We use cookies to distinguish you from other users and to provide you with a better experience on our websites. Close this message to accept cookies or find out how to manage your cookie settings.
To save content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about saving content to .
To save content items to your Kindle, first ensure no-reply@cambridge.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
We demonstrate a low-cost radio telescope using a 2.4-m satellite dish, an inexpensive printer circuit board (PCB)-based dual-pole antenna and commodity-off-the-shelf components. Open-source, radio acquisition and professional pulsar processing tools are used to successfully monitor on a daily basis the Southern Hemisphere pulsar J0835−4510 (the Vela pulsar) at 820 MHz as it transits the meridian. The system successfully detected a ‘glitch’ in the Vela pulsar in real-time at Woodchester Observatory in South Australia. Woodchester represents a good balance of bandwidth, observation time, and cost to achieve scientifically interesting results on pulsar timing for amateur radio astronomy and/or STEM outreach projects.
The ongoing deceleration of Whillans Ice Stream, West Antarctica, provides an opportunity to investigate the co-evolution of ice-shelf pinning points and ice-stream flux variability. Here, we construct and analyze a 20-year multi-mission satellite altimetry record of dynamic ice surface-elevation change (dh/dt) in the grounded region encompassing lower Whillans Ice Stream and Crary Ice Rise, a major pinning point of Ross Ice Shelf. We developed a new method for generating multi-mission time series that reduces spatial bias and implemented this method with altimetry data from the Ice, Cloud, and land Elevation Satellite (ICESat; 2003–09), CryoSat-2 (2010–present), and ICESat-2 (2018–present) altimetry missions. We then used the dh/dt time series to identify persistent patterns of surface-elevation change and evaluate regional mass balance. Our results suggest a persistent anomalous reduction in ice thickness and effective backstress in the peninsula connecting Whillans Ice Plain to Crary Ice Rise. The multi-decadal observational record of pinning-point mass redistribution and grounding zone retreat presented in this study highlights the on-going reorganization of the southern Ross Ice Shelf embayment buttressing regime in response to ice-stream deceleration.
Recent estimates of global salt marsh area sit at 5.5 million hectares (Mcowen et al. 2017). Conservatively, this translates to $1 trillion of ecosystem services per annum, potentially as much as $5 trillion (De Groot et al. 2012, Mehvar et al. 2018), equivalent to the entire US federal budget for 2019. There can be little debate as to the value of salt marshes, both in terms of the ecosystem services they provide and the key part they play in helping us understand past climate and sea level trends. This chapter summarizes the preceding work and draws together some key observations and notable knowledge gaps highlighted in the previous chapters. We provide a focus on the expected response of salt marshes to the stresses created by a changing climate.
Soldier operational performance is determined by their fitness, nutritional status, quality of rest/recovery, and remaining injury/illness free. Understanding large fluctuations in nutritional status during operations is critical to safeguarding health and well-being. There are limited data world-wide describing the effect of extreme climate change on nutrient profiles. This study investigated the effect of hot-dry deployments on vitamin D status (assessed from 25-hydroxyvitamin D (25(OH)D) concentration) of young, male, military volunteers. Two data sets are presented (pilot study, n 37; main study, n 98), examining serum 25(OH)D concentrations before and during 6-month summer operational deployments to Afghanistan (March to October/November). Body mass, percentage of body fat, dietary intake and serum 25(OH)D concentrations were measured. In addition, parathyroid hormone (PTH), adjusted Ca and albumin concentrations were measured in the main study to better understand 25(OH)D fluctuations. Body mass and fat mass (FM) losses were greater for early (pre- to mid-) deployment compared with late (mid- to post-) deployment (P<0·05). Dietary intake was well-maintained despite high rates of energy expenditure. A pronounced increase in 25(OH)D was observed between pre- (March) and mid-deployment (June) (pilot study: 51 (sd 20) v. 212 (sd 85) nmol/l, P<0·05; main study: 55 (sd 22) v. 167 (sd 71) nmol/l, P<0·05) and remained elevated post-deployment (October/November). In contrast, PTH was highest pre-deployment, decreasing thereafter (main study: 4·45 (sd 2·20) v. 3·79 (sd 1·50) pmol/l, P<0·05). The typical seasonal cycling of vitamin D appeared exaggerated in this active male population undertaking an arduous summer deployment. Further research is warranted, where such large seasonal vitamin D fluctuations may be detrimental to bone health in the longer-term.
