1,414 research outputs found
Empirical description of the hadron-hadron and hadron-nucleus interaction at the accelerator energy range
Taking into account several assumptions, a formula is transformed into two expressions for kaon and baryon plus antibaryon production in proton interaction and for pion production in pion interactions. Combining both formulae, expression are obtained for the spectrum of kaons and baryons plus antibaryons produced in the meson interactions. For analysis of the cosmic ray propagation in the atmosphere in actual fact, instead of the formulae for interactions of protons and mesons with protons, formulae appropriate for interactions with air nuclei was used. Using the method outlined among others by Elias et al. (1980) simple corrections were introduced to the derived expressions to account for the fact that the target is an air nucleus
Enhancement of deltamethrin degradation by soil bioaugmentation with two different strains of "Serratia marcescens"
Deltamethrin is one of the most commonly used pyrethroid in agricultural practice in different geographic regions of the world. It is detected in many environments, especially in soil and water, and can exhibit toxic effect to human and other organisms. In this study, we describe two bacterial strains DeI-1 and DeI-2, isolated from soil, and both identified as Serratia marcescens based on profile of the fatty acid methyl esters, biochemical test, and 16S RNA gene analysis, which were shown to efficiently degrade deltamethrin. Degradation of deltamethrin in mineral salt medium (50 mg l -1 ) proceeded by strains DeI-1 or DeI-2 reached the values of 88.3 or 82.8 % after 10 days, and DT50 was 2.8 or 4.0 days, respectively. Bioaugmentation of deltamethrin-contaminated non-sterile soils (100 mg kg -1 ) with strains DeI-1 or DeI-2 (3 × 10 6 cells g -1 of soil) enhanced the disappearance rate of pyrethroid, and its DT50 was reduced by 44.9, 33.1, 44.4, and 58.2 days or 39.1, 25.8, 35.6, and 46.0 days in sandy, sandy loam, silty loam, and silty soils, respectively, in comparison with non-sterile soils with only indigenous microflora. The three-way ANOVA indicated that DT50 of deltamethrin was significantly (P < 0.01) affected by soil type, microflora presence, and inoculum, and the interaction between these factors. Generally, the lower content of clay and organic carbon in soil, the higher degradation rate of deltamethrin was observed. Obtained results show that both strains of S. marcescens may possess potential to be used in bioremediation of deltamethrin-contaminated soils
Physical interaction between MYCN oncogene and polycomb repressive complex 2 (PRC2) in neuroblastoma: Functional and therapeutic implications
This article is made available through the Brunel Open Access Publishing Fund. © 2013 by The American Society for Biochemistry and Molecular Biology, Inc.CLU (clusterin) is a tumor suppressor gene that we have previously shown to be negatively modulated by the MYCN proto-oncogene, but the mechanism of repression was unclear. Here, we show that MYCN inhibits the expression of CLU by direct interaction with the non-canonical E box sequence CACGCG in the 5′-flanking region. Binding of MYCN to the CLU gene induces bivalent epigenetic marks and recruitment of repressive proteins such as histone deacetylases and Polycomb members. MYCN physically binds in vitro and in vivo to EZH2, a component of the Polycomb repressive complex 2, required to repress CLU. Notably, EZH2 interacts with the Myc box domain 3, a segment of MYC known to be essential for its transforming effects. The expression of CLU can be restored in MYCN-amplified cells by epigenetic drugs with therapeutic results. Importantly, the anticancer effects of the drugs are ablated if CLU expression is blunted by RNA interference. Our study implies that MYC tumorigenesis can be effectively antagonized by epigenetic drugs that interfere with the recruitment of chromatin modifiers at repressive E boxes of tumor suppressor genes such as CLU.SPARKS, The Neuroblastoma Society,
a Wellcome Trust grant (to A. S.), and the Italian Association for Cancer
Research
Stable isotopes in cave ice suggest summer temperatures in east-central Europe are linked to Atlantic Multidecadal Oscillation variability
The climate of east-central Europe (ECE) is the result of a combination of influences originating in the wider North Atlantic realm, the Mediterranean Sea, and the western Asian and Siberian regions. Previous studies have shown that the complex interplay between the large-scale atmospheric patterns across the region results in strongly dissimilar summer and winter conditions on timescales ranging from decades to millennia. To put these into a wider context, long-term climate reconstructions are required, but, largely due to historical reasons, these are lacking in ECE. We address these issues by presenting a high-resolution, radiocarbon-dated record of summer temperature variations during the last millennium in ECE, based on stable isotope analysis of a 4.84 m long ice core extracted from Focul Viu Ice Cave (Western Carpathians, Romania). Comparisons with both instrumental and proxy-based data indicate that the stable isotope composition of cave ice records the changes in summer air temperature and has a similar temporal evolution to that of the Atlantic Multidecadal Oscillation on decadal to multidecadal timescales, suggesting that changes in the North Atlantic are transferred, likely via atmospheric processes towards the wider Northern Hemisphere. On centennial timescales, the data show little summer temperature differences between the Medieval Warm Period (MWP) and the Little Ice Age (LIA) in eastern Europe. These findings are contrary to those that show a marked contrast between the two periods in terms of both winter and annual air temperatures, suggesting that cooling during the LIA was primarily the result of wintertime climatic changes
No Right to Remain Silent: Isolating Malicious Mixes
