Upper bounds on n-dimensional Kloosterman sums

Let pm be any prime power and Kn(a,pm) be the Kloosterman sum , where the xi are restricted to values not divisible by p. Let m,n be positive integers with m2 and suppose that pγ||(n+1). We obtain the upper bound |Kn(a,pm)|(n+1,p−1)p1/2min(γ,m−2)pmn/2, for odd p. For p=2 we obtain the same bound, with an extra factor of 2 inserted.postprin

Melanosomes or microbes: Testing an alternative hypothesis for the origin of microbodies in fossil feathers

Microbodies associated with fossil feathers, originally attributed to microbial biofilm, have been reinterpreted as melanosomes: pigment-containing, eukaryotic organelles. This interpretation generated hypotheses regarding coloration in non-avian and avian dinosaurs. Because melanosomes and microbes overlap in size, distribution and morphology, we re-evaluate both hypotheses. We compare melanosomes within feathers of extant chickens with patterns induced by microbial overgrowth on the same feathers, using scanning (SEM), field emission (FESEM) and transmission (TEM) electron microscopy. Melanosomes are always internal, embedded in a morphologically distinct keratinous matrix. Conversely, microbes grow across the surface of feathers in continuous layers, more consistent with published images from fossil feathers. We compare our results to both published literature and new data from a fossil feather ascribed to Gansus yumenensis (ANSP 23403). 'Mouldic impressions' were observed in association with both the feather and sediment grains, supporting a microbial origin. We propose criteria for distinguishing between these two microbodies

Model construction of telephone intervention transitional care among early discharged colostomy patients

2011-2012 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Debris Disks: Probing Planet Formation

Debris disks are the dust disks found around ~20% of nearby main sequence stars in far-IR surveys. They can be considered as descendants of protoplanetary disks or components of planetary systems, providing valuable information on circumstellar disk evolution and the outcome of planet formation. The debris disk population can be explained by the steady collisional erosion of planetesimal belts; population models constrain where (10-100au) and in what quantity (>1Mearth) planetesimals (>10km in size) typically form in protoplanetary disks. Gas is now seen long into the debris disk phase. Some of this is secondary implying planetesimals have a Solar System comet-like composition, but some systems may retain primordial gas. Ongoing planet formation processes are invoked for some debris disks, such as the continued growth of dwarf planets in an unstirred disk, or the growth of terrestrial planets through giant impacts. Planets imprint structure on debris disks in many ways; images of gaps, clumps, warps, eccentricities and other disk asymmetries, are readily explained by planets at >>5au. Hot dust in the region planets are commonly found (<5au) is seen for a growing number of stars. This dust usually originates in an outer belt (e.g., from exocomets), although an asteroid belt or recent collision is sometimes inferred.Comment: Invited review, accepted for publication in the 'Handbook of Exoplanets', eds. H.J. Deeg and J.A. Belmonte, Springer (2018

Tumor necrosis factor-α-induced protein 1 and immunity to hepatitis B virus

Aim: To compare the gene expression profile in a pair of HBV-infected twins. Methods: The gene expression profile was compared in a pair of H BV-infected twins. Results: The twins displayed different disease outco mes. One acquired natural immunity against HBV, whereas the other became a chronic HBV carrier. Eighty-eight and forty-six genes were found to be up- or downregulated in their PBMCs, respectively. Tumor necrosis factor-alpha-induced protein 1 (TNF-αIP1) that expressed at a higher level in the HBV-immune twins was identified and four pairs of siblings with HBV immunity by RT-PCR. However, upon HBV core antigen stimulation, TNF-αIP1 was downregulated in PBMCs from subjects with immunity, whereas it was slightly upregulated in HBV carriers. Bioinformatics analysis revealed a K+ channel tetramerization domain in TNF-αIP1 that shares a significant homology with some human, mouse, and C elegan proteins. Conclusion: TNF-αIP1 may play a role in the innate immunity against HBV. © 2005 The WJG Press and Elsevier Inc. All rights reserved.published_or_final_versio

Development of interfering RNA agents to inhibit SARS-associated coronavirus infection and replication.

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An Improved RSP Method to Detect HpaI Polymorphism in the Apolipoprotein C-1 Gene Promoter

BACKGROUND: An apolipoprotein C1 gene promoter polymorphism (CGTT insertion at position -317) is associated with familial dysbetalipoprotemia, cardiovascular diseases, and Alzheimer's disease. Restriction site polymorphism (RSP) assays were previously established to detect this polymorphism. In this study, we introduce an improved RSP assay to detect this polymorphism. METHODS: This method included newly designed primers and only one round of PCR amplification which yields one short and specific APOC1 fragment followed by HpaI digestion. Briefly, It consists of three steps: 1) one round of PCR amplification of DNA sample, 2) HpaI enzyme digestion of PCR products, and 3) electrophoresis on an agarose gel to visualize the genotypes. This improved RSP method was applied to genotype 92 human samples collected from The Johns Hopkins Hospital. RESULTS: The observed allele frequencies for H1 and H2 from 92 genotyped human subjects were 0.707 and 0.293 respectively. The H2 allele frequency in the black subjects (0.350) was significantly (p = 0.024) higher than that in the white subjects (0.177). This method was more economical and convenient than the methods previously reported to detect this mutation in the APOC1 gene. CONCLUSIONS: This assay will be readily applied to screen large sample sizes for population studies in a simple and cost effective way