698 research outputs found
Representations of boundary layer cloudiness and surface wind probability distributions in subtropical marine stratus and stratocumulus regions
Representations of Boundary Layer Cloudiness and Surface Wind Probability Distributions in Subtropical Marine Stratus and Stratocumulus Regions
Yanping He
153 pages
Directed by Dr. Robert E. Dickinson
A simple low cloud cover scheme is developed for the subtropical marine stratus and stratocumulus (MSC) regions. It is based on a modified CIN concept named the Lower Troposphere Available Dry Inhibition Energy (ADIN). The e-folder time for the local change of ADIN is found to be approximately 6 to 7 hours. On monthly and longer timescales, local productions of ADIN are balanced by local destructions of ADIN within lower troposphere. Dynamical transport of environmental dry static energy and surface evaporation lead to the variations of cloud top radiative cooling, which is a linear function of low cloud cover. Data analysis suggests that total ADIN dynamical transport plays the most important role in determining the seasonal variations and spatial variations of low cloud amounts¡£
The new scheme produces realistic seasonal and spatial variations of both EECRA ship observation and satellite observations in all MSC regions. It explains 25% more covariance than that using Klein-Hartmann (KH) scheme for monthly ISCCP low cloud amount near the Peruvian and Canarian region during the period from 1985 to 1997£¬it better represents the relationship between ENSO index and low cloud cover variations near the Peruvian region. When implemented into NCAR CAM3.1, it systematically reduces the model biases in the summertime spatial variations of low cloud amount and downward solar radiation in the Peruvian, California, and Canarian regions. Model simulated summertime cloud liquid water path, large scale precipitation, and surface fluxes are also significantly changed.
A single predictor named Lower troposphere available thermal inhibition energy (ATIN) is also shown to be more skillful than the lower tropospheric stability in diagnosing low cloud stratiform clouds in the monthly and seasonal timescales. On synoptic timescale, dynamical transport of available dry inhibition energy and surface evaporation are better correlated with marine low cloud amount variations than ATIN and lower troposphere stability.
The influence of boundary layer clouds, ocean surface SST, and large scale divergence on the stochastic dynamics of local ocean surface winds are addressed using QuikSCAT and AIRS satellite observations and a simple conceptual model in the southeast Pacific. The ocean surface pressure gradient depends on both the boundary layer height and temperature inversion strength. Marine boundary clouds are diagnosed using the cloud cover scheme developed in Chapter 2. The model successfully reproduces the observed mean state, the standard deviation, and skewness of local surface wind speeds in the southeast Pacific.Ph.D.Committee Chair: Dr. Robert E. Dickinson; Committee Member: Dr. Irina Sokolik; Committee Member: Dr. Judth Curry; Committee Member: Dr. Peter Webster; Committee Member: Dr. Rong F
A Domain Decomposition Method for the Steady-State Navier-Stokes-Darcy Model with Beavers-Joseph Interface Condition
This paper proposes and analyzes a Robin-type multiphysics domain decomposition method (DDM) for the steady-state Navier-Stokes-Darcy model with three interface conditions. In addition to the two regular interface conditions for the mass conservation and the force balance, the Beavers-Joseph condition is used as the interface condition in the tangential direction. The major mathematical difficulty in adopting the Beavers-Joseph condition is that it creates an indefinite leading order contribution to the total energy budget of the system [Y. Cao et al., Comm. Math. Sci., 8 (2010), pp. 1-25; Y. Cao et al., SIAM J. Numer. Anal., 47 (2010), pp. 4239-4256]. In this paper, the well-posedness of the Navier-Stokes-Darcy model with Beavers-Joseph condition is analyzed by using a branch of nonsingular solutions. By following the idea in [Y. Cao et al., Numer. Math., 117 (2011), pp. 601-629], the three physical interface conditions are utilized together to construct the Robin-type boundary conditions on the interface and decouple the two physics which are described by Navier-Stokes and Darcy equations, respectively. Then the corresponding multiphysics DDM is proposed and analyzed. Three numerical experiments using finite elements are presented to illustrate the features of the proposed method and verify the results of the theoretical analysis
