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Kinds of Field. Selected AbstractsSilicon transport under rotating and combined magnetic fields in liquid phase diffusion growth of SiGeCRYSTAL RESEARCH AND TECHNOLOGY, Issue 4 2010N. Armour Abstract The effect of applied rotating and combined (rotating and static) magnetic fields on silicon transport during the liquid phase diffusion growth of SiGe was experimentally studied. 72-hour growth periods produced some single crystal sections. Single and polycrystalline sections of the processed samples were examined for silicon composition. Results show that the application of a rotating magnetic field enhances silicon transport in the melt. It also has a slight positive effect on flattening the initial growth interface. For comparison, growth experiments were also conducted under combined (rotating and static) magnetic fields. The processed samples revealed that the addition of static field altered the thermal characteristics of the system significantly and led to a complete melt back of the germanium seed. Silicon transport in the melt was also enhanced under combined fields compared with experiments with no magnetic field. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Statistical theory of weak field thermoremanent magnetization in multidomain particle ensemblesGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2003Karl Fabian SUMMARY A non-equilibrium statistical theory of multidomain thermoremanent magnetization (TRM) is developed, which describes thermal magnetization changes as continuous inhomogeneous Markov processes. The proposed theory relies on three very general physical properties of TRM: (a) The probability that a magnetization state Sj is transformed during an infinitesimal temperature change into state Si depends only on external conditions and on Sj, but not on previously assumed states. (b) Due to time inversion symmetry of the Maxwell equations, the magnetic energies are invariant with respect to inversion of all spins in zero field. (c) The probability that an energy barrier between two magnetization states is overcome during a thermal process is governed by Boltzmann statistics. From these properties, the linearity of TRM with field is derived for generic multidomain particle ensembles. The general validity of Thellier's law of additivity of partial TRM's in weak fields is established and a method for proving a large class of similar additivity laws is developed. The theory allows consistent treatment of blocking and unblocking of remanence in multidomain particle ensembles and naturally explains apparent differences between blocking and unblocking temperatures. [source] Lipopolysaccharide is a frequent and significant contaminant in microglia-activating factorsGLIA, Issue 1 2008Jonathan R. Weinstein Abstract Lipopolysaccharide (LPS/endotoxin) is a potent immunologic stimulant. Many commercial-grade reagents used in research are not screened for LPS contamination. LPS induces a wide spectrum of proinflammatory responses in microglia, the immune cells of the brain. Recent studies have demonstrated that a broad range of endogenous factors including plasma-derived proteins and bioactive phospholipids can also activate microglia. However, few of these studies have reported either the LPS levels found in the preparations used or the effect of LPS inhibitors such as polymyxin B (PMX) on factor-induced responses. Here, we used the Limulus amoebocyte lysate assay to screen a broad range of commercial- and pharmaceutical-grade proteins, peptides, lipids, and inhibitors commonly used in microglia research for contamination with LPS. We then characterized the ability of PMX to alter a representative set of factor-induced microglial activation parameters including surface antigen expression, metabolic activity/proliferation, and NO/cytokine/chemokine release in both the N9 microglial cell line and primary microglia. Significant levels of LPS contamination were detected in a number of commercial-grade plasma/serum- and nonplasma/serum-derived proteins, phospholipids, and synthetic peptide preparations, but not in pharmaceutical-grade recombinant proteins or pharmacological inhibitors. PMX had a significant inhibitory effect on the microglia-activating potential of a number of commercial-, but not pharmaceutical-grade, protein preparations. Novel PMX-resistant responses to ,2 -macroglobulin and albumin were incidentally observed. Our results indicate that LPS is a frequent and significant contaminant in commercial-grade preparations of previously reported microglia-activating factors. Careful attention to LPS levels and appropriate controls are necessary for future studies in the neuroinflammation field. © 2007 Wiley-Liss, Inc. [source] Noninvasive diagnosis and monitoring of nonalcoholic steatohepatitis: Present and future,HEPATOLOGY, Issue 2 2007Anna Wieckowska Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease in the United States, and its prevalence is increasing worldwide. It currently affects approximately 30% of adults and 10% of children in the United States. NAFLD represents a wide spectrum of conditions ranging from simple fatty liver which in general follows a benign nonprogressive clinical course, to nonalcoholic steatohepatitis (NASH), which is a more serious form of NAFLD