Detailed and GlobalAnalysis of a Remedial Course's Impact on Incoming Students' Marks

Engineering incoming students are facing great difficulties to overcome first course subjects. To tackle that situation and increase the students’ success a Remedial course in Mathematics was offered to Informatics Engineering freshmen. This study presents a statistical analysis of their results comparing the marks obtained by those joining the course (studio group) versus those who did not participate (control group). ANOVA tests are performed over the students’ marks averages as well as over each subject students marks. These tests show statistically significant differences between both groups, with the studio group consistently outperforming the control group at 99% confidence level in most cases and at more than 92% confidence level in every case

Blade scale effects of tip leakage

October 1990Includes bibliographical references (leaves 43-44)The effects of blade-tip leakage in a turbine are investigated by modeling the stage as an incomplete actuator disk. It is found that the spanwise flow redistribution due to the gap is such as to produce a uniform unloading of the blades, despite the very concentrated leakage. Partial lift retention at the blade tip is accounted for based on a leakage jet-free stream collision model which successfully predicts the roll-up of the leakage flow. The predicted efficiency loss due to the gap correlates well with experimental data

Renormalization Group and Grand Unification with 331 Models

By making a renormalization group analysis we explore the possibility of having a 331 model as the only intermediate gauge group between the standard model and the scale of unification of the three coupling constants. We shall assume that there is no necessarily a group of grand unification at the scale of convergence of the couplings. With this scenario, different 331 models and their corresponding supersymmetric versions are considered, and we find the versions that allow the symmetry breaking described above. Besides, the allowed interval for the 331 symmetry breaking scale, and the behavior of the running coupling constants are obtained. It worths saying that some of the supersymmetric scenarios could be natural frameworks for split supersymmetry. Finally, we look for possible 331 models with a simple group at the grand unification scale, that could fit the symmetry breaking scheme described above.Comment: 18 pages. 3 figures. Some results reinterpreted, a new section and references added. Version to appear in International Journal of Modern Physics

Study of X52 steel in seawater with biocides under turbulent flow conditions

This work presents the corrosion study of the API X52 pipeline steel immersed in seawater without biocide and with 0,25, 0,5 and 0,75 ppm of biocide, under static and dynamic (turbulent flow) conditions at room temperature and atmospheric pressure. The total exposure time of the steel sample in test solution was 24h. In order to control the hydrodynamic conditions, a rotating cylinder electrode(RCE) was used. The rotation speed was 1000 RPM. The steel samples were immersed in the test solution, then, an electrochemical corrosion study using linear polarization resistance (LPR), electrochemical impedance spectroscopy (EIS) and polarization curves (PC) was made. In the superficial analysis of the steel samples, a scanning electronic microscopy was used. The results of the electrochemical study shown that the corrosion rate is higher under turbulent flow conditions than static conditions, and as the biocide concentration increased in the test solution, the corrosion rate decreased. A localized corrosion type was found in all the samples tested

Bank lending to small businesses in Latin America : does Bank origin matter?

In recent years foreign bank participation has increased tremendously in Latin America. Some observers argue that foreign bank entry will benefit Latin American banking systems by reducing the volatility of loans and deposits and increasing efficiency. Others are concerned that foreign banks might choose to extend credit only to certain customers, leaving some sectors-such as small businesses-unserved. The authors examine this issue. Using bank-level data for Argentina, Chile, Colombia, and Peru during the mid-1990s, they empirically investigate whether bank origin affects the share and growth rate of bank lending to small businesses. They find that although foreign banks generally lent less to small businesses (as share of total lending) than private domestic banks, the difference is due primarily to the behavior of small foreign banks. The difference was considerably smaller for large and medium-sized banks. And in Chile and Colombia, large foreign banks might actually lend slightly more (as share of total lending) than large domestic banks.Financial Intermediation,Banks&Banking Reform,Financial Crisis Management&Restructuring,Payment Systems&Infrastructure,Economic Theory&Research,Banks&Banking Reform,Financial Intermediation,Financial Crisis Management&Restructuring,Economic Theory&Research,Banking Law