Econometric Modeling and Analysis of Residential Water Demand Based on Unbalanced Panel Data

This paper develops an econometric methodology devised to analyze a sample of time unbalanced panel data on residential water consumption in the French island La Reunion with the purpose to bring out the main determinants of household water consumption and estimate the importance of water consumption by uses. For this purpose, we specify a daily panel econometric model and derive, by performing a time aggregation, a general linear regression model accounting for water consumption data recorded on periods of any calendar date and time length. To esti-mate efficiently the parameters of this model we develop a feasible two step generalized least square method. Using the principle of best linear unbiased prediction, we finally develop an approach allowing to consistently break down the volume of water consumption recorded on household water bills by uses, namely by enforcing this estimated decomposition to add up to the observed total. The application of this methodology to a sample of 437 unbalanced panel observations shows the scope of this approach for the empirical analysis of actual data.econometric modeling; water consumption; panel data

Sudden To Adiabatic Transition in Beta Decay

We discuss effects in beta decays at very low beta energies, of the order of the kinetic energies of atomic electrons. As the beta energy is lowered the atomic response changes from sudden to adiabatic. As a consequence, the beta decay rate increases slightly and the ejection of atomic electrons (shake off) and subsequent production of X rays is turned off. We estimate the transition energy and the change in decay rate. The rate increase is largest in heavy atoms, which have a small Q value in their decay. The X ray switch-off is independent of Q value.Comment: 6 pages LaTe

QSO hosts and environments at z=0.9 to 4.2: JHK images with adaptive optics

We have observed nine QSOs with redshifts 0.85 to 4.16 at near-IR wavelengths with the adaptive optics bonnette of the Canada-France-Hawaii telescope. Exposure times ranged from 1500 to 24000s (mostly near 7000s) in J, H, or K bands, with pixels 0.035 arcsec on the sky. The FWHM of the co-added images at the location of the quasars are typically 0.16 arcsec. Including another QSO published previously, we find associated QSO structure in at least eight of ten objects, including the QSO at z = 4.16. The structures seen in all cases include long faint features which appear to be tidal tails. In four cases we have also resolved the QSO host galaxy, but find them to be smooth and symmetrical: future PSF removal may expand this result. Including one object previously reported, of the nine objects with more extended structure, five are radio-loud, and all but one of these appear to be in a dense small group of compact galaxy companions. The radio-quiet objects do not occupy the same dense environments, as seen in the NIR. In this small sample we do not find any apparent trends of these properties with redshift, over the range 0.8 < z < 2.4. The colors of the host galaxies and companions are consistent with young stellar populations at the QSO redshift. Our observations suggest that adaptive optic observations in the visible region will exhibit luminous signatures of the substantial star-formation activity that must be occurring.Comment: 22 pages including 10 tables, plus 11 figures. To appear in A

Effective field theory and the quark model

We analyze the connections between the quark model (QM) and the description of hadrons in the low-momentum limit of heavy-baryon effective field theory in QCD. By using a three-flavor-index representation for the effective baryon fields, we show that the ``nonrelativistic'' constituent QM for baryon masses and moments is completely equivalent through O(m_s) to a parametrization of the relativistic field theory in a general spin--flavor basis. The flavor and spin variables can be identified with those of effective valence quarks. Conversely, the spin-flavor description clarifies the structure and dynamical interpretation of the chiral expansion in effective field theory, and provides a direct connection between the field theory and the semirelativistic models for hadrons used in successful dynamical calculations. This allows dynamical information to be incorporated directly into the chiral expansion. We find, for example, that the striking success of the additive QM for baryon magnetic moments is a consequence of the relative smallness of the non-additive spin-dependent corrections.Comment: 25 pages, revtex, no figure

Low efficacy of the combination artesunate plus amodiaquine for uncomplicated falciparum malaria among children under 5 years in Kailahun, Sierra Leone.

