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ObjectiveTo compare the disease course in patients with mild Guillain-Barré syndrome (GBS) who were treated with intravenous immunoglobulin (IVIg) or supportive care only.MethodsWe selected patients from the prospective observational International GBS Outcome Study (IGOS) who were able to walk independently at study entry (mild GBS), treated with one IVIg course or supportive care. The primary endpoint was the GBS disability score four weeks after study entry, assessed by multivariable ordinal regression analysis.ResultsOf 188 eligible patients, 148 (79%) were treated with IVIg and 40 (21%) with supportive care. The IVIg group was more disabled at baseline. IVIg treatment was not associated with lower GBS disability scores at 4 weeks (adjusted OR (aOR) 1.62, 95% CI 0.63 to 4.13). Nearly all secondary endpoints showed no benefit from IVIg, although the time to regain full muscle strength was shorter (28 vs 56 days, p=0.03) and reported pain at 26 weeks was lower (n=26/121, 22% vs n=12/30, 40%, p=0.04) in the IVIg treated patients. In the subanalysis with persistent mild GBS in the first 2 weeks, the aOR for a lower GBS disability score at 4 weeks was 2.32 (95% CI 0.76 to 7.13). At 1 year, 40% of all patients had residual symptoms.ConclusionIn patients with mild GBS, one course of IVIg did not improve the overall disease course. The certainty of this conclusion is limited by confounding factors, selection bias and wide confidence limits. Residual symptoms were often present after one year, indicating the need for better treatments in mild GBS.

Superconducting Tunnel Junctions (STJs) have been extensively investigated as photon detectors covering the range from near-infrared to X-ray energies. A 6×6 array of Ta junctions has already been used in an optical spectro-photometer. With this camera, the European Space Agency has performed multiple astronomical observations of optical sources using the William Herschel 4.2 m telescope at La Palma. Following the success of this programe, we are now completing the development of a second generation camera. The goals of this programe were to increase the field of view of the instrument from 4”×4” to 11”×9”, to optimize IR rejection filters (possibly extending the ‘red’ response to ∼1 μm), and to increase the electronics readout speed. For these purposes, we have developed a new STJ array consisting of 10×12 Ta/Al devices as well as an improved readout system. In this paper, we review the instrument's architecture and describe the performance of the new detector array.

Superconducting tunnel junctions (STJs), applied as photon counting detectors, combine intrinsic energy resolution with good detection efficiency and high count rate capability in a wide energy range, from the near infrared to the X-ray. The Science Payload and Advanced Concepts Office of the European Space Agency (ESA), is developing S-Cam : a cryogenic camera for ground-based optical astronomy exploiting an array of Ta STJs. The first generations of this instrument ( S-Cam1–2) , using a 6×6 pixel array, have undergone four campaigns at the 4.2 m William Herschel Telescope at La Palma (Spain). The goals for S-Cam3 , presently under development, are to increase the field of view of the instrument from 4×4″ to 11×9″, to optimize IR rejection, to extend the ‘red’ response and to increase the electronics readout speed. The camera will use a 10×12 array of Ta/Al STJs. Results are presented on the performance of these larger arrays.

Multiple tunneling of quasiparticle charge carriers in a superconducting tunnel junction (STJ) enhances the signal generated by a photon absorption event. It is also an additional source of noise, responsible for a substantial degradation of the energy resolution. Although tunneling is a binomial chance process, governed by a constant tunneling probability, the resulting cumulative statistics of tunnelled quasiparticles depend on time. In particular, the variance of the total number of tunneled quasiparticles reaches a minimum after a finite integration time, corresponding to a minimum in the spectral linewidth. Since the intrinsic energy resolution of the present generation of STJs is mainly limited by the scatter on the number of tunneled quasiparticles, the improvement of the tunnel noise can be experimentally tested by variation of the pulse integration time. An analytical theory is developed that describes the relation between the tunnel noise and the transfer function of the pulse integration hardwa...

