The Role of Stereotype Threat in Mental Rotation

Numerous studies have been conducted on mental rotation ability in both males and females. A lot of the literature discusses male superiority in mental rotation task as opposed to females. This paper examined the role of stereotype threat in a mental rotation task. Particularly, the research study focused on gender stereotype threat in female college students. The study was completed in a two part design with students completing two mental rotation task in a group setting. The low numbers in the sample make it impossible to reliably say that the Vandenberg Mental Rotation Task (VMRT) and the Purdue Mental Rotation Task (Purdue) were measuring the exact same thing. There was a confound in part 2 of the study and we were unable to draw conclusions on the role of gender stereotype threat. However, the findings do suggest more support for the research on video game experience and mental rotation performance. The implications are discussed

Using Instructional Time and Race/Ethnicity to Predict Social Studies Accountability Test Results

This study investigated the relationship among the variables instructional time configuration, gender, race/ethnicity, and poverty to predict the academic performance of seventh-grade students on a state-mandated social studies accountability test. Results of 24,919 seventh-grade student social studies test scores from 117 middle schools, as well as a survey given to principals of the same 117 middle schools, were analyzed. A hierarchical multiple regression analysis showed that when controlling for poverty, the variables instructional time configuration and race/ethnicity were significant, explaining 11% of the variation in student social studies accountability test results; a small effect. Analysis of variance (ANOVA) and analysis of covariance (ANCOVA) were also used to illuminate the relationship of these variables on accountability test performance

The Interaction Of Multiple Convection Zones In A-type Stars

A-type stars have a complex internal structure with the possibility of multiple convection zones. If not sufficiently separated, such zones will interact through the convectively stable regions that lie between them. It is therefore of interest to ask whether the typical conditions that exist within such stars are such that these convections zones can ever be considered as disjoint. In this paper we present results from numerical simulations that help in understanding how increasing the distance between the convectively unstable regions are likely to interact through the stable region that separates them. This has profound implications for mixing and transport within these stars.Comment: 9 pages, 15 figures, Preprint accepted for publication in MNRA

Mercury concentration and speciation in coastal rainwater

Mercury exists in mainly two oxidation states in the atmosphere, Hg0 and Hg(II). Inorganic divalent mercury, Hg(II), has a greater solubility; therefore is in higher concentration in rainwater, than Hg0. The toxic species, methylmercury is an organic form of Hg(II) and is present in low concentration. Mercury is released into the atmosphere by natural and anthropogenic sources. Rainwater is thought to be a main removal mechanism for atmospheric mercury. The concentration and speciation of mercury were determined in rainwater from Wilmington, NC, from September 1, 2003 to September 30, 2005. Volume weighted averages for total Hg in unfiltered rainwater, total dissolved Hg, particulate Hg, dissolved gaseous Hg (Hg0) and methyl-Hg were 52.9 ± 4.7 pM, 40.6 ± 4.0 pM, 13.7± 1.5 pM, 4.3 ± 0.9 pM and 1.1 ± 0.1 pM, respectively. All mercury species were present in all seasons with no significant difference in concentrations between summer and winter, except dissolved gaseous mercury concentration was higher in the winter, with a higher ratio of Hg(II)/Hg(0) in summer relative to winter events. Diurnal variation was seen where Hg(II) decreased during the day into the night, suggesting photochemical reduction of Hg(II). All Hg concentrations were higher in continental storms relative to coastal rain events. Both total mercury species (UFHg and TDHg) were positively correlated with particulate mercury. Total mercury species were washed out of the atmosphere by rainwater with lower concentrations for larger rain events. A weak positive correlation was observed between TDHg and NO3 -, TDHg and SO4 2-, DGHg and Cl-, and Hgpart and DOC. The photochemistry of mercury from Wilmington was also investigated. UFHg, TDHg, and DGHg were generally produced upon irradiation of rainwater samples by simulated sunlight. Particulate Hg concentrations generally declined upon irradiation and MMHg concentrations showed no pattern, in some instances, increasing, decreasing or remaining the same. Positive correlation was observed between, production of UFHg and Hgpart and a negative correlation was observed between production of TDHg and Hgpart. Continental events increased in Hgpart while decreasing in TDHg, whereas coastal events increased in TDHg while decreasing in Hgpart after irradiation. Seasonal differences between Hg species were similar with an increase in TDHg and DGHg, while decreasing in Hgpart and greater changes were observed during the winter. Diurnal variations of Hg(II)/Hg(0) ratio increased during the afternoon and decreased there after. Atmospheric global inputs by natural and anthropogenic sources, 4.1 x 106 kg or 2.0 x 107 mol per year, were in good agreement with calculated total flux of mercury removed via wet deposition, 3.8 x 106 kg or 1.9 x 107 mol per year, suggesting that essentially all mercury released into the atmosphere is removed via rain

Perforated Meckel's diverticulitis complicating active Crohn's ileitis: a case report

<p>Abstract</p> <p>Introduction</p> <p>In Crohn's disease, the extension of active terminal ileitis into a Meckel's diverticulum is possible, but usually has no impact on clinical decision-making. We describe an original surgical approach in a young woman presenting with a combination of perforated Meckel's diverticulitis and active Crohn's ileitis.</p> <p>Case presentation</p> <p>We report the case of a 22-year-old woman with Crohn's disease, who was admitted for abdominal pain, fever and diarrhoea. CT scan demonstrated active inflammation of the terminal ileum, as well as a fluid collection in the right iliac fossa, suggesting intestinal perforation. Laparoscopy was performed and revealed, in addition to extensive ileitis, a 3 × 3 cm abscess in connection with perforated Meckel's diverticulitis. It was therefore possible to avoid ileocaecal resection by only performing Meckel's diverticulectomy; pathological examination of the surgical specimen revealed the presence of transmural inflammation with granulomas and perforation of the diverticulum at its extremity.</p> <p>Conclusion</p> <p>Crohn's disease of the ileum may be responsible for Meckel's diverticulitis and cause perforation which, in this case, proved to be a blessing in disguise and spared the patient an extensive small bowel resection.</p

Integrated motor drives: state of the art and future trends

With increased need for high power density, high efficiency and high temperature capabilities in Aerospace and Automotive applications, Integrated Motor Drives (IMD) offers a potential solution. However, close physical integration of the converter and the machine may also lead to an increase in components temperature. This requires careful mechanical, structural and thermal analysis; and design of the IMD system. This paper reviews existing IMD technologies and their thermal effects on the IMD system. The effects of the power electronics (PE) position on the IMD system and its respective thermal management concepts are also investigated. The challenges faced in designing and manufacturing of an IMD along with the mechanical and structural impacts of close physical integration is also discussed and potential solutions are provided. Potential converter topologies for an IMD like the Matrix converter, 2-level Bridge, 3-level NPC and Multiphase full bridge converters are also reviewed. Wide band gap devices like SiC and GaN and their packaging in power modules for IMDs are also discussed. Power modules components and packaging technologies are also presented