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Play Significant Roles (play + significant_role)
Selected AbstractsSURVIVE THEN THRIVE: DETERMINANTS OF SUCCESS IN THE ECONOMICS PH.D. PROGRAMECONOMIC INQUIRY, Issue 4 2007WAYNE A. GROVE This study investigates the completion of the Ph.D. in economics. We use ex ante information, based upon reviewing individual applications from former doctoral students. Students need different skills to succeed at each distinct stage of the doctoral program. Significant determinants for passing the comprehensive exams include Graduate Record Exam (GRE) verbal and quantitative scores, a Masters degree, and prior focus on economics. By contrast, research motivation and math preparation play significant roles in completing the dissertation. GRE scores become insignificant for completion in the generalized ordered logit estimates, which emphasize the sequential nature of the Economics Ph.D. program. (JEL I210) [source] Diversity of the cadherin-related neuronal receptor/protocadherin family and possible DNA rearrangement in the brainGENES TO CELLS, Issue 1 2003Takeshi Yagi Both the brain and the immune systems are complex. The complexity is generated by enormously diversified single cells. In the immune system, extensive cell death, gene regulation of immunoglobulin (Ig) and T-cell receptor (TCR) gene expression, and somatic rearrangement and mutations are known to generate an enormous diversity of lymphocytes. In this process, double-strand DNA breaks (DSBs) and DSB repair play significant roles. These processes at a DNA level are also physiologically significant in the nervous system during neurogenesis, and chromosomal variations have been detected in the nucleus of differentiated neurones. In another parallel with the immune system, cadherin-related neuronal receptors (CNRs) are diversified synaptic proteins. The CNR genes belong to protocadherin (Pcdh) gene clusters. Genomic organizations of CNR/Pcdh genes are similar to that of the Ig and TCR genes. Somatic mutations in and combinatorial gene regulation of CNR/Pcdh transcripts during neurogenesis have been reported. This review focuses on the diversity of the CNR/Pcdh genes and possible DNA diversification in the nervous system. [source] Maquiladora Employment Dynamics in Nuevo LaredoGROWTH AND CHANGE, Issue 1 2007JESÚS CAÑAS ABSTRACT The Nuevo Laredo maquiladora sector has grown enormously during the last two decades. The short-term time series characteristics of this portion of the regional economy are analyzed in an attempt to quantify the trends underlying this remarkable performance. Parameter estimation is accomplished via linear transfer function (LTF) analysis. Data are drawn from the January 1990,December 2000 sample period. Empirical results indicate that real wage rates, maquiladora plants, U.S. industrial activity, and the real exchange rate of the peso play significant roles in determining month-to-month fluctuations in maquiladora employment. Furthermore, sub-sample forecast simulation exercises are conducted as an additional means for verifying model reliability. Empirical results indicate that the forecasts generated with the LTF model are less accurate than those associated with a simple random walk procedure for twelve separate step-length periods. [source] A mixed logit model of health care provider choice: analysis of NSS data for rural IndiaHEALTH ECONOMICS, Issue 9 2006Bijan J. Borah Abstract In order to address the persistent problems of access to and delivery of health care in rural India, a better understanding of the individual provider choice decision is required. This paper is an attempt in this direction as it investigates the determinants of outpatient health care provider choice in rural India in the mixed multinomial logit (MMNL) framework. This is the first application of the mixed logit to the modeling of health care utilization. We also use the multiple imputation technique to impute the missing prices of providers that an individual did not visit when she was ill. Using data from National Sample Survey Organization of India, we find the following: price and distance to a health facility play significant roles in health care provider choice decision; when health status is poor, distance plays a less significant role in an adult's provider choice decision; price elasticity of demand for outpatient care varies with income, with low-income groups being more price-sensitive than high-income ones. Furthermore, outpatient care for children is more price-elastic than that for adults, which reflects the socio-economic structure of a typical household in rural India where an adult's health is more important than that of a child for the household's economic sustenance. Copyright © 2006 John Wiley & Sons, Ltd. [source] MT1-MMP, but not secreted MMPs, influences the migration of human microvascular endothelial cells in 3-dimensional collagen gelsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 4 2002Teruhiko Koike Abstract Matrix metalloproteinases (MMPs) and