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A primer on stable parameter estimation and forecasting in epidemiology by a problem-oriented regularized least squares algorithm

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Infectious Disease Modelling 2017年第2期2卷 268-275页

作者： Alexandra Smirnova gerardo Chowell Department of Mathematics and Statistics Georgia State UniversityAtlantaUSA School of Public Health Georgia State UniversityAtlantaUSA Division of International Epidemiology and Population Studies Fogarty International CenterNational Institutes of HealthBethesdaMDUSA

Public health officials are increasingly recognizing the need to develop disease-forecasting systems to respond to epidemic and pandemic *** instance,simple epidemic models relying on a small number of parameters can play an important role in characterizing epidemic growth and generating short-term epidemic *** the absence of reliable information about transmission mechanisms of emerging infectious diseases,phenomenological models are useful to characterize epidemic growth patterns without the need to explicitly model transmission mechanisms and the natural history of the *** this article,our goal is to discuss and illustrate the role of regularization methods for estimating parameters and generating disease forecasts using the generalized Richards model in the context of the 2014e15 Ebola epidemic in West Africa.

关键词： Generalized Richards model Parameter estimation Regularization methods Epidemic forecasting Ebola

Focus on acute diarrhoeal disease

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World Journal of Gastroenterology 2009年第27期15卷 3341-3348页

作者： Fabio Baldi Maria Antonia Bianco gerardo Nardone Alberto Pilotto Emanuela Zamparo Gastroenterology Unit S. Orsola-Malpighi HospitalVia Massarenti 9 40138 Bologna Italy

Diarrhoea is an alteration of normal bowel movement characterized by an increase in the water content, volume, or frequency of stools. Diarrhoea needs to be classif ied according to the trends over time (acute or chronic) and to the characteristics of the stools (watery, fatty, inflammatory). Secretory diarrhoeas, mostly acute and of viral aetiology in more than 70% of cases, are by far the most important subtype of diarrhoeas in terms of frequency, incidence and mortality (over 2.5 million deaths/year in developing countries). Natural and synthetic opiates such as morphine, codeine, and loperamide which react with endogenous opiates (enkephalins, beta-endorphins, dynorphins) mainly act on intestinal motility and slow down transit. An antidiarrhoeal drug developed in recent years, racecadotril, acts as an enkephalinase inhibitor. Clinical studies have shown that it is just as effective as loperamide in resolving acute diarrhoea but with greater reduction in pain and abdominal distension. Some studies have explored the prevalence of diarrhoea in old age. An epidemiological study carried out in Italy by 133 General Practitioners on 5515 elderly outpatients reported a prevalence of diarrhoea, def ined according to the Rome criteria, of 9.1%. Infectious diseases (19%) and drug use (16%) were the most common causes of diarrhoea in old age. Regardless of the cause, the treatment of elderly patients with diarrhoea must include rehydration and nutritional support. Every year, more than 50 million tourists travel from industrialized countries to places where hygiene levels are poor. At least 75% of those travelling for short periods mention health problems, and in particular traveller's diarrhoea.

关键词：急性腹泻病治疗方法临床分析发病率

Influence of steel jacket thickness on the RC bridges' seismic vulnerability

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Journal of Traffic and Transportation Engineering(English Edition) 2019年第1期6卷 15-34页

作者： Bertha Olmos José Manuel Jara gerardo Gómez Guillermo Martínez Department of Civil Engineering Universidad Michoacana de San Nicolas de Hidalgo

The seismic demands of bridges subjected to strong earthquakes are mostly concentrated on piers. The main objective of this study is to assess the seismic vulnerability of retrofitted bridges with steel jackets. It analyzes the influence of the steel jacket thickness on the seismic capacity and demand of bridges. The bridges in study have two simple supported spans with superstructure composed by AASHTO type girders and a substructure formed with one circular pier over a stiff foundation. They are located on the Pacific coast of Mexico that is a zone of high seismicity. The bridges seismic capacity are evaluated through nonlinear static analyses and the shear force and displacement demands were determined using capacity spectra with a group of 10 real accelerograms from a subduction source. The response spectra were scaled to several peak ground accelerations(PGA) with the aim to estimate four damage scenarios linked each one to a probability of exceedance in a specific period, for return periods in the range of 72-3500 years that represent service level and maximum considered earthquake. Results show that the confining effect provided by the steel jackets substantially improves the seismic performance of the bridges piers. The increase of jacket thickness guides to important increments on columns base shear capacity, and the influence of the steel jacket thickness depends on the limit state and bridge slenderness ratio.

