Modeling Mayfly Nymph Length Distribution and Population Dynamics Across a Gradient of Stream Temperatures and Stream Types

We analyze a process-based temperature model for the length distribution and population over time of mayfly nymphs. Model parameters are estimated using a Markov Chain Monte Carlo parameter estimation method utilizing length distribution data at five different stream sites. Two different models (a standard exponential model and a modified Weibull model) of mayfly mortality are evaluated, where in both cases mayfly length growth is a function of stream temperature. Based on model-data comparisons to the modeled length distribution and the Bayesian Information Criterion, we found that approaches that length distribution data can reliably estimate 2–3 model parameters. Future model development could include additional factors include such as upstream environmental factors, abiotic conditions, inter- specific competition, predation, or stream salinity. Outputs of this model could be applied to predict mayfly emergence across a geographic domain or to forecast mayfly population responses to climate change

BIOSAFETY. Safeguarding gene drive experiments in the laboratory.

Multiple stringent confinement strategies should be used whenever possibleThis is the author accepted manuscript. The final version is available from AAAS via http://dx.doi.org/10.1126/science.aac793

Activating PIK3CD mutations impair human cytotoxic lymphocyte differentiation and function and EBV immunity

Background Germline gain-of function (GOF) mutations in PIK3CD, encoding the catalytic p110δ subunit of phosphoinositide 3-kinase (PI3K), result in hyperactivation of the PI3K–AKT–mechanistic target of rapamycin pathway and underlie a novel inborn error of immunity. Affected subjects exhibit perturbed humoral and cellular immunity, manifesting as recurrent infections, autoimmunity, hepatosplenomegaly, uncontrolled EBV and/or cytomegalovirus infection, and increased incidence of B-cell lymphoproliferation, lymphoma, or both. Mechanisms underlying disease pathogenesis remain unknown. Objective Understanding the cellular and molecular mechanisms underpinning inefficient surveillance of EBV-infected B cells is required to understand disease in patients with PIK3CD GOF mutations, identify key molecules required for cell-mediated immunity against EBV, and develop immunotherapeutic interventions for the treatment of this and other EBV-opathies. Methods We studied the consequences of PIK3CD GOF mutations on the generation, differentiation, and function of CD8+ T cells and natural killer (NK) cells, which are implicated in host defense against infection with herpesviruses, including EBV. Results PIK3CD GOF total and EBV-specific CD8+ T cells were skewed toward an effector phenotype, with exaggerated expression of markers associated with premature immunosenescence/exhaustion and increased susceptibility to reactivation-induced cell death. These findings were recapitulated in a novel mouse model of PI3K GOF mutations. NK cells in patients with PIK3CD GOF mutations also exhibited perturbed expression of differentiation-associated molecules. Both CD8+ T and NK cells had reduced capacity to kill EBV-infected B cells. PIK3CD GOF B cells had increased expression of CD48, programmed death ligand 1/2, and CD70. Conclusions PIK3CD GOF mutations aberrantly induce exhaustion, senescence, or both and impair cytotoxicity of CD8+ T and NK cells. These defects might contribute to clinical features of affected subjects, such as impaired immunity to herpesviruses and tumor surveillance

A Mighty Small Heart: The Cardiac Proteome of Adult Drosophila melanogaster

Drosophila melanogaster is emerging as a powerful model system for the study of cardiac disease. Establishing peptide and protein maps of the Drosophila heart is central to implementation of protein network studies that will allow us to assess the hallmarks of Drosophila heart pathogenesis and gauge the degree of conservation with human disease mechanisms on a systems level. Using a gel-LC-MS/MS approach, we identified 1228 protein clusters from 145 dissected adult fly hearts. Contractile, cytostructural and mitochondrial proteins were most abundant consistent with electron micrographs of the Drosophila cardiac tube. Functional/Ontological enrichment analysis further showed that proteins involved in glycolysis, Ca2+-binding, redox, and G-protein signaling, among other processes, are also over-represented. Comparison with a mouse heart proteome revealed conservation at the level of molecular function, biological processes and cellular components. The subsisting peptidome encompassed 5169 distinct heart-associated peptides, of which 1293 (25%) had not been identified in a recent Drosophila peptide compendium. PeptideClassifier analysis was further used to map peptides to specific gene-models. 1872 peptides provide valuable information about protein isoform groups whereas a further 3112 uniquely identify specific protein isoforms and may be used as a heart-associated peptide resource for quantitative proteomic approaches based on multiple-reaction monitoring. In summary, identification of excitation-contraction protein landmarks, orthologues of proteins associated with cardiovascular defects, and conservation of protein ontologies, provides testimony to the heart-like character of the Drosophila cardiac tube and to the utility of proteomics as a complement to the power of genetics in this growing model of human heart disease

