819 research outputs found
Effects of Service-Learning and Community Engagement Programs on the Academic Outcomes of Underrepresented Undergraduate Students
An EUV Study of the Intermediate Polar EX Hydrae
On 2000 May 5, we began a large multi-wavelength campaign to study the
intermediate polar, EX Hydrae. The simultaneous observations from six
satellites and four telescopes were centered around a one million second
observation with EUVE. Although EX Hydrae has been studied previously with
EUVE, our higher signal-to-noise observations present new results and challenge
the current IP models. Previously unseen dips in the light curve are
reminiscent of the stream dips seen in polar light curves. Also of interest is
the temporal extent of the bulge dip; approximately 0.5 in phase, implying that
the bulge extends over half of the accretion disk. We propose that the magnetic
field in EX Hydrae is strong enough (a few MG) to begin pulling material
directly from the outer edge of the disk, thereby forming a large accretion
curtain which would produce a very broad bulge dip. This would also result in
magnetically controlled accretion streams originating from the outer edge of
the disk. We also present a period analysis of the photometric data which shows
numerous beat frequencies with strong power and also intermittent and wandering
frequencies, an indication that physical conditions within EX Hya changed over
the course of the observation. Iron spectral line ratios give a temperature of
log T=6.5-6.9 K for all spin phases and a poorly constrained density of
n_e=10^10-10^11 cm^-3 for the emitting plasma. This paper is the first in a
series detailing our results from this multi-wavelength observational campaign.Comment: 27 pages, 7 figures, accepted for publication in Ap
Deciphering M-T diagram of shape memory Heusler alloys: reentrance, plateau and beyond
We present our recent results on temperature behaviour of magnetization
observed in Ni_47Mn_39In_14 Heusler alloys. Three regions can be distinguished
in the M-T diagram: (I) low temperature martensitic phase (with the Curie
temperature T_CM = 140 K), (II) intermediate mixed phase (with the critical
temperature T_MS = 230 K) exhibiting a reentrant like behavior (between T_CM
and T_MS) and (III) high temperature austenitic phase (with the Curie
temperature T_CA = 320 K) exhibiting a rather wide plateau region (between T_MS
and T_CA). By arguing that powerful structural transformations, causing drastic
modifications of the domain structure in alloys, would also trigger strong
fluctuations of the order parameters throughout the entire M-T diagram, we were
able to successfully fit all the data by incorporating Gaussian fluctuations
(both above and below the above three critical temperatures) into the
Ginzburg-Landau scenario
The X-ray Spectra of VY Scl Stars Are Not Blackbodies
Using ASCA data, we find, contrary to other researchers using ROSAT data,
that the X-ray spectra of the VY Scl stars TT Ari and KR Aur are poorly fit by
an absorbed blackbody model but are well fit by an absorbed thermal plasma
model. The different conclusions about the nature of the X-ray spectrum of KR
Aur may be due to differences in the accretion rate, since this star was in a
high optical state during the ROSAT observation, but in an intermediate optical
state during the ASCA observation. TT Ari, on the other hand, was in a high
optical state during both observations, so directly contradicts the hypothesis
that the X-ray spectra of VY Scl stars in their high optical states are
blackbodies. Instead, based on theoretical expectations and the ASCA, Chandra,
and XMM spectra of other nonmagnetic cataclysmic variables, we believe that the
X-ray spectra of VY Scl stars in their low and high optical states are due to
hot thermal plasma in the boundary layer between the accretion disk and the
surface of the white dwarf, and appeal to the acquisition of Chandra and XMM
grating spectra to test this prediction.Comment: 9 pages including 1 table and 1 encapsulated postscript figure; LaTeX
format, uses aastex.cls; accepted on 2002 January 4 for publication in The
Astrophysical Journal Letter
Лечение предопухолевых заболеваний шейки матки в сочетании с уреаплазменной инфекцией
З метою визначення клінічної і лабораторної ефективності комплексного застосування
кріодеструкції та медикаментозної терапії для лікування передпухлинних захворювань шийки матки у
сполученні з уреаплазменою інфекцією обстежено та проліковано 58 пацієнток. Розроблений і
впроваджений у клінічну практику комплексний метод лікування передпухлинних захворювань шийки
матки у сполученні з уреаплазменою інфекцією є безпечним і високоефективним (клінічна та
лабораторна ефективність становить 98,2%).To determine clinical and laboratory effectiveness of complex use of cryodestruction and drug therapy
for treatment of servical pretumour in combination with ureaplasmatic infection 58 patients have been examined
and treated.
Carried out into practice complex method of treatment of cervical pretumour in combination with
ureaplasmic.
