fraction of the computational expense required by other skyshine methods.« less

Hippocampal-prefrontal theta-gamma coupling during performance of a spatial working memory task.

PubMed

Tamura, Makoto; Spellman, Timothy J; Rosen, Andrew M; Gogos, Joseph A; Gordon, Joshua A

2017-12-19

Cross-frequency coupling supports the organization of brain rhythms and is present during a range of cognitive functions. However, little is known about whether and how long-range cross-frequency coupling across distant brain regions subserves working memory. Here we report that theta-slow gamma coupling between the hippocampus and medial prefrontal cortex (mPFC) is augmented in a genetic mouse model of cognitive dysfunction. This increased cross-frequency coupling is observed specifically when the mice successfully perform a spatial working memory task. In wild-type mice, increasing task difficulty by introducing a long delay or by optogenetically interfering with encoding, also increases theta-gamma coupling during correct trials. Finally, epochs of high hippocampal theta-prefrontal slow gamma coupling are associated with increased synchronization of neurons within the mPFC. These findings suggest that enhancement of theta-slow gamma coupling reflects a compensatory mechanism to maintain spatial working memory performance in the setting of increased difficulty.

Floating phase in the one-dimensional transverse axial next-nearest-neighbor Ising model.

PubMed

Chandra, Anjan Kumar; Dasgupta, Subinay

2007-02-01

To study the ground state of an axial next-nearest-neighbor Ising chain under transverse field as a function of frustration parameter kappa and field strength Gamma, we present here two different perturbative analyses. In one, we consider the (known) ground state at kappa=0.5 and Gamma=0 as the unperturbed state and treat an increase of the field from 0 to Gamma coupled with an increase of kappa from 0.5 to 0.5+rGamma/J as perturbation. The first-order perturbation correction to eigenvalue can be calculated exactly and we could conclude that there are only two phase-transition lines emanating from the point kappa=0.5, Gamma=0. In the second perturbation scheme, we consider the number of domains of length 1 as the perturbation and obtain the zeroth-order eigenfunction for the perturbed ground state. From the longitudinal spin-spin correlation, we conclude that floating phase exists for small values of transverse field over the entire region intermediate between the ferromagnetic phase and antiphase.

Performance evaluation for pinhole collimators of small gamma camera by MTF and NNPS analysis: Monte Carlo simulation study

NASA Astrophysics Data System (ADS)

Jeon, Hosang; Kim, Hyunduk; Cha, Bo Kyung; Kim, Jong Yul; Cho, Gyuseong; Chung, Yong Hyun; Yun, Jong-Il

2009-06-01

Presently, the gamma camera system is widely used in various medical diagnostic, industrial and environmental fields. Hence, the quantitative and effective evaluation of its imaging performance is essential for design and quality assurance. The National Electrical Manufacturers Association (NEMA) standards for gamma camera evaluation are insufficient to perform sensitive evaluation. In this study, modulation transfer function (MTF) and normalized noise power spectrum (NNPS) will be suggested to evaluate the performance of small gamma camera with changeable pinhole collimators using Monte Carlo simulation. We simulated the system with a cylinder and a disk source, and seven different pinhole collimators from 1- to 4-mm-diameter pinhole with lead. The MTF and NNPS data were obtained from output images and were compared with full-width at half-maximum (FWHM), sensitivity and differential uniformity. In the result, we found that MTF and NNPS are effective and novel standards to evaluate imaging performance of gamma cameras instead of conventional NEMA standards.

Results from the energetic gamma-ray experiment telescope (EGRET) on the Compton Observatory

NASA Technical Reports Server (NTRS)

Fichtel, C. E.; Bertsch, D. L.; Dingus, B.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Kwok, P. W.; Lin, Y. C.; Mattox, J. R.

1993-01-01

The Energetic Gamma-Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory (CGRO) covers the high energy gamma ray energy range, approximately 30 MeV to 30 GeV, with a sensitivity considerably greater than earlier high energy gamma-ray satellites. Thus far, 4 pulsars have been detected and their properties measured, including in 3 cases the energy spectrum as a function of phase. The details of the galactic plane are being mapped and a spectra of the center region has been obtained in good agreement with that expected from cosmic ray interactions. The Magellanic clouds have been examined with the Large Magellanic Cloud (LMC) having been detected at a level consistent with it having a cosmic ray density compatible with quasi-stable equilibrium. Sixteen Active Galactic Nuclei (AGN's) have been seen thus far with a high degree of certainty including 12 quasars and 4 BL Lac objects, but no Seyferts. Time variation has been detected in some of these AGN's

Continuous in vivo infusion of interferon-gamma (IFN-gamma) enhances engraftment of syngeneic wild-type cells in Fanca-/- and Fancg-/- mice.

PubMed

Si, Yue; Ciccone, Samantha; Yang, Feng-Chun; Yuan, Jin; Zeng, Daisy; Chen, Shi; van de Vrugt, Henri J; Critser, John; Arwert, Fre; Haneline, Laura S; Clapp, D Wade

2006-12-15

Fanconi anemia (FA) is a heterogeneous genetic disorder characterized by bone marrow (BM) failure and cancer susceptibility. Identification of the cDNAs of FA complementation types allows the potential of using gene transfer technology to introduce functional cDNAs as transgenes into autologous stem cells and provide a cure for the BM failure in FA patients. However, strategies to enhance the mobilization, transduction, and engraftment of exogenous stem cells are required to optimize efficacy prior to widespread clinical use. Hypersensitivity of Fancc-/- cells to interferon-gamma (IFN-gamma), a nongenotoxic immune-regulatory cytokine, enhances engraftment of syngeneic wild-type (WT) cells in Fancc-/- mice. However, whether this phenotype is of broad relevance in other FA complementation groups is unresolved. Here we show that primitive and mature myeloid progenitors in Fanca-/- and Fancg-/- mice are hypersensitive to IFN-gamma and that in vivo infusion of IFN-gamma at clinically relevant concentrations was sufficient to allow consistent long-term engraftment of isogenic WT repopulating stem cells. Given that FANCA, FANCC, and FANCG complementation groups account for more than 90% of all FA patients, these data provide evidence that IFN-gamma conditioning may be a useful nongenotoxic strategy for myelopreparation in FA patients.

Physical, proximate, functional and pasting properties of flour produced from gamma irradiated cowpea (Vigna unguiculata, L. Walp)

NASA Astrophysics Data System (ADS)

Darfour, B.; Wilson, D. D.; Ofosu, D. O.; Ocloo, F. C. K.

2012-04-01

Cowpeas are leguminous seeds widely produced and consumed in most developing countries of sub Saharan Africa. The aim of this study was to determine the physical, proximate, functional and pasting properties of flour obtained from gamma irradiated cowpea. Four cowpea cultivars were irradiated with gamma radiation at dose levels of 0.25, 0.5, 0.75, 1.0 and 1.5 kGy with the unirradiated cultivars serving as controls. The samples were hammer milled, sieved and stored at 4 °C for analysis. Physical, proximate, functional, pasting properties were determined using appropriate methods. In general, the irradiation dose applied to cowpea for insect control did not significantly affect the physical and proximate properties of the flour. However, significant increase (p<0.05) was achieved in paste bulk density, water and oil absorption capacities, foam capacities and least gelation concentrations of flour in general, which may be attributed to the irradiation. The radiation reduced the swelling power and water solubility index significantly. The peak temperature, peak viscosity and setback viscosity of the pastes were significantly (p<0.05) reduced while breakdown viscosity was significantly (p<0.05) increased by the radiation. It was established that the doses used on cowpea affected both the functional and pasting properties of the flour.

Disruption of Prefrontal Cortex Large Scale Neuronal Activity by Different Classes of Psychotomimetic Drugs

PubMed Central

Wood, Jesse; Kim, Yunbok; Moghaddam, Bita

2012-01-01

In the absence of overt cellular pathology but profound perceptual disorganization and cognitive deficits, schizophrenia is increasingly considered a disorder of neural coordination. Thus, different causal factors can similarly interrupt the dynamic function of neuronal ensembles and networks, in particular in the prefrontal cortex (PFC), leading to behavioral disorganization. The importance of establishing preclinical biomarkers for this aberrant function has prompted investigations into the nature of psychotomimetic drug effects on PFC neuronal activity. The drugs used in this context include serotonergic hallucinogens, amphetamine, and NMDA receptor antagonists. A prominent line of thinking is that these drugs create psychotomimetic states by similarly disinhibiting the activity of PFC pyramidal neurons. In the present study we did not find evidence in support of this mechanism in PFC subregions of freely moving rats. Whereas the NMDA receptor antagonist MK801 increased PFC population activity, the serotonergic hallucinogen DOI dose-dependently decreased population activity. Amphetamine did not strongly affect this measure. Despite different effects on the direction of change in activity, all three drugs caused similar net disruptions of population activity and modulated gamma oscillations. We also observed reduced correlations between spikerate and LFP power selectively in the gamma band suggesting that these drugs disconnect spike-discharge from PFC gamma oscillators. Gamma band oscillations support cognitive functions affected in schizophrenia. These findings provide insight into mechanisms that may lead to cortical processing deficits in schizophrenia and provide a novel electrophysiological approach for phenotypic characterization of animal models of this disease. PMID:22378875

Crystal Structure of the MACPF Domain of Human Complement Protein C8[alpha] in Complex with the C8[gamma] Subunit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Slade, Daniel J.; Lovelace, Leslie L.; Chruszcz, Maksymilian

2010-03-04

Human C8 is one of five complement components (C5b, C6, C7, C8, and C9) that assemble on bacterial membranes to form a porelike structure referred to as the 'membrane attack complex' (MAC). C8 contains three genetically distinct subunits (C8{alpha}, C8{beta}, C8{gamma}) arranged as a disulfide-linked C8{alpha}-{gamma} dimer that is noncovalently associated with C8{beta}. C6, C7 C8{alpha}, C8{beta}, and C9 are homologous. All contain N- and C-terminal modules and an intervening 40-kDa segment referred to as the membrane attack complex/perforin (MACPF) domain. The C8{gamma} subunit is unrelated and belongs to the lipocalin family of proteins that display a {beta}-barrel fold andmore » generally bind small, hydrophobic ligands. Several hundred proteins with MACPF domains have been identified based on sequence similarity; however, the structure and function of most are unknown. Crystal structures of the secreted bacterial protein Plu-MACPF and the human C8{alpha} MACPF domain were recently reported and both display a fold similar to those of the bacterial pore-forming cholesterol-dependent cytolysins (CDCs). In the present study, we determined the crystal structure of the human C8{alpha} MACPF domain disulfide-linked to C8{gamma} ({alpha}MACPF-{gamma}) at 2.15 {angstrom} resolution. The {alpha}MACPF portion has the predicted CDC-like fold and shows two regions of interaction with C8{gamma}. One is in a previously characterized 19-residue insertion (indel) in C8{alpha} and fills the entrance to the putative C8{gamma} ligand-binding site. The second is a hydrophobic pocket that makes contact with residues on the side of the C8{gamma} {beta}-barrel. The latter interaction induces conformational changes in {alpha}MACPF that are likely important for C8 function. Also observed is structural conservation of the MACPF signature motif Y/W-G-T/S-H-F/Y-X{sub 6}-G-G in {alpha}MACPF and Plu-MACPF, and conservation of several key glycine residues known to be important for refolding and pore formation by CDCs.« less

Electrocorticographic high gamma activity versus electrical cortical stimulation mapping of naming.

PubMed

Sinai, Alon; Bowers, Christopher W; Crainiceanu, Ciprian M; Boatman, Dana; Gordon, Barry; Lesser, Ronald P; Lenz, Frederick A; Crone, Nathan E

2005-07-01

Subdural electrocorticographic (ECoG) recordings in patients undergoing epilepsy surgery have shown that functional activation is associated with event-related broadband gamma activity in a higher frequency range (>70 Hz) than previously studied in human scalp EEG. To investigate the utility of this high gamma activity (HGA) for mapping language cortex, we compared its neuroanatomical distribution with functional maps derived from electrical cortical stimulation (ECS), which remains the gold standard for predicting functional impairment after surgery for epilepsy, tumours or vascular malformations. Thirteen patients had undergone subdural electrode implantation for the surgical management of intractable epilepsy. Subdural ECoG signals were recorded while each patient verbally named sequentially presented line drawings of objects, and estimates of event-related HGA (80-100 Hz) were made at each recording site. Routine clinical ECS mapping used a subset of the same naming stimuli at each cortical site. If ECS disrupted mouth-related motor function, i.e. if it affected the mouth, lips or tongue, naming could not be tested with ECS at the same cortical site. Because naming during ECoG involved these muscles of articulation, the sensitivity and specificity of ECoG HGA were estimated relative to both ECS-induced impairments of naming and ECS disruption of mouth-related motor function. When these estimates were made separately for 12 electrode sites per patient (the average number with significant HGA), the specificity of ECoG HGA with respect to ECS was 78% for naming and 81% for mouth-related motor function, and equivalent sensitivities were 38% and 46%, respectively. When ECS maps of naming and mouth-related motor function were combined, the specificity and sensitivity of ECoG HGA with respect to ECS were 84% and 43%, respectively. This study indicates that event-related ECoG HGA during confrontation naming predicts ECS interference with naming and mouth-related motor function with good specificity but relatively low sensitivity. Its favourable specificity suggests that ECoG HGA can be used to construct a preliminary functional map that may help identify cortical sites of lower priority for ECS mapping. Passive recordings of ECoG gamma activity may be done simultaneously at all electrode sites without the risk of after-discharges associated with ECS mapping, which must be done sequentially at pairs of electrodes. We discuss the relative merits of these two functional mapping techniques.

Effect of gamma interferon on lung function of mustard gas exposed patients, after 15 years.

PubMed

Ghanei, Mostafa; Panahi, Yoones; Mojtahedzadeh, Mojtaba; Khalili, Ali Reza Hosseini; Aslani, Jafar

2006-01-01

Bronchiolitis has been known to be among the main the pathological features of lung lesions in Mustard Gas (MG) exposed patients. The purpose of this research was to evaluate the efficacy of interferon gamma-1b on the lung function in MG exposed patients with bronchiolitis. Thirty-six bronchiolitis patients, whose lung lesion had been diagnosed through High Resolution Computerized Tomography (HRCT) of the chest and also pathological study, were divided into two 18-member case and control groups. Both groups were receiving their conventional treatment (inhaled Felixotide and Servent). The case group were treated for 6 months with a combination of 200 microg of interferon gamma-1b (given three times per week subcutaneously) plus 7.5 mg of prednisolone (given once a day), while the control group received their previous conventional medications. Lung function was measured at base line and after 1, 3 and 6 months of treatment. In case and control groups, Forced Expiratory Volume in first second (FEV1) did not have statistical differences at the base line (49.3 +/- 2.9 and 48.7 +/- 4.1, respectively = 0.6), whereas a significant increase was seen in the case group (66.3 +/- 5.4) compared control group (57.3 +/- 8.6) at the subsequent months (P = 0.001 for the difference between the groups). Similar pattern of increase was observed in Forced Vital Capacity (FVC). The findings of this study indicate that a 6-month treatment with interferon gamma-1b plus a low-dose prednisolone is associated with an improvement in the lung function in mustard-gas exposed patients with bronchiolitis.

Exploring the relationship between cortical GABA concentrations, auditory gamma-band responses and development in ASD: Evidence for an altered maturational trajectory in ASD.

PubMed

Port, Russell G; Gaetz, William; Bloy, Luke; Wang, Dah-Jyuu; Blaskey, Lisa; Kuschner, Emily S; Levy, Susan E; Brodkin, Edward S; Roberts, Timothy P L

2017-04-01

Autism spectrum disorder (ASD) is hypothesized to arise from imbalances between excitatory and inhibitory neurotransmission (E/I imbalance). Studies have demonstrated E/I imbalance in individuals with ASD and also corresponding rodent models. One neural process thought to be reliant on E/I balance is gamma-band activity (Gamma), with support arising from observed correlations between motor, as well as visual, Gamma and underlying GABA concentrations in healthy adults. Additionally, decreased Gamma has been observed in ASD individuals and relevant animal models, though the direct relationship between Gamma and GABA concentrations in ASD remains unexplored. This study combined magnetoencephalography (MEG) and edited magnetic resonance spectroscopy (MRS) in 27 typically developing individuals (TD) and 30 individuals with ASD. Auditory cortex localized phase-locked Gamma was compared to resting Superior Temporal Gyrus relative cortical GABA concentrations for both children/adolescents and adults. Children/adolescents with ASD exhibited significantly decreased GABA+/Creatine (Cr) levels, though typical Gamma. Additionally, these children/adolescents lacked the typical maturation of GABA+/Cr concentrations and gamma-band coherence. Furthermore, children/adolescents with ASD additionally failed to exhibit the typical GABA+/Cr to gamma-band coherence association. This altered coupling during childhood/adolescence may result in Gamma decreases observed in the adults with ASD. Therefore, individuals with ASD exhibit improper local neuronal circuitry maturation during a childhood/adolescence critical period, when GABA is involved in configuring of such circuit functioning. Provocatively a novel line of treatment is suggested (with a critical time window); by increasing neural GABA levels in children/adolescents with ASD, proper local circuitry maturation may be restored resulting in typical Gamma in adulthood. Autism Res 2017, 10: 593-607. © 2016 International Society for Autism Research, Wiley Periodicals, Inc. © 2016 International Society for Autism Research, Wiley Periodicals, Inc.

Dynamic gamma knife radiosurgery

NASA Astrophysics Data System (ADS)

Luan, Shuang; Swanson, Nathan; Chen, Zhe; Ma, Lijun

2009-03-01

Gamma knife has been the treatment of choice for various brain tumors and functional disorders. Current gamma knife radiosurgery is planned in a 'ball-packing' approach and delivered in a 'step-and-shoot' manner, i.e. it aims to 'pack' the different sized spherical high-dose volumes (called 'shots') into a tumor volume. We have developed a dynamic scheme for gamma knife radiosurgery based on the concept of 'dose-painting' to take advantage of the new robotic patient positioning system on the latest Gamma Knife C™ and Perfexion™ units. In our scheme, the spherical high dose volume created by the gamma knife unit will be viewed as a 3D spherical 'paintbrush', and treatment planning reduces to finding the best route of this 'paintbrush' to 'paint' a 3D tumor volume. Under our dose-painting concept, gamma knife radiosurgery becomes dynamic, where the patient moves continuously under the robotic positioning system. We have implemented a fully automatic dynamic gamma knife radiosurgery treatment planning system, where the inverse planning problem is solved as a traveling salesman problem combined with constrained least-square optimizations. We have also carried out experimental studies of dynamic gamma knife radiosurgery and showed the following. (1) Dynamic gamma knife radiosurgery is ideally suited for fully automatic inverse planning, where high quality radiosurgery plans can be obtained in minutes of computation. (2) Dynamic radiosurgery plans are more conformal than step-and-shoot plans and can maintain a steep dose gradient (around 13% per mm) between the target tumor volume and the surrounding critical structures. (3) It is possible to prescribe multiple isodose lines with dynamic gamma knife radiosurgery, so that the treatment can cover the periphery of the target volume while escalating the dose for high tumor burden regions. (4) With dynamic gamma knife radiosurgery, one can obtain a family of plans representing a tradeoff between the delivery time and the dose distributions, thus giving the clinician one more dimension of flexibility of choosing a plan based on the clinical situations.

p53-dependent control of cell death by nicastrin: lack of requirement for presenilin-dependent gamma-secretase complex.

PubMed

Pardossi-Piquard, Raphaëlle; Dunys, Julie; Giaime, Emilie; Guillot-Sestier, Marie-Victoire; St George-Hyslop, Peter; Checler, Frédéric; Alves da Costa, Cristine

2009-04-01

Nicastrin (NCT) is a component of the presenilin (PS)-dependent gamma-secretase complexes that liberate amyloid beta-peptides from the beta-Amyloid Precursor Protein. Several lines of evidence indicate that the members of these complexes could also contribute to the control of cell death. Here we show that over-expression of NCT increases the viability of human embryonic kidney (HEK293) cells and decreases staurosporine (STS)- and thapsigargin (TPS)-induced caspase-3 activation in various cell lines from human and neuronal origins by Akt-dependent pathway. NCT lowers p53 expression, transcriptional activity and promoter transactivation and reduces p53 phosphorylation. NCT-associated protection against STS-stimulated cell death was completely abolished by p53 deficiency. Conversely, the depletion of NCT drastically enhances STS-induced caspase-3 activation and p53 pathway and favored p53 nuclear translocation. We examined whether NCT protective function depends on PS-dependent gamma-secretase activity. First, a 29-amino acid deletion known to reduce NCT-dependent amyloid beta-peptide production did not affect NCT-associated protective phenotype. Second, NCT still reduces STS-induced caspase-3 activation in fibroblasts lacking PS1 and PS2. Third, the gamma-secretase inhibitor DFK167 did not affect NCT-mediated reduction of p53 activity. Altogether, our study indicates that NCT controls cell death via phosphoinositide 3-kinase/Akt and p53-dependent pathways and that this function remains independent of the activity and molecular integrity of the gamma-secretase complexes.

Neural synchronization deficits linked to cortical hyper-excitability and auditory hypersensitivity in fragile X syndrome.

PubMed

Ethridge, Lauren E; White, Stormi P; Mosconi, Matthew W; Wang, Jun; Pedapati, Ernest V; Erickson, Craig A; Byerly, Matthew J; Sweeney, John A

2017-01-01

Studies in the fmr1 KO mouse demonstrate hyper-excitability and increased high-frequency neuronal activity in sensory cortex. These abnormalities may contribute to prominent and distressing sensory hypersensitivities in patients with fragile X syndrome (FXS). The current study investigated functional properties of auditory cortex using a sensory entrainment task in FXS. EEG recordings were obtained from 17 adolescents and adults with FXS and 17 age- and sex-matched healthy controls. Participants heard an auditory chirp stimulus generated using a 1000-Hz tone that was amplitude modulated by a sinusoid linearly increasing in frequency from 0-100 Hz over 2 s. Single trial time-frequency analyses revealed decreased gamma band phase-locking to the chirp stimulus in FXS, which was strongly coupled with broadband increases in gamma power. Abnormalities in gamma phase-locking and power were also associated with theta-gamma amplitude-amplitude coupling during the pre-stimulus period and with parent reports of heightened sensory sensitivities and social communication deficits. This represents the first demonstration of neural entrainment alterations in FXS patients and suggests that fast-spiking interneurons regulating synchronous high-frequency neural activity have reduced functionality. This reduced ability to synchronize high-frequency neural activity was related to the total power of background gamma band activity. These observations extend findings from fmr1 KO models of FXS, characterize a core pathophysiological aspect of FXS, and may provide a translational biomarker strategy for evaluating promising therapeutics.

Characterizing the source properties of terrestrial gamma ray flashes

NASA Astrophysics Data System (ADS)

Dwyer, Joseph R.; Liu, Ningyu; Eric Grove, J.; Rassoul, Hamid; Smith, David M.

2017-08-01

Monte Carlo simulations are used to determine source properties of terrestrial gamma ray flashes (TGFs) as a function of atmospheric column depth and beaming geometry. The total mass per unit area traversed by all the runaway electrons (i.e., the total grammage) during a TGF, Ξ, is introduced, defined to be the total distance traveled by all the runaway electrons along the electric field lines multiplied by the local air mass density along their paths. It is shown that key properties of TGFs may be directly calculated from Ξ and its time derivative, including the gamma ray emission rate, the current moment, and the optical power of the TGF. For the calculations presented in this paper, a standard TGF gamma ray fluence, F0 = 0.1 cm-2 above 100 keV for a spacecraft altitude of 500 km, and a standard total grammage, Ξ0 = 1018 g/cm2, are introduced, and results are presented in terms of these values. In particular, the current moments caused by the runaway electrons and their accompanying ionization are found for a standard TGF fluence, as a function of source altitude and beaming geometry, allowing a direct comparison between the gamma rays measured in low-Earth orbit and the VLF-LF radio frequency emissions recorded on the ground. Such comparisons should help test and constrain TGF models and help identify the roles of lightning leaders and streamers in the production of TGFs.

Three outer arm dynein heavy chains of Chlamydomonas reinhardtii operate in a coordinated fashion both in vitro and in vivo.

PubMed

Takazaki, Hiroko; Liu, Zhongmei; Jin, Mingyue; Kamiya, Ritsu; Yasunaga, Takuo

2010-07-01

Outer arm dynein (OAD) in cilia and flagella contains two to three nonidentical heavy chains (HCs) that possess motor activity. In Chlamydomonas, flagellar OAD contains three HCs, alpha-, beta-, and gamma-HCs, each appearing to have a distinct role. To determine the precise molecular mechanism of their function, cross-sectional electron micrographs of wild-type and single HC-disruption mutants were compared and statistically analyzed. While the alpha-HC mutant displayed an OAD of lower density, which was attributed to a lack of alpha-HC, the OAD of beta- and gamma-HC mutants not only lacked the corresponding HC, but was also significantly affected in its structure, particularly with respect to the localization of alpha-HC. The lack of beta-HC induced mislocalization of alpha-HC, while a disruption of the gamma-HC gene resulted in the synchronized movement of alpha-HC and beta-HC in the manners for stacking. Interestingly, using cryo-electron microscopy, purified OADs were typically observed consisting of two stacked heads and an independent single head, which presumably corresponded to gamma-HC. This conformation is different from previous reports in which the three HCs displayed a stacked form in flagella observed by cryo-electron tomography and a bouquet structure on mica in deep-etch replica images. These results suggest that gamma-HC supports the tight stacking arrangement of inter or intra alpha-/beta-HC to facilitate the proper functioning of OAD. 2010 Wiley-Liss, Inc.

Implementation of Microcalorimeter Array Technology for Safeguards of Nuclear Material

NASA Astrophysics Data System (ADS)

Kossmann, Shannon; Mateju, Klara; Koehler, Katrina; Croce, Mark

2018-03-01

Safeguards of nuclear materials depend on both destructive and nondestructive assay (DA and NDA, respectively). Ultra-high-resolution microcalorimeter gamma spectroscopy has the potential to substantially reduce the performance gap between NDA and DA methods in determination of plutonium isotopic composition. This paper details the setup of a cryostat and microwave readout system for microcalorimeter gamma spectroscopy, the functionality of which has been successfully demonstrated.

Factors affecting the appearance of the hump charge movement component in frog cut twitch fibers.

PubMed

Hui, C S

1991-08-01

Charge movement was measured in frog cut twitch fibers with the double Vaseline gap technique. Five manipulations listed below were applied to investigate their effects on the hump component (I gamma) in the ON segments of TEST minus CONTROL current traces. When external Cl-1 was replaced by MeSO3- to eliminate Cl current, I gamma peaked earlier due to a few millivolts shift of the voltage dependence of I gamma kinetics in the negative direction. The Q-V plots in the TEA.Cl and TEA.MeSO3 solutions were well fitted by a sum of two Boltzmann distribution functions. The more steeply voltage-dependent component (Q gamma) had a V approximately 6 mV more negative in the TEA.MeSO3 solution than in the TEA.Cl solution. These voltage shifts were partially reversible. When creatine phosphate in the end pool solution was removed, the I gamma hump disappeared slowly over the course of 20-30 min, partly due to a suppression of Q gamma. The hump reappeared when creatine phosphate was restored. When 0.2-1.0 mM Cd2+ was added to the center pool solution to block inward Ca current, the I gamma hump became less prominent due to a prolongation in the time course of I gamma but not to a suppression of Q gamma. When the holding potential was changed from -90 to -120 mV, the amplitude of I beta was increased, thereby obscuring the I gamma hump. Finally, when a cut fiber was stimulated repetitively, I gamma lost its hump appearance because its time course was prolonged. In an extreme case, a 5-min resting interval was insufficient for a complete recovery of the waveform. In general, a stimulation rate of once per minute had a negligible effect on the shape of I gamma. Of the five manipulations, MeSO3- has the least perturbation on the appearance of I gamma and is potentially a better substitute for Cl- than SO2-(4) in eliminating Cl current if the appearance of the I gamma hump is to be preserved.

Reduced gamma frequency in the medial frontal cortex of aged rats during behavior and rest: implications for age-related behavioral slowing

PubMed Central

Insel, Nathan; Patron, Lilian A.; Hoang, Lan T.; Nematollahi, Saman; Schimanski, Lesley A.; Lipa, Peter; Barnes, Carol A.

2012-01-01

Age-related cognitive and behavioral slowing may be caused by changes in the speed of neural signaling or by changes in the number of signaling steps necessary to achieve a given function. In the mammalian cortex, neural communication is organized by a 30–100 Hz “gamma” oscillation. There is a putative link between the gamma frequency and the speed of processing in a neural network: the dynamics of pyramidal neuron membrane time constants suggest that synaptic integration is framed by the gamma cycle, and pharmacological slowing of gamma also slows reaction times on behavioral tasks. The present experiments identify reductions in a robust 40–70 Hz gamma oscillation in the aged rat medial frontal cortex. The reductions were observed in the form of local field potentials (LFPs), later peaks in fast-spiking neuron autocorrelations, and delays in the spiking of inhibitory neurons following local excitatory signals. Gamma frequency did not vary with movement speed, but rats with slower gamma also moved more slowly. Gamma frequency age differences were not observed in hippocampus. Hippocampal CA1 fast-spiking neurons exhibited inter-spike intervals consistent with a fast (70–100 Hz) gamma frequency, a pattern maintained across theta phases and theta frequencies independent of fluctuations in the neurons’ average firing rates. We propose that an average lengthening of the cortical 15–25 ms gamma cycle is one factor contributing to age-related slowing, and that future attempts to offset cognitive declines will find a target in the response of fast-spiking inhibitory neurons to excitatory inputs. PMID:23152616

(n,{gamma}) Experiments on tin isotopes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baramsai, B.; Mitchell, G. E.; Walker, C. L.

2013-04-19

Neutron capture experiments on highly enriched {sup 117,119}Sn isotopes were performed with the DANCE detector array located at the Los Alamos Neutron Science Center. The DANCE detector provides detailed information about the multi-step {gamma}-ray cascade following neutron capture. Analysis of the experimental data provides important information to improve understanding of the neutron capture reaction, including a test of the statistical model, the assignment of spins and parities of neutron resonances, and information concerning the Photon Strength Function (PSF) and Level Density (LD) below the neutron separation energy. Preliminary results for the (n,{gamma}) reaction on {sup 117,119}Sn are presented. Resonance spinsmore » of the odd-A tin isotopes were almost completely unknown. Resonance spins and parities have been assigned via analysis of the multi-step {gamma}-ray spectra and directional correlations.« less

Neutron and gamma-ray energy reconstruction for characterization of special nuclear material

DOE PAGES

Clarke, Shaun D.; Hamel, Michael C.; Di fulvio, Angela; ...

