130,545 research outputs found
Girardia clandestina Benítez-Álvarez, Sluys, Leal-Zanchet, Leria & Riutort, 2023, SP. NOV.
No full textGIRARDIA CLANDESTINA SLUYS & BENÍTEZ- ÁLVAREZ SP. NOV. Z o o b a n k r e g i s t r a t i o n: u r n: l s i d: zoobank. org:act: 6F75400B-1B3F-4B71-8351-5839C233019F Holotype: Naturalis Biodiversity Center, ZMA V.Pl. 976.4, Arroyo Sauce, near Sauce, Departamento Canelones, near Montevideo, Uruguay, 1–3 January 1987, sagittal sections on six slides. Etymology: The specific epithet is based on the Latin adjective clandestinus, secret, concealed, and alludes to the fact that it concerns a ‘hidden’ sibling species. Differential diagnosis: A species of Girardia with low triangular head with bluntly pointed tip and short, broad auricles. Dorsal body coloration variable, being of a reticulated type with darkish spots and also a pair of dark stripes, separated by a pale mid-dorsal streak or composed of a dark background interspersed with white splotches and with a pale mid-dorsal line, or variations on these two major patterns. Reproductive complex basically as in G. tigrina: the only consistent anatomical difference between the two species residing in the coat of muscles around the bursal canal. In North American G. tigrina, this coat of muscles is simple, consisting of a thin subepithelial layer of circular muscle, followed by an equally thin layer of longitudinal muscle fibres. In contrast, G. clandestina possesses a bursal canal musculature that consists of a well-developed coat of intermingled circular and longitudinal muscle fibres.Published as part of Benítez-Álvarez, Lisandra, Sluys, Ronald, Leal-Zanchet, Ana María, Leria, Laia & Riutort, Marta, 2023, First molecular phylogeny of the freshwater planarian genus Girardia (Platyhelminthes: Tricladida) unveils hidden taxonomic diversity and initiates resolution of its historical biogeography, pp. 1-19 in Zoological Journal of the Linnean Society 197 (1) on page 10, DOI: 10.1093/zoolinnean/zlac065, http://zenodo.org/record/749904
Figure 4 in Predation on invasive land gastropods by a Neotropical land planarian
No full textFigure 4. Obama ladislavii capturing Deroceras laeve: (A) planarian encountering the slug; (B) planarian attaching its anterior end to the slug; (C, D) planarian moving towards the slug's head to prevent escape; (E–H) slug surrounded by the planarian and pressed against the substrate.Published as part of Boll, Piter Kehoma & Leal-Zanchet, Ana Maria, 2014, Predation on invasive land gastropods by a Neotropical land planarian, pp. 983-994 in Journal of Natural History 49 (17) on page 989, DOI: 10.1080/00222933.2014.981312, http://zenodo.org/record/400588
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
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.
Obama tribalis Marques & Rossi & Valiati & Leal-Zanchet 2018, sp. nov.
No full textObama tribalis sp. nov. Etymology: The specific name, frOm latin tribālis (tribal), refers tO the dOrsal pigmentatiOn which resembles the crOssed stripes pattern Of the tribal style drawings. Type-material. Holotype: MZUSP PL.2140: leg. E. FederOlf, 30 June 2013, Gravataí, state Of RiO Grande dO Sul, Brazil—anteriOr tip: transverse sectiOns On 7 slides; anteriOr regiOn at the level Of the Ovaries: sagittal sectiOns On 42 slides; pre-pharyngeal regiOn: transverse sectiOns On 26 slides; cOpulatOry apparatus: sagittal sectiOns On 43 slides. Paratypes: MZU PL.00287: leg. E. FederOlf, 30 June 2013, Gravataí, state Of RiO Grande dO Sul, Brazil—anteriOr tip: transverse sectiOns On 13 slides; anteriOr regiOn at the level Of the Ovaries: sagittal sectiOns On 10 slides; pre-pharyngeal regiOn: transverse sectiOns On 4 slides; pharynx and cOpulatOry apparatus: sagittal sectiOns On 23 slides. MZU PL.00288: leg. E. FederOlf, 30 June 2013, Gravataí, state Of RiO Grande dO Sul, Brazil—cOpulatOry apparatus: hOrizOntal sectiOns