bluuebunny/crossref_metadata_2025 huggingface dataset:
Vegetation and climate of Auckland, New Zealand, since ca. 32 000 cal. yr ago: support for an extended LGM
Authors: Newnham Rewi M. , Lowe David J. , Giles Teresa , Alloway Brent V.
Published: June 2007

Auckland occupies a climatically sensitive position close to a major biogeographic boundary in the southern mid‐latitudes. A new pollen record from Kohuora maar crater, Auckland, displays vegetation and climatic changes for the past ca. 32 000 years. Of particular interest are the inferred climatic patterns for the first part of the interval, encompassing the Last Glacial Maximum (LGM). The Kohuora record corresponds closely with pollen records from other Auckland sites indicating that the patterns observed are at least regional in extent. It is also broadly consistent with a variety of palaeoenvironmental evidence from across New Zealand, including the glacial record from Westland, other palynological records from North Island, other palaeoecological records from the South Island, and aeolian quartz sequences from western North Island. These records show that glacial conditions prevailed across most, if not all, of New Zealand during the interval ca. 29–19 k cal. yr BP, longer and earlier than the LGM sensu stricto. We suggest that the term extended LGM (eLGM) may be more appropriate for the New Zealand region. Within this predominantly cold interval, the Auckland pollen records indicate a climatic amelioration for the interval ca. 26–24 k cal. yr BP, also consistent with other palaeocological data from Canterbury, that fall within a period of climate amelioration recognised between the first two eLGM glacial advances in Westland. We refer to this warming interval as the eLGM Interstadial. The ca. 27 k cal. yr BP Kawakawa/Oruanui tephra is instrumental in most of these inter‐site comparisons and occurs after the first peak of eLGM cooling in a short‐lived comparatively mild phase. A subsequent return to apparently colder climate in the Auckland records may indicate a volcanic cooling effect or, more likely, widespread landscape disturbance following this major eruption event. Strong correspondence between biotic responses, glacial fluctuations and aeolian quartz deposition linked to major shifts in strength and latitudinal extent of the southern westerlies suggest that both the eLGM and eLGM Interstadial may be more widely registered, at least across the Southern Ocean. Support for this assertion comes from parallel investigations in western and southernmost South America and isotopic and palaeoecological records from Southern Ocean marine cores. Recent reconstructions of the globally averaged ice‐equivalent sea‐level history are in line with this evidence from the Southern Hemisphere, suggesting that the eLGM may have a global registration. In light of these observations, we suggest a re‐examination of the defined timing of the LGM along with renewed effort to establish climatic patterns during this period and understand their causes. Copyright © 2007 John Wiley & Sons, Ltd.
Advanced Femtosecond Lasers for Industry and Science – Modern fs‐Lasers Are Sealed and Turn‐Key Systems
Authors: Renner Thomas , Lison Frank , Posthumus Jan
Published: June 2007

Femtosecond lasers belong to the most exciting kind of lasers. They are used in science, medicine and industry where their light serves for example as optical probe for time‐resolved studies, the analysis of biological material or the micro structuring of advanced material components.
High Power Diode Lasers for Industrial Applications
Authors: Horn Wolfgang
Published: June 2007

New wavelengths, high brightness and increasing reliability are breaking new ground for diode lasers. The higher brightness allows direct fiber coupling of several 100 W in 200 μm and 400 μm fibers and therefore i.e. the pumping of fiber lasers. Such high power fiber coupled laser diodes combined with fast beam deflection units (galvo scanners) have been implemented in industrial processes and used for quasi‐simultaneous welding of polymers, heat treatment in the sub millimeter range or selective soldering in solar cell production. Besides pumping of solid state lasers, high power diode lasers become more and more a competitive tool for many applications in material processing.
A Remark on Ascending Chain Conditions, the Countable Axiom of Choice and the Principle of Dependent Choices
Authors: Diener Karl‐Heinz
Published: June 2007

It is easy to prove in ZF− (= Zermelo‐Fraenkel set theory without the axioms of choice and foundation) that a relation R satisfies the maximal condition if and only if its transitive hull R* does; equivalently: R is well‐founded if and only if R* is. We will show in the following that, if the maximal condition is replaced by the (finite ascending) chain condition, as is often the case in Algebra, the resulting statement is not provable in ZF− anymore (if ZF− is consistent). More precisely, we will prove that this statement is equivalent in ZF− to the countable axiom of choice ACω. Moreover, applying this result we will prove that the axiom of dependent choices, restricted to partial orders as used in Algebra, already implies the general form for arbitrary relations as formulated first by Teichmüller and, independently, some time later by Bernays and Tarski.

Mathematics Subject Classification: 06B05, 08A65, 08B20, 03E99.
A Note on the Theorems of Church‐Turing and Trachtenbrot
Authors: Deutsch Michael
Published: June 2007

We sketch proofs of the theorems of Church‐Turing and Trachtenbrot using a semi‐monomorphic axiomatization.

Mathematics Subject Classification: 03B10, 03B25.
Cyclic Elements in MV‐Algebras and Post Algebras
Authors: Torrens Antoni
Published: June 2007

In this paper we characterize the MV‐algebras containing as subalgebras Post algebras of finitely many orders. For this we study cyclic elements in MV‐algebras which are the generators of the fundamental chain of the Post algebras.

