Optimal Detection Strategies for an Established Invasive Forest Pest

When it comes to invasive species management, economists have focused on the trade-off between prevention of potential invasions and management of established populations. The intermediate step-detection of established populations on the landscape so that management can commence-has only recently received attention in the economics literature. A recent paper (Mehta et al., 2007) explores how biological and economic parameters affect optimal detection spending, recognizing that greater expenditures on detection can lead to smaller and more manageable population sizes upon detection because populations are discovered early. We build upon this framework by considering the optimal spatial allocation of detection effort when it is impossible to stop the advance of the main front of an invasive species, yet it is beneficial to detect and control sub-populations of the species that erupt ahead of the front. Our approach recognizes that the duration of management of sub-populations is constrained by the amount of time remaining before the main front arrives. Locations close to the front have less time remaining than locations that are more distant. These differences imply different levels of potential benefit from early detection; in particular, shorter management horizons translate into lower benefits from intervention. The optimal intensity of detection effort varies over space along with this variation in the benefits from management.Resource /Energy Economics and Policy,

Search for Hidden photons with Sumico

We searched for solar hidden photons in the visible photon energy range using a hidden photon detector add-on attached to Sumico. It consists of a parabolic mirror of dia. 0.5m and f=1m installed in a vacuum chamber, and a low noise photomultiplier tube at the focal point. No evidence for the existence of hidden photons was found in the latest measurement giving a new limit on the photon-hidden photon mixing parameter in the hidden photon mass range 0.001-1eV.Comment: 6 pages. Contributed to the 9th Patras Workshop on Axions, WIMPs and WISPs, Mainz, June 24-28, 201

Strong valence fluctuation in the quantum critical heavy fermion superconductor beta-YbAlB4: A hard x-ray photoemission study

Electronic structures of the quantum critical superconductor beta-YbAlB4 and its polymorph alpha-YbAlB4 are investigated by using bulk-sensitive hard x-ray photoemission spectroscopy. From the Yb 3d core level spectra, the values of the Yb valence are estimated to be ~2.73 and ~2.75 for alpha- and beta-YbAlB4, respectively, thus providing clear evidence for valence fluctuations. The valence band spectra of these compounds also show Yb2+ peaks at the Fermi level. These observations establish an unambiguous case of a strong mixed valence at quantum criticality for the first time among heavy fermion systems, calling for a novel scheme for a quantum critical model beyond the conventional Doniach picture in beta-YbAlB4.Comment: 4 pages, 3 figures, revised version accepted for publication in PR

Evolution of DNA Double-Strand Break Repair by Gene Conversion: Coevolution Between a Phage and Restriction-Modification System

The necessity to repair genome damage has been considered to be an immediate factor responsible for the origin of sex. Indeed, attack by a cellular restriction enzyme of invading DNA from several bacteriophages initiates recombinational repair by gene conversion if there is homologous DNA. In the present work, we modeled the interaction between a bacteriophage and a bacterium carrying a restriction enzyme as antagonistic coevolution. We assume a locus on the bacteriophage genome has either a restriction-sensitive or a -resistant allele, and another locus determines whether it is recombination/repair-proficient or -defective. A restriction break can be repaired by a co-infecting phage genome if one of them is recombination/repair-proficient. We define the fitness of phage (resistant/sensitive and repair-positive/-negative) genotypes and bacterial (restriction-positive/-negative) genotypes by assuming random encounter of the genotypes, with a given probabilities of single and double infections, and the costs of resistance, repair and restriction. Our results show the evolution of the repair allele depends on b1 / b0 , the ratio of the burst size b1 under damage to host cell physiology induced by an unrepaired double-strand break to the default burst size b0 . It was not until this effect was taken into account that the evolutionary advantage of DNA repair became apparent

Monoaminergic modulation of photoreception in ascidian:evidence for a proto-hypothalamo-retinal territory

Background : The retina of craniates/vertebrates has been proposed to derive from a photoreceptor prosencephalic territory in ancestral chordates, but the evolutionary origin of the different cell types making the retina is disputed. Except for photoreceptors, the existence of homologs of retinal cells remains uncertain outside vertebrates. Methods : The expression of genes expressed in the sensory vesicle of the ascidian Ciona intestinalis including those encoding components of the monoaminergic neurotransmission systems, was analyzed by in situ hybridization or in vivo transfection of the corresponding regulatory elements driving fluorescent reporters. Modulation of photic responses by monoamines was studied by electrophysiology combined with pharmacological treatments. Results : We show that many molecular characteristics of dopamine-synthesizing cells located in the vicinity of photoreceptors in the sensory vesicle of the ascidian Ciona intestinalis are similar to those of amacrine dopamine cells of the vertebrate retina. The ascidian dopamine cells share with vertebrate amacrine cells the expression of the key-transcription factor Ptf1a, as well as that of dopamine-synthesizing enzymes. Surprisingly, the ascidian dopamine cells accumulate serotonin via a functional serotonin transporter, as some amacrine cells also do. Moreover, dopamine cells located in the vicinity of the photoreceptors modulate the light-off induced swimming behavior of ascidian larvae by acting on alpha2-like receptors, instead of dopamine receptors, supporting a role in the modulation of the photic response. These cells are located in a territory of the ascidian sensory vesicle expressing genes found both in the retina and the hypothalamus of vertebrates (six3/6, Rx, meis, pax6, visual cycle proteins). Conclusion : We propose that the dopamine cells of the ascidian larva derive from an ancestral multifunctional cell population located in the periventricular, photoreceptive field of the anterior neural tube of chordates, which also gives rise to both anterior hypothalamus and the retina in craniates/vertebrates. It also shows that the existence of multiple cell types associated with photic responses predates the formation of the vertebrate retina

