Surprisingly Little Population Genetic Structure In A Fungus-Associated Beetle Despite Its Exploitation Of Multiple Hosts

In heterogeneous environments, landscape features directly affect the structure of genetic variation among populations by functioning as barriers to gene flow. Resource-associated population genetic structure, in which populations that use different resources (e.g., host plants) are genetically distinct, is a well-studied example of how environmental heterogeneity structures populations. However, the pattern that emerges in a given landscape should depend on its particular combination of resources. If resources constitute barriers to gene flow, population differentiation should be lowest in homogeneous landscapes, and highest where resources exist in equal proportions. In this study, we tested whether host community diversity affects population genetic structure in a beetle (Bolitotherus cornutus) that exploits three sympatric host fungi. We collected B.cornutus from plots containing the three host fungi in different proportions and quantified population genetic structure in each plot using a panel of microsatellite loci. We found no relationship between host community diversity and population differentiation in this species; however, we also found no evidence of resource-associated differentiation, suggesting that host fungi are not substantial barriers to gene flow. Moreover, we detected no genetic differentiation among B.cornutus populations separated by several kilometers, even though a previous study demonstrated moderate genetic structure on the scale of a few hundred meters. Although we found no effect of community diversity on population genetic structure in this study, the role of host communities in the structuring of genetic variation in heterogeneous landscapes should be further explored in a species that exhibits resource-associated population genetic structure

Independent uncertainty estimates for coefficient based sea surface temperature retrieval from the Along-Track Scanning Radiometer instruments

We establish a methodology for calculating uncertainties in sea surface temperature estimates from coefficient based satellite retrievals. The uncertainty estimates are derived independently of in-situ data. This enables validation of both the retrieved SSTs and their uncertainty estimate using in-situ data records. The total uncertainty budget is comprised of a number of components, arising from uncorrelated (eg. noise), locally systematic (eg. atmospheric), large scale systematic and sampling effects (for gridded products). The importance of distinguishing these components arises in propagating uncertainty across spatio-temporal scales. We apply the method to SST data retrieved from the Advanced Along Track Scanning Radiometer (AATSR) and validate the results for two different SST retrieval algorithms, both at a per pixel level and for gridded data. We find good agreement between our estimated uncertainties and validation data. This approach to calculating uncertainties in SST retrievals has a wider application to data from other instruments and retrieval of other geophysical variables

Circadian Activity of Topical 0.05% Betamethasone Dipropionate in Human Skin In Vivo

The influence of treatment duration, vehicle, and time of day of application on topical 0.05% betamethasone dipropionate uptake into human stratum corneum and the resulting skin- blanching response was investigated in human subjects. Drug uptake into stratum corneum and the resulting skin color changes measured with a chromameter demonstrate an equilibrium delay. Maximal drug uptake occurred at 2 h, whereas maximal skin color changes occurred 6h after a single application. Extent of decreased skin color was dependent on vehicle, treatment duration, and time of day of application. Time of maximal decreased skin color occurred at midnight independent of vehicle, treatment duration, or time of day of application. This time of maximal drug activity coincides with the well-known time period of lowest circulating cortisol concentrations (2000-0400 h). Application of a single 2- or 6-h dose of the 0.05% cream at 1600h produced more extensive and prolonged changes in skin color over 24h than a 0900-h application in the same subject. These data demonstrate that the extent and duration of topical corticosteroid activity in human skin is influenced by vehicle, treatment duration, and time of day of application. The prolonged changes in skin color measured with a single dose applied at 1600h suggest that a once-a-day dosing regimen in the late afternoon may be sufficient for dermatologic therapy. Elucidation of these circadian responses with topical corticosteroids may provide a rational basis for the future re-evaluation of the appropriate therapeutic regimen with this class of drugs in dermatologic medicine

Generation of angular-momentum-dominated electron beams from a photoinjector

Various projects under study require an angular-momentum-dominated electron beam generated by a photoinjector. Some of the proposals directly use the angular-momentum-dominated beams (e.g. electron cooling of heavy ions), while others require the beam to be transformed into a flat beam (e.g. possible electron injectors for light sources and linear colliders). In this paper, we report our experimental study of an angular-momentum-dominated beam produced in a photoinjector, addressing the dependencies of angular momentum on initial conditions. We also briefly discuss the removal of angular momentum. The results of the experiment, carried out at the Fermilab/NICADD Photoinjector Laboratory, are found to be in good agreement with theoretical and numerical models.Comment: 8 pages, 7 figures, submitted to Phys. Rev. ST Accel. Beam

