345 research outputs found
The effect of static incubation on the yolk sac vasculature of the Japanese quail (Coturnix c. japonica)
No full textStatic incubation affects early embryonic development with, notably, a reduction area vasculosa expansion and diminished sub-embryonic fluid (SEF) volume, effects produced during a ‘critical’ period (3-7 days in the chick) (Baggott et al., 2002). Also, as noted by Babiker & Baggott (1992), SEF is produced in bulk only after the appearance of the yolk sac vasculature (YSV), which undergoes extensive proliferation before and during the critical period. Quantification of such changes in YSV requires estimates of both the quantity of vessels and the degree of branching. In the chick, total vessel length increased linearly up to 160h of incubation, whereas branching was maximal by about 96 h (Vico et al., 1998); so, by the critical period branching is complete yet vessel growth continues. It would seem likely, therefore, that a lack of turning would reduce both measures of YSV proliferation during the critical period. In quail the effect of static incubation seems not to be simply due to retardation of YSV proliferation, as vascular density index was reduced in unturned eggs in the middle of the critical period, only to increase again by 168 h. Also early in the critical period fractal dimension was 1.70 (as in the chick, Vico et al., 1998), yet then decreased in unturned eggs, although not significantly, and subsequently an increase occurred. Thus during the critical period static incubation specifically affects the structuring of the YSV but whether this is because of, or independent of, retardation of area vasculosa expansion is not known
Farewell to reality: how modern physics has betrayed the search for scientific truth
No full textFrom acclaimed science author Jim Baggott, a pointed critique of modern theoretical physics. In this stunning new volume, Jim Baggott argues that there is no observational or experimental evidence for many of the ideas of modern theoretical physics: super-symmetric particles,super strings, the multiverse, the holographic principle,or the anthropic cosmological principle. These theories are not only untrue, it is not even science. It is fairy-tale physics: fantastical, bizarre and often outrageous, perhaps even confidence-trickery. This book provides a much-needed antidote. Informed,comprehensive, and balanced, it offers lay readers the latest ideas about the nature of physical reality while clearly distinguishing between fact and fantasy. With its engaging portraits of many central figures of modern physics, including Paul Davies, John Barrow, Brian Greene, Stephen Hawking, and Leonard Susskind, it promises to be essential reading for all readers interested in what we know and don’t know about the nature of the universe and reality itself
Interactive learning in biology with PhotoCD and associated software
No full textThis paper describes the pioneering development of flexible‐learning courseware in the teaching and learning of cell biology using a novel optical disk‐based technology — PhotoCD — and its associated computer software. The use of this format in an educational context for the manipulation of, and interaction with, photographic images in electronic form is presented for the first time. Examples of courseware which use PhotoCD, image‐enhancement and image‐management software in biology education are given, and an evaluation by undergraduates in biology education (student teachers) of these teaching and learning strategies is presente
Portrait of the South Australian staff ready for their Christmas Party, from left to right, Ted Atkinson, Ross Fowler, Snow Adams, Spencer Baggott, S. Britton, D. Sawtell, Alan Dougherty, Dick Christie, J. Richards, Miss R. Manning, Miss Pat Haigh and Miss Pat King, December, 1948 [picture] .
No full textPart of the collection: Ampol and Caltex photograph collection.; Title devised by cataloguer based on information supplied by donor.; Condition: Good.; Inscriptions: "December 1948 South Australia staff ready for Christmas Party at "The Berkley Hotel". L. to R.: H. Atkinson, R. Fowler, L. Adams, S. Baggott, S. Britton (Manager), D. Sawtell, A. Dougherty, R. Christie, J. Richards, Misses R. Manning, P. Haigh, P. King (Absent - E. Bond)." -- typed in ink on a label below the photo.; Also available in an electronic version via the Internet at: http://nla.gov.au/nla.pic-an24648091
Electrolyte and Water Balance of the Early Avian Embryo: Effects of Egg Turning
No full textFormation of sub-embryonic fluid (SEF) is a key aspect of the physiology of the early avian embryo.Here we review the process of SEF formation and the factors which influence its composition and the rate of SEF production and depletion in the Japanese quail and domestic fowl.There is particular emphasis on the role of turning of the egg during incubation and we briefly consider
the broader role of egg turning during avian incubation. The bulk of the review deals with the growth of the area vasculosa of the yolk sac membrane, the cellular processes of SEF formation, and the water and electrolyte physiology of the avian embryo during the first half of incubation.We conclude with a brief discussion of the areas for future investigation
Effect of egg turning and incubation time on carbonic anhydrase gene expression in the blastoderm of the Japanese quail (Coturnix c. japonica)
No full text(1) The gene expression of carbonic anhydrase, a key enzyme for the production sub-embryonic fluid (SEF), was assessed in turned and unturned eggs of the Japanese quail. The plasma membrane-associated isoforms CA IV, CAIX, CA XII, CA XIV, and the cytoplasmic isoform CA II, were
investigated in the extra-embryonic tissue of the blastoderm and in embryonic blood.
(2) Eggs were incubated at 37.6C, c. 60% R.H., and turned hourly (90 ) or left unturned. From 48 to 96 hours of incubation mRNA was extracted from blastoderm tissue, reverse-transcribed to cDNA and quantified by real-time qPCR using gene-specific primers. Blood collected at 96h was processed identically.
(3) Blastoderm CAIV gene expression increased with the period of incubation only in turned eggs, with maxima at 84 and 96h of incubation. Only very low levels were found in blood.
(4) Blastoderm CA II gene expression was greatest at 48 and 54h of incubation, subsequently declining to much lower levels and una ected by turning. Blood CA II gene expression was about 25-fold greater than that in the blastoderm.
(5) The expression of CA IX in the blastoderm was the highest of all isoforms, yet unaffected by turning.
