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Selected AbstractsImproved understanding of velocity,saturation relationships using 4D computer-tomography acoustic measurementsGEOPHYSICAL PROSPECTING, Issue 2 2005K. Monsen ABSTRACT A recently developed laboratory method allows for simultaneous imaging of fluid distribution and measurements of acoustic-wave velocities during flooding experiments. Using a specially developed acoustic sample holder that combines high pressure capacity with good transparency for X-rays, it becomes possible to investigate relationships between velocity and fluid saturation at reservoir stress levels. High-resolution 3D images can be constructed from thin slices of cross-sectional computer-tomography scans (CT scans) covering the entire rock-core volume, and from imaging the distribution of fluid at different saturation levels. The X-ray imaging clearly adds a new dimension to rock-physics measurements; it can be used in the explanation of variations in measured velocities from core-scale heterogeneities. Computer tomography gives a detailed visualization of density regimes in reservoir rocks within a core. This allows an examination of the interior of core samples, revealing inhomogeneities, porosity and fluid distribution. This mapping will not only lead to an explanation of acoustic-velocity measurements; it may also contribute to an increased understanding of the fluid-flow process and gas/liquid mixing mechanisms in rock. Immiscible and miscible flow in core plugs can be mapped simultaneously with acoustic measurements. The effects of core heterogeneity and experimentally introduced effects can be separated, to clarify the validity of measured velocity relationships. [source] Delay aware reliable transport in wireless sensor networksINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 10 2007Vehbi C. Gungor Abstract Wireless sensor networks (WSN) are event-based systems that rely on the collective effort of several sensor nodes. Reliable event detection at the sink is based on collective information provided by the sensor nodes and not on any individual sensor data. Hence, conventional end-to-end reliability definitions and solutions are inapplicable in the WSN regime and would only lead to a waste of scarce sensor resources. Moreover, the reliability objective of WSN must be achieved within a certain real-time delay bound posed by the application. Therefore, the WSN paradigm necessitates a collective delay-constrained event-to-sink reliability notion rather than the traditional end-to-end reliability approaches. To the best of our knowledge, there is no transport protocol solution which addresses both reliability and real-time delay bound requirements of WSN simultaneously. In this paper, the delay aware reliable transport (DART) protocol is presented for WSN. The objective of the DART protocol is to timely and reliably transport event features from the sensor field to the sink with minimum energy consumption. In this regard, the DART protocol simultaneously addresses congestion control and timely event transport reliability objectives in WSN. In addition to its efficient congestion detection and control algorithms, it incorporates the time critical event first (TCEF) scheduling mechanism to meet the application-specific delay bounds at the sink node. Importantly, the algorithms of the DART protocol mainly run on resource rich sink node, with minimal functionality required at resource constrained sensor nodes. Furthermore, the DART protocol can accommodate multiple concurrent event occurrences in a wireless sensor field. Performance evaluation via simulation experiments show that the DART protocol achieves high performance in terms of real-time communication requirements, reliable event detection and energy consumption in WSN. Copyright © 2007 John Wiley & Sons, Ltd. [source] A regional impact assessment of climate and land-use change on alpine vegetationJOURNAL OF BIOGEOGRAPHY, Issue 3 2003Thomas Dirnböck Abstract Aim, Assessing potential response of alpine plant species distribution to different future climatic and land-use scenarios. Location, Four mountain ranges totalling 150 km2 in the north-eastern Calcareous Alps of Austria. Methods, Ordinal regression models of eighty-five alpine plant species based on environmental constraints and land use determining their abundance. Site conditions are simulated spatially using a GIS, a Digital Terrain Model, meteorological station data and existing maps. Additionally, historical records were investigated to derive data on time spans since pastures were abandoned. This was then