77 research outputs found
Age-dependent differences in human brain activity using a face- and location-matching task: An fMRI study
Purpose: To evaluate the differences of cortical activation patterns in young and elderly healthy subjects for object and spatial visual processing using a face- and location-matching task. Materials and Methods: We performed a face- and a location-matching task in 15 young (mean age: 28 +/- 9 years) and 19 elderly (mean age: 71 +/- 6 years) subjects. Each experiment consisted of 7 blocks alternating between activation and control condition. For face matching, the subjects had to indicate whether two displayed faces were identical or different. For location matching, the subjects had to press a button whenever two objects had an identical position. For control condition, we used a perception task with abstract images. Functional imaging was performed on a 1.5-tesla scanner using an EPI sequence. Results: In the face-matching task, the young subjects showed bilateral (right 1 left) activation in the occipito-temporal pathway (occipital gyrus, inferior and middle temporal gyrus). Predominantly right hemispheric activations were found in the fusiform gyrus, the right dorsolateral prefrontal cortex (inferior and middle frontal gyrus) and the superior parietal gyrus. In the elderly subjects, the activated areas in the right fronto-lateral cortex increased. An additional activated area could be found in the medial frontal gyrus (right > left). In the location-matching task, young subjects presented increased bilateral (right > left) activation in the superior parietal lobe and precuneus compared with face matching. The activations in the occipito-temporal pathway, in the right fronto-lateral cortex and the fusiform gyrus were similar to the activations found in the face-matching task. In the elderly subjects, we detected similar activation patterns compared to the young subjects with additional activations in the medial frontal gyrus. Conclusion: Activation patterns for object-based and spatial visual processing were established in the young and elderly healthy subjects. Differences between the elderly and young subjects could be evaluated, especially by using a face-matching task. Copyright (c) 2007 S. Karger AG, Basel
Global and regional estimates of cancer mortality and incidence by site: II. results for the global burden of disease 2000
BACKGROUND: Mortality estimates alone are not sufficient to understand the true magnitude of cancer burden. We present the detailed estimates of mortality and incidence by site as the basis for the future estimation of cancer burden for the Global Burden of Disease 2000 study. METHODS: Age- and sex- specific mortality envelope for all malignancies by region was derived from the analysis of country life-tables and cause of death. We estimated the site-specific cancer mortality distributions from vital records and cancer survival model. The regional cancer mortality by site is estimated by disaggregating the regional cancer mortality envelope based on the mortality distribution. Estimated incidence-to-mortality rate ratios were used to back calculate the final cancer incidence estimates by site. RESULTS: In 2000, cancer accounted for over 7 million deaths (13% of total mortality) and there were more than 10 million new cancer cases world wide in 2000. More than 60% of cancer deaths and approximately half of new cases occurred in developing regions. Lung cancer was the most common cancers in the world, followed by cancers of stomach, liver, colon and rectum, and breast. There was a significant variations in the distribution of site-specific cancer mortality and incidence by region. CONCLUSIONS: Despite a regional variation, the most common cancers are potentially preventable. Cancer burden estimation by taking into account both mortality and morbidity is an essential step to set research priorities and policy formulation. Also it can used for setting priorities when combined with data on costs of interventions against cancers
The Gaia-ESO Survey: Chromospheric Emission, Accretion Properties, and Rotation in Velorum and Chamaeleon I
We use the fundamental parameters delivered by the GES consortium in the
first internal data release to select the members of Vel and Cha I
among the UVES and GIRAFFE spectroscopic observations. A total of 140
Vel members and 74 Cha I members were studied. We calculated stellar
luminosities through spectral energy distributions, while stellar masses were
derived by comparison with evolutionary tracks. The spectral subtraction of
low-activity and slowly rotating templates, which are rotationally broadened to
match the of the targets, enabled us to measure the equivalent widths
(EWs) and the fluxes in the H and H lines. The H line
was also used for identifying accreting objects and for evaluating the mass
accretion rate (). The distribution of for the
members of Vel displays a peak at about 10 km s with a tail
toward faster rotators. There is also some indication of a different
distribution for the members of its two kinematical populations. Only a handful
of stars in Vel display signatures of accretion, while many more
accretors were detected in the younger Cha~I. Accreting and active stars occupy
two different regions in a -flux diagram and we propose a
criterion for distinguishing them. We derive in the ranges
-yr and -yr
for Vel and Cha I accretors, respectively. We find less scatter in the
relation derived through the H EWs, when
compared to the H diagnostics, in agreement with other authors
The Gaia-ESO Survey: a kinematical and dynamical study of four young open clusters
Context.