Mathematics Subject Classification: 03G20, 03G25, 06D25, 06D30, 06F15, 06F35.
Hilbert's 17th Problem for Real Closed Rings
Authors: Mathews Larry
Published: June 2007

We recall the characterisation of positive definite polynomial functions over a real closed ring due to Dickmann, and give a new proof of this result, based upon ideas of Abraham Robinson. In addition we isolate the class of convexly ordered valuation rings for which this characterisation holds.

Mathematics Subject Classification: 03C60, 13L05, 12D15.
Recursively Enumerable Equivalence Relations Modulo Finite Differences
Authors: Nies André
Published: June 2007

We investigate the upper semilattice Eq* of recursively enumerable equivalence relations modulo finite differences. Several natural subclasses are shown to be first‐order definable in Eq*. Building on this we define a copy of the structure of recursively enumerable many‐one degrees in Eq*, thereby showing that Th(Eq*) has the same computational complexity as the true first‐order arithmetic.

Mathematics Subject Classification: 03D25, 03D15, 03D35.
Absolute Continuity and the Uniqueness of the Constructive Functional Calculus
Authors: Bridges Douglas , Ishihara Hajime
Published: June 2007

The constructive functional calculus for a sequence of commuting selfadjoint operators on a separable Hilbert space is shown to be independent of the orthonormal basis used in its construction. The proof requires a constructive criterion for the absolute continuity of two positive measures in terms of test functions.

Mathematics Subject Classification: 03F60, 46S30, 47S30.
A Note on Boolos' Proof of the Incompleteness Theorem
Authors: Kikuchi Makoto
Published: June 2007

We give a proof of Gödel's first incompleteness theorem based on Berry's paradox, and from it we also derive the second incompleteness theorem model‐theoretically.

Mathematics Subject Classification: 03F30.
The Axiom of Choice in Second‐Order Predicate Logic
Authors: Gaßner Christine
Published: June 2007

The present article deals with the power of the axiom of choice (AC) within the second‐order predicate logic. We investigate the relationship between several variants of AC and some other statements, known as equivalent to AC within the set theory of Zermelo and Fraenkel with atoms, in Henkin models of the one‐sorted second‐order predicate logic with identity without operation variables. The construction of models follows the ideas of Fraenkel and Mostowski. It is e. g. shown that the well‐ordering theorem for unary predicates is independent from AC for binary predicates and from the trichotomy law for unary predicates. Moreover, we show that the AC for binary predicates follows neither from the trichotomy law for unary predicates nor from Zorn's lemma for unary predicates nor from the formalization of the axiom of choice for disjoint families of sets for binary predicates, and that the trichotomy law for unary predicates does not follow from AC for binary predicates.

Mathematics Subject Classification: 03B15, 03E25, 04A25.
All Finitely Axiomatizable Normal Extensions of K4.3 are Decidable
Authors: Zakharyaschevm Michael , Alekseev Alexander
Published: June 2007

We use the apparatus of the canonical formulas introduced by Zakharyaschev [10] to prove that all finitely axiomatizable normal modal logics containing K4.3 are decidable, though possibly not characterized by classes of finite frames. Our method is purely frame‐theoretic. Roughly, given a normal logic L above K4.3, we enumerate effectively a class of (possibly infinite) frames with respect to which L is complete, show how to check effectively whether a frame in the class validates a given formula, and then apply a Harropstyle argument to establish the decidability of L, provided of course that it has finitely many axioms.
Temporal Algebras, Pretemporal Algebras, and Modal Algebras: A Relation between Time and Necessity
Authors: Olmedo Francisco M. García , Salas Antonio J. Rodríguez
Published: June 2007

In this paper the structure of pretemporal algebra is used to study some aspects of temporal algebras and modal algebras. The paper contains a computational approach to finite temporal algebras and a general splitting theorem for finite temporal algebras.
Non Standard Regular Finite Set Theory
Authors: Baratella Stefano , Ferro Ruggero
Published: June 2007

We propose a set theory, called NRFST, in which the Cantorian axiom of infinity is negated, and a new notion of infinity is introduced via non standard methods, i. e. via adequate notions of standard and internal, two unary predicates added to the language of ZF. After some initial results on NRFST, we investigate its relative consistency with respect to ZF and Kawai's WNST.
Binary Relations and Permutation Groups
Authors: Andréka Hajnal , Düntsch Ivo
Published: June 2007

We discuss some new properties of the natural Galois connection among set relation algebras, permutation groups, and first order logic. In particular, we exhibit infinitely many permutational relation algebras without a Galois closed representation, and we also show that every relation algebra on a set with at most six elements is Galois closed and essentially unique. Thus, we obtain the surprising result that on such sets, logic with three variables is as powerful in expression as full first order logic.
Well‐Defined Fuzzy Sentential Logic
Authors: Turunen Esko
Published: June 2007

A many‐valued sentential logic with truth values in an injective MV‐algebra is introduced and the axiomatizability of this logic is proved. The paper develops some ideas of Goguen and generalizes the results of Pavelka on the unit interval. The proof for completeness is purely algebraic. A corollary of the Completeness Theorem is that fuzzy logic on the unit interval is semantically complete if and only if the algebra of the truth values is a complete MV‐algebra. In the well‐defined fuzzy sentential logic holds the Compactness Theorem, while the Deduction Theorem and the Finiteness Theorem in general do not hold. Because of its generality and good‐behaviour, MV‐valued logic can be regarded as a mathematical basis of fuzzy reasoning.
The Set of Better Quasi Orderings is ∏
Authors: Marcone Alberto
Published: June 2007

