1,793 research outputs found
Sources of nitrogen for winter wheat in organic cropping systems
In organic cropping systems, legumes, cover crops, residue incorporation, and manure application are used to maintain soil fertility, but the contributions of these management practices to soil nitrogen (N) supply remain obscure. We examined potential sources of N for winter wheat (Triticum aestivum L.) in four experimental cropping systems established in 1997 on three soil types. Three of the four systems were under organic management. Topsoil N, depth of the A horizon, and cumulated inputs of N since 1997 were determined at plot level. Labile soil N pools (mineral N, potentially mineralizable N [PMN], microbial biomass N [MBN]) were monitored during two growth periods; at one site, biomass C/N ratios were also determined. Soil for labile N analysis was shielded from N inputs during spring application to isolate cumulated system effects. PMN and MBN were correlated across all sites and rotations (r2=0.72). The MBN corresponded to 46-85, 85-145 and 74-172 kg N ha-1 at the three sites and differed significantly between cropping systems, but MBN could not explain differences in wheat grain N yields. Instead, a multiple linear regression model explained 76 and 82% of the variation in grain N yields in organic cropping systems in 2007 and 2008, showing significant effects of, respectively, topsoil N, depth of A horizon, cumulated inputs of N, and N applied to winter wheat in manure. Thus, soil properties, and past and current management all contributed to winter wheat N supply
Underrapportering som prĂŚmis: Hvordan man kan bruge Landspatientregistret i det lokale trafiksikkerhedsarbejde
Landspatientregisterdata kan med fordel inddrages i det kommunale og regionale forebyggende trafiksikkerhedsarbejde. Landspatientregisterdata er indsamlet i forbindelse med henvendelser i danske skadestuer og ved indlÌggelser pü hospitaler og bidrager med et nuanceret billede af fordelingen af personskader pü lige fod med politiets indberetninger. Desuden vil der typisk vÌre flere skader at arbejde med i Landspatientregistret end i politiets database i den enkelte kommune. Denne artikel giver en kortfattet analyse af data fra hele landet samt Københavns og Vejle Kommuner. Underrapportering er en udfordring og man mü bruge de vÌrktøjer, som er for hünden. Det anbefales, at Landspatientregisterdata og politiets registreringer tolkes samlet for at give det bedst mulige input til det lokale trafiksikkerhedsarbejde
Reducing discards without reducing profit:Free gear choice in a Danish result-based management trial
The 2013 Common Fisheries Policy introduced a landing obligation on a range of species, bringing more focus on the full accountability of all catches. To investigate the potentials and challenges of these paradigm shifts, a 6-months âunrestricted gearâ trial was performed in Denmark in 2015. Twelve trawlers were challenged to test their own solutions to reduce unwanted bycatch and/or choke species, while maintaining profitable. The participating fishers tested different options depending on their fishery and the type of issues they faced individually, and adjusted their test fishery over time through incremental small steps. Nine vessels reduced discard ratio in the test fishery, one showed no difference between test and control fishery, while two vessels displayed an increase in discard ratio. Catch compositions also differed, with fewer âchoke speciesâ occurring in the test fisheries and a more valuable size composition. Ultimately, despite smaller landings in multiple vessels, no vessel showed reduction in value-per-unit-effort (VPUE) and one Baltic vessel significantly increased the VPUE. This trial showed that relaxing technical regulations combined with proper incentives has a potential to provide some flexibility to cope with the landing obligation, where unwanted catches could be reduced to some extent without negative effects on economic viability.</jats:p
Mass and charge transport in micro and nano-fluidic channels
We consider laminar flow of incompressible electrolytes in long, straight
channels driven by pressure and electro-osmosis. We use a Hilbert space
eigenfunction expansion to address the general problem of an arbitrary cross
section and obtain general results in linear-response theory for the mass and
charge transport coefficients which satisfy Onsager relations. In the limit of
non-overlapping Debye layers the transport coefficients are simply expressed in
terms of parameters of the electrolyte as well as the hydraulic radius R=2A/P
with A and P being the cross-sectional area and perimeter, respectively. In
articular, we consider the limits of thin non-overlapping as well as strongly
overlapping Debye layers, respectively, and calculate the corrections to the
hydraulic resistance due to electro-hydrodynamic interactions.Comment: Invited paper presented at the Second International Conference on
Transport Phenomena in Micro and Nanodevices, Il Ciocco Hotel and Conference
Center, Barga, Italy, 11-15 June 2006. Accepted for publication in a special
issue of Nanoscale and Microscale Thermophysical Engineering (Taylor &
Francis
A case study on agreement between self-reported bicycle accidents and hospital and police records
A self-report questionnaire on bicycle accidents was distributed to 6,793 respondents every month for one year (2012/2013). This paper evaluates the agreement between hospital data, police data, and self-reports concerning the number of accidents, as well as the information recorded regarding each accident.
