Datana drexelii (Lepidoptera: Notododontidae) occurrence and larval survival on highbush blueberry cultivars

Plant genotype influences plant suitability to herbivores; domesticated plants selected for properties such as high fruit yield may be particularly vulnerable to herbivory. Cultivated strains of highbush blueberry, Vaccinium corymbosum L. can be high-quality hosts for larvae of the gregariously-feeding notodontid Datana drexelii (Hy. Edwards). We conducted an experiment assessing D. drexelii larval survival and pupal weight when fed foliage from five blueberry cultivars: ‘Bluecrop’, ‘Bluetta’, ‘Blueray’, ‘Lateblue’, and ‘Jersey’. We complemented this experimental work with repeated bush-level surveys of a managed blueberry patch for naturally occurring D. drexelii larval clusters. Larval survival and pupal weight were significantly higher on ‘Lateblue’ foliage than from the ‘Bluecrop’, ‘Bluetta’, and ‘Jersey’ cultivars. The blueberry patch surveys found more D. drexelii larval clusters on ‘Bluehaven’, ‘Collins’, and ‘Darrow’ bushes than on the cultivars ‘Earliblue’ and ‘Jersey’. The low D. drexelii occurrence and performance on the ‘Jersey’ cultivar suggests that this variety may be appropriate for areas where this pest is common; conversely, their high occurrence on ‘Bluehaven’ ‘Collins’, and ‘Darrow’ suggests that these cultivars may be particularly vulnerable. Cultivar-level variation in herbivore vulnerability highlights how understanding plant-pest interactions can help manage agricultural species

Instability of tripositronium

The stability of tripositronium, a system consisting of three electrons and three positrons, has been investigated systematically by varying the repulsion strength between like-charged particles. The possibility of the existence of a Ps3 bound state that is stable against dissociation appears utterly unlikely based on the results of variational calculations employing all-particle explicitly correlated Gaussian basis function

Spontaneous breaking of rotational symmetry in superconductors

We show that homogeneous superconductors with broken spin/isospin symmetry lower their energy via a transition to a novel superconducting state where the Fermi-surfaces are deformed to a quasi-ellipsoidal form at zero total momentum of Cooper pairs. In this state, the gain in the condensation energy of the pairs dominates over the loss in the kinetic energy caused by the lowest order (quadrupole) deformation of Fermi-surfaces from the spherically symmetric form. There are two energy minima in general, corresponding to the deformations of the Fermi-spheres into either prolate or oblate forms. The phase transition from spherically symmetric state to the superconducting state with broken rotational symmetry is of the first order.Comment: 5 pages, including 3 figures, published versio

Exotoxin-encoding gene content in community-acquired and hospital-acquired methicillin-resistant Staphylococcus aureus

AbstractReports of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) causing hospital infections are increasing, and it is questionable whether the existing molecular definition of CA-MRSA is suitable for the characterization of all strains involved. The 821 methicillin-resistant S. aureus (MRSA) isolates recovered from patients in Health Region East, Norway during the period 1991—2006 were characterized by multilocus sequence typing (MLST), staphylococcal cassette chromosome mec (SCCmec) typing, staphylococcal protein A (spa) gene typing, and their content of exotoxin-encoding genes. Cluster analysis based on exotoxin-encoding gene content was performed to separate the MRSA isolates into valid clusters with respect to microbiological characteristics. The analysis gave a four-cluster structure, and the four toxin clusters differed in the genetic lineages they included and in the diversity of the genetic lineages. A few genetic lineages were present in several toxin clusters. These results support the theory that mobile genetic elements encoding virulence genes do not move randomly among genetic lineages, but are restricted by the clonal lineages’ genetic background. Using the molecular criteria, MLST type, SCCmec type and the presence of the lucS/F-Panton–Valentine leukocidin (PVL) gene to define a CA-MRSA isolate, it was found that the CA-MRSA isolates mainly grouped together in two toxin clusters with a low prevalence of exotoxin-encoding genes. Statistical analyses supported the conclusion that toxin clusters with CA-MRSA genetic lineages were characterized by a low prevalence of exotoxin-encoding genes, whereas toxin clusters with hospital-acquired MRSA genetic lineages were characterized by a higher prevalence of exotoxin-encoding genes

Metaxa : a software tool for automated detection and discrimination among ribosomal small subunit (12S/16S/18S) sequences of archaea, bacteria, eukaryotes, mitochondria, and chloroplasts in metagenomes and environmental sequencing datasets

Peer reviewedPostprin

Phi-values in protein folding kinetics have energetic and structural components

Phi-values are experimental measures of how the kinetics of protein folding is changed by single-site mutations. Phi-values measure energetic quantities, but are often interpreted in terms of the structures of the transition state ensemble. Here we describe a simple analytical model of the folding kinetics in terms of the formation of protein substructures. The model shows that Phi-values have both structural and energetic components. In addition, it provides a natural and general interpretation of "nonclassical" Phi-values (i.e., less than zero, or greater than one). The model reproduces the Phi-values for 20 single-residue mutations in the alpha-helix of the protein CI2, including several nonclassical Phi-values, in good agreement with experiments.Comment: 15 pages, 3 figures, 1 tabl

Two-body correlation functions in nuclear matter with npnp condensate

The density, spin and isospin correlation functions in nuclear matter with a neutron-proton ($np$) condensate are calculated to study the possible signatures of the BEC-BCS crossover in the low-density region. It is shown that the criterion of the crossover (Phys. Rev. Lett. {\bf 95}, 090402 (2005)), consisting in the change of the sign of the density correlation function at low momentum transfer, fails to describe correctly the density-driven BEC-BCS transition at finite isospin asymmetry or finite temperature. As an unambiguous signature of the BEC-BCS transition, there can be used the presence (BCS regime) or absence (BEC regime) of the singularity in the momentum distribution of the quasiparticle density of states.Comment: Prepared with RevTeX4, 5p., 4 figure

Spatially inhomogeneous condensate in asymmetric nuclear matter

We study the isospin singlet pairing in asymmetric nuclear matter with nonzero total momentum of the condensate Cooper pairs. The quasiparticle excitation spectrum is fourfold split compared to the usual BCS spectrum of the symmetric, homogeneous matter. A twofold splitting of the spectrum into separate branches is due to the finite momentum of the condensate, the isospin asymmetry, or the finite quasiparticle lifetime. The coupling of the isospin singlet and triplet paired states leads to further twofold splitting of each of these branches. We solve the gap equation numerically in the isospin singlet channel in the case where the pairing in the isospin triplet channel is neglected and find nontrivial solutions with finite total momentum of the pairs. The corresponding phase assumes a periodic spatial structure which carries a isospin density wave at constant total number of particles. The phase transition from the BCS to the inhomogeneous superconducting phase is found to be first order and occurs when the density asymmetry is increased above 0.25. The transition from the inhomogeneous superconducting to the unpaired normal state is second order. The maximal values of the critical total momentum (in units of the Fermi momentum) and the critical density asymmetry at which condensate disappears are $P_c/p_F = 0.3$ and $\alpha_c = 0.41$. The possible spatial forms of the ground state of the inhomogeneous superconducting phase are briefly discussed.Comment: 13 pages, including 3 figues, uses RevTeX; minor corrections, PRC in pres