their specific inhibitors the TIMPs play significant roles in angiogenesis. We investigated how the expression of specific MMPs and TIMPs by human microvascular endothelial cells (hmECs) was modulated by culture of the cells in 3-dimensional (3D) type I collagen gels versus 2-dimensional (2D) collagen-coated surfaces. By reverse-transcription polymerase chain reaction (RT-PCR), levels of mRNA for MMPs-1, -2, and -13, MT1-MMP, and TIMPs-1 and -2 were similar in 2D versus 3D cultures. By Western blot assay, TIMP-1 and proMMP-1 were present and were expressed similarly in media from 2D versus 3D cultures, whereas active MMPs-1, -9, and -13 were not detected. Active MMP-13 was present in cell lysates (CL) and was increased in lysates from 3D cultures relative to 2D cultures. Relative to 2D cultures, CL and media from 3D cultures exhibited a decrease in expression of TIMP-2 and an increased conversion of proMMP-2 and proMT1-MMP to active or processed forms. The MMP inhibitor GM6001 interfered with the migration of hmECs in 3D cultures, but not in 2D cultures. Addition of active MMP-1 or blocking antibodies to TIMP-1 did not affect the migration of hmECs in 3D collagen. Migration in 3D collagen was decreased by TIMP-2 (an inhibitor of MT1-MMP), but not by TIMP-1 (a poor inhibitor of MT1-MMP, but an efficient inhibitor of MMP-2). Collectively, our data indicate that MT1-MMP contributes significantly to the movement of hmECs through 3D collagen, in contrast to secretory-type MMPs-1, -2, -9, and -13, which are not critical for this movement. J. Cell. Biochem. 86: 748,758, 2002. © 2002 Wiley-Liss, Inc. [source] Theoretical Studies of Damage to 3,-Uridine Monophosphate Induced by Electron AttachmentCHEMISTRY - A EUROPEAN JOURNAL, Issue 9 2008bo Zhang Ass. Abstract Low-energy electrons (LEE) are well known to induce nucleic acid damage. However, the damage mechanisms related to charge state and structural features remain to be explored in detail. In the present work, we have investigated the N1-glycosidic and C3,O(P) bond ruptures of 3,-UMP (UMP=uridine monophosphate) and the protonated form 3,-UMPH with ,1 and zero charge, respectively, based on hybrid density functional theory (DFT) B3,LYP together with the 6-31+G(d,p) basis set. The glycosidic bond breakage reactions of the 3,UMP and 3,UMPH electron adducts are exothermic in both cases, with barrier heights of 19,20,kcal,mol,1 upon inclusion of bulk solvation. The effects of the charge state on the phosphate group are marginal, but the C2,OH group destabilizes the transition structure of glycosidic bond rupture of 3,-UMPH in the gas phase by approximately 5.0,kcal,mol,1. This is in contrast with the C3,O(P) bond ruptures induced by LEE in which the charge state on the phosphate influences the barrier heights and reaction energies considerably. The barrier towards C3,O(P) bond dissociation in the 3,UMP electron adduct is higher in the gas phase than the one corresponding to glycosidic bond rupture and is dramatically influenced by the C2,OH group and bulk salvation, which decreases the barrier to 14.7,kcal,mol,1. For the C3,O(P) bond rupture of the 3,UMPH electron adduct, the reaction is exothermic and the barrier is even lower, 8.2,kcal,mol,1, which is in agreement with recent results for 3,-dTMPH and 5,-dTMPH (dTMPH=deoxythymidine monophosphate). Both the Mulliken atomic charges and unpaired-spin distribution play significant roles in the reactions. [source] Molecular mechanism of a cross-talk between oestrogen and growth factor signalling pathwaysGENES TO CELLS, Issue 8 2000Shigeaki Kato Oestrogen (E2) plays significant roles in variety of biological events such as the development and maintenance of female reproductive organs, bone and lipid metabolisms. More recently, from study of knock-out mice deficient in oestrogen receptor (ER) , and ER, it turned out that normal spermatogenesis requires the E2 actions. Furthermore, this female steroid hormone is also well known to be deeply involved in many pathophysiological events such as osteoporosis and cancer development in female reproductive organs. It is particularly well known that most breast cancer is dependent on E2 in its development. Such E2 actions are thought to be mediated through two subtypes of ERs. Growth factors have been shown to synergize in this E2 signalling pathway, although the actual molecular mechanism largely remains unknown. Recently, we found that the MAP kinase activated by growth factors phosphorylates the Ser118 residue of the human ER, A/B domain and this phosphorylation potentiates the N-terminal transactivation function (AF-1) of human ER,, indicating the possible molecular mechanism of a novel cross-talk between E2 and growth factor signalling pathways. More recently, we have identified a coactivator associating with the hER, AF-1 in a MAPK-mediated phosphorylation-dependent manner. In this review, the molecular mechanism of this cross-talk is discussed in terms of the transactivation function of ERs, and their coactivators. [source] | ||||||||||