bluuebunny/crossref_metadata_2025 huggingface dataset:
THE FORMATION OF 2-PYRROLECARBOXYLIC ACID FROM HYDROXY-D- AND ALLOHYDROXY-D-PROLINE
Authors: Letellier G. , Bouthillier L. P.
Published: December 2009

Evidence is presented for the identity of chemically prepared 2-pyrrolecarboxylic acid and the metabolite formed in rat and human tissues from hydroxy-D-proline and allohydroxy-D-proline. 2-Pyrrolecarboxylic acid is not an intermediate in the biological degradation of natural hydroxyproline.
ACTIVATION OF SCHRADAN BY MAMMALIAN TISSUE HOMOGENATES
Authors: O'Brien R. D.
Published: December 2009

It has been confirmed that the combined microsomal and soluble fractions of liver, in the presence of magnesium, nicotinamide, and DPN, can convert schradan to a potent anticholinesterase. DPN can be replaced by TPN, but not by ATP. DPNH can replace the DPN and soluble fraction. Catalase enhances the conversion but only when DPNH or a source of it is provided. Acetone powders of microsomes, suitably fortified, are almost ineffective in converting schradan. The pH optimum of the whole schradan-converting system is 8.1. Other properties of the system are described. Certain extrahepatic tissues, especially lung, heart, and testis, can convert schradan. The livers of all species tested convert schradan. A peroxide-mediated mechanism of oxidation is proposed.
THE DISTRIBUTION OF ADMINISTERED VITAMIN K1-C14 IN RATS
Authors: Taylor J. D. , Millar G. J. , Jaques L. B. , Spinks J. W. T.
Published: December 2009

Radioactive vitamin K1-C14 was administered orally, intramuscularly, and intravenously to albino rats and the distribution of radioactive C14 determined. Isotope dilution studies were performed to ascertain the degree to which the vitamin K1-C14 was present in unchanged form in some tissues. Regardless of the route of administration, radioactivity was deposited in all the tissues. The liver accumulated the largest amounts of radioactivity but the spleen had a much higher specific activity following intravenous administration of the vitamin. Radioactivity could be detected in the liver for as long as 12 days after administration. When the log of the dose of vitamin K1-C14 (5.6–82 mgm./kgm.) was plotted against the log of the vitamin K1 equivalent in the various tissues a straight line relationship was obtained. The per cent of the injected dose present in the tissues 24 hr. after injection was as follows: liver 2.8, skeletal muscle 12.2, small intestine and contents 2.5, bile 26, feces 6.2, urine 0.98. The per cent of such activity present as unchanged vitamin K1-C14, as judged by isotope dilution tests, was liver 78, skeletal muscle 74, small intestine and contents 15, bile 1.5, feces 6.5, and urine 0.0.
ENZYMATIC PROPERTIES OF BOVINE PLASMIN PREPARATIONS; EVIDENCE FOR SIMILARITY TO BUT NON-IDENTITY WITH TRYPSIN
Authors: Ronwin Edward
Published: December 2009

The enzymatic properties of both choloroform-only activated and trypsin–chloroform activated bovine fibrinolysin (plasmin) have been studied and compared with trypsin. These studies accentuate the remarkable similarity between plasmin and trypsin but definitely establish their distinct individuality and the validity of the procedure using trypsin to activate plasminogen to plasmin.
INHIBITION OF AMINE OXIDASE BY METAL IONS AND BY SULPHYDRYL COMPOUNDS
Authors: Lagnado J. R. , Sourkes T. L.
Published: December 2009

Metal compounds were studied for possible effects on the amine oxidase system of rat liver. Some activated, others inhibited this system. Certain compounds exhibited both actions, the former being detectable at the lower concentrations. The data obtained extend the evidence of others for amine oxidase as a sulphydryl enzyme, but other mechanisms for metal inhibition of amine oxidase must also be considered. The actions of sulphydryl compounds on amine oxidase activity were investigated. BAL, thioglycollic acid, cysteine, and cystine were inhibitors, glutathione activated the enzyme system under certain conditions. Intravenous administration to rats of mercuric acetate, cadmium chloride, lead acetate, and manganese sulphate, all being in vitro inhibitors of amine oxidase, did not affect the enzyme activity of brain and liver in acute experiments.
CONVERSION OF PROTHROMBIN TO AUTOPROTHROMBIN II
Authors: Penner John A. , Duckert F. , Johnson Shirley A. , Seegers Walter H.
Published: December 2009

