Mass Aggregation Research Articles

Badenian (Middle Miocene) echinoids and starfish from western Ukraine, and their biogeographic and stratigraphic significance

Abstract Echinoderms from the Badenian (Middle Miocene) of the Fore-Carpathian Basin of western Ukraine are facies restricted. The Mykolaiv Beds, stratigraphically older, yielded the starfish Astropecten forbesi (complete skeletons), two genera of sand dollars (Parascutella, Parmulechinus), and numerous other echinoids of the genera Psammechinus , Echinocyamus, Spatangus, Hemipatagus, Echinocardium, Clypeaster, Echinolampas, and Conolampas. The stratigraphically younger, calcareous Ternopil Beds yielded Eucidaris (complete coronae, isolated spines), Arbacina , Brissus, and Rhabdobrissus. Sixteen species of echinoids are distinguished and/or commented. A new brissid, Rhabdobrissus tarnopolensis sp. nov., is established. A mass occurrence of some species (Psammechinus dubius and Hemipatagus ocellatus) contrasts with that of mass aggregations (sand dollars and Echinocardium leopolitanum) by dynamic events in selected layers of proximal tempestites. Of special note is the occurrence of very small specimens, interpreted as juveniles (‘babies’) having been swept out of their restricted biotopes (‘nurseries’). Some species hitherto regarded as of Early Miocene age, and the problem of their persistence beyond the Fore-Carpathian Basin and/or migration into that basin during the Middle Miocene transgression are discussed.

The growth of galactic bulges through mergers in Λ cold dark matter haloes revisited – II. Morphological mix evolution

The mass aggregation and merger histories of present-day distinct haloes selected from the cosmological Millennium Simulations I and II are mapped into stellar mass aggregation and galaxy merger histories of central galaxies by using empirical stellar-to-halo and stellar-to-gas mass relations. The growth of bulges driven by the galaxy mergers/interactions is calculated using dynamical prescriptions. The predicted bulge demographics at redshift z~0 is consistent with observations (Zavala+2012). Here we present the evolution of the morphological mix (traced by the bulge-to-total mass ratio, B/T) as a function of mass up to z=3. This mix remains qualitatively the same up to z~1: B/T<0.1 galaxies dominate at low masses, 0.1<B/T<0.45 at intermediate masses, and B/T>0.45 at large masses. At z>1, the fractions of disc-dominated and bulgeless galaxies increase strongly, and by z~2 the era of pure disc galaxies is reached. Bulge-dominated galaxies acquire such a morphology, and most of their mass, following a downsizing trend. Since our results are consistent with most of the recent observational studies of the morphological mix at different redshifts, a LCDM-based scenario of merger-driven bulge assembly does not seem to face critical issues. However, if the stellar-to-halo mass relation changes too little with redshift, then some tensions with observations appear.

Understanding dynamics of polysulfide dissolution and re-deposition in working lithium–sulfur battery by in-operando transmission X-ray microscopy

The dynamics of polysulfide (PS) dissolution and re-deposition during electrochemical charge/discharge of the lithium-sulfur (Li–S) cell has been investigated in a quantitative manner based on in-operando transmission X-ray microscopy (TXM) analysis of dimensional variations of S particles in working cells that have been subjected to different depths of charge/discharge. Extensive shrinkage and expansion of S particles have been observed to result from PS dissolution and re-deposition, respectively. The dissolution rate of PS is found to have complex dependence on the Li content, being significantly higher for the stoichiometries of LiS8 and Li2S4 than those between Li2S8 and Li2S6. PS re-deposition is nucleation-limited, leading to considerable aggregation of the S-containing active mass and enormous dimensional variations of active particles. These two consequences may impose threat to the cycle stability of the electrode. Possible benefit of introducing favorable nucleation sites is discussed.

