1,667 research outputs found
The fiction of telling: working in the potential space of reading and teaching
The North Carolina Standard Course of Study can be conceptualized as a grid of objectives and expectations within which the daily work of public school teachers takes place. Overlaying this grid on the high school literature curriculum is much like overlaying a grid on a topographical map: the grid defines both itself and the spaces between its lines. But the map is never the territory. Part of a teacher's work is navigating the interstices of the grid - figuring out what really exists on the actual ground between the lines and deciding how best to traverse that terrain with her students as it becomes visible. This study explores the energies that reading activates in students' and teachers' private selves and the relationship between those private experiences and the public ones they have when they "talk about the reading" in their classrooms. It also explores the choices literature teachers make when they teach reading. What is the role of high school literature teachers' "off the grid" lives in their "on the grid" practice of reading books with students? The study's principal data are conversations with three English teachers from three public high schools in North Carolina. The diverse literatures of psychoanalysis, social theory, reader response theory, performance theory, and teacher autobiography are explored as hermeneutic lenses. The concept of jouissance helps explicate both the role of pleasure in the classroom and its unique relationship with text. The tension between "complicated" and "complex" understandings of language, the liminal and performative aspects of pedagogical choices, and the relationships of teachers to their institutional authority (here posited as "complicity") are also explored. The educative opportunities that exist in these "potential spaces" are revealed to have profound implications for preservice and inservice teacher education as well as larger policy issues
Photorespiration: metabolic pathways and their role in stress protection
Photorespiration results from the oxygenase reaction catalysed by ribulose-1,5-bisphosphate carboxylase/
oxygenase. In this reaction glycollate-2-phosphate is produced and subsequently metabolized in the
photorespiratory pathway to form the Calvin cycle intermediate glycerate-3-phosphate. During this metabolic
process, CO2 and NH3 are produced and ATP and reducing equivalents are consumed, thus
making photorespiration a wasteful process. However, precisely because of this ine€ciency, photorespiration
could serve as an energy sink preventing the overreduction of the photosynthetic electron transport
chain and photoinhibition, especially under stress conditions that lead to reduced rates of photosynthetic
CO2 assimilation. Furthermore, photorespiration provides metabolites for other metabolic processes, e.g.
glycine for the synthesis of glutathione, which is also involved in stress protection. In this review, we
describe the use of photorespiratory mutants to study the control and regulation of photorespiratory pathways.
In addition, we discuss the possible role of photorespiration under stress conditions, such as
drought, high salt concentrations and high light intensities encountered by alpine plants
Renal ganglioneuromas in a pediatric patient: Case report and review of the literature
AbstractGanglioneuromas are rare benign tumors originating from the sympathetic nervous system and neural crest cells. A 4-year-old girl presented with numerous urinary tract infections. Ultrasound and computed tomography revealed a large mass within the right kidney. A right nephrectomy and sampling of surrounding lymph nodes were performed. Pathology confirmed that the mass was a mature ganglioneuroma. The patient remains disease-free, more than 2 years after surgery. We present this rare case of renal ganglioneuroma as well as a review of the literature
Can rates of ocean primary production and biological carbon export be related through their probability distributions?
