Spatial correlation functions and the pairwise peculiar velocity dispersion of galaxies in the PSCz survey: implications for the galaxy biasing in cold dark matter models

We report on the measurement of the two-point correlation function, and the pairwise peculiar velocity of galaxies in the IRAS PSCz survey. We compute these statistics first in redshift space, and then obtain the projected functions which have simple relations to the real-space correlation functions on the basis of the method developed earlier in analyzing the Las Campanas Redshift Survey (LCRS) by Jing, Mo, & B\"orner (1998). We find that the real space two-point correlation function can be fitted to a power law $\xi(r) = (r_0/r)^{\gamma}$ with $\gamma=1.69$ and r_0=3.70 \mpc. The pairwise peculiar velocity dispersion $\sigma_{12}(r_p)$ is close to 400 \kms at r_p=3\mpc and decreases to about 150 \kms at r_p \approx 0.2 \mpc. These values are significantly lower than those obtained from the LCRS. In order to understand the implications of those measurements on the galaxy biasing, we construct mock samples for a low density spatially-flat cold dark matter model ($\Omega_0 = 0.3$, $\lambda_0=0.7$, $\Gamma=0.2$, $\sigma_8=1$) using a set of high-resolution N-body simulations. Applying a stronger cluster-underweight biasing ($\propto M^{-0.25}$) than for the LCRS ($\propto M^{-0.08}$), we are able to reproduce these observational data, except for the strong decrease of the pairwise peculiar velocity at small separations. This is qualitatively ascribed to the different morphological mixture of galaxies in the two catalogues. Disk-dominated galaxy samples drawn from the theoretically constructed GIF catalog yield results rather similar to our mock samples with the simple cluster-underweight biasing.Comment: accepted for publication in ApJ; 24 pages with 9 figure

The Nature of Dark Matter

The observed strong dark-to-luminous matter coupling suggests the existence of a some functional relation between visible and DM sources which leads to biased Einstein equations. We show that such a bias appears in the case when the topological structure of the actual Universe at very large distances does not match properly that of the Friedman space. We introduce a bias operator $\rho_{DM} = B \rho_{vis}$ and show that the simple bias function $b \~1/r^{2}$ (the kernel of $B$) allows to account for all the variety of observed DM halos in astrophysical systems. In galaxies such a bias forms the cored DM distribution with the radius $R_{C}\sim R_{opt}$ (which explains the recently observed strong correlation between $R_{C}$ and $R_{opt}$), while for a point source it produces the logarithmic correction to the Newton's potential (which explains the observed flat rotation curves in spirals). Finally, we show that in the theory suggested the galaxy formation process leads to a specific variation with time of all interaction constants and, in particular, of the fine structure constant.Comment: 12 pages, essential revisio

Zielorientiertes Wissensmanagement in Bauunternehmen

ISSN:1660-4504ISSN:0036-730

Numerical Computation of Two Dimensional Wind Accretion of Isothermal Gas

. A new numerical algorithm for calculating isothermal wind accretion flows has been developed and is applied here to the analysis of the hydrodynamics of two-dimensional plane symmetric accretion flows in wind-fed sources. Polar coordinates are used to ensure fine resolution near the object. It is found that a thin accretion column is formed which shows wave-like oscillations. Small accretion disks are formed temporarily around the object. Mass accretion rate and angular momentum accretion rate exhibit quasi-periodic oscillations. The amplitudes of the oscillations depend on the size of the inner boundary, the number of grid points and the method of calculation. For a smaller size of the inner boundary, finer grids and more accurate numerical schemes, the amplitudes of the oscillation become larger. Key words: Accretion, accretion disks -- Hydrodynamics -- Instabilities -- Shock waves -- Methods: numerical -- pulsars: general 1. Introduction Wind-fed accretion by a compact gravitatin..

Novel functional profiling approach combining reverse phase protein microarrays and human 3-D ex vivo tissue cultures: expression of apoptosis-related proteins in human colon cancer

Cancer is caused by a complex pattern of molecular perturbations. To understand the biology of cancer, it is thus important to look at the activation state of key proteins and signaling networks. The limited amount of available sample material from patients and the complexity of protein expression patterns make the use of traditional protein analysis methods particularly difficult. In addition, the only approach that is currently available for performing functional studies is the use of serial biopsies, which is limited by ethical constraints and patient acceptance. The goal of this work was to establish a 3-D ex vivo culture technique in combination with reverse-phase protein microarrays (RPPM) as a novel experimental tool for use in cancer research. The RPPM platform allows the parallel profiling of large numbers of protein analytes to determine their relative abundance and activation level. Cancer tissue and the respective corresponding normal tissue controls from patients with colorectal cancer were cultured ex vivo. At various time points, the cultured samples were processed into lysates and analyzed on RPPM to assess the expression of carcinoembryonic antigen (CEA) and 24 proteins involved in the regulation of apoptosis. The methodology displayed good robustness and low system noise. As a proof of concept, CEA expression was significantly higher in tumor compared with normal tissue (p<0.0001). The caspase 9 expression signal was lower in tumor tissue than in normal tissue (p<0.001). Cleaved Caspase 8 (p=0.014), Bad (p=0.007), Bim (p=0.007), p73 (p=0.005), PARP (p<0.001), and cleaved PARP (p=0.007) were differentially expressed in normal liver and normal colon tissue. We demonstrate here the feasibility of using RPPM technology with 3-D ex vivo cultured samples. This approach is useful for investigating complex patterns of protein expression and modification over time. It should allow functional proteomics in patient samples with various applications such as pharmacodynamic analyses in drug development

Pankreaskarzinom

Das Pankreaskarzinom (Adenokarzinom des Pankreas) steht bei Frauen an sechster, bei Männern an zehnter Stelle der häufigsten, neuaufgetretenen Krebserkrankungen. Das mittlere Erkrankungsalter liegt zwischen 70-75 Jahren, Personen mit genetischer oder erworbener Belastung können schon im frühen Erwachsenenalter erkranken. Etwa 70% der Karzinome sind im Pankreaskopf lokalisiert. Bisher gibt es keine wirksamen Früherkennungsmaßnahmen, auch nicht bei Risikopersonen. Therapie und Prognose des Pankreaskarzinoms sind abhängig vom Krankheitsstadium bei Erstdiagnose. Beim lokal begrenzten Pankreaskarzinom steht die Operation an erster Stelle. Eine adjuvante Chemotherapie verbessert die Überlebensraten. Bei Patienten mit lokal fortgeschrittenem Pankreaskarzinom ohne Fernmetastasen kann versucht werden, durch eine primär medikamentöse Tumortherapie den Status einer resektablen Erkrankung zu erreichen. Bei Patienten mit Fernmetastasen hat die Therapie einen palliativen Anspruch mit den Zielen der Linderung von Symptomen und der Verlängerung der Überlebenszeit. In der medikamentösen Therapie sind vor allem Zytostatika wirksam. Das Adenokarzinom des Pankreas gehört zu den Malignomen mit der höchsten krebsspezifischen Mortalität. Die Fortschritte in der Diagnostik und Therapie des Pankreaskarzinoms haben bisher nur in kleinen Subgruppen zu einer Senkung der Sterblichkeit geführt