Eigenvalue estimates for a class of elliptic differential operators in divergence form on Riemannian manifolds isometrically immersed in Euclidean space

In this paper, we obtain eigenvalue estimates for a larger class of elliptic differential operators in divergence form on a bounded domain in a complete Riemannian manifold isometrically immersed in Euclidean space. As an application, we give eigenvalue estimates in the Gaussian shrinking soliton, and we find a domain that makes the behavior of these estimates similar to the estimates for the case of the Laplacian. Moreover, we also give an answer to the generalized conjecture of P\'olya.Comment: 17 page

Estimates of eigenvalues of an elliptic differential system in divergence form

In this paper, we compute universal estimates of eigenvalues of a coupled system of elliptic differential equations in divergence form in a bounded domain in Euclidean space. As an application, we show an interesting case of rigidity inequalities of the eigenvalues of the Laplacian, more precisely, we consider a countable family of bounded domains in Gaussian shrinking soliton that makes the behavior of known estimates of the eigenvalues of the Laplacian invariant by a first-order perturbation of the Laplacian. We also address the Gaussian expanding soliton case.Comment: 23 page

Directed propaganda in the majority-rule model

Advertisement and propaganda have changed continuously in the past decades, mainly due to the people's interactions at online platforms and social networks, and operate nowadays reaching a highly specific online audience instead targeting the masses. The impacts of this new media effect, oriented directly for a specific audience, is investigated on this study, in which we focus on the opinion evolution of agents in the majority-rule model, considering the presence of directed propaganda. We introduce $p$ as the probability of a "positive" external propaganda and $q$ as the probability to the agents follow the external propaganda. Our results show that the usual majority-rule model stationary state is reached, with a full consensus, only for two cases, namely when the external propaganda is absent or when the media favors only one of the two opinions. However, even for a small influence of external propaganda, the final state is reached with a majority opinion dominating the population. For the case in which the propaganda influence is strong enough among the agents, we show that the consensus can not be reached at all. In addition, we show through analytical and numerical results that the system undergoes to an order-disorder transition that occurs at $q_c = 1/3$ for the case $p = 0.5$

Computational simulation of one-dimensional waves with the Multigrid Method / Simulação computacional de ondas unidimensionais com o Método Multigrid

Several Engineering problems are modeled computationally, these simulations involve large systems, which are commonly difficult to solve. This paper deals with the simulation of one-dimensional waves, where the system resulting from the discretization by the Finite Difference Method is solved using the Multigrid Method with the conventional Gauss-Seidel solver, in order to decrease the computational time. Temporal discretization using the Time-Stepping method, where the system of equations is solved at each time step sequentially

Duality and fields redefinition in three dimensions

We analyze local fields redefinition and duality for gauge field theories in three dimensions. We find that both Maxwell-Chern-Simons and the Self-Dual models admits the same fields redefinition. Maxwell-Proca action and its dual also share this property. We show explicitly that a gauge-fixing term has no influence on duality and fields redefinition.Comment: 8 pages, suppressed contents. To appear in J. Phys.

Interannual variability of the South Indian Countercurrent

Author Posting. © American Geophysical Union, 2016. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 121 (2016): 3465–3487, doi:10.1002/2015JC011417.In the present work, we investigate the interannual variability of the South Indian Countercurrent (SICC), a major and still understudied current of the Indian Ocean circulation. To characterize the interannual variability of the SICC, four different data sets (altimetry, GLORYS, OFAM3, and SODA) are analyzed using multiple tools, which include Singular Spectrum Analysis and wavelet methods. The quasi-biennial band dominates the SICC low-frequency variance, with the main peak in the 1.5–1.8 year interval. A secondary peak (2.1–2.5 year) is only found in the western basin. Interannual and decadal-type modulations of the quasi-biennial signal are also identified. In addition, limitations of SODA before the 1960s in the SICC region are revealed. Within the quasi-biennial band, the SICC system presents two main patterns with a multiple jet structure. One pattern is characterized by a robust northern jet, while in the other the central jet is well developed and northern jet is weaker. In both patterns, the southern jet has always a strong signature. When the northern SICC jet is stronger, the northern cell of the subtropical gyre has a triangular shape, with its southern limb having a strong equatorward slant. The quasi-biennial variability of the SICC is probably related to the Indian Ocean tropical climate modes that are known to have a strong biennial characteristic.ARC Discovery Project Grant Number: DP130102088; NSF Grant Number: OCE-091716; Ocean Science Division of VM Oceanica2016-11-2

Socioeconomic Gradients in Chronic Disease Risk Factors in Middle-Income Countries: Evidence of Effect Modification by Urbanicity in Argentina

Objectives. We investigated associations of socioeconomic position (SEP) with chronic disease risk factors, and heterogeneity in this patterning by provincial-level urbanicity in Argentina. Methods. We used generalized estimating equations to determine the relationship between SEP and body mass index, high blood pressure, diabetes, low physical activity, and eating fruit and vegetables, and examined heterogeneity by urbanicity with nationally representative, cross-sectional survey data from 2005. All estimates were age adjusted and gender stratified. Results. Among men living in less urban areas, higher education was either not associated with the risk factors or associated adversely. In more urban areas, higher education was associated with better risk factor profiles (P<.05 for 4 of 5 risk factors). Among women, higher education was associated with better risk factor profiles in all areas and more strongly in more urban than in less urban areas (P<0.05 for 3 risk factors). Diet (in men) and physical activity (in men and women) were exceptions to this trend. Conclusions. These results provide evidence for the increased burden of chronic disease risk among those of lower SEP, especially in urban areas

