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"Daly, R."
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A concise history of modern India
\"A Concise History of Modern India, by Barbara D. Metcalf and Thomas R. Metcalf, has become a classic in the field since it was first published in 2001. As a fresh interpretation of Indian history from the Mughals to the present, it has informed students across the world. In the third edition of the book, a final chapter charts the dramatic developments of the last twenty years, from 1990 through the Congress electoral victory of 2009, to the rise of the Indian high-tech industry in a country still troubled by poverty and political unrest. The narrative focuses on the fundamentally political theme of the imaginative and institutional structures that have successively sustained and transformed India, first under British colonial rule and then, after 1947, as an independent country. Woven into the larger political narrative is an account of India's social and economic development, and its rich cultural life. Throughout, the authors argue that despite a powerful historiographical tradition to the contrary, no enduring meaning can be given to categories such as 'caste', 'Hindu', 'Muslim', or even 'India'\"-- Provided by publisher.
Book
Low surface strength of the asteroid Bennu inferred from impact ejecta deposit
The surface strength of small rubble-pile asteroids, which are aggregates of unconsolidated material under microgravity, is poorly constrained but critical to understanding surface evolution and geologic history of the asteroid. Here we use images of an impact ejecta deposit and downslope avalanche adjacent to a 70-m-diameter impact crater on the rubble-pile asteroid (101955) Bennu to constrain the asteroid’s surface properties. We infer that the ejecta deposited near the crater must have been mobilized with velocities less than Bennu’s escape velocity (20 cm s
–1
); such low velocities can be explained only if the effective strength of the local surface is exceedingly low, nominally ≤2 Pa. This value is four orders of magnitude below strength values commonly used for asteroid surfaces, but it is consistent with recent estimates of internal strength of rubble-pile asteroids and with the surface strength of another rubble-pile asteroid, Ryugu. We find a downslope avalanche indicating a surface composed of material readily mobilized by impacts and that has probably been renewed multiple times since Bennu’s initial assembly. Compared with stronger surfaces, very weak surfaces imply (1) more retention of material because of the low ejecta velocities and (2) lower crater-based age estimates—although the heterogeneous structure of rubble piles complicates interpretation.
Observations of deposits associated with a crater on the rubble-pile asteroid Bennu indicate a surface with low strength that is readily reworked by impact processes.
Journal Article
Mapping the Acehnese past
Aceh has become best known in our times for its twin disasters - the worst earthquake and tsunami of modern times in December 2004, and a long-running separatist conflict that rent Indonesia for most of its independent history. Although this book emerged from the process of recovery from those traumas, it turns the spotlight on a more positive and neglected claim Aceh has on our attention, as the South east Asian maritime state that most successfully and creatively maintained its independent pace in the world until 1874. Like Burma, Siam and Vietnam, all better protected by geography, Aceh has its own story to tell of a unique culture struggling for suvival through the European colonial era.
Book
Associations between sedentary behaviour and body composition, muscle function and sarcopenia in community-dwelling older adults
Summary
While previous studies have reported detrimental associations of sedentary behaviours with cardiometabolic disorders and mortality, in this study, we report that higher levels of sitting time were associated with a greater risk of sarcopenia, with increased television (TV) viewing negatively associated with lean mass, independent of physical activity.
Introduction
Sedentary behaviour has been linked to cardiometabolic disorders and mortality, but little is known about its effects on musculoskeletal health and function. This study investigated the relationship between total sitting and TV viewing time on sarcopenia and its determinants (muscle mass, strength and function) in older adults.
Methods
This cross-sectional study included 162 community-dwelling men and women aged 60 to 86 years who had complete assessment of total body and regional lean mass (LM) and fat mass (dual-energy X-ray absorptiometry (DXA)), lower limb muscle strength, power and functional performance. Sarcopenia was defined as the lowest sex-specific quartile for relative appendicular LM plus muscle strength and/or gait speed. Total sitting and TV viewing time were self-reported using a validated questionnaire. A sitting fragmentation ratio, as an index of breaks in sitting time, was calculated as the number of sitting bouts divided by total sitting time.
