1,721,610 research outputs found
An Operative Framework for the Optimal Selection of Centrifugal Pumps As Turbines (PATs) in Water Distribution Networks (WDNs)
Full text linkThe current significant increase in energy consumption has resulted in the need to develop and implement effective approaches for defining alternative and sustainable solutions to couple primary resources with supporting methods of energy generation. In the field of effective water distribution network (WDN) management, the suitability of combining pressure regulation with small-scale hydropower generation is attracting even more interest, given that it can possibly reduce water leakages, as well as produce attractive rates of renewable energy. Specifically, pumps as turbines (PATs) are widely considered a viable solution because they combine hydraulic benefits with affordable investment and management costs. Nevertheless, despite several approaches available in the literature for the optimal selection and management of PATs, choosing the most suitable device to be installed in the network is still a challenge, especially when electrical regulation is arranged to modulate the PAT rotational speed and optimize the produced energy. Several approaches in the literature provide interesting solutions for assessing the effectiveness of electrical regulation when a PAT is installed within a water network. However, most of them require specific knowledge of the PAT mechanical features or huge computational efforts and do not support swift PAT selection. To overcome this lack of tools, in this work, an operative framework for the preliminary assessment of the main features (the head drop and the produced power at the best efficiency point (BEP), the impeller diameter and the rotational speed) of a PAT is proposed, aimed at both maximizing the daily produced energy and performing challenging economic selection. Then, it is assessed by estimations of the corresponding payback period (PP) and the net present value (NPV
Aspetti psicologici dell’infertilità maschile: la relazione tra alessitimia e parametri seminali e ormonali.
No full textThe Role of rescue therapies in the treatment of severe ARDS
Full text linkARDS is characterized by a non-cardiogenic pulmonary edema with bilateral chest radiograph opacities and hypoxemia refractory to oxygen therapy. It is a common cause of admission to the ICU due to hypoxemic respiratory failure requiring mechanical ventilation. Corticosteroids are not recommended in ARDS patients. Rescue therapies alleviate hypoxemia in patients unable to maintain reasonable oxygenation: recruitment maneuvers, prone positioning, inhaled nitric oxide, high-frequency oscillatory ventilation, and extracorporeal membrane oxygenation improve oxygenation, but their impact on mortality remains unproven. Restrictive fluid management seems to be a favorable strategy with no significant reduction in 60-d mortality. Future studies are needed to clarify the efficacy of these therapies on outcomes in patients with severe ARDS, and institution of these therapies may be considered on a case-by-case basis
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Hydroxyethyl starch on kidney and haemostatic function in cardiac surgical patients: is a non-inferiority study design appropriate for this setting?
No full textWe read with great interest the paper by Duncan et al. on the effect of hydroxyethyl starch (HES) on kidney and haemostatic function in cardiac surgical patients [1]. In their single‐centre, triple‐blind, parallel group, randomised ‘non inferiority’ trial, the authors tested the primary hypothesis that kidney function was not worse in cardiac surgery patients who received HES compared with patients assigned to receive albumin. The authors concluded that reported evidence proves “lack of harm” due to similar results between the groups.
The authors report in their introduction that “according to two studies with inconsistent results, HES appeared to increase mortality and kidney injury in critically ill, including septic patients, who received HES” was the background of their study. To present state‐of‐the‐art clinical evidence is especially relevant when patients are asked to provide informed consent and there is evidence of HES‐associated increased mortality proven by a large meta‐analysis [2, 3]. Controversies regarding peri‐operative use of HES have increasingly been reported to both the US Food and Drugs Administration and the European Medicines Agency [2, 3]. These include the exclusion of patients with pre‐operative impaired renal function that, as reported by the authors, were excluded from the present study. Given these premises it seems more appropriate to convey to readers and stakeholders (including patients and their relatives) a clearer conclusion: only in patients at low risk for postoperative renal damage is there evidence of additional harm when HES is used compared with albumin. Hence, as already underlined by Futier et al. “... these findings do not support the use of HES for volume replacement therapy in such patients” [4]. Furthermore, the present study does not address a more relevant question: what is the benefit? [5].
In light of the existing concerns on HES use, this study leaves several unanswered questions: how should patients be informed when they are asked to participate in a clinical trial that may randomise them to receive HES? How can a prestigious research group consider it appropriate to adopt a ’non‐inferiority’ study design to evaluate the safety profile of a controversial drug such as HES, when any proven beneficial effects (if there are any) remain unanswered
Hydroxyethyl starch and fluid resuscitation. Patient-oriented outcome is the “right way”
No full texthe intensive care unit (ICU) [1].
Fluid resuscitation is a relevant topic in critical care and the debate on optimal fluid management is evolving. Hydroxyethyl starch (HES)
is a colloid used for volume replacement therapy with a controversial history: recently HES-derived products' market authorizations have
been reevaluated and more restrictive rules have been released [2-5].
In the United States, the Food and Drug Administration has been requested to withdraw HES-based products by Public Citizen, a nonprofit
consumer advocacy organization [2,3].
Mechanical ventilation and neurocritical patients. Is there a role for anti-neuroinflammatory therapies?
Full text linkWe read with great attention and interest the review
by Robba and colleagues on mechanical ventilation
(MV) in patients with acute ischemic stroke [1].
The authors examined the pathophysiology of stroke
and the risk for pulmonary complications (brain-lung
“dangerous” crosstalk, immunological response after
stroke, stroke-associated pneumonia, and dysphagia)
then concluding with useful recommendations on
optimal ventilator settings and therapeutic strategies
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