Preparation and properties of compound Arnebiae radix microemulsion gel
Background: Compound Arnebiae radix oil has been clinically applied to treat burns and scalds for a long time. However, it is unstable and inconvenient to use. The aim of this study was to prepare a compound Arnebiae radix microemulsion gel for transdermal delivery system and evaluate its characteristics.Materials and Methods: Based on the solubility of Shikonin, the active component of Arnebiae radix and the results of phase studies, adequate ratio of each component in microemulsion was determined. The optimized microemulsion gel was prepared using Carbomer 940. The gels were characterized in terms of appearance, preliminary stability test and the content of Shikonin in the compound Arnebiae radix microemulsion gel with HPLC analysis.Results: The optimized conditions for preparing microemulsion were Tween-80, glycerin, isopropyl myristate (IPM) with the ratio of 6:3:2. The optimal microemulsion gel was obtained with Carbomer 940 (1.0%).Conclusion: The prepared compound Arnebiae radix microemulsion gel showed good stability over time. It is more convenience in application than the previous used formulations.Keywords: Compound Arnebiae radix oil, microemulsion gel, pseudo-ternary phase diagram, characterizatio
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Joint Association of Dietary Pattern and Physical Activity Level with Cardiovascular Disease Risk Factors among Chinese Men: A Cross-Sectional Study
The purpose of this cross-sectional study was to investigate the joint associations of physical activity level (PAL) and dietary patterns in relation to cardiovascular disease (CVD) risk factors among Chinese men. The study population consisted of 13 511 Chinese males aged 18–59 years from the 2002 China National Nutrition and Health Survey. Based on dietary data collected by a food frequency questionnaire, four dietary patterns were identified and labeled as “Green Water” (high consumption of rice, vegetables, seafood, pork, and poultry), “Yellow Earth” (high consumption of wheat flour products and starchy tubers), “New Affluent” (high consumption of animal sourced foods and soybean products), and “Western Adopter” (high consumption of animal sourced foods, cakes, and soft drinks). From the information collected by a 1-year physical activity questionnaire, PAL was calculated and classified into 4 categories: sedentary, low active, active, and very active. As compared with their counterparts from the New Affluent pattern, participants who followed the Green Water pattern had a lower likelihood of abdominal obesity (AO; 50.2%), hypertension (HT; 37.9%), hyperglycemia (HG; 41.5%), elevated triglyceride (ETG; 14.5%), low HDL (LHDL; 39.8%), and metabolic syndrome (MS; 51.9%). When compared to sedentary participants, the odds ratio of participants with very active PAL was 0.62 for AO, 0.85 for HT, 0.71 for HG, 0.76 for ETG, 0.74 for LHDL, and 0.58 for MS. Individuals who followed both very active PAL and the Green Water pattern had a lower likelihood of CVD risk factors (AO: 65.8%, HT: 39.1%, HG: 57.4%, ETG: 35.4%, LHDL: 56.1%, and MS: 75.0%), compared to their counterparts who followed both sedentary PAL and the New Affluent pattern. In addition, adherence to both healthy dietary pattern and very active PAL presented a remarkable potential for CVD risk factor prevention
Comparative transcriptomics in Yersinia pestis: a global view of environmental modulation of gene expression
<p>Abstract</p> <p>Background</p> <p>Environmental modulation of gene expression in <it>Yersinia pestis </it>is critical for its life style and pathogenesis. Using cDNA microarray technology, we have analyzed the global gene expression of this deadly pathogen when grown under different stress conditions <it>in vitro</it>.</p> <p>Results</p> <p>To provide us with a comprehensive view of environmental modulation of global gene expression in <it>Y. pestis</it>, we have analyzed the gene expression profiles of 25 different stress conditions. Almost all known virulence genes of <it>Y. pestis </it>were differentially regulated under multiple environmental perturbations. Clustering enabled us to functionally classify co-expressed genes, including some uncharacterized genes. Collections of operons were predicted from the microarray data, and some of these were confirmed by reverse-transcription polymerase chain reaction (RT-PCR). Several regulatory DNA motifs, probably recognized by the regulatory protein Fur, PurR, or Fnr, were predicted from the clustered genes, and a Fur binding site in the corresponding promoter regions was verified by electrophoretic mobility shift assay (EMSA).</p> <p>Conclusion</p> <p>The comparative transcriptomics analysis we present here not only benefits our understanding of the molecular determinants of pathogenesis and cellular regulatory circuits in <it>Y. pestis</it>, it also serves as a basis for integrating increasing volumes of microarray data using existing methods.</p
