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The nonlinear rheology of three selected commercial low-density polyethylenes (LDPE) is measured in uniaxial extensional flow. The measurements are performed using three different devices including an extensional viscosity fixture (EVF), a homemade filament stretching rheometer (DTU-FSR) and a commercial filament stretching rheometer (VADER-1000). We show that the measurements from the EVF are limited by a maximum Hencky strain of 4, while the two filament stretching rheometers are able to probe the nonlinear behavior at larger Hencky strain values where the steady state is reached. With the capability of the filament stretching rheometers, we show that LDPEs with quite different linear viscoelastic properties can have very similar steady extensional viscosity. This points to the potential for independently controlling shear and extensional rheology in certain rate ranges.

The most important parameters influencing the pressure drop over a reacting catalyst bed are analyzed using a multiphase multicomponent flow model. The model, in which the gas and liquid phases are treated as separate fluids, simulates the flow of highly concentrated hydrogen peroxide from a tank, through the injector, into the catalyst bed to the nozzle. It contains submodels to describe the interphase mass, momentum, and energy transfer occurring in the catalyst bed, in which it is assumed there is a pellet-based catalyst structure. The main purpose is to investigate the influence of pellet shape and dimensions on the pressure drop over the bed and the required bed length. The model has been verified and validated against experimental data and shows improved predictions of the pressure drop compared with traditionally employed pressure drop models. It is shown that cylindrical pellets with a diameter to length ratio larger than two give a lower pressure drop for a given bed length than spherical pellets...

22 páginas, 18 figuras, 5 tablas, 17 esquemas.-- et al., As part of a continuing scientific challenge, a substantial effort during the past few decades has been devoted towards altering the selectivity of chemical transformations by arranging the potential reactants in a number of organized and confining media. Such systems, having features significantly different from those of isotropic solutions, include, for example, micelles, microemulsions, molecular aggregates, liquid crystals, and zeolites. Among these materials, stimuli-response gels constitute another important class of nanostructured and dynamic systems with high active surface areas and remarkable diffusion properties. Within this group, polymer gels have been traditionally used to obtain catalytic and reactive soft materials. Moreover, gels made of low-molecular-weight compounds represent a major novelty in this area as potential soft-vessels to carry out chemical reactions with control on product selectivity. In addition, the possibility of integrating switchable catalytic functions in both organo- and hydrogels shall accelerate the development of robust platforms for the ‘bottom–up’ tailor-fabrication of more sophisticated functional materials. The present critical review reports on the most important results published during the last decade regarding the use of ‘smart’ gels that has displayed promising properties as selective soft-nanoreactors and/or heterogeneous recyclable catalysts (152 references)., D.D.D. thanks Universität Regensburg and the Alexander von Humboldt Foundation for financial support.

Three high pressure ethylene vinylacetate (EVA) copolymers having a mol % VA between 0 and 20 are transformed into ethylene vinylalcohol vinylacetate (EVALVA) terpolymers by an homogeneous saponification method. The acetoxy-hydroxide conversion proved to be caused by two similtaneously occuring reactions, a saponification and a transesterification. The overall reaction, however, could be discribed by second order kinetics. The lower VA conversion rate of EVA types having 3.5 vs 12.0 and 18.8 mol % VA was explained a combined steric and neighbouring group effect. Finally a mechanism applicable to any EVA type copolymer was forwarded to comprehend the acetoxy-hydroxide conversion.

The influence of 4 reaction parameters on the homogeneous saponification method is examined. Firstly, the use of xylene, cyclohexane and tetrachloromethane instead of toluene indicates some experimental complications. It could however be concluded that a changing solubility parameter had a minor effect on the VA conversion rate. Secondly, reactions in an ethanol or a 2-propanol medium are faster than when a methanol medium is used. Thirdly, it is not possible to control the % wt conversion VA only by a suitable amount of potassiumhydroxide. A larger than expected % wt conversion VA is observed, due to a base catalyzed transesterification sidereaction. Fourthly, a methanol concentration change influences the contribution of the sidereaction. Furthermore, the methanol and potassiumhydroxide concentration influence, on the VA conversion rate is not independent of each other.

