There has been considerable discussion lately of the concept of open systems, which has revealed that different participants are using the terms ?openness? and ?closure? in different ways. The purpose of this paper is to address issues of meaning that arise in this particular discourse, with a view to clarifying both conflicts in usage and the underlying issues involved. We explore the different meanings of openness and closure extant in the literature, as applied at the ontological and epistemological levels, focusing (...) on our own use of the terms in relation to that which prevails in neoclassical economics on the one hand and to the use made of them by Tony Lawson and other critical realists on the other. (shrink)
In my 1983 book, Macroeconomics after Keynes, I claimed that much that was original in Keynes was to be found not at the level of theory but in his method. Shortly afterwards, Sheila Dow's book Macroeconomic Thought (1985) introduced those of us who are not specialist methodologists to what she called the ?mode of thought?. In that book, and subsequently, it has become clear that differences in approach between those who take their inspiration from Keynes and Kalecki and those I (...) shall loosely describe as neoclassicists lie at the level of mode of thought. Almost all post?Keynesians say that Keynes's General Theory is founded on a concern with time, uncertainty and organicism ? features of Keynes's mode of thought. Yet, as far as I know, no one has shown precisely what the relationships are between the identifiable aspects of Keynes's mode of thought and his method and theory. This is the task that this paper sets itself. I identify four key theoretical contributions and their corollaries, and show how they are related to the deeper levels of method and mode of thought. This exercise is contrasted with the three?level structure of typical neoclassical macroeconomic theory. The underlying purpose is to help modern theory develop in a fruitful way. (shrink)
Nanostructured materials should present a good resistance to irradiation because the large volume fraction of grain boundaries can be an important sink for radiation-induced defects. The objective of the present study is to experimentally investigate the irradiation impact on the microstructure and mechanical properties in nanostructured materials. Nickel and Cu-0.5Al2O3 specimens were synthesized by electro deposition (ED) and severe plastic deformation (SPD). Mean grain size of the unirradiated specimen is about 30?nm for the ED Ni and about 115?nm for the (...) SPD Ni. 590?MeV proton irradiation and 840?keV nickel ion irradiation were conducted at room temperature. Vickers hardness measurements and transmission electron microscope observation were performed to examine the impact of irradiation on nanocrystalline materials. It appears that the irradiation induced microstructure in Ni and in Cu-0.5Al2O3, which leads to hardening, consists exclusively of stacking fault tetrahedra. Their density appears much lower than in the case of coarser grained material. These results, experimentally showing the resistance of nanostructured material to radiation damage, are presented here. (shrink)
The microstructural modifications due to irradiation in hcp pure metals and their consequences on the mechanical properties have been investigated. Experimental results for proton-irradiated pure polycrystalline titanium are presented and discussed. Samples have been irradiated with 590?MeV protons to a low dose range at two different temperatures, room temperature and 523?K. Defect sizes and densities as a function of dose have been determined by means of transmission electron microscopy observations, and hardening has been measured from uniaxial tensile stress?strain curves. The (...) dose dependence of the irradiation hardening has been found to depend strongly on the investigated temperatures. These results are discussed in terms of the main deformation mechanism operating at each temperature. (shrink)
We present a comprehensive dislocation dynamics (DD) study of the strength of stacking fault tetrahedra (SFT) to screw dislocation glide in fcc Cu. Our methodology explicitly accounts for partial dislocation reactions in fcc crystals, which allows us to provide more detailed insights into the dislocation?SFT processes than previous DD studies. The resistance due to stacking fault surfaces to dislocation cutting has been computed using atomistic simulations and added in the form of a point stress to our DD methodology. We obtain (...) a value of 1658.9 MPa, which translates into an extra force resolved on the glide plane that dislocations must overcome before they can penetrate SFTs. In fact, we see they do not, leading to two well differentiated regimes: (i) partial dislocation reactions, resulting in partial SFT damage, and (ii) impenetrable SFT resulting in the creation of Orowan loops. We obtain SFT strength maps as a function of dislocation glide plane-SFT intersection height, interaction orientation, and dislocation line length. In general SFTs are weaker obstacles the smaller the encountered triangular area is, which has allowed us to derive simple scaling laws with the slipped area as the only variable. These laws suffice to explain all strength curves and are used to derive a simple model of dislocation?SFT strength. The stresses required to break through obstacles in the 2.5?4.8-nm size range have been computed to be 100?300 MPa, in good agreement with some experimental estimations and molecular dynamics calculations. (shrink)
