194 research outputs found
On the speed of convergence to stationarity of the Erlang loss system
We consider the Erlang loss system, characterized by servers, Poisson arrivals and exponential service times, and allow the arrival rate to be a function of We discuss representations and bounds for the rate of convergence to stationarity of the number of customers in the system, and display some bounds for the total variation distance between the time-dependent and stationary distributions. We also pay attention to time-dependent rates
Enhanced Antifibrinolytic Efficacy of a Plasmin-Specific Kunitz-Inhibitor (60-Residue Y11T/L17R with C-Terminal IEK) of Human Tissue Factor Pathway Inhibitor Type-2 Domain1
Current antifibrinolytic agents reduce blood loss by inhibiting plasmin active sites (e.g., aprotinin) or by preventing plasminogen/tissue plasminogen activator (tPA) binding to fibrin clots (e.g., ε-aminocaproic acid and tranexamic acid); however, they have adverse side effects. Here, we expressed 60-residue (NH2NAE . . . IEKCOOH) Kunitz domain1 (KD1) mutants of human tissue factor pathway inhibitor type-2 that inhibit plasmin as well as plasminogen activation. A single (KD1-L17R-KCOOH) and a double mutant (KD1-Y11T/L17R- KCOOH) were expressed in Escherichia coli as His-tagged constructs, each with enterokinase cleavage sites. KD1-Y11T/L17R-KCOOH was also expressed in Pichia pastoris. KD1-Y11T/L17R-KCOOH inhibited plasmin comparably to aprotinin and bound to the kringle domains of plasminogen/plasmin and tPA with Kd of ~50 nM and ~35 nM, respectively. Importantly, compared to aprotinin, KD1-L17R-KCOOH and KD1-Y11T/L17R-KCOOH did not inhibit kallikrein. Moreover, the antifibrinolytic potential of KD1-Y11T/L17R-KCOOH was better than that of KD1-L17R-KCOOH and similar to that of aprotinin in plasma clot-lysis assays. In thromboelastography experiments, KD1-Y11T/L17R-KCOOH was shown to inhibit fibrinolysis in a dose dependent manner and was comparable to aprotinin at a higher concentration. Further, KD1-Y11T/L17R-KCOOH did not induce cytotoxicity in primary human endothelial cells or fibroblasts. We conclude that KD1-Y11T/L17R-KCOOH is comparable to aprotinin, the most potent known inhibitor of plasmin and can be produced in large amounts using Pichia
Entropy Stable Numerical Schemes for Two-Fluid Plasma Equations
Two-fluid ideal plasma equations are a generalized form of the ideal MHD
equations in which electrons and ions are considered as separate species. The
design of efficient numerical schemes for the these equations is complicated on
account of their non-linear nature and the presence of stiff source terms,
especially for high charge to mass ratios and for low Larmor radii. In this
article, we design entropy stable finite difference schemes for the two-fluid
equations by combining entropy conservative fluxes and suitable numerical
diffusion operators. Furthermore, to overcome the time step restrictions
imposed by the stiff source terms, we devise time-stepping routines based on
implicit-explicit (IMEX)-Runge Kutta (RK) schemes. The special structure of the
two-fluid plasma equations is exploited by us to design IMEX schemes in which
only local (in each cell) linear equations need to be solved at each time step.
Benchmark numerical experiments are presented to illustrate the robustness and
accuracy of these schemes.Comment: Accepted in Journal of Scientific Computin
An improved method for measuring muon energy using the truncated mean of dE/dx
The measurement of muon energy is critical for many analyses in large
Cherenkov detectors, particularly those that involve separating
extraterrestrial neutrinos from the atmospheric neutrino background. Muon
energy has traditionally been determined by measuring the specific energy loss
(dE/dx) along the muon's path and relating the dE/dx to the muon energy.
