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Physiological States (physiological + states)
Selected AbstractsYoung Children's Reasoning About the Effects of Emotional and Physiological States on Academic PerformanceCHILD DEVELOPMENT, Issue 1 2009Jennifer Amsterlaw This study assessed young children's understanding of the effects of emotional and physiological states on cognitive performance. Five, 6-, 7-year-olds, and adults (N= 96) predicted and explained how children experiencing a variety of physiological and emotional states would perform on academic tasks. Scenarios included: (a) negative and positive emotions, (b) negative and positive physiological states, and (c) control conditions. All age groups understood the impairing effects of negative emotions and physiological states. Only 7-year-olds, however, showed adult-like reasoning about the potential enhancing effects of positive internal states and routinely cited cognitive mechanisms to explain how internal states affect performance. These results shed light on theory-of-mind development and also have significance for children's everyday school success. [source] Determination of amino acids in rat vitreous perfusates by capillary electrophoresisELECTROPHORESIS, Issue 17 2004Kongthong Thongkhao-On Abstract In vivo determinations of amino acids are important for improving our understanding of physiological states of biological tissue function and dysfunction. However, the chemically complex matrix of different biological fluids complicates the assay of this important class of molecules. We introduce a method for characterizing the amino acid composition of submicroliter volumes of vitreous humor perfusates. Low-flow push-pull perfusion sampling is compatible with collecting small volume samples in a complicated matrix that are potentially difficult to separate. An efficient, sensitive, and rapid analysis of amino acids from in vivo perfusates of the vitreous is presented with 3-(4-carboxybenzoyl)-2-quinoline-carboxaldehyde (CBQCA) derivatitation and capillary electrophoresis (CE) separation with laser-induced fluorescence detection (LIF). Derivatization with CBQCA for up to 2 h provided high sensitivity and low detection limits at the nM level. Seventeen amino acids including D -serine (D -Ser) and D -aspartate (D -Asp) were resolved in less than 10 min. Importantly, D -Ser is separated from its enantiomeric pair. Characterization of vitreal amino acids with this assay technique will be useful for understanding ocular diseases and physiological mechanisms in vision. [source] Impact of surface thermodynamics on bacterial transportENVIRONMENTAL MICROBIOLOGY, Issue 4 2001Gang Chen Microbial surface thermodynamics correlated with bacterial transport in saturated porous media. The surface thermodynamics was characterized by contact-angle measurement and the wicking method, which was related to surface free energies of Lifshitz,van der Waals interaction, Lewis acid,base interaction, and electrostatic interaction between the bacteria and the medium matrix. Transport of three different strains of bacteria present at three physiological states was measured in columns of silica gel and sand from the Canadian River Alluvium (Norman, OK, USA). Microorganisms in stationary state had the highest deposit on solid matrix, compared with logarithmic and decay states. The deposition correlated with the total surface free energy (,G132TOT) and the differences in ,G132TOT were mainly controlled by the Lewis acid,base interaction. Infrared spectroscopy showed that the increased deposition correlated with an increase in the hydrogen-bonding functional groups on the cell surfaces. [source] Taurine selectively modulates the secretory activity of vasopressin neurons in conscious ratsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2001Mario Engelmann Abstract Previous experiments have shown that a 10-min forced swimming session triggers the release of vasopressin from somata and dendrites, but not axon terminals, of neurons of the hypothalamic,neurohypophysial system. To further investigate regulatory mechanisms underlying this dissociated release, we forced male Wistar rats to swim in warm (20 °C) water and monitored release of the potentially inhibitory amino acids gamma amino butyric acid (GABA) and taurine into the hypothalamic supraoptic nucleus using microdialysis. Forced swimming caused a significant increase in the release of taurine (up to 350%; P < 0.05 vs. prestress release), but not GABA. To reveal the physiological significance of centrally released taurine, the specific taurine antagonist 6-aminomethyl-3-methyl-4H-1,2,4-benzothiadiazine-1,1-dioxide was administered into the supraoptic nucleus via retrodialysis. Administration