3,190 research outputs found

    Unmet Need: How the gap is Filled

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    \u3ci\u3eLevisunguis subaequalis\u3c/i\u3e n. g., n. sp., a Tongue Worm (Pentastomida: Porocephalida: Sebekidae) Infecting Softshell Turtles, \u3ci\u3eApalone\u3c/i\u3e spp. (Testudines: Trionychidae), in the Southeastern United States

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    A new tongue worm (Pentastomida) belonging to the Sebekidae Sambon, 1922 (Porocephaloidea Sambon, 1922) is described based on exemplars collected from softshell terrapins Apalone spinifera aspera (Agassiz) and Apalone ferox (Schneider) in the southeastern United States; a new genus is erected to accommodate the new species. The new species belongs in the Sebekidae because adults possess four simple hooks arranged in a trapezoid pattern on the ventral surface of the cephalothorax, a mouth opening between the anterior and posterior pairs of hooks, a terminal anus, an elongated uterus with preanal uterine pore, and a Y-shaped seminal vesicle. Nymphs possess geminate hooks, and the new species has an aquatic life cycle in which nymphs become encapsulated in the body cavity of a freshwater fish and mature in the lungs of a terrapin. The new genus is distinct from other genera in the Sebekidae primarily by differences in hook morphology and the fact that representatives use a terrapin as a definitive host. Nymphs infecting fish and presumed to be the new species matured as postlarval juveniles conspecific with the new species when they were fed to the eastern mud turtle, Kinosternon subrubrum (Lacépède). Nymphs of the new species are anatomically similar to but larger than nymphs of Sebekia mississippiensis Overstreet, Self & Vliet, 1985 found in the mesentery of fishes captured in Florida, USA. Adults of the new species differ from those of S. mississippiensis based on hook features, chloride cell pore pattern on annuli, body size, and use of a turtle rather than crocodilian definitive host. The new species is the third North American member of the Sebekidae

    Ponderomotive effects in multiphoton pair production

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    The Dirac-Heisenberg-Wigner formalism is employed to investigate electron-positron pair production in cylindrically symmetric but otherwise spatially inhomogeneous, oscillating electric fields. The oscillation frequencies are hereby tuned to obtain multiphoton pair production in the nonperturbative threshold regime. An effective mass as well as a trajectory-based semi-classical analysis are introduced in order to interpret the numerical results for the distribution functions as well as for the particle yields and spectra. The results, including the asymptotic particle spectra, display clear signatures of ponderomotive forces.Comment: 9 pages, 3 Tables, 3 Figure

    Experimental implementation of a quantum optical state comparison amplifier

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    We present an experimental demonstration of a practical nondeterministic quantum optical amplification scheme that employs two mature technologies, state comparison and photon subtraction, to achieve amplification of known sets of coherent states with high fidelity. The amplifier uses coherent states as a resource rather than single photons, which allows for a relatively simple light source, such as a diode laser, providing an increased rate of amplification. The amplifier is not restricted to low amplitude states. With respect to the two key parameters, fidelity and the amplified state production rate, we demonstrate significant improvements over previous experimental implementations, without the requirement of complex photonic components. Such a system may form the basis of trusted quantum repeaters in nonentanglement-based quantum communications systems with known phase alphabets, such as quantum key distribution or quantum digital signatures

    Mechanisms of Acute Eosinophil Mobilization from the Bone Marrow Stimulated by Interleukin 5: The Role of Specific Adhesion Molecules and Phosphatidylinositol 3-Kinase

