Effect of Beam tunnels on Resonant Frequency of Cylindrical Reentrant Cavity

Analytical formulations for the resonant frequency of a reentrant cavity for klystron are available in the literature only for such cavities having a single beam-tunnel. An improved analytical formulation has been proposed in this paper for the calculation of cavity gap-capacitance of reentrant cavities having single and multiple beam-tunnels and its effects on the resonant frequency are studied. The results obtained through analysis have been validated against those obtained from the 3D electromagnetic field simulations and measurements. The proposed analytical formulation provides good estimation of resonant frequency of cavity with single and multiple beam-tunnels

Adaptation of Rhizobium leguminosarum to pea, alfalfa and sugar beet rhizospheres investigated by comparative transcriptomics

BACKGROUND: The rhizosphere is the microbe-rich zone around plant roots and is a key determinant of the biosphere's productivity. Comparative transcriptomics was used to investigate general and plant-specific adaptations during rhizosphere colonization. Rhizobium leguminosarum biovar viciae was grown in the rhizospheres of pea (its legume nodulation host), alfalfa (a non-host legume) and sugar beet (non-legume). Gene expression data were compared to metabolic and transportome maps to understand adaptation to the rhizosphere. RESULTS: Carbon metabolism was dominated by organic acids, with a strong bias towards aromatic amino acids, C1 and C2 compounds. This was confirmed by induction of the glyoxylate cycle required for C2 metabolism and gluconeogenesis in all rhizospheres. Gluconeogenesis is repressed in R. leguminosarum by sugars, suggesting that although numerous sugar and putative complex carbohydrate transport systems are induced in the rhizosphere, they are less important carbon sources than organic acids. A common core of rhizosphere-induced genes was identified, of which 66% are of unknown function. Many genes were induced in the rhizosphere of the legumes, but not sugar beet, and several were plant specific. The plasmid pRL8 can be considered pea rhizosphere specific, enabling adaptation of R. leguminosarum to its host. Mutation of many of the up-regulated genes reduced competitiveness for pea rhizosphere colonization, while two genes specifically up-regulated in the pea rhizosphere reduced colonization of the pea but not alfalfa rhizosphere. CONCLUSIONS: Comparative transcriptome analysis has enabled differentiation between factors conserved across plants for rhizosphere colonization as well as identification of exquisite specific adaptation to host plants

The architecture and ppGpp-dependent expression of the primary transcriptome of Salmonella Typhimurium during invasion gene expression

<p>Abstract</p> <p>Background</p> <p>Invasion of intestinal epithelial cells by <it>Salmonella enterica </it>serovar Typhimurium (<it>S</it>. Typhimurium) requires expression of the extracellular virulence gene expression programme (ST^EX), activation of which is dependent on the signalling molecule guanosine tetraphosphate (ppGpp). Recently, next-generation transcriptomics (RNA-seq) has revealed the unexpected complexity of bacterial transcriptomes and in this report we use differential RNA sequencing (dRNA-seq) to define the high-resolution transcriptomic architecture of wild-type <it>S</it>. Typhimurium and a ppGpp null strain under growth conditions which model ST^EX. In doing so we show that ppGpp plays a much wider role in regulating the <it>S</it>. Typhimurium ST^EXprimary transcriptome than previously recognised.</p> <p>Results</p> <p>Here we report the precise mapping of transcriptional start sites (TSSs) for 78% of the <it>S</it>. Typhimurium open reading frames (ORFs). The TSS mapping enabled a genome-wide promoter analysis resulting in the prediction of 169 alternative sigma factor binding sites, and the prediction of the structure of 625 operons. We also report the discovery of 55 new candidate small RNAs (sRNAs) and 302 candidate antisense RNAs (asRNAs). We discovered 32 ppGpp-dependent alternative TSSs and determined the extent and level of ppGpp-dependent coding and non-coding transcription. We found that 34% and 20% of coding and non-coding RNA transcription respectively was ppGpp-dependent under these growth conditions, adding a further dimension to the role of this remarkable small regulatory molecule in enabling rapid adaptation to the infective environment.</p> <p>Conclusions</p> <p>The transcriptional architecture of <it>S</it>. Typhimurium and finer definition of the key role ppGpp plays in regulating <it>Salmonella </it>coding and non-coding transcription should promote the understanding of gene regulation in this important food borne pathogen and act as a resource for future research.</p

Jumlah Bakteri Staphylococcus Aureus Dan Skor California Mastitis Test (CMT) Pada Susu Kambing Peranakan Etawa Akibat Dipping Ekstrak Daun Babadotan (Ageratum Conyzoides L.)