In this paper we give a proof of the II12‐completeness of the set of countable better quasi orderings (viewed as a subset of the Cantor space). This result was conjectured by Clote in [2] and proved by the author in his Ph.d. thesis [6] (see also [7]). Here we prove it using Simpson's definition of better quasi ordering ([15]) and as little bqo theory as possible.
Some New Lattice Constructions in High R. E. Degrees
Authors: Rolletschek Heinrich
Published: June 2007

A well‐known theorem by Martin asserts that the degrees of maximal sets are precisely the high recursively enumerable (r. e.) degrees, and the same is true with ‘maximal’ replaced by ‘dense simple’, ‘r‐maximal’, ‘strongly hypersimple’ or ‘finitely strongly hypersimple’. Many other constructions can also be carried out in any given high r. e. degree, for instance r‐maximal or hyperhypersimple sets without maximal supersets (Lerman, Lachlan). In this paper questions of this type are considered systematically. Ultimately it is shown that every conjunction of simplicity‐ and non‐extensibility properties can be accomplished, unless it is ruled out by well‐known, elementary results. Moreover, each construction can be carried out in any given high r. e. degree, as might be expected. For instance, every high r. e. degree contains a dense simple, strongly hypersimple set A which is contained neither in a hyperhypersimple nor in an r‐maximal set. The paper also contains some auxiliary results, for instance: every r. e. set B can be transformed into an r. e. set A such that (i) A has no dense simple superset, (ii) the transformation preserves simplicity‐ or non‐extensibility properties as far as this is consistent with (i), and (iii) A T B if B is high, and A ≥T B otherwise. Several proofs involve refinements of known constructions; relationships to earlier results are discussed in detail.
Constants in Kripke Models for Intuitionistic Logic
Authors: Dzierzgowski Daniel
Published: June 2007

We present a technique to extend a Kripke structure (for intuitionistic logic) into an elementary extension satisfying some property (cardinality, saturation, etc.) which can be “axiomatized” by a family of sets of sentences, where, most often, many constant symbols occur. To that end, we prove extended theorems of completeness and compactness. Also, a section of the paper is devoted to the back‐and‐forth construction of isomorphisms between Kripke structures.
Non‐associative Lambek Categorial Grammar in Polynomial Time
Authors: Aarts Erik , Trautwein Kees
Published: June 2007

We present a new axiomatization of the non‐associative Lambek calculus. We prove that it takes polynomial time to reduce any non‐associative Lambek categorial grammar to an equivalent context‐free grammar. Since it is possible to recognize a sentence generated by a context‐free grammar in polynomial time, this proves that a sentence generated by any non‐associative Lambek categorial grammar can be recognized in polynomial time.
A General Type for Storage Operators
Authors: Nour Karim
Published: June 2007

In 1990, J. L. Krivine introduced the notion of storage operator to simulate, in λ‐calculus, the “call by value” in a context of a “call by name”. J. L. Krivine has showed that, using Gödel translation from classical to intuitionistic logic, we can find a simple type for storage operators in AF2 type system. In the present paper we give a general type for storage operators in a slight extension of AF2. At the end we give (without proof) a generalization of this result to other types.
Intuitionistic ϵ‐ and τ‐calculi
Authors: Devidi David
Published: June 2007

There are several open problems in the study of the calculi which result from adding either of Hilbert's ϵ‐ or τ‐operators to the first order intuitionistic predicate calculus. This paper provides answers to several of them. In particular, the first complete and sound semantics for these calculi are presented, in both a “quasi‐extensional” version which uses choice functions in a straightforward way to interpret the ϵ‐ or τ‐terms, and in a form which does not require extensionality assumptions. Unlike the classical case, the addition of either operator to intuitionistic logic is non‐conservative. Several interesting consequences of the addition of each operator are proved. Finally, the independence of several other schemes in either calculus are also proved, making use of the semantics supplied earlier in the paper.
Microeconomic foundations of corporate strategy
Authors: Naylor Thomas H. , Thomas Celia
Published: June 2007

This paper examines several approaches to corporate strategic planning in the context of their relationship to the microeconomic theory of the firm, and discusses the implications of that theory for corporate strategy in general. Specifically, three types of analytical tools are discussed: (1) analytical portfolio models; (2) business simulation models; and (3) optimization models. Examples of how the three types of tools are used in corporate decision‐making are given, and certain limitations are cited. The limitations include, for example, the inability of some of the models to deal with interdependencies across business units in production resources or output demand. Finally, the paper examines the approach to strategic planning known as the ‘strategy matrix’, which explicitly allows for interdependices across business units. The use of the strategy matrix by a major petroleum company is discussed in some detail.
Industrial organization and the evolution of concepts for strategic planning: The new learning
Authors: Porter Michael E.
Published: June 2007

