232 research outputs found

    Medication beliefs, adherence, and outcomes in people with asthma: The importance of treatment beliefs in understanding inhaled corticosteroid nonadherence—a retrospective analysis of a real-world data set

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    BACKGROUND: Poor adherence to inhaled corticosteroids (ICSs) increases asthma morbidity and mortality and is influenced by patients’ treatment beliefs. This study maps patients’ beliefs about ICSs across 6 countries examining variations in beliefs, and their relationship with adherence and outcomes. OBJECTIVE: We sought to explore the relationship between patient treatment beliefs, and adherence and outcomes in asthma across 6 countries. METHODS: Patients 18 years or older with asthma, receiving ICS alone or in combination with a long-acting β2-agonist, were included from a point-in-time paper survey of patients with asthma in Europe and the United States. Clinical characteristics, such as adherence and asthma control, were collected by self- and physician-report. Patients completed the Beliefs about Medicines Questionnaire, adapted for ICSs. Relationships between patient treatment beliefs, adherence, and outcomes were examined using regression analyses. RESULTS: Data from 1312 patients were analyzed. Patients were from Germany (24%), the United States (21%), France (21%), Spain (16%), Italy (10%), and the United Kingdom (9%). Most had physician-reported mild-intermittent asthma (87%), and mean age was 40 ± 15.5 years. There was considerable variation in necessity beliefs between countries, with respondents in Italy having more doubts about treatment necessity and respondents in Spain showing higher concerns. Patients with doubts about ICS necessity and high concerns had lower self-reported (necessity: χ2(2) = 34.31, P < .001; concerns: χ2(2) = 20.98, P < .001) and physician-reported adherence (necessity: χ2(2) = 11.70, P = .003; concerns: χ2(2) = 34.45, P < .001). Patients with high necessity beliefs (F(2, 483) = 3.33; P = .037) and high concerns (F(2,483) = 23.46; P < .001) reported poorer control. Physician estimates of adherence did not correlate well with patient self-report (ρ = 0.178, P < .001). CONCLUSIONS: ICS necessity beliefs and concerns were associated with adherence and asthma control. This has implications for the design of adherence interventions

    Wavelength modulation spectroscopy of single quantum dots

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    We demonstrate that external cavity diode lasers with large mode-hop-free tuning ranges (up to 80 GHz) together with wavelength modulation spectroscopy can be used to study excitonic transitions in semiconductor nanostructures. Such transitions are characterized by homogeneous linewidths typically on the order of a few GHz. Wavelength modulation spectroscopy offers a high signal-to-noise method for the determination of resonance line shapes. We have used this technique to accurately measure dipole moments and dephasing rates of single semiconductor quantum dot eigenstates. These measurements are important for the use of quantum dots in semiconductor cavities and quantum logic gates, and for an improved understanding of the physics of exciton confinement. © 2002 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70029/2/APPLAB-80-11-1876-1.pd

    Single quantum dot states measured by optical modulation spectroscopy

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    Using optical modulation spectroscopy, we report the direct observation of absorption lines from excitons localized in GaAs single quantum dot potentials. The data provide a measurement of the linewidth, resonance energy, and oscillator strength of the transitions, and show that states which decay primarily by nonradiative processes can be directly probed using this technique. The experiments establish this technique for the characterization of single quantum dot transitions, thereby complementing luminescence studies. © 1999 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70527/2/APPLAB-75-19-2933-1.pd

    Manipulation of the Spin Memory of Electrons in n-GaAs

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    We report on the optical manipulation of the electron spin relaxation time in a GaAs based heterostructure. Experimental and theoretical study shows that the average electron spin relaxes through hyperfine interaction with the lattice nuclei, and that the rate can be controlled by the electron-electron interactions. This time has been changed from 300 ns down to 5 ns by variation of the laser frequency. This modification originates in the optically induced depletion of n-GaAs layer

