Outermost Ones Research Articles

Wing and tail feather damage in Western Common Kingfishers Alcedo atthis ispida in relation to moult

ABSTRACT Feathers have to be moulted to repair sustained damage. Our objective is to understand the relationship between the frequency of feather damage, feather sturdiness and moult sequence. Damage was recorded in five flight feather tracts for over 2000 Common Kingfishers Alcedo atthis ispida captured during a population study in northwestern Germany. We found that, of the feather tracts studied before the first moult, the tail feathers sustained most wear and damage, especially the more sturdily built outermost ones. Nevertheless, the probability of moulting a rectrix decreased from the central pair to the outside, while the damage risk increased. The sturdy distal primaries and the more lightly built innermost secondaries were the remiges with the highest frequency of damage, but not the most severe damage, while a row of midwing secondaries and primaries had the lowest damage risk. Where remiges had been retained when moult was suspended at the beginning of winter, about 75% of unmoulted feathers belonged to this low-risk group. The distal alula feather and the outermost primary covert had damage rates comparable to the low-risk row of remiges. Feather damage in the wings does not accumulate evenly over time, but increased markedly from March to April, coinciding with courtship and nest excavation, especially in females. Ultraviolet light seems to be an important factor for the observed feather deterioration, but is not the only one. The Kingfisher’s unusual moult sequence of remiges and primary coverts matches the distribution pattern of feather damage, but the sequence of the first tail-feather moult does not. Very few previous studies have investigated the relationship between patterns of feather damage and moult sequence. We hope this work encourages more investigation of this subject.

Influences of summer warming and nutrient availability on Salix glauca L. growth in Greenland along an ice to sea gradient

The combined effects of climate change and nutrient availability on Arctic vegetation growth are poorly understood. Archaeological sites in the Arctic could represent unique nutrient hotspots for studying the long-term effect of nutrient enrichment. In this study, we analysed a time-series of ring widths of Salix glauca L. collected at nine archaeological sites and in their natural surroundings along a climate gradient in the Nuuk fjord region, Southwest Greenland, stretching from the edge of the Greenlandic Ice Sheet in the east to the open sea in the west. We assessed the temperature-growth relationship for the last four decades distinguishing between soils with past anthropogenic nutrient enrichment (PANE) and without (controls). Along the East–West gradient, the inner fjord sites showed a stronger temperature signal compared to the outermost ones. Individuals growing in PANE soils had wider ring widths than individuals growing in the control soils and a stronger climate-growth relation, especially in the inner fjord sites. Thereby, the individuals growing on the archaeological sites seem to have benefited more from the climate warming in recent decades. Our results suggest that higher nutrient availability due to past human activities plays a role in Arctic vegetation growth and should be considered when assessing both the future impact of plants on archaeological sites and the general greening in landscapes with contrasting nutrient availability.

Seasonality in carbon chemistry of Cochin backwaters

Seasonality in carbon chemistry of Cochin backwaters, Southern India, was investigated between 2018 and 2019. Dissolved inorganic carbon (DIC) showed strong seasonal variations. Lowest DIC was observed during the Southwest Monsoon (SWM), in conjunction with low salinity in surface waters, suggesting strong freshwater influence. The maximum concentration of partial pressure of carbon dioxide in water (pCO2w) was recorded from polluted waters of Vembanad Lake (∼16,000 μatm). Excluding the SWM, the inner most stations (freshwater) showed lower pCO2w levels compared with the outermost (estuarine) ones. With regard to sampling stations, all the environmental properties, except silicate and phosphate, exhibited significant variation, pointing to large spatial heterogeneity across the stations. Salinity showed a strong correlation with dissolved inorganic carbon within the Cochin backwaters. High pH and low pCO2w observed in some of the inner most stations indicates role of pH in carbonate speciation. Our study indicates large seasonal fluctuation in biogeochemical parameters and strong heterogeneity between individual stations which therefore necessitates development of local biogeochemical models for better understanding of carbon budget in these waters.

