6,804 research outputs found

    Intestinal macromolecular transport supporting adaptive immunity

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    The gastrointestinal tract performs opposing functions of nutrient absorption, barrier maintenance, and the delivery of luminal substances for the appropriate induction of tolerogenic or protective adaptive immunity. The single-layer epithelium lining the gastrointestinal tract is central to each of these functions by facilitating the uptake and processing of nutrients, providing a physical and chemical barrier to potential pathogens, and delivering macromolecular substances to the immune system to initiate adaptive immune responses. Specific transport mechanisms allow nutrient uptake and the delivery of macromolecules to the immune system while maintaining the epithelial barrier. This review examines historical observations supporting macromolecular transport by the intestinal epithelium, recent insights into the transport of luminal macromolecules to promote adaptive immunity, and how this process is regulated to promote appropriate immune responses. Understanding how luminal macromolecules are delivered to the immune system and how this is regulated may provide insight into the pathophysiology of inflammatory diseases of the gastrointestinal tract and potential preventative or therapeutic strategies. Keywords: Antigen Transport, Mucosal Tolerance, Goblet Cell

    SN1998bw: The Case for a Relativistic Shock

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    SN1998bw shot to fame by claims of association with GRB980425. Independent of its presumed association with a GRB, this SN is unusual in its radio properties. A simple interpretation of the unusually bright radio emission leads us to the conclusion that there are two shocks in this SN: a slow moving shock containing most of the ejecta and a relativistic shock (Gamma=2) which is responsible for the radio emission. This is the first evidence for the existence of relativistic shocks in supernovae. It is quite plausible that this shock may produce high energy emission (at early times and by inverse Compton scattering). As with other supernovae, we expect radio emission at much later times powered primarily by the slow moving ejecta. This expectation has motivated us to continue monitoring this unusual SN.Comment: A&A (in press), Rome GRB Symposium, Nov. 199

    Efficient Database Risk Management Using BSP and Fuzzy Logic

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    Increasing passion for internet throughout the world causes the exponential growth in the web applications and distributed techniques. Due to high usage of web applications massive transactions are happening at the database server side. Even though databases are well equipped with powerful tools, most of the times they are unable to fulfill the user’s demand and resulting in longer waiting queues or crashing of databases. So many methods and systems are existing to handle the overflowing database queries, but most of them again take longer time to get rid of the situation. This paper put forwards an idea of handling this risk situation of the database by collecting all the queries in a Queue and thereby evaluating risk aware situation by fuzzy classification. Once the risk awareness is notified then these queries in the queue are committing quickly using batch stream processing technique to avoid longer waiting queues of the queries for execution. DOI: 10.17762/ijritcc2321-8169.15079

    On associating Fast Radio Bursts with afterglows

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    A radio source that faded over six days, with a redshift of z≈0.5z\approx0.5 host, has been identified by Keane et al. (2016) as the transient afterglow to a fast radio burst (FRB 150418). We report follow-up radio and optical observations of the afterglow candidate and find a source that is consistent with an active galactic nucleus. If the afterglow candidate is nonetheless a prototypical FRB afterglow, existing slow-transient surveys limit the fraction of FRBs that produce afterglows to 0.25 for afterglows with fractional variation, m=2∣S1−S2∣/(S1+S2)≥0.7m=2|S_1-S_2|/(S_1+S_2)\geq0.7, and 0.07 for m≥1m\geq1, at 95% confidence. In anticipation of a barrage of bursts expected from future FRB surveys, we provide a simple framework for statistical association of FRBs with afterglows. Our framework properly accounts for statistical uncertainties, and ensures consistency with limits set by slow-transient surveys.Comment: Accepted version (ApJL

    Association-based image retrieval

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    With advances in the computer technology and the World Wide Web there has been an explosion in the amount and complexity of multimedia data that are generated, stored, transmitted, analyzed, and accessed. In order to extract useful information from this huge amount of data, many content-based image retrieval (CBIR) systems have been developed in the last decade. A typical CBIR system captures image features that represent image properties such as color, texture, or shape of objects in the query image and try to retrieve images from the database with similar features. Recent advances in CBIR systems include relevance feedback based interactive systems. The main advantage of CBIR systems with relevance feedback is that these systems take into account the gap between the high-level concepts and low-level features and subjectivity of human perception of visual content. In this paper, we propose a new approach for image storage and retrieval called association-based image retrieval (ABIR). We try to mimic human memory. The human brain stores and retrieves images by association. We use a generalized bi-directional associative memory (GBAM) to store associations between feature vectors. The results of our simulation are presented in the paper

    Association-based image retrieval for automatic target recognition.

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    Model-based automatic target recognition (ATR)systems deal with recognizing three dimensional objects from two dimensional images. In order to recognizeand identify objects the ATRsystem must have one or more stored models. Multiple two dimensional views of each three dimensional objectthat may appear in the universe it deals withare stored in the database. During recognition, two dimensional view of atarget object is used a query image and the search is carried out to identify the corresponding three dimensional object. Stages of a model-based ATR system include preprocessing, segmentation, feature extraction, and searching thedatabase. One of the most important problems in a model-based ATR system is to access themost likely candidate model rapidly from a large database. In this paper we propose new architecture for a model-based ATR systemthat is based on association-based image retrieval. We try to mimic human memory. The human brain retrieves images by association. We use generalized bi-directional associative memories to retrieve associated images from the database. We use the ATR system to identify military vehicles from their two dimensional views

    A Probable Optical Counterpart for the Isolated Neutron Star RX J1308.6+2127

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    Using a very deep observation with HST/STIS, we have searched for an optical counterpart to the nearby radio-quiet isolated neutron star RX J1308.6+2127 (RBS 1223). We have identified a single object in the 90% Chandra error circle that we believe to be the optical counterpart. This object has m50CCD=28.56±0.13m_{50CCD}=28.56\pm0.13 mag, which translates approximately to an unabsorbed flux of Fλ=(1.7±0.3)e−20F_{\lambda}=(1.7 \pm 0.3)e-20 ergs/s/cm^2/A at 5150 A or an X-ray-to-optical flux ratio of log(fX/fopt)=4.9log(f_X/f_opt)=4.9. This flux is a factor of ≈5\approx 5 above the extrapolation of the black-body fit to the X-ray spectrum, consistent with the optical spectra of other isolated neutron stars. Without color information we cannot conclude that this source is indeed the counterpart of RX J1308.6+2127. If not, then the counterpart must have m50CCD>29.6m_{50CCD} > 29.6 mag, corresponding to a flux that is barely consistent with the extrapolation of the black-body fit to the X-ray spectrum.Comment: 4 pages, 2 figures. Uses emulateapj5.sty, onecolfloat5.sty. Accepted by ApJ Letter

    Caustics in the sine-Gordon model from quenches in coupled 1D Bose gases

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    Caustics are singularities that occur naturally in optical, hydrodynamic and quantum waves, giving rise to high amplitude patterns that can be described using catastrophe theory. In this paper we study caustics in a statistical field theory setting in the form of the sine-Gordon model that describes a variety of physical systems including coupled 1D superfluids. Specifically, we use classical field simulations to study the dynamics of two ultracold 1D Bose gases (quasi-condensates) that are suddenly coupled to each other and find that the resulting non-equilibrium dynamics are dominated by caustics. Thermal noise is included by sampling the initial states from a Boltzmann distribution for phononic excitations. We find that caustics pile up over time in both the number and phase difference observables leading to a characteristic non-thermal `circus tent' shaped probability distribution at long times.Comment: 28 pages, 13 figure
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