Method of stabilizing flueric vortex valves and vortex amplifiers

Inducing losses in the vortex chamber of vortex valves and vortex amplifiers resolves the problem of unstable operation caused by a sufficiently large positive feedback. Induced losses also reduce pressure gain and throttling range of vortex pressure amplifier

Scanning electron microscopy of Conidia of Trichoderma Stromaticum, a biocontrol agent of witches broom disease of cocoa.

Estudos morfológicos de conídios de Trichoderma harzianun, um agente de biocontrole da vassoura-de-bruxa do cacaueiro, foram feitos sob microscopia eletrônica de varredura com emissão de campo. Características da superfície de conídios do fungo mostraram ser rugosas quando observadas em alta maginificação; fato esse impossível de ser visualizado por microscopia ótica. Também foram observados, com freqüência, massas de conídios completamente envolvidos por material mucilaginoso e detalhes de células ramificadas dicotomicamente que formam as pústulas

Angular Momentum Profiles of Warm Dark Matter Halos

We compare the specific angular momentum profiles of virialized dark halos in cold dark matter (CDM) and warm dark matter (WDM) models using high-resolution dissipationless simulations. The simulations were initialized using the same set of modes, except on small scales, where the power was suppressed in WDM below the filtering length. Remarkably, WDM as well as CDM halos are well-described by the two-parameter angular momentum profile of Bullock et al. (2001), even though the halo masses are below the filtering scale of the WDM. Although the best-fit shape parameters change quantitatively for individual halos in the two simulations, we find no systematic variation in profile shapes as a function of the dark matter type. The scatter in shape parameters is significantly smaller for the WDM halos, suggesting that substructure and/or merging history plays a role producing scatter about the mean angular momentum distribution, but that the average angular momentum profiles of halos originate from larger-scale phenomena or a mechanism associated with the virialization process. The known mismatch between the angular momentum distributions of dark halos and disk galaxies is therefore present in WDM as well as CDM models. Our WDM halos tend to have a less coherent (more misaligned) angular momentum structure and smaller spin parameters than do their CDM counterparts, although we caution that this result is based on a small number of halos.Comment: 5 pages, 1 figure, Submitted to ApJ

The Barn Owl as a Red-Winged-Blackbird Predator in Northwestern Ohio

Author Institution: Department of Biology, Bowling Green State University, Bowling Green, Ohi

Caractéristiques de l'oestrus chez les femelles N'dama et Jersiaises au Sénégal après maîtrise du cycle sexuel par le norgestomet

Le but du présent travail a été d'étudier les paramètres chronologiques des chaleurs après maîtrise du cycle sexuel par l'implantation d'un progestagène de synthèse chez des vaches (#Bos taurus#) de race africaine (N'Dama, n = 91) et européenne (Jerseyaise, n = 31) au Sénégal. Deux lots de 91 vaches N'Dama et 31 Jerseyaises issues de 4 troupeaux différents et de conduites zootechniques distinctes ont été l'objet de tels traitements. Un implant sous-cutané de norgestomet a été posé pour une durée de 9 jours, en parallèle avec l'injection d'un analogue de prostaglandine F2 alpha, 2 jours avant le retrait. L'observation continue des chaleurs a débuté 24 h après le retrait des implants et s'est poursuivie pendant 48 h. Les résultats suivants ont été observés : les chaleurs avaient une tendance d'apparition nocturne chez les N'Dama et diurne chez les Jerseyaises ; chez les N'Dama et chez les Jerseyaises, le taux de synchronisation des chaleurs, défini par observation directe, était respectivement de 97,8 et 100 p. 100 ; l'intervalle moyen entre le retrait des implants et le début des chaleurs était respectivement de 36 et 35 h ; la durée des chaleurs était respectivement de 11 h 15 et 13 h, et 41,6 p. 100 des vaches, essentiellement les N'Dama, ont présenté des chaleurs anovulatoires. Les chaleurs étaient bien perceptibles à condition de les observer la nuit. (Résumé d'auteur

Star Formation, Supernovae Feedback and the Angular Momentum Problem in Numerical CDM Cosmogony: Half Way There?

We present a smoothed particle hydrodynamic (SPH) simulation that reproduces a galaxy that is a moderate facsimile of those observed. The primary failing point of previous simulations of disk formation, namely excessive transport of angular momentum from gas to dark matter, is ameliorated by the inclusion of a supernova feedback algorithm that allows energy to persist in the model ISM for a period corresponding to the lifetime of stellar associations. The inclusion of feedback leads to a disk at a redshift $z=0.52$, with a specific angular momentum content within 10% of the value required to fit observations. An exponential fit to the disk baryon surface density gives a scale length within 17% of the theoretical value. Runs without feedback, with or without star formation, exhibit the drastic angular momentum transport observed elsewhere.Comment: 4 pages, 3 figures, accepted for publication in ApJ Letter

Star Formation, Metallicity and Dust Properties Derived from the SAPM Galaxy Survey Spectra

We have derived star formation rates (SFRs), gas-phase oxygen abundances and effective dust absorption optical depths for a sample of galaxies drawn from the Stromlo-APM redshift survey using the new Charlot and Longhetti (2001; CL01) models, which provide a physically consistent description of the effects of stars, gas and dust on the integrated spectra of galaxies. Our sample consists of 705 galaxies with measurements of the fluxes and equivalent widths of Halpha, [OII], and one or both of [NII] and [SII]. For a subset of the galaxies, 60 and 100 micron IRAS fluxes are available. We compare the star formation rates derived using the models with those derived using standard estimators based on the Halpha, the [OII] and the far-infrared luminosities of the galaxies. The CL01 SFR estimates agree well with those derived from the IRAS fluxes, but are typically a factor of ~3 higher than those derived from the Halpha or the [OII] fluxes, even after the usual mean attenuation correction of A_Halpha=1 mag is applied to the data. We show that the reason for this discrepancy is that the standard Halpha estimator neglects the absorption of ionizing photons by dust in HII regions and the contamination of Halpha emission by stellar absorption. We also use our sample to study variations in star formation and metallicity as a function of galaxy absolute bJ magnitude. For this sample, the star formation rate per unit bJ luminosity is independent of magnitude. The gas-phase oxygen abundance does increase with bJ luminosity, although the scatter in metallicity at fixed magnitude is large.Comment: 17 pages, 8 figures, accepted for publication in MNRA

GMRT detection of HI 21 cm associated absorption towards the z=1.2 red quasar 3C 190

We report the GMRT detection of associated HI 21 cm-line absorption in the z=1.1946 red quasar 3C 190. Most of the absorption is blue-shifted with respect to the systemic redshift. The absorption, at $\sim$ 647.7 MHz, is broad and complex, spanning a velocity width of $\sim$ 600 \kms. Since the core is self-absorbed at this frequency, the absorption is most likely towards the hotspots. Comparison of the radio and deep optical images reveal linear filaments in the optical which overlap with the brighter radio jet towards the south-west. We therefore suggest that most of the HI 21 cm-line absorption could be occurring in the atomic gas shocked by the south-west jet.Comment: 8 pages, 1 fugure. To appear in Journal of Astrophysics and Astronom