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This study examines coordinated storm and triggered lightning observations made in July–August 2013 at the International Center for Lightning Research and Testing to determine why triggered flashes in Florida typically transition from an upward vertical channel entering the cloud to horizontal structure near the storm's melting level. Data from a balloon-borne electric field meter, a mobile 5 cm wavelength radar, and a small-baseline VHF Lightning Mapping Array acquired during a period in which three flashes were triggered on 1 August confirmed the hypothesis that the transition to horizontal lightning structure just above the melting level occurred in a layer of negative charge. This experiment was the first to provide vertical profiles of the electric field in Florida storms, from which their vertical charge distribution could be inferred. Three dissipating storms observed on different days all had negative charge near the melting level, but a growing mature storm had positive charge there.

In Recommendation ITU-R P.1853-1, a stochastic approach is proposed to generate long-term rain attenuation time series , including rain and no rain periods anywhere in the world. Nevertheless, its dynamic properties have been validated so far from experimental rain attenuation time series collected at mid-latitudes only. In the present paper, an effort is conducted to derive analytically the first- and second-order statistical properties of the ITU rain attenuation time-series synthesizer. It is then shown that the ITU synthesizer does not reproduce the first-order statistics (particularly the rain attenuation cumulative distribution function CDF), however, given as input parameters. It also prevents any rain attenuation correlation function other than exponential to be reproduced, which could be penalizing if a worldwide synthesizer that accounts for the local climatology has to be defined. Therefore, a new rain attenuation time-series synthesizer is proposed. It assumes a mixed Dirac-lognormal modeling of the absolute rain attenuation CDF and relies on a stochastic generation in the Fourier plane. It is then shown analytically that the new synthesizer reproduces much better the first-order statistics given as input parameters and enables any rain attenuation correlation function to be reproduced. The ability of each synthesizer to reproduce absolute rain attenuation CDFs given by Recommendation ITU-R P.618 is finally compared on a worldwide basis. It is then concluded that the new rain attenuation time-series synthesizer reproduces the rain attenuation CDF much better, preserves the rain attenuation dynamics of the current ITU synthesizer for simulations at mid-latitudes, and, if it proves to be necessary for worldwide applications, is able to reproduce any rain attenuation correlation function.

The main objective of the ESA ARTES 5.1 Contract 20887/07/NL/LvH "Verification of Propagation Impairment Mitigation Techniques" with Politecnico di Milano as Prime, ONERA and Space Engineering as subcontractors, was to validate the channel models and related input data appropriate for the design, analysis and/or control phase of Propagation Impairments Mitigation Techniques (PIMTs), both for the Broadcasting Satellite Service (BSS) and the Interactive Multimedia Broadband Service (IMMBS). For the BSS scenario, which is the focus of this paper, the On Board Antenna Pattern Reconfiguration (OBAPR) PIMT is investigated, using as channel models the rain field generators able to provide the spatial distribution of rain across the service area on the basis of large-scale meteorological forecasts. Their performance were tested using either radar data or a large dataset of beacon measurements collected in Europe during the OLYMPUS experiment.

To insure a favourable link budget in order to reach the required availabilities and to counteract severe propagation impairments, Fade Mitigation Techniques FMT, such as adaptive coding [8, 9] have to be implemented in the fixed satellites telecommunications systems. To develop, test and adjust the real-time algorithms of these adaptative FMTs, a good knowledge of the dynamics of the propagation channel is required and realistic attenuation time series are needed to feed system simulators. Unfortunately, the low number of available propagation experiments at Ka-band and above unavoidably leads to the use of channel models allowing synthetic total attenuation time series to be generated. The aim of this paper is first of all to present the justification of the parameterization used in Recommendation ITU-R P.1853--1 which has not been published in the open literature. Secondly, some limitations are highlighted before moving on an overview of a more simplified new channel model to synthesize total attenuation time series.

Multipaths are one of the major sources of errors for satellite navigation systems. The goal of this article is to present some advances on propagation channel modelling for GNSS mobile users and to show how GNSS receiving algorithms are sensitive to the modelling of the channel. Two channel characteristics are analysed in the paper: the resolution of the environment level of detail, and the resolution of the channel, meaning the number of significant echoes in the tapped-delay line. Particular focus is made on mitigation techniques using antenna arrays to reject multipath. The influence of the channel model will be then interpreted considering three different types of GNSS receiver algorithms, namely conventional DLL/PLL, beam forming and SAGE/STAP algorithm.

