Modelling of soldier fly halteres for gyroscopic oscillations

Nature has evolved a beautiful design for small-scale vibratory rategyro in the form of dipteran halteres that detect body rotations via Coriolis acceleration. In most Diptera, including soldier fly, Hermetia illucens, halteres are a pair of special organs, located in the space between the thorax and the abdomen. The halteres along with their connecting joint with the fly's body constitute a mechanism that is used for muscle-actuated oscillations of the halteres along the actuation direction. These oscillations lead to bending vibrations in the sensing direction (out of the haltere's actuation plane) upon any impressed rotation due to the resulting Coriolis force. This induced vibration is sensed by the sensory organs at the base of the haltere in order to determine the rate of rotation. In this study, we evaluate the boundary conditions and the stiffness of the anesthetized halteres along the actuation and the sensing direction. We take several cross-sectional SEM (scanning electron microscope) images of the soldier fly haltere and construct its three dimensional model to get the mass properties. Based on these measurements, we estimate the natural frequency along both actuation and sensing directions, propose a finite element model of the haltere's joint mechanism, and discuss the significance of the haltere's asymmetric cross-section. The estimated natural frequency along the actuation direction is within the range of the haltere's flapping frequency. However, the natural frequency along the sensing direction is roughly double the haltere's flapping frequency that provides a large bandwidth for sensing the rate of rotation to the soldier flies.

Compressive and Flexural Properties of Functionally Graded Fly Ash Cenosphere-Epoxy Resin Syntactic Foams

The present study focuses on developing functionally graded syntactic foams (FGSFs) based on a layered co-curing technique. The FGSFs were characterized for compressive and flexural properties and compared with plain syntactic foams. The results showed that the specific compressive modulus was 3-67% higher in FGSFs compared to plain syntactic foams. FGSF exhibited 5-34% and 34-87% higher specific modulus and strength, respectively in flexural mode. The microscopic examinations of comparative responses of the filler and matrix to deformation suggest that the failure is dominated by the matrix. The gradient in the composition of syntactic foams helps in effectively distributing the stress throughout the microstructure and results in improved mechanical performance of syntactic foams. From the microscopy studies, it is evident that, the failure mechanism in the FGSF under flexural loading is governed by a crack that initiated on the tensile side of the specimen and propagated through the thickness to cause complete fracture. The microscopic observations further clearly demonstrate the existence of seamless interfaces between the layers and a clear difference in the cenosphere concentration across the interface, affirming the gradation in the prepared samples. The results show that appropriate compositions of FGSFs can be selected to develop materials with improved mechanical performance. POLYM. COMPOS., 36:685-693, 2015. (c) 2014 Society of Plastics Engineers

Fly ash cenospheres as reinforcement in different polymer composites - a comparative study of physical and mechanical properties

The work reports the preparation of fly ash cenospheres bearing polymer composites, using various polymer matrix materials namely, low density polyethylene, high density polyethylene, polystyrene and polymethylmethacrylate followed by evaluation of properties. The composites are synthesized by including about 18% by weight fly ash cenospheres, into various polymer matrices using brabender facility in the temperature range 120-160 degrees C and at a mixing pressure of 50 MPa. Subsequently, they are cast into sheets through compression moulding. The test samples, made from the sheets, are characterized for physical as well as mechanical properties such as density, hardness, compression strength, impact response, wear and friction. The investigation reveals that the addition of fly ash cenospheres to various polymer matrices results in reduction of density. Further, improvements in the slide wear resistance and decrease in the co-efficient of friction values are noticed. As for interpreting the slide wear data, recourse to examination under scanning electron microscope is made in this paper. As regards the mechanical properties, hardness increases while the compression strength and impact energy decreases with inclusion of cenospheres in all the four types of samples investigated.

The Asian elephant is amongst the top three frugivores of two tree species with easily edible fruit

Large animal species are prone to local extirpation, but ecologists cannot yet predict how the loss of megaherbivores affects ecosystem processes such as seed dispersal. Few studies have compared the quantity and quality of seed dispersal by megaherbivores versus alternative frugivores in the wild, particularly for plant species with fruit easily consumed by many frugivorous species. In a disturbed tropical moist forest in India, we examine whether megaherbivores are a major frugivore of two tree species with easily edible, mammal-dispersed fruit. We quantify the relative fruit removal rates of Artocarpus chaplasha and Careya arborea, by the Asian elephant (Elephas maximus) and alternative dispersers. Through focal watches and camera trapping, we found the elephant to be amongst the top three frugivores for each tree species. Furthermore, seed transects under A. chaplasha show that arboreal frugivores discard seeds only a short distance from the parental tree, underscoring the elephant's role as a long-distance disperser. Our data provide unprecedented support for an old notion: megaherbivores may be key dispersers for a broad set of mammal-dispersed fruiting species, and not just fruit inaccessible to smaller frugivores. As such, the elephant may be particularly important for the functional ecology of the disturbed forests it still inhabits across tropical Asia.

Fruit Trait Preference in Rhesus Macaques (Macaca mulatta) and its Implications for Seed Dispersal

Primates constitute 25-40 % of the frugivore biomass of tropical forests. Primate fruit preference, as a determinant of seed dispersal, can therefore have a significant impact on these ecosystems. Although the traits of fruits included in primate diets have been described, fruit trait preference has been less studied with respect to fruit availability. We examined fruit trait preference and its implications for seed dispersal in the rhesus macaque (Macaca mulatta), a dietarily flexible species and important seed disperser, at the Buxa Tiger Reserve, India. Over a year, we monitored the phenology of selected trees in the study area, observed the feeding behavior of rhesus macaques using scans and focal animal sampling, and documented morphological traits of the fruits/seeds consumed. Using generalized linear modeling, we found that the kind of edible tissue was the chief determinant of fruit consumption, with M. mulatta feeding primarily on fruits with juicy-soft pulp and acting as seed predators for those with no discernible pulp. Overall, the preferred traits were external covers that could be easily pierced by a fingernail, medium to large seeds, true stone-like seeds, and juicy-soft edible tissue, thereby implying that fruit taxa with these traits had a higher probability of being dispersed. Macaques were more selective during the high fruit availability period than the low fruit availability period, preferentially feeding on soft-skinned fruits with juicy-soft pulp. We suggest that further studies be conducted across habitats and time to understand the consistency of interactions between primates and fruits with specific traits to determine the degree of selective pressure (if any) that is exerted by primates on fruit traits.