    A fully automatic gridding method for cDNA microarray images

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    <p>Abstract</p> <p>Background</p> <p>Processing cDNA microarray images is a crucial step in gene expression analysis, since any errors in early stages affect subsequent steps, leading to possibly erroneous biological conclusions. When processing the underlying images, accurately separating the sub-grids and spots is extremely important for subsequent steps that include segmentation, quantification, normalization and clustering.</p> <p>Results</p> <p>We propose a parameterless and fully automatic approach that first detects the sub-grids given the entire microarray image, and then detects the locations of the spots in each sub-grid. The approach, first, detects and corrects rotations in the images by applying an affine transformation, followed by a polynomial-time optimal multi-level thresholding algorithm used to find the positions of the sub-grids in the image and the positions of the spots in each sub-grid. Additionally, a new validity index is proposed in order to find the correct number of sub-grids in the image, and the correct number of spots in each sub-grid. Moreover, a refinement procedure is used to correct possible misalignments and increase the accuracy of the method.</p> <p>Conclusions</p> <p>Extensive experiments on real-life microarray images and a comparison to other methods show that the proposed method performs these tasks fully automatically and with a very high degree of accuracy. Moreover, unlike previous methods, the proposed approach can be used in various type of microarray images with different resolutions and spot sizes and does not need any parameter to be adjusted.</p

    M3G: Maximum Margin Microarray Gridding

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    <p>Abstract</p> <p>Background</p> <p>Complementary DNA (cDNA) microarrays are a well established technology for studying gene expression. A microarray image is obtained by laser scanning a hybridized cDNA microarray, which consists of thousands of spots representing chains of cDNA sequences, arranged in a two-dimensional array. The separation of the spots into distinct cells is widely known as microarray image gridding.</p> <p>Methods</p> <p>In this paper we propose M<sup>3</sup>G, a novel method for automatic gridding of cDNA microarray images based on the maximization of the margin between the rows and the columns of the spots. Initially the microarray image rotation is estimated and then a pre-processing algorithm is applied for a rough spot detection. In order to diminish the effect of artefacts, only a subset of the detected spots is selected by matching the distribution of the spot sizes to the normal distribution. Then, a set of grid lines is placed on the image in order to separate each pair of consecutive rows and columns of the selected spots. The optimal positioning of the lines is determined by maximizing the margin between these rows and columns by using a maximum margin linear classifier, effectively facilitating the localization of the spots.</p> <p>Results</p> <p>The experimental evaluation was based on a reference set of microarray images containing more than two million spots in total. The results show that M<sup>3</sup>G outperforms state of the art methods, demonstrating robustness in the presence of noise and artefacts. More than 98% of the spots reside completely inside their respective grid cells, whereas the mean distance between the spot center and the grid cell center is 1.2 pixels.</p> <p>Conclusions</p> <p>The proposed method performs highly accurate gridding in the presence of noise and artefacts, while taking into account the input image rotation. Thus, it provides the potential of achieving perfect gridding for the vast majority of the spots.</p

