106 research outputs found

    Drift Chamber Utilizing Microstrip Readout for Testing a New Micro TPC Concept

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    A drift chamber type radiation detector is being used to examine design criteria for a new type of detector called a micro Time Projection Chamber (micro TPC) which is being proposed for use in high energy nuclear physics experiments. The main advantage of the micro TPC detector is its very low radiation thickness compared to its silicon counterpart. The micro TPC is a charged-particle detector which willbe optimized for good two track resolution which is needed inahigh track density environment. Such performance requires low electron diffusion and high resolution readout. The diffusion willbe reduced bylimiting the drift distance to 15 cm and by using a low diffusion gas such as dimethyl ether. High resolution willbe obtained by using a new readout technology called microstrips. Microstrips are a recent development using photolithography techniques that allow the creation of anodes a few microns in width with submicron precision. The main purpose of this test chamber is to demonstrate the feasibility of a micro TPC design using a low diffusion gas and to insure the sufficient signal remains after electron attenuation. The driftchamber design and the proposed testingprocedures are described

    Quasi-phase-matched generation of coherent extreme-ultraviolet light

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    Includes bibliographical references (page 54).High-harmonic generation is a well-known method of producing coherent extreme-ultraviolet (EUV) light, with photon energies up to about 0.5 keV. This is achieved by focusing a femtosecond laser into a gas, and high harmonics of the fundamental laser frequency are radiated in the forward direction. However, although this process can generate high-energy photons, efficient high-harmonic generation has been demonstrated only for photon energies of the order 50-100 eV. Ionization of the gas prevents the laser and the EUV light from propagating at the same speed, which severely limits the conversion efficiency. Here we report a technique to overcome this problem, and demonstrate quasi-phase-matched frequency conversion of laser light into EUV. Using a modulated hollow-core waveguide to periodically vary the intensity of the laser light driving the conversion, we efficiently generate EUV light even in the presence of substantial ionization. The use of a modulated fibre shifts the energy spectrum of the high-harmonic light to significantly higher photon energies than would otherwise be possible. We expect that this technique could form the basis of coherent EUV sources for advanced lithography and high-resolution imaging applications. In future work, it might also be possible to generate isolated attosecond pulses

    Role of macrophage sialoadhesin in host defense against the sialylated pathogen group B <em>Streptococcus</em>

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    ABSTRACT: Several bacterial pathogens decorate their surfaces with sialic acid (Sia) residues within cell wall components or capsular exopolysaccharides. Sialic acid expression can promote bacterial virulence by blocking complement activation or by engagement of inhibitory sialic acid-binding immunoglobulin-like lectins (Siglecs) on host leukocytes. Expressed at high levels on splenic and lymph node macrophages, sialoadhesin (Sn) is a unique Siglec with an elongated structure that lacks intracellular signaling motifs. Sialoadhesin allows macrophage to engage certain sialylated pathogens and stimulate inflammatory responses, but the in vivo significance of sialoadhesin in infection has not been shown. We demonstrate that macrophages phagocytose the sialylated pathogen group B Streptococcus (GBS) and increase bactericidal activity via sialoadhesin-sialic-acid-mediated recognition. Sialoadhesin expression on marginal zone metallophillic macrophages in the spleen trapped circulating GBS and restricted the spread of the GBS to distant organs, reducing mortality. Specific IgM antibody responses to GBS challenge were also impaired in sialoadhesin-deficient mice. Thus, sialoadhesin represents a key bridge to orchestrate innate and adaptive immune defenses against invasive sialylated bacterial pathogens. KEY MESSAGE: Sialoadhesin is critical for macrophages to phagocytose and clear GBS. Increased GBS organ dissemination in the sialoadhesin-deficient mice. Reduced anti-GBS IgM production in the sialoadhesin-deficient mice. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00109-014-1157-y) contains supplementary material, which is available to authorized users

    Translating healthcare innovation from academia to industry

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    Innovation lies at the heart of academia, and universities generate high-quality, intellectual property on a large scale. However, commercial translation of this intellectual property has traditionally been poor, particularly in the critical healthcare sector. It is critical that this situation is addressed to ensure that innovation from research institutes can fulfil its potential and progress to have a genuine impact on the outside world. In this article, we consider the nature of healthcare innovation in academia and ways in which commercial translation of intellectual property can be successfully realised. This is first analysed from an academic perspective, with a particular focus on how academic motivations and work practices can shape successful translation. We then switch perspective to examine the same process from an industry perspective, looking at the characteristics and expectations involved in the innovation life cycle. To place these analyses in context, we present a case study examining a project being undertaken to commercialise a novel surgical instrument, the intra-abdominal platform, from identification of clinical need, through the development life cycle, to commercialisation of the system. We reflect on the successes and challenges encountered during the intra-abdominal platform project, the broader lessons learned and in conclusion use these to emphasise how academia can adopt practices to better translate intellectual property in the future

    Immune modulation by group B Streptococcus influences host susceptibility to urinary tract infection by uropathogenic Escherichia coli

