Nonlinear Evolution of the Genus Statistics with Zel'dovich Approximation

Evolution of genus density is calculated from Gaussian initial conditions using Zel'dovich approximation. A new approach is introduced which formulates the desired quantity in a rotationally invariant manner. It is shown that normalized genus density does not depend on the initial spectral shape but is a function of the fluctuation amplitude only.Comment: 21 pages, 6 Postscript figures, LaTe

Bias and Hierarchical Clustering

It is now well established that galaxies are biased tracers of the distribution of matter, although it is still not known what form this bias takes. In local bias models the propensity for a galaxy to form at a point depends only on the overall density of matter at that point. Hierarchical scaling arguments allow one to build a fully-specified model of the underlying distribution of matter and to explore the effects of local bias in the regime of strong clustering. Using a generating-function method developed by Bernardeau & Schaeffer (1992), we show that hierarchical models lead one directly to the conclusion that a local bias does not alter the shape of the galaxy correlation function relative to the matter correlation function on large scales. This provides an elegant extension of a result first obtained by Coles (1993) for Gaussian underlying fields and confirms the conclusions of Scherrer & Weinberg (1998) obtained using a different approach. We also argue that particularly dense regions in a hierarchical density field display a form of bias that is different from that obtained by selecting such peaks in Gaussian fields: they are themselves hierarchically distributed with scaling parameters $S_p=p^{(p-2)}$. This kind of bias is also factorizable, thus in principle furnishing a simple test of this class of models.Comment: Latex, accepted for publication in ApJL; moderate revision

Phase diagram of a dilute ferromagnet model with antiferromagnetic next-nearest-neighbor interactions

We have studied the spin ordering of a dilute classical Heisenberg model with spin concentration $x$, and with ferromagnetic nearest-neighbor interaction $J_1$ and antiferromagnetic next-nearest-neighbor interaction $J_2$. Magnetic phases at absolute zero temperature $T = 0$ are determined examining the stiffness of the ground state, and those at finite temperatures $T \neq 0$ are determined calculating the Binder parameter $g_L$ and the spin correlation length $\xi_L$. Three ordered phases appear in the $x-T$ phase diagram: (i) the ferromagnetic (FM) phase; (ii) the spin glass (SG) phase; and (iii) the mixed (M) phase of the FM and the SG. Near below the ferromagnetic threshold $x_{\rm F}$, a reentrant SG transition occurs. That is, as the temperature is decreased from a high temperature, the FM phase, the M phase and the SG phase appear successively. The magnetization which grows in the FM phase disappears in the SG phase. The SG phase is suggested to be characterized by ferromagnetic clusters. We conclude, hence, that this model could reproduce experimental phase diagrams of dilute ferromagnets Fe$_x$Au$_{1-x}$ and Eu$_x$Sr$_{1-x}$S.Comment: 9 pages, 23 figure

Distributions and Geographical Relationships of the Polygyrid Land Snails (Mollusca, Gastropoda, Polygyridae) of Arkansas

The Arkansas distributions of land mollusks of the family Polygyridae are presented based on the results of a state-wide survey and a critical review of published and unpublished locality records. Six of the 45 species previously recorded for Arkansas are excluded because they were misidentified, do not have established populations in the state, or are found only as fossils. Four others are not mapped because of a lack of recent distributional data or because the specific status of a form is unclear. There is a predominant pattern of occurrence limited to the northern, northwestern, or western parts of the state. The northwest has rock outcrops, including the limestone and dolomite outcrops of the Ozark Mountains, extensive broadleaf woodland cover, and has suffered less disturbance from agriculture than the southeast, which results in more suitable land mollusk habitats in the northwest. Secondary patterns are apparent for species that are of widespread or sporadic distribution throughout the state, or found only in the eastern part of the state. Compared to adjoining states, Arkansas has a high diversity of polygyrid snails, exceeded only by Tennessee (59 species) and Texas (40 species). The highest number of co-occurrences is between Arkansas and Missouri (94.1%) and Arkansas and Oklahoma (92.3%). Arkansas shares 36.9% of species with states that border the eastern side of the Mississippi River and 63.1% with states that border the western side of the river. These data illustrate the dominance of the Ozark/Boston Mountains fauna on Arkansas land snail distribution plus what could be regarded as a secondary mid-western element

Revised List of Arkansas Terrestrial Mollusks with Notes on the Geographic Distribution of Species

