1,140 research outputs found

    Atomic Fermi gas in the trimerized Kagom\'e lattice at the filling 2/3

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    We study low temperature properties of an atomic spinless interacting Fermi gas in the trimerized Kagom\'e lattice for the case of two fermions per trimer. The system is described by a quantum spin 1/2 model on the triangular lattice with couplings depending on bonds directions. Using exact diagonalizations we show that the system exhibits non-standard properties of a {\it quantum spin-liquid crystal}, combining a planar antiferromagnetic order with an exceptionally large number of low energy excitations.Comment: 4 pages & 4 figures + 2 tables, better version of Fig.

    Comparison of Saturated Hydraulic Conductivity Measurement Methods for a Glacial-Till Soil

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    Hydraulic conductivity is the single most important hydraulic parameter for flow and transport-related phenomena in soil, but the results from different measuring methods vary under different field conditions. To evaluate the performance of four in situ saturated hydraulic conductivity (Ks) measuring methods, Ks measurements were made at four depths (15, 30, 60, and 90 cm) and five locations on a glacial-till soil of Nicollet (fine-loamy, mixed, mesic Aquic Hapludoll)-Clarion (fine-loamy, mixed, mesic Typic Hapludoll) association. The four in situ methods were: (i) Guelph permeameter, (ii) velocity permeameter, (iii) disk permeameter, and (iv) double-tube method. The Ks was also determined in the laboratory on undisturbed soil cores collected from all the five sites and four depths. The Guelph permeameter method gave the lowest Ks values, possibly because of small sample size, whereas the disk permeameter and double-tube methods gave maximum values for Ks with minimum variability, possibly because of large sample size. Maximum variability in Ks values for soil cores at shallow depths may have occurred because of the presence or absence of open-ended macropores. Estimates of Ks, however, are most comparable for the velocity permeameter and the laboratory method using a constant-head permeameter

    Colloid-oil-water-interface interactions in the presence of multiple salts: charge regulation and dynamics

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    We theoretically and experimentally investigate colloid-oil-water-interface interactions of charged, sterically stabilized, poly(methyl-methacrylate) colloidal particles dispersed in a low-polar oil (dielectric constant ϵ=510\epsilon=5-10) that is in contact with an adjacent water phase. In this model system, the colloidal particles cannot penetrate the oil-water interface due to repulsive van der Waals forces with the interface whereas the multiple salts that are dissolved in the oil are free to partition into the water phase. The sign and magnitude of the Donnan potential and/or the particle charge is affected by these salt concentrations such that the effective interaction potential can be highly tuned. Both the equilibrium effective colloid-interface interactions and the ion dynamics are explored within a Poisson-Nernst-Planck theory, and compared to experimental observations.Comment: 13+2 pages, 5+3 figures; V2: small clarifications in the tex

    Jaw and Long Bone Marrows Have a Different Osteoclastogenic Potential

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    Osteoclasts, the multinucleated bone-resorbing cells, arise through fusion of precursors from the myeloid lineage. However, not all osteoclasts are alike; osteoclasts at different bone sites appear to differ in numerous respects. We investigated whether bone marrow cells obtained from jaw and long bone differed in their osteoclastogenic potential. Bone marrow cells from murine mandible and tibiae were isolated and cultured for 4 and 6 days on plastic or 6 and 10 days on dentin. Osteoclastogenesis was assessed by counting the number of TRAP+ multinucleated cells. Bone marrow cell composition was analyzed by FACS. The expression of osteoclast- and osteoclastogenesis-related genes was studied by qPCR. TRAP activity and resorptive activity of osteoclasts were measured by absorbance and morphometric analyses, respectively. At day 4 more osteoclasts were formed in long bone cultures than in jaw cultures. At day 6 the difference in number was no longer observed. The jaw cultures, however, contained more large osteoclasts on plastic and on dentin. Long bone marrow contained more osteoclast precursors, in particular the myeloid blasts, and qPCR revealed that the RANKL:OPG ratio was higher in long bone cultures. TRAP expression was higher for the long bone cultures on dentin. Although jaw osteoclasts were larger than long bone osteoclasts, no differences were found between their resorptive activities. In conclusion, bone marrow cells from different skeletal locations (jaw and long bone) have different dynamics of osteoclastogenesis. We propose that this is primarily due to differences in the cellular composition of the bone site-specific marrow
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