466 research outputs found
Águas Subterrâneas em Cabo Verde - Qualidade da Água na Ilha de Santiago
Em Cabo Verde os recursos hídricos subterrâneos desempenham um papel fundamental, constituindo a
principal fonte de abastecimento de água para as populações de pequenos aglomerados urbanos.
O trabalho que se apresenta enquadra-se num estudo alargado de caracterização de águas subterrâneas; foi
efectuado nos seis concelhos da ilha de Santiago a maior do país, em captações do tipo poço, furo e galeria
destinadas ao abastecimento da população através de chafarizes e resulta de uma parceria entre o Instituto
Nacional de Gestão dos Recursos Hídricos de Cabo Verde (INGRH) e o Instituto Nacional de Saúde, Porto de
Portugal (INSA-Porto).
Com base nos dados obtidos, e no sentido de uma cooperação alargada, propõe-se a criação do
Observatório de Águas Subterrâneas nos Países Africanos de expressão Portuguesa
Neuroblastoma Perinatal – Um Desafio para o Neonatologista
O neuroblastoma é o tumor maligno mais frequente no período neonatal. O diagnóstico pré-natal tem aumentado devido à
qualidade da ecografia obstétrica, que permite a deteção de formações de pequenas dimensões nas glândulas suprarrenais.
Apresentam-se os casos clínicos de quatro recém‑nascidos com o diagnóstico de neuroblastoma perinatal. Dois recém-nascidos
apresentaram imagens quísticas pré-natais na suprarrenal, estavam assintomáticos ao nascimento e o diagnóstico foi sugerido
pela vigilância imagiológica. Outro recém-nascido não apresentava alterações nas ecografias pré-natais mas, ao nascer, era
evidente distensão abdominal com massa palpável, cuja avaliação imagiológica sugeriu neuroblastoma. No quarto recém-
-nascido, o diagnóstico de neuroblastoma foi evocado na gravidez. Estes últimos dois recém-nascidos faleceram após início
de terapêutica imediata cirúrgica e/ou quimioterapia. As imagens quísticas da suprarrenal no período perinatal constituem
um desafio diagnóstico, devendo ser sempre considerada a hipótese de neuroblastoma, mesmo quando o recém-nascido está
assintomático
Sulfadiazine-selective determination in aquaculture environment: Selective potentiometric transduction by neutral or charged ionophores
Solid-contact sensors for the selective screening of sulfadiazine (SDZ) in aquaculture waters are reported. Sensor surfaces were made from PVC membranes doped with tetraphenylporphyrin-manganese(III) chloride, α-cyclodextrin, β-cyclodextrin, or γ-cyclodextrin ionophores that were dispersed in plasticizer. Some membranes also presented a positive or a negatively charged additive. Phorphyrin-based sensors relied on a charged carrier mechanism. They exhibited a near-Nernstian response with slopes of 52 mV decade−1 and detection limits of 3.91 × 10−5 mol L−1. The addition of cationic lipophilic compounds to the membrane originated Nernstian behaviours, with slopes ranging 59.7–62.0 mV decade−1 and wider linear ranges. Cyclodextrin-based sensors acted as neutral carriers. In general, sensors with positively charged additives showed an improved potentiometric performance when compared to those without additive. Some SDZ selective membranes displayed higher slopes and extended linear concentration ranges with an increasing amount of additive (always <100% ionophore). The sensors were independent from the pH of test solutions within 2–7. The sensors displayed fast response, always <15 s. In general, a good discriminating ability was found in real sample environment. The sensors were successfully applied to the fast screening of SDZ in real waters samples from aquaculture fish farms. The method offered the advantages of simplicity, accuracy, and automation feasibility. The sensing membrane may contribute to the development of small devices allowing in locus measurements of sulfadiazine or parent-drugs
A mixture of coal wash and fly ash as a pavement substructure material
The reuse of waste materials in engineering projects has become the subject of many research efforts worldwide as it provides economical as well as environmental benefits. Coal wash (CW) and fly ash (FA) are example waste materials that can be used as alternative aggregates in transportation infrastructure projects, specifically as base and subbase materials in roads. Class C FA has been extensively used as a stabilizing material due to its hardening potential. However, Class F fly ash, a non-pozzolanic material when used alone, has not been considered in past research projects. In this study, Class F fly ash is mixed with coal wash as a void filler to enhance its compaction efficiency and produce a compact and well interlocked structure. A laboratory testing plan is performed to assess the geotechnical properties of the mixtures with 0%, 7%, 10% and 13% FA content and it includes compaction tests, unconfined compressive strength tests, California Bearing Ratio (CBR) tests, collapse potential tests and permeability tests. The mixture with 7% FA is selected as the optimum mixture and its potential for tensile cracking under service loads is further investigated using four-point bending tests. Also, the resilient modulus and permanent deformations of the mixture are evaluated under different dry-back conditions using multistage repeated load triaxial tests
