1,621 research outputs found

    Large earthquakes create vertical permeability by breaching aquitards

    Get PDF
    Hydrologic responses to earthquakes and their mechanisms have been widely studied. Some responses have been attributed to increases in the vertical permeability. However, basic questions remain: How do increases in the vertical permeability occur? How frequently do they occur? Is there a quantitative measure for detecting the occurrence of aquitard breaching? We try to answer these questions by examining data from a dense network of ∼50 monitoring stations of clustered wells in a sedimentary basin near the epicenter of the 1999 M7.6 Chi-Chi earthquake in western Taiwan. While most stations show evidence that confined aquifers remained confined after the earthquake, about 10% of the stations show evidence of coseismic breaching of aquitards, creating vertical permeability as high as that of aquifers. The water levels in wells without evidence of coseismic breaching of aquitards show tidal responses similar to that of a confined aquifer before and after the earthquake. Those wells with evidence of coseismic breaching of aquitards, on the other hand, show distinctly different postseismic tidal response. Furthermore, the postseismic tidal response of different aquifers became strikingly similar, suggesting that the aquifers became hydraulically connected and the connection was maintained many months thereafter. Breaching of aquitards by large earthquakes has significant implications for a number of societal issues such as the safety of water resources, the security of underground waste repositories, and the production of oil and gas. The method demonstrated here may be used for detecting the occurrence of aquitard breaching by large earthquakes in other seismically active areas

    Improved Cell Survival and Paracrine Capacity of Human Embryonic Stem Cell-Derived Mesenchymal Stem Cells Promote Therapeutic Potential for Pulmonary Arterial Hypertension.

    Get PDF
    Although transplantation of adult bone marrow mesenchymal stem cells (BM-MSCs) holds promise in the treatment for pulmonary arterial hypertension (PAH), the poor survival and differentiation potential of adult BM-MSCs have limited their therapeutic efficiency. Here, we compared the therapeutic efficacy of human embryonic stem cell-derived MSCs (hESC-MSCs) with adult BM-MSCs for the treatment of PAH in an animal model. One week following monocrotaline (MCT)-induced PAH, mice were randomly assigned to receive phosphate-buffered saline (MCT group); 3.0×106 human BM-derived MSCs (BM-MSCs group) or 3.0 ×106 hESC-derived MSCs (hESC-MSCs group) via tail vein injection. At 3 weeks posttransplantation, the right ventricular systolic pressure (RVSP), degree of RV hypertrophy, and medial wall thickening of pulmonary arteries were lower=, and pulmonary capillary density was higher in the hESC-MSC group as compared with BM-MSC and MCT groups (all p < 0.05). At 1 week posttransplantation, the number of engrafted MSCs in the lungs was found significantly higher in the hESC-MSC group than in the BM-MSC group (all p < 0.01). At 3 weeks posttransplantation, implanted BM-MSCs were undetectable whereas hESC-MSCs were not only engrafted in injured pulmonary arteries but had also undergone endothelial differentiation. In addition, protein profiling of hESC-MSC- and BM-MSC-conditioned medium revealed a differential paracrine capacity. Classification of these factors into bioprocesses revealed that secreted factors from hESC-MSCs were preferentially involved in early embryonic development and tissue differentiation, especially blood vessel morphogenesis. We concluded that improved cell survival and paracrine capacity of hESC-MSCs provide better therapeutic efficacy than BM-MSCs in the treatment for PAH. © 2012 Cognizant Comm. Corp.published_or_final_versio

    Human papillomavirus status in southern Chinese women

    Get PDF
    1. The overall and type-specific human papillomavirus (HPV) prevalence differed between Hong Kong and Guangzhou healthy women. The prevalence of HPV was significantly higher in Guangzhou than Hong Kong women. Younger women had significantly higher risk of HPV infection. 2. HPV16 remained the most common type detected in both regions; the frequency increased with increasing disease severity. The prevalence of HPV58 and HPV52 was relatively high in women with normal cervix and precancerous lesions.published_or_final_versio

    The role of tool geometry in process damped milling

    Get PDF
    The complex interaction between machining structural systems and the cutting process results in machining instability, so called chatter. In some milling scenarios, process damping is a useful phenomenon that can be exploited to mitigate chatter and hence improve productivity. In the present study, experiments are performed to evaluate the performance of process damped milling considering different tool geometries (edge radius, rake and relief angles and variable helix/pitch). The results clearly indicate that variable helix/pitch angles most significantly increase process damping performance. Additionally, increased cutting edge radius moderately improves process damping performance, while rake and relief angles have a smaller and closely coupled effect

    Improved Cell Survival and Paracrine Capacity of Human Embryonic Stem Cell-Derived Mesenchymal Stem Cells Promote Therapeutic Potential for Pulmonary Arterial Hypertension.

