bluuebunny/crossref_metadata_2025 huggingface dataset:
Prenatal laser treatment of a placental chorioangioma
Authors: Quarello E. , Bernard J.‐P. , Leroy B. , Ville Y.
Published: February 2005

Large placental chorioangiomas are rare complications in pregnancy. We present a case of a placental chorioangioma, complicated by polyhydramnios, in which obliteration of its blood supply using diode laser coagulation at 25 weeks of gestation was followed by an uneventful pregnancy and delivery of a healthy baby with a normal follow‐up at the age of 9 months. Laser coagulation of the feeding vessels seems to be an effective treatment for chorioangiomas when the blood supply is superficial and the feeding vessels are small in diameter. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.
Identification of albumin-binding proteins of thymocyte plasmalemma
Authors: Dorbrila Ludy , Serban Geo , Heltianu Constantina
Published: February 2005

In the present work we examined whether the interaction between albumin molecules and thymocytes involves albumin-binding proteins (ABP). Two plasmalemma-rich fractions obtained by differential centrifugation from rat thymus lymphocytes were characterized biochemically and morphologically. These fractions were examined by ligand-blotting and ligand affinity chromatography techniques. Plasmalemma proteins separated by SDS-PAGE were electrotransferred onto nitrocellulose membranes and incubated with125I-albumin, in the presence or absence of excess native albumin. The autoradiogram revealed specific binding to two sets of polypeptides of 16–18 and 29–31 kDa, which could be blocked by native albumin. To elucidate whether albumin-binding proteins are exposed on the cell surface, intact lymphocytes were surface radioiodinated and membrane fractions prepared from them were subjected to affinity chromatography on albumin-agarose beads. The proteins thus purified had, like ABP, Mr of 16 and 31. These data indicate that ABP (i) are components of thymocyte plasma membrane, (ii) have apparent molecular mass of 16–18 and 29–31 kDa, and (iii) are exposed on the outer membrane surface.
The human connexin32 gene is transcribed from two tissue-specific promoters
Authors: Neuhaus Isaac M. , Bone Linda , Wang Suping , Ionasescu Victor , Werner Rudolf
Published: February 2005

The connexin32 (cx32) gene codes for the gap junction protein found in liver, pancreas and nervous tissue. Recently mutations in the coding region of this gene have been associated with the dominant X-linked form of Charcot-Marie-Tooth (CMTX1) neuropathy. Since some CMTX1 patients show no mutations in their cx32 gene coding region, it was speculated that these patients carry mutations in the promoter region of the gene. This paper describes the organization of the human cx32 gene and its tissue-specific transcription. The gene consists of three exons that are alternatively spliced to produce mRNAs with different 5′-untranslated regions (UTRs). Transcription is initiated from two tissue-specific promoters. In liver and pancreas, promoter P1. located more than 8 kb upstream of the translation start codon, is used, and the transcript is processed to remove a large intron. In contrast, in nerve cells, transcription is initiated from promoter P2, located 497 bp upstream from the translation start codon, and the transcript is processed to remove a small 355-pb intron. The downstream exon. which includes the entire coding sequence, is shared by both mRNAs. CMTX1 patients with a normal cx32 coding region are expected to have mutations in this newly described promoter P2 rather than the known promoter P1.
Data refinement, call by value and higher order programs
Authors: Naumann David A.
Published: February 2005

Using 2-categorical laws of algorithmic refinement, we show soundness of data refinement for stored programs and hence for higher order procedures with value/result parameters. The refinement laws hold in a model that slightly generalizes the standard predicate transformer semantics for the usual imperative programming constructs including prescriptions.
The completeness of functional logic
Authors: Nickolas Peter
Published: February 2005

A new first-order logic, functional logic, was proposed recently by Staples, Robinson and Hazel. The logic provides a formal means of describing and reasoning about dependence on an implicit parameter, a prime motivation being the unification of the Hoare logic used to reason about procedural programs with the powerful and well established techniques of classical logic. Viewed more abstractly, independently of possible applications, functional logic may be described as a logic with primitives, axioms and inference rules appropriate for reasoning about the properties of mathematical functions. In this paper, the completeness of functional logic is proved; that is, it is shown that any term of a theory in the logic which is true in all models is a theorem.
A formal model of asynchronous communication and its use in mechanically verifying a biphase mark protocol
Authors: Moore J Strother
Published: February 2005

