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The objective of this study was to develop new standardized alcohol-associated cues and assess their effects on brain activation with functional magnetic resonance imaging (fMRI). Pictures of alcoholic and neutral beverages and affectively neutral pictures were presented to 44 abstinent alcoholics and 37 age-matched healthy control subjects. We assessed the skin conductance response, and the elicited arousal and valence. Alcoholics and control subjects did not differ in arousal, valence or skin conductance response evoked by alcohol-associated and affectively neutral stimuli, while nonalcoholic beverages were rated as more unpleasant and arousing by alcoholics compared with control subjects. In the fMRI pilot study, alcohol and abstract pictures were presented to six abstinent alcoholics and induced a significant activation of brain areas associated with visual emotional processes such as the fusiform gyrus, parts of the brain reward system (basal ganglia and orbitofrontal gyrus) and further brain regions in the frontal and parietal cortices associated with the attention network. These observations suggest that standardized pictures of alcoholic beverages can be used to assess brain circuits involved in the processing and evaluation of alcohol cues.
Gaia DR2 was released in April 2018 and contains a photometric catalogue of more than 1 billion sources. This release contains colour information in the form of integrated BP and RP photometry in addition to the latest G-band photometry. The level of uncertainty can be as good as 2 mmag with some residual systematics at the 10 mmag level. The addition of colour information greatly enhances the value of the photometric data for the scientific community. A high level overview of the photometric processing, with a focus on the improvements with respect to Gaia DR1, was given. The definition of the Gaia photometric system, a crucial part of the calibration of the photometry, was also explained. Finally, some of the photometric improvements expected for the next data release were described.
Enhanced acquisition and delayed extinction of fear conditioning are viewed as major determinants of anxiety disorders, which are often characterized by a dysfunctional hypothalamic–pituitary–adrenal (HPA) axis.
In this study we employed cued fear conditioning in two independent samples of healthy subjects (sample 1: n=60, sample 2: n=52). Two graphical shapes served as conditioned stimuli and painful electrical stimulation as the unconditioned stimulus. In addition, guided by findings from published animal studies on HPA axis-related genes in fear conditioning, we examined variants of the glucocorticoid receptor and corticotropin-releasing hormone receptor 1 genes.
Variation in these genes showed enhanced amygdala activation during the acquisition and reduced prefrontal activation during the extinction of fear as well as altered amygdala–prefrontal connectivity.
This is the first demonstration of the involvement of genes related to the HPA axis in human fear conditioning.
We study the quasifinear relaxation of an aperiodic instability, namely the instability caused by the temperature anisotropy of a collisionless electron plasma in the absence of an external magnetic field. We give a detailed description of the relaxation process and we examine the validity of the quasilinear theory (existence of separate time scales, quasilinearity of the particles' orbits).
Comparative and functional fungal genomics
R. A. Dean, Center for Integrated Fungal Research Department of Plant Pathology 1200 Partners Building II Box 7251 North Carolina State University Raleigh NC 27695 USA,
T. Mitchell, North Carolina State University Department of Plant Pathology Campus Box 7251 Raleigh NC 27695–7251 USA,
R. Kulkarni, RTI 3040 Cornwallis Road Research Triangle Park NC 27709 USA,
N. Donofrio, North Carolina State University Department of Plant Pathology Campus Box 7251 Raleigh NC 27695–7251 USA,
A. Powell, North Carolina State University Department of Plant Pathology Campus Box 7251 Raleigh NC 27695–7251 USA,
Y. Y. Oh, North Carolina State University Department of Plant Pathology Campus Box 7251 Raleigh NC 27695–7251 USA,
S. Diener, North Carolina State University Department of Plant Pathology Campus Box 7253 Raleigh NC 27695–7253 USA,
H. Pan, RTI 3040 Cornwallis Road Research Triangle Park NC 27709 USA,
D. Brown, North Carolina State University Department of Plant Pathology Campus Box 7251 Raleigh NC 27695–7251 USA,
J. Deng, North Carolina State University Department of Plant Pathology Campus Box 7251 Raleigh NC 27695–7251 USA,
I. Carbone, North Carolina State University Department of Plant Pathology Campus Box 7244 Raleigh NC 27695–7244 USA,
D. J. Ebbole, Department of Plant Pathology and Microbiology Peterson Building Rm 120 MS# 2132 Texas A&M University College Station TX 77843–2132 USA,
M. Thon, Department of Computer Science 320C Peterson Building MS# 2132 Texas A&M University College Station TX 77843–2132 USA,
M. L. Farman, Department of Plant Pathology University of Kentucky 1405 Veterans Drive Lexington KY 40546–0312 USA,
M. J. Orbach, Department of Plant Pathology University of Arizona Forbes Room 105 PO Box 210036 Tucson AZ 85721–0036 USA,
