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Optogenetics has transformed studies of neural circuit function, but remains challenging to apply in large brains, such as those of non-human primates (NHPs). A major challenge is delivering intense, spatiotemporally precise, patterned photostimulation across large volumes in deep tissue. Such stimulation is critical, for example, to modulate selectively deep-layer corticocortical feedback projections. To address this unmet need, we have developed the Utah Optrode Array (UOA), a 10×10 glass needle waveguide array fabricated atop a novel opaque optical interposer then bonded to an electrically addressable μLED array.In vivoexperiments with the UOA demonstrated large-scale, spatiotemporally precise, activation of deep circuits in monkey cortex. Specifically, the UOA permitted both focal (confined to single layers/columns), and widespread (multiple layers/columns) optogenetic activation of deep layer neurons, simply by varying the number of activated μLEDs and/or the irradiance. Thus, the UOA represents a powerful optoelectronic device for targeted manipulation of deep-layer circuits in NHP models.

Several methods for calculating jet–surface interaction noise have been developed recently and validated against laboratory measurements. However, further validation cases are required that include...

J. Gary Eden received the B.S. degree in Electrical Engineering from the University of Maryland (College Park) and the M.S. and Ph.D. degrees (also in Electrical Engineering) from the University of Illinois, Urbana, in 1973 and 1976, respectively, and was appointed a National Research Council Postdoctoral Research Associate at the U.S. Naval Research Laboratory (Washington, DC) in 1975. As a research physicist in the Laser Physics Branch (Optical Sciences Division) of NRL from 1976 to 1979, he made several contributions to the area of visible and ultraviolet lasers and laser spectroscopy, including the co-discovery of the KrCl rare gas-halide excimer laser, and received a Research Publication Award (1979) for his work at NRL in which he co-discovered the proton beam pumped laser (Ar–N2, XeF). Since joining the faculty of the University of Illinois in 1979, he has been engaged in research in atomic, molecular and ultrafast laser spectroscopy and physics, the discovery, development, and applications of visible/ultraviolet/vacuum ultraviolet lasers and lamps, and the science and technology of microcavity plasma devices. He has served as Assistant Dean in the College of Engineering, Associate Dean of the Graduate College, and Associate Vice-Chancellor for Research. Currently, he is the Intel Alumni Endowed Chair Emeritus in the Department of Electrical and Computer Engineering and Director of the Laboratory for Optical Physics and Engineering, as well as Research Professor in the Coordinated Science Laboratory, and the Micro and Nanotechnology Laboratory.

We present inverse-designed arrays of vertically-coupled, high-finesse, wavelength-scale photonic crystal cavities in a commercial foundry. Dynamically controlling each pixel with a high-speed (~100 MHz) µLED display enables efficient spatial light modulation with unprecedented spatiotemporal bandwidth.

Challenging imaging applications requiring ultra-short exposure times or imaging in photon-starved environments can acquire extremely low numbers of photons per pixel, (1 MHz) and low incident photon flux (

Several methods for calculating jet–surface interaction noise have been developed recently and validated against laboratory measurements. However, further validation cases are required that include...

Phototherapy with UVA/B or visible wavelengths is used to treat skin disorders such as psoriasis, eczema and vitiligo. Traditionally, phototherapy is carried out in a clinical environment and utilises large fluorescent lamps. hese are now being replaced with more efficient light-emitting diodes (LEDs), a trend that is set to continue thanks to the progress of UV LED technology. LEDs are also facilitating the emergence of at-home devices to improve patient convenience and decrease de mand on the healthcare system [1] . Current at-home devices consist of inflexible LED arrays, which limits their conformability and produces non-uniform light distribution over the treatment area, in turn limiting their efficacy and wearability [2] . As a solution to this problem, we are engineering a flexible light therapy device that combines LEDs and a sub-mm-thick polydimethylsiloxane (PDMS) light sheet in an edge-lit configuration. PDMS has previously been shown as an effective flexible light guide [3 ]; its high transparency from 290 nm upwards and its biocompatibility make it an ideal substrate for a wearable phototherapy device. We will describe the effect of coupling LEDs to our PDMS sheet and discuss design strategies for efficient and uniform light extraction to the treatment area. The PDMS acts as a waveguide and the light diffused through the top surface of the sheet is measured as irradiance (μW/cm2). By adding scattering particles for light extraction a 10-fold enhancement in irradiance has been demonstrated. Utilising a UV LED (385 nm) at an optical power of 25 mW, this approach produces a uniform emission of 140 μW/cm2 over a treatment area of 225 mm2 ( fig. 1). Simulations have shown that the addition of diffractive patterns to the sheet also produces an increased uniform emission.

