scholarly journals Trends in porosity сhanges of the unconsolidated part of ice ridge keel

2021 ◽  
Vol 67 (1) ◽  
pp. 44-59
Author(s):  
V. V. Kharitonov
Keyword(s):  
Lower Surface ◽  
Step Function ◽  
Average Density ◽  
Initial Porosity ◽  
Porosity Distribution ◽  
Average Porosity ◽  
Geographical Regions ◽  
Wide Range ◽  
Archimedes Force ◽  
Characteristic Features

An ice ridge is a special case of granular medium with a wide range of fractions. It represents a chaotic piling-up of blocks occurring under the action of gravity in the sail and due to the Archimedes force in the keel. An important characteristic of the internal structure of ice ridges is their porosity. Scientists from different countries have been dealing with this problem. First-year ice ridges are taken into consideration in Arctic and subarctic marine structural design, and the calculation of ice loads includes ridge porosity and strength, as well as other parameters. The aim of the present work is to discern the regularities of porosity distribution in the unconsolidated part of the keel with depth. Ice ridge porosity is identified by means of processing thermodrilling records. In this paper, porosity is interpreted as a step function equal to zero if there is ice at the point (x, y, z), and to one if there is no ice at the point (x, y, z). The author applies the model of compaction of the bulk medium under the influence of gravity, and, particularly for the keel, due to the Archimedes force. A zero depth corresponds to the lower surface of the keel, so each individual porosity distribution of the unconsolidated part of the keel at the drilling point must be shifted down until the maximum keel draft depth is reached in the region under consideration. After alignment, the step curves are averaged. The distance is measured up, starting from the depth of the maximum keel draft. The curve of the averaged porosity can be divided into segments reflecting the characteristic features of the distribution. According to the graphs, average porosity decreases exponentially. Ice ridges of several geographical regions are considered, and in each region is divided into groups by years of research. On the whole, 17 depth-wise distributions of the average porosity are obtained for seven regions. Each distribution was approximated according to the model, taking into account the average density of water and ice in the region. For each distribution, the values of compactibility and porosity at the zero depth, i. e. at the lower edge of the keel, were obtained; the second value only has mathematical sense. It is more convenient to consider the maximum value of the average porosity, which is taken as the initial porosity. With a probability of 90 %, the initial porosity is within the range of 0.450 ± 0.125. As the distance from the keel edge increases, the porosity curves converge to a fairly narrow range of values. At a distance of 12–14 m, this range is 0.07…0.12. The second parameter characterizing the porosity distribution in the unconsolidated part of the keel is compactibility. The steepness of the exponent approximating the average porosity curve depends on it, too. Compactibility is most affected by the strength of the ridged ice as well as the ice thickness. From the literature on the physical properties of ice it is known that as the temperature of ice increases, its strength decreases, and its plasticity increases. Thus, it can be concluded that compactibility is determined by the ice crystal structure as well the ice average temperature at the time of ridging — the warmer the ice, the higher the compactibility of the ice blocks in the keel.

Linear electrical properties of striated muscle fibres observed with intracellular electrodes

1964 ◽  
Vol 160 (978) ◽  
pp. 69-123 ◽  
Keyword(s):  
Electrical Properties ◽  
Striated Muscle ◽  
Surface Membrane ◽  
Fibre Surface ◽  
Step Function ◽  
Muscle Fibres ◽  
Appreciable Effect ◽  
Current Application ◽  
Current Path ◽  
Wide Range

The linear electrical properties of muscle fibres have been examined using intracellular electrodes for a. c. measurements and analyzing observations on the basis of cable theory. The measurements have covered the frequency range 1 c/s to 10 kc/s. Comparison of the theory for the circular cylindrical fibre with that for the ideal, one-dimensional cable indicates that, under the conditions of the experiments, no serious error would be introduced in the analysis by the geometrical idealization. The impedance locus for frog sartorius and crayfish limb muscle fibres deviates over a wide range of frequencies from that expected for a simple model in which the current path between the inside and the outside of the fibre consists only of a resistance and a capacitance in parallel. A good fit of the experimental results on frog fibres is obtained if the inside-outside admittance is considered to contain, in addition to the parallel elements R m = 3100 Ωcm 2 and C m = 2.6 μF/cm 2 , another path composed of a resistance R e = 330 Ωcm 2 in series with a capacitance C e = 4.1 μF/cm 2 , all referred to unit area of fibre surface. The impedance behaviour of crayfish fibres can be described by a similar model, the corresponding values being R m = 680 Ωcm 2 , C m = 3.9 μF/cm 2 , R e = 35 Ωcm 2 , C e = 17 μF/cm 2 . The response of frog fibres to a step-function current (with the points of voltage recording and current application close together) has been analyzed in terms of the above two-time constant model, and it is shown that neglecting the series resistance would have an appreciable effect on the agreement between theory and experiment only at times less than the halftime of rise of the response. The elements R m and C m are presumed to represent properties of the surface membrane of the fibre. R e and C e are thought to arise not at the surface, but to be indicative of a separate current path from the myoplasm through an intracellular system of channels to the exterior. In the case of crayfish fibres, it is possible that R e (when referred to unit volume) would be a measure of the resistivity of the interior of the channels, and C e the capacitance across the walls of the channels. In the case of frog fibres, it is suggested that the elements R e , C e arise from the properties of adjacent membranes of the triads in the sarcoplasmic reticulum . The possibility is considered that the potential difference across the capacitance C e may control the initiation of contraction.

