bluuebunny/crossref_metadata_2025 huggingface dataset:
Carbon dioxide exchange and phytochrome control of flowering in Xanthium pennsylvanicum
Authors: Bassi P. K. , Tregunna E. B. , Jolliffe P. A.
Published: September 2008

The presence of CO2 at sufficiently high concentrations is necessary for red light night interruptions to affect flowering in Xanthium pennsylvanicum L. The present study investigated the involvement of CO2 exchange in the effects of night interruptions on flowering. Brief red or far-red treatments were applied to Xanthium plants under inductive night conditions, and flowering response was assessed according to bud morphology 10 days after light treatment. The occurrence of flowering depended on the timing, wavelength, and intensity of the light treatments and on the CO2 concentration during the treatments. During the night interruptions CO2 exchange was measured in single attached leaves. CO2 exchange was influenced by the conditions during the night interruptions, but there was no apparent relationship between the patterns of CO2 exchange observed and the subsequent flowering responses to the night interruptions. Brief (10–60 s) high-intensity red light interruptions at 350 ppm CO2 had much less effect on CO2 exchange than did 5 min of low-intensity red light interruptions given at 20 ppm CO2. The brief light interruptions inhibited flowering, while the longer interruptions at low CO2 concentrations were ineffective. Moreover, far-red reversal of red light effects was not accompanied by alterations in CO2 exchange. It appears that the action of CO2 in night interruptions is not associated with CO2 exchange during the interruptions.
The effect of common root rot on components of grain yield in Manitou wheat
Authors: Verma P. R. , Morrall R. A. A. , Tinline R. D.
Published: September 2008

The effects of common root rot (Cochliobolus sativus) on components of grain yield in naturally infected Triticum aestivum cultivar Manitou were studied at Matador, Saskatchewan, by sampling plants at maturity in 1969, 1970, and 1971. Plants were sorted into severe (SE), moderate (MO), slight (SL), and clean (CL) categories based mainly on the extent of lesions on the subcrown internodes. The number of tillers per plant, the number and weight of grains per head, the weight per head, and the 1000-kernel weight in each category were determined. Increasing values of all five components were consistently associated with decreasing disease severity. SE was mostly significantly different from the other three categories in all components except 1000-kernel weight; differences between SL and MO were usually non-significant. CL and SL were mostly significantly different for the number of tillers per plant and weight per head but non-significant for the weight and number of grains per head and 1000-kernel weight. Apparently, the major effect of common root rot was to reduce the number of tillers per plant and number of grains per head.
Écoulement saturé et non saturé de l’eau souterraine vers des drains en aquifère à nappe libre
Authors: Chapuis Robert P. , Dénes Adrienne
Published: September 2008

The drainage of sports fields, highways, farm lands, and covers for wastes corresponds to the drainage of a shallow unconfined aquifer resting on a horizontal or sloping impervious substratum. The seepage, partly saturated and partly unsaturated, is thus described by nonlinear equations that are not easy to solve. A few analytical solutions exist; they were obtained after several simplifying assumptions. Are they realistic? In this paper, comparisons are made between predictions from analytical solutions and those from numerical resolutions (for saturated and unsaturated seepage) under steady and transient states. The analytical solutions predict a water table and flow rates that differ significantly from those of the numerical resolutions, and are sometimes unrealistic. Corrections to the analytical solutions have already been proposed to account for the vadose zone. Despite such corrections, the published solutions to drainage problems may be inaccurate. In engineering projects where the duration of drainage may be critical for the construction schedule, it is recommended to avoid the analytical equations and to use numerical codes that solve the complete differential equations by taking into account the complete soil characteristic curves for hydraulic conductivity and capillary retention, which can be obtained using permeability tests and capillary-retention tests.
Mobilization of soil loads on buried, polyethylene natural gas pipelines subject to relative axial displacements
Authors: Weerasekara Lalinda , Wijewickreme Dharma
Published: September 2008

The performance of buried, medium-density polyethylene (MDPE) pipes subject to movements relative to the soil in the direction of the pipe axis is investigated by full-scale physical model testing conducted using a large soil box. A new closed-form solution was developed to account for the nonlinear material response of MDPE pipes under axial loading, and the analytical results are compared with the results obtained from the full-scale pipe pullout testing. The closed-form solution provides a rational framework to estimate the response of the pipe (i.e., level of strain, force) and the mobilized frictional length along the pipe for a known relative axial pipe movement. The approach, in turn, could be used to estimate the relative axial movements needed for pipe failure, which is an important consideration in the evaluation of field-performance of pipe systems located in areas of potential ground movement. The methodology is an important initial step towards the development of representative axial soil-springs representing complex pipe–soil interaction encountered in relatively extensible, buried polyethylene (PE) pipe systems subject to soil loading arising from ground movements.
Movement triggers and mechanisms of two earth slides in the Thompson River Valley, British Columbia, Canada
Authors: Eshraghian Arash , Martin C. Derek , Morgenstern Norbert R.
Published: September 2008