Nested Named Entity Recognition via Second-best Sequence Learning and Decoding

When an entity name contains other names within it, the identification of all combinations of names can become difficult and expensive. We propose a new method to recognize not only outermost named entities but also inner nested ones. We design an objective function for training a neural model that treats the tag sequence for nested entities as the second best path within the span of their parent entity. In addition, we provide the decoding method for inference that extracts entities iteratively from outermost ones to inner ones in an outside-to-inside way. Our method has no additional hyperparameters to the conditional random field based model widely used for flat named entity recognition tasks. Experiments demonstrate that our method performs better than or at least as well as existing methods capable of handling nested entities, achieving F1-scores of 85.82%, 84.34%, and 77.36% on ACE-2004, ACE-2005, and GENIA datasets, respectively.

An alternative method for refined process structure trees (RPST)

PurposeThe refined process structure tree (RPST), the hierarchy of non-overlapping single-entry single-exit (SESE) regions of a process model, has been utilized for better comprehension and more efficient analysis of business process models. Existing RPST methods, based on the triconnected components of edges, fail to identify a certain type of SESE region. The purpose of this paper is to introduce an alternative method for generating a complete RPST utilizing rather simple techniques.Design/methodology/approachThe proposed method first focuses on the SESE regions of bonds and rigids, from the innermost ones to the outermost ones, utilizing dominance and post-dominance relations. Then, any SESE region of a series nested in a bond or a rigid is identified with a depth-first search variation. Two-phase algorithms and their completeness proofs, a software tool incorporating visualization of stepwise outcomes, and the experimental results of the proposed method are provided.FindingsThe proposed method utilizes simple techniques that allow their straightforward implementation. Visualization of stepwise outcomes helps process analysts to understand the proposed method and the SESE regions. Experiments with 604 SAP reference models demonstrated the limitation of the existing RPST methods. The proposed method, however, completely identified all types of SESE regions, defined with nodes, in less computation time than with the old methods.Originality/valueEach triconnected component of the undirected version of a process model is associated with a pair of boundary nodes without discriminating between the entry and the exit. Here, each non-atomic SESE region is associated with two distinct entry and exit nodes from the original model in the form of a directed graph. By specifying the properties of SESE regions in more comprehensible ways, this paper facilitates a deeper understanding of SESE regions rather than relying on the resulting RPST.

Nearly coeval intermediate-age Milky Way star clusters at very different dynamics evolutionary stages

ABSTRACT We report astrophysical properties of 12 Milky Way open clusters located beyond a 2 kpc circle around the Sun by using deep optical photometry. We estimated their age and metallicities on the basis of a maximum likelihood approach using astrometric members determined from Gaia DR2 data. The studied clusters turned out to be of intermediate-age (0.8–4.0 Gyr), with metallicities spanning the range [Fe/H] ∼ −0.5–+0.1 dex, and distributed within the general observed trend of the Milky Way disc radial and perpendicular metallicity gradients. As far as we are aware, these are the first metal abundance estimates derived for these clusters so far. From the constructed stellar density radial profiles and cluster mass functions we obtained a variety of structural and internal dynamics evolution parameters. They show that while the innermost cluster regions would seem to be mainly shaped according to the respective internal dynamics evolutionary stages, the outermost ones would seem to be slightly more sensitive to the Milky Way tidal field. The nearly coeval studied clusters are experiencing different levels of two-body relaxation following star evaporation; those at more advanced stages being more compact objects. Likewise, we found that the more important the Milky way tides, the larger the Jacobi volume occupied by the clusters, irrespective of their actual sizes and internal dynamics evolutionary stages.