“Bent-neck” syndrome, an important postharvest problem of cut roses, is probably caused by water supply limitations and/or the structural weakness of vascular bundles of the peduncle tissue. For this reason, advanced knowledge about the microstructures of rose peduncles and their cultivar specific variations may lead to a better understanding of the underlying mechanisms. Synchrotron X-ray computed tomography (SXCT), especially phase-based CT, is a highly suitable technique to nondestructively investigate plants’ micro anatomy. SXCT with monochromatic X-ray beams of 30, 40 and 50 keV photon energy was used to evaluate the three-dimensional inner structures of the peduncles of 3 rose cultivars that differ greatly in their bent-neck susceptibility. Results indicated that this technique achieves sufficiently high spatial resolution to investigate complex tissues. However, further investigations with chlorophyll fluorescence analysis (CFA) and optical microscope imagery reveal different kinds of heavy damage of the irradiated regions induced by synchrotron X-rays; in a cultivar-specific manner, partial destruction of cell walls occurred a few hours after X-ray irradiation. Furthermore, a delayed inhibition of photosynthesis accompanied by the degradation of chlorophyll was obvious from CFA within hours and days after the end of CT measurements. Although SXCT is certainly well suited for three-dimensional anatomical analysis of rose peduncles, the applied technique is not nondestructive.

The nitrogen vacancy (NV) is a photostable emitter in diamond which is optically accessible at room temperature and a potential candidate for quantum information processing as a spin register. The challenge facing research today is the efficient collection and manipulation of the NV’s emissions, such as by enhancing the zero phonon line transitions for a coherent spin-photon interface.Integrating diamond with other photonic materials would allow for resonant coupling of the defect centre to optical devices on large area photonic integrated circuits (PICs). Emitted photons collected by bus waveguides could then be guided elsewhere on chip for entanglement or measurements.This work focuses on integrating ultra-thin diamond membranes with GaN waveguide and resonator devices. Mode simulations (see Fig. 1(a)) show that light can be coupled significantly into and out of the membranes by this method. Membranes of < 200 nm have been fabricated using Ar-Cl2 etch recipes that cumulatively smooth the diamond over time; an r.m.s roughness value of 0.19 nm has been achieved.1 The smooth surface and ultra-low thickness allow a good conformation and strong bonding of the membrane to other materials. This should allow for the integration of diamond membranes with photonic integrated circuits as shown schematically in Fig. (b).Free standing ultra-thin diamond membranes can also be used in tuneable open access cavities – where a low mode volume and high Q factor are desired; 2 or as templates for fabricating diamond optical devices on non-native substrates.3

A fossil plant of Eocene age from Antarctica was studied using X-ray and neutron tomography to reveal the three-dimensional plant structures encased within carbonate nodules. The fossil was identified as a branch and leaves of an araucarian conifer, which grew on the volcanic highlands of the Antarctic Peninsula region approximately 50 million yr ago. Both X-ray and neutron imaging techniques successfully exposed the full three-dimensional structure of the fossil without destroying the original specimen, revealing that most of the fossil was present as voids in the concretion and little organic matter was present. However, neutron tomography was found to produce images with superior quality and detail.

