bluuebunny/crossref_metadata_2025 huggingface dataset:
Spectral Radiative Heat Transfer Analysis of the Planar SOFC
Authors: Damm David L. , Fedorov Andrei G.
Published: October 2005

Thermo-mechanical failure of components in planar-type solid oxide fuel cells (SOFCs) depends strongly on the local temperature gradients at the interfaces of different materials. Therefore, it is of paramount importance to accurately predict the temperature fields within the stack, especially near the interfaces. Because of elevated operating temperatures (of the order of 1000K or even higher), radiation heat transfer could become a dominant mode of heat transfer in the SOFCs. In this study, we extend our recent work on radiative effects in solid oxide fuel cells [J. Power Sources, 124, No. 2, pp. 453–458] by accounting for the spectral dependence of the radiative properties of the electrolyte material. The measurements of spectral radiative properties of the polycrystalline yttria-stabilized zirconia electrolyte we performed indicate that an optically thin approximation can be used for treatment of radiative heat transfer. To this end, the Schuster–Schwartzchild two-flux approximation is used to solve the radiative transfer equation for the spectral radiative heat flux, which is then integrated over the entire spectrum using an N-band approximation to obtain the total heat flux due to thermal radiation. The divergence of the total radiative heat flux is then incorporated as a heat sink into a three-dimensional thermo-fluid model of a SOFC through the user-defined function utility in the commercial FLUENT computational fluid dynamics software. The results of sample calculations are reported and compared against the base line cases when no radiation effects are included and when the spectrally gray approximation is used for treatment of radiative heat transfer.
Residential Experience with Proton Exchange Membrane Fuel Cell Systems for Combined Heat and Power
Authors: Massie Darrell D. , Boettner Daisie D. , Massie Cheryl A.
Published: October 2005

As part of a one-year Department of Defense demonstration project, proton exchange membrane fuel cell systems have been installed at three residences to provide electrical power and waste heat for domestic hot water and space heating. The 5kW capacity fuel cells operate on reformed natural gas. These systems operate at preset levels providing power to the residence and to the utility grid. During grid outages, the residential power source is disconnected from the grid and the fuel cell system operates in standby mode to provide power to critical loads in the residence. This paper describes lessons learned from installation and operation of these fuel cell systems in existing residences. Issues associated with installation of a fuel cell system for combined heat and power focus primarily on fuel cell siting, plumbing external to the fuel cell unit required to support heat recovery, and line connections between the fuel cell unit and the home interior for natural gas, water, electricity, and communications. Operational considerations of the fuel cell system are linked to heat recovery system design and conditions required for adequate flow of natural gas, air, water, and system communications. Based on actual experience with these systems in a residential setting, proper system design, component installation, and sustainment of required flows are essential for the fuel cell system to provide reliable power and waste heat.
Parameter Optimization on Combined Gas Turbine-Fuel Cell Power Plants
Authors: Kurz Rainer
Published: October 2005

A thermodynamic model for a gas turbine-fuel cell hybrid is created and described in the paper. The effects of gas turbine design parameters such as compressor pressure ratio, compressor efficiency, turbine efficiency, and mass flow are considered. The model allows to simulate the effects of fuel cell design parameters such as operating temperature, pressure, fuel utilization, and current density on the cycle efficiency. This paper discusses, based on a parametric study, optimum design parameters for a hybrid gas turbine. Because it is desirable to use existing gas turbine designs for the hybrids, the requirements for this hybridization are considered. Based on performance data for a typical 1600hp industrial single shaft gas turbine, a model to predict the off-design performance is developed. In the paper, two complementary studies are performed: The first study attempts to determine the range of cycle parameters that will lead to a reasonable cycle efficiency. Next, an existing gas turbine, that fits into the previously established range of parameters, will be studied in more detail. Conclusions from this paper include the feasibility of using existing gas turbine designs for the proposed cycle.
PEM Fuel Cell Dynamic Model With Phase Change Effect
Authors: Xue X. , Tang J.
Published: October 2005

In this research, a system-level dynamic model accounting for the phase change effect is developed for polymer electrolyte fuel cells (PEMFCs). This model can illustrate the complicated transient behavior of temperature, gas flow, phase change in the anode and cathode channels, and membrane humidification under operating conditions. Simulation indicates that vapor in the cathode channel is more likely to be in the over saturated state and phase change (condensation under large load current situation) then takes place, which leads to higher temperature at cathode channel due to latent heat generation. In the anode channel, on the other hand, the phase change is less likely to occur even if the inlet hydrogen is humidified with a high relative humidity value. The model is partially validated using the experimental data from open literature. A series of analyses are carried out to investigate the underlying physical mechanisms. This model can be used in the optimal design and dynamic control of PEMFCs.
PVD Coated Bipolar Plates for PEM Fuel Cells
Authors: Lee Shuo-Jen , Huang Ching-Han , Chen Yu-Pang , Hsu Chen-Te
Published: October 2005

