442 research outputs found
Embedding media for cryomicrotomy: an applicative reappraisal
No full textWe reassess here the formulation of cryoembedding media in connection with recent developments in commercial cryomicrotomes. Water-based solutions of polyvinyl alcohols were our starting media, and each of 2 different polymers (56-98, MW ∼195000; and 6-98, MW ∼47000) showed a critical concentration for optimum sectioning. At higher or lower polymer concentrations, wrinkles and folds became apparent in tissue areas of sections, or in the sectioned embedding medium areas between tissues, respectively. Addition of polyethylene glycol (MW 380-420) further facilitated and improved sectioning, resulting in frozen tissue blocks that cut well in the 2 to 100 μm range and further, using disposable blades throughout. Applying a wide temperature differential between tissue specimen (-11°C to -13°C) and cutting knife (-33°C to -35°C), serial adjacent sections were reproducibly obtained at a 2-μm setting, singly or in short ribbons. Embedding media of low and high viscosity were obtained, depending on the polyvinyl alcohol polymer used, and could be applied sequentially for tissue infiltration followed by embedding with precise sample orientation. When required, media were made semisolid by addition of carboxymethylcellulose
Equipment testing and tuning: the cold-knife cryomicrotome microm HM-560
No full textA major innovative feature of the Microm HM-560 cryomicrotome is the independent control of specimen and knife temperatures. We used such equipment with a variety of tissues, and fixation and freezing procedures. High-quality sectioning was reproducibly obtained using 1) a low temperature setting for the sectioning blade ("cold knife," about -33°C); 2) a comparatively high temperature for the specimen, and 3) a suitable mounting medium, which would remain solid up to about 0°C. Specimen temperature was set between -8° and -15°C for 4-μm sectioning, higher temperatures (-1° to -8°C) being appropriate when cutting at 10 to 20 μm. Under such conditions, disposable blades were effective throughout, while a modified antiroll plate profile further enhanced usability. After intensive use for almost 3 years, by more than 15 different users, the cryomicrotome is in excellent working order
A giant pancreatic pseudocyst in a patient with HIV infection.
No full textThis article describes the first case of a giant pancreatic pseudocyst in a 48-year-old man with HIV infection under combination antiretroviral therapy. The patient presented with an abdominal mass involving the epigastrium, left hypochondrium, and left flank. An enhanced abdominal computed tomography (CT) scan showed a well-defined cyst of 21 cm in diameter, with a liquid content that dislocated adjacent viscera. Microbiological and cytological tests on fluid were negative, confirming diagnosis of pancreatic pseudocyst. The CT-guided percutaneous drainage was carried out and the patient's clinical condition gradually improved. © The Author(s) 2012
GV and GW invariants via the enhanced movable cone
No full textGiven any smooth germ of a threefold flopping contraction, we first give a combinatorial characterisation of which Gopakumar-Vafa (GV) invariants are non-zero, by prescribing multiplicities to the walls in the movable cone. On the Gromov-Witten (GW) side, this allows us to describe, and even draw, the critical locus of the associated quantum potential. We prove that the critical locus is the infinite hyperplane arrangement of Iyama and the second author, and moreover that the quantum potential can be reconstructed from a finite fundamental domain. We then iterate, obtaining a combinatorial description of the matrix which controls the transformation of the non-zero GV invariants under a flop. There are three main ingredients and applications: (1) a construction of flops from simultaneous resolution via cosets, which describes how the dual graph changes, (2) a closed formula which describes the change in dimension of the contraction algebra under flop, and (3) a direct and explicit isomorphism between quantum cohomologies of different crepant resolutions, giving a Coxeter-style, visual proof of the Crepant Transformation Conjecture for isolated cDV singularities.32 pages. Comments welcome. v2: minor changes. Final version to appear in Modul
GV/cm scale laser-magnetic resonant acceleration in vacuum