Triply coupled analysis method for thin flexible piezoelectric bimorph in fluid

Piezoelectric–structure–fluidinteractionisacomplexmultiphysicscoupledphenomena appears wherein piezoelectric devices are in contact or surrounded by the fluid media. The piezoelectric energy harvesting using ocean waves, wind flow, and mechanical vibrations are some of the popular energy savaging methods wherein thin piezoelectric bimorphs surrounded by the fluid is used for power harvesting. With recent advances on micro air vehicles actuated by piezoelectric bimorph actuators in the fluid (surrounding media) as attracted the of piezoelectric–structure–fluid interaction. Generally, in these applications, the piezoelectric bimorph is thin, flexible, and surrounded by the fluid. The large deformation of the thin flexible piezoelectric bimorph causes strong interaction with the electric field (piezoelectric effect) and the surrounding fluid, and inversely, these two fields significantly affect the structure. The piezoelectric field–structure–fluid interaction analysis is very significant. In this work, we propose a hierarchal decomposition method to solve piezoelectric–structure–fluid interaction of a piezoelectric bimorph in the fluid. The proposed method is applied to a flexible restrictor flap in converging channel, where the rubber flap is replaced by the piezoelectric bimorphs made of PVDF or PZT–5H. The resonance frequency of the piezoelectric bimorph in the fluid agrees well with the theoretical and numerical pure FSI cases. These results show a good agreement with the previous studies

Coupled solid piezoelectric and shell inversepiezoelectric analysis using partitioned method for thin piezoelectric bimorph with metal layers

In this study, the coupled solid piezoelectric and shell inverse-piezoelectric analysis method for a thin piezoelectric bimorph with metal layers is proposed. The piezoelectric bimorph is usually thin and includes the metal layers such as the electrode and the shim plate. In the proposed method, the solid and shell elements are used for the piezoelectric and inverse-piezoelectric analyses, respectively, since the solid elements can describe the various types of the distributions of the electric potential along the thickness, and the shell elements are suitable for analyzing the thin structure. The block Gauss-Seidel method is used to couple the solid piezoelectric and shell inverse-piezoelectric analyses. In the iterative passing of the solution variables, the transformation method is used between the solid and shell elements. The rules of mixture for the bending rigidity and the mass are used for modeling the single shell structure in the inverse-piezoelectric analysis. A pseudo-piezoelectric modeling for the conductor is proposed to consider the metal layers in the piezoelectric analysis. This modeling allows us to reuse existing programs of the piezoelectric analysis without any modification

Determination of the local structure of Sr2−x_{2-x}Mx_xIrO4_4 (M = K, La) as a function of doping and temperature

The local structure of correlated spin-orbit insulator Sr$_{2-x}$M$_x$IrO$_4$ (M = K, La) has been investigated by Ir L$_3$-edge extended x-ray absorption fine structure measurements. The measurements were performed as a function of temperature for different dopings induced by substitution of Sr with La or K. It is found that Ir-O bonds have strong covalency and they hardly show any change across the N\'eel temperature. In the studied doping range, neither Ir-O bonds nor their dynamics, measured by their mean square relative displacements, show any appreciable change upon carrier doping, indicating possibility of a nanoscale phase separation in the doped system. On the other hand, there is a large increase of the static disorder in Ir-Sr correlation, larger for K doping than La doping. Similarities and differences with respect to the local lattice displacements in cuprates are briefly discussed.Comment: Main text: 6 pages, 4 figures, Supplemental information: 2 pages, 2 figure

Hiding solutions in random satisfiability problems: A statistical mechanics approach

A major problem in evaluating stochastic local search algorithms for NP-complete problems is the need for a systematic generation of hard test instances having previously known properties of the optimal solutions. On the basis of statistical mechanics results, we propose random generators of hard and satisfiable instances for the 3-satisfiability problem (3SAT). The design of the hardest problem instances is based on the existence of a first order ferromagnetic phase transition and the glassy nature of excited states. The analytical predictions are corroborated by numerical results obtained from complete as well as stochastic local algorithms.Comment: 5 pages, 4 figures, revised version to app. in PR