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Search Results: 1 - 10 of 401375 matches for " M. Lackner "
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Serotonin receptor modulators in the treatment of irritable bowel syndrome
Mohammad Fayyaz,Jeffrey M Lackner
Therapeutics and Clinical Risk Management , 2008,
Abstract: Mohammad Fayyaz, Jeffrey M LacknerDivision of Gastroenterology, Department of Medicine, University at Buffalo School of Medicine, SUNY, Buffalo, NY, USAAbstract: The aim of this article is to review the pathophysiology and clinical role of serotonin receptor modulators used in the treatment of irritable bowel syndrome. Serotonin is an important monoamine neurotransmitter that plays a key role in the initiation of peristaltic and secretory reflexes, and in modulation of visceral sensations. Several serotonin receptor subtypes have been characterized, of which 5HT3, 5HT4, and 5HT1b are the most important for GI function. 5HT4 agonists (eg, tegaserod) potentiate peristalsis initiated by 5HT1 receptor stimulation. 5HT4 agonists are therefore useful in constipation predominant form of IBS and in chronic constipation. 5HT3 antagonists (Alosetron and Cilansetron) prevent the activation of 5HT3 receptors on extrinsic afferent neurons and can decrease the visceral pain associated with IBS. These agents also retard small intestinal and colonic transit, and are therefore useful in diarrhea-predominant IBS. Tegaserod has been demonstrated in several randomized, placebo controlled trials to relieve global IBS symptoms as well as individual symptoms of abdominal discomfort, number of bowel movements and stool consistency. Several randomized, controlled trials have shown that alosetron relieves pain, improves bowel function, and provides global symptom improvement in women with diarrhea-predominant irritable bowel syndrome. However, ischemic colitis and severe complications of constipation have been major concerns leading to voluntary withdrawal of Alosetron from the market followed by remarketing with a comprehensive risk management program.Keywords: serotonin, irritable bowel syndrome, tegaserod
Parascedosporium and its relatives: phylogeny and ecological trends
M. Lackner,G.S. de Hoog
IMA Fungus , 2011,
Abstract: The genus Seedosporiurn and its relatives comprising microascalean anamorphs with slimy conidia were studied. Graphiurn and Paraseedosporiurn also belong to this complex, while teleomorphs are found in Pseudalleseheria, Petriella, Petriellopsis, and Lophotriehus. Species complexes were clearly resolved by rDNA ITS sequencing. Significantly different ecological trends were observed between resolved species aggregates. The Pseudalleseheria and Seedosporiurn pro/ifieans clades were the only lineages with a marked opportunistic potential to mammals, while Petriella species were associated primarily with soil enriched by, e.g.dung. A consistent association with bark beetles was observed in the Graphiurn clade. The ex-type strain of Rhinoe/adiurn /esnei, CBS 108.10 was incorrectly implicated by Vuillemin (1910) in a case of human mycetoma; its sequence was identical to that of the ex-type strain of Paraseedosporiurn teetonae, CBS 127.84.
Tribology of bio-inspired nanowrinkled films on ultrasoft substrates
Juergen M. Lackner,Wolfgang Waldhauser,Lukasz Major,Christian Teichert
Computational and Structural Biotechnology Journal , 2013, DOI: 10.5936/csbj.201303002
Abstract: Biomimetic design of new materials uses nature as antetype, learning from billions of years of evolution. This work emphasizes the mechanical and tribological properties of skin, combining both hardness and wear resistance of its surface (the stratum corneum) with high elasticity of the bulk (epidermis, dermis, hypodermis). The key for combination of such opposite properties is wrinkling, being consequence of intrinsic stresses in the bulk (soft tissue): Tribological contact to counterparts below the stress threshold for tissue trauma occurs on the thick hard stratum corneum layer pads, while tensile loads smooth out wrinkles in between these pads. Similar mechanism offers high tribological resistance to hard films on soft, flexible polymers, which is shown for diamond-like carbon (DLC) and titanium nitride thin films on ultrasoft polyurethane and harder polycarbonate substrates. The choice of these two compared substrate materials will show that ultra-soft substrate materials are decisive for the distinct tribological material. Hierarchical wrinkled structures of films on these substrates are due to high intrinsic compressive stress, which evolves during high energetic film growth. Incremental relaxation of these stresses occurs by compound deformation of film and elastic substrate surface, appearing in hierarchical nano-wrinkles. Nano-wrinkled topographies enable high elastic deformability of thin hard films, while overstressing results in zigzag film fracture along larger hierarchical wrinkle structures. Tribologically, these fracture mechanisms are highly important for ploughing and sliding of sharp and flat counterparts on hard-coated ultra-soft substrates like polyurethane. Concentration of polyurethane deformation under the applied normal loads occurs below these zigzag cracks. Unloading closes these cracks again. Even cyclic testing do not lead to film delamination and retain low friction behavior, if the adhesion to the substrate is high and the initial friction coefficient of the film against the sliding counterpart low, e.g. found for DLC.
Effect of hydrostatic pressure on the ambient pressure superconductor CePt_3Si
M. Nicklas,G. Sparn,R. Lackner,E. Bauer,F. Steglich
Physics , 2004, DOI: 10.1016/j.physb.2005.01.071
Abstract: We studied the evolution of superconductivity (sc) and antiferromagnetism (afm) in the heavy fermion compound CePt_3Si with hydrostatic pressure. We present a pressure-temperature phase diagram established by electrical transport measurements. Pressure shifts the superconducting transition temperature, T_c, to lower temperatures. Antiferromagnetism is suppressed at a critical pressure P_c=0.5 GPa.
