544 research outputs found
The ecological dynamics of decision-making in sailing
No full textCompetitive sailing is characterised by continuous interdependencies of decisions and actions. All actions imply a permanent monitoring of the environmental conditions, such as intensity and direction of the wind, sea characteristics, and the behaviour of the opponent sailors. These constraints on sailors’ behavior are in constant change implying continuous adjustments in sailors’ actions and decisions. Among the different parts of a regatta, tactics and strategy at the start are particularly relevant. Among coaches there is an adage that says that “the start is 50% of a regatta” (Houghton, 1984; Saltonstall, 1983/1986). Olympic sailing regattas are performed with boats of the same class, by one, two or three sailors, depending on the boat class. Normally before the start, sailors visit the racing venue and analyse wind and sea characteristics, in order to fine- tune their boats accordingly. Then, five minutes before the start, sailors initiate starting procedures in order to be in a favourable position at the starting line (at the “second zero”). This position is selected during the start period according to wind shifts tendencies and the actions of other boats (Figure 11.1). Only after the start signal can the boats cross the imaginary starting line between the race committee signal boat “A” and the pin end boat. The start takes place against the wind (upwind), and the boats start racing in the direction of mark 1. Based on the evaluation of the sea and wind characteristics (e.g. if the wind is stronger at a particular place on the course), sailors re- adjust their strategy for the regatta. This strategy may change during the regatta, according to wind changes and adversary actions. More to the point, strategic decisions constrain and are constrained by on- line decisions during the regatta
Novel taxa of Cheilostomata Bryozoa discovered in the historical backlogs of the Iziko South African Museum
No full textBoonzaaier-Davids, Melissa K., Florence, Wayne K., Gibbons, Mark J. (2020): Novel taxa of Cheilostomata Bryozoa discovered in the historical backlogs of the Iziko South African Museum. Zootaxa 4820 (1): 105-133, DOI: https://doi.org/10.11646/zootaxa.4820.1.
BRICS in Africa: promoting development
No full textSummary of the discussion held at the book launch at Exclusive Books, V&A Waterfront, 11 OctoberAn enlightening book launch was held at Exclusive Books in the V&A Waterfront, featuring a distinguished panel including the book's co-editors Krish Chetty, Dr. Yul Derek Davids, and contributing
author Dr. Jaya Josie. The event centred around their new book, which delves into the intricate
dynamics of BRICS (Brazil, Russia, India, China, and South Africa) nations and their influence on African
development.N/
Online Payment Mechanisms in the Chinese Domestic Economy
No full textThe purpose of this document is, based on the different kinds of electronic payments mechanism and the above-mentioned features of Internet payment instruments, to provide a brief background to the rapid emergence of methods, which use electronic means to transfer value, or to facilitate the transfer of value
Khulisa carolinae Boonzaaier-Davids & Florence & Gibbons 2020, n. sp.
