4,558 research outputs found
Unusual synchronization phenomena during electrodissolution of silicon: the role of nonlinear global coupling
The photoelectrodissolution of n-type silicon constitutes a convenient model
system to study the nonlinear dynamics of oscillatory media. On the silicon
surface, a silicon oxide layer forms. In the lateral direction, the thickness
of this layer is not uniform. Rather, several spatio-temporal patterns in the
oxide layer emerge spontaneously, ranging from cluster patterns and turbulence
to quite peculiar dynamics like chimera states. Introducing a nonlinear global
coupling in the complex Ginzburg-Landau equation allows us to identify this
nonlinear coupling as the essential ingredient to describe the patterns found
in the experiments. The nonlinear global coupling is designed in such a way, as
to capture an important, experimentally observed feature: the spatially
averaged oxide-layer thickness shows nearly harmonic oscillations. Simulations
of the modified complex Ginzburg-Landau equation capture the experimental
dynamics very well.Comment: To appear as a chapter in "Engineering of Chemical Complexity II"
(eds. A.S. Mikhailov and G.Ertl) at World Scientific in Singapor
Conditional quasi-exact solvability of the quantum planar pendulum and of its anti-isospectral hyperbolic counterpart
We have subjected the planar pendulum eigenproblem to a symmetry analysis
with the goal of explaining the relationship between its conditional
quasi-exact solvability (C-QES) and the topology of its eigenenergy surfaces,
established in our earlier work [Frontiers in Physical Chemistry and Chemical
Physics 2, 1-16, (2014)]. The present analysis revealed that this relationship
can be traced to the structure of the tridiagonal matrices representing the
symmetry-adapted pendular Hamiltonian, as well as enabled us to identify many
more -- forty in total to be exact -- analytic solutions. Furthermore, an
analogous analysis of the hyperbolic counterpart of the planar pendulum, the
Razavy problem, which was shown to be also C-QES [American Journal of Physics
48, 285 (1980)], confirmed that it is anti-isospectral with the pendular
eigenproblem. Of key importance for both eigenproblems proved to be the
topological index , as it determines the loci of the intersections
(genuine and avoided) of the eigenenergy surfaces spanned by the dimensionless
interaction parameters and . It also encapsulates the conditions
under which analytic solutions to the two eigenproblems obtain and provides the
number of analytic solutions. At a given , the anti-isospectrality
occurs for single states only (i.e., not for doublets), like C-QES holds solely
for integer values of , and only occurs for the lowest eigenvalues of
the pendular and Razavy Hamiltonians, with the order of the eigenvalues
reversed for the latter. For all other states, the pendular and Razavy spectra
become in fact qualitatively different, as higher pendular states appear as
doublets whereas all higher Razavy states are singlets
Registered Cartels in Austria. An Overview
Cartels were legal to a large extent in Austria until the country's EU accession in 1995. We examine archival material on registered horizontal cartels to learn about their inner working. Applying content analysis to legally binding cartel contracts, we comprehensively document different collusion methods along the lines described by Stigler (1964). Quota cartels employ regular reporting schemes and use compensation mechanisms for departures from set quotas. Specialisation cartels divide markets and rely the least on information exchange and punishment. Price and payment condition cartels primarily aim to prevent secret price cuts, requiring information provision upon request, allow for discretionary decision-taking and (sometimes immediate) punishment. These stylised facts on the contractual arrangements suggest that the possibility to write legally binding agreements was employed to address the usual obstacles to sustaining collusion
Induction of Gynogenesis in Muskellunge With Irradiated Sperm of Yellow Perch Proves Diploid Muskellunge Male Homogamety
Diploid gynogenesis was induced in muskellunge Esox masquinongy using UV-irradiated muskellunge sperm as the first step in producing monosex females. In this approach, we have to rely on negative controls as an indirect reference for sperm genetic material destruction. In the first experiment, equal proportions of gynogenetic females and males were produced. Negative controls, UV-irradiated sperm without heat shock, yielded some normal hatching larvae, described as spontaneous diploids. In the second experiment, muskellunge eggs were activated using sperm from yellow perch. Because hybrids between these species are not viable, we produced unambiguous gynogens. When UV-irradiated yellow perch sperm was used to inseminate muskellunge eggs, haploids resulted (22.5% ± 2.8% survival to the eyed stage). To produce diploid gynogens, a heat shock of 31°C was applied to inseminated eggs 20 min after activation for a duration of 6 min. This process yielded several hundreds of gynogens for rearing. Several treatments of masculinizing hormone, 17 α-methyltestosterone (MT), were carried out. Fish were dissected and gonads examined histologically for sex determination. Gynogens produced using yellow-perch sperm confirmed the presence of males in the control group, whereas the MT bath treatment (400 μg/liter) resulted in the production of fish with ovotestis. These results provide evidence for male homogamety in muskellunge and imply that a change of strategy is needed to produce monosex populations.Funding for this project was provided by the Federal Aid in Sport Fish Restoration Program (F-69-P, Fish Management in Ohio), administered jointly by the U.S. Fish and Wildlife Service and the Ohio Division of Wildlife
Registered cartels in Austria: An overview
Cartels were legal to a large extent in Austria until the country's EU Accession in 1995. We examine archival material on registered horizontal cartels to learn about their inner working. Applying content analysis to legally binding cartel contracts, we comprehensively document different collusion methods along the lines described by Stigler (1964). Quota cartels employ regular reporting schemes and use compensation mechanisms for departures from set quotas. Specialization cartels divide markets, and rely the least on information exchange and punishment. Price and payment condition cartels primarily aim to prevent secret price cuts, requiring information provision upon request, allow for discretionary decision-taking and (sometimes immediate) punishment. These stylized facts on the contractual arrangements suggest that the possibility to write legally binding agreements was employed to address the usual obstacles to sustaining collusion
