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With the development of digital technologies in the documentation methods for cultural and architectural heritage, platforms and tools have emerged as solutions to collect, manage and produce data for multidisciplinary monitoring and studying purposes. In the context of an incident such as the fire of the Notre-Dame de Paris in April 2019, the considerable mobilization of the architects, scientists and researchers, has led the "digital data" working group to conceive a digital ecosystem capable to collect and integrate existing data, produce new data, share and archive, and finally structure and semantically enrich. One of the particular aspects of this works involves an approach to build a complete digital report of the Notre-Dame de Paris cathedral. With the help of photogrammetric acquisitions of the cathedral, leading to point clouds generation, projects were created in the aïoli platform. The structuring of the collected data (condition report, architectural descriptions, chemical and physical analysis…) has then led to the construction of semantic annotations, accompanied by description sheets and attachments. The vast multidisciplinary studies conducted on the cathedral as well as the large number of projects and annotations built over the course of 4 years constitute a singular collection of data, that will be the object of cross comparison and data interpretation in the future years.

For the past decades, Cultural Heritage (CH) is commonly documented by digital-based imaging and analytical techniques. This documentation is used as a support by heritage scientists to study and help the preservation of CH objects. Multiple techniques or modalities are usually required and applied to complete the documentation and the possible diagnostic from it. In this paper we explored multimodal imaging strategies to survey, analyse and share semantically enriched digital replicas. Three challenging case-studies from the SUMUM research project aims to illustrate efficient multi-source approaches in multi-scalar, multi-temporal and multi-spectral contexts. From multimodal data acquisitions, a photogrammetric-based registration method (TACO) has been developed in order to exploit a 2D/3D semantic annotation process implemented into a CH oriented collaborative web platform (AIOLI). In the exemples showed, the structure and the content of the annotations work is based from condition reports provided by conservation and restoration experts. To this end, all the documentation gathered on CH objects are either directly merged by image based registration while complementary analysis can be spatially anchored to annotations as linked resources. The dissemination part is explored by built-in AIOLI’s collaborative features or external Potree-based viewer, to enhance the accessibility of the final 3D annotated scenes for further expertises or wide-public events and purposes.

We report the development of a multileaf collimator (MLC) for charged particle beams, based on independently actuated tungsten strips that can selectively scatter unwanted particles. The MLC is used in conjunction with an emittance exchange beamline to rapidly generate highly variable longitudinal bunch profiles. The developed MLC consists of 40 independent leaves that are 2 mm wide and can move up to 10 mm and operates in an ultrahigh vacuum environment, enabled by novel features such as magnetically coupled actuation. An experiment at the Argonne Wakefield Accelerator, which previously used inflexible, laser-cut masks for beam shaping before an emittance exchange beamline, was conducted to test functionality. The experiment demonstrated myriad transverse mask silhouettes, as measured on a scintillator downstream of the MLC, and the corresponding longitudinal profiles after emittance exchange, as measured using a transverse-deflecting cavity. Rapidly changing between mask shapes enables expeditious execution of various experiments without the downtime associated with traditional methods. The many degrees of freedom of the MLC can enable the optimization of experimental figures of merit using feed-forward control and advanced machine learning methods.

The evolution of the digital technologies allowed since the early 1990s, to multiply the photogrammetric acquisitions, the digital and mechanical diagnosis and the 3D diagnosis of the sculptural heritage, generating a better knowledge of these objects. The multiplication of these tools therefore allowed to establish multidisciplinary methodologies, generally leading towards less invasive restorations protocol. Here, the diagnosis of a case study is first accomplished, starting with a photogrammetric acquisition, then tested in the two and three dimension annotation platform named aïoli, in order to determine the current possibilities for an innovative use of these tools, benefiting at the diagnosis of the sculptural heritage. On the order hand, along with the multiplication of the multidisciplinary methodologies, a very contemporary problematic arises: the need to improve the communication and discussion between different professionals. The goal was here to offer innovative methods to give all professionals the same vocabulary, a shared knowledge, therefore allowing a better diagnosis of these pieces of art.

The basic mechanisms that govern the generation of an electromagnetic pulse (EMP) following a nuclear detonation in the atmosphere, including heights of burst (HOB) relevant to surface bursts (0 km), near surface bursts (0-2 km), air bursts (2-20 km) and high-altitude bursts (> 20 km), are reviewed. Previous computational codes developed to treat the source region and predict the EMP are discussed. A new 2-D hydrodynamic code (HYDROFLASH) that solves the fluid equations for electron and ion transport in the atmosphere and the coupled Maxwell equations using algorithms extracted from the Conservation Law (CLAW) package for solving multi-dimensional hyperbolic equations with finite volume techniques has been formulated. Simulations include the ground, atmospheric gradient, and an azimuthal applied magnetic field as a first approximation to the geomagnetic field. HYDROFLASH takes advantage of multiprocessor systems by using domain decomposition together with the Message Passing Interface (MPI) protocol for parallel processing. A detailed description of the model is presented along with computational results for a generic 10 kiloton (kT) burst detonated at 0 and 10 km altitude.

