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modelling the impact of antibiotic use on antibiotic-resistant Escherichia coli using population-based data from a large hospital and its surrounding community

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JOURNAL OF ANTIMICROBIAL CHEMOTHERAPY 2011年第4期66卷 928-935页

作者： Vernaz, Nathalie Huttner, Benedikt Muscionico, Daniel Salomon, Jean-Luc Bonnabry, Pascal Maria Lopez-Lozano, Jose Beyaert, Arielle Schrenzel, Jacques Harbarth, Stephan Univ Hosp Geneva Dept Pharm Geneva Switzerland Univ Geneva Sch Med CH-1211 Geneva Switzerland Univ Hosp Geneva Infect Control Program Geneva Switzerland Invoice Off OFAC Geneva Switzerland Hosp Vega Baja Invest Unit Alicante Spain Univ Murcia Dept Quantitat Methods Econ & Business Murcia Spain Univ Hosp Geneva Clin Microbiol Lab Geneva Switzerland

Objectives: To determine the temporal relationship between antibiotic use and incidence of antibiotic-resistant Escherichia coli in both the inpatient and outpatient setting of a large urban area. Methods: A retrospective observational time-series analysis was performed to evaluate the incidence of non-duplicate clinical isolates of E. coli resistant to ciprofloxacin, trimethoprim/sulfamethoxazole and cefepime from January 2000 through December 2007, combined with a transfer function model of aggregated data on antibiotic use in both settings obtained from the hospital's pharmacy and outpatient billing offices. Results: Ciprofloxacin resistance increased from 6.0% (2000) to 15.4% (2007;P < 0.0001) and cefepime resistance from 0.9% (2002) to 3.2% (2007;P = 0.01). Trimethoprim/sulfamethoxazole resistance remained stable (23.7%-25.8%). Total antibiotic use increased in both settings, while fluoroquinolone use increased significantly only among outpatients. A temporal effect between fluoroquinolone resistance in community E. coli isolates and outpatient use of ciprofloxacin (immediate effect and time lag 1 month) and moxifloxacin (time lag 4 months) was observed, explaining 51% of the variance over time. The incidence of cefepime resistance in E. coli was correlated with ciprofloxacin use in the inpatient (lag 1 month) and outpatient (lag 4 months) settings and with the use of ceftriaxone (lag 0 month), piperacillin/tazobactam (3 months) and cefepime (3 months) in the hospital (R-2 = 51%). Conclusions: These results support efforts to reduce prescribing of fluoroquinolones for control of resistant E. coli including extended-spectrum beta-lactamase producers and show the added value of time-series analysis to better understand the interaction between community and hospital antibiotic prescribing and its spill-over effect on antibiotic resistance.

关键词： antibiotic resistance E. coli fluoroquinolone resistance extended-spectrum beta-lactamase-producing bacteria transfer function model health policy making time-series analysis

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Hydrologic and Ecological Effects of Watershed Urbanization: Implication for Watershed Management in Hillslope Regions

Hydrologic and Ecological Effects of Watershed Urbanization:...

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作者： Sung, Chan Yong Texas A&M University

In this study, I examined the effect of watershed urbanization on the invasion of alien woody species in riparian forests. This study was conducted in three major steps: 1) estimating the degree of watershed urbanization using impervious surface maps extracted from remote sensing images; 2) examining the effect of urbanization on hydrologic regime; and 3) investigating a relationship between watershed urbanization and ecosystem invasibility of a riparian forest. I studied twelve riparian forests along urban-rural gradients in Austin, Texas. Hydrologic regimes were quantified by transfer function (TF) models using four-year daily rainfall-streamflow data in two study periods (10/1988-09/1992 and 10/2004-09/2008) between which Austin had experienced rapid urbanization. For each study period, an impervious surface map was generated from Landsat TM image by a support vector machine (SVM) with pairwise coupling. SVM more accurately estimated impervious surface than other subpixel mapping methods. Ecosystem invasibilities were assessed by relative alien cover (RAC) of riparian woody species communities. The results showed that the effects of urbanization differ by hydrogeologic conditions. Of the study watersheds, seven located in a hillslope region experienced the diminishing peakflows between the two study periods, which are contrary to current urban hydrologic model. I attributed the decreased peakflows to land grading that transformed a hillslope into a stair-stepped landscape. In the rest of the watersheds, peakflow diminished between the two study periods perhaps due to the decrease in stormwater infiltration and groundwater pumpage that lowered groundwater level. In both types of watersheds, streamflow rising during a storm event more quickly receded as watershed became more urbanized. This study found a positive relationship between RAC and watershed impervious surface percentage. RAC was also significantly related to flow recession and canopy gap percentages, bot