The clinical significance of infection in bone marrow failure has been demonstrated in the case histories of five patients with panmyelopathy. In these patients the development of infections was associated with a hematologic relapse. With successful treatment of infections a marked improvement of the hematologic status occurred, characterized by at least a decrease in transfusion requirement and sometimes an increase in leucocyte count and the number of platelets. In one case (no. 1) a complete remission occurred. Apparently infection may lead to acute bone marrow failure in patients with panmyelopathy, possibly by increasing the load on a damaged organ which is already working at the maximum of its limited capacity. Adequate treatment and prevention of infections is therefore of major importance for the hematologic status of those patients.

Extrudate swell is an important viscoelastic feature of polymer melt processing. Experimental work with linear polymers has identified extrudate swell to depend strongly on average molar mass and molar mass distribution. Unfortunately there was no method identified to distinguish the relative effects of average mass and polydispersity. This paper revisits previously published experimental data on high-density polyethylenes and proposes a model to understand the coupled effect of these two molecular variables. The model connects findings from double reptation models via the recoverable compliance to extrudate swell. The reported results provide support to the model and lead to a better understanding of the important role of high-mass fractions in polydisperse polymers.

The chemical industry is in the process of reinventing itself to ensure its sustainability. In a global economy, the challenges are huge for balancing environmental, economic and societal aspirations that either maintain or enhance the quality of life in an affordable manner. Although today no single path exists towards sustainable materials, there are a number of emerging technologies that have the potential to contribute to the drivers of twenty-first century society. Exploring the small world of atoms and molecules has provided nanotechnology and biotechnology. Nanobiotechnology has revealed a number of opportunities and insights with the potential of rejuvenating the chemical industry. It provides 'chemistry' with a 'new face' and purpose. The more effective use of biomass and the application of molecular self-organisation principles illustrate the new directions science and technology is moving into, and contributing to a sustainable society.

We consider viscoelastic flows over topography in the presence of inertia. Such flows are modelled by an integral-boundary-layer approximation of the equations of motion and wall/free-surface boundary conditions. Steady states for flows over a step-down in topography are characterized by a capillary ridge immediately before the entrance to the step. A similar capillary ridge has also been observed for non-inertial Newtonian flows over topography. The height of the ridge is found to be a monotonically decreasing function of the Deborah number. Further, we examine the interaction between capillary ridges and excited non-equilibrium inertia/viscoelasticity-driven solitary pulses. We demonstrate that ridges have a profound influence on the drainage dynamics of such pulses: they accelerate the drainage process so that once the pulses pass the topographical feature they become equilibrium ones and are no longer excited.

21st century industrial activities are faced with the challenge of sustainable development. The current state of affairs of the chemical industry as seen in its historical context offers a perspective for the future. The chemical industry developed in the 19th century from efforts to replace naturally occurring materials e.g. rubber and ivory. Revisiting nature for inspiration with today's far more advanced chemistry knowledge offers an abundance of opportunities for fundamental research as well as applied technology development with commercial perspectives. Beyond the covalent bond as practiced by synthetic petrochemistry for making a wealth of small-, oligo-, and macro-molecules there exists a vast area, barely explored, of bio-materials with seemingly endless structure-forming capability and functionality. These non-covalent, intermolecular forces working at several length and time scales define functional materials that may offer opportunities to tackle the challenges of sustainability. Such bio-inspired materials coming from a combination of synthetic polymer chemistry and chemistry inspired by nature form a future path to innovation and sustainable growth. They bring a basis for materials differentiation and renewed competitiveness in the chemical industry.

The accurate description of the rapidly changing viscoelastic character of the gas-laden polymer melt during the expansion phase of foam development is one of the main challenges in modeling thermoplastic foam processing. A general model addressing this challenge for amorphous and semi-crystalline polymers is presented here. Key model elements include the capturing of strain hardening in extensional flow and flow-induced crystallization. The extensional rheology is modeled using the Lodge constitutive equation. The crystallization is modeled using the Avrami equation enhanced with a flow-induced Jay-factor. The model is applied to two isotactic polypropylene materials. The results show the complex non-linearity of foam expansion. The calculated foaming window is in good agreement with experimental data.