Aluminum was considered a good candidate material for bipolar plates of the polymer electrolyte membrane (PEM) fuel cells due to its low cost, light weight, high strength and good manufacturability. But there were problems of both chemical and electrochemical corrosions in the PEM fuel cell operating environment. The major goals of this research are to find proper physical vapor deposition (PVD) coating materials which would enhance surface properties by making significant improvements on corrosion resistance and electrical conductivity at a reasonable cost. Several coating materials had been studied to analyze their corrosion resistance improvement. The corrosion rates of all materials were tested in a simulated fuel cell environment. The linear polarization curve of electrochemical method measured by potentiostat instrument was employed to determine the corrosion current. Results of the corrosion tests indicated that all of the coating materials had good corrosion resistance and were stable in the simulated fuel cell environment. The conductivities of the coated layers were better and the resistances changed very little after the corrosion test. At last, single fuel cells were made by each PVD coating material. Fuel cell tests were conducted to determine their performance w.r.t. that was made of graphite. The results of fuel cell tests indicated that metallic bipolar plates with PVD coating could be used in PEM fuel cells.
Exergetic Optimization of a PEM Fuel Cell for Domestic Hot Water Heater
Authors: Saidi M. H. , Abbassi A. , Ehyaei M. A.
Published: October 2005

In this paper, a 5kW PEM fuel cell including burner, steam reformer, and water heater for domestic application has been considered. Water is used for cooling of the fuel cell. Cold water is passed through a cooling channel, warmed up and used for domestic water heating. To increase the efficiency, outlet steam of fuel cell is fed to the reformer. The perfomance of the system is optimized by exergy analysis based on the second law of thermodynamics. Also, the effect of burner, fuel cell temperature and stoichiometric air fuel ratio are investigated. In this analysis, pressure loss in the fuel cell and heat transfer of the cooling channel are taken into account whereas, pressure loss in burner and reformer are neglected. Results show, to minimize the entropy generation, fuel cell temperature must be increased to maximize PEM fuel cell temperature. Also, burner and reformer temperature and stoichiometric air fuel ratio must be decreased to 900K, and λ=2, respectively.
GENERALIZED WEAK WEYL RELATION AND DECAY OF QUANTUM DYNAMICS
Authors: ARAI ASAO
Published: October 2005

Let H be a self-adjoint operator on a Hilbert space [Formula: see text], T be a symmetric operator on [Formula: see text] and K(t)(t ∈ ℝ) be a bounded self-adjoint operator on [Formula: see text]. We say that (T, H, K) obeys the generalized weak Weyl relation (GWWR) if e-itHD(T) ⊂ D(T) for all t ∈ ℝ and Te-itHψ = e-itH(T+K(t))ψ, ∀ψ ∈ D(T) (D(T) denotes the domain of T). In the context of quantum mechanics where H is the Hamiltonian of a quantum system, we call T a generalized time operator of H. We first investigate, in an abstract framework, mathematical structures and properties of triples (T, H, K) obeying the GWWR. These include the absolute continuity of the spectrum of H restricted to a closed subspace of [Formula: see text], an uncertainty relation between H and T (a "time-energy uncertainty relation"), the decay property of transition probabilities |〈ψ,e-itHϕ〉|2 as |t| → ∞ for all vectors ψ and ϕ in a subspace of [Formula: see text], where 〈·,·〉 denotes the inner product of [Formula: see text]. We describe methods to construct various examples of triples (T, H, K) obeying the GWWR. In particular, we show that there exist generalized time operators of second quantization operators on Fock spaces (full Fock spaces, boson Fock spaces and fermion Fock spaces) which may have applications to quantum field models with interactions.
HOMOTOPY OF POSETS, NET-COHOMOLOGY AND SUPERSELECTION SECTORS IN GLOBALLY HYPERBOLIC SPACE-TIMES
Authors: RUZZI GIUSEPPE
Published: October 2005

We study sharply localized sectors, known as sectors of DHR-type, of a net of local observables, in arbitrary globally hyperbolic space-times with dimension ≥ 3. We show that these sectors define, as it happens in Minkowski space, a C*-category in which the charge structure manifests itself by the existence of a tensor product, a permutation symmetry and a conjugation. The mathematical framework is that of the net-cohomology of posets according to J. E. Roberts. The net of local observables is indexed by a poset formed by a basis for the topology of the space-time ordered under inclusion. The category of sectors, is equivalent to the category of 1-cocycles of the poset with values in the net. We succeed in analyzing the structure of this category because we show how topological properties of the space-time are encoded in the poset used as index set: the first homotopy group of a poset is introduced and it is shown that the fundamental group of the poset and one of the underlying space-time are isomorphic; any 1-cocycle defines a unitary representation of these fundamental groups. Another important result is the invariance of the net-cohomology under a suitable change of index set of the net.
PRODUCTIVE USES OF ENERGY FOR RURAL DEVELOPMENT
Authors: Cabraal R. Anil , Barnes Douglas F. , Agarwal Sachin G.
Published: October 2005

