226 research outputs found
Standing crops and dynamics of phytomass and minerals in two salt desert shrub communities
Of two salt desert shrub communities studied in Curlew Valley, Utah, the Atriplex confertifolia-dominated
community had 15% greater total midsummer phytomass than the Ceratoides lanata community. The
larger Atriplex shrubs contained much more woody tissue for support of photosynthetic tissues than did Ceratoides.
Atriplex aboveground phytomass and litter were about twice those of Ceratoides. Ceratoides litter was generally fine
and easily decomposable, but Atriplex litter contained about equal proportions of coarse, resistant woody tissues and
fine, easily decomposable material. Atriplex root phytomass was 1.3 times that of Ceratoides at the 2-30 cm depth,
but at depths below 30 cm, Ceratoides exhibited up to three times greater root phytomass and had 23% more root
mass overall.
Net aboveground community primary production was estimated to be about one-third greater in the A triplex than
Ceratoides community. Turnover times for readily decomposable aboveground litter were quite similar, but, because
Atriplex produced coarser litter, its overall rate was somewhat slower than that of Ceratoides.
Analyses of selected minerals in plant parts, litter, and soil revealed that about 90% of the mineral capital is in the
soil, mostly within organic matter. Nearly equivalent pools of mineral elements were found in the two communities,
except for greater Na in the Atriplex community
A tachyonic scalar field with mutually interacting components
We investigate the tachyonic cosmological potential in two
different cases of the quasi-exponential expansion of universe and discuss
various forms of interaction between the two components---matter and the
cosmological constant--- of the tachyonic scalar field, which leads to the
viable solutions of their respective energy densities. The distinction among
the interaction forms is shown to appear in the diagnostic. Further,
the role of the high- and low-redshift observations of the Hubble parameter is
discussed to determine the proportionality constants and hence the correct form
of matter--cosmological constant interaction.Comment: 14 page
Statefinder Parameter for Varying G in Three Fluid System
In this work, we have considered variable G in flat FRW universe filled with
the mixture of dark energy, dark matter and radiation. If there is no
interaction between the three fluids, the deceleration parameter and
statefinder parameters have been calculated in terms of dimensionless density
parameters which can be fixed by observational data. Also the interaction
between three fluids has been analyzed due to constant . The statefinder
parameters also calculated in two cases: pressure is constant and pressure is
variable.Comment: 5 pages, Accepted for publication in "Astrophysics and Space Science
Inpatient Transition to Virtual Care During COVID-19 Pandemic
Introduction: During the coronavirus disease 2019 (COVID-19) outbreak, novel approaches to diabetes care have been employed. Care in both the inpatient and outpatient setting has transformed considerably. Driven by the need to reduce the use of personal protective equipment and exposure for patients and providers alike, we transitioned inpatient diabetes management services to largely "virtual" or remotely provided care at our hospital. Methods: Implementation of a diabetes co-management service under the direction of the University of North Carolina division of endocrinology was initiated in July 2019. In response to the COVID-19 pandemic, the diabetes service was largely transitioned to a virtual care model in March 2020. Automatic consults for COVID-19 patients were implemented. Glycemic outcomes from before and after transition to virtual care were evaluated. Results: Data over a 15-week period suggest that using virtual care for diabetes management in the hospital is feasible and can provide similar outcomes to traditional face-to-face care. Conclusion: Automatic consults for COVID-19 patients ensure that patients with serious illness receive specialized diabetes care. Transitioning to virtual care models does not limit the glycemic outcomes of inpatient diabetes care and should be employed to reduce patient and provider exposure in the setting of COVID-19. These findings may have implications for reducing nosocomial infection in less challenging times and might address shortage of health care providers, especially in the remote areas
Spatial Periodicity of Galaxy Number Counts, CMB Anisotropy, and SNIa Hubble Diagram Based on the Universe Accompanied by a Non-Minimally Coupled Scalar Field
We have succeeded in establishing a cosmological model with a non-minimally
coupled scalar field that can account not only for the spatial
periodicity or the {\it picket-fence structure} exhibited by the galaxy -
relation of the 2dF survey but also for the spatial power spectrum of the
cosmic microwave background radiation (CMB) temperature anisotropy observed by
the WMAP satellite. The Hubble diagram of our model also compares well with the
observation of Type Ia supernovae. The scalar field of our model universe
starts from an extremely small value at around the nucleosynthesis epoch,
remains in that state for sufficiently long periods, allowing sufficient time
for the CMB temperature anisotropy to form, and then starts to grow in
magnitude at the redshift of , followed by a damping oscillation
which is required to reproduce the observed picket-fence structure of the
- relation. To realize such behavior of the scalar field, we have found
it necessary to introduce a new form of potential , with being a constant. Through this parameter ,
we can control the epoch at which the scalar field starts growing.Comment: 19 pages, 18 figures, Accepted for publication in Astrophysics &
Space Scienc
QCD ghost f(T)-gravity model
Within the framework of modified teleparallel gravity, we reconstruct a f(T)
model corresponding to the QCD ghost dark energy scenario. For a spatially flat
FRW universe containing only the pressureless matter, we obtain the time
evolution of the torsion scalar T (or the Hubble parameter). Then, we calculate
the effective torsion equation of state parameter of the QCD ghost f(T)-gravity
model as well as the deceleration parameter of the universe. Furthermore, we
fit the model parameters by using the latest observational data including
SNeIa, CMB and BAO data. We also check the viability of our model using a
cosmographic analysis approach. Moreover, we investigate the validity of the
generalized second law (GSL) of gravitational thermodynamics for our model.
