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Heat pump cycles with zeotropic mixtures as working fluids and temperature glides on both heat sink and heat source sides are analyzed. Five binary zeotropic mixtures, selected based on previous studies in the literature, are examined. The cycles are initially optimized for each binary mixture at three different heat source temperature glides (10–30 K) and fixed heat sink temperature glide (30 K). The variation in the heating COP of the optimized designs is then computed and compared for five different part load scenarios down to 40% of the design point heating load. The design point optimization is performed for different single and double-compression cycle layouts, based on which the standard vapor compression cycle with a suction gas heat exchanger is adopted as the most economical option for the rest of the study. The part load cycle simulations demonstrate that, when the heat source temperature glide is large, two of the studied part load scenarios can lead to increased COP; these are when the reduction in the heating load is due to (1) an increase in both the heat sink (e.g. district heating water) inlet and heat source (e.g. process water) outlet temperatures, and (2) a decrease in both heat sink and source flow rates. Moreover, it is observed that different mixtures show different levels of sensitivity to a decrease in heating load. Among the studied mixtures, DME/Iso-Pentane while outperforming others in all studied cases, has the most unfavorable trend at part load, hence losing its benefit margin over other candidates.

The paper investigates the accuracy of scale perception in Virtual Reality (VR) for visualization of urban scale environments. Specifically, we evaluate users’ scale estimation accuracy by subjecting them to an urban scale environment using two different viewing modes: 360° monoscopic panoramas viewed in a VR headset, versus a full stereoscopic 3D VR representation, also in a VR headset, allowing participants to move around. The paper explores various aspects of this, including both ego- and exo-centric distance estimation, perception of own height, and photographic realism of 360° modes. The main experimental result is that, somewhat surprisingly, user distance estimation accuracy is higher in the monoscopic 360° viewing modes than in 3D VR; in 3D VR participants on average underestimate distances by around 20%. Nevertheless, participants on average feel significantly taller than normal in the 360° modes, whereas they feel normal height in 3D VR mode. We conclude that more work is needed in order to properly understand the perceptual and cognitive mechanisms behind scale perception in VR.

In this paper, we investigate the influence of texture fidelity on spatial perception in a standalone virtual reality application. To investigate this, we implemented a detailed virtual representation of an actual physical environment, namely a small one-bedroom apartment. The virtual apartment representation was tested in two differentvisual styles: high fidelity realistic textures, and a ”paper model” texture. Some test subjects experienced the virtual models using the actual physical apartment as transitional environment, other subjects experienced the model at an unrelated physical location. The environments were evaluated with 20 participants aged 20 to 61and results indicated a systematic overestimation of distances in virtual reality for all conditions. The results showed that a higher texture fidelity had a positive influence on precision but no significant influence on accuracy.It was also showed that transitional environments negatively influenced precision, but had no significant influence on accuracy. Self assessments of presence from the experiment supported previous claims about a correlation between the level of detail in an environment and presence, but not a correlation between presenceand distance perception.

A trend of distance underestimations in Virtual Reality (VR) is well documented, but the reason still remains unclear. Therefore, this paper investigates the effect of differently sized Virtual Environments (VEs) on egocentric distance perception in VR as a potential influence. Verbal assessment, blind walking, and our own proposed method: walk and assess, were compared in an experiment, and blind walking was found to be the most accurate. A virtual replica of a real-life location was created as a transitional environment, while small (15m2), medium (35m2) and large (95m2) rooms were created to investigate the effect of VE size on spatial perception in VR. To establish the differences in estimations between the real world and VR when using blind walking, a study was conducted with the virtual replica and its real life counterpart at distances between 1 and 10 meters. Following this, the three distinct room sizes were used in an experiment to investigate the effect of the size of rooms on spatial perception in VR. The findings showed consistent underestimates of distances, and a trend for underestimation to grow as the distance grows was observed. Similarly, underestimates grew with the size of the environment.

