Segregation in a fluidized binary granular mixture: Competition between buoyancy and geometric forces

Starting from the hydrodynamic equations of binary granular mixtures, we derive an evolution equation for the relative velocity of the intruders, which is shown to be coupled to the inertia of the smaller particles. The onset of Brazil-nut segregation is explained as a competition between the buoyancy and geometric forces: the Archimedean buoyancy force, a buoyancy force due to the difference between the energies of two granular species, and two geometric forces, one compressive and the other-one tensile in nature, due to the size-difference. We show that inelastic dissipation strongly affects the phase diagram of the Brazil nut phenomenon and our model is able to explain the experimental results of Breu et al. (PRL, 2003, vol. 90, p. 01402).Comment: 5 pages, 2 figure

Baseline Outlook for Missouri Representative Farms 2003-2007

This report presents a five-year outlook for Missouri representative farms under provisions of the Food Security and Rural Investment Act of 2002.This material is based on work supported by the Cooperative State Research Education and Extension Service, U.S. Department of Agriculture, under agreement no. 2002-34228-11826

Generation of an expandable intermediate mesoderm restricted progenitor cell line from human pluripotent stem cells.

The field of tissue engineering entered a new era with the development of human pluripotent stem cells (hPSCs), which are capable of unlimited expansion whilst retaining the potential to differentiate into all mature cell populations. However, these cells harbor significant risks, including tumor formation upon transplantation. One way to mitigate this risk is to develop expandable progenitor cell populations with restricted differentiation potential. Here, we used a cellular microarray technology to identify a defined and optimized culture condition that supports the derivation and propagation of a cell population with mesodermal properties. This cell population, referred to as intermediate mesodermal progenitor (IMP) cells, is capable of unlimited expansion, lacks tumor formation potential, and, upon appropriate stimulation, readily acquires properties of a sub-population of kidney cells. Interestingly, IMP cells fail to differentiate into other mesodermally-derived tissues, including blood and heart, suggesting that these cells are restricted to an intermediate mesodermal fate

Therapeutic modalities for central nervous system involvement by granulocytic sarcoma (chloroma) in children with acute nonlymphocytic leukemia.

Four cases of central nervous system involvement by granulocytic sarcoma (three intracranial and one paraspinal) in children with acute nonlymphocytic leukemia (FAB M1 or M2 subtype) are presented, and therapeutic modalities are discussed. All tumors were noted at initial presentation with diagnosis being made on clinical and radiological findings without biopsy. All patients had karyotypic abnormalities: three had translocation of chromosomes 8 and 21, and one had an unspecified hypodiploid clone. The three patients who developed intracranial tumors responded well to triple agent (cytosine arabinoside, hydrocortisone, and methotrexate) intrathecal chemotherapy and systemic chemotherapy, with or without local irradiation, as evidenced by rapid disappearance of the tumors. Two children are disease-free after 17 and 57 months. One patient with paraspinal tumor failed to achieve a systemic remission but had no evidence of granulocytic sarcoma at autopsy. Thus, the prognosis of CNS granulocytic sarcoma is not uniformly gloomy if treated aggressively by combined modalities. The value of surgical intervention in terms of primary management, however, is limited

Spectroscopic characterisation of the stellar content of ultra diffuse galaxies

Understanding the peculiar properties of Ultra Diffuse Galaxies (UDGs) via spectroscopic analysis is a challenging task requiring very deep observations and exquisite data reduction. In this work we perform one of the most complete characterisations of the stellar component of UDGs to date using deep optical spectroscopic data from OSIRIS at GTC. We measure radial and rotation velocities, star formation histories (SFH) and mean population parameters, such as ages and metallicities, for a sample of five UDG candidates in the Coma cluster. From the radial velocities, we confirm the Coma membership of these galaxies. We find that their rotation properties, if detected at all, are compatible with dwarf-like galaxies. The SFHs of the UDG are dominated by old (~ 7 Gyr), metal-poor ([M/H] ~ -1.1) and alpha-enhanced ([Mg/Fe] ~ 0.4) populations followed by a smooth or episodic decline which halted ~ 2 Gyr ago, possibly a sign of cluster-induced quenching. We find no obvious correlation between individual SFH shapes and any UDG morphological properties. The recovered stellar properties for UDGs are similar to those found for DDO44, a local UDG analogue resolved into stars. We conclude that the UDGs in our sample are extended dwarfs whose properties are likely the outcome of both internal processes, such as bursty SFHs and/or high-spin haloes, as well as environmental effects within the Coma cluster.Comment: Accepted for publication in MNRA