Observation and modelling of main-sequence star chromospheres – XIX. FIES and FEROS observations of dM1 stars

We present 187 high-resolution spectra for 62 different M1 dwarfs from observations obtained with the FIbre-fed Echelle Spectrograph (FIES) on the Nordic Optical Telescope (NOT) and from observations with the Fibre-fed Extended Range Echelle Spectrograph (FEROS) from the European Southern Observatory (ESO) data base. We also compiled other measurements available in the literature.We observed two stars, Gl 745A and Gl 745B, with no Ca ii line core emission and Hα line equivalent widths (EWs) of only 0.171 and 0.188 Å, respectively. We also observed another very low activity M1 dwarf, Gl 63, with an Hα line EW of only 0.199 Å. These are the lowest activity M dwarfs ever observed and are of particular interest for the non-local thermodynamic equilibrium radiative transfer modelling of M1 dwarfs. Thanks to the high signal-to-noise ratio of most of our spectra, we were able to measure the Ca ii H&K full width at half-maximum (FWHM) for most of our stars. We find good correlations between the FWHM values and the mean Ca ii line EW for dM1 stars. Then the FWHM seems to saturate for dM1e stars. Our previous models of M1 dwarfs can reproduce the FWHM for dM1e stars and the most active dM1 stars, but fail to reproduce the observations of lower activity M1 dwarfs. We believe this is due to an effect of metallicity. We also investigate the dependence of the Hα line FWHM as a function of its EW. We find that the models globally agree with the observations including subwarfs, but tend to produce too narrow profiles for dM1e stars. We re-investigate the correlation between the Ca ii line mean EW and the absolute magnitude. With our new data that notably include several M1 subdwarfs, we find a slightly different and better correlation with a slope of −0.779 instead of −0.909. We also re-investigate the variations of the Hα line EW as a function of radius and find that the EW increases continuously with increasing radius. This confirms our previous finding that the level of magnetic activity in M1 dwarfs increases with the radius. For the first time, we investigate the Wilson–Bappu correlation for a given spectral type. We find a rather linear correlation for stars of absolute magnitude greater than 9.6, but below this value the FWHM seems to saturate. In fact, we show that these Wilson–Bappu type correlations are activity–FWHM correlations and are due to the diminishing column mass of the transition region with decreasing activity level

Profile of cancer patients requiring dental and oral-maxillofacial prostheses in a Brazilian subpopulation

The aim of the present study was to identify the profile of cancer patients in need of rehabilitation with dental and/or oral-maxillofacial prostheses and evaluate possible reasons for not concluding the rehabilitation process. A retrospective observati

Effect Of Host Plant On The Fecundity Of Spittlebug Deois Flavopicta Stal (homoptera: Cercopidae): Implications On Population Dynamics

