A quasispecies approach to the evolution of sexual replication in unicellular organisms

This study develops a simplified model describing the evolutionary dynamics of a population composed of obligate sexually and asexually reproducing, unicellular organisms. The model assumes that the organisms have diploid genomes consisting of two chromosomes, and that the sexual organisms replicate by first dividing into haploid intermediates, which then combine with other haploids, followed by the normal mitotic division of the resulting diploid into two new daughter cells. We assume that the fitness landscape of the diploids is analogous to the single-fitness-peak approach often used in single-chromosome studies. That is, we assume a master chromosome that becomes defective with just one point mutation. The diploid fitness then depends on whether the genome has zero, one, or two copies of the master chromosome. We also assume that only pairs of haploids with a master chromosome are capable of combining so as to produce sexual diploid cells, and that this process is described by second-order kinetics. We find that, in a range of intermediate values of the replication fidelity, sexually reproducing cells can outcompete asexual ones, provided the initial abundance of sexual cells is above some threshold value. The range of values where sexual reproduction outcompetes asexual reproduction increases with decreasing replication rate and increasing population density. We critically evaluate a common approach, based on a group selection perspective, used to study the competition between populations and show its flaws in addressing the evolution of sex problem.

Deadly Desire : A Psychoanalytical Reading of Desire and Death in the Poetry of Dylan Thomas

Dylan Thomas' work is often explored in light of the poet himself, and he has been referred to as modernism's l'enfant terrible or even described as a late romanticist. The aim in this essay is to explore the poetry without regard to his personal life as well as highlight previously ignored oedipal elements in said poetry. The main goal is to assert Thomas' place amongst the modernist literati, of which most were heavily influenced by Freud, as well as to be an acknowledgement of his work without considering his biography.

Bland äckliga fittor och kunskapsluckor : En kritisk analys av tonårstjejers sexuella agens och dess frigörande och diciplinerande potential, baserat på berättelser av barnmorskor och kuratorer

Ett använt begrepp när det gäller tonårstjejer och sexualitet är sexuell agens, att handla efter egna beslut. Avsikten med denna studie är att nå en ökad förståelse av vad som påverkar utvecklingen av sexuell agens hos tonårstjejer, utifrån berättelser av två professioner vid ungdomsmottagningar. Syftet är också att göra en kritisk analys och en sociologisk teoretisering av upplevelsen av sexuell agens samt utifrån ett maktperspektiv utreda dess disciplinerande och frigörande potential. Tidigare forskning visar främst att det finns en avsaknad av lust och kunskap hos tonårstjejer samt att deras förmåga att ta självständiga beslut i relation till sexualitet är avhängt deras agens. I denna studie genomfördes kvalitativa intervjuer med barnmorskor och kuratorer vid ungdomsmottagningar. Tematisk analysmetod användes vid tolkningsförfarandet. Det empiriska materialet visade bland annat att tonårstjejers agens är influerat av yttre påverkan, gränssättning, skam, självförtroende och kunskap. För att nå en sociologisk förståelse av det empiriska materialet har sociologiska perspektiv på sexualitet, makt samt Foucaults teori om kroppens disciplinering använts. Baserat på professionerna vid ungdomsmottagningarna visade analysen att utvecklingen av sexuell agens gynnas av kunskap och självförtroende, hämmas av påverkan och skam samt både gynnas och hämmas av gränssättning. Den fördjupade analysen visade att sexuell agens kan skapa autonoma beslut, vilket minskar sårbarheten för maktens disciplin och därmed verkar frigörande inom disciplinens egendefinierade gränser. En avslutande slutsats var att upplevelsen av sexuell agens bör förstås som främst disciplinerande.  

Knowledge and perceptions regarding sexual and reproductive health among high school students in Kathmandu, Nepal

Background: Nepal recently began teaching sexual education in the school system and has established youth friendly services in order to meet the need of increased sexual and reproductive knowledge among the youth. Objective: To examine the sexual and reproductive knowledge and perceptions among young people attending schools in Kathmandu. Method: A written questionnaire was distributed to 160 students, in a classroom environment, in four schools in Kathmandu. Results: Two thirds of the females and nearly 60% of the males knew that it was possible to get sexually transmitted infection (STI) during one sexual encounter and more than half of the students knew when in the menstrual cycle conception was more likely to occur . One third of the participants did not know that it was possible to become pregnant after having intercourse once. The males demonstrated less knowledge than the females regarding every aspect of sex and reproduction, with the exception of pregnancy prevention. Conclusion and clinical implications: For the youths in this study, it was more important to prevent unwanted pregnancies than to protect oneself from STIs. Establishment of a hotline on the internet, where personalized and confidential counselling can be offered may complement the comprehensive sexual education in schools.

Medical students’ knowledge, attitudes, and perceptions on contraceptive use and counselling : a cross-sectional survey in Maharashtra, India

Objectives. This study aimed to investigate the knowledge, attitudes and perceptionstowards contraceptive use and counselling among medical students in Maharashtra, India. Setting. Considerable global maternal mortality and morbidity could be avoided through theuse of effective contraception. In India, contraception services are frequently unavailable or there are obstacles to obtaining modern, reversible contraceptives. Participants. A cross-sectional descriptive study using a self-administered questionnaire was conducted among 1996 medical students in their fifth year of study at 27 medical colleges in the state of Maharashtra, India. Descriptive and analytical statistics interpreted the survey instrument and significant results were presented with 95% CI. Results. Respondents expressed a desire to provide contraceptive services. A few studentshad experienced training in abortion care. There were misconceptions about moderncontraceptive methods and the impact of sex education. Attitudes towards contraceptionwere mainly positive, premarital counselling was supported and the influence of traditional values and negative provider attitudes on services was recognised. Gender, area of upbringing and type of medical college did not change the results. Conclusions. Despite mostly positive attitudes towards modern contraceptives, sex education and family planning counselling, medical students in Maharashtra have misconceptions about modern methods of contraception. Preservice and in-service training in contraceptive counselling should be implemented in order to increase women's access to evidence-based maternal healthcare services.