973 resultados para 130-804
Resumo:
The Neogene carbonate stratigraphy of five sites drilled on Ontong Java Plateau during Leg 130 reveals a number of patterns which are unexpected, and which we refer to as loss paradox, equatorial insensitivity, and climate paradox. They denote the following unresolved questions. 1 The loss of carbonate at depth (as derived from differences in accumulation rates) is much greater than suggested by the change in carbonate percentages (calculated under the assumption that carbonate dissolution is the cause of loss). This indicates an important role for redeposition processes, such as winnowing (bottom currents), sifting (resuspension and catabatic flow) and episodic sloughing or solifluction (presumably stimulated by earthquakes). 2 Accumulation rates are not markedly increased at the time a site crosses the equator. There are several possible reasons. Equatorial upwelling may be unimportant in controlling sedimentation rates this far in the western Pacific, or its output may be spread over a considerable distance from the equator. Alternatively, increased supply below the equator is compensated for by increased removal (e.g. from resuspension by bioturbation, combined with catabatic flow). It is conceivable that errors in the timescale could also produce the effect seen. 3 There is an overall tendency for agreement between the stratigraphic patterns of carbonate content and of accumulation rates, but neither pattern is readily explained by reference to changes in climate (represented by benthic delta18O) or in sea-level (as derived from sequence stratigraphy).
Resumo:
Consolidation tests were performed on 19 samples of calcareous ooze from the Ontong Java Plateau, obtained during Ocean Drilling Program Leg 130. Rebound curves from consolidation tests on Ontong Java Plateau samples yield porosity rebounds of 1%-4% for these sediments at equivalent depths up to 1200 mbsf. The exception is a radiolarian-rich sample that has 6% rebound. A rebound correction derived from the porosity rebound vs. depth data has been combined with a correction for pore-water expansion to correct the shipboard laboratory porosity data to in-situ values. Comparison of the laboratory porosity data corrected in this manner with the downhole log data shows good agreement.
Resumo:
We investigated minor element ratios (Sr/Ca and Mg/Ca) in bulk sediment samples from Sites 803-807 using a recently optimized sample treatment protocol for calcium-carbonate-rich sediments consisting of sequential reductive and ion exchange treatments. We evaluated this protocol relative to bulk sediment leaching using samples from Sites 804 and 806, the two end-member sites in the depth transect, reporting as well Mn/Ca and Fe/Ca ratios for sediments from these two sites processed by means of both methods. The Sr/Ca ratios were only slightly affected by the sample treatment, with an average reduction of 6%-7% caused primarily by the ion exchange step. The reductive sample treatment, designed to be effective at removing Mn-rich oxyhydroxides, has a major effect on Mg/Ca ratios, with up to 50% reduction, whereas little effect occurred in ion exchange alone on Mg/Ca ratios. The Mn/Ca and Fe/Ca ratios were not consistently offset by the sample treatment, and these ratios do not appear to be representative of calcite geochemistry reflecting either ocean history or diagenetic overprinting. Celestite solubility appears to be an important control on interstitial water Sr concentrations in these sites, and it must be considered when constructing Sr mass balance models of calcite recrystallization. Calcite Sr/Ca ratios (range 1-2 mmol/mol) are similar from site to site when plotted vs. age, with a pattern comparable to that for well-preserved foraminifer tests over the past 40 Ma. Interstitial water Mg and Ca gradients appear to reflect basement character and the intensity of alteration; they can vary substantially over a small area. Calcite Mg/Ca ratios (range 1.5-4.5 mmol/mol) differ from site to site, with generally higher ratios for sites at a shallower water depth. Increasing calcite Mg/Ca ratios correlate with decreasing Sr/Ca ratios in the treated samples. No consistent pattern exists for calcite Mg/Ca ratios vs. age or depth, nor is any direct correlation to interstitial water Mg/Ca ratios present.