Over-expression of human cytomegalovirus miR-US25-2-3p downregulates eIF4A1 and inhibits HCMV replication
AbstractIt has been reported that human cytomegalovirus (HCMV) miR-US25-2 reduces DNA viral replication including HCMV. However, the mechanism remains unknown. In our study, eukaryotic translation initiation factor 4A1 (eIF4A1) was identified to be a direct target of miR-US25-2-3p. Small interfering RNA (siRNA) and miR-US25-2-3p mediated eIF4A1 knockdown experiments revealed that high level of miR-US25-2-3p in MRC-5 cells decreased HCMV and host genomic DNA synthesis, and inhibited cap-dependent translation and host cell proliferation. However, eIF4A1 up-regulation induced by miR-US25-2-3p inhibitor increased HCMV copy number. Therefore, the over-expression of miR-US25-2-3p and consequent lower expression of eIF4A1 may contribute to the inhibition of HCMV replication
Preparation of desulfurizing activated carbon from corn stalk and characterization of desulfurizing structure
This study investigated the optimal conditions for preparing desulfurizing stalk carbon, using corn stalk as a raw material and zinc chloride as an activator. The structure of stalk carbon was characterized using thermogravimetry (TG), fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Brunauer – Emmelt – Teller (BET). Results found no significant difference in stalk carbon desulfurization properties when using stalk skin, core, or a skin-core mixture as raw material. The desulfurization performance of stalk carbon prepared using a skin-core mixture, was the most effective when the material : liquid ratio was 1:2; activation temperature was 350 °C; and activation time was 70 min. The corresponding H2S adsorption time was 74 min. The large specific surface area of 562.28 m2/g and abundant pore-volume of 0.3851 ml/g was found in the desulfurization stalk carbon prepared using these conditions. The increase in micropores and the abundant oxygen-containing functional surface groups were conducive to H2S adsorption. The desulfurization products were found to be mainly elemental S and sulfite
Kaposi`s sarcoma associated herpesvirus infection among female sex workers and general population women in Shanghai, China: a cross-sectional study
Background: Limited information on epidemiologic patterns of KSHV, with none focusing on heterosexual transmission, is available in mainland China. To clarify this, a cross-sectional study was conducted among a group of female sex workers (FSW) and general population women (GW) in Shanghai, China.
Methods: An anonymous questionnaire interview was administrated among 600 FSW and 600 GW. Blood samples were collected and tested for antibodies to KSHV, HSV-2, HIV, syphilis and HBsAg. Correlates of KSHV and HSV-2 were examined using multiple logistic regression analysis.
Results: None of the study participants were tested positive for HIV. The seroprevalence of KSHV, HSV-2 , HBV and syphilis was 10.0%, 52.2%, 12.3% and 10.5%, respectively for FSW, and was 11.0%, 15.3%, 9.8% and 2.8%, respectively for GW. KSHV seropositivity was not associated with syphilis and HSV-2 infection as well as sexual practices among either FSW or GW. Nevertheless, HSV-2 infection among FSW was independently associated with being ever married (OR = 1.59; 95%CI: 1.04-2.45), \u3e5 years of prostitution (OR = 2.06; 95%CI: 1.16-3.68) and being syphilis positive (OR = 2.65; 95%CI: 1.43-4.93). HSV-2 infection among GW was independently associated with an age of \u3e35 years (OR = 2.29; 95%CI: 1.07-4.93), having had more than 2 sex partners in the prior 12 months (OR = 6.44; 95%CI: 1.67-24.93) and being syphilis positive (OR = 3.94; 95%CI: 1.38-11.23). A gradual increase of prevalence with the prostitution time group was also detected for HSV-2 and syphilis, but not for KSHV.
Conclusions: KSHV is moderately and equivalently prevalent among FSW and GW. Heterosexual contact is not a predominant route for KSHV transmission among Chinese women
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