24,584 research outputs found
Resilience and regime shifts in a marine biodiversity hotspot
Complex natural systems, spanning from individuals and populations to ecosystems and socialecological systems, often exhibit abrupt reorganizations in response to changing stressors, known as regime shifts or critical transitions. Theory suggests that such systems feature folded stability landscapes with fluctuating resilience, fold-bifurcations, and alternate basins of attraction. However, the implementation of such features to elucidate response mechanisms in an empirical context is scarce, due to the lack of generic approaches to quantify resilience dynamics in individual natural systems. Here, we introduce an Integrated Resilience Assessment (IRA) framework: a three-step analytical process to assess resilience and construct stability landscapes of empirical systems. The
proposed framework involves a multivariate analysis to estimate holistic system indicator variables, non-additive modelling to estimate alternate attractors, and a quantitative resilience assessment to scale stability landscapes. We implement this framework to investigate the temporal development of the Mediterranean marine communities in response to sea warming during 1985–2013, using fisheries landings data. Our analysis revealed a nonlinear tropicalisation of the Mediterranean Sea, expressed as abrupt shifts to regimes dominated by thermophilic species. The approach exemplified here for the Mediterranean Sea, revealing previously unknown resilience dynamics driven by climate forcing, can elucidate resilience and shifts in other complex systems
Computable randomness is about more than probabilities
We introduce a notion of computable randomness for infinite sequences that
generalises the classical version in two important ways. First, our definition
of computable randomness is associated with imprecise probability models, in
the sense that we consider lower expectations (or sets of probabilities)
instead of classical 'precise' probabilities. Secondly, instead of binary
sequences, we consider sequences whose elements take values in some finite
sample space. Interestingly, we find that every sequence is computably random
with respect to at least one lower expectation, and that lower expectations
that are more informative have fewer computably random sequences. This leads to
the intriguing question whether every sequence is computably random with
respect to a unique most informative lower expectation. We study this question
in some detail and provide a partial answer
Asphyxia neonatorum - assessment of the infant at birth
Asphyxia neonatorum is defined as failure of a newborn infant to establish sustained respiration after its complete delivery. In 206 asphyxiated infants reviewed, details of the Apgar scores, time to sustained respiration and resuscitation required, were documented. The value of each of these observations, as well as that of the heart rate and acid-base status after birth, is assessed. From the findings definite recommendations for the routine assessment of the infant at birth are made.S. Afr. Med. J., 48, 2139 (1974)
The mapping class group and the Meyer function for plane curves
For each d>=2, the mapping class group for plane curves of degree d will be
defined and it is proved that there exists uniquely the Meyer function on this
group. In the case of d=4, using our Meyer function, we can define the local
signature for 4-dimensional fiber spaces whose general fibers are
non-hyperelliptic compact Riemann surfaces of genus 3. Some computations of our
local signature will be given.Comment: 24 pages, typo adde
Comparative In Vitro Toxicity Of A Graphene Oxide-silver Nanocomposite And The Pristine Counterparts Toward Macrophages
Conselho Nacional de Desenvolvimento CientÃfico e Tecnológico (CNPq)Graphene oxide (GO) is a highly oxidized graphene form with oxygen functional groups on its surface. GO is an excellent platform to support and stabilize silver nanoparticles (AgNP), which gives rise to the graphene oxide-silver nanoparticle (GOAg) nanocomposite. Understanding how this nanocomposite interacts with cells is a toxicological challenge of great importance for future biomedical applications, and macrophage cells can provide information concerning the biocompatibility of these nanomaterials. The cytotoxicity of the GOAg nanocomposite, pristine GO, and pristine AgNP was compared toward two representative murine macrophages: a tumoral lineage (J774) and peritoneal macrophages collected from Balb/c mouse. The production of reactive oxygen species (ROS) by J774 macrophages was also monitored. We investigated the internalization of nanomaterials by transmission electron microscopy (TEM). The quantification of internalized silver was carried out by inductively coupled plasma mass spectrometry (ICP-MS). Nanomaterial stability in the cell media was investigated overtime by visual observation, inductively coupled plasma optical emission spectrometry (ICP OES), and