13,065 research outputs found
Dipole formation at metal/PTCDA interfaces: Role of the Charge Neutrality Level
The formation of a metal/PTCDA (3, 4, 9, 10-perylenetetracarboxylic
dianhydride) interface barrier is analyzed using weak-chemisorption theory. The
electronic structure of the uncoupled PTCDA molecule and of the metal surface
is calculated. Then, the induced density of interface states is obtained as a
function of these two electronic structures and the interaction between both
systems. This induced density of states is found to be large enough (even if
the metal/PTCDA interaction is weak) for the definition of a Charge Neutrality
Level for PTCDA, located 2.45 eV above the highest occupied molecular orbital.
We conclude that the metal/PTCDA interface molecular level alignment is due to
the electrostatic dipole created by the charge transfer between the two solids.Comment: 6 page
Ultra Low-Power Analog Median Filters
The design and implementation of three analog median filter topologies, whose transistors operate in the deep weak-inversion region, is described. The first topology is a differential pairs array, in which drain currents are driven into two nodes in a differential fashion, while the second topology is based on a wide range OTA, which is used to maximize the dynamic range. Finally, the third topology uses three range-extended OTAs. The proposed weak-inversion filters were designed and fabricated in ON Semiconductor 0.5 micrometer technology through MOSIS. Experimental results of three-input fabricated prototypes for all three topologies are show, where power consumptions of 90nW in the first case, and 270nW in the other two cases can be noticed. A dual power supply +/-1.5 Volts were used
Global Occurrence and Chemical Impact of Stratospheric Blue Jets Modeled With WACCM4
In this work we present the first parameterizations of the global occurrence rate and chemical influence of Blue Jets, a type of transient luminous event taking place in the stratospheric region above thunderclouds. These parameterizations are directly coupled with five different lightning parameterizations implemented in the Whole Atmosphere Community Climate Model (WACCM4). We have obtained a maximum Blue Jet global occurrence rate of about 0.9 BJ per minute. The geographical occurrence of Blue Jets is closely related to the chosen lightning parameterization. Some previously developed local chemical models of Blue Jets predicted an important influence onto the stratospheric concentration of N2O, NOx, and O3. We have used these results together with our global implementations of Blue Jets in WACCM4 to estimate their global chemical influence in the atmosphere. According to our results, Blue Jets can inject about 3.8 Tg N2O-N/year and 0.07 Tg NO-N/year near the stratosphere, where N2O-N and NO-N stand for the mass of nitrogen atoms in N2O and NO molecules, respectively. These production rates of N2O and NOx could have a direct impact on, for example, the acidity of rainwater or the greenhouse effect. We have found that Blue Jets could also slightly contribute to the depletion of stratospheric ozone. In particular, we have estimated that the maximum difference in the concentration of O3 at 30 km of altitude between simulations with and without Blue Jets can be about −5% in equatorial and polar regions. ©2019. American Geophysical Union. All Rights Reserved.This work was supported by the Spanish Ministry of Science and Innovation, MINECO under projects and ESP2017-86263-C4-4-R and by the EU through the H2020 Science and Innovation with Thunderstorms (SAINT) project (Ref. 722337) and the FEDER program. Authors F.J.P.I and F.J.G.V acknowledge financial support from the State Agency for Research of the Spanish MCIU through the >Center of Excellence Severo Ochoa> award for the Instituto de Astrofisica de Andalucia(SEV-2017-0709). The National Center for Atmospheric Research is sponsored by the National Science Foundation. The CESM project is supported by the National Science Foundation and the Office of Science (BER) of the U.S. Department of Energy. Computing resources were provided by the Climate Simulation Laboratory at NCAR's Computational and Information Systems Laboratory (CISL), sponsored by the National Science Foundation and other agencies. F. J. P.-I. acknowledges a PhD research contract, code BES-2014-069567. F. J. G.-V. acknowledges support from the Spanish Ministry of Education and Culture under the Salvador de Madariaga program PRX17/00078.Peer Reviewe
