Evolution of the Ionizing Background at High Redshifts

We use a Maximum-Likelihood analysis to constrain the value and evolution of the ionizing background for 2<z<4.5, taking account of possible systematic errors. (The paper has a more detailed abstract)Comment: 12 figures (9 of those double plots), 17 pages. Accepted by MNRA

Synthesis and Characterization of Naphthalenediimide-Functionalized Flavin Derivatives

Two acceptor–acceptor dyads have been synthesized featuring a flavin moiety and a naphthalenediimide (NDI) unit. The NDI unit is linked to the flavin through a short spacer group via either the N(3) or N(10) positions of the flavin. We have investigated the UV-Vis and redox properties of these multi-electron accepting systems which indicate that these materials display the collective properties of their component systems. Fluorescence spectroscopy measurements have revealed that their emission properties are dominated by the flavin unit

Redox-mediated reactions of vinylferrocene: Toward redox auxiliaries

Chemical redox reactions have been exploited to transform unreactive vinylferrocene into a powerful dienophile for the Diels–Alder reaction and reactive substrate for thiol addition reactions upon conversion to its ferrocenium state. We have further investigated the ability of these reactions to facilitate redox-auxiliary-like reactivity by further hydrogenolyisis of the Diels–Alder adduct to the corresponding cyclopentane derivative

Video analysis of events within chemical sensor networks

This paper describes how we deploy video surveillance techniques to monitor the activities within a sensor network in order to detect environmental events. This approach combines video and sensor networks in a completely different way to what would be considered the norm. Sensor networks consist of a collection of autonomous, self-powered nodes which sample their environment to detect anything from chemical pollutants to atypical sound patterns which they report through an ad hoc network. In order to reduce power consumption nodes have the capacity to communicate with neighbouring nodes only. Typically these communications are via radio waves but in this paper the sensor nodes communicate to a base station through patterns emitted by LEDs and captured by a video camera. The LEDs are chemically coated to react to their environment and on doing so emit light which is then picked up by video analysis. There are several advantages to this approach and to demonstrate we have constructed a controlled test environment. In this paper we introduce and briefly describe this environment and the sensor nodes but focus mainly on the video capture, image processing and data visualisation techniques used to indicate these events to a user monitoring the network

Some dielectric studies

Two methods of approach are current in the literature for the interpretation of dielectric relaxation. One is that due to Debye which assumes that the relaxation process has its origin in the retardation of molecular reorientation due to frictional forces acting on the molecule. The other treats dipole rotation as a rate process in which the dipole must acquire a certain amount of energy in order to surmount a barrier separating two equilibrium positions of orientation. The dielectric relaxation times of some large ketones have been determined at four temperatures using a cell which does not appear to have been used up to this time for measuring the dielectric constant and loss of low loss liquids. The molecules measured were selected because of their size and shape, five were ellipsoidal and one was disc-like. For the ellipsoidal molecules^ the position of the dipole within the molecule was varied to investigate its effect on the relaxation time. A number of equations, based on the Debye model, which attempt to, account for the size of molecular relaxation time are examined. It is found that only the Fischer equation is satisfactory in predicting the effects of dipole direction within the molecule. The experimentally measured activation energies for all the large molecules were found to be similar and only a little higher than those observed for smaller molecules. In an attempt to understand these values a model is proposed based on the energy expended by the molecule during its reorientation process. The approach leads to a method for predicting the effect of solvent on dielectric relaxation time. It is found that the relaxation time depends exponentially on the internal pressure of the medium surrounding the relaxing species, and the activation energy can be accounted for in terms of the product of an activation volume and the internal pressure. From the activation volume an estimate is obtained of the angle through which the dipole rotates. For small molecules it is found that the angle is of the order of 20 degrees which indicates a fairly large jump accompanying the reorientation. For the larger molecules, however, the angle is much smaller, hence, the behaviour resembles Brownian rotational diffusion

Effects of 28 days of resistance exercise and consuming a commercially available pre-workout supplement, NO-Shotgun®, on body composition, muscle strength and mass, markers of satellite cell activation, and clinical safety markers in males

This study determined the effects of 28 days of heavy resistance exercise combined with the nutritional supplement, NO-Shotgun(R) on body composition, muscle strength and mass, markers of satellite cell activation, and clinical safety markers

Interplay between attenuation- and virulence-factors of Babesia Bovis and their contribution to the establishment of persistent infections in cattle

Bovine babesiosis is an acute and persistent tick-borne global disease caused mainly by the intraerythrocytic apicomplexan parasites Babesia bovis and B. bigemina. B. bovis infected erythrocytes sequester in blood capillaries of the host (cytoadhesion), causing malaria-like neurological signs. Cytoadhesion and antigenic variation in B. bovis are linked to the expression of members of the Variant Erythrocyte Surface Antigen (VESA) gene family. Animals that survive acute B. bovis infection and those vaccinated with attenuated strains remain persistently infected, suggesting that B. bovis parasites use immune escape mechanisms. However, attenuated B. bovis parasites do not cause neurological signs in vaccinated animals, indicating that virulence or attenuation factors play roles in modulating parasite virulence phenotypes. Artificial overexpression of the SBP2t11 protein, a defined attenuation factor, was associated with reduced cytoadhesion, suggesting a role for this protein as a key modulator of virulence in the parasite. Hereby, we propose a model that might be functional in the modulation of B. bovis virulence and persistence that relies on the interplay among SBP2t, VESA proteins, cytoadhesion, and the immune responses of the host. Elucidation of mechanisms used by the parasite to establish persistent infection will likely contribute to the design of new methods for the control of bovine babesiosis

Plasmodium falciparum FIKK Kinase Members Target Distinct Components of the Erythrocyte Membrane

BACKGROUND: Modulation of infected host cells by intracellular pathogens is a prerequisite for successful establishment of infection. In the human malaria parasite Plasmodium falciparum, potential candidates for erythrocyte remodelling include the apicomplexan-specific FIKK kinase family (20 members), several of which have been demonstrated to be transported into the erythrocyte cytoplasm via Maurer's clefts. METHODOLOGY: In the current work, we have knocked out two members of this gene family (Pf fikk7.1 and Pf fikk12), whose products are localized at the inner face of the erythrocyte membrane. Both mutant parasite lines were viable and erythrocytes infected with these parasites showed no detectable alteration in their ability to adhere in vitro to endothelial receptors such as chondroitin sulfate A and CD36. However, we observed sizeable decreases in the rigidity of infected erythrocytes in both knockout lines. Mutant parasites were further analyzed using a phospho-proteomic approach, which revealed distinct phosphorylation profiles in ghost preparations of infected erythrocytes. Knockout parasites showed a significant reduction in the level of phosphorylation of a protein of approximately 80 kDa for FIKK12-KO in trophozoite stage and a large protein of about 300 kDa for FIKK7.1-KO in schizont stage. CONCLUSIONS: Our results suggest that FIKK members phosphorylate different membrane skeleton proteins of the infected erythrocyte in a stage-specific manner, inducing alterations in the mechanical properties of the parasite-infected red blood cell. This suggests that these host cell modifications may contribute to the parasites' survival in the circulation of the human host