1,086 research outputs found

    Pairing gaps from nuclear mean-field models

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    We discuss the pairing gap, a measure for nuclear pairing correlations, in chains of spherical, semi-magic nuclei in the framework of self-consistent nuclear mean-field models. The equations for the conventional BCS model and the approximate projection-before-variation Lipkin-Nogami method are formulated in terms of local density functionals for the effective interaction. We calculate the Lipkin-Nogami corrections of both the mean-field energy and the pairing energy. Various definitions of the pairing gap are discussed as three-point, four-point and five-point mass-difference formulae, averaged matrix elements of the pairing potential, and single-quasiparticle energies. Experimental values for the pairing gap are compared with calculations employing both a delta pairing force and a density-dependent delta interaction in the BCS and Lipkin-Nogami model. Odd-mass nuclei are calculated in the spherical blocking approximation which neglects part of the the core polarization in the odd nucleus. We find that the five-point mass difference formula gives a very robust description of the odd-even staggering, other approximations for the gap may differ from that up to 30% for certain nuclei.Comment: 17 pages, 8 figures. Accepted for publication in EPJ

    Consequences of the center-of-mass correction in nuclear mean-field models

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    We study the influence of the scheme for the correction for spurious center-of-mass motion on the fit of effective interactions for self-consistent nuclear mean-field calculations. We find that interactions with very simple center-of-mass correction have significantly larger surface coefficients than interactions for which the center-of-mass correction was calculated for the actual many-body state during the fit. The reason for that is that the effective interaction has to counteract the wrong trends with nucleon number of all simplified schemes for center-of-mass correction which puts a wrong trend with mass number into the effective interaction itself. The effect becomes clearly visible when looking at the deformation energy of largely deformed systems, e.g. superdeformed states or fission barriers of heavy nuclei.Comment: 12 pages LATeX, needs EPJ style files, 5 eps figures, accepted for publication in Eur. Phys. J.

    Pest Flies of Pastured Cattle and Horses

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    NYS IPM Type: Livestock Fact SheetIntegrated pest management (IPM) of pest flies, midges, and mosquitoes of pastured cattle and Horses incorporates several key components: correct arthropod pest identification, monitoring, management action (i.e., treatment), and evaluation of the action. This fact sheet is intended to help the livestock producer identify arthropod pests and not to be a how-to document. For information on the other steps to successful pest management please consult one or more of the suggested readings or web sites provided in the references section

    Integrated Management of Flies in and around Dairy and Livestock Barns

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    NYS IPM Type: Livestock Fact SheetIn the past, management of flies in dairy and livestock barns often relied solely on insecticide use. But this single-tactic approach can aggravate fly populations' resistance to insecticides and inadvertently destroy natural enemies of flies. Today successful farmers are combining careful use of pesticides with other integrated pest management (IPM) practices

    Seasonal Variation in Carcinops pumilio (Coleoptera: Histeridae) Dispersal and Potential for Suppression of Dispersal Behavior

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    Seasonal dispersal of Carcinops pumilio (Erichson) was evaluated using two trapping methods-a black-light pitfall trap and a mesh-bottomed trap placed on poultry manure. The black-light trap collected larger numbers than the mesh-bottomed trap from March through June. The mesh-bottomed trap gathered larger numbers of beetles from June through August and numbers were less variable throughout the year. Often, when very low numbers of beetles were recovered from manure cores, large numbers of beetles could be collected with the black-light trap suggesting that beetle density may not be an important factor in dispersal behavior. The greatest dispersal in the dispersal arenas (≈90%) occurred using beetles collected by both trap types in June 2000. Beginning in March and ending in August, a cyclic rise and then fall pattern in both laboratory dispersal and beetle collections was observed. Trap collection patterns were similar in both years of the study. In January and March, we were unable to prevent dispersal behavior of beetles captured in black-light traps. However, in May, after beetles had been in a dispersal phase for several months, we were able to suppress dispersal. In contrast, dispersal behavior among beetles captured with the mesh-bottomed trap did not change following the photoperiod-altered exposur

    House Fly (Musca domestica L.) Survival after Mechanical Incorporation of Poultry Manure into Field Soil

