Defining Original Presentism

It is surprisingly hard to define presentism. Traditional definitions of the view, in terms of tensed existence statements, have turned out not to to be capable of convincingly distinguishing presentism from eternalism. Picking up on a recent proposal by Tallant, I suggest that we need to locate the break between eternalism and presentism on a much more fundamental level. The problem is that presentists have tried to express their view within a framework that is inherently eternalist. I call that framework the Fregean nexus, as it is defined by Frege’s atemporal understanding of predication. In particular, I show that the tense-logical understanding of tense which is treated as common ground in the debate rests on this very same Fregean nexus, and is thus inadequate for a proper definition of presentism. I contrast the Fregean nexus with what I call the original temporal nexus, which is based on an alternative, inherently temporal form of predication. Finally, I propose to define presentism in terms of the original temporal nexus, yielding original presentism. According to original presentism, temporal propositions are distinguished from atemporal ones not by aspects of their content, as they are on views based on the Fregean nexus, but by their form—in particular, by their form of predication

Cubatic phase for tetrapods

We investigate the phase behavior of tetrapods, hard non-convex bodies formed by 4 rods connected under tetrahedral angles. We predict that, depending on the relative lengths of the rods these particles can form a uniaxial nematic phase, and more surprisingly they can exhibit a cubatic phase, a special case of the biaxial nematic phase. These predictions may be experimentally testable, as experimental realizations of tetrapods have recently become available.Comment: 8 pages ReVTeX 4, including 3 EPS figure

Improved procedure for determining the ductility of buildings under seismic loads

Displacement ductility is a parameter that characterizes the seismic response of structures. Moreover, displacement ductility can be used in order to determine whether a structural design, performed according to a specific seismic code or not, may achieve the main goal of the seismic design: to develop energy dissipation in a stable manner. Determination of displacement ductility is not an easy task, because the structural response usually does not show a clear location of the points that define yield and ultimate displacements. In this paper, some of the main procedures for ductility displacement are revised and compared, and then improvements are performed to such procedures in order to compute the displacement ductility. A new procedure is then introduced, leading to determine the ultimate displacement using the seismic collapse threshold and the yield displacement, achieving the balance of dissipated energy. The procedure has been used to calculate displacement ductility of reinforced concrete framed buildings.Peer Reviewe

Do cylinders exhibit a cubatic phase?

We investigate the possibility that freely rotating cylinders with an aspect ratio $L/D=0.9$ exhibit a cubatic phase similar to the one found for a system of cut-spheres. We present theoretical arguments why a cubatic phase might occur in this particular system. Monte Carlo simulations do not confirm the existence of a cubatic phase for cylinders. However, they do reveal an unexpected phase behavior between the isotropic and crystalline phase.Comment: 24 pages, 12 figures, RevTex (Submitted to J. Chem. Phys.

The Belgian labour market during and after the crisis

The article looks at the impact that the 2008-2009 recession had on the Belgian labour market and, whilst taking account of the varying severity and duration of the economic downturn, draws a comparison with other European countries. More specifically, the consequences are investigated with regard to the adaptation of volume of labour and labour costs, and also the composition of employment. The analysis for Belgium shows that the crisis was accompanied by a less than proportional contraction in the volume of labour, resulting in a fall in labour productivity. The reduction in the volume of labour was only partly reflected in the trend in employment as the use of measures aimed at limiting working time, with a considerable fall in the number of hours worked per employee as a result, was accompanied by considerable labour hoarding. In general terms, the crisis did not result in a fall in the activity rate, but there is a major risk of discouragement among low-skilled young people. The increase in long-term unemployment points in turn to the threat of a rise in structural unemployment, which may adversely affect the potential for growth in the economy. The crisis did not have a moderating effect on the trend in hourly labour costs. After allowing for the productivity trend, the labour cost handicap, expressed in unit labour costs, narrowed temporarily with respect to the three neighbouring countries, but an increase in this handicap was once again posted in 2010.labour hoarding, long-term unemployment, labour productivity, labour cost handicap, hysteresis