136,041 research outputs found
Rhagidia meyerae Halliday, 2005, sp. nov.
No full textRhagidia meyerae sp. nov. (Figs 48–54) Specimens examined Holotype female, Sedgefield, 15.vi. 1999, B. Halliday and R. Roush coll., site 99 26, capeweed and grass. Paratypes: 1 female, same data as holotype; 1 female, 1 N, Kompanjiesdrif, near Stellenbosch, 15.viii. 1994, T. K. Qin coll., site 30 2 (= 94 2) roadside grass and clover; 1 female, 54.4 km east of Cape Town, 16.viii. 1994, T. K. Qin coll., site 30 4 (= 94 4), capeweed and grass. Description Female Dorsal idiosoma (Fig. 48). Integument soft, smooth, unsclerotised. Length (including naso) 659–693 µm, width (at level of sejugal furrow) 294–357 µm (n= 4). Setal lengths (µm): internal vertical (iv) 42; external vertical (ev) 55; trichobothrium (tr) 87; scapular (sc) 79; internal humeral (ih) 32; external humeral (eh) 89; dorsal 1 (d 1) 32; dorsal 2 (d 2) 32; internal lumbar (il) 42; external lumbar (el) 21; internal sacral (ic) 66; external sacral (es) 32; trichobothrial flagellum very fine, serrated, other setae thicker, smooth to very finely serrated; serration most distinct on posterior setae; anus terminal. Ventral idiosoma (Fig. 49). Epimeral formula 3 16 3, trochanteral formula 1 12 2, all epimeral and trochanteral setae serrated, becoming slightly thicker distally (Fig. 54). Genital region with five pairs of progenital setae and five pairs of paragenital setae, all serrated and distally thickened, length of progenital lips 120 µm. Gnathosoma. Hypostome subtriangular, length ca. 70 µm, width at base ca. 87 µm, with two pairs of smooth subterminal hypostomal setae and two pairs of serrate basal hypostomal setae. Internal malae elongate, fine, smooth, external malae membranous, fringed (Fig. 49). Fixed digit of chelicera with strongly convex dorsal surface and small basal lobe, distal seta (32 µm) approximately double length of proximal seta (16 µm). Distance between bases of setae 18 µm. Movable digit crescentshaped, length 75 µm, with finely serrated inner margin (Fig. 50). Terminal segment of palp (tibiotarsus) with 10 heavily pilose setae and a short thick solenidion (Fig. 51). Legs. Rhagidial organ on tarsus I with 4 prostrate solenidia in a linear arrangement (Fig. 52), tarsus II with 3 prostrate solenidia in a linear arrangement (Fig. 53).Published as part of Halliday, R. B., 2005, Predatory mites from crops and pastures in South Africa: potential natural enemies of redlegged earth mite Halotydeus destructor (Acari: Penthaleidae), pp. 11-64 in Zootaxa 1079 on pages 52-53, DOI: 10.5281/zenodo.17035
Photoreceptor effects on plant biomass, resource allocation, and metabolic state
No full textPlants sense the light environment through an ensemble of photoreceptors. Members of the phytochrome class of light receptors are known to play a critical role in seedling establishment, and are among the best-characterized plant signaling components. Phytochromes also regulate adult plant growth; however, our knowledge of this process is rather fragmented. This study demonstrates that phytochrome controls carbon allocation and biomass production in the developing plant. Phytochrome mutants have a reduced CO2 uptake, yet overaccumulate daytime sucrose and starch. This finding suggests that even though carbon fixation is impeded, the available carbon resources are not fully used for growth during the day. Supporting this notion, phytochrome depletion alters the proportion of day:night growth. In addition, phytochrome loss leads to sizeable reductions in overall growth, dry weight, total protein levels, and the expression of CELLULOSE SYNTHASE-LIKE genes. Because cellulose and protein are major constituents of plant biomass, our data point to an important role for phytochrome in regulating these fundamental components of plant productivity. We show that phytochrome loss impacts core metabolism, leading to elevated levels of tricarboxylic acid cycle intermediates, amino acids, sugar derivatives, and notably the stress metabolites proline and raffinose. Furthermore, the already growth-retarded phytochrome mutants are less responsive to growth-inhibiting abiotic stresses and have elevated expression of stress marker genes. This coordinated response appears to divert resources from energetically costly biomass production to improve resilience. In nature, this strategymay be activated in phytochrome-disabling, vegetation-dense habitats to enhance survival in potentially resource-limiting conditions
Dawn and photoperiod sensing by phytochrome A
