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Investigations into the existence of life in other parts of the cosmos find strong parallels with studies of the origin and evolution of life on our own planet. In this way, astrobiology and paleobiology are married by their common interest in disentangling the interconnections between life and the surrounding environment. In this way, a cross-point of both sciences is paleometry, which involves a myriad of imaging and geochemical techniques, usually non-destructive, applied to the investigation of the fossil record. In the last decades, paleometry has benefited from an unprecedented technological improvement, thus solving old questions and raising new ones. This advance has been paralleled by conceptual approaches and discoveries fuelled by technological evolution in astrobiological research. In this context, we present some new data and review recent advances on the employment of paleometry to investigations on paleobiology and astrobiology in Brazil in areas such biosignatures in Ediacaran microbial mats, biogenicity tests on enigmatic Ediacaran structures, research on Ediacaran metazoan biomineralization, fossil preservation in Cretaceous insects and fish, and finally the experimental study on the decay of fish to test the effect of distinct types of sediment on soft-tissue preservation, as well as the effects of early diagenesis on fish bone preservation.
This paper presents a fully-integrated direct-conversion fundamentally-operated mixer-first quadrature receiver module with a tunable LO in the 219–266 GHz band. It has been implemented in a 0.13-μm SiGe heterojunction bipolar transistor technology. It includes an on-chip LO path driven externally from the printed circuit board (PCB) connector level at 13.6–16.7 GHz. A hybrid coupler generates the quadrature LO signal, which drives a pair of double-balanced fundamentally-operated down-conversion mixers, whose RF ports are connected to a wideband lens-integrated on-chip ring antenna. The chip-on-lens assembly is placed in the recess of a high-speed PCB and wire-bonded. To compensate the inductive behavior of the wire-bond interconnection between the chip and the PCB at the high-speed IF outputs, an on-board 8-section step-impedance low-pass filter has been implemented. The module shows a 47 GHz 3-dB radio frequency/local oscillator operation bandwidth (BW), a peak conversion gain of 7.8 dB, a single-side-band noise figure of 11.3 dB, and a 3-dB IF BW of 13 GHz. The in-phase and quadrature amplitude imbalance stays below 1.58 dB for the 210–280 GHz band. The down-conversion and the baseband stages consume together 75.5 mW, while the LO path 378 mW. The maximum data-rate achieved with this receiver in combination with the transmitter presented in [1–3] is 60 Gbps for quadrature phase shift keying modulation.
Major depression and anxiety disorders are known to negatively influence cognitive performance. Moreover, there is evidence for greater cognitive decline in older adults with generalized anxiety disorder. Except for clinical studies, complex executive planning functions and subclinical levels of anxiety have not been examined in a population-based sample with a broad age range.
Planning performance was assessed using the Tower of London task in a population-based sample of 4240 participants aged 40–80 years from the Gutenberg Health Study (GHS) and related to self-reported anxiety and depression by means of multiple linear regression analysis.
Higher anxiety ratings were associated with lower planning performance (β = −0.20; p < 0.0001) independent of age (β = 0.03; p = 0.47). When directly comparing the predictive value of depression and anxiety on cognition, only anxiety attained significance (β = −0.19; p = 0.0047), whereas depression did not (β = −0.01; p = 0.71).
Subclinical levels of anxiety but not of depression showed negative associations with cognitive functioning independent of age. Our results demonstrate that associations observed in clinical groups might differ from those in population-based samples, also with regard to the trajectory across the life span. Further studies are needed to uncover causal interrelations of anxiety and cognition, which have been proposed in the literature, in order to develop interventions aimed at reducing this negative affective state and to improve executive functioning.
Animal health surveillance enables the detection and control of animal diseases including zoonoses. Under the EU-FP7 project RISKSUR, a survey was conducted in 11 EU Member States and Switzerland to describe active surveillance components in 2011 managed by the public or private sector and identify gaps and opportunities. Information was collected about hazard, target population, geographical focus, legal obligation, management, surveillance design, risk-based sampling, and multi-hazard surveillance. Two countries were excluded due to incompleteness of data. Most of the 664 components targeted cattle (26·7%), pigs (17·5%) or poultry (16·0%). The most common surveillance objectives were demonstrating freedom from disease (43·8%) and case detection (26·8%). Over half of components applied risk-based sampling (57·1%), but mainly focused on a single population stratum (targeted risk-based) rather than differentiating between risk levels of different strata (stratified risk-based). About a third of components were multi-hazard (37·3%). Both risk-based sampling and multi-hazard surveillance were used more frequently in privately funded components. The study identified several gaps (e.g. lack of systematic documentation, inconsistent application of terminology) and opportunities (e.g. stratified risk-based sampling). The greater flexibility provided by the new EU Animal Health Law means that systematic evaluation of surveillance alternatives will be required to optimize cost-effectiveness.
