3,185 research outputs found
Accounting for Skill in Trend, Variability, and Autocorrelation Facilitates Better Multi-Model Projections: Application to the AMOC and Temperature Time Series
We present a novel quasi-Bayesian method to weight multiple dynamical models
by their skill at capturing both potentially non-linear trends and first-order
autocorrelated variability of the underlying process, and to make weighted
probabilistic projections. We validate the method using a suite of
one-at-a-time cross-validation experiments involving Atlantic meridional
overturning circulation (AMOC), its temperature-based index, as well as Korean
summer mean maximum temperature. In these experiments the method tends to
exhibit superior skill over a trend-only Bayesian model averaging weighting
method in terms of weight assignment and probabilistic forecasts. Specifically,
mean credible interval width, and mean absolute error of the projections tend
to improve. We apply the method to a problem of projecting summer mean maximum
temperature change over Korea by the end of the 21st century using a
multi-model ensemble. Compared to the trend-only method, the new method
appreciably sharpens the probability distribution function (pdf) and increases
future most likely, median, and mean warming in Korea. The method is flexible,
with a potential to improve forecasts in geosciences and other fields
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The Spitzer C2D Survey of Nearby Dense Cores: Jet and Molecular Outflow Associated With A Young Stellar Object in Core A of L1251
A long infrared jet has been discovered by the Spitzer c2d Legacy Program in core A of L1251. It is associated with a very embedded Class 0 object with an accretion luminosity of about 0.9 L(circle dot) derived by radiative transfer model fitting to the observed spectral energy distribution. Comparing the observed Infrared Array Camera colors along the infrared jet with those calculated from a model of an admixture of gas with a power-law temperature distribution indicates that the jet is possibly created by a paraboloidal bow shock propagating into the ambient medium of n(H(2)) = 10(5) cm(-3). In addition, the variation of the power-law index along the jet suggests that the portion of hot gas decreases with distance from the jet engine. The molecular outflow in this region has been mapped for the first time using CO data. From the calculated outflow momentum flux, a very strong lower limit to the average accretion luminosity is 3.6 sin i/cos(3) i L(circle dot), indicative of a decrease in the accretion rate with time.Korean government (MEST) 2009-0062865NRF R01-2007-000-20336-0NASA 1407, 1224608Astronom
Effect of warm intravenous and irrigating fluids on body temperature during transurethral resection of the prostate gland
<p>Abstract</p> <p>Background</p> <p>Transurethral resection of the prostate gland with irrigation fluid at room temperature leads to perioperative hypothermia which could give rise to adverse cardiovascular events in the perioperative period. The use of isothermic irrigation fluid reduces but does not eliminate this risk. Routine use of warm intravenous fluids along with isothermic irrigation had not been documented. This study set out to investigate the effect of the use of warm intravenous fluid together with isothermic irrigation fluid on the body temperature in patients undergoing transurethral resection of the prostate gland.</p> <p>Methods</p> <p>One hundred and twenty consented patients with obstructing benign prostatic hyperplasia were randomly assigned to one of 3 groups. Group 1 received irrigation and intravenous fluids at room temperature, group 2 received warmed irrigation fluid at 38°C along with intravenous fluid at room temperature while group 3 patients received warmed irrigation fluid and warmed intravenous fluids at 38°C. Their perioperative body temperature changes were monitored, analyzed and compared.</p> <p>Results</p> <p>The mean decrease in body temperature at the end of the procedure was significantly greater in group 1 (0.98 ± 0.56°C) than in group 2 (0.42 ± .21°C) (p < 0.001). Significantly more patients in group 1 also experienced shivering. However, in group 3, there was no significant change in the mean body temperature (p > 0.05) and none of them felt cold or shivered.</p> <p>Conclusion</p> <p>It is concluded that the use of isothermic irrigation fluid together with warm intravenous fluids during TURP prevents the occurrence of perioperative hypothermia.</p> <p>Trial registration number</p> <p>CCT-NAPN-15944</p
Ordinary-derivative formulation of conformal totally symmetric arbitrary spin bosonic fields
Conformal totally symmetric arbitrary spin bosonic fields in flat space-time
of even dimension greater than or equal to four are studied. Second-derivative
(ordinary-derivative) formulation for such fields is developed. We obtain gauge
invariant Lagrangian and the corresponding gauge transformations. Gauge
symmetries are realized by involving the Stueckelberg and auxiliary fields.
Realization of global conformal boost symmetries on conformal gauge fields is
obtained. Modified de Donder gauge condition and de Donder-Stueckelberg gauge
condition are introduced. Using the de Donder-Stueckelberg gauge frame,
equivalence of the ordinary-derivative and higher-derivative approaches is
demonstrated. On-shell degrees of freedom of the arbitrary spin conformal field
are analyzed. Ordinary-derivative light-cone gauge Lagrangian of conformal
fields is also presented. Interrelations between the ordinary-derivative gauge
invariant formulation of conformal fields and the gauge invariant formulation
of massive fields are discussed.Comment: 51 pages, v2: Results and conclusions of v1 unchanged. In Sec.3,
brief review of higher-derivative approaches added. In Sec.4, new
representations for Lagrangian, modified de Donder gauge, and de
Donder-Stueckelberg gauge added. In Sec.5, discussion of interrelations
between the ordinary-derivative and higher-derivative approaches added.
