Benthic biomass size spectra in shelf and deep-sea sediments

The biomass distributions of marine benthic metazoans (meio- to macro-fauna, 1 ?g–32 mg wet weight) across three contrasting sites were investigated to test the hypothesis that allometry can consistently explain observed trends in biomass spectra. Biomass (and abundance) size spectra were determined from observations made at the Faroe–Shetland Channel (FSC) in the Northeast Atlantic (water depth 1600 m), the Fladen Ground (FG) in the North Sea (150 m), and the hypoxic Oman Margin (OM) in the Arabian Sea (500 m). Observed biomass increased with body size as a power law at FG (scaling exponent, b = 0.16) and FSC (b = 0.32), but less convincingly at OM (b = 0.12 but not significantly different from 0). A simple model was constructed to represent the same 16 metazoan size classes used for the observed spectra, all reliant on a common detrital food pool, and allowing the three key processes of ingestion, respiration and mortality to scale with body size. A micro-genetic algorithm was used to fit the model to observations at the sites. The model accurately reproduces the observed scaling without needing to include the effects of local influences such as hypoxia. Our results suggest that the size-scaling of mortality and ingestion are dominant factors determining the distribution of biomass across the meio- to macrofaunal size range in contrasting marine sediment communities. Both the observations and the model results are broadly in agreement with the "metabolic theory of ecology" in predicting a quarter power scaling of biomass across geometric body size classes

Synthesis of Ligand free CdS Nanoparticles within a Sulfur Copolymer Matrix

Aliphatic ligands are typically used during the synthesis of nanoparticles to help mediate their growth in addition to operating as high temperature solvents. These coordinating ligands help solubilize and stabilize the nanoparticles while in solution, and can influence the resulting size and reactivity of the nanoparticles during their formation. Despite the ubiquity of using ligands during synthesis, the presence of aliphatic ligands on the nanoparticle surface can result in a number of problems during the end use of the nanoparticles, necessitating further ligand stripping or ligand exchange procedures. We have developed a way to synthesize cadmium sulfide CdS nanoparticles using a unique sulfur copolymer. This sulfur copolymer is primarily composed of elemental sulfur, which is a cheap and abundant material. The sulfur copolymer has the advantages of operating both as a high temperature solvent and as a sulfur source, which can react with a cadmium precursor during nanoparticle synthesis, resulting in the generation of ligand free CdS. During the reaction, only some of the copolymer is consumed to produce CdS, while the rest remains in the polymeric state, thereby producing a nanocomposite material. Once the reaction is finished, the copolymer stabilizes the nanoparticles within a solid polymeric matrix. The copolymer can then be removed before the nanoparticles are used, which produces nanoparticles that do not have organic coordinating ligands. This nascent synthesis technique presents a method to produce metal sulfide nanoparticles for a wide variety of applications where the presence of organic ligands is not desired

Toward a Functional Definition of a “Rare Disease” for Regulatory Authorities and Funding Agencies

AbstractBackgroundThe designation of a disease as “rare” is associated with some substantial benefits for companies involved in new drug development, including expedited review by regulatory authorities and relaxed criteria for reimbursement. How “rare disease” is defined therefore has major financial implications, both for pharmaceutical companies and for insurers or public drug reimbursement programs. All existing definitions are based, somewhat arbitrarily, on disease incidence or prevalence.ObjectivesWhat is proposed here is a functional definition of rare based on an assessment of the feasibility of measuring the efficacy of a new treatment in conventional randomized controlled trials, to inform regulatory authorities and funding agencies charged with assessing new therapies being considered for public funding.MethodsIt involves a five-step process, involving significant negotiations between patient advocacy groups, pharmaceutical companies, physicians, and public drug reimbursement programs, designed to establish the feasibility of carrying out a randomized controlled trial with sufficient statistical power to show a clinically significant treatment effect.Results and ConclusionsThe steps are as follows: 1) identification of a specific disease, including appropriate genetic definition; 2) identification of clinically relevant outcomes to evaluate efficacy; 3) establishment of the inherent variability of measurements of clinically relevant outcomes; 4) calculation of the sample size required to assess the efficacy of a new treatment with acceptable statistical power; and 5) estimation of the difficulty of recruiting an adequate sample size given the estimated prevalence or incidence of the disorder in the population and the inclusion criteria to be used

Constraining the nuclear equation of state at subsaturation densities

Only one third of the nucleons in $^{208}$Pb occupy the saturation density area. Consequently nuclear observables related to average properties of nuclei, such as masses or radii, constrain the equation of state (EOS) not at saturation density but rather around the so-called crossing density, localised close to the mean value of the density of nuclei: $\rho\simeq$0.11 fm$^{-3}$. This provides an explanation for the empirical fact that several EOS quantities calculated with various functionals cross at a density significantly lower than the saturation one. The third derivative M of the energy at the crossing density is constrained by the giant monopole resonance (GMR) measurements in an isotopic chain rather than the incompressibility at saturation density. The GMR measurements provide M=1110 $\pm$ 70 MeV (6% uncertainty), whose extrapolation gives K$_\infty$=230 $\pm$ 40 MeV (17% uncertainty).Comment: 4 pages, 4 figure

