Optical control of an atomic inner-shell x-ray laser

X-ray free-electron lasers have had an enormous impact on x-ray science by achieving femtosecond pulses with unprecedented intensities. However, present-day facilities operating by the self-amplified spontaneous emission (SASE) principle have a number of shortcomings, namely, their radiation has a chaotic pulse profile and short coherence times. We put forward a scheme for a neon-based atomic inner-shell x-ray laser (XRL) which produces temporally and spatially coherent subfemtosecond pulses that are controlled by and synchronized to an optical laser with femtosecond precision. We envision that such an XRL will allow for numerous applications such as nuclear quantum optics and the study of ultrafast quantum dynamics of atoms, molecules, and condensed matter.Comment: 8 pages, 5 figures, RevTeX4.1, revise

Under the Hood: An (Auto) Ethnographic Study of How White Adolescent Males Critically Engage with Race in Grand Theft Auto V

Grand Theft Auto V (GTA V) is emblematic of the public controversies that associate video games with violence, misogyny, and damaging depictions of race and gender. However, it is also a layered referential and self-reflexive text that roundly critiques US culture, including the pernicious complicity of media on issues of identity. GTA V is the third best selling video game in history, and primarily targets white adolescent males, but its effects on the attitudes and behaviors of its chief consumers are virtually unstudied. Furthermore, the tendency for schools to keep controversial games at a distance may neglect a need to better equip adolescent boys with the tools to critically consume the complex media in which they are immersed. This doctoral dissertation employs a postcolonial lens and documents a month-long qualitative study where a high school class of ten white adolescent boys played GTA V while in a formal instructional context that encouraged them to critically reflect on their gameplay. Although they viewed the game through the lenses of gender, masculinities, violence, and hegemony, my research specifically reports on how they engaged with representations of race and racialized places in the elaborate urban simulation. The participants were positioned as co-researchers and trained in basic ethnographic methods, and the fieldnotes and filmed videos of their play were synthesized in autoethnographic accounts of their experiences. Data was also gathered from pre- and post-surveys, filmed classroom sessions, a private Facebook group, the counter-hegemonic media they produced, and their notes and videos. The investigation revealed that participants naturalized racial stereotypes and problematic connections of race and place. And, the instructional approach was found to provoke a greater awareness about discriminatory depictions of race in the game and, in some cases, media at large. Some also become aware of their own tendencies to appropriate commodified forms of blackness. Finally, their discourse and views were found to be largely shaped by media, highlighting the need for a greater emphasis on media literacy in schools

Mapping Mendelian traits in asexual progeny using changes in marker allele frequency

Linkage between markers and genes that affect a phenotype of interest may be determined by examining differences in marker allele frequency in the extreme progeny of a cross between two inbred lines. This strategy is usually employed when pooling is used to reduce genotyping costs. When the cross progeny are asexual, the extreme progeny may be selected by multiple generations of asexual reproduction and selection. We analyse this method of measuring phenotype in asexual progeny and examine the changes in marker allele frequency due to selection over many generations. Stochasticity in marker frequency in the selected population arises due to the finite initial population size. We derive the distribution of marker frequency as a result of selection at a single major locus, and show that in order to avoid spurious changes in marker allele frequency in the selected population, the initial population size should be in the low to mid hundreds

Haplotype Probabilities in Advanced Intercross Populations

Advanced intercross populations, in which multiple inbred strains are mated at random for many generations, have the advantage of greater precision of genetic mapping because of the accumulation of recombination events across the multiple generations. Related designs include heterogeneous stock and the diversity outcross population. In this article, I derive the two-locus haplotype probabilities on the autosome and X chromosome with these designs. These haplotype probabilities provide the key quantities for developing hidden Markov models for the treatment of missing genotype information. I further derive the map expansion in these populations, which is the frequency of recombination breakpoints on a random chromosome