of this antagonist caused a significant increase in the release of vasopressin within the supraoptic nucleus and into the blood both under basal conditions and during stress (up to 800%; P < 0.05 vs. basal values), without affecting hypothalamic or plasma oxytocin. Local administration of the GABAA receptor antagonist bicuculline, in contrast, failed to influence vasopressin secretion at either time point. In a separate series of in vivo electrophysiological experiments, administration of the same dosage of the taurine antagonist into the supraoptic nucleus via microdialysis resulted in an increased electrical activity of identified vasopressinergic, but not oxytocinergic, neurons. Taken together our data demonstrate that taurine is released within the supraoptic nucleus during physical/emotional stress. Furthermore, at the level of the supraoptic nucleus, taurine inhibits not only the electrical activity of vasopressin neurons but also acts as an inhibitor of both central and peripheral vasopressin secretion during different physiological states. [source] Reversible transition between active and dormant microbial states in soilFEMS MICROBIOLOGY ECOLOGY, Issue 2-3 2001John Stenström Abstract The rate of respiration obtained in the substrate-induced respiration (SIR) method can be divided into the respiration rate of growing (r) and non-growing (K) microorganisms. The fraction of r is generally small (5,20%) in soils with no recent addition of substrates, but can be 100% in soils with high substrate availability. This suggests that substrate availability determines the proportion of biomass between these groups, and implies that transitions between them can take place reversibly. These hypotheses were tested by adding three different amounts of glucose which induced first-order, zero-order, and growth-associated respiration kinetics to three soils at four pre-incubation times (4, 12, 27, and 46 days) before the SIR measurement. An abiotic flush of CO2 in the SIR measurement was detected and corrected for before data analysis. Accumulated CO2 -C over 4 days after glucose addition, corrected for the respiration in unamended controls, corresponded to 41,50% mineralization of the glucose-C, and the relative amount mineralized by each soil was independent of the glucose amount added. The high glucose concentration gave an increased SIR, which reverted to the initial value within 27,46 days. In a specific sample, the maximum respiration rate induced during the pre-incubation, and the amount of organisms transformed from the K to the r state, as quantified in respiration rate units in the SIR measurement, were identical to each other, and these parameters were also highly correlated to the initial glucose concentration. The K,r transition was very fast, probably concurrent with the instantaneous increase in the respiration rate obtained by the glucose amendment. Thereafter, a slow first-order back-transition from the r to the K state ensued, with half-lives of 12, 23, and 70 days for the three soils. The results suggest the existence of community-level controls by which growth within or of the whole biomass is inhibited until it has been completely transformed into the r state. The data also suggest that the microbial specific activity is not related to the availability of exogenous substrate in a continuous fashion, rather it responds as a sharp transition between dormant and fully active. Furthermore, the inherent physiological state of the microbial biomass is strongly related to its history. It is proposed that the normal dynamics of the soil microbial biomass is an oscillation between active and dormant physiological states, while significant growth occurs only at substantial substrate amendment. [source] Estimating fat and protein fuel from fat and muscle scores in passerinesIBIS, Issue 4 2009VOLKER SALEWSKI Fat is the prime energy source for birds during prolonged exercise, but protein is also catabolized. Estimates of the amount of catabolizable fat and protein (termed fat and protein fuel) are therefore important for studying energetics of birds. As fat and protein fuel can only be measured by sacrificing individuals or by use of technically complex methods, scoring systems were invented to estimate fat and protein fuel of birds in the field. The visible subcutaneous fat deposits and the thickness of the flight muscles are each scored on an ordinal scale but these scales do not correspond linearly to fat and protein fuel within species, which is needed for analyses such as flight range estimates. We developed an anova -type model to estimate fat and protein fuel from fat scores (FS) and muscle scores (MS) along with total mass and a size measurement. Using