Six hundred and ninety-four accidents were self-reported by 6,793 respondents. In 99 cases, the respondents reported getting medical care at a hospital. Of these self-reported contacts, 74 could be matched to a hospital record, but only 53 of the 74 were registered in the hospital records as traffic accidents. Information on the primary opposite party in the 53 accidents was compared, and moderate agreement was found between self-reports and hospital records (Îş=0.63).
In 23 of the self-reported accidents, it was stated that a police report had been recorded, but only 6 accidents could be located in the police records. The sample size was too small to calculate statistical agreement between police records and self-reports.
These findings are relevant to discuss of the level of underreporting of bicycle accidents in Denmark because they indicate that there could be substantially more accidents than noted in official records. Furthermore, this paper provides insight into methodological issues associated with self-reporting of traffic accidents
A case study on agreement between self-reported bicycle accidents and hospital and police records
A self-report questionnaire on bicycle accidents was distributed to 6,793 respondents every month for one year (2012/2013). This paper evaluates the agreement between hospital data, police data, and self-reports concerning the number of accidents, as well as the information recorded regarding each accident.
Six hundred and ninety-four accidents were self-reported by 6,793 respondents. In 99 cases, the respondents reported getting medical care at a hospital. Of these self-reported contacts, 74 could be matched to a hospital record, but only 53 of the 74 were registered in the hospital records as traffic accidents. Information on the primary opposite party in the 53 accidents was compared, and moderate agreement was found between self-reports and hospital records (Îş=0.63).
In 23 of the self-reported accidents, it was stated that a police report had been recorded, but only 6 accidents could be located in the police records. The sample size was too small to calculate statistical agreement between police records and self-reports.
These findings are relevant to discuss of the level of underreporting of bicycle accidents in Denmark because they indicate that there could be substantially more accidents than noted in official records. Furthermore, this paper provides insight into methodological issues associated with self-reporting of traffic accidents
Quantifying biological nitrogen fixation of different catch crops, and residual effects of roots and tops on nitrogen uptake in barley using in-situ 15N labelling
Background and aims
Contributions of legume-based catch crops (LBCCs) to succeeding cereals may be significant. We quantified biological N fixation (BNF) and residual N effects of contrasting CC tops and roots.
Methods
BNF of three LBCCs (red clover, winter vetch, perennial ryegrass-red clover mixture) was quantified in microplots by 15N labelling. Their residual effects on spring barley were tested against two non-LBCCs (perennial ryegrass, fodder radish) after spring incorporation of CC tops or roots in monoliths.
Results
Total N accumulated in LBCCs was 153â226 kg N haâ1, of which 62â66 % was derived from BNF in tops and 31â46 % in macro-roots (0â18 cm soil). Macro-roots represented 31â50 % of total plant N. LBCCs showed similar capacity for soil N extraction as non-LBCCs. After incorporation of LBCC residues, the dry matter and N yields of spring barley were comparable to the effect of 50 kg N fertilisation haâ1, whereas no extra N uptake was derived from non-LBCCs. The 15N-based N fertiliser values of LBCC tops were 34â47 % against 26â29 % for non-LBCCs.
Conclusions
LBCC roots contributed substantial amounts of N to the system, a source that is usually underestimated. N immobilisation after incorporation of non-LBCCs may hamper the growth of following main crops especially after removing tops
Flux tube delocalization at the deconfinement point
We study the behaviour of the flux tube thickness in the vicinity of the
deconfinement transition. We show, using effective string methods, that in this
regime the square width increases linearly and not logarithmically with the
interquark distance. The amplitude of this linear growth is an increasing
function of the temperature and diverges as the deconfinement transition is
approached from below. These predictions are in good agreement with a set of
simulations performed in the 3d gauge Ising model.Comment: 16 pages, 1 figure. Revised version, with an improved discussion of
the dimensional reduction approach. Accepted for publication in JHE
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