One of the largest drainage programmes in the world was started in Egypt soon after completion of the High Aswan Dam in 1970. So far, about 2 2 10 6 ha of irrigated farmland in the Nile basin has been provided with subsurface drainage systems. In a country-wide monitoring and evaluation project, the effects of drainage on groundwater tables and soil salinity have been assessed and the impacts on yields and farm incomes determined. The results show that the drainage programme is an effective measure in controlling groundwater tables and salinity and a highly profitable investment for both the national economy and farmers.

Foaming of thermoplastic polymers is a complex process. Here models are presented that address the viscoelastic character of the thermoplastic melt during the expansion phase of foam development. Each cell is described as consisting of a spherical gas bubble surrounded by a spherical shell of polymer containing dissolved gas (see Figure).

Abstract The majority of LLDPE resins is processed via blown film extrusion techniques for various applications in the industrial and consumer packaging business. These LLDPE resins all have, independent of the molecular structure differences, the same intrinsic limitation in blown film extrusion processing. These limitations are: low output, high sensitivity to surface defects (stripes, sharkskin), high machine power requirement, need for large die gaps, lower bubble stability, and low melt strength. As a consequence, the more versatile—manufacturing and property wise—LLDPE resins are not used to their full potential. The industrial objective is therefore threefold: • develop a new LLDPE resin overcoming the above limitations, • develop a new flexible blown film extrusion line tailored to the new generation of LLDPE resins, • develop an efficient 3-D finite element simulation code to assist in the resin and blown film extrusion line development.

During the last two decades Accelerator Mass Spectrometry (AMS) has allowed major developments in many areas of geoscience and archaeology. It is projected that in the near future a similar potential for AMS is likely in the field of biomedical research leading, ultimately, to clinical applications. For such applications, the required instrumentation differs significantly from that presently used in the field of 14C dating. While the accuracy and sensitivity needed are more than an order of magnitude less demanding than that for present state-of-the-art 14C analysis, the availability of AMS spectrometers that are small, simple to operate and that are capable to handle CO2 samples is conditional upon a widespread acceptance of 14C AMS in biomedical research. In order to satisfy these demands, HVEE has developed a compact 14C AMS spectrometer dedicated to biomedical research. The instrument consists of a compact accelerator with a footprint of 2.25 × 1.25 m and an ion source that features direct CO2 acceptance and optimal user friendliness. The layout and the design of the accelerator was presented elsewhere [D.J.W. Mous, K.H. Purser, W. Fokker, R. van den Broek, R.B. Koopmans, Nucl. Instr. and Meth. B 123 (1997) 159]. In this contribution, we discuss the progress on the accelerator. Furthermore, the design and first results of the CO2 ion source are presented.

At high flow rates during polymer melt extrusion, pressure oscillations can be observed. The phenomenon is usually referred to as spurt, due to the irregular—in bursts—emergence of the melt out of the die. Spurt, or equivalently, the associated pressure oscillations have been modelled successfully through the mechanism of relaxation-oscillations by Molenaar and Koopmans. The presence of a non-monotone flow curve is at the heart of this modelling. In this paper the curve is deduced from conservation laws combined with a die wall boundary condition and specific constitutive equations. Subsequently, three `model curves' are compared. Model A, a Newtonian fluid with a `switch function' defining an alternating stick-slip boundary condition. Model B is a non-monotone constitutive equation i.e. a Johnson-Segalman-Oldroyd (JSO) fluid with a no-slip condition. Model C consists of two Newtonian fluids in concentric die regions and a no-slip condition. It is shown that Models A and C are able to describe spurt that is in qualitative agreement with experiments reported in literature. Model B, however, does not lead to spurt, in spite of the non-monotone nature of the steady stress–strain rate curve! These results tend to show that there are many options to describe experimental flow curves with equations based on geometrical, operational and polymer property parameters. Accordingly, from a mathematical point of view, and in view of the equivalence in results between model A and C, it can be concluded that the existing controversy between slip or no-slip (i.e. constitutive) supporters is not a fundamental one.

