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The terrestrialization of life has profoundly affected the biosphere, geosphere and atmosphere, and the Geological Magazine has published key works charting the development of our understanding of this process. Integral to this understanding – and featuring in one of the Geological Magazine publications – is the Devonian Rhynie chert Konservat-Lagerstätte located in Aberdeenshire, Scotland. Here we provide a review of the work on this important early terrestrial deposit to date. We begin by highlighting contributions of note in the Geological Magazine improving understanding of terrestrialization and Palaeozoic terrestrial ecosystems. We then introduce the Rhynie chert. The review highlights its geological setting: the Caledonian context of the Rhynie Basin and its nature at the time of deposition of the cherts which host its famous fossils. There follows an introduction to the development of the half-graben in which the cherts and host sediments were deposited, the palaeoenvironment this represented and the taphonomy of the fossils themselves. We subsequently provide an overview of the mineralization and geochemistry of the deposit, and then the fossils found within the Rhynie chert. These include: six plant genera, which continue to provide significant insights into the evolution of life on land; a range of different fungi, with recent work starting to probe plant–fungus interactions; lichens, amoebae and a range of unicellular eukaryotes and prokaryotes (algae and cyanobacteria); and finally a range of both aquatic and terrestrial arthropods. Through continued study coupled with methodological advances, Rhynie fossils will continue to provide unique insights into early life on land.
Insects have more than a million described species and represent more than half of all known living organisms. However, little is known about the operation and functions of the insect body, particularly their remarkable leg joints. This study is focused on partly filling this knowledge gap by using nanoindentation instruments to characterize the mechanical properties of leg joints from three different insects: a beetle, a mantis, and a dragonfly nymph. For all insect species, the tibia joint had the largest effective elastic moduli, followed by the femur joint, while the exocuticle had the smallest values.
X-ray diffraction topographs of modes in rectangular AT-cut quartz plates are shown. The change in the resulting patterns when different Bragg planes are used is demonstrated. Diffracted x -ray intensity was measured as a function of strain in a vibrating quartz plate . The Lame solutions for quartz plates are briefly described and some experiments suggested for x -ray topography. Finally modes in quartz plates with multiple electrodes are shown indicating the complexity of this type of vibration problem.
A controversy at the 2016 IUCN World Conservation Congress on the topic of closing domestic ivory markets (the 007, or so-called James Bond, motion) has given rise to a debate on IUCN's value proposition. A cross-section of authors who are engaged in IUCN but not employed by the organization, and with diverse perspectives and opinions, here argue for the importance of safeguarding and strengthening the unique technical and convening roles of IUCN, providing examples of what has and has not worked. Recommendations for protecting and enhancing IUCN's contribution to global conservation debates and policy formulation are given.
Firn-densification modeling based on hot isostatic pressing with power-law creep is investigated using depth–density data from 38 sites that collectively have mean annual temperatures ranging from 216 to 256 K and accumulation rates ranging from 0.022 to 1.2 m w.e. a−1. We use an inverse technique to obtain free parameters in a simple physical model for different stages of time-dependent firn densification. Our model works as well as or slightly better than previous models interpolating within the data range, but extrapolating would require additional physics.
SS433 has been under intensive study for the past five years in almost all wavelength bands of the electromagnetic spectrum. This peculiar object is generally regarded (Beer 1981) as being a binary system composed of a main sequence star losing mass via Roche lobe overflow to a massive accretion disk associated with a compact object, probably a neutron star. The binary period is 13.1 days. Supercritical accretion onto the disk causes about 10−6 M⊙/year of ionised matter to be ejected in the form of jets with a relatively constant velocity of 0.26 c along the disk axis. The disk (or the inner part of it) precesses with a period of about 164 days, although there is evidence that this may not be constant. The half angle of the precession cone is ~20° and its axis lies at an angle of ~80° to the line of sight. The main sequence star loses mass at a rate of 10−4 to 10−6 M⊙/yr into a stellar wind with the result that a relatively dense environment surrounds the binary system.
The galaxy M87 (3C274, NGC4486) contains one of the nearest jet sources in the northern hemisphere, and one of our best opportunities to study a jet in detail. We have made MkII VLBI observations of the nuclear jet at 1.66 GHz using 18 stations of the “World Array.” The array included Arecibo which greatly improved the north-south resolution. The data were global fringe fitted, and self-calibrated to remove both antenna and baseline amplitude and phase errors. The resulting map (Fig. 1) has a dynamic range of 2300:1 and reveals a very complex structure. At distances ≥50 mas from the core, the jet is resolved across its width and appears limb-brightened. The brightness centroid oscillates from side to side by an amount roughly equal to the jet's width; this may be caused by brightness variations at the edges of a limb-brightened jet. Within 50 mas of the core the opening angle (at the FWHM points) is 6.5°±0.3°; this is larger than that of the 20″ jet, and suggests there is recollimation between the pc and kpc scales. The jet is aligned within 1° of the 20″ jet. There is no evidence for a counter-jet; the jet/counter-jet brightness ratio is R≥200.
