scholarly journals Investigating Disease Spread between Two Assessment Dates with Permutation Tests on a Lattice

2005 ◽  
Vol 95 (12) ◽  
pp. 1453-1461 ◽  
Author(s):  
Gaël Thébaud ◽  
Nathalie Peyrard ◽  
Sylvie Dallot ◽  
Agnès Calonnec ◽  
Gérard Labonne
Keyword(s):  
Binary Data ◽  
Prior Information ◽  
Mechanistic Model ◽  
Disease Status ◽  
Disease Spread ◽  
Spatial Structures ◽  
Monte Carlo Test ◽  
Point Patterns ◽  
Causes Of Disease ◽  
Insight Into

Mapping and analyzing the disease status of individual plants within a study area at successive dates can give insight into the processes involved in the spread of a disease. We propose a permutation method to analyze such spatiotemporal maps of binary data (healthy or diseased plants) in regularly spaced plantings. It requires little prior information on the causes of disease spread and handles missing plants and censored data. A Monte Carlo test is used to assess whether the location of newly diseased plants is independent of the location of previously diseased plants. The test takes account of the significant spatial structures at each date in order to separate nonrandomness caused by the structure at one date from nonrandomness caused by the dependence between newly diseased plants and previously diseased plants. If there is a nonrandom structure at both dates, independent patterns are simulated by randomly shifting the entire pattern observed at the second date. Otherwise, independent patterns are simulated by randomly reallocating the positions of one group of diseased plants. Simulated and observed patterns of disease are then compared through distance-based statistics. The performance of the method and its robustness are evaluated by its ability to accurately identify simulated independent and dependent bivariate point patterns. Additionally, two realworld spatiotemporal maps with contrasting disease progress illustrate how the tests can provide valuable clues about the processes of disease spread. This method can supplement biological investigations and be used as an exploratory step before developing a specific mechanistic model.

scholarly journals Insights into Sensing of Murine Retroviruses

Viruses ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 836
Author(s):  
Eileen A. Moran ◽  
Susan R. Ross
Keyword(s):  
Immune Response ◽  
Immune System ◽  
Nucleic Acid ◽  
Adaptive Immunity ◽  
Innate Immune System ◽  
Innate Immune ◽  
Genetic Tool ◽  
Causes Of Disease ◽  
Retrovirus Infection ◽  
Insight Into

Retroviruses are major causes of disease in animals and human. Better understanding of the initial host immune response to these viruses could provide insight into how to limit infection. Mouse retroviruses that are endemic in their hosts provide an important genetic tool to dissect the different arms of the innate immune system that recognize retroviruses as foreign. Here, we review what is known about the major branches of the innate immune system that respond to mouse retrovirus infection, Toll-like receptors and nucleic acid sensors, and discuss the importance of these responses in activating adaptive immunity and controlling infection.

scholarly journals Childhood asthma and risk factors

2010 ◽  
Vol 63 (7-8) ◽  
pp. 516-521 ◽  
Author(s):  
Radmila Ljustina-Pribic ◽  
Slobodanka Petrovic ◽  
Jelena Tomic
Keyword(s):  
Risk Factors ◽  
Childhood Asthma ◽  
Epidemiological Studies ◽  
Supporting Evidence ◽  
Prognosis Factors ◽  
History Of Disease ◽  
Heterogeneous Nature ◽  
Causes Of Disease ◽  
History Of ◽  
Insight Into

Introduction. This article summarizes the contribution of epidemiology to the understanding of childhood asthma. The first task in epidemiology is to determine prevalence and incidence of any disease. Prevalence. Epidemiological investigations are aimed at evaluating hypotheses about causes of disease by defining demographic characteristics of a certain population as well as by determining possible effects of environmental factors. In spite of some limitations, data obtained by epidemiological investigations have been valuable in confirming both the increasing incidence of asthma and the differences in prevalence in certain population groups. The observance of this phenomenon has led to much speculation and a lot of attempts to identify the reasons behind the rising prevalence. Risk factors. Epidemiological studies have identified risk factors for the development of childhood asthma and provided insight into natural history of disease and prognosis. Factors ranging from increased numbers of immunizations to increased air pollution have been suggested, but subsequent analysis has failed to provide the supporting evidence to implicate most of these possibilities. The concept known as the hygiene hypothesis has gained some support from epidemiological studies. Conclusion. The development of asthma as well as its severity are affected by numerous factors and their interactions can be explained by the heterogeneous nature of this disease.