This paper reviews the parallel development of the disciplines of corporate strategy and industrial organisation. Recent developments in industrial economics suggest that the two may be about to merge, or at least be capable of synergy. This potential advance has come about because of the movement of industrial organisation theories towards dynamics and away from static concepts such as the traditional structure: conduct: performance model. Simultaneously, corporate strategists, who have always been dynamically oriented, have long been in search of the more sophisticated theories industrial economists have in their tool kits.
Foreign location decisions by US transnational firms: An empirical study
Authors: Hollander Abraham
Published: June 2007

The paper aims at identifying the variables that are significant in determining the choice of host countries for manufacturing subsidiaries of US transnational firms. The approach that is taken is to relate variables that on the basis on a priori theoretical reasoning influence foreign location decisions, with (a) total market penetration by US firms and (b) the choice these firms make between exporting to their foreign markets and on site manufacturing. Location decisions are viewed as emerging from the interaction of characteristics typical to the industry of the transnational firm and factors specific to potential host countries. Particular attention is devoted to finding out whether locational choices and market shares are interdependent. The sample of observations under investigation consists of the activities of US majority‐owned subsidiaries, classified in fourteen industry groupings and operating twenty countries. Sub‐samples of countries are also studied. It is found that for the European countries, in particular EEC members, market penetration is dependent on local manufacturing.
Some refinements in austrian trade‐cycle theory
Authors: Wood J. Stuart
Published: June 2007

Changes in the apparent rate of interest have different effects upon different types of firms, causing the onset of the business cycle to be initiated in specialty suppliers to high‐order capital goods manufacturers. These specialty manufacturers utilize bank loans to finance inventories, so they are sensitive to changes in market rates, while consumer‐goods manufacturers finance capital projects using long‐term sources of funds, which are less sensitive. The abandonment of capital projects by lower‐order manufacturers is also less sensitive to interest rate movements than the manufacturing operations of the high‐order suppliers.
Structure and performance of US wholesale trade
Authors: Martin Stephen
Published: June 2007

Using an industry‐level sample, the author examines the extent to which wholesale trade is carried out by vertically integrated as opposed to non‐integrated distributors. Using this sample and a sample of divisions of manufacturing firms, he tests the impact of industry structure, group structure within industry and firm structure on performance at the wholesale level.
Technological change in health care: Why are opinions so divided?
Authors: Zweifel Peter
Published: June 2007

This paper purports to explain the widespread scepticism towards technological change in health care in general and pharmaceutical innovation in particular in the face of very high estimated rates of social return. These estimates are based on observable market prices and quantities, which are used for measuring the additional consumer surplus induced by an innovation. They grossly overstate true surplus due to the effect of insurance, however. For true demand for health care services and hence true surplus depends on the net price a patient is willing to pay, which is a rather small fraction of observed market price. The paper also outlines the conditions under which a health insurer would welcome a pharmaceutical innovation.
Concentration change and the structure—performance debate: An interpretive essay
Authors: Carter John R.
Published: June 2007

It is demonstrated that the hypotheses and tests found in the concentration change literature fail to discriminate adequately among the competing theories. This failure is characteristic of the larger structure‐performance debate, raising the question of whether there is something in the nature of the debate which permits it to persist but never really progress. It is argued that the debate is derived in large part from differences which on one level are purely semantic but which on a deeper level concern the normative bases up on which market outcomes are interpreted. If a meaningful resolution is to be hoped for, it must be sought at much deeper levels of inquiry.
A study of measuring influence of advertising and forecasting cigarette sales
Authors: Yucelt Ugur , Kaynak Erdener
Published: June 2007

This study investigated the effect of advertising on cigarette sales, particularly after 1967. Data were collected using sources of the Statistical abstract of the U.S., the Historical Statistics of the U.S. and Vital Statistics between 1955 and 1979. A multiple regression model was used to analyze the data. Cigarette consumption was used as a dependent variable. Disposable Income, Death Rate due to cancer of the respiratory system/total cancer death, advertising outlays for cigarettes: Newspapers and television advertisement/total advertising cost, cigarette‐production (including long and regular sizes), sales outlets, loyalty/total loyalty, average price for cigarettes and a dummy variable were used as independent variables. Analysis revealed that there is a significant negative relationship between cigarette‐consumption and total cancer death and average prices on the one hand, and a significant positive association between loyalty and cigarette consumption on the other. Although advertising expenditures are not statistically significant, increased spending on advertising has an increasing effect on cigarette‐consumption.
Advertising expenditure and aggregate consumption in Britain and West Germany: An analysis of causality
Authors: Sturgess Brian T. , Wilson Nicholas
Published: June 2007

This paper surveys past work which attempts to investigate the effects of advertising on the macro‐economy, in particular on the allocation of income to consumption expenditure. It is argued that many prior studies aimed at testing this ‘Galbraithian’ hypothesis have suffered from an inability to detect the direction of any causal flows and may have only detected spurious relationships. Here, the relationship is analysed for West Germany and Great Britain, with the use of bivariate time series modelling techniques considered initially by Granger and Newbold. The advantages and disadvantages of using the concept of ‘Granger Causation’ are considered in relation to testing this area of interest. No support is found for the proposition that advertising has a positive causal effect on aggregate consumption in the two countries.
A note on capital budgeting in the purchase of information
Authors: Mehrez Abraham , Stulman Alan
Published: June 2007