that may progress to cirrhosis and end-stage liver disease. At present, a liver biopsy remains the only reliable way to diagnose NASH and establish the presence of fibrosis. Current noninvasive clinically available tests lack accuracy and reliability. In light of the dramatic increase in the prevalence of NAFLD in conjunction with the significant research effort in developing novel therapies for patients with NASH, noninvasive, simple, reproducible, and reliable biomarkers are greatly needed. They will not only help in the diagnosis of NASH, but also be useful for assessment of treatment response and prognosis and remain a research priority in the NAFLD field. (HEPATOLOGY 2007;46:582,589.) [source] Sentinel lymph node biopsy in patients with melanoma and breast cancerINTERNAL MEDICINE JOURNAL, Issue 9 2001R. F. Uren Abstract Sentinel lymph node biopsy (SNLB) is a new method for staging regional node fields in patients with cancers that have a propensity to metastasise to lymph nodes. The majority of early experience has been obtained in patients with melanoma and breast cancer. The technique requires the close cooperation of nuclear medicine physicians, surgical oncologists and histopathologists to achieve the desired accuracy. It involves: (i) identification of all lymph nodes that directly drain a primary tumour site (the sentinel nodes) by the use of pre-operative lymphoscintigraphy, (ii) selective excision of these nodes by the surgeon, guided by pre-operative blue dye injection and a gamma detecting probe intra-operatively and (iii) careful histological examination of the sentinel nodes by the histopathologist using serial sections and immunohistochemical stains. If the nodes are normal it can be inferred with a high degree of accuracy that all nodes in the node field are normal. This means that radical dissections of draining node fields can be avoided in patients with normal lymph nodes. A further advantage of lyamphatic mapping is that drainage to sentinel nodes in unusual locations is identified, leading to more accurate nodal staging than could be achieved with routine dissection of the closest node field. (Intern Med J 2001; 31: 547,553) [source] Theoretical calculations of transition probabilities and oscillator strengths for Ti III and Ti IVINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 2 2009Tian-Yi Zhang Abstract Due to the complicated electronic configuration of atoms and ions of the transition metal elements, the studies for properties such as transition probabilities and oscillator strengths for these atoms and ions are not systematic. Because of the existence in a variety of stellar objects and wide use in the field of astrophysics, titanium has long been of interest for many researchers. In this article within the Weakest Bound Electron Potential Model (WBEPM) theory, comprehensive set of calculations for transition probabilities and oscillator strengths for Ti III and Ti IV are performed. Many of our results had no previous experimental or theoretical values, so these predictive results could be of some value to the workers in this field. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source] Dipole induced photodetachment dynamics of halide anionsINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 1 2008Chandan Kumar MondalArticle first published online: 1 MAY 200 Abstract In this article the dynamics of photodetachment from closed shell anion in the presence of two color (bichromatic) laser field have been explored in the context of polar environmental situation. The electronic states of halide ions are modeled by a one dimensional Hamiltonian with a potential V(x) = ,V0e. The two parameters V0 and , are fixed by requiring V(x) to reproduce the experimentally observed ground state ionization energy of the halide ion concerned. The potential so generated are shown to support only one bound state. The time-dependent Fourier grid Hamiltonian method is used to follow the detachment dynamics with fairly high intensities of light. The environmental effects on the dynamics are sought to be modeled by two ways i) allowing the well depth (V0) to fluctuate randomly V0(t) = V0[1+,VR(t)]; R(t) randomly fluctuates between +1 and ,1 with time, when ,V (strength of fluctuation) is fixed and ii) in the presence of perturbation produced by a neighboring solvent dipole, which changes the effective potential. The detachment rate constant is studied as a function of important system parameters of the used light field. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008 [source] Label-free biochemical characterization of stem cells using vibrational spectroscopyJOURNAL OF BIOPHOTONICS, Issue 11 2009James W. Chan Abstract Raman and infrared (IR) spectroscopy are two complementary vibrational spectroscopic techniques that have experienced a tremendous growth in their use in biological and biomedical research. This is, in large part, due to their unique capability of providing label-free intrinsic chemical information of living biological samples at tissue, cellular, or sub-cellular resolutions. This article reviews recent developments in applying these techniques for the characterization of stem cells. A discussion of the potential for these methods to address some of the major challenges in stem cell research is presented, as well as the technological and scientific advancements that are needed to progress the knowledge in the field. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Eleven rules for a more successful clinical psychologyJOURNAL OF CLINICAL PSYCHOLOGY, Issue 9 2005Steven C. Hayes The recommendations put forth in the target article, "Twenty-First Century Graduate Education in Clinical Psychology: A Four Level Matrix Model" (C.R. Snyder & T.R. Elliott, this issue), should be regarded in the context of the large need to develop a more progressive and effective discipline. No amount of "brute force" education and empiricism is certain to solve the problems of the scope of our field identified by the authors. Eleven rules are offered and defended that may lead to a more practically and empirically successful field. © 2005 Wiley Periodicals, Inc. J Clin Psychol. [source] Ranking institutional settings based on publications in community psychology journalsJOURNAL OF COMMUNITY PSYCHOLOGY, Issue 8 2007Leonard A. Jason Two primary outlets for community psychology research, the American Journal of Community Psychology and the Journal of Community Psychology, were assessed to rank institutions based on publication frequency and scientific influence of publications over a 32-year period. Three specific periods were assessed (1973,1983, 1984,1994, 1995,2004). Findings indicate that there were a large group of institutions that published articles during these periods. Those academic institutions that had the most published articles as well as the largest influence, based on citations by other authors, were identified. Using archival data from the community psychology literature represents one approach for identifying those settings that made substantial contributions to the development and growth of the field. © 2007 Wiley Periodicals, Inc. J Comm Psychol 35: 967,979, 2007. [source] A semiempirical free energy force field with charge-based desolvationJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 6 2007Ruth Huey Abstract The authors describe the development and testing of a semiempirical free energy force field for use in AutoDock4 and similar grid-based docking methods. The force field is based on a comprehensive thermodynamic model that allows incorporation of intramolecular energies into the predicted free energy of binding. It also incorporates a charge-based method for evaluation of desolvation designed to use a typical set of atom types. The method has been calibrated on a set of 188 diverse protein,ligand complexes of known structure and binding energy, and tested on a set of 100 complexes of ligands with retroviral proteases. The force field shows improvement in redocking simulations over the previous AutoDock3 force field. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007 [source] Axon or dendrite? cell biology and molecular pathways for neuronal cell asymmetryJOURNAL OF NEUROSCIENCE RESEARCH, Issue 3 2008Masashi Kishi Abstract Young neurons polarize by specializing axons and dendrites from immature neurites. After synapse formations, they transmit electrical activity along the axon-dendrite axis, thereby working as functional units of the neural circuits. This axon-dendrite asymmetry is referred to as neuronal polarity. Although a great number of cell biological studies in vitro had been performed, little was known about the molecular events that establish the polarity. In the last several years, rapid advancement in molecular and genetic studies has unraveled the multiple signaling pathways. This paper summarizes current perspectives on the cell and molecular biological mechanisms of the neuronal polarization, to clarify future directions in this growing research field. © 2007 Wiley-Liss, Inc. [source] Polymer chemistry in flow: New polymers, beads, capsules, and fibersJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 22 2006Jeremy L. Steinbacher Abstract The union between polymer science and microfluidics is reviewed. Fluids in microreactors allow the synthesis of a wide range of polymeric materials with unique properties. We begin by discussing the important fluid dynamics that dominate the behavior of fluids on the micrometer scale. We then progress through a comprehensive analysis of the polymeric materials synthesized to date. This highlight concludes with an overview of the methods used to make microreactors. We enthusiastically endorse microreactors as a powerful approach to making materials with controlled properties, although we have tried to provide a critical eye to help the nonexpert enter the field. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6505,6533, 2006 [source] Enhancing the quality of argumentation in school scienceJOURNAL OF RESEARCH IN SCIENCE TEACHING, Issue 10 2004Jonathan Osborne The research reported in this study focuses on the design and evaluation of learning environments that support the teaching and learning of argumentation in a scientific context. The research took place over 2 years, between 1999 and 2001, in junior high schools in the greater London area. The research was conducted in two phases. In phase 1, working with a group of 12 science teachers, the main emphasis was to develop sets of materials and strategies to support argumentation in the classroom, and to support and assess teachers' development with teaching argumentation. Data were collected by video- and audio-recording the teachers' attempts to implement these lessons at the beginning and end of the year. During this phase, analytical tools for evaluating the quality of argumentation were developed based on Toulmin's argument pattern. Analysis of the data shows that there was significant development in the majority of teachers use of argumentation across the year. Results indicate that the pattern of use of argumentation is teacher-specific, as is the nature of the change. In phase 2 of the project, the focus of this paper, teachers taught the experimental groups a minimum of nine lessons which involved socioscientific or scientific argumentation. In addition, these teachers taught similar lessons to a comparison group at the beginning and end of the year. The purpose of this research was to assess the progression in student capabilities with argumentation. For this purpose, data were collected from 33 lessons by video-taping two groups of four students in each class engaging in argumentation. Using a framework for evaluating the nature of the discourse and its quality developed from Toulmin's argument pattern, the findings show that there was improvement in the quality of students' argumentation. This research presents new methodological developments for work in this field. © 2004 Wiley Periodicals, Inc. J Res Sci Teach 41: 994,1020, 2004 [source] Cheiron's origins: Personal recollections and a photographJOURNAL OF THE HISTORY OF THE BEHAVIORAL SCIENCES, Issue 2 2004Elizabeth ScarboroughArticle first published online: 19 MAR 200 When the Cheiron Society convened at the University of New Hampshire for its thirty-fifth annual meeting in June 2003, members were returning to the site where the proposal to establish a new scholarly organization to promote research in the history of the behavioral and social sciences originated in the summer of 1968. I was witness to Cheiron's birthing and have been closely involved in its evolution over the years, and so was asked to comment on the circumstances that produced what has become a vibrant source of stimulation and support for those of us interested in the field. (For other published accounts of the Institute and Cheiron's founding see Brozek, Watson, & Ross, 1969, 1970; Goodman, 1979, 1982; Watson, 1972, 1975; and Weyant, 1968.) © 2004 Wiley Periodicals, Inc. [source] Spontaneous bremsstrahlung effect in the nonrelativistic electron scattering by a nucleus in the field of pulsed light waveLASER PHYSICS LETTERS, Issue 6 2009A.A. Lebed' Abstract The theory of nonresonant spontaneous bremsstrahlung by a nonrelativistic electron scattered by a nucleus in the field of a pulsed light wave is developed. The electron interaction with a Coulomb potential of a nucleus is considered in the first order of perturbation theory (the Born approximation), and the interaction with an external pulsed field is taken into account accurately. The approximation is examined when the pulsewidth is considerably greater than the characteristic time of wave oscillations. For the range of moderately strong fields the analytic expression for the nonresonant differential cross-section was obtained, which has the form of a sum over partial differential crosssections. It is shown, that in the case of nonrelativistic electron energy the partial cross-section is not factorable on the crosssection of electron-nucleus spontaneous bremsstrahlung in the absence of the external field and the emission-absorption probability of a certain number of wave photons. It is concluded, that the total cross-section of spontaneous bremsstrahlung of an electron scattered by a nucleus in the field of pulsed light wave summing over all possible partial processes differs essentially from the cross-section of electron-nucleus spontaneous bremsstrahlung in the absence of the external field. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Resonant scattering of a photon by an electron in the field of a circularly polarized electromagnetic waveLASER PHYSICS LETTERS, Issue 4 2005A. I. Voroshilo Abstract This paper presents, for general relativistic case, a theoretical study of Compton effect in the field of a circularly polarized wave under resonant condition , resonances related to a virtual intermediate particle that falls within the mass shell. We derive the expressions for the resonant amplitude and the differential cross section when the invariant intensity parameter of the wave is small (, , 1) and absent interference of the scattering and annihilation reaction amplitudes. It is demonstrated that the resonant cross section of scattering may be several orders of magnitude higher than the cross section of Compton effect in the absence of the external field. (© 2005 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] GeV-acceleration of electron by a superintense ultrashort laser pulseLASER PHYSICS LETTERS, Issue 8 2004A. Bahari Abstract New mechanism of laser acceleration of a charged particle is discovered and explained. Particle acceleration with focused beam of superintense ultrashort laser pulse is determined by a combination of ponderomotive forces at rising and falling edges of laser pulse and a longitudinal component of laser electric field. We found that acceleration of electron, which