Finally, we point out the growth rate of matter density perturbation. We
conclude that in QCD ghost f(T)-gravity model, the universe begins a matter
dominated phase and approaches a de Sitter regime at late times, as expected.
Also this model is consistent with current data, passes the cosmographic test,
satisfies the GSL and fits the data of the growth factor well as the LCDM
model.Comment: 19 pages, 9 figures, 2 tables. arXiv admin note: substantial text
overlap with arXiv:1111.726
Electromyographic assessment of muscle fatigue in massive rotator cuff tear
Shoulder muscle fatigue has not been assessed in massive rotator cuff tear (MRCT). This study used EMG to measure fatigability of 13 shoulder muscles in 14 healthy controls and 11 patients with MRCT. A hand grip protocol was applied to minimise artifacts due to pain experience during measurement. The fatigue index (median frequency slope) was significantly non-zero (negative) for anterior, middle, and posterior parts of deltoid, supraspinatus and subscapularis muscles in the controls, and for anterior, middle, and posterior parts of deltoid, and pectoralis major in patients (p ≤ 0.001). Fatigue was significantly greater in patients compared to the controls for anterior and middle parts of deltoid and pectoralis major (p ≤ 0.001). A submaximal grip task provided a feasible way to assess shoulder muscle fatigue in MRCT patients, however with some limitations. The results suggest increased activation of deltoid is required to compensate for lost supraspinatus abduction torque. Increased pectoralis major fatigue in patients (adduction torque) likely reflected strategy to stabilise the humeral head against superior subluxing force of the deltoid. Considering physiotherapy as a primary or adjunct intervention for the management of MRCT, the findings of this study generate a base for future clinical studies aiming at the development of evidence-based protocol
Probing Dark Energy with Supernovae: Exploiting Complementarity with the Cosmic Microwave Background
A primary goal for cosmology and particle physics over the coming decade will
be to unravel the nature of the dark energy that drives the accelerated
expansion of the Universe. In particular, determination of the
equation-of-state of dark energy, w equivalent p/rho, and its time variation,
dw/dz, will be critical for developing theoretical understanding of the new
physics behind this phenomenon. Type Ia supernovae (SNe) and cosmic microwave
background (CMB) anisotropy are each sensitive to the dark energy
equation-of-state. SNe alone can determine w(z) with some precision, while CMB
anisotropy alone cannot because of a strong degeneracy between the matter
density Omega_M and w. However, we show that the Planck CMB mission can
significantly improve the power of a deep SNe survey to probe w and especially
dw/dz. Because CMB constraints are nearly orthogonal to SNe constraints in the
Omega_M-w plane, for constraining w(z) Planck is more useful than precise
determination of Omega_M. We discuss how the CMB/SNe complementarity impacts
strategies for the redshift distribution of a supernova survey to determine
w(z) and conclude that a well-designed sample should include a substantial
number of supernovae out to redshifts z ~ 2.Comment: More discussion of CMB systematics and many new references added.
Matches the PRD versio
Cold Plus Hot Dark Matter Cosmology in the Light of Solar and Atmospheric Neutrino Oscillations
We explore the implications of possible neutrino oscillations, as indicated
by the solar and atmospheric neutrino experiments, for the cold plus hot dark
matter scenario of large scale structure formation. We find that there are
essentially three distinct schemes that can accommodate the oscillation data
and which also allow for dark matter neutrinos. These include (i) three nearly
degenerate (in mass) neutrinos, (ii) non-degenerate masses with in
the eV range, and (iii) nearly degenerate pair (in the eV
range), with the additional possibility that the electron neutrino is
cosmologically significant. The last two schemes invoke a `sterile' neutrino
which is light (< or ~ eV). We discuss the implications of these schemes for
and oscillation, and find
that scheme (ii) in particular, predicts them to be in the observable range. As
far as structure formation is concerned, we compare the one neutrino flavor
case with a variety of other possibilities, including two and three degenerate
neutrino flavors. We show, both analytically and numerically, the effects of
these neutrino mass scenarios on the amplitude of cosmological density
fluctuations. With a Hubble constant of 50 km s Mpc, a spectral
index of unity, and , the two and three flavor
scenarios fit the observational data marginally better than the single flavor
scheme. However, taking account of the uncertainties in these parameters, we
show that it is premature to pick a clear winner.Comment: 1 LaTEX file plus 1 uuencoded Z-compressed tar file with 3 postscript
figure
Effects of sleep deprivation on neural functioning: an integrative review
Sleep deprivation has a broad variety of effects on human performance and neural functioning that manifest themselves at different levels of description. On a macroscopic level, sleep deprivation mainly affects executive functions, especially in novel tasks. Macroscopic and mesoscopic effects of sleep deprivation on brain activity include reduced cortical responsiveness to incoming stimuli, reflecting reduced attention. On a microscopic level, sleep deprivation is associated with increased levels of adenosine, a neuromodulator that has a general inhibitory effect on neural activity. The inhibition of cholinergic nuclei appears particularly relevant, as the associated decrease in cortical acetylcholine seems to cause effects of sleep deprivation on macroscopic brain activity. In general, however, the relationships between the neural effects of sleep deprivation across observation scales are poorly understood and uncovering these relationships should be a primary target in future research
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