RESUMO
In this paper, we aim to open up new perspectives in the field of autonomous aerial surveillance and target tracking systems, by exploring an alternative that, surprisingly, and to the best of the authors' knowledge, has not been addressed in that context by the research community thus far. It can be summarized by the following two questions. Under the scope of such applications, what are the implications and possibilities offered by mounting several steerable cameras onboard of each aerial agent? Second, how can optimization algorithms benefit from this new framework, in their attempt to provide more efficient and cost-effective solutions on these areas? The paper presents the idea as an additional degree of freedom to be exploited, which can enable more efficient alternatives in the deployment of such applications. As an initial approach, the problem of the optimal positioning with respect to a set of targets of one single agent, equipped with several onboard tracking cameras with different or variable focal lengths, is addressed. As a consequence of this allowed heterogeneity in focal lengths, the notion of distance needs to be adapted into a notion of optical range, as the agent can trade longer Euclidean distances for correspondingly longer focal lengths. Moreover, the proposed optimization indices try to balance, in an optimal way, the verticality of the viewpoints along with the optical range to the targets. Under these premises, several positioning strategies are proposed and comparatively evaluated.
Assuntos
Esportes , Dispositivos Aéreos não Tripulados , AlgoritmosRESUMO
BACKGROUND AND PURPOSE: The STARS trial (Stroke Treatment With Acute Reperfusion and Simvastatin) was conducted to demonstrate the efficacy and safety of simvastatin treatment in acute stroke. METHODS: STARS07 was a multicentre, phase IV, prospective, randomized, double-blind, placebo-controlled trial. Patients with Acute ischemic stroke recruited within 12 hours from symptom onset were randomized to oral simvastatin 40 mg or placebo, once daily for 90 days. Primary outcome was proportion of independent patients (modified Rankin Scale score of ≤2) at 90 days. Safety end points were hemorrhagic transformation, hemorrhagic events, death, infections, and serious adverse events. RESULTS: From April 2009 to March 2014, 104 patients were included. Fifty-five patients received intravenous tissue-type plasminogen activator. No differences were found between treatment arms regarding the primary outcome (adjusted odds ratio, 0.99 [0.35-2.78]; P=0.98). Concerning safety, no significant differences were found in the rate of hemorrhagic transformation of any type, nor symptomatic hemorrhagic transformation. There were no differences in other predefined safety outcomes. In post hoc analyses, for patients receiving tissue-type plasminogen activator, a favorable effect for simvastatin treatment was noted with higher proportion of patients experiencing major neurological recovery (adjusted odds ratio, 4.14 [1.18-14.4]; P=0.02). CONCLUSIONS: Simvastatin plus tissue-type plasminogen activator combination seems safe in acute stroke, with low rates of bleeding complications. Because of the low recruitment, the STARS trial was underpowered to detect differences in simvastatin efficacy. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01073007.