The variance of identity-by-descent sharing in the Wright-Fisher model

Widespread sharing of long, identical-by-descent (IBD) genetic segments is a hallmark of populations that have experienced recent genetic drift. Detection of these IBD segments has recently become feasible, enabling a wide range of applications from phasing and imputation to demographic inference. Here, we study the distribution of IBD sharing in the Wright-Fisher model. Specifically, using coalescent theory, we calculate the variance of the total sharing between random pairs of individuals. We then investigate the cohort-averaged sharing: the average total sharing between one individual and the rest of the cohort. We find that for large cohorts, the cohort-averaged sharing is distributed approximately normally. Surprisingly, the variance of this distribution does not vanish even for large cohorts, implying the existence of "hyper-sharing" individuals. The presence of such individuals has consequences for the design of sequencing studies, since, if they are selected for whole-genome sequencing, a larger fraction of the cohort can be subsequently imputed. We calculate the expected gain in power of imputation by IBD, and subsequently, in power to detect an association, when individuals are either randomly selected or specifically chosen to be the hyper-sharing individuals. Using our framework, we also compute the variance of an estimator of the population size that is based on the mean IBD sharing and the variance in the sharing between inbred siblings. Finally, we study IBD sharing in an admixture pulse model, and show that in the Ashkenazi Jewish population the admixture fraction is correlated with the cohort-averaged sharing.Comment: Includes Supplementary Materia

Multiple Quantitative Trait Loci Influence the Shape of a Male-Specific Genital Structure in Drosophila melanogaster

The observation that male genitalia diverge more rapidly than other morphological traits during evolution is taxonomically widespread and likely due to some form of sexual selection. One way to elucidate the evolutionary forces acting on these traits is to detail the genetic architecture of variation both within and between species, a program of research that is considerably more tractable in a model system. Drosophila melanogaster and its sibling species, D. simulans, D. mauritiana, and D. sechellia, are morphologically distinguishable only by the shape of the posterior lobe, a male-specific elaboration of the genital arch. We extend earlier studies identifying quantitative trait loci (QTL) responsible for lobe divergence across species and report the first genetic dissection of lobe shape variation within a species. Using an advanced intercross mapping design, we identify three autosomal QTL contributing to the difference in lobe shape between a pair of D. melanogaster inbred lines. The QTL each contribute 4.6–10.7% to shape variation, and two show a significant epistatic interaction. Interestingly, these intraspecific QTL map to the same locations as interspecific lobe QTL, implying some shared genetic control of the trait within and between species. As a first step toward a mechanistic understanding of natural lobe shape variation, we find an association between our QTL data and a set of genes that show sex-biased expression in the developing genital imaginal disc (the precursor of the adult genitalia). These genes are good candidates to harbor naturally segregating polymorphisms contributing to posterior lobe shape

Szubjektív jóllét a mintaadó pedagógusok körében - coping stratégiák, egészségmagatartás és egészségi állapot vizsgálata

Among the biological, environmental factors and the health care system parameters which influence human health, it is of most importance to emphasize the role of lifestyle as the fourth influencing pillar of health. Throughout lifetime, the organism has to face positive and negative stressors, however, the quality of adaptation determines the consequence that stress evokes. Chronic stress might lead to morbidities that affect several organ systems, therefore the use of highly efficacious coping strategies is essential. Preventive lifestyle elements decrease the development of morbidities, and also possess the benefit of health care system expenditure reduction. Health maintenance habits are mostly evolved by early adulthood, and typically only modified by occurrence of serious illnesses (e.g. heart disease, cancer). By transmitting values and serving as models, pedagogues contribute to socialisation significantly. In my research, I aimed to investigate the extent of stress a pedagogue has to face as well as characterize their coping strategies. In 5 secondary schools 79 individuals were enrolled into the study using a personally asked or self-completed questionnaire. My results show that preventive health behaviour is not only accompanied by a higher level of general satisfaction and happiness, but also by a better subjective health status. Physically passive teachers reported lower rates of satisfaction and happiness. More than half of the respondents go in for sports regularly, and a majority aspires to keep a healthy diet In terms of coping strategies, problem-focused methods are characteristic. It is a cause for concern that the incidence of morbidities was higher in the group of teachers reporting higher stress-levels