© The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Global Biogeochemical Cycles 32 (2018): 954-970, doi:10.1029/2017GB005797.We describe the basis of a theory for interpreting measurements of two key biogeochemical fluxesâprimary production by phytoplankton (p, ÎŒg C · Lâ1 · dayâ1) and biological carbon export from the surface ocean by sinking particles (f, mg C · mâ2 · dayâ1)âin terms of their probability distributions. Given that p and f are mechanistically linked but variable and effectively measured on different scales, we hypothesize that a quantitative relationship emerges between collections of the two measurements. Motivated by the many subprocesses driving production and export, we take as a null model that largeâscale distributions of p and f are lognormal. We then show that compilations of p and f measurements are consistent with this hypothesis. The compilation of p measurements is extensive enough to subregion by biome, basin, depth, or season; these subsets are also well described by lognormals, whose logâmoments sort predictably. Informed by the lognormality of both p and f we infer a statistical scaling relationship between the two quantities and derive a linear relationship between the logâmoments of their distributions. We find agreement between two independent estimates of the slope and intercept of this line and show that the distribution of f measurements is consistent with predictions made from the moments of the p distribution. These results illustrate the utility of a distributional approach to biogeochemical fluxes. We close by describing potential uses and challenges for the further development of such an approach.National Science Foundation Grant Number: OCE-1315201;
Simons Foundation Grant Numbers: 329108, 553242;
National Aeronautics and Space Administration Grant Numbers: NNX16AR47G, NNX16AR49
Transgenic camelina oil is an effective source of eicosapentaenoic acid and docosahexaenoic acid in diets for farmed rainbow trout, in terms of growth, tissue fatty acid content, and fillet sensory properties
The oilseed Camelina sativa was genetically engineered to produce eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) at levels similar to fish oil (FO), which we tested as a lipid source in diets for rainbow trout. Three experimental diets were tested, a FO control, a lowâlevel transgenic camelina oil (LCO) diet (no FO with 12.5 g/kg camelina), and a highâlevel transgenic camelina oil (HCO) diet (no FO with 130âg/kg transgenic camelina). Trout (initial weight 49.8â±â11âg/fish) were fed for 12âweeks and were evaluated for growth performance, fatty acid content (muscle, liver, brain, and eye), and sensory properties of fillets. The final lengths and weights of fish fed LCO and HCO diets were higher compared to fish fed FO. There were no differences in weight gain, condition factor, specific growth rate, feed intake, and feed conversion ratio. EPA in muscle tissue was higher in fish fed HCO and FO diets compared to the LCO diet. Compoundâspecific stable isotope analysis revealed that rainbow trout fed the FO diet stored isotopically enriched DHA compared to the lighter DHA in fish fed HCO. Trout fillets from the HCO treatment were firmer in texture and had a higher orange intensity compared to the FO group
Behaviour of uranium along Jucar River (Eastern Spain) Determination of 234U/238U and 235U/238U ratios
The uranium concentration and the U-234/U-238, U-235/U-238 activity ratios were studied in water samples from Jucar River, using low-level alpha-spectrometry. The effects of pH, temperature and salinity were considered and more detailed sampling was done in the neighbourhood of Cofrentes Nuclear plant (Valencia, Spain). Changes were observed in the uranium concentration with the salinity and the U-234/U-238 activity ratio was found to vary with pH. Leaching and dilution, which depend on pH and salinity, are the probable mechanisms for these changes in the concentration of uranium and the activity ratios.RodrĂguez Ălvarez, MJ.; Sanchez, F. (1995). Behaviour of uranium along Jucar River (Eastern Spain) Determination of 234U/238U and 235U/238U ratios. Journal of Radioanalytical and Nuclear Chemistry. 