With thromboplastin, Ac-globulin, and calcium ions, purified prothrombin converts to biothrombin. This derivative of prothrombin is also obtained with purified platelet factor 3, Ac-globulin, calcium ions, and autoprothrombin II. Need for the latter substance by platelet factor 3 is one marked distinction that can be made between thromboplastin and platelet factor 3. Thromboplastin does not require a cofactor such as platelet cofactor I or autoprothrombin II. Ether extracts of dry brain or of purified platelet factor 3 or of whole platelets yield lipid material. The lipids obtained in this manner are active in a modified Biggs and Douglas thromboplastin generation test; but in contrast to the original thromboplastin or purified platelet factor 3 from which they are obtained do not activate purified prothrombin to thrombin. The lipid material is thus distinctly different from thromboplastin or from platelet factor 3. The lipid is also active in the conversion of prothrombin to autoprothrombin II when purified prothrombin is the substrate or when the prothrombin is in the original plasma or whole blood. Extraction of purified platelet factor 3 leaves a protein residue and it is believed that platelet factor 3 is a lipoprotein. The infrared absorption spectrum of the lipid obtained from purified platelet factor 3 shows strong absorption bands. From the general absorption pattern, we infer that the lipid is not a heterogeneous mixture, but most likely a single substance or consists of several that are nearly alike. Platelet factor 3 lipid(s) is most likely a cephalin-like compound.
STUDIES OF FATTY ACID OXIDATION: 4. THE EFFECTS OF FATTY ACIDS ON THE OXIDATION OF OTHER METABOLITES
Authors: Scholefield P. G.
Published: December 2009

Fatty acids inhibit the oxidation of pyruvate by rat-kidney mitochondria but the extent of inhibition depends upon the nature and amount of agent added to stimulate the oxidation. The longer chain fatty acids are more effective inhibitors and, in general, the even-numbered fatty acids show greater inhibitory effects than the adjacent odd-numbered fatty acids. Under conditions where 2, 4-dinitrophenol (DNOP) and the fatty acids separately have little effect on the respiratory activity of rat-kidney mitochondria with pyruvate as substrate, the addition of both fatty acid and DNOP results in an extensive inhibition. At low concentrations the fatty acids are oxidized by rat-kidney mitochondria but at concentrations of 10−3 M and higher they inhibit their own oxidation, the oxidation of pyruvate, and those of the acids of the tricarboxylic acid cycle. The oxidation of pyruvate by rat-brain mitochondria is insensitive to decanoate but both the fumarate- and DNOP-stimulated oxidations of pyruvate are sensitive to the presence of decanoate. In contrast, Nembutal inhibits both the oxidation of pyruvate alone and the fumarate-stimulated oxidation of pyruvate. Possible mechanisms for the observed inhibitory effects of fatty acids are discussed.
STUDIES OF FATTY ACID OXIDATION: 5. THE EFFECT OF DECANOIC ACID ON OXIDATIVE PHOSPHORYLATION
Authors: Scholefield P. G.
Published: December 2009

The effects of potassium decanoate on the phosphorylation associated with the oxidation of pyruvate by rat-kidney and rat-brain mitochondria have been investigated. The suggestion that these two processes may be uncoupled from each other in the presence of decanoate has been confirmed. Further, it has been shown that the decanoate-insensitive oxidation of pyruvate by rat-brain mitochondria, occurring in the absence of such stimulating agents as fumarate, is not associated with ATP synthesis. The fumarate-stimulated oxidation of pyruvate by rat-brain mitochondria, which is inhibited by decanoate, is associated with a phosphorylation process which is uncoupled by decanoate. When pyruvate oxidation by rat-kidney or by rat-brain mitochondria is uncoupled from phosphorylation, the extent of uncoupling is proportional to the amount of decanoate added.
ETHYLENE METABOLISM IN TOMATO FRUIT: I. RELATIONSHIP OF ETHYLENE EVOLUTION TO FRUIT RESPIRATION AND RIPENING
Authors: Spencer Mary S.
Published: December 2009

Ripening tomatoes were found to possess a climacteric peak in carbon dioxide production which was accompanied by evolution of ethylene. When the fruit was placed in oxygen, ripening and evolution of ethylene were accelerated in proportion to the increase in respiration. Peaks in carbon dioxide and ethylene evolution occurred not only when the fruit ripened, but also afterwards, during senescence. On the other hand, young, green fruit possessed a pronounced peak in carbon dioxide evolution without changes in color or texture or evolution of significant amounts of ethylene. Thus a series of waves in carbon dioxide production occurred as the tomato developed, ripened, and aged. Waves in ethylene evolution accompanied the carbon dioxide once the ripening process began. Evolution of large amounts of ethylene appeared to be associated with changes in the metabolic pathway that occurred with ripening, rather than being an accompaniment for increased respiration at any stage in the development of the fruit.
COMPUTATIONAL MODELING OF RIVER DELTA FORMATION
Authors: HERRMANN HANS J. , SEYBOLD HANSJÖRG
Published: December 2009

A new model to simulate the time evolution of river delta formation process is presented in Ref. 46. It is based on the continuity equation for water and sediment flow and a phenomenological sedimentation/erosion law. Different delta types are reproduced using different parameters and erosion rules. The model is capable to describe the subaerial and subaqueous growth of the delta front and the fromation of levees. The structures of the calculated patterns are analyzed in space and time and compared with real data patterns. Furthermore our model is capable to simulate the rich dynamics related to the switching of the mouth of the river delta. The simulation results are then compared with geological records for the Mississippi river.
GRANULAR FAILURE: THE ORIGIN OF EARTHQUAKES?
Authors: CIAMARRA MASSIMO PICA , DE ARCANGELIS LUCILLA , LIPPIELLO EUGENIO , GODANO CATALDO
Published: December 2009

