Weak Localization Coexisting with a Magnetic Field in a Normal-Metal--Superconductor Microbridge

A random-matrix theory is presented which shows that breaking time-reversal symmetry by itself does {\em not} suppress the weak-localization correction to the conductance of a disordered metal wire attached to a superconductor. Suppression of weak localization requires applying a magnetic field as well as raising the voltage, to break both time-reversal symmetry and electron-hole degeneracy. A magnetic-field dependent contact resistance obscured this anomaly in previous numerical simulations.Comment: 8 pages, REVTeX-3.0, 1 figur

Limiting nutrients for bean production on contrasting soil types of Lake Victoria Crescent of Uganda

Common bean (Phaseolus vulgaris L.) is one of the most important grain legumes in East Africa, but its yield has remained below the genetic potential. Declining soil fertility is among the primary constraints to bean production in most East African bean producing regions. Often existing recommendations are generic and inept to guide farm level decision making on nutrient replenishment. A greenhouse nutrient omission study was conducted to determine the limiting nutrients in three soils of Masaka District, commonly cropped to beans: “Liddugavu” a Phaeozem, “Limyufumyufu” a Cambisol and “Luyinjayinga” an Umbrisol soil. Nine treatments; (i) complete nutrient treatment, (ii) N omitted, (iii) P omitted, (iv) K omitted, (v) Mg omitted, (vi) S omitted, (vii) Ca omitted, (viii) Micronutrients omitted and (ix) control without nutrients. Each treatment was randomly assigned to the three soils and replicated three times using a completely randomised design. Nitrogen, phosphorus and potassium were limiting nutrients for bean production in Umbrisol (Luyinjayinja) while in Cambisol (‘Limyufumyufu), common bean production was most limited by soil acidity. The performance varied with soil types, with beans grown on the Phaeozem registering greater leaf number and growth, confirming both scientist’s and local farmer’s knowledge that this soil has greater potential than the other two soils

Adiabatic Dynamics of Superconducting Quantum Point Contacts

Starting from the quasiclassical equations for non-equilibrium Green's functions we derive a simple kinetic equation that governs ac Josephson effect in a superconducting quantum point contact at small bias voltages. In contrast to existing approaches the kinetic equation is valid for voltages with arbitrary time dependence. We use this equation to calculate frequency-dependent linear conductance, and dc $I\!-\!V$ characteristics with and without microwave radiation for resistively shunted quantum point contacts. A novel feature of the $I\!-\!V$ characteristics is the excess current $2I_c/\pi$ appearing at small voltages. An important by-product of our derivation is the analytical proof that the microscopic expression for the current coincides at arbitrary voltages with the expression that follows from the Bogolyubov-de Gennes equations, if one uses appropriate amplitudes of Andreev reflection which contain information about microscopic structure of the superconductors.Comment: 12 Pages, REVTEX 3.0, 3 figures available upon reques

Limiting nutrients for bean production on contrasting soil types of Lake Victoria Crescent of Uganda

