747 research outputs found
On the eclipsing cataclysmic variable star HBHA 4705-03
We present observations and analysis of a new eclipsing binary HBHA 4705-03.
Using decomposition of the light curve into accretion disk and hot spot
components, we estimated photometrically the mass ratio of the studied system
to be q=0.62 +-0.07. Other fundamental parameters was found with modeling. This
approach gave: white dwarf mass M_1 = (0.8 +- 0.2) M_sun, secondary mass
M_2=(0.497 +- 0.05) M_sun, orbital radius a=1.418 R_sun, orbital inclination i
= (81.58 +- 0.5) deg, accretion disk radius r_d/a = 0.366 +- 0.002, and
accretion rate dot{M} = (2.5 +- 2) * 10^{18}[g/s], (3*10^{-8} [M_sun/yr]).
Power spectrum analysis revealed ambiguous low-period Quasi Periodic
Oscillations centered at the frequencies f_{1}=0.00076 Hz, f_2=0.00048 Hz and
f_3=0.00036 Hz. The B-V=0.04 [mag] color corresponds to a dwarf novae during an
outburst. The examined light curves suggest that HBHA 4705-03 is a nova-like
variable star.Comment: 7 figures and 2 tables, accepted for publication in Acta Astronomic
Strategic planning for urban air mobility: Perceptions of citizens and potential users on autonomous flying vehicles
World’s current mobility systems are often inefficient and unsustainable, therefore the need for new schemes to satisfy mobility needs appears. This quest has given the impetus to the industry to invest in new technologies such as autonomous systems enabling self-driving vehicles. In this context, the concept of Urban Air Mobility (UAM), a term used for short-distance, on-demand, highly automated, passenger or cargo-carrying air mobility services, has arisen. This paper presents the introduction phase of strategic planning for the era of urban air mobility focusing on user and citizen acceptance of the system required for its operation. A survey is designed to capture the perception of citizens and potential users on aspects such as safety, security, well-being of the society (including issues of aesthetics, quality of life, social impacts), driving behaviour, mobility behaviour, expected benefits and their impact on the acceptance and the intention to use these systems. The acceptance of citizens and potential users (considered as two different groups) is analysed in terms of its potential uses (e.g. health emergencies, leisure, connectivity to remote regions). The survey is applied to the Metropolitan area of Lisbon and 207 responses were gathered. The collected data was analysed through correlation analysis and non-parametric tests. Conclusions are made on perceptions of citizens over different adoption and embracement levels.info:eu-repo/semantics/acceptedVersio
Structural Synthesis for GXW Specifications
We define the GXW fragment of linear temporal logic (LTL) as the basis for
synthesizing embedded control software for safety-critical applications. Since
GXW includes the use of a weak-until operator we are able to specify a number
of diverse programmable logic control (PLC) problems, which we have compiled
from industrial training sets. For GXW controller specifications, we develop a
novel approach for synthesizing a set of synchronously communicating
actor-based controllers. This synthesis algorithm proceeds by means of
recursing over the structure of GXW specifications, and generates a set of
dedicated and synchronously communicating sub-controllers according to the
formula structure. In a subsequent step, 2QBF constraint solving identifies and
tries to resolve potential conflicts between individual GXW specifications.
This structural approach to GXW synthesis supports traceability between
requirements and the generated control code as mandated by certification
regimes for safety-critical software. Synthesis for GXW specifications is in
PSPACE compared to 2EXPTIME-completeness of full-fledged LTL synthesis. Indeed
our experimental results suggest that GXW synthesis scales well to
industrial-sized control synthesis problems with 20 input and output ports and
beyond.Comment: The long (including appendix) version being reviewed by CAV'16
program committee. Compared to the submitted version, one author (out of her
wish) is moved to the Acknowledgement. (v2) Corrected typos. (v3) Add an
additional remark over environment assumption and easy corner case
Optimization of double pulse pumping for Ni-like Sm x-ray lasers
We report a systematic study of double pulse pumping of the Ni-like Sm x-ray laser at 73 Angstrom, currently the shortest wavelength saturated x-ray laser. It is found that the Sm x-ray laser output can change by orders of magnitude when the intensity ratio of the pumping pulses and their relative delay are varied. Optimum pumping conditions are found and interpreted in terms of a simple model. (C) 1999 American Institute of Physics. [S0021-8979(99)07102-9]
Dwarf Nova V1040 Centauri and Variable Stars in its Vicinity
We present the results of a photometric campaign of the dwarf nova V1040 Cen.
