Shocks near Jamming

Non-linear sound is an extreme phenomenon typically observed in solids after violent explosions. But granular media are different. Right when they jam, these fragile and disordered solids exhibit a vanishing rigidity and sound speed, so that even tiny mechanical perturbations form supersonic shocks. Here, we perform simulations in which two-dimensional jammed granular packings are dynamically compressed, and demonstrate that the elementary excitations are strongly non-linear shocks, rather than ordinary phonons. We capture the full dependence of the shock speed on pressure and impact intensity by a surprisingly simple analytical model.Comment: Revised version. Accepted for publication in Phys. Rev. Let

ЭКСПРЕССНАЯ ОЦЕНКА И ОПТИМИЗАЦИЯ ПРЕДЕЛА ОБНАРУЖЕНИЯ В ЭЛЕКТРОТЕРМИЧЕСКОЙ АТОМНО-АБСОРБЦИОННОЙ СПЕКТРОМЕТРИИ

The functional dependence of the photometric error from the photomultiplier voltage for atomic absorption spectrometer ZEEnit-650 produced by Analytik Jena, has been experimentally studied. This was used to develop, on the base of the algorithm, proposed by these authors previously, a fast semi-empirical method for estimating the detection limits in measuring the integrated absorbance. It was shown that this dependence, determined for one instrument, is acceptable to the whole series of ZEEnit instruments. The proposed approach is also applicable to other types of spectrometers. The functional dependence of the photometric error takes into account the design features of spectrometers. Some other parameters, as the baseline offset compensation time, integration time, light intensity, the background absorbance, and amplitude and integral values of the non-selective absorption, it is easy to evaluate by the use one-three determinations of the analytical signal. This is sufficient for the calculation and optimization of the detection limits of any analytes.    Keywords: atomic absorption spectrometry, electrothermal atomization, detection limit, photometric error.(Russian)DOI: http://dx.doi.org/10.15826/analitika.2014.18.2.001 A.O. Dyakov, B.V. L'vov, E.V. NovikovSt. Petersburg State Polytechnic University, St.Petersburg, Russian FederationЭкспериментально изучена функциональная зависимость фотометрической погрешности атомно-абсорбционного спектрометра ZEEnit-650 фирмы Analytik Jena с графитовым атомизатором от напряжения на фотоумножителе во всем рабочем диапазоне значений. Она использована для проверки корректности быстрого, полуэмпирического способа оценки предела обнаружения интегральной атомной абсорбционности, предложенного авторами ранее. Показано, что такая зависимость, найденная для одного прибора, оказалась приемлемой для всей серии приборов ZEEnit. Предложенный подход применим также к спектрометрам других марок. Предварительно снятая функциональная зависимость фотометрической погрешности учитывает их конструктивные особенности, а остальные параметры, такие как время зануления и интегрирования, амплитудное и интегральное значения неселективной абсорбционности нетрудно определить в ходе одного-трех измерений аналитического сигнала.  Этого достаточно для расчета и оптимизации концентрационного и массового пределов обнаружения химических элементов.Ключевые слова: атомно-абсорбционная спектрометрия с электротермической атомизацией, предел обнаружения, фотометрическая погрешность.DOI: http://dx.doi.org/10.15826/analitika.2014.18.2.001

Mechanism of thermal decomposition of magnesium hydroxide

Abstract The kinetic characteristics (the rates of decomposition J and activation energies E a ) of thermal dehydroxylation of Mg(OH) 2 , reported in a number of available publications, have been analysed with the supposition of dissociative evaporation of Mg(OH) 2 in the form of MgO and H 2 O molecules. Despite the considerable differences in the measurement conditions, the experimental values of J and E a have been found to be in agreement with theoretical calculations. The calculations took into account the self-cooling effect, the depressing effect of external water vapor on the decomposition rate, and partial transfer of the energy released in the condensation of MgO(g) to the reactant. The agreement between the calculated and experimental data con®rms the proposed mechanism of decomposition. # 1998 Elsevier Science B.V

Impact on the budget of ONLS program of vedolizumab introduction for the treatment of inflammatory bowel disease

Aim. Evaluation of the impact on the budget of the program for the provision of necessary medications (ONLS program) for the inclusion of a new drug vedolizumab for the treatment of adult patients with moderate or severe active ulcerative colitis (UC) and moderate or severe active Crohn’s disease (CD). Material and methods. The analysis provides a retrospective study based on published data. Based on the results of the auctions for the purchase of compared drugs, the size of the target population of the patients was calculated in the framework of ONLS. The calculation was carried out taking into account the proportion of drugs used for the therapy of inflammatory bowel diseases (IBD) in the total volume of purchased inhibitors of TNF-a. For the target group identified, the budget load is determined with the gradual replacement of TNFa inhibitors with vedolizumab. The horizon of the study was 3 years. The calculations used the average tender prices for the package of the preparation for 2016. Results. It is established that the cost of 1 year of therapy with vedolizumab is lower than that for infliximab, adalimumab or golimumab. The inclusion of vedolizumab in ONLS implies the subsequent replacement of TNFa inhibitors by vedolizumab: in the first year in 11% of patients with UC and 15% of patients with CD, in the second year in 17 and 32%, respectively, in the 3rd year 28 and 43% respectively. This allows to reduce the budget impact for 3 years for the treatment of UC by 11,9 million rubles, and for CD therapy by 24,1 million rubles. With the increase in the share of vedolizumab on the market by replacing TNFa inhibitors, budgetary savings are increasing. Vedolizumab therapy is the most effective option in the treatment of IBD from a clinical and clinico-economic point of view in comparison with TNFa inhibitors. Conclusion. The inclusion of the drug vedolizumab in ONLS is pharmacoeconomically feasible. The use of vedolizumab in terms of Budget impact Analysis is preferable to the current treatment regimen including infliximab, adalimumab, golimumab and cerolizumab pegol