Recurrence intervals between earthquakes strongly depend on history

We study the statistics of the recurrence times between earthquakes above a certain magnitude M$in California. We find that the distribution of the recurrence times strongly depends on the previous recurrence time$\tau_0$. As a consequence, the conditional mean recurrence time$\hat \tau(\tau_0)$between two events increases monotonically with$\tau_0$. For$\tau_0$well below the average recurrence time$\ov{\tau}, \hat\tau(\tau_0)$is smaller than$\ov{\tau}$, while for$\tau_0>\ov{\tau}$,$\hat\tau(\tau_0)$is greater than$\ov{\tau}$. Also the mean residual time until the next earthquake does not depend only on the elapsed time, but also strongly on$\tau_0$. The larger$\tau_0$ is, the larger is the mean residual time. The above features should be taken into account in any earthquake prognosis.Comment: 5 pages, 3 figures, submitted to Physica

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

ASSESSMENT OF THE PROSPECTS FOR RUSSIA TO ENTER THE PATH OF SUSTAINABLE GROWTH AFTER 2021: ANALYSIS OF POSSIBLE DEVELOPMENT RISKS AND DEVELOPMENT OF PROPOSALS FOR RISK MANAGEMENT

The relevance of the topic is due to the fact that the sharp changes in the sectors of the economy generated by the coronavirus pandemic have changed all existing development forecasts. At the same time, a number of new risks have emerged. In this regard, the development of a forecast for the development of economic sectors, taking into account risks and opportunities, seems to be the most important task for the Russian economy. The purpose of the study is to develop a forecast for key parameters of the socio-economic development of Russia, assess the risks of the forecast and develop tools for responding to risk situations, develop a forecast for the development of the financial sector in the Russian Federation in the medium term The subject of the study is the dynamics of the economic development of the Russian Federation in the medium term. The method or methodology of the study is based on the study of key current and retrospective data on the state of the sectors of the economy of the Russian Federation, highlighting the most important risks and building a medium-term forecast. Main research methods: economic observation, economic modeling, construction of economic hypotheses, historical analysis of economic phenomena, formalization and mathematization method, logical interpretation method, axiomatization method, analogy method As a result of the work carried out, the key components of the public sector, financial and credit markets were analyzed, and an assessment was made of the impact of the worsening external environment. Thus, the paper presents estimates of the prerequisites for the forecast and develops three possible scenarios for the development of sectors of the Russian economy. The scientific novelty of the study lies in the development of unique forecasts for the development of sectors of the Russian economy. The recommendations received as a result of the study indicate the need to develop mechanisms for responding to certain risks, taking into account the possible consequences of such an impact, presented in the forecast