    The sero-epidemiology of Neospora caninum in cattle in northern Tanzania

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    Neospora caninum is a protozoan intracellular parasite of animals with a global distribution. Dogs act as definitive hosts, with infection in cattle leading to reproductive losses. Neosporosis can be a major source of income loss for livestock keepers, but its impacts in sub-Saharan Africa are mostly unknown. This study aimed to estimate the seroprevalence and identify risk factors for N. caninum infection in cattle in northern Tanzania, and to link herd-level exposure to reproductive losses. Serum samples from 3,015 cattle were collected from 380 households in 20 villages between February and December 2016. Questionnaire data were collected from 360 of these households. Household coordinates were used to extract satellite derived environmental data from open-access sources. Sera were tested for the presence of N. caninum antibodies using an indirect ELISA. Risk factors for individual-level seropositivity were identified with logistic regression using Bayesian model averaging (BMA). The relationship between herd-level seroprevalence and abortion rates was assessed using negative binomial regression. The seroprevalence of N. caninum exposure after adjustment for diagnostic test performance was 21.5% [95% Credibility Interval (CrI) 17.9–25.4]. The most important predictors of seropositivity selected by BMA were age greater than 18 months [Odds ratio (OR) = 2.17, 95% CrI 1.45–3.26], the local cattle population density (OR = 0.69, 95% CrI 0.41–1.00), household use of restricted grazing (OR = 0.72, 95% CrI 0.25–1.16), and an increasing percentage cover of shrub or forest land in the environment surrounding a household (OR = 1.37, 1.00–2.14). There was a positive relationship between herd-level N. caninum seroprevalence and the reported within-herd abortion rate (Incidence Rate Ratio = 1.03, 95% CrI 1.00–1.06). Our findings suggest N. caninum is likely to be an important cause of abortion in cattle in Tanzania. Management practices, such as restricted grazing, are likely to reduce the risk of infection and suggest contamination of communal grazing areas may be important for transmission. Evidence for a relationship between livestock seropositivity and shrub and forest habitats raises questions about a potential role for wildlife in the epidemiology of N. caninum in Tanzania

    Expression Analysis of the Theileria parva Subtelomere-Encoded Variable Secreted Protein Gene Family

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    Background The intracellular protozoan parasite Theileria parva transforms bovine lymphocytes inducing uncontrolled proliferation. Proteins released from the parasite are assumed to contribute to phenotypic changes of the host cell and parasite persistence. With 85 members, genes encoding subtelomeric variable secreted proteins (SVSPs) form the largest gene family in T. parva. The majority of SVSPs contain predicted signal peptides, suggesting secretion into the host cell cytoplasm. Methodology/Principal Findings We analysed SVSP expression in T. parva-transformed cell lines established in vitro by infection of T or B lymphocytes with cloned T. parva parasites. Microarray and quantitative real-time PCR analysis revealed mRNA expression for a wide range of SVSP genes. The pattern of mRNA expression was largely defined by the parasite genotype and not by host background or cell type, and found to be relatively stable in vitro over a period of two months. Interestingly, immunofluorescence analysis carried out on cell lines established from a cloned parasite showed that expression of a single SVSP encoded by TP03_0882 is limited to only a small percentage of parasites. Epitope-tagged TP03_0882 expressed in mammalian cells was found to translocate into the nucleus, a process that could be attributed to two different nuclear localisation signals. Conclusions Our analysis reveals a complex pattern of Theileria SVSP mRNA expression, which depends on the parasite genotype. Whereas in cell lines established from a cloned parasite transcripts can be found corresponding to a wide range of SVSP genes, only a minority of parasites appear to express a particular SVSP protein. The fact that a number of SVSPs contain functional nuclear localisation signals suggests that proteins released from the parasite could contribute to phenotypic changes of the host cell. This initial characterisation will facilitate future studies on the regulation of SVSP gene expression and the potential biological role of these enigmatic proteins

    Improved GaN-based HEMT performance by nanocrystalline diamond capping

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    As a wide-bandgap semiconductor, gallium nitride (GaN) is an attractive material for next-generation power devices. To date, the capabilities of GaN-based high electron mobility transistors (HEMTs) have been limited by self-heating effects (drain current decreases due to phonon scattering-induced carrier velocity reductions at high drain fields). Despite awareness of this, attempts to mitigate thermal impairment have been limited due to the difficulties involved with placing high thermal conductivity materials close to heat sources in the device. Heat spreading schemes have involved growth of AIGaN/GaN on single crystal or CVD diamond, or capping of fullyprocessed HEMTs using nanocrystalline diamond (NCD). All approaches have suffered from reduced HEMT performance or limited substrate size. Recently, a "gate after diamond" approach has been successfully demonstrated to improve the thermal budget of the process by depositing NCD before the thermally sensitive Schottky gate and also to enable large-area diamond implementation
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