The origin and dynamical evolution of star clusters is an important topic in stellar astrophysics. Several models have been
proposed to understand the formation of bound and unbound clusters and their evolution, and these can be tested by examining the
kinematical and dynamical properties of clusters over a wide range of ages and masses.
Aims.
We use the
Gaia
-ESO Survey products to study four open clusters (IC 2602, IC 2391, IC 4665, and NGC 2547) that lie in the
age range between 20 and 50 Myr.
Methods.
We employ the gravity index
γ
and the equivalent width of the lithium line at 6708 Å, together with e
ff
ective temperature
T
e
ff
, and the metallicity of the stars in order to discard observed contaminant stars. Then, we derive the cluster radial velocity disper-
sions
σ
c
, the total cluster mass M
tot
, and the half mass radius
r
hm
. Using the
Gaia
-DR1 TGAS catalogue, we independently derive the
intrinsic velocity dispersion of the clusters from the astrometric parameters of cluster members.
Results.
The intrinsic radial velocity dispersions derived by the spectroscopic data are larger than those derived from the TGAS data,
possibly due to the di
ff
erent masses of the considered stars. Using M
tot
and
r
hm
we derive the virial velocity dispersion
σ
v
ir
and we
find that three out of four clusters are supervirial. This result is in agreement with the hypothesis that these clusters are dispersing, as
predicted by the "residual gas expulsion" scenario. However, recent simulations show that the virial ratio of young star clusters may
be overestimated if it is determined using the global velocity dispersion, since the clusters are not fully relaxed
The Gaia-ESO Survey: Chromospheric Emission, Accretion Properties, and Rotation in Velorum and Chamaeleon I
We use the fundamental parameters delivered by the GES consortium in the first internal data release to select the members of Vel and Cha I among the UVES and GIRAFFE spectroscopic observations. A total of 140 Vel members and 74 Cha I members were studied. We calculated stellar luminosities through spectral energy distributions, while stellar masses were derived by comparison with evolutionary tracks. The spectral subtraction of low-activity and slowly rotating templates, which are rotationally broadened to match the of the targets, enabled us to measure the equivalent widths (EWs) and the fluxes in the H and H lines. The H line was also used for identifying accreting objects and for evaluating the mass accretion rate (). The distribution of for the members of Vel displays a peak at about 10 km s with a tail toward faster rotators. There is also some indication of a different distribution for the members of its two kinematical populations. Only a handful of stars in Vel display signatures of accretion, while many more accretors were detected in the younger Cha~I. Accreting and active stars occupy two different regions in a -flux diagram and we propose a criterion for distinguishing them. We derive in the ranges -yr and -yr for Vel and Cha I accretors, respectively. We find less scatter in the relation derived through the H EWs, when compared to the H diagnostics, in agreement with other authors
The Gaia-ESO Survey: Structural and dynamical properties of the young cluster Chamaeleon i
The young (~2 Myr) cluster Chamaeleon I is one of the closest laboratories to
study the early stages of star cluster dynamics in a low-density environment.
We studied its structural and kinematical properties combining parameters from
the high-resolution spectroscopic survey Gaia-ESO with data from the
literature. Our main result is the evidence of a large discrepancy between the
velocity dispersion (sigma = 1.14 \pm 0.35 km s^{-1}) of the stellar population
and the dispersion of the pre-stellar cores (~0.3 km s^{-1}) derived from
submillimeter observations. The origin of this discrepancy, which has been
observed in other young star clusters is not clear. It may be due to either the
effect of the magnetic field on the protostars and the filaments, or to the
dynamical evolution of stars driven by two-body interactions. Furthermore, the
analysis of the kinematic properties of the stellar population put in evidence
a significant velocity shift (~1 km s^{-1}) between the two sub-clusters
located around the North and South main clouds. This result further supports a
scenario, where clusters form from the evolution of multiple substructures
rather than from a monolithic collapse.
