1,358 research outputs found
Gas gain on single wire chambers filled with pure isobutane at low pressure
The gas gain of single-wire chambers filled with isobutane, with cell
cross-section 12x12 mm and wire diameters of 15, 25, 50 and 100 m, has
been measured at pressures ranging 12-92 Torr. Contrary to the experience at
atmospheric pressure, at very low pressures the gas gain on thick wires is
higher than that on thin wires at the same applied high voltage as was recently
shown. Bigger wire diameters should be used in wire chambers operating at very
low pressure if multiple scattering on wires is not an issue.Comment: 9 pages, 6 figure
Mice haploinsufficient for Map2k7, a gene involved in neurodevelopment and risk for schizophrenia, show impaired attention, a vigilance decrement deficit and unstable cognitive processing in an attentional task: impact of minocycline
Rationale:
Members of the c-Jun N-terminal kinase (JNK) family of mitogen-activated protein (MAP) kinases, and the upstream kinase MKK7, have all been strongly linked with synaptic plasticity and with the development of the neocortex. However, the impact of disruption of this pathway on cognitive function is unclear.
Objective:
In the current study, we test the hypothesis that reduced MKK7 expression is sufficient to cause cognitive impairment.
Methods:
Attentional function in mice haploinsufficient for Map2k7 (Map2k7+/â mice) was investigated using the five-choice serial reaction time task (5-CSRTT).
Results:
Once stable performance had been achieved, Map2k7+/â mice showed a distinctive attentional deficit, in the form of an increased number of missed responses, accompanied by a more pronounced decrement in performance over time and elevated intra-individual reaction time variability. When performance was reassessed after administration of minocyclineâa tetracycline antibiotic currently showing promise for the improvement of attentional deficits in patients with schizophreniaâsigns of improvement in attentional performance were detected.
Conclusions:
Overall, Map2k7 haploinsufficiency causes a distinctive pattern of cognitive impairment strongly suggestive of an inability to sustain attention, in accordance with those seen in psychiatric patients carrying out similar tasks. This may be important for understanding the mechanisms of cognitive dysfunction in clinical populations and highlights the possibility of treating some of these deficits with minocycline
Precision planar drift chambers and cradle for the TWIST muon decay spectrometer
To measure the muon decay parameters with high accuracy, we require an array
of precision drift detector layers whose relative position is known with very
high accuracy. This article describes the design, construction and performance
of these detectors in the TWIST (TRIUMF Weak Interaction Symmetry Test)
spectrometer.Comment: 44 pages, 16 Postscript figures, LaTeX2e, uses Elsevier class
elsart.cls, package graphicx, submitted to Nuclear Instruments & Methods in
Physics Researc
Study of a self quenching streamer mode in pure gases of DME and isobutane
A self quenching streamer (SQS), or limited streamer mode has been studied in
single wire chambers with cross-sections 12x12 mm and wire diameters 15, 25 and
50 microns. Chambers were filled with either pure dimethyl ether (DME) or
isobutane gases and irradiated with Gd-148 alpha and Fe-55 x-ray sources. Clear
transitions from a proportional to 100% SQS mode were observed on all three
diameter wires with both gases irradiated with alpha particles. Double SQS
discharges due to inclined tracks observed in DME gas allowed an estimation of
a streamer size along the wire of less than 1 mm. The second SQS discharge
appears less than 1 mm from the first within about 500 ns. Charge spectra
obtained with DME irradiated with Fe-55 x-rays might also be interpreted as a
transition to a SQS mode, although no direct evidence of that was seen in the
observed pulse shapes
The Immune Response to Herpes Simplex Virus Type 1 Infection in Susceptible Mice is a Major Cause of CNS Pathology Resulting in Fatal Encephalitis
This study was undertaken to investigate possible immune mechanisms in fatal HSV-1 encephalitis (HSE) after HSV-1 corneal inoculation. Susceptible 129S6 (129) but not resistant C57BL/6 (B6) mice developed intense focal inflammatory brainstem lesions of primarily F4/80+ macrophages and Gr-1+ neutrophils detectable by MRI as early as day 6 post infection (PI). Depletion of macrophages and neutrophils significantly enhanced survival of infected 129 mice. Immunodeficient B6 (IL-7R-/-Kitw41/w41) mice lacking adaptive cells (B6-E mice) transplanted with 129 bone marrow showed significantly accelerated fatal HSE compared to B6-E mice transplanted with B6 marrow or control non-transplanted B6-E mice. In contrast, there was no difference in ocular viral shedding in B6-E mice transplanted with 129 bone marrow or B6 bone marrow. Acyclovir treatment of 129 mice beginning day 4 PI (24 h after HSV-1 first reaches the brain stem) reduced nervous system viral titers to undetectable levels but did not alter brainstem inflammation or mortality. We conclude that fatal HSE in 129 mice results from widespread damage in the brainstem caused by destructive inflammatory responses initiated early in infection by massive infiltration of innate cells
Nasal Lipopolysaccharide Challenge and Cytokine Measurement Reflects Innate Mucosal Immune Responsiveness
