bluuebunny/crossref_metadata_2025 huggingface dataset:
Relativity, contradictions, and confusions
Authors: Rebigsol Cameron
Published: August 2003

The derivation leading to the formulation of Lorentzian transformation in special relativity is actually a duplication of an ancient “miracle” in algebra: 2x−x=0, 2x=x, 2=1. Dominated by such a mathematical confusion, relativity displays fundamental uncertainty in understanding physics. As such, with equations, it claims to have “discovered” two speed limits in nature: the speed of light in the vacuum space and the speed of light at the mass center of a material body. Needless to say, these two speed limits repel each other, not to mention that the second speed limit is even against nature. Relativity then further extends this confusion and uncertainty in physics to make up many self‐contradicting concepts. These concepts include the so‐called homogeneous gravitational field and the idea of having (circumference/diameter)>3.1415926… for a spinning circle. With the same mathematics guiding to its “success”, however, relativity presents no homogeneous gravitational field, but a monster that must be called a homogeneously inhomogeneous field for its appropriation. Based on the same erroneous mathematics, relativity must force itself to have (circumference/diameter)<3.1415926… for a spinning circle. With the idea of a homogeneous gravitational field, relativity believes that it can establish the validity of the so‐called Principle of Equivalence for the legitimacy of general relativity. However, Newtonian mechanics, supported by the close orbital movements of numerous heavenly objects, must witness the nonexistence of such a “principle” in nature.
Determining reaction abilities of sewing machine operators in joining curved seams
Authors: Firsˇt Rogale Snjezˇana , Dragcˇevic´ Zvonko , Rogale Dubravko
Published: August 2003

In accordance with his/her psycho‐physical abilities and degree of skill, regulating system in the operator's brain will match the speed of sewing operations, e.g. actual machine stitching speed, using a simple movement of the foot, to adapt it to his/her sensory and motoric reaction abilities. Workpiece in sewing is fed employing three degrees of freedom movement, i.e. using three independent regulating circuits: position of the seam, edges and workpiece layer length. Cybernetic bases of the regulating system man‐machine‐workpiece are presented, as well as the development of the necessary and maximum possible sewing machine operator's reactions in joining curved seams. The procedure is explained by constructing a mathematical model and obtaining the equations used in calculating necessary and maximum operator's reaction abilities. Measurements necessary were performed in the Department of Clothing Technology, Faculty of Textile Technology, University of Zagreb, using modern measuring equipment while garment‐sewing processes were recorded under actual in‐plant conditions. The results obtained were computer‐processed and a 3D graphic representation was obtained together with a mathematical model appropriate to calculate interdependence of the mentioned parameters. Appropriate software package was developed, which allows a quick, accurate and continuous determination of normal machine‐hand times, as dependent on all the influential parameters.
Load‐adapted 3D‐reinforcement by means of function‐adjusted ready‐making process
Authors: Herzberg Claudia , Krzywinski Sybille , Rödel Hartmut
Published: August 2003

Complex material requirements for high‐technology applications increasingly demand the use of hybrid material structures with properties tailored to the lines of loading. Textile‐reinforced multilayer composite structures are particularly suitable for the production of component structures in an optimised lightweight construction. In the loading case, however, delaminating phenomena occur between the individual layers due to the low interlaminar shear strength. The appropriate techniques and machines of the ready‐made‐clothing technology allow the specific sewing‐up of the semifinished textile products into a three‐dimensionally reinforced multilayer composite structure; the setting of a load‐adapted and failure‐tolerant characteristic of properties being possible in the z‐direction through a versatile variation of sewing parameters. Moreover, the sewing technology makes possible a ready‐made‐clothing‐technological preassembly of components of semi‐finished products, and thus can perform position‐fixing functions in the consolidation of the composites. The ready‐made‐clothing process is divided into sub‐processes like product development, preparation of cutting, cutting, connecting and forming as well as packaging and shipping. The technical procedures and machines applied are chosen from economic aspects. Besides the large number of pieces, extreme thickness of the textile products of up to 20 mm and the required sewing precision demand precise and reproducible manufacturing processes.
Mechanical properties of sewing stitch performed in frozen state
Authors: Nikolic´ Gojko , Sˇomođi Zˇeljko , Franulic´ Sˇaric´ Diana
Published: August 2003

The proposed solution for increased automation in clothing production by freezing the textile involves sewing operations in frozen state. The realistic applicability of such technology could be limited, amongst other issues, by the possible loss of mechanical properties of the sewing stitch performed in that way. This work represents an experimental investigation for the evaluation of the influence of textile freezing to possible changes of mechanical properties with respect to the normally performed sewing stitch. A series of standard extension tests are done on specimens of sewing stitches performed both in frozen state and in usual way for comparison. The differences in the results are analysed statistically for a representative textile material.
The evaluation of fused knitted systems stability
Authors: Strazdiene Eugenija , Gutauskas Matas
Published: August 2003

