Genetic Similarities Among Geographic Isolates of Lysiphlebus testaceipes (Hymenoptera: Aphidiidae) Differing in Cold Temperature Tolerances

Lysiphlebus testaceipes (Cresson) is a solitary endoparasitoid of aphids and is the primary parasitoid attacking cereal aphids in the Great Plains, especially Schizaphis graminum (Rondani). In a previous study, it was found that a Lincoln, NE, isolate of L. testaceipes had a much higher survivorship at cold temperatures than isolates from Stillwater, OK, and Corpus Christi, TX. This suggested that the Nebraska isolate was locally adapted to the northern environment and perhaps genetically divergent from southern populations. We tested for genetic differentiation of the above isolates by sequencing portions of the COI and 16S mtDNA genes. We also examined a Florida isolate reared from Toxoptera citricida (Kirkaldy) and L. fabarum Marshall as an outgroup. The Great Plains isolates (Nebraska, Oklahoma, and Texas) were homogeneous with 0% and 0Ð0.2% sequence divergence in the COI and 16S gene fragments, respectively. The Florida isolate differed from the Great Plains isolates in nucleotide sequence by 1.4% (COI) and 0.5Ð0.7% (16S). Phylogenetic analysis placed the Florida isolate of L. testaceipes basal to the Great Plains isolates with L. fabarum, suggesting a possible species complex within L. testaceipes

Incorporating Chiral Symmetry in Extrapolations of Octet Baryon Magnetic Moments

We explore methods of extrapolating lattice calculations of hadronic observables to the physical regime, while respecting the constraints of chiral symmetry and heavy quark effective theory. In particular, we extrapolate lattice results for magnetic moments of the spin-1/2 baryon octet to the physical pion mass and compare with experimental measurements. The success previously reported for extrapolations of the nucleon magnetic moments carries over to the Sigma baryons. A study of the residual discrepancies in the Xi baryon moments suggests that it is important to have new simulation data with a more realistic strange quark mass.Comment: 9 pages, 4 figure

Chiral Behaviour of the Rho Meson in Lattice QCD

In order to guide the extrapolation of the mass of the rho meson calculated in lattice QCD with dynamical fermions, we study the contributions to its self-energy which vary most rapidly as the quark mass approaches zero; from the processes $\rho \to \omega \pi$ and $\rho \to \pi \pi$. It turns out that in analysing the most recent data from CP-PACS it is crucial to estimate the self-energy from $\rho \to \pi \pi$ using the same grid of discrete momenta as included implicitly in the lattice simulation. The correction associated with the continuum, infinite volume limit can then be found by calculating the corresponding integrals exactly. Our error analysis suggests that a factor of 10 improvement in statistics at the lowest quark mass for which data currently exists would allow one to determine the physical rho mass to within 5%. Finally, our analysis throws new light on a long-standing problem with the J-parameter.Comment: 13 pages, 7 figures. Full analytic forms of the self-energies are included and a correction in the omega-pi self-energ

Mechanotransduktion in Osteoblasten

Niertransplantatie is de beste behandeling voor nierfalen, maar sommige patiënten doen het beter dan anderen. Als we wisten waarom, zouden we misschien kunnen helpen als het minder goed gaat. Twee studies keken naar de invloed van individuele kenmerken op de patiëntenbeoordeling van gezondheid en welzijn. Eén omvatte patiënten tot 15 jaar na niertransplantatie, de ander volgde patiënten van vóór tot een jaar na transplantatie. Vele jaren met een getransplanteerde nier gaan samen met meer bijkomende aandoeningen en meer symptomen vanwege nierziekte en medicatie.Desalniettemin beoordeelden patiënten hun gezondheid even hoog dan kort na transplantatie. In sommige gevallen rapporteerden patiënten echter een verslechtering van hun gezondheid na transplantatie. Hoewel het niet mogelijk bleek deze verslechtering vooraf te voorspellen, waren deze patiënten vaak vrouwen met meer bijkomende aandoeningen en complicaties. Alhoewel de kwaliteit van leven na transplantatie vaak lager was dan patiënten hadden verwacht, waren daaruit voortvloeiende psychische klachten slechts van korte duur. Een slechte gezondheid leidde echter tot meer psychische klachten, omdat het de beoordeling van de gezondheid alsmede gevoelens van controle, optimisme en zelfrespect verlaagde. Omgekeerd resulteerden verhoogde gevoelens van controle en minder obstructie van belangrijke doelen na transplantatie in minder psychische klachten. Regelmatige controles van de patiëntenbeoordeling van gezondheid en welzijn zouden degenen kunnen identificeren die het minder goed doen. Daarna kan een beter beheer van symptomen en bijkomende aandoeningen, evenals interventies ter verbetering van het gevoel van controle, zelfrespect en het vermogen om met geblokkeerde doelen om te gaan, de gezondheidsbeoodeling en het welzijn van patiënten helpen verbeteren.Kidney transplantation is the best treatment for kidney failure, but some patients fare better than others. If we knew why, we might be able to help those who fare less well. Two studies were conducted to investigate the influence of individual characteristics on patient ratings of health and well-being. One included patients up to 15 years after kidney transplantation, the other followed patients from before to one year after transplantation. Patients who lived with a transplanted kidney for many years had more additional conditions and more symptoms because of their kidney disease and medication. Nevertheless, they rated their health equally high than those who lived shorter periods with a transplanted kidney. In some cases, however, patients reported a deterioration of their health after transplantation. While it was not possible to predict this deterioration beforehand, these patients were often women with more additional conditions and complications. Although quality of life after transplantation was often lower than patients had expected, any resulting distress was short-lived. Poor health, however, led to higher distress, because it lowered health ratings and feelings of control, optimism, and self-esteem. Conversely, increased feelings of control and less obstruction of important goals after transplantation resulted in less distress. Regular checks of patients’ health ratings and well-being could identify those who fare less well. Thereafter, enhanced management of symptoms and additional conditions, as well as interventions to improve feelings of control, self-esteem, and the ability to cope with obstructed goals might help to boost patients’ health ratings and well-being

