Ethylene (C2H4) is a gaseous plant hormone produced by higher and lower (green) plants and, when grown on appropriate substrates, also by fungi, yeasts and bacteria. Ethylene is involved in many developmental processes in plants and is biologically active in trace amounts (10 – 100 nl/I of air) that may be present in the outside air due to industrial air pollution(1). Fruit ripening and flower senescence especially, in a variety of commercially important crops, are dramatically stimulated by ethylene. Following characterization (...) of the genes coding for the key enzymes in ethylene biosynthesis, i.e. ACC synthase and ACC oxidase, it has become clear that their expression is regulated in a complex manner involving developmental, hormonal and tissue‐specific factors. This was recently very elegantly demonstrated for the expression of ACC oxidase genes in developing petunia flowers by Tang et al.(2). The spatial and temporal expression patterns, especially in the reproductive organs, suggest a hitherto unknown role for ethylene in reproductive processes such as the self‐incompatible response and the secretion of cellular exudate by the stigma and nectary. (shrink)

Programmed cell death (PCD) is a process aimed at the removal of redundant, misplaced, or damaged cells and it is essential to the development and maintenance of multicellular organisms. In contrast to the relatively well‐described cell death pathway in animals, often referred to as apoptosis, mechanisms and regulation of plant PCD are still ill‐defined. Several morphological and biochemical similarities between apoptosis and plant PCD have been described, including DNA laddering, caspase‐like proteolytic activity, and cytochrome c release from mitochondria. Reactive oxygen (...) species (ROS) have emerged as important signals in the activation of plant PCD. In addition, several plant hormones may exert their respective effects on plant PCD through the regulation of ROS accumulation. The possible plant PCD regulators discussed in this review are integrated in a model that combines plant‐specific regulators with mechanisms functionally conserved between animals and plants. BioEssays 25:47–57, 2003. © 2002 Wiley Periodicals, Inc. (shrink)

Phillips & Silverstein emphasize the gain-control properties of NMDA synapses in cognitive coordination. We endorse their view and suggest that NMDA synapses play a crucial role in biased attentional competition and (visual) working memory. Our simulations show that NMDA synapses can control the storage rate of visual objects. We discuss specific predictions of our model about cognitive effects of NMDA-antagonists and schizophrenia.

More involvement of sub-Saharan African countries in biomedical studies, specifically in genetic research, is needed to advance individualized medicine that will benefit non-European populations. Missing infrastructure, cultural and religious beliefs as well as lack of understanding of research benefits can pose a challenge to recruitment. Here we describe recruitment efforts for a large genetic study requiring three-generation pedigrees within the Yoruba homelands of Nigeria. The aim of the study was to identify genes responsible for keloids, a wound healing disorder. We (...) also discuss ethical and logistical considerations that we encountered in preparation for this research endeavor. (shrink)

Purpose This study aims to explore how the public perceives the effectiveness of surveillance technology, and how people’s views on privacy and their views on effectiveness are related. Likewise, it looks at the relation between perceptions of effectiveness and opinions on the acceptable cost of surveillance technology. Design/methodology/approach For this study, surveys of Dutch students and their parents were conducted over three consecutive years. Findings A key finding of this paper is that the public does not engage in a trade-off (...) neither with regard to privacy-effectiveness nor with effectiveness-cost, but rather expects all three elements to be achieved simultaneously. This paper also found that the correlation between perceived effectiveness and perceived privacy was stronger for parents than for students. Research limitations/implications Participants for this study were exclusively in The Netherlands. Survey questions on the effectiveness of surveillance technology focused on one type of technology, and on private mobile device use in two scenarios. Social implications The public’s perceptions of the effectiveness of surveillance technology potentially influence its acceptance of the technology, which, in turn, can affect the legitimacy and use of the technology. Originality/value Within the much-discussed privacy-security debate lies a less-heard debate – that of the effectiveness of the surveillance technology in question. The public is one actor in this debate. This study examines the public’s perceptions of this less-heard debate. (shrink)

In numerous studies, experimental economists have documented the fact that people tend to propose that divisible goods be divided equally. It has often been proposed, most notably by the sociobiologists, that this tendency may have a biological basis, and might be the product of evolution and natural selection. ;My dissertation addresses methodological and philosophical problems that arise in the course of establishing this naturalistic claim. Specifically, the focus of this dissertation is on the project of using evolutionary game theory to (...) model the emergence of behavioral norms in a population. ;Chapter 1 briefly surveys the experimental economics literature that supports the existence of such behavioral propensities, and gives an overview of the dissertation. Chapter 2 introduces the fundamental concepts of game theory and evolutionary game theory. Chapter 3 argues that certain robustness failures may be overcome if group selection mechanisms are incorporated into the evolutionary models. Chapter 5 defends Peter Railton's causal theory of explanation, and argues that it best accommodates the dynamical models of evolutionary game theory. Chapter 6 addresses the question of whether a descriptive account of the origins of our moral intuitions is relevant to the normative project of identifying our moral obligations, and critiques arguments by Peter Singer and Peter Unger that our moral intuitions lack justification. (shrink)

