Front End Electronics for Calorimetry in Space

International audienceA front end read-out electronic system has been developed for the electromagnetic calorimeter (ECAL) of the AMS experiment [1]. AMS will be installed on the International Space Station (ISS) and will record several billions cosmic rays per year of operation. The ECAL frond-end read-out was designed with a dynamic range of 60,000 to measure minimum ionizing particles and high energy (more than 1 TeV) electromagnetic showers as well

Dark matter searches with AMS-02

International audienceThe Alpha Magnetic Spectrometer (AMS), to be installed on ISS, will provide data on cosmic radiations in a large range of energy from 0.5 GeV to 3 TeV. The main physics goals in the astroparticle domain are the anti-matter and the dark matter searches. Observations and cosmology indicate that the Universe may include a large amount of unknown Dark Matter. It should be composed of non baryonic Weakly Interactive Massive Particles (WIMP). A good WIMP candidate being the Lightest Susy Particle in R-Parity conserving models. AMS offers a unique opportunity to study simultaneously SUSY dark matter in three decay channels from the neutralino annihilation: e+, antiproton and gamma. The supersymmetric theory frame is considered together with alternative scenarii (extra dimensions). The expected flux sensitivities in three years exposure for the e + /(e+ + e-) ratio, antiproton and gamma yields as a function of energy are presented

Evaluating detection limits of next-generation sequencing for the surveillance and monitoring of international marine pests

Most surveillance programmes for marine invasive species (MIS) require considerable taxonomic expertise, are laborious, and are unable to identify species at larval or juvenile stages. Therefore, marine pests may go undetected at the initial stages of incursions when population densities are low. In this study, we evaluated the ability of the benchtop GS Junior™ 454 pyrosequencing system to detect the presence of MIS in complex sample matrices. An initial in-silico evaluation of the mitochondrial cytochrome c oxidase subunit I (COI) and the nuclear small subunit ribosomal DNA (SSU) genes, found that multiple primer sets (targeting a ca. 400 base pair region) would be required to obtain species level identification within the COI gene. In contrast a single universal primer set was designed to target the V1–V3 region of SSU, allowing simultaneous PCR amplification of a wide taxonomic range of MIS. To evaluate the limits of detection of this method, artificial contrived communities (10 species from 5 taxonomic groups) were created using varying concentrations of known DNA samples and PCR products. Environmental samples (water and sediment) spiked with one or five 160 hr old Asterias amurensis larvae were also examined. Pyrosequencing was able to recover DNA/PCR products of individual species present at greater than 0.64% abundance from all tested contrived communities. Additionally, single A. amurensis larvae were detected from both water and sediment samples despite the co-occurrence of a large array of environmental eukaryotes, indicating an equivalent sensitivity to quantitative PCR. NGS technology has tremendous potential for the early detection of marine invasive species worldwide

Biogeographic partitioning and host specialization among foraminiferan dinoflagellate symbionts ( Symbiodinium

Large discoidal soritid foraminiferans (Soritinae) are abundant in coral reef ecosystems. As with the many cnidarian invertebrates that inhabit these systems, they also depend on symbiotic dinoflagellates (Symbiodinium) for their growth and survival. Several particular Symbiodinium sub-genera or clades inhabit these soritids. One of these groups, referred to as cladeC, dominates corals and their relatives throughout the tropical Indo-Pacific. In contrast, the distributions of Symbiodinium spp. from cladesA, B, and C are more evenly apportioned across Caribbean invertebrate communities. To explore the possibility that a similar biogeographic break exists in the symbionts harbored by soritids, we surveyed the Symbiodinium spp. from the soritid genus Sorites, collected from the Pacific and Caribbean coasts of Panama as well as from Florida. Characterization of Symbiodinium obtained from foraminiferal and cnidarian samples was conducted using restriction fragment length polymorphism and phylogenetic analyses of the nuclear internal transcribed spacer region2 (ITS2) and a portion of the large subunit ribosomal DNA sequences. A distinctive biogeographic break between the kinds of symbionts found in Sorites from the East Pacific and Caribbean was clearly evident. Differences between cnidarian and foraminferan symbioses in each ocean may be explained by the subjection of Caribbean communities to severer environmental conditions during the early Quarternary. Caribbean Sorites spp. harbored symbionts described from cladeF (specifically sub-cladeFr4) and cladeH (formally referred to as Fr1), while Sorites spp. from the eastern Pacific were dominated by a single Symbiodinium haplotype in cladeC. An ITS2 phylogeny determined that most cladeC "types” recovered from Indo-Pacific soritids form a monophyletic sub-lineage with other cladeC symbionts typically found in Pacific corals from the genus Porites. The existence of multiple Symbiodinium lineages at various taxonomic levels associated specifically with soritids indicates that symbioses with these hosts are important in driving Symbiodinium spp. evolutio

