Intracranial aneurysms and subarachnoid hemorrhage: Clinical studies on diagnosis and treatment

Computerized tomography angiography (CTA) can be performed quicker, safer and cheaper than digital subtraction angiography (DSA) in patients after aneurysmal subarachnoid hemorrhage (SAH). However, DSA is still regarded as the gold standard in the diagnosis of intracranial ruptured aneurysms. No studies have specifically addressed the value of CTA in planning of endovascular treatment of ruptured aneurysms. Mathieu van der Jagt investigates the diagnostic value of CTA for endovascular treatment compared with DSA, in cooperation with Radiology. He hypothesizes is that, at least in a subset of patients, CTA suffices and DSA can be omitted in the planning of endovascular treatment. Another project concerns a systematic review on rupture rate of unruptured intracranial aneurysms (UIAs), estimating the rupture rate of UIAs based on the available observational studies. The statistical method used will allow for correction for methodological quality per study, lea! ding to an estimate of rupture rate that is based on less biased data. The PhD project also evaluates the localizing value of blood distribution on CTA for the location of ruptured intracranial aneurysm; it includes a cohort study on the impact of early surgery on overall outcome after aneurysmal SAH

Fluid management of the neurological patient: A concise review

Maintenance fluids in critically ill brain-injured patients are part of routine critical care. Both the amounts of fluid volumes infused and the type and tonicity of maintenance fluids are relevant in understanding the impact of fluids on the pathophysiology of secondary brain injuries in these patients. In this narrative review, current evidence on routine fluid management of critically ill brain-injured patients and use of haemodynamic monitoring is summarized. Pertinent guidelines and consensus statements on fluid management for brain-injured patients are highlighted. In general, existing guidelines indicate that fluid management in these neurocritical care patients should be targeted at euvolemia using isotonic fluids. A critical appraisal is made of the available literature regarding the appropriate amount of fluids, haemodynamic monitoring and which types of fluids should be administered or avoided and a practical approach to fluid management is elaborated. Although hypovolemia is bound to contribute to secondary brain injury, some more recent data have emerged indicating the potential risks of fluid overload. However, it is acknowledged that many factors govern the relationship between fluid management and cerebral blood flow and oxygenation and more research seems warranted to optimise fluid management and improve outcomes

Airfoil optimization by using the Manifold Mapping method

In this report it is investigated if the Manifold Mapping method can be used in airfoil optimization. Before the method can be implemented, a suitable airfoil parametrization must be chosen. Furthermore a coarse and fine model must be assigned. These models are the key to success for the Manifold Mapping method. If two models are chosen that are completely different from each other, the Manifold Mapping will not work properly. Furthermore, if two models are chosen that are very similar to each other, the benefit in reducing computational cost will be only marginal. In this report the Manifold Mapping method will be explained in detail and applied to airfoil design. The approach is validated by using a test case, which will also be explained in detail. Furthermore recommendations and extensions will be given in the last chapter

Inhibition of pancreatic cholesterol esterase reduces cholesterol absorption in the hamster

BACKGROUND: Pancreatic cholesterol esterase has three proposed functions in the intestine: 1) to control the bioavailability of cholesterol from dietary cholesterol esters; 2) to contribute to incorporation of cholesterol into mixed micelles; and 3) to aid in transport of free cholesterol to the enterocyte. Inhibitors of cholesterol esterase are anticipated to limit the absorption of dietary cholesterol. RESULTS: The selective and potent cholesterol esterase inhibitor 6-chloro-3-(1-ethyl-2-cyclohexyl)-2-pyrone (figure 1, structure 1) was administered to hamsters fed a high cholesterol diet supplemented with radiolabeled cholesterol ester. Hamsters were gavage fed (3)H-labeled cholesteryl oleate along with inhibitor 1, 0–200 micromoles. Twenty-four hours later, hepatic and serum radioactive cholesterol levels were determined. The ED(50 )of inhibitor 1 for prevention of the uptake of labeled cholesterol derived from hydrolysis of labeled cholesteryl oleate was 100 micromoles. The toxicity of inhibitor 1 was investigated in a 30 day feeding trial. Inhibitor 1, 100 micromoles or 200 micromoles per day, was added to chow supplemented with 1% cholesterol and 0.5% cholic acid. Clinical chemistry urinalysis and tissue histopathology were obtained. No toxicity differences were noted between control and inhibitor supplemented groups. CONCLUSIONS: Inhibitors of cholesterol esterase may be useful therapeutics for limiting cholesterol absorption