Analysis of Deck Slab of Reinforced Concrete Gerber-Girder Bridge Widened by Addition of Continuous Steel-Concrete Composite Girders

Many Gerber-girder bridges have become obsolete in terms of deck width and load carrying capacity. If bridge replacement is not necessary, additional girders are installed. Sometimes, due to erection convenience, the added girders do not replicate the static scheme of the refurbished structure. Such an arrangement requires special attention to preserve structural durability. An example of the inappropriate arrangement of the widening of a Reinforced Concrete Gerber-girder road bridge is presented together with an alternative concept of refurbishment based on the addition of the continuous steel-concrete girders as the outermost ones. The added deck slab connects the added and the existing parts of the structure. Attention is drawn the static analysis of the added deck slab and the influence of the added outermost girders that do not replicate the static scheme of the existing ones. Due to different static schemes of the existing and the added girders, the traditional method of the deck slab analysis is inappropriate. The Finite Element 3D model is to be applied to access bending moments in the deck slab spans correctly. It is shown that: a) the analysis of the distribution of the bending moments in the existing and the added slab spans, especially near Gerber-hinges, should be based on the Finite Element 3D modelling; b) the analysis should consider live loads acting on the whole width of the Gerber-hinge span; c) the bending moment distribution in the widened deck slab is sensitive to the distance to the Gerber hinge.

Mercury speciation in Pinus nigra barks from Monte Amiata (Italy): An X-ray absorption spectroscopy study

This study determined, by means of X-ray absorption near-edge structure (XANES) spectroscopy, the speciation of mercury (Hg) in black pine (Pinus nigra) barks from Monte Amiata, that were previously shown to contain exceptionally high (up to some mg kg−1) Hg contents because of the proximity to the former Hg mines and roasting plants. Linear fit combination (LCF) analysis of the experimental spectra compared to a large set of reference compounds showed that all spectra can be fitted by only four species: β-HgS (metacinnabar), Hg-cysteine, Hg bound to tannic acid, and Hg0. The first two are more widespread, whereas the last two occur in one sample only; the contribution of organic species is higher in deeper layers of barks than in the outermost ones. We interpret these results to suggest that, during interaction of barks with airborne Hg, the metal is initially mechanically captured at the bark surface as particulate, or physically adsorbed as gaseous species, but eventually a stable chemical bond is established with organic ligands of the substrate. As a consequence, we suggest that deep bark Hg may be a good proxy for long term time-integrated exposure, while surface bark Hg is more important for recording short term events near Hg point sources.

SDSS IV MaNGA: the global and local stellar mass assemby histories of galaxies

By means of the fossil record method implemented through Pipe3D, we reconstruct the global and radial stellar mass growth histories (MGHs) of an unprecedentedly large sample of galaxies, ranging from dwarf to giant objects, from the "Mapping Nearby Galaxies at the Apache Point Observatory" survey. We confirm that the main driver of the global MGHs is mass, with more massive galaxies assembling their masses earlier (downsizing), though for a given mass, the global MGHs segregate by color, specific star formation rate (sSFR), and morphological type. From the inferred radial mean MGHs, we find that at the late evolutionary stages (or for fractions of assembled mass larger than ~ 80%), the innermost regions formed stars on average earlier than the outermost ones (inside-out). At earlier epochs, when the age resolution of the method becomes poor, the mass assembly seems to be spatially homogeneous or even in the outside-in mode, specially for the red/quiescent/early-type galaxies. The innermost MGHs are in general more regular (less scatter around the mean) than the outermost ones. For dwarf and low-mass galaxies, we do not find evidence of an outside-in formation mode; instead their radial MGHs are very diverse most of the time, with periods of outside- in and inside-out modes (or strong radial migration), suggesting this an episodic SF history. Blue/star-forming/late-type galaxies present on average a significantly more pronounced inside-out formation mode than red/quiescent/early-type galaxies, independently of mass. We discuss our results in the light of the processes of galaxy formation, quenching, and radial migration. We discuss also on the uncertainties and biases of the fossil record method and how they could affect our results.

