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This chapter reviews the state of our knowledge about Saturn’s polar atmosphere that has been revealed through Earth- and space-based observation as well as theoretical and numerical modeling. In particular, the Cassini mission to Saturn, which has been in orbit around the ringed planet since 2004, has revolutionized our understanding of the planet. The current review updates a previous review by Del Genio et al. (2009), written after Cassini’s primary mission phase that ended in 2008, by focusing on the north polar region of Saturn and comparing it to the southern high latitudes. Two prominent features in the northern high latitudes are the northern hexagon and the north polar vortex; we extensively review observational and theoretical investigations to date of both features. We also review the seasonal evolution of the polar regions using the observational data accumulated during the Cassini mission since 2004 (shortly after the northern winter solstice in 2002), through the equinox in 2009, and approaching the next solstice in 2017. We conclude the current review by listing unanswered questions and describing the observations of the polar regions planned for the Grand Finale phase of the Cassini mission between 2016 and 2017.
The longevity of Cassini’s exploration of Saturn’s atmosphere (a third of a Saturnian year) means that we have been able to track the seasonal evolution of atmospheric temperatures, chemistry and cloud opacity over almost every season, from solstice to solstice and from perihelion to aphelion. Cassini has built upon the decades-long ground-based record to observe seasonal shifts in atmospheric temperature, finding a thermal response that lags behind the seasonal insolation with a lag time that increases with depth into the atmosphere, in agreement with radiative climate models. Seasonal hemispheric contrasts are perturbed at smaller scales by atmospheric circulation, such as belt/zone dynamics, the equatorial oscillations and the polar vortices. Temperature asymmetries are largest in the middle stratosphere and become insignificant near the radiative-convective boundary. Cassini has also measured southern-summertime asymmetries in atmospheric composition, including ammonia (the key species forming the topmost clouds), phosphine and para-hydrogen (both disequilibrium species) in the upper troposphere; and hydrocarbons deriving from the UV photolysis of methane in the stratosphere (principally ethane and acetylene). These chemical asymmetries are now altering in subtle ways due to (i) the changing chemical efficiencies with temperature and insolation and (ii) vertical motions associated with large-scale overturning in response to the seasonal temperature contrasts. Similarly, hemispheric contrasts in tropospheric aerosol opacity and coloration that were identified during the earliest phases of Cassini’s exploration have now reversed, suggesting an intricate link between the clouds and the temperatures. Finally, comparisons of observations between Voyager and Cassini (both observing in early northern spring, one Saturn year apart) show tantalizing suggestions of non-seasonal variability. Disentangling the competing effects of radiative balance, chemistry and dynamics in shaping the seasonal evolution of Saturn’s temperatures, clouds and composition remains the key challenge for the next generation of observations and numerical simulations.
This paper examines how state and non-state actors govern through pursuing speculative conservation among resource-dependent people who must renegotiate altered livelihoods amidst extractivism in ruptured landscapes. As donor aid declines and changes form, bilaterals, state agencies, and civil society now pursue advocacy in overlapping spaces of intensifying extractivism and speculative governance in the ruptured frontiers of Southeast Asia. In these spaces, bilaterals and non-governmental organisations (NGOs) struggle to work with upland farmers who negotiate the contrasting expectations of the abstract, speculative nature of conservation initiatives and the lucrative nature of extractive labour in the face of dramatic transformations of agrarian livelihoods and landscapes. Through a case study of the Philippine uplands, we demonstrate that as speculative conservation unfolds and manifests within and beyond these landscapes, it endeavours to revalue nature monetarily in ways that help reorganise labour and capital in an effort to overcome the exhaustion of capital wrought by rupture. We propose that during moments of rupture speculative conservation coproduces value from ruin by renewing and preserving capital flows.
A photoelectric radial velocity spectrometer has been in operation for several years at the coudé focus of the 1.2m telescope of the Dominion Astrophysical Observatory (DAO). The design of this instrument has been described by Fletcher et. al. (1982) and by McClure et al. (1984). These papers discuss the similarities and differences between this spectrometer and others of its type such as that constructed by Griffin and Gunn (1974) at Palomar. The spectrum mask in the present instrument consists of more than 700 transparent slots on an opaque background, representing the spectrum of a K giant star, plus a few slots to coincide with the argon lines in a cadmium-argon discharge tube for use in obtaining comparison arc velocities. By progressively tilting the slots an appropriate amount along the mask and scanning by moving the mask relative to the stellar spectrum at 45° to the dispersion it is possible to retain a spectral match at non-zero velocities. The masks are produced using a standard measuring engine modified with stepping motors controlled by a computer to position and tilt the slots. Since guiding errors are our major source of error we hope to make a significant improvement in this area in the following manner. By inserting an image rotating prism behind the slit a 180° rotation of the slit will occur when the prism is rotated. Although this has not yet been tested, it is hoped that by making this rotation every few scans the effects of guiding errors due to uneven illumination of the slit and collimator will be vastly reduced.
