Un estudio sobre la construcción social de la noción de promedio en un contexto probabilística

Uno de los objetivos del presente trabajo es detectar los motivos por los cuales el concepto de promedio aritmético está tan arraigado en el estudiante que no puede desprenderse de él y lo interpola a otros ámbitos del quehacer matemático, específicamente al probabilístico. Se busca entender, mediante la línea de investigación conocida como la construcción social del conocimiento matemático, por qué los alumnos tienen problemas en aceptar y reconocer al valor esperado, conocido también como media o esperanza matemática, como un promedio en un nuevo escenario con nuevas características

Poor electronic screening in lightly doped Mott insulators observed with scanning tunneling microscopy

The effective Mott gap measured by scanning tunneling microscopy (STM) in the lightly doped Mott insulator $(\rm{Sr}_{1 -x}\rm{La}_x)_2\rm{IrO}_4$ differs greatly from values reported by photoemission and optical experiments. Here, we show that this is a consequence of the poor electronic screening of the tip-induced electric field in this material. Such effects are well known from STM experiments on semiconductors, and go under the name of tip-induced band bending (TIBB). We show that this phenomenon also exists in the lightly doped Mott insulator $(\rm{Sr}_{1 -x}\rm{La}_x)_2\rm{IrO}_4$ and that, at doping concentrations of $x\leq 4 \%$, it causes the measured energy gap in the sample density of states to be bigger than the one measured with other techniques. We develop a model able to retrieve the intrinsic energy gap leading to a value which is in rough agreement with other experiments, bridging the apparent contradiction. At doping $x \approx 5 \%$ we further observe circular features in the conductance layers that point to the emergence of a significant density of free carriers in this doping range, and to the presence of a small concentration of donor atoms. We illustrate the importance of considering the presence of TIBB when doing STM experiments on correlated-electron systems and discuss the similarities and differences between STM measurements on semiconductors and lightly doped Mott insulators.Comment: 9 pages, 5 figure

Closed-loop Frequency Tracking and Rejection

This paper develops an adaptive controller for active vibration control. The method is based on the LQG approach via disturbance modelling given in De Nicolao [1]. This approach to the narrow band disturbance rejection problem is then applied to the problem of eliminating the effects of roll eccentricity in steelstrip rolling mills

Scenarios for oil palm expansion in degraded and deforested lands in the Brazilian Amazon to meet biodiesel demand

Palm oil production for biodiesel in Brazil is characterized by its high productivity in some environmental conditions, under the Sustainable Palm Oil Production Program. The program seeks to avoid deforestation for oil palm cultivation, recover degraded lands, and focus on social inclusion and family farming. This paper assesses the possible socio-environmental impacts of the expansion of palm oil until 2030, focusing on land-use change and impacts. Land-use data came from the TerraClass initiative for the analysis of degraded forests using geoprocessing. We produced two oil expansion scenarios. The first one reflects current trends in palm oil production expansion and deforestation in Pará State (S1). The second one considers the exclusive use of deforested/degraded land for oil palm crops (S2). The results demonstrate that degraded/deforested land in the current palm oil-producing municipalities is only sufficient for the projected level of expansion for 2020, requiring a stronger public policy to recover degraded areas for oil palm cultivation with social inclusion of family farming.Palm oil production for biodiesel in Brazil is characterized by its high productivity in some environmental conditions, under the Sustainable Palm Oil Production Program. The program seeks to avoid deforestation for oil palm cultivation, recover degraded lands, and focus on social inclusion and family farming. This paper assesses the possible socio-environmental impacts of the expansion of palm oil until 2030, focusing on land-use change and impacts. Land-use data came from the TerraClass initiative for the analysis of degraded forests using geoprocessing. We produced two oil expansion scenarios. The first one reflects current trends in palm oil production expansion and deforestation in Pará State (S1). The second one considers the exclusive use of deforested/degraded land for oil palm crops (S2). The results demonstrate that degraded/deforested land in the current palm oil-producing municipalities is only sufficient for the projected level of expansion for 2020, requiring a stronger public policy to recover degraded areas for oil palm cultivation with social inclusion of family farming.Palm oil production for biodiesel in Brazil is characterized by its high productivity in some environmental conditions, under the Sustainable Palm Oil Production Program. The program seeks to avoid deforestation for oil palm cultivation, recover degraded lands, and focus on social inclusion and family farming. This paper assesses the possible socio-environmental impacts of the expansion of palm oil until 2030, focusing on land-use change and impacts. Land-use data came from the TerraClass initiative for the analysis of degraded forests using geoprocessing. We produced two oil expansion scenarios. The first one reflects current trends in palm oil production expansion and deforestation in Pará State (S1). The second one considers the exclusive use of deforested/degraded land for oil palm crops (S2). The results demonstrate that degraded/deforested land in the current palm oil-producing municipalities is only sufficient for the projected level of expansion for 2020, requiring a stronger public policy to recover degraded areas for oil palm cultivation with social inclusion of family farming.Palm oil production for biodiesel in Brazil is characterized by its high productivity in some environmental conditions, under the Sustainable Palm Oil Production Program. The program seeks to avoid deforestation for oil palm cultivation, recover degraded lands, and focus on social inclusion and family farming. This paper assesses the possible socio-environmental impacts of the expansion of palm oil until 2030, focusing on land-use change and impacts. Land-use data came from the TerraClass initiative for the analysis of degraded forests using geoprocessing. We produced two oil expansion scenarios. The first one reflects current trends in palm oil production expansion and deforestation in Pará State (S1). The second one considers the exclusive use of deforested/degraded land for oil palm crops (S2). The results demonstrate that degraded/deforested land in the current palm oil-producing municipalities is only sufficient for the projected level of expansion for 2020, requiring a stronger public policy to recover degraded areas for oil palm cultivation with social inclusion of family farming

