oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Individuality as an illusion  [PDF]
Adonai S. Sant'Anna
Physics , 2004,
Abstract: Elementary particles in quantum mechanics (QM) are indistinguishable when sharing the same intrinsic properties and the same quantum state. So, we can consider quantum particles as non-individuals, although non-individuality is usually considered as a consequence of the formalism of QM, since the entanglement of states forbids any labelling process. We show how to consider non-individuality as one of the basic principles of QM, instead of a logical consequence. The advantages of our framework are discussed as well. We also show that even in classical particle mechanics it is possible to consider the existence of non-individual particles. One of our main contributions is to show how to derive the apparent individuality of classical particles from the assumption that all physical objects are non-individuals.
Law and individuality  [cached]
D.F.M. Strauss
Koers : Bulletin for Christian Scholarship , 2007, DOI: 10.4102/koers.v72i1.189
Abstract: The main contours of the history of philosophical and scientific conceptions of law and individuality are portrayed. This includes an account of perspectives and views found in ancient Greece, the Graeco-Roman world, the medieval speculation and, via the Renaissance, in early modern developments that were continued in the Enlightenment era, in Romanticism and historicism, and were eventually manifested in the linguistic turn. What is important for a proper understanding of modern law conceptions is an acknowledgement of the all-pervading influence of modern nominalism. This orientation was characterised by employing two related distinctions, namely the distinction between conceptual knowledge and concept-transcending knowledge, and that between rationalism and irrationalism. From a systematic point of view, various aspectual terms provide a frame of reference for the idea of a law of nature as a compound basic concept of science. Special attention is given to the nature of normative principles and physical laws. In the last part of the article, these perspectives are applied to a brief assessment of differences and similarities in the thought of Dooyeweerd and Vollenhoven.
Development of Biomimetic Needle-like Apatite Nanocrystals by a Simple New Method
Jie WEI,Yubao LI,Yi ZUO,Xueling PENG,Li ZHANG,
Jie WEI
,Yubao LI,Yi ZUO,Xueling PENG and Li ZHANGResearch Center for Nano-Biomaterials,Sichuan University,Chengdu,China

材料科学技术学报 , 2004,
Abstract: A new method of calcium nitrate and sodium phosphate as reactants was employed to prepare biomimetic apatite nanocrystals by a simple heating treatment in water. The structure and properties of the apatite crystals were investigated by TEM, XRD, IR, ICP and TG. It is found that the apatite nanocrystals contain OH-, CO32-, Na and HPO~- ions in their crystal structure. The crystal water is removed during heating from 200℃ to 400℃. CO32-and HPO~- are decomposed at 600℃ to 800℃, also there is lattice water lost at this temperature stage. The morphology of the apatite nanocrystals is needle-like with a length less than 80 nm. The size and crystallinity of the apatite nanocrystals increase with water treatment temperature and time. Compared to the apatite crystals sintered at 800℃, water treated apatite nanocrystals are poorly crystallized apatite. The results indicate that the apatite nanocrystals have similarity in composition, structure, morphology and crystallinity to that of bone apatite crystals. It can be used to make apatite crystals/polymer biomimetic bone repair materials or for other biomedical applications.
The role of vocal individuality in conservation
Andrew MR Terry, Tom M Peake, Peter K McGregor
Frontiers in Zoology , 2005, DOI: 10.1186/1742-9994-2-10
Abstract: Signals can contain information useful to conservation [1,2]. Until recently, communication behaviour had a limited role in conservation, being restricted to enhancing captive breeding programs [3] or use in species counts [4]. However, knowledge of how individuals within a population communicate and what they are communicating can generate information ranging from measures of habitat use to genetic fitness [2,5] that can be applied to conservation and that may neither be possible nor desirable to extract using other methods. In this review we shall concentrate on a subsection of communication behaviour that underlies most attempts to gain useful information from signalling, namely individuality. We discuss the different applications and types of information that can be extracted using vocal individuality. Further, we consider the different methods currently applied and the results gained with different taxonomic groups. Finally, we discuss some of the limitations and future directions that this technique can take. As a consequence of our area of research we have concentrated our discussion on the role of acoustic vocal individuality in conservation, although the principles involved equally apply to other signalling modalities, with the possible exception of chemical signals where the techniques may currently be lacking.A pre-requisite for discrimination and individual recognition is that, in the signals being used, there should be low within-individual variation and high between-individual variation [6,7]. Many studies have shown the presence of individually distinctive vocal features in a wide range of animal species and it seems that vocal individuality is most likely a feature of all vocally active species and is caused by a series of genetic, developmental and environmental factors [8,9]. The level of individuality and the difficultly in extracting and using it will differ between species and we discuss these issues later in the review (also see [10-12]).When d
The Information Theory of Individuality  [PDF]
David Krakauer,Nils Bertschinger,Eckehard Olbrich,Nihat Ay,Jessica C. Flack
Quantitative Biology , 2014,
Abstract: We consider biological individuality in terms of information theoretic and graphical principles. Our purpose is to extract through an algorithmic decomposition system-environment boundaries supporting individuality. We infer or detect evolved individuals rather than assume that they exist. Given a set of consistent measurements over time, we discover a coarse-grained or quantized description on a system, inducing partitions (which can be nested). Legitimate individual partitions will propagate information from the past into the future, whereas spurious aggregations will not. Individuals are therefore defined in terms of ongoing, bounded information processing units rather than lists of static features or conventional replication-based definitions which tend to fail in the case of cultural change. One virtue of this approach is that it could expand the scope of what we consider adaptive or biological phenomena, particularly in the microscopic and macroscopic regimes of molecular and social phenomena.