2017-06-30

Characterization of special nuclear material may be performed using energy spectroscopy of either the neutron or gamma-ray emissions from the sample. Gamma-ray spectroscopy can be performed relatively easily using high-resolution semiconductors such as high-purity germanium. Neutron spectroscopy, by contrast, is a complex inverse problem. Here, results are presented for 252Cf and PuBe energy spectra unfolded using a single EJ309 organic scintillator; excellent agreement is observed with the reference spectra. Neutron energy spectroscopy is also possible using a two-plane detector array, whereby time-offlight kinematics can be used. With this system, energy spectra can also be obtained as a function of position.more » Finally, spatial-dependent energy spectra are presented for neutron and gamma-ray sources that are in excellent agreement with expectations.« less

Gamma thermometer based reactor core liquid level detector

DOEpatents

Burns, Thomas J.

1983-01-01

A system is provided which employs a modified gamma thermometer for determining the liquid coolant level within a nuclear reactor core. The gamma thermometer which normally is employed to monitor local core heat generation rate (reactor power), is modified by thermocouple junctions and leads to obtain an unambiguous indication of the presence or absence of coolant liquid at the gamma thermometer location. A signal processor generates a signal based on the thermometer surface heat transfer coefficient by comparing the signals from the thermocouples at the thermometer location. The generated signal is a direct indication of loss of coolant due to the change in surface heat transfer when coolant liquid drops below the thermometer location. The loss of coolant indication is independent of reactor power at the thermometer location. Further, the same thermometer may still be used for the normal power monitoring function.

Neutron and gamma-ray energy reconstruction for characterization of special nuclear material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clarke, Shaun D.; Hamel, Michael C.; Di fulvio, Angela

Characterization of special nuclear material may be performed using energy spectroscopy of either the neutron or gamma-ray emissions from the sample. Gamma-ray spectroscopy can be performed relatively easily using high-resolution semiconductors such as high-purity germanium. Neutron spectroscopy, by contrast, is a complex inverse problem. Here, results are presented for 252Cf and PuBe energy spectra unfolded using a single EJ309 organic scintillator; excellent agreement is observed with the reference spectra. Neutron energy spectroscopy is also possible using a two-plane detector array, whereby time-offlight kinematics can be used. With this system, energy spectra can also be obtained as a function of position.more » Finally, spatial-dependent energy spectra are presented for neutron and gamma-ray sources that are in excellent agreement with expectations.« less

Effect of gamma irradiation on ethylene propylene diene terpolymer rubber composites

NASA Astrophysics Data System (ADS)

Abou Zeid, M. M.; Rabie, S. T.; Nada, A. A.; Khalil, A. M.; Hilal, R. H.

2008-01-01

Composites of ethylene propylene dine terpolymer rubber (EPDM), high density polyethylene (HDPE) and ground tire rubber powder (GTR) at different ratios were subjected to gamma irradiation at various doses up to 250 kGy. The physical, mechanical and thermal properties were investigated as a function of irradiation dose and blend composition. Gamma irradiation led to a significant improvement in the properties for all blend compositions. The results indicate that the improvement in properties is inversely proportional to the substituted ratio of GTR, attributed to the development of an interfacial adhesion between GTR and blend components. The results were confirmed by examining the fracture surfaces by scanning electron microscopy.

Generating Correlated Gamma Sequences for Sea-Clutter Simulation

DTIC Science & Technology

2012-03-01

generation of correlated Gamma random fields via SIRP theory is examined in [Conte et al. 1991, Armstrong & Griffiths 1991]. In these papers , the Gamma...2 〉2 + |〈x[n]x∗[n+ k]〉|2 . (4) Because 〈 |x|2 〉2 = z̄2 and |〈x[n]x∗[n+ k]〉|2 ≥ 0, this results in 〈z[n]z[n+ k]〉 ≥ z̄2 if the real- isation of z[n] is...linear map- ping. In a practical situation, a process with a given auto-covariance function would be specified. It is shown that by using an

Real-Time Airborne Gamma-Ray Background Estimation Using NASVD with MLE and Radiation Transport for Calibration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kulisek, Jonathan A.; Schweppe, John E.; Stave, Sean C.

2015-06-01

Helicopter-mounted gamma-ray detectors can provide law enforcement officials the means to quickly and accurately detect, identify, and locate radiological threats over a wide geographical area. The ability to accurately distinguish radiological threat-generated gamma-ray signatures from background gamma radiation in real time is essential in order to realize this potential. This problem is non-trivial, especially in urban environments for which the background may change very rapidly during flight. This exacerbates the challenge of estimating background due to the poor counting statistics inherent in real-time airborne gamma-ray spectroscopy measurements. To address this, we have developed a new technique for real-time estimation ofmore » background gamma radiation from aerial measurements. This method is built upon on the noise-adjusted singular value decomposition (NASVD) technique that was previously developed for estimating the potassium (K), uranium (U), and thorium (T) concentrations in soil post-flight. The method can be calibrated using K, U, and T spectra determined from radiation transport simulations along with basis functions, which may be determined empirically by applying maximum likelihood estimation (MLE) to previously measured airborne gamma-ray spectra. The method was applied to both measured and simulated airborne gamma-ray spectra, with and without man-made radiological source injections. Compared to schemes based on simple averaging, this technique was less sensitive to background contamination from the injected man-made sources and may be particularly useful when the gamma-ray background frequently changes during the course of the flight.« less

High-gamma activity in the human hippocampus and parahippocampus during inter-trial rest periods of a virtual navigation task.

PubMed

Pu, Yi; Cornwell, Brian R; Cheyne, Douglas; Johnson, Blake W

2018-05-19

In rodents, hippocampal cell assemblies formed during learning of a navigation task are observed to re-emerge during resting (offline) periods, accompanied by high-frequency oscillations (HFOs). This phenomenon is believed to reflect mechanisms for strengthening newly-formed memory traces. Using magnetoencephalography recordings and a beamforming source location algorithm (synthetic aperture magnetometry), we investigated high-gamma (80-140 Hz) oscillations in the hippocampal region in 18 human participants during inter-trial rest periods in a virtual navigation task. We found right hippocampal gamma oscillations mirrored the pattern of theta power in the same region during navigation, varying as a function of environmental novelty. Gamma power during inter-trial rest periods was positively correlated with theta power during navigation in the first task set when the environment was new and predicted greater performance improvement in the subsequent task set two where the environment became familiar. These findings provide evidence for human hippocampal reactivation accompanied by high-gamma activities immediately after learning and establish a link between hippocampal high-gamma activities and subsequent memory performance. Copyright © 2018 Elsevier Inc. All rights reserved.

Support vector machines for prediction and analysis of beta and gamma-turns in proteins.

PubMed

Pham, Tho Hoan; Satou, Kenji; Ho, Tu Bao

2005-04-01

Tight turns have long been recognized as one of the three important features of proteins, together with alpha-helix and beta-sheet. Tight turns play an important role in globular proteins from both the structural and functional points of view. More than 90% tight turns are beta-turns and most of the rest are gamma-turns. Analysis and prediction of beta-turns and gamma-turns is very useful for design of new molecules such as drugs, pesticides, and antigens. In this paper we investigated two aspects of applying support vector machine (SVM), a promising machine learning method for bioinformatics, to prediction and analysis of beta-turns and gamma-turns. First, we developed two SVM-based methods, called BTSVM and GTSVM, which predict beta-turns and gamma-turns in a protein from its sequence. When compared with other methods, BTSVM has a superior performance and GTSVM is competitive. Second, we used SVMs with a linear kernel to estimate the support of amino acids for the formation of beta-turns and gamma-turns depending on their position in a protein. Our analysis results are more comprehensive and easier to use than the previous results in designing turns in proteins.

Stellar Photon Archaeology with Gamma-Rays

NASA Technical Reports Server (NTRS)

Stecker, Floyd W.

2009-01-01

Ongoing deep surveys of galaxy luminosity distribution functions, spectral energy distributions and backwards evolution models of star formation rates can be used to calculate the past history of intergalactic photon densities and, from them, the present and past optical depth of the Universe to gamma-rays from pair production interactions with these photons. The energy-redshift dependence of the optical depth of the Universe to gamma-rays has become known as the Fazio-Stecker relation (Fazio & Stecker 1970). Stecker, Malkan & Scully have calculated the densities of intergalactic background light (IBL) photons of energies from 0.03 eV to the Lyman limit at 13.6 eV and for 0$ < z < $6, using deep survey galaxy observations from Spitzer, Hubble and GALEX and have consequently predicted spectral absorption features for extragalactic gamma-ray sources. This procedure can also be reversed. Determining the cutoff energies of gamma-ray sources with known redshifts using the recently launched Fermi gamma-ray space telescope may enable a more precise determination of the IBL photon densities in the past, i.e., the "archaeo-IBL.", and therefore allow a better measure of the past history of the total star formation rate, including that from galaxies too faint to be observed.

Gamma band activity associated with BCI performance: simultaneous MEG/EEG study.

PubMed

Ahn, Minkyu; Ahn, Sangtae; Hong, Jun H; Cho, Hohyun; Kim, Kiwoong; Kim, Bong S; Chang, Jin W; Jun, Sung C

2013-01-01

While brain computer interface (BCI) can be employed with patients and healthy subjects, there are problems that must be resolved before BCI can be useful to the public. In the most popular motor imagery (MI) BCI system, a significant number of target users (called "BCI-Illiterates") cannot modulate their neuronal signals sufficiently to use the BCI system. This causes performance variability among subjects and even among sessions within a subject. The mechanism of such BCI-Illiteracy and possible solutions still remain to be determined. Gamma oscillation is known to be involved in various fundamental brain functions, and may play a role in MI. In this study, we investigated the association of gamma activity with MI performance among subjects. Ten simultaneous MEG/EEG experiments were conducted; MI performance for each was estimated by EEG data, and the gamma activity associated with BCI performance was investigated with MEG data. Our results showed that gamma activity had a high positive correlation with MI performance in the prefrontal area. This trend was also found across sessions within one subject. In conclusion, gamma rhythms generated in the prefrontal area appear to play a critical role in BCI performance.

[Interferon. An overview of the state of basic research with special regard to interferon-gamma].

PubMed

Günther, G; Otto, B

1993-02-01

Interferons / An overview on the state of basic research with special regard to interferon-gamma Interferons are multifunctional glycoproteins with a broad range of antiviral, antiproliferative and immunoregulatory effects on the target cell. This review deals with the basics as well as with more recent developments in interferon research. A historic overview of 35 years of interferon research since the discovery of interferons by Isaacs and Lindenmann in 1957 introduces the most important milestones in this field and appreciates the work of the participating researchers. A brief description of the classification of interferons based on different tissue sources, different antigenic properties and different induction behaviour is made. The main part of this review focuses on human interferon-gamma. We discuss recent work on the structure-function relationship of interferon-gamma. The interferon-gamma receptor and its role in signal transduction is another part of this paper. The structure and length of the C-terminal region of interferon-gamma seems to be important for receptor binding and expression of biological activities. A conservative estimate is that the family of IFN-activated genes numbers 15-20 in most cells.

Role of NADP+-dependent isocitrate dehydrogenase (NADP+-ICDH) on cellular defence against oxidative injury by gamma-rays.

PubMed

Lee, S H; Jo, S H; Lee, S M; Koh, H J; Song, H; Park, J W; Lee, W H; Huh, T L

2004-09-01

To investigate the regulation of NADPH-producing isocitrate dehydrogenase (ICDH) in cytosol (IDPc) and mitochondria (IDPm) upon gamma-ray irradiation, and the roles of IDPc and IDPm in the protection against cellular damage induced by gamma-ray irradiation. Changes of IDPc and IDPm proteins upon gamma-ray irradiation to NIH3T3 cells were analysed by immunoblotting. To increase or decrease the expression of IDPc or IDPm, NIH3T3 cells were stably transfected with mouse IDPc or IDPm cDNA in either the sense or the antisense direction. The transfected cells with either increased or decreased IDPc or IDPm were exposed to gamma-rays, and the levels of reactive oxygen species generation, protein oxidation and lipid peroxidation were measured. Both IDPc and IDPm activities were induced by gamma-ray in NIH3T3 cells. Cells with decreased expression of IDPc or IDPm had elevated reactive oxygen species generation, lipid peroxidation and protein oxidation. Conversely, overproduction of IDPc or IDPm protein partially protected the cells from oxidative damage induced by gamma-ray irradiation. The protective role of IDPc and IDPm against gamma-ray-induced cellular damage can be attributed to elevated NADPH, reducing equivalents needed for recycling reduced glutathione in the cytosol and mitochondria. Thus, a primary biological function of the ICDHs may be production of NADPH, which is a prerequisite for some cellular defence systems against oxidative damage.

Expression of alpha-AR subtypes in T lymphocytes and role of the alpha-ARs in mediating modulation of T cell function.

PubMed

Bao, Jing-Yin; Huang, Yan; Wang, Feng; Peng, Yu-Ping; Qiu, Yi-Hua

2007-01-01

Previous work in our laboratory has shown that alpha-adrenoreceptors (alpha-ARs) and beta-ARs exist on lymphocytes from functional profile, and that the receptors mediate the regulation of lymphocyte function by catecholamines. In the present study, we directly examined the expression of alpha-AR subtypes, alpha(1)-AR and alpha(2)-AR mRNAs, in T lymphocytes and explored the roles of the alpha-AR subtypes and intracellular signal transduction mechanisms linked to the receptors in mediating the modulation of T lymphocyte function. T lymphocytes from mesenteric lymph nodes of rats were purified by using a nylon wool column. Reverse transcription polymerase chain reaction was used to detect the expression of alpha(1)-AR and alpha(2)-AR mRNAs in the freshly isolated T cells and the mitogen concanavalin A (Con A)-activated lymphocytes. Colorimetric methylthiazoletetrazolium assay was employed to measure lymphocyte proliferation induced by Con A. Interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) levels in the Con A-stimulated lymphocyte culture supernatants were examined by enzyme-linked immunosorbent assay. T cells expressed both alpha(1)-AR and alpha(2)-AR mRNAs. The expression of both alpha(1)-AR and alpha(2)-AR mRNAs was significantly higher in the Con A-activated lymphocytes than in the resting lymphocytes. Phenylephrine, a selective alpha(1)-AR agonist, had no evident effect on lymphocyte proliferation nor on IFN-gamma and IL-4 production induced by Con A. However, the selective alpha(2)-AR agonist clonidine attenuated Con A-induced lymphocyte proliferation as well as IFN-gamma and IL-4 production. The inhibited lymphocyte proliferation and IFN-gamma and IL-4 production by clonidine were blocked by yohimbine, an alpha(2)-AR antagonist. Either phospholipase C inhibitor U-73122 or protein kinase C inhibitor chelerythrine partially prevented the suppressive effect of clonidine on Con A-stimulated lymphocyte proliferation and IL-4 production. T lymphocytes express both alpha(1)-ARs and alpha(2)-ARs, but only the alpha(2)-ARs participate in the suppressive modulation of lymphocyte proliferation and cytokine production in vitro. The inhibitory effect of alpha(2)-AR stimulation on lymphocyte function is partially mediated via the phospholipase C-protein kinase C pathway. (c) 2008 S. Karger AG, Basel.

Peculiar velocity effect on galaxy correlation functions in nonlinear clustering regime

NASA Astrophysics Data System (ADS)

Matsubara, Takahiko

1994-03-01

We studied the distortion of the apparent distribution of galaxies in redshift space contaminated by the peculiar velocity effect. Specifically we obtained the expressions for N-point correlation functions in redshift space with given functional form for velocity distribution f(v) and evaluated two- and three-point correlation functions quantitatively. The effect of velocity correlations is also discussed. When the two-point correlation function in real space has a power-law form, Xir(r) is proportional to r(-gamma), the redshift-space counterpart on small scales also has a power-law form but with an increased power-law index: Xis(s) is proportional to s(1-gamma). When the three-point correlation function has the hierarchical form and the two-point correlation function has the power-law form in real space, the hierarchical form of the three-point correlation function is almost preserved in redshift space. The above analytic results are compared with the direct analysis based on N-body simulation data for cold dark matter models. Implications on the hierarchical clustering ansatz are discussed in detail.

Conditional forebrain inactivation of nicastrin causes progressive memory impairment and age-related neurodegeneration.

PubMed

Tabuchi, Katsuhiko; Chen, Guiquan; Südhof, Thomas C; Shen, Jie

2009-06-03

Loss of presenilin function in adult mouse brains causes memory loss and age-related neurodegeneration. Since presenilin possesses gamma-secretase-dependent and -independent activities, it remains unknown which activity is required for presenilin-dependent memory formation and neuronal survival. To address this question, we generated postnatal forebrain-specific nicastrin conditional knock-out (cKO) mice, in which nicastrin, a subunit of gamma-secretase, is inactivated selectively in mature excitatory neurons of the cerebral cortex. nicastrin cKO mice display progressive impairment in learning and memory and exhibit age-dependent cortical neuronal loss, accompanied by astrocytosis, microgliosis, and hyperphosphorylation of the microtubule-associated protein Tau. The neurodegeneration observed in nicastrin cKO mice likely occurs via apoptosis, as evidenced by increased numbers of apoptotic neurons. These findings demonstrate an essential role of nicastrin in the execution of learning and memory and the maintenance of neuronal survival in the brain and suggest that presenilin functions in memory and neuronal survival via its role as a gamma-secretase subunit.

Log-Gamma Polymer Free Energy Fluctuations via a Fredholm Determinant Identity

NASA Astrophysics Data System (ADS)

Borodin, Alexei; Corwin, Ivan; Remenik, Daniel

2013-11-01

We prove that under n 1/3 scaling, the limiting distribution as n → ∞ of the free energy of Seppäläinen’s log-Gamma discrete directed polymer is GUE Tracy-Widom. The main technical innovation we provide is a general identity between a class of n-fold contour integrals and a class of Fredholm determinants. Applying this identity to the integral formula proved in Corwin et al. (Tropical combinatorics and Whittaker functions. http://arxiv.org/abs/1110.3489v3 [math.PR], 2012) for the Laplace transform of the log-Gamma polymer partition function, we arrive at a Fredholm determinant which lends itself to asymptotic analysis (and thus yields the free energy limit theorem). The Fredholm determinant was anticipated in Borodin and Corwin (Macdonald processes. http://arxiv.org/abs/1111.4408v3 [math.PR], 2012) via the formalism of Macdonald processes yet its rigorous proof was so far lacking because of the nontriviality of certain decay estimates required by that approach.

Evolution of the Blue and Far-Infrared Galaxy Luminosity Functions

NASA Technical Reports Server (NTRS)

Lonsdale, Carol J.; Chokshi, Arati

1993-01-01

The space density of blue-selected galaxies at moderate redshifts is determined here directly by deriving the luminosity function. Evidence is found for density evolution for moderate luminosity galaxies at a rate of (1+z) exp delta, with a best fit of delta + 4 +/- 2, between the current epoch and Z greater than about 0.1. At M(b) less than -22 evidence is found for about 0.5-1.5 mag of luminosity evolution in addition to the density evolution, corresponding to an evolutionary rate of about (1+z) exp gamma, with gamma = 0.5-2.5, but a redshift of about 0.4. Assuming a steeper faint end slope of alpha = -1.3 similar to that observed in the Virgo cluster, could explain the data with a luminosity evolution rate of gamma = 1-2, without need for any density evolution. Acceptable fits are found by comparing composite density and luminosity evolution models to faint IRAS 60 micron source counts, implying that the blue and far-IR evolutionary rates may be similar.

Dual-modality imaging with a ultrasound-gamma device for oncology

NASA Astrophysics Data System (ADS)

Polito, C.; Pellegrini, R.; Cinti, M. N.; De Vincentis, G.; Lo Meo, S.; Fabbri, A.; Bennati, P.; Cencelli, V. Orsolini; Pani, R.

2018-06-01

Recently, dual-modality systems have been developed, aimed to correlate anatomical and functional information, improving disease localization and helping oncological or surgical treatments. Moreover, due to the growing interest in handheld detectors for preclinical trials or small animal imaging, in this work a new dual modality integrated device, based on a Ultrasounds probe and a small Field of View Single Photon Emission gamma camera, is proposed.

Analysis of expressed sequence tags from a single wheat cultivar facilitates interpretation of tandem mass spectrometry data and discrimination of gamma gliadin proteins that may play different functional roles in flour

USDA-ARS?s Scientific Manuscript database

The complement of gamma gliadin genes expressed in the wheat cultivar Butte 86 was evaluated by analyzing publicly available expressed sequence tag (EST) data. Eleven contigs were assembled from 153 Butte 86 ESTs. Nine of the contigs encoded full-length proteins and four of the proteins contained an...

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mughabghab, S.

The s- and p-wave neutron strength functions and average radiative widths of fission product nuclides are reviewed. The direct capture mechanism of Land and Lynn is quantitatively varified for the two reactions /sup 42/Ca(n,..gamma..) /sup 43/Ca and /sup 136/Xe(n,..gamma..) /sup 137/Xe. Thermal capture cross sections of /sup 132/Te and /sup 126/Sn are estimated with the aid of the Lane-Lynn theory. 7 figures, 1 table.

Correlation analysis of 1 to 30 MeV celestial gamma rays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Long, J.L.

1984-01-01

This paper outlines the development of a method of producing celestial sky maps from the data generated by the University of California, Riverside's double Compton scatter gamma ray telescope. The method makes use of a correlation between the telescope's data and theoretical calculated response functions. The results of applying this technique to northern hemisphere data obtained from a 1978 balloon flight from Palestine, Texas are included.

cAMP and forskolin decrease. gamma. -aminobutyric acid-gated chloride flux in rat brain synaptoneurosomes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heuschneider, G.; Schwartz, R.D.

1989-04-01

The effects of the cyclic nucleotide cAMP on {gamma}-aminobutyric acid-gated chloride channel function were investigated. The membrane-permeant cAMP analog N{sup 6}, O{sup 2{prime}}-dibutyryladenosine 3{prime},5{prime}-cyclic monophosphate inhibited muscimol-induced {sup 36}Cl{sup {minus}} uptake into rat cerebral cortical synaptoneurosomes in a concentration-dependent manner. The inhibition was due to a decrease in the maximal effect of muscimol, with no change in potency. Similar effects were observed with 8-(4-chlorophenylthio)adenosine 3{prime},5{prime}-cyclic monophosphate, 8-bromoadenosine 3{prime},5{prime}-cyclic monophosphate, and the phosphodiesterase inhibitor isobutylmethylxanthine. The effect of endogenous cAMP accumulation on the {gamma}-aminobutyric acid-gated Cl{sup {minus}} channel was studied with forskolin, an activator of adenylate cyclase. Under identical conditions, inmore » the intact synaptoneurosomes, forskolin inhibited muscimol-induced {sup 36}Cl{sup {minus}} uptake and generated cAMP with similar potencies. Surprisingly, 1,9-dideoxyforskolin, which does not activate adenylate cyclase, also inhibited the muscimol response, suggesting that forskolin and its lipophilic derivatives may interact with the Cl{sup {minus}} channel directly. The data suggest that {gamma}-aminobutyric acid (GABA{sub A}) receptor function in brain can be regulated by cAMP-dependent phosphorylation.« less

Characterization of lipid metabolism in insulin-sensitive adipocytes differentiated from immortalized human mesenchymal stem cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prawitt, Janne; Niemeier, Andreas; Kassem, Moustapha

2008-02-15

There is a great demand for cell models to study human adipocyte function. Here we describe the adipogenic differentiation of a telomerase-immortalized human mesenchymal stem cell line (hMSC-Tert) that maintains numerous features of terminally differentiated adipocytes even after prolonged withdrawal of the peroxisome proliferator activated receptor {gamma} (PPAR{gamma}) agonist rosiglitazone. Differentiated hMSC-Tert developed the characteristic monolocular phenotype of mature adipocytes. The expression of adipocyte specific markers was highly increased during differentiation. Most importantly, the presence of the PPAR{gamma} agonist rosiglitazone was not required for the stable expression of lipoprotein lipase, adipocyte fatty acid binding protein and perilipin on mRNA andmore » protein levels. Adiponectin expression was post-transcriptionally down-regulated in the absence of rosiglitazone. Insulin sensitivity as measured by insulin-induced phosphorylation of Akt and S6 ribosomal protein was also independent of rosiglitazone. In addition to commonly used adipogenic markers, we investigated further PPAR{gamma}-stimulated proteins with a role in lipid metabolism. We observed an increase of lipoprotein receptor (VLDLR, LRP1) and apolipoprotein E expression during differentiation. Despite this increased expression, the receptor-mediated endocytosis of lipoproteins was decreased in differentiated adipocytes, suggesting that these proteins may have an additional function in adipose tissue beyond lipoprotein uptake.« less

Gamma and Beta Oscillations Define a Sequence of Neurocognitive Modes Present in Odor Processing

PubMed Central

Frederick, Donald E.; Brown, Austin; Brim, Elizabeth; Mehta, Nisarg; Vujovic, Mark

2016-01-01

Olfactory system beta (15–35 Hz) and gamma (40–110 Hz) oscillations of the local field potential in mammals have both been linked to odor learning and discrimination. Gamma oscillations represent the activity of a local network within the olfactory bulb, and beta oscillations represent engagement of a systemwide network. Here, we test whether beta and gamma oscillations represent different cognitive modes using the different demands of go/no-go and two-alternative choice tasks that previously were suggested to favor beta or gamma oscillations, respectively. We reconcile previous studies and show that both beta and gamma oscillations occur in both tasks, with gamma dominating the early odor sampling period (2–4 sniffs) and beta dominating later. The relative power and coherence of both oscillations depend separately on multiple factors within both tasks without categorical differences across tasks. While the early/gamma-associated period occurs in all trials, rats can perform above chance without the later/beta-associated period. Longer sampling, which includes beta oscillations, is associated with better performance. Gamma followed by beta oscillations therefore represents a sequence of cognitive and neural states during odor discrimination, which can be separately modified depending on the demands of a task and odor discrimination. Additionally, fast (85 Hz) and slow (70 Hz) olfactory bulb gamma oscillation sub-bands have been hypothesized to represent tufted and mitral cell networks, respectively (Manabe and Mori, 2013). We find that fast gamma favors the early and slow gamma the later (beta-dominated) odor-sampling period and that the relative contributions of these oscillations are consistent across tasks. SIGNIFICANCE STATEMENT Olfactory system gamma (40–110 Hz) and beta (15–35 Hz) oscillations of the local field potential indicate different neural firing statistics and functional circuits. We show that gamma and beta oscillations occur in stereotyped sequence during odor sampling in associative tasks, with local gamma dominating the first 250 ms of odor sniffing, followed by systemwide beta as behavioral responses are prepared. Oscillations and coupling strength between brain regions are modulated by task, odor, and learning, showing that task features can dramatically adjust the dynamics of a cortical sensory system, which changes state every ∼250 ms. Understanding cortical circuits, even at the biophysical level, depends on careful use of multiple behavioral contexts and stimuli. PMID:27445151

Gamma and Beta Oscillations Define a Sequence of Neurocognitive Modes Present in Odor Processing.

PubMed

Frederick, Donald E; Brown, Austin; Brim, Elizabeth; Mehta, Nisarg; Vujovic, Mark; Kay, Leslie M

2016-07-20

Olfactory system beta (15-35 Hz) and gamma (40-110 Hz) oscillations of the local field potential in mammals have both been linked to odor learning and discrimination. Gamma oscillations represent the activity of a local network within the olfactory bulb, and beta oscillations represent engagement of a systemwide network. Here, we test whether beta and gamma oscillations represent different cognitive modes using the different demands of go/no-go and two-alternative choice tasks that previously were suggested to favor beta or gamma oscillations, respectively. We reconcile previous studies and show that both beta and gamma oscillations occur in both tasks, with gamma dominating the early odor sampling period (2-4 sniffs) and beta dominating later. The relative power and coherence of both oscillations depend separately on multiple factors within both tasks without categorical differences across tasks. While the early/gamma-associated period occurs in all trials, rats can perform above chance without the later/beta-associated period. Longer sampling, which includes beta oscillations, is associated with better performance. Gamma followed by beta oscillations therefore represents a sequence of cognitive and neural states during odor discrimination, which can be separately modified depending on the demands of a task and odor discrimination. Additionally, fast (85 Hz) and slow (70 Hz) olfactory bulb gamma oscillation sub-bands have been hypothesized to represent tufted and mitral cell networks, respectively (Manabe and Mori, 2013). We find that fast gamma favors the early and slow gamma the later (beta-dominated) odor-sampling period and that the relative contributions of these oscillations are consistent across tasks. Olfactory system gamma (40-110 Hz) and beta (15-35 Hz) oscillations of the local field potential indicate different neural firing statistics and functional circuits. We show that gamma and beta oscillations occur in stereotyped sequence during odor sampling in associative tasks, with local gamma dominating the first 250 ms of odor sniffing, followed by systemwide beta as behavioral responses are prepared. Oscillations and coupling strength between brain regions are modulated by task, odor, and learning, showing that task features can dramatically adjust the dynamics of a cortical sensory system, which changes state every ∼250 ms. Understanding cortical circuits, even at the biophysical level, depends on careful use of multiple behavioral contexts and stimuli. Copyright © 2016 the authors 0270-6474/16/367750-18$15.00/0.

Unraveling Fungal Radiation Resistance Regulatory Networks through the Genome-Wide Transcriptome and Genetic Analyses of Cryptococcus neoformans.

PubMed

Jung, Kwang-Woo; Yang, Dong-Hoon; Kim, Min-Kyu; Seo, Ho Seong; Lim, Sangyong; Bahn, Yong-Sun

2016-11-29

The basidiomycetous fungus Cryptococcus neoformans has been known to be highly radiation resistant and has been found in fatal radioactive environments such as the damaged nuclear reactor at Chernobyl. To elucidate the mechanisms underlying the radiation resistance phenotype of C. neoformans, we identified genes affected by gamma radiation through genome-wide transcriptome analysis and characterized their functions. We found that genes involved in DNA damage repair systems were upregulated in response to gamma radiation. Particularly, deletion of recombinase RAD51 and two DNA-dependent ATPase genes, RAD54 and RDH54, increased cellular susceptibility to both gamma radiation and DNA-damaging agents. A variety of oxidative stress response genes were also upregulated. Among them, sulfiredoxin contributed to gamma radiation resistance in a peroxiredoxin/thioredoxin-independent manner. Furthermore, we found that genes involved in molecular chaperone expression, ubiquitination systems, and autophagy were induced, whereas genes involved in the biosynthesis of proteins and fatty acids/sterols were downregulated. Most importantly, we discovered a number of novel C. neoformans genes, the expression of which was modulated by gamma radiation exposure, and their deletion rendered cells susceptible to gamma radiation exposure, as well as DNA damage insults. Among these genes, we found that a unique transcription factor containing the basic leucine zipper domain, named Bdr1, served as a regulator of the gamma radiation resistance of C. neoformans by controlling expression of DNA repair genes, and its expression was regulated by the evolutionarily conserved DNA damage response protein kinase Rad53. Taken together, the current transcriptome and functional analyses contribute to the understanding of the unique molecular mechanism of the radiation-resistant fungus C. neoformans IMPORTANCE: Although there are no natural environments under intense radiation, some living organisms have been found to show high radiation resistance. Organisms harboring the ability of radiation resistance have unique regulatory networks to overcome this stress. Cryptococcus neoformans is one of the radiation-resistant fungi and is found in highly radioactive environments. However, it remains elusive how radiation-resistant eukaryotic microorganisms work differentially from radiation-sensitive ones. Here, we performed transcriptome analysis of C. neoformans to explore gene expression profiles after gamma radiation exposure and functionally characterized some of identified radiation resistance genes. Notably, we identified a novel regulator of radiation resistance, named Bdr1 (a bZIP TF for DNA damage response 1), which is a transcription factor (TF) that is not closely homologous to any known TF and is transcriptionally controlled by the Rad53 kinase. Therefore, our work could shed light on understanding not only the radiation response but also the radiation resistance mechanism of C. neoformans. Copyright © 2016 Jung et al.

