7,337 research outputs found
Study of carbonaceous nanoparticles in premixed C2H4âair flames and behind a spark ignition engine
Phosphodiesterase Type 5 Inhibitors, Sport and Doping
Phosphodiesterase type 5 inhibitors (PDE5i) (e.g., sildenafil, tadalafil, vardenafil, and avanafil) are drugs commonly used to treat erectile dysfunction, pulmonary arterial hypertension, and benign prostatic hyperplasia. PDE5i are not prohibited by the World Anti-Doping Agency (WADA) but are alleged to be frequently misused by healthy athletes to improve sporting performance. In vitro and in vivo studies have reported various effects of PDE5i on cardiovascular, muscular, metabolic, and neuroendocrine systems and the potential, therefore, to enhance performance of healthy athletes during training and competition. This suggests well-controlled research studies to examine the ergogenic effects of PDE5i on performance during activities that simulate real sporting situations are warranted to determine if PDE5i should be included on the prohibited WADA list. In the meantime, there is concern that some otherwise healthy athletes will continue to misuse PDE5i to gain an unfair competitive advantage over their competitors
DILSTORE software for ecological status assessment of lakes based on benthic diatoms
Until recently, only few diatom indices were developed for monitoring littoral zones of lakes. The
available indices are not applicable for all lake types because species lists and environmental constraintsâ ranges are
different. So far, four diatom indices (SCIL, TDIL, S, TI) were developed that use attached diatoms for ecological
status assessment therefore a need arose to ease index calculation similarly as it is a wide spread practice in status
assessment of rivers by means of the well known OMNIDIA software. DILSTORE 1.1 software has three main
functions; (i) calculation of diatom indices and community attributes; (ii) storage and listing of primary diatom
data series and (iii) it contains a taxon name coder and a spelling-check program. It can be used as a peripheral aid
to generate data sheets for the OMNIDIA. The DILSTORE 1.1 software was developed for IBM PC compatible
computers, for Windows users. According to the experiences, the DILSTORE 1.1 software can make the regular
lake monitoring practice considerably faster
Distributed Key Management for Secure Role Based Messaging
Secure Role Based Messaging (SRBM) augments messaging systems with role oriented communication in a secure manner. Role occupants can sign and decrypt messages on behalf of roles. This paper identifies the requirements of SRBM and recognises the need for: distributed key shares, fast membership revocation, mandatory security controls and detection of identity spoofing. A shared RSA scheme is constructed. RSA keys are shared and distributed to role occupants and role gate keepers. Role occupants and role gate keepers must cooperate together to use the key shares to sign and decrypt the messages. Role occupant signatures can be verified by an audit service. A SRBM system architecture is developed to show the security related performance of the proposed scheme, which also demonstrates the implementation of fast membership revocation, mandatory security control and prevention of spoofing. It is shown that the proposed scheme has successfully coupled distributed security with mandatory security controls to realize secure role based messaging
LAMP: a micro-satellite based soft X-ray polarimeter for astrophysics
The Lightweight Asymmetry and Magnetism Probe (LAMP) is a micro-satellite
mission concept dedicated for astronomical X-ray polarimetry and is currently
under early phase study. It consists of segmented paraboloidal multilayer
mirrors with a collecting area of about 1300 cm^2 to reflect and focus 250 eV
X-rays, which will be detected by position sensitive detectors at the focal
plane. The primary targets of LAMP include the thermal emission from the
surface of pulsars and synchrotron emission produced by relativistic jets in
blazars. With the expected sensitivity, it will allow us to detect polarization
or place a tight upper limit for about 10 pulsars and 20 blazars. In addition
to measuring magnetic structures in these objects, LAMP will also enable us to
discover bare quark stars if they exist, whose thermal emission is expected to
be zero polarized, while the thermal emission from neutron stars is believed to
be highly polarized due to plasma polarization and the quantum electrodynamics
(QED) effect. Here we present an overview of the mission concept, its science
objectives and simulated observational results
Illegal migration and economic growth: simulation analysis in an international context
This paper calibrates the dynamic illegal migration model studied by Hazari and Sgro (2003) to eight countries. We find that if illegal migrants and domestic labor are perfect substitutes in production, the presence of illegal migrants lowers domestic welfare between 0.09% and 2.93% among eight countries. Moreover, we show that there is a tradeoff between the long-run domestic wage rate and rental rate of capital from receiving illegal migrants.calibration
Low energy polarization sensitivity of the Gas Pixel Detector
An X-ray photoelectric polarimeter based on the Gas Pixel Detector has been
proposed to be included in many upcoming space missions to fill the gap of
about 30 years from the first (and to date only) positive measurement of
polarized X-ray emission from an astrophysical source. The estimated
sensitivity of the current prototype peaks at an energy of about 3 keV, but the
lack of readily available polarized sources in this energy range has prevented
the measurement of detector polarimetric performances.