▪ Abstract  This review utilizes the Global Environment Facility (GEF) and UN Food and Agricultural Organization (FAO) working definition of “productive uses of energy,” which states “in the context of providing modern energy services in rural areas, a productive use of energy is one that involves the application of energy derived mainly from renewable resources to create goods and/or services either directly or indirectly for the production of income or value.” The definition reflects the shift toward the aspirations of the Millennium Development Goals (MDGs). Traditionally, the productive uses of energy have been rather narrowly defined. The focus has been on the direct impact of energy use on gross domestic product (GDP) and the importance of motive power for agriculture. This conventional view has some utility in understanding the nature of development at the national and regional level; however, in order to respond to international development goals while maintaining pace with an ever-evolving understanding of what development is, it is important to consider how this traditional thinking may be augmented. The earlier thinking about the productive uses of energy needs to be updated with an enhanced understanding of the tremendous impact that energy services have on education, health, and gender equality. Indeed, a refined understanding of energy use has important public policy implications because scarce resources may be guided into investments that may achieve the desired national or international development goals.
THE ROLE OF PROTECTED AREAS IN CONSERVING BIODIVERSITY AND SUSTAINING LOCAL LIVELIHOODS
Authors: Naughton-Treves Lisa , Holland Margaret Buck , Brandon Katrina
Published: October 2005

▪ Abstract  The world's system of protected areas has grown exponentially over the past 25 years, particularly in developing countries where biodiversity is greatest. Concurrently, the mission of protected areas has expanded from biodiversity conservation to improving human welfare. The result is a shift in favor of protected areas allowing local resource use. Given the multiple purposes of many protected areas, measuring effectiveness is difficult. Our review of 49 tropical protected areas shows that parks are generally effective at curtailing deforestation within their boundaries. But deforestation in surrounding areas is isolating protected areas. Many initiatives now aim to link protected areas to local socioeconomic development. Some of these initiatives have been successful, but in general expectations need to be tempered regarding the capacity of protected areas to alleviate poverty. Greater attention must also be paid to the broader policy context of biodiversity loss, poverty, and unsustainable land use in developing countries.
On generalized vector quasivariational-like inequality problems
Authors: Khaliq Abdul , Rashid Mohammad
Published: October 2005

We introduce a class of generalized vector quasivariational-like inequality problems in Banach spaces. We derive some new existence results by using KKM-Fan theorem and an equivalent fixed point theorem. As an application of our results, we have obtained as special cases the existence results for vector quasi-equilibrium problems, generalized vector quasivariational inequality and vector quasi-optimization problems. The results of this paper generalize and unify the corresponding results of several authors and can be considered as a significant extension of the previously known results.
Existence of fixed points on compact epilipschitz sets without invariance conditions
Authors: Kamenskii Mikhail , Quincampoix Marc
Published: October 2005

We provide a new result of existence of equilibria of a single-valued Lipschitz function "Equation missing" on a compact set "Equation missing" of "Equation missing" which is locally the epigraph of a Lipschitz functions (such a set is called epilipschitz set). Equivalently this provides existence of fixed points of the map "Equation missing". The main point of our result lies in the fact that we do not impose that "Equation missing" is an "inward vector" for all point "Equation missing" of the boundary of "Equation missing". Some extensions of the existence of equilibria result are also discussed for continuous functions and set-valued maps.
An explicit construction of sunny nonexpansive retractions in Banach spaces
Authors: Aleyner Arkady , Reich Simeon
Published: October 2005

An explicit algorithmic scheme for constructing the unique sunny nonexpansive retraction onto the common fixed point set of a nonlinear semigroup of nonexpansive mappings in a Banach space is analyzed and a proof of convergence is given.
Fixed point results and their applications to Markov processes
Authors: Heikkilä S
Published: October 2005

New existence and comparison results are proved for fixed points of increasing operators and for common fixed points of operator families in partially ordered sets. These results are then applied to derive existence and comparison results for invariant measures of Markov processes in a partially ordered Polish space.
Weak and strong convergence theorems for nonexpansive semigroups in Banach spaces
Authors: Atsushiba Sachiko , Takahashi Wataru
Published: October 2005

We introduce an implicit iterative process for a nonexpansive semigroup and then we prove a weak convergence theorem for the nonexpansive semigroup in a uniformly convex Banach space which satisfies Opial's condition. Further, we discuss the strong convergence of the implicit iterative process.
Common fixed point theorems for compatible self-maps of Hausdorff topological spaces
Authors: Jungck Gerald F
Published: October 2005

The concept of proper orbits of a map "Equation missing" is introduced and results of the following type are obtained. If a continuous self-map "Equation missing" of a Hausdorff topological space "Equation missing" has relatively compact proper orbits, then "Equation missing" has a fixed point. In fact, "Equation missing" has a common fixed point with every continuous self-map "Equation missing" of "Equation missing" which is nontrivially compatible with "Equation missing". A collection of metric and semimetric space fixed point theorems follows as a consequence. Specifically, a theorem by Kirk regarding diminishing orbital diameters is generalized, and a fixed point theorem for maps with no recurrent points is proved.
Quasicontraction nonself-mappings on convex metric spaces and common fixed point theorems
Authors: Gajić Ljiljana , Rakočević Vladimir
Published: October 2005

