2,015 research outputs found
Subpixel-Scale Topography Retrieval of Mars Using Single-Image DTM Estimation and Super-Resolution Restoration
We propose using coupled deep learning based super-resolution restoration (SRR) and single-image digital terrain model (DTM) estimation (SDE) methods to produce subpixel-scale topography from single-view ESA Trace Gas Orbiter Colour and Stereo Surface Imaging System (CaSSIS) and NASA Mars Reconnaissance Orbiter High Resolution Imaging Science Experiment (HiRISE) images. We present qualitative and quantitative assessments of the resultant 2 m/pixel CaSSIS SRR DTM mosaic over the ESA and Roscosmos Rosalind Franklin ExoMars rover’s (RFEXM22) planned landing site at Oxia Planum. Quantitative evaluation shows SRR improves the effective resolution of the resultant CaSSIS DTM by a factor of 4 or more, while achieving a fairly good height accuracy measured by root mean squared error (1.876 m) and structural similarity (0.607), compared to the ultra-high-resolution HiRISE SRR DTMs at 12.5 cm/pixel. We make available, along with this paper, the resultant CaSSIS SRR image and SRR DTM mosaics, as well as HiRISE full-strip SRR images and SRR DTMs, to support landing site characterisation and future rover engineering for the RFEXM22
Are blackcaps sylvia atricapilla differential distance migrants by sex?
Aims: To investigate if male and female blackcaps show differences in the amplitude of migratory
movements.
Methods: The extent of movements of male and female British blackcaps were analysed using ringing recovery
records. Furthermore, through a literature review and the collection of original field data, the
sex-ratios of blackcap samples taken at several latitudes in Europe and Africa were compared.
Results: There were no differences between British male and female blackcaps in relation to wintering
latitude or distance moved during migration. Sex-ratios of blackcap samples were quite even across a wide
range of latitudes. However, there was a significantly larger proportion of females in samples of birds that
wintered in Africa.
Conclusions: Laboratory data and morphological studies have yielded inconclusive results in relation to
the question of whether or not European blackcaps are differential distance migrants. The results from the
present study suggest that British blackcaps are not differential distance migrants. Furthermore, there is,
at best, only a weak latitudinal segregation of the sexes of blackcaps wintering in Europe and Africa. The
slightly higher proportion of males in European samples, when compared to Africa, could result from a
differential behaviour of males and females in some blackcap populations, or simply result from differences
in the sex-ratios of blackcap populations breeding and wintering in different areas. An absence of
a pronounced latitudinal segregation in the size-monomorphic blackcap is interesting, and contrasts
with the pattern found in more sexually dimorphic species, such as the chiffchaff Phylloscopus collybita
or the robin Erithacus rubecula
Differential migration of chiffchaffs Phylloscopus collybita and P. ibericus in Europe and Africa
Differential migration is a widespread, but poorly understood, phenomenon in birds. In
this paper, we present the first detailed field study of differential migration in the Old
World warbler (Sylviidae) family. We studied two chiffchaff Phylloscopus [collybita ]
semispecies: the common chiffchaff P. [c. ] collybita and the Iberian chiffchaff P. [c. ]
ibericus. Using data collected at several latitudes in Europe and Africa, we present
convincing evidence for differential distance migration of sexes in chiffchaffs, with
females moving further than males. Interestingly, while there was a pronounced
gradient in the sex-ratios in Europe and North Africa (with an increasing proportion of
females with declining latitude), no clear pattern was found south of the Sahara, where
sex-ratios were more male-biased than predicted by a simple latitude model. This
suggests that, amongst the chiffchaffs wintering in West Africa, a large proportion is
composed by Iberian birds, and provides support to previous suggestions that Iberian
chiffchaffs are long distance migrants. Results from detailed studies in Senegal also
show that chiffchaffs display differential timing of spring migration, with males leaving
the winter quarters considerably earlier than females. The results are discussed in the
framework of the three main (non-mutually exclusive) hypotheses attempting to explain
the latitudinal segregation of the sexes. Given the relative failure of standard
comparative studies to discriminate between competing single-factor hypotheses to
explain differential migration, it is argued that the chiffchaff species complex might be
particularly suited to study this issue using a new approach suggested by Cristol et al.
