Nuclear Pairing: Surface or Bulk ?

We analyse how the spatial localisation properties of pairing correlations are changing in a major neutron shell of heavy nuclei. It is shown that the radial distribution of the pairing density depends strongly on whether the chemical potential is close to a low or a high angular momentum level and has very little sensitivity to whether the pairing force acts in the surface or in the bulk. The averaged pairing density over one major shell is however rather flat, practically independent of the pairing force. Hartree-Fock-Bogoliubov calculations for the isotopic chain $^{100-132}$Sn are presented for demonstration purposes.Comment: 12 pages, 5 figure

Quantum Dot in 2D Topological Insulator: The Two-channel Kondo Fixed Point

In this work, a quantum dot couples to two helical edge states of a 2D topological insulator through weak tunnelings is studied. We show that if the electron interactions on the edge states are repulsive, with Luttinger liquid parameter $K < 1$, the system flows to a stable two-channel fixed point at low temperatures. This is in contrast to the case of a quantum dot couples to two Luttinger liquid leads. In the latter case, a strong electron-electron repulsion is needed, with $K<1/2$, to reach the two-channel fixed point. This two-channel fixed point is described by a boundary Sine-Gordon Hamiltonian with a $K$ dependent boundary term. The impurity entropy at zero temperature is shown to be $\ln\sqrt{2K}$. The impurity specific heat is $C \propto T^{\frac{2}{K}-2}$ when $2/3 < K < 1$, and $C \propto T$ when $K<2/3$. We also show that the linear conductance across the two helical edges has non-trivial temperature dependence as a result of the renormalization group flow.Comment: 4+\epsilon page

Prediction of nitrogen excretion from data on dairy cows fed a wide range of diets compiled in an intercontinental database: A meta-analysis

Manure nitrogen (N) from cattle contributes to nitrous oxide and ammonia emissions and nitrate leaching. Measurement of manure N outputs on dairy farms is laborious, expensive, and impractical at large scales; therefore, models are needed to predict N excreted in urine and feces. Building robust prediction models requires extensive data from animals under different management systems worldwide. Thus, the study objectives were (1) to collate an international database of N excretion in feces and urine based on individual lactating dairy cow data from different continents; (2) to determine the suitability of key variables for predicting fecal, urinary, and total manure N excretion; and (3) to develop robust and reliable N excretion prediction models based on individual data from lactating dairy cows consuming various diets. A raw data set was created based on 5,483 individual cow observations, with 5,420 fecal N excretion and 3,621 urine N excretion measurements collected from 162 in vivo experiments conducted by 22 research institutes mostly located in Europe (n = 14) and North America (n = 5). A sequential approach was taken in developing models with increasing complexity by incrementally adding variables that had a significant individual effect on fecal, urinary, or total 2manure N excretion. Nitrogen excretion was predicted by fitting linear mixed models including experiment as a random effect. Simple models requiring dry matter intake (DMI) or N intake performed better for predicting fecal N excretion than simple models using diet nutrient composition or milk performance parameters. Simple models based on N intake performed better for urinary and total manure N excretion than those based on DMI, but simple models using milk urea N (MUN) and N intake performed even better for urinary N excretion. The full model predicting fecal N excretion had similar performance to simple models based on DMI but included several independent variables (DMI, diet crude protein content, diet neutral detergent fiber content, milk protein), depending on the location, and had root mean square prediction errors as a fraction of the observed mean values of 19.1% for intercontinental, 19.8% for European, and 17.7% for North American data sets. Complex total manure N excretion models based on N intake and MUN led to prediction errors of about 13.0% to 14.0%, which were comparable to models based on N intake alone. Intercepts and slopes of variables in optimal prediction equations developed on intercontinental, European, and North American bases differed from each other, and therefore region-specific models are preferred to predict N excretion. In conclusion, region-specific models that include information on DMI or N intake and MUN are required for good prediction of fecal, urinary, and total manure N excretion. In absence of intake data, region-specific complex equations using easily and routinely measured variables to predict fecal, urinary, or total manure N excretion may be used, but these equations have lower performance than equations based on intake

