Recently, it has been argued that the phenomenon of direct transfer of intermediate metabolites between adjacent enzymes, also known as metabolic channelling, would not decrease the concentration of those intermediates in the bulk solution. However, this conclusion has been drawn by extrapolation from the results of simulations with a rather restricted set of parameters. We show that, for a number of kinetic cases, the existence of metabolic channelling can decrease the size of the soluble pool of intermediates. When the (...) class='Hi'>enzyme(s) downstream of the channel have a catalytic capacity that is large relative to the enzymes upstream of the channel, the decrease of concentration can be substantial (3 orders of magnitude). (shrink)

The Enzymatic control reactions model was presented within the scope of fractional calculus. In order to accommodate the usual initial conditions, the fractional derivative used is in Caputo sense. The methodologies of the three analytical methods were used to derive approximate solution of the fractional nonlinear system of differential equations. Two methods use integral operator and the other one uses just an integral. Numerical results obtained exhibit biological behavior of real world problem.

The Enzymatic control reactions model was presented within the scope of fractional calculus. In order to accommodate the usual initial conditions, the fractional derivative used is in Caputo sense. The methodologies of the three analytical methods were used to derive approximate solution of the fractional nonlinear system of differential equations. Two methods use integral operator and the other one uses just an integral. Numerical results obtained exhibit biological behavior of real world problem.

Kinetic models using enzyme kinetics are developed for the three ways that Louie proved that Rosen’s minimal (M-R)-System can be closed to efficient cause; i.e., how the “replication” component can itself be entailed from within the system. The kinetic models are developed using the techniques of network thermodynamics. As a demonstration, each model is simulated using a SPICE circuit simulator using arbitrarily chosen rate constants. The models are built from SPICE sub-circuits representing the key terms in the chemical (...) rate equations. The models include the addition of an ad hoc semi-permeable membrane so the system can achieve steady state fluxes and also to illustrate the need for all the efficient cause agents to be continually replaced. Comments are made about exactly what is being simulated. (shrink)

We present a method to determine the reaction type and kinetic constants for enzyme inhibitors that decreases the number of experimental assays by at least a factor of five. It is based on a new theoretical formalism in terms of concentrations that dismisses the requirement of estimating initial velocities. Expressions for the time evolution of the concentrations of all the reactants are also given.

Throughout its matrix of atoms, myoglobin has a network of cavities that are inhabited for short lengths of time by ligands released by photolysis from the myoglobin heme. The purpose or effect of this cavity network is not clear. A recently published kinetic scheme that fits data from many native and mutant myoglobin oxygen photolysis experiments can be modified easily into a kinetic scheme that includes kinetic proofreading. Proofreading would provide protection against contaminants and, specifically, might help protect the cell (...) from carbon monoxide poisoning. Here we present a two‐part model: (1) myoglobin represented by a kinetic description, which includes proofreading reactions associated with the cavities, and (2) a reaction–diffusion description of a myocyte model in which the part 1 myoglobin acts as a mobile buffer in simultaneous carbon monoxide and oxygen gradients. The non‐equilibrium nature of part 2 should promote the proofreading function of part 1. A simulation using the model demonstrates that the cavity system can in principle proofread, reducing mitochondrial enzyme contamination. BioEssays 26:422–433, 2004. © 2004 Wiley Periodicals, Inc. (shrink)

The mechanistic significance of a kinetic isotope effect on a cytochrome P‐450catalyzed reaction depends, fundamentally, on the nature of the interaction of the substrate with the active site of the enzyme as well as on the nature of the chemistry of the reaction catalyzed. Consequently, kinetic isotope effects can be used to extract information on the topology of the enzyme and the mechanism of substrate oxidation. Kinetic isotope effect studies are sometimes accompanied by ‘metabolic switching’ or a change (...) in metabolic pathway, catalyzed either by the same enzyme or by a different enzyme. For the specific case where ‘metabolic switching’ gives rise to a change in regional specificity for the cytochrome P‐450 catalyzed metabolism of a compound, this change can be explained in terms of the topological constraints on substrate binding imposed by the active site of the enzyme. (shrink)

