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Up to 30% of the current tidewater mass loss in Svalbard corresponds to frontal ablation through submarine melting and calving. We developed two-dimensional (2-D) glacier–line–plume and glacier–fjord circulation coupled models, both including subglacial discharge, submarine melting and iceberg calving, to simulate Hansbreen–Hansbukta system, SW Svalbard. We ran both models for 20 weeks, throughout April–August 2010, using different scenarios of subglacial discharge and crevasse water depth. Both models showed large seasonal variations of submarine melting in response to transient fjord temperatures and subglacial discharges. Subglacial discharge intensity and crevasse water depth influenced calving rates. Using the best-fit configuration for both parameters our two coupled models predicted observed front positions reasonably well (±10 m). Although the two models showed different melt-undercutting front shapes, which affected the net-stress fields near the glacier front, no significant effects on the simulated glacier front positions were found. Cumulative calving (91 and 94 m) and submarine melting (108 and 118 m) along the simulated period showed in both models (glacier–plume and glacier–fjord) a 1:1.2 ratio of linear frontal ablation between the two mechanisms. Overall, both models performed well on predicting observed front positions when best-fit subglacial discharges were imposed, the glacier–plume model being 50 times computationally faster.
We present a detailed overview of the cosmological surveys that we aim to carry out with Phase 1 of the Square Kilometre Array (SKA1) and the science that they will enable. We highlight three main surveys: a medium-deep continuum weak lensing and low-redshift spectroscopic HI galaxy survey over 5 000 deg2; a wide and deep continuum galaxy and HI intensity mapping (IM) survey over 20 000 deg2 from
$z = 0.35$
to 3; and a deep, high-redshift HI IM survey over 100 deg2 from
$z = 3$
to 6. Taken together, these surveys will achieve an array of important scientific goals: measuring the equation of state of dark energy out to
$z \sim 3$
with percent-level precision measurements of the cosmic expansion rate; constraining possible deviations from General Relativity on cosmological scales by measuring the growth rate of structure through multiple independent methods; mapping the structure of the Universe on the largest accessible scales, thus constraining fundamental properties such as isotropy, homogeneity, and non-Gaussianity; and measuring the HI density and bias out to
$z = 6$
. These surveys will also provide highly complementary clustering and weak lensing measurements that have independent systematic uncertainties to those of optical and near-infrared (NIR) surveys like Euclid, LSST, and WFIRST leading to a multitude of synergies that can improve constraints significantly beyond what optical or radio surveys can achieve on their own. This document, the 2018 Red Book, provides reference technical specifications, cosmological parameter forecasts, and an overview of relevant systematic effects for the three key surveys and will be regularly updated by the Cosmology Science Working Group in the run up to start of operations and the Key Science Programme of SKA1.
We determined ice velocities for the Academy of Sciences Ice Cap, Severnaya Zemlya, Russian Arctic, during November 2016–November 2017, by feature-tracking 54 pairs of Sentinel-1 synthetic-aperture radar images. Seasonal velocity variations with amplitudes up to 10% of the yearly-averaged velocity were observed. Shorter-term (<15 d) intra-annual velocity variations had average and maximum deviations from the annual mean of up to 16 and 32%, respectively. This indicates the errors that could be incurred if ice discharge values determined from a single pair of images were extrapolated to the whole year. Average ice discharge for 2016–2017 was 1.93 ± 0.12 Gt a−1. The difference from an estimate of ~ 1.4 Gt a−1 for 2003–2009 was attributed to the initiation of ice stream flow in Basin BC. The total geodetic mass balance over 2012–2016 was − 1.72 ± 0.67 Gt a−1 (− 0.31 ± 0.12 m w.e. a−1). The climatic mass balance was not significantly different from zero, at 0.21 ± 0.68 Gt a−1 (0.04 ± 0.12 m w.e. a−1), and has remained near zero at decadal-scale for the last four decades. Therefore, the total mass balance has been controlled largely by variations in ice discharge, whose long-term changes do not appear to have responded to environmental changes but to the intrinsic characteristics of the ice cap governing tidewater glacier dynamics.
