A2_3 The Great Eggscape

The movie “Chicken Run” sees a flock of chickens escape certain death by building an aircraft and flying out. By estimating the dimensions of this craft, “The Old Crate”, we calculated that atakeoff speed of 36ms−1 would be required for flight, which gave a kinetic energy of 130 KJ. Reviewing the movie showed that a total of 40 chickens power the craft through pedalling. Assuming 100% efficiency we calculated that the chickens could only supply 3.2 KJ of energy, hence, would not in fact escape their fate

Characterization of a Temperature-Sensitive Vertebrate Clathrin Heavy Chain Mutant as a Tool to Study Clathrin-Dependent Events In Vivo

Clathrin and clathrin-dependent events are evolutionary conserved although it is believed that there are differences in the requirement for clathrin in yeast and higher vertebrates. Clathrin is a long-lived protein and thus, with clathrin knockdowns only long-term consequences of clathrin depletion can be studied. Here, we characterize the first vertebrate temperature-sensitive clathrin heavy chain mutant as a tool to investigate responses to rapid clathrin inactivation in higher eukaryotes. Although we created this mutant using a clathrin cryo-electron microscopy model and a yeast temperature-sensitive mutant as a guide, the resulting temperature-sensitive clathrin showed an altered phenotype compared to the corresponding yeast temperature-sensitive clathrin. First, it seemed to form stable triskelions at the non-permissive temperature although endocytosis was impaired under these conditions. Secondly, as a likely consequence of the stable triskelions at the non-permissive temperature, clathrin also localized correctly to its target membranes. Thirdly, we did not observe missorting of the lysosomal enzyme beta-glucuronidase which could indicate that the temperature-sensitive clathrin is still operating at the non-permissive temperature at the Golgi or, that, like in yeast, more than one TGN trafficking pathway exists. Fourthly, in contrast to yeast, actin does not appear to actively compensate in general endocytosis. Thus, there seem to be differences between vertebrates and yeast which can be studied in further detail with this newly created tool

A2_1 Zeus' Lightning Bolt

In this paper we calculate the heat capacity that would be required for the mythological Greek god Zeus to be able to comfortably hold a, hypothetical, `stationary lightning bolt'. Known properties of lightning and the human pain threshold were used to model the specic heat capacity required to elevate Zeus' hand temperature, from ambient to the upper limit of pain. In order for Zeus to be able to hold the lightning bolt, the calculated specic heat capacity that his hand must have was 3:33 * 10^10 J Kg-1 K-

A2_5 Black hole Sun

This paper investigates what would happen if a planet’s host star was instantaneously replaced by a black hole of equal radius. It was found that the mass of a black hole needed to ensure near enough instantaneous absorption of the original host star is 2.3×108 M. Latterly some other consequences of the new Black hole Sun have also been explored

Identification of a cytoplasmic motif in the erythropoietin receptor required for receptor internalization

AbstractErythropoietin (EPO) promotes the viability, proliferation and differentiation of mammalian erythroid progenitor cells via its specific cell surface receptor. The EPO receptor (EPO-R) is a member of the cytokine receptor superfamily and is comprised of one identified subunit which homodimerizes upon ligand binding. To study the role of the intracellular domain of the EPO-R in the endocytosis of EPO, we compared the rate and extent of 125I-EPO endocytosis by wild type (wt) EPO-R and five cytoplasmically truncated EPO-Rs: 1–251 EPO-R, 1–257 EPO-R, 1–267 EPO-R, 1–276 EPO-R and 1–306 EPO-R which contain 4, 10, 20, 29 or 59 amino acids of the cytoplasmic domain, respectively. We also studied an EPO-R mutant (PB) which lacks amino acid residues 281–300 of the cytoplasmic domain. The experiments were conducted in COS 7 cells transfected with the EPO-R cDNAs and in Ba/F3 cells stably expressing the wt EPO-R, 1–251 or 1–257 EPO-R. Cells expressing wt EPO-R, PB EPO-R (Δ281–300), 1–276 EPO-R or 1–306 EPO-R internalized approximately 50% of 125I-EPO bound to the cell surface, while cells expressing 1–251, 1–257 or 1–267 EPO-R internalized only 25% of the bound 125I-EPO. The steady-state expression levels of these latter receptors on the cell surface were typically 2–5-fold higher than wt EPO-R. Our data indicate that amino acid residues 267–276 (FEGLFTTHK) of the EPO-R cytoplasmic domain may have a role in receptor internalization. Metabolic labeling experiments suggest that in transiently transfected COS 7 cells most of the wt EPO-R and 1–257 EPO-Rs do not exit the ER and may be degraded there. The half-life of both receptors was essentially similar and was in the range of 1 h. In Ba/F3 cells the mature Golgi processed 1–257 EPO-R was more stable than the corresponding form of the wt EPO-R, possibly contributing to its higher cell surface expression