The fructose 6-phosphate (Fru-6P) saturation curve for phosphofructokinase (PFK) from E. coli is sigmoidal in the presence of saturating MgATP levels, while the corresponding curve for B. stearothermophilus PFK is essentially hyperbolic. Sigmoidality can be due to apparent cooperativity arising from the kinetic mechanism of an enzyme. We have determined the kinetic mechanism of B. stearothermophilus PFK (BsPFK). BsPFK was found to obey a non rapid-equilibrium random mechanism similar to the one E. coli PFK (EcPFK) follows. Substrate inhibition by (...) MgATP was observed. We propose that substrates bind to BsPFK through two alternative pathways, one of which is slower. The substrate inhibition arises in part from reaction flux through the slower pathway. Although EcPFK and BsPFK obey similar kinetic mechanisms, they are inhibited differently by MgATP: EcPFK is profoundly inhibited, BsPFK only weakly. The structural basis for this difference could be closure of the active site via a conformational transition that occurs in EcPFK, but not BsPFK. To investigate the importance of this transition for MgATP inhibition of EcPFK, we have constructed a chimeric enzyme (ChiPFK) that contains the "rigid" ATP-binding domain of BsPFK grafted onto the remainder of the EcPFK subunit. Our results indicate that ChiPFK is locked in an "open" structure resembling the activated form of EcPFK. It is insensitive to heterotropic regulation. Nevertheless, ChiPFK exhibits residual cooperativity. Possible explanations for the cooperativity are discussed. The 6F loop is proposed to be important in PFK allosteric behavior. Residues along the loop are largely conserved between BsPFK and EcPFK, except for 161, which is a glutamate in BsPFK, and a glutamine in EcPFK. Using site-directed mutagenesis, Glu 161 of BsPFK has been changed to glutamine and alanine. Similarly, Gin 161 of EcPFK has been changed to glutamate, arginine and alanine. Of the five mutants, one, QA161, was particularly interesting. Though activated normally by GDP, it was completely insensitive to PEP inhibition. This indicates that the hydrogen-bonding ability of residue 161 is critical for PEP inhibition of EcPFK, and that GDP activation and PEP inhibition follow different structural pathways. (shrink)

We assume the existence of a specific G1 protein which is an initiator of DNA replication. This initiator is supposed to be synthesized according to Michaelis-Menten kinetics. In order to start DNA replication, it is assumed that this G1 specific protein must be produced in a required amount. Intra-cellular growth inhibitors and extra-cellular growth factors control the production of the initiator. This model allows to calculate the average G1 phase time as a function of the various chemical concentrations of (...) nutrients, enzymes, growth inhibitors and growth factors. This model is compared to cell kinetics experiments on a leukemic cell line responding to Interleukin 3 deprivation. The curves giving the experimental average G1 phase times with respect to Interleukin-3 concentrations are fitted by the mathematical model with a quite good agreement. (shrink)

RubisCO is Earth's main enzyme responsible for CO2 fixation via carboxylation of ribulose-1,5-bisphosphate into organic matter. Besides the carboxylation reaction, RubisCO also catalyzes the oxygenation of RuBP by O2, which is probably as old as its carboxylation properties. Based on molecular phylogeny, the occurrence of the reactive oxygen species -removing system and kinetic properties of different RubisCO forms, we postulated that RubisCO oxygenase activity appeared in local microoxic areas, yet before the appearance of oxygenic photosynthesis. Here, in reviewing the (...) literature, we present a novel hypothesis: the RubisCO early oxygenase activity hypothesis. This hypothesis may be compared with the exaptation hypothesis, according to which latent RubisCO oxygenase properties emerged later during the oxygenation of the Earth's atmosphere. The reconstruction of ancestral RubisCO forms using ancestral sequence reconstruction techniques, as a promising way for testing of RubisCO early oxygenase activity hypothesis, is presented. RubisCO catalyzes carboxylation and oxygenation of ribulose-1,5-bisphosphate. Carboxylating properties of RubisCO are an ancient way for CO2 fixation into organic matter. However, an evolutionary importance of oxygenase activity of RubisCO remains enigmatic. Here, we formulated RubisCO early oxygenase activity hypothesis. According to this hypothesis, RubisCO oxygenase activity appeared yet before the appearance of oxygenic photosynthesis. (shrink)