Stacking of capacitive cells for electrical energy production by salinity exchange

In this paper we explore methods for stacking individual cells in order to increase the amount of energy that can be extracted from salinity gradient cycles (capmix methods). Each of the cells consists of a pair of parallel electrodes made of activated carbon particles, either bare or coated by a layer of polyelectrolyte. In these methods, energy is produced based on the modifications of the electrical double layer (EDL) structure in the pores of the carbon particles upon exchange of the salinity of the surrounding medium. In the case of the bare carbon particles, the electrodes are externally charged in presence of high-salt concentration, and discharged after exchanging the solution for a dilute one (sea-vs. river-water cycles). In a first stacking approach, we simply connect the electrodes side-by-side and only the outermost ones can be connected to the external source. Using a stack where potential and current between cells can be measured, it is shown that only the external electrodes seem to work, and it is suggested that this is a consequence of internal short-circuit currents between oppositely charged electrodes of different cells through the electrolyte. In contrast, the side-by-side configuration is operational if coated electrodes are used.

Resonant spin-wave modes in trilayered magnetic nanowires studied in the parallel and antiparallel ground state

Brillouin light scattering has been utilized to study the field dependence of resonant spin-wave modes in layered NiFe(30nm)/Cu(10nm)/NiFe(15nm)/Cu(10nm)/NiFe(30nm) nanowires of rectangular cross section, 150nm wide and formed in arrays that are spaced laterally by 400nm. The major and minor longitudinal hysteresis curves have been measured by the magneto-optical Kerr effect technique, with applied field parallel to the length of the nanowires. The light-scattering spectra were recorded as a function of the magnetic field strength, encompassing both the parallel and antiparallel alignments of the middle stripe with respect to the magnetization direction of the outermost ones. The field ranges for the antiparallel state are different from those for the parallel case, while the mode frequencies change abruptly at the parallel-to-antiparallel transition field (and vice versa). The modes detected in the antiparallel state are found to have only a weak dependence on the applied magnetic field, whether along the major or minor hysteresis curves, while in the parallel state the mode frequencies monotonically increase with the applied magnetic field. The experimental results have been successfully interpreted, across the whole range of the magnetic fields investigated, in terms of the mode localizations across the width and in the layered structure. This was accomplished by means of a microscopic (Hamiltonian-based) theory, which has been extended here to the case of non-parallel magnetic ground states.

Field dependence of the magnetic eigenmode frequencies in layered nanowires with ferromagnetic and antiferromagnetic ground states: experimental and theoretical study

The magnetic field dependence of the magnetic eigenmode frequencies in 150 nm wide layered permalloy nanowires (NWs) has been studied by the Brillouin light scattering technique. The NWs have the following layering structure Py(30 nm)/Cu(10 nm)/Py(d)/Cu(10 nm)/Py(30 nm) with fixed thickness of the top and bottom stripe and differ by the thickness d of the middle Py stripe (with d = 15, 30, 60 nm). The magnetic field, applied along the length of the wires, has been swept from positive to negative saturation thus exploring both the ferromagnetic and the antiferromagnetic relative orientation of the magnetization in the middle stripe with respect to the outermost ones. In conjunction with the transition between the two different ground states, the mode frequencies undergo an abrupt variation. Moreover the mode frequencies in the antiferromagnetic state are relatively insensitive to the applied field strength. The experimental results (frequencies versus magnetic field strength) have been successfully interpreted by means of a microscopic (Hamiltonian-based) theory which incorporates both the exchange and dipole–dipole interactions as well as effects of single-ion anisotropy and an external magnetic field applied parallel to the NW axis. This model was extended to account for parallel and antiparallel magnetization orientations in the layered NWs, enabling us to also calculate the probability amplitude of each spin-wave eigenmode at any position in the trilayered NWs.

