537 research outputs found
Crop-based irrigation operations in the North West Frontier Province of Pakistan. Vol.II: Research approach and interpretation. Final Report
Irrigation management / Crop-based irrigation / Research / Irrigation canals / Water demand / Performance evaluation / Agricultural production / Pakistan / North West Frontier Province
Enfermedades producidas por priones en los Animales
Las encefalopatías espongiformes transmisibles (EETs) o enfermedades producidas por priones, son un grupo de enfermedades neurodegenerativas, de progresión lenta y fatales. Afectan tanto a los humanos como a los animales. Dentro de este grupo se encuentra la Encefalopatía Espongiforme Bovina (EEB), que se diagnosticó en Gran Bretaña y que posteriormente ha afectado a otros países. Esta patología ha causado gran impacto por el daño que ha provocado en la salud animal, en la economía y por su relevancia en la salud pública de estos países, al ser una enfermedad zoonótica. El agente etiológico de todas las EETs, se denomina "prión", que corresponde a la forma alterada (PrPSc) de una proteína constitutiva de la membrana celular (PrPC). La forma patológica es infectiva, capaz de producir la enfermedad, extremadamente resistente al calor y a otros métodos tradicionales de esterilización, que son efectivos contra otros patógenos. Entre las características comunes de estas patologías, se incluyen su curso con un largo periodo de incubación, el que puede durar hasta 3 años, posterior a la exposición. Los signos clínicos aparecen después de este período, los animales afectados presentan signos neurológicos progresivos y cambios morfológicos degenerativos del sistema nervioso central, que terminan con la muerte del individuo. Las principales EETs en los animales, que se describen en este trabajo son: el scrapie de ovinos y caprinos, la Encefalopatía Espongiforme Bovina (EEB), la Encefalopatía Transmisible del Visón (ETV), la Enfermedad del Desgaste Crónico (EDC) en ciervos y alces y la Encefalopatía Espongiforme Felina (EEF).
Crop-based irrigation operations in the North West Frontier Province of Pakisatn. Vol.III: Data collection procedures and data sets. Final report
Irrigation management / Crop-based irrigation / Data collection / Watercourses / Water supply / Climate / Pakistan / North West Frontier Province
A Simple Analytical Model of the Angular Momentum Transformation in Strongly Focused Light Beams
A ray-optics model is proposed to describe the vector beam transformation in
a strongly focusing optical system. In contrast to usual approaches basing on
the focused field distribution near the focal plane, we employ the transformed
beam pattern formed immediately near the exit pupil. In this cross section,
details of the output field distribution are of minor physical interest but
proper allowance is made for transformation of the incident beam polarization
state. This enables to obtain the spin and orbital angular momentum
representations which are valid everywhere in the transformed beam space.
Simple analytical results are available for the transversely homogeneous
circularly polarized incident beam limited only by the circular aperture.
Behavior of the spin and orbital angular momenta of the output beam and their
dependences on the focusing strength (aperture angle) are analyzed. The
obtained analytical results are in good qualitative and reasonable quantitative
agreement to the calculation performed for the spatially inhomogeneous Gaussian
and Laguerre-Gaussian beams. In application to Laguerre-Gaussian beams, the
model provides possibility for analyzing the angular momentum transformation in
beams already possessing some mixture of the spin and orbital angular momenta.
