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Articles 1 - 7 of 7
Full-Text Articles in Life Sciences
New Caribbean Locality For The Extinct Great White Shark Carcharodon, Clare Flemming, Donald A. Mcfarlane
New Caribbean Locality For The Extinct Great White Shark Carcharodon, Clare Flemming, Donald A. Mcfarlane
WM Keck Science Faculty Papers
Carcharodon is represented by a single upper tooth (Fig. 1) which we extracted from the eroding Pliocene limestone wall, some six meters above the floor at the northern end of Darby Sink. Much of the tooth is missing, but the remaining portion includes features diagnostic of this genus. The tooth conforms in size and morphology to Carcharodon megalodon (Agassiz, 1843), an extinct great white shark.
A Second Pre-Wisconsinan Locality For The Extinct Jamaican Rodent, Clidomys (Rodentia: Heptaxodontidae), Donald A. Mcfarlane, Joyce Lundberg, Clare Flemming, Ross D. E. Macphee, Stein-Erik Lauritzen
A Second Pre-Wisconsinan Locality For The Extinct Jamaican Rodent, Clidomys (Rodentia: Heptaxodontidae), Donald A. Mcfarlane, Joyce Lundberg, Clare Flemming, Ross D. E. Macphee, Stein-Erik Lauritzen
WM Keck Science Faculty Papers
Clidomys is the most distinctive but least well known member of the late Quaternary terrestrial mammal fauna of Jamaica. Here we report the second dated locality for this genus. The Illinoisan age we report further strengthens arguments we have made elsewhere, that Clidomys represents an early - probably pre-Wisconsinan - extinction that contrasts with the growing record of Holocene extinctions in the Antilles.
The Age Of The Kirkdale Cave Palaeofauna, Donald A. Mcfarlane, Derek C. Ford
The Age Of The Kirkdale Cave Palaeofauna, Donald A. Mcfarlane, Derek C. Ford
WM Keck Science Faculty Papers
The Kirkdale Cave palaeofauna represents the original and classic 'warm', interglacial mammalian cave deposit in Britain. Although long considered to be 'Ipswichian' in age, no previous attempts to obtain radiometric dates have been recorded. Here we report a uranium-series disequilibrium date of 121,000 ± 4000 yr BP on a flowstone capping that overlay the original bone bed. The precision of the date exceeds that obtained at any other British Interglacial cave site, and permits tentative correlation with the high precision ice core records now available.
Energy Absorption During Running By Leg Muscles In A Cockroach, Robert J. Full, Darrell R. Stokes, Anna N. Ahn, Robert K. Josephson
Energy Absorption During Running By Leg Muscles In A Cockroach, Robert J. Full, Darrell R. Stokes, Anna N. Ahn, Robert K. Josephson
All HMC Faculty Publications and Research
Biologists have traditionally focused on a muscle's ability to generate power. By determining muscle length, strain and activation pattern in the cockroach Blaberus discoidalis, we discovered leg extensor muscles that operate as active dampers that only absorb energy during running. Data from running animals were compared with measurements of force and power production of isolated muscles studied over a range of stimulus conditions and muscle length changes. We studied the trochanter-femoral extensor muscles 137 and 179, homologous leg muscles of the mesothoracic and metathoracic legs, respectively. Because each of these muscles is innervated by a single excitatory motor axon, …
Fission Yeast Mitotic Regulator Dsk1 Is An Sr Protein-Specific Kinase, Zhaohua Irene Tang, Mitsuhiro Yanagida, Ren-Jang Lin
Fission Yeast Mitotic Regulator Dsk1 Is An Sr Protein-Specific Kinase, Zhaohua Irene Tang, Mitsuhiro Yanagida, Ren-Jang Lin
WM Keck Science Faculty Papers
Intricate interplay may exist between pre-mRNA splicing and the cell division cycle, and fission yeast Dsk1 appears to play a role in such a connection. Previous genetic analyses have implicated Dsk1 in the regulation of chromosome segregation at the metaphase/anaphase transition. Yet, its protein sequence suggests that Dsk1 may function as a kinase specific for SR proteins, a family of pre-mRNA splicing factors containing arginine-serine repeats. Using an in vitro system with purified components, we showed that Dsk1 phosphorylated human and yeast SR proteins with high specificity. The Dsk1-phosphorylated SF2/ASF protein was recognized strongly by a monoclonal antibody (mAb104) known …
Magnetostratigraphy Of Cueva Del Aleman, Isla De Mona, Puerto Rico And The Species Duration Of Audobon's Shearwater, Bruce C. Panuska, John M. Mylroie, Darrell Armentrout, Donald A. Mcfarlane
Magnetostratigraphy Of Cueva Del Aleman, Isla De Mona, Puerto Rico And The Species Duration Of Audobon's Shearwater, Bruce C. Panuska, John M. Mylroie, Darrell Armentrout, Donald A. Mcfarlane
WM Keck Science Faculty Papers
Magnetostratigraphic analysis of deposits exposed in Cueva del Aleman shows two reversed and two normal chronozones. The lower normal polarity event is observed in a clastic dike and probably predates initial cave formation. Sediments deposited inside the cave proper show a R-N-R sequence and probably date to at least 1.8 Ma. A fossiliferous clastic dike contains normal polarity with an overlying reversed magnetozone. Audubon’s Shearwater (bird) bones occur in the dike, which is tentatively correlated with the lower N polarity zone predating cave formation. If this correlation is correct, the Audubon’s Shearwater (Puffinus lherminieri) range can be extended back to …
Computers And Learning, William K. Purves, Mary E. Williams
Computers And Learning, William K. Purves, Mary E. Williams
All HMC Faculty Publications and Research
The important questions for instructors to address concern what skills the student is to learn and how the student is to be motivated to acquire those skills. Questions about simulations, graphics tools, and the like are unimportant until the first two questions have been answered adequately. We discuss the role of explanation by students and describe a mechanism for motivating students to learn.