Time-resolved impulse response of the magnetoplasmon resonance in a two-dimensional electron gas

We have used optically excited ultrashort electrical pulses to measure the magnetoplasmon resonance of a two-dimensional electron gas formed in an AlGaAs/GaAs heterostructure at frequencies up to 200 gigahertz. This is accomplished by incorporating the sample into a guided wave probe operating in a pumped (^{3}He) system. We are able to detect the resonance by launching a stimulus pulse in the guide, and monitoring the system response in a time resolved pump-probe arrangement. Data obtained from measurements yield resonant frequencies that agree with the magnetoplasmon dispersion relation.Comment: 4 pages, 4 figure

IL-22 mediates goblet cell hyperplasia and worm expulsion in intestinal helminth infection.

Type 2 immune responses are essential in protection against intestinal helminth infections. In this study we show that IL-22, a cytokine important in defence against bacterial infections in the intestinal tract, is also a critical mediator of anti-helminth immunity. After infection with Nippostrongylus brasiliensis, a rodent hookworm, IL-22-deficient mice showed impaired worm expulsion despite normal levels of type 2 cytokine production. The impaired worm expulsion correlated with reduced goblet cell hyperplasia and reduced expression of goblet cell markers. We further confirmed our findings in a second nematode model, the murine whipworm Trichuris muris. T.muris infected IL-22-deficient mice had a similar phenotype to that seen in N.brasiliensis infection, with impaired worm expulsion and reduced goblet cell hyperplasia. Ex vivo and in vitro analysis demonstrated that IL-22 is able to directly induce the expression of several goblet cell markers, including mucins. Taken together, our findings reveal that IL-22 plays an important role in goblet cell activation, and thus, a key role in anti-helminth immunity

Monolithic WDM Sources And Detectors For The Long Wavelength Fiber Band Based On An InP Grating Multiplexer/demultiplexer

Wavelength Division Multiplexed (WDM) networks are currently attracting considerable attention worldwide. Applications envisaged are wide-ranging - from computer back-plane interconnects and the telephone local loop, through local- and metropolitan- area networks, to wide-area networks involving advanced wavelength routing schemes [1, 2]

Antimalarial 4(1H)-pyridones bind to the Qisite of cytochromebc1

Cytochrome bc1 is a proven drug target in the prevention and treatment of malaria. The rise in drug-resistant strains of Plasmodium falciparum, the organism responsible for malaria, has generated a global effort in designing new classes of drugs. Much of the design/redesign work on overcoming this resistance has been focused on compounds that are presumed to bind the Qo site (one of two potential binding sites within cytochrome bc1) using the known crystal structure of this large membrane-bound macromolecular complex via in silico modeling. Cocrystallization of the cytochrome bc1 complex with the 4(1H)-pyridone class of inhibitors, GSK932121 and GW844520, that have been shown to be potent antimalarial agents in vivo, revealed that these inhibitors do not bind at the Qo site but bind at the Qi site. The discovery that these compounds bind at the Qi site may provide a molecular explanation for the cardiotoxicity and eventual failure of GSK932121 in phase-1 clinical trial and highlight the need for direct experimental observation of a compound bound to a target site before chemical optimization and development for clinical trials. The binding of the 4(1H)-pyridone class of inhibitors to Qi also explains the ability of this class to overcome parasite Qo-based atovaquone resistance and provides critical structural information for future design of new selective compounds with improved safety profiles

Bacteria from contaminated urban and hilly areas as a source of polyhydroxyalkanoates production

Polyhydroxyalkanoates (PHA) production and extraction of different bacterial strains isolated from contaminated urban and hilly areas was conducted. The 30 bacterial isolates were Gram negative andbelonged to Pseudomonas, Citrobacter, Klebsiella, Escherichia and Enterobacter genera. Bacterial level of resistance against antibiotics (Penicillin) and heavy metals (zinc, cadmium and copper) was determined. Bacterial isolates from contaminated urban areas were found to be more resistant. The screening for PHA production was done by the Sudan black staining. Among the urban area isolates, U17, U8 and U9 produced highest concentration of PHA (50.4, 40.6 and 37.9%) while in hilly areaisolates H8, H6 and H9 showed highest production (45.8, 42.4 and 37.6%) by SDS digestion method. The percentage production was lowered when the extraction was done by sodium hypochlorite digestion method. Selected bacterial strains were optimized for PHA production at different growth conditions that is, pH, temperature and carbon sources. Bacterial isolates U8, U17 and H8 produced maximum amount of PHA 74, 69 and 59%, respectively, at pH 7, 37°C and using cooking oil as carbon source after 72 h. PHA polymerase phaC1/C2 genes were successfully amplified from genomic DNA of three bacterial isolates showing 540 bp DNA fragment which confirmed the presence of phaC1/C2 gene presence. It showed that the corresponding bacterial isolates would have been able to synthesizemedium chain length PHA

Analysis of bacterial strains from contaminated and non-contaminated sites for the production of biopolymers

