34 research outputs found

    Doping-dependent study of the periodic Anderson model in three dimensions

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    We study a simple model for ff-electron systems, the three-dimensional periodic Anderson model, in which localized ff states hybridize with neighboring dd states. The ff states have a strong on-site repulsion which suppresses the double occupancy and can lead to the formation of a Mott-Hubbard insulator. When the hybridization between the ff and dd states increases, the effects of these strong electron correlations gradually diminish, giving rise to interesting phenomena on the way. We use the exact quantum Monte-Carlo, approximate diagrammatic fluctuation-exchange approximation, and mean-field Hartree-Fock methods to calculate the local moment, entropy, antiferromagnetic structure factor, singlet-correlator, and internal energy as a function of the fdf-d hybridization for various dopings. Finally, we discuss the relevance of this work to the volume-collapse phenomenon experimentally observed in f-electron systems.Comment: 12 pages, 8 figure

    Identification of women at risk for developing postmenopausal osteoporosis with vertebral fractures: role of history and single photon absorptiometry

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    Putative risk factors for the development of postmenopausal osteoporosis (PMO) with vertebral fractures were examined in a retrospective study of 663 postmenopausal white females aged 45-75 years (266 women with non-traumatic vertebral compression fractures (VF+), 134 non-fractured women from a general medicine clinic (controls) and 263 non-fractured women who were evaluated when they presented specifically for osteoporosis screening (VF-)). The VF+ women differed from control women in several respects. The VF+ group reported a higher prevalence of a positive family history of osteoporosis, and a higher prevalence of a history of medical or surgical conditions known to be independently associated with metabolic bone disease, had fewer children, were smaller (weight, height) and were slightly older. The two groups, VF+ and controls, did not differ with respect to cigarette smoking, alcohol consumption, exercise habits, menstrual or menopausal history, dietary intake of milk and cheese or in amount taking calcium supplements during pregnancy.The VF+ group also differed in certain respects from the VF- group. The VF+ group were smaller (weight, height) and were older. The VF+ group had lower cortical bone mass (measured by single photon absorptiometry of the non-dominant forearm) than either the control or VF- groups. The latter two groups did not differ from each other with respect to this measurement.These markers demonstrated limited sensitivity and specificity as estimated from a confirmatory data set, particularly for the historical and anthropometric variables. We conclude that an assessment of the risk of developing PMO with vertebral fractures cannot be based on the putative risk factors as measured in our study, but must be based on measurement of bone mass.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27770/1/0000164.pd

    Socioecological stressor areas and black-white blood pressure: Detroit

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    1. 1. Blood pressure does appear to vary with `socioecological niches' or combinations of sex, race and residence, which reflect social class position as well as degree of social stressor conditions. Black High Stress males had higher adjusted levels than Black Low Stress males, while White High Stress females had higher adjusted pressures than White Low Stress females. Black High Stress females had significantly higher observed levels than Black Low Stress females.2. 2. Black High Stress males had a significantly higher per cent of Borderline and Hypertensive blood pressure than other male race-area groups; White Low Stress females had the lowest of all eight sex-race-stress area groups.3. 3. For Black males, the younger, overweight High Stress residents had significantly higher Borderline and Hypertensive levels than did a similar Black Low Stress subgroup. Further, for both groups, being raised in Detroit and not migrating from elsewhere was related to higher readings. Tests for age-stress area interaction, however, were not significant.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33823/1/0000080.pd

    Genetic Sharing with Cardiovascular Disease Risk Factors and Diabetes Reveals Novel Bone Mineral Density Loci.