(1999): detailed (further) comparisons between closely related species (such as the
common and the Iberian chiffchaffs) could help identifying the key factors to be
incorporated into optimality models that can predict relative distance of migration of
different sex or age classes
Habitat selection and specialisation of herring gulls during the non-breeding season
Understanding both the distribution and habitat use of populations through the annual cycle is vital to understanding how vulnerable species are to environmental change. However, distributions and habitat use can vary among individuals and populations, particularly in generalist species, with variation depending on external environmental factors, such as resource availability. Comprehensive information across multiple populations is important to guide spatial planning of protected areas and is increasingly available for breeding individuals, but it is still lacking for many species, particularly seabirds, during the non-breeding season, especially those with declining populations. We investigated within-species variation in migratory strategies, non-breeding habitat selection and habitat and spatial specialisation in a declining, opportunistic, generalist seabird, the European herring gull Larus argentatus, from multiple breeding colonies across northwest England and southwest Scotland using global positioning system (GPS) tracking during the non-breeding season of 2014/15. Although several individuals stayed within the area of the breeding colony, the majority of individuals migrated in a southerly direction and spent half of the annual cycle (on average 53%) away from the breeding area and kept moving through the non-breeding period. During non-breeding, herring gulls selected mainly marine intertidal, but also a range of anthropogenic terrestrial habitats. However, habitat selection differed between geographical regions, within a geographical region and among individuals. There was a generalist use of non-breeding habitats at the population level, but some habitat specialisation at the individual level that was repeatable through the non-breeding period despite individuals showing low spatial specialisation. The results highlight the importance of intertidal habitat and a mix of alternative foraging habitats in the wintering areas of herring gulls. The results also highlight that habitat selection in an opportunistic generalist can vary even between nearby regions and that appropriate conservation management plans may need to be tailored to regional differences in specific non-breeding areas
Haemoglobin C and S Role in Acquired Immunity against Plasmodium falciparum Malaria
A recently proposed mechanism of protection for haemoglobin C (HbC; β6Glu→Lys) links an abnormal display of PfEMP1, an antigen involved in malaria pathogenesis, on the surface of HbC infected erythrocytes together with the observation of reduced cytoadhesion of parasitized erythrocytes and impaired rosetting in vitro. We investigated the impact of this hypothesis on the development of acquired immunity against Plasmodium falciparum variant surface antigens (VSA) encoding PfEMP1 in HbC in comparison with HbA and HbS carriers of Burkina Faso. We measured: i) total IgG against a single VSA, A4U, and against a panel of VSA from severe malaria cases in human sera from urban and rural areas of Burkina Faso of different haemoglobin genotypes (CC, AC, AS, SC, SS); ii) total IgG against recombinant proteins of P. falciparum asexual sporozoite, blood stage antigens, and parasite schizont extract; iii) total IgG against tetanus toxoid. Results showed that the reported abnormal cell-surface display of PfEMP1 on HbC infected erythrocytes observed in vitro is not associated to lower anti- PfEMP1 response in vivo. Higher immune response against the VSA panel and malaria antigens were observed in all adaptive genotypes containing at least one allelic variant HbC or HbS in the low transmission urban area whereas no differences were detected in the high transmission rural area. In both contexts the response against tetanus toxoid was not influenced by the β-globin genotype. These findings suggest that both HbC and HbS affect the early development of naturally acquired immunity against malaria. The enhanced immune reactivity in both HbC and HbS carriers supports the hypothesis that the protection against malaria of these adaptive genotypes might be at least partially mediated by acquired immunity against malaria
Should the Arteriovenous Fistula Be Created before Starting Dialysis?: A Decision Analytic Approach
Background: An arteriovenous fistula (AVF) is considered the vascular access of choice, but uncertainty exists about the\ud
optimal time for its creation in pre-dialysis patients. The aim of this study was to determine the optimal vascular access\ud
referral strategy for stage 4 (glomerular filtration rate ,30 ml/min/1.73 m2) chronic kidney disease patients using a decision\ud
analytic framework.\ud
Methods: A Markov model was created to compare two strategies: refer all stage 4 chronic kidney disease patients for an\ud