Status of QCD
I have been asked to discuss the status of QCD. It seems to me that there are
three main points to be made about the present status of QCD: QCD is
right, and we can do many beautiful things with it. There are several
important concrete problems that lie just beyond the edge of our current
understanding. There are some foundational issues in QCD, and some
recent developments, that may point toward entirely new directions. These
points will, I believe, emerge quite clearly from the following more detailed
discussion. The discussion will be in three parts. I'll first discuss
elementary processes, then more complicated processes, and then finally
foundational issues.Comment: 28 pages, use Phyzzx, figures available by FAX or mail on request,
IASSNS-HEP-93/6
Cambio de uso de suelo e implicaciones socioeconómicas en un área mazahua del altiplano mexicano
Se analizan los cambios de uso del suelo entre 2000 y 2010 de la región mazahua del Estado de México y sus implicaciones socioeconómicas. El estudio se sustenta en la geografía socioeconómica de Bonfil (1996) y los procesos de cambio de uso del suelo de Fernández y Prados (2010) para evaluar los cambios de uso del suelo. Se utilizó clasificación supervisada de máxima probabilidad y datos socioeconómicos y demográficos. Los resultados de análisis de imágenes fueron verificados mediante recorridos en campo. Los cambios pueden deberse al crecimiento poblacional, en los modos de vida y su consecuente demanda de alimentos y viviendas.Se analizan los cambios de uso del suelo entre 2000 y 2010 de la región mazahua del Estado de México y sus implicaciones socioeconómicas. El estudio se sustenta en la geografía socioeconómica de Bonfil (1996) y los procesos de cambio de uso del suelo de Fernández y Prados (2010) para evaluar los cambios de uso del suelo. Se utilizó clasificación supervisada de máxima probabilidad y datos socioeconómicos y demográficos. Los resultados de análisis de imágenes fueron verificados mediante recorridos en campo. Los cambios pueden deberse al crecimiento poblacional, en los modos de vida y su consecuente demanda de alimentos y viviendas
Na+/K+-ATPase is a new interacting partner for the neuronal glycine transporter GlyT2 that downregulates its expression in vitro and in vivo
The neuronal glycine transporter GlyT2 plays a fundamental role in the glycinergic neurotransmission by recycling the neurotransmitter to the presynaptic terminal. GlyT2 is the main supplier of glycine for vesicle refilling, a process that is absolutely necessary to preserve quantal glycine content in synaptic vesicles. Alterations in GlyT2 activity modify glycinergic neurotransmission and may underlie several neuromuscular disorders, such as hyperekplexia, myoclonus, dystonia, and epilepsy. Indeed, mutations in the gene encoding GlyT2 are the main presynaptic cause of hyperekplexia in humans and produce congenital muscular dystonia type 2 (CMD2) in Belgian Blue cattle. GlyT2 function is strictly coupled to the sodium electrochemical gradient actively generated by the Na+/K+-ATPase (NKA). GlyT2 cotransports 3Na+/Cl-/glycine generating large rises of Na+ inside the presynaptic terminal that must be efficiently reduced by the NKA to preserve Na+ homeostasis. In this work, we have used high-throughput mass spectrometry to identify proteins interacting with GlyT2 in the CNS. NKA was detected as a putative candidate and through reciprocal coimmunoprecipitations and immunocytochemistry analyses the association between GlyT2 and NKA was confirmed. NKA mainly interacts with the raft-associated active pool of GlyT2, and low and high levels of the specific NKA ligand ouabain modulate the endocytosis and total expression of GlyT2 in neurons. The ouabain-mediated downregulation of GlyT2 also occurs in vivo in two different systems: zebrafish embryos and adult rats, indicating that this NKA-mediated regulatory mechanism is evolutionarily conserved and may play a relevant role in the physiological control of inhibitory glycinergic neurotransmission
Self-textured ZnO via AACVD of alkyl alkoxides: a solution-based seed-less route towards optoelectronic-grade coatings
Carbon-free, crystalline and transparent (002)-oriented ZnO films with thickness below 200 nm were deposited at 350 °C on plain glass via AACVD. ZnO films restricted to PVD-growth are achievable through a fast, cost-effective and scalable methodology