Compact Steep Spectrum (CSS) radio sources are defined as having straight steep spectra typical of extended double-lobed radio sources and structures unresolved by conventional interferometers (Peacock and Wall 1982; van Breugel et al., 1984; Fanti et al., 1985). Their spectra remain straight up to quite high frequencies, indicating that no dominant core is present. Sometimes the spectrum bends at frequencies lower than 1 GHz. The angular sizes imply projected linear sizes generally < 10 kpc.
SS433 is thought to be a binary system from which two antiparallel beams are ejected at 0.26c. An excellent review of this peculiar object has been given by Margon (1984). The so-called “kinematic model” describes the precessing motion of the beams. They can be obcervef over at least 8 orders of magnitude in distance: from 1012 cm to 1020 cm.
The WAIS (West Antarctic Ice Sheet) Divide deep ice core was recently completed to a total depth of 3405 m, ending 50 m above the bed. Investigation of the visual stratigraphy and grain characteristics indicates that the ice column at the drilling location is undisturbed by any large-scale overturning or discontinuity. The climate record developed from this core is therefore likely to be continuous and robust. Measured grain-growth rates, recrystallization characteristics, and grain-size response at climate transitions fit within current understanding. Significant impurity control on grain size is indicated from correlation analysis between impurity loading and grain size. Bubble-number densities and bubble sizes and shapes are presented through the full extent of the bubbly ice. Where bubble elongation is observed, the direction of elongation is preferentially parallel to the trace of the basal (0001) plane. Preferred crystallographic orientation of grains is present in the shallowest samples measured, and increases with depth, progressing to a vertical-girdle pattern that tightens to a vertical single-maximum fabric. This single-maximum fabric switches into multiple maxima as the grain size increases rapidly in the deepest, warmest ice. A strong dependence of the fabric on the impurity-mediated grain size is apparent in the deepest samples.
Valid consent for treatment or research participation requires that an individual has decision-making capacity (DMC), which is the ability to make a specific decision. There is evidence that the psychopathology of schizophrenia can compromise DMC. The objective of this review was to examine the presence or absence of DMC in schizophrenia and the socio-demographic/psychopathological factors associated.
We searched three databases Embase, Ovid MEDLINE(R), and PsycINFO for studies reporting data on the proportion of DMC for treatment and research (DMC-T and DMC-R), and/or socio-demographic/psychopathological associations with ability to make such decisions, in people with schizophrenia and related illnesses.
A total of 40 studies were identified. While high levels of heterogeneity limited direct comparison, meta-analysis of inpatient data showed that DMC-T was present in 48% of people. Insight was strongly associated with DMC-T. Neurocognitive deficits were strongly associated with lack of DMC-R and to a lesser extent DMC-T. With the exception of years of education, there was no evidence for an association with socio-demographic factors.
Insight and neurocognitive deficits are most closely associated with DMC in schizophrenia. The lack of an association with socio-demographic factors dispels common misperceptions regarding DMC and characteristics such as age. Although our results reveal a wide spectrum of DMC-T and DMC-R in schizophrenia, this could be partly due to the complexity of the DMC construct and the heterogeneity of existing studies. To facilitate systematic review research, there is a need for improvement within research study design and increased consistency of concepts and tools.
A plausible mechanism underlying flavonoid-associated cognitive effects is increased cerebral blood flow (CBF). However, behavioural and CBF effects following flavanone-rich juice consumption have not been explored. The aim of this study was to investigate whether consumption of flavanone-rich juice is associated with acute cognitive benefits and increased regional CBF in healthy, young adults. An acute, single-blind, randomised, cross-over design was applied with two 500-ml drink conditions – high-flavanone (HF; 70·5 mg) drink and an energy-, and vitamin C- matched, zero-flavanone control. A total of twenty-four healthy young adults aged 18–30 years underwent cognitive testing at baseline and 2-h after drink consumption. A further sixteen, healthy, young adults were recruited for functional MRI assessment, whereby CBF was measured with arterial spin labelling during conscious resting state at baseline as well as 2 and 5 h after drink consumption. The HF drink was associated with significantly increased regional perfusion in the inferior and middle right frontal gyrus at 2 h relative to baseline and the control drink. In addition, the HF drink was associated with significantly improved performance on the Digit Symbol Substitution Test at 2 h relative to baseline and the control drink, but no effects were observed on any other behavioural cognitive tests. These results demonstrate that consumption of flavanone-rich citrus juice in quantities commonly consumed can acutely enhance blood flow to the brain in healthy, young adults. However, further studies are required to establish a direct causal link between increased CBF and enhanced behavioural outcomes following citrus juice ingestion.