Large-scale ammonia refrigeration and heating systems have been widely used in industry due to their high efficiency, broad temperature ranges of operation and innocuous environmental effects. However, implementation of this technology in small to medium systems has not yet been very successful. Factors like the toxicity of the refrigerant and prices of ammonia equipment are some of the obstacles that this technology must overcome before being able to enter a market dominated by systems running on HFC refrigerants. This paper presents a concise review of the research and development of ammonia systems designed to supply small to medium capacity applications. Based on this review, a low charge ammonia chiller and heat pump unit intended to supply both needs providing 180 kW of cooling and 200 kW of heating was proposed. A market overview was performed to find the available equipment that can guarantee proper operation with the lowest possible refrigerant charge. Furthermore, a numerical study of three concepts for this system was performed to study the performance, as well as refrigerant charge estimation and distribution within the equipment. The analysis laid the foundation to propose a suitable configuration to embrace the intended market segment not only considering the high coefficient of performance but also specific refrigerant charge.

Background: Inconclusive bone scans are a challenge but there is no consensus about follow-up imaging. We evaluated the use of 68gallium-labelled prostate-specific membrane antigen (68Ga-PSMA) PET/CT if 18F-sodium fluoride (18F-NaF) PET/CT was inconclusive. Methods: This retrospective study included patients with no previously known bone metastases who had one or more equivocal bone lesions on 18F-NaF PET/CT and underwent additional 68Ga-PSMA PET/CT. The bone lesions were deemed as true metastases or not based on follow-up by surveying supplemental imaging modalities and hospital records. A subgroup of patients with “most valid follow-up” was created, which included patients with unmeasurable PSA after prostatectomy or subsequent imaging (additional 18F-NaF PET/CT, 68Ga-PSMA PET/CT, CT, or MRI). Results: Of the 2918 patients referred for 18F-NaF PET/CT from the department of urology in the inclusion period, 51 (1.7%) were inconclusive regarding bone metastases and underwent additional 68Ga-PSMA PET/CT. Thirteen of these patients (25%) were ultimately diagnosed with bone metastases. Patient-based sensitivity, specificity, and accuracy of additional 68Ga-PSMA PET/CT were 100%, 95%, and 96%, respectively. In patients with “most valid follow-up”, the same parameters were 100%, 93%, and 94%, respectively. Conclusion: 68Ga-PSMA PET/CT is an excellent complementary modality in when 18F-NaF PET/CT is equivocal.

The present study demonstrates the optimization of a heat pump for an application with a large temperature glide on the sink side and a smaller temperature glide on the source side. The study includes a numerical simulation of a heat pump cycle for binary mixtures based on a list of 14 natural refrigerants. This approach enables a match of the temperature glide of sink and source with the temperature of the working fluid during phase change and thus, a reduction of the exergy destruction due to heat transfer. The model was evaluated for four different boundary conditions. The exergy destruction due to heat transfer, which is solely caused by the fluid having a non-ideal temperature profile was quantified and an indicator describing the glide match was defined to analyze its influence on the performance. The results indicated, that a good glide match can contribute to an increased performance. The increase in performance was dependent on the boundary conditions and reached up to 20% for a simple cycle and up to 27% if the superheating can be avoided. The temperature glide match in the source was identified to have a higher influence on the performance than in the sink.

