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Homogeneous
Kinds of Homogeneous Terms modified by Homogeneous Selected AbstractsPyridine Carboxylate Complexes of MoII as Active Catalysts in Homogeneous and Heterogeneous PolymerizationEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 18 2007Maria Vasconcellos-Dias Abstract New lamellar materials intercalated with molybdenum(II) complexes with potential catalytic properties were prepared by a stepwise procedure. The lamellar material was first calcined at 823 K for four hours to eliminate all the carbonate ions; the layered structure was reconstructed after treatment with a solution of either pycH (pyridine-2-carboxylic acid) or pydcH2 (pyridine-2,6-dicarboxylic acid) in a KOH solution of dmf at 343 K. Impregnation with a solution of the organometallic precursor [Mo(CO)3I2(NCCH3)2] led to substitution of the nitrile groups by two pyridine ligands. All the materials were characterized by powder X-ray diffraction, FTIR, and 13C CP MAS and 27Al MAS solid-state NMR spectroscopy. Similar MoII complexes were also prepared by using pycH or pydcH2 and characterized by elemental analysis as well as FTIR and 1H and 13C solution NMR spectroscopy. These new materials and the complexes of pyc or pydc ligands containing 4.54 wt.-% and 6.33 wt.-% of Mo respectively, catalyze the ring-opening-metathesis polymerization of norbornene and the polymerization of styrene at 333 K, their performance increasing upon the addition of methylalumoxane (MAO) as cocatalyst.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Convergence study of a family of flux-continuous, finite-volume schemes for the general tensor pressure equationINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 9-10 2006Mayur Pal Abstract In this paper, a numerical convergence study of family of flux-continuous schemes is presented. The family of flux-continuous schemes is characterized in terms of quadrature parameterization, where the local position of continuity defines the quadrature point and hence the family. A convergence study is carried out for the discretization in physical space and the effect of a range of quadrature points on convergence is explored. Structured cell-centred and unstructured cell-vertex schemes are considered. Homogeneous and heterogeneous cases are tested, and convergence is established for a number of examples with discontinuous permeability tensor including a velocity field with singularity. Such cases frequently arise in subsurface flow modelling. A convergence comparison with CVFE is also presented. Copyright © 2006 John Wiley & Sons, Ltd. [source] Homogeneous, unimolecular gas-phase elimination kinetics of ethyl esters of glyoxylic, 2-oxo-propanoic, and 3-methyl-2-oxo-butanoic acidsINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 5 2007Andreina Reyes The rates of elimination of several ethyl esters of 2-oxo-carboxylic acid were determined in a seasoned static reaction vessel over the temperature range 350,430°C and pressure range 33,240 Torr. The reactions, in the presence of a free-radical inhibitor, are homogeneous, unimolecular, and follow a first-order rate law. The overall and partial rate coefficients are expressed by the Arrhenius equation. Ethyl glyoxalate Ethyl 2-oxo-propionate Ethyl 3-methyl-2-oxo-butyrate The mechanisms of these elimination reactions are described in terms of concerted cyclic transition state structures. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 268,275, 2007 [source] Cationic Carboxylato Complexes of Dirhodium(II) with Oxo Thioethers: Catalysts for Silane Alcoholysis under Homogeneous and Liquid-Liquid Biphasic ConditionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 16 2007Andrea Biffis Abstract A set of cationic dirhodium(II) complexes with oxo thioethers was prepared and employed as catalysts for the silane alcoholysis reaction. The complexes were found to be highly active under homogeneous conditions, both in the absence and in the presence of a solvent, including coordinating solvents such as N,N -dimethylformamide; the catalysts could be conveniently employed in concentrations as low as 0.01 mol,%, and a maximum TON of 30000 was recorded after 24,h. The same catalysts were also employed under liquid-liquid biphasic conditions with an ionic liquid as the catalyst-containing phase: comparable catalytic activity was observed under these conditions, and the catalyst-containing phase could be recovered and recycled. A chiral cationic dirhodium(II) complex was also prepared in the frame of this work; kinetic resolution of a racemic alcohol was attempted with this catalyst, unfortunately without success. [source] Cover Picture: On the Nature of the Active Species in Palladium Catalyzed Mizoroki,Heck and Suzuki,Miyaura Couplings , Homogeneous or Heterogeneous Catalysis, A Critical Review: (Adv. Synth.ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2006Catal. Abstract The cover picture shows several forms of palladium which have been utilized as precatalysts for Heck and Suzuki coupling reactions. Over the years myriad different precat-alysts have been used and the nature of the true catalytic palladium species has been a subject of intense debate. What is the real catalyst in these reactions? For more details see the review by Nam T.,S. Phan, Matthew Van Der Sluys and Christopher W. Jones on pages,609,679. [source] One-Pot Homogeneous and Heterogeneous Oxidation of Glycerol to Ketomalonic Acid Mediated by TEMPOADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 3 2003Rosaria Ciriminna Abstract Glycerol, an increasingly abundant by-product of biodiesel production, is selectively converted to ketomalonic acid in one pot at pH 10 using NaOCl as regenerating oxidant in water at 2,°C in the presence of catalytic Br, along with the radical TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl). The reaction can also be conducted at completion over a sol-gel silica glass doped with the nitroxyl radical. Considering the stability and versatility of such doped glasses, these materials show real promise as reusable metal-free catalysts for the conversion of a readily available and renewable biofeedstock into a highly valued compound. [source] Aggressive periodontitis is likely influenced by a few small effect genesJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 6 2009Flavia M. De Carvalho Abstract Aim: To evaluate the inheritance mode of aggressive periodontitis in a collection of families with a similar geographic origin. Materials and Methods: Segregation analysis was performed in pedigree data from 74 families by the use of the SEGREG program of SAGE v.5.4.2. Homogeneous no transmission, homogeneous Mendelian transmission, homogeneous general transmission, semi-general transmission and heterogeneous general transmission models were tested assuming the prevalence of aggressive periodontitis as 1% and no deviations from Hardy,Weinberg equilibrium. The parameters of the model were estimated by the method of maximum likelihood, which provides the overall ln (likelihood), -2ln and the AIC (Akaike's score) for each model. The likelihood ratio test (LRT) was used to compare each model against a fully general model (p>0.05). Results: The most parsimonious mode of inheritance was the semi-general transmission model that allows the heterozygote transmission probability to vary. Conclusion: This result provides strong support for the hypothesis that genetic factors play a role in aggressive periodontitis and that a few loci, each with relatively small effects, contribute to aggressive periodontitis, with or without interaction with environmental factors. [source] Effect of density homogeneity on the dynamic response of powder bedsAICHE JOURNAL, Issue 8 2003T. Yanagida Homogeneous and inhomogeneous powder beds subjected to low-magnitude vibration are compared in terms of the dynamic response. The inhomogeneous samples were segregated into two phases: loose and dense phases, layering the two phases horizontally or vertically. An apparent mass, defined as a ratio of the base force to base acceleration, was measured. Comparison of homogeneous and segregated data demonstrated a significant density gradient dependence on the apparent mass data. First, homogeneous systems showed a resonant peak, which gave the longitudinal elastic modulus of the bed via the velocity of longitudinal stress wave propagation. Second, vertically segregated systems exhibited two significant peaks at low frequencies, corresponding to the resonance of each phase. In addition, the apparent mass values at the two peaks were related to the quantity of each phase. Third, horizontally segregated systems exhibited a resonant peak, whose frequency was approximately equal to homogeneous data, but the apparent mass value at the peak differed from homogeneous data. A model based on the fourth-power scaling law, two-phase theory and Rayleigh's energy method gave an interpretation for the insensitivity of the peak frequency to the density gradient in the vertical direction. [source] With Friends Like These: Endogenous Labor Market Segregation with Homogeneous, Nonprejudiced AgentsAMERICAN JOURNAL OF ECONOMICS AND SOCIOLOGY, Issue 3 2009Article first published online: 3 JUN 200, Tavis Barr In the economics literature, labor market segregation is typically assumed to arise either from prejudice (Becker 1971) or from group differences in human capital accumulation (Benabou 1993; Durlauf 2006; Fryer 2006). Many sociological studies, by contrast, consider social network structure as an embodiment of various forms of social capital, including the creation of obligations, information channels, and enforceable trust (Coleman 1988; Portes and Sensenbrenner 1993). When firms hire by