OBJECTIVE: In 2004, Sierra Leone adopted artesunate plus amodiaquine as first-line antimalarial treatment. We evaluated the efficacy of this combination in Kailahun, where a previous study had shown 70.2% efficacy of amodiaquine in monotherapy. METHODS: Method and outcome classification of the study complied with WHO guidelines. Children 6-59 months with uncomplicated malaria were followed-up for 28 days. PCR genotyping was used to distinguish recrudescence from reinfection. Reinfections were reclassified as cured. RESULTS: Of 172 children who were referred to the study clinic, 126 satisfied inclusion criteria and were enrolled. No early treatment failures were reported. The day 14, efficacy was 98.2% (95% CI: 93.8-99.8). Of 65 recurrent parasitaemias analysed by PCR, 17 were recrudescences. The PCR-adjusted day 28 efficacy was 84.5% (95% CI: 76.4-90.7). All true failures occurred in the last 8 days of follow-up. Of 110 children who completed the 28-day follow-up, 54 (49.1%) experienced a novel infection. CONCLUSION: The efficacy of this combination was disappointing. The high reinfection rate suggested little prophylactic effect. In Kailahun a more efficacious combination might be necessary in the future. The efficacy of AS + AQ needs to be monitored in Kailahun and in the other regions of Sierra Leone

A Population of Compact Elliptical Galaxies Detected with the Virtual Observatory

Compact elliptical galaxies are characterized by small sizes and high stellar densities. They are thought to form through tidal stripping of massive progenitors. However, only a handful of them were known, preventing us from understanding the role played by this mechanism in galaxy evolution. We present a population of 21 compact elliptical galaxies gathered with the Virtual Observatory. Follow-up spectroscopy and data mining, using high-resolution images and large databases, show that all the galaxies exhibit old metal-rich stellar populations different from those of dwarf elliptical galaxies of similar masses but similar to those of more massive early-type galaxies, supporting the tidal stripping scenario. Their internal properties are reproduced by numerical simulations, which result in compact dynamically hot remnants resembling the galaxies in our sample.Comment: 26 pages, 5 figures, 2 tables. Science in press, published in Science Express on 1/Oct/2009. Full resolution figures in the supplementary online material are available from the Science Magazine web-sit

The charmonium and bottomonium mass spectroscopy with a simple approximaton of the kinetic term

In this paper we propose a particular description of meson spectroscopy, with emphasis in heavy bound states like charmonia and bottomonia, after working on the main aspects of the construction of an effective potential model. We use the prerogatives from ``soft QCD'' to determine the effective potential terms, establishing the asymptotic Coulomb term from one gluon exchange approximation. At the same time, a linear confinement term is introduced in agreement with QCD and phenomenological prescription. The main aspect of this work is the simplification in the calculation, consequence of a precise and simplified description of the kinetic term of the Hamiltonian. With this proposition we perform the calculations of mass spectroscopy for charmonium and bottomonium mesons and we discuss the real physical possibilities of developing a generalized potential model, its possible advantages relative to experimental parameterization and complexity in numerical calculations

New electron source concept for single-shot sub-100 fs electron diffraction in the 100 keV range

We present a method for producing sub-100 fs electron bunches that are suitable for single-shot ultrafast electron diffraction experiments in the 100 keV energy range. A combination of analytical results and state-of-the-art numerical simulations show that it is possible to create 100 keV, 0.1 pC, 20 fs electron bunches with a spotsize smaller than 500 micron and a transverse coherence length of 3 nm, using established technologies in a table-top set-up. The system operates in the space-charge dominated regime to produce energy-correlated bunches that are recompressed by established radio-frequency techniques. With this approach we overcome the Coulomb expansion of the bunch, providing an entirely new ultrafast electron diffraction source concept

The Scattering Approach to the Casimir Force

We present the scattering approach which is nowadays the best tool for describing the Casimir force in realistic experimental configurations. After reminders on the simple geometries of 1d space and specular scatterers in 3d space, we discuss the case of stationary arbitrarily shaped mirrors in electromagnetic vacuum. We then review specific calculations based on the scattering approach, dealing for example with the forces or torques between nanostructured surfaces and with the force between a plane and a sphere. In these various cases, we account for the material dependence of the forces, and show that the geometry dependence goes beyond the trivial {\it Proximity Force Approximation} often used for discussing experiments.Comment: Proceedings of the QFEXT'09 conference (Oklahoma, 2009