Methods and equations for analysing the kinetics of enzyme-catalysed reactions were developed at the beginning of the 20th century in two centres in particular; in Paris, by Victor Henri, and, in Berlin, by Leonor Michaelis and Maud Menten. Henri made a detailed analysis of the work in this area that had preceded him, and arrived at a correct equation for the initial rate of reaction. However, his approach was open to the important objection that he took no account (...) of the hydrogen-ion concentration (a subject largely undeveloped in his time). In addition, although he wrote down an expression for the initial rate of reaction and described the hyperbolic form of its dependence on the substrate concentration, he did not appreciate the great advantages that would come from analysis in terms of initial rates rather than time courses. Michaelis and Menten not only placed Henri's analysis on a firm experimental foundation, but also defined the experimental protocol that remains standard today. Here, we review this development, and discuss other scientific contributions of these individuals. The three parts have different authors, as indicated, and do not necessarily agree on all details, in particular about the relative importance of the contributions of Michaelis and Menten on the one hand and of Henri on the other. Rather than force the review into an unrealistic consensus, we consider it appropriate to leave the disagreements visible. (shrink)

Many enzymes are inhibited by their own substrates, leading to velocity curves that rise to a maximum and then descend as the substrate concentration increases. Substrate inhibition is often regarded as a biochemical oddity and experimental annoyance. We show, using several case studies, that substrate inhibition often has important biological functions. In each case we discuss, the biological significance is different. Substrate inhibition of tyrosine hydroxylase results in a steady synthesis of dopamine despite large fluctuations in tyrosine due to meals. (...) Substrate inhibition of acetylcholinesterase enhances the neural signal and allows rapid signal termination. Substrate inhibition of phosphofructokinase ensures that resources are not devoted to manufacturing ATP when it is plentiful. In folate metabolism, substrate inhibition maintains reactions rates in the face of substantial folate deprivation. Substrate inhibition of DNA methyltransferase serves to faithfully copy DNA methylation patterns when cells divide while preventing de novo methylation of methyl‐free promoter regions. (shrink)

We consider metabolic networks with reversible enzymatic reactions. The model is written as a system of ordinary differential equations, possibly with inputs and outputs. We prove the global stability of the equilibrium , using techniques of monotone systems and compartmental matrices. We show that the equilibrium does not always exist. Finally, we consider a metabolic system coupled with a genetic network, and we study the dependence of the metabolic equilibrium with respect to concentrations of enzymes. We give some conclusions concerning (...) the dynamical behavior of coupled genetic/metabolic systems. (shrink)

Mitochondrial respiration is the predominant source of ATP. Excessive rates of electron transport cause a higher production of harmful reactive oxygen species (ROS). There are two regulatory mechanisms known. The first, according to Mitchel, is dependent on the mitochondrial membrane potential that drives ATP synthase for ATP production, and the second, the Kadenbach mechanism, is focussed on the binding of ATP to Cytochrome c Oxidase (CytOx) at high ATP/ADP ratios, which results in an allosteric conformational change to CytOx, causing inhibition. (...) In times of stress, ATP‐dependent inhibition is switched off and the activity of CytOx is exclusively determined by the membrane potential, leading to an increase in ROS production. The second mechanism for respiratory control depends on the quantity of electron transfer to the Heme aa3 of CytOx. When ATP is bound to CytOx the enzyme is inhibited, and ROS formation is decreased, although the mitochondrial membrane potential is increased. (shrink)

