1,721,562 research outputs found
Vosmaeria Fristedt 1885
No full textVosmaeria Fristedt, 1885 Synonymy: Vosmaeria Fristedt, 1885: 24. Type species: Vosmaeria crustacea Fristedt, 1885 (by monotypy). Diagnosis (here emended): Thinly encrusting sponges. Surface smooth with thin papillae. Oscula on apices of the papillae, ostia perforate the papillae walls. Choanosomal skeleton composed by principal tracts of (sub)tylostyles running from the sponge base to the surface and forming the papillae skeleton. Free (sub)tylostyles and oxeas scattered in the choanosome between the principal tracts. Ectosomal skeleton dense and firm, constituted mainly by tangentially oriented intercrossing oxeas.Published as part of Gerasimova, Elena, Erpenbeck, Dirk & Plotkin, Alexander, 2008, Vosmaeria Fristedt, 1885 (Porifera, Demospongiae, Halichondriidae): revision of species, phylogenetic reconstruction and evidence for split, pp. 1-37 in Zootaxa 1694 on page 5, DOI: 10.5281/zenodo.18067
Tetilla sibirica Fristedt 1887
No full textTetilla sibirica Fristedt, 1887 Figure 6; Table 6 Synonymy: Tethya sibirica Fristedt, 1887: 436 –437 pl. 28, fig. 17. Tetilla sibirica: Koltun 1966: 61 –62, fig. 32–33. Morozov et al. 2019: 21 –22, fig. 12. Dinn & Leys 2018: 86. Material examined. CMNI 2018-0165, specimen in 95% ethanol, collected by Philippe Archambault by ROV hydraulic manipulator; 25 October 2015, 65 m depth, (63° 38.5745’N, 68° 36.5265’W). CMNI 2018-0183, specimen in 95% ethanol, collected by Curtis Dinn by Agassiz trawl; July 15, 2017, 141 m depth, (63° 38.390’N, 68° 37.642’W). All operations performed from the CCGS Amundsen near Hill Island in Frobisher Bay. Description. Two specimens of different sizes were collected in the inner bay near Hill Island. CMNI 2018- 0 165 (Fig. 6B) is a large spherical sponge about 20 cm in diameter in situ (Fig. 6A), and the root is nearly 13 cm long after collection, and CMNI 2018-0183(Fig. 6D) is less spherical and more club shaped, about 2 cm in width, 3.5 cm in height with a root length of 2.5 cm. The surface of both specimens is hispid due to protruding spicules. The sponges are firm and incompressible, are covered in sediment in situ, and appear light brown or grey immediately after collection. (Fig. 6B, D). The spicules from CMNI 2018-0183 consist of large oxeas 2811 (1784– 4080) x 37 (28–54) µm; short oxeas 1026 (754–1290) x 40 (26–52) µm; anatriaenes 3030 (1992–4378) x 21 (9–35) µm; protriaenes, sometimes with one whip-like clad 2219 (1150–3452) x 21 (6–29) µm, clads are 57 (29–83) µm, whip-like clads, when present are 91 (64–113) µm; and sigmaspires 17 (11–20) µm in length (Fig. 6 E–K). Genetic data. 28S rDNA sequences suggest this specimen groups with Cinachyra and Antarctotetilla specimens based on the D3–D5 domain sequence (GenBank accession MH394249). This species and the sympatric C. polyura appear to be closely related based 28S sequences. Taxonomic Remarks. The original description by Fristedt (1887) is of a firm sponge that is ovoid or subspherical with numerous roots. Koltun (1966) gives the same description. Fristedt (1887) does not specify a range of spicule lengths, and does not provide widths, yet the lengths reported largely agree with the measurements given by Koltun (1966) (Table 6). Fristedt does not distinguish between protriaenes with or without whip-like clads. In CMNI 2018-0165, protriaenes with clads of similar lengths were rare, therefore both regular protrienes and those with whip-like clads are treated as similar spicules here. Fristedt (1887) described the sigmaspires as smooth sigmas (“sigmoid bihamate spicules”) in comparison to the “knotty” sigmaspires found in Craniella polyura (T. polyura in Fristedt, 1887 and Koltun, 1966). Koltun (1966) shows sigmaspires which appear smooth in his illustration, but they differ from the sigmaspires of C. polyura, as they do not possess a centrotylote swelling. The sigmaspires from the Frobisher Bay specimens are entirely spined with fine teeth, an aspect that is not always apparent from light micrographs. Micrographs of C. polyura (described as T. polyura, Van Soest 2016) show the centrotylote swelling clearly, which the sigmaspires in these specimens lack. Since the spicules match the descriptions by Fristedt and Koltun, and lack sigmaspires with central swellings, this sponge is considered to be T. sibirica. 