关键词： Steel jacket Piers’retrofit Subduction earthquakes RC piers’vulnerability

Effects of corn gluten feed inclusion at graded levels in a corn-soybean diet on the ileal and fecal digestibility of growing pigs

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Journal of Animal Science and Biotechnology 2015年第1期6卷 63-68页

作者： gerardo Mariscal Landin Tercia Cesaria Reis de Souza Ericka Ramirez Rodriguez Centro Nacional de Investigacion en Fisiologia Animal Instituto Nacional de Investigaciones Forestales Agricolas y PecuariasKm 1Carretera a ColonAjuchitlan ColonQueretaro 76280Mexico Facultad de Ciencias Naturales Universidad Autonoma de QueretaroSantiago de QueretaroAv.De las Ciencias s/n Juriquilla 76000QueretaroQueretaroMexico

Background： This study aimed to determine the effect of the inclusion of corn gluten feed （CGF） on the apparent and standardized ileal digestibility of protein and amino acids and the apparent ileal and total tract digestibility of energy in growing pigs. The study was performed using 16 barrows （weight, 45.3 ±4.5 kg） that were fitted with a T cannula at the terminal ileum. There were four treatments： a corn-soybean diet without CGF and three corn-soybean diets containing increasing levels of CGF （65, 130, and 195 g/kg）. Data were analyzed according to a randomized complete block design, four blocks with four pigs each （one pig per treatment）. The trend of the response （linear or quadratic） was determined using orthogonal contrasts, and when a linear effect was determined, a linear equation was obtained. Results： The results showed that the inclusion up to 195 g/kg of CGF in the corn-soybean diet did not diminish the ileal digestibility （apparent and standardized） of protein and amino acids （P 〉 0.05）, except that of phenylalanine, cystine, and proline. A linear decrease （P 〈 0.05） per gram of CGF added to the diet in the apparent and standardized ileal digestibility of phenylalanine （0.011 and 0.015 percentage units, respectively）, cystine （0.048 and 0.043 percentage units, respectively）, and proline （0.045 and 0.047 percentage units, respectively） was noted. Similarly, ileal digestibility of dry matter and energy were adversely affected （reduced by 0.028 and 0.025 percentage units, respectively, per gram of CGF increment in the diet）. A significant （P 〈 0.05） linear reduction in total tract digestibility with increase in CGF amount in the diet was observed for energy （0.027 percentage units）, dry matter （0.027 percentage units）, crude protein （0.020 percentage units）, and neutral detergent fiber （0.041 percentage units） per gram of CGF added to the diet. Conclusion： CGF did not affect the ileal digestibility of protein and most amino acids but reduced the ileal an

关键词： Amino acids Corn gluten feed Energy Ileal digestibility Pigs Total tract digestibility

Topographic effects observed at Amatrice hill during the 2016-2017 Central Italy seismic sequence

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Earthquake Engineering and Engineering Vibration 2021年第1期20卷 63-78页

作者： gerardo Grelle Laura Bonito Maresca Rosalba Silvia Iacurto Claudia Madiai Paola Revellino Giuseppe Sappa Department of Civil Building and Environmental EngineeringSapienza University of RomeItaly Department of Sciences and Technologies University of SannioItaly Department of Civil and Environmental Engineering University of FlorenceItaly

The estimate of seismic site effects by experimental approaches is based on different assumptions aimed at simplifying the complex actual site conditions and related ***,the reliability of the results can increase if the experimental data is focused on quite strong seismic sequences and the on-site acquisition of a large number of signals is deemed strategic for the assessment of the expected *** on these considerations,the ground motion at the Red Zone sector of Amatrice hill,violently struck by the 2016-2017 Central Italy seismic sequence,was analyzed via an observational approach.A large set of weak motions(moment magnitude Mw 2.5-3.9)was analyzed in this study by means of standard(SSR)and horizontal to vertical(HVSR)spectral ratio *** results from the experimental analysis of the site effects by using weak motion and noise signals show a significant amplification at the top of Amatrice hill with a remarkable polarization of the motion and changes in spectral shapes according to the topographic setting of the relief.

关键词： topographic effects standard spectra ratio(SSR) horizontal and vertical spectral ratio(HVSR) directional effects

Model based current mode control design and experimental validation for a 3φ rectifier under unbalanced grid voltage conditions

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Journal of Modern Power Systems and Clean Energy 2018年第4期6卷 777-790页

作者： P.R.MARTíNEZ-RODRIGEZ Jose M.SOSA Samuel ITURRIAGA-MEDINA gerardo ESCOBAR gerardo VáZQUEZ-GUZMáN Andres A.VALDEZ-FERNáNDEZ School of Sciencies UASLP Laboratory of Electrical and Power Electronics ITESI School of Engineering Universidad Modelo

This paper addresses the control design and the experimental validation of a current mode control for a three phase voltage source rectifier. The proposed control law is able to fulfill the voltage regulation and the current tracking control objectives despite of unbalanced and distorted grid voltages. The proposed control law consists of two loops, which are referred as inner tracking loop and the outer voltage regulation loop. The inner loop is designed to provide damping to the system, which also includes and adaptive mechanism. The construction of the current reference is based on the positive component detection of thegrid voltage. Therefore, the current produced by the power rectifier is proportional to the fundamental component of the grid voltage, despite of the presence of unbalanced grid voltages. The voltage regulation loop is designed as a proportional-integral controller, which is aimed to regulate the DC output voltage to a desired level. Finally, experimental results are obtained in an experimental prototype of2 kW to evaluate the performance of the proposed controller.