The aim of the presented research is to apply the method of punch deformation for the simulation of textile systems behaviour in serve conditions and on the basis of it create original method and find new criteria for shape stability evaluation. The research was done with the help of three devices of punch loading originally created at Kaunas University of Technology (Lithuania), which were attached to the standard tensile testing machine. Creep tests were performed by a special device, clamping radius of which was R=56.5 mm. Creep process was controlled up to the stabilisation of shells height, i.e. after t=48 h. Tests were carried out in wet and dry states of the specimen. Two different types of textile systems (I+K and K+I) composed of two layers were investigated (where K – outer material; I – interlining).
Engineering the drapability of textile fabrics
Authors: Stylios George K. , Powell Norman J.
Published: August 2003

The drape attributes of fabrics, number of folds, depth of folds and evenness of folds were measured together with the drape coefficient. The relationship between these measurements and the subjective evaluation of the fabric drape was modelled for each end‐use on a neural network using back propagation, which can correctly predict the grades of 90 per cent of the samples. The relationship between the drape attributes and fabric bending, shear and weight was also modelled using neural networks. It was found that using the natural logarithm of the material property divided first by the weight of the fabric produced the most predictive model. Together, these models provide a powerful predictive tool to determine both the drape attributes and the drape grade from the mechanical properties of a fabric. The accuracy of the prediction of this system was found to be 83 per cent overall. Combining this with a novel feedback system, the drape grade or drape attributes of a fabric can be modified to fit the customer requirements and then the changes to the material properties required to achieve them can be determined.
Investigations of the relation between fabric mechanical properties and behaviour
Authors: Zavec Pavlinic´ Daniela , Geršak Jelka
Published: August 2003

In transforming fabrics into garment it is necessary to know, besides the manner of processing, the behaviour of the fabric in particular manufacturing processes. It is necessary to define why and how fabrics behave in a particular way when exposed to various strains. The answers to these questions are obtained by investigating fabric mechanics, as non‐linear mechanical fabric properties at lower strains, which is the case in transforming fabrics into garments. The area to be investigated is quite wide and the investigations presented here deal only with the most important elastic strains occurring in processing fabrics into garments, such as tensile, pressure, shear and bending, as each individual type of strain bears specific importance in studying fabric behaviour, as well as in garment quality control. Strains impacting the fabric, i.e. the reaction of the fabric to these strains, are presented through the parameters of mechanical properties. A relation is also explained between characteristic histeresis curves and fabric behaviour in real garment manufacturing processes, obtained through recording fabric behaviour in particular garment manufacturing processes. Results obtained through the investigations of mechanical properties of the fabrics analysed and their behaviour in garment manufacturing processes helped to determine the so‐called critical, or border values for particular parameters of mechanical properties.
Determination of the sewing thread friction coefficient
Authors: Zˇunicˇ‐Lojen Darja , Gersˇak Jelka
Published: August 2003

The quality of sewing threads, as defined by their mechanical and physical properties, is connected with seam quality and seam strength. Seam quality and seam appearance depend mainly on the following sewing thread properties: bending properties, dimensional stability, thread twist and twist direction, fineness, regularity and surface properties on used fibres. The friction on the guide elements of the sewing machine depends on the surface treatment of the thread and affects the tensile force during the stitch formation process. It is important therefore, to know the friction coefficient when choosing the appropriate sewing thread. This contribution presents the influence of the sewing thread movement velocity over the guide element, the influence of the contact angle between the thread and guide element and the influence of the guide element material on the friction coefficient. The results of the research show that on increasing the thread velocity over the guide element, the friction coefficient slightly increases, whilst with the increase of the contact angle between the thread and guide element, the friction force exceedingly decreases. Furthermore, the results show that the friction coefficients using the steel guide are lower when compared with the ceramic guide. The behaviour of the sewing thread during the sewing process, can be concluded, based on these statements.
Testing electrostatic properties of polyurethane coated textiles used for protective clothing
Authors: Hainsˇ Nada , Frisˇcˇic´ Vera , Gordosˇ Dubravka
Published: August 2003

The objective of the study was to test the electrostatic properties of textiles used for protective clothing worn in flammable and potentially explosive environment. The protective clothing is intended for multi‐use and, apart from wear and stretching during use, it is also exposed to impacts of various cleaning agents. The testing was carried out in accordance with EN 1149‐1; 1995 specifying requirements for electrostatic properties and testing methods for protective clothing to be worn in specific situations. The objective was to test whether there was a likelihood of fire due to the electric discharge. EN 1149‐1 requires measuring surface resistance at 25±2 per cent relative humidity and temperature of 23±1°C. Measurements were taken on knitting of varying materials coated with polyurethane. The knittings used were made of polyamide, polyester and cotton. All materials were coated with the same polyurethane coating. All samples were tested for surface resistance before and after five dry‐cleanings and machine washings. In addition to the required European standard, surface resistance was also measured at the following relative humidity: 35, 45, 55 and 65 per cent. The results were processed by the correlation analysis and shown graphically.
Surface roughness of heat protective clothing textiles
Authors: Militky´ Jirˇí , Bajzík Vladimír
Published: August 2003

