11,159 research outputs found
Strangeness from 20 AGeV to 158 AGeV
New results from the energy scan programme of NA49, in particular kaon production at 30 AGeV and phi production at 40 and 80 AGeV are presented. The K+/pi+ ratio shows a pronounced maximum at 30 AGeV; the kaon slope parameters are constant at SPS energies. Both findings support the scenario of a phase transition at about 30 AGeV beam energy. The phi/pi ratio increases smoothly with beam energy, showing an energy dependence similar to K-/pi-. The measured particle yields can be reproduced by a hadron gas model, with chemical freeze-out parameters on a smooth curve in the T-muB plane. The transverse spectra can be understood as resulting from a rapidly expanding, locally equilibrated source. No evidence for an earlier kinetic decoupling of heavy hyperons is found
Phi production in 158-GEV/u Pb + Pb collisions
Preliminary data on phi production in central Pb + Pb collisions at 158 GeV per nucleon are presented, measured by the NA49 experiment in the hadronic decay channel phi - K+K-. At mid-rapidity, the kaons were separated from pions and protons by combining dE/dx and time-of-flight information; in the forward rapidity range only dE/dx identification was used to obtain the rapidity distribution and a rapidity-integrated mt-spectrum. The mid-rapidity yield obtained was dN/dy = 1.85 ± 0.3 per event; the total phi multiplicity was estimated to be 5.0 ± 0.7 per event. Comparison with published pp data shows a slight, but not very significant strangeness enhancement
The labor market effect of demographic change: Alleviation for financing social security
The paper shows the effect of demographic change on per capita burden of financing a PAYG social security system in the standard OLG model with frictional labor markets. Rising longevity and decreasing fertility both induce a rise in the employment level via increased capital accumulation and job openings. Simulations of the theoretical model show that this labor market effect indirectly crowds out part of the initial demographic shock's direct impact on per capita financing burden. This holds true for the generation at the period of impact as well as for the following generations
Methods and methodologies for qualitative data analysis
The main aim of this paper is to introduce the contributions that are published in the proceedings. As a side-line, I follow up on an observation that I made (not only) at the conference – which is the distinction between methods and methodology. I hope that you will enjoy and benefit from reading the articles in the proceedings and watching the corresponding videos of the original presentations on the conference YouTube channel (http://www.youtube.com/user/ATLASticonference)
Computer-assisted grounded theory analysis with ATLAS.ti
In this paper I show how the various steps of a Grounded Theory analysis can be conducted in a computer-assisted environment. As the Grounded Theory approach was developed before the event of CAQDAS, the various steps and procedures have been described for manual ways of analysis. In newer books one finds references that this can of course also be accomplished in CAQDAS, but little detail is provided on the practical aspects, as if the process were self-explanatory. Based on my experience, it is not, and this applies to the application of any methodological approach in CAQDAS. Learning the various tools and features in a software does not automatically teach the user which tool is the best fit for a particular process given a particular methodological framework. In this paper I want to show how the various steps and procedures of the Strauss and Corbin approach to Grounded Theory can be translated for use in ATLAS.ti
Affine Symmetries of Orbit Polytopes
An orbit polytope is the convex hull of an orbit under a finite group . We develop a general theory of possible
affine symmetry groups of orbit polytopes. For every group, we define an open
and dense set of generic points such that the orbit polytopes of generic points
have conjugated affine symmetry groups. We prove that the symmetry group of a
generic orbit polytope is again if is itself the affine symmetry group
of some orbit polytope, or if is absolutely irreducible. On the other hand,
we describe some general cases where the affine symmetry group grows.
We apply our theory to representation polytopes (the convex hull of a finite
matrix group) and show that their affine symmetries can be computed effectively
from a certain character. We use this to construct counterexamples to a
conjecture of Baumeister et~al.\ on permutation polytopes [Advances in Math.
222 (2009), 431--452, Conjecture~5.4].Comment: v2: Referee comments implemented, last section updated. Numbering of
results changed only in Sections 9 and 10. v3: Some typos corrected. Final
version as published. 36 pages, 5 figures (TikZ
Management of skin-sparing mastectomy: Results of a survey of German Hospitals
Background: The aim of this study was to evaluate the current management of skin-sparing mastectomy in German hospitals and to determine its oncologic safety. For this purpose, 100 surgeons were surveyed regarding their use of skin-sparing mastectomy. Results: Almost all surveyed hospitals performed skin-sparing mastectomy. Most of them believe that the recurrence rate is equal to that of conventional mastectomy. 95% regard inflammatory cancer as a contraindication to skin-sparing surgery. Most of the hospitals thin out the skin without leaving any macroscopic glandular tissue behind, and 73% leave the nipple-areola complex (NAC) on the basis of frozen sections. Volume replacement is most commonly done with latissimus dorsi muscle flaps and pedicled TRAM flaps. In 76% of the surveyed hospitals, reconstruction after mastectomy is performed by the gynecological department. Conclusion: Skin-sparing mastectomy is considered to be the best cosmetic option for breast reconstruction in selected breast cancer patients. At present, statistical proof of its oncologic safety is lacking. The surgical techniques used for skin-sparing mastectomy have not yet been standardized. In order to achieve standardization, careful discussion-making and evaluation remain important
Initial '80s Development of Inflated Antennas
State of the art technology was considered in the definition and documentation of a membrane surface suitable for use in a space reflector system for long durations in orbit. Requirements for a metal foil-plastic laminate structural element were determined and a laboratory model of a rigidized element to test for strength characteristics was constructed. Characteristics of antennas ranging from 10 meters to 1000 meters were determined. The basic antenna configuration studied consists of (1) a thin film reflector, (2) a thin film cone, (3) a self-rigidizing structural torus at the interface of the cone and reflector; and (4) an inflation system. The reflector is metallized and, when inflated, has a parabolic shape. The cone not only completes the enclosure of the inflatant, but also holds the antenna feed at its apex. The torus keeps the inflated cone-reflector from collapsing inward. Laser test equipment determined the accuracy of the inflated paraboloids
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