We consider quasicontraction nonself-mappings on Takahashi convex metric spaces and common fixed point theorems for a pair of maps. Results generalizing and unifying fixed point theorems of Ivanov, Jungck, Das and Naik, and Ćirić are established.
An approximation of solutions of variational inequalities
Authors: Li Jinlu , Rhoades BE
Published: October 2005

We use a Mann-type iteration scheme and the metric projection operator (the nearest-point projection operator) to approximate the solutions of variational inequalities in uniformly convex and uniformly smooth Banach spaces.
Transfer positive hemicontinuity and zeros, coincidences, and fixed points of maps in topological vector spaces
Authors: Włodarczyk K , Klim D
Published: October 2005

Let "Equation missing" be a real Hausdorff topological vector space. In the present paper, the concepts of the transfer positive hemicontinuity and strictly transfer positive hemicontinuity of set-valued maps in "Equation missing" are introduced (condition of strictly transfer positive hemicontinuity is stronger than that of transfer positive hemicontinuity) and for maps "Equation missing" and "Equation missing" defined on a nonempty compact convex subset "Equation missing" of "Equation missing", we describe how some ideas of K. Fan have been used to prove several new, and rather general, conditions (in which transfer positive hemicontinuity plays an important role) that a single-valued map "Equation missing" has a zero, and, at the same time, we give various characterizations of the class of those pairs "Equation missing" and maps "Equation missing" that possess coincidences and fixed points, respectively. Transfer positive hemicontinuity and strictly transfer positive hemicontinuity generalize the famous Fan upper demicontinuity which generalizes upper semicontinuity. Furthermore, a new type of continuity defined here essentially generalizes upper hemicontinuity (the condition of upper demicontinuity is stronger than the upper hemicontinuity). Comparison of transfer positive hemicontinuity and strictly transfer positive hemicontinuity with upper demicontinuity and upper hemicontinuity and relevant connections of the results presented in this paper with those given in earlier works are also considered. Examples and remarks show a fundamental difference between our results and the well-known ones.
On the ratio of Pearson type VII and Bessel random variables
Authors: Nadarajah Saralees , Kotz Samuel
Published: October 2005

The exact distribution of the ratio |X/Y| is derived when X and Y are, respectively, Pearson type VII and Bessel function random variables distributed independently of each other. The work is motivated by previously published approximate relationships between these two distributions. An application of the result is
provided by computing “correction factors” for some of these approximations.
Profitability, investment, and efficiency wages
Authors: Faria João Ricardo
Published: October 2005

We examine a model that blends the neoclassical theory of investment with an intertemporal efficiency wage model with turnover costs. Investment decisions in capital are associated with the allocation of labor and the determination of efficiency
wages. The model relates Tobin's q to efficiency wages and, in particular, to the Solow condition. It provides a general
framework to analyze firm's intertemporal choices of capital, labor and efficiency wages.
A production model for a flexible production system and products
with short selling season
Authors: Khouja Moutaz , Mehrez Abraham
Published: October 2005

We address a practical problem faced by many firms. The problem is
deciding on the production levels for a product that has a very short selling season. The firm has a full period to produce and meet a lumpy demand which occurs at the end of the period. The product is no longer demanded after the end of the period. A constant production rate which minimizes average unit cost may increase holding costs. Varying the production rate at discrete points in time may increase production costs but may also decrease holding costs. In addition, allowing changes in the production rate enables the incorporation of forecast revisions into the production plan. Therefore, the best production plan depends on the flexibility of the production system and on the holding cost. In this paper, we formulate and solve a model of this production planning problem. Two models are developed to deal with two types of the average unit cost function. Numerical examples are used to illustrate the results of the model.
Partially clairvoyant scheduling for aggregate constraints
Authors: Subramani K.
Published: October 2005

The problem of partially clairvoyant scheduling is concerned with checking whether an ordered set of jobs, having nonconstant execution times and subject to a collection of imposed constraints, has a partially clairvoyant schedule. Variability of
execution times of jobs and nontrivial relationships constraining their executions, are typical features of real-time systems. A partially clairvoyant scheduler parameterizes the schedule, in that the start time of a job in a sequence can depend upon the execution times of jobs that precede it, in the sequence. In real-time scheduling, parameterization of the schedule plays an important role in extending the flexibility of the scheduler, particularly in the presence of variable execution times. It has been shown that the existence of partially clairvoyant schedules can be determined in polynomial time, when the constraints are restricted to be “standard,” that is, relative timing
constraints. In this paper, we extend the class of constraints for which partially clairvoyant schedules can be determined efficiently, to include aggregate constraints. Aggregate constraints form a strict superset of standard constraints and can be used to model performance metrics.
Comparisons and Homology in Adult and Developing Vertebrate Central Nervous Systems
Authors: Pritz Michael B.
Published: October 2005