To study subglacial hydrological condition and its influence on the glacier dynamics, we drilled Johnsons Glacier on Livingston Island in the Antarctic Peninsula region. Subglacial water pressure was recorded in boreholes at two locations over 2 years, accompanied by high-frequency ice-speed measurements during two summer melt seasons. Water pressure showed two different regimes, namely high frequency and large amplitude variations during the melt season (January–April) and small fluctuations near the overburden pressure the rest of the year. Speed-up events were observed several times in each summer measurement period. Ice motion during these events substantially contributed to total glacier motion, for example, fast ice flow over 1 week accounted for ~70% of the total displacement over a 25-day long measurement period. We did not find a clear relationship between subglacial water pressure and ice speed. This was probably because subglacial hydraulic conditions were spatially inhomogeneous and thus our borehole data did not always represent a large-scale subglacial condition. Ice temperature measurements in the boreholes confirmed the existence of a cold ice layer near the glacier surface. Our data provide a basis to better understand the dynamic and hydrological conditions of relatively unstudied glaciers in the Antarctic Peninsula region.
Healthy lifestyle habits are the cornerstone in the management of familial hypercholesterolaemia (FH). Nevertheless, dietary studies on FH-affected populations are scarce. The present study analyses dietary habits, adherence to a Mediterranean diet pattern and physical activity in an adult population with FH and compares them with their non-affected relatives.
Data came from SAFEHEART, a nationwide study in Spain.
Individuals (n 3714) aged ≥18 years with a genetic diagnosis of FH (n2736) and their non-affected relatives (n 978). Food consumption was evaluated using a validated FFQ.
Total energy intake was lower in FH patients v. non-affected relatives (P<0·005). Percentage of energy from fats was also lower in the FH population (35 % in men, 36 % in women) v. those non-affected (38 % in both sexes, P<0·005), due to the lower consumption of saturated fats (12·1 % in FH patients, 13·2 % in non-affected, P<0·005). Consumption of sugars was lower in FH patients v. non-affected relatives (P<0·05). Consumption of vegetables, fish and skimmed milk was higher in the FH population (P<0·005). Patients with FH showed greater adherence to a Mediterranean diet pattern v. non-affected relatives (P<0·005). Active smoking was lower and moderate physical activity was higher in people with FH, especially women (P<0·005).
Adult patients with FH report healthier lifestyles than their non-affected family members. They eat a healthier diet, perform more physical activity and smoke less. However, this patient group’s consumption of saturated fats and sugars still exceeds guidelines.
We analyse the various error sources in the estimation of ice discharge through flux gates, distinguishing the cases with ice-thickness data available for glacier cross-sections or only along the centreline. For the latter, we analyse the performance of three U-shaped cross-sectional approaches. We apply this methodology to glaciers of the Canadian High Arctic. The velocity field is the main error source for small and medium-size glaciers (discharge <100 Mt a−1) with low velocities (<100 m a−1), while for large glaciers (discharge >100 Mt a−1) with high velocities (>100 m a−1) the error in cross-sectional area dominates. Thinning/thickening between ice-thickness and velocity measurements should be considered, as it implies systematic errors up to 8% in our study. The U-shaped parabolic approach, which allows for an adjusted estimation when the ice-thickness measurement point is displaced from the glacier centreline, performs best, with small bias and admissible standard error. We observe an increase of ice discharge from the main glaciers (Trinity and Wykeham) of the Prince of Wales Icefield from 2015 to 2016, by 5 and 20%, respectively, followed by a decrease in 2017, by 10 and 15%, respectively. Belcher Glacier, of the Devon Ice Cap, maintains similar discharges during 2015–17.
To compare the epidemiology, clinical characteristics, and mortality of patients with bloodstream infections (BSI) caused by extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (ESBL-EC) versus ESBL-producing Klebsiella pneumoniae (ESBL-KP) and to examine the differences in clinical characteristics and outcome between BSIs caused by isolates with CTX-M versus other ESBL genotypes
As part of the INCREMENT project, 33 tertiary hospitals in 12 countries retrospectively collected data on adult patients diagnosed with ESBL-EC BSI or ESBL-KP BSI between 2004 and 2013. Risk factors for ESBL-EC versus ESBL-KP BSI and for 30-day mortality were examined by bivariate analysis followed by multivariable logistic regression.
The study included 909 patients: 687 with ESBL-EC BSI and 222 with ESBL-KP BSI. ESBL genotype by polymerase chain reaction amplification of 286 isolates was available. ESBL-KP BSI was associated with intensive care unit admission, cardiovascular and neurological comorbidities, length of stay to bacteremia >14 days from admission, and a nonurinary source. Overall, 30-day mortality was significantly higher in patients with ESBL-KP BSI than ESBL-EC BSI (33.7% vs 17.4%; odds ratio, 1.64; P=.016). CTX-M was the most prevalent ESBL subtype identified (218 of 286 polymerase chain reaction-tested isolates, 76%). No differences in clinical characteristics or in mortality between CTX-M and non–CTX-M ESBLs were detected.