Quantifying carbon fluxes from primary production to mesopelagic fish using a simple food web model

An ecosystem-based flow analysis model was used to study carbon transfer from primary production (PP) to mesopelagic fish via three groups of copepods: detritivores that access sinking particles, vertical migrators, and species that reside in the surface ocean. The model was parameterized for 40°S to 40°N in the world ocean such that results can be compared with recent estimates of mesopelagic fish biomass in this latitudinal range, based on field studies using acoustic technologies, of ∼13 Gt (wet weight). Mesopelagic fish production was predicted to be 0.32% of PP which, assuming fish longevity of 1.5 years, gives rise to predicted mesopelagic fish biomass of 2.4 Gt. Model ensembles were run to analyse the uncertainty of this estimate, with results showing predicted biomass >10 Gt in only 8% of the simulations. The work emphasizes the importance of migrating animals in transferring carbon from the surface ocean to the mesopelagic zone. It also highlights how little is known about the physiological ecology of mesopelagic fish, trophic pathways within the mesopelagic food web, and how these link to PP in the surface ocean. A deeper understanding of these interacting factors is required before the potential for utilizing mesopelagic fish as a harvestable resource can be robustly assessed

The continuing saga of Sakurai's object (V4334 Sgr): dust production and helium line emission

We report further UKIRT spectroscopic observations of Sakurai's object (V4334 Sgr) made in 1999 April/May in the 1-4.75 µm range, and find that the emission is dominated by amorphous carbon at T[subscript d] ~ 600. The estimated maximum grain size is 0.6 µm, and the mass lower limit is 1.7 ± 0.2 x 10[superscript -8] M[subscript ¤] to 8.9 ± 0.6 x 10[superscript -7] M[subscript ¤] for distances of 1.1-8 kpc. For 3.8 kpc the mass is 2.0 ± 0.1 x 10[superscript -7] M[subscript ¤]. We also report strong He i emission at 1.083 µm, in contrast to the strong absorption in this line in 1998. We conclude that the excitation is collisional, and is probably caused by a wind, consistent with the P Cygni profile observed by Eyres et al. in 1998

Strategic Time Slot Management: A Priori Routing for Online Grocery Retailing

Time slot management refers to the design and control of the delivery time slots offered to customers during the online ordering process. Strategic time slot management is an innovative variant in which only a single time slot is offered each day of the week and a priori delivery routes are used to guide time slot availability. Strategic time slot management simplifies time slot control and fulfillment center operations. We propose a 2-stage stochastic programming formulation for the design of a priori delivery routes and time slot assignments and a sample average approximation algorithm for its solution. An efficient dynamic program is developed for calculating the expected revenue of an a priori route. An extensive computational study demonstrate the efficacy of the proposed approach and provides insights in to the benefits of strategic time slot management

Strategic Time Slot Management: A Priori Routing for Online Grocery Retailing

Time slot management refers to the design and control of the delivery time slots offered to customers during the online ordering process. Strategic time slot management is an innovative variant in which only a single time slot is offered each day of the week and a priori delivery routes are used to guide time slot availability. Strategic time slot management simplifies time slot control and fulfillment center operations. We propose a 2-stage stochastic programming formulation for the design of a priori delivery routes and time slot assignments and a sample average approximation algorithm for its solution. An efficient dynamic program is developed for calculating the expected revenue of an a priori route. An extensive computational study demonstrate the efficacy of the proposed approach and provides insights in to the benefits of strategic time slot management

Phylogenetic relationships among species of Ganoderma (Ganodermataceae, Basigiomycota) from Cameroon

Ganoderma is an important genus of the Polyporales in the tropics. Identification of tropical species has mainly been based on morphology, which has led to misidentification. This study aimed to elucidate the diversity and phylogenetic relationships of Ganoderma isolates from different hosts in Cameroon using morphological and molecular techniques. Analyses of basidiocarp morphology and the internal transcribed spacer and mitochondria small subunit were undertaken for 28 isolates from five plant species. The results show that the isolates belong to eight species. Three of the species were identified to species level; of these only G. ryvardense has been previously described from Cameroon while G. cupreum and G. weberianum are new records. The five remaining species did not match with any previously described species and have been designated as Ganoderma with different species affinities.Laboratory work for this research was funded by the Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, South Africa under the Tree Protection Co-operative Program (TPCP) and Centre for Excellence in Tree Health Biotechnology (CTHB). Fieldwork and equipment were sponsored by the Rufford Small Grant for Nature Conservation and Idea Wild Grant.http://www.publish.csiro.au/nid/65.htmhb2017Forestry and Agricultural Biotechnology Institute (FABI)Genetic

Hydrodynamics of Spatially Ordered Superfluids

We derive the hydrodynamic equations for the supersolid and superhexatic phases of a neutral two-dimensional Bose fluid. We find, assuming that the normal part of the fluid is clamped to an underlying substrate, that both phases can sustain third-sound modes and that in the supersolid phase there are additional modes due to the superfluid motion of point defects (vacancies and interstitials).Comment: 24 pages of ReVTeX and 7 uuencoded figures. Submitted for publication in Phys. Rev.