To develop and test real-time fade mitigation techniques control algorithms, propagation time series are needed. An alternative to using real data collected from propagation experiments is to generate typical fading time-series making use of climatological characteristics as well as geometrical and radio-electrical parameters of the link. The objective of this paper is to present a rain attenuation time-series synthesizer and able to generate events on demand. The model is based on an enhanced version of the Maseng–Bakken stochastic model. In the first part of this paper, the basic principles of the enhanced Maseng–Bakken model are recalled and the parameterization of this channel model is discussed for temperate European climates. Then, the theoretical bases of the Lacoste–Carrie ‘event-on-demand’ model and its validation constitute the second part of this paper. The enhanced Maseng–Bakken model is fully stochastic, whereas the Lacoste-Carrie ‘event-on-demand’ one offers the possibility to command the maximum attenuation level and the duration of the synthesized event. Copyright © 2009 John Wiley & Sons, Ltd.

Study objective To determine the extent of intravenous (IV) antibiotic use for community-acquired pneumonia (CAP) in emergency departments, the practice patterns in seven emergency departments serving the adult residents of one Canadian city were observed. Methods An observational study of nonhospitalized adults diagnosed with CAP in seven emergency departments was conducted between November 15, 2000, and November 19, 2002. Data related to antibiotic treatment of CAP administered in the emergency department and patient-specific characteristics potentially predictive of IV treatment were collected. Results A total of 3512 subjects were identified, of which 4.9% received treatment with IV antibiotics. Cefuroxime and levofloxacin were the most commonly used IV agents, while orally-treated subjects primarily received a macrolide or levofloxacin. The proportion of subjects receiving IV antibiotics differed significantly among the seven sites: 1.4%–10.6% (p > 0.0001). Logistic regression identified a number of independent predictors of receipt of IV antibiotics including risk class, temperature, respiratory rate, study year, presence of vomiting, prior antibiotic treatment, and personal care home residence. However, these predictors did not explain intersite differences. Conclusion Only a small proportion of patients (4.9%) presenting to the emergency department with CAP received IV antibiotics. While patient demographics and severity indicators influenced the likelihood of receipt of IV antibiotics, considerable intersite variation existed, despite adjustment for such factors.

OBJECTIVE: Antibiotics are among the most commonly used classes of agents in community practice; yet, studies of antibiotic use in this setting are scarce. Data from developed countries suggest increasing use of newer broad-spectrum agents, which has implications for the development of antibiotic resistance as well as cost of therapy. In this study, we quantified changing patterns of antibiotic use in community practice in Manitoba, Canada, from 1995 to 1998. DESIGN: A descriptive, population-based study of antibiotic use in Manitoba was facilitated by the Drug Programs Information Network (DPIN) of Manitoba Health; a data management system responsible for recording details of prescriptions dispensed for all Manitoba residents. Antibiotic use data, defined as numbers of prescriptions dispensed, were extracted from the DPIN from January 1, 1995, to March 31, 1998. Antibiotic use is reported as prescriptions per 1000 persons per year (Rx/1000/Yr) based on quarterly use. RESULTS: Penicillins (48.3%), macrolides (16.0%), and sulfonamides (12.5%) accounted for 75% of total antibiotic use; total use decreased 19.1% between 1995 and 1998. Use of the four most commonly prescribed agents decreased over the study period (amoxicillin, −17.4%; erythromycin, −29.0%; trimethoprim/sulfamethoxazole, −18.7%; penicillins G and V, −19.2%). In contrast, use of newer and/or broad-spectrum agents increased (ciprofloxacin, 21.9%; cefuroxime, 30.7%; and azithromycin/clarithromycin, 29.5%). Use of second-line agents as a percentage of total antibiotic use increased from 14.4% to 19.3% between January 1995 and March 1998 (p < 0.001). CONCLUSIONS: Penicillins, macrolides, and sulfonamides accounted for 75% of antibiotic use. Total antibiotic use declined over the study period; however, use of newer, broad-spectrum agents increased while use of older, narrow-spectrum agents decreased.

The objective of this paper is to briefly present the statistical analysis of a new propagation experiment carried out by ONERA in Toulouse from the 19.7 GHz beacon of the Eutelsat Hot Bird 6 satellite. A beacon Earth station, a profiling radiometer and a rain gauge were deployed and 2 years of beacon data have been collected, processed and analysed. This paper presents the statistical results obtained in terms of Cumulative Distribution Functions of rain rate, beacon total attenuation and fade dynamics. Then, the rain attenuation time series channel model ITU-R P.1853 will be compared to the measurements.

This paper addresses the statistical modelling of MIMO-LMS fading channels. In the absence of accurate experimental results, a statistical model for the characterization of MIMO-LMS channels is proposed based on consolidation of available experimental results for SISO-LMS, SIMO-LMS and MISO-LMS as well as on their extrapolation to the MIMO-LMS and satellite diversity cases of interest.