This article shows how funding research on Alzheimer’s disease became a priority for the British Medical Research Council (MRC) in the late 1970s and 1980s, thanks to work that isolated new pathological and biochemical markers and showed that the disease affected a significant proportion of the elderly population. In contrast to histories that focus on the emergence of new and competing theories of disease causation in this period, I argue that concerns over the use of different assessment methods ensured the MRC’s immediate priority was standardising the ways in which researchers identified and recorded symptoms of Alzheimer’s disease in potential research subjects. I detail how the rationale behind the development of standard assessment guidelines was less about arriving at a firm diagnosis and more about facilitating research by generating data that could be easily compared across the disciplines and sites that constitute modern biomedicine. Drawing on criticism of specific tests in the MRC’s guidelines, which some psychiatrists argued were ‘middle class biased’, I also show that debates over standardisation did not simply reflect concerns specific to the fields or areas of research that the MRC sought to govern. Questions about the validity of standard assessment guidelines for Alzheimer’s disease embodied broader concerns about education and social class, which ensured that distinguishing normal from pathological in old age remained a contested and historically contingent process.
This book presents a wide range of new research on many aspects of naval strategy in the early modern and modern periods. Among the themes covered are the problems of naval manpower, the nature of naval leadership and naval officers, intelligence, naval training and education, and strategic thinking and planning. The book is notable for giving extensive consideration to navies other than those ofBritain, its empire and the United States. It explores a number of fascinating subjects including how financial difficulties frustrated the attempts by Louis XIV's ministers to build a strong navy; how the absence of centralised power in the Dutch Republic had important consequences for Dutch naval power; how Hitler's relationship with his admirals severely affected German naval strategy during the Second World War; and many more besides. The book is a Festschrift in honour of John B. Hattendorf, for more than thirty years Ernest J. King Professor of Maritime History at the US Naval War College and an influential figure in naval affairs worldwide.
N.A.M. Rodger is Senior Research Fellow at All Souls College, Oxford.
J. Ross Dancy is Assistant Professor of Military History at Sam Houston State University.
Benjamin Darnell is a D.Phil. candidate at New College, Oxford.
Evan Wilson is Caird Senior Research Fellow at the National Maritime Museum, Greenwich.
Contributors: Tim Benbow, Peter John Brobst, Jaap R. Bruijn, Olivier Chaline, J. Ross Dancy, Benjamin Darnell, James Goldrick, Agustín Guimerá, Paul Kennedy, Keizo Kitagawa, Roger Knight, Andrew D. Lambert, George C. Peden, Carla Rahn Phillips, Werner Rahn, Paul M. Ramsey, Duncan Redford, N.A.M. Rodger, Jakob Seerup, Matthew S. Seligmann, Geoffrey Till, Evan Wilson
Some extragalactic supernovae, such as SN 1986J in NGC 891 (Rupen et al. 1987), are unusually strong radio sources. Their radio emission typically peaks a few years after the supernova explodes, and appears to arise from the interaction of the supernova shock with a dense stellar wind shed by the progenitor star. Since two radio-loud and possibly optically faint supernovae have recently been found serendipitously in nearby spiral galaxies, it is possible that such objects are common. If so, this would have important consequences for our understanding of both the chemical enrichment history of galaxies and the radio emission from starburst galaxies. Preliminary results from a survey of nearby spiral galaxies with the Molonglo Observatory Synthesis Telescope (MOST) allow us to make a first estimate of the radio supernova rate. A larger study now in progress will provide a much more sensitive measurement.
