79 research outputs found
The Dynamic Effects of Information on Political Corruption: Theory and Evidence from Puerto Rico
Does the disclosure of information about corrupt activities induce a sustained reduction in corruption? We use publicly released routine audits of municipal governments in Puerto Rico to answer this question. We first develop a political agency model where voters re-elect incumbents based on their performance while in office. We show that, because voters cannot directly observe incumbents’ actions, an incumbent whose reputation improved in the previous term is likely to engage in more rent-seeking activities in a future term. Guided by this model, we use longitudinal data on audit results to examine the long-term consequences of providing information to voters on levels of political corruption. We find that municipal corruption levels in subsequent audits are on average the same in municipalities audited preceding the previous election and those not audited then. In spite of this, mayors in municipalities audited preceding the previous election have higher re-election rates, suggesting that audits enable voters to select more competent politicians. We conclude that short-term information dissemination policies do not necessarily align politicians’ long-term actions with voter preferences as politicians exploit their reputational gains by extracting more rents from office.corruption; information; political agency; dynamic incentives
The dynamic effects of information on political corruption: Theory and evidence from Puerto Rico
Does the disclosure of information about corrupt activities induce a sustained reduction in corruption? We use longitudinal data on audits of municipal governments in Puerto Rico to answer this question. We find that corruption is lower in municipalities audited before an election. However, these municipalities do not exhibit decreased levels of corruption in subsequent audits. Mayors in municipalities audited preceding the previous election have higher re-election rates, suggesting that audits enable voters to select more competent politicians. We present a political agency model that rationalizes the observed short-term and dynamic effects of information on corruption and re-election rates. We conclude that audit programs must be timely, sustained, and long-term commitments in order to be effective
Adenocarcinoma de la tercera porción duodenal moderadamente diferenciado
ResumenAntecedentesEl adenocarcinoma de duodeno es un tumor poco frecuente; representa el 33-45% de todos los tumores de intestino delgado. Los síntomas no son específicos, y el diagnóstico con frecuencia es accidental.Caso clínicoVarón de 35 años, que consulta por dolor abdominal posprandial. La endoscopia diagnosticó un tumor de la tercera porción duodenal (adenoma tubular con alto grado de displasia mediante la biopsia endoscópica). La tomografía computada, la resonancia magnética nuclear y la ecoendoscopia, mostraron un tumor de la tercera porción duodenal, sin metástasis linfáticas o peritoneales. Se realizó resección parcial del duodeno y el diagnóstico definitivo fue de adenocarcinoma de la tercera porción duodenal sobre adenoma tubular pT2N0M0.ConclusionesLas neoplasias de duodeno son muy raras. La duodenopancreatectomía cefálica se recomienda para los tumores de localización proximal, mientras que las resecciones segmentarias son apropiadas para localizaciones distales, con la misma supervivencia.AbstractBackgroundDuodenal carcinoma is very rare. It represents 33-45% of the all tumours of the small bowel. The symptoms are non-specific, and the diagnosis is often accidental.Clinical caseA 35-year old man was admitted to our hospital with post-prandial abdominal pain. Upper gastrointestinal examination revealed a tumour of the third duodenal portion, which was diagnosed, using endoscopic biopsy, as a tubular adenoma with high grade dysplasia. The computed axial tomography scan, the magnetic resonance imaging, and the endoscopic ultrasound showed the neoplasia of the third duodenal portion with no lymph node or peritoneal metastases. Partial resection of the duodenum was performed. The definitive histopathological diagnosis was primary adenocarcinoma of the third duodenal portion. pT2 N0M0, originated in a tubular adenoma.ConclusionsPrimitive neoplasia of the duodenum is very rare. Duodeno-cephalo-pancreatectomy is recommended in proximally located tumours, while segmental resection of the duodenum is appropriated for distal locations, with the same survival