Appendices A,B,C,D and references adde
Gauge gravity duality for d-wave superconductors: prospects and challenges
We write down an action for a charged, massive spin two field in a fixed
Einstein background. Despite some technical problems, we argue that in an
effective field theory framework and in the context of the AdS/CFT
correspondence, this action can be used to study the properties of a superfluid
phase transition with a d-wave order parameter in a dual strongly interacting
field theory. We investigate the phase diagram and the charge conductivity of
the superfluid phase. We also explain how possible couplings between the spin
two field and bulk fermions affect the fermion spectral function.Comment: 42 pages, 6 figure
Development and Validation of the Behavioral Tendencies Questionnaire
At a fundamental level, taxonomy of behavior and behavioral tendencies can be described
in terms of approach, avoid, or equivocate (i.e., neither approach nor avoid). While there are
numerous theories of personality, temperament, and character, few seem to take advantage
of parsimonious taxonomy. The present study sought to implement this taxonomy by
creating a questionnaire based on a categorization of behavioral temperaments/tendencies
first identified in Buddhist accounts over fifteen hundred years ago. Items were developed
using historical and contemporary texts of the behavioral temperaments, described as
“Greedy/Faithful”, “Aversive/Discerning”, and “Deluded/Speculative”. To both maintain
this categorical typology and benefit from the advantageous properties of forced-choice
response format (e.g., reduction of response biases), binary pairwise preferences for items
were modeled using Latent Class Analysis (LCA). One sample (n1 = 394) was used to estimate
the item parameters, and the second sample (n2 = 504) was used to classify the participants
using the established parameters and cross-validate the classification against
multiple other measures. The cross-validated measure exhibited good nomothetic span
(construct-consistent relationships with related measures) that seemed to corroborate the
ideas present in the original Buddhist source documents. The final 13-block questionnaire
created from the best performing items (the Behavioral Tendencies Questionnaire or BTQ)
is a psychometrically valid questionnaire that is historically consistent, based in behavioral
tendencies, and promises practical and clinical utility particularly in settings that teach and
study meditation practices such as Mindfulness Based Stress Reduction (MBSR)
Holographic Superconductors
A holographic model of superconductors based on the action proposed by
Benini, Herzog, and Yarom [arXiv:1006.0731] is studied. This model has a
charged spin two field in an AdS black hole spacetime. Working in the probe
limit, the normalizable solution of the spin two field in the bulk gives rise
to a superconducting order parameter at the boundary of the AdS. We
calculate the fermion spectral function in this\ superconducting background and
confirm the existence of fermi arcs for non-vanishing Majorana couplings. By
changing the relative strength of the and condensations, the
position and the size of the fermi arcs are changed. When , the
spectrum becomes isotropic and the spectral function is s-wave like. By
changing the fermion mass, the fermi momentum is changed. We also calculate the
conductivity for these holographic superconductors where time reversal
symmetry has been broken spontaneously. A non-vanishing Hall conductivity is
obtained even without an external magnetic field.Comment: 24 pages,17 figures, Add more discussions on hall conductivity, two
new figures, Matched with published versio
Solitary waves in the Nonlinear Dirac Equation
In the present work, we consider the existence, stability, and dynamics of
solitary waves in the nonlinear Dirac equation. We start by introducing the
Soler model of self-interacting spinors, and discuss its localized waveforms in
one, two, and three spatial dimensions and the equations they satisfy. We
present the associated explicit solutions in one dimension and numerically
obtain their analogues in higher dimensions. The stability is subsequently
discussed from a theoretical perspective and then complemented with numerical
computations. Finally, the dynamics of the solutions is explored and compared
to its non-relativistic analogue, which is the nonlinear Schr{\"o}dinger
equation. A few special topics are also explored, including the discrete
variant of the nonlinear Dirac equation and its solitary wave properties, as
well as the PT-symmetric variant of the model
Primordial black holes under the double inflationary power spectrum
Recently, it has been shown that the primordial black holes (PBHs) produced
by near critical collapse in the expanding universe have a scaling mass
relation similar to that of black holes produced in asymptotically flat
spacetime. Distinct from PBHs formed with mass about the horizon mass (Type I),
the PBHs with the scaling relation (Type II) can be created with a range of
masses at a given formation time. In general, only the case in which the PBH
formation is concentrated at one epoch has been considered. However, it is
expected that PBH formation is possible over a broad range of epochs if the
density fluctuation has a rather large amplitude and smooth scale dependence.
In this paper, we study the PBH formation for both types assuming the power
spectrum of double inflationary models in which the small scale fluctuations
could have large amplitudes independent of the CMBR anisotropy. The mass
spectrum of Type II PBHs is newly constructed without limiting the PBH
formation period. The double inflationary power spectrum is assumed to be of
double simple power-law which are smoothly connected. Under the assumed power
spectrum, the accumulation of small PBHs formed at later times is important and
the mass range is significantly broadened for both Types. The PBH mass spectra
are far smoother than the observed MACHO spectrum due to our assumption of a
smooth spectrum. In order to fit the observation, a more spiky spectrum is
required.Comment: 7 pages including 2 figures, to be published in Phys. Rev.
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