The surface roughness is one of the main parts of hand prediction. Classical method of surface roughness measurements is based on the surface profile measurement. Characteristic of roughness is then variation coefficient of surface profile (surface height variation). The main aim of this work is to estimate the surface profile complexity by using variogram (structure function). The surface profile variation is classified to the group according to short‐ and long‐range dependence. The concept of fractal dimension is proposed especially for long‐term correlation cases. The applicability of the proposed approach is demonstrated on the typical heat protective clothing fabrics and compared with the results of surface roughness evaluated by the KES system.
Influence of the sterilisation process on the tactile feeling of surgical gowns
Authors: Philippe Flora , José Abreu Maria , Schacher Laurence , Adolphe Dominique C. , Elisabete Cabeço Silva Maria
Published: August 2003

More and more disposable goods are available in surgical rooms. Rules and standards have been proposed in order to prevent infection from patient to surgical team and vice versa. A proposed mandatory European standard prEn 13795 “Surgical drapes, gowns and clear air suits used as medical devices, for patients, clinical staff and equipment”, is being developed by the Committee of European Normalisation and specifies the basic performance requirements and test methods for single‐use and reusable materials after sterilisation process. Therefore, the performances of the surgical gowns demand a balance between barrier and comfort properties. In comfort evaluation, tactile feeling is one of the most primary and important aspects with regard to the grading of the products. Therefore, the influence of the sterilisation process on the tactile perception is important to be evaluated. Subsequently, the final aim of this paper is to contribute to the knowledge of influence of sterilisation treatment on the tactile perception.
Numerical simulation of textile flexibility testing
Authors: Šomodi Željko , Hursa Anica , Rogale Dubravko
Published: August 2003

A non‐linear numerical simulation of a standard procedure for textile flexibility testing is performed using discretised beam bending model. Geometric non‐linearity due to large deflections is traced using incremental method. Linear moment‐curvature response is assumed, as well as constant curvature of a finite element of the beam. Numerical procedure is incorporated into a PC programme producing graphical results for the deformed shape of the specimen, non‐linear load‐deflection diagrams and internal force distributions in deformed state. Finally, the method is applied to compute the flexural stiffness of textile materials from the data produced by the standard procedure for flexibility testing.
The physical properties of the surface of apparel made from flax and polyester fibres
Authors: Zimniewska Małgorzata , Michalak Marina , Krucińska Izabella , Więcek Bogusław
Published: August 2003

In this paper, the clothes made of synthetic and natural fibres were tested. The characteristics of selected physical parameters such as temperature, electrical resistance, thermal resistance of fabrics used for tested clothes have been presented. The electrostatical charge and temperature distribution of clothes were investigated on human body. The temperature distribution and the coefficient of heat transmission were measured by a new thermovision method.
Evolutionary algorithms aided textile design
Authors: Grundler Darko , Rolich Tomislav
Published: August 2003

Fabric design has always been a matter of inspiration, depending mostly upon man's ingenuity and creativity. The authors suggest that creation of fabric patterns using evolution algorithms, which can not only help in improving design created by man, but also make the procedure semi‐automatic, meaning much less dependent upon the designer himself/herself. Evolution algorithm based software offers a wide range of fabric patterns and is also able to create new ones based on the user's choice. The procedure can also be of considerable help to professional designers, as it can offer patterns they would not or could not create themselves. The system described is inexpensive and can be used on IBM compatible personal computers. It is user‐friendly and can be implemented with no previous preparation on the part of the user. The results of preliminary investigations suggest a practical applicability of the software.
Electronic customer relationship management
Authors: Fjermestad Jerry , Romano Nicholas C.
Published: September 2003

Electronic customer relationship management (eCRM) has become the latest paradigm in the world of customer relationship management. Recent business surveys suggest that up to 50 per cent of such implementations do not yield measurable returns on investment. A secondary analysis of 13 case studies suggests that many of these limited success implementations can be attributed to usability and resistance factors. The objective of this paper is to review the general usability and resistance principles in order to build an integrative framework for analyzing eCRM case studies. The conclusions suggest that if organizations want to get the most from their eCRM implementations they need to revisit the general principles of usability and resistance and apply them thoroughly and consistently.
Imagined Country: National Environmental Ideologies in School Geography Textbooks
Authors: Morgan John
Published: August 2003

This essay considers the “imagined geographies” of Britain found in school geography textbooks in the postwar period. The first part of the essay considers the role that school geography plays in processes of social reproduction. It suggests that textbooks represent an important resource through which meanings are negotiated in the everyday lives of teachers and students. The second part of the essay discusses some of the specific “national environmental ideologies” found in geographies of Britain. The essay concludes with a discussion of the wider context in which geographies of Britain are taught in schools.
Indigenous Professionalization: Transnational Social Reproduction in the Andes
Authors: Laurie Nina , Andolina Robert , Radcliffe Sarah
Published: August 2003

