scholarly journals The effect of age and study duration on the relationship between ‘clustering’ of DNA fingerprint patterns and the proportion of tuberculosis disease attributable to recent transmission

2001 ◽  
Vol 126 (1) ◽  
pp. 43-62 ◽  
Author(s):  
E. VYNNYCKY ◽  
N. NAGELKERKE ◽  
M. W. BORGDORFF ◽  
D. VAN SOOLINGEN ◽  
J. D. A. VAN EMBDEN ◽  
...  
Keyword(s):  
Age Groups ◽  
Dna Fingerprint ◽  
Older Individuals ◽  
Study Duration ◽  
Time Period ◽  
Recent Transmission ◽  
Dependent Risks ◽  
Age Structured ◽  
Age Structured Model ◽  
The Relationship

Though it is recognized that the extent of ‘clustering’ of isolates from tuberculosis cases in a given population is related to the amount of disease attributable to recent transmission, the relationship between the two statistics is poorly understood. Given age-dependent risks of disease and the fact that a long study (e.g. spanning several years) is more likely to identify transmission-linked cases than a shorter study, both measures, and thus the relationship between them, probably depend strongly on the ages of the cases ascertained and study duration. The contribution of these factors is explored in this paper using an age-structured model which describes the introduction and transmission of M. tuberculosis strains with different DNA fingerprint patterns in The Netherlands during this century, assuming that the number of individuals contacted by each case varies between cases and that DNA fingerprint patterns change over time through random mutations, as observed in several studies.Model predictions of clustering in different age groups and over different time periods between 1993 and 1997 compare well against those observed. According to the model, the proportion of young cases with onset in a given time period who were ‘clustered’ underestimated the proportion of disease attributable to recent transmission in this age group (by up to 25% in males); for older individuals, clustering overestimated this proportion. These under- and overestimates decreased and increased respectively as the time period over which the cases were ascertained increased. These results have important implications for the interpretation of estimates of the proportion of disease attributable to recent transmission, based on ‘clustering’ statistics, as are being derived from studies of the molecular epidemiology of tuberculosis in many populations.

POTENTIAL YIELD OF A ROCK SHRIMP STOCK, SICYONIA PENICILLATA IN THE NORTHERN GULF OF CALIFORNIA

Crustaceana ◽  
1999 ◽  
Vol 72 (6) ◽  
pp. 581-590 ◽  
Author(s):  
Juana Lopez-Martinez ◽  
Edgar Alcantara-Razo ◽  
Sergio Hernandez-Vazquez ◽  
Ernesto Chavez
Keyword(s):  
Gulf Of California ◽  
Age Groups ◽  
Potential Yield ◽  
Natural Oscillations ◽  
Recruitment Pattern ◽  
Stock Recruitment ◽  
Age Structured ◽  
Stochastic Recruitment ◽  
Age Structured Model ◽  
Compensatory Effect

AbstractA stock of rock shrimp Sicyonia penicillata was assessed in a fishery recently opened at Bahoa Kino, Sonora, Mexico. An age-structured model with stochastic recruitment was developed, which considers growth rate, natural mortality, and fishing mortality by age. Age groups were followed year by year with a stock-recruitment Ricker function where the seasonal recruitment pattern was defined as well. Simulations might be interpreted as showing a stable population with four year cycles, reflecting a density-dependent process. In 1996, fishing intensity had an apparent compensatory effect on the stock, decreasing the amplitude of natural oscillations and maintaining the stock at a biomass level similar to the size observed in a condition of no exploitation. The stock was found currently underexploited. As a result of the seasonal accessibility and the age of first-catch fishing (adult shrimp), the stock might be capable to withstand high fishing pressure without being overexploited. Se evaluo una poblacion de camaron de roca Sicyonia penicillata, de una pesqueroa recientemente abierta en Bahoa Kino, Sonora, Mexico. Se desarrollo un modelo basado en la estructura por edades que considera reclutamiento estocastico, tasa de crecimiento, mortalidad natural y mortalidad por pesca por grupo de edad. Estos grupos de edad fueron determinados ano tras ano mediante la funcion de reclutamiento de Ricker, en los que tambien se definio el patron estacional de reclutamiento. Las simulaciones muestran una poblacion estable con ciclos de cuatro anos, que indican un proceso de densodependencia. En 1996, la intensidad de pesca tuvo un efecto compensatorio sobre la poblacion, reduciendo la amplitud de las oscilaciones naturales y manteniendo al stock en un nivel de biomasa similar al observado en la condicion sin explotacion. Se encontro que el recurso esta subexplotado. Como resultado de la accesibilidad estacional y de que la edad de primera captura corresponde a camaron adulto, el recurso soporta alta presion de pesca sin dar evidencias de sobreexplotacion.

