694 research outputs found
On theories of enhanced CP violation in B_s,d meson mixing
The DO collaboration has measured a deviation from the standard model (SM)
prediction in the like sign dimuon asymmetry in semileptonic b decay with a
significance of 3.2 sigma. We discuss how minimal flavour violating (MFV)
models with multiple scalar representations can lead to this deviation through
tree level exchanges of new MFV scalars. We review how the two scalar doublet
model can accommodate this result and discuss some of its phenomenology. Limits
on electric dipole moments suggest that in this model the coupling of the
charged scalar to the right handed u-type quarks is suppressed while its
coupling to the d-type right handed quarks must be enhanced. We construct an
extension of the MFV two scalar doublet model where this occurs naturally.Comment: 10 pages, 7 figures, v3 final JHEP versio
Shortcuts to adiabaticity in a time-dependent box
A method is proposed to drive an ultrafast non-adiabatic dynamics of an
ultracold gas trapped in a box potential. The resulting state is free from
spurious excitations associated with the breakdown of adiabaticity, and
preserves the quantum correlations of the initial state up to a scaling factor.
The process relies on the existence of an adiabatic invariant and the inversion
of the dynamical self-similar scaling law dictated by it. Its physical
implementation generally requires the use of an auxiliary expulsive potential
analogous to those used in soliton control. The method is extended to a broad
family of many-body systems. As illustrative examples we consider the ultrafast
expansion of a Tonks-Girardeau gas and of Bose-Einstein condensates in
different dimensions, where the method exhibits an excellent robustness against
different regimes of interactions and the features of an experimentally
realizable box potential.Comment: 6 pp, 4 figures, typo in Eq. (6) fixe
Theoretical and Phenomenological Constraints on Form Factors for Radiative and Semi-Leptonic B-Meson Decays
We study transition form factors for radiative and rare semi-leptonic B-meson
decays into light pseudoscalar or vector mesons, combining theoretical
constraints and phenomenological information from Lattice QCD, light-cone sum
rules, and dispersive bounds. We pay particular attention to form factor
parameterisations which are based on the so-called series expansion, and study
the related systematic uncertainties on a quantitative level. In this context,
we also provide the NLO corrections to the correlation function between two
flavour-changing tensor currents, which enters the unitarity constraints for
the coefficients in the series expansion.Comment: 52 pages; v2: normalization error in (29ff.) corrected, conclusion
about relevance of unitarity bounds modified; form factor fits unaffected;
references added; v3: discussion on truncation of series expansion added,
matches version to be published in JHEP; v4: corrected typos in Tables 5 and
Bell Correlations and the Common Future
Reichenbach's principle states that in a causal structure, correlations of
classical information can stem from a common cause in the common past or a
direct influence from one of the events in correlation to the other. The
difficulty of explaining Bell correlations through a mechanism in that spirit
can be read as questioning either the principle or even its basis: causality.
In the former case, the principle can be replaced by its quantum version,
accepting as a common cause an entangled state, leaving the phenomenon as
mysterious as ever on the classical level (on which, after all, it occurs). If,
more radically, the causal structure is questioned in principle, closed
space-time curves may become possible that, as is argued in the present note,
can give rise to non-local correlations if to-be-correlated pieces of classical
information meet in the common future --- which they need to if the correlation
is to be detected in the first place. The result is a view resembling Brassard
and Raymond-Robichaud's parallel-lives variant of Hermann's and Everett's
relative-state formalism, avoiding "multiple realities."Comment: 8 pages, 5 figure
Fungal iron availability during deep seated candidiasis is defined by a complex interplay involving systemic and local events
Peer reviewedPublisher PD
Climate Change and invasibility of the Antarctic benthos
Benthic communities living in shallow-shelf habitats in Antarctica (<100-m depth) are archaic in their structure and function. Modern predators, including fast-moving, durophagous (skeleton-crushing) bony fish, sharks, and crabs, are rare or absent; slow-moving invertebrates are the top predators; and epifaunal suspension feeders dominate many soft substratum communities. Cooling temperatures beginning in the late Eocene excluded durophagous predators, ultimately resulting in the endemic living fauna and its unique food-web structure. Although the Southern Ocean is oceanographically isolated, the barriers to biological invasion are primarily physiological rather than geographic. Cold temperatures impose limits to performance that exclude modern predators. Global warming is now removing those physiological barriers, and crabs are reinvading Antarctica. As sea temperatures continue to rise, the invasion of durophagous predators will modernize the shelf benthos and erode the indigenous character of marine life in Antarctica