BACKGROUND AND AIMS Cold neutron radiography was applied to directly observe embolism in conduits of liana stems with the aim to evaluate the suitability of this method for studying embolism formation and repair. Potential advantages of this method are a principally non-invasive imaging approach with low energy dose compared with synchrotron X-ray radiation, a good spatial and temporal resolution, and the possibility to observe the entire volume of stem portions with a length of several centimetres at one time. METHODS Complete and cut stems of Adenia lobata, Aristolochia macrophylla and Parthenocissus tricuspidata were radiographed at the neutron imaging facility CONRAD at the Helmholtz-Zentrum Berlin fur Materialien und Energie, with each measurement cycle lasting several hours. Low attenuation gas spaces were separated from the high attenuation (water-containing) plant tissue using image processing. KEY RESULTS Severe cuts into the stem were necessary to induce embolism. The formation and temporal course of an embolism event could then be successfully observed in individual conduits. It was found that complete emptying of a vessel with a diameter of 100 µm required a time interval of 4 min. Furthermore, dehydration of the whole stem section could be monitored via decreasing attenuation of the neutrons. CONCLUSIONS The results suggest that cold neutron radiography represents a useful tool for studying water relations in plant stems that has the potential to complement other non-invasive methods.

was used to analyze the microstructure of rose peduncles. Samples from three rose cultivars, differing in anatomy, were scanned to study the relation between tissue structure and peduncles mechanical strength. Additionally, chlorophyll fluorescence imaging and conventional light microscopy was applied to quantify possible irradiation-induced damage to plant physiology and tissue structure. The spatial resolution of synchrotron X-ray computer microtomography was sufficiently high to investigate the complex tissues of intact rose peduncles without the necessity of any preparation. However, synchrotron X-radiation induces two different types of damage on irradiated tissues. First, within a few hours after first X-ray exposure, there is a direct physical destruction of cell walls. In addition, a slow and delayed destruction of chlorophyll and, consequently, of photosynthetic activity occurred within hours/ days after the exposure. The results indicate that synchrotron X-ray computer microtomography is well suited for three-dimensional visualization of the microstructure of rose peduncles. However, in its current technique, synchrotron X-ray computer microtomography is not really non-destructive but induce tissue damage. Hence, this technique needs further optimization before it can be applied for time-series investigations of living plant materials. K e y w o r d s: plant microstructure, chlorophyll fluorescence imaging, image analysis, mechanical strength, tissue damage

Comprehensive knowledge of plant microstructures and their variations is essential to understanding the mechanisms underlying postharvest quality changes of horticultural products. In cut roses, bent-neck syndrome is a widespread problem damaging millions of flowers well before the end of inherent vase life. Besides water status, structure and function of peduncles, and as a result, tissue strength, may determine bent-neck susceptibility. In this study, phase-contrast X-ray computed microtomography (sXMT) was applied to investigate non-invasively the inner structure of peduncles of samples of three rose cultivars that have been shown to differ greatly in their bent-neck susceptibility. Due to its high resolution, sXMT can be used to three-dimensionally study tissues, and even individual cells, without physically interfering with the product. In 3D sXMT images of peduncle samples of all cultivars, spherical, crystalline, biomineral, high X-ray attenuation particles were observed. These calcium oxalate (CaOx) druses, as clearly identified due to their shape and sizes by microscopic evaluation of concomitantly prepared fresh-cut slices, were mainly scattered in the cortex tissue but were also present less abundantly between vascular bundles. Because CaOx crystals are assumed to serve as structural support, high crystal densities may increase tissue strength. Although the CaOx crystal distribution pattern, the relative radial druse density and the CaOx crystal size differed greatly between samples of the three rose cultivars, these variations do not match the mechanical tissue strength, and hence the bent-neck susceptibility of cultivars as determined in earlier experiments. To the best of our knowledge, this is the first report on the in situ distribution of calcium oxalate crystals in rose peduncles.