On 12 slides. Diagnosis: species Of Obama with dOrsal grOund cOlOur yellOwish cOvered by irregular flecks, mOre cOncentrated laterally; pharynx cylindrical; prOstatic vesicle with twO pOrtiOns, prOximal pOrtiOn fOrked and glObOse and distal pOrtiOn funnel-shaped; penis papilla lOng, cOnical and symmetrical; male and female atria with slightly fOlded walls, and with ample cOmmunicatiOn. Molecular diagnosis: this species includes all pOpulatiOns that cluster with sequences Of specimens included in this study (GenBank accessiOn numbers MH378885–MH378886) with significant suppOrt in an adequate mOlecular delimitatiOn mOdel. Type-locality. Gravataí, RiO Grande dO Sul (RS), Brazil. Distribution: knOwn Only frOm the type-lOcality, Gravataí, RS, Brazil. Description. External features. BOdy fOliaceOus and dOrsal surface slightly cOnvex; anteriOr and pOsteriOr tips rOunded (Fig. 21). When creeping, maximum length 33 mm. After fixatiOn, maximum length 23 mm. MOuth at third-fOurth Of bOdy and gOnOpOre at pOsteriOr fOurth Of bOdy, in mOst specimens (Table 3). Live specimens with dOrsal grOund cOlOur yellOwish, cOvered by greyish pigmentatiOn in cephalic regiOn (Fig. 21). Blackish pigmentatiOn cOntOurs cephalic regiOn and cOnstitutes irregular flecks Over dOrsal surface, mOre cOncentrated laterally, sOmetimes fOrming a pattern that resembles crOssed stripes at sOme pOints (Figs. 21–23). Median regiOn Of dOrsal surface almOst withOut flecks. Paratype MZU PL. 0 0 287 with mOre abundant Overlaying black pigmentatiOn than hOlOtype (Fig. 22); paratype MZU PL. 0 0 288 with very few irregular flecks Over dOrsal surface (Fig. 21). Ventral surface greyish with yellOwish margins. After fixatiOn, dOrsal grOund cOlOur fades. Eyes, initially mOnOlObate and uniserial, surrOund anteriOr tip (Figs. 24–25). After first millimetre Of bOdy, eyes becOme larger and spread OntO dOrsal surface, Occupying maximum width Of abOut One-third Of bOdy width On either side Of bOdy. Eyes becOme trilObate after One-fifth Of bOdy length and remain dOrsal, but less numerOus tOwards pOsteriOr tip (Fig. 24). IncOnspicuOus clear halOs may Occur arOund dOrsal eyes (Fig. 26). Diameter Of pigment cups abOut 30 µm. Sensory organs, epidermis and body musculature. SensOry pits (Figs. 27–28), as simple invaginatiOns (20–40 µm deep), cOntOur anteriOr tip and Occur ventrOmarginally in irregular, single rOw in anteriOr third Of bOdy. Glands Of three types discharge thrOugh whOle epidermis Of pre-pharyngeal regiOn: rhabditOgen cells with xanthOphil secretiOn (scarcer ventrally and with smaller rhabdites), cyanOphil glands with finely granular secretiOn (Figs. 31–32) and sparser xanthOphil glands with finely granular secretiOn. Creeping sOle Occupies whOle bOdy width. Glands Of at least fOur types cOnstitute the incOnspicuOus glandular margin (Figs. 29, 30), which is nOticeable after first millimetre Of bOdy: numerOus xanthOphil glands and sparser cyanOphil glands, bOth with cOarse granular secretiOns, besides xanthOphil and cyanOphil glands with fine granules. Glands discharging thrOugh anteriOr tip Of bOdy similar tO thOse Of pre-pharyngeal regiOn (Figs. 27–28). CutaneOus musculature with usual three layers (circular, Oblique and lOngitudinal layers); lOngitudinal layer with thick bundles (Figs. 29–32). Thickness Of cutaneOus musculature twO times that Of epidermis (Table 4). Ventral musculature slightly thicker than dOrsal at sagittal plane in pre-pharyngeal regiOn (Table 4). Thickness Of cutaneOus musculature gradually diminishes tOwards bOdy margins and anteriOr tip. Mesenchymal musculature (Figs. 29, 31–32) well develOped, mainly cOmpOsed Of three layers: (1) dOrsal subcutaneOus, with decussate fibres (abOut 5–7 fibres thick), (2) supra-intestinal transverse (abOut 7–9 fibres thick) and (3) sub-intestinal transverse (abOut 7–13 fibres thick), besides fibres in variOus directiOns. Mesenchymal