Afroprinus cavicola gen. et sp. n. from the Afrotropical region with notes on cave-dwelling Saprininae (Coleoptera, Histeridae)
Tomá? Lackner
ZooKeys , 2013, DOI: 10.3897/zookeys.294.4800
Abstract: A new genus and species from Kenya, Afroprinus cavicola is herein described and illustrated and its systematic position is discussed. By the prosternal pre-apical foveae connected by marginal prosternal stria it resembles most of the Afrotropical species of the genus Chalcionellus Reichardt, 1932, or some species of the genus Pholioxenus Reichardt, 1932 from South Africa and Namibia. Afroprinus can be distinguished from Chalcionellus chiefly by the lack of pronotal depressions and a coarsely sculptured, non-metallic dorsum; from Afrotropical species of Pholioxenus it can be most easily distinguished by the asetose pronotal hypomeron. The new taxon was discovered in a cave, but lacks obvious troglophilic adaptations. Notes on other Saprininae taxa found in caves are given. An identification key to the genera of Afrotropical Saprininae is provided.
Pair breaking by nonmagnetic impurities in the noncentrosymmetric superconductor CePt3Si
M. Nicklas,F. Steglich,J. Knolle,I. Eremin,R. Lackner,E. Bauer
Physics , 2012, DOI: 10.1103/PhysRevB.81.180511
Abstract: We have studied the effect of Ge substitution and pressure on the heavy-fermion superconductor CePt3Si. Ge substitution on the Si site acts as negative chemical pressure leading to an increase in the unit-cell volume but also introduces chemical disorder. We carried out electrical resistivity and ac heat-capacity experiments under hydrostatic pressure on CePt3Si1-xGex (x=0, 0.06). Our experiments show that the suppression of superconductivity in CePt3Si1-xGex is mainly caused by the scattering potential, rather than volume expansion, introduced by the Ge dopants. The antiferromagnetic order is essentially not affected by the chemical disorder.
Building galaxies by accretion and in-situ star formation
C. N. Lackner,R. Cen,J. P. Ostriker,M. R. Joung
Physics , 2012, DOI: 10.1111/j.1365-2966.2012.21525.x
Abstract: We examine galaxy formation in a cosmological AMR simulation, which includes two high resolution boxes, one centered on a 3 \times 10^14 M\odot cluster, and one centered on a void. We examine the evolution of 611 massive (M\ast > 10^10M\odot) galaxies. We find that the fraction of the final stellar mass which is accreted from other galaxies is between 15 and 40% and increases with stellar mass. The accreted fraction does not depend strongly on environment at a given stellar mass, but the galaxies in groups and cluster environments are older and underwent mergers earlier than galaxies in lower density environments. On average, the accreted stars are ~2.5 Gyrs older, and ~0.15 dex more metal poor than the stars formed in-situ. Accreted stellar material typically lies on the outskirts of galaxies; the average half-light radius of the accreted stars is 2.6 times larger than that of the in-situ stars. This leads to radial gradients in age and metallicity for massive galaxies, in qualitative agreement with observations. Massive galaxies grow by mergers at a rate of approximately 2.6% per Gyr. These mergers have a median (mass-weighted) mass ratio less than 0.26 \pm 0.21, with an absolute lower limit of 0.20, for galaxies with M\ast ~ 10^12 M\odot. This suggests that major mergers do not dominate in the accretion history of massive galaxies. All of these results agree qualitatively with results from SPH simulations by Oser et al. (2010, 2012).
Efficient Direct Solar-to-Hydrogen Conversion by In Situ Interface Transformation of a Tandem Structure
Matthias M. May,Hans-Joachim Lewerenz,David Lackner,Frank Dimroth,Thomas Hannappel
Physics , 2015, DOI: 10.1038/ncomms9286
Abstract: Photosynthesis is nature's route to convert intermittent solar irradiation into storable energy, while its use for an industrial energy supply is impaired by low efficiency. Artificial photosynthesis provides a promising alternative for efficient robust carbon-neutral renewable energy generation. The approach of direct hydrogen generation by photoelectrochemical water splitting utilises customised tandem absorber structures to mimic the Z-scheme of natural photosynthesis. Here, a combined chemical surface transformation of a tandem structure and catalyst deposition at ambient temperature yields photocurrents approaching the theoretical limit of the absorber and results in a solar-to-hydrogen efficiency of 14%. The potentiostatically assisted photoelectrode efficiency is 17%. Present benchmarks for integrated systems are clearly exceeded. Details of the in situ interface transformation, the electronic improvement and chemical passivation are presented. The surface functionalisation procedure is widely applicable and can be precisely controlled, allowing further developments of high-efficiency robust hydrogen generators.
Impact of Endofungal Bacteria on Infection Biology, Food Safety, and Drug Development
Gerald Lackner,Christian Hertweck
PLOS Pathogens , 2011, DOI: 10.1371/journal.ppat.1002096
Analysis of the Induction and Wake Evolution of an Offshore Floating Wind Turbine
Thomas Sebastian,Matthew Lackner
Energies , 2012, DOI: 10.3390/en5040968
Abstract: The degrees-of-freedom associated with offshore floating wind turbines (OFWTs) result in a more dynamic flow field. The resulting aerodynamic loads may be significantly influenced by these motions via perturbations in the evolving wake. This is of great interest in terms of OFWT design, placement and simulation. This study presents free vortex wake method (FVM) simulations of the NREL 5-MW wind turbine of a variety of platforms, operating in a range of wind speeds synthesized platform motion time series. Motion-induced wake perturbations are observed to affect induction. Transitions between windmill and propeller states are also observed.
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