Survival of brooding females and characteristics of oviposition sites ofUmbonia crassicornis(Amyot &amp; Serville, 1843) (Hemiptera: Membracidae)

Abstract The goals of this study were to 1) determine the field survival rate of single and multiple U. crassicornis females tending their offspring, 2) determine if a female will adopt an egg mass or nyphal aggregation that has lost its parental female as is seen in other treehoppers, 3)determine the physical characteristics of the sites selected by female U. crassicornis for oviposition and 4) show how these data interrelate and explain the pattern of U. crassicornis egg mass deposition within and among the host plants. An average of 27.9% of the female U. crassicornis survived until their offspring reached maturity. Having two or more females at a site doubles the probability of at least one surviving until the offspring reach maturity. An egg mass or nymphal aggregation without a guarding female may be adopted by another female. Females need four to seven cm of plant tissue 2.5 to 3.5 mm in diameter that they can encircle with their mesothoracic legs in which to oviposit. The females do not aggregate ...

Power in the Reverberation

This Twitter Research Forum essay by Communication &amp; Sport Associate Editor Andrew Billings explores the problems underlying research efforts reliant on the mass aggregation of tweets within the social media platform. It is argued that Twitter research can often overlook the staying power of sport on television while overestimating the adoption and use of Twitter in the sporting context. Assertions about Twitter’s role in democratizing sport need to be tested carefully as does the dynamic of Twitter’s role in setting the mainstream sport media agenda. A key argument is made that Twitter is worth studying in the realm of sports media not because it is a great representation of the overall public but precisely because it is not at all representative of any generalized population, most certainly including the far-from-monolithic sports fan.

Self-similarity in Smoluchowski’s Coagulation Equation

Smoluchowski’s coagulation equation is one of the fundamental deterministic models that describe mass aggregation phenomena. A key question in the analysis of this equation is whether the large-time behaviour of solutions is universal and described by special self-similar solutions. This issue is however only well-understood for the small class of solvable kernels while the analysis for non-solvable kernels still poses many challenging problems.

Preface Issue 1-2014

Last year, the Zentralblatt fur Mathematik and the Jahresbericht der DMV began a collaboration to review again classical books and papers and the effect that they have had or could have had on the development of specific mathematical branches from today’s point of view. It has turned out that these renewed reviews build a category of articles of its own and that they cannot in general be considered as book reviews or historical articles. For this reason we introduce the new category “Classics Revisited” and shall try to have one article of this kind in each issue. We begin with a new review by Jean-Pierre Otal of William Thurston’s 1982 paper on “Three-dimensional manifolds, Kleinian groups and hyperbolic geometry”. This research announcement did not only contain his Geometrization Conjecture and his Hyperbolization Theorem for so called Haken manifolds but also a list of 24 of at that time open problems, of which 22 had been solved by 2012. Only few papers have been of such a strong influence and inspiration. Bosons are particles in quantum mechanics which do not obey the Pauli principle. If a large fraction of particles in a Bose fluid occupies the same quantum state, the so called Bose-Einstein condensation occurs and leads to physically remarkable phenomena like superfluidity. This means that the viscosity of a fluid vanishes completely at low temperatures. Robert Seiringer’s survey article on “The excitation spectrum for Bose fluids with weak interaction” reviews recent progress in understanding underlying mathematical models. Mass aggregation phenomena like e.g. polymerisation may be modelled by means of Smoluchowski’s coagulation equation. Barbara Niethammer’s survey article addresses the key question in understanding the large time behaviour of solutions

Hollow-fiber flow field-flow fractionation with multi-angle laser scattering detection for aggregation studies of therapeutic proteins