In this paper we present the measurement of the Gas Pixel Detector
polarimetric sensitivity at energies of a few keV and the new, light, compact
and transportable polarized source that was devised and built to this aim.
Polarized photons are produced, from unpolarized radiation generated with an
X-ray tube, by means of Bragg diffraction at nearly 45 degrees.
The employment of mosaic graphite and flat aluminum crystals allow the
production of nearly completely polarized photons at 2.6, 3.7 and 5.2 keV from
the diffraction of unpolarized continuum or line emission. The measured
modulation factor of the Gas Pixel Detector at these energies is in good
agreement with the estimates derived from a Monte Carlo software, which was up
to now employed for driving the development of the instrument and for
estimating its low energy sensitivity. In this paper we present the excellent
polarimetric performance of the Gas Pixel Detector at energies where the peak
sensitivity is expected. These measurements not only support our previous
claims of high sensitivity but confirm the feasibility of astrophysical X-ray
photoelectric polarimetry.Comment: 15 pages, 12 figures. Accepted for publication in NIM
An X-ray Polarimeter for HXMT Mission
The development of micropixel gas detectors, capable to image tracks produced
in a gas by photoelectrons, makes possible to perform polarimetry of X-ray
celestial sources in the focus of grazing incidence X-ray telescopes. HXMT is a
mission by the Chinese Space Agency aimed to survey the Hard X-ray Sky with
Phoswich detectors, by exploitation of the direct demodulation technique. Since
a fraction of the HXMT time will be spent on dedicated pointing of particular
sources, it could host, with moderate additional resources a pair of X-ray
telescopes, each with a photoelectric X-ray polarimeter in the focal plane. We
present the design of the telescopes and the focal plane instrumentation and
discuss the performance of this instrument to detect the degree and angle of
linear polarization of some representative sources. Notwithstanding the limited
resources the proposed instrument can represent a breakthrough in X-ray
Polarimetry.Comment: 10 pages, 9 figure
PolarLight: a CubeSat X-ray Polarimeter based on the Gas Pixel Detector
The gas pixel detector (GPD) is designed and developed for high-sensitivity
astronomical X-ray polarimetry, which is a new window about to open in a few
years. Due to the small mass, low power, and compact geometry of the GPD, we
propose a CubeSat mission Polarimeter Light (PolarLight) to demonstrate and
test the technology directly in space. There is no optics but a collimator to
constrain the field of view to 2.3 degrees. Filled with pure dimethyl ether
(DME) at 0.8 atm and sealed by a beryllium window of 100 micron thick, with a
sensitive area of about 1.4 mm by 1.4 mm, PolarLight allows us to observe the
brightest X-ray sources on the sky, with a count rate of, e.g., ~0.2 counts/s
from the Crab nebula. The PolarLight is 1U in size and mounted in a 6U CubeSat,
which was launched into a low Earth Sun-synchronous orbit on October 29, 2018,
and is currently under test. More launches with improved designs are planned in
2019. These tests will help increase the technology readiness for future
missions such as the enhanced X-ray Timing and Polarimetry (eXTP), better
understand the orbital background, and may help constrain the physics with
observations of the brightest objects.Comment: Accepted for publication in Experimental Astronom
- âŠ