Over the past few decades, the growth of the urban population has been remarkable. Nowadays, 50% of the population lives in urban areas, and forecasts point that by 2050 this number will reach 70%. Today, 64% of all travel made is within urban environments and the total amount of urban kilometers traveled is expected to triple by 2050. Thus, seeking novel solutions for urban mobility becomes paramount for 21st century society. In this work, we discuss the performance of vehicular networks. We consider the metric Delta Network. The Delta Network characterizes the connectivity of the vehicular network through the percentage of travel time in which vehicles are connected to roadside units. This article reviews the concept of the Delta Network and extends its study through the presentation of a general heuristic based on the definition of scores to identify the areas of the road network that should receive coverage. After defining the general heuristic, we show how small changes in the score computation can generate very distinct (and interesting) patterns of coverage, each one suited to a given scenario. In order to exemplify such behavior, we propose three deployment strategies based on simply changing the computation of scores. We compare the proposed strategies to the intuitive strategy of allocating communication units at the most popular zones of the road network. Experiments show that the strategies derived from the general heuristic provide higher coverage than the intuitive strategy when using the same number of communication devices. Moreover, the resulting pattern of coverage is very interesting, with roadside units deployed a circle pattern around the traffic epicenter.

Intelligent Transport Systems can rely on communications networks specifically designed for vehicles, which can subsidize new forms of traffic management, such as the implementation of traffic lights, roads and intelligent signs. From this perspective, this work presents the Omega Deployment, a strategy that allows to define the places of vehicle communication infrastructure deployment aiming to ensure that a given share of the fleet is always within the reach of antennas, guaranteeing a minimum level of connectivity for the network, even when facing changes in the flow of vehicles. This work discusses the Omega Deployment and proposes two strategies for its solution through the greedy paradigm and the GRASP meta-heuristic. As a baseline, the work considers the intuitive strategy to cover the most popular areas. The results demonstrate that the intuitive strategy may require up to 25% more coverage of the entire road network and that the GRASP-based strategy achieves a saving of 0.38% compared to the greedy strategy, keeping the same coverage.

Static filling pressures correlate poorly with fluid responsiveness, prompting widespread adoption of dynamic hemodynamic indicators such as stroke volume variation (SVV), pulse pressure variation (PPV), and the plethysmographic variability index (PVI) to guide perioperative fluid administration. This review synthesizes the physiological basis of these indices, their diagnostic accuracy across surgical settings including cardiac, thoracic, laparoscopic, and orthopedic procedures, and the outcome evidence from goal-directed fluid protocols built around them. Diagnostic accuracy for SVV and PPV is strong under controlled ventilation with adequate tidal volume and sinus rhythm, but degrades meaningfully with low tidal volume protective ventilation, one-lung ventilation, arrhythmia, and pneumoperitoneum, while PVI offers a noninvasive alternative that is itself confounded by low peripheral perfusion states. Outcome trials, particularly within enhanced recovery colorectal surgery programs, show that dynamic-index-guided therapy reliably outperforms liberal or unstructured fluid administration but shows less consistent benefit when compared against a well-designed restrictive fluid protocol. We conclude that dynamic indicators are best applied within their validated physiological preconditions and as an adjunct to, rather than a replacement for, a restrictive-leaning baseline fluid strategy and integrated clinical judgment.