Theoretical and practical aspects in determining the current geochemical status of the Crimean peninsula and anthropogenic risk to public health

2021 ◽  
Author(s):  
Elena Evstafeva ◽  
Svetlana Tymchenko ◽  
Anna Bogdanova ◽  
Olga Zalata ◽  
Yuliia Boyarinceva ◽  
...  
Keyword(s):  
Human Body ◽  
Negative Impact ◽  
Chemical Elements ◽  
Ecological Monitoring ◽  
Crimean Peninsula ◽  
Mercury Analysis ◽  
Geographical Regions ◽  
Wide Range ◽  
Biological Substrates ◽  
Cadmium Selenium

<p>The implementation of basic principles of medical and ecological monitoring programs in Crimea previously reported in EGU proceedings consists of determining the content of a wide range of toxic, essential and rare earth elements in various biological substrates: soil, plants, water, human body. Biosubstrates are sampled in different locations with contrast natural and anthropogenic conditions: urbanized-rural, industrial-agricultural, natural resources. Lichens and poplar leaves are used as indicators of environmental contamination, particularly atmospheric pollution; liquid precipitation is used as an indicator showing the negative impact of air pollution on ecosystems; hair is used as an indicator of the total body intake of chemical elements. The update of databases, on some of the territories (Simferopol, Sevastopol, geographical regions with different soil characteristics, etc.) with regard to some of the elements (mercury, lead, cadmium, selenium, etc.) at this stage allowed to determine their biogeochemical status in conditions of intensive growth of anthropogenic load in recent years, and to compare it with the elemental status of the humans living in this territory. The databases for other types of territories continue to be extended, the relationship between morbidity to estimate of the environmental burden of disease for environmentally determined diseases (neurodegenerative, endocrine, respiratory, etc.) and chemical load on the territories, based on USEtox model; the functional state of target systems (nervous, immune, cardiovascular) and level of chemical elements in the human body and the overall elemental imbalance, is established. This has provided us with a degree of understanding on how the degree of population and individual health risk could be determined.</p><p>Mercury analysis was funded by RFBR according to the research project № 18-29-24212\19 entitled “Development of neutralization of mercury-containing waste without heating and the formation of wastewater”, 2018–2021 years; elemental composition was possible to determine due to RFBR project № 18-45-920042\20 entitled “Bioecological monitoring of heavy metals at board of Black Sea of Crimea”, 2018–2020 years. Physiological part of research was possible to accomplish due to funds by the V.I. Vernadsky Crimean Federal University (Project No VG2019/15, АААА-А20-120012090158-7).</p>

Rice (Oryza sativa L.) germplasm with better seedling emergence under direct sowing in flooded paddy field

2018 ◽  
Vol 16 (4) ◽  
pp. 352-358 ◽  
Author(s):  
Junichi Kashiwagi ◽  
Koji Hamada ◽  
Yutaka Jitsuyama
Keyword(s):  
Paddy Field ◽  
Oryza Sativa L ◽  
Seedling Emergence ◽  
Screening Method ◽  
Paddy Fields ◽  
Rice Germplasm ◽  
Geographical Regions ◽  
Wide Range ◽  
Cultivation Practice ◽  
Direct Sowing