Determination of the optimum-size californium-252 neutron source for borehole capture gamma-ray analysis

USGS Publications Warehouse

Senftle, F.E.; Macy, R.J.; Mikesell, J.L.

1979-01-01

The fast- and thermal-neutron fluence rates from a 3.7 ??g 252Cf neutron source in a simulated borehole have been measured as a function of the source-to-detector distance using air, water, coal, iron ore-concrete mix, and dry sand as borehole media. Gamma-ray intensity measurements were made for specific spectral lines at low and high energies for the same range of source-to-detector distances in the iron ore-concrete mix and in coal. Integral gamma-ray counts across the entire spectrum were also made at each source-to-detector distance. From these data, the specific neutron-damage rate, and the critical count-rate criteria, we show that in an iron ore-concrete mix (low hydrogen concentration), 252Cf neutron sources of 2-40 ??g are suitable. The source size required for optimum gamma-ray sensitivity depends on the energy of the gamma ray being measured. In a hydrogeneous medium such as coal, similar measurements were made. The results show that sources from 2 to 20 ??g are suitable to obtain the highest gamma-ray sensitivity, again depending on the energy of the gamma ray being measured. In a hydrogeneous medium, significant improvement in sensitivity can be achieved by using faster electronics; in iron ore, it cannot. ?? 1979 North-Holland Publishing Co.

DESAlert: Enabling Real-Time Transient Follow-Up with Dark Energy Survey Data

DOE PAGES

Poci, A.; Kuehn, K.; Abbott, T.; ...

2016-09-30

Here, the Dark Energy Survey is undertaking an observational programme imaging 1/4 of the southern hemisphere sky with unprecedented photometric accuracy. In the process of observing millions of faint stars and galaxies to constrain the parameters of the dark energy equation of state, the Dark Energy Survey will obtain pre-discovery images of the regions surrounding an estimated 100 gamma-ray bursts over 5 yr. Once gamma-ray bursts are detected by, e.g., the Swift satellite, the DES data will be extremely useful for follow-up observations by the transient astronomy community. We describe a recently-commissioned suite of software that listens continuously for automatedmore » notices of gamma-ray burst activity, collates information from archival DES data, and disseminates relevant data products back to the community in near-real-time. Of particular importance are the opportunities that non-public DES data provide for relative photometry of the optical counterparts of gamma-ray bursts, as well as for identifying key characteristics (e.g., photometric redshifts) of potential gamma-ray burst host galaxies. We provide the functional details of the DESAlert software, and its data products, and we show sample results from the application of DESAlert to numerous previously detected gamma-ray bursts, including the possible identification of several heretofore unknown gamma-ray burst hosts.« less

DESAlert: Enabling Real-Time Transient Follow-Up with Dark Energy Survey Data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poci, A.; Kuehn, K.; Abbott, T.

Here, the Dark Energy Survey is undertaking an observational programme imaging 1/4 of the southern hemisphere sky with unprecedented photometric accuracy. In the process of observing millions of faint stars and galaxies to constrain the parameters of the dark energy equation of state, the Dark Energy Survey will obtain pre-discovery images of the regions surrounding an estimated 100 gamma-ray bursts over 5 yr. Once gamma-ray bursts are detected by, e.g., the Swift satellite, the DES data will be extremely useful for follow-up observations by the transient astronomy community. We describe a recently-commissioned suite of software that listens continuously for automatedmore » notices of gamma-ray burst activity, collates information from archival DES data, and disseminates relevant data products back to the community in near-real-time. Of particular importance are the opportunities that non-public DES data provide for relative photometry of the optical counterparts of gamma-ray bursts, as well as for identifying key characteristics (e.g., photometric redshifts) of potential gamma-ray burst host galaxies. We provide the functional details of the DESAlert software, and its data products, and we show sample results from the application of DESAlert to numerous previously detected gamma-ray bursts, including the possible identification of several heretofore unknown gamma-ray burst hosts.« less

High-energy gamma-ray and neutrino production in star-forming galaxies across cosmic time: Difficulties in explaining the IceCube data

NASA Astrophysics Data System (ADS)

Sudoh, Takahiro; Totani, Tomonori; Kawanaka, Norita

2018-06-01

We present new theoretical modeling to predict the luminosity and spectrum of gamma-ray and neutrino emission of a star-forming galaxy, from the star formation rate (ψ), gas mass (Mgas), stellar mass, and disk size, taking into account production, propagation, and interactions of cosmic rays. The model reproduces the observed gamma-ray luminosities of nearby galaxies detected by Fermi better than the simple power-law models as a function of ψ or ψMgas. This model is then used to predict the cosmic background flux of gamma-rays and neutrinos from star-forming galaxies, by using a semi-analytical model of cosmological galaxy formation that reproduces many observed quantities of local and high-redshift galaxies. Calibration of the model using gamma-ray luminosities of nearby galaxies allows us to make a more reliable prediction than previous studies. In our baseline model, star-forming galaxies produce about 20% of the isotropic gamma-ray background unresolved by Fermi, and only 0.5% of IceCube neutrinos. Even with an extreme model assuming a hard injection cosmic-ray spectral index of 2.0 for all galaxies, at most 22% of IceCube neutrinos can be accounted for. These results indicate that it is difficult to explain most of the IceCube neutrinos by star-forming galaxies, without violating the gamma-ray constraints from nearby galaxies.

Neural correlates of high-gamma oscillations (60–200 Hz) in macaque local field potentials and their potential implications in electrocorticography

PubMed Central

Crone, Nathan E.; Niebur, Ernst; Franaszczuk, Piotr J.; Hsiao, Steven S.

2009-01-01

Recent studies using electrocorticographic (ECoG) recordings in humans have shown that functional activation of cortex is associated with an increase in power in the high-gamma frequency range (∼60–200 Hz). Here we investigate the neural correlates of this high-gamma activity in local field potential (LFP). Single units and LFP were recorded with microelectrodes from the hand region of macaque SII cortex while vibrotactile stimuli of varying intensities were presented to the hand. We found that high-gamma power in the LFP was strongly correlated with the average firing rate recorded by the microelectrodes, both temporally and on a trial-by-trial basis. In comparison, the correlation between firing rate and low-gamma power (40–80 Hz) was much smaller. In order to explore the potential effects of neuronal firing on ECoG, we developed a model to estimate ECoG power generated by different firing patterns of the underlying cortical population and studied how ECoG power varies with changes in firing rate versus the degree of synchronous firing between neurons in the population. Both an increase in firing rate and neuronal synchrony increased high-gamma power in the simulated ECoG data. However, ECoG high-gamma activity was much more sensitive to increases in neuronal synchrony than firing rate. PMID:18987189

High-energy gamma-ray and neutrino production in star-forming galaxies across cosmic time: Difficulties in explaining the IceCube data

NASA Astrophysics Data System (ADS)

Sudoh, Takahiro; Totani, Tomonori; Kawanaka, Norita

2018-04-01

We present new theoretical modeling to predict the luminosity and spectrum of gamma-ray and neutrino emission of a star-forming galaxy, from the star formation rate (ψ), gas mass (Mgas), stellar mass, and disk size, taking into account production, propagation, and interactions of cosmic rays. The model reproduces the observed gamma-ray luminosities of nearby galaxies detected by Fermi better than the simple power-law models as a function of ψ or ψMgas. This model is then used to predict the cosmic background flux of gamma-rays and neutrinos from star-forming galaxies, by using a semi-analytical model of cosmological galaxy formation that reproduces many observed quantities of local and high-redshift galaxies. Calibration of the model using gamma-ray luminosities of nearby galaxies allows us to make a more reliable prediction than previous studies. In our baseline model, star-forming galaxies produce about 20% of the isotropic gamma-ray background unresolved by Fermi, and only 0.5% of IceCube neutrinos. Even with an extreme model assuming a hard injection cosmic-ray spectral index of 2.0 for all galaxies, at most 22% of IceCube neutrinos can be accounted for. These results indicate that it is difficult to explain most of the IceCube neutrinos by star-forming galaxies, without violating the gamma-ray constraints from nearby galaxies.

High-energy gamma-ray emission from pion decay in a solar flare magnetic loop

NASA Technical Reports Server (NTRS)

Mandzhavidze, Natalie; Ramaty, Reuven

1992-01-01

The production of high-energy gamma rays resulting from pion decay in a solar flare magnetic loop is investigated. Magnetic mirroring, MHD pitch-angle scattering, and all of the relevant loss processes and photon production mechanisms are taken into account. The transport of both the primary ions and the secondary positrons resulting from the decay of the positive pions, as well as the transport of the produced gamma-ray emission are considered. The distributions of the gamma rays as a function of atmospheric depth, time, emission angle, and photon energy are calculated and the dependence of these distributions on the model parameters are studied. The obtained angular distributions are not sufficiently anisotropic to account for the observed limb brightening of the greater than 10 MeV flare emission, indicating that the bulk of this emission is bremsstrahlung from primary electrons.

Secondary gamma-ray production in a coded aperture mask

NASA Technical Reports Server (NTRS)

Owens, A.; Frye, G. M., Jr.; Hall, C. J.; Jenkins, T. L.; Pendleton, G. N.; Carter, J. N.; Ramsden, D.; Agrinier, B.; Bonfand, E.; Gouiffes, C.

1985-01-01

The application of the coded aperture mask to high energy gamma-ray astronomy will provide the capability of locating a cosmic gamma-ray point source with a precision of a few arc-minutes above 20 MeV. Recent tests using a mask in conjunction with drift chamber detectors have shown that the expected point spread function is achieved over an acceptance cone of 25 deg. A telescope employing this technique differs from a conventional telescope only in that the presence of the mask modifies the radiation field in the vicinity of the detection plane. In addition to reducing the primary photon flux incident on the detector by absorption in the mask elements, the mask will also be a secondary radiator of gamma-rays. The various background components in a CAMTRAC (Coded Aperture Mask Track Chamber) telescope are considered. Monte-Carlo calculations are compared with recent measurements obtained using a prototype instrument in a tagged photon beam line.

Performance of multi-hop parallel free-space optical communication over gamma-gamma fading channel with pointing errors.

PubMed

Gao, Zhengguang; Liu, Hongzhan; Ma, Xiaoping; Lu, Wei

2016-11-10

Multi-hop parallel relaying is considered in a free-space optical (FSO) communication system deploying binary phase-shift keying (BPSK) modulation under the combined effects of a gamma-gamma (GG) distribution and misalignment fading. Based on the best path selection criterion, the cumulative distribution function (CDF) of this cooperative random variable is derived. Then the performance of this optical mesh network is analyzed in detail. A Monte Carlo simulation is also conducted to demonstrate the effectiveness of the results for the average bit error rate (ABER) and outage probability. The numerical result proves that it needs a smaller average transmitted optical power to achieve the same ABER and outage probability when using the multi-hop parallel network in FSO links. Furthermore, the system use of more number of hops and cooperative paths can improve the quality of the communication.

A quantitative theory of gamma synchronization in macaque V1.

PubMed

Lowet, Eric; Roberts, Mark J; Peter, Alina; Gips, Bart; De Weerd, Peter

2017-08-31

Gamma-band synchronization coordinates brief periods of excitability in oscillating neuronal populations to optimize information transmission during sensation and cognition. Commonly, a stable, shared frequency over time is considered a condition for functional neural synchronization. Here, we demonstrate the opposite: instantaneous frequency modulations are critical to regulate phase relations and synchronization. In monkey visual area V1, nearby local populations driven by different visual stimulation showed different gamma frequencies. When similar enough, these frequencies continually attracted and repulsed each other, which enabled preferred phase relations to be maintained in periods of minimized frequency difference. Crucially, the precise dynamics of frequencies and phases across a wide range of stimulus conditions was predicted from a physics theory that describes how weakly coupled oscillators influence each other's phase relations. Hence, the fundamental mathematical principle of synchronization through instantaneous frequency modulations applies to gamma in V1 and is likely generalizable to other brain regions and rhythms.

Data analysis of the COMPTEL instrument on the NASA gamma ray observatory

NASA Technical Reports Server (NTRS)

Diehl, R.; Bennett, K.; Collmar, W.; Connors, A.; Denherder, J. W.; Hermsen, W.; Lichti, G. G.; Lockwood, J. A.; Macri, J.; Mcconnell, M.

1992-01-01

The Compton imaging telescope (COMPTEL) on the Gamma Ray Observatory (GRO) is a wide field of view instrument. The coincidence measurement technique in two scintillation detector layers requires specific analysis methods. Straightforward event projection into the sky is impossible. Therefore, detector events are analyzed in a multi-dimensional dataspace using a gamma ray sky hypothesis convolved with the point spread function of the instrument in this dataspace. Background suppression and analysis techniques have important implications on the gamma ray source results for this background limited telescope. The COMPTEL collaboration applies a software system of analysis utilities, organized around a database management system. The use of this system for the assistance of guest investigators at the various collaboration sites and external sites is foreseen and allows different detail levels of cooperation with the COMPTEL institutes, dependent on the type of data to be studied.

Transforming growth factor-beta controls T helper type 1 cell development through regulation of natural killer cell interferon-gamma.

PubMed

Laouar, Yasmina; Sutterwala, Fayyaz S; Gorelik, Leonid; Flavell, Richard A

2005-06-01

Interferon-gamma and interleukin 12 produced by the innate arm of the immune system are important regulators of T helper type 1 (T(H)1) cell development, but signals that negatively regulate their expression remain controversial. Here we show that transforming growth factor-beta (TGF-beta) controlled T(H)1 differentiation through the regulation of interferon-gamma produced by natural killer (NK) cells. Blockade of TGF-beta signaling in NK cells caused the accumulation of a large pool of NK cells secreting copious interferon-gamma, responsible for T(H)1 differentiation and protection from leishmania infection. In contrast, blockade of TGF-beta signaling in dendritic cells did not affect dendritic cell homeostasis or interleukin 12 production, thus indicating a previously undescribed demarcation of the function of TGF-beta in NK cells versus dendritic cells.

SER Analysis of MPPM-Coded MIMO-FSO System over Uncorrelated and Correlated Gamma-Gamma Atmospheric Turbulence Channels

NASA Astrophysics Data System (ADS)

Khallaf, Haitham S.; Garrido-Balsells, José M.; Shalaby, Hossam M. H.; Sampei, Seiichi

2015-12-01

The performance of multiple-input multiple-output free space optical (MIMO-FSO) communication systems, that adopt multipulse pulse position modulation (MPPM) techniques, is analyzed. Both exact and approximate symbol-error rates (SERs) are derived for both cases of uncorrelated and correlated channels. The effects of background noise, receiver shot-noise, and atmospheric turbulence are taken into consideration in our analysis. The random fluctuations of the received optical irradiance, produced by the atmospheric turbulence, is modeled by the widely used gamma-gamma statistical distribution. Uncorrelated MIMO channels are modeled by the α-μ distribution. A closed-form expression for the probability density function of the optical received irradiance is derived for the case of correlated MIMO channels. Using our analytical expressions, the degradation of the system performance with the increment of the correlation coefficients between MIMO channels is corroborated.

Design optimization for a wearable, gamma-ray and neutron sensitive, detector array with directionality estimation

NASA Astrophysics Data System (ADS)

Ayaz-Maierhafer, Birsen; Britt, Carl G.; August, Andrew J.; Qi, Hairong; Seifert, Carolyn E.; Hayward, Jason P.

2017-10-01

In this study, we report on a constrained optimization and tradeoff study of a hybrid, wearable detector array having directional sensing based upon gamma-ray occlusion. One resulting design uses CLYC detectors while the second feasibility design involves the coupling of gamma-ray-sensitive CsI scintillators and a rubber LiCaAlF6 (LiCAF) neutron detector. The detector systems' responses were investigated through simulation as a function of angle in a two-dimensional plane. The expected total counts, peak-to-total ratio, directionality performance, and detection of 40 K for accurate gain stabilization were considered in the optimization. Source directionality estimation was investigated using Bayesian algorithms. Gamma-ray energies of 122 keV, 662 keV, and 1332 keV were considered. The equivalent neutron capture response compared with 3 He was also investigated for both designs.

A quantitative theory of gamma synchronization in macaque V1

PubMed Central

Roberts, Mark J; Peter, Alina; Gips, Bart; De Weerd, Peter

2017-01-01

Gamma-band synchronization coordinates brief periods of excitability in oscillating neuronal populations to optimize information transmission during sensation and cognition. Commonly, a stable, shared frequency over time is considered a condition for functional neural synchronization. Here, we demonstrate the opposite: instantaneous frequency modulations are critical to regulate phase relations and synchronization. In monkey visual area V1, nearby local populations driven by different visual stimulation showed different gamma frequencies. When similar enough, these frequencies continually attracted and repulsed each other, which enabled preferred phase relations to be maintained in periods of minimized frequency difference. Crucially, the precise dynamics of frequencies and phases across a wide range of stimulus conditions was predicted from a physics theory that describes how weakly coupled oscillators influence each other’s phase relations. Hence, the fundamental mathematical principle of synchronization through instantaneous frequency modulations applies to gamma in V1 and is likely generalizable to other brain regions and rhythms. PMID:28857743

Performance analysis of OOK-based FSO systems in Gamma-Gamma turbulence with imprecise channel models

NASA Astrophysics Data System (ADS)

Feng, Jianfeng; Zhao, Xiaohui

2017-11-01

For an FSO communication system with imprecise channel model, we investigate its system performance based on outage probability, average BEP and ergodic capacity. The exact FSO links are modeled as Gamma-Gamma fading channel in consideration of both atmospheric turbulence and pointing errors, and the imprecise channel model is treated as the superposition of exact channel gain and a Gaussian random variable. After we derive the PDF, CDF and nth moment of the imprecise channel gain, and based on these statistics the expressions for the outage probability, the average BEP and the ergodic capacity in terms of the Meijer's G functions are obtained. Both numerical and analytical results are presented. The simulation results show that the communication performance deteriorates in the imprecise channel model, and approaches to the exact performance curves as the channel model becomes accurate.

Viscoelastic Timoshenko Beams with Occasionally Constant Relaxation Functions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tatar, Nasser-eddine, E-mail: tatarn@kfupm.edu.sa

2012-08-15

For a prescribed desirable arbitrary decay suitable viscoelastic materials are determined through their relaxation functions. It is shown that if we wish to have a decay of order {gamma}(t) then the kernels should be of the same order. That is their product with this function should be summable.

Immunological studies on the structure and function of the nicotinic acetylcholine receptor in mammalian muscle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gu, Y.

1989-01-01

The specificity of the antibodies in the serum of a patient with myasthenia gravis for a the {alpha}-bungarotoxin binding sites of the acetylcholine receptor (AChR) was examined using AChRs in the C2 mouse muscle cell line as a model. The antibodies were shown to be specific for one of the two toxin-binding sites. The effect of the antibodies in this myasthenic serum on the functional response of the receptor to cholinergic agonists was also examined using carbamylcholine-induced {sup 22}Na uptake into C2 myotubes as a measured of the receptor function. Antibodies specific for the {gamma}, {delta}, and {epsilon} subunit, respectively,more » of mammalian muscle AChRs were developed using subunit-specific synthetic peptides as antigens. Using these antibodies and monoclonal antibodies for other subunits as probes, I have identified four ({alpha}, {beta}, {gamma}, and {delta}) subunits of mammalian muscle AChRs on immunoblots. When AChRs from embryonic, neonatal, normal and denervated adult muscles were compared on immunoblots, the {alpha}, {beta}, and {delta} subunits were identical in all four receptor preparations, with or without endoglycosidase digestion. The spatial and temporal distribution of the {gamma}- and {epsilon}- AChRs in developing and in denervated muscles corresponds to the distribution of AChRs with slow and fast channels, respectively, and that the development changes in the channel properties of the receptor arise from a change in the subunit composition of the receptor, in which the {gamma} is replaced by {epsilon}.« less

Functional relationships of landfill and landraise capacity with design and operation parameters.

PubMed

Aivaliotis, Vassilis; Dokas, Ioannis; Hatzigiannakou, Maria; Panagiotakopoulos, Demetrios

2004-08-01

Solid waste management presses for effective landfill design and operation. While planning and operating a landfill (LF) or a landraise (LR), choices need to be made regarding: (1) LF-LR morphology (base shape, side slopes, final cover thickness, LR/LF height/depth); (2) cell geometry (height, length, slopes); and (3) operation parameters (waste density, working face length, cover thicknesses). These parameters affect LF/LR capacity, operation lifespan and construction/ operation costs. In this paper, relationships are generated between capacity (C, space available for waste) and the above parameters. Incorporating real data into simulation kgamma A1.38, runs, two types of functions are developed: first, C = where A is the LF/LR base area size and kgamma a base shape-dependent coefficient; and second, C = alpha(p,gamma,A) + delta(p,gamma,A)Xp for every parameter p, where Xp is the value of p and alpha(p,gamma,A) and delta(p,gamma,A) are parameter- and base (shape/size)-specific coefficients. Moreover, the relationship between LF depth and LR height that balances excavation volume with cover material, is identified. Another result is that, for a symmetrical combination of LF/LR, with base surface area shape between square and 1:2 orthogonal, and final density between 500 and 800 kg m(-3), waste quantity placed ranges from 1.76A1.38 to 2.55A1.38 tons. The significance of such functions is obvious, as they allow the analyst to investigate alternative LF/LR schemes and make trade-off analyses.

Mid-term prognosis of non-functioning pituitary adenomas with high proliferative potential: really an aggressive variant?

PubMed

Ogawa, Yoshikazu; Jokura, Hidefumi; Niizuma, Kuniyasu; Tominaga, Teiji

2018-05-01

Pituitary adenomas with high proliferation rate and rapid growth are well known, but the clinical characteristics, prognosis, and treatment algorithm remain unclear. The clinical characteristics and mid-term prognosis of patients with non-functioning pituitary adenomas with high proliferative potential were retrospectively investigated. This study identified 53 patients with Ki-67 labeling index of > 3% among 845 patients with non-functioning pituitary adenoma (6.3%) initially treated by surgery. Prophylactic treatment was not applied for patients with residual tumor, but salvage treatment was performed if tumor progression was identified within the follow-up period. Twenty-two patients remained progression-free, whereas 31 patients suffered tumor progression. Comparison of gross total removal (n = 22) and non-total removal (n = 31) groups showed significantly longer progression-free period in the former group (P < 0.001). As salvage treatment gamma knife radiosurgery was applied for 11 patients resulting in 10 patients remaining progression-free and regrowth in 1 patient. Fractionated irradiation was applied for 10 patients, resulting in 2 patients remaining progression-free, deaths in 5 patients including 3 of transformation to pituitary carcinoma, dementia in 1 patient caused by frontal lobe dysfunction, and progression in 2 patients requiring additional surgery and gamma knife radiosurgery. Temozolomide was administered in 2 patients, resulting in deaths in both patients including 1 transformation to pituitary carcinoma. Total removal and gamma knife radiosurgery can result in good outcome. However, the prognosis is extremely poor for patients inadequate for gamma knife radiosurgery. Development of new salvage treatments is essential.

Brain responses to 40-Hz binaural beat and effects on emotion and memory.

PubMed

Jirakittayakorn, Nantawachara; Wongsawat, Yodchanan

2017-10-01

Gamma oscillation plays a role in binding process or sensory integration, a process by which several brain areas beside primary cortex are activated for higher perception of the received stimulus. Beta oscillation is also involved in interpreting received stimulus and occurs following gamma oscillation, and this process is known as gamma-to-beta transition, a process for neglecting unnecessary stimuli in surrounding environment. Gamma oscillation also associates with cognitive functions, memory and emotion. Therefore, modulation of the brain activity can lead to manipulation of cognitive functions. The stimulus used in this study was 40-Hz binaural beat because binaural beat induces frequency following response. This study aimed to investigate the neural oscillation responding to the 40-Hz binaural beat and to evaluate working memory function and emotional states after listening to that stimulus. Two experiments were developed based on the study aims. In the first experiment, electroencephalograms were recorded while participants listened to the stimulus for 30min. The results suggested that frontal, temporal, and central regions were activated within 15min. In the second experiment, word list recall task was conducted before and after listening to the stimulus for 20min. The results showed that, after listening, the recalled words were increase in the working memory portion of the list. Brunel Mood Scale, a questionnaire to evaluate emotional states, revealed changes in emotional states after listening to the stimulus. The emotional results suggested that these changes were consistent with the induced neural oscillations. Copyright © 2017 Elsevier B.V. All rights reserved.

Modulation of hippocampal rhythms by subthreshold electric fields and network topology

PubMed Central

Berzhanskaya, Julia; Chernyy, Nick; Gluckman, Bruce J.; Schiff, Steven J.; Ascoli, Giorgio A.

2012-01-01

Theta (4–12 Hz) and gamma (30–80 Hz) rhythms are considered important for cortical and hippocampal function. Although several neuron types are implicated in rhythmogenesis, the exact cellular mechanisms remain unknown. Subthreshold electric fields provide a flexible, area-specific tool to modulate neural activity and directly test functional hypotheses. Here we present experimental and computational evidence of the interplay among hippocampal synaptic circuitry, neuronal morphology, external electric fields, and network activity. Electrophysiological data are used to constrain and validate an anatomically and biophysically realistic model of area CA1 containing pyramidal cells and two interneuron types: dendritic- and perisomatic-targeting. We report two lines of results: addressing the network structure capable of generating theta-modulated gamma rhythms, and demonstrating electric field effects on those rhythms. First, theta-modulated gamma rhythms require specific inhibitory connectivity. In one configuration, GABAergic axo-dendritic feedback on pyramidal cells is only effective in proximal but not distal layers. An alternative configuration requires two distinct perisomatic interneuron classes, one exclusively receiving excitatory contacts, the other additionally targeted by inhibition. These observations suggest novel roles for particular classes of oriens and basket cells. The second major finding is that subthreshold electric fields robustly alter the balance between different rhythms. Independent of network configuration, positive electric fields decrease, while negative fields increase the theta/gamma ratio. Moreover, electric fields differentially affect average theta frequency depending on specific synaptic connectivity. These results support the testable prediction that subthreshold electric fields can alter hippocampal rhythms, suggesting new approaches to explore their cognitive functions and underlying circuitry. PMID:23053863

Crystal structure of human complement protein C8{gamma} at 1.2 {Angstrom} resolution reveals a lipocalin fold and a distinct ligand binding site.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ortlund, E.; Parker, C. L.; Schreck, A. F.

2002-01-01

C8gamma is a 22-kDa subunit of human C8, which is one of five components of the cytolytic membrane attack complex of complement (MAC). C8gamma is disulfide-linked to a C8alpha subunit that is noncovalently associated with a C8beta chain. In the present study, the three-dimensional structure of recombinant C8gamma was determined by X-ray diffraction to 1.2 A resolution. The structure displays a typical lipocalin fold forming a calyx with a distinct binding pocket that is indicative of a ligand-binding function for C8gamma. When compared to other lipocalins, the overall structure is most similar to neutrophil gelatinase associated lipocalin (NGAL), a proteinmore » released from granules of activated neutrophils. Notable differences include a much deeper binding pocket in C8gamma as well as variation in the identity and position of residues lining the pocket. In C8gamma, these residues allow ligand access to a large hydrophobic cavity at the base of the calyx, whereas corresponding residues in NGAL restrict access. This suggests the natural ligands for C8gamma and NGAL are significantly different in size. Cys40 in C8gamma, which forms the disulfide bond to C8alpha, is located in a partially disordered loop (loop 1, residues 38-52) near the opening of the calyx. Access to the calyx may be regulated by movement of this loop in response to conformational changes in C8alpha during MAC formation.« less

Nonuniform High-Gamma (60–500 Hz) Power Changes Dissociate Cognitive Task and Anatomy in Human Cortex

PubMed Central

Gaona, Charles M.; Sharma, Mohit; Freudenburg, Zachary V.; Breshears, Jonathan D.; Bundy, David T.; Roland, Jarod; Barbour, Dennis L.; Schalk, Gerwin

2011-01-01

High-gamma-band (>60 Hz) power changes in cortical electrophysiology are a reliable indicator of focal, event-related cortical activity. Despite discoveries of oscillatory subthreshold and synchronous suprathreshold activity at the cellular level, there is an increasingly popular view that high-gamma-band amplitude changes recorded from cellular ensembles are the result of asynchronous firing activity that yields wideband and uniform power increases. Others have demonstrated independence of power changes in the low- and high-gamma bands, but to date, no studies have shown evidence of any such independence above 60 Hz. Based on nonuniformities in time-frequency analyses of electrocorticographic (ECoG) signals, we hypothesized that induced high-gamma-band (60–500 Hz) power changes are more heterogeneous than currently understood. Using single-word repetition tasks in six human subjects, we showed that functional responsiveness of different ECoG high-gamma sub-bands can discriminate cognitive task (e.g., hearing, reading, speaking) and cortical locations. Power changes in these sub-bands of the high-gamma range are consistently present within single trials and have statistically different time courses within the trial structure. Moreover, when consolidated across all subjects within three task-relevant anatomic regions (sensorimotor, Broca's area, and superior temporal gyrus), these behavior- and location-dependent power changes evidenced nonuniform trends across the population. Together, the independence and nonuniformity of power changes across a broad range of frequencies suggest that a new approach to evaluating high-gamma-band cortical activity is necessary. These findings show that in addition to time and location, frequency is another fundamental dimension of high-gamma dynamics. PMID:21307246

5-Hydroxytryptamine1A receptor-activation hyperpolarizes pyramidal cells and suppresses hippocampal gamma oscillations via Kir3 channel activation

PubMed Central

Johnston, April; McBain, Chris J; Fisahn, André

2014-01-01

Rhythmic cortical neuronal oscillations in the gamma frequency band (30–80 Hz, gamma oscillations) have been associated with cognitive processes such as sensory perception and integration, attention, learning, and memory. Gamma oscillations are disrupted in disorders for which cognitive deficits are hallmark symptoms such as schizophrenia and Alzheimer's disease. In vitro, various neurotransmitters have been found to modulate gamma oscillations. Serotonin (5-HT) has long been known to be important for both behavioural and cognitive functions such as learning and memory. Multiple 5-HT receptor subtypes are expressed in the CA3 region of the hippocampus and high doses of 5-HT reduce the power of induced gamma oscillations. Hypothesizing that 5-HT may have cell- and receptor subtype-specific modulatory effects, we investigated the receptor subtypes, cell types and cellular mechanisms engaged by 5-HT in the modulation of gamma oscillations in mice and rats. We found that 5-HT decreases the power of kainate-induced hippocampal gamma oscillations in both species via the 5-HT1A receptor subtype. Whole-cell patch clamp recordings demonstrated that this decrease was caused by a hyperpolarization of CA3 pyramidal cells and a reduction of their firing frequency, but not by alteration of inhibitory neurotransmission. Finally, our results show that the effect on pyramidal cells is mediated via the G protein-coupled receptor inwardly rectifying potassium channel Kir3. Our findings suggest this novel cellular mechanism as a potential target for therapies that are aimed at alleviating cognitive decline by helping the brain to maintain or re-establish normal gamma oscillation levels in neuropsychiatric and neurodegenerative disorders. PMID:25107925

THE LUMINOSITY FUNCTION OF FERMI-DETECTED FLAT-SPECTRUM RADIO QUASARS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ajello, M.; Shaw, M. S.; Romani, R. W.

