18,919 research outputs found
Finite element approximation of the -Laplacian
We study a~priori estimates for the Dirichlet problem of the
-Laplacian,
We show that the gradients of the finite element approximation with zero
boundary data converges with rate if the exponent is
-H\"{o}lder continuous. The error of the gradients is measured in the
so-called quasi-norm, i.e. we measure the -error of
High-fidelity simulations of CdTe vapor deposition from a new bond-order potential-based molecular dynamics method
CdTe has been a special semiconductor for constructing the lowest-cost solar
cells and the CdTe-based Cd1-xZnxTe alloy has been the leading semiconductor
for radiation detection applications. The performance currently achieved for
the materials, however, is still far below the theoretical expectations. This
is because the property-limiting nanoscale defects that are easily formed
during the growth of CdTe crystals are difficult to explore in experiments.
Here we demonstrate the capability of a bond order potential-based molecular
dynamics method for predicting the crystalline growth of CdTe films during
vapor deposition simulations. Such a method may begin to enable defects
generated during vapor deposition of CdTe crystals to be accurately explored
Instability of reconstruction of the low CMB multipoles
We discuss the problem of the bias of the Internal Linear Combination (ILC)
CMB map and show that it is closely related to the coefficient of
cross-correlation K(l) of the true CMB and the foreground for each multipole l.
We present analysis of the cross-correlation for the WMAP ILC quadrupole and
octupole from the first (ILC(I)) and the third (ILC(III)) year data releases
and show that these correlations are about -0.52-0.6. Analysing 10^4 Monte
Carlo simulations of the random Gaussian CMB signals, we show that the
distribution function for the corresponding coefficient of the
cross-correlation has a polynomial shape P(K,l)\propto(1-K^2)^(l-1). We show
that the most probable value of the cross-correlation coefficient of the ILC
and foreground quadrupole has two extrema at K ~= +/-0.58$. Thus, the ILC(III)
quadrupole represents the most probable value of the coefficient K. We analyze
the problem of debiasing of the ILC CMB and pointed out that reconstruction of
the bias seems to be very problematic due to statistical uncertainties. In
addition, instability of the debiasing illuminates itself for the quadrupole
and octupole components through the flip-effect, when the even (l+m) modes can
be reconstructed with significant error. This error manifests itself as
opposite, in respect to the true sign of even low multipole modes, and leads to
significant changes of the coefficient of cross-correlation with the
foreground. We show that the CMB realizations, whose the sign of quadrupole
(2,0) component is negative (and the same, as for all the foregrounds), the
corresponding probability to get the positive sign after implementation of the
ILC method is about 40%.Comment: 11 pages, 5 figure
Discrepancies in Determinations of the Ginzburg-Landau Parameter
Long-standing discrepancies within determinations of the Ginzburg-Landau
parameter from supercritical field measurements on superconducting
microspheres are reexamined. The discrepancy in tin is shown to result from
differing methods of analyses, whereas the discrepancy in indium is a
consequence of significantly differing experimental results. The reanalyses
however confirms the lower determinations to within experimental
uncertainties.Comment: submitted to Phys. Rev.
Potencial fitorremediador de Spirodela polyrhiza em meio aquático contaminado por drenagem ácida de minas.