Role of Classroom Teachers in Nutrition and Physical Education

Nutrition education and physical education in schools is increasingly being explored as a way to prevent childhood overweight and to promote healthy eating and physical activity habits behaviors. Classroom teachers are often responsible for providing this education. The current study examined the roles and perspectives of elementary school teachers regarding student nutrition, nutrition education, and physical education. Data is from a 2001-2002 study of the Los Angeles Unified School District (LAUSD) Nutrition Network. Analyses were based on 78 structured interviews with elementary school teachers. Results showed that teachers perceive their role in nutrition education as teachers, role models, advocates, and motivators. Teachers integrate nutrition education into existing subject areas, and believe that nutrition education results in greater knowledge and healthier food choices. However, teachers report that too little time is spent on nutrition education. Results of this study also indicate that classroom teachers are often responsible for physical education (PE). Teachers believe PE has a positive effect on the school community and on student fitness, but the effect is limited due to lack of structure and lack of time in PE class. Teachers report barriers to both nutrition education and physical education, including other classes taking up too much time, limited teacher training, and a lack of adequate equipment and facilities. Findings suggest that more resources including teacher training, time, curricula and textbooks, and equipment need to be allocated for nutrition education and physical education at the elementary school level

LASER treatment in gynaecology -A randomized controlled trial in women with symptomatic lichen sclerosus.

OBJECTIVE Aim of our study was to evaluate the therapeutic effect of laser treatment in vulvar lichen sclerosus, mainly the reduction of existing symptoms as itching, burning and pain. We asked about the different outcome by using different application doses. STUDY DESIGN We conducted a prospective randomized double-blind dose-controlled trial in our dysplasia unit specializing vulvar disorders. 67patients with active LS were included. LS was confirmed by biopsy or by the validated CSS (clinical scoring system of vulvar LS). Computer generated randomization resulted in two groups, each group received a different application dose.(LDG- low dose group, NDG- normal dose group) During the study period of 18 weeks all participants received three laser applications in three subsequent sessions of three weeks. Two follow-ups six and twelve weeks after the first application was performed. At every visit, the participants filled in the VAS (visual analogue scale) for recording the actual vulvar symptoms as itching burning or pain on a range from 0 to 10. RESULTS Before treatment the mean VAS-Score was 4.3 (STD ± 2.4) in the NDG and 5.1(±2.6) in the LDG. After 18 weeks, the mean reduction was -2.4 (±2.3) for NDG and -2.7 (±2.8) for LDG. Four patients (two of each group) reported more pain after than before treatment. Both groups show significant lower VAS-Scores 18 weeks after the treatment than before therapy (p < 0.0001). The reduction of symptoms after 18 weeks between NDG and LDG was not significant (p = 0.6244). CONCLUSION Laser treatment with the microablative CO2 laser leads to a significant improvement for symptoms of LS. A higher dosage of laser radiation shows no benefit concerning the symptoms. We have not observed any serious adverse events during this study