2,320 research outputs found

    Robustness of the O(NN) universality class

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    We calculate the critical exponents for Lorentz-violating O(NN) λϕ4\lambda\phi^{4} scalar field theories by using two independent methods. In the first situation we renormalize a massless theory by utilizing normalization conditions. An identical task is fulfilled in the second case in a massive version of the same theory, previously renormalized in the BPHZ method in four dimensions. We show that although the renormalization constants, the β\beta and anomalous dimensions acquire Lorentz-violating quantum corrections, the outcome for the critical exponents in both methods are identical and furthermore they are equal to their Lorentz-invariant counterparts. Finally we generalize the last two results for all loop levels and we provide symmetry arguments for justifying the latter

    Tracking the US Business Cycle With a Singular Spectrum Analysis

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    The monitoring of economic developments is an exercise of considerable importance forpolicy makers, namely, central banks and fiscal authorities as well as for other economic agents such as financial intermediaries, firms and households. However, the assessment of the business cycle is not an easy endeavor as the cyclical component is not an observable variable. In this paper we resort to singular spectrum analysis in order to disentangle the US GDP into several underlying components of interest. The business cycle indicator yielded through this method is shown to bear a resemblance with band-pass filtered output. As the end-of-sample behavior is typically a thorny issue in business cycle assessment, a real-time estimation exercise is here conducted to assess the reliability of the several filters. The obtained results suggest that the business cycle indicator proposed herein possesses a better revision performance than other filters commonly applied in the literature.

    Can Grazing Behaviour Support Innovations in Grassland Management?

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    Grazing is a fundamental process affecting grassland ecosystem dynamics and functioning. Its behavioural components comprise how animals search for feed, and gather and process plant tissues in different spatio-temporal scales of the grazing process. Nowadays, there is an increasing emphasis on grazing management and the role of the grazing animal on ecosystem services, concomitantly with a decreasing emphasis on grazing management generating animal production outputs. Grazing behaviour incorporates both approaches, which are not necessarily dichotomist. It would help in order to support innovation in grazing systems. However, it is unclear how the significant knowledge, developed in this research area since Agronomy and Ecology disciplines began to interact, have supported creativity in grazing science. It seems there is a current gap in this context, which was a major concern of researcher leaders like Harry Stobbs. This paper pays tribute to him, reviewing recent grazing behaviour research and prioritising those studies originating in the favourable tropics and subtropics. New evidence on how pasture structure limits forage intake in homogeneous and heterogeneous pastures is presented. Pasture management strategies designed to maximise bite mass and forage intake per unit grazing time are assumed to promote both animal production and landscape value. To conclude, a Brazilian case study (PISA) is briefly described to illustrate how grazing behaviour research can reach farmers and change their lives by using simple management strategies (take the best and leave the rest rule) supported by reductionist approaches applied in holistic frameworks

    Foraging Behaviour and Herbage Intake in the Favourable Tropics/Sub-Tropics

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    Herbage intake by animals grazing tropical/sub-tropical pastures is directly related to bite mass, as it is for those grazing temperate pastures. Where these swards have low proportions of stem and dead material (controlled swards), herbage intake follows a similar pattern to that of temperate pasture species, but leaf characteristics, such as lamina length play an important role and influence the short-term rate of intake. Sward structural characteristics and behavioural factors are relatively more important than nutritional factors in terms of herbage intake regulation. The feeding value of the herbage produced is potentially adequate to sustain high levels of beef cattle performance under controlled sward conditions, but relatively limited for dairy cows, since nutrient concentration in the forage is not optimal for high levels of daily milk yield. Sward targets for attaining production objectives are now a feasible management practice on tropical pastures and should be evaluated further