The brainstem reticular formation is a small-world, not scale-free, network

Recently, it has been demonstrated that several complex systems may have simple graph-theoretic characterizations as so-called ‘small-world’ and ‘scale-free’ networks. These networks have also been applied to the gross neural connectivity between primate cortical areas and the nervous system of Caenorhabditis elegans. Here, we extend this work to a specific neural circuit of the vertebrate brain—the medial reticular formation (RF) of the brainstem—and, in doing so, we have made three key contributions. First, this work constitutes the first model (and quantitative review) of this important brain structure for over three decades. Second, we have developed the first graph-theoretic analysis of vertebrate brain connectivity at the neural network level. Third, we propose simple metrics to quantitatively assess the extent to which the networks studied are small-world or scale-free. We conclude that the medial RF is configured to create small-world (implying coherent rapid-processing capabilities), but not scale-free, type networks under assumptions which are amenable to quantitative measurement

Chiral Analysis of Quenched Baryon Masses

We extend to quenched QCD an earlier investigation of the chiral structure of the masses of the nucleon and the delta in lattice simulations of full QCD. Even after including the meson-loop self-energies which give rise to the leading and next-to-leading non-analytic behaviour (and hence the most rapid variation in the region of light quark mass), we find surprisingly little curvature in the quenched case. Replacing these meson-loop self-energies by the corresponding terms in full QCD yields a remarkable level of agreement with the results of the full QCD simulations. This comparison leads to a very good understanding of the origins of the mass splitting between these baryons.Comment: 23 pages, 6 figure

Chiral Extrapolation of Lattice Data for Heavy Baryons

The masses of heavy baryons containing a b quark have been calculated numerically in lattice QCD with pion masses which are much larger than its physical value. In the present work we extrapolate these lattice data to the physical mass of the pion by applying the effective chiral Lagrangian for heavy baryons, which is invariant under chiral symmetry when the light quark masses go to zero and heavy quark symmetry when the heavy quark masses go to infinity. A phenomenological functional form with three parameters, which has the correct behavior in the chiral limit and appropriate behavior when the pion mass is large, is proposed to extrapolate the lattice data. It is found that the extrapolation deviates noticably from the naive linear extrapolation when the pion mass is smaller than about 500MeV. The mass differences between Sigma_b and Sigma_b^* and between Sigma_b^{(*)} and Lambda_b are also presented. Uncertainties arising from both lattice data and our model parameters are discussed in detail. We also give a comparision of the results in our model with those obtained in the naive linear extrapolations.Comment: 29 pages, 9 figure

Chiral extrapolation of lattice data for B-meson decay constant

The B-meson decay constant fB has been calculated from unquenched lattice QCD in the unphysical region. For extrapolating the lattice data to the physical region, we propose a phenomenological functional form based on the effective chiral perturbation theory for heavy mesons, which respects both the heavy quark symmetry and the chiral symmetry, and the non-relativistic constituent quark model which is valid at large pion masses. The inclusion of pion loop corrections leads to nonanalytic contributions to fB when the pion mass is small. The finite-range regularization technique is employed for the resummation of higher order terms of the chiral expansion. We also take into account the finite volume effects in lattice simulations. The dependence on the parameters and other uncertainties in our model are discussed.Comment: 11 pages, 3 Postscript figures, accepted for publication in EPJ