The causes for geographical variations in OS187/OS186 at the Cretaceous-Tertiary boundary

Researchers at Yale has approached the problem of the osmium isotopic composition of marine deposits formed in contact with both oxidized and reduced bottom waters. The measured (187) Os/(186) Os ratios of modern bulk sediment can be explained using mixing equations involving continental detrital, volcaniclastic, cosmogenic and hydrogeneous components. These studies show that sediments deposited under reducing marine conditions contain a hydrogenous component which is enriched in Re and has a radiogenic (187) Os/(186) Os ratio. The presence of such a hydrogenous component in the marine fish clay at Stevns Klint can account for the elevation of its (187) Os/(186) Os ration above the expected meteoritic value. Mass balance considerations require the Re/Os ratio of the phase precipitated from the terminal Cretaceous sea at Stevns Klint to have been about one tenth the value observed in contemporary deposits in the Black Sea, assuming Re has not been lost (or Os gained) subsequent to precipitation. In continental sections, the elevation of the (187) Os/(186) Os ratio in boundary layers may be due to precipitation from continental waters of crustally-derived radiogenic osmium either contemporaneous with the meteoritic (or mantle) osmium deposition or later during diagenesis

Measuring the upset of CMOS and TTL due to HPM-signals

To measure the performance of electronic components when stressed by High Power Microwave signals a setup was designed and tested which allows a well-defined voltage signal to enter the component during normal operation, and to discriminate its effect on the component.</p><p style=&quot;line-height: 20px;&quot;> The microwave signal is fed to the outside conductor of a coaxial cable and couples into the inner signal line connected to the device under test (DUT). The disturbing HF-signal is transferred almost independent from frequency to maintain the pulse shape in the time domain. The configuration designed to perform a TEM-coupling within a 50 Ohm system prevents the secondary system from feeding back to the primary system and, due to the geometrical parameters chosen, the coupling efficiency is as high as 50–90%. Linear dimensions and terminations applied allow for pulses up to a width of 12ns and up to a voltage level of 4–5 kV on the outside conductor. These pulse parameters proved to be sufficient to upset the DUTs tested so far.</p><p style=&quot;line-height: 20px;&quot;> In more than 400 measurements a rectangular pulse of increasing voltage level was applied to different types of CMOS and TTL until the individual DUT was damaged. As well the pulse width (3, 6 or 12 ns) and its polarity were varied in single-shot or repetitive-shot experiments (500 shots per voltage at a repetition rate of 3 Hz). The state of the DUT was continuously monitored by measuring both the current of the DUT circuit and that of the oscillator providing the operating signal for the DUT.</p><p style=&quot;line-height: 20px;&quot;> The results show a very good reproducibility within a set of identical samples, remarkable differences between manufacturers and lower thresholds for repetitive testing, which indicates a memory effect of the DUT to exist for voltage levels significantly below the single-shot threshold

Excitonic - vibronic coupled dimers: A dynamic approach

The dynamical properties of exciton transfer coupled to polarization vibrations in a two site system are investigated in detail. A fixed point analysis of the full system of Bloch - oscillator equations representing the coupled excitonic - vibronic flow is performed. For overcritical polarization a bifurcation converting the stable bonding ground state to a hyperbolic unstable state which is basic to the dynamical properties of the model is obtained. The phase space of the system is generally of a mixed type: Above bifurcation chaos develops starting from the region of the hyperbolic state and spreading with increasing energy over the Bloch sphere leaving only islands of regular dynamics. The behaviour of the polarization oscillator accordingly changes from regular to chaotic.Comment: uuencoded compressed Postscript file containing text and figures. In case of questions, please, write to [email protected]