Utjecaj organskih otapala na značajke slobodne i imobilizirane inulinaze, izolirane iz kvasca Kluyveromyces marxianus ATCC 16045

The aim of this work is to evaluate the effects of the butyl acetate concentration on the characteristics of free and immobilized inulinase from Kluyveromyces marxianus ATCC 16045. The mass fractions of organic solvent (OS) in sodium acetate buffer (0.1 M) were studied in the range from 25 to 70 %. The characteristics of both free and immobilized enzymes were not significantly affected by the OS mass fraction. The optimal temperature for the free enzyme was 55 °C at all OS mass fractions studied, whereas for the immobilized enzyme the optimum was 55 °C at 70 % of butyl acetate, and in the range from 50 to 60 °C at 25 and 50 % of OS. The optimum pH values, at all OS mass fractions, were 4.8 and 4.4 for the free and immobilized enzymes, respectively. The immobilized enzyme showed more stability at 50 °C and pH=4.8 for the whole range of OS mass fractions, since its stability was improved about 3 times. The kinetics parameters were calculated using Lineweaver-Burk plots. For the free enzyme, the vmax values were 12.5, 58.5 and 37.6 U/mL and the Km values 17.5, 280.7 and 210.4 mM at butyl acetate mass fractions of 25, 50 and 70 %, respectively. Similarly, for the immobilized enzyme, the vmax values were 38.9, 59.5 and 72.5 U/mL and the Km values 3.1, 5.4 and 14.0 mM at the same butyl acetate mass fractions, respectively.Svrha je ovoga rada bila procijeniti utjecaj koncentracije butilnog acetata na značajke slobodne i imobilizirane inulinaze, izolirane iz kvasca Kluyveromyces marxianus ATCC 16045. Upotrijebljeni su maseni udjeli organskih otapala u acetatnom puferu od 25 do 70 %, te je utvrđeno da maseni udjeli otapala nije bitno utjecao na značajke enzima, Optimalna je temperatura za aktivnost slobodnog enzima bila 55 °C pri svim udjelima otapala, a za imobilizirani enzim 55 °C uz dodataka 70 % butilnog acetata, te u rasponu od 50 do 60 °C uz dodatak 25 i 50 % otapala. Utvrđena je optimalna pH-vrijednost od 4,8 za slobodni, te 4,4 za imobilizirani enzim. Stabilnost imobiliziranog enzima bila je trostruko veća pri 50 °C i pH=4,8, pri svim udjelima otapala. Određeni su kinetički parametri primjenom dijagrama Lineweaver-Burk, te utvrđene ove vrijednosti za slobodni enzim: vmax od 12,5 U/mL pri 25 %, 58,5 U/mL pri 50 % i 37,6 U/mL pri 70 % otapala, te Km od 17,5 mM pri 25 %, 280,7 mM pri 50 %, te 210,4 mM pri 70 % otapala. Vrijednosti za imobilizirani enzim iznosile su: vmax od 38,9 U/mL pri 25 %, 59,5 U/mL pri 50 % i 72,5 U/mL pri 70 % otapala, a Km od 3,1 mM pri 25 %, 5,4 mM pri 50 % i 14,0 mM pri 70 % butilnog acetata

An empirical evaluation of imputation accuracy for association statistics reveals increased type-I error rates in genome-wide associations

<p>Abstract</p> <p>Background</p> <p>Genome wide association studies (GWAS) are becoming the approach of choice to identify genetic determinants of complex phenotypes and common diseases. The astonishing amount of generated data and the use of distinct genotyping platforms with variable genomic coverage are still analytical challenges. Imputation algorithms combine directly genotyped markers information with haplotypic structure for the population of interest for the inference of a badly genotyped or missing marker and are considered a near zero cost approach to allow the comparison and combination of data generated in different studies. Several reports stated that imputed markers have an overall acceptable accuracy but no published report has performed a pair wise comparison of imputed and empiric association statistics of a complete set of GWAS markers.</p> <p>Results</p> <p>In this report we identified a total of 73 imputed markers that yielded a nominally statistically significant association at <it>P </it>< 10 ^-5for type 2 Diabetes Mellitus and compared them with results obtained based on empirical allelic frequencies. Interestingly, despite their overall high correlation, association statistics based on imputed frequencies were discordant in 35 of the 73 (47%) associated markers, considerably inflating the type I error rate of imputed markers. We comprehensively tested several quality thresholds, the haplotypic structure underlying imputed markers and the use of flanking markers as predictors of inaccurate association statistics derived from imputed markers.</p> <p>Conclusions</p> <p>Our results suggest that association statistics from imputed markers showing specific MAF (Minor Allele Frequencies) range, located in weak linkage disequilibrium blocks or strongly deviating from local patterns of association are prone to have inflated false positive association signals. The present study highlights the potential of imputation procedures and proposes simple procedures for selecting the best imputed markers for follow-up genotyping studies.</p