Comparisons of characters in both adult and developing vertebrate central nervous systems require an understanding of the concept of homology. This article begins with a definition of homology in adult animals and then discusses criteria and methodology used to make appropriate comparisons of characters at a variety of hierarchical levels. Crucial to such an analysis is the methodology employed by neurocladistics to ensure meaningful comparisons. Then, a similar approach is used to address these identical problems in embryos. Concerns unique to comparisons of developing central nervous systems are enumerated. In addition, a number of special features of central nervous system formation and organization in both adults and embryos are discussed within the framework of homology and neurocladistics. Lastly, the concept of field homology as applied to vertebrate central nervous system characters is addressed.
Evolutionary Patterns of Cranial Nerve Efferent Nuclei in Vertebrates
Authors: Gilland Edwin , Baker Robert
Published: October 2005

All vertebrates have a similar series of rhombomeric hindbrain segments within which cranial nerve efferent nuclei are distributed in a similar rostrocaudal sequence. The registration between these two morphological patterns is reviewed here to highlight the conserved vs. variable aspects of hindbrain organization contributing to diversification of efferent sub-nuclei. Recent studies of segmental origins and migrations of branchiomotor, visceromotor and octavolateral efferent neurons revealed more segmental similarities than differences among vertebrates. Nonetheless, discrete variations exist in the origins of trigeminal, abducens and glossopharyngeal efferent nuclei. Segmental variation of the abducens nucleus remains the sole example of efferent neuronal homeosis during vertebrate hindbrain evolution. Comparison of cranial efferent segmental variations with surrounding intrinsic neurons will distinguish evolutionary changes in segment identity from lesser transformations in expression of unique neuronal types. The diversification of motoneuronal subgroups serving new muscles and functions appears to occur primarily by elaboration within and migration from already established segmental efferent pools rather than by de novo specification in different segmental locations. Identifying subtle variations in segment-specific neuronal phenotypes requires studies of cranial efferent organization within highly diverse groups such as teleosts and mammals.
Time-Lapse Analysis Reveals a Series of Events by Which Cranial Neural Crest Cells Reroute around Physical Barriers
Authors: Kulesa Paul M. , Lu Carole C. , Fraser Scott E.
Published: October 2005

Segmentation is crucial to the development of the vertebrate body plan. Underlying segmentation in the head is further revealed when cranial neural crest cells emerge from even numbered rhombomeres in the hindbrain to form three stereotypical migratory streams that lead to the peripheral branchial arches. To test the role of intrinsic versus extrinsic cues in influencing an individual cell’s trajectory, we implanted physical barriers in the chick mesoderm, distal to emerging neural crest cell stream fronts. We analyzed the spatio-temporal dynamics as individual neural crest cells encountered and responded to the barriers, using time-lapse confocal imaging. We find the majority of neural crest cells reach the branchial arch destinations following a repeatable series of events by which the cells overcome the barriers. Even though the lead cells become temporarily blocked by a barrier, cells that follow from behind find a novel pathway around a barrier and become de novo leaders of a new stream. Surprisingly, quantitative analyses of cell trajectories show that cells that encounter an r3 barrier migrate significantly faster but less directly than cells that encounter an r4 barrier, which migrate normally. Interestingly, we also find that cells temporarily blocked by the barrier migrate slightly faster and change direction more often. In addition, we show that cells can be forced to migrate into normally repulsive territory. These results suggest that cranial neural crest cell trajectories are not intrinsically determined, that cells can respond to minor alterations in the environment and re-target a peripheral destination, and that both intrinsic and extrinsic cues are important in patterning.
Specification and Patterning of Neural Crest Cells During Craniofacial Development
Authors: Trainor Paul A.
Published: October 2005

Craniofacial evolution is considered fundamental to the origin of vertebrates and central to this process was the formation of a migratory, multipotent cell population known as the neural crest. The number of cell types that arise from the neural crest is truly astonishing as is the number of tissues and organs to which the neural crest contributes. In addition to forming melanocytes as well as many neurons and glia in the peripheral nervous system, neural crest cells also contribute much of the cartilage, bone and connective tissue of the face. These multipotent migrating cells are capable of self renewing decisions and based upon these criteria are often considered stem cells or stem cell-like. Rapid advances in our understanding of neural crest cell patterning continue to shape our appreciation of the evolution of neural crest cells and their impact on vertebrate craniofacial morphogenesis.
Vasoconstrictive Effect of Angiotensin IV in Isolated Rat Basilar Artery Independent of AT1 and AT2 Receptors
Authors: Faure Sebastien , Javellaud James , Achard Jean-Michel , Oudart Nicole
Published: October 2005

