bluuebunny/crossref_metadata_2025 huggingface dataset:
Thomas-Fermi fields for molecules with tetrahedral and octahedral symmetry
Authors: March N. H.
Published: November 2008

The Thomas-Fermi method has been applied to molecules with tetrahedral or octahedral symmetry in the approximation in which the nuclei of the outer atoms are smeared out over the surface of a sphere. Solutions are given for the molecules CH4, CF4, CCl4, SiH4, SiF4 and SF6, and using the results presented here it will not be a difficult matter to obtain the solutions for other molecules if they should be required.

A comparison of the results for CH4 with those of Buckingham, Massey and Tibbs shows that whilst for such a light molecule the charge distribution is somewhat poor, the potential is already in good agreement with the results of the Hartree self-consistent field method. For CCl4, however, the approximation of smoothing out all the protons appears to break down. An alternative approximation in which the K and L shell electrons are compressed into the nucleus and the modified nuclear charges smoothed, has been investigated and appears to give more reasonable results.

A discussion of the energy has been given, but the method is not sufficiently accurate to be of value for energetic considerations.
Dimension subgroups modulo n
Authors: Moran Siegfried
Published: November 2008

Let G be an arbitrary group and Zn(G) denote the group algebra of G over the integers modulo n. If δi(G) denotes ith power of the augmentation ideal δ(G) of Zn(G), then

is easily seen to be a normal subgroup of G. It is denoted by Di, n(G) and is called ith dimension subgroup of G modulo n. It can be shown that these dimension subgroups are determined by the dimension subgroups modulo a power of a prime p. Hence we shall restrict our attention to these dimension subgroups.
A remark on topologies for characteristic functions
Authors: Kendall David , Lamperti John
Published: November 2008

Let M1 denote the set of Borel probability measures on the real line and M1 the space of their Fourier transforms, or ‘characteristic functions’. It is well known that the natural correspondence between M1 and M1 is in fact a homeomorphism, provided M1 is endowed with the usual weak topology relative to bounded continuous functions (which topology can be metrized by the construction of Lévy) and that M1 is given the topology (also metric) appropriate to locally uniform convergence, which we call the ‘compact-open’ topology. In particular, if

where μn ∈ M1 (and so φn ∈ M1), then φn(λ)→φ0(λ) uniformly on all compact sets if and only if μn ⇒ μ0 (weak convergence). However, the continuity theorem for characteristic functions implies that even if it is only known that φn(λ)→φ0 pointwise (for all λ), the conclusion that μn ⇒ μ0 is still valid. This raises a question as to whether the pointwise (i.e. product) topology for M1 might not, in fact, be equivalent to the compact-open one, since the corresponding notions of sequential convergence do coincide. The purpose of this note is to show that the answer is negative, even in a much more general setting.
Free subgroups of free abelian topological groups
Authors: Katz E. , Morris S. A. , Nickolas P.
Published: November 2008

In this paper we prove a theorem which gives general conditions under which the free abelian topological group F(Y) on a space Y can be embedded in the free abeian topological group F(X) on a space X.
Comparing Id and Haskell in a Monte Carlo photon transport code
Authors: Hammes Jeffrey , Lubeck Olaf , Böhm Wim
Published: November 2008

In this paper we present functional Id and Haskell versions of a large Monte Carlo radiation transport code, and compare the two languages with respect to their expressiveness. Monte Carlo transport simulation exercises such abilities as parsing, input/output, recursive data structures and traditional number crunching, which makes it a good test problem for languages and compilers. Using some code examples, we compare the programming styles encouraged by the two languages. In particular, we discuss the effect of laziness on programming style. We point out that resource management problems currently prevent running realistically large problem sizes in the functional versions of the code.
Formal basis for the refinement of rule based transition systems
Authors: Clark A. N
Published: November 2008

This paper makes a contribution to the refinement of systems which involve search by proposing a simple non-deterministic model for rule based transition systems and using this to define a meaning for rule based refinement which allows each stage of the software development path to be verified with respect to the previous stage. The proposal allows a system which involves search to be specified in terms of all the possible outcomes. Each stage of refinement will introduce complexity to the rules and therefore develop the search space in ever more sophisticated ways. At each stage of the refinement it will be possible to be precise about which collections of outcomes have been deleted, thereby achieving a verified (prototype) implementation.
Some lattice-based scientific problems, expressed in Haskell
Authors: Carpenter D. B. , Glaser H.
Published: November 2008

The paper explores the application of a lazy functional language, Haskell, to a series of grid-based scientific problems—solution of the Poisson equation, and Monte Carlo simulation of two theoretical models from statistical and particle physics. The implementations introduce certain abstractions of grid topology, making extensive use of the polymorphic features of Haskell. Updating is expressed naturally through use of infinite lists, exploiting the laziness of the language. Evolution of systems is represented by arrays of interacting streams.
Haskore music notation – An algebra of music –
Authors: Hudak Paul , Makucevich Tom , Gadde Syam , Whong Bo
Published: November 2008