A capital budgeting problem of purchasing perfect information is defined. The relationship between this problem and the Expected Value measure is shown and an illustrative example provided.
Organizational capital and the choice between specialization and diversification
Authors: Gort Michael , Grabowski Henry , McGuckin Robert
Published: June 2007

This paper specifies a model in which the preservation of organizational capital is the principal factor motivating corporate diversification decisions. Alternative hypotheses of the determinants of diversification are then subjected to empirical test with data for 96 US industrial firms in the 1967–71 period. Consistent with the model, variables associated with unfavorable expectations on the marginal returns to investment in existing activities proved dominant in explaining ‘desired’ increases in diversification. Alternative explanations, namely, the role of managerial attributes, of absolute advantages of some firms, and of opportunities created by research and development, had more modest explanatory power.
Learning by a dominant firm
Authors: Harpaz Giora
Published: June 2007

This paper is concerned with the optimal output decisions of a dominant firm in the presence of imperfect information about the rival's reactions. The model is multi‐period with the profits in each period being independent of those in other periods. Consequently, if the rival's reaction parameter were known to the dominant firm, a myopic policy would be optimal, In the presence of imperfect information about the rival's unknown reaction parameter, the dominant firm acts in a Bayesian manner by updating its prior distribution based on the observations of the rival's outputs. Because of the multiplicative shape of the rival's reaction function, the Bayesian updating rule is a function of the dominant firm's decision variable, i.e. its output decisions. This creates a dependence of the future value of the dominant firm on the present output decision, and hence a myopic policy is not, in general, optimal. It is shown that through output experimentation the dominant firm will tend to overproduce and, consequently, will increase its expected discounted profits (market value).
Security‐holder cash flows and the valuation of corporate investment projects
Authors: Lewellen Wilbur G. , Emery Douglas R.
Published: June 2007

The difference between adjusted present value and cost‐of‐capital discounting procedures for evaluating corporate real‐asset investment projects is re‐examined. The two approaches are shown to contain different implicit assumptions about the distribution of project cash flows to security‐holders. The consequences thereof for the proper valuation of individual projects in the context of a multiproject investment plan are considered.
The organization and relative productivity of Japanese and American industry
Authors: Comanor William S. , Miyao Takahiro
Published: June 2007

This paper compares the structure and productivity of Japanese and American firms. We construct a simple model of labor shares in which the ratio of labor payments to sales is the product of labor's share in take added and the degree of integration. According to Japanese and United States census data, labor shares in value added are fairly similar for Japanese and American firms, whereas the average degree of integration, and therefore the average ratio of payroll to sales of Japanese firms, is distinctly lower than that of their American counterparts, particularly in the machinery and equipment industries.

From survey data on Japanese firms in California, we observed payroll‐sales ratios that generally lie between values reported for Japan and the United Slates for the machinery and equipment industries. Assuming that Japanese firms in California employ the same technology as their US counterparts, we conclude that the average degree of integration of Japanese firms in California is at least 10% lower. As a result, even though the gross labor productivity of typical Japanese firms in the United States generally, and California in particular, is slightly higher, the former may well be less productive than the latter in terms of net lalmr productivity, measured by value added.

While further corroboration is needed, it appears that differences in the extent of integration are an important factor that accounts for reported productivity difference between the two countries.
Generic substitution in the UK pharmaceutical industry: A markovian analysis
Authors: Reekie W. Duncan , Allen D. E.
Published: June 2007

This paper examines the impact of competition on product market shares in the UK pharmaceutical industry. The topic is of particular interest since, although it is well known that such products are already subject to competition by innovation and by price (Cooper, 1966, Ch. 3; Reekie, 1978), the possible introduction in the UK of generic substitution (Greenfield, 1982, p. 24), could further increase competitive pressures. Our aim is to apply Markov probabilistic analysis to existing market data. This will enable us (after Adelman, 1958) to analyse the structure which the industry will ‘eventually reach if certain current trends were to continue’ (Adelman, p. 893). In particular, we apply the technique to sub‐samples of the data, to infer how the competitive process influences the industry's configuration when generic competition is present. The outcome can be used as a conservative indicator of the impact on the industry if generic substitution was to be adopted in the National Health Service (NHS).

The plan of the paper is as follows. In the first section a brief resumt of the debate which has surrounded generic substitution proposals is presented. The second section details the data and sample used in our empirical work. The third section applies Markov chain analysis to that data and reports our results. The final section summarizes our conclusions and discusses some of the problems and limitations of our results.
On the probability of entry in potential competition cases
Authors: Horowftz Ira
Published: June 2007

This paper explores, both theoretically and empirically, the extent to which having ‘other potential entrants’ to a market injected into potential‐competition cases has been a worthwhile enterprise. This two‐pronged attack leads to the conclusion that (he attempt to specifically identify potential entrants probably results in our deluding ourselves as to the likelihood that entry will occur, and that unless a convincing argument can be made to the effect that any given potential entrant from a stockpile of unnamed potential entrants is ‘reasonably likely’ to elect the entry option, expanding lhat stockpile will be similarly misleading.
Lysosomal hydrolases in cerebrospinal fluid from subjects with Parkinson's disease
Authors: Balducci Chiara , Pierguidi Laura , Persichetti Emanuele , Parnetti Lucilla , Sbaragli Michele , Tassi Carmelo , Orlacchio Aldo , Calabresi Paolo , Beccari Tommaso , Rossi Aroldo
Published: June 2007

