Analogies in science and science teaching

Analogies are often used in science, but students may not appreciate their significance, and so the analogies can be misunderstood or discounted. For this reason, educationalists often express concern about the use of analogies in teaching. Given the important place of analogies in the discourse of science, it is necessary that students are explicitly shown how they work, perhaps based on the structure-mapping theory we outline here. When using an analogy, the teacher should very clearly specify both its components and its limitations. Great care is required in developing an analogy to ensure that it is understood as intended and that misconceptions are minimized. This approach models the behavior of a scientist, which helps to develop student understanding of the practice of science.     

Two-Dimensional Analogies to Frequency-Selective Surfaces (FSS) on the Graphene Sheet

In this paper, we propose that two-dimensional analogies to frequency-selective surfaces (FSS) can be achieved on graphene surfaces based on transformation optics. The analogies to representative FSS structures, including the anti-reflecting coating (ARC) and the high-reflecting coating (Bragg reflector), have been investigated through both analytical effective-index method (EIM)/transfer-matrix method (TMM) and numerical simulations. Both analytical and numerical solutions have shown that the propagation of plasmons on graphene surface with periodic chemical potentials can be an analogy to the interaction of incident light with traditional FSS multilayer dielectric media in which the transmission or reflection can be obtained by EIM/TMM. Combined with the tunability of graphene, the transmission or reflection of plasmons can be tuned by adjusting the bias voltage. The proposed structures and theoretical methods may provide new visions for achieving two-dimensional analogies to traditional structures on graphene.

     

Arguing by analogy in the fetal tissue debate

In the debate over fetal tissue use, an analogy is often drawn between removing organs from the body of a person who has been murdered to use for transplantation, and collecting tissue from an aborted fetus to use for the same purpose. The murder victim analogy is taken by its proponents to show that even if abortion is the moral equivalent of murder, there is still no good reason to refrain from using the fetal tissue, since as a society we do not see any problem about using organs from murder victims. However, I argue that the analogy between murder victims and aborted fetuses does not hold — the two situations are not the same in all morally relevant respects. Thus the murder victim analogy does not provide an argument in favour of fetal tissue transplant. In conclusion, I point to some of the potential pitfalls of using analogies in ethical argument.     

A dark business,full of shadows: Analogy and theology in William Harvey

In a short work called De conceptione appended to the end of his Exercitationes de generatione animalium (1651), William Harvey developed a rather strange analogy. To explain how such marvelous productions as living beings were generated from the rather inauspicious ingredients of animal reproduction, Harvey argued that conception in the womb was like conception in the brain. It was mostly rejected at the time; it now seems a ludicrous theory based upon homonymy. However, this analogy offers insight into the structure and function of analogies in early modern natural philosophy. In this essay I hope to not only describe the complex nature of Harvey’s analogy, but also offer a novel interpretation of his use of analogical reasoning, substantially revising the account offered by Guido Giglioni (1993). I discuss two points of conceptual change and negotiation in connection with Harvey’s analogy, understanding it as both a confrontation between the border of the natural and the supernatural, as well as a moment in the history of psychology. My interpretation touches upon a number of important aspects, including why the analogy was rejected, how Harvey systematically deployed analogies according to his notions of natural philosophical method, how the analogy fits into contemporary discussions of analogies in science, and finally, how the analogy must be seen in the context of changing Renaissance notions of the science of the soul, ultimately confronting the problem of how to understand final causality in Aristotelian science. In connection with the last, I conclude the essay by turning to how Harvey embeds the analogy within a natural theological cosmology.     

The GTM Analogy: The “Organismic” Metaphor Revisited?

Metaphors and analogies have long been used as heuristic and explanatory devices in the sciences. This focal review comments on the article "The Transmission of Genes and Culture: A Questionable Analogy" by Drs. Cladiere and Andre, and discusses the usefulness of the GTM analogy for understanding the transmission of culture.     

