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Search Results: 1 - 10 of 44890 matches for " Michael Voelker "
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Aspirin plus Pseudoephedrine (Aspirin Complex) for the Treatment of Symptoms of Upper Respiratory Tract Infection  [PDF]
Michael Voelker, Ronald Eccles, Uwe Gessner
Open Journal of Respiratory Diseases (OJRD) , 2017, DOI: 10.4236/ojrd.2017.71004
Abstract: Upper respiratory tract infections or common colds are a multi-symptom disease which is usually symptomatically treated with fixed dose multi-active ingredient medicinal products which are commonly used as non-prescription and over the counter. However, the active ingredients combined require a particular and clinically sound justification. Analgesics and decongestant can be combined to treat simultaneously the prominent symptoms cold-related pain (e.g. headache, muscle aches and pains), fever, inflammationand nasal/sinus congestion. This overview provides a summary of the evidence supporting the combination of acetylsalicylic acid (aspirin) and pseudoephedrine available in the common cold product Aspirin? Complex.
Dynamical Behavior of the Dissipative Two-State System
Klaus Voelker
Physics , 1997, DOI: 10.1103/PhysRevB.58.1862
Abstract: We investigate the dynamical correlation function of a quantum-mechanical two-state system which is coupled to a bosonic heat bath, utilizing the equivalence between the spin-boson Hamiltonian and the 1/r^2 Ising model. The imaginary-time correlation function is calculated by Monte-Carlo simulations on the Ising system and then continued to real time by a Pade approximation. In the unbiased system, the transition from oscillatory to strongly damped behavior is found to occur at a coupling strength close to alpha = 1/2. The biased system favors coherent relaxation and displays a significantly larger crossover value alpha_c. We introduce the quasiparticle picture to describe the relevant behavior at intermediate time scales. Within this approximation, we map out phase diagrams for the unbiased and biased systems.
Dissipation-Driven Breakdown of Universality in Two-Dimensional Superconductors
Klaus Voelker
Physics , 1999,
Abstract: The influence of gapless dissipative degrees of freedom on the superconductor-insulator transition in two dimensions is investigated. We develop a series expansion for the free energy of a (2+1)-dimensional XY model coupled to a bosonic heat bath that can be approximately summed to all orders. The calculation explicitly conserves topological excitations. We derive the zero temperature phase diagram and the free energy critical exponent, and find a transition from universal to non-universal scaling behavior as the coupling to the dissipative environment is increased, implying the existence of a new universality class.
The Dopamine Receptor D4 Gene 7-Repeat Allele Interacts with Parenting Quality to Predict Effortful Control in Four-Year-Old Children
Brad E. Sheese,Mary K. Rothbart,Pascale M. Voelker,Michael I. Posner
Child Development Research , 2012, DOI: 10.1155/2012/863242
Abstract: The dopamine receptor D4 gene (DRD4) 7-repeat allele has been found to interact with environmental factors such as parenting in children and peer attitudes in adults to influence aspects of behavior such as risk taking. We previously found that in toddlers, lower-quality parenting in combination with the 7-repeat allele of the DRD4 gene was associated with greater parent-reported Sensation Seeking (SS), but was unrelated to Effortful Control (EC). We now report findings from a followup assessment with the same sample of children showing that parenting quality interacts with the presence of the 7-repeat allele to predict EC in 3- to 4-year-old children. The change in these patterns of results may reflect the increased role of the executive attention network in older children and adults. However, due to the small sample size ( ) and the novelty of the results, these findings should be treated with caution and considered preliminary until they are replicated in an independent sample. 1. Introduction Many studies suggest that the 7-repeat allele of the dopamine receptor D4 gene (DRD4) interacts with environmental factors to predict sensation seeking and externalizing behaviors in children and adults [1–5]. However, the mechanism through which DRD4 interacts with environmental factors remains unclear. One possibility is that DRD4 variations might influence these outcomes through the executive attention network that controls many forms of voluntary behavior [6]. In the current paper, we evaluate this hypothesis using data from a long-term longitudinal study of attention and temperament development in children. We review previously published results linking DRD4 and parenting to Sensation Seeking in toddlers and present new evidence linking DRD4 and parenting to Effortful Control (EC) in 3- to 4-year-old children. 1.1. DRD4 and Environmental Influences Many studies argue for the hypothesis that variations in DRD4 alter a child’s susceptibility to environmental factors [2, 3, 7]. A meta-analysis found that children with one or two copies of the DRD4 7-repeat allele may be more susceptible to both positive and negative environmental influences [8]. There is also evidence that the 7-repeat allele is undergoing positive selection in human evolution [9]. A possible explanation of positive selection is that increased susceptibility to environmental influences conferred by this variant might increase effectiveness of socialization, ultimately increasing the likelihood of reproduction [3]. There is further evidence that susceptibility to environmental influences