Via Molecular Dynamics simulations, we investigate the stick-slip motion in a model of fault, where two surfaces subject to a constant confining pressure P, and enclosing granular particles, are subject a shear stress σ. When the system sticks, the stress increases with a constant rate [Formula: see text], while the stress decreases when the system flow. We dermine the system 'phase diagram' in the pressure P load velocity [Formula: see text] plane, locating the transition form the continuos flow regime to the stick-slip regimes, and show that the transition between these two regimes is characterized by the presence of large fluctuations. In the stick-slip regime, the system reproduces the behaviour of a segment of a fault of fixed lenght.
INFLUENCE OF LOCAL DUST SOURCE AND STOCHASTIC FLUCTUATIONS ON SAHARAN AEROSOL INDEX DYNAMICS
Authors: CUOMO V. , DE MARTINO S. , FALANGA M. , MONA L.
Published: December 2009

We analyse time series of the Aerosol Index, a parameter related to the aerosol content and retrieved by satellite observations. In particular, we consider data recorded on oriental part of Sahara. A stochastic equation describes the behaviour of the Aerosol Index as occurs in Italy, but out of a stochastic resonance regime. We prove that, in the oriental part of Sahara, local dust source is simply linear superimposed to noise so that a stochastic resonance regime is not set. Furthermore, we find that the local dust emission strongly influences the Aerosol Index data and it is responsible for about 78% of the annual periodicity in the signal.
APPLICATION OF PERCOLATION THEORY AND RG METHOD TO SOIL MOISTURE DYNAMICS
Authors: DI DOMENICO ANTONELLA , LAGUARDIA GIOVANNI
Published: December 2009

In this work, we present a review of the results obtained in the exploitation of percolation theory and the renormalization group method in the study of soil moisture spatial patterns.

In order to capture critical point in soil moisture spatio-temporal dynamics, we developed an algorithm consisting of three steps: (i) dichotomization, i.e., transforming the soil moisture maps into binary maps; (ii) identification of the largest wet cluster; (iii) scaling transformation, i.e., applying an ad hoc implemented coarse-graining procedure to the binary maps.

The methodology was explored by means of several applications on soil moisture data coming from field measurement, remote sensing, and hydrological modelling over a wide range of spatial scales. From the relations between the occupation probability in soil moisture spatial patterns and the normalized size of the largest cluster at different scales, as well as the scaling behaviour, it is possible to argue that also for this physical system the critical point theory applies.

The critical probability seems to be a structural feature of the catchment, being insensitive to the scale of the analysis, as well as to the parameterization of the methodology.
CONTINUUM CLIMATE VARIABILITY: LONG-TERM MEMORY, SCALING, AND 1/F-NOISE
Authors: FRAEDRICH KLAUS , BLENDER RICHARD , ZHU XIUHUA
Published: December 2009

Continuum temperature variability represents the response of the Earth's climate to deterministic external forcing. Scaling regimes are observed which range from hours to millennia with low frequency fluctuations characterizing long-term memory. The presence of 1/f power spectra in weather and climate is noteworthy: (i) In the tropical atmosphere 1/f scaling ranging from hours to weeks is found for several variables; it emerges as superposition of uncorrelated pulses with individual 1/f spectra. (ii) The daily discharge of the Yangtze shows 1/f within one week to one year, although the precipitation spectrum is white. (iii) Beyond one year mid-latitude sea surface temperatures reveal 1/f scaling in large parts of the global ocean. The spectra can be simulated by complex atmosphere-ocean general circulation models and understood as a two layer heat diffusion process forced by an uncorrelated stochastic atmospheric. Long-term memory on time scales up to millennia are the global sea surface temperatures and the Greenland ice core records (GISP2, GRIP) with δ18 O temperature proxy data during the Holocene. Complex atmosphere ocean general circulation models reproduce this behavior quantitatively up to millennia without solar variability, interacting land-ice and vegetation components.
STOCHASTIC MODELING AND FILTERING OF DISCRETE MEASUREMENTS FOR A TURBULENT FIELD: APPLICATION TO MEASUREMENTS OF ATMOSPHERIC WIND
Authors: BAEHR C.
Published: December 2009

Non-linear filtering of local turbulent fluid measurements was an unexplored domain, in this paper we present original stochastic models and efficient filters to perform it. First we propose non-linear filters for processes of a mean-field law and give the convergence of their particle approximations. Then we define the acquisition process of a vector field along a random path. We deeply modify the Lagrangian models of fluids proposed by the physicists to make them compatible with the problem of filtering, the closure of these equations is obtained by conditioning the dynamics to the observations and to the acquisition process. Our algorithm allowed us to filter velocity measurements of a real turbulent fluid in 3D flows.
DROPLET FEEDBACK ON VAPOR IN A WARM CLOUD
Authors: CELANI ANTONIO , MAZZINO ANDREA , TIZZI MARCO
Published: December 2009

A new model to study the effect of turbulence on the cloud droplets in the condensation phase is proposed and its behavior investigated by direct numerical simulations. The model is a generalization of the one by Celani, Mazzino, Tizzi, New J. Phys.10, 075021 (2008), where the droplet feedback on vapor is now explicitly taken into account. Physically, it amounts to considering the fact that when a cloud droplet increases its size, vapor is subtracted from the ambient with the net result of a local reduction in the supersaturation field. It is shown how this effect plays to reduce the broadening of droplet size spectra in the condensation stage and thus to produce results in closer agreement with observations.
ATMOSPHERIC CONVECTION AS A CONTINUOUS PHASE TRANSITION: FURTHER EVIDENCE
Authors: PETERS OLE , NEELIN J. DAVID
Published: December 2009

