A synergistic mixture of diatomaceous earth and deltamethrin to control stored grain insects

In order to mitigate the negative effect of diatomaceous earth (DE) on bulk density and grain flowability, DE was mixed with other insecticides. This paper investigates the efficacy of a mixture of DE and deltamethrin against Sitophilus zeamais, the maize weevil, Rhyzopertha dominica, the lesser grain borer, and Tribolium castaneum, the red flour beetle. Five mixtures of DE and deltamethrin were prepared in the laboratory containing the same quantity of DE and different concentrations of the active ingredient of deltamethrin. The ratio of DE and deltamethrin in formulations were: DE 1 part: deltamethrin 0.00025, 0.00050, 0.00075, 0.0010 and 0.00125 parts. Co-toxicity and Co-efficient values higher than 100 (S. zeamais 170–386, R. dominica 188–601, and T. castaneum 157–285) indicated synergism between DE and deltamethrin.Keywords: Diatomaceous earth, Deltamethrin, Ready to use mixture, Co-toxicity, Co-efficient, Synergism, Grain insect pest

Tunable linear and quadratic optomechanical coupling for a tilted membrane within an optical cavity: theory and experiment

We present an experimental study of an optomechanical system formed by a vibrating thin semi-transparent membrane within a high-finesse optical cavity. We show that the coupling between the optical cavity modes and the vibrational modes of the membrane can be tuned by varying the membrane position and orientation. In particular we demonstrate a large quadratic dispersive optomechanical coupling in correspondence with avoided crossings between optical cavity modes weakly coupled by scattering at the membrane surface. The experimental results are well explained by a first order perturbation treatment of the cavity eigenmodes.Comment: 10 pages, 6 figure

Time-Resolved Studies of Stick-Slip Friction in Sheared Granular Layers

Sensitive and fast force measurements are performed on sheared granular layers undergoing stick-slip motion, along with simultaneous imaging. A full study has been done for spherical particles with a +-20% size distribution. Stick-slip motion due to repetitive fluidization of the layer occurs for low driving velocities. Between major slip events, slight creep occurs that is variable from one event to the next. The effects of changing the stiffness k and velocity V of the driving system are studied in detail. The stick-slip motion is almost periodic for spherical particles over a wide range of parameters, but becomes irregular when k is large and V is relatively small. At larger V, the motion becomes smoother and is affected by the inertia of the upper plate bounding the layer. Measurements of the period T and amplitude A of the relative motion are presented as a function of V. At a critical value Vc, a transition to continuous sliding motion occurs that is discontinuous for k not too large. The time dependence of the instantaneous velocity of the upper plate and the frictional force produced by the granular layer are determined within individual slipping events. The force is a multi-valued function of the instantaneous velocity, with pronounced hysteresis and a sudden drop prior to resticking. Measurements of vertical displacement reveal a small dilation of the material (about one tenth of the mean particle size in a layer 20 particles deep) associated with each slip event. Finally, optical imaging reveals that localized microscopic rearrangements precede (and follow) each slip event. The behavior of smooth particles is contrasted with that of rough particles.Comment: 20, pages, 17 figures, to appear in Phys. Rev.

The Generalized Star Product and the Factorization of Scattering Matrices on Graphs

In this article we continue our analysis of Schr\"odinger operators on arbitrary graphs given as certain Laplace operators. In the present paper we give the proof of the composition rule for the scattering matrices. This composition rule gives the scattering matrix of a graph as a generalized star product of the scattering matrices corresponding to its subgraphs. We perform a detailed analysis of the generalized star product for arbitrary unitary matrices. The relation to the theory of transfer matrices is also discussed

Surface Roughness and Effective Stick-Slip Motion

The effect of random surface roughness on hydrodynamics of viscous incompressible liquid is discussed. Roughness-driven contributions to hydrodynamic flows, energy dissipation, and friction force are calculated in a wide range of parameters. When the hydrodynamic decay length (the viscous wave penetration depth) is larger than the size of random surface inhomogeneities, it is possible to replace a random rough surface by effective stick-slip boundary conditions on a flat surface with two constants: the stick-slip length and the renormalization of viscosity near the boundary. The stick-slip length and the renormalization coefficient are expressed explicitly via the correlation function of random surface inhomogeneities. The effective stick-slip length is always negative signifying the effective slow-down of the hydrodynamic flows by the rough surface (stick rather than slip motion). A simple hydrodynamic model is presented as an illustration of these general hydrodynamic results. The effective boundary parameters are analyzed numerically for Gaussian, power-law and exponentially decaying correlators with various indices. The maximum on the frequency dependence of the dissipation allows one to extract the correlation radius (characteristic size) of the surface inhomogeneities directly from, for example, experiments with torsional quartz oscillators.Comment: RevTeX4, 14 pages, 3 figure