A revised list of of Arkansas terrestrial mollusks is presented, based on the authors\u27 collections, incorporating data from the scientific literature and taking into account recent changes in taxonomy and species concepts. 144 species are recorded for Arkansas, of which 127 represent the autochthonous fauna of the state. The biogeographical position of Arkansas is reflected in its land mollusks, i.e., approximately 40% of Arkansas species are also widely distributed in the United States east of the Rocky Mountains, 12% are more widely distributed to the north, 11% are typical of the Gulf Coastal Plain, 14% form a Mid Western assemblage and 18% are endemic to the Ouachita-Ozark regions of Arkansas, Oklahoma and Missouri. The remaining 5% are species for which the geographic distribution is unclear. Diversity of Arkansas land mollusks is apparently due to the conjunction of these geographical zones within the state. Taxonomic problems exist for the genera Mesomphix and Paravitrea (family Zonitidae) and Succinea (family Succineidae) in Arkansa

An Evidence Based Methodology for Cultural Institutions Seeking to Identify and Profile their Local Populations

This is the author accepted manuscript. The final version is available from Taylor & Francis (Routledge) via the DOI in this record.Community is a term utilised in policy to describe a collective target audience for public services. Political requirements mean that delivering direct and indirect benefits to local people is regarded as essential to obtaining public sources of funding for cultural organisations. Regardless of any external pressure, cultural organisations strive to be conscious, receptive or inclusive of the views of the public. This paper summarises how a robust approach was developed to identify and profile groupings of residents within an area in relation to their local civic museum (UK). This method resulted in a nuanced understanding of a museum’s local population, identifying groupings upon which to base its future plans. Crucially, the methods outlined in this paper are transferable to cultural institutions in different settings worldwide. Our discussion contributes to the wider endeavour of evidencing impacts of museums on variously defined communities

A Test of the Particle Paradigm in N-Body Simulations

We present results of tests of the evolution of small ``fluid elements'' in cosmological N--body simulations, to examine the validity of their treatment as particles. We find that even very small elements typically collapse along one axis while expanding along another, often to twice or more their initial comoving diameter. This represents a possible problem for high--resolution uses of such simulations.Comment: Uses aasms4.sty; accepted for publication in ApJ Letters. Files available also at ftp://kusmos.phsx.ukans.edu/preprints/ates

Liquid droplet radiator program at the NASA Lewis Research Center

The NASA Lewis Research Center and the Air Force Rocket Propulsion Laboratory (AFRPL) are jointly engaged in a program for technical assessment of the Liquid Droplet Radiator (LDR) concept as an advanced high performance heat ejection component for future space missions. NASA Lewis has responsibility for the technology needed for the droplet generator, for working fluid qualification, and for investigating the physics of droplets in space; NASA Lewis is also conducting systems/mission analyses for potential LDR applications with candidate space power systems. For the droplet generator technology task, both micro-orifice fabrication techniques and droplet stream formation processes have been experimentally investigated. High quality micro-orifices (to 50 micron diameter) are routinely fabricated with automated equipment. Droplet formation studies have established operating boundaries for the generation of controlled and uniform droplet streams. A test rig is currently being installed for the experimental verification, under simulated space conditions, of droplet radiation heat transfer performance analyses and the determination of the effect radiative emissivity of multiple droplet streams. Initial testing has begun in the NASA Lewis Zero-Gravity Facility for investigating droplet stream behavior in microgravity conditions. This includes the effect of orifice wetting on jet dynamics and droplet formation. Results for both Brayton and Stirling power cycles have identified favorable mass and size comparisons of the LDR with conventional radiator concepts

Induced Shrinkage and Structural Reorganisation in Ammonia-Treated Wood of Corsican Pine

The ammonia-induced shrinkage of Corsican pine wood (Pinus nigra var. calabrica) was determined over a wide range of temperature, from the melting point (-78 C) to above the critical temperature (132 C) of liquid anhydrous ammonia. The swelling of wood was also measured but over a slightly more limited temperature range. The observed swelling and induced shrinkage of wood are explained in terms of two principal mechanisms: crimping and internal swelling of latewood and collapse of earlywood fibres. Confirmation of these mechanisms was provided by electron microscopy studies. Wood is most effectively plasticized between -5 and -33 C and this would seem to be the optimum temperature range for treating wood