546 research outputs found
Understanding pattern scaling errors across a range of emissions pathways
The regional climate impacts of hypothetical future emissions scenarios can be estimated by combining Earth system model simulations with a linear pattern scaling model such as MESMER (Modular Earth System Model Emulator with spatially Resolved output), which uses estimated patterns of the local response per degree of global temperature change. Here we use the mean trend component of MESMER to emulate the regional pattern of the surface temperature response based on historical single-forcer and future Shared Socioeconomic Pathway (SSP) CMIP6 (Coupled Model Intercomparison Project Phase 6) simulations. Errors in the emulations for selected target scenarios (SSP1â1.9, SSP1â2.6, SSP2â4.5, SSP3â7.0, and SSP5â8.5) are decomposed into two components, namely (1) the differences in scaling patterns between scenarios as a consequence of varying combinations of external forcings and (2) the intrinsic time series differences between the local and global responses in the target scenario. The time series error is relatively small for high-emissions scenarios, contributing around 20â% of the total error, but is similar in magnitude to the pattern error for lower-emissions scenarios. This irreducible time series error limits the efficacy of linear pattern scaling for emulating strong mitigation pathways and reduces the dependence on the predictor pattern used. The results help guide the choice of predictor scenarios for simple climate models and where to target for the introduction of other dependent variables beyond global surface temperature into pattern scaling models
Quasiparticle photoemission intensity in doped two-dimensional quantum antiferromagnets
Using the self-consistent Born approximation, and the corresponding wave
function of the magnetic polaron, we calculate the quasiparticle weight
corresponding to destruction of a real electron (in contrast to creation of a
spinless holon), as a funtion of wave vector for one hole in a generalized
model and the strong coupling limit of a generalized Hubbard model. The
results are in excellent agreement with those obtained by exact diagonalization
of a sufficiently large cluster. Only the Hubbard weigth compares very well
with photoemission measurements in Sr_2CuO_2Cl_2.Comment: 11 pages, latex, 3 figure
Gamow-Teller Strength Distribution for 37-Cl(p,n)37-Ar
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Progress Report on E356
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
The Gamow-Teller Strength Function for 37-Cl â 37-Ar
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
A Comparison of 37-Ca(p,n) Cross Sections to 37-Ca ÎČ-Decay
This research was sponsored by the National Science Foundation Grant NSF PHY-931478
Electronic localization at mesoscopic length scales: different definitions of localization and contact effects in a heuristic DNA model
In this work we investigate the electronic transport along model DNA
molecules using an effective tight-binding approach that includes the backbone
on site energies. The localization length and participation number are examined
as a function of system size, energy dependence, and the contact coupling
between the leads and the DNA molecule. On one hand, the transition from an
diffusive regime to a localized regime for short systems is identified,
suggesting the necessity of a further length scale revealing the system borders
sensibility. On the other hand, we show that the lenght localization and
participation number, do not depended of system size and contact coupling in
the thermodynamic limit. Finally we discuss possible length dependent origins
for the large discrepancies among experimental results for the electronic
transport in DNA sample
Phenomenology of flavor-mediated supersymmetry breaking
The phenomenology of a new economical SUSY model that utilizes dynamical SUSY
breaking and gauge-mediation (GM) for the generation of the sparticle spectrum
and the hierarchy of fermion masses is discussed. Similarities between the
communication of SUSY breaking through a messenger sector, and the generation
of flavor using the Froggatt-Nielsen (FN) mechanism are exploited, leading to
the identification of vector-like messenger fields with FN fields, and the
messenger U(1) as a flavor symmetry. An immediate consequence is that the first
and second generation scalars acquire flavor-dependent masses, but do not
violate FCNC bounds since their mass scale, consistent with effective SUSY, is
of order 10 TeV. We define and advocate a minimal flavor-mediated model (MFMM),
recently introduced in the literature, that successfully accommodates the small
flavor-breaking parameters of the standard model using order one couplings and
ratios of flavon field vevs. The mediation of SUSY breaking occurs via two-loop
log-enhanced GM contributions, as well as several one-loop and two-loop
Yukawa-mediated contributions for which we provide analytical expressions. The
MFMM is parameterized by a small set of masses and couplings, with values
restricted by several model constraints and experimental data. The
next-to-lightest sparticle (NLSP) always has a decay length that is larger than
the scale of a detector, and is either the lightest stau or the lightest
neutralino. Similar to ordinary GM models, the best collider search strategies
are, respectively, inclusive production of at least one highly ionizing track,
or events with many taus plus missing energy. In addition, D^0 - \bar{D}^0
mixing is also a generic low energy signal. Finally, the dynamical generation
of the neutrino masses is briefly discussed.Comment: 54 pages, LaTeX, 8 figure
Quantitative PCR tissue expression profiling of the human SGLT2 gene and related family members
SGLT2 (for âSodium GLucose coTransporterâ protein 2) is the major protein responsible for glucose reabsorption in the kidney and its inhibition has been the focus of drug discovery efforts to treat type 2 diabetes. In order to better clarify the human tissue distribution of expression of SGLT2 and related members of this cotransporter class, we performed TaqManâą (Applied Biosystems, Foster City, CA, USA) quantitative polymerase chain reaction (PCR) analysis of SGLT2 and other sodium/glucose transporter genes on RNAs from 72 normal tissues from three different individuals. We consistently observe that SGLT2 is highly kidney specific while SGLT5 is highly kidney abundant; SGLT1, sodium-dependent amino acid transporter (SAAT1), and SGLT4 are highly abundant in small intestine and skeletal muscle; SGLT6 is expressed in the central nervous system; and sodium myoinositol cotransporter is ubiquitously expressed across all human tissues
and in the Two Higgs Doublet Model with Flavor Changing Neutral Currents
A study of and is presented in the context of a Two Higgs Doublet
Model (2HDM) with flavor changing scalar currents (FCSC). Implications of the
model for the -parameter and for are also considered. The
experimental data on places stringent constraints on the model
parameters. The configuration of the model needed to account for is found
to be irreconcilable with constraints from and . In
particular, if R^{\rm exp}_b>R^{\sss{\rm SM}}_b persists then this version of
2HDM will be ruled out or require significant modifications. Noting that
aspects of the experimental analysis for and may be of some
concern, we also disregard and and give
predictions for these using constraints from and
parameter only. We emphasize the theoretical and experimental advantages of the
observable R_{b+c}\equiv \Gamma(Z\to b\bar b\mbox{ or } c\bar
c)/\Gamma(Z\to\mbox{hadrons}). We also stress the role of R_\ell\equiv
\Gamma(Z\to\mbox{hadrons})/\Gamma(Z\to \ell^+\ell^-) in testing the Standard
Model (SM) despite its dependence on QCD corrections. Noting that in models
with FCNC the amplitude for receives a contribution which grows
with , the importance and uniqueness of precision
measurements for constraining flavor changing currents is
underscored.Comment: 35 pages, 5 Postscript figures, 10 Postscript files used in the tex
file, uses epsf.st
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