Superconducting Tunnel Junctions (STJs) have been extensively investigated as photon detectors covering the range from near-infrared to X-ray energies. A 6x6 array of Tantalum junctions has already been used in an optical spectro-photometer. With this camera, the European Space Agency has performed multiple astronomical observations of optical sources using the William Herschel 4.2m telescope at La Palma. Following the success of this programme, we are now developing a second generation camera. The goals of this programme are to increase the field of view of the instrument from 4x4 to 10.5x9, to optimize IR rejection filters, possibly extending the 'red' response to ∼lum and to increase the electronics readout speed. For these purposes, we are developing a new Superconducting Tunnel Junction Array consisting of 10x12 Tantalum/Aluminium devices as well as an improved readout system. In this paper, we review the instrument's architecture and describe the performance of the new detector.

Superconducting Tunnel Junctions (STJ) have now been under development for a number of years for a wide range of astronomical applications. Devices based on niobium–aluminium or tantalum–aluminium have been shown to be efficient photon counting energy dispersive spectrometers from the near-infra-red to X-ray region of the spectrum. The basic performance characteristics of tantalum-based devices, in terms of detection efficiency, spectral resolution and signal linearity with photon energy, are provided for each wave band of astronomical interest, namely: the near-infra-red (NIR [1–5 μm]), optical [400–1000 nm], ultraviolet (UV [100–400 nm]), extreme ultraviolet (EUV [10–100 nm]), soft X-ray (SXR [100–2000 eV]) and medium X-ray (MXR [2–10 keV]) regions of the spectrum. Although design issues which allow the optimization of the performance for a specific waveband are of importance, we show that current generations of tantalum-based STJs have already very good performance over the whole spectral range. A particular improvement in the resolving power and a description of the role played by various mechanisms in degrading the energy resolution from the theoretical tunnel limited value is given based on specific measurements at relevant photon wavelengths. Additional astronomical characteristics for future applications, such as the time resolution and imaging capability are also presented, based on experimental data and the performance of the first small format 6×6 pixel STJ array described. Finally an assessment is provided on the possibility for further improvements, particularly in the area of higher spectral resolution, through the use of lower band gap superconductors.

A number of 6/spl times/6 element arrays of Ta-based superconducting tunnel junctions have been manufactured for photon counting applications with moderate energy resolution in ground-based optical astronomy. The individual array elements show low leakage, uniform responsivity across the array, good simultaneous Josephson current suppression and minor crosstalk between adjacent pixels. The same arrays have been characterized in the soft X-ray range (E=270-1500 eV). The base electrode response shows good energy resolving power (E//spl Delta/E/spl ap/140). Unwanted spectral features originating from other parts of the detector can be largely eliminated by rise-time filtering. Modifications in the layering are necessary in order to improve the soft X-ray detection efficiency.

Deze voorschriftenbundel bevat voorschriften voor chemische-, fysische- en mineralogische analyses van bodemmateriaal. Daarnaast enkele voorschriften van grondwateranalyses zowel voor laboratorium- als voor veldmethoden. Deze analyses kunnen worden uitgevoerd door de Sectie Bodemanalyse van het Laboratorium voor Bodem- en grondwateronderzoek, t.b.v. bodemprojecten. In dit rapport worden geen voorschriften vermeld voor de analyse van zware metalen en organische microverontreinigingen in bodemmateriaal omdat dergelijke analyses worden uitgevoerd binnen resp. het laboratorium voor Anorganische Chemie (LAC) en het laboratorium voor Organische Chemie (LOC) van het RIVM. Hoewel een aantal analyse methoden nog niet volledig onderzocht is, hebben we deze toch opgenomen in deze bundel. Deze voorschriften dienen dan als basis om verder te werken aan verbetering van deze methodieken. In de eerste plaats is deze bundel dan ook bedoeld voor intern gebruik.

