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Filtering of Milankovitch Cycles by Earth's Geography
- David A. Short, John G. Mengel, Thomas J. Crowley, William T. Hyde, Gerald R. North
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- Journal:
- Quaternary Research / Volume 35 / Issue 2 / March 1991
- Published online by Cambridge University Press:
- 20 January 2017, pp. 157-173
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Earth's land-sea distribution modifies the temperature response to orbitally induced perturbations of the seasonal insolation. We examine this modification in the frequency domain by generating 800,000-yr time series of maximum summer temperature in selected regions with a linear, two-dimensional, seasonal energy balance climate model. Previous studies have demonstrated that this model has a sensitivity comparable to general circulation models for the seasonal temperature response to orbital forcing on land. Although the observed response in the geologic record is sometimes significantly different than modeled here (differences attributable to model limitations and feedbacks involving the ocean-atmosphere-cryosphere system), there are several results of significance: (1) in mid-latitude land areas the orbital signal is translated linearly into a large (>10°C) seasonal temperature response; (2) although the modeled seasonal response to orbital forcing on Antarctica is 6°C, the annual mean temperature effect (<2°C) is only about one-fifth that inferred from the Vostok ice core, and primarily restricted to periods near 41,000 yr; (3) equatorial regions have the richest spectrum of temperature response, with a 3000-yr phase shift in the precession response, plus some power near periods of 10,000–12,000 yr, 41,000 yr, 100,000 yr, and 400,000 yr. Peaks at 10,000–12,000 yr and 100,000 and 400,000 yr result from the twice-yearly passage of the sun across the equator. The complex model response in equatorial regions has some resemblance to geologic time series from this region. The amplification of model response over equatorial land masses at the 100,000-yr period may explain some of the observed large variance in this band in geologic records, especially in pre-Pleistocene records from times of little or no global ice volume.
In vivo measurement of the absorption of strontium in the rumen and small intestine of sheep as an index of calcium absorption capacity
- Michelle L. Hyde, David R. Fraser
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- Journal:
- British Journal of Nutrition / Volume 112 / Issue 5 / 14 September 2014
- Published online by Cambridge University Press:
- 07 July 2014, pp. 718-724
- Print publication:
- 14 September 2014
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In the present study, a method was developed for determining the alimentary tract Ca absorption capacity of ruminant animals by measuring the absorption rate of Sr after the administration of an oral dose of strontium chloride acting as a tracer analogue of Ca. A close correlation between the absorption rates of the two tracers was observed upon simultaneous administration of an oral dose of stable Sr and radioactive calcium (r 0·98). The Ca absorption capacity of the rumen and small intestine was determined separately by either directing the solution into the rumen or by diverting it into the post-ruminal tract by vasopressin-induced closure of the ruminoreticular groove. The animals were treated with 1α-hydroxyvitamin D3 administered via subcutaneously implanted mini-osmotic pumps. The effect of elevated plasma 1,25-dihydroxycholecalciferol concentrations on the Ca absorption capacity of the alimentary tract was then determined. An increased rate of Sr absorption was observed in both the rumen and small intestine of sheep after treatment, although it is unclear whether the rumen possesses the same vitamin D-dependent Ca absorption pathway as the small intestine.
