4,401 research outputs found

    Activation of prothrombin accompanying thrombolysis with recombinant tissue-type plasminogen activator

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    AbstractIncreases in thrombin activity in patients given fibrinolytic agents for acute myocardial infarction have been shown to be important in limiting the ultimate success of coronary thrombolysis. The present study was designed to determine whether increases in thrombin activity reflect, in part, activation of prothrombin accompanying thrombolysis. Plasma concentrations of prothrombin fragment 1.2, a polypeptide released when prothrombin is activated by factor Xa, were measured in 22 patients with acute myocardial infarction before and after treatment with 100 mg of recombinant tissue-type plasminogen activator (rt-PA). Concentrations of prothrombin fragment 1.2 increased from 0.83 ± 1.1 nM(mean ± SD) before rt-PA infusion to 1.5 ± 1.5 nM2 h after initiation of the infusion (p < 0.05). After a 5,000-U intravenous dose of heparin given at the end of the infusion of rt-PA, concentrations of prothrombin fragment 1.2 decreased from 1.8 ± 1.5 to 1.1 ± 0.9 nM(n = 20, p < 0.05), although values were still increased compared with concentrations before rt-PA.These results indicate that thrombin activity increases in patients given rt-PA at least in part because of activation of the coagulation system leading to activation of prothrombin. Thus, inhibition of the reactions involving coagulant proteins that lead to activation of prothrombin may be of value as conjunctive treatment to potentiate the efficacy of pharmacologic thrombolysis

    Statistical Mechanics of the Hyper Vertex Cover Problem

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    We introduce and study a new optimization problem called Hyper Vertex Cover. This problem is a generalization of the standard vertex cover to hypergraphs: one seeks a configuration of particles with minimal density such that every hyperedge of the hypergraph contains at least one particle. It can also be used in important practical tasks, such as the Group Testing procedures where one wants to detect defective items in a large group by pool testing. Using a Statistical Mechanics approach based on the cavity method, we study the phase diagram of the HVC problem, in the case of random regualr hypergraphs. Depending on the values of the variables and tests degrees different situations can occur: The HVC problem can be either in a replica symmetric phase, or in a one-step replica symmetry breaking one. In these two cases, we give explicit results on the minimal density of particles, and the structure of the phase space. These problems are thus in some sense simpler than the original vertex cover problem, where the need for a full replica symmetry breaking has prevented the derivation of exact results so far. Finally, we show that decimation procedures based on the belief propagation and the survey propagation algorithms provide very efficient strategies to solve large individual instances of the hyper vertex cover problem.Comment: Submitted to PR

    Rapid Miocene Exhumation to the East of the Tauern Window

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    The Eastern Alps were substantially shaped by northward movement of the Dolomites Indenter and eastward extrusion of the orogenic wedge in front of the indenter. A resulting sinistral wrench zone runs through the western Tauern Window (TW) and continues along the Salzach-Ennstal-Mariazell-Puchberg Fault (SEMP) eastward. Low-T thermochronological studies demonstrate rapid Miocene cooling of the TW units from ≄ 350 °C to below ~ 80 °C due to folding and coeval erosion. Thermochronologic ages in the Eastern Tauern Window range between 12 Ma to 22 Ma for the zircon fission track chronometer (partial annealing zone (PAZ) ~ 200 – 350°C, e.g., Tagami et al., 1996) and 5 Ma to 13 Ma for the apatite (U-Th)/He chronometer (partial retention zone (PRZ) ~ 40 – 80°C, Stockli et al., 2000). Ages for the zircon (U-Th)/He and apatite fission track chronometers fall in between. Along the eastern margin of the TW, the extensional Katschberg Fault-System (KFS) decoupled the Gurktal Block (GB) in its hanging wall from folding. The KFS was active between 20 and 17 Ma, in the early Miocene (Scharf et al., 2016). A late reactivation phase is demonstrated by reset or partially reset zircon and apatite fission track ages within the footwall towards the fault, yielding Late Miocene to Pliocene ages (Bertrand et al., 2017). A similar younging trend is observed within the TW towards the Brenner Fault in the western TW. The GB in the hanging wall of the KFS preserves a rapid Cretaceous and Eocene cooling through the zircon fission track PAZ and rapid Oligocene to Miocene cooling through the apatite fission track PAZ (Wölfler et al., 2023). The Niedere Tauern (NT), north of the GB and south of the SEMP line, seem to be structurally closely linked to the TW. They show a similar rapid Miocene cooling history and an intervening Cenozoic structure between the TW and the NT is missing. Published apatite fission track ages range between 14 Ma and 24 Ma (apatite PAZ ~ 60 – 100°C, Wagner et al., 1989). Published apatite (U-Th)/He ages from the southern boundary of the NT range between 6 Ma and 7 Ma, indicating a Late Miocene cooling below ~ 80 °C (Wölfler et al., 2016). Our (U-Th)/He analysis from the interiour of the NT revealed ages of around 20 Ma to 23 Ma (zircon (U-Th)/He), and 11 Ma to 22 Ma (apatite (U-Th)/He). Published apatite fission track ages fall in between and partly overlap with our results. This demonstrates a rapid cooling pulse in the Miocene, exhuming at least the western part of the NT from ≄ 200 °C to below ~ 80 °C. Published AHe ages of ~ 6 Ma along the southern margin of the NT might relate to late Miocene normal faulting along the complex Murtal Fault-System (MFS). A pronounced jump towards older thermochronologic ages in the Seckauer Tauern, east of the Pöls fault and extensional structures along this fault indicate a structural decoupling of the western NT from the Seckauer Tauern. In this contribution, we discuss the linkage between TW and N T and characterize in greater detail the exhumation history along the eastern wrench zone