data from 11 337 individuals of eight passerine species (Common Nightingale Luscinia megarhynchos, Eurasian Reed Warbler Acrocephalus scirpaceus, Melodious Warbler Hippolais polyglotta, Willow Warbler Phylloscopus trochilus, Orphean Warbler Sylvia hortensis, Garden Warbler Sylvia borin, Common Whitethroat Sylvia communis, Subalpine Warbler Sylvia cantillans) mist-netted in Mauritania, West Africa, we tested for independence of FS and MS and for variation in the relationship between scores and associated mass in response to physiological state. FS, MS and third primary length (size) explained variation in body mass of all eight species analysed (R2: 0.56,0.77). The parameter estimates of the model showed that fat and protein fuel increased monotonically with increasing fat and muscle scores. In two species we found small differences in the estimates between physiological states (seasons). We evaluated our model by comparing the predicted body mass of birds with both FS and MS equal to 0 with the mean body mass of individuals mist-netted with both scores equal to zero. The values were very close. The amount of fat extracted from dead Garden and Willow Warblers was within the range of predicted fat fuel derived from the model. We conclude that our model is a useful non-invasive method to estimate simultaneously mean fat and protein fuel of small passerines and we provide recommendations on its use. [source] Regional climate modulates the canopy mosaic of favourable and risky microclimates for insectsJOURNAL OF ANIMAL ECOLOGY, Issue 3 2007SYLVAIN PINCEBOURDE Summary 1,One major gap in our ability to predict the impacts of climate change is a quantitative analysis of temperatures experienced by organisms under natural conditions. We developed a framework to describe and quantify the impacts of local climate on the mosaic of microclimates and physiological states of insects within tree canopies. This approach was applied to a leaf mining moth feeding on apple leaf tissues. 2,Canopy geometry was explicitly considered by mapping the 3D position and orientation of more than 26 000 leaves in an apple tree. Four published models for canopy radiation interception, energy budget of leaves and mines, body temperature and developmental rate of the leaf miner were integrated. Model predictions were compared with actual microclimate temperatures. The biophysical model accurately predicted temperature within mines at different positions within the tree crown. 3,Field temperature measurements indicated that leaf and mine temperature patterns differ according to the regional climatic conditions (cloudy or sunny) and depending on their location within the canopy. Mines in the sun can be warmer than those in the shade by several degrees and the heterogeneity of mine temperature was incremented by 120%, compared with that of leaf temperature. 4.,The integrated model was used to explore the impact of both warm and exceptionally hot climatic conditions recorded during a heat wave on the microclimate heterogeneity at canopy scale. During warm conditions, larvae in sunlight-exposed mines experienced nearly optimal growth conditions compared with those within shaded mines. The developmental rate was increased by almost 50% in the sunny microhabitat compared with the shaded location. Larvae, however, experienced optimal temperatures for their development inside shaded mines during extreme climatic conditions, whereas larvae in exposed mines were overheating, leading to major risks of mortality. 5,Tree canopies act as both magnifiers and reducers of the climatic regime experienced in open air outside canopies. Favourable and risky spots within the canopy do change as a function of the climatic conditions at the regional scale. The shifting nature of the mosaic of suitable and risky habitats may explain the observed uniform distribution of leaf miners within tree canopies. [source] Weakly aggressive behaviour towards nymphs in the cockroach Schultesia nitor (Blattaria: Zetoborinae)AGGRESSIVE BEHAVIOR, Issue 6 2007Joan Van Baaren Abstract This paper describes aggressive behaviour in the cockroach Schultesia nitor, a tropical forest species living in bird nests. Young S. nitor nymphs are known to show active dispersal while old nymphs and adults are contrastingly strongly gregarious, a combination of features never observed in other cockroach species. Our laboratory experiments using video recording of confrontations between pairs show that aggressive behaviour towards conspecific nymphs is not exhibited towards nymphs of the species Phoetalia pallida, and thus can be considered species specific in S. nitor. But, it is not kin oriented: the mother and all adults of both sexes in different physiological states exhibit this behaviour as well. Six types of aggressive interactions were discriminated, occurring in age-symmetric pairs of nymphs and adults. Even more frequent aggression was exhibited by adults and last instar nymphs towards younger nymphs of all instars. The frequency of aggressive acts and types of aggressive interactions varied according to sex and size of the two interacting individuals. The possible function and evolution of this behaviour is discussed, with emphasis on the difficulty of interpreting obvious but weak and not kin-biased aggression. Aggr. Behav. 