A panoramic view of the circumgalactic medium in the photoionized precipitation model

ABSTRACT We consider a model of the circumgalactic medium (CGM) in which feedback maintains a constant ratio of cooling time to free-fall time throughout the halo, so that the entire CGM is marginally unstable to multiphase condensation. This ‘precipitation model’ is motivated by observations of multiphase gas in the cores of galaxy clusters and the haloes of massive ellipticals. From the model, we derive the density and temperature profiles for the CGM around galaxies with masses similar to the Milky Way. After taking into consideration the geometrical position of our Solar system in the Milky Way, we show that the CGM model is consistent with observed O vi, O vii, O viii column densities and the ratio of O vii and O viii column densities only if temperature fluctuations with a lognormal dispersion σln T ∼ 0.6–1.0 are included. We show that O vi column densities observed around star-forming galaxies require systematically greater values of σln T than around passive galaxies, implying a connection between star formation in the disc and the state of the CGM. Photoionization by an extragalactic ultraviolet background radiation does not significantly change these CGM features for galaxies like the Milky Way but has much greater and significant effects on the CGM of lower mass galaxies.

Factors Influencing Sulforaphane Content in Broccoli Sprouts and Subsequent Sulforaphane Extraction

Broccoli sprouts contain 10–100 times higher levels of sulforaphane than mature plants, something that has been well known since 1997. Sulforaphane has a whole range of unique biological properties, and it is especially an inducer of phase 2 detoxication enzymes. Therefore, its use has been intensively studied in the field of health and nutrition. The formation of sulforaphane is controlled by the epithiospecifier protein, a myrosinase co-factor, which is temperature-specific. This paper studies the influence of temperature, heating time, the addition of myrosinase in the form of Raphanus sativus sprouts in constant ratio to broccoli sprouts, and other technological steps on the final sulforaphane content in broccoli sprout homogenates. These technological steps are very important for preserving sulforaphane in broccoli sprouts, but there are some limitations concerning the amount of sulforaphane. We focused, therefore, on the extraction process, using suitable β-cyclodextrin, hexane and ethanol, with the goal of increasing the amount of sulforaphane in the final extract, thus stabilizing it and reducing the required amount sulforaphane needed, e.g., as a dietary supplement.

Tight Localizations of Feedback Sets

The classical NP–hard feedback arc set problem (FASP) and feedback vertex set problem (FVSP) ask for a minimum set of arcs ε ⊆ E or vertices ν ⊆ V whose removal G ∖ ε, G ∖ ν makes a given multi–digraph G =( V , E ) acyclic, respectively. Though both problems are known to be APX–hard, constant ratio approximations or proofs of inapproximability are unknown. We propose a new universal O (| V || E | 4 )–heuristic for the directed FASP. While a ratio of r ≈ 1.3606 is known to be a lower bound for the APX–hardness, at least by empirical validation we achieve an approximation of r ≤ 2. Most of the relevant applications, such as circuit testing , ask for solving the FASP on large sparse graphs, which can be done efficiently within tight error bounds with our approach.

Evidence of terrestrial organic carbon inputs on Niger Delta Sea Shelf

The objective of this research is to determine the actual source of organic matter in the Niger Delta Sea Shelf (NDSS). Organic carbon (OC) and n-alkanes were investigated in the suspended matter (SM) and surfcial sediments of the Niger and Imo Rivers and the opposite Niger Delta Sea Shelf. Organic nitrogen and carbon isotope (δ13C) values were determined as additional parameters in the sediments. OC and n-alkane concentrations were highly variable. This variability was interpreted as the result of sources of materials from the inland basins and a complex sedimentation pattern involving the discharges of these two rivers. Using the constant ratio of high molecular weight odd n-alkanes to OC in both rivers, the estimated value of more than 70% of the OC preserved in shelf sediments were terrestrially-derived. This result was substantiated by the overall dominance of land-derived n-alkanes. A second approach using δ13C values and assuming binary dilution of riverine and marine OC led to the determined source of organic matter. Keywords: Organic carbon; δ13C; n-Alkanes; Niger River; Imo River; Niger Delta Sea Shelf.