The spittlebug Deois flavopicta Stal (Hom.: Cercopidae) occurs naturally on native grasses in Central Brazil in low population densities. After the introduction of African grasses, mainly of the genus Brachiaria, for cattle raising, D. flavopicta began to produce population outbreaks and became a pest. Two studies were conducted, aiming to estimate the effects of a native and an exotic host plant on the fecundity of this insect. Females of D. flavopicta maintained during the adult stage on Brachiaria ruziziensis produced more eggs and lived longer than those maintained on Axonopus marginatus (a native grass widely distributed in Brazil), independently of the host plant on which the nymphs were reared. Due to the severe damage produced by adult D. flavopicta on the host plant, the effect of insect density on its own reproductive capacity was evaluated in oviposition cages containing plants of B. ruziziensis, standardized in height and stem number. Densities of one, two, three, four and six couples with virgin females were evaluated. Population densities of three couples, equivalent to 150 adults/m2, or higher decreased insect's fecundity. These results contributed to the understanding of the mechanisms that determine low levels of spittlebug populations in the native grasses and promote population outbreaks in introduced ones.304547552Begon, M., Mortimer, M., (1986) Population Ecology: A Unified Study of Animals and Plants. 2nd Ed., , Oxford, Blackwell, 220pBerryman, A.A., The theory and classification of outbreaks (1987) Insect Outbreaks, pp. 3-28. , P. Barbosa & J.C. Schultz (eds.), New York, Academic Pres, 578pBoddey, R.M., Victoria, R.L., Estimation of biological nitrogen fixation associated with Brachiaria and Paspalum grasses using 15N labelled organic matter and fertilizer (1986) Plant Soil, 90, pp. 265-313Cavalcante, P.B., Contribuição ao estudo dos corpos silicosos das gramíneas amazônicas (1968) Botânica, 30, pp. 1-26Döbereiner, J., Pedrosa, F.O., (1987) Nitrogen-fixing Bacteria in Nonleguminous Crop Plants, , New York, Spring-Verlag, 155pFontes, E.M.G., Pires, C.S., Sujii, E.R., Mixed risk-spreading strategies and the population dynamics of a brazilian pasture pest, Deois flavopicta (Homoptera: Cercopidae) (1995) J. Econ. Entomol., 88, pp. 1256-1262Ferrufino, A., Lapointe, S.L., Host plant resistance in Brachiaria grasses to the spittlebug Zulia colombiana (1989) Entomol. Exp. Appl., 51, pp. 155-162Haukioja, E., Effects of food and predation on population dynamics (1993) Caterpillars: Ecological and Evolutionary Constraints on Foraging, pp. 425-447. , N.E. Stamp & T.M. Casey (eds.), New York, Chapman and Hall, 587pHewitt, G.B., Enviromental factors affecting spittlebug egg survival during the dry season in Central Brazil (1986) Pesq. Agropec. Bras., 21, pp. 1237-1243Hewitt, G.B., Nilakhe, S.S., Enviromental factors affecting the survival of eggs and early instar nymphs of spittlebugs Zulia entreriana and Deois flavopicta during the rainy season in central Brazil (1986) An. Soc. Entomol. Brasil, 15, pp. 61-76Klink, C.A., Effects of clipping on size and tillering of native and African grasses of Brazilian savannas (the cerrado) (1984) Oecologia, 70, pp. 365-376Kuo, J., Fox, E., MacDonald, S., (1992) Sigmastat: Statistical Software for Working Scientist. User's Manual, , San Francisco, Jandel ScientificMelo, L.A.A., Silveira Neto, S., Villa Nova, N.A., Reis, P.R., Influência de elementos climáticos sobre a população de cigarrinhas das pastagens (1984) Pesq. Agropec. Bras., 19, pp. 9-19De Menezes, M., El Khadi, M.K., Pereira, J.M., Ruiz, M.A.M., (1983) Bases para O Controle Integrado Das Cigarrinhas-das-pastagens Na Região Sudeste Da Bahia, , CEPLAC-CEPEC, Ilhéus, 33pMilanez, J.M., Parra, J.R.P., Menezes, M., Influência de alguns fatores climáticos nas flutuações populacionais de Zulia entreriana (Berg, 1879) e Deois flavopicta (Stal, 1854) nas regiões de Nova Odessa e Piracicaba, Estado de São Paulo (1981) Rev. Theobroma, 11, pp. 219-228Oomen, P.A., A population study of the spittle bugs Aeneolamia occidentalis (Walk.) and Prosapia simulans (Walk.) (Homoptera: Cercopidae) in Mexican Pangola pastures (1975) Z. Ang. Entomol., 79, pp. 225-238Pacheco, J.M., (1981) Aspectos Da Biologia e Ecologia de Deois Flavopicta (Stal, 1854) (Homoptera: Cercopidae) Na Região de São Carlos, , Tese de doutorado, UFSCa, São Paulo, 111pPires, C.S.S., Sujii, E.R., Fontes, E.M.G., Tauber, C.A., Tauber, M.J., Dry-season dormancy in eggs of Deois flavopicta (Homoptera: Cercopidae): Roles of temperature and moisture in nature (2000) Environ. Entomol., 29, pp. 714-720Pires, C.S.S., Price, P.W., Fontes, E.G., Preference performance linkage in the neotropical spittlebug Deois flavopicta, and its relation to the phylogenetic constraints hypothesis (2000) Ecol. Entomol., 25, pp. 71-80Pires, C.S.S., Price, P.W., Oliveira, R.C., Distribution of the spitttlebug Deois flavopicta (Homoptera: Cercopidae) on wild and cultivated host species (2000) An. Soc. Entomol. Brasil, 29, pp. 401-412Raven, J.A., Phytophages of xylem and phloem: A comparison of animal and plant sap-feeders (1983) Adv. Ecol. Res., 13, pp. 135-234Sanders, C.J., Knight, F.B., Natural regulation of the aphid Pterocomma populifoliae on bigtooth aspen in northern lower Michigan (1968) Ecology, 49, pp. 234-244Sendulsky, T., Labouriau, L.G., Corpos silicosos de gramíneas dos Cerrados - I (1966) An. Acad. Bras. Ciênc., 38, pp. 159-185Stoporoli-Neto, A., Pacheco, J.M., Motta, L., Pavan, C., Métodos de obtenção de ovos de cigarrinhas-das-pastagens Deois spp. (Homoptera: Cercopidae) (1985) Rev. Bras. Entomol., 29, pp. 523-533Sujii, E.R., Garcia, M.A., Fontes, E.M.G., Carvalho, V., Efeito da temperatura e umidade sobre o término diapausa de ovos e densidade populacional da cigarrinha-das-pastagens, Deois flavopicta (Stal) (Homoptera: Cercopidae) (1995) An. Soc. Entomol. Brasil, 24, pp. 465-478Sujii, E.R., (1998) Modelagem e Simulação Da Dinâmica Populacional Da Cigarrinha-das-pastagens, Deois Flavopicta (Homoptera: Cercopidae), , Tese de doutorado, Universidade Estadual de Campinas UNICAMP, Campinas, SP, 239pThompson, V., Spittlebug indicators of nitrogen-fixing plants (1994) Ecol. Entomol., 19, pp. 391-398Valério, J.R., Spittlebugs: Important pasture pests in Brazil (1988) Tymbal, 12, pp. 14-1

