495 research outputs found
Once again: Instanton method vs. WKB
A recent analytic test of the instanton method performed by comparing the
exact spectrum of the Lam potential (derived from representations
of a finite dimensional matrix expressed in terms of generators) with
the results of the tight--binding and instanton approximations as well as the
standard WKB approximation is commented upon. It is pointed out that in the
case of the Lam potential as well as others the WKB--related method
of matched asymptotic expansions yields the exact instanton result as a result
of boundary conditions imposed on wave functions which are matched in domains
of overlap.Comment: 10 pages, no figures. References list revised according to JHE
Leguminosenkörnerschrote und andere vegetabile Dünger im Ökologischen Gemüsebau
The potential of different plant based organic fertilisers (PBOF) to substitute animal based organic fertilisers (ABOF) in organic vegetable production were investigated in incubation, pot and field experiments. PBOFs have the potential to replace ABOFs. Particularly legume seed meals show fast net N-release even at low soil temperatures. Considerable differences in nitrate contents of vegetables can be found between the different fertilisers although fresh matter and N yields are nearly identical
D-Branes and their Absorptivity in Born-Infeld Theory
Standard methods of nonlinear dynamics are used to investigate the stability
of particles, branes and D-branes of abelian Born-Infeld theory. In particular
the equation of small fluctuations about the D-brane is derived and converted
into a modified Mathieu equation and - complementing earlier low-energy
investigations in the case of the dilaton-axion system - studied in the
high-energy domain. Explicit expressions are derived for the S-matrix and
absorption and reflection amplitudes of the scalar fluctuation in the presence
of the D-brane. The results confirm physical expectations and numerical studies
of others. With the derivation and use of the (hitherto practically unknown)
high energy expansion of the Floquet exponent our considerations also close a
gap in earlier treatments of the Mathieu equation.Comment: latex, 26 pages, 4 figures, one reference added, to appear in Nucl.
Phys.
Coherent States of the Deformed Heisenberg-Weyl Algebra in Noncommutative Space
In two-dimensional space a subtle point that for the case of both space-space
and momentum-momentum noncommuting, different from the case of only space-space
noncommuting, the deformed Heisenberg-Weyl algebra in noncommutative space is
not completely equivalent to the undeformed Heisenberg-Weyl algebra in
commutative space is clarified. It follows that there is no well defined
procedure to construct the deformed position-position coherent state or the
deformed momentum-momentum coherent state from the undeformed position-momentum
coherent state. Identifications of the deformed position-position and deformed
momentum-momentum coherent states with the lowest energy states of a cold
Rydberg atom in special conditions and a free particle, respectively, are
demonstrated.Comment: 10 pages, no figur
Quinpramine Ameliorates Rat Experimental Autoimmune Neuritis and Redistributes MHC Class II Molecules
Activation of inflammatory cells is central to the pathogenesis of autoimmune demyelinating diseases of the peripheral nervous system. The novel chimeric compound quinpramine—generated from imipramine and quinacrine—redistributes cholesterol rich membrane domains to intracellular compartments. We studied the immunological and clinical effects of quinpramine in myelin homogenate induced Lewis rat experimental autoimmune neuritis (EAN), a model system for acute human inflammatory neuropathies, such as the Guillain-Barré syndrome. EAN animals develop paresis of all limbs due to autoimmune inflammation of peripheral nerves. Quinpramine treatment ameliorated clinical disease severity of EAN and infiltration of macrophages into peripheral nerves. It reduced expression of MHC class II molecules on antigen presenting cells and antigen specific T cell proliferation both in vitro and in vivo. Quinpramine exerted its anti-proliferatory effect on antigen presenting cells, but not on responder T cells. Our data suggest that quinpramine represents a candidate pharmaceutical for inflammatory neuropathies
Pharmacogenetic Analysis of Voriconazole Treatment in Children
Voriconazole is among the first-line antifungal drugs to treat invasive fungal infections in children and known for its pronounced inter- and intraindividual pharmacokinetic variability. Polymorphisms in genes involved in the metabolism and transport of voriconazole are thought to influence serum concentrations and eventually the therapeutic outcome. To investigate the impact of these genetic variants and other covariates on voriconazole trough concentrations, we performed a retrospective data analysis, where we used medication data from 36 children suffering from invasive fungal infections treated with voriconazole. Data were extracted from clinical information systems with the new infrastructure SwissPKcdw, and linear mixed effects modelling was performed using R. Samples from 23 children were available for DNA extraction, from which 12 selected polymorphism were genotyped by real-time PCR. 192 (49.1%) of 391 trough serum concentrations measured were outside the recommended range. Voriconazole trough concentrations were influenced by polymorphisms within the metabolizing enzymes CYP2C19 and CYP3A4, and within the drug transporters ABCC2 and ABCG2, as well as by the co-medications ciprofloxacin, levetiracetam, and propranolol. In order to prescribe an optimal drug dosage, pre-emptive pharmacogenetic testing and careful consideration of co-medications in addition to therapeutic drug monitoring might improve voriconazole treatment outcome of children with invasive fungal infections.