Superconducting Analogue of the Parafermion Fractional Quantum Hall States

Read and Rezayi $Z_k$ parafermion wavefunctions describe $\nu=2+\frac{k}{kM+2}$ fractional quantum Hall (FQH) states. These states support non-Abelian excitations from which protected quantum gates can be designed. However, there is no experimental evidence for these non-Abelian anyons to date. In this paper, we study the $\nu=2/k$ FQH-superconductor heterostructure and find the superconducting analogue of the $Z_k$ parafermion FQH state. Our main tool is the mapping of the FQH into coupled one-dimensional (1D) chains each with a pair of counter-propagating modes. We show that by inducing intra-chain pairing and charge preserving backscattering with identical couplings, the 1D chains flow into gapless $Z_{k}$ parafermions when $k< 4$. By studying the effect of inter-chain coupling, we show that every parafermion mode becomes massive except for the two outermost ones. Thus, we achieve a fractional topological superconductor whose chiral edge state is described by a $Z_k$ parafermion conformal field theory. For instance, we find that a $\nu=2/3$ FQH in proximity to a superconductor produces a $Z_3$ parafermion superconducting state. This state is topologically indistinguishable from the non-Abelian part of the $\nu=12/5$ Read-Rezay state. Both of these systems can host Fibonacci anyons capable of performing universal quantum computation through braiding operations.

Abundance Gradients and the Formation of the Milky Way

In this paper we adopt a chemical evolution model, which is an improved version of the Chiappini, Matteucci, & Gratton model, assuming two main accretion episodes for the formation of the Galaxy, the first forming the halo and bulge in a short timescale and the second one forming the thin disk, with a timescale that is an increasing function of the Galactocentric distance (being of the order of 7 Gyrs at the solar neighborhood). The present model takes into account in more detail than previously the halo density distribution and explores the effects of a threshold density in the star formation process during both the halo and disk phases. The model also includes the most recent nucleosynthesis prescriptions concerning supernovae of all types, novae, and single stars dying as white dwarfs. In the comparison between model predictions and available data, we have focused our attention on abundance gradients as well as gas, stellar, and star formation rate distributions along the disk, since this kind of model has already proven to be quite successful in reproducing the solar neighborhood characteristics. We suggest that the mechanism for the formation of the halo leaves detectable imprints on the chemical properties of the outer regions of the disk, whereas the evolution of the halo and the inner disk are almost completely disentangled. This is due to the fact that the halo and disk densities are comparable at large Galactocentric distances and therefore the gas lost from the halo can substantially contribute to building up the outer disk. We also show that the existence of a threshold density for the star formation rate, both in the halo and disk phase, is necessary to reproduce the majority of observational data in the solar vicinity and in the whole disk. In particular, a threshold in the star formation implies the occurrence of a gap in the star formation at the halo-disk transition phase, in agreement with recent data. We conclude that a relatively short halo formation timescale (0.8 Gyr), in agreement with recent estimates for the age differences among Galactic globular clusters, coupled with an inside-out formation of the Galactic disk, where the innermost regions are assumed to have formed much faster than the outermost ones, represents, at the moment, the most likely explanation for the formation of the Milky Way. This scenario allows us to predict abundance gradients and other radial properties of the Galactic disk in very good agreement with observations. Moreover, as a consequence of the adopted inside-out scenario for the disk, we predict that the abundance gradients along the Galactic disk must have increased with time and that the average ratios in stars (halo plus disk) slightly decrease going from 4 to 10 kpcs from the Galactic center. We also show that the same ratios increase substantially toward the outermost disk regions and the expected scatter in the stellar ages decreases, because the outermost regions are dominated by halo stars. More observations at large Galactocentric distances are needed to test these predictions.

