Use of thoracic ultrasound by physiotherapists: a scoping review of the literature

Background Use of diagnostic thoracic ultrasound (TUS) in medical professions to examine the pleura, lung parenchyma and diaphragm is gaining in popularity, however the ways in which physiotherapists are using TUS is unclear. Objective The aim of this scoping review is to gain an understanding of the emerging evidence base surrounding physiotherapy use of TUS to inform research and clinical practice. Data Sources A systematic search was conducted of the following databases: Cochrane, EPPI centre, PROSPERO, Medline, CINAHL, AMED, EMBASE, HMIC, and BNI. Study Selection Inclusion criteria: primary research reporting the use of diagnostic TUS; a physiotherapist as part of the study design or as the chief investigator; published in English. Synthesis Methods Data regarding demographics, design, type of conditions and anatomical structures investigated and profession leading the TUS of included papers were compiled in a tabular format. Results Of the 26 included papers, 9 studied healthy participants, 4 studied COPD and 4 studied critical care patients. Most papers (n=23) involved scanning the diaphragm. In 8 studies the physiotherapist operated the TUS. Limitations The paper selection process was performed by one author; with no cross-checking by another individual. Conclusion Use of TUS by physiotherapists is an emerging area in both diaphragm and lung diagnostics. A wide range of patient populations may benefit from physiotherapists using TUS. Papers in this review are heterogeneous making any generalisability difficult but does show its potential for varied uses. TUS is an innovative skill in the hands of physiotherapists, but more research is needed. Funding: National Institute of Health Research (NIHR): Internship programme – no involvement Contribution of the paper: Thoracic ultrasound is gaining popularity amongst physiotherapists. The diaphragm is the most investigated structure by physiotherapists. Physiotherapists use thoracic ultrasound on a broad range of pathologies and patient populations

Patchiness and Demographic Noise in Three Ecological Examples

Understanding the causes and effects of spatial aggregation is one of the most fundamental problems in ecology. Aggregation is an emergent phenomenon arising from the interactions between the individuals of the population, able to sense only -at most- local densities of their cohorts. Thus, taking into account the individual-level interactions and fluctuations is essential to reach a correct description of the population. Classic deterministic equations are suitable to describe some aspects of the population, but leave out features related to the stochasticity inherent to the discreteness of the individuals. Stochastic equations for the population do account for these fluctuation-generated effects by means of demographic noise terms but, owing to their complexity, they can be difficult (or, at times, impossible) to deal with. Even when they can be written in a simple form, they are still difficult to numerically integrate due to the presence of the "square-root" intrinsic noise. In this paper, we discuss a simple way to add the effect of demographic stochasticity to three classic, deterministic ecological examples where aggregation plays an important role. We study the resulting equations using a recently-introduced integration scheme especially devised to integrate numerically stochastic equations with demographic noise. Aimed at scrutinizing the ability of these stochastic examples to show aggregation, we find that the three systems not only show patchy configurations, but also undergo a phase transition belonging to the directed percolation universality class.Comment: 20 pages, 5 figures. To appear in J. Stat. Phy

A plasticity model for powder compaction processes incorporating particle deformation and rearrangement

This article is available open access through the publisher’s website at the link below. Copyright @ 2008 Elsevier Ltd.This paper develops a mechanistic model of granular materials that can be used with a commercial finite element package (ABAQUS). The model draws on the ideas of critical state soil mechanics and combines them with the theory of envelopes to develop an elasto-plastic model with a non-associated flow rule. The model incorporates both local deformation at the granule contacts, and rearrangement of the granules so that jointly they account for any bulk deformation. The mechanics of the model closely reflect the physicality of the material behaviour and the model parameters are closely linked (although not simplistically identical) to the characteristics of the granules. This not only gives an insight into the material behaviour, but also enables the model to be used to facilitate design of the material, its processing properties and, hence, component development. The model is used to simulate drained triaxial tests, settlement of a powder in a bin, and some examples of die pressing. Simulations are compared with experimental data and with predictions obtained using other models

Branching and annihilating Levy flights

We consider a system of particles undergoing the branching and annihilating reactions A -> (m+1)A and A + A -> 0, with m even. The particles move via long-range Levy flights, where the probability of moving a distance r decays as r^{-d-sigma}. We analyze this system of branching and annihilating Levy flights (BALF) using field theoretic renormalization group techniques close to the upper critical dimension d_c=sigma, with sigma<2. These results are then compared with Monte-Carlo simulations in d=1. For sigma close to unity in d=1, the critical point for the transition from an absorbing to an active phase occurs at zero branching. However, for sigma bigger than about 3/2 in d=1, the critical branching rate moves smoothly away from zero with increasing sigma, and the transition lies in a different universality class, inaccessible to controlled perturbative expansions. We measure the exponents in both universality classes and examine their behavior as a function of sigma.Comment: 9 pages, 4 figure

Large negative velocity gradients in Burgers turbulence

We consider 1D Burgers equation driven by large-scale white-in-time random force. The tails of the velocity gradients probability distribution function (PDF) are analyzed by saddle-point approximation in the path integral describing the velocity statistics. The structure of the saddle-point (instanton), that is velocity field configuration realizing the maximum of probability, is studied numerically in details. The numerical results allow us to find analytical solution for the long-time part of the instanton. Its careful analysis confirms the result of [Phys. Rev. Lett. 78 (8) 1452 (1997) [chao-dyn/9609005]] based on short-time estimations that the left tail of PDF has the form ln P(u_x) \propto -|u_x|^(3/2).Comment: 10 pages, RevTeX, 10 figure