used to assess land-use impacts on vegetation patterns in combination with climatic changes. Results, A regionalized GCM scenario for 2050 (+ 0.65 °C, ,30 mm August precipitation) will only lead to local loss of potential habitat for alpine plant species. More profound changes (+ 2 °C, ,30 mm August precipitation; + 2 °C, ,60 mm August precipitation) however, will bring about a severe contraction of the alpine, non-forest zone, because of range expansion of the treeline conifer Pinus mugo Turra and many alpine species will loose major parts of their habitat. Precipitation change significantly influences predicted future habitat patterns, mostly by enhancing the general trend. Maintenance of summer pastures facilitates the persistence of alpine plant species by providing refuges, but existing pastures are too small in the area to effectively prevent the regional extinction risk of alpine plant species. Main conclusions, The results support earlier hypotheses that alpine plant species on mountain ranges with restricted habitat availability above the treeline will experience severe fragmentation and habitat loss, but only if the mean annual temperature increases by 2 °C or more. Even in temperate alpine regions it is important to consider precipitation in addition to temperature when climate impacts are to be assessed. The maintenance of large summer farms may contribute to preventing the expected loss of non-forest habitats for alpine plant species. Conceptual and technical shortcomings of static equilibrium modelling limit the mechanistic understanding of the processes involved. [source] All in the family: Using inherited cancer syndromes to understand de-regulated cell signaling in brain tumorsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 4 2007S. Sean Houshmandi Abstract The cell signaling pathways that are tightly regulated during development are often co-opted by cancer cells to allow them to escape from the constraints that normally limit cell growth and cell movement. In this regard, de-regulated signaling in cancer cells confers a number of key tumor-associated properties, including increased cell proliferation, decreased cell death, and increased cell motility. The identification of some of these critical signaling pathways in the nervous system has come from studies of inherited cancer syndromes in which affected individuals develop brain tumors. The study of brain tumors arising in patients with neurofibromatosis 1 (NF1), neurofibromatosis 2 (NF2), and tuberous sclerosis complex (TSC) has already uncovered several key intracellular signaling pathways important for modulating brain tumor growth. An in-depth analysis of these intracellular signaling pathways will not only lead to an improved understanding of the process of brain tumorigenesis, but may also provide important molecular targets for future therapeutic drug design. J. Cell. Biochem. 102: 811,819, 2007. © 2007 Wiley-Liss, Inc. [source] Isofurans, but not F2 -isoprostanes, are increased in the substantia nigra of patients with Parkinson's disease and with dementia with Lewy body diseaseJOURNAL OF NEUROCHEMISTRY, Issue 3 2003Joshua P. Fessel Abstract F2 -isoprostanes (F2 -IsoPs) are well-established sensitive and specific markers of oxidative stress in vivo. Isofurans (IsoFs) are also products of lipid peroxidation, but in contrast to F2 -IsoPs, their formation is favored when oxygen tension is increased in vitro or in vivo. Mitochondrial dysfunction in Parkinson's disease (PD) may not only lead to oxidative damage to brain tissue but also potentially result in increased intracellular oxygen tension, thereby influencing relative concentrations of F2 -IsoPs and IsoFs. In this study, we attempted to compare the levels of F2 -IsoPs and IsoFs esterified in phospholipids in the substantia nigra (SN) from patients with PD to those of age-matched controls as well as patients with other neurodegenerative diseases, including dementia with Lewy body disease (DLB), multiple system atrophy (MSA), and Alzheimer's disease (AD). The results demonstrated that IsoFs but not F2 -IsoPs in the SN of patients with PD and DLB were significantly higher than those of controls. Levels of IsoFs and F2 -IsoPs in the SN of patients with MSA and AD were indistinguishable from those of age-matched controls. This preferential increase in IsoFs in the SN of patients with PD or DLB not only indicates a unique mode of oxidant injury in these two diseases but also suggests different underlying mechanisms of dopaminergic neurodegeneration in PD and DLB from those of MSA. [source] Influence of the supporting salt concentration