8,655 research outputs found

    The rotation of the planet Mercury

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    Rotation of planet Mercury from radar observation explained by solar gravitational torque on tidal deformation and equatorial plane asymmetr

    Regular Moebius transformations of the space of quaternions

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    Let H be the real algebra of quaternions. The notion of regular function of a quaternionic variable recently presented by G. Gentili and D. C. Struppa developed into a quite rich theory. Several properties of regular quaternionic functions are analogous to those of holomorphic functions of one complex variable, although the diversity of the quaternionic setting introduces new phenomena. This paper studies regular quaternionic transformations. We first find a quaternionic analog to the Casorati-Weierstrass theorem and prove that all regular injective functions from H to itself are affine. In particular, the group Aut(H) of biregular functions on H coincides with the group of regular affine transformations. Inspired by the classical quaternionic linear fractional transformations, we define the regular fractional transformations. We then show that each regular injective function from the Alexandroff compactification of H to itself is a regular fractional transformation. Finally, we study regular Moebius transformations, which map the unit ball B onto itself. All regular bijections from B to itself prove to be regular Moebius transformations.Comment: 12 page

    Impact hazard protection efficiency by a small kinetic impactor

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    In this paper the ability of a small kinetic impactor spacecraft to mitigate an Earth-threatening asteroid is assessed by means of a novel measure of efficiency. This measure estimates the probability of a space system to deflect a single randomly-generated Earth-impacting object to a safe distance from the Earth. This represents a measure of efficiency that is not biased by the orbital parameters of a test-case object. A vast number of virtual Earth-impacting scenarios are investigated by homogenously distributing in orbital space a grid of 17,518 Earth impacting trajectories. The relative frequency of each trajectory is estimated by means Opik’s theory and Bottke’s near Earth objects model. A design of the entire mitigation mission is performed and the largest deflected asteroid computed for each impacting trajectory. The minimum detectable asteroid can also be estimated by an asteroid survey model. The results show that current technology would likely suffice against discovered airburst and local damage threats, whereas larger space systems would be necessary to reliably tackle impact hazard from larger threats. For example, it is shown that only 1,000 kg kinetic impactor would suffice to mitigate the impact threat of 27.1% of objects posing similar threat than that posed by Apophis

    Shimura varieties in the Torelli locus via Galois coverings of elliptic curves

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    We study Shimura subvarieties of Ag\mathsf{A}_g obtained from families of Galois coverings f:C→Câ€Čf: C \rightarrow C' where Câ€ČC' is a smooth complex projective curve of genus gâ€Č≄1g' \geq 1 and g=g(C)g= g(C). We give the complete list of all such families that satisfy a simple sufficient condition that ensures that the closure of the image of the family via the Torelli map yields a Shimura subvariety of Ag\mathsf{A}_g for gâ€Č=1,2g' =1,2 and for all g≄2,4g \geq 2,4 and for gâ€Č>2g' > 2 and g≀9g \leq 9. In a previous work of the first and second author together with A. Ghigi [FGP] similar computations were done in the case gâ€Č=0g'=0. Here we find 6 families of Galois coverings, all with gâ€Č=1g' = 1 and g=2,3,4g=2,3,4 and we show that these are the only families with gâ€Č=1g'=1 satisfying this sufficient condition. We show that among these examples two families yield new Shimura subvarieties of Ag\mathsf{A}_g, while the other examples arise from certain Shimura subvarieties of Ag\mathsf{A}_g already obtained as families of Galois coverings of P1\mathbb{P}^1 in [FGP]. Finally we prove that if a family satisfies this sufficient condition with gâ€Č≄1g'\geq 1, then g≀6gâ€Č+1g \leq 6g'+1.Comment: 18 pages, to appear in Geometriae Dedicat

    Anharmonicity and self-similarity of the free energy landscape of protein G

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    The near-native free energy landscape of protein G is investigated through 0.4 microseconds-long atomistic molecular dynamics simulations in explicit solvent. A theoretical and computational framework is used to assess the time-dependence of salient thermodynamical features. While the quasi-harmonic character of the free energy is found to degrade in a few ns, the slow modes display a very mild dependence on the trajectory duration. This property originates from a striking self-similarity of the free energy landscape embodied by the consistency of the principal directions of the local minima, where the system dwells for several ns, and of the virtual jumps connecting them.Comment: revtex, 6 pages, 5 figure

    Cost-consequence analysis for human recombinant growth hormone (r-hGH) treatment administered via different devices in children with growth hormone deficiency in Italy

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    Background: The objective of this analysis was to evaluate the cost-consequence of recombinant human growth hormone (r-hGH) administered via the easypod auto-injector (Merck, Darmstadt, Germany) versus conventional devices in children with growth hormone deficiency in Italy. Methods: A patient-level simulation, decision-analytical model was developed to estimate the average height gains and growth hormone treatment costs for a cohort of boys and girls until their bone maturation age. The calculations were performed using listed growth hormone drug prices (base case) and a scenario analysis was also conducted using published tender prices. Costs were discounted at 3%. Results: Due to improved adherence and earlier identification of poor responders, patients receiving somatropin with easypod gained, on average, 3.2 cm more than patients receiving other r-hGH treatments. Somatropin with easypod had the second highest total cost including wastage (\u20ac96,710), but had the second lowest cost per cm gained (\u20ac7699/cm). In the scenario analysis, somatropin with easypod had the lowest cost per cm gained (\u20ac4708/cm) amongst all of the compared treatments. Conclusion: Somatropin with easypod can be cost-saving versus all other r-hGH treatments except Omnitrope when listed drug prices are considered and can be cost-saving versus all other r-hGH treatments when tender drug prices are considered. The easypod device also facilitates cost savings in terms of reduced wastage

