Zeno and Stoic Consistency

It seems that the Stoics were prepared to say two things : 1) It will in fact pay to be virtuous provided that you want to be happy; and 2) the good man will seek virtue for its own sake. Some of the apparent difficulties in reconciling these propositions may be resolved by examining the notion of seeking virtue for its own sake. What then do the Stoics say that virtue is? Any Cynic could advocate a consistent life, for the description is purely formal. But one consistent life might be set against another, and Zeno\u27s appeal to natural consistency prevents this, as well as showing exactly why virtue pays. The question could, of course, have been tackled in another way. Is there in fact more than one kind of consistent life? Zeno would certainly have agreed that there is not, but though he thought that in all but the wise inconsistency leads to conflict and misery, he did not ask such a necessary question as: Is an injury to someone else also an injury to myself? Why did he not? In part because by separating the goal (happiness) from the end (virtue) he underestimated the importance of eudaemonism in preaching a moral system to the unconverted. Or if he did not underestimate it, he kept implying that he did and that one should

Plotinus and the Value of the Human Person

Plotinus\u27 views on man and his value must be closely related to his views of the One. His first principle is radically different from that of the Platonists, Aristotelians, and Stoics who precede him. In many respects, as in all other areas of his thought, his conception is a synthesis of what went before, but it cannot be overemphasized that it is a new conception, a dynamic first principle whose character as efficient cause is to be viewed in terms of Eros and of will as much as of mind and knowledge. That being so, and man being a microcosm, one should expect to find - and we do find - a different conception of man, and, compared with Plato and Aristotle, a new intrinsic importance assigned to him. Man in Plotinus is created perfectible and valuable, but he may not live up to himself; if he does not do so, it is own fault and neither man nor gods should be held responsible. Above all, for Plotinus no saviour god is required to get us out of the troubles in which we immerse ourselves through crime and folly

Notes on Aristotle De Anima 3.5

Of all the Aristotelian doctrines perhaps the most difficult is that concerning the Active and Passive Intellects which we find in the short fifth chapter of the third book of the De Anima. Interpretations of this chapter have been almost as numerous as interpreters, and it would be naive to expect at this stage to be definitive. Nevertheless it seems that progress has been delayed in many cases by a too casual approach to what Aristotle says in the chapter itself - and this at least admits of some improvement

Bragg spectroscopic interferometer and quantum measurement-induced correlations in atomic Bose-Einstein condensates

We theoretically analyze the Bragg spectroscopic interferometer of two spatially separated atomic Bose-Einstein condensates that was experimentally realized by Saba et al. [Science 2005 v307 p1945] by continuously monitoring the relative phase evolution. Even though the atoms in the light-stimulated Bragg scattering interact with intense coherent laser beams, we show that the phase is created by quantum measurement-induced back-action on the homodyne photo-current of the lasers, opening possibilities for quantum-enhanced interferometric schemes. We identify two regimes of phase evolution: a running phase regime which was observed in the experiment of Saba et al., that is sensitive to an energy offset and suitable for an interferometer, and a trapped phase regime, that can be insensitive to applied forces and detrimental to interferometric applications.Comment: 14 pages, 3 figure

Geometry and tool motion planning for curvature adapted CNC machining

CNC machining is the leading subtractive manufacturing technology. Although it is in use since decades, it is far from fully solved and still a rich source for challenging problems in geometric computing. We demonstrate this at hand of 5-axis machining of freeform surfaces, where the degrees of freedom in selecting and moving the cutting tool allow one to adapt the tool motion optimally to the surface to be produced. We aim at a high-quality surface finish, thereby reducing the need for hard-to-control post-machining processes such as grinding and polishing. Our work is based on a careful geometric analysis of curvature-adapted machining via so-called second order line contact between tool and target surface. On the geometric side, this leads to a new continuous transition between “dual” classical results in surface theory concerning osculating circles of surface curves and oscu- lating cones of tangentially circumscribed developable surfaces. Practically, it serves as an effective basis for tool motion planning. Unlike previous approaches to curvature-adapted machining, we solve locally optimal tool positioning and motion planning within a single optimization framework and achieve curvature adaptation even for convex surfaces. This is possible with a toroidal cutter that contains a negatively curved cutting area. The effectiveness of our approach is verified at hand of digital models, simulations and machined parts, including a comparison to results generated with commercial software

Collisional excitation of doubly and triply deuterated ammonia ND2_2H and ND3_3 by H2_2