musculature less develOped in anteriOr regiOn than in pre-pharyngeal regiOn (Fig. 27). Pharynx. Pharynx cylindrical, nearly 7% Of bOdy length, Occupies mOst Of the pharyngeal pOuch (Fig. 33). Pharyngeal insertiOns almOst at same transversal level. MOuth lOcated clOse tO end Of pharyngeal pOuch (Fig. 33). OesOphagus shOrt, with fOlded walls. OesOphagus: pharynx ratiO 11–13%. Reproductive organs. Testes in three irregular rOws On either side Of bOdy, lOcated beneath dOrsal transverse mesenchymal muscles, between intestinal branches (Figs. 29, 31), begin slightly anteriOrly tO Ovaries, in anteriOr third Of bOdy, and extend tO near rOOt Of pharynx (Table 3). Sperm ducts dOrsal tO OvOvitelline ducts, under Or amOng fibres Of sub-intestinal transverse mesenchymal musculature, in pre-pharyngeal regiOn (Fig. 32). Spermiducal vesicles, lOcated pOsteriOrly tO pharynx, enter laterally intO prOximal pOrtiOn Of prOstatic vesicle (Figs. 35–36). PrOstatic vesicle, extrabulbar, lOcated near cOmmOn muscle cOat, with twO pOrtiOns. PrOximal pOrtiOn fOrked and glObOse (Figs. 36, 38–39), being clOser tO ventral epidermis than tO dOrsal epidermis (hOlOtype and paratype MZU PL. 00288) Or equally distant tO bOth epidermis (paratype MZU PL. 00287). Distal pOrtiOn pear-shaped (Figs. 35–36). EjaculatOry duct almOst straight, Opening at tip Of penis papilla (Figs. 35–36, 40). Male atrium with slightly fOlded walls. Penis papilla lOng (Table 3), cOnical and symmetrical, sOmetimes prOjecting intO distal pOrtiOn Of female atrium (Figs. 35–38, 40). Glands Opening intO the prOstatic vesicle Of twO types: abundant glands with amOrphOus cyanOphil secretiOn and scarcer glands with finely granular erythrOphil secretiOn (Figs. 38–39); thOse Opening intO ejaculatOry duct with amOrphOus cyanOphil secretiOn. Glands Opening thrOugh the penis papilla and epithelial lining Of male atrium Of three types. Abundant glands with finely granular erythrOphil secretiOn, as well as glands with amOrphOus cyanOphil secretiOn (Figs. 37–40), besides a third type Of gland with xanthOphil secretiOn. The latter usually is finely granular, but changes tO a cOarse granular secretiOn when Opens clOse tO the dOrsal insertiOn Of penis papilla. Muscularis Of the penis papilla and male atrium mainly cOmprised Of circular fibres mixed with sOme lOngitudinal fibres. Vitelline fOllicles (Figs. 29, 31–32, 34) well develOped in all specimens analysed, situated between intestinal branches. Ovaries Oval-elOngate, apprOximately three times lOnger than wide (0.2 mm in its lateral axis), dOrsal tO ventral nerve plate, in anteriOr fOurth Of bOdy (Fig. 34, Table 3). OvOvitelline ducts emerge dOrsally frOm median third Of Ovaries (Fig. 34) and run pOsteriOrly abOve nerve plate, amOng fibres Of sub-intestinal transverse mesenchymal musculature (Fig. 32). Ascending pOrtiOn Of OvOvitelline ducts lOcated lateral tO female atrium (Fig. 35). COmmOn glandular OvOvitelline duct shOrt, lOcated dOrsally tO pOsteriOr third Of female atrium (Figs. 35–37, 41). Female genital duct dOrsO-anteriOrly curved. Female atrium OvOid, shOwing fOlds that narrOw its lumen (Figs. 37, 41), almOst as lOng as male atrium, excepting in paratype MZU PL. 0 0 288 (Table 3). COmmOn muscle cOat pOOrly develOped, with circular, lOngitudinal and Oblique fibres, thicker arOund male atrium than arOund female atrium. Male and female atria with ample cOmmunicatiOn, withOut separating fOlds (Figs. 35–38). GOnOduct vertical at sagittal plane (Figs. 35, 37). Molecular results and phylogenetic analyses. The results frOm the cOmparisOn Of species Of Obama, including sequences dOwnlOaded frOm NCBI, shOwed that the genetic distances are highly divergent amOng specimens. In general, the mean intraspecific variatiOns ranged frOm 0% tO 2.1%, except fOr O. braunsi (2.8%), O. baptistae (4.3%), O. carinata (6.5%) and O. eudoximariae (8.7%). Meanwhile, the mean interspecific