Common bean (Phaseolus vulgaris L.) is one of the most important grain legumes in East Africa, but its yield has remained below the genetic potential. Declining soil fertility is among the primary constraints to bean production in most East African bean producing regions. Often existing recommendations are generic and inept to guide farm level decision making on nutrient replenishment. A greenhouse nutrient omission study was conducted to determine the limiting nutrients in three soils of Masaka District, commonly cropped to beans: \u201cLiddugavu\u201d a Phaeozem, \u201cLimyufumyufu\u201d a Cambisol and \u201cLuyinjayinga\u201d an Umbrisol soil. Nine treatments; (i) complete nutrient treatment, (ii) N omitted, (iii) P omitted, (iv) K omitted, (v) Mg omitted, (vi) S omitted, (vii) Ca omitted, (viii) Micronutrients omitted and (ix) control without nutrients. Each treatment was randomly assigned to the three soils and replicated three times using a completely randomised design. Nitrogen, phosphorus and potassium were limiting nutrients for bean production in Umbrisol (Luyinjayinja) while in Cambisol (\u2018Limyufumyufu), common bean production was most limited by soil acidity. The performance varied with soil types, with beans grown on the Phaeozem registering greater leaf number and growth, confirming both scientist\u2019s and local farmer\u2019s knowledge that this soil has greater potential than the other two soils.Le haricot commun (Phaseolus vulgaris L.) est un des l\ue9gumes \ue0 grains les plus importants en Afrique de l\u2019Est, mais son rendement reste toujours en dessous de son potentiel g\ue9n\ue9tique. La baisse de la fertilit\ue9 du sol est parmi les contraintes primaires \ue0 la production du haricot dans la plupart des r\ue9gions productrices de l\u2019Afrique de l\u2019Est. Le plus souvent, les recommandations sont g\ue9n\ue9riques et inad\ue9quates pour guider la prise de d\ue9cision au niveau champ sur le r\ue9approvisionnement en nutriment. Une \ue9tude sous serre sur l\u2019omission de nutriment a \ue9t\ue9 conduite pour d\ue9terminer les nutriments limitants dans les trois sols du district de Masaka, commun\ue9ment utilis\ue9s pour produire du haricot\ua0: \u201cLiddugavu\u201d un sol du Phaeozem, \u201cLimyufumyufu\u201d un sol du Cambisol et \u201cLuyinjayinga\u201d un sol du Umbrisol. Neuf traitements, (i) traitement complet de nutriments, (ii) N omis, (iii) P omis, (iv) K omis, (v) Mg omis, (iv) S omis, (vii) Ca omis, (viii) micronutriments omis et (ix) control sans nutriments. Chacun des traitements a \ue9t\ue9 al\ue9atoirement distribu\ue9 aux trois types de sols et r\ue9pliqu\ue9 trois fois dans un dispositif compl\ue8tement al\ue9atoire. Azote, phosphore, et potassium ont \ue9t\ue9 les nutriments limitants pour la production du haricot dans Umbrisol (Luyinjayinja) tandis que dans Cambisol (\u2018Limyufumyufu), la production du haricoct commun a \ue9t\ue9 limit\ue9e par l\u2019acidit\ue9 du sol. Les performances varient en fonction des types de sols, avec le haricot produit sur le Phaeozem comptant plus de feuilles et de croissance, confirmant \ue0 la fois les connaissances des scientifiques et des populations locales qui stipulent que le sol a un potentiel plus \ue9lev\ue9 que les deux autres sols

Plant Dispersal in a Temperate Stream by Fish Species With Contrasting Feeding Habits: The Role of Plant Traits, Fish Diet, Season, and Propagule Availability

Whether fish mediate plant dispersal in temperate freshwaters is largely unknown. A prerequisite for successful dispersal is ingestion and surviving the journey in the intestinal tract. This study asks whether plant propagules are being ingested under field conditions and what factors shape dispersal potential, focusing on differences across plant species and propagule form (seed or fragment), seasonal differences and plant and fish traits that facilitate dispersal. We focused on three common fish species reported to differ in foraging strategy. Fish were caught monthly over a 1-year period in a Dutch lowland stream. Before they were returned to the stream, fish were kept in water for 26 h and their feces were collected, resulting in 150 fecal samples. Excreted animal remains and plant propagules were identified and enumerated. Plant propagules were tested for viability. In total, 88,579 vegetative fragments of vascular plants, 316 of mosses and 14 of charophytes were identified. Viability was low (<<1%) except for mosses (53.5%). Roach (Rutilis rutilis) and Rudd (Scardinius erythrophthalmus) displayed a preference for filamentous algae and certain plant species (i.e., Elodea nuttallii and Lemna sp.), likely because they were more palatable. Of the 1,787 generative propagules of vascular plants that were identified, 120 germinated (6.7%), representing 15 species. Betula pendula, Juncus effusus, and Poa trivialis were most abundant. Tench (Tinca tinca) egested most seeds, despite being the least herbivorous species. Particularly, germination was high for seeds that were light (<1.07 mg) and that floated for a long time. Our results show that fish do ingest plant propagules under field conditions and that fish can contribute to vegetative dispersal of vascular plants and several aquatic and riparian moss species. Ingestion of propagules is affected by water temperature and season, their availability in the propagule bank, and their palatability. Both seed traits (related to buoyancy, size and hardness) and fish traits (related to size and identity) were important. Despite substantial dietary overlap, the three fish species displayed subtle differences in their diet, and together can act as vectors for the dispersal of a range of plant and moss species of freshwater systems

