Primitive Characteristics Research Articles

Effects of RPL objective functions on the primitive characteristics of mobile and static IoT infrastructures

The emergence of mobile IoT applications in recent years and the challenge of routing in their infrastructures have motivated scholars to propose appropriate routing mechanisms for such systems. Meanwhile, the IPv6 Routing Protocol for Low Power and Lossy Networks (RPL) is the standard routing protocol for IoT infrastructures. Nevertheless, RPL was mainly designed to comply with the primitive requirements of static IoT applications and it behaves poorly in confronting with the severe alterations in mobile conditions. The most important factor for such a poor behavior in mobile applications is the inappropriate design of OFs, which determine RPL’s routing policies in the network. Therefore, the functionality and efficiency of the existing OFs should be carefully studied in order to determine their downsides and to resolve them in the future OF designs. Accordingly, in this paper, due to lack of information on how OFs affect the primary requirements of IoT infrastructures in mobile and static infrastructures, we have compared and evaluated the effect of state of the art OFs on the functionality of the nodes and the network from different perspectives. Our evaluations on fixed-node IoT infrastructures have shown that OFs could affect the power consumption by up to 80%, while their impact on reliability and E2E delay would be as high as 54% and 75%, respectively. Further observations have proven that mobility would reduce OFs contribution in power consumption by more than 10% in comparison with static IoT infrastructures, while it can increase their influence on reliability and E2E delay by nearly 15% and 16%, respectively.

A cometary building block in a primitive asteroidal meteorite

Meteorites originating from primitive C-type asteroids are composed of materials from the Sun’s protoplanetary disk, including up to a few per cent organic carbon. In contrast, some interplanetary dust particles and micrometeorites have much higher carbon contents, up to >90%, and are thought to originate from icy outer Solar System bodies and comets. Here we report an approximately 100-µm-diameter very carbon-rich clast, with highly primitive characteristics, in the matrix of a CR2 chondrite, LaPaz Icefield 02342. The clast may represent a cometary building block, largely unsampled in meteorite collections, that was captured by a C-type asteroid during the early stages of planet formation. The existence of this cometary microxenolith supports the idea of a radially inward transport of materials from the outer protoplanetary disk into the CR chondrite reservoir during the formation of planetesimals. Moreover, the H-isotopic composition of the clast is suggestive of a temporal evolution of organic isotopic compositions in the comet-forming region of the disk. The composition and characteristics of a C-rich clast within the LaPaz Icefield 02342 meteorite suggests that the clast is composed of materials related to comets and icy bodies. The clast probably formed in the outer Solar System, was transported inward and finally accreted into LaPaz’s parent body.

Origin of the Vanadiferous Serpentine–Magnetite Rocks of the Mt. Sorcerer Area, Lac Doré Layered Intrusion, Chibougamau, Québec

Magmatic processes dominate Fe–Ti–V mineralization and revealing these processes is essential for providing a scientific foundation for exploration models. This study focuses on the metamorphosed Neoarchean (ca. 2728 Ma) tholeiitic layered Lac Doré Complex (LDC) that is currently being explored for V. Contamination may play an important role in the evolution of the Fe–Ti–V-enriched layered zone (magnetitite, anorthosite, and gabbro mostly, and ultramafic rocks locally) of the LDC. This hypothesis is tested by performing a detailed chemical and petrological investigation of serpentine-magnetite-dominated rocks located in the Mt. Sorcerer area. The studied rocks have evolved (apatite-bearing, Fe-rich, Cr-Ni-Ti-poor) and primitive (Mg-rich, Si-poor) characteristics. Pre-metamorphism rocks contained olivine Fo82–90 (now serpentine) and magnetite. These rocks formed from a Si-depleted magma under high fO2 conditions (+1.8 to +3.0 relative to the fayalite-magnetite-quartz buffer; FMQ). The V-content of the magnetite varies due to reversals related to multiple injections of an evolved basaltic magma in the upper part of the LDC. The magma interacted with Fe-Mg-rich and Si-Ca-poor carbonate-facies iron formation and crystallized in the presence of oxidizing CO2-bearing fluids. Compositional layering is poorly defined due to a fast cooling rate. Consequently, the distribution of V is relatively homogeneous in the Fe–Mg-rich units of the Mt. Sorcerer area.

