Self-healing fuse

Fast-acting current limiting device provides current overload protection for vulnerable circuit elements and then re-establishes conduction path within milliseconds. Fuse can also perform as fast-acting switch to clear transient circuit overloads. Fuse takes advantage of large increase in electrical resistivity that occurs when liquid metal vaporizes

Self-healing fuse development

The mercury-filled self-healing fuses developed for this program afford very good protection from circuit faults with rapid reclosure. Fuse performance and design parameters have been characterized. Life tests indicate a capability of 500 fuse operations. Fuse ratings are 150 v at 5, 15, 25 and 50 circuit A. A series of sample fuses using alumina and beryllia insulation have been furnished to NASA for circuit evaluation

Documentation of preventive screening interventions by general practitioners: a retrospective chart audit

<p>Abstract</p> <p>Background</p> <p>Screening and early diagnosis has been shown to reduce the morbidity and mortality associated with certain conditions such as cervical cancer. The role of general practitioners in promoting primary prevention of diseases is particularly important given that they have frequent contact with a large proportion of the population. This study assessed the extent to which general practitioners documented recommended preventive screening interventions among eligible patients.</p> <p>Methods</p> <p>We used a retrospective chart audit to assess patient visits to primary care clinics in Calgary, Canada from 2002-2004. We included fee for service physicians who practiced ≥ 2 days per week at their current location and excluded those whose primary practice was at walk-in clinics, community health centers, hospitals or emergency rooms. We included charts of patients who during the study period were age 35 years or older and had at least 2 visits to a clinic. We randomly selected and reviewed charts (N = 600) from 12 primary care clinics and abstracted information on 6 conditions recommended for preventive screening. Opportunities for preventive screening were determined based on recommendations of the Canadian Task Force on Preventive Health Care, the American College of Physicians, and the Canadian Cancer Society. Our main outcome measures included cancer screening (mammography and pap smears), immunization (influenza and pneumococcal), and risk factor assessment (cholesterol measurement and smoking cessation consultation).</p> <p>Results</p> <p>Patient visits to GP clinics present opportunities for preventive screening. However, we found that documentation of interventions was low, ranging from 40.3% (cholesterol measurement) to 0.9% (pneumococcal vaccination) within 1 year, and from 67.4% to 1.8% within the prior 3 years.</p> <p>Conclusions</p> <p>Documentation of preventive screening interventions by general practitioners was relatively low compared to the number of patients eligible for preventive screening. Some physicians opt to screen for PSA and DRE which is not recommended by the Canadian Task Force on Preventive HealthCare.</p

Australian clinicians and chemoprevention for women at high familial risk for breast cancer

<p>Abstract</p> <p>Objectives</p> <p>Effective chemoprevention strategies exist for women at high risk for breast cancer, yet uptake is low. Physician recommendation is an important determinant of uptake, but little is known about clinicians' attitudes to chemoprevention.</p> <p>Methods</p> <p>Focus groups were conducted with clinicians at five Family Cancer Centers in three Australian states. Discussions were recorded, transcribed and analyzed thematically.</p> <p>Results</p> <p>Twenty three clinicians, including genetic counselors, clinical geneticists, medical oncologists, breast surgeons and gynaecologic oncologists, participated in six focus groups in 2007. The identified barriers to the discussion of the use of tamoxifen and raloxifene for chemoprevention pertained to issues of evidence (evidence for efficacy not strong enough, side-effects outweigh benefits, oophorectomy superior for mutation carriers), practice (drugs not approved for chemoprevention by regulatory authorities and not government subsidized, chemoprevention not endorsed in national guidelines and not many women ask about it), and perception (clinicians not knowledgeable about chemoprevention and women thought to be opposed to hormonal treatments).</p> <p>Conclusion</p> <p>The study demonstrated limited enthusiasm for discussing breast cancer chemoprevention as a management option for women at high familial risk. Several options for increasing the likelihood of clinicians discussing chemoprevention were identified; maintaining up to date national guidelines on management of these women and education of clinicians about the drugs themselves, the legality of "off-label" prescribing, and the actual costs of chemopreventive medications.</p