Staphylococcus aureus nasal colonization in Spanish children. The COSACO nationwide surveillance study

Objective: To assess the prevalence and risk factors for S. aureus and methicillin-resistant S. aureus (MRSA) nasal colonization in Spanish children. Methods: Cross-sectional study of patients <14 years from primary care centers all over Spain. Clinical data and nasal aspirates were collected from March to July 2018. Results: A total of 1876 patients were enrolled. Prevalence of S. aureus and MRSA colonization were 33% (95% CI 30.9–35.1) and 1.44% (95% CI 0.9–2), respectively. Thirtythree percent of the children (633/1876) presented chronic conditions, mainly atopic dermatitis, asthma and/or allergy (524/633). Factors associated with S. aureus colonization were age =5 years (OR 1.10, 95% CI 1.07–1.12), male sex (OR 1.43, 95% CI 1.17–1.76), urban setting (OR 1.46, 95% CI 1.08–1.97) and the presence of asthma, atopic dermatitis or allergies (OR 1.25; 95% CI: 1.093–1.43). Rural residence was the only factor associated with MRSA colonization (OR 3.62, 95% CI 1.57–8.36). MRSA was more frequently resistant than methicillin-susceptible S. aureus to ciprofloxacin [41.2% vs 2.6%; p<0.0001], clindamycin [26% vs 16.9%; p=0.39], and mupirocin [14.3% vs 6.7%; p=0.18]. None of the MRSA strains was resistant to tetracycline, fosfomycin, vancomycin or daptomycin. Conclusions: The main risk factors for S. aureus colonization in Spanish children are being above five years of age, male gender, atopic dermatitis, asthma or allergy, and residence in urban areas. MRSA colonization is low, but higher than in other European countries and is associated with rural settings