Monte Carlo simulations of 2d hard core lattice gases
Monte Carlo simulations are used to study lattice gases of particles with
extended hard cores on a two dimensional square lattice. Exclusions of one and
up to five nearest neighbors (NN) are considered. These can be mapped onto hard
squares of varying side length, (in lattice units), tilted by some
angle with respect to the original lattice. In agreement with earlier studies,
the 1NN exclusion undergoes a continuous order-disorder transition in the Ising
universality class. Surprisingly, we find that the lattice gas with exclusions
of up to second nearest neighbors (2NN) also undergoes a continuous phase
transition in the Ising universality class, while the Landau-Lifshitz theory
predicts that this transition should be in the universality class of the XY
model with cubic anisotropy. The lattice gas of 3NN exclusions is found to
undergo a discontinuous order-disorder transition, in agreement with the
earlier transfer matrix calculations and the Landau-Lifshitz theory. On the
other hand, the gas of 4NN exclusions once again exhibits a continuous phase
transition in the Ising universality class -- contradicting the predictions of
the Landau-Lifshitz theory. Finally, the lattice gas of 5NN exclusions is found
to undergo a discontinuous phase transition.Comment: 13 pages, lots of figure
Heterogeneous contributions can jeopardize cooperation in the Public Goods Game
When studying social dilemma games, a crucial question arises regarding the
impact of general heterogeneity on cooperation, which has been shown to have
positive effects in numerous studies. Here, we demonstrate that heterogeneity
in the contribution value for the focal Public Goods Game can jeopardize
cooperation. We show that there is an optimal contribution value in the
homogeneous case that most benefits cooperation depending on the lattice. In a
heterogeneous scenario, where strategy and contribution coevolve, cooperators
making contributions higher than the optimal value end up harming those who
contribute lower. This effect is notably detrimental to cooperation in the
square lattice with von Neumann neighborhood, while it can have no impact in
others lattices. Furthermore, in parameter regions where a higher-contributing
cooperator cannot normally survive alone, the exploitation of lower value
contribution cooperators allows their survival, resembling a parasitic
behavior. To obtain these results, we employed various distributions for the
contribution values in the initial condition and conducted Monte Carlo
simulations
Cervical nodular fasciitis in a 10-year-old girl: a case report of a rare condition
Nodular fasciitis (NF) is a benign fibroblastic proliferation that usually involves superficial fascia in the subcutaneous tissue or muscle. The rapid growth, high cellularity and mitotic activity can simulate sarcoma. Thus, as clinical and morphologic characteristics are similar to those of malignant tumours, this entity is often misdiagnosed, with a few cases described in the literature. We present a case of nodular fasciitis involving the retropharynx and hypopharynx of a 10-year-old girl and discuss the importance of considering this rare diagnosis in different soft tissue masses.Keywords: excisional biopsy, histology, nodular fasciiti
Symbiotic behaviour in the Public Goods game with altruistic punishment
Finding ways to overcome the temptation to exploit one another is still a
challenge in behavioural sciences. In the framework of evolutionary game
theory, punishing strategies are frequently used to promote cooperation in
competitive environments. Here, we introduce altruistic punishers in the
spatial public goods game. This strategy acts as a cooperator in the absence of
defectors, otherwise it will punish all defectors in their vicinity while
bearing a cost to do so. We observe three distinct behaviours in our model: i)
in the absence of punishers, cooperators (who don't punish defectors) are
driven to extinction by defectors for most parameter values; ii) clusters of
punishers thrive by sharing the punishment costs when these are low iii) for
higher punishment costs, punishers, when alone, are subject to exploitation but
in the presence of cooperators can form a symbiotic spatial structure that
benefits both. This last observation is our main finding since neither
cooperation nor punishment alone can survive the defector strategy in this
parameter region and the specificity of the symbiotic spatial configuration
shows that lattice topology plays a central role in sustaining cooperation.
Results were obtained by means of Monte Carlo simulations on a square lattice
and subsequently confirmed by a pairwise comparison of different strategies'
payoffs in diverse group compositions, leading to a phase diagram of the
possible states
- …