We have developed a simple algebraic approach to music description and composition calledHaskore. In this framework, musical objects consist of primitive notions such as notes and rests, operations to transform musical objects such as transpose and tempo-scaling, and operations to combine musical objects to form more complex ones, such as concurrent and sequential composition. When these simple notions are embedded into a functional language such as Haskell, rather complex musical relationships can be expressed clearly and succinctly. Exploiting the algebraic properties of Haskore, we have further defined a notion ofliteral performance(devoid of articulation) through whichobservationally equivalentmusical objects can be determined. With this basis many useful properties can be proved, such as commutative, associative, and distributive properties of various operators. An algebra of music thus surfaces.
Multivariate piecewise polynomials
Authors: de Boor C.
Published: November 2008

This article was supposed to be on ‘multivariate splines». An informal survey, taken recently by asking various people in Approximation Theory what they consider to be a ‘multivariate spline’, resulted in the answer that a multivariate spline is a possibly smooth piecewise polynomial function of several arguments. In particular the potentially very useful thin-plate spline was thought to belong more to the subject of radial basis funtions than in the present article. This is all the more surprising to me since I am convinced that the variational approach to splines will play a much greater role in multivariate spline theory than it did or should have in the univariate theory. Still, as there is more than enough material for a survey of multivariate piecewise polynomials, this article is restricted to this topic, as is indicated by the (changed) title.
Domain decomposition algorithms
Authors: Chan Tony F. , Mathew Tarek P.
Published: November 2008

Domain decomposition refers to divide and conquer techniques for solving partial differential equations by iteratively solving subproblems defined on smaller subdomains. The principal advantages include enhancement of parallelism and localized treatment of complex and irregular geometries, singularities and anomalous regions. Additionally, domain decomposition can sometimes reduce the computational complexity of the underlying solution method.

In this article, we survey iterative domain decomposition techniques that have been developed in recent years for solving several kinds of partial differential equations, including elliptic, parabolic, and differential systems such as the Stokes problem and mixed formulations of elliptic problems. We focus on describing the salient features of the algorithms and describe them using easy to understand matrix notation. In the case of elliptic problems, we also provide an introduction to the convergence theory, which requires some knowledge of finite element spaces and elementary functional analysis.
An introduction to numerical methods for stochastic differential equations
Authors: Platen Eckhard
Published: November 2008

This paper aims to give an overview and summary of numerical methods for the solution of stochastic differential equations. It covers discrete time strong and weak approximation methods that are suitable for different applications. A range of approaches and results is discussed within a unified framework. On the one hand, these methods can be interpreted as generalizing the well-developed theory on numerical analysis for deterministic ordinary differential equations. On the other hand they highlight the specific stochastic nature of the equations. In some cases these methods lead to completely new and challenging problems.
Ionospheric signatures of sudden stratospheric warming: Ion temperature at middle latitude
Authors: Goncharenko Larisa , Zhang Shun‐Rong
Published: November 2008

Sudden stratospheric warming (SSW) is a large‐scale meteorological process in the winter hemisphere lasting several days or weeks. The Incoherent Scatter World Day campaign conducted on January 17–February 1, 2008 was arranged during a minor SSW event and focuses on studies of thermospheric and ionospheric response to stratospheric changes. We analyze ion temperature observations at 100–300 km height obtained by the Millstone Hill incoherent scatter radar (42.6°N, 288.5°E). Alternating regions of warming in the lower thermosphere and cooling above 150km altitude were observed by the radar. We use National Center for Environmental Prediction (NCEP) temperature data at 10hPa (∼30km) level and the F10.7 and Ap indices to identify any cause‐effect relationship between observed variations in the temperature and stratospheric warming event. We conclude that the seasonal trend, solar flux and geomagnetic activity cannot account for the observed warming and cooling temperature variation and suggest that this variation is associated with stratospheric warming. This study demonstrates a link between the lower atmosphere and the ionosphere which has not been considered before and indicates that ionospheric variability as part of space weather should be considered in conjunction with stratospheric changes.
Microsurgical Composite Tissue Transplantation at Difficult Recipient Sites Facilitated by Preliminary Installation of Vein Grafts as Arteriovenous Loops
Authors: Ritter Edmond F. , Anthony James P. , Levin L. Scott , Demas Christopher P. , Klitzman Bruce , Skarada Doug , Serafin Donald
Published: November 2008

In microvascular surgery when local recipient vessels are inadequate, vein grafting is required. There are several potential inherent disadvantages of immediate vein grafting, including the development of graft thrombosis or leakage, an increased opportunity for technical errors, and an increased number of anastomoses in series. All of these may contribute to a higher failure rate for composite-tissue transplantation requiring vein grafts. The authors hypothesized that in cases where vein grafting is obviously required, the creation of a temporary, looped, arteriovenous fistula (AVF) would reduce the morbidity of vein grafting, by allowing the detection of thrombosis or technical errors predisposing to thrombosis prior to free-tissue transplantation. Since delaying the division of an AVF for 5 or more days may allow time for healing of the endothelium at the AVF anastomotic site, the hypothesis was that composite-tissue transplantation whose vein grafts were installed as an AVF divided in a delayed manner, might have better patency than those in which vein grafts were installed at the time of reconstruction.

