505 research outputs found

    Nearest neighbor embedding with different time delays

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    A nearest neighbor based selection of time delays for phase space reconstruction is proposed and compared to the standard use of time delayed mutual information. The possibility of using different time delays for consecutive dimensions is considered. A case study of numerically generated solutions of the Lorenz system is used for illustration. The effect of contamination with various levels of additive Gaussian white noise is discussed.Comment: 4 pages, 5 figures, updated to final versio

    Observation-based assessment of stratospheric fractional release, lifetimes, and ozone depletion potentials of ten important source gases

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    Estimates of the recovery time of stratospheric ozone heavily rely on the exact knowledge of the processes that lead to the decomposition of the relevant halogenated source gases. Crucial parameters in this context are fractional release factors (FRFs) as well as stratospheric lifetimes and ozone depletion potentials (ODPs). We here present data from the analysis of air samples collected between 2009 and 2011 on board research aircraft flying in the mid- and high-latitude stratosphere and infer the above-mentioned parameters for ten major source gases: CFCl3 (CFC-11), CF2Cl2 (CFC-12), CF2ClCFCl2 (CFC-113), CCl4 (carbon tetrachloride), CH3CCl3 (methyl chloroform), CHF2Cl (HCFC-22), CH3CFCl2 (HCFC-141b), CH3CF2Cl (HCFC-142b), CF2ClBr (H-1211), and CF3Br (H-1301). The inferred correlations of their FRFs with mean ages of air reveal less decomposition as compared to previous studies for most compounds. When using the calculated set of FRFs to infer equivalent stratospheric chlorine, we find a reduction of more than 20% as compared to the values inferred in the most recent Scientific Assessment of Ozone Depletion by the World Meteorological Organisation (WMO, 2011). We also note that FRFs and their correlations with mean age are not generally time-independent as often assumed. The stratospheric lifetimes were calculated relative to that of CFC-11. Within our uncertainties the ratios between stratospheric lifetimes inferred here agree with the values in recent WMO reports except for CFC-11, CFC-12 and CH3CCl3. Finally, we calculate lower ODPs than recommended by WMO for six out of ten compounds, with changes most pronounced for the three HCFCs. Collectively these newly calculated values may have important implications for the severity and recovery time of stratospheric ozone loss

    Infant Mortality Trends Among Georgia Residents, 1995-2003: Targeting Healthy People’s 2010 Goals

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    Population-based trends in infant mortality among Georgia Residents between 1995 and 2003 were assessed on characteristics such as race, birth weight, neonatal and post-neonatal periods, and cause of death. A statistical analysis was conducted to show that the Georgia infant mortality rate (IMR) remained constant throughout the study period and averaged 8.67 per 1,000 live births. The analysis revealed racial disparities, with an IMR ranging from 6.03 in white infants to 13.76 in black infants, with less than one percent (0.86%) change, on average, among the differences between black and white mortality rates across the nine-year period. The disparities were also evident in infants with low birth weight (LBW) and very low birth weight (VLBW). Black infants born with LBW (12.9%) and VLBW (9.98%) have more than twice the rate of infant mortality compared to white infants born with LBW (6.64%) and VLBW (1.12%). Mortality in the neonatal period accounted for more than half (67.96%) of all infant deaths and exhibited considerable ethnic differences. Among all groups, black male neonates (10.7) have the highest mortality rates. The average neonatal mortality rate across the entire study period is 5.89 (SD=0.20); the average postneonatal mortality rate across the entire study period is 2.78 (SD=0.22). The five leading causes of death among Georgian infants in descending order were: birth defects, prematurity and low birth weight, Sudden Unexplained Infant Deaths (SUID), other perinatal conditions and respiratory conditions with racial differences in the ordering

    A curious case of property privatization: two examples of the tragedy of the anticommons in Ho Chi Minh City-Vietnam

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    Contains fulltext : 166089pub.pdf (publisher's version ) (Open Access)This paper focuses on the influence of land and property privatization processes on urban development in Ho Chi Minh City (HCMC), Vietnam. Many scholars have recognized that the privatization policy regarding property and land use rights may create a fragmentation of private land ownership, which eventually can lead to what has been called the tragedy of the anticommons. This paper observes how this phenomenon has also threatened urban development in HCMC after the introduction of the Doi Moi policy. Two case studies show two different types of development processes in HCMC, namely a small self-development project and a large-scale commercial project. Both case studies reveal how (potential) tragedies of the anticommons can be solved in different ways.09 augustus 201

    Accelerating growth of HFC-227ea (1,1,1,2,3,3,3-heptafluoropropane) in the atmosphere

