The chemical evolution of gas-rich dwarf galaxies

A numerical double burst model of the chemical evolution of gas-rich dwarf galaxies has been developed. The model is fitted to a sample of N/O, O/H, Y and gas fraction observations, where N/O and O/H are the relative abundances by number of nitrogen to oxygen and oxygen to hydrogen, respectively. Y is the abundance by mass of helium. Closed models as well as models including enriched outflow, ordinary outflow and ordinary outflow combined with inflow are considered.The bursts are assumed to be instantaneous but ordered in pairs to explain the scatter in N/O-O/H. The method of gas fraction fitting is revised, and it is found that it is very important to specify whether dwarf irregulars (dIrrs) or blue compact galaxies (BCGs) are considered. Effective enriched winds fail when fitting N/O, whereas closed models, models with ordinary winds or a combination of ordinary winds and inflow are all viable.Comment: 22 pages, 25 figures, MNRAS LaTeX forma

Running quark mass in two flavor QCD

We present first results for the step scaling function sigma_P of the renormalization factor Z_P of the pseudoscalar density. The simulations are performed within the framework of the Schroedinger functional with two flavors of O(a) improved Wilson fermions. The knowledge of sigma_P is required to compute the renormalization group invariant quark masses. We also study the performance of a variant of the HMC algorithm using two pseudofermion fields.Comment: 3 pages, 2 figures, Lattice2002(spectrum

Bacillus thuringiensis DB27 Produces Two Novel Protoxins, Cry21Fa1 and Cry21Ha1, Which Act Synergistically against Nematodes

Bacillus thuringiensis has been widely used as a biopesticide, primarily for the control of insect pests, but some B. thuringiensis strains specifically target nematodes. However, nematicidal virulence factors of B. thuringiensis are poorly investigated. Here, we describe virulence factors of nematicidal B. thuringiensis DB27 using Caenorhabditis elegans as a model. We show that B. thuringiensis DB27 kills a number of free-living and animal-parasitic nematodes via intestinal damage. Its virulence factors are plasmid-encoded Cry protoxins, since plasmid-cured derivatives do not produce Cry proteins and are not toxic to nematodes. Whole-genome sequencing of B. thuringiensis DB27 revealed multiple potential nematicidal factors, including several Cry-like proteins encoded by different plasmids. Two of these proteins appear to be novel and show high similarity to Cry21Ba1. Named Cry21Fa1 and Cry21Ha1, they were expressed in Escherichia coli and fed to C. elegans, resulting in intoxication, intestinal damage, and death of nematodes. Interestingly, the effects of the two protoxins on C. elegans are synergistic (synergism factor, 1.8 to 2.5). Using purified proteins, we determined the 50% lethal concentrations (LC50s) for Cry21Fa1 and Cry21Ha1 to be 13.6 μg/ml and 23.9 μg/ml, respectively, which are comparable to the LC50 of nematicidal Cry5B. Finally, we found that signaling pathways which protect C. elegans against Cry5B toxin are also required for protection against Cry21Fa1. Thus, B. thuringiensis DB27 produces novel nematicidal protoxins Cry21Fa1 and Cry21Ha1 with synergistic action, which highlights the importance of naturally isolated strains as a source of novel toxins

RDV Technology for Future European Space Missions

The development of a prototype on board software package for autonomous rende~vous operations belongs to one bf the key elements of ESA sponsored rendez~vous development activities in which MBB/ERNO is strongly involved. General guidelines~ control algorythms and the software.architecture, were principal tasks which have been completed before detailed de~ign,coding and. verification tests were started. lt is expected that the Columbus missions with enhanced EURECA, MTFF (Man tended free flyer) and HERMES will benefit from the experience gained from thi~ ESA RVD technology ~rogram. On orbit ser~icing of EURECA at the USSS or at the station . vicinity by NSTS will need partial or complete rendez-vous, capabilities

Changes of algal biomass as carbon, cell number and volume, in bottles suspended in Lake Constance

Changes of algal biomass, as carbon, cell numbers and volume were determined for phytoplankton of Lake Constance suspended in situ in 2 1 glass bottles. Phytoplankton placed at the 6% surface penetrating light level (photosynthetically available radiation) were close to the compensation depth for growth estimated as total paniculate carbon and total cell volumes. Cell counts of individual algal species however, showed appreciable growth of diatoms offset by the decline of flagellates. Bottles suspended at two shallower depths in a separate experiment showed some growth of all species and indicated a vertical niche separation of growth of Rhodomonas minuta Skuja and R. lens Dascher and Ruttner in accordance with their vertical distribution

New challenges in studying nutrition-disease interactions in the developing world.

Latest estimates indicate that nutritional deficiencies account for 3 million child deaths each year in less-developed countries. Targeted nutritional interventions could therefore save millions of lives. However, such interventions require careful optimization to maximize benefit and avoid harm. Progress toward designing effective life-saving interventions is currently hampered by some serious gaps in our understanding of nutrient metabolism in humans. In this Personal Perspective, we highlight some of these gaps and make some proposals as to how improved research methods and technologies can be brought to bear on the problems of undernourished children in the developing world

Pregnancy-associated breast cancer - Special features in diagnosis and treatment

For obvious psychological reasons it is difficult to associate pregnancy - a life-giving period of our existence with life-threatening malignancies. Symptoms pointing to malignancy are often ignored by both patients and physicians, and this, together with the greater difficulty of diagnostic imaging, probably results in the proven delay in the detection of breast cancers during pregnancy. The diagnosis and treatment of breast cancer are becoming more and more important, as the fulfillment of the desire to have children is increasingly postponed until a later age associated with a higher risk of carcinoma, and improved cure rates of solid tumors no longer exclude subsequent pregnancies. The following article summarizes the special features of the diagnosis and primary therapy of pregnancy-associated breast cancer with particular consideration of cytostatic therapy

An exploratory investigation of food choice behavior of teenagers with and without food allergies

Background - Understanding food choice behavior in adolescence is important because many core eating habits may be tracked into adulthood. The food choices of at least 2.3% of teenagers living in the United Kingdom are determined by food allergies. However, the effect of food allergies on eating habits in teenagers has not yet been studied.Objective - To provide an understanding of how teenagers with food allergies make food choice decisions and how these differ from those of non–food-allergic teenagers.Methods - One focus group discussion with non–food-allergic teenagers (n = 11) and 14 semistructured interviewers (7 with food-allergic and 7 with non–food-allergic teenagers) were performed (age range, 12-18 years). The focus group discussion and interviews were audiorecorded, transcribed verbatim, and analyzed using thematic content analysis.Results - Teenagers from both groups (food-allergic and non–food-allergic) named sensory characteristics of foods as the main reason for choosing them. Some food-allergic teenagers downplayed their allergy and frequently engaged in risk-taking behavior in terms of their food choices. However, they reported difficulties in trying new foods, especially when away from home. Parental control was experienced as protective by those with food allergies, whereas non–food-allergic teenagers felt the opposite. Most teenagers, including food-allergic ones, expressed the wish to eat similar foods to their friends. Other themes did not vary between the 2 groups.Conclusion - Food-allergic teenagers strive to be able to make similar food choices to their friends, although differences to non–food-allergic teenagers exist. It is important to address these differences to improve their dietary management