Combining Plant Pathogenic Fungi and the Leaf-Mining Fly, Hydrellia pakistanae, Increases Damage to Hydrilla

Four fungal species, F71PJ Acremonium sp., F531 Cylindrocarpon sp., F542, Botrytis sp., and F964 Fusarium culmorum [Wm. G. Sm.] Sacc. were recovered from hydrilla [ Hydrilla verticillata (L. f.) Royle] shoots or from soil and water surrounding hydrilla growing in ponds and lakes in Florida and shown to be capable of killing hydrilla in a bioassay. The isolates were tested singly and in combination with the leaf-mining fly, Hydrellia pakistanae (Diptera: Ephydridae), for their capability to kill or severely damage hydrilla in a bioassay.

Written words turned into moving Images: Jeanette Winterson translates "Oranges Are Not the Only Fruit for the Screen"

Eterio Pajares, Raquel Merino y José Miguel Santamaría (eds.)

Histoire de Portugal : contenant les enterprises, navigations, & gestes memorables des Portugallois, tant en la cõqueste des Indes Orientales par eux descouvertes, qu'és guerres d'Afrique & autres exploits, depuis l'an mil quatre cens nonãte six, jusques à l'an mil cinq cens septante huit, sous Emmanuel premier, Jean troisieme, & Sebastian premier du nom / Pour Antoine Chuppin, ed. ; comprinse en vingt livres, dont les douze premiers sont traduits du latin de Ierosme Osorius, Euesque de Sylues en Algarve, les huit suivans prins de Lopez de Castagnede & d'autres historiensNouvellement mise en françois, par S.G.S. avec un discours du fruit qu'on peut recueillir de la lecture de cette histoire, & ample indice des matieres principales y contenues

Contém os empreendimentos, as navegações e os gestos memoráveis dos portugueses, inclusive em suas colônias.

The formation mechanism of low leaching glassy slag during plasma arc vitrification treatment of fly ash

In this paper, the glass formation theory is applied to study the formation mechanism of the low leaching glassy slag during the process of plasma waste treatment. The research shows that SiO2 acts as network former to form a 3-dimensional Si-O tetrahedral network in which heavy metals are bonded or encapsulated, so the Si-O tetrahedron protect heavy metals against leaching from the vitrified slag or acid corrosion. For given chemical compositions of waste, the formation ability of the vitrified slag can be represented by the ratio of the whole oxygen ions to the whole network former ions in glass (O/Si) which is appropriate in the range of 2~3. A plasma arc reactor is used to conduct the vitrification experiments of two kinds of fly ashes with additives in which effects of various parameters including arc power, cooling speed, treatment temperature are studied. The chemical compositions of fly ashes are analyzed by X-ray fluorescence (XRF) spectrometry. The experimental results show that both cooling speed and O/Si have important influence on the formation of the vitrified slag, which is qualitatively in accordance with the predictions of the glass formation theory.

A computer-aided investigation of motion detection units in the fly

This work deals with two related areas: processing of visual information in the central nervous system, and the application of computer systems to research in neurophysiology.

Certain classes of interneurons in the brain and optic lobes of the blowfly Calliphora phaenicia were previously shown to be sensitive to the direction of motion of visual stimuli. These units were identified by visual field, preferred direction of motion, and anatomical location from which recorded. The present work is addressed to the questions: (1) is there interaction between pairs of these units, and (2) if such relationships can be found, what is their nature. To answer these questions, it is essential to record from two or more units simultaneously, and to use more than a single recording electrode if recording points are to be chosen independently. Accordingly, such techniques were developed and are described.

One must also have practical, convenient means for analyzing the large volumes of data so obtained. It is shown that use of an appropriately designed computer system is a profitable approach to this problem. Both hardware and software requirements for a suitable system are discussed and an approach to computer-aided data analysis developed. A description is given of members of a collection of application programs developed for analysis of neuro-physiological data and operated in the environment of and with support from an appropriate computer system. In particular, techniques developed for classification of multiple units recorded on the same electrode are illustrated as are methods for convenient graphical manipulation of data via a computer-driven display.

By means of multiple electrode techniques and the computer-aided data acquisition and analysis system, the path followed by one of the motion detection units was traced from open optic lobe through the brain and into the opposite lobe. It is further shown that this unit and its mirror image in the opposite lobe have a mutually inhibitory relationship. This relationship is investigated. The existence of interaction between other pairs of units is also shown. For pairs of units responding to motion in the same direction, the relationship is of an excitatory nature; for those responding to motion in opposed directions, it is inhibitory.

Experience gained from use of the computer system is discussed and a critical review of the current system is given. The most useful features of the system were found to be the fast response, the ability to go from one analysis technique to another rapidly and conveniently, and the interactive nature of the display system. The shortcomings of the system were problems in real-time use and the programming barrier—the fact that building new analysis techniques requires a high degree of programming knowledge and skill. It is concluded that computer system of the kind discussed will play an increasingly important role in studies of the central nervous system.