248 research outputs found
The exceptional Herbig Ae star HD101412: The first detection of resolved magnetically split lines and the presence of chemical spots in a Herbig star
We obtained high-resolution, high signal-to-noise UVES and a few lower
quality HARPS spectra revealing the presence of resolved magnetically split
lines. HD101412 is the first Herbig Ae star for which the rotational Doppler
effect was found to be small in comparison to the magnetic splitting. The
measured mean magnetic field modulus varies from 2.5 to 3.5kG, while the mean
quadratic field was found to vary in the range of 3.5 to 4.8kG. To determine
the period of variations, we used radial velocity, equivalent width, line
width, and line asymmetry measurements of variable spectral lines of several
elements, as well as magnetic field measurements. The most pronounced
variability was detected for spectral lines of He I and the iron peak elements,
whereas the spectral lines of CNO elements are only slightly variable. From
spectral variations and magnetic field measurements we derived a potential
rotation period P_rot=13.86d, which has to be proven in future studies with a
larger number of observations. It is the first time that the presence of
element spots is detected on the surface of a Herbig Ae/Be star. Our previous
study of Herbig Ae stars revealed a trend towards stronger magnetic fields for
younger Herbig Ae stars, confirmed by statistical tests. This is in contrast to
a few other (non-statistical) studies claiming that magnetic Herbig Ae stars
are progenitors of the magnetic Ap stars. New developments in MHD theory show
that the measured magnetic field strengths are compatible with a current-driven
instability of toroidal fields generated by differential rotation in the
stellar interior. This explanation for magnetic intermediate-mass stars could
be an alternative to a frozen-in fossil field.Comment: 7 pages, 6 figures, 1 table, to appear in Astronomische Nachrichte
The role of cosmic ray pressure in accelerating galactic outflows
We study the formation of galactic outflows from supernova explosions (SNe)
with the moving-mesh code AREPO in a stratified column of gas with a surface
density similar to the Milky Way disk at the solar circle. We compare different
simulation models for SNe placement and energy feedback, including cosmic rays
(CR), and find that models that place SNe in dense gas and account for CR
diffusion are able to drive outflows with similar mass loading as obtained from
a random placement of SNe with no CRs. Despite this similarity, CR-driven
outflows differ in several other key properties including their overall
clumpiness and velocity. Moreover, the forces driving these outflows originate
in different sources of pressure, with the CR diffusion model relying on
non-thermal pressure gradients to create an outflow driven by internal pressure
and the random-placement model depending on kinetic pressure gradients to
propel a ballistic outflow. CRs therefore appear to be non-negligible physics
in the formation of outflows from the interstellar medium.Comment: 8 pages, 4 figures, accepted for publication in ApJL; movie of
simulated gas densities can be found here:
http://www.h-its.org/tap-images/galactic-outflows
Spirometry reference equations for central European populations from school age to old age.
Spirometry reference values are important for the interpretation of spirometry results. Reference values should be updated regularly, derived from a population as similar to the population for which they are to be used and span across all ages. Such spirometry reference equations are currently lacking for central European populations. To develop spirometry reference equations for central European populations between 8 and 90 years of age. We used data collected between January 1993 and December 2010 from a central European population. The data was modelled using "Generalized Additive Models for Location, Scale and Shape" (GAMLSS). The spirometry reference equations were derived from 118'891 individuals consisting of 60'624 (51%) females and 58'267 (49%) males. Altogether, there were 18'211 (15.3%) children under the age of 18 years. We developed spirometry reference equations for a central European population between 8 and 90 years of age that can be implemented in a wide range of clinical settings
Analysis of physical performance in children of seven to ten years old.
