scholarly journals Efficient flocking: metric versus topological interactions

2021 ◽  
Vol 8 (9) ◽  
Author(s):  
Vijay Kumar ◽  
Rumi De
Keyword(s):  
Threshold Value ◽  
Field Studies ◽  
Particle Model ◽  
Interaction Radius ◽  
Nearest Neighbours ◽  
Wide Range ◽  
Living Organisms ◽  
Ordered Motion ◽  
Metric Distance ◽  
Ordered State

Flocking is a fascinating phenomenon observed across a wide range of living organisms. We investigate, based on a simple self-propelled particle model, how the emergence of ordered motion in a collectively moving group is influenced by the local rules of interactions among the individuals, namely, metric versus topological interactions as debated in the current literature. In the case of the metric ruling, the individuals interact with the neighbours within a certain metric distance; by contrast, in the topological ruling, interaction is confined within a number of fixed nearest neighbours. Here, we explore how the range of interaction versus the number of fixed interacting neighbours affects the dynamics of flocking in an unbounded space, as observed in natural scenarios. Our study reveals the existence of a certain threshold value of the interaction radius in the case of metric ruling and a threshold number of interacting neighbours for the topological ruling to reach an ordered state. Interestingly, our analysis shows that topological interaction is more effective in bringing the order in the group, as observed in field studies. We further compare how the nature of the interactions affects the dynamics for various sizes and speeds of the flock.

scholarly journals Efficient Flocking: Metric Versus Topological Interactions

2021 ◽  
Author(s):  
Vijay Kumar ◽  
Rumi De
Keyword(s):  
Threshold Value ◽  
Field Studies ◽  
Particle Model ◽  
Interaction Radius ◽  
Nearest Neighbours ◽  
Wide Range ◽  
Living Organisms ◽  
Ordered Motion ◽  
Metric Distance ◽  
Ordered State

Flocking is a fascinating phenomenon observed across a wide range of living organisms. We investigate, based on a simple self-propelled particle model, how the emergence of ordered motion in a collectively moving group is influenced by the local rules of interactions among the individuals, namely, metric versus topological interactions as debated over in the current literature. In the case of the metric ruling, the individuals interact with the neighbours within a certain metric distance; in contrast, in the topological ruling, interaction is confined within a number of fixed nearest neighbours. Here, we explore how the range of interaction versus the number of fixed interacting neighbours affects the dynamics of flocking in an unbounded space, as observed in natural scenarios. Our study reveals the existence of a certain threshold value of the interaction radius in the case of metric ruling and a threshold number of interacting neighbours for the topological ruling to reach an ordered state. Interestingly, our analysis shows that topological interaction is more effective in bringing the order in the group, as observed in field studies. We further compare how the nature of the interactions affects the dynamics for various sizes and speeds of the flock.

scholarly journals Graphene Oxide-Based Nanofiltration for Hg Removal from Wastewater: A Mini Review

Membranes ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 269
Author(s):  
Megawati Zunita
Keyword(s):  
Graphene Oxide ◽  
Negative Impact ◽  
Treatment Area ◽  
Functionalized Graphene Oxide ◽  
Flexible Membrane ◽  
High Mechanical Strength ◽  
Wide Range ◽  
Living Organisms ◽  
Filtration Properties ◽  
High Chemical Stability

Mercury (Hg) is one of heavy metals with the highest toxicity and negative impact on the biological functions of living organisms. Therefore, many studies are devoted to solving the problem of Hg separation from wastewater. Membrane-based separation techniques have become more preferable in wastewater treatment area due to their ease of operation, mild conditions and also more resistant to toxic pollutants. This technique is also flexible and has a wide range of possibilities to be integrated with other techniques. Graphene oxide (GO) and derivatives are materials which have a nanostructure can be used as a thin and flexible membrane sheet with high chemical stability and high mechanical strength. In addition, GO-based membrane was used as a barrier for Hg vapor due to its nano-channels and nanopores. The nano-channels of GO membranes were also used to provide ion mobility and molecule filtration properties. Nowadays, this technology especially nanofiltration for Hg removal is massively explored. The aim of the review paper is to investigate Hg removal using functionalized graphene oxide nanofiltration. The main focus is the effectiveness of the Hg separation process.

