Ten Simple Rules for Searching and Organizing the Scientific Literature

The exponentially increasing number of published papers (1.4 million per year by one estimate) makes it more and more difficult for us to manage the flood of scientific information. Each of us has acquired some protocol to find and organize journal articles and other references over the course of our careers. Most of those protocols are likely to have been formed by old routines or idleness rather than a structured approach to save time and frustration over the long run. Furthermore, with the Web 2.0 revolution, new ways of handling information are emerging (O’Reilly 2005). For example, traditional standalone tools for reference management like EndNote are being supplemented by centralized resources like RefWorks and social bookmarking sites as described subsequently. This fusion of personal and public information offers the promise of efficiency through better organization, which in turn leads to better science.

How can seasoned scientists do better using these tools and those newer to the field start off in the right way? To start to answer that question, I present ten simple rules to master the search and organization of new literature. This is not meant to be comprehensive. It represents the experiences of a few and I welcome your thoughts, through comments to this article, on what you do to keep your references organized.

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Ultrafast dynamics of finite Hubbard clusters - a stochastic mean-field approach

Finite lattice models are a prototype for strongly correlated quantum systems and capture essential properties of condensed matter systems. With the dramatic progress in ultracold atoms in optical lattices, finite fermionic Hubbard systems have become directly accessible in experiments, including their ultrafast dynamics far from equilibrium. Here, we present a theoretical approach that is able to treat these dynamics in any dimension and fully includes inhomogeneity effects. The method consists in stochastic sampling of mean-field trajectories and is found to be more accurate and efficient than current nonequilibrium Green functions approaches. This is demonstrated for Hubbard clusters with up to 512 particles in one, two and three dimensions

Effect of body temperature of heavy broiler breeders on resistance to heat of their progeny

This trial aimed at studying the effects of the body temperature (BT) of heavy broiler breeders (HBB) on the productive parameters and the resistance to heat of the broilers of their progeny. The experiment was done on two phases: (1) measurements on breeders were done in the commercial hatchery, whereas (2) the tests on broilers were done in the poultry unit of UCV. In phase 1, 280 HBB of line L1 (Ross x Ross) and 280 HBB of line L2 (Hybro) were tested for their rectal body temperature (BT) and level of hyperventilation (LH) during periods of high ambient temperature. The animals were split into two groups: higher BT (HBT, 41.26±0.01°C) and lower BT (LBT, 40.9±0.08°C). Egg production, fertility and hatchability were recorded. A total of 400 chicks (100 of lower of higher parent BT for both lines) were raised in same environmental conditions, and tested for BT, LH and productive parameters. Egg production did not differ between breeders HBT or LBT. Fertility was significantly higher in L2 (98.5±0.08) than in L1 (96.02±0.61). In phase 2 weight gain, feed intake and feed conversion did not differ between animals issued from lower or higher BT parents. At day 36 during a heat challenge (TA=37°C), the BT of animals from L2 issued from parents of higher BT was higher (43.2±0.092 vs 42.7 ± 0.08, p<0.01) whereas this difference was not significant in line L1. Mortality during heat challenge was also 40% higher for these animals. These results suggest than there can be a heritability of BT characteristics, which could have an effect on the resistance of broilers to heat stress. (Résumé d'auteur

From bare interactions, low--energy constants and unitary gas to nuclear density functionals without free parameters: application to neutron matter