Capacidade f?sica ? o termo utilizado para agrupar as capacidades for?a, velocidade, resist?ncia, flexibilidade e coordena??o. O desempenho f?sico de crian?as ? preocupa??o permanente entre os especialistas da ?rea da sa?de. Esse interesse justifica-se j? que a atividade f?sica desempenha importante papel na preven??o de doen?as e melhoria da capacidade funcional. O objetivo do presente estudo foi analisar as capacidades f?sicas em crian?as de ambos os sexos. Ap?s consentimento por escrito dos pais, participaram do estudo 232 crian?as de ambos os sexos entre as idades de sete e 10 anos. A capacidade f?sica foi avaliada utilizando-se os testes de sentar e alcan?ar, resist?ncia abdominal, salto horizontal e corrida de 30 metros. Foi utilizado ANOVA two way e post hoc de Tukey para compara??o das vari?veis entre as idades e o sexo. O n?vel de signific?ncia foi de 5%. A flexibilidade n?o foi modificada pela idade e sexo. O salto horizontal e o n?mero de abdominais foram maiores nos meninos comparados ?s meninas e nas idades de 10, nove e oito anos comparados a idade de sete anos. O tempo para percorrer 30 m foi menor nos meninos comparado ?s meninas, sendo que a idade de 10 anos apresentou valores menores comparado as demais idades e as idades de nove e oito anos demonstraram menores valores comparado a idade de sete anos. De modo geral, os meninos apresentam melhor desempenho f?sico comparado ?s meninas na faixa et?ria avaliada. A idade de sete anos parece representar um per?odo de transi??o no desempenho f?sico.Physical performance is the term used to group strength, speed, endurance, flexibility and coordination capacities. The physical performance in the children is concern among experts in the field of health. This interest justified because physical activity can prevent illness and increase functional capacity. The aim of present study was assessment physical capacity in children of both sex, boys and girls. After consent of parents, concerns of study 232 children among seven and 10 years-old of both sexes. The performance motor was assessment using sit-and-reach, horizontal jump, abdominal endurance and 30 meters tests run. ANOVA Two-way and Tukey post hoc was used to compared variables among sex and ages. The significant level was 5%. Flexibility did not differ among ages and sex. The horizontal jump distance and abdominals number were higher in male group compared to the female group and eight, nine and 10 years-old were higher compared to seven years-old. The abdominals number was higher in male group compared to female group and eight, nine and 10 years-old are higher compared to seven years-old. The time to going 30 meters was small in the male group compared to female group and running time was small in the 10 years-old compared to other ages and the nine and eight years-old was small than seven years-old. In general, the boys presented better performance than girls in the ages assessment. The age seven years-old apparent represented a period of transition in the physical performance
Efeitos do cabelo da cabe?a humana no desempenho e na resposta termorregulat?ria durante a corrida de 10 km ao ar livre em homens saud?veis.
The aim of the present study was to evaluate the effects of human head hair on
performance and thermoregulatory responses during 10-km outdoor running in healthy
men. Twelve healthy males (29.5 ? 3.7 years, 174.9 ? 4.3 cm, 72.7 ? 3.2 kg and VO2max
44.6 ? 3.4 ml.kg-1.min-1) participated in two self-paced outdoor 10-km running trials
separated by 7 days: 1) HAIR, subjects ran with their natural head hair; 2) NOHAIR,
subjects ran after their hair had been totally shaved. Average running velocity was calculated
from each 2-km running time. Rectal temperature, heart rate and physiological
strain index were measured before and after the 10-km runs and at the end of each 2 km.
The rate of heat storage was measured every 2 km. The environmental stress (WBGT)
was measured every 10 min. The running velocity (10.9 ? 1 and 10.9 ? 1.1 km.h-1), heart
rate (183 ? 10 and 180 ? 12 bpm), rectal temperature (38.82 ? 0.29 and 38.81 ? 0.49oC),
physiological strain index (9 ? 1 and 9 ? 1), or heat storage rate (71.9 ? 64.1 and 80.7 ?
56.7 W.m-1) did not differ between the HAIR and NOHAIR conditions, respectively
(p>0.05). There was no difference in WBGT between the HAIR and NOHAIR conditions
(24.0 ? 1.4 and 23.2 ? 1.5?C, respectively; p=0.10). The results suggest that shaved
head hair does not alter running velocity or thermoregulatory responses during 10-km
running under the sun.O objetivo do presente estudo foi avaliar os efeitos do cabelo da cabe?a humana no
desempenho e na resposta termorregulat?ria durante 10 km de corrida ao ar livre em homens
saud?veis. Doze saud?vel do sexo masculino (29,5 ? 3,7 anos, 174,9 ? 4,3 cm, 72,7 ? 3,2 kg e
VO2m?x 44,6 ? 3,4 ml.kg-1.min-1) participaram de 2 corridas de 10km separadas por 7 dias de
intervalo em ritmo auto regulado: 1) HAIR- volunt?rios correram com seus cabelos intactos,
2) NOHAIR- volunt?rios correrram ap?s terem seus cabelos totalmente raspado. A velocidade
m?dia da corrida foi calculada a cada s?rie de 2 km. Temperatura retal, freq??ncia card?aca e
?ndice de estresse fisiol?gico foram medidos antes e depois dos 10 km da corrida e no fim de cada
2 km. Taxa de armazenamento de calor foi medida a cada 2 km. Al?m disso, o estresse ambiental
(WBGT) foi medido a cada 10 min. A velocidade de corrida (10,9 ? 1 e 10,9 ? 1,1 km.h-1),
freq??ncia card?aca (183 ? 10 e 180 ? 12 bpm), temperatura retal (38,82 ? 0,29 e 38,81 ?
0,49oC), ?ndice estresse fisiol?gico (9 ? 1 e 9 ? 1) e taxa de armazenamento de calor (71,9 ? 64,1
e 80,7 ? 56,7 Wm-1), n?o foi diferente entre as situa??es HAIR e NOHAIR, respectivamente
(p>0,05). N?o houve diferen?a no WBGT entre HAIR e NOHAIR (24,0 ? 1.4? C e 23,2 ?