Present-day and next-generation accelerators, particularly for applications in driving wakefield-based schemes, require longitudinal beam shaping and attendant longitudinal characterization for experimental optimization. Here we present a diagnostic method which reconstructs the longitudinal beam profile at the location of the wakefield-generating source. The methods described derive the longitudinal profile of a charged particle beam solely from measurement of the time-resolved centroid energy change due to wakefield effects. As such, they are insensitive to the beam losses in post-interaction transport often found in common diagnostics. The reconstruction technique is based on a deconvolution algorithm that is fully generalizable to any analytically or numerically calculable Green’s function for the wakefield excitation mechanism. This method is shown to yield precise features in the longitudinal current distribution reconstruction. We demonstrate the accuracy and efficacy of this technique using simulations and experimental examples, in both plasmas and dielectric structures, and compare them to experimentally measured longitudinal beam profiles. The limits of resolution and applicability to relevant scenarios are also examined.

Recent studies of the performance of radio-frequency (rf) copper cavities operated at cryogenic temperatures have shown a dramatic increase in the maximum achievable surface electric field. We propose to exploit this development to enable a new generation of photoinjectors operated at cryogenic temperatures that may attain, through enhancement of the launch field at the photocathode, a significant increase in five-dimensional electron beam brightness. We present detailed studies of the beam dynamics associated with such a system, by examining an S-band photoinjector operated at 250 MV/m peak electric field that reaches normalized emittances in the 40 nm-rad range at charges (100–200 pC) suitable for use in a hard x-ray free-electron laser (XFEL) scenario based on the LCLS. In this case, we show by start-to-end simulations that the properties of this source may give rise to high efficiency operation of an XFEL, and permit extension of the photon energy reach by an order of magnitude, to over 80 keV. The brightness needed for such XFELs is achieved through low source emittances in tandem with high current after compression. In the XFEL examples analyzed, the emittances during final compression are preserved using microbunching techniques. Extreme low emittance scenarios obtained at pC charge, appropriate for significantly extending temporal resolution limits of ultrafast electron diffraction and microscopy experiments, are also reviewed. While the increase in brightness in a cryogenic photoinjector is mainly due to the augmentation of the emission current density via field enhancement, further possible increases in performance arising from lowering the intrinsic cathode emittance in cryogenic operation are also analyzed. Issues in experimental implementation, including cavity optimization for lowering cryogenic thermal dissipation, external coupling, and cryocooler system, are discussed. We identify future directions in ultrahigh field cryogenic photoinjectors, including scaling to higher frequency, use of novel rf structures, and enabling of an extremely compact hard x-ray FEL.

Models intended to describe the time evolution of a gene network must somehow include transcription, the DNA-templated synthesis of RNA, and translation, the RNA-templated synthesis of proteins. In eukaryotes, the DNA template for transcription can be very long, often consisting of tens of thousands of nucleotides, and lengthy pauses may punctuate this process. Accordingly, transcription can last for many minutes, in some cases hours. There is a long history of introducing delays in gene expression models to take the transcription and translation times into account. Here we study a family of detailed transcription models that includes initiation, elongation, and termination reactions. We establish a framework for computing the distribution of transcription times, and work out these distributions for some typical cases. For elongation, a fixed delay is a good model provided elongation is fast compared to initiation and termination, and there are no sites where long pauses occur. The initiation and termination phases of the model then generate a nontrivial delay distribution, and elongation shifts this distribution by an amount corresponding to the elongation delay. When initiation and termination are relatively fast, the distribution of elongation times can be approximated by a Gaussian. A convolution of this Gaussian with the initiation and termination time distributions gives another analytic approximation to the transcription time distribution. If there are long pauses during elongation, because of the modularity of the family of models considered, the elongation phase can be partitioned into reactions generating a simple delay (elongation through regions where there are no long pauses), and reactions whose distribution of waiting times must be considered explicitly (initiation, termination, and motion through regions where long pauses are likely). In these cases, the distribution of transcription times again involves a nontrivial part and a shift due to fast elongation processes.

Non-luminous relativistic electron beams above thunderclouds have been detected by the radio signals of low frequency ∼40–400 kHz which they radiate. The electron beams occur ∼2–9 ms after positive cloud-to-ground lightning discharges at heights between ∼22–72 km above thunderclouds. Intense positive lightning discharges can also cause sprites which occur either above or prior to the electron beam. One electron beam was detected without any luminous sprite which suggests that electron beams may also occur independently of sprites. Numerical simulations show that beams of electrons partially discharge the lightning electric field above thunderclouds and thereby gain a mean energy of ∼7 MeV to transport a total charge of ∼−10 mC upwards. The impulsive current ∼3 × 10−3 Am−2 associated with relativistic electron beams above thunderclouds is directed downwards and needs to be considered as a novel element of the global atmospheric electric circuit.