We present high resolution photoelectron energy spectra of noble gas atoms from high intensity above-threshold ionization (ATI) at midinfrared wavelengths. An unexpected structure at the very low-energy portion of the spectra, in striking contrast to the prediction of the simple-man theory, has been revealed. A semiclassical model calculation is able to reproduce the experimental feature and suggests the prominent role of the Coulomb interaction of the outgoing electron with the parent ion in producing the peculiar structure in long wavelength ATI spectra.

No abstract

We report on the fabrication of hollow microfluidic channels with a circular cross-sectional shape embedded in fused silica by spatiotemporally focusing the femtosecond laser beam. We demonstrate both theoretically and experimentally that the spatiotemporal focusing of femtosecond laser beam allows for the creation of a three-dimensionally symmetric spherical intensity distribution at the focal spot.

The diverse microbial communities that colonize distinct segments of the gastrointestinal tract are intimately related to aspects of physiology and the pathology of human health. However, most recent studies have focused on the rectal or fecal microbiota, and the microbial signature of the duodenum is poorly studied. In this study, we compared the microbiota in duodenal and rectal samples to illustrate the characteristic microbial signatures of the duodenum in healthy adults. Nine healthy volunteers donated biopsies and luminal contents from the duodenum and rectum. To determine the composition and diversity of the microbiota, 454- pyrosequencing of bacterial 16S rRNA was performed and multiple bioinformatics analyses were applied. The α-diversity and phylogenetic diversity of the microbiota in the duodenal samples were higher than those of the rectal samples. There was higher biodiversity among the microbiota isolated from rectal biopsies than feces. Proteobacteria were more highly represented in the duodenum than in the rectum, both in the biopsies and in the luminal contents from the healthy volunteers (38.7% versus 12.5%, 33.2% versus 5.0%, respectively). Acinetobacter and Prevotella were dominant in the duodenum, whereas Bacteroides and Prevotella were dominant in the rectum. Additionally, the percentage of OTUs shared in biopsy groups was far higher than in the luminal group (43.0% versus 26.8%) and a greater number of genera was shared among the biopsies than the luminal contents. Duodenal samples demonstrated greater biological diversity and possessed a unique microbial signature compared with the rectum. The mucosa-associated microbiota was more relatively conserved than luminal samples.

Abstract. The "Three Gorges Project" (TGP) in the upstream of Changjiang (Yangtze River) has resulted in great concern of scientific society and public conversations on the economic, environmental, and human health issues. Data of nutrients from main stream and 15 large tributaries indicate that Changjiang receives a large part of its nutrient burden from the drainage area upstream the "Three Gorges Dam" (TGD). A model calculation shows that the construction of TGD may cause further eutrophication in the upstream region with phosphate as a limiting factor relative to nitrogen for photosynthesis. The estimated carbon fixation within the reservoir may equal to 10-20% of the actual particulate organic carbon (POC) budget for the Changjiang. Taking into account the fact that dissolved inorganic nitrogen (DIN) in the Changjiang has increased by a factor of 2 in the last 10-20 years, the expected N:P ratio of the river would reach 300-400 after the year 2010. Such a change in nutrient and organic carbon budgets of the Changjiang will significantly influence the environment and health of ecosystems of the adjacent shelf region.

No abstract

No abstract

No abstract