We present further methods to investigate in how far atmospheric precipitation can be described as a continuous phase transition. Previous work has shown a scale-free range in the rainfall event size distribution and a suggestive power-law pickup in the rain rate above a critical level of instability. Here we examine an additional technique for estimating critical parameters, we investigate the rain rate pickup for an example of an extreme event, namely satellite observations of Hurricane Katrina, and develop an analysis of fluctuations in the rain rate to estimate uncertainties in the tuning parameters relevant for the transition.
THE DYNAMO BIFURCATION IN ROTATING SPHERICAL SHELLS
Authors: MORIN VINCENT , DORMY EMMANUEL
Published: December 2009

We investigate the nature of the dynamo bifurcation in a configuration applicable to the Earth's liquid outer core, i.e. in a rotating spherical shell with thermally driven motions. We show that the nature of the bifurcation, which can be either supercritical or subcritical or even take the form of isola (or detached lobes) strongly depends on the parameters. This dependence is described in a range of parameters numerically accessible (which unfortunately remains remote from geophysical application), and we show how the magnetic Prandtl number and the Ekman number control these transitions.
STATISTICAL ANALYSIS OF MAGNETIC FIELD REVERSALS IN LABORATORY DYNAMO AND IN PALEOMAGNETIC MEASUREMENTS
Authors: SORRISO-VALVO LUCA , CARBONE VINCENZO , BOURGOIN MICHAEL , ODIER PHILIPPE , PLIHON NICOLAS , VOLK ROMAIN
Published: December 2009

Statistical properties of the temporal distribution of polarity reversals of the geomagnetic field are commonly assumed to be a realization of a renewal Poisson process with a variable rate. However, it has been recently shown that the polarity reversals strongly depart from a local Poisson statistics, because of temporal clustering. Such clustering arises from the presence of long-range correlations in the underlying dynamo process. Recently achieved laboratory dynamo also shows reversals. It is shown here that laboratory and paleomagnetic data are both characterized by the presence of long-range correlations.
MAGNETIC FIELD REVERSALS OF THE EARTH: A TWO–DISK RIKITAKE DYNAMO MODEL
Authors: DONATO SANDRO , MEDURI DOMENICO , LEPRETI FABIO
Published: December 2009

The Sun and the Earth possess dipolar magnetic fields that exhibit polarity reversals. Recent works, based on numerical simulations and laboratory experiments, found similar dynamical behaviours. We present results of a statistical analysis of a numerical simulation based on a generalized two–disk dynamo model. From a first investigation, we found that the dynamics of the system is controlled by the variations of the ratio of the torques and we observed different dynamical regimes characterized either by bursts or reversals, which can be periodic or random, of the magnetic field.
COUPLED SELF-OSCILLATING SYSTEMS: THEORY AND APPLICATIONS
Authors: GUERRA FRANCESCO
Published: December 2009

We review the structure of self-oscillating dynamical systems, and point out the numerous applications that they can have. In the case of coupled self-oscillating systems, the typical features of complexity show up, in a completely dynamical setting. This general scheme goes well beyond Fourier analysis, and allows to consider modes at the various time scale levels in a frame where non-linearity plays an essential role. We discuss some basic applications to speech generation, hydrodynamic instabilities, volcanic tremor. Possible lines of development are pointed out.
STATISTICAL TESTS FOR SCALING IN THE INTER-EVENT TIMES OF EARTHQUAKES IN CALIFORNIA
Authors: CORRAL ÁLVARO
Published: December 2009

We explore in depth the validity of a recently proposed scaling law for earthquake inter-event time distributions in the case of the Southern California, using the waveform cross-correlation catalog of Shearer et al. Two statistical tests are used: on the one hand, the standard two-sample Kolmogorov-Smirnov test is in agreement with the scaling of the distributions. On the other hand, the one-sample Kolmogorov-Smirnov statistic complemented with Monte Carlo simulation of the inter-event times, as done by Clauset et al., supports the validity of the gamma distribution as a simple model of the scaling function appearing on the scaling law, for rescaled inter-event times above 0.01, except for the largest data set (magnitude greater than 2). A discussion of these results is provided.
TIME, SPACE AND MAGNITUDE CORRELATIONS IN EARTHQUAKE OCCURRENCE
Authors: LIPPIELLO E. , DE ARCANGELIS L. , GODANO C.
Published: December 2009

Clustering in time and space is a widely accepted feature of seismicity. Much more questionable is the existence of magnitude correlations. The standard approach to time-dependent seismic hazard generally assumes that magnitudes are independent and therefore, in principle, the next earthquake magnitude is unpredictable. We will show that an earthquake magnitude depends on previous ones: earthquakes occur with higher probability close, not only in time and space, but also in magnitude to previous events. Moreover, the magnitude difference fixes the characteristic temporal and spatial scale controlling correlations between events. As a consequence, the next earthquake tends to have a magnitude similar but smaller than the previous one. We will discuss a dynamical scaling relation between energy, time and space distance that reproduces the main statistical properties of experimental catalogs.
STATISTICAL PROPERTIES OF SOLAR FLARES AND COMPARISON TO OTHER IMPULSIVE ENERGY RELEASE EVENTS
Authors: LEPRETI FABIO , KOSSOBOKOV VLADIMIR G. , CARBONE VINCENZO
Published: December 2009