OBJECTIVES: To determine the diagnostic accuracy of 68gallium prostate-specific membrane antigen (PSMA)-based positron emission tomography/computed tomography (PET/CT) in comparison with 18F-fluoride-based PET/CT (NaF-PET/CT) and whole-body magnetic resonance imaging (WB-MRI) for the detection of bone metastases in patients with prostate cancer.METHODS: Sixty patients with prostate cancer were included in the period May 2016 to June 2017. The participants underwent three scans (index tests) within 30 days: a NaF-PET/CT, a WB-MRI and a PSMA-PET/CT. Experienced specialists assessed the scans. In the absence of a histological reference standard, the final diagnosis was determined as a panel diagnosis. Measures of the diagnostic performances of the index tests were calculated from patient-based dichotomous outcomes (0 or ≥ 1 bone metastasis) and pairwise compared (McNemar test). For each index test, the agreement with the final diagnosis with regard to the number of bone metastases detected (0, 1-5, > 5) and the inter-reader agreement was calculated (kappa coefficients).RESULTS: Fifty-five patients constituted the final study population; 20 patients (36%) were classified as having bone metastatic disease as their final diagnosis. The patient-based diagnostic performances were (sensitivity, specificity, overall accuracy) PSMA-PET/CT (100%, 100%, 100%), NaF-PET/CT (95%, 97%, 96%) and WB-MRI (80%, 83%, 82%). The overall accuracy of PSMA-PET/CT was significantly more favourable compared to WB-MRI (p = 0.004), but not to NaF-PET/CT (p = 0.48). PSMA-PET/CT classified the number of bone metastases reliably compared to the final diagnosis (kappa coefficient 0.97) and with an "almost perfect" inter-reader agreement (kappa coefficient 0.93).CONCLUSIONS: The overall accuracy of PSMA-PET/CT was significantly more advantageous compared to WB-MRI, but not to NaF-PET/CT.KEY POINTS: • PSMA-PET/CT assessed the presence of bone metastases correctly in all 55 patients • PSMA-PET/CT was more advantageous compared to WB-MRI • No difference was found between PSMA-PET/CT and NaF-PET/CT.

Background For decades, the most widely used imaging technique for myeloma bone lesions has been a whole-body skeletal X-ray survey (WBXR), but newer promising imaging techniques are evolving. Purpose To compare WBXR with the advanced imaging techniques 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT), 18F-sodium fluoride (NaF) PET/CT and whole-body magnetic resonance imaging (WB-MRI) in the detection of myeloma bone lesions. Material and Methods Fourteen patients with newly diagnosed multiple myeloma were prospectively enrolled. In addition to WBXR, all patients underwent FDG-PET/CT, NaF-PET/CT, and WB-MRI. Experienced specialists performed blinded readings based on predefined anatomical regions and diagnostic criteria. Results In a region-based analysis, a two-sided ANOVA test showed that the extent of detected skeletal disease depends on the scanning technique ( P Conclusion WB-MRI detects on average significantly more body regions indicative of myeloma bone disease compared to WBXR, FDG-PET/CT, and NaF-PET/CT. The lack of significance in the patient-based analysis is most likely due to the small number of study participants.

The performance of a heating system consisting of a heat pump with an integrated storage tank was evaluated by means of Computational Fluid Dynamics (CFD) calculations. The aim of the investigations was to elucidate how thermal stratification in the tank would influence the COP of the system. Differently designed storage tanks were investigated under typical operation conditions. CFD models of heat storage tanks were developed and validated by experiments on a test tank. Calculations with the validated models were carried out in order to find the optimal tank design and system settings for achieving the highest possible COP. The investigated parameters were volume flow rate, tank geometry, diffuser design and tank wall material. Two different system COPs were defined: one based only on charge operation and the other on both charge and discharge operations. It was found that there is a direct connection between the thermal stratification inside the tank and the COP of the heating system. Higher degree of stratification leads to higher COP. For the ideal case where there is no mixing, no vertical thermal conduction in the tank and no heat loss from the tank, the system COP after a charge-discharge cycle is 3.69. When the effect of mixing is taken into account, the obtained COP of the system is decreased by approximately 9%. If heat transfer to the tank wall and vertical thermal conduction are also taken into account, the obtained system COP is lowered by another 5%. Moreover, the COP of a heating system with high flow rates can be significantly increased by a diffuser plate installed in the tank with a small distance to the inlet/outlet. The best performing system studied consisted of an insulated tall and slim tank with a h/d ratio of 3.64 and a perforated plate diffuser, giving a COP of 3.23 which was 32% higher compared to a case without a diffuser. The performance of the suggested system was not affected by variations of flow rates in the range from 0.12 to 0.24 kg/s.

The present study demonstrates the optimization of a heat pump for an application with a large temperature glide on the sink and a smaller temperature glide on the source side. The study includes a simulation of a heat pump cycle for all possible binary mixtures from a list of 14 natural refrigerants, which enables a match of the temperature glide of sink and source with the temperature of the working fluid during phase change and thus, a reduction of the exergy destruction due to heat transfer. The model was evaluated for four different boundary conditions. For a separated evaluation of the irreversibility solely caused by the fluid properties, the exergy destruction in the heat exchangers has been distinguished accordingly and an indicator quantifying the glide match has been defined to analyse the influence on the performance. It was observed that a good glide match can contribute to an increased performance. Dependent on the boundary conditions a performance increase of 20.0 % for a simple cycle was observed and 26.9 % increase if the required superheating can be avoided. The temperature glide match in the source was identified to have a higher influence on the performance than in the sink.