The fluid mechanics of nutrition: Herman Boerhaave's synthesis of seventeenth-century circulation physiology

This paper investigates the theory of nutrition of Herman Boerhaave, the famous professor of medicine and chemistry at the university of Leyden. Boerhaave's work, which systematized and synthesized the knowledge of the time, represents a shift from a humoral to a hydraulic model of the body in medicine and culture around 1700. This epistemological reconfiguration of early modern physiological thinking is exemplified with respect to the changing meanings of milk. While over centuries the analogy between blood and milk played an essential role in understanding the hidden workings of the nutritional faculties, following the discovery of the blood circulation the blood-milk analogy was transformed into a chyle-milk analogy. Yet Boerhaave's interpretations show that the use of new knowledge tools did not simply displace the old ways of reasoning. Instead, analogies continued to serve as epistemic instruments. Old theories and new insights overlapped, and contemporary knowledge assimilated past ideas.     

Is whole-culture synchronization biology's 'perpetual-motion machine'?

Whole-culture or batch synchronization cannot, in theory, produce a synchronized culture because it violates a fundamental law that proposes that no batch treatment can alter the cell-age order of a culture. In analogy with the history of perpetual-motion machines, it is suggested that the study of these whole-culture 'synchronization' methods might lead to an understanding of general biological principles even though these methods cannot be used to study the normal cell cycle.     

A machine-learning approach to calibrate generic Raman models for real-time monitoring of cell culture processes

The manufacture of biotherapeutic proteins consists of complex upstream unit operations requiring multiple raw materials, analytical techniques, and control strategies to produce safe and consistent products for patients. Raman spectroscopy is a ubiquitous multipurpose analytical technique in biopharmaceutical manufacturing for real-time predictions of critical parameters in cell culture processes. The accuracy of Raman spectroscopy relies on chemometric models that need to be carefully calibrated. The existing calibration procedure is nontrivial to implement as it necessitates executing multiple carefully designed experiments for generating relevant calibration sets. Further, existing procedure yields calibration models that are reliable only in operating conditions they were calibrated in. This creates a unique challenge in clinical manufacturing where products have limited production history. In this paper, a novel machine-learning procedure based on just-in-time learning (JITL) is proposed to calibrate Raman models. Unlike traditional techniques, JITL-based generic Raman models can be reliably used for different modalities, cell lines, culture media, and operating conditions. The accuracy of JITL-based generic models is demonstrated on several validation studies involving real-time predictions of critical cell culture performance parameters, such as glucose, glutamate, glutamine, ammonium, lactate, sodium, calcium, viability, and viable cell density. The proposed JITL framework introduces a paradigm shift in the way industrial Raman models are calibrated, which to the best of authors’ knowledge have not been done before.     

Analogies to demonstrate the effect of roughness on surface wettability

This article presents an analogy to illustrate the effect of surface roughness on surface wettability. I used a water-filled balloon to represent water droplet, a toothpick to represent surface roughness and Styrofoam as the surface. The analogies presented in this article will help visualize how roughness affects the wettability of the surface and therefore can be used to introduce surface wettability to high school students.     

Elicitation with methyl-jasmonate stimulates peruvoside production in cell suspension cultures of <Emphasis Type="Italic">Thevetia peruviana</Emphasis>

Thevetia peruviana is a small tree that produces several compounds with pharmaceutical application, among which peruvoside could be highlighted. However, these compounds are produced in low concentration in the plant, making it important to develop strategies such as plant cell culture and elicitation to obtain higher quantities of the desired product. In this work, cell suspension cultures of T. peruviana were established in four different culture media: Murashige–Skoog (MS), half Murashige–Skoog (half MS), Schenk–Hildebrandt (SH), and Gamborg (B5) to study their effect on cell growth. Cell growth kinetics were studied in SH medium, and the extracellular peruvoside production during the culture time was determined. The best culture medium for the establishment of cell suspension cultures was MS with a growth index of 3.17 ± 0.2 g g⁻¹ inoculum. The cell growth kinetics showed the four characteristic growth phases of a cell culture (lag, exponential, stationary, and death), and during none of these phases was it possible to observe peruvoside production. The elicitor effect of methyl-jasmonate (MeJ) was studied in cell suspension cultures established in SH medium. The effect of MeJ concentration and the time in which it should be applied were determined. The best results were obtained at a concentration of 100 mg l⁻¹ of MeJ applied at the beginning of the culture, which induced a peruvoside production of 8.93 mg l⁻¹ medium. The current results are the first report of an in vitro peruvoside production system.     

