267 research outputs found
Two-dimensional incommensurate magnetic fluctuations in Sr(RuTi)O
We investigate the imaginary part of the wave vector dependent dynamic spin
susceptibility in Sr(RuTi)O as a function of
temperature using neutron scattering. At T=5 K, two-dimensional incommensurate
(IC) magnetic fluctuations are clearly observed around
up to approximately 60 meV energy transfer.
We find that the IC excitations disperse to ridges around the
point. Below 50 K, the energy and temperature dependent excitations are well
described by the phenomenological response function for a Fermi liquid system
with a characteristic energy of 4.0(1) meV. Although the wave vector dependence
of the IC magnetic fluctuations in Sr(RuTi)O is
similar to that in the Fermi liquid state of the parent compound,
SrRuO, the magnetic fluctuations are clearly suppressed by the
Ti-doping.Comment: 5 pages, 4 figure
Combining ability patterns among West African pearl millet landraces and prospects for pearl millet hybrid breeding
Pearl millet (Pennisetum glaucum (L.) R. Br.) is an important hybrid crop in India. However, to date limited pearl millet hybrid development has been undertaken in West Africa (WA), which is the center of pearl millet origin and diversity and where this crop is most important outside India. Using a diverse set of WA pearl millet germplasm, objectives of this study were to determine the superiority of population hybrids over open-pollinated varieties for agro-morphological and agronomic traits in WA pearl millet germplasm; and (ii) to derive strategies for pearl millet hybrid breeding in WA, based on quantitative-genetic parameters, combining ability and heterotic patterns among geographically close versus distant pearl millet populations. A 10 × 10 factorial mating design was performed with four parental OPVs from each of five WA countries. The 100 population hybrids and their parents were tested for 14 traits at six locations in one year, thereby using contrasting locations to indirectly sample the rainfall variability inherent to WA pearl millet production environments. Grain yield showed an average panmictic midparent heterosis (PMpH) of 16.7%, ranging from −26 to 73%. The mean grain yield of hybrids based on inter-country crosses did not differ significantly from intra-country crosses. Geographic distance between parents was positively correlated with hybrid grain yield (r = 0.31), but not with PMpH . Some crosses between accessions from Niger/Nigeria and Senegal were outstanding. Predictability of population hybrid performance for grain yield was moderate based on midparent values (r = 0.43) and slightly better based on general combining ability (GCA) (r = 0.56). Overall, pearl millet hybrid breeding in WA seems very promising, but there do not seem to be clear “natural” heterotic groups among WA pearl millet landraces. Such heterotic groups as the basis of sustainable hybrid breeding need rather to be created systematically, by building on existing combining ability patterns and aiming to maximize combining ability between the groups
Agro-morphological Characterization of West and Central African Pearl Millet Accessions
Pearl millet [Pennisetum glaucum (L.) R. Br.] was
domesticated in Sahelian West Africa. This highly
outcrossing crop is one of the most important
staple cereals in the semiarid tropics, adapted to
very harsh rain-fed conditions. Agro-morphological
characterization of local germplasm is very
important to better understand existing diversity,
ease targeted genetic broadening of breeding
populations, and potentially link this knowledge
to genotypic information. The objectives of our
study were to (i) characterize West and Central
African (WCA) pearl millet accessions based on
their agro-morphological traits; (ii) evaluate the
possibility to group accessions based on their
agro-morphological characteristics; (iii) determine
geographic patterns of phenotypic differentiation;
and (iv) derive conclusions for pearl millet
improvement in WCA. A total of 360 early-tomedium
maturity accessions were phenotyped
for 12 agro-morphological traits at six environments
in WCA. Wide ranges of all observed traits
indicated a high diversity of the tested accessions.