    Neutrino-induced deuteron disintegration experiment

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    Cross sections for the disintegration of the deuteron via neutral-current (NCD) and charged-current (CCD) interactions with reactor antineutrinos are measured to be 6.08 +/- 0.77 x 10^(-45) cm-sq and 9.83 +/- 2.04 x 10^(-45) cm-sq per neutrino, respectively, in excellent agreement with current calculations. Since the experimental NCD value depends upon the CCD value, if we use the theoretical value for the CCD reaction, we obtain the improved value of 5.98 +/- 0.54 x 10^(-45) for the NCD cross section. The neutral-current reaction allows a unique measurement of the isovector-axial vector coupling constant in the hadronic weak interaction (beta). In the standard model, this constant is predicted to be exactly 1, independent of the Weinberg angle. We measure a value of beta^2 = 1.01 +/- 0.16. Using the above improved value for the NCD cross section, beta^2 becomes 0.99 +/- 0.10.Comment: 22pages, 9 figure

    Occupational choice, number of entrepreneurs and output: theory and empirical evidence with Spanish data

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    This paper extends the (Lucas, Bell J Econ 9:508–523,1978) model of occupational choices by individuals with different skills, beyond the simple options of self-employment or wage-employment, by including a second choice for the self-employed. That is, an option to hire employees and so become self-employed with employees (SEWEs), or to be self-employed without employees (SEWNEs). We solve for the market equilibrium and examine the sensitivity of relative sizes of occupational groups, and of the level of productivity, to changes in the exogenous parameters. The results show that the positive (negative) association between number of SEWEs (SEWNEs) and productivity, observed in the Spanish data, can be explained, under certain conditions, as the result of cross-region and time differences in average skills. These findings point to the importance of distinguishing between SEWEs and SEWNEs in drawing valid conclusions concerning any link between entrepreneurship and economic development

    Expression of Interest: The Atmospheric Neutrino Neutron Interaction Experiment (ANNIE)

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    Submitted for the January 2014 Fermilab Physics Advisory Committee meetingSubmitted for the January 2014 Fermilab Physics Advisory Committee meetingSubmitted for the January 2014 Fermilab Physics Advisory Committee meetingSubmitted for the January 2014 Fermilab Physics Advisory Committee meetingNeutron tagging in Gadolinium-doped water may play a significant role in reducing backgrounds from atmospheric neutrinos in next generation proton-decay searches using megaton-scale Water Cherenkov detectors. Similar techniques might also be useful in the detection of supernova neutrinos. Accurate determination of neutron tagging efficiencies will require a detailed understanding of the number of neutrons produced by neutrino interactions in water as a function of momentum transferred. We propose the Atmospheric Neutrino Neutron Interaction Experiment (ANNIE), designed to measure the neutron yield of atmospheric neutrino interactions in gadolinium-doped water. An innovative aspect of the ANNIE design is the use of precision timing to localize interaction vertices in the small fiducial volume of the detector. We propose to achieve this by using early production of LAPPDs (Large Area Picosecond Photodetectors). This experiment will be a first application of these devices demonstrating their feasibility for Water Cherenkov neutrino detectors

    Majorana Neutrinos and Gravitational Oscillation

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    We analyze the possibility of encountering resonant transitions of high energy Majorana neutrinos produced in Active Galactic Nuclei (AGN). We consider gravitational, electromagnetic and matter effects and show that the latter are ignorable. Resonant oscillations due to the gravitational interactions are shown to occur at energies in the PeV range for magnetic moments in the 10−17ÎŒB10^{-17} \mu_B range. Coherent precession will dominate for larger magnetic moments. The alllowed regions for gravitational resonant transitions are obtained.Comment: 11 pages, 8 figures, Latex; requires revtex and epsf.tex submitted to Physical Review

    Expression of Interest: The Atmospheric Neutrino Neutron Interaction Experiment (ANNIE)

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    Neutron tagging in Gadolinium-doped water may play a significant role in reducing backgrounds from atmospheric neutrinos in next generation proton-decay searches using megaton-scale Water Cherenkov detectors. Similar techniques might also be useful in the detection of supernova neutrinos. Accurate determination of neutron tagging efficiencies will require a detailed understanding of the number of neutrons produced by neutrino interactions in water as a function of momentum transferred. We propose the Atmospheric Neutrino Neutron Interaction Experiment (ANNIE), designed to measure the neutron yield of atmospheric neutrino interactions in gadolinium-doped water. An innovative aspect of the ANNIE design is the use of precision timing to localize interaction vertices in the small fiducial volume of the detector. We propose to achieve this by using early production of LAPPDs (Large Area Picosecond Photodetectors). This experiment will be a first application of these devices demonstrating their feasibility for Water Cherenkov neutrino detectors.Comment: Submitted for the January 2014 Fermilab Physics Advisory Committee meetin
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