Illusions as neuro-signs

The term ‘visual illusion’ is mainly associated with a set of figures produced in the late nineteenth century, when the likes of Zöllner and Poggendorff described their eponymous phenomena (see Curr Biol 1998, 8:R509). Müller-Lyer described his illusion in 1889 and a variant of it is shown below. The vertical line is bisected by the lower corner of the diamond but the lower half looks considerably longer than the upper half. This simple and compelling illusion of length has been studied experimentally perhaps more than any other but its basis remains elusive. An illusion like the blue and grey one below was illustrated by Wundt in 1898 (although it is called the Titchener illusion). The two grey discs are the same size but the size contrast with the surrounding ones results in their perceptual inequality. The last figure is a variant of the illusion published by Ponzo in 1912. Converging lines provide powerful allusions to depth or distance in pictures and they can have distorting effects on our judgments of size. The outline circles throughout the figure are the same size but the outermost ones appear largest. The circles also appear distorted in shape because of the angles at which they intersect the inclined lines. Visual illusions are generally classified as distortions of orientation or size and, for a long time, the former have been taken to provide the better indications of neural function (in this series, referred to as neuro-signs). But the situation is now changing. In the past decade, functional distinctions between two pathways of neural processing in the visual cortex have been made. These are called the dorsal and ventral streams (see Curr Biol 1998, 8:R489–R491). Perceiving the location of an object was attributed to the dorsal stream, whereas the ventral stream determined its identity — the ‘where’ and ‘what’ dimensions of vision. A recent interpretation of these streams has been added in terms of perception and action: the dorsal stream is said to be concerned with motor control and the ventral with perceptual representation. The difference between the way illusions of size look to us and the way we respond to them is taken to support the latter distinction. Whereas our perception is distorted by these patterns, our motor control is not. If discs were placed on the grey circles in the blue and grey figure, in order to pick them up, observers would adjust their fingers to the appropriate physical width rather than to their perceived inequality. Thus, we might be able to fool the eye, but not the fingers. N Wade, Department of Psychology, University of Dundee, Dundee DD1 4HN, UK.