The aim of this research is to determine the effect of teat dipping of Ettawa crossbred goat using babadotan leaves (Ageratum conyzoides Linn.) extract on the number of Staphylococcus aureusin milk. The udder inflammation degree also was determined using California Mastitis Test (CMT). The treatments were post milking teat dipping using antiseptic solutions containing 1%, 3%, and 5% of babadotan leaves extract (T1, T2 and T3, respectively). Milk samples were collected at before treatment (H0) and on the day 3, 6 and 9 day of the treatments (H3, H6 and H9, respectively). Commercially antiseptic povidone iodine was used as positive control (K+). Experimental research design was completely randomized design (CRD) split plot types, with the different extract concentration as the main plot and the day of treatment as subplot. CMT scores was analyzed using Kruskal-Wallis test. The results showed that babadotan leaves extract 5% had the same effectiveness (p&gt;0,05) with povidone iodine to reduce the number of Staphylococcus aureusin milk. All extract concentrations (1%, 3% and 5%) had the same effectiveness (H&gt;c0,05(3)) to decrease the CMT scores by postmilking teat dip treatments for 9 days

Gadolinium silicide (Gd5Si4) nanoparticles for tuneable broad band microwave absorption

Soft magnetic Gd5Si4 nanoparticles exhibit excellent microwave absorption in the Ku-band (12.4-18 GHz) when dispersed in poly (dimethyl siloxane), PDMS. The minimum experimentally recorded reflection loss (RL) of Gd5Si4-PDMS nanocomposite is −69 dB, with a large bandwidth for a single 6 mm-thick layer. The bandwidth can be further extended by using a novel design where 1 mm-thick layers of the nanocomposite are arranged into a modified pyramid-shaped absorber. Standard electromagnetic (EM) simulations confirm experimental results

Enhancement of microwave absorption bandwidth of polymer blend using ferromagnetic gadolinium silicide nanoparticles

Ferromagnetic gadolinium silicide (Gd5Si4) nanoparticles significantly enhance the microwave absorption bandwidth of a polymer blend (PVB-PEDOT:PSS). These materials are critically needed for various military and civilian applications such as X-band (8.2–12.4 GHz) and Ku-band (12.4–18 GHz) absorption. A single 1.2 mm thick layer of PVB-PEDOT:PSS-Gd5Si4 (PPGS) nanocomposite film shows the most promising bandwidth (8.2–18 GHz) with a minimum reflection loss of -14 dB. Mechanistically, dielectric loss (tan δe ≈2.4) and magnetic loss (tan δm ≈1.1) contributes more efficiently, and standard microwave simulation confirms the stored energy is predominant in PPGS nanocomposite which enhances the bandwidth

Nutritional and Metabolic Requirements for the Infection of HeLa Cells by Salmonella enterica Serovar Typhimurium

Salmonella is the causative agent of a spectrum of human and animal diseases ranging from gastroenteritis to typhoid fever. It is a food - and water - borne pathogen and infects via ingestion followed by invasion of intestinal epithelial cells and phagocytic cells. In this study we employed a mutational approach to define the nutrients and metabolic pathways required by Salmonella enterica serovar Typhimurium during infection of a human epithelial cell line (HeLa). We deleted the key glycolytic genes, pfkA and pfkB to show that S. Typhimurium utilizes glycolysis for replication within HeLa cells; however, glycolysis was not absolutely essential for intracellular replication. Using S. Typhimurium strains deleted for genes encoding components of the phosphotransferase system and glucose transport, we show that glucose is a major substrate required for the intracellular replication of S. Typhimurium in HeLa cells. We also deleted genes encoding enzymes involved in the utilization of gluconeogenic substrates and the glyoxylate shunt and show that neither of these pathways were required for intracellular replication of S. Typhimurium within HeLa cells