AbstractDirect sowing of rice in a flooded paddy field is a beneficial cultivation practice for water use and labour efficiency, compared to the transplanted cultivation. However, a drastic reduction in seedling emergence under flooded paddy fields is a serious constraint especially when the seeds fell at deeper soil layers. Suitable rice germplasm for the direct sowing in flooded paddy fields could ensure the success of this cultivation practice. Instead of laborious field-based screening systems, a pot-based screening method was adopted for simplicity and efficient evaluation of seedling emergence of a subset of world rice germplasm (n = 75) at different sowing depths. As a result, two rice genotypes, ‘Vary Futsi’ (landrace from Madagascar, non-glutinous, subspecies Indica) and ‘Dahonggu’ (landrace from China, non-glutinous, subspecies Indica), with consistently better seedling emergence were identified from a wide range of rice germplasm. These genotypes could serve as excellent parents for the breeding program in developing new rice cultivars with the improved seedling emergence in flooded paddy fields. There were no significant differences in the seedling emergence rate in flooded paddy conditions among the groups from various agro-geographical regions.

scholarly journals DISTRIBUTION OF BRYOPHYTES OF AGALYK BASIN (KARATEPA MOUNTAINS OF ZERAVSHAN MOUNTAIN RANGE)

2015 ◽  
Vol 4 (2) ◽  
pp. 80-82
Author(s):  
Holmurod Akimovich Zhalov
Keyword(s):  
Species Composition ◽  
Point Of View ◽  
Mountain Range ◽  
Decayed Wood ◽  
Moss Species ◽  
Comparative Analyses ◽  
Wide Range ◽  
Identification Of Species ◽  
Characteristic Features ◽  
Research Period

From bryological point of view Zeravshan mountain range remains one of the least studied region. Identification of species composition of true mosses and their ecological-biological peculiarities were not earlier aimed for this region. In the territory of Agalyk basin Karatepa mountains can be divided into four types of substrates where moss species occur: soil, bark of living trees, decayed wood, stones. Characteristics of substrate groups become complicated due to wide range of ecological valency of moss species. Most species select not only one, but several substrates for their settling. During the research period in the soils of Agaliksay basin 20 species were recorded belonging to 13 genera and 10 family. On decayed wood 9 species were recorded belonging to 7 genera and 5 family. On the bark of living trees 15 moss species were recorded belonging to 8 genera and 6 family. Epilyte bryophytes occurred on rocky substrates. On rocky substrates of Agaliksay basin 34 moss species were recorded from 16 genera and 13 family. On the basis of results obtained during the study of substrate groups of mosses in Agaliksay basin, we have conducted comparative analyses of studied substrate groups with the purpose of determining their characteristic features.

scholarly journals Myosin MyTH4-FERM structures highlight important principles of convergent evolution

2016 ◽  
Vol 113 (21) ◽  
pp. E2906-E2915 ◽  
Author(s):  
Vicente José Planelles-Herrero ◽  
Florian Blanc ◽  
Serena Sirigu ◽  
Helena Sirkia ◽  
Jeffrey Clause ◽  
...  
Keyword(s):  
Binding Sites ◽  
Convergent Evolution ◽  
Tail Domain ◽  
The Core ◽  
Binding Partners ◽  
The Social ◽  
Wide Range ◽  
Membrane Protrusions ◽  
Characteristic Features ◽  
Multifunctional Platform

Myosins containing MyTH4-FERM (myosin tail homology 4-band 4.1, ezrin, radixin, moesin, or MF) domains in their tails are found in a wide range of phylogenetically divergent organisms, such as humans and the social amoeba Dictyostelium (Dd). Interestingly, evolutionarily distant MF myosins have similar roles in the extension of actin-filled membrane protrusions such as filopodia and bind to microtubules (MT), suggesting that the core functions of these MF myosins have been highly conserved over evolution. The structures of two DdMyo7 signature MF domains have been determined and comparison with mammalian MF structures reveals that characteristic features of MF domains are conserved. However, across millions of years of evolution conserved class-specific insertions are seen to alter the surfaces and the orientation of subdomains with respect to each other, likely resulting in new sites for binding partners. The MyTH4 domains of Myo10 and DdMyo7 bind to MT with micromolar affinity but, surprisingly, their MT binding sites are on opposite surfaces of the MyTH4 domain. The structural analysis in combination with comparison of diverse MF myosin sequences provides evidence that myosin tail domain features can be maintained without strict conservation of motifs. The results illustrate how tuning of existing features can give rise to new structures while preserving the general properties necessary for myosin tails. Thus, tinkering with the MF domain enables it to serve as a multifunctional platform for cooperative recruitment of various partners, allowing common properties such as autoinhibition of the motor and microtubule binding to arise through convergent evolution.