Acute stress response in gilthead sea bream (Sparus aurata L.) is time-of-day dependent: Physiological and oxidative stress indicators
Since fish show daily rhythms in most physiological functions, it should not be surprising that stressors may have different effects depending on the timing of exposure. In this study, we investigated the influence of time of day on the stress responses, at both physiological and cellular levels, in gilthead sea bream (Sparus aurataL.) submitted to air exposure for 30 s and then returned to their tank. One hour after air exposure, blood, hypothalamus and liver samples were taken. Six fish per experimental group (control and stressed) were sampled every 4 h during a 24-h cycle. Fish were fed in the middle of the light cycle (ML) and locomotor activity rhythms were recorded using infrared photocells to determine their daily activity pattern of behaviour, which showed a peak around feeding time in all fish. In the control group, cortisol levels did not show daily rhythmicity, whereas in the stressed fish, a daily rhythm of plasma cortisol was observed, being the average values higher than in the control group, with increased differences during the dark phase. Blood glucose showed daily rhythmicity in the control group but not in the stressed one which also showed higher values at all sampling points. In the hypothalamus of control fish, a daily rhythm ofcorticotropin-releasing hormone(crh) gene expression was observed, with the acrophase at the beginning of the light phase. However, in the stressed fish, this rhythm was abolished. The expression ofcrh-binding protein(crhbp) showed a peak at the end of the dark phase in the control group, whereas in the stressed sea bream, this peak was found at ML. Regarding hepatic gene expression of oxidative stress biomarkers: (i)cytochrome c oxidase 4showed daily rhythmicity in both control and stressed fish, with the acrophases located around ML, (ii)peroxiredoxin(prdx) 3 and5(prdx5) only presented daily rhythmicity of expression in the stressed fish, with the acrophase located at the beginning of the light cycle and (iii)uncoupling protein 1showed significant differences between sampling points only in the control group, with significantly higher expression at the beginning of the dark phase. Taken together, these results indicate that stress response in gilthead sea bream is time-dependent as cortisol level rose higher at night, and that different rhythmic mechanisms interplay in the control of neuroendocrine and cellular stress responses
Mutation Analysis in Regulator DNA-Binding Regions for Antimicrobial Efflux Pumps in 17,000 Pseudomonas aeruginosa Genomes
Mutations leading to upregulation of efflux pumps can produce multiple drug resistance in the pathogen Pseudomonas aeruginosa. Changes in their DNA binding regions, i.e., palindromic operators, can compromise pump depression and subsequently enhance resistance against several antibacterials and biocides. Here, we have identified (pseudo)palindromic repeats close to promoters of genes encoding 13 core drug-efflux pumps of P. aeruginosa. This framework was applied to detect mutations in these repeats in 17,292 genomes. Eighty-nine percent of isolates carried at least one mutation. Eight binary genetic properties potentially related to expression were calculated for mutations. These included palindromicity reduction, mutation type, positioning within the repeat and DNA-bending shift. High-risk ST298, ST308 and ST357 clones commonly carried four conserved mutations while ST175 and the cystic fibrosis-linked ST649 clones showed none. Remarkably, a T-to-C transition in the fourth position of the upstream repeat for mexEF-oprN was nearly exclusive of the high-risk ST111 clone. Other mutations were associated with high-risk sublineages using sample geotemporal metadata. Moreover, 1.5% of isolates carried five or more mutations suggesting they undergo an alternative program for regulation of their effluxome. Overall, P. aeruginosa shows a wide range of operator mutations with a potential effect on efflux pump expression and antibiotic resistance.This research was funded by Acción Estratégica en Salud from the ISCIII, grant MPY 509/19. This research was also supported by Personalized and Precision Medicine grant from the Instituto de Salud Carlos III (MePRAM Project, PMP22/00092), Instituto de Salud Carlos III, Ministerio de Ciencia e Innovación and Unión Europea-NextGenerationEU.S
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