Quantitative Characteristics of Human-Written Short Stories as a Metric for Automated Storytelling

Evaluating the extent to which computer-produced stories are structured like human-invented narratives can be an important component of the quality of a story plot. In this paper, we report on an empirical experiment in which human subjects have invented short plots in a constrained scenario. The stories were annotated according to features commonly found in existing automatic story generators. The annotation was designed to measure the proportion and relations of story components that should be used in automatic computational systems for matching human behaviour. Results suggest that there are relatively common patterns that can be used as input data for identifying similarity to human-invented stories in automatic storytelling systems. The found patterns are in line with narratological models, and the results provide numerical quantification and layout of story components. The proposed method of story analysis is tested over two additional sources, the ROCStories corpus and stories generated by automated storytellers, to illustrate the valuable insights that may be derived from them

Relative and Attributable Risk for Cervical Cancer: A Comparative Study in the United States and Italy

Parazzini F {Istituto di Ricerche Farmacologiche ‘Mario Negri' via Eritrea 62,20157 Milan, Italy), Hildesheim A, Ferraroni M, La Vecchia C and Brinton LA. Relative and attributable risk for cervical cancer: A comparative study in Italy and the United States. International Journal of Epidemiology 1990, 19: 539-545. The attributable risk for invasive cervical cancer in the US and Italian populations has been estimated in relation to main ‘aetiological' factors (number of sexual partners, age at first intercourse, parity, oral contraceptive use and smoking) and history of Pap smear using data from two case-control studies conducted in the US (466 cases and 788 controls) and Italy (528 cases and 456 controls). The risk of cervical cancer increased in both studies with multiple sexual partners, decreasing age at first intercourse, higher parity, oral contraceptive use and smoking. Levels of exposure to various risk factors were markedly different in the two countries (ie number of sexual partners, frequency of oral contraceptive use and smoking were greater in the US). Multiple Pap smears and a short interval since last Pap smear strongly reduced risk of cervical cancer in both populations, although screening was much more widespread in the US study population, with only 9% of controls reporting no previous smear versus 38% of the Italian control series. The combined population attributable risk for the five ‘aetiological' risk factors was slightly greater in the US study (76%) than in the Italian one (69%), chiefly because of a higher prevalence of exposure to sexual factors in US study women. A substantially larger proportion of Italian cases were due in part to deficiency in screening (46% in US and 84% in Italy). Thus, further inclusion of the effect of screening programmes (number of Pap smears and time since last Pap) led to an overall proportion of cases attributable to the examined risk factors of 87% in the US and 95% in Ital

Disentangling PTEN-cooperating tumor suppressor gene networks in cancer.

We have recently performed a whole-body, genome-wide screen in mice using a single-copy inactivating transposon for the identification of Pten (phosphatase and tensin homolog)-cooperating tumor suppressor genes (TSGs). We identified known and putative TSGs in multiple cancer types and validated the functional and clinical relevance of several promising candidates for human prostate cancer

Nonlinear Multigrid for Reservoir Simulation

Summary A feasibility study is presented on the effectiveness of applying nonlinear multigrid methods for efficient reservoir simulation of subsurface flow in porous media. A conventional strategy modeled after global linearization by means of Newton’s method is compared with an alternative strategy modeled after local linearization, leading to a nonlinear multigrid method in the form of the full-approximation scheme (FAS). It is demonstrated through numerical experiments that, without loss of robustness, the FAS method can outperform the conventional techniques in terms of algorithmic and numerical efficiency for a black-oil model. Furthermore, the use of the FAS method enables a significant reduction in memory usage compared with conventional techniques, which suggests new possibilities for improved large-scale reservoir simulation and numerical efficiency. Last, nonlinear multilevel preconditioning in the form of a hybrid-FAS/Newton strategy is demonstrated to increase robustness and efficiency.</jats:p