The rapid development of protein-based pharmaceuticals highlights the need for robust analytical methods to ensure their quality and stability. Among proteins used in pharmaceutical applications, an important and ever increasing role is represented by monoclonal antibodies and large proteins, which are often modified to enhance their activity or stability when used as drugs. The bioactivity and the stability of those proteins are closely related to the maintenance of their complex structure, which however are influenced by many external factors that can cause degradation and/or aggregation. The presence of aggregates in these drugs could reduce their bioactivity and bioavailability, and induce immunogenicity. The choice of the proper analytical method for the analysis of aggregates is fundamental to understand their (size) dimensional range, their amount, and if they are present in the sample as generated by an aggregation or as an artifact due to the method itself. Size exclusion chromatography is one of the most important techniques for the quality control of pharmaceutical proteins; however, its application is limited to relatively low molar mass aggregates. Among the techniques for the size characterization of proteins, field-flow fractionation (FFF) represents a competitive choice because of its soft mechanism due to the absence of a stationary phase and application in a broader size range, from nanometer- to micrometer-sized analytes. In this paper, the microcolumn variant of FFF, the hollow-fiber flow FFF, was online coupled with multi-angle light scattering, and a method for the characterization of aggregates with high reproducibility and low limit of detection was demonstrated employing an avidin derivate as sample model.

Analytical Study of Giant Fluctuations and Temporal Intermittency

We study analytically giant fluctuations and temporal intermittency in a stochastic one-dimensional model with diffusion and aggregation of masses in the bulk, along with influx of single particles and outflux of aggregates at the boundaries. We calculate various static and dynamical properties of the total mass in the system for both biased and unbiased movement of particles and different boundary conditions. These calculations show that (i) in the unbiased case, the total mass has a non-Gaussian distribution and shows giant fluctuations which scale as system size (ii) in all the cases, the system shows strong intermittency in time, which is manifested in the anomalous scaling of the dynamical structure functions of the total mass. The results are derived by taking a continuum limit in space and agree well with numerical simulations performed on the discrete lattice. The analytic results obtained here are typical of the full phase of a more general model with fragmentation, which was studied earlier using numerical simulations.

Harmonia axyridis (Coleoptera: Coccinellidae) as a host of the parasitic fungus Hesperomyces virescens (Ascomycota: Laboulbeniales, Laboulbeniaceae): A case report and short review

Hesperomyces virescens is an ectoparasite of some Coccinellidae, which until the mid-1990s was relatively rarely only reported from warm regions in various parts of the world. Analysis of the host and distribution data of H. virescens recorded in the Western Palaearctic and North America reveals several trends in the occurrence and abundance of H. virescens: (1) it has recently been much more frequently recorded, (2) most of the recent records are for more northerly (colder) localities than the early records and (3) the recent records are mostly of a novel host, the invasive harlequin ladybird (Harmonia axyridis). While in North America H. virescens is almost exclusively found on H. axyridis, all European records of this association are very recent and still less numerous than records of Adalia bipunctata as a host. However, based on a relatively few published cases of the H. axyridis-H. virescens association in Europe and the case described in this paper, it is clear that the harlequin ladybird is currently the main host of this parasite. These changes in the abundance and geographical distribution of H. virescens are probably linked to some features of H. axyridis, such as its abundance, multivoltinism with overlapping generations, high level of promiscuity and overwintering in mass aggregations. The occurrence of these features in one species may make it especially suitable for H. virescens and other parasites that require close contact of host individuals for efficient transmission. Indeed, some of the data indicate that parasites other than H. virescens, like the podapolipid mite Coccipolipus hippodamiae and allantonematid nematodes of the genus Parasitylenchus may also heavily parasitize H. axyridis. We hypothesize that the acquisition of H. axyridis as a host by H. virescens, C. hippodamiae and Parasitylenchus spp. may have further consequences for the abundance and distribution of these parasites, including the expansion of their ranges to other continents colonized by invasive populations of this ladybird and areas in Asia where H. axyridis is native.