Indigenous professionalization is occurring throughout Latin America at an increasing pace as new careers open up in social development. Under what is heralded as socially inclusive neoliberalism, a “development with identity” paradigm is producing new university courses focused on indigenous issues. Influenced by discourses of social and human capital and addressing intersections of multiculturalism and development, these courses mobilize and help shape definitions of indigeneity; they also create spaces where donors and indigenous activists contest and debate understandings of development. Operating in a range of institutions, indigenous professionalization courses are led by a small elite group of academics and practitioners who move between programs and countries. Students also move transnationally. We argue that these courses, their classrooms and their curricula are intent on understanding intercultural situations transnationally, galvanizing international funding and support from bilateral and multilateral agencies as well as local and state actors. The social reproduction of indigenous professionalization is therefore transnational, yet grounded. At times, indigenous professionalization is socially reproduced by jumping scale; at other times, it works through established social and spatial hierarchies. This essay examines how indigenous professionalization is socially reproduced as a contested process through which notions of “good” and “culturally appropriate” development are constituted and consolidated.
Producing the Future: Getting To Be British
Authors: Lave Jean
Published: August 2003

Enduring struggles between different historical capitalisms are concretely instantiated in the British “colony” in Porto, Portugal. In contention is the future of the community and its identity as a venerable port merchant or multinational corporate enclave. Residents, both long‐ and short‐term, work to produce the future place and identity of their children. Church, club, and—above all—schools are the focus of their clashes and also of this essay, as it explores the articulation of practices that help to produce those futures.
Domesticating Birth in the Hospital: “Family‐Centered” Birth and the Emergence of “Homelike” Birthing Rooms
Authors: Fannin Maria
Published: August 2003

Childbirth is both an embodied and symbolic process, and the home and the hospital have been the shifting and contested sites of childbirth in contemporary discourses of birth in the United States. I argue that the economic and cultural imperatives of deregulation and downsizing of US health‐care produce new spaces of domesticity and birthing bodies. Through an examination of the relatively recent transformations of hospital space into “homelike” birthing rooms, I propose a more nuanced understanding of how discursive and material shifts in the practices and sites of birth create new spatialities and subjectivities. The emergence of the “homelike” hospital room situates the production of birth spaces at the nexus of debates around domesticity, the body, the politics of reproduction, and the economics of health care in the United States.
Adolescent Latina Bodyspaces: Making Homegirls, Homebodies and Homeplaces
Authors: Hyams Melissa
Published: August 2003

This essay examines the local, everyday practices of heteropatriarchal power—dominating and resisting power, through which young Latina women negotiate teenage, sexual and gender subjectivity and spatial ordering of young heterosexual bodies. Their negotiations are shaped by and give shape to the material, discursive and representational social spaces of Los Angeles, worsening “landscapes of neglect” attributable to the changing geographies of private and public investment. Their narratives convey and construct a visceral experience of being tied, materially and discursively, to homely spaces as young carers, and their struggle to untie their competencies to the private, domestic sphere, or “inside,” and their vulnerabilities to the public sphere, or “outside.” In their struggle, the young Latinas variously reproduce, rework and resist the dominant norms and materiality of local places and their dispositionality in bodily terms.
Of Fictional Cities and “Diasporic” Aesthetics
Authors: George Rosemary Marangoly
Published: August 2003

This essay considers the work of social reproduction as it unfolds within the cultural realm in both national and diasporic contexts. Beginning with a discussion of the creation of Malgudi—the quintessential Indian hometown created in the 1930s by one of India's most venerated writers, R K Narayan—I go on to argue that in the preindependence days, this Indian small town was created from an aesthetic position not unlike that of present‐day diasporic artists. I then look at the novels of South Asian‐American writer Indira Ganesan and the paintings by South Asian‐American artist Arijit Sen to document the ways in which the works attempt to map alternative articulations of the space of home and community in a diasporic context. Together, these imaginary hometowns do the work of reproducing a viable social sphere through creative work that overcomes the constraints of colonial rule (in Narayan's case) and immigration (in Ganesan's and Sen's work).
Valuing Childcare: Troubles in Suburbia
Authors: Pratt Geraldine
Published: August 2003

I unravel a complex weave of practices in metropolitan Vancouver that lead to the persistent devaluation of childcare. These include the assumptions that women alone are responsible for paying for childcare, the difficulty that parents have determining how skills and educational qualifications relate to high‐quality childcare and the tendency to insert childcare workers into various familial scenarios that cheapen the costs of their own social reproduction. I look closely at outer suburbs, because this is where wages for childcare are lowest and parents experience the most difficulty in arranging dependable care. Although various women doing paid domestic work are positioned differently, they share with each other the effects of gendered assumptions about domestic work.
Toque una Ranchera, Por Favor
Authors: Cravey Altha J.
Published: August 2003

This paper explores the literal spaces of transnational social reproduction for Latinos and Latinas in central North Carolina and the US South. Examining these spaces and circuits of social reproduction can enhance our understanding of globalization by making globalization processes at once less abstract and less indisputable. Attention to social reproduction is important for understanding and theorizing globalization and, more significantly, for imagining and constructing alternative forms of globalization.

