A Gaussian distribution for refined DT invariants and 3D partitions

We show that the refined Donaldson-Thomas invariants of C3, suitably normalized, have a Gaussian distribution as limit law. Combinatorially these numbers are given by weighted counts of 3D partitions. Our technique is to use the Hardy-Littlewood circle method to analyze the bivariate asymptotics of a q-deformation of MacMahon's function. The proof is based on that of E.M. Wright who explored the single variable case.Comment: 11 pages and 3 figure

Laboratory and field evaluation of polyurethane foam for lost circulation control

A two-part polyurethane foam has been tested in the laboratory and in the field to assess its utility in controlling lost circulation encountered when drilling geothermal wells. A field test was conducted in The Geysers in January, 1988, to evaluate the chemical formulation and downhole tool used to deploy the chemicals. Although the tool apparently functioned properly in the field test, the chemicals failed to expand sufficiently downhole, instead forming a dense polymer that may be ineffective in sealing loss zones. Subsequent laboratory tests conducted under simulated downhole conditions indicate that the foam chemical undergo sever mixing with water in the wellbore, which disturbs the kinetics of the chemical reaction more than was previously contemplated. The results indicate that without significant changes in the foam chemical formulation or delivery technique, the foam system will be ineffective in lost circulation control except under very favorable conditions. 4 refs., 6 figs., 2 tabs

Quasiparticle excitation in and around the vortex core of underdoped YBa_2Cu_4O_8 studied by site-selective NMR

We report a site-selective ^{17}O spin-lattice relaxation rate T_1^{-1} in the vortex state of underdoped YBa_2Cu_4O_8. We found that T_1^{-1} at the planar sites exhibits an unusual nonmonotonic NMR frequency dependence. In the region well outside the vortex core, T_1^{-1} cannot be simply explained by the density of states of the Doppler-shifted quasiparticles in the d-wave superconductor. Based on T_1^{-1} in the vortex core region, we establish strong evidence that the local density of states within the vortex core is strongly reduced.Comment: 5 pages, 3 figure

Generation of vortices and observation of Quantum Turbulence in an oscillating Bose-Einstein Condensate

We report on the experimental observation of vortex formation and production of tangled vortex distribution in an atomic BEC of Rb-87 atoms submitted to an external oscillatory perturbation. The oscillatory perturbations start by exciting quadrupolar and scissors modes of the condensate. Then regular vortices are observed finally evolving to a vortex tangle configuration. The vortex tangle is a signature of the presence of a turbulent regime in the cloud. We also show that this turbulent cloud has suppression of the aspect ratio inversion typically observed in quantum degenerate bosonic gases during free expansion.Comment: to appear in JLTP - QFS 200

Herpes Simplex Virus Type 1 (HSV-1) Uracil-DNA Glycosylase: Functional Expression in Escherichia coli, Biochemical Characterization, and Selective Inhibition by 6-(p-n-Octylanilino)Uracil

AbstractThe Herpes simplex virus type 1 (HSV-1) uracil-DNA glycosylase (UDG) is encoded by the UL2 gene. The translation from the first putative start codon of UL2 predicts a polypeptide of 334 residues, while the translation from the second start codon predicts a polypeptide of 244 residues. We have cloned and expressed the two forms of UDG, by means of the prokaryotic expression vector pMAL-c2, and both of them were enzymatically active. Furthermore, the enzymatic properties of the recombinant UDGs and of the enzyme purified from HSV-1-infected cells were similar. The two UDG polypeptides have molecular weights of 27 and 37 kDa, respectively. The 37-kDa form of recombinant UDG is consistent with the reported molecular mass of 37 kDa for the enzyme purified from HSV-1-infected cells. Both recombinant UDGs were as sensitive as UDG purified from HSV-1-infected cells to 6-(p-n-octylanilino)uracil, the most potent of a series of uracil analogs that inhibit the viral enzyme

Maturational changes in dentin mineral properties

In this study the changes in properties of the maturing mantle and circumpulpal dentin were quantitatively analyzed. Sections from six fetal bovine undecalcified incisors were used. Regions of mantle and circumpulpal dentin of sequential maturation stages were identified on spectroscopic images acquired by Fourier Transform Infrared Imaging. Spectroscopic parameters corresponding to mineral properties at these stages were analyzed and reported as a function of distance from the cervix of the incisor, the latter representing tissue age. Mineral parameters were correlated with distance from the cervix. Values of these parameters in mantle and circumpulpal dentin were compared. A multi-phasic pattern of changes was found for all the parameters examined, with most of the alterations occurring in the initial maturation period. The patterns of temporal variation in mantle and circumpulpal dentin mineral properties show distinct developmental stages and were not identical for the two dentin compartments. The study showed that mineral maturation in dentin is not a linear process and that mantle dentin is developmentally distinct from circumpulpal dentin, presenting at certain stages different physicochemical events during the maturation of the tissue

Soil-landscape and climatic relationships in the middle Miocene of the Madrid Basin

The Miocene alluvial-lacustrine sequences of the Madrid Basin, Spain, formed in highly varied landscapes. The presence of various types of palaeosols allows assessment of the effects of local and external factors onsedimentation, pedogenesis and geomorphological development. In the northern, more arid, tectonicallyactive arca, soils were weakly developed in aggrading alluvial fans, dominated by mass flows. reflecting high sedimentation rates. In more distal parts of the fans and in playa lakes calcretes and dolocretes developed: the former were associated with Mg-poor fan sediments whitc: the latter formed on Mg-rich lake clays exposed during minar lake lowstands. The nonh-east part of the basin had a less arid climate. Alluvial fans in this area were dominated by stream Aood deposits, sourced by carbonate terrains. Floodplain and freshwater lakc deposits formed in distal areas. The high local supply of calcium carbonate may have contributed to the preferential developmenl on calcretes on the fans. Both the fan and floodplain palaeosols exhibit pedofacies relationships and more mature soils developed in settings more distant from the sediment sources. Palaeosols also developed on pond and lake margin carbonates, and led to the formation of palustrine limestones. The spatial distributions and stratigraphies of palaeosols in the Madrid Basin alluvial fans suggest that soil formation was controlled by local factors. These palaeosols differ from those seen in Quatemary fans. Which are characterized by climatically induced periods of stability and instability