Astrophysics with the Laser Interferometer Space Antenna

Laser Interferometer Space Antenna (LISA) will be a transformative experiment for gravitational wave astronomy as it will offer unique opportunities to address many key astrophysical questions in a completely novel way. The synergy with ground-based and other space-based instruments in the electromagnetic domain, by enabling multi-messenger observations, will add further to the discovery potential of LISA. The next decade is crucial to prepare the astrophysical community for LISA's first observations. This review outlines the extensive landscape of astrophysical theory, numerical simulations, and astronomical observations that are instrumental for modeling and interpreting the upcoming LISA datastream. To this aim, the current knowledge in three main source classes for LISA is reviewed: ultra-compact stellar-mass binaries, massive black hole binaries, and extreme or intermediate mass ratio inspirals. The relevant astrophysical processes and the established modeling techniques are summarized. Likewise, open issues and gaps in our understanding of these sources are highlighted, along with an indication of how LISA could help make progress in the different areas. New research avenues that LISA itself, or its joint exploitation with studies in the electromagnetic domain, will enable, are also illustrated. Improvements in modeling and analysis approaches, such as the combination of numerical simulations and modern data science techniques, are discussed. This review is intended to be a starting point for using LISA as a new discovery tool for understanding our Universe

Heat induced denaturation of fibrous hard alpha-keratins and their reaction with various chemical reagents

This dissertation is concerned with the thermal behaviour of fibrous proteins encapsulated in rigid structures, among the most well-known representatives of this class being the alpha-keratins in human hair. In spite of a lot of work in the field, there is still no mechanism proposed for accounting on how thermal denaturation process occurs in hard alpha-keratins. This work aims at proposing a model for the alpha-keratin fibres and a mechanism for their thermal denaturation process. These are further used for understanding the effect of various cosmetic reagents on the thermal stability of the fibres. The use of differential scanning calorimetry, scanning electron microscopy and light microscopy revealed strong structural modifications induced by high temperature in case of heating keratin material in an opened atmosphere. The DSC in open environment was showed to supply misleading information, due to the interference of pyrolysis with the process of interest. Consequently the present work focuses mainly on using DSC of keratins in water excess. The study of the influence of pH, particularly acid values, on thermal behaviour of hard alpha-keratins, indicates limits of the two-phase model used so far to describe the fibrous proteins. We propose a three-phase model for explaining fibrous hard alpha-keratins high thermal stability and their reaction with various reagents. The approach is based on results from DSC study of keratins under various conditions, and is supported by amino-acid analysis, x-ray diffraction, Raman spectroscopy and tensile strength observations. According to the proposed model, the third phase, the interface between crystalline and matrix phases, made of nonhelical tail domains of keratin, scaffolds the intermediate filaments and controls their interaction with chemical reagents as well as their thermal properties. The differential scanning calorimetry measurements carried out in water excess and with different heating rates were used for the kinetic analysis of the endothermic process assigned to the denaturation of the helical material from human hair. We found that the kinetic mechanism is autocatalytic and that the value of the activation energy is rather close to disulphide bond scission than to protein denaturation. This allowed us proposing a multistep mechanism for the thermal denaturation of hard alpha-keratins in water excess that relies on the 3-phase model which describes their structure. The limiting step of the thermal denaturation process is then the scission of S-S bonds between the main morphological components, namely intermediate filaments (IF) and matrix (IFAP). The theoretical proposed model shows a good agreement with the experimental recorded data. The chemical damage induced by bleaching, permanent waving and oxidative dyeing on the structure of hard alpha-keratin fibres (human hair) as revealed by modifications in their thermal behaviour was investigated by using differential scanning calorimetry. Regression analysis of the data from hair samples treated differently shows a linear correlation between the enthalpy of the denaturation peak recorded by DSC and the cystine content of the fibre. The experimental results are evaluated within the framework of a three-phase model in which the nonhelical (globular) terminal domains of keratin promote filament interactions and control the thermal properties of keratin intermediate filaments. Amino-acid analysis, x-ray diffraction and tensile strength measurements provide evidence that the attack of chemical reagents occur preponderantly in the matrix and at the interface between filament and matrix. A possible intermediate state between native and denaturated crystalline helical material is suggested to account for the increased disorder in the IFs-IFAP package induced by harsh treatments. The DSC data suggests that hair keratin IFs can modulate their organisation and thermal properties through chemical induced interactions

Heat induced denaturation of fibrous hard alpha-keratins and their reaction with various chemical reagents

