108 research outputs found
Mining the ESO WFI and INT WFC archives for known Near Earth Asteroids. Mega-Precovery software
The ESO/MPG WFI and the INT WFC wide field archives comprising 330,000 images
were mined to search for serendipitous encounters of known Near Earth Asteroids
(NEAs) and Potentially Hazardous Asteroids (PHAs). A total of 152 asteroids (44
PHAs and 108 other NEAs) were identified using the PRECOVERY software, their
astrometry being measured on 761 images and sent to the Minor Planet Centre.
Both recoveries and precoveries were reported, including prolonged orbital arcs
for 18 precovered objects and 10 recoveries. We analyze all new opposition data
by comparing the orbits fitted before and after including our contributions. We
conclude the paper presenting Mega-Precovery, a new online service focused on
data mining of many instrument archives simultaneously for one or a few given
asteroids. A total of 28 instrument archives have been made available for
mining using this tool, adding together about 2.5 million images forming the
Mega-Archive.Comment: Accepted for publication in Astronomische Nachrichten (Sep 2012
Insights into the Second Law of Thermodynamics from Anisotropic Gas-Surface Interactions
Thermodynamic implications of anisotropic gas-surface interactions in a
closed molecular flow cavity are examined. Anisotropy at the microscopic scale,
such as might be caused by reduced-dimensionality surfaces, is shown to lead to
reversibility at the macroscopic scale. The possibility of a self-sustaining
nonequilibrium stationary state induced by surface anisotropy is demonstrated
that simultaneously satisfies flux balance, conservation of momentum, and
conservation of energy. Conversely, it is also shown that the second law of
thermodynamics prohibits anisotropic gas-surface interactions in "equilibrium",
even for reduced dimensionality surfaces. This is particularly startling
because reduced dimensionality surfaces are known to exhibit a plethora of
anisotropic properties. That gas-surface interactions would be excluded from
these anisotropic properties is completely counterintuitive from a causality
perspective. These results provide intriguing insights into the second law of
thermodynamics and its relation to gas-surface interaction physics.Comment: 28 pages, 11 figure
High-dimensional quantum dynamics of adsorption and desorption of H at Cu(111)
We performed high-dimensional quantum dynamical calculations of the
dissociative adsorption and associative desorption of hydrogen on Cu(111). The
potential energy surface (PES) is obtained from density functional theory
calculations. Two regimes of dynamics are found, at low energies sticking is
determined by the minimum energy barrier, at high energies by the distribution
of barrier heights. Experimental results are well-reproduced qualitatively, but
some quantitative discrepancies are identified as well.Comment: 4 two column pages, revtex, 4 figures, to appear in Phys. Rev. Let
Local management and landscape composition affect predatory mites in European wine-growing regions
Sustainable land use in agricultural landscapes is essential to counteract the global decline of biodiversity, as well to ensure ecosystem services like natural pest control. Phytoseiid mites are key natural enemies of pest mites in vineyards but how local management and landscape context affect phytoseiid mites remains poorly known. In this study, we examined the effects of farming systems, inter-row management and landscape composition on phytoseiid mite communities in 156 vineyards across five European wine-growing regions. Our results showed that phytoseiid communities were mainly dominated by one or two phytoseiid species across Europe and that local management was a major factor affecting population densities. According to the wine-growing regions, phytoseiid mite densities benefited from integrated pest management or conventional farming compared to organic farming and from spontaneous vegetation cover compared to seeded cover crops. Moreover, mite densities benefited from increasing proportions of vineyards at the landscape scale. The farming systems effects were most likely related to the positive impact of the lower pesticide use in integrated and conventional vineyards. The positive effect of spontaneous vegetation cover could be related to a better supply of nutritive pollen as food resource compared to seeded cover crops, which depends on the plant species in the inter-row. Our findings indicated accordingly that a reduced pesticide use, and inter-row management are crucial factors for promoting pest control by predatory mites in European vineyards. Moreover, the proportion of viticultural area in the landscape is a considerable factor to retain stable phytoseiid mite populations.This research was funded by the research project SECBIVIT, which was funded through the 2017-2018 Belmont Forum and BiodivERsA joint call for research proposals, under the BiodivScen ERA-Net COFUND program, with the funding organizations: Agencia Estatal de Investigación (Ministerio de ciencia e innovación/ES/Grant #10.13039/501100011033), Austrian Science Fund (AT/Grant #I 4025-B32), Federal Ministry of Education and Research and Projektträger VDI/VDE Innovation + Technik GmbH (DE), French National Research Agency (FR), Netherlands Organisation for Scientific Research (NL), National Science Foundation (US/Grant #1850943) and Romanian Executive Agency for Higher Education, Research, Development and Innovation Funding (RO)