AVF versus wait until the patient starts dialysis. Data from published observational studies were used to estimate the\ud
probabilities used in the model. A Markov cohort analysis was used to determine the optimal strategy with life expectancy\ud
and quality adjusted life expectancy as the outcomes. Sensitivity analyses, including a probabilistic sensitivity analysis, were\ud
performed using Monte Carlo simulation.\ud
Results: The wait strategy results in a higher life expectancy (66.6 versus 65.9 months) and quality adjusted life expectancy\ud
(38.9 versus 38.5 quality adjusted life months) than immediate AVF creation. It was robust across all the parameters except\ud
at higher rates of progression and lower rates of ischemic steal syndrome.\ud
Conclusions: Early creation of an AVF, as recommended by most guidelines, may not be the preferred strategy in all predialysis\ud
patients. Further research on cost implications and patient preferences for treatment options needs to be done\ud
before recommending early AVF creation
A Universal Power-law Prescription for Variability from Synthetic Images of Black Hole Accretion Flows
We present a framework for characterizing the spatiotemporal power spectrum of the variability expected from the horizon-scale emission structure around supermassive black holes, and we apply this framework to a library of general relativistic magnetohydrodynamic (GRMHD) simulations and associated general relativistic ray-traced images relevant for Event Horizon Telescope (EHT) observations of Sgr A*. We find that the variability power spectrum is generically a red-noise process in both the temporal and spatial dimensions, with the peak in power occurring on the longest timescales and largest spatial scales. When both the time-averaged source structure and the spatially integrated light-curve variability are removed, the residual power spectrum exhibits a universal broken power-law behavior. On small spatial frequencies, the residual power spectrum rises as the square of the spatial frequency and is proportional to the variance in the centroid of emission. Beyond some peak in variability power, the residual power spectrum falls as that of the time-averaged source structure, which is similar across simulations; this behavior can be naturally explained if the variability arises from a multiplicative random field that has a steeper high-frequency power-law index than that of the time-averaged source structure. We briefly explore the ability of power spectral variability studies to constrain physical parameters relevant for the GRMHD simulations, which can be scaled to provide predictions for black holes in a range of systems in the optically thin regime. We present specific expectations for the behavior of the M87* and Sgr A* accretion flows as observed by the EHT
Penilaian Kinerja Keuangan Koperasi di Kabupaten Pelalawan
This paper describe development and financial performance of cooperative in District Pelalawan among 2007 - 2008. Studies on primary and secondary cooperative in 12 sub-districts. Method in this stady use performance measuring of productivity, efficiency, growth, liquidity, and solvability of cooperative. Productivity of cooperative in Pelalawan was highly but efficiency still low. Profit and income were highly, even liquidity of cooperative very high, and solvability was good
Juxtaposing BTE and ATE – on the role of the European insurance industry in funding civil litigation
One of the ways in which legal services are financed, and indeed shaped, is through private insurance arrangement. Two contrasting types of legal expenses insurance contracts (LEI) seem to dominate in Europe: before the event (BTE) and after the event (ATE) legal expenses insurance. Notwithstanding institutional differences between different legal systems, BTE and ATE insurance arrangements may be instrumental if government policy is geared towards strengthening a market-oriented system of financing access to justice for individuals and business. At the same time, emphasizing the role of a private industry as a keeper of the gates to justice raises issues of accountability and transparency, not readily reconcilable with demands of competition. Moreover, multiple actors (clients, lawyers, courts, insurers) are involved, causing behavioural dynamics which are not easily predicted or influenced.
Against this background, this paper looks into BTE and ATE arrangements by analysing the particularities of BTE and ATE arrangements currently available in some European jurisdictions and by painting a picture of their respective markets and legal contexts. This allows for some reflection on the performance of BTE and ATE providers as both financiers and keepers. Two issues emerge from the analysis that are worthy of some further reflection. Firstly, there is the problematic long-term sustainability of some ATE products. Secondly, the challenges faced by policymakers that would like to nudge consumers into voluntarily taking out BTE LEI
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