Because high-energy muons (E_mu > 1 TeV) lose energy randomly, the spread in
dE/dx values is quite large, leading to a typical energy resolution of 0.29 in
log10(E_mu) for a muon observed over a 1 km path length in the IceCube
detector. In this paper, we present an improved method that uses a truncated
mean and other techniques to determine the muon energy. The muon track is
divided into separate segments with individual dE/dx values. The elimination of
segments with the highest dE/dx results in an overall dE/dx that is more
closely correlated to the muon energy. This method results in an energy
resolution of 0.22 in log10(E_mu), which gives a 26% improvement. This
technique is applicable to any large water or ice detector and potentially to
large scintillator or liquid argon detectors.Comment: 12 pages, 16 figure
All-particle cosmic ray energy spectrum measured with 26 IceTop stations
We report on a measurement of the cosmic ray energy spectrum with the IceTop
air shower array, the surface component of the IceCube Neutrino Observatory at
the South Pole. The data used in this analysis were taken between June and
October, 2007, with 26 surface stations operational at that time, corresponding
to about one third of the final array. The fiducial area used in this analysis
was 0.122 km^2. The analysis investigated the energy spectrum from 1 to 100 PeV
measured for three different zenith angle ranges between 0{\deg} and 46{\deg}.
Because of the isotropy of cosmic rays in this energy range the spectra from
all zenith angle intervals have to agree. The cosmic-ray energy spectrum was
determined under different assumptions on the primary mass composition. Good
agreement of spectra in the three zenith angle ranges was found for the
assumption of pure proton and a simple two-component model. For zenith angles
{\theta} < 30{\deg}, where the mass dependence is smallest, the knee in the
cosmic ray energy spectrum was observed between 3.5 and 4.32 PeV, depending on
composition assumption. Spectral indices above the knee range from -3.08 to
-3.11 depending on primary mass composition assumption. Moreover, an indication
of a flattening of the spectrum above 22 PeV were observed.Comment: 38 pages, 17 figure
Search for Doubly-Charged Higgs Boson Production at HERA
A search for the single production of doubly-charged Higgs bosons H^{\pm \pm}
in ep collisions is presented. The signal is searched for via the Higgs decays
into a high mass pair of same charge leptons, one of them being an electron.
The analysis uses up to 118 pb^{-1} of ep data collected by the H1 experiment
at HERA. No evidence for doubly-charged Higgs production is observed and mass
dependent upper limits are derived on the Yukawa couplings h_{el} of the Higgs
boson to an electron-lepton pair. Assuming that the doubly-charged Higgs only
decays into an electron and a muon via a coupling of electromagnetic strength
h_{e \mu} = \sqrt{4 \pi \alpha_{em}} = 0.3, a lower limit of 141 GeV on the
H^{\pm\pm} mass is obtained at the 95% confidence level. For a doubly-charged
Higgs decaying only into an electron and a tau and a coupling h_{e\tau} = 0.3,
masses below 112 GeV are ruled out.Comment: 15 pages, 3 figures, 1 tabl
Team dynamics in emergency surgery teams: results from a first international survey
Background: Emergency surgery represents a unique context. Trauma teams are often multidisciplinary and need to operate under extreme stress and time constraints, sometimes with no awareness of the trauma\u2019s causes or the patient\u2019s personal and clinical information. In this perspective, the dynamics of how trauma teams function is fundamental to ensuring the best performance and outcomes. Methods: An online survey was conducted among the World Society of Emergency Surgery members in early 2021. 402 fully filled questionnaires on the topics of knowledge translation dynamics and tools, non-technical skills, and difficulties in teamwork were collected. Data were analyzed using the software R, and reported following the Checklist for Reporting Results of Internet E-Surveys (CHERRIES). Results: Findings highlight how several surgeons are still unsure about the meaning and potential of knowledge translation and its mechanisms. Tools like training, clinical guidelines, and non-technical skills are recognized and used in clinical practice. Others, like patients\u2019 and stakeholders\u2019 engagement, are hardly implemented, despite their increasing importance in the modern healthcare scenario. Several difficulties in working as a team are described, including the lack of time, communication, training, trust, and ego. Discussion: Scientific societies should take the lead in offering training and support about the abovementioned topics. Dedicated educational initiatives, practical cases and experiences, workshops and symposia may allow mitigating the difficulties highlighted by the survey\u2019s participants, boosting the performance of emergency teams. Additional investigation of the survey results and its characteristics may lead to more further specific suggestions and potential solutions
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