Using artificial tracers to observe timing of runoff from different landscape units in a small headwater catchment

Four artificial tracers were applied to a small headwater catchment in south western British Columbia to study runoff generated from topographically distinct landscape units. The seven hectare catchment is located in the University of British Columbia Malcolm Knapp Research Forest at low elevation (190-280 masl). A weir, multiple tipping bucket rain gauges and several piezometers were used to collect hydrological data. Three separate landscape units were identified based on topography, soil properties and proximity to the stream. The units included an area of shallow slope and deep soil, a riparian area along the intermittent stream channel and an area of very shallow soil with bedrock outcrops on a steep slope. Tracers used included rhodamine-WT, uranine, sodium chloride and potassium bromide. A suite of ion selective and fluorometric probes were used along with automated water sampling to monitor tracer breakthrough. The collected samples were analysed in the lab to validate the field measurements. Tracers were dissolved in solution and applied aerially with a backpack sprayer at the onset of forecasted precipitation events to facilitate rapid infiltration into the soil. The first application took place January 4th, 2006. Measurements were then taken continuously until March 20th, 2006, when a second round of tracers was applied to the landscape units. During the first measurement period, 532 mm of precipitation fell below the forest canopy over 75 days. During the second 78 day measurement period, 290 mm of rain fell. It was found that the overall wetness of the catchment affected travel times significantly. Large storms during the first, significantly wetter, application period exhibited similar lag times from peak event discharge to tracer arrival between the different landscape units. During small precipitation events and under dryer conditions, travel times were greatest in the area of shallow slope and deep soils. These lag times are indicative of longer pathways and perhaps the non-initiation of preferential flow below certain thresholds. In general, it was concluded that delineating catchments into groups of similar landscape units based on physical characteristics may be a promising new approach to explaining catchment runoff response.Arts, Faculty ofGeography, Department ofGraduat

Multilayer busbars for medium voltage ANPC converter dedicated to battery energy storage systems

International audienceThe increase of energy storage system power leads to open a technological pass which is to increase thevoltage level of battery racks. Available 3.3 kV Silicon Carbide (SiC) semi-conductors implemented inan ANPC topology allows tuning a 3.6 kV DC bus.Thus, researches are shifting to medium voltagesystems in which battery racks are connected in series with a middle point grounded. SiC modulesimplementation requires low inductive busbars to achieve high efficiency when rising in switchingfrequency necessary to shrink the output filter. In this paper, a methodology for reducing the parasiticinductor of the busbars (< 20 nH) is presented

Multilayer busbars for medium voltage ANPC converter dedicated to battery energy storage systems

International audienceThe increase of energy storage system power leads to open a technological pass which is to increase thevoltage level of battery racks. Available 3.3 kV Silicon Carbide (SiC) semi-conductors implemented inan ANPC topology allows tuning a 3.6 kV DC bus.Thus, researches are shifting to medium voltagesystems in which battery racks are connected in series with a middle point grounded. SiC modulesimplementation requires low inductive busbars to achieve high efficiency when rising in switchingfrequency necessary to shrink the output filter. In this paper, a methodology for reducing the parasiticinductor of the busbars (< 20 nH) is presented

Performance evaluation of SiC MOSFETs for isolated DC/DC conversion in Medium Voltage Photovoltaic Power Plants

International audienceOver the last decade, the rating of photovoltaic power stations has increased progressively; however; they still operate at low voltage (below 1500VDC for PV string side and below 800VAC-3~ for the power injection side. Hence, new architectures with an intermediate MVDC collector are investigated. This paper introduces a new topology of isolated DC/DC converter based on 1.7-kV and 3.3-kV SiC power modules, which allows the connection of PV panels to a MVDC collector upstream from the MVAC distribution grid. As a prelude to the realization of a full-scale prototype, 1.7 kV SiC MOSFETs are characterized in hard- and soft-switching condition. Finally, a study supported by simulations pointed out that the proposed converter shows a high efficiency (> 98.5%

Performance evaluation of SiC MOSFETs for isolated DC/DC conversion in Medium Voltage Photovoltaic Power Plants

International audienceOver the last decade, the rating of photovoltaic power stations has increased progressively; however; they still operate at low voltage (below 1500VDC for PV string side and below 800VAC-3~ for the power injection side. Hence, new architectures with an intermediate MVDC collector are investigated. This paper introduces a new topology of isolated DC/DC converter based on 1.7-kV and 3.3-kV SiC power modules, which allows the connection of PV panels to a MVDC collector upstream from the MVAC distribution grid. As a prelude to the realization of a full-scale prototype, 1.7 kV SiC MOSFETs are characterized in hard- and soft-switching condition. Finally, a study supported by simulations pointed out that the proposed converter shows a high efficiency (> 98.5%