Since the construction of the Canadian Pacific Railway and Canadian National Railway main rail lines in western Canada in 1885 and 1905, respectively, both companies have had to contend with 11 large, translational, retrogressive earth slides in the Thompson River Valley south of Ashcroft, British Columbia. The initiation of these slides is associated with the down cutting by the Thompson River through the Quaternary sediments in its valley. The slides move on two subhorizontal weak layers in a glaciolacustrine clay–silt unit within this Quaternary sediment sequence. Transient seepage and stability analyses were conducted for two sample slides, and the results were in agreement with inclinometer and piezometric data. It is concluded that the Thompson River triggers the movements in a drawdown mechanism and (or) erosion mechanism. The Thompson River affects the stability of these slides in three ways: (i) by changing the pore pressure on the rupture surface, (ii) by changing the supporting force on the toe of the slide, and (iii) by changing the geometry of the slides as a result of river erosion. The relative importance of each of these effects depends on the river erosion protection, the depth of the rupture surface, and the amount of river level fluctuation.
A numerical study into lateral cyclic nonlinear soil–pile response
Authors: Allotey Nii , El Naggar M. Hesham
Published: September 2008

Pile foundations are generally designed to resist both axial and lateral loads. Under lateral cyclic loading, the response of the pile foundation is affected by factors such as soil and pile yielding, gapping, and soil cave-in. These factors directly influence the effective lateral stiffness and strength of the foundation and can govern the design. In this paper, two case studies of single piles, one in clay and one in sand, are used to examine the influence of the aforementioned factors on nonlinear cyclic response of piles. The numerical study is conducted using a recently developed beam on a nonlinear Winkler foundation (BNWF) model. The results of the study point to the important role soil cave-in and recompression play in the cyclic soil–pile response, and elucidate how this could particularly be beneficial to piles that develop plastic hinges below ground level.
Probability risk assessment of landslides: A case study at Finneidfjord
Authors: Cassidy Mark J. , Uzielli Marco , Lacasse Suzanne
Published: September 2008

Probabilistic risk assessments are increasingly being considered the most appropriate framework for engineers to systematically base decisions on hazard mitigation issues. This paper aims to show the advantages of a quantitative risk assessment by application to a historical case study. The generalized integrated risk assessment framework has been applied retrospectively to a submarine landslide that occurred in 1996 near the village of Finneidfjord in northern Norway. Over 1 million cubic metres of predominantly quick clay was displaced. Even though it was triggered underwater on the embankment of the Sørfjord, the retrogressive nature of the slide resulted in it encroaching 100–150 m inland. The triggering mechanism is believed to have been the placement of fill, from a nearby tunnelling project, on the foreshore of the embankment. This paper is a retrospective quantitative evaluation of the risk to the neighbouring houses, the persons in those houses, and the persons in open spaces caused by the placement of increasing levels of embankment fill. A probabilistic approach, making use of second-moment modelling and first-order second-moment approximation is adopted. It aims to demonstrate the advantages of this type of risk assessment in understanding complex and integrated hazards, particularly those in populated environments.
Rate of strength increase of unsaturated lateritic soil
Authors: Gui Meen-Wah , Yu Chun-Ming
Published: September 2008

Lateritic soil is a kind of residual soil that is widely distributed in Asia. The water table of the soil is normally very deep so the upper part of the soil is often unsaturated. The largest lateritic soil area in Taiwan is the Linkou terrace. Because the soil here is loosely cohered and consolidated, the problem of slope instability and landslides has always been a major concern. To evaluate the triggering mechanism of landslides, it is necessary to obtain the failure criterion that represents both the saturated and unsaturated conditions of the soil before any analysis is carried out. The parameter required to define such a failure criterion is the rate of shear strength increase, tan φb, which can be obtained via a series of laboratory strength tests in a modified triaxial system under various matric suction levels. Both the intact and remolded lateritic soils taken from Linkou terrace have been tested for this purpose. The results confirm that matric suction in the lateritic soil contributes significantly to the soil shear strength and that intact soil has a higher strength than remolded soil.
Experimental assessment of the response of sands under shear–volume coupled deformation
Authors: Sivathayalan S. , Logeswaran P.
Published: September 2008

An experimental study of the behaviour of an alluvial sand under different strain increment paths representing shear–volume coupled deformation is presented. Both pore pressure and pore volume change simultaneously in these tests. Linear strain paths with different levels of limiting volumetric strain and nonlinear strain paths that simulate different pore pressure boundary conditions were applied to the soil specimen in the laboratory. The strain paths imposed included both expansive and contractive volumetric deformation. Nonuniform excess pore pressures generated during earthquakes (on account of the heterogeneity in natural soils) often lead to such deformation in situ following the end of strong shaking. The shear strength of the soil could decrease significantly when the pore pressure boundary conditions result in volume inflow that leads to a considerable reduction of the effective confining stress. The rate of volume inflow plays a significant role on the resulting stress–strain and pore pressure responses. Both the peak and the minimum shear strength mobilized during the test were significantly dependent on the strain path. The effective stress ratio at the instant of peak pore pressure is independent of the strain path followed, and it is equal to the effective stress ratio noted at the instant of phase transformation in undrained tests.
WEYL ASYMPTOTICS FOR MAGNETIC SCHRÖDINGER OPERATORS AND DE GENNES' BOUNDARY CONDITION
Authors: KACHMAR AYMAN
Published: September 2008

