428 research outputs found
Clopidogrel: A Pharmacogenomic Perspective on its Use in Coronary Artery Disease
The thienopyridine antiplatelet agent clopidogrel is an effective drug for the prevention of vascular events. However, data has accumulated over time to suggest it is prone to significant interpatient variability. While there are several factors that contribute to this, one of the most important is variability in forming the active metabolite necessary for clopidogrel function. Several enzymes are involved in formation of this metabolite, and two, CYP2C19 and P-glycoprotein, appear to have alleles that both occur frequently in the population and have a clinically significant impact. Patients carrying these alleles can be identified, but it remains to be determined if this information is necessary or sufficient for risk stratification. Furthermore, if patients with high-risk alleles are identified, it is unclear how treatment should be adjusted
The Neural Control of a Robot in the Conditions of Movable Obstacles
The proposed concept of robot control assisting uses a neural network, whose operation relies on the activation of neurons delimiting a path from the source to the target with evading movable obstacles The complexity of the control algorithm is O (n). The proposed adjustment of neuron sensitivity using a two-element pencils of planes passing over the shortest path of the robot makes it possible to obtain a set of solutions with simultaneous classification in terms of a very important path length criterion.Предложена концепция сопровождения управления роботом с использованием нейронной сети, работа которой основана на активизации нейронов, определяющих путь от исходной точки до цели с уклонением от подвижных препятствий. Сложность алгоритма управления составляет О (n). Предложенная настройка нейронной чувствительности с использованием двухэлементных пучков плоскостей, пересекающих кратчайший путь робота, позволяет получить множество решений с одновременной классификацией по критерию длины пути.Запропоновано концепцію супроводу управління роботом з використанням нейронної мережі, робота якої базується на активізації нейронів, що визначають шлях від вихідної точки до цілі з відхиленням від рухомих перешкод. Складність алгоритму управління складає On(). Запропоноване настроювання нейронної чутливості з використанням двоелементних пучків площин, що перетинають найкоротший шлях робота, дозволяє отримати велику кількість рішень з одночасною класифікацією за критерієм довжини шляху
The SUrvey for Pulsars and Extragalactic Radio Bursts V:Recent Discoveries and Full Timing Solutions
The SUrvey for Pulsars and Extragalactic Radio Bursts ran from 2014 April to
2019 August, covering a large fraction of the southern hemisphere at mid- to
high-galactic latitudes, and consisting of 9-minute pointings taken with the
20-cm multibeam receiver on the Parkes Radio Telescope. Data up to 2017
September 21 have been searched using standard Fourier techniques, single-pulse
searches, and Fast Folding Algorithm searches. We present 19 new discoveries,
bringing the total to 27 discoveries in the programme, and we report the
results of follow-up timing observations at Parkes for 26 of these pulsars,
including the millisecond pulsar PSR J1421-4409; the faint, highly-modulated,
slow pulsar PSR J1646-1910; and the nulling pulsar PSR J1337-4441. We present
new timing solutions for 23 pulsars, and we report flux densities, modulation
indices, and polarization properties.Comment: Accepted to MNRAS; data available at
https://doi.org/10.5281/zenodo.390098
Giant pulses from J1823-3021A observed with the MeerKAT telescope
The millisecond pulsar J1823-3021A is a very active giant pulse emitter in
the globular cluster NGC 6624. New observations with the MeerKAT radio
telescope have revealed 14350 giant pulses over 5 hours of integration time,
with an average wait time of about 1 second between giant pulses. The giant
pulses occur in phases compatible with the ordinary radio emission, follow a
power-law distribution with an index of -2.63 0.02 and contribute 4
percent of the total integrated flux. The spectral index of the giant pulses
follows a Gaussian distribution centered around -1.9 with a standard deviation
of 0.6 and is on average flatter than the integrated emission, which has a
spectral index of -2.81 0.02. The waiting times between the GPs are
accurately described by a Poissonian distribution, suggesting that the time of
occurrence of a GP is independent from the times of occurrence of other GPs. 76
GPs show multiple peaks within the same rotation, a rate that is also
compatible with the mutual independence of the GP times of occurrence. We
studied the polarization properties of the giant pulses finding, on average,
linear polarization only at the 1 percent level and circular polarization at
the 3 percent level, similar to the polarization percentages of the total
integrated emission. In 4 cases it was possible to measure the RM of the GPs
which are highly variable and, in two cases, is inconsistent with the mean RM
of the total integrated pulsar signal.Comment: Accepted for publication in MNRAS. 8 Pages, 11 Figure
The Thousand Pulsar Array program on MeerKAT – IX. The time-averaged properties of the observed pulsar population
We present the largest single survey to date of average profiles of radio pulsars, observed and processed using the same telescope and data reduction software. Specifically, we present measurements for 1170 pulsars, observed by the Thousand Pulsar Array programme at the 64-dish SARAO MeerKAT radio telescope, in a frequency band from 856 to 1712 MHz. We provide rotation measures (RM), dispersion measures, flux densities, and polarization properties. The catalogue includes 254 new RMs that substantially increase the total number of known pulsar RMs. Our integration times typically span over 1000 individual rotations per source. We show that the radio (pseudo-) luminosity has a strong, shallow dependence on the spin-down energy, proportional to Ė0.15±0.04, that contradicts some previous proposals of population synthesis studies. In addition, we find a significant correlation between the steepness of the observed flux density spectra and Ė, and correlations of the fractional linear polarization with Ė, the spectral index, and the pulse width, which we discuss in the context of what is known about pulsar radio emission and how pulsars evolve with time. On the whole, we do not see significant correlations with the estimated surface magnetic field strength, and the correlations with Ė are much stronger than those with the characteristic age. This finding lends support to the suggestion that magnetic dipole braking may not be the dominant factor for the evolution of pulsar rotation over the lifetimes of pulsars. A public data release of the high-fidelity time-averaged pulse profiles in full polarization accompanies our catalogue
The Green Bank North Celestial Cap Pulsar Survey. IV: Four New Timing Solutions
We present timing solutions for four pulsars discovered in the Green Bank
Northern Celestial Cap (GBNCC) survey. All four pulsars are isolated with spin
periods between 0.26s and 1.84s. PSR J00382501 has a 0.26s
period and a period derivative of ,
which is unusually low for isolated pulsars with similar periods. This low
period derivative may be simply an extreme value for an isolated pulsar or it
could indicate an unusual evolution path for PSR J00382501, such as a
disrupted recycled pulsar (DRP) from a binary system or an orphaned central
compact object (CCO). Correcting the observed spin-down rate for the Shklovskii
effect suggests that this pulsar may have an unusually low space velocity,
which is consistent with expectations for DRPs. There is no X-ray emission
detected from PSR J00382501 in an archival swift observation, which suggests
that it is not a young orphaned CCO. The high dispersion measure of PSR
J1949+3426 suggests a distance of 12.3kpc. This distance indicates that PSR
J1949+3426 is among the most distant 7% of Galactic field pulsars, and is one
of the most luminous pulsars.Comment: 7 pages, 5 figure
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