The model supplies efficient and physically transparent means for qualitative
analysis of the spin-to-orbital angular momentum conversion. It can be
generalized to incident beams with complicated spatial and polarization
structure.Comment: 18 pages, 5 figures. The paper has appeared as an attempt to clearly
understand transformations of the light beam polarization in the course of
strong focusing. It provides description of the optical vortex formation
after focusing a circularly polarized beam and explains why the the orbital
angular momentum emerges in the focused bea
A regional database management system—the fisheries resource information system and tools (FiRST): Its design, utility and future directions
South and Southeast Asian countries have undertaken demersal trawl surveys to measure the fisheries potential of their waters throughout the 20th century. However, ensuring full use of, and easy access to the resulting data is a challenge in developing countries. The “Fisheries Resource Information System and Tools” (FiRST) was developed through a regional collaborative effort across eight South and Southeast Asian counties to meet these needs. FiRST is a data management system for scientific trawl survey data and includes data summary and visualization tools, an analytical routine to estimate biomass, and data import/export modules. The FiRST software has also facilitated the establishment of a regional database, ‘Trawl Base’, which contains more than 20,000 hauls or stations from scientific trawl surveys in 10 countries conducted between 1926 and 1995. The regional database is an important regional resource for coastal fisheries management complementing national fisheries catch statistics
Single-molecule experiments in biological physics: methods and applications
I review single-molecule experiments (SME) in biological physics. Recent
technological developments have provided the tools to design and build
scientific instruments of high enough sensitivity and precision to manipulate
and visualize individual molecules and measure microscopic forces. Using SME it
is possible to: manipulate molecules one at a time and measure distributions
describing molecular properties; characterize the kinetics of biomolecular
reactions and; detect molecular intermediates. SME provide the additional
information about thermodynamics and kinetics of biomolecular processes. This
complements information obtained in traditional bulk assays. In SME it is also
possible to measure small energies and detect large Brownian deviations in
biomolecular reactions, thereby offering new methods and systems to scrutinize
the basic foundations of statistical mechanics. This review is written at a
very introductory level emphasizing the importance of SME to scientists
interested in knowing the common playground of ideas and the interdisciplinary
topics accessible by these techniques. The review discusses SME from an
experimental perspective, first exposing the most common experimental
methodologies and later presenting various molecular systems where such
techniques have been applied. I briefly discuss experimental techniques such as
atomic-force microscopy (AFM), laser optical tweezers (LOT), magnetic tweezers
(MT), biomembrane force probe (BFP) and single-molecule fluorescence (SMF). I
then present several applications of SME to the study of nucleic acids (DNA,
RNA and DNA condensation), proteins (protein-protein interactions, protein
folding and molecular motors). Finally, I discuss applications of SME to the
study of the nonequilibrium thermodynamics of small systems and the
experimental verification of fluctuation theorems. I conclude with a discussion
of open questions and future perspectives.Comment: Latex, 60 pages, 12 figures, Topical Review for J. Phys. C (Cond.
Matt
Resting state EEG power spectrum and functional connectivity in autism: a cross-sectional analysis
BACKGROUND: Understanding the development of the neuronal circuitry underlying autism spectrum disorder (ASD) is critical to shed light into its etiology and for the development of treatment options. Resting state EEG provides a window into spontaneous local and long-range neuronal synchronization and has been investigated in many ASD studies, but results are inconsistent. Unbiased investigation in large and comprehensive samples focusing on replicability is needed. METHODS: We quantified resting state EEG alpha peak metrics, power spectrum (PS, 2-32 Hz) and functional connectivity (FC) in 411 children, adolescents and adults (n = 212 ASD, n = 199 neurotypicals [NT], all with IQ > 75). We performed analyses in source-space using individual head models derived from the participants' MRIs. We tested for differences in mean and variance between the ASD and NT groups for both PS and FC using linear mixed effects models accounting for age, sex, IQ and site effects. Then, we used machine learning to assess whether a multivariate combination of EEG features could better separate ASD and NT participants. All analyses were embedded within a train-validation approach (70%-30% split). RESULTS: In the training dataset, we found an interaction between age and group for the reactivity to eye opening (p = .042 uncorrected), and a significant but weak multivariate ASD vs. NT classification performance for PS and FC (sensitivity 0.52-0.62, specificity 0.59-0.73). None of these findings replicated significantly in the validation dataset, although the effect size in the validation dataset overlapped with the prediction interval from the training dataset. LIMITATIONS: The statistical power to detect weak effects-of the magnitude of those found in the training dataset-in the validation dataset is small, and we cannot fully conclude on the reproducibility of the training dataset's effects. CONCLUSIONS: This suggests that PS and FC values in ASD and NT have a strong overlap, and that differences between both groups (in both mean and variance) have, at best, a small effect size. Larger studies would be needed to investigate and replicate such potential effects