A total 18 strains were collected from non-contaminated and contaminated environments, and were purified. All purified strains were characterized for Gram reaction and biochemical analysis. Screening for bioplastic production was done by Sudan black staining. Strains isolated from non-contaminated sites showed no polyhydroxyalkanoate (PHA) production. Biochemical analysis showed that PHA producing strains belong to Pseudomonas, Citrobacter, Enterobacter, Klebsiella, Escherichia and Bacillus genera. PHA extraction was done by sodium hypochlorite digestion method. Strain MS2D showed maximum percentage (65%). Production of PHA was optimized for different temperatures and pH. Selected strains were also tested for exopolysaccharides (EPS) production on EPS detection medium by solvent precipitation method. Four out of nine strains exhibited EPS production ability. EPS production was also optimized for different temperatures and pH

Serum Complement C3 and C4 Levels in Relation to Diagnosis of Lupus Nephritis

Purpose: The main objective of this study was to measure serum complement C3 and C4 concentrations in patients of lupus nephritis to see if these simple measurements would give useful information to the clinician managing such patients.Method: A total of 52 samples were obtained from SLE patients, 17 suffering from lupus nephritis. All patients met the revised 1997 American College of Rheumatology criteria for SLE. Serum C3 and C4 concentrations were measured with single gel radioimmunodiffusion technique. Results: In lupus nephritis, C3 and C4 are generally correlated. Both C3 and C4 levels were decreased but C4 concentrations were more often and more profoundly depressed than C3 concentration. Conclusion: All patients of lupus nephritis with low C3 or C4 concentrations should have serial measurements performed and selected patients will need a full complement profile, including measurement of alternate pathway components and total hemolytic pathway. Keywords: Systemic lupus erythematosus, Auto antibodies, Lupus nephritis, C3 and C4Tropical Journal of Pharmaceutical Research Vol. 7(4) 2008: pp. 1117-112

Cell morphology governs directional control in swimming bacteria

The ability to rapidly detect and track nutrient gradients is key to the ecological success of motile bacteria in aquatic systems. Consequently, bacteria have evolved a number of chemotactic strategies that consist of sequences of straight runs and reorientations. Theoretically, both phases are affected by fluid drag and Brownian motion, which are themselves governed by cell geometry. Here, we experimentally explore the effect of cell length on control of swimming direction. We subjected Escherichia coli to an antibiotic to obtain motile cells of different lengths, and characterized their swimming patterns in a homogeneous medium. As cells elongated, angles between runs became smaller, forcing a change from a run-and-tumble to a run-and-stop/reverse pattern. Our results show that changes in the motility pattern of microorganisms can be induced by simple morphological variation, and raise the possibility that changes in swimming pattern may be triggered by both morphological plasticity and selection on morphology

Comparative genomic and proteomic analyses of PE/PPE multigene family of Mycobacterium tuberculosis H₃₇Rv and H₃₇Ra reveal novel and interesting differences with implications in virulence

Tuberculosis, caused by Mycobacterium tuberculosis, remains a leading infectious disease taking one human life every 15 s globally. The two well-characterized strains H37Rv and H37Ra, derived from the same parental strain M. tuberculosis H37, show dramatically different pathogenic phenotypes. PE/PPE gene family, comprising of 176 open reading frames and present exclusively in genus Mycobacterium, accounts for ∼10% of the M. tuberculosis genome. Our comprehensive in silico analyses of PE/PPE family of H37Ra and virulent H37Rv strains revealed genetic differences between these strains in terms of several single nucleotide variations and InDels and these manifested in changes in physico-chemical properties, phosphorylation sites, and protein: protein interacting domains of the corresponding proteomes. Similar comparisons using the 13 sigma factor genes, 36 members of the mammalian cell entry family, 13 mycobacterial membrane protein large family members and 11 two-component signal transduction systems along with 5 orphaned response regulators and 2 orphaned sensor kinases failed to reveal very significant difference between H37Rv and H37Ra, reinforcing the importance of PE/PPE genes. Many of these changes between H37Rv and H37Ra can be correlated to differences in pathogenesis and virulence of the two strains

A new array concept using spatially distributed subarrays for unambiguous GNSS interference mitigation in automotive applications

Radio frequency interference (RFI) poses a severe problem for conventional GNSS receivers. Even low powered RFI can block the reception of satellite signals and prevent a position determination. Antenna array systems have been proven suitable to counteract RFI by incorporating spatial processing techniques. The large size of uniform rectangular arrays (URA) with half-wave antenna spacing impedes an installation in cars intended for the consumer mass market, where a hidden installation is a strict requirement by industry and customers. This paper introduces a new approach, where a conventional URA is split into distributed linear subarrays with the aim to reduce their footprint but to maintain the possibility of spatial processing. The achievable gain in robustness against RFI is evaluated. Drawbacks in terms of manifold ambiguities and their consequences for spatial processing techniques are also discussed. Furthermore, the accuracy of positioning results derived from a field test is put into context with a single antenna receiver