Water management is one of the crucial factors regarding the performance and durability of low temperature PEM fuel cells. Amongst other factors, the water balance in an operating fuel cell can be influenced by the humidification of the reaction gases. For transient response investigations of the fuel cell behavior under fast humidification changes a system is needed which is able to humidify the supplied gases in a highly dynamic and reproducible way. Exact knowledge of the water content of the supplied gases is of utmost importance to study humidification effects. In this contribution, a dynamic fuel cell humidification system is presented. Reliability of the concept is proven by using three different methods: straightforward dew point measurements, electrochemical impedance spectroscopy (EIS) and in situ neutron radiography. The test setup is able to provide dew point temperatures with a tolerance range of 1–3 K leading to a highly reproducible fuel cell performance and water content of the complete cell.

Research on investment1 climates and economic growth in developing countries is shifting from institutional ‘best practices’ towards ways in which developmentally successful regimes make use of economic rents. After discussing rent flows in Zimbabwe's history, the paper concludes that the country exhibits a pattern of centralised, short-term rent utilisation, with disastrous results, showing that the centralisation of rent-management by itself does not indicate a ‘developmental patrimonialism’.

The improved collimation and intensity of thermal and cold neutron beamlines combined with recent advances in neutron imaging devices enable high-resolution neutron radiography and microtomography, which can provide information on the internal structure of objects not achievable with conventional X-ray imaging techniques. Neutron detection efficiency, spatial and temporal resolution (important for the studies of dynamic processes) and low background count rate are among the crucial parameters defining the quality of radiographic images and tomographic reconstructions. The unique capabilities of neutron counting detectors with neutron-sensitive microchannel plates (MCPs) and with Timepix CMOS readouts providing high neutron detection efficiency (∼70% for cold neutrons), spatial resolutions ranging from 15 to 55 μm and a temporal resolution of ∼1 μs—combined with the virtual absence of readout noise—make these devices very attractive for high-resolution microtomography. In this paper we demonstrate the capabilities of an MCP–Timepix detection system applied to microtomographic imaging, performed at the ICON cold neutron facility of the Paul Scherrer Institute. The high resolution and the absence of readout noise enable accurate reconstruction of texture in a relatively opaque wood sample, differentiation of internal tissues of a fly and imaging of individual ∼400 μm grains in an organic powder encapsulated in a ∼700 μm thick metal casing.

The neutron tomography instrument CONRAD has been in operation since 2005 at the Hahn-Meitner research reactor at Helmholtz-Zentrum Berlin (HZB). Over the last 5 years, significant developmental work has been performed to expand the radiographic and tomographic capabilities of the beamline [1] , [2] , [3] . New techniques have been implemented, including imaging with polarized neutrons [4] , [5] , [6] , [7] , [8] , [9] , Bragg-edge mapping [10] , [11] , high-resolution neutron imaging and grating interferometry [12] , [13] , [14] , [15] . These methods have been provided to the user community as tools to help address scientific problems over a broad range of topics such as superconductivity, materials research, life sciences [16] , [17] , cultural heritage and paleontology [18] , [19] . Industrial applications including fuel cell research [20] , [21] , [22] , [23] , [24] , [25] , [26] , [27] have also been improved through these new developments. Descriptions and parameters of the developed options will be presented, along with prominent examples.

The accuracy of quantitative neutron transmission radiography can be substantially decreased if highly scattering materials, such as water or plastics, exist in the sample. There are currently two main solutions to this problem: either performing experiments at a large distance between the detector and the sample or employ some numerical correction techniques. In the former case, the spatial resolution is substantially reduced by the limited beam divergence, while the latter correction requires a priori information about the sample and is limited to distances of above ∼2 cm. We demonstrate the feasibility of another technique, namely the possibility to remove the scattered neutron component from the transmitted neutron beam by a very compact polycapillary collimator. These ∼1 mm thick devices can be placed between the sample and the detector and remove most of the neutrons scattered at angles larger than the acceptance angle of the collimator (typically 1°). No image distortions above ∼10 μm scales are introduced by these collimators. The neutron transmission of highly scattering samples (water and plexiglass) is measured in our experiments with and without scatter rejection. In the latter case, the accuracy of measured transmission coefficient was substantially improved by our collimators.