190(1):113-120. doi:10.1007/BF02035642S1131201901M. J. RORDĂGUEZ-AALVAREZ, F. SĂNCHEZ, E. NAVARRO, Proc. 3nd Intern. Summer School, Huelva Spain, M. GARCĂA-LEĂN, G. MADURGA (Eds), World Scientific, Singapore, 1994.M. IVANOVICH, R. S. HARMON (Eds), Uranium Disequilibrium Series: Applications to Environmental Problems, Clarendon Press, Oxford, 1982.K. OSMOND, J. B. COWART, At. Energy Rev., 14 (1976) 621.B. L. DICKSON, R. L. MEAKINS, Nucl. Instrum. Methods Phys. Res., 223 (1983) 593.J. L. GASCĂN, MURILLO, PhD Thesis, University of Zaragoza, Spain, 1990.M. C. MORĂN, A. MARTINEZ-AGUIRRE, M. GARCĂA-LEĂN, Intern. Conf. on Environmental Radioactivity in the Mediterranean Area, Barcelona 10â13 May 1988, SNE-ENS, Barcelona, 1988, p. 111.R. BOJANOWSKI, R. FUKAI, S. BALLESTRA, H. ASARI, Determination of natural radioactive elements in marine environmental materials by ion-exchange and α-spectrometry. Proc. 4th Symp. on the Determination of Radionuclides in Environmental and Biological Materials, April 1983, London, Ed-Rd Press.R. GARCĂA-TENORIO, M. GARCĂA-LEĂN, G. PIAZZA, Anal. FĂsica B, 82 (1986) 238.L. HALLSTADIUS, Nucl. Instrum. Methods Phys. Res., 223 (1984) 266.F. VERA, A. MARTIN, Nucl. Instrum. Methods Phys. Res., A276 (1989) 289.A. MARTINEZ-AGUIRRE, M. GARCĂA-LEĂN, J. Radioanal. Nucl. Chem., 155 (1991) 97.J. R. DOOLEY, H. C. ROSHOLT, Econ. Geol., 61 (1996) 326.A. MARTINEZ-AGUIRRE, M. GARCĂA-LEĂN, Radiat. Prot. Dosim., 45 (1992) 249.J. TOOLE, M. S. BAXTER, J. THOMSON, Estuarine, Coastal and Shelf Sci., 25 (1987) 283.S. G. BHAT, S. KRISHANASWAMI, Proc. Indian Acad. Sci., A LXX, (1969).K. K. TUREKIAN, J. K. COCHRAN, in: Chemical Oceanography, Vol. 7, J. P. RILEY and R. CHESTER (Eds), 2nd ed., Academic Press, New York, 1978.D. LANGMUIR, Geochim. Cosmochim. Acta, 42 (1978) 547.J. M. MARTIN, M. MEYBECK, Mar. Chem., 7 (1979) 173.Radionuclide Transformations, Annals of the ICRP, ICRP Publication 38, Vol. 11â13, Pergamon Press, 1983.A. MANGINI, G. SONNTAG, G. BERTSCH, E. MĂLLER, Nature, 278 (1979) 337.M. R. SCOTT, in: M. IVANOVICH, R. S. HARMON (Eds), Uranium Disequilibrium Series: Applications to Environmental Problems, Clarendon Press, Oxford, 1982.J. K. OSMOND, J. B. COWART, in: M. IVANOVICH, R. S. HARMON (Eds), Uranium Disequilibrium Series: Applications to Environmental Problems, Clarendon Press, Oxford, 1982.R. BOWEN (Eds), Isotopes in the Earth Sciences, Elsevier Applied Science, 1988.F. VERA, PhD Thesis, University Extremadura, Spain, 1988.F. VERA, A. MARTIN, J. Radioanal. Nucl. Chem., 134 (1988) 73
A statistical analysis of the Two Dimensional XMM-Newton Group Survey: The impact of feedback on group properties
(abridged) We present a statistical analysis of 28 nearby galaxy groups from
the Two-Dimensional XMM-Newton Group Survey (2dXGS). We focus on entropy and
the role of feedback, dividing the sample into cool core (CC) and non cool core
(NCC) systems, the first time the latter have been studied in detail in the
group regime. The coolest groups have steeper entropy profiles than the warmest
systems, and NCC groups have higher central entropy and exhibit more scatter
than their CC counterparts. We compare the entropy distribution of the gas in
each system to the expected theoretical distribution ignoring non-gravitational
processes. In all cases, the observed maximum entropy far exceeds that expected
theoretically, and simple models for modifications of the theoretical entropy
distribution perform poorly. Applying initial pre-heating, followed by
radiative cooling, generally fails to match the low entropy behaviour, and only
performs well when the difference between the maximum entropy of the observed
and theoretical distributions is small. Successful feedback models need to work
differentially to increase the entropy range in the gas, and we suggest two
basic possibilities. We analyse the effects of feedback on the entropy
distribution, finding systems with a high measure of `feedback impact' to reach
higher entropy than their low feedback counterparts and also to show
significantly lower central metallicities. If low entropy, metal-rich gas has
been boosted to large entropy in the high feedback systems, it must now reside
outside 0.5r_500, to remain undetected. We find similar levels of enrichment in
both high and low feedback systems, and argue that the lack of extra metals in
the highest feedback systems points to an AGN origin for the bulk of the
feedback, probably acting within precursor structures.Comment: 24 pages, 21 figures; accepted for publication in MNRA
Prediction of residual stress fields after shot-peening of TRIP780 steel with second-order and artificial neural network models based on multi-impact finite element simulations
Shot-peening is a mechanical surface treatment widely employed to enhance the fatigue life of metallic components
by generating compressive residual stress fields below the surface. These fields are mainly impacted by
the selection of the process parameters. The aim of this work is to propose a hybrid approach to conduct two
predictive models: second-order model and feed-forward artificial neural network model. For this purpose, a 3D
multiple-impact finite element model coupled to a central composite design of experiments was employed. A
parametric analysis was also conducted to investigate the effect of the shot diameter, the shot velocity, the
coverage, and the impact angle on the induced residual stress profile within a TRIP780 steel. It was found that
both models predict with good agreement, the residual stress profile as a function of the process parameters and
can be used in shot-peening optimization due to their responsiveness