Resumo:
This article examines some questions of statutory interpretation as they apply to section 130 of the Land Title Act 1994 (Qld)
Resumo:
A series of observational studies have been made to investigate the association of the ADAM33 gene polymorphisms with the risk of COPD, but their results were conflicting. Therefore, we performed an updated meta-analysis to quantitatively summarize the associations of ADAM33 gene polymorphisms with the risk of COPD. Thirteen case–control studies referring to nine SNPs were identified: V4 (rs2787094), T+1 (rs2280089), T2 (rs2280090), T1 (rs2280091), S2 (rs528557), S1 (rs3918396), Q−1 (rs612709), F+1 (rs511898) and ST+5 (rs597980). A dominant model (AA+Aa vs. aa), recessive model (AA vs. Aa+aa), additive model (AA vs. aa) and allelic model (A vs. a) were used to evaluate the association of ADAM33 polymorphism with the risk of COPD. The results indicated that significant associations were found for ADAM33 T1, T2, S1, Q−1, F+1 and ST+5 polymorphisms associated with the risk of COPD in different populations. However, no significant associations were found for V4, T+1 and S2 polymorphisms with the risk of COPD in all genetic models, even in the subgroup analysis by ethnicity. This meta-analysis provided evidence that the ADAM33 T1, T2, S1, Q−1, F+1 and ST+5 six locus polymorphisms association with the risk of COPD. Furthermore, T2, Q−1 and ST+5 indicated an association with the risk of COPD in the European populations, whereas T1, T2, S1, F+1 and Q−1 indicated an association with the risk of COPD in the Asian populations.
Resumo:
We report the growth of nanowires of the charge transfer complex tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) with diameters as low as 130 nm and show that such nanowires can show Peierls transitions at low temperatures. The wires of sub-micron length were grown between two prefabricated electrodes (with sub-micron gap) by vapor phase growth from a single source by applying an electric field between the electrodes during the growth process. The nanowires so grown show a charge transfer ratio similar to 0.57, which is close to that seen in bulk crystals. Below the transition the transport is strongly nonlinear and can be interpreted as originating from de-pinning of CDW that forms at the Peierls transition.
Resumo:
This paper presents a modified design method for linear transconductor circuit in 130 nm CMOS technology to improve linearity, robustness against process induced threshold voltage variability and reduce harmonic distortion. Source follower in the adaptively biased differential pair (ABDP) linear transconductor circuit is replaced with flipped voltage follower to improve the efficiency of the tail current source, which is connected to a conventional differential pair. The simulation results show the performance of the modified circuit also has better speed, noise performance and common mode rejection ratio compared to the ABDP circuit.
Resumo:
We report a Raman study of single crystal pyrochlore Er(2)Ti(2)O(7) as a function of temperature from 12 to 300 K. In addition to the phonons, various photoluminescence (PL) lines of Er(3+) in the visible range are also observed. Our Raman data show an anomalous red-shift of two phonons (one at similar to 200 cm(-1) and another at similar to 520 cm(-1)) upon cooling from room temperature which is attributed to phonon-phonon anharmonic interactions. However, the phonons at similar to 310, 330, and 690 cm(-1) initially show a blue-shift upon cooling from room temperature down to about 130 K, followed by a red-shift, indicating a structural deformation at similar to 130 K. The intensities of the PL bands associated with the transitions between the various levels of the ground state manifold ((4)I(15/2)) and the (2)H(11/2) as well as (4)S(3/2) excited state manifolds of Er(3+) show a change at similar to 130 K. Moreover, the temperature dependence of the peak position of the two PL bands shows a change in their slope (d(omega)/d(T)) at similar to 130 K, thus further strengthening the proposal of a structural deformation. The temperature dependence of the peak positions of the PL bands has been analyzed using the theory of optical dephasing in crystals.
Resumo:
Chronic recording of neural signals is indispensable in designing efficient brain–machine interfaces and to elucidate human neurophysiology. The advent of multichannel micro-electrode arrays has driven the need for electronics to record neural signals from many neurons. The dynamic range of the system can vary over time due to change in electrode–neuron distance and background noise. We propose a neural amplifier in UMC 130 nm, 1P8M complementary metal–oxide–semiconductor (CMOS) technology. It can be biased adaptively from 200 nA to 2 $mu{rm A}$, modulating input referred noise from 9.92 $mu{rm V}$ to 3.9 $mu{rm V}$. We also describe a low noise design technique which minimizes the noise contribution of the load circuitry. Optimum sizing of the input transistors minimizes the accentuation of the input referred noise of the amplifier and obviates the need of large input capacitance. The amplifier achieves a noise efficiency factor of 2.58. The amplifier can pass signal from 5 Hz to 7 kHz and the bandwidth of the amplifier can be tuned for rejecting low field potentials (LFP) and power line interference. The amplifier achieves a mid-band voltage gain of 37 dB. In vitro experiments are performed to validate the applicability of the neural low noise amplifier in neural recording systems.