Cover crop-based reduced tillage (CCBRT) has achieved positive impacts in organic row crop systems, contributing to the conservation of soil resources and the facilitation of weed management. This technique, which uses cover crop residues as mulches to suppress weeds, has shown more variable success in organic vegetable production systems. This experiment examined CCBRT for small-scale organic vegetable production in the upper Midwestern USA, specifically evaluating weed suppression, labor inputs and crop yields. Cereal rye (Secale cereale L.) and winter wheat (Triticum aestivum L.) were fall-sown in 2012 and 2013 in a strip-plot design, including control treatments with no cover crop and spring-applied oat straw mulch. Cover crop plots were strip-tilled in mid-April to establish a planting zone, with cover crops terminated in late May at anthesis with a hand-tractor mounted sickle-bar mower. Bell peppers (Capsicum annuum L. var. ‘Revolution’), snap beans (Phaseolus vulgaris L. var. ‘Tavera’), and potatoes (Solanum tuberosum L. var. ‘Red La Soda’) were hand-planted either as transplants or seed in each treatment immediately following cover crop termination. During each summer growing season, weeds were completely eliminated from each plot by hand approximately every 10–14 days, with time for manual weeding recorded for each treatment. Vegetable crop yields and quality were measured at harvest during 2013 and 2014. Cereal rye and winter wheat produced similar biomass at the time of termination. Greater weed biomass was collected in the wheat treatment as compared with the cereal rye, increasing the in-season labor required for manual weeding. Bean yields were decreased in the all CCBRT treatments compared with control treatments in both years of the study. Pepper yields did not differ in CCBRT treatments as compared with the control in both 2012 and 2013, although the CCBRT treatments did yield lower marketable peppers compared with the straw mulch plots. Potato tuber yields were not different in the CCBRT treatments as compared with the control in 2012, but were lower in 2013. These data indicate that, if CCBRT is to be more widely adopted in small-scale vegetable production, further optimization of the system must be achieved to ensure consistent and adequate weed suppression while maintaining crop yield and quality.
The ZZ Ceti stars form a class of variable white dwarfs: the hydrogen dominated atmosphere ones, which do pulsate in an instability strip in the effective temperature range 13000K-11500K. We know 22 such ZZ Ceti white dwarfs. Their variations are caused by nonradial g-mode pulsations with periods are in the range 100-1000 seconds.
A subsample of the ZZ Ceti stars shows amplitude variations on time scales of the order of one month. These variations could be driven by nonlinear phenomena.
At Pennsylvania’s Flower and Cook Observatory, instrumentation has been developed to measure simultaneously the four Stokes parameters of the filtered radiation field from a celestial source. The instrumental Q/U/V-parameters have been found to be very small and well-behaved. Thus far, the program has concentrated on cool bright giants and supergiants and on hot, evolving close binaries. A single season’s investigation of Alp Ori has already been reported (Holenstein 1987) and the present paper is a summary of current results for the cool, evolved program stars.
For Psi1 Aur, V CVn, 6 Gem, 72 Leo and 119 Tau no V-signal at the level of 3σhas been detected from data from the 1986-1987 season. At the level of 0.0n%, unambiguous and variable V-signals have been detected for VV Cep, Mu Cep, Alp Her, Alp Ori, Bet Peg, and Alp Sco.
A 240-GHz monostatic circular polarized SiGe frequency-modulated continuous wave radar system based on a transceiver chip with a single on-chip antenna is presented. The radar transceiver front-end is implemented in a low-cost 0.13 µm SiGe HBT technology version with cut-off frequencies fT/fmax of 300/450 GHz. The transmit block comprises a wideband ×16 frequency multiplier chain, a three-stage PA, while the receive block consists of a low-noise amplifier, a fundamental quadrature down-conversion mixer, and a three-stage PA to drive the mixer. A differential branch-line coupler and a differential dual-polarized on-chip antenna are added on-chip to realize a fully integrated radar transceiver. All building blocks are implemented fully differential. The use of a single antenna in the circular polarized radar transceiver leads to compact size and high sensitivity. The measured peak-radiated power from the Si-lens equipped radar module is +11 dBm (equivalent isotropically radiated power) at 246 GHz and noise figure is 21 dB. The characterization bandwidth of the radar transceiver is 60 GHz around the center frequency of 240 GHz, and the simulated Tx-to-Rx leakage is below −20 dB from 230 to 260 GHz. After system calibration the resolution of the system to distinguish between two targets at different distance of 3.65 mm is achieved, which is only 21% above the theoretical limit.
