scholarly journals COVID-19 in Chile: The usefulness of simple epidemic models in practice

Medwave ◽  
2021 ◽  
Vol 21 (01) ◽  
pp. e8119-e8119
Author(s):  
Mauricio Canals ◽  
Cristóbal Cuadrado ◽  
Andrea Canals
Keyword(s):  
Gompertz Model ◽  
Time Frame ◽  
Type Model ◽  
Local Behavior ◽  
Discrete Equations ◽  
The Monte Carlo Method ◽  
Great Utility ◽  
Short And Long Term ◽  
Short Time

Objectives The purpose of this article is to describe and develop the predictive value of three models during the COVID-19 epidemic in Chile, providing knowledge for decision-making in health. Methods We developed three models during the epidemic: a discrete model to predict the maximum burden on the health system in a short time frame—a basic SEIR (susceptible-exposed-infected-removed) model with discrete equations; a stochastic SEIR model with the Monte Carlo method; and a Gompertz-type model for metropolitan city of Santiago. Results The maximum potential burden model has been useful throughout the monitoring of the epidemic, providing an upper bound for the number of cases, intensive care unit occupancy, and deaths. Deterministic and stochastic SEIR models were very useful in predicting the rise of cases and the peak and onset of case decline; however, they lost utility in the current situation due to the asynchronous recruitment of cases in the regions and the persistence of a strong endemic. The Gompertz model had a better fit in the decline since it best captures the epidemic curve’s asymmetry in Santiago. Conclusions The models have shown great utility in monitoring the epidemic in Chile, with different objectives in different epidemic stages. They have complemented empirical indicators such as reported cases, fatality, deaths, and others, making it possible to predict situations of interest and visualization of the short and long-term local behavior of this pandemic.

scholarly journals Continuous Viral Escape and Selection by Autologous Neutralizing Antibodies in Drug-Naïve Human Immunodeficiency Virus Controllers

2008 ◽  
Vol 83 (2) ◽  
pp. 662-672 ◽  
Author(s):  
Madhumita Mahalanabis ◽  
Pushpa Jayaraman ◽  
Toshiyuki Miura ◽  
Florencia Pereyra ◽  
E. Michael Chester ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
Neutralizing Antibodies ◽  
Time Frame ◽  
Continuous Selection ◽  
Viral Escape ◽  
Elite Controllers ◽  
Hiv Replication ◽  
Immunodeficiency Virus ◽  
Short Time

ABSTRACT We assessed differences in the character and specificity of autologous neutralizing antibodies (ANAbs) against individual viral variants of the quasispecies in a cohort of drug-naïve subjects with long-term controlled human immunodeficiency virus type 1 (HIV-1) infection and moderate levels of broad heterologous neutralizing antibodies (HNAb). Functional plasma virus showed continuous env evolution despite a short time frame and low levels of viral replication. Neutralization-sensitive variants dominated in subjects with intermittent viral blips, while neutralization-resistant variants predominated in elite controllers. By sequence analysis of this panel of autologous variants with various sensitivities to neutralization, we identified more than 30 residues in envelope proteins (Env) associated with resistance or sensitivity to ANAbs. The appearance of new sensitive variants is consistent with a model of continuous selection and turnover. Strong ANAb responses directed against autologous Env variants are present in long-term chronically infected individuals, suggesting a role for these responses in contributing to the durable control of HIV replication.

scholarly journals Longitudinal prediction of falls and near falls frequencies in Parkinson’s disease: a prospective cohort study

2020 ◽  
Author(s):  
Beata Lindholm ◽  
Christina Brogårdh ◽  
Per Odin ◽  
Peter Hagell
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Prospective Cohort ◽  
Prediction Models ◽  
Evidence Base ◽  
History Of ◽  
Short And Long Term ◽  
Near Falls ◽  
Short Time