Developing Attention: Behavioral and Brain Mechanisms
Michael I. Posner,Mary K. Rothbart,Brad E. Sheese,Pascale Voelker
Advances in Neuroscience , 2014, DOI: 10.1155/2014/405094
Abstract: Brain networks underlying attention are present even during infancy and are critical for the developing ability of children to control their emotions and thoughts. For adults, individual differences in the efficiency of attentional networks have been related to neuromodulators and to genetic variations. We have examined the development of attentional networks and child temperament in a longitudinal study from infancy (7 months) to middle childhood (7 years). Early temperamental differences among infants, including smiling and laughter and vocal reactivity, are related to self-regulation abilities at 7 years. However, genetic variations related to adult executive attention, while present in childhood, are poor predictors of later control, in part because individual genetic variation may have many small effects and in part because their influence occurs in interaction with caregiver behavior and other environmental influences. While brain areas involved in attention are present during infancy, their connectivity changes and leads to improvement in control of behavior. It is also possible to influence control mechanisms through training later in life. The relation between maturation and learning may allow advances in our understanding of human brain development. 1. Introduction Few life changes are as dramatic as the development that occurs between infancy and elementary school, with locomotion, language, and voluntary control as the most obvious behavior changes. We also know that the brain changes in size, connectivity, and synaptic density during this period. What is least explored is exactly how these brain changes support behavioral change. Our research traces the development of attention networks that support the mechanisms of self-regulation, allowing children to control their emotions and behavior. In this paper, we first outline the connection between attention and self-regulation. In the next section, we examine measurement of individual differences in attention in adults. The heart of the paper summarizes the relation of early temperament (7 months) to later temperament and attention (age: 7 years). We show how changes in mechanisms of control over this period relate to genes and to the environment provided by the caregiver. Finally, we examine training studies that influence some of the same brain connections that change during development. During infancy, the caregiver provides much of the child’s regulation. Soothing by holding and rocking or by orienting of attention is a common practice for control of distress. Holding supports the child’s
Smoking reduces surfactant protein D and phospholipids in patients with and without chronic obstructive pulmonary disease
Jayaji M Moré, Dennis R Voelker, Lori J Silveira, Michael G Edwards, Edward D Chan, Russell P Bowler
BMC Pulmonary Medicine , 2010, DOI: 10.1186/1471-2466-10-53
Abstract: BAL SP-D and phospholipids were quantified and corrected for dilution in 110 subjects (65 healthy never smokers, 23 smokers with normal spirometry, and 22 smokers with COPD).BAL SP-D was highest in never smokers (mean 51.9 μg/mL ± 7.1 μg/mL standard error) compared to both smokers with normal spirometry (16.0 μg/mL ± 11.8 μg/mL) and subjects with COPD (19.1 μg/mL ± 12.9 μg/mL; P < 0.0001). Among smokers with COPD, BAL SP-D correlated significantly with FEV1% predicted (R = 0.43; P < 0.05); however, the strongest predictor of BAL SP-D was smoking status. BAL SP-D levels were lowest in current smokers (12.8 μg/mL ± 11.0 μg/mL), intermediate in former smokers (25.2 μg/mL ± 14.2 μg/mL; P < 0.008), and highest in never smokers. BAL phospholipids were also lowest in current smokers (6.5 nmol ± 1.5 nmol), intermediate in former smokers (13.1 nmol ± 2.1 nmol), and highest in never smokers (14.8 nmol ± 1.1 nmol; P < 0.0001).These data suggest that smokers, and especially current smokers, exhibit significantly reduced BAL SP-D and phospholipids compared to nonsmokers. Our findings may help better explain the mechanism that leads to the rapid progression of disease and increased incidence of infection in smokers.Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death in the United States [1], and worldwide, both COPD morbidity and mortality are expected to increase dramatically in the next ten years. Cigarette smoke is the major risk factor for COPD; however, not all smokers are diagnosed with COPD. One possible explanation for why some smokers do not develop clinically important COPD is the role that host factors play in limiting damage from smoking. One of the limitations in COPD research has been a lack of lung-specific biomarkers, particularly ones that could play a role in both pathogenesis and therapy. Surfactant protein D (SP-D) is a strong candidate for such a biomarker [2].SP-D is a large multimeric, calcium binding glycoprotein that is a mem
