6,582 research outputs found

    Power calculation for gravitational radiation: oversimplification and the importance of time scale

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    A simplified formula for gravitational-radiation power is examined. It is shown to give completely erroneous answers in three situations, making it useless even for rough estimates. It is emphasized that short timescales, as well as fast speeds, make classical approximations to relativistic calculations untenable.Comment: Three pages, no figures, accepted for publication in Astronomische Nachrichte

    STEREOSELECTIVE PERCUTANEOUS ABSORPTION AND TRANSDERMAL DELIVERY OF CHIRAL DRUGS

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    The selection of the enantiomeric or racemate form of a drug is a critical issue in the development of transdermal dosage forms. Indeed, the stratum corneum, the rate-limiting barrier to percutaneous absorption, is mainly composed by keratin and ceramides, which could potentially provide a chiral environment. Therefore, the different binding of enantiomers to keratin or the interactions with ceramides may give rise to differences in the permeation profiles of the enantiomers of chiral molecules. Whereas the implication of different physicochemical properties between enantiomers and racemate in the in vitro skin permeation profiles have been studied, other aspects such as the effect of different counter-ions of ionisable chiral drug and different enantiomer of chiral permeation enhancers on skin permeability have not yet been extensively investigated. This work was therefore focused on these two topics to deep actual understanding and to obtain information useful to rationalize the development of transdermal patches. Among the chiral drugs, propranolol (PR) and ibuprofen (IB) were selected. PR is a good candidate as its biological activity is largely associated to a single enantiomer. In humans, S-PR is about 100 times more potent than the R-enantiomer as \u3b2-blocker and the information reported in literature about the in vitro skin permeability suggest that it can be a suitable candidate to transdermal delivery. In the case of IB, largely used in the treatment of musculoskeletal injuries, only the S-enantiomer (S-IB) is therapeutically active, and extensive unidirectional chiral enantiomeric inversion of R to S occurs in vivo. Studies indicates that there aren\u2019t any evidences for the metabolic inversion after topical administration. Till now, although the biological activity of IB resides with the S-enantiomer, the topical preparations available on the market contain the racemate. This work aimed to determinate the skin permeability profiles of the selected drugs and in some case of the their salts, in order to evaluate the enantio-selectivity in the diffusion process. The salts were obtained salifing the drug, either as racemate and pure enantiomer, with different counter-ions, selected on the bases of their physico-chemical characteristics. The experiments were performed by the modified Franz cell method, using human skin epidermis as a membrane and selecting the donor phase on the bases of the drug solubility. Suitable analytical methods for the quantitative determination of the drugs were developed. As a first step the skin permeability test was conducted by using saturated or diluted solutions. On the bases of the preliminary permeability data, the formulation study of monolayer transdermal patches containing the drug in its most appropriate form , and, if necessary, the suitable promotion enhancer, was carried out

    Fidelity and Concurrence of conjugated states

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    We prove some new properties of fidelity (transition probability) and concurrence, the latter defined by straightforward extension of Wootters notation. Choose a conjugation and consider the dependence of fidelity or of concurrence on conjugated pairs of density operators. These functions turn out to be concave or convex roofs. Optimal decompositions are constructed. Some applications to two- and tripartite systems illustrate the general theorem.Comment: 10 pages, RevTex, Correction: Enlarged, reorganized version. More explanation

    SBV regularity for Hamilton-Jacobi equations in Rn\mathbb R^n

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    In this paper we study the regularity of viscosity solutions to the following Hamilton-Jacobi equations ∂tu+H(Dxu)=0inΩ⊂R×Rn. \partial_t u + H(D_{x} u)=0 \qquad \textrm{in} \Omega\subset \mathbb R\times \mathbb R^{n} . In particular, under the assumption that the Hamiltonian H∈C2(Rn)H\in C^2(\mathbb R^n) is uniformly convex, we prove that DxuD_{x}u and ∂tu\partial_t u belong to the class SBVloc(Ω)SBV_{loc}(\Omega).Comment: 15 page

    Functional Liftings of Vectorial Variational Problems with Laplacian Regularization

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    We propose a functional lifting-based convex relaxation of variational problems with Laplacian-based second-order regularization. The approach rests on ideas from the calibration method as well as from sublabel-accurate continuous multilabeling approaches, and makes these approaches amenable for variational problems with vectorial data and higher-order regularization, as is common in image processing applications. We motivate the approach in the function space setting and prove that, in the special case of absolute Laplacian regularization, it encompasses the discretization-first sublabel-accurate continuous multilabeling approach as a special case. We present a mathematical connection between the lifted and original functional and discuss possible interpretations of minimizers in the lifted function space. Finally, we exemplarily apply the proposed approach to 2D image registration problems.Comment: 12 pages, 3 figures; accepted at the conference "Scale Space and Variational Methods" in Hofgeismar, Germany 201

    Systematic review and meta-analysis on the adjunctive use of host immune modulators in non-surgical periodontal treatment in healthy and systemically compromised patients.

