The analysis of solar models: Neutrinos and oscillations

Tests of solar neutrino flux and solar oscillation frequencies were used to assess standard stellar structure theory. Standard and non-standard solar models are enumerated and discussed. The field of solar seismology, wherein the solar interior is studied from the measurement of solar oscillations, is introduced

Molecular footprint of drug-selective pressure in a human immunodeficiency virus transmission chain

Known human immunodeficiency virus (HIV) transmission histories are invaluable models for investigating the evolutionary and transmission dynamics of the virus and to assess the accuracy of phylogenetic reconstructions. Here we have characterized an HIV-1 transmission chain consisting of nine infected patients, almost all of whom were treated with antiviral drugs at later stages of infection. Partial pol and env gp41 regions of the HIV genome were directly sequenced from plasma viral RNA for at least one sample from each patient. Phylogenetic analyses in pol using likelihood methods inferred an evolutionary history not fully compatible with the known transmission history. This could be attributed to parallel evolution of drug resistance mutations resulting in the incorrect clustering of multidrug-resistant virus. On the other hand, a fully compatible phylogenetic tree was reconstructed from the env sequences. We were able to identify and quantify the molecular footprint of drug-selective pressure in pol using maximum likelihood inference under different codon substitution models. An increased fixation rate of mutations in the HIV population of the multidrug-resistant patient was demonstrated using molecular clock modeling. We show that molecular evolutionary analyses, guided by a known transmission history, can reveal the presence of confounding factors like natural selection and caution should be taken when accurate descriptions of HIV evolution are required.status: publishe

High resolution study of associated C IV absorption systems in NGC 5548

We present the results of a careful analysis of associated absorption systems toward NGC 5548. Most of the well resolved narrow components in the associated system, defined by the Lyman alpha, C IV and N V profiles, show velocity separation similar (to within 10~\kms) to the C IV doublet splitting. We estimate the chance probability of occurrence of such pairs with velocity separation equal to C IV doublet splitting to be $6\times10^{-3}$. Thus it is more likely that most of the narrow components are line-locked with C IV doublet splitting. This will mean that the radiative acceleration plays an important role in the kinematics of the absorbing clouds. We build grids of photoionization models and estimate the radiative acceleration due to all possible bound-bound transitions. We show that the clouds producing absorption have densities less than $10^9 cm^{-3}$, and are in the outer regions of the broad emission line region (BLR). We note that the clouds which are line-locked cannot produce appreciable optical depths of O VII and O VIII, and hence cannot be responsible for the observed ionized edges, in the soft X-ray. We discuss the implications of the presence of optically thin clouds in the outer regions of the BLR to the models of broad emission lines.Comment: 21 pages, latex (aasms4 style), incluedes 4 ps figures. To appear in Astrophysical Journa

Modeling Variable Emission Lines in AGNs: Method and Application to NGC 5548

We present a new scheme for modeling the broad line region in active galactic nuclei (AGNs). It involves photoionization calculations of a large number of clouds, in several pre-determined geometries, and a comparison of the calculated line intensities with observed emission line light curves. Fitting several observed light curves simultaneously provides strong constraints on model parameters such as the run of density and column density across the nucleus, the shape of the ionizing continuum, and the radial distribution of the emission line clouds. When applying the model to the Seyfert 1 galaxy NGC 5548, we were able to reconstruct the light curves of four ultraviolet emission-lines, in time and in absolute flux. This has not been achieved by any previous work. We argue that the Balmer lines light curves, and possibly also the MgII2798 light curve, cannot be tested in this scheme because of the limitations of present-day photoionization codes. Our fit procedure can be used to rule out models where the particle density scales as r^{-2}, where r is the distance from the central source. The best models are those where the density scales as r^{-1} or r^{-1.5}. We can place a lower limit on the column density at a distance of 1 ld, of N_{col}(r=1) >~ 10^{23} cm^{-2} and limit the particle density to be in the range of 10^{12.5}>N(r=1)>10^{11} cm^{-3}. We have also tested the idea that the spectral energy distribution (SED) of the ionizing continuum is changing with continuum luminosity. None of the variable-shape SED tried resulted in real improvement over a constant SED case although models with harder continuum during phases of higher luminosity seem to fit better the observed spectrum. Reddening and/or different composition seem to play a minor role, at least to the extent tested in this work.Comment: 12 pages, including 9 embedded EPS figures, accepted for publication in Ap

Los hongos de colombia - vii: leotiaceae - iv: hymenoscyphus caudatus and related species from colombia and adjacent regions

