4,567 research outputs found
Determination of a Wave Function Functional
In this paper we propose the idea of expanding the space of variations in
standard variational calculations for the energy by considering the wave
function to be a functional of a set of functions , rather than a function. In this manner a greater flexibility to
the structure of the wave function is achieved. A constrained search in a
subspace over all functions such that the wave function functional
satisfies a constraint such as normalization or the Fermi-Coulomb
hole charge sum rule, or the requirement that it lead to a physical observable
such as the density, diamagnetic susceptibility, etc. is then performed. A
rigorous upper bound to the energy is subsequently obtained by variational
minimization with respect to the parameters in the approximate wave function
functional. Hence, the terminology, the constrained-search variational method.
The \emph{rigorous} construction of such a constrained-search--variational wave
function functional is demonstrated by example of the ground state of the
Helium atom.Comment: 10 pages, 2 figures, changes made, references adde
OcorrĂȘncia dos agentes etiolĂłgicos causadores de mastite subclĂnica em ovelhas das raças Morada Nova e Santa InĂȘs .
Phosphatic nutrition affects biomass production, photosynthetic pigment concentration and artemisinin biosynthesis in A. annua plants grown in presence or not of F. mosseae
OcorrĂȘncia dos agentes etiolĂłgicos causadores de mastite subclĂnica em ovelhas das Raças Morada Nova e Santa InĂȘs.
This study aimed to determine the occurrence of the etiologic agents of subclinical mastitis in Santa InĂȘs and Morada Nova ewes and their susceptibility to developing the disease when submitted to the same management conditions. We analyzed 250 mammary glands of 130 Santa InĂȘs ewes and 143 mammary glands of 77 Morada Nova ewes. The California Mastitis Test, somatic cell counts and microbiological analysis were performed at the moment of drying off. The occurrences of subclinical mastitis in different breeds were analyzed using the chi-square test by adjusting the values according to the Yates continuity correction. The infectious subclinical mastitis was present in 33.1% and 35.1% of Santa InĂȘs and Morada Nova ewes, respectively. Among the evaluated mammary glands of Santa InĂȘs ewes, 20.4% had subclinical mastitis with the following infectious etiology: Coagulase-negative Staphylococci (CNS) (46%), Coliforms (22.0%), Streptococcus spp. (12.0%), Corynebacterium spp. (6%), Micrococcus spp. (6.0%), Staphylococcus aureus (2.0%), Coagulase-positive Staphylococci (2.0%) and CNS and Streptococcus spp. (4.0%) mixed infection. Of the Morada Nova ewe mammary glands evaluated, 21% had subclinical mastitis with the following etiologic agents and their occurrences: CNS (56.7%), Coliforms (13.3%), Corynebacterium spp. (10.0%), Staphylococcus aureus (10.0%), Micrococcus spp. (6.7%) and Streptococcus spp. (3.3%). The CNS can be considered the most important etiological agent of subclinical mastitis in sheep. Santa InĂȘs and Morada Nova ewes have the same chances of developing sub-clinical mastitis when subjected to the same management system
Impact of Phosphatic Nutrition on Growth Parameters and Artemisinin Production in Artemisia annua Plants Inoculated or Not with Funneliformis mosseae
Artemisia annua L. is a medicinal plant appreciated for the production of artemisinin, a molecule used for malaria treatment. However, the natural concentration of artemisinin in planta is low. Plant nutrition, in particular phosphorus, and arbuscular mycorrhizal (AM) fungi can affect both plant biomass and secondary metabolite production. In this work, A. annua plants were inoculated or not with the AM fungus Funneliformis mosseae BEG12 and cultivated for 2 months in controlled conditions at three different phosphatic (P) concentrations (32, 96, and 288 ”M). Plant growth parameters, leaf photosynthetic pigment concentrations, artemisinin production, and mineral uptake were evaluated. The different P levels significantly affected the plant shoot growth, AM fungal colonization, and mineral acquisition. High P levels negatively influenced mycorrhizal colonization. The artemisinin concentration was inversely correlated to the P level in the substrate. The fungus mainly affected root growth and nutrient uptake and significantly lowered leaf artemisinin concentration. In conclusion, P nutrition can influence plant biomass production and the lowest phosphate level led to the highest artemisinin concentration, irrespective of the plant mineral uptake. Plant responses to AM fungi can be modulated by costâbenefit ratios of the mutualistic exchange between the partners and soil nutrient availability
