5,399 research outputs found
Banksâ capital, regulation and the financial crisis
This paper investigates whether regulatory capital requirements play an important role in determining banksâ equity capital. We estimate equity capital regressions using panel data of a sample of 560 banks for 2004-2010. Our results suggest that regulatory capital requirements are not first order determinants of banksâ capital structure. We document differences on the effect of most factors on banksâ share of equity according to the type of bank and to the region of the bank. Finally, we show that the determinants of this share are sensitive to the recent international financial crisis and to a set of regulatory country factors.info:eu-repo/semantics/publishedVersio
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Perceptual Learning in Mathematics: The Algebra-Geometry Connection
Important component of expertise is the rapid pickup complex. task-relevant pattern structure, yet such skills seldom trained explicitly. We report initial results ying principles of perceptual learning to the essing of structure in mathematics, specifically the ection between graphed functions and their symbolic essions. Subjects in two experiments viewed graphs inctions and made a speeded, forced choice match from ral equations. Training consisted of many short trials lis active classification task involving examples of a tion (e.g., sine) subjected to various transformations. scaling, shifting, reflection). Experiment 1 used rastive feedback â the graph for a trial was shown erimposed on the canonical function to accentuatejformations. Subjects showed substantial performance s from 45 minutes of training and transferred to new inces, new function families and a new task. In eriment 2, with contrastive feedback removed, subjects ved no transfer to new functions. The results indicate value of perceptual training in producing lematical expertise and the value of contrastive back in particular
Sustained gene expression in the retina by improved episomal vectors
Gene and cellular therapies are nowadays part of therapeutic strategies for the treatment of diverse pathologies. The drawbacks associated with gene therapy-low levels of transgene expression, vector loss during mitosis, and gene silencing-need to be addressed. The pEPI-1 and pEPito family of vectors was developed to overcome these limitations. It contains a scaffold/matrix attachment region, which anchors its replication to cell division in eukaryotic cells while in an extrachromosomal state and is less prone to silencing, due to a lower number of CpG motifs. Recent success showed that ocular gene therapy is an important tool for the treatment of several diseases, pending the overcome of the aforementioned limitations. To achieve sustained gene delivery in the retina, we evaluated several vectors based on pEPito and pEPI-1 for their ability to sustain transgene expression in retinal cells. These vectors stably transfected and replicated in retinal pigment epithelial (RPE) cells. Expression levels were promoter dependent with constitutive promoters cytomegalovirus immediate early promoter (CMV) and human CMV enhancer/human elongation factor 1 alpha promoter yielding the highest levels of transgene expression compared with the retina-specific RPE65 promoter. When injected in C57Bl6 mice, transgene expression was sustained for at least 32 days. Furthermore, the retina-specific RPE65 promoter showed higher efficiency in vivo compared to in vitro. In this study, we demonstrate that by combining tissue-specific promoters with a mitotic stable system, less susceptible to epigenetic silencing such as pEPito-based plasmids, we can achieve prolonged gene expression and a sustained therapeutic effect.Fundacao para a Ciencia e Tecnologia, Portugal [PEst/OE/EQB-LA 0023/2013, SFRH/BD/76873/2011, SFRH/BD/70318/2010, PTDC/SAU/BEB/098475/2008]; European Union [PIRG-GA-2009-249314
Noise Reduction and Control in Hospital Environment: Design of the NeoNoise Project
The âNeoNoise Project: Integrated Approach to Minimize Sound Pressure Levels in Neonatal Intensive Care Unitsâ is being conducted by the Research Group on Occupational and Environmental Health of the Research Center on Health and Environment in neonatal intensive care units, since exposure to sound pressure levels in these spaces has been recognized as a factor that influences the quality and wellâbeing of the occupants (workers and others), as well as the recovery of premature infants who are hospitalized. This work reports the rationale and the design of the NeoNoise project as well as the methods used for data collection. A brief review on the results published and available for the scientific community is also made. In general, NeoNoise project intends to make an integration of all relevant factors, with the intention of presenting a guiding document to change the working practices and occupant\u27s behaviors. So far, this study provided data on sound pressure levels by objective and subjective approaches, as well as information about the exposure factors and sensitivity of the occupants to noise
Fasting Glucose Metabolism in Pregnancy
The HAPO study found a continuous association between hyperglycemia at 24-32 weeks of gestation, below the diagnostic levels of gestational diabetes mellitus (GDM), and adverse pregnancy outcomes, suggesting the need to reconsider the diagnostic criteria for GDM. Recently, a consensus for diagnosis of diabetes in pregnancy was published, based on the results of the HAPO study. Diagnosing for diabetes is considered already in the first trimester with fasting plasma glucose (FPG), but oral glucose tolerance test is recommended to be performed only at 24-28 weeks of gestation. Identifying all pregnant women at risk for GDM in the first trimester would allow an individualization of obstetric care and establishment of a dietetic and exercise plan since earlier stages of pregnancy with potential benefits for both mother and fetus.