This paper is concerned with the discrete spectrum of the self-adjoint realization of the semi-classical Schrödinger operator with constant magnetic field and associated with the de Gennes (Fourier/Robin) boundary condition. We derive an asymptotic expansion of the number of eigenvalues below the essential spectrum (Weyl-type asymptotics). The methods of proof rely on results concerning the asymptotic behavior of the first eigenvalue obtained in a previous work [10].
EXISTENCE OF ASYMPTOTIC EXPANSIONS IN NONCOMMUTATIVE QUANTUM FIELD THEORIES
Authors: LINHARES C. A. , MALBOUISSON A. P. C. , RODITI I.
Published: September 2008

Starting from the complete Mellin representation of Feynman amplitudes for noncommutative vulcanized scalar quantum field theory, introduced in a previous publication, we generalize to this theory the study of asymptotic behaviors under scaling of arbitrary subsets of external invariants of any Feynman amplitude. This is accomplished in both convergent and renormalized amplitudes.
TIME OPERATORS OF A HAMILTONIAN WITH PURELY DISCRETE SPECTRUM
Authors: ARAI ASAO , MATSUZAWA YASUMICHI
Published: September 2008

We develop a mathematical theory of time operators of a Hamiltonian with purely discrete spectrum. The main results include boundedness, unboundedness and spectral properties of them. In addition, possible connections of a time operator of H with regular perturbation theory are discussed.
THE NONCOMMUTATIVE GEOMETRY OF THE QUANTUM PROJECTIVE PLANE
Authors: D'ANDREA FRANCESCO , DABROWSKI LUDWIK , LANDI GIOVANNI
Published: September 2008

We study the spectral geometry of the quantum projective plane [Formula: see text], a deformation of the complex projective plane ℂP2, the simplest example of spincmanifold which is not spin. In particular, we construct a Dirac operator D which gives a 0+-summable triple, equivariant under Uq(su(3)). The square of D is a central element for which left and right actions on spinors coincide, a fact that is exploited to compute explicitly its spectrum.
WOUND-HEALING PROPERTIES OF TRANSFORMING GROWTH FACTOR β (TGF-β) INDUCIBLE EARLY GENE 1 (TIEG1) KNOCKOUT MICE
Authors: Taguchi Manabu , Moran Steven L. , Zobitz Mark E. , Zhao Chunfeng , Subramaniam Malayannan , Spelsberg Thomas C. , Amadio Peter C.
Published: September 2008

Transforming growth factor beta (TGF-β) has a broad effect on wound healing, but many questions remain about the regulation of TGF-β during the healing process. TGF-β inducible early gene 1 (TIEG1) is a primary response gene for TGF-β that controls the activities of the TGF-β/Smad pathway, the primary TGF-β signaling pathway. The purpose of this study was to investigate the role of TIEG1 in cutaneous wound healing using TIEG1 knockout mice. The wound healing in TIEG1 knockout mice and wild-type controls was evaluated by wound breaking strength, Western blot, and histology at postoperative days 3, 7, and 14. Although re-epithelialization of both groups was similarly complete at day 7, the TIEG1 knockout mice had a significantly lower wound breaking strength than the controls at postoperative day 14. These results suggest that TIEG1 expression may be an important factor involved in the initiation and support of normal cutaneous wound healing.
EIGENMODE OF THE DECISION-BY-MAJORITY PROCESS IN COMPLEX NETWORKS
Authors: UCHIDA MAKOTO , SHIRAYAMA SUSUMU
Published: September 2008

The nature of the dynamics of opinion formation or zero-temperature Ising models modeled as a decision-by-majority process in complex networks is investigated using eigenmode analysis. The Hamiltonian of the system is defined and estimated by eigenvectors of the adjacency matrix constructed from several network models. The rule of the process is assumed to be equivalent to the minimization of the Hamiltonian. The initial and final states of the dynamics are decomposed on the basis of the eigenvectors. The process and the eigenmodes are analyzed by numerical studies. We show that the magnitude of the coefficient for the largest eigenvector at the initial states is the key determinant for the resulting dynamics. We thus prove that the final state of the dynamics can be estimated by the eigenmodes of the initial state.
A REJECTION MECHANISM IN 2D BOUNDED CONFIDENCE PROVIDES MORE CONFORMITY
Authors: HUET S. , DEFFUANT G. , JAGER W.
Published: September 2008

This paper explores the dynamics of attitude change in two dimensions resulting from social interaction. We add a rejection mechanism into the 2D bounded confidence (BC) model proposed by Deffuant et al. (2001). Individuals are characterized by two-dimensional continuous attitudes, each associated with an uncertainty u, supposed constant in this first study. Individuals interact through random pairs. If their attitudes are closer than u on both dimensions, or further than u on both dimensions, or closer than u on one dimension and not further than u + δ u on the other dimension, then the rules of the BC model apply. But if their attitudes are closer than u on one dimension and further than u + δ u on the other dimension, then the individuals are in a dissonant state. They tend to solve this problem by shifting away their close attitudes. The model shows metastable clusters, which maintain themselves through opposite influences of competitor clusters. Our analysis and first experiments support the hypothesis that, for a large range of uncertainty values, the number of clusters grows linearly with the inverse of the uncertainty, whereas this growth is quadratic in the BC model.
COLLECTIVE BEHAVIOR OF EL FAROL ATTENDEES
Authors: ATILGAN CANAN , ATILGAN ALI RANA , DEMIREL GÜVEN
Published: September 2008