Environmental Variation and Recruitment of Pacific Herring (Clupea harengus pallasi) in the Strait of Georgia

1985 ◽  
Vol 42 (S1) ◽  
pp. s174-s180 ◽  
Author(s):  
Max Stocker ◽  
Vivian Haist ◽  
David Fournier
Keyword(s):  
Environmental Variables ◽  
River Discharge ◽  
Clupea Harengus ◽  
Pacific Herring ◽  
Strait Of Georgia ◽  
Clupea Harengus Pallasi ◽  
Age Structured ◽  
Age Structured Model ◽  
The Relationship ◽  
Spawning Success

We used an age-structured model to estimate recruitment for the Strait of Georgia Pacific herring (Clupea harengus pallasi) population. The model used for herring is a version of the model described in Fournier and Archibald (1982. Can. J. Fish. Aquat. Sci. 39: 1195–1207), modified to include spawn survey information. Three structural assumptions are made to include the spawn data: (1) the form of the relationship between the actual spawn and the observed spawn, (2) the form of the relationship between escapement and actual spawn, and (3) the existence of a Ricker spawn–recruitment relationship, with a multiplicative environmental component. In order to determine which environmental factors had a significant effect on recruitment, we attempted to explain the residual variation from the Ricker curve with the environmental variables using exploratory correlations. Temperature, river discharge, sea level, and sunlight were examined. A multiplicative, environmental-dependent Ricker spawn–recruitment model was used to identify significant environmental variables. The model suggests a significant dome-shaped relationship between temperature and spawning success with an optimal temperature during larval stages resulting in maximum production of recruits. Also, increased spawning success is associated with increased summer river discharge. The significant environmental variables were included in the age-structured model in a stock–environment–recruitment relationship, and all model parameters were reestimated. The overall model fit improved only marginally with the inclusion of environmental variables, as indicated by the objective function value. However, the S–R component of the objective function dropped by 23% when environmental variables were included.

scholarly journals The relationship between asthma and suicidal behaviours: a systematic literature review

2015 ◽  
Vol 46 (1) ◽  
pp. 96-106 ◽  
Author(s):  
Emma Barker ◽  
Kairi Kõlves ◽  
Diego De Leo
Keyword(s):  
Literature Review ◽  
Systematic Literature Review ◽  
English Language ◽  
Age Groups ◽  
Suicide Mortality ◽  
Original Research ◽  
Time Period ◽  
The Usa ◽  
Potential Link ◽  
The Relationship

Asthma is a highly prevalent chronic condition worldwide, and is particularly common in younger people compared to other chronic conditions. Asthma can result in a number of symptoms that are detrimental to the quality of life of sufferers. The aim of the present systematic literature review was to analyse the existing literature on the relationship between asthma and fatal and nonfatal suicidal behaviours.Articles were retrieved from Scopus, PubMed, ProQuest and Web of Knowledge. We searched for the terms (suicid* OR self-harm) AND (asthma* OR “bronchial hyperreactivity”) published in English-language peer-reviewed journals between 1990 and December 2014. Original research papers providing empirical evidence about the potential link between asthma and suicidal behaviours were included.The initial search identified 746 articles. Specific limiting criteria reduced the number of articles to the 19 articles that were finally included in the systematic review.The review found a potential link between asthma and suicide mortality, ideation and attempts across the age groups. Limitations of the review include the restriction to English-language papers published within the chosen time period, the limited number of papers involving suicide mortality, and the fact that the majority of papers originated from the USA.