We present a formal model of asynchronous communication between two digital hardware devices. The model takes the form of a function in the Boyer-Moore logic. The function transforms the signal stream generated by one processor into that consumed by an independently clocked processor, given the phases and rates of the two clocks and the communications delay. The model can be used quantitatively to derive concrete performance bounds on communications at ISO protocol level 1 (physical level). We use the model to show that an 18-bit/cell biphase mark protocol reliably sends messages of arbitrary length between two processors provided the ratio of the clock rates is within 5% of unity.
Duration calculus: Logical foundations
Authors: Hansen Michael R. , Chaochen Zhou
Published: February 2005

The Duration Calculus (abbreviated DC) represents a logical approach for formal design of real-time systems, where real numbers are used to model time and Boolean valued functions over time are used to model states and events of real-time systems. Since its introduction, DC has been applied to many case studies and it has been extended in several directions. The aim of this paper is to provide a thorough presentation of the logic.
Running programs backwards: The logical inversion of imperative computation
Authors: Ross Brian J.
Published: February 2005

Imperative programs can be inverted directly from their forward-directed program code with the use of logical inference. The relational semantics of imperative computations treats programs as logical relations over the observable state of the environment, which is taken to be the state of the variables in memory. Program relations denote both forward and backward computations, and the direction of the computation depends upon the instantiation pattern of arguments in the relation. This view of inversion has practical applications when the relational semantics is treated as a logic program. Depending on the logic programming inference scheme used, execution of this relational program can compute the inverse of the imperative program. A number of nontrivial imperative computations can be inverted with minimal logic programming tools.
A methodology for designing proof rules for fair parallel programs
Authors: Jutla Charanjit S. , Rao Josyula R.
Published: February 2005

We propose a methodology for designing sound and complete proof systems for proving progress properties of parallel programs under various fairness assumptions. Our methodology begins with a branching time temporal logic formula (CTL*) formula that expresses progress under a fairness assumption. The next step obtains an equivalent fixpoint characterization of this CTL*formula in theμ-calculus. The final step uses the fixpoint characterizations to extract proof systems for proving progress under the fairness constraint. The methodology guarantees that the proof rules so obtained are sound and relatively complete in the sense of Cook.
Limits of formal methods
Authors: Kneuper Ralf
Published: February 2005

Formal methods can help to increase the correctness and trustworthiness of the software developed. However, they do not solve all the problems of software development. This paper analyses some limitations of formal methods.
The Use of SI-Algebra in the design of sequencer circuits
Authors: Josephs Mark B. , Bailey Andrew M.
Published: February 2005

One approach to the design of VLSI systems involves the use of asynchronous circuits that communicate by handshaking with each other. The control circuitry generated when following this approach often includes large trees of binary sequencer components. This paper demonstrates that there is scope here for optimization (in order to improve size, speed and energy consumption). Indeed, an industrial-strength silicon compiler has now been modified to take advantage of this fact.

The problem that is addressed concerns the design of efficient control circuits that sequenceNfour-phase handshakes (N> 2). Muller's speed-independent discipline facilitates the design of such circuits. SI-Algebra, a calculus that supports that discipline, is used to specify the problem and to verify (using recursion-induction) various implementations. Simple counting arguments at the gate level establish that optimization using these implementations is worthwhile.
The applicability of discrete performance estimation methods to VLSI design
Authors: Williams Alan
Published: February 2005

Conditions necessary to produce correct asymptotic complexity results and realistic performance estimates for VLSI devices, using discrete high-level VLSI complexity models, are examined. A set of design constraints is formulated, based on results from two experiments involving suitably designed and fabricated VLSI devices. The basis of the complexity model is modified so that it satisfies the constraints. A case-study for an integer multiplier design shows that the modified model produces asymptotic results in agreement with empirical measurements. Low-level performance estimates are then obtained using the RC network delay model in conjunction with the VLSI complexity model.
Correct translation of data parallel assignment onto array processors
Authors: Wray J. P. , Stewart A.
Published: February 2005

Two models of computation which are suitable for the description of parallel scientific calculations on large data structures are presented. Data parallel assignment is a construct which may be used to specify the application of a set of order independent fine grained operations to a regular data structure. It is formulated in a machine independent way and, consequently, is suitable for implementation on a range of novel parallel architectures. An operational model of data parallel computation is provided by specifying a model array processor. The specification captures the essential features of the class of array processors and it may be instantiated in order to define a particular machine. A formal operational semantics of data parallel assignment is given for the model array processor. The translation mechanism is shown to be correct. The exercise clarifies some of the issues in deciding whether or not it is feasible to translate data parallel assignment directly onto array processor architectures.
Error in the UNITY substitution rule for subscripted operators
Authors: Prasetya I. S. W. B.
Published: February 2005

UNITY, introduced by Chandy and Misra [ChM88], is a programming logic intended to reason about temporal properties of distributed programs. Despite the fact that UNITY does not have the full power of, for example, linear temporal logic, it enjoys popularity due to its simplicity.