Ivan Kavaleridze`s dramaturgy on the Sumy stage

2021 ◽  
Author(s):  
D.V. Budianskyi
Keyword(s):  
Large Scale ◽  
Musical Comedy ◽  
Historical Figures ◽  
Wide Range ◽  
Socialist Realist ◽  
History Of ◽  
Characteristic Features ◽  
Old Men ◽  
The Impact ◽  
First Time

The characteristic features of I. Kavaleridze’s drama is considered in the article. It is noted that there are signs of the artist’s individuality, attraction to expressionist forms, artistic techniques characteristic for the art of sculpture: symbolism, monumentality, hyperbole. I. Kavaleridze was well versed in the drama laws, understood the specifics of the stage events construction, had a large arsenal of literary means, thanks to which the characters’ monologues and dialogues were extremely expressive and colorful. In his work, he implemented original solutions that were ahead of time. Therefore, many of the artist’s ideas and achievements received due recognition only after his death. I. Kavaleridze’s creative heritage covers a wide range of both purely artistic and general philosophical problems. Among them the formation of the era of modernism and its features in the Ukrainian art of the early XX century, the impact of revolutionary ideas on the work of the 1920s, the role of spiritual leaders of the Ukrainian people T. Shevchenko and G. Skovoroda in the formation of national consciousness, political and ideological pressure on figurative art language and the formation of a socialist-realist canon, etc. The analysis of the productions of I. Kavalerizde’s plays “The First Furrow” and “Gregory and Paraskeva” on the stage of the Mykhailo Shchepkin Sumy Theater of Drama and Musical Comedy in 1970-1972. The article notes that these plays were staged in Sumy for the first time in the history of Ukrainian theater. The premiere of “The First Furrow” (the play was called “Old Men”) took place on March 19, 1970. The figure of the national genius Hryhoriy Skov oroda was als o embodied for the first time on t he stage in Sumy in th e play “Hryhoriy and Paraskeva”. It premiered on October 21, 1972. I. Rybchynsky, Honored Artist of the USSR, performed the production. Creating generalized historical outlines of people’s life, features of life at that time, depicting psychological portraits of people in various, sometimes-dramatic collisions, in the productions of I. Kavaleridze’s plays on the Sumy stage the emphasis was on universal values such as virtue, love. The main character was the Ukrainian people, who nurtured such large-scale historical figures, gave them strength and wisdom for great achievements. Based on publications in periodicals of that time, memoirs of Ukrainian directors, the peculiarities of the director’s interpretation, stenographic and musical design of these plays on the Sumy stage are considered. Considerable attention is paid to the analysis of acting works in I. Kavaleridze’s plays. In particular, the peculiarities of the actor’s embodiment of the image of the national genius Hryhoriy Skovoroda on the stage are presented. It is noted that I. Kavaleridze’s plays, created in a difficult political, social and ideological context, are rightly considered to be highly artistic works of Ukrainian drama. Their staging was carried out on various theatrical stages, including Mykhailo Shchepkin Sumy Theater of Drama and Musical Comedy is an important page of national theatrical art.

The taxonomic status of the genus Rubidgea

Bothalia ◽  
1977 ◽  
Vol 12 (2) ◽  
pp. 313-317 ◽  
Author(s):  
Éva Kovács-Endrődy
Keyword(s):  
South Africa ◽  
Type Species ◽  
Taxonomic Status ◽  
Lower Surface ◽  
Carbonaceous Shale ◽  
Single Leaf ◽  
Wide Range

The genus Rubidgea Tate of the fossil family Glossopteridaceae was reduced to a synonym of Glossopteris by Seward (1907). Seward’s conclusion is now confirmed by a study of a wide range of imprints from a quarry near Hammanskraal, South Africa. The upper and lower surface imprints of a single leaf found on a split fragment of carbonaceous shale provides the main evidence presented. The finely striated upper surface imprint of the leaf could be identified with  Rubidgea, whereas the lower surface imprint represents the typical strong venation of a  Glossopteris. The type species of  Rubidgea is transferred to  Glossopteris as  G. mackayi (Tate) Kovacs comb. nov. The characteristics of upper and lower surface imprints of a number of  Glossopteris species are discussed.

scholarly journals Supramolecular Fuzziness of Intracellular Liquid Droplets: Liquid–Liquid Phase Transitions, Membrane-Less Organelles, and Intrinsic Disorder

Molecules ◽  
2019 ◽  
Vol 24 (18) ◽  
pp. 3265 ◽  
Author(s):  
Vladimir N. Uversky
Keyword(s):  
Phase Transitions ◽  
Liquid Phase ◽  
Intrinsically Disordered Proteins ◽  
Intrinsically Disordered Protein ◽  
Disordered Proteins ◽  
Bacterial Cells ◽  
Liquid Droplets ◽  
Intrinsically Disordered ◽  
Wide Range ◽  
Characteristic Features