NNBench-X: Benchmarking and Understanding Neural Network Workloads for Accelerator Designs

The tremendous impact of deep learning algorithms over a wide range of application domains has encouraged a surge of neural network (NN) accelerator research. An evolving benchmark suite and its associated benchmark method are needed to incorporate emerging NN models and characterize NN workloads. In this paper, we propose a novel approach to understand the performance characteristic of NN workloads for accelerator designs. Our approach takes as input an application candidate pool and conducts an operator-level analysis and application-level analysis to understand the performance characteristics of both basic tensor primitives and whole applications. We conduct a case study on the TensorFlow model zoo by using this proposed characterization method. We find that tensor operators with the same functionality can have very different performance characteristics under different input sizes, while operators with different functionality can have similar characteristics. Additionally, we observe that without operator-level analysis, the application bottleneck is mischaracterized for 15 out of 57 models from the TensorFlow model zoo. Overall, our characterization method helps users select representative applications out of the large pool of possible applications, while providing insightful guidelines for the design of NN accelerators.

КОМПОЗИЦІЯ ЯК ЧИННИК ХУДОЖНЬОЇ ВИРАЗНОСТІ ТВОРІВ ГРАФІЧНОГО ДИЗАЙНУ

Мета – дослідити вплив композиції на змістове наповнення й декодування візуальних повідомлень. Методологія дослідження - в досліджені впроваджені метод теоретичного та структурно-семіотичного аналізу. Завдяки схематизації інформаційно-змістових елементів доведено вплив композиції на швидкість та точність декодування інформації; висвітлено залежність декодування змісту від різних способів композиційної організації. Наукова новизна полягає у виявленні залежності змістового декодування відносно нейтральних комунікативних елементів від способів їх композиційної організації та у виявленні ролі композиції в формуванні візуально-стилістичної єдності носіїв фірмового стилю. Встановлено, що спосіб кодування інформації на основі асоціативного варіювання властивостями геометричних примітивів, або наближених до них форм призводить до формування логіки сприйняття знаків – образологіки, що дозволяє співвідносити схематизовані площинні зображення з об’єктами, процесами та явищами навколишнього світу. Закономірності такої образологіки співвіднесено з принципами гештальду, сформованими в психологічній галузі. Висновки. Зміст візуальних повідомлень сприймається як відповідність цілісності образної побудови інформаційної структури до сутності візуально кодованих зображень. Також постає значущість композиційної структури як цілісності, здатної набувати синергічних ознак й передавати інформацію значно більшу, ніж сукупність окремо взятих елементів. Дієвість механізмів «переробки» значної кількості образного, змістового та емоційного матеріалу в набор стереотипних уявлень, що активно продукуються і споживаються масовою культурою, забезпечується завдяки схематизації і дотримання умов композиційного представлення інформаційних кодів, дієвість впливу яких є подібною до творів образотворчого мистецтва. Утримання принципів композиційної організації інформації, висвітлених у даній публікації, забезпечує єднання ідеї та форм її графічного втілення.

Mantle source heterogeneity in subduction zones: constraints from elemental and isotope (Sr, Nd, and Pb) data on Vulcano Island, Aeolian Archipelago, Italy