2012-06-01

Fermi has provided the largest sample of {gamma}-ray-selected blazars to date. In this work we use a complete sample of flat spectrum radio quasars (FSRQs) detected during the first year of operation to determine the luminosity function (LF) and its evolution with cosmic time. The number density of FSRQs grows dramatically up to redshift {approx}0.5-2.0 and declines thereafter. The redshift of the peak in the density is luminosity dependent, with more luminous sources peaking at earlier times; thus the LF of {gamma}-ray FSRQs follows a luminosity-dependent density evolution similar to that of radio-quiet active galactic nuclei. Also, using data frommore » the Swift Burst Alert Telescope we derive the average spectral energy distribution (SED) of FSRQs in the 10 keV-300 GeV band and show that there is no correlation between the luminosity at the peak of the {gamma}-ray emission component and its peak frequency. Using this luminosity-independent SED with the derived LF allows us to predict that the contribution of FSRQs to the Fermi isotropic {gamma}-ray background is 9.3{sup +1.6}{sub -1.0}% ({+-}3% systematic uncertainty) in the 0.1-100 GeV band. Finally we determine the LF of unbeamed FSRQs, finding that FSRQs have an average Lorentz factor of {gamma} = 11.7{sup +3.3}{sub -2.2}, that most are seen within 5 Degree-Sign of the jet axis, and that they represent only {approx}0.1% of the parent population.« less

Ketamine: differential neurophysiological dynamics in functional networks in the rat brain

PubMed Central

Ahnaou, A; Huysmans, H; Biermans, R; Manyakov, N V; Drinkenburg, W H I M

2017-01-01

Recently, the N-methyl-d-aspartate-receptor (NMDAR) antagonist ketamine has emerged as a fast-onset mechanism to achieve antidepressant activity, whereas its psychomimetic, dissociative and amnestic effects have been well documented to pharmacologically model schizophrenia features in rodents. Sleep–wake architecture, neuronal oscillations and network connectivity are key mechanisms supporting brain plasticity and cognition, which are disrupted in mood disorders such as depression and schizophrenia. In rats, we investigated the dynamic effects of acute and chronic subcutaneous administration of ketamine (2.5, 5 and 10 mg kg−1) on sleep–wake cycle, multichannels network interactions assessed by coherence and phase–amplitude cross-frequency coupling, locomotor activity (LMA), cognitive information processing as reflected by the mismatch negativity-like (MMN) component of event-related brain potentials (ERPs). Acute ketamine elicited a short, lasting inhibition of rapid eye movement (REM) sleep, increased coherence in higher gamma frequency oscillations independent of LMA, altered theta-gamma phase–amplitude coupling, increased MMN peak-amplitude response and evoked higher gamma oscillations. In contrast, chronic ketamine reduced large-scale communication among cortical regions by decreasing oscillations and coherent activity in the gamma frequency range, shifted networks activity towards slow alpha rhythm, decreased MMN peak response and enhanced aberrant higher gamma neuronal network oscillations. Altogether, our data show that acute and chronic ketamine elicited differential changes in network connectivity, ERPs and event-related oscillations (EROs), supporting possible underlying alterations in NMDAR–GABAergic signaling. The findings underscore the relevance of intermittent dosing of ketamine to accurately maintain the functional integrity of neuronal networks for long-term plastic changes and therapeutic effect. PMID:28926001

Mice deficient in LRG-47 display enhanced susceptibility to Trypanosoma cruzi infection associated with defective hemopoiesis and intracellular control of parasite growth.

PubMed

Santiago, Helton C; Feng, Carl G; Bafica, Andre; Roffe, Ester; Arantes, Rosa M; Cheever, Allen; Taylor, Gregory; Vieira, Leda Q; Vierira, Leda Q; Aliberti, Julio; Gazzinelli, Ricardo T; Sher, Alan

2005-12-15

IFN-gamma is known to be required for host control of intracellular Trypanosoma cruzi infection in mice, although the basis of its protective function is poorly understood. LRG-47 is an IFN-inducible p47GTPase that has been shown to regulate host resistance to intracellular pathogens. To investigate the possible role of LRG-47 in IFN-gamma-dependent control of T. cruzi infection, LRG-47 knockout (KO) and wild-type (WT) mice were infected with the Y strain of this parasite, and host responses were analyzed. When assayed on day 12 after parasite inoculation, LRG-47 KO mice, in contrast to IFN-gamma KO mice, controlled early parasitemia almost as effectively as WT animals. However, the infected LRG-47 KO mice displayed a rebound in parasite growth on day 15, and all succumbed to the infection by day 19. Additional analysis indicated that LRG-47-deficient mice exhibit unimpaired proinflammatory responses throughout the infection. Instead, reactivated disease in the KO animals was associated with severe splenic and thymic atrophy, anemia, and thrombocytopenia not observed in their WT counterparts. In addition, in vitro studies revealed that IFN-gamma-stimulated LRG-47 KO macrophages display defective intracellular killing of amastigotes despite normal expression of TNF and NO synthetase type 2 and that both NO synthetase type 2 and LRG-47 are required for optimum IFN-gamma-dependent restriction of parasite growth. Together, these data establish that LRG-47 can influence pathogen control by simultaneously regulating macrophage-microbicidal activity and hemopoietic function.

Standardized Pearson type 3 density function area tables

NASA Technical Reports Server (NTRS)

Cohen, A. C.; Helm, F. R.; Sugg, M.

1971-01-01

Tables constituting extension of similar tables published in 1936 are presented in report form. Single and triple parameter gamma functions are discussed. Report tables should interest persons concerned with development and use of numerical analysis and evaluation methods.

Chemical composition and lipoxygenase activity in soybeans (Glycine max L. Merr.) submitted to gamma irradiation

NASA Astrophysics Data System (ADS)

Barros, Érica Amanda de; Broetto, Fernando; Bressan, Dayanne F.; Sartori, Maria M. P.; Costa, Vladimir E.

2014-05-01

Soybeans are an important food due to their functional and nutritional characteristics. However, consumption by western populations is limited by the astringent taste of soybeans and their derivatives which results from the action of lipoxygenase, an enzyme activated during product processing. The aim of this study was to evaluate the effect of gamma irradiation on the chemical composition and specific activity of lipoxygenase in different soybean cultivars. Soybeans were stored in plastic bags and irradiated with doses of 2.5, 5 and 10 kGy. The chemical composition (moisture, protein, lipids, ashes, crude fiber, and carbohydrates) and lipoxygenase specific activity were determined for each sample. Gamma irradiation induced a small increase of protein and lipid content in some soybean cultivars, which did not exceed the highest content of 5% and 26%, respectively, when compared to control. Lipoxygenase specific activity decreased in the three cultivars with increasing gamma irradiation dose. In conclusion, the gamma irradiation doses used are suitable to inactivate part of lipoxygenase while not causing expressive changes in the chemical composition of the cultivars studied.

Astrocytes contribute to gamma oscillations and recognition memory.

PubMed

Lee, Hosuk Sean; Ghetti, Andrea; Pinto-Duarte, António; Wang, Xin; Dziewczapolski, Gustavo; Galimi, Francesco; Huitron-Resendiz, Salvador; Piña-Crespo, Juan C; Roberts, Amanda J; Verma, Inder M; Sejnowski, Terrence J; Heinemann, Stephen F

2014-08-12

Glial cells are an integral part of functional communication in the brain. Here we show that astrocytes contribute to the fast dynamics of neural circuits that underlie normal cognitive behaviors. In particular, we found that the selective expression of tetanus neurotoxin (TeNT) in astrocytes significantly reduced the duration of carbachol-induced gamma oscillations in hippocampal slices. These data prompted us to develop a novel transgenic mouse model, specifically with inducible tetanus toxin expression in astrocytes. In this in vivo model, we found evidence of a marked decrease in electroencephalographic (EEG) power in the gamma frequency range in awake-behaving mice, whereas neuronal synaptic activity remained intact. The reduction in cortical gamma oscillations was accompanied by impaired behavioral performance in the novel object recognition test, whereas other forms of memory, including working memory and fear conditioning, remained unchanged. These results support a key role for gamma oscillations in recognition memory. Both EEG alterations and behavioral deficits in novel object recognition were reversed by suppression of tetanus toxin expression. These data reveal an unexpected role for astrocytes as essential contributors to information processing and cognitive behavior.

Telmisartan prevented cognitive decline partly due to PPAR-{gamma} activation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mogi, Masaki; Li Jianmei; Tsukuda, Kana

Telmisartan is a unique angiotensin receptor blocker (ARB) and partial agonist of peroxisome proliferator-activated receptor (PPAR)-{gamma}. Here, we investigated the preventive effect of telmisartan on cognitive decline in Alzheimer disease. In ddY mice, intracerebroventricular injection of A{beta} 1-40 significantly attenuated their cognitive function evaluated by shuttle avoidance test. Pretreatment with a non-hypotensive dose of telmisartan significantly inhibited such cognitive decline. Interestingly, co-treatment with GW9662, a PPAR-{gamma} antagonist, partially inhibited this improvement of cognitive decline. Another ARB, losartan, which has less PPAR-{gamma} agonistic effect, also inhibited A{beta}-injection-induced cognitive decline; however the effect was smaller than that of telmisartan and was notmore » affected by GW9662. Immunohistochemical staining for A{beta} showed the reduced A{beta} deposition in telmisartan-treated mice. However, this reduction was not observed in mice co-administered GW9662. These findings suggest that ARB has a preventive effect on cognitive impairment in Alzheimer disease, and telmisartan, with PPAR-{gamma} activation, could exert a stronger effect.« less

Integral-moment analysis of the BATSE gamma-ray burst intensity distribution

NASA Technical Reports Server (NTRS)

Horack, John M.; Emslie, A. Gordon

1994-01-01

We have applied the technique of integral-moment analysis to the intensity distribution of the first 260 gamma-ray bursts observed by the Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory. This technique provides direct measurement of properties such as the mean, variance, and skewness of the convolved luminosity-number density distribution, as well as associated uncertainties. Using this method, one obtains insight into the nature of the source distributions unavailable through computation of traditional single parameters such as V/V(sub max)). If the luminosity function of the gamma-ray bursts is strongly peaked, giving bursts only a narrow range of luminosities, these results are then direct probes of the radial distribution of sources, regardless of whether the bursts are a local phenomenon, are distributed in a galactic halo, or are at cosmological distances. Accordingly, an integral-moment analysis of the intensity distribution of the gamma-ray bursts provides for the most complete analytic description of the source distribution available from the data, and offers the most comprehensive test of the compatibility of a given hypothesized distribution with observation.

Clustering of gamma-ray burst types in the Fermi GBM catalogue: indications of photosphere and synchrotron emissions during the prompt phase

NASA Astrophysics Data System (ADS)

Acuner, Zeynep; Ryde, Felix

2018-04-01

Many different physical processes have been suggested to explain the prompt gamma-ray emission in gamma-ray bursts (GRBs). Although there are examples of both bursts with photospheric and synchrotron emission origins, these distinct spectral appearances have not been generalized to large samples of GRBs. Here, we search for signatures of the different emission mechanisms in the full Fermi Gamma-ray Space Telescope/GBM (Gamma-ray Burst Monitor) catalogue. We use Gaussian Mixture Models to cluster bursts according to their parameters from the Band function (α, β, and Epk) as well as their fluence and T90. We find five distinct clusters. We further argue that these clusters can be divided into bursts of photospheric origin (2/3 of all bursts, divided into three clusters) and bursts of synchrotron origin (1/3 of all bursts, divided into two clusters). For instance, the cluster that contains predominantly short bursts is consistent of photospheric emission origin. We discuss several reasons that can determine which cluster a burst belongs to: jet dissipation pattern and/or the jet content, or viewing angle.

Studying the response of a plastic scintillator to gamma rays using the Geant4 Monte Carlo code.

PubMed

Ghadiri, Rasoul; Khorsandi, Jamshid

2015-05-01

To determine the gamma ray response function of an NE-102 scintillator and to investigate the gamma spectra due to the transport of optical photons, we simulated an NE-102 scintillator using Geant4 code. The results of the simulation were compared with experimental data. Good consistency between the simulation and data was observed. In addition, the time and spatial distributions, along with the energy distribution and surface treatments of scintillation detectors, were calculated. This simulation makes us capable of optimizing the photomultiplier tube (or photodiodes) position to yield the best coupling to the detector. Copyright © 2015 Elsevier Ltd. All rights reserved.

Gamma irradiator dose mapping simulation using the MCNP code and benchmarking with dosimetry.

PubMed

Sohrabpour, M; Hassanzadeh, M; Shahriari, M; Sharifzadeh, M

2002-10-01

The Monte Carlo transport code, MCNP, has been applied in simulating dose rate distribution in the IR-136 gamma irradiator system. Isodose curves, cumulative dose values, and system design data such as throughputs, over-dose-ratios, and efficiencies have been simulated as functions of product density. Simulated isodose curves, and cumulative dose values were compared with dosimetry values obtained using polymethyle-methacrylate, Fricke, ethanol-chlorobenzene, and potassium dichromate dosimeters. The produced system design data were also found to agree quite favorably with those of the system manufacturer's data. MCNP has thus been found to be an effective transport code for handling of various dose mapping excercises for gamma irradiators.

A covariant model for the gamma N -> N(1535) transition at high momentum transfer

DOE Office of Scientific and Technical Information (OSTI.GOV)

G. Ramalho, M.T. Pena

2011-08-01

A relativistic constituent quark model is applied to the gamma N -> N(1535) transition. The N(1535) wave function is determined by extending the covariant spectator quark model, previously developed for the nucleon, to the S11 resonance. The model allows us to calculate the valence quark contributions to the gamma N -> N(1535) transition form factors. Because of the nucleon and N(1535) structure the model is valid only for Q^2> 2.3 GeV^2. The results are compared with the experimental data for the electromagnetic form factors F1* and F2* and the helicity amplitudes A_1/2 and S_1/2, at high Q^2.

SMM observation of a cosmic gamma-ray burst from 20 keV to 100 MeV

NASA Technical Reports Server (NTRS)

Share, G. H.; Matz, S. M.; Messina, D. C.; Nolan, P. L.; Chupp, E. L.

1986-01-01

The Solar Maximum Mission gamma-ray spectrometer has detected an intense gamma-ray burst that occurred on August 5, 1984. The burst originated from a source in the constellation Hydra and lasted about 45 s. Its integral fluence at 20 keV was 0.003 erg/sq cm. Spectral evolution similar to other bursts detected by SMM was observed. The overall shape of the spectrum from 20 keV to 100 MeV, on timescales as short as 2 s, is relatively constant. This shape can be fitted by the sum of an exponential-type function and a power law. There is no evidence for narrow or broadened emission lines.

Measurement of inclusive jet cross sections in Z/gamma*(-->e+e-) + jets production in pp[over ] collisions at square root s = 1.96 TeV.

PubMed

Aaltonen, T; Adelman, J; Akimoto, T; Albrow, M G; Alvarez González, B; Amerio, S; Amidei, D; Anastassov, A; Annovi, A; Antos, J; Aoki, M; Apollinari, G; Apresyan, A; Arisawa, T; Artikov, A; Ashmanskas, W; Attal, A; Aurisano, A; Azfar, F; Azzi-Bacchetta, P; Azzurri, P; Bacchetta, N; Badgett, W; Barbaro-Galtieri, A; Barnes, V E; Barnett, B A; Baroiant, S; Bartsch, V; Bauer, G; Beauchemin, P-H; Bedeschi, F; Bednar, P; Behari, S; Bellettini, G; Bellinger, J; Belloni, A; Benjamin, D; Beretvas, A; Beringer, J; Berry, T; Bhatti, A; Binkley, M; Bisello, D; Bizjak, I; Blair, R E; Blocker, C; Blumenfeld, B; Bocci, A; Bodek, A; Boisvert, V; Bolla, G; Bolshov, A; Bortoletto, D; Boudreau, J; Boveia, A; Brau, B; Bridgeman, A; Brigliadori, L; Bromberg, C; Brubaker, E; Budagov, J; Budd, H S; Budd, S; Burkett, K; Busetto, G; Bussey, P; Buzatu, A; Byrum, K L; Cabrera, S; Campanelli, M; Campbell, M; Canelli, F; Canepa, A; Carlsmith, D; Carosi, R; Carrillo, S; Carron, S; Casal, B; Casarsa, M; Castro, A; Catastini, P; Cauz, D; Cavalli-Sforza, M; Cerri, A; Cerrito, L; Chang, S H; Chen, Y C; Chertok, M; Chiarelli, G; Chlachidze, G; Chlebana, F; Cho, K; Chokheli, D; Chou, J P; Choudalakis, G; Chuang, S H; Chung, K; Chung, W H; Chung, Y S; Ciobanu, C I; Ciocci, M A; Clark, A; Clark, D; Compostella, G; Convery, M E; Conway, J; Cooper, B; Copic, K; Cordelli, M; Cortiana, G; Crescioli, F; Cuenca Almenar, C; Cuevas, J; Culbertson, R; Cully, J C; Dagenhart, D; Datta, M; Davies, T; de Barbaro, P; De Cecco, S; Deisher, A; De Lentdecker, G; De Lorenzo, G; Dell'orso, M; Demortier, L; Deng, J; Deninno, M; De Pedis, D; Derwent, P F; Di Giovanni, G P; Dionisi, C; Di Ruzza, B; Dittmann, J R; D'Onofrio, M; Donati, S; Dong, P; Donini, J; Dorigo, T; Dube, S; Efron, J; Erbacher, R; Errede, D; Errede, S; Eusebi, R; Fang, H C; Farrington, S; Fedorko, W T; Feild, R G; Feindt, M; Fernandez, J P; Ferrazza, C; Field, R; Flanagan, G; Forrest, R; Forrester, S; Franklin, M; Freeman, J C; Furic, I; Gallinaro, M; Galyardt, J; Garberson, F; Garcia, J E; Garfinkel, A F; Gerberich, H; Gerdes, D; Giagu, S; Giakoumopolou, V; Giannetti, P; Gibson, K; Gimmell, J L; Ginsburg, C M; Giokaris, N; Giordani, M; Giromini, P; Giunta, M; Glagolev, V; Glenzinski, D; Gold, M; Goldschmidt, N; Golossanov, A; Gomez, G; Gomez-Ceballos, G; Goncharov, M; González, O; Gorelov, I; Goshaw, A T; Goulianos, K; Gresele, A; Grinstein, S; Grosso-Pilcher, C; Grundler, U; Guimaraes da Costa, J; Gunay-Unalan, Z; Haber, C; Hahn, K; Hahn, S R; Halkiadakis, E; Hamilton, A; Han, B-Y; Han, J Y; Handler, R; Happacher, F; Hara, K; Hare, D; Hare, M; Harper, S; Harr, R F; Harris, R M; Hartz, M; Hatakeyama, K; Hauser, J; Hays, C; Heck, M; Heijboer, A; Heinemann, B; Heinrich, J; Henderson, C; Herndon, M; Heuser, J; Hewamanage, S; Hidas, D; Hill, C S; Hirschbuehl, D; Hocker, A; Hou, S; Houlden, M; Hsu, S-C; Huffman, B T; Hughes, R E; Husemann, U; Huston, J; Incandela, J; Introzzi, G; Iori, M; Ivanov, A; Iyutin, B; James, E; Jayatilaka, B; Jeans, D; Jeon, E J; Jindariani, S; Johnson, W; Jones, M; Joo, K K; Jun, S Y; Jung, J E; Junk, T R; Kamon, T; Kar, D; Karchin, P E; Kato, Y; Kephart, R; Kerzel, U; Khotilovich, V; Kilminster, B; Kim, D H; Kim, H S; Kim, J E; Kim, M J; Kim, S B; Kim, S H; Kim, Y K; Kimura, N; Kirsch, L; Klimenko, S; Klute, M; Knuteson, B; Ko, B R; Koay, S A; Kondo, K; Kong, D J; Konigsberg, J; Korytov, A; Kotwal, A V; Kraus, J; Kreps, M; Kroll, J; Krumnack, N; Kruse, M; Krutelyov, V; Kubo, T; Kuhlmann, S E; Kuhr, T; Kulkarni, N P; Kusakabe, Y; Kwang, S; Laasanen, A T; Lai, S; Lami, S; Lammel, S; Lancaster, M; Lander, R L; Lannon, K; Lath, A; Latino, G; Lazzizzera, I; Lecompte, T; Lee, J; Lee, J; Lee, Y J; Lee, S W; Lefèvre, R; Leonardo, N; Leone, S; Levy, S; Lewis, J D; Lin, C; Lin, C S; Linacre, J; Lindgren, M; Lipeles, E; Lister, A; Litvintsev, D O; Liu, T; Lockyer, N S; Loginov, A; Loreti, M; Lovas, L; Lu, R-S; Lucchesi, D; Lueck, J; Luci, C; Lujan, P; Lukens, P; Lungu, G; Lyons, L; Lys, J; Lysak, R; Lytken, E; Mack, P; Macqueen, D; Madrak, R; Maeshima, K; Makhoul, K; Maki, T; Maksimovic, P; Malde, S; Malik, S; Manca, G; Manousakis, A; Margaroli, F; Marino, C; Marino, C P; Martin, A; Martin, M; Martin, V; Martínez, M; Martínez-Ballarín, R; Maruyama, T; Mastrandrea, P; Masubuchi, T; Mattson, M E; Mazzanti, P; McFarland, K S; McIntyre, P; McNulty, R; Mehta, A; Mehtala, P; Menzemer, S; Menzione, A; Merkel, P; Mesropian, C; Messina, A; Miao, T; Miladinovic, N; Miles, J; Miller, R; Mills, C; Milnik, M; Mitra, A; Mitselmakher, G; Miyake, H; Moed, S; Moggi, N; Moon, C S; Moore, R; Morello, M; Movilla Fernandez, P; Mülmenstädt, J; Mukherjee, A; Muller, Th; Mumford, R; Murat, P; Mussini, M; Nachtman, J; Nagai, Y; Nagano, A; Naganoma, J; Nakamura, K; Nakano, I; Napier, A; Necula, V; Neu, C; Neubauer, M S; Nielsen, J; Nodulman, L; Norman, M; Norniella, O; Nurse, E; Oh, S H; Oh, Y D; Oksuzian, I; Okusawa, T; Oldeman, R; Orava, R; Osterberg, K; Pagan Griso, S; Pagliarone, C; Palencia, E; Papadimitriou, V; Papaikonomou, A; Paramonov, A A; Parks, B; Pashapour, S; Patrick, J; Pauletta, G; Paulini, M; Paus, C; Pellett, D E; Penzo, A; Phillips, T J; Piacentino, G; Piedra, J; Pinera, L; Pitts, K; Plager, C; Pondrom, L; Portell, X; Poukhov, O; Pounder, N; Prakoshyn, F; Pronko, A; Proudfoot, J; Ptohos, F; Punzi, G; Pursley, J; Rademacker, J; Rahaman, A; Ramakrishnan, V; Ranjan, N; Redondo, I; Reisert, B; Rekovic, V; Renton, P; Rescigno, M; Richter, S; Rimondi, F; Ristori, L; Robson, A; Rodrigo, T; Rogers, E; Rolli, S; Roser, R; Rossi, M; Rossin, R; Roy, P; Ruiz, A; Russ, J; Rusu, V; Saarikko, H; Safonov, A; Sakumoto, W K; Salamanna, G; Saltó, O; Santi, L; Sarkar, S; Sartori, L; Sato, K; Savoy-Navarro, A; Scheidle, T; Schlabach, P; Schmidt, E E; Schmidt, M A; Schmidt, M P; Schmitt, M; Schwarz, T; Scodellaro, L; Scott, A L; Scribano, A; Scuri, F; Sedov, A; Seidel, S; Seiya, Y; Semenov, A; Sexton-Kennedy, L; Sfyria, A; Shalhout, S Z; Shapiro, M D; Shears, T; Shepard, P F; Sherman, D; Shimojima, M; Shochet, M; Shon, Y; Shreyber, I; Sidoti, A; Sinervo, P; Sisakyan, A; Slaughter, A J; Slaunwhite, J; Sliwa, K; Smith, J R; Snider, F D; Snihur, R; Soderberg, M; Soha, A; Somalwar, S; Sorin, V; Spalding, J; Spinella, F; Spreitzer, T; Squillacioti, P; Stanitzki, M; St Denis, R; Stelzer, B; Stelzer-Chilton, O; Stentz, D; Strologas, J; Stuart, D; Suh, J S; Sukhanov, A; Sun, H; Suslov, I; Suzuki, T; Taffard, A; Takashima, R; Takeuchi, Y; Tanaka, R; Tecchio, M; Teng, P K; Terashi, K; Thom, J; Thompson, A S; Thompson, G A; Thomson, E; Tipton, P; Tiwari, V; Tkaczyk, S; Toback, D; Tokar, S; Tollefson, K; Tomura, T; Tonelli, D; Torre, S; Torretta, D; Tourneur, S; Trischuk, W; Tu, Y; Turini, N; Ukegawa, F; Uozumi, S; Vallecorsa, S; van Remortel, N; Varganov, A; Vataga, E; Vázquez, F; Velev, G; Vellidis, C; Veszpremi, V; Vidal, M; Vidal, R; Vila, I; Vilar, R; Vine, T; Vogel, M; Volobouev, I; Volpi, G; Würthwein, F; Wagner, P; Wagner, R G; Wagner, R L; Wagner-Kuhr, J; Wagner, W; Wakisaka, T; Wallny, R; Wang, S M; Warburton, A; Waters, D; Weinberger, M; Wester, W C; Whitehouse, B; Whiteson, D; Wicklund, A B; Wicklund, E; Williams, G; Williams, H H; Wilson, P; Winer, B L; Wittich, P; Wolbers, S; Wolfe, C; Wright, T; Wu, X; Wynne, S M; Yagil, A; Yamamoto, K; Yamaoka, J; Yamashita, T; Yang, C; Yang, U K; Yang, Y C; Yao, W M; Yeh, G P; Yoh, J; Yorita, K; Yoshida, T; Yu, G B; Yu, I; Yu, S S; Yun, J C; Zanello, L; Zanetti, A; Zaw, I; Zhang, X; Zheng, Y; Zucchelli, S

2008-03-14

Inclusive jet cross sections in Z/gamma* events, with Z/gamma* decaying into an electron-positron pair, are measured as a function of jet transverse momentum and jet multiplicity in pp[over ] collisions at square root s = 1.96 TeV with the upgraded Collider Detector at Fermilab in run II, based on an integrated luminosity of 1.7 fb(-1). The measurements cover the rapidity region |y(jet)|<2.1 and the transverse momentum range p(T)(jet)>30 GeV/c. Next-to-leading order perturbative QCD predictions are in good agreement with the measured cross sections.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schiller, A; Voinov, A; Algin, E

Two-step-cascade spectra in {sup 172}Yb have been measured after thermal neutron capture. they are compared to calculations based on experimental values of the level density and radiative strength function (RSF) obtained from the {sup 173}Yb(3{sup 3}He,{alpha}{gamma}){sup 172}Yb reaction. The multipolarity of a 6.5(15) {mu}{sub N}{sup 2} resonance at E{sub {gamma}} = 3.3(1) MeV in the RSF is determined to be M1 by this comparison.

Reconstructing the Gamma-Ray Photon Optical Depth of the Universe To Z Approx. 4 from Multiwavelength Galaxy Survey Data

NASA Technical Reports Server (NTRS)

Helgason, Kari; Kashlinsky, Alexander

2012-01-01

Reconstructing the Gamma-Ray Photon Optical Depth of the Universe To Z Approx. 4fFrom Multiwavelength Galaxy Survey Data We reconstruct the gamma-ray opacity of the universe out to z approx. < 3–4 using an extensive library of 342 observed galaxy luminosity function (LF) surveys extending to high redshifts .We cover the whole range from UV to mid-IR (0.15–25 micron ) providing for the first time a robust empirical calculation of the gamma gamma optical depth out to several TeV. Here, we use the same database as Helgason et al. where the extragalactic background light was reconstructed from LFs out to 4.5 micron and was shown to recover observed galaxy counts to high accuracy. We extend our earlier library Of LFs to 25micron such that it covers the energy range of pair production with gamma -rays (1) in the entire Fermi/LAT energy range, and (2) at higher TeV energies probed by ground-based Cherenkov telescopes. In the absence of significant contributions to the cosmic diffuse background from unknown populations, such as the putative Population III era sources, the universe appears to be largely transparent to gamma-rays at all Fermi/LAT energies out to z approx.. 2 whereas it becomes opaque to TeV photons already at z approx. < 0.2 and reaching tau approx 10 at z = 1. Comparing with the currently available Fermi/LAT gamma-ray burst and blazar data shows that there is room for significant emissions originating in the first stars era.