1,5? C, respectivamente; p=0,10). Os resultados sugerem que raspar o cabelo da cabe?a n?o altera
a velocidade da corrida e as respostas termorregulat?rias durante 10 km de corrida sob o sol
Astrophysical turbulence modeling
The role of turbulence in various astrophysical settings is reviewed. Among
the differences to laboratory and atmospheric turbulence we highlight the
ubiquitous presence of magnetic fields that are generally produced and
maintained by dynamo action. The extreme temperature and density contrasts and
stratifications are emphasized in connection with turbulence in the
interstellar medium and in stars with outer convection zones, respectively. In
many cases turbulence plays an essential role in facilitating enhanced
transport of mass, momentum, energy, and magnetic fields in terms of the
corresponding coarse-grained mean fields. Those transport properties are
usually strongly modified by anisotropies and often completely new effects
emerge in such a description that have no correspondence in terms of the
original (non coarse-grained) fields.Comment: 88 pages, 26 figures, published in Reports on Progress in Physic
Gravitational Waves From Known Pulsars: Results From The Initial Detector Era
We present the results of searches for gravitational waves from a large selection of pulsars using data from the most recent science runs (S6, VSR2 and VSR4) of the initial generation of interferometric gravitational wave detectors LIGO (Laser Interferometric Gravitational-wave Observatory) and Virgo. We do not see evidence for gravitational wave emission from any of the targeted sources but produce upper limits on the emission amplitude. We highlight the results from seven young pulsars with large spin-down luminosities. We reach within a factor of five of the canonical spin-down limit for all seven of these, whilst for the Crab and Vela pulsars we further surpass their spin-down limits. We present new or updated limits for 172 other pulsars (including both young and millisecond pulsars). Now that the detectors are undergoing major upgrades, and, for completeness, we bring together all of the most up-to-date results from all pulsars searched for during the operations of the first-generation LIGO, Virgo and GEO600 detectors. This gives a total of 195 pulsars including the most recent results described in this paper.United States National Science FoundationScience and Technology Facilities Council of the United KingdomMax-Planck-SocietyState of Niedersachsen/GermanyAustralian Research CouncilInternational Science Linkages program of the Commonwealth of AustraliaCouncil of Scientific and Industrial Research of IndiaIstituto Nazionale di Fisica Nucleare of ItalySpanish Ministerio de Economia y CompetitividadConselleria d'Economia Hisenda i Innovacio of the Govern de les Illes BalearsNetherlands Organisation for Scientific ResearchPolish Ministry of Science and Higher EducationFOCUS Programme of Foundation for Polish ScienceRoyal SocietyScottish Funding CouncilScottish Universities Physics AllianceNational Aeronautics and Space AdministrationOTKA of HungaryLyon Institute of Origins (LIO)National Research Foundation of KoreaIndustry CanadaProvince of Ontario through the Ministry of Economic Development and InnovationNational Science and Engineering Research Council CanadaCarnegie TrustLeverhulme TrustDavid and Lucile Packard FoundationResearch CorporationAlfred P. Sloan FoundationAstronom
First narrow-band search for continuous gravitational waves from known pulsars in advanced detector data
Spinning neutron stars asymmetric with respect to their rotation axis are potential sources of
continuous gravitational waves for ground-based interferometric detectors. In the case of known pulsars a
fully coherent search, based on matched filtering, which uses the position and rotational parameters
obtained from electromagnetic observations, can be carried out. Matched filtering maximizes the signalto-
noise (SNR) ratio, but a large sensitivity loss is expected in case of even a very small mismatch
between the assumed and the true signal parameters. For this reason, narrow-band analysis methods have
been developed, allowing a fully coherent search for gravitational waves from known pulsars over a
fraction of a hertz and several spin-down values. In this paper we describe a narrow-band search of
11 pulsars using data from Advanced LIGO’s first observing run. Although we have found several initial
outliers, further studies show no significant evidence for the presence of a gravitational wave signal.
Finally, we have placed upper limits on the signal strain amplitude lower than the spin-down limit for 5 of
the 11 targets over the bands searched; in the case of J1813-1749 the spin-down limit has been beaten for
the first time. For an additional 3 targets, the median upper limit across the search bands is below the
spin-down limit. This is the most sensitive narrow-band search for continuous gravitational waves carried
out so far
Astrophysically Triggered Searches for Gravitational Waves: Status and Prospects
In gravitational-wave detection, special emphasis is put onto searches that
focus on cosmic events detected by other types of astrophysical observatories.
The astrophysical triggers, e.g. from gamma-ray and X-ray satellites, optical
telescopes and neutrino observatories, provide a trigger time for analyzing
gravitational wave data coincident with the event. In certain cases the
expected frequency range, source energetics, directional and progenitor
information is also available. Beyond allowing the recognition of gravitational
waveforms with amplitudes closer to the noise floor of the detector, these
triggered searches should also lead to rich science results even before the
onset of Advanced LIGO. In this paper we provide a broad review of LIGO's
astrophysically triggered searches and the sources they target
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