referral, social network segregation can lead to labor market segregation (Tilly 1998). Various social network structures may arise from the actions of self-interested individuals (Watts and Strogatz 1998; Jackson 2006); by incorporating concepts of social capital into an economic framework of profit-maximizing firms, this article develops a model of labor markets in which segregation arises endogenously even though agents are homogeneous and have no dislike for each other. Firms hire through referrals, and can enforce discipline by bribing a referrer to prevent a hiree from getting any outside job offers from other friends if he or she shirks. This is possible only if social networks are reasonably closed, so that the referee knows a majority of his or her friends' friends. By segregating into small communities, workers can more effectively create closed social networks. Social networks with different reservation wages will receive different wages; firms can induce such segregation and wage discrimination in the interest of profit. Workers may not benefit from such segregation, except as a best response to being in a society where it already exists; the "friends" in these social networks act as a worker discipline device, and in this way treat each other inimically. [source] Homogeneous and inhomogeneous linewidth broadening of single polar GaN/AlN quantum dotsPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue S2 2009F. Demangeot Abstract We report on the dependence on temperature of the homogeneous and inhomogeneous broadening of the fundamental transition of single polar GaN/AlN quantum dots (QDs). Stranski-Krastanov QDs have been grown by molecular beam epitaxy using NH3 as a nitrogen source, with a very low surface density. Low temperature (LT) microphotoluminescence measurements have been performed on 200 nm wide mesas in order to isolate the luminescence of single QDs. The linewidth is found to vary from 590 ,eV at 4 K up to 1350 ,eV at 65 K in a dot of 6 monolayer height. Though the LT linewidth is still dominated by spectral diffusion, the temperature dependent broadening up to 50 K is mainly accounted for by interactions between excitons and acoustic phonons through a coupling coefficient value nearly two orders of magnitude larger than its counterpart in InAs QDs. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Celebration, USA: The First Sign of What Will Be America's Homogeneous LandscapeTHE JOURNAL OF AMERICAN CULTURE, Issue 2 2007Matt Thomas First page of article [source] Adaptation of the Fungal Parasite Zygorhizidium planktonicum During 200 Generations of Growth on Homogeneous and Heterogeneous Populations of Its Host, the Diatom Asterionella formosa,THE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 2 2008ARNOUT DE BRUIN ABSTRACT. We followed adaptation of the chytrid parasite Zygorhizidium planktonicum during 200 generations of growth on its host, the freshwater diatom Asterionella formosa, in a serial passage experiment. Evolution of parasite fitness was assessed both on a homogenous and heterogeneous host population, consisting of respectively a single new and ten different new host strains. These 10 host strains were genetically different and also varied in their initial susceptibility to the parasite. Parasite fitness increased significantly and rapidly on the new, genetically homogenous host population, but remained unaltered during 200 generations of growth on the heterogeneous host population. Enhanced parasite fitness was the result of faster and more efficient transmission, resulting in higher values of R0 (number of secondary infections). Consequently, parasites that evolved within the uniclonal host population infected significantly more of these hosts than did their ancestors. We thus provide experimental evidence for the widely held view that host genetic diversity restricts evolution of parasites and moderates their harmful effects. Genetically uniform host populations are not only at increased risk from fungal epidemics because they all share the same susceptibility, but also because new parasite strains are able to adapt quickly to new host environments and to improve their fitness. [source] Orthogonal Enantioselectivity Approaches Using Homogeneous and Heterogeneous Catalyst Systems: Friedel,Crafts Alkylation of Indole,ANGEWANDTE CHEMIE, Issue 26 2010Young Kim Dr. Mit Träger oder ohne? Komplementäre homogene und heterogene Katalysatorsysteme für die asymmetrische Friedel-Crafts-Alkylierung von Indolen mit Nitroalkenen wurden entwickelt. Je nach Reaktionsbedingungen (d.,h. mit oder ohne Zugabe eines festen Trägers; siehe Schema) war so jedes der beiden enantiomeren Produkte 2 selektiv zugänglich. [source] The Mechanism of Water Oxidation: From Electrolysis via Homogeneous to Biological CatalysisCHEMCATCHEM, Issue 7 2010Holger Dau Prof. Abstract Striving for new solar