Inspired to pursue certain freedoms and immediate goals, transnational migrants live and breath alternative models of globalization in their everyday activities. Responding less to neo‐liberal and more to human‐centered values, transnational migrants demonstrate that different principles can guide the construction of contemporary globalizations. Ethnographic evidence from Mexican transnational migrants suggests that the intimate and distant social connections that constitute Latinos' translocal way of living help to facilitate the very same globalizing labor markets that entice and propel migrants to seek “greener pastures” in the US South.
Human Smuggling, the Transnational Imaginary, and Everyday Geographies of the Nation‐State
Authors: Mountz Alison
Published: August 2003

This essay outlines a conceptual approach to everyday geographies of the nation‐state. The case study analyzed is the cross‐institutional response to human smuggling in Canada. The essay draws on qualitative research with government and nongovernment actors who responded to the arrival of four boats carrying migrants smuggled from Fujian, China to British Columbia in 1999. Findings regarding the everyday institutional contexts of work in the field of immigration prompt deconstruction of the conceptual boundaries that surround governance in more abstract epistemologies of the state. This poststructural approach to geographies of the nation‐state pays particular attention to the role of identity and language in the categorization of im/migrants and provokes contemplation of the transnational imaginary of the nation‐state from the standpoint of policing international borders.
Fodor on concepts and Frege Puzzles
Authors: Aydede Murat
Published: August 2003

Fodor characterizes concepts as consisting of two dimensions: one is content, which is purely denotational/broad, the other the Mentalese vehicle bearing that content, which Fodor calls the mode of presentation (MOP), understood “syntactically.” I argue that, so understood, concepts are not interpersonally shareable; so Fodor’s own account violates what he calls the Publicity Constraint in his (1998) book. Furthermore, I argue that Fodor’s non‐semantic solution to Frege cases succumbs to the problem of providing interpersonally applicable functional roles for MOPs. This is a serious problem because Fodor himself has argued extensively that if Fregean senses or meanings are understood as functional/conceptual roles, then they can’t be public, since, according to Fodor, there are no interpersonally applicable functional roles.
Conceptual Relativism
Authors: Brueckner Anthony
Published: August 2003

What is conceptual relativism? Several formulations of the idea that truth, or existence, is somehow relative to conceptual schemes are considered. All are found lacking.
David Hume’s Reductionist Epistemology of Testimony
Authors: Faulkner Paul
Published: August 2003

David Hume advances a reductionist epistemology of testimony: testimonial beliefs are justified on the basis of beliefs formed from other sources. This reduction, however, has been misunderstood. Testimonial beliefs are not justified in a manner identical to ordinary empirical beliefs; it is true, they are justified by observation of the conjunction between testimony and its truth, but the nature of the conjunctions has been misunderstood. The observation of these conjunctions provides us with our knowledge of human nature and it is this knowledge which justifies our testimonial beliefs. Hume gives a naturalistic rather than a sceptical account of testimony.
The Paradox of Belief Instability and a Revision Theory of Belief
Authors: Lee Byeong
Published: August 2003

The epistemic paradox of ‘belief instability’ has recently received notable attention from many philosophers. In this paper I offer a new proposal, which I call a ‘revision theory of belief’. This theory is in many respects an application of Gupta’s and Belnap’s revision theory of truth. They argue that the Liar paradox arises because our notion of truth is circular. I offer a similar proposal for handling the paradox of belief instability. In particular, I argue that our notion involved in the paradox of belief instability is circular, and this circularity of belief is the source of the paradox.
Wittgenstein on the metaphysics of the self: the dialectic of solipsism in philosophical investigations
Authors: Minar Edward H.
Published: August 2003

Wittgenstein’s later efforts to exorcise the attractions of solipsism involve descriptions of the uses of ‘I’ which may be taken to show that ‘I’ does not refer in its philosophically most salient uses. This point of “grammarrdquo;, however, would not by itself provide a direct refutation of solipsism; Philosophical Investigations ¶¶398‐410, of which this paper is a reading, traces a complex dialectic by which Wittgenstein elicits and questions the solipsist’s commitments. In challenging the intelligibility of the solipsist’s starting‐points, Wittgenstein raises a forceful demand for an explanation of the motivations behind metaphysical inquiry into the nature of the self.
Socrates’ Moral Intellectualism
Authors: Rickless Samuel C.
Published: August 2003

In the Protagoras, Socrates appears to affirm and defend a paradoxical doctrine: the unity of virtue. Plato scholars do not agree on how the doctrine should be understood. Some, following Vlastos (1972), take Socrates to hold that the virtues are biconditionally related, i.e. that anyone who has one of the virtues has them all. Others, following Penner (1973), take Socrates’ position to be that the names of the virtues all refer to the same thing, namely virtue. In this paper, I argue that both of these interpretations are mistaken: the main thesis of the Protagoras is, very simply, that each of the virtues is a kind of knowledge or wisdom.
Rawls, the difference principle, and economic inequality
Authors: Schaller Walter E.
Published: August 2003

