336 research outputs found
Dark matter and sub-GeV hidden U(1) in GMSB models
Motivated by the recent PAMELA and ATIC data, one is led to a scenario with
heavy vector-like dark matter in association with a hidden sector
below GeV scale. Realizing this idea in the context of gauge mediated
supersymmetry breaking (GMSB), a heavy scalar component charged under
is found to be a good dark matter candidate which can be searched for direct
scattering mediated by the Higgs boson and/or by the hidden gauge boson. The
latter turns out to put a stringent bound on the kinetic mixing parameter
between and : . For the typical range
of model parameters, we find that the decay rates of the ordinary lightest
neutralino into hidden gauge boson/gaugino and photon/gravitino are comparable,
and the former decay mode leaves displaced vertices of lepton pairs and missing
energy with distinctive length scale larger than 20 cm for invariant lepton
pair mass below 0.5 GeV. An unsatisfactory aspect of our model is that the
Sommerfeld effect cannot raise the galactic dark matter annihilation by more
than 60 times for the dark matter mass below TeV.Comment: 1+15 pages, 4 figures, version published in JCAP, references added,
minor change
On the massless "just-so" solution to the solar neutrino problem
We study the effect of the non-resonant, vacuum oscillation-like neutrino
flavor conversion induced by non-standard flavor changing and non-universal
flavor diagonal neutrino interactions with electrons in the sun. We have found
an acceptable fit for the combined analysis for the solar experiments total
rates, the Super-Kamiokande (SK) energy spectrum and zenith angle dependence.
Phenomenological constraints on non-standard flavor changing and non-universal
flavor diagonal neutrino interactions are considered.Comment: 4 pages, Latex, uses eps
Does Culture Impact Preferred Employee attributes in Complaint Handling Encounters?
Recently, Gruber et al.’s (2011) Kano study revealed that complaining customers in Saudi Arabia are less difficult to delight than UK customers. The present study investigates whether these differences are caused by different service sector development stages, as suggested in their study, or by cultural differences instead. Data were collected using Kano questionnaires from 151 respondents with complaining experience in Singapore. This country was chosen as it has a highly developed service economy (like the UK) but also a collectivistic culture (like Saudi Arabia). The analysis reveals that Singaporean customers show the same preferences as those in the UK. We consider this as a strong indicator for the suggested impact of the stage of service sector development rather than cultural differences on complaining customers’ preferences of frontline employee attributes. Our results support the findings by Gruber et al. (2011). By doing so, they surprisingly refute previous research which concluded that national culture plays a significant role in shaping customer expectations during complaint handling encounters. Our study especially corroborates the notion of a life cycle of quality attributes that had been found for goods and services and the preferred attributes of frontline employees dealing with customer complaints
Cross Section Measurements of Charged Pion Photoproduction in Hydrogen and Deuterium from 1.1 to 5.5 GeV
The differential cross section for the gamma +n --> pi- + p and the gamma + p
--> pi+ n processes were measured at Jefferson Lab. The photon energies ranged
from 1.1 to 5.5 GeV, corresponding to center-of-mass energies from 1.7 to 3.4
GeV. The pion center-of-mass angles varied from 50 degree to 110 degree. The
pi- and pi+ photoproduction data both exhibit a global scaling behavior at high
energies and high transverse momenta, consistent with the constituent counting
rule prediction and the existing pi+ data. The data suggest possible
substructure of the scaling behavior, which might be oscillations around the
scaling value. The data show an enhancement in the scaled cross section at
center-of-mass energy near 2.2 GeV. The differential cross section ratios at
high energies and high transverse momenta can be described by calculations
based on one-hard-gluon-exchange diagrams.Comment: 18 pages, 19 figure
Enhancing clinical decision support with genomic tools in breast cancer: a Scottish perspective
Introduction:
The Oncotype DX Breast RS test has been adopted in Scotland and has been the subject of a large population-based study by a Scottish Consensus Group to assess the uptake of the recurrence score (RS), evaluate co-variates associated with the RS and to analyse the effect it may have had on clinical practice.
Materials & Methods: Pan-Scotland study between August 2018–August 2021 evaluating 833 patients who had a RS test performed as part of their diagnostic pathway. Data was extracted retrospectively from electronic records and analysis conducted to describe change in chemotherapy administration (by direct comparison with conventional risk assessment tools), and univariate/multivariate analysis to assess relationship between covariates and the RS.
Results:
Chemotherapy treatment was strongly influenced by the RS (p < 0.001). Only 30 % of patients received chemotherapy treatment in the intermediate and high risk PREDICT groups, where chemotherapy is considered. Additionally, 55.5 % of patients with a high risk PREDICT had a low RS and did not receive chemotherapy. There were 17 % of patients with a low risk PREDICT but high RS who received chemotherapy.
Multivariate regression analysis showed the progesterone receptor Allred score (PR score) to be a strong independent predictor of the RS, with a negative PR score being associated with high RS (OR 4.49, p < 0.001). Increasing grade was also associated with high RS (OR 3.81, p < 0.001). Classic lobular pathology was associated with a low RS in comparison to other tumour pathology (p < 0.01). Nodal disease was associated with a lower RS (p = 0.012) on univariate analysis, with menopausal status (p = 0.43) not influencing the RS on univariate or multivariate analysis.