Vulcano is part of the Aeolian volcanic arc in the southern Tyrrhenian Sea. Its products were emplaced through multiple episodes of edifice building and collapse since about 120 ka B.P. to present. A major discontinuity in the activity occurred after about 28 ka, while the focus of volcanism moved from SE to NW. The older products are basalts to shoshonites, and have lower K2O than the younger ones, shoshonites to rhyolites. Between these two groups, Lentia latites-rhyolites, Spiaggia Lunga basalts, and Quadrara shoshonite-trachytes, erupted along the western side of Vulcano Island. The Spiaggia Lunga basalts (i) are the most primitive magmas erupted at Vulcano after 28 ka (ii) mark the change between older and younger phases, and (iii) overlap geochemically with a monzogabbroic intrusion of similar age. This work focuses on the Spiaggia Lunga products, discussed within a large dataset of geochemical and radiogenic isotope analyses on the entire Vulcano sequence. Older products have more primitive geochemical and isotope characteristics, and lower incompatible element contents, than younger ones. The Spiaggia Lunga basalts exhibit intermediate geochemical characteristics between the older and the younger groups, and can likely be regarded as a third magmatic phase, which represents a distinct mantle reservoir active during the magmatic history of Vulcano. Significant variations of Sr, Nd, and Pb isotope ratios, and isotopic disequilibrium between phenocrysts and groundmass, are present among the Vulcano products. This variability suggests crustal assimilation in shallow-level magma chambers, which also accounts for the formation of evolved products by combined assimilation and fractional crystallization, particularly in the younger series. Considering only the mafic products, incompatible element patterns with high LILE/HFSE and enriched signatures of Sr, Nd, and Pb isotope ratios, indicate enriched mantle sources. Besides, chemical and isotope variability among older, younger, and Spiaggia Lunga mafic rocks, suggests an origin from geochemically diverse primary melts, derived from distinct mantle reservoirs. Their parent magmas, based on geochemical and isotope patterns, were from both MORB- and OIB-type mantle sources, subject to variable degrees of metasomatism by subducted sediments.

Mustelids (Carnivora, Mammalia) from Monte Tuttavista fissure fillings (Early and Middle Pleistocene; Orosei, Sardinia): Taxonomy and evolution of the insular Sardinian Galictini

The insular environment of Sardinia is renowned for its extensive palaeontological Palaeogene record, extending from the Eocene until recent times. In Sardinia, one of the most important localities for Quaternary faunas is the fillings of the karst fissures of the Monte Tuttavista site complex, which contain an impressive amount of fossil remains of around 70 vertebrate taxa. Several studies that have examined the network of the karst fissure cavities and their fossils have revealed some issues regarding the biochronological ordering, as well as some peculiarities in the recovered faunal associations (such as the presence of several carnivores). In this study, we analysed the record of the two large mustelids from this site, the genera Pannonictis and Enhydrictis. Our analyses point out several singular morphological and morphometric features of these taxa that suggest their attribution to two new species, Pannonictis baroniensis nov. sp. and Enhydrictis praegalictoides nov. sp. The proportions and the robust morphologies of P. baroniensis resemble those of other European taxa, such as P. pliocaenica, although other dentognatic and cranial features exclude a conspecific identity with previously known taxa. Conversely, E. praegalictoides represents the earliest member of the genus and shows a mixed pattern of derived features that are shared with the peculiar E. galictoides recovered from other Middle-Late Pleistocene Sardinian localities, as well as other more primitive characteristics that do not occur in this endemic mustelid. Considering the controversial debate regarding the evolutionary history of the tribe Galictini, the record of these new endemic species expands our knowledge of the systematics and the biogeography of the galictines and enriches the diversity of the tribe during the Early and Middle Pleistocene.

Phylogenetic and morphological analysis of a new cliff-dwelling species reveals a remnant ancestral diversity and evolutionary parallelism in Sonchus (Asteraceae)

We describe a new cliff-dwelling species within Sonchus (Asteraceae): Sonchus boulosii and analyze its systematic position and evolutionary significance; in addition, we provide a key to the species of Sonchus in Morocco. Both morphological and ecological characteristics suggest a close relationship of S. boulosii with taxa of section Pustulati. However, ITS nrDNA and cpDNA matK markers indicate its uncertain position within the genus, but clear genetic differentiation from the remaining major clades. ITS phylogenetic trees show that likely evolutionary shifts to rocky habitat took place at least five times within genus Sonchus and that sect. Pustulati and S. boulosii clades have a clearly independent evolutionary origin. We postulate that the strong resemblance of S. boulosii to other rocky species reflects a phenomenon of homoplasy, probably driven by parallel evolutionary adaptations to the severe ecological constraints of its cliff face habitat. Therefore, a new section is also described, which includes S. boulosii as its sole representative: section Pulvinati. According to phylogenetic trees, the new clade may share its common ancestor with the clade comprising sections Maritimi and Arvenses, from which it is widely divergent in morphology and ecology, with the exception of Sonchus novae-zelandiae. However, the latter is a derived taxon, with high level of polyploidy unlike S. boulosii that shows 2n = 18, basal chromosome number of the genus. Since sections Pulvinati and Pustulati seem to be quite old in Sonchus, we also hypothesize that some similarities, such as fruit morphology, may reflect the persistence of some primitive characteristics.