Strengths of the resonances at 436, 479, 639, 661, and 1279 keV in the Ne(p,)Na reaction
The Ne(p,)Na reaction is included in the neon-sodium
cycle of hydrogen burning. A number of narrow resonances in the Gamow window
dominates the thermonuclear reaction rate. Several resonance strengths are only
poorly known. As a result, the Ne(p,)Na thermonuclear
reaction rate is the most uncertain rate of the cycle. Here, a new experimental
study of the strengths of the resonances at 436, 479, 639, 661, and 1279 keV
proton beam energy is reported. The data have been obtained using a tantalum
target implanted with Ne. The strengths of the resonances
at 436, 639, and 661 keV have been determined with a relative approach, using
the 479 and 1279 keV resonances for normalization. Subsequently, the ratio of
resonance strengths of the 479 and 1279 keV resonances was determined,
improving the precision of these two standards. The new data are consistent
with, but more precise than, the literature with the exception of the resonance
at 661 keV, which is found to be less intense by one order of magnitude. In
addition, improved branching ratios have been determined for the gamma decay of
the resonances at 436, 479, and 639 keV.Comment: Final version, now using the Kelly et al. (2015) data [15] for
normalization; 10 pages, 7 figures, 3 table
Strength of the =1.842 MeV resonance in the Ca(p,)Sc reaction revisited
The strength of the MeV resonance in the
Ca(p,)Sc reaction is determined with two different
methods: First, by an absolute strength measurement using calcium hydroxide
targets, and second, relative to the well-determined strength of the resonance
triplet at = 4.5 MeV in the Ca(,)Ti
reaction. The present new value of eV is 37%
(equivalent to ) higher than the evaluated literature value. In
addition, the ratio of the strengths of the 1.842 MeV
Ca(p,)Sc and 4.5 MeV
Ca(,)Ti resonances has been determined to be
. The newly corrected strength of the 1.842-MeV resonance can
be used in the future as a normalization point for experiments with calcium
targets.Comment: Submitted to Phys. Rev.
Grundlegende betrachtungen zur wirkung eines "inversen" spanungsverhältnisses als basis für die fräswerk-zeugkonstruktion
The demand for higher productivity and quality, flexibility as well as process safety are marking the development in the field of metal-cutting manufacturing process. Thereby the field of low vibration milling plays a special role. Therefore the development and design of modern milling tools is more and more often affected by novel machining strategies. The article deals with the development and design of a low vibration milling tool including the reversal of conventional chip- cross- section b/h > 1 to the "invers" ratio b/h < 1. For this the difference between the two cross sections will be analysed. The focus of the first experimental research is the determination of the effects of reversing the chip- cross- section on the cutting forces as well as chip formation and - forming. The influence of the tool side rake angle (γf) in milling with "inverse" chip- cross- section will be studied. The results gathered in the field of "inverse" chip- cross- ratio provides the base for formulation of design fundamentals and drafts of a novel milling tool with peeling function
The shaded side of the UHC cube: a systematic review of human resources for health management and administration in social health protection schemes
Managers and administrators in charge of social protection and health financing, service purchasing and provision play a crucial role in harnessing the potential advantage of prudent organization, management and purchasing of health services, thereby supporting the attainment of Universal Health Coverage. However, very little is known about the needed quantity and quality of such staff, in particular when it comes to those institutions managing mandatory health insurance schemes and purchasing services. As many health care systems in low- and middle-income countries move towards independent institutions (both purchasers and providers) there is a clear need to have good data on staff and administrative cost in different social health protection schemes as a basis for investing in the development of a cadre of health managers and administrators for such schemes. We report on a systematic literature review of human resources in health management and administration in social protection schemes and suggest some aspects in moving research, practical applications and the policy debate forward
Disease burden of rotavirus gastroenteritis in children up to 5years of age in two Swiss cantons: paediatrician- and hospital-based surveillance
Rotavirus gastroenteritis (RV GE) is a leading cause of diarrhoea in young children. The purpose of this epidemiological surveillance was to measure the disease burden of RV GE among children <5years of age in two regions of Switzerland, Geneva and Lucerne. One hospital and four paediatricians participated per region. The surveillance lasted from December 2006 to June 2007. The population denominator for calculation of the RV GE incidence rate was the average of the overall study population <5years of age under surveillance during the surveillance period. At the study sites, 513 children with GE were presented. Stool sample was collected and examined in 341 cases, of which 130 were RV positive (38.1%). Informed consent to participate in the study was obtained for 113 RV positive subjects. The overall RV GE incidence rate was 0.97% in Lucerne [lower incidence interval (LCI), 0.71%; upper incidence interval (UCI), 1.2%] compared with 0.65 and in Geneva (LCI, 0.50%; UCI, 0.81%). Disease severity assessments using the Vescari score showed that the RV GE episodes were more severe in Lucerne than in Geneva (14.05 ± 3.05 vs 12.85 ± 2.87), which was confirmed by a higher hospitalisation rate in Lucerne at the study visit (82.9% vs 23.6%). More children had fever in Geneva than in Lucerne (42.9% vs 26.8%), and more children were hospitalised during the follow-up period in Geneva than in Lucerne (14.5% vs 2.5%). Genotyping of RV positive stool samples revealed that both G1 and P8 were the most prevalent types in both regions. There was a statistically significant difference in the distribution frequency of G1 between the two regions (p = 0.039). Assessment of health economic data confirmed the economic burden of RV GE episodes. In conclusion, RV GE episodes are a health burden as well as an economic burden also for the children in a developed country such as Switzerlan
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