The present paper redescribes and illustrates five common species of Hymenoscyphus, H. caudatus, H. serotinus, H. affin. scutulus, H. Iasiopodtum  and amp; H.sclerogenus, from Colombia and adjacent regions in South America.  Emphasis is given to discussions of anatomical and morphological variability and host specificity of the species included.  Inoperculate Discomycetes are generally small Ascomycetes producing an apothecium as their sexual fruiting structure. The largest order, the Helotiales, contains 5 families: Dermateaceae, Hyaloscyphaceae, Orbiliaceae, Sclerotiniaceae and Leotiaceae, In recent years there have been several monographic and submonographic studies on selected genera within these families, but no definitive studies on the principal family, Leotiaceae (previously referred to as the Helotiaceae), has been prepared. These studies have resulted in a better understanding of some of the family limits, but most of the generic limits still remain vague and confused. This is especially true for Hymenoscyphus (previously referred to by most workers as Helotium), which for decades has been the depository for small Discomycetes of uncertain affinities.  White (1942, 1942-a, 1943, 1944) began to work systematically through the species of Hymenoscyphus and to bring order out of the existing chaos. His carefully prepared descriptions, meticulously drawn illustrations, and long  synonymies were the real important contribution to the understanding of the genus. The most recent attempts to studyHymenoscyphus have been by Dennis, who summarized his works in 1964 (Dennis, 1964). However, as Dennis himself points out, he was unable to come to a sound understanding and arrangement of the species because of the extent of the problems, and the resulting treatment is rather artificial. He relied heavily upon substrate and geographical relations, rather than true morphological similarities. We agree with Dennis, that this has resulted in the separation of closely related taxa and an "unnecessary proliferation of names".  Although Dennis contributions were extraordinary in terms of the number of described species he examined and in his literature searches, he did not have at his disposal necessary tropical collections for a complete comprehension of the individual species and/or the entire genus. Further, as pointed out by Dumont (1976), because of limited collections Dennis was unable to understand the full morphological and geographical variation of certain species and recognized several taxa, when in the final analysis only one existed. Many of these deficiencies are apparent in his monumental work on "The Fungus Flora of Venezuela and Adjacent Countries" (Dennis, 1970).  InHymenoscyphus for example, he included only seven species (in his 1964 treatment he included more than 70 species for the world), and of these three, H. crocatus , H. caracassensis and H.atrosubiculatum have been removed from the genus by Dumont (1974) and Dumont and Pal (1978). Arendholz (1979) has recently provided a very important contribution to the understanding of several species of leaf inhabiting species ofHymenoscyphus. Again, as with previous workers, his work stressed temperate collections and temperate species. The purpose of the present study is to report the findings of some of our tropical collecting, to expand the understanding of five species of Hymenoscyphus which appear to be common in northern South America, to discuss the morphological variability observed, and to comment on the host or substrate specificity (or lack of it) within certain taxa.  The materials and methods used during these studies are the same as those reported by Dumont (1972). The following is a key to the five species   reported herein.The present paper redescribes and illustrates five common species of Hymenoscyphus, H. caudatus, H. serotinus, H. affin. scutulus, H. Iasiopodtum  and amp; H. sclerogenus, from Colombia and adjacent regions in South America.  Emphasis is given to discussions of anatomical and morphological variability and host specificity of the species included.  Inoperculate Discomycetes are generally small Ascomycetes producing an apothecium as their sexual fruiting structure. The largest order, the Helotiales, contains 5 families: Dermateaceae, Hyaloscyphaceae, Orbiliaceae, Sclerotiniaceae and Leotiaceae, In recent years there have been several monographic and submonographic studies on selected genera within these families, but no definitive studies on the principal family, Leotiaceae (previously referred to as the Helotiaceae), has been prepared. These studies have resulted in a better understanding of some of the family limits, but most of the generic limits still remain vague and confused. This is especially true for Hymenoscyphus (previously referred to by most workers as Helotium), which for decades has been the depository for small Discomycetes of uncertain affinities.  White (1942, 1942-a, 1943, 1944) began to work systematically through the species of Hymenoscyphus and to bring order out of the existing chaos. His carefully prepared descriptions, meticulously drawn illustrations, and long  synonymies were the real important contribution to the understanding of the genus. The most recent attempts to study Hymenoscyphus have been by Dennis, who summarized his works in 1964 (Dennis, 1964). However, as Dennis himself points out, he was unable to come to a sound understanding and arrangement of the species because of the extent of the problems, and the resulting treatment is rather artificial. He relied heavily upon substrate and geographical relations, rather than true morphological similarities. We agree with Dennis, that this has resulted in the separation of closely related taxa and an "unnecessary proliferation of names".  Although Dennis contributions were extraordinary in terms of the number of described species he examined and in his literature searches, he did not have at his disposal necessary tropical collections for a complete comprehension of the individual species and/or the entire genus. Further, as pointed out by Dumont (1976), because of limited collections Dennis was unable to understand the full morphological and geographical variation of certain species and recognized several taxa, when in the final analysis only one existed. Many of these deficiencies are apparent in his monumental work on "The Fungus Flora of Venezuela and Adjacent Countries" (Dennis, 1970).  In Hymenoscyphus for example, he included only seven species (in his 1964 treatment he included more than 70 species for the world), and of these three, H. crocatus , H. caracassensis and H. atrosubiculatum have been removed from the genus by Dumont (1974) and Dumont and Pal (1978). Arendholz (1979) has recently provided a very important contribution to the understanding of several species of leaf inhabiting species of Hymenoscyphus. Again, as with previous workers, his work stressed temperate collections and temperate species. The purpose of the present study is to report the findings of some of our tropical collecting, to expand the understanding of five species of Hymenoscyphus which appear to be common in northern South America, to discuss the morphological variability observed, and to comment on the host or substrate specificity (or lack of it) within certain taxa.  The materials and methods used during these studies are the same as those reported by Dumont (1972). The following is a key to the five species   reported herein

