16,617 research outputs found
A Bayesian approach to evaluate confidence intervals in counting experiments with background
In this paper we propose a procedure to evaluate Bayesian confidence
intervals in counting experiments where both signal and background fluctuations
are described by the Poisson statistics. The results obtained when the method
is applied to the calculation of upper limits will also be illustrated.Comment: 19 pages, 6 figure
Carnivory in Adult Female Eumenid Wasps (Hymenoptera: Vespidae: Eumeninae) and Its Effect on Egg Production
Seventy captive adult female wasps of the eumenid genera Ancistrocerus and Euodynerus were observed to feed on multiple prey items. It was shown experimentally that E. foraminatus females that fed on prey had significantly larger egg volumes than adult wasps deprived of prey
Methods for Artificial Rearing of Solitary Eumenid Wasps (Hymenoptera: Vespidae: Eumeninae)
Solitary eumenid wasps of the genera Ancistrocerus and Euodynerus can be reared in small cages. Laboratory-reared larvae of the spruce budworm caterpillars, Choristoneura fumiferana (Lepidoptera: Torlricidae) are suitable prey
Charm Meson Mixing: An Experimental Review
We review current experimental results on charm mixing and CP violation. We
survey experimental techniques, including time-dependent, time-independent, and
quantum-correlated measurements. We review techniques that use a slow pion tag
from D*+ --> pi+ D0 + c.c. decays and those that do not, and cover two-body and
multi-body D0 decay modes. We provide a summary of D-mixing results to date and
comment on future experimental prospects at the LHC and other new or planned
facilities.Comment: 53 pages, 29 figures, 8 table
Variable camber rotor study
Deployment of variable camber concepts on helicopter rotors was analytically assessed. It was determined that variable camber extended the operating range of helicopters provided that the correct compromise can be obtained between performance/loads gains and mechanical complexity. A number of variable camber concepts were reviewed on a two dimensional basis to determine the usefulness of leading edge, trailing edge and overall camber variation schemes. The most powerful method to vary camber was through the trailing edge flaps undergoing relatively small motions (-5 deg to +15 deg). The aerodynamic characteristics of the NASA/Ames A-1 airfoil with 35% and 50% plain trailing edge flaps were determined by means of current subcritical and transonic airfoil design methods and used by rotor performance and loads analysis codes. The most promising variable camber schedule reviewed was a configuration with a 35% plain flap deployment in an on/off mode near the tip of a blade. Preliminary results show approximately 11% reduction in power is possible at 192 knots and a rotor thrust coefficient of 0.09. The potential demonstrated indicates a significant potential for expanding the operating envelope of the helicopter. Further investigation into improving the power saving and defining the improvement in the operational envelope of the helicopter is recommended
A comparison between detailed and configuration-averaged collisional-radiative codes applied to non-local thermal equilibrium plasma
A collisional-radiative model describing nonlocal-thermodynamic-equilibrium
plasmas is developed. It is based on the HULLAC (Hebrew University Lawrence
Livermore Atomic Code) suite for the transitions rates, in the zero-temperature
radiation field hypothesis. Two variants of the model are presented: the first
one is configuration averaged, while the second one is a detailed level
version. Comparisons are made between them in the case of a carbon plasma; they
show that the configuration-averaged code gives correct results for an
electronic temperature Te=10 eV (or higher) but fails at lower temperatures
such as Te=1 eV. The validity of the configuration-averaged approximation is
discussed: the intuitive criterion requiring that the average
configuration-energy dispersion must be less than the electron thermal energy
turns out to be a necessary but far from sufficient condition. Another
condition based on the resolution of a modified rate-equation system is
proposed. Its efficiency is emphasized in the case of low-temperature plasmas.
Finally, it is shown that near-threshold autoionization cascade processes may
induce a severe failure of the configuration-average formalism.Comment: 9
Nucleosynthesis Modes in the High-Entropy-Wind of Type II Supernovae: Comparison of Calculations with Halo-Star Observations
While the high-entropy wind (HEW) of Type II supernovae remains one of the
more promising sites for the rapid neutron-capture (r-) process, hydrodynamic
simulations have yet to reproduce the astrophysical conditions under which the
latter occurs. We have performed large-scale network calculations within an
extended parameter range of the HEW, seeking to identify or to constrain the
necessary conditions for a full reproduction of all r-process residuals
N_{r,\odot}=N_{\odot}-N_{s,\odot} by comparing the results with recent
astronomical observations. A superposition of weighted entropy trajectories
results in an excellent reproduction of the overall N_{r,\odot}-pattern beyond
Sn. For the lighter elements, from the Fe-group via Sr-Y-Zr to Ag, our HEW
calculations indicate a transition from the need for clearly different sources
(conditions/sites) to a possible co-production with r-process elements,
provided that a range of entropies are contributing. This explains recent
halo-star observations of a clear non-correlation of Zn and Ge and a weak
correlation of Sr - Zr with heavier r-process elements. Moreover, new
observational data on Ru and Pd seem to confirm also a partial correlation with
Sr as well as the main r-process elements (e.g. Eu).Comment: 15 pages, 1 table, 4 figures; To be published in the Astrophysical
Journal Letter
Difference in prevalence of common mental disorder as measured using four questionnaire delivery methods among young people in rural Zimbabwe.
BACKGROUND: Previous studies have suggested that interviewer-administered questionnaires can under-estimate the prevalence of depression and suicidal ideation when compared with self-administered ones. We report here on differences in prevalence of reporting mental health between four questionnaire delivery modes (QDM). METHODS: Mental health was assessed using the Shona Symptom Questionnaire (SSQ), a locally validated 14-item indigenous measure for common mental affective disorders. A representative sample of 1495 rural Zimbabwean adolescents (median age 18) was randomly allocated to one of four questionnaire delivery modes: self-administered questionnaire (SAQ), SAQ with audio (AASI), interviewer-administered questionnaire (IAQ), and audio computer-assisted survey instrument (ACASI). RESULTS: Prevalence of common affective disorders varied between QDM (52.3%, 48.6%, 41.5%, and 63.6% for SAQ, AASI, IAQ, and ACASI respectively (P<0.001)). Fewer participants failed to complete SSQ using IAQ and ACASI than other methods (1.6% vs. 12.3%; P<0.001). Qualitative data suggested that respondents found it difficult answering questions honestly in front of an interviewer. LIMITATIONS: Direction of accuracy cannot be ascertained due to lack of objective or clinical assessments of affective disorders. CONCLUSIONS: Estimates of prevalence of psychosomatic symptoms and suicidal ideation varied according to mode of interview. As each mode's direction of accuracy remains unresolved evaluations of interventions continue to be hampered
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