An optimized detector system that allows high-resolution neutron imaging with desired flexibility is described. The presented system can be adapted and integrated with standard CCD-based neutron detectors. Novel neutron scintillating materials with good photon discrimination and optical lens components are tested and optimized for high-resolution neutron tomographic purposes. The presented detector system provides variable field of view and can be used in combination with different techniques, including dark-field, energy-selective, and neutron spin polarized imaging.

We present the use of helium-3 spin filters for polarized neutron imaging of magnetic phenomena. These polarization devices allow improvements in both spatial (factor of 2–3) and temporal (factor of ∼5) resolution compared with previously used solid-state benders. This set-up has been used to visualize small-scale magnetic features in an Fe 65.7 Co 18 Si 0.8 B 15.5 foil with a thickness of 21–22 μm and a saturation magnetization of 1.7 T, and trapped magnetic flux in a superconducting lead cylinder.

Many materials used for energy conversion have a complex structure and chemical composition, knowledge of which is important for both understanding the function of materials and energy conversion systems and for their further development. Synchrotron radiation and neutrons can make an important contribution to understanding the function of such systems. Taking examples from the fields of fuel cells, gas separation membranes, batteries, solar cells, and catalysts, the use of radiography, tomography, diffraction, scattering, and absorption edge spectroscopy is demonstrated. The strength of such methods is the in situ characterization of processes and compositions, and so the focus is on these aspects.

The local distribution of deposited filling gases (CO 2 ) within a sample consisting of a packed bed of ∼1 μm-sized solid glass spheres exposed to a temperature gradient at cryogenic temperatures was investigated by neutron radiography measurements. This local distribution is useful for the understanding of the degradation of the thermal conductivity in cryogenic thermal insulations and the technique of deposition–evacuation (cryoevacuation). As neutron radiography is expected to be sensitive to the CO 2 -distribution, a special sample cell was designed which allows establishing a typical cryogenic temperature gradient (77–293 K). The two-dimensionally resolved transmission of the neutron flux by the cell reveals that all CO 2 is deposited preferentially at and close to the cold wall. The form of the spatial CO 2 -distribution is not affected by the total amount of CO 2 injected into the sample.

Spatial resolution and detection efficiency of neutron imaging detectors are the crucial parameters defining the ultimate resolution in neutron radiography, micro-tomography and other non-destructive testing techniques. The most widely used neutron imaging systems use a neutron-sensitive scintillation screen lens coupled to a CCD or a CMOS sensor. The highest spatial resolution in those devices is achieved using very thin scintillation screens which reduce image blurring due to light spreading in the scintillator. Thus high spatial resolution and high detection efficiency usually could not be achieved in the same device. Neutron counting detectors using neutron-sensitive microchannel plates (MCPs) overcome that deficiency by providing a long neutron absorption path (∼mm scale) and preserving events within a single sub-10 μm pore. At the same time, each neutron in those detectors can be time-tagged with ∼1 μs accuracy. The latest 10B and gadolinium-doped MCPs developed by Nova Scientific were tested at the cold neutron facility ICON of Paul Scherrer Institute and proved to be capable of imaging cold neutrons with 70% detection efficiency. Neutron radiography and micro-tomography confirmed the high spatial resolution capabilities of the latest generation of high efficiency microchannel plates. The high spatial and temporal resolution of our neutron counting detectors allows for high resolution micro-tomography, novel studies of material composition, texture, phase and strain through Bragg edge imaging as well as dynamic studies of magnetic fields inside of thick samples, exploiting the neutron spin interactions with magnetic fields.

The investigation of soot sediments can be crucial for the development of improved components for combustion engines and for the identification of potential hazards. Here we present a number of exemplary studies of soot sediments in such components, which demonstrate the potential of neutron tomography in this field. Neutrons are well suited for imaging massive metal parts, which they can penetrate easily, allowing for imaging entire components with volumes of tens to hundreds of cubic centimeters non-destructively, whilst still being sensitive to lighter elements, in this case hydrogen-containing soot. Up-to-date techniques such as high-resolution and monochromatic neutron tomography have been applied in order to investigate soot sediments from fine particles in the pores of SiC diesel soot filters to massive structures in vent tubes of an aircraft.