关键词： remote sensing subpixel mapping hillslope hydrology transfer function model hydrologic drought urban ecology biological invasion Thesis

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Wave height forecasting by the transfer function model

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OCEAN ENGINEERING 2006年第8-9期33卷 1230-1248页

作者： Ho, PC Yim, JZ Keelung Harbor Bur Dept Engn Chilung Taiwan Natl Taiwan Ocean Univ Dept Harbor & River Engn Chilung Taiwan

Three completing methods were introduced in this paper. The data were completed from 1983 to 1988 at the KL and PTC stations. The completed data were called original data. The completing methods were the transfer function with fixed-parameters then built the transfer function (TF) model between the two stations. The TF model was used to estimate the wave data of the future. The difference of the estimated data and the original data were conferred in this paper. Two types of forecasting differences were discussed here: (1) the input data year increases from 1 to 6 years, and the difference of the estimated data and the original data were then compared. (2) Use one-year data as the input series to forecast the data of the next five years, and then compare the differences of the estimated data and the original data. After comparing the differences we can know the results. The mean value and the standard deviation of the differences decrease and go more stable as the quantity of the input data year increases. The mean value and the standard deviation of the differences increase and go more unstable as the quantity of the forecasted data year increases. This model can be used to forecast the wave data. (C) 2005 Elsevier Ltd. All rights reserved.

关键词： forecast time series analysis ARMA model transfer function model

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Integration of transfer function model and back propagation neural network for forecasting storm sewer flow in Taipei metropolis

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STOCHASTIC ENVIRONMENTAL RESEARCH AND RISK ASSESSMENT 2006年第1-2期20卷 6-22页

作者： Lu, CC Chen, CH Yeh, TCJ Wu, CM Yau, IF Univ Arizona Dept Hydrol & Water Resources Tucson AZ 85721 USA ChungKuo Inst Technol Dept Int Trade Taipei Taiwan ChungKuo Inst Technol Dept Civil Engn Taipei Taiwan Natl Taiwan Univ Dept Civil Engn Taipei 10764 Taiwan

Typhoons and storms have often brought heavy rainfalls and induced floods that have frequently caused severe damage and loss of life in Taiwan. Our ability to predict sewer discharge and forecast floods in advance during storm seasons plays an important role in flood warning and flood hazard mitigation. In this paper, we develop an integrated model (TFMBPN) for forecasting sewer discharge that combines two traditional models: a transfer function model and a back propagation neural network. We evaluated the integrated model and the two traditional models by applying them to a sewer system of Taipei metropolis during three past typhoon events (NARI, SINLAKU, and NAKR). The performances of the models were evaluated by using predictions of a total of 6 h of sewer flow stages, and six different evaluation indices of the predictions. Finally, an overall performance index was determined to assess the overall performance of each model. Based on these evaluation indices, our analysis shows that TFMBNP yields accurate results that surpass the two traditional models. Thus, TFMBNP appears to be a promising tool for flood forecasting for the Taipei metropolis sewer system.

关键词： transfer function model back propagation neural network storm sewer flow evaluation indexes overall performance index

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Forecasting Pollen Concentration by a Two-Step functional model

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BIOMETRICS 2010年第2期66卷 578-585页

作者： Valderrama, Mariano J. Ocana, Francisco A. Aguilera, Ana M. Ocana-Peinado, Francisco M. Univ Granada Dept Stat E-18071 Granada Spain

A functional regression model to forecast the cypress pollen concentration during a given time interval, considering the air temperature in a previous interval as the input, is derived by means of a two-step procedure. This estimation is carried out by functional principal component (FPC) analysis and the residual noise is also modeled by FPC regression, taking as the explicative process the pollen concentration during the earlier interval. The prediction performance is then tested on pollen data series recorded in Granada (Spain) over a period of 10 years.