Using three independent spectroscopic indicators (the gravity indicator
, the equivalent width of the Li line, and the H_alpha 10\% width), we
performed a new membership selection. We found six new cluster members located
in the outer region of the cluster. Starting from the positions and masses of
the cluster members, we derived the level of substructure Q, the surface
density \Sigma and the level of mass segregation of the
cluster. The comparison between these structural properties and the results of
N-body simulations suggests that the cluster formed in a low density
environment, in virial equilibrium or supervirial, and highly substructured
An update of the Worldwide Integrated Assessment (WIA) on systemic insecticides. Part 2: impacts on organisms and ecosystems
New information on the lethal and sublethal effects of neonicotinoids and fipronil on organisms is presented in this review, complementing the previous WIA in 2015. The high toxicity of these systemic insecticides to invertebrates has been confirmed and expanded to include more species and compounds. Most of the recent research has focused on bees and the sublethal and ecological impacts these insecticides have on pollinators. Toxic effects on other invertebrate taxa also covered predatory and parasitoid natural enemies and aquatic arthropods. Little, while not much new information has been gathered on soil organisms. The impact on marine coastal ecosystems is still largely uncharted. The chronic lethality of neonicotinoids to insects and crustaceans, and the strengthened evidence that these chemicals also impair the immune system and reproduction, highlights the dangers of this particular insecticidal classneonicotinoids and fipronil. , withContinued large scale – mostly prophylactic – use of these persistent organochlorine pesticides has the potential to greatly decreasecompletely eliminate populations of arthropods in both terrestrial and aquatic environments. Sublethal effects on fish, reptiles, frogs, birds and mammals are also reported, showing a better understanding of the mechanisms of toxicity of these insecticides in vertebrates, and their deleterious impacts on growth, reproduction and neurobehaviour of most of the species tested. This review concludes with a summary of impacts on the ecosystem services and functioning, particularly on pollination, soil biota and aquatic invertebrate communities, thus reinforcing the previous WIA conclusions (van der Sluijs et al. 2015)
A Compact Dication Source for Ba Tagging and Heavy Metal Ion Sensor Development
We present a tunable metal ion beam that delivers controllable ion currents
in the picoamp range for testing of dry-phase ion sensors. Ion beams are formed
by sequential atomic evaporation and single or multiple electron impact
ionization, followed by acceleration into a sensing region. Controllability of
the ionic charge state is achieved through tuning of electrode potentials that
influence the retention time in the ionization region. Barium, lead, and cobalt
samples have been used to test the system, with ion currents identified and
quantified using a quadrupole mass analyzer. Realization of a clean
ion beam within a bench-top system represents an important
technical advance toward the development and characterization of barium tagging
systems for neutrinoless double beta decay searches in xenon gas. This system
also provides a testbed for investigation of novel ion sensing methodologies
for environmental assay applications, with dication beams of Pb and
Cd also demonstrated for this purpose
Why Are Outcomes Different for Registry Patients Enrolled Prospectively and Retrospectively? Insights from the Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF).