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    Land application is often a routine part of manure management. Not only is it a practical means of disposing large amounts of poultry wastes, it is an efficient use of an organic fertilizer. Unfortunately, poultry manure may contain a large number of house fly larvae and pupae that can become a nuisance if they complete development. Mechanical incorporation of poultry manure is often recommended to help reduce odor; it has also been though to reduce the potential for a fly outbreak. This study examined fly survival following burial in field soil at depths of 0, 1, 3, 6, 9, and 12 in. One quarter of the adult house flies developing from pupae were able to crawl through 12 in. of soil to reach the surface. Survival of flies buried closer to the surface was greater. We compared house fly survival following disk, harrow, and moldboard plow incorporation of manure to surface application. No method of incorporation was better than the surface application. Adult flies reached outbreak proportions 10 days following application and the outbreak lasted another 11 day

    Individual and Combined Releases of Muscidifurax raptor and M. raptorellus (Hymenoptera: Pteromalidae) as a Biological Control Tactic Targeting House Flies in Dairy Calf Facilities

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    The impact of commercially reared house fly parasitoids released into nine dairy calf coverall facilities were evaluated over 3 yr. Individual and equally mixed ratios of the pteromalid parasitoids Muscidifurax raptor Girault and Saunders and M. raptorellus Kogan and Legner were released at a rate of 500 parasitoids per calf per week for 8 wk. Prerelease, release, and postrelease parasitism was monitored using nearly 100,000 sentinel house fly, Musca domestica L., pupae during the 3 yr study. In general, very few adult parasitoids were recovered during the prerelease period and on the no-release farms during any period. However, considerable numbers of M. raptor and M. raptorellus were recovered from sentinel pupae on respective release farms. As expected, the greatest successful parasitism occurred during release periods, with a drop during postrelease periods. High successful parasitism and uneclosed pupae on M. raptorellus release farms suggests that this parasitoid was aggressive in attacking hosts with progeny production at approximately four wasps per pupa. Solitary releases of M. raptor provided sentinel mortality between 31 and 38%, whereas sentinel mortality on M. raptorellus-release farms was double, at 59-80%. Using mixed releases of the two species, overall fly mortality was slightly lower than that observed on M. raptorellus-only farms. This study documents the advantage of releasing M. raptorellus rather than M. raptor on New York dairy calf facilities, as supported by higher parasitism rates and lower costs (35-75%) for purchase of these gregarious wasps, as 75-80% fewer parasitized pupae are needed to achieve similar adult parasitoid level

    Potential energy surfaces of superheavy nuclei

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    We investigate the structure of the potential energy surfaces of the superheavy nuclei 258Fm, 264Hs, (Z=112,N=166), (Z=114,N=184), and (Z=120,N=172) within the framework of self-consistent nuclear models, i.e. the Skyrme-Hartree-Fock approach and the relativistic mean-field model. We compare results obtained with one representative parametrisation of each model which is successful in describing superheavy nuclei. We find systematic changes as compared to the potential energy surfaces of heavy nuclei in the uranium region: there is no sufficiently stable fission isomer any more, the importance of triaxial configurations to lower the first barrier fades away, and asymmetric fission paths compete down to rather small deformation. Comparing the two models, it turns out that the relativistic mean-field model gives generally smaller fission barriers.Comment: 8 pages RevTeX, 6 figure

    Impact of bileaflet mitral valve prolapse on quantification of mitral regurgitation with cardiac magnetic resonance: a single-center study.