Looking Backward, Looking Forward: MLA Members Speak
- April Alliston, Elizabeth Ammons, Jean Arnold, Nina Baym, Sandra L. Beckett, Peter G. Beidler, Roger A. Berger, Sandra Bermann, J.J. Wilson, Troy Boone, Alison Booth, Wayne C. Booth, James Phelan, Marie Borroff, Ihab Hassan, Ulrich Weisstein, Zack Bowen, Jill Campbell, Dan Campion, Jay Caplan, Maurice Charney, Beverly Lyon Clark, Robert A. Colby, Thomas C. Coleman III, Nicole Cooley, Richard Dellamora, Morris Dickstein, Terrell Dixon, Emory Elliott, Caryl Emerson, Ann W. Engar, Lars Engle, Kai Hammermeister, N. N. Feltes, Mary Anne Ferguson, Annie Finch, Shelley Fisher Fishkin, Jerry Aline Flieger, Norman Friedman, Rosemarie Garland-Thomson, Sandra M. Gilbert, Laurie Grobman, George Guida, Liselotte Gumpel, R. K. Gupta, Florence Howe, Cathy L. Jrade, Richard A. Kaye, Calhoun Winton, Murray Krieger, Robert Langbaum, Richard A. Lanham, Marilee Lindemann, Paul Michael Lützeler, Thomas J. Lynn, Juliet Flower MacCannell, Michelle A. Massé, Irving Massey, Georges May, Christian W. Hallstein, Gita May, Lucy McDiarmid, Ellen Messer-Davidow, Koritha Mitchell, Robin Smiles, Kenyatta Albeny, George Monteiro, Joel Myerson, Alan Nadel, Ashton Nichols, Jeffrey Nishimura, Neal Oxenhandler, David Palumbo-Liu, Vincent P. Pecora, David Porter, Nancy Potter, Ronald C. Rosbottom, Elias L. Rivers, Gerhard F. Strasser, J. L. Styan, Marianna De Marco Torgovnick, Gary Totten, David van Leer, Asha Varadharajan, Orrin N. C. Wang, Sharon Willis, Louise E. Wright, Donald A. Yates, Takayuki Yokota-Murakami, Richard E. Zeikowitz, Angelika Bammer, Dale Bauer, Karl Beckson, Betsy A. Bowen, Stacey Donohue, Sheila Emerson, Gwendolyn Audrey Foster, Jay L. Halio, Karl Kroeber, Terence Hawkes, William B. Hunter, Mary Jambus, Willard F. King, Nancy K. Miller, Jody Norton, Ann Pellegrini, S. P. Rosenbaum, Lorie Roth, Robert Scholes, Joanne Shattock, Rosemary T. VanArsdel, Alfred Bendixen, Alarma Kathleen Brown, Michael J. Kiskis, Debra A. Castillo, Rey Chow, John F. Crossen, Robert F. Fleissner, Regenia Gagnier, Nicholas Howe, M. Thomas Inge, Frank Mehring, Hyungji Park, Jahan Ramazani, Kenneth M. Roemer, Deborah D. Rogers, A. LaVonne Brown Ruoff, Regina M. Schwartz, John T. Shawcross, Brenda R. Silver, Andrew von Hendy, Virginia Wright Wexman, Britta Zangen, A. Owen Aldridge, Paula R. Backscheider, Roland Bartel, E. M. Forster, Milton Birnbaum, Jonathan Bishop, Crystal Downing, Frank H. Ellis, Roberto Forns-Broggi, James R. Giles, Mary E. Giles, Susan Blair Green, Madelyn Gutwirth, Constance B. Hieatt, Titi Adepitan, Edgar C. Knowlton, Jr., Emanuel Mussman, Sally Todd Nelson, Robert O. Preyer, David Diego Rodriguez, Guy Stern, James Thorpe, Robert J. Wilson, Rebecca S. Beal, Joyce Simutis, Betsy Bowden, Sara Cooper, Wheeler Winston Dixon, Tarek el Ariss, Richard Jewell, John W. Kronik, Wendy Martin, Stuart Y. McDougal, Hugo Méndez-Ramírez, Ivy Schweitzer, Armand E. Singer, G. Thomas Tanselle, Tom Bishop, Mary Ann Caws, Marcel Gutwirth, Christophe Ippolito, Lawrence D. Kritzman, James Longenbach, Tim McCracken, Wolfe S. Molitor, Diane Quantic, Gregory Rabassa, Ellen M. Tsagaris, Anthony C. Yu, Betty Jean Craige, Wendell V. Harris, J. Hillis Miller, Jesse G. Swan, Helene Zimmer-Loew, Peter Berek, James Chandler, Hanna K. Charney, Philip Cohen, Judith Fetterley, Herbert Lindenberger, Julia Reinhard Lupton, Maximillian E. Novak, Richard Ohmann, Marjorie Perloff, Mark Reynolds, James Sledd, Harriet Turner, Marie Umeh, Flavia Aloya, Regina Barreca, Konrad Bieber, Ellis Hanson, William J. Hyde, Holly A. Laird, David Leverenz, Allen Michie, J. Wesley Miller, Marvin Rosenberg, Daniel R. Schwarz, Elizabeth Welt Trahan, Jean Fagan Yellin
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- Journal:
- PMLA / Publications of the Modern Language Association of America / Volume 115 / Issue 7 / December 2000
- Published online by Cambridge University Press:
- 23 October 2020, pp. 1986-2078