Heterocyst spacing in blue -green bacteria is widely assumed to be due to a diffusible inhibitor. The inhibitor, a nitrogen-rich compound, probably glutamine, is produced via the N2-fixing enzymes of the heterocyst and in turn serves to suppress the induction of these enzymes and of the differentiation of vegetative cells to heterocysts. This simple morphogenetic mechanism operating in growing cellular filaments ofAnabaena species is investigated on the basis of a continuous and a discrete cellular model, as well as by cell-by-cell (...) simulation of the inhibitor transport. The resulting distances between heterocysts and kinetics of their production are compared with observations, and the values of physical parameters are estimated from the models. (shrink)

In earlier work we have described how computer algebra may be used to derive composite rate laws for complete systems of equations, using the mathematical technique of Gröbner Bases (Bennett, Davenport and Sauro, 1988). Such composite rate laws may then be fitted to experimental data to yield estimates of kinetic parameters.Recently we have been investigating the practical application of this methodology to the estimation of kinetic parameters for the closed two enzyme system of aspartate aminotransferase (AAT) and malate dehydrogenase (...) (MDH) (Fisher 1990a; Fisher 1990b; Bennett and Fisher, 1990). (shrink)

DNA helicases are a class of molecular motors that catalyze processive unwinding of double stranded DNA. In spite of much study, we know relatively little about the mechanisms by which these enzymes carry out the function for which they are named. Most current views are based on inferences from crystal structures. A prominent view is that the canonical ATPase motor exerts a force on the ssDNA resulting in “pulling” the duplex across a “pin” or “wedge” in the enzyme leading (...) to a mechanical separation of the two DNA strands. In such models, DNA base pair separation is tightly coupled to ssDNA translocation of the motors. However, recent studies of the Escherichia coli RecBCD helicase suggest an alternative model in which DNA base pair melting and ssDNA translocation occur separately. In this view, the enzyme‐DNA binding free energy is used to melt multiple DNA base pairs in an ATP‐independent manner, followed by ATP‐dependent translocation of the canonical motors along the newly formed ssDNA tracks. Repetition of these two steps results in processive DNA unwinding. We summarize recent evidence suggesting this mechanism for RecBCD helicase action. (shrink)

This paper investigates the case of enzyme classification to evaluate different ideals for regulating values in science. I show that epistemic and non-epistemic considerations are inevitably and untraceably entangled in enzyme classification, and argue that this has significant implications for the two main kinds of views on values in science, namely, Epistemic Priority Views and Joint Satisfaction Views. More precisely, I argue that the case of enzyme classification poses a problem for the usability and descriptive accuracy of (...) these two views. The paper ends by suggesting that these two views provide different but complementary perspectives, and that both are useful for evaluating values in science. (shrink)

Development of the shapes of living organisms and their parts is a field of science in which there are no generally accepted theoretical principles. What form these principles are likely to take, when they emerge, is a subject in which there is a wide gulf of disagreement between physical scientists and experimental biologists. This book contains both an extensive philosophical commentary on this dichotomy in views and an exposition of the type of theory most favoured by physical scientists. In this (...) theory living form is a manifestation of the dynamics of chemical change and physical transport or other physics of spatial communication. The reaction-diffusion theory, as initiated by Turing in 1952 and since elaborated by Prigogine and by Gierer and Meinhardt among others, is discussed in detail at a level that requires a good knowledge of a first course in calculus, but no more than that. The great growth of molecular biology has tended to overshadow the increase in our understanding of the nature of these kinetic processes. This book seeks to reawaken interest in dynamics in the hope that a better balance between the importance of things and the importance of actions may emerge in the biology of the 21st century. (shrink)

Sport aesthetics is an important but often marginalized field in the philosophy of sport. Kinetic Beauty offers a comprehensive, principled, pluralist introduction to the philosophical aesthetics of sport. The book tackles a wide variety of issues in the philosophical aesthetics of sport, proposing a five-level analysis that coordinates extant scholarship on the same conceptual map, reveals gaps in the literature, and motivates a fresh perspective on stubborn debates and novel topics in the field. This is an excellent resource for professors (...) and students in the philosophy of sport, sport aesthetics, general aesthetics, and the philosophy of art. It is also a fascinating read for those working in kinesiology, sport studies, philosophy, art, and aesthetics. (shrink)

