6,529 research outputs found
Power calculation for gravitational radiation: oversimplification and the importance of time scale
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
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
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
In this paper we study the regularity of viscosity solutions to the following
Hamilton-Jacobi equations In particular, under the
assumption that the Hamiltonian is uniformly convex, we
prove that and belong to the class .Comment: 15 page
Functional Liftings of Vectorial Variational Problems with Laplacian Regularization
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
Determination of cadmium(II), copper(II), manganese(II) and nickel(II) species in Antarctic seawater with complexing resins
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 Mâ1. 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
Systematic review and meta-analysis on the adjunctive use of host immune modulators in non-surgical periodontal treatment in healthy and systemically compromised patients.
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 withââ„â3Â months follow-up were independently searched by two reviewers. Meta-analysis was performed whenââ„â3 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
Enhancement of the Roman Bridge of Canosa in the Ofanto Valley Rural Landscape
The ancient Roman Bridge, 2,000 years old, is located on the old Via Traiana route, three kilometers far from the town of Canosa (Apulia Region), and for many centuries it was the connection between northern and southern part of the Apulia Region along the Adriatic coast. It has an imposing structure stonework, with a donkey back shape, built with five round arches supported by piers sustained by rostrums. During the Second World War, a concrete access way was realized in order to let the British and American army tank pass through the bridge. The âMunicipal Plan of the Tratturiâ qualifies the area as âsheep trails or pathâ that preserves the original consistency or that can be at the same renovated. Aim of the research is the requalification of the study area through analyses, plan and restructuring the ancient routes. In this study, the current status of the area is analyzed in detail and the inconsistency of the interventions is highlighted. The project proposal provides for new tourism paths equipped with cycle/pedestrian tracks and small resting and refreshment areas, intermodal exchange car parks and management structures, allowing the creation of a green tourist-cultural route
Revealing the reality of undergraduate GP teaching in UK medical curricula: a cross-sectional questionnaire study
BACKGROUND: Time in general practice offers medical students opportunities to learn a breadth of clinical knowledge and skills relevant to their future clinical practice. Undergraduate experiences shape career decisions and current recommendations are that 25% of undergraduate curriculum time should be focused on general practice. However, previous work demonstrated that GP teaching had plateaued or reduced in UK medical schools. Therefore, an up-to-date description of undergraduate GP teaching is timely. AIM: To describe the current picture of UK undergraduate GP teaching, including the amount of time and resources allocated to GP teaching. DESIGN AND SETTING: A cross-sectional questionnaire study across 36 UK medical schools. METHOD: The questionnaire was designed based on a previous survey performed in 2011â2013, with additional questions on human and financial support allocated to GP teaching. The questionnaire was piloted and revised prior to distribution to leads of undergraduate GP teaching in UK medical schools. RESULTS: The questionnaire response rate was 100%. GP teaching constituted an average of 9.2% of medical curricula; this was lower than previous figures, though the actual number of GP sessions has remained static. The majority (n = 23) describe plans to increase GP teaching in their local curricula over the next 5 years. UK-wide average payment was 55.60 GBP/student/session of in-practice teaching, falling well below estimated costs to practices. Allocation of human resources was varied. CONCLUSION: Undergraduate GP teaching provision has plateaued since 2000 and falls short of national recommendations. Chronic underinvestment in GP teaching persists at a time when teaching is expected to increase. Both aspects need to be addressed to facilitate high-quality undergraduate GP teaching and promotion of the expert medical generalist role
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