20,941 research outputs found
Toroidal transformers procedure 902.66-01 Final report
Qualification tests of multi-secondary toroidal transformers and open-construction ratio toroidal transformer
Catalase and peroxiredoxin 5 protect Xenopus embryos against alcohol-induced ocular anomalies
published_or_final_versio
Abnormally high content of free glucosamine residues identified in a preparation of commercially available porcine intestinal heparan sulfate
Heparan sulfate (HS) polysaccharides are ubiquitous in animal tissues as components of proteoglycans, and they participate in many important biological processes. HS carbohydrate chains are complex and can contain rare structural components such as N-unsubstituted glucosamine (GlcN). Commercially available HS preparations have been invaluable in many types of research activities. In the course of preparing microarrays to include probes derived from HS oligosaccharides, we found an unusually high content of GlcN residue in a recently purchased batch of porcine intestinal mucosal HS. Composition and sequence analysis by mass spectrometry of the oligosaccharides obtained after heparin lyase III digestion of the polysaccharide indicated two and three GlcN in the tetrasaccharide and hexasaccharide fractions, respectively. (1)H NMR of the intact polysaccharide showed that this unusual batch differed strikingly from other HS preparations obtained from bovine kidney and porcine intestine. The very high content of GlcN (30%) and low content of GlcNAc (4.2%) determined by disaccharide composition analysis indicated that N-deacetylation and/or N-desulfation may have taken place. HS is widely used by the scientific community to investigate HS structures and activities. Great care has to be taken in drawing conclusions from investigations of structural features of HS and specificities of HS interaction with proteins when commercial HS is used without further analysis. Pending the availability of a validated commercial HS reference preparation, our data may be useful to members of the scientific community who have used the present preparation in their studies
Wettability conundrum: Discrepancies of soft contact lens performance in vitro and in vivo
The recognition and appreciation of soft contact lenses as simple, efficient and aesthetically gratifying vision-correction devices is ever growing, especially among younger population. Stable thin tear film uniformly spread over corrective lens surface is essential for acute vision, and also for comfortable and safe contact lens wear. The significant efforts have been invested by the contact lens industry to develop soft lens surface that is completely wet by tear aqueous in the ocular environment. Number of the publications dedicated to the wettability properties of the soft hydrogel lenses is on the steady rise. However, the clinical results show that no unambiguous correlation emerges when lens surface wettability in vitro is judged against tear film stability evaluated in vivo. This paper assesses and compares the modern techniques used for evaluation of soft contact lens surface wettability and reports some findings regarding relations between lens surface wettability in vitro and in vivo. © 2011 EDP Sciences and Springer
5' Guanylylimidodiphosphate, a potent activator of adenylate cyclase systems in eukaryotic cells
5' Guanylylimidodiphosphate (Gpp(NH)p) stimulates adenylate cyclase [ATP pyrophosphate lyase (cyclizing), EC 4.6.1.1] activity in plasma membranes isolated from frog and salmon erythrocytes, from rat adrenal, hepatic, and fat cells, and from bovine thyroid cells. The nucleotide acts cooperatively with the various hormones (glucagon, secretin, ACTH, thyrotropin, and catecholamines) that stimulate these adenylate cyclase systems with resultant activities that equal or exceed those obtained with hormone plus GTP or with fluoride ion. In the absence of hormones, Gpp(NH)p is a considerably more effective activator than GTP, and, under certain conditions of incubation, stimulates rat fat cell adenylate cyclase to levels of activity (about 20 nmoles of 3',5' adenosine monophosphate mg protein per min) far higher than reported hitherto for any adenylate cyclase system examined. The nucleotide activates frog erythrocyte adenylate cyclase when the catecholamine receptor is blocked by the competitive antagonist, propranolol, and activates the enzyme from an adrenal tumor cell line which lacks functional ACTH receptors. In contrast, Gpp(NH)p does not stimulate adenylate cyclase in extracts from Escherichia coli B. Gpp(NH)p appears to be a useful probe for investigating the mechanism of hormone and nucleotide action on adenylate cyclase systems in eukaryotic cells.published_or_final_versio
Unit Interval Editing is Fixed-Parameter Tractable
Given a graph~ and integers , , and~, the unit interval
editing problem asks whether can be transformed into a unit interval graph
by at most vertex deletions, edge deletions, and edge
additions. We give an algorithm solving this problem in time , where , and denote respectively
the numbers of vertices and edges of . Therefore, it is fixed-parameter
tractable parameterized by the total number of allowed operations.
Our algorithm implies the fixed-parameter tractability of the unit interval
edge deletion problem, for which we also present a more efficient algorithm
running in time . Another result is an -time algorithm for the unit interval vertex deletion problem,
significantly improving the algorithm of van 't Hof and Villanger, which runs
in time .Comment: An extended abstract of this paper has appeared in the proceedings of
ICALP 2015. Update: The proof of Lemma 4.2 has been completely rewritten; an
appendix is provided for a brief overview of related graph classe
Recommended from our members
Measurement of post-lens tear thickness.