No full textResonant acceleration of electrons by a laser in the background of an extra longitudinal magnetic field is investigated analytically and numerically. The resonant condition is independent of laser intensity, and when satisfied, the energy gain is proportional to a(0)(2) and the square of phase difference. This process is mainly limited by the magnitude and spatial size of the extra magnetic field. Under the laboratory conditions, simulation results show that a monoenergetic and collimated electron bunch can still be obtained in similar to GV/cm scale, which sheds a light on the vacuum table-top laser-driven electron accelerators.National Key Programme for S&TResearch and Development [2016YFA0401100]; China Academy of Engineering Physics Foundation [2014A0102003]SCI(E)ARTICLE3520-5273
On right K-completeness of the fine quasi-uniformity
No full text[EN] We investigate right K-components of the fine quasi-uniformity. It follows from our results the somewhat surprising fact that if (X,T) is a topological space condensable onto a quasi-metric space whose conjugate is Hausdorff, then any right K-Cauchy filter F on the fine quasi-uniformity of (X,T) is trivial (i.e. there is an x €X such that {x} generates F.The second author acknowledges the support of the Conselleria de Educació i Ciencia, Generalitat Valenciana, gran GV-2223/94Perez, M.; Romaguera, S. (1996). On right K-completeness of the fine quasi-uniformity. Questions and Answers in General Topology. 14(2):245-249. https://riunet.upv.es/handle/10251/107319S24524914
Precision Measurement of the Helium Flux in Primary Cosmic Rays of Rigidities 1.9 GV to 3 TV with the Alpha Magnetic Spectrometer on the International Space Station
No full textKnowledge of the precise rigidity dependence of the helium flux is important in understanding the origin, acceleration, and propagation of cosmic rays. A precise measurement of the helium flux in primary cosmic rays with rigidity (momentum/charge) from 1.9 GV to 3 TV based on 50 million events is presented and compared to the proton flux. The detailed variation with rigidity of the helium flux spectral index is presented for the first time. The spectral index progressively hardens at rigidities larger than 100 GV. The rigidity dependence of the helium flux spectral index is similar to that of the proton spectral index though the magnitudes are different. Remarkably, the spectral index of the proton to helium flux ratio increases with rigidity up to 45 GV and then becomes constant; the flux ratio above 45 GV is well described by a single power law. © 2015 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the «http://creativecommons.org/licenses/by/3.0/» Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI
Photosynthesis down-regulation precedes carbohydrate accumulation under sink limitation in Citrus
No full textPhotosynthesis down-regulation due to an imbalance between sources and sinks in Citrus leaves could be mediated by excessive accumulation of carbohydrates. However, there is limited understanding of the physiological role of soluble and insoluble carbohydrates in photosynthesis regulation and the elements triggering the down-regulation process. In this work, the role of non-structural carbohydrates in the regulation of photosynthesis under a broad spectrum of source-sink relationships has been investigated in the Salustiana sweet orange. Soluble sugar and starch accumulation in leaves, induced by girdling experiments, did not induce down-regulation of the photosynthetic rate in the presence of sinks (fruits). The leaf-to-fruit ratio did not modulate photosynthesis but allocation of photoassimilates to the fruits. The lack of strong sink activity led to a decrease in the photosynthetic rate and starch accumulation in leaves. However, photosynthesis down-regulation due to an excess of total soluble sugars or starch was discarded because photosynthesis and stomatal conductance reduction occurred prior to any significant accumulation of these carbohydrates. Gas exchange and fluorescence parameters suggested biochemical limitations to photosynthesis. In addition, the expression of carbon metabolism-related genes was altered within 24 h when strong sinks were removed. Sucrose synthesis and export genes were inhibited, whereas the expression of ADP-glucose pyrophosphorylase was increased to cope with the excess of assimilates. In conclusion, changes in starch and soluble sugar turnover, but not sugar content per se, could provide the signal for photosynthesis regulation. In these conditions, non-stomatal limitations strongly inhibited the photosynthetic rate prior to any significant increase in carbohydrate levels. © The Author 2011. Published by Oxford University Press. All rights reserved.This work was supported by the Conselleria de Cultura, Educacio i Esport de la Generalitat Valenciana [GV/2007/213 and GV/2009/034].González Nebauer, S.; Renau Morata, B.; Guardiola, JL.; Molina Romero, RV. (2011). Photosynthesis down-regulation precedes carbohydrate accumulation under sink limitation in Citrus. Tree Physiology. 31(2):169-177. doi:10.1093/treephys/tpq103S16917731