The gamma-aminobutyric acid shunt contributes to closing the tricarboxylic acid cycle in Synechocystis sp PCC 6803

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xiong, W; Brune, D; Vermaas, WFJ

2014-07-16

A traditional 2-oxoglutarate dehydrogenase complex is missing in the cyanobacterial tricarboxylic acid cycle. To determine pathways that convert 2-oxoglutarate into succinate in the cyanobacterium Synechocystis sp. PCC 6803, a series of mutant strains, Delta sll1981, Delta slr0370, Delta slr1022 and combinations thereof, deficient in 2-oxoglutarate decarboxylase (Sll1981), succinate semialdehyde dehydrogenase (Slr0370), and/or in gamma-aminobutyrate metabolism (Slr1022) were constructed. Like in Pseudomonas aeruginosa, N-acetylornithine aminotransferase, encoded by slr1022, was shown to also function as gamma-aminobutyrate aminotransferase, catalysing gamma-aminobutyrate conversion to succinic semialdehyde. As succinic semialdehyde dehydrogenase converts succinic semialdehyde to succinate, an intact gamma-aminobutyrate shunt is present in Synechocystis. The Deltamore » sll1981 strain, lacking 2-oxoglutarate decarboxylase, exhibited a succinate level that was 60% of that in wild type. However, the succinate level in the Delta slr1022 and Delta slr0370 strains and the Delta sll1981/Delta slr1022 and Delta sll1981/Delta slr0370 double mutants was reduced to 20-40% of that in wild type, suggesting that the gamma-aminobutyrate shunt has a larger impact on metabolite flux to succinate than the pathway via 2-oxoglutarate decarboxylase. C-13-stable isotope analysis indicated that the gamma-aminobutyrate shunt catalysed conversion of glutamate to succinate. Independent of the 2-oxoglutarate decarboxylase bypass, the gamma-aminobutyrate shunt is a major contributor to flux from 2-oxoglutarate and glutamate to succinate in Synechocystis sp. PCC 6803.« less

Equilibrium fluid interface behavior under low- and zero-gravity conditions

NASA Technical Reports Server (NTRS)

Concus, Paul; Finn, Robert

1994-01-01

We describe here some of our recent mathematical work, which forms a basis for the Interface Configuration Experiment scheduled for USML-2. The work relates to the design of apparatus that exploits microgravity conditions for accurate determination of contact angle. The underlying motivation for the procedures rests on a discontinuous dependence of the capillary free surface interface S on the contact angle gamma, in a cylindrical capillary tube whose section (base) omega contains a protruding corner with opening angle 2 alpha. Specifically, in a gravity-free environment, omega can be chosen so that, for all sufficiently large fluid volume, the height of S is uniquely determined as a (single-valued) function mu(x,y) entirely covering the base; the height mu is bounded over omega uniformly in gamma throughout the range absolute value of (gamma -(pion/2)) less than or equal to alpha, while for absolute value of (gamma - (pion/2)) greater than alpha fluid will necessarily move to the corner and uncover the base, rising to infinity (or falling to negative infinity) at the vertex, regardless of volume. We mention here only that procedures based on the phenomenon promise excellent accuracy when gamma is close pion/2 but may be subject to experimental error when gamma is close to zero (orpion), as the 'singular' part of the domain over which the fluid accumulates (or disappears) when a critical angle gamma theta is crossed then becomes very small and may be difficult to observe. We ignore the trivial case gamma is equal to pion/2 (planar free surface), to simplify the discussion.

Potential Protective Effects of Ursolic Acid against Gamma Irradiation-Induced Damage Are Mediated through the Modulation of Diverse Inflammatory Mediators

PubMed Central

Wang, Hong; Sim, Meng-Kwoon; Loke, Weng Keong; Chinnathambi, Arunachalam; Alharbi, Sulaiman Ali; Tang, Feng Ru; Sethi, Gautam

2017-01-01

This study was aimed to evaluate the possible protective effects of ursolic acid (UA) against gamma radiation induced damage both in vitro as well as in vivo. It was observed that the exposure to gamma radiation dose- and time-dependently caused a significant decrease in the cell viability, while the treatment of UA attenuated this cytotoxicity. The production of free radicals including reactive oxygen species (ROS) and NO increased significantly post-irradiation and further induced lipid peroxidation and oxidative DNA damage in cells. These deleterious effects could also be effectively blocked by UA treatment. In addition, UA also reversed gamma irradiation induced inflammatory responses, as indicated by the decreased production of TNF-α, IL-6, and IL-1β. NF-κB signaling pathway has been reported to be a key mediator involved in gamma radiation-induced cellular damage. Our results further demonstrated that gamma radiation dose- and time-dependently enhanced NF-κB DNA binding activity, which was significantly attenuated upon UA treatment. The post-irradiation increase in the expression of both phospho-p65, and phospho-IκBα was also blocked by UA. Moreover, the treatment of UA was found to significantly prolong overall survival in mice exposed to whole body gamma irradiation, and reduce the excessive inflammatory responses. Given its radioprotective efficacy as described here, UA as an antioxidant and NF-κB pathway blocker, may function as an important pharmacological agent in protecting against gamma irradiation-induced injury. PMID:28670276

EGRET Diffuse Gamma Ray Maps Between 30 MeV and 10 GeV

NASA Technical Reports Server (NTRS)

Cillis, A, N.; Hartman, R. C.

2004-01-01

This paper presents all-sky maps of diffuse gamma radiation in various energy ranges between 30 MeV and 10 GeV, based on data collected by the EGRET instrument on the Compton Gamma Ray Observatory. Although the maps can be used for a variety of applications. the immediate goal is the generation of diffuse gamma-ray maps which can be used as a diffuse background/foreground for point source analysis of the data to be obtained from new high-energy gamma-ray missions like GLAST and AGILE. To generate the diffuse gamma maps from the raw EGRET maps, the point sources in the Third EGRET Catalog were subtracted out using the appropriate point spread function for each energy range. After that, smoothing was performed to minimize the effects of photon statistical noise. A smoothing length of 1 deg vas used for the Galactic plane maps. For the all-sky maps, a procedure was used which resulted in a smoothing length roughly equivalent to 4 deg. The result of this work is 16 maps of different energy intervals for absolute value of b < or equal to 20 deg, and 32 all-sky maps, 16 in equatorial coordinates (J2000) and 16 in Galactic coordinates.

EGRET Diffuse Gamma Ray Maps Between 30 MeV and 10 GeV

NASA Technical Reports Server (NTRS)

Cillis, A. N.; Hartman, R. C.

2004-01-01

This paper presents all-sky maps of diffuse gamma radiation in various energy ranges between 30 MeV and 10 GeV, based on data collected by the EGRET instrument on the Compton Gamma Ray Observatory. Although the maps can be used for a variety of applications, the immediate goal is the generation of diffuse gamma-ray maps which can be used as a diffuse background/foreground for point source analysis of the data to be obtained from new high-energy gamma-ray missions like GLAST and AGILE. To generate the diffuse gamma maps from the raw EGRET maps, the point sources in the Third EGRET Catalog were subtracted out using the appropriate point spread function for each energy range. After that, smoothing was performed to minimize the effects of photon statistical noise. A smoothing length of 1deg was used for the Galactic plane maps. For the all-sky maps, a procedure was used which resulted in a smoothing length roughly equivalent to 4deg. The result of this work is 16 maps of different energy intervals for [b]less than or equal to 20deg, and 32 all-sky maps, 16 in equatorial coordinates (J2000) and 16 in Galactic coordinates.

GABAB-mediated rescue of altered excitatory-inhibitory balance, gamma synchrony and behavioral deficits following constitutive NMDAR-hypofunction.

PubMed

Gandal, M J; Sisti, J; Klook, K; Ortinski, P I; Leitman, V; Liang, Y; Thieu, T; Anderson, R; Pierce, R C; Jonak, G; Gur, R E; Carlson, G; Siegel, S J

2012-07-17

Reduced N-methyl-D-aspartate-receptor (NMDAR) signaling has been associated with schizophrenia, autism and intellectual disability. NMDAR-hypofunction is thought to contribute to social, cognitive and gamma (30-80 Hz) oscillatory abnormalities, phenotypes common to these disorders. However, circuit-level mechanisms underlying such deficits remain unclear. This study investigated the relationship between gamma synchrony, excitatory-inhibitory (E/I) signaling, and behavioral phenotypes in NMDA-NR1(neo-/-) mice, which have constitutively reduced expression of the obligate NR1 subunit to model disrupted developmental NMDAR function. Constitutive NMDAR-hypofunction caused a loss of E/I balance, with an increase in intrinsic pyramidal cell excitability and a selective disruption of parvalbumin-expressing interneurons. Disrupted E/I coupling was associated with deficits in auditory-evoked gamma signal-to-noise ratio (SNR). Gamma-band abnormalities predicted deficits in spatial working memory and social preference, linking cellular changes in E/I signaling to target behaviors. The GABA(B)-receptor agonist baclofen improved E/I balance, gamma-SNR and broadly reversed behavioral deficits. These data demonstrate a clinically relevant, highly translatable neural-activity-based biomarker for preclinical screening and therapeutic development across a broad range of disorders that share common endophenotypes and disrupted NMDA-receptor signaling.

Early cognitive and language skills are linked to resting frontal gamma power across the first 3 years.

PubMed

Benasich, April A; Gou, Zhenkun; Choudhury, Naseem; Harris, Kenneth D

2008-12-22

High-frequency cortical activity in humans and animals has been linked to a wide variety of higher cognitive processes. This research suggests that specific changes in neuronal synchrony occur during cognitive processing, distinguished by emergence of fast oscillations in the gamma frequency range. To determine whether the development of high-frequency brain oscillations can be related to the development of cognitive abilities, we studied the power spectra of resting EEG in children 16, 24 and 36 months of age. Individual differences in the distribution of frontal gamma power during rest were highly correlated with concurrent language and cognitive skills at all ages. Gamma power was also associated with attention measures; children who were observed as having better inhibitory control and more mature attention shifting abilities had higher gamma power density functions. We included a group of children with a family history of language impairment (FH+) and thus at higher risk for language disorders. FH+ children, as a group, showed consistently lower gamma over frontal regions than the well-matched FH- controls with no such family history (FH-). We suggest that the emergence of high-frequency neural synchrony may be critical for cognitive and linguistic development, and that children at risk for language impairments may lag in this process.

The gamma delta T cell repertoire in Graves' disease and multinodular goitre.

PubMed Central

McIntosh, R S; Tandon, N; Pickerill, A P; Davies, R; Barnett, D; Weetman, A P

1993-01-01

gamma delta T cells are a subset of T cells with unknown function, and restriction of the gamma delta T cell receptor (TCR) repertoire has been described in rheumatoid arthritis and multiple sclerosis. Elevated numbers of gamma delta T cells have been reported in the peripheral blood and thyroids of patients with Graves' disease. We have carried out flow cytometric analysis on peripheral blood mononuclear cells (PBMC) and intrathyroidal lymphocytes (ITL) from 12 patients with Graves' disease and nine patients with multinodular goitre (MNG), a thyroid disease of unknown etiology. There was no significant difference between the proportion of gamma delta T cells in the PBMC of Graves' and MNG patients, nor between the PBMC and ITL populations in either patient group. We have also carried out polymerase chain reaction amplification on RNA prepared from matched PBMC, ITL and the activated (CD25+) subset of ITL using six TCR V delta-family specific primers. Although there were differences in the amounts of each V delta transcript amplified from PBMC and ITL, there was no difference between the two patient groups. No consistent differences were therefore found between the gamma delta T cell populations in Graves' and MNG patients, arguing against the direct involvement of this T cell subset in the pathogenesis of Graves' disease. Images Fig. 1 PMID:8252809

A program to generate simulated radioxenon beta–gamma data for concentration verification and validation and training exercises

DOE Office of Scientific and Technical Information (OSTI.GOV)

McIntyre, Justin I.; Schrom, Brian T.; Cooper, Matthew W.

2016-03-08

Abstract Several hundred simulated radioxenon beta-gamma data files were developed to assist in evaluating the performance and results from radioxenon concentration calculation analysis at the International Data Center (IDC) and other National Data Centers (NDC). PNNL developed a Beta-Gamma Simulator (BGSim) that incorporated GEANT-modeled data sets from radioxenon decay chains, as well as functionality to use nuclear detector-acquired data sets to create new beta-gamma spectra with varying amounts of background, 133Xe, 131mXe, 133mXe, 135Xe, and 222Rn and its decay products. The program has been implemented on a web-based applications platform and allows the user to create very specific data setsmore » that incorporate most of the operational parameters for the current beta-gamma systems deployed in the International Monitoring System (IMS) and the On-site Inspection (OSI) equipment. After an initial beta-gamma simulations program was developed, additional uses began to be identified for the program output: training sets of two-dimensional spectra for data analysts at the IDC and other NDC, spectra for exercises such as the Integrated Field Exercise 2014 (IFE14) held in Jordan at the Dead Sea, and testing new analysis methods and algorithms« less

Molecular Static Third-Order Polarizabilities of Carbon-Cage Fullerene and Their Correlation with Three Geometric Properties: Symmetry, Aromaticity, and Size

NASA Technical Reports Server (NTRS)

Moore, C. E.; Cardelino, B. H.; Frazier, D. O.; Niles, J.; Wang, X.-Q.

1998-01-01

The static third-order polarizabilities (gamma) of C60, C70, five isomers of C78 and two isomers of C84 were analyzed in terms of three properties, from a geometric point of view: symmetry, aromaticity and size. The polarizability values were based on the finite field approximation using a semiempirical Hamiltonian (AM1) and applied to molecular structures obtained from density functional theory calculations. Symmetry was characterized by the molecular group order. The selection of 6-member rings as aromatic was determined from an analysis of bond lengths. Maximum interatomic distance and surface area were the parameters considered with respect to size. Based on triple linear regression analysis, it was found that the static linear polarizability (alpha) and gamma in these molecules respond differently to geometrical properties: alpha depends almost exclusively on surface area while gamma is affected by a combination of number of aromatic rings, length and group order, in decreasing importance. In the case of alpha, valence electron contributions provide the same information as all-electron estimates. For gamma, the best correlation coefficients are obtained when all-electron estimates are used and when the dependent parameter is ln(gamma) instead of gamma.

Using the Human Eye to Characterize Displays

NASA Technical Reports Server (NTRS)

Gille, Jennifer; Larimer, James

2001-01-01

Monitor characterization has taken on new importance for non-professional users, who are not usually equipped to make photometric measurements. Our purpose was to examine some of the visual judgments used in characterization schemes that have been proposed for web users. We studied adjusting brightness to set the black level, banding effects due to digitization, and gamma estimation in the light and in the dark, and a color-matching task in the light, on a desktop CRT and a laptop LCD. Observers demonstrated the sensitivity of the visual system for comparative judgments in black-level adjustment, banding visibility, and gamma estimation. The results of the color-matching task were ambiguous. In the brightness adjustment task, the action of the adjustment was not as presumed; however, perceptual judgments were as expected under the actual conditions. When the gamma estimates of observers were compared to photometric measurements, problems with the definition of gamma were identified. Information about absolute light levels that would be important for characterizing a display, given the shortcomings of gamma in measuring apparent contrast, are not measurable by eye alone. The LCD was not studied as extensively as the CRT because of viewing-angle problems, and its transfer function did not follow a power law, rendering gamma estimation meaningless.

Fermi-LAT Detection of Gravitational Lens Delayed Gamma-Ray Flares from Blazar B0218+357

NASA Technical Reports Server (NTRS)

Cheung, C. C.; Larsson, S.; Scargle, J. D.; Amin, M. A.; Blandford, R. D.; Bulmash, D.; Chiang, J.; Ciprini, S.; Corbet, R. D. H.; Falco, E. E.;

Fast oscillations in cortical-striatal networks switch frequency following rewarding events and stimulant drugs.

PubMed

Berke, J D

2009-09-01

Oscillations may organize communication between components of large-scale brain networks. Although gamma-band oscillations have been repeatedly observed in cortical-basal ganglia circuits, their functional roles are not yet clear. Here I show that, in behaving rats, distinct frequencies of ventral striatal local field potential oscillations show coherence with different cortical inputs. The approximately 50 Hz gamma oscillations that normally predominate in awake ventral striatum are coherent with piriform cortex, whereas approximately 80-100 Hz high-gamma oscillations are coherent with frontal cortex. Within striatum, entrainment to gamma rhythms is selective to fast-spiking interneurons, with distinct fast-spiking interneuron populations entrained to different gamma frequencies. Administration of the psychomotor stimulant amphetamine or the dopamine agonist apomorphine causes a prolonged decrease in approximately 50 Hz power and increase in approximately 80-100 Hz power. The same frequency switch is observed for shorter epochs spontaneously in awake, undrugged animals and is consistently provoked for < 1 s following reward receipt. Individual striatal neurons can participate in these brief high-gamma bursts with, or without, substantial changes in firing rate. Switching between discrete oscillatory states may allow different modes of information processing during decision-making and reinforcement-based learning, and may also be an important systems-level process by which stimulant drugs affect cognition and behavior.

First limits on the very-high energy gamma-ray afterglow emission of a fast radio burst. H.E.S.S. observations of FRB 150418

NASA Astrophysics Data System (ADS)

H.E.S.S. Collaboration; Abdalla, H.; Abramowski, A.; Aharonian, F.; Ait Benkhali, F.; Akhperjanian, A. G.; Andersson, T.; Angüner, E. O.; Arakawa, M.; Arrieta, M.; Aubert, P.; Backes, M.; Balzer, A.; Barnard, M.; Becherini, Y.; Becker Tjus, J.; Berge, D.; Bernhard, S.; Bernlöhr, K.; Blackwell, R.; Böttcher, M.; Boisson, C.; Bolmont, J.; Bordas, P.; Bregeon, J.; Brun, F.; Brun, P.; Bryan, M.; Büchele, M.; Bulik, T.; Capasso, M.; Carr, J.; Casanova, S.; Cerruti, M.; Chakraborty, N.; Chalme-Calvet, R.; Chaves, R. C. G.; Chen, A.; Chevalier, J.; Chrétien, M.; Coffaro, M.; Colafrancesco, S.; Cologna, G.; Condon, B.; Conrad, J.; Cui, Y.; Davids, I. D.; Decock, J.; Degrange, B.; Deil, C.; Devin, J.; Dewilt, P.; Dirson, L.; Djannati-Ataï, A.; Domainko, W.; Donath, A.; Drury, L. O.'c.; Dutson, K.; Dyks, J.; Edwards, T.; Egberts, K.; Eger, P.; Ernenwein, J.-P.; Eschbach, S.; Farnier, C.; Fegan, S.; Fernandes, M. V.; Fiasson, A.; Fontaine, G.; Förster, A.; Funk, S.; Füßling, M.; Gabici, S.; Gajdus, M.; Gallant, Y. A.; Garrigoux, T.; Giavitto, G.; Giebels, B.; Glicenstein, J. F.; Gottschall, D.; Goyal, A.; Grondin, M.-H.; Hahn, J.; Haupt, M.; Hawkes, J.; Heinzelmann, G.; Henri, G.; Hermann, G.; Hervet, O.; Hinton, J. A.; Hofmann, W.; Hoischen, C.; Holler, M.; Horns, D.; Ivascenko, A.; Iwasaki, H.; Jacholkowska, A.; Jamrozy, M.; Janiak, M.; Jankowsky, D.; Jankowsky, F.; Jingo, M.; Jogler, T.; Jouvin, L.; Jung-Richardt, I.; Kastendieck, M. A.; Katarzyński, K.; Katsuragawa, M.; Katz, U.; Kerszberg, D.; Khangulyan, D.; Khélifi, B.; Kieffer, M.; King, J.; Klepser, S.; Klochkov, D.; Kluźniak, W.; Kolitzus, D.; Komin, Nu.; Kosack, K.; Krakau, S.; Kraus, M.; Krüger, P. P.; Laffon, H.; Lamanna, G.; Lau, J.; Lees, J.-P.; Lefaucheur, J.; Lefranc, V.; Lemière, A.; Lemoine-Goumard, M.; Lenain, J.-P.; Leser, E.; Lohse, T.; Lorentz, M.; Liu, R.; López-Coto, R.; Lypova, I.; Marandon, V.; Marcowith, A.; Mariaud, C.; Marx, R.; Maurin, G.; Maxted, N.; Mayer, M.; Meintjes, P. J.; Meyer, M.; Mitchell, A. M. W.; Moderski, R.; Mohamed, M.; Mohrmann, L.; Morå, K.; Moulin, E.; Murach, T.; Nakashima, S.; de Naurois, M.; Niederwanger, F.; Niemiec, J.; Oakes, L.; O'Brien, P.; Odaka, H.; Öttl, S.; Ohm, S.; Ostrowski, M.; Oya, I.; Padovani, M.; Panter, M.; Parsons, R. D.; Pekeur, N. W.; Pelletier, G.; Perennes, C.; Petrucci, P.-O.; Peyaud, B.; Piel, Q.; Pita, S.; Poon, H.; Prokhorov, D.; Prokoph, H.; Pühlhofer, G.; Punch, M.; Quirrenbach, A.; Raab, S.; Reimer, A.; Reimer, O.; Renaud, M.; de Los Reyes, R.; Richter, S.; Rieger, F.; Romoli, C.; Rowell, G.; Rudak, B.; Rulten, C. B.; Sahakian, V.; Saito, S.; Salek, D.; Sanchez, D. A.; Santangelo, A.; Sasaki, M.; Schlickeiser, R.; Schüssler, F.; Schulz, A.; Schwanke, U.; Schwemmer, S.; Seglar-Arroyo, M.; Settimo, M.; Seyffert, A. S.; Shafi, N.; Shilon, I.; Simoni, R.; Sol, H.; Spanier, F.; Spengler, G.; Spies, F.; Stawarz, Ł.; Steenkamp, R.; Stegmann, C.; Stycz, K.; Sushch, I.; Takahashi, T.; Tavernet, J.-P.; Tavernier, T.; Taylor, A. M.; Terrier, R.; Tibaldo, L.; Tiziani, D.; Tluczykont, M.; Trichard, C.; Tsuji, N.; Tuffs, R.; Uchiyama, Y.; van der Walt, D. J.; van Eldik, C.; van Rensburg, C.; van Soelen, B.; Vasileiadis, G.; Veh, J.; Venter, C.; Viana, A.; Vincent, P.; Vink, J.; Voisin, F.; Völk, H. J.; Vuillaume, T.; Wadiasingh, Z.; Wagner, S. J.; Wagner, P.; Wagner, R. M.; White, R.; Wierzcholska, A.; Willmann, P.; Wörnlein, A.; Wouters, D.; Yang, R.; Zabalza, V.; Zaborov, D.; Zacharias, M.; Zanin, R.; Zdziarski, A. A.; Zech, A.; Zefi, F.; Ziegler, A.; Żywucka, N.; Superb Collaboration; Jankowski, F.; Keane, E. F.; Petroff, E.

2017-01-01

Aims: Following the detection of the fast radio burst FRB150418 by the SUPERB project at the Parkes radio telescope, we aim to search for very-high energy gamma-ray afterglow emission. Methods: Follow-up observations in the very-high energy gamma-ray domain were obtained with the H.E.S.S. imaging atmospheric Cherenkov telescope system within 14.5 h of the radio burst. Results: The obtained 1.4 h of gamma-ray observations are presented and discussed. At the 99% C.L. we obtained an integral upper limit on the gamma-ray flux of Φγ(E > 350 GeV) < 1.33 × 10-8 m-2 s-1. Differential flux upper limits as function of the photon energy were derived and used to constrain the intrinsic high-energy afterglow emission of FRB 150418. Conclusions: No hints for high-energy afterglow emission of FRB 150418 were found. Taking absorption on the extragalactic background light into account and assuming a distance of z = 0.492 based on radio and optical counterpart studies and consistent with the FRB dispersion, we constrain the gamma-ray luminosity at 1 TeV to L < 5.1 × 1047 erg/s at 99% C.L.

An Estimation of the Gamma-Ray Burst Afterglow Apparent Optical Brightness Distribution Function

NASA Astrophysics Data System (ADS)

Akerlof, Carl W.; Swan, Heather F.

2007-12-01

By using recent publicly available observational data obtained in conjunction with the NASA Swift gamma-ray burst (GRB) mission and a novel data analysis technique, we have been able to make some rough estimates of the GRB afterglow apparent optical brightness distribution function. The results suggest that 71% of all burst afterglows have optical magnitudes with mR<22.1 at 1000 s after the burst onset, the dimmest detected object in the data sample. There is a strong indication that the apparent optical magnitude distribution function peaks at mR~19.5. Such estimates may prove useful in guiding future plans to improve GRB counterpart observation programs. The employed numerical techniques might find application in a variety of other data analysis problems in which the intrinsic distributions must be inferred from a heterogeneous sample.

Supplementation with mixed tocopherols increases serum and blood cell gamma-tocopherol but does not alter biomarkers of platelet activation in subjects with type 2 diabetes.

PubMed

Clarke, Michael W; Ward, Natalie C; Wu, Jason H Y; Hodgson, Jonathan M; Puddey, Ian B; Croft, Kevin D

2006-01-01

Some studies have shown potential benefit of vitamin E on platelet function, but several clinical trials failed to show improved cardiovascular outcome with alpha-tocopherol supplementation. Gamma-tocopherol, a major dietary form of vitamin E, may have protective properties different from those of alpha-tocopherol. We compared the effects of supplementation with alpha-tocopherol (500 mg) and a gamma-tocopherol-rich compound (500 mg, containing 60% gamma-tocopherol) on serum and cellular tocopherol concentrations, urinary tocopherol metabolite excretion, and in vivo platelet activation in subjects with type 2 diabetes. Fifty-eight subjects were randomly assigned to receive either 500 mg alpha-tocopherol/d, 500 mg mixed tocopherols/d, or matching placebo. Serum, erythrocyte, and platelet tocopherol and urinary metabolite concentrations were measured at baseline and after the 6-wk intervention. Soluble CD40 ligand, urinary 11-dehydro-thromboxane B2, serum thromboxane B2, soluble P-selectin, and von Willebrand factor were measured as biomarkers of in vivo platelet activation. Serum alpha-tocopherol increased with both tocopherol treatments. Serum and cellular gamma-tocopherol increased 4-fold (P < 0.001) in the mixed tocopherol group, whereas red blood cell gamma-tocopherol decreased significantly after alpha-tocopherol supplementation. Excretion of alpha-carboxyethyl-hydroxychroman increased significantly after supplementation with alpha-tocopherol and mixed tocopherols. Excretion of gamma-carboxyethyl-hydroxychroman increased significantly after supplementation with mixed tocopherols and after that with alpha-tocopherol, which may reflect the displacement of gamma-tocopherol by alpha-tocopherol due to incorporation of the latter into lipoproteins in the liver. Neither treatment had any significant effect on markers of platelet activation. Supplementation with alpha-tocopherol decreased red blood cell gamma-tocopherol, whereas mixed tocopherols increased both serum alpha-tocopherol and serum and cellular gamma-tocopherol. Changes in serum tocopherol closely reflect changes in cellular concentrations of tocopherols after supplementation.

Phenotypic consequences of deletion of the {gamma}{sub 3}, {alpha}{sub 5}, or {beta}{sub 3} subunit of the type A {gamma}-aminobutyric acid receptor in mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Culia, C.T.; Stubbs, L.J.; Montgomery, C.S.

1994-03-29

Three genes (Gabrg3, Gabra5, and Gabrb3) encoding the {gamma}{sub 3}, {alpha}{sub 5}, and {beta}{sub 3} subunits of the type A {gamma}-aminobutyric acid receptor, respectively, are known to map near the pink-eyed dilution (p) locus in mouse chromosome 7. This region shares homology with a segment of human chromosome 15 that is implicated in Angelman syndrome, an inherited neurobehavioral disorder. By mapping Gabrg3-Gabra5-Gabrb3-telomere. Like Gabrb3, neither the Gabra5 nor Gabrg3 gene is functionally imprinted in adult mouse brain. Mice deleted for all three subunits die at birth with a cleft palate, although there are rare survivors ({approximately} 5%) that do notmore » have a cleft palate but do exhibit a neurological abnormality characterized by tremor, jerky gait, and runtiness. The authors have previously suggested that deficiency of the {beta}{sub 3} subunit may be responsible for the clefting defect. Most notably, however, in this report they describe mice carrying two overlapping, complementing p deletions that fail to express the {gamma}{sub 3} transcript, as well as mice from another line that express neither the {gamma}{sub 3} nor {alpha}{sub 5} transcripts. Surprisingly, mice from both of these lines are phenotypically normal and do not exhibit any of the neurological symptoms characteristic of the rare survivors that are deleted for all three ({gamma}{sub 3}, {alpha}{sub 5}, and {beta}{sub 3}) subunits. These mice therefore provide a whole-organism type A {gamma}-aminobutyric-acid receptor background that is devoid of any receptor subtypes that normally contain the {gamma}{sub 3} and/or {alpha}{sub 5} subunits. The absence of an overt neurological phenotype in mice lacking the {gamma}{sub 3} and/or {alpha}{sub 5} subunits also suggests that mutations in these genes are unlikely to provide useful animal models for Angelman syndrome in humans.« less

Thalamocortical Dysrhythmia: A Theoretical Update in Tinnitus

PubMed Central

De Ridder, Dirk; Vanneste, Sven; Langguth, Berthold; Llinas, Rodolfo

2015-01-01

Tinnitus is the perception of a sound in the absence of a corresponding external sound source. Pathophysiologically it has been attributed to bottom-up deafferentation and/or top-down noise-cancelling deficit. Both mechanisms are proposed to alter auditory ­thalamocortical signal transmission, resulting in thalamocortical dysrhythmia (TCD). In deafferentation, TCD is characterized by a slowing down of resting state alpha to theta activity associated with an increase in surrounding gamma activity, resulting in persisting cross-frequency coupling between theta and gamma activity. Theta burst-firing increases network synchrony and recruitment, a mechanism, which might enable long-range synchrony, which in turn could represent a means for finding the missing thalamocortical information and for gaining access to consciousness. Theta oscillations could function as a carrier wave to integrate the tinnitus-related focal auditory gamma activity in a consciousness enabling network, as envisioned by the global workspace model. This model suggests that focal activity in the brain does not reach consciousness, except if the focal activity becomes functionally coupled to a consciousness enabling network, aka the global workspace. In limited deafferentation, the missing information can be retrieved from the auditory cortical neighborhood, decreasing surround inhibition, resulting in TCD. When the deafferentation is too wide in bandwidth, it is hypothesized that the missing information is retrieved from theta-mediated parahippocampal auditory memory. This suggests that based on the amount of deafferentation TCD might change to parahippocampocortical persisting and thus pathological theta–gamma rhythm. From a Bayesian point of view, in which the brain is conceived as a prediction machine that updates its memory-based predictions through sensory updating, tinnitus is the result of a prediction error between the predicted and sensed auditory input. The decrease in sensory updating is reflected by decreased alpha activity and the prediction error results in theta–gamma and beta–gamma coupling. Thus, TCD can be considered as an adaptive mechanism to retrieve missing auditory input in tinnitus. PMID:26106362

Human serum cholinesterase from liver pathological samples exhibit highly elevated aryl acylamidase activity.