Clinical characteristics and risk of mortality differ significantly between ESBL-EC and ESBL-KP BSI. Therefore, all ESBL-producing Enterobacteriaceae should not be considered a homogeneous group. No differences in outcomes between genotypes were detected.
The synthesis and antiprotozoal activity of some simple dialkyl pyrazole-3,5-dicarboxylates (compounds 2–6) and their sodium salts (pyrazolates) (compounds 7–9) against Trypanosoma cruzi, Leishmania infantum and Leishmania braziliensis are reported. In most cases the studied compounds showed, especially against the clinically significant amastigote forms, in vitro activities higher than those of the reference drugs (benznidazole for T. cruzi and glucantime for Leishmania spp.); furthermore, the low non-specific cytotoxicities against Vero cells and macrophages shown by these compounds led to good selectivity indexes, which are 8–72 times higher for T. cruzi amastigotes and 15–113 times higher for Leishmania spp. amastigotes than those of the respective reference drugs. The high efficiency of diethyl ester 3 and its sodium salt 8 against the mentioned protozoa was confirmed by further in vitro assays on infection rates and by an additional in vivo study in a murine model of acute and chronic Chagas disease. The inhibitory capacity of compounds 3 and 8 on the essential iron superoxide dismutase of the aforementioned parasites may be related to the observed anti-trypanosomatid activity. The low acute toxicity of compounds 3 and 8 in mice is also reported in this article.
This study examines the short-run response of daily stock prices in the Spanish market to the announcements of inflation news at a sector level at the moments when the Spanish authorities announced the IPC (consumer price index) during the period 1995–2004. The study also incorporates two novel explanatory variables: core inflation and ‘non-core’ inflation rate components on the one hand, and the spread between the Spanish and European inflation rates (harmonized) on the other hand. It is concluded that the ‘non-core’ component of the inflation rate, which is more volatile, has negative effects on some sector returns; additionally, in drawing too far apart from the European inflation rate, the Spanish inflation rate negatively affects sector returns, such as in the ‘Consumer Goods’ sector, which is subject to strong foreign competition. In the long-term analysis, the lagged core inflation (structural component) negatively affects sector returns.
In this paper we investigate different methods that may be used to compare coherent systems having heterogeneous components. We consider both the case of systems with independent components and the case of systems with dependent components. In the first case, the comparisons are based on the new concept of the survival signature due to Coolen and Coolen-Maturi (2012) which extends the well-known concept of system signatures to the case of components with lifetimes that need not be independent and identically distributed. In the second case, the comparisons are based on the concept of distortion functions. A graphical procedure (called an RR-plot) is proposed as an alternative to the analytical methods when there are two types of components.
The ommastrephid squid, Illex coindetii, is one of the most abundant cephalopods in the Mediterranean Sea and an important predator in the ecosystem. In the present study, we examined the diet habits of I. coindetii in the north-western Mediterranean Sea by combining two complementary approaches: stomach content and stable isotopic analyses. Specifically, we examined whether the diet differed between sizes and seasons. Stomach content results indicated that the diet of I. coindetii was composed of 35 prey items including four major groups; namely the crustaceans Pasiphaea sivado, Amphipods, squid of the Order Teuthida, and pelagic and mesopelagic fish. Differences were found among different ontogenetic sizes: juvenile individuals fed mainly on crustaceans (%IRI = 77.59), whereas adult individuals fed on a wider range of prey items, including the shrimp P. sivado (%IRI = 33.21), the amphipod Anchylomera blossevillei (%IRI = 0.91), the decapod Plesionika sp. (%IRI = 0.19), the carangid Trachurus trachurus (%IRI = 0.34) and some Myctophids species (%IRI = 0.21). Differences were also found between seasons in the year. In winter, crustaceans were the main prey items, whereas in summer the diversity of prey was higher, including fish, crustaceans and molluscs. Similar to the stomach contents, stable isotopic results indicated differences among sizes. δ15N values were higher in adult squids than in juveniles because they fed on prey at higher trophic levels. In conclusion, this study indicates that feeding habits of I. coindetii vary seasonally and ontogenetically. These feeding variations may be associated with trophic competence scenarios based on size, and also with the availability and abundance of prey throughout the year.