<div><p>Background</p><p><b>P</b>ractical methods of monitoring innate immune mucosal responsiveness are lacking. Lipopolysaccharide (LPS) is a component of the cell wall of Gram negative bacteria and a potent activator of Toll-like receptor (TLR)-4. To measure LPS responsiveness of the nasal mucosa, we administered LPS as a nasal spray and quantified chemokine and cytokine levels in mucosal lining fluid (MLF).</p><p>Methods</p><p>We performed a 5-way cross-over, single blind, placebo-controlled study in 15 healthy non-atopic subjects (n = 14 <i>per protocol</i>). Doses of ultrapure LPS (1, 10, 30 or 100ÎŒg/100ÎŒl) or placebo were administered by a single nasal spray to each nostril. Using the recently developed method of nasosorption with synthetic adsorptive matrices (SAM), a series of samples were taken. A panel of seven cytokines/chemokines were measured by multiplex immunoassay in MLF. mRNA for intercellular cell adhesion molecule-1 (ICAM-1) was quantified from nasal epithelial curettage samples taken before and after challenge.</p><p>Results</p><p>Topical nasal LPS was well tolerated, causing no symptoms and no visible changes to the nasal mucosa. LPS induced dose-related increases in MLF levels of IL-1ÎČ, IL-6, CXCL8 (IL-8) and CCL3 (MIP-1α) (AUC at 0.5 to 10h, compared to placebo, p<0.05 at 30 and 100ÎŒg LPS). At 100ÎŒg LPS, IL-10, IFN-α and TNF-α were also increased (p<0.05). Dose-related changes in mucosal ICAM-1 mRNA were also seen after challenge, and neutrophils appeared to peak in MLF at 8h. However, 2 subjects with high baseline cytokine levels showed prominent cytokine and chemokine responses to relatively low LPS doses (10ÎŒg and 30ÎŒg LPS).</p><p>Conclusions</p><p>Topical nasal LPS causes dose-dependent increases in cytokines, chemokines, mRNA and cells. However, responsiveness can show unpredictable variations, possibly because baseline innate tone is affected by environmental factors. We believe that this new technique will have wide application in the study of the innate immune responses of the respiratory mucosa.</p><p>Key Messages</p><p>Ultrapure LPS was used as innate immune stimulus in a human nasal challenge model, with serial sampling of nasal mucosal lining fluid (MLF) by nasosorption using a synthetic absorptive matrix (SAM), and nasal curettage of mucosal cells. A dose response could be demonstrated in terms of levels of IL-1ÎČ, IL-6, CXCL8 and CCL3 in MLF, as well as ICAM-1 mRNA in nasal curettage specimens, and levels of neutrophils in nasal lavage. Depending on higher baseline levels of inflammation, there were occasional magnified innate inflammatory responses to LPS.</p><p>Trial Registration</p><p>Clinical Trials.gov <a href="https://clinicaltrials.gov/ct2/show/NCT02284074?term=nasal+lipopolysaccharide&rank=1" target="_blank">NCT02284074</a></p></div
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Visualisation of Origins, Destinations and Flows with OD Maps
We present a new technique for the visual exploration of origins (O) and destinations (D) arranged in geographic space. Previous attempts to map the flows between origins and destinations have suffered from problems of occlusion usually requiring some form of generalisation, such as aggregation or flow density estimation before they can be visualized. This can lead to loss of detail or the introduction of arbitrary artefacts in the visual representation. Here, we propose mapping OD vectors as cells rather than lines, comparable with the process of constructing OD matrices, but unlike the OD matrix, we preserve the spatial layout of all origin and destination locations by constructing a gridded twoâlevel spatial treemap. The result is a set of spatially ordered small multiples upon which any arbitrary geographic data may be projected. Using a hash grid spatial data structure, we explore the characteristics of the technique through a software prototype that allows interactive query and visualisation of 105â106 simulated and recorded OD vectors. The technique is illustrated using US county to county migration and commuting statistics
Genetic dissection of maturity using RFLPs.
Several genetic regions having major effects on maturity have been identified using RFLP analysis. One such region on chromosomes 8 is important across several diverse genotypes and ccounts for up to 50% of the variation for maturity in a cross involving an inbred line (N28) and a 20-backcross generation derivative (N28E). In addition to the chromsome 8 QTL for maturity, we have evidence using the backcross-derived line approach for regions controlling maturity on chromosomes 1, 2, 3, 5, 7, and 9. Chromosome 5 appears to be especially important in both magnitude of effect and across several genetic hackground. Maturity as measured by days to pollen shed or silking may be controlled by additive or nearly dominant gene action depending on the chromosome region. The marker-trait linkages were consistent across environnments based on A662 X B73 F3 per se and testcross evaluations from three locations in one year. UMC12 (chromosome 8) and UMC54 (chromosome 5) also marked important regions for maturity in these materials
The politics of the teaching of reading
Historically, political debates have broken out over how to teach reading in primary schools and infant classrooms. These debates and âreading warsâ have often resulted from public concerns and media reportage of a fall in reading standards. They also reflect the importance placed on learning to read by parents, teachers, employers, and politicians. Public and media-driven controversies over the teaching of reading have resulted in intense public and professional debates over which specific methods and materials to use with beginning readers and with children who have reading difficulties. Recently, such debates have led to a renewed emphasis on reading proficiency and âstandardizedâ approaches to teaching reading and engaging with literacy. The universal acceptance of the importance of learning to read has also led to vested interests in specific methods, reading programmes, and early literacy assessments amongst professional, business, commercial, and parental lobbying groups. This article traces these debates and the resulting growing support for a quantitative reductionist approach to early-reading programmes
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