The performance of photon detectors based on superconducting tunnel junctions are related to their current ‐ voltage (I‐V) curve characteristics and, ultimately, to the quality of the thin tunnel barriers (of order 1 nm) which separate the two superconducting thin films. Both the optimization of the spectroscopic performance of these detectors and the development of a reproducible and high yield fabrication route, require a better understanding of barrier quality and growth techniques. Transmission electron microscopy (TEM) and atomic force microscopy (AFM) provide valuable tools for the investigation of the barrier region and for the control of the quality of the different thin films and related interfaces. In this paper, the results of a TEM and AFM evaluation of Nb‐Al‐AlOx‐Nb tunnel junctions are reported, together with their interpretation on the basis of the I‐V curve performance at low temperature (T≥0.3 K). Thickness disuniformities of the Al plus AlOx overlayer and evidence of barrier defects have...

The aim of this study is to investigate political participation and its influencing factors in young adults (18-28 years) with a special focus on education. Besides other factors like income, sex and age, education has a significant impact on the extent of political participation. Several sociological studies indicate that persons with a high level of education are more engaged in political processes. However, this finding is restricted to the influence of formal educational achievements. By considering the tertiary educational sector, this study aims to find out when this effect starts to work. Moreover, it shall be examined if a correlation between the academic political system and the general political system exists and if this can be used as an explanatory factor for political participation. In addition to education, several other factors are analyzed with regard to their impact on political participation. Due to the focus on the tertiary educational sector the analysis is accomplished by comparing students with employed persons. The study sample consists of 392 collectively. For the investigation of the political participation in employed persons the European Social Survey (ESS) is used. The analysis of the students could not be achieved with ESS. Hence, the appropriate variables were measured by an autonomous assessment for the student group (N=163). The influence of several factors is tested by a linear regression. Students have a higher level of political participation than employed persons. Besides others, the most important influencing factors for political participation are interest in politics, close relationship to a political party, faith, religiousness, and political orientation. Academic political system, formal educational level, income, and sex have no influence on political participation., Das Ziel dieser Studie ist es, die politische Partizipation und deren Einflussfaktoren bei jungen Erwachsenen (18-28 Jahre) mit besonderem Fokus auf die Bildung zu untersuchen. Neben anderen Faktoren wie Einkommen, Geschlecht und Alter beeinflusst die Bildung maßgeblich das Ausmaß der politischen Partizipation. Verschiedene soziologische Untersuchungen weisen darauf hin, dass sich Personen mit hohem Bildungsniveau stärker an politischen Prozessen beteiligen. Diese Erkenntnis ist jedoch beschränkt auf den Einfluss formaler Bildungsabschlüsse. Mit dieser Studie soll anhand des tertiären Ausbildungssektors untersucht werden, ab wann dieser Effekt zu wirken beginnt. Des Weiteren wird untersucht, ob ein Zusammenhang zwischen dem hochschulpolitischen System und dem allgemeinen politischen System besteht und ob dies als erklärender Faktor für die politische Partizipation herangezogen werden kann. Zusätzlich zur Bildung werden weitere Faktoren im Hinblick auf ihren Einfluss auf die politische Partizipation analysiert. Aufgrund der Fokussierung auf den tertiären Ausbildungssektors geschieht die Analyse anhand eines Gruppenvergleichs zwischen Studierenden und Berufstätigen. Die Stichprobe besteht insgesamt aus 392 Personen. Für die Untersuchung der politischen Partizipation bei Berufstätigen wird der European Social Survey (ESS) herangezogen. Eine Analyse der Gruppe der Studierenden konnte mit dem ESS Datensatz nicht erfolgen. Daher wurden die interessierenden Variablen in einer eigenständigen Erhebung an der Gruppe der Studierenden erfasst (N=163). Der Einfluss der verschiedenen Faktoren wird anhand einer linearen Regression überprüft. Studierende haben ein höheres politisches Partizipationsniveau als Berufstätige. Die wichtigsten Einflussfaktoren für die politische Partizipation sind u. a. das Interesse an Politik, das Naheverhältnis zu einer Partei, das Vertrauen, Religiosität und die politische Orientierung. Keinen Einfluss hingegen haben u. a. die hochschulpolitische Ebene, formales Bildungsniveau, Einkommen und Geschlecht.

