Random vibration of linear and nonlinear structural systems with singular matrices: A frequency domain approach

A frequency domain methodology is developed for stochastic response determination of multi-degree-of-freedom (MDOF) linear and nonlinear structural systems with singular matrices. This system modeling can arise when a greater than the minimum number of coordinates/DOFs is utilized, and can be advantageous, for instance, in cases of complex multibody systems where the explicit formulation of the equations of motion can be a nontrivial task. In such cases, the introduction of additional/redundant DOFs can facilitate the formulation of the equations of motion in a less labor intensive manner. Specifically, relying on the generalized matrix inverse theory, a Moore-Penrose (M-P) based frequency response function (FRF) is determined for a linear structural system with singular matrices. Next, relying on the M-P FRF a spectral input-output (excitation-response) relationship is derived in the frequency domain for determining the linear system response power spectrum. Further, the above methodology is extended via statistical linearization to account for nonlinear systems. This leads to an iterative determination of the system response mean vector and covariance matrix. Furthermore, to account for singular matrices, the generalization of a widely utilized formula that facilitates the application of statistical linearization is proved as well. The formula relates to the expectation of the derivatives of the system nonlinear function and is based on a Gaussian response assumption. Several linear and nonlinear MDOF structural systems with singular matrices are considered as numerical examples for demonstrating the validity and applicability of the developed frequency domain methodology

LICIACube Mission: The Fastest Fly-By Ever Done by a CubeSat

As SmallSats are gathering an ever-increasing importance for all types of space missions, they are asked more often to operate in harshest environments and to complete the most complex tasks. One of these demanding technical challenges arises in the frame of the planetary defense. Space missions towards asteroids have garnered the due attention in recent years and, in this regard, NASA has developed the Double Asteroid Redirection Test (DART) mission, in which the Italy will lend its contribution. While DART acts as a kinetic impactor deflecting the orbit of the asteroid Dimorphos, the moon of the targeted binary system Didymos, the Light Italian CubeSat for Imaging of Asteroid (LICIACube) collects and gathers valuable images of the effect of the DART impact on the rocky body. LICIACube will allow to study the structure and evolution of the ejecta plume resulting from the impact, and to model both impacted and non-impacted sides of Dimorphos. LICIACube is an Italian Space Agency (ASI) project, whose design, integration and testing have been assigned to the aerospace company Argotec. The scientific team is enriched by University of Bologna team, supporting the orbit determination and the satellite navigation, Polytechnic of Milan, for mission analysis support and optimization and INAF (National Institute of Astrophysics), which provides support in the scientific operations of the satellite, instrument calibrations and data exploitation. This work focuses on the fly-by of LICIACube which will be accomplished using the imaging capabilities provided by theArgotecHAWK-6 platform and by the autonomous navigation system. In order to acquire high-resolution images, LICIACube approaches Dimorphos at a relative distance of 55km. The very close fly-by, the high relative velocity of ∼7 km/s with respect to the asteroid and the need to keep LICIACube camera pointed at Dimorphos make the mission very challenging. In addition, since the binary asteroid system is ∼10 million kilometers away from Earth, the fly-by has to be performed with no real time commanding. As a result, LICIACube shall be able to autonomously analyze all information from its sensors to track the asteroid. The evaluation and subsequent solutions to this problem are presented in this paper, as well as a unit-level description of the parts included in the autonomous navigation system. Finally, an overview of the verification of both unit-level and system-level strategies is outlined

