443 research outputs found
X-ray scaling relations from a complete sample of the richest maxBCG clusters
We use a complete sample of 38 richest maxBCG clusters to study the
ICM-galaxy scaling relations and the halo mass selection properties of the
maxBCG algorithm, based on X-ray and optical observations. The clusters are
selected from the two largest bins of optical richness in the Planck stacking
work with the maxBCG richness . We analyze their Chandra and
XMM-Newton data to derive the X-ray properties of the ICM. We then use the
distribution of , , to study the mass selection
of maxBCG. Compared with previous works based on the whole richness
sample, a significant fraction of blended systems with boosted richness is
skewed into this richest sample. Parts of the blended halos are picked apart by
the redMaPPer, an updated red-sequence cluster finding algorithm with lower
mass scatter. Moreover, all the optical blended halos are resolved as
individual X-ray halos, following the established and
relations. We further discuss that the discrepancy between ICM-galaxy scaling
relations, especially for future blind stacking, can come from several factors,
including miscentering, projection, contamination of low mass systems, mass
bias and covariance bias. We also evaluate the fractions of relaxed and cool
core clusters in our sample. Both are smaller than those from SZ or X-ray
selected samples. Moreover, disturbed clusters show a higher level of mass bias
than relaxed clusters.Comment: 28 pages, 12 figures, MNRAS in pres
Young adult born neurons enhance hippocampal dependent performance via influences on bilateral networks
Adult neurogenesis supports performance in many hippocampal dependent tasks. Considering the small number of adult-born neurons generated at any given time, it is surprising that this sparse population of cells can substantially influence behavior. Recent studies have demonstrated that heightened excitability and plasticity may be critical for the contribution of young adult-born cells for certain tasks. What is not well understood is how these unique biophysical and synaptic properties may translate to networks that support behavioral function. Here we employed a location discrimination task in mice while using optogenetics to transiently silence adult-born neurons at different ages. We discovered that adult-born neurons promote location discrimination during early stages of development but only if they undergo maturation during task acquisition. Silencing of young adult-born neurons also produced changes extending to the contralateral hippocampus, detectable by both electrophysiology and fMRI measurements, suggesting young neurons may modulate location discrimination through influences on bilateral hippocampal networks.United States. National Institutes of Health (1DP2NS082126)National Institute of Mental Health (U.S.) (5R00MH085944)United States. National Institutes of Health (R01-DA028299)United States. Defense Advanced Research Projects Agency (W911NF-10-0059)Pew Charitable TrustsAmerican Federation for Aging ResearchAlfred P. Sloan FoundationNational Institute of Mental Health (U.S.) (1R21MH109941
Low potency toxins reveal dense interaction networks in metabolism
Background
The chemicals of metabolism are constructed of a small set of atoms and bonds. This may be because chemical structures outside the chemical space in which life operates are incompatible with biochemistry, or because mechanisms to make or utilize such excluded structures has not evolved. In this paper I address the extent to which biochemistry is restricted to a small fraction of the chemical space of possible chemicals, a restricted subset that I call Biochemical Space. I explore evidence that this restriction is at least in part due to selection again specific structures, and suggest a mechanism by which this occurs.
Results
Chemicals that contain structures that our outside Biochemical Space (UnBiological groups) are more likely to be toxic to a wide range of organisms, even though they have no specifically toxic groups and no obvious mechanism of toxicity. This correlation of UnBiological with toxicity is stronger for low potency (millimolar) toxins. I relate this to the observation that most chemicals interact with many biological structures at low millimolar toxicity. I hypothesise that life has to select its components not only to have a specific set of functions but also to avoid interactions with all the other components of life that might degrade their function.