A New Species of Xylopia (Annonaceae) from Southern Venezuela

Xylopia plowmanii is newly described from plants from Estado Apure and Estado Amazonas, Venezuela. It most closely resembles a group of emarginate-leaved species that includes X. emarginata, X. spruceana, and X. venezuelana. During the preparation of the Annonaceae treatment for the upcoming Flora of the Venezuelan Guayana, the following new species of Xylopia was recognized and is described below. Xylopia plowmanii P. E. Berry & D. Johnson, sp. nov. TYPE: Venezuela. Amazonas: Tobogan de la Selva, along Rio Coromoto, 35 km S of Puerto Ayacucho, approximately 5?22'N, 67?33'W, T. Plowman & F. Gudnchez 13523 (holotype, MO; isotypes, F, NY, U). Figure 1. Species Xylopiae emarginatae Martius, X. spruceanae Bentham et X. venezuelanae R. E. Fries proxima, differt vero: caulibus juvenilibus sparse adpresseque puberulentibus deinde subglabratis, foliis latioribus atque elliptico-oblongis, pagina inferiore glabris, excepta costa adpresse strigosa, calyce glabro leviter lobato, 2 mm longo, 3.5-4.5 mm lato, petalis exterioribus 14.5-18 mm longis, dorso inconspicue adpresso-pubescentibus, petalis interioribus 14-20(-24) mm longis. Tree 12-16(-20) m tall. Leaf-bearing twigs 0.82.8 mm thick, brown to grayish brown, at first finely appressed-puberulent, later becoming glabrate, lenticellate. Blades of mature leaves 5-8 cm long, 23 cm wide, subcoriaceous, discolorous, oblong to elliptic-oblong, rounded and conspicuously emarginate at the apex, narrowed toward the base but angled sharply 2-4 mm from the petiole, making the base obliquely truncate, glabrous except for midrib, which is strigose abaxially with hairs 1-2 mm long; midrib impressed adaxially, raised abaxially; secondary veins faint, 7-9 per side, at 60-70? angle to midrib, slightly raised on both surfaces of the blade, anastomosing ca. 3 mm from the margin; petioles 3-4 mm long, 1.1-1.3 mm wide, terete, shallowly canaliculate and pubescent adaxially, glabrous abaxially. Flowers axillary, commonly two (sometimes three) per axil; inflorescence axis below articulation with pedicel 1-2.2 mm long, 1.1-1.3 mm thick; pedicel 2.8-4 mm long, 0.7-0.8 mm thick at midpoint, with an amplexicaul bract attached 1.2-1.5 mm above the articulation; bract 0.9-1 mm long, 1-1.3 mm wide, quadrate to semicircular. Calyx cuplike, 3.5-4.5 mm diam., divided to about the midpoint into broadly triangular lobes 1.5-2 mm long, glabrous. Petals pale yellow adaxially, orange except for the yellowish base abaxially; outer petals 14.5-18 mm long at maturity, 2 mm wide at midpoint, strap-shaped, widening to 3 mm at base, base concave, apex obtuse, densely puberulent adaxially, very sparsely appressed-puberulent abaxially; inner petals subequal in length to outer ones and similar in shape or exceptionally to 24 mm long, 1.2 mm wide at midpoint, 2 mm wide at base, puberulent along the midvein adaxially, uniformly puberulent abaxially. Stamens numerous, 1-1.4 mm long, 0.20.4 mm wide, the outermost ones converted into staminodes 0.9-1.2 mm long, 0.4-0.5 mm wide; connectives dome-shaped, short conic or truncate, papillate; filaments 0.4 mm long. Carpels 6-10, l near; ovaries 0.9-1 mm long, pubescent; style/stigma 4.2-4.8 mm long, linear, with a few sparse hairs along edges; ovules 4 in a single row. Torus in flower 2.1 mm diam., the stamens leaving raised scars on the torus surface, the center of the torus excavated, with the ovaries concealed within the cavity with only the styles exserted. Pedicel in fruit 10 mm long, 2 mm wide, glabrate. Monocarps 4-6, stipitate, the seed-containing portion 1.9-2.8 cm long, 1-1.8 cm wide, irregularly ovoid, densely covered by a matted, ferruginous indument, turning brown and glabrescent at maturity; stipes 4-7 mm long, 1.5-2 mm wide. Seeds usually 3 per monocarp, at 60? angle to long axis of monocarp, 6.57.5 mm long, 4-5 mm wide, ellipsoid, smooth; aril bilobed. Distribution. Southern Estado Apure and northwestern Estado (formerly Territorio Federal) AmaNOVON 3: 99-101. 1993. This content downloaded from 207.46.13.75 on Sat, 03 Sep 2016 04:39:39 UTC All use subject to http://about.jstor.org/terms

Cytochemical aspects of fungal penetration, haustorium formation and interfacial material in rose leaves infected by Sphaerotheca pannosa var. rosae

Fungal development and host reactions induced in rose leaf epidermal cells by the powdery mildew fungus, Sphaerotheca pannosa var. rosae , were examined on the basis of ultrastructure and of cytochemistry of chitin, pectin, and cellulose subunits. Fungal growth in the epidermis was associated with the formation of haustoria which appeared multilobed and delimited by an extrahaustorial membrane probably originating from the host plasmalemma. The extrahaustorial matrix was free of chitin as judged by the absence of labelling following incubation with a wheat germ agglutinin/ovomucoid-gold complex. Similarly, neither pectin nor cellulose was detected in this matrix, whereas these compounds were abundant in host cell walls. Various host reactions were observed at sites of fungal penetration. The formation of papillae was often associated with a restricted development of the infection peg. The most striking reaction was the occurrence of successive layers of a fibrillar material, forming a collar around the haustorial neck. Our cytochemical observations demonstrated that the collar was made of an amorphous material surrounded by fibrillar layers, the outermost ones being cellulose-rich. The possible nature and origin of this structure is discussed in relation to its possible involvement in resistance to fungal attack.