RECLAIMING THE PATIENT'S VOICE AND SPIRIT IN DYING: AN INSIGHT FROM ISRAEL

In the latter half of the 20th century, Western medicine moved death from the home to the hospital. As a result, the process of dying seems to have lost its spiritual dimension, and become a matter of prolonging material life by means of medical technology. The novel quandaries that arose led in turn to medico‐legal regulation. This paper describes the recent regulation of dying in Israel under its Dying Patient Law, 2005. The Law recognizes advance directives in principle, but limits their effect and form through complex medico‐legal artifices. It reflects a culture that places high value on both scientific medicine and the sanctity of life as such, and illustrates a medical culture that pitches battle against death. At the same time, the Law constructs the will of the individual in a medico‐legal language that is alien to the lay person. The paper suggests an alternative approach to advance care planning that is patient‐centred and addresses the psycho‐social needs of the individual in terms of her relational autonomy. From this perspective, advance care planning becomes an opportunity to extract the patient from the medical context and allow her to speak about her approaching death with close ones in her own terms of reference. To this end, there is a need for facilitation of an intimate encounter where patients can speak about their concerns with their loved ones. The paper also presents a methodological approach of attentive listening, which can be applied across diverse cultures and circumstances.     

High-tech brains: a history of technology-based analogies and models of nerve and brain function

This article reviews some of the technological devices and ideas which have been used over the years to answer the question, how does the brain work? It describes some of the early technology-based analogies and models of nerve fibers, and then discusses other analogies and models of the brain based on mechanical and electrical technologies. There are also short sections on cybernetics, telephone exchanges, and computers. Although all of these ideas are flawed to some extent, this article offers a brief argument on the usefulness of analogy and abstraction in brain science.     

Cell Growth and Division: II. Experimental Studies of Cell Volume Distributions in Mammalian Suspension Cultures

Experimental proof is given that the volume distribution spectrum of mammalian cells in suspension culture can be determined accurately with a Coulter spectrometer. Stable spectra corresponding to the predictions of a mathematical model are observed under favorable conditions of growth. Cell volume spectrometry appears to be a useful method for diagnosing the state of the culture with respect to past uniformity of growth rate and present population age distribution. In addition, it offers a method for quantitative study of the laws governing cell growth and division.     

Modelling the acidifying activity profile of Lactobacillus bulgaricus cultures

A model that fully describes the typical pH(t) profile representing the lactic acid production kinetics of Lactobacillus bulgaricus cultures is reported. The model, a four-parameter function [pH = (A–D)/(1 + (t/C)^B) + D], is able to fit any change on the experimental pH-time curves, due to variations on the inoculum cell concentration of the culture. The four fitting parameters(A, B, C and D) of this model are closely related to the lactic acid fermentation and they have a physical meaning. Parameters A and D represent the initial and final pH of the culture, respectively. Parameter B is related to the slope of the linear decreasing region from the pH-time curve and C represents the time at which half of the total decrement of pH is achieved. The proposed model can be used not only for evaluating and comparing the acidifying capacity of homolactic cultures but also for predictions of final fermentation times.     

WELLBEING,SCHIZOPHRENIA AND EXPERIENCE MACHINES

In the USA and England and Wales, involuntary treatment for mental illness is subject to the constraint that it must be necessary for the health or safety of the patient, if he poses no danger to others. I will argue against this necessary condition of administering treatment and propose that the category of individuals eligible for involuntary treatment should be extended. I begin by focusing on the common disorder of schizophrenia and proceed to demonstrate that it can be a considerable harm to a person's life without causing the person to be a danger to himself. I illuminate this claim by constructing a thought experiment concerning a person who slips on a banana peel and falls into a malfunctioning version of Robert Nozick's experience machine. I propose that the reasons why we should remove the person from the machine are the same reasons why we should administer involuntary treatment to individuals with schizophrenia. I rebut three objections to the analogy and conclude that if we believe that we have a duty to provide treatment for reasons relating to a person's wellbeing, it follows that we should reject the health or safety requirement and instead broaden the category of individuals who are eligible for involuntary treatment.     

PROSPECTS FOR “GENETIC THERAPY” - CAN A PERSON BENEFIT FROM BEING ALTERED?

