Simulations of error in quantum adiabatic computations of random 2-SAT instances

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2006.Includes bibliographical references (p. 45).This thesis presents a series of simulations of quantum computations using the adiabatic algorithm. The goal is to explore the effect of error, using a perturbative approach that models 1-local errors to the Hamiltonian and estimates transition probabilities out of the ground state. The data show that a perturbation in the z-direction, parallel to the alignment of the computational basis, causes a greater error than one in the x-direction, and show with good confidence (X2/[nu] = 1.7) that the variation is as sin [theta] where [theta] is the angle of the error term. An attempt to explore the change in error with the number of qubits was inconclusive--there was no measurable variation.by Jay S. Gill.S.B

Severity of parkinsonism associated with environmental manganese exposure

BACKGROUND: Exposure to occupational manganese (Mn) is associated with neurotoxic brain injury, manifesting primarily as parkinsonism. The association between environmental Mn exposure and parkinsonism is unclear. To characterize the association between environmental Mn exposure and parkinsonism, we performed population-based sampling of residents older than 40 in Meyerton, South Africa (N = 621) in residential settlements adjacent to a large Mn smelter and in a comparable non-exposed settlement in Ethembalethu, South Africa (N = 95) in 2016-2020. METHODS: A movement disorders specialist examined all participants using the Unified Parkinson Disease Rating Scale motor subsection part 3 (UPDRS3). Participants also completed an accelerometry-based kinematic test and a grooved pegboard test. We compared performance on the UPDRS3, grooved pegboard, and the accelerometry-based kinematic test between the settlements using linear regression, adjusting for covariates. We also measured airborne PM RESULTS: Mean PM CONCLUSIONS: Environmental airborne Mn exposures at levels substantially lower than current occupational exposure thresholds in the United States may be associated with clinical parkinsonism

Chromium isotope fractionation during subduction-related metamorphism, black shale weathering, and hydrothermal alteration

© The Author(s), 2016. This is the author's version of the work and is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Chemical Geology 423 (2016): 19-33, doi:10.1016/j.chemgeo.2016.01.003.Chromium (Cr) isotopes are an emerging proxy for redox processes at Earth’s surface. However, many geological reservoirs and isotope fractionation processes are still not well understood. The purpose of this contribution is to move forward our understanding of (1) Earth’s high temperature Cr isotope inventory and (2) Cr isotope fractionations during subduction-related metamorphism, black shale weathering and hydrothermal alteration. The examined basalts and their metamorphosed equivalents yielded δ53Cr values falling within a narrow range of -0.12±0.13‰ (2SD, n=30), consistent with the previously reported range for the bulk silicate Earth (BSE). Compilations of currently available data for fresh silicate rocks (43 samples), metamorphosed silicate rocks (50 samples), and mantle chromites (39 samples) give δ53Cr values of -0.13±0.13‰, -0.11±0.13‰, and -0.07±0.13‰, respectively. Although the number of high-temperature samples analyzed has tripled, the originally proposed BSE range appears robust. This suggests very limited Cr isotope fractionation under high temperature conditions. Additionally, in a highly altered metacarbonate transect that is representative of fluid-rich regional metamorphism, we did not find resolvable variations in δ53Cr, despite significant loss of Cr. This work suggests that primary Cr isotope signatures may be preserved even in instances of intense metamorphic alteration at relatively high fluid-rock ratios. Oxidative weathering of black shale at low pH creates isotopically heavy mobile Cr(VI). However, a significant proportion of the Cr(VI) is apparently immobilized near the weathering surface, leading to local enrichment of isotopically heavy Cr (δ53Cr values up to ~0.5‰). The observed large Cr isotope variation in the black shale weathering profile provides indirect evidence for active manganese oxide formation, which is primarily controlled by microbial activity. Lastly, we found widely variable δ53Cr (-0.2‰ to 0.6‰) values in highly serpentinized peridotites from ocean drilling program drill cores and outcropping ophiolite sequences. The isotopically heavy serpentinites are most easily explained through a multi-stage alteration processes: Cr loss from the host rock under oxidizing conditions, followed by Cr enrichment under sulfate reducing conditions. In contrast, Cr isotope variability is limited in mildly altered mafic oceanic crust.Funding for this research was provided by Agouron Institute to XLW, National Science Foundation (NSF) EAR-0105927 and EAR-1250269 to JJA, and NSF EAR-1324566 to ES. NJP and CTR acknowledge funding from the Alternative Earths NAI.2017-01-1