Recent studies have shown a genetic association between glucocerebrosidase deficiencies and Parkinson's disease (PD). To further explore this issue the activity of β‐glucocerebrosidase and the activities of other lysosomal enzymes, α‐mannosidase, β‐mannosidase, β‐hexosaminidase, and β‐galactosidase have been evaluated in the cerebrospinal fluid (CSF) of PD patients. The activities of α‐mannosidase, β‐mannosidase, β‐glucocerebrosidase, and β‐hexosaminidase were substantially decreased in the CSF of PD patients, while levels of β‐galactosidase were essentially identical to controls. This study indicates that in PD several lysosomal hydrolases have decreased activities, further supporting a possible link between pathophysiological mechanisms underlying PD and lysosomal hydrolases. © 2007 Movement Disorder Society
Patient‐reported outcome II: selecting appropriate measures for musculoskeletal care
Authors: Haywood Kirstie L
Published: June 2007

The first article in this series outlined the important contribution that well developed patient reported outcome measures (PROMs) can make to healthcare, clinical decision making and evaluation. The increasing focus on patient reported health means that there are now hundreds of questionnaires available; selecting the appropriate measure is both challenging and essential. This article will introduce potential users of PROMs to key information to consider when selecting and using PROMs in research, routine practice or quality assurance. Important concepts, such as measurement reliability, validity and responsiveness to important change in health, will be explored and illustrated with examples from musculoskeletal healthcare. Practical properties, such as acceptability and feasibility, will also be introduced. Copyright © 2007 John Wiley & Sons, Ltd.
Characterization of brain metastases using high‐resolution magic angle spinning MRS
Authors: E. Sjøbakk Torill , Johansen Roar , Bathen Tone F. , Sonnewald Ursula , Juul Roar , Torp Sverre H. , Lundgren Steinar , Gribbestad Ingrid S.
Published: June 2007

The objectives of this study were to (a) explore the spectral characteristics of brain metastases, focusing on the origin of the primary cancer, and (b) evaluate the correlation with clinical outcome using multivariate analysis. High‐resolution magic angle spinning (HR‐MAS) MR spectra (n = 26) were obtained from 16 patients with brain metastases using a Bruker Avance DRX600 instrument. Standard pulse‐acquired and spin‐echo (TE 32 and 285 ms) 1H spectra were obtained. These were examined using principal component analysis (PCA) and partial least squares regression analysis (PLS) relating spectral data to clinical outcome. The PCA score plot of pulse‐acquired HR‐MAS spectra showed a trend of clustering due to the origin of the metastases, mainly based on differences in the lipid signals at 1.3 and 0.9 ppm. With PLS, spectra of patients who died less than 5 months after surgery appeared to cluster in the lower left quadrant of the score plot. These preliminary results on brain metastasis classification and prediction of survival must be validated in a larger patient cohort. However, the possibility of differentiating metastases according to origin and predicting survival on the basis of HR‐MAS spectra suggests that this method may be useful for diagnosing and planning treatment for brain metastases and also for guiding decisions about terminating further treatment. Copyright © 2007 John Wiley & Sons, Ltd.
Synthesis and properties of polyimides derived from 1,4‐bis(4‐aminophenoxy)‐2‐(6‐oxido‐6H‐dibenz[c,e] [1,2]oxaphosphorin‐6‐yl) phenylene
Authors: Lin Ching Hsuan , Lin Chun Hung
Published: June 2007

A new phosphorus‐containing aromatic diamine, 1,4‐bis(4‐aminophenoxy)‐2‐(6‐oxido‐6H‐dibenz[c,e] [1,2]oxaphosphorin‐6‐yl) phenylene (3) was synthesized by the nucleophilic aromatic substitution of 2‐(6‐oxido‐6H‐dibenz[c,e] [1,2]oxaphosphorin‐6‐yl)‐1,4‐dihydroxy phenylene (1) with 4‐fluoronitrobenzene, followed by catalytic hydrogenation. Light color, flexible, and creasable polyimides with high molecular weight, high glass transition, high thermal stability, improved organosolubility, and good oxygen plasma resistance were synthesized from the condensation of (3) with various aromatic dianhydrides in N,N‐dimethylacetamide, followed by thermal imidization. The number‐average molecular weights of polyimides are in the range of 7.0–8.3 × 104 g/mol, and the weight‐average molecular weights are in the range of 12.5–16.5 × 104 g/mol. The Tgs of these polyimides range from 230 to 304 °C by differential scanning calorimetry and from 228 to 305 °C by DMA. These polyimides are tough and flexible, with tensile strength at around 100 MPa. The degradation temperatures (Td 5%) and char yields at 800 °C in nitrogen range from 544 to 597 °C and 59–65 wt %, respectively. Polyimides 5c and 5e, derived from OPDA and 6FDA, respectively, with the cutoff wavelength of 347 and 342 μm, respectively, show very light color. These polyimides also exhibit good oxygen plasma resistance. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2897–2912, 2007
Public safety aspects of pyrethroid insecticides used in West Nile virus‐carrying mosquito control
Authors: Gammon Derek W
Published: June 2007