This study reviews the results of 16 patients (8 females, 8 males) who underwent 17 microvascular reconstructions using AVFs. Patient courses and outcomes were compared between those undergoing immediate (8 patients) and delayed (7 patients) AVF construction, division, and free-tissue transplantation. There was a low patency rate for AVFs which were divided in a delayed fashion (2 of 7 patients, 29 percent), compared with those which were immediately divided (10 of 10, 100 percent). These results suggest that, in spite of a strong theoretical basis for delayed division of the AVF, delayed harvesting of the AVF is empirically associated with a higher thrombosis rate (p = 0.0048, Fishers exact test).
Adenoidzystisches Karzinom der Tränendrüse
Authors: Holz F. G. , Tetz M. , Born I. A. , Völcker H. E.
Published: November 2008

Eine 38jährige Patientin entwickelte eine periphere Abduzensparese zunächst ohne neuroradiologischen Befund. Ein Jahr später traten auf derselben Seite eine inkomplette Okulomotoriusparese, Sensibilitätsstörungen im Bereich des ersten und zweiten Trigeminusastes, eine eingeschränkte Tränenproduktion sowie ein im Bereich des lateralen Oberlids palpabler Tumor auf. Das Kernspintomogramm zeigte eine orbitale Raumforderung mit Ausdehnung bis in den Sinus cavernosus, bei der es sich entsprechend des Probeexzisionsbefundes um ein adenoidzystisches Tränendrüsenkarzinom handelte. Daraufhin folgte eine Exenteratio orbitae mit postoperativer Bestrahlung. Histopathologisch wies der Tumor vorwiegend basaloide, daneben aber auch cribriforme und tubuläre Differenzierungsanteile auf. Die immun-histochemische Charakterisierung umfaßte eine positive Reaktion der Marker für Keratin (KL-1 und AE 1 + 3), Vimentin und Egp 34. Die Bestimmung von Ki 67 gestatte eine Aussage über die proliferative Aktivität des Tumors von ca. 15%. Der Fallbericht zeigt, dass auch in Abwesenheit eines Exophthalmus und ohne begleitende Schmerzen ein maligner orbitaler Tumor Ursache einer kombinierten unilateralen Augenmuskel- und Trigeminusparese sein kann. Die Koexpression von Vimentin und Keratin unterstützt die Auffassung, dass das adenoidzystische Karzinom der Tränendrüse seinen Ausgang von pluripotenten Stammzellen des terminalen Gangsystems nimmt.
Resistivity dependent dielectric and magnetic properties of Pb(Fe0.012Ti0.988)O3 nanoparticles
Authors: Verma K. C. , Kotnala R. K. , Thakur N. , Rangra V. S. , Negi N. S.
Published: November 2008

High resistivity in nanostructured Pb(Fe0.012Ti0.988)O3 system prepared by using polyvinyl alcohol (PVA) in chemical route is observed. The PVA acts as a surfactant to limit the particle size. The Fe substitution for Ti controls the chemical stoichiometry and reduces the lattice distortion, i.e., c/a ratio, and hence the transition temperature reduces with Fe content. The phase structure, morphology, particle size, dc resistivity, and dielectric and magnetic properties of Pb(Fe0.012Ti0.988)O3 nanoparticles have been characterized by x-ray diffraction, transmission/scanning electron microscopy, source meter, LCR meter, and vibrating sample magnetometer. The results indicate that the nanosize particles have high resistivity, which improves the dielectric constant at high-frequency region and increases magnetization of the specimens. The observed variable-range-hopping conduction mechanism indicates that Fe doping leads to the occurrence of local defect states in the PbTiO3 lattice. The dispersionless dielectric properties with low loss are observed up to 15 MHz. The dielectric properties are improved than those obtained by the conventional process. The initial permeability values do not exhibit much variation up to ferromagnetic transition temperature after which it falls sharply. The large value of saturation magnetization is observed at room temperature.
The higher flows of harmonic maps and an application to the Virasoro action
Authors: Gagliardo Michael
Published: November 2008

One characteristic of soliton equations is their infinite number of conservation laws. These conservation laws give rise to a hierarchy of partial differential equations. One example is the AKNS hierarchy. Terng and Uhlenbeck, Poisson Actions and Scattering Theory for Integrable Systems, Surveys in Differential Geometry: Integrable Systems (A supplement to J. Diff. Geom.), 4 (1998) described the conservation laws that give rise to the AKNS hierarchy. This hierarchy can also be realized in a loop group setting, where the equations are called the positive flows. The name arises from the power of λ which generates each flow. Terng (Loop Groups and Integrable Systems, Preliminary notes) also showed that in some sense, the harmonic map equation arises as a −1-flow in this hierarchy. The harmonic map equation also has a hierarchy of negative flows. However, these are not differential equations like the positive flows. It remained to be asked how the positive and negative flows relate and if they commute. The answer to the latter question is in the positive. As for the first question, the two hierarchies are part of one larger hierarchy. This was solved by using a more complex loop group and explicitly determining the loop algebra splitting. This splitting has applications to physics and is applied to an example of Schwarz involving the Virasoro action in Sec. VIII.
Exciton scattering approach for branched conjugated molecules and complexes. III. Applications
Authors: Wu Chao , Malinin Sergey V. , Tretiak Sergei , Chernyak Vladimir Y.
Published: November 2008

The exciton scattering (ES) approach is an efficient tool to calculate the excited states electronic structure in large branched polymeric molecules. Using the previously extracted parameters, we apply the ES approach to a number of phenylacetylene-based test molecules. Comparison of ES predictions with direct quantum chemistry results for the excitation energies shows an agreement within several meV. The ES framework provides powerful insights into photophysics of macromolecules by revealing the connections between the molecular structure and the properties of the collective electronic states, including spatial localization of excitations controlled by the energy.
Effect of domain boundaries on the electrical properties of crystalline Gd2O3 thin films
Authors: Laha Apurba , Bugiel E. , Wang J. X. , Sun Q. Q. , Fissel A. , Osten H. J.
Published: November 2008

