522 research outputs found
Finite-volume effects on octet-baryon masses in covariant baryon chiral perturbation theory
We study finite-volume effects on the masses of the ground-state octet
baryons using covariant baryon chiral perturbation theory (ChPT) up to
next-to-leading order by analyzing the latest lattice Quantum
ChromoDynamics (LQCD) results from the NPLQCD collaboration. Contributions of
virtual decuplet baryons are taken into account using the "consistent" coupling
scheme. We compare our results with those obtained from heavy baryon ChPT and
show that, although both approaches can describe well the lattice data, the
underlying physics is different: In HBChPT, virtual decuplet baryons play a
more important role than they do in covariant ChPT. This is because the virtual
octet baryon contributions to finite-volume corrections are larger in covariant
ChPT than in HBChPT, while the contributions of intermediate decuplet baryons
are smaller, because of relativistic effects. We observe that for the octet
baryon masses, at fixed () finite-volume corrections decrease
as approaches its physical value, provided that the strange quark mass
is at or close to its physical value, as in most LQCD setups.Comment: 15 pages, 5 figure
Low-energy interactions of Nambu-Goldstone bosons with mesons in covariant chiral perturbation theory
We calculate the scattering lengths of Nambu-Goldstone bosons interacting
with mesons in a covariant formulation of chiral perturbation theory, which
satisfies heavy-quark spin symmetry and analytical properties of loop
amplitudes. We compare our results with previous studies performed using heavy
meson chiral perturbation theory and show that recoil corrections are sizable
in most cases.Comment: 3 figures and 4 table
Buchbesprechungen aus Botanik und Naturschutz in Hessen Bd. 20
Folgende Publikationen werden rezensiert: Garve & al.: Verbreitungsatlas Niedersachsen, Hölzel & al.: Stromtalwiesen, Lübcke & Frede: Naturschutzgebiete in Hessen Band 4, Notizbuch 68 der Kasseler Schule, Riecken & al.: Rote Liste Biotoptypen, Schulz & Dengler: Verbreitungsatlas Moose Schleswig-Holstein, Szabo: Wandern – Erkennen – Heile
Association of Lymphatic Abnormalities with Early Complications after Fontan Operation.
BACKGROUND
 Increased central venous pressure is inherent in Fontan circulation but not strongly related to Fontan complication. Abnormalities of the lymphatic circulation may play a crucial role in early Fontan complications.
METHODS
 This was a retrospective, single-center study of patients undergoing Fontan operation from 2008 to 2015. The primary outcome was significant early Fontan complication defined as secondary in-hospital treatment due to peripheral edema, ascites, pleural effusions, protein-losing enteropathy, or plastic bronchitis. All patients received T2-weighted magnetic resonance images to assess abdominal and thoracic lymphatic perfusion pattern 6 months after Fontan completion with respect to localization, distribution, and extension of lymphatic perfusion pattern (type 1-4) and with application of an area score (0-12 points).
RESULTS
 Nine out of 42 patients developed early Fontan complication. Patients with complication had longer chest tube drainage (mean 28 [interquartile range [IQR]: 13-60] vs. 13 [IQR: 2-22] days, p = 0.01) and more often obstructions in the Fontan circuit 6 months after surgery (56 vs. 15%, p = 0.02). Twelve patients showed little or no abnormalities of lymphatic perfusion (lymphatic perfusion pattern type 1). Most frequently magnetic resonance imaging showed lymphatic congestion in the supraclavicular region (24/42 patients). Paramesenteric lymphatic congestion was observed in eight patients. Patients with early Fontan complications presented with higher lymphatic area score (6 [min-max: 2-10] vs. 2 [min-max: 0-8]), p = 0.001) and greater distribution and extension of thoracic lymphatic congestion (type 3-4: n = 5/9 vs. n = 1/33, p = 0.001).
CONCLUSION
 Early Fontan complication is related to hemodynamic factors such as circuit obstruction and to the occurrence and extent of lymphatic congestion
DBRepo: a Semantic Digital Repository for Relational Databases
Data curation is a complex, multi-faceted task. While dedicated data stewards are starting to take care of these activities in close collaboration with researchers for many types of (usually file-based) data in many institutions, this is rarely yet the case for data held in relational databases. Beyond large-scale infrastructures hosting e.g. climate or genome data, researchers usually have to create, build and maintain their database, care about security patches, and feed data into it in order to use it in their research. Data curation, if at all, usually happens after a project is finished, when data may be exported for digital preservation into file repository systems.
We present DBRepo, a semantic digital repository for relational databases in a private cloud setting designed to (1) host research data stored in relational databases right from the beginning of a research project, (2) provide separation of concerns, allowing the researchers to focus on the domain aspects of the data and their work while bringing in experts to handle classic data management tasks, (3) improve findability, accessibility and reusability by offering semantic mapping of metadata attributes, and (4) focus on reproducibility in dynamically evolving data by supporting versioning and precise identification/cite-ability for arbitrary subsets of data. 
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Microstructure and Deformation Response of TRIP-Steel Syntactic Foams to Quasi-Static and Dynamic Compressive Loads
The implementation of hollow S60HS glass microspheres and Fillite 106 cenospheres in a martensitically transformable AISI 304L stainless steel matrix was realized by means of metal injection molding of feedstock with varying fractions of the filler material. The so-called TRIP-steel syntactic foams were studied with respect to their behavior under quasi-static compression and dynamic impact loading. The interplay between matrix material behavior and foam structure was discussed in relation to the findings of micro-structural investigations, electron back scatter diffraction EBSD phase analyses and magnetic measurements. During processing, the cenospheres remained relatively stable retaining their shape while the glass microspheres underwent disintegration associated with the formation of pre-cracked irregular inclusions. Consequently, the AISI 304L/Fillite 106 syntactic foams exhibited a higher compression stress level and energy absorption capability as compared to the S60HS-containing variants. The α′ -martensite kinetic of the steel matrix was significantly influenced by material composition, strain rate and arising deformation temperature. The highest ferromagnetic α′-martensite phase fraction was detected for the AISI 304L/S60HS batches and the lowest for the TRIP-steel bulk material. Quasi-adiabatic sample heating, a gradual decrease in strain rate and an enhanced degree of damage controlled the mechanical deformation response of the studied syntactic foams under dynamic impact loading
Nucleon Structure Functions from Relativistic Constituent Quarks
We investigate deep inelastic lepton scattering from the nucleon within a
constituent quark picture, in which the internal structure of constituent
quarks is modeled by meson and diquark dressing. In a covariant framework this
structure leads to a breakdown of the factorization necessary for a convolution
formulation. We perform our analysis in time-ordered perturbation theory in the
infinite momentum frame where factorization of subprocesses is automatic.
Numerical results are compared with recent data on valence quark distributions
in the proton.Comment: 10 pages LaTeX, 3 figures available upon request, TPR-94-7, to appear
in Physics Letters
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