Forecast for the second Covid-19 wave based on the improved SIR model with a constant ratio of recovery to infection rate

We start out by deriving simple analytic expressions for all measurable amounts of cases and fatalities during a pandemic evolution exhibiting multiple waves, described by the semi-time SIR model. The approximant shares all relevant features with the exact solution, including time and position of the peak of daily new infections, as well as the asymptotic behaviors at small and large times. We derive exact analytic expressions for the early doubling time, late half decay time, and a half-early peak law, characterizing the dynamical evolution. We show, in particular, how the asymmetry of the first epidemic wave and its exponential tails are affected by the initial conditions; a feature that has no analogue in the all-time SIR model. We apply the approach to available data from different continents. Our analysis reveals that the immunity is very strongly increasing during the 2nd wave, while it was still at a very moderate level of a few percent in several countries at the end of the first wave. The wave-specific SIR parameters describing the infection and recovery rates we find to behave in a similar fashion, while their ratio k was decreasing only by a about 5% for most countries. Still, an apparently moderate change of k can have significant consequences for the relevant numbers like the final amount of infected or deceased population. As we show, the probability for an additional wave is however low in several countries due to the fraction of immune inhabitants at the end of the 2nd wave, irrespective the currently ongoing vaccination efforts. We compare with alternate approaches.

Macroeconomic Modeling of the Relationship Between Price and Industry Proportions

The article aims to examine one of the most interesting, in the authors’ opinion, applications of the two-sector model of social technology to identify the relationship between the trajectories of the relative price and the relative share of the product in the total output based on the concept of Pareto optimal, or “efficient”, trajectories of economic growth (i.e. trajectories, each point of which belongs to the surface of production opportunities). Within the framework of this concept, the ratio of prices of individual products corresponds to the marginal rates of these products’ substitution. The rates depend on the product (sectoral) structure of GDP, on the one hand, and on the available labor resources and production assets, on the other. The relationship between the investment component of the output and the growth of funds gives rise to a family of efficient trajectories, in the sense indicated above. Each of the trajectories is characterized by the joint dynamics of industry and price proportions; therefore, the main problem of the study is to examine the general properties of such trajectories. The main feature of the model under consideration is the nonlinear production functions of industries. Even the simplest Cobb–Douglas specification generates the dynamics of the main variables of the model described by a nonlinear differential equation of the second order, which cannot be integrated in general form. Therefore, the analysis of the properties of effective trajectories (at least when specific parameters of trajectories are of interest, and not just general criteria for existence and stability) required the development of a program of numerical experiments on a computer, designed for a fairly extensive test of hypotheses and the convenience of presenting and analyzing the results. To begin with, a variant of the twosector model was chosen, in the future it is planned to expand it to a significantly larger number of sectors. The properties of effective trajectories with constant parameters were analyzed: the marginal rate of product substitution (constant price ratio), constant marginal rate of resource substitution (constant ratio of factor payment rates), constant ratio of net output of industries, constant share of investments in GDP, etc. General conclusions are obtained about the conditions for the convergence of such “iso-trajectories” to trajectories with a constant GDP growth rate and about the characteristics of stationary trajectories. Of greatest interest, in the author’s opinion, is the conclusion that the existence and stability of stationary trajectories is determined by the intersectoral ratio of the elasticities of the output with respect to the funds of the sectors under consideration: for an industry producing investment products, this parameter should be of lesser importance. The derived equation, which can be interpreted as an expression of a trend that determines the form of the relationship between the proportions of industry outputs and prices in the economy, opens the way to a meaningful macroeconomic analysis of the relationships between these proportions, depending on the configuration of the parameters of social technology Ai, αi, aij, B and scenarios of their changes over time.

The enthalpies of mixing of ternary liquid Ag-Ca-Ge alloys

Partial and integral enthalpies of mixing of the ternary Ag–Ca–Ge melts were determined for the first time by the high-temperature isoperibolic calorimetry at 1300–1550 K. The experiments were performed for six sections with a constant ratio of two components up to the molar fraction of the third component equal to 0.3. The enthalpies of mixing in this ternary system are exothermic values which increase in absolute value from the Ag corner of the concentration triangle towards the constituent binary Ca–Ge system. The minimum value of the integral enthalpy of mixing was obtained for Ca0.6Ge0.4 composition of the Ca–Ge binary system (about –58.00 kJ mol–1). The enthalpies of mixing of the ternary Ag–Ca–Ge melts are calculated for the whole concentration triangle by the Redlich-Kister-Muggianu method, taking into account the term of specific ternary interaction defined from our experimental data. The topology of the isoenthalpies of mixing is determined.