Radical yields in DNA exposed to ionizing radiation: Role of energy and charge transfer

1990 ◽  
Vol 68 (9) ◽  
pp. 962-966 ◽  
Author(s):  
John H. Miller ◽  
Charles E. Swenberg
Keyword(s):  
Charge Transfer ◽  
Ionizing Radiation ◽  
Mechanistic Model ◽  
Experimental Studies ◽  
High Mobility ◽  
Orientation Dependence ◽  
Model Calculations ◽  
Insight Into ◽  
High Linear Energy Transfer

Theoretical and experimental studies of free-radical yields in oriented DNA samples exposed to ionizing radiation with high linear energy transfer at 77 K are discussed. The dependence of radical yields on the orientation of DNA chains relative to the particle flux is being investigated to gain insight into the role of intramolecular energy and charge transfer processes in radical production and decay. Model calculations based on a thermal-spike approximation are presented and their limitations for predicting the orientation dependence of radical yields observed after neutron irradiation (see C. M. Arroyo et al. Int. J. Radiat. Biol. 50, 789 (1986)) are discussed. A more mechanistic model based on the high mobility of excess electrons in hydrated DNA (D. van Lith et al. J. Chem. Soc. Faraday Trans. 1, 82, 2933 (1986)) is outlined.

scholarly journals Density Estimation of Spatio-temporal Point Patterns Using Moran's Statistic

2018 ◽  
Vol 7 (2) ◽  
pp. 80
Author(s):  
Jennifer L. Lorio ◽  
Norou Diawara ◽  
Lance A. Waller
Keyword(s):  
Infectious Disease ◽  
Monte Carlo Simulation ◽  
Monte Carlo ◽  
Poisson Process ◽  
Common Factor ◽  
Disease Spread ◽  
Point Patterns ◽  
Rate Of Increase ◽  
Spatio Temporal ◽  
Over Time

Moran's Index is a statistic that measures spatial autocorrelation, quantifying the degree of dispersion (or spread) of objects in space. When investigating data in an area, a single Moran statistic may not give a sufficient summary of the autocorrelation spread. However, by partitioning the area and taking the Moran statistic of each subarea, we discover patterns of the local neighbors not otherwise apparent. In this paper, we consider the model of the spread of an infectious disease, incorporate time factor, and simulate a multilevel Poisson process where the dependence among the levels is captured by the rate of increase of the disease spread over time, steered by a common factor in the scale. The main consequence of our results is that our Moran statistic is calculated from an explicit algorithm in a Monte Carlo simulation setting. Results are compared to Geary's statistic and estimates of parameters under Poisson process are given.

Microvascular fluid flow in ex vivo and engineered lungs

2021 ◽  
Author(s):  
Micha Sam Brickman Raredon ◽  
Alexander James Engler ◽  
Yifan Yuan ◽  
Allison Marie Greaney ◽  
Laura E. Niklason
Keyword(s):  
Fluid Flow ◽  
Ex Vivo ◽  
Mechanistic Model ◽  
Culture Fluid ◽  
Pulmonary Tissue ◽  
Capillary Recruitment ◽  
Pulmonary Parenchyma ◽  
Barrier Resistance ◽  
Microvascular Recruitment ◽  
Insight Into

In recent years, it has become common to experiment with ex vivo perfused lungs for organ transplantation, and to attempt regenerative pulmonary engineering using decellularized lung matrices. However, our understanding of the physiology of ex vivo organ perfusion is imperfect: it is not currently well understood how decreasing microvascular barrier affects the perfusion of pulmonary parenchyma. Additionally, protocols for lung perfusion and organ culture fluid-handling are far from standardized, with widespread variation on both basic methods and on ideally controlled parameters. To address both of these deficits, a robust, non-invasive, and mechanistic model is needed which is able to predict microvascular resistance and permeability in perfused lungs while providing insight into capillary recruitment. Although validated mathematical models exist for fluid flow in native pulmonary tissue, previous models generally assume minimal intravascular leak from artery to vein and do not assess capillary bed recruitment. Such models are difficult to apply to both ex vivo lung perfusions, in which edema can develop over time and microvessels can become blocked, and to decellularized ex vivo organomimetic cultures, in which microvascular recruitment is variable and arterially-perfused fluid enters into the alveolar space. Here, we develop a mathematical model of pulmonary microvascular fluid flow which is applicable in both instances, and we apply our model to data from native, decellularized, and regenerating lungs under ex vivo perfusion. The results provide substantial insight into microvascular pressure-flow mechanics, while producing previously unknown output values for tissue-specific capillary-alveolar hydraulic conductivity, microvascular recruitment, and total organ barrier resistance.