We report on the effect of domain boundaries on the electrical properties of epitaxial Gd2O3 thin films grown on Si(001) substrates with 4° miscut along [110] azimuth. Dedicated preparation of the substrate surfaces can lead to two different microstructures of epitaxial Gd2O3 layers when grown at identical growth conditions. A substrate surface with terraces of biatomic steps height is the key point to achieve single crystalline epitaxial Gd2O3 layer. Such epi-Gd2O3 layers exhibited significantly lower leakage currents compared with the commonly obtained epitaxial layers with two orthogonal domains. However, for capacitance equivalent thickness below 1 nm, this difference disappears, indicating that for ultrathin layers direct tunneling becomes dominating. Additionally, forming gas annealing can reduce the leakage current by a few orders of magnitude. Here, thinner layers of both structural types exhibited similar electrical properties.
Extensive genomic copy number variation in embryonic stem cells
Authors: Liang Qi , Conte Nathalie , Skarnes William C. , Bradley Allan
Published: November 2008

Recent analysis of the human and mouse genomes has revealed that highly identical duplicated elements account for >5% of the sequence content. These elements vary in copy number between individuals. Copy number variations (CNVs) contribute significantly to genetic differences among individuals and are increasingly recognized as a causal factor in human diseases with different etiologies. In inbred mouse strains, CNVs have been fixed by inbreeding, but they are highly variable among strains. Within strains, de novo germ-line CNVs can occur, leading to interindividual variation. By analyzing the genome of clonal isolates of mouse ES cells derived from common parental lines, we have uncovered extensive and recurrent CNVs. This variation arises during mitosis and can be cotransmitted into the mouse germ line along with engineered alleles, contributing to genetic variability. The frequency and extent of these genomic changes in ES cells suggests that all somatic tissues in individuals will be mosaics composed of variants of the zygotic genome. Human ES (hES) cells and derived somatic lineages may be similarly affected, challenging the concept of a stable somatic genome.
Interferon-γ and interleukin-4 reciprocally regulate CD8 expression in CD8+T cells
Authors: Apte Simon H. , Baz Adriana , Groves Penny , Kelso Anne , Kienzle Norbert
Published: November 2008

The CD8 co-receptor can modulate CD8+T cell function through its contributions to T cell receptor (TCR) binding and signaling. Here we show that IFN-γ and IL-4 exert opposing effects on the expression of CD8α mRNA and surface CD8 protein during CD8+T cell activation. IL-4 caused down-regulation of surface CD8 on ovalbumin (OVA)257–264-specific TCR-transgenic OT-I CD8+T cells activated with OVA257–264-coated antigen presenting cells or polyclonal stimuli, and on wild type CD8+T cells activated with polyclonal stimuli. This effect was enhanced in each case when the cells lacked a functional IFN-γ or IFN-γR gene. When WT or IFN-γ-deficient OT-I CD8+T cells were analyzed 9 days after co-injection with control or IL-4-expressing OVA+tumor cells into RAG-2−/−γc−/−mice, CD8 levels were highest on WT donor cells from mice that received the control tumor and lowest on IFN-γ-deficient donor cells from mice that received the IL-4-expressing tumor. The latter CD8lowcells displayed markedly impaired binding of OVA257–264/MHC tetramers and peptide/MHC-dependent degranulation. The data reveal an unexpected role for IFN-γ in tuning the CD8 co-receptor during primary CD8+T cell activation bothin vitroandin vivo.
Bioassays for testing effects of Al, Cr and Cd using development in the amphibian Pleurodeles waltl and regeneration in the planarian Dugesia etrusca
Authors: Calevro F. , Campani S. , Filippi C. , Batistoni R. , Deri P. , Bucci S. , Ragghianti M. , Mancino G.
Published: November 2008

Historically, water quality studies have been directed toward obtaining physical and chemical measurements on toxicants occurring in the aquatic environment. At present, bioassays are increasingly used as sensitive indicators of pollutant toxicity, since they are rapid, inexpensive, applicable to a variety of toxicants and allow several acute and chronic endpoints to be assessed simultaneously. The analysis of the potential toxicity of heavy metals was conducted on two aquatic model systems, an amphibian, Pleurodeles waltl, and a freshwater planarian, Dugesia etrusca. Aluminum, chromium and cadmium were chosen since human activity has led to a sharp increase of these metals in the environment. Environmentally realistic and supra-environmental concentrations were assayed in short-term toxicity tests. The effects of these metal ions were evaluated by the analysis of both malformations and lethality in amphibian embryos and alterations to planarian regeneration. Aluminum (0.15, 0.75 and 1.5 mmol 1-1) and Cr (0.75 and 1.5 mmol 1-1) were toxic to P. waltl development and both the ions affected planarian regeneration at concentrations ranging from 0.25 to 1.5 mmol 1-1. Cadmium was highly toxic to amphibian embryos at concentrations ranging from 0.18 to 50 μmol 1-1. This metal ion was also highly toxic to planarians, but it did not significantly affect the regeneration process. The results indicate that bioassays with these two organisms are useful to assess the toxic potential of aquatic pollutants.
In situ tests to assess the potential toxicity of aquatic sediments
Authors: Baudo Renato , Beltrami Monica , Rossi Daria
Published: November 2008