Dynamic response of HTS composite tapes to pulsed currents

Dynamic voltage-current characteristics of an HTS Ag/BiSCCO composite tape are studied both experimentally and theoretically. The tape is subjected by pulsed currents with different shapes and magnitude and voltage traces are measured using the four-point method with different location of potential taps on the sample surface. Clockwise and anticlockwise hysteresis loops are obtained for the same sample depending on location of the potential taps. The dynamic characteristics deviate substantially from the DC characteristic, especially in the range of low voltages where a criterion for the critical current value is usually chosen (1-10 mkV/cm). The critical current determined from dynamic characteristics and its change with the pulse magnitude depend on location of the potential taps and on the curve branch chosen for the critical current determination (ascending or descending). The theoretical analysis is based on a model of the magnetic flux diffusion into a composite tape for a superconductor described by the flux creep characteristic. Numerical simulation based on this model gives the results in good agreement with the experimental ones and explains the observed peculiarities of the dynamic characteristics of HTS composite tapes. The difference between the magnetic diffusion into a tape and a slab is discussed.Comment: 18 pages, 13 figure

Importing genetically altered animals : ensuring quality

The reproducibility of research using laboratory animals requires reliable management of their quality, in particular of their genetics, health and environment, all of which contribute to their phenotypes. The point at which these biological materials are transferred between researchers is particularly sensitive, as it may result in a loss of integrity of the animals and/or their documentation. Here, we describe the various aspects of laboratory animal quality that should be confirmed when sharing rodent research models. We also discuss how repositories of biological materials support the scientific community to ensure the continuity of the quality of laboratory animals. Both the concept of quality and the role of repositories themselves extend to all exchanges of biological materials and all networks that support the sharing of these reagents.Peer reviewe

Inhibition of cathepsin B by caspase-3 inhibitors blocks programmed cell death in <i>Arabidopsis</i>

Programmed cell death (PCD) is used by plants for development and survival to biotic and abiotic stresses. The role of caspases in PCD is well established in animal cells. Over the past 15 years, the importance of caspase-3-like enzymatic activity for plant PCD completion has been widely documented despite the absence of caspase orthologues. In particular, caspase-3 inhibitors blocked nearly all plant PCD tested. Here, we affinity-purified a plant caspase-3-like activity using a biotin-labelled caspase-3 inhibitor and identified Arabidopsis thaliana cathepsin B3 (AtCathB3) by liquid chromatography with tandem mass spectrometry (LC-MS/MS). Consistent with this, recombinant AtCathB3 was found to have caspase-3-like activity and to be inhibited by caspase-3 inhibitors. AtCathepsin B triple-mutant lines showed reduced caspase-3-like enzymatic activity and reduced labelling with activity-based caspase-3 probes. Importantly, AtCathepsin B triple mutants showed a strong reduction in the PCD induced by ultraviolet (UV), oxidative stress (H2O2, methyl viologen) or endoplasmic reticulum stress. Our observations contribute to explain why caspase-3 inhibitors inhibit plant PCD and provide new tools to further plant PCD research. The fact that cathepsin B does regulate PCD in both animal and plant cells suggests that this protease may be part of an ancestral PCD pathway pre-existing the plant/animal divergence that needs further characterisation

The Role of Eif6 in Skeletal Muscle Homeostasis Revealed by Endurance Training Co-expression Networks

Regular endurance training improves muscle oxidative capacity and reduces the risk of age-related disorders. Understanding the molecular networks underlying this phenomenon is crucial. Here, by exploiting the power of computational modeling, we show that endurance training induces profound changes in gene regulatory networks linking signaling and selective control of translation to energy metabolism and tissue remodeling. We discovered that knockdown of the mTOR-independent factor Eif6, which we predicted to be a key regulator of this process, affects mitochondrial respiration efficiency, ROS production, and exercise performance. Our work demonstrates the validity of a data-driven approach to understanding muscle homeostasis

The role of CO2 variability and exposure time for biological impacts of ocean acidification

Biological impacts of ocean acidification have mostly been studied using future levels of CO without consideration of natural variability or how this modulates both duration and magnitude of CO exposure. Here we combine results from laboratory studies on coral reef fish with diurnal in situ CO data from a shallow coral reef, to demonstrate how natural variability alters exposure times for marine organisms under increasingly high-CO conditions. Large in situ CO variability already results in exposure of coral reef fish to short-term CO levels higher than laboratory-derived critical CO levels (∼600 μatm). However, we suggest that the in situ exposure time is presently insufficient to induce negative effects observed in laboratory studies. Our results suggest that both exposure time and the magnitude of CO levels will be important in determining the response of organisms to future ocean acidification, where both will increase markedly with future increases in CO. Key Points Seawater CO2 variability alters in situ CO2 exposure time and magnitude Fish are presently exposed to short-term CO2 levels above critical values Acidification experiments should consider both CO2 level and exposure time