    Effect of platelet lysate on uterine response of mares susceptible to persistent mating-induced endometritis

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    Many mares are susceptible to persistent mating-induced endometritis (PMIE), an important cause of reduced fertility. Platelet lysate (PL) derives from freeze-thawing platelets after concentration, so that growth factors are released from the platelets. Among the advantages of PL compared to platelet-rich plasma (PRP), it can be frozen stored and allogenic use for PL might also be conceivable. Platelet-rich plasma beneficially reduced inflammatory response in PMIE mares when administered 24 h pre- or 4 h post-AI. The aim of this study was to test the effect of PL on inflammatory uterine response in mares susceptible to PMIE. A total of 14 mares susceptible to PMIE (based on presence of fluid or inflammatory cells 24 h after AI) underwent an untreated (Ctr) cycle followed by a treated (PL) cycle. From each mare, 100 mL of citrated whole blood was obtained for PRP production by centrifugation. The resultant PRP was brought to a final volume of 10 mL with platelet poor plasma and frozen at −80 °C to obtain PL. On untreated cycles, mares were inseminated with frozen-thawed semen 36 h after ovulation induction. On treated cycles, PL was thawed, infused into the uterus 12 h after ovulation induction, and AIs were performed 24 h later. The number of neutrophils in uterine cytology (score 1(normal)-3(severe inflammation)) evaluated by optical microscopy, uterine fluid accumulation (height x width) and uterine edema (score 0–3) observed in ultrasonography, were analysed. Pregnancy was evaluated by ultrasonography 14 days after ovulation. A significant decrease (P < 0.05) was observed on cytology score (PL 1.3 ± 0.1 vs Ctr 2.0 ± 0.1), fluid accumulation (PL 79.5 ± 30.1 mm2 vs Ctr 342.7 ± 52.9 mm2) and edema score (PL 1.8 ± 0.2 vs Ctr 2.3 ± 0.2) in treated mares. Pregnancy rate in PL-treated cycles (3/12) and control cycles (2/14), were not significantly different (P > 0.05). According to the results, we conclude that treatment with PL in mares classified as susceptible to PMIE appears to reduce the inflammatory response after breeding, based on clinical signs of uterine edema, IUF accumulation and PMNs migration

    Feeding dendritic cells with tumor antigens: self-service buffet or Ă  la carte?

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    Adoptive transfer of autologous dendritic cells (DC) presenting tumor-associated antigens initiate and sustain an immune response which eradicate murine malignancies. Based on these observations, several clinical trials are in progress testing safety and efficacy with encouraging preliminary reports. In these approaches, ex vivo incubation of DC with a source of tumor antigens is required to load the relevant antigenic epitopes on the adequate antigen presenting molecules. Recent data show that in some instances exogenous DC artificially injected into malignant tissue or endogenous DC attracted to the tumor nodule by means of gene transfer of GM-CSF and CD40L into malignant cells result in efficacious antitumor immunity. In the case of intratumoral injection of DC the procedure is curative only if DC had been genetically engineered to produce IL-12, IL-6 or to express CD40L. Evidence has been obtained showing that intratumoral DC can capture and process tumor antigens to be presented to T-lymphocytes. Although the exact mechanisms of tumor antigen acquisition by DC are still unclear, available data suggest a role for heat shock proteins released from dying malignant cells and for the internalization of tumor-derived apoptotic bodies. Roles for tumor necrosis versus apoptosis are discussed in light of the 'danger theory'

    Aerosolization performance of jet nebulizers and biopharmaceutical aspects

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    In this work, 13 jet nebulizers, some of which in different configurations, were investigated in order to identify the biopharmaceutical constraints related to the quality attributes of the medicinal products, which affect their safety, efficiency, compliance, and effectiveness. The aerosolization parameters, including the aerosol output, aerosol output rate, mass median aerodynamic diameter, and fine particle fraction, were determined according to the European Standard EN 13544-1, using sodium fluoride as a reference formulation. A comparison between the aerosol output nebulization time and the fine particle fraction displayed a correlation between the aerosol quality and the nebulization rate. Indeed, the quality of the nebulization significantly increased when the rate of aerosol emission was reduced. Moreover, the performance of the nebulizers was analyzed in terms of respirable delivered dose and respirable dose delivery rate, which characterize nebulization as the rate and amount of respirable product that could be deposited into the lungs. Depending on which of these two latter parameters was used, the nebulizers showed different performances. The differences, in terms of the rate and amount of delivered aerosol, could provide relevant information for the appropriate choice of nebulizer as a function of drug product, therapy, and patient characteristics

    Design of Allosteric Stimulators of the Hsp90 ATPase as New Anticancer Leads

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    Allosteric compounds that stimulate Hsp90 adenosine triphosphatase (ATPase) activity were rationally designed, showing anticancer potencies in the low micromolar to nanomolar range. In parallel, the mode of action of these compounds was clarified and a quantitative model that links the dynamic ligand-protein cross-talk to observed cellular and in vitro activities was developed. The results support the potential of using dynamics-based approaches to develop original mechanism-based cancer therapeutics
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