Arthur's paradigm of the El Farol bar for modeling bounded rationality and inductive behavior is employed. Manipulating the memory horizon available to the agents and the selection criteria they utilize for prediction algorithms, one can maneuver the mean attendance away from the externally provided threshold. We observe that a transition occurs in the attendance distribution at a critical memory, beyond which a larger part of the crowd becomes more comfortable. Agents' confidence in their algorithms and the delayed feedback of attendance data increase the overall collectivity of the system behavior. It is possible to manipulate the time evolution of the attendance either externally, by providing past data with delay, or internally, if agents postpone algorithm modification upon failure.
THE ECONOMICS OF ATTENTION: MAXIMIZING USER VALUE IN INFORMATION-RICH ENVIRONMENTS
Authors: HUBERMAN BERNARDO A. , WU FANG
Published: September 2008

A distinguishing feature of the information era is the saliency of people's attention as a scarce resource. Unlike an earlier time when information was a valuable resource, its easy availability has shifted the focus to the limited bandwidth that people can devote to ubiquitous media and news. With this in mind, we introduce an automatic configuration mechanism that generates the most relevant information to be presented to limited attention users. It also guarantees to maximize their total expected utility from the information they receive. A computationally efficient algorithm is used to assign an index value to each information item, which then determines whether or not a given item appears in the top list presented to users at a given time.
MIGRATION AS A MECHANISM TO PROMOTE COOPERATION
Authors: HELBING DIRK , YU WENJIAN
Published: September 2008

A unified approach is proposed, which integrates game-theoretical models with models of directed motion. Specifically, strategic interactions in space and imitation of more successful neighboring strategies, as studied by spatial games, are combined with success-driven migration based on "test interactions" or wealth-related "neighborhood tagging." It turns out that such directed migration allows cooperators to evade defectors and (in constrast to purely diffusive motion) also to find other cooperators in order to form clusters ("islands of cooperation"). This can increase the cooperation to a great extent. Moreover, success-driven motion leads to interesting spatiotemporal pattern-formation phenomena, which are clearly different from those produced by previously studied spatial games. Despite the simplicity of the model, the forming patterns appear to realistically represent many stylized facts of social interactions, particularly phenomena such as social networking, urban aggregation, social segregation or turn-taking. Furthermore, migration games offer a game-theoretical explanation of social attraction and repulsion, based on payoff-related mobility, and they display a larger variety than conventional games, as their behavior is not invariant to shifting all payoffs by a constant amount. In summary, the combination of strategic interactions and imitation with models of directed motion has high potential for understanding empirical observations in the social, biological and economic sciences from a game-theoretical point of view. Finally, the breakdown of cooperation in the prisoner's dilemma at high values of temptation is explained by configurational analysis.
EULER SYSTEM FOR COMPRESSIBLE FLUIDS AT A JUNCTION
Authors: COLOMBO RINALDO M. , MAURI CRISTINA
Published: September 2008

Consider n ducts having a common origin and filled with a fluid. Along each duct, the full Euler system describes the evolution of the fluid. At the junction, suitable physical conditions couple the n Euler systems. In this paper we prove the well posedness of the Cauchy problem for the model so obtained, provided the total varaiatio of the initial data is sufficiently small.
EXISTENCE OF SOLUTIONS WITH MOVING PHASE BOUNDARIES IN THERMOELASTICITY
Authors: HATTORI HARUMI
Published: September 2008

We discuss the existence of weak solutions with moving phase boundaries in thermoelasticity related to dynamic phase transitions. One of the goals is to study the dynamical consequence of the stable and metastable states defined in this paper. We use the entropy condition and the kinetic relation as the main admissibility criteria to study the above goals for the Euler equations with nonmonotone constitutive relation. We discuss the case where there are two noninteracting phase boundaries moving in the opposite directions. A modification to treat the case where the two phase boundaries collide is also discussed.
AN ENTROPY BASED GLIMM-TYPE FUNCTIONAL
Authors: CARAVENNA LAURA
Published: September 2008

We consider the Cauchy problem for a scalar conservation law in one space dimension [Formula: see text] We introduce, in this simple setting, a new Glimm-type interaction potential: the time marginal of the entropy dissipation measure of a uniformly convex entropy. We show that the Glimm estimates hold for this functional.
REGULARITY AND GLOBAL STRUCTURE OF SOLUTIONS TO HAMILTON–JACOBI EQUATIONS I: CONVEX HAMILTONIANS
Authors: ZHAO YINCHUAN , TANG TAO , WANG JINGHUA
Published: September 2008

