Towards Understanding The B[e] Phenomenon: IV. Modeling of IRAS 00470+6429

FS CMa type stars are a recently described group of objects with the B[e] phenomenon that exhibit strong emission-line spectra and strong IR excesses. In this paper we report the first attempt for a detailed modeling of IRAS 00470+6429, for which we have the best set of observations. Our modeling is based on two key assumptions: the star has a main-sequence luminosity for its spectral type (B2) and the circumstellar envelope is bimodal, composed of a slowly outflowing disk-like wind and a fast polar wind. Both outflows are assumed to be purely radial. We adopt a novel approach to describe the dust formation site in the wind that employs timescale arguments for grain condensation and a self-consistent solution for the dust destruction surface. With the above assumptions we were able to reproduce satisfactorily many observational properties of IRAS 00470+6429, including the H line profiles and the overall shape of the spectral energy distribution. Our adopted recipe for dust formation proved successful in reproducing the correct amount of dust formed in the circumstellar envelope. Possible shortcomings of our model, as well as suggestions for future improvements, are discussed.Comment: 11 pages, 7 figures, accepted for publication in The Astrophysical Journa

Stagnation and Infall of Dense Clumps in the Stellar Wind of tau Scorpii

Observations of the B0.2V star tau Scorpii have revealed unusual stellar wind characteristics: red-shifted absorption in the far-ultraviolet O VI resonance doublet up to +250 km/s, and extremely hard X-ray emission implying gas at temperatures in excess of 10^7 K. We describe a phenomenological model to explain these properties. We assume the wind of tau Sco consists of two components: ambient gas in which denser clumps are embedded. The clumps are optically thick in the UV resonance lines primarily responsible for accelerating the ambient wind. The reduced acceleration causes the clumps to slow and even infall, all the while being confined by the ram pressure of the outflowing ambient wind. We calculate detailed trajectories of the clumps in the ambient stellar wind, accounting for a line radiation driving force and the momentum deposited by the ambient wind in the form of drag. We show these clumps will fall back towards the star with velocities of several hundred km/sec for a broad range of initial conditions. The infalling clumps produce X-ray emitting plasmas with temperatures in excess of (1-6)x10^7 K in bow shocks at their leading edge. The infalling material explains the peculiar red-shifted absorption wings seen in the O VI doublet. The required mass loss in clumps is 3% - 30% ofthe total mass loss rate. The model developed here can be generally applied to line-driven outflows with clumps or density irregularities. (Abstract Abridged)Comment: To appear in the ApJ (1 May 2000). 24 pages, including 6 embedded figure

Polarization and kinematics in Cygnus A

From optical spectropolarimetry of Cygnus A we conclude that the scattering medium in the ionization cones in Cygnus A is moving outward at a speed of 170+-34 km/s, and that the required momentum can be supplied by the radiation pressure of an average quasar. Such a process could produce a structure resembling the observed ionization cones, which are thought to result from shadowing by a circumnuclear dust torus. We detect a polarized red wing in the [O III] emission lines arising from the central kiloparsec of Cygnus A. This wing is consistent with line emission created close to the boundary of the broad-line region.Comment: 5 pages, accepted for publication in MNRAS letter

Constraining the star formation rate in the Solar neighbourhood with star clusters

This paper investigates the star formation rate (SFR) in the Solar neighbourhood. First, we build the local age distribution function (ADF) with an updated sample of 442 star clusters located at less than 1\,kpc from the Sun. Next, we define the SFR, compute the individual mass evolution of a population of artificial clusters covering the broad range of parameters observed in actual clusters, and assume 100\,\ms\ as the low-mass limit for effective cluster observation. This leads to a simulated ADF, which is compared to the low-noise Solar neighbourhood ADF. The best match corresponds to a non-constant SFR presenting two conspicuous excesses for ages $\le9$\,Myr and between 220-600\,Myr (the local starburst). The average formation rate is \bar{SFR}\approx(2500\pm500)\,\mmy, corresponding to the average surface formation rate \bar{\ssfr}\approx(790\pm160)\,\mmk. These values are consistent with the formation rate inferred from embedded clusters (ECs), but much lower (\la16%) than that implied by field stars. Both the local starburst and the recent star formation period require $SFR\sim2\times\bar{SFR}$ to be described. The simulations show that $91.2\pm2.7$ of the clusters created in the Solar neighbourhood do not survive the first 10\,Myr, which is consistent with the rate of EC dissolution.Comment: Accepted by MNRA

HIV-1 Evolutionary Patterns Associated with Metastatic Kaposi's Sarcoma during AIDS.

Kaposi's sarcoma (KS) in HIV-infected individuals can have a wide range of clinical outcomes, from indolent skin tumors to a life-threatening visceral cancer. KS tumors contain endothelial-related cells and inflammatory cells that may be HIV-infected. In this study we tested if HIV evolutionary patterns distinguish KS tumor relatedness and progression. Multisite autopsies from participants who died from HIV-AIDS with KS prior to the availability of antiretroviral therapy were identified at the AIDS and Cancer Specimen Resource (ACSR). Two patients (KS1 and KS2) died predominantly from non-KS-associated disease and KS3 died due to aggressive and metastatic KS within one month of diagnosis. Skin and visceral tumor and nontumor autopsy tissues were obtained (n = 12). Single genome sequencing was used to amplify HIV RNA and DNA, which was present in all tumors. Independent HIV tumor clades in phylogenies differentiated KS1 and KS2 from KS3, whose sequences were interrelated by both phylogeny and selection. HIV compartmentalization was confirmed in KS1 and KS2 tumors; however, in KS3, no compartmentalization was observed among sampled tissues. While the sample size is small, the HIV evolutionary patterns observed in all patients suggest an interplay between tumor cells and HIV-infected cells which provides a selective advantage and could promote KS progression