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    Bone Mineral Density (BMD) is a highly heritable trait, but genome-wide association studies have identified few genetic risk factors. Epidemiological studies suggest associations between BMD and several traits and diseases, but the nature of the suggestive comorbidity is still unknown. We used a novel genetic pleiotropy-informed conditional False Discovery Rate (FDR) method to identify single nucleotide polymorphisms (SNPs) associated with BMD by leveraging cardiovascular disease (CVD) associated disorders and metabolic traits. By conditioning on SNPs associated with the CVD-related phenotypes, type 1 diabetes, type 2 diabetes, systolic blood pressure, diastolic blood pressure, high density lipoprotein, low density lipoprotein, triglycerides and waist hip ratio, we identified 65 novel independent BMD loci (26 with femoral neck BMD and 47 with lumbar spine BMD) at conditional FDR < 0.01. Many of the loci were confirmed in genetic expression studies. Genes validated at the mRNA levels were characteristic for the osteoblast/osteocyte lineage, Wnt signaling pathway and bone metabolism. The results provide new insight into genetic mechanisms of variability in BMD, and a better understanding of the genetic underpinnings of clinical comorbidity

    Novel genetic loci associated with hippocampal volume

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    The hippocampal formation is a brain structure integrally involved in episodic memory, spatial navigation, cognition and stress responsiveness. Structural abnormalities in hippocampal volume and shape are found in several common neuropsychiatric disorders. To identify the genetic underpinnings of hippocampal structure here we perform a genome-wide association study (GWAS) of 33,536 individuals and discover six independent loci significantly associated with hippocampal volume, four of them novel. Of the novel loci, three lie within genes (ASTN2, DPP4 and MAST4) and one is found 200 kb upstream of SHH. A hippocampal subfield analysis shows that a locus within the MSRB3 gene shows evidence of a localized effect along the dentate gyrus, subiculum, CA1 and fissure. Further, we show that genetic variants associated with decreased hippocampal volume are also associated with increased risk for Alzheimer's disease (rg =-0.155). Our findings suggest novel biological pathways through which human genetic variation influences hippocampal volume and risk for neuropsychiatric illness

    Blood pressure dependent and independent effects of antihypertensive treatment on clinical events in the VALUE Trial

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    (VALUE) trial was designed to test whether, for the same achieved blood pressures, regimens based on valsartan or amlodipine would have differing effects on cardiovascular endpoints in high risk hypertension. But inequalities in blood pressure, favouring amlodipine, throughout the multiyear trial precluded comparison of outcomes. A technique of serial median matching, applied at 6 months when treatment adjustments intended to achieve control of blood pressure were complete, created 5006 valsartan-amlodipine patient pairs matched exactly for systolic blood pressure, age, sex, and the presence or absence of previous coronary disease, stroke, or diabetes. Subsequent combined cardiac events, myocardial infarction, stroke, and mortality were almost identical in the two cohorts, but admission to hospital for heart failure was significantly lower with valsartan. Reaching blood pressure control (systolic &lt;140 mm Hg) by 6 months, independent of drug type, was associated with significant benefits for subsequent major outcomes; the blood pressure response after just 1 month of treatment predicted events and survival

    Usefulness of heart rate to predict cardiac events in treated patients with high-risk systemic hypertension.

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    A high heart rate (HR) predicts future cardiovascular events. We explored the predictive value of HR in patients with high-risk hypertension and examined whether blood pressure reduction modifies this association. The participants were 15,193 patients with hypertension enrolled in the Valsartan Antihypertensive Long-term Use Evaluation (VALUE) trial and followed up for 5 years. The HR was assessed from electrocardiographic recordings obtained annually throughout the study period. The primary end point was the interval to cardiac events. After adjustment for confounders, the hazard ratio of the composite cardiac primary end point for a 10-beats/min of the baseline HR increment was 1.16 (95% confidence interval 1.12 to 1.20). Compared to the lowest HR quintile, the adjusted hazard ratio in the highest quintile was 1.73 (95% confidence interval 1.46 to 2.04). Compared to the pooled lower quintiles of baseline HR, the annual incidence of primary end point in the top baseline quintile was greater in each of the 5 study years (all p &lt;0.05). The adjusted hazard ratio for the primary end point in the highest in-trial HR heart rate quintile versus the lowest quintile was 1.53 (95% confidence interval 1.26 to 1.85). The incidence of primary end points in the highest in-trial HR group compared to the pooled 4 lower quintiles was 53% greater in patients with well-controlled blood pressure (p &lt;0.001) and 34% greater in those with uncontrolled blood pressure (p = 0.002). In conclusion, an increased HR is a long-term predictor of cardiovascular events in patients with high-risk hypertension. This effect was not modified by good blood pressure control. It is not yet known whether a therapeutic reduction of HR would improve cardiovascular prognosis