A quantitative model to describe capillary rheometer experiments is presented. The model can generate `two-branched' discontinuous flow curves and the associated pressure oscillations. Polymer compressibility in the barrel, incompressible axisymmetric generalised Newtonian flow in the die, and a switch curve that defines a stick-slip boundary condition are key elements in the model. Well defined experimental results of high density polyethylene are used to validate the model. The calculations compare well with the experiments. The only fit parameters are those related to the slip law. The present model can be made fully predictive by relating the slip law to fundamental polymer-wall interaction properties. The model offers a mathematical framework to validate potential slip laws.

During the last two decades the unparalleled sensitivity of accelerator mass spectrometry (AMS) has allowed major developments in many areas of geoscience and archeology. It is projected that in the near future a similar potential for AMS expansion is likely in the field of biomedical research leading, ultimately, to clinical applications. As an example of the growth of this new field, at the Lawrence Livermore National Laboratory Center for AMS the number of biomedical 14C measurements already represents a significant fraction of the total for all 14C. Widespread adoption of AMS in the biomedical field does require, however, the availability of instruments that are small in comparison with existing AMS systems and that will operate in a manner that is simple and user-friendly. To meet this demand, High Voltage Engineering Europa (HVEE) has developed a miniature, high-efficiency AMS instrument designed to provide for biomedical samples 14 C 12 C ratios with an accuracy better than 2% and with backgrounds limitations below 0.1 Modern. The current status of this program will be presented in the present paper.

Magnetic resonance imaging (MRI) was used to monitor cyclosporine therapy for chronic progressive multiple sclerosis in a multicenter clinical trial and an analysis was performed to determine whether there was a correlation between clinical changes and MRI changes. MRI was performed on 163 patients at the onset and completion of the 2–year study. Burden of disease (BOD, lesion load) was quantitated by a single observer using a computer program. Active lesions were also identified. The Expanded Disability Status Scale (EDSS) score was determined every 3 months. MRI data did not show any effect of cyclosporine treatment on BOD progression (mean 24.5% increase/yr) or lesion activity. However, there was a statistically significant positive correlation between the baseline total BOD value and the baseline EDSS score (r = 0.221, p = 0.005) and a positive correlation between the percent changes in BOD from baseline to exit and EDSS score (r = 0.186, p = 0.018). The study supports the concepts that MRI is a useful technique in monitoring therapeutic trials and that MRI is a direct measure of pathology.

The influence of flow rate and die geometry on the observable flow rate/pressure relationship of a linear high density polyethylene is investigated using a capillary rheometer. The experimental results are applied to an adapted version of the relaxation–oscillation model proposed by Molenaar and Koopmans for describing the oscillating flow regime. The current model allows for a quantitative description of the hysteresis cycle in the oscillating flow regime in terms of the main experimental variables, such as imposed flow rate, reservoir (barrel) volume, and material compressibility.

Magnetic resonance imaging (MRI) was used to evaluate the efficacy of systemic lymphoblastoid interferon therapy in chronic progressive multiple sclerosis. The clinical outcome of this trial has been reported previously. Thirty-six patients with chronic progressive multiple sclerosis were treated with interferon daily for 6 months and 27 received placebo. Patients had MRI at the outset of the study and after 6 and 24 months. Lesion activity and changes in lesion load were determined. As the study progressed, both the interferon- and the placebo-treated group developed more active lesions. There was no difference in lesion activity between the two groups. Comparison of lesion load, however, showed a trend toward improvement after 6 months for the interferon-treated group. This difference between the two groups had disappeared by the end of the study. We conclude that lymphoblastoid interferon was not effective in decreasing active MRI-detected lesions or in decreasing MRI lesion load in patients with chronic progressive multiple sclerosis.

Two high density polyethylene (HDPE) resins–samples 801 and 802–both nominally the same material, as they are taken from successive batches of the same commercial grade, are characterized for their molecular structure and rheological properties. Gel permeation chromatography (GPC) and low angle laser light scattering (LALLS) results must be interpreted in combination with rheological data to show the presence of somewhat more high molecular weight material in 802 that in 801. Small amplitude oscillatory shear, steady shear, and capillary shear measurements performed in different laboratories show consistently higher shear viscosity values at low shear rates for sample 802. Extensional viscosity measurements show similar results. The interpretation of rheological data in terms of molecular structure could be complicated by the possible presence of long chain branching (LCB). The zero shear viscosity and discrete relaxation spectrum is estimated for both samples. The small rheological difference between 801 and 802 forms the basic information for understanding their time dependent extrudate swell behavior, as will be described in Part II.