Infection es safe and highly effective (clinical and laboratory effectiveness makes up 98,2%)
Mining the Automotive Industry: A Network Analysis of Corporate Positioning and Technological Trends
The digital transformation is driving revolutionary innovations and new
market entrants threaten established sectors of the economy such as the
automotive industry. Following the need for monitoring shifting industries, we
present a network-centred analysis of car manufacturer web pages. Solely
exploiting publicly-available information, we construct large networks from web
pages and hyperlinks. The network properties disclose the internal corporate
positioning of the three largest automotive manufacturers, Toyota, Volkswagen
and Hyundai with respect to innovative trends and their international outlook.
We tag web pages concerned with topics like e-mobility and environment or
autonomous driving, and investigate their relevance in the network. Sentiment
analysis on individual web pages uncovers a relationship between page linking
and use of positive language, particularly with respect to innovative trends.
Web pages of the same country domain form clusters of different size in the
network that reveal strong correlations with sales market orientation. Our
approach maintains the web content's hierarchical structure imposed by the web
page networks. It, thus, presents a method to reveal hierarchical structures of
unstructured text content obtained from web scraping. It is highly transparent,
reproducible and data driven, and could be used to gain complementary insights
into innovative strategies of firms and competitive landscapes, which would not
be detectable by the analysis of web content alone.Comment: Preprint version to be published in Springer Nature (presented at
CompleNet 2020
Informe juridico por el Excelentiss. Sr. Don Luis Fernandez de Cordova,...sobre que no se le diviertan, ni perturben las aguas ue nacen de los terminos de Polop, y Chirles,...con Don Antonio Montoliu, y Puigmarin,...
Subaru optical observations of the old pulsar PSR B0950+08
We report the B band optical observations of an old (17.5 Myr) radiopulsar
PSR B0950+08 obtained with the Suprime-Cam at the Subaru telescope. We detected
a faint object, B=27.07(16). Within our astrometrical accuracy it coincides
with the radio position of the pulsar and with the object detected earlier by
Pavlov et al. (1996) in UV with the HST/FOC/F130LP. The positional coincidence
and spectral properties of the object suggest that it is the optical
counterpart of PSR B0950+08. Its flux in the B band is two times higher than
one would expect from the suggested earlier Rayleigh-Jeans interpretation of
the only available HST observations in the adjacent F130LP band. Based on the B
and F130LP photometry of the suggested counterpart and on the available X-ray
data we argue in favour of nonthermal origin of the broad-band optical spectrum
of PSR B0950+08, as it is observed for the optical emission of the younger,
middle-aged pulsars PSR B0656+14 and Geminga. At the same time, the optical
efficiency of PSR B0950+08, estimated from its spin-down power and the detected
optical flux, is by several orders of magnitude higher than for these pulsars,
and comparable with that for the much younger and more energetic Crab pulsar.
We cannot exclude the presence of a compact, about 1'', faint pulsar nebula
around PSR B0950+08, elongated perpendicular to the vector of its proper
motion, unless it is not a projection of a faint extended object on the pulsar
position.Comment: 8 pages, LaTeX, aa.cls style, 5 PS figures, submitted to A&A. Image
is available in FITS format at
http://www.ioffe.rssi.ru/astro/NSG/obs/0950-subar
A population of isolated hard X-ray sources near the supernova remnant Kes 69
Recent X-ray observations of the supernova remnant IC443 interacting with
molecular clouds have shown the presence of a new population of hard X-ray
sources related to the remnant itself, which has been interpreted in terms of
fast ejecta fragment propagating inside the dense environment. Prompted by
these studies, we have obtained a deep {\sl XMM-Newton} observation of the
supernova remnant (SNR) Kes 69, which also shows signs of shock-cloud
interaction. We report on the detection of 18 hard X-ray sources in the field
of Kes 69, a significant excess of the expected galactic source population in
the field, spatially correlated with CO emission from the cloud in the remnant
environment. The spectra of 3 of the 18 sources can be described as hard power
laws with photon index <2 plus line emission associated to K-shell transitions.
We discuss the two most promising scenarios for the interpretation of the
sources, namely fast ejecta fragments (as in IC443) and cataclysmic variables.
While most of the observational evidences are consistent with the former
interpretation, we cannot rule out the latter.Comment: 9 pages, 5 figures, A&A in pres
Lectures on F-theory compactifications and model building
These lecture notes are devoted to formal and phenomenological aspects of
F-theory. We begin with a pedagogical introduction to the general concepts of
F-theory, covering classic topics such as the connection to Type IIB
orientifolds, the geometry of elliptic fibrations and the emergence of gauge
groups, matter and Yukawa couplings. As a suitable framework for the
construction of compact F-theory vacua we describe a special class of
Weierstrass models called Tate models, whose local properties are captured by
the spectral cover construction. Armed with this technology we proceed with a
survey of F-theory GUT models, aiming at an overview of basic conceptual and
phenomenological aspects, in particular in connection with GUT breaking via
hypercharge flux.Comment: Invited contribution to the proceedings of the CERN Winter School on
Supergravity, Strings and Gauge Theory 2010, to appear in Classical and
Quantum Gravity; 63 pages; v2: references added, typos correcte
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