The Stability of Radiatively Cooled Jets in Three Dimensions

The effect of optically thin radiative cooling on the Kelvin-Helmholtz instability of three dimensional jets is investigated via linear stability theory and nonlinear hydrodynamical simulation. Two different cooling functions are considered: radiative cooling is found to have a significant effect on the stability of the jet in each case. The wavelengths and growth rates of unstable modes in the numerical simulations are found to be in good agreement with theoretical predictions. Disruption of the jet is found to be sensitive to the precessional frequency at the origin with lower frequencies leading to more rapid disruption. Strong nonlinear effects are observed as the result of the large number of normal modes in three dimensions which provide rich mode-mode interactions. These mode-mode interactions provide new mechanisms for the formation of knots in the flows. Significant structural features found in the numerical simulations appear similar to structures observed on protostellar jets.Comment: 32 pages, 13 figures, figures included in page tota

Influence of magnetic fields on pulsed, radiative jets

We present results of magnetohydrodynamic simulations of steady and time variable jets for a set of conditions applicable to outflows from young stellar objects (YSOs). As a first step in a detailed study of radiative magnetohydrodynamic jets, we study both steady and pulsed jets with a large-scale magnetic field oriented parallel to the jet flow axis. While toroidal components may be present in many jets, we have chosen in this initial study to focus solely on pure poloidal initial geometries. The range of magnetic field strengths studied is characterized by the dimensionless parameter beta = 8 pi P-gas/B-2 = 0.1-10(7). The results of our simulations show that the global characteristics are not strongly dependent on the strength of the magnetic field. Instead, we find that a predominantly poloidal field has more subtle effects, such as inhibiting instabilities, and increasing the "order" in the flow patterns. While the fields act to restrict "turbulent" gas motions, the pulse-induced internal shocks increase the likelihood of instabilities, complicate the global flow patterns, and increase the likelihood of magnetic reconnection. We detail the ways in which the magnetic pressure and tension forces affect the kinematics observed in these simulationsopen242

Computer aided synthesis: a game theoretic approach

In this invited contribution, we propose a comprehensive introduction to game theory applied in computer aided synthesis. In this context, we give some classical results on two-player zero-sum games and then on multi-player non zero-sum games. The simple case of one-player games is strongly related to automata theory on infinite words. All along the article, we focus on general approaches to solve the studied problems, and we provide several illustrative examples as well as intuitions on the proofs.Comment: Invitation contribution for conference "Developments in Language Theory" (DLT 2017

Distribution Analysis of Hydrogenases in Surface Waters of Marine and Freshwater Environments

Background Surface waters of aquatic environments have been shown to both evolve and consume hydrogen and the ocean is estimated to be the principal natural source. In some marine habitats, H2 evolution and uptake are clearly due to biological activity, while contributions of abiotic sources must be considered in others. Until now the only known biological process involved in H2 metabolism in marine environments is nitrogen fixation. Principal Findings We analyzed marine and freshwater environments for the presence and distribution of genes of all known hydrogenases, the enzymes involved in biological hydrogen turnover. The total genomes and the available marine metagenome datasets were searched for hydrogenase sequences. Furthermore, we isolated DNA from samples from the North Atlantic, Mediterranean Sea, North Sea, Baltic Sea, and two fresh water lakes and amplified and sequenced part of the gene encoding the bidirectional NAD(P)-linked hydrogenase. In 21% of all marine heterotrophic bacterial genomes from surface waters, one or several hydrogenase genes were found, with the membrane-bound H2 uptake hydrogenase being the most widespread. A clear bias of hydrogenases to environments with terrestrial influence was found. This is exemplified by the cyanobacterial bidirectional NAD(P)-linked hydrogenase that was found in freshwater and coastal areas but not in the open ocean. Significance This study shows that hydrogenases are surprisingly abundant in marine environments. Due to its ecological distribution the primary function of the bidirectional NAD(P)-linked hydrogenase seems to be fermentative hydrogen evolution. Moreover, our data suggests that marine surface waters could be an interesting source of oxygen-resistant uptake hydrogenases. The respective genes occur in coastal as well as open ocean habitats and we presume that they are used as additional energy scavenging devices in otherwise nutrient limited environments. The membrane-bound H2-evolving hydrogenases might be useful as marker for bacteria living inside of marine snow particles