Large-scale molecular dynamics of cascade production of the primary damage state are performed in nanocrystalline nickel with an average grain diameter of 12?nm and primary knock-on atom kinetic energies ranging from 5 to 30?keV. The role of the grain boundary during the cascade production of irradiated NC Ni is discussed in terms of grain-boundary structure. It is shown that regions of misfit in the grain boundaries can absorb self-interstitials and that stacking-fault tetrahedra are formed in the neighbourhood of the grain (...) boundary. (shrink)
Irradiation induces the formation of stacking fault tetrahedra (SFTs) in a number of fcc metals, such as stainless steel and pure copper. In order to understand the role of the material's parameters on this formation, pure Cu, Ni, Pd and Al, having a respective stacking fault energy of 45, 125, 180 and 166?mJ?m?2, have been irradiated with high energy protons to a dose of about 10?2?dpa at room temperature. The irradiation-induced microstructure has been investigated using transmission electron microscopy. All irradiated (...) metals but Al present SFTs. The proportion of perfect, truncated and grouped SFTs has been determined. The SFT energy as a function of size has been calculated using elasticity of the continuum, with respect to the energy of a number of other possible defect configurations. It appears that the key parameters are the stacking fault energy and the shear modulus. Their implication on the formation and stability of the SFTs is discussed. (shrink)
Single-crystal nickel was irradiated with 590?MeV protons to 10?1?dpa at room temperature. Irradiated and unirradiated tensile samples were deformed and relaxation tests were performed at temperatures between 77 and 423?K. The tests show a strong temperature dependence of the flow stress for samples irradiated to 0.1?dpa as compared to the unirradiated case. Unirradiated and irradiated deformed microstructures were investigated by transmission electron microscopy. The initial plastic deformation of the samples irradiated at 0.1?dpa shows strain localization in the form of defect (...) free channels, over the temperature range from 77 to 293?K. Deformation processes are analysed through the determination of the activation energies of the deformation mechanisms as deduced from relaxation tests. The activation energy has an approximate value of 0.5?eV in unirradiated samples. In the irradiated samples it is suggested that multiple deformation processes are operative in the temperature range from 77 to 423?K. (shrink)
This article to honor Professor Yolanda Ruano is divided into two parts. In the first one, I argue about the criticisms she realized to my book on the goddess Fortune in advancing her own analysis of the complex relationship between reason and fortune in Western thought. In the second part, from the standpoint of the “iconic turn” in the humanities and social sciences, I analyze the specific case of the rise and downfall of the goddess Fortune in the political iconography (...) of the city of Berlin. Throughout the nineteenth century the goddess Fortune disappeared of Berlin and was replaced by the goddess Nike or Victoria, popularly interpreted as an Angel of Victory. This is the framework of the childhood of Walter Benjamin, who later expressed his view on history with a completely different angel, the Angelus Novus by Paul Klee. (shrink)
Previous perceptual research with black-capped and mountain chickadees has demonstrated that these species treat each other’s namesake chick-a-dee calls as belonging to separate, open-ended categories. Further, the terminal dee portion of the call has been implicated as the most prominent species marker. However, statistical classification using acoustic summary features suggests that all note-types contained within the chick-a-dee call should be sufficient for species classification. The current study seeks to better understand the note-type based mechanisms underlying species-based classification of (...) the chick-a-dee call by black-capped and mountain chickadees. In two, complimentary, operant discrimination experiments, both species were trained to discriminate the species of the signaller using either entire chick-a-dee calls, or individual note-types from chick-a-dee calls. In agreement with previous perceptual work we find that the D note had significant stimulus control over species based discrimination. However, in line with statistical classifications, we find that all note-types carry species information. We discuss reasons why the most easily discriminated note-types are likely candidates to carry species based cues. (shrink)
Chicks reared in the absence of light and rat pups reared without extra stimulation fail to exhibit behavioral laterality, implying that a threshold amount of environmental stimulation is necessary for the brain to follow an asymmetry pathway. Reverse asymmetry has been reported in the chick, but not the rat, though a sex difference resembling reverse asymmetry has been found in the rat.