33:498,507, 2007. © 2007 Wiley-Liss, Inc. [source] Lifespan extension by conditions that inhibit translation in Caenorhabditis elegansAGING CELL, Issue 1 2007Malene Hansen Summary Many conditions that shift cells from states of nutrient utilization and growth to states of cell maintenance extend lifespan. We have carried out a systematic lifespan analysis of conditions that inhibit protein synthesis. We find that reducing the levels of ribosomal proteins, ribosomal-protein S6 kinase or translation-initiation factors increases the lifespan of Caenorhabditis elegans. These perturbations, as well as inhibition of the nutrient sensor target of rapamycin (TOR), which is known to increase lifespan, all increase thermal-stress resistance. Thus inhibiting translation may extend lifespan by shifting cells to physiological states that favor maintenance and repair. Interestingly, different types of translation inhibition lead to one of two mutually exclusive outputs, one that increases lifespan and stress resistance through the transcription factor DAF-16/FOXO, and one that increases lifespan and stress resistance independently of DAF-16. Our findings link TOR, but not sir-2.1, to the longevity response induced by dietary restriction (DR) in C. elegans, and they suggest that neither TOR inhibition nor DR extends lifespan simply by reducing protein synthesis. [source] Metabotropic Glutamate Receptors: Gatekeepers of HomeostasisJOURNAL OF NEUROENDOCRINOLOGY, Issue 7 2010J. B. Kuzmiski The capacity to appropriately respond to physiological challenges or perturbations in homeostasis is a requisite for survival. It is becoming increasingly clear that long-lasting alterations in synaptic efficacy are a fundamental mechanism for modifying neuroendocrine and autonomic output. We review recent advances in our understanding of plasticity at glutamate synapses onto magnocellular neurones (MNCs) in the paraventricular and supraoptic nuclei of the hypothalamus, with a focus on the contributions of metabotropic glutamate receptors (mGluRs) to long-lasting modifications in synaptic efficacy. Special attention is paid to the role of presynaptic mGluRs as gatekeepers for metaplasticity and regulation of body fluid homeostasis. The work highlighted here provides insight into the synaptic mechanisms that couple MNC activity to physiological states. [source] The Adaptive Brain: Glenn Hatton and the Supraoptic NucleusJOURNAL OF NEUROENDOCRINOLOGY, Issue 5 2010G. Leng In December 2009, Glenn Hatton died, and neuroendocrinology lost a pioneer who had done much to forge our present understanding of the hypothalamus and whose productivity had not faded with the passing years. Glenn, an expert in both functional morphology and electrophysiology, was driven by a will to understand the significance of his observations in the context of the living, behaving organism. He also had the wit to generate bold and challenging hypotheses, the wherewithal to expose them to critical and elegant experimental testing, and a way with words that gave his papers and lectures clarity and eloquence. The hypothalamo-neurohypophysial system offered a host of opportunities for understanding how physiological functions are fulfilled by the electrical activity of neurones, how neuronal behaviour changes with changing physiological states, and how morphological changes contribute to the physiological response. In the vision that Glenn developed over 35 years, the neuroendocrine brain is as dynamic in structure as it is adaptable in function. Its adaptability is reflected not only by mere synaptic plasticity, but also by changes in neuronal morphology and in the morphology of the glial cells. Astrocytes, in Glenn's view, were intimate partners of the neurones, partners with an essential role in adaptation to changing physiological demands. [source] Patient variation in veterinary medicine: part I. Influence of altered physiological statesJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 3 2010M. MARTINEZ Martinez, M., Modric, S. Patient variation in veterinary medicine: part I. Influence of altered physiological states. J. vet. Pharmacol. Therap.33, 