Concentration and Diffusion of Nutrients in the Interpore–Bottom Water System of the Ob River Estuary

Oceanology - On cruise 76 in 2019, the R/V Akademik Mstislav Keldysh completed the Gulf of Ob–Kara Sea slope transect. Samples of bottom water and two sediment layers 1 cm thick were obtained...     

“Pure” supernovae and accelerated expansion of the Universe

A special class of type Ia supernovae that is not subject to ordinary and additional intragalactic gray absorption and chemical evolution has been identified. Analysis of the Hubble diagrams constructed for these supernovae confirms the accelerated expansion of the Universe irrespective of the chemical evolution and possible gray absorption in galaxies.     

The limits of validity of the Frequency Ratio Method: The particular case of γ Doradus stars

This work provides a general vision of the limits of validity of the Frequency Ratio Method applied to the g‐mode pulsators in asymptotic regime, the γ Doradus stars. In particular, the work is mainly focused on the role of rotation which is found one of the most important source of uncertainty of the method. The particular case of the moderately rotating γ Doradus star HD48501 is discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Babbling brook to thunderous torrent: Using sound to monitor river stage

The passive, ambient sound above the water from a river has previously untapped potential for determining flow characteristics such as stage. Measuring sub-aerial sound could provide a new, efficient way to continuously monitor river stage, without the need for in-stream infrastructure. Previous published work has suggested that there might be a relationship between sound and river stage, but the analysis has been restricted to a narrow range of flow conditions and river morphologies. We present a method to determine site suitability and the process of how to record and analyse sound. Data collected along a 500 m length of the River Washburn during July 2019 is used to determine what makes a site suitable for sound monitoring. We found that sound is controlled by roughness elements in the channel, such as a boulder or weir, which influences the sound produced. On the basis of these findings, we collect audio recordings from six sites around the northeast of England, covering a range of flow conditions and different roughness elements, since 2019. We use data from those sites collected during storms Ciara and Dennis to produce a relationship between this sound and river stage. Our analysis has shown a positive relationship between an R² of 0.73 and 0.99 in all rivers, but requires careful site selection and data processing to achieve the best results. We introduce a filter that is capable of isolating a river's sound from other environmental sound. Future work in examining the role of these roughness elements is required to understand the full extent of this technique. By demonstrating that sound can operate as a hydrometric tool, we suggest that sound monitoring could be used to provide cost-effective monitoring devices, either to detect relative change in a river or, after more research, a reliable stage measurement.     

Stochastic variability in the atmospheric activity of Jupiter

The atmospheric activity of Jupiter exhibits quasi-periodic character attributed to the stochastic nature of the involved mechanisms. Periodicities between 4–33 years are obtained employing four spectrum analysis methods, (power spectrum employing the Blackman-Tukey window, maximum entropy, Fourier, autocorrelation), whilst, their significance and their stationarity has been established with the application of general statistical tests (Kolmogorov-Smirnov, one sample and two sample test, randomness test, chi-square, various orders of autoregressive process, analysis of truncated records).Deceased.     

Closed-form solution of P4P or the three-dimensional resection problem in terms of Möbius barycentric coordinates

 The perspective 4 point (P4P) problem - also called the three-dimensional resection problem - is solved by means of a new algorithm: At first the unknown Cartesian coordinates of the perspective center are computed by means of M?bius barycentric coordinates. Secondly these coordinates are represented in terms of observables, namely space angles in the five-dimensional simplex generated by the unknown point and the four known points. Substitution of M?bius barycentric coordinates leads to the unknown Cartesian coordinates (2.8)–(2.10) of Box 2.2. The unknown distances within the five-dimensional simplex are determined by solving the Grunert equations, namely by forward reduction to one algebraic equation (3.8) of order four and backward linear substitution. Tables 1.–4. contain a numerical example. Finally we give a reference to the solution of the 3 point (P3P) problem, the two-dimensional resection problem, namely to the Ansermet barycentric coordinates initiated by C.F. Gau? (1842), A. Schreiber (1908) and A.␣Ansermet (1910). Received: 05 March 1996; Accepted: 15 October 1996     

Solving the problem of shock wave attenuation in an obstacle during a contact explosion of a high-energy material charge

A problem of estimation of shock wave attenuation in an obstacle under an explosion of a high-energy material (explosive) charge on its surface is considered. An algorithm for its solution is proposed using the analytical and semiempirical dependences generally recognized in explosion physics.     

Evolution and Spectrum of the Radio Emission of Tycho’s Supernova Remnant

The radio spectrum of Tycho’s Supernova Remnant is constructed at frequencies 12.6–143 000 MHz for epoch 2010.3, taking into account the secular decrease in the radio flux density of the remnant at the rate d = ?(0.46 ± 0.03)%/year:

$$S_\nu ^{3C10} (t = 2010.3) = (43.1 \pm 1.8 Jy)(\nu [GHz])^{ - (0.592 \pm 0.019) + (0.041 \pm 0.012)\log (\nu [GHz])} .$$

The spectrum has positive curvature. The presence of a low-frequency turnover in the spectrum of the radio source 3C10 with its maximum at 7.7 MHz is predicted, due to absorption in the interstellar medium in the direction toward the source.

     

The first field-based descriptions of pumping-induced saltwater intrusion and upconing

Development of the ideas about the equilibrium between freshwater and saline water has received considerable attention in the literature, but little has been written so far about the earliest scientific works about well salinization. Based on a review of the literature from the second half of the 19th century and the early 20th century, this historical note explores how insights into groundwater abstraction and saltwater intrusion developed, and examples of the earliest field studies are provided. Fundamental research was driven by the need for increasing water supply, but the progress of science did not lead to sustainable management practices everywhere. Research outcomes were shared between scientists of different countries, marking the beginning of coastal hydrogeology as a scientific specialization in the first decade of the 20th century.