Abstract Introduction and objective Several prediction models for falls/near falls in Parkinson’s disease (PD) have been proposed. However, longitudinal predictors of frequency of falls/near falls are poorly investigated. Therefore, we aimed to identify short- and long-term predictors of the number of falls/near falls in PD. Methods A prospective cohort of 58 persons with PD was assessed at baseline (mean age and PD duration, 65 and 3.2 years, respectively) and 3.5 years later. Potential predictors were history of falls and near falls, comfortable gait speed, freezing of gate, dyskinesia, retropulsion, tandem gait (TG), pain, and cognition (Mini-Mental State Exam, MMSE). After each assessment, the participants registered a number of falls/near falls during the following 6 months. Multivariate Poisson regression was used to identify short- and long-term predictors of a number of falls/near falls. Results Baseline median (q1–q3) motor (UPDRS) and MMSE scores were 10 (6.75–14) and 28.5 (27–29), respectively. History of falls was the only significant short-time predictor [incidence rate ratio (IRR), 15.17] for the number of falls/near falls during 6 months following baseline. Abnormal TG (IRR, 3.77) and lower MMSE scores (IRR, 1.17) were short-term predictors 3.5 years later. Abnormal TG (IRR, 7.79) and lower MMSE scores (IRR, 1.49) at baseline were long-term predictors of the number of falls/near falls 3.5 years later. Conclusion Abnormal TG and MMSE scores predict the number of falls/near falls in short and long term, and may be indicative of disease progression. Our observations provide important additions to the evidence base for clinical fall prediction in PD.

scholarly journals The Progressive Response of Sahelian Dams to Sediment Intrusion: Case of Kano State between 1976 and 2009

2015 ◽  
Vol 773-774 ◽  
pp. 1301-1306
Author(s):  
Mahadi Lawan Yakubu ◽  
Usman Tasiu Abdurrahman ◽  
Muhammad Tajuri Ahmed ◽  
Amina Sallau Aliyu ◽  
Muttaqa Uba Zango ◽  
...  
Keyword(s):  
Management Strategies ◽  
Water Storage ◽  
Time Frame ◽  
Mitigation Strategy ◽  
The State ◽  
Best Management ◽  
The Future ◽  
Short And Long Term

Reservoirs are built to store water during abundance for possible reuse during scarcity; sediment incursion is the leading phenomenon that limit reservoirs to sustain this function. Therefore, modelling the rate at which reservoir accumulates sediments is critical in understanding the nature of the problem, the time frame within which it is expected to occur, and the best mitigation strategy that will maintain the reservoir service. This study investigated the sediment influx in three typical Sahelian reservoirs in Kano state using the bathymetric method. The reservoir capacities were found to be declining at different rates but with grave consequences on the future, and economy of the state. In prolific terms, the state is losing 490 million litres of water storage each year. Presently, Magaga lost 39% of its capacity; Thomas has lost 13%; while Kafin-chiri has lost 5%. For sustainability, this trend needs to be addressed. The short and long-term best management strategies to curtail this trend have been outlined in this study.

Intermediate and Long-Term Radiological Consequences of an Uncontrolled Access of Saline Solution Into the Asse Mine

2011 ◽  
Author(s):  
Veronika Ustohalova ◽  
Christian Ku¨ppers
Keyword(s):  
Saline Solution ◽  
Anthropogenic Activities ◽  
Decay Chain ◽  
Radionuclide Migration ◽  
Chain Migration ◽  
Geological Conditions ◽  
Short And Long Term ◽  
Radionuclide Release ◽  
Short Time

The risk of radioactive contamination in the biosphere surrounding the Asse salt mine has been assessed to determine the possible radioactive exposure to humans if the mine collapses. Geological conditions and anthropogenic activities have made the mine instable and allow salt-saturated ground water to seep in. This uncontrolled brine inflow significantly increases the risk of the mine collapsing. If the mine collapses, the brine will be pressed into groundwater, where the radionuclides can migrate into the biosphere and cause radioactive exposure. The key issue discussed in this paper is estimating the short- and long-term radiation burden for humans under several possible scenarios of radionuclide release. Only a radioecological model able to quantify and estimate processes taking place can generate usable results. This work develops the radioecological model describing both radionuclide migration and the resulting radiological exposure along several exposition pathways. Development of the model took into account the sorption processes, solubility limits and special aspects of decay chain migration. The radiological exposure was estimated under non-equilibrated conditions for the case of short-time expositions. At the end of this paper, the model’s background, the results of the computations and a comparison of several scenarios will be presented.

Determination of native (wood derived) formaldehyde by the desiccator method in particleboards generated during panel production

Holzforschung ◽  
2010 ◽  
Vol 64 (4) ◽  
Author(s):  
Michael J. Birkeland ◽  
Linda Lorenz ◽  
James M. Wescott ◽  
Charles R. Frihart
Keyword(s):  
Hot Pressing ◽  
Urea Formaldehyde ◽  
Chromotropic Acid ◽  
Monitoring Methods ◽  
Emission Testing ◽  
Short And Long Term ◽  
The Common ◽  
Short Time