PubMed

Boopathy, Rathanam; Rajesh, Ramanna Valmiki; Darvesh, Sultan; Layer, Paul G

2007-05-01

Although aspartate aminotransferase (AST) and gamma-glutamyltransferase (gamma GT) enzymes are widely used as markers for liver disorders, the ubiquitous enzyme butyrylcholinesterase (BChE), synthesized in liver is also used as marker in the assessment of liver pathophysiology. This BChE enzyme in addition to its esterase activity has yet another enzymatic function designated as aryl acylamidase (AAA) activity. It is determined in in vitro based on the hydrolysis of the synthetic substrate o-nitroacetanilide. In the present study, human serum cholinesterase (BChE) activity was studied with respect to its AAA activity on the BChE protein (AAA(BChE)) in patients with liver disorders. AST and gamma GT values were taken into account in this study as known markers for liver disorders. Blood samples were grouped into 3 based on esterase activity associated with BChE protein. They are normal, low, and very low BChE activity but with markedly increased AST and gamma GT levels. These samples were tested for their respective AAA function. Association of AAA with BChE from samples was proved using BChE monoclonal antibody precipitation experiment. The absolute levels of AAA were increased as BChE activity decreased while deviating from normal samples and such deviation was directly proportional to the severity of the liver disorder. Differences between these groups became prominent after determining the ratios of AAA(BChE) to BChE activities. Samples showing very high AAA(BChE) to BChE ratio were also showing high to very high gamma GT values. These findings establish AAA(BChE) as an independently regulated enzymatic activity on BChE especially in liver disorders. Moreover, since neither the low esterase activity of BChE by itself nor increased levels of AST/gamma GT are sufficient pathological indicators, this pilot study merits replication with large sample numbers.

[Induction of glutathione and activation of immune functions by low-dose, whole-body irradiation with gamma-rays].

PubMed

Kojima, Shuji

2006-10-01

We first examined the relation between the induction of glutathione and immune functions in mice after low-dose gamma-ray irradiation. Thereafter, inhibition of tumor growth by radiation was confirmed in Ehrlich solid tumor (EST)-bearing mice. The total glutathione level of the splenocytes transiently increased soon after irradiation and reached a maximum at around 4 h postirradiation. Thereafter, the level reverted to the 0 h value by 24 h postirradiation. A significantly high splenocyte proliferative response was also recognized 4 h postirradiation. Natural killer (NK) activity was also increased significantly in a similar manner. The time at which the response reached the maximum coincided well with that of maximum total glutathione levels of the splenocytes in the gamma-ray-irradiated mice. Reduced glutathione exogenously added to splenocytes obtained from normal mice enhanced the proliferative response and NK activity in a dose-dependent manner. The inhibitory effects of radiation on tumor growth was then examined in EST-bearing mice. Repeated low-dose irradiation (0.5 Gy, four times, before and within an early time after inoculation) significantly delayed the tumor growth. Finally, the effect of single low-dose (0.5 Gy), whole-body gamma-ray irradiation on immune balance was examined to elucidate the mechanism underlying the antitumor immunity. The percentage of B cells in blood lymphocytes was selectively decreased after radiation, concomitant with an increase in that of the helper T cell population. The IFN-gamma level in splenocyte culture prepared from EST-bearing mice was significantly increased 48 h after radiation, although the level of IL-4 was unchanged. IL-12 secretion from macrophages was also enhanced by radiation. These results suggest that low-dose gamma-rays induce Th1 polarization and enhance the activities of tumoricidal effector cells, leading to an inhibition of tumor growth.

ARES: automated response function code. Users manual. [HPGAM and LSQVM

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maung, T.; Reynolds, G.M.

This ARES user's manual provides detailed instructions for a general understanding of the Automated Response Function Code and gives step by step instructions for using the complete code package on a HP-1000 system. This code is designed to calculate response functions of NaI gamma-ray detectors, with cylindrical or rectangular geometries.

Study of genetic effects of high energy radiations with different ionizing capacities on extracellular phages.

PubMed

Bresler, S E; Kalinin, V L; Kopylova, Y U; Krivisky, A S; Rybchin, V N; Shelegedin, V N

1975-07-01

The inactivating and mutagenic action of high-energy radiations with different ionizing capacities (gamma-rays, protons, alpha-particles and accelerated ions of 12C and 20Ne) was studied by using coliphages lambda11 and SD as subjects. In particular the role of irradiation conditions (broth suspension, pure buffer, dry samples) and of the host functions recA, exrA and polA was investigated. The dose-response curve of induced mutagenesis was studied by measuring the yield of vir mutants in lambda11 and plaque mutants in SD. The following results were obtained. (1) The inactivation kinetics of phages under the action of gamma-rays and protons was first order to a survival of 10(-7). Heavy ions also showed exponential inactivation kinetics to a survival of 10(-4). At higher doses of 20Ne ion bombardment some deviation from one-hit kinetics was observed. For dry samples of phages the dimensions of targets for all types of radiation were approximately proportional to the molecular weights of phage DNA's. For densely ionizing radiation (heavy ions) the inactivating action was 3-5 times weaker than for gamma-rays and protons. (2) Mutagenesis was observed for all types of radiation, but heavy ions were 1-5-2 times less efficient than gamma-rays. For both phages studied the dose-response curve of mutagenesis was non-linear. The dependence on the dose was near to parabolic for lambda11. For SD a plateau or maximum of mutagenesis was observed for the relative number of mutants at a survival of about 10(-4). (3) Host-cell functions recA and exrA were practically indifferent for survival of gamma-irradiated phage lambda11, but indispensable for mutagenesis. Mutation recAI3 abolished induced vir mutations totally and exrA- reduced them significantly. The absence of the function polA had a considerable influence on phage survival, but no effect on vir mutation yield (if compared at the same survival level). (4) In conditions of indirect action of gamma-rays no vir mutations were induced. This is regarded as evidence that the single-strand breaks formed under indirect action conditions cannot serve as pre-mutational damage in DNA.

Reengineering a transmembrane protein to treat muscular dystrophy using exon skipping.

PubMed

Gao, Quan Q; Wyatt, Eugene; Goldstein, Jeff A; LoPresti, Peter; Castillo, Lisa M; Gazda, Alec; Petrossian, Natalie; Earley, Judy U; Hadhazy, Michele; Barefield, David Y; Demonbreun, Alexis R; Bönnemann, Carsten; Wolf, Matthew; McNally, Elizabeth M

2015-11-02

Exon skipping uses antisense oligonucleotides as a treatment for genetic diseases. The antisense oligonucleotides used for exon skipping are designed to bypass premature stop codons in the target RNA and restore reading frame disruption. Exon skipping is currently being tested in humans with dystrophin gene mutations who have Duchenne muscular dystrophy. For Duchenne muscular dystrophy, the rationale for exon skipping derived from observations in patients with naturally occurring dystrophin gene mutations that generated internally deleted but partially functional dystrophin proteins. We have now expanded the potential for exon skipping by testing whether an internal, in-frame truncation of a transmembrane protein γ-sarcoglycan is functional. We generated an internally truncated γ-sarcoglycan protein that we have termed Mini-Gamma by deleting a large portion of the extracellular domain. Mini-Gamma provided functional and pathological benefits to correct the loss of γ-sarcoglycan in a Drosophila model, in heterologous cell expression studies, and in transgenic mice lacking γ-sarcoglycan. We generated a cellular model of human muscle disease and showed that multiple exon skipping could be induced in RNA that encodes a mutant human γ-sarcoglycan. Since Mini-Gamma represents removal of 4 of the 7 coding exons in γ-sarcoglycan, this approach provides a viable strategy to treat the majority of patients with γ-sarcoglycan gene mutations.

Irradiation Maintains Functional Components of Dry Hot Peppers (Capsicum annuum L.) under Ambient Storage

PubMed Central

Iqbal, Qumer; Amjad, Muhammad; Asi, Muhammad Rafique; Nawaz, Aamir; Khan, Samiya Mahmood; Ariño, Agustin; Ahmad, Tanveer

2016-01-01

Hot peppers used as natural flavoring and coloring agents are usually irradiated in prepacked form for decontamination. The effects of gamma radiation on the stability of functional components such as capsaicinoids and antioxidant compounds (carotenoids, ascorbic acid and total phenolics) were investigated in hot peppers (Capsicum annuum). Whole dried peppers packed in polyethylene bags were gamma irradiated at 0 (control), 2, 4, and 6 kGy and subsequently stored at 25 °C for 90 days. The irradiation dose did not substantially affect the initial contents of capsaicinoids, ascorbic acid and total phenolics, though the concentration of carotenoids declined by 8% from the control (76.9 mg/100 g) to 6 kGy radiation dose (70.7 mg/100 g). Similarly, during storage for 90 days at ambient temperature the concentrations of capsaicinoids and total phenolics remained fairly stable with mean percent reductions from 3.3% to 4.2%, while the levels of total carotenoids and ascorbic acid significantly (p < 0.05) declined by 12% and 14%, respectively. Overall, neither irradiation nor subsequent ambient storage could appreciably influence the contents of functional components in hot peppers. These results revealed that gamma irradiation up to 6 kGy can be safely used for decontamination to meet the needs for overseas markets without compromising product quality. PMID:28231158

Irradiation Maintains Functional Components of Dry Hot Peppers (Capsicum annuum L.) under Ambient Storage.

PubMed

Iqbal, Qumer; Amjad, Muhammad; Asi, Muhammad Rafique; Nawaz, Aamir; Khan, Samiya Mahmood; Ariño, Agustin; Ahmad, Tanveer

2016-09-12

Hot peppers used as natural flavoring and coloring agents are usually irradiated in prepacked form for decontamination. The effects of gamma radiation on the stability of functional components such as capsaicinoids and antioxidant compounds (carotenoids, ascorbic acid and total phenolics) were investigated in hot peppers ( Capsicum annuum ). Whole dried peppers packed in polyethylene bags were gamma irradiated at 0 (control), 2, 4, and 6 kGy and subsequently stored at 25 °C for 90 days. The irradiation dose did not substantially affect the initial contents of capsaicinoids, ascorbic acid and total phenolics, though the concentration of carotenoids declined by 8% from the control (76.9 mg/100 g) to 6 kGy radiation dose (70.7 mg/100 g). Similarly, during storage for 90 days at ambient temperature the concentrations of capsaicinoids and total phenolics remained fairly stable with mean percent reductions from 3.3% to 4.2%, while the levels of total carotenoids and ascorbic acid significantly ( p < 0.05) declined by 12% and 14%, respectively. Overall, neither irradiation nor subsequent ambient storage could appreciably influence the contents of functional components in hot peppers. These results revealed that gamma irradiation up to 6 kGy can be safely used for decontamination to meet the needs for overseas markets without compromising product quality.

Reengineering a transmembrane protein to treat muscular dystrophy using exon skipping

PubMed Central

Gao, Quan Q.; Wyatt, Eugene; Goldstein, Jeff A.; LoPresti, Peter; Castillo, Lisa M.; Gazda, Alec; Petrossian, Natalie; Earley, Judy U.; Hadhazy, Michele; Barefield, David Y.; Demonbreun, Alexis R.; Bönnemann, Carsten; Wolf, Matthew; McNally, Elizabeth M.

2015-01-01

Exon skipping uses antisense oligonucleotides as a treatment for genetic diseases. The antisense oligonucleotides used for exon skipping are designed to bypass premature stop codons in the target RNA and restore reading frame disruption. Exon skipping is currently being tested in humans with dystrophin gene mutations who have Duchenne muscular dystrophy. For Duchenne muscular dystrophy, the rationale for exon skipping derived from observations in patients with naturally occurring dystrophin gene mutations that generated internally deleted but partially functional dystrophin proteins. We have now expanded the potential for exon skipping by testing whether an internal, in-frame truncation of a transmembrane protein γ-sarcoglycan is functional. We generated an internally truncated γ-sarcoglycan protein that we have termed Mini-Gamma by deleting a large portion of the extracellular domain. Mini-Gamma provided functional and pathological benefits to correct the loss of γ-sarcoglycan in a Drosophila model, in heterologous cell expression studies, and in transgenic mice lacking γ-sarcoglycan. We generated a cellular model of human muscle disease and showed that multiple exon skipping could be induced in RNA that encodes a mutant human γ-sarcoglycan. Since Mini-Gamma represents removal of 4 of the 7 coding exons in γ-sarcoglycan, this approach provides a viable strategy to treat the majority of patients with γ-sarcoglycan gene mutations. PMID:26457733

A DCM study of spectral asymmetries in feedforward and feedback connections between visual areas V1 and V4 in the monkey.

PubMed

Bastos, A M; Litvak, V; Moran, R; Bosman, C A; Fries, P; Friston, K J

2015-03-01

This paper reports a dynamic causal modeling study of electrocorticographic (ECoG) data that addresses functional asymmetries between forward and backward connections in the visual cortical hierarchy. Specifically, we ask whether forward connections employ gamma-band frequencies, while backward connections preferentially use lower (beta-band) frequencies. We addressed this question by modeling empirical cross spectra using a neural mass model equipped with superficial and deep pyramidal cell populations-that model the source of forward and backward connections, respectively. This enabled us to reconstruct the transfer functions and associated spectra of specific subpopulations within cortical sources. We first established that Bayesian model comparison was able to discriminate between forward and backward connections, defined in terms of their cells of origin. We then confirmed that model selection was able to identify extrastriate (V4) sources as being hierarchically higher than early visual (V1) sources. Finally, an examination of the auto spectra and transfer functions associated with superficial and deep pyramidal cells confirmed that forward connections employed predominantly higher (gamma) frequencies, while backward connections were mediated by lower (alpha/beta) frequencies. We discuss these findings in relation to current views about alpha, beta, and gamma oscillations and predictive coding in the brain. Copyright © 2015. Published by Elsevier Inc.

Stochastic analysis of particle movement over a dune bed

USGS Publications Warehouse

Lee, Baum K.; Jobson, Harvey E.

1977-01-01

Stochastic models are available that can be used to predict the transport and dispersion of bed-material sediment particles in an alluvial channel. These models are based on the proposition that the movement of a single bed-material sediment particle consists of a series of steps of random length separated by rest periods of random duration and, therefore, application of the models requires a knowledge of the probability distributions of the step lengths, the rest periods, the elevation of particle deposition, and the elevation of particle erosion. The procedure was tested by determining distributions from bed profiles formed in a large laboratory flume with a coarse sand as the bed material. The elevation of particle deposition and the elevation of particle erosion can be considered to be identically distributed, and their distribution can be described by either a ' truncated Gaussian ' or a ' triangular ' density function. The conditional probability distribution of the rest period given the elevation of particle deposition closely followed the two-parameter gamma distribution. The conditional probability distribution of the step length given the elevation of particle erosion and the elevation of particle deposition also closely followed the two-parameter gamma density function. For a given flow, the scale and shape parameters describing the gamma probability distributions can be expressed as functions of bed-elevation. (Woodard-USGS)

Time course of gamma-band oscillation associated with face processing in the inferior occipital gyrus and fusiform gyrus: A combined fMRI and MEG study.

PubMed

Uono, Shota; Sato, Wataru; Kochiyama, Takanori; Kubota, Yasutaka; Sawada, Reiko; Yoshimura, Sayaka; Toichi, Motomi

2017-04-01

Debate continues over whether the inferior occipital gyrus (IOG) or the fusiform gyrus (FG) represents the first stage of face processing and what role these brain regions play. We investigated this issue by combining functional magnetic resonance imaging (fMRI) and magnetoencephalography (MEG) in normal adults. Participants passively observed upright and inverted faces and houses. First, we identified the IOG and FG as face-specific regions using fMRI. We applied beamforming source reconstruction and time-frequency analysis to MEG source signals to reveal the time course of gamma-band activations in these regions. The results revealed that the right IOG showed higher gamma-band activation in response to upright faces than to upright houses at 100 ms from the stimulus onset. Subsequently, the right FG showed greater gamma-band response to upright faces versus upright houses at around 170 ms. The gamma-band activation in the right IOG and right FG was larger in response to inverted faces than to upright faces at the later time window. These results suggest that (1) the gamma-band activities occurs rapidly first in the IOG and next in the FG and (2) the gamma-band activity in the right IOG at later time stages is involved in configuration processing for faces. Hum Brain Mapp 38:2067-2079, 2017. © 2017 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Rhythms of Consciousness: Binocular Rivalry Reveals Large-Scale Oscillatory Network Dynamics Mediating Visual Perception

PubMed Central

Doesburg, Sam M.; Green, Jessica J.; McDonald, John J.; Ward, Lawrence M.

2009-01-01

Consciousness has been proposed to emerge from functionally integrated large-scale ensembles of gamma-synchronous neural populations that form and dissolve at a frequency in the theta band. We propose that discrete moments of perceptual experience are implemented by transient gamma-band synchronization of relevant cortical regions, and that disintegration and reintegration of these assemblies is time-locked to ongoing theta oscillations. In support of this hypothesis we provide evidence that (1) perceptual switching during binocular rivalry is time-locked to gamma-band synchronizations which recur at a theta rate, indicating that the onset of new conscious percepts coincides with the emergence of a new gamma-synchronous assembly that is locked to an ongoing theta rhythm; (2) localization of the generators of these gamma rhythms reveals recurrent prefrontal and parietal sources; (3) theta modulation of gamma-band synchronization is observed between and within the activated brain regions. These results suggest that ongoing theta-modulated-gamma mechanisms periodically reintegrate a large-scale prefrontal-parietal network critical for perceptual experience. Moreover, activation and network inclusion of inferior temporal cortex and motor cortex uniquely occurs on the cycle immediately preceding responses signaling perceptual switching. This suggests that the essential prefrontal-parietal oscillatory network is expanded to include additional cortical regions relevant to tasks and perceptions furnishing consciousness at that moment, in this case image processing and response initiation, and that these activations occur within a time frame consistent with the notion that conscious processes directly affect behaviour. PMID:19582165

Fibrinogen Bastia (gamma 318 Asp-->Tyr) a novel abnormal fibrinogen characterized by defective fibrin polymerization.

PubMed

Lounes, K C; Soria, C; Valognes, A; Turchini, M F; Soria, J; Koopman, J

1999-12-01

A new congenital dysfibrinogen, Fibrinogen Bastia, was discovered in a 20-year-old woman with no clinical symptoms. The plasma thrombin-clotting time was severely prolonged. The functional plasma fibrinogen concentration was low (0.2 mg/ml), whereas the immunological concentration was normal (2.9 mg/ml). Purified fibrinogen Bastia displayed a markedly prolonged thrombin-clotting time related to a delayed thrombin-induced fibrin polymerization. Both the thrombin-clotting time and the fibrin polymerization were partially corrected by the addition of calcium ions. The anomaly of fibrinogen Bastia was found to be located in the gamma-chain since by SDS-PAGE performed according to the method of Laemmli two gamma-chains were detected, one normal and one with an apparently lower molecular weight. Furthermore, analysis of plasmin degradation products demonstrated that calcium ions only partially protect fibrinogen Bastia gamma-chain against plasmin digestion, suggesting that the anomaly is located in the C-terminal part of the gamma-chain. Sequence analysis of PCR-amplified genomic DNA fragments of the propositus demonstrated a single base substitution (G-->T) in the exon VIII of the gamma chain gene, resulting in the amino acid substitution 318 Asp (GAC)-->Tyr (TAC). The PCR clones were recloned and 50% of them contained the mutation, indicating that the patient was heterozygous. These data indicate that residue Asp 318 is important for normal fibrin polymerization and the protective effect of calcium ions against plasmin degradation of the C-terminal part of the gamma-chain.

Chronic allograft nephropathy: expression and localization of PAI-1 and PPAR-gamma.

PubMed

Revelo, Monica P; Federspiel, Charles; Helderman, Harold; Fogo, Agnes B

2005-12-01

Chronic allograft nephropathy (CAN) is a major cause of loss of renal allografts. Mechanisms postulated to be involved include sequelae of rejection, warm ischaemia time, drug toxicity, ongoing hypertension and dyslipidaemia. Plasminogen activator inhibitor-1 (PAI-1) is implicated not only in thrombosis, but also in fibrosis, by inhibiting matrix degradation, and is expressed in renal parenchymal cells as well as in macrophages. Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) is a member of the steroid receptor superfamily, and plays a major beneficial role in lipid regulation, insulin sensitivity and macrophage function, factors that may play a role in CAN. We therefore studied the expression of these molecules in CAN. All renal biopsy/nephrectomy files from Vanderbilt and Nashville VAMC from a 6 year period were reviewed to identify all renal transplant biopsies or nephrectomies more than 6 months after transplant with CAN. CAN was defined as fibrosis in the graft, vascular, interstitial or glomerular. All cases were scored for severity of fibrosis in vasculature (0-3 scale), glomeruli (% affected with either segmental and/or global sclerosis) and interstitial fibrosis (% of sample affected). PAI-1 and PPAR-gamma immunostaining was assessed on a 0-3 scale in glomeruli, vessels and tubules. Eighty-two patients with a total of 106 samples met entry criteria. The population consisted of 59 Caucasians and 23 African-Americans; 49 males, 33 females with average age 37.9+/-1.7 years. Average time after transplant at time of biopsy was 60.5+/-4.9 months (range 7-229). Glomerulosclerosis extent in CAN was on average 26.5+/-2.4% compared with 3.6+/-1.2% in normal control kidneys from native kidney cancer nephrectomies and 0% in transplanted kidney biopsies from patients obtained > or =6 months after transplantation without CAN. Native control kidneys showed mild interstitial fibrosis (8.0+/-1.2%), whereas transplant controls showed very minimal fibrosis (2.0+/-2.0%). Interstitial fibrosis in CAN kidneys was on average 47.9+/-2.4%. Glomerular PAI-1 and PPAR-gamma staining scores were markedly increased in CAN (1.8+/-0.1, 2.3+/-0.1, respectively) compared with normal control kidneys from native kidney cancer nephrectomies (PAI-1 0.2+/-0.2 and PPAR-gamma 0.4+/-0.2, P<0.001) and transplanted kidney biopsies from patients obtained > or =6 months after transplantation without CAN (PAI-1 0 and PPAR-gamma 0, P<0.001). Tubular PAI-1 and PPAR-gamma staining scores were 1.9+/-0.1 and 1.9+/-0.1, respectively, and also increased over both native and transplant kidney controls (0.8+/-0.2 for both categories for PAI-1, 1.2+/-0.2 for both categories for PPAR-gamma, respectively). Vascular sclerosis in CAN was 1.0+/-0.1 with increased PAI-1 and PPAR-gamma scores (1.7+/-0.1, 1.2+/-0.1, respectively) compared with controls. Infiltrating macrophages were increased in CAN, and were positive for both PAI-1 and PPAR-gamma. Biopsies with less sclerosis overall showed a trend for less PAI-1 and PPAR-gamma staining. PAI-1 and PPAR-gamma are both increased in CAN compared with non-scarred native or transplant control kidneys. We speculate that altered matrix metabolism and macrophage function might be involved in the development of CAN.

"Missing links" in borderline personality disorder: loss of neural synchrony relates to lack of emotion regulation and impulse control.

PubMed

Williams, Leanne M; Sidis, Anna; Gordon, Evian; Meares, Russell A

2006-05-01

Symptoms of borderline personality disorder (BPD) may reflect distinct breakdowns in the integration of posterior and frontal brain networks. We used a high temporal resolution measure (40-Hz gamma phase synchrony) of brain activity to examine the connectivity of brain function in BPD. Unmedicated patients with BPD (n = 15) and age-and sex-matched healthy control subjects (n = 15) undertook a task requiring discrimination of salient from background tones. In response to salient stimuli, the magnitude and latency of peak gamma phase synchrony for early (0-150 ms post stimulus) and late (250-500 ms post stimulus) phases were calculated for frontal and posterior regions and for left and right hemispheres. We recorded skin conductance responses (SCRs) and reaction time (RT) simultaneously to examine the contribution of arousal and performance. Compared with controls, patients with BPD had a significant delay in early posterior gamma synchrony and a reduction in right hemisphere late gamma synchrony in response to salient stimuli. Both SCR onset and RT were also delayed in BPD, but independently from differences in synchrony. The delay in posterior synchrony was associated with cognitive symptoms, and reduced right hemisphere synchrony was associated with impulsivity. These findings suggest that distinct impairments in the functional connectivity of neural systems for orienting to salient input underlie core dimensions of cognitive disturbance and poor impulse control in BPD.

Visual steady state in relation to age and cognitive function.

PubMed

Horwitz, Anna; Dyhr Thomsen, Mia; Wiegand, Iris; Horwitz, Henrik; Klemp, Marc; Nikolic, Miki; Rask, Lene; Lauritzen, Martin; Benedek, Krisztina

2017-01-01

Neocortical gamma activity is crucial for sensory perception and cognition. This study examines the value of using non-task stimulation-induced EEG oscillations to predict cognitive status in a birth cohort of healthy Danish males (Metropolit) with varying cognitive ability. In particular, we examine the steady-state VEP power response (SSVEP-PR) in the alpha (8Hz) and gamma (36Hz) bands in 54 males (avg. age: 62.0 years) and compare these with 10 young healthy participants (avg. age 27.6 years). Furthermore, we correlate the individual alpha-to-gamma difference in relative visual-area power (ΔRV) with cognitive scores for the older adults. We find that ΔRV decrease with age by just over one standard deviation when comparing young with old participants (p<0.01). Furthermore, intelligence is significantly negatively correlated with ΔRV in the older adult cohort, even when processing speed, global cognition, executive function, memory, and education (p<0.05). In our preferred specification, an increase in ΔRV of one standard deviation is associated with a reduction in intelligence of 48% of a standard deviation (p<0.01). Finally, we conclude that the difference in cerebral rhythmic activity between the alpha and gamma bands is associated with age and cognitive status, and that ΔRV therefore provide a non-subjective clinical tool with which to examine cognitive status in old age.

Visual steady state in relation to age and cognitive function

PubMed Central

Dyhr Thomsen, Mia; Wiegand, Iris; Horwitz, Henrik; Klemp, Marc; Nikolic, Miki; Rask, Lene; Lauritzen, Martin; Benedek, Krisztina

2017-01-01

Neocortical gamma activity is crucial for sensory perception and cognition. This study examines the value of using non-task stimulation-induced EEG oscillations to predict cognitive status in a birth cohort of healthy Danish males (Metropolit) with varying cognitive ability. In particular, we examine the steady-state VEP power response (SSVEP-PR) in the alpha (8Hz) and gamma (36Hz) bands in 54 males (avg. age: 62.0 years) and compare these with 10 young healthy participants (avg. age 27.6 years). Furthermore, we correlate the individual alpha-to-gamma difference in relative visual-area power (ΔRV) with cognitive scores for the older adults. We find that ΔRV decrease with age by just over one standard deviation when comparing young with old participants (p<0.01). Furthermore, intelligence is significantly negatively correlated with ΔRV in the older adult cohort, even when processing speed, global cognition, executive function, memory, and education (p<0.05). In our preferred specification, an increase in ΔRV of one standard deviation is associated with a reduction in intelligence of 48% of a standard deviation (p<0.01). Finally, we conclude that the difference in cerebral rhythmic activity between the alpha and gamma bands is associated with age and cognitive status, and that ΔRV therefore provide a non-subjective clinical tool with which to examine cognitive status in old age. PMID:28245274

A new protocol for functional analysis of adipogenesis using reverse transfection technology and time-lapse video microscopy.

PubMed

Grönniger, Elke; Wessel, Sonja; Kühn, Sonja Christin; Söhle, Jörn; Wenck, Horst; Stäb, Franz; Winnefeld, Marc

2010-07-01

Since the worldwide increase in obesity represents a growing challenge for healthcare systems, research focusing on fat cell metabolism has become a focal point of interest. Here, we describe a small interfering RNA (siRNA)-technology-based screening method to study fat cell differentiation in human primary preadipocytes that could be further developed towards an automated middle-throughput screening procedure. First, we established optimal conditions for the reverse transfection of human primary preadipocytes demonstrating that an efficient reverse transfection of preadipocytes is technically feasible. Aligning the processes of reverse transfection and fat cell differentiation utilizing peroxisome proliferator-activated receptor gamma (PPAR gamma)-siRNA, we showed that preadipocyte differentiation was suppressed by knock-down of PPAR gamma, the key regulator of fat cell differentiation. The use of fluorescently labelled fatty acids in combination with fluorescence time-lapse microscopy over a longer period of time enabled us to quantify the PPAR gamma phenotype. Additionally, our data demonstrate that reverse transfection of human cultured preadipocytes with TIP60 (HIV-1 Tat-interacting protein 60)-siRNA lead to a TIP60 knock-down and subsequently inhibits fat cell differentiation, suggesting a role of this protein in human adipogenesis. In conclusion, we established a protocol that allows for an efficient functional and time-dependent analysis by quantitative time-lapse microscopy to identify novel adipogenesis-associated genes.

Decarboxylation of bovine prothrombin fragment 1 and prothrombin.

PubMed

Tuhy, P M; Bloom, J W; Mann, K G

1979-12-25

Bovine prothrombin fragment 1 and prothrombin undergo decarboxylation of their gamma-carboxyglutamic acid residues when the lyophilized proteins are heated in vacuo at 110 degrees C for several hours. The fully decarboxylated fragment 1 product has lost its barium-binding ability as well as the calcium-binding function which causes fluorescence quenching in the presence of 2 mM Ca2+. There is no sign of secondary structure alteration in solution upon analysis by fluorescence emission and circular dichroic spectroscopy. A family of partially decarboxylated fragment 1 species generated by heating for shorter periods shows that the initial decrease in calcium-binding ability occurs almost twice as rapidly as the loss of gamma-carboxyglutamic acid. This is consistent with the idea that differential functions can be ascribed to the 10 gamma-carboxyglutamic acid residues in fragment 1, including both high- and low-affinity metal ion binding sites. Prothrombin itself also undergoes total decarboxylation without any apparent alteration in secondary structure. However, in this case the latent thrombin activity is progressively diminished during the heating process in terms of both clotting activity and hydrolysis of the amide substrate H-D-Phe-Pip-Arg-pNA. The present results indicate that in vitro decarboxylation of gamma-carboxyglutamic acid in dried proteins is useful for analyzing the detailed calcium-binding proteins of vitamin K dependent coagulation factors.

Changes in barrier function of a model intestinal epithelium by intraepithelial lymphocytes require new protein synthesis by epithelial cells.