We further progress along the line of Ref. [Phys. Rev. {\bf A 94}, 043614 (2016)] where a functional for Fermi systems with anomalously large $s$-wave scattering length $a_s$ was proposed that has no free parameters. The functional is designed to correctly reproduce the unitary limit in Fermi gases together with the leading-order contributions in the s- and p-wave channels at low density. The functional is shown to be predictive up to densities $\sim0.01$ fm$^{-3}$ that is much higher densities compared to the Lee-Yang functional, valid for $\rho < 10^{-6}$ fm$^{-3}$. The form of the functional retained in this work is further motivated. It is shown that the new functional corresponds to an expansion of the energy in $(a_s k_F)$ and $(r_e k_F)$ to all orders, where $r_e$ is the effective range and $k_F$ is the Fermi momentum. One conclusion from the present work is that, except in the extremely low--density regime, nuclear systems can be treated perturbatively in $-(a_s k_F)^{-1}$ with respect to the unitary limit. Starting from the functional, we introduce density--dependent scales and show that scales associated to the bare interaction are strongly renormalized by medium effects. As a consequence, some of the scales at play around saturation are dominated by the unitary gas properties and not directly to low-energy constants. For instance, we show that the scale in the s-wave channel around saturation is proportional to the so-called Bertsch parameter $\xi_0$ and becomes independent of $a_s$. We also point out that these scales are of the same order of magnitude than those empirically obtained in the Skyrme energy density functional. We finally propose a slight modification of the functional such that it becomes accurate up to the saturation density $\rho\simeq 0.16$ fm$^{-3}$

Characterisation of dairy soiled water in a survey of 60 Irish dairy farms

peer-reviewedDairy farming in Ireland generates an effluent known as dairy soiled water (DSW), which consists of a relatively dilute mixture of cow faeces, urine, spilt milk and detergents that is typically applied to grassland. However, relatively little is known about the volumes generated, nutrient content and management factors that influence volume and concentration. Sixty dairy farms that had a separate storage tank for storing DSW were selected for this study. The spatial distribution of the farms reflected the spatial distribution of dairy cows across the 26 counties of the Republic of Ireland, with each farm representing between 10,000 and 20,000 dairy cows. Samples were analysed for biochemical oxygen demand (BOD), ammonium N (NH4-N), total nitrogen (TN), potassium (K), phosphorus (molybdate-reactive and total) (MRP and TP) and dry matter (DM) content. Management characteristics and parlour properties were quantified. Factors influencing volume and concentration of DSW were determined using mixed model multiple regression analysis. On average, 9784 l (standard error 209 l) of DSW, including rainfall, was produced cow−1 year−1 and this contained significant quantities of total N, P and K (587, 80 and 568 mg l−1, respectively). A typical Irish dairy farm stocked at 1.9 cows ha−1 could therefore supply approximately 13, 2 and 12 kg ha−1 of total N, P and K, respectively, across the farm, annually to meet some of the nutrient requirements for herbage production and potentially replace some of the synthetic fertilizer use. Seventy one percent of samples were within the regulated concentration limits of soiled water for BOD (<2500 mg l−1), rising to 87% during the closed period for slurry spreading (mid October to mid-late January), while 81% were within the concentration limits for DM (<1% DM), rising to 94% during the closed period. The efficiency of a milking parlour (cows per unit, time taken) plays a key role in determining the volume of DSW generated. This, in turn, also influences the concentration of nutrients and other chemicals. Large variability was found in nutrient concentrations and this presents a challenge for effective nutrient management to maximise the fertilizer replacement value of DSW

Berry phase in graphene: a semiclassical perspective

We derive a semiclassical expression for the Green's function in graphene, in which the presence of a semiclassical phase is made apparent. The relationship between this semiclassical phase and the adiabatic Berry phase, usually referred to in this context, is discussed. These phases coincide for the perfectly linear Dirac dispersion relation. They differ however when a gap is opened at the Dirac point. We furthermore present several applications of our semiclassical formalism. In particular we provide, for various configurations, a semiclassical derivation of the electron's Landau levels, illustrating the role of the semiclassical ``Berry-like'' phas

Production function approach to calculating potential growth and output gaps - estimates for the EU Member States and the US

This paper describes the methodology for calculating potential growth and output gaps using a production function approach. On the basis of the Commission services Spring 2002 economic forecasts, the approach is illustrated by providing estimates for the EU's Member States, the Euro Zone and EU15 aggregates as well as for the United States.production function, growth and output, economic forecasts, Denis, Mc Morrow, R�ger