318 research outputs found
The Higgs as a Probe of Supersymmetric Extra Sectors
We present a general method for calculating the leading contributions to h ->
gg and h -> gamma gamma in models where the Higgs weakly mixes with a nearly
supersymmetric extra sector. Such mixing terms can play an important role in
raising the Higgs mass relative to the value expected in the MSSM. Our method
applies even when the extra sector is strongly coupled, and moreover does not
require a microscopic Lagrangian description. Using constraints from holomorphy
we fix the leading parametric form of the contributions to these Higgs
processes, including the Higgs mixing angle dependence, up to an overall
coefficient. Moreover, when the Higgs is the sole source of mass for a
superconformal sector, we show that even this coefficient is often calculable.
For appropriate mixing angles, the contribution of the extra states to h -> gg
and h -> gamma gamma can vanish. We also discuss how current experimental
limits already lead to non-trivial constraints on such models. Finally, we
provide examples of extra sectors which satisfy the requirements necessary to
use the holomorphic approximation.Comment: v4: 34 pages, 2 figures, typo corrected and clarification adde
Should mechanical dyssynchrony be assessed in patients with implantable cardioverter-defibrillators?
Cardiac Dysfunction and Arrhythmia
Reduced Physiological Complexity in Robust Elderly Adults with the APOE ε4 Allele
BACKGROUND:It is unclear whether the loss of physiological complexity during the aging process is due to genetic variations. The APOE gene has been studied extensively in regard to its relationship with aging-associated medical illness. We hypothesize that diminished physiological complexity, as measured by heart rate variability, is influenced by polymorphisms in the APOE allele among elderly individuals. METHODOLOGY/PRINCIPAL FINDINGS:A total of 102 robust, non-demented, elderly subjects with normal functions of daily activities participated in this study (97 males and 5 females, aged 79.2+/-4.4 years, range 72-92 years). Among these individuals, the following two APOE genotypes were represented: epsilon4 non-carriers (n = 87, 85.3%) and epsilon4 carriers (n = 15, 14.7%). Multi-scale entropy (MSE), an analysis used in quantifying complexity for nonlinear time series, was employed to analyze heart-rate dynamics. Reduced physiological complexity, as measured by MSE, was significantly associated with the presence of the APOE epsilon4 allele in healthy elderly subjects, as compared to APOE epsilon4 allele non-carriers (24.6+/-5.5 versus 28.9+/-5.2, F = 9.429, p = 0.003, respectively). CONCLUSIONS/SIGNIFICANCE:This finding suggests a role for the APOE gene in the diminished physiological complexity seen in elderly populations
Evidence for F(uzz) Theory
We show that in the decoupling limit of an F-theory compactification, the
internal directions of the seven-branes must wrap a non-commutative four-cycle
S. We introduce a general method for obtaining fuzzy geometric spaces via toric
geometry, and develop tools for engineering four-dimensional GUT models from
this non-commutative setup. We obtain the chiral matter content and Yukawa
couplings, and show that the theory has a finite Kaluza-Klein spectrum. The
value of 1/alpha_(GUT) is predicted to be equal to the number of fuzzy points
on the internal four-cycle S. This relation puts a non-trivial restriction on
the space of gauge theories that can arise as a limit of F-theory. By viewing
the seven-brane as tiled by D3-branes sitting at the N fuzzy points of the
geometry, we argue that this theory admits a holographic dual description in
the large N limit. We also entertain the possibility of constructing string
models with large fuzzy extra dimensions, but with a high scale for quantum
gravity.Comment: v2: 66 pages, 3 figures, references and clarifications adde
Children with cerebral palsy exhibit greater and more regular postural sway than typically developing children
Following recent advances in the analysis of centre-of-pressure (COP) recordings, we examined the structure of COP trajectories in ten children (nine in the analyses) with cerebral palsy (CP) and nine typically developing (TD) children while standing quietly with eyes open (EO) and eyes closed (EC) and with concurrent visual COP feedback (FB). In particular, we quantified COP trajectories in terms of both the amount and regularity of sway. We hypothesised that: (1) compared to TD children, CP children exhibit a greater amount of sway and more regular sway and (2) concurrent visual feedback (creating an external functional context for postural control, inducing a more external focus of attention) decreases both the amount of sway and sway regularity in TD and CP children alike, while closing the eyes has opposite effects. The data were largely in agreement with both hypotheses. Compared to TD children, the amount of sway tended to be larger in CP children, while sway was more regular. Furthermore, the presence of concurrent visual feedback resulted in less regular sway compared to the EO and EC conditions. This effect was less pronounced in the CP group where posturograms were most regular in the EO condition rather than in the EC condition, as in the control group. Nonetheless, we concluded that CP children might benefit from therapies involving postural tasks with an external functional context for postural control
Estimation of imaging biomarker's progression in post-infarct patients using cross-sectional data