This article reviews the methodological approaches currently used to assess the potential toxicity of aquatic sediments. In the past, the main use of in situ tests has been the field validation of results obtained by means of traditional methods (chemical analyses, inventory of the benthic communities, and laboratory toxicity testing). However, in situ techniques could also be used for a preliminary screening of sediment ecological risk assessment. At present, we suggest this approach for environments suspected to be contaminated, limiting the complex (and expensive) studies based on the traditional chemical analyses and laboratory toxicity testing to cases in which the necessity of a complete sediment risk assessment is already proved.
Anna Giardini's journey from atoms to biomolecules
Authors: Aquilanti Vincenzo , Piccirillo Susanna , Speranza Maurizio
Published: November 2008

A summary of Anna Giardini's academic and personal history.
COMPTES RENDUS
Authors: Tottie Gunnel
Published: November 2008

Werner Welte, Negationslinguistik. Ansätze zur Beschreibung und Erklärung von Aspekten der Negation im Englischen
VERTICAL, MONOVOCALIC AND OTHER “IMPOSSIBLE” VOWEL SYSTEMS: A REVIEW OF THE ARTICULATION OF THE KABARDIAN VOWELS
Authors: Wood Sidney A. J.
Published: November 2008

The North West Caucasian language, Kabardian, has become famous for its minimum vowel system, for the controversy concerning the analysis of its vowel phonemes, and for the central role of that analysis in phoneme theory generally and the laryngeal theory in particular. Phonetically, Kabardian is interesting for the extensive assimilation of its few vowel phonemes to the surrounding consonants. Two published descriptions of these assimilations are compared in this article, and the articulatory processes involved are reinterpreted in terms of gestures that shape and tune the vocal tract, as an alternative to the Bell model of vowel articulation. The assimilations are more complex than was expected, some vowel allophones not acquiring articulatory components present in the environments, others appearing to acquire components not present in the environments. It is suggested that this can be explained by the spectral ambiguity of some palatovelar and pharyngovelar (uvular) configurations.
COMPLEMENT CLAUSES IN MEGRELIAN
Authors: Tchantouria Karina Vamling and Revaz
Published: November 2008

Complement clause types include sentence‐like subordinate clauses with indicative and subjunctive verbs as well as verbal noun clauses. Megrelian lacks infinitives. The division between indicative and subjunctive complement clauses is shown to correlate with the distinction between Truth and Action modality complements.
ACTION TIER FORMATION AND ARGUMENT LINKING1
Authors: Nikanne Urpo
Published: November 2008

Abstract. According to Jackendoff (1987b, 1990) conceptual structure consists of, at least, two tiers: the thematic tier (roles Agent (i.e. causer), Theme, Location, Goal, Source, Route) and the action tier (the roles Actor, Undergoer, Patient, and Beneficiary). This paper discusses the assignment of the action tier roles. The theory proposed in this paper abandons the lexical indexing and suggests that action tier role assignment is based on free principles. In Jackendoff's theory (1990) argument linking is primarily based on the action tier and only secondarily on the thematic tier (cf. Foley & Van Valin 1984). According to the present investigation the action tier cannot have any major role in argument linking.
Hybrids between Viola adunca and V. conspersa
Authors: Valentine D. H.
Published: November 2008

The occurrence of presumed hybrids between Viola adunca Sm. and V. conspersa Rchb. on Manitoulin Island, Ontario is reported. Previous evidence for hybridity between these two species is discussed and attention is drawn to the need for further work to confirm the occurrence of hybrids in wild populations.
Predicted extirpation of the dominant demersal fish in a large marine ecosystem: Atlantic cod (Gadus morhua) in the southern Gulf of St. Lawrence
Authors: Swain Douglas P. , Chouinard Ghislain A.
Published: November 2008

Atlantic cod ( Gadus morhua ) was the dominant demersal fish and most important predator in the southern Gulf of St. Lawrence ecosystem as recently as the 1980s. However, productivity of southern Gulf cod has declined, and the population is no longer viable even in the absence of fishing. We conducted population projections taking into account uncertainty in current abundance-at-age and uncertainty or variability in each of the components of population productivity (i.e., rates of recruitment, individual growth, and adult natural mortality). We defined extirpation as a spawning stock biomass less than 1000 t (<0.3% of historical levels). Based on these projections, at its current level of productivity, this population is certain to be extirpated within 40 years in the absence of fishing and in 20 years with fishery removals at the level of the total allowable catch in 2007 and 2008 (2000 t). Elevated natural mortality of adult cod (M) is the main factor contributing to the low productivity of this stock. Because M appears to be increasing, our projections are likely overly optimistic.
Internal curing of mortars by lightweight aggregates and its effects on hydration
Authors: Akcay Burcu , Tasdemir Mehmet Ali
Published: November 2008

This study investigates the effects of lightweight aggregates (LWAs) on heat and degree of hydration in high-strength cementitious materials, in which natural pumice LWAs were used as water reservoirs to provide internal curing for mitigating autogenous deformation. Normal aggregates were substituted by LWAs at three different volume fractions, such as 8%, 16%, and 24% of total volume of mortars. The results show that as the amount of LWAs increased, the autogenous deformation significantly decreased, while the heat of hydration increased slightly. The cement particles can easily find water released from LWAs and consequently, the degree of hydration increased due to internal curing. The addition of LWAs caused a delay in the time to approximately reach the asymptotic value of the nonevaporable water content.
Geographic information system–based visualization system for planning and monitoring of repetitive construction projects
Authors: Sonmez Rifat , Uysal Furkan
Published: November 2008