Notch1 deficiency decreases hepatic lipid accumulation by induction of fatty acid oxidation
Notch signaling pathways modulate various cellular processes, including cell proliferation, differentiation, adhesion, and communication. Recent studies have demonstrated that Notch1 signaling also regulates hepatic glucose production and lipid synthesis. However, the effect of Notch1 signaling on hepatic lipid oxidation has not yet been directly investigated. To define the function of Notch1 signaling in hepatic lipid metabolism, wild type mice and Notch1 deficient antisense transgenic (NAS) mice were fed a high-fat diet. High-fat diet-fed NAS mice exhibited a marked reduction in hepatic triacylglycerol accumulation compared with wild type obese mice. The improved fatty liver was associated with an increased expression of hepatic genes involved in fatty acid oxidation. However, lipogenic genes were not differentially expressed in the NAS liver, suggesting lipolytic-specific regulatory effects by Notch1 signaling. Expression of fatty acid oxidative genes and the rate of fatty acid oxidation were also increased by inhibition of Notch1 signaling in HepG2 cells. In addition, similar regulatory effects on lipid accumulation were observed in adipocytes. Taken together, these data show that inhibition of Notch1 signaling can regulate the expression of fatty acid oxidation genes and may provide therapeutic strategies in obesity-induced hepatic steatosisopen0
Coe Genes Are Expressed in Differentiating Neurons in the Central Nervous System of Protostomes
Genes of the coe (collier/olfactory/early B-cell factor) family encode Helix-Loop-Helix transcription factors that are widely conserved in metazoans and involved in many developmental processes, neurogenesis in particular. Whereas their functions during vertebrate neural tube formation have been well documented, very little is known about their expression and role during central nervous system (CNS) development in protostomes. Here we characterized the CNS expression of coe genes in the insect Drosophila melanogaster and the polychaete annelid Platynereis dumerilii, which belong to different subgroups of protostomes and show strikingly different modes of development. In the Drosophila ventral nerve cord, we found that the Collier-expressing cells form a subpopulation of interneurons with diverse molecular identities and neurotransmitter phenotypes. We also demonstrate that collier is required for the proper differentiation of some interneurons belonging to the Eve-Lateral cluster. In Platynereis dumerilii, we cloned a single coe gene, Pdu-coe, and found that it is exclusively expressed in post mitotic neural cells. Using an original technique of in silico 3D registration, we show that Pdu-coe is co-expressed with many different neuronal markers and therefore that, like in Drosophila, its expression defines a heterogeneous population of neurons with diverse molecular identities. Our detailed characterization and comparison of coe gene expression in the CNS of two distantly-related protostomes suggest conserved roles of coe genes in neuronal differentiation in this clade. As similar roles have also been observed in vertebrates, this function was probably already established in the last common ancestor of all bilaterians
Saccade dysmetria indicates attenuated visual exploration in autism spectrum disorder
Background: Visual exploration in autism spectrum disorder (ASD) is characterized by attenuated social attention. The underlying oculomotor function during visual exploration is understudied, whereas oculomotor function during restricted viewing suggested saccade dysmetria in ASD by altered pontocerebellar motor modulation. Methods: Oculomotor function was recorded using remote eye tracking in 142 ASD participants and 142 matched neurotypical controls during free viewing of naturalistic videos with and without human content. The sample was heterogenous concerning age (6–30 years), cognitive ability (60–140 IQ), and male/female ratio (3:1). Oculomotor function was defined as saccade, fixation, and pupil-dilation features that were compared between groups in linear mixed models. Oculomotor function was investigated as ASD classifier and features were correlated with clinical measures. Results: We observed decreased saccade duration (∆M = −0.50, CI [−0.21, −0.78]) and amplitude (∆M = −0.42, CI [−0.12, −0.72]), which was independent of human video content. We observed null findings concerning fixation and pupil-dilation features (POWER =.81). Oculomotor function is a valid ASD classifier comparable to social attention concerning discriminative power. Within ASD, saccade features correlated with measures of restricted and repetitive behavior. Conclusions: We conclude saccade dysmetria as ASD oculomotor phenotype relevant to visual exploration. Decreased saccade amplitude and duration indicate spatially clustered fixations that attenuate visual exploration and emphasize endogenous over exogenous attention. We propose altered pontocerebellar motor modulation as underlying mechanism that contributes to atypical (oculo-)motor coordination and attention function in ASD
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