A new species of Masteria L. Koch, 1873 (Dipluridae: Masteriinae) from Guyana.

Mygalomorphs are a diverse spider group with primitive characteristics composed of the largest spider species in the world, however some species may be very small (Bond et al. 2012; Rogerio et al. 2013). The small spiders of the subfamily Masteriinae (Dipluridae, Mygalomorphae) can be found in Asia and South America (Raven 1981; Pedroso et al. 2015; WSC 2017). The subfamily is represented by two genera: Masteria L. Koch, 1873 and Striamea Raven, 1981. Masteria species can be identified by the following combination of characters: absence of cuspules in endites and labium; zero, two, six or eight eyes; and with or without paraembolic apophysis on the male palpal bulb (Raven 1981, 1985, 1991; Alayón 1995; Bertani et al. 2013; Pedroso et al. 2015). Currently, 24 species of Masteria are described, with 6 species found in South America: Masteria colombiensis, Raven, 1981 from Colombia; M. manauara Bertani, Cruz Oliveira 2013 and M. emboaba Pedroso, Baptista Bertani, 2015 from Brazil; M. cyclops (Simon 1889), M. tovarensis (Simon, 1889) and M. lucifuga (Simon, 1889) from Venezuela (WSC 2017). We document herein the first record and description of a new species of the genus Masteria from Guyana.

Web Service Interaction Modeling and Verification Using Recursive Composition Algebra

The design principle of composability among Web services is one of the most crucial reasons for the success and popularity of Web services. However, achieving error-free automatic Web service composition is still a challenge. In this paper, we propose a recursive composition based modeling and verification technique for Web service interaction. The application of recursive composition over a Web service with respect to a given set of Web services yields a recursive composition interaction graph (RCIG). In order to capture the requirement specifications of a Web service interaction scenario, we propose recursive composition specification language (RCSL) as a requirement specification language. Further, we employ the proposed RCIG as an interpretation model to interpret the semantics of a RCSL formula. Our verification technique is based on the generation and analysis of all possible interaction patterns. Performance evaluation results, provided in this paper, show that our proposition is implementable for the real world applications. The key advantages of the proposed approach are: (i) it does not require explicit system modeling as in model checking based approaches, (ii) it captures primitive characteristics of Web service interaction patterns, such as recursive composition, sequential and parallel flow, etc, and (iii) it supports automatic composition of services.

Discovery of a long-term refuge for ostracods (Crustacea) after the end-Permian extinction: a unique Carnian (Late Triassic) fauna from the Mersin Mélange, southern Turkey

The Mersin Mélange, located in southern Turkey north-west of the city of Mersin, includes blocks and tectonic slices of different origins. The Kilek section in the Mersin Mélange was sampled for a thorough examination of its lithology, biostratigraphy and fossil content. Two samples from the cherty limestone layers within the Huglu Tuffites at the top of the section yielded a rich silicified ostracod fauna of late Early Carnian (based on a two-fold Carnian subdivision) or middle Middle Carnian age (based on a three-fold Carnian subdivision), deposited in an open marine environment, in the outer platform-upper slope zone. We report 121 ostracod species belonging to 53 genera. Two new genera are described: Edithobairdia Forel gen. nov. and Gencella Forel gen. nov., as well as 16 new species: Acanthoscapha mersinella Forel sp. nov., Bairdia hugluensis Forel sp. nov., Acratia kollmanni Forel sp. nov., Citrella? carniana Forel sp. nov., Cytheropteron? schornikovi Forel sp. nov., Eucytherura lacerata Forel sp. nov., Gencella taurensis Forel sp. nov., Kerocythere dorsidenticulata Forel sp. nov., Kerocythere tricostata Forel sp. nov., Monoceratina praevulsaformis Forel sp. nov., Patellacythere tourkosella Forel sp. nov., Polycope kilekensis Forel sp. nov., Ptychobairdia praekristanae Forel sp. nov., Simeonella daginikella Forel sp. nov., Spinomicrocheilinella reliquiaella Forel sp. nov. and Triassocythere tavuscayiriensis Forel sp. nov. The diagnosis of Acratia goemoeryi Kozur is emended. The Kilek fauna retains primitive characteristics illustrated by the first known occurrence of Palaeocopida and Rectonariidae (typical Palaeozoic forms) in the Late Triassic, associated with typical Triassic–modern elements such as thick-shelled and ornamented Bairdiidae and diverse Cytheroidea known from the Middle and Late Triassic worldwide. The unique composition of Palaeozoic and Mesozoic taxa from the Kilek section illustrates unexpected long-term survival in a deep-sea refuge zone following the end-Permian extinction, and the diachronous character of the ostracod recovery in different environments.http://zoobank.org/urn:lsid:zoobank.org.pub:662C3D5C–2B86–4D7B–BDB5–8F8B6A1AD1E7