关键词： functional linear regression Karhunen-Loeve expansion Pollen concentration transfer function model

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Artificial neural network and time series models for predicting soil salt and water content

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AGRICULTURAL WATER MANAGEMENT 2010年第12期97卷 2009-2019页

作者： Zou, Ping Yang, Jingsong Fu, Jianrong Liu, Guangming Li, Dongshun Chinese Acad Sci Inst Soil Sci Nanjing 210008 Peoples R China Zhejiang Acad Agr Sci Inst Environm Resource Soil & Fertilizer Hangzhou 310021 Zhejiang Peoples R China

Volumetric water content of a silt loam soil (fluvo-aquic soil) in North China Plain was measured in situ by L-520 neutron probe (made in China) at three depths in the crop rootzone during a lysimeter experiment from 2001 to 2006. The electrical conductivity of the soil water (ECsw) was measured by salinity sensors buried in the soil during the same period at 10, 20,45 and 70 cm depth below soil surface. These data were used to test two mathematical procedures to predict water content and soil water salinity at depths of interest: all the available data were divided into training and testing datasets, then back propagation neural networks (BPNNs) were optimized by sensitivity analysis to minimizing the performance error, and then were finally used to predict soil water and ECsw. In order to meet with the prerequisite of autoregressive integrated moving average (ARIMA) model, firstly, original soil water content and ECsw time series were likewise transformed to obtain stationary series. Subsequently, the transformed time series were used to conduct analysis in frequency domain to obtain the parameters of the ARIMA models for the purposes of using the ARIMA model to predict soil water content and ECsw. Based on the statistical parameters used to assess model performance, the BPNN model performed better in predicting the average water content than the ARIMA model: coefficient of determination (R-2) = 0.8987, sum of squares error (SSE) = 0.000009, and mean absolute error (MAE) = 0.000967 for BPNN as compared to R-2 = 0.8867, SSE = 0.000043, MAE = 0.002211 for ARIMA. The BPNN model also performed better than the ARIMA model in predicting average ECsw of soil profile. However, the ARIMA model performed better than the BPNN models in predicting soil water content at the depth of 20 cm and ECsw at the depth of 10 cm below soil surface. Overall, the model developed by BPNN network showed its advantage of less parameter input, nonlinearity, simple model structure and good pre

关键词： Soil volumetric water content Soil electrical conductivity Back propagation neural network ARIMA transfer function model

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Nonparametric regression estimation in a null recurrent time series

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JOURNAL OF STATISTICAL PLANNING AND INFERENCE 2010年第12期140卷 3619-3626页

作者： Karlsen, Hans Arnfinn Myklebust, Terje Tjostheim, Dag Univ Bergen N-5020 Bergen Norway

We derive an asymptotic theory of nonparametric estimation for a time series regression model Z(t)=f(X(t))+W(t), where {X(t)} and {Z(t)} are observed nonstationary processes, and {W(t)} is an unobserved stationary process. The class of nonstationary processes allowed for {X(t)} is a subclass of the class of null recurrent Markov chains. This subclass contains the random walk, unit root processes and nonlinear processes. The process {W(t)} is assumed to be linear and stationary. (C) 2010 Published by Elsevier B.V.

