Dependent Random Graphs and Multiparty Pointer Jumping

We initiate a study of a relaxed version of the standard Erdos-Renyi random graph model, where each edge may depend on a few other edges. We call such graphs "dependent random graphs". Our main result in this direction is a thorough understanding of the clique number of dependent random graphs. We also obtain bounds for the chromatic number. Surprisingly, many of the standard properties of random graphs also hold in this relaxed setting. We show that with high probability, a dependent random graph will contain a clique of size $\frac{(1-o(1))\log n}{\log(1/p)}$, and the chromatic number will be at most $\frac{n \log(1/1-p)}{\log n}$. As an application and second main result, we give a new communication protocol for the k-player Multiparty Pointer Jumping (MPJ_k) problem in the number-on-the-forehead (NOF) model. Multiparty Pointer Jumping is one of the canonical NOF communication problems, yet even for three players, its communication complexity is not well understood. Our protocol for MPJ_3 costs $O(\frac{n\log\log n}{\log n})$ communication, improving on a bound of Brody and Chakrabarti [BC08]. We extend our protocol to the non-Boolean pointer jumping problem $\widehat{MPJ}_k$, achieving an upper bound which is o(n) for any $k >= 4$ players. This is the first o(n) bound for $\widehat{MPJ}_k$ and improves on a bound of Damm, Jukna, and Sgall [DJS98] which has stood for almost twenty years.Comment: 18 page

Dependent Random Graphs And Multi-Party Pointer Jumping

We initiate a study of a relaxed version of the standard Erdos-Renyi random graph model, where each edge may depend on a few other edges. We call such graphs dependent random graphs . Our main result in this direction is a thorough understanding of the clique number of dependent random graphs. We also obtain bounds for the chromatic number. Surprisingly, many of the standard properties of random graphs also hold in this relaxed setting. We show that with high probability, a dependent random graph will contain a clique of size ((1-o(1))log(n))/log(1/p), and the chromatic number will be at most (nlog(1/(1-p)))/log(n). We expect these results to be of independent interest. As an application and second main result, we give a new communication protocol for the k-player Multi-Party Pointer Jumping problem (MPJk) in the number-on-the-forehead (NOF) model. Multi-Party Pointer Jumping is one of the canonical NOF communication problems, yet even for three players, its communication complexity is not well understood. Our protocol for MPJ3 costs O((n * log(log(n)))/log(n)) communication, improving on a bound from [BrodyChakrabarti08]. We extend our protocol to the non-Boolean pointer jumping problem, achieving an upper bound which is o(n) for any k \u3e= 4 players. This is the first o(n) protocol and improves on a bound of Damm, Jukna, and Sgall, which has stood for almost twenty years

Análisis multiescala de un reactor de lecho percolado para un proceso de hds mediante cfd

En este trabajo se presenta un análisis multiescala de un reactor de lecho percolado en el que tiene lugar una reacción de Hidrodesulfurización de gasóleo ligero y en donde la velocidad de reacción sigue una cinética heterogénea del tipo Langmuir/Hinshelwood Hougen/Watson (LHHW). Las escalas estudiadas fueron: (1) escala a nivel de poros en el catalizador, (2) escala a nivel de una partícula catalítica y (3) escala de un clúster de partículas catalíticas, representando al reactor. El estudio se llevó a cabo mediante la técnica de Computer Fluid Dynamics (CFD por sus siglas en inglés). En las diferentes escalas se tienen diversos objetivos de estudios: A escala poros se analizó el efecto de la microestructura de la red de poros en el comportamiento cinético, térmico y el factor de efectividad de un catalizador. A escala catalizador se analizó el efecto de la representación de geométrica de la microestructura de la red de poros en el pelle catalítico sobre los coeficientes efectivos de transporte y sobre el comportamiento cinético, térmico y el factor de efectividad de un catalizador. A escala de un conjunto de partículas catalíticas (Modelo representativo del Reactor) se estudió: (a) el efecto de la geometría del catalizador en el comportamiento hidrodinámico del Reactor de lecho escurrido (TBR por sus siglas en inglés) en donde dos fases fluidas interactúan con una fase sólida; (b) el efecto de los diferentes modelos de intercambio de momento entre fases sobre el comportamiento hidrodinámico del TBR; (c) el efecto de la geometría del catalizador y del modelo de intercambio de momento entre fases sobre el comportamiento hidrodinámico, cinético y térmico del TBR; y (d) el efecto de la representación geométrica de la microestructura de los poros del catalizador sobre el comportamiento cinético y térmico del TBR a través de los valores calculados de los coeficientes efectivos de transporte de energía y masa

