Didactic Paper Research Articles

Modeling cancer’s ecological and evolutionary dynamics

In this didactic paper, we present a theoretical modeling framework, called the G-function, that integrates both the ecology and evolution of cancer to understand oncogenesis. The G-function has been used in evolutionary ecology, but has not been widely applied to problems in cancer. Here, we build the G-function framework from fundamental Darwinian principles and discuss how cancer can be seen through the lens of ecology, evolution, and game theory. We begin with a simple model of cancer growth and add on components of cancer cell competition and drug resistance. To aid in exploration of eco-evolutionary modeling with this approach, we also present a user-friendly software tool. By the end of this paper, we hope that readers will be able to construct basic G function models and grasp the usefulness of the framework to understand the games cancer plays in a biologically mechanistic fashion.

A statistical approach to the study of vitamin C and crude fiber in some horticultural plants to introduce the mediterranean diet

In this didactic paper, using a statistical approach, we introduce the Mediterranean diet, recognized culturally as the patrimony of UNESCO, that promotes a consumption of agrifood, containing vitamin C and crude fibre, that have beneficial effects on the health. This contribution is based on previous papers, where a set of 26 species of horticultural plants, used in Mediterranean diet, was examined from the statistical point of view, obtaining easily accessible and useful results. In particular the recorded content of vitamin C and crude fibre of the considered plants, based on literature data, have been analyzed as two sample variables. Graphic representations and statistical studies are given for these 2 variables. From the average values found of crude fibre and vitamin C contents, ingested by the human organism through the consumption of the considered fruits and vegetables, it can be seen that it is necessary to follow a diet rich in vitamin C and crude fibre to prevent disease, in accordance with medical standards and directives coming from several national and international nutrition organizations, and thus to promote the Mediterranean diet, that represents the initial steps to longevity and good health.

A non-equilibrium thermodynamic approach to study the behaviour of magnetizable media

In this didactic paper we formulate a linear theory for magnetizable media in the framework of classical irreversible thermodynamics (CIT) and using its general methods we investigate the behaviour of these media and the possibility of cross effects among mgnetic phenomena, heat conduction, electric conduction and mechanical phenomena. In Galilean approximation all the processes occurring inside these materials are governed by two groups of laws: Maxwell equations and the balance equations. The entropy production is analyzed following the classical thermodynamic procedures and the constitutive equations in the linear anisotropic and isotropic case are derived. The obtained results have applications in several fields of applied sciences, like medicine, biology, physics, chemistry and others.

A didactic introduction to models and devices to mitigate seismic actions

In this didactic paper basic concepts of seismic isolation are discussed. Models and devices of isolating structures to mitigate seismic actions are presented. As an application an easy example is illustrated in the case of a single degree of freedom (SDOF) structure, showing as basic knowledges of mathematics are fundamental to formulate and solve problems in different fields of applied sciences, as seismic engineering. The aim of this paper is to give a simple lecture on techniques used to prevent the effects of an earthquake in a country.

In Reply to Schultheiss

We thank Dr Schultheiss for his interest in our publication,1 his valuable insights, and for highlighting the excellent didactic paper by Dr David F. Herring2 that provided the pioneering foundations for use of statistical approaches, including maximum likelihood and testing the fit in dose response modeling. Our paper aimed to demonstrate in a practical step-by-step manner the full process of building a dose response model starting with data-driven approaches and describing potential pitfalls for practitioners and newbies to the field.

Ilustrar ou induzir?

Trabalhos de Campo (TC) são atividades imprescindíveis à formação intelectual, profissional e técnica dos estudantes de Geociências. Um objetivo didático dos TC é o exercício do raciocínio geológico típico no desenvolvimento de habilidades de observação e interpretação. Pesquisaram-se os papéis didáticos dos TC realizados por alunos do curso técnico em mineração integrado ao ensino médio no Estado do Espírito Santo, comparando-se um TC com papel didático ilustrativo, com outro TC cujo papel é indutivo. Um questionário teve a finalidade de investigar se: (1) os objetivos pretendidos pelos TC são alcançados? (2) os estudantes percebem os papéis didáticos? Os resultados mostraram que a maioria dos participantes compreendeu os objetivos e, tanto nos TC ilustrativos como nos indutivos os participantes consideram predominar o método de ensino centrado no aluno. As respostas sobre lógica predominante no processo indicaram certo equilíbrio entre a lógica do aprendiz e lógica da ciência e do aprendiz.