Background: Retrospective and prospective observational studies are designed to reflect real-world evidence on clinical practice, but can yield conflicting results. The GARFIELD-AF Registry includes both methods of enrolment and allows analysis of differences in patient characteristics and outcomes that may result. Methods and Results: Patients with atrial fibrillation (AF) and ≥1 risk factor for stroke at diagnosis of AF were recruited either retrospectively (n = 5069) or prospectively (n = 5501) from 19 countries and then followed prospectively. The retrospectively enrolled cohort comprised patients with established AF (for a least 6, and up to 24 months before enrolment), who were identified retrospectively (and baseline and partial follow-up data were collected from the emedical records) and then followed prospectively between 0-18 months (such that the total time of follow-up was 24 months; data collection Dec-2009 and Oct-2010). In the prospectively enrolled cohort, patients with newly diagnosed AF (≤6 weeks after diagnosis) were recruited between Mar-2010 and Oct-2011 and were followed for 24 months after enrolment. Differences between the cohorts were observed in clinical characteristics, including type of AF, stroke prevention strategies, and event rates. More patients in the retrospectively identified cohort received vitamin K antagonists (62.1% vs. 53.2%) and fewer received non-vitamin K oral anticoagulants (1.8% vs . 4.2%). All-cause mortality rates per 100 person-years during the prospective follow-up (starting the first study visit up to 1 year) were significantly lower in the retrospective than prospectively identified cohort (3.04 [95% CI 2.51 to 3.67] vs . 4.05 [95% CI 3.53 to 4.63]; p = 0.016). Conclusions: Interpretations of data from registries that aim to evaluate the characteristics and outcomes of patients with AF must take account of differences in registry design and the impact of recall bias and survivorship bias that is incurred with retrospective enrolment. Clinical Trial Registration: - URL: http://www.clinicaltrials.gov . Unique identifier for GARFIELD-AF (NCT01090362)
Global surveillance of cancer survival 1995-2009: analysis of individual data for 25,676,887 patients from 279 population-based registries in 67 countries (CONCORD-2)
BACKGROUND:
Worldwide data for cancer survival are scarce. We aimed to initiate worldwide surveillance of cancer survival by central analysis of population-based registry data, as a metric of the effectiveness of health systems, and to inform global policy on cancer control.
METHODS:
Individual tumour records were submitted by 279 population-based cancer registries in 67 countries for 25·7 million adults (age 15-99 years) and 75,000 children (age 0-14 years) diagnosed with cancer during 1995-2009 and followed up to Dec 31, 2009, or later. We looked at cancers of the stomach, colon, rectum, liver, lung, breast (women), cervix, ovary, and prostate in adults, and adult and childhood leukaemia. Standardised quality control procedures were applied; errors were corrected by the registry concerned. We estimated 5-year net survival, adjusted for background mortality in every country or region by age (single year), sex, and calendar year, and by race or ethnic origin in some countries. Estimates were age-standardised with the International Cancer Survival Standard weights.
FINDINGS:
5-year survival from colon, rectal, and breast cancers has increased steadily in most developed countries. For patients diagnosed during 2005-09, survival for colon and rectal cancer reached 60% or more in 22 countries around the world; for breast cancer, 5-year survival rose to 85% or higher in 17 countries worldwide. Liver and lung cancer remain lethal in all nations: for both cancers, 5-year survival is below 20% everywhere in Europe, in the range 15-19% in North America, and as low as 7-9% in Mongolia and Thailand. Striking rises in 5-year survival from prostate cancer have occurred in many countries: survival rose by 10-20% between 1995-99 and 2005-09 in 22 countries in South America, Asia, and Europe, but survival still varies widely around the world, from less than 60% in Bulgaria and Thailand to 95% or more in Brazil, Puerto Rico, and the USA. For cervical cancer, national estimates of 5-year survival range from less than 50% to more than 70%; regional variations are much wider, and improvements between 1995-99 and 2005-09 have generally been slight. For women diagnosed with ovarian cancer in 2005-09, 5-year survival was 40% or higher only in Ecuador, the USA, and 17 countries in Asia and Europe. 5-year survival for stomach cancer in 2005-09 was high (54-58%) in Japan and South Korea, compared with less than 40% in other countries. By contrast, 5-year survival from adult leukaemia in Japan and South Korea (18-23%) is lower than in most other countries. 5-year survival from childhood acute lymphoblastic leukaemia is less than 60% in several countries, but as high as 90% in Canada and four European countries, which suggests major deficiencies in the management of a largely curable disease.
INTERPRETATION:
International comparison of survival trends reveals very wide differences that are likely to be attributable to differences in access to early diagnosis and optimum treatment. Continuous worldwide surveillance of cancer survival should become an indispensable source of information for cancer patients and researchers and a stimulus for politicians to improve health policy and health-care systems
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