Two high density polyethylene resins—801 and 802— are examined with regard to their isothermal, time-dependent, and nonisothermal swelling properties when emerging from two annular and three diverging dies. The short time swelling characteristics of samples 801 and 802 are very important for these dies, resulting in a lower diameter swell for the latter, independent of the die geometry or flow rate. Output variations have much less impact on the swelling behavior than small changes in the geometry of the die mandrel. Accordingly, shear stress and shear rate parameters alone cannot be used to explain the swelling properties of a HDPE resin in the different die geometries. Straight annular dies induce higher diameter swelling than diverging dies.

For two high density polyethylene resins, the isothermal time dependency of extrudate swell has been measured. Very minor differences in the large molecular weight part of the molecular weight distribution, hardly detectable with gel permeation chromatography and low angle laser light scattering techniques, dramatically influence the time dependency of extrudate swell as well as the maximum swell attainable. The presence of larger molecules in sample 802 than in 801 is reflected in a lower short time (after seconds) and a larger long time (after minutes) or maximum extrudate swell value. Extruding the polymers through a capillary die L:D = 30:2 mm into air at ambient temperature allows only the short time swelling behavior to be observed, because cooling and sagging of the strand.

Earlier this year, a 'Dear Doctor' letter was sent to Dutch health care professionals, describing the rare occurrence of fulminant hepatitis and the Stevens-Johnson syndrome or toxic epidermal necrolysis in patients using moxifloxacin. This resulted in media attention, questions in parliament and moxifloxacin being banned from the formulary in several hospitals. Was this reaction justified? In the Netherlands, moxifloxacin is only mentioned in the practice guideline on the treatment of severe community-acquired pneumonia. Alternatives for moxifloxacin for this indication are penicillin combined with ciprofloxacin, or cephalosporins in combination with erythromycin. The associated risks, in particular fatal anaphylaxis and sudden cardiac death, of these combinations are substantially higher compared to the reported incidence of severe moxifloxacin-associated liver and skin toxicity. 'Dear Doctor' letters are important when new side effects become apparent, but these side effects must be placed in the overall balance of pros and cons of a drug as compared to the alternatives.

There is growing evidence that angiotensin II-receptor antagonists may have protective effects for preventing cerebrovascular incidents. --It is unlikely that these effects are due only to a decrease in blood pressure. --One hypothesis is that high concentrations ofangiotensin II result in improved cerebral perfusion ofangiotensin type 2-receptor mediated mechanisms such as local vasodilatation and angiogenesis. --Several clinical and preclinical studies support this hypothesis. --The results of these studies are discussed in this overview. There is still insufficient evidence that a protective effect on the brain occurs.

‘Een dwaas kan meer vragen dan tien wijzen kunnen antwoorden’, luidt het spreekwoord. Vragen stellen is blijkbaar gemakkelijker dan vragen beantwoorden. Dit geldt ook in de dagelijkse geneeskundige praktijk.

La variation des proprietes rheologiques provoquee par l'introduction de ramifications par irradiation du LLDPE sont en accord avec des resultats precedents obtenus avec le HDPE. La chromatographie gel combinee avec la diffusion laser centrale montre que la ramification est uniformement distribuee sur le domaine de masse moleculaire

The long-wave (lubrication) approximation governing the evolution of a thin film over a uniformly heated topographical substrate is solved numerically. We study the initial-value problem for a variety of governing dimensionless parameters and topographical substrates. We demonstrate that the dynamics is characterized by a slow relaxation process with continuous coarsening of drops up to a large time where coarsening is terminated and the interface organizes into a series of drops each of which is located in a trough in topography.

