565 research outputs found
Online Gaming Can Make a Better World: Jane McGonigal
With personal feelings put aside and sociological theoretical depictions brought to the forefront, it is interesting to compare some of Jane\u27s ideas with that of both Emile Durkheim and Max Weber. The theorist who stood out right away, being exemplified through Jane\u27s positive attitude claims on a much larger, macro-level scale, was Emile Durkheim. Jane\u27s ideas about transcending human\u27s as a resource through the social fabrics of gaming into something that might solve world hunger, poverty, and global warming was nothing short of functionalism at it\u27s best. Jane\u27s platform for social structure and maintaining positive social order is the online world, and online gaming is the vehicle for change
Optimal Concentration of Information Content For Log-Concave Densities
An elementary proof is provided of sharp bounds for the varentropy of random
vectors with log-concave densities, as well as for deviations of the
information content from its mean. These bounds significantly improve on the
bounds obtained by Bobkov and Madiman ({\it Ann. Probab.}, 39(4):1528--1543,
2011).Comment: 15 pages. Changes in v2: Remark 2.5 (due to C. Saroglou) added with
more general sufficient conditions for equality in Theorem 2.3. Also some
minor corrections and added reference
Postglacial fluctuations of Cordillera Darwin glaciers (southernmost Patagonia) reconstructed from Almirantazgo fjord sediments
Author Posting. © The Author(s), 2017. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Quaternary Science Reviews 177 (2017):265-275, doi:10.1016/j.quascirev.2017.10.029.Most outlet glaciers of the Cordillera Darwin Icefield (CDI; Patagonia, 54â°S) are currently transitioning from calving to land-based conditions. Whether this situation is unique to the modern climate or also occurred during the Holocene is entirely unknown. Here, we investigate the Holocene fluctuations of outlet glaciers from the northern flank of the CDI using a multi-proxy sedimentological and geochemical analysis of a 13.5 m long sediment core from Almirantazgo fjord. Our results demonstrate that sedimentation in Almirantazgo fjord started prior to 14,300 cal yr BP, with glacier-proximal deposits occurring until 13,500 cal yr BP. After 12,300 cal yr BP, most glaciers had retreated to land-locked locations and by 9800 cal yr BP, Almirantazgo fjord was a predominantly marine fjord environment with oceanographic conditions resembling the present-day setting. Our sediment record shows that during the first part of the Holocene, CDI glaciers were almost entirely land-based, with a possible re-advance at 7300â5700 cal yr BP. This is in clear contrast with the Neoglaciation, during which CDI glaciers rapidly re-advanced and shrank back several times, mostly in phase with the outlet glaciers of the Southern Patagonian Icefield (SPI). Two significant meltwater events, indicative of rapid glacier retreat, were identified at 3250â2700 and 2000â1200 cal yr BP, based on an increase in grain-size mode and related inorganic geochemical parameters. This interpretation is additionally supported by concomitant decreases in organic carbon of marine origin and in Cl counts (salinity), reflecting higher terrestrial input to the fjord and freshening of the fjord waters. Overall, our record suggests that CDI outlet glaciers advanced in phase with SPI glaciers during the Neoglaciation, and retreated far enough into their valleys twice to form large outwash plains. Our results also highlight the potential of fjord sediments to reconstruct glacier variability at high resolution on multi-millennial timescales.This research was supported by an EU Marie Curie FP6 postdoctoral fellowship to S.B., by National Geographic Grant 8379-07 (to S.B.), by COPAS Center FONDAP Grant 150100007 and COPAS Sur-Austral CONICYT PIA PFB31 (to C.L and S.P), and by IDEAL Center FONDAP Grant 15150003 (to C.L.)
Pore fluid modeling approach to identify recent meltwater signals on the west Antarctic Peninsula
The sensitivity of sea level to melting from polar ice sheets and glaciers during recent natural and
anthropogenic climate fluctuations is poorly constrained beyond the period of direct observation by satellite.