Surveillance in ubiquitous network societies: normative conflicts related to the consumer in-store supermarket experience in the context of the Internet of Things

The Internet of Things (IoT) is an emerging global infrastructure that employs wireless sensors to collect, store, and exchange data. Increasingly, applications for marketing and advertising have been articulated as a means to enhance the consumer shopping experience, in addition to improving efficiency. However, privacy advocates have challenged the mass aggregation of personally-identifiable information in databases and geotracking, the use of location-based services to identify one's precise location over time. This paper employs the framework of contextual integrity related to privacy developed by Nissenbaum (Privacy in context: technology, policy, and the integrity of social life. Stanford University Press, Stanford, 2010) as a tool to understand citizen response to implementation IoT-related technology in the supermarket. The purpose of the study was to identify and understand specific changes in information practices brought about by the IoT that may be perceived as privacy violations. Citizens were interviewed, read a scenario of near-term IoT implementation, and were asked to reflect on changes in the key actors involved, information attributes, and principles of transmission. Areas where new practices may occur with the IoT were then highlighted as potential problems (privacy violations). Issues identified included the mining of medical data, invasive targeted advertising, and loss of autonomy through marketing profiles or personal affect monitoring. While there were numerous aspects deemed desirable by the participants, some developments appeared to tip the balance between consumer benefit and corporate gain. This surveillance power creates an imbalance between the consumer and the corporation that may also impact individual autonomy. The ethical dimensions of this problem are discussed.

Yet another polymorph of α-synuclein: solid-state sequential assignments

Parkinson's disease is a neurological human proteinopathy, which is caused by the accumulation of protein aggregates of high molecular mass. α-Synuclein is a major component of these fibrillar, β-sheet rich, insoluble assemblies and is deposited in the form of amyloids. Structural characterization of amyloids is possible by solid-state NMR, although no atomic-resolution structure is available as of today. α-Synuclein, as many other pathology-related fibril-forming proteins, can form a number of different polymorphs that are sometimes tricky to obtain in pure form. Here, we describe the chemical shifts and secondary structure analysis of a polymorph that also adopts mainly β-sheet conformation, with a fibrillar core ranging from residues 38 to 94. In addition, residues 15-20 from the N-terminus found to be part of a rigid ordered β-sheet. The chemical shifts differ substantially from the polymorph we previously assigned.

The growth in size and mass of cluster galaxies since z = 2

We study the formation and evolution of Brightest Cluster Galaxies starting from a $z=2$ population of quiescent ellipticals and following them to $z=0$. To this end, we use a suite of nine high-resolution dark matter-only simulations of galaxy clusters in a $\Lambda$CDM universe. We develop a scheme in which simulation particles are weighted to generate realistic and dynamically stable stellar density profiles at $z=2$. Our initial conditions assign a stellar mass to every identified dark halo as expected from abundance matching; assuming there exists a one-to-one relation between the visible properties of galaxies and their host haloes. We set the sizes of the luminous components according to the observed relations for $z\sim2$ massive quiescent galaxies. We study the evolution of the mass-size relation, the fate of satellite galaxies and the mass aggregation of the cluster central. From $z=2$, these galaxies grow on average in size by a factor 5 to 10 of and in mass by 2 to 3. The stellar mass growth rate of the simulated BCGs in our sample is of 1.9 in the range $0.3<z<1.0$ consistent with observations, and of 1.5 in the range $0.0<z<0.3$. Furthermore the satellite galaxies evolve to the present day mass-size relation by $z=0$. Assuming passively evolving stellar populations, we present surface brightness profiles for our cluster centrals which resemble those observed for the cDs in similar mass clusters both at $z=0$ and at $z=1$. This demonstrates that the $\Lambda$CDM cosmology does indeed predict minor and major mergers to occur in galaxy clusters with the frequency and mass ratio distribution required to explain the observed growth in size of passive galaxies since $z=2$. Our experiment shows that Brightest Cluster Galaxies can form through dissipationless mergers of quiescent massive $z=2$ galaxies, without substantial additional star formation.

