8,860 research outputs found
Kaplan-Narayanan-Neuberger lattice fermions pass a perturbative test
We test perturbatively a recent scheme for implementing chiral fermions on
the lattice, proposed by Kaplan and modified by Narayanan and Neuberger, using
as our testing ground the chiral Schwinger model. The scheme is found to
reproduce the desired form of the effective action, whose real part is gauge
invariant and whose imaginary part gives the correct anomaly in the continuum
limit, once technical problems relating to the necessary infinite extent of the
extra dimension are properly addressed. The indications from this study are
that the Kaplan--Narayanan--Neuberger (KNN) scheme has a good chance at being a
correct lattice regularization of chiral gauge theories.Comment: LaTeX 18 pages, 3 figure
Anxiety and depression with neurogenesis defects in exchange protein directly activated by cAMP 2-deficient mice are ameliorated by a selective serotonin reuptake inhibitor, Prozac
Intracellular cAMP and serotonin are important modulators of anxiety and depression. Fluoxetine, a selective serotonin reuptake inhibitor (SSRI) also known as Prozac, is widely used against depression, potentially by activating cAMP response element-binding protein (CREB) and increasing brain-derived neurotrophic factor (BDNF) through protein kinase A (PKA). However, the role of Epac1 and Epac2 (Rap guanine nucleotide exchange factors, RAPGEF3 and RAPGEF4, respectively) as potential downstream targets of SSRI/cAMP in mood regulations is not yet clear. Here, we investigated the phenotypes of Epac1 (Epac1− / −) or Epac2 (Epac2− / −) knockout mice by comparing them with their wild-type counterparts. Surprisingly, Epac2− / − mice exhibited a wide range of mood disorders, including anxiety and depression with learning and memory deficits in contextual and cued fear-conditioning tests without affecting Epac1 expression or PKA activity. Interestingly, rs17746510, one of the three single-nucleotide polymorphisms (SNPs) in RAPGEF4 associated with cognitive decline in Chinese Alzheimer’s disease (AD) patients, was significantly correlated with apathy and mood disturbance, whereas no significant association was observed between RAPGEF3 SNPs and the risk of AD or neuropsychiatric inventory scores. To further determine the detailed role of Epac2 in SSRI/serotonin/cAMP-involved mood disorders, we treated Epac2− / − mice with a SSRI, Prozac. The alteration in open field behavior and impaired hippocampal cell proliferation in Epac2− / − mice were alleviated by Prozac. Taken together, Epac2 gene polymorphism is a putative risk factor for mood disorders in AD patients in part by affecting the hippocampal neurogenesis.published_or_final_versio
CACNA1C polymorphisms Impact Cognitive Recovery in Patients with Bipolar Disorder in a Six-week Open-label Trial
published_or_final_versio
Universal Statistics of the Scattering Coefficient of Chaotic Microwave Cavities
We consider the statistics of the scattering coefficient S of a chaotic
microwave cavity coupled to a single port. We remove the non-universal effects
of the coupling from the experimental S data using the radiation impedance
obtained directly from the experiments. We thus obtain the normalized, complex
scattering coefficient whose Probability Density Function (PDF) is predicted to
be universal in that it depends only on the loss (quality factor) of the
cavity. We compare experimental PDFs of the normalized scattering coefficients
with those obtained from Random Matrix Theory (RMT), and find excellent
agreement. The results apply to scattering measurements on any wave chaotic
system.Comment: 10 pages, 8 Figures, Fig.7 in Color, Submitted to Phys. Rev.
On the Usability of Probably Approximately Correct Implication Bases
We revisit the notion of probably approximately correct implication bases
from the literature and present a first formulation in the language of formal
concept analysis, with the goal to investigate whether such bases represent a
suitable substitute for exact implication bases in practical use-cases. To this
end, we quantitatively examine the behavior of probably approximately correct
implication bases on artificial and real-world data sets and compare their
precision and recall with respect to their corresponding exact implication
bases. Using a small example, we also provide qualitative insight that
implications from probably approximately correct bases can still represent
meaningful knowledge from a given data set.Comment: 17 pages, 8 figures; typos added, corrected x-label on graph
Patient Perception of Physician Attire Before and After Disclosure of the Risks of Microbial Contamination
Background: The white coat is traditionally considered to be the appropriate attire for physicians but it may also be contaminated with microbes and act as a potential source of infection. We aimed to study patients’ acceptance of physicians’ attire, their underlying reasons, and their reactions to an educational intervention with regards to the risks of contamination. Methods: We conducted a voluntary quesÂtionnaire survey at a university teaching hospital in Hong Kong from February to July 2012. 262 patient-responses from adult inpatients and outpatients across various specialties were analysed. Results: White coats were highly favoured (90.8%) when compared with scrubs (22.1%), smart casual (7.6%) and formal (7.3%) wears. ’Professional image’ and ‘ease of identification’ were the main attributes of the white coat. Most patients (92.2%) would prefer doctors washing their white coats every few days, whilst 80.9% believed that doctors were actually doing so. After patients were informed of the potential risk of microbial contamination, white coats remained as the most favoured attire (66.4%), but with scrubs doubling in popularity (45.8%). Smart casual (9.2%) and formal attire (4.6%) remain the least accepted. Conclusion: Despite cross-infections being a significant concern within the healthcare environments, patients’ predominant acceptance and perceived attributes towards the white coat were maintained after an educational intervention on the risks of microbial contamination
Pulse-shape discrimination between electron and nuclear recoils in a NaI(Tl) crystal
We report on the response of a high light-output NaI(Tl) crystal to nuclear
recoils induced by neutrons from an Am-Be source and compare the results with
the response to electron recoils produced by Compton scattered 662 keV
-rays from a Cs source. The measured pulse-shape discrimination
(PSD) power of the NaI(Tl) crystal is found to be significantly improved
because of the high light output of the NaI(Tl) detector. We quantify the PSD
power with a quality factor and estimate the sensitivity to the interaction
rate for weakly interacting massive particles (WIMPs) with nucleons, and the
result is compared with the annual modulation amplitude observed by the
DAMA/LIBRA experiment. The sensitivity to spin-independent WIMP-nucleon
interactions based on 100 kgyear of data from NaI detectors is estimated
with simulated experiments, using the standard halo model.Comment: 11page
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