1,266 research outputs found
The effects of the disposal of organophosphate and synthetic pyrethroid sheep dips on non-target organisms on farmland
The 1998 Groundwater Regulations required spent organophosphate and synthetic pyrethroid sheep dip to be disposed to farmland. The effects of dip disposal on soil invertebrates and the possible consequences for their bird predators were investigated on farms across Britain between 1999 and 2002.A preliminary survey of dip disposal practice on 42 hill farms on, or adjacent to SSSls that support breeding waders, exposed a wide variety of practices and considerable deviation from the recommended procedures in many cases. Paired disposal and control sites were sampled on a subset of the surveyed farms. Invertebrate abundance was estimated by taking soil samples, followed by Berlese extraction (or hand sorting for worms), pitfall trapping and suction sampling. Invertebrate densities on disposal sites were significantly lower than on control sites in 7 out of 15 cases and the multivariate analysis indicated significant effects of dip disposal on carabid, but not spider, species composition six months after application. Density reductions were greatest on areas that had been used for dip disposal over many years. Plots were set up in a "Latin-square" design on two experimental farms, allowing comparison of the effects of the two insecticides at two dilutions under controlled conditions. The same sampling methods were used as on the farm sites and densities of all invertebrate groups, except linyphiid spiders and carabid beetles, were significantly reduced on the disposal plots on one or more sampling occasion after application. Soil surface invertebrates taken by suction sampling showed the most severe and consistent reductions. A risk assessment suggests that spring disposal could compromise upland wading chick survival. However, the current scale of dip disposal in Britain does not pose a threat to whole bird populations
Tracing Nitrogen in Volcanic and Geothermal Volatiles from the Nicaraguan Volcanic Front
We report new chemical and isotopic data from 26 volcanic and geothermal gases, vapor condensates, and thermal water samples,
collected along the Nicaraguan volcanic front. The samples were analyzed for chemical abundances and stable isotope compositions,
with a focus on nitrogen abundances and isotope ratios. These data are used to evaluate samples for volatile contributions from magma,
air, air-saturated water, and the crust. Samples devoid of crustal contamination (based upon He isotope composition) but slightly contaminated
by air or air-saturated water are corrected using N2/Ar ratios in order to obtain primary magmatic values, composed of contributions
from upper mantle and subducted hemipelagic sediment on the down-going plate. Using a mantle endmember with
d15N= 5&and N2/He = 100 and a subducted sediment component with d15N=+7& and N2/He = 10,500, the average sediment contribution
to Nicaraguan volcanic and geothermal gases was determined to be 71%. Most of the gases were dominated by sediment-derived
nitrogen, but gas from Volca´n Mombacho, the southernmost sampling location, had a mantle signature (46% from subducted
sediment, or 54% from the mantle) and an affinity with mantle-dominated gases discharging from Costa Rica localities to the south. High
CO2/N2 exc. ratios (N2 exc. is the N2 abundance corrected for contributions from air) in the south are similar to those in Costa Rica, and
reflect the predominant mantle wedge input, whereas low ratios in the north indicate contribution by altered oceanic crust and/or preferential
release of nitrogen over carbon from the subducting slab. Sediment-derived nitrogen fluxes at the Nicaraguan volcanic front,
estimated by three methods, are 7.8 · 108 mol N/a from 3He flux, 6.9 · 108 mol/a from SO2 flux, and 2.1 · 108 and 1.3 · 109 mol/a from
CO2 fluxes calculated from 3He and SO2, respectively. These flux results are higher than previous estimates for Central America, reflecting
the high sediment-derived volatile contribution and the high nitrogen content of geothermal and volcanic gases in Nicaragua. The
fluxes are also similar to but higher than estimated hemipelagic nitrogen inputs at the trench, suggesting addition of N from altered oceanic
basement is needed to satisfy these flux estimates. The similarity of the calculated input of N via the trench to our calculated outputs
suggests that little or none of the subducted nitrogen is being recycled into the deeper mantle, and that it is, instead, returned to the
surface via arc volcanism
Ontwikkelingen van vis en visserij in de Nederlandse Waddenzee
Voor veel vissoorten is de Waddenzee een belangrijk opgroeigebied. Voor veel andere soorten vormt de ondiepe, relatief voedselrijke Waddenzee een belangrijk leefgebied. Ze trekken er door heen, brengen er een deel van het jaar of hun hele leven door. Maar hoe is het eigenlijk gesteld met de vis in de Waddenzee? Een gebied dat tevens intensief gebruikt wordt door de visserij
Localized surface states in HTSC: Alternative mechanism of zero-bias conductance peaks
It is shown that the quasiparticle states localized in the vicinity of
surface imperfections of atomic size can be responsible for the zero-bias