This study presents a visualization system based on a geographic information system (GIS) for planning and monitoring the progress of construction projects that are repetitive due to their geometrical layout. A prototype system was developed and applied to an actual pipeline project to demonstrate the advantages of the proposed approach. The primary advantage of the system is improved visualization of geographical conditions and their impact on the progress rate. Enhanced visual representation of the schedule and work sequence can be achieved by time–lapse simulation. The system also provides a framework for effective communication of schedule, progress, and geographic information among the project participants. Future enhancements to the prototype system are addressed.
Interval stochastic quadratic programming approach for municipal solid waste management
Authors: Guo P. , Huang G.H. , Li Y.P.
Published: November 2008

In this study, an interval stochastic quadratic programming method (ISQP) is developed through incorporating techniques of chance-constrained programming (CCP) and inexact quadratic programming (IQP) within a general framework. This method improves upon the conventional IQP approaches in uncertainty reflection and risk analysis. Interval stochastic quadratic programming can handle dual uncertainties expressed as interval values and probability distributions, and can deal with nonlinearities in objective function to reflect economies-of-scale effects on the system cost. It can also support the assessment of the risk of violating various constraints, for accomplishing a minimizing system cost. The developed ISQP is applied to a municipal solid waste (MSW) management system with multiple disposal facilities and multiple cities within multiple time periods. Results of the case study indicate that useful solutions for planning MSW management practices have been generated under different probability levels of violating constraints, which are informative and flexible for decision makers. A high system cost is associated with a low risk level of violating constraints, and a low system costs will run into a high probability of violating constraints. There is a tradeoff between the system cost and the constraint-violation risk.
Detection and Genotyping of an Infectious Pancreatic Necrosis Virus from Asymptomatic Rainbow Trout (Oncorhynchus mykiss) Facilities in Mexico
Authors: Guerrero Luis , Herrera Emma , Salinas Juana , Torres Jesús , Montero Ana Bertha , Barrón Blanca
Published: November 2008

Background: Infectious pancreatic necrosis virus (IPNV) is a birnavirus that causes a lethal disease in both hatchery-reared juvenile salmonids and other non-salmonid fishes. IPNV has been classified into seven genogroups based on the analysis of the VP2/NS junction region of the viral A RNA segment. Methods: Ten organisms from two trout-rearing farms were used for viral isolation in RTG-2 cells. Cells were inoculated with samples from spleen, kidneys and pyloric caeca. The viral isolate was initially identified by electron microscopy, and confirmed by a commercial ELISA, RT-PCR and sequencing. A phylogenetic tree was constructed based on the deduced amino acids sequence of VP2. Results: An IPNV genogroup 1, labeled as EdoMex07, was isolated from a pool of renal tissues of five asymptomatic trout. The amino acid sequence analysis of VP2 showed that this IPNV presented the putative VP2 residue (221) already described in asymptomatic trout carriers. Conclusions: The EdoMex07 IPNV isolate belongs to genogroup 1, and has a VP2 phenotype which has been suggested to be involved in the establishment of the carrier state. This EdoMex07 IPNV is currently used as the standard positive control for detection of IPNV in rainbow trout farms in Mexico.
Effects of Interrupting Intravenous Saline Infusion on Sodium Excretion in the Dog
Authors: Buckalew, jr V.M. , Adkins T.G.
Published: November 2008

Systemic and renal hemodynamics, and plasma antinatriferic activity (AA) were measured before, during 2 h of saline loading, and for 1 h immediately after stopping saline infusion in dogs. During loading, mean arterial pressure (MAP), central venous pressure (CVP), renal blood flow (RBF), glomerular filtration rate (GFR), and AA increased as sodium excretion as (UNaV) rose progressively. During the post-loading period, MAP, CVP, and AA returned to baseline, RBF and GFR remained elevated, while UNaV fell. Only 52 ± 3% of the total sodium load was excreted during the study. These data show that AA is not regulated by the absolute volume of extracellular fluid. The correlation of AA with changes in systemic hemodynamics suggests ‘volume receptors’ in the resistance and/or capacitance circulation. The data suggest that the post-loading fall in UNaV is due at least in part to decreased levels of a humoral natriuretic factor.
The Effects of Varying Sodium Concentrations on the Metabolism of Glutamine by the Renal Cortex of the Rat
Authors: Hawthorn Janet , Alexander Jennifer A. , Alleyne George A.O.
Published: November 2008

We studied the effect of varying the sodium concentration on the tissue swelling and metabolism of renal cortical slices from control and acidotic rats. Lowering the sodium concentration in the incubation medium caused increased tissue swelling and depressed glutamine uptake, ammoniagenesis and gluconeogenesis in slices from both control and acidotic rats.
A Micropuncture Study of Glomerular Filtration and Tubular Reabsorption of Endogenous Renin in the Rat
Authors: Leyssac Paul P.
Published: November 2008

