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Search Results: 1 - 10 of 130562 matches for " Eva Y Chen "
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The PEST sequence does not contribute to the stability of the cystic fibrosis transmembrane conductance regulator
Eva Y Chen, David M Clarke
BMC Biochemistry , 2002, DOI: 10.1186/1471-2091-3-29
Abstract: Using a web-based algorithm, PESTFind, we found a PEST sequence in the regulatory (R) domain of CFTR. The PEST sequence is found in many short-lived eukaryotic proteins and plays a role in their degradation. To determine its role in the stability and degradation of misprocessed CFTR, we introduced a number of site-directed mutations into the PEST sequence in the cDNA of ΔF508 CFTR, the most prevalent misprocessed mutation found in CF patients. Analysis of these mutants showed that the disruption of the PEST sequence plays a minor role in the degradation of the CFTR mutants. Multiple mutations to the PEST sequence within the R domain of CFTR inhibit maturation of CFTR and prevent the formation of a 100 kDa degradation product. The mutations, however, do not improve the stability of the mutant ΔF508 CFTR.These observations show that disruption of the structure of the R domain of CFTR can inhibit maturation of the protein and that the predicted PEST sequence plays no significant role in the degradation of CFTR.Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene cause cystic fibrosis (CF), the most prevalent fatal recessive genetic disease in the Caucasian population [1]. CFTR is a polytopic integral membrane protein synthesized in the endoplasmic reticulum (ER) and normally expressed on the apical surface of epithelial cells where it functions as a phosphorylation-stimulated and ATP-dependent chloride channel. The majority of CF patients express processing defective CFTRs that fail to mature to the cell surface; instead, the processing defective CFTRs are retained in the ER and are targeted for rapid degradation [2,3].The retention of processing defective CFTR is a response of the ER quality control system to misfolded proteins, which prevents the progression of misfolded or misassembled membrane and secretory proteins into later compartments of the secretory pathway [3]. During synthesis, nascent CFTR polypeptide chains are translated from
Reduction of $m$-Regular Noncrossing Partitions
William Y. C. Chen,Eva Y. P. Deng,Rosena R. X. Du
Mathematics , 2004,
Abstract: In this paper, we present a reduction algorithm which transforms $m$-regular partitions of $[n]=\{1, 2, ..., n\}$ to $(m-1)$-regular partitions of $[n-1]$. We show that this algorithm preserves the noncrossing property. This yields a simple explanation of an identity due to Simion-Ullman and Klazar in connection with enumeration problems on noncrossing partitions and RNA secondary structures. For ordinary noncrossing partitions, the reduction algorithm leads to a representation of noncrossing partitions in terms of independent arcs and loops, as well as an identity of Simion and Ullman which expresses the Narayana numbers in terms of the Catalan numbers.
Riordan Paths and Derangements
William Y. C. Chen,Eva Y. P. Deng,Laura L. M. Yang
Mathematics , 2006,
Abstract: Riordan paths are Motzkin paths without horizontal steps on the x-axis. We establish a correspondence between Riordan paths and $(321,3\bar{1}42)$-avoiding derangements. We also present a combinatorial proof of a recurrence relation for the Riordan numbers in the spirit of the Foata-Zeilberger proof of a recurrence relation on the Schr\"oder numbers.
Crossings and Nestings of Matchings and Partitions
William Y. C. Chen,Eva Y. P. Deng,Rosena R. X. Du,Richard P. Stanley,Catherine H. Yan
Mathematics , 2005,
Abstract: We present results on the enumeration of crossings and nestings for matchings and set partitions. Using a bijection between partitions and vacillating tableaux, we show that if we fix the sets of minimal block elements and maximal block elements, the crossing number and the nesting number of partitions have a symmetric joint distribution. It follows that the crossing numbers and the nesting numbers are distributed symmetrically over all partitions of $[n]$, as well as over all matchings on $[2n]$. As a corollary, the number of $k$-noncrossing partitions is equal to the number of $k$-nonnesting partitions. The same is also true for matchings. An application is given to the enumeration of matchings with no $k$-crossing (or with no $k$-nesting).
Affine Deligne-Lusztig varieties and the action of J
Miaofen Chen,Eva Viehmann
Mathematics , 2015,
Abstract: We propose a new stratification of the reduced subschemes of Rapoport-Zink spaces and of affine Deligne-Lusztig varieties that highlights the relation between the geometry of these spaces and the action of the associated automorphism group. We show that this provides a joint group-theoretic interpretation of well-known stratifications which only exist for special cases such as the Bruhat-Tits stratification of Vollaard and Wedhorn, the semi-module stratification of de Jong and Oort, and the locus where the a-invariant is equal to 1.