Neutrons have zero net electrical charge and can thus penetrate deeply into matter, but their intrinsic magnetic moment makes them highly sensitive to magnetic fields. These properties have been combined with radiographic (2D) and tomographic (3D) imaging methods to provide a unique technique to probe macroscopic magnetic phenomena both within and around bulk matter. Based on the spin-rotation of a polarized neutron beam as it passes through a magnetic field, this method allows the direct, real-space visualization of magnetic field distributions. It has been used to investigate the Meissner effect in a type I (Pb) and a type II (YBCO) superconductor, flux trapping in a type I (Pb) superconductor, and the electromagnetic field associated with a direct current flowing in a solenoid. The latter results have been compared to predictions calculated using the Biot–Savart law and have been found to agree well.

Neutrons are highly sensitive to magnetic fields because of their intrinsic magnetic moment. At the same time, their zero net electrical charge allows them to penetrate thick layers of matter. In combination with standard radiographic and tomographic imaging techniques, these properties have been exploited to visualize magnetic fields in free space and within the bulk of solid, massive, opaque samples. In this paper, the basic principle of this new technique and its realization at the CONRAD instrument at the Helmholtz Centre Berlin (formerly Hahn-Meitner Institute Berlin) are explained. Two application examples will be given: the visualization of the magnetic field around a permanent magnet and the investigation of the displacement of the current density from the core of a conductor to the surface (the skin effect).

Conventional neutron imaging is based on the mapping of the attenuation function for a sample in a neutron beam. The intensity map obtained can be represented as an image with two main parameters: spatial resolution and contrast. The spatial resolution is influenced by the beam definition (collimation) and the detector system, whereas the contrast is governed by the interaction of the neutrons with matter, i.e. through absorption and scattering in the sample.

Kurzfassung Röntgenstrahlen und Neutronen sind zueinander komplementäre Sonden, die sich in vielen Bereichen der Werkstoffforschung gegenseitig ergänzen. Neutronen zeichnen sich im Besonderen durch eine sehr hohe Sensitivität gegenüber Magnetfeldern aus. Vor kurzem konnte gezeigt werden, dass diese Eigenschaft auch für die Bildgebung genutzt werden kann. In Verbindung mit der teilweise hohen Eindringtiefe von Neutronen ist es dadurch möglich, magnetische Feldverteilungen im Inneren massiver Materialien (wie zum Beispiel in Metallen) zwei- und dreidimensional zu visualisieren und zu quantifizieren. Auch Stromdichteverteilungen in elektrischen Leitern können auf diese Weise indirekt über das Magnetfeld untersucht werden. Dies ermöglicht die Erschließung neuer Anwendungsbereiche in der Werkstoffforschung. Einige Beispiele hierfür werden in diesem Artikel vorgestellt.

Precession of neutron spin in a magnetic field can be used for mapping of a magnetic field distribution, as demonstrated previously for static magnetic fields at neutron beamline facilities. The fringing in the observed neutron images depends on both the magnetic field strength and the neutron energy. In this paper we demonstrate the feasibility of imaging periodic dynamic magnetic fields using a spin polarized cold neutron beam. Our position sensitive neutron counting detector, providing with high precision both the arrival time and position for each detected neutron, enables simultaneous imaging of multiple phases of a periodic dynamic process with microsecond timing resolution. The magnetic fields produced by 5 and 15 loop solenoid coils of 1 cm diameter, are imaged in our experiments with 100 amp; 956;m resolution for both dc and 3 kHz ac currents. Our measurements agree well with theoretical predictions of fringe patterns formed by neutron spin precession. We also discuss the wavelength dependence and magnetic field quantification options using a pulsed neutron beamline. The ability to remotely map dynamic magnetic fields combined with the unique capability of neutrons to penetrate various materials e.g., metals , enables studies of fast periodically changing magnetic processes, such as formation of magnetic domains within metals due to the presence of ac magnetic fields

