Modules with irrational slope over tubular algebras

Let $A$ be a tubular algebra and let $r$ be a positive irrational. Let ${\mathcal D}_r$ be the definable subcategory of $A$-modules of slope $r$. Then the width of the lattice of pp formulas for ${\mathcal D}_r$ is $\infty$. It follows that if $A$ is countable then there is a superdecomposable pure-injective module of slope $r$.Comment: minor corrections/improvements to argument

Predictive Liability Models and Visualizations of High Dimensional Retail Employee Data

Employee theft and dishonesty is a major contributor to loss in the retail industry. Retailers have reported the need for more automated analytic tools to assess the liability of their employees. In this work, we train and optimize several machine learning models for regression prediction and analysis on this data, which will help retailers identify and manage risky employees. Since the data we use is very high dimensional, we use feature selection techniques to identify the most contributing factors to an employee's assessed risk. We also use dimension reduction and data embedding techniques to present this dataset in a easy to interpret format

Is upstate New York showing signs of a turnaround?

Upstate New York may have shown signs of a turnaround in 1997 and 1998, but its economic performance is still well below that of the nation and New York State as a whole.Federal Reserve District, 2nd ; New York (State) ; Economic conditions - United States

Thermal diffusivity and chaos in metals without quasiparticles

We study the thermal diffusivity $D_T$ in models of metals without quasiparticle excitations (`strange metals'). The many-body quantum chaos and transport properties of such metals can be efficiently described by a holographic representation in a gravitational theory in an emergent curved spacetime with an additional spatial dimension. We find that at generic infra-red fixed points $D_T$ is always related to parameters characterizing many-body quantum chaos: the butterfly velocity $v_B$, and Lyapunov time $\tau_L$ through $D_T \sim v_B^2 \tau_L$. The relationship holds independently of the charge density, periodic potential strength or magnetic field at the fixed point. The generality of this result follows from the observation that the thermal conductivity of strange metals depends only on the metric near the horizon of a black hole in the emergent spacetime, and is otherwise insensitive to the profile of any matter fields.Comment: 27 page

Job changes, hours changes and the path of labour supply adjustment

This paper uses the first twelve waves of the British Household Panel Survey covering the period 1991-2002 to investigate single women's labour supply changes in response to three tax and benefit policy reforms that occurred in the 1990s. We find evidence of small labour supply effects for two of such reforms. A third reform in 1999 instead led to a significant increase in single mothers' hours of work. This increase was primarily driven by women who changed job, suggesting that labour supply adjustments within a job are harder than across jobs. The presence of hours inflexibility within jobs and labour supply adjustments through job mobility are strongly confirmed when we look at hours changes by stated labour supply preferences. Finally, we find little overall effect on wages.Job mobility; Hours flexibility; Labour supply preferences; Hours-wage trade-off; Monopsony

Supernovae Types Ia/II and Intracluster Medium Enrichment

We re-examine the respective roles played by supernovae (SNe) Types Ia and II in enriching the intracluster medium (ICM) of galaxy clusters, in light of the recent downward shift of the ASCA abundance ratios of alpha-elements to iron favoured by Ishimaru & Arimoto (1997, PASJ, 49, 1). Because of this shift, Ishimaru & Arimoto conclude that >50% of the ICM iron must have originated from within Type Ia SNe progenitors. A point not appreciated in their study, nor in most previous analyses, is the crucial dependence of such a conclusion upon the adopted massive star physics. Employing several alternative Type II SN yield compilations, we demonstrate how uncertainties in the treatment of convection and mass-loss can radically alter our perception of the relative importance of Type Ia and II SNe as ICM polluters. If mass-loss of the form favoured by Maeder (1992, A&A, 264, 105) or convection of the form favoured by Arnett (1996, Supernovae and Nucleosynthesis) is assumed, the effect upon the oxygen yields would lead us to conclude that Type Ia SNe play no part in polluting the ICM, in contradiction with Ishimaru & Arimoto. Apparent dichotomies still exist (e.g. the mean ICM neon-to-iron ratio implies a 100% Type II Fe origin, while the mean sulphur ratio indicates a 100% Type Ia origin) that cannot be reconciled with the currently available yield tables.Comment: 6 pages (incl 1 PostScript figure), LaTeX, also available at http://msowww.anu.edu.au/~gibson/publications.html, MNRAS, in pres

Job changes, hours changes and labour market flexibility: panel data evidence for Britain

This study uses the first twelve waves of the British Household Panel Survey covering the period 1991-2002 to investigate the extent of constraints on desired hours of work within jobs and the degree of flexibility of the labour market for a sample of women. Our main findings are as follows. First, the largest movements in hours worked are observed for workers who change their jobs. Second, about 40 percent of the women in the sample are not putting in the hours they would like. Most of them (mainly full-timers) would like to work fewer hours at the prevailing hourly wage. Again, women who change job experience the greatest hours changes, especially if they are over- or under-employed. Third, there is evidence of hours constraints. The hours movements among quitters are up to 5 hours greater than the movements among stayers. Fourth, we do not detect systematic time trends in the relationship between hours changes and job changes. But there is some evidence that overemployed women find it increasingly more difficult to move towards their desired hours even after changing job. Fifth, the evidence on a flexible labour market is mixed. We find only partial support for the hypothesis that overemployed or underemployed quitters receive compensating wage differentials if the new job does not satisfy their hours preferences, as well as for the hypothesis that quitters get a wage premium when they end up moving to jobs that constraint their desired hours.Job mobility; Hours constraints; Labour supply preferences; Hours-wage trade-off; Part-time employment.