The statistical building blocks of animal movement simulations.

Animal movement plays a key role in many ecological processes and has a direct influence on an individual's fitness at several scales of analysis (i.e., next-step, subdiel, day-by-day, seasonal).

A comparison of COVID-19 outbreaks across US Combined Statistical Areas using new methods for estimating R and social distancing behaviour.

We investigated the initial outbreak rates and subsequent social distancing behaviour over the initial phase of the COVID-19 pandemic across 29 Combined Statistical Areas (CSAs) of the United States. We used the Numerus Model Builder Data and Simulation Analysis (NMB-DASA) web application to fit the exponential phase of a SCLAIV+D (Susceptible, Contact, Latent, Asymptomatic infectious, symptomatic Infectious, Vaccinated, Dead) disease classes model to outbreaks, thereby allowing us to obtain an estimate of the basic reproductive number R for each CSA. Values of R ranged from 1.

Simulation applications to support teaching and research in epidemiological dynamics.

Background: An understanding of epidemiological dynamics, once confined to mathematical epidemiologists and applied mathematicians, can be disseminated to a non-mathematical community of health care professionals and applied biologists through simple-to-use simulation applications. We used Numerus Model Builder RAMP (Runtime Alterable Model Platform) technology, to construct deterministic and stochastic versions of compartmental SIR (Susceptible, Infectious, Recovered with immunity) models as simple-to-use, freely available, epidemic simulation application programs.

Results: We take the reader through simulations used to demonstrate the following concepts: 1) disease prevalence curves of unmitigated outbreaks have a single peak and result in epidemics that 'burn' through the population to become extinguished when the proportion of the susceptible population drops below a critical level; 2) if immunity in recovered individuals wanes sufficiently fast then the disease persists indefinitely as an endemic state, with possible dampening oscillations following the initial outbreak phase; 3) the steepness and initial peak of the prevalence curve are influenced by the basic reproductive value R, which must exceed 1 for an epidemic to occur; 4) the probability that a single infectious individual in a closed population (i.

A runtime alterable epidemic model with genetic drift, waning immunity and vaccinations.

We present methods for building a Java Runtime-Alterable-Model Platform (RAMP) of complex dynamical systems. We illustrate our methods by building a multivariant SEIR (epidemic) RAMP. Underlying our RAMP is an individual-based model that includes adaptive contact rates, pathogen genetic drift, waning and cross-immunity.

Modeling the population effects of escape mutations in SARS-CoV-2 to guide vaccination strategies.

SARS-Cov-2 escape mutations (EM) have been detected and are spreading. Vaccines may need adjustment to respond to these or future mutations. We designed a population level model integrating both waning immunity and EM.

A versatile web app for identifying the drivers of COVID-19 epidemics.

Background: No versatile web app exists that allows epidemiologists and managers around the world to comprehensively analyze the impacts of COVID-19 mitigation. The http://covid-webapp.numerusinc.

Adequacy of SEIR models when epidemics have spatial structure: Ebola in Sierra Leone.

Dynamic SEIR (Susceptible, Exposed, Infectious, Removed) compartmental models provide a tool for predicting the size and duration of both unfettered and managed outbreaks-the latter in the context of interventions such as case detection, patient isolation, vaccination and treatment. The reliability of this tool depends on the validity of key assumptions that include homogeneity of individuals and spatio-temporal homogeneity. Although the SEIR compartmental framework can easily be extended to include demographic (e.

Modeling epidemics: A primer and Numerus Model Builder implementation.

Epidemiological models are dominated by compartmental models, of which SIR formulations are the most commonly used. These formulations can be continuous or discrete (in either the state-variable values or time), deterministic or stochastic, or spatially homogeneous or heterogeneous, the latter often embracing a network formulation. Here we review the continuous and discrete deterministic and discrete stochastic formulations of the SIR dynamical systems models, and we outline how they can be easily and rapidly constructed using Numerus Model Builder, a graphically-driven coding platform.

An Agent-Based Model of School Closing in Under-Vacccinated Communities During Measles Outbreaks.

The winter 2014-15 measles outbreak in the US represents a significant crisis in the emergence of a functionally extirpated pathogen. Conclusively linking this outbreak to decreases in the measles/mumps/rubella (MMR) vaccination rate (driven by anti-vaccine sentiment) is critical to motivating MMR vaccination. We used the NOVA modeling platform to build a stochastic, spatially-structured, individual-based SEIR model of outbreaks, under the assumption that ≈ 7 for measles.