Evolutionary origin of type IV classical cadherins in arthropods

BackgroundClassical cadherins are a metazoan-specific family of homophilic cell-cell adhesion molecules that regulate morphogenesis. Type I and type IV cadherins in this family function at adherens junctions in the major epithelial tissues of vertebrates and insects, respectively, but they have distinct, relatively simple domain organizations that are thought to have evolved by independent reductive changes from an ancestral type III cadherin, which is larger than derived paralogs and has a complicated domain organization. Although both type III and type IV cadherins have been identified in hexapods and branchiopods, the process by which the type IV cadherin evolved is still largely unclear.ResultsThrough an analysis of arthropod genome sequences, we found that the only classical cadherin encoded in chelicerate genomes was the type III cadherin and that the two type III cadherin genes found in the spider Parasteatoda tepidariorum genome exhibited a complex yet ancestral exon-intron organization in arthropods. Genomic and transcriptomic data from branchiopod, copepod, isopod, amphipod, and decapod crustaceans led us to redefine the type IV cadherin category, which we separated into type IVa and type IVb, which displayed a similar domain organization, except type IVb cadherins have a larger number of extracellular cadherin (EC) domains than do type IVa cadherins (nine versus seven). We also showed that type IVa cadherin genes occurred in the hexapod, branchiopod, and copepod genomes whereas only type IVb cadherin genes were present in malacostracans. Furthermore, comparative characterization of the type IVb cadherins suggested that the presence of two extra EC domains in their N-terminal regions represented primitive characteristics. In addition, we identified an evolutionary loss of two highly conserved cysteine residues among the type IVa cadherins of insects.ConclusionsWe provide a genomic perspective of the evolution of classical cadherins among bilaterians, with a focus on the Arthropoda, and suggest that following the divergence of early arthropods, the precursor of the insect type IV cadherin evolved through stepwise reductive changes from the ancestral type III state. In addition, the complementary distributions of polarized genomic characters related to type IVa/IVb cadherins may have implications for our interpretations of pancrustacean phylogeny.

Los cíclidos (Pisces: Pereiformes) de la Laguna de Términos y sus afluentes

Of the 283 cichlids collected between 1970 and 1973 in and around Laguna de Terminos, Campeche, Mexico, nine species (25% of the total cichlid fauna of Mcxico) have presently been identified. Identification is based on meristic and morphologic characteristics and on color patterns. The hydrologic basin of the Rio Usumacinta is one of the richest in cichlid populations which retain the primitive characteristics of tbe family: Petenia splendida, Cichlasoma meeki, C. aurcum, and C. pearsei. Cichlasoma fenestratum is curyhaline but restricted to tbe rivers and streams. On the other hand, C. urophthalmus appears to be better adapted to the marine conditions wbich occur along the coast of the Isla del Carmen Lagoon. It is also found athough less frequently, in fresh water, an indication tbat it can tolerate a wide range of chlorinity.

A cost-efficient one time password-based authentication in cloud environment using equal length cellular automata

Abstract One time password (OTP) scheme has been suggested as an efficient and simple solution for authentication in cloud computing. This paper investigates the nature of characteristics polynomials of Equal Length Cellular Automata (ELCA) and its application in OTP generation for authentication in cloud computing. In this work, primitive characteristics polynomial is identified as a crucial criterion for pseudo-randomness of ELCA cycles generated with linear rules. Novel algorithms are also designed for (i) cost effective generation of OTPs, (ii) flexible generation of equally populated OTP sets, and (iii) generation of controllable number of passwords in OTP sets. Application of linear rules in synthesis of OTPs ensures easy implementation using only modular arithmetic, which makes the proposed method truly cost efficient.

