Group a streptococcal serotypes isolated from healthy schoolchildren in iran

Serotypes of group A streptococci are still a major cause of pharyngitis and some post-infectious sequelae such as rheumatic fever. As part of the worldwide effort to clarify the epidemiological pattern of group A streptococci in different countries, the present study was conducted to assess the prevalence of Streptococcus pyogenes serotypes in Iran. A total of 1588 throat swabs were taken from healthy school children in the city of Gorgan during February and March 1999. Of those isolates, 175 resulted positive for group A streptococci. The distribution pattern was similar for girls and boys, with 10.8 and 11.2, respectively. Urban school children showed a higher rate of colonization compared to those in rural areas. Serotyping was performed on 65 of the positive isolates using standard techniques, and only 21 (32) were M-type isolates. Their profiles fell into four types with M1 predominating, which could reflect the presence of rheumatic fever in the region. However, when isolates were challenged for T-antigen types, nearly all were positive (94). The pattern of T types was diverse (18 types), with the most common T types being T1 (26), TB3264 (15), TB\1-19 & B\25\1-19 (9.2) and T2 & 2\28 (7.7). When isolates were tested for opacity factor, only 23 (35) were positive while 34 (52) responded to the serum opacity reaction test. Although the number of isolates in this study was not sufficient to make any epidemiological conclusions, the scarcity of serotyping studies in Iran could render these data useful for future attempts to develop a streptococcal vaccine

A review of size and geometrical factors influencing resonant frequencies in metamaterials

Although metamaterials and so-called left-handed media have originated from theoretical considerations, it is only by their practical fabrication and the measurement of their properties that they have gained credibility and can fulfil the potential of their predicted properties. In this review we consider some of the more generally applicable fabrication methods and changes in geometry as they have progressed, exhibiting resonant frequencies ranging from radio waves to the visible optical region

Mid-Miocene cooling and the extinction of tundra in continental Antarctica

A major obstacle in understanding the evolution of Cenozoic climate has been the lack of well dated terrestrial evidence from high-latitude, glaciated regions. Here, we report the discovery of exceptionally well preserved fossils of lacustrine and terrestrial organisms from the McMurdo Dry Valleys sector of the Transantarctic Mountains for which we have established a precise radiometric chronology. The fossils, which include diatoms, palynomorphs, mosses, ostracodes, and insects, represent the last vestige of a tundra community that inhabited the mountains before stepped cooling that first brought a full polar climate to Antarctica. Paleoecological analyses, 40Ar/39Ar analyses of associated ash fall, and climate inferences from glaciological modeling together suggest that mean summer temperatures in the region cooled by at least 8°C between 14.07 ± 0.05 Ma and 13.85 ± 0.03 Ma. These results provide novel constraints for the timing and amplitude of middle-Miocene cooling in Antarctica and reveal the ecological legacy of this global climate transition

Effects of nematicides on nematode population densities and crop yield in a turnip-corn-pea cropping system

Nous avons évalué quatre systèmes de conduite de cultures lors d'une étude de 6 ans afin de lutter contre les nematodes dans un système annuel de production de navet-maïs-pois sur des parcelles de sable loameux Tifton naturellement infestées par les Meloidogyne spp. (environ 90 % de M. incognita et 10 % de M. hapla), les Pratylenchus spp. (environ 65 % de P. scribneri, 25 % de P. brachyurus et 10 % de P. zeae), ainsi que par les Paratrichodorus minor et Criconemella ornata. Le navet (Brassica campestris subsp. rapifera) a toléré de faibles quantités de tous les nematodes. Le maïs (Zea mays) 'Pioneer 3369A' a toléré de plus importantes quantités de tous les nematodes que le maïs 'Funks G-4507'. Les densités de population de juvéniles (J2) de Meloidogyne spp. ont été abaissées en deçà de 80 par 150 cm3 de sol par un mélange composé de 98 % de bromure de méthyle et 2 % de chloropicrine et par 20% de methyl isothiocyanate combiné à 80% d'hydrocarbones C3 chlorinés sur le navet et le maïs. Ces populations de nematodes ont augmenté rapidement chez le pois (Vigna unguiculata) 'Pinkeye purplehull' mais ce ne fut pas le cas chez le cultivar Worthmore. Les densités de populations des autres nematodes n'ont pas été affectées par le cultivar de pois ou par le nématicide, en l'occurrence l'ethoprop. Le fenamiphos a été plus efficace que l'ethoprop en abaissant les densités de nematodes. Les augmentations de rendement du système intensif de conduite des cultures se sont échelonnées de 4% à 52 % par rapport aux témoins non traités.Four management systems were evaluated in a six-year study to control nematodes in a turnip-corn-pea annual cropping System on plots of Tifton loamy sand naturally infested with Meloidogyne spp. (about 90 % M. incognita and 10% M. hapla), Pratylenchus spp. (about 65% P. scribneri, 25% P. brachyurus, and 10% P. zeae), Paratrichodorus minor and Criconemella ornata. Turnip (Brassica campestris subsp. rapifera) supported low numbers of all nematodes. 'Pioneer 3369A' corn (Zea mays) supported greater numbers of all nematodes than 'Funks G-4507'. Population densities of Meloidogyne spp. juveniles (J2) were suppressed below 80 per 150 cm3 of soil by 98 % methyl bromide + 2 % chloropicrin and 20 % methyl isothiocyanate + 80 % chlorinated C3 hydrocarbons on turnip and corn, and increased rapidly on 'Pinkeye purplehull', but not on a resistant cultivar, 'Worthmore' pea (Vigna unguiculata). Population densities of other nematodes were not affected by cultivar of pea or the nematicide, ethoprop. Fenamiphos was more effective than ethoprop in suppressing nematode population densities. Increases in crop yield in the intensive management system ranged from 4% to 52% over untreated controls