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- December 2000
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Cloning and tissue localization of a novel zebrafish RdgB homolog that lacks a phospholipid transfer domain
- VECHESLAV A. ELAGIN, RAYA B. ELAGINA, CHRISTOPHER J. DORO, THOMAS S. VIHTELIC, DAVID R. HYDE
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- Journal:
- Visual Neuroscience / Volume 17 / Issue 2 / March 2000
- Published online by Cambridge University Press:
- 01 March 2000, pp. 303-311
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The retinal degeneration B (RdgB) protein family is characterized by an amino-terminal phosphatidylinositol transfer protein (PITP) domain, several hydrophobic domains, and a highly conserved carboxyl terminus. We identified a zebrafish RdgB homolog (pl-RdgB) that lacks the amino-terminal PITP domain, while retaining over 45% amino acid identity with the two mouse RdgB proteins (M-RdgB1 and M-RdgB2). Unlike the widespread retinal expression observed for other vertebrate RdgB homologs, pl-RdgB is restricted in the retina to the cone cell inner segments. The pl-RdgB protein is also expressed in the brain, although its distribution is different than the other RdgB homologs. Analogous to M-RdgB2, pl-RdgB protein is extracted from a retinal homogenate by guanidine and not by Triton X-100. Thus, pl-RdgB and likely all the identified RdgB homologs are not integral membrane proteins, but may associate with the membrane through protein–protein interactions. While expression of either murine RdgB homolog restored the defective light response and prevented retinal degeneration in rdgB mutant flies, expressing zebrafish pl-RdgB in Drosophila rdgB2 null mutants slowed retinal degeneration without restoring the electrophysiological light response. Thus, pl-RdgB may define a previously unrecognized protein family, which includes the other RdgB homologs, that act through a protein complex to maintain photoreceptor viability.
Cloning and characterization of six zebrafish photoreceptor opsin cDNAs and immunolocalization of their corresponding proteins
- THOMAS S. VIHTELIC, CHRISTOPHER J. DORO, DAVID R. HYDE
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- Journal:
- Visual Neuroscience / Volume 16 / Issue 3 / May 1999
- Published online by Cambridge University Press:
- 01 May 1999, pp. 571-585
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Zebrafish (Danio rerio) represents an excellent genetic model for vertebrate visual system studies. Because the opsin proteins are ideal markers of specific photoreceptor cell types, we cloned six different zebrafish opsin cDNAs. Based on pairwise alignments and phylogenetic comparisons between the predicted zebrafish opsin amino acid sequences and other vertebrate opsins, the cDNAs encode rhodopsin, two different green opsins (zfgr1 and zfgr2), a red, a blue, and an ultraviolet opsin. Phylogenetic analysis indicates the zfgr1 protein occupies a well-resolved dendrogram branch separate from the other green opsins examined, while zebrafish ultraviolet opsin is closely related to the human blue- and chicken violet-sensitive proteins. Polyclonal antisera were generated against individual bacterial fusion proteins containing either the red, blue, or ultraviolet amino termini or the rod or green opsin carboxyl termini. Immunolocalization on adult zebrafish frozen sections demonstrates the green and red opsins are each expressed in different members of the double cone cell pair, the blue opsin is detected in long single cones, and the ultraviolet opsin protein is expressed in the short single cones. In 120-h postfertilization wholemounts, green, red, blue, and ultraviolet opsin-positive cells are detected in an orderly arrangement throughout the entire retina. The antibodies' photoreceptor-type specificity indicates they will be useful for characterizing both wild-type and mutant zebrafish retinas.