In this globalized world, the spread of new, exotic and re-emerging diseases has become one of the most important threats to animal production and public health. This systematic review analyses conventional and novel early detection methods applied to surveillance. In all, 125 scientific documents were considered for this study. Exotic (n = 49) and re-emerging (n = 27) diseases constituted the most frequently represented health threats. In addition, the majority of studies were related to zoonoses (n = 66). The approaches found in the review could be divided in surveillance modalities, both active (n = 23) and passive (n = 5); and tools and methodologies that support surveillance activities (n = 57). Combinations of surveillance modalities and tools (n = 40) were also found. Risk-based approaches were very common (n = 60), especially in the papers describing tools and methodologies (n = 50). The main applications, benefits and limitations of each approach were extracted from the papers. This information will be very useful for informing the development of tools to facilitate the design of cost-effective surveillance strategies. Thus, the current literature review provides key information about the advantages, disadvantages, limitations and potential application of methodologies for the early detection of new, exotic and re-emerging diseases.
Declines in Old World vulture populations have been linked to anthropogenic pressures. To assess these threats, the social dimensions of vulture conservation must be explored. Prior research in Africa focused on commercial farmers’ perceptions of vultures and identified that small stock farmers used poison more than large stock farmers to deter livestock predators. However, the vulnerable Cape Vulture Gyps coprotheres breeds throughout communal farmland in the Eastern Cape Province, South Africa. Consequently, community interviews were conducted within the foraging range of the Msikaba Cape Vulture colony, separating regions according to the amount of transformed land. Residents in the least transformed land region perceived the smallest reductions in livestock ownership over the past ten years, while residents of the moderately transformed region perceived the greatest reductions in livestock ownership. Livestock carcasses were reported to be available for vultures at ‘informal vulture restaurants’. Arrangement of livestock carcasses was found to be independent of land use; however type of carcass consumed varied. None of the respondents stated they used poison to eliminate livestock predators. More respondents cited illegal poaching of vultures for traditional medicine as a threat, although the majority stated that vultures benefited the community.
Laser processing of thin-film silicon is a promising approach for the realization of polycrystalline silicon for large area electronics and solar cell applications. In this study we investigate the material modification of amorphous hydrogenated silicon (a-Si:H) with different hydrogen content (30%, 13% and <1%) by means of femtosecond (fs) laser pulses. Depending on the peak fluence applied, hydrogen diffusion/effusion, layer crystallization or material ablation can be achieved. Despite the low absorption coefficient of a-Si:H at the center wavelength of an amplified Titanium Sapphire laser at 790 nm a high local energy deposition close to the surface of the a-Si:H layer is observed, which can be attributed to a nonlinear absorption process.
We have performed large-scale nucleosynthesis calculations within the high-entropy-wind (HEW) scenario of Type II supernovae. The primary aim was to constrain the conditions for the production of the classical ‘p-only’ isotopes of the light trans-Fe elements. We find, however, that for electron fractions in the range 0.458 ≤ Ye ≤ 0.478, sizeable abundances of p-, s- and r-process nuclei between 64Zn and 98Ru are coproduced in the HEW at low entropies (S ≤ 100) by a primary charged-particle process after an α-rich freezeout. With the above Ye–S correlation, most of the predicted isotopic abundance ratios within a given element, e.g. 64Zn(p)/70Zn(r) or 92Mo(p)/94Mo(p), as well as of neighboring elements, e.g. 70Ge(s + p)/74Se(p) or 74Se(p)/78Kr(p) agree with the observed Solar-System ratios. Taking the Mo isotopic chain as a particularly challenging example, we show that our HEW model can account for the production of all 7 stable isotopes, from ‘p-only’ 92Mo, via ‘s-only’ 96Mo up to ‘r-only’ 100Mo. Furthermore, our model is able to reproduce the isotopic composition of Mo in presolar SiC X-grains.
Traumatized individuals and particularly post-traumatic stress disorder (PTSD) patients are characterized by memory disturbances that suggest altered memory control. The present study investigated the issue using an item method, directed forgetting (DF) paradigm in 51 civil war victims in Uganda. All participants had been exposed to severe traumatic stress and 26 additionally suffered from PTSD.
In an item cued, DF paradigm photographs were presented, each followed by an instruction to either remember or forget it. A recognition test for all initially presented photographs and thematically similar distracters followed. DF patterns were compared between the non-PTSD and the PTSD groups. Post-experimental ratings of picture valence and arousal were collected and correlated with DF.
