767 resultados para Piranha attacks
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Tese de doutoramento, História (Arte Património e Restauro), Universidade de Lisboa, Faculdade de Letras, 2014
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Here we review some of the most important aspects of recent work on Ragweed (Ambrosia) and birch (Betula) concerning: 1) sources, 2) trends & phenology and 3) dispersion and transformation. Sources: At Northern latitudes the birch fraction in forests usually exceeds 50% of all broadleaved trees and the abundance of birch decreases with latitude from 5%-20% in many mid-latitude regions and down to 0%-2% in more southern areas. Birches are also commonly found in small woodlands or planted as ornamental trees in urban areas. Ragweeds are herbaceous weed species that are associated with areas of disturbance. Ragweed is native to North America, but considered an invasive species in Europe, Australia and China. In Europe, the four main centres are: The Pannonian Plain, Ukraine, The Po Valley (Italy) and the Rhone Valley (France). Trends & Phenology: Birch pollen seasons have started earlier during the last decades. This trend appears have decreased during recent years despite increasing spring temperatures. Ragweed tends to experience less change in flowering date as ragweed flowering depends on photoperiod. Ragweed is increasing its distribution in Europe, but airborne concentrations of ragweed pollen are not universally increasing, e.g. due to control measures or pest attacks. Dispersion & transformation: The beginning of the birch pollen season is often heralded by episodes of Long Distance Transport (LDT) from the south. Similar LDT episodes are intermittently seen for ragweed, which can reach as far north as Scandinavia. Humidity and air pollution can modify pollen grains during atmospheric transport. This can cause a change in allergenic potential of the pollen grain and is a direction for future research including the effect of co-exposure of air pollution and the transformation of aeroallergens.
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Tese de mestrado em Biologia da Conservação, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2016
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In democratic polities, constitutional equilibria or balances of power between the executive and the legislature shift over time. Normative and empirical political theorists have long recognised that war, civil unrest, economic and political crises, terrorist attacks, and other events strengthen the power of the executive, disrupt and threaten constitutional politics, and damage democratic institutions: crises require swift action and executives are thought to be more capable than parliaments and legislatures of taking such actions. The terrorist attacks on New York and Washington on 11 September 2001 and the ensuing so-called 'war on terror' declared by President Bush clearly constituted a crisis, not only in the United States but also in other political systems, in part because of the US's hegemonic position in defining and shaping many other states' foreign and domestic policies. Dicey, Schmitt, and Rossiter suggest that critical events and political crises inevitably trigger the concentration of (emergency) powers in the hands of the executive. Aristotle and Machiavelli questioned the inevitability of this process. This article and the articles that follow in this Special Issue utilise empirical evidence, through the use of case studies of the United States, the United Kingdom, Russia, Australia, Israel, Italy and Indonesia, to address this debate. Specifically, the issue explores to what extent the external shock or crisis of 9/11 (and other terrorist attacks) and the ensuing 'war on terror' significantly changed the balance of executive-legislative relations from t (before the crisis) to t+1 (after the crisis) in these political systems, all of which were the targets of actual or foiled terrorist attacks. The most significant findings are that the shock of 9/11 and the 'war on terror' elicited varied responses by national executives and legislatures/parliaments and thus the balance of executive-legislative relations in different political systems; that, therefore, executive-legislative relations are positive rather than zero-sum; and that domestic political contexts conditioned these institutional responses.
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Congressional dominance theory holds that not only can the US Congress control the executive, it does. The terrorist attacks on New York and Washington on 11 September 2001 and the Bush administration's ensuing global 'war on terror' suggest a different result. Bush's response to 9/11 signalled not only new directions in US foreign and domestic policy but a new stage in the aggrandisement of presidential power in the United States and a further step in the marginalisation of the Congress. Informed by a constitutional doctrine unknown to the framers of the US Constitution, the Bush administration pursued a presidentialist or 'ultra-separationist' governing strategy that was disrespectful to the legislature's intended role in the separated system. Using its unilateral powers, in public and in secret, claiming 'inherent' authority from the Constitution, and exploiting the public's fear of a further terrorist attack and of endangering the lives of US troops abroad, the administration skilfully drove its legislation through the Congress. Occasionally, the Congress was able to extract concessions - notably in the immediate aftermath of 9/11, when partisan control of the government was split - but more typically, for most of the period, the Congress acquiesced to administration demands, albeit with the consolation of minor concessions. The administration not only dominated the lawmaking process, it also cowed legislators into legitimating often highly controversial (and sometimes illegal) administration-determined definitions of counter-terrorism and national security policy. Certainly, the Congress undertook a considerable amount of oversight during the period of the 'war on terror'; lawmakers also complained. But the effects on policy were marginal. This finding held true for periods of Democratic as well as Republican majorities.