Renin concentrations in nanolitre samples of arterial and renal venous plasma and proximal tubular fluid were measured by radioimmunoassay. Clearance methods and occlusion- and transit time techniques were used for estimates of total renal and proximal tubular function. The renin concentration in proximal tubular fluid, when corrected for water reabsorption, declined exponentially along the convoluted segment. 90% of filtered renin was reabsorbed by this segment. The renin concentration of the ultrafiltrate was estimated to be 20% of the arterial plasma renin concentration. The loss of renin by glomerular filtration amounted to 5.4% of the amount carried to the afferent arteriole, and 16.4% of the net renin secretion rate.
Is There a PGE-Renin Feedback Control System in the Canine Kidney?
Authors: Selkurt Ewald E. , Hockel Gregory M. , Weinberger Myron H.
Published: November 2008

PGE1 infusion into the renal artery, after an initial stimulatory release of renin, is followed by a phase of declining renin release (RR), denoting a subsequent inhibition of this action. The later phase coincides with a rise in fractional clearance of electrolytes. This involves increased delivery of Na+, Ca2+, K+ and related anions from the proximal tubule, to the macula densa (MD) site, viewed as a sensor controlling the juxtaglomerular apparatus release of renin. The generally accepted action of these electrolytes here is inhibition of RR. In summary, PGE1 stimulation of RR could not be maintained despite continued infusion of the PG at a constant rate, and inferential data suggest a type of feedback inhibition of the MD.
Renin Secretion: Transient Response to a Step Reduction in Arterial Pressure
Authors: Mangelsen Eric L. , Malvin Richard L.
Published: November 2008

The transient response of renin secretion to a step reduction in arterial pressure (induced by clamping) was studied in the anesthetized dog. The kinetics of renin secretion were triphasic with an initial decrease, a rapid rise to a maximum and a subsequent decrease to one half this maximum. In a second series of experiments mannitol infusion maintained sodium excretion above control levels during arterial clamping; yet the transient response of renin secretion was essentially unchanged from the first series. These results suggest that renin secretion is predominantly under the control of a baroreceptor.
Effects of Isotonic Volume Expansion on Renal Nervous Activity and Renal Function in the Rat
Authors: Kottra Gábor , Albert Karola , Takács Lajos
Published: November 2008

The effects of isotonic volume expansion on efferent and afferent renal nervous activities and on some renal functional parameters were investigated in anaesthetized rats. Volume expansion resulted in a decrease of efferent neural traffic and in an increase of afferent activity. Water and sodium excretion were elevated without changes in the glomerular filtration rate. No quantitative correlation between the changes of sodium output and neural activity could be shown, and the increased central venous pressure did not seem to be the only determinant of the decreased efferent activity.
Sodium-Dependent and Sodium-Independent Glutamine Transport in the Control of Ammoniagenesis in Rat Kidney
Authors: McFarlane-Anderson Norma , Alleyne George A.O.
Published: November 2008

Our experiments show Na+-dependent and Na+-independent uptake of glutamine by renal cortical slices. In a Na+-containing buffer, sodium azide stimulates glutamine uptake and ammoniagenesis in slices from normal rats but has no effect on slices from acidotic rats. In Na+-free buffers azide does not alter ammoniagenesis or glutamine uptake by slices from normal rats but decrease both in slices from acidotic rats. Azide decreases ammoniagenesis in mitochondria from normal rats but increases it in mitochondria from acidotic rats. We conclude that azide stimulates Na+-dependent glutamine uptake and Na+-independent uptake may be stimulated by acidosis.
Phospholipase A2 in the Rat Kidney
Authors: Baggio B. , Favaro S. , Antonello A. , Bonn A. , Borsatti A.
Published: November 2008

The subcellular localization of phospholipase A2 – the key enzyme in prostaglandin biosynthesis – has been attempted in the rat kidney. By differential and sucrose gradient centrifugation the enzyme was almost completely recovered in the corpusculated fractions, thus suggesting a membrane localization. This was confirmed by the use of subcellular membranes. By gas chromatography it has been demonstrated that the enzyme splits off mainly arachidonic acid.
Aldosterone Effects on Renal Function in the Isolated Perfused Rat Kidney
Authors: Solomon Richard , Silva Patricio , Epstein Franklin H.
Published: November 2008

The excretion of potassium and the reabsorption of sodium were studied in isolated perfused kidneys of adrenalectomized rats following the administration of aldosterone. Aldosterone (10-7M) produced a rapid increase in fractional excretion of potassium, without affecting glomerular filtration rate, urine flow rate or sodium reabsorption. Spironolactone (10-4M) completely abolished the kaliuretic effect of aldosterone, while actinomycin D had no inhibitory effect. In the absence of exogenous metabolic substrate, enhancement of potassium excretion was not seen following aldosterone. With either glucose, pyruvate, lactate or α-ketoglutarate in the perfusion medium, the kaliuretic effect of aldosterone was restored. The results confirm the direct action of aldosterone on renal potassium excretion and its dependency upon the availability of specific metabolic substrates.
Dissociation of Sodium and Glucose Transport in the Isolated Perfused Rat Kidney: Effect of Lactate as a Substrate
Authors: Cambier P. , Godon J.P.
Published: November 2008