The role of slow magnetostrophic waves in dipole formation in rapidly rotating dynamos

2021 ◽  
Author(s):  
Aditya Varma ◽  
Binod Sreenivasan
Keyword(s):  
Magnetic Field ◽  
Threshold Value ◽  
Dipole Field ◽  
Wave Frequency ◽  
Alfven Wave ◽  
Inertial Waves ◽  
Axial Dipole ◽  
Wide Range ◽  
The Magnetic Field

<p>It is known that the columnar structures in rapidly rotating convection are affected by the magnetic field in ways that enhance their helicity. This may explain the dominance of the axial dipole in rotating dynamos. Dynamo simulations starting from a small seed magnetic field have shown that the growth of the field is accompanied by the excitation of convection in the energy-containing length scales. Here, this process is studied by examining axial wave motions in the growth phase of the dynamo for a wide range of thermal forcing. In the early stages of evolution where the field is weak, fast inertial waves weakly modified by the magnetic field are abundantly present. As the field strength(measured by the ratio of the Alfven wave to the inertial wave frequency) exceeds a threshold value, slow magnetostrophic waves are spontaneously generated. The excitation of the slow waves coincides with the generation of helicity through columnar motion, and is followed by the formation of the axial dipole from a chaotic, multipolar state. In strongly driven convection, the slow wave frequency is attenuated, causing weakening of the axial dipole intensity. Kinematic dynamo simulations at the same parameters, where only fast inertial waves are present, fail to produce the axial dipole field. The dipole field in planetary dynamos may thus be supported by the helicity from slow magnetostrophic waves.</p>

BIODIVERSITI DAN PEMULIHARAAN TERUMBU KARANG DI TIGA BUAH PULAU, MELAKA (Biodiversity and Conservation of Coral Reefs in Three Islands in Malacca)

2021 ◽  
Vol 22 (1) ◽  
pp. 180-197
Author(s):  
SYAIMAK ISMAIL ◽  
MOHAMAD SAUPI BIN ISMAIL ◽  
MUHAMMAD SAIFUL ISLAM ISMAIL ◽  
AEMY AZIZ
Keyword(s):  
Coral Reefs ◽  
Biodiversity Conservation ◽  
Soft Coral ◽  
Good Condition ◽  
Scuba Diving ◽  
Field Studies ◽  
The State ◽  
Hard Coral ◽  
Wide Range ◽  
State Museum

In the state of Melaka, there are eighteen islands recorded by the Melaka State Museum Corporation (PERZIM). Part of this island serves as a tourist island, and developed islands are also uninhabited islands. However, three islands are recorded to have amazing coral reefs that are still in good condition. The Penang Batu Maung Fisheries Research Institute (AkuaTAR) has conducted a study on the biodiversity of coral reefs around the waters of Pulau Dodol, Pulau Serimbun, and Pulau Undan. AkuaTAR researchers are using scuba diving methods, and at the same time, they did conservation on coral reefs that have been identified in the waters of the Straits of Melaka. The objective of this study is to record the types of community forms such as living corals and identify the species of coral reefs found in three islands in the state of Melaka in Pulau Undan, Pulau Dodol, and Pulau Serimbun. The study also implemented method observation by conducting field studies on the islands involved by doing scuba diving. Results and discussion of the search, these three islands are located in very clean, uninhabited waters. They have a wide range of coral biodiversity using soft coral reefs and hard coral reefs. The study also found that the three islands in the state have the largest coral reefs in the waters of the Straits of Melaka. Keywords: Biodiversity; Conservation; Coral; Three island; Melaka

scholarly journals Wintertime aerosol chemical composition, volatility, and spatial variability in the greater London area

