760 research outputs found
Late Toarcian marine gastropods from the Cleveland Basin, UK: systematics, palaeobiogeography and contribution to biotic recovery from the early Toarcian extinction event
No full textAs part of a study to evaluate the recovery from the early Toarcian extinction event in the Cleveland Basin, 477 new gastropod specimens were collected from mid-late Toarcian rocks of the Ravenscar section, North Yorkshire, UK. The gastropods were preserved in two modes: 1) specimens preserved with recrystallized shells, mainly in the Whitby Mudstone Formation, but also some in the Blea Wyke Sandstone Formation; 2) specimens preserved as external moulds in mineralized patches of shells in the Yellow Sandstone Member.Fil: Ferrari, Silvia Mariel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Instituto Patagónico de Geología y Paleontología; ArgentinaFil: Little, Crispin. University of Leeds; Reino UnidoFil: Atkinson, Jed W.. University of Leeds; Reino Unido3rd International Workshop Toarcian Oceanic Anoxic Event: Impact on marine organisms and ecosystemsErlangenAlemaniaGeoZentru
Extinction cascades, community collapse, and recovery across a Mesozoic hyperthermal event
No full textMass extinctions are considered to be quintessential examples of Court Jester drivers of macroevolution, whereby abiotic pressures drive a suite of extinctions leading to huge ecosystem changes across geological timescales. Most research on mass extinctions ignores species interactions and community structure, limiting inference about which and why species go extinct, and how Red Queen processes that link speciation to extinction rates affect the subsequent recovery of biodiversity, structure and function. Here, we apply network reconstruction, secondary extinction modelling and community structure analysis to the Early Toarcian (Lower Jurassic; 183 Ma) Extinction Event and recovery. We find that primary extinctions targeted towards infaunal guilds, which caused secondary extinction cascades to higher trophic levels, reproduce the empirical post-extinction community most accurately. We find that the extinction event caused a switch from a diverse community with high levels of functional redundancy to a less diverse, more densely connected community of generalists. Recovery was characterised by a return to pre-extinction levels of some elements of community structure and function prior to the recovery of biodiversity. Full ecosystem recovery took ~7 million years at which point we see evidence of dramatically increased vertical structure linked to the Mesozoic Marine Revolution and modern marine ecosystem structure
Seabed foraging by Antarctic krill: Implications for stock assessment, bentho-pelagic coupling, and the vertical transfer of iron
No full textA compilation of more than 30 studies shows that adult Antarctic krill (Euphausia superba) may frequent benthic habitats year-round, in shelf as well as oceanic waters and throughout their circumpolar range. Net and acoustic data from the Scotia Sea show that in summer 2-20% of the population reside at depths between 200 and 2000 m, and that large aggregations can form above the seabed. Local differences in the vertical distribution of krill indicate that reduced feeding success in surface waters, either due to predator encounter or food shortage, might initiate such deep migrations and results in benthic feeding. Fatty acid and microscopic analyses of stomach content confirm two different foraging habitats for Antarctic krill: the upper ocean, where fresh phytoplankton is the main food source, and deeper water or the seabed, where detritus and copepods are consumed. Krill caught in upper waters retain signals of benthic feeding, suggesting frequent and dynamic exchange between surface and seabed. Krill contained up to 260 nmol iron per stomach when returning from seabed feeding. About 5% of this iron is labile, i.e., potentially available to phytoplankton. Due to their large biomass, frequent benthic feeding, and acidic digestion of particulate iron, krill might facilitate an input of new iron to Southern Ocean surface waters. Deep migrations and foraging at the seabed are significant parts of krill ecology, and the vertical fluxes involved in this behavior are important for the coupling of benthic and pelagic food webs and their elemental repositories
Premnophilus maiai Atkinson & Flechtmann 2023, new species