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    Mobilization of bone marrow eosinophils is a critical early step in their trafficking to the lung during allergic inflammatory reactions. We have shown previously that the cytokine interleukin (IL)-5, generated during an allergic inflammatory reaction in the guinea pig, acts systemically to mobilize eosinophils from the bone marrow. Here, we have investigated the mechanisms underlying this release process. Examination by light and electron microscopy revealed the rapid migration of eosinophils from the hematopoietic compartment and across the bone marrow sinus endothelium in response to IL-5. Using an in situ perfusion system of the guinea pig hind limb, we showed that IL-5 stimulated a dose-dependent selective release of eosinophils from the bone marrow. Eosinophils released from the bone marrow in response to IL-5 expressed increased levels of β2 integrin and a decrease in L-selectin, but no change in α4 integrin levels. A β2 integrin–blocking antibody markedly inhibited the mobilization of eosinophils from the bone marrow stimulated by IL-5. In contrast, an α4 integrin blocking antibody increased the rate of eosinophil mobilization induced by IL-5. In vitro we demonstrated that IL-5 stimulates the selective chemokinesis of bone marrow eosinophils, a process markedly inhibited by two structurally distinct inhibitors of phosphatidylinositol 3-kinase, wortmannin and LY294002. Wortmannin was also shown to block eosinophil release induced by IL-5 in the perfused bone marrow system. The parallel observations on the bone marrow eosinophil release process and responses in isolated eosinophils in vitro suggest that eosinophil chemokinesis is the driving force for release in vivo and that this release process is regulated by α4 and β2 integrins acting in opposite directions

    Loose Groups of Galaxies in the Las Campanas Redshift Survey

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    A ``friends-of-friends'' percolation algorithm has been used to extract a catalogue of dn/n = 80 density enhancements (groups) from the six slices of the Las Campanas Redshift Survey (LCRS). The full catalogue contains 1495 groups and includes 35% of the LCRS galaxy sample. A clean sample of 394 groups has been derived by culling groups from the full sample which either are too close to a slice edge, have a crossing time greater than a Hubble time, have a corrected velocity dispersion of zero, or contain a 55-arcsec ``orphan'' (a galaxy with a mock redshift which was excluded from the original LCRS redshift catalogue due to its proximity to another galaxy -- i.e., within 55 arcsec). Median properties derived from the clean sample include: line-of-sight velocity dispersion sigma_los = 164km/s, crossing time t_cr = 0.10/H_0, harmonic radius R_h = 0.58/h Mpc, pairwise separation R_p = 0.64/h Mpc, virial mass M_vir = (1.90x10^13)/h M_sun, total group R-band luminosity L_tot = (1.30x10^11)/h^2 L_sun, and R-band mass-to-light ratio M/L = 171h M_sun/L_sun; the median number of observed members in a group is 3.Comment: 32 pages of text, 27 figures, 7 tables. Figures 1, 4, 6, 7, and 8 are in gif format. Tables 1 and 3 are in plain ASCII format (in paper source) and are also available at http://www-sdss.fnal.gov:8000/~dtucker/LCLG . Accepted for publication in the September 2000 issue of ApJ

    Variation Analysis of Three Dimensional non-rigid Assemblies

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    Variation analysis methods are, currently, more widely used during new product development to greatly reduce downstream rework and/or design changes. This is significantly important when considering large, built up sheet or thin plate flexible" assemblies as those currently used in automotive or aerospace industries. Whereas methods to take flexibility into account can be found in literature, there are few addressing detailed process for three-dimensional assembly of industrial complexity. This paper presents a streamlined procedure for variation analysis of a complex assembly that integrates Datum Flow Chain analysis, a commercial three-dimensional variation analysis and FEA. The procedure is applied to a realistic industry case, a commercial airplane's wing-box assembly to determine the effect of part variation and flexibility on the assembly's variation. The case study shows that a structural enclosure such as the wing-box assembly is robust against pull-up forces applied during assembly operations.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87278/4/Saitou64.pd