PubMed Central

Taylor, C T; Murphy, A; Kelleher, D; Baird, A W

1997-01-01

BACKGROUND: Elements of the mucosal immune system may play an important part in regulating epithelial barrier function in the intestinal tract. Intraepithelial lymphocytes (IELs) represent a subtype of immunocyte which is strategically placed to regulate epithelial function at most mucosal sites. AIMS AND METHODS: An IEL derived cell line (SC1) was used to examine its effects on the model epithelium T84--a tumour derived cell line which retains the phenotype of colonic crypt cells. Transepithelial electrical resistance (TER) was used as a marker of epithelial integrity. RESULTS: Coculture of T84 cells with SC1 produced a significant fall in TER as did exposure of T84 monolayers to IEL derived supernatant. Recombinant interferon-gamma (rIFN gamma) also reduced TER in T84 monolayers. Cycloheximide prevented the effects of IEL supernatant and of rIFN gamma on TER. The fall in TER in response to rIFN gamma was attenuated by blocking antibodies, which did not alter the fall in resistance induced by IEL supernatant. Fractions of IEL supernatant, separated on the basis of size, evoked temporally distinct changes in TER. Ultrastructural studies support the hypothesis that the slow onset but severe fall in TER indicates catastrophic effects on the monolayer. The more rapid onset fall in TER was not associated with gross changes in monolayer morphology. Reduction of TER by IEL supernatant was not influenced by inhibitors of tyrosine phosphatase or of protein kinase C. Although herbimycin did reduce the rapid onset change in TER, the tyrosine kinase inhibitor genistein did not alter responses to IEL supernatant. CONCLUSIONS: Mucosal T cells may influence barrier function by a process involving new protein synthesis by epithelial cells. This model may have relevance in some inflammatory conditions of the gastrointestinal tract. Images PMID:9203943

Evaluation of the structures size in the liquid-gas flow by gamma-ray absorption

NASA Astrophysics Data System (ADS)

Zych, Marcin; Hanus, Robert; Jaszczur, Marek; Świsulski, Dariusz; Petryka, Leszek; Jodłowski, Paweł; Zych, Piotr

2018-06-01

The rapid development of tomography methods particularly electrical, X and gamma rays allows for a wide range of the information about flow structure. However, all of such methods are quite complicated. At the same time much simpler systems as the measuring system of gamma rays absorption, allows to obtain a all key flow information which describe the two-phase flow. In the article the results of analyzes of radiometric signal that not only allow to recognize the type of flow, but also the assessment of forming structures are presented. Calculation and interpretation of the data were based on the crosscorrelation and cross-spectral density function. In order to verify the calculations the photographic documentation made during the measurements was used.

Theoretical study of the NO gamma system

NASA Technical Reports Server (NTRS)

Langhoff, Stephen R.; Bauschlicher, Charles W., Jr.; Partridge, Harry

1988-01-01

A systematic study of the NO gamma system with level of correlation treatment was carried out using large Gaussian basis sets to determine the potential curves for the X2Pi and A2Sigma(+) states of NO. It is shown that the A2Sigma-X2Pi electronic transition moment (gamma system) increases monotonically with decreasing internuclear distance and that the increase in the moment as r decreases is correlated with the increasing degree of diffuse character in the X2Pi state. The results of a study of the X2Pi and A2Sigma(+) dipole moment functions showed that the X2Pi vibrationally averaged dipole moments and the (1-0) and (2-0) vibration-rotation band intensities agree well with experimental data.

SOME DUALITY THEOREMS FOR CYCLOTOMIC \\Gamma-EXTENSIONS OF ALGEBRAIC NUMBER FIELDS OF CM TYPE

NASA Astrophysics Data System (ADS)

Kuz'min, L. V.

1980-06-01

For an odd prime l and a cyclotomic \\Gamma{-}l-extension k_\\infty/k of a field k of CM type, a compact periodic \\Gamma-module A_l(k), analogous to the Tate module of a function field, is defined. The analog of the Weil scalar product is constructed on the module A_l(k). The properties of this scalar product are examined, and certain other duality relations are determined on A_l(k). It is proved that, in a finite l-extension k'/k of CM type, the \\mathbf{Z}_l-ranks of A_l(k) and A_l(k') are connected by a relation similar to the Hurwitz formula for the genus of a curve.Bibliography: 7 titles.

Characterization of CD4 and CD8 T Cell Responses in MuSK Myasthenia Gravis

PubMed Central

Yi, JS; Guidon, A; Sparks, S; Osborne, R; Juel, VC; Massey, JM; Sanders, DB; Weinhold, KJ; Guptill, JT

2014-01-01

Muscle specific tyrosine kinase myasthenia gravis (MuSK MG) is a form of autoimmune MG that predominantly affects women and has unique clinical features, including prominent bulbar weakness, muscle atrophy, and excellent response to therapeutic plasma exchange. Patients with MuSK MG have predominantly IgG4 autoantibodies directed against MuSK on the postsynaptic muscle membrane. Lymphocyte functionality has not been reported in this condition. The goal of this study was to characterize T-cell responses in patients with MuSK MG. Intracellular production of IFN-gamma, TNF-alpha, IL-2, IL-17, and IL-21 by CD4+ and CD8+ T-cells was measured by polychromatic flow cytometry in peripheral blood samples from 11 Musk MG patients and 10 healthy controls. Only one MuSK MG patient was not receiving immunosuppressive therapy. Regulatory T-cells (Treg) were also included in our analysis to determine if changes in T cell function were due to altered Treg frequencies. CD8+ T-cells from MuSK MG patients had higher frequencies of polyfunctional responses than controls, and CD4+ T-cells had higher IL-2, TNF-alpha, and IL-17. MuSK MG patients had a higher percentage of CD4+ T-cells producing combinations of IFN-gamma/IL-2/TNF-gamma, TNF-alpha/IL-2, and IFN-gamma/TNF-alpha. Interestingly, Treg numbers and CD39 expression were not different from control values. MuSK MG patients had increased frequencies of Th1 and Th17 cytokines and were primed for polyfunctional proinflammatory responses that cannot be explained by a defect in Treg function or number. PMID:24378287

Impaired plasmacytoid dendritic cell (PDC)-NK cell activity in viremic human immunodeficiency virus infection attributable to impairments in both PDC and NK cell function.

PubMed

Conry, Sara J; Milkovich, Kimberly A; Yonkers, Nicole L; Rodriguez, Benigno; Bernstein, Helene B; Asaad, Robert; Heinzel, Frederick P; Tary-Lehmann, Magdalena; Lederman, Michael M; Anthony, Donald D

2009-11-01

Human immunodeficiency virus (HIV) and hepatitis C virus (HCV) infections impair plasmacytoid dendritic cell (PDC) and natural killer (NK) cell subset numbers and functions, though little is known about PDC-NK cell interactions during these infections. We evaluated PDC-dependent NK cell killing and gamma interferon (IFN-gamma) and granzyme B production, using peripheral blood mononuclear cell (PBMC)-based and purified cell assays of samples from HCV- and HIV-infected subjects. CpG-enhanced PBMC killing and IFN-gamma and granzyme B activity (dependent on PDC and NK cells) were impaired in viremic HIV infection. In purified PDC-NK cell culture experiments, CpG-enhanced, PDC-dependent NK cell activity was cell contact and IFN-alpha dependent, and this activity was impaired in viremic HIV infection but not in HCV infection. In heterologous PDC-NK cell assays, impaired PDC-NK cell killing activity was largely attributable to an NK cell defect, while impaired PDC-NK cell IFN-gamma-producing activity was attributable to both PDC and NK cell defects. Additionally, the response of NK cells to direct IFN-alpha stimulation was defective in viremic HIV infection, and this defect was not attributable to diminished IFN-alpha receptor expression, though IFN-alpha receptor and NKP30 expression was closely associated with killer activity in viremic HIV infection but not in healthy controls. These data indicate that during uncontrolled HIV infection, PDC-dependent NK cell function is impaired, which is in large part attributable to defective IFN-alpha-induced NK cell activity and not to altered IFN-alpha receptor, NKP30, NKP44, NKP46, or NKG2D expression.

Chromatin organization as an indicator of glucocorticoid induced natural killer cell dysfunction.

PubMed

Misale, Michael S; Witek Janusek, Linda; Tell, Dina; Mathews, Herbert L

2018-01-01

It is well-established that psychological distress reduces natural killer cell immune function and that this reduction can be due to the stress-induced release of glucocorticoids. Glucocorticoids are known to alter epigenetic marks associated with immune effector loci, and are also known to influence chromatin organization. The purpose of this investigation was to assess the effect of glucocorticoids on natural killer cell chromatin organization and to determine the relationship of chromatin organization to natural killer cell effector function, e.g. interferon gamma production. Interferon gamma production is the prototypic cytokine produced by natural killer cells and is known to modulate both innate and adaptive immunity. Glucocorticoid treatment of human peripheral blood mononuclear cells resulted in a significant reduction in interferon gamma production. Glucocorticoid treatment also resulted in a demonstrable natural killer cell nuclear phenotype. This phenotype was localization of the histone, post-translational epigenetic mark, H3K27me3, to the nuclear periphery. Peripheral nuclear localization of H3K27me3 was directly related to cellular levels of interferon gamma. This nuclear phenotype was determined by direct visual inspection and by use of an automated, high through-put technology, the Amnis ImageStream. This technology combines the per-cell information content provided by standard microscopy with the statistical significance afforded by large sample sizes common to standard flow cytometry. Most importantly, this technology provides for a direct assessment of the localization of signal intensity within individual cells. The results demonstrate glucocorticoids to dysregulate natural killer cell function at least in part through altered H3K27me3 nuclear organization and demonstrate H3K27me3 chromatin organization to be a predictive indicator of glucocorticoid induced immune dysregulation of natural killer cells. Copyright © 2017 Elsevier Inc. All rights reserved.

Characterization of EJ-200 plastic scintillators as active background shield for cosmogenic radiation

NASA Astrophysics Data System (ADS)

Tkaczyk, A. H.; Saare, H.; Ipbüker, C.; Schulte, F.; Mastinu, P.; Paepen, J.; Pedersen, B.; Schillebeeckx, P.; Varasano, G.

2018-02-01

This paper describes the characterization of commercially available plastic scintillation detectors to be used as an active shield or veto system to reduce the neutron background resulting from atmospheric muon interactions in low-level nuclear waste assay systems. The shield consists of an array of scintillation detectors surrounding a neutron detection system. Scintillation detectors with different thicknesses are characterized for their response to gamma rays, neutrons, and muons. Response functions to gamma rays were determined and measured in the energy range from 0.6 MeV to 6.0 MeV using radionuclide sources. Neutron response functions were derived from results of time-of-flight measurements at the Van de Graaff accelerator of the INFN Legnaro and from measurements with quasi mono-energetic neutron beams produced at the Van de Graaff accelerator of the JRC Geel. From these data, the light output and resolution functions for protons and electrons were derived. The response to muons was verified by background measurements, i.e. without the presence of any neutron or gamma source. It was found that the muon peak is more pronounced when the detectors are placed horizontally. The results indicate that a scintillator with a minimum thickness of 20 mm is needed to separate events due to atmospheric muons from natural gamma ray background, and contributions due to neutron production in nuclear waste based on only the total energy deposition in the detector. In addition, it was shown that muons can be identified with a coincidence pattern when the detectors are stacked. The effectiveness of the proposed system was demonstrated based on muon induced spallation reactions in a lead sample.

CD94 surface density identifies a functional intermediary between the CD56bright and CD56dim human NK-cell subsets.

PubMed

Yu, Jianhua; Mao, Hsiaoyin C; Wei, Min; Hughes, Tiffany; Zhang, Jianying; Park, Il-kyoo; Liu, Shujun; McClory, Susan; Marcucci, Guido; Trotta, Rossana; Caligiuri, Michael A

2010-01-14

Human CD56(bright) natural killer (NK) cells possess little or no killer immunoglobulin-like receptors (KIRs), high interferon-gamma (IFN-gamma) production, but little cytotoxicity. CD56(dim) NK cells have high KIR expression, produce little IFN-gamma, yet display high cytotoxicity. We hypothesized that, if human NK maturation progresses from a CD56(bright) to a CD56(dim) phenotype, an intermediary NK cell must exist, which demonstrates more functional overlap than these 2 subsets, and we used CD94 expression to test our hypothesis. CD94(high)CD56(dim) NK cells express CD62L, CD2, and KIR at levels between CD56(bright) and CD94(low)CD56(dim) NK cells. CD94(high)CD56(dim) NK cells produce less monokine-induced IFN-gamma than CD56(bright) NK cells but much more than CD94(low)CD56(dim) NK cells because of differential interleukin-12-mediated STAT4 phosphorylation. CD94(high)CD56(dim) NK cells possess a higher level of granzyme B and perforin expression and CD94-mediated redirected killing than CD56(bright) NK cells but lower than CD94(low)CD56(dim) NK cells. Collectively, our data suggest that the density of CD94 surface expression on CD56(dim) NK cells identifies a functional and likely developmental intermediary between CD56(bright) and CD94(low)CD56(dim) NK cells. This supports the notion that, in vivo, human CD56(bright) NK cells progress through a continuum of differentiation that ends with a CD94(low)CD56(dim) phenotype.

Interhemispheric correlations of slow spontaneous neuronal fluctuations revealed in human sensory cortex

PubMed Central

Nir, Yuval; Mukamel, Roy; Dinstein, Ilan; Privman, Eran; Harel, Michal; Fisch, Lior; Gelbard-Sagiv, Hagar; Kipervasser, Svetlana; Andelman, Fani; Neufeld, Miri Y; Kramer, Uri; Arieli, Amos; Fried, Itzhak; Malach, Rafael

2009-01-01

Animal studies have shown robust electrophysiological activity in the sensory cortex in the absence of stimuli or tasks. Similarly, recent human functional magnetic resonance imaging (fMRI) revealed widespread, spontaneously emerging cortical fluctuations. However, it is unknown what neuronal dynamics underlie this spontaneous activity in the human brain. Here we studied this issue by combining bilateral single-unit, local field potentials (LFPs) and intracranial electrocorticography (ECoG) recordings in individuals undergoing clinical monitoring. We found slow (<0.1 Hz, following 1/f-like profiles) spontaneous fluctuations of neuronal activity with significant interhemispheric correlations. These fluctuations were evident mainly in neuronal firing rates and in gamma (40–100 Hz) LFP power modulations. Notably, the interhemispheric correlations were enhanced during rapid eye movement and stage 2 sleep. Multiple intracranial ECoG recordings revealed clear selectivity for functional networks in the spontaneous gamma LFP power modulations. Our results point to slow spontaneous modulations in firing rate and gamma LFP as the likely correlates of spontaneous fMRI fluctuations in the human sensory cortex. PMID:19160509

[Functional significance of high-frequency components of brain electrical activity in the processes of gestalt formation].

PubMed

Dumenko, V N

2002-01-01

A review. Current views of the so-called binding problem, which considers hypothetical mechanisms of perception of sensory stimuli and formation of their corresponding Gestalts (internal images) are discussed. The mechanism of intensification of synchronized reactions of cortical electrical activity in the gamma band frequency (30-80 Hz) is the basis of the most popular point of view of "binding". The article considers the evidence for the functional significance of the high-frequency components exceeding the gamma-range (to 200 Hz) obtained by the author, the origin of these oscillations, and conditions of their focal derivation. The problem of "binding" and stages of instrumental conditioning (a stimulus, perception of the stimulus, and its transformation into a signal) as well as significance of the context in learning and formation of tonic states ensuring the realization of phasic reactions is discussed. Forms of "binding" at the final stage of conditioning (selective attention) are considered. The question is posed as to whether "binding" is exhausted only by the mechanisms of synchronization of activities of large neuronal populations and only in the frequencies of the gamma range.

Hydration effect on ion exchange resin irradiated by swift heavy ions and gamma rays

NASA Astrophysics Data System (ADS)

Boughattas, I.; Labed, V.; Gerenton, A.; Ngono-Ravache, Y.; Dannoux-Papin, A.

2018-06-01

Gamma radiolysis of ion exchange resins (IER) is widely studied since the sixties, as a function of different parameters (resin type, dose, atmosphere, water content …). However, to our knowledge, there are very few data concerning hydrogen emission from anionic and cationic resins irradiated at high Linear Energy Transfers (LET). In the present work, we focus on the influence of hydration on hydrogen emission, in anionic and cationic resins irradiated under inert atmosphere using Swift Heavy Ions (SHI) and gamma irradiations. The radiation chemical yield of molecular hydrogen is nonlinear with water content for both resins. The molecular hydrogen production depends first on the water form in IER (free or linked) and second on the solubility of degradation products. Three steps have been observed: at lower water content where G(H2) is stable, at 50%, G(H2) increases due to reactions between water radiolytic species and the resin functional groups and at high water content, G(H2) decreases probably due to its accumulation in water and its consumption by hydroxyl radicals in the supernatant.

Alterations of cortical GABA neurons and network oscillations in schizophrenia.

PubMed

Gonzalez-Burgos, Guillermo; Hashimoto, Takanori; Lewis, David A

2010-08-01

The hypothesis that alterations of cortical inhibitory gamma-aminobutyric acid (GABA) neurons are a central element in the pathology of schizophrenia has emerged from a series of postmortem studies. How such abnormalities may contribute to the clinical features of schizophrenia has been substantially informed by a convergence with basic neuroscience studies revealing complex details of GABA neuron function in the healthy brain. Importantly, activity of the parvalbumin-containing class of GABA neurons has been linked to the production of cortical network oscillations. Furthermore, growing knowledge supports the concept that gamma band oscillations (30-80 Hz) are an essential mechanism for cortical information transmission and processing. Herein we review recent studies further indicating that inhibition from parvalbumin-positive GABA neurons is necessary to produce gamma oscillations in cortical circuits; provide an update on postmortem studies documenting that deficits in the expression of glutamic acid decarboxylase67, which accounts for most GABA synthesis in the cortex, are widely observed in schizophrenia; and describe studies using novel, noninvasive approaches directly assessing potential relations between alterations in GABA, oscillations, and cognitive function in schizophrenia.

Mechanistic modelling of the inhibitory effect of pH on microbial growth.

PubMed

Akkermans, Simen; Van Impe, Jan F

2018-06-01

Modelling and simulation of microbial dynamics as a function of processing, transportation and storage conditions is a useful tool to improve microbial food safety and quality. The goal of this research is to improve an existing methodology for building mechanistic predictive models based on the environmental conditions. The effect of environmental conditions on microbial dynamics is often described by combining the separate effects in a multiplicative way (gamma concept). This idea was extended further in this work by including the effects of the lag and stationary growth phases on microbial growth rate as independent gamma factors. A mechanistic description of the stationary phase as a function of pH was included, based on a novel class of models that consider product inhibition. Experimental results on Escherichia coli growth dynamics indicated that also the parameters of the product inhibition equations can be modelled with the gamma approach. This work has extended a modelling methodology, resulting in predictive models that are (i) mechanistically inspired, (ii) easily identifiable with a limited work load and (iii) easily extended to additional environmental conditions. Copyright © 2017. Published by Elsevier Ltd.

Investigation of runaway electron dissipation in DIII-D using a gamma ray imager

NASA Astrophysics Data System (ADS)

Lvovskiy, A.; Paz-Soldan, C.; Eidietis, N.; Pace, D.; Taussig, D.

2017-10-01

We report the findings of a novel gamma ray imager (GRI) to study runaway electron (RE) dissipation in the quiescent regime on the DIII-D tokamak. The GRI measures the bremsstrahlung emission by RE providing information on RE energy spectrum and distribution across a poloidal cross-section. It consists of a lead pinhole camera illuminating a matrix of BGO detectors placed in the DIII-D mid-plane. The number of detectors was recently doubled to provide better spatial resolution and additional detector shielding was implemented to reduce un-collimated gamma flux and increase single-to-noise ratio. Under varying loop voltage, toroidal magnetic field and plasma density, a non-monotonic RE distribution function has been revealed as a result of the interplay between electric field, synchrotron radiation and collisional damping. A fraction of the high-energy RE population grows forming a bump at the RE distribution function while synchrotron radiation decreases. A possible destabilizing effect of Parail-Pogutse instability on the RE population will be also discussed. Work supported by the US DOE under DE-FC02-04ER54698.

ADP-ribosylation of transducin by pertussis toxin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watkins, P.A.; Burns, D.L.; Kanaho, Y.

1985-11-05

Transducin, the guanyl nucleotide-binding regulatory protein of retinal rod outer segments that couples the photon receptor, rhodopsin, with the light-activated cGMP phosphodiesterase, can be resolved into two functional components, T alpha and T beta gamma. T alpha (39 kDa), which is (TSP)ADP-ribosylated by pertussis toxin and (TSP)NAD in rod outer segments and in purified transducin, was also labeled by the toxin after separation from T beta gamma (36 kDa and approximately 10 kDa); neither component of T beta gamma was a pertussis toxin substrate. Labeling of T alpha was enhanced by T beta gamma and was maximal at approximately 1:1more » molar ratio of T alpha : T beta gamma. Limited proteolysis by trypsin of T alpha in the presence of guanyl-5'-yl imidodiphosphate (Gpp(NH)p) resulted in the sequential appearance of proteins of 38 and TS kDa. The amino terminus of both 38- and TS-kDa proteins was leucine, whereas that of T alpha could not be identified and was assumed to be blocked. The TS-kDa peptide was not a pertussis toxin substrate. Labeling of the 38-kDa protein was poor and was not enhanced by T beta gamma. Trypsin treatment of (TSP)ADP-ribosyl-T alpha produced a labeled 37-38-kDa doublet followed by appearance of radioactivity at the dye front. It appears, therefore, that, although the 38-kDa protein was poor toxin substrate, it contained the ADP-ribosylation site. Without rhodopsin, labeling of T alpha (in the presence of T beta gamma) was unaffected by Gpp(NH)p, guanosine 5'-O-(thiotriphosphate) (GTP gamma S), GTP, GDP, and guanosine 5'-O-(thiodiphosphate) (GDP beta S) but was increased by ATP. When photolyzed rhodopsin and T beta gamma were present, Gpp(NH)p and GTP gamma S decreased (TSP)ADP-ribosylation by pertussis toxin. Thus, pertussis toxin-catalyzed (TSP)ADP-ribosylation of T alpha was affected by nucleotides, rhodopsin and light in addition to T beta gamma.« less

Neuronal correlates of ketamine and walking induced gamma oscillations in the medial prefrontal cortex and mediodorsal thalamus.

PubMed

Furth, Katrina E; McCoy, Alex J; Dodge, Caroline; Walters, Judith R; Buonanno, Andres; Delaville, Claire

2017-01-01

Alterations in the function of the medial prefrontal cortex (mPFC) and its major thalamic source of innervation, the mediodorsal (MD) thalamus, have been hypothesized to contribute to the symptoms of schizophrenia. The NMDAR antagonist ketamine, used to model schizophrenia, elicits a brain state resembling early stage schizophrenia characterized by cognitive deficits and increases in cortical low gamma (40-70 Hz) power. Here we sought to determine how ketamine differentially affects spiking and gamma local field potential (LFP) activity in the rat mPFC and MD thalamus. Additionally, we investigated the ability of drugs targeting the dopamine D4 receptor (D4R) to modify the effects of ketamine on gamma activity as a measure of potential cognitive therapeutic efficacy. Rats were trained to walk on a treadmill to reduce confounds related to hyperactivity after ketamine administration (10 mg/kg s.c.) while recordings were obtained from electrodes chronically implanted in the mPFC and MD thalamus. Ketamine increased gamma LFP power in mPFC and MD thalamus in a similar frequency range, yet did not increase thalamocortical synchronization. Ketamine also increased firing rates and spike synchronization to gamma oscillations in the mPFC but decreased both measures in MD thalamus. Conversely, walking alone increased both firing rates and spike-gamma LFP correlations in both mPFC and MD thalamus. The D4R antagonist alone (L-745,870) had no effect on gamma LFP power during treadmill walking, although it reversed increases induced by the D4R agonist (A-412997) in both mPFC and MD thalamus. Neither drug altered ketamine-induced changes in gamma power or firing rates in the mPFC. However, in MD thalamus, the D4R agonist increased ketamine-induced gamma power and prevented ketamine's inhibitory effect on firing rates. Results provide new evidence that ketamine differentially modulates spiking and gamma power in MD thalamus and mPFC, supporting a potential role for both areas in contributing to ketamine-induced schizophrenia-like symptoms.

Neuronal correlates of ketamine and walking induced gamma oscillations in the medial prefrontal cortex and mediodorsal thalamus

PubMed Central

McCoy, Alex J.; Dodge, Caroline; Walters, Judith R.; Buonanno, Andres; Delaville, Claire

2017-01-01

Alterations in the function of the medial prefrontal cortex (mPFC) and its major thalamic source of innervation, the mediodorsal (MD) thalamus, have been hypothesized to contribute to the symptoms of schizophrenia. The NMDAR antagonist ketamine, used to model schizophrenia, elicits a brain state resembling early stage schizophrenia characterized by cognitive deficits and increases in cortical low gamma (40–70 Hz) power. Here we sought to determine how ketamine differentially affects spiking and gamma local field potential (LFP) activity in the rat mPFC and MD thalamus. Additionally, we investigated the ability of drugs targeting the dopamine D4 receptor (D4R) to modify the effects of ketamine on gamma activity as a measure of potential cognitive therapeutic efficacy. Rats were trained to walk on a treadmill to reduce confounds related to hyperactivity after ketamine administration (10 mg/kg s.c.) while recordings were obtained from electrodes chronically implanted in the mPFC and MD thalamus. Ketamine increased gamma LFP power in mPFC and MD thalamus in a similar frequency range, yet did not increase thalamocortical synchronization. Ketamine also increased firing rates and spike synchronization to gamma oscillations in the mPFC but decreased both measures in MD thalamus. Conversely, walking alone increased both firing rates and spike-gamma LFP correlations in both mPFC and MD thalamus. The D4R antagonist alone (L-745,870) had no effect on gamma LFP power during treadmill walking, although it reversed increases induced by the D4R agonist (A-412997) in both mPFC and MD thalamus. Neither drug altered ketamine-induced changes in gamma power or firing rates in the mPFC. However, in MD thalamus, the D4R agonist increased ketamine-induced gamma power and prevented ketamine’s inhibitory effect on firing rates. Results provide new evidence that ketamine differentially modulates spiking and gamma power in MD thalamus and mPFC, supporting a potential role for both areas in contributing to ketamine-induced schizophrenia-like symptoms. PMID:29095852

Gamma rays induce DNA damage and oxidative stress associated with impaired growth and reproduction in the copepod Tigriopus japonicus.

PubMed

Han, Jeonghoon; Won, Eun-Ji; Lee, Bo-Young; Hwang, Un-Ki; Kim, Il-Chan; Yim, Joung Han; Leung, Kenneth Mei Yee; Lee, Yong Sung; Lee, Jae-Seong

2014-07-01

Nuclear radioisotope accidents are potentially ecologically devastating due to their impact on marine organisms. To examine the effects of exposure of a marine organism to radioisotopes, we irradiated the intertidal copepod Tigriopus japonicus with several doses of gamma radiation and analyzed the effects on mortality, fecundity, and molting by assessing antioxidant enzyme activities and gene expression patterns. No mortality was observed at 96h, even in response to exposure to a high dose (800Gy) of radiation, but mortality rate was significantly increased 120h (5 days) after exposure to 600 or 800Gy gamma ray radiation. We observed a dose-dependent reduction in fecundity of ovigerous females; even the group irradiated with 50Gy showed a significant reduction in fecundity, suggesting that gamma rays are likely to have a population level effect. In addition, we observed growth retardation, particularly at the nauplius stage, in individuals after gamma irradiation. In fact, nauplii irradiated with more than 200Gy, though able to molt to copepodite stage 1, did not develop into adults. Upon gamma radiation, T. japonicus showed a dose-dependent increase in reactive oxygen species (ROS) levels, the activities of several antioxidant enzymes, and expression of double-stranded DNA break damage genes (e.g. DNA-PK, Ku70, Ku80). At a low level (sub-lethal dose) of gamma irradiation, we found dose-dependent upregulation of p53, implying cellular damage in T. japonicus in response to sub-lethal doses of gamma irradiation, suggesting that T. japonicus is not susceptible to sub-lethal doses of gamma irradiation. Additionally, antioxidant genes, phase II enzyme (e.g. GSTs), and cellular chaperone genes (e.g. Hsps) that are involved in cellular defense mechanisms also showed the same expression patterns for sublethal doses of gamma irradiation (50-200Gy). These findings indicate that sublethal doses of gamma radiation can induce oxidative stress-mediated DNA damage and increase the expression of antioxidant enzymes and proteins with chaperone-related functions, thereby significantly affecting life history parameters such as fecundity and molting in the copepod T. japonicus. Copyright © 2014 Elsevier B.V. All rights reserved.

Initial mass functions from ultraviolet stellar photometry: A comparison of Lucke and Hodge OB associations near 30 Doradus with the nearby field

NASA Technical Reports Server (NTRS)

Hill, Jesse K.; Isensee, Joan E.; Cornett, Robert H.; Bohlin, Ralph C.; O'Connell, Robert W.; Roberts, Morton S.; Smith, Andrew M.; Stecher, Theodore P.

1994-01-01

UV stellar photometry is presented for 1563 stars within a 40 minutes circular field in the Large Magellanic Cloud (LMC), excluding the 10 min x 10 min field centered on R136 investigated earlier by Hill et al. (1993). Magnitudes are computed from images obtained by the Ultraviolet Imaging Telescope (UIT) in bands centered at 1615 A and 2558 A. Stellar masses and extinctions are estimated for the stars in associations using the evolutionary models of Schaerer et al. (1993), assuming the age is 4 Myr and that the local LMC extinction follows the Fitzpatrick (1985) 30 Dor extinction curve. The estimated slope of the initial mass function (IMF) for massive stars (greater than 15 solar mass) within the Lucke and Hodge (LH) associations is Gamma = -1.08 +/- 0.2. Initial masses and extinctions for stars not within LH associations are estimated assuming that the stellar age is either 4 Myr or half the stellar lifetime, whichever is larger. The estimated slope of the IMF for massive stars not within LH associations is Gamma = -1.74 +/- 0.3 (assuming continuous star formation), compared with Gamma = -1.35, and Gamma = -1.7 +/- 0.5, obtained for the Galaxy by Salpeter (1955) and Scalo (1986), respectively, and Gamma = -1.6 obtained for massive stars in the Galaxy by Garmany, Conti, & Chiosi (1982). The shallower slope of the association IMF suggests that not only is the star formation rate higher in associations, but that the local conditions favor the formation of higher mass stars there. We make no corrections for binaries or incompleteness.