moves along the laser wavevector, is crucially depends on whether or not the electron reaches the region z , zR behind the laser focus (here zR is the Rayleigh length). Interpretation of this effect consists in that the laser longitudinal electric field at the electron trajectory in this region is a unidirectional one (oscillatory in the case of laser linear polarization and slowly varying in the case of laser circular polarization). Due to this effect it is possible to overcome the negative influence of a phase slippage in the particle- wave interaction, which substantially suppresses electron acceleration. We revealed also that the physical reason of a unidirectional influence of laser longitudinal electric field on accelerating electron in the region z , zR consists in the difference in phase velocities of transverse and longitudinal components of a focused laser field. Owing to this mechanism, lasers of ultimate present-day parameters enable electron acceleration up to the energy , , 1 GeV. Moreover, electron acceleration along the laser wavevector (in contrast to techniques currently considered) is not sensitive to field initial phase (there is no bunch effect), it is possible to accelerate slow electrons (electrons need not to be preaccelerated to relativistic velocities), and there are no problems with a removal of accelerated electron from the laser field. (© 2004 by ASTRO, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Analytical strategies for identifying drug metabolitesMASS SPECTROMETRY REVIEWS, Issue 3 2007Chandra Prakash Abstract With the dramatic increase in the number of new chemical entities (NCEs) arising from combinatorial chemistry and modern high-throughput bioassays, novel bioanalytical techniques are required for the rapid determination of the metabolic stability and metabolites of these NCEs. Knowledge of the metabolic site(s) of the NCEs in early drug discovery is essential for selecting compounds with favorable pharmacokinetic credentials and aiding medicinal chemists in modifying metabolic "soft spots". In development, elucidation of biotransformation pathways of a drug candidate by identifying its circulatory and excretory metabolites is vitally important to understand its physiological effects. Mass spectrometry (MS) and nuclear magnetic resonance (NMR) have played an invaluable role in the structural characterization and quantification of drug metabolites. Indeed, liquid chromatography (LC) coupled with atmospheric pressure ionization (API) MS has now become the most powerful tool for the rapid detection, structure elucidation, and quantification of drug-derived material within various biological fluids. Often, however, MS alone is insufficient to identify the exact position of oxidation, to differentiate isomers, or to provide the precise structure of unusual and/or unstable metabolites. In addition, an excess of endogenous material in biological samples often suppress the ionization of drug-related material complicating metabolite identification by MS. In these cases, multiple analytical and wet chemistry techniques, such as LC-NMR, enzymatic hydrolysis, chemical derivatization, and hydrogen/deuterium-exchange (H/D-exchange) combined with MS are used to characterize the novel and isomeric metabolites of drug candidates. This review describes sample preparation and introduction strategies to minimize ion suppression by biological matrices for metabolite identification studies, the application of various LC-tandem MS (LC-MS/MS) techniques for the rapid quantification and identification of drug metabolites, and future trends in this field. © 2007 Wiley Periodicals, Inc., Mass Spec Rev [source] Multiple Dedekind sums and relative class number formulaeMATHEMATISCHE NACHRICHTEN, Issue 14 2005Mikihito Hirabayashi Abstract We construct some multiple Dedekind sums and relate them to the relative class number of an imaginary abelian number field. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Maslovian Lagrangian surfaces of constant curvature in complex projective or complex hyperbolic planesMATHEMATISCHE NACHRICHTEN, Issue 11 2005Bang-Yen Chen Abstract A Lagrangian submanifold is called Maslovian if its mean curvature vector H is nowhere zero and its Maslov vector field JH is a principal direction of AH . In this article we classify Maslovian Lagrangian surfaces of constant curvature in complex projective plane CP2 as well as in complex hyperbolic plane CH2. We prove that there exist 14 families of Maslovian Lagrangian surfaces of constant curvature in CP2 and 41 families in CH2. All of the Lagrangian surfaces of constant curvature obtained from these families admit a unit length Killing vector field whose integral curves are geodesics of the Lagrangian surfaces. Conversely, locally (in a neighborhood of each point belonging to an open dense subset) every Maslovian Lagrangian surface of constant curvature in CP2 or in CH2 is a surface obtained from these 55 families. As an immediate by-product, we provide new methods to construct explicitly many new examples of Lagrangian surfaces of constant curvature in complex projective and complex hyperbolic planes which admit a unit length Killing vector field. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Melanocortin ligands: 30 years of structure,activity relationship (SAR) studiesMEDICINAL RESEARCH REVIEWS, Issue 3 2004Jerry Ryan Holder Abstract The challenge of peptide and peptidomimetic research is the development of methods and techniques to improve the biological properties of native peptides and to convert peptide ligands into non-peptide compounds. Improved biological properties of peptides includes enhancement of stability, potency, and receptor selectivity, for both in vivo and in vitro applications. The design of a ligand with specific activity and desired biological properties is a complex task, and, to accomplish this objective, knowledge about putative interactions between a ligand and the corresponding receptor will be valuable. This includes interactions for both the binding and signal transduction processes. Structure,activity relationship (SAR) studies involve systematic modification of a lead peptide and are designed to provide insight into potential interactions involved in the formation of the ligand,receptor complex. It is desirable to have knowledge about both favorable and unfavorable processes that may occur in putative ligand,receptor interactions that result in either receptor stimulation or inhibition. Herein, we discuss various SAR studies that have involved melanocortin peptides over three decades and the information these studies have provided to the melanocortin field. © 2004 Wiley Periodicals, Inc. Med Res Rev, 24, No. 3, 325,356, 2004 [source] Selection criteria for drug-like compoundsMEDICINAL RESEARCH REVIEWS, Issue 3 2003Ingo Muegge Abstract The fast identification of quality lead compounds in the pharmaceutical industry through a combination of high throughput synthesis and screening has become more challenging in recent years. Although the number of available compounds for high throughput screening (HTS) has dramatically increased, large-scale random combinatorial libraries have contributed proportionally less to identify novel leads for drug discovery projects. Therefore, the concept of ,drug-likeness' of compound selections has become a focus in recent years. In parallel, the low success rate of converting lead compounds into drugs often due to unfavorable pharmacokinetic parameters has sparked a renewed interest in understanding more clearly what makes a compound drug-like. Various approaches have been devised to address the drug-likeness of molecules employing retrospective analyses of known drug collections as well as attempting to capture ,chemical wisdom' in algorithms. For example, simple property counting schemes, machine learning methods, regression models, and clustering methods have been employed to distinguish between drugs and non-drugs. Here we review computational techniques to address the drug-likeness of compound selections and offer an outlook for the further development of the field. © 2003 Wiley Periodicals, Inc. Med Res Rev, 23, No. 3, 302-321, 2003 [source] Can we stop transgenes from taking a walk on the wild side?MOLECULAR ECOLOGY, Issue 5 2008KATRINA M. DLUGOSCH Abstract Whether the potential costs associated with broad-scale use of genetically modified organisms (GMOs) outweigh possible benefits is highly contentious, including within the scientific community. Even among those generally in favour of commercialization of GM crops, there is nonetheless broad recognition that transgene escape into the wild should be minimized. But is it possible to achieve containment of engineered genetic elements in the context of large scale agricultural production? In a previous study, Warwick et al. (2003) documented transgene escape via gene flow from herbicide resistant (HR) canola (Brassica napus) into neighbouring weedy B. rapa populations (Fig. 1) in two agricultural fields in Quebec, Canada. In a follow-up study in this issue of Molecular Ecology, Warwick et al. (2008) show that the transgene has persisted and spread within the weedy population in the absence of selection for herbicide resistance. Certainly a trait like herbicide resistance is expected to spread when selected through the use of the herbicide, despite potentially negative epistatic effects on fitness. However, Warwick et al.'s findings suggest that direct selection favouring the transgene is not required for its persistence. So is there any hope of preventing transgene escape into the wild? Figure 1. Weedy Brassica rapa (orange flags) growing in a B. napus field. (Photo: MJ Simard) [source] The nonmotor symptoms of Parkinson's disease,An overview,MOVEMENT DISORDERS, Issue S1 2010FRACP, Shen-Yang Lim MBBS Abstract Nonmotor symptoms (NMS) are very common in Parkinson's disease (PD) and may result in significant disability. The increased focus on these important clinical features represents a major advance in the care of PD patients. In this article, we provide an overview of recent developments in the field. © 2010 Movement Disorder Society [source] Essential tremor , Neurodegenerative or nondegenerative disease towards a working definition of ET,MOVEMENT DISORDERS, Issue 14 2009Günther Deuschl MD Abstract Essential tremor (ET) is a syndrome of tremor in posture and movement, but recent studies have revealed additional cerebellar motor disturbances, cognitive disturbances, personality changes, hearing loss, and olfactory deficits. Even dementia and shortened life expectancy were found in one cohort. Recent