University of Lisbon

About: University of Lisbon is a education organization based out in Lisbon, Lisboa, Portugal. It is known for research contribution in the topics: Population & Context (language use). The organization has 19122 authors who have published 48503 publications receiving 1102623 citations. The organization is also known as: Universidade de Lisboa & Lisbon University.

Characterization of the structure, dynamics, and productivity of mixed-species stands: review and perspectives

Abstract: The growth and yield of mixed-species stands has become an important topic of research since there are certain advantages of this type of forest as regards functions and services. However, the concepts and methods used to characterize mixed stands need to be understood, as well as harmonized and standardized. In this review we have compiled a set of measures, indices, and methods at stand level to characterize the structure, dynamics, and productivity of mixed stands, and we discuss the pros and cons of their application in growth and yield studies. Parameters for the characterization of mixed stand structure such as stand density, species composition, horizontal (intermingling) and vertical tree distribution pattern, tree size distribution, and age composition are described, detailing the potential as well as the constraints of these parameters for understanding resource capture, use, and efficiency in mixed stands. Furthermore, a set of stand-level parameters was evaluated to characterize the dynamics of mixed stands, e.g. height growth and space partitioning, self- and alien-thinning, and growth partitioning among trees. The deviations and changes in the behaviour of the analysed parameters in comparison with pure stand conditions due to inter-specific interactions are of particular interest. As regards stand productivity, we reviewed site productivity indices, the growth–density relationship in mixed stands as well as methods to compare productivity in mixed versus monospecific stands. Finally, we discuss the main problems associated with the methodology such as up-scaling from tree to stand level as well as the relevance of standardized measures and methods for improving forest growth and yield research in mixed stands. The main challenges are also outlined, especially the need for qualitatively sound data.

Caffeine intake and dementia: systematic review and meta-analysis.

Abstract: A recent meta-analysis of 4 studies published up to January 2004 suggests a negative association between coffee consumption and Alzheimer's disease, despite important heterogeneity in methods and results. Several epidemiological studies on this issue have been published since then, warranting an update of the insights on this topic. We conducted a systematic review and meta-analysis of published studies quantifying the relation between caffeine intake and cognitive decline or dementia. Data sources searched included Medline, LILACS, Scopus, Web of Science and reference lists, up to September 2009. Cohort and case-control studies were included. Three independent reviewers selected the studies and extracted the data on to standardized forms. Nine cohort and two case-control studies were included. Quantitative data synthesis of the most precise estimates from each study was accomplished through random effects meta-analysis. Heterogeneity was quantified using the I2 statistic. The outcomes of the studies considered for meta-analysis were Alzheimer's disease in four studies, dementia or cognitive impairment in two studies, and cognitive decline in three studies. The summary relative risk (RR) for the association between caffeine intake and different measures of cognitive impairment/decline was 0.84 [95% Confidence Interval (95% CI): 0.72-0.99; I2=42.6%]. When considering only the cohort studies, the summary RR was 0.93 (95% CI: 0.83-1.04, I2= 0.0%), and 0.77 (95% CI: 0.63-0.95, I2= 34.7%), if the most influential study was excluded. This systematic review and meta-analysis found a trend towards a protective effect of caffeine, but the large methodological heterogeneity across a still limited number of epidemiological studies precludes robust and definite statements on this topic. and definite statements on this topic.

Measurement of the distributions of event-by-event flow harmonics in lead-lead collisions at √SNN = 2.76 TeV with the ATLAS detector at the LHC

Abstract: The distributions of event-by-event harmonic flow coefficients v (n) for n = 2- 4 are measured in = 2.76 TeV Pb + Pb collisions using the ATLAS detector at the LHC. The measurements are performed u ...

Mind the Microgap in Iridescent Cellulose Nanocrystal Films.

Abstract: A new photonic structure is produced from cellulose nanocrystal iridescent films reflecting both right and left circularly polarized light. Micrometer-scale planar gaps perpendicular to the films' cross-section between two different left-handed films' cholesteric domains are impregnated with a nematic liquid crystal. This photonic feature is reversibly tuned by the application of an electric field or a temperature variation.

The Spitzer Extragalactic Representative Volume Survey (SERVS): Survey Definition and Goals

Abstract: We present the Spitzer Extragalactic Representative Volume Survey (SERVS), an 18 square degrees medium-deep survey at 3.6 and 4.5 microns with the post-cryogenic Spitzer Space Telescope to ~2 microJy (AB=23.1) depth of five highly observed astronomical fields (ELAIS-N1, ELAIS-S1, Lockman Hole, Chandra Deep Field South and XMM-LSS). SERVS is designed to enable the study of galaxy evolution as a function of environment from z~5 to the present day, and is the first extragalactic survey both large enough and deep enough to put rare objects such as luminous quasars and galaxy clusters at z>1 into their cosmological context. SERVS is designed to overlap with several key surveys at optical, near- through far-infrared, submillimeter and radio wavelengths to provide an unprecedented view of the formation and evolution of massive galaxies. In this paper, we discuss the SERVS survey design, the data processing flow from image reduction and mosaicing to catalogs, as well as coverage of ancillary data from other surveys in the SERVS fields. We also highlight a variety of early science results from the survey.