1 Koltun, 1966 describes regular protriaenes without a whip like clad to be 2000–3700 in length x 6–12 in width with clads of 70–150 µm. The protriene types in CMNI 2018-0183 were treated as one, as the shaft length did not appear different between the two types. Discussion. This is the first record of T. sibirica in the Northern Labrador marine ecoregion. The World Porifera Database suggests that the species has a circumpolar high Arctic distribution and is also found in the Barents Sea and coastal Northern Russia in the Laptev Sea. Koltun (1966) suggests that the species even occurs off the Pacific coast of the Kuril Islands. The sponge is also suggested to occur in James Bay and SE Hudson Bay (Stewart & Lockhart 2005), but source material is not listed or available for taxonomic assessment and so those identifications cannot be presently confirmed. This is a shallow water species. The specimens in this study were found at 65 m and 141 m, whereas Koltun (1966) found it at depths of 7–54 m in the Arctic and 127–414 m in the Pacific Ocean. In Frobisher Bay, this sponge is quite common on sandy substrates at the site near Hill Island. In ROV video transects the sponge is seen growing amongst solitary tunicates near the gardens formed by Iophon koltuni, and in areas with few other sponges growing nearby. Both the large and small specimens have small tube worms attached to the base and embedded in the distal portions of the sponge. It is common to see echinoderms on the surface of the sponge. Brittle stars are often attached to the surface, and large crinoids are often perched near the osculum (Fig. 6 A, C).Published as part of Dinn, Curtis, Edinger, Evan & Leys, Sally P., 2019, Sponge (Porifera) fauna of Frobisher Bay, Baffin Island, Canada with the description of an Iophon rich sponge garden, pp. 301-325 in Zootaxa 4576 (2) on pages 315-317, DOI: 10.11646/zootaxa.4576.2.5, http://zenodo.org/record/262495
Bernoulli One-Armed Bandits--Arbitrary Discount Sequnces
No full text1 online resource (PDF, 33 pages)Berry, Donald A.; Fristedt, Bert. (1976). Bernoulli One-Armed Bandits--Arbitrary Discount Sequnces. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/199265
Two Armed Bandits with a Goal: II: Dependent Arms
Full text link1 online resource (PDF, 27 pages)Berry, Donald A.; Fristedt, Bert. (1979). Two Armed Bandits with a Goal: II: Dependent Arms. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/199358
Maximizing the Length of a Success Run for Many-Armed Bandits
Full text link1 online resource (PDF, 16 pages)Berry, Donald A.; Fristedt, Bert. (1981). Maximizing the Length of a Success Run for Many-Armed Bandits. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/199383
Two-Armed Bandits With a Goal: I: One Arm Known
No full text1 online resource (PDF, 39 pages)Berry, Donald A.; Fristedt, Bert. (1979). Two-Armed Bandits With a Goal: I: One Arm Known. Retrieved from the University Digital Conservancy, https://hdl.handle.net/11299/199346
Minska isoleringen på äldreboenden med surfplattor och digitala ombud
No full textI en svår tid kan ett enkelt digitalt upplägg innebära både glädje och lättnad för många människor. Det skriver forskarna Tove Harnett, Sofi Fristedt och Håkan Jönson tillsammans med Eva Wiman, anhörigrådgivare och verksamhetsansvarig vid Malmö anhörigförening
Vosmaeria crustacea Fristedt 1885