Patterns of disease and severity in bipolar disorder: Retrospective data from a large multinational longitudinal study (WAVE-bd)

2011 ◽  
Vol 26 (S2) ◽  
pp. 258-258
Author(s):  
E. Vieta ◽  
M.L. Figueira ◽  
F. Bellivier ◽  
D. Souery ◽  
E. Blasco-Colmenares ◽  
...  
Keyword(s):  
Bipolar Disorder ◽  
Longitudinal Study ◽  
Data Collection ◽  
Total Population ◽  
Mood State ◽  
Disease Status ◽  
Retrospective Data ◽  
Retrospective Data Collection ◽  
Insight Into

IntroductionThe Wide AmbispectiVE study of the clinical management and burden of bipolar disorder (BD) (WAVE-bd; NCT01062607) is ongoing to address limitations of longitudinal BD studies to-date focused on single disease phases or treatment.Aim/ObjectiveTo describe baseline bipolar mood state and severity in a cohort of patients with BD.MethodsMultinational, multicentre, non-interventional, longitudinal study of patients diagnosed with BD-I or BD-II with ≥1 mood event in the preceding 12 months (retrospective data collection from index mood event to enrolment, followed by 9-14 months’ prospective follow-up). Site and patient selection provided a sample representative of bipolar populations. The study includes descriptive analyses of demographics, diagnosis and medical history.Results2880 patients (mean age 46.5 years [SD: 13.3]; 62.0% female) were recruited March to September 2010: 1989 (69.1%) BD-I and 891 (30.9%) BD-II. Time (years) from first symptoms to diagnosis was 2.9 [SD: 6.6] (BD-I) and 4.4 [SD: 8.0] (BD-II). Of the total population, 20.8% lived alone (13.9% BD-I, 6.9% BD-II), 36.7% were employed (24.0% BD-I, 12.7% BD-II) and 13.3% unemployed (9.5% BD-I, 3.8% BD-II). Disease status at inclusion (BD-I, BD-II, respectively [mild, moderate, severe]) included hypomania (7.9% [67.7%, 31.0%, 1.3%], 6.5% [70.7%, 29.3%, 0%]), mania (7.1% [26.1%, 47.2%, 26.8%], 0%), euthymia (58.6%, 60.3%), depression (19.7% [38.8%, 47.7%, 13.5%], 31.1% [41.2%, 46.9%, 11.9%]) and mixed (5.7% [30.1%, 46.9%, 23.0%], 0%).ConclusionsThis ongoing study provides detailed insight into a large BD population, showing the majority with euthymia and an important proportion with depression both in BD-I and BD-II patients.

scholarly journals Speed and strength of an epidemic intervention

2020 ◽  
Author(s):  
Jonathan Dushoff ◽  
Sang Woo Park
Keyword(s):  
Growth Rate ◽  
Exponential Growth ◽  
Intervention Strategy ◽  
Disease Spread ◽  
Reproductive Number ◽  
Mathematical Framework ◽  
Exponential Growth Rate ◽  
Strength Based ◽  
Immunodeficiency Virus ◽  
Insight Into

AbstractAn epidemic can be characterized by its speed (i.e., the exponential growth rate r) and strength (i.e., the reproductive number ℛ). Disease modelers have historically placed much more emphasis on strength, in part because the effectiveness of an intervention strategy is typically evaluated on this scale. Here, we develop a mathematical framework for this classic, strength-based paradigm and show that there is a corresponding speed-based paradigm which can provide complementary insights. In particular, we note that r = 0 is a threshold for disease spread, just like ℛ = 1, and show that we can measure the speed and strength of an intervention on the same scale as the speed and strength of an epidemic, respectively. We argue that, just as the strength-based paradigm provides the clearest insight into certain questions, the speed-based paradigm provides the clearest view in other cases. As an example, we show that evaluating the prospects of “test-and-treat” interventions against the human immunodeficiency virus (HIV) can be done more clearly on the speed than strength scale, given uncertainty in the proportion of HIV spread that happens early in the course of infection. We suggest that disease modelers should avoid over-emphasizing the reproductive number at the expense of the exponential growth rate, but instead look at these as complementary measures.