Is There Cognitive Decline in Schizophrenia?: A Cross-sectional Study
- Thomas M. Hyde, Safia Nawroz, Terry E. Goldberg, Llewellyn B. Bigelow, David Strong, Jill L. Ostrem, Daniel R. Weinberger, Joel E. Kleinman
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- Journal:
- The British Journal of Psychiatry / Volume 164 / Issue 4 / April 1994
- Published online by Cambridge University Press:
- 02 January 2018, pp. 494-500
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- April 1994
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The issue of progressive cognitive decline in patients with schizophrenia has been debated. We performed a cross-sectional study of patients with chronic schizophrenia, aged from 18 to 69 years, in order to address this issue. The patients included in this study passed a rigorous screen for any comorbid condition with an adverse impact on central nervous system function. We assessed intellectual deterioration with a battery of neuropsychological tests known to be sensitive to cognitive impairment in progressive dementia. No evidence of accelerated intellectual decline was found. No significant differences were found between the five age-derived cohorts (18–29, 30–39, 40–49, 50–59, and 60–69 years of age) on the Mini-Mental State Examination, Dementia Rating Scale, or other tests sensitive to dementia. While performance on the Boston Naming Test significantly declined with age, this was mainly due to age rather than duration of illness. However, it is important to note that mean performances on the majority of the tests were abnormal across all cohorts studied. These results suggest that intellectual function does not markedly decline during the adulthood of patients with schizophrenia. The course of schizophrenia is more consistent with a static encephalopathy than a dementing disorder.
Excavations at Stackpole Warren, Dyfed
- D. G. Benson, J. G. Evans, G. H. Williams, T. Darvill, A. David, D. Brennan, A. E. Caseldine, R. Cole, Q. Dresser, L. M. Hyde, T. O'connor, J. L. Wilkinson
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- Journal:
- Proceedings of the Prehistoric Society / Volume 56 / 1990
- Published online by Cambridge University Press:
- 18 February 2014, pp. 179-245
- Print publication:
- 1990
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Excavations of sites spanning the Beaker to early Roman periods at Stackpole Warren, Dyfed, are described. The sites are in an area of blown sand which enhanced their preservation and led to the separation of several horizons. The earliest is a buried soil beneath the blown sand which contained Mesolithic to Bronze Age artefacts. At site A, there was a roundhouse associated with Early Bronze Age pottery and dated to 1620±70 and 1400±70 BC uncal., and two other roundhouses, one possibly of Beaker age. After a period of soil formation, a ritual complex of Later Bronze Age date was established, this contemporary with the earliest besanding of the area; it included a stone setting of more than 2000 small stones, an alignment of small water-worn stones and a standing stone. A cremation gave a latest date of 940±70 BC uncal. Other Later Bronze Age activity is recorded at site G/J in the form of a rectangular enclosure, possibly unfinished.
Late Iron Age to early Romano-British settlement was present at sites A and B, consisting of scatters of occupation debris, burnt mounds, cooking pits, hearths and houses, some of stone, some of timber, all taking place in an area being intermittently besanded.
Peripheral to the religious and domestic sites, a field system was excavated. The earliest phase was a linear earthwork from which a C14 date of 400±70 BC uncal. was obtained from charcoal in the ditch. After the decay of this, rectangular fields with stone walls were laid out, one along the line of the erstwhile earthwork, this taking place around the end of the Iron Age as dated by C14 of charcoal directly beneath a wall to 90±70 BC uncal. Some of the fields had been cultivated by a succession of cross- and one-way-ploughing, others used for cattle.
An assemblage of 763 flints included a few Mesolithic artefacts but was mostly of Late Neolithic and Bronze Age date. A succession of ceramic assemblages included a small Middle Neolithic group (4 vessels), two distinct Beaker groups, one early (Lanting and van der Waals steps 1–3 (8 vessels), one late (steps 3–6) (45 vessels), an Early Bronze Age group of collared urns (43 vessels) and a Later Bronze Age group (26 vessels).
Environmental data was not prolific but there was a small quantity of animal bone, mostly cattle and sheep, and cereal grain, mostly barley with some wheat. Marine molluscs were present but sparsely utilized and there was no other indication of the exploitation of the coastal resources such as seals, birds, fish andiseaweed. Land Mollusca indicated open country from the Iron Age onwards when the record begins.
The importance of the site is in the ritual complex from site A, the succession of Iron Age/Romano-British occupation horizons, the succession of ceramic assemblages, the field system and the fact that blown sand horizons have allowed the preservation and separation of the sequence much of which would have been at best conflated in to a single horizon or at worst destroyed. Otherwise, there is no evidence that the site was in any way special with regard to the relationship of human activity and sand deposition until the Middle Ages when the area was used as a rabbit warren. Nor was the coastal location important, at least as could be determined by the results. This was a representative of a succession of later prehistoric farming communities and their various domestic, ritual and sepulchral activities in lowland Dyfed.