fuels, the water oxidation reaction currently is considered to be a bottleneck, hampering progress in the development of applicable technologies for the conversion of light into storable fuels. This review compares and unifies viewpoints on water oxidation from various fields of catalysis research. The first part deals with the thermodynamic efficiency and mechanisms of electrochemical water splitting by metal oxides on electrode surfaces, explaining the recent concept of the potential-determining step. Subsequently, novel cobalt oxide-based catalysts for heterogeneous (electro)catalysis are discussed. These may share structural and functional properties with surface oxides, multinuclear molecular catalysts and the catalytic manganese,calcium complex of photosynthetic water oxidation. Recent developments in homogeneous water-oxidation catalysis are outlined with a focus on the discovery of mononuclear ruthenium (and non-ruthenium) complexes that efficiently mediate O2 evolution from water. Water oxidation in photosynthesis is the subject of a concise presentation of structure and function of the natural paragon,the manganese,calcium complex in photosystem,II,for which ideas concerning redox-potential leveling, proton removal, and OO bond formation mechanisms are discussed. The last part highlights common themes and unifying concepts. [source] A Single Catalyst for Sequential Reactions: Dual Homogeneous and Heterogeneous Behavior of Palladium Nanoparticles in SolutionCHEMCATCHEM, Issue 2 2009Susanna Jansat Dr. One becomes two: Palladium nanoparticles stabilized by ionic liquids are used as the sole catalytic precursors for sequential Heck and hydrogenation processes. The dual role of these systems, which act as both a heterogeneous catalyst and also as a reservoir of catalytically active molecular species, is investigated. [source] ChemInform Abstract: Homogeneous, Anaerobic (N-Heterocyclic Carbene),Pd or ,Ni Catalyzed Oxidation of Secondary Alcohols at Mild Temperatures.CHEMINFORM, Issue 4 2010Christophe Berini Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] ChemInform Abstract: A Homogeneous, Recyclable Rhodium(I) Catalyst for the Hydroarylation of Michael Acceptors.CHEMINFORM, Issue 26 2009Ranjan Jana Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Towards a Facile Synthesis of Triarylethanones: Palladium-Catalyzed Arylation of Ketone Enolates under Homogeneous and Heterogeneous Conditions.CHEMINFORM, Issue 28 2004Fatima Churruca Abstract For Abstract see ChemInform Abstract in Full Text. [source] Cu and Au Metal,Organic Frameworks Bridge the Gap between Homogeneous and Heterogeneous Catalysts for Alkene Cyclopropanation ReactionsCHEMISTRY - A EUROPEAN JOURNAL, Issue 32 2010Avelino Corma Prof. Abstract The copper and gold metal,organic frameworks (MOFs) [Cu3(BTC)2(H2O)3]n, [Cu3(BTC)2] (BTC=benzene-1,3,5-tricarboxylate), and IRMOF-3-SI-Au are active and reusable solid catalysts for the cyclopropanation of alkenes with high chemo- and diastereoselectivities. This type of material gives better results than previous solid catalysts while working together with the homogeneous catalysts. These MOFs can help to bridge the gap between homogeneous and heterogeneous catalysis. [source] Homogeneous [RuIII(Me3tacn)Cl3]-Catalyzed Alkene cis -Dihydroxylation with Aqueous Hydrogen PeroxideCHEMISTRY - AN ASIAN JOURNAL, Issue 1 2008Wing-Ping Yip Dr. Abstract A simple and green method that uses [Ru(Me3tacn)Cl3] (1; Me3tacn=N,N,,N,,-trimethyl-1,4,7-triazacyclononane) as catalyst, aqueous H2O2 as the terminal oxidant, and Al2O3 and NaCl as additives is effective in the cis -dihydroxylation of alkenes in aqueous tert -butanol. Unfunctionalized alkenes, including cycloalkenes, aliphatic alkenes, and styrenes (14 examples) were selectively oxidized to their corresponding cis -diols in good to excellent yield (70,96,%) based on substrate conversions of up to 100,%. The preparation of cis -1,2-cycloheptanediol (119,g, 91,% yield) and cis -1,2-cyclooctanediol (128,g, 92,% yield) from cycloheptene and cyclooctene, respectively, on the 1-mol scale can be achieved by scaling up the reaction without modification. Results from Hammett correlation studies on the competitive oxidation of para -substituted styrenes (,=,0.97, R=0.988) and the detection of the cycloadduct [(Me3tacn)ClRuHO2(C8H14)]+ by ESI-MS for the 1 -catalyzed oxidation of cyclooctene to cis -1,2-cyclooctanediol are similar to those of the stoichiometric oxidation of alkenes by cis -[(Me3tacn)(CF3CO2)RuVIO2]+ through [3+2] cycloaddition (W.-P. Yip, W.-Y. Yu, N. Zhu, C.