Recent experimental results show a linear energy response in high quality Nb‐Al‐AlO x ‐Nb superconducting tunnel junction detectors for photon energies between 1.5 and 6.4 keV. The experimental data are based on both direct x‐ray illumination and on the escape and re‐absorption of fluorescent photons created in the junction electrodes and in the silicon substrate. The observed linearity of the energy response raises questions on the validity of some theoretical models which describe the relaxation process occurring in a superconducting thin film after x‐ray photoabsorption. Such models generally predict nonlinear effects due to large quasiparticle number densities and short recombination times.

Current research into x‐ray detection using superconducting tunnel junctions indicates that the poor spectral resolution obtained so far, in comparison with theoretical expectations, is partly due to the excellent acoustic coupling of the junction and substrate. The substrate acts both as a source of noise and as a heat sink for the nonequilibrium junction, thus masking the intrinsic response of the superconducting electrodes to photoexcitation. A new design for a superconducting tunnel junction based on an x‐ray detector is presented. The design effectively decouples the substrate and junction and should therefore eliminate many causes of spectral degradation, bringing resolution closer to that predicted theoretically, and thus allowing experimental investigation of the intrinsic superconducting film response to x‐ray photoexcitation. An outline of the way in which the design can be optimized geometrically to achieve the decoupling is given. Further optimization of the intrinsic film response to x‐ray ph...

Superconducting Tunnel Junctions have been investigated in the past as particle and X-ray detectors. We report here on results obtained illuminating Nb-Al-AlOx-Nb junctions with radiation covering the UV to IR (250 – 1100 nm) at 0.30 K. In the presence of continuous illumination, an increase of the subgap current is observed, while the change is found to be consistent with the amount of energy supplied to the junction. Several measurements have been performed in a pulsed mode, showing the detection of pulses containing about 100 photons each, at λ=850 nm. These results have allowed a determination of the mean energy required to create a single charge carrier in Nb, which agrees well with theoretical predictions. Such results open new possibilities for the fabrication of optical photon counting cameras based on Josephson junctions.

The results on the illumination of Superconducting Tunnel Junctions with highly collimated X-rays are presented. The12µm square junction was of extremely high quality with a very low thermal current at temperatures of about 1K and a highly transmissive barrier. The 6keV X-rays were precisely collimated to a spot of about10µm diameter. The results clearly show that different parts of the junction respond to X-ray's differently, introducing a range of charge components in the spectrum. An energy resolution of ∼100eV was achieved for the collimated illumination of the top Nb film.

The results of an investigation into the x‐ray properties of a superconducting tunnel junction (STJ) are presented. The photoabsorption of an x‐ray photon by one of the thin superconducting films of the junction results in the production of quasiparticles, which may subsequently tunnel through the thin oxide barrier into the second superconducting film. The transfer of charge across the barrier is detected, and gives a measure of both the x‐ray photon energy and the effective energy gap e of the superconducting film in which the photoabsorption occurred. A charge output of 55% of the theoretical maximum has been obtained for a niobium‐based STJ. Such a charge output indicates a mean energy e of ≂4.7 meV is required to create a single charge carrier in the junction such that e/Δ≂3, where 2Δ is the junction energy gap. This is the lowest value of e/Δ obtained to date for x‐ray photoabsorption in STJs. The energy resolution of the device is, however, still poor, with a full width half maximum of ≂200 eV for ...

Preliminary results on the X-ray performance of Nb-based superconducting tunnel junctions (STJs) with a highly transmissive barrier are reported. The results show that the energy resolution of these detectors can be improved by collimating the X-ray photons onto the junction barrier area, thus reducing illumination of the surrounding substrate and leads. A charge output of about 50% of the theoretical maximum has been recorded for these STJs, with full width at half maximum resolution of about 200 eV at 6 keV. Several mechanisms which are believed to degrade the energy resolution are also discussed. X-ray events are also detected by other junctions on the same chip which are not illuminated. This may indicate the presence of a marked phonon transmission along the sapphire substrate which acts as a phonon waveguide analogous to the light transmission mechanism in fiber optics. >