Kaluza-Klein Dark Matter and Galactic Antiprotons

Extra dimensions offer new ways to address long-standing problems in beyond the standard model particle physics. In some classes of extra-dimensional models, the lightest Kaluza-Klein particle is a viable dark matter candidate. In this work, we study indirect detection of Kaluza-Klein dark matter via its annihilation into antiprotons. We use a sophisticated galactic cosmic ray diffusion model whose parameters are fully constrained by an extensive set of experimental data. We discuss how fluxes of cosmic antiprotons can be used to exclude low Kaluza-Klein masses.Comment: 14 pages, 7 figures, 3 table

One-year survey of a single Micronesian reef reveals extraordinarily rich diversity of Symbiodinium types in soritid foraminifera

Recent molecular studies of symbiotic dinoflagellates (genus Symbiodinium) from a wide array of invertebrate hosts have revealed exceptional fine-scale symbiont diversity whose distribution among hosts, regions and environments exhibits significant biogeographic, ecological and evolutionary patterns. Here, similar molecular approaches using the internal transcribed spacer-2 (ITS-2) region were applied to investigate cryptic diversity in Symbiodinium inhabiting soritid foraminifera. Approximately 1,000 soritid specimens were collected and examined during a 12-month period over a 40m depth gradient from a single reef in Guam, Micronesia. Out of 61 ITS-2 types distinguished, 46 were novel. Most types found are specific for soritid hosts, except for three types (C1, C15 and C19) that are common in metazoan hosts. The distribution of these symbionts was compared with the phylotype of their foraminiferal hosts, based on soritid small subunit ribosomal DNA sequences, and three new phylotypes of soritid hosts were identified based on these sequences. Phylogenetic analyses of 645 host-symbiont pairings revealed that most Symbiodinium types associated specifically with a particular foraminiferal host genus or species, and that the genetic diversity of these symbiont types was positively correlated with the genetic diversity found within each of the three host genera. Compared to previous molecular studies of Symbiodinium from other locations worldwide, the diversity reported here is exceptional and suggests that Micronesian coral reefs are home to a remarkably large Symbiodinium assemblag

Physics design of a saddle coil system for TCV

The upgrade project for TCV (Tokamak à Configuration Variable) includes the installation of a set of saddle coils, namely the saddle coil system (SCS), located and powered such as to create a helical magnetic perturbation. Using independent power supplies, the toroidal periodicity of this perturbation is tunable, allowing simultaneously edge localized modes (ELM) control through resonant magnetic perturbation (RMP), error field correction and vertical control. Other experimental applications, like resistive wall mode and rotation control, are also in view. In this article, the adequacy of two SCS designs, an in-vessel one and an ex-vessel one, is assessed with respect to the desired experimental applications. The current requirements and the system performances are also characterized. The conducting vessel wall is accounted for in a model used to determine the coupled response functions of the SCS, the screening of the magnetic perturbation by the wall, the induced voltages and currents during a plasma disruption and the maximal magnetic forces exerted on the SCS. A scaling of the SCS parameters with the number of coil turns is presented and the issue of coil heating and cooling is discussed

Generalist dinoflagellate endosymbionts and host genotype diversity detected from mesophotic (67-100 m depths) coral Leptoseris

<p>Abstract</p> <p>Background</p> <p>Mesophotic corals (light-dependent corals in the deepest half of the photic zone at depths of 30 - 150 m) provide a unique opportunity to study the limits of the interactions between corals and endosymbiotic dinoflagellates in the genus <it>Symbiodinium</it>. We sampled <it>Leptoseris </it>spp. in Hawaii via manned submersibles across a depth range of 67 - 100 m. Both the host and <it>Symbiodinium </it>communities were genotyped, using a non-coding region of the mitochondrial ND5 intron (NAD5) and the nuclear ribosomal internal transcribed spacer region 2 (ITS2), respectively.</p> <p>Results</p> <p>Coral colonies harbored endosymbiotic communities dominated by previously identified shallow water <it>Symbiodinium </it>ITS2 types (C1_ AF333515, C1c_ AY239364, C27_ AY239379, and C1b_ AY239363) and exhibited genetic variability at mitochondrial NAD5.</p> <p>Conclusion</p> <p>This is one of the first studies to examine genetic diversity in corals and their endosymbiotic dinoflagellates sampled at the limits of the depth and light gradients for hermatypic corals. The results reveal that these corals associate with generalist endosymbiont types commonly found in shallow water corals and implies that the composition of the <it>Symbiodinium </it>community (based on ITS2) alone is not responsible for the dominance and broad depth distribution of <it>Leptoseris </it>spp. The level of genetic diversity detected in the coral NAD5 suggests that there is undescribed taxonomic diversity in the genus <it>Leptoseris </it>from Hawaii.</p