Cells are inhomogeneously crowded, possessing a wide range of intracellular liquid droplets abundantly present in the cytoplasm of eukaryotic and bacterial cells, in the mitochondrial matrix and nucleoplasm of eukaryotes, and in the chloroplast’s stroma of plant cells. These proteinaceous membrane-less organelles (PMLOs) not only represent a natural method of intracellular compartmentalization, which is crucial for successful execution of various biological functions, but also serve as important means for the processing of local information and rapid response to the fluctuations in environmental conditions. Since PMLOs, being complex macromolecular assemblages, possess many characteristic features of liquids, they represent highly dynamic (or fuzzy) protein–protein and/or protein–nucleic acid complexes. The biogenesis of PMLOs is controlled by specific intrinsically disordered proteins (IDPs) and hybrid proteins with ordered domains and intrinsically disordered protein regions (IDPRs), which, due to their highly dynamic structures and ability to facilitate multivalent interactions, serve as indispensable drivers of the biological liquid–liquid phase transitions (LLPTs) giving rise to PMLOs. In this article, the importance of the disorder-based supramolecular fuzziness for LLPTs and PMLO biogenesis is discussed.

Serotonin differentially affects morph-specific behavior in divergent populations of a horned beetle

2019 ◽  
Vol 31 (2) ◽  
pp. 352-360 ◽  
Author(s):  
Keeley D Newsom ◽  
Armin P Moczek ◽  
Daniel B Schwab
Keyword(s):  
Critical Role ◽  
Population Divergence ◽  
Aggressive Behaviors ◽  
Onthophagus Taurus ◽  
Male Condition ◽  
Wide Range ◽  
Behavioral Responsiveness ◽  
Serotonin Signaling ◽  
Characteristic Features ◽  
Serotonin Biosynthesis

Abstract Associations between animal weapons and corresponding aggressive behaviors are among the most characteristic features of species, yet at the same time their co-expression is itself often strongly dependent on context, such as male condition or population ecology. Yet the mechanisms that modulate associations between aggression, morphology, and biological context remain poorly understood. The biogenic amine serotonin has been shown to regulate a wide range of aggressive and morph-specific behaviors in diverse insect species. However, the extent to which serotonin may coordinate the expression of behavior with morphology across biological contexts remains unclear. In this study, we pharmacologically increased serotonin biosynthesis in males of the polyphenic beetle, Onthophagus taurus, and assessed how this manipulation affects both aggressive and non-aggressive behaviors in alternative fighter and sneaker morphs, as well as in males derived from two rapidly diverging populations characterized by disparate levels of competition for mates. We find (i) that enhancing serotonin biosynthesis increases most measures of aggressive behaviors, but influences only a subset of nonaggressive behaviors, (ii) that similar serotonin-mediated behavioral changes manifest in both morphs within populations more often than just a single morph, and (iii) that males derived from the two focal populations have diverged in their behavioral responsiveness to serotonin up-regulation. Collectively, our study suggests that serotonin signaling plays a critical role in the regulation of male behavior and its evolution, including in the context of rapid, short-term population divergence.

Influence of Mechanical Surface Treatments on the Fatigue Performance of the Gamma TiAl Alloy Ti-45Al-9Nb-0.2C

2007 ◽  
Vol 539-543 ◽  
pp. 1553-1558 ◽  
Author(s):  
Janny Lindemann ◽  
Anja Kutzsche ◽  
Michael Oehring ◽  
Fritz Appel
Keyword(s):  
Surface Roughness ◽  
Shot Peening ◽  
Tial Alloy ◽  
Elevated Temperatures ◽  
Lower Surface ◽  
Fatigue Performance ◽  
Ambient Temperatures ◽  
Roller Burnishing ◽  
Compressive Stresses ◽  
Wide Range

The effect of shot peening and roller burnishing on the fatigue performance of the γ(TiAl) alloy Ti-45Al-9Nb-0.2C was investigated over a wide range of processing intensities. At optimized conditions shot peening and roller burnishing can markedly improve the fatigue strength at ambient temperatures. For temperatures above 650 °C, the residual compressive stresses induced by shot peening and roller burnishing quickly relax. This indicates that, at elevated temperatures, surface roughness and dislocation strengthening become more important for the fatigue performance of mechanically surface-treated components. Roller burnishing leads to much lower surface roughness than shot peening, resulting in more effective improvement of high temperature fatigue performance. However, surface strengthening by shot peening can also be beneficial for the fatigue performance at elevated temperatures, when the surface roughness is reduced by subsequent polishing.

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