516 research outputs found
Influence of modelled soil biogenic NO emissions on related trace gases and the atmospheric oxidizing efficiency
The emission of nitric oxide (NO) by soils (SNOx) is an important source of oxides of nitrogen (NO<sub>x</sub>=NO+NO<sub>2</sub>) in the troposphere, with estimates ranging from 4 to 21 Tg of nitrogen per year. Previous studies have examined the influence of SNOx on ozone (O<sub>3</sub>) chemistry. We employ the ECHAM5/MESSy atmospheric chemistry model (EMAC) to go further in the reaction chain and investigate the influence of SNOx on lower tropospheric NO<sub>x</sub>, O<sub>3</sub>, peroxyacetyl nitrate (PAN), nitric acid (HNO<sub>3</sub>), the hydroxyl radical (OH) and the lifetime of methane (&tau;<sub>CH<sub>4</sub></sub>). We show that SNOx is responsible for a significant contribution to the NO<sub>x</sub> mixing ratio in many regions, especially in the tropics. Furthermore, the concentration of OH is substantially increased due to SNOx, resulting in an enhanced oxidizing efficiency of the global troposphere, reflected in a ~10% decrease in &tau;<sub>CH<sub>4</sub></sub> due to soil NO emissions. On the other hand, in some regions SNOx has a negative feedback on the lifetime of NO<sub>x</sub> through O<sub>3</sub> and OH, which results in regional increases in the mixing ratio of NO<sub>x</sub> despite lower total emissions in a simulation without SNOx. In a sensitivity simulation in which we reduce the other surface NO<sub>x</sub> emissions by the same amount as SNOx, we find that they have a much weaker impact on OH and &tau;<sub>CH<sub>4</sub></sub> and do not result in an increase in the NO<sub>x</sub> mixing ratio anywhere
Airborne in-situ measurements of vertical, seasonal and latitudinal distributions of carbon dioxide over Europe
International audienceAirborne in-situ observations of carbon dioxide (CO2) were made during 7 intensive measurement campaigns between November 2001 and April 2003 as part of the SPURT project. Vertical profiles and latitudinal gradients in the upper troposphere/lowermost stratosphere were measured along the western shore of Europe from the subtropics to high northern latitudes during different seasons. In the boundary layer, CO2 exhibits a strong seasonal cycle with the maximum mixing ratios in winter and minimum values in summer, reflecting the strength of CO2 uptake by vegetation. Seasonal variations are strongest in high latitudes and propagate to the free troposphere and lowermost stratosphere, although with reduced amplitude, resulting in increasing CO2 mixing ratios with altitude during the summer. In the lowermost stratosphere, the CO2 seasonal cycle is phase-shifted relative to the free troposphere by approximately 3 months, with highest mixing ratios during the summer
Use of Medicare Benefit Scheme mental health services in young people who experienced self-harm and/or suicidal behaviours: Data from the Young Minds Matter survey
OnlinePublObjectives: To examine healthcare utilisation patterns in a sample of young people with self-reported experiences of self-harm and/or suicidal behaviours. Methods: A national survey examining mental health in a nationally representative sample of young Australians aged 12–17 years, linked to routinely collected healthcare and dispensing data. For respondents that self-reported experience of self-harm, suicidal ideation, suicidal plan and/or suicide attempt, we assessed attendance at a Medicare Benefits Scheme (MBS) subsidised MH service or non-MH general practitioner (GP) attendance at three time periods: 1) ever, 2) in the 12 months prior to completing the survey and 3) after completing the survey until 31 Dec 2015.We also assessed correlates associated with attendance and non-attendance at a MH service. Results: The study included 311 young people. MH services were attended in the 12 months before the survey by 38.3% with attempted suicide, 28.7% with a suicidal plan, 28.9% with suicidal ideation and 29.4% with selfharm. MH treatment administered by a GP was the most common MH service (25%); followed treatment by psychologist (15%) and psychiatrist (5%). Attendance at aMH service was observed highest alongsidemore severe self-reported depression. Conclusions: Potential underutilisation ofMBSMHservices by young people with self-harmand/or suicidal behaviours.Kate M. Chitty, Michael Gifford Sawyer, Gregory Carter, David Lawrenc
Effects of paylean (ractopamine⋅HCl) on finishing pig growth and variation
A total of 336 pigs were used in a 21-day
trial to determine the effect of Paylean (9.0
g/ton Ractopamine·HCl) on finishing pig
growth and variation. Pigs were allotted based on weight so that all pens had the same
initial weight and degree of variation within
the pen. Pigs fed Paylean had greater ADG and better feed efficiency than control-fed
pigs (P<0.05). However, no differences in
pen coefficient of variation were observed
(P>0.70). The results suggest that adding
Paylean to the diet improves finishing pig
growth performance but does not affect
weight variation within the pen