CA XII did not amplify and CA XIV was present at unquantifiable low levels.
(6) It is concluded that solely gene expression for CA IV is sensitive to egg turning, and that increased CA IV gene expression could account for the additional SEF mass found at 84-96h of incubation.
in embryos of turned eggs
Portrait of the office staff consisting of Tom Pain, K. Francis, J. Sedgley, Spencer Baggott, Ted Klingberg, A. Hollings, V. West, P. Gray, Irene Dougherty, B. Robin, M. O'Toole, Betty Matson, Barbara Reed, Pat Bradshaw, R. Lennon, B. Buckfield, Jill Ranford, A. Haigh, P. McIntyre, Y. Mitchell and P. Thirsk, 20th January, 1952 [picture] .
No full textPart of the collection: Ampol and Caltex photograph collection.; Title devised by cataloguer based on information supplied by donor.; Inscriptions: "Office Staff as at 20th January 1952. (L. to R.) Back Row: T. Pain, K. Francis, J. Sedgley, S. Baggott (Accountant), T. Klingberg (Credit Manager), A. Hollings (Chief Clerk), V. West, P. Gray, Irene Dougherty, B. Robin, M. O'Toole, Betty Matson, B. Reed, P. Bradshaw, R. Lennon, B. Buckfield, J. Ranford, A. Haigh, P. McIntyre, Y. Mitchell, P. Thirsk." -- typed in ink on label below photo.; Condition: Good.; Also available in an electronic version via the Internet at: http://nla.gov.au/nla.pic-an24664026
Role of carbon dioxide and ion transport in the formation of sub-embryonic fluid by the blastoderm of the Japanese quail
No full text1. The explanted blastoderm of the Japanese quail was used to explore the role of ions and carbon dioxide in determining the rate of sub-embryonic fluid (SEF) production between 54 and 72 h of incubation.
2. Amiloride, an inhibitor of Na+/H+ exchange, at concentrations of 10-3 to 10-6 M substantially decreased the rate of SEF production when added to the albumen culture medium. N-ethylmaleimide, an inhibitor of V type H+ ATPase, also decreased this rate but only to a small extent at the highest dose applied, 10-3 M. Both inhibitors had no effect on SEF production when added to the SEF. 3. The inhibitors of cellular bicarbonate and chloride exchange, 4-acetamido-4-'isothiocyano-2, 2-'disulphonic acid (SITS) and 4,4'diisothiocyanostilbene-2,2-'disulphonic acid (DIDS), had no effect upon SEF production.
4. Ouabain, an inhibitor of Na+/K+ ATPase, decreased SEF production substantially at all concentrations added to the SEF (10-3 to 10-6 M). Three sulphonamide inhibitors of carbonic anhydrase, acetazolamide, ethoxzolamide and benzolamide, decreased SEF production when added to the SEF at concentrations of 10-3 to 10-6 M. Benzolamide was by far the most potent. Neither ouabain nor the sulphonamides altered SEF production when added to the albumen culture medium.
5. Using a cobalt precipitation method, carbonic anhydrase activity was localised to the endodermal cells of the area vasculosa. The carbonic anhydrase activity was primarily associated with the lateral plasma membranes, which together with the potent inhibitory effect of benzolamide, suggests the carbonic anhydrase of these cells is the membrane-associated form, CA IV.
6. The changes in SEF composition produced by inhibitors were consistent with the production of SEF by local osmotic gradients.
7. It is concluded that a Na+/K+ ATPase is located on the basolateral membranes of the endodermal cells of the area vasculosa , and that a sodium ion/hydrogen ion exchanger is located on their apical surfaces. Protons for this exchanger would be provided by the hydration of CO2 catalysed by the membrane-associated carbonic anhydrase. Furthermore, it is proposed that the prime function of the endodermal cells of the area vasculosa is the production of SEF
Polypropylene fibre reinforcement of hardened cement paste
No full textThis thesis considers the tensile deformation characteristics ofpolypropylene fibre reinforced hardened cement paste having heterogeneousfibre geometries and a range of volume concentrations.Polypropylene fibres were prepared under various manufacturingconditions using a laboratory extruder, to ascertain the effect ofthese conditions on fibre characteristics.The relevant properties of cement paste likely to influence thepolypropylene fibres and the eventual composite were investigated.An investigation of continuous aligned fibre composites in tension,containing various volume concentrations of fibres, showed thatmultiple cracking occurred despite the elastic modulus of the fibrebeing considerably lower than that of the hardened cement paste.Factors which enabled fibre/matrix contact to be maintained duringthe multiple cracking process, despite the unfavourable Poisson'sratio of polypropylene, were considered.Discontinuous aligned fibre composites were tested in tension, toascertain the effect of volume concentration and length of fibres onthe shear stress transfer between fibre and matrix and on multiplecracking.Composites containing parallel fibres, with fibre directions atvarying angles to the direction of applied tensile stress, allowedan assessment to be made of the role of inclination. Crackdistributions, pull-out behaviour of fibres and the ultimate stressof composites were investigated.Finally, random fibre reinforced composites were evaluated to providea comparison with the Continuous, Discontinuous and Inclined fibrereinforced systems.In addition to determining the mechanical deformation of the variouscomposites, the acoustic emission associated with internal deformationmechanisms was studied. This was undertaken with equipment capableof monitoring a range of acoustic pulse parameters
Steve Almond, 32nd Annual ODU Literary Festival
No full textSteve Almond is the author of two story collections, My Life in Heavy Metal and The Evil B.B. Chow, the novel Which Brings Me to You (with Julianna Baggott), and the non-fiction book Candyfreak. His new book is a collection of essays, (Not That You Asked). He lives outside Boston with his wife, two children, and mounting debt. His online home is www.stevenalmond.com
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