A Fast Splitting Method for efficient Split Bregman Iterations

In this paper we propose a new fast splitting algorithm to solve the Weighted Split Bregman minimization problem in the backward step of an accelerated Forward-Backward algorithm. Beside proving the convergence of the method, numerical tests, carried out on different imaging applications, prove the accuracy and computational efficiency of the proposed algorithm

Drivers of adaptation to climate change in vulnerable farming communities: a micro analysis of rice farmers in Ndop, Cameroon

Farmers in developing economies often struggle to adapt to climate change and their decisions to adapt usually hinges on perception and prevailing socio-economic factors. This study examines factors controlling farmers’ decision to adapt to climate change and evaluate the impact of such decisions on farm output. Using primary data from 138 rice farming households in Ndop-Cameroon, we employ the probit model with endogenous switching regression to investigate the impact of the farmers’ adaptation decisions on output. The results indicate that access to credits, other incomes, farmers’ age, extension services and farmer groupings form key factors that significantly affects farmers’ decision to adapt to climate change. Strategic implementation of adaptive measures, significantly increased average output of adapters by 49%. Building resilience against climate change and ensuring food security, therefore requires stakeholders to take into account existing management strategies and the underlying factors influencing these. This study suggests the crucial need for institutional advancement and policy changes towards credit accessibility for rice farmers. More local farmers’ associations should be created and extension services improved to enhance effective adaptation and farmers’ vulnerability

A variational approach to Gibbs artifacts removal in MRI

Gibbs ringing is a feature of MR images caused by the finite sampling of the acquisition space (k-space). It manifests itself with ringing patterns around sharp edges which become increasingly significant for low-resolution acquisitions. In this paper, we model the Gibbs artefact removal as a constrained variational problem where the data discrepancy, represented in denoising and convolutive form, is balanced to sparsity-promoting regularization functions such as Total Variation, Total Generalized Variation and L1 norm of the Wavelet transform. The efficacy of such models is evaluated by running a set of numerical experiments both on synthetic data and real acquisitions of brain images. The Total Generalized Variation penalty coupled with the convolutive data discrepancy term yields, in general, the best results both on synthetic and real data

Uniform Penalty inversion of two-dimensional NMR Relaxation data

The inversion of two-dimensional NMR data is an ill-posed problem related to the numerical computation of the inverse Laplace transform. In this paper we present the 2DUPEN algorithm that extends the Uniform Penalty (UPEN) algorithm [Borgia, Brown, Fantazzini, {\em Journal of Magnetic Resonance}, 1998] to two-dimensional data. The UPEN algorithm, defined for the inversion of one-dimensional NMR relaxation data, uses Tikhonov-like regularization and optionally non-negativity constraints in order to implement locally adapted regularization. In this paper, we analyze the regularization properties of this approach. Moreover, we extend the one-dimensional UPEN algorithm to the two-dimensional case and present an efficient implementation based on the Newton Projection method. Without any a-priori information on the noise norm, 2DUPEN automatically computes the locally adapted regularization parameters and the distribution of the unknown NMR parameters by using variable smoothing. Results of numerical experiments on simulated and real data are presented in order to illustrate the potential of the proposed method in reconstructing peaks and flat regions with the same accuracy

Explicit exactly energy-conserving methods for Hamiltonian systems

For Hamiltonian systems, simulation algorithms that exactly conserve numerical energy or pseudo-energy have seen extensive investigation. Most available methods either require the iterative solution of nonlinear algebraic equations at each time step, or are explicit, but where the exact conservation property depends on the exact evaluation of an integral in continuous time. Under further restrictions, namely that the potential energy contribution to the Hamiltonian is non-negative, newer techniques based on invariant energy quadratisation allow for exact numerical energy conservation and yield linearly implicit updates, requiring only the solution of a linear system at each time step. In this article, it is shown that, for a general class of Hamiltonian systems, and under the non-negativity condition on potential energy, it is possible to arrive at a fully explicit method that exactly conserves numerical energy. Furthermore, such methods are unconditionally stable, and are of comparable computational cost to the very simplest integration methods (such as Störmer-Verlet). A variant of this scheme leading to a conditionally-stable method is also presented, and follows from a splitting of the potential energy. Various numerical results are presented, in the case of the classic test problem of Fermi, Pasta and Ulam and for nonlinear systems of partial differential equations, including those describing high amplitude vibration of strings and plates

Acute myeloid leukemia in infants: biology and treatment

Children aged 0-2 years (i.e., infants) with acute myeloid leukemia (AML) are a peculiar subgroup of patients in the childhood AML scenario. They present with distinctive biological and clinical characteristics, including a high prevalence of prognostically unfavorable risk factors and an increased susceptibility to therapy-related toxicity. Remarkable improvements have been achieved over the last two decades in the treatment of these patients and their outcome is becoming superimposable to that of the older age groups. In this review, we will focus on peculiarities of this young subgroup of children with AML, describing their clinical presentation, the biology of disease, and factors influencing outcome. Treatment results and toxicity data reported by major collaborative groups are also summarized and compared

MUPen2DTool: A new Matlab Tool for 2D Nuclear Magnetic Resonance relaxation data inversion

