706 research outputs found
Cost-Effective Screening for Breast Cancer Worldwide: Current State and Future Directions
Affordability of healthcare is highly limited by its skyrocketing cost. Access to screening and diagnostic medical equipment and medicine in developing countries is inadequate for the majority of the population. There is a tremendous worldwide need to detect breast cancer at its earliest stage. These needs must be balanced by the ability of countries to provide breast cancer screening technology to their populations. We reviewed the diagnostic accuracy, procedure cost and cost-effectiveness of currently available technique for breast screening and diagnosis including clinical breast examination, mammography, ultrasound, magnetic resonance imaging, biopsy and a new modality for cancer diagnostics termed elasticity imaging that has emerged in the last decade. Clinical results demonstrate that elasticity imaging even in its simplest and least sophisticated versions, like tactile imaging, has significant diagnostic potential comparable and exceeding that of conventional imaging techniques. In view of many countries with limited resources, effective yet less expensive modes of screening must be considered worldwide. The tactile imaging is one method that has the potential to provide cost-effective breast cancer screening and diagnostics
An Estimate of the Vibrational Frequencies of Spherical Virus Particles
The possible normal modes of vibration of a nearly spherical virus particle
are discussed. Two simple models for the particle are treated, a liquid drop
model and an elastic sphere model. Some estimates for the lowest vibrational
frequency are given for each model. It is concluded that this frequency is
likely to be of the order of a few GHz for particles with a radius of the order
of 50 nm.Comment: 6 pages, 1 figur
Atividades digitais através do Edilim no 1º ciclo do ensino básico : resultados de uma investigação na prática de ensino supervisionada
As TIC fazem parte fundamental da nossa vida sendo indispensáveis para as atividades diárias de cada cidadão. Naturalmente, no sistema educativo as TIC também transformam o dia a dia na comunidade educativa. Neste sentido, a formação dos jovens em TIC para adquirirem competências digitais é um aspeto fundamental para os preparar para a sociedade atual e que deve ser inicializada através da sua utilização em contexto de sala de aula. O Relatório de Estágio pretendeu averiguar as potencialidades da utilização das TIC e o impacto, em particular, da implementação de um software de autor «EdiLim» através dos seguintes objetivos: promover a utilização de recursos digitais nas aprendizagens do 1.° Ciclo; identificar qual a utilização das TIC que os professores fazem no contexto de sala de aula; implementar atividades pedagógicas com atividades através do EdiLim; avaliar o contributo para as aprendizagens através da utilização do EdiLim. Esta investigação foi desenvolvida no âmbito da Prática de Ensino Supervisionada no 1º Ciclo do Ensino Básico (PES1CEB), no 2º ano do Mestrado em Educação Pré-Escolar e Ensino do 1º Ciclo do Ensino Básico. A turma era constituída por 22 alunos com idades compreendidas entre os 9 e os 10 anos. A investigação assumiu um caráter qualitativo no qual se realizou uma abordagem de estudo de caso e de investigação-ação. O principal instrumento de recolha de dados consistiu na observação participada com recurso a registo fotográfico e notas de campo, tendo como participantes, para além da investigadora e dos alunos, a «Orientadora Cooperante» e o «Par Pedagógico». Houve ainda necessidade de realizar inquéritos por questionários aos alunos e entrevistas semiestruturadas à «Orientadora Cooperante» e a um professor do 1º CEB da Instituição, como forma de conhecer a opinião dos inquiridos e entrevistados face à utilização das TIC e de softwares educativos como recurso no Ensino Básico. Em suma, os resultados da investigação, através da triangulação de dados possibilitaram a perceção de que a utilização do EdiLim veio promover maiores e melhores níveis de motivação dos alunos, favorecendo o processo de ensino e de aprendizagem.info:eu-repo/semantics/publishedVersio
Overview of AuTexTification at IberLEF 2023: Detection and Attribution of Machine-Generated Text in Multiple Domains
This paper presents the overview of the AuTexTification shared task as part
of the IberLEF 2023 Workshop in Iberian Languages Evaluation Forum, within the
framework of the SEPLN 2023 conference. AuTexTification consists of two
subtasks: for Subtask 1, participants had to determine whether a text is
human-authored or has been generated by a large language model. For Subtask 2,
participants had to attribute a machine-generated text to one of six different
text generation models. Our AuTexTification 2023 dataset contains more than
160.000 texts across two languages (English and Spanish) and five domains
(tweets, reviews, news, legal, and how-to articles). A total of 114 teams
signed up to participate, of which 36 sent 175 runs, and 20 of them sent their
working notes. In this overview, we present the AuTexTification dataset and
task, the submitted participating systems, and the results.Comment: Accepted at SEPLN 202
Chemical Ablation Of Purkinje Fibers Diminishes Spontaneous Activity In A Rat Model Of Regional Ischemia And Reperfusion
Generation and escape of local waves from the boundary of uncoupled cardiac tissue