PURPOSE: A method to measure the tear film beneath a soft contact lens, referred to as post-lens tear thickness (PLTT), would have many applications to contact lens research. In this study a noninvasive technique for measuring the PLTT is presented. METHODS: The feasibility of measuring the tear layer by optical pachometry was first assessed using a model eye. The baseline corneal thickness (B) of both eyes of 21 subjects was measured, etafilcon-A ionic disposable soft contact lenses (58% water) were inserted, and the total thickness (T) of the cornea, contact lens, and PLTT were measured. After the pachometry readings the lenses were removed and their center thickness (C) determined. The PLTT was calculated using the equation: PLTT = T-(B+C). Two sets of measurements of T were performed at 15 and 25 minutes after lens insertion. The entire procedure was repeated at a second visit. RESULTS: The pachometry measurements of the small aqueous reservoir between the model eye and the lens closely matched those obtained by direct microscopic measurement. For human PLTT, the mean values (and 95% confidence intervals) for right eyes on visits 1 and 2 were 11 (8, 13) and 12 (10, 15) microm, respectively, and for left eyes were 12 (10, 15) and 11 microm (8, 14) microm, respectively. CONCLUSIONS: It is possible to measure the post-lens tear thickness using optical pachometry. The variability between repeated measurements suggests that with careful sample size planning, the technique is sufficiently precise to be useful in group assessments of PLTT
Probing the formation of intermediate- to high-mass stars in protoclusters II. Comparison between millimeter interferometric observations of NGC 2264-C and SPH simulations of a collapsing clump
The earliest phases of massive star formation in clusters are still poorly
understood. Here, we test the hypothesis for high-mass star formation proposed
in our earlier paper (Peretto et al. 2006). In order to confirm the physical
validity of this hypothesis, we carried out IRAM Plateau de Bure interferometer
observations of NGC 2264-C and performed SPH numerical simulations of the
collapse of a Jeans-unstable, prolate dense clump. Our Plateau de Bure
observations reveal the presence of a new compact source (C-MM13) located only
\~ 10000 AU away, but separated by ~ 1.1 km/s in (projected) velocity, from the
most massive Class 0 object (C-MM3) lying at the very center of NGC 2264-C.
Detailed comparison with our numerical SPH simulations supports the view that
NGC 2264-C is an elongated cluster-forming clump in the process of collapsing
and fragmenting along its long axis, leading to a strong dynamical interaction
and possible protostar merger in the central region of the clump. The present
study also sets several quantitative constraints on the initial conditions of
large-scale collapse in NGC 2264-C. Our hydrodynamic simulations indicate that
the observed velocity pattern characterizes an early phase of protocluster
collapse which survives for an only short period of time (i.e., < 10^5 yr). To
provide a good match to the observations the simulations require an initial
ratio of turbulent to gravitational energy of only ~ 5 %, which strongly
suggests that the NGC 2264-C clump is structured primarily by gravity rather
than turbulence. The required "cold'' initial conditions may result from rapid
compression by an external trigger.Comment: 15 pages, 8 figures, accepted for publication in A&
Tumor necrosis factor-α-induced protein 1 and immunity to hepatitis B virus
Aim: To compare the gene expression profile in a pair of HBV-infected twins. Methods: The gene expression profile was compared in a pair of H BV-infected twins. Results: The twins displayed different disease outco mes. One acquired natural immunity against HBV, whereas the other became a chronic HBV carrier. Eighty-eight and forty-six genes were found to be up- or downregulated in their PBMCs, respectively. Tumor necrosis factor-alpha-induced protein 1 (TNF-αIP1) that expressed at a higher level in the HBV-immune twins was identified and four pairs of siblings with HBV immunity by RT-PCR. However, upon HBV core antigen stimulation, TNF-αIP1 was downregulated in PBMCs from subjects with immunity, whereas it was slightly upregulated in HBV carriers. Bioinformatics analysis revealed a K+ channel tetramerization domain in TNF-αIP1 that shares a significant homology with some human, mouse, and C elegan proteins. Conclusion: TNF-αIP1 may play a role in the innate immunity against HBV. © 2005 The WJG Press and Elsevier Inc. All rights reserved.published_or_final_versio
Subitizing with Variational Autoencoders
Numerosity, the number of objects in a set, is a basic property of a given
visual scene. Many animals develop the perceptual ability to subitize: the
near-instantaneous identification of the numerosity in small sets of visual
items. In computer vision, it has been shown that numerosity emerges as a
statistical property in neural networks during unsupervised learning from
simple synthetic images. In this work, we focus on more complex natural images
using unsupervised hierarchical neural networks. Specifically, we show that
variational autoencoders are able to spontaneously perform subitizing after
training without supervision on a large amount images from the Salient Object
Subitizing dataset. While our method is unable to outperform supervised
convolutional networks for subitizing, we observe that the networks learn to
encode numerosity as basic visual property. Moreover, we find that the learned
representations are likely invariant to object area; an observation in
alignment with studies on biological neural networks in cognitive neuroscience
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