55 research outputs found
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
Probing exotic phenomena at the interface of nuclear and particle physics with the electric dipole moments of diamagnetic atoms: A unique window to hadronic and semi-leptonic CP violation
The current status of electric dipole moments of diamagnetic atoms which
involves the synergy between atomic experiments and three different theoretical
areas -- particle, nuclear and atomic is reviewed. Various models of particle
physics that predict CP violation, which is necessary for the existence of such
electric dipole moments, are presented. These include the standard model of
particle physics and various extensions of it. Effective hadron level combined
charge conjugation (C) and parity (P) symmetry violating interactions are
derived taking into consideration different ways in which a nucleon interacts
with other nucleons as well as with electrons. Nuclear structure calculations
of the CP-odd nuclear Schiff moment are discussed using the shell model and
other theoretical approaches. Results of the calculations of atomic electric
dipole moments due to the interaction of the nuclear Schiff moment with the
electrons and the P and time-reversal (T) symmetry violating
tensor-pseudotensor electron-nucleus are elucidated using different
relativistic many-body theories. The principles of the measurement of the
electric dipole moments of diamagnetic atoms are outlined. Upper limits for the
nuclear Schiff moment and tensor-pseudotensor coupling constant are obtained
combining the results of atomic experiments and relativistic many-body
theories. The coefficients for the different sources of CP violation have been
estimated at the elementary particle level for all the diamagnetic atoms of
current experimental interest and their implications for physics beyond the
standard model is discussed. Possible improvements of the current results of
the measurements as well as quantum chromodynamics, nuclear and atomic
calculations are suggested.Comment: 46 pages, 19 tables and 16 figures. A review article accepted for
EPJ
Efeitos das misturas de alguns alimentos na produção de óvulos em Anastrepha obliqua (Diptera, Tephritidae)
Measurement of the Top Quark Mass in the Dilepton Channel
We report a measurement of the top quark mass using six candidate events for
the process pbarp->ttbar->l^+ nu l^- nubar b bbar + X, observed in the D0
experiment at the Fermilab ppbar collider. Using maximum likelihood fits to the
dynamics of the decays, we measure a mass for the top quark of m(top) = 168.4
+- 12.3 (stat) +- 3.6 (syst) GeV/c^2. We combine this result with our previous
measurement in the ttbar->l+jets channel to obtain m(top) = 172.1 +- 7.1
GeV/c^2 as the best value of the mass of the top quark measured by D0.Comment: 48 pages, 22 figures (encapsultaed postscript), Submitted for
publication in Physical Review
Dynamic cardiovascular risk assessment in the elderly:The role of repeated amino terminal pro-B-type natriuretic peptide testing
OBJECTIVES: Determine if serial measurement of N-terminal pro B-type natriuretic peptide (NT-proBNP) in community dwelling elderly would provide additional prognostic information to traditional risk factors. BACKGROUND: Accurate cardiovascular risk stratification is challenging in the elderly. METHODS: NT-proBNP was measured at baseline and 2-3 years later in 2,975 community-dwelling older adults free of heart failure in the longitudinal Cardiovascular Health Study. This investigation examined the risk of new-onset heart failure (HF) and death from cardiovascular (CV) causes associated with baseline NT-proBNP and changes in NT-proBNP levels, adjusting for potential confounders. RESULTS: NT-proBNP levels in the highest quintile (>267.7 pg/mL) were independently associated with greater risks of HF (hazard ratio [HR] =3.05 (95%CI [confidence interval] 2.46-3.78) and CV death (HR=3.02, 95%CI 2.36-3.86) compared to the lowest quintile (<47.5 pg/mL). The inflection point for elevated risk occurred at NT-proBNP=190 pg/mL. Among participants with initially low NT-proBNP (<190 pg/mL), those who developed a >25% increase on follow-up to >190 pg/mL (21%) were at greater adjusted risk of HF (HR=2.13, 95%CI=1.68-2.71) and CV death (HR=1.91, 95%CI=1.43-2.53) compared to those with sustained low levels. Among participants with initially high NT-proBNP, those who developed >25% increase (40%) were at higher risk of HF (HR=2.06 95%CI 1.56 −2.72) and cardiovascular death (HR=1.88, 95%CI 1.37-2.57), whereas those who developed >25% decrease to ≤190pg/mL (15%) were at lower risk of HF (HR=0.58, 95%CI 0.36-0.93) and CV death (HR=0.57, 95%CI 0.32 −1.01) compared to those with unchanged high values. CONCLUSION: NT-proBNP levels independently predict heart failure and cardiovascular death in older adults. NT-proBNP levels frequently change over time and these fluctuations reflect dynamic changes in cardiovascular risk