2016 ◽  
Vol 16 (2) ◽  
pp. 1139-1160 ◽  
Author(s):  
L. Xu ◽  
L. R. Williams ◽  
D. E. Young ◽  
J. D. Allan ◽  
H. Coe ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Solid Fuel ◽  
Field Studies ◽  
Rural Site ◽  
Urban Site ◽  
High Temporal Resolution ◽  
Volatile Organics ◽  
Aerosol Mass ◽  
Rural And Urban ◽  
Wide Range

Abstract. The composition of PM1 (particulate matter with diameter less than 1 µm) in the greater London area was characterized during the Clean Air for London (ClearfLo) project in winter 2012. Two high-resolution time-of-flight aerosol mass spectrometers (HR-ToF-AMS) were deployed at a rural site (Detling, Kent) and an urban site (North Kensington, London). The simultaneous and high-temporal resolution measurements at the two sites provide a unique opportunity to investigate the spatial distribution of PM1. We find that the organic aerosol (OA) concentration is comparable between the rural and urban sites, but the contribution from different sources is distinctly different between the two sites. The concentration of solid fuel OA at the urban site is about twice as high as at the rural site, due to elevated domestic heating in the urban area. While the concentrations of oxygenated OA (OOA) are well-correlated between the two sites, the OOA concentration at the rural site is almost twice that of the urban site. At the rural site, more than 70 % of the carbon in OOA is estimated to be non-fossil, which suggests that OOA is likely related to aged biomass burning considering the small amount of biogenic SOA in winter. Thus, it is possible that the biomass burning OA contributes a larger fraction of ambient OA in wintertime than what previous field studies have suggested. A suite of instruments was deployed downstream of a thermal denuder (TD) to investigate the volatility of PM1 species at the rural Detling site. After heating at 250 °C in the TD, 40 % of the residual mass is OA, indicating the presence of non-volatile organics in the aerosol. Although the OA associated with refractory black carbon (rBC; measured by a soot-particle aerosol mass spectrometer) only accounts for < 10 % of the total OA (measured by a HR-ToF-AMS) at 250 °C, the two measurements are well-correlated, suggesting that the non-volatile organics have similar sources or have undergone similar chemical processing as rBC in the atmosphere. Although the atomic O : C ratio of OOA is substantially larger than that of solid fuel OA and hydrocarbon-like OA, these three factors have similar volatility, which is inferred from the change in mass concentration after heating at 120 °C. Finally, we discuss the relationship between the mass fraction remaining (MFR) of OA after heating in the TD and atomic O : C of OA and find that particles with a wide range of O : C could have similar MFR after heating. This analysis emphasizes the importance of understanding the distribution of volatility and O : C in bulk OA.

scholarly journals Characterization of an Insoluble and Soluble Form of Melanin Produced by Streptomyces cavourensis SV 21, a Sea Cucumber Associated Bacterium

Marine Drugs ◽  
2022 ◽  
Vol 20 (1) ◽  
pp. 54
Author(s):  
Joko Tri Wibowo ◽  
Matthias Y. Kellermann ◽  
Lars-Erik Petersen ◽  
Yustian R. Alfiansah ◽  
Colleen Lattyak ◽  
...  
Keyword(s):  
Biological Properties ◽  
Water Soluble ◽  
Soluble Form ◽  
Wide Range ◽  
Biological Form ◽  
Insoluble Form ◽  
New Perspective ◽  
Living Organisms ◽  
Purification Protocol