scholarly journals COVID-19 Seroprevalence in Canada Modelling Waning and Boosting COVID-19 Immunity in Canada a Canadian Immunization Research Network Study

Vaccines ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 17
Author(s):  
David W. Dick ◽  
Lauren Childs ◽  
Zhilan Feng ◽  
Jing Li ◽  
Gergely Röst ◽  
...  
Keyword(s):  
Age Groups ◽  
Late Summer ◽  
Research Network ◽  
Age Group ◽  
Canadian Population ◽  
Waning Immunity ◽  
Age Structured ◽  
Changes Over Time ◽  
Age Structured Model ◽  
Do So

COVID-19 seroprevalence changes over time, with infection, vaccination, and waning immunity. Seroprevalence estimates are needed to determine when increased COVID-19 vaccination coverage is needed, and when booster doses should be considered, to reduce the spread and disease severity of COVID-19 infection. We use an age-structured model including infection, vaccination and waning immunity to estimate the distribution of immunity to COVID-19 in the Canadian population. This is the first mathematical model to do so. We estimate that 60–80% of the Canadian population has some immunity to COVID-19 by late Summer 2021, depending on specific characteristics of the vaccine and the waning rate of immunity. Models results indicate that increased vaccination uptake in age groups 12–29, and booster doses in age group 50+ are needed to reduce the severity COVID-19 Fall 2021 resurgence.

scholarly journals The relationship between transmission time and clustering methods inMycobacterium tuberculosisepidemiology

2018 ◽  
Author(s):  
Conor J Meehan ◽  
Pieter Moris ◽  
Thomas A. Kohl ◽  
Jūlija Pečerska ◽  
Suriya Akter ◽  
...  
Keyword(s):  
Democratic Republic Of Congo ◽  
Setting Time ◽  
Whole Genome Sequence ◽  
Clustering Methods ◽  
Time Period ◽  
Recent Transmission ◽  
Clustering Data ◽  
The Relationship ◽  
Selection Of

AbstractBackgroundTracking recent transmission is a vital part of controlling widespread pathogens such asMycobacterium tuberculosis. Multiple methods with specific performance characteristics exist for detecting recent transmission chains, usually by clustering strains based on genotype similarities. With such a large variety of methods available, informed selection of an appropriate approach for determining transmissions within a given setting/time period is difficult.MethodsThis study combines whole genome sequence (WGS) data derived from 324 isolates collected 2005-2010 in Kinshasa, Democratic Republic of Congo (DRC), a high endemic setting, with phylodynamics to unveil the timing of transmission events posited by a variety of standard genotyping methods. Clustering data based on Spoligotyping, 24-loci MIRU-VNTR typing, WGS based SNP (Single Nucleotide Polymorphism) and core genome multi locus sequence typing (cgMLST) typing were evaluated.FindingsOur results suggest that clusters based on Spoligotyping could encompass transmission events that occurred over 70 years prior to sampling while 24-loci-MIRU-VNTR often represented two or more decades of transmission. Instead, WGS based genotyping applying low SNP or cgMLST allele thresholds allows for determination of recent transmission events in timespans of up to 10 years e.g. for a 5 SNP/allele cut-off.InterpretationWith the rapid uptake of WGS methods in surveillance and outbreak tracking, the findings obtained in this study can guide the selection of appropriate clustering methods for uncovering relevant transmission chains within a given time-period. For high resolution cluster analyses, WGS-SNP and cgMLST based analyses have similar clustering/timing characteristics even for data obtained from a high incidence setting.

