Sulphur and Carbon Isotopes as Tracers of Past Sub-seafloor Microbial Activity

Microbial life below the seafloor has changed over geological time, but these changes are often not obvious, as they are not recorded in the sediment. Sulphur (S) isotope values in pyrite extracted from a Plio- to Holocene sequence of the Peru Margin (Ocean Drilling Program, ODP, Site 1229) show a down-core pattern that correlates with the pattern of carbon (C) isotopes in diagenetic dolomite. Early formation of the pyrite is indicated by the mineralogical composition of iron, showing a high degree of pyritization throughout the sedimentary sequence. Hence, the S-record could not have been substantially overprinted by later pyrite formation. The S- and C-isotope profiles show, thus, evidence for two episodes of enhanced microbial methane production with a very shallow sulphate-methane transition zone. The events of high activity are correlated with zones of elevated organic C content in the stratigraphic sequence. Our results demonstrate how isotopic signatures preserved in diagenetic mineral phases provide information on changes of past biogeochemical activity in a dynamic sub-seafloor biosphere

Healthcare Reform for Imagers Finding a Way Forward Now

The changing healthcare environment presents many challenges to cardiovascular imagers. This perspective paper uses current trends to propose strategies that cardiovascular imagers can follow to lead in managing change and developing the imaging laboratory of the future. In the area of quality, imagers are encouraged to follow guidelines and standards, implement structured reporting and laboratory databases, adopt ongoing quality improvement programs, and use benchmarks to confirm imaging quality. In the area of access, imagers are encouraged to enhance availability of testing, focus on patient and referring physician value and satisfaction, collaboratively implement new technologies and uses of imaging, integrate health information technology in the laboratory, and work toward the appropriate inclusion of imaging in new healthcare delivery models. In the area of cost, imagers are encouraged to minimize laboratory operating expenses without compromising quality, and to take an active role in care redesign initiatives to ensure that imaging is utilized appropriately and at proper time intervals. Imagers are also encouraged to learn leadership and management skills, undertake strategic planning exercises, and build strong, collaborative teams. Although it is difficult to predict the future of cardiovascular imaging delivery, a reasonable sense of the likely direction of many changes and careful attention to the fundamentals of good health care (quality, access, and cost) can help imagers to thrive now and in the future

A Mitochondrial Health Index Sensitive to Mood and Caregiving Stress.

BACKGROUND:Chronic life stress, such as the stress of caregiving, can promote pathophysiology, but the underlying cellular mechanisms are not well understood. Chronic stress may induce recalibrations in mitochondria leading to changes either in mitochondrial content per cell, or in mitochondrial functional capacity (i.e., quality). METHODS:Here we present a functional index of mitochondrial health (MHI) for human leukocytes that can distinguish between these two possibilities. The MHI integrates nuclear and mitochondrial DNA-encoded respiratory chain enzymatic activities and mitochondrial DNA copy number. We then use the MHI to test the hypothesis that daily emotional states and caregiving stress influence mitochondrial function by comparing healthy mothers of a child with an autism spectrum disorder (high-stress caregivers, n = 46) with mothers of a neurotypical child (control group, n = 45). RESULTS:The MHI outperformed individual mitochondrial function measures. Elevated positive mood at night was associated with higher MHI, and nightly positive mood was also a mediator of the association between caregiving and MHI. Moreover, MHI was correlated to positive mood on the days preceding, but not following the blood draw, suggesting for the first time in humans that mitochondria may respond to proximate emotional states within days. Correspondingly, the caregiver group, which had higher perceived stress and lower positive and greater negative daily affect, exhibited lower MHI. This effect was not explained by a mismatch between nuclear and mitochondrial genomes. CONCLUSIONS:Daily mood and chronic caregiving stress are associated with mitochondrial functional capacity. Mitochondrial health may represent a nexus between psychological stress and health

The C(3P) + NH3 reaction in interstellar chemistry: II. Low temperature rate constants and modeling of NH, NH2 and NH3 abundances in dense interstellar clouds

