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Abstract: We study the periodic solutions of the generalized Abel equation , where are distinct integers, , and are -periodic analytic functions such that are -periodic positive even functions. When we prove that the equation has no non-trivial (different from zero) limit cycle for any value of the parameters . When we obtain under additional conditions the existence of non-trivial limit cycles. In particular, we obtain limit cycles not detected by Abelian integrals. [Copyright &y& Elsevier]

Abstract: In this paper we study the number of limit cycles of two families of cubic systems introduced in previous papers to model real phenomena. The first one is motivated by a model of star formation histories in giant spiral galaxies and the second one comes from a model of Volterra type. To prove our results we develop a new criterion on the non-existence of periodic orbits and we extend a well-known criterion on the uniqueness of limit cycles due to Kuang and Freedman. Both results allow to reduce the problem to the control of the sign of certain functions that are treated by algebraic tools. Moreover, in both cases, we prove that when the limit cycles exist they are non-algebraic. [Copyright &y& Elsevier]

Abstract: For the family of scalar Abel-like equations , where , , , , , and , we characterize the existence of non-trivial limit cycles (periodic solutions that are isolated in the set of periodic solutions different from the trivial ) in terms of . [Copyright &y& Elsevier]

Abstract: In this work we focus on the configuration (location and stability) of simple critical points of polynomial differential equations of the form , . The case where all the critical points are of center type is studied in more detail finding several new center configurations. One of the main tools in our approach is the 1-dimensional Euler–Jacobi formula. [Copyright &y& Elsevier]

Abstract: In this article we give two criteria for bounding the number of non-contractible limit cycles of a family of differential systems on the cylinder. This family includes Abel equations as well as the polar expression of several types of planar polynomial systems given by the sum of three homogeneous vector fields. [Copyright &y& Elsevier]

The rotation of uniaxial ellipsoidal particles has provided the base for many studies of shape preferred orientations of mineral grains in a large variety of rock types. In this paper we present reports of a study of the evolution of a multiparticle system as a function of the elongation ratio of the particles and of the initial particle distribution. Our model reveals that both factors are important in controlling the acquisition of a stable orientation upon deformation. The more elongated particles (r=short axis/long axis≤0.5) will define a stable fabric in almost any situation of geologic interest (γ=shear deformation<10), but less elongated particles (r>0.5) can also be considered to have achieved a stable orientation depending on the total amount of shear experienced by the rock. However, in systems with the less elongated particles (r≥0.8) it is possible to find mean orientations that are perpendicular to the direction of shear, although the occurrence of such behavior constitutes only a minor fraction of the studied examples. In any case, it is suggested that a systematic study of mineral fabrics in samples from the same rock can yield enough information to evaluate whether the mean shape preferred orientation of the minerals is parallel to flow direction. [Copyright &y& Elsevier]

Abstract: One of the most important challenges that confronts less-than-truckload carriers serving many-to-many distribution networks consists of determining how to consolidate flows of small shipments. The objective is to determine a route for each origin–destination pair that minimizes the cost while still guaranteeing a certain level of service. This research studies different aspects of the problem and provides a metaheuristic algorithm (based on Ant Colony Optimization techniques) capable of solving real-life problems in a reasonable computational time. The viability of the approach has been tested with a real case in Spain and encouraging results have been obtained. [Copyright &y& Elsevier]

Abstract: One of the main problems dealing with iterative methods for solving polynomial systemsis the initialization of the iteration. This paper provides an algorithm to initialize the search of solutions of polynomial systems. [Copyright &y& Elsevier]

