1,617 research outputs found
Comparison of high-latitude line-of-sight ozone column density with derived ozone fields and the effects of horizontal inhomogeneity
International audienceExtensive ozone measurements were made during the second SAGE III Ozone Loss and Validation Experiment (SOLVE II). We compare high-latitude line-of-sight (LOS) slant column ozone measurements from the NASA DC-8 to ozone simulated by forward integration of measurement-derived ozone fields constructed both with and without the assumption of horizontal homogeneity. The average bias and rms error of the simulations assuming homogeneity are relatively small (?6 and 10%, respectively) in comparison to the LOS measurements. The comparison improves significantly (?2% bias; 8% rms error) using forward integrations of three-dimensional proxy ozone fields reconstructed from potential vorticity-O3 correlations. The comparisons provide additional verification of the proxy fields and quantify the influence of large-scale ozone inhomogeneity. The spatial inhomogeneity of the atmosphere is a source of error in the retrieval of trace gas vertical profiles and column abundance from LOS measurements, as well as a complicating factor in intercomparisons that include LOS measurements at large solar zenith angles
A Formalization of the Theorem of Existence of First-Order Most General Unifiers
This work presents a formalization of the theorem of existence of most
general unifiers in first-order signatures in the higher-order proof assistant
PVS. The distinguishing feature of this formalization is that it remains close
to the textbook proofs that are based on proving the correctness of the
well-known Robinson's first-order unification algorithm. The formalization was
applied inside a PVS development for term rewriting systems that provides a
complete formalization of the Knuth-Bendix Critical Pair theorem, among other
relevant theorems of the theory of rewriting. In addition, the formalization
methodology has been proved of practical use in order to verify the correctness
of unification algorithms in the style of the original Robinson's unification
algorithm.Comment: In Proceedings LSFA 2011, arXiv:1203.542
Recommended from our members
Prenatal Vitamin Use and Vitamin D Status during Pregnancy, Differences by Race and Overweight Status
Objective: We aimed to study whether prenatal vitamin (PNV) use protects against low 25(OH)D levels in all women and particularly in obese and black women who are both at risk of vitamin D deficiency and poor pregnancy outcomes. Study design We studied 1019 women enrolled in a prospective study at Brigham and Women’s Hospital in Boston, 2007–2009. We used multivariable logistic regression to analyze associations of PNV use and odds of vitamin D deficiency defined as 25(OH)D levels < 50 nmol/L. Results: 56% of black and 86% of white women reported pre- and/or post-conceptional PNV use. 75% of black and 19% of white women were vitamin D deficient in the first trimester. PNV use among black women was not associated with vitamin D deficiency (adjusted OR 1.0, 95%CI 0.4, 2.3) but was among white women (3.5, 95%CI 2.1, 5.8)(Interaction P<0.01). Conclusions: Ongoing trials of vitamin D supplementation during pregnancy should consider potential effect modification by race/ethnicity
Emerging Strategies for Healthy Urban Governance
Urban health promotion is not simply a matter of the right interventions, or even the necessary resources. Urban (and indeed global) health depends to an important extent on governance, the institutions and processes through which societies manage the course of events. This paper describes the concept of governance, distinguishing between reforms aimed at improving how government works and innovations that more fundamentally reinvent governance by developing new institutions and processes of local stakeholder control. The paper highlights strategies urban governors can use to maximize their influence on the national and international decisions that structure urban life. It concludes with some observations on the limitations of local governance strategies and the importance of establishing a “virtuous circuit” of governance through which urban dwellers play a greater role in the formation and implementation of policy at the national and global levels
Discovery of Dust Emission Activity Emanating from Main-belt Asteroid 2015 FW412
We present the discovery of activity emanating from main-belt asteroid 2015
FW412, a finding stemming from the Citizen Science project Active Asteroids, a
NASA Partner program. We identified a pronounced tail originating from 2015
FW412 and oriented in the anti-motion direction in archival Blanco 4-m (Cerro
Tololo Inter-American Observatory, Chile) Dark Energy Camera (DECam) images
from UT 2015 April 13, 18, 19, 21 and 22. Activity occurred near perihelion,
consistent with the main-belt comets (MBCs), an active asteroid subset known
for sublimation-driven activity in the main asteroid belt; thus 2015 FW412 is a
candidate MBC. We did not detect activity on UT 2021 December 12 using the
Inamori-Magellan Areal Camera and Spectrograph (IMACS) on the 6.5 m Baade
telescope, when 2015 FW412 was near aphelion.Comment: 4 pages, 1 figur
Prognostic and therapeutic significance of carbohydrate antigen 19-9 as tumor marker in patients with pancreatic cancer
In pancreatic cancer ( PC) accurate determination of treatment response by imaging often remains difficult. Various efforts have been undertaken to investigate new factors which may serve as more appropriate surrogate parameters of treatment efficacy. This review focuses on the role of carbohydrate antigen 19- 9 ( CA 19- 9) as a prognostic tumor marker in PC and summarizes its contribution to monitoring treatment efficacy. We undertook a Medline/ PubMed literature search to identify relevant trials that had analyzed the prognostic impact of CA 19- 9 in patients treated with surgery, chemoradiotherapy and chemotherapy for PC. Additionally, relevant abstract publications from scientific meetings were included. In advanced PC, pretreatment CA 19- 9 levels have a prognostic impact regarding overall survival. Also a CA 19- 9 decline under chemotherapy can provide prognostic information for median survival. A 20% reduction of CA 19- 9 baseline levels within the first 8 weeks of chemotherapy appears to be sufficient to define a prognostic relevant subgroup of patients ('CA 19- 9 responder'). It still remains to be defined whether the CA 19- 9 response is a more reliable method for evaluating treatment efficacy compared to conventional imaging. Copyright (c) 2006 S. Karger AG, Basel
- …