Understanding the nutritional demands on serving military personnel is critical to inform training schedules and dietary provision. Troops deployed to Afghanistan face austere living and working environments. Observations from the military and those reported in the British and US media indicated possible physical degradation of personnel deployed to Afghanistan. Therefore, the present study aimed to investigate the changes in body composition and nutritional status of military personnel deployed to Afghanistan and how these were related to physical fitness. In a cohort of British Royal Marines (n 249) deployed to Afghanistan for 6 months, body size and body composition were estimated from body mass, height, girth and skinfold measurements. Energy intake (EI) was estimated from food diaries and energy expenditure measured using the doubly labelled water method in a representative subgroup. Strength and aerobic fitness were assessed. The mean body mass of volunteers decreased over the first half of the deployment ( − 4·6 (sd 3·7) %), predominately reflecting fat loss. Body mass partially recovered (mean +2·2 (sd 2·9) %) between the mid- and post-deployment periods (P< 0·05). Daily EI (mean 10 590 (sd 3339) kJ) was significantly lower than the estimated daily energy expenditure (mean 15 167 (sd 1883) kJ) measured in a subgroup of volunteers. However, despite the body mass loss, aerobic fitness and strength were well maintained. Nutritional provision for British military personnel in Afghanistan appeared sufficient to maintain physical capability and micronutrient status, but providing appropriate nutrition in harsh operational environments must remain a priority.
The purpose of the present study was to determine the effects of short-term supplementation with the free acid form of β-hydroxy-β-methylbutyrate (HMB-FA) on indices of muscle damage, protein breakdown, recovery and hormone status following a high-volume resistance training session in trained athletes. A total of twenty resistance-trained males were recruited to participate in a high-volume resistance training session centred on full squats, bench presses and dead lifts. Subjects were randomly assigned to receive either 3 g/d of HMB-FA or a placebo. Immediately before the exercise session and 48 h post-exercise, serum creatine kinase (CK), urinary 3-methylhistadine (3-MH), testosterone, cortisol and perceived recovery status (PRS) scale measurements were taken. The results showed that CK increased to a greater extent in the placebo (329 %) than in the HMB-FA group (104 %) (P= 0·004, d= 1·6). There was also a significant change for PRS, which decreased to a greater extent in the placebo (9·1 (sem 0·4) to 4·6 (sem 0·5)) than in the HMB-FA group (9·1 (sem 0·3) to 6·3 (sem 0·3)) (P= 0·005, d= − 0·48). Muscle protein breakdown, measured by 3-MH analysis, numerically decreased with HMB-FA supplementation and approached significance (P= 0·08, d= 0·12). There were no acute changes in plasma total or free testosterone, cortisol or C-reactive protein. In conclusion, these results suggest that an HMB-FA supplement given to trained athletes before exercise can blunt increases in muscle damage and prevent declines in perceived readiness to train following a high-volume, muscle-damaging resistance-training session.
Shape memory polymers (SMPs) are increasingly being considered for use in minimally invasive medical devices. For safe deployment of implanted devices it is important to be able to precisely control the actuation temperature of the device. In this study we report the effect of varying monomer composition on the glass transitions/actuation temperatures (Tg) of novel low density shape memory foams. The foams were based on hexamethylenediisocyanate (HDI), triethanolamine (TEA) and tetrakis (2-hydroxyl propyl) ethylenediamine (HPED), and were produced via a combination of chemical and physical blowing process. The process for post-foaming cleaning was also varied. Foams were characterized by DSC, DMA, and for shape memory. No clear trends were observed for foam samples without cleaning, and this was attributed to process chemicals acting as plasticizers. In foams cleaned via washing and/or sonication, the Tg was observed to decrease for compositions that were higher in the TEA content. Also, no change in shape memory behavior was observed for varying compositions. This work demonstrates the ability to tailor actuation transition temperature while maintaining shape memory behavior for low density foams suitable for aneurysm treatment.