Rawls’s theory of justice has been criticized for allowing individuals by their own voluntary choice to make themselves members of the ‘least advantaged’ class and thereby eligible, albeit undeservedly, for the benefits mandated by the Difference Principle. I argue, first, that this criticism overlooks the fact that the Difference Principle applies only to the lifetime expectations of representative persons and, second, that it is possible to implement the Difference Principle (and the social minimum) through policies that do not create work disincentives or require making objectionable moral judgments about who is and who is not deserving of assistance.
Conserved Role of nanos Proteins in Germ Cell Development
Authors: Tsuda Masayuki , Sasaoka Yumiko , Kiso Makoto , Abe Kuniya , Haraguchi Seiki , Kobayashi Satoru , Saga Yumiko
Published: August 2003

In
Drosophila
, maternally supplied Nanos functions in the migration of primordial germ cells (PGCs) into the gonad; in mice, zygotic genes are involved instead. We report the cloning and the functional analyses of
nanos2
and
nanos3
in mice. These genes are differentially expressed in mouse PGCs.
nanos2
is predominantly expressed in male germ cells, and the elimination of this gene results in a complete loss of spermatogonia. However,
nanos3
is found in migrating PGCs, and the elimination of this factor results in the complete loss of germ cells in both sexes. Hence, although mice and flies differ in their mechanisms for germ cell specification, there seems to be conserved function for nanos proteins among invertebrates and vertebrates.
Single-Molecule Measurement of Protein Folding Kinetics
Authors: Lipman Everett A. , Schuler Benjamin , Bakajin Olgica , Eaton William A.
Published: August 2003

In order to investigate the behavior of single molecules under conditions far from equilibrium, we have coupled a microfabricated laminar-flow mixer to a confocal optical system. This combination enables time-resolved measurement of Förster resonance energy transfer after an abrupt change in solution conditions. Observations of a small protein show the evolution of the intramolecular distance distribution as folding progresses. This technique can expose subpopulations, such as unfolded protein under conditions favoring the native structure, that would be obscured in equilibrium experiments.
A Perspective on Enzyme Catalysis
Authors: Benkovic Stephen J. , Hammes-Schiffer Sharon
Published: August 2003

The seminal hypotheses proposed over the years for enzymatic catalysis are scrutinized. The historical record is explored from both biochemical and theoretical perspectives. Particular attention is given to the impact of molecular motions within the protein on the enzyme's catalytic properties. A case study for the enzyme dihydrofolate reductase provides evidence for coupled networks of predominantly conserved residues that influence the protein structure and motion. Such coupled networks have important implications for the origin and evolution of enzymes, as well as for protein engineering.
Cleavage of
Arabidopsis
PBS1 by a Bacterial Type III Effector
Authors: Shao Feng , Golstein Catherine , Ade Jules , Stoutemyer Mark , Dixon Jack E. , Innes Roger W.
Published: August 2003

Plant disease-resistance (R) proteins are thought to function as receptors for ligands produced directly or indirectly by pathogen avirulence (Avr) proteins. The biochemical functions of most Avr proteins are unknown, and the mechanisms by which they activate R proteins have not been determined. In
Arabidopsis
, resistance to
Pseudomonas syringae
strains expressing AvrPphB requires RPS5, a member of the class of R proteins that have a predicted nucleotide-binding site and leucine-rich repeats, and PBS1, a protein kinase. AvrPphB was found to proteolytically cleave PBS1, and this cleavage was required for RPS5-mediated resistance, which indicates that AvrPphB is detected indirectly via its enzymatic activity.
Helical Conformation of Alkanes in a Hydrophobic Cavitand
Authors: Trembleau Laurent , Rebek Julius
Published: August 2003

Alkanes adopt extended conformations in solution that minimize steric interactions and maximize surface area. Folding can reduce the amount of hydrophobic surface exposed to solvent, but sterically unfavorable gauche interactions result. However, we found that the alkyl chains of two common surfactants in aqueous solution adopt helical conformations when bound within a synthetic receptor. The receptor recognizes the helical alkane better than the extended conformation, even though 2 to 3 kilocalories per mole of strain is introduced. The proper filling of space and burial of hydrophobic surface drive the molecular recognition between the receptor and the coiled alkane.
Synthesis of Carbenes Through Substitution Reactions at a Carbene Center
Authors: Merceron-Saffon Nathalie , Baceiredo Antoine , Gornitzka Heinz , Bertrand Guy
Published: August 2003

An (amino)(phosphino) carbene can be transformed into (amino)(phosphonio) carbenes, which undergo nucleophilic intermolecular as well as intramolecular substitution reactions at the carbene center. A variety of carbenes can be synthesized starting from a single carbene precursor. The resulting gamut of electronic and steric effects possible should open the way not only to a detailed study of the mechanism, but also to the subsequent improvement of catalytic reactions that involve carbene-transition metal complexes.
Representation of Action Sequence Boundaries by Macaque Prefrontal Cortical Neurons
Authors: Fujii Naotaka , Graybiel Ann M.
Published: August 2003