We prospectively evaluated and compared the diagnostic performance of

Det er skolens ledelse, der må sikre, at lærerne arbejder professionelt med den pædago-gisk-didaktiske praksis. Forudsætningen for, at man kan vurdere, om dette er tilfældet eller ej, er, at man på skoleniveau evaluerer på lærernes praksis. Som leder har man ansvaret for at vurdere lærernes præstationer og kompetencer med henblik på lærernes udvikling og læring som fagprofessionelle, på samme måde som lærerne skal (være i stand til at) understøtte og vurdere elevernes præstationer og læringsudbytte af undervisningen. Læ-rerne skal også medvirke og dermed evaluere sig selv forud for den fælles dialog omkring vurdering af kompetenceudviklingsbehov og -tiltag. Hvordan kan man varetage den komplekse opgave at lede lærernes udvikling og læring? Artiklen formidler nogle bud på, hvordan denne ledelsesopgave kan håndteres gennem systematisk evaluering af lærernes kompetencer, dialog, feedback og individuelle udviklingsplaner. Artiklen henvender sig til ledere (og lærere) både i folkeskolen og på ungdomsuddannelserne. Den kunne formentlig også være til inspiration for ledere og lære-re i andre skoleformer. Den henvender sig i nogen grad også til de øverste chefniveauer for skolerne som inspiration til, hvad der kunne være behov for at understøtte i forhold til implementering i praksis., CEPRA-striben, Nr. 14 (2013): Feedback

Levetiracetam is an anticonvulsant which is assumed to act by modulating neurotransmitter release via binding to the vesicle protein SV2A. This could have an impact on signalling in the pain pathway. The aim of this study was to test the analgesic effect of levetiracetam in central pain in multiple sclerosis. This was a randomized, double-blind, placebo-controlled, cross-over trial with levetiracetam 3000 mg/day versus placebo (6-week treatment periods). Patients with multiple sclerosis, symptoms and signs complying with central neuropathic pain and pain symptoms for more than 6 months, as well as pain intensity of more than 4 on a 0 to 10-point numeric rating scale were included in the study. The primary outcome measure was pain relief at the end of each treatment period as measured on a 6-point verbal scale. Eighty-nine patients were screened for participation and 30 patients entered the study. Twenty-seven patients were included in the data analysis. There were no differences in the ratings of pain relief (levetiracetam 2.4 vs. placebo 2.1, p = 0.169), total pain intensity (levetiracetam 5.3 vs. placebo 5.7, p = 0.147) or any of the other outcome measures (p = 0.086-0.715) in the total sample of patients. However, there was significant reduction of pain, increased pain relief and/or more favourable pain relief with levetiracetam than with placebo in patients with lancinating or without touch-evoked pain (p = 0.025-0.046). This study found no effect of the anticonvulsant levetiracetam in non-selected patients with central pain in multiple sclerosis, but an effect in subgroups with specific pain symptoms was indicated.

Myocardial perfusion imaging (MPI) holds an important place as non-invasive risk assessment in patients with intermediate risk of coronary heart disease (CHD). However, as much as 60-70% of MPI scans are normal. This study evaluates the role of coronary artery calcium scoring (CAC score) and NT-proBNP as potential gatekeepers for MPI. Patients with intermediate risk of CHD referred for standard MPI were included. CAC score and NT-proBNP were both assessed at the day of the stress study. Sensitivity, specificity and NPV for prediction of abnormal MPI scans were calculated for CAC, NT-proBNP and the combination hereof. A total of 190 patients were included (mean age 61 ± 12 years, 55% female) of whom 24% had known CHD. In all 30% of the scans were abnormal. CAC score achieved the highest AUC regardless of whether patients with known CHD were included or not [AUC 0·75 95% CI (0·66-0·84) and AUC 0·79 (0·68-0·91)]. As a singular variable, CAC score was the most potent predictor with a sensitivity of 85%, specificity of 39% and NPV 88%. The combination of CAC score10 and NT-proBNP26 reached a sensitivity of 98% and NPV 94%, where 8% of scans tentatively could be avoided. In patients referred for MPI with intermediate risk for CHD, a combination of CAC score and NT-proBNP could be used to identify a group of patients where MPI could be averted with a high degree of diagnostic safety.

