1,787 research outputs found
Profiling time course expression of virus genes---an illustration of Bayesian inference under shape restrictions
There have been several studies of the genome-wide temporal transcriptional
program of viruses, based on microarray experiments, which are generally useful
in the construction of gene regulation network. It seems that biological
interpretations in these studies are directly based on the normalized data and
some crude statistics, which provide rough estimates of limited features of the
profile and may incur biases. This paper introduces a hierarchical Bayesian
shape restricted regression method for making inference on the time course
expression of virus genes. Estimates of many salient features of the expression
profile like onset time, inflection point, maximum value, time to maximum
value, area under curve, etc. can be obtained immediately by this method.
Applying this method to a baculovirus microarray time course expression data
set, we indicate that many biological questions can be formulated
quantitatively and we are able to offer insights into the baculovirus biology.Comment: Published in at http://dx.doi.org/10.1214/09-AOAS258 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Simple Models of the Protein Folding Problem
The protein folding problem has attracted an increasing attention from
physicists. The problem has a flavor of statistical mechanics, but possesses
the most common feature of most biological problems -- the profound effects of
evolution. I will give an introduction to the problem, and then focus on some
recent work concerning the so-called ``designability principle''. The
designability of a structure is measured by the number of sequences that have
that structure as their unique ground state. Structures differ drastically in
terms of their designability; highly designable structures emerge with a number
of associated sequences much larger than the average. These highly designable
structures 1) possess ``proteinlike'' secondary structures and motifs, 2) are
thermodynamically more stable, and 3) fold faster than other structures. These
results suggest that protein structures are selected in nature because they are
readily designed and stable against mutations, and that such selection
simultaneously leads to thermodynamic stability and foldability. According to
this picture, a key to the protein folding problem is to understand the
emergence and the properties of the highly designable structures.Comment: 21 pages, 14 figures. Invited talk at Dynamics Days Asian Pacific,
Hong Kong, July 13-16, 1999. To appear in Physica
Enhanced photo-excitation and angular-momentum imprint of gray excitons in WSe monolayers by spin-orbit-coupled vector vortex beams
A light beam can be spatially structured in the complex amplitude to possess
orbital angular momentum (OAM), which introduces a new degree of freedom
alongside the intrinsic spin angular momentum (SAM) associated with circular
polarization. Moreover, super-imposing two twisted lights with distinct SAM and
OAM produces a vector vortex beam (VVB) in non-separable states where not only
complex amplitude but also polarization are spatially structured and entangled
with each other. In addition to the non-separability, the SAM and OAM in a VVB
are intrinsically coupled by the optical spin-orbit interaction and constitute
the profound spin-orbit physics in photonics. In this work, we present a
comprehensive theoretical investigation, implemented on the first-principles
base, of the intriguing light-matter interaction between VVBs and WSe
monolayers (WSe-MLs), one of the best-known and promising two-dimensional
(2D) materials in optoelectronics dictated by excitons, encompassing bright
exciton (BX) as well as various dark excitons (DXs). One of the key findings of
our study is the substantial enhancement of the photo-excitation of gray
excitons (GXs), a type of spin-forbidden dark exciton, in a WSe-ML through
the utilization of a twisted light that possesses a longitudinal field
associated with the optical spin-orbit interaction. Our research demonstrates
that a spin-orbit-coupled VVB surprisingly allows for the imprinting of the
carried optical information onto gray excitons in 2D materials, which is robust
against the decoherence mechanisms in materials. This observation suggests a
promising method for deciphering the transferred angular momentum from
structured lights to excitons
Current and state of the art on the electrophysiologic characteristics and catheter ablation of arrhythmogenic right ventricular dysplasia/cardiomyopathy
AbstractArrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is an inherited genetic disease caused by defective desmosomal proteins, and it has typical histopathological features characterized by predominantly progressive fibro-fatty infiltration of the right ventricle. Clinical presentations of ARVD/C vary from syncope, progressive heart failure (HF), ventricular tachyarrhythmias, and sudden cardiac death (SCD). The 2010 modified Task Force criteria were established to facilitate the recognition and diagnosis of ARVD/C. An implantable cardiac defibrillator (ICD) remains to be the cornerstone in prevention of SCD in patients fulfilling the diagnosis of definite ARVD/C, especially among ARVD/C patients with syncope, hemodynamically unstable ventricular tachycardia (VT), ventricular fibrillation, and aborted SCD. Further risk stratification is clinically valuable in the management of patients with borderline or possible ARVD/C and mutation carriers of family members. However, given the entity of heterogeneous penetrance and non-uniform phenotypes, the standardization of clinical practice guidelines for at-risk individuals will be the next frontier to breakthrough.Antiarrhythmic drugs are prescribed frequently to patients experiencing frequent ventricular tachyarrhythmias and/or appropriate ICD shocks. Amiodarone is the recommended drug of choice. Radiofrequency catheter ablation (RFCA) has been demonstrated to effectively eliminate the drug-refractory VT in patients with ARVD/C. However, the efficacy and clinical prognosis of RFCA via endocardial approach alone was disappointing prior to the era of epicardial approach. In recent years, it has been proven that the integration of endocardial and epicardial ablation by targeting the critical isthmus or eliminating abnormal electrograms within the diseased substrates could yield higher acute success and lower recurrence of ventricular tachyarrhythmias during long-term follow-up. Heart transplantation is the final option for patients with extensive disease, biventricular HF with uncontrollable hemodynamic compromise, and refractory ventricular tachyarrhythmias despite aggressive medical and ablation therapies
Anatomical features, fiber morphological, physical and mechanical properties of three years old new hybrid Paulownia: green Paulownia
Objective: Green Paulownia (hybridization of Paulownia elongata × Paulownia fotunei and tropical Paulownia spp.) is new hybrid claimed as one of the fast-growing woody plants with the high potential as a fiber material or lignocellulosic material. The material for this study originates from the area of Nanning in China.
Methodology: Cell morphology and anatomical appearances were observed and evaluated under the image analysis system (Leica DMLS). Physical and mechanical properties were evaluated based on the American Society for Testing and Materials (ASTM) standards.
Results: From the results, average value of the mean fiber length was 0.905 mm, mean fiber length 34.59 μm, lumen thickness 26.80 μm and cell wall thickness 3.89 μm. Fiber dimensions of green Paulownia are in the normal range for hardwoods. The physical and mechanical properties of 3 years old green Paulownia have similar properties than those 7-11 years old Paulownia published in China.
Conclusion: The 3 years old green Paulownia timbers can be used as materials for furniture
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