Indirect methods in nuclear astrophysics

It is well known that measuring cross-sections of thermonuclear reactions at the low energies typical of astrophysical sites is very difficult. This is due to the presence of the Coulomb barrier between the interacting nuclei. For non-explosive scenarios at astrophysical sites, the relevant energies typically span from few tens to few hundreds of keV while the Coulomb barrier is in the order of MeV. The fusion processes then proceed via tunnel effect and their cross-sections are strongly depending on the probability of penetration through the barrier. In a first approximation, this probability is given by the Gamow factor. Owing to the exponential decrease in this factor with energy, the cross-section values of thermonuclear fusion processes in stellar systems often reach values as small as micro- and nanobarn and even lower ones. Neutron-induced reactions, in spite of the absence of Coulomb barrier, are also difficult to measure. Indeed, it is the possible presence of a centrifugal barrier that can hinder the measurement of the values of the cross-sections of these processes. In either cases the cross-sections of astrophysical nuclear processes result in experimental difficulties, due to the low signal-to-noise ratio, that have been a challenge for scientists since the setting of this scientific field: Nuclear Astrophysics. In the last two to three decades, experimental improvements, including the construction of underground laboratories, allowed for the first time the measurement of cross-sections of astrophysical nuclear processes in the relevant energy region for astrophysics. Also, indirect methods were developed. As a general and common feature, using these methods it is possible to relate the features --typically the cross-section-- of a process that is experimentally simpler to measure, although not directly linked to astrophysics, to those of another process that is of interest for this latter field. This didactic paper will briefly describe some of these indirect methods with a special emphasis on Trojan Horse and on its application also to reactions that involve the use of radioactive ion beams and to neutron-induced reactions.

A practical guide for the identification of major sulcogyral structures of the human cortex.

The precise sulcogyral localization of cortical lesions is mandatory to improve communication between practitioners and to predict and prevent post-operative deficits. This process, which assumes a good knowledge of the cortex anatomy and a systematic analysis of images, is, nevertheless, sometimes neglected in the neurological and neurosurgical training. This didactic paper proposes a brief overview of the sulcogyral anatomy, using conventional MR-slices, and also reconstructions of the cortical surface after a more or less extended inflation process. This method simplifies the cortical anatomy by removing part of the cortical complexity induced by the folding process, and makes it more understandable. We then reviewed several methods for localizing cortical structures, and proposed a three-step identification: after localizing the lateral, medial or ventro-basal aspect of the hemisphere (step 1), the main interlobar sulci were located to limit the lobes (step 2). Finally, intralobar sulci and gyri were identified (step 3) thanks to the same set of rules. This paper does not propose any new identification method but should be regarded as a set of practical guidelines, useful in daily clinical practice, for detecting the main sulci and gyri of the human cortex.

Removing Quasi-Periodic Noise in Strain Maps by Filtering in the Fourier Domain

Quasi-periodic noise due to various reasons often corrupts strain maps obtained with full-field measuring systems. The aim of this didactic paper is to show how to remove this noise by changing some Fourier coefficients involved in the two-dimensional (2D) Fourier transform of these strain maps. The basics of the 2D Fourier transform of images, which is a common tool in image processing but that is only scarcely employed in the experimental mechanics community, are first briefly recalled. Several procedures employed for removing undesirable frequencies in strain maps are then discussed. Three different examples illustrate the benefit of this approach.

Pourquoi la flore intestinale a-t-elle vocation à devenir médicament ?