Petrology of the alkaline rocks of the Macau Volcanic Field, NE Brazil

The Macau Volcanic Field (MVF) in the Borborema Province, NE Brazil, contains multiple centres of volcanic activity of Early to Late Cenozoic ages. We present element and Sr–Nd–Pb isotope geochemical data for four of the few most prominent basalt types of this volcanic field: Serrote Preto-type, Serra Aguda-type, Pico do Cabugi-type and Serra Preta-type, in order to assess their magmatic history from source to crystallization and the evolution of the mantle beneath the Borborema Province. The basalts are basically sodic nephelinitic–basanitic–alkali olivine basalts enriched in LILE and in Nb–Ta. The Serra Preta, Cabugi and Serra Aguda types demonstrate compositions close to primitive characteristics with 10%<MgO<15wt.% and 200ppm<Ni<500ppm, and experienced limited fractional crystallization of olivine–clinopyroxene–plagioclase–oxides with negligible wall-rock assimilation. Rb/Sr and Ba/Rb constraints support the generation of SiO2-undersaturated magmas from mantle melting of amphibole-bearing peridotites with minor phlogopite. The source for the basanites and alkali basalts is estimated to be a garnet-bearing domain around the lithosphere–asthenosphere boundary (80–93km deep), while the nephelinites are derived from the adiabatic asthenosphere at ~105km with temperatures of ~1480°C. Their incompatible trace element patterns and Sr–Nd–Pb isotopic compositions are similar to FOZO and EM-type OIB magmas. From the comparison of data with those of the Ceará-Mirim dyke swarm we propose that there is a ubiquitous FOZO reservoir in the SCLM beneath the Borborema Province. This FOZO signature characterized the upwelling asthenosphere during the lithospheric extension and thinning at the opening of the Equatorial Atlantic and is clearly represented in the Mesozoic olivine tholeiites of Ceará-Mirim. The upwelled asthenosphere cooled as a rigid SCLM since the Cretaceous and has preserved its FOZO signature evident in the Macau Cenozoic basalts. The EM signatures in MVF lavas probably represent a deep component derived from metasomatizing fluid–melts that have interacted with an originally old OIB-type mantle to produce metasomatic minerals (such as K-rich amphibole, mica) with highly incompatible trace elements contents which enhanced the generation of alkaline magmas through mantle melting.

Comparative anatomy of the arm muscles of the Japanese monkey (Macaca fuscata) with some comments on locomotor mechanics and behavior.

The anatomical literature on the genus Macaca has focused mainly on the rhesus monkey. However, some aspects in the positional behaviors of the Japanese monkey may be different from those in rhesus monkey, suggesting that the anatomical details of these species are divergent. Four thoracic limbs of Macaca fuscata adults were dissected. The arm muscles in Japanese macaques are more similar to rhesus monkeys and Papio; these characteristics are closer to those of bearded capuchins than apes, indicating more proximity of this genus to New World primates. The anatomical features observed favor quadrupedal locomotor behaviors on the ground and in arboreal environments. Japanese monkeys, rhesus monkeys, and bearded capuchins, which share more primitive characteristics in their arm muscles, present features that favor both arboreal and quadrupedal locomotor behaviors, whereas apes, mainly Pan and Gorilla, which spend more time on the ground, present more quadrupedal specializations.

Biosystematic Relationships and Generalized Morphological Characteristics of Two Representative Species from Littledalea(Poaceae)

We comprehensively studied the main character differences of 40 reprehensive populations between the nearest related Littledalea racemosa and Littledalea przevalskyi by the morphological observation and anatomical analysis of leaf epidermises. L. racemosa has short rhizomes,panicle and 6- 8 florets per spikelet,while L. przevalskyi has no rhizomes,raceme and 3- 6 florets per spikelet. They belong to two different species.The former is with more primitive external morphological characteristics,while the latter has more advanced ones. The leaf epidermis consists of long cells,short cells and stomatal cells. There are also differences on the anatomical characteristics of leaf epidermises including length and width of long cells, magnitude and distribution of stomatal apparatus,shape of subsidiary cells,abundance and growing form of short cells.According to the characteristics and evolutionary of trends of leaf epidermises of two species,we inferred their evolutionary positions and relationships. There is obvious discontinuity between them. Especially,L. przevalskyi is more advanced than L. racemosa, so it might derive immediately from the latter. The biosystematic relationships of these two species are corroborated by the evolutionary trend of external morphology.