Early arterial phase imaging is critical for high-quality CT angiography examinations; however, accurate imaging can be problematic in patients with large aneurysms or aortic dissections. In some cases, an early arterial acquisition may not allow enough time for complete filling of the aneurysm sac or false lumen with contrast (Figures 54.1–54.3). The incompletely opacified aneurysm sac or false lumen may appear thrombosed, when in actuality it is merely filled with unopacified blood. Swirling of contrast within the aneurysm sac is often present and can be a clue that incomplete contrast filling has occurred (Figure 54.3).
In the patient with acute pain, large aneurysms must be evaluated for signs of instability or rupture. One of the most critical findings is contrast extravasation reflective of active hemorrhage, which requires immediate repair. The case shown here (Figure 54.1) demonstrates how this important finding could be missed if the arterial timing did not allow for complete aneurysm filling.
Patients with aortic dissection may have very slow flow in the false lumen, resulting in the appearance of pseudothrombosis of both the false lumen and the branches that arise from this lumen. As shown by the second case (Figure 54.2), a longer imaging delay will elucidate that the false lumen, arterial branch and end organ are actually perfused. The distinction is important because in the setting of arterial thrombosis intervention is necessary, whereas uncomplicated type B dissections do not require endovascular or surgical repair.
Although much less common, proper characterization of a coronary artery aneurysm (Figure 54.3) as patent or thrombosed is critical to determine whether repair is indicated to avert rupture.
Typical clinical scenario
Aortic aneurysms and dissections are two of the most common forms of aortic pathology. Patients may present acutely with pain, or may undergo serial imaging to guide management of previously diagnosed aneurysm or partially repaired dissection. Coronary aneurysms are much less common, particularly larger aneurysms. In adults, atherosclerosis is the most common cause, whereas in children it is Kawasaki disease.
Surveys of chronic health conditions provide information about prevalence but not incidence and the process of change within the population. Our study shows how “age dynamics” of chronic conditions – the probabilities of contracting conditions at different ages, of moving from one chronic condition state to another, and of dying – can be inferred from prevalence data for those conditions that can be viewed as irreversible. Transition probability matrices are constructed for successive age groups, with the sequence representing the age dynamics of the health conditions for a stationary population. We simulate the life path of a cohort under the initial probabilities, and again under altered probabilities, to explore the effects of reducing the incidence or mortality rate associated with a particular condition. We show that such surveys of chronic conditions can be made even more valuable by allowing the calculation of the transition probabilities that define the chronic conditions aging process
Effects of a marine oil-based n-3 LCPUFA supplement (mLCPUFA) fed from weaning until the end of the next lactation to sows with a predicted low litter birth weight (LBW) phenotype on growth performance and carcass quality of litters born to these sows were studied, based on the hypothesis that LBW litters would benefit most from mLCPUFA supplementation. Sows were allocated to be fed either standard corn/soybean meal-based gestation and lactation diets (CON), or the same diets enriched with 0.5% of the mLCPUFA supplement at the expense of corn. The growth performance from birth until slaughter of the litters with the lowest average birth weight in each treatment (n=24 per treatment) is reported in this paper. At weaning, each litter was split between two nursery pens with three to six pigs per pen. At the end of the 5-week nursery period, two barrows and two gilts from each litter that had individual birth weights closest to their litter average birth weight, were moved to experimental grow–finish pens (barn A), where they were housed as two pigs per pen, sorted by sex within litter. Remaining pigs in each litter were moved to another grow–finish barn (barn B) and kept in mixed-sex pens of up to 10 littermates. After 8 weeks, one of the two pigs in each pen in barn A was relocated to the pens holding their respective littermates in barn B. The remaining barrows and gilts were individually housed in the pens in barn A until slaughter. Maternal mLCPUFA supplementation increased docosahexaenoic acid (DHA) concentration in the brain, liver and Semitendinosus muscle of stillborn pigs (P<0.01), did not affect eicosapentaenoic acid and DHA concentrations in sow serum at the end of lactation, and did not affect average daily gain, average daily feed intake or feed utilization efficiency of the offspring. BW was higher (P<0.01) in the second half of the grow–finish phase in pigs from mLCPUFA sows compared with controls in barn A, where space and competition for feed was minimal, but not barn B. Carcass quality was not affected by treatment for pigs from barn A, but maternal mLCPUFA supplementation negatively affected carcass quality in pigs from barn B. Collectively, these results suggest that nutritional supplementation of sows can have lasting effects on litter development, but that feeding mLCPUFA to sows during gestation and lactation was not effective in improving growth rates or carcass quality of LBW litters.