Conclusions
The chemistry of life has to form a dense, self-consistent network of chemical structures, and cannot easily be arbitrarily extended. The toxicity of arbitrary chemicals is a reflection of the disruption to that network occasioned by trying to insert a chemical into it without also selecting all the other components to tolerate that chemical. This suggests new ways to test for the toxicity of chemicals, and that engineering organisms to make high concentrations of materials such as chemical precursors or fuels may require more substantial engineering than just of the synthetic pathways involved
AGN feedback in the FR II galaxy 3C 220.1
We present results from a deep (174 ks) Chandra observation of the FR-II
radio galaxy 3C 220.1, the central brightest cluster galaxy (BCG) of a 4 keV cluster at . The temperature of the hot cluster medium
drops from keV to keV at 35 kpc radius, while the
temperature at smaller radii may be substantially lower. The central active
galactic nucleus (AGN) outshines the whole cluster in X-rays, with a bolometric
luminosity of erg s (% of the Eddington
rate). The system shows a pair of potential X-ray cavities kpc east
and west of the nucleus. The cavity power is estimated within the range of
erg s and erg s, from
different methods. The X-ray enhancements in the radio lobes could be due to
inverse Compton emission, with a total 2-10 keV luminosity of
erg s. We compare 3C 220.1 with other cluster
BCGs, including Cygnus A, as there are few BCGs in rich clusters hosting an
FR-II galaxy. We also summarize the jet power of FR-II galaxies from different
methods. The comparison suggests that the cavity power of FR-II galaxies likely
under-estimates the jet power. The properties of 3C 220.1 suggest that it is at
the transition stage from quasar-mode feedback to radio-mode feedback.Comment: 14 pages, 13 figures, MNRAS accepte
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
OveRcoming Adverse ChiLdhood Experiences (ORACLE):A Mixed Methods Intervention Co-design Study to Improve Outcomes for Children and Young People Experiencing or at Risk of Adversity
Childhood exposures to adversity are common and increase risk for negative health and social outcomes throughout the life course. There is limited evidence regarding interventions to prevent or reduce the impact of adverse childhood experiences (ACEs), particularly for families with multiple adversities. Here we present the findings of mixed methods research to co-design a complex intervention to prevent adverse childhood experiences, and their impacts. Using established research methods, and the framework of the Medical Research Council (MRC) complex interventions development guidance, the work was conducted in four stages, shaped by stakeholder engagement and input at every stage. The first stage, Discover, was exploratory and employed evidence synthesis and quantitative (n = 11,564) and qualitative (n = 31) research methods to understand needs, experiences, and evidence gaps. The Define stage developed three intervention principles and identified intervention options, through a series of six co-design workshops with 41 participants and an academic research team workshop. The Develop and Deliver stages were undertaken through a Policy Lab (22 participants), and developed options for intervention design, before converging on a defined intervention that could be delivered and tested. Through this process, we developed a 'village-style' intervention, which functions at three levels: individual service users, operational, and system/strategy. Central to this are link or community health workers who would build relationships with family members, and act as a single point of contact. They should develop an understanding of family needs and the interaction of multiple complex adversities, and advocate for families, facilitating access to services. Crucially, they should use this understanding to work at and feed into operational and strategic levels to reshape services and enhance access for all families at risk of or experiencing adversity. Entry into the intervention through assessments at existing universal touch points, for example at routine perinatal or newborn appointments, should provide a prevention focus and follow the principles of proportionate universalism. Sensitive enquiry regarding financial stress may be a component of the assessment, in response to the findings of this work regarding the contexts created through the interaction of poverty and other adversities. The proposed intervention is designed to improve individual and family outcomes, and generate positive system-level changes. A feasibility study and evaluation will be required in future work, to assess the effects, costs and benefits. The processes and frameworks we developed and used may provide an adaptable template for future intervention co-design work
Chandra view of Abell 407: The central compact group of galaxies and the interaction between the radio AGN and the ICM
Abell 407 (A407) is a unique galaxy cluster hosting a central compact group of nine galaxies (named as 'Zwicky's Nonet'; G1 - G9 in this work) within a 30 kpc radius region. The cluster core also hosts a luminous radio active galactic nucleus (AGN), 4C 35.06 with helically twisted jets extending over 200 kpc. With a 44 ks Chandra observation of A407, we characterize the X-ray properties of its intracluster medium (ICM) and central galaxies. The mean X-ray temperature of A407 is 2.7 keV and the is . We suggest that A407 has a weak cool core at kpc scales and at its very center, -2 kpc radius, a small galaxy corona associated with the strong radio AGN. We also conclude that the AGN 4C 35.06 host galaxy is most likely G3. We suggest that the central group of galaxies is undergoing a `slow merge' procedure. The range of the merging time-scale is Gyr and the stellar mass of the future brightest cluster galaxy (BCG) will be . We find that the regions which overlap with the radio jets have higher temperature and metallicity. This is consistent with AGN feedback activity. The central entropy is higher than that for other clusters, which may be due to the AGN feedback and/or merging activity. With all these facts, we suggest that A407 is a unique and rare system in the local universe that could help us to understand the formation of a massive BCG
Groundwater Nitrogen Pollution and Assessment of Its Health Risks: A Case Study of a Typical Village in Rural-Urban Continuum, China
Protecting groundwater from nitrogen contamination is an important public-health concern and a major national environmental issue in China. In this study, we monitored water quality in 29 wells from 2009 to 2010 in a village in Shanghai city, whick belong to typical rural-urban continuum in China. The total N and NO3-N exhibited seasonal changes, and there were large fluctuations in NH4-N in residential areas, but without significant seasonal patterns. NO2-N in the water was not stable, but was present at high levels. Total N and NO3-N were significantly lower in residential areas than in agricultural areas. The groundwater quality in most wells belonged to Class III and IV in the Chinese water standard, which defines water that is unsuitable for human consumption. Our health risk assessments showed that NO3-N posed the greatest carcinogenic risk, with risk values ranging from 19×10−6 to 80×10−6, which accounted for more than 90% of the total risk in the study area
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