We question whether the increasingly popular, radical idea of turning half the Earth into a network of protected areas is either feasible or just. We argue that this Half-Earth plan would have widespread negative consequences for human populations and would not meet its conservation objectives. It offers no agenda for managing biodiversity within a human half of Earth. We call instead for alternative radical action that is both more effective and more equitable, focused directly on the main drivers of biodiversity loss by shifting the global economy from its current foundation in growth while simultaneously redressing inequality.
We have used the Dominion Astrophysical Observatory radial velocity spectrometer on the 3.6m Canada-France-Hawaii telescope to obtain radial velocities, accurate to ~0.8 km/s, for ~20 stars in each of nine globular clusters. The stars are generally within three core radii of the cluster center. The cluster names and metallicities (the latter are averages of values in Zinn and West (1984), Pilachowski (1984), and Webbink (1985)) are given in Table I. This sample includes two clusters with cusps in their surface brightness profiles: NGC 6624 and 6681.
A photoelectric radial-velocity spectrometer has been in use at the coudé focus of the 1.2m DAO telescope for several years. New improvements, resulting in a lowering of background noise, have allowed observations of stars significantly fainter than previously possible. Recent observations with the instrument at the coudé focus of the CFH telescope in Hawaii have shown that velocity measurements to better than 1 km s−1 accuracy are possible at 19th B magnitude. Various observing programs being carried out at DAO and CFHT are discussed.
This chapter shares details about the design and development of the Virtual Dental Implant Trainer (VDIT) learning game created for the Medical College of Georgia. The design and development team introduces the program by sharing the instructional goals of the learning game, basic design concepts, and development constraints. The chapter then highlights successes and discusses issues the team encountered during the design and development of the VDIT learning game. The emphasis is on sharing our experiences to help future organizations interested in creating or procuring learning game products learn from our example. Despite the issues, the team was able to minimize their impact and happily report that the game has been successfully created, tested, and delivered to the Medical College of Georgia for use in the affiliated dental school programs. The chapter closes with actionable recommendations for learning game design teams to help ensure delivery of successful game products.
The purpose of the Virtual Dental Implant Trainer (VDIT) project was to create a game-based simulation training tool to allow students to practice dental implant decision making during their free time. Nobel Biocare, a globally recognized maker of dental implant tools and hardware, through its partnership with the Medical College of Georgia (MCG), commissioned our team to design VDIT as a downloadable or CD-driven software package that could be distributed to medical students through its network of accredited schools and businesses.
The Hospital Anxiety and Depression Scale (HADS) has established use with older adult populations in New Zealand but few studies have evaluated its psychometric properties. Research with the psychometric properties of the HADS in elderly populations has primarily used correlational methods that do not allow for the effects of measurement error to be observed. The hypothesized tripartite model of anxiety and depression within the HADS was evaluated using confirmatory factor analysis (CFA) methods.
Overall, 203 community-dwelling older adults who were recruited from older adult community groups completed the HADS. Competing two- and three-factor structures were trialled using CFA.
A three-factor model indicated a lack of differentiation between factors and poor clinical utility and was rejected in favor of a two-factor model. Significant correlations were observed between the anxiety and depression factors on the two-factor model, but it was considered to have validity for older adult samples. Good internal consistency was found for the HADS.
A two-factor model of the HADS was favored due to the lack of differentiation between factors on the three-factor model, and the higher clinical utility of a two-factor solution. The validity of the HADS may be limited by over-diagnosing anxiety in non-clinical populations. It is recommended that the HADS be used to measure change over time through treatment and not be used as a diagnostic tool until future research establishes appropriate norms and cut-offs.
As archaeologists, we seek to understand variation and change in past human societies. This goal necessitates a comparative approach, and comparisons justify the broad cross-cultural and diachronic scope of our work. Without comparisons we sink into the culture-bound theorizing against which anthropology and archaeology have long sought to broaden social science research. By undertaking comparisons that incorporate long-term social variability, archaeologists not only improve our understanding of the past, but also open the door to meaningful transdisciplinary research. Archaeologists have unique and comprehensive data sets whose analysis can contribute to dialogues surrounding contemporary issues and the myriad challenges of our era.
In the past two decades, the pendulum seems to have swung away from comparative research in archaeology. Many archaeologists focus on detailed contextual descriptions of individual cases, and only a few have dedicated themselves to explicit comparative work. Yet in that same time span, fieldwork has expanded tremendously throughout the world, leading to an explosion of well-documented diachronic data on sites and regions. We now have substantial detail on the variation inherent in phenomena such as cultural assemblages, settlement patterns, and economic activity. New methods, from dating techniques to digital data processing, promote comparative analysis and greatly advance our understanding of human societies and change. The time is ripe for a renewed commitment to comparative research in archaeology.