Asymmetric cell division and its role in cell fate determination in the green alga Tetraselmis indica.

The prasinophytes (early diverging Chlorophyta), consisting of simple unicellular green algae, occupy a critical position at the base of the green algal tree of life, with some of its representatives viewed as the cell form most similar to the first green alga, the 'ancestral green flagellate'. Relatively large-celled unicellular eukaryotic phytoflagellates (such as Tetraselmis and Scherffelia), traditionally placed in Prasinophyceae but now considered as members of Chlorodendrophyceae (core Chlorophyta), have retained some primitive characteristics of prasinophytes. These organisms share several ultrastructural features with the other core chlorophytes (Trebouxiophyceae, Ulvophyceae and Chlorophyceae). However, the role of Chlorodendrophycean algae as the evolutionary link between cellular individuality and cellular cooperation has been largely unstudied. Here, we show that clonal populations of a unicellular chlorophyte, Tetraselmis indica, consist of morphologically and ultrastructurally variant cells which arise through asymmetric cell division. These cells also differ in their physiological properties. The structural and physiological differences in the clonal cell population correlate to a certain extent with the longevity and function of cells.

On the determinants of firm leverage: evidence from a structural estimation

Purpose – The purpose of this paper is to investigate the phenomena of convergence and stability of leverage reported by Lemmon et al. (2008). Design/methodology/approach – A dynamic trade-off model of the firm was used to simulate investment, leverage, and payout decisions for different types of firms. From an econometric standpoint, the Efficient Method of Moments was used to recover the structural parameters. Findings – The structural model generates a leverage ratio that oscillates around a long-run, time-invariant level and consistently reproduces the convergence and stability of leverage reported by Lemmon et al. (2008). The model also suggests the causes of those observed properties of the data. That is, convergence is due to the mean-reversion of profits while stability is due to the different fundamental characteristics (e.g. capital elasticity, volatility of profits, etc.) of the firm. Practical implications – Determining the optimal capital structure of a firm is a complex problem that has challenged academics and practitioners for a long time. Understanding leverage decisions is of great importance not only for financial managers, but also for investors, such as banks, debt-holders, equity-holders, and other capital providers, who need to understand how firms make capital structure decisions in order to achieve an efficient allocation of funds. Originality/value – The author shows that the firm-specific fixed effects in leverage regressions are not related to the usual determinants (e.g. profitability, market-to-book ratio), but to the primitive characteristics of the firm (e.g. elasticity of capital in the production function, the volatility of profits, the capital depreciation rate, the income tax rate, etc.)

Detection of Compound Structures Using a Gaussian Mixture Model With Spectral and Spatial Constraints

Increasing spectral and spatial resolution of new-generation remotely sensed images necessitate the joint use of both types of information for detection and classification tasks. This paper describes a new approach for detecting heterogeneous compound structures such as different types of residential, agricultural, commercial, and industrial areas that are comprised of spatial arrangements of primitive objects such as buildings, roads, and trees. The proposed approach uses Gaussian mixture models (GMMs), in which the individual Gaussian components model the spectral and shape characteristics of the individual primitives and an associated layout model is used to model their spatial arrangements. We propose a novel expectation–maximization (EM) algorithm that solves the detection problem using constrained optimization. The input is an example structure of interest that is used to estimate a reference GMM and construct spectral and spatial constraints. Then, the EM algorithm fits a new GMM to the target image data so that the pixels with high likelihoods of being similar to the Gaussian object models while satisfying the spatial layout constraints are identified without any requirement for region segmentation. Experiments using WorldView-2 images show that the proposed method can detect high-level structures that cannot be modeled using traditional techniques.