This is the author’s post-print version of the article published in IEEE Transactions on Antennas and Propagation The article has been peer-reviewed, but does not include the publisher’s layout and page numbers. Reprinted with permission from IEEE. Access to the published version may require journal subscription: http://dx.doi.org/10.1109/TAP.2011.2173447 We present a novel physical-statistical, generative model for the land mobile satellite (LMS), dual polarized, multiple-input-multiple-output (MIMO) channel along tree sided roads. Said model is parameterized by means of a physical model based on the Multiple Scattering Theory (MST) which accounts for the signal attenuation and scattering by trees. Moreover, Finite-Difference Time-Domain (FDTD) electromagnetic computations were performed to characterize the scattering pattern of an isolated tree, and to calculate the MIMO shadowing correlation matrix required by the model, and not provided by MST. This modeling framework also encompasses the single-input-multiple-output (SIMO)/space diversity case. To illustrate the capabilities of the developed model, time series were generated and used in system performance calculations. The obtained results give an insight into the advantages of dual polarized MIMO and SIMO/space diversity techniques in these very frequent scenarios, and may help service providers in evaluating the technical feasibility of such systems.

A digital computer program generating a simulated neural network was used to construct a model which can show behaviour resembling human associative memory. The experimental network uses distributed storage, and, in this respect, its functional organisation resembles that suggested by reported observations of neuronal activity in the human temporal lobe during memory storage and recall. Inactivation of increasing numbers of randomly distributed network units simulated advancing cerebral atrophy. This caused progressive impairment of performance, resembling the gradual deterioration of memory function observed in chronic diffuse cerebral degeneration. Unit inactivation had similar effects on recall whether the same units were inactivated before or after learning. This differs from most relevant observations of amnesia resulting from diffuse cerebral disease. While the model may functionally resemble long-term information storage sites in the brain, other cerebral mechanisms participating in learning and remembering are also damaged by diffuse cerebral atrophy.

In tropical and equatorial areas, the terrestrial telecommunications infrastructure is less developed than in temperate regions and there is a strong need to implement satellite communication systems in the next few years. These systems have the advantage of serving wide regions with a short deployment time and the possibility to reach a large market size for economic profitability. For new consumer applications, C-band is unattractive because the deployment of new systems with small terminals is incompatible with the large antennas required to protect the existing systems.

Under-treatment of pain is frequently reported, especially among seniors, with chronic non-cancer pain most likely to be under-treated. Legislation regarding the prescribing/dispensing of opioid analgesics (including multiple prescription programs [MPP]) may impede access to needed analgesics.To describe access and intensity of use of analgesics among older Manitobans by health region.A cross-sectional study of non-Aboriginal non-institutionalized Manitoba residents over 65 years of age during April 1, 2002 to March 31, 2003 was conducted using the Pharmaceutical Claims data and the Cancer Registry from the province of Manitoba. Access to analgesics (users/1000/Yr) and intensity of use (using defined daily dose [DDD] methodology) were calculated for non-opioid analgesics, opioids, and multiple-prescription-program opioids [MPP-opioids]. Usage was categorized by age, gender, and stratified by cancer diagnosis. Age-sex standardized rates of prevalence and intensity are reported for the eleven health regions of Manitoba.Thirty-four percent of older Manitobans accessed analgesics during the study period. Female gender, increasing age, and a cancer diagnosis were associated with greater access and intensity of use of all classes of analgesics. Age-sex standardized access and intensity measures revealed the highest overall analgesic use in the most rural / remote regions of the province. However, these same regions had the lowest use of opioids, and MPP-opioids among residents lacking a cancer diagnosis.This population-based study of analgesic use suggests that there may be variations in use of opioids and other analgesics depending on an urban or rural residence. The impact of programs such as the MPP program requires further study to describe its impact on analgesic use.

To develop and test real time fade mitigation techniques control algorithms, propagation time series are needed. An alternative to using real data collected from propagation experiments is to generate typical fading time series making use of climatological characteristics as well as geometrical and radio-electrical parameters of the link. The aim of the study presented in this paper is to validate time-series synthesisers relying on an enhanced Maseng-Bakken model for temperate areas. In the first part of this paper, the basic principles of the Maseng-Baken model are recalled and the parameterisation of this channel model is discussed for temperate climates. Then, Ka band beacon data collected in European and in North-American areas are used: on the one hand to retrieve the input parameters of the channel models and on the other hand to test them with respect to long-term statistics. The results of this testing analysis constitute the second part of this paper.