This paper is concerned with the Hamilton–Jacobi (HJ) equations of multidimensional space variables with convex Hamiltonians. Using Hopf's formula (I), we will study the differentiability of the HJ solutions. For any given point, we give a sufficient and necessary condition under which the solutions are Ck smooth in some neighborhood of the point. We also study the characteristics of the HJ equations. It is shown that there are only two kinds of characteristics, one never touches the singularity point, and the other touches the singularity point in a finite time. The sufficient and necessary condition under which the characteristic never touches the singularity point is given. Based on these results, we study the global structure of the set of singularity points for the HJ solutions. It is shown that there exists a one-to-one correspondence between the path connected components of the set of singularity points and the path connected components of a set on which the initial function does not attain its minimum. A path connected component of the set of singularity points never terminates at a finite time. Our results are independent of the particular forms of the equations as long as the Hamiltonians are convex.
THE PLANE SYMMETRIC EINSTEIN-DUST SYSTEM WITH POSITIVE COSMOLOGICAL CONSTANT
Authors: TCHAPNDA S. B.
Published: September 2008

The Einstein equations with a positive cosmological constant are coupled to the pressureless perfect fluid matter in plane symmetry. Under suitable restrictions on the initial data, the resulting Einstein-dust system is proved to have a global classical solution in the future time direction. Some late time asymptotic properties are obtained as well.
Cellular and Molecular Aspects of Rhabdovirus Interactions with Insect and Plant Hosts
Authors: Ammar El-Desouky , Tsai Chi-Wei , Whitfield Anna E. , Redinbaugh Margaret G. , Hogenhout Saskia A.
Published: September 2008

The rhabdoviruses form a large family (Rhabdoviridae) whose host ranges include humans, other vertebrates, invertebrates, and plants. There are at least 90 plant-infecting rhabdoviruses, several of which are economically important pathogens of various crops. All definitive plant-infecting and many vertebrate-infecting rhabdoviruses are persistently transmitted by insect vectors, and a few putative plant rhabdoviruses are transmitted by mites. Plant rhabdoviruses replicate in their plant and arthropod hosts, and transmission by vectors is highly specific, with each virus species transmitted by one or a few related insect species, mainly aphids, leafhoppers, or planthoppers. Here, we provide an overview of plant rhabdovirus interactions with their insect hosts and of how these interactions compare with those of vertebrate-infecting viruses and with the Sigma rhabdovirus that infects Drosophila flies. We focus on cellular and molecular aspects of vector/host specificity, transmission barriers, and virus receptors in the vectors. In addition, we briefly discuss recent advances in understanding rhabdovirus-plant interactions.
Insulin and leptin relations in obesity: a multimedia approach
Authors: Yokaichiya Daniela K. , Galembeck Eduardo , Torres Bayardo B. , Da Silva José Antônio , de Araujo Daniele R.
Published: September 2008

Obesity has been recognized as a worldwide public health problem. It significantly increases the chances of developing several diseases, including Type II diabetes. The roles of insulin and leptin in obesity involve reactions that can be better understood when they are presented step by step. The aim of this work was to design software with data from some of the most recent publications on obesity, especially those concerning the roles of insulin and leptin in this metabolic disturbance. The most notable characteristic of this software is the use of animations representing the cellular response together with the presentation of recently discovered mechanisms on the participation of insulin and leptin in processes leading to obesity. The software was field tested in the Biochemistry of Nutrition web-based course. After using the software and discussing its contents in chatrooms, students were asked to answer an evaluation survey about the whole activity and the usefulness of the software within the learning process. The teaching assistants (TA) evaluated the software as a tool to help in the teaching process. The students' and TAs' satisfaction was very evident and encouraged us to move forward with the software development and to improve the use of this kind of educational tool in biochemistry classes.
A fitness screening model for increasing fitness assessment and research experiences in undergraduate exercise science students
Authors: Brown Gregory A. , Lynott Frank , Heelan Kate A.
Published: September 2008

When students analyze and present original data they have collected, and hence have a cultivated sense of curiosity about the data, student learning is enhanced. It is often difficult to provide students an opportunity to practice their skills, use their knowledge, and gain research experiences during a typical course laboratory. This article describes a model of an out-of-classroom experience during which undergraduate exercise science students provide a free health and fitness screening to the campus community. Although some evidence of the effectiveness of this experience is presented, this is not a detailed evaluation of either the service or learning benefits of the fitness screening. Working in small learning groups in the classroom, students develop hypotheses about the health and fitness of the population to be screened. Then, as part of the health and fitness screening, participants are evaluated for muscular strength, aerobic fitness, body composition, blood pressure, physical activity, and blood cholesterol levels. Students then analyze the data collected during the screening, accept or reject their hypotheses based on statistical analyses of the data, and make in-class presentations of their findings. This learning experience has been used successfully to illustrate the levels of obesity, hypercholesterolemia, and lack of physical fitness in the campus community as well as provide an opportunity for students to use statistical procedures to analyze data. It has also provided students with an opportunity to practice fitness assessment and interpersonal skills that will enhance their future careers.
Glucose as the sole metabolic fuel: a study on the possible influence of teachers' knowledge on the establishment of a misconception among Brazilian high school students
Authors: da Luz Maurício Roberto Motta Pinto
Published: September 2008