Results
Greater overall sitting time was associated with an increased risk of sarcopenia; for each 1-h increment, the risk increased by 33 % [odds ratio 1.33 (95 % confidence interval (CI) 1.05, 1.68)], independent of physical activity and other lifestyle and confounding factors. TV viewing time was associated with lower total body and leg LM after adjusting for various confounders and fat mass. There were no associations between total sitting or TV viewing time or the fragmentation ratio with any other measure.
Conclusion
Higher levels of sedentary behaviour in older adults were associated with reduced muscle mass and an increased risk of sarcopenia in community-dwelling older adults, independent of physical activity.
Journal Article
Crater Population on Asteroid (101955) Bennu Indicates Impact Armouring and a Young Surface
The impactor-to-crater size scaling relationships that enable estimates of planetary surface ages rely on an accurate formulation of impactor–target physics. An armouring regime, specific to rubble-pile surfaces, has been proposed to occur when an impactor is comparable in diameter to a target surface particle (for example, a boulder). Armouring is proposed to reduce crater diameter, or prevent crater formation in the asteroid surface, at small crater diameters. Here, using measurements of 1,560 craters on the rubble-pile asteroid (101955) Bennu, we show that the boulder population controls a transition from crater formation to armouring at crater diameters ~2–3 m, below which crater formation in the bulk surface is increasingly rare. By combining estimates of impactor flux with the armouring scaling relationship, we find that Bennu’s crater retention age (surface age derived from crater abundance) spans from 1.6–2.2 Myr for craters less than a few meters to ~10–65 Myr for craters >100 m in diameter, reducing the maximum surface age by a factor of >15 relative to previous estimates. The range of crater retention ages, together with latitudinal variations in large-crater spatial density, indicate that ongoing resurfacing processes render the surface many times younger than the bulk asteroid.
Journal Article
The bearing capacity of asteroid (65803) Didymos estimated from boulder tracks
The bearing capacity - the ability of a surface to support applied loads - is an important parameter for understanding and predicting the response of a surface. Previous work has inferred the bearing capacity and trafficability of specific regions of the Moon using orbital imagery and measurements of the boulder tracks visible on its surface. Here, we estimate the bearing capacity of the surface of an asteroid for the first time using DART/DRACO images of suspected boulder tracks on the surface of asteroid (65803) Didymos. Given the extremely low surface gravity environment, special attention is paid to the underlying assumptions of the geotechnical approach. The detailed analysis of the boulder tracks indicates that the boulders move from high to low gravitational potential, and provides constraints on whether the boulders may have ended their surface motion by entering a ballistic phase. From the 9 tracks identified with sufficient resolution to estimate their dimensions, we find an average boulder track width and length of 8.9
±
1.5 m and 51.6
±
13.3 m, respectively. From the track widths, the mean bearing capacity of Didymos is estimated to be 70 N/m
2
, implying that every 1 m
2
of Didymos’ surface at the track location can support only ~70 N of force before experiencing general shear failure. This value is at least 3 orders of magnitude less than the bearing capacity of dry sand on Earth, or lunar regolith.
Bearing capacity, the ability of a surface to support applied loads, is a critical property in planetary exploration to understand a surface’s response to landing or roving. Here, the bearing capacity of the asteroid Didymos is estimated using DART images of suspected boulder tracks on its surface.
Journal Article
High-resolution synchrotron imaging shows that root hairs influence rhizosphere soil structure formation
In this paper, we provide direct evidence of the importance of root hairs on pore structure development at the root–soil interface during the early stage of crop establishment.
This was achieved by use of high-resolution (c. 5 μm) synchrotron radiation computed tomography (SRCT) to visualise both the structure of root hairs and the soil pore structure in plant–soil microcosms. Two contrasting genotypes of barley (Hordeum vulgare), with and without root hairs, were grown for 8d in microcosms packed with sandy loam soil at 1.2 g cm−3 dry bulk density. Root hairs were visualised within air-filled pore spaces, but not in the fine-textured soil regions.
We found that the genotype with root hairs significantly altered the porosity and connectivity of the detectable pore space (> 5 μm) in the rhizosphere, as compared with the no-hair mutants. Both genotypes showed decreasing pore space between 0.8 and 0.1mm from the root surface. Interestingly the root-hair-bearing genotype had a significantly greater soil pore volume-fraction at the root–soil interface.
Effects of pore structure on diffusion and permeability were estimated to be functionally insignificant under saturated conditions when simulated using image-based modelling.