West Nile virus is becoming increasingly prevalent in the USA, causing fever, encephalitis, meningitis and many fatalities. Spread of the disease is reduced by controlling the mosquito vectors by a variety of means, including the use of pyrethroid insecticides, which are currently under scrutiny for potential carcinogenic effects in humans. Pyrethrins and resmethrin, a pyrethroid, have been shown to cause tumours in rat and mouse models respectively. However, the tumours appear to be caused by liver enzyme induction and hypertrophy rather than genotoxicity, and the results are therefore unlikely to be applicable to humans. Nonetheless, for resmethrin, the US Environmental Protection Agency (EPA) has concluded that there is a likely risk of carcinogenicity in humans, requiring the manufacturers to provide more detailed data to prove that it can be used safely in vector control. Reproductive toxicity of resmethrin in the rat is also discussed. Copyright © 2007 Society of Chemical Industry
Pressure‐ and temperature‐induced structural changes in simulated amorphous Al2O3·2SiO2
Authors: Van Hoang Vo , Linh Nguyen Ngoc , Hung Nguyen Hoang
Published: June 2007

We investigated the pressure‐ and temperature‐induced structural changes in amorphous Al2O3·2SiO2 by a molecular dynamics method. Simulations were done in a basic cube under periodic boundary conditions containing 3025 ions with the Born–Mayer type pair potentials. In order to study the structural changes, nine models of amorphous Al2O3·2SiO2 at 350 K and at densities ranging from 2.6 g/cm–3 to 4.2 g/cm–3 have been built. The microstructure of the amorphous Al2O3·2SiO2 has been analyzed through the pair radial distribution functions, coordination number, bond‐angle distributions, and interatomic distances. Moreover, we found clear evidence of structural changes from a tetrahedral to an octahedral network structure in the system upon compression. We also found that the changes reverse from an octahedral to a tetrahedral network structure by subsequent heating of an octahedral structure model from 350 K to 1610 K at constant external pressure P = 0 GPa. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of temperature on elastic properties of caesium cyanide
Authors: Singh Preeti , Gaur N. K. , Singh R. K.
Published: June 2007

An extended three body force shell model (ETSM), which incorporates the effects of translational–rotational (TR) coupling, three body interactions (TBI) and anharmonicity, has been applied to investigate the temperature dependence of the second order elastic constants (cij, i, j = 1, 2) of CsCN. The elastic constant c44 obtained by us shows an anomalous behaviour with the variation of temperature. The variations of elastic constants (c11, c12, c44) with temperature are almost in excellent agreement with Brillouin scattering measured data. We have also evaluated the temperature variations of the third order elastic constants (cijk) and the pressure derivatives of the cij in the CsCN material. However, their values could not be compared due to lack of experimental data. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical investigation of intersubband nonlinear optical rectification in Alx lGa1–xlAs/GaAs/Alx rGa1–xrAs asymmetric rectangular quantum wells
Authors: Karabulut İbrahim , Atav Ülfet , Şafak Haluk , Tomak Mehmet
Published: June 2007

In this study, a theoretical investigation of intersubband nonlinear optical rectification in Alx lGa1–x lAs/ GaAs/Alx rGa1–x rAs asymmetric rectangular quantum wells is presented. The electronic states in the asymmetric rectangular quantum well are described within the framework of the envelope function approach including the effects of band nonparabolicity and the effective mass mismatch. The nonlinear optical rectification is calculated using the density matrix formalism. It is found that the nonlinear optical rectification in the asymmetric rectangular quantum well depends sensitively on the parameters such as the width and the asymmetry of the potential well. The adjustable parameters allow for tuning of the asymmetric rectangular quantum well system to the desired wavelength while retaining a large optical rectification coefficient. This gives a new degree of freedom in various device applications based on nonlinear optical properties. Band nonparabolicity is found to significantly influence both electronic states and nonlinear optical rectification. Moreover the resulting optical rectification coefficient is much larger than the ones for bulk GaAs and some other theoretical studies in literature. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Is the smallest carbon nanotube (2,2) a metal or a semiconductor?
Authors: Scipioni R.
Published: June 2007

We perform a first principles study of the smallest carbon nanotube ever discovered namely the (2,2) tube with diameter 0.27 nm. Contrary to what recently stated in the literature, the curvature effects are not enough to convert the (2,2) nanotube into a semiconductor and the (2,2) nanotube is metallic in agreement with the simple folding model of graphite. However, as a result of the distortion, the band structure is only converged if a full relaxation and a fine mesh of K points are used to sample the Brillouin zone. We then consider the (2,2) tube in the DWNT (7,7)–(13,13). This system is also found to be metallic. We infer that the recently observed (2,2)@MWNT is a metallic material. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Eta‐pairing and s‐wave pairing in the Penson–Kolb model with next‐nearest neighbour hopping
Authors: Czart W. R. , Robaszkiewicz S. , Tobijaszewska B.
Published: June 2007