Full-length Ebola glycoprotein accumulates in the endoplasmic reticulum
The Filoviridae family comprises of Ebola and Marburg viruses, which are known to cause lethal hemorrhagic fever. However, there is no effective anti-viral therapy or licensed vaccines currently available for these human pathogens. The envelope glycoprotein (GP) of Ebola virus, which mediates entry into target cells, is cytotoxic and this effect maps to a highly glycosylated mucin-like region in the surface subunit of GP (GP1). However, the mechanism underlying this cytotoxic property of GP is unknown. To gain insight into the basis of this GP-induced cytotoxicity, HEK293T cells were transiently transfected with full-length and mucin-deleted (Δmucin) Ebola GP plasmids and GP localization was examined relative to the nucleus, endoplasmic reticulum (ER), Golgi, early and late endosomes using deconvolution fluorescent microscopy. Full-length Ebola GP was observed to accumulate in the ER. In contrast, GPΔmucin was uniformly expressed throughout the cell and did not localize in the ER. The Ebola major matrix protein VP40 was also co-expressed with GP to investigate its influence on GP localization. GP and VP40 co-expression did not alter GP localization to the ER. Also, when VP40 was co-expressed with the nucleoprotein (NP), it localized to the plasma membrane while NP accumulated in distinct cytoplasmic structures lined with vimentin. These latter structures are consistent with aggresomes and may serve as assembly sites for filoviral nucleocapsids. Collectively, these data suggest that full-length GP, but not GPΔmucin, accumulates in the ER in close proximity to the nuclear membrane, which may underscore its cytotoxic property
Multiple Causes for Delay in Arrival at Hospital in Acute Stroke Patients in Aydin, Turkey
This descriptive, hospital-based study, performed in western Turkey, was designed to assess the level of pre-hospital delay and reasons for such delay in acute stroke patients, taking into consideration certain factors such as socioeconomic status, availability of transport options at onset of symptoms. Data were collected from hospital records, and a questionnaire was administered that included questions about socio-demographics, self-reported risk factors and questions related to hospital arrival. The rate of patients arriving at the hospital more than 3 hours after symptom onset was found to be 31.6% for this study. Approximately 1/3 of patients delayed going to the hospital because they were waiting for symptoms to go away while 1/3 of patients were not aware of the importance of seeking immediate medical help. There was a significant relationship between the use of ambulance transportation and length of time before arrival at the hospitals, though there was no statistically significantly relationship between the existence of stroke risk factors and hospital arrival delay. These results will likely be helpful to health care decision makers as they develop a model for stroke health care and community based training
Protective Efficacy of Neutralizing Monoclonal Antibodies in a Nonhuman Primate Model of Ebola Hemorrhagic Fever
Ebola virus (EBOV) is the causative agent of severe hemorrhagic fever in primates, with human case fatality rates up to 90%. Today, there is neither a licensed vaccine nor a treatment available for Ebola hemorrhagic fever (EHF). Single monoclonal antibodies (MAbs) specific for Zaire ebolavirus (ZEBOV) have been successfully used in passive immunization experiments in rodent models, but have failed to protect nonhuman primates from lethal disease. In this study, we used two clones of human-mouse chimeric MAbs (ch133 and ch226) with strong neutralizing activity against ZEBOV and evaluated their protective potential in a rhesus macaque model of EHF. Reduced viral loads and partial protection were observed in animals given MAbs ch133 and ch226 combined intravenously at 24 hours before and 24 and 72 hours after challenge. MAbs circulated in the blood of a surviving animal until virus-induced IgG responses were detected. In contrast, serum MAb concentrations decreased to undetectable levels at terminal stages of disease in animals that succumbed to infection, indicating substantial consumption of these antibodies due to virus replication. Accordingly, the rapid decrease of serum MAbs was clearly associated with increased viremia in non-survivors. Our results indicate that EBOV neutralizing antibodies, particularly in combination with other therapeutic strategies, might be beneficial in reducing viral loads and prolonging disease progression during EHF
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