A 39-year-old woman was admitted with somnolence, severe hypertension and thrombotic microangiopathy. Both malignant hypertension and thrombotic thrombocytopenic purpura (TTP) were considered. Immediate therapy was instituted to treat both diseases because of severe clinical deterioration. Eventually, TTP was considered less likely due to the presence of grade IV hypertensive retinopathy (papilloedema and soft exudates) and a normal Von Willebrand factor-cleaving protease level. Differentiating TTP from malignant hypertension can be difficult as both diseases have similar clinical, laboratory and radiological features. In both diseases, hypertension, thrombotic microangiopathy and encephalopathy with white-matter lesions in the posterior regions of the brain may be apparent. Funduscopic abnormalities consistent with grade III and IV hypertensive retinopathy are rare in TTP, as are normal levels ofVon Willebrand factor-cleaving protease. Therefore, the diagnosis TTP was considered less likely and plasmapheresis was stopped. Hereafter, the laboratory values pointing towards haemolysis remained normal with adequate blood pressure control supporting the rejection of TTP as the cause of the symptoms.

A 30-year-old man known to have a factor-IX deficiency was presented at the emergency department with unexplained coma. After immediate treatment with factor IX, a CT-scan of the brain revealed no intracerebral haemorrhage. However, blood tests showed severe hyponatraemia, low serum osmolarity and high urine-sodium excretion consistent with the Syndrome of Inappropriate Antiduretic Hormone Secretion (SIADH). Therapy with hypertonic saline was instituted resulting in a gradual rise in the serum-sodium concentration. The cause of the hyponatraemia however remained unclear. After repeat history taking the patient mentioned the use of desmopressin for nocturia. Hyponatraemia as a complication of desmopressin use occurs in 8% of adult patients treated for nocturia. Direct availability of a patient's drug history, by means of an electronic record for instance, could avoid unnecessary tests and delay in diagnosis.

A 76-year-old woman with combined aortic and mitral valve disease presented with anaemia due to a gastric carcinoma. Further staging revealed no evidence for metastatic disease. Approval for surgery for the carcinoma was obtained after a cardiologist and anaesthesiologist were consulted. On the day of surgery, however, the attending anaesthesiologist estimated the operative risk to be unacceptable. The patient reversed her decision and decided not to have the oncological operation, as she felt well at the moment and considered the limited additional survival time not worth the anxiety. The expert opinion of an anaesthesiologist, a cardiologist and an oncologist not primarily involved in this case show that they differ as to the question who is responsible for the decision-making process in patients such as this one. The evidence on estimating operative risk in patients with cardiac valve disease undergoing noncardiac surgery is not unequivocal. Furthermore, there is a shared responsibility when more physicians are involved in the process of decision-making. Agreement on operative risk between physicians is necessary in order to prevent transfer of conflicting information to the patient.

A 27-year-old woman was admitted to the hospital with a depression, anaemia and fatigue. She had come from Angola to the Netherlands as a refugee 2 years before this evaluation. As an explanation for her symptoms tropical infectious diseases of parasitic origin were considered, but no clues were found in this direction. The test for trypanosomiasis was considered to be suggestive for an infection in the past (persistent titre 1:200). She was discharged but readmitted 6 months later because of a deterioration of her clinical condition. Magnetic resonance imaging showed bilateral signal abnormalities within the white matter of the brain. On examination no neurological signs or abnormalities were found. Again, no definite diagnosis could be made and the patient was discharged. Because of a further deterioration of her clinical condition she was readmitted a short time later for the third time. On the MRI the white matter lesions had increased. The serum protein electrophoresis was markedly abnormal with an elevated IgM Level. Finally, at a repeated lumbar puncture mobile trypanosomes were found. The diagnosis of 'West African sleeping sickness' was made and the patient was treated with eflornithine. She recovered completely during the next 18 months.

Refusal of food and/or fluids frequently occurs in nursing home patients. If the patient's decision to stop eating and drinking has been taken consciously and with due consideration of the consequences, it is referred to in Dutch as 'versterven'. A mentally competent, 73-year-old male nursing home patient suffering from progressive supranuclear palsy wished, in order to prevent further suffering, to end his life by taking sleeping tablets that he had saved up and by refusing artificial food and liquids. This wish met with a lot of legal and moral objections from the board of directors of the nursing home as well from experts consulted by the nursing home physician. Closer examination afterwards, however, showed that the patient would have been spared a lot of uncertainty if all parties concerned had been better informed as to the legal and moral framework. There are no legal objections as long as the doctors assess the refusal of food and drink with regard to voluntariness, deliberateness and permanence. If we as a society accept that mentally competent patients who are fully aware of the consequences and of possible alternative methods of treatment may take this road, then there would seem to be no moral obstacles either.