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The infrastructure cloud (IaaS) service model offers improved resource flexibility and availability, where tenants - insulated from the minutiae of hardware maintenance - rent computing resources to deploy and operate complex systems. Large-scale services running on IaaS platforms demonstrate the viability of this model; nevertheless, many organizations operating on sensitive data avoid migrating operations to IaaS platforms due to security concerns. In this paper, we describe a framework for data and operation security in IaaS, consisting of protocols for a trusted launch of virtual machines and domain-based storage protection. We continue with an extensive theoretical analysis with proofs about protocol resistance against attacks in the defined threat model. The protocols allow trust to be established by remotely attesting host platform configuration prior to launching guest virtual machines and ensure confidentiality of data in remote storage, with encryption keys maintained outside of the IaaS domain. Presented experimental results demonstrate the validity and efficiency of the proposed protocols. The framework prototype was implemented on a test bed operating a public electronic health record system, showing that the proposed protocols can be integrated into existing cloud environments.
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Urban Computing (UrC) provides users with the situation-proper information by considering context of users, devices, and social and physical environment in urban life. With social network services, UrC makes it possible for people with common interests to organize a virtual-society through exchange of context information among them. In these cases, people and personal devices are vulnerable to fake and misleading context information which is transferred from unauthorized and unauthenticated servers by attackers. So called smart devices which run automatically on some context events are more vulnerable if they are not prepared for attacks. In this paper, we illustrate some UrC service scenarios, and show important context information, possible threats, protection method, and secure context management for people.
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Catastrophic events, such as wars and terrorist attacks, tornadoes and hurricanes, earthquakes, tsunamis, floods and landslides, are always accompanied by a large number of casualties. The size distribution of these casualties has separately been shown to follow approximate power law (PL) distributions. In this paper, we analyze the statistical distributions of the number of victims of catastrophic phenomena, in particular, terrorism, and find double PL behavior. This means that the data sets are better approximated by two PLs instead of a single one. We plot the PL parameters, corresponding to several events, and observe an interesting pattern in the charts, where the lines that connect each pair of points defining the double PLs are almost parallel to each other. A complementary data analysis is performed by means of the computation of the entropy. The results reveal relationships hidden in the data that may trigger a future comprehensive explanation of this type of phenomena.
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A crescente preocupação que envolve as questões ambientais a nível mundial, cada vez mais agravadas pelo comportamento irresponsável do Homem, conduziu à criação de métodos de avaliação dos impactes ambientais provocados por produtos e sistemas. Sendo o sector da construção responsável por grande parte desses impactes, é evidente a necessidade de aplicação de medidas que visem mitigar ou, no mínimo, reduzir até valores aceitáveis, essas agressões ao meio ambiente. Nesse âmbito, é natural que tenha surgido a ideia de aplicar uma metodologia tão precisa e rigorosa como a LCA ao sector da construção. No entanto, nos dias de hoje, as preocupações alargaram-se às vertentes social e económica que, juntamente com a vertente ambiental, formam o triângulo de equilíbrio do desenvolvimento sustentável. É precisamente essa avaliação tripartida que esta Dissertação pretende abordar, tentando aprofundar conhecimentos e fornecer alternativas, através da análise crítica, que possam contribuir para a melhoria contínua desta metodologia.
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Dissertação de Mestrado apresentada ao Instituto de Contabilidade e Administração do Porto para a obtenção de grau de Mestre em Auditoria, sob a orientação de Luís Silva Rodrigues
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Power laws, also known as Pareto-like laws or Zipf-like laws, are commonly used to explain a variety of real world distinct phenomena, often described merely by the produced signals. In this paper, we study twelve cases, namely worldwide technological accidents, the annual revenue of America׳s largest private companies, the number of inhabitants in America׳s largest cities, the magnitude of earthquakes with minimum moment magnitude equal to 4, the total burned area in forest fires occurred in Portugal, the net worth of the richer people in America, the frequency of occurrence of words in the novel Ulysses, by James Joyce, the total number of deaths in worldwide terrorist attacks, the number of linking root domains of the top internet domains, the number of linking root domains of the top internet pages, the total number of human victims of tornadoes occurred in the U.S., and the number of inhabitants in the 60 most populated countries. The results demonstrate the emergence of statistical characteristics, very close to a power law behavior. Furthermore, the parametric characterization reveals complex relationships present at higher level of description.