Deposition of Apatite on Carbon Nanofibers in Simulated Body Fluid  [PDF]
Seiichi Taruta,Kazuki Kidokoro,Tomohiko Yamakami,Tomohiro Yamaguchi,Kunio Kitajima,Morinobu Endo,Naoto Saito
Journal of Nanomaterials , 2011, DOI: 10.1155/2011/935320
Abstract: Carbon nanofibers (CNFs) were soaked in 1.5 simulated body fluid (1.5?SBF) in which inorganic ion concentrations are 1.5 times as high as those in the standard SBF. The influence of the CNFs content in 1.5?SBF and pretreatment of the CNFs on the biomimetical deposition of apatite were investigated. The spherical bone-like apatite particles were deposited on the pristine CNFs soaked in 1.5?SBF. Amount of deposited apatite per a unit of CNFs increased with a decrease in the CNFs content in 1.5?SBF, and it decreased markedly when the CNFs were pretreated with concentrated sulfuric acid/nitric acid (3?:?1 v/v) mixture for longer periods. Such results suggest that too many nucleation sites of apatite, which were functional groups, such as carboxyl and hydroxyl groups, existed on the CNFs in the 1.5?SBF, and most embryos formed on the sites could not grow to critical nuclei and furthermore did not grow to apatite. 1. Introduction Carbon nanotubes (CNTs) have exceptional mechanical [1–4], thermal [2, 5], and electrical properties [6, 7] and are recognized as incredible nanomaterials. Due to such superior properties, CNTs are considered to be very useful reinforcements or additives in various materials, such as plastics, metals, and ceramics, to improve properties of the materials and introduce novel functionalities. In the medical field, particularly orthopedics, CNTs are anticipated to be of use as reinforcements of various biomaterials. For instance, the mechanical strength and fracture toughness of artificial bone made of hydroxyapatite ceramics will be enhanced by combining with CNTs. In addition, CNTs have good bone-tissue compatibility, accelerate bone formation in response to rhBMP-2 [8], and promote the proliferation of osteoblastic cells [9, 10]. Therefore, CNTs are expected to be uses as scaffolds to promote and guide bone-tissue regeneration. On the other hand, it is known that apatite is biomimetically formed on the CNTs in simulated body fluid (SBF) and other solutions containing calcium and phosphate ions [11–16]. Functional groups, such as carboxyl group (?COOH), on CNTs act as nucleation sites of apatite, which induce the deposition of apatite. However, their reported apatite crystals were different in the morphology, and the deposition processes of apatite are not clear sufficiently. In this study, in order to make apatite deposit uniformly on carbon nanofibers (CNFs) which are a kind of multiwalled carbon nanotube, the CNFs were soaked in 1.5?SBF in which inorganic ion concentrations are 1.5 times as high as those in the standard SBF. And the
Surface Enamel Remineralization: Biomimetic Apatite Nanocrystals and Fluoride Ions Different Effects  [PDF]
Norberto Roveri,Elisa Battistella,Claudia Letizia Bianchi,Ismaela Foltran,Elisabetta Foresti,Michele Iafisco,Marco Lelli,Alberto Naldoni,Barbara Palazzo,Lia Rimondini
Journal of Nanomaterials , 2009, DOI: 10.1155/2009/746383
Abstract: A new method for altered enamel surface remineralization has been proposed. To this aim carbonate-hydroxyapatite nanocrystals which mimic for composition, structure, nanodimensions, and morphology dentine apatite crystals and resemble closely natural apatite chemical-physical properties have been used. The results underline the differences induced by the use of fluoride ions and hydroxyapatite nanocrystals in contrasting the mechanical abrasions and acid attacks to which tooth enamel is exposed. Fluoride ions generate a surface modification of the natural enamel apatite crystals increasing their crystallinity degree and relative mechanical and acid resistance. On the other hand, the remineralization produced by carbonate-hydroxyapatite consists in a deposition of a new apatitic mineral into the eroded enamel surface scratches. A new biomimetic mineral coating, which progressively fills and shadows surface scratches, covers and safeguards the enamel structure by contrasting the acid and bacteria attacks.