Impact of Holocene climate variability on lacustrine records and human settlements in South Greenland
International audienceDue to its sensitivity to climate changes, south Greenland is a particularly suitable area to study past global climate changes and their influence on locale Human settlements. A paleohydrological investigation was therefore carried out on two river-fed lakes: Lake Qallimiut and Little Kangerluluup, both located close to the Labrador Sea in the historic 5 farming center of Greenland. Two sediment cores (QAL-2011 and LKG-2011), spanning the last four millennia, were retrieved and showed similar thin laminae, described by high magnetic susceptibility and density, high titanium and TOC / TN atomic ratio, and coarse grain size. They are also characterized either by inverse grading followed by normal grading or by normal grading only and a prevalence of red amorphous particles 10 and lignocellulosic fragments, typical of flood deposits. Flood events showed similar trend in both records: they mainly occurred during cooler and wetter periods characterized by weaker Greenlandic paleo-temperatures, substantial glacier advances, and a high precipitation on the Greenlandic Ice Sheet and North Atlantic ice-rafting events. They can therefore be interpreted as a result of ice and 15 snow-melting episodes. They occurred especially during rapid climate changes (RCC) such as the Middle to Late Holocene transition around 2250 BC, the Sub-boreal/Sub-atlantic transition around 700 BC and the Little Ice Age (LIA) between AD 1300 and AD 1900, separated by cycles of 1500 years and driven by solar forcing. These global RCC revealed by QAL-2011 and LKG-2011 flood events may have influenced Human 20 settlements in south Greenland, especially the paleo-Eskimo cultures and the Norse settlement, and have been mainly responsible for their demise
Antenatal Microbial Colonization of Mammalian Gut
The widely accepted dogma of intrauterine sterility and initial colonization of the newborn during birth has been blurred by recent observations of microbial presence in meconium, placenta, and amniotic fluid. Given the importance of a maternal-derived in utero infant seeding, it is crucial to exclude potential environmental or procedural contaminations and to assess fetal colonization before parturition. To this end, we analyzed sterilely collected intestinal tissues, placenta, and amniotic fluid from rodent fetuses and tissues from autoptic human fetuses. Total bacterial DNA was extracted from collected samples and analyzed by Next Generation Sequencing (NGS) techniques using hypervariable 16S ribosomal RNA (rRNA) regions (V3-V4). Colonizing microbes were visualized in situ, using labeled probes targeting 16S ribosomal DNA by fluorescent in situ hybridization. The NGS analysis showed the presence of pioneer microbes in both rat and human intestines as well as in rodent placentas and amniotic fluids. Microbial communities showed fetus- and dam-dependent clustering, confirming the high interindividual variability of commensal microbiota even in the antenatal period. Fluorescent in situ hybridization analysis confirmed the microbes' presence in the lumen of the developing gut. These findings suggest a possible antenatal colonization of the developing mammalian gut
A study of the deep structure of the energy landscape of glassy polystyrene: the exponential distribution of the energy-barriers revealed by high-field Electron Spin Resonance spectroscopy
The reorientation of one small paramagnetic molecule (spin probe) in glassy
polystyrene (PS) is studied by high-field Electron Spin Resonance spectroscopy
at two different Larmor frequencies (190 and 285 GHz). The exponential
distribution of the energy-barriers for the rotational motion of the spin probe
is unambigously evidenced at both 240K and 270K. The same shape for the
distribution of the energy-barriers of PS was evidenced by the master curves
provided by previous mechanical and light scattering studies. The breadth of
the energy-barriers distribution of the spin probe is in the range of the
estimates of the breadth of the PS energy-barriers distribution. The evidence
that the deep structure of the energy landscape of PS exhibits the exponential
shape of the energy-barriers distribution agrees with results from
extreme-value statistics and the trap model by Bouchaud and coworkers.Comment: Final version in press as Letter to the Editor on J.Phys.:Condensed
Matter. Changes in bol
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