Keywords: ABCC2; ABCG2; CYP2C19; CYP3A4; children; non-linear mixed effects modelling; pediatric pharmacology; pharmacogenetics; therapeutic drug monitoring; voriconazol
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Nodal variations and long-term changes in the main tides on the coasts of China
The long-term changes in the main tidal constituents (O1, K1, M2, N2, and S2) along the coasts of China and in adjacent seas are investigated based on 17 tide-gauge records covering the period 1954–2012. The observed 18.61 year nodal modulations of the diurnal constituents O1 and K1 are in agreement with the equilibrium tidal theory, except in the South China Sea. The observed modulations of the M2 and N2 amplitudes are smaller than theoretically predicted at the northern stations and larger at the southern stations. The discrepancies between the theoretically predicted nodal variations and the observations are discussed. The 8.85 year perigean cycle is identifiable in the N2 parameters at most stations, except those in the South China Sea. The radiational component of S2 contributes on average 16% of the observed S2 except in the Gulf of Tonkin, on the south coast, where it accounts for up to 65%. We confirmed the existence of nodal modulation in S2, which is stronger on the north coast. The semidiurnal tidal parameters show significant secular trends in the Bohai and Yellow Seas, on the north coast, and in the Taiwan Strait. The largest increase is found for M2 for which the amplitude increases by 4–7 mm/yr in the Yellow Sea. The potential causes for the linear trends in tidal constants are discussed
Angular Momentum of Supersymmetric Cold Rydberg Atoms
Semiunitary transformation is applied to discuss supersymmetrization of cold
Rydberg atoms. In the limit of vanishing kinetic energy the lowest angular
momentum of the supersymmetric cold Rydberg atom is . A possible
experimental verification is suggested.Comment: 11 pages, no figur
Management of biliary obstruction in patients with newly diagnosed alveolar echinococcosis: a Swiss retrospective cohort study
BACKGROUND AND STUDY AIMS: Alveolar echinococcosis, an orphan zoonosis affecting the liver, is of increasing concern worldwide. Most symptomatic cases present at an advanced and inoperable stage, sometimes with biliary obstruction prompting biliary tract interventions. These are, however, associated with a high risk of infectious complications. The aim of this retrospective study was to compare the effectiveness and safety of conservative and interventional treatment approaches in patients with newly diagnosed alveolar echinococcosis and biliary obstruction.
PATIENTS AND METHODS: Alveolar echinococcosis patients treated at two referral centres in Switzerland, presenting with hyperbilirubinaemia (total bilirubin >1.5 Upper Limit of Normal) at diagnosis were included, unless another underlying aetiology, i.e. common bile duct stones or decompensated cirrhosis, was identified. Patients were divided into two groups, according to whether they initially received a biliary tract intervention. The primary endpoint was normalisation of bilirubin levels within a 6-month period. Secondary endpoints included, among others, the occurrence of early and late biliary complications, the need for biliary tract interventions during follow-up and overall duration of hospital stays for treatment initiation and for biliary complications.
RESULTS: 28 patients were included in this study, of whom 17 received benzimidazole therapy alone and 11 additionally received a biliary tract intervention. Baseline characteristics did not differ between groups. All but one patient in each group achieved the primary endpoint (p=0.747). Biliary tract intervention was associated with faster laboratory improvement (t1/2 1.3 vs 3.0 weeks), but also with more frequent early biliary complications (7/11 vs 1/17, p=0.002) and longer initial hospital stay (18 days vs 7 days, p=0.007).
CONCLUSION: Biliary obstruction in patients with newly diagnosed alveolar echinococcosis can be treated effectively with benzimidazole therapy alone. Biliary tract intervention, on the other hand, is associated with a high complication rate and should probably be reserved for patients with insufficient response to benzimidazole therapy
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