Giant scaphitid ammonites from the Maastrichtian of Europe

Giant scaphitid ammonites from the Maastrichtian of Europe have generally been assigned to Acanthoscaphites NOWAK, 1911. Prior to the present study, this genus comprised five species: A. tridens (KNER, 1848), A. varians (LOPUSKI, 1911), A. verneuilianus (D'ORBIGNY, 1841), A. sp. of KENNEDY (1987) and A. sp. of KENNEDY & CHRISTENSEN (1997). Of the first-named taxon, material from Aachen-Schneeberg of Early Maastrichtian age, including the specimen illustrated by HOLZAPFEL (1887-89) long thought to have been lost, is described. Recently collected topotype material from Kazimierz Dolny, and from Rejowiec (Poland), of latest Maastrichtian age (Belemnella kazimiroviensis Zone), allows A. varians to be revised. Specimens from the late Early and early Late Maastrichtian of NW Europe, assigned to A. varians, differ consistently in details of ornament, and are assigned to a new subspecies, A. v. blaszkiewiczi n. subsp. Style of ribbing and tuberculation of the varians stock differs from that of A. tridens to such an extent that a new subgenus, Euroscaphites n. subgen., is erected, with varians as type species. The Late Maastrichtian "Acanthoscaphites" verneuilianus, only known from phragmocones, is provisionally assigned to the new subgenus. The other two species previously referred to Acanthoscaphiles, viz. A. sp. of KENNEDY (1987) and A. sp. of KENNEDY & CHRISTENSEN (1997), both of Late Maastrichtian age, cannot be assigned confidently to either subgenus

Additional records of scaphitid ammonites from the basal upper Maastrichtian (Upper Cretaceous) of eastern Poland

New records of rare and/or poorly known scaphitid ammonites are presented from the basal upper Maastrichtian (Upper Cretaceous) white chalk exposed at Chelm quarry, Lublin Upland (eastern Poland). The described and illustrated material comprises four specimens, all preserved as composite moulds, and includes a well-preserved microconch of Hoploscaphites schmidi (BIRKELUND, 1982), fragmentary specimens of H. felderi KENNEDY, 1987 and Acanthoscaphites (Euroscaphites) varians blaszkiewiczi JAGT, KENNEDY & MACHALSKI, 1999, as well as a pathological macroconch of Hoploscaphites constrictus lvivensis MACHALSKI, 2005b

A Parameterization of Polynomials on Distributed States and a PIE Representation of Nonlinear PDEs

Partial Integral Equations (PIEs) have previously been used to represent systems of linear (1D) Partial Differential Equations (PDEs) with homogeneous Boundary Conditions (BCs), facilitating analysis and simulation of such distributed-state systems. In this paper, we extend these result to derive an equivalent PIE representation of scalar-valued, 1D, polynomial PDEs, with linear, homogoneous BCs. To derive this PIE representation of polynomial PDEs, we first propose a new definition of polynomials on distributed states $\mathbf{u}\in L_2[a,b]$, that naturally generalizes the concept of polynomials on finite-dimensional states to infinite dimensions. We then define a subclass of distributed polynomials that is parameterized by Partial Integral (PI) operators. We prove that this subclass of polynomials is closed under addition and multiplication, providing formulae for computing the sums and products of such polynomials. Applying these results, we then show how a large class of polynomial PDEs can be represented in terms of distributed PI polynomials, proving equivalence of solutions of the resulting PIE representation to those of the original PDE. Finally, parameterizing quadratic Lyapunov functions by PI operators as well, we formulate a stability test for quadratic PDEs as a linear operator inequality optimization problem, which can be solved using the PIETOOLS software suite. We illustrate how this framework can be used to test stability of several common nonlinear PDEs