We aim to understand the formation of abnormal waves of activity from
myocardial regions with diminished cell-to-cell coupling. In route to this
goal, we studied the behavior of a heterogeneous myocyte network in which a
sharp coupling gradient was placed under conditions of increasing network
automaticity. Experiments were conducted in monolayers of neonatal rat
cardiomyocytes using heptanol and isoproterenol as means of altering
cell-to-cell coupling and automaticity respectively. Experimental findings were
explained and expanded using a modified Beeler-Reuter numerical model. The data
suggests that the combination of a heterogeneous substrate, a gradient of
coupling and an increase in oscillatory activity of individual cells creates a
rich set of behaviors associated with self-generated spiral waves and ectopic
sources. Spiral waves feature a flattened shape and a pin-unpin drift type of
tip motion. These intercellular waves are action-potential based and can be
visualized with either voltage or calcium transient measurements. A source/load
mismatch on the interface between the boundary and well-coupled layers can lock
wavefronts emanating from both ectopic sources and rotating waves within the
inner layers of the coupling gradient. A numerical approach allowed us to
explore how: i) the spatial distribution of cells, ii) the amplitude and
dispersion of cell automaticity, iii) and the speed at which the coupling
gradient moves in space, affects wave behavior, including its escape into
well-coupled tissue.Comment: 28 pages, 10 figures, submitted to Biophysical Journa
Bisphenol A exposure and cardiac electrical conduction in excised rat hearts
BACKGROUND:
Bisphenol A (BPA) is used to produce polycarbonate plastics and epoxy resins that are widely used in everyday products, such as food and beverage containers, toys and medical devices. Human biomonitoring studies have suggested that a large proportion of the population may be exposed to BPA. Recent epidemiological studies have reported correlations between increased BPA urinary concentrations and cardiovascular disease; yet the direct effects of BPA on the heart are unknown. OBJECTIVES:
The goal of our studies was to measure BPA\u27s effect (0.1-100 μM) on cardiac impulse propagation ex vivo, using excised whole hearts from adult rats. METHODS:
We measured atrial and ventricular activation times during sinus and paced rhythms using epicardial electrodes and optical mapping of transmembrane potential. Atrioventricular activation intervals and epicardial conduction velocities were computed using recorded activation times. RESULTS:
Cardiac BPA exposure resulted in prolonged PR segment and decreased epicardial conduction velocity (0.1 - 100 μM), prolonged action potential duration (1 - 100 μM) and delayed atrioventricular conduction (10 - 100 μM). Importantly, these effects were observed after acute exposure (≤ 15 min), underscoring the potential detrimental effects of continuous BPA exposure. The highest BPA concentration used (100 μM) resulted in prolonged QRS intervals, dropped ventricular beats and eventually resulted in complete heart block. CONCLUSIONS:
Our results show that acute BPA exposure slows electrical conduction in excised hearts from female rats. These findings emphasize the importance of examining BPA\u27s effect on heart electrophysiology and determining whether chronic in vivo exposure can cause/exacerbate conduction abnormalities in patients with pre-existing heart conditions and other high-risk populations
Evolution of spiral and scroll waves of excitation in a mathematical model of ischaemic border zone
Abnormal electrical activity from the boundaries of ischemic cardiac tissue
is recognized as one of the major causes in generation of ischemia-reperfusion
arrhythmias. Here we present theoretical analysis of the waves of electrical
activity that can rise on the boundary of cardiac cell network upon its
recovery from ischaemia-like conditions. The main factors included in our
analysis are macroscopic gradients of the cell-to-cell coupling and cell
excitability and microscopic heterogeneity of individual cells. The interplay
between these factors allows one to explain how spirals form, drift together
with the moving boundary, get transiently pinned to local inhomogeneities, and
finally penetrate into the bulk of the well-coupled tissue where they reach
macroscopic scale. The asymptotic theory of the drift of spiral and scroll
waves based on response functions provides explanation of the drifts involved
in this mechanism, with the exception of effects due to the discreteness of
cardiac tissue. In particular, this asymptotic theory allows an extrapolation
of 2D events into 3D, which has shown that cells within the border zone can
give rise to 3D analogues of spirals, the scroll waves. When and if such scroll
waves escape into a better coupled tissue, they are likely to collapse due to
the positive filament tension. However, our simulations have shown that such
collapse of newly generated scrolls is not inevitable and that under certain
conditions filament tension becomes negative, leading to scroll filaments to
expand and multiply leading to a fibrillation-like state within small areas of
cardiac tissue.Comment: 26 pages, 13 figures, appendix and 2 movies, as accepted to PLoS ONE
2011/08/0
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