407 research outputs found
Comparison of relativistic bound-state calculations in Front-Form and Instant-Form Dynamics
Using the Wick-Cutkosky model and an extended version (massive exchange) of
it, we have calculated the bound states in a quantum field theoretical
approach. In the light-front formalism we have calculated the bound-state mass
spectrum and wave functions. Using the Terent'ev transformation we can write
down an approximation for the angular dependence of the wave function. After
calculating the bound-state spectra we characterized all states found.
Similarly, we have calculated the bound-state spectrum and wave functions in
the instant-form formalism. We compare the spectra found in both forms of
dynamics in the ladder approximation and show that in both forms of dynamics
the O(4) symmetry is broken.Comment: 22 pages Latex, 7 figures, style file amssymb use
Graph realizations constrained by skeleton graphs
In 2008 Amanatidis, Green and Mihail introduced the Joint Degree Matrix (JDM)
model to capture the fundamental difference in assortativity of networks in
nature studied by the physical and life sciences and social networks studied in
the social sciences. In 2014 Czabarka proposed a direct generalization of the
JDM model, the Partition Adjacency Matrix (PAM) model. In the PAM model the
vertices have specified degrees, and the vertex set itself is partitioned into
classes. For each pair of vertex classes the number of edges between the
classes in a graph realization is prescribed. In this paper we apply the new
{\em skeleton graph} model to describe the same information as the PAM model.
Our model is more convenient for handling problems with low number of partition
classes or with special topological restrictions among the classes. We
investigate two particular cases in detail: (i) when there are only two vertex
classes and (ii) when the skeleton graph contains at most one cycle.Comment: 19 page
Pharmacologic and clinical aspects of isolated hepatic perfusion (IHP) of liver metastases of solid tumours
Isolated hepatic perfusion (IHP) involves complete vascular isolation of the liver to allow local treatment of the liver. During this procedure the blood circulation of the liver is temporarily isolated from the systemic circulation. Although IHP made a promising start in the early 90s, currently it is faced by many challenges. In view of recent developments in systemic treatment, the absence of significant improvement of the technique and the lack of new applicable agents, IHP should not be considered a standard treatment option for colorectal cancer patients with isolated liver metastases. Possibly, a role still exists for IHP in the treatment of liver metastases from non-colorectal cancer origin. Whether under these circumstances, IHP can still attract the interest of both clinical and surgical oncologists necessary for further improvements, remains the question.Bronovo Research Foundation, SKOL, Amgen BV, Novartis Pharma BV, Pfi zer BV, GlaxoSmithKline, Astrazenica BV, Sanofi -aventis BV, MSD BV, Bayer BV, Abbot BV and Roche Nederland BVUBL - phd migration 201
Techniques for solving bound state problems
We have used different methods to obtain the bound states of a Hamiltonian of a relativistic two scalar particle system in a local potential. The potentials we are interested in are binding and confining potentials, that are associated with particle exchange. The issues we concentrate on when comparing the different methods are ease of numerical implementation, accuracy and stability. To check our codes we have made use of several potentials for which the bound states are known in the nonrelativistic situation. Finally we calculate the bound states for the Yukawa potential in the relativistic situation and look at the collapse of the wave functions in this situation
Een diploma dat erkend wordt
Uitleg over een nieuwe regeling voor het bijenteeltonderwijs. Omdat het in de praktijk voor veel verenigingen onmogelijk geworden is om via een AOC een cursus te organiseren, heeft de georganiseerde bijenhouderij zelf de verantwoordelijkheid genomen. Als verenigingen een cursus organiseren die overeenstemt met de richtlijnen kunnen zij de cursisten een diploma verstrekken dat erkend wordt door de beroepsgroep van imkers en de bijenhoudersorganisatie
A Note on Encodings of Phylogenetic Networks of Bounded Level
Driven by the need for better models that allow one to shed light into the
question how life's diversity has evolved, phylogenetic networks have now
joined phylogenetic trees in the center of phylogenetics research. Like
phylogenetic trees, such networks canonically induce collections of
phylogenetic trees, clusters, and triplets, respectively. Thus it is not
surprising that many network approaches aim to reconstruct a phylogenetic
network from such collections. Related to the well-studied perfect phylogeny
problem, the following question is of fundamental importance in this context:
When does one of the above collections encode (i.e. uniquely describe) the
network that induces it? In this note, we present a complete answer to this
question for the special case of a level-1 (phylogenetic) network by
characterizing those level-1 networks for which an encoding in terms of one (or
equivalently all) of the above collections exists. Given that this type of
network forms the first layer of the rich hierarchy of level-k networks, k a
non-negative integer, it is natural to wonder whether our arguments could be
extended to members of that hierarchy for higher values for k. By giving
examples, we show that this is not the case
Answering biological questions: querying a systems biology database for nutrigenomics
The requirement of systems biology for connecting different levels of biological research leads directly to a need for integrating vast amounts of diverse information in general and of omics data in particular. The nutritional phenotype database addresses this challenge for nutrigenomics. A particularly urgent objective in coping with the data avalanche is making biologically meaningful information accessible to the researcher. This contribution describes how we intend to meet this objective with the nutritional phenotype database. We outline relevant parts of the system architecture, describe the kinds of data managed by it, and show how the system can support retrieval of biologically meaningful information by means of ontologies, full-text queries, and structured queries. Our contribution points out critical points, describes several technical hurdles. It demonstrates how pathway analysis can improve queries and comparisons for nutrition studies. Finally, three directions for future research are given
Posaconazole Tablet Pharmacokinetics: Lack of Effect of Concomitant Medications Altering Gastric pH and Gastric Motility in Healthy Subjects.
Posaconazole oral suspension is an extended-spectrum triazole that should be taken with food to maximize absorption. A new posaconazole tablet formulation has demonstrated improved bioavailability over the oral suspension in healthy adults in a fasting state. This study evaluated the effects of concomitant medications altering gastric pH (antacid, ranitidine, and esomeprazole) and gastric motility (metoclopramide) on the pharmacokinetics of posaconazole tablets. This was a prospective open-label 5-way crossover study in 20 healthy volunteers. In each treatment period, a single 400-mg dose (4 100-mg tablets) of posaconazole was administered alone or with 20 ml antacid (2 g of aluminum hydroxide and 2 g of magnesium hydroxide), ranitidine (150 mg), esomeprazole (40 mg), or metoclopramide (15 mg). There was a â„10-day washout between treatment periods. Posaconazole exposure, time to maximum concentration of drug in serum (Tmax), and apparent terminal half-life (t1/2) were similar when posaconazole was administered alone or with medications affecting gastric pH and gastric motility. Geometric mean ratios (90% confidence intervals [CIs]) of the area under the concentration-time curve from time zero to infinity (AUC0-inf) (posaconazole with medications affecting gastric pH and gastric motility versus posaconazole alone) were 1.03 (0.88-1.20) with antacid, 0.97 (0.84-1.12) with ranitidine, 1.01 (0.87-1.17) with esomeprazole, and 0.93 (0.79-1.09) with metoclopramide. Geometric mean ratios (90% CIs) of the maximum concentration of drug in serum (Cmax) were 1.06 (0.90-1.26) with antacid, 1.04 (0.88-1.23) with ranitidine, 1.05 (0.89-1.24) with esomeprazole, and 0.86 (0.73-1.02) with metoclopramide. In summary, in healthy volunteers, the pharmacokinetics of a single 400-mg dose of posaconazole tablets was not altered to a clinically meaningful extent when posaconazole was administered alone or with medications affecting gastric pH or gastric motility
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