There was however a serious problem with the Substitution Rule. The logic is incomplete without the rule, and with the rule it is inconsistent.

Latterly Beverly Sanders introduced the concept of strongest invariant and proposed a new definition for UNITY [San91] that fixes the problem with the Substitution Rule. For the benefit of program union, she also introduced the concept of subscripted properties and claimed a generalized version of Substitution Rule for the subscripted properties.

This report presents an example that shows that the latter claim is false. A proposal as how to fix this follows.
A layered semantics for a parallel object-oriented language
Authors: America Pierre , Rutten Jan
Published: February 2005

We develop a denotational semantics for POOL, a parallel object-oriented programming language. The main contribution of this semantics is an accurate mathematical model of the most important concept in object-oriented programming: the object. This is achieved by structuring the semantics in layers working at three different levels: for statements, objects and programs. For each of these levels we define a specialized mathematical domain of processes, which we use to assign a meaning to each language construct. This is done in the mathematical framework of complete metric spaces. We also define operators that translate between these domains. At the program level we give a precise definition of the observable input/output behaviour of a particular program, which could be used at a later stage to decide the issue of full abstractness. We illustrate our semantic techniques by first applying them to a toy language similar to CSP.
Transformation of programs for fault-tolerance
Authors: Liu Zhiming , Joseph Mathai
Published: February 2005

In this paper we describe how a program constructed for afault-freesystem can be transformed into afault-tolerantprogram for execution on a system which is susceptible to failures. A program is described by a set of atomic actions which perform transformations from states to states. We assume that a fault environment is represented by a programF. Interference by the fault environmentFon the execution of a programPcan then be described as afault-transformationℱ which transformsPinto a program ℱ(P). This is proved to be equivalent to the programP□PF, wherePFis derived fromPandF, and □ defines the union of the sets of actions ofPandFP. A recovery transformation ℛ transformsPinto a program ℛ(P) =P□Rby adding a set ofrecovery actions R, called arecovery program. If the system isfailstopand faults do not affect recovery actions, we have ℱ(ℛ(P))=ℱ(P)□R=P□PF□RWe illustrate this approach to fault-tolerant programming by considering the problem of designing a protocol that guarantees reliable communication from a sender to a receiver in spite of faults in the communication channel between them.
Verified compilation of communicating processes into clocked circuits
Authors: O'Leary John , Brown Geoffrey , Luk Wayne
Published: February 2005

We have previously developed a verified algorithm for compiling programs written in an occam-like language into delay-insensitive circuits. In this paper we show how to retarget our compiler for clocked circuits. Since verifying a hardware compiler is a huge effort, it is significant that we are able to retarget our compiler proof without recreating that effort.

The chief contribution of this paper is the methodology used for retargeting our compiler which is based upon a new model for systems with both synchronous and asynchronous behaviour. The retargeting proof utilizes both theorems proved algebraically by hand and theorems proved automatically by state exploration. The technique of protocol conversion is used extensively in modularizing the proof of the clocked implementation.
Unification: A case-study in data refinement
Authors: Spivey J. M.
Published: February 2005

In this paper, the Z notation is used to develop a small theory of terms and substitutions within which a simple unification algorithm can be specified and proved correct. Particular emphasis is placed on the use of Z's mathematical data types to simplify the development and structure of this theory. The correctness of an abstract version of the algorithm is proved first; this version operates on substitutions by composition. Then data refinement is used to show that the substitutions can be represented by ‘binding functions’ that make composition a particularly efficient operation. The approach taken in this paper is compared with the approaches of three previous papers based on VDM.