The Rediscovery of a Long Described Species Reveals Additional Complexity in Speciation Patterns of Poeciliid Fishes in Sulfide Springs
Maura Palacios, Lenin Arias-Rodriguez, Martin Plath, Constanze Eifert, Hannes Lerp, Anton Lamboj, Gary Voelker, Michael Tobler
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0071069
Abstract: The process of ecological speciation drives the evolution of locally adapted and reproductively isolated populations in response to divergent natural selection. In Southern Mexico, several lineages of the freshwater fish species of the genus Poecilia have independently colonized toxic, hydrogen sulfide-rich springs. Even though ecological speciation processes are increasingly well understood in this system, aligning the taxonomy of these fish with evolutionary processes has lagged behind. While some sulfide spring populations are classified as ecotypes of Poecilia mexicana, others, like P. sulphuraria, have been described as highly endemic species. Our study particularly focused on elucidating the taxonomy of the long described sulfide spring endemic, Poecilia thermalis Steindachner 1863, and investigates if similar evolutionary patterns of phenotypic trait divergence and reproductive isolation are present as observed in other sulfidic species of Poecilia. We applied a geometric morphometric approach to assess body shape similarity to other sulfidic and non-sulfidic fish of the genus Poecilia. We also conducted phylogenetic and population genetic analyses to establish the phylogenetic relationships of P. thermalis and used a population genetic approach to determine levels of gene flow among Poecilia from sulfidic and non-sulfidic sites. Our results indicate that P. thermalis' body shape has evolved in convergence with other sulfide spring populations in the genus. Phylogenetic analyses placed P. thermalis as most closely related to one population of P. sulphuraria, and population genetic analyses demonstrated that P. thermalis is genetically isolated from both P. mexicana ecotypes and P. sulphuraria. Based on these findings, we make taxonomic recommendations for P. thermalis. Overall, our study verifies the role of hydrogen sulfide as a main factor shaping convergent, phenotypic evolution and the emergence of reproductive isolation between Poecilia populations residing in adjacent sulfidic and non-sulfidic environments.
Spectral correlations in disordered mesoscopic metals and their relevance for persistent currents
Axel Voelker,Peter Kopietz
Physics , 1996, DOI: 10.1142/S0217984996001577
Abstract: We use the Lanczos method to calculate the variance of the number of energy levels in an energy window of width E below the Fermi energy for non-interacting disordered electrons on a thin three-dimensional ring threaded by an Aharonov-Bohm flux . We find that for small E the flux-dependent part of the variance is well described by a well-known Feynman diagram involving two Cooperons. However, this result cannot be extrapolated to energies E where the energy-dependence of the average density of states becomes significant. We discuss consequences for persistent currents.
Screening of persistent currents in mesoscopic metal rings
Axel Voelker,Peter Kopietz
Physics , 1996, DOI: 10.1007/s002570050324
Abstract: The effect of the Coulomb-interaction on persistent currents in disordered mesoscopic metal rings threaded by a magnetic flux $\phi$ is studied numerically. We use the simplest form of ``self-consistent'' Hartree theory, where the spatial variations of the self-consistent Hartree potential are ignored. In this approximation the self-consistent Hartree energies are simply obtained by diagonalizing the non-interacting system via the Lanczos method and then calculating the (disorder-dependent) particle number on the ring self-consistently. In the diffusive regime we find that the variance of the total particle number is strongly reduced, in agreement with the prediction of the random-phase approximation. On the other hand, the variance of the number of energy levels in a small interval below the Fermi energy is not affected by the Coulomb interaction.
Unconventional Superconductivity in MgCNi3
Klaus Voelker,Manfred Sigrist
Physics , 2002,
Abstract: A multiband superconductor with a conventional phonon mechanism can develop an unconventional state with a nontrivial order parameter phase relation between the individual bands. We propose that such a state can explain recent experimental results on MgCNi3, which are suggestive of both s-wave pairing symmetry and of unconventional superconductivity. We show that such a state gives rise to Andreev bound states, and to spontaneous currents, at surfaces and around impurities. We also investigate possible phase transitions between states with different order parameter symmetry.
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