Impulsive energy release events are observed in many natural systems. Solar flares are certainly among the most remarkable examples of such processes. In the last years the study of solar flare statistical properties has received considerable attention in the context of solar flare models based on different approaches, such as Self Organized Criticality (SOC) or magnetohydrodynamic (MHD) turbulence. In this talk the main statistical properties of solar flares will be presented and compared to those of other well known impulsive processes, such as earthquakes and soft γ-ray flashes occurring on neutron stars. It is shown that the these phenomena are characterized by different statistics that cannot be rescaled onto a single, universal curve and that this holds even for the same phenomenon, when observed in different periods or at different locations. Our results indicate apparent complexity of impulsive energy release processes, which neither follow a common behavior nor could be attributed to a universal physical mechanism.
The Psychology of Academic Achievement
Authors: Winne Philip H. , Nesbit John C.
Published: December 2009

Educational psychology has generated a prolific array of findings about factors that influence and correlate with academic achievement. We review select findings from this voluminous literature and identify two domains of psychology: heuristics that describe generic relations between instructional designs and learning, which we call the psychology of “the way things are,” and findings about metacognition and self-regulated learning that demonstrate learners selectively apply and change their use of those heuristics, which we call the psychology of “the way learners make things.” Distinguishing these domains highlights a need to marry two approaches to research methodology: the classical approach, which we describe as snapshot, bookend, between-group experimentation; and a microgenetic approach that traces proximal cause-effect bonds over time to validate theoretical accounts of how learning generates achievements. We argue for fusing these methods to advance a validated psychology of academic achievement.
Structural Plasticity and Hippocampal Function
Authors: Leuner Benedetta , Gould Elizabeth
Published: December 2009

The hippocampus is a region of the mammalian brain that shows an impressive capacity for structural reorganization. Preexisting neural circuits undergo modifications in dendritic complexity and synapse number, and entirely novel neural connections are formed through the process of neurogenesis. These types of structural change were once thought to be restricted to development. However, it is now generally accepted that the hippocampus remains structurally plastic throughout life. This article reviews structural plasticity in the hippocampus over the lifespan, including how it is investigated experimentally. The modulation of structural plasticity by various experiential factors as well as the possible role it may have in hippocampal functions such as learning and memory, anxiety, and stress regulation are also considered. Although significant progress has been made in many of these areas, we highlight some of the outstanding issues that remain.
Child Maltreatment and Memory
Authors: Goodman Gail S. , Quas Jodi A. , Ogle Christin M.
Published: December 2009

Exposure to childhood trauma, especially child maltreatment, has important implications for memory of emotionally distressing experiences. These implications stem from cognitive, socio-emotional, mental health, and neurobiological consequences of maltreatment and can be at least partially explained by current theories concerning the effects of childhood trauma. In this review, two main hypotheses are advanced: (a) Maltreatment in childhood is associated with especially robust memory for emotionally distressing material in many individuals, but (b) maltreatment can impair memory for such material in individuals who defensively avoid it. Support for these hypotheses comes from research on child abuse victims' memory and suggestibility regarding distressing but nonabusive events, memory for child abuse itself, and autobiographical memory. However, more direct investigations are needed to test precisely when and how childhood trauma affects memory for emotionally significant, distressing experiences. Legal implications and future directions are discussed.
A Bridge Over Troubled Water: Reconsolidation as a Link Between Cognitive and Neuroscientific Memory Research Traditions
Authors: Hardt Oliver , Einarsson Einar Örn , Nader Karim
Published: December 2009

There are two research traditions on dynamic memory processes. In cognitive psychology, the malleable nature of long-term memory has been extensively documented. Distortions, such as the misinformation effect or hindsight bias, illustrate that memories can be easily changed, often without their owner taking notice. On the other hand, effects like hypermnesia demonstrate that memory might be more reliable than these distortions suggest. In the neuroscience field, similar observations were obtained mostly from animal studies. Research on memory consolidation suggested that memories become progressively resistant to amnesic treatments over time, but the reconsolidation phenomenon showed that this stability can be transiently lifted when these memories are reactivated, i.e., retrieved. Surprisingly, both research traditions have not taken much notice of each others' advances in understanding memory dynamics. We apply concepts developed in neuroscience to phenomena revealed in cognitive psychology to illustrate how these twins separated at birth may be reunited again.
Patterns of Gender Development
Authors: Martin Carol Lynn , Ruble Diane N.
Published: December 2009