The gut microbiota (or gut flora) is a set of bacteria living in symbiosis with the host. Strictly associated with the intestinal tract and interacting with it, the gut microbiota is not a tissue nor an organ, but a supra-organism. A disruption of dialogue between bacteria and human cells is a risk factor or a possible cause of various diseases. The restoration of this dialogue, thanks to the transfer of the gut microbiota of a healthy individual to a patient whose balance of gut flora has been broken, is a new therapeutic approach. If its exact effect still eludes scientific understanding, its clinical benefit is well established for an indication, and is recently being tested for many others. The proven contribution of gut microbiota in the human physiological balance calls for intensifying research throughout the world about the state of knowledge and technologies, as well as on the legal and ethical dimension of fecal microbiota transfer. This didactic paper updates the questions in relation with this therapeutic act.

In vitro high throughput screening, what next? Lessons from the screening for aurora kinase inhibitors.

Based on in vitro assays, we performed a High Throughput Screening (HTS) to identify kinase inhibitors among 10,000 small chemical compounds. In this didactic paper, we describe step-by-step the approach to validate the hits as well as the major pitfalls encountered in the development of active molecules. We propose a decision tree that could be adapted to most in vitro HTS.

BINDING WOMEN TOGETHER IN FRIENDSHIP AND UNITY?

This article examines the ethos and rationale of The Woman Worker, launched in Britain in September 1907 as the official organ of the all-female trade union, the National Federation of Women Workers (the Federation). As a monthly journal, it was edited and managed by Mary Macarthur, President of the Federation, moving to weekly production in June 1908 with the assistance of Robert Blatchford, founder of the successful socialist newspaper, The Clarion. Under Macarthur, the paper emphasised both the importance of union organisation for women workers and the need for parliamentary legislation to protect them from low pay, victimisation and exploitation in the workplace. It is argued here that although this paper sought to fill a gap in the market, producing a paper that appealed beyond those already converted to the cause of women's organisation was a difficult challenge for Macarthur. Her attempts to provide a readable but didactic paper on a limited budget, relying on Labour colleagues for copy, resulted in a paper that did not always have a clear target readership; it was a union journal seeking broad appeal amongst working-class women but it also reflected the interests of committed labour activists. This arguably resulted in a paper that struggled to achieve its initial aim of binding women workers together.

Phenomenologically-informed inquiry in physical rehabilitation: how to do documentation and interpretation of qualitative data

In this didactic paper, I offer an example of how we can use a phenomenologically-informed sociological approach to analyse ethnographic and interview data from a clinical encounter. I show that the value of this approach is not that we will reach a more accurate interpretation of qualitative data, but that it opens up multiple ways of seeing and interpreting thus challenging us to re-think our scientific and lay assumptions. By explicating the interpretation process, I hope to increase awareness of how theoretical and practice assumptions may hinder deep, nuanced, and new understandings of clinical encounters. In doing so, physiotherapists and other health professionals can see the value of seeing clinical encounters beyond clinical models and ask questions of how they understand their work environments and clients.

Distinguishing Between-Person and Within-Person Relationships in Longitudinal Health Research: Arthritis and Quality of Life

Many health measures (e.g., blood pressure, quality of life) have meaningful fluctuation over time around a relatively stable mean level for each person. This didactic paper describes two closely related statistical models for examining between-person and within-person relationships between two or more sets of measures collected over time: the latent intercept model with correlated residuals (LI) in structural equation modeling framework and the multivariate multilevel model (MVML) in multilevel modeling framework. We illustrated that the basic LI model and the MVML model are equivalent. We presented an illustrative example using a national arthritis data resource to examine between-person and within-person relationships of symptom status, functional health, and quality of life in arthritis patients. Additional design and modeling issues for the treatment of missing data are considered. We discuss contexts in which one of the two models may be preferred. Mplus and SAS syntax are available.

Controle de estímulos e relações de equivalência

Opresente artigo didático descreve a trajetória da área de controle de estímulos até a proposição do paradigma de equivalência, definindo e encadeando os principais conceitos envolvidos e suas implicações à compreensão crescente de processos comportamentais complexos, tais como o aprendizado do comportamento verbal, da noção de "significado" e dos comportamentos simbólicos, em geral. Apresenta a lógica dos primeiros experimentos de Sidman, indicando o caminho indutivo e cuidadoso do autor até chegar à proposição do paradigma de equivalência e aponta as implicações educacionais do modelo (economia no ensino, procedimentos para ensino de leitura, escrita e comportamento matemático), bem como novos estudos na área que prometem implicações para o contexto clínico.