TUD-GV Dataset for Floating Litter Detection
No full text<p>This dataset contains the data used for the publication of "Jia T, Vallendar AJ, de Vries R, Kapelan Z and Taormina R (2023) Advancing deep learning-based detection of floating litter using a novel open dataset. <i>Front. Water</i> 5:1298465. doi: 10.3389/frwa.2023.1298465"</p><p>The large-scale "TU Delft - Green Village" (TUD-GV) dataset is for detecting floating litter with computer vision. We created this dataset from experiments conducted during 10 days in February and April 2021 in a small drainage canal at The Green Village — a field lab facility in the TU Delft Campus, the Netherlands. We captured data using two action cameras (GoPro HERO4 and GoPro MAX 360) and a phone (Huawei P30 Pro) mounted on four different locations on a bridge. All devices recorded videos with a resolution of 1080p, a linear field of view, and a FPS (frame per second) of 24 (for the action cameras) or 30 (for the phone).</p><p>This dataset consists of 9,473 RGB images. We manually labeled the images in the TUD-GV dataset into four classes: <i>no litter</i> (0 items), <i>little litter</i> (1-2 items), <i>moderate litter</i> (3-5 items), and <i>lots of litter</i> (6-10 items) according to the number of litter items in images.</p><p>This dataset is stored in the ZIP file contain 77 directories and the TUD-GV.xls file. Each of these directories contain four class label directories, and each label directory contains JPG images. The TUD-GV.xls file contains the detailed information of images in 77 directories, including collecting date, collecting time, device, device location (in a bridge), device degree, device height, weather conditions, litter source, the number of images per class, and the number of images in total.</p><p>If you use this dataset for a publication, please cite the paper. Here is a BibTeX entry:</p><p>@article{jia2023advancing,
title={Advancing Deep Learning-based Detection of Floating Litter using a Novel Open Dataset},
author={Jia, Tianlong and Vallendar, Andre Jehan and de Vries, Rinze and Kapelan, Zoran and Taormina, Riccardo},
journal={Frontiers in Water},
volume={5},
pages={1298465},
publisher={Frontiers},
year={2023}
}</p>
Manufactured homeworking in the Vega Baja del Segura (Alicante): Origin and development in an agricultural town
No full textEl trabajo industrial a domicilio ha cobrado una importancia considerable a raíz de la
crisis industrial de la década de los setenta y del proceso de descentralización productiva
derivada de la misma. Esta nueva forma de actividad que afectó en un primer momento
a las periferias urbanas, se ha expandido en el medio rural. El artículo analiza el grado de
implantación entre las familias de un municipio de la Vega Baja del Segura en la
provincia de Alicante. La localidad, que surgió dependiendo de los núcleos industriales
tradicionales del corredor del Vinalopó, se ha convertido en la actualidad en un centro
difusor de este tipo de trabajo.Informal manufactured home-work has become very important due to the industrial
crisis in the 1970’s and to the productive decentralization process arising from it. This
new activity was developed firstly in urban suburbs and later in rural areas.
The article analyzes how this domestic-work has grown among families in a town in
the province of Alicante. The town at the beginning linked completely to the greater
industrial centers (the route of Vinalopo) is at present one of the centers of the network at
the South of the province.Este trabajo forma parte de un estudio más amplio que bajo el título: «El Trabajo a domicilio en
Alicante: las estrategias de adaptación de los grupos domésticos», se está realizando bajo la dirección de
A. Melis Maynar, en el Dpto. de Humanidades Contemporáneas (Área de Antropología), dentro de la Ayuda
a Grupos Precompetitivos de la Universidad de Alicante. La investigación forma parte, además, del Proyecto
«Recursos humanos e industrialización en la Comunidad Valenciana (1860-1994)», Programa de Investigación
Científica y Desarrollo Tecnológico de la Generalitat Valenciana, GV-2401/9
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