Logarithmic good reduction, monodromy and the rational volume

Let $R$ be a strictly local ring complete for a discrete valuation, with fraction field $K$ and residue field of characteristic $p > 0$. Let $X$ be a smooth, proper variety over $K$. Nicaise conjectured that the rational volume of $X$ is equal to the trace of the tame monodromy operator on $\ell$-adic cohomology if $X$ is cohomologically tame. He proved this equality if $X$ is a curve. We study his conjecture from the point of view of logarithmic geometry, and prove it for a class of varieties in any dimension: those having logarithmic good reduction.Comment: final version, to appear in Algebra & Number Theor

The relation between movement parameters and motor learning.

In a recent paper, Flament et al (1999) studied the learning to flex the elbow fast. They concluded from their data that time-related parameters (e.g. movement time) changed faster during learning than magnitude-related parameters (e.g. peak velocity), and discussed this finding in terms of neural substrates responsible for the apparently different learning mechanisms. In this note, I will argue that finding different time constants does not imply different learning mechanisms. I will give a theoretical example of the development of parameters during learning to move faster. Despite the fact that I model only one learning process, various kinematic parameters show different time courses of learning. The differences the model predicts are comparable with the experimental results

Are There Fast Tracks in Economic Departments? Evidence from a Sample of Top Economists

In this paper, we analyze the timing of promotions in academic departments. Contrary to previous attempts in the empirical literature, we test alternative theories of fast tracks by adding a measure of performance in our analysis. We find that learning from past performance is an important factor to explain the time spent as assistant and associate professor. In addition, our analysis shows the existence of a handicapping policy: individuals who had a fast promotion in the past are less likely to be promoted quickly again. We also find that the handicap is relative, that it does not survive the whole career and that it is possible for these individuals to beat it if they achieve a given level of productivity. We interpret our find- ings as evidence that incentives and sorting matter in academia and that using relative handicaps can help to balance these two concerns. Finally, we look at the productivity pattern of individuals with different career profiles and find that fast tracks are always more productive than their pairs, even after the last promotion, what suggests an effective selection process.Fast track; Incentives; Sorting; Productivity; Economic departments

Finding simultaneous Diophantine approximations with prescribed quality

We give an algorithm that finds a sequence of approximations with Dirichlet coefficients bounded by a constant only depending on the dimension. The algorithm uses the LLL-algorithm for lattice basis reduction. We present a version of the algorithm that runs in polynomial time of the input.Comment: 16 pages, 7 figure

Multiple Specification of an Object’s Size for Picking it up.

Subjects were asked to pick up disks. The apparent size of the disks was manipulated by a visual illusion. Of the two aspects of the action which depend on the objects size, only one was affected by the illusion. We conclude that different aspects of an action are controlled independently, instead of being co-ordinated on the basis of one perceptual variable

A new view on grasping

Reaching out for an object is often described as consisting of two components that are based on different visual information. Information about the object’s position and orientation guides the hand to the object, while information about the object’s shape and size determines how the fingers move relative to the thumb to grasp it. We propose an alternative description, which consists of determining suitable positions on the object — on the basis of its shape, surface roughness, and so on — and then moving one’s thumb and fingers more or less independently to these positions. We modelled this description using a minimum jerk approach, whereby the finger and thumb approach their respective target positions approximately orthogonally to the surface. Our model predicts how experimental variables such as object size, movement speed, fragility, and required accuracy will influence the timing and size of the maximum aperture of the hand. An extensive review of experimental studies on grasping showed that the predicted influences correspond to human behaviour

Job Creation, Job Destruction and Voting Behavior in Poland

This paper analyzes the effect of job creation and job destruction on the voting patterns of individuals in Poland during the 1997 and 2001 parliamentary elections. First, we link the votes for the left wing party to the unemployment rate and the job creation and destruction rates in the constituency. We show that the job destruction rate and unemployment rate has a positive effect on the votes for the SLD, while the job creation rate has a negative effect. Second, we look at the effect of the change in job creation and job destruction rates on the change in the votes for individual candidates. We find that incumbents from the former right wing coalition received less votes if excess job reallocation had increased in their constituency. Therefore, the paper provides evidence that job flows have a strong impact on voting patterns and that the balance between the positive and negative effects of reforms determine to a large extent the political outcome.Job creation; Job destruction; voting behavior; gradualism

Dual exposure interferometry

The application of dual exposure differential interferometry to gas dynamics and flow visualization is discussed. A differential interferometer with Wallaston prisms can produce two complementary interference fringe systems, depending on the polarization of the incident light. If these two systems are superimposed on a film, with one exposure during a phenomenon, the other before or after, the phenomenon will appear on a uniform background. By regulating the interferometer to infinite fringe distance, a resolution limit of approximately lambda/500 can be obtained in the quantitative analysis of weak phase objects. This method was successfully applied to gas dynamic investigations