No full textPremnophilus maiai Atkinson & Flechtmann, new species Fig. 8 A–D urn:lsid:zoobank.org:act: 461E6F51-FECC-46D5-94AA-224517197E97 Diagnosis. This species and P. bertii differ from those previously described here in that the declivity is clearly sulcate, with a rounded margin from the declivital apex almost to its base which bears 2–3 denticles. There are no granules on the declivital face. Female. Total length: 2.10 mm, maximum width: 0.75 mm, length of elytra: 1.18 mm, total length / width: 2.80, elytra length / width: 1.57, pronotal length / width: 1.23 (n=1). Elytra reddish brown, pronotum yellowish brown. Frons shining, smooth, with small, shallow punctures, these widely spaced, some with erect setae slightly longer than the distance between punctures. Punctures becoming granulate near epistoma. A very weakly elevated, longitudinal carina runs from well above the eyes but ends before the epistomal margin. First segment of anterior face of antennal club corneus, bisinuate, middle portion not reaching middle of club; distal part densely pubescent without visible sutures; pubescent area not reaching base of antennal laterally. Posterior face with corneous portion occupying 3/4 club length, pubescent distally, lateral areas not pubescent. Anterior margin of pronotum bluntly rounded, subtruncate, asperities on its leading edge notably larger than those on the rest of the anterior slope. Summit slightly anterior to middle, asperities short, flattened, with about 3 their thickness, becoming shorter towards summit. Pronotal disc shining; punctures shallow, small, widely spaced. Erect setae on disc, spaced by about their length. Elytral disc shining, smooth. Striae not impressed, punctures shallow, with short recumbent setae. Interstriae about 2 width of striae with mostly uniseriate erect setae, their length slightly longer than interstrial width. Interstriae becoming weakly granulate near base of declivity. Declivity steep occupying 25% of declivital length in lateral view; steep, with face sulcate from the base to the apex. A rounded posterolateral marginal elevation is present on the declivity from apex to near the base. Declivity narrowly concave in center of declivity between interstria 3, narrowed posteriorly. Strial punctures present on declivital face, surface dull. Three acute denticles are present on rounded declivital margin, one near base on interstria 3 and a pair of closely spaced denticles closer to elytral apex. Male. Unknown. Type Material. Holotype, female, Brazil: Amapá, Tartarugalzinho, Comunidade Entre Rios— Projeto de Assentamento Cedro, Retiro Paraíba, 17′32″ N, 5118′34″ W, 22–VIII–2015, FIT with ethanol, Amazonian terra firme forest fragment, W.R. Silva (MEFEIS). Distribution. Lower Amazonian region (Fig. 12F). Etymology. This species is named in honor of Jos Luiz da Silva Maia, head of the Division of Forest Protection and Environment of the forest company Duraflora in Agudos, state of São Paulo, where he worked for many years. He worked collaboratively with the second author in Scolytinae research projects over many years.Published as part of Atkinson, Thomas H., Flechtmann, Carlos A. H. & Petrov, Alexander V., 2023, Synopsis of the Neotropical Premnobiina (Coleoptera: Curculonidae: Scolytinae Ipini) with descriptions of new species, new synonymy and keys to species, pp. 69-91 in Zootaxa 5249 (1) on page 84, DOI: 10.11646/zootaxa.5249.1.4, http://zenodo.org/record/768531
TIME EVOLUTION OF SHORT-LIVED MOLECULAR SPECIES OBSERVED BY INTRACAVITY LASER ABSORPTION SPECTROSCOPY
No full textAuthor Institution: Laboratoire de Spectcometrie Physique Universite Scientifique et Medicale de Grenoble BP68 38042, Saint Martin d'Heres; Department of Chemistry, Davidson College, Davidson; Department of Chemistry, Syracuse University SyracuseWe report the feasibility of using CW intracavity laser absorption spectroscopy (ICLAS) as a probe in detecting transient species generated by pulsed laser photolysis. The method of detection uses a time-generated CW laser beam and time-resolved spectra which are delayed with respect to the photolysis pulse. Variable time delays and a constant generation time have been used to detect the time dependence of the absorbing species at times as short as a few microseconds. We applied the technique to the study of the time evolution of the formation of the free radical HCO generated by photolysis of gas-phase acetaldehyde at pressures down to tens of mtorr. We have also found that the ultimate sensitivity of the ICLAS technique is limited mainly by the mechanical stability of the cavity. M. Chenevier, M. A. Melieres, F. Stoeckel, to be published G. H. Atkinson, A. H. Laufer and M. J. Kurylo, J. Chem. Phys. 59 (1973) 350. G. H. Atkinson, T. M. Heimlich and M. W. Schuyler, J. Chem. Phys. 66 (1977 5005. A. J. Gill and G. H. Atkinson, Chem. Phys. Letters, 64 (1979) 426. R, J. Gill, W. D. Johnson and G. H. Atkinson, Chem. Phys. 58 (1981) 29
A comparative analysis of the effectiveness of selected variables from two preschool program models for children with developmental delays, 1975