Evaluation of hemicell® on growth performance of late nursery pigs
A total of 276 pigs (initially 21.9 lb) was
used to determine the effects of added Hemicell® on growth performance. Hemicell® is a patented fermentation product of Bacillus lentus. The active ingredient in the fermentation product is β-mannanase. However, other enzymes such as amylase, xylanase, cellulases, and α-galactosidase also are present. It is claimed that Hemicell® degrades β-mannan in feed, thus, removing its effects as an antinutritive factor in swine diets. Dietary treatments
were arranged as a 2 x 3 factorial, with
or without 0.05% Hemicell®, in diets with 3
levels of energy density (1,388, 1,488, 1,588
ME, kcal/lb). The 100 kcal increments were achieved by the addition of wheat bran or soy
oil to a corn-soybean meal based diet. The addition of Hemicell® to the diets, regardless of energy level, did not lead to an improvement in growth performance in these late nursery pigs. Increasing energy density of the diet, however, resulted in an improved ADG and F/G
Reconnection of Colliding Cosmic Strings
For vortex strings in the Abelian Higgs model and D-strings in superstring
theory, both of which can be regarded as cosmic strings, we give analytical
study of reconnection (recombination, inter-commutation) when they collide, by
using effective field theories on the strings. First, for the vortex strings,
via a string sigma model, we verify analytically that the reconnection is
classically inevitable for small collision velocity and small relative angle.
Evolution of the shape of the reconnected strings provides an upper bound on
the collision velocity in order for the reconnection to occur. These analytical
results are in agreement with previous numerical results. On the other hand,
reconnection of the D-strings is not classical but probabilistic. We show that
a quantum calculation of the reconnection probability using a D-string action
reproduces the nonperturbative nature of the worldsheet results by Jackson,
Jones and Polchinski. The difference on the reconnection -- classically
inevitable for the vortex strings while quantum mechanical for the D-strings --
is suggested to originate from the difference between the effective field
theories on the strings.Comment: 29 pages, 14 eps figures, JHEP style; references added, typos
correcte
The UKIDSS Galactic Plane Survey
'The definitive version is available at www.blackwell-synergy.com .' Copyright Blackwell Publishing DOI: 10.1111/j.1365-2966.2008.13924.xThe UKIDSS Galactic Plane Survey (GPS) is one of the five near-infrared Public Legacy Surveys that are being undertaken by the UKIDSS consortium, using the Wide Field Camera on the United Kingdom Infrared TelescopePeer reviewe
Half-BPS cosmic string in N=2 supergravity in the presence of a dilaton
We construct new half-BPS cosmic string solutions in D=4 N=2 supergravity
compatible with a consistent truncation to N=1 supergravity where they describe
D-term cosmic strings. The constant Fayet-Iliopoulos term in the N=1 D-term is
not put in by hand but is geometrically engineered by a gauging in the mother
N=2 supergravity theory. The coupling of the N=2 vector multiplets is
characterized by a cubic prepotential admitting an axion-dilaton field, a
common property of many compactifications of string theory. The axion-dilaton
field survives the truncation to N=1 supergravity. On the string configuration
the BPS equations constrain the dilaton to be an arbitrary constant. All the
cosmic string solutions with different values of the dilaton have the same
energy per unit length but different lenght scales.Comment: 52 pages; typos correcte
The Geoengineering Model Intercomparison Project Phase 6 (GeoMIP6): simulation design and preliminary results
International audienceWe present a suite of new climate model experiment designs for the Geoengineering Model Intercompari-son Project (GeoMIP). This set of experiments, named Ge-oMIP6 (to be consistent with the Coupled Model Intercom-parison Project Phase 6), builds on the previous GeoMIP project simulations, and has been expanded to address several further important topics, including key uncertainties in extreme events, the use of geoengineering as part of a portfolio of responses to climate change, and the relatively new idea of cirrus cloud thinning to allow more longwave radiation to escape to space. We discuss experiment designs, as well as the rationale for those designs, showing preliminary results from individual models when available. We also introduce a new feature, called the GeoMIP Testbed, which provides a platform for simulations that will be performed with a few models and subsequently assessed to determine whether the proposed experiment designs will be adopted as core (Tier 1) GeoMIP experiments. This is meant to encourage various stakeholders to propose new targeted experiments that address their key open science questions, with the goal of making GeoMIP more relevant to a broader set of communities
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