Sequential induction of three recombination directionality factors directs assembly of tripartite integrative and conjugative elements

Tripartite integrative and conjugative elements (ICE3) are a novel form of ICE that exist as three separate DNA regions integrated within the genomes of Mesorhizobium spp. Prior to conjugative transfer the three ICE3 regions of M. ciceri WSM1271 ICEMcSym1271 combine and excise to form a single circular element. This assembly requires three coordinated recombination events involving three site-specific recombinases IntS, IntG and IntM. Here, we demonstrate that three excisionases–or recombination directionality factors—RdfS, RdfG and RdfM are required for ICE3 excision. Transcriptome sequencing revealed that expression of ICE3 transfer and conjugation genes was induced by quorum sensing. Quorum sensing activated expression of rdfS, and in turn RdfS stimulated transcription of both rdfG and rdfM. Therefore, RdfS acts as a “master controller” of ICE3 assembly and excision. The dependence of all three excisive reactions on RdfS ensures that ICE3 excision occurs via a stepwise sequence of recombination events that avoids splitting the chromosome into a non-viable configuration. These discoveries expose a surprisingly simple control system guiding molecular assembly of these novel and complex mobile genetic elements and highlight the diverse and critical functions of excisionase proteins in control of horizontal gene transfer

Mesenchymal Stem Cell Responses to Bone-Mimetic Electrospun Matrices Composed of Polycaprolactone, Collagen I and Nanoparticulate Hydroxyapatite

The performance of biomaterials designed for bone repair depends, in part, on the ability of the material to support the adhesion and survival of mesenchymal stem cells (MSCs). In this study, a nanofibrous bone-mimicking scaffold was electrospun from a mixture of polycaprolactone (PCL), collagen I, and hydroxyapatite (HA) nanoparticles with a dry weight ratio of 50/30/20 respectively (PCL/col/HA). The cytocompatibility of this tri-component scaffold was compared with three other scaffold formulations: 100% PCL (PCL), 100% collagen I (col), and a bi-component scaffold containing 80% PCL/20% HA (PCL/HA). Scanning electron microscopy, fluorescent live cell imaging, and MTS assays showed that MSCs adhered to the PCL, PCL/HA and PCL/col/HA scaffolds, however more rapid cell spreading and significantly greater cell proliferation was observed for MSCs on the tri-component bone-mimetic scaffolds. In contrast, the col scaffolds did not support cell spreading or survival, possibly due to the low tensile modulus of this material. PCL/col/HA scaffolds adsorbed a substantially greater quantity of the adhesive proteins, fibronectin and vitronectin, than PCL or PCL/HA following in vitro exposure to serum, or placement into rat tibiae, which may have contributed to the favorable cell responses to the tri-component substrates. In addition, cells seeded onto PCL/col/HA scaffolds showed markedly increased levels of phosphorylated FAK, a marker of integrin activation and a signaling molecule known to be important for directing cell survival and osteoblastic differentiation. Collectively these results suggest that electrospun bone-mimetic matrices serve as promising degradable substrates for bone regenerative applications

Group delay engineering using cascaded all pass filters for wideband chirp waveform generation

In this paper a second order all pass filter (APF) is designed and analyzed for its potential application for wideband chirp waveform generation. The group delay of a single stage APF varies with frequency within a narrow band and remains flat elsewhere. Furthermore, it has been found that the component values have a great role in the group delay response of the APF. A two stage cascaded second order APF is adopted to enhance the group delay over a wider band. Genetic algorithm is used to optimize the design parameters of the individual APF stages to obtain a smooth and monotonically increasing group delay response while ensuring good input return loss characteristics. This design approach can be used for generating wideband chirp waveforms that have potential applications in radar, sonar and imaging, delivering improved range resolution.Accepted versio