We have investigated glacial meltwater events during the Anthropocene by adapting the pioneering
approach of modeling trends in d18O in the pore waters of deepâsea cores, previously used to constrain
the size of ice sheets during the Last Glacial Maximum. We show that during recent warm periods, meltwater
from glacier retreat drains into the coastal fjords, leaving a signature of depleted d18O values and low
Cl concentrations in the pore water profiles of rapidly accumulating sediments. Here we model such pore
water profiles in a piston core to constrain the timing and magnitude of an ice sheet retreat event at Caley
Glacier on the west Antarctic Peninsula, and the result is compared with local ice front movement. This
approach of pore water modeling was then applied in another kasten core and tested by a series of sensitivity
analyses. The results suggest that our approach may be applied in fjords of different sedimentary settings
to reconstruct the glacier history and allow insight into the sensitivity of polar glaciers to abrupt
warming events
Inconsistency of the MLE for the joint distribution of interval censored survival times and continuous marks
This paper considers the nonparametric maximum likelihood estimator (MLE) for
the joint distribution function of an interval censored survival time and a
continuous mark variable. We provide a new explicit formula for the MLE in this
problem. We use this formula and the mark specific cumulative hazard function
of Huang and Louis (1998) to obtain the almost sure limit of the MLE. This
result leads to necessary and sufficient conditions for consistency of the MLE
which imply that the MLE is inconsistent in general. We show that the
inconsistency can be repaired by discretizing the marks. Our theoretical
results are supported by simulations.Comment: 27 pages, 4 figure
A Comprehensive Molecular Characterization of the Pancreatic Neuroendocrine Tumor Cell Lines BON-1 and QGP-1
Experimental models of neuroendocrine tumor disease are scarce, with only a few existing neuroendocrine tumor cell lines of pancreatic origin (panNET). Their molecular characterization has so far focused on the neuroendocrine phenotype and cancer-related mutations, while a transcription-based assessment of their developmental origin and malignant potential is lacking. In this study, we performed immunoblotting and qPCR analysis of neuroendocrine, epithelial, developmental endocrine-related genes as well as next-generation sequencing (NGS) analysis of microRNAs (miRs) on three panNET cell lines, BON-1, QGP-1, and NT-3. All three lines displayed a neuroendocrine and epithelial phenotype; however, while insulinoma-derived NT-3 cells preferentially expressed markers of mature functional pancreatic ÎČ-cells (i.e., INS, MAFA), both BON-1 and QGP-1 displayed high expression of genes associated with immature or non-functional ÎČ/ÎŽ-cells genes (i.e., NEUROG3), or pancreatic endocrine progenitors (i.e., FOXA2). NGS-based identification of miRs in BON-1 and QGP-1 cells revealed the presence of all six members of the miR-17-92 cluster, which have been implicated in b-cell function and differentiation, but also have roles in cancer being both oncogenic or tumor suppressive. Notably, both BON-1 and QGP-1 cells expressed several miRs known to be negatively associated with epithelial-mesenchymal transition, invasion or metastasis. Moreover, both cell lines failed to exhibit migratory activity in vitro. Taken together, NT-3 cells resemble mature functional ÎČ-cells, while both BON-1 and QGP-1 are more similar to immature/non-functional pancreatic ÎČ/ÎŽ-cells or pancreatic endocrine progenitors. Based on the recent identification of three transcriptional subtypes in panNETs, NT-3 cells resemble the "islet/insulinoma tumors" (IT) subtype, while BON-1 and QGP-1 cells were tentatively classified as "metastasis-like/primary" (MLP). Our results provide a comprehensive characterization of three panNET cell lines and demonstrate their relevance as neuroendocrine tumor models
A specific case in the classification of woods by FTIR and chemometric: discrimination of Fagales from Malpighiales