No full textKhulisa carolinae n. sp. (Fig. 6 A–F, Table 5) zoobank.org/ 5B434129-D151-4297-AB70-13ED3170188C Material examined. Holotype: SAMC-A029002 (in ethanol), station TRA 31 (34°49’S, 20°21.5’E), off Arniston, South Coast, South Africa, UCT Ecological Survey, trawl, depth 86 m, 9 September 1947. Additional material: SAMC-A 077262 (in ethanol), FAL 330. Additional comparative material: Cribrilina simplex, NHMUK 1963.3.20.2 (part of type), No. 27G, Still Bay, South Coast, South Africa, UCT Ecological Survey, 5 January 1932, no additional information. Cribrilaria africana, NHMUK 1983.11.5.75 (paratype), station SM 164 (33°04.6’S, 28°06.6’E), off East London, Southeast Coast, South Africa, RV Meiring Naude Survey, heavy dredge, depth 90 m, 26 May 1978. Cribrilaria innominata, SAMC-A 026567, station SM 163 (33°04.6’S, 28°06.6’E), off East London, Southeast Coast, South Africa, heavy dredge, depth 90 m, 26 May 1978. Etymology. Named after the first author’s grandmother, ‘Ouma’ Caroline Keet (née Abrahams) (b. 1933). She deeply invested in her children’s education during the difficult circumstances of the ‘Apartheid’ Era; the strong role she plays in her family is hereby acknowledged. Diagnosis. See genus. Description. Colony encrusting; colour creamy white and translucent in ethanol preserved material. Zooids closely juxtaposed with vertical walls directly abutting each other. Autozooid elliptical to subrectangular, about 0.66 mm long by 0.42 mm wide; frontal shield composed of seven to ten pairs of costae, flat to slightly convex, gymnocystal margin extremely reduced; three to four rounded intercostal lacunae aligned in rows on each side, fused completely along the mid-line where tips of the costae meet, sometimes forming an additional small lacuna. Orifice wider than long, deep semicircular, smooth edged; a thick, overarching apertural bar obscuring the primary orifice; secondary orifice with a U-shaped pseudo-sinus (V-shaped in giant dimorphic zooids) formed by a pair of projections close to the midline of the costae forming the apertural bar. Dimorphic zooids interpreted as brooding zooids, same shape and structure as ordinary autozooids but larger, about 1.27 mm long by 0.69 mm wide (N T = 1), scattered throughout the colony; three to nine rounded intercostal lacunae on each side. Interzooidal avicularia spatulate, about 0.52 mm long by 0.18 mm wide (N T = 2), scattered throughout the colony; rostrum raised and cup-like. Interzooidal communication through uniporous mural septula. No apparent ovicells or ooecia, brooding presumably taking place in dimorphic zooids. Ancestrula not observed. Remarks. Three known species of Cribrilinidae were previously described from South Africa: Cribrilina simplex O’Donoghue & de Watteville, 1935, C. dispersa O’Donoghue & de Watteville, 1937, and Cribrilaria africana Hayward & Cook, 1983. The widespread C. innominata (Couch, 1844) has also been reported from this region (Hayward & Cook 1983). Khulisa carolinae n. gen. et n. sp. differs in several features from all the above-mentioned species (see also Remarks for the genus). Khulisa carolinae n. gen et n. sp. forms encrusting patches on hard substrata including bryozoans, for example Reteporella sp. It was sampled near Arniston and False Bay, east of Smitswinkel Bay, on the South Coast, at 51–86 m depth.Published as part of Boonzaaier-Davids, Melissa K., Florence, Wayne K. & Gibbons, Mark J., 2020, Novel taxa of Cheilostomata Bryozoa discovered in the historical backlogs of the Iziko South African Museum, pp. 105-133 in Zootaxa 4820 (1) on pages 116-118, DOI: 10.11646/zootaxa.4820.1.5, http://zenodo.org/record/439737
FIGURE 9. A–F. Phidolopora chakra n in Novel taxa of Cheilostomata Bryozoa discovered in the historical backlogs of the Iziko South African Museum