on the electrodeposition of ZnO/eosin Y hybrid filmsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 10 2008C. Boeckler Abstract ZnO/eosin Y hybrid films were electrodeposited from O2 -saturated ZnCl2 -solution under variation of the concentration of the supporting salt KCl. The supporting salt concentration was found to have a significant influence on the amount of dye loading and the morphology of the ZnO/eosin Y films. By decreasing the supporting salt concentration to 0.01 M KCl, porous films with a high dye loading can be obtained at potentials of ,0.8 V vs. SCE at low eosin Y concentrations in the electrodeposition bath, which usually only lead to porous films at potentials where eosin Y is reduced (< ,0.9 V vs. SCE). (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Increased blood loss in upright birthing positions originates from perineal damageBJOG : AN INTERNATIONAL JOURNAL OF OBSTETRICS & GYNAECOLOGY, Issue 3 2007A De Jonge Objective, To assess whether the risk of severe blood loss is increased in semi-sitting and sitting position, and if so, to which extent blood loss from perineal damage is responsible for this finding. Design, Secondary analysis of data from a large trial. Setting, Primary care midwifery practices in the Netherlands. Population, About 1646 low-risk women who had a spontaneous vaginal delivery. Methods, Blood loss was measured using a weighing scale and measuring jug. Logistic regression analysis was used to examine the net effects of birthing position and perineal damage on blood loss greater than 500 ml. Main outcome measures, Mean total blood loss and incidence of blood loss greater than 500 ml and 1000 ml. Results, Mean total blood loss and the incidence of blood loss greater than 500 ml and 1000 ml were increased in semi-sitting and sitting position. In logistic regression analysis, the interaction between birthing position and perineal damage was almost significantly associated with an increased risk of blood loss greater than 500 ml. Semi-sitting and sitting position were only significant risk factors among women with perineal damage (OR 1.30, 95% CI 1.00,1.69 and OR 2.25, 95% CI 1.37,3.71, respectively). Among women with intact perineum, no association was found. Conclusions, Semi-sitting and sitting birthing positions only lead to increased blood loss among women with perineal damage. [source] Inclusion Behavior of ,-Cyclodextrin with Bipyridine Molecules: Factors Governing Host-Guest Inclusion GeometriesCHEMISTRY - AN ASIAN JOURNAL, Issue 3 2009Yan-Li Zhao Dr. Abstract Guest Effect: The differences of nitrogen atom positions and the bridge bonds linked to two pyridine rings of some bipyridine guests can significantly affect the binding abilities and inclusion geometries of ,-cyclodextrin with the guests in both the solution and solid states. The 1:1 complexation of ,-cyclodextrin (,-CD) with structurally similar bipyridine guests which lead to the formation of six inclusion complexes (1,6) of ,-CD with 4,4,-vinylenedipyridine, 2,2,-vinylenedipyridine, 1-(2-pyridyl)-2-(4-pyridyl)ethylene, 4,4,-ethylene-dipyridine, 4,4,-dithiodipyridine, and 2,2,-dithiodipyridine has been investigated comprehensively by X-ray crystallography in the solid state and by 1H,NMR spectroscopy and microcalorimetric titration in aqueous solution. The complex formation constants (KS) for the stoichiometric 1:1 host,guest inclusion complexation of ,-CD with the bipyridine derivatives were determined in aqueous solution by microcalorimetry and the host,guest inclusion geometries of the complexes were deduced from 1H ROESY NMR spectroscopy. It transpires that the guest bipyridine molecules are included in the ,-CD cavity with a range of different inclusion geometries. In the solid state, the crystal superstructures for the ,-CD complexes 1, 4, and 5 are characterized by the triclinic crystal system (space group P1) commensurate with AAAA type supramolecular aggregation. By contrast, the ,-CD complexes 2, 3, and 6 display either monoclinic (space group P21) or orthorhombic (space group C2221) crystal systems, characteristic of ABAB type supramolecular aggregation. The results demonstrate that the relative locations of the nitrogen atom positions and the bridge-bond links between the two pyridine rings in these bipyridine guests, not only lead to distinct crystal systems and space groups, but also to different binding geometries and thermodynamical parameters on complexation of the bipyridines with ,-CD. The knowledge obtained from this research improves our understanding of the molecular recognition and self-assembly processes exhibited by ,-CD, both