Fourier transform infrared (FTIR) spectroscopic data was used to classify wood samples from nine species within the Fagales and Malpighiales using a range of multivariate statistical methods. Taxonomic classification of the family Fagaceae and Betulaceae from Angiosperm Phylogenetic System Classification (APG II System) was successfully performed using supervised pattern recognition techniques. A methodology for wood sample discrimination was developed using both sapwood and heartwood samples. Ten and eight biomarkers emerged from the dataset to discriminate order and family, respectively. In the species studied FTIR in combination with multivariate analysis highlighted significant chemical differences in hemicelluloses, cellulose and guaiacyl (lignin) and shows promise as a suitable approach for wood sample classification
Transatlantic registries of pancreatic surgery in the United States of America, Germany, the Netherlands, and Sweden: Comparing design, variables, patients, treatment strategies, and outcomes
Background: Registries of pancreatic surgery have become increasingly popular as they facilitate both quality improvement and clinical research. We aimed to compare registries for design, variables collected, patient characteristics, treatment strategies, clinical outcomes, and pathology. Methods: Registered variables and outcomes of pancreatoduodenectomy (2014â2017) in 4 nationwide or multicenter pancreatic surgery registries from the United States of America (American College of Surgeons National Surgical Quality Improvement Program), Germany (Deutsche Gesellschaft fĂŒr Allgemein- und Viszeralchirurgie - Studien-, Dokumentations- und QualitĂ€tszentrum), the Netherlands (Dutch Pancreatic Cancer Audit), and Sweden (Swedish National Pancreatic and Periampullary Cancer Registry) were compared. A core registry set of 55 parameters was identified and evaluated using relative and absolute largest differences between extremes (smallest versus largest). Results: Overall, 22,983 pancreatoduodenectomies were included (15,224, 3,558, 2,795, and 1,406 in the United States of America, Germany, the Netherlands, and Sweden). Design of the registries varied because 20 out of 55 (36.4%) core parameters were not available in 1 or more registries. Preoperative chemotherapy in patients with pancreatic ductal adenocarcinoma was administered in 27.6%, 4.9%, 7.0%, and 3.4% (relative largest difference 8.1, absolute largest difference 24.2%, P < .001). Minimally invasive surgery was performed in 7.8%, 4.5%, 13.5%, and unknown (relative largest difference 3.0, absolute largest difference 9.0%, P < .001). Median length of stay was 8.0, 16.0, 12.0, and 11.0 days (relative largest difference 2.0, absolute largest difference 8.0, P < .001). Reoperation was performed in 5.7%, 17.1%, 8.7%, and 11.2% (relative largest difference 3.0, absolute largest difference 11.4%, P < .001). In-hospital mortality was 1.3%, 4.7%, 3.6%, and 2.7% (relative largest difference 3.6, absolute largest difference 3.4%, P < .001). Conclusion: Considerable differences exist in the design, variables, patients, treatment strategies, and outcomes in 4 Western registries of pancreatic surgery. The absolute largest differences of 24.3% for the use of preoperative chemotherapy, 9.0% for minimally invasive surgery, 11.4% for reoperation rate, and 3.4% for in-hospital mortality require further study and improvement. This analysis provides 55 core parameters for pancreatic surgery registries
Supersymmetry and Integrability in Planar Mechanical Systems
We present an N=2-supersymmetric mechanical system whose bosonic sector, with
two degrees of freedom, stems from the reduction of an SU(2) Yang-Mills theory
with the assumption of spatially homogeneous field configurations and a
particular ansatz imposed on the gauge potentials in the dimensional reduction
procedure. The Painleve test is adopted to discuss integrability and we focus
on the role of supersymmetry and parity invariance in two space dimensions for
the attainment of integrable or chaotic models. Our conclusion is that the
relationships among the parameters imposed by supersymmetry seem to drastically
reduce the number of possibilities for integrable interaction potentials of the
mechanical system under consideration.Comment: 20 pages, 3 figure
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