No full textAmerican education is committed to the development of the indi-vidual; and one of the responsibilities the country has accepted in ful-filling this commitment is that of free public education for all children of all people. It is, therefore, from the framework of America's professed commit-ment as set forth in its goals of education: self realization, human relationships, effective citizenship, and economic efficiency that the defense for a downward extension of free public education to include early childhood education is supported. The purpose of this study was to investigate the effect of the Center Based and Home Based Parent Training Models on the selected vari-ables: developmental gains of children, parent involvement, adminis�tration, and cost-effectiveness; and the relationship of these variables to the growth gains of focal children. The experimental method of research was used in this study. The procedures used to obtain data for this research report were: (1) To test the null hypotheses that there are no significant differences between the developmental gains of randomly selected subjects in the two experi�mental programs; and between each experimental group and the randomly selected subjects in the control group. (2) To analyze the Quarterly Evaluation Reports of the Regional Evaluation Team for each project under the headings: Administration, Parent Involvement and Budget. Selected Findings 1. There was a significant difference between the growth gains of focal children enrolled in the Home Based Parent Training Program as against the focal children enrolled in the Center Based Program in com-munication skills. 2. There were significant differences between each experimental group and the control group in the five areas of growth and development identified in the study. 3. The administration of the projects was given low priority in the Quarterly Evaluation Reports. The Parent Child Center administrator was cited as 'above average' in the Parent Child Center Evaluation Report, but administration was not mentioned in the Home Based Parent Training Quarterly Evaluation Reports. 4. Since parent participation was part of the selection criteria, the parents were actively involved in both of the experimental programs. The data from the Parent Response Forms indicated that eighty-eight per�cent (88) of the Center Based parents, and one hundred percent (100) of the Home Based parents would continue to teach their children a period each day if the projects were discontinued. 5. An analysis of the budgets showed that there was a cost differ-ence of 270.00 per child and 155.00 6. There tended to be a relationship between the variables: admin-istrative process and parent involvement as evidenced by the growth gains of the focal children enrolled in the experimental programs. Conclusions There were no significant differences between the two delivery systems for children with developmental delays except in the area of communication skills. Comparisons of the experimental group with the control group indicated that early intervention can accelerate learning. The parents involved in the experimental programs understood the projects* philosophy, goals and objectives. Parents were positive in their attitudes toward their project. The capable administration (management) of the projects assured the public that the services for which the programs were designed were delivered in a manner that stimulated growth for the program participants and its personnel. The study pointed out that the needs of focal children with develop-mental delays are many, but to meet these needs, careful-attention must be given to purpose (overall growth and development) administration, parent participation, and cost-effectiveness to gather the information necessary for future planning of early intervention programs
The present status of coliege programs for the training of negro teachers of health, physical education and recreation, 1959
No full textSearch for Diboson resonances in 8 tev and 13 tev proton-proton collisions at the large hadron collider with the atlas detector
No full textThis thesis documents two searches for Diboson Resonances which were performed using data collected in 2012, 2015 and 2016 by the ATLAS detector at the Large Hadron Collider. Three benchmark models are tested: a model predicting the existence of a new heavy scalar singlet, a simplified model predicting a heavy vector-boson triplet (V ′), and a bulk Randall-Sundrum model with a heavy spin-2 graviton (G∗). Neither of these searches found evidence of any resonance, and exclusion limits are set on σ(pp → V ′) and σ(pp → G∗).