A 41-year-old man presented with unexplained bleeding from the right tonsil. He subsequently developed periodic fever, cervical lymphadenopathy and hepatosplenomegaly. Despite extensive bacteriological, serological and radiographic investigations for infectious disease, rheumatic disease and malignancy no diagnosis was made. Although the fever pattern was very suggestive of Pel-Ebstein fever--commonly associated with lymphoproliferative disease--multiple biopsies of lymph nodes, bone marrow, tonsils and liver all proved negative. Empirical glucocorticoid therapy gave some temporary improvement lasting for a month. Splenectomy or splenic biopsy was not carried out because of the risk of excessive bleeding. Eventually the patient died of multi-organ failure and sepsis. At autopsy, a T-cell lymphoma with an unusual phenotype and focal involvement of bone marrow, liver and spleen was found. Clinicians are sometimes faced with the dilemma of whether to perform multiple, invasive and possibly harmful diagnostic tests or to start empirical therapy. Empirical therapy may only be started if the diagnosis has been made on strong clinical grounds and, if this is not the case, only after further diagnostic tests. The question of whether a potentially harmful diagnostic test is justified depends on the clinical course, the sensitivity and specificity of the test and the therapeutic possibilities.

A 29-year-old female was admitted with fever, purpura and hemiparesis. She was treated for meningococcal sepsis after a Gram stain of a purpuric lesion showed Gram-negative diplococci. CT scan of the brain revealed multiple haemorrhagic lesions with obliteration of the sulci and basal cisterns. In the course of the disease she developed an acute myocardial infarction. Besides wall motion abnormalities, echocardiography revealed a bicuspid aortic valve with a vegetation on one of its cusps. Despite these findings, both the doctors who were involved in the treatment of this patient and the consulted physician in this article failed to reject the diagnosis 'meningococcal sepsis' and to replace it with a more likely diagnosis, namely Staphylococcus aureus endocarditis. The patient died one day after admission due to transtentorial herniation. Although purpuric lesions are common in meningococcal sepsis, they are not specific for this disease. The false-positive result of the Gram stain resulted in a process known as 'premature closure': the diagnosis of meningococcal sepsis was accepted before it was fully verified. In this case, the consequence was that other diagnostic tests and symptoms were misinterpreted with the result that inappropriate antibiotic therapy was instituted.

This paper describes work carried out in order to match experimental processing flows to numerical simulation. The work has brought together a consortium that has developed reliable experimental methods by which processing flows can be achieved in the laboratory and then ranked against numerical simulation. A full rheological characterisation of a selected range of polymers was made and the results compared from different laboratories. The data was fitted to a number of rheological models. Multi-mode parameter fitting was universal for the linear viscoelastic response. Particular attention was paid to the non linear response of the material. Prototype industrial flow experiments were carried out for a number of geometries in different laboratories and the flow birefringence technique was used to map out the experimentally observed stress fields for different polymers in a range of complex flows that contained both extensional and shear flow components. Numerical simulation was carried out using a number of algorithms and a range of constitutive equations. In order to make a quantitative comparison between experiment and simulation, an Advanced Rheological Tool (ART) module was developed that was able in some cases to quantify the level of fit between the numerically predicted and the experimentally observed stress patterns. In addition the ART module was able to optimise certain non-linear parameters in order to improve the quality of fit between experiment and simulation.

A 42-year-old woman was hospitalised due to recurrent fever (40 degrees C) and bacteraemia. A physical examination revealed no abnormalities. Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca and Enterococci were found in blood cultures. Laboratory results revealed liver enzyme levels which were only slightly elevated. An X-ray investigation, ERCPs, CT scans, ultrasounds, a leucocyte scintigram and a gallium scan, all revealed no abnormalities. Due to the results from the blood cultures it was thought that the bile duct system or the digestive tract were the focus of infection. Therefore a liver biopsy was carried out for the purpose of making a diagnosis. The patient was diagnosed as having ductal plate malformation, a microscopic congenital cystic dilatation of the bile ducts. The prognosis is poor and the treatment consists of lifelong antibiotics.