Despite the popularity that the embodied cognition thesis has gained in recent years, explicit memories of events personally experienced are still conceived as disembodied mental representations. It seems that we can consciously remember our personal past through sensory imagery, through concepts, propositions and language, but not through the body. In this article, I defend the idea that the body constitutes a genuine means of representing past personal experiences. For this purpose, I focus on the analysis of bodily movements associated with (...) the retrieval of a personal memory, which have certain features that make them different from procedural memories, pragmatic actions and common gestures, as well as other forms of embodied memories found in recent literature. I refer to these as “kinetic memories” and analyse their representative nature as well as their adaptive functions. Kinetic memories are bodily movements in which some event or action that took place in the past can be seen, because they are an externalisation of the subject’s inner intention of representing a past personal experience. Kinetic memories represent a past experience sometimes by imitation of a past movement, and other times through embodied symbols and metaphors. Furthermore, although sometimes they present direct pragmatic benefits, such as communicative benefits, they seem to enhance the whole reexperience of the past event and memory recall, which I argue is one important adaptive value. (shrink)

We show that in a dilute gas the wave function’s spreading is limited by scattering off other particles. This shows that quantum mechanics can be consistent with the kinetic theory of gases.

The aim of this paper is to compare various methods for the quantification of metabolic pathways dynamics. A Yates-Pardee metabolic pathway with enzyme organization, i.e. with spatial localization of the enzymes in a specific cellular compartment, was studied using: (i) the classical Henri-Michaelis-Menten (HMM) equations, (ii) linearization of the HMM equations in the vicinity of a steady state (linearized formalism), and (iii) Biochemical Systems Theory formalism (BST formalism). It is shown that transient solutions computed via either the linearized formalism (...) or the BST formalism can greatly differ from transient solutions computed with the HMM equations. However, in the studied example, results remain qualitatively the same for the three formalisms. This suggests that the study of the topology of the system may give useful insights into the metabolic pathways dynamics. (shrink)

In this paper I shall offer new definitions for what seem to be the most dominant terms in Epicurus’ theory of pleasures - “kinetic” and “katastematic”. While most of the scholarly literature treats these terms as entirely concerned with states of motion and states of stability, I shall argue that the distinction concerns whether pain is or is not removed by this or that pleasure. As the removal of pain is a necessary condition for the Epicurean goal of ataraxia and (...) aponia, “katastematic” pleasure, having to do with the removal of pain, is the necessary pleasure pertaining both to the process of removing pain and to its result, namely the absence of pain, while “kinetic” pleasure is an unnecessary pleasure having nothing to do with the removal of pain, e.g. it starts after pain has been removed. If my analysis and interpretation prove correct, the two conventional classifications - “kinetic-katastematic” and “necessary-unnecessary” - turn out to be referring to the same phenomenon and are aspects of one classification. Moreover, this new interpretation resolves some of the main problems arising from our testimonia concerning “kinetic” and “katastematic” pleasures. (shrink)

TThis paper aims to evidence the inherently metonymic nature of co-speech gestures. Arguing that motivation in gesture involves iconicity (similarity), indexicality (contiguity), and habit (conventionality) to varying degrees, it demonstrates how a set of metonymic principles may lend a certain systematicity to experientially grounded processes of gestural abstraction and enaction. Introducing visuo-kinetic signs as an umbrella term for co-speech gestures and signed languages, the paper shows how a frame-based approach to gesture may integrate different cognitive/functional linguistic and semiotic accounts of (...) metonymy (e.g., experiential domains, frame metonymy, contiguity, and pragmatic inferencing). The guiding assumption is that gestures metonymically profile deeply embodied, routinized aspects of familiar scenes, that is, the motivating context of frames. The discussion shows how gestures may evoke frame structures exhibiting varying degrees of groundedness, complexity, and schematicity: basic physical action and object frames; more complex frames; and highly abstract, complex frame structures. It thereby provides gestural evidence for the idea that metonymy is more basic and more directly experientially grounded than metaphor and thus often feeds into correlated metaphoric processes. Furthermore, the paper offers some initial insights into how metonymy also seems to induce the emergence of schematic patterns in gesture which may result from action-based and discourse-driven processes of habituation and conventionalization. It exemplifies how these forces may engender grammaticalization of a basic physical action into a gestural marker that shows strong metonymic form reduction, decreased transitivity, and interacting pragmatic functions. Finally, addressing basic metonymic operations in signed lexemes elucidates certain similarities regarding sign constitution in gesture and sign. English and German multimodal discourse data as well as German Sign Language (DGS) are drawn upon to illustrate the theoretical points of the paper. Overall, this paper presents a unified account of metonymy’s role in underpinning forms, functions, and patterns in visuo-kinetic signs. (shrink)

