2,620 research outputs found
Transitive Packing: A Unifying Concept in Combinatorial Optimization
This paper attempts to give a better understanding of the facial structure of previously separately investigated polyhedra. It introduces the notion of transitive packing and the transitive packing polytope. Polytopes that turn out to be special cases of the transitive packing polytope are, among others, the node packing polytope, the acyclic subdigraph polytope, the bipartite subgraph polytope, the planar subgraph polytope, the clique partitioning polytope, the partition polytope, the transitive acyclic subdigraph polytope, the interval order polytope, and the relatively transitive subgraph polytope. We give cutting plane proofs for several rich classes of valid inequalities of the transitive packing polytope,in this way introducing generalized cycle, generalized clique, generalized antihole, generalized antiweb, and odd partition inequalities. These classes subsume several known classes of valid inequalities for several of the special cases and give also many new inequalities for several other special cases. For some of the classes we also prove a lower bound for their Gomory-Chvdtal rank. Finally, we relate the concept of transitive packing to generalized (set) packing and covering as well as to balanced and ideal matrices
Decoherence and Entropy Production in Relativistic Nuclear Collisions
Short thermalization times of less than 1 fm/c for quark and gluon matter
have been suggested by recent experiments at the Relativistic Heavy Ion
Collider (RHIC). It has been difficult to justify this rapid thermalization in
first-principle calculations based on perturbation theory or the color glass
condensate picture. Here, we address the related question of the decoherence of
the gluon field, which is a necessary component of thermalization. We present a
simplified leading-order computation of the decoherence time of a gluon
ensemble subject to an incoming flux of Weizsacker-Williams gluons. We also
discuss the entropy produced during the decoherence process and its relation to
the entropy in the final state which has been measured experimentally.Comment: 8 pages, 3 figure
Successful ablation of ventricular tachycardia with a novel multipolar high-density mapping catheter
Effects of broccoli extract and various essential oils on intestinal and faecal microflora and on xenobiotic enzymes and the antioxidant system of piglets
Objective: Since the ban of antibiotics as growth promoting feed additives in
the EU in 2006 research in alternatives has gained importance. Phytogenic feed
additives represent a heterogenous class of different plant derived substances
that are discussed to improve the health of farm animals by direct and
indirect antioxidant effects and by influencing microbial eubiosis in the
gastrointestinal tract. Consequently our study aimed to investigate the
influence of broccoli extract and the essential oils of tur- meric, oregano,
thyme and rosemary, as selected individual additives, on intestinal and faecal
microflora, on xenobiotic enzymes, and on the antioxidant system of piglets.
Methods: 48 four weeks old male weaned piglets were assigned to 6 groups of 8.
The piglets were housed individually in stainless steel pens with slatted
floor. The control group (Con) was fed a diet without an additive for 4 weeks.
The diet of group BE contained 0.15 g/kg sulforaphane in form of a broccoli
extract. 535, 282, 373 and 476 mg/kg of the essential oils of turmeric (Cuo),
oregano (Oo), thyme (To) and rosemary (Ro) were added to the diets of the
remaining 4 groups to stan-dardise supplementation to 150 mg/kg of the oils’
key terpene compounds ar-turmerone, carvacrol, thymol and 1,8-cineole. The
composition of bacterial microflora was examined by cultivating samples of
jejeunal and colonic mucosa and of faeces under specific conditions. The mRNA
expression of xenobiotic and antioxidant enzymes was determined by reversing
transcrip- tase real time detection PCR (RT-PCR). Total antioxidant status was
assayed using the Trolox Equivalent Antioxidant Capacity (TEAC), and lipid
peroxidation was determined by measuring thiobarbioturic acid reactive
substances (TBA- RS). Results: Compared to Con piglets all additives
positively influenced weight gain and feed conversion in week 1. Over the
whole trial period no significant differences in performance parameters
existed between the experimental groups. Compared to group Con performance of
Ro piglets was, however, slightly impaired. Com- pared to Con piglets Cuo, Oo
and To increased the ratio of Lactobacilli:E. coli attached to the jejunal
mucosa, whereas BE and Ro impaired this ratio slightly. In contrast in colonic
mucosa Ro improved Lactobacilli:E. coli ratio. In faecal samples an
improvement of Lactobacilli:E. coli ratio could be analysed for To and Ro. Ro
was the only additive that reduced the incidence rate of piglets tested
positive for enterotoxic E. coli (ETEC). All additives significantly increased
jejunal TEAC and reduced TBA-RS. In the liver BE, Cuo, Oo and To increased
TEAC in tendency and Ro significantly. Liver TBA-RS were slightly reduced by
all additives compared to Con piglets. Whereas the influence of BE, To and Ro
on jejunal TEAC mainly was derived from the induction of xenobiotic and
antioxidant enzymes (indirect antioxidant effects), Cuo and Oo influenced TEAC
by direct antioxidant effects. Discussion and Conclusions: Our results have
shown: That within the labiatae oils Oo and To have the potential to improve
performance slightly. That phytogenic substances have a small but not sig-
nificant influence on intestinal microflora. That phytogenic feed additives
up-regulate the anti- oxidant system of piglets either by direct or by
indirect antioxidant effects and that they may thereby improve health status.