Melanin is a widely distributed and striking dark-colored pigment produced by countless living organisms. Although a wide range of bioactivities have been recognized, there are still major constraints in using melanin for biotechnological applications such as its fragmentary known chemical structure and its insolubility in inorganic and organic solvents. In this study, a bacterial culture of Streptomyces cavourensis SV 21 produced two distinct forms of melanin: (1) a particulate, insoluble form as well as (2) a rarely observed water-soluble form. The here presented novel, acid-free purification protocol of purified particulate melanin (PPM) and purified dissolved melanin (PDM) represents the basis for an in-depth comparison of their physicochemical and biological properties, which were compared to the traditional acid-based precipitation of melanin (AM) and to a synthetic melanin standard (SM). Our data show that the differences in solubility between PDM and PPM in aqueous solutions may be a result of different adjoining cation species, since the soluble PDM polymer is largely composed of Mg2+ ions and the insoluble PPM is dominated by Ca2+ ions. Furthermore, AM shared most properties with SM, which is likely attributed to a similar, acid-based production protocol. The here presented gentler approach of purifying melanin facilitates a new perspective of an intact form of soluble and insoluble melanin that is less chemical altered and thus closer to its original biological form.

scholarly journals The signalling role of ROS in the regulation of seed germination and dormancy

2019 ◽  
Vol 476 (20) ◽  
pp. 3019-3032 ◽  
Author(s):  
Christophe Bailly
Keyword(s):  
Seed Germination ◽  
Oxygen Species ◽  
Direct Oxidation ◽  
Cellular Events ◽  
Seed Physiology ◽  
Spatiotemporal Regulation ◽  
Wide Range ◽  
Living Organisms ◽  
Hormone Signalling

Abstract Reactive oxygen species (ROS) are versatile compounds which can have toxic or signalling effects in a wide range living organisms, including seeds. They have been reported to play a pivotal role in the regulation of seed germination and dormancy but their mechanisms of action are still far from being fully understood. In this review, we sum-up the major findings that have been carried out this last decade in this field of research and which altogether shed a new light on the signalling roles of ROS in seed physiology. ROS participate in dormancy release during seed dry storage through the direct oxidation of a subset of biomolecules. During seed imbibition, the controlled generation of ROS is involved in the perception and transduction of environmental conditions that control germination. When these conditions are permissive for germination, ROS levels are maintained at a level which triggers cellular events associated with germination, such as hormone signalling. Here we propose that the spatiotemporal regulation of ROS production acts in concert with hormone signalling to regulate the cellular events involved in cell expansion associated with germination.

scholarly journals COMPLEX ASSESSMENT OF BIOSOLID FOR AGRICULTURE USING LIVING ORGANISMS UNDER LABORATORY CONDITIONS

AGROFOR ◽  
2020 ◽  
Vol 5 (3) ◽  
Author(s):  
Ksenia PONOGAYBO ◽  
Liudmila VORONINA
Keyword(s):  
Tetrahymena Pyriformis ◽  
Integrated Approach ◽  
Water Soluble ◽  
Municipal Sewage ◽  
Municipal Sewage Sludge ◽  
Soil Extraction ◽  
Luminescent Bacteria ◽  
Wide Range ◽  
Test Organisms ◽  
Living Organisms

The use of biosolids (treated municipal sewage sludge) as a fertilizer is the best way of their disposal. However, not all of them are suitable for use as a fertilizer. Biosolids should be subject to mandatory laboratory control to confirm their safety. Two directions of research on biosolids are being improved: chemical and biological. Chemical analysis methods allow us to determine the qualitative composition of complex waste. The biological approach (use of living organisms) allows us to estimate the total toxicity of all the components. Accordingly, a distinctive characteristic of biological methods is the integrated approach. We examined biosolid extract using a wide range of bioassay methods. As test organisms, we took Daphnia magna Straus, Paramecium caudatum Ehrenberg, Tetrahymena pyriformis, luminescent bacteria Escherichia coli. In addition, a phytotest was carried out on the culture of Avena sativa L. and Raphanus sativus L. None of the tests revealed a high toxicity of biosolid. Biosolid safety was confirmed by a low content of potentially toxic water-soluble elements – (μg /l): Al3+ – 980; Ba2+ – 19; B – 140; Mn – 360; Cu – 61; As – 57; Ni – 200; Pb – 1,4; Sr2+ – 302; Cr – 18; Zn2+ – 310; Co – 30; Mo – 56; (mg/l): Na+ – 16,8; Fe – 1,0. The bioassay methods make it possible to give an indicative safety assessment of this type of object by the effect of readily soluble (readily available) components from this object on living organisms and plants. The use of bioassay methods using soil extraction as a control tool allows to take into account the combined effect of the presence in the extraction of not only toxic elements that suppress the vital activity of organisms, but also of elements that attract and stimulate the activity of test-organisms.