213,226. In veterinary medicine, the characterization of a drug's pharmacokinetic (PK) properties is generally based upon data that are derived from studies that employ small groups of young healthy animals, often of a single breed. These are also the data from which population predictions are often generated to forecast drug exposure characteristics in the target population under clinical conditions of use. In veterinary medicine, it is rare to find information on the covariates that can influence drug exposure characteristics. Therefore, it is important to recognize some of the factors that can alter the outcome of PK studies and therefore potentially alter the pharmacological response. Some of these factors are easily identified, such as breed, gender, age, and body weight. Others are less obvious, such as disease, heritable traits, and environmental factors. This manuscript provides an overview of the various stressors (such as disease, inflammation, pregnancy, and lactation) that can substantially alter drug PK. Part II of this series provides an overview of the potential impact of physiological variables such as age, weight, and heritable traits, on drug PK. Ultimately, failure to identify appropriate covariates can lead to substantial error when predicting the dose,exposure relationship within a population. [source] The lobular expression of the rat asialoglycoprotein receptor is regulated at the posttranscriptional levelLIVER INTERNATIONAL, Issue 1 2005Mara Massimi Abstract: The purpose of this study was to define the distribution of the asialoglycoprotein receptor (ASGP-R) main peptide, rat hepatic lectin (RHL)-1, within the rat liver lobule and to investigate its possible modulation in physiological states characterised by marked changes of receptorial expression. In particular, we chose livers from rats partially hepatectomised or at the end of pregnancy, as models, respectively, of decreased or increased expression of the ASGP-R, and used the in situ hybridisation and immunocytochemistry techniques to analyse in parallel the lobular distributions of RHL-1 mRNA and protein. In normal rat liver, although the RHL-1 mRNA was homogeneously distributed, the RHL-1 peptide was predominantly localised on the surface of pericentral hepatocytes with a gradient of expression towards the periportal zone. This gradient of expression of RHL-1 peptide was reduced in regenerating livers, in which the positive stain was restricted to a few layers of cells around the central vein. In contrast, livers at the end of pregnancy showed an overall increase of the peptide with a concomitant flattening of the gradient across the liver plate. In all the conditions, we never observed important changes in the pattern of expression of the specific mRNA. These findings indicate that the distribution of ASGP-R is heterogeneous across the liver lobule, with a pattern of expression prevalently modulated at the posttranscriptional level. [source] What Are Emotions About?PHILOSOPHY AND PHENOMENOLOGICAL RESEARCH, Issue 2 2003LILLI ALANEN This paper discusses the interrelations between three aspects of human emotions: their intentionality, their expressivity and their moral significance. It distinguishes three kinds of philosophical views of emotions: the cognitivist (classically held by the Stoics), the emotivist which reduces emotions to non-intentional bodily sensations and physiological states, and the moral phenomenologist, the latter being held by Annette Baier, whose work is the focus of the discussion. Her view, which represents an original development of ideas found in Descartes and Hume, avoids the reductionism of congitivist and emotivist accounts. The paper gives special attention to her notion of ,deep'objects of emotions and to her account of the expressivity of emotions, arguing that while the first is problematic, the second is a significant contribution to our understanding of the role of emotions in our moral lives. [source] A qualitative proteome investigation of the sediment portion of human urine: Implications in the biomarker discovery processPROTEOMICS - CLINICAL APPLICATIONS, Issue 1 2009Diane Mataija-Botelho Abstract Inherent to the biomarker discovery process is a comparative analysis of physiological states. It is therefore critical that the proteome detection protocol does not bias the analysis. With urine, the sediment portion, obtained upon thawing frozen urine, is routinely discarded prior to proteome analysis. However, our results demonstrate that such a practice inadvertently induces bias, having significant implications in the biomarker discovery process. We present the first proteome investigation of human urinary sediments, identifying 60 proteins in this phase