divergences vary between> 6% tO 90% and P> 0.95), recOvering the mOnOphyly fOr the currently recOgnized species Of Obama herein analysed (Figs. 42, 43). All phylOgenetic analyses shOwed a sister relatiOnship between bOth new species herein described and O. maculipunctata, which Occurs in areas Of Araucaria FOrest in sOuthern Brazil (ROssi et al. 2015). Accession numbers in GenBank: A (MH378881, MH378882, MH378883, MH37888); B (MH378885, MH378886); C (KP962485.1, KP962481.1, KP962488.1, KP962480.1, KP962454.1, KP962459.1, KP962449.1, KP962448.1, KP962452.1); D (KP962377.1, KP962378.1, KP962354.1, KP962356.1, KP962355.1, KP962373.1, KP962371.1);); E (KT250622.1, KT250623.1); F (KU564135.1, KU564134.1, KU564133.1); G (KU564157.1, KU564214.1); H (KU564163.1, KU564161.1); I (KU564149.1, KU564147.1, KU564145.1, KU564140.1, KU564148.1, KU564138.1, KU564146.1, KU564151.1); J (KU564119.1, KU564118.1); L (KU56413.1, KU56413.1, KU56413.1, KU56412.1); M (KU564152.1); N (KU564126.1); O (KU56415.1, KU564213.1); P (KU564159.1); Q (KT932833.1, KT932832.1); R (KC608318.1, KC608317.1); S (KC60825.1, KC60826.1); T (KP962391.1, KP962387.1, KP962386.1, KP962385.1, KP962390.1); U (KC608246.1, KC608254.1); V (KC608323.1, KC608324.1); W (KM053223.1, KM053214.1; KT714108.1, KT714107.1); X (KC608307.1, KC608304.1); Y (KT250629.1, KT250626.1). * Only one specimen. Notes on ecology and distribution. During inventOries Of land flatwOrms in areas Of Araucaria mOist fOrest lOcated in the states Of Paraná and Santa Catarina, in sOuth Brazil, Obama allandra was fOund Only in its typelOcality, the Araucaria Natural Heritage Private Reserve, state Of Paraná, in a site shOwing an initial stage Of regeneratiOn with pOOrly develOped understOrey (ROssi & Leal-Zanchet 2017). The species shOwed mOderate abundance during bOth day and night samplings between May 2014 and July 2015. Obama tribalis Occurs in an unprOtected, private area belOnging tO an urban envirOnment, lOcated abOut 500km sOuth frOm the type-lOcality Of O. allandra, at the nOrtheast hillside Of RiO Grande dO Sul (sOuthern Brazil). Specimens Of O. tribalis were cOllected during OccasiOnal samplings, withOut standardized effOrt. The vegetatiOn Of the type-lOcality Of O. tribalis is a secOndary fOrest that represents a remnant Of the Original fOrest (semi-deciduOus fOrest), which cOvered the metrOpOlitan regiOn Of POrtO Alegre.Published as part of Marques, Alessandro, Rossi, Ilana, Valiati, Victor Hugo & Leal-Zanchet, Ana Maria, 2018, Integrative approach reveals two new species of Obama (Platyhelminthes: Tricladida) from the South-Brazilian Atlantic Forest, pp. 99-126 in Zootaxa 4455 (1) on pages 108-119, DOI: 10.11646/zootaxa.4455.1.4, http://zenodo.org/record/145699
Quantum Dots: Synthesis and Characterization
No full textSemiconductor nanocrystals, also known as quantum dots (QDs), are among the nanoscale materials that have been most investigated in the last two decades. This article concentrates on the synthesis of QDs prepared via chemical approaches in the liquid phase. Solution synthesis techniques of QDs started with pioneering work on II-VI semiconductors and have been rapidly extended to most of the III-V, IV-VI, and group IV compounds, to various metals, alloys, metal oxides, and even to doped nanocrystals. Parallel to synthesis techniques, many characterization tools are now available for QDs, of which we will give an overview in this article
Structure Population In Thioi-passivated Gold Nanoparticles