Abstract Hot-pressing wood, particularly in the production of wood composites, generates significant “native” (wood-based) formaldehyde (FA), even in the absence of adhesive. The level of native FA relates directly to the time and temperature of hot-pressing. This native FA dissipates in a relatively short time and is not part of the long-term FA emission issue commonly associated with hydrolyzing urea-formaldehyde bonds. This paper demonstrates that the common desiccator/chromotropic acid method is very specific for FA and is not influenced by other volatile compounds set free from wood during hot-pressing. Furthermore, it is shown that particleboard produces native FA at high levels even in the absence of adhesives or in the presence of one type of no-added formaldehyde (NAF) adhesive. Soy-based adhesives suppress native FA emission and provide low FA emission levels in both the short and long term. This study highlights an often overlooked aspect that should be considered for emission testing: standardizing the time and conditions employed immediately after pressing and prior to the onset of emissions testing. Addressing this issue in more detail would improve the reliability of correlation between data obtained by rapid process monitoring methods and emission measurements in large chambers.

Damage Assessment and Residual Service Life Estimation of Cracked Timber Beams

2013 ◽  
Vol 778 ◽  
pp. 402-409 ◽  
Author(s):  
Jan Willem G. van de Kuilen ◽  
Wolfgang Gard
Keyword(s):  
Service Life ◽  
Time Frame ◽  
Practical Case ◽  
Residual Service Life ◽  
Time To Failure ◽  
Service Life Estimation ◽  
Short Time ◽  
Residual Service ◽  
Timber Beams

Service life modelling of cracked timber beams can be performed using modified damage accumulation models that describe the combined effect or long term loads (mechanical) and biological of physical wood degradation. The combined model allows for the estimation of residual service life and an analysis of crack development. The model can also be used to analyse safety factors that may need to be applied. Also, a sensitivity analysis can be performed for future risks. It is shown that the failure risk is very sensitive to the level of the applied loads, similar to time to failure analysis of non-degraded timber. Failure in timber structures occurs within a very short time frame. A practical case of cracked glulam beams is included in the paper.

scholarly journals Empirical model for short-time prediction of COVID-19 spreading

2020 ◽  
Vol 16 (12) ◽  
pp. e1008431
Author(s):  
Martí Català ◽  
Sergio Alonso ◽  
Enrique Alvarez-Lacalle ◽  
Daniel López ◽  
Pere-Joan Cardona ◽  
...  
Keyword(s):  
Health Workers ◽  
Gompertz Model ◽  
Control Measures ◽  
Short Term ◽  
Spreading Velocity ◽  
Current State ◽  
Term Evolution ◽  
Public Health Workers ◽  
Short Time

The appearance and fast spreading of Covid-19 took the international community by surprise. Collaboration between researchers, public health workers, and politicians has been established to deal with the epidemic. One important contribution from researchers in epidemiology is the analysis of trends so that both the current state and short-term future trends can be carefully evaluated. Gompertz model has been shown to correctly describe the dynamics of cumulative confirmed cases, since it is characterized by a decrease in growth rate showing the effect of control measures. Thus, it provides a way to systematically quantify the Covid-19 spreading velocity and it allows short-term predictions and longer-term estimations. This model has been employed to fit the cumulative cases of Covid-19 from several European countries. Results show that there are systematic differences in spreading velocity among countries. The model predictions provide a reliable picture of the short-term evolution in countries that are in the initial stages of the Covid-19 outbreak, and may permit researchers to uncover some characteristics of the long-term evolution. These predictions can also be generalized to calculate short-term hospital and intensive care units (ICU) requirements.

Effects of formalin preservation on invertebrate stable isotope values over decadal time scales

2012 ◽  
Vol 90 (11) ◽  
pp. 1320-1327 ◽  
Author(s):  
Michael D. Rennie ◽  
Ted Ozersky ◽  
David O. Evans
Keyword(s):  
Stable Isotope ◽  
Marine Invertebrate ◽  
Time Frame ◽  
Freshwater Invertebrates ◽  
Significant Difference ◽  
Formalin Preservation ◽  
Ecosystem Changes ◽  
Short Time ◽  
Control Samples

Stable isotope values derived from chemically preserved organisms are a valuable resource for documenting long-term ecosystem changes. However, isotopic correction factors of preservation effects applied to samples stored for decades are frequently based on studies lasting only months, assuming that the effects of preservation stabilize within a short time frame. Very few studies test this critical assumption. We validated this assumption for formalin-preserved invertebrate tissues, finding no significant difference between mean isotopic δ13C and δ15N values of material stored 1–15 years across taxa. Preservation effects were evaluated for Amphipoda, Chironomidae, Dreissenidae, Ephemeroptera, Gastropoda, Isopoda, Sphaeridae, Oligochaeta, and Trichoptera. On average, freshwater benthos δ13C was lower by approximately 2‰ after formalin fixation, whereas δ15N values were not different from control samples. Fixation effects were similar among taxa, but were more pronounced in Gastropoda and Sphaeridae for δ13C and in Trichoptera for δ15N. We reviewed the literature to show that preserved freshwater zooplankton δ13C were slightly but significantly lower relative to control samples (–0.2‰) and higher in δ15N (+0.25‰). The mean decline among marine invertebrate δ13C was greater than for freshwater invertebrates after 1+ years of formalin preservation, but effects on δ15N were not different between marine and freshwater invertebrates.