Gender differences in best friendships

Prior investigations of friendship patterns have reported gender differences, with women's same-gender friendships tending to be richer and having a possible therapeutic value, as compared to those of men. Compared to same-gender best friendships, opposite-gender best friendships have been described as less fulfilling for women and more fulfilling for men. The present study explored such differences more fully in a sample of 65 female and 58 male predominantly white college students. Subjects completed four modified versions of P. H. Wright's [(1985) “The Acquaintance Description Form,” In S. F. Duck and D. Pearlman (Eds.), Understanding Personal Relationships: An Interdisciplinarian Approach, London: Sage] Acquaintance Description Form, describing their actual and ideal same-gender best friendships and their actual and ideal opposite-gender best friendships. They also responded to several measures of dysphoria. In the present study, the lowest scores for the friendship scales were reported by male subjects describing same-gender friendships, both ideal and actual. For both male and female subjects, dysphoria was positively correlated with a discrepancy between ideal and actual friendships with same-gender or opposite-gender individuals.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45601/1/11199_2004_Article_BF00289323.pd

Cardiac-Oxidized Antigens Are Targets of Immune Recognition by Antibodies and Potential Molecular Determinants in Chagas Disease Pathogenesis

Trypanosoma cruzi elicits reactive oxygen species (ROS) of inflammatory and mitochondrial origin in infected hosts. In this study, we examined ROS-induced oxidative modifications in the heart and determined whether the resultant oxidized cardiac proteins are targets of immune response and of pathological significance in Chagas disease. Heart biopsies from chagasic mice, rats and human patients exhibited, when compared to those from normal controls, a substantial increase in protein 4-hydroxynonenal (4-HNE), malondialdehyde (MDA), carbonyl, and 3-nitrotyrosine (3-NT) adducts. To evaluate whether oxidized proteins gain antigenic properties, heart homogenates or isolated cardiomyocytes were oxidized in vitro and one- or two-dimensional gel electrophoresis (2D-GE)/Western blotting (WB) was performed to investigate the proteomic oxidative changes and recognition of oxidized proteins by sera antibodies in chagasic rodents (mice, rats) and human patients. Human cardiomyocytes exhibited LD50 sensitivity to 30 µM 4-HNE and 100 µM H2O2 at 6 h and 12 h, respectively. In vitro oxidation with 4-HNE or H2O2 resulted in a substantial increase in 4-HNE- and carbonyl-modified proteins that correlated with increased recognition of cardiac (cardiomyocytes) proteins by sera antibodies of chagasic rodents and human patients. 2D-GE/Western blotting followed by MALDI-TOF-MS/MS analysis to identify cardiac proteins that were oxidized and recognized by human chagasic sera yielded 82 unique proteins. We validated the 2D-GE results by enzyme-linked immunosorbent assay (ELISA) and WB and demonstrated that oxidation of recombinant titin enhanced its immunogenicity and recognition by sera antibodies from chagasic hosts (rats and humans). Treatment of infected rats with phenyl-α-tert-butyl nitrone (PBN, antioxidant) resulted in normalized immune detection of cardiac proteins associated with control of cardiac pathology and preservation of heart contractile function in chagasic rats. We conclude that ROS-induced, cardiac-oxidized antigens are targets of immune recognition by antibodies and molecular determinants for pathogenesis during Chagas disease

Subaru IR Echelle Spectroscopy of Herbig-Haro Driving Sources. I. H2 and [Fe II] Emission

Peer reviewe