In the present work, I investigated the origin of the misconception that glucose is the sole metabolic fuel previously described among Brazilian high school students. The results of a multiple-choice test composed of 24 questions about a broad range of biology subjects were analyzed. The test was part of a contest and was answered by a sample composed of undergraduate students as well as biologists and practicing biology teachers. The majority of the responders had difficulties in recognizing the existence of gluconeogenesis and the possibility of ATP production using other fuels other than carbohydrates. Biology teachers and biologists seemed to either lack the knowledge or present the misconception regarding energy-yielding metabolism found among students. I argue that in both cases, biology teachers are likely to teach metabolism-related subjects in a manner that may contribute to the appearance of the misconception among high school students.
Learning scientific and medical terminology with a mnemonic strategy using an illogical association technique
Authors: Brahler C. Jayne , Walker Diane
Published: September 2008

For students pursuing careers in medical fields, knowledge of technical and medical terminology is prerequisite to being able to solve problems in their respective disciplines and professions. The Dean Vaughn Medical Terminology 350 Total Retention System, also known as Medical Terminology 350 ( 25 ), is a mnemonic instructional and learning strategy that combines mental imagery and keyword mnemonic elaboration processes to help students recall the scientific meaning of Greek and Latin word parts. High school students in Anatomy and Physiology classes at a career technology center were divided into experimental (Medical Terminology 350), control (rote memorization), or combination (Medical Terminology 350 and rote memorization) groups and completed pre- and posttests of standardized word recall tests. Students in the Dean Vaughn Medical Terminology 350 Total Retention System group achieved significantly greater pre- to posttest word recall improvement compared with students in both the rote memorization ( P ≤ 0.0001) and combined rote memorization and Medical Terminology 350 ( P ≤ 0.05) groups. There appeared to be a dose-dependent response as the pre- to posttest gain in word recall scores increased as exposure to the treatment increased.
A reliable whole cell clamp technique
Authors: Li Chenhong
Published: September 2008

This article describes a simple whole cell formation technique that the author invented in teaching and experiments. The implementation of the invented technique is a syringe with a hole and slot. With the newly invented technique, novices will shorten their learning curve and veterans will increase their success rate. The invented technique lightens the labor of the experimenter and improves the success rate and quality of whole cell preparations. The article also provides an idea to design an automated whole cell formation implementation. The tools developed in this technique make the patch-clamp experiment easy to teach and learn.
Challenges in teaching the mechanics of breathing to medical and graduate students
Authors: West John B.
Published: September 2008

The mechanics of breathing has always been a difficult topic for some medical and graduate students. The subject is very quantitative and contains a number of concepts that some students have trouble with, including physical principles such as pressure, flow, volume, resistance, elasticity, and compliance. Apparently, present-day students find the subject more difficult than students of 20 years ago. A possible reason for this is that the teaching of elementary physics in high school and college is now given less emphasis, whereas other topics, such as molecular biology, receive a great deal of attention. Another factor may be that many of us grew up building radios and other such devices, whereas modern students tend to plug in an electronic unit with little idea of its function. Some examples of misconceptions of present-day students who have taken our course are given. To help the weaker students, we now include a primer at the beginning of our handout for the course that covers simple physical principles. Examples of some of the most difficult concepts for students are given.
Teaching ventilation/perfusion relationships in the lung
Authors: Glenny Robb W.
Published: September 2008

This brief review is meant to serve as a refresher for faculty teaching respiratory physiology to medical students. The concepts of ventilation and perfusion matching are some of the most challenging ideas to learn and teach. Some strategies to consider in teaching these concepts are, first, to build from simple to more complex by starting with a single lung unit and then adding additional units representing shunting, mismatch, and deadspace. Second, use simplified analogies, such as a bathtub, to help students conceptualize new ideas. Third, introduce the concept of alveolar to arterial O2 differences and the mechanisms for increasing differences as additional lung units are added. Fourth, use the consistent thread of causes of hypoxemia through the lecture to maintain continuity and provide clinical relevance. Finally, use clinically relevant examples at each step and solidify new concepts by discussing differential diagnoses at the end of the lecture(s).
Truncated ETV1, Fused to Novel Tissue-Specific Genes, and Full-Length ETV1 in Prostate Cancer
Authors: Hermans Karin G. , van der Korput Hetty A. , van Marion Ronald , van de Wijngaart Dennis J. , Ziel-van der Made Angelique , Dits Natasja F. , Boormans Joost L. , van der Kwast Theo H. , van Dekken Herman , Bangma Chris H. , Korsten Hanneke , Kraaij Robert , Jenster Guido , Trapman Jan
Published: September 2008