tunneling conductance peaks in high-Tc superconductors. The contribution from
these states can be easily separated from other mechanisms using their
qualitatively different response on an external magnetic field.Comment: REVTeX, 4 pages, 2 figs; to be published in PR
The Scottish Mental Survey 1932 linked to the Midspan studies: a prospective investigation of childhood intelligence and future health
The Scottish Mental Survey of 1932 (SMS1932) recorded mental ability test scores for nearly all of the age group of children born in 1921 and at school in Scotland on 1st June 1932. The Collaborative and Renfrew/Paisley studies, two of the Midspan studies, obtained health and social data by questionnaire and a physical examination in the 1970s. Some Midspan participants were born in 1921 and may have taken part in the SMS1932, so might have mental ability data available from childhood. The 1921-born Midspan participants were matched with the computerised SMS1932 database. The total numbers successfully matched were 1032 out of 1251 people (82.5%). Of those matched, 938 (90.9%) had a mental ability test score recorded. The mean score of the matched sample was 37.2 (standard deviation [SD] 13.9) out of a possible score of 76. The mean (SD) for the boys and girls respectively was 38.3 (14.2) and 35.7 (13.9). This compared with 38.6 (15.7) and 37.2 (14.3) for boys and girls in all of Scotland. Graded relationships were found between mental ability in childhood, and social class and deprivation category of residence in adulthood. Being in a higher social class or in a more affluent deprivation category was associated with higher childhood mental ability scores and the scores reduced with increasing deprivation. Future plans for the matched data include examining associations between childhood mental ability and other childhood and adult risk factors for disease in adulthood, and modelling childhood mental ability, alongside other factors available in the Midspan database, as a risk factor for specific illnesses, admission to hospital and mortality
Evidence for hadronic deconfinement in -p collisions at 1.8 TeV
We have measured deconfined hadronic volumes, fm,
produced by a one dimensional (1D) expansion. These volumes are directly
proportional to the charged particle pseudorapidity densities . The hadronization temperature is (syst)
MeV. Using Bjorken's 1D model,the hadronization energy density is (stat) GeV/fm corresponding to an excitation of (stat) quark-gluon degrees of freedom.Comment: 15 pages, 3 figures, 2 table
Latent class cluster analysis of symptom ratings identifies distinct subgroups within the clinical high risk for psychosis syndrome
© 2017 The clinical-high-risk for psychosis (CHR-P) syndrome is heterogeneous in terms of clinical presentation and outcomes. Identifying more homogenous subtypes of the syndrome may help clarify its etiology and improve the prediction of psychotic illness. This study applied latent class cluster analysis (LCCA) to symptom ratings from the North American Prodrome Longitudinal Studies 1 and 2 (NAPLS 1 and 2). These analyses produced evidence for three to five subgroups within the CHR-P syndrome. Differences in negative and disorganized symptoms distinguished among the subgroups. Subgroup membership was found to predict conversion to psychosis. The authors contrast the methods employed within this study with previous attempts to identify more homogenous subgroups of CHR-P individuals and discuss how these results could be tested in future samples of CHR-P individuals
Disks, Tori, and Cocoons: Emission and Absorption Diagnostics of AGN Environments
One of the most important problems in the study of active galaxies is
understanding the detailed geometry, physics, and evolution of the central
engines and their environments. The leading models involve an accretion disk
and torus structure around a central dense object, thought to be a supermassive
black hole. Gas found in the environment of AGN is associated with different
structures: molecular accretion disks, larger scale atomic tori, ionized and
neutral "cocoons" in which the nuclear regions can be embedded. All of them can
be studied at radio wavelengths by various means. Here, we summarize the work
that has been done to date in the radio band to characterize these structures.
Much has been learned about the central few parsecs of AGN in the last few
decades with contemporary instruments but the picture remains incomplete. In
order to be able to define a more accurate model of this region, significant
advances in sensitivity, spectral and angular resolution, and bandpass
stability are required. The necessary advances will only be provided by the
Square Kilometer Array and we discuss the possibilities that these dramatic
improvements will open for the study of the gas in the central region of AGN.Comment: To appear in "Science with the Square Kilometer Array," eds. C.
Carilli and S. Rawlings, New Astronomy Reviews (Elsevier: Amsterdam); 17
pages, 7 figures (four of them in separate gif/tif files) The full paper with
high resolution images can be downloaded from
http://www.astron.nl/~morganti/Papers/AGNenvironment.ps.g
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