Repeatability of methane emission measurements in Australian beef cattle

2016 ◽  
Vol 56 (3) ◽  
pp. 213 ◽  
Author(s):  
K. A. Donoghue ◽  
T. Bird-Gardiner ◽  
P. F. Arthur ◽  
R. M. Herd ◽  
R. S. Hegarty
Keyword(s):  
Methane Production ◽  
Life Time ◽  
Time Frame ◽  
Phenotypic Correlations ◽  
Methane Production Rate ◽  
Short And Long Term ◽  
Time Periods ◽  
Time Frames ◽  
Methane Measurement

Records on 175 young Angus heifer and bull progeny from 46 sires, measured for methane production in respiration chambers, were used to evaluate the repeatability of methane measurement over short- and long-term periods. The traits assessed were dry matter intake (DMI), methane production rate (MPR), methane yield (MPR per unit DMI), and four residual methane (RMP) traits. The RMP traits were computed as actual MPR minus expected MPR, where the expected MPR for the first three RMP traits were calculated from three different published and widely used equations. The expected MPR for the fourth was computed by regressing MPR on DMI, using the data from the study. Animals underwent an initial (first) methane measurement test for 48 h, and one repeat methane measurement test up to 450 days after the first test. Repeat tests were classified into four different time periods: tested across consecutive days; re-tested within 60 days of first test; re-tested 61–120 days after first test; and re-tested 121–450 days after first test. Repeatabilities were calculated for all traits across all time periods, and phenotypic correlations for the same trait measured over time were obtained from bivariate analyses. Methane traits from tests conducted over consecutive days were highly repeatable (0.75–0.94) and highly phenotypically correlated (0.85–0.95). Repeatabilities from tests conducted within 60 days of the first test were moderate to high (0.59–0.91), whereas phenotypic correlations were, in general, moderate (0.30–0.44), with the exception of MPR (0.78). Results for both longer-term time periods (61–120 days and 121–450 days after the first test) were very similar, with low estimates of repeatabilities (0.16–0.27) and phenotypic correlations (0.12–0.27). Correlations between sire progeny means from the first and repeat methane test were moderate (0.46–0.77) for all traits except RMPR (0.19). Results from this study indicate that methane traits from tests conducted either on consecutive days or within a short-term time frame afterward (~60 days) are highly repeatable and highly phenotypically correlated. However, methane tests conducted over longer-term time frames are substantially, but consistently, less repeatable and are lowly phenotypically correlated, which indicates that multiple measures may be required to accurately record methane traits over the life time of an animal.

scholarly journals A critical evaluation of coastal erosion in Rio Grande do Sul, Southern Brazil

2004 ◽  
Vol 76 (3) ◽  
pp. 611-623 ◽  
Author(s):  
Sérgio R. Dillenburg ◽  
Luciana S. Esteves ◽  
Luiz J. Tomazelli
Keyword(s):  
Coastal Erosion ◽  
Critical Evaluation ◽  
Rio Grande ◽  
Published Data ◽  
Rio Grande Do Sul ◽  
Southern Half ◽  
Short And Long Term ◽  
Negative Balance ◽  
Short Time

Evidences of coastal erosion in Rio Grande do Sul have been obtained by three methods: (a) analysis of the long-term morphodynamics and stratigraphy of coastal barriers, (b) annual shoreline mapping using the Differential Global Positioning System (DGPS), and (c) local beach profile measurements. The first method reflects coastal erosion as continuity of the geological evolution in the last 5 ka, taking place mainly along the southern half of gentle coastal projections. The second method represents a shorter temporal scale and indicates that approximately 80% of the coast is eroding. Beach profiling has been measured in very few places that are distant from each other since the early 1990s; consequently, their results reflect local and very short time shoreline behavior. A critical evaluation of published data addressing coastal erosion in Rio Grande do Sul strongly suggests that short and long term negative balance on the sediment budget is the main cause of erosion along this coastline.

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