postmortem studies have found limited Lewy body pathology in some patients and Purkinje cell loss with torpedoes and Bergmann gliosis in others. These findings have led to the hypothesis that ET is a syndrome produced by at least two neurodegenerative diseases with more widespread clinical consequences than previously appreciated. We review the evidence for and against this hypothesis and conclude that studies purporting to support this hypothesis have failed to control for age-associated comorbidities, depression, medications, and other confounding factors. We propose the alternative hypothesis that abnormal neuronal oscillation is the fundamental abnormality in ET, and the well-documented cerebellar signs and symptoms, the controversial non-motor signs, and even the cerebellar pathology of ET could be caused by this oscillation. A major problem for many studies is the lack of a diagnostic gold standard. Lacking such a standard, we propose a subclassification of ET into three categories: hereditary ET, sporadic ET, and senile ET, which we believe will help researchers resolve many of the controversies in this field. © 2009 Movement Disorder Society [source] Small-worlds: A review of recent booksNETWORKS: AN INTERNATIONAL JOURNAL, Issue 3 2003I. Frommer Abstract Small-worlds research and related fields study a set of network structures with well-defined properties. This new area has been gaining momentum lately. Theoretical studies have advanced our understanding of such networks while empirical studies have shown these networks to be ubiquitous in both nature and society. In particular, systems that appear to be well modeled by such networks include World Wide Web documents, Internet routers, the cellular metabolic network, ecological food webs, social networks, and many others. The two main structures being investigated are small-world networks and scale-free networks. Three recent books, including two just published this summer, describe the research being undertaken in this burgeoning field. We survey and review these books through a discussion of the field of small-worlds research with numerous examples and considerations of the future of the field. © 2003 Wiley Periodicals, Inc. [source] Combustion synthesis and characterization of nano-crystalline LaFeO3 powderPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 7 2009Hui Shen Abstract Nano-crystalline LaFeO3 was synthesized by a sol,gel auto-combustion method from a mixed aqueous solution of lanthanum and iron nitride, using citric acid as the fuel. Powder X-ray diffraction and TG/DTA analysis show that the LaFeO3 crystallites can be directly obtained by the sol,gel combustion process, without any other undesired phase. The results of SEM and TEM reveal that the as-burnt samples and powder calcined at 700 °C are agglomerated with particle size in the range of 25,50 nm and 60,80 nm, respecitvely. The M (T) and M (H) curves measurements show the existence of a weak ferromagnetism and the mainly anti-ferromagnetic ordering of the spins in the calcined sample. Compared with the powder calcined at 600 °C and 700 °C, the as-burnt LaFeO3 exhibits much stronger ferromagnetic behavior, with larger magnetization and smaller coercive field. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Magnetic properties of screen-printed (Y0.5Sm0.5)Co5 magnet arraysPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2007D. Bueno-Baques Abstract (Y0.5Sm0.5)Co5 magnet arrays of square ,dots of 300 ,m were prepared by screen printing. A well controlled paste like ink prepared with the (Y0.5Sm0.5)Co5 nanoparticles and a mixture of organic solvent and polymer was used to print different pattern arrays. (Y0.5Sm0.5)Co5 nanoparticles were obtained by mechanical milling starting from arc melted ingots and heat treated in Ar atmosphere. Two different heat treatment were considered, resulting in powders with different magnetic properties. The microstructure of the magnet arrays was studied by scanning electron microscopy (SEM). An isotropic homogeneous distribution of the nanoparticles inside the ,dots was observed. The final shape of the ,dots in the array was found to be highly dependent on the squeeze pressure and speed over the mesh. Magnetic properties were studied by pulsed field magnetometry and vibrating sample magnetometry at room temperature. The micro size arrays showed lower saturation magnetization and a slightly increase in the coercive field. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Photon-assisted tunneling in ac driven double quantum dot spin pumpsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 6 2006R. Sánchez Abstract In this work, we study the effect of an applied ac gate voltage on the spin filtering and pumping properties of a lateral double quantum dot, in the Coulomb blockade and weak coupling regimes, considering not only the effect of the ac potential on the inter-dot tunneling but also on the tunneling through the leads. This last effect accounts for additional photon absorption and emission processes and therefore affects the spin polarization of the pumped current. In particular, we find that the spin down filtering property can be affected depending on the intensity of the ac field. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] | |||||||||||||||||||||||||||||||