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    To quantify mitral regurgitation (MR) with CMR, the regurgitant volume can be calculated as the difference between the left ventricular (LV) stroke volume (SV) measured with the Simpson's method and the reference SV, i.e. the right ventricular SV (RVSV) in patients without tricuspid regurgitation. However, for patients with prominent mitral valve prolapse (MVP), the Simpson's method may underestimate the LV end-systolic volume (LVESV) as it only considers the volume located between the apex and the mitral annulus, and neglects the ventricular volume that is displaced into the left atrium but contained within the prolapsed mitral leaflets at end systole. This may lead to an underestimation of LVESV, and resulting an over-estimation of LVSV, and an over-estimation of mitral regurgitation. The aim of the present study was to assess the impact of prominent MVP on MR quantification by CMR. In patients with MVP (and no more than trace tricuspid regurgitation) MR was quantified by calculating the regurgitant volume as the difference between LVSV and RVSV. LVSV <sub>uncorr</sub> was calculated conventionally as LV end-diastolic (LVEDV) minus LVESV. A corrected LVESV <sub>corr</sub> was calculated as the LVESV plus the prolapsed volume, i.e. the volume between the mitral annulus and the prolapsing mitral leaflets. The 2 methods were compared with respect to the MR grading. MR grades were defined as absent or trace, mild (5-29% regurgitant fraction (RF)), moderate (30-49% RF), or severe (≄50% RF). In 35 patients (44.0 ± 23.0y, 14 males, 20 patients with MR) the prolapsed volume was 16.5 ± 8.7 ml. The 2 methods were concordant in only 12 (34%) patients, as the uncorrected method indicated a 1-grade higher MR severity in 23 (66%) patients. For the uncorrected/corrected method, the distribution of the MR grades as absent-trace (0 vs 11, respectively), mild (20 vs 18, respectively), moderate (11 vs 5, respectively), and severe (4 vs 1, respectively) was significantly different (p < 0.001). In the subgroup without MR, LVSV <sub>corr</sub> was not significantly different from RVSV (difference: 2.5 ± 4.7 ml, p = 0.11 vs 0) while a systematic overestimation was observed with LVSV <sub>uncorr</sub> (difference: 16.9 ± 9.1 ml, p = 0.0007 vs 0). Also, RVSV was highly correlated with aortic forward flow (n = 24, R <sup>2</sup>  = 0.97, p < 0.001). For patients with severe bileaflet prolapse, the correction of the LVSV for the prolapse volume is suggested as it modified the assessment of MR severity by one grade in a large portion of patients

    Trends in work disability with mental diagnoses among social workers in Finland and Sweden in 2005-2012

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    AIMS: Social workers report high levels of stress and have an increased risk for hospitalisation with mental diagnoses. However, it is not known whether the risk of work disability with mental diagnoses is higher among social workers compared with other human service professionals. We analysed trends in work disability (sickness absence and disability pension) with mental diagnoses and return to work (RTW) in 2005-2012 among social workers in Finland and Sweden, comparing with such trends in preschool teachers, special education teachers and psychologists. METHODS: Records of work disability (>14 days) with mental diagnoses (ICD-10 codes F00-F99) from nationwide health registers were linked to two prospective cohort projects: the Finnish Public Sector study, years 2005-2011 and the Insurance Medicine All Sweden database, years 2005-2012. The Finnish sample comprised 4849 employees and the Swedish 119 219 employees covering four occupations: social workers (Finland 1155/Sweden 23 704), preschool teachers (2419/74 785), special education teachers (832/14 004) and psychologists (443/6726). The reference occupations were comparable regarding educational level. Risk of work disability was analysed with negative binomial regression and RTW with Cox proportional hazards. RESULTS: Social workers in Finland and Sweden had a higher risk of work disability with mental diagnoses compared with preschool teachers and special education teachers (rate ratios (RR) 1.43-1.91), after adjustment for age and sex. In Sweden, but not in Finland, social workers also had higher work disability risk than psychologists (RR 1.52; 95% confidence interval 1.28-1.81). In Sweden, in the final model special education teachers had a 9% higher probability RTW than social workers. In Sweden, in the final model the risks for work disability with depression diagnoses and stress-related disorder diagnoses were similar to the risk with all mental diagnoses (RR 1.40-1.77), and the probability of RTW was 6% higher in preschool teachers after work disability with depression diagnoses and 9% higher in special education teachers after work disability with stress-related disorder diagnoses compared with social workers. CONCLUSION: Social workers appear to be at a greater risk of work disability with mental diagnoses compared with other human service professionals in Finland and Sweden. It remains to be studied whether the higher risk is due to selection of vulnerable employees to social work or the effect of work-related stress in social work. Further studies should focus on these mechanisms and the risk of work disability with mental diagnoses among human service professionals
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