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1.
If cigarette design was exogenous, inefficiencies arising from smoking could be addressed either with a tax per packet or with an ad valorem tax. However, it is well known that the consequences of these two instruments differ when product characteristics are endogenous. We consider three such characteristics: nicotine, tar, and flavor. Implementation of the first‐best social optimum typically requires the capacity to tax or regulate harmful ingredients. Without such a capacity, the next‐best policy often combines a per‐unit tax on cigarettes with an ad valorem subsidy. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
2.
Bielik Peter Bonczek Ondřej Krejčí Přemysl Zeman Tomáš Izakovičová-Hollá Lydie Šoukalová Jana Vaněk Jiří Vojtěšek Bořivoj Lochman Jan Balcar Vladimir J. Šerý Omar 《Clinical oral investigations》2022,26(12):7045-7055
Clinical Oral Investigations - The aim of this study was the analysis of WNT10A variants in seven families of probands with various forms of tooth agenesis and self-reported family history of... 相似文献
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An important part of fundamental research in catalysis is based on theoretical and modeling foundations which are closely connected with studies of single-crystalline catalyst surfaces. These so-called model catalysts are often prepared in the form of epitaxial thin films, and characterized using advanced material characterization techniques. This concept provides the fundamental understanding and the knowledge base needed to tailor the design of new heterogeneous catalysts with improved catalytic properties. The present contribution is devoted to development of a model catalyst system of CeO2 (ceria) on the Cu(111) substrate. We propose ways to experimentally characterize and control important parameters of the model catalyst—the coverage of the ceria layer, the influence of the Cu substrate, and the density of surface defects on ceria, particularly the density of step edges and the density and the ordering of the oxygen vacancies. The large spectrum of controlled parameters makes ceria on Cu(111) an interesting alternative to a more common model system ceria on Ru(0001) that has served numerous catalysis studies, mainly as a support for metal clusters. 相似文献
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Milos Jesenak MD PhD Peter Banovcin MD PhD Zuzana Rennerova MD PhD Lubica Jakusova MD PhD Zuzana Havlicekova MD PhD Vladimir Pohanka MD PhD MPH FCCP Maria Pia Villa MD PhD Roberto Ronchetti MD PhD 《International journal of dermatology》2009,48(9):941-946
Background The atopy patch test (APT) is no longer an experimental method; it is increasingly being used as a standard diagnostic tool for the characterization of patients with aeroallergen- and food-triggered disorders. Some technical aspects of this test still remain to be answered. We aimed to study the reproducibility of this test over time in the general child population.
Methods In a general population of 118 children, we investigated the reproducibility of duplicate APTs with four food allergens in their native form, which were repeated at set intervals from the first test: 7 days (group 1), 14 days (group 2), and 21 days (group 3).
Results We observed very poor reproducibility on both sides of the back in all three studied subgroups. The reproducibility rates and Cohen's κ values did not improve when we did not consider the side of the back. There were no differences in the prevalence of atopy between the subjects with reproducible and nonreproducible APT results. All three groups studied showed no difference in the prevalence rates of atopy. There was no relationship between APT and skin prick test positivity for the same allergen. Questionnaire-derived data about previous food-related reactions did not help in the evaluation of the doubtful nonreproducible APT results with food allergens.
Conclusions Our results show that the reproducibility of food APTs is poor and unsatisfactory over time, and there is an urgent need for the development of optimal, stable, and good-quality APT testing substances. 相似文献
Methods In a general population of 118 children, we investigated the reproducibility of duplicate APTs with four food allergens in their native form, which were repeated at set intervals from the first test: 7 days (group 1), 14 days (group 2), and 21 days (group 3).
Results We observed very poor reproducibility on both sides of the back in all three studied subgroups. The reproducibility rates and Cohen's κ values did not improve when we did not consider the side of the back. There were no differences in the prevalence of atopy between the subjects with reproducible and nonreproducible APT results. All three groups studied showed no difference in the prevalence rates of atopy. There was no relationship between APT and skin prick test positivity for the same allergen. Questionnaire-derived data about previous food-related reactions did not help in the evaluation of the doubtful nonreproducible APT results with food allergens.
Conclusions Our results show that the reproducibility of food APTs is poor and unsatisfactory over time, and there is an urgent need for the development of optimal, stable, and good-quality APT testing substances. 相似文献
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Mathematical modelling of the spatio-temporal response of cytotoxic T-lymphocytes to a solid tumour.