Enzyme engineering allows to explore sequence diversity in search for new properties. The scientific literature is populated with methods to create enzyme libraries for engineering purposes, however, choosing a suitable method for the creation of mutant libraries can be daunting, in particular for the novices. Here, we address both novices and experts: how can one enter the arena of enzyme library design and what guidelines can advanced users apply to select strategies best suited to their purpose? Section (...) I is dedicated to the novices and presents an overview of established and standard methods for library creation, as well as available commercial solutions. The expert will discover an up‐to‐date tool to freshen up their repertoire (Section I) and learn of the newest methods that are likely to become a mainstay (Section II). We focus primarily on in vitro methods, presenting the advantages of each method. Our ultimate aim is to offer a selection of methods/strategies that we believe to be most useful to the enzyme engineer, whether a first‐timer or a seasoned user. (shrink)

This paper aims to examine the awesome, almost spiritual feeling I experience as an?extreme spectator? while watching Kelly Slater ride the monstrous waves of Pipeline. Drawing on the aesthetics of Kant and Schopenhauer, I examine the experience of the sublime and how it, in conjunction with the perceived kinetic melody of Slater's movements and his karmic connection to the environment in which he thrives, gives rise to the deeply felt awe of the extreme spectator. My intention is to use Slater's (...) case as a paradigm that can be applied to many other athletic performances which share the characteristics discussed in the paper. (shrink)

The multiplicity of deubiquitinating enzymes (DUBs) encoded by vertebrate genomes is partly attributable to whole genome duplication events that occurred early in chordate evolution. By surveying the literature for the largest family of DUBs (the ubiquitin-specific proteases), extensive functional redundancy for duplicated genes has been confirmed as opposed to singletons. Dramatically conflicting results have been reported for loss of function studies conducted through RNA interference as opposed to inactivating mutations, but the contradictory findings can be reconciled by a recently proposed (...) compensatory mechanism involving nonsense-mediated RNA degradation. Duplicated genes are often inactivated to become pseudogenes, and it is proposed that such is the fate of the USP15 gene of zebrafish, a commonly used model system. As it is reviewed here, these observations have implications not only for the interpretation of model system phenotypes but also for therapeutic interventions designed to target DUBs. (shrink)

The filamentous and branched thallus of Antithamnion plumula is constitued of two different kinds of branches with apical growth: the cladomial axes with a continuous or indefinite growth, and the pleuridia with a limited growth. The size of the pleuridia depends on their position with respect to the lateral cladomial axes.The growth kinetics of 35 pleuridia were analysed using Nelder's generalized logistics. Each sigmoidal curve, which was divided into four growth stages from the instantaneous acceleration variations, was thus characterized (...) by ten kinetic parameters: lengths at the time of the changes in growth stage, durations of the growth stages and maximum growth rate. (shrink)

A companion paper explored the role of intuition in the genesis of an alternative theory for the secretion of pancreatic digestive enzymes, looking through the lens of three philosophers/historians of science. Gerald Holton, the last scholar, proposed that scientific imagination is shaped by a number of thematic presuppositions, which function largely below awareness. They come in pairs of opposites that alternately gain cultural preeminence. The current paper examines three thematic presuppositions inherent to both the generally accepted model for digestive (...) class='Hi'>enzyme secretion and most consciousness-centered views of higher-level cognition—discreteness, reduction, and simplicity. Since they often build on each other, together they are referred to as the simplicity worldview . Also considered are the three opposite thematic assumptions inherent to both the alternative model for digestive enzyme secretion and intuition-friendly views of higher-level cognition—the continuum, holism, and complexity—together referred to as the complexity worldview . The article highlights the potential importance to scientific knowledge of this currently less favored worldview. (shrink)

