1,833 research outputs found
An Eccentric Eclipsing Binary: CGAur
In this study, we present CG Aur's photometric observations obtained in the
observing seasons 2011 and 2012, the first available multi-colour light curves.
Their shape indicates that the system is an Algol binary. The light curve
analyses reveal that CG Aur is a detached binary system with an effective
temperature difference between the components, approximately 1000 K. The first
estimate of the absolute dimensions of the components indicated that the system
locates on the main sequence in the HR diagram. The primary component is
slightly evolved from the ZAMS.Comment: 18 pages, 6 figures, 3 table
The Effects of Long-Term Sustained Delivery of Dihydrotestosterone by Poly(lactic acid) Impregnated and Noncoated Biodegradable Ceramic Devices in Male Rodents
The objectives of this investigation were to evaluate the release of dihydrotestosterone (DHT) from nonimpregnated and poly(lactic acid) (PLA) impregnated ALCAP ceramic reservoirs implanted in male rats, and to study the effects of delivered DHT on the reproductive system of male rats. A total of 120 Sprague-Dawley male albino rats were distributed equally into three groups. Two ALCAP capsules, one nonimpregnated and the other impregnated with PLA, were implanted in each rat in groups I and II. Capsules implanted in group I rats were loaded with 40 mg DHT each. Group II rats were implanted with two empty capsules (sham group), and group III animals served as un implanted controls. Eight rats from each group were euthanized at the end of the one, three, six, nine, and twelve months following the implantation of the ceramics. No significant changes in the weights of vital organs of rats were observed among any of the three different groups. Vas deferens and epididymal fluid were devoid of normal spermatozoa within three months of implanting the steroid-containing ceramics. Testes weights decreased significantly in the rats implanted with ALCAP ceramics containing DHT and the seminiferous tubules became oligospermic after one month and azoospermic after three months. The data collected in this study suggest that: (1) ALCAP ceramic cap sules are capable of delivering DHT for one year at a sustained manner; (2) DHT delivered by ALCAP capsules can be used effectively to regulate sperma togenesis in rats.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66739/2/10.1177_088391159100600201.pd
BD+36 3317: An algol type eclipsing binary in Delta Lyrae cluster
In this paper, we present standard Johnson UBV photometry of the eclipsing
binary BD+36 3317 which is known as a member of Delta Lyrae (Stephenson 1)
cluster. We determined colors and brightness of the system, calculated E(B - V)
color excess. We discovered that the system shows total eclipse in secondary
minimum. Using this advantage, we found that the primary component of the
system has B9 - A0 spectral type. Although there is no published orbital
solution, we tried to estimate the physical properties of the system from
simultaneous analysis of UBV light curves with 2003 version of Wilson-Devinney
code. Then we considered photometric solution results together with
evolutionary models and estimated the masses of the components as M1 = 2.5 Msun
and M2 = 1.6 Msun. Those estimations gave the distance of the system as 353 pc.
Considering the uncertainties in distance estimation, resulting distance is in
agreement with the distance of Delta Lyrae cluster.Comment: 18 pages, 4 figures, 5 table
Hamiltonian LGT in the complete Fourier analysis basis
The main problem in the Hamiltonian formulation of Lattice Gauge Theories is
the determination of an appropriate basis avoiding the over-completeness
arising from Mandelstam relations. We short-cut this problem using Harmonic
analysis on Lie-Groups and intertwining operators formalism to explicitly
construct a basis of the Hilbert space. Our analysis is based only on
properties of the tensor category of Lie-Group representations. The Hamiltonian
of such theories is calculated yielding a sparse matrix whose spectrum and
eigenstates could be exactly derived as functions of the coupling Comment: LATTICE99 (theoretical developments), 3 page
Majorana solutions to the two-electron problem
A review of the known different methods and results devised to study the
two-electron atom problem, appeared in the early years of quantum mechanics, is
given, with particular reference to the calculations of the ground state energy
of helium. This is supplemented by several, unpublished results obtained around
the same years by Ettore Majorana, which results did not convey in his
published papers on the argument, and thus remained unknown until now.