On the Relation between Power and Reliability of Difference Scores

The potential problems which may arise from the use of difference (a.k.a., gain) scores in the measurement of change are well documented, including (a) difference scores are often negatively correlated with initial ability, and (b) they often tend to be unreliable. Conversely, they make excellent dependent variables in a true experiment since they tend to reduce variability due to individual differences among persons. This brief didactic paper presents a conclusion similar to Nicewander and Price, using a perhaps more straightforward argument based on difference scores. We argue that the same reason difference scores provide powerful significance tests, namely, reduction of "true score" variance, is also the reason they tend to be unreliable. Further, we make the point that reducing true score variance will increase the power of a significance test (since it will reduce the denominator or "error term" of the observed statistic) but will decrease reliability (since it is the numerator and a component of the denominator of the reliability coefficient).

ON THE RELATION BETWEEN POWER AND RELIABILITY OF DIFFERENCE SCORES

The potential problems which may arise from the use of difference (a.k.a., gain) scores in the measurement of change are well documented, including (a) difference scores are often negatively correlated with initial ability, and (b) they often tend to be unreliable. Conversely, they make excellent dependent variables in a true experiment since they tend to reduce variability due to individual differences among persons. This brief didactic paper presents a conclusion similar to Nicewander and Price, using a perhaps more straightforward argument based on difference scores. We argue that the same reason difference scores provide powerful significance tests, namely, reduction of “true score” variance, is also the reason they tend to be unreliable. Further, we make the point that reducing true score variance will increase the power of a significance test (since it will reduce the denominator or “error term” of the observed statistic) but will decrease reliability (since it is the numerator and a component of the denominator of the reliability coefficient).

Effective poster design.

A poster is an abstract. The mistake most frequently made is to put too much information on your poster. Your poster should be an eye-catcher, containing a brief message, understood at a glance. It is claimed that you have about three seconds to catch the audience’s attention. To achieve this ’’three second hit’’ there are some aspects that you can take into account when you set out to design a poster. This brief didactic paper addresses the issues that help you create an attractive and effective poster (BMA & BLATHE, 1973; Newble et al., 1994).

An introduction to the theory of local mode vibrations

A description is given of highly excited rotational and/or vibrational states of molecules in terms of localized vibrations or local modes. It is a didactic paper, making an attempt to unify the ideas and notations of the key publications on the subject in a manner that treats the vibrational and rotational motions equally and that demonstrates the importance of molecular symmetry. Emphasis is put on explaining the intimate relationship between local mode vibrations and the formation of both vibrational and rovibrational energy level clusters. In rovibrational cluster states, a molecule can sustain localized vibrations for very many vibrational periods, even with low vibrational excitation. Local mode behaviour is induced by both vibrational and rotational excitation. An important application of local mode theory is the derivation of relations between the effective rotation-vibration parameters for highly excited vibrational states of a molecule. It is shown here, using the H2 80Se molecule as example, that such relations are valid only for certain forms of the effective rotation-vibration Hamiltonian. Thus caution is required when the results of fittings to spectral data are compared with local mode theory.

Review of fluorescence anisotropy decay analysis by frequency-domain fluorescence spectroscopy

This didactic paper summarizes the mathematical expressions needed for analysis of fluorescence anisotropy decays from polarized frequency-domain fluorescence data. The observed values are the phase angle difference between the polarized components of the emission and the modulated anisotropy, which is the ratio of the polarized and amplitude-modulated components of the emission. This procedure requires a separate measurement of the intensity decay of the total emission. The expressions are suitable for any number of exponential components in both the intensity decay and the anisotropy decay. The formalism is generalized for global analysis of anisotropy decays measured at different excitation wavelengths and for different intensity decay times as the result of quenching. Additionally, we describe the expressions required for associated anisotropy decays, that is, anisotropy decays where each correlation time is associated with a decay time present in the anisotropy decay. And finally, we present expressions appropriate for distributions of correlation times. This article should serve as a reference for researchers using frequency-domain fluorometry.