Assessment of steady and unsteady friction models in the draining processes of hydraulic installations
The study of draining processes without admitting air has been conducted using only steady friction formulations in the implementation of governing equations. However, this hydraulic event involves transitions from laminar to turbulent flow, and vice versa, because of the changes in water velocity. In this sense, this research improves the current mathematical model considering unsteady friction models. An experimental facility composed by a 4.36 m long methacrylate pipe was configured, and measurements of air pocket pressure oscillations were recorded. The mathematical model was performed using steady and unsteady friction models. Comparisons between measured and computed air pocket pressure patterns indicated that unsteady friction models slightly improve the results compared to steady friction models
Assessment of Steady and Unsteady Friction Models in the Draining Processes of Hydraulic Installations
The study of draining processes without admitting air has been conducted using only steady friction formulations in the implementation of governing equations. However, this hydraulic event involves transitions from laminar to turbulent flow, and vice versa, because of the changes in water velocity. In this sense, this research improves the current mathematical model considering unsteady friction models. An experimental facility composed by a 4.36 m long methacrylate pipe was configured, and measurements of air pocket pressure oscillations were recorded. The mathematical model was performed using steady and unsteady friction models. Comparisons between measured and computed air pocket pressure patterns indicated that unsteady friction models slightly improve the results compared to steady friction models
Metodología para focalizar nuevos centros de atención para Personas con Discapacidad. Una aplicación del Análisis Multivariante
The main contribution of this article, based on the thesis written by the Gandy Rene López Fuertes MSc., this methodological proposal aims to focus new centers for the care of people with disabilities, in this sense the grouping of Ecuadorian parishes is carried out in order to generate possible scenarios for the creation of care centers for the people with disabilities that demand priority. The main source for the development of this model was the VII Population Census and VI Housing Census of 2010, from this source some sociodemographic variables were obtained, such as the incidence of people with disabilities, people with disabilities living in poverty due to unmet basic needs, among others. After applying multivariate statistical methods such as Factor Analysis, some variables were simplified, and the first two components were taken, for which it was possible to explain the variance of 88.6 % of the original data. In addition, thanks to the results obtained from the cluster analysis, it was possible to determine the three necessary groups of parishes that showed a certain level of priority. Finally, the group with the highest priority was Stratum 3, which corresponds to 378 (36.9 %) parishes whose conglomerate allowed the most vulnerable parishes in Ecuador to be classified, where the creation of new care centres is needed, with the intention that the Ministry of Economic and Social Inclusion can assist persons with disabilities.El aporte principal del presente artículo, se basa en la tesis escrita por el Ing. Gandy Rene López Fuertes MSc., esta propuesta metodológica tiene como objetivo focalizar nuevos centros para la atención de personas con discapacidad, en este sentido se lleva a cabo la agrupación de las parroquias ecuatorianas con el fin de generar posibles escenarios para la creación de centros de atención para la población con discapacidad que demanden prioridad. La fuente principal para la elaboración de este modelo fue el VII Censo de población y VI censo de vivienda del año 2010, de dicha fuente se obtuvieron algunas variables sociodemográficas, como la incidencia de personas con discapacidad, personas con discapacidad que viven en pobreza por necesidades