In this study, we describe the properties of novel ETV1 fusion genes, encoding N-truncated ETV1 (dETV1), and of full-length ETV1, overexpressed in clinical prostate cancer. We detected overexpression of novel ETV1 fusion genes or of full-length ETV1 in 10% of prostate cancers. Novel ETV1 fusion partners included FOXP1, an EST (EST14), and an endogenous retroviral repeat sequence (HERVK17). Like TMPRSS2, EST14 and HERVK17 were prostate-specific and androgen-regulated expressed. This unique expression pattern of most ETV1 fusion partners seems an important determinant in prostate cancer development. In transient reporter assays, full-length ETV1 was a strong transactivator, whereas dETV1 was not. However, several of the biological properties of dETV1 and full-length ETV1 were identical. On stable overexpression, both induced migration and invasion of immortalized nontumorigenic PNT2C2 prostate epithelial cells. In contrast to dETV1, full-length ETV1 also induced anchorage-independent growth of these cells. PNT2C2 cells stably transfected with dETV1 or full-length ETV1 expression constructs showed small differences in induced expression of target genes. Many genes involved in tumor invasion/metastasis, including uPA/uPAR and MMPs, were up-regulated in both cell types. Integrin β3 (ITGB3) was clearly up-regulated by full-length ETV1 but much less by dETV1. Based on the present data and on previous findings, a novel concept of the role of dETV1 and of full-length ETV1 overexpression in prostate cancer is proposed. [Cancer Res 2008;68(18):7541–9]
Flt-1 Signaling in Macrophages Promotes Glioma Growth In vivo
Authors: Kerber Mark , Reiss Yvonne , Wickersheim Anke , Jugold Manfred , Kiessling Fabian , Heil Matthias , Tchaikovski Vadim , Waltenberger Johannes , Shibuya Masabumi , Plate Karl H. , Machein Marcia Regina
Published: September 2008

Several lines of evidence indicate that Flt-1, a fms-like tyrosine kinase receptor, which binds to vascular endothelial growth factor (VEGF)-A, VEGF-B, and PlGF, is a positive regulator of angiogenesis in the context of tumor growth and metastasis. However, the molecular basis of its action is still not clear. Besides endothelial cells, Flt-1 is also expressed by other different cell types, including myeloid hematopoeitic cells (monocytes and macrophages). To examine the functions of Flt-1 expressed by bone marrow–derived myeloid cells in supporting tumor growth and angiogenesis, Flt-1 tyrosine kinase–deficient (Flt-1 TK−/−) bone marrow cells were transplanted into lethally irradiated syngeneic recipients. After hematopoietic reconstitution, we orthotopically implanted syngeneic wild-type glioma cells or glioma cells overexpressing either VEGF164 or PlGF-2. Loss of Flt-1 signaling in bone marrow–derived myeloid cells led to a significant decrease in tumor volume and vascularization in gliomas. VEGF but not PlGF overexpressed by glioma cells restored the tumor growth rate in Flt-1 TK−/− bone marrow chimera. VEGF and PlGF overexpression by tumor cells induced an accumulation of bone marrow–derived myeloid cells into tumor tissue. This infiltration was decreased in tumors grown in Flt-1 TK−/− bone marrow chimeras. When investigating chemokines and growth factors involved in myeloid cell recruitment, we determined elevated SDF-1/CXCL12 levels in VEGF- and PlGF-overexpressing tumors. Collectively, these results suggest that Flt-1 signaling in myeloid cells is essential to amplify the angiogenic response and to promote glioma growth. [Cancer Res 2008;68(18):7342–51]
Targeting V600EB-Raf and Akt3 Using Nanoliposomal-Small Interfering RNA Inhibits Cutaneous Melanocytic Lesion Development
Authors: Tran Melissa A. , Gowda Raghavendra , Sharma Arati , Park Eun-Joo , Adair James , Kester Mark , Smith Nadine Barrie , Robertson Gavin P.
Published: September 2008

Most events promoting early melanoma development are yet to be identified, but deregulation of the B-Raf and Akt3 signaling cascades is an important regulator of this process. Approximately 90% of normal moles and ∼60% of early invasive cutaneous melanomas contain a T1799A B-Raf mutation (V600EB-Raf), leading to 10 times higher enzyme activity and constitutive activation of the mitogen-activated protein kinase pathway. Furthermore, ∼70% of melanomas have elevated Akt3 signaling due to increased gene copy number and PTEN loss. Therefore, targeting V600EB-Raf and Akt3 signaling is necessary to prevent or treat cutaneous melanocytic lesions. Agents specifically targeting these proteins are needed, having fewer side effects than those inhibiting both normal and mutant B-Raf protein or targeting all three Akt isoforms. In this study, a unique nanoliposomal-ultrasound–mediated approach has been developed for delivering small interfering RNA (siRNA) specifically targeting V600EB-Raf and Akt3 into melanocytic tumors present in skin to retard melanoma development. Novel cationic nanoliposomes stably encapsulate siRNA targeting V600EB-Raf or Akt3, providing protection from degradation and facilitating entry into melanoma cells to decrease expression of these proteins. Low-frequency ultrasound using a lightweight four-cymbal transducer array enables penetration of nanoliposomal-siRNA complex throughout the epidermal and dermal layers of laboratory-generated or animal skin. Nanoliposomal-mediated siRNA targeting of V600EB-Raf and Akt3 led to a cooperatively acting ∼65% decrease in early or invasive cutaneous melanoma compared with inhibition of each singly with negligible associated systemic toxicity. Thus, cationic nanoliposomes loaded with siRNA targeting V600EB-Raf and Akt3 provide an effective approach for targeted inhibition of early or invasive cutaneous melanomas. [Cancer Res 2008;68(18):7638–49]
RhoC Promotes Metastasis via Activation of the Pyk2 Pathway in Prostate Cancer
Authors: Iiizumi Megumi , Bandyopadhyay Sucharita , Pai Sudha K. , Watabe Misako , Hirota Shigeru , Hosobe Sadahiro , Tsukada Taisei , Miura Kunio , Saito Ken , Furuta Eiji , Liu Wen , Xing Fei , Okuda Hiroshi , Kobayashi Aya , Watabe Kounosuke
Published: September 2008