In humans, maternal hypercholesterolemia during pregnancy promotes microscopical fatty streaks in the children. The mechanism is unknown. Fatty streaks are clinically silent, and many of them regress and never develop into advanced atherosclerosis. The aim of this study was to investigate whether hypercholesterolemia in pregnant mice induced more advanced atherosclerosis in their adult progeny. Hypercholesterolemic (HC) apolipoprotein E knockout (apoE(-/-)) female mice were mated with normocholesterolemic (NC) wild-type (apoE(+/+)) males and vice versa. All parents were almost identical genetically except for apoE. Therefore, all progeny became genetically identical and heterozygous apoE(+/-). They were born of either HC (i.e. apoE(-/-)) or NC (i.e. apoE(+/+)) mothers. The progeny were killed 6 months after birth and the amount of atherosclerosis in the aortic root was assessed. Females developed more atherosclerosis than males (P

Background: Tricyclic antidepressants (TCA) are often used in the treatment of painful polyneuropathy. Venlafaxine is a serotonin and weak noradrenaline reuptake inhibitor antidepressant with a different profile of other pharmacologic actions from those of TCA. Objective: To test if venlafaxine would relieve painful polyneuropathy and compare its possible efficacy with that of the TCA imipramine. Methods: The study design was randomized, double blind, and placebo controlled, with a three-way crossover. Forty patients were assigned to one of the treatment sequences, and 29 completed all three study periods. The daily doses were venlafaxine 225 mg and imipramine 150 mg. During the three treatment periods, each of 4 weeks’ duration, patients rated pain paroxysms, constant pain, and touch- and pressure-evoked pain by use of 0- to 10-point numeric rating scales. Results: The sum of the individual pain scores during treatment week 4 was lower on venlafaxine (80% of baseline score; p = 0.006) and imipramine (77%; p = 0.001) than on placebo (100%) and did not show any statistical difference between venlafaxine and imipramine ( p = 0.44). The individual pain scores for pain paroxysms, constant pain, and pressure-evoked pain showed a similar pattern, whereas touch-evoked pain was uncommon and was not altered by any of the drugs. Numbers needed to treat to obtain one patient with moderate or better pain relief were 5.2 for venlafaxine and 2.7 for imipramine. Conclusion: Venlafaxine relieves pain in polyneuropathy and may be as effective as imipramine.

This paper presents a study of modelling desuperheating in ammonia heat pumps. Focus is on the temperature profile of the superheated refrigerant. Typically, the surface area of a heat exchanger is estimated using the Log Mean Temperature Difference (LMTD) method. The assumption of this method is that the specific heat is constant throughout the temperature glide of the refrigerant in the heat exchanger. However, considering ammonia as refrigerant, the LMTD method does not give accurate results due to significant variations of the specific heat. By comparing the actual temperature profiles from a one-dimensional discretized model with the LMTD, it is found that the LMTD method provides a higher temperature difference than the discretised model, and would therefore lead to an underestimation of the needed condenser area. The lower temperature difference in the discretized model can be compensated for in two ways. The area of the heat exchanger can be increased or the condensation temperature can be raised to achieve the same temperature difference for the discretized model as for the LMTD. This would affect the compressor work, hence the COP of the system. Furthermore, for higher condenser pressure, and thus higher pressure in the desuperheater, a larger deviation between the two temperature difference models is observed. Using the discretization model the number of discretizations to get accurate estimates is found to be 20.