This dissertation is concerned with the thermal behaviour of fibrous proteins encapsulated in rigid structures, among the most well-known representatives of this class being the alpha-keratins in human hair. In spite of a lot of work in the field, there is still no mechanism proposed for accounting on how thermal denaturation process occurs in hard alpha-keratins. This work aims at proposing a model for the alpha-keratin fibres and a mechanism for their thermal denaturation process. These are further used for understanding the effect of various cosmetic reagents on the thermal stability of the fibres. The use of differential scanning calorimetry, scanning electron microscopy and light microscopy revealed strong structural modifications induced by high temperature in case of heating keratin material in an opened atmosphere. The DSC in open environment was showed to supply misleading information, due to the interference of pyrolysis with the process of interest. Consequently the present work focuses mainly on using DSC of keratins in water excess. The study of the influence of pH, particularly acid values, on thermal behaviour of hard alpha-keratins, indicates limits of the two-phase model used so far to describe the fibrous proteins. We propose a three-phase model for explaining fibrous hard alpha-keratins high thermal stability and their reaction with various reagents. The approach is based on results from DSC study of keratins under various conditions, and is supported by amino-acid analysis, x-ray diffraction, Raman spectroscopy and tensile strength observations. According to the proposed model, the third phase, the interface between crystalline and matrix phases, made of nonhelical tail domains of keratin, scaffolds the intermediate filaments and controls their interaction with chemical reagents as well as their thermal properties. The differential scanning calorimetry measurements carried out in water excess and with different heating rates were used for the kinetic analysis of the endothermic process assigned to the denaturation of the helical material from human hair. We found that the kinetic mechanism is autocatalytic and that the value of the activation energy is rather close to disulphide bond scission than to protein denaturation. This allowed us proposing a multistep mechanism for the thermal denaturation of hard alpha-keratins in water excess that relies on the 3-phase model which describes their structure. The limiting step of the thermal denaturation process is then the scission of S-S bonds between the main morphological components, namely intermediate filaments (IF) and matrix (IFAP). The theoretical proposed model shows a good agreement with the experimental recorded data. The chemical damage induced by bleaching, permanent waving and oxidative dyeing on the structure of hard alpha-keratin fibres (human hair) as revealed by modifications in their thermal behaviour was investigated by using differential scanning calorimetry. Regression analysis of the data from hair samples treated differently shows a linear correlation between the enthalpy of the denaturation peak recorded by DSC and the cystine content of the fibre. The experimental results are evaluated within the framework of a three-phase model in which the nonhelical (globular) terminal domains of keratin promote filament interactions and control the thermal properties of keratin intermediate filaments. Amino-acid analysis, x-ray diffraction and tensile strength measurements provide evidence that the attack of chemical reagents occur preponderantly in the matrix and at the interface between filament and matrix. A possible intermediate state between native and denaturated crystalline helical material is suggested to account for the increased disorder in the IFs-IFAP package induced by harsh treatments. The DSC data suggests that hair keratin IFs can modulate their organisation and thermal properties through chemical induced interactions

Up-conversion emission in transition metal and lanthanide co-doped systems: dimer sensitization revisited

Lanthanide (Ln) co-doped transition metal (TM) upconversion (UC) co-doped systems are being intensively investigated for their exciting applications in photonics, bioimaging, and luminescence thermometry. The presence of TM, such as Mo6 + /W6 +, Mn2 +, or Fe3 + determines significant changes in Ln UC emission, such as intensity enhancement, colour modulation, and even the alteration of the photon order. The current mechanism assumes a ground-state absorption/excited-state absorption (ESA/GSA) in TM-Yb dimer followed by direct energy transfer to Er/Tm excited states. We revisit this mechanism by addressing two issues that remain ignored: a dynamical approach to the investigation of the upconversion mechanism and the intrinsic chemical complexity of co-doped TM, Ln systems. To this aim, we employ a pulsed, excitation variable laser across a complete set of UC measurements, such as the emission and excitation spectra and emission decays and analyze multiple grains with transmission electron microscopy (TEM). In the Mo co-doped garnet, the results sustain the co-existence of Mo-free garnet and Mo oxide impurity. In this Mo oxide, the Er upconversion emission properties are fully explained by a relatively efficient sequential Yb to Er upconversion process, with no contribution from Yb-Mo dimer sensitization.ISSN:2045-232

Artificial Intelligence in Obstetric Anomaly Scan: Heart and Brain

Background: The ultrasound scan represents the first tool that obstetricians use in fetal evaluation, but sometimes, it can be limited by mobility or fetal position, excessive thickness of the maternal abdominal wall, or the presence of post-surgical scars on the maternal abdominal wall. Artificial intelligence (AI) has already been effectively used to measure biometric parameters, automatically recognize standard planes of fetal ultrasound evaluation, and for disease diagnosis, which helps conventional imaging methods. The usage of information, ultrasound scan images, and a machine learning program create an algorithm capable of assisting healthcare providers by reducing the workload, reducing the duration of the examination, and increasing the correct diagnosis capability. The recent remarkable expansion in the use of electronic medical records and diagnostic imaging coincides with the enormous success of machine learning algorithms in image identification tasks. Objectives: We aim to review the most relevant studies based on deep learning in ultrasound anomaly scan evaluation of the most complex fetal systems (heart and brain), which enclose the most frequent anomalies