A continuous supersonic flow reactor has been used to measure rate constants for the C + NH3 reaction over the temperature range 50 to 296 K. C atoms were created by the pulsed laser photolysis of CBr4. The kinetics of the title reaction were followed directly by vacuum ultra-violet laser induced fluorescence (VUV LIF) of C loss and through H formation. The experiments show unambiguously that the reaction is rapid at 296 K, becoming faster at lower temperatures, reaching a value of 1.8 10-10 cm3 molecule-1 s-1 at 50 K. As this reaction is not currently included in astrochemical networks, its influence on interstellar nitrogen hydride abundances is tested through a dense cloud model including gas-grain interactions. In particular, the effect of the ortho-to-para ratio of H2 which plays a crucial role in interstellar NH3 synthesis is examined

806-1 Left Ventricular Ejection Fraction After Myocardial Infarction: Importance of Both Infarct Site and Size

Left ventricular ejection fraction (LVEF) is an important prognostic variable after myocardial infarction (MI). While the extent of MI is known to affect the subsequent global LVEF, it is not clear whether anatomical site per se affects LVEF. Therefore, 48 consecutive patients (pts) who did not receive lytic therapy or undergo early revascularization were studied byechocardiography one week after Q wave MI. Using a previously validated endocardial mapping technique, the size of abnormal wall motion (AWM) in relation to the total endocardial surface area and the site of AWM were quantitated, LVEF was measured by Simpson's method using 2 apical views.ResultsNineteen pts had anterior MI (ANT) and 29 had inferior MI (INF). The mean LVEF was similar in both groups (ANT 46.9±14.7% vs INF 51.7±9.4%, pNS). The mean %AWM was greater in ANT MI (29.7±14.5) than in INF MI (21.3±13.8) (p=0.05). After accounting for differences in infarct size by multivariate regression analysis, both infarct size (p=0.0001) and infarct site (p=0.007) were significant independent determinants of LVEF. This effect was most pronounced in larger ANT Mis (%AWM>25%) where the LVEF was significantly lower than in smaller Mis. In INF MI, despite a similar range of sizes. increasing %AWM had minimal effect on LVEF.ConclusionIn addition to infarct size, the site of AWM is an important determinant of global LVEF. This observation may reflect site-dependent differences in the biomechanical responses to regional ventricular dysfunction

Modelling lexical phrases acquisition in L2

The study focuses on the following points. It compares the views psycholinguists and computational linguists have concerning the processes of lexical access and lexical choice. Then it shows the similarities holding between the structure of the lexicon in L1 and in L2. It tries to offer a pedagogically realistic approach in vocabulary teaching based on these results

Impredicativity and turn of the century foundations of mathematics : presupposition in Poincare and Russell

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Linguistics and Philosophy, 1993.Includes bibliographical references (leaves 145-158).by Joseph Romeo William Michael PicardPh.D

Flow tube studies of the C(3P) reactions with ethylene and propylene

International audienceProduct detection studies of C(3P) atom reactions with ethylene, C2H4(X1Ag) and propylene, C3H6(X1A′) are carried out in a flow tube reactor at 332 K and 4 Torr (553.3 Pa) under multiple collision conditions. Ground state carbon atoms are generated by 193 nm laser photolysis of carbon suboxide, C3O2 in a buffer of helium. Thermalized reaction products are detected using tunable VUV photoionization and time of flight mass spectrometry. For C(3P) + ethylene, propargyl (C3H3) is detected as the only molecular product in agreement with previous studies on this reaction. The temporal profiles of the detected ions are used to discriminate C(3P) reaction products from side reaction products. For C(3P) + propylene, two reaction channels are identified through the detection of methyl (CH3) and propargyl (C3H3) radicals for the first channel and C4H5 for the second one. Franck–Condon Factor simulations are employed to infer the C4H5-isomer distribution. The measured 1:4 ratio for the i-C4H5 isomer relative to the methylpropargyl isomers is similar to the C4H5 isomer distribution observed in low-pressure flames and differs from crossed molecular beams data. The accuracy of these isomer distributions is discussed in view of large uncertainties on the photoionization spectra of the pure C4H5 isomer