    Accurate EELS background subtraction – an adaptable method in MATLAB

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    Electron energy-loss spectroscopy (EELS) is a technique that can give useful information on elemental composition and bonding environments. However in practice, the complexity of the background contributions, which can arise from multiple sources, can hamper the interpretation of the spectra. As a result, background removal is both an essential and difficult part of EELS analysis, especially during quantification of elemental composition. Typically, a power law is used to fit the background but this is often not suitable for many spectra such as in the low-loss region (< 50 eV) and when there are overlapping EELS edges. In this article, we present a series of scripts written in MATLAB v. R2019b that aims to provide statistical information on the model used to fit the background, allowing the user to determine the accuracy of background subtraction. The scripts were written for background subtraction of vibrational EELS in the ultralow-loss region near the zero-loss peak but can also be applied to other kinds of EEL spectra. The scripts can use a range of models for fitting, provided by the Curve Fitting Toolbox of MATLAB, and the user is able to precisely define the window for fitting as well as for edge integration. We demonstrate the advantages of using these scripts by comparing their background subtraction of example spectra to the most commonly used software, Gatan Microscopy Suite 3. The example spectra include those containing multiple scattering, multiple overlapping peaks, as well as vibrational EELS. Additionally, a comprehensive guide to using the scripts has been included in the Supplementary Information

    Pneumococcal Colonisation Rates in Patients Admitted to a UK Hospital with Lower Respiratory Tract Infection - a prospective case-control study

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    BACKGROUND Current diagnostic tests are ineffective at identifying the aetiological pathogen in hospitalised adults with lower respiratory tract infection (LRTI). The association of pneumococcal colonisation with disease has been suggested as a means to increase diagnostic precision. We compared pneumococcal colonisation rate and density of nasal pneumococcal colonisation by a) classical culture and b) quantitative real time lytA Polymerase Chain Reaction (qPCR) in patients admitted to hospital in the UK with LRTI compared to control patients. METHODS 826 patients were screened for inclusion in this prospective case-control study. 38 patients were recruited, 19 with confirmed LRTI and 19 controls with another diagnosis. Nasal wash (NW) was collected at the time of recruitment. RESULTS Pneumococcal colonisation was detected in 1 LRTI patient and 3 controls (p=0.6) by classical culture. Using qPCR pneumococcal colonisation was detected in 10 LRTI patients and 8 controls (p=0.5). Antibiotic usage prior to sampling was significantly higher in the LRTI than control group 19 v. 3 (p8000 copies/ml on qPCR pneumococcal colonisation was found in 3 LRTI patients and 4 controls (p > 0.05). CONCLUSIONS We conclude that neither prevalence nor density of nasal pneumococcal colonisation (by culture and qPCR) can be used as a method of microbiological diagnosis in hospitalised adults with LRTI in the UK. A community based study recruiting patients prior to antibiotic therapy may be a useful future step

    Real-Time Feedback of Air Quality in Children’s Bedrooms Reduces Exposure to Secondhand Smoke

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    Introduction:Secondhand smoke (SHS) exposure creates health risks for nonsmokers and is especially detrimental to children. This study evaluated whether immediate feedback in response to poor indoor air quality in children’s bedrooms can reduce the potential for SHS exposure, as measured by adherence to a World Health Organization (WHO) indoor air standard.Methods:Homes that contained children and an adult who regularly smoked inside (n=298) had an air particle monitor installed in the child’s bedroom. These devices measured the concentration of particulate matter (PM2.5) for approximately three months and, for half of the participants, immediately provided aversive feedback in response to elevated PM2.5. Hierarchical linear models were fit to the data to assess whether the intervention increased the probability that: 1) a given day was below the WHO guideline for daily exposure, and 2) a household established and maintained a smoke-free home (SFH), operationalized as achieving 30 consecutive days below the WHO guideline. The intervention’s impact was calculated as groupby- time effects.Results:The likelihood that a child’s bedroom met the WHO indoor air quality standard on a given day increased such that the baseline versus post-baseline odds ratio (OR) of maintaining indoor PM2.5 levels below the WHO guideline was 2.38 times larger for participants who received the intervention. Similarly, the baseline versus post-baseline OR associated with achieving an SFH was 3.49 times larger for participants in the intervention group.Conclusions:The real-time intervention successfully drove clinically meaningful changes in smoking behavior that mitigated indoor PM2.5 levels in children’s bedrooms and thereby reduced SHS exposure. These results demonstrate the effectiveness of targeting sensitive microenvironments by giving caregivers actionable information about children’s SHS risks. Future extensions should examine additional microenvironments and focus on identifying the potential for SHS exposure before it occurs
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