Development of City Transport System and Two-wheel Vehicles

Based on the study on the city transport systems of some typical cities worldwide, this paper put forward that each city transport system has its own development mode, which is influenced by the city development plan, economic development level, traveling vehicle composition etc.. When some problems occur, such as the congestions caused by contradiction between the road capacity and vehicle composition, the city transport system may come into temporary maturity period. If the improvement for road system is limited meanwhile, optimized structure of vehicle composition should be an effective solution in this case. With the development of economy-internationalization, the development speed of city transport modernization is rapid. When traveling easiness is conflicting with efficiency, the advantages of public transport system become more obvious. Correspondingly, the superiority of two-wheel vehicles will reappear. Though the important function of two-wheel vehicles for alleviating city traffic problems i     

Rapid Manufacturing of Non-Assembly Complex Micro-Devices by Microstereolithography

This paper introduces a non-assembly manufacturing case with microstereolithography technology. The design and manufacturing process of a pneumatic thrust bearing is described, and a special tessellation method is developed to further improve the capability of the manufacturing system thus bigger products can also be easily manufactured. Implemented in a layer-by-layer fashion, stereolithography has been used for the rapid manufacturing of complex devices, and it avoids the expensive assembly process in the traditional manufacturing. This paper presents that microstereolithography can produce high-resolution products with intricate details, small openings, and smooth surfaces. The potential of the microstereolithograhy technique is explored for the rapid manufacturing of small and complex objects.     

A new species of Frasera (Gentianaceae) from Uinta Basin, Utah

Frasera ackermanae, sp. nov. is described based on specimens collected from the Brush Creek drainage, Uinta Basin in Uintah County, Utah. The short stem, compact inflorescence, and longer calyx lobes separate this species from the similar Frasera pahutensis Reveal.     

Deep sub-seafloor prokaryotes stimulated at interfaces over geological time

The sub-seafloor biosphere is the largest prokaryotic habitat on Earth but also a habitat with the lowest metabolic rates. Modelled activity rates are very low, indicating that most prokaryotes may be inactive or have extraordinarily slow metabolism. Here we present results from two Pacific Ocean sites, margin and open ocean, both of which have deep, subsurface stimulation of prokaryotic processes associated with geochemical and/or sedimentary interfaces. At 90 m depth in the margin site, stimulation was such that prokaryote numbers were higher (about 13-fold) and activity rates higher than or similar to near-surface values. Analysis of high-molecular-mass DNA confirmed the presence of viable prokaryotes and showed changes in biodiversity with depth that were coupled to geochemistry, including a marked community change at the 90-m interface. At the open ocean site, increases in numbers of prokaryotes at depth were more restricted but also corresponded to increased activity; however, this time they were associated with repeating layers of diatom-rich sediments (about 9 Myr old). These results show that deep sedimentary prokaryotes can have high activity, have changing diversity associated with interfaces and are active over geological timescales.     

Goblet cells deliver luminal antigen to CD103+ dendritic cells in the small intestine

The intestinal immune system is exposed to a mixture of foreign antigens from diet, commensal flora and potential pathogens. Understanding how pathogen-specific immunity is elicited while avoiding inappropriate responses to the background of innocuous antigens is essential for understanding and treating intestinal infections and inflammatory diseases. The ingestion of protein antigen can induce oral tolerance, which is mediated in part by a subset of intestinal dendritic cells (DCs) that promote the development of regulatory T cells. The lamina propria (LP) underlies the expansive single-cell absorptive villous epithelium and contains a large population of DCs (CD11c(+) CD11b(+) MHCII(+) cells) comprised of two predominant subsets: CD103(+) CX(3)CR1(-) DCs, which promote IgA production, imprint gut homing on lymphocytes and induce the development of regulatory T cells, and CD103(-) CX(3)CR1(+) DCs (with features of macrophages), which promote tumour necrosis factor-α (TNF-α) production, colitis, and the development of T(H)17 T cells. However, the mechanisms by which different intestinal LP-DC subsets capture luminal antigens in vivo remains largely unexplored. Using a minimally disruptive in vivo imaging approach we show that in the steady state, small intestine goblet cells (GCs) function as passages delivering low molecular weight soluble antigens from the intestinal lumen to underlying CD103(+) LP-DCs. The preferential delivery of antigens to DCs with tolerogenic properties implies a key role for this GC function in intestinal immune homeostasis.     

Positive and negative selection of an antigen receptor on T cells in transgenic mice

The T-cell repertoire found in the periphery is thought to be shaped by two developmental events in the thymus that involve the antigen receptors of T lymphocytes. First, interactions between T cells and major histocompatibility complex (MHC) molecules select a T-cell repertoire skewed towards recognition of antigens in the context of self-MHC molecules. In addition, T cells that react strongly to self-MHC molecules are eliminated by a process called self-tolerance. We have recently described transgenic mice expressing the alpha beta T-cell receptor from the cytotoxic T lymphocyte 2C (ref. 11). The clone 2C was derived from a BALB.B (H-2b) anti-BALB/c (H-2d) mixed lymphocyte culture and is specific for the Ld class I MHC antigen. In transgenic H-2b mice, a large fraction of T cells in the periphery expressed the 2C T-cell receptor. These T cells were predominantly CD4-CD8+ and were able to specifically lyse target cells bearing Ld. We now report that in the periphery of transgenic mice expressing Ld, functional T cells bearing the 2C T-cell receptor were deleted. This elimination of autoreactive T cells appears to take place at or before the CD4+CD8+ stage in thymocyte development. In addition, we report that in H-2s mice, a non-autoreactive target haplotype, large numbers of CD8+ T cells bearing the 2C T-cell receptor were not found, providing strong evidence for the positive selection of the 2C T-cell receptor specificity by H-2b molecules.     

Selective expression of an antigen receptor on CD8-bearing T lymphocytes in transgenic mice

The major problem in the study of T-cell development is that of tracking thymocytes of a given specificity. Recent studies have exploited natural correlations between the expression of a particular V beta gene segment and T-cell receptor (TCR) specificity. We and others (refs 5, 6 and M. Davis, personal communication) have taken an alternative approach. We have generated transgenic mice expressing the alpha beta antigen receptor from the cytotoxic T-lymphocyte clone 2C (ref. 7). In transgenic mice of the same haplotype as the 2C clone, the 2C TCR was expressed on 20-95% of peripheral T cells. Very few of these T cells carried the CD4 antigen; the vast majority were CD4-CD8+ and were able to lyse targets with the same specificity as the original 2C clone. These results indicate that the alpha beta heterodimer transfers specificity to recipient cells as expected from earlier studies, and that receptor specificity in T-cell repertoire selection is determined by both alpha beta heterodimer and CD4 or CD8 accessory molecules.