The influence of glucose and substrates on sodium transport (TNa) and glucose transport (Tg) was studied in isolated rat kidneys perfused according to Bowman’s technique. Glucose (0–8 g/l) was added to the perfusion fluid in the presence or absence of substrates: i.e. 2·10-3M pyruvate, 2·10-3M lactate, 5.10-3M glutamic acid and 1·10-3M oxaloacetic acid. When glucose was used at different concentrations in the perfusate, a correlation was found between Tg and TNa (p < 0.001); when substrates were added, lactate was found to be the only substrate able to improve TNa significantly without affecting Tg. Fractional sodium reabsorption reached 98.54% when lactate and glucose (2 g/l) were present in the perfusion medium. The data suggest the existence of a link between TNa and Tg and the possibility of some dissociation between them.
β-Amino Acid Transport in Isolated Tubule Segments
Authors: Friedman Aaron L. , Jax Diane K. , Chesney Russell W.
Published: November 2008

Using taurine as a model substrate, β-amino acid transport in isolated rat renal cortical tubule segments as studied. Heterogeneity of taurine accumulation was found in tubule segments and has previously been measured in renal cortex slices. In contrast to studies in cortical slices, initial rate kinetics could also be determined, and demonstrated uptake by two systems. Efflux of taurine from tubule cells was measured and showed 50% remaining in tubule segments after 30 min incubation in taurine-free medium. Concentrative uptake was prevented by NaCN and iodoacetate. Incubation with other β-amino acids resulted in decreased taurine accumulation. An important although unexpected finding was decreased taurine uptake by isolated tubules in the presence of Krebs-Ringer phosphate and Tris-HCl buffer as compared to Krebs-Ringer bicarbonate buffer. Isolated tubule preparations provide a rapid means of assessing β-amino acid transport including initial rate kinetics. However, when using tubules to study uptake, the buffer medium may play a critical role.
Prostaglandin Dependent and Independent Effects of Bradykinin on Renal Function in the Dog
Authors: Brouhard Ben H. , Gill, Jr. John R. , Yun John.C.H. , Kelly Gerald D. , Bartter Frederic C.
Published: November 2008

To determine the prostaglandin dependent and independent effects of bradykinin in the kidney, bradykinin (5.0 µg/min) was infused in the left renal artery during water diuresis in 17 hypophysectomized dogs, 9 control and 8 treated with indomethacin for 3 days before the study. In the control studies, bradykinin increased renin secretion (p < 0.02), cortical and non-cortical plasma flow (p < 0.05), and sodium and potassium excretion (p < 0.0005), without a change in glomerular filtration rate and with a decrease in distal fractional tubular reabsorption of chloride (p < 0.0025). In the studies with indomethacin, bradykinin increased renin secretion by 260 U/min, a significant (p < 0.02) response. Whereas cortical plasma flow did not change, non-cortical plasma flow, and sodium and potassium excretion increased and distal fractional tubular reabsorption of chloride decreased as in the control studies. Infusion of bradykinin at a lower dose of 0.5 µg/min did not change renin secretion or cortical plasma flow (p < 0.05), but increased non-cortical plasma flow and sodium excretion (p < 0.05). The results suggest that bradykinin increases cortical plasma flow by stimulation of prostaglandin synthesis, but increases renin secretion, non-cortical plasma flow and sodium and potassium excretion by an action which does not require the mediation of prostaglandins. An increase in renal plasma flow, which was a constant feature of renal arterial infusion of bradykinin, best explains the decrease in distal fractional chloride reabsorption and the increase in the excretion of sodium.
Effects of Various Diuretics and Dehydration on Superficial and Deep Nephron Renin Concentration in Rats
Authors: Nakamura Ryuichi , Saruta Takao , Nitta Seishi , Saito Ikuo , Hayashi Matsuhiko , Kondo Kazuoki , Kato Eiichi
Published: November 2008

In order to elucidate the mechanism of renin release by various diuretics, plasma renin activity (PRA) and single nephron renin concentration (SNRC) were determined after the administration of various diuretics. Administration of furosemide or thiazide increased PRA, superficial SNRC and urine volume significantly after 60 min. Potassium canrenoate did not modify urine volume, but it did increase PRA and superficial SNRC. It is possible, therefore, that each agent has a direct action on renin release by the juxtaglomerular cells in addition to a tubular diuretic effect.
Renal Handling of Urate by Nondiuretic and Diuretic Rats
Authors: Roch-Ramel Françoise , Granges Fabienne , Roth Liselotte , Widmer Janine , Weiner I.M.
Published: November 2008

Urate is reabsorbed throughout the accessible proximal tubule and, in nondiuretic animals, between the proximal and distal tubules. Proximal absorption of urate is diminished by volume expansion but not osmotic diuresis. The high performance liquid chromatographic method is satisfactory for estimation of urate in tubular samples.
Chronic Collection of Urine from the Unanesthetized Rabbit
Authors: Kluger Matthew J. , Turnbull Alastair J. , Cranston W.I. , Townsend Yvonne
Published: November 2008

A method for the chronic collection of urine from the unanesthetized rabbit is described. A midventral incision is made in the abdomen of an anesthetized rabbit, the urinary bladder exposed, and the end of a Malecot bladder catheter is inserted through a hole made in the bladder and is sewn in place. The free end of the catheter is run subcutaneously over the musculature of the back and neck and externalized inside the external pinna and then capped. To collect urine, the rabbit is placed in a standard rabbit stock, the catheter’s cap removed, a piece of tubing is connected to the exposed end of the catheter and a siphon formed. This permits the continuous collection of urine over several hours.