International audienceMany uncertainties remain about the relation between post-infarct scars and ventricular arrhythmia. Most post-infarct patients suffer scar-related arrhythmia several years after the infarct event suggesting that scar remodeling is a process that might require years until the affected tissue becomes arrhythmogenic. In clinical practice, a simple time-based rule is often used to assess risk and stratify patients. In other cases, left ventricular ejection fraction (LVEF) impairment is also taken into account but it is known to be suboptimal. More information is needed to better stratify patients and prescribe appropriate individualized treatments. In this paper we propose to use probabilistic disease progression modeling to obtain an image-based data-driven description of the in-farct maturation process. Our approach includes monotonic constraints in order to impose a regular behaviour on the biomarkers' trajectories. 49 post-MI patients underwent Computed Tomography (CT) and Late Gadolinium Enhanced Cardiac Magnetic Resonance (LGE-CMR) scans. Image-derived biomarkers were computed such as LVEF, LGE-CMR scar volume, fat volume, and size of areas with a different degree of left ven-tricular wall narrowing, from moderate to severe. We show that the model is able to estimate a plausible progression of post-infarct scar maturation. According to our results there is a progressive thinning process observable only with CT imaging; intramural fat appears in a late stage; LGE-CMR scar volume almost does not change and LVEF slightly changes during the scar maturation process
Flavour in supersymmetry: horizontal symmetries or wave function renormalisation
We compare theoretical and experimental predictions of two main classes of
models addressing fermion mass hierarchies and flavour changing neutral
currents (FCNC) effects in supersymmetry: Froggatt-Nielsen (FN) U(1) gauged
flavour models and Nelson-Strassler/extra dimensional models with hierarchical
wave functions for the families. We show that whereas the two lead to identical
predictions in the fermion mass matrices, the second class generates a stronger
suppression of FCNC effects. We prove that, whereas at first sight the FN setup
is more constrained due to anomaly cancelation conditions, imposing unification
of gauge couplings in the second setup generates conditions which precisely
match the mixed anomaly constraints in the FN setup. Finally, we provide an
economical extra dimensional realisation of the hierarchical wave functions
scenario in which the leptonic FCNC can be efficiently suppressed due to the
strong coupling (CFT) origin of the electron mass.Comment: 23 page
New physics searches at near detectors of neutrino oscillation experiments
We systematically investigate the prospects of testing new physics with tau
sensitive near detectors at neutrino oscillation facilities. For neutrino beams
from pion decay, from the decay of radiative ions, as well as from the decays
of muons in a storage ring at a neutrino factory, we discuss which effective
operators can lead to new physics effects. Furthermore, we discuss the present
bounds on such operators set by other experimental data currently available.
For operators with two leptons and two quarks we present the first complete
analysis including all relevant operators simultaneously and performing a
Markov Chain Monte Carlo fit to the data. We find that these effects can induce
tau neutrino appearance probabilities as large as O(10^{-4}), which are within
reach of forthcoming experiments. We highlight to which kind of new physics a
tau sensitive near detector would be most sensitive.Comment: 20 pages, 2 figures, REVTeX
Parasympathetic Activity and Blood Catecholamine Responses Following a Single Partial-Body Cryostimulation and a Whole-Body Cryostimulation
The aim of this study was to compare the effects of a single whole-body cryostimulation (WBC) and a partial-body cryostimulation (PBC) (i.e., not exposing the head to cold) on indices of parasympathetic activity and blood catecholamines. Two groups of 15 participants were assigned either to a 3-min WBC or PBC session, while 10 participants constituted a control group (CON) not receiving any cryostimulation. Changes in thermal, physiological and subjective variables were recorded before and during the 20-min after each cryostimulation. According to a qualitative statistical analysis, an almost certain decrease in skin temperature was reported for all body regions immediately after the WBC (mean decrease±90% CL, -13.7±0.7°C) and PBC (-8.3±0.3°C), which persisted up to 20-min after the session. The tympanic temperature almost certainly decreased only after the WBC session (-0.32±0.04°C). Systolic and diastolic blood pressures were very likely increased after the WBC session, whereas these changes were trivial in the other groups. In addition, heart rate almost certainly decreased after PBC (-10.9%) and WBC (-15.2%) sessions, in a likely greater proportion for WBC compared to PBC. Resting vagal-related heart rate variability indices (the root-mean square difference of successive normal R-R intervals, RMSSD, and high frequency band, HF) were very likely increased after PBC (RMSSD: +54.4%, HF: +138%) and WBC (RMSSD:
+85.2%, HF: +632%) sessions without any marked difference between groups. Plasma norepinephrine concentrations were likely to very likely increased after PBC (+57.4%) and WBC (+76.2%), respectively. Finally, cold and comfort sensations were almost certainly altered after WBC and PBC, sensation of discomfort being likely more pronounced after WBC than PBC. Both acute cryostimulation techniques effectively stimulated the autonomic nervous system (ANS), with a predominance of parasympathetic tone activation. The results of this study also suggest that a whole-body cold exposure induced a larger stimulation of the ANS compared to partial-body cold exposure
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