Computing the output distribution and selection probabilities of a stack filter from the DNF of its positive Boolean function

Many nonlinear filters used in practise are stack filters. An algorithm is presented which calculates the output distribution of an arbitrary stack filter S from the disjunctive normal form (DNF) of its underlying positive Boolean function. The so called selection probabilities can be computed along the way.Comment: This is the version published in Journal of Mathematical Imaging and Vision, online first, 1 august 201

HASH(0x563d43f9e480)

HASH(0x563d43f23d80

How sensitive is tropospheric oxidation to anthropogenic emissions?

We use a global chemistry transport model to explore how changes in anthropogenic emissions alter ozone production and tropospheric oxidizing capacity over decadal (1990–2010) and centennial timescales (1900–2100). We find that the spatial extent of O3 production and loss in the troposphere changes very little despite large projected increases in precursor emissions. While tropospheric OH shows a long-term decrease of only 20% between 1900 and 2100, there are widespread changes in distribution which alter regional oxidation capacity substantially. We show that the remote marine boundary layer remains an important net sink of O3, as greater production related to increased continental NO x emissions is outweighed by greater O3 destruction. The critical NO x level required to support net O3 production doubles between 1900 and 2100, from 28 to 55 pptv on average, preventing any large-scale shift in production regime

Part-time work and other occupational risk factors for suicide among working women in the Swiss National Cohort.

The aim of this study was to describe the factors associated with mortality by suicide among working women focusing on work-related factors. The study population consisted in all Swiss residents recorded in the 1990 and/or the 2000 compulsory national censuses and were linked to emigration and mortality registers. We selected all women aged 18-65 and at work at the official census dates. Following work-related variables were available: socio-economic status, weekly hours of work, the sector of activity and the job title coded according to the International Standard Classification of Occupations (ISCO). The risk of suicide was modelled using negative binomial regression. The cohort comprised 1,771,940 women and 2526 deaths by suicide corresponding to 24.9 million person-years. The most significant non-occupational predictors of suicide were age, period, civil status, religion, nationality and geographical regions. Adjusted on these factors, part-time work was associated with increased suicide rates. According to job codes, health and social activities, in particular care-worker had the highest suicide risks. Suicide among working women depended on work-related factors even taking into account other socio-demographic factors

Evaluation of High Impedance Surfaces for MRI RF Coil Applications ­ Simulations of RF Field and Specific Absorption Rate

This paper investigates the use of High Impedance Surfaces (HIS) to enhance the magnetic near-field within a dielectric phantom stimulated by a surface coil antenna resonating at 63.8 MHz for use in Magnetic Resonance Imaging (MRI) systems. Specifically, the optimization of the space between the surface of the coil and the HIS is presented here. The HIS incorporates interdigitated capacitive elements that produce an electrically small unit cell size. The magnetic field strength is shown to be improved by 42% as compared to a system which uses only an RF shield The associated Specific Absorption Rate (SAR) for the optimum design is simulated and compared to international standards. The work is aimed at 1.5T MRI applications

Chemical transport model ozone simulations for spring 2001 over the western Pacific:comparisons with TRACE-P lidar, ozonesondes, and Total Ozone Mapping Spectrometer columns

Two closely related chemical transport models (CTMs) employing the same high-resolution meteorological data (similar to180 km x similar to180 km x similar to600 m) from the European Centre for Medium-Range Weather Forecasts are used to simulate the ozone total column and tropospheric distribution over the western Pacific region that was explored by the NASA Transport and Chemical Evolution over the Pacific (TRACE-P) measurement campaign in February-April 2001. We make extensive comparisons with ozone measurements from the lidar instrument on the NASA DC-8, with ozonesondes taken during the period around the Pacific Rim, and with TOMS total column ozone. These demonstrate that within the uncertainties of the meteorological data and the constraints of model resolution, the two CTMs (FRSGC/UCI and Oslo CTM2) can simulate the observed tropospheric ozone and do particularly well when realistic stratospheric ozone photochemistry is included. The greatest differences between the models and observations occur in the polluted boundary layer, where problems related to the simplified chemical mechanism and inadequate horizontal resolution are likely to have caused the net overestimation of about 10 ppb mole fraction. In the upper troposphere, the large variability driven by stratospheric intrusions makes agreement very sensitive to the timing of meteorological features

A magnetic resonance imaging surface coil transceiver employing a metasurface for 1.5T applications

A capacitive impedance metasurface combined with a transceiver coil to improve the radio frequency magnetic field for 1.5T magnetic resonance imaging applications is presented. The novel transceiver provides localized enhancement in magnetic flux density when compared to a transceiver coil alone by incorporating an electrically small metasurface using an interdigital capacitance approach. Full field simulations employing the metasurface show a significant improvement in magnetic flux density inside a homogeneous dielectric phantom, which is also shown to perform well for a range of depths into the phantom. The concept was experimentally demonstrated through vector network analyzer measurements and images have been taken using a 1.5T MRI scanner. The results show there is a 216% improvement in transmission efficiency, a 133% improvement in receiver signal-to-noise-ratio (SNR), and a 415% improvement in transceiver SNR for a particular transmission power when compared against a surface coil positioned at the same distance from the phantom, where these improvements are the maximum observed during experiments

Yukawa Textures and the mu-term

We show how with an anomaly-free U(1), simple assumptions concerning the origin of Yukawa textures and the Higgs mu-term lead to the prediction of a new physics scale of 10^8GeV and automatic conservation of baryon number.Comment: 12 pages, uses Harvmac (option "b"

Mesoscale observations of Joule heating near an auroral arc and ion-neutral collision frequency in the polar cap E region

We report on the first mesoscale combined ionospheric and thermospheric observations, partly in the vicinity of an auroral arc, from Svalbard in the polar cap on 2 February 2010. The EISCAT Svalbard radar employed a novel scanning mode in order to obtain F and E region ion flows over an annular region centered on the radar. Simultaneously, a colocated Scanning Doppler Imager observed the E region neutral winds and temperatures around 110 km altitude using the 557.7 nm auroral optical emission. Combining the ion and neutral data permits the E region Joule heating to be estimated with an azimuthal spatial resolution of ∼64 km at a radius of ∼163 km from the radar. The spatial distribution of Joule heating shows significant mesoscale variation. The ion-neutral collision frequency is measured in the E region by combining all the data over the entire field of view with only weak aurora present. The estimated ion-neutral collision frequency at ∼113 km altitude is in good agreement with the MSIS atmospheric model

Quantum Hall Resistance Overshoot in 2-Dimensional Electron Gases - Theory and Experiment

We present a systematical experimental investigation of an unusual transport phenomenon observed in two dimensional electron gases in Si/SiGe heterostructures under integer quantum Hall effect (IQHE) conditions. This phenomenon emerges under specific experimental conditions and in different material systems. It is commonly referred to as Hall resistance overshoot, however, lacks a consistent explanation so far. Based on our experimental findings we are able to develop a model that accounts for all of our observations in the framework of a screening theory for the IQHE. Within this model the origin of the overshoot is attributed to a transport regime where current is confined to co-existing evanescent incompressible strips of different filling factors.Comment: 26 pages, 10 figure