C. Soderlund, Director of Bioinformatics Department of Plant Science 303 Forbes Building Tucson AZ 85721 USA,
J-R. Xu, Department of Botany and Plant Pathology 915 West State Street Purdue University West Lafayette IN 47906 USA,
Y-H. Lee, Seoul National University School of Agricultural Biotechnology Suwon 441–744 Korea,
N. J. Talbot, Department of Biological Sciences University of Exeter Hatherly Laboratories Prince of Wales Road Exeter EX4 4PS UK,
S. Coughlan, Agilent Technologies Inc. Little Falls Site 2850 Centerville Road Wilmington DE 19808 USA,
J. E. Galagan, The Broad Institute Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge MA 02139–4307 USA,
B. W. Birren, The Broad Institute Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge MA 02139–4307 USA
Rice blast disease, caused by the filamentous fungus Magnaporthe grisea, is a serious and recurrent problem in all rice-growing regions of the world (Talbot, 2003; Valent & Chumley, 1991). It is estimated that each year enough rice is destroyed by rice blast disease to feed 60 million people. Control of this disease is difficult; new host-specific forms develop quickly to overcome host resistance and chemical control is typically not cost effective (Ou, 1987). Infections occur when fungal spores land and attach themselves to leaves using a special adhesive released from the tip of each spore (Hamer et al., 1988). The germinating spore develops an appressorium, a specialized infection cell, which generates enormous turgor pressure – up to 8 MPa – that ruptures the leaf cuticle allowing invasion of the underlying leaf tissue (de Jong et al., 1997; Dean, 1997). Subsequent colonization of the leaf produces disease lesions from which the fungus sporulates and spreads to new plants. When rice blast infects young rice seedlings, whole plants often die, while spread of the disease to the stems, nodes or panicle of older plants results in nearly total loss of the rice grain. Recent reports have further shown that the fungus has the capacity to infect plant roots (Sesma & Osbourn, 2004). Different host-limited forms of Magnaporthe also infect a broad range of grass species including wheat, barley and millet.
El objetivo de este estudio era desarrollar nuevas claves estandarizadas asociadas al alcohol y evaluar sus efectos sobre la activación cerebral con resonancia magnética nuclear funcional (RMNf). Se presentaron imágenes de bebidas alcohólicas y neutrales e imágenes neutrales afectivamente a 44 alcohólicos abstinentes y 37 sujetos de control sanos emparejados por la edad. Evaluamos la respuesta de conductancia de la piel, y la activación y la valencia provocadas. Los alcohólicos y los sujetos de control no difirieron en la activación, la valencia o la respuesta de conductancia de la piel evocadas por los estímulos asociados con el alcohol y los neutrales afectivamente, mientras que los alcohólicos evaluaron las bebidas no alcohólicas como más desagradables y activadoras, comparado con los sujetos de control. En el estudio piloto de RMNf, se presentaron imágenes relacionadas con el alcohol y abstractas a seis alcohólicos abstinentes, e indujeron una activación significativa de las áreas cerebrales asociadas con los procesos emocionales visuales, como el giro fusiforme, partes del sistema de recompensa del cerebro (ganglios basales y giro orbitofrontal) y otras regiones cerebrales en las cortezas frontal y parietal asociadas con la red de atención. Estas observaciones indican que se pueden utilizar imágenes estandarizadas de bebidas alcohólicas para evaluar los circuitos cerebrales implicados en el procesamiento y la evaluación de las claves de alcohol.
We report on efficient electronic energy transfer from excitons confined in silicon (Si) nanocrystals to molecular oxygen (MO). The remarkable photosensitizing properties of Si nanocrystal assemblies result from a broad energy spectrum of photoexcited excitons, a long triplet exciton lifetime and a highly developed surface area. Quenching of photoluminescence (PL) of Si nanocrystals by MO physisorbed on their surface is found to be most efficient when the energy of excitons coincides with the triplet-singlet splitting energy of oxygen molecules. Spectroscopic analysis of the quenched PL spectrum evidences that energy transfer is accompanied by multi-phonon emission. From time-resolved measurements the characteristic time of energy transfer is found to be in the range of microseconds. The dependence of PL quenching efficiency on the surface termination of nanocrystals is consistent with short-range resonant electron exchange mechanism of energy transfer. The energy transfer to oxygen molecules in the gaseous phase at elevated temperatures is demonstrated.
Anisotropic nanostructuring of bulk silicon (Si) leads to a significant optical anisotropy of single porous silicon (PSi) layers. A variation of the etching current in time allows a controlled modification of the porosity along the growth direction and therefore a three-dimensional variation of the refractive index (in plane an in depth). This technique can be important for photonic applications since it is the basis of a development of a variety of novel, polarization sensitive, silicon-based optical devices: retarders, dichroic Bragg Reflectors, dichroic microcavities and Si based polarizers.