Is the individuality interpretation of quantum theory wrong ?  [PDF]
Ulf Klein
Physics , 2012,
Abstract: We analyze the question whether or not quantum theory should be used to describe single particles. Our final result is that a rational basis for such an 'individuality interpretation' does not exist. A critical examination of three principles, supporting the individuality interpretation, leads to the result that no one of these principles seems to be realized in nature. The well-known controversy characterized by the names of Einstein (EPR), Bohr and Bell is analyzed. EPR proved 'predictive incompleteness' of quantum theory, which implies that no individuality interpretation exists. Contrary to the common opinion, Bell's proof of 'metaphysical completeness' does not invalidate EPR's proof because two crucially different meanings of 'completeness' are involved. The failure to distinguish between these two meanings is closely related to a fundamentally deterministic world view, which dominated the thinking of the 19th century and determines our thinking even today.
The individuality of stem cells
Arthur D Lander
BMC Biology , 2011, DOI: 10.1186/1741-7007-9-40
Abstract: Similar things may be said about stem cells. Although not a new subject in biology, in the last decade and a half, stem cells seem truly to have exploded onto the scene of biological research (Figure 1). Not surprisingly, attitudes about stem cells have focused largely on the ways in which they are different from other cells. Thus, basic research on stem cells has been dominated by a search for explanations of properties thought to be common to stem cells, such as self-renewal, immortality, pluripotency and asymmetry of division. Yet in recent years, there has been growing awareness that such properties are not unique to stem cells, nor do all types of stem cells necessarily possess them, nor do those that possess them manifest them at all times. Such recognition that there is diversity and plasticity among types of stem cells has freed us to start paying closer attention to the diversity of behaviors displayed by individual stem cells, even within supposedly homogeneous groups.Nowhere is such individuality more evident than in clonal-analysis studies, which involve the tracking of stem cells and their offspring over time. Clonal analysis has a long history in the stem-cell field, going back to pioneering work on hematopoietic stem cells in the early 1960s [1]. Such work has always suggested that stem cells behave stochastically - essentially rolling dice at each cell division to determine whether to make two progeny that are both stem cells, two progeny that are non-stem cells, or one of each [2]. Yet for years, most biologists have espoused a deterministic view, in which stem cells all behave in predetermined ways, usually dividing asymmetrically (at least under normal circumstances), to produce one stem cell and one 'transit-amplifying cell', which then replicates itself a fixed number of times before finally differentiating [3,4].The widespread adoption by biologists of the deterministic, stem/transit-amplifying model should be seen less as an unwillingness to a
Bohm's approach and Individuality  [PDF]
P. Pylkk?nen,B. J. Hiley,I. P?ttiniemi
Physics , 2014,
Abstract: Ladyman and Ross (LR) argue that quantum objects are not individuals (or are at most weakly discernible individuals) and use this idea to ground their metaphysical view, ontic structural realism, according to which relational structures are primary to things. LR acknowledge that there is a version of quantum theory, namely the Bohm theory (BT), according to which particles do have definite trajectories at all times. However, LR interpret the research by Brown {\em et al.} as implying that "raw stuff" or {\em haecceities} are needed for the individuality of particles of BT, and LR dismiss this as idle metaphysics. In this paper we note that Brown {\em et al.}'s research does not imply that {\em haecceities} are needed. Thus BT remains as a genuine option for those who seek to understand quantum particles as individuals. However, we go on to discuss some problems with BT which led Bohm and Hiley to modify it. This modified version underlines that, due to features such as context-dependence and non-locality, Bohmian particles have a very limited autonomy in situations where quantum effects are non-negligible. So while BT restores the possibility of quantum individuals, it also underlines the primacy of the whole over the autonomy of the parts. The later sections of the paper also examine the Bohm theory in the general mathematical context of symplectic geometry. This provides yet another way of understanding the subtle, holistic and dynamic nature of Bohmian individuals. We finally briefly consider Bohm's other main line of research, the "implicate order", which is in some ways similar to LR's structural realism.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.