in the solid state and in aqueous solution. [source] Revealing the human mutomeCLINICAL GENETICS, Issue 4 2010JM Chen Chen JM, Férec C, Cooper DN. Revealing the human mutome. The number of known mutations in human nuclear genes, underlying or associated with human inherited disease, has now exceeded 100,000 in more than 3700 different genes (Human Gene Mutation Database). However, for a variety of reasons, this figure is likely to represent only a small proportion of the clinically relevant genetic variants that remain to be identified in the human genome (the ,mutome'). With the advent of next-generation sequencing, we are currently witnessing a revolution in medical genetics. In particular, whole-genome sequencing (WGS) has the potential to identify all disease-causing or disease-associated DNA variants in a given individual. Here, we use examples of recent advances in our understanding of mutational/pathogenic mechanisms to guide our thinking about possible locations outwith gene-coding sequences for those disease-causing or disease-associated variants that are likely so often to have been overlooked because of the inadequacy of current mutation screening protocols. Such considerations are important not only for improving mutation-screening strategies but also for enhancing the interpretation of findings derived from genome-wide association studies, whole-exome sequencing and WGS. An improved understanding of the human mutome will not only lead to the development of improved diagnostic testing procedures but should also improve our understanding of human genome biology. [source] Mutations in sarcomeric protein genes not only lead to cardiomyopathy but also to congenital cardiovascular malformationsCLINICAL GENETICS, Issue 1 2008Marja W. Wessels Noncompaction of the ventricular myocardium is associated with de novo mutation in the beta-myosin heavy chain gene Budde et al. (2007) PLoS ONE 2: e1362 Homozygosity for a novel splice site mutation in the cardiac myosin-binding protein C gene causes severe neonatal hypertrophic cardiomyopathy Xin et al. (2007) Am J Med Genet 143: 2662,2667 Alpha-cardiac actin mutations produce atrial septal defects Matsson et al. (2008) Hum Mol Genet 17: 256,265 [source] Diabetes mellitus and geriatric syndromesGERIATRICS & GERONTOLOGY INTERNATIONAL, Issue 2 2009Atsushi Araki Diabetes mellitus is associated with an increased prevalence and incidence of geriatric syndrome: functional disabilities, depression, fall, urinary incontinence, malnutrition and cognitive impairment. Geriatric syndrome not only leads to frailty, loss of independence and low quality of life, but also becomes a major obstacle in the treatment and care of diabetic people. The risk factors or contributing factors of geriatric symptoms are micro- and macrovascular complications, age-rated comorbid disease and aging per se. Comprehensive geriatric assessment of geriatric syndrome, including basic activities of daily living, instrumental activities of daily living, gait and balance, visual acuity, the Mini-Mental State Examination, depression scores, history and risk of fall, urination and nutrition, should be performed as part of the care of elderly diabetic patients, in particular old-old patients. Because geriatric syndromes are multifactorial and share risk factors, diabetic people with any geriatric symptoms should be treated with a common concentric strategy, such as supervised exercise therapy including muscle-strengthening training, psychological support, social support for adherence, and good glycemic control with avoidance of hypoglycemia. [source] Theory of tip-dependent imaging of adsorbates in the STM: CO on Cu(111)INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 6 2006D. Drakova Abstract The processes of local electron injection or extraction in the scanning tunneling microscopy (STM) and spectroscopy (STS) lead to the creation of short-lived excited states localized at the electrode surfaces. The dynamic relaxation of the transient negative or positive ion resonances, due to both local and long-range interactions, is the clue to the understanding of numerous phenomena in STM/STS ranging from the "anomalously" large tip height corrugation amplitudes on clean metal surfaces to the observation of quantum mirages and features in the STS, which are not observed with the help of other surface spectroscopies. Quantum nanodynamics theory (QND) has been applied to calculate the interaction potential of a single CO molecule with the Cu(111) surface, with a transient negative ion resonance formed when an electron is injected from the tip, and the tunneling