Exercise capacity, muscle strength and fatigue in sarcoidosis

ABSTRACT: The aim of this case-control study was to investigate the prevalence of exercise intolerance, muscle weakness and fatigue in sarcoidosis patients. Additionally, we evaluated whether fatigue can be explained by exercise capacity, muscle strength or other clinical characteristics (lung function tests, radiographic stages, prednisone usage and inflammatory markers). 124 sarcoidosis patients (80 males) referred to the Maastricht University Medical Centre (Maastricht, the Netherlands) were included (mean age 46.6¡10.2 yrs). Patients performed a 6-min walk test (6MWT) and handgrip force (HGF), elbow flexor muscle strength (EFMS), quadriceps peak torque (QPT) and hamstring peak torque (HPT) tests. Maximal inspiratory pressure (PI,max) was recorded. All patients completed the Fatigue Assessment Scale (FAS) questionnaire. The 6MWT was reduced in 45% of the population, while HGF, EFMS, QPT and HPT muscle strength were reduced in 15, 12, 27 and 18%, respectively. PI,max was reduced in 43% of the population. The majority of the patients (81%) reported fatigue (FAS o22). Patients with reduced peripheral muscle strength of the upper and/or lower extremities were more fatigued and demonstrated impaired lung functions, fat-free mass, PI,max, 6MWT and quality of life. Fatigue was neither predicted by exercise capacity, nor by muscle strength. Besides fatigue, exercise intolerance and muscle weakness are frequent problems in sarcoidosis. We therefore recommend physical tests in the multidisciplinary management of sarcoidosis patients, even in nonfatigued patients

Additive sustainability footprint: Rationale and pilot evaluation of a tool for assessing the sustainable use of PVC additives

© 2019 The Authors. Journal of Vinyl and Additive Technology published by Wiley Periodicals, Inc. on behalf of Society of Plastics Engineers. PVC compounds contain additives necessary for processing and stability, and to modify the plastic's properties. The Europe-wide VinylPlus® voluntary commitment includes a challenge to make progress toward sustainable use of additives. Additive Sustainability Footprint (ASF) was developed to assess sustainable use of additives across the whole societal life cycles of finished PVC articles, taking a risk-based approach rather than simplistic hazard assessment. ASF addresses impacts across six life cycle assessment (LCA) stages established by ISO Standard 14040, using the four System Conditions (sustainability principles) developed by The Natural Step (TNS) covering social as well as environmental factors. For each LCA stage/System Condition combination, seven generically similar questions cover negative impacts (many covered by existing tools and regulations) but also the additive's positive contributions to the sustainability of finished articles. Positive contributions include ethical sourcing, longevity of service life, low maintenance inputs, and recyclability. Answers to questions determine a score, which can be combined across the life cycle and with other additives. Testing on a generic EU PVC window profile supported ASF development and demonstrated applicability and potential benefits including use for sensitivity analysis of alternative additives from different geopolitical regions or from recycled as opposed to virgin sources. J. VINYL ADDIT. TECHNOL., 2019. © 2019 The Authors. Journal of Vinyl and Additive Technology published by Wiley Periodicals, Inc. on behalf of Society of Plastics Engineers

Dissipative Electron Transport through Andreev Interferometers

We consider the conductance of an Andreev interferometer, i.e., a hybrid structure where a dissipative current flows through a mesoscopic normal (N) sample in contact with two superconducting (S) "mirrors". Giant conductance oscillations are predicted if the superconducting phase difference $\phi$ is varied. Conductance maxima appear when $\phi$ is on odd multiple of $\pi$ due to a bunching at the Fermi energy of quasiparticle energy levels formed by Andreev reflections at the N-S boundaries. For a ballistic normal sample the oscillation amplitude is giant and proportional to the number of open transverse modes. We estimate using both analytical and numerical methods how scattering and mode mixing --- which tend to lift the level degeneracy at the Fermi energy --- effect the giant oscillations. These are shown to survive in a diffusive sample at temperatures much smaller than the Thouless temperature provided there are potential barriers between the sample and the normal electron reservoirs. Our results are in good agreement with previous work on conductance oscillations of diffusive samples, which we propose can be understood in terms of a Feynman path integral description of quasiparticle trajectories.Comment: 24 pages, revtex, 12 figures in eps forma