Predictive value of depressive symptoms and B-type natriuretic peptide for new-onset heart failure and mortality
Depression and natriuretic peptides predict heart failure (HF) progression, but the unique contributions of depression and biomarkers associated with HF outcomes are not known. The present study determined the additive predictive value of depression and aminoterminal pro-B-type natriuretic peptide (NT-proBNP) for new-onset HF in HF-free subjects and mortality in patients with HF. The participants in the Cardiovascular Health Study were assessed for depressive symptoms using the Center for Epidemiologic Studies Depression Scale and NT-proBNP using an electrochemiluminescence immunoassay. The validated cutoff values for depression (Center for Epidemiologic Studies Depression Scale ≥8) and NT-proBNP (≥190 pg/ml) were used. The risks of incident HF and mortality (cardiovascular disease-related and all-cause) were examined during a median follow-up of 11 years, adjusting for demographics, clinical factors, and health behaviors. In patients with HF (n = 208), depression was associated with an elevated risk of cardiovascular disease mortality (hazard ratios [HR] 2.07, 95% confidence interval [CI] 1.31 to 3.27) and all-cause mortality (HR 1.49, 95% CI 1.05 to 2.11), independent of the NT-proBNP level and covariates. The combined presence of depression and elevated NT-proBNP was associated with substantially elevated covariate-adjusted risks of cardiovascular disease mortality (HR 5.42, 95% CI 2.38 to 12.36) and all-cause mortality (HR 3.72, 95% CI 2.20 to 6.37). In the 4,114 HF-free subjects, new-onset HF was independently predicted by an elevated NT-proBNP level (HR 2.27, 95% CI 1.97 to 2.62) but not depression (HR 1.08, 95% CI 0.92 to 1.26) in covariate-adjusted analysis. In conclusion, depression and NT-proBNP displayed additive predictive value for mortality in patients with HF. These associations can be explained by complementary pathophysiologic mechanisms. The presence of both elevated depression and NT-proBNP levels might improve the identification of patients with HF with a high risk of mortality
Cardiac microinjury measured by Troponin T predicts collagen metabolism in adults aged ≥65 years with heart failure
BACKGROUND: Repeated myocardial micro-injuries lead to collagen deposition and fibrosis, thereby increasing the risk of clinical heart failure. Little is known about the longitudinal association between increases in myocardial injury and the biology of collagen synthesis and deposition. METHODS AND RESULTS: Repeated measures of highly sensitive cardiac troponin T (cTnT) were obtained in participants of the Cardiovascular Health Study (N-353; mean age=74±6 years, 52% women) at baseline and at three years follow-up. Biomarkers of collagen metabolism were obtained at follow-up and included carboxyterminal propeptide of procollagen type I (PIP), carboxyterminal telopeptide of type I collagen (CITP); and aminoterminal propeptide of procollagen III (PIIINP). Multivariable linear regression analyses were used to examine the association between baseline cTnT and changes in cTnT with collagen metabolism markers at follow-up, adjusting for demographics, heart failure status, and cardiovascular risk factors. Results indicated that cTnT increases over 3-years were significantly associated with higher levels of CITP (β=0.22, p<0.001) and PIIINP (β=0.12, p=0.035) at follow-up when adjusting for demographic, clinical and biochemical covariates including baseline cTnT. These associations were stronger in heart failure patients than in controls. CONCLUSIONS: Increases in myocardial micro-injury measured by changes in cTnT adversely affect markers of collagen metabolism. These findings are important to the biology of myocardial fibrosis and tissue repair. Serial evaluation of cTnT combined with collagen metabolism markers may further elucidate the pathophysiology of heart failure
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