The I-V characteristics of strongly coupled symmetric niobium-based superconducting tunnel junctions are found to display steplike structures at voltages less than the gap voltage 2\ensuremath{\Delta}/e. A thorough investigation into the influences of magnetic-field and temperature variations on the structures has been performed. In addition, measurements have been made that allow the homogeneity of the junction barrier to be determined. The experimental results indicate that the structures arise due to either self-coupling, multiple Andreev-reflection processes or multiple-particle tunneling. The data have been analyzed in terms of each of these theories. The results of this analysis appear to indicate that multiple-particle tunneling is the mechanism most likely to be responsible for the subgap structures. If this is the case, this would indicate that three-particle tunneling has been observed in niobium-based junctions. Specific features in the structures are also observed; the current steps do not appear at exactly the voltages expected, and some steps are sharper than others. A modified version of the theory describing multiple-particle tunneling is also presented. It is found that this model is in good agreement with the experimental data. In addition, it is able to describe all features of the structures and indicates the presence of two different, resolved gaps in the superconducting region next to the junction barrier.

The properties of superconducting tunnel junctions based on niobium are investigated. The limiting resolution of such junctions should be ⋍ 4 eV for 6 keV X-rays. Currently only between 2 to 25% of the theoretical charge is detected. The principal loss mechanisms, which not only reduce charge but seriously degrade resolution, are found to be phonon loss to the substrate, and recombination of the excess quasi-particle population in both films. The phonon loss is probably due to relaxation phonons from quasi-particles relaxing towards the bandgap. The quasi-particle self recombination is a direct result of the very large excursion from equilibrium produced during the X-ray photoabsorption process. Finally 6 keV X-rays have been detected directly in sapphire crystals by using the niobium junction only as a detector of beamed ballistic phonons. The use of a suitable crystal as the X-ray absorber and phonon source opens up interesting possibilities for position sensitive spectrometers based on high quality niobium junctions.

The spectral response of a 100×100 μm2 tantalum based superconducting tunnel junction to 5.9 keV x-ray photons from a 55Fe source has been studied. In full illumination the energy resolution for the Mn Kα line complex is 56 eV, dominated by spatial nonuniformity in the response of the detector. When illuminating selectively a 5–10 μm diam spot in the center of the detector, the energy resolution improves to 22 eV, corresponding to 15.7 eV for the individual Mn Kα1 and Mn Kα2 lines. This exceeds the predicted theoretical energy resolution of 7.3 eV for this type of device by only a factor of ∼2.

S-Cam 3 is the third generation of a cryogenic camera, based on superconducting tunnel junctions (STJs), for ground-based optical astronomy, deployed at the 4.2 m William Herschel Telescope (WHT) at La Palma (Spain). It exploits a 10×12 pixel array of Ta/Al STJs, covering a field of view of ∼9″×11″ on the sky. The wavelength band extends from 330–750 nm, with a wavelength resolving power of ∼10 at 500 nm. The detectors are operated at ∼285 mK, achieved with a double stage 4He–3He sorption cooler. Each pixel has its own electronic readout chain at room temperature, with a JFET-based charge sensitive preamplifier. The instrument has undergone extensive testing and calibration, followed by the first observation campaign at La Palma in July 2004. This campaign has focused on point sources with time variability, exploiting the instrument's unique combination of spectrophotometry with high time resolution.

THE charge-coupled device (CCD) has become the detector of choice in optical astronomy. CCDs provide a very linear response to detected photons, are very efficient at some wavelengths, and can now provide coverage of a relatively wide field of view1–3. But they become quite inefficient with decreasing wavelength, and they lack intrinsic wavelength and time resolution. The only way to select specific wavelengths is to place filters in front of the detector, which makes the total system less efficient. Time resolution can be achieved only with short exposures, which are possible only with very bright sources. Here we report a superconducting device that can overcome these limitations, and which has performance characteristics far superior to existing photon counting systems4–7. Our superconducting tunnel junction can detect individual photons at rates up to 2.5 kHz in the wavelength range 200–500 nm, with an intrinsic spectral resolution of 45 nm and a quantum efficiency estimated to be about 50 per cent. The theoretical resolution of the present device is ∼ 20 nm, but use of superconductors with lower transition temperature could improve that to 8 nm.