básicas insatisfechas, entre otras. Luego de aplicar métodos estadísticos multivariantes como el Análisis Factorial, se simplificaron algunas variables, y se tomó los dos primeros componentes, para lo cual fue posible explicar la varianza del 88,6 % de los datos originales. Además, gracias a los resultados obtenidos del análisis de conglomerados, fue posible determinar los tres grupos de parroquias necesarios que mostraron cierto nivel de prioritaria. Finalmente, el grupo con más alta prioridad fue el Estrato 3, que corresponde a 378 (36,9 %) parroquias cuyo conglomerado permitió clasificar a las parroquias más vulnerables en el Ecuador, en las que se necesita la creación de nuevos centros de atención, con la intención de que el Ministerio de Inclusión Económica y Social pueda asistir a las personas con discapacidad
Simplified Mathematical Model for Computing Draining Operations in Pipelines of Undulating Profiles with Vacuum Air Valves
[EN] The draining operation involves the presence of entrapped air pockets, which are expanded
during the phenomenon occurrence generating drops of sub-atmospheric pressure pulses. Vacuum
air valves should inject enough air to prevent sub-atmospheric pressure conditions. Recently, this
phenomenon has been studied by the authors with an inertial model, obtaining a complex formulation
based on a system composed by algebraic-di erential equations. This research simplifies this complex
formulation by neglecting the inertial term, thus the Bernoulli¿s equation can be used. Results show
how the inertial model and the simplified mathematical model provide similar results of the evolution
of main hydraulic and thermodynamic variables. The simplified mathematical model is also verified
using experimental tests of air pocket pressure, water velocity, and position of the water column.Coronado-Hernández, ÓE.; Fuertes-Miquel, VS.; Quiñones-Bolaños, EE.; Gatica, G.; Coronado-Hernández, JR. (2020). Simplified Mathematical Model for Computing Draining Operations in Pipelines of Undulating Profiles with Vacuum Air Valves. Water. 12(9):1-12. https://doi.org/10.3390/w12092544S112129Fuertes-Miquel, V. S., Coronado-Hernández, O. E., Mora-Meliá, D., & Iglesias-Rey, P. L. (2019). Hydraulic modeling during filling and emptying processes in pressurized pipelines: a literature review. Urban Water Journal, 16(4), 299-311. doi:10.1080/1573062x.2019.1669188Fuertes-Miquel, V. S., Coronado-Hernández, O. E., Iglesias-Rey, P. L., & Mora-Meliá, D. (2018). Transient phenomena during the emptying process of a single pipe with water–air interaction. Journal of Hydraulic Research, 57(3), 318-326. doi:10.1080/00221686.2018.1492465Tijsseling, A. S., Hou, Q., Bozkuş, Z., & Laanearu, J. (2015). Improved One-Dimensional Models for Rapid Emptying and Filling of Pipelines. Journal of Pressure Vessel Technology, 138(3). doi:10.1115/1.4031508Coronado-Hernández, O. E., Fuertes-Miquel, V. S., Besharat, M., & Ramos, H. M. (2018). Subatmospheric pressure in a water draining pipeline with an air pocket. Urban Water Journal, 15(4), 346-352. doi:10.1080/1573062x.2018.1475578Ramezani, L., Karney, B., & Malekpour, A. (2016). Encouraging Effective Air Management in Water Pipelines: A Critical Review. Journal of Water Resources Planning and Management, 142(12), 04016055. doi:10.1061/(asce)wr.1943-5452.0000695Zhou, L., & Liu, D. (2013). Experimental investigation of entrapped air pocket in a partially full water pipe. Journal of Hydraulic Research, 51(4), 469-474. doi:10.1080/00221686.2013.785985Carlos, M., Arregui, F. J., Cabrera, E., & Palau, C. V. (2011). Understanding Air Release through Air Valves. Journal of Hydraulic Engineering, 137(4), 461-469. doi:10.1061/(asce)hy.1943-7900.0000324Bianchi, A., Mambretti, S., & Pianta, P. (2007). Practical Formulas for the Dimensioning of Air Valves. Journal of Hydraulic Engineering, 133(10), 1177-1180. doi:10.1061/(asce)0733-9429(2007)133:10(1177)Ramezani, L., Karney, B., & Malekpour, A. (2015). The Challenge of Air Valves: A Selective Critical Literature Review. Journal of Water Resources Planning and Management, 141(10), 04015017. doi:10.1061/(asce)wr.1943-5452.0000530Coronado-Hernández, O., Fuertes-Miquel, V., Besharat, M., & Ramos, H. (2017). Experimental and Numerical Analysis of a Water Emptying Pipeline Using Different Air Valves. Water, 9(2), 