    Get PDF
    Although transplantation of adult bone marrow mesenchymal stem cells (BM-MSCs) holds promise in the treatment for pulmonary arterial hypertension (PAH), the poor survival and differentiation potential of adult BM-MSCs have limited their therapeutic efficiency. Here, we compared the therapeutic efficacy of human embryonic stem cell-derived MSCs (hESC-MSCs) with adult BM-MSCs for the treatment of PAH in an animal model. One week following monocrotaline (MCT)-induced PAH, mice were randomly assigned to receive phosphate-buffered saline (MCT group); 3.0×106 human BM-derived MSCs (BM-MSCs group) or 3.0 ×106 hESC-derived MSCs (hESC-MSCs group) via tail vein injection. At 3 weeks posttransplantation, the right ventricular systolic pressure (RVSP), degree of RV hypertrophy, and medial wall thickening of pulmonary arteries were lower=, and pulmonary capillary density was higher in the hESC-MSC group as compared with BM-MSC and MCT groups (all p < 0.05). At 1 week posttransplantation, the number of engrafted MSCs in the lungs was found significantly higher in the hESC-MSC group than in the BM-MSC group (all p < 0.01). At 3 weeks posttransplantation, implanted BM-MSCs were undetectable whereas hESC-MSCs were not only engrafted in injured pulmonary arteries but had also undergone endothelial differentiation. In addition, protein profiling of hESC-MSC- and BM-MSC-conditioned medium revealed a differential paracrine capacity. Classification of these factors into bioprocesses revealed that secreted factors from hESC-MSCs were preferentially involved in early embryonic development and tissue differentiation, especially blood vessel morphogenesis. We concluded that improved cell survival and paracrine capacity of hESC-MSCs provide better therapeutic efficacy than BM-MSCs in the treatment for PAH. © 2012 Cognizant Comm. Corp.published_or_final_versio

    Biodegradable Thermosensitive Hydrogel for SAHA and DDP Delivery: Therapeutic Effects on Oral Squamous Cell Carcinoma Xenografts

    Get PDF
    Background: OSCC is one of the most common malignancies and numerous clinical agents currently applied in combinative chemotherapy. Here we reported a novel therapeutic strategy, SAHA and DDP-loaded PECE (SAHA-DDP/PECE), can improve the therapeutic effects of intratumorally chemotherapy on OSCC cell xenografts. Objective/Purpose: The objective of this study was to evaluate the therapeutic efficacy of the SAHA-DDP/PECE in situ controlled drug delivery system on OSCC cell xenografts. Methods: A biodegradable and thermosensitive hydrogel was successfully developed to load SAHA and DDP. Tumorbeared mice were intratumorally administered with SAHA-DDP/PECE at 50 mg/kg (SAHA) +2 mg/kg (DDP) in 100 ul PECE hydrogel every two weeks, SAHA-DDP at 50 mg/kg(SAHA) +2 mg/kg(DDP) in NS, 2 mg/kg DDP solution, 50 mg/kg SAHA solution, equal volume of PECE hydrogel, or equal volume of NS on the same schedule, respectively. The antineoplastic actions of SAHA and DDP alone and in combination were evaluated using the determination of tumor volume, immunohistochemistry, western blot, and TUNEL analysis. Results: The hydrogel system was a free-flowing sol at 10uC, become gel at body temperature, and could sustain more than 14 days in situ. SAHA-DDP/PECE was subsequently injected into tumor OSCC tumor-beared mice. The results demonstrated that such a strategy as this allows the carrier system to show a sustained release of SAHA and DDP in vivo, and coul

    Conscious monitoring and control (reinvestment) in surgical performance under pressure.

    Get PDF
    Research on intraoperative stressors has focused on external factors without considering individual differences in the ability to cope with stress. One individual difference that is implicated in adverse effects of stress on performance is "reinvestment," the propensity for conscious monitoring and control of movements. The aim of this study was to examine the impact of reinvestment on laparoscopic performance under time pressure

    Inter-Allelic Prion Propagation Reveals Conformational Relationships among a Multitude of [PSI] Strains

    Get PDF
    Immense diversity of prion strains is observed, but its underlying mechanism is less clear. Three [PSI] prion strains—named VH, VK, and VL—were previously isolated in the wild-type yeast genetic background. Here we report the generation and characterization of eight new [PSI] isolates, obtained by propagating the wild-type strains with Sup35 proteins containing single amino-acid alterations. The VH strain splits into two distinct strains when propagated in each of the three genetic backgrounds, harboring respectively single mutations of N21L, R28P, and Gi47 (i.e. insertion of a glycine residue at position 47) on the Sup35 N-terminal prion-forming segment. The six new strains exhibit complex inter-conversion patterns, and one of them continuously mutates into another. However, when they are introduced back into the wild-type background, all 6 strains revert to the VH strain. We obtain two more [PSI] isolates by propagating VK and VL with the Gi47 and N21L backgrounds, respectively. The two isolates do not transmit to other mutant backgrounds but revert to their parental strains in the wild-type background. Our data indicate that a large number of [PSI] strains can be built on three basic Sup35 amyloid structures. It is proposed that the three basic structures differ by chain folding topologies, and sub-strains with the same topology differ in distinct ways by local structural adjustments. This “large number of variations on a small number of basic themes” may also be operative in generating strain diversities in other prion elements. It thus suggests a possible general scheme to classify a multitude of prion strains
    corecore