conductance on the clean and CO covered Cu(111) surface using a clean metal tip Al/Al(111) and a Pt(111) tip with an adsorbed CO molecule at the apex. Within QND and three-dimensional scattering theory, regarding the tunneling as an excited-state problem, we provide the explanation of the tip-dependent STM image of a single CO molecule on Cu(111). The appearance of the CO molecule as an indentation, using a clean metal tip and as a protrusion with a tip terminated by a CO molecule, is understood as a result of tunneling through two competing channels. Tunneling via adsorbate-induced ion resonances enhances the tunneling conductance. In contrast, tunneling via metal ion resonances only leads to attenuation of the conductance in the presence of the adsorbate. The current in the vicinity of the adsorbed CO molecule is reduced when a clean metal tip is used; i.e., CO appears dark in the STM image, because metal ion resonances on Cu(111) derive from the surface states with image state components coupling to plasmons and are therefore very diffuse. With a CO-terminated tip, the major current channel is, for symmetry reasons, from the 2,-derived orbital of the tip CO molecule, via the diffuse 2,-derived orbital of the CO molecule on the sample, hence adsorbed CO appears bright. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source] Paradoxical enhancement of oxidative cell injury by overexpression of heme oxygenase-1 in an anchorage-dependent cell ECV304JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 3 2004Keiko Maruhashi Abstract There has been increasing evidence suggesting the potent anti-inflammatory roles of heme oxygenase-1 (HO-1) in protecting renal tubular epithelial cells, vascular endothelial cells, and circulating monocytes. Based on these findings, novel therapeutic interventions have been proposed to control the expression of endothelial HO-1 levels to ameliorate various vascular diseases. We evaluated the effect of HO-1 gene transfer into an anchorage-dependent cell, ECV304. Effect of HO-1 production on the cell injury induced by hydrogen peroxide was evaluated after hemin stimulation and after HO-1 gene transfection. Morphological changes and the induction of various anti-apoptotic proteins were examined at the same time. Levels of HO-1 expression were variable in different clones of HO-1-transfected ECV304 cells. Among these, the clones with moderate levels of HO-1 expression were significantly more resistant to oxidative stress. In contrast, those with the highest levels of HO-1 exhibited paradoxically enhanced susceptibility to oxidative injury. Interestingly, the cell survival after oxidative stress was in parallel with the levels of Bcl-2 expression and of fibronectin receptor, ,5 integrin. It is suggested from these results, that excessive HO-1 not only leads to enhanced cell injury, but also prolongs the repair process of the injured endothelial tissue. However, HO-1 reduces the oxidative cell injury and protects the endothelial cells, if its expression is appropriately controlled. © 2004 Wiley-Liss, Inc. [source] A POST-KEYNESIAN AMENDMENT TO THE NEW CONSENSUS ON MONETARY POLICYMETROECONOMICA, Issue 2 2006Article first published online: 24 APR 200, Marc Lavoie ABSTRACT A common view is now pervasive in policy research at universities and central banks, which one could call the New Keynesian consensus, based on an endogenous money supply. This new consensus reproduces received wisdom: in the long run, expansionary fiscal policy leads to higher inflation rates and real interest rates, while more restrictive monetary policy only leads to lower inflation rates. The paper provides a simple four-quadrant apparatus to represent the above, and it shows that simple modifications to the new consensus model are enough to radically modify received doctrine as to the likely effects of fiscal and monetary policies. [source] SREA is involved in regulation of siderophore biosynthesis, utilization and uptake in Aspergillus nidulansMOLECULAR MICROBIOLOGY, Issue 5 2001Harald Oberegger Under conditions of low iron availability, most fungi excrete siderophores in order to mobilize extracellular iron. We show that lack of the GATA-type transcription factor SREA in Aspergillus nidulans not only leads to derepression of siderophore biosynthesis but also to deregulation of siderophore-bound iron uptake and ornithine esterase expression. Furthermore, SREA deficiency causes increased accumulation of ferricrocin, the siderophore responsible for intracellular iron storage. In sreA deletion strains, extracellular siderophore production is derepressed but still