Mass function and assembly of dark haloes: an approach to inventory isolated overdense regions in random fields

In order to attain a statistical description of the evolution of cosmic density fluctuations in agreement with results from the numerical simulations, we introduce a probability conditional formalism (CF) based on an inventory of isolated overdense regions in a density random field. This formalism is a useful tool for describing at the same time the mass function (MF) of dark haloes, their mass aggregation histories (MAHs) and merging rates (MRs). The CF focuses on virialized regions in a self-consistent way rather than in mass elements, and it offers an economical description for a variety of random fields. Within the framework of the CF, we confirm that, for a Gaussian field, it is not possible to reproduce at the same time the MF, MAH, and MR of haloes, both for a constant and moving barrier. Then, we develop an inductive method for constraining the cumulative conditional probability from a given halo MF description, and thus, using the CF, we calculate the halo MAHs and MRs. By applying this method to the MF measured in numerical simulations by Tinker et al. 2008, we find that a reasonable solution, justified by a mass conservation argument, is obtained if ones introduce a rescaling -increment by ~30% - of the virial mass used in simulations and a (slight) deviation from Gaussianity. Thus, both the MAH and MR obtained by a Monte Carlo merger tree agree now with the predictions of numerical simulations. We discuss on the necessity of rescaling the virial mass in simulations when comparing with analytical approaches on the ground of the matter not accounted as part of the halos and the halo mass limit due to numerical. Our analysis supports the presence of a diffuse dark matter component that is not taken into account in the measured halo MFs inasmuch as it is not part of the collapsed structures.

Behavior of Natural Fiber in Stone Matrix Asphalt Mixtures Using Two Design Methods

AbstractThe technology of asphalt materials and mixtures has evolved in the last four decades in Europe and North America. For the surface layer, there has been an increase in the use of more resistant and durable asphalt mixtures, such as mixtures with discontinuous graduation, e.g., stone matrix asphalt (SMA),which is a gap graded mixture containing 70–80% coarse aggregate of total aggregate mass, 6–7% of binder, 8–12% of filler, and about 0.3–0.5% of fiber. The fibers hold the binder in the mixture at high temperature and prevent drainage during production, transportation, and construction. This research presents a study of the behavior of natural fibers (coconut and cellulose fibers) on SMA mixtures using two different design methods (Marshall and Superpave). The specimens were tested using several common laboratory test procedures: draindown test, indirect tensile strength, resilient modulus, fatigue life, and moisture susceptibility. The draindown test results clearly revealed that coconut fiber can...

A paradoxidid moult ensemble from the Cambrian of Sweden

A mass aggregation of 148 paradoxidid trilobites and associated specimens of the agnostoid Pentagnostus praecurrens is preserved on a surface of a split orsten lens from the Middle Cambrian Series 3 Acadoparadoxides pinus–P. praecurrens Zone in Jämtland, Sweden. Most specimens are complete or nearly complete, lying parallel to the sediment surface and seem unaffected by currents or sorting. The association is interpreted as a moult ensemble. Paradoxidid specimens are represented by two taxa, identified as paradoxidid sp. 1 (n = 28 specimens) and Eccaparadoxides sp. 2 (n = 45 specimens). The species are preserved both dorsum up and dorsum down, in about equal number, which may reflect a natural tendency to moult in either posture. They probably moulted by opening the cephalic sutures along the wide rostrum. The dorsal sutures are invariably open and the librigenae are very often displaced, commonly backwards in relation to the cranidium, but not symmetrically in relation to the axial shield. The glabella of the paradoxidids is often crushed, so that sometimes the underlying hypostome is outlined. Very few examples show the joint between the cranidium and the trunk being broken. Facies interpretation suggests deposition below storm wave base. Rapid burial, possibly by blanketing from hypopycnal flows followed by an extended period of slow sediment input (Type 1 facies of Brett et al. 2012) may explain the unusual preservation. The animals may have lived in an ex-aerobic environment, but evidence to support this is at the moment insubstantial.