That within the labiatae oils Oo has a high direct antioxidant potential
whereas Ro potently induces xenobiotic and antioxidant enzymes. That broccoli
extract is an attractive new phytogenic additive, improving antioxidant status
by indirect antioxidant effects. That defined combinations of selected
phytogenic substances may produce additive effects. That health promoting
effects of phytogenic additives in the future should be studied systematically
under the challenge with pathogenic microorganisms or food derived to-xins
A quantitative analysis of stratospheric HCl, HNO3, and O3 in the tropopause region near the subtropical jet
The effects of chemical two-way mixing on the Extratropical Transition Layer (ExTL) near the
subtropical jet are investigated by stratospheric tracer-tracer correlations. To this end, in situ measurements
were performed west of Africa (25–32◦N) during the Transport and Composition of the Upper Troposphere
Lower Stratosphere (UTLS)/Earth System Model Validation (TACTS/ESMVal) mission in August/September
2012. The Atmospheric chemical Ionization Mass Spectrometer sampling HCl and HNO3 was for the first
time deployed on the new German High Altitude and Long range research aircraft (HALO). Measurements
of O3, CO, European Centre for Medium-Range Weather Forecasts (ECMWF) analysis, and the tight
correlation of the unambiguous tracer HCl to O3 and HNO3 in the lower stratosphere were used to quantify
the stratospheric content of these species in the ExTL. With increasing distance from the tropopause, the
stratospheric content increased from 10% to 100% with differing profiles for HNO3 and O3. Tropospheric
fractions of 20% HNO3 and 40% O3 were detected up to a distance of 30 K above the tropopause
Changes in prescribed medicines in older patients with multimorbidity and polypharmacy in general practice
Background: Treatment complexity rises in line with the number of drugs, single doses, and administration methods, thereby threatening patient adherence. Patients with multimorbidity often need flexible, individualised treatment regimens, but alterations during the course of treatment may further increase complexity. The objective of our study was to explore medication changes in older patients with multimorbidity and polypharmacy in general practice.
Methods: We retrospectively analysed data from the cluster-randomised PRIMUM trial (PRIoritisation of MUltimedication in Multimorbidity) conducted in 72 general practices. We developed an algorithm for active pharmaceutical ingredients (API), strength, dosage, and administration method to assess changes in physician-reported medication data during two intervals (baseline to six-months: ∆1; six- to nine-months: ∆2), analysed them descriptively at prescription and patient levels, and checked for intervention effects.
Results: Of 502 patients (median age 72 years, 52% female), 464 completed the study. Changes occurred in 98.6% of patients (changes were 19% more likely in the intervention group): API changes during ∆1 and ∆2 occurred in 414 (82.5%) and 338 (67.3%) of patients, dosage alterations in 372 (74.1%) and 296 (59.2%), and changes in API strength in 158 (31.5%) and 138 (27.5%) respectively. Administration method changed in 79 (16%) of patients in both ∆1 and ∆2. Simvastatin, metformin and aspirin were most frequently subject to alterations.
Conclusion: Medication regimens in older patients with multimorbidity and polypharmacy changed frequently. These are mostly due to discontinuations and dosage alterations, followed by additions and restarts. These findings cast doubt on the effectiveness of cross-sectional assessments of medication and support longitudinal assessments where possible.
Trial registration.: 1. Prospective registration: Trial registration number: NCT01171339 ; Name of registry: ClinicalTrials.gov; Date of registration: July 27, 2010; Date of enrolment of the first participant to the trial: August 12, 2010. 2. Peer reviewed trial registration: Trial registration number: ISRCTN99526053 ; Name of registry: Controlled Trials; Date of registration: August 31, 2010; Date of enrolment of the first participant to the trial: August 12, 2010
Two-spinon dynamic structure factor of the one-dimensional S=1/2 Heisenberg antiferromagnet
The exact expression derived by Bougourzi, Couture, and Kacir for the
2-spinon contribution to the dynamic spin structure factor
of he one-dimensional =1/2 Heisenberg antiferromagnet at is evaluated
for direct comparison with finite-chain transition rates () and an
approximate analytical result previously inferred from finite- data, sum
rules, and Bethe-ansatz calculations. The 2-spinon excitations account for
72.89% of the total intensity in . The singularity structure
of the exact result is determined analytically and its spectral-weight
distribution evaluated numerically over the entire range of the 2-spinon
continuum. The leading singularities of the frequency-dependent spin
autocorrelation function, static spin structure factor, and -dependent
susceptibility are determined via sum rules.Comment: 6 pages (RevTex) and 5 figures (Postscript
Entropy Creation in Relativistic Heavy Ion Collisions
We review current ideas on entropy production during the different stages of
a relativistic nuclear collision. This includes recent results on decoherence
entropy and the entropy produced during the hydrodynamic phase by viscous
effects. We start by a discussion of decoherence caused by gluon bremsstrahlung
in the very first interactions of gluons from the colliding nuclei. We then
present a general framework, based on the Husimi distribution function, for the
calculation of entropy growth in quantum field theories, which is applicable to
the early ("glasma") phase of the collision during which most of the entropy is
generated. The entropy calculated from the Husimi distribution exhibits linear
growth when the quantum field contains unstable modes and the growth rateis
asymptotically equal to the Kolmogorov-Sina\"i (KS) entropy. We outline how the
approach can be used to investigate the problem of entropy production in a
relativistic heavy-ion reaction from first principles. Finally we discuss some
recent results on entropy production in the strong coupling limit, as obtained
from AdS/CFT duality.Comment: 34 pages, 14 figure
Increase of the mean inner Coulomb potential in Au clusters induced by surface tension and its implication for electron scattering
Electron holography in a transmission electron microscope was applied to
measure the phase shift induced by Au clusters as a function of the cluster
size. Large phase shifts Df observed for small Au clusters cannot be described
by the well-known equation Df=C_E V_0 t (C_E: interaction constant, V_0: mean
inner Coulomb potential (MIP) of bulk gold, t: cluster thickness). The rapid
increase of the Au MIP with decreasing cluster size derived from Df, can be
explained by the compressive strain of surface atoms in the cluster
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