-M. Che, J. Am. Chem. Soc.2005, 127, 14239). [source] Setting up 13C CP/MAS experimentsCONCEPTS IN MAGNETIC RESONANCE, Issue 1 2004R.E. Taylor Abstract The 13C cross-polarization (CP) technique combined with magic angle spinning (MAS) has become one of the more commonly performed solid-state nuclear magnetic resonance (NMR) experiments. The basics of initially setting up the experiment are given and used to illustrate such NMR phenomena as rotational echoes, homogeneous and inhomogeneous interactions, continuous wave 1H decoupling, and coupling of quadrupolar 14N nuclei to 13C nuclei. The polarization transfer from the protons to the carbons is described briefly with the usual thermodynamic and quantum mechanical models. The setup and use of the experiment for routine analyses are discussed. © 2004 Wiley Periodicals, Inc. Concepts Magn Reson 22A: 37,49, 2004. [source] Simple NMR-mouse with a bar magnet,CONCEPTS IN MAGNETIC RESONANCE, Issue 4 2002B. Blümich Abstract A new concept of the NMR Mobile Universal Surface Explorer (NMR-MOUSE) using simple bar magnets instead of u-shaped magnets is described. The magnetic field profiles are comparatively homogeneous in extended lateral planes, and close to the magnet pole face the axial gradient is nearly constant. Different geometric arrangements of figure-8 coils adapted to the sample geometry are described. Simulations and measurements of the magnetic field from the magnets and the radio frequency coils are discussed. © 2002 Wiley Periodicals, Inc. Concepts in Magnetic Resonance (Magn Reson Engineering) 15: 255,261, 2002 [source] Mediation and feminism: Common values and challengesCONFLICT RESOLUTION QUARTERLY, Issue 1 2000Marsha Lichtenstein Mediation, and transformative mediation in particular, share several values, despite feminist criticisms of mediation. This article discusses three of the elements that mediation and feminism share. Both promote self-determination, both encourage strengthening values such as empathy and caring in the public sphere, and both deal with the issue of power and have attempted to redefine power to include behaviors other than dominance. Because feminism has gone through the growing pains of shifting from a homogeneous and middle-class movement to a colorful pluralistic social movement, it may serve as a model for the mediation movement as it expands and faces the demands of a demo-graphically diverse constituency. [source] The regulation of muscle glycogen: the granule and its proteinsACTA PHYSIOLOGICA, Issue 4 2010T. E. Graham Abstract Despite decades of studying muscle glycogen in many metabolic situations, surprisingly little is known regarding its regulation. Glycogen is a dynamic and vital metabolic fuel that has very limited energetic capacity. Thus its regulation is highly complex and multifaceted. The stores in muscle are not homogeneous and there appear to be various metabolic pools. Each granule is capable of independent regulation and fundamental aspects of the regulation appear to be associated with a complex set of proteins (some are enzymes and others serve scaffolding roles) that associate both with the granule and with each other in a dynamic fashion. The regulation includes altered phosphorylation status and often translocation as well. The understanding of the roles and the regulation of glycogenin, protein phosphatase 1, glycogen targeting proteins, laforin and malin are in their infancy. These various processes appear to be the mechanisms that give the glycogen granule precise, yet dynamic regulation. [source] Longitudinal Dust Lattice Shock Wave in a Strongly Coupled Complex Dusty PlasmaCONTRIBUTIONS TO PLASMA PHYSICS, Issue 8 2008S. Ghosh Abstract The effect of hydrodynamical damping that arises due to the irreversible processes within the system have been studied on 1D nonlinear longitudinal dust lattice wave (LDLW) in homogeneous strongly coupled complex (dusty) plasma. Analytical investigation shows that the nonlinear wave is governed by Korteweg-de Vries Burgers' equation. This hydrodynamical damping induced dissipative effect is responsible for the Burgers' term that causes the generation of shock wave in dusty plasma crystal. Numerical investigation on the basis of the glow-discharge plasma parameters reveal that LDLW exhibits both oscillatory and monotonic shock. The shock is compressive in nature and its strength decreases (increases) with the increase of the shielding parameter , (characteristic length L). The effects of dust-neutral collision are also discussed. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Nanocrystalline non-planar carbons: Growth of carbon nanotubes and curled nanostructuresCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10-11 2005S. Orlanducci Abstract We present a variety of non-planar graphitic nanostructures selectively generated in a modified Hot-Filament Chemical Vapour Deposition (HF-CVD) apparatus, using purpose-synthesized amorphous carbon nanoparticles or graphite powders as solid state precursor. The employed methodologies enable to successfully synthesize homogeneous and well organized deposits of single- and multi-walled carbon nanotubes, onion-like nanostructures, and nanotube bundles coated by nano-sized diamond grains. Variations in the morphological aspect of such non-planar graphite-based nanostructures are observed changing the experimental conditions: the solid state reactants, the filament and substrate temperatures, the catalyst concentration, and the atomic hydrogen flux over the substrate play key roles in the phenomenon. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Learning from Difference: Considerations for Schools as CommunitiesCURRICULUM INQUIRY, Issue 3 2000Carolyn M. Shields In today's highly complex and heterogeneous public schools, the current notion of schools as homogeneous communities with shared beliefs, norms, and alues is inadequate. Drawing on Barth's (1990) question of how to use ifference as a resource, I take up ideas from feminism, multiculturalism, and inclusive education to consider the development of community in schools. I argue that despite the valuable contributions of these theoretical perspectives, each lso includes the potential for increased fragmentation and polarization. As we consider how to use differences as a foundation for community, it is important ot to reify any particular perspective, thus marginalizing others and erecting new barriers. Explicitly embracing the need to identify and respect difference, being open to new ideas without taking an exclusionary position, and committing to ongoing participation in dialogical processes may help schools to develop as more authentic communities of difference. Among the dominant issues identified in today's climate of turbulent educational reform are concerns about how to restructure schools to ensure equality of student opportunity and excellence of instruction (Elmore, 1990; Lieberman, 1992; Murphy, 1991). Many proposals include modifying present leadership and governance structures, overcoming the hegemony of existing power bases, developing mechanisms for accountability, enhancing professionalism, and co-ordinating community resources. One of the suggestions frequently made to address these issues is to change from a focus on schools as organizations to a recognition of schools as communities (Barth, 1990; Fullan, 1993; Lupart & Webber, 1996; Senge, 1990). However, despite the widespread use of the metaphor of community as an alternative to the generally accepted concept of schools as rational or functional organizations, there seems to be little clarity about the concept of community, what it might look like, how it might be implemented, or what policies might sustain it. Indeed, theories about schools as communities have often drawn from Tönnies (1887/1971) concept of gemeinschaft,a concept which perhaps evokes a more homogeneous and romanticized view of the past than one which could be helpful for improving education in today's dynamic, complex, and heterogeneous context (Beck & Kratzer, 1994; Sergiovanni, 1994a). More recently, several writers (Fine et al., 1997; Furman, 1998; Shields & Seltzer, 1997) have advanced the notion of communities of otherness or difference. These authors have suggested that rather than thinking of schools as communities that exist because of a common affiliation to an established school ethos or tradition, it might be more helpful to explore an alternative concept. A school community founded on difference would be one in which the common centre would not be taken as a given but would be co-constructed from the negotiation of disparate beliefs and values as participants learn to respect, and to listen to, each other. In this concept, bonds among members are not assumed, but forged, and boundaries are not imposed but negotiated. Over the past eight years, as I have visited and worked with a large number of schools trying earnestly to address the needs of their diverse student bodies, I have become increasingly aware of the limitations of the concept of community used in the gemeinschaft sense with its emphasis on shared values, norms, and beliefs, and have begun to reflect on the question framed by Barth (1990): ,How can we make conscious, deliberate use of differences in social class, gender, age, ability, race, and interest as resources for learning?' (p. 514). In this article, I consider how learning from three of these areas of difference: gender, race, and ability, may help us to a better understanding of educational community. This article begins with some illustrations and examples from practice, moves to consider how some theoretical perspectives may illuminate them, and concludes with reflections on how the implications of the combined reflections on practice and theory might actually help to reconceptualize and to improve practice. While it draws heavily on questions and impressions which have arisen out of much of my fieldwork, it is not intended to be an empirical paper, but a conceptual one,one which promotes reflection and