EURONEAR - Recovery, Follow-up and Discovery of NEAs and MBAs using Large Field 1-2m Telescopes
We report on the follow-up and recovery of 100 program NEAs, PHAs and VIs
using the ESO/MPG 2.2m, Swope 1m and INT 2.5m telescopes equipped with large
field cameras. The 127 fields observed during 11 nights covered 29 square
degrees. Using these data, we present the incidental survey work which includes
558 known MBAs and 628 unknown moving objects mostly consistent with MBAs from
which 58 objects became official discoveries. We planned the runs using six
criteria and four servers which focus mostly on faint and poorly observed
objects in need of confirmation, follow-up and recovery. We followed 62 faint
NEAs within one month after discovery and we recovered 10 faint NEAs having big
uncertainties at their second or later opposition. Using the INT we eliminated
4 PHA candidates and VIs. We observed in total 1,286 moving objects and we
reported more than 10,000 positions. All data were reduced by the members of
our network in a team effort, and reported promptly to the MPC. The positions
of the program NEAs were published in 27 MPC and MPEC references and used to
improve their orbits. The O-C residuals for known MBAs and program NEAs are
smallest for the ESO/MPG and Swope and about four times larger for the INT
whose field is more distorted. The incidental survey allowed us to study
statistics of the MBA and NEA populations observable today with 1--2m
facilities. We calculate preliminary orbits for all unknown objects,
classifying them as official discoveries, later identifications and unknown
outstanding objects. The orbital elements a, e, i calculated by FIND_ORB
software for the official discoveries and later identified objects are very
similar with the published elements which take into account longer
observational arcs; thus preliminary orbits were used in statistics for the
whole unknown dataset. (CONTINUED)Comment: Accepted in Planetary and Space Science (Aug 2011
Decoherence, fluctuations and Wigner function in neutron optics
We analyze the coherence properties of neutron wave packets, after they have
interacted with a phase shifter undergoing different kinds of statistical
fluctuations. We give a quantitative (and operational) definition of
decoherence and compare it to the standard deviation of the distribution of the
phase shifts. We find that in some cases the neutron ensemble is more coherent,
even though it has interacted with a wider (i.e. more disordered) distribution
of shifts. This feature is independent of the particular definition of
decoherence: this is shown by proposing and discussing an alternative
definition, based on the Wigner function, that displays a similar behavior. We
briefly discuss the notion of entropy of the shifts and find that, in general,
it does not correspond to that of decoherence of the neutron.Comment: 18 pages, 7 figure
Parenting and child adjustment: a comparison of Turkish and English families
The links between parenting and child behaviour in cultural context have received increasing research attention. We investigated the effect of parenting on child adjustment using a multi-method design, comparing English and Turkish families. The socioeconomically diverse samples included 118 English and 100 Turkish families, each with two children aged 4–8 years. Mothers completed questionnaires as well as parent–child interaction being assessed using a structured Etch-a-Sketch task with each child separately. Children were interviewed about their relationships with their mothers using the Berkeley Puppet Interview. Multiple-group Confirmatory Analysis was used to test Measurement Invariance across groups, and a multi-informant approach was used to assess parenting. We found partial cross-cultural measurement invariance for parenting and child adjustment. Strikingly, the association between parenting and child adjustment was stronger among English families than Turkish families. Culturally distinct meanings of both parenting and child behaviour must be considered when interpreting their association
Global Retinoblastoma Presentation and Analysis by National Income Level