Journal Article
Mechanical properties of rubble pile asteroids (Dimorphos, Itokawa, Ryugu, and Bennu) through surface boulder morphological analysis
Planetary defense efforts rely on estimates of the mechanical properties of asteroids, which are difficult to constrain accurately from Earth. The mechanical properties of asteroid material are also important in the interpretation of the Double Asteroid Redirection Test (DART) impact. Here we perform a detailed morphological analysis of the surface boulders on Dimorphos using images, the primary data set available from the DART mission. We estimate the bulk angle of internal friction of the boulders to be 32.7 ± 2. 5° from our measurements of the roundness of the 34 best-resolved boulders ranging in size from 1.67–6.64 m. The elongated nature of the boulders around the DART impact site implies that they were likely formed through impact processing. Finally, we find striking similarities in the morphology of the boulders on Dimorphos with those on other rubble pile asteroids (Itokawa, Ryugu and Bennu). This leads to very similar internal friction angles across the four bodies and suggests that a common formation mechanism has shaped the boulders. Our results provide key inputs for understanding the DART impact and for improving our knowledge about the physical properties, the formation and the evolution of both near-Earth rubble-pile and binary asteroids.
Planetary Defense efforts rely on estimates of asteroids’ mechanical properties, which are difficult to obtain accurately from Earth. Here, authors compare images from space missions to the rubble-pile asteroids Dimorphos, Itokawa, Ryugu, and Bennu and study such properties through boulders on their surface.
Journal Article
Acoustic telemetry reveals multi-seasonal spatiotemporal dynamics of a giant trevally Caranx ignobilis aggregation
Predictable fish aggregations of commercially valuable species are particularly susceptible to overexploitation. Giant trevally Caranx ignobilis are ecologically important top predatory fish targeted in both recreational and commercial fisheries; however, little is known about their aggregation dynamics or susceptibility to overexploitation. This study employed acoustic telemetry to investigate the temporal and spatial characteristics of one of the largest known aggregations of this species over a 3 yr period in a marine protected area in Mozambique, West Indian Ocean. Tagged fish were monitored for between 386 and 1176 d, during which they exhibited distinct aggregative periods in austral spring and summer. The detection frequency of fish at the aggregation site was significantly associated with rising mean sea temperatures and the full moon period. Whilst at the aggregation site, fish exhibited clear patterns of diel periodicity, with maximum hourly detections recorded during midday. All fish exhibited periods of absence from the aggregation site between summer seasons, in which time many of them ranged across an international border for distances of between 11 and 633 km before returning to aggregate at the same site in the following season. These results confirm that the studied giant trevally aggregation is temporally and spatially predictable, and consistent with a transient site-specific fish spawning aggregation. The spatiotemporal predictability of the aggregation highlights the need for the effective management of this transboundary population of giant trevally, for which this study has provided conservation management recommendations.
Journal Article
Design Heuristics in Engineering Concept Generation
Innovation in design depends on successful concept generation. The ideation stage of design is intended to produce multiple, varied concepts from which to develop and choose. Often, instruction on idea generation methods is not offered in engineering classes; however, when taught, it is commonly through techniques like brainstorming, which lacks specific ways to generate designs. Further, existing ideation strategies are not based on evidence from designers or rigorous testing through empirical studies. This study investigated how engineering students and practitioners generated ideas. We focused on how designers used product characteristics to define concepts, and how previous concepts were transformed into new solutions by modifying their characteristics. Our methodology is based on our previous work identifying Design Heuristics in engineering solutions, defined as cognitive prompts that facilitate exploration of multiple designs during concept generation. Think-aloud recordings and concept sketches were collected from 36 engineering students and practitioners (with varying levels of experience) as they generated ideas for a novel design task in a laboratory setting. These data, along with retrospective interviews, were analyzed for the ideation strategies evident in the participants' solutions. This study revealed evidence for over 60 strategies for concept generation during the ideation stage. Participants generated novel concepts and proposed concept modifications, and specific Design Heuristics were observed in their designs. The results suggest instruction on Design Heuristics can aid in effective idea generation. This protocol study of engineering designers provides a collection of heuristics observed in practice that offers new methods for students and practitioners to explore design spaces. The Design Heuristics identified in this and previous work can potentially be learned and then incorporated into the practice of engineering students and practitioners.
Journal Article