dynamic light scattering (DLS). Results: The GOAg nanocomposite was more toxic than pristine GO and pristine AgNP for both macrophages, and it significantly induced more ROS production compared to pristine AgNP. TEM analysis showed that GOAg was internalized by tumoral J774 macrophages. However, macrophages internalized approximately 60 % less GOAg than did pristine AgNP. The images also showed the degradation of nanocomposite inside cells. Conclusions: Although the GOAg nanocomposite was less internalized by the macrophage cells, it was more toxic than the pristine counterparts and induced remarkable oxidative stress. Our findings strongly reveal a synergistic toxicity effect of the GOAg nanocomposite. The toxicity and fate of nanocomposites in cells are some of the major concerns in the development of novel biocompatible materials and must be carefully evaluated.14National Council for Technological and Scientific Development (CNPq) [140560/2014-9]Laboratory of Synthesis of Nanostructures and Interaction with Biosystems (NanoBioss)Brazilian Nanotoxicology Network-CigenanotoxNational Institute of Science, Technology and Innovation in Complex Functional Materials (INOMAT/INCT)Conselho Nacional de Desenvolvimento CientÃfico e Tecnológico (CNPq
Neutrophil gelatinase-associated lipocalin as an early indicator for postoperative renal failure
Two different methods for kinematic analysis of head movements relating to eye-head coordination in infants
BACKGROUND: Kinematic analysis is a method for quantitative assessment applied in different fields of study. In the field of motor development, this analysis may promote better understanding of the acquisition and development of motor skills. OBJECTIVE: To develop and compare two experimental set-ups for kinematic analysis of head movements relating to eye-head coordination (EHC) in infants. METHODS: Two experimental set-ups (A and B) were tested. They differed from each other regarding the numbers and locations of the cameras, and regarding the volume of the calibration system. RESULTS: The accuracy of the two experimental set-ups was 2.47mm, thus indicating that both can provide realistic reconstructions of the movement. The three cameras used in set-up B made it possible to view the full range of motion with at least one of the cameras. This led to improvement of the qualitative analysis and reduction of the time taken to process quantitative data, which was 33% shorter than seen with set-up A. In addition, set-up B presented a better cost-benefit relationship. CONCLUSIONS: Although both set-ups were adequate for kinematic analysis of head movements relating to EHC in infants, set-up B is more advantageous. The methodology for set-up B can be used in studies investigating head movements in either typical or atypical infants. The results from such studies could be used to complement assessments on at-risk infants and consequently could assist in implementing early interventions.CONTEXTUALIZAÇÃO: A análise cinemática é um método de avaliação quantitativa empregada em diferentes áreas de estudo. Na área do desenvolvimento motor, essa análise pode proporcionar uma melhor compreensão da aquisição e do desenvolvimento das habilidades motoras. OBJETIVOS: Desenvolver e comparar dois arranjos experimentais para análise cinemática dos movimentos de cabeça durante a coordenação viso-cefálica (CVC) em lactentes. MATERIAIS E MÉTODOS: Foram testados dois arranjos experimentais (A e B) que diferiam quanto ao número e posicionamento das câmeras, bem como quanto ao volume do sistema de calibração. RESULTADOS: A acurácia dos dois arranjos experimentais foi de 2,47mm, indicando que ambos podem fornecer uma reconstrução verossÃmil do movimento. As três câmeras usadas no arranjo B favoreceram a visualização de toda a amplitude do movimento por pelo menos uma das câmeras. Isso levou à melhora da análise qualitativa e à redução do tempo de processamento dos dados quantitativos, reduzindo-o em 33% quando comparado ao arranjo A. Além disso, o arranjo B apresentou melhor relação custo-benefÃcio. CONCLUSÕES: Ambos os arranjos são adequados para a análise cinemática dos movimentos de cabeça durante a CVC de lactentes, entretanto, o arranjo B é mais vantajoso. A metodologia do arranjo B pode ser empregada em estudos que investigam o movimento de cabeça de lactentes, sejam eles tÃpicos ou atÃpicos. Os resultados de tais estudos poderão ser empregados para complementar a avaliação de lactentes de risco e, conseqüentemente, auxiliar na intervenção precoce destes.Universidade Federal de São Carlos Departamento de Fisioterapia Setor de NeuropediatriaUniversidade Federal de São Paulo (UNIFESP) Departamento de Ciências da SaúdeUniversidade Estadual de Campinas Faculdade de Educação FÃsica Laboratório de Instrumentação BiomecânicaUNIFESP, Depto. de Ciências da SaúdeSciEL
A New Approach for Modelling Chromospheric Evaporation in Response to Enhanced Coronal Heating: 1 The Method
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