4,741 research outputs found
Use of the Response Surface Method for the Quantification of a Sexual Behavior Model
A microsimulation model of sexual behavior is developed, which simulates individual life histories of individuals in a hypothetical community. Heterogeneity of the community is taken into account. The model has the form of a discrete event system in which changes in the characteristics of the individuals result from random events that occur at random times. The model is quantified against real world data by a response surface method
Letter from A. C. Van Raalte to Paulus Den Bleyker
A letter of Albertus C. Van Raalte to Paulus den Bleyker of Kalamazoo about business matters. V.R. gives advice on how to do business in America, based on his experiences of four years since he himself came to America.https://digitalcommons.hope.edu/vrp_1850s/1462/thumbnail.jp
Enhancement of quasiparticle recombination in Ta and Al superconductors by implantation of magnetic and nonmagnetic atoms
The quasiparticle recombination time in superconducting films, consisting of
the standard electron-phonon interaction and a yet to be identified low
temperature process, is studied for different densities of magnetic and
nonmagnetic atoms. For both Ta and Al, implanted with Mn, Ta and Al, we observe
an increase of the recombination rate. We conclude that the enhancement of
recombination is not due to the magnetic moment, but arises from an enhancement
of disorder.Comment: 4 pages, 4 figure
Microscopic energy flows in disordered Ising spin systems
An efficient microcanonical dynamics has been recently introduced for Ising
spin models embedded in a generic connected graph even in the presence of
disorder i.e. with the spin couplings chosen from a random distribution. Such a
dynamics allows a coherent definition of local temperatures also when open
boundaries are coupled to thermostats, imposing an energy flow. Within this
framework, here we introduce a consistent definition for local energy currents
and we study their dependence on the disorder. In the linear response regime,
when the global gradient between thermostats is small, we also define local
conductivities following a Fourier dicretized picture. Then, we work out a
linearized "mean-field approximation", where local conductivities are supposed
to depend on local couplings and temperatures only. We compare the approximated
currents with the exact results of the nonlinear system, showing the
reliability range of the mean-field approach, which proves very good at high
temperatures and not so efficient in the critical region. In the numerical
studies we focus on the disordered cylinder but our results could be extended
to an arbitrary, disordered spin model on a generic discrete structures.Comment: 12 pages, 6 figure
Identification of TUB as a novel candidate gene influencing body weight in humans
Previously, we identified a locus on 11p influencing obesity in families with type 2 diabetes. Based on mouse studies, we selected TUB as a functional candidate gene and performed association studies to determine whether this controls obesity. We analyzed the genotypes of 13 single nucleotide polymorphisms (SNPs) around TUB in 492 unrelated type 2 diabetic patients with known BMI values. One SNP (rs1528133) was found to have a significant effect on BMI (1.54 kg/m(2), P = 0.006). This association was confirmed in a population enriched for type 2 diabetes, using 750 individuals who were not selected for type 2 diabetes. Two SNPs in linkage disequilibrium with rs1528133 and mapping to the 3' end of TUB, rs2272382, and rs2272383 also affected BMI by 1.3 kg/m2 (P = 0.016 and P = 0.010, respectively). Combined analysis confirmed this association (P = 0.005 and P = 0.002, respectively). Moreover, comparing 349 obese subjects (BMI >30 kg/m(2)) from the combined cohort with 289 normal subjects (BMI <25 kg/m(2)) revealed that the protective alleles have a lower frequency in obese subjects (odds ratio 1.32 [95% CI 1.04-1.67], P = 0.022). Altogether, data from the tubby mouse as well as these data suggest that TUB could be an important factor in controlling the central regulation of body weight in humans
Identification of Nuclear Factor IV/Ku autoantigen in a human 2D-gel protein database Modification of the large subunit depends on cellular proliferation
AbstractNuclear Factor IV (NFIV)is a heterodimeric DNA-binding protein from HeLa cells, recognizing molecular ends and is identical to the autoantigenic target Ku. We have identified the two NFIV/Ku subunits, by comigration, in the 2D-gel database of transformed human amnion cell (AMA) proteins. We observed that the large subunit or NFIV/Ku consists of at least 3 charge variants that correspond to SSP IEFs 5705 (81.2 kDa, pI 5.74), 6707 (81.2 kDa, pI 5.67) and 6706 (81.9 kDa, pI 5.60) in the AMA catalogue. The relative amounts of the 2 major variants (IEFs 5705 and 6707) was dependent on the state of cell proliferation. Inhibition of DNA-synthesis by hydroxyurea also changed the relative levels of the variants, whereas aphidicolin or a thymidine block had no effect. These results suggest a possible role for NFIV/Ku in DNA replication
Unintended consequences: Why carbonation can dominate in microscale hydration of calcium silicates
The initial microscale mechanisms and materials interfacial process responsible for hydration of calcium silicates are poorly understood even in model systems. The lack of a measured microscale chemical signature has confounded understanding of growth mechanisms and kinetics for microreaction volumes. Here, we use Raman and optical spectroscopies to quantify hydration and environmental carbonation of tricalcium silicates across length and time scales. We show via spatially resolved chemical analysis that carbonate formation during the initial byproduct in microscale reaction volumes is significant, even for subambient CO2 levels. We propose that the competition between carbonation and hydration is enhanced strongly in microscale reaction volumes by increased surface-to-volume ratio relative to macroscale volumes, and by increased concentration of dissolved Ca2+ ions under poor hydration conditions that promote evaporation. This in situ analysis provides the first direct correlation between microscale interfacial hydration and carbonation environments and chemically defined reaction products in cementitious materials.United States. Department of Homeland Security. Science and Technology DirectorateMIT Concrete Sustainability HubPortland Cement AssociationReady Mixed Concrete (RMC) Research & Education Foundatio
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