The duration of embryo culture after mouse IVF differentially affects cardiovascular and metabolic health in male offspring
Study question: Do the long-term health outcomes following IVF differ depending upon the duration of embryo culture before transfer?Summary answer: Using a mouse model, we demonstrate that in male but not female offspring, adverse cardiovascular (CV) health was more likely with prolonged culture to the blastocyst stage, but metabolic dysfunction was more likely if embryo transfer (ET) occurred at the early cleavage stage.What is known already: ART associate with increased risk of adverse CV and metabolic health in offspring, and these findings have been confirmed in animal models in the absence of parental infertility issues. It is unclear which specific ART treatments may cause these risks. There is increasing use of blastocyst, versus cleavage-stage, transfer in clinical ART which does not appear to impair perinatal health of children born, but the longer-term health implications are unknown.Study design, size, duration: Five mouse groups were generated comprising: (i) natural mating (NM)-naturally mated, non-superovulated and undisturbed gestation; (ii) IV-ET-2Cell-in-vivo derived two-cell embryos collected from superovulated mothers, with immediate ET to recipients; (iii) IVF-ET-2Cell-IVF generated embryos, from oocytes from superovulated mothers, cultured to the two-cell stage before ET to recipients; (iv) IV-ET-BL-in-vivo derived blastocysts collected from superovulated mothers, with immediate ET to recipients; (v) IVF-ET-BL-IVF generated embryos, from oocytes from superovulated mothers, cultured to the blastocyst stage before ET to recipients. Both male and female offspring were analysed for growth, CV and metabolic markers of health. There were 8-13 litters generated for each group for analyses; postnatal data were analysed by multilevel random effects regression to take account of between-mother and within-mother variation and litter size.Participants/materials, settings, methods: C57/BL6 female mice (3-4 weeks old) were used for oocyte production; CBA males for sperm with human tubal fluid medium were used for IVF. Embryos were transferred (ET) to MF1 pseudo-pregnant recipients at the two-cell stage or cultured in synthetic oviductal medium enriched with potassium medium to the blastocyst stage before ET. Control in-vivo embryos from C57BL6 Ă CBA matings were collected and immediately transferred at the two-cell or blastocyst stage. Postnatal assays included growth rate up to 27 weeks; systolic blood pressure (SBP) at 9, 15 and 21 weeks; lung and serum angiotensin-converting enzyme (ACE) activity at time of cull (27 weeks); glucose tolerance test (GTT; 27 weeks); basal glucose and insulin levels (27 weeks); and lipid accumulation in liver cryosections using Oil Red O imaging (27 weeks).Main results and the role of chance: Blastocysts formed by IVF developed at a slower rate and comprised fewer cells that in-vivo generated blastocysts without culture (P < 0.05). Postnatal growth rate was increased in all four experimental treatments compared with NM group (P < 0.05). SBP, serum and lung ACE and heart/body weight were higher in IVF-ET-BL versus IVF-ET-2Cell males (P < 0.05) and higher than in other treatment groups, with SBP and lung ACE positively correlated (P < 0.05). Glucose handling (GTT AUC) was poorer and basal insulin levels were higher in IVF-ET-2Cell males than in IVF-ET-BL (P < 0.05) with the glucose:insulin ratio more negatively correlated with body weight in IVF-ET-2Cell males than in other groups. Liver/body weight and liver lipid droplet diameter and density in IVF-ET-2Cell males were higher than in IVF-ET-BL males (P < 0.05). IVF groups had poorer health characteristics than their in-vivo control groups, indicating that outcomes were not caused specifically by background techniques (superovulation, ET). No consistent health effects from duration of culture were identified in female offspring.Large scale data: N/A.Limitations, reasons for caution: Results from experimental animal models cannot be extrapolated to humans. Nevertheless, they are valuable to develop conceptual models, in this case, in the absence of confounding parental infertility, in assessing the safety of ART manipulations.Wider implications of the findings: The study indicates that longer duration of embryo culture after IVF up to blastocyst before ET leads to increased dysfunction of CV health in males compared with IVF and shorter cleavage-stage ET. However, the metabolic health of male offspring was poorer after shorter versus longer culture duration. This distinction indicates that the origin of CV and metabolic health phenotypes after ART may be different. The poorer metabolic health of males after cleavage-stage ET coincides with embryonic genome activation occurring at the time of ET
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