Morphological analysis of the sheathed flagellum of Brucella melitensis

<p>Abstract</p> <p>Background</p> <p>It was recently shown that <it>B. melitensis </it>is flagellated. However, the flagellar structure remains poorly described.</p> <p>Findings</p> <p>We analyzed the structure of the polar sheathed flagellum of <it>B. melitensis </it>by TEM analysis and demonstrated that the Ryu staining is a good method to quickly visualize the flagellum by optical microscopy. The TEM analysis demonstrated that an extension of the outer membrane surrounds a filament ending by a club-like structure. The Δ<it>ftcR</it>, Δ<it>fliF</it>, Δ<it>flgE </it>and Δ<it>fliC </it>flagellar mutants still produce an empty sheath.</p> <p>Conclusions</p> <p>Our results demonstrate that the flagellum of <it>B. melitensis </it>has the characteristics of the sheathed flagella. Our results also suggest that the flagellar sheath production is not directly linked to the flagellar structure assembly and is not regulated by the FtcR master regulator.</p

Necrotrophism Is a Quorum-Sensing-Regulated Lifestyle in Bacillus thuringiensis

How pathogenic bacteria infect and kill their host is currently widely investigated. In comparison, the fate of pathogens after the death of their host receives less attention. We studied Bacillus thuringiensis (Bt) infection of an insect host, and show that NprR, a quorum sensor, is active after death of the insect and allows Bt to survive in the cadavers as vegetative cells. Transcriptomic analysis revealed that NprR regulates at least 41 genes, including many encoding degradative enzymes or proteins involved in the synthesis of a nonribosomal peptide named kurstakin. These degradative enzymes are essential in vitro to degrade several substrates and are specifically expressed after host death suggesting that Bt has an active necrotrophic lifestyle in the cadaver. We show that kurstakin is essential for Bt survival during necrotrophic development. It is required for swarming mobility and biofilm formation, presumably through a pore forming activity. A nprR deficient mutant does not develop necrotrophically and does not sporulate efficiently in the cadaver. We report that necrotrophism is a highly regulated mechanism essential for the Bt infectious cycle, contributing to spore spreading

Recommendations for the Generation, Quantification, Storage, and Handling of Peptides Used for Mass Spectrometry-Based Assays

BACKGROUND: For many years, basic and clinical researchers have taken advantage of the analytical sensitivity and specificity afforded by mass spectrometry in the measurement of proteins. Clinical laboratories are now beginning to deploy these work flows as well. For assays that use proteolysis to generate peptides for protein quantification and characterization, synthetic stable isotope-labeled internal standard peptides are of central importance. No general recommendations are currently available surrounding the use of peptides in protein mass spectrometric assays. CONTENT: The Clinical Proteomic Tumor Analysis Consortium of the National Cancer Institute has collaborated with clinical laboratorians, peptide manufacturers, metrologists, representatives of the pharmaceutical industry, and other professionals to develop a consensus set of recommendations for peptide procurement, characterization, storage, and handling, as well as approaches to the interpretation of the data generated by mass spectrometric protein assays. Additionally, the importance of carefully characterized reference materials-in particular, peptide standards for the improved concordance of amino acid analysis methods across the industry-is highlighted. The alignment of practices around the use of peptides and the transparency of sample preparation protocols should allow for the harmonization of peptide and protein quantification in research and clinical care

O Antigen Modulates Insect Vector Acquisition of the Bacterial Plant Pathogen Xylella fastidiosa

Hemipteran insect vectors transmit the majority of plant pathogens. Acquisition of pathogenic bacteria by these piercing/sucking insects requires intimate associations between the bacterial cells and insect surfaces. Lipopolysaccharide (LPS) is the predominant macromolecule displayed on the cell surface of Gram-negative bacteria and thus mediates bacterial interactions with the environment and potential hosts. We hypothesized that bacterial cell surface properties mediated by LPS would be important in modulating vector-pathogen interactions required for acquisition of the bacterial plant pathogen Xylella fastidiosa, the causative agent of Pierce's disease of grapevines. Utilizing a mutant that produces truncated O antigen (the terminal portion of the LPS molecule), we present results that link this LPS structural alteration to a significant decrease in the attachment of X. fastidiosa to blue-green sharpshooter foreguts. Scanning electron microscopy confirmed that this defect in initial attachment compromised subsequent biofilm formation within vector foreguts, thus impairing pathogen acquisition. We also establish a relationship between O antigen truncation and significant changes in the physiochemical properties of the cell, which in turn affect the dynamics of X. fastidiosa adhesion to the vector foregut. Lastly, we couple measurements of the physiochemical properties of the cell with hydrodynamic fluid shear rates to produce a Comsol model that predicts primary areas of bacterial colonization within blue-green sharpshooter foreguts, and we present experimental data that support the model. These results demonstrate that, in addition to reported protein adhesin-ligand interactions, O antigen is crucial for vector-pathogen interactions, specifically in the acquisition of this destructive agricultural pathogen