The signature of a system is defined as the vector whose ith element is the probability that the system fails concurrently with the ith component failure. The signature vector is known to be a distribution-free measure and a representation of the system's survival function has been developed in terms of the system's signature. The present work is devoted to the study of the joint distribution of lifetimes of pairs of systems with shared components. Here, a new distribution-free measure, the ‘joint bivariate signature’, of a pair of systems with shared components is defined, and a new representation theorem for the joint survival function of the system lifetimes is established. The theorem is shown to facilitate the study of the dependence between systems and the comparative performance of two pairs of such systems.
We present an update of the ‘key points’ from the Antarctic Climate Change and the Environment (ACCE) report that was published by the Scientific Committee on Antarctic Research (SCAR) in 2009. We summarise subsequent advances in knowledge concerning how the climates of the Antarctic and Southern Ocean have changed in the past, how they might change in the future, and examine the associated impacts on the marine and terrestrial biota. We also incorporate relevant material presented by SCAR to the Antarctic Treaty Consultative Meetings, and make use of emerging results that will form part of the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report.
A new 10 year surface mass balance (SMB) record of Hurd and Johnsons Glaciers, Livingston Island, Antarctica, is presented and compared with earlier estimates on the basis of local and regional meteorological conditions and trends. Since Johnsons is a tidewater glacier, we also include a calving flux calculation to estimate its total mass balance. The average annual SMB over the 10 year observation period 2002–11 is −0.15 ± 0.10 m w.e. for Hurd Glacier and 0.05 ± 0.10 m w.e. for Johnsons Glacier. Adding the calving losses to the latter results in a total mass balance of −0.09 ± 0.10 m w.e. There has been a deceleration of the mass losses of these glaciers from 1957–2000 to 2002–11, which have nearly halved for both glaciers. We attribute this decrease in the mass losses to a combination of increased accumulation in the region and decreased melt. The increased accumulation is attributed to larger precipitation associated with the recent deepening of the circumpolar pressure trough, while the melt decrease is associated with lower summer surface temperatures during the past decade.
Signature-based representations of the reliability functions of coherent systems with independent and identically distributed component lifetimes have proven very useful in studying the ageing characteristics of such systems and in comparing the performance of different systems under varied criteria. In this paper we consider extensions of these results to systems with heterogeneous components. New representation theorems are established for both the case of components with independent lifetimes and the case of component lifetimes under specific forms of dependence. These representations may be used to compare the performance of systems with homogeneous and heterogeneous components.
System signatures are useful tools in the study and comparison of coherent systems. In this paper, we define and study a similar concept, called the joint signature, for two coherent systems which share some components. Under an independent and identically distributed assumption on component lifetimes, a pseudo-mixture representation based on this joint signature is obtained for the joint distribution of the lifetimes of both systems. Sufficient conditions are given based on the respective joint signatures of two pairs of systems, each with shared components, to ensure various forms of bivariate stochastic orderings between the joint lifetimes of the two pairs of systems.
In May–June 2009, thirteen adult individuals of the round stingray Urobatis halleri, with total lengths between 264 and 353 mm, were captured using various fishing gear at La Paz Bay, Baja California Sur, Mexico. The specimens were notable for the presence of ocular malformations, and uniform dark mucus that completely covered the dorsal surface and some portions of the ventral region. These malformations may be a result of one or several factors, including parasitic infection, tumours, or water pollution.
Calving from tidewater glaciers and ice shelves accounts for around half the mass loss from both polar ice sheets, yet the process is not well represented in prognostic models of ice dynamics. Benn and others proposed a calving criterion appropriate for both grounded and floating glacier tongues or ice shelves, based on the penetration depth of transverse crevasses near the calving front, computed using Nye’s formula. The criterion is readily incorporated into glacier and ice-sheet models, but has not been fully validated with observations. We apply a three-dimensional extension of Benn and others’ criterion, incorporated into a full-Stokes model of glacier dynamics, to estimate the current position of the calving front of Johnsons Glacier, Antarctica. We find that two improvements to the original model are necessary to accurately reproduce the observed calving front: (1) computation of the tensile deviatoric stress opening the crevasse using the full-stress solution and (2) consideration of such a tensile stress as a function of depth. Our modelling results also suggest that Johnsons Glacier has a polythermal structure, rather than the temperate structure suggested by earlier studies.