On the Advantages of Using a Strict Hierarchy to Model Astrodynamical Problems

In this paper an algorithm is developed that combines the capabilities and advantages of several different astrodynamical models of increasing complexity. Splitting these models in a strict hierarchical order yields a clearer grasp on what is available. With the effort of developing a comprehensive model overhead, the equations for the spacecraft motion in simpler models can be readily obtained as particular cases. The proposed algorithm embeds the circular and elliptic restricted three-body problems, the four-body bicircular and concentric models, an averaged n-body model, and, at the top hierarchic ladder, the full ephemeris spice-based restricted n-body problem. The equations of motion are reduced to the assignment of 13 time-varying coefficients, which multiply the states and the gravitational potential to reproduce the proper vector field. This approach is powerful because it allows, for instance, an efficient and quick way to check solutions for different dynamics and parameters. It is shown how a gradual increase of the dynamics complexity greatly improves accuracy, the chances of success and the convergence rate of a continuation algorithm, applied to low-energy transfers

A new journal... on spindle cells

Welcome to Clinical Sarcoma Research a new open access, online medical journal providing a forum for clinical knowledge on rare solid cancers - sarcomas. We believe there is a vacuum, which this effort may hope to fill at least in part. Indeed, we ought to share first-hand medical experience and clinically meaningful translational ideas much more within the sarcoma community worldwide. This journal is intended to be one of the many tools we need for this purpose

The Internationalization Process of Small and Medium Companies: the Itlas&LaborLegno Case Study

Small and medium companies’ presence in the international marketplace is consistently increasing in the last decades, arising the interest of several authors and researchers. The existing internationalization literature can be mainly divided into two main fields, the International Business and International Entrepreneurship one. Nonetheless, neither of them alone is able to fully describe the principal factors determining SMEs internationalization’s strategy and performance in the foreign countries. The analysis of the two domains, the International Business and International Entrepreneurship one, together with a qualitative in depth evaluation of the case study Itlas&LaborLegno, promise to solve the research gap identified by many scholars, constituted by the sharp distinction between the two internationalization fields. Overall, this research aims to gain a better comprehension of SMEs’ internationalization process, their definition of competitive advantage and the adopted marketing strategies and tactics, able to overcome SMEs’ lack of financial and tangible resources

Primary vascular bone tumors in the spine: a challenge for pathologists and spine oncology surgeons

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Incidência de lesões osteomioarticulares em atletas amputados: uma revisão de literatura

INTRODUÇÃO: O esporte adaptado para atletas com deficiência existe a mais de 100 anos, mas foi apenas após o fim da Segunda Guerra Mundial que ele foi amplamente implementado. Os desportistas amputados praticantes do esporte adaptado estão expostos ao risco de sofrer lesões assim como os dos esportes convencionais. OBJETIVO: Descrever as principais lesões osteomioarticulares ocorridas em atletas amputados, praticantes de diferentes modalidades esportivas. MÉTODOS: Revisão de literatura em bases de dados como Biblioteca Virtual em Saúde (BVS) e Google Scholar, com pesquisas científicas realizadas entre 2009 e 2020. RESULTADOS: Foram selecionados nove trabalhos, que apresentam informações sobre as lesões em modalidades paradesportivas diversificadas. CONCLUSÃO: Identificou-se através da pesquisa que, nos membros inferiores, os atletas amputados que praticam o esporte adaptado sofrem principalmente lesões como entorse, fraturas, luxações, distensões e contusões. Nos membros superiores ocorrem principalmente lesões no complexo do ombro

Synovial Sarcoma of the Thyroid Gland

Primary synovial sarcoma of the thyroid is an extremely rare condition which has only been reported twice in the literature. We herein report a case of highly aggressive and rapidly lethal primary synovial sarcoma of the thyroid. A 72-year-old woman presented with extensive local invasion, rapid progression, and early distant metastasis secondary to primary thyroid synovial sarcoma. The tumor exhibited an atypical histologic and immunohistochemical staining pattern. Detection of SYT/SSX fusion transcript confirmed the diagnosis of synovial sarcoma. Due to the aggressive nature of primary synovial sarcoma of the thyroid gland, early diagnosis and comprehensive treatment including wide resection and postoperative chemoradiation is required

The co-existence of transcriptional activator and transcriptional repressor MEF2 complexes influences tumor aggressiveness

The contribution of MEF2 TFs to the tumorigenic process is still mysterious. Here we clarify that MEF2 can support both pro-oncogenic or tumor suppressive activities depending on the interaction with co-activators or co-repressors partners. Through these interactions MEF2 supervise histone modifications associated with gene activation/repression, such as H3K4 methylation and H3K27 acetylation. Critical switches for the generation of a MEF2 repressive environment are class IIa HDACs. In leiomyosarcomas (LMS), this two-faced trait of MEF2 is relevant for tumor aggressiveness. Class IIa HDACs are overexpressed in 22% of LMS, where high levels of MEF2, HDAC4 and HDAC9 inversely correlate with overall survival. The knock out of HDAC9 suppresses the transformed phenotype of LMS cells, by restoring the transcriptional proficiency of some MEF2-target loci. HDAC9 coordinates also the demethylation of H3K4me3 at the promoters of MEF2-target genes. Moreover, we show that class IIa HDACs do not bind all the regulative elements bound by MEF2. Hence, in a cell MEF2-target genes actively transcribed and strongly repressed can coexist. However, these repressed MEF2-targets are poised in terms of chromatin signature. Overall our results candidate class IIa HDACs and HDAC9 in particular, as druggable targets for a therapeutic intervention in LMS

Identification of SRF-E2F1 fusion transcript in EWSR-negative myoepithelioma of the soft tissue

Myoepithelial neoplasms (MN) are rare and not well-circumstanced entities displaying a heterogeneous spectrum of genetic abnormalities, including EWSR1, FUS and PLAG1 rearrangements. However, in the remaining MN no other fusion gene has been described and knowledge concerning secondary acquired molecular alterations is still poor. Therefore, we screened 5 cases of MN of the soft tissue by RNA sequencing with the aim of identifying novel fusion transcripts. A novel SRF-E2F1 fusion was detected in two cases: one was negative for other fusions while the other showed also the presence of FUS-KLF17. The fusion was validated through independent techniques and, in both cases, SRF-E2F1 was detected only in a subclone of the tumoral mass. SRF-E2F1 maintained the coding frame, thus leading to the translation of a chimeric protein containing the DNA-binding domain of SRF and the trans-activation domain of E2F1. Moreover, ectopical expression of SRF-E2F1 demonstrated that the chimeric transcript is functionally active and could affect tumor growth. Occurrence in two cases and biological relevance of the two genes involved suggest that the SRF-E2F1 fusion might become a helpful diagnostic tool. Further biologic studies are needed to better assess its role in MN biology