In this essay, the first statistical and stochastic treatments of chemical dynamics are analyzed and discussed, in particular the diffusive description of chemical reactions. The first part of the paper introduces the historical and methodological basis of the theories about stochastic processes and diffusion as well as their lesser-known applications in chemical kinetics, which were advanced by Jens Anton Christiansen (1888–1969). In the second, part we will focus our attention on the early works of Oskar Benjamin Klein (1894–1977) and (...) Hendrik Anton Kramers (1894–1952) on electrolytes and the latter’s more mature work, which completes and gives a firm theoretical background to Christiansen’s description. (shrink)

This book offers a comprehensive exploration of geochemical kinetics--the application of chemical kinetics to geological problems, both theoretical and practical.

A model for kinetics of circular substrate cleavage by restriction endonuclease was formulated. The aim of the analysis of the model was to extract kinetic constants for all target sites from time- dependence of fragment concentration in reaction products. That was proved to be possible for molecules with an odd number of fragments only. A symmetry of the molecules with an even number of fragment is the cause. A solution for molecules with an odd number of fragments was found (...) and methods for dealing with the other molecules were suggested. (shrink)

This article examines the role of philosophy in the development of the kinetic theory of gases. Two opposing accounts of this role, by Peter Clark and John Nyhof, are discussed and criticized. Contrary to both accounts, it is argued that philosophical views of scientists can fundamentally influence the results of their scientific work. This claim is supported by a detailed analysis of the philosophical views of Maxwell and Boltzmann, and of their work on the kinetic theory, especially concerning the so-called (...) specific heat anomaly. It leads to the conclusion that the scientific development of the kinetic theory cannot be understood without taking into account the role of philosophy. (shrink)

The idea of the right to mobility has been fundamental to modern Western citizenship and is expressed in many legal and government documents. Although there is widespread acceptance regarding the importance of mobility in older adults, there have been few attempts to develop ethical and theoretical tools to portray mobility equalities in old age. This paper develops a novel conceptualisation of kinetic values focusing on older adults whose ability to move has been restricted for internal and external reasons. Informed by (...) the phenomenological theory of kinaesthesia, I suggest that kinetic values are related to four principal dimensions: self-motion, being-moved, co-motion, and forced movement. I assume that these dimensions can address the key dilemma of human dignity among older adults who suffer from losing their autonomy and agency through their mobility impairments and who are at risk of being confined to their homes. To concretise the formulation of kinetic values, I study movement as part of technological equipment and urban infrastructure to examine what kinds of kinetic values mobility services and assistive robots convey for older adults in smart urban environments. By bridging disciplines, the phenomenological approach provides a novel understanding of mobility and the interplay among assistive technologies, kinaesthesia, and urban technological infrastructure. The approach suggests that kinetic values should be interpreted more comprehensively so that kinaesthesia can become better identified as a positive life-promoting practice. (shrink)

When rates of transcription from specific genes change, delays of variable length intervene before the corresponding mRNAs and proteins attain new levels. For most mammalian genes, the time required to complete transcription, processing, and transport of mRNA is much shorter than the period needed to achieve a new, steady‐state level of protein. Studies of inducible genes have shown that the period required to attain new levels of individual mRNAs and proteins is related to their unique half‐lives. The basis for this (...) is a physical principle that predicts rates of accumulation of particles in compartmental systems. The minimum period required to achieve a new level is directly proportional to product half‐lives because rates of decay control the ratio between the rate of synthesis and the concentration of gene products at steady state. This kinetic model suggests that sensitivity of gene products to degradation by ribonucleases and proteinases is an important determinant of the time scale of gene expression. (shrink)