Hot Die Forming - Flat (HDF-F^Al):An innovative hot forming technology for extreme lightweight in aluminum sheet alloys

Aluminum is an ideal material for light transport applications. Despite the obvious advantages in weight ratio and corrosion resistance, high strength aluminum alloys have limited formability compared to traditional steels at room temperature conditions. A solution is to combine mechanical loading with thermal component i.e. deformation at elevated temperature. Currently super plastic forming and Quick Plastic Forming (QPF) is used to enhance the formability of Aluminum alloys. However, the cycle time for super plastic forming as well as for QPF is too high for mass production. An innovative and novel forming method called Hot Die Forming (HDF) has been developed to achieve high strains in high strength aluminum alloys (maximum 700 [MPa]) by heating them to Solution Heat Temperature (SHT), while keeping the cycle time suitable for large scale production. To study the feasibility and optimize the process parameters, a digital platform has been developed for simulations of HDF process. The simulation process has been automated, the user can provide tool geometries and input parameters to check the feasibility of HDF process or to optimize the parameters and die shape

Probing the Pulsar Wind in the gamma-ray Binary System PSR B1259-63/SS 2883

The spectral energy distribution from the X-ray to the very high energy regime ($>100$ GeV) has been investigated for the $\gamma$-ray binary system PSR B1259-63/SS2883 as a function of orbital phase within the framework of a simple model of a pulsar wind nebula. The emission model is based on the synchrotron radiation process for the X-ray regime and the inverse Compton scattering process boosting stellar photons from the Be star companion to the very high energy (100GeV-TeV) regime. With this model, the observed temporal behavior can, in principle, be used to probe the pulsar wind properties at the shock as a function of the orbital phase. Due to theoretical uncertainties in the detailed microphysics of the acceleration process and the conversion of magnetic energy into particle kinetic energy, the observed X-ray data for the entire orbit are fit using two different methods.Comment: 46 pages, 16 figures, accepted for publication in Ap

Astrophysical parameters of 14 open clusters projected close to the Galactic plane

Astrophysical parameters (\textit{age, reddening, distance, core and cluster radii}) of 14 open clusters (OCs) projected close to the Galactic plane are derived with 2MASS photometry. The OCs are Be 63, Be 84, Cz 6, Cz 7, Cz 12, Ru 141, Ru 144, Ru 172, FSR 101, FSR 1430, FSR 1471, FSR 162, FSR 178 and FSR 198. The OCs Be 63, Be 84, Ru 141, Ru 144, and Ru 172 are studied in more detail than in previous works, while the others have astrophysical parameters derived for the first time. The open clusters of the sample are located at $d_\odot=1.6-7.1$ kpc from the Sun and at Galactocentric distances $5.5-11.8$ kpc, with age in the range 10 Myr to 1.5 Gyr and reddening $E(B-V)$ in the range $0.19-2.56$ mag. The core and cluster radii are in the range $0.27-1.88$ pc and $2.2-11.27$ pc, respectively. Cz 6 and FSR 198 are the youngest OCs of this sample, with a population of pre-main sequence (PMS) stars, while FSR 178 is the oldest cluster.Comment: 11 pages, 14 figures - accepted by A&

Gene-modified T cells for adoptive immunotherapy of renal cell cancer maintain transgene-specific immune functions in vivo

Abstract BACKGROUND: We have treated three patients with carboxy-anhydrase-IX (CAIX) positive metastatic renal cell cancer (RCC) by adoptive transfer of autologous T-cells that had been gene-transduced to express a single-chain antibody-G250 chimeric receptor [scFv(G250)], and encountered liver toxicity necessitating adaptation of the treatment protocol. Here, we investigate whether or not the in vivo activity of the infused scFv(G250)(+) T cells is reflected by changes of selected immune parameters measured in peripheral blood. METHODS: ScFv(G250)-chimeric receptor-mediated functions of peripheral blood mononuclear cells (PBMC) obtained from three patients during and after treatment were compared to the same functions of scFv(G250)(+) T lymphocytes prior to infusion, and were correlated with plasma cytokine levels. RESULTS: Prior to infusion, scFv(G250)(+) T lymphocytes showed in vitro high levels of scFv(G250)-chimeric receptor-mediated functions such as killing of CAIX(+) RCC cell lines and cytokine production upon exposure to these cells. High levels of IFN-gamma were produced, whilst production of TNF-alpha, interleukin-4 (IL-4), IL-5 and IL-10 was variable and to lower levels, and that of IL-2 virtually absent. PBMC taken from patients during therapy showed lower levels of in vitro scFv(G250)-receptor-mediated functions as compared to pre-infusion, whilst IFN-gamma was the only detectable cytokine upon in vitro PBMC exposure to CAIX. During treatment, plasma levels of IFN-gamma increased only in the patient with the most prominent liver toxicity. IL-5 plasma levels increased transiently during treatment in all patients, which may have been triggered by the co-administration of IL-2. CONCLUSION: ScFv(G250)-receptor-mediated functions of the scFv(G250)(+) T lymphocytes are, by and large, preserved in vivo upon administration, and may be reflected by fluctuations in plasma IFN-gamma levels