The availability of collisional rate coefficients is a prerequisite for an accurate interpretation of astrophysical observations, since the observed media often harbour densities where molecules are populated under non--LTE conditions. In the current study, we present calculations of rate coefficients suitable to describe the various spin isomers of multiply deuterated ammonia, namely the ND$_2$H and ND$_3$ isotopologues. These calculations are based on the most accurate NH$_3$--H$_2$ potential energy surface available, which has been modified to describe the geometrical changes induced by the nuclear substitutions. The dynamical calculations are performed within the close--coupling formalism and are carried out in order to provide rate coefficients up to a temperature of $T$ = 50K. For the various isotopologues/symmetries, we provide rate coefficients for the energy levels below $\sim$ 100 cm$^{-1}$. Subsequently, these new rate coefficients are used in astrophysical models aimed at reproducing the NH$_2$D, ND$_2$H and ND$_3$ observations previously reported towards the prestellar cores B1b and 16293E. We thus update the estimates of the corresponding column densities and find a reasonable agreement with the previous models. In particular, the ortho--to--para ratios of NH$_2$D and NHD$_2$ are found to be consistent with the statistical ratios

Relating the primitive hierarchy of the PREMO standard to the standard reference model for intelligent multimedia presentation systems

The need for a suitable classification of media types arises for several reasons when building or comparing multimedia systems. Within an Intelligent Multimedia Presentation Systems (IMMPS) it is necessary to formulate and encode design knowledge for decision making on the appropriate medium in which to present information and for the generation of the presentation. It is also required in order to specify interfaces to and between system components which will be employed to run a generated presentation before the user's eyes. This task is reflected in the SRM (Standard Reference Model, see this volume) for IMMPS by the Presentation Display Layer. However, the SRM does not instantiate this layer in detail, but instead refers to the PREMO ISO/IEC standard which provides a reference model for a presentation runtime environment for multimedia. PREMO already contains a set of basic structures, the so-called PREMO Primitive Hierarchy, to describe different media types. Thus the question arises, as to how far the PREMO Primitive Hierarchy could serve as a media classification for the SRM in general. In particular, this would support consistency between the design and presentation layers of the SRM if PREMO were used to instantiate the Presentation Layer. In the report, we first point to a number of typical problems with generating classifications of media types. We then provide a brief introduction to PREMO and its Primitive Hierarchy. Finally, the benefits and costs of using the PREMO primitive hierarchy for the SRM are discussed

Transition Delay Using Biomimetic Fish Scale Arrays

Aquatic animals have developed effective strategies to reduce their body drag over a long period of time. In this work, the influence of the scales of fish on the laminar-to-turbulent transition in the boundary layer is investigated. Arrays of biomimetic fish scales in typical overlapping arrangements are placed on a flat plate in a low-turbulence laminar water channel. Transition to turbulence is triggered by controlled excitation of a Tollmien-Schlichting (TS) wave. It was found that the TS wave can be attenuated with scales on the plate which generate streamwise streaks. As a consequence, the transition location was substantially delayed in the downstream direction by 55% with respect to the uncontrolled reference case. This corresponds to a theoretical drag reduction of about 27%. We thus hypothesize that fish scales can stabilize the laminar boundary layer and prevent it from early transition, reducing friction drag. This technique can possibly be used for bio-inspired surfaces as a laminar flow control means

Relating the primitive hierarchy of the PREMO standard to the standard reference model for intelligent multimedia presentation systems

The need for a suitable classification of media types arises for several reasons when building or comparing multimedia systems. Within an Intelligent Multimedia Presentation Systems (IMMPS) it is necessary to formulate and encode design knowledge for decision making on the appropriate medium in which to present information and for the generation of the presentation. It is also required in order to specify interfaces to and between system components which will be employed to run a generated presentation before the user's eyes. This task is reflected in the SRM (Standard Reference Model, see this volume) for IMMPS by the Presentation Display Layer. However, the SRM does not instantiate this layer in detail, but instead refers to the PREMO ISO/IEC standard which provides a reference model for a presentation runtime environment for multimedia. PREMO already contains a set of basic structures, the so-called PREMO Primitive Hierarchy, to describe different media types. Thus the question arises, as to how far the PREMO Primitive Hierarchy could serve as a media classification for the SRM in general. In particular, this would support consistency between the design and presentation layers of the SRM if PREMO were used to instantiate the Presentation Layer. In the report, we first point to a number of typical problems with generating classifications of media types. We then provide a brief introduction to PREMO and its Primitive Hierarchy. Finally, the benefits and costs of using the PREMO primitive hierarchy for the SRM are discussed