A great variety of applications requires to process two-dimensional NMR (2DNMR) data to obtain information about the materials properties. In order to face the increasing request for software to easily process 2DNMR data, in (Bortolotti et al. (2019) [1]), the authors released Upen2dTool, an open source MATLAB software tool implementing nonnegatively constrained uniform penalty locally adapted norm-based regularization for 2DNMR data inversion. This paper presents MUPen2DTool a new open-source MATLAB software tool implementing an unconstrained multipenalty regularization method based on and norms. The new software MUPen2DTool outperforms Upen2dTool since the implemented uniform multipenalty method allows to compute very accurate 2DNMR data inversion at reduced computational cost. By means of MUPen2DTool, the user can choose among several types of NMR experiments, and the free software provides codes that can be used and extended easily. Furthermore, a MATLAB interface makes it easier to include users own data. The practical use is demonstrated in the reported examples of both synthetic and real NMR data

The Role of Nutrition in Primary and Secondary Prevention of Cardiovascular Damage in Childhood Cancer Survivors

Innovative therapeutic strategies in childhood cancer led to a significant reduction in cancer-related mortality. Cancer survivors are a growing fragile population, at risk of long-term side effects of cancer treatments, thus requiring customized clinical attention. Antineoplastic drugs have a wide toxicity profile that can limit their clinical usage and spoil patients' life, even years after the end of treatment. The cardiovascular system is a well-known target of antineoplastic treatments, including anthracyclines, chest radiotherapy and new molecules, such as tyrosine kinase inhibitors. We investigated nutritional changes in children with cancer from the diagnosis to the end of treatment and dietary habits in cancer survivors. At diagnosis, children with cancer may present variable degrees of malnutrition, potentially affecting drug tolerability and prognosis. During cancer treatment, the usage of corticosteroids can lead to rapid weight gain, exposing children to overweight and obesity. Moreover, dietary habits and lifestyle often dramatically change in cancer survivors, who acquire sedentary behavior and weak adherence to dietary guidelines. Furthermore, we speculated on the role of nutrition in the primary prevention of cardiac damage, investigating the potential cardioprotective role of diet-derived compounds with antioxidative properties. Finally, we summarized practical advice to improve the dietary habits of cancer survivors and their families

Silicon (Si) biochar for the mitigation of arsenic (As) bioaccumulation in spinach (Spinacia oleracean) and improvement in the plant growth

In many parts of the world, growing crops on polluted soils often leads to elevated levels of pollutants in plant tissues. Minimizing the transfer of these pollutants into edible plant tissues while improving plant growth and productivity is a major area of research. In this study, we investigated the efficiency of silicon-modified biochar in reducing the uptake of As(III) in spinach (Spinacia oleracean) while simultaneously increasing the plant biomass. Unmodified biochars (uBC) and silicon-modified biochars (SiBC) were prepared from bamboo at 300 and 600 °C and characterized by Scanning Electron Microscopy with Energy Dispersive X-ray (SEM EDX), Fourier Transform Infrared Spectrometry (FTIR), X-ray Photoelectron Spectrometry (XPS), and X-ray Diffraction analysis (XRD). The bioaccumulation of As(III) in the edible part of spinach significantly decreased by 33.8 and 37.7% following the amendment of, respectively, 2% and 5% SiBC in soil. Biochar amendment increased the concentration of As(III) in pore water by 64.4% as a result of increased soil pH from 6.83 ± 0.4 to 8.01 ± 0.1 and dissolved organic carbon (DOC) from 7.02 ± 3.7 to 22.58 ± 3.7 g kg−1. However, the uptake of As(III) into spinach was prevented by silicon, which was preferentially transported to the plant through the same transport pathway as As(III). Dry biomass yield in spinach also significantly increased by 67.7% and strongly correlated (R2 = 0.97) with CaCl2 extractable Si in the plant. The results highlighted the effectiveness of SiBC in reducing the toxic effects of As in the environment and overall dietary exposure to the pollutant. The slow release of Si from biochars (<48.42%) compared to soil (87.39%) also suggested that SiBC can be efficient sources of Si fertilization for annual crops which can significantly reduce the increasing demand for Si fertilizers and their sustainable use in the environment

Changes in Physicochemical Properties of Biochar after Addition to Soil

It is recognized that biochar undergoes changes when it is applied to soils. However, the mechanisms of biochar alterations are not fully understood yet. To this purpose, the present study is designed to investigate the transformations in the soil of two different biochars obtained from pyrolysis of fir-wood pellets. The production of the biochars differed for the dry and wet quenching procedures used to terminate the pyrolysis. Both biochars were applied to clay soil (26% sand, 6% silt, and 68% clay) placed into lysimeters. After water saturation and 15 days of equilibration, seeds of watercress (Lepidium sativum) were cultivated. After a further 7 weeks, the biochars were manually separated from the systems. A total of four samples were collected. They were analyzed for chemical–physical characteristics by using an innovative technique referred to as fast field cycling nuclear magnetic resonance relaxometry. The results showed that the dry-quenching produced a material that was mainly chemically altered after application to soil compared to the biochar obtained by the wet-quenching. Indeed, the latter was both chemically and physically modified. In particular, results showed that water was better retained in the soil treated with the dry-quenched material. Consequently, we may suggest that crop productivity and environmental remediation may be modulated by applying either the dry-quenched or the wet-quenched biochar