BioSAXS on the SWING beamline at Synchrotron SOLEIL

Small-angle X-ray scattering (SAXS) of proteins in solution has become a key tool for biochemists and structural biologists, thanks especially to the availability of beamlines with high-throughput capabilities at synchrotron sources. Despite the large spectrum of scientific disciplines tackled on the SWING beamline since its opening in 2008, there has always been a strong commitment to offering state-of-the-art biological SAXS (BioSAXS) instrumentation and data reduction methods to the scientific community. The extremely reliable in-vacuum EigerX-4M detector allows collection of an unlimited number of frames without noise. A small beamstop including a diamond diode-based monitor enables measurements of the transmitted intensity with 0.1% precision as well as a q max/q min ratio as large as 140 at a single distance. The parasitic scattering has been strongly reduced by the installation of new hybrid blades. A new thermally controlled in-vacuum capillary holder including fibre-optics-based spectroscopic functionalities allows the simultaneous use of three spectroscopic techniques in addition to SAXS measurements. The addition of a second high-performance liquid chromatography (HPLC) circuit has virtually eliminated the waiting time associated with column equilibration. The easy in-line connection of a multi-angle light scattering spectrometer and a refractometer allows for an independent determination of the molecular mass and of the concentration of low-UV-absorption samples such as detergents and sugars, respectively. These instrumental improvements are combined with important software developments. The HPLC injection Agilent software is controlled by the SAXS beamline acquisition software, allowing a virtually unlimited series of automated SAXS measurements to be synchronized with the sample injections. All data-containing files and reports are automatically stored in the same folders, with names related to both the user and sample. In addition, all raw SAXS images are processed automatically on the fly, and the analysed data are stored in the ISPyB database and made accessible via a web page.

Hidden Service Circuit Reconstruction Attacks Based on Middle Node Traffic Analysis

Traffic analysis is widely considered as an attack posing a threat to anonymity of the communication and may reveal the real identity of the users. In this paper, a novel anonymous circuit reconstruction attack method that correlates the circuit traffic is proposed. This method then reconstructs a complete communication tunnel using the location of middle nodes found between the hidden and client services. The attack process includes independent determination of the location of the malicious nodes. A traffic correlation framework of AutoEncoder + CNN + BiLSTM is established, based on the Generative Adversarial Networks (GAN) model. BiLSTM applies the packet size and packet interval features of bidirectional traffic and combines the reconstruction loss function with the discrimination loss function to achieve correlated traffic evaluation. After balancing the reconstruction loss and discrimination loss scores, the simulation results confirm that the identification performance of the proposed system is higher than the advanced models.

pinta: The uGMRT data processing pipeline for the Indian Pulsar Timing Array

We introduce pinta, a pipeline for reducing the upgraded Giant Metre-wave Radio Telescope (uGMRT) raw pulsar timing data, developed for the Indian Pulsar Timing Array experiment. We provide a detailed description of the workflow and usage of pinta, as well as its computational performance and RFI mitigation characteristics. We also discuss a novel and independent determination of the relative time offsets between the different back-end modes of uGMRT and the interpretation of the uGMRT observation frequency settings and their agreement with results obtained from engineering tests. Further, we demonstrate the capability of pinta to generate data products which can produce high-precision TOAs using PSR J1909 $-$ 3744 as an example. These results are crucial for performing precision pulsar timing with the uGMRT.

Radio pulsations from the γ-ray millisecond pulsar PSR J2039−5617

The predicted nature of the candidate redback pulsar 3FGL J2039.6−5618 was recently confirmed by the discovery of γ-ray millisecond pulsations (Clark et al. 2020, hereafter Paper I), which identify this γ-ray source as PSR J2039−5617. We observed this object with the Parkes radio telescope in 2016 and 2019. We detect radio pulsations at 1.4 GHz and 3.1 GHz, at the 2.6ms period discovered in γ-rays, and also at 0.7 GHz in one 2015 archival observation. In all bands, the radio pulse profile is characterised by a single relatively broad peak which leads the main γ-ray peak. At 1.4 GHz we found clear evidence of eclipses of the radio signal for about half of the orbit, a characteristic phenomenon in redback systems, which we associate with the presence of intra-binary gas. From the dispersion measure of 24.57 ± 0.03 pc cm−3 we derive a pulsar distance of 0.9 ± 0.2 kpc or 1.7 ± 0.7 kpc, depending on the assumed Galactic electron density model. The modelling of the radio and γ-ray light curves leads to an independent determination of the orbital inclination, and to a determination of the pulsar mass, qualitatively consistent to the results in Paper I.