关键词： Nonstationary time series Regression Null recurrent Markov chain Nonparametric kernel estimators transfer function model

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The effect of urbanization on stream hydrology in hillslope watersheds in central Texas

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HYDROLOGICAL PROCESSES 2010年第25期24卷 3706-3717页

作者： Sung, Chan Yong Li, Ming-Han Texas A&M Univ College Stn TX 78743 USA

This study examined the effect of urbanization on stream hydrology in hillslope watersheds. Ten streams (seven in hillslope and three in gentle slope watersheds) around Austin, Texas were selected for analysis. For each stream, we compared parameters of transfer function (TF) models estimated from daily rainfall and streamflow data collected in two study periods (October 1988-September 1992 and October 2004-September 2008) representing different degrees of watershed urbanization. As expected, the streams became more intermittent as the watersheds were more urbanized in all the study streams. However, the effect of urbanization on peakflow differs between hillslope and gentle slope watersheds. After watershed urbanization, peakflow increased in gentle slope watersheds, but decreased in hillslope watersheds. Based on the results of the TF models, we found that urbanization made stream not flashier but drier in hillslope watersheds. Overpumpage of aquifer has been recognized as a problem that leads to the stream dryness in the study area. However, the overpumpage alone cannot explain the differences in hydrological changes between the two types of watersheds. We attributed the reduced peakflow and stream dryness in the hillslope watersheds to land grading for construction forming stair-stepped or terraced landscape. Compared with natural hillslope, a stair-stepped landscape could infiltrate more stormwater by slowing down surface runoff on tread portions of the stair. Our findings suggest that a watershed management scheme should take into account local hydrogeologic conditions to mitigate the stream dryness resulting from urbanization in hillslope watersheds. Copyright (C) 2010 John Wiley & Sons, Ltd.

关键词： urban hydrogeology urban stream dryness transfer function model impulse response function Texas Hill Country

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Fisheries traffic: The poor relation of port devolution. Lessons from Spanish state ports of general interest

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MARINE POLICY 2010年第1期34卷 189-192页

作者： Castillo-Manzano, Jose I. Florido-Del-Corral, David Lopez-Valpuesta, Lourdes Univ Seville Dept Social Anthropol Res Grp Sociocultural Ident Studies Andalusia Seville Spain Univ Seville Fac Ciencias Econ & Empresariales Seville Spain

The fisheries sector is currently contending with the hectic development of its own political economy framework being convulsed by the dynamics of decentralisation. This process is enshrouded in an environment of economic globalisation, taking place against the backdrop of the governance approach. With this situation as the starting point, the main goal of this paper is to quantify the effects that the Spanish port devolution process might have on the Spanish fisheries sector through the use of a transfer function model;the volumes of landings at State ports of general interest and their cash value are taken as dependent variables. (C) 2009 Elsevier Ltd. All rights reserved.

关键词： Fisheries sector Port devolution Governance approach transfer function model Common Fisheries Policy

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Study on human auditory system models and risk assessment of noise induced hearing loss

Study on human auditory system models and risk assessment of...

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作者： Song, Won Joon University of Cincinnati

学位级别：Ph.D.

Simulation-based study of human auditory response characteristics and development of a prototype for advanced noise guideline are two major focuses of this dissertation research. This research was conducted as a part of the long-term effort to develop an improved noise guideline for better protection of the workers exposed to various noise environments.@pqdt@break@The human auditory responses were studied with simulation models. A human full-ear model derived from an existing model, Auditory Hazard Assessment Algorithm for Human (AHAAH), was utilized as a baseline for the study. Frequency- and time-domain responses of well-known human middle ear network models were cross-compared to estimate expected accuracy of the models and understand their proper use. Responses of the stapes to impulsive noises were investigated by using the middle ear models to understand the effects of the temporal characteristics of impulsive noises on the responses. Available measured transfer functions between the free-field pressure and the stapes response for human and chinchilla were also used to study the auditory response characteristics. The measured transfer functions were refined and reconditioned to make them have equivalent formats. Using the reconstructed transfer functions, time-domain stapes responses of human and chinchilla to impulsive and complex type noises were calculated and compared. Applicability of the noise metrics defined in terms of the stapes response to assess the risk of the noise induced hearing loss was studied.@pqdt@break@A prototype of an improved noise guideline was developed from existing chinchilla noise exposure data. Applying a new signal processing technique to the time histories of the exposed noises and studying the relationship between the noise metric and the permanent threshold shift (PTS), the dose-response relationship (DRR) was established in a compatible way with the definition used in current human noise guidelines. From the DDR, noise induced

关键词： Mechanical Engineering Auditory system modeling Network model Noise induced hearing loss transfer function model

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