The Marine Biological Laboratory in Woods Hole, MA provided opportunities for women to conduct research in the late 19th and early 20th century at a time when many barriers existed to their pursuit of a scientific career. One woman who benefited from the welcoming environment at the MBL was Mary Jane Hogue. Her remarkable career as an experimental biologist spanned over 55 years. Hogue was born into a Quaker family in 1883 and received her undergraduate degree from Goucher College. She (...) went to Germany to obtain an advanced degree, and her research at the University of Würzburg with Theodor Boveri resulted in her Ph.D.. Although her research interests included experimental embryology, and the use of tissue culture to study a variety of cell types, she is considered foremost a protozoologist. Her extraordinary demonstration of chromidia in the life history of a new species of Flabellula associated with diseased oyster beds is as important as it is ignored. We discuss Hogue’s career path and her science to highlight the importance of an informal network of teachers, research advisors, and other women scientists at the MBL all of whom contributed to her success as a woman scientist. (shrink)

Cassirer, E. Antropología filosófica.--Vecchio, G. del. El hombre y la naturaleza.--Jaspers, K. La pregunta acerca del hombre.--Marx, K. Existencia y conciencia.--Mounier, E. Las estructuras del universo personal.--Ortega y Gasset, J. Pasado y porvenir para el hombre actual.--Platón. Fedón.--Santayana, G. El nacimiento de la razón. Schaff, A. El marxismo y la filosofía del hombre.--Shorojova, E. V. Lo general humano y lo clasista en la concienia del hombre.--Spear, O. Animal rationale.--Spengler, O. El advenimiento del hombre. Wahl, J. Algunas observaciones acerca del hombre.

Our senses are constantly stimulated in our daily lives but we have only a limited understanding of how they affect our cognitive processes and, especially, our autobiographical memory. Capitalizing on a public science event, we conducted the first empirical study that aimed to compare the relative influence of the five senses on the access, temporal distribution, and phenomenological characteristics of autobiographical memories in a sample of about 400 participants. We found that the access and the phenomenological features of memories varied (...) as a function of the type of sensory cues, but not their temporal distribution. With regard to their influence on autobiographical memory, an overlap between some senses was found, with on one hand, olfaction and taste and, on the other, vision, audition, and touch. We discuss these findings in the light of theories of perception, memory, and the self, and consider methodological implications of the sensory cuing technique in memory research, as well as clinical implications for research in psychopathological and neuropsychological populations. (shrink)

The necessary appearance of Clifford algebras in the quantum description of fermions has prompted us to re-examine the fundamental role played by the quaternion Clifford algebra, C 0,2 . This algebra is essentially the geometric algebra describing the rotational properties of space. Hidden within this algebra are symplectic structures with Heisenberg algebras at their core. This algebra also enables us to define a Poisson algebra of all homogeneous quadratic polynomials on a two-dimensional sub-space, $\mathbb{F}^{a}$ of the Euclidean three-space. This enables (...) us to construct a Poisson Clifford algebra, ℍ F , of a finite dimensional phase space which will carry the dynamics. The quantum dynamics appears as a realisation of ℍ F in terms of a Clifford algebra consisting of Hermitian operators. (shrink)

Dass "Wahrnehmung" sich historisch verändert, ist in den gegenwärtigen Debatten ebenso präsent wie die Einsicht, dass "Geschichte" selbst hochgradig wahrnehmungsabhängig ist. Die Autoren dieses Bandes erörtern die wechselseitigen Beziehungen von Wahrnehmung und Geschichte nicht allein theoretisch, sondern vorrangig materialbezogen - mit Blick auf konkrete Fallbeispiele. Das Spektrum der Beiträge reicht von der Erörterung der historischen Vermittlungsfunktion technischer Medien und verschiedener Künste bis zur Frage, welcher Logik Wahrnehmung und Vergessen der jüngsten und eigenen Geschichte unterliegen. Michel Foucault und Marshall McLuhan werden (...) als Vordenker einer solchen Aisthesis materialis, zu der hier "Markierungen" geliefert werden, begriffen. Beide kommen mit einem programmatischen Text auch selbst zu Wort. (shrink)

This article shows that those texts, attributed to Ernst Mach, that reject relativity theory are posthumous forgeries.