Growth of heat trace and heat content asymptotic coefficients

We show in the smooth category that the heat trace asymptotics and the heat content asymptotics can be made to grow arbitrarily rapidly. In the real analytic context, however, this is not true and we establish universal bounds on their growth

A Simultaneous Optical and X-ray Variability Study of the Orion Nebula Cluster. II. A Common Origin in Magnetic Activity

We present a statistical analysis of simultaneous optical and X-ray light curves, spanning 600 ks, for 814 pre-main-sequence (PMS) stars in the Orion Nebula Cluster. The aim of this study is to establish the relationship, if any, between the sites of optical and X-ray variability, and thereby to elucidate the origins of X-ray production in PMS stars. In a previous paper we showed that optical and X-ray variability in PMS stars are very rarely time-correlated. Here, using time-averaged variability indicators to examine the joint occurrences of optical and X-ray variability, we confirm that the two forms of variability are not directly causally related. However, a strong and highly statistically significant correlation is found between optical variability and X-ray luminosity. As this correlation is found to be independent of accretion activity, we argue that X-ray production in PMS stars must instead be intimately connected with the presence and strength of optically variable, magnetically active surface regions (i.e. spots) on these stars. Moreover, because X-ray variability and optical variability are rarely time-correlated, we conclude that the sites of X-ray production are not exclusively co-spatial with these regions. We argue that solar-analog coronae, heated by topologically complex fields, can explain these findings.Comment: To appear in the Astrophysical Journal. 33 pages, 3 figure

Thruster Allocation for Dynamical Positioning

Positioning a vessel at a fixed position in deep water is of great importance when working offshore. In recent years a Dynamical Positioning (DP) system was developed at Marin [2]. After the measurement of the current position and external forces (like waves, wind etc.), each thruster of the vessel is actively controlled to hold the desired location. In this paper we focus on the allocation process to determine the settings for each thruster that results in the minimal total power and thus fuel consumption. The mathematical formulation of this situation leads to a nonlinear optimization problem with equality and inequality constraints, which can be solved by applying Lagrange multipliers. We give three approaches: first of all, the full problem was solved using the MATLAB fmincon routine with the solution from the linearised problem as a starting point. This implementation, with robust handling of the situations where the thrusters are overloaded, lead to promising results: an average reduction in fuel consumption of approximately two percent. However, further analysis proved useful. A second approach changes the set of variables and so reduces the number of equations. The third and last approach solves the Lagrange equations with an iterative method on the linearized Lagrange problem

Old Belief and the Balance of Red and Blue: How Old Believers Managed Cultural Infringement

This paper covers the spread of the Old Believers into Western society, studying how they changed and evolved during the Cold War. The paper focuses on two communities, using them to compare the different attitudes Old Believers had towards differing host cultures. Using a litany of newspapers and the work of a few dedicated anthropologists, Old Belief and the Balance of Red and Blue: How Old Believers Managed Cultural Infringement shows the vast array of responses to a small group of Russian sectarians establishing themselves within Western Cultures of differing size and values

Discovery of the near-infrared counterpart to the luminous neutron-star low-mass X-ray binary GX 3+1

Using the High Resolution Camera onboard the Chandra X-ray Observatory, we have measured an accurate position for the bright persistent neutron-star X-ray binary and atoll source GX 3+1. At a location that is consistent with this new position we have discovered the near-infrared (NIR) counterpart to GX 3+1 in images taken with the PANIC and FourStar cameras on the Magellan Baade Telescope. The identification of this K_s=15.8+-0.1 mag star as the counterpart is based on the presence of a Br-gamma emission line in a NIR spectrum taken with the FIRE spectrograph on the Baade Telescope. The absolute magnitude derived from the best available distance estimate to GX 3+1 indicates that the mass donor in the system is not a late-type giant. We find that the NIR light in GX 3+1 is likely dominated by the contribution from a heated outer accretion disk. This is similar to what has been found for the NIR flux from the brighter class of Z sources, but unlike the behavior of atolls fainter (Lx ~ 1e36 to 1e37 erg/s) than GX 3+1, where optically-thin synchrotron emission from a jet probably dominates the NIR flux.Comment: Accepted for publication in Ap

The use of willingness to pay experiments : estimating demand for piped water connections in Sri Lanka

The authors show how willingness to pay surveys can be used to gauge household demand for improved network water and sanitation services. They do this by presenting a case-study from Sri Lanka, where they surveyed approximately 1,800 households in 2003. Using multivariate regression, they show that a complex combination of factors drives demand for service improvements. While poverty and costs are found to be key determinants of demand, the authors also find that location, self-provision, and perceptions matter as well, and that subsets of these factors matter differently for subsamples of the population. To evaluate the policy implications of the demand analysis, they use the model to estimate uptake rates of improved service under various scenarios-demand in subgroups, the institutional decision to rely on private sector provision, and various financial incentives targeted to the poor. The simulations show that in this particular environment in Sri Lanka, demand for piped water services is low, and that it is unlikely that under the present circumstances the goal of nearly universal piped water coverage is going to be achieved. Policy instruments, such as subsidization of connection fees, could be used to increase demand for piped water, but it is unclear whether the benefits of the use of such policies would outweigh the costs.Town Water Supply and Sanitation,Environmental Economics&Policies,Water Use,Small Area Estimation Poverty Mapping,Urban Water Supply and Sanitation

De groeiende groep jongvolwassen thuiswonenden:Kenmerken van blijvers en terugkeerders tussen 2011 en 2021

In dit artikel staat de trend in thuis wonen, uit huis gaan en terugkeren naar het ouderlijk huis onder 18- tot 31-jarigen in de periode 2011 tot 2021 centraal. De focus hierbij ligt op de samenstelling van de verschillende groepen: welke kenmerken hebben jongvolwassenen die uit huis gaan of die juist nog bij hun ouders wonen? Tussen 2011 en 2021 steeg het percentage thuiswonende 18- tot 31-jarigen van 50 naar 55 procent onder mannen en van 37 tot 44 procent onder vrouwen. Er was een stijging onder alle leeftijden en onder zowel studenten als werkenden. Thuiswonenden zijn steeds vaker werkenden, 20 procent heeft een vast contract. Het percentage jongvolwassenen dat terug naar huis gaat, is juist gedaald. Dit kan grotendeels verklaard worden doordat jongeren op latere leeftijd uit huis gaan en vaker al werken