The glycemic metabolism varies throughout pregnancy, as insulin resistance increases during pregnancy. However the cut-off values for blood glucose tests in screening and diagnosing GDM are independent of gestational age.
The objectives of this study are to verify if the pregnant women with and without GDM diagnosed in the second/third trimester are already different from each other in the first trimester regarding FPG levels and to study the evolution of the FPG throughout pregnancy
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The Microenvironment Determines the Breast Cancer Cells' Phenotype: Organization of MCF7 Cells in 3D Cultures
Background: Stromal-epithelial interactions mediate breast development, and the initiation and progression of breast cancer. In the present study, we developed 3-dimensional (3D) in vitro models to study breast cancer tissue organization and the role of the microenvironment in phenotypic determination. Methods: The human breast cancer MCF7 cells were grown alone or co-cultured with primary human breast fibroblasts. Cells were embedded in matrices containing either type I collagen or a combination of reconstituted basement membrane proteins and type I collagen. The cultures were carried out for up to 6 weeks. For every time point (1-6 weeks), the gels were fixed and processed for histology, and whole-mounted for confocal microscopy evaluation. The epithelial structures were characterized utilizing immunohistochemical techniques; their area and proliferation index were measured using computerized morphometric analysis. Statistical differences between groups were analyzed by ANOVA, Dunnett's T3 post-hoc test and chi-square. Results: Most of the MCF7 cells grown alone within a collagen matrix died during the first two weeks; those that survived organized into large, round and solid clusters. The presence of fibroblasts in collagen gels reduced MCF7 cell death, induced cell polarity, and the formation of round and elongated epithelial structures containing a lumen. The addition of reconstituted basement membrane to collagen gels by itself had also survival and organizational effects on the MCF7 cells. Regardless of the presence of fibroblasts, the MCF7 cells both polarized and formed a lumen. The addition of fibroblasts to the gel containing reconstituted basement membrane and collagen induced the formation of elongated structures. Conclusions: Our results indicate that a matrix containing both type I collagen and reconstituted basement membrane, and the presence of normal breast fibroblasts constitute the minimal permissive microenvironment to induce near-complete tumor phenotype reversion. These human breast 3D tissue morphogenesis models promise to become reliable tools for studying tissue interactions, therapeutic screening and drug target validation
Exploring the Effects of bolA in Biofilm Formation and Current Generation by Shewanella oneidensis MR-1
Microbial electrochemical technologies (METs) have emerged in recent years as a promising alternative green source of energy, with microbes consuming organic matter to produce energy or valuable byproducts. It is the ability of performing extracellular electron transfer that allows these microbes to exchange electrons with an electrode in these systems. The low levels of current achieved have been the limiting factor for the large-scale application of METs. Shewanella oneidensis MR-1 is one of the most studied electroactive organisms regarding extracellular electron transfer, and it has been shown that biofilm formation is a key factor for current generation. The transcription factor bolA has been identified as a central player in biofilm formation in other organisms, with ist overexpression leading to increased biofilm. In this work we explore the effect of this gene in biofilm formation and current production by S. oneidensis MR-1. Our results demonstrate that an increased biofilm formation and consequent current generation was achieved by the overexpression of this gene. This information is crucial to optimize electroactive organisms toward their practical application in METs
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