No full textVosmaeria crustacea Fristedt, 1885 Synonymy: Vosmaeria crustacea – Fristedt, 1885: 24, pl. II figs. 5 a–d; Rezvoj, 1928: 81; Burton, 1930: 496; Arndt, 1935: 37, fig. 60; Alander, 1942: 76; Koltun, 1966: 91, pl. XXIV figs. 5–6, text-fig. 62.; Erpenbeck & van Soest, 2002: 815, figs. 18 d–g. Inflatella ? sp. – Vosmaer, 1885: 21, pl. 5 figs. 17–19. Inflatella crustacea – Levinsen, 1893: 414. Vosmaeria robusta – Swarczewsky, 1906: 320, pl. 14. Inflatella robusta – Breitfuss, 1911: 219. Type material: Type series identified by Fristedt (1885) was collected near Bohuslän, western Swedish Coast (Skagerrak Straight, North Sea). Fristedt did not designate a holotype. SMNH Type N 1686 a (fig. 1 A) is here designated as the lectotype because it was collected by Fristedt himself and the locality written on the original label (Bohuslän, Gullmaren) corresponds to the information given in his publication. The remaining four specimens (figs. 1 B-E) and one fragment in the type series are designated as paralectotypes. Lectotype (here designated): SMNH Type N 1686 a (dry specimen): Bohuslän, Gullmaren; 54–125 m; date unknown; collector K. Fristedt. Paralectotypes: SMNH Type NN 1686 b,c (1 whole dry specimen and 1 small dry fragment, respectively): same locality as lectotype. SMNH Type N 1198 a,b (2 specimens in alcohol): Bohuslän, Gullmarsfjord, Kristineberg; depth unknown; 1879; collector H. Theel. SMNH Type N 1208 (1 specimen in alcohol): Bohuslän; depth unknown; 1876; collector K. Fristedt. Additional material used for morphological studies (all fixed in 70 % alcohol): Murman Coast, Barents Sea: ZIRAS N 35 a (1 specimen): Kildin Straight; 100 m; bottom–shells, silted sand, stones; 25.07.1884; Expedition of Herzenstein; st. 66. ZIRAS N 36 a/ 5626 (1 specimen): Arsky Bay; depth unknown; bottom–stones, silt; 26.06.1884; Expedition of Herzenstein; st. 50. ZIRAS N 77 / 5624 (1 specimen): 69 ° 22 ' N – 32 ° 56 ' E; 210 – 270 m; bottom–silt; 23.08.1900; r/v ‘St. Andrew Pervozvanny’; st. 312; Petersen trawl N 718. ZIRAS N 81 (1 specimen): Kola Bay; depth unknown; 7.08.1913; collector K.M. Derjugin. ZIRAS N 85 a/ 5627 (1 specimen): 69 ° 45 ' N – 31 ° 09.5' E; 71 m; bottom–stones; 16.08.1900; r/v ‘St. Andrew Pervozvanny’; st. 307; dredge N 710. ZIRAS N 89 (1 specimen): Motka Bay; 60–100 m; date unknown; collector Jarzhinsky. Kandalaksha Bay, White Sea: ZIRAS N 1 / 20968 (1 specimen): 66 ° 52.7 ' N – 32 ° 30 ' E; 18 m; bottom– sand, gravel; 26.08.1961; r/v ‘Professor Mesyatsev’; st. 803 (9); collector Kunin. AP Por N 66 (1 specimen): Chupa Inlet, Sel'dyanaya Harbour, 66 ° 20.129 ' N – 33 ° 37.6 ' E; 15 m; bottom–silt, stones; 02.07.2001; collectors E. Gerasimova & A. Plotkin. AP Por NN 408, 409, 410, 416 (4 specimens): Keret' Inlet, Podpakhta Straight; 66 ° 18.161 ' N – 33 ° 37.896 ' E; 15–17 m; bottom–silt, pebbles; 27.07.2001; collectors E. Gerasimova & A. Plotkin. Onega Bay, White Sea: ZIRAS N 4 / 21052 (1 specimen): Cape Listvenny; 27 m; bottom–silted sand, pebbles, gravel; 29.07.1982; White Sea expedition of the Zoological Institute, Russian Academy of Sciences; transect 5, st. 2 / 2; collector Golikov. ZIRAS N 29 a (1 specimen): 65 ° 10 ' N – 35 °02.3' E; 65 m; bottom–gravel; 18.10.1964; r/v ‘Professor Mesyatsev’; st. 1155 (2); collector Kunin. ZIRAS N 32 a (1 specimen): 65 °09.8' N – 35 °02' E; 59–60 m; bottom–gravel, sand; 29.06.1961; r/v ‘Onega’; st. 2; collector Kunin. ZIRAS NN 73 a,b,c (3 specimens): precise location unknown; 43 m; bottom–pebbles; 11.07.1984; Expedition of the White Sea Biological Station of Moscow State University; st. 503 (D- 1); collector N.L. Semyonova. Material used for molecular analysis (all fixed in 96 % alcohol): Kandalaksha Bay, White Sea: AP Por N 339 (2 specimens): Keret' Inlet, Sredny Island; 66 ° 17.391 ' N – 33 ° 38.025 ' E; 10–14 m; bottom–vertical rock; 1.06.2003; collectors Gerasimova & Plotkin. AP Por N 260 (5 specimens): Keret' Inlet, Podpakhta Straight; 66 ° 18,161 ' N – 33 ° 37,896 ' E; 10–20 m; bottom–ferro-manganous concretions with silt; 2.06.2003; collectors E. Gerasimova & A. Plotkin. Description: External characters Dry lectotype an encrusting, irregular shaped sponge, approx. 