Intestinal fibrosis is reduced by early elimination of inflammation in a mouse model of IBD: Impact of a “Top‐Down” approach to intestinal fibrosis in mice

Background: The natural history of Crohn's disease follows a path of progression from an inflammatory to a fibrostenosing disease, with most patients requiring surgical resection of fibrotic strictures. Potent antiinflammatory therapies reduce inflammation but do not appear to alter the natural history of intestinal fibrosis. The aim of this study was to determine the relationship between intestinal inflammation and fibrogenesis and the impact of a very early “top‐down” interventional approach on fibrosis in vivo. Methods: In this study we removed the inflammatory stimulus from the Salmonella typhimurium mouse model of intestinal fibrosis by eradicating the S. typhimurium infection with levofloxacin at sequential timepoints during the infection. We evaluated the effect of this elimination of the inflammatory stimulus on the natural history of inflammation and fibrosis as determined by gross pathology, histopathology, mRNA expression, and protein expression. Results: Fibrogenesis is preceded by inflammation. Delayed eradication of the inflammatory stimulus by antibiotic treatment represses inflammation without preventing fibrosis. Early intervention significantly ameliorates but does not completely prevent subsequent fibrosis. Conclusions: This study demonstrates that intestinal fibrosis develops despite removal of an inflammatory stimulus and elimination of inflammation. Early intervention ameliorates but does not abolish subsequent fibrosis, suggesting that fibrosis, once initiated, is self‐propagating, suggesting that a very early top‐down interventional approach may have the most impact on fibrostenosing disease. (Inflamm Bowel Dis 2012;)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90367/1/21812_ftp.pd

The Volume of some Non-spherical Horizons and the AdS/CFT Correspondence

We calculate the volumes of a large class of Einstein manifolds, namely Sasaki-Einstein manifolds which are the bases of Ricci-flat affine cones described by polynomial embedding relations in C^n. These volumes are important because they allow us to extend and test the AdS/CFT correspondence. We use these volumes to extend the central charge calculation of Gubser (1998) to the generalized conifolds of Gubser, Shatashvili, and Nekrasov (1999). These volumes also allow one to quantize precisely the D-brane flux of the AdS supergravity solution. We end by demonstrating a relationship between the volumes of these Einstein spaces and the number of holomorphic polynomials (which correspond to chiral primary operators in the field theory dual) on the corresponding affine cone.Comment: 25 pp, LaTeX, 1 figure, v2: refs adde

Crystal structure of solid Oxygen at high pressure and low temperature

Results of X-ray diffraction experiments on solid oxygen at low temperature and at pressures up to 10 GPa are presented.A careful sample preparation and annealing around 240 K allowed to obtain very good diffraction patterns in the orthorhombic delta-phase. This phase is stable at low temperature, in contrast to some recent data [Y. Akahama et al., Phys. Rev. B64, 054105 (2001)], and transforms with decreasing pressure into a monoclinic phase, which is identified as the low pressure alpha-phase. The discontinuous change of the lattice parameters, and the observed metastability of the alpha-phase increasing pressure suggest that the transition is of the first order.Comment: 4 pages with three figure

Current and Spin-Torque in Double Tunnel Barrier Ferromagnet - Superconductor - Ferromagnet Systems

We calculate the current and the spin-torque in small symmetric double tunnel barrier ferromagnet - superconductor - ferromagnet (F-S-F) systems. Spin-accumulation on the superconductor governs the transport properties when the spin-flip relaxation time is longer than the transport dwell time. In the elastic transport regime, it is demonstrated that the relative change in the current (spin-torque) for F-S-F systems equals the relative change in the current (spin-torque) for F-N-F systems upon changing the relative magnetization direction of the two ferromagnets. This differs from the results in the inelastic transport regime where spin-accumulation suppresses the superconducting gap and dramatically changes the magnetoresistance [S. Takahashi, H. Imamura, and S. Maekawa, Phys. Rev. Lett. 82, 3911 (1999)]. The experimental relevance of the elastic and inelastic transport regimes, respectively, as well as the reasons for the change in the transport properties are discussed.Comment: 7 page