693 research outputs found
Economic Hardship and Stress among Farm Operators in North Dakota: The Suffering Effect of Social Support
The changing economic character of American agriculture is producing more than just surplus crops, it is also producing measurable increases in stress. This stress is a consequence of the faltering economic conditions in rural America (Cogner et. al,, 1986; Farmer, 1986), which has significant implications for the well-being of our rural population. Long term depression, increased suicide rates, family strain and violence are all results of this economic change (Farmer, 1986). Faraer (1986), characterized the rural sector as financially, emotionally, and socially troubled. These troubles are directly linked to the economic crisis rural America is experiencing. Social scientists and mental health professionals have expressed concern about the effects of the rural crisis on the farm population. Excessive and widespread financial difficulties have promoted increased concern which has led to psychological stress. The concept of stress is a generic term usually associated with mental tension or strain. For all its popularity, the term has only recently found its way into the medical vocabulary. One of the primary reasons for this omission has been the lack of an adequate or standardized definition of the concept (Wallis,1983). Empirical indicators of stress have ranged from migraine headaches and stomach cramps, to insomnia, lethargy, and confusion. Consequently, few studies operationalize stress the same way
A diquark model for baryons containing one heavy quark
We present a phenomenological ansatz for coupling a heavy quark with two
light quarks to form a heavy baryon. The heavy quark is treated in the heavy
mass limit, and the light quark dynamics is approximated by propagating scalar
and axial vector 'diquarks'. The resulting effective lagrangian, which
incorporates heavy quark and chiral symmetry, describes interactions of heavy
baryons with Goldstone bosons in the low energy region. As an application, the
Isgur--Wise form factors are estimated.Comment: 9 pages + 8 figures, both as uuencoded PS, discussion of Bjorken
limit (1 par + 1 fig) added, to appear in Z.Phys.
Retrograde dye perfusion of the proximal aorta - A postmortem technical study
Introduction: Multiple cardiovascular conditions can lead to unexpected fatality, which is defined as sudden
cardiac death. One of these potentially underlying conditions is aortic regurgitation, which can be caused by
discrete changes of the geometry of the proximal aorta. To analyze aortic valve competency and furthermore to
elucidate underlying pathological alterations of the coronary arteries and the vasa vasorum a perfusion method to
simulate a diastolic state was designed.
Material and methods: A postmortem approach with retrograde perfusion of the ascending aorta with methylene
blue was applied to three bodies. The procedure comprised cannulation of the brachiocephalic trunk, clamping of
the aortic arch between brachiocephalic trunk and left carotid artery, infusion of 250 ml of methylene blue, and
optical clearing of the superficial tissue layers after perfusion. Organs were examined directly following perfusion
and after optical clearing.
Results: Assessment and visualization of aortic valve competency and the vasa vasorum were possible in all three
instances. Visualization of the coronary perfusion was impaired by postmortem thrombus formation. Optical
clearing did not provide additional information.
Discussion: The method presented here is a time- and cost-efficient way of visualizing aortic valve competency and
the vasa vasorum. The visualization of the vasa vasorum highlights the potential of this method in basic research
on diseases of the great arteries and coronaries. However, for a time-efficient functional analysis of the coronaries,
other methods must be applied
Finite temperature calculations for the bulk properties of strange star using a many-body approach
We have considered a hot strange star matter, just after the collapse of a
supernova, as a composition of strange, up and down quarks to calculate the
bulk properties of this system at finite temperature with the density dependent
bag constant. To parameterize the density dependent bag constant, we use our
results for the lowest order constrained variational (LOCV) calculations of
asymmetric nuclear matter. Our calculations for the structure properties of the
strange star at different temperatures indicate that its maximum mass decreases
by increasing the temperature. We have also compared our results with those of
a fixed value of the bag constant. It can be seen that the density dependent
bag constant leads to higher values of the maximum mass and radius for the
strange star.Comment: 21 pages, 2 tables, 12 figures Astrophys. (2011) accepte
Three and four current reversals versus temperature in correlation ratchets with a simple sawtooh potential
Transport of Brownian particles on a simple sawtooth potential subjected to
both unbiased thermal and nonequilibrium symmetric three-level Markovian noise
is considered. The new effects of three and four current reversals as a
function of temperature are established in such correlation ratchets. The
parameter space coordinates of the fixed points associated with these current
reversals and the necessary and sufficient conditions for the existence of the
novel current reversals are found.Comment: 4 pages, 5 figures; some changes introduced; accepted for publication
in Physical Review
Spectrum of rotating black holes and its implications for Hawking radiation
The reduced phase space formalism for quantising black holes has recently
been extended to find the area and angular momentum spectra of four dimensional
Kerr black holes. We extend this further to rotating black holes in all
spacetime dimensions and show that although as in four dimensions the spectrum
is discrete, it is not equispaced in general. As a result, Hawking radiation
spectra from these black holes are continuous, as opposed to the discrete
spectrum predicted for four dimensional black holes.Comment: 11 pages, Revtex4. Minor changes to match version to appear in Class.
Quant. Gra
The Highly Damped Quasinormal Modes of -dimensional Reissner-Nordstrom Black Holes in the Small Charge Limit
We analyze in detail the highly damped quasinormal modes of -dimensional
Reissner-Nordstrm black holes with small charge, paying
particular attention to the large but finite damping limit in which the
Schwarzschild results should be valid. In the infinite damping limit, we
confirm using different methods the results obtained previously in the
literature for higher dimensional Reissner-Nordstrm black holes.
Using a combination of analytic and numerical techniques we also calculate the
transition of the real part of the quasinormal mode frequency from the
Reissner-Nordstrm value for very large damping to the
Schwarzschild value of for intermediate damping. The real
frequency does not interpolate smoothly between the two values. Instead there
is a critical value of the damping at which the topology of the
Stokes/anti-Stokes lines change, and the real part of the quasinormal mode
frequency dips to zero.Comment: 18 pages, 8 figure
Molecular motor that never steps backwards
We investigate the dynamics of a classical particle in a one-dimensional
two-wave potential composed of two periodic potentials, that are
time-independent and of the same amplitude and periodicity. One of the periodic
potentials is externally driven and performs a translational motion with
respect to the other. It is shown that if one of the potentials is of the
ratchet type, translation of the potential in a given direction leads to motion
of the particle in the same direction, whereas translation in the opposite
direction leaves the particle localized at its original location. Moreover,
even if the translation is random, but still has a finite velocity, an
efficient directed transport of the particle occurs.Comment: 4 pages, 5 figures, Phys. Rev. Lett. (in print
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