Current research on the circular economy (CE) reveals that, while the concept and its application have been extensively explored as shown in several case studies, the definition of tools and criteria measuring "circularity" of products, companies or regions are not well-defined. Therefore, indicators for measuring the different levels of a CE (micro, meso, and macro) should be a high priority for stakeholders (governments, companies, NGOs, civil society, etc.) in order to track progress on CE initiatives. However, the increasing interest on CE has caused a still open debate on the conceptualization of CE which hampers the creation of indicators based on a common conceptual framework. As a result, the absence of standard indicators to track progress on circularity is leading to contradiction and misunderstanding, which represents a challenge to the implementation of CE strategies. Thus, this study tries to address this gap by advancing a set of indicators adapted from existing indicators that guarantees simplicity and effectiveness, closely based on indicators proposed by government bodies. This research carried out an exploratory study to formulate the indicators requirements based on literature, refined through experts' opinion and then they were tested in Spanish companies located in the Basque Country region through an empirical work to assess this theory. A mix of research methods (e.g. semi-structured interviews and surveys) were used to seek applicability of CE indicators for organisations. The study showed that the proposed indicators currently used for assessing the CE at the macro level were applicable at the micro level based on companies' responses. This fact demonstrated that the indicators serve the purpose of being applicable to companies regardless of the type of economic activity they were in. Also, it shows that indicators used to monitor progress on CE at the macro level can be translated to the micro level. Consequently, it is recommended that the set of CE indicators focused on the methodology proposed in this study should be used across different industrial sectors in order to observe performance in companies to facilitate the transition to a CE model. • The main objective of this study was to advance the indicators currently available. • The indicators were tested in companies to prove their suitability for circular economy assessment. • The proposed indicators collected the data in already existing statistics records. • These indicators might help companies to track their actions and strategies in circular economy. [ABSTRACT FROM AUTHOR]

Abstract: In this work we present the energy and spatial resolutions we have obtained for a detector based on a monolithic LYSO crystal coupled to an array of 256 SiPMs. Two crystal configurations of the same trapezoidal shape have been tried. In one approach all surfaces were black painted but the exit one facing the photosensor array which was polished. The other approach included a retroreflector (RR) layer coupled to the entrance face of the crystal powering the amount of transmitted light to the photosensors. Two coupling media between the scintillator and the SiPM array were used, namely direct coupling by means of optical grease and coupling through an array of light guides. Since the same operational voltage was supplied to the entire array, it was needed to equalize their gains before feeding their signals to the Data Acquisition system. Such a job was performed by means of 4 scalable Application Specific Circuits (ASICs). An energy resolution of about 24.4% has been achieved for the direct coupling with the RR layer together with a spatial resolution of approximately 2.9mm at the detector center. With the light guides coupling the effects of image compression at the edges are significantly minimized, but worsening the energy resolution to about 33.1% with a spatial resolution nearing 4mm at the detector center. [Copyright &y& Elsevier]

Abstract: In this work we present a method to efficiently collect scintillation light when using monolithic scintillator crystals. The acceptance angle of the scintillation light has been reduced by means of optical devices reducing the border effect which typically affects continuous crystals. We have applied this procedure on gamma detectors for PET systems using both position sensitive PMTs and arrays of SiPMs. In the case of using SiPMs, this approach also helps to reduce the photosensor active area. We evaluated the method using PMTs with a variety of different crystals with thicknesses ranging from 10 to 24mm. We found that our design allows the use of crystal blocks with a thickness of up to 18mm without degrading the spatial resolution caused by edge effects and without a significant detriment to the energy resolution. These results were compared with simulated data. The first results of monolithic LYSO crystals coupled to an array of 256 SiPMs by means of individual optical light guides are also presented. [Copyright &y& Elsevier]

Abstract: In this work we present an innovative algorithm for the reconstruction of PET images based on the List-Mode (LM) technique which improves their spatial resolution compared to results obtained with current MLEM algorithms. This study appears as a part of a large project with the aim of improving diagnosis in early Alzheimer disease stages by means of a newly developed hybrid PET-MR insert. At the present, Alzheimer is the most relevant neurodegenerative disease and the best way to apply an effective treatment is its early diagnosis. The PET device will consist of several monolithic LYSO crystals coupled to SiPM detectors. Monolithic crystals can reduce scanner costs with the advantage to enable implementation of very small virtual pixels in their geometry. This is especially useful for LM reconstruction algorithms, since they do not need a pre-calculated system matrix. We have developed an LM algorithm which has been initially tested with a large aperture (186mm) breast PET system. Such an algorithm instead of using the common lines of response, incorporates a novel calculation of tubes of response. The new approach improves the volumetric spatial resolution about a factor 2 at the border of the field of view when compared with traditionally used MLEM algorithm. Moreover, it has also shown to decrease the image noise, thus increasing the image quality. [Copyright &y& Elsevier]