Update on the pathogenesis and genetics of Paget's disease of bone

Studies over the past two decades have led to major advances in the pathogenesis of Paget's disease of bone (PDB) and particularly on the role of genetic factors. Germline mutations of different genes have been identified, as a possible cause of this disorder, and most of the underlying pathways are implicated in the regulation of osteoclast differentiation and function, whereas other are involved in cell autophagy mechanisms. In particular, about 30 different germline mutations of the Sequestosome 1 gene (SQSTM1) have been described in a significant proportion of familial and sporadic PDB cases. The majority of SQSTM1 mutations affect the ubiquitin-binding domain of the protein and are associated to a more severe clinical expression of the disease. Also, germline mutations in the ZNF687 and PFN1 genes have been associated to severe, early onset, polyostotic PDB with increased susceptibly to neoplastic degeneration, particularly giant cell tumor. Mutations in the VCP (Valosin Containing Protein) gene cause the autosomal dominant syndrome "Inclusion Body Myopathy, PDB, Fronto-temporal Dementia," characterized by pagetic manifestations, associated with myopathy, amyotrophic lateral sclerosis and fronto-temporal dementia. Moreover, germline mutations in the TNFRSF11A gene, which encodes for RANK, were associated with rare syndromes showing some histopathological, radiological, and clinical overlap with PDB and in two cases of early onset PDB-like disease. Likewise, genome wide association studies performed in unrelated PDB cases identified other potential predisposition genes and/or susceptibility loci. Thus, it is likely that polygenic factors are involved in the PDB pathogenesis in many individuals and that modifying genes may contribute in refining the clinical phenotype. Moreover, the contribution of somatic mutations of SQSTM1 gene and/or epigenetic mechanisms in the pathogenesis of skeletal pagetic abnormalities and eventually neoplastic degeneration, cannot be excluded. Indeed, clinical and experimental observations indicate that genetic susceptibility might not be a sufficient condition for the clinical development of PDB without the concomitant intervention of viral infection, in primis paramixoviruses, and/or other environmental factors (e.g., pesticides, heavy metals or tobacco exposure), at least in a subset of cases. This review summarizes the most important advances that have been made in the field of cellular and molecular biology PDB over the past decades. © 2022 Gennari, Rendina, Merlotti, Cavati, Mingiano, Cosso, Materozzi, Pirrotta, Abate, Calabrese and Falchetti

Design and Analysis of the Cis-Lunar Navigation for the ArgoMoon CubeSat Mission

In the framework of the Artemis-1 mission, 10 CubeSats will be released, including the 6U CubeSat ArgoMoon, built by the Italian company Argotec and coordinated by the Italian Space Agency. The primary goal of ArgoMoon is to capture images of the Interim Cryogenic Propulsion Stage. Then, ArgoMoon will be placed into a highly elliptical orbit around the Earth with several encounters with the Moon. In this phase, the navigation process will require a precise Orbit Determination (OD) and a Flight Path Control (FPC) to satisfy the navigation requirements. The OD will estimate the spacecraft trajectory using ground-based radiometric observables. The FPC is based on an optimal control strategy designed to reduce the dispersion with respect to the reference trajectory and minimize the total ΔV. A linear approach was used to determine the optimal targets and the number and location of the orbital maneuvers. A covariance analysis was performed to assess the expected OD performance and its robustness. The analysis results show that the reference translunar trajectory can be successfully flown and the navigation performance is strongly dependent on the uncertainties of the ArgoMoon’s Propulsion Subsystem and of the orbit injection

Comprehensive analysis of the chromatin landscape in Drosophila melanogaster.

Chromatin is composed of DNA and a variety of modified histones and non-histone proteins, which have an impact on cell differentiation, gene regulation and other key cellular processes. Here we present a genome-wide chromatin landscape for Drosophila melanogaster based on eighteen histone modifications, summarized by nine prevalent combinatorial patterns. Integrative analysis with other data (non-histone chromatin proteins, DNase I hypersensitivity, GRO-Seq reads produced by engaged polymerase, short/long RNA products) reveals discrete characteristics of chromosomes, genes, regulatory elements and other functional domains. We find that active genes display distinct chromatin signatures that are correlated with disparate gene lengths, exon patterns, regulatory functions and genomic contexts. We also demonstrate a diversity of signatures among Polycomb targets that include a subset with paused polymerase. This systematic profiling and integrative analysis of chromatin signatures provides insights into how genomic elements are regulated, and will serve as a resource for future experimental investigations of genome structure and function

Imatinib mesylate in the treatment of newly diagnosed or refractory/resistant c-KIT positive acute myeloid leukemia. Results of an Italian Multicentric Phase II Study

We evaluated safety and efficacy of imatinib (600 mg) in 36 c-KIT+ acute myeloid leukemia patients not amenable to receive conventional chemotherapy. No patient achieved complete remission. One patient obtained a hematologic improvement (platelet increase with transfusion independence). Median overall survival was 3 months (0.5-44+). Non-hematologic toxicity was overall mild

Imatinib mesylate in the treatment of newly diagnosed or refractory/resistant c-KIT positive acute myeloid leukemia. Results of an Italian Multicentric Phase II Study

We evaluated safety and efficacy of imatinib (600 mg) in 36 c-KIT+ acute myeloid leukemia patients not amenable to receive conventional chemotherapy. No patient achieved complete remission. One patient obtained a hematologic improvement (platelet increase with transfusion independence). Median overall survival was 3 months (0.5-44+). Non-hematologic toxicity was overall mild