11,649 research outputs found
Nuclear Bar, Star Formation and Gas Fueling in the Active Galaxy NGC 4303
A combination of Hubble Space Telescope (HST) WFPC2 and NICMOS images are
used to investigate the gas/dust and stellar structure inside the central 300
pc of the nearby active galaxy NGC 4303.
The NICMOS H-band (F160W) image reveals a bright core and a nuclear elongated
bar-like structure of 250 pc in diameter. The bar is centered on the bright
core, and its major axis is oriented in proyection along the spin axis of the
nuclear gaseous rotating disk recently detected (Colina & Arribas 1999).
The V-H (F606W - F160W) image reveals a complex gas/dust distribution with a
two-arm spiral structure of about 225 pc in radius. The southwestern arm is
traced by young star-forming knots while the northeastern arm is detected by
the presence of dust lanes. These spirals do not have a smooth structure but
rather they are made of smaller flocculent spirals or filament-like structures.
The magnitudes and colors of the star-forming knots are typical of clusters of
young stars with masses of 0.5 to 1 x yr^{-1} for about 80 Myr.Comment: ApJ, in press (February 1, 2000
Non-equilibrium hydrodynamics of a rotating filament
The nonlinear dynamics of an elastic filament that is forced to rotate at its
base is studied by hydrodynamic simulation techniques; coupling between
stretch, bend, twist elasticity and thermal fluctuations is included. The
twirling-overwhirling transition is located and found to be strongly
discontinuous. For finite bend and twist persistence length, thermal
fluctuations lower the threshold rotational frequency, for infinite persistence
length the threshold agrees with previous analytical predictions
Partly melted DNA conformations obtained with a probability peak finding method
Peaks in the probabilities of loops or bubbles, helical segments, and
unzipping ends in melting DNA are found in this article using a peak finding
method that maps the hierarchical structure of certain energy landscapes. The
peaks indicate the alternative conformations that coexist in equilibrium and
the range of their fluctuations. This yields a representation of the
conformational ensemble at a given temperature, which is illustrated in a
single diagram called a stitch profile. This article describes the methodology
and discusses stitch profiles vs. the ordinary probability profiles using the
phage lambda genome as an example.Comment: 11 pages, 9 figures; v3: major changes; v4: applications sectio
International Stock Market Efficiency: A Non-Bayesian Time-Varying Model Approach
This paper develops a non-Bayesian methodology to analyze the time-varying
structure of international linkages and market efficiency in G7 countries. We
consider a non-Bayesian time-varying vector autoregressive (TV-VAR) model, and
apply it to estimate the joint degree of market efficiency in the sense of Fama
(1970, 1991). Our empirical results provide a new perspective that the
international linkages and market efficiency change over time and that their
behaviors correspond well to historical events of the international financial
system.Comment: 21 pages, 2 tables, 6 figure
Derivation of the Quantum Probability Rule without the Frequency Operator
We present an alternative frequencists' proof of the quantum probability rule
which does not make use of the frequency operator, with expectation that this
can circumvent the recent criticism against the previous proofs which use it.
We also argue that avoiding the frequency operator is not only for technical
merits for doing so but is closely related to what quantum mechanics is all
about from the viewpoint of many-world interpretation.Comment: 12 page
Focusing of upward fluid migration beneath volcanic arcs : effect of mineral grain size variation in the mantle wedge
Author Posting. © American Geophysical Union, 2015. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry, Geophysics, Geosystems 16 (2015): 3905–3923, doi:10.1002/2015GC005950.We use numerical models to investigate the effects of mineral grain size variation on fluid migration in the mantle wedge at subduction zones and on the location of the volcanic arc. Previous coupled thermal-grain size evolution (T-GSE) models predict small grain size (<1 mm) in the corner flow of the mantle wedge, a downdip grain size increase by ∼2 orders of magnitude along the base of the mantle wedge, and finer grain size in the mantle wedge for colder-slab subduction zones. We integrate these T-GSE modeling results with a fluid migration model, in which permeability depends on grain size, and fluid flow through a moving mantle matrix is driven by fluid buoyancy and dynamic pressure gradients induced by mantle flow. Our modeling results indicate that fluids introduced along the base of the mantle wedge beneath the fore arc are initially dragged downdip by corner flow due to the small grain size and low permeability immediately above the slab. As grain size increases with depth, permeability increases, resulting in upward fluid migration. Fluids released beneath the arc and the back arc are also initially dragged downdip, but typically are not transported as far laterally before they begin to travel upward. As the fluids rise through the back-arc mantle wedge, they become deflected toward the trench due to the effect of mantle inflow. The combination of downdip migration in the fore arc and trench-ward migration in the back arc results in pathways that focus fluids beneath the arc.International Research Institute of Disaster Science, Tohoku University; NSF; MARGINS Postdoctoral Fellowship . Grant Number: NSF OCE-08408002016-05-1
Экспресс-методы диагностики психофизического состояния на занятиях по физическому воспитанию студентов высшего учебного заведения
Розглянуті прості, доступні та інформативні методи діагностування студентів в умовах учбового процесу: кольоровий тест М. Люшеру та тейпинг тест. Особливість тестування зумовле на хронічними порушеннями здоров’я студентів, які тестуються. Виокремленні та сформовані групи з різних хронічних захворювань. Тестування проводилось до заняття та після заняття. Аналіз результатів проводився з врахуванням пропозиції щодо фізичного навантаження. В ході проведеного дослідження доведено, що випробувані методи є
дієвими та доступними в умовах учбового заняття. А також, допомагають коригувати об’єм та інтенсивність фізичного навантаження; cвоєчасно та професійно проводити реабілітаційні вправи та рекреаційні заходи. Таким інформативним показником може слугувати реакція втоми відбита коричневим кольором в тестуванні М. Люшера. Також доведено, що рівень лабільності нервових процесів не однаковий в групах різних нозологій і різних учбових курсів за результатами тейпинг – тесту.The simple, accessible and informational methods of the diagnostic of the students in the conditions of study process: the color test of M. Lucher and taping test are considered. The features of the testing related chronic health problem of testing students. The group of different chronic illness are separated and formed. The testing made before and after lesson. The analysis of the results made account proposition of the physical strain. During this experiment its proved that testing methods are effective and accessible in the studying conditions. Also they help to correct the volume and intensity physical strain, in time and professionally make rehabilitees exercise and recreational action. Such informational indicator may serve the brown reaction of the tiredness in the test of M. Lusher. According the taping test its
also proved that the level of the labiality of the nervous process is different in the group of the different nozology and different studying course
The Mass Inflow Rate in the Barred Galaxy NGC 1530
Mass inflow in barred galaxies has been invoked to account for a wide variety
of phenomena, but until now direct evidence for inflow has been lacking. We
present Fabry-Perot H-alpha observations of the barred spiral galaxy NGC 1530
from which we determine velocities of the ionized gas for the entire region
swept by the bar. We compare the velocity field to models of gas flow in barred
spirals and show that it is well reproduced by ideal gas hydrodynamic models.
Inspection of the models and observations reveals that gas entering the bar
dust lanes streams directly down the dust lanes toward the 2 kpc radius nuclear
ring. The models predict that approximately 20% of the gas flowing down the
dust lane enters the nuclear ring; the remaining gas sprays around the ring to
the other bar dust lane. The fraction of the gas entering the ring is
relatively insensitive to the shape or size of the bar. Our observations of the
velocity field and dust optical depth yield a mass inflow rate into the nuclear
ring of 1 solar mass per year.Comment: 13 pages, 3 figures, aastex 4.0, accepted for publication in Ap J
Letter
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