scholarly journals A IMPORTÂNCIA DAS CUMARINAS PARA A QUÍMICA MEDICINAL E O DESENVOLVIMENTO DE COMPOSTOS BIOATIVOS NOS ÚLTIMOS ANOS

Química Nova ◽  
2020 ◽  
Author(s):  
Daiana Franco ◽  
Thiago Pereira ◽  
Felipe Vitorio ◽  
Nathalia Nadur ◽  
Renata Lacerda ◽  
...  
Keyword(s):  
Chemical Space ◽  
Biological Activities ◽  
Research Projects ◽  
Wide Range ◽  
Non Covalent Interactions ◽  
Iupac Nomenclature ◽  
Living Organisms ◽  
Coumarin Compounds ◽  
New Treatments ◽  
Covalent Interactions

Coumarins are natural products characterized as 2H-chromen-2-one, according to IUPAC nomenclature, largely distributed in plants, as well as, in species of fungi and bacteria. Nowadays, many synthetic procedures allow the discovery of coumarins with expanded chemical space. The ability to exert non-covalent interactions with many enzymes an receptors in living organisms lead the coumarins to exhibit a wide range of biological activities and applications. Then, this manuscript provides an overview of the use of coumarin compounds in medicinal chemistry in treating many diseases. Important examples of the last years have been selected concerning the activities of coumarins as anticoagulant, anticancer, antioxidant, antiviral, antidiabetics, anti-inflammatory, antibacterial, antifungal, and anti-neurodegenerative agents. Thus, this work aims at contributing to the development of new rational research projects searching for new treatments and bioactive compounds for many pathologies using coumarin derivatives.

scholarly journals Occurrence of the amphibians in the Volga, Don River basins and adjacent territories (Russia): research in 1996-2020

2020 ◽  
Vol 8 ◽  
Author(s):  
Alexander Ruchin ◽  
Oleg Artaev ◽  
Elvira Sharapova ◽  
Oleg Ermakov ◽  
Renat Zamaletdinov ◽  
...  
Keyword(s):  
Molecular Genetic ◽  
Genetic Research ◽  
Russian Plain ◽  
Amphibian Species ◽  
Volga River ◽  
Wide Range ◽  
Don River ◽  
Global Biodiversity ◽  
Single Standard ◽  
Living Organisms

Knowledge about the distribution of living organisms on Earth is very important for many areas of biological science and understanding of the surrounding world. However, much of the existing distributional data are scattered throughout a multitude of sources, such as taxonomic publications, checklists and natural history collections and often, bringing them together is difficult. A very successful attempt to solve this problem is the GBIF project, which allows a huge number of researchers to publish data in one place in a single standard. Our dataset represents a significant addition to the occurrences of amphibians in the Volga, Don riverine basins and adjacent territories. The dataset contains up-to-date information on amphibian occurrences in the Volga river basin and adjacent territories, located for the most part on the Russian plain of European Russia. The dataset is based on our own studies that were conducted in the years 1996-2020. The dataset consists of 5,030 incident records, all linked to geographical coordinates. A total of 13 amphibian species belonging to nine genera and six families have been registered within the studied territory, although the distribution of amphibian species in this region of Russia has not yet been fully studied. This is especially relevant with the spread of cryptic species that can only be identified using molecular genetic research methods. The main purpose of publishing a database is to make our data available in the global biodiversity system to a wide range of users. The data can be used by researchers, as well as helping the authorities to manage their territory more efficiently. All occurrences are published in GBIF for the first time. Most of the data are stored in field diaries and we would like to make it available to everyone by adding it in the global biodiversity database (GBIF).

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