Noncommutativity Approach to Supersymmetry on the Lattice: SUSY Quantum Mechanics and an Inconsistency

It is argued that the noncommutativity approach to fully supersymmetric field theories on the lattice suffers from an inconsistency. Supersymmetric quantum mechanics is worked out in this formalism and the inconsistency is shown both in general and explicitly for that system, as well as for the Abelian super BF model.Comment: 8 pages, typo's corrected, conclusions unchange

A Critique of the Link Approach to Exact Lattice Supersymmetry

We examine the link approach to constructing a lattice theory of N=2 super Yang Mills theory in two dimensions. The goal of this construction is to provide a discretization of the continuum theory which preserves all supersymmetries at non-zero lattice spacing. We show that this approach suffers from an inconsistency and argue that a maximum of just one of the supersymmetries can be implemented on the lattice.Comment: 7 page

Towards a framework for knowledge discovery: an architecture for distributed inductive databases

We discuss how data mining, patternbases and databases can be integrated into inductive databases, which make data mining an inductive query process. We propose a software architecture for such inductive databases, and extend this architecture to support the clustering of inductive databases and to make them suitable for data mining on the grid.Applications in Artificial Intelligence - Knowledge DiscoveryRed de Universidades con Carreras en Informática (RedUNCI

Single item inventory control under periodic review and a minimum order quantity

In this paper we study a periodic review single item single stage inventory system with stochastic demand. In each time period the system must order none or at least as much as a minimum order quantity Qmin. Since the optimal structure of an ordering policy with a minimum order quantity is complicated, we propose an easy-to-use policy, which we call (R, S,Qmin) policy. Assuming linear holding and backorder costs we determine the optimal numerical value of the level S using a Markov Chain approach. In addition, we derive simple news-vendor-type inequalities for near-optimal policy parameters, which can easily be implemented within spreadsheet applications. In a numerical study we compare our policy with others and test the performance of the approximation for three different demand distributions: Poisson, negative binomial, and a discretized version of the gamma distribution. Given the simplicity of the policy and its cost performance as well as the excellent performance of the approximation we advocate the application of the (R, S,Qmin) policy in practice

Exoplanet atmospheres with GIANO. I. Water in the transmission spectrum of HD 189733b

High-resolution spectroscopy (R $\ge$ 20,000) at near-infrared wavelengths can be used to investigate the composition, structure, and circulation patterns of exoplanet atmospheres. However, up to now it has been the exclusive dominion of the biggest telescope facilities on the ground, due to the large amount of photons necessary to measure a signal in high-dispersion spectra. Here we show that spectrographs with a novel design - in particular a large spectral range - can open exoplanet characterisation to smaller telescope facilities too. We aim to demonstrate the concept on a series of spectra of the exoplanet HD 189733 b taken at the Telescopio Nazionale Galileo with the near-infrared spectrograph GIANO during two transits of the planet. In contrast to absorption in the Earth's atmosphere (telluric absorption), the planet transmission spectrum shifts in radial velocity during transit due to the changing orbital motion of the planet. This allows us to remove the telluric spectrum while preserving the signal of the exoplanet. The latter is then extracted by cross-correlating the residual spectra with template models of the planet atmosphere computed through line-by-line radiative transfer calculations, and containing molecular absorption lines from water and methane. By combining the signal of many thousands of planet molecular lines, we confirm the presence of water vapour in the atmosphere of HD 189733 b at the 5.5-$\sigma$ level. This signal was measured only in the first of the two observing nights. By injecting and retrieving artificial signals, we show that the non-detection on the second night is likely due to an inferior quality of the data. The measured strength of the planet transmission spectrum is fully consistent with past CRIRES observations at the VLT, excluding a strong variability in the depth of molecular absorption lines.Comment: 10 pages, 8 figures. Accepted for publication in Astronomy & Astrophysics. v2 includes language editin

Detection of water absorption in the day side atmosphere of HD 189733 b using ground-based high-resolution spectroscopy at 3.2 microns