Radar Detection of High Concentrations of Ice Particles - Methodology and Preliminary Flight Test Results

High Ice Water Content (HIWC) has been identified as a primary causal factor in numerous engine events over the past two decades. Previous attempts to develop a remote detection process utilizing modern commercial radars have failed to produce reliable results. This paper discusses the reasons for previous failures and describes a new technique that has shown very encouraging accuracy and range performance without the need for any hardware modifications to industrys current radar designs. The performance of this new process was evaluated during the joint NASA/FAA HIWC RADAR II Flight Campaign in August of 2018. Results from that evaluation are discussed, along with the potential for commercial application, and development of minimum operational performance standards for a future commercial radar product

On the Origin of Broad Fe K alpha and Hi H alpha Lines in AGN

We examine the properties of the Fe emission lines that arise near 6.4 keV in the ASCA spectra of AGN. Our emphasis is on the Seyfert 1 galaxies where broad and apparently complex Fe K alpha emission is observed. We consider various origins for the line but focus on the pros and cons for line emitting accretion disk models. We develop a simple model of an illuminated disk capable of producing both X-ray and optical lines from a disk. The model is able to reproduce the observed Fe K alpha FWHM ratio as well as the radii of maximum emissivity implied by the profile redshifts. The overall profile shapes however do not fit well the predictions of our disk illumination model nor do we derive always consistent disk inclinations for the two lines. We conclude that the evidence for and against an accretion disk origin for the Fe K alpha emission is equal at best. The bulk of the data requires a very disparate set of line fits which shed little light on a coherent physical model. We briefly consider alternatives to disk emission models and show that a simple bicone model can reproduce the FE line profiles equally well.Comment: 29 pages, 6 tables, 6 figures. Submitted for publication in the Astrophysical Journal part

Average UV Quasar Spectra in the Context of Eigenvector 1: A Baldwin Effect Governed by Eddington Ratio?

We present composite UV spectra for low redshift Type 1 AGN binned to exploit the information content of the Eigenvector 1 (E1) parameter space. Composite spectra allow a decomposition of the CIV1549 line profile - one of the strongest high-ionization lines. The simplest CIV decomposition into narrow (NLR), broad (BLR) and very broad (VBLR) components suggests that different components have an analog in Hb with two major exceptions. VBLR emission is seen only in population B (FWHM(Hb)>4000 km/s) sources. A blue shifted/asymmetric BLR component is seen only in pop. A (FWHM(Hb)<4000 km/s) HIL such as CIV. The blueshifted component is thought to arise in a wind or outflow. Our analysis suggests that such a wind can only be produced in pop. A (almost all radio-quiet) sources where the accretion rate is relatively high. Comparison between broad UV lines in radio-loud (RL) and radio-quiet (RQ) sources shows few significant differences. Clear evidence is found for a narrow CIV component in most radio-loud sources. We find also some indirect indications that the black hole (BH) spin, rather than BH mass or accretion rate is a key trigger in determining whether an object will be RL or RQ. We find a ten-fold decrease in EW CIV with Eddington ratio (decreasing from ~1 to \~0.01) while NV shows no change. These trends suggest a luminosity-independent "Baldwin effect" where the physical driver may be the Eddington ratio.Comment: 39 pages, 6 figures. To appear in Ap

Tri-axial Octupole Deformations and Shell Structure

Manifestations of pronounced shell effects are discovered when adding nonaxial octupole deformations to a harmonic oscillator model. The degeneracies of the quantum spectra are in a good agreement with the corresponding main periodic orbits and winding number ratios which are found by classical analysis.Comment: 10 pages, Latex, 4 postscript figures, to appear in JETP Letter