No full textFIGURE 9. A–F. Phidolopora chakra n. sp. (SAMC-A029097) A. Partial view of a colony fragment showing ovicelled zooids and fenestrulae (scale bar = 0.4 mm, magnified x50). B. Abfrontal view of a colony fragment showing conspicuous vibices and two types of adventitious avicularia (scale bar = 0.2 mm, magnified x75). C. Close-up of an ovicell and avicularia (scale bar = 0.1 mm, magnified x200). D. Close-up of the orifice with beaded anter and shallow sinus (scale bar = 0.05 mm, magnified x500). E. Developing ooecium (scale bar = 0.1 mm, magnified x200). F. Close-up of ovicells with median convexity and secondary calcification (scale bar = 0.1 mm, magnified x200).Published as part of Boonzaaier-Davids, Melissa K., Florence, Wayne K. & Gibbons, Mark J., 2020, Novel taxa of Cheilostomata Bryozoa discovered in the historical backlogs of the Iziko South African Museum, pp. 105-133 in Zootaxa 4820 (1) on page 124, DOI: 10.11646/zootaxa.4820.1.5, http://zenodo.org/record/439737
FIGURE 2. A–E. Biflustra adenticulata n in Novel taxa of Cheilostomata Bryozoa discovered in the historical backlogs of the Iziko South African Museum
No full textFIGURE 2. A–E. Biflustra adenticulata n. sp. A. View of autozooids around the fenestrula (SAMC-A028915) (scale bar = 0.5 mm, magnified x50). B. Smaller, irregular shaped zooids (kenozooids) (SAMC-A028915) (scale bar = 0.1 mm, magnified x200). C. Frontal view of young zooids (SAMC-A028915) (scale bar = 0.2 mm, magnified x100). D. View of zooids near the fenestrula margin (SAMC-A029105) (scale bar = 0.2 mm, magnified x75). E. Multiporous distal mural septula (arrow) and kenozooids on the outer margin (SAMC-A029105) (scale bar = 0.2 mm, magnified x75).Published as part of Boonzaaier-Davids, Melissa K., Florence, Wayne K. & Gibbons, Mark J., 2020, Novel taxa of Cheilostomata Bryozoa discovered in the historical backlogs of the Iziko South African Museum, pp. 105-133 in Zootaxa 4820 (1) on page 108, DOI: 10.11646/zootaxa.4820.1.5, http://zenodo.org/record/439737
FIGURE 3. A–B. Chaperiopsis familiaris n in Novel taxa of Cheilostomata Bryozoa discovered in the historical backlogs of the Iziko South African Museum
No full textFIGURE 3. A–B. Chaperiopsis familiaris n. comb. (SAMC-A026415) A. Group of zooids, some with ovicells (scale bar = 0.4 mm, magnified x120). B. Closer view of some ovicelled zooids (scale bar = 0.2 mm, magnified x250). C–F. Aspidostoma sarcophagus n. sp. (SAMC-A029067). C. Zooids and kenozooids with cryptocystal pits (scale bar = 0.5 mm, magnified x35). D. Close-up of the orifice (scale bar = 0.2 mm, magnified x150). E. Developing antler-like processes (scale bar = 0.2 mm, magnified x100). F. Ovicelled zooid with well-developed antler-like processes (zooid on the left) (scale bar = 0.4 mm, magnified x50).Published as part of Boonzaaier-Davids, Melissa K., Florence, Wayne K. & Gibbons, Mark J., 2020, Novel taxa of Cheilostomata Bryozoa discovered in the historical backlogs of the Iziko South African Museum, pp. 105-133 in Zootaxa 4820 (1) on page 111, DOI: 10.11646/zootaxa.4820.1.5, http://zenodo.org/record/439737
FIGURE 6. A–F. Khulisa carolinae n. gen. et n in Novel taxa of Cheilostomata Bryozoa discovered in the historical backlogs of the Iziko South African Museum
No full textFIGURE 6. A–F. Khulisa carolinae n. gen. et n. sp. (SAMC-A029002) A. Group of autozooids and interzooidal avicularia (scale bar = 0.4 mm, magnified x50). B. Close-up of the interzooidal avicularium (scale bar = 0.2 mm, magnified x75). C. Autozooids and enlarged dimorphic zooid (scale bar = 0.4 mm, magnified x50). D. View of the apertural bar and detail of the distal pore plates (scale bar = 0.2 mm, magnified x100). E. Close-up of the apertural bar (scale bar = 0.1 mm, magnified x200). F. Orificial rim of an enlarged, dimorphic zooid (scale bar = 0.1 mm, magnified x200).Published as part of Boonzaaier-Davids, Melissa K., Florence, Wayne K. & Gibbons, Mark J., 2020, Novel taxa of Cheilostomata Bryozoa discovered in the historical backlogs of the Iziko South African Museum, pp. 105-133 in Zootaxa 4820 (1) on page 117, DOI: 10.11646/zootaxa.4820.1.5, http://zenodo.org/record/439737
Micropora erecta Boonzaaier-Davids & Florence & Gibbons 2020, n. sp.