    Effects of valsartan compared to amlodipine on preventing type 2 diabetes in high-risk hypertensive patients: the VALUE trial

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    CONTEXT: Type 2 diabetes is emerging as a major health problem, which tends to cluster with hypertension in individuals at high risk of cardiovascular disease. OBJECTIVE: To test for the first time the hypothesis that treatment of hypertensive patients at high cardiovascular risk with the angiotensin-receptor blocker (ARB) valsartan prevents new-onset type 2 diabetes compared with the metabolically neutral calcium-channel antagonist (CCA) amlodipine. DESIGN: Pre-specified analysis in the VALUE trial. Follow-up averaged 4.2 years. The risk of developing new diabetes was calculated as an odds ratio (OR) with 95% confidence intervals (CI) for different definitions of diabetes. PATIENTS: A sample of 9995 high-risk, non-diabetic hypertensive patients. INTERVENTIONS: Valsartan or amlodipine with or without add-on medication [hydrochlorothiazide (HCTZ) and other add-ons, excluding other ARBs, angiotensin-converting enzyme (ACE) inhibitors, CCAs]. MAIN OUTCOME MEASURE: New diabetes defined as an adverse event, new blood-glucose-lowering drugs and/or fasting glucose > 7.0 mmol/l. RESULTS: New diabetes was reported in 580 (11.5%) patients on valsartan and in 718 (14.5%) patients on amlodipine (OR 0.77, 95% CI 0.69-0.87, P < 0.0001). Using stricter criteria (without adverse event reports) new diabetes was detected in 495 (9.8%) patients on valsartan and in 586 (11.8%) on amlodipine (OR 0.82, 95% CI 0.72-0.93, P = 0.0015). CONCLUSION: Compared with amlodipine, valsartan reduces the risk of developing diabetes mellitus in high-risk hypertensive patients

    Two separate, large cohorts reveal potential modifiers of age-associated variation in visual reaction time performance

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    To identify potential factors influencing age-related cognitive decline and disease, we created MindCrowd. MindCrowd is a cross-sectional web-based assessment of simple visual (sv) reaction time (RT) and paired-associate learning (PAL). svRT and PAL results were combined with 22 survey questions. Analysis of svRT revealed education and stroke as potential modifiers of changes in processing speed and memory from younger to older ages (ntotal = 75,666, nwomen = 47,700, nmen = 27,966; ages 18–85 years old, mean (M)Age = 46.54, standard deviation (SD)Age = 18.40). To complement this work, we evaluated complex visual recognition reaction time (cvrRT) in the UK Biobank (ntotal = 158,249 nwomen = 89,333 nmen = 68,916; ages 40–70 years old, MAge = 55.81, SDAge = 7.72). Similarities between the UK Biobank and MindCrowd were assessed using a subset of MindCrowd (UKBb MindCrowd) selected to mirror the UK Biobank demographics (ntotal = 39,795, nwomen = 29,640, nmen = 10,155; ages 40–70 years old, MAge = 56.59, SDAge = 8.16). An identical linear model (LM) was used to assess both cohorts. Analyses revealed similarities between MindCrowd and the UK Biobank across most results. Divergent findings from the UK Biobank included (1) a first-degree family history of Alzheimer’s disease (FHAD) was associated with longer cvrRT. (2) Men with the least education were associated with longer cvrRTs comparable to women across all educational attainment levels. Divergent findings from UKBb MindCrowd included more education being associated with shorter svRTs and a history of smoking with longer svRTs from younger to older ages. © 2021, The Author(s).Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
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