关键词： Pulse-width modulation rectifier Power factor correction Positive-component Current mode control

Modelling and simulating Chikungunya spread with an unstructured triangular cellular automata

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Infectious Disease Modelling 2020年第1期5卷 197-220页

作者： gerardo Ortigoza Fred Brauer Iris Neri Facultad de Ingeniería Universidad VeracruzanaBoca Del RíoVerMexico Mathematics Department University of British ColumbiaVancouverB.CCanada Maestría en Gestion Integrada de Cuencas Universidad Autonoma de QueretaroMexico

In this work we propose a mathematical model to simulate Chikungunya spread;the spread model is implemented in a C++ cellular automata code defined on unstructured triangular grids and space visualizations are performed with *** order to simulate the time space spread of the Chikungunya diseases we include assumptions such as:heterogeneous human and vector densities,population mobility,geographically localized points of infection using geographical information systems,changes in the probabilities of infection,extrinsic incubation and mosquito death rate due to environmental *** experiments reproduce the qualitative behavior of diseases spread and provide an insight to develop strategies to prevent the diseases spread.

关键词： Cellular automata Unstructured triangular grids Chikungunya spread

Systematic comparison of epidemic growth patterns using two different estimation approaches

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Infectious Disease Modelling 2021年第1期6卷 5-14页

作者： Yiseul Lee Kimberlyn Roosa gerardo Chowell Department of Population Health Sciences School of Public HealthGeorgia State UniversityAtlantaGA30303USA Division of International Epidemiology and Population Studies Fogarty International CenterNational Institute of HealthBethesdaMD20892USA UT One Health Initiative University of TennesseeKnoxvilleTN37996USA

Background:Different estimation approaches are frequently used to calibrate mathematical models to epidemiological data,particularly for analyzing infectious disease ***,we use two common methods to estimate parameters that characterize growth patterns using the generalized growth model(GGM)calibrated to real outbreak *** and methods:Data from 31 outbreaks are used to fit the GGM to the ascending phase of each outbreak and estimate the parameters using both least squares(LSQ)and maximum likelihood estimation(MLE)*** utilize parametric bootstrapping to construct confidence intervals for parameter *** compare the results including RMSE,Anscombe residual,and 95%prediction interval *** also evaluate the correlation between the estimates from both ***:Comparing LSQ and MLE estimates,most outbreaks have similar parameter estimates,RMSE,Anscombe,and 95%prediction interval *** estimates do not differ across methods when the model yields a good fit to the early growth ***,for two outbreaks,there are systematic deviations in model fit to the data that explain differences in parameter estimates(e.g.,residuals represent random error rather than systematic deviation).Conclusion:Our findings indicate that utilizing LSQ and MLE methods produce similar results in the context of characterizing epidemic growth patterns with the GGM,provided that the model yields a good fit to the data.

关键词： Parameter estimation Generalized growth model Least squares estimation Maximum likelihood estimation Epidemiological models

Resistance to the Whitefly Aleurotrachelus socialis(Hemiptera:Aleyrodidae) and SSR Marker Identification in Advanced Populations of the Hybrid Manihot esculenta *** flabellifolia

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Journal of Integrative Agriculture 2013年第12期12卷 2217-2228页

作者： Arturo Carabalí James Montoya-Lerma Anthony C Belloti Martin Fregene gerardo Gallego Deparment of Biology Universidad del Valle International Center of Tropical Agriculture (CIAT)

Genes resistant to Aleurotrachelus socialis were transferred to the F 1 from the interspecific hybrid wild species of Manihot flabellifolia to *** and two advanced generations of backcrosses（BC 1 and BC 2）.We characterized the resistance of *** transferred to BC 2 parents（CW67-160,CW67-130,CW67-44）,MTAI-8（BC 1）,resistant（CMB9B-73） and susceptible（CMB9B-104） genotypes from contrasting pools,and resistant（MEcu-72） and susceptible（CMC-40） *** demography and biology were *** molecular markers associated with a phenotypic response of plant resistance were detected in segregating populations（BC 2）.Results showed that although female survival time was similar on all hosts,the lowest averages of longevity,fecundity and oviposition rate were observed in the resistant control MEcu- 72,only being significantly similar to the parent *** the BC 1 and BC 2 populations were compared,it was found that *** fecundity was eight times lower on CMB9B-73 progeny than on CW67-130,expressing the highest levels of resistance to the *** genotypes of CMB9A and CMB9B family had the best segregation.A total of 486 microsatellite primers were evaluated using bulked segregant analysis（BSA）,11 showed polymorphism between the contrasting pools and only one showed significant differences between resistant and susceptible *** conclusion,fecundity was the parameter that impacted most on the intrinsic rate of *** population growth.

关键词： cassava wild parents interspecific hybrids whitefly resistance BSA