A contaminação de corpos hídricos por drenagem ácida de minas (DAM) resulta no aumento da concentração de elementos possivelmente tóxicos e consequente alteração na cadeia trófica. Portanto, devido à necessidade de tecnologias para remoção de substâncias potencialmente nocivas ao meio ambiente, a espécie vegetal Spirodela polyrhiza se apresenta como uma alternativa, devido à sua capacidade de absorver e acumular diversos elementos, essenciais ou não para o seu metabolismo. O objetivo deste trabalho foi avaliar a acumulação dos elementos Fe, Mn e As nos tecidos de S. polyrhiza. Foram realizados ensaios S. polyrhiza em casa de vegetação e aplicados sete tratamentos: I.DAM pH 2,5; 2.Água pH 2,5; 3.DAM pH 3,5; 4.Água pH 3,5; 5.DAM pH 4,5; 6.Água pH 4,5; 7.Controle. As maiores concentrações de Fe e As foram quantificadas nas plantas do tratamento 2, que acumularam 1,164 mg kg-1 e 39,929mg.kg-', respectivamente; e Mn, no tratamento 6, com 1,813 mg kg-I. Quanto menor o pH do meio, menor a matéria seca das plantas, com redução da biomassa de até 55%. As plantas submetidas ao tratamento 6 apresentaram desenvolvimento semelhante ao controle, e com acumulação significativa dos quatro elementos. Pode-se concluir que S. polyrhiza absorve diversos elementos simultaneamente em quantidades significativas
Exploratory Study on the Associations between Lifetime Post-Traumatic Stress Spectrum, Sleep, and Circadian Rhythm Parameters in Patients with Bipolar Disorder
The present study aimed at exploring whether lifetime post-traumatic stress spectrum symptoms are associated with chronotype in patients with bipolar disorder (BD). Moreover, we explored whether the chronotype can moderate the potential associations between lifetime post-traumatic stress spectrum symptoms and rest–activity circadian and sleep-related parameters. A total of 74 BD patients were administered the Trauma and Loss Spectrum Self-Report (TALS-SR) lifetime version for lifetime post-traumatic stress spectrum symptoms, the Pittsburgh Sleep Quality Index (PSQI) for self-reported sleep quality, and the Reduced Morningness–Eveningness Questionnaire (rMEQ) to discriminate evening chronotypes (ETs), neither chronotype (NT), and morning chronotype (MT). Actigraphic monitoring was used to objectively evaluate sleep and circadian parameters. Patients classified as ET reported significantly higher scores in the re-experiencing domain, as well as poorer sleep quality, lower sleep efficiency, increased wake after sleep onset, and delayed mid-sleep point compared with both NT and MT (p-value ≤ 0.05). Moreover, ET presented significantly higher scores in the TALS-SR maladaptive coping domain than NT and lower relative amplitude than MT (p-value ≤ 0.05). Moreover, higher TALS-SR total symptomatic domains scores were significantly correlated with poor self-reported sleep quality. Regression analyses showed that the PSQI score maintained the association with the TALS total symptomatic domains scores after adjusting for potentially confounding factors (age and sex) and that no interaction effect was observed between the chronotype and the PSQI. Conclusions: This exploratory study suggests that patients with BD classified as ET showed significantly higher lifetime post-traumatic stress spectrum symptoms and more disrupted sleep and circadian rhythmicity with respect to other chronotypes. Moreover, poorer self-reported sleep quality was significantly associated with lifetime post-traumatic stress spectrum symptoms. Further studies are required to confirm our results and to evaluate whether targeting sleep disturbances and eveningness can mitigate post-traumatic stress symptoms in BD
Correlation properties of the maps of the NVSS survey and WMAP ILC
In this paper we study one-dimensional sections of the maps of WMAP ILC and
of the NVSS survey on scale lengths of 0.75, 3, 4.5, and 6.75 degrees and
analyze the correlation properties of the sections. On these maps we identify
the domains where the absolute value of the correlation coefficient exceeds
0.5. The catalog of such domains is presented. It is shown that the number of
the domains agrees with the number of such domains on simulated maps and this
fact may be indicative of just statistical agreement of the arrangement of the
domains considered.Comment: 8 pages, 2 figure
Deep computer vision system for cocoa classification
Cocoa hybridisation generates new varieties which are resistant to several plant diseases, but has individual chemical characteristics that affect chocolate production. Image analysis is a useful method for visual discrimination of cocoa beans, while deep learning (DL) has emerged as the de facto technique for image processing. However, these algorithms require a large amount of data and careful tuning of hyperparameters. Since it is necessary to acquire a large number of images to encompass the wide range of agricultural products, in this paper, we compare a Deep Computer Vision System (DCVS) and a traditional Computer Vision System (CVS) to classify cocoa beans into different varieties. For DCVS, we used a Resnet18 and Resnet50 as backbone, while for CVS, we experimented traditional machine learning algorithms, Support Vector Machine (SVM), and Random Forest (RF). All the algorithms were selected since they provide good classification performance and their potential application for food classification A dataset with 1,239 samples was used to evaluate both systems. The best accuracy was 96.82% for DCVS (ResNet 18), compared to 85.71% obtained by the CVS using SVM. The essential handcrafted features were reported and discussed regarding their influence on cocoa bean classification. Class Activation Maps was applied to DCVS’s predictions, providing a meaningful visualisation of the most important regions of the images in the model
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