scholarly journals Age and the Thyrotropin Response to Hypothyroxinemia

2010 ◽  
Vol 95 (8) ◽  
pp. 3675-3683 ◽  
Author(s):  
Rebecca Over ◽  
Sonia Mannan ◽  
Hala Nsouli-Maktabi ◽  
Kenneth D. Burman ◽  
Jacqueline Jonklaas
Keyword(s):  
Age Groups ◽  
Primary Hypothyroidism ◽  
Age Group ◽  
Older Individuals ◽  
Free T4 ◽  
Pathological Alteration ◽  
The Mean ◽  
The Relationship ◽  
Two Populations ◽  
Serum Tsh

Context: Some studies suggest altered pituitary functioning and TSH production with aging. Objective: Our objective was to test the hypothesis that less TSH production occurs despite comparable hypothyroxinemia with advancing age. Design: We retrospectively studied adult outpatients of all ages with confirmed hypothyroidism and documented their TSH and free T4 concentrations. Participants: Two populations of 112 patients were subdivided into four age groups: 1) patients newly diagnosed with primary hypothyroidism and 2) thyroid cancer patients undergoing l-T4 withdrawal in preparation for diagnostic or therapeutic radioiodine. Main Outcome Measure: The relationship between paired free T4 and TSH concentrations and patient age was studied. Results: With spontaneous hypothyroidism, the mean TSH concentration decreased nonsignificantly in each ascending age group with comparable free T4 (FT4) concentrations (<35 yr, 69 mIU/liter; 35–49 yr, 49 mIU/liter; 50–64 yr, 43 mIU/liter; >64 yr, 29 mIU/liter). With iatrogenic hypothyroidism, the mean TSH concentration decreased significantly in each ascending age group (<35 yr, 156 mIU/liter; 35–49 yr, 115 mIU/liter; 50–64 yr, 74 mIU/liter; >64 yr, 46 mIU/liter; P < 0.001) despite similar FT4 concentrations. The relationship between the log-transformed TSH and FT4 was significantly and inversely affected by age in multivariate analyses in both spontaneous hypothyroidism (P = 0.0005) and in iatrogenic hypothyroidism (P < 0.0001). Conclusions: Age modifies the pituitary set point or response to comparably reduced free T4 concentrations, resulting in lesser serum TSH elevation in older individuals. This phenomenon occurs with both spontaneous and iatrogenic hypothyroidism. This may be an adaptive response in normal aging or a pathological alteration of pituitary function with age.

scholarly journals Variation in the catchability of yellow perch (Perca flavescens) in the fisheries of Lake Erie using a Bayesian error-in-variable approach

2006 ◽  
Vol 63 (9) ◽  
pp. 1695-1704 ◽  
Author(s):  
Yan Jiao ◽  
Kevin Reid ◽  
Tom Nudds
Keyword(s):  
Population Size ◽  
Yellow Perch ◽  
Lake Erie ◽  
Perca Flavescens ◽  
Catch Per Unit Effort ◽  
Management Units ◽  
Variable Approach ◽  
Time Period ◽  
Age Structured ◽  
Age Structured Model

Abstract Catch per unit effort (cpue) from fisheries, and abundance or biomass indices from fishery-independent surveys are often used to infer the dynamics of exploited populations. To do this, cpues and survey indices are usually assumed to be proportional to population size or biomass. Four sources of data on the cpue of yellow perch (Perca flavescens) in Lake Erie were available to evaluate this assumption: commercial gillnet and trapnet fisheries, an angling fishery, and a fishery-independent gillnet survey. The relationships between fisheries cpue and population biomass (estimated from an age-structured model), and between fisheries and survey cpues were analysed by error-in-variable (EIV) models because of the absence of independent estimates of population size. Cpues were not proportional to population size, estimated by biomass. Catchabilities varied widely among fisheries (gear types), time period, and areas (management units) within Lake Erie. A spatial EIV model showed that the migrations among management units were considerable. The whole-lake spatial EIV model showed that cpues were not proportional to population size.

scholarly journals The Discrete Time-Space SIR-SI Age-Structured Model for Leptospirosis