Microclimatic interactions in agroforestry systems

The interaction of the components of an agroforestry system with elements of microclimate is presented in terms of the interception by foliage of radiant energy and of rainfall; and of the temperature, humidity and windspeed of air surrounding the foliage. Most of the measurements reported are from a trial in which pearl millet was grown at ICRISAT, Hyderabad, between hedges of Leucaena leucocephala Lam. In terms of microclimate, the main advantage of the alley system was to intercept more light throughout the year and therefore to produce more biomass. Temperatureand humidity within the alleys differed little from values in the open but windspeed was substantially less. The main disadvantage of the system in terms of pearl millet production was therefore competition below ground rather than abov

Evidence of vectorial photoelectric effect on Copper

Quantum Efficiency (QE) measurements of single photon photoemission from a Cu(111) single crystal and a Cu polycrystal photocathodes, irradiated by 150 fs-6.28 eV laser pulses, are reported over a broad range of incidence angle, both in s and p polarizations. The maximum QE (\simeq 4\times10^{-4}) for polycrystalline Cu is obtained in p polarization at an angle of incidence {\theta} = 65deg. We observe a QE enhancement in p polarization which can not be explained in terms of optical absorption, a phenomenon known as vectorial photoelectric effect. Issues concerning surface roughness and symmetry considerations are addressed. An explanation in terms of non local conductivity tensor is proposed.Comment: 3 pages, 3 figure

Above and below ground interactions in agroforestry systems

Ecological interactions between trees and crops are examined in terms of above and below ground utilizations of physical resources. Above ground interactions such as changes in light, temperature, and humidity are analyzed in terms of possible effects on understory crops. Our analysis shows that atmospheric interactions in alley cropping in the semi-arid tropics are positive but of minor importance compared with below ground interactions. Separation of below ground interactions by a shallow polythene barrier (0.5 m) indicated that competition for soil moisture is responsible for the negative interactions reported in the semi-arid tropics (SAT). Measurements of root distribution showed that roots of Leucaena leucocephala Lam. trees are abundant in the top 30 cm of the soil and the presence of a root barrier was effective in restricting lateral movement of the roots. This evidence is contrary to the assumption that trees have deep rooting systems which do not compete with crops. A secondary aim is to illustrate the contrasting problems encountered in intercropping and agroforestry systems. The importance or root studies are highlighted and the ways in which positive interactions could be achieved are investigated

Above- and below-ground interactions in a leucaena/millet alley cropping system. I. Experimental design, instrumentation and diurnal trends

Leucaena (Leucaena leucocephala (Lam.) de Wit) and pearl millet (Pennisetum glaucum (L.) R.Br.) were grown together in an alley cropping system in a semi-arid area of India. The five treatments included sole millet (SM), sole leucaena (SL) planted in double rows to form hedges with an alley width of 2.8 m, and alley cropping treatments LM5, LM6 and LM6P with alley widths of 2.8, 3.3 and 3.3 m, respectively. Millet rows within the alleys were spaced at 47 cm, giving five rows in LM5 and six rows in both LM6 and LM6P. LM6P differed from LM6 in that a vertical polythene barrier separated the root systems of leucaena and millet to a depth of 50cm. Light interception, wind speed, saturation deficit and air, soil and leaf temperatures were monitored during the 1986 and 1987 rainy seasons in treatments SM, SL and LM5. This paper describes the experimental design and instrumentation and presents representative diurnal time courses illustrating the nature of the microclimatic changes associated with alley cropping. These indicate that alley cropping altered the microclimate experienced by millet to an extent which depended on its proximity to the hedge, hedge shape and the relative size of the two components. The larger leucaena canopy in 1987 than in 1986 resulted in more substantial reductions in wind speed and incident light in the alleys of LM5 as compared with SM. Leaf and soil temperatures within the alleys tended to be warmer during the night and cooler during the day than in SM and temperature differences between rows within LM5 were related to the degree of shading by leucaena. Analysis of integrated data predicted little effect of the observed changes in saturation deficit on the productivity of millet, while thermal time analysis for 1987 suggested a 2—3 day delay in flowering for millet adjacent to the hedge as compared with sole millet