by MS. Many sediment proteins were also detected in the urinary supernatant, indicating that several proteins partition between the two phases. This partitioning is dependant on the pH of the sample, as well as the degree of sample agitation. As a consequence of discarding the sediment portion of urine, the concentration of potential candidate biomarkers in the supernatant phase will be altered or, in other instances, may be completely removed from the sample. To minimize this, the pH of all samples should first be normalized, and the samples vigorously vortexed prior to discarding the sediments. For more comprehensive biomarker investigations, we suggest that urinary sediments be analyzed along with the supernatant proteins. [source] Natural intramolecular isotope measurements in physiology: elements of the case for an effort toward high-precision position-specific isotope analysis,RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 15 2001J. T. Brenna Chemical information available in organisms can be categorized into three major domains, macromolecular, small molecules, and isotope ratios. Information about physiological state is commonly obtained by qualitative and quantitative analysis in the macromolecular and small molecule domains. Genomics and proteomics are emerging approaches to analysis of macromolecules, and both areas yield definitive information on present physiological state. There is relatively little record of past physiological states of the individual available in these domains. Natural isotopic variability, particularly on an intramolecular level, is likely to retain more physiological history. Because of ubiquitous isotopic fractionation, every stereochemically unique position in every molecule has an isotope ratio that reflects the processes of synthesis and degradation. This fact highlights a vast amount of organismal chemical information that is essentially unstudied. Isotope measurements can be classified according to the chemical complexity of the analyte into bulk, compound-specific, and position-specific or intramolecular levels. Recent advances in analysis of isotope ratios are transforming natural science, and particularly answering questions about ecosystems using bulk methods; however, they have had relatively little impact on physiology. This may be because the vast complexities of physiological questions demand very selective information available in position-specific isotope analysis (PSIA). The relatively few high-precision PSIA studies, based on isotope ratio mass spectrometry (IRMS), have revealed intramolecular isotope ratio differences in pivotal physiological compounds including amino acids, glucose, glycerol, acetate, fatty acids, and purines. The majority of these analyses have been accomplished by laborious offline methods; however, recent advances in instrumentation presage rapid PSIA that will be necessary to attack real physiological problems. Gas-phase pyrolysis has been shown to be an effective method to determine 13C/12C at high precision for molecular fragments, and technologies to extend C-based PSIA to N and other organic elements are emerging. Two related efforts are warranted, (a) development of rapid, convenient, and sensitive methods for high-precision PSIA, a necessary precursor to (b) a concerted investigation into the relationship of metabolic state to intramolecular isotope ratio. Inherent in this latter goal is the need to identify long-lived molecules in long-lived cells that retain a record of early isotopic conditions, as has been shown for post-mortem human neuronal DNA. Using known metabolic precursor-product relationships between intramolecular positions, future studies of physiological isotope fractionation should reveal the relationship of diet and environment to observed isotope ratio. This science of isotope physiology, or simply isotopics, should add an important tool for elucidation of early factors that effect later health, probably the most difficult class of biomedical issues. Copyright © 2001 John Wiley & Sons, Ltd. [source] Uterine blood flow responses to ICI 182 780 in ovariectomized oestradiol-17,-treated, intact follicular and pregnant sheepTHE JOURNAL OF PHYSIOLOGY, Issue 1 2005Ronald R. Magness Oestrogen dramatically increases uterine blood flow (UBF) in ovariectomized (Ovx) ewes. Both the follicular phase and pregnancy are normal physiological states with elevated levels of circulating oestrogen. ICI 182 780 is a pure steroidal oestrogen receptor (ER) antagonist that blocks oestrogenic actions in oestrogen-responsive tissue. We hypothesized that an ER-mediated mechanism is responsible for in vivo rises in UBF in physiological states of high oestrogen. The purpose of the study was to