The period-index problem and Hodge theory

Conditional on the Lefschetz standard conjecture in degree 2, we prove that the index of a Brauer class on a smooth projective variety divides a fixed power of its period, uniformly in smooth families. In the other direction, we reinterpret in more classical terms recent work of Hotchkiss which gives Hodge-theoretic lower bounds on the index of Brauer classes. We also prove versions of our results over arbitrary algebraically closed base fields, and as an application construct qualitatively new counterexamples to the integral Tate conjecture.Comment: 35 page

Comparison of Data Mining and Mathematical Models for Estimating Fuel Consumption of Passenger Vehicles

A number of analytical models have been described in the literature to estimate the fuel consumption of vehicles, most of which require a wide range of vehicle and trip related parameters as input data, which might limit the practical applicability of these models if such data were not readily available. To overcome this drawback, this study describes the development of three data mining models to estimate fuel consumption of a vehicle, including linear regression, artificial neural network and support vector machines. The paper presents comparison results with five instantaneous fuel consumption models from the literature using real data collected from three passenger vehicles on three routes. The results indicate that while the prediction accuracy of the instantaneous fuel consumption models varies across the data sets, those obtained by the regression models are significantly better and more robust against changes in input data

Cuba: Economía en Recuperación

La situación en Cuba, en los primeros años de la década de los 90, fue muy compleja y cargada de acontecimientos que afectaron en gran medida el desarrollo de nuestra economía, los que se iniciaron con los cambios sufridos en la exURSS y Europa del Este y la pérdida de los mercados de importación y exportación que se habían consolidado durante más de 30 años, manteniendo relaciones comerciales mutuamente ventajosas con todos los países de esa área geográfica. En este sentido, disminuyeron nuestras importaciones en un 85%, debimos reducir nuestras importaciones de petróleo, principal fuente energética, a la mitad (alrededor de 7 millones de toneladas) y recortar drásticamente nuestras inversiones. Entre 1990 y 1993, nuestro Producto Interno Bruto disminuyó en más de un tercio. Para enfrentar la grave situación que sobrevino, el Gobierno cubano adoptó un Programa de Emergencia Nacional, al cual denomina Programa del Periodo Esuecial en Tiemuo de Paz

Hemodynamic Alterations in Multiple Sclerosis

Multiple Sclerosis is an autoimmune disease of the central nervous system. It is a demyelinating and neurodegenerative condition, however, changes in the vasculature can occur and play a role in the pathophysiology. Cardiac and vascular risk factors contribute to the disease severity. Understanding the occurring hemodynamic changes may potentially lead to improved diagnosis, better patient management, and prevention of disease progression. This paper discusses the hemodynamic impairment in multiple sclerosis focusing on both the cerebral and cervical regions and presents an up-to-date review of the literature

Avaliação de Cimentos Endodônticos Biocerâmicos

A obturação do canal radicular tem como principal objetivo impedir o tráfego de fluidos dostecidos perirradiculares para o seu interior, assim como de microrganismos e seus fatores devirulência e antígenos, do canal radicular para os tecidos perirradiculares (Siqueira Jr.,2011)

Pengaruh Pendekatan Contextual Teaching And Learning (Ctl) terhadap Hasil Belajar IPS Siswa Sekolah Dasar ( Studi Eksperimen Siswa Kelas III Sdn 005 Makmur )

This research is motivated by the problem of low yields third grade social studies students of SDN 005 Makmur. Causative factor of such students are passive students in learning activities, students do not develop material to a wider scope and students have not been able to associate the concepts that have been studied with everyday life. This research is an experimental research, the research was conducted 4 meetings and the control class 4 meetings experimental class, where before entering the first meeting of each class in different days, both classes are given about Pree test, and after the meeting to four each -masing classes are also given about the post-test. In this study, researchers applied the approach Contextual Teaching and Learning (CTL). Subjects were IIIa class, there are 26 students and class IIIb as many as 26 students. Implemented in the second semester of academic year 2014/2015 on 16 April to 15 May 2015. Data collection techniques include test results of study and documentation of learning activities. Having done the research and data analysis, that the results of the acquisition Pree disimpulkanlah test the experimental class with an average of 65.04 and the control class with an average of 59.57, the results of the test data processing Pree T test showed t ≤ t table or 0.135 ≤ 2.021, so Ho accepted and Ha rejected. In other words, the mean scores test Pree there are no significant differences in learning outcomes. While the results of the acquisition of post-test scores in the experimental class with an average of 75.65 and the control class with an average of 73.77 then the data processing post-test t test seen that t ≤ t table ≤ 2,021 or 0,066, so Ho accepted and Ha rejected. In other words, the mean score of post test results to learn there are no significant differences