1,721,327 research outputs found
Levosimendan in Sepsis.
Full text linkCommentum to "Levosimendan for the Prevention of Acute Organ Dysfunction in Sepsis
Ulvan as a new type of biomaterial from renewable resources: Functionalization and hydrogel preparation
No full textUlvan, a sulfated cell-wall polysaccharide extracted from green seaweeds, is functionalized by grafting methacryloyl moieties as a radical polymerizable group and photopolymerized under UV irradiation in order to attain biodegradable hydrogels. The functionalization reaction is carried out by using methacrylic anhydride or glycidyl methacrylate according to two basic procedures applied to polysaccharides. The functionalization of Ulvan is determined by FT-IR and (1)H NMR spectroscopy and confirmed by DSC analysis. Hydrogels were characterized by FT-IR and by (1)H NMR spectroscopies and their swelling behaviour assessed in terms of degree of swelling using PBS 1 x pH 7.4 as a medium in order to check their stability under physiological conditions
Effects of levosimendan on systemic and regional hemodynamics in septic myocardial depression [6]
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"Terlipressin in the treatment of septic shock: the earlier the better"?
No full textTerlipressin, a long-acting vasopressinergic V1 agonist, is increasingly used to increase mean arterial blood pressure in the common setting of catecholamine-refractory septic shock. Traditionally, terlipressin has been used as drug of last resort and administered as intermittent high-dose bolus infusion (1-2 mg every 4 to 6 hours). Recent experimental and clinical evidence, however, suggests that terlipressin may also be used as a low-dose continuous infusion (1-2 microg kg(-1) h(-1)) in the early course of the disease. This approach may sufficiently increase systemic blood pressure and thereby prevent unwanted side effects, such as exaggerating increases in peripheral resistance or rebound hypotension. Small-scale clinical studies suggest that low-dose terlipressin, when given as a first-line vasopressor agent, is safe. Randomised, clinical multicenter trials are now needed to investigate whether or not early institution of low-dose continuous terlipressin infusion improves overall outcome of patients suffering from vasodilatory shock states
Robust Low-Thrust Trajectory Optimization Using Convex Programming and a Homotopic Approach
Full text linkA robust algorithm to solve the low-thrust fuel-optimal trajectory optimization problem for interplanetary spacecraft is developed in this article. The original nonlinear optimal control problem is convexified and transformed into a parameter optimization problem using an arbitrary-order Gauss-Lobatto discretization scheme with nonlinear control interpolation. A homotopic approach that considers the energy-to-fuel smoothing path is combined with an adaptive second-order trust-region mechanism to increase performance. The overall robustness is assessed in several fuel-optimal transfers with poor initial guesses. The results show a superior performance in terms of convergence and computational time compared to standard convex programming approaches in the literature
Warm-Start of Interior-Point Methods Applied to Sequential Convex Programming
Full text linkSequential convex programming (SCP) is an iterative technique that solves nonconvex optimization problems by considering a sequence of convex subproblems whose solutions eventually converge, under certain conditions, to the solution of the original problem. The most common convex solvers divide in interior-point, first-order, and active-set methods. In particular, the former have shown good performance. Even though SCP is quite efficient in terms of required computational time with respect to standard nonlinear optimization solvers, its potential is still not completely exploited when interior-point convex solvers are used as no information on the solution of a previous convex subproblem is used to construct the initial guess for the strictly-related following one. This is because interior-point methods are notoriously difficult to warm-start. In this paper, a technique to warm-start interior-point methods that solve secondorder cone programs (SOCP) is developed and integrated within the sequential convex programming. The strategy can be used independently of the specific problem as long as it is expressed as a standard SOCP. The low-thrust space trajectory optimization problem is considered to assess the efficacy of the proposed strategy through extensive numerical simulations. It is shown that the warm-start algorithm outperforms the standard algorithm in terms of computational time and overall convergence when the widely-used solver ECOS is used
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