Particularly interesting, even for current research in atomic and nuclear
physics, is a general variant of the variational method, developed by Majorana
in order to take directly into account, already in the trial wavefunction, the
action of the full Hamiltonian operator of a given quantum system. Moreover,
notable calculations specialized to the study of the two-electron problem show
the introduction of the remarkable concept of an effective nuclear charge
different for the two electrons (thus generalizing previous known results), and
an application of the perturbative method, where the atomic number Z was
treated effectively as a continuous variable, contributions to the ground state
energy of an atom with given Z coming also from any other Z. Instead,
contributions relevant mainly for pedagogical reasons count simple broad range
estimates of the helium ionization potential, obtained by suitable choices for
the wavefunction, as well as a simple alternative to Hylleraas' method, which
led Majorana to first order calculations comparable in accuracy with well-known
order 11 results derived, in turn, by Hylleraas.Comment: amsart, 20 pages, no figure
The basis of the physical Hilbert space of lattice gauge theories
Non-linear Fourier analysis on compact groups is used to construct an
orthonormal basis of the physical (gauge invariant) Hilbert space of
Hamiltonian lattice gauge theories. In particular, the matrix elements of the
Hamiltonian operator involved are explicitly computed. Finally, some
applications and possible developments of the formalism are discussed.Comment: 14 pages, LaTeX (Using amsmath
Heat Transfer Characteristics of Conventional Fluids and Nanofluids in Micro-Channels with Vortex Generators: A Review
An effective way to enhance the heat transfer in mini and micro electronic devices is to use different shapes of micro-channels containing vortex generators (VGs). This attracts researchers due to the reduced volume of the electronic micro-chips and increase in the heat generated from the devices. Another way to enhance the heat transfer is using nanofluids, which are considered to have great potential for heat transfer enhancement and are highly suited to application in practical heat transfer processes. Recently, several important studies have been carried out to understand and explain the causes of the enhancement or control of heat transfer using nanofluids. The main aim upon which the present work is based is to give a comprehensive review on the research progress on the heat transfer and fluid flow characteristics of nanofluids for both single- and two- phase models in different types of micro-channels. Both experimental and numerical studies have been reviewed for traditional and nanofluids in different types and shapes of micro-channels with vortex generators. It was found that the optimization of heat transfer enhancement should consider the pumping power reduction when evaluating the improvement of heat transfer
Thermal Field Theory and Generalized Light Front Coordinates
The dependence of thermal field theory on the surface of quantization and on
the velocity of the heat bath is investigated by working in general coordinates
that are arbitrary linear combinations of the Minkowski coordinates. In the
general coordinates the metric tensor is non-diagonal. The
Kubo, Martin, Schwinger condition requires periodicity in thermal correlation
functions when the temporal variable changes by an amount
. Light front quantization fails since
, however various related quantizations are possible.Comment: 10 page
Lattice QCD and the Schwarz alternating procedure
A numerical simulation algorithm for lattice QCD is described, in which the
short- and long-distance effects of the sea quarks are treated separately. The
algorithm can be regarded, to some extent, as an implementation at the quantum
level of the classical Schwarz alternating procedure for the solution of
elliptic partial differential equations. No numerical tests are reported here,
but theoretical arguments suggest that the algorithm should work well also at
small quark masses.Comment: Plain TeX source, 20 pages, figures include
Crossover between ionic/covalent and pure ionic bonding in magnesium oxyde clusters
An empirical potential with fluctuating charges is proposed for modelling
(MgO)_n clusters in both the molecular (small n) and bulk (n->infty) regimes.
Vectorial polarization forces are explicitely taken into account in the
self-consistent determination of the charges. Our model predicts cuboid cluster
structures, in agreement with previous experimental and theoretical results.
The effective charge transferred between magnesium and oxygen smoothly
increases from 1 to 2, with an estimated crossover size above 300 MgO
molecules
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