Realization of a feedback controlled flashing ratchet

A flashing ratchet transports diffusive particles using a time-dependent, asymmetric potential. Particle speed is predicted to increase when a feedback algorithm based on particle positions is used. We have experimentally realized such a feedback ratchet using an optical line trap, and observed that use of feedback increases velocity by up to an order of magnitude. We compare two different feedback algorithms for small particle numbers, and find good agreement with simulations. We also find that existing algorithms can be improved to be more tolerant to feedback delay times

The influence of depth and velocity on age‐0 Scaphirhynchus sturgeon prey consumption: Implications for aquatic habitat restoration

After the pallid sturgeon (Scaphirhynchus albus) was listed as endangered in 1990, a variety of management actions focusing on early life history needs have been implemented to aid species recovery. Given the scarcity of age‐0 pallid sturgeon, managers and scientists have relied on sympatric congeners to evaluate the effectiveness of management actions in the short term; however, increased understanding of habitat requirements for age‐0 Scaphirhynchus sturgeon is still needed to appropriately focus management efforts. Recently, a lack of food‐producing and foraging habitats were proposed as potential limiting factors for pallid sturgeon, and the purpose of this study was to evaluate the current definition of these habitats at multiple spatial scales using data from age‐0 Scaphirhynchus sturgeon (shovelnose sturgeon [Scaphirhynchus platyrhynchus] or hybrid [shovelnose sturgeon x pallid sturgeon]). Results showed the water depths and velocities that currently define age‐0 pallid sturgeon foraging habitat had little effect on age‐0 Scaphirhynchus sturgeon prey consumption. Similar results occurred when evaluating the relationship between prey consumption and food‐producing habitat present 10, 20, and 30 days before capture. Assuming that individuals captured during this study were a valid surrogate, these results suggest that increasing foraging and food‐producing habitat as defined by the current depth and velocity criteria is unlikely to result in the desired benefits of increased growth and survival of age‐0 pallid sturgeon

Effect of Protein Restriction During Mid-to Late Gestation of Beef Cows on Female Offspring Fertility, Lactation Performance and Calves Development

Cow calf operation in Argentina are managed under extensive grazing condition and the quality of forages is often poor during second half of gestation. Protein restriction in bovine gestation affects production traits in progeny. The present work investigated the effects of two levels of crude protein (CP) provided to mature dams during late gestation on subsequent heifer’s growth postweaning, reproductive performance, milk production and grand offspring evolution. At 121 d prepartum, 68 multiparous Angus cows were randomly assigned to low protein (LP, 6% CP) or high protein (HP, 12% CP) at 12 pens per treatment group. Following calving, all cow/calf pairs were housed together until weaning, then female progeny were removed and maintained on pasture as a single group. At puberty (P = 0.01) and pregnancy determination (P = 0.05) the HP heifers were heavier than LP heifers. The LM area was greater at 20 mo of age in HP compared to LP heifers (P = 0.01) and the HP heifers had greater 12th rib fat thickness at 30 and 35 mo of age (P = 0.02). Serum IGF-1 concentration was greater in HP heifers compared to LP heifers (P = 0.05). No dam nutrition effects were found on offspring age at puberty (P = 0.98), final pregnancy rate (P = 0.28) or milk yield (P = 0.76) but heifers born to LP dams had greater milk protein percentage (P = 0.04) and tended to produce increased milk fat percentage (P = 0.08) compared with HP heifers. The LP grand offspring grew faster from birth until weaning compared with HP grand offspring (P < 0.01) with reduced insulin concentrations (P = 0.03) and tended to have increased glucose concentrations than HP calves (P = 0.09). Protein supplementation during late gestation does not affect reproductive performance of the offspring heifers but did impact their BW evolution, milk quality and grand offspring performance. Implications: The use of diet with low amount of protein which the female fetus is exposed in utero can affect her subsequent development and ability to nourish subsequent generations.EEA Cuenca del SaladoFil: Lopez Valiente, Sebastian. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Cuenca del Salado; ArgentinaFil: Maresca, Sebastian. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Cuenca del Salado; ArgentinaFil: Rodriguez, Alejandro Martin. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Cuenca del Salado; ArgentinaFil: Long, Nathan M. Clemson University. Department of Animal and Veterinary Sciences; Estados UnidosFil: Quintans, Graciela I. Instituto Nacional de Investigación Agropecuaria (INIA); UruguayFil: Palladino, Rafael Alejandro. Universidad Nacional de Lomas de Zamora. Facultad de Ciencias Agrarias; ArgentinaFil: Palladino, Rafael Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Exposure to toxic fescue during late gestation on beef cows: effects on cow performance and offspring performance from birth to weaning

To examine the effects of endophyte-infected tall fescue during late gestation on maternal and offspring performance, multiparous Angus cows (n = 40) were bred via AI and allocated into grazing treatments: toxic (E+) or nontoxic (E-) endophyte tall fescue. Cows body weight (BW), body temperature, body condition score (BCS), and respiration rate were recorded and blood samples collected on 180, 210 and 240 days of gestation. Calf's BW were recorded at birth and weaning. Cow/calf pairs were managed as one group on nontoxic pasture from calving until weaning (180 days of age). Body weight decreased (P = 0.022) and body temperature increased (P < 0.0001) at day 240 in E+ compared to E-cows. BCS did not differ (P = 0.891) between treatments. Respiratory frequency increased (P = 0.003) in E+ compared to E-cows. Ergovaline concentration of urine increased (P = 0.003) at day 210 and 240 in E+ compared to E-cows. Prolactin concentrations decreased (P < 0.0001) at day 210 in E+ compared to E-cows. Birth and weaning weight decreased (P < 0.05) in calves from E+ cows compared to E-cows. Overall, grazing endophyte-infected tall fescue reduced maternal and subsequent offspring BW.EEA BalcarceFil: McCarty, Keelee. Clemson University. Department of Animal and Veterinary Sciences; Estados UnidosFil: Bence, Ángel. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Veterinarias; ArgentinaFil: Maresca, Sebastián. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Cuenca del Salado; Argentina.Fil: Lopez Valiente, Sebastián. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Cuenca del Salado; Argentina.Fil: Rodriguez, Alejandro. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Cuenca del Salado; Argentina.Fil: Cantón, Germán José. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Balcarce; ArgentinaFil: Long, Nathan M. Clemson University. Department of Animal and Veterinary Sciences; Estados Unido

