292 research outputs found
The dynamical environment of asteroid 21 Lutetia according to different internal models
One of the most accurate models currently used to represent the gravity field
of irregular bodies is the polyhedral approach. In this model, the mass of the
body is assumed to be homogeneous, which may not be true for a real object. The
main goal of the present paper is to study the dynamical effects induced by
three different internal structures (uniform, three- and four-layers) of
asteroid (21) Lutetia, an object that recent results from space probe suggest
being at least partially differentiated. The Mascon gravity approach used in
the present work, consists of dividing each tetrahedron into eight parts to
calculate the gravitational field around the asteroid. The zero-velocity curves
show that the greatest displacement of the equilibrium points occurs in the
position of the E4 point for the four-layers structure and the smallest one
occurs in the position of the E3 point for the three-layers structure.
Moreover, stability against impact shows that the planar limit gets slightly
closer to the body with the four-layered structure.
We then investigated the stability of orbital motion in the equatorial plane
of (21) Lutetia and propose numerical stability criteria to map the region of
stable motions. Layered structures could stabilize orbits that were unstable in
the homogeneous model.Comment: 10 pages, 7 figures, and 4 Tables. Accepted for publication in MNRA
Genotyping of Sex Hormone-Related Pathways in Benign and Malignant Human Prostate Tissues: Data of a Preliminary Study
Prostate cancer (PCa) is a major health issue in Westernized countries, representing a common cause of morbidity
and mortality in the elderly male population. Endogenous sex steroids, along with environmental factors (notably
diet) and host immune and inflammatory responses, are likely to cooperate in the pathogenesis of the disease.
Based on the assumption that a complex endocrine–inflammatory-immune interaction is primarily implicated in
human PCa, we have investigated the interplay between sex steroids and inflammation in development and
growth of human PCa. To this end, we have assessed nine functional single nucleotide polymorphisms (SNP)s of
five genes involved in sex hormone-related pathways in both hyperplastic and malignant human prostate tissues,
as well as in matched controls and in a ‘‘supercontrol’’ group composed of male Sicilian centenarians. In particular,
the following genes were investigated: AR-OMIM313700, SRD5A2-NM-000348, CYP19-NM-031226,
ERS1-NM-001122742, ERS2-NM-001040276. A significant association with prostate cancer was found in seven out
of the nine SNPs considered. Although this is a preliminary study and larger investigations are needed to confirm
the role of these genes in PCa development and/or progression, our data might provide an experimental basis to
develop additional or alternative strategies for prevention and treatment of PCa
A Pilot Study on Prostate Cancer Risk and Pro-Inflammatory Genotypes: Pathophysiology and Therapeutic Implications
Host genetic factors are crucial risk determinants for many human cancers. In this framework, an interesting model is
represented by prostate cancer (PC), which is featured by a complex pathophysiology with a strong genetic component. Multiple genes
seem to influence PC risk and several single nucleotide polymorphisms (SNPs) of candidate genes modifying PC susceptibility have been
identified. It is noteworthy the potential association of common SNPs in pro-inflammatory genes with PC risk, since chronic
inflammation is assumed to play a key role in prostate carcinogenesis. With the aim to identify candidate genes as an experimental basis
to develop new strategies for both prevention and treatment of PC, we have investigated the potential role of common SNPs of a gene
cluster (TLR4, TLR2, PTGS2 and 5-Lo), involved in innate and inflammatory response, in PC cases, age-matched controls and
centenarians from Sicily. Six SNPs were genotyped and their association with PC risk determined. Statistical analysis evidenced a
significant association of some pro-inflammatory gene SNPs with an increased risk of PC. Furthermore, significant differences were
observed comparing the three groups in the combined presence of a \u201chigh responder\u201d pro-inflammatory profile. Overall, the present
results suggest the likely association of these SNPs and PC risk, clearly motivating the need of larger studies to confirm the role of these
genes in PC development and/or progression
Amino acids contribute to adaptive thermogenesis. New insights into the mechanisms of action of recent drugs for metabolic disorders are emerging
Adaptive thermogenesis is the heat production by muscle contractions (shivering thermogenesis) or brown adipose tissue (BAT) and beige fat (non-shivering thermogenesis) in response to external stimuli, including cold exposure. BAT and beige fat communicate with peripheral organs and the brain through a variegate secretory and absorption processes − controlling adipokines, microRNAs, extracellular vesicles, and metabolites − and have received much attention as potential therapeutic targets for managing obesity-related disorders. The sympathetic nervous system and norepinephrine-releasing adipose tissue macrophages (ATM) activate uncoupling protein 1 (UCP1), expressed explicitly in brown and beige adipocytes, dissolving the electrochemical gradient and uncoupling tricarboxylic acid cycle and the electron transport chain from ATP production. Mounting evidence has attracted attention to the multiple effects of dietary and endogenously synthesised amino acids in BAT thermogenesis and metabolic phenotype in animals and humans. However, the mechanisms implicated in these processes have yet to be conclusively characterized. In the present review article, we aim to define the principal investigation areas in this context, including intestinal microbiota constitution, adipose autophagy modulation, and secretome and metabolic fluxes control, which lead to increased brown/beige thermogenesis. Finally, also based on our recent epicardial adipose tissue results, we summarise the evidence supporting the notion that the new dual and triple agonists of glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), and glucagon (GCG) receptor − with never before seen weight loss and insulin-sensitizing efficacy − promote thermogenic-like amino acid profiles in BAT with robust heat production and likely trigger sympathetic activation and adaptive thermogenesis by controlling amino acid metabolism and ATM expansion in BAT and beige fat
Machine learning to predict the solar flux and geomagnetic indices to model density and Drag in Satellites
In recent years (2000-2021), human-space activities have been increasing
faster than ever. More than 36000 Earth' orbiting objects, all larger than 10
cm, in orbit around the Earth, are currently tracked by the European Space
Agency (ESA). Around 70\% of all cataloged objects are in Low-Earth Orbit
(LEO). Aerodynamic drag provides one of the main sources of perturbations in
this population, gradually decreasing the semi-major axis and period of the LEO
satellites. Usually, an empirical atmosphere model as a function of solar radio
flux and geomagnetic data is used to calculate the orbital decay and lifetimes
of LEO satellites. In this respect, a good forecast for the space weather data
could be a key tool to improve the model of drag. In this work, we propose
using Time Series Forecasting Model to predict the future behavior of the solar
flux and to calculate the atmospheric density, to improve the analytical models
and reduce the drag uncertainty
- …