Stable matchings and linear programming

AbstractThis paper continues the work of Abeledo and Rothblum, who study nonbipartite stable matching problems from a polyhedral perspective. We establish here additional properties of fractional stable matchings and use linear programming to obtain an alternative polynomial algorithm for solving stable matching problems

Ambigüedad y objetividad en los condicionales contrafácticos

Los contrafácticos han suscitado muchas polémicas. Una de ellas ha girado alrededor del grado de vaguedad que los afecta. Otra, alrededor de la posibilidad de fijar criterios de verdad claros y no sujetos a arbitrariedades. Algunos autores (en especial y paradigmáticamente D. Lewis, cuya teoría de los contrafácticos se ha convertido en la principal referencia sobre el tema) proponen un análisis semántico que fija con toda precisión las condiciones de verdad. Pero su aplicación depende de un cierto factor -relación de ordenamiento para Lewis, función de selección para Stalnaker, etc.- que será elegido a su vez por consideraciones pragmáticas, y que será el que carga con la vaguedad. En el caso de Lewis se puede decir (en forma por demás simplificada) que el condicional contrafáctico 'si fuera el caso que A seria el caso que C' será verdadero si el consecuente C se cumple en los mundos que se asemejan más al mundo efectivo entre aquellos en que se cumple el antecedente. Fijado un criterio de semejanza, o en palabras de Lewis, una relación de similaridad comparativa global, la determinación del valor de verdad del contrafáctico dependerá exclusivamente de una investigación del mundo efectivo. No habrá ya lugar a vaguedad ni a subjetividad. Pero esta relación de similaridad comparativa global no parece poder ser impuesta en forma única, ni es algo que encontramos fuera de nosotros mismos

A collaboratively derived international research agenda on legislative science advice

The quantity and complexity of scientific and technological information provided to policymakers have been on the rise for decades. Yet little is known about how to provide science advice to legislatures, even though scientific information is widely acknowledged as valuable for decision-making in many policy domains. We asked academics, science advisers, and policymakers from both developed and developing nations to identify, review and refine, and then rank the most pressing research questions on legislative science advice (LSA). Experts generally agree that the state of evidence is poor, especially regarding developing and lower-middle income countries. Many fundamental questions about science advice processes remain unanswered and are of great interest: whether legislative use of scientific evidence improves the implementation and outcome of social programs and policies; under what conditions legislators and staff seek out scientific information or use what is presented to them; and how different communication channels affect informational trust and use. Environment and health are the highest priority policy domains for the field. The context-specific nature of many of the submitted questions—whether to policy issues, institutions, or locations—suggests one of the significant challenges is aggregating generalizable evidence on LSA practices. Understanding these research needs represents a first step in advancing a global agenda for LSA research.Fil: Akerlof, Karen. George Mason University; Estados UnidosFil: Tyler, Chris. University College London;Fil: Foxen, Sarah Elizabeth. University College London;Fil: Heath, Erin. American Association for the Advancement of Science; Estados UnidosFil: Gual Soler, Marga. American Association for the Advancement of Science; Estados UnidosFil: Allegra, Alessandro. University College London;Fil: Cloyd, Emily T.. American Association for the Advancement of Science; Estados UnidosFil: Hird, John A.. University of Massachussets; Estados UnidosFil: Nelson, Selena M.. George Mason University; Estados UnidosFil: Nguyen, Christina T.. George Mason University; Estados UnidosFil: Gonnella, Cameryn J.. Herndon; Estados UnidosFil: Berigan, Liam A.. Kansas State University; Estados UnidosFil: Abeledo, Carlos R.. Universidad de Buenos Aires; ArgentinaFil: Al Yakoub, Tamara Adel. Yarmouk University; JordaniaFil: Andoh, Harris Francis. Tshwane University Of Technology; Sudáfrica. Tshwane University of Technology; GhanaFil: dos Santos Boeira, Laura. Veredas Institute; BrasilFil: van Boheemen, Pieter. Rathenau Instituut; Países BajosFil: Cairney, Paul. University of Stirling; Reino UnidoFil: Cook Deegan, Robert. Arizona State University; Estados UnidosFil: Costigan, Gavin. Foundation For Science And Technology; Reino UnidoFil: Dhimal, Meghnath. Nepal Health Research Council; NepalFil: Di Marco, Martín Hernán. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Sociales. Instituto de Investigaciones "Gino Germani"; ArgentinaFil: Dube, Donatus. National University of Science and Technology; Zimbabu

Grain yield and kernel setting of multiple-shoot and/or multiple-ear maize hybrids

