Further econometric evidence on the extent and sources of cost savings in competitively tendered contracts

By estimating a flexible nonlinear regression model of savings on an original dataset of service procurements conducted by the Spanish Armed Forces, this paper provides robust and precise novel econometric evidence on the extent and sources of cost savings in public procurement. The net effect on savings of the policy-amenable and economically advantageous variables that we estimate, such as the size of the procured function, the importance of price in the contract award criteria, and the number of bidders who participate in the tendering, may help contracting agencies to select management practices and to forecast the price paid out. We find that savings increase proportionally to the size of the procured function, that an increase of 10 percentage points in the importance of price increases savings by approximately 2% of the function’s size, and that savings are generally reduced by restricting the number of bidders. A comparison with estimates reported in previous studies is also made

Desempeño de los sistemas de vigilancia de salud pública durante la pandemia de influenza A (H1N1) en las Américas: prueba de un nuevo método basado en la Ley de Benford

The A(H1N1) influenza pandemic has been a challenge for public health surveillance systems in all countries. An objective evaluation has not been conducted, as yet, of the performance of those systems during the pandemic. This paper presents an algorithm based on Benford’s Law and the mortality ratio in order to evaluate the quality of the data and the sensitivity of surveillance systems. It analyses records of confirmed cases reported to the Pan American Health Organization by its 35 member countries between epidemiological weeks 13 and 47 in 2009. Seventeen countries did not fulfil Benford’s Law, and mortality exceeded the regional average in 40% of the countries. The results suggest uneven performance by surveillance systems in the different countries, with the most frequent problem being low diagnostic coverage. Benford’s Law proved to be a useful tool for the evaluation of a public health surveillance system’s performance

Study of the effects of thermally thin and thermally thick particle approaches on the Eulerian modeling of a biomass combustor operating with wood chips

Two particle treatments, thermally thin and thick, are applied to Eulerian combustion modeling for biomass packed beds and tested through the simulation of an experimental plant. The paper shows the efficiency of the Eulerian approach for large packed beds and tests the behavior of both particle treatments, tested with in-bed and flame temperatures and released volatiles measurements at different locations, which is not common in the literature for a full size boiler. Both approaches are implemented in a model with a comprehensive framework that includes several submodels for the thermal conversion kinetics, bed motion, heat and mass transfer with the gas phase, and gas flow and reaction. Two experiments are performed with wood chips fuels with different moisture contents. The simulations of the two cases result in reasonably good predictions for both particle treatments. The results are similar for higher moisture content and, for the low-moisture test, the bed temperature distribution and reaction fronts are slightly different due to the different predictions of the drying and devolatilization fronts. The volatile measurements show that the T. Thin model results in slightly more accurate predictions than the T. Thick, possibly because the wood chips have a more thermally thin behaviorMinisterio de Ciencia, Innovación y Universidades | Ref. PID2021-126569OB-I00Universidade de Vigo/CISU

Barrios en transición

El proyecto de investigación acción participativa Barrios en Transición se enmarca en el Movimiento de transición, con origen en el Reino Unido [1], que viene generando a nivel mundial un creciente número de iniciativas ciudadanas e institucionales, articuladas en red y vinculadas a la idea de comunidades, ciudades, pueblos, barrios o bosques en transición hacia un modelo de civilización post-carbono. Esta corriente de pensamiento, que ha confluido con el movimiento del decrecimiento [2] [3], con origen en Francia, plantea un "mapa de ruta" para un futuro sostenible de la ciudad a través de una serie de adaptaciones en los ámbitos de la producción y gestión de la energía, el agua, la salud, la educación, la economía y la agricultura dirigidas a incrementar la autonomía, reducir las emisiones de CO2 e incrementar la resiliencia a los cambios de la comunidades. Estas iniciativas, que se mueven de abajo a arriba, están llamadas a encontrarse con las iniciativas que, partiendo desde el marco institucional, desde arriba hacia abajo, plantean las bases de un nuevo urbanismo sostenible y participativo con un enfoque integrado del desarrollo urbano. (Carta de Aalborg de 1994, Carta de Leipzig de 2007, Red de ciudades sostenibles). Planteamos como hipótesis que es necesaria y posible la confluencia de ambos movimientos sobre la base de una nueva generación de políticas urbanas y de revitalización de barrios basada en la cogestión entre la iniciativa social y la administración pública. Para ello la investigación plantea como metodología el estudio de casos y la puesta en marcha de una experiencia piloto de cogestión de barrios en transición en Alcosa (Sevilla) y otra en Casería de Montijo (Granada). El proyecto plantea la interacción entre siete ejes de actuación: Vivienda, Espacio público, Accesibilidad y Movilidad, Soberanía alimentaria, Soberanía financiera y económica del bien común, agua, energía y economía local, soberanía energética y mejora ambiental y educación socioambiental. Nos proponemos investigar sobre la capacidad de acciones de pequeña escala y alcance inmediato, interrelacionadas, para generar procesos de círculos virtuosos que permitan avanzar hacia barrios más habitables, más cohesionados, más vivos, más participativos, con comunidades más fuertes que emprendan medidas para mejorar sus barrios reduciendo su huella de carbono al tiempo que desarrollan la economía de barrio y fortalecen la comunidad