The effect of angiotensin IV (AngIV) was studied in freshly isolated rat basilar arteries (BAs) perfused at a constant rate. AngIV had no effect on basal BA perfusion pressure, but induced a marked concentration-dependent contraction in vessels precontracted by a 50-mM KCl solution (EC50 = 44.5 ± 16 nM). This contraction was unaffected by the angiotensin AT1 receptor antagonist candesartan or the angiotensin AT2 receptor blocker PD123319, but was markedly inhibited by two different specific AT4 receptor antagonists, Nle1-Leu3¥(CH2-NH2)3–4-AngIV and divalinal-AngIV. Removal of the endothelium abolished the contractile response to AngIV, and pretreatment of endothelium-intact arteries with the endothelin ETA/ETB receptors inhibitor PD142893 blocked the AngIV-induced contraction to the same extent. In BA pretreated with endothelin-1 (ET-1; 0.01 µM), AngIV-induced a concentration-dependent contraction, shifted to the left, compared with that observed with KCl precontraction, unaffected by candesartan but completely abolished by Nle1-Leu3¥(CH2-NH2)3–4-AngIV. The contractile effect was not affected by endothelium removal in the presence of exogenous ET-1, in contrast to KCl pretreated BA, suggesting that endothelium was mandatory to unmask the effect of AngIV as a source of endogenous ET-1 release. Taken together, these results indicate that low (nanomolar) concentrations of AngIV exert a constrictive effect mediated by its specific binding site AT4 in the rat BA, and that this vasoactive effect is indirect and involves endogenous endothelin(s).
Immunogenetics of Type 1 Diabetes
Authors: Kim Mimi S. , Polychronakos Constantin
Published: October 2005

The T-cell mediated autoimmune process that destroys pancreatic β cells in type 1 diabetes (T1D) is a complex phenotype influenced by multiple genetic and environmental factors. Human leukocyte antigen (HLA) accounts for about half of the genetic susceptibility, through a large variety of protective and predisposing haplotypes. Other important loci associated with T1D, with much smaller effects than HLA, include the insulin variable number of tandem repeats, PTPN22, and CTLA-4. Detecting the association and confirming it beyond doubt is only the first step. Identifying the functional variant from among a block of polymorphisms in tight linkage disequilibrium and determining its biological consequences can be an even more challenging task. It is hoped that the identification of additional loci and functional analysis of known ones, no matter how small each individual effect is, will provide: (1) pathophysiological insights necessary for the development of preventive interventions; (2) risk prediction to identify individuals that can benefit from them, and (3) potentially, identification of distinct subgenotypes, with different immune dysregulation pathways leading to the common disease phenotype that may respond to different preventive interventions.
Relationship between Delusions and Regional Cerebral Blood Flow in Alzheimer’s Disease
Authors: Nakano Seigo , Yamashita Fumio , Matsuda Hiroshi , Kodama Chiine , Yamada Tatsuo
Published: October 2005

To investigate the association between delusions and cerebral functional deficits in Alzheimer’s disease (AD), we evaluated probable AD patients with and without delusions. Methods: Functional brain imaging was performed by single photon emission computed tomography with technetium-99m-labeled ethyl cysteinate dimer (99mTc-ECD) in 64 AD patients and 76 age-matched normal healthy volunteers. SPECT data were analyzed by statistical parametric mapping. Results: In AD patients, no differences were found in age and cognitive activities between those with (n = 25) and without (n = 39) delusions. Compared with normal healthy volunteers, AD patients had significantly decreased perfusion in the posterior cingulate gyri, precunei, and parietal association cortex. Moreover, in the patients with delusions, perfusion was significantly decreased in the frontal lobe with right side dominance. In the comparison between the patients with and without delusions, the patients with delusions had significantly decreased perfusion in the prefrontal cortex, anterior cingulate gyri, inferior to middle temporal cortices, and parietal cortex of the right hemisphere (p < 0.01). Conclusion: The functional deficits in the right hemisphere may be the cause of delusions in AD.
Regional Variability in the Prevalence of Cerebral White Matter Lesions: An MRI Study in 9 European Countries (CASCADE)
Authors: Launer L.J. , Berger K. , Breteler M.M.B. , Dufouil C. , Fuhrer R. , Giampaoli S. , Nilsson L.-G. , Pajak A. , de Ridder M. , van Dijk E.J. , Sans S. , Schmidt R. , Hofman A.
Published: October 2005

White matter lesions (WML) on MRI of the brain are common in both demented and nondemented older persons. They may be due to ischemic events and are associated with cognitive and physical impairments. It is not known whether the prevalence of these WML in the general population differs across European countries in a pattern similar to that seen for coronary heart disease. Here we report the prevalence of WML in 1,805 men and women drawn from population-based samples of 65- to 75-year-olds in ten European cohorts. Data were collected using standardized methods as a part of the multicenter study CASCADE (Cardiovascular Determinants of Dementia). Centers were grouped by region: south (Italy, Spain, France), north (Netherlands, UK, Sweden), and central (Austria, Germany, Poland). In this 10-year age stratum, 92% of the sample had some lesions, and the prevalence increased with age. The prevalence of WML was highest in the southern region, even after adjusting for differences in demographic and selected cardiovascular risk factors. Brain aging leading to disabilities will increase in the future. As a means of hypothesis generation and for health planning, further research on the geographic distribution of WML may lead to the identification of new risk factors for these lesions.
Chronic Meningitis in Thailand
Authors: Helbok R. , Pongpakdee S. , Yenjun S. , Dent W. , Beer R. , Lackner P. , Bunyaratvej P. , Prasert B. , Vejjajiva A. , Schmutzhard E.
Published: October 2005