We assessed the diagnostic yield of adding quantitative sensory testing to the standard work-up for polyneuropathy in unselected patients. All patients aged 18 to 70 years referred to our department for electrodiagnosis with a tentative diagnosis of polyneuropathy and symptoms complying with predefined criteria were included in the study. We performed near nerve conduction studies in 4 nerves and determined heat and cold detection thresholds on hand and foot with a Thermotest (Somedic AB, Sweden). In order to uncover CNS diseases, somatosensory-evoked potentials were recorded in patients with abnormal quantitative sensory testing and normal nerve conduction studies. A total of 198 patients completed the study and 149 were considered to have polyneuropathy. Twenty-five patients remained undiagnosed and in 24 patients, other diseases were responsible for the symptoms. Of the patients with either polyneuropathy or no other diagnosis, 76% (n = 174) had abnormal nerve conduction. Abnormal cold sensation, heat sensation or abnormality in at least 1 of these and normal nerve conduction were found in 14, 12 and 17 patients. Of the 174 patients, 86% (95% CI 80-90%) had an abnormality in at least 1 of the tests (i.e. abnormal nerve conduction and/or abnormal quantitative testing of temperature sensation). In conclusion, quantitative testing of temperature sensation improves the diagnostic yield in patients examined for chronic polyneuropathy.

Tricyclic antidepressants are the mainstay of treatment of painful polyneuropathy but cannot be used in a substantial number of patients. St. John's wort is a herbal antidepressant, which may act via mechanisms similar to the tricyclics. The aim of this study was to test if St. John's wort would relieve painful polyneuropathy. The study design was randomized, double-blind, placebo-controlled and cross-over. Fifty-four patients were assigned to one of the two treatment sequences. The daily dose of St. John's wort was three tablets each containing 900 microg totalhypericin. During the two treatment periods of 5 weeks duration, patients rated constant pain, lancinating pain paroxysms, touch-evoked pain and pain on pressure by use of 0--10 point numeric rating scales. Forty-seven patients -- 18 diabetics and 29 non-diabetics -- completed the study. There was a trend of lower total pain score (sum of the individual pain scores) on St. John's wort than on placebo (median 14 vs. 15, P=0.05). None of the individual pain ratings were significantly changed by St. John's wort as compared to placebo (P=0.09--0.33). Complete, good or moderate pain relief was experienced by nine patients with St. John's wort and two with placebo (P=0.07). In conclusion, St. John's wort has no significant effect on pain in polyneuropathy.

We discuss possible mechanisms for setting up a global outreach campaign centred on the main theme of this meeting: save our skies! Effective communication of this message to the world's media and the wide public is a prerequisite for successful sensitisation of decision-makers in different countries to the crucial issues at stake. We emphasise the need for careful planning of such a programme, especially in terms of definition of the key issues, the way they are presented, as well as the communication channels to be employed. It is important to differentiate the arguments used in connection with different types of pollution (light, radio, space debris). It will be necessary to identify clear and forceful messages that convincingly stress that these problems are of ultimate concern, not just a small group of astronomers, but to all of humanity. With their extremely sensitive instruments, astronomers constitute an avant-garde that is the first to detect the adverse effects, but as these intensify, increasingly broader sectors of society will be affected. It appears feasible, within the limited means available to the IAU and IDA, to initiate such an outreach effort with a comprehensive web-based campaign that highlights astronomical “pollution”. This may also serve as a useful test-bench for subsequent campaigns based on more communication vehicles and with a wider spectrum of associated activities.

ZSM-5 zeolites prepared by confined space synthesis, i.e., by crystallization inside a mesoporous matrix, are characterized by X-ray powder diffraction (XRPD), ammonia temperature-programmed desorption (TPD), 27Al and 29Si-MAS NMR spectroscopy, and transmission electron microscopy (TEM). It is shown by XRPD that confined space synthesis can be used for the preparation of pure and highly crystalline ZSM-5 with a uniform crystal size distribution governed by the pore size of the inert matrix. Ammonia desorption demonstrates that the small zeolite crystals have the same number of acid sites as large crystals when the Si/Al ratio is similar. The number of acid sites have been determined by ammonia TPD and converted into framework Si/Al ratios. These ratios are higher than the bulk Si/Al ratios but agree with those obtained from 27Al/29Si-MAS NMR. Furthermore, the 27Al MAS NMR spectra show that the synthesis conditions are important in order to prevent the formation of non-framework Al and that the best result is obtained using NaAlO2 as the aluminum source. By proper control of the synthesis conditions, it is possible to produce a ZSM-5 zeolite with a framework Si/Al=50 and without non-framework aluminum. The relative numbers of Si*(OSi)4, HOSi*(OSi)3, and AlOSi*(OSi)3 units have been determined from 29Si-MAS NMR in combination with the Si/Al ratios from 27Al-MAS NMR. These results indicate a higher number of HOSi*(OSi)3 sites for ZSM-5 zeolites of the nm size when compared to those of the μm size. Transmission electron micrographs provide independent support for the formation of small zeolite crystals.