Increasing use of broad-spectrum antibiotics in the community, including fluoroquinolones, has been reported, despite concerns for developing antibiotic resistant organisms. Community-acquired pneumonia (CAP) is commonly treated on an outpatient basis, and recent treatment guidelines suggest only a limited role for fluoroquinolones.To identify evolving trends in the outpatient treatment of CAP in adults, and to identify factors associated with receipt of a fluoroquinolone.Retrospective observational design using population-based administrative data. Initial outpatient treatment for subjects diagnosed with CAP between May 1996 and March 2002 was examined. Logistic regression was used to examine the influence of patient characteristics on the receipt of a fluoroquinolone.A total of 31,940 outpatients with CAP were identified. The proportion of patients receiving fluoroquinolones increased from 6.6% in 1996/97 to 25.2% in 2001/02. Over the course of the study, 158 (25.9%) of the 610 patients meeting the eligibility criteria for treatment with fluoroquinolones, according to treatment guidelines, received these agents. Of the 31,330 subjects who did not meet the eligibility criterion, 3,886 (12.4%) received a fluoroquinolone. Other variables that influenced the receipt of a fluoroquinolone included: age (for every 10-year increase) [OR=1.16 (1.14-1.19)], urban residence [OR=1.40 (1.30-1.51)], presentation to an emergency department [OR=0.80 (0.70-0.90)], high-level drug use (six or more different drugs in the previous year) [OR=1.50 (1.41-1.59)], and income-level (highest to lowest) [OR=1.20 (1.08-1.35)].The use of fluoroquinolones for the treatment of CAP is increasing. However less than 4% of the subjects receiving fluoroquinolones met eligibility requirements according to treatment guidelines. Initiatives to increase the uptake of treatment guidelines appear warranted.

Most use of antibacterials occurs in community practice; however, despite the widespread belief of inappropriate use and the resultant increase in antibacterial resistance, little data exist describing antibacterial use in this setting. A MEDLINE search of English-language articles was conducted for epidemiological studies assessing quantity, indication and appropriateness of antibacterial use in community practice. A 1983 study of international antibacterial use described considerable disparities in quantity of use between countries. Subsequent longitudinal studies from the US, Canada, Australia and the UK described changing patterns of antibacterial use. No increase in the total rate of antibacterial use was reported by any of the 4 countries; however, all countries reported increased use of newer and/or broad-spectrum agents (e.g. fluoroquinolones, amoxicillin-clavulanic acid, cephalosporins and new macrolides] coupled with decreased use of older and/or narrow-spectrum agents [e.g. phenoxymethylpenicillin (penicillin V), erythromycin, ampicillin and tetracycline). Most (approximately three-quarters) use of antibacterials was in the treatment of respiratory tract infections. Prescribing rates for respiratory tract infections of presumed viral aetiology (e.g. the common cold) ranged from 17 to 60% in the UK and US, respectively. Among indications for which antibacterials were indicated, the appropriateness of antibacterial use received little study. Correspondingly, the rates of antibacterial resistance among common respiratory pathogens (Streptococcus pneumoniae and Haemophilus influenzae) have increased significantly in the past decade, although disparities exist between countries. Antibacterial use is considered a major factor in the development of antibacterial resistance, although the relationship between community antibacterial use and resistance has been poorly described. Further study of antibacterial usage patterns and associated resistance patterns is fundamental to the development of methods to reduce unnecessary and inappropriate use, thereby slowing the development of antibacterial resistance in the community.

The physiological tremor occurring at the metacarpophalangeal joint of the index was observed during extension of this finger against a load of 50G. The tremor characteristics (1) during visual monitoring of a display of positional error, and (2) following eye closure, were studied in 22 anxious patients and a matched group of normal subjects. Harmonic analysis showed that the average tremor amplitude at each of 12 frequencies between 2 and 14 c/s was relatively larger in the patient group under both recording conditions. The pooled data from the control subjects showed a relatively smaller tremor amplitude at each frequency when the eyes were closed, with particularly marked attenuation at 8-10 c/s. Fourteen of the patients showed a relatively increased tremor amplitude after eye closure at 6 or more of the 12 frequencies studied when compared with the amplitudes observed when they were monitoring the visual display of performance. This pattern was seen in only 3 subjects in the control series. This type of response to eye closure was significantly more common in the series of patients than in the control group.

The tremor occurring at the metacarpophalangeal joint of the index finger during a motor task involving a controlled muscle effort was detected and measured. The subjects were required to maintain the finger as accurately as possible in a constant alignment against a 50-gm. load with the aid of an amplified visual display of the position of the finger. The tremor displayed by 18 morbidly anxious male patients was compared with that occurring in a matched group of 18 male control subjects. The tremor of the anxious patients differed from that of the controls in that (1) it was of greater average amplitude, and (2) the 7-10 c/sec. components were relatively more prominent than other components in the 4-12 c/sec. range. Both of these differences were found to be statistically significant. The proportional reduction in tremor amplitude observed in the 4-12 c/sec. range during repeated performance of the task did not differ significantly in the anxious patients as compared with the controls. The relevance of these findings to other investigations of habituation of physiological variables in psychiatric patients is considered.