A comprehensive theory of gender development must describe and explain long-term developmental patterning and changes and how gender is experienced in the short term. This review considers multiple views on gender patterning, illustrated with contemporary research. First, because developmental research involves understanding normative patterns of change with age, several theoretically important topics illustrate gender development: how children come to recognize gender distinctions and understand stereotypes, and the emergence of prejudice and sexism. Second, developmental researchers study the stability of individual differences over time, which elucidates developmental processes. We review stability in two domains—sex segregation and activities/interests. Finally, a new approach advances understanding of developmental patterns, based on dynamic systems theory. Dynamic systems theory is a metatheoretical framework for studying stability and change, which developed from the study of complex and nonlinear systems in physics and mathematics. Some major features and examples show how dynamic approaches have been and could be applied in studying gender development.
MEASUREMENT OF SERUM LEPTIN CONCENTRATIONS IN UNIVERSITY UNDERGRADUATES BY COMPETITIVE ELISA REVEALS CORRELATIONS WITH BODY MASS INDEX AND SEX
Authors: Chow Vincent T. K. , Phoon M. C.
Published: December 2009

Synthesized mainly in adipocytes, leptin is a peptide hormone that plays a key role in the regulation of body weight and composition. The serum leptin concentrations of 193 Singapore university medical and bioscience undergraduates aged 19–26 yr were measured using a competitive ELISA kit, and their leptin levels were correlated with sex and body mass index (BMI). Mean leptin levels were more than twice as high in females than in males of corresponding weight status, especially among females of healthy weight who exhibited levels that were 5.7 times higher. Overweight individuals generally demonstrated higher circulating leptin concentrations than healthy-weight and underweight participants. The differences in mean leptin levels between underweight and overweight males ( P = 0.006), as well as between healthy-weight and overweight males ( P = 0.011) were statistically significant. Comparison tests of leptin levels between healthy-weight and underweight females were highly significant ( P = 0.001). Highly significant linear correlations between BMI and the logarithm of leptin concentration were observed in the female ( r = 0.44) and male ( r = 0.36) groups. These results reiterate the impact of gonadal steroids as mediators of the apparent sexual dimorphism in circulating leptin. The findings also corroborate evidence that adiposity determines leptin levels. This laboratory exercise has educational value for undergraduates by determining their BMIs, by alluding to the importance of maintaining healthy body composition, and by emphasizing the molecular mechanisms of body weight regulation and obesity, with special reference to leptin. This practical study also exemplifies the principles and applications of the competitive ELISA technique and integrates certain key concepts of physiology, molecular biology, immunology, and medicine.
THE EFFECT OF ACTIVE LEARNING ON STUDENT CHARACTERISTICS IN A HUMAN PHYSIOLOGY COURSE FOR NONMAJORS
Authors: Wilke R. Russell
Published: December 2009

This study investigated the effect of active-learning strategies on college students’ achievement, motivation, and self-efficacy in a human physiology course for nonmajors. Variables were studied via a quasi-experimental, Solomon four-group design on 141 students at a small west-Texas university. Treatment groups were taught using a continuum-based, active-learning model implemented over the course of a semester. Control groups were taught using traditional didactic lecture methods. To assess the effects of the continuum-based active learning strategies, students were administered a comprehensive physiology content exam, the Motivated Strategies for Learning Questionnaire, and attitude surveys. Factorial analyses indicated that the treatment groups acquired significantly more content knowledge and were significantly more self-efficacious than students in the control groups. There were no significant differences in motivation. Attitude surveys indicated that students in both the treatment and control groups demonstrated a positive attitude toward active learning, believed it helped (or would help) them to learn the material, and would choose an active learning course in the future.
RESTORING PHYSIOLOGY TO THE UNDERGRADUATE BIOLOGY CURRICULUM: A CALL FOR ACTION
Authors: Silverthorn Dee U.
Published: December 2009

The National Research Council-sponsored report, BIO 2010: Transforming Undergraduate Education for Future Research Biologists, describes a number of significant changes that should be made to the undergraduate biology curriculum if we are to adequately train students to become the researchers of the 21st century. What should be of concern to the physiology community is the lack of identifiable physiology in the proposed revisions. This article describes the report and suggests some steps that physiologists can take to enhance our discipline in the undergraduate biology curriculum.
LAPLACE’S LAW AND THE ALVEOLUS: A MISCONCEPTION OF ANATOMY AND A MISAPPLICATION OF PHYSICS
Authors: Prange Henry D.
Published: December 2009

Both the anatomy and the mechanics of inflation of the alveoli, as presented in most textbooks of physiology, have been misunderstood and misrepresented. The typical representation of the acinus as a “bunch of grapes” bears no resemblance to its real anatomy; the alveoli are not independent little balloons. Because of the prevalence of this misconception, Laplace’s law, as it applies to spheres, has been invoked as a mechanical model for the forces of alveolar inflation and as an explanation for the necessity of pulmonary surfactant in the alveolus. Alveoli are prismatic or polygonal in shape, i.e., their walls are flat, and Laplace law considerations in their inflation apply only to the very small curved region in the fluid where these walls intersect. Alveoli do not readily collapse into one another because they are suspended in a matrix of connective tissue “cables” and share common, often perforated walls, so there can be no pressure differential across them. Surfactant has important functions along planar surfaces of the alveolar wall and in mitigating the forces that tend to close the small airways. Laplace’s law as it applies to cylinders is an important feature of the mechanics of airway collapse, but the law as it applies to spheres is not relevant to the individual alveolus.
A SIMPLE BALLISTOCARDIOGRAPHIC SYSTEM FOR A MEDICAL CARDIOVASCULAR PHYSIOLOGY COURSE
Authors: Eblen-Zajjur Antonio
Published: December 2009