2018 ◽  
Vol 7 (4.30) ◽  
pp. 484
Author(s):  
Nor Azah Samat ◽  
Aznida Che Awang
Keyword(s):  
Discrete Time ◽  
Disease Transmission ◽  
Transition Rate ◽  
Age Groups ◽  
Future Application ◽  
Structured Model ◽  
Time Space ◽  
Age Structured ◽  
Age Structured Model ◽  
Transmission Models

The aim of this study is to introduce new discrete time-space SIR-SI age-structured disease transmission models for Leptospirosis disease. The term “age-structured” here refers to having two different age groups, which are children and adult. These models are important because it will later lead to a conclusion of whether children or adult have high risk of being infected by Leptospirosis disease. In this study, two types of SIR-SI age-structured models are introduced. These include models with and without the transition rate between age groups. The future application of these two models will be based on the availability of parameter value and Leptospirosis data.

scholarly journals Future scenarios for the SARS-CoV-2 epidemic in Switzerland: an age-structured model

F1000Research ◽  
2021 ◽  
Vol 9 ◽  
pp. 646
Author(s):  
Janne Estill ◽  
Plamenna Venkova-Marchevska ◽  
Maroussia Roelens ◽  
Erol Orel ◽  
Alexander Temerev ◽  
...  
Keyword(s):  
Intensive Care Unit ◽  
Intensive Care ◽  
Compartmental Model ◽  
Critical Level ◽  
Age Groups ◽  
Future Scenarios ◽  
Structured Model ◽  
Increased Risk ◽  
Age Structured ◽  
Age Structured Model

The recent lifting of COVID-19 related restrictions in Switzerland causes uncertainty about the future of the epidemic. We developed a compartmental model for SARS-CoV-2 transmission in Switzerland and projected the course of the epidemic until the end of year 2020 under various scenarios. The model was age-structured with three categories: children (0-17), adults (18-64) and seniors (65- years). Lifting all restrictions according to the plans disclosed by the Swiss federal authorities by mid-May resulted in a rapid rebound in the epidemic, with the peak expected in July. Measures equivalent to at least 76% reduction in all contacts were able to eradicate the epidemic; a 54% reduction in contacts could keep the intensive care unit occupancy under the critical level and delay the next wave until October. In scenarios where strong contact reductions were only applied in selected age groups, the epidemic could not be suppressed, resulting in an increased risk of a rebound in July, and another stronger wave in September. Future interventions need to cover all age groups to keep the SARS-CoV-2 epidemic under control.

scholarly journals Future scenarios for the SARS-CoV-2 epidemic in Switzerland: an age-structured model

2020 ◽  
Author(s):  
Janne Estill ◽  
Plamenna Venkova-Marchevska ◽  
Maroussia Roelens ◽  
Erol Orel ◽  
Alexander Temerev ◽  
...  
Keyword(s):  
Intensive Care Unit ◽  
Intensive Care ◽  
Compartmental Model ◽  
Critical Level ◽  
Age Groups ◽  
Future Scenarios ◽  
Structured Model ◽  
The Future ◽  
Age Structured ◽  
Age Structured Model

The recent lifting of COVID-19 related restrictions in Switzerland causes uncertainty about the future of the epidemic. We developed a compartmental model for SARS-CoV-2 transmission in Switzerland and projected the course of the epidemic until the end of year 2020 under various scenarios. The model was age-structured with three categories, children (0-17), adults (18-64) and seniors (65- years). Lifting all restrictions according to the plans disclosed by the Swiss federal authorities by mid-May resulted in a rapid rebound in the epidemic, with the peak expected in July. Measures equivalent to at least 90% reduction in all contacts were able to eradicate the epidemic; 56% reduction in contacts could keep the intensive care unit occupancy under the critical level, and delay the next wave until October. Scenarios where strong contact reductions were only applied in selected age groups could not suppress the epidemic, increasing the risk of a next wave in July, and another stronger wave in September. Future interventions need to cover all age groups to keep the SARS-CoV-2 epidemic under control.

Sign in / Sign up

Export Citation Format

Share Document