The low bioavailability of albendazole affects the therapeutic response in patients with echinococcosis. Cimetidine co-administration is reported to improve bioavailability. To analyze the assumed dose-dependent bioavailability of albendazole, we administered 5 to 30 mg/kg albendazole to 6 male volunteers in a randomized cross-over study. To assess the effect of cimetidine (10 mg/kg twice daily), the drug was given with albendazole (20 mg/kg). A dose-dependent bioavailability was not observed. This was due to inter-individual variability of the maximal concentration (Cmax 38%-72%) of albendazole sulphoxide (ABZSX), the active metabolite of albendazole. Cmax was 0.21+/-0.14 mg/L after 5 mg/kg and 0.39+/-0.19 mg/L after 30 mg/kg albendazole (P = 0.217). Cimetidine tended to decrease Cmax by 52% (P = 0.109) and significantly inhibited ABZSX breakdown as indicated by the prolongation of ABZSX elimination half-life from 7.4+/-3.3 hr to 19.0+/-11.7 hr (P = 0.028). Remarkably, the inter-individual variability of Cmax was significantly lower during cimetidine co-administration: 14% versus 72%.

A 20-year old man was admitted to hospital with fever and malaise after travel to India. He was soon found to have typhoid fever, caused by a multi-drug resistant Salmonella typhi. According to in-vitro resistance testing he was treated with cefotaxim, but fever and shivering were still present after 7 days of cefotaxim, with liver enzyme disturbances. The physicians caring for him started an extensive search for possible complications of typhoid fever, and they thought of the possibility of an alternative disease to explain the fever. When cefotaxim was stopped all symptoms and signs disappeared. During every medication, drug fever is a possibility. This diagnosis can only be supported by discontinuing the use and if necessary, restarting it (dechallenge and rechallenge).

This article presents characteristics and co-morbidity of patients with Korsakoff's syndrome after admission to a nursing home. The medical charts were studied of all patients with Korsakoff's syndrome, admitted between 1984 and 1998 to the special ward for Korsakoff patients of a nursing home in the eastern part of the Netherlands. The 'Standard of classification for diseases in nursing homes' ('Standaard van classificatie voor ziekten in de verpleeghuisgeneeskunde') was used to classify co-morbidity. The group included 77 patients. Almost 75% were male. The average age was 53 years on admission. More than 50% of the patients were divorced. After admission, 30% of the group was transferred to a different setting. The estimated average follow-up period was 7.1 year. Patients had 2.9 co-morbid conditions at admission. Diseases due to alcoholism were frequently diagnosed. During the stay skin diseases, psychological disorders and behavioural disorders were frequently noticed. The prevalence of cognitive impairment and alcohol dementia was surprisingly high. Thirteen patients died, most of them of cancer or combined cardiovascular and respiratory diseases. We conclude that patients with Korsakoff's syndrome are an unexplored area in nursing homes. This group of nursing home inhabitants shows its own characteristics and co-morbidity.

A 74-year-old man was admitted to hospital because of jaundice and malaise of several weeks' duration. Five years earlier he had sustained a stroke from which he had recovered almost completely. On physical examination he was overweight and had an enlarged liver. Laboratory values were consistent with cholestasis and hepatitis. An abdominal ultrasound showed multiple nodular abnormalities in the liver consistent with a malignancy. Rapidly developing abnormalities in blood coagulation were thought to be a contraindication to hepatic biopsy. The patient deteriorated and sustained a new stroke. The physicians were convinced that he had cancer and could not be cured. They planned further diagnostic studies, but at the same time made an advance directive for non-resuscitation. Three days after admission the patient was found dead; no consent for an autopsy was obtained. If it is suspected that a patient is suffering from a malignant disease, the malignancy should be demonstrated or excluded as quickly as possible in the least uncomfortable way. Also, the patient and his family should be informed of any restriction on the possibilities of treatment.