RhoC is a member of the Ras-homologous family of genes which have been implicated in tumorigenesis and tumor progression. However, the exact role of RhoC is controversial and is yet to be clarified. We have examined the effect of RhoC on prostate tumor cells and found that RhoC had no effect on cell proliferation in vitro or on tumor growth in mice. However, RhoC significantly enhanced the metastatic ability of the tumor cells in these animals, suggesting that RhoC affects only the metastasis but not the growth of prostate tumor cells. The results of our immunohistochemical analyses on tumor specimens from 63 patients with prostate cancer indicate that RhoC expression had no significant correlation with Gleason grade. However, the expression of RhoC showed significant positive correlation with both lymph node and distant metastasis, and it was inversely correlated with patient survival. We also found that RhoC significantly augmented the invasion and motility of prostate tumor cells by activating matrix metalloproteinases 2 and 9 (MMP2 and MMP9) in vitro. The results of our antibody array analysis for signal molecules revealed that RhoC significantly activated kinases including mitogen-activated protein kinase (MAPK), focal adhesion kinase (FAK), Akt, and Pyk2. Inhibition of Pyk2 kinase blocked the RhoC-dependent activation of FAK, MAPK, and Akt, followed by the suppression of MMP2 and MMP9. Inhibitors of both MAPK and Akt also significantly blocked the activities of these MMPs. Therefore, our results indicate that RhoC promotes tumor metastasis in prostate cancer by sequential activation of Pyk2, FAK, MAPK, and Akt followed by the up-regulation of MMP2 and MMP9, which results in the stimulation of invasiveness of tumor cells. [Cancer Res 2008;68(18):7613–20]
Knockdown of the Transforming Growth Factor-β Type III Receptor Impairs Motility and Invasion of Metastatic Cancer Cells
Authors: Criswell Tracy L. , Dumont Nancy , Barnett Joey V. , Arteaga Carlos L.
Published: September 2008

The transforming growth factor-β (TGF-β) signaling pathway plays dual roles in epithelial cell tumorigenesis. TGF-β is initially growth inhibitory, but as tumorigenesis progresses, TGF-β becomes prometastatic. Although the role of the types I and II TGF-β receptors is fairly well established, the role of the ubiquitously expressed TGF-β type III receptor (TβRIII) in tumorigenesis is less defined. To examine the role of TβRIII in breast cancer cells, we stably expressed short hairpin RNAs specific to TβRIII in MDA-231 human breast cancer cells and mouse mammary carcinoma cells expressing the polyomavirus middle T oncogene (PMTLuc). MDA-231 and PMTLuc cells with down-regulated TβRIII expression (231-kd; PMTLuc-kd) exhibited decreased growth rate, motility, and invasion into Matrigel, as well as an increase in apoptosis, compared with control cells. MDA-231 xenografts established in nude mice metastasized, whereas tumors made by 231-kd cells did not. Nuclear factor-κB (NF-κB) activity, which is known to regulate cell growth and motility, was lower in the MDA-231 and PMTLuc knockdown cells compared with control cells. Transfection of an expression vector encoding constitutively active IKK2 into the 231-kd cells restored the ability of TβRIII-deficient cells to invade Matrigel and decreased their basal level of apoptosis. These data indicate that TβRIII differentially regulates cell growth, motility, and invasion in tumorigenic MDA-231 and PMTLuc cells and that these growth changes occur through the modulation of NF-κB activity. [Cancer Res 2008;68(18):7304–12]
Nkx3-1 and LEF-1 Function as Transcriptional Inhibitors of Estrogen Receptor Activity
Authors: Holmes Kelly A. , Song Jun S. , Liu Xiaole S. , Brown Myles , Carroll Jason S.
Published: September 2008

Estrogen receptor (ER)-associated cofactors and cooperating transcription factors are one of the primary components determining transcriptional activity of estrogen target genes and may constitute potential therapeutic targets. Recent mapping of ER-binding sites on a genome-wide scale has provided insight into novel cooperating factors based on the enrichment of transcription factor motifs within the ER-binding sites. We have used the ER-binding sites in combination with sequence conservation to identify the statistical enrichment of Nkx and LEF motifs. We find that Nkx3-1 and LEF-1 bind to several ER cis-regulatory elements in vivo, but they both function as transcriptional repressors of estrogen signaling. We show that Nkx3-1 and LEF-1 can inhibit ER binding to chromatin, suggesting competition for common chromatin-binding regions. These data provide insight into the role of Nkx3-1 and LEF-1 as potential regulators of the hormone response in breast cancer. [Cancer Res 2008;68(18):7380–5]