We report on the photosensitizing properties of optically excited Silicon (Si) nanocrystal assemblies that are employed for an efficient generation of singlet oxygen. Spin triplet state excitons confined in Si nanocrystals transfer their energy to molecular oxygen (MO) adsorbed on the nanocrystal surface. This process results in a strong suppression of the photoluminescence (PL) from the Si nanocrystal assembly and in the excitation of MO from the triplet ground state to singlet excited states. The high efficiency of the energy transfer if favored by a broad energy spectrum of photoexcited excitons, a long triplet exciton lifetime and a highly developed surface area of the nanocrystal assembly. Due to the specifics of the coupled system Si nanocrystal – oxygen molecule all relevant physical parameters describing the photosensitization process are accessible experimentally. This includes the role of resonant and phonon-assisted energy transfer, the dynamics of energy transfer, and its mechanism.
We present optical and microstructural characterization of nanocrystalline silicon superlattices (nc-Si SLs). Our samples have better than 5 % Si nanocrystal size distribution and a long range order along the direction of growth provided by periodically alternating layers of Si nanocrystals and SiO2. Flat and chemically abrupt nc-Si/SiO2 interfaces with a roughness of < 4Å are confirmed by transmission electron microscopy (TEM), Auger elemental microanalysis, X-ray small angle reflection, and low-frequency Raman scattering. Photoluminescence (PL) in our structures has been studied in details including time-resolved and steady-state PL spectroscopy in a wide range of temperature, excitation wavelength and power. Resonantly excited PL spectra show phonon steps proving that the PL originates in Si nanocrystals. Electrical measurements show signature of phonon-assisted tunneling proving low defect density nc-Si/SiO2 interface.
Fourier transform infrared spectroscopy is used to determine the time evolution of oxygen incorporation onto the surface of silicon nanocrystals. Oxygen concentrations up to one monolayer are investigated. The temporal progress of surface oxidation of Si nanocrystals in porous silicon shows a linear dependence on the square root of the oxidation time. This is similar to the oxidation of bulk Si and mesoporous silicon.
A pulsed, high-power TEA CO2 laser with Unes in the region from 9.2 to 10.6 μm has been used to irradiate luminescent porous Si samples. The IR laser pulses heat the sample on a time scale much shorter than the PL decay time which is at 300 K for the PL at 1.65 eV in the order of tenth of μs. One IR pulse serves to increase the temperature of the luminescing particles in ∼2 μs up to 100°C. This increase of temperature leads to a efficient reduction of the photoluminescence (PL) intensity. However, the PL decay times are almost not affected by the heating pulse. Based on this measurement a picture of the recombination statistics that takes account of the granular Nature of the material is developed.
We demonstrate experimentally that linear polarization of porous Si photoluminescence depends significantly on the excitation geometry and describe this effect within the framework of a dielectric model in which porous Si is considered as an aggregate of slightly deformed, elongated and flattened, dielectric elliptical Si nanocrystals with preferred orientation in the  direction. The theoretical best-fit analysis of the experimental data allows us to get certain information concerning the shapes and orientation of the ellipsoids.
We report on conductance and cyclotron resonance (CR) experiments on GaN epitaxial films grown by the OMVPE and HVPE techniques. From a precise determination of the electron effective mass the donor binding energy in the effective mass approximation (EMT) is calculated. We obtain 31.7 meV. The transport experiments on the HVPE films show that the conductance is thermally activated with an activation energy of 15 meV in contrast to the OMVPE films which showed temperature independent conductivity for temperatures between 4 and 100 K.
A pulsed, high-power TEA CO2 laser with lines in the region from 9.2 to 10.6 μm has been used to irradiate luminescent porous Si samples. The visible luminescence quenches and then recovers to its initial value on a time scale of one hour. It is found that the quenching is efficient when the IR wavelength is within the Si-O absorption band. We suggest that the resonant excitation of the Si-O bonds results in a metastable reconfiguration of the oxygen together with the creation of dangling bonds. These non-radiative centers are responsible for the PL quenching.
This review describes some characteristics of patients with cerebellar lesions, including limb movements, changes in motor planning and disturbances in time-dependent perception. The delay in movement initiation can be explained by a delay in onset of movement-related discharge of neurons in motor cortex. Disorders of movement termination (hypermetria) are accompanied by asymmetric velocity profiles and by prolonged agonist and delayed antagonist EMG activity necessary to brake the movement. During complex movements in three-dimensional space, the cerebellum contributes to timing between single components of a movement, scales the size of muscular action, and coordinates the sequence of agonists and antagonists. The basic structure of motor programs is not generated exclusively within the cerebellum and patients with cerebellar lesions can use precuing information to improve their motor performance. Time-dependent perception in the auditory and visual domains are disturbed in patients with cerebellar lesions.
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