A TWO-PHASE SCENARIO FOR BULGE ASSEMBLY IN ΛCDM COSMOLOGIES

We analyze and compare the bulges of a sample of L* spiral galaxies in hydrodynamical simulations in a cosmological context, using two different codes, P-DEVA and GASOLINE. The codes regulate star formation in very different ways, with P-DEVA simulations inputing low star formation efficiency under the assumption that feedback occurs on subgrid scales, while the GASOLINE simulations have feedback which drives large scale outflows. In all cases, the marked knee-shape in mass aggregation tracks, corresponding to the transition from an early phase of rapid mass assembly to a later slower one, separates the properties of two populations within the simulated bulges. The bulges analyzed show an important early starburst resulting from the collapse-like fast phase of mass assembly, followed by a second phase with lower star formation, driven by a variety of processes such as disk instabilities and/or mergers. Classifying bulge stellar particles identified at z=0 into old and young according to these two phases, we found bulge stellar sub-populations with distinct kinematics, shapes, stellar ages and metal contents. The young components are more oblate, generally smaller, more rotationally supported, with higher metallicity and less alpha-element enhanced than the old ones. These results are consistent with the current observational status of bulges, and provide an explanation for some apparently paradoxical observations, such as bulge rejuvenation and metal-content gradients observed. Our results suggest that bulges of L* galaxies will generically have two bulge populations which can be likened to classical and pseudo-bulges, with differences being in the relative proportions of the two, which may vary due to galaxy mass and specific mass accretion and merger histories.

Multiple peak aggregations for the Keller–Segel system

In this paper we derive matched asymptotic expansions for a solution of the Keller–Segel system in two space dimensions for which the amount of mass aggregation is 8πN, where N = 1, 2, 3, … Previously available asymptotics had been computed only for the case in which N = 1.

Characterization and Preliminary Toxicity Assay of Nano‐Titanium Dioxide Additive in Sugar‐Coated Chewing Gum

Nanotechnology shows great potential for producing food with higher quality and better taste through including new additives, improving nutrient delivery, and using better packaging. However, lack of investigations on safety issues of nanofood has resulted in public fears. How to characterize engineered nanomaterials in food and assess the toxicity and health impact of nanofood remains a big challenge. Herein, a facile and highly reliable separation method of TiO2 particles from food products (focusing on sugar-coated chewing gum) is reported, and the first comprehensive characterization study on food nanoparticles by multiple qualitative and quantitative methods is provided. The detailed information on nanoparticles in gum includes chemical composition, morphology, size distribution, crystalline phase, particle and mass concentration, surface charge, and aggregation state. Surprisingly, the results show that the number of food products containing nano-TiO2 (<200 nm) is much larger than known, and consumers have already often been exposed to engineered nanoparticles in daily life. Over 93% of TiO2 in gum is nano-TiO2 , and it is unexpectedly easy to come out and be swallowed by a person who chews gum. Preliminary cytotoxicity assays show that the gum nano-TiO2 particles are relatively safe for gastrointestinal cells within 24 h even at a concentration of 200 μg mL(-1) . This comprehensive study demonstrates accurate physicochemical property, exposure, and cytotoxicity information on engineered nanoparticles in food, which is a prerequisite for the successful safety assessment of nanofood products.

Concrete produced with recycled aggregates

This paper presents the analysis of the mechanical and durable properties of recycled aggregate concrete (RAC) for using in concrete. The porosity of recycled coarse aggregates is known to influence the fresh and hardened concrete properties and these properties are related to the specific mass of the recycled coarse aggregates, which directly influences the mechanical properties of the concrete. The recycled aggregates were obtained from construction and demolition wastes (CDW), which were divided into recycled sand (fine) and coarse aggregates. Besides this, a recycled coarse aggregate of a specific mass with a greater density was obtained by mixing the recycled aggregates of the CDW with the recycled aggregates of concrete wastes (CW). The concrete was produced in laboratory by combining three water-cement ratios, the ratios were used in agreement with NBR 6118 for structural concretes, with each recycled coarse aggregates and recycled sand or river sand, and the reference concrete was produced with natural aggregates. It was observed that recycled aggregates can be used in concrete with properties for structural concrete. In general, the use of recycled coarse aggregate in combination with recycled sand did not provide good results; but when the less porous was used, or the recycled coarse aggregate of a specific mass with a greater density, the properties of the concrete showed better results. Some RAC reached bigger strengths than the reference concrete.