We study the two‐dimensional Penson–Kolb model, i.e the tight‐binding model with the pair‐hopping interaction J, and analyze the effects of next‐nearest neighbour hopping t2 on the superconductivity in this system. In the analysis we focus on the properties of the superconducting state with Cooper‐pair center‐of‐mass momentum q = Q (eta‐phase), which can develop in this model for the case of repulsive J (J < 0) and q = 0 (s‐wave phase), which develops for the case of attractive J (J > 0). The evolutions of the phase diagrams, ground state characteristics and the transition temperatures with particle concentration and pairing strength are determined for square lattice. Within the Kosterlitz–Thouless scenario the Uemura‐type plots (Tc vs. 1/λ2(0)) are also derived. The results for t2 ≠ 0 are compared with those found for the case with nn hopping only. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Luminescence of K1–xRbx CaF3 upon the outermost 3p K+ and 4p Rb+ core ionization
Authors: Stryganyuk G. B. , Chornodolskyy Ya. M. , Voloshinovskii A. S. , Ivanov M. P. , Vasylechko L. O.
Published: June 2007

The luminescence and reflection spectra of K1–x Rbx CaF3 crystals have been studied using synchrotron radiation. Luminescence of self‐trapped exciton and core‐valence luminescence are revealed for KCaF3 crystals in UV and VUV spectral range, respectively. The core‐valence VUV luminescence of KCaF3 appears after 3p K+ core ionization and originates from the radiative recombination of 3p K2+ core holes with 2p F– valence electrons. The fast UV luminescence of K1–x Rbx CaF3 crystals has been attributed to the radiative recombination of the holes in 4p Rb2+ impurity core states with 2p F– valence electrons. The impurity core‐valence luminescence of K1–x Rbx CaF3 reveals the excitation threshold corresponding to the ionization of impurity 4p Rb+ core states. Efficient excitation of 4p Rb+ related luminescence of K1–x Rbx CaF3 within the energy range of 3p K+ core ionization is considered as an evidence for the hole migration from the host 3p K+ core band to the impurity 4p Rb+ core states. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of buffer‐related lag phenomena and current collapse in GaN FETs
Authors: Itagaki K. , Kobayashi N. , Horio K.
Published: June 2007

Drain‐current responses of GaN MESFETs with a semi‐insulating buffer layer are calculated when the drain voltage and/or the gate voltage are changed abruptly, and pulsed I‐V curves are derived from them. It is shown that so‐called current collapse or current slump is not so dependent on the gate length LG (0.3 μm – 1 μm), and this is essentially determined by a deep‐acceptor density NDA in the buffer layer. LG and NDA dependence of gate lag is also studied, indicating that the gate lag is weaker for longer LG and the lag rate becomes high with NDA, although it may show a saturation behaviour. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phonon dispersion in GaN/AlN non‐polar quantum wells: confinement and anisotropy
Authors: Cros A. , Pomer F.
Published: June 2007

We have calculated the phonon dispersion relations in a non‐polar GaN/AlN quantum well within the dielectric continuum model and making use of Loudon's model of uniaxial crystals. Due to the strong in‐plane anisotropy of this orientation, we have found that in general ordinary and extraordinary phonons are not decoupled. In this work we analyze the conditions for the occurrence of interface modes. In these novel heterostructures there is an added dependence of the phonon dispersion on the orientation of the in‐plane phonon wavevector, which allows the existence of interface phonons at energies forbidden in the better known polar structures. Under particular circumstances the vibrations excited in the wurtzite heterostructure have the characteristics of those found in cubic crystals. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Material and optical properties of Trenched Epitaxial Lateral Overgrowth of a‐plane GaN
Authors: Wang Te‐Chung , Lu Tien‐Chang , Ko Tsung‐Shine , Kuo Hao‐Chung , Chen Hou‐Guang , Yu Min , Chuo Chang‐Cheng , Lee Zheng‐Hong , Wang Sing‐Chung
Published: June 2007

The crystal quality of a‐plane GaN film was successfully improved by using trenched epitaxial lateral overgrowth (TELOG) of a‐plane GaN. Not only the threading dislocation density but also the difference of anisotropic in‐plane strain between orthogonal crystal axes can be mitigated by using TELOG. The low threading dislocation density investigated by transmission electron microscopy was estimated to be 3×107 cm–2 on the N‐face GaN wing. According the results of μ‐PL and CL, the threading dislocations are the strongly non‐radiative center in a‐plane GaN film. Finally, we concluded that a narrower stripped GaN seeds and deeper stripped trenches etched into the surface of sapphire could derive a better quality a‐plane GaN film. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Wide spectral responses InxGa1–xN deep UV photomultiplier tube
Authors: Uchiyama Shoichi , Takagi Yasufumi , Kondoh Haruyasu , Takatsuka Hiroyuki , Suzuki Hideaki , Ohishi Yasuo , Suzuki Nobuharu , Okano Kazuyoshi , Niigaki Minoru , Kan Hirofumi
Published: June 2007

We have designed and fabricated new photo‐tubes and photomultiplier tubes (PMTs) using InxGa1‐xN films as photocathodes. Longer spectral cutoffs were controlled with Indium compositions x, from 365 nm to 430 nm. The calibrated maximum quantum efficiency (QE) of 56% at 200 nm was achieved for x = 0.11 Indium composition in the photo‐tubes. Sharp cutoffs at around 160 nms were determined by window materials and those at around 400 nms were determined by the band gaps of the photocathodes. Gain and input/output linearity properties were confirmed to be very good for the PMTs. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)