Importance: Early diagnosis of retinoblastoma, the most common intraocular cancer, can save both a child's life and vision. However, anecdotal evidence suggests that many children across the world are diagnosed late. To our knowledge, the clinical presentation of retinoblastoma has never been assessed on a global scale. Objectives: To report the retinoblastoma stage at diagnosis in patients across the world during a single year, to investigate associations between clinical variables and national income level, and to investigate risk factors for advanced disease at diagnosis. Design, Setting, and Participants: A total of 278 retinoblastoma treatment centers were recruited from June 2017 through December 2018 to participate in a cross-sectional analysis of treatment-naive patients with retinoblastoma who were diagnosed in 2017. Main Outcomes and Measures: Age at presentation, proportion of familial history of retinoblastoma, and tumor stage and metastasis. Results: The cohort included 4351 new patients from 153 countries; the median age at diagnosis was 30.5 (interquartile range, 18.3-45.9) months, and 1976 patients (45.4%) were female. Most patients (n = 3685 [84.7%]) were from low- A nd middle-income countries (LMICs). Globally, the most common indication for referral was leukocoria (n = 2638 [62.8%]), followed by strabismus (n = 429 [10.2%]) and proptosis (n = 309 [7.4%]). Patients from high-income countries (HICs) were diagnosed at a median age of 14.1 months, with 656 of 666 (98.5%) patients having intraocular retinoblastoma and 2 (0.3%) having metastasis. Patients from low-income countries were diagnosed at a median age of 30.5 months, with 256 of 521 (49.1%) having extraocular retinoblastoma and 94 of 498 (18.9%) having metastasis. Lower national income level was associated with older presentation age, higher proportion of locally advanced disease and distant metastasis, and smaller proportion of familial history of retinoblastoma. Advanced disease at diagnosis was more common in LMICs even after adjusting for age (odds ratio for low-income countries vs upper-middle-income countries and HICs, 17.92 [95% CI, 12.94-24.80], and for lower-middle-income countries vs upper-middle-income countries and HICs, 5.74 [95% CI, 4.30-7.68]). Conclusions and Relevance: This study is estimated to have included more than half of all new retinoblastoma cases worldwide in 2017. Children from LMICs, where the main global retinoblastoma burden lies, presented at an older age with more advanced disease and demonstrated a smaller proportion of familial history of retinoblastoma, likely because many do not reach a childbearing age. Given that retinoblastoma is curable, these data are concerning and mandate intervention at national and international levels. Further studies are needed to investigate factors, other than age at presentation, that may be associated with advanced disease in LMICs
Travel burden and clinical presentation of retinoblastoma: analysis of 1024 patients from 43 African countries and 518 patients from 40 European countries
BACKGROUND: The travel distance from home to a treatment centre, which may impact the stage at diagnosis, has not been investigated for retinoblastoma, the most common childhood eye cancer. We aimed to investigate the travel burden and its impact on clinical presentation in a large sample of patients with retinoblastoma from Africa and Europe. METHODS: A cross-sectional analysis including 518 treatment-naĂŻve patients with retinoblastoma residing in 40 European countries and 1024 treatment-naĂŻve patients with retinoblastoma residing in 43 African countries. RESULTS: Capture rate was 42.2% of expected patients from Africa and 108.8% from Europe. African patients were older (95% CI -12.4 to -5.4, p<0.001), had fewer cases of familial retinoblastoma (95% CI 2.0 to 5.3, p<0.001) and presented with more advanced disease (95% CI 6.0 to 9.8, p<0.001); 43.4% and 15.4% of Africans had extraocular retinoblastoma and distant metastasis at the time of diagnosis, respectively, compared to 2.9% and 1.0% of the Europeans. To reach a retinoblastoma centre, European patients travelled 421.8 km compared to Africans who travelled 185.7 km (p<0.001). On regression analysis, lower-national income level, African residence and older age (p<0.001), but not travel distance (p=0.19), were risk factors for advanced disease. CONCLUSIONS: Fewer than half the expected number of patients with retinoblastoma presented to African referral centres in 2017, suggesting poor awareness or other barriers to access. Despite the relatively shorter distance travelled by African patients, they presented with later-stage disease. Health education about retinoblastoma is needed for carers and health workers in Africa in order to increase capture rate and promote early referral
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