A PIE Representation of Coupled Linear 2D PDEs and Stability Analysis using LPIs

We introduce a Partial Integral Equation (PIE) representation of Partial Differential Equations (PDEs) in two spatial variables. PIEs are an algebraic state-space representation of infinite-dimensional systems and have been used to model 1D PDEs and time-delay systems without continuity constraints or boundary conditions -- making these PIE representations amenable to stability analysis using convex optimization. To extend the PIE framework to 2D PDEs, we first construct an algebra of Partial Integral (PI) operators on the function space L_2[x,y], providing formulae for composition, adjoint, and inversion. We then extend this algebra to R^n x L_2[x] x L_2[y] x L_2[x,y] and demonstrate that, for any suitable coupled, linear PDE in 2 spatial variables, there exists an associated PIE whose solutions bijectively map to solutions of the original PDE -- providing conversion formulae between these representations. Next, we use positive matrices to parameterize the convex cone of 2D PI operators -- allowing us to optimize PI operators and solve Linear PI Inequality (LPI) feasibility problems. Finally, we use the 2D LPI framework to provide conditions for stability of 2D linear PDEs. We test these conditions on 2D heat and wave equations and demonstrate that the stability condition has little to no conservatism

A PIE Representation of Delayed Coupled Linear ODE-PDE Systems and Stability Analysis using Convex Optimization

Partial Integral Equations (PIEs) have been used to represent both systems with delay and systems of Partial Differential Equations (PDEs) in one or two spatial dimensions. In this paper, we show that these results can be combined to obtain a PIE representation of any suitably well-posed 1D PDE model with constant delay. In particular, we represent these delayed PDE systems as coupled systems of 1D and 2D PDEs, proving that a PIE representation of both the 1D and 2D subsystems can be derived. Taking the feedback interconnection of these PIE representations, we then obtain a 2D PIE representation of the 1D PDE with delay. We show that this PIE representation can be coupled to that of an Ordinary Differential Equation (ODE) with delay, to obtain a PIE representation of delayed linear ODE-PDE systems. Next, based on the PIE representation, we formulate the problem of stability analysis as a Linear Operator Inequality (LPI) optimization problem which can be solved using the PIETOOLS software suite. We apply the result to several examples from the existing literature involving delay in the dynamics as well as the boundary conditions of the PDE

The fossil record of the family Benthopectinidae (Echinodermata, Asteroidea), a reappraisal

Fossils assigned to the predominantly deep-sea asteroid family Benthopectinidae Verrill, 1894 are described and their affinities reappraised. Detailed comparative morphology of ambulacrals, adambulacrals and marginal ossicles has revealed that only some extinct taxa fall within the morphological range of the modern representatives of the family. These include Jurapecten hessi Gale, 2011, J. infrajurensis sp. nov. (both Jurassic), J. dhondtae sp. nov. (Upper Cretaceous) and Nearchaster spinosus (Blake, 1973) comb. nov. (Lower Oligocene). A new Late Cretaceous genus, Punkaster gen. nov. (P. spinifera gen. et sp. nov. and P. ruegenensis gen. et sp. nov.), appears to be a highly derived benthopectinid. A possible benthopectinid is described from the Upper Triassic (Carnian) of China. Other described records are distantly related to, but convergent in gross morphology with, benthopectinids. Thus, Plesiastropecten hallovensis Peyer, 1944 is here referred to the Jurassic spinulosidan family Plumasteridae Gale, 2011 and Xandarosaster hessi Blake, 1984 is interpreted as Spinulosida Perrier, 1884 incertae sedis. The mid-Cretaceous Alkaidia sumralli Blake & Reid, 1998 is reassigned to the Forcipulatida (Zorocallina). The “fossil benthopectinid” of Spencer & Wright in Moore (1966) is shown to belong to the goniopectinid genus Chrispaulia Gale, 2005, of which two new Cretaceous species are described, C. wrightorum sp. nov. and C. spinosa sp. nov. Finally, we consider Henricia? venturana Durham & Roberts, 1948 to be an indeterminate asteroid