Different levels of overnutrition and weight gain during pregnancy have differential effects on fetal growth and organ development

<p>Abstract</p> <p>Background</p> <p>Nearly 50% of U.S. women of child-bearing age are overweight or obese, conditions linked to offspring obesity and diabetes.</p> <p>Methods</p> <p>Utilizing the sheep, females were fed a highly palatable diet at two levels of overfeeding designed to induce different levels of maternal body weight increase and adiposity at conception, and from conception to midgestation. Fetal growth and organ development were then evaluated at midgestation in response to these two different levels of overfeeding. Ewes were fed to achieve: 1) normal weight gain (control, C), 2) overweight (125% of National Research Council [NRC] recommendations, OW125) or 3) obesity (150% of NRC recommendations, OB150) beginning 10 wks prior to breeding and through midgestation. Body fat % and insulin sensitivity were assessed at three points during the study: 1) diet initiation, 2) conception and 3) mid-gestation. Ewes were necropsied and fetuses recovered at mid-gestation (day 78).</p> <p>Results</p> <p>OB150 ewes had a higher % body fat than OW125 ewes prior to breeding (P = 0.03), but not at mid-gestation (P = 0.37). Insulin sensitivity decreased from diet initiation to mid-gestation (P = 0.04), and acute insulin response to glucose tended to be greater in OB150 ewes than C ewes (P = 0.09) and was greater than in OW125 ewes (P = 0.02). Fetal crown-rump length, thoracic and abdominal girths, and fetal perirenal fat were increased in the OW125 and OB150 versus C ewes at mid-gestation. However, only fetal heart, pancreas, and liver weights, as well as lipid content of fetal liver, were increased (P < 0.05) in OB150 ewes versus both C and OW125 ewes at midgestation.</p> <p>Conclusions</p> <p>These data demonstrate that different levels of overfeeding, resulting in differing levels of maternal weight gain and adiposity prior to and during pregnancy, lead to differential effects on fetal overgrowth and organ development.</p

Mutations in Mll2, an H3K4 methyltransferase, result in insulin resistance and impaired glucose tolerance in mice.

We employed a random mutagenesis approach to identify novel monogenic determinants of type 2 diabetes. Here we show that haplo-insufficiency of the histone methyltransferase myeloid-lineage leukemia (Mll2/Wbp7) gene causes type 2 diabetes in the mouse. We have shown that mice heterozygous for two separate mutations in the SET domain of Mll2 or heterozygous Mll2 knockout mice were hyperglycaemic, hyperinsulinaemic and developed non-alcoholic fatty liver disease. Consistent with previous Mll2 knockout studies, mice homozygous for either ENU mutation (or compound heterozygotes) died during embryonic development at 9.5-14.5 days post coitum. Heterozygous deletion of Mll2 induced in the adult mouse results in a normal phenotype suggesting that changes in chromatin methylation during development result in the adult phenotype. Mll2 has been shown to regulate a small subset of genes, a number of which Neurod1, Enpp1, Slc27a2, and Plcxd1 are downregulated in adult mutant mice. Our results demonstrate that histone H3K4 methyltransferase Mll2 is a component of the genetic regulation necessary for glucose homeostasis, resulting in a specific disease pattern linking chromatin modification with causes and progression of type 2 diabetes, providing a basis for its further understanding at the molecular level

Hysteresis and precession of a swirling jet normal to a wall

Interaction of a swirling jet with a no-slip surface has striking features of fundamental and practical interest. Different flow states and transitions among them occur at the same conditions in combustors, vortex tubes, and tornadoes. The jet axis can undergo precession and bending in combustors; this precession enhances large-scale mixing and reduces emissions of NOx. To explore the mechanisms of these phenomena, we address conically similar swirling jets normal to a wall. In addition to the Serrin model of tornadolike flows, a new model is developed where the flow is singularity free on the axis. New analytical and numerical solutions of the Navier-Stokes equations explain occurrence of multiple states and show that hysteresis is a common feature of wall-normal vortices or swirling jets no matter where sources of motion are located. Then we study the jet stability with the aid of a new approach accounting for deceleration and nonparallelism of the base flow. An appropriate transformation of variables reduces the stability problem for this strongly nonparallel flow to a set of ordinary differential equations. A particular flow whose stability is studied in detail is a half-line vortex normal to a rigid plane-a model of a tornado and of a swirling jet issuing from a nozzle in in a combustor. Helical counter-rotating disturbances appear to be first growing as Reynolds number increases. Disturbance frequency changes its sign along the neutral curve while the wave number remains positive. Short disturbance waves propagate downstream and long waves propagate upstream. This helical instability causes bending of the vortex axis and its precession-the effects observed in technological flows and in tornadoes.V. Shtern, J. M