The charts of 114 consecutive patients with chronic meningitis admitted to a general hospital in Bangkok, Thailand, between 1993 and 1999 were retrospectively reviewed. The most common causative agents were Cryptococcus neoformans (54%) and Mycobacterium tuberculosis (37%). HIV and other underlying diseases had a major impact on the presentation of chronic cryptococcal meningitis patients. Compared to HIV-negative cryptococcal meningitis patients (21%), HIV-positives (79%) had a significantly lower incidence of focal signs (p = 0.02), hydrocephalus (p = 0.03) and seizures (p = 0.001) during hospital stay, furthermore, a lower leucocyte level, a significantly higher glucose level (p = 0.02) and a lower protein level (p = 0.03) in the first cerebrospinal fluid examination. Of the 43 patients with chronic tuberculous meningitis, only 3 were HIV positive. Focal neurologic deficits were found more frequently in tuberculous meningitis patients (p = 0.001) when compared to cryptococcal meningitis patients without HIV. Cerebral infarction on cerebral CT was indicative of tuberculous meningitis. Cryptococcal meningitis patients with HIV infection had a worse outcome compared to non-AIDS patients. Advanced stage of the disease on admission, decreased level of consciousness prior to and on the admission day and raised intracranial pressure above 40 cm H2O at any given time were predictive of a poor outcome in tuberculous meningitis patients.
Plasma Total Homocysteine Levels in Stroke Patients Screened for the Vitamin Intervention for Stroke Prevention Clinical Trial in the Era of Folate Fortification
Authors: Lutsep Helmi L. , Campbell Stephen , Chambless Lloyd E. , Howard Virginia J. , Toole James F.
Published: October 2005

Folic acid fortification of grain products was mandated in the USA by January 1998 and in Canada by November 1998. It was hypothesized thatscreeningtotal plasma homocysteine levels adjusted for age, sex, race and country that were drawn in stroke patients for the Vitamin Intervention for Stroke Prevention trial from 1997 to 2001 would be steady when fortification was completed. Samples were grouped by years 1997/1998, 1999 and 2000/2001, and adjusted means were calculated using a general linear regression model. In 2,612 US and 1,059 Canadian patients, levels showed no consistent trend in the USA alone, while Canadian levels declined (p = 0.06 overall, 0.0003 in the oldest age group). US levels were 0.39 µmol/l (95% CI: –0.08, 0.85) lower than in Canada. Neither fasting nor time since stroke affected the results.
Quantitative Measures of Gait Characteristics Indicate Prevalence of Underlying Subclinical Structural Brain Abnormalities in High-Functioning Older Adults
Authors: Rosano Caterina , Brach Jennifer , Longstreth Jr. William T. , Newman Anne B.
Published: October 2005

Abnormal gait in high-functioning older adults may indicate underlying subtle structural brain abnormalities. We tested the hypothesis that temporal and spatial parameters of gait, including speed, stride length and double support time, are cross-sectionally associated with white matter hyperintensity, subcortical infarcts or brain atrophy on brain MRI. We examined 321 men and women (mean age = 78.3) participating to the Cardiovascular Health Study who were free of dementia or stroke at the time of the gait assessment. Analyses were set with gait as independent variable and brain MRIs as dependent variables. Gait measures were determined from the footfalls recorded on a 4-meter-long instrumented walking surface, the GaitMat II. Brain MRIs were examined for the presence of white matter hyperintensity (WMG, graded from 0 to 9), brain infarcts (predominantly subcortical) and ventricular enlargement (graded from 0 to 9). Slower gait, shorter stride length and longer double support times were associated with greater prevalence of white matter grade ≧3 (p = 0.02), and at least 1 brain infarct (p = 0.04) independent of age. In multivariate logistic regression models adjusted for demographics and clinical cardiovascular diseases, those with gait speed <1.02 m/s were more likely to have WMG ≧3 and at least 1 brain infarct, compared with those with faster gait – odds ratio (OR): 2.85, 95% confidence interval (95% CI): 1.35, 6.02, and OR: 2.09, 95% CI: 1.04, 4.19. Shorter stride length was also associated with greater probability of having at least 1 brain infarct (gait stride <0.88 vs. >1.10 m: OR: 3.20, 95% CI: 1.49, 6.88), while longer double support times were associated with a greater probability of having WMG ≧3 (double support time >0.19 vs. <0.14 s: OR: 2.3, 95% CI: 1.1, 4.7) independent of demographics and clinical cardiovascular diseases. Gait parameters were not significantly associated with ventricular grade. In summary, in this group of high-functioning older adults, poorer gait speed, shorter stride and longer double support time are associated with high white matter disease and subclinical strokes.
Adjuvant 5-FU-Based Chemoradiotherapy for Patients Undergoing R-1/R-2 Resections for Pancreatic Cancer
Authors: Smeenk Hans G. , Incrocci Luca , Kazemier Geert , van Dekken Herman , Tran Khe T.C. , Jeekel Johannes , van Eijck Casper H.J.
Published: October 2005