The light curve shows two normal outbursts with recurrence time ~ 40 days and
amplitude ~ 2.5 mag. Quiescence data show oscillations with periods in the
range ~ 0.1 days (2.4 h) to ~ 0.5 days (12 h) of unknown origin. We measured
the orbital period of V1040 Cen to be P_orb=0.060458(80) days (1.451+-0.002 h).
Based on the M_v-P_orb relation we found the distance of V1040 Cen to be
137+-31 pc. In this paper we also report the detection of eleven new variable
stars in the field of the monitored dwarf nova.Comment: 7 figures and 2 tables, accepted for publication in Acta Astronomic
Multidrug- and extensively drug-resistant tuberculosis
We evaluated risk factors and treatment outcomes associated with multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis (TB) in Germany in 2004–2006. In 177 (4%) of 4,557 culture-positive TB cases, Mycobacterium tuberculosis isolates were identified as MDR TB; an additional 7 (0.15%) met criteria for XDR TB. Of these 184 patients, 148 (80%) were born in countries of the former Soviet Union. In patients with XDR TB, hospitalization was longer (mean ± SD 202 ± 130 vs. 123 ± 81 days; p = 0.015) and resistance to all first-line drugs was more frequent (36% vs. 86%; p = 0.013) than in patients with MDR TB. Seventy-four (40%) of these 184 patients received treatment with linezolid. Treatment success rates ranged from 59% for the entire cohort (59% for MDR TB and 57% for XDR TB) to 87% for those with a definitive outcome (n = 125; 89% for MDR TB and 80% for XDR TB). Extensive drug susceptibility testing and availability of second- and third-line drugs under inpatient management conditions permit relatively high treatment success rates in MDR- and XDR TB
Absolute properties of the spotted eclipsing binary star CV Bootis
We present new V-band differential brightness measurements as well as new
radial-velocity measurements of the detached, circular, 0.84-day period,
double-lined eclipsing binary system CV Boo. These data along with other
observations from the literature are combined to derive improved absolute
dimensions of the stars for the purpose of testing various aspects of
theoretical modeling. Despite complications from intrinsic variability we
detect in the system, and despite the rapid rotation of the components, we are
able to determine the absolute masses and radii to better than 1.3% and 2%,
respectively. We obtain M(A) = 1.032 +/- 0.013 M(Sun) and R(B) = 1.262 +/-
0.023 R(Sun) for the hotter, larger, and more massive primary (star A), and
M(B) = 0.968 +/- 0.012 M(Sun) and R(B) = 1.173 +/- 0.023 R(Sun) for the
secondary. The estimated effective temperatures are 5760 +/- 150 K and 5670 +/-
150 K. The intrinsic variability with a period about 1% shorter than the
orbital period is interpreted as being due to modulation by spots on one or
both components. This implies that the spotted star(s) must be rotating faster
than the synchronous rate, which disagrees with predictions from current tidal
evolution models according to which both stars should be synchronized. We also
find that the radius of the secondary is larger than expected from stellar
evolution calculations by about 10%, a discrepancy also seen in other (mostly
lower-mass and active) eclipsing binaries. We estimate the age of the system to
be approximately 9 Gyr. Both components are near the end of their main-sequence
phase, and the primary may have started the shell hydrogen-burning stage.Comment: 17 pages in emulateapj format, including figures and tables. To
appear in The Astronomical Journa
Using videoconferencing to deliver anatomy teaching to medical students on clinical placements
Symbolic Implementation of Connectors in BIP
BIP is a component framework for constructing systems by superposing three
layers of modeling: Behavior, Interaction, and Priority. Behavior is
represented by labeled transition systems communicating through ports.
Interactions are sets of ports. A synchronization between components is
possible through the interactions specified by a set of connectors. When
several interactions are possible, priorities allow to restrict the
non-determinism by choosing an interaction, which is maximal according to some
given strict partial order.
The BIP component framework has been implemented in a language and a
tool-set. The execution of a BIP program is driven by a dedicated engine, which
has access to the set of connectors and priority model of the program. A key
performance issue is the computation of the set of possible interactions of the
BIP program from a given state.
Currently, the choice of the interaction to be executed involves a costly
exploration of enumerative representations for connectors. This leads to a
considerable overhead in execution times. In this paper, we propose a symbolic
implementation of the execution model of BIP, which drastically reduces this
overhead. The symbolic implementation is based on computing boolean
representation for components, connectors, and priorities with an existing BDD
package
The effects of dolomitization on petrophysical properties and fracture distribution within rift-related carbonates (Hammam Faraun Fault Block, Suez Rift, Egypt)
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