Ballistocardiography is an old, noninvasive technique used to record the movements of the body synchronous with the heartbeat due to left ventricular pump activity. Despite the fact that this technique to measure cardiac output has been superseded by more advanced and precise techniques, it is useful for teaching cardiac cycle physiology in an undergraduate practical course because of its noninvasive application in humans, clear physiological and physiopathological analysis, and practical approach to considering cardiac output issues. In the present report, a simple, low cost, easy-to-build ballistocardiography system is implemented together with a theoretical and practical session that includes Newton’s laws, cardiac output, cardiac pump activity, anatomy and physiology of the vessel circulation, vectorial composition, and signal transduction, which makes cardiovascular physiology easy to understand and focuses on the study of cardiac output otherwise seen only with the help of computer simulation or echocardiography. The proposed system is able to record body displacement or force as ballistocardiography traces and its changes caused by different physiological factors. The ballistocardiography session was included in our medical physiology course six years ago with very high acceptance and approval rates from the students.
USING MANIPULATIVES TO IMPROVE LEARNING IN THE UNDERGRADUATE NEUROPHYSIOLOGY CURRICULUM
Authors: Krontiris-Litowitz Johanna
Published: December 2009

Educational research has demonstrated that the use of concrete objects or manipulatives in the classroom enhances problem-solving skills and conceptual learning. This project examines the use of manipulatives in a neurophysiology curriculum and assesses their effectiveness on student comprehension. Three activities, building an ion channel, building a nerve cell, and passive membrane properties, were developed using modeling clay and beads as manipulatives. Their effect on learning was assessed in a neurobiology class that had been divided into an experimental group that worked with manipulative-based activities and a control group that did not. After the experimental group had completed the manipulative activity, both groups were given a quiz. Students who had used manipulatives scored significantly better than those who had not. In a second study, students were given a quiz before and after completing a manipulative activity. Students who had used manipulatives showed the greatest grade improvement. These studies suggest that manipulative activities can be used to enhance learning in the neurophysiology curriculum.
AN INNOVATIVE METHOD TO ENHANCE INTERACTION DURING LECTURE SESSIONS
Authors: Kumar Sanjay
Published: December 2009

The B. P. Koirala Institute of Health Sciences, Dharan, is following an innovative hybrid curriculum. Conventional lectures are replaced by “structured interactive sessions” (SIS). SIS involves increased interchange between teachers, students, and lecture contents by proper planning and organized efforts. It can promote active learning and heighten attention and motivation. The present study was conducted to enhance active interactions during such sessions. The students were divided into two groups and asked to come prepared for the lectures. Students were encouraged to ask questions and interact informally during lectures. A scoreboard was maintained, and student feedback was taken at the end of the lecture block. The entire student response was reduced to a student acceptability index (SAI). Our results show a statistically significant increase in interactions per student per day. A majority of the responses in the questionnaire and SAI were favorable. Specific comments and suggestions of students were also positive. These results show that simple innovative techniques enhance the interactions during a lecture session.
SIMULATED HUMAN DIVING AND HEART RATE: MAKING THE MOST OF THE DIVING RESPONSE AS A LABORATORY EXERCISE
Authors: Hiebert Sara M. , Burch Elliot
Published: December 2009

Laboratory exercises in which students examine the human diving response are widely used in high school and college biology courses despite the experience of some instructors that the response is unreliably produced in the classroom. Our experience with this exercise demonstrates that the bradycardia associated with the diving response is a robust effect that can easily be measured by students without any sophisticated measurement technology. We discuss measures that maximize the success of the exercise by reducing individual variation, designing experiments that are minimally affected by change in the response over time, collecting data in appropriate time increments, and applying the most powerful statistical analysis. Emphasis is placed on pedagogical opportunities for using this exercise to teach general principles of physiology, experimental design, and data analysis. Data collected by students, background information for instructors, a discussion of the relevance of the diving reflex to humans, suggestions for additional experiments, and thought questions with sample answers are included.
HYPERTENSION MODULE: AN INTERACTIVE LEARNING TOOL IN PHYSIOLOGY
Authors: İşman Ç. A. , Gülpinar M. A. , Kurtel H. , Alican İ. , Yeğen B. Ç.
Published: December 2009

The aim of the present study was to evaluate the strong or weak aspects of an interactive study module introduced during the “Cardiovascular and Respiratory Systems Subject Committee” in the second year of the medical program. Five study groups consisting of 25 students attended two-hour module sessions for six weeks with the same tutor. According to the module assessment questionnaire, the majority of the students assessed the module as excellent or good. The students reported that they had gained not only in knowledge but also in skills development. The general opinion of the students was that both the organization and the implementation of the module met their expectations. Nearly one-half of the students reported that their expectations with regard to the educational environment and the participation of students were fully met. The major weakness in this new educational trial appears to be assessment of the module.
Toward consistent definitions for preload and afterload—revisited
Authors: ROTHE CARL
Published: December 2009

The following is the abstract of the article discussed in the subsequent letter:

Norton JM. Toward consistent definitions for preload and afterload. Advan Physiol Educ 25: 53–61, 2001. Significant differences exist among textbook definitions for the terms preload and afterload, leading to confusion and frustration among students and faculty alike. Many faculty also chose to use in their teaching simple terms such as “end-diastolic volume” or “aortic pressure” as common-usage approximations of preload and afterload, respectively, but these are only partial representations of these important concepts. Straightforward definitions both of preload and afterload that are concise yet still comprehensive can be developed using the Law of LaPlace to describe the relationships among chamber pressure, chamber radius, and wall thickness. Within this context, the term “preload” can be defined as all of the factors that contribute to passive ventricular wall stress (or tension) at the end of diastole, and the term “afterload” can be defined as all of the factors that contribute to total myocardial wall stress (or tension) during systolic ejection. The inclusion of “wall stress” in both definitions helps the student appreciate both the complexities of cardiac pathophysiology and the rationale for therapeutic intervention.
The mechanisms underlying the generation of the colonic migrating motor complex in both wild-type and nNOS knockout mice
Authors: Dickson Eamonn J. , Heredia Dante J. , McCann Conor J. , Hennig Grant W. , Smith Terence K.
Published: December 2009

Colonic migrating motor complexes (CMMCs) propel fecal contents and are altered in diseased states, including slow-transit constipation. However, the mechanisms underlying the CMMCs are controversial because it has been proposed that disinhibition (turning off of inhibitory neurotransmission) or excitatory nerve activity generate the CMMC. Therefore, our aims were to reexamine the mechanisms underlying the CMMC in the colon of wild-type and neuronal nitric oxide synthase (nNOS)−/− mice. CMMCs were recorded from the isolated murine large bowel using intracellular recordings of electrical activity from circular muscle (CM) combined with tension recording. Spontaneous CMMCs occurred in both wild-type (frequency: 0.3 cycles/min) and nNOS−/− mice (frequency: 0.4 cycles/min). CMMCs consisted of a hyperpolarization, followed by fast oscillations (slow waves) with action potentials superimposed on a slow depolarization (wild-type: 14.0 ± 0.6 mV; nNOS−/−: 11.2 ± 1.5 mV). Both atropine (1 μM) and MEN 10,376 [neurokinin 2 (NK2) antagonist; 0.5 μM] added successively reduced the slow depolarization and the number of action potentials but did not abolish the fast oscillations. The further addition of RP 67580 (NK1 antagonist; 0.5 μM) blocked the fast oscillations and the CMMC. Importantly, none of the antagonists affected the resting membrane potential, suggesting that ongoing tonic inhibition of the CM was maintained. Fecal pellet propulsion, which was blocked by the NK2 or the NK1 antagonist, was slower down the longer, more constricted nNOS−/− mouse colon (wild-type: 47.9 ± 2.4 mm; nNOS−/−: 57.8 ± 1.4 mm). These observations suggest that excitatory neurotransmission enhances pacemaker activity during the CMMC. Therefore, the CMMC is likely generated by a synergistic interaction between neural and interstitial cells of Cajal networks.
Signaling in TRPV1-induced platelet activating factor (PAF) in human esophageal epithelial cells
Authors: Ma Jie , Harnett Karen M. , Behar Jose , Biancani Piero , Cao Weibiao
Published: December 2009

Transient receptor potential channel, vanilloid subfamily member 1 (TRPV1) receptors were identified in human esophageal squamous epithelial cell line HET-1A by RT-PCR and by Western blot. In fura-2 AM-loaded cells, the TRPV1 agonist capsaicin caused a fourfold cytosolic calcium increase, supporting a role of TRPV1 as a capsaicin-activated cation channel. Capsaicin increased production of platelet activating factor (PAF), an important inflammatory mediator that acts as a chemoattractant and activator of immune cells. The increase was reduced by the p38 MAP kinase (p38) inhibitor SB203580, by the cytosolic phospholipase A2 (cPLA2) inhibitor AACOCF3, and by the lyso-PAF acetyltransferase inhibitor sanguinarin, indicating that capsaicin-induced PAF production may be mediated by activation of cPLA2, p38, and lyso-PAF acetyltransferase. To establish a sequential signaling pathway, we examined the phosphorylation of p38 and cPLA2by Western blot. Capsaicin induced phosphorylation of p38 and cPLA2. Capsaicin-induced p38 phosphorylation was not affected by AACOCF3. Conversely, capsaicin-induced cPLA2phosphorylation was blocked by SB203580, indicating that capsaicin-induced PAF production depends on sequential activation of p38 and cPLA2. To investigate how p38 phosphorylation may result from TRPV1-mediated calcium influx, we examined a possible role of calmodulin kinase (CaM-K). p38 phosphorylation was stimulated by the calcium ionophore A23187 and by capsaicin, and the response to both agonists was reduced by a CaM inhibitor and by CaM-KII inhibitors, indicating that calcium induced activation of CaM and CaM-KII results in P38 phosphorylation. Acetyl-CoA transferase activity increased in response to capsaicin and was inhibited by SB203580, indicating that p38 phosphorylation in turn causes activation of acetyl-CoA transferase to produce PAF. Thus epithelial cells produce PAF in response to TRPV1-mediated calcium elevation.