No full textIn plants, light receptors play a pivotal role in photoperiod sensing, enabling them to track seasonal progression. Photoperiod sensing arises from an interaction between the plant's endogenous circadian oscillator and external light cues. Here, we characterize the role of phytochrome A (phyA) in photoperiod sensing. Our metaanalysis of functional genomic datasets identified phyA as a principal regulator of morning-activated genes, specifically in short photoperiods. We demonstrate that PHYA expression is under the direct control of the PHYTOCHROME INTERACTING FACTOR transcription factors, PIF4 and PIF5. As a result, phyA protein accumulates during the night, especially in short photoperiods. At dawn, phyA activation by light results in a burst of gene expression, with consequences for physiological processes such as anthocyanin accumulation. The combination of complex regulation of PHYA transcript and the unique molecular properties of phyA protein make this pathway a sensitive detector of both dawn and photoperiod. © 2018 Proceedings of the National Academy of Sciences of the United States of America. All rights reserved
A hybrid bio-inspired system: hardware spiking neural network incorporating Hebbian learning with microprocessor based evolutionary control algorithm
No full textThe objective of the work reported in this paper was the development of an application that combined evolution and learning on a hardware platform. This was achieved on two different platforms: a COTS FPGA and a new device specifically designed for bio-inspired implementations, termed the POEtic chip. The learning process is based around a spiking neural network with Hebbian learning
Iphidozercon australis Gwiazdowicz & Halliday 2008, sp. nov.
No full textIphidozercon australis sp. nov. (Figs 1–8) Material examined. Holotype. Female. Australia, Queensland. Lab-reared 24 April 1995. Origin of culture Gadgarra Cedar, Atherton, 7 April 1995, ex fungal sporocarp, D.E. Walter coll., QM S83796, in QM, formerly in UQIC (Reg. # 91915). Paratypes. Queensland. 10 females, same data as holotype but reared 5 May 1995, UQIC Reg. #91910-91916; 2 females, 2 males, lab reared 17 December 1995, origin of culture Wright’s Creek, Lake Eacham National Park, 17º17'S, 145º37'E, 2 December 1995, ex fungi on log, D.E. Walter coll., UQIC Reg. # 91900-91902; 2 females, Cape Tribulation, Oliver Creek, 16º08'30"S 145º26'30"E, 27 June 1995, ex Asplenium nidus litter, D. Rodgers coll., UQIC # 93621, 93622; 1 female, Wongabel State Forest, 13–16 April 1994, Asplenium litter, C. Thebaud coll. (in UQIC). Description. Female. Dorsal idiosoma (Fig. 1). Dorsal shield oval, length 400 µm, width 220 µm, with distinct colliculate ornamentation throughout. All setae fine, smooth and pointed, length of setae 30 µm except j1 and three antero-lateral pairs shorter, ca. 10 µm. Ventral idiosoma (Fig. 2). Tritosternum with trapezoidal base and finely pilose laciniae, length of base 30 µm, laciniae 50 µm. Sternal shield rectangular, 80 x 40 µm, setae st1-st3 smooth and pointed, length 15 µm. Metasternal setae st4 length 15 µm. Genital shield small and narrow, length 60 µm, spatulate posteriorly. Genital setae st5 15 µm long. Anal shield obovate, length 70 µm, width 60 µm. Para-anal setae 20 µm long, postanal seta 25 µm, cribrum distinct. Stigmata located at level of coxae IV, peritremes extending anterior to coxae I, projecting for a short distance behind stigmata. Opisthogastric skin posterior to coxae IV with a pair of oval metapodal shields, a pair of smaller plates near posterior end of peritrematal shields, several pairs of very small platelets bearing pores, and 11 pairs of opisthogastric setae in addition to the R-series setae. Gnathosoma. Hypostome with robust horn-like corniculi and four pairs of setae (Fig. 3). Anterior seta h1 and palp coxal seta longest, 35 µm, internal seta h3 shorter, 25 µm, external seta h2 shortest, 20 µm. Seven transverse rows of hypostomal denticles present, number of denticles per row (anterior to posterior) 16, 10, 12, 9, 15, 15, 5. Chelicera typical for genus, fixed digit and movable digit each with three teeth (Fig. 4), other details of chelicera not visible in available specimens. Tectum with a central elongated prong ending in three denticles, lateral prongs shorter, with denticulate outer margins (Fig. 5). Palp tarsal claw with two unequal tines (Fig. 7). Legs. Lengths I 320 µm, II 260 µm, III 250 µm, IV 310 µm. Tarsus II to IV each with dorsoproximal setae ad 2 and pd 2 short and straight (Fig. 6). Setation of genua I-II-III-IV: 12-9-7-7, av 1 absent from genu II; tibiae I-II-III-IV: 12-9-7-7 (Fig. 8). Etymology. The name of this species reflects the fact that it was collected in Australia. Notes. Iphidozercon australis is similar to I. corticalis, which was described by Evans (1958) from Europe, but these two species may distinguished in several ways. The dorsal shield of I. australis is sculptured over