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    We report the first measurements of 1,1,1,2,3,3,3-heptafluoropropane (HFC-227ea), a substitute for ozone depleting compounds, in air samples originating from remote regions of the atmosphere and present evidence for its accelerating growth. Observed mixing ratios ranged from below 0.01 ppt in deep firn air to 0.59 ppt in the current northern mid-latitudinal upper troposphere. Firn air samples collected in Greenland were used to reconstruct a history of atmospheric abundance. Year-on-year increases were deduced, with acceleration in the growth rate from 0.029 ppt per year in 2000 to 0.056 ppt per year in 2007. Upper tropospheric air samples provide evidence for a continuing growth until late 2009. Furthermore we calculated a stratospheric lifetime of 370 years from measurements of air samples collected on board high altitude aircraft and balloons. Emission estimates were determined from the reconstructed atmospheric trend and suggest that current "bottom-up" estimates of global emissions for 2005 are too high by a factor of three

    Transient, unsettling and creative space: Experiences of liminality through the accounts of Chinese students on a UK-based MBA

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    This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ The Author(s) 2009.This article explores the experiences of liminality through the accounts of Chinese students on a UK-based MBA programme. The transient nature of the MBA experience, as well as the international status of the Chinese student, is resonant with conceptualizations of liminality as ‘in between’ space. Based on semi-structured interviews with 20 MBA graduates who had subsequently returned to China with their qualification, we explored their perceptions of outcomes from the course and their experiences as international students on a programme imbued with western norms and values. Results support the unsettling yet creative implications of liminality, as well as the fragmented insecure nature of identities, as individuals pass through the MBA ‘rite of passage’ in terms of ‘becoming’ a manager and entering a new phase of career. Accounts suggest the creation of hierarchical structures within liminal space whereby Chinese students, through their positioning at the margin, have uncomfortable yet illuminating encounters with alterity. At the same time, they experience levels of ambiguity and uncertainty in the post-liminal phase of China-located employments, as new western-based managerial identities collide with dominant discourses of Chinese organization

    Gene-based outcome prediction in multiple cohorts of pediatric T-cell acute lymphoblastic leukemia: a Children's Oncology Group study

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    <p>Abstract</p> <p>Background</p> <p>Continuous complete clinical remission in T-cell acute lymphoblastic leukemia (T-ALL) is now approaching 80% due to the implementation of aggressive chemotherapy protocols but patients that relapse continue to have a poor prognosis. Such patients could benefit from augmented therapy if their clinical outcome could be more accurately predicted at the time of diagnosis. Gene expression profiling offers the potential to identify additional prognostic markers but has had limited success in generating robust signatures that predict outcome across multiple patient cohorts. This study aimed to identify robust gene classifiers that could be used for the accurate prediction of relapse in independent cohorts and across different experimental platforms.</p> <p>Results</p> <p>Using HG-U133Plus2 microarrays we modeled a five-gene classifier (5-GC) that accurately predicted clinical outcome in a cohort of 50 T-ALL patients. The 5-GC was further tested against three independent cohorts of T-ALL patients, using either qRT-PCR or microarray gene expression, and could predict patients with significantly adverse clinical outcome in each. The 5-GC featured the interleukin-7 receptor (<it>IL-7R</it>), low-expression of which was independently predictive of relapse in T-ALL patients. In T-ALL cell lines, low <it>IL-7R </it>expression was correlated with diminished growth response to IL-7 and enhanced glucocorticoid resistance. Analysis of biological pathways identified the NF-κB and Wnt pathways, and the cell adhesion receptor family (particularly integrins) as being predictive of relapse. Outcome modeling using genes from these pathways identified patients with significantly worse relapse-free survival in each T-ALL cohort.</p> <p>Conclusions</p> <p>We have used two different approaches to identify, for the first time, robust gene signatures that can successfully discriminate relapse and CCR patients at the time of diagnosis across multiple patient cohorts and platforms. Such genes and pathways represent markers for improved patient risk stratification and potential targets for novel T-ALL therapies.</p

    A Generalization of Otsu's Method and Minimum Error Thresholding

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    We present Generalized Histogram Thresholding (GHT), a simple, fast, and effective technique for histogram-based image thresholding. GHT works by performing approximate maximum a posteriori estimation of a mixture of Gaussians with appropriate priors. We demonstrate that GHT subsumes three classic thresholding techniques as special cases: Otsu's method, Minimum Error Thresholding (MET), and weighted percentile thresholding. GHT thereby enables the continuous interpolation between those three algorithms, which allows thresholding accuracy to be improved significantly. GHT also provides a clarifying interpretation of the common practice of coarsening a histogram's bin width during thresholding. We show that GHT outperforms or matches the performance of all algorithms on a recent challenge for handwritten document image binarization (including deep neural networks trained to produce per-pixel binarizations), and can be implemented in a dozen lines of code or as a trivial modification to Otsu's method or MET.Comment: ECCV 202
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