Modeling the Odor Generation in WWTP: An Integrated Approach Review

International audienceNuisance odors generation from waste and wastewater treatment plants are a cause of public discomfort and complaints. This situation impairs the air quality and represents a growing social and public health problem, especially in developing countries. Several modeling approaches have been developed and successfully implemented in the frame of a wastewater treatment plant for both the biological treatment and physicochemical processes. The mathematical modeling of the odor generation process is still considered a quite complex issue, mainly due to the fact that olfactory nuisance can be caused by many different chemical compounds and the perception of odors is influenced by subjective thresholds. Moreover, the impact of odor sources on air quality is highly conditioned by complex atmospheric dispersion processes. This review presents a critical state-of-art and assessment where information related to odor emissions impact studies as well as modeling applications are compiled and discussed

Automatic linguistic reporting of customer activity patterns in open malls

In this work, we present a complete system to produce an automatic linguistic reporting about the customer activity patterns inside open malls, a mixed distribution of classical malls joined with the shops on the street. These reports can assist to design marketing campaigns by means of identifying the best places to catch the attention of customers. Activity patterns are estimated with process mining techniques and the key information of localization. Localization is obtained with a parallelized solution based on WiFi fingerprint system to speed up the solution. In agreement with the best practices for human evaluation of natural language generation systems, the linguistic quality of the generated report was evaluated by 41 experts who filled in an online questionnaire. Results are encouraging, since the average global score of the linguistic quality dimension is 6.17 (0.76 of standard deviation) in a 7-point Likert scale. This expresses a high degree of satisfaction of the generated reports and validates the adequacy of automatic natural language textual reports as a complementary tool to process model visualization. © 2021, The Author(s)

Surface Structure of Liquid Metals and the Effect of Capillary Waves: X-ray Studies on Liquid Indium

We report x-ray reflectivity (XR) and small angle off-specular diffuse scattering (DS) measurements from the surface of liquid Indium close to its melting point of $156^\circ$C. From the XR measurements we extract the surface structure factor convolved with fluctuations in the height of the liquid surface. We present a model to describe DS that takes into account the surface structure factor, thermally excited capillary waves and the experimental resolution. The experimentally determined DS follows this model with no adjustable parameters, allowing the surface structure factor to be deconvolved from the thermally excited height fluctuations. The resulting local electron density profile displays exponentially decaying surface induced layering similar to that previously reported for Ga and Hg. We compare the details of the local electron density profiles of liquid In, which is a nearly free electron metal, and liquid Ga, which is considerably more covalent and shows directional bonding in the melt. The oscillatory density profiles have comparable amplitudes in both metals, but surface layering decays over a length scale of $3.5\pm 0.6$ \AA for In and $5.5\pm 0.4$ \AA for Ga. Upon controlled exposure to oxygen, no oxide monolayer is formed on the liquid In surface, unlike the passivating film formed on liquid Gallium.Comment: 9 pages, 5 figures; submitted to Phys. Rev.

Determinación de la contaminación acústica en el entorno del Aeropuerto Internacional de Ezeiza

A través del presente trabajo se buscó obtener una noción preliminar de la situación actual del aeropuerto en lo referente a contaminación acústica. Este estudio se enfocó en el marco de los Green airports (aeropuertos verdes), iniciativa llevada a cabo por las principales autoridades del ámbito aeronáutico para el desarrollo de aeropuertos ecológicamente sustentables. Dichos análisis fueron realizados mediante software especializado, tales como el INM 7.0 (Integrated Noise Model de la FAA) y el Custic 3.2. La Metodología consistió en plantear distintos escenarios operativos del aeropuerto, para luego simularlos. Con esta información se pudieron construir las respectivas huellas de ruido. Este documento se centra sobre tres pilares fundamentales que hacen a la actividad de los aeropuertos; las operaciones de los vehículos de asistencia a las aeronaves o GSE (Ground Support Equipment) que circulan por la plataforma comercial, las operaciones de rodaje de las aeronaves (Taxing) y las operaciones de aproximación y despegue.Facultad de Ingenierí

Surface tension of the most popular models of water by using the test-area simulation method

We consider the calculation of the surface tension from simulations of several models of water, such as the traditional TIP3P, SPC, SPC/E, and TIP4P models, and the new generation of TIP4P-like models including the TIP4P/Ew, TIP4P/Ice, and TIP4P/2005. We employ a thermodynamic route proposed by Gloor et al. J. Chem. Phys. 123, 134703 2005 to determine the surface tension that involves the estimate of the change in free energy associated with a small change in the interfacial area at constant volume. The values of the surface tension computed from this test-area method are found to be fully consistent with those obtained from the standard mechanical route, which is based on the evaluation of the components of the pressure tensor. We find that most models do not reproduce quantitatively the experimental values of the surface tension of water. The best description of the surface tension is given by those models that provide a better description of the vapor-liquid coexistence curve. The values of the surface tension for the SPC/E and TIP4P/Ew models are found to be in reasonably good agreement with the experimental values. From the present investigation, we conclude that the TIP4P/2005 model is able to accurately describe the surface tension of water over the whole range of temperatures from the triple point to the critical temperature. We also conclude that the test area is an appropriate methodological choice for the calculation of the surface tension not only for simple fluids, but also for complex molecular polar fluids, as is the case of water