Traveling-wave tube circuit simplifies microwave relay

Circuit with a sawtooth-modulated traveling-wave tube, which acts as a frequency converter and as an amplifier, simplifies microwave transmission. Lower power losses and reduced size and weight are also realized in this circuit

Equilibrium sequences of hybrid stars with LOFF matter core

We study equilibrium configurations of hybrid stars with inhomogeneous Color SuperConducting (CSC) phases in the inner core and a mantle of nuclear matter

Biologically active molecules from marine microalgae

Diatoms are unicellular photosynthetic microalgae responsible for approximately 40% of marine primary productivity. This algal class has traditionally been regarded as providing the bulk of the food that sustains the marine food chain to top consumers and important fisheries. However, this beneficial role has recently been questioned on the basis of laboratory and field studies showing that although dominant zooplankton grazers such as copepods feed extensively on diatoms, the hatching success of eggs thus produced is seriously impaired. Short chain polyunsaturated aldehydes, such as 2,4,7-decatrienal and 2,4-decadienal, were correlated to the antiproliferative effect of diatoms on copepod reproduction. After establishing a method of analysis, the aldehyde profile of some ecologically relevant species of marine diatoms was assessed. The results showed that the production of aldehydes is species-specific. Detailed chemical analysis revealed the presence of fatty acid derivatives other than aldehydes such as hydroxyacids, ketoacids, oxoacids and epoxyalcohols, increasing the complexity of a chemical defence of diatoms mediated only by aldehydes. All these compounds belong to a class of compounds called oxylipins, that are oxygenated compounds biosynthesized from fatty acids by oxygenasecatalyzed oxygenation. Marine diatoms are able to produce the major antiproliferative oxylipins by a novel oxygenase-dependent oxidation of C16 fatty acids hexadecatrienoic acid (16:3 (w-4) and hexadecatetrenoic acid (16:4 (w-1), and C2o eicosapentaenoic acid (20:5 (w-3). This process is triggered by lypolitic acyl hydrolase activity, that feeds the downstream lipoxygenase pathway. The ecological meaning of the oxylipin pathway in the diatom-copepod interactions is discussed, showing that attention should move from single compounds to complex biochemical process. The deleterious effect on copepod reproduction could be due to a biochemical process such as the generation of an high oxidative potential, rather than only by aldehydes or other secondary oxygenated products, that when present can co-occur to produce the final effect

Evaluating remote setting techniques for oyster (Crassostrea virginica) seed production in Louisiana

Research was conducted to implement remote setting technology for the commercial- scale production of oysters on alternative cultch material in Louisiana. Genetic research has created an enhanced oyster stock for commercial cultivation. Since the Louisiana oyster industry relies on natural seed production for product, they are unable to utilize these new advances and are never guaranteed a reliable source of oyster seed. Remote setting is one way of producing a consistent supply of genetically improved oysters. Cultch material for oyster settlement is a limiting resource. Several alternatives to clamshell have been explored. The objectives of this study are: (1) test larval setting success (penetration) using three cultch types in aerated and non-aerated treatments; (2) characterize triploid oyster seed growth and abundance among three cultch types on a commercial oyster lease; (3) characterize ploidy dilution of planted triploid oyster seed by natural diploids among three cultch types on an oyster lease; and (4) document the costs associated with seed bedding. Limestone had significantly less spat set than both whole and crushed oyster shell; spat set significantly less at bottom-depth and mid-depth in non-aerated compared to aerated treatments (objective 1). This shows the importance of aeration for spat settlement distribution among depths. Oyster growth was significantly less on limestone compared to both whole and crushed shell (objective 2). Spat on limestone were limited in two dimensional growing space. Of the fifty individuals sampled from each cultch type for percent triploidy, 2%, 4% and 8% were triploid for crushed shell, limestone and whole shell, respectively; all cultch types showed at least 92% diploid dilution (objective 3). These results are based on one site and season, therefore cannot be used to make conclusions about overall practicality for oyster production in Louisiana. The cost associated with seed bedding is $6.00 per barrel (objective 4). Whole oyster shell had significantly more initial spat set and growth than limestone. There was no significant difference in oyster abundance among all cultch types

The Denial of Innocence: Implicit Racial Biases and Judgments of Child Behavior based on Brief Observations

Studies on racial bias highlight disparities in negative judgments faced by People of Color (Hinton, 2017) as compared to their White counterparts, and some disparities may be apparent even in childhood. The present study employed an experimental design to examine the impact of child race on participant judgments of child behavior based on brief observations. Students participated and were randomly assigned to one of two conditions involving brief video observations. In the first condition, the target child was Black and in the second, the target was White. Targets were matched in terms of age, socioeconomic status, and expert-rated level of problem behavior. After watching the brief video, participants provided ratings of child behavior using the Conners Teacher Rating Scale- Revised (CTRS-R). A MANCOVA that included participant demographic covariates indicated a statistically significant impact of condition on behavior ratings. Univariate tests and descriptive statistics suggested that the ratings of participants who viewed a Black child were higher for overall problem behavior and for oppositional behavior. The covariate of participant race/ethnicity also statistically predicted ratings, with Black/African American status predicting lower overall problem behavior ratings. Implications concern understanding the impact of implicit racial biases for Children of Color, and furthering efforts to end racism and promote social justice

Perspectives on procedure based assessments: a thematic analysis of semi-structured interviews with ten UK surgical trainees

Objectives: The introduction of competency-based training has necessitated development and implementation of accompanying mechanisms for assessment. Procedure based assessments (PBAs) are an example of workplace-based assessments that are used to examine focal competencies in the workplace. The primary objective was to understand surgical trainees’ perspective on the value of PBA. Design: Semi-structured interviews with 10 surgical trainees individually interviewed to explore their views. Interviews were audio-recorded and transcribed, following this they were open and axial coded. Thematic analysis was then performed. Results: Semi-structured interviews yielded several topical and recurring themes. In trainees’ experience the use of PBAs as a summative tool limits their educational value. Trainees reported a lack of support from seniors and variation in the usefulness of the tool based on stage of training. Concerns related to the validity of PBAs for evaluating trainees’ performance with reports of ‘gaming’ the system and trainees completing their own assessments. Trainees’ did identify the significant value of PBAs when used correctly. Benefits included the identification of additional learning opportunities, standardisation of assessment and their role in providing a measure of progress. Conclusions: The UK surgical trainees interviewed identified both limitations and benefits to PBAs, however we would argue based on their responses and our experience that their use as a summative tool limits their formative use as an educational opportunity. PBAs should either be used exclusively to support learning or solely used as a summative tool, if so further work is needed to audit, validate and standardise them for this purpose