464 research outputs found
On universality of the coupling of neutrinos to Z
We employ an effective Lagrangian approach and use LEP data to place severe
bounds on universality violations of the couplings of , , and
to the boson. Our results justify the assumption of universality
in these couplings that is usually made, as for example in the analysis of
solar neutrinos detected at SNO.Comment: 8 pages, no figures. A few comments added. It matches version to be
published in PR
Limits on the Mixing of Tau Neutrino to Heavy Neutrinos
Limits at 90 % c.l. on the square of the mixing strength |U_tau4|^2 between
nu_tau and a mostly isosinglet heavy neutrino with mass in the range 10-290
MeV/c^2 are reported. The results were derived using the negative result of a
search for neutral particles decaying into two electrons conducted by the CHARM
collaboration in a neutrino beam dump experiment. Upper limits ~10^-4 were
obtained for neutrino masses larger than 160 MeV/c^2.Comment: 10 pages, 3 figure
Sense-giving in health care: the relationship between the HR roles of line managers and employee commitment
In this article, we examine line manager prioritisation of HR roles and the consequences for employee commitment in a health-care setting. Our analysis is based on a quantitative, multi-actor study (509 employees and 67 line managers) in four Dutch hospitals. Using sense-giving as a theoretical lens, we demonstrate that, in addition to the effects of high commitment HRM, prioritising the Employee Champion role alone and the Employee Champion and Strategic Partner roles in combination is associated with higher employee commitment. We argue that through performing roles that are evocative of deep-seated values, such as excellent patient care and concern for others, line managers can have a positive effect on staff attitudes. In a sector often beleaguered by staff turnover, exhaustion and burnout, we offer an important, empirically based framework that has the potential to improve employee commitment and, from there, enhance performance
Growth forms and life-history strategies predict the occurrence of aquatic macrophytes in relation to environmental factors in a shallow peat lake complex
Aquatic ecosystems provide vital services, and macrophytes play a critical role in their functioning. Conceptual models indicate that in shallow lakes, plants with different growth strategies are expected to inhabit contrasting habitats. For shallow peat lakes, characterized by incohesive sediments, roles of growth forms, life-history strategies and environmental factors in determining the occurrence of aquatic vegetation remain unknown. In a field survey, we sampled 64 points in a peat lake complex and related macrophyte occurrence to growth forms (floating-leaved rooted and submerged), life-history strategies for overwintering (turions, seeds, rhizomes) and environmental factors (water depth, fetch, and porewater nutrients). Our survey showed that macrophyte occurrence relates to water depth, wind-fetch, and nutrients, and depends on growth form and life-history strategies. Specifically, rooted floating-leaved macrophytes occur at lower wind-fetch/shallower waters. Submerged macrophytes occur from low to greater wind-fetch/water depth, depending on life-history strategies; macrophytes with rhizomes occur at greater wind-fetch/depth relative to species that overwinter with seeds or turions. We conclude that growth form and life-history strategies for overwintering predict macrophytes occurrence regarding environmental factors in peat lakes. Therefore, we propose an adapted model for macrophyte occurrence for such lakes. Altogether, these results may aid in species-selection to revegetate peat lakes depending on its environment
The nursery function of artificial floodplain habitats in the lower Rhine and Meuse for riverine fish
Contains fulltext :
202317.pdf (publisher's version ) (Open Access)14th NCR-days 201
Effects of Marine Reserves versus Nursery Habitat Availability on Structure of Reef Fish Communities
No-take marine fishery reserves sustain commercial stocks by acting as buffers against overexploitation and enhancing fishery catches in adjacent areas through spillover. Likewise, nursery habitats such as mangroves enhance populations of some species in adjacent habitats. However, there is lack of understanding of the magnitude of stock enhancement and the effects on community structure when both protection from fishing and access to nurseries concurrently act as drivers of fish population dynamics. In this study we test the separate as well as interactive effects of marine reserves and nursery habitat proximity on structure and abundance of coral reef fish communities. Reserves had no effect on fish community composition, while proximity to nursery habitat only had a significant effect on community structure of species that use mangroves or seagrass beds as nurseries. In terms of reef fish biomass, proximity to nursery habitat by far outweighed (biomass 249% higher than that in areas with no nursery access) the effects of protection from fishing in reserves (biomass 21% lower than non-reserve areas) for small nursery fish (≤25 cm total length). For large-bodied individuals of nursery species (>25 cm total length), an additive effect was present for these two factors, although fish benefited more from fishing protection (203% higher biomass) than from proximity to nurseries (139% higher). The magnitude of elevated biomass for small fish on coral reefs due to proximity to nurseries was such that nursery habitats seem able to overrule the usually positive effects on fish biomass by reef reserves. As a result, conservation of nursery habitats gains importance and more consideration should be given to the ecological processes that occur along nursery-reef boundaries that connect neighboring ecosystems
A scheme with two large extra dimensions confronted with neutrino physics
We investigate a particle physics model in a six-dimensional spacetime, where
two extra dimensions form a torus. Particles with Standard Model charges are
confined by interactions with a scalar field to four four-dimensional branes,
two vortices accommodating ordinary type fermions and two antivortices
accommodating mirror fermions. We investigate the phenomenological implications
of this multibrane structure by confronting the model with neutrino physics
data.Comment: LATEX, 24 pages, 9 figures, minor changes in the tex
Measurement of electron-neutrino electron elastic scattering
The cross section for the elastic scattering reaction nu_e+e- -> nu_e+e- was
measured by the Liquid Scintillator Neutrino Detector using a mu+ decay-at-rest
nu_e beam at the Los Alamos Neutron Science Center. The standard model of
electroweak physics predicts a large destructive interference between the
charge current and neutral current channels for this reaction. The measured
cross section, sigma_{nu_e e-}=[10.1 +- 1.1(stat.) +- 1.0(syst.)]x E_{nu_e}
(MeV) x 10^{-45} cm^2, agrees well with standard model expectations. The
measured value of the interference parameter, I=-1.01 +- 0.13(stat.) +-
0.12(syst.), is in good agreement with the standard model expectation of
I^{SM}=-1.09. Limits are placed on neutrino flavor-changing neutral currents.
An upper limit on the muon-neutrino magnetic moment of 6.8 x 10^{-10} mu_{Bohr}
is obtained using the nu_mu and \bar{nu}_mu fluxes from pi+ and mu+ decay.Comment: 22 pages, 11 figure
Extending Sensitivity for Low-Mass Neutral Heavy Lepton Searches
We point out the importance of two-body final states of weak isosinglet
neutral heavy leptons predicted in several models of new physics beyond the
standard model. We concentrate on muon-type neutral heavy leptons
with mass GeV which can be searched for with increased sensitivity at a
new round of neutrino experiments at CERN and Fermilab. Providing explicit
decay rate formulae for the , , , ,
, and final states, we use general scaling features to
estimate sensitivity of searches in current and future experiments,
emphasizing the importance of the decay mode.Comment: 14 pages, 8 figure
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