Prediction of nitrogen excretion from data on dairy cows fed a wide range of diets compiled in an intercontinental database: a meta-analysis

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Les graines protéagineuses comme alternatives au tourteau de soja pour les vacheslaitières : évaluation comparative par méta-analyses in situ et in vivo des paramètresdigestifs et des performances laitières

International audienceIn order to both inventory the published in situ and in vivo data on the use of raw or treated proteaginous seeds(PS), replacing soybean meal (SBM) in the dairy cow diet, and quantify the effects of the substitution of either SBMby raw or treated PS, or raw PS by treated PS, two databases were designed. These databases compile data onfaba bean, lupin and pea seeds, and the technological treatments studied are either thermal, thermomechanical orchemical (tanning). The effects of the substitutions were determined using Student tests comparing theexperimental vs control groups (GP vs TS or treated vs raw GP). Despite the limited amount of available data andthe diversity of feeding practices as well as technological treatments applied, general trends emerge, in particularfor the variables measured in situ. Proteins of raw PS are systematically more degradable in the rumen and lessdigestible in the intestine than SBM ones. Replacing SBM with raw PS also leads to a reduction in the N milk/Nintake ratio and a decrease in the milk protein content. When technologically treated PS are compared to raw ones,proteins are more protected in the rumen and their digestibility in the intestine is improved. Some “treatment ×seed” combinations lead to a higher N secretion in milk (for example extruded lupin) while others lead to adecrease in the milk fat content (for example toasted/roasted faba bean). Finally, the few data available oncomparisons between SBM and treated PS show that some combinations allow to reach a level of proteinsprotection from PS similar to that of SBM (for example autoclaved pea) and very few differences are observed onthe parameters measured in vivo. This work shows that it is possible to replace SBM with treated PS in dairy cowdiets without significantly altering their zootechnical performance, provided that the appropriate treatmentparameters are applied.Pour inventorier à la fois les données in situ et in vivo publiées sur l’utilisation des graines protéagineuses (GP)crues ou traitées, en replacement du tourteau de soja (TS) dans l’alimentation des vaches laitières, et quantifier leseffets de la substitution du TS par des GP crues ou traitées, ou des GP crues par des GP traitées, deux bases dedonnées ont été construites. Ces bases rassemblent les données concernant les graines de féverole, lupin et pois,et les traitements technologiques appliqués sont de natures thermique, thermomécanique ou chimique (tannage).Les effets des substitutions ont été déterminés grâce à des tests de Student comparant les lots expérimental vstémoin (GP vs TS ou GP traitées vs GP crues). Malgré la quantité limitée de données disponibles et la diversitédes pratiques alimentaires ainsi que des traitements technologiques appliqués, des tendances générales sedégagent, en particulier pour les variables mesurées in situ. Les protéines des GP crues sont systématiquementplus dégradables dans le rumen et moins digestibles dans l’intestin que celles du TS. Le remplacement du TS parune GP crue entraine également une diminution du rapport N lait/N ingéré et une diminution du taux protéique dulait. Lorsque les GP sont traitées technologiquement, les protéines sont moins dégradables dans le rumen et leurdigestibilité intestinale est améliorée. Certaines combinaisons « traitement × graine » entrainent une plus fortesécrétion d’azote dans le lait (par exemple le lupin extrudé) tandis que d’autres conduisent à diminuer le tauxbutyreux du lait (par exemple la féverole toastée/torréfiée). Enfin, les quelques données disponibles pour lacomparaison entre TS et GP traitées montrent que certaines combinaisons permettent d’atteindre un niveau deprotection des protéines des GP similaire à celui du TS (par exemple le pois autoclavé) et que très peu dedifférences sont observées sur les paramètres mesurés in vivo. Cette synthèse montre qu'il est possible deremplacer le TS par des GP traitées dans les rations pour vaches laitières sans altérer significativement leursperformances zootechniques, à condition de choisir les paramètres de traitements adaptés