Abstract: In this paper we describe the overall design of a PET–MR system for head imaging within the framework of the DREAM Project as well as the first detector module tests. The PET system design consists of 4 rings of 16 detector modules each and it is expected to be integrated in a head dedicated radio frequency coil of an MR scanner. The PET modules are based on monolithic LYSO crystals coupled by means of optical devices to an array of 256 Silicon Photomultipliers. These types of crystals allow to preserve the scintillation light distribution and, thus, to recover the exact photon impact position with the proper characterization of such a distribution. Every module contains 4 Application Specific Integrated Circuits (ASICs) which return detailed information of several light statistical momenta. The preliminary tests carried out on this design and controlled by means of ASICs have shown promising results towards the suitability of hybrid PET–MR systems. [Copyright &y& Elsevier]

Background Obesity is a global epidemic that continues to increase in a great number of countries, and it has become a major public health problem in Spain. Unfortunately, the impact of obesity on survival in liver transplantation (LT) recipients is underestimated and controversial. The aim of this study was to determine if obesity is a risk factor for morbidity and mortality after LT. Methods In a retrospective cohort study of the records of 180 consecutive patients who had undergone to LT from 2007 to 2013, 11 obese patients with body mass index (BMI) >35 kg/m 2 were identified. Their data have been compared with recipients with BMI 20–25 kg/m 2 . Results There were no differences in demographic data, Child-Pugh score, Model for End-Stage Liver Disease score, or cause of liver failure. BMI >35 kg/m 2 recipients had a significantly higher rate of portal vein thrombosis before LT, compared with the BMI 20–25 kg/m 2 group (36.5% vs 13.9%; P = .041). There were also no differences in development of post-reperfusion syndrome. The groups were also comparable concerning morbidity rate after LT, stay in the intensive care unit, and global hospital stay. However, the mortality rate was significantly higher in the obese group compared with the nonobese group (72.7% vs 38.9%; P = .032). Conclusions The results of the study clearly demonstrate higher mortality rates in obese patients undergoing LT; thus, it is fair to consider obesity as a poor prognosis predictive factor concerning mortality rate. [ABSTRACT FROM AUTHOR]

Abstract: Introduction: Rapamycin (RAPA) is a powerful immunosuppressant that also acts as an antiproliferative, which, therefore, could be useful in the treatment and prevention of bronchiolitis obliterans (BOS) in lung transplant recipients. We sought to report our experiences with RAPA in lung transplant patients with BOS that has not responded to the administration of other drugs. Materials and methods: We performed a retrospective analysis of the clinical characteristics, pulmonary function, and complications among patients with BOS who received RAPA. Results: RAPA was administered to 11 patients, three single-lung transplant and eight bilateral lung transplant recipients, of whom five were women and six men, of mean age 48 years (26 to 65). The median posttransplant time to the initiation of RAPA for progressive BOS was 32 months (4 to 69) with a posttreatment follow-up of 15 months (3 to 34). RAPA was administered to all patients in association with a calcineurin inhibitor (tacrolimus in seven cases, and cyclosporine in four and steroids. Eight of the 11 patients (72%) with progressive deterioration of pulmonary function showed improved and/or stabilized FEV1 figures after introduction of RAPA. Eight patients developed adverse effects, which were possibly related to RAPA, leading to treatment withdrawal in two cases. The most frequent adverse effects were infections among 6 of the 12 cases, and myelosuppression in three. Conclusions: RAPA may be useful to stabilize or improve pulmonary function in patients with BOS. Nevertheless, it was necessary for patients to be closely monitored so that possible adverse effects, and especially infections, may be detected early. [Copyright &y& Elsevier]