No full textChemically synthesized nanoparticles can be regarded as building blocks for more complex systems. Hence, the characterization of their attributes is a key step toward controlling and tuning the properties of new nanocomposite materials. We present a structural characterization of thiol-capped gold nanoparticles as a function of size (2-4 nm) by X-ray diffraction (XRD). In addition to the fee bulk structure, nanometric gold may present decahedral or icosahedral structures depending on particle size. To evaluate the structure evolution, we have applied Debye function analysis to the XRD profiles. The analysis reveals a high proportion of defective and complex structures in all samples, which may have become trapped by the growth conditions. Nevertheless, the fee structure is more prominent with increasing diameter, indicating that thermodynamics also plays an important role in the average structure of this system. The results underline the importance of performing careful structural characterization of chemically synthesized nanoparticles, in particular, in systems such as gold, where several distinct and stable structures are known to have little difference in energy. © 2000 American Chemical Society.104471101311018Alivisatos, A.P., Barbara, P.F., Castleman, A.W., Chang, J., Dixon, D.A., Klein, M.L., McLendon, G.L., Ratner, M.A., (1998) Adv. Mater., 10, p. 1297. , and references thereinPen, X., Wickham, J., Alivisatos, A.P., (1998) J. Am. Chem. Soc., 120, p. 5343Alvarez, M.M., Khoury, J.T., Schaaff, T.G., Stifanafigullin, M., Vezmar, L., Whetten, R.L., (1997) J. Phys. Chem. B., 707, p. 3706Sun, S.H., Murray, C.B., Weller, D., Folks, L., Moser, A., (2000) Science, 287, p. 1989Bucher, J.P., Douglas, D.C., Blomfield, L.A., (1991) Phys. Rev. Lett., 66, p. 3052Lisiecki, I., Filankembo, A., Sack-Kongehl, H., Weiss, K., Pileni, M.P., Urban, J., (2000) Phys. Rev. B, 61, p. 4968Peng, X., Manna, L., Yang, W., Wickham, J., Scher, E., Kadavanich, A., Alivisatos, A.P., (2000) Nature, 404, p. 59Ino, S., (1969) J. Phys. Soc. Jpn., 26, p. 1559Ino, S., (1969) J. Phys. Soc.'Jpn., 27, p. 941Flueli, M., (1989) Observation des Structures Anormales de Petites Particules d'Or et_d'Argent par Microscopic Eletronique AHaute Resolution et Diffraction d'Electrons par un Jet d'Agregats d'Argent, , These No 769, Ecole Polytechnique Federale de Lausanne, SwitzerlandMalm, J.-O., O'Keefe, M.A., (1997) Ullramicroscopy, 68, p. 13Brust, M., Walker, M., Bethell, D., Schiffrin, D.J., Whyman, R., (1994) J. Chem. Soc., Chem. Commun., p. 801Brust, M., Bethell, D., Schiffrin, D.J., Kiely, C.J., (1995) Adv. Mater., 7, p. 795Zanchet, D., Tolentino, H., Martins Alves, M.C., Alves, O.L., Ugarte, D., (2000) Chem. Phys. Lett., 323, p. 167Cusatis, C., Franco, M.K., Kakuno, E., Giles, C., Morelhao, S., Mello, V., Mazzaro, I., (1998) J. Synchrotron Rad., 5, p. 491Marks, L.D., (1994) Rep. Prog. Phys., 57, p. 603Zanchet, D., Hall, B.D., Ugarte, D., (1999) Characterization of Nanophase Materials, , Wang, Z. L., Ed.VCH-Wiley: WeinheimHall, B.D., (2000) J. Appl. Phys., 87, p. 1666Hall, B.D., Flüeli, M., Monot, R., Borel, J.-P., (1989) Z Phys. D, 12, p. 97Hall, B.D., Flüeli, M., Monot, R., Borel, J.-P., (1991) Phys. Rev. B, 43, p. 3906Reinhard, D., Hall, B.D., Ugarte, D., Monot, R., (1997) Phys. Rev. B, 55, p. 7868Gnutzmann, V., Vogel, W., (1990) /. Phys. Chem., 94, p. 4991Vogel, W., Cunningham, D.A.H., Tanaka, K., Haruta, M., (1996) Catal. Lett., 40, p. 175Guinier, A., (1994) X-ray Diffraction in Crystals, Imperfect Crystals, and Amorphous Bodies, , Dover: New YorkHall, B.D., Zanchet, D., Ugarte, D.J., Appl. Crystallogr, , Accepted for publicationVogel, W., Bradley, J., Vollmer, O., Abraham, I., (1998) J. Phys. Chem. B, 102, p. 10853Van De Waal, B., (1996) Phys. Rev. Lett., 76, p. 1083Cleveland, C.L., Landman, U., Schaaff, T.G., Shafigullin, M.N., Stephens, P.W., Whetten, R.L., (1997) Phys. Rev. Lett., 79, p. 1873Sun, S., Murray, C.B., (1999) /. Appl. Phys., 85, p. 4325Dinega, D.P., Bawendi, M.G., (1999) Angew. Chem., Int. Ed., 38, p. 1788Hosteller, M.J., Wingate, J.E., Zhong, C.J., Harris, J.E., Vachet, R.W., Clark, M.R., Londono, J.D., Murray, R.W., (1998) Langmuir, 14, p. 1
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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