Mapping the human genome is an immense project with numerous objectives. Indeed, it is likely that some of its most important ramifications and applications remain as yet unglimpsed. All we can presently attempt is to focus on some of the more obvious possibilities and prepare for the problems already looming on our horizon. One such possibility is that of Prenatal Genetic Intervention (PGI), which might be said to be a therapeutic intervention on behalf of the embryonic child. In this paper, I argue that "genetic therapy" is likely to be a misnomer, and that if PGI becomes possible, we should generally resist its inclusion under the special moral duty of providing health care. "Therapy" necessarily means helping a person, while PGI -- though effecting improvements from an impersonal perspective -- will frequently not consist in directly helping any person. This is due not to the embryo not being a person, but rather to the basic philosophical problem of personal identity persisting through significant alterations -- especially the alteration of genotype. The decisive moral question then hinges on the definition of "significant" alteration. I shall examine the feasibility of drawing analogies from criteria for personal identity proposed in discussions of how persons maintain their identity across time and through physical and psychological change. Certain metaphysical aspects of human identity and individuality will be also touched upon, partly in terms derived from classical Judaism. In conclusion I argue that, regarding embryos in particular, persistence of genotype must generally be deemed a necessary condition for maintaining personal identity. Therefore, many proposals for PGI should be excluded from the notion of therapeutic intervention and thus denied the special moral status of requests for therapy.     

Using Laser Tweezers For Manipulating Isolated Neurons In Vitro

In this paper and video, we describe the protocols used in our laboratory to study the targeting preferences of regenerating cell processes of adult retinal neurons in vitro. Procedures for preparing retinal cell cultures start with the dissection, digestion and trituration of the retina, and end with the plating of isolated retinal cells on dishes made especially for use with laser tweezers. These dishes are divided into a cell adhesive half and a cell repellant half. The cell adhesive side is coated with a layer of Sal-1 antibodies, which provide a substrate upon which our cells grow. Other adhesive substrates could be used for other cell types. The cell repellant side is coated with a thin layer of poly-HEMA. The cells plated on the poly-HEMA side of the dish are trapped with the laser tweezers, transported and then placed adjacent to a cell on the Sal-1 side to create a pair. Formation of cell groups of any size should be possible with this technique. "Laser-tweezers-controlled micromanipulation" means that the investigator can choose which cells to move, and the desired distance between the cells can be standardized. Because the laser beam goes through transparent surfaces of the culture dish, cell selection and placement are done in an enclosed, sterile environment. Cells can be monitored by video time-lapse and used with any cell biological technique required. This technique may help investigations of cell-cell interactions.Open in a separate windowClick here to view.^{(66M, flv)}     

Seeing tissue as a 'phase of matter': exploring statistical mechanics for the cell

The field of tissue engineering aims to produce living, biological constructs which possess the appropriate spatial ordering of cells and their extra cellular matrix products. The complexity of a single cell and its interactions in a large collective have made development of useful models to assist in tissue culture difficult, and consequentially most tissue culture endeavors are limited to trial and error approaches. Some cell types display a natural tendency to spontaneously self-assemble into large domains of parallel-oriented cells. In this work, we show that these cell culture systems can be studied in the context of continuous disorder-order phase transformations. We suggest that collective ordering of the cells is controlled by the amount of noise in the walk of the individual cells (directional persistence) because undifferentiated mesenchymal stem cells display a seven-times higher directional persistence than mature fibroblasts and have a 24-times larger final-oriented domain size, an observation that corresponds with collective ordering in self-propelled particle systems. The study of cell culture systems using analogies derived from statistical mechanics yields simple, practical models offering insight into how a long-range order can be obtained in tissue-engineered constructs, providing a new paradigm for managing operations with large collectives of living cells.     

Evolutionary responses to global change: lessons from invasive species

Biologists have recently devoted increasing attention to the role of rapid evolution in species' responses to environmental change. However, it is still unclear what evolutionary responses should be expected, at what rates, and whether evolution will save populations at risk of extinction. The potential of biological invasions to provide useful insights has barely been realised, despite the close analogies to species responding to global change, particularly climate change; in both cases, populations encounter novel climatic and biotic selection pressures, with expected evolutionary responses occurring over similar timescales. However, the analogy is not perfect, and invasive species are perhaps best used as an upper bound on expected change. In this article, we review what invasive species can and cannot teach us about likely evolutionary responses to global change and the constraints on those responses. We also discuss the limitations of invasive species as a model and outline directions for future research.