discussion on the concept of schools as communities of difference. The examples of life in schools taken from longitudinal research studies in which I have been involved demonstrate several common ways in which difference is dealt with in today's schools and some of the problems inherent in these approaches. Some ideas drawn from alternative perspectives then begin to address Barth's question of how to make deliberate use of diversity as a way of thinking about community. Taken together, I hope that these ideas will be helpful in creating what I have elsewhere called ,schools as communities of difference' (Shields & Seltzer, 1997). [source] Acculturation is associated with the prevalence of tardive dyskinesia and akathisia in community-treated patients with schizophreniaACTA PSYCHIATRICA SCANDINAVICA, Issue 6 2008S. Sundram Objective:, Ethnicity is a risk factor for tardive dyskinesia (TD) and other antipsychotic drug-induced movement disorders (ADIMD). It is unclear whether this association is mediated through genetic, environmental or cultural factors individually or in combination. This pilot study aimed to explore this interaction by determining if acculturation in migrant groups contributed to the prevalence of ADIMD. Method:, Culturally diverse but relatively genetically homogeneous (white Caucasian) patients with schizophrenia (n = 40) treated at a single site were assessed for the presence of ADIMD and level of acculturation. Results:, Higher levels of acculturation correlated with an increased prevalence of TD and akathisia but not Parkinsonism. The level of acculturation significantly predicted TD. Conclusion:, This study identifies for the first time that acculturation significantly contributes to the prevalence of TD and akathisia but not Parkinsonism in culturally diverse migrant populations and must be accounted for when explaining ethnic variation in rates of ADIMD. [source] Mental Causation and Mental PropertiesDIALECTICA, Issue 1 2005Michael Esfeld The aim of this paper is to defend the causal homogeneity of functional, mental properties against Kim's attack. It is argued that (a) token identity is sufficient for mental causation, that (b) token identity implies a sort of functional reduction, but that (c) nonetheless functional, mental properties can be causally homogeneous despite being multiply realizable: multiple composition is sufficient for multiple realizability, but multiple composition does not prevent the realizers from having their pertinent effects in common. Thus, the causal exclusion problem provides no argument for abandoning the position that there are functional, mental properties that are natural kind properties. [source] Alcohol and injuries: a review of international emergency room studies since 1995DRUG AND ALCOHOL REVIEW, Issue 2 2007CHERYL J. CHERPITEL Abstract This paper provides a review of emergency room (ER) studies on alcohol and injury, using representative probability samples of adult injury patients, and focuses on the scope and burden of the problem as measured by estimated blood alcohol concentration (BAC) at the time of the ER visit, self-report drinking prior to injury, violence-related injury and alcohol use disorders. A computerized search of the English-language literature on MEDLINE, PsychINFO and the National Institute on Alcohol Abuse and Alcoholism (NIAAA) Alcohol and Alcohol Problems Science Database (ETOH) was conducted for articles published between 1995 and 2005, using the following key descriptors: (1) emergency room/emergency department/accident and emergency, (2) alcohol/drinking and (3) injuries (intentional and unintentional). Findings support prior reviews, with injured patients more likely to be positive for BAC and report drinking prior to injury than non-injured, and with the magnitude of the association substantially increased for violence-related injuries compared to non-violence-related injuries. Indicators of alcohol use disorders did not show a strong association with injury. Findings were not homogeneous across studies, however, and contextual variables, including study-level detrimental drinking pattern, explained some of the variation. This review represents a broader range of ER studies than that reported previously, across both developed and developing countries, and has added to our knowledge base in relation to the influence of contextual variables on the alcohol-injury relationship. Future research on alcohol and injury should focus on obtaining representative samples of ER patients, with special attention to both acute and chronic alcohol use, and to organisational and socio-cultural variables that may influence findings across studies. In-depth patient interviews may also be useful for a better understanding of drinking in the injury event and associated circumstances. [source] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||