Rhynchomeliola Speg., un viejo género nuevo para Argentina

Al estudiar los micromicetes asociados a plantas nativas de los bosques andinopatagónicos, se coleccionaron ejemplares de dos especies de Rhynchomeliola Speg.: R. lomatiae S. Lee & Joanne E. Taylor creciendo sobre hojas de Lomatia ferruginea (Proteaceae), y R. usteriana (Speg.) Arx & Müller asociado a corteza de Nothofagus pumilio (Nothofagaceae). Rhynchomeliola es un género de posición incierta que reúne pocas especies, mayormente folícolas y tropicales, caracterizadas por poseer ascomas periteciales no estromáticos, de cuellos largos y delgados. En Sudamérica este género solo se conocía en Brasil, siendo esta la primera cita del mismo para Argentina. Asimismo este es el primer hallazgo de R. lomatiae desde su descripción original de material herborizado de Lomatia polymorpha proveniente de Australia. El descubrimiento de R. usteriana sobre corteza representa la primera descripción de una especie del género sobre un sustrato lignificado, y sustentaría el rechazo del hábito como carácter válido para distinguir Rhynchomeliola respecto del género afín Rhynchostoma P. Karst. Se proveen descripciones e ilustraciones completas de las especies encontradas, así como de los tipos de las especies descriptas por Spegazzini.During a survey of the micromycetes growing on native plants from the Patagonian Andean forests, two species of Rhynchomeliola Speg. were found: R. lomatiae S. Lee & Joanne E. Taylor growing on leaves of Lomatia ferruginea (Proteaceae), and R. usteriana (Speg.) Arx & Müller growing on bark of Nothofagus pumilio (Nothofagaceae). Rhynchomeliola is a small genus of long-necked, non stromatic, perithecial fungi which comprises nine species that are mostly tropical and foliicolous. In South America this genus was known only from Brazil. Rhynchomeliola lomatiae is recorded for the first time since its original description from herbarium material of Lomatia polymorpha in Australia. The finding of R. usteriana growing on bark is the first record of a Rhynchomeliola species on a lignified substrate and supports the rejection of the habit as a useful character to distinguish the genus from the morphologically akin Rhynchostoma P. Karst. Full descriptions and illustrations of the recorded species are provided along with those of the type materials of the species described by Spegazzini.Fil: Bianchinotti, Maria Virginia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; ArgentinaFil: Sanchez, Romina Magali. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Sur. Departamento de Biología, Bioquímica y Farmacia; ArgentinaFil: Rajchenberg, Mario. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Centro de Investigación y Extensión Forestal Andino Patagónico; Argentin

The effect of child labor on mathematics and language achievement in Latin America

The authors use a unique data set on language, and mathematics test scores for third, and fourth graders in eleven different Latin American countries, to determine whether child labor raises or lowers school achievement. Their findings are amazingly consistent across countries. In every country, child labor lowers performance on tests of language and mathematics proficiency, even when controlling for school and household attributes. The magnitude of the effect is similar to the percentage reduction in adult wages from child labor reported by Ilahi, Sedlacek and Orazem. The adverse impact of child labor on test performance is larger when children work regularly, rather than occasionally. Even modest levels of child labor at early ages cause adverse consequences for the development of cognitive abilities. These findings strongly refute the presumptions that child labor may be neutral, or complementary to academic performance, provided that the child remains enrolled in school. Instead, child labor consistently makes a year of education less productive in the generation of human capital.

Characterization of ENSO in a stratosphere-resolving version of the EC-EARTH model: comparison with observations and with the low-top version

Màster de Meteorologia, Facultat de Física, Universitat de Barcelona, Curs: 2019-2020, Tutors: Ileana Bladé Mendoza, Javier García SerranoA stratosphere-resolving configuration (HIGH-TOP) of the EC-EARTH global climate model (GCM) is used to characterize the El Ni~no-Southern Oscillation (ENSO) and compare it to observations. Despite the state of the art stratosphere, HIGH-TOP still presents some biases in the seasonal cycle and in the ENSO spatial pattern common to other GCMs. The interannual peak in the Ni~no3.4 index power spectrum is broadly captured, but the model is biased towards lower frequencies. To assess the effects of a well-resolved stratosphere in the tropical Pacific and, in particular, on ENSO, HIGH-TOP is compared with a low-top version of the model (LOW-TOP). HIGH-TOP displays systematic and statistically significant higher interannual variability in the central-eastern Pacific, along with an improvement in the ENSO pattern of sea surface temperature (SST) anomalies. The comparison of the ENSO-induced tropospheric circulation anomalies reveals a strengthening of the eastern Pacifc intertropical convergence zone (ITCZ) in HIGH-TOP with respect to LOW-TOP. Additionally, in the equatorial eastern Pacific, HIGH-TOP correctly simulates anomalous upward motion, while LOW-TOP simulates anomalous downward motion that enhances the climatological Walker circulation. The stronger ITCZ and the anomalous ascent in the eastern equatorial Pacific in HIGH-TOP are consistent with the higher total interannual variability in SST and precipitation in HIGH-TOP. Hence, incorporating a well-resolved stratosphere in the EC-EARTH model yields a more realistic representation of the variability in the central-eastern Pacific and tropical ENSO pattern