HTLV-III Serology in Hemophilia: Relationship with Immunologic Abnormalities

We investigated the relationship of the presence of antibodies to HTLV-III and immunologic abnormalities in patients with hemophilia. Serum antibodies to HTLV-III were analyzed by ELISA assay, immunoprecipitation of labeled cell extracts, and immunoprecipitation of purified HTLV-III p24. Thirty-four (61%) of the total group (n = 56) had antibody to HTLV-III; 34 (76%) of 45 patients given commercial factor VIII preparations were seropositive, compared with none of 11 patients treated exclusively with cryoprecipitate obtained from volunteer blood donors. Of patients who were seropositive for HTLV-III antibody, 94% had abnormal T4/T8 ratios, and 33% of those whose serum was antibody negative had abnormal T4/T8 ratios; five patients, each antibody positive, have lymphadenopathy syndrome. Sequential studies in a subset of patients indicate that there is a changing pattern of antibody production to HTLV-III antigens after seroconversion

HTLV-III Serology in Hemophilia: Relationship with Immunologic Abnormalities

We investigated the relationship of the presence of antibodies to HTLV-III and immunologic abnormalities in patients with hemophilia. Serum antibodies to HTLV-III were analyzed by ELISA assay, immunoprecipitation of labeled cell extracts, and immunoprecipitation of purified HTLV-III p24. Thirty-four (61%) of the total group (n = 56) had antibody to HTLV-III; 34 (76%) of 45 patients given commercial factor VIII preparations were seropositive, compared with none of 11 patients treated exclusively with cryoprecipitate obtained from volunteer blood donors. Of patients who were seropositive for HTLV-III antibody, 94% had abnormal T4/T8 ratios, and 33% of those whose serum was antibody negative had abnormal T4/T8 ratios; five patients, each antibody positive, have lymphadenopathy syndrome. Sequential studies in a subset of patients indicate that there is a changing pattern of antibody production to HTLV-III antigens after seroconversion

New Limits on an Intermediate Mass Black Hole in Omega Centauri: II. Dynamical Models

We present a detailed dynamical analysis of the projected density and kinematical data available for the globular cluster Omega Cen. We solve the spherical anisotropic Jeans equation to predict the projected profiles of the RMS velocity in each of the three orthogonal coordinate directions (line of sight, proper motion radial, and proper motion tangential). We fit the models to new HST star count and proper motion data near the cluster center presented in Paper I, combined with existing ground-based measurements. We also derive and model the Gauss-Hermite moments of the observed proper motion distributions. The projected density profile is consistent with being flat near the center, with an upper limit gamma=0.07 on the central logarithmic slope. The RMS proper motion profile is also consistent with being flat near the center, and there are no unusually fast-moving stars. The models provide a good fit and yield a 1-sigma upper limit MBH < 1.2E4 solar masses on the mass of a possible intermediate-mass black hole (IMBH). The inferred upper limit corresponds to MBH/Mtot < 0.43%. We combine this with results for other clusters and discuss the implications for globular cluster IMBH demographics. Tighter limits will be needed to rule out or establish whether globular clusters follow the same black hole demographics correlations as galaxies. The arguments put forward by Noyola et al. (2008) to suspect an IMBH in Omega Cen are not confirmed by our study; the IMBH mass they suggested is firmly ruled out.Comment: 28 pages, 11 figures, ApJ in press. v2 includes additions in response to referee comment