Alcohol-Related Harms from Others' Drinking in India

Background: From 2005 to 2010, India faced a 19% increase in average adult per capita alcohol consumption. In a country where a large proportion of the population abstains from alcohol but heavy episodic consumption is common among those who drink, alcohol-related harms from others’ drinking may be substantial. Purpose: The purpose of this dissertation was to examine both the ethical issues raised in regards to harms from others drinking, and newly available epidemiological evidence about this in India. The main objectives were to: (1) apply a public health ethics framework to systematically consider the ethical implications of implementing policies to prevent alcohol-related harms to others; (2) understand the types of alcohol-related harms to children from adults’ drinking across domains of physical abuse, psychological abuse, and neglect; and (3) assess various types of tangible and intangible harm from strangers’ drinking and individuals’ characteristics that predict experiences of such harms. Methods: I examined public health ethics literature and generated evidence of harms from others’ drinking by analyzing cross-sectional data from household interviews administered in five Indian states in 2011-2012. Results: The compilation of data on harms from others’ drinking can strengthen the ethical justification for evidence-based alcohol control policies. Harms to children from adults’ drinking are a serious problem in India: 44% of respondents reported at least one alcohol-related harm to children in the past year. Sixteen percent of respondents reported physical alcohol-related harms to children. Strangers are also affected by others’ drinking: 63% of respondents experienced at least one tangible or intangible harm from strangers’ drinking, with nearly 48% of respondents experiencing tangible harm. Conclusions: Public health professionals have an obligation to consider the ethics associated with implementing alcohol control policies. The findings from this dissertation suggest that people with limited control over their exposure to another person’s drinking, including children and strangers, are burdened by others’ alcohol use. Interventions, such as increased use and enforcement of evidence-based alcohol control policies, are needed to prevent alcohol-related harms to children and strangers in India. Future research should use harms to others data for evaluating the effectiveness of alcohol policies

Effect of Length of Feeding Period of Performance of British and Exotic Crossbred Yearling Heifers

Producers very often question the additional length of time they should feed exotic-cross cattle as opposed to the feeding period required for the traditional British breeds of cattle. Also implied in this question in this question is the additional amount of feed needed for the exotic-cross animal to attain an optimum weight and an acceptable grade. This trial was conducted in an attempt to help answer these basic questions

Investigation and management of primary immunodeficiency in South African children

The primary immunodeficiency diseases (PIDs) are inherited, non-communicable diseases that cause immunological dysfunction. PIDs are seldom reported in South Africa (SA). Based on a mid-2013 population estimate of 52.98 million and assuming that the prevalence of PIDs is similar to that in well-resourced settings, the total number of individuals with PIDs in our country should range between2 850 and 45 723. However, fewer than 500 cases of PID have been reported in SA. Between five and 15 new, fully characterised PIDs are reported annually. Our understanding of the physiology of the immune system has been substantially enhanced by these discoveries, and consequently the international classification of PIDs has been updated

Development of an innovative validation strategy of gas–surface interaction modelling for re‑entry applications

Abstract This paper summarises the final synthesis of an ESA technology research programme entitled “Development of an Innovative Validation Strategy of Gas Surface Interaction Modelling for Re-entry Applications”. The focus of the project was to demonstrate the correct pressure dependency of catalytic surface recombination, with an emphasis on Low Earth Orbit (LEO) re-entry conditions and thermal protection system materials. A physics-based model describing the prevalent recombination mechanisms was proposed for implementation into two CFD codes, TINA and TAU. A dedicated experimental campaign was performed to calibrate and validate the CFD model on TPS materials pertinent to the EXPERT space vehicle at a wide range of temperatures and pressures relevant to LEO. A new set of catalytic recombination data was produced that was able to improve the chosen model calibration for CVD-SiC and provide the first model calibration for the Nickel–Chromium super-alloy PM1000. The experimentally observed pressure dependency of catalytic recombination can only be reproduced by the Langmuir–Hinshelwood recombination mechanism. Due to decreasing degrees of (enthalpy and hence) dissociation with facility stagnation pressure, it was not possible to obtain catalytic recombination coefficients from the measurements at high experimental stagnation pressures. Therefore, the CFD model calibration has been improved by this activity based on the low pressure results. The results of the model calibration were applied to the existing EXPERT mission profile to examine the impact of the experimentally calibrated model at flight relevant conditions. The heat flux overshoot at the CVDSiC/PM1000 junction on EXPERT is confirmed to produce radiative equilibrium temperatures in close proximity to the PM1000 melt temperature.This was anticipated within the margins of the vehicle design; however, due to the measurements made here for the first time at relevant temperatures for the junction, an increased confidence in this finding is placed on the computations

Методы автоматического поиска неисправностей и контроля сложных систем: обзор

In the face of continuously increasing cost pressure, a wide range of product versions and shorter innovation cycles, the demand for more versatile assembly and handling systems is steadily growing. Co-operating robots represent a suitable approach for this purpose. However, reconfiguring a multi-device robot cell usually involves a certain programming effort and unfavorable down times. By integrating self-optimizing functions, the complex task of reconfiguration is substantially simplified in order to make economic use not only of the referenced co-operating robotic systems. Therefore, several self-optimizing functions for different stages of production have been developed and applied to various production tasks. The implemented functions comprise self-optimizing planning and commissioning as well as a self-optimizing joining process. Based on the experience gained from these examples, the self-optimizing functions will be similarly applicable to various cases with rel atively small additional effort