Progressive multifocal leucoencephalopathy (PML) is a rarely occurring demyelinating disease of the central nervous system caused by a neurotropic papovavirus named JC virus (JCV). The most frequently affected affected regions are the cerebral hemispheres, especially the parietooccipital region, followed by the cerebellum and brain stem. The disease occurs predominantly in individuals with an immunocompromised state and impaired cellular mediated immunity (CMI) due to other underlying illness. More extensive use of irradiation and immunosuppressive therapy in relation to increased transplantational activities as well as treatment of autoimmune diseases and malignancies, in addition to the appearance of the acquired immunodeficiency syndrome (AIDS) as a consequence of infection with the human immunodeficiency virus (HIV), has caused a considerable increase in the occurrence of PML. The course of the disease is still most often rapidly progressive and fatal, but several cases with prolonged survival and even remission have been reported, and various antiviral treatments have been tried. The only drug that until now has shown favourable results is cytosine arabinoside. In HIV-infected PML-patients immunomodulation with AZT/zidovudine may alleviate the course and improve the prognosis in some patients. Suspicion of PML should lead to an extensive immunological investigation before considering of brain biopsy, which is still the only specific test. On the basis of the increased frequency of PML in relation to HIV-infection, it is likely that our knowledge of the pathogenetic aspects will increase, which, hopefully, may lead to an effective therapeutic strategy.

Objective Single-head gamma camera renography has been used for decades to estimate kidney function. An estimate of the glomerular filtration rate (GFR) can be obtained using Tc-diethylenetriaminepentaacetic acid (Tc-DTPA). However, because of differing attenuation, an error is introduced when the kidney depth or kidney size is unequal. This error can be reduced using geometric mean data obtained from dual-head renography. The aim of this study was to compare single-head versus dual-head assessment of single kidney function. Methods Thirty-four patients were examined with (a) single-head renography, acquiring counts from the left ventricle and kidneys from a posterior projection, and simultaneously with (b) dual-head renography, acquiring counts from the left ventricle from an anterior projection and kidneys from both anterior and posterior projections using geometric mean values. Single kidney GFR from both models was estimated (GFRcam1 and GFRcam2, respectively) and compared with GFR determined with plasma samples of Tc-DTPA (GFRps). Results The prediction intervals of GFRcam1 and GFRcam2 compared with GFRps did not differ significantly (SD of GFRcam1-GFRps=17.6 ml/min and SD of GFR2-GFRps=15.5 ml/min; P=0.48). The corresponding coefficients of variation were 16.5 and 14.7%, respectively. Conclusion There is no difference in variance between GFR estimated from single-head renography and that estimated using dual-head renography. Hence, dual-head camera renography might be useful in daily practice with the potential to provide a better estimate of absolute function in each kidney and the relative kidney function in patients with differing kidney depths and/or malformed kidneys.

A stereological estimation of nuclear volume in benign and atypical meningiomas was made. The aim was to investigate whether this method could discriminate between these two meningeal neoplasms. The difference was significant and it was moreover seen that there was no overlap between the two groups. The results demonstrate that atypical meningiomas can be distinguished from benign meningiomas by an objective stereological estimation of nuclear volume.