its whole surface, while that of I. corticalis is sculptured only in the anterior half. Posterodorsal setae J, Z and S in I. australis are long, and almost reach the bases of the next posterior setae, whereas in I. corticalis they reach only half the distance to the next seta. Iphidozercon australis has two pairs of metapodal plates where I. corticalis has only one, and I. australis has a short section of peritreme behind the stigma, whereas this section of peritreme in I. corticalis is much longer. Genu II in I. australis carries nine setae, whereas in I. corticalis and the remainder of the genus there are ten setae on this segment.Published as part of Gwiazdowicz, D. J. & Halliday, R. B., 2008, The Australian species of Iphidozercon (Acari: Ascidae), pp. 47-68 in Zootaxa 1921 on pages 49-5
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Retreat of the Laurentide ice sheet tracked by the isotopic composition of Pb in western North Atlantic seawater during termination 1
No full textDuring the Last Glacial Maximum much of North America was covered by the Laurentide ice sheet. Its melting during termination 1 led to systematic changes in proglacial lake formation, continental runoff, and possibly North Atlantic Meridional Overturning Circulation. The accompanying change in chemical weathering rates in the interior of North America throughout the deglaciation resulted in a pronounced change in seawater Pb isotope composition in the western North Atlantic Ocean. Here we present the first high-resolution records of seawater Pb isotope variations of North Atlantic Deep Water extracted from authigenic Fe–Mn oxyhydroxides in three sediment cores (51GGC, 1790 m depth; 31GGC, 3410 m depth; 12JPC, 4250 m depth) from the Blake Ridge off Florida. These data reveal a striking excursion from relatively unradiogenic 206Pb/204Pb as low as 18.93 towards highly radiogenic Pb isotope compositions that was initiated during the Bølling–Allerød interstadial and was most pronounced in both intermediate and deep waters during and after the Younger Dryas (206Pb/204Pb as high as 19.38 at 8.8 ka in 4250 m). This pattern is interpreted to be a direct function of increased inflow of continent-derived radiogenic Pb into the western North Atlantic, supplied through chemical weathering of North American rocks that had been eroded and freshly exposed during the preceding glacial cycle. These sediment-derived data are complemented by new laser ablation Pb isotope data from a ferromanganese crust from the Blake Plateau at 850 m water depth, which show only small glacial–interglacial Pb isotope variations of the Florida Current (206Pb/204Pb between 19.07 and 19.16). The lack of change in the Blake Plateau record at the same time as the radiogenic excursion in the deeper sediments supports a northern origin of the pulse of radiogenic Pb. After the Younger Dryas, the deep western North Atlantic has experienced a persistent highly radiogenic Pb supply that was most pronounced during the first half of the Holocene and still lasts until today
Morphologic and functional correlates of synaptic pathology in the cathepsin D knockout mouse model of congenital neuronal ceroid lipofuscinosis
No full textMutations in the cathepsin D (CTSD) gene cause an aggressive neurodegenerative disease (congenital neuronal ceroid lipofuscinosis) that leads to early death. Recent evidence suggests that presynaptic abnormalities play a major role in the pathogenesis of CTSD deficiencies. To identify the early events that lead to synaptic alterations, we investigated synaptic ultrastructure and function in presymptomatic CTSD knockout (Ctsd) mice. Electron microscopy revealed that there were significantly greater numbers of readily releasable synaptic vesicles present in Ctsd mice than in wild-type control mice as early as postnatal day 16. The size of this synaptic vesicle pool continued to increase with disease progression in the hippocampus and thalamus of the Ctsd mice. Electrophysiology revealed a markedly decreased frequency of miniature excitatory postsynaptic currents (mEPSCs) with no effect on paired-pulse modulation of the evoked excitatory post synaptic potentials in the hippocampus of Ctsd mice. The reduced mEPSCs frequency was observed before the appearance of epilepsy or any morphologic sign of synaptic degeneration. Taken together, these data indicate that CTSD is required for normal synaptic function and that a failure in synaptic trafficking or recycling may bean early and important pathologic mechanism in Ctsd mice; these presynaptic abnormalities may initiate synaptic degeneration in advance of subsequent neuronal loss
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
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