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    Urinary tract infection (UTI) is most often caused by uropathogenic Escherichia coli (UPEC). UPEC inoculation into the female urinary tract (UT) can occur through physical activities that expose the UT to an inherently polymicrobial periurethral, vaginal, or gastrointestinal flora. We report that a common urogenital inhabitant and opportunistic pathogen, group B Streptococcus (GBS), when present at the time of UPEC exposure, undergoes rapid UPEC-dependent exclusion from the murine urinary tract, yet it influences acute UPEC-host interactions and alters host susceptibility to persistent outcomes of bladder and kidney infection. GBS presence results in increased UPEC titers in the bladder lumen during acute infection and reduced inflammatory responses of murine macrophages to live UPEC or purified lipopolysaccharide (LPS), phenotypes that require GBS mimicry of host sialic acid residues. Taken together, these studies suggest that despite low titers, the presence of GBS at the time of polymicrobial UT exposure may be an overlooked risk factor for chronic pyelonephritis and recurrent UTI in susceptible groups, even if it is outcompeted and thus absent by the time of diagnosis

    Factors affecting the outcome of surgically treated non-iatrogenic traumatic cervical esophageal perforation: 28 years experience at a single center

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    <p>Abstract</p> <p>Background</p> <p>We reviewed our experience with non-iatrogenic traumatic cervical esophageal perforations, paying particular attention to factors affecting the outcome of such cases.</p> <p>Methods</p> <p>In total, 30 patients treated surgically between 1980 and 2008 for non-iatrogenic traumatic cervical esophageal perforation in our clinic were reviewed.</p> <p>Results</p> <p>There were 25 male and 5 female patients with a median age of 27.5 years. The type of injury was external trauma in 21 (70%) patients and endoluminal injury in the remaining 9 (30%) patients. The mechanism of injury was gunshot in 16 patients, stabbing in 4, falling in 1 (extraluminal injury), and foreign body in 9 (endoluminal injuries). The overall mortality rate was 16.6% (5/30). The mortality rate for extraluminal injuries was 19%, and for endoluminal injuries was 11.1%. Mortality in patients treated within 24 h of sustaining injury was substantially less than in those for whom diagnosis and treatment were delayed (12.5 and 21.4%, respectively). The mortality rate was 33.3% (3/9) for patients with tracheal injuries and 9.5% (2/21) for those without tracheal injuries.</p> <p>Conclusions</p> <p>A treatment delay greater than 24 h, the presence of tracheal injury, or extraluminal perforation significantly affected the outcome of surgically treated non iatrogenic traumatic cervical esophageal perforation.</p

    Moving toward and through trauma: participant experiences of multi-modal motion-assisted memory desensitization and reconsolidation (3MDR)

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    Introduction: Military members and Veterans are at risk of developing combat-related, treatment-resistant posttraumatic stress disorder (TR-PTSD) and moral injury (MI). Conventional trauma-focused therapies (TFTs) have shown limited success. Novel interventions including Multi-modal Motion-assisted Memory Desensitization and Reconsolidation therapy (3MDR) may prove successful in treating TR-PTSD.Objective: To qualitatively study the experiences of Canadian military members and Veterans with TR-PTSD who received the 3MDR intervention.Methods: This study explored qualitative data from a larger mixed-method waitlist control trial testing the efficacy of 3MDR in military members and veterans. Qualitative data were recorded and collected from 3MDR sessions, session debriefings and follow-up interviews up to 6 months post-intervention; the data were then thematically analyzed.Results: Three themes emerged from the data: (1) the participants' experiences with 3MDR; (2) perceived outcomes of 3MDR; and (3) keys to successful 3MDR treatment. Participants expressed that 3MDR provided an immersive environment, active engagement and empowerment. The role of the therapist as a coach and "fireteam partner" supports the participants' control over their therapy. The multi-modal nature of 3MDR, combining treadmill-walking toward self-selected trauma imagery with components of multiple conventional TFTs, was key to helping participants engage with and attribute new meaning to the memory of the traumatic experience.Discussion: Preliminary thematic analysis of participant experiences of 3MDR indicate that 3MDR has potential as an effective intervention for combat-related TR-PTSD, with significant functional, well-being and relational improvements reported post-intervention.Conclusion: Military members and Veterans are at risk of developing TR-PTSD, with worse outcomes than in civilians. Further research is needed into 3MDR and its use with other trauma-affected populations.Stress-related psychiatric disorders across the life spa

    Currency Unions

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    A currency union is when several independent sovereign nations share a common currency. This has been a recurring phenomenon in monetary history. In this article I study the theoretical foundations of such unions, and discuss some important currency unions in history, most notably the case of the US. Finally I contrast the design of the EMU with economic theories and historical experiences of currency unions

    The surface-anchored NanA protein promotes pneumococcal brain endothelial cell invasion

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    In humans, Streptococcus pneumoniae (SPN) is the leading cause of bacterial meningitis, a disease with high attributable mortality and frequent permanent neurological sequelae. The molecular mechanisms underlying the central nervous system tropism of SPN are incompletely understood, but include a primary interaction of the pathogen with the blood–brain barrier (BBB) endothelium. All SPN strains possess a gene encoding the surface-anchored sialidase (neuraminidase) NanA, which cleaves sialic acid on host cells and proteins. Here, we use an isogenic SPN NanA-deficient mutant and heterologous expression of the protein to show that NanA is both necessary and sufficient to promote SPN adherence to and invasion of human brain microvascular endothelial cells (hBMECs). NanA-mediated hBMEC invasion depends only partially on sialidase activity, whereas the N-terminal lectinlike domain of the protein plays a critical role. NanA promotes SPN–BBB interaction in a murine infection model, identifying the protein as proximal mediator of CNS entry by the pathogen
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