We report a 4.8 sigma detection of water absorption features in the day side spectrum of the hot Jupiter HD 189733 b. We used high-resolution (R~100,000) spectra taken at 3.2 microns with CRIRES on the VLT to trace the radial-velocity shift of the water features in the planet's day side atmosphere during 5 h of its 2.2 d orbit as it approached secondary eclipse. Despite considerable telluric contamination in this wavelength regime, we detect the signal within our uncertainties at the expected combination of systemic velocity (Vsys=-3 +5-6 km/s) and planet orbital velocity (Kp=154 +14-10 km/s), and determine a H2O line contrast ratio of (1.3+/-0.2)x10^-3 with respect to the stellar continuum. We find no evidence of significant absorption or emission from other carbon-bearing molecules, such as methane, although we do note a marginal increase in the significance of our detection to 5.1 sigma with the inclusion of carbon dioxide in our template spectrum. This result demonstrates that ground-based, high-resolution spectroscopy is suited to finding not just simple molecules like CO, but also to more complex molecules like H2O even in highly telluric contaminated regions of the Earth's transmission spectrum. It is a powerful tool that can be used for conducting an immediate census of the carbon- and oxygen-bearing molecules in the atmospheres of giant planets, and will potentially allow the formation and migration history of these planets to be constrained by the measurement of their atmospheric C/O ratios.Comment: 5 pages, 4 figures, accepted for publication in MNRAS Letter

A dynamic programming approach to multi-objective time-dependent capacitated single vehicle routing problems with time windows

A single vehicle performs several tours to serve a set of geographically dis- persed customers. The vehicle has a finite capacity and is only available for a limited amount of time. Moreover, tours' duration is restricted (e.g. due to quality or security issues). Because of road congestion, travel times are time-dependent: depending on the departure time at a customer, a different travel time is incurred. Furthermore, all customers need to get delivered in their specicified time windows. Contrary to most of the literature, we con- sider a multi-objective cost function: simultaneously minimizing the total time traveled including waiting times at customers due to time windows, and maximizing the total demand fulfilled. Efficient dynamic programming algorithms are developed to compute the Pareto set of routes, assuming a specific structure for time windows and travel time profiles

Titan's atmosphere as observed by Cassini/VIMS solar occultations: CH4_4, CO and evidence for C2_2H6_6 absorption

We present an analysis of the VIMS solar occultations dataset, which allows us to extract vertically resolved information on the characteristics of Titan's atmosphere between 100-700 km with a characteristic vertical resolution of 10 km. After a series of data treatment procedures, 4 occultations out of 10 are retained. This sample covers different seasons and latitudes of Titan. The transmittances show clearly the evolution of the haze and detect the detached layer at 310 km in Sept. 2011 at mid-northern latitudes. Through the inversion of the transmission spectra with a line-by-line radiative transfer code we retrieve the vertical distribution of CH$_4$ and CO mixing ratio. The two methane bands at 1.4 and 1.7 {\mu}m are always in good agreement and yield an average stratospheric abundance of $1.28\pm0.08$%. This is significantly less than the value of 1.48% obtained by the GCMS/Huygens instrument. The analysis of the residual spectra after the inversion shows that there are additional absorptions which affect a great part of the VIMS wavelength range. We attribute many of these additional bands to gaseous ethane, whose near-infrared spectrum is not well modeled yet. Ethane contributes significantly to the strong absorption between 3.2-3.5 {\mu}m that was previously attributed only to C-H stretching bands from aerosols. Ethane bands may affect the surface windows too, especially at 2.7 {\mu}m. Other residual bands are generated by stretching modes of C-H, C-C and C-N bonds. In addition to the C-H stretch from aliphatic hydrocarbons at 3.4 {\mu}m, we detect a strong and narrow absorption at 3.28 {\mu}m which we tentatively attribute to the presence of PAHs in the stratosphere. C-C and C-N stretching bands are possibly present between 4.3-4.5 {\mu}m. Finally, we obtain the CO mixing ratio between 70-170 km. The average result of $46\pm16$ ppm is in good agreement with previous studies.Comment: 51 pages, 28 figure