regulated negatively by iron availability, indicating the presence of an additional iron-regulatory mechanism. In contrast, iron affects ferricrocin accumulation in a positive way, suggesting a protective role for this siderophore in detoxification of intracellular iron excess. The harmfulness of deregulated iron uptake in this mutant is demonstrated by increased expression of genes encoding the antioxidative enzymes catalase CATB and the superoxide dismutases SODA and SODB. It is noteworthy that iron starvation was found to repress catB expression in wild-type (wt) and SREA-deficient strains, consistent with catB being subject to SREA-independent iron regulation. Differential display led to the identification of putative SREA target genes amcA and mirA. The deduced MIRA amino acid sequence displays significant similarity to recently characterized siderophore permeases of Saccharomyces cerevisiae. amcA encodes a putative mitochondrial carrier for the siderophore precursor ornithine, indicating cross-regulation of siderophore and ornithine metabolism. [source] Development of an Acanthamoeba -specific Reverse Dot-Blot and the Discovery of a New RibotypeTHE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 6 2001REBECCA J. CAST ABSTRACT. Acanthamoeba is a genus of free-living amoebae, of which some speeies have been found to cause opportunistic infections in humans. The identification of these amoebae in natural and disease samples is based primarily upon morphological features. While these features are more than adequate for identification to the genus level, they are not useful for species-level identification. This not only leads to difficulty in the diagnosis of infections, but it makes an accurate assessment of the natural distribution of acanthamoebae very difficult to achieve. To improve this situation, a detection method was developed that utilizes both selective polymerase chain reaction amplification and the reverse dot-blot. Oligonucleotides were designed to be specific for the described ribosomal groups (or ribotypes) of Acanthamoeba, as well as one specific for the genus itself. When this method was used to analyze a series of Acanthamoeba cultures from Pakistan, a new ribotype was identified in addition to the detection of the ubiquitously distributed T4 type. [source] CT32 WHEN TO CALL THE SURGEONANZ JOURNAL OF SURGERY, Issue 2007D. P. Shaw Not infrequently, a patient status has changed and the surgeon is not informed. This not only leads to frustration but potentially bad outcomes. Devising a protocol for when to call the surgeon is fraught with difficulties. Frequently they are so complicated that individuals were unable to remember them thus the protocols are not applied. High turnover of junior staff means that large protocol books are not read. The below three rules are designed to fulfil the role of protocols. They are compulsory flags for when the surgeon is to be called. They are not guides to management nor comments on adequacy of management. Their intent is to flag a change in status of the patient. The compulsory nature of the flags reduces the decision making and stress for the resident staff as to whether or not they should be calling the boss. The surgeon is to be called when 1The patient is to receive blood or blood products 2The inotropes dose is doubled from admission 3A vasoconstrictor is started [source] Bayesian source detection and parameter estimation of a plume model based on sensor network measurements,APPLIED STOCHASTIC MODELS IN BUSINESS AND INDUSTRY, Issue 4 2010Chunfeng Huang Abstract We consider a network of sensors that measure the intensities of a complex plume composed of multiple absorption,diffusion source components. We address the problem of estimating the plume parameters, including the spatial and temporal source origins and the parameters of the diffusion model for each source, based on a sequence of sensor measurements. The approach not only leads to multiple-source detection, but also the characterization and prediction of the combined plume in space and time. The parameter estimation is formulated as a Bayesian inference problem, and the solution is obtained using a Markov chain Monte Carlo algorithm. The approach is applied to a simulation study, which shows that an accurate parameter estimation is achievable. Copyright © 2010 John Wiley & Sons, Ltd. [source] Variances Are Not Always Nuisance ParametersBIOMETRICS, Issue 2 2003Raymond J. Carroll Summary In classical problems, e.g., comparing two populations, fitting a regression surface, etc., variability is a nuisance parameter. The term "nuisance parameter" is