    Foraging Behaviour and Herbage Intake in the Favourable Tropics/Subtropics

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    Key points 1. Herbage intake by animals grazing tropical/sub-tropical pastures is directly related to bite mass, as it is for those grazing temperate pastures. 2. Where these swards have low proportions of stem and dead material (controlled swards), herbage intake follows a similar pattern to that of temperate pasture species, but leaf characteristics, such as lamina length play an important role and influence the short-term rate of intake. 3. Sward structural characteristics and behavioural factors are relatively more important than nutritional factors in terms of herbage intake regulation. The feeding value of the herbage produced is potentially adequate to sustain high levels of beef cattle performance under controlled sward conditions, but relatively limited for dairy cows, since nutrient concentration in the forage is not optimal for high levels of daily milk yield. 4. Sward targets for attaining production objectives are now a feasible management practice on tropical pastures and should be evaluated further

    Enhancing traffic sampling scope and efficiency

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    Traffic Sampling is a crucial step towards scalable network measurements, enclosing manifold challenges. The wide variety of foreseeable sampling scenarios demands for a modular view of sampling components and features, grounded on a consistent architecture. Articulating the measurement scope, the required information model and the adequate sampling strategy is a major design issue for achieving an encompassing and efficient sampling solution. This is the main focus of the present work, where a layered architecture, a taxonomy of existing sampling techniques distinguishing their inner characteristics and a flexible framework able to combine these characteristics are introduced. In addition, a new multiadaptive technique proposal, based on linear prediction, allows to reduce the measurement overhead significantly, while assuring that traffic samples reflect the statistical behavior of the global traffic under analysis.Fundação para a Ciência e a Tecnologia (FCT

    Sporotrichoid cutaneous leishmaniasis: atypical form

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    Leishmaniasis comprises a heterogeneous and extensive group of infectious and non-contagious diseases caused by protozoa of the genus Leishmania spp. It is a disease considered endemic in 92 countries, with at least 1 million new cases of integumentary forms annually. Cutaneous leishmaniasis is endemic in the tropics and neotropics. It is often referred to as a group of diseases because of the varied spectrum of clinical manifestations, which range from small cutaneous nodules to gross mucosal tissue destruction. Cutaneous leishmaniasis can be caused by several Leishmania spp. and is transmitted to human beings and animals by sandflies. Despite its increasing worldwide incidence, because it is rarely fatal, cutaneous leishmaniasis has become one of the so-called neglected diseases, In endemic countries, diagnosis is often made clinically and, if possible, by microscopic examination of lesion biopsy smears to visually confirm leishmania parasites as the cause. Cutaneous leishmaniasis often presents as an ulcerated lesion, with raised, infiltrated edges, classically described as frame-like edges at the site of the mosquito bite. We report an uncommon case of a patient who presented with a lesion on the face, sporotrichoid in appearance, and thigh, which appeared simultaneously, of clinical lesions of cutaneous leishmaniasis, laboratory-confirmed and which showed excellent clinical evolution with the use of liposomal amphotericin B

    K-means clustering combined with principal component analysis for material profiling in automotive supply chains

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    At a time where available data is rapidly increasing in both volume and variety, descrip- tive Data Mining (DM) can be an important tool to support meaningful decision-making processes in dynamic Supply Chain (SC) contexts. Up until now, however, scarce attention has been given to the application of DM techniques in the field of inventory management. Here, we take advantage of descriptive DM to detect and grasp important patterns among several features that coexist in a real-world automotive electronics SC. Concretely, Principal Component Analysis (PCA) is employed to analyze and understand the interrelations between ten quantitative and dependent variables in a multi-item/multi-supplier environment. Afterwards, the principal component scores are character- ized via a K-means clustering, allowing us to classify the samples into four clusters and to derive di↵erent profiles for the multiple inventory items. This work provides evidence that descriptive DM contributes to find interesting feature-patterns, resulting in the identification of important risk profiles that may e↵ectively leverage inventory management for superior performance.This work has been supported by FCT - Fundacao para a Ciencia e Tecnologia within the R&D Units Project Scope: UIDB/00319/2020. The authors want to extend grateful thanks to the editors and reviewers, whose comments have greatly improved the quality of the paper
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