Sodium Glucose Co-Transporter 2 (SGLT2) Inhibitors in Type 2 Diabetes: A Literature Review of Approved Products  [PDF]
Lucio R. Volino, Eva Y. Pan, Rupal Patel Mansukhani
Pharmacology & Pharmacy (PP) , 2014, DOI: 10.4236/pp.2014.511114
Abstract: Diabetes mellitus continues to be a major health issue worldwide. Despite all of the treatment options available on the market, many patients with diabetes fail to reach their treatment goals. Novel agents such as the Sodium-Glucose Cotransporter 2 (SGLT2) inhibitors show promise in effectively lowering blood glucose. Objective: To review the scientific literature for efficacy information regarding the use of approved SGLT2 inhibitors (canagliflozin, dapagliflozin and empagliflozin) in the treatment of Type 2 Diabetes Mellitus (T2DM). Methods: A MEDLINE (1950-August 2014) literature review was performed. All of the literature published as an original clinical trial was included in this review. Other pertinent articles published related to the original clinical trial were also included. Meta-analysis type studies were not selected for this review. Conclusions: With an increasing prevalence and incidence of type 2 diabetes mellitus worldwide, there is an apparent need for effective therapeutic strategies to combat this chronic and progressive disease. SGLT2 inhibitors offer this potential. Recently approved agents (canagliflozin, dapagliflozin and empagliflozin) have shown significant promise as mono- and add-on therapy to current glucose-lowering regimens that may not otherwise be providing sufficient glycemic control in T2DM patients.
An Alternative Approach to Particle-Particle Collisions  [PDF]
C. Y. Chen
Journal of Modern Physics (JMP) , 2015, DOI: 10.4236/jmp.2015.66082
Abstract: A new alternative approach to the statistical behavior of particle-particle collisions is introduced. The alternative approach is derived rigorously from well known mechanical laws; and the results given by it, quantitatively and qualitatively different from what the standard kinetic theory yields, can be directly checked with computer-simulated or realistic experiments. More importantly, from the introduction of it, a number of new concepts and new methodologies emerge, which might turn out to be very significant to the future development of nonequilibrium statistical mechanics.
The Lanczos-Chebyshev Pseudospectral Method for Solution of Differential Equations  [PDF]
Peter Y. P. Chen
Applied Mathematics (AM) , 2016, DOI: 10.4236/am.2016.79083
Abstract: In this paper, we propose to replace the Chebyshev series used in pseudospectral methods with the equivalent Chebyshev economized power series that can be evaluated more rapidly. We keep the rest of the implementation the same as the spectral method so that there is no new mathematical principle involved. We show by numerical examples that the new approach works well and there is indeed no significant loss of solution accuracy. The advantages of using power series also include simplicity in its formulation and implementation such that it could be used for complex systems. We investigate the important issue of collocation point selection. Our numerical results indicate that there is a clear accuracy advantage of using collocation points corresponding to roots of the Chebyshev polynomial.
Observation of Landau levels of Dirac fermions in graphite
Guohong Li,Eva Y. Andrei
Physics , 2007, DOI: 10.1038/nphys653
Abstract: The low energy electronic excitations in single layer and bilayer graphite (graphene) resemble quantum-relativistic particles also known as Dirac Fermions (DF). They possess an internal degree of freedom, chirality, that leads to unusual Landau Level (LL) energy sequences in a magnetic field and profoundly alters the magneto-transport properties. One of the consequences is an anomalous Quantum-Hall effect, recently detected in both single layer and bi-layer graphene. However the underlying cause, the unusual LL sequence, was never observed. Here we report the direct observation of LL of DF by means of low temperature Scanning-Tunnelling-Spectroscopy (STS) on the surface of graphite in fields up to 12 Tesla. We find evidence of coexistence of massless and massive DF, and identify the zero-energy LL which is a unique consequence of their quantum-relativistic nature. Surprisingly these strictly two-dimensional properties emerge even on bulk graphite in samples where the interlayer coupling is weak.
A Scalable Method for Cross-Platform Merging of SNP Array Datasets  [PDF]
Peikai Chen, Y. S. Hung
Engineering (ENG) , 2013, DOI: 10.4236/eng.2013.510B103
Abstract:

Single nucleotide polymorphism (SNP) array is a recently developed biotechnology that is extensively used in the study of cancer genomes. The various available platforms make cross-study validations/comparisons difficult. Meanwhile, sample sizes of the studies are fast increasing, which poses a heavy computational burden to even the fastest PC.Here, we describe a novel method that can generate a platform-independent dataset given SNP arrays from multiple platforms. It extracts the common probesets from individual platforms, and performs cross-platform normalizations and summari-zations based on these probesets. Since different platforms may have different numbers of probes per probeset (PPP), the above steps produce preprocessed signals with different noise levels for the platforms. To handle this problem, we adopt a platform-dependent smoothing strategy, and produce a preprocessed dataset that demonstrates uniform noise levels for individual samples.To increase the scalability of the method to a large number of samples, we devised an algorithm that split the samples into multiple tasks, and probesets into multiple segments before submitting to a parallel computing facility. This scheme results in a drastically reduced computation time and increased ability to process ultra-large sample sizes and arrays.

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