4,346 research outputs found
Constraining Right-Handed Scale Through Kaon Mixing in SUSY Left-Right Model
We study flavor-changing neutral current and CP violations in the minimal
supersymmetric left-right model. We calculate the beyond-standard-model
contributions to the neutral kaon mixing and , and find
possible to have a numerical cancelation between the contributions from the
right-handed gauge boson and supersymmetric box diagram. With the cancelation,
the right-handed -boson mass scale can be lowered to about 2 TeV, well
within the search limit of LHC.Comment: 12 pages, new figures adde
Weak Microlensing
A nearby star having a near-transit of a galaxy will cause a time-dependent
weak lensing of the galaxy. Because the effect is small, we refer to this as
weak microlensing. This could provide a useful method to weigh low-mass stars
and brown dwarfs. We examine the feasibility of measuring masses in this way
and we find that a star causes measurable weak microlensing in a galaxy even at
10 Einstein radii away. Of order one magnitude I < 25 galaxy comes close enough
to one or other of the ~100 nearest stars per year.Comment: Accepted for publication in MNRAS (4 pages, 5 figures, 1 table
High prevalence of HPV 51 in an unvaccinated population and implications for HPV vaccines
Human papillomavirus (HPV) is detected in 99.7% of cervical cancers. Current vaccines target types 16 and 18. Prior to vaccination implementation, a prospective cohort study was conducted to determine baseline HPV prevalence in unvaccinated women in Wales; after HPV16 and HPV18, HPV 51 was found to be most prevalent. This study aimed to re-assess the unexpected high prevalence of HPV 51 and consider its potential for type-replacement. Two hundred HPV 51 positive samples underwent re-analysis by repeating the original methodology using HPV 51 GP5+/6+ PCR-enzyme immunoassay, and additionally a novel assay of HPV 51 E7 PCR. Data were correlated with age, social deprivation and cytology. Direct repeat of HPV 51 PCR-EIA identified 146/195 (75.0%) samples as HPV 51 positive; E7 PCR identified 166/195 (85.1%) samples as HPV 51 positive. HPV 51 prevalence increased with cytological grade. The prevalence of HPV 51 in the pre-vaccinated population was truly high. E7 DNA assays may offer increased specificity for HPV genotyping. Cross-protection of current vaccines against less-prevalent HPV types warrants further study. This study highlights the need for longitudinal investigation into the prevalence of non-vaccine HPV types, especially those phylogenetically different to vaccine types for potential type-replacement. Ongoing surveillance will inform future vaccines
Strangeness in the proton and N*(1535)
The newest progress on the study of the strangeness in the proton and in the
lowest negative parity nucleon excited state is reviewed.
Implications on the internal quark structure of the proton, and
other baryons are discussed. The diquark cluster picture for the 5-quark
components in baryons gives a natural explanation not only to the empirical
indications for a positive strangeness magnetic moment and positive
strangeness radius of the proton but also the longstanding mass-reverse problem
of , and resonances as well as the
unusual decay pattern of the resonance. Evidence for possible
existence of 's SU(3) nonet partners in this picture is
pointed out, and suggestion is made to search for these hyperon excited
states under the well known , and
peaks in various reactions.Comment: 6 pages, 2 figures, Plenary talk at 18th International IUPAP
Conference on Few-Body Problems in Physics August 21-26. 2006 Santos SP
Brazil; to be published in Nuclear Physics
Bounds on R-Parity Violating Parameters from Fermion EDM's
We study one-loop contributions to the fermion electric dipole moments in the
Minimal Supersymmetric Standard Model with explicit R-parity violating
interactions. We obtain new individual bounds on R-parity violating Yukawa
couplings and put more stringent limits on certain parameters than those
obtained previously.Comment: 16 pages, LaTe
Alemtuzumab pre-conditioning with tacrolimus monotherapy in pediatric renal transplantation