For the 2012 ATLAS data, searches are performed for the G∗ and the W′. The sample corresponds to an integrated luminosity of 20.3 fb−1 proton-proton collisions with a center of mass energy √s = 8 TeV. This search looks for the decay channels G∗ → WW → lνjj and W′ → WZ → lνjj. No evidence for resonant diboson production is observed, and resonance masses below 760 GeV and 1490 GeV are excluded at 95% confidence level for the spin-2 Randall–Sundrum bulk graviton G∗ and the spin-1 extended gauge model W′ boson respectively.
For the 2015 and 2016 ATLAS data, searches are performed for the G∗ and the V ′ and a heavy scalar. The sample corresponds to an integrated luminosity of 36.1 fb−1 proton-proton collisions with a center of mass energy √s = 13 TeV. This search looks for the decay channels G∗ → V V , scalar → V V and V ′ → V V/V H/dilepton. The V V and V H dibosons then decay into qqqq, ννqq, lνqq, llqq, lνlν, llνν, lνll, llll, qqbb, ννbb, lνbb, or llbb which are all combined (14 channels). No evidence for resonant diboson production is observed, and resonance masses below 2300 GeV are excluded at 95% confidence level for the spin-2 Randall–Sundrum bulk graviton G∗. Resonance masses below 5500 GeV and 4500 GeV are excluded at 95% confidence level for the heavy vector triplet in a weakly coupled scenario and a strongly coupled scenario respectively. No limits are extracted for the heavy scalar.Submission published under a 24 month embargo labeled 'U of I Access', the embargo will last until 2021-08-01The student, Markus Atkinson, accepted the attached license on 2019-07-04 at 17:54.The student, Markus Atkinson, submitted this Dissertation for approval on 2019-07-04 at 18:07.This Dissertation was approved for publication on 2019-07-05 at 16:01.DSpace SAF Submission Ingestion Package generated from Vireo submission #14175 on 2019-11-26 at 13:04:28Made available in DSpace on 2019-11-26T20:49:21Z (GMT). No. of bitstreams: 3
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TIME-RESOLVED RESONANCE RAMAN () SPECTROSCOPY
No full textR. B. Srivastava, M. W. Schuyler, L. R. Dosser, F. J. Purcell and G. H. Atkinson (submitted to Chem, Phys. Letters). This work was supported by the NSF.""Author Institution: Department of Chemistry, Syracuse UniversityExperimental techniques designed to obtain resonance Raman spectra of short-lived intermediates during photolytically-induced reactions will be described. These methods use high peak power ( 1 MW), pulsed laser excitation to generate Raman scattering and intensified vidicons as multi-wavelength detectors. The time resolution available extends from to several seconds. Studies of labile biophysical systems (oxyhemoglobin and cytochrome c) have demonstrated that resonance Raman spectra obtained with such high peak-power excitation exhibit no saturation or denaturation Results on the reaction intermediates in the ligation of hemoglobin and the oxidative photocyclization of substituted amines to carbazoles will be presented to illustrate the capabilities of these techniques
Cultura serrana mestiza. Una práctica de campo dirigida en la Sierra Madre Occidental. 100 (2008) octubre. Diario de Campo. Boletín interno de los investigadores del área de Antropología
No full textHAMMERSLEY, Martyn y Paul Atkinson, Etnografía. Métodos de investigación, Paidós, Barcelona, 2005.LÉVl -STRAUSS, Claude, La vía de las máscaras, Siglo XXI, México, D.F., 1997 [1979).OSEGUERA, Andrés " Rituales y evocaciones entre los pimas de la sierra Madre Occidental", Dimensión Antropológica, Instituto Nacional de Antropología e Historia, 2008, en prensa.RIVERS, W. H. R., Kinship and Social Organization, London School of Economics, Monographs on Social Anthropology, Nº 34 ([1914) 1968)
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