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    Considering the central role of inflammation in the pathogenesis of periodontitis, the combination of NSPT with different agents that can modulate the host immune-inflammatory response has been proposed to enhance the outcomes of NSPT. The aim of this paper is to systematically review the literature on the efficacy of systemic host modulators (HMs) as adjuncts to non-surgical periodontal therapy (NSPT) in improving pocket depth (PD) reduction and clinical attachment level (CAL) gain in healthy and systemically compromised patients. RCTs with ≄ 3 months follow-up were independently searched by two reviewers. Meta-analysis was performed when ≄ 3 studies on the same HM were identified. The quality of the evidence was rated according to the GRADE approach to rate the certainty of evidence. 38 articles were included in the qualitative assessment and 27 of them were included in the meta-analysis. There is low/very low evidence that the adjunctive use of sub-antimicrobial dose of doxycicline, melatonin and the combination of omega-3 and low dose aspirin (in type 2 diabetic patients) to NSPT would improve PD and/or CAL. Conflicting evidence is available on the efficacy of probiotics. Future studies controlling for confounding factors, using composite outcomes to define the endpoint of therapy and considering not only the patient- but also as the site-specific effect of systemic HMs are warranted. The dosage, posology and long-term effect of HMs still need to be clarified, also in association to the presence of systemic conditions potentially affecting the response to HMs administration

    Determination of cadmium(II), copper(II), manganese(II) and nickel(II) species in Antarctic seawater with complexing resins

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    The strong species of cadmium(II), copper(II), manganese(II) and nickel(II) in an Antarctic seawater sample are investigated by a method based on the sorption of metal ions on complexing resins. The resins compete with the ligands present in the sample to combine with the metal ions. Two resins with different adsorbing strengths were used. Very stable metal complexes were investigated with the strong sorbent Chelex 100 and weaker species with the less strong resin, Amberlite CG-50. Strong species were detected for three of the considered metal ions, but not for Mn(II). Cu(II) is completely linked to species with a side reaction coefficient as high as log αM(I)=11.6 at pH=7.3. The ligand concentration was found to be similar to that of the metal ion, and the conditional stability constant was around 1020 M−1. In the considered sample, only a fraction of the metal ions Cd(II) and Ni(II) is bound to the strong ligands, with side reaction coefficients equal to log αM(I)=5.5 and 6.5 at pH=7.3 for Cd(II) and Ni(II), respectively. These findings were confirmed by the test with the weaker sorbent Amberlite G-50. It can be calculated from the sorption equilibria that neither Mn(II) nor Ni(II) is adsorbed on Amberlite CG-50 under the considered conditions and, in fact, only a negligible fraction of Mn(II) and Ni(II) was adsorbed. A noticeable fraction of Cd(II) was adsorbed on Amberlite CG-50, meaning that cadmium(II) is partially linked to weak ligands, possibly chloride, while no copper(II) was adsorbed on this resin, confirming that copper(II) is only combined in strong species. These results are similar, but not identical, to those obtained for other seawater samples examined in previous investigations

    Diagnosing congenital Cytomegalovirus infection: Don't get rid of dried blood spots

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    Background: Congenital Cytomegalovirus (cCMV) is a serious global public health issue that can cause irreversible fetal and neonatal congenital defects in symptomatic or asymptomatic newborns at birth. In absence of universal cCMV screening, the retrospective diagnosis of cCMV infection in children is only possible by examining Dried Blood Spot (DBS) samples routinely collected at birth and stored for different time spans depending on the newborn screening regulations in force in different countries. In this article, we summarize the arguments in favor of long-term DBS sample storage for detecting cCMV infection. Main text: CMV infection is the most common cause of congenital infection resulting in severe defects and anomalies that can be apparent at birth or develop in early childhood. Sensorineural hearing loss is the most frequent consequence of cCMV infection and may have a late onset and progress in the first years of life. The virological diagnosis of cCMV is essential for clinical research and public health practices. In fact, in order to assess the natural history of CMV infection and distinguish between congenital or acquired infection, children should be diagnosed early by analyzing biological samples collected in the first weeks of life (3 weeks by using viral culture and 2 weeks by molecular assays), which, unfortunately, are not always available for asymptomatic or mildly symptomatic children. It now seems possible to overcome this problem since the CMV-DNA present in the blood of congenitally infected newborns can be easily retrieved from the DBS samples on the Guthrie cards routinely collected and stored within 3 days from birth in the neonatal screening program for genetic and congenital diseases. Early collection and long-term storage are inexpensive methods for long-term bio-banking and are the key points of DBS testing for the detection of cCMV. Conclusion: DBS sampling is a reliable and inexpensive method for long-term bio-banking, which enables to diagnose known infectious diseases - including cCMV - as well as diseases not jet recognized, therefore their storage sites and long-term storage conditions and durations should be the subject of political decision-making
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