98. doi:10.3390/w9020098Laanearu, J., Annus, I., Koppel, T., Bergant, A., Vučković, S., Hou, Q., … van’t Westende, J. M. C. (2012). Emptying of Large-Scale Pipeline by Pressurized Air. Journal of Hydraulic Engineering, 138(12), 1090-1100. doi:10.1061/(asce)hy.1943-7900.0000631Coronado-Hernández, O. E., Fuertes-Miquel, V. S., Iglesias-Rey, P. L., & Martínez-Solano, F. J. (2018). Rigid Water Column Model for Simulating the Emptying Process in a Pipeline Using Pressurized Air. Journal of Hydraulic Engineering, 144(4), 06018004. doi:10.1061/(asce)hy.1943-7900.0001446Coronado-Hernández, O. E., Fuertes-Miquel, V. S., Iglesias-Rey, P. L., & Martínez-Solano, F. J. (2020). Closure to «Rigid Water Column Model for Simulating the Emptying Process in a Pipeline Using Pressurized Air» by Oscar E. Coronado-Hernández, Vicente S. Fuertes-Miquel, Pedro L. Iglesias-Rey, and Francisco J. Martínez-Solano. Journal of Hydraulic Engineering, 146(3), 07020002. doi:10.1061/(asce)hy.1943-7900.0001681Vasconcelos, J. G., & Wright, S. J. (2008). Rapid Flow Startup in Filled Horizontal Pipelines. Journal of Hydraulic Engineering, 134(7), 984-992. doi:10.1061/(asce)0733-9429(2008)134:7(984)Vasconcelos, J. G., Klaver, P. R., & Lautenbach, D. J. (2014). Flow regime transition simulation incorporating entrapped air pocket effects. Urban Water Journal, 12(6), 488-501. doi:10.1080/1573062x.2014.881892Wang, L., Wang, F., & Lei, X. (2018). Investigation on friction models for simulation of pipeline filling transients. Journal of Hydraulic Research, 56(6), 888-895. doi:10.1080/00221686.2018.1434693Malekpour, A., Karney, B. W., & Nault, J. (2016). Physical Understanding of Sudden Pressurization of Pipe Systems with Entrapped Air: Energy Auditing Approach. Journal of Hydraulic Engineering, 142(2), 04015044. doi:10.1061/(asce)hy.1943-7900.0001067Coronado-Hernández, Ó. E., Fuertes-Miquel, V. S., Mora-Meliá, D., & Salgueiro, Y. (2020). Quasi-static Flow Model for Predicting the Extreme Values of Air Pocket Pressure in Draining and Filling Operations in Single Water Installations. Water, 12(3), 664. doi:10.3390/w12030664Leon, A. S., Ghidaoui, M. S., Schmidt, A. R., & Garcia, M. H. (2010). A robust two-equation model for transient-mixed flows. Journal of Hydraulic Research, 48(1), 44-56. doi:10.1080/0022168090356591
Pores Formed by Baxα5 Relax to a Smaller Size and Keep at Equilibrium
AbstractPores made by amphipathic cationic peptides (e.g., antimicrobials and fragments of pore-forming proteins) are typically studied by examining the kinetics of vesicle leakage after peptide addition or obtaining structural measurements in reconstituted peptide-lipid systems. In the first case, the pores have been considered transient phenomena that allow the relaxation of the peptide-membrane system. In the second, they correspond to equilibrium structures at minimum free energy. Here we reconcile both approaches by investigating the pore activity of the α5 fragment from the proapoptotic protein Bax (Baxα5) before and after equilibrium of peptide/vesicle complexes. Quenching assays on suspensions of large unilamellar vesicles suggest that in the presence of Baxα5, the vesicles maintain a leaky state for hours under equilibrium conditions. We proved and analyzed stable pores on single giant unilamellar vesicles (GUVs) in detail by monitoring the entrance of dyes added at different times after incubation with the peptide. When the GUVs came in contact with Baxα5, leakage started stochastically, was delayed for various periods of time, and in the majority of cases proceeded rapidly to completion. After hours in the presence of the peptide, the same individual GUVs that refilled completely at first instance maintained a porated state, which could be observed in subsequent leak-in events for serially added dyes. However, these long-term pores were smaller in size than the initial equilibration pores. Stable pores were also detected in GUVs made in the presence of Baxα5. The latter pores can be considered equilibrium states and may correspond to structures measured previously in bilayer stacks. Although pore formation may occur as a kinetic process, equilibrium pores may also be functionally relevant structures, especially in highly regulated systems such as the apoptotic mitochondrial pores induced by Bax
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