Summary Ferdinand von Mueller (1825?96), the German-born Government Botanist of Victoria from 1853 until his death, and concurrently Director of the Melbourne Botanic Garden from 1857 until 1873, was a prolific systematic botanist, but also heavily involved in public educational activities. He conceived of the Garden as an educative place of recreation, but ultimately lost control over it. His loss did not stop his popular writing and lecturing, especially in areas related to the application of botany in horticulture, agriculture, (...) and forestry. The structure of his introductory school text?very different from the intensely logical grammar-like botany texts of the period?owed much to his political masters, but it is characterized by careful attention to language and locality. Mueller's work represents a consistent and pervasive example of attention to the ?public understanding of science? that resonates with the concerns of early twenty-first-century funders of scientific research. (shrink)
McGovern, Kevin A recent move in Victoria to decriminalise abortion invites reflection on this issue. In this article, I review the history which has led to the present situation, and then offer four comments.
Mediante un análisis del último libro publicado por Victoria Camps, El Gobierno de las emociones , Premio Nacional de Ensayo 2012, se pretende resaltar, siguiendo su argumentación, la importancia de la motivación para el comportamiento moral. La motivación hace uso de razones instrumentales para potenciar emociones adecuadas y llegar así a la formación del carácter moral, a la autoestima moral. De este modo, se concluye que los sentimientos son educables, pero tenemos que buscar el clima propicio para ello y (...) esto forma parte de la tarea de la ética. (shrink)
Newly-hatched domestic chicks, reared with identical objects, when presented with sets of 3 vs. 2 objects disappearing one-by-one behind separate screens, spontaneously inspected the screen occluding the larger set; even when the continuous variables (area or perimeter) were controlled for (Rugani et al., 2009). Here, using a similar paradigm, we investigated the ability of chicks to perform addition on larger sets of objects. Chicks imprinted on 5 identical objects, were presented at test with 6 vs. 9 objects which disappeared one-by-one (...) (Exp.1). In Exp. 2, the same overall number of objects (15) was used, but employing an increased ratio, i.e. 5 vs. 10. In both experiments, when continuous variables were not made equal, chicks spontaneously inspected the screen occluding the larger set. However, when the size of the objects was adjusted so as to make the total surface area or perimeter equal for the two sets, chicks did not exhibit any preference. Lack of choice in the control conditions could be due to a combination of prefences; to rejoin the larger numerousness as well as the bigger objects (Rugani et al., 2010). In Exp. 3, chicks were familiarized, during imprinting, with objects of various dimensions, in an attempt to reduce or suppress their tendency to approach objects larger than the familiar ones. Again chicks failed to choose at test between 5vs.10 objects when continuous variables were made equal. Results showed that chicks, after a one by one presentation of a large number of objects, rejoined the larger set. In order to choose the larger set, chicks estimated the objects in the two sets and then compared the outcomes. However, differently to what has been described for small numerousness, chicks succeeded only if non-numerical cues as well as numerical cues were available. This study suggests that continuous variables are computed by chicks for sets of objects that are not present at the same time and that are no longer visible at the time of choice. (shrink)
El presente artículo aborda las connotaciones y los fundamentos de la paráfrasis cum canere vellem en Serv. Ecl. 6. 3. El análisis del sentido del verbo volo en este contexto y la confrontación del pasaje con Serv. Ecl. 6. 5 revelan que Servio interpreta la frase cum canerem reges et proelia como referencia a un temprano empeño de Virgilio en componer poesía épica, del que pronto desistió. Esta interpretación está condicionada por la idea de que la secuencia cronológica Églogas - (...) Geórgicas - Eneida tiene un correlato jerárquico, idea que se funda en noticias biográficas y en la teoría de la tripertita varietas. This paper focuses on the connotations and grounds of the paraphrase cum canere vellem in Serv. Ecl. 6. 3. The analysis of the sense of verb volo within this context, as well as the confrontation between that passage and Serv. Ecl. 6. 5, show that Servius interprets the clause cum canerem reges et proelia as a reference to Virgil's early endeavor to compose an epic poem, from which he shortly desisted. This interpretation is conditioned by the idea that the chronological sequence Eclogues - Georgics - Aeneid has a hierarchical correlate, an idea which is founded on biographical information and the theory of tripertita varietas. (shrink)