We employed antibody pre-conditioning with alemtuzumab and posttransplant immunosuppression with low-dose tacrolimus monotherapy in 26 consecutive pediatric kidney transplant recipients between January 2004 and December 2005. Mean recipient age was 10.7 ± 5.8 years, 7.7% were undergoing retransplantation, and 3.8% were sensitized, with a PRA >20%. Mean donor age was 32.8 ± 9.2 years. Living donors were utilized in 65% of the transplants. Mean cold ischemia time was 27.6 ± 6.4 h. The mean number of HLA mismatches was 3.3 ± 1.3. Mean follow-up was 25 ± 8 months. One and 2 year patient survival was 100% and 96%. One and 2 year graft survival was 96% and 88%. Mean serum creatinine was 1.1 ± 0.6 mg/dL, and calculated creatinine clearance was 82.3 ± 29.4 mL/min/1.73 m 2. The incidence of pre-weaning acute rejection was 11.5%; the incidence of delayed graft function was 7.7%. Eighteen (69%) of the children were tapered to spaced tacrolimus monotherapy, 10.5 ± 2.2 months after transplantation. The incidence of CMV, PTLD and BK virus was 0%; the incidence of posttransplant diabetes was 7.7%. Although more follow-up is clearly needed, antibody pre-conditioning with alemtuzumab and tacrolimus monotherapy may be a safe and effective regimen in pediatric renal transplantation. © 2007 The Authors
Delayed Perforation of the Right Ventricular Wall by a Single Standard-Caliber Implantable Cardioverter-Defibrillator Lead Detected by Multidetector Computed Tomography
We present an unusual case of a delayed right ventricular perforation by a single standard-caliber implantable cardioverter-defibrillator lead, which manifested 14 days after implantation. Multidetector computed tomography could clearly display the lead perforation, and allow for identification of the associated sequelae such as pericardial effusion and planning the lead extraction strategy
Constraints on the Phase Plane of the Dark Energy Equation of State
Classification of dark energy models in the plane of w and w', where w is the
dark energy equation of state and w' its time-derivative in units of the Hubble
time, has been studied in the literature. We take the current SN Ia, CMB and
BAO data, invoke a widely used parametrization of the dark energy equation of
state, and obtain the constraints on the w -w' plane. We find that dark energy
models including the cosmological constant, phantom, non-phantom barotropic
fluids, and monotonic up-rolling quintessence are ruled out at the 68.3%
confidence level based on the current observational data. Down-rolling
quintessence, including the thawing and the freezing models, is consistent with
the current observations. All the above-mentioned models are still consistent
with the data at the 95.4% confidence level.Comment: 14 pages, 5 figures, "Test of the method" added in Sec. 4 in v
The Algorithmic Origins of Life
Although it has been notoriously difficult to pin down precisely what it is
that makes life so distinctive and remarkable, there is general agreement that
its informational aspect is one key property, perhaps the key property. The
unique informational narrative of living systems suggests that life may be
characterized by context-dependent causal influences, and in particular, that
top-down (or downward) causation -- where higher-levels influence and constrain
the dynamics of lower-levels in organizational hierarchies -- may be a major
contributor to the hierarchal structure of living systems. Here we propose that
the origin of life may correspond to a physical transition associated with a
shift in causal structure, where information gains direct, and
context-dependent causal efficacy over the matter it is instantiated in. Such a
transition may be akin to more traditional physical transitions (e.g.
thermodynamic phase transitions), with the crucial distinction that determining
which phase (non-life or life) a given system is in requires dynamical
information and therefore can only be inferred by identifying causal
architecture. We discuss some potential novel research directions based on this
hypothesis, including potential measures of such a transition that may be
amenable to laboratory study, and how the proposed mechanism corresponds to the
onset of the unique mode of (algorithmic) information processing characteristic
of living systems.Comment: 13 pages, 1 tabl
CP and Lepton-Number Violation in GUT Neutrino Models with Abelian Flavour Symmetries
We study the possible magnitudes of CP and lepton-number-violating quantities
in specific GUT models of massive neutrinos with different Abelian flavour
groups, taking into account experimental constraints and requiring successful
leptogenesis. We discuss SU(5) and flipped SU(5) models that are consistent
with the present data on neutrino mixing and upper limits on the violations of
charged-lepton flavours and explore their predictions for the CP-violating
oscillation and Majorana phases. In particular, we discuss string-derived
flipped SU(5) models with selection rules that modify the GUT structure and
provide additional constraints on the operators, which are able to account for
the magnitudes of some of the coefficients that are often set as arbitrary
parameters in generic Abelian models.Comment: 30 pages, 6 figure
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