21 mm long, 11 mm wide, 2 mm thick (fig. 1 A). Surface light brown, smooth, with 22 cone-like sharply pointed white papillae, 2–4 mm long, about 1 mm in basal diameter. The largest examined specimens up to 5.5 cm 2 in square with more than 80 papillae (fig. 1 F). Mean concentration of papillae 15 ± 1 per cm 2 of surface. Surface of living specimens usually brown due to the agglutinated sediments and often covered by foraminiferans. Ectosome firm and dense, hardly detachable from choanosome. The latter faintly beige. Papillae whitish and semitransparent, 0.5–8 mm in height, 0.1–1.2 mm in basal diameter. Discrimination between inhalant and exhalant papillae impossible by a naked eye, or under low magnification. Skeleton Choanosomal skeleton constituted by dense tracts of (sub)tylostyles (140–300 µm thick) running from the sponge base through the choanosome, and forming the sheath framework of the papillae (fig. 2 A). Free tylostyles and oxeas randomly scattered between the principal tracts. Skeleton of the sponge base consists of a dense, confused spicule mass (fig. 2 B). Ectosomal skeleton very firm, 300–600 µm in thick, constituted mainly by oxeas and a smaller amount of tylostyles lying tangentially to the surface (fig. 2 C). Ectosomal areas close to the papillae contain also oxea-derived styles. Aquiferous system Walls of inhalant papillae perforated by ostia mainly in their apical part (fig. 3 A). Ostia 5–11 µm in diameter, connected by short transversal canals, and with a central inhalant canal (diameter from 20–40 µm at the upper part of the papilla, up to 200–350 µm in its base). The latter branches beneath the ectosome into several thinner canals, running into the choanosomal inhalant aquiferous cavities, from which the water flows to the choanocyte chambers (20–35 µm in diameter) along numerous canals. The exhalant canals run from the choanocyte chambers to the large choanosomal exhalant atriums, opening in the single central canal of the exhalant papilla (fig. 3 B), which terminates in an osculum. The diameter of the central exhalant canal varies from 250–500 µm at the papilla base, to 50–230 µm at its upper part. Spicules (means in parentheses) -(Sub)tylostyles (fig. 4): Altogether, 720 tylostyles observed (30 spicules in each specimen). In the lectotype all observed tylostyles with both tips rounded, and the tyles usually well developed and moderately displaced from the proximal tips of spicules (table 2). Two spicules had one additional tyle. Most tylostyles slender and slightly curved. Measurements (table 3): length 610–955 µm (809 µm), proximal diameter 7.5– 17.5 µm (13.8 µm), diameter of tyle 12.5–18.8 µm (16.4 µm), central diameter 7.5–20 µm (14.1 µm), distal diameter 2.5–7.5 µm (5 µm). In other specimens: 63 % of all observed tylostyles slender and 37 % fusiform; more than 73 % straight, about 22 % slightly curved, 4 % moderately curved and approx. 1 % considerably curved; near 99 % with both tips rounded and about 1 % with acerate distal tips; 95 % with well developed tyles, less than 5 % with weakly developed tyles and 0.3 % have no tyle: approx. 13 % with terminal tyles, 46 % with slightly displaced tyles, 29 % with moderately displaced tyles and about 11 % with considerably displaced tyles; about 1.5 % with one additional tyle and 0.6 % with two additional tyles (table 2). Measurements (table 3): length 260–1130 µm (688 µm), proximal diameter 3.8–23.3 µm (12.7 µm), diameter of tyle 7.5–28.3 µm (15.7 µm), central diameter 3.8–26.7 µm (13.8 µm), distal diameter 0–15 µm (4.9 µm). Tylostyles cannot be divided into separate size classes as their frequency distribution is close to normal (fig. 6 A). Abbreviations: Curvature: S–straight, SC–slightly curved, MC–moderately curved, CC–considerably curved; Slenderness: F–fusiform, SL–slender; Tyle development: A–absent, WK–weakly developed, WL–well developed; Tyle location: T–terminal, SD–slightly displaced, MD–moderately displaced, CD–considerably