Background: Pancreatic cancer is the fifth leading cause of cancer-related death worldwide. Among patients treated with surgery alone, liver metastasis occurs in up to 50%, peritoneal recurrence in 25%, and local recurrence occurs in 50–80% of all patients who underwent resection. Even after a macroscopically curative resection, tumour cells might be observed by microscopy at one or more edges of the resected specimen in 20–51% (R-1) which might account for the high local recurrence. Aim of the Study: An analysis was performed in 54 patients who underwent an irradical resection (R-1 and R-2) for pancreatic cancer. 33 patients were treated with chemoradiotherapy. To evaluate the effect of therapy on survival and recurrence, this group was retrospectively compared to a group of 21 patients that did not receive chemoradiotherapy. Methods: Radiotherapy consisted of 50 Gy external upper abdomen radiation in two courses of 3 weeks, concomitant with intravenous 5-FU 25 mg/kg/24 h continuously on the first 4 days of each treatment course. Follow-up was performed mainly by CT scanning and occasionally by US and was completed for all but 1 patient. Results: The treatment protocol was completed in all patients without complications. Local recurrence was found in 6 (18%) patients in the group of patients who received adjuvant therapy versus 16 (48%) patients in the group that did not receive adjuvant therapy (p = 0.001). The median survival time for the treated group was 12.8 vs. 13.7 months in the group that did not receive chemoradiotherapy (p = 0.9). Three (9%) patients are still alive 140, 88 and 70 months after receiving surgery and adjuvant treatment. Conclusion: Adjuvant chemoradiotherapy clearly gives a significant better local control. However, treatment with 5-FU and radiotherapy does not improve survival due to distant metastases. This therapy probably prolongs survival in only a few patients. More effective treatment methods have to be designed to prevent metastatic disease and improve survival.
Is Hepcidin a Link between Anemia, Inflammation and Liver Function in Hemodialyzed Patients?
Authors: Małyszko Jolanta , Małyszko Jacek S. , Hryszko Tomasz , Pawlak Krystyna , Mysliwiec Michał
Published: October 2005

Background: Hepcidin synthesis in hepatocytes is modulated in response to anemia, hypoxia or inflammation. A cross-sectional study was performed to assess hepcidin correlations with markers of iron status, erythropoietin therapy and markers of inflammation in hemodialyzed patients and in the healthy volunteers. Methods: Iron status, complete blood count, creatinine, albumin, lipids were assessed using standard laboratory methods. Hepcidin and high-sensitivity CRP were measured using commercially available kits. Results: Serum iron, TIBC, TSAT, erythrocyte count, Hb, Ht, platelet count, albumin, and cholesterol were lower, whereas ferritin and hepcidin were higher in hemodialyzed patients over controls. Hepcidin correlated positively with triglycerides, albumin, aspartate aminotransferase, lymphocyte count, ferritin and erythropoietin dose and negatively with erythrocyte count, Hb, and Ht in hemodialyzed patients. In multiple regression analysis, triglycerides (β value was 0.28, p = 0.02) and albumin (β value was –0.31, p = 0.006) were correlates of hepcidin in hemodialyzed patients. Conclusions: Elevated hepcidin levels in hemodialyzed patients may be due to functional iron deficiency and anemia. Liver plays an important role in the synthesis of hepcidin. Low-grade inflammation, frequently found in hemodialyzed patients, might also contribute to elevated hepcidin concentration. Hypothesis that hepcidin might link anemia, inflammation and liver function in kidney disease should be further evaluated.
Towards an integrative theory of religion and politics
Authors: Leustean Lucian
Published: October 2005

In the social sciences, debate on the relationship between religion and politics is mainly the subject of analysis in the sociology of religion and the theory of international relations. While each of these fields promotes different approaches to study their interdependency. The individual's perception of religion and politics is neglected by current research. The faithful, who participates in religious ceremonies, listening and behaving according to specific religious teachings, actively engaging in the liturgical life of the institutional form of his religion, has a specific way of understanding the relationship between religion and politics. I argue that this aspect is under-researched and misrepresented in the literature of sociology and international relations. However, a more complex analysis is offered by the study of nationalism, and especially by its ethnosymbolic approach, which includes at the micro and macro societal level the presence of myths and symbols as part of the individual's and the nation's life. An integrative theory analysing the connection between religion and politics takes into account the role of myths and symbols from the perspectives of both individuals and ethnic communities.
Reappropriating 'religion'? Constructively reconceptualising (human) science and the study of religion
Authors: Orye Lieve
Published: October 2005

In the study of religion there is much discussion, to put it simply, between those arguing for a humanistic or for other forms of a non-reductionist study of religion and those opposing "the humanistic manoeuvre" and what they see as attempts to retheologise the discipline. Donald Wiebe, whose work occupies centre stage in this article, participates extensively in these debates and is a fervent spokesperson for the latter group. In this article I want to inject in these debates Latour's constructivist perspective on science. Such a perspective involves a call to "go beyond the centrality of beliefs" and hence involves a quite different view on human beings and science from those underlying the debates. Similarities with Cantwell Smith's work are shown and a suggestion is made to jointly discover/construct a symmetrical anthropology that will be useful to the study of religion. The main argument, however, is that from this new perspective, which should stimulate renewed debate about "the role of belief" and other issues, the warnings by Don Wiebe against the introduction of extra-scientific motives and against a blurring of the line between religion and the study of religion remain valid.