Confined space synthesis is a novel method in zeolite synthesis. It involves crystallization of the zeolite inside the pore system of an inert mesoporous matrix. In this way it is possible to prepare nanosized zeolites with a controlled size distribution by proper choice of the inert matrix. Here, confined space synthesis was adopted to prepare nanosized ZSM-5, zeolite Beta, zeolite X, and zeolite A with tailored crystal size distributions using mesoporous carbon blacks as inert matrices. All zeolites were characterized by X-ray powder diffraction, transmission electron microscopy, and nitrogen adsorption/desorption prior to and after removal of the carbon matrix. ZSM-5 with Si/Al ratios of 50, 100, and infinity (silicalite-1) were synthesized with controlled average crystal sizes in the range 20-75 nm. Nanosized zeolite Beta (7-30 nm), zeolite X (22-60 nm), and zeolite A (25-37 nm) were prepared similarly. Removal of the carbon matrix by controlled combustion allows a convenient method for isolation of the pure and highly crystalline zeolites. Therefore, confined space synthesis appears to be an attractive method for preparation of zeolites with a controlled size distribution.

L’Europe, pionniere en astronomie au siecle des lumieres, s’est trouvee en difficulte face a la competition des Etats-Unis au XXe siecle. En reponse a ce defi, pression financiere et constructions d’infrastructures modernes de recherche ont amene la communaute scientifique europeenne a se concerter et a s’organiser, bien au-dela d’une simple mise en place d’une nouvelle « machine » de recherche. Catherine Cesarsky et Claus Madsen expliquent comment l’Europe de l’astronomie au sol a su abolir les frontieres et se federer en creant et developpant l’Observatoire europeen austral (ESO).

Objective: To investigate the cognitive functioning of migraineurs vs nonmigraineurs in a large population-based sample of middle-aged twins where headache diagnoses were established by neurologists. Methods: Twins identified through the population-based Danish Twin Registry participated in face-to-face structured interviews, which included cognitive tests and two previously validated questions screening for migraine. Twins who screened positive for migraine and their co-twins were invited to participate in a telephone-based interview conducted by neurologists, who established headache diagnoses according to the International Headache Society criteria. Cognitive scores on fluency, digit span, delayed word recall, and symbol digit substitution test were compared between migraineurs and nonmigraineurs. Comparisons within monozygotic and dizygotic same sex twin pairs discordant for migraine were also performed. Results: Of the 1,789 twins who were eligible for inclusion in the present study, 1,393 (77.8%) were interviewed. A diagnosis of migraine was established in 536 twins (migraine without aura n = 347; migraine with aura n = 157). Average scores on cognitive tests in twins with migraine or one of the migraine subtypes did not differ from those of nonmigraineurs in any of the tests. Comparisons within twin pairs discordant for migraine produced highly comparable results. Adjustment for possible confounders and stratification by cumulated number of lifetime attacks did not influence the results. Conclusions: A lifetime diagnosis of migraine was not associated with cognitive deficits in middle-aged subjects.

Confined space synthesis is a novel method in zeolite synthesis. It involves crystallization of the zeolite inside the pore system of an inert mesoporous matrix. In this way it is possible to prepare nanosized zeolites with a controlled size distribution by proper choice of the inert matrix. Here, confined space synthesis was adopted to prepare nanosized ZSM-5, zeolite Beta, zeolite X, and zeolite A with tailored crystal size distributions using mesoporous carbon blacks as inert matrices. All zeolites were characterized by X-ray powder diffraction, transmission electron microscopy, and nitrogen adsorption/desorption prior to and after removal of the carbon matrix. ZSM-5 with Si/Al ratios of 50, 100, and infinity (silicalite-1) were synthesized with controlled average crystal sizes in the range 20-75 nm. Nanosized zeolite Beta (7-30 nm), zeolite X (22-60 nm), and zeolite A (25-37 nm) were prepared similarly. Removal of the carbon matrix by controlled combustion allows a convenient method for isolation of the pure and highly crystalline zeolites. Therefore, confined space synthesis appears to be an attractive method for preparation of zeolites with a controlled size distribution.

A case report of congenital intracranial meningioma is presented. We describe what appears to be the first fetal meningioma of the fibroblastic subtype. The literature is reviewed, and the subtype and sex distribution of fetal meningiomas is discussed.