Results revealed DF, that is, reduced recognition for ‘to-be-forgotten’ items in the non-PTSD but not in the PTSD group. Moreover, in the non-PTSD, but not in the PTSD group, false alarms were reduced for ‘to-be-remembered’ items. Finally, DF was reduced in those participants who rated the pictures as more arousing, the PTSD group giving, on average, higher arousal ratings.
Data indicate that DF is reduced in PTSD and that the reduction is related to stimulus arousal. Furthermore, individuals with PTSD are characterized by a more global encoding style than individuals without PTSD, reflected in a higher false alarm rate. In sum, traumatized individuals with (but not without) PTSD are impaired in their ability to selectively control episodic memory encoding. This impairment may contribute to clinical features of the disorder such as intrusions and flashbacks.
A high—performance, cost—effective silicon—on—insulator (SOI) technology would have important near—term applications in radiation—hardened electronics and longer term applications in submicrometer VLSI. The advantages of SOI over bulk Si technology for these applications will be outlined, and CMOS, CJFET, andbipolar device structures being developed for SOI will be discussed. The current status and future prospects of the two most promising SOI technologies —— beam recrystallization and high—dose oxygen implantation —— will be reviewed, with emphasis on such issues critical to commercialization as material quality and manufacturing feasibility.
A seeded channel approach was developed to avoid the short comings of the conventional SOI structure such as grain or sub-grain boundaries in the channel region, floating substrate effects, etc. In this approach, the gate of each FET is located above its own seed window to insure that single crystalline material is obtained for the channel region. The source and drain regions, however, are located in the recrystallized silicon over Si02 for improved isolation and minimizing junction capacitance. Recrystallization was obtained in 4" silicon wafers by using an Ar laser and a computer controlled X-Y stage with heated substrate holder. Problems encountered in laser recrystallization, such as, reflectivity variations over seed and SOI regions, surface ripples, pittings, etc., were eliminated by optimizing the thin film thickness of the isolation oxide, polysilicon, and the capping oxide. This technology was used successfully to fabricate FET devices using a standard production n-MOS process. Good device characteristics were obtainred using 400Å gate oxide and channel length ranging from 1um to 50um. The measured electron mobility in the channel region is, however still lower than the ideal bulk values.
The microstructure of beam recrystallized silicon-on-insulator (SOI) films is strongly dependent on nucleation and growth processes during zone-melt propagation. In general, the recrystallization takes place along the (100) plane and in the <001> direction and in this case subgrain boundaries form the only major defects in the material. We have, however, identified stable growth regimes that produce predominantly twin boundaries, when the SOl films recrystallize with their surface parallel to the (110) planes. The twin formation process is attributed to growth twinning characteristic for f.c.c. and diamond structures. It has been established that the majority of these boundaries consist of coherent twins. In this manner (110) textured SOl films can be grown which contain almost entirely twin boundaries as structural defects. The crystallography of coherent twin boundaries in SOI films and their dependence on growth parameters is presented.
Multiple layers of silicon on insulator have been recrystallized using a dual electron beam technique. The aim of the investigations was to produce structures suitable for three dimensional circuit applications, and so a number of strategies have been used, providing a range of opportunities for such applications. In particular, two layers of silicon on insulator have been recrystallized simultaneously, and also a second layer has been recrystallized, seeded from a previously regrown film.
The effects of post implantation annealing on the properties of buried oxide silicon-on-insulator (SOI) substrates in the temperature range of 1150°C to 1300°C have been studied. Microstructural analyses showed that the crystallinity of the top silicon layer was improved at higher annealing temperature. Lower thermal donor generation at 450°C was observed in SOI annealed at higher temperature. The improvement in microstructure and lower thermal donor generation were correlated to the lower oxygen concentration in the top silicon film.
Since the introduction of zone-melting recrystallization (ZMR)for silicon-on-insulator (SOI) films, subboundaries (low-angle grain boundaries) have been the major crystalline defects in recrystallized films. By using an improved ZMR procedure, subboundaries have been eliminated over large areas. The improvements include the use of 1-µm-thick polycrystalline-Si films deposited on 2-µm-thick thermal SiO2 film (instead of 0.5-µm-thick Si and SiO2 films), a new encapsulation technique, and improved control of the thermal gradient during ZMR. Recrystallized SOI films without subboundaries contain isolated dislocations with densities <2 × 106 cm−2.
We present evidence on the types of structural changes caused by the rapid thermal annealing of two types of heteroepitaxial layers: CaF2/CoSi2/Si(111) and Si(100) on A12O3 (1102). We find that grains in a film can be merged into a single crystal and that the microtwin density can be dramatically lowered. We also find a number of changes in the structure of the heteroepitaxial interfaces.