Rainfed maize (Zea mays L.) crops in low-rainfall regions are cultivated at very low plant population densities that favor the production of fertile tillers or multiple ears in the main shoot. Little information exists regarding the functional processes governing grain yield and kernel setting on ears of different order of shoots of maize crops. To study these functional processes, field experiments were conducted cultivating two commercial maize hybrids (AX7784 and DM2738) under supplementary irrigation using different plant densities, N rates at sowing, shading around female flowering (silking) and tiller removal treatments. Hybrids differed in the number of tillers per plant at R1 (AX7784 > DM2738). Early tiller removal increased main shoot growth rate around silking, suggesting competition for light among shoots. Kernel number per plant was positively and curvilinearly related with plant growth rate around silking, i.e. critical period (PGRCP), in tillered and non-tillered plants of both hybrids. Tillered plants set higher kernel numbers than non-tillered plants at PGRCP > 9 g pl-1 d-1 (AX7784) or 11 g pl-1 d-1 (DM2738), while the opposite trend occurred at PGRCP values AX7784) and tillers (AX7784 > DM2738). The different pattern of kernel setting between hybrids was explained by differences in the biomass partitioning to tiller ears and the reproductive efficiency of ears of tillers (AX7784 > DM2738), and both the biomass partitioning to and the reproductive efficiency of second and third order ears of main shoots (DM2738 > AX7784). Kernel number per plant was higher for DM2738 due to a higher kernel setting on multiple ears of main shoot plus tillers (more prolific and with lower tiller fertility) than for AX7784 (less prolific and with higher tiller fertility). However, grain yield did not differ between hybrids, because of the higher kernel weight of AX7784. Therefore, this work opens avenues for exploiting higher grain yields in maize crops with low plant population densities through the combination of prolificacy and tillering. Further studies should analyze the impact of reproductive plasticity on kernel weight determination in low-density maize crops.Fil: Rotili, Diego Hernán. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Abeledo, Leonor Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Martínez Larrea, Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Maddonni, Gustavo Angel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentin

Exploring the effect of tillers on the water economy, plant growth and kernel set of low-density maize crops

In semi-arid production regions having a high inter-annual rainfall variability, farmers use low plant densities, that promote tillering in maize (Zea mays L.). Tillering in maize is a scarcely researched trait, even though it offers vegetative and reproductive plasticity. However, the production of tillered maize crops may be risky due to a possible early soil water depletion and/or low reproductive efficiency. Here, we explored the potential effects of tillers (0, 1 and 2 tillers pl) on the water economy, plant growth and kernel set of maize crops at a low plant density (2 pl m) through the combination of simulations (using an adapted version of APSIM Sorghum model) and field experiments. The simulated scenarios included six locations across Argentina and Australia and three levels of available soil water content at sowing (50 %, 70 % and 90 %). In humid environments, simulated crops with increased number of tillers pl expressed high vegetative plasticity (up to three-fold increases in leaf area index at flowering), driving high values of crop evapotranspiration during the pre-flowering period (Eta). In drier environments, simulated Eta was similar between crops with different tiller number pl. Manipulative field experiments were established to parameterize the function between kernel number per plant (KNP) as a function of plant growth rate around flowering (PGR) for tillered and non-tillered plants. At low PGR, tillered plants had lower KNP than non-tillered plants, though the opposite was evident at high PGR. Interestingly, when simulated PGR values were used to predict kernel number m (KN m), increases in KN m of tillered maize crops in humid environments were larger than the decreases in drier environments. Consequently, farmers could benefit by choosing tillering maize genotypes in the long term when sowing low plant densities

Progression of focal lupus nephritis with extracapillary proliferation after one year

Introduction: Although focal lupus nephritis (FLN) with extracapillary proliferation (ECP) is usually found in renal biopsies, little is known about its course. This study was carried out to investigate the correlation of clinical, histological and laboratory findings in these patients’ progress. Objective: To analyze focal or diffuse proliferative lupus nephritis biopsies (class III and IV, according to WHO) and their development regarding the level of extracapillary proliferation throughout a period of 10 years at Hospital de Clínicas José de San Martín. Methods: In this retrospective observational study, 147 patients with class III or IV GN were observed for 10 years. According to the degree of extracapillary proliferation, they were divided into the following groups: group 1 (5%-50% of crescents, i.e. diffuse proliferative nephritis (DPN), n=20]. Patients suffering from class III and IV lupus nephritis with no extracapillary proliferation formed the control group (n=60). After one year, clinical and laboratory findings as well as the development of the condition among the four groups were compared to assess their level of remission. Complete remission was considered as defined in KDIGO 2012 Guideline. A univariate logistic regression analysis and a subsequent multivariate one were performed. Results: There were 124 women (84.35%) and 23 men (15.65%) with an average age of 35±10. The average age in the control group was 32±10. The univariate analysis showed a greater number of patients who achieved complete remission in the control group with an odds ratio of 0.05 (0.02-0.12) p=0.001, whereas in the 3 groups with extracapillary proliferation fewer patients reached this state, even in group 1, which had an odds ratio of 7.61 (2.42-23.9) and p=0.001. The multivariate analysis revealed that the persistent protein in the urine after 6 months was statistically significant for not achieving complete remission, the odds ratio being 2.81 (1.58-5.0) and p=0.001. Conclusion: The presence of various degrees of crescent formation in class III and IV proliferative lupus nephritis (PLN) shown in the histological findings and the persistent protein in the urine at 6 months constitute independent factors for not achieving complete remission after one year