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Catastrophic events, such as wars and terrorist attacks, big tornadoes and hurricanes, huge earthquakes, tsunamis, floods, and landslides, are always accompanied by a large number of casualties. The size distribution of these casualties have separately been shown to follow approximate power law (PL) distributions. In this paper, we analyze the number of victims of catastrophic phenomena, in particular, terrorism, and find double PL behavior. This means that the data set is better approximated by two PLs instead of one. We have plotted the two PL parameters corresponding to all terrorist events occurred in every year, from 1980 to 2010. We observe an interesting pattern in the chart, where the lines, that connect each pair of points defining the double PLs, are roughly aligned to each other.
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Muitas instalações municipais são alvo de manutenção permanente, devido ao uso de produtos químicos que provocam a corrosão e degradação dos mais diversos materiais. Esta degradação acarreta custos elevados para os municípios e privação de uso de algumas instalações devido a manutenção curativa ou preventiva. Um estudo adequado do efeito dos produtos utilizados, poderia conduzir à utilização de materiais mais nobres, que aumentasse significativamente o tempo de vida dos produtos mais atacados pela degradação por corrosão, através de estudos que permitissem avaliar a relação custo-benefício e, caso esta fosse favorável, proceder à substituição de determinados componentes em materiais relativamente fracos, por outros com uma maior capacidade para resistir aos ataques produzidos pelo meio em que estão inseridos. Este estudo foi efectuado com vista a estudar a degradação de determinados materiais expostos essencialmente à acção do Cloro em instalações municipais, permitindo assim seleccionar novos materiais que permitissem uma vida útil dos componentes mais alargada, estudando convenientemente a relação custo-benefício. Foi possível observar que a introdução de alguns materiais mais nobres, poderá reduzir drasticamente as operações de manutenção, diminuindo os custos e reduzindo também o tempo de indisponibilidade dos equipamentos municipais.
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O fim da Guerra Fria é um caso inédito de mudança pacífica da estrutura internacional, em que os Estados Unidos e a União Soviética transcendem a divisão bipolar para decidir os termos da paz no quadro das instituições que definem o modelo de ordenamento multilateral, consolidando a sua legitimidade. Nesse contexto, ao contrário dos casos precedentes de reconstrução internacional no fim de uma guerra hegemónica, o novo sistema do post-Guerra Fria, caracterizado pela unipolaridade, pela regionalização e pela homogeneização, forma-se num quadro de continuidade institucional. A ordem política do post-Guerra Fria é um sistema misto em que as tensões entre a hierarquia unipolar e a anarquia multipolar, a integração global e a fragmentação regional e a homogeneidade e a heterogeneidade política, ideológica e cultural condicionam as estratégias das potências. As crises internacionais vão pôr à prova a estabilidade da nova ordem e a sua capacidade para garantir mudanças pacíficas. A primeira década do post-Guerra Fria mostra a preponderância dos Estados Unidos e a sua confiança crescente, patente nas Guerras do Golfo Pérsico e dos Balcãs, bem como na crise dos Estreitos da Formosa. A reacção aos atentados do "11 de Setembro" revela uma tentação imperial da potência unipolar, nomeadamente com a invasão do Iraque, que provoca uma crise profunda da comunidade de segurança ocidental. A vulnerabilidade do centro da ordem internacional é confirmada pela crise constitucional europeia e pela crise financeira global. Essas crises não alteram a estrutura de poder mas aceleram a erosão da ordem multilateral e criam um novo quadro de possibilidades para a evolução internacional, que inclui uma escalada dos conflitos num quadro de multipolaridade regional, uma nova polarização entre as potências democráticas conservadoras e uma coligação revisionista autoritária, bem como a restauração de um concerto entre as principais potências internacionais.
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Abnormalities in the topology of brain networks may be an important feature and etiological factor for psychogenic non-epileptic seizures (PNES). To explore this possibility, we applied a graph theoretical approach to functional networks based on resting state EEGs from 13 PNES patients and 13 age- and gender-matched controls. The networks were extracted from Laplacian-transformed time-series by a cross-correlation method. PNES patients showed close to normal local and global connectivity and small-world structure, estimated with clustering coefficient, modularity, global efficiency, and small-worldness (SW) metrics, respectively. Yet the number of PNES attacks per month correlated with a weakness of local connectedness and a skewed balance between local and global connectedness quantified with SW, all in EEG alpha band. In beta band, patients demonstrated above-normal resiliency, measured with assortativity coefficient, which also correlated with the frequency of PNES attacks. This interictal EEG phenotype may help improve differentiation between PNES and epilepsy. The results also suggest that local connectivity could be a target for therapeutic interventions in PNES. Selective modulation (strengthening) of local connectivity might improve the skewed balance between local and global connectivity and so prevent PNES events.