scholarly journals Noise Issues Prevailing in Various Types of Medical Images

2018 ◽  
Vol 11 (3) ◽  
pp. 1227-1237 ◽  
Author(s):  
Bhawna Goyal ◽  
Ayush Dogra ◽  
Sunil Agrawal ◽  
B.S. Sohi
Keyword(s):  
Remote Sensing ◽  
Medical Imaging ◽  
Image Denoising ◽  
Prior Information ◽  
Medical Images ◽  
Natural Images ◽  
Imaging Modalities ◽  
Basic Definition ◽  
Remote Sensing Images ◽  
Insight Into

The current literature documents a plethora of image denoising techniques in the fields of medical imaging, remote sensing, biometrics, surveillance and vegetation mapping. Therefore it is important to have brief insight into various types of noises in different type of images, for instance medical images, remote sensing images and natural images. This article encompasses the basic definition, history, usage and type of noise affecting some of the major types of imaging modalities. Besides this a brief discussion on the type of noise prevailing in remote sensing and natural images is also given. While designing an effective image denoising algorithm, one needs to be acquainted with the prior information about the noise prevalent in various types of images. Further, a brief idea about the basic principle, outlook, contrast levels and application of medical imaging modalities has also been presented in the context of this article.­­­­­­

scholarly journals Z-scores unite >70 pairwise indices of ecological similarity and association for binary data

2019 ◽  
Author(s):  
Petr Keil
Keyword(s):  
Binary Data ◽  
Jaccard Index ◽  
Z Score ◽  
Point Patterns ◽  
The Face ◽  
Z Scores ◽  
The Right ◽  
Null Expectation ◽  
Selection Of ◽  
Better Than

AbstractPairwise ecological resemblance, which includes compositional similarity between sites (beta diversity), or associations between species (co-occurrence), can be measured by >70 indices. Classical examples for presence-absence data are Jaccard index or C-score. These can be expressed using contingency table matching components a, b, c and d - the joint presences, presences at only one site/species, and joint absences. Using simulations of point patterns for two species with known magnitude of association, I demonstrate that most of the indices describe this simulated association almost identically, as long as they are calculated as a Z-score, i.e. as deviation of the index from a null expectation. Further, I show that Z-scores estimated resemblance better than raw forms of the indices, particularly in the face of confounding effects of spatial scale and conspecific aggregation. Finally, I show that any single of the matching components, when expressed as Z-score, can be used as an index that performs as good as the classical indices; this also includes joint absences. All this simplifies selection of the “right” resemblance index, it underscores the advantage of expressing resemblance as deviation from a null expectation, and it revives the potential of joint absences as a meaningful ecological quantity.

scholarly journals Monitoring of rheumatoid arthritis: a patient survey on disease insight and possible added value of an innovative inflammation monitoring device

2021 ◽  
Author(s):  
Ria Wolkorte ◽  
Lieke Heesink ◽  
Michelle M. A. Kip ◽  
Hendrik Koffijberg ◽  
Monique Tabak ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Outpatient Clinic ◽  
Disease Status ◽  
Added Value ◽  
Inflammatory Activity ◽  
Current Status ◽  
Monitoring Device ◽  
Spectral Transmission ◽  
Monitoring Process ◽  
Insight Into

AbstractTo enable patients with rheumatoid arthritis (RA) and their healthcare professionals to choose the optimal treatment, it is crucial to accurately assess the current state of inflammatory activity. The objectives of this study were to (1) investigate the perspective of RA patients on their insight into the current status of their disease, and to (2) investigate the patients’ perspective on the possible added value of a monitoring device based on optical spectral transmission—called the HandScan—that measures the location and severity of joint inflammation. A survey was distributed online among patients with RA in the Netherlands. Four-hundred and eight patients with RA completed the survey. Of these, 298 (73%) felt they have sufficient insight into their current disease status. Most respondents perceived either a large (n = 242; 59%) or small (n = 148; 36%) added value of the HandScan in their monitoring process, mostly because the device provides additional knowledge on the presence of inflammation. This perceived added value was higher for respondents experienced with the device (n = 46; p = .04). Respondents preferred monitoring with the device on every (n = 192; 47%) or most (n = 171; 42%) visits to the outpatient clinic, or even more often than on every visit (n = 17; 4%). Monitoring RA using an optical spectral transmission device is seen by patients as a possibly valuable addition to the monitoring process of inflammatory activity during visits to an outpatient clinic. Their main reason was that the device can increase insight into their current disease status. More insight may support patients in discussing treatment options with their rheumatologist.

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