displaced. (Sub)tylostyles Oxeas Curvature Slender- Tyle develop- Tyle location Curvature ness ment -Oxeas (figs. 5 A–C; E–F): Altogether, 720 oxeas observed (30 spicules in each specimen). In the lectotype all oxeas with acerate tips, most slightly curved (table 2). Measurements (table 3): length 610–1010 µm (815 µm), central diameter 17.5–32.5 µm (24.3 µm). In other examined specimens: most oxeas with acerate tips (fig. 5 A–B; E) and very few with blunt tips (fig. 5 C; F); majority smooth, while 1,1% centrotylote; about 17 % of all observed oxeas straight, 68 % slightly curved, 14 % moderately curved and less than 1 % considerably curved (table 2). Measurements (table 3): length 340–1100 µm (690 µm), central diameter 7.5–50 µm (23.5 µm). Oxeas cannot be divided into separate size classes as their frequency distribution is close to normal (fig. 6 B). -Oxea-derived styles (fig. 5 D): Altogether, 129 styles observed. No styles found in the specimens SMNH Type N 1686 b and ZIRAS N 73 b. In the lectotype two styles examined (table 3), both straight with acerate distal tips. One style fusiform, with a well developed slightly displaced tyle, length 890 µm, 15 µm in proximal diameter, 16.3 µm in central diameter. The other style slender, with no tyle, length 630 µm, 25 µm in both diameters. In other examined specimens: 67 % of all observed styles fusiform and 33 % slender; 53 % straight, 36 % slightly curved and about 9 % moderately curved; majority with acerate distal tips while five styles with blunt tips; about 66 % without tyles, approx. 20 % with well developed and 14 % with weakly developed tyles. Measurements (table 3): length 230–930 µm (571 µm), proximal diameter 5–48.3 µm (17.9 µm), central diameter 7.5–48.3 µm (22.8 µm). All measurements are given in μm. Each measurement is given as minimum-mean-maximum. 30 oxeas and 30 (sub)tylostyles were measured for each specimen. Number of measured styles is given at the end of the lower row as n. Length is given in the upper row; diameter is given in the lower row. Diameter of tylostyles is given as proximal diameter / central diameter / distal diameter. Diameter of styles is given as proximal diameter / central diameter. Specimen Region (Sub)tylostyles Oxeas Oxea-derived styles SMNH Type Skagerrak 560-872 - 1060 420-883 - 1100 600-752 - 930 N 1198 a Straight 7.5-14.7 - 21.3 / 8.8-17.5 - 23.8 / 0-6.5 - 10 15-33.8 - 50 10-23.3 - 47.5 / 25-36 - 47.5 n = 5 Distribution and ecology: North Sea: Skagerrak Straight (type locality, depth 54–125 m); Barents Sea: from the Murman Coast in the South to 74 ° 50 ' N in the North (depth 32–270 m); White Sea: Kandalaksha and Onega Bays (depth 10– 120 m) (see map on fig. 9). Sponges occur mainly at sites with low hydrodynamism on plain silted bottom overgrowing small stones, pebbles, ferromanganese concretions, wood residuals, polychaete tubes and empty bivalve shells; maximum observed density 15 spec./m 2, maximum biomass 3 g /m 2. More rarely sponges grow on vertical rocks; maximum density 22 spec./m 2, maximum biomass 5 g /m 2. In both habitats sponges covered with silt with only the papillae protruding, hardly seen by a diver. Geographical variability of spicules: Spicule length demonstrated significant dependence on the region (table 4). Both tylostyles and oxeas of the White Sea sponges shorter than those of other specimens (figs. 7 A; C). No significant difference in spicule size registered between the North and Barents Sea sponges and between the specimens from the Kandalaksha and Onega Bays within the White Sea. No dependence detected of spicule shape on the geographical locality (fig. 8).Published as part of Gerasimova, Elena, Erpenbeck, Dirk & Plotkin, Alexander, 2008, Vosmaeria Fristedt, 1885 (Porifera, Demospongiae, Halichondriidae): revision of species, phylogenetic reconstruction and evidence for split, pp. 1-37 in Zootaxa 1694 on pages 6-15, DOI: 10.5281/zenodo.18067
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
- …