No full text? Micropora erecta n. sp. (Fig. 4 A–F, Table 3) zoobank.org/ 4FAFEA9A-B13D-4699-B4F4-B7889135D1AC Material examined. Holotype: SAMC-A028821 (in ethanol), station AFR 866 (34°36.8’S, 19°16.4’E), Agulhas Bank, South Coast, South Africa, UCT Ecological Survey, dredge, depth 38 m, 9 January 1948. Additional material: SAMC-A073536 (dry), FAL 79; SAMC-A073463 (in ethanol), FAL 503; SAMC-A073482 (in ethanol), FAL 504; SAMC-A077326 (in ethanol), FAL 818; SAMC-A029102 (in ethanol), WCD 11. Additional comparative material: Micropora similis, SAMC-A026418 (holotype), station SM 163 (33°04.6’S, 28°06.6’E), off East London, Southeast Coast, South Africa, RV Meiring Naude Survey, heavy dredge, depth 90 m, 26 May 1978; SAMC-A026525, same station as above. Micropora latiavicula, SAMC-A028594 (holotype), Saldanha Bay (33°01’S, 17°59’E), West Coast, South Africa, collected by W. Florence, depth 15 m, 15 February 2001. Etymology. From the Latin, referring to the erect colony growth form. Diagnosis. Colony erect, bilaminar. Autozooids with cryptocyst smooth centrally and granular along the margins with small pseudopores; opesiules paired, finely toothed. Opesia with raised proximal rim and indentations. Interzooidal avicularia present. Ovicell hyperstomial; ooecium granular, smooth proximally. Description. Colony erect, forming broad, bilaminar branches, raising from an encrusting base; colour light brown to yellow in ethanol preserved material, creamy white in dried material. Autozooids elongate, rectangular, about 0.70 mm long by 0.30 mm wide, sometimes tapered proximally. Cryptocystal surface smooth centrally, granular along the zooidal margins, with 16–33 (N T = 10) circular, oval to irregularly shaped pseudopores of variable size; distolateral walls of autozooid forming a raised nodular rim below the opesia; rarely parts of the frontal shield unevenly raised by secondary calcification. Opesia wider than long, semicircular, with straight proximal border and paired opesiular indentations; paired opesiules finely toothed, placed proximal to the thickened orificial rim. No spines. Interzooidal avicularia present; crossbar complete, rostrum acute, directed obliquely distally. Ovicell hyperstomial, cleithral, with dimorphic opening; ooecium formed by the distal autozooid, with membranous ectooecium and calcified entooecium, partially covered by secondary calcification. In cleaned specimens, ooecium with granular surface, except for a narrow, smooth proximal border. Remarks. Globally, there are 70 known Micropora Gray, 1848 species, of which nearly half are extinct (www. bryozoa.net, accessed 06 June 2020).? Micropora erecta n. sp. closely resembles M. angusta MacGillivray, 1887, in the zooidal shape, the position of interzooidal avicularia and opesiules but it differs in having erect growth form and smooth cryptocyst centrally. Numerous other species (e.g. M. mawatarii Arakawa, 2016, M. plana Arakawa, 2016 and M. rimulata Canu & Bassler, 1929) differ from? M. erecta n. sp. in having evenly granular frontal surfaces. ? Micropora erecta n. sp. was also compared to Micropora species found in the Indian Ocean. Micropora latiavicula Florence, Hayward & Gibbons, 2007 from South Africa is distinguished by its slender zooids, interzooidal avicularia with broad sloping rostra that are directed obliquely distally, deep and circular opesiules proximal to the orifice on either side, and accessory opesiule openings subjacent to the primary opesiules. Another species reported previously from South Africa, M. similis Hayward & Cook, 1983, can be distinguished by the small distinct bosses adjacent to the opesia, slender autozooids and densely punctured cryptocyst (Hayward & Cook 1983).? Micropora erecta n. sp. differs from both, because it lacks accessory opesiules, has a smooth frontal surface (though granular along the zooidal margins) and indentations at the proximal corners of the opesia (Fig. 4C). This new species seemingly differs from typical Micropora species and other known genera in the family Microporidae Gray, 1848, and is only tentatively assigned to Micropora based on the structure of the ovicell (Ostrovsky 2013), semicircular orifice, paired opesiules and presence of interzooidal avicularia. ? Micropora erecta n. sp. was found from the Southwest Coast at Cape Peninsula to Agulhas Bank, including False Bay area, on the South Coast at 38–147 m depth.Published as part of Boonzaaier-Davids, Melissa K., Florence, Wayne K. & Gibbons, Mark J., 2020, Novel taxa of Cheilostomata Bryozoa discovered in the historical backlogs of the Iziko South African Museum, pp. 105-133 in Zootaxa 4820 (1) on pages 112-113, DOI: 10.11646/zootaxa.4820.1.5, http://zenodo.org/record/439737
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