Structural reorganization of the interleukin-7 signaling complex

DOE Office of Scientific and Technical Information (OSTI.GOV)

McElroy, Craig A.; Holland, Paul J.; Zhao, Peng

2012-06-29

We report here an unliganded receptor structure in the common gamma-chain ({gamma}{sub c}) family of receptors and cytokines. The crystal structure of the unliganded form of the interleukin-7 alpha receptor (IL-7R{alpha}) extracellular domain (ECD) at 2.15 {angstrom} resolution reveals a homodimer forming an 'X' geometry looking down onto the cell surface with the C termini of the two chains separated by 110 {angstrom} and the dimer interface comprising residues critical for IL-7 binding. Further biophysical studies indicate a weak association of the IL-7R{alpha} ECDs but a stronger association between the {gamma}{sub c}/IL-7R{alpha} ECDs, similar to previous studies of the full-lengthmore » receptors on CD4{sup +} T cells. Based on these and previous results, we propose a molecular mechanism detailing the progression from the inactive IL-7R{alpha} homodimer and IL-7R{alpha}-{gamma}{sub c} heterodimer to the active IL-7-IL-7R{alpha}-{gamma}{sub c} ternary complex whereby the two receptors undergo at least a 90{sup o} rotation away from the cell surface, moving the C termini of IL-7R{alpha} and {gamma}{sub c} from a distance of 110 {angstrom} to less than 30 {angstrom} at the cell surface. This molecular mechanism can be used to explain recently discovered IL-7- and {gamma}{sub c}-independent gain-of-function mutations in IL-7R{alpha} from B- and T-cell acute lymphoblastic leukemia patients. The mechanism may also be applicable to other {gamma}{sub c} receptors that form inactive homodimers and heterodimers independent of their cytokines.« less

Transcranial alternating current stimulation modulates auditory temporal resolution in elderly people.

PubMed

Baltus, Alina; Vosskuhl, Johannes; Boetzel, Cindy; Herrmann, Christoph Siegfried

2018-05-13

Recent research provides evidence for a functional role of brain oscillations for perception. For example, auditory temporal resolution seems to be linked to individual gamma frequency of auditory cortex. Individual gamma frequency not only correlates with performance in between-channel gap detection tasks but can be modulated via auditory transcranial alternating current stimulation. Modulation of individual gamma frequency is accompanied by an improvement in gap detection performance. Aging changes electrophysiological frequency components and sensory processing mechanisms. Therefore, we conducted a study to investigate the link between individual gamma frequency and gap detection performance in elderly people using auditory transcranial alternating current stimulation. In a within-subject design, twelve participants were electrically stimulated with two individualized transcranial alternating current stimulation frequencies: 3 Hz above their individual gamma frequency (experimental condition) and 4 Hz below their individual gamma frequency (control condition) while they were performing a between-channel gap detection task. As expected, individual gamma frequencies correlated significantly with gap detection performance at baseline and in the experimental condition, transcranial alternating current stimulation modulated gap detection performance. In the control condition, stimulation did not modulate gap detection performance. In addition, in elderly, the effect of transcranial alternating current stimulation on auditory temporal resolution seems to be dependent on endogenous frequencies in auditory cortex: elderlies with slower individual gamma frequencies and lower auditory temporal resolution profit from auditory transcranial alternating current stimulation and show increased gap detection performance during stimulation. Our results strongly suggest individualized transcranial alternating current stimulation protocols for successful modulation of performance. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Polychronakos statistics and α-deformed Bose condensation of α-bosons

NASA Astrophysics Data System (ADS)

Chung, Won Sang; Hassanabadi, Hassan

2018-02-01

In this paper, we consider the Polychronakos statistics for α < 0. We use the Stirling formula for the α-Gamma function to find the distribution function for the α-bosons. As application, we discuss the α-deformed Bose condensation for α-boson gas.

Metabolic functions of AMPK: aspects of structure and of natural mutations in the regulatory gamma subunits.

PubMed

Moffat, Cynthia; Harper, Mary Ellen

2010-10-01

AMP-activated protein kinase, AMPK, is widely accepted as the master regulator of energy levels within the cell. Responding quickly to changing energy demands, AMPK works to restore levels of ATP during times of cellular stress by promoting ATP producing catabolic pathways and inhibiting ATP consuming anabolic ones. As a heterotrimeric protein complex, AMPK's subunits each act in unique and crucial ways to control AMPK function and its localization within the cell. Research in the last decade has identified and begun to characterize the impact of naturally occurring mutations in the gamma regulatory subunits. Mutations in the γ2 subunit have implications for cardiac function and disease, while the R225W mutation in the γ3 subunit have implications for skeletal muscle fuel metabolism and resistance to fatigue. Research focused on structure-function aspects of AMPK regulatory subunits will lead to a better understanding of the roles of AMPK in health and disease.

Electron-pair-production cross section in the tip region of the positron spectrum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sud, K.K.; Sharma, D.K.

1984-11-01

The radial integrals for electron-pair production in a point Coulomb potential have been expressed by Sud, Sharma, and Sud in terms of the matrix generalization of the GAMMA function. Two new partial differential equations in photon energy satisfied by the matrix GAMMA function are obtained. We have obtained, on integrating the partial differential equations, accurate radial integrals as a function of photon energy for the pair production by intermediate-energy photons. The cross section in the tip region of the spectrum are calculated for photons of energy 5.0 to 10.0 MeV for /sup 92/U. The new technique results in extensive savingmore » in computer time as the basic radial integrals in terms of the hypergeometric function F/sub 2/ are computed at one photon energy for each pair of partial waves. The results of our calculations are compared with plane-wave Born-approximation results and with the calculations of Dugne and of Deck, Moroi, and Alling.« less

Implication of observed cloud variability for parameterizations of microphysical and radiative transfer processes in climate models

NASA Astrophysics Data System (ADS)

Huang, D.; Liu, Y.

2014-12-01

The effects of subgrid cloud variability on grid-average microphysical rates and radiative fluxes are examined by use of long-term retrieval products at the Tropical West Pacific (TWP), Southern Great Plains (SGP), and North Slope of Alaska (NSA) sites of the Department of Energy's Atmospheric Radiation Measurement (ARM) Program. Four commonly used distribution functions, the truncated Gaussian, Gamma, lognormal, and Weibull distributions, are constrained to have the same mean and standard deviation as observed cloud liquid water content. The PDFs are then used to upscale relevant physical processes to obtain grid-average process rates. It is found that the truncated Gaussian representation results in up to 30% mean bias in autoconversion rate whereas the mean bias for the lognormal representation is about 10%. The Gamma and Weibull distribution function performs the best for the grid-average autoconversion rate with the mean relative bias less than 5%. For radiative fluxes, the lognormal and truncated Gaussian representations perform better than the Gamma and Weibull representations. The results show that the optimal choice of subgrid cloud distribution function depends on the nonlinearity of the process of interest and thus there is no single distribution function that works best for all parameterizations. Examination of the scale (window size) dependence of the mean bias indicates that the bias in grid-average process rates monotonically increases with increasing window sizes, suggesting the increasing importance of subgrid variability with increasing grid sizes.

Phencyclidine administration during neurodevelopment alters network activity in prefrontal cortex and hippocampus in adult rats.

PubMed

Kjaerby, Celia; Hovelsø, Nanna; Dalby, Nils Ole; Sotty, Florence

2017-08-01

Symptoms of schizophrenia have been linked to insults during neurodevelopment such as NMDA receptor (NMDAR) antagonist exposure. In animal models, this leads to schizophrenia-like behavioral symptoms as well as molecular and functional changes within hippocampal and prefrontal regions. The aim of this study was to determine how administration of the NMDAR antagonist phencyclidine (PCP) during neurodevelopment affects functional network activity within the hippocampus and medial prefrontal cortex (mPFC). We recorded field potentials in vivo after electrical brain stem stimulation and observed a suppression of evoked theta power in ventral hippocampus, while evoked gamma power in mPFC was enhanced in rats administered with PCP neonatally. In addition, increased gamma synchrony elicited by acute administration of the NMDAR antagonist MK-801 was exaggerated in neonatal PCP animals. These data suggest that NMDAR antagonist exposure during brain development alters functional networks within hippocampus and mPFC possibly contributing to the reported behavioral symptoms of this animal model of schizophrenia. NEW & NOTEWORTHY We show that insults with a NMDA receptor antagonist during neurodevelopment lead to suppressed evoked theta oscillations in ventral hippocampus in adult rats, while evoked gamma oscillations are enhanced and hypersensitive to an acute challenge with a NMDA receptor antagonist in prefrontal cortex. These observations reveal the significance of neurodevelopmental disturbances in the evolvement of schizophrenia-like symptoms and contribute to the understanding of the functional deficits underlying aberrant behavior in this disease. Copyright © 2017 the American Physiological Society.

CaiT of Escherichia coli, a new transporter catalyzing L-carnitine/gamma -butyrobetaine exchange.

PubMed

Jung, Heinrich; Buchholz, Marion; Clausen, Jurgen; Nietschke, Monika; Revermann, Anne; Schmid, Roland; Jung, Kirsten

2002-10-18

l-Carnitine is essential for beta-oxidation of fatty acids in mitochondria. Bacterial metabolic pathways are used for the production of this medically important compound. Here, we report the first detailed functional characterization of the caiT gene product, a putative transport protein whose function is required for l-carnitine conversion in Escherichia coli. The caiT gene was overexpressed in E. coli, and the gene product was purified by affinity chromatography and reconstituted into proteoliposomes. Functional analyses with intact cells and proteoliposomes demonstrated that CaiT is able to catalyze the exchange of l-carnitine for gamma-butyrobetaine, the excreted end product of l-carnitine conversion in E. coli, and related betaines. Electrochemical ion gradients did not significantly stimulate l-carnitine uptake. Analysis of l-carnitine counterflow yielded an apparent external K(m) of 105 microm and a turnover number of 5.5 s(-1). Contrary to related proteins, CaiT activity was not modulated by osmotic stress. l-Carnitine binding to CaiT increased the protein fluorescence and caused a red shift in the emission maximum, an observation explained by ligand-induced conformational alterations. The fluorescence effect was specific for betaine structures, for which the distance between trimethylammonium and carboxyl groups proved to be crucial for affinity. Taken together, the results suggest that CaiT functions as an exchanger (antiporter) for l-carnitine and gamma-butyrobetaine according to the substrate/product antiport principle.

Characterization of the Gamma Response of a Cadmium Capture-gated Neutron Spectrometer

NASA Astrophysics Data System (ADS)

Hogan, Nathaniel; Rees, Lawrence; Czirr, Bart; Bastola, Suraj

2010-10-01

We have studied the gamma response of a newly developed capture-gated neutron spectrometer. Such spectrometers detect a dual signal from incoming neutrons, allowing for differentiation between other particles, such as gamma rays. The neutron provides a primary light pulse in either plastic or liquid scintillator through neutron-proton collisions. A capture material then delivers a second pulse as the moderated neutron captures in the intended material, which then de-excites with the release of gamma energy. The presented spectrometer alternates one centimeter thick plastic scintillators with sheets of cadmium inserted in between for neutron capture. The neutron capture in cadmium offers a release of gamma energy ˜ 9 MeV. To verify that the interaction was caused by a neutron, the response functions of both events must be well known. Due to the prior existence of many capture-gated neutron spectrometers, the proton recoil pulse has already been studied, but the capture pulse is unique to each spectrometer and must be measured. Experimental results agree with theoretical Monte-Carlo code, both suggesting that the optics and geometry of the spectrometer play a large role in its efficiency. Results prove promising for the efficiency of the spectrometer.

Spectral properties of blast-wave models of gamma-ray burst sources

NASA Technical Reports Server (NTRS)

Meszaros, P.; Rees, M. J.; Papathanassiou, H.

1994-01-01

We calculate the spectrum of blast-wave models of gamma-ray burst sources, for various assumptions about the magnetic field density and the relativistic particle acceleration efficiency. For a range of physically plausible models we find that the radiation efficiency is high and leads to nonthermal spectra with breaks at various energies comparable to those observed in the gamma-ray range. Radiation is also predicted at other wavebands, in particular at X-ray, optical/UV, and GeV/TeV energies. We discuss the spectra as a function of duration for three basic types of models, and for cosmological, halo, and galactic disk distances. We also evaluate the gamma-ray fluences and the spectral characteristics for a range of external densities. Impulsive burst models at cosmological distances can satisfy the conventional X-ray paucity constraint S(sub x)/S(sub gamma)less than a few percent over a wide range of durations, but galactic models can do so only for bursts shorter than a few seconds, unless additional assumptions are made. The emissivity is generally larger for bursts in a denser external environment, with the efficiency increasing up to the point where all the energy input is radiated away.

Establishment of Imaging Spectroscopy of Nuclear Gamma-Rays based on Geometrical Optics

PubMed Central

Tanimori, Toru; Mizumura, Yoshitaka; Takada, Atsushi; Miyamoto, Shohei; Takemura, Taito; Kishimoto, Tetsuro; Komura, Shotaro; Kubo, Hidetoshi; Kurosawa, Shunsuke; Matsuoka, Yoshihiro; Miuchi, Kentaro; Mizumoto, Tetsuya; Nakamasu, Yuma; Nakamura, Kiseki; Parker, Joseph D.; Sawano, Tatsuya; Sonoda, Shinya; Tomono, Dai; Yoshikawa, Kei

2017-01-01

Since the discovery of nuclear gamma-rays, its imaging has been limited to pseudo imaging, such as Compton Camera (CC) and coded mask. Pseudo imaging does not keep physical information (intensity, or brightness in Optics) along a ray, and thus is capable of no more than qualitative imaging of bright objects. To attain quantitative imaging, cameras that realize geometrical optics is essential, which would be, for nuclear MeV gammas, only possible via complete reconstruction of the Compton process. Recently we have revealed that “Electron Tracking Compton Camera” (ETCC) provides a well-defined Point Spread Function (PSF). The information of an incoming gamma is kept along a ray with the PSF and that is equivalent to geometrical optics. Here we present an imaging-spectroscopic measurement with the ETCC. Our results highlight the intrinsic difficulty with CCs in performing accurate imaging, and show that the ETCC surmounts this problem. The imaging capability also helps the ETCC suppress the noise level dramatically by ~3 orders of magnitude without a shielding structure. Furthermore, full reconstruction of Compton process with the ETCC provides spectra free of Compton edges. These results mark the first proper imaging of nuclear gammas based on the genuine geometrical optics. PMID:28155870

Photospheric Emission in the Joint GBM and Konus Prompt Spectra of GRB 120323A

NASA Technical Reports Server (NTRS)

Guiriec, S.; Gehrels, N.; McEnery, J.; Kouveliotou, C.; Hartmann, D. H.

2017-01-01

GRB 120323A is a very intense short gamma-ray burst (GRB) detected simultaneously during its prompt gamma-ray emission phase with the Gamma-Ray Burst Monitor (GBM) on board the Fermi Gamma-Ray Space Telescope and the Konus experiment on board the Wind satellite. GBM and Konus operate in the kiloelectronvolt - megaelectronvolt regime; however, the GBM range is broader toward both the low and the high parts of the gamma-ray spectrum. Analyses of such bright events provide a unique opportunity to check the consistency of the data analysis as well as cross-calibrate the two instruments. We performed time-integrated and coarse time-resolved spectral analysis of GRB 120323A prompt emission. We conclude that the analyses of GBM and Konus data are only consistent when using a double-hump spectral shape for both data sets; in contrast, the single hump of the empirical Band function, traditionally used to fit GRB prompt emission spectra, leads to significant discrepancies between GBM and Konus analysis results. Our two-hump model is a combination of a thermal-like and a non-thermal component. We interpret the first component as a natural manifestation of the jet photospheric emission.

Establishment of Imaging Spectroscopy of Nuclear Gamma-Rays based on Geometrical Optics.

PubMed

Tanimori, Toru; Mizumura, Yoshitaka; Takada, Atsushi; Miyamoto, Shohei; Takemura, Taito; Kishimoto, Tetsuro; Komura, Shotaro; Kubo, Hidetoshi; Kurosawa, Shunsuke; Matsuoka, Yoshihiro; Miuchi, Kentaro; Mizumoto, Tetsuya; Nakamasu, Yuma; Nakamura, Kiseki; Parker, Joseph D; Sawano, Tatsuya; Sonoda, Shinya; Tomono, Dai; Yoshikawa, Kei

2017-02-03

Since the discovery of nuclear gamma-rays, its imaging has been limited to pseudo imaging, such as Compton Camera (CC) and coded mask. Pseudo imaging does not keep physical information (intensity, or brightness in Optics) along a ray, and thus is capable of no more than qualitative imaging of bright objects. To attain quantitative imaging, cameras that realize geometrical optics is essential, which would be, for nuclear MeV gammas, only possible via complete reconstruction of the Compton process. Recently we have revealed that "Electron Tracking Compton Camera" (ETCC) provides a well-defined Point Spread Function (PSF). The information of an incoming gamma is kept along a ray with the PSF and that is equivalent to geometrical optics. Here we present an imaging-spectroscopic measurement with the ETCC. Our results highlight the intrinsic difficulty with CCs in performing accurate imaging, and show that the ETCC surmounts this problem. The imaging capability also helps the ETCC suppress the noise level dramatically by ~3 orders of magnitude without a shielding structure. Furthermore, full reconstruction of Compton process with the ETCC provides spectra free of Compton edges. These results mark the first proper imaging of nuclear gammas based on the genuine geometrical optics.

Apoptosis of Trypanosoma musculi co-cultured with LPS activated macrophages: enhanced expression of nitric oxide synthase INF-gamma and caspase.

PubMed

Gugssa, A; Gebru, S; Lee, C M; Baccetti, B; Anderson, W

2005-08-01

Trypanosoma musculi-macrophage co-cultures were studied to investigate the biological role of lipopolysaccharide (LPS) induced cytokines in controlling the proliferation of parasites in vitro. Macrophages, isolated by peritoneal lavage, sustained the growth and proliferation of the parasites. Macrophages activated with LPS were characterized by up-regulation of nitric oxide synthase (iNOS) and phagocytosis of fluorescent latex spheres. Activated macrophages showed marked inhibition of the association and proliferation of the parasites. The LPS treated macrophages produced cytokines, especially interferon gamma (INF-gamma), which was detected by Western blot. Trypanosomes, inhibited from association with macrophages, did not proliferate and instead formed clusters held together by their flagella. Cells in these clusters were apoptotic, as demonstrated by the Apoptag reaction and gel fragmentation assay. In addition, high levels of caspase 8 and caspase 3 were shown in floating trypanosome clusters. The results would suggest that INF-gamma and other cytokines released by activated macrophages, possibly functioning through the INF-gammaR1, Fas ligand, CD95 or other death ligands in the trypanosome plasma membrane initiates the apoptosis cascade in trypanosomes.

Heterogeneity of neutrophil antibodies in patients with primary Sjögren's syndrome.

PubMed

Lamour, A; Le Corre, R; Pennec, Y L; Cartron, J; Youinou, P

1995-11-01

Our aims were to determine the prevalence of neutrophil antibodies in patients with primary Sjögren's syndrome (pSS), identify their target antigen(s), and evaluate their functional significance. Neutrophil antibodies were detected using an indirect immunofluorescence (IIIF) test and an enzyme-linked immunosorbent assay (ELISA), using recombinant human Fc-gamma receptor (Fc gamma RIIIb) as a capture agent. Luminol-dependent chemiluminescence was then measured by an established technique. Antibodies to neutrophils were detected in 30 of 66 patients (45%) and categorized on the basis of positivity for the two assays: IIF+/ELISA+ (group A: five patients), IIF+/ELISA- (group B: five patients), and IFF-/ELISA+ (group C: 20 patients). All positive sera contained antibodies directed to the neutrophil specific Fc gamma RIIIb, and none of them bound to NAnull neutrophils. The titer of neutrophil-reactive antibodies (groups A and B) showed no correlation with the neutrophil count, but these autoantibodies did reduce the cell ability to generate a respiratory burst. Thus, neutrophil antibodies are common in patients with pSS. Their main target appears to be Fc gamma RIII, and this may partly account for the dysfunction in Fc gamma R-mediated clearance by the reticuloendothelial system reported in these patients.

Review of the recombinant human interferon gamma as an immunotherapeutic: Impacts of production platforms and glycosylation.

PubMed

Razaghi, Ali; Owens, Leigh; Heimann, Kirsten

2016-12-20

Human interferon gamma is a cytokine belonging to a diverse group of interferons which have a crucial immunological function against mycobacteria and a wide variety of viral infections. To date, it has been approved for treatment of chronic granulomatous disease and malignant osteopetrosis, and its application as an immunotherapeutic agent against cancer is an increasing prospect. Recombinant human interferon gamma, as a lucrative biopharmaceutical, has been engineered in different expression systems including prokaryotic, protozoan, fungal (yeasts), plant, insect and mammalian cells. Human interferon gamma is commonly expressed in Escherichia coli, marketed as ACTIMMUNE ® , however, the resulting product of the prokaryotic expression system is unglycosylated with a short half-life in the bloodstream; the purification process is tedious and makes the product costlier. Other expression systems also did not show satisfactory results in terms of yields, the biological activity of the protein or economic viability. Thus, the review aims to synthesise available information from previous studies on the production of human interferon gamma and its glycosylation patterns in different expression systems, to provide direction to future research in this field. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparison of the Z$$/\\gamma^{*}$$ + jets to $$\\gamma$$ + jets cross sections in pp collisions at $$\\sqrt{s}$$ = 8 TeV

DOE PAGES

Khachatryan, Vardan

2015-10-20

In this study, a comparison of the differential cross sections for the processes Z/γ * + jets and photon (γ)+jets is presented. The measurements are based on data collected with the CMS detector at √s = 8 TeV corresponding to an integrated luminosity of 19.7 fb –1. The differential cross sections and their ratios are presented as functions of p T. The measurements are also shown as functions of the jet multiplicity. Differential cross sections are obtained as functions of the ratio of the Z/γ* p T to the sum of all jet transverse momenta and of the ratio ofmore » the Z/γ* p T to the leading jet transverse momentum. The data are corrected for detector effects and are compared to simulations based on several QCD calculations.« less

Graphical Environment Tools for Application to Gamma-Ray Energy Tracking Arrays

DOE Office of Scientific and Technical Information (OSTI.GOV)

Todd, Richard A.; Radford, David C.

2013-12-30

Highly segmented, position-sensitive germanium detector systems are being developed for nuclear physics research where traditional electronic signal processing with mixed analog and digital function blocks would be enormously complex and costly. Future systems will be constructed using pipelined processing of high-speed digitized signals as is done in the telecommunications industry. Techniques which provide rapid algorithm and system development for future systems are desirable. This project has used digital signal processing concepts and existing graphical system design tools to develop a set of re-usable modular functions and libraries targeted for the nuclear physics community. Researchers working with complex nuclear detector arraysmore » such as the Gamma-Ray Energy Tracking Array (GRETA) have been able to construct advanced data processing algorithms for implementation in field programmable gate arrays (FPGAs) through application of these library functions using intuitive graphical interfaces.« less

Proteomic profiling of human plasma exosomes identifies PPAR{gamma} as an exosome-associated protein

DOE Office of Scientific and Technical Information (OSTI.GOV)

Looze, Christopher; Yui, David; Leung, Lester

Exosomes are nanovesicles that are released from cells as a mechanism of cell-free intercellular communication. Only a limited number of proteins have been identified from the plasma exosome proteome. Here, we developed a multi-step fractionation scheme incorporating gel exclusion chromatography, rate zonal centrifugation through continuous sucrose gradients, and high-speed centrifugation to purify exosomes from human plasma. Exosome-associated proteins were separated by SDS-PAGE and 66 proteins were identified by LC-MS/MS, which included both cellular and extracellular proteins. Furthermore, we identified and characterized peroxisome proliferator-activated receptor-{gamma} (PPAR{gamma}), a nuclear receptor that regulates adipocyte differentiation and proliferation, as well as immune and inflammatorymore » cell functions, as a novel component of plasma-derived exosomes. Given the important role of exosomes as intercellular messengers, the discovery of PPAR{gamma} as a component of human plasma exosomes identifies a potential new pathway for the paracrine transfer of nuclear receptors.« less

Assessment of Gamma-Ray-Spectra Analysis Method Utilizing the Fireworks Algorithm for Various Error Measures

DOE PAGES

Alamaniotis, Miltiadis; Tsoukalas, Lefteri H.

2018-01-01

The analysis of measured data plays a significant role in enhancing nuclear nonproliferation mainly by inferring the presence of patterns associated with special nuclear materials. Among various types of measurements, gamma-ray spectra is the widest utilized type of data in nonproliferation applications. In this paper, a method that employs the fireworks algorithm (FWA) for analyzing gamma-ray spectra aiming at detecting gamma signatures is presented. In particular, FWA is utilized to fit a set of known signatures to a measured spectrum by optimizing an objective function, where non-zero coefficients express the detected signatures. FWA is tested on a set of experimentallymore » obtained measurements optimizing various objective functions—MSE, RMSE, Theil-2, MAE, MAPE, MAP—with results exhibiting its potential in providing highly accurate and precise signature detection. Finally and furthermore, FWA is benchmarked against genetic algorithms and multiple linear regression, showing its superiority over those algorithms regarding precision with respect to MAE, MAPE, and MAP measures.« less

Primary gamma rays. [resulting from cosmic ray interaction with interstellar matter

NASA Technical Reports Server (NTRS)

Fichtel, C. E.

1974-01-01

Within this galaxy, cosmic rays reveal their presence in interstellar space and probably in source regions by their interactions with interstellar matter which lead to gamma rays with a very characteristic energy spectrum. From the study of the intensity of the high energy gamma radiation as a function of galactic longitude, it is already clear that cosmic rays are almost certainly not uniformly distributed in the galaxy and are not concentrated in the center of the galaxy. The galactic cosmic rays appear to be tied to galactic structural features, presumably by the galactic magnetic fields which are in turn held by the matter in the arm segments and the clouds. On the extragalactic scale, it is now possible to say that cosmic rays are not universal at the density seen near the earth. The diffuse celestial gamma ray spectrum that is observed presents the interesting possibility of cosmological studies and possible evidence for a residual universal cosmic ray density, which is much lower than the present galactic cosmic ray density.

Search for excited states of light and heavy flavor quarks in the $$\\gamma$$+jet final state in proton-proton collisions at $$\\sqrt{s} =$$ 13 TeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sirunyan, Albert M; et al.

A search is presented for excited quarks of light and heavy flavor that decay tomore » $$\\gamma$$+jet final states. The analysis is based on data corresponding to an integrated luminosity of 35.9 fb$$^{-1}$$ collected by the CMS experiment in proton-proton collisions at $$\\sqrt{s}=$$ 13 TeV at the LHC. A signal would appear as a resonant contribution to the invariant mass spectrum of the $$\\gamma$$+jet system, above the background expected from standard model processes. No resonant excess is found, and upper limits are set on the product of the excited quark cross section and its branching fraction as a function of its mass. These are the most stringent limits to date in the $$\\gamma$$+jet final state, and exclude excited light quarks with masses below 5.5 TeV and excited b quarks with masses below 1.8 TeV, assuming standard model couplings.« less

Finite-energy sum rules in eta photoproduction off a nucleon

DOE PAGES

Nys, Jannes; Mathieu, V.; Fernandez-Ramirez, Cesar; ...

2017-02-15

The reactionmore » $${\\gamma}N \\to {\\eta}N$$ is studied in the high-energy regime (with photon lab energies $$E_{\\gamma}^{\\textrm{lab}} > 4$$ GeV) using information from the resonance region through the use of finite-energy sum rules (FESR). We illustrate how analyticity allows one to map the t-dependence of the unknown Regge residue functions. As a result, we provide predictions for the energy dependence of the beam asymmetry at high energies.« less

Muscular exercise can cause highly pathological liver function tests in healthy men.

PubMed

Pettersson, Jonas; Hindorf, Ulf; Persson, Paula; Bengtsson, Thomas; Malmqvist, Ulf; Werkström, Viktoria; Ekelund, Mats

2008-02-01

The occurrence of idiosyncratic drug hepatotoxicity is a major problem in all phases of clinical drug development and the leading cause of postmarketing warnings and withdrawals. Physical exercise can result in transient elevations of liver function tests. There is no consensus in the literature on which forms of exercise may cause changes in liver function tests and to what extent. Weightlifting results in profound increases in liver function tests in healthy men used to moderate physical activity, not including weightlifting. Liver function tests are significantly increased for at least 7 days after weightlifting. It is important to impose relevant restrictions on heavy muscular exercise prior to and during clinical studies. To investigate the effect of intensive muscular exercise (weightlifting) on clinical chemistry parameters reflecting liver function in healthy men. Fifteen healthy men, used to moderate physical activity not including weightlifting, performed an 1 h long weightlifting programme. Blood was sampled for clinical chemistry parameters [aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LD), gamma-glutamyl transferase (gamma GT), alkaline phosphatase (ALP), bilirubin, creatine kinase (CK) and myoglobin] at repeated intervals during 7 days postexercise and at a follow-up examination 10-12 days postexercise. Five out of eight studied clinical chemistry parameters (AST, ALT, LD, CK and myoglobin) increased significantly after exercise (P < 0.01) and remained increased for at least 7 days postexercise. Bilirubin, gamma GT and ALP remained within the normal range. The liver function parameters, AST and ALT, were significantly increased for at least 7 days after the exercise. In addition, LD and, in particular, CK and myoglobin showed highly elevated levels. These findings highlight the importance of imposing restrictions on weightlifting prior to and during clinical studies. Intensive muscular exercise, e.g. weightlifting, should also be considered as a cause of asymptomatic elevations of liver function tests in daily clinical practice.

Pharmacological correction of a defect in PPAR-gamma signaling ameliorates disease severity in Cftr-deficient mice.

PubMed

Harmon, Gregory S; Dumlao, Darren S; Ng, Damian T; Barrett, Kim E; Dennis, Edward A; Dong, Hui; Glass, Christopher K

2010-03-01

Cystic fibrosis is caused by mutations in the cystic fibrosis transmembrane conductance regulator (encoded by Cftr) that impair its role as an apical chloride channel that supports bicarbonate transport. Individuals with cystic fibrosis show retained, thickened mucus that plugs airways and obstructs luminal organs as well as numerous other abnormalities that include inflammation of affected organs, alterations in lipid metabolism and insulin resistance. Here we show that colonic epithelial cells and whole lung tissue from Cftr-deficient mice show a defect in peroxisome proliferator-activated receptor-gamma (PPAR-gamma, encoded by Pparg) function that contributes to a pathological program of gene expression. Lipidomic analysis of colonic epithelial cells suggests that this defect results in part from reduced amounts of the endogenous PPAR-gamma ligand 15-keto-prostaglandin E(2) (15-keto-PGE(2)). Treatment of Cftr-deficient mice with the synthetic PPAR-gamma ligand rosiglitazone partially normalizes the altered gene expression pattern associated with Cftr deficiency and reduces disease severity. Rosiglitazone has no effect on chloride secretion in the colon, but it increases expression of the genes encoding carbonic anhydrases 4 and 2 (Car4 and Car2), increases bicarbonate secretion and reduces mucus retention. These studies reveal a reversible defect in PPAR-gamma signaling in Cftr-deficient cells that can be pharmacologically corrected to ameliorate the severity of the cystic fibrosis phenotype in mice.