examine the effect of an ER antagonist on exogenous and endogenous oestradiol-17, (E2,)-mediated elevations in UBF. Sheep were surgically instrumented with bilateral uterine artery blood flow transducers, and uterine and femoral artery catheters. Ovx animals (n= 8) were infused with vehicle (35% ethanol) or ICI 182 780 (0.1,3.0 ,g min,1) into one uterine artery for 10 min before and 50 min after E2, was given (1 ,g kg,1i.v. bolus) and UBF was recorded for an additional hour. Intact, cycling sheep were synchronized to the follicular phase using progesterone, prostaglandin F2,(PGF2,) and pregnant mare serum gonadotrophin (PMSG). When peri-ovulatory rises in UBF reached near peak levels, ICI 182 780 (1 or 2 ,g (ml uterine blood flow),1) was infused unilaterally (n= 4 sheep). Ewes in the last stages of pregnancy (late pregnant ewes) were also given ICI 182 780 (0.23,2.0 ,g (ml uterine blood flow),1; 60 min infusion) into one uterine artery (n= 8 sheep). In Ovx sheep, local infusion of ICI 182 780 did not alter systemic cardiovascular parameters, such as mean arterial blood pressure or heart rate; however, it maximally decreased ipsilateral, but not contralateral, UBF vasodilatory responses to exogenous E2, by ,55,60% (P < 0.01). In two models of elevated endogenous E2,, local ICI 182 780 infusion inhibited the elevated UBF seen in follicular phase and late pregnant ewes in a time-dependent manner by ,60% and 37%, respectively; ipsilateral , contralateral effects (P < 0.01). In late pregnant sheep ICI 182 780 also mildly and acutely (for 5,30 min) elevated mean arterial pressure and heart rate (P < 0.05). We conclude that exogenous E2,-induced increases in UBF in the Ovx animal and endogenous E2,-mediated elevations of UBF during the follicular phase and late pregnancy are partially mediated by ER-dependent mechanisms. [source] A unifying explanation for diverse metabolic scaling in animals and plantsBIOLOGICAL REVIEWS, Issue 1 2010Douglas S. Glazier The scaling of metabolic rate with body mass has long been a controversial topic. Some workers have claimed that the slope of log-log metabolic scaling relationships typically obeys a universal 3/4-power law resulting from the geometry of resource-transport networks. Others have attempted to explain the broad diversity of metabolic scaling relationships. Although several potentially useful models have been proposed, at present none successfully predicts the entire range of scaling relationships seen among both physiological states and taxonomic groups of animals and plants. Here I argue that our understanding may be aided by three shifts in focus: from explaining average tendencies to explaining variation between extreme boundary limits, from explaining the slope and elevation (metabolic level) of scaling relationships separately to showing how and why they are interrelated, and from focusing primarily on internal factors (e.g. body design) to a more balanced consideration of both internal and external (ecological) factors. By incorporating all of these shifts in focus, the recently proposed metabolic-level boundaries hypothesis appears to provide a useful way of explaining both taxonomic and physiological variation in metabolic scaling relationships. This hypothesis correctly predicts that the scaling slope should vary mostly between 2/3 and 1 and that it should be related to metabolic (activity) level according to an approximately U-shaped function. It also implies that the scaling of other energy-dependent biological processes should be related to the metabolic level of the organisms being examined. Some data are presented that support this implication, but further research is needed. [source] Young Children's Reasoning About the Effects of Emotional and Physiological States on Academic PerformanceCHILD DEVELOPMENT, Issue 1 2009Jennifer Amsterlaw This study assessed young children's understanding of the effects of emotional and physiological states on cognitive performance. Five, 6-, 7-year-olds, and adults (N= 96) predicted and explained how children experiencing a variety of physiological and emotional states would perform on academic tasks. Scenarios included: (a) negative and positive emotions, (b) negative and positive physiological states, and (c) control conditions. All age groups understood the impairing effects of negative emotions and physiological states. Only 7-year-olds, however, showed adult-like reasoning about the potential enhancing effects of positive internal states and routinely cited cognitive mechanisms to explain how internal states affect performance. These results shed light on theory-of-mind development and also have significance for children's everyday school success. [source] | |||||||||||||||||||