Principal component analysis revealed
very large diversity within individual countries,
especially within Mali and Burkina Faso. Some
limited grouping of accessions from Niger, Senegal,
Cameroon, Morocco, and Mauritania was
observed for individual principal component
axes. Geographical differentiation and country
differences were detected for several traits. The
results and data presented in our study reflect
WCA pearl millets’ tremendous diversity and
adaptability to a wide range of environments and
give a sound basis for breeders to select and utilize
this germplasm to serve the manifold needs
of WCA pearl millet farmers
Nominal group consensus process to determine Association of Surgeons in Training quality indicators for integrated clinical academic surgical training across the UK
Built Environmental Correlates of Walking and Cycling in Dutch Urban Children: Results from the SPACE Study
This study examined built environmental correlates of children’s walking and cycling behavior. Four hundred and forty-eight children from 10 Dutch neighborhoods completed a seven-day physical activity diary in which the number of walking and cycling trips for transportation, to school, and for recreation were assessed. The associations between observed built environmental characteristics and children’s walking and cycling behavior were examined with multivariate linear regression analyses. The results showed that built environmental correlates of children’s walking and cycling behavior differ by purpose and by commuting mode implying a behavior-specific approach for interventions and for future, preferably prospective, studies
The impact of cycle proficiency training on cycle-related behaviours and accidents in adolescence: findings from ALSPAC, a UK longitudinal cohort
A multi-modal network approach to model public transport accessibility impacts of bicycle-train integration policies
In the Netherlands, the bicycle plays an important in station access and, to a lesser extent, in station egress. There is however fairly little knowledge in the potential effects of bicycle-train integration policies. The aim of this paper is to examine the impacts of bicycle-train integration policies on train ridership and job accessibility for public transport users.MethodsWe extended the Dutch National Transport Model (NVM) by implementing a detailed bicycle network linked to the public transport network, access/egress mode combinations and station specific access and egress penalties by mode and station type derived from a stated choice survey. Furthermore, the effects of several bicycletrain integration policy scenarios were examined for a case study for Randstad South, in the Netherlands, comprising a dense train network with 54 train stations.ConclusionsOur analysis shows that improving the quality of bicycle routes and parking can substantially increase train ridership and potential job accessibility for train users. Large and medium stations are more sensitive to improvements in bicycle-train integration policies, while small stations are more sensitive to improvements in the train level of service
Effects of residence and race on burden of travel for care: cross sectional analysis of the 2001 US National Household Travel Survey
BACKGROUND: Travel burden is a key element in conceptualizing geographic access to health care. Prior research has shown that both rural and minority populations bear disproportionate travel burdens. However, many studies are limited to specific types of patient or specific locales. The purpose of our study was to quantify geographic and race-based differences in distance traveled and time spent in travel for medical/dental care using representative national data. METHODS: Data were drawn from 2001 National Household Travel Survey (NHTS), a nationally representative, cross-sectional household survey conducted by the US Department of Transportation. Participants recorded all travel on a designated day; the overall response rate was 41%. Analyses were restricted to households reporting at least one trip for medical and/or dental care; 3,914 trips made by 2,432 households. Dependent variables in the analysis were road miles traveled, minutes spent traveling, and high travel burden, defined as more than 30 miles or 30 minutes per trip. Independent variables of interest were rural residence and race. Characteristics of the individual, the trip, and the community were controlled in multivariate analyses. RESULTS: The average trip for care in the US in 2001 entailed 10.2 road miles (16.4 kilometers) and 22.0 minutes of travel. Rural residents traveled further than urban residents in unadjusted analysis (17.5 versus 8.3 miles; 28.2 versus 13.4 km). Rural trips took 31.4% longer than urban trips (27.2 versus 20.7 minutes). Distance traveled did not vary by race. African Americans spent more time in travel than whites (29.1 versus 20.6 minutes); other minorities did not differ. In adjusted analyses, rural residence (odds ratio, OR, 2.67, 95% confidence interval, CI 1.39 5.1.5) was associated with a trip of 30 road miles or more; rural residence (OR, 1.80, CI 1.09 2.99) and African American race/ethnicity (OR 3.04. 95% CI 2.0 4.62) were associated with a trip lasting 30 minutes or longer. CONCLUSION: Rural residents and African Americans experience higher travel burdens than urban residents or whites when seeking medical/dental care
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