Anastasios Matzavinos Mark A J Chaplain Vladimir A Kuznetsov 《Mathematical medicine and biology》2004,21(1):1-34
In this paper a mathematical model describing the growth of a solid tumour in the presence of an immune system response is presented. In particular, attention is focused upon the attack of tumour cells by so-called tumour-infiltrating cytotoxic lymphocytes (TICLs), in a small, multicellular tumour, without necrosis and at some stage prior to (tumour-induced) angiogenesis. At this stage the immune cells and the tumour cells are considered to be in a state of dynamic equilibrium--cancer dormancy--a phenomenon which has been observed in primary tumours, micrometastases and residual disease after ablation of the primary tumour. Nonetheless, the precise biochemical and cellular mechanisms by which TICLs control cancer dormancy are still poorly understood from a biological and immunological point of view. Therefore we focus on the analysis of the spatio-temporal dynamics of tumour cells, immune cells and chemokines in an immunogenic tumour. The lymphocytes are assumed to migrate into the growing solid tumour and interact with the tumour cells in such a way that lymphocyte-tumour cell complexes are formed. These complexes result in either the death of the tumour cells (the normal situation) or the inactivation (sometimes even the death) of the lymphocytes. The migration of the TICLs is determined by a combination of random motility and chemotaxis in response to the presence of chemokines. The resulting system of four nonlinear partial differential equations (TICLs, tumour cells, complexes and chemokines) is analysed and numerical simulations are presented. We consider two different tumour geometries--multi-layered cell growth and multi-cellular spheroid growth. The numerical simulations demonstrate the existence of cell distributions that are quasi-stationary in time and heterogeneous in space. A linear stability analysis of the underlying (spatially homogeneous) ordinary differential equation (ODE) kinetics coupled with a numerical investigation of the ODE system reveals the existence of a stable limit cycle. This is verified further when a subsequent bifurcation analysis is undertaken using a numerical continuation package. These results then explain the complex heterogeneous spatio-temporal dynamics observed in the partial differential equation (PDE) system. Our approach may lead to a deeper understanding of the phenomenon of cancer dormancy and may be helpful in the future development of more effective anti-cancer vaccines. 相似文献
9.
Vladimir M Krasnopolsky 《Neural networks》2007,20(4):454-461
A new application of the NN ensemble technique to improve the accuracy (reduce uncertainty) of NN emulation Jacobians is presented. It is shown that the introduced ensemble technique can be successfully applied to significantly reduce uncertainties in NN emulation Jacobians and to reach the accuracy of NN Jacobian calculations that is sufficient for the use in data assimilation systems. An NN ensemble approach is also applied to improve the accuracy of NN emulations themselves. Two ensembles linear (or conservative) and nonlinear (uses an additional averaging NN to calculate the ensemble average) were introduced and compared. The ensemble approaches: (a) significantly reduce the systematic and random error in NN emulation Jacobian, (b) significantly reduce the magnitudes of the extreme outliers and, (c) in general, significantly reduce the number of larger errors. It is also shown that the nonlinear ensemble is able to account for nonlinear correlations between ensemble members and to improve significantly the accuracy of the NN emulation as compared to the linear conservative ensemble in terms of systematic (bias), random, and larger errors. 相似文献
10.
Mario von Depka Murtada Hassan Jan Blatn? Petr Smejkal Vladimir Vdovin 《Blood coagulation & fibrinolysis》2006,17(4):311-316
Spontaneous and surgery-associated bleeding in patients with von Willebrand disease (vWD) cannot always be controlled with desmopressin or replacement therapy. This paper presents results on the use of recombinant-activated factor VII (rFVIIa) in patients with vWD included in the internet registry Haemostasis.com. Twenty-eight reports on the use of rFVIIa in vWD were identified from the database and included in this analysis. The bleeding episodes were classified as mild (n = 7), moderate (n = 16), or severe (n = 2), and were unspecified in three cases. The median dose of rFVIIa administered was 94 microg/kg body weight (40-127.3 microg/kg). Bleeding stopped in 23 of 27 evaluable patients (85%) and markedly decreased in three patients; the total response rate was 96% (26/27 patients). Response did not correlate with the type of vWD, the site or severity of the initial bleed, or the rFVIIa dose. Other replacement therapies were infrequently used, and their use was similar in the 24 h before and after rFVIIa administration. Eighteen patients also received antifibrinolytic treatment, but its impact on response was not recorded. Only one adverse event (mild fever) was observed. These cases suggest a role for rFVIIa as a safe and effective therapy for vWD. 相似文献