Neutron imaging is a method for non-destructive investigations of objects in science and engineering. Different contrast mechanisms provide information about the interior structure of samples. High-resolution neutron tomography is used for the reconstruction of the three-dimensional matrix of attenuation coefficients in the sample. Energy-selective radiography performed around Bragg-cut-off wavelengths makes structure defects and textures visible. Imaging with polarized neutrons makes it possible to visualize magnetic fields in bulk samples. Examples of different experimental techniques will be presented and discussed.

~1.7 W output power at 2.3 mum is demonstrated from a semiconductor disk laser pumped by a 905 nm high-power pulsed semiconductor laser. The thermal characteristics and wavelength shift are studied over the 100-200 ns pump pulse.

At first sight, this paper is concerned about the «unique» story of Mgr Jean- Joseph Languet's catechism. Written shortly after the bulle Unigenitus was promulgated against the Jansenism (1713), it was first prescribed in Soissons (1716), then in Sens (1731). In this last diocese, several ecclesiastics refused to use it as the official manual to teach Christian doctrine and appealed to the parliament to condemn the work, accusing its producer of having introduced novelties in the traditional doctrine. But behond the narrative, the reconstruction of these facts shows to what extent the catechism, like other knowledge, was susceptible to inflections relative to its time and place of production, far from the changeless product described by the producers. In the specific context of crisis in the religious and secular authority during the first XVIIIe century France, the Catéchisme de Sens became a strategic target in the jansenist-antijansenist conflict and being so, largely transformed the manual of catechism and its statute, and took a more important part than usually expected in the profound social mutation which will reach its outcome late in the century., Résumé Au premier plan, cet article raconte l'histoire mouvementée du catéchisme de Mgr Jean-Joseph Languet, évêque de Soissons puis archevêque de Sens. Ce manuel, rédigé au lendemain de la promulgation de la bulle Unigenitus contre le jansénisme (1713), fut pris à parti par plusieurs ecclésiastiques sénonais qui refusèrent de l'enseigner, l'attaquèrent devant le parlement de Paris et accusèrent son producteur d'innover en matière doctrinale. La reconstitution de cette polémique, au-delà de la narration des faits, montre jusqu'à quel point ce petit manuel de la doctrine chrétienne est, comme tout savoir, sensible au temps et au lieu de sa production. Loin d'être le produit immuable que décrivent les producteurs, le catéchisme porte en lui les stigmates du contexte socio -culturel d'où il émane. Dans le contexte du conflit d'autorité qui marqua l'histoire du premier XVIIIe siècle français, la cible que devint le Catéchisme de Sens transforma le statut du livre-catéchisme et l'inscrivit au cœur de cette profonde mutation sociale qui devait trouver son aboutissement à la fin du siècle., Dawson Nelson-Martin. Cathéchisme de Sens politique religieuse et enjeux politiques. In: Histoire, économie et société, 1993, 12ᵉ année, n°2. pp. 235-262.

High-resolution neutron dark-field imaging has been applied to study magnetic domains in sheets of commercial grain-oriented electrical steel enveloped in an insulating layer. The resulting images have been compared to those obtained using conventional magnetic powder patterns and a clear correlation has been found, with the neutron technique providing complementary information about the internal structures of the material. An understanding of the magnetic structure of these materials is important for improving the performance characteristics – particularly minimizing core loss – in the electrical devices in which they are used.

An elliptic focusing neutron guide was combined with a cold neutron imaging instrument to produce a cone-beam, whose parameters were then characterized both at the focal point and at the detector position. This point source geometry provides improved experimental conditions for tomographic applications, providing a larger beam cross-section and enabling geometric magnification. The experimental data were compared with Monte Carlo simulations and both experiments and simulations demonstrate superior spectral and geometric homogeneity of the cone-beam setup compared to the conventional pinhole geometry.