Mix networks are a key technology to achieve network anonymity and private messaging, voting and database lookups. However, simple mix network designs are vulnerable to malicious mixes, which may drop or delay packets to facilitate traffic analysis attacks. Mix networks with provable robustness address this drawback through complex and expensive proofs of correct shuffling but come at a great cost and make limiting or unrealistic systems assumptions. We present Miranda, an efficient mix-net design, which mitigates active attacks by malicious mixes. Miranda uses both the detection of corrupt mixes, as well as detection of faults related to a pair of mixes, without detection of the faulty one among the two. Each active attack -- including dropping packets -- leads to reduced connectivity for corrupt mixes and reduces their ability to attack, and, eventually, to detection of corrupt mixes. We show, through experiments, the effectiveness of Miranda, by demonstrating how malicious mixes are detected and that attacks are neutralized early
Variations in hepatic vascularisation: lack of a proper hepatic artery. Two case reports
The blood supply of the liver and other abdominal organs plays a significant
role during abdominal surgery. Knowledge of the most common patterns of
vascularisation should be broadened and new anomalies of the celiac trunk
and its branches dutifully reported. This paper presents two case reports which
describe the lack of a proper hepatic artery. Case 1 describes the cadaver of
a 64-year-old female in whom the right hepatic artery was observed to arise
from the common hepatic artery and run behind the portal vein. The common
hepatic artery was observed to be divided into three terminal vessels: the left
hepatic artery, the gastroduodenal artery, and the right gastric artery. Case 2
describes the cadaver of a 75-year-old male with a liver that was supplied from
3 different sources: the left hepatic artery from the left gastric artery (which
arose directly from the aorta), the right hepatic artery from the superior mesenteric
artery, and the middle hepatic artery from the common hepatic artery —
(branch of the hepato-splenic trunk). Moreover, the left inferior phrenic artery
arose from the left hepatic artery. (Folia Morphol 2011; 70, 2: 130–134
Simulating the Mammalian Blastocyst - Molecular and Mechanical Interactions Pattern the Embryo
Mammalian embryogenesis is a dynamic process involving gene expression and mechanical forces between proliferating cells. The exact nature of these interactions, which determine the lineage patterning of the trophectoderm and endoderm tissues occurring in a highly regulated manner at precise periods during the embryonic development, is an area of debate. We have developed a computational modeling framework for studying this process, by which the combined effects of mechanical and genetic interactions are analyzed within the context of proliferating cells. At a purely mechanical level, we demonstrate that the perpendicular alignment of the animal-vegetal (a-v) and embryonic-abembryonic (eb-ab) axes is a result of minimizing the total elastic conformational energy of the entire collection of cells, which are constrained by the zona pellucida. The coupling of gene expression with the mechanics of cell movement is important for formation of both the trophectoderm and the endoderm. In studying the formation of the trophectoderm, we contrast and compare quantitatively two hypotheses: (1) The position determines gene expression, and (2) the gene expression determines the position. Our model, which couples gene expression with mechanics, suggests that differential adhesion between different cell types is a critical determinant in the robust endoderm formation. In addition to differential adhesion, two different testable hypotheses emerge when considering endoderm formation: (1) A directional force acts on certain cells and moves them into forming the endoderm layer, which separates the blastocoel and the cells of the inner cell mass (ICM). In this case the blastocoel simply acts as a static boundary. (2) The blastocoel dynamically applies pressure upon the cells in contact with it, such that cell segregation in the presence of differential adhesion leads to the endoderm formation. To our knowledge, this is the first attempt to combine cell-based spatial mechanical simulations with genetic networks to explain mammalian embryogenesis. Such a framework provides the means to test hypotheses in a controlled in silico environment
Blastomeres arising from the first cleavage division have distinguishable fates in normal mouse development
Two independent studies have recently suggested similar models in which the embryonic and abembryonic parts of the mouse blastocyst become separated already by the first cleavage division. However, no lineage tracing studies carried out so far on early embryos provide the support for such a hypothesis. Thus, to re-examine the fate of blastomeres of the two-cell mouse embryo, we have undertaken lineage tracing studies using a non-perturbing method. We show that two-cell stage blastomeres have a strong tendency to develop into cells that comprise either the embryonic or the abembryonic parts of the blastocyst. Moreover, the two-cell stage blastomere that is first to divide will preferentially contribute its progeny to the embryonic part. Nevertheless, we find that the blastocyst embryonic-abembryonic axis is not perfectly orthogonal to the first cleavage plane, but often shows some angular displacement from it. Consequently, there is a boundary zone adjacent to the interior margin of the blastocoel that is populated by cells derived from both earlier and later dividing blastomeres. The majority of cells that inhabit this boundary region are, however, derived from the later dividing two-cell stage blastomere that contributes predominantly to the abembryonic part of the blastocyst. Thus, at the two-cell stage it is already possible to predict which cell will contribute a greater proportion of its progeny to the abembryonic part of the blastocyst (region including the blastocyst cavity) and which to the embryonic part (region containing the inner cell mass) that will give rise to the embryo proper
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