Complex biological systems such as human language and the genetic code are characterized by explicit markers at the beginning and end of functional sequences. We report here that macaque prefrontal cortical neurons exhibit phasic peaks of spike activity that occur at the beginning and endpoint of sequential oculomotor saccade performance and have the properties of dynamic start- and end-state encoders accompanying responses to sequential actions. Sequence bounding may thus reflect a general mechanism for encoding biological information.
Melt Segregation and Strain Partitioning: Implications for Seismic Anisotropy and Mantle Flow
Authors: Holtzman B. K. , Kohlstedt D. L. , Zimmerman M. E. , Heidelbach F. , Hiraga T. , Hustoft J.
Published: August 2003

One of the principal means of understanding upper mantle dynamics involves inferring mantle flow directions from seismic anisotropy under the assumption that the seismic fast direction (olivine
a
axis) parallels the regional flow direction. We demonstrate that (i) the presence of melt weakens the alignment of
a
axes and (ii) when melt segregates and forms networks of weak shear zones, strain partitions between weak and strong zones, resulting in an alignment of
a
axes 90° from the shear direction in three-dimensional deformation. This orientation of
a
axes provides a new means of interpreting mantle flow from seismic anisotropy in partially molten deforming regions of Earth.
Measurement of Single-Molecule Resistance by Repeated Formation of Molecular Junctions
Authors: Xu Bingqian , Tao Nongjian J.
Published: August 2003

The conductance of a single molecule connected to two gold electrodes was determined by repeatedly forming thousands of gold-molecule-gold junctions. Conductance histograms revealed well-defined peaks at integer multiples of a fundamental conductance value, which was used to identify the conductance of a single molecule. The resistances near zero bias were 10.5 ± 0.5, 51 ± 5, 630 ± 50, and 1.3 ± 0.1 megohms for hexanedithiol, octanedithiol, decanedithiol, and 4,4′ bipyridine, respectively. The tunneling decay constant (β
N
) for
N
-alkanedithiols was 1.0 ± 0.1 per carbon atom and was weakly dependent on the applied bias. The resistance and β
N
values are consistent with first-principles calculations.
Persistence Without Pathology in Phosphoglycan-Deficient
Leishmania major
Authors: Späth Gerald F. , Lye Lon-Fey , Segawa Hiroaki , Sacks David L. , Turco Salvatore J. , Beverley Stephen M.
Published: August 2003

Leishmania
infections involve an acute phase of replication within macrophages, typically associated with pathology. After recovery parasites persist for long periods, which can lead to severe disease upon reactivation. Unlike the role of host factors, parasite factors affecting persistence are poorly understood.
Leishmania major
lacking phosphoglycans (
lpg2
-
) were unable to survive in sand flies and macrophages, but retained the ability to persist indefinitely in the mammalian host without inducing disease. The
L. major lpg2
-
thus provides a platform for probing parasite factors implicated in persistence and its role in disease and immunity.
Production of Complex Human Glycoproteins in Yeast
Authors: Hamilton Stephen R. , Bobrowicz Piotr , Bobrowicz Beata , Davidson Robert C. , Li Huijuan , Mitchell Teresa , Nett Juergen H. , Rausch Sebastian , Stadheim Terrance A. , Wischnewski Harry , Wildt Stefan , Gerngross Tillman U.
Published: August 2003

We report the humanization of the glycosylation pathway in the yeast
Pichia pastoris
to secrete a human glycoprotein with uniform complex N-glycosylation. The process involved eliminating endogenous yeast glycosylation pathways, while properly localizing five active eukaryotic proteins, including mannosidases I and II,
N
-acetylglucosaminyl transferases I and II, and uridine 5′-diphosphate (UDP)-
N
-acetylglucosamine transporter. Targeted localization of the enzymes enabled the generation of a synthetic in vivo glycosylation pathway, which produced the complex human
N
-glycan
N
-acetylglucosamine
2
-mannose
3
-
N
-acetylglucosamine
2
(GlcNAc
2
Man
3
GlcNAc
2
). The ability to generate human glycoproteins with homogeneous
N
-glycan structures in a fungal host is a step toward producing therapeutic glycoproteins and could become a tool for elucidating the structure-function relation of glycoproteins.
A Demographic View of Limits on Life-Span
Authors: Mueller Laurence D.
Published: August 2003

Longevity
The Biology and Demography of Life Span.
By James R. Carey
. Princeton University Press, Princeton, NJ, 2003. 304 pp. $75, £49.95. ISBN 0-691-08848-9. Paper, $29.95, £19.95. ISBN 0-691-08849-7.

Drawing on his life-history studies of Mediterranean fruit flies, Carey presents a framework for determining the key factors that govern mortality and life-span in humans and other animals.
To Prove the Optimal Packing
Authors: Zeilberger Doron
Published: August 2003

Kepler's Conjecture
How Some of the Greatest Minds in History Helped Solve One of the Oldest Math Problems in the World.
By George G. Szpiro
. Wiley, New York, 2003. 304 pp. $24.95, C$38.95, £18.50. ISBN 0-471-08601-0.