Efectos de la sustitución parcial de maíz por harina integral de mandioca sobre variables productivas de cerdos en crecimiento

La importancia de utilizar mandioca en la dieta del cerdo radica en su alto contenido de carbohidratos, siendo una excelente fuente de energía metabolizable. Esta energía es usualmente aportada por el maíz y constituye alrededor del 60 al 80% de una ración. No obstante, existen forrajes regionales potencialmente capaces de reemplazar a los tradicionalmente usados en la alimentación porcina, cuya eficiencia debe ser previamente evaluada. El trabajo tuvo la finalidad de valorar el efecto de dietas a base de mandioca sobre las variables productivas de cerdos en crecimiento, reemplazando el maíz por distintos niveles de sustitución con raíz de mandioca. Se utilizaron cuatro cerdos machos enteros, con pesos promedios de 40,4 ± 0,5 kg, alojados en corrales individuales de 2 m2 , durante 7 días de adaptación a las dietas y 14 de mediciones. Los diferentes niveles de sustitución de maíz fueron: 0, 20, 40 y 60% de raíz de mandioca para las dietas 1, 2, 3 y 4 respectivamente, todas isoenergéticas e isoproteicas. Las variables bajo estudio recibieron análisis descriptivo y su respuesta se estimó por ANOVA con un diseño en cuadrado latino y un alfa de 5%. No se registraron diferencias significativas entre las cuatro dietas para las variables productivas evaluadas. La dieta 2 fue la que generó mayor ganancia total y ganancia diaria de peso (12±1,63 kg y 1,08±0,13 kg.día–1), así como el más alto consumo diario de alimento (2,82±0,32 kg.MS.día–1). Este cerdo requirió 2,64±0,38 kg de alimento por kg de peso vivo ganado. La menor ganancia de peso se registró en el cerdo alimentado con la dieta 3 (10,75±1,26 kg), reflejada en una ganancia diaria de 0,97±0,11 kg.día–1. Se concluye que bajo las presentes condiciones de trabajo, el buen desempeño productivo del grupo experimental permite avalar la factibilidad del reemplazo parcial del maíz por harina de raíz de mandioca, en las raciones para cerdos en crecimiento.

Inorganic carbon concentrating mechanisms in free-living and symbiotic dinoflagellates and chromerids

Photosynthetic dinoflagellates are ecologically and biogeochemically important in marine and freshwater environments. However, surprisingly little is known of how this group acquires inorganic carbon or how these diverse processes evolved. Consequently, how CO2 availability ultimately influences the success of dinoflagellates over space and time remains poorly resolved compared to other microalgal groups. Here we review the evidence. Photosynthetic core dinoflagellates have a Form II RuBisCO (replaced by Form IB or Form ID in derived dinoflagellates). The in vitro kinetics of the Form II RuBisCO from dinoflagellates are largely unknown, but dinoflagellates with Form II (and other) RuBisCOs have inorganic carbon concentrating mechanisms (CCMs), as indicated by in vivo internal inorganic C accumulation and affinity for external inorganic C. However, the location of the membrane(s) at which the essential active transport component(s) of the CCM occur(s) is (are) unresolved; isolation and characterization of functionally competent chloroplasts would help in this respect. Endosymbiotic Symbiodiniaceae (in Foraminifera, Acantharia, Radiolaria, Ciliata, Porifera, Acoela, Cnidaria, and Mollusca) obtain inorganic C by transport from seawater through host tissue. In corals this transport apparently provides an inorganic C concentration around the photobiont that obviates the need for photobiont CCM. This is not the case for tridacnid bivalves, medusae, or, possibly, Foraminifera. Overcoming these long-standing knowledge gaps relies on technical advances (e.g., the in vitro kinetics of Form II RuBisCO) that can functionally track the fate of inorganic C forms