meant here in both the technical and the practical sense. However, there are many instances where understanding the structure of variability is just as central as understanding the mean structure. The purpose of this article is to review a few of these problems. I focus in particular on two issues: (a) the determination of the validity of an assay; and (b) the issue of the power for detecting health effects from nutrient intakes when the latter are measured by food frequency questionnaires. I will also briefly mention the problems of variance structure in generalized linear mixed models, robust parameter design in quality technology, and the signal in microarrays. In these and other problems, treating variance structure as a nuisance instead of a central part of the modeling effort not only leads to inefficient estimation of means, but also to misleading conclusions. [source] Fe2 and Fe4 Clusters Encapsulated in Vacant Polyoxotungstates: Hydrothermal Synthesis, Magnetic and Electrochemical Properties, and DFT CalculationsCHEMISTRY - A EUROPEAN JOURNAL, Issue 10 2008Céline Pichon Abstract While the reaction of [PW11O39]7, with first row transition-metal ions Mn+ under usual bench conditions only leads to monosubstituted {PW11O39M(H2O)} anions, we have shown that the use of this precursor under hydrothermal conditions allows the isolation of a family of novel polynuclear discrete magnetic polyoxometalates (POMs). The hybrid asymmetric [FeII(bpy)3][PW11O39Fe2III(OH)(bpy)2],12,H2O (bpy=bipyridine) complex (1) contains the dinuclear {Fe(,-O(W))(,-OH)Fe} core in which one iron atom is coordinated to a monovacant POM, while the other is coordinated to two bipyridine ligands. Magnetic measurements indicate that the FeIII centers in complex 1 are weakly antiferromagnetically coupled (J=,11.2,cm,1, H=,JS1S2) compared to other {Fe(,-O)(,-OH)Fe} systems. This is due to the long distances between the iron center embedded in the POM and the oxygen atom of the POM bridging the two magnetic centers, but also, as shown by DFT calculations, to the important mixing of bridging oxygen orbitals with orbitals of the POM tungsten atoms. The complexes [Hdmbpy]2[FeII(dmbpy)3]2[(PW11O39)2Fe4IIIO2(dmbpy)4],14,H2O (2) (dmbpy=5,5,-dimethyl-2,2,-bipyridine) and H2[FeII(dmbpy)3]2[(PW11O39)2Fe4IIIO2(dmbpy)4],10,H2O (3) represent the first butterfly-like POM complexes. In these species, a tetranuclear FeIII complex is sandwiched between two lacunary polyoxotungstates that are pentacoordinated to two FeIII cations, the remaining paramagnetic centers each being coordinated to two dmbpy ligands. The best fit of the ,MT=f(T) curve leads to Jwb=,59.6,cm,1 and Jbb=,10.2,cm,1 (H=,Jwb(S1S2+S1S2*+S1*S2+S1*S2*),Jbb(S2S2*)). While the Jbb value is within the range of related exchange parameters previously reported for non-POM butterfly systems, the Jwb constant is significantly lower. As for complex 1, this can be justified considering FewO distances. Finally, in the absence of a coordinating ligand, the dimeric complex [N(CH3)4]10[(PW11O39FeIII)2O],12,H2O (4) has been isolated. In this complex, the two single oxo-bridged FeIII centers are very strongly antiferromagnetically coupled (J=,211.7,cm,1, H=,JS1S2). The electrochemical behavior of compound 1 both in dimethyl sulfoxide (DMSO) and in the solid state is also presented, while the electrochemical properties of complex 2, which is insoluble in common solvents, have been studied in the solid state. [source] Perspective on Local Governance Reform in ChinaCHINA AND WORLD ECONOMY, Issue 2 2006Mingxing Liu H57; H71; P32; P35 Abstract This paper is an attempt to present an analysis of China's decentralization and local governance practices, the dilemmas rooted in the current institution. We argue that the misbehavior of local government officials is endogenous to China's central-local structure and that competition among localities has become distorted and constrained by various policy burdens and development mandates imposed from above. The information asymmetry for the enforcement cost of mandates that exists between central and local governments not only leads to difficulties and distortions in local performance evaluations, but also creates opportunities for local bureaucracy expansion and rent-seeking. Enhancing fiscal transfers, or strengthening political restraint, although necessary, would be far from enough to solve the local governance problems. The ultimate solution entails an in-depth deregulation reform on factor mobility and a furthest eradication of policy mandates for the local government. Edited by Xinyu Fan [source] | |||||||||||||||||||||||||