Writing for a popular audience, Szpiro provides an account of the history of efforts--from Kepler to Tom Hales--to prove that the densest packing of spheres is given by the face-centered cubic arrangement.
Knee disorders in the general population and their relation to occupation
Authors: Baker P , Reading I , Cooper C , Coggon D
Published: September 2003

Background:Hospital based studies of occupational risk factors for knee disorders are complicated by the possibility of selective referral to hospital of people whose work is made difficult by their symptoms.

Aims:To explore the extent of such bias and to assess the association of meniscal injury with occupational activities.

Methods:A questionnaire was mailed to a community sample of 2806 men aged 20–59 years in southern England. This asked about lifetime occupational and sporting activities, and any history of knee symptoms lasting 24 hours or longer. Rates of hospital referral were compared in symptomatic men according to their occupational activities. In a nested case-control investigation, the occupational activities of 67 men who reported meniscectomy were compared with those of 335 controls.

Results:Among 1404 men who responded to the questionnaire, the lifetime prevalence of knee symptoms was 54%, and in 70% of cases the symptoms had started suddenly, usually while playing sport. Symptomatic men whose work entailed kneeling or squatting were more likely to be referred to an orthopaedic surgeon than the average (28% and 31% versus 24%), especially if they experienced locking of the knee (69% and 73% versus 43%). In the nested case-control study, meniscectomy was associated with playing soccer and work that involved regular kneeling or squatting.

Conclusions:Results suggest that hospital referral for knee symptoms is influenced to some extent by patients’ occupational activities. Playing soccer is confirmed as a strong risk factor for knee cartilage injury.
Iteration Theory: Dynamical Systems and Functional Equations
Authors: Balibrea F. , Reich L. , Smítal J.
Published: August 2003

The aim of this paper is to give an account of some problems considered in the past years in the setting of Discrete Dynamical Systems and Iterative Functional Equations, some new research directions and also state some open problems.
Linear Chaos on Fréchet Spaces
Authors: Bonet J. , Martínez-Giménez F. , Peris A.
Published: August 2003

This is a survey on recent results about hypercyclicity and chaos of continuous linear operators between complete metrizable locally convex spaces. The emphasis is put on certain contributions from the authors, and related theorems.
One-Dimensional Semiconjugacy Revisited
Authors: Alves J. F. , Sousa Ramos J.
Published: August 2003

Let f be a piecewise monotone interval map with positive topological entropy h(f)= log (s). Milnor and Thurston showed that f is topological semiconjugated to a piecewise linear map having slope s. Here we prove that these semiconjugacies are the eigenvectors of a certain linear endomorphism associated to f. Using this characterization, we prove a conjecture presented by those authors.
A Note on Sarkovskiĭ's Theorem in Connected Linearly Ordered Spaces
Authors: Alcaraz D. , Sanchis M.
Published: August 2003

We prove that, for a connected linearly ordered space L, the following conditions are equivalent: (1) L satisfies Sarkovskiĭ's Theorem, (2) there exist turbulent functions on L, and (3) there exists a compact subspace of L which satisfies Sarkovskiĭ's Theorem. Our results are applied in two ways. Firstly, we show that there exist connected linearly ordered spaces without infinite minimal sets; secondly, for each cardinal number λ of uncountable cofinality, we construct a connected linearly ordered space L such that: (1) L is a compact nonfirst countable space satisfying Sarkovskiĭ's Theorem, (2) L admits a dense first countable subset, and (3) the density of L is λ.
On Iterated Positive Schwarzian Derivative Maps
Authors: Oliveira Henrique , Sousa Ramos J.
Published: August 2003

We study the behavior of a unimodal map in two parameters, one of the parameters varies the sign of the Schwarzian derivative the second the value of the maximum. We characterize the behavior of the different dynamics in the parameter space.
Generalized Specification Property and Distributional Chaos
Authors: Balibrea F. , Schweizer B. , Sklar A. , Smítal J.
Published: August 2003

Let f be a continuous map from a compact interval into itself. Continuing the work begun by Schweizer and Smítal [1994], we prove that the restriction of f to any basic set (i.e. any nonsolenoidal, infinite, maximal ω-limit set) satisfies a generalization of the specification property. We apply this generalization to establish several conjectures made in the abovementioned paper, e.g. the fact that distributional chaos is stable.
Extreme Chaos and Transitivity
Authors: Babilonová-Štefánková Marta
Published: August 2003

In the eighties, Misiurewicz, Bruckner and Hu provided examples of functions chaotic in the sense of Li and Yorke almost everywhere. In this paper we show that similar results are true for distributional chaos, introduced in [Schweizer & Smítal, 1994]. In fact, we show that any bitransitive continuous map of the interval is conjugate to a map uniformly distributionally chaotic almost everywhere. Using a result of A. M. Blokh we get as a consequence that for any map f with positive topological entropy there is a k such that fk is semiconjugate to a continuous map uniformly distributionally chaotic almost everywhere, and consequently, chaotic in the sense of Li and Yorke almost everywhere.