Optical absorption spectra in SrCu_2O_3 two-leg spin ladder

We calculate the phonon-assisted optical-absorption spectra in SrCu_2O_3 two-leg spin-ladder systems. The results for two models proposed for SrCu_2O_3 are compared. In the model including the effects of a cyclic four-spin interaction, the shoulder structure appears at 978 cm^{-1} and the peak appears at 1975 cm^{-1} in the spectrum for polarization of the electric field parallel to the legs. In the other model which describes a pure two-leg ladder, the peak appears around the lower edge of the spectrum at 1344 cm^{-1}. The feature can be effective in determining the proper model for SrCu_2O_3.Comment: 5 pages, 5 figures, to appear in PRB vol. 67 (2003

Bounds on masses of bulk fields in string compactifications

In string compactification on a manifold X, in addition to the string scale and the normal scales of low-energy particle physics, there is a Kaluza-Klein scale 1/R associated with the size of X. We present an argument that generic string models with low-energy supersymmetry have, after moduli stabilization, bulk fields with masses which are parametrically lighter than 1/R. We discuss the implications of these light states for anomaly mediation and gaugino mediation scenarios.Comment: 15 page

Stability of the monoclinic phase in the ferroelectric perovskite PbZr(1-x)TixO3

Recent structural studies of ferroelectric PbZr(1-x)TixO3 (PZT) with x= 0.48, have revealed a new monoclinic phase in the vicinity of the morphotropic phase boundary (MPB), previously regarded as the the boundary separating the rhombohedral and tetragonal regions of the PZT phase diagram. In the present paper, the stability region of all three phases has been established from high resolution synchrotron x-ray powder diffraction measurements on a series of highly homogeneous samples with 0.42 <=x<= 0.52. At 20K the monoclinic phase is stable in the range 0.46 <=x<= 0.51, and this range narrows as the temperature is increased. A first-order phase transition from tetragonal to rhombohedral symmetry is observed only for x= 0.45. The MPB, therefore, corresponds not to the tetragonal-rhombohedral phase boundary, but instead to the boundary between the tetragonal and monoclinic phases for 0.46 <=x<= 0.51. This result provides important insight into the close relationship between the monoclinic phase and the striking piezoelectric properties of PZT; in particular, investigations of poled samples have shown that the monoclinic distortion is the origin of the unusually high piezoelectric response of PZT.Comment: REVTeX file, 7 figures embedde

A perspective on the landscape problem

I discuss the historical roots of the landscape problem and propose criteria for its successful resolution. This provides a perspective to evaluate the possibility to solve it in several of the speculative cosmological scenarios under study including eternal inflation, cosmological natural selection and cyclic cosmologies.Comment: Invited contribution for a special issue of Foundations of Physics titled: Forty Years Of String Theory: Reflecting On the Foundations. 31 pages, no figure

A Quantitative Model of Energy Release and Heating by Time-dependent, Localized Reconnection in a Flare with a Thermal Loop-top X-ray Source

We present a quantitative model of the magnetic energy stored and then released through magnetic reconnection for a flare on 26 Feb 2004. This flare, well observed by RHESSI and TRACE, shows evidence of non-thermal electrons only for a brief, early phase. Throughout the main period of energy release there is a super-hot (T>30 MK) plasma emitting thermal bremsstrahlung atop the flare loops. Our model describes the heating and compression of such a source by localized, transient magnetic reconnection. It is a three-dimensional generalization of the Petschek model whereby Alfven-speed retraction following reconnection drives supersonic inflows parallel to the field lines, which form shocks heating, compressing, and confining a loop-top plasma plug. The confining inflows provide longer life than a freely-expanding or conductively-cooling plasma of similar size and temperature. Superposition of successive transient episodes of localized reconnection across a current sheet produces an apparently persistent, localized source of high-temperature emission. The temperature of the source decreases smoothly on a time scale consistent with observations, far longer than the cooling time of a single plug. Built from a disordered collection of small plugs, the source need not have the coherent jet-like structure predicted by steady-state reconnection models. This new model predicts temperatures and emission measure consistent with the observations of 26 Feb 2004. Furthermore, the total energy released by the flare is found to be roughly consistent with that predicted by the model. Only a small fraction of the energy released appears in the super-hot source at any one time, but roughly a quarter of the flare energy is thermalized by the reconnection shocks over the course of the flare. All energy is presumed to ultimately appear in the lower-temperature T<20 MK, post-flare loops