Conclusions:
Genomic assays offer the potential for risk-stratified decision making regarding the use of chemotherapy. They can help reduce unnecessary chemotherapy treatment and identify a subgroup of patients with more adverse genomic tumour biology. A recent publication by Health Improvement Scotland (HIS) has updated guidance on use of the RS test for NHS Scotland [1].It suggests to limit its use to the intermediate risk PREDICT group. Our study shows the impact of the RS test in the low and high risk PREDICT groups. The implementation across Scotland has resulted in a notable shift in practice, leading to a significant reduction in chemotherapy administration in the setting of high risk PREDICT scores returning low risk RS. There has also been utility for the test in the low risk PREDICT group to detect a small subgroup with a high RS.
We have found the PR score to have a strong independent association with high risk RS. This finding was not evaluated by the key RS test papers, and the potential prognostic information provided by the PR score as a surrogate biomarker is an outstanding question that requires more research to validate
Tight-binding parameters for charge transfer along DNA
We systematically examine all the tight-binding parameters pertinent to
charge transfer along DNA. The molecular structure of the four DNA bases
(adenine, thymine, cytosine, and guanine) is investigated by using the linear
combination of atomic orbitals method with a recently introduced
parametrization. The HOMO and LUMO wavefunctions and energies of DNA bases are
discussed and then used for calculating the corresponding wavefunctions of the
two B-DNA base-pairs (adenine-thymine and guanine-cytosine). The obtained HOMO
and LUMO energies of the bases are in good agreement with available
experimental values. Our results are then used for estimating the complete set
of charge transfer parameters between neighboring bases and also between
successive base-pairs, considering all possible combinations between them, for
both electrons and holes. The calculated microscopic quantities can be used in
mesoscopic theoretical models of electron or hole transfer along the DNA double
helix, as they provide the necessary parameters for a tight-binding
phenomenological description based on the molecular overlap. We find that
usually the hopping parameters for holes are higher in magnitude compared to
the ones for electrons, which probably indicates that hole transport along DNA
is more favorable than electron transport. Our findings are also compared with
existing calculations from first principles.Comment: 15 pages, 3 figures, 7 table
Molecular characterization of two rocio flavivirus strains isolated during the encephalitis epidemic in são paulo state, brazil and the development of a one-step rt-pcr assay for diagnosis
Recoil Polarization for Delta Excitation in Pion Electroproduction
We measured angular distributions of recoil-polarization response functions
for neutral pion electroproduction for W=1.23 GeV at Q^2=1.0 (GeV/c)^2,
obtaining 14 separated response functions plus 2 Rosenbluth combinations; of
these, 12 have been observed for the first time. Dynamical models do not
describe quantities governed by imaginary parts of interference products well,
indicating the need for adjusting magnitudes and phases for nonresonant
amplitudes. We performed a nearly model-independent multipole analysis and
obtained values for Re(S1+/M1+)=-(6.84+/-0.15)% and Re(E1+/M1+)=-(2.91+/-0.19)%
that are distinctly different from those from the traditional Legendre analysis
based upon M1+ dominance and sp truncation.Comment: 5 pages, 2 figures, for PR
The supersymmetric prediction for the muon transverse polarization in the decay
The muon transverse polarization in the
decay will be measured at the level in forthcoming experiments. We
compare the phenomenological perspectives with the theoretical predictions in
supersymmetric extensions of the standard model. In the minimal extension,
CP-violating phases lead to a non-zero transverse polarization, that however is
too small to account for a positive experimental signal. The problems that one
encounters when departing from minimal assumptions are discussed. An observable
effect is possible if the hypothesis of R-parity conservation is relaxed, but
only at the price of assuming a very special pattern for the R-parity breaking
couplings.Comment: latex, 18 pages, 1 latex figur
Charm multiplicity and the branching ratios of inclusive charmless b quark decays in the general two-Higgs-doublet models
In the framework of general two-Higgs-doublet models, we calculate the
branching ratios of various inclusive charmless b decays by using the low
energy effective Hamiltonian including next-to-leading order QCD corrections,
and examine the current status and the new physics effects on the determination
of the charm multiplicity and semileptonic branching ratio .
Within the considered parameter space, the enhancement to the ratio due to the charged-Higgs penguins can be as large as a factor of 8 (3) in
the model III (II), while the ratio can be increased from
the standard model prediction of 2.49% to 4.91% (2.99%) in the model III (II).
Consequently, the value of and can be decreased simultaneously
in the model III. The central value of will be lowered slightly by
about 0.003, but the ratio can be reduced significantly from the
theoretical prediction of in the SM to , for GeV, respectively. We find that
the predicted and the measured now agree within roughly one
standard deviation after taking into account the effects of gluonic charged
Higgs penguins in the model III with a relatively light charged Higgs boson.Comment: 25 pages, Latex file, axodraw.sty, 6 figures. Final version to be
published in Phys.Rev.
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