Sympatric speciation in structureless environments.

Background: Darwin and the architects of the Modern Synthesis found sympatric speciation difficult to explain and suggested it is unlikely to occur. Increasingly, evidence over the past few decades suggest that sympatric speciation can occur under ecological conditions that require at most intraspecific competition for a structured resource. Here we used an individual-based population model with variable foraging strategies to study the evolution of mating behavior among foraging strategy types.

Panmictic and Clonal Evolution on a Single Patchy Resource Produces Polymorphic Foraging Guilds.

We develop a stochastic, agent-based model to study how genetic traits and experiential changes in the state of agents and available resources influence individuals' foraging and movement behaviors. These behaviors are manifest as decisions on when to stay and exploit a current resource patch or move to a particular neighboring patch, based on information of the resource qualities of the patches and the anticipated level of intraspecific competition within patches. We use a genetic algorithm approach and an individual's biomass as a fitness surrogate to explore the foraging strategy diversity of evolving guilds under clonal versus hermaphroditic sexual reproduction.

Tactics and strategies for managing Ebola outbreaks and the salience of immunization.

We present a stochastic transmission chain simulation model for Ebola viral disease (EVD) in West Africa, with the salutary result that the virus may be more controllable than previously suspected. The ongoing tactics to detect cases as rapidly as possible and isolate individuals as safely as practicable is essential to saving lives in the current outbreaks in Guinea, Liberia, and Sierra Leone. Equally important are educational campaigns that reduce contact rates between susceptible and infectious individuals in the community once an outbreak occurs.

Stent-graft limb deployment in the external iliac artery increases the risk of limb occlusion following endovascular AAA repair.

Purpose: To assess whether deployment of an endograft limb in the external iliac artery (EIA) increases the rate of limb occlusion following endovascular aneurysm repair (EVAR).

Methods: Interrogation of a prospectively maintained database identified 661 patients (596 men; median age 73 years, range 37-93) with infrarenal abdominal aortic aneurysm who underwent EVAR between 1996 and 2010 using Zenith stent-grafts predominately. Of these, 567 patients [56 (9.

Endovascular repair of the aorta and aortic arch arteries damaged during mediastinoscopy.

Despite advances in imaging techniques, mediastinoscopy remains an important tool for the staging of the mediastinum in non-small cell lung cancer and diagnosing lymphoma with mediastinal adenopathy. Injury to the arterial system during mediastinoscopy is infrequent but a potentially fatal complication. We report three cases of injury to the aorta and supra-aortic arteries sustained during mediastinoscopy.

Acute rupture of a fibromuscular dysplasia related renal artery aneurysm: emergency treatment with a covered stent.

We report the successful exclusion of a ruptured left renal artery aneurysm as a first presentation of fibromuscular dysplasia in a haemodynamically unstable 57-year-old man. The aneurysm was repaired in an emergency setting by deployment of a covered stent with a satisfactory result. Follow-up computed tomography confirmed successful exclusion of the aneurysm.

Use of a remotely steerable "robotic" catheter in a branched endovascular aortic graft.

We report the use of a remotely steerable catheter to treat kinked renal bridging stents 8 months after branched endovascular repair of a type III thoracoabdominal aortic aneurysm. Conventional techniques using single, coaxial, and manually steerable sheaths proved too unstable to provide the support required to pass a wire against resistance through the kinked stent. A remotely steerable "robotic" catheter provided sufficient precision and stability to cross the kink and reline it with an additional stent, restoring renal perfusion.

Percutaneous closure and "push-pull" technique to repair arterial lead and sheath placement complicating cardiac resynchronization therapy.

We present a case of inadvertent subclavian arterial puncture and lead placement to the left ventricle in a patient undergoing cardiac resynchronization therapy. We describe the use of a "push-pull" technique within an arterial setting to allow removal of the lead, while maintaining access through the same puncture to allow an arterial-closure device to then seal the artery at this site. As a result of this percutaneous approach, the patient avoided the need for a vascular surgical procedure.

Image-guided therapies in orthopedic oncology.

The treatment of patients who have malignancies of bone often require multidisciplinary care. The aim of this review is to outline percutaneous techniques that may be useful for the diagnosis and treatment of these patients. In particular, the existing procedures of percutaneous biopsy, alcoholization (ethanol ablation), vertebroplasty, kyphoplasty, osteoplasty, radiofrequency ablation, laser photocoagulation, and vascular embolization are reviewed.