We use the extended Press-Schechter formalism to investigate the rate at which cold dark matter haloes accrete mass. We discuss the shortcomings of previous methods that have been used to compute the mass accretion histories of dark matter haloes, and present an improved method based on the N -branch merger tree algorithm of Somerville & Kolatt. We show that this method no longer suffers from i...

introduction the study area is located in the central part of the khaf- kashmar- bardaskan volcano-plotunic belt (briefly kkbb). several iocg deposits such as tanourjeh au-bearing magnetite deposit and kuh-e-zar specularite-rich au deposit have been explored in kkbb. geology, alteration, mineralization, geochemistry and fluid inclusion results in kashmar suggest the iocg type au-bearing magneti...

An analytical model is presented for the postcollapse equilibrium structure of virialized objects which condense out of a low-density cosmological background universe, either matter-dominated or flat with a cosmological constant. This generalizes the model we derived previously for an Einstein-de Sitter (EdS) universe. The model is based upon the assumption that cosmological haloes form from th...

We test the ability of the numerical action method (NAM) to recover the individual orbit histories of mass tracers in an expanding universe in a region of radius 26 hMpc, given the masses and redshift-space coordinates at the present epoch. The mass tracers are represented by dark matter haloes identified in a high resolution N -body simulation of the standard ΛCDM cosmology. Since previous tes...

We use numerical simulations in a ΛCDM cosmology to model density profiles in a set of sixteen dark matter haloes with resolutions of up to seven million particles within the virial radius. These simulations allow us to follow robustly the formation and evolution of the central cusp over a large mass range of 10 to 10 M⊙, down to approximately 0.5% of the virial radius, and from redshift 5 to t...

The standard cold dark matter (CDM) model has recently been challenged by the claim that dwarf galaxies have dark matter haloes with constant density cores, whereas CDM predicts haloes with steeply cusped density distributions. Consequently, numerous alternative dark matter candidates have recently been proposed. In this paper, we scrutinize the observational evidence for the incongruity betwee...

Shales are defined as fine-grained terrigenous sediments and rocks that contain 50% or more of terrigenous, and generally argillaceous, clastic components less than 0.062 mm in size. In the shales, clay-size components often dominate their rock properties, such as density, plasticity, parting, compatibility and swelling. Generally the size boundary between clay and silt is 4μm, but most clay mi...

traditions and manners of nuba is part of egyptian’s culture which is emerged in novelists’ works of nuba in various ways and most of the times they have been denied and objected; because ignorance and prejudice govern them, is routed in their culture and except in very few cases, they never change. the novel “playing over nuba mountains” by edris ali is one of the novels which is clearly analy...

Chemical weathering indices are commonly used for characterizing weathering profiles by incorporating bulk major element oxide chemishy inlo a single metric for each sample. Generally, on homogeneous parent rocks, weathering indices change systematically with depth. However, the weathering of heterogeneous metamorphic rocks confounds the relationship between weathering index and depth. In this ...