Calcium phosphate deposits in domes of human pancreatic adenocarcinoma (Capan-1) cell cultures

Human pancreatic cells of the Capan-1 line form domes in culture during the stationary growth stage. The domes are thought to be a result of the transport of water and electrolytes by the Capan-1 cells. In older Capan-1 cultures, the epithelial sheets formed thickenings from several layers of cells of which the outermost ones were joined by tight type junctions. In the intracellular space, deposits of insoluble calcium salts were observed. Culture of Capan-1 cells in the presence of fibroblasts prolonged survival of the cultures with intact domes for more than 80 days. The Capan-1 cells proliferated forming multilayers and closed cavities which we called super-domes. X-ray spectrometry and electron diffraction analysis showed that the abundant deposits inside these cavities consisted of calcium phosphate in an apatite structure. The number of these deposits increased with time in culture, and they appeared to be formed at the sites of contact with an extracellular matrix consisting of cell debris. Deposits were not observed within the culture medium. Cells from domes were stained cytochemically for ATPases and alkaline phosphatases and examined by light and electron microscopy. The Capan-1 cells surrounding the domes were differentiated, polarized cells containing placental type alkaline phosphatases on their apical membranes and Ca 2+-ATPases on their basolateral membranes. These enzymes were thought to play a role in the accumulation of phosphate and Ca 2+ ions in the dome cavities, which then formed crystals in the presence of organic compounds produced by lysis of cells of the deepest layers of the super-domes. The crystals of hydroxyapatite observed in standard Capan-1 cell cultures and those cocultured with fibroblasts were assumed to be a result of transepithelial transport of Ca 2+ and phosphate ions by these cells.

The Taxonomy of Carex sect. Aciculares (Cyperaceae) in South America

Carex sect. Aciculares comb. nov. comprises seven South American species and one variety and about four species in Australasia and a single species in Africa. Two new taxa, C. toroensis and C. vallis-pulchrae var. barrosiana, are described and illustrated here. Two previously unplaced species, C. minutissima and C. transandina, are also included. Plants called C. castellanosii in recent South American literature are here referred to C. vallis-pulchrae var. vallis-pulchrae. The name C. trichodes is lectotypified and a lectotype is chosen for sect. Aciculares. This section is distinguished from all others by: spike solitary, androgynous, few-flowered; scales caducous, the one or two outermost ones bract-like and fertile; perigynia erect to widely spreading at maturity but never reflexed, two veins prominent or faint and the rest obscure, apex of beak entire to bidentulate; leaves filiform, blades 1 mm wide or less, the tips mostly obtuse and cartilaginous; and plants less than 30 cm tall, growing in loose to dense clumps. All South American members of sect. Aciculares grow south of the Tropic of Capricorn, occurring in central Chile, west-central Argentina, Patagonia, Tierra del Fuego, and the Falkland Islands. Habitats are bogs and swamps, mossy margins of streams and creeks, wet borders of lakes and ponds, glacial moraines, persistently wet swales, damp depressions among tufts of grasses, moist rock crevices, rocky and sandy soil, and rock talus and scree. Carex L., with an estimated 1500-2000 species, is well represented in the southern half of South America (i.e., Argentina, Chile, Paraguay, Uru- guay, and southern Brazil), with approximately 95 species and some 30-40 infraspecific taxa in about 31 sections. Various regional floras treat- ing the sedges of this area now exist (e.g., Ange-

Inverted-V chirped phased arrays of gain-guided GaAs/GaAlAs diode lasers

Inverted-V chirped arrays of multiple quantum well GaAs/GaAlAs lasers were grown by molecular beam epitaxy. These arrays consisted of seven gain-guided lasers whose stripe widths decreased, from the central laser to the outermost ones, symmetrically. This structure makes it possible to discriminate against the higher order array supermodes, which results in diffraction limited beams with a single lobe directed perpendicular to the laser facet. Single lobed far-field patterns, 3°–4° wide, were obtained from inverted-V chirped arrays operated up to 1.5Ith. The supermode structure of these arrays was identified by studying their spectrally resolved near fields.