588 research outputs found

    Increased concentration of an apparently identical cellular protein in cells transformed by either Abelson murine leukemia virus or other transforming agents

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    Abelson murine leukemia virus (A-MuLV)-transformed cells, simian virus 40 (SV40)-transformed cells, and chemically transformed cells all have increased levels of a 50,000-molecular-weight host cell protein. The protein was detected with sera raised to the A-MuLV-transformed and chemically transformed cells and was tightly bound to T-antigen in extracts of SV40-transformed cells. Partial protease digests showed that the proteins from all three sources were indistinguishable. The three proteins were phosphorylated in cells, and the linkage of phosphate to the A-MuLV-associated P50 was to a serine residue. By immunofluorescence methods, P50-related protein was found on the surface of both normal lymphoid cells and A-MuLV-transformed lymphoid cells, but cell fractionation showed that the majority of P50 was free in the cytoplasm of the transformed cells. Immunofluorescence also showed that P50 was found in granules in the cytoplasm of both untransformed and SV40-transformed fibroblasts. Other cells gave indistinct patterns. Cocapping experiments showed that the A-MuLV-specified P120 protein is weakly associated with the surface P50-related protein of lymphoid cells, but no association of P120 and P50 could be demonstrated by immunoprecipitation methods. Although a monoclonal antiserum to P50 was used in many of these studies, the identity of the bulk P50 protein with the molecules that are reactive at the cell surface requires further study

    Empirical Performance of the Czech and Hungarian Index Options under Jump

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    This paper analyses Czech and Hungarian index options that are traded on the Austrian Futures and Options Exchange. We find that the Poisson jump-diffusion and not the GARCH (1,1) process lends statistical support for the data description. We estimate that approximately four-fifth of 4 percent underpricing (for the Czech Index) and 18 percent overpricing (for the Hungarian Index) biases reported for the short term out-of-the-money call options can be explained by the Jump option pricing model. However, we question whether the mispricings from the jump model are operational, especially, in these emerging financial markets.Leptokurtosis, Poisson jump-diffusion, GARCH, Equity index

    Beam attenuation and chlorophyll concentration as alternative optical indices of phytoplankton biomass

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    Chlorophyll has long functioned as the prominent field metric for phytoplankton biomass, but its variability can be strongly influenced by (even dominated by) physiological shifts in intracellular pigmentation in response to changing growth conditions (light, nutrients, temperature). The particulate beam attenuation coefficient (cp) may offer an alternative optical measure of phytoplankton biomass that is readily assessed in situ and relatively insensitive to changes in intracellular pigment content. Unlike chlorophyll, however, cp is not uniquely associated with phytoplankton and varies as well with changes in inorganic, detrital, and heterotrophic particles. In open ocean environments, particles in the size range of ∼0.5 to 20 μm (i.e., within the phytoplankton size domain) dominate cp. Multiple field studies have indicated that the ratio of cp to chlorophyll (i.e., c*p) registers first-order changes in algal physiology, suggesting that cp covaries with phytoplankton carbon biomass. Here we use approximately 10,000 measurements of cp and fluorescence-based chlorophyll estimates (ChlFl) to evaluate the correspondence between these two phytoplankton biomass proxies. Our study focuses on a region of the eastern equatorial Pacific where mixed layer growth conditions are relatively homogeneous, thereby constraining phytoplankton chlorophyll:carbon ratios and allowing chlorophyll to function as a reliable measure of phytoplankton biomass. Over our 6600 km transect, cp was exceptionally well correlated with ChlFl (r2 = 0.93). Our results contribute additional support for cp as a viable index of phytoplankton carbon biomass in the open ocean

    Secretly Eccentric: The Giant Planet and Activity Cycle of GJ 328

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    We announce the discovery of a ~2 Jupiter-mass planet in an eccentric 11-year orbit around the K7/M0 dwarf GJ 328. Our result is based on 10 years' worth of radial velocity (RV) data from the Hobby-Eberly and Harlan J. Smith telescopes at McDonald Observatory, and from the Keck Telescope at Mauna Kea. Our analysis of GJ 328's magnetic activity via the Na I D features reveals a long-period stellar activity cycle, which creates an additional signal in the star's RV curve with amplitude 6-10 m/s. After correcting for this stellar RV contribution, we see that the orbit of the planet is more eccentric than suggested by the raw RV data. GJ 328b is currently the most massive, longest-period planet discovered around a low-mass dwarf.Comment: Accepted for publication in Ap

    Consumption Based Capital Asset Pricing and the Austrian Stock Exchange

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    Abstract: Using data from the Vienna Stock Exchange we investigate three different types of consumption based capital asset pricing models: the well known two state model of Mehra and Prescott, the model of Rietz, which includes also a crash state, and an own four state model. The aim of this Vienna Stock Exchange during the 1980s into account. For all the models we calculate the risk premium in order to see whether the models could explain the empirically observed risk premium. For the calculation of risk premia we use estimators generated by the General Method of Moments.

    An m sin i = 24 Earth Mass Planetary Companion To The Nearby M Dwarf GJ 176

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    We report the detection of a planetary companion with a minimum mass of m sin i = 0.0771 M_Jup = 24.5 M_Earth to the nearby (d = 9.4 pc) M2.5V star GJ 176. The star was observed as part of our M dwarf planet search at the Hobby-Eberly Telescope (HET). The detection is based on 5 years of high-precision differential radial velocity (RV) measurements using the High-Resolution-Spectrograph (HRS). The orbital period of the planet is 10.24 d. GJ 176 thus joins the small (but increasing) sample of M dwarfs hosting short-periodic planets with minimum masses in the Neptune-mass range. Low mass planets could be relatively common around M dwarfs and the current detections might represent the tip of a rocky planet population.Comment: 13 pages preprint, 3 figures, submitted to Ap
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