Subcortical hyperintensities (SH) on neuroimaging are a prominent feature of vascular dementia (VaD) and SH severity correlates with cognitive impairment in this population. Previous studies demonstrated that SH burden accounts for a degree of the cognitive burden among VaD patients, although it remains unclear if individual factors such as cognitive reserve influence cognitive status in VaD. To address this issue, we examined 36 individuals diagnosed with probable VaD (age = 77.56; education = 12). All individuals underwent MMSE evaluations and MRI brain scans. We predicted that individuals with higher educational attainment would exhibit less cognitive difficulty despite similar levels of SH volume, compared to individuals with less educational attainment. A regression analysis revealed that greater SH volume was associated with lower scores on the MMSE. Additionally, education moderated the relationship between SH volume and MMSE score, demonstrating that individuals with higher education had higher scores on the MMSE despite similar degrees of SH burden. These results suggest that educational attainment buffers the deleterious effects of SH burden on cognitive status among VaD patients. (JINS, 2011, 17, 531–536)
Epitaxial GaAs layers have been grown on Ge-coated Si substrates. Deposition of epitaxial Ge was performed by electron beam evaporation onto a <100> Si substrate. GaAs was then deposited by organometallic vapor-phase epitaxy. Films grown over large areas (∼1 cm2) and by selective epitaxy in stripe patterns (∼50 μm wide) have been evaluated by a number of techniques to determine structural and electrical properties. In addition, we report what we believe to be the first LEDs fabricated in GaAs/Ge/Si heterostructures.
A technique for making rapidly-scanned, high-spatial resolution measurements of minority-carrier diffusion length is applied to the characterization of polycrystalline GaAs. Measurements on a large-grained n-type epitaxial layer show gradual variations of hole diffusion length from 0.1µm to l.lµm across the wafer as well as occasional small step changes at grain boundaries. By trading resolution for speed, the technique would be well suited to the nondestructive evaluation of large-area epitaxial layers.
The science of extra-solar planets is one of the most rapidly changing areas of astrophysics and since 1995 the number of planets known has increased by almost two orders of magnitude. A combination of ground-based surveys and dedicated space missions has resulted in 560-plus planets being detected, and over 1200 that await confirmation. NASA's Kepler mission has opened up the possibility of discovering Earth-like planets in the habitable zone around some of the 100,000 stars it is surveying during its 3 to 4-year lifetime. The new ESA's Gaia mission is expected to discover thousands of new planets around stars within 200 parsecs of the Sun. The key challenge now is moving on from discovery, important though that remains, to characterisation: what are these planets actually like, and why are they as they are?
In the past ten years, we have learned how to obtain the first spectra of exoplanets using transit transmission and emission spectroscopy. With the high stability of Spitzer, Hubble, and large ground-based telescopes the spectra of bright close-in massive planets can be obtained and species like water vapour, methane, carbon monoxide and dioxide have been detected. With transit science came the first tangible remote sensing of these planetary bodies and so one can start to extrapolate from what has been learnt from Solar System probes to what one might plan to learn about their faraway siblings. As we learn more about the atmospheres, surfaces and near-surfaces of these remote bodies, we will begin to build up a clearer picture of their construction, history and suitability for life.
The Exoplanet Characterisation Observatory, EChO, will be the first dedicated mission to investigate the physics and chemistry of Exoplanetary Atmospheres. By characterising spectroscopically more bodies in different environments we will take detailed planetology out of the Solar System and into the Galaxy as a whole.
EChO has now been selected by the European Space Agency to be assessed as one of four M3 mission candidates.
Background: It is well known that the global population is aging and that those over the age of 80 are the fastest growing part of this expansion. Also known is that prevalence of hypertension and cognitive decline both increase with increasing age.
Method: The Hypertension in the Very Elderly Trial (HYVET) was a double blind placebo-controlled trial of antihypertensive treatment (indapamide SR 1.5 mg ± perindopril 2–4 mg) and recruited only those hypertensives who were aged 80 or over and were without a diagnosis of dementia at baseline. Systolic blood pressure had to be in the range 160–199 mmHg and diastolic pressure <110 mmHg. Cognitive function was assessed at baseline using the Mini-mental State Examination prior to randomization into the trial. Also collected at baseline was information relating to sociodemographic, clinical, cardiovascular and biochemical factors which may impact upon cognitive function. This paper reports on the baseline cognitive function data from the HYVET trial and its relationship to these factors.
Results: The mean age of the 3763 HYVET participants who had full cognitive function data at baseline was 83.6 years; 60 percent were female. The median MMSE score at baseline was 26 and, in multivariate analyses, higher at younger age, with male gender, higher educational level, having higher creatinine, higher total cholesterol and lower high-density lipoprotein cholesterol.
Conclusions: This is the first such study to examine a large number of very elderly hypertensives and it shows some similar patterns to those seen in younger elderly groups.