The contribution of this paper is to show how data refinement can be used to explain the design decisions behind a non-trivial program, and to provide a point of comparison between Z and VDM approaches to the same problem.
A formal model of explanation
Authors: Todd Bryan S. , Stamper Richard
Published: February 2005

As information systems become more complex, formal methods offer a solution to the increasing problem of ensuring correctness of design and implementation. This paper illustrates the use of mathematical specification to formalise the notion of ‘explanation’. This is relevant to any information system which engages in inference. An information system is regarded as a homogeneous function on states of information. An explanation for a conclusion is regarded as a weakening of the theory relating input to output, such that the same conclusion is reached. As an example, the specification is implemented for a simple statistical classifier to assist medical diagnosis.
A mechanical proof of Segall's PIF algorithm
Authors: Hesselink Wim H.
Published: February 2005

We describe the construction of a distributed algorithm with asynchronous communication together with a mechanically verified proof of correctness. For this purpose we treat Segall's PIF algorithm (propagation of information with feedback). The proofs are based on invariants, and variant functions for termination. The theorem prover NQTHM is used to deal with the many case distinctions due to asynchronous distributed computation. Emphasis is on the modelling assumptions, the treatment of nondeterminacy, the forms of termination detection, and the proof obligations for a complete mechanical proof. Finally, a comparison is made with (the proof of) the minimum spanning tree algorithm of Gallager, Humblet, and Spira, for which the technique was developed.
Towards a practitioners' approach to Abadi and Lamport's method
Authors: Engelhardt Kai , de Roever Willem -Paul
Published: February 2005

Our own basic intuitions are presented when introducing the method developed by Abadi and Lamport in [AbL88a] for proving refinement between specifications of nondeterministic programs correct to people unacquainted with it. The example we use to illustrate this method is a nontrivial communication protocol that provides a mechanism analogous to message passing between migrating processes within a fixed finite network of nodes due to Kleinman, Moscowitz, Pnueli and Shapiro [KMP91]. Especially the cruel last step of a three step refinement proof of that protocol gives rise to a deeper understanding of, and some small enhancements to, Abadi and Lamport's 1988 method.
Specifying distributed CICS in Z: Accessing local and remote resources
Authors: Houston Iain S. C. , Josephs Mark B.
Published: February 2005

The CICS/ESA Intercommunication Guide is a source of information about distributed CICS systems. Among other things, it describes how an application program running on one system can issue a command that will be shipped to a remote system. A resource manager located at the remote system will execute the command and ship back a response.

This paper presents a formal specification of the above interaction between application programs and resource managers. Some familiarity with the Z specification language is assumed. The structure of the specification illustrates how it is possible to address separately, and later combine, different aspects of a complex system, including its distributed nature.
Priority as extremal probability
Authors: Smolka Scott A. , Steffen Bernhard
Published: February 2005

We extend the stratified model of probabilistic processes to obtain a very general notion of
process priority.
The main idea is to allow probability guards of value 0 to be associated with alternatives of a probabilistic summation expression. Such alternatives can be chosen only if the non-zero alternatives are precluded by contextual constraints. We refer to this model as one of “extremal probability” and to its signature as
PCCS
ζ
. We provide
PCCS
ζ
with a structural operational semantics and a notion
of probabilistic bisimulation
, which is shown to be a congruence. Of particular interest is the abstraction
PCCS
π
of
PCCS
ζ
in which all non-zero probability guards are identified.
PCCS
π
represents a customized framework for reasoning about priority, and covers all features of process algebras proposed for reasoning about priority that we know of.
A criterion for atomicity
Authors: Anderson James H. , Gouda Mohamed G.
Published: February 2005

Most proof methods for reasoning about concurrent programs are based upon the
interleaving semantics
of concurrent computation: a concurrent program is executed in a stepwise fashion, with only one enabled action being executed at each step. Interleaving semantics, in effect, requires that a concurrent program be executed as a nondeterministic sequential program. This is clearly an abstraction of the way in which concurrent programs are actually executed. To ensure that this is a reasonable abstraction, interleaving semantics should only be used to reason about programs with “simple” actions; we call such programs “atomic”. In this paper, we formally characterise the class of atomic programs. We adopt the criterion that a program is
atomic
if it can be implemented in a wait-free, serialisable manner by a primitive program. A program is
primitive
if each of its actions has at most one occurrence of a shared bit, and each shared bit is read by at most one process and written by at most one process. It follows from our results that the traditionally accepted atomicity criterion, which allows each action to have at most one occurrence of a shared variable, can be relaxed, allowing programs to have more powerful actions. For example, according to our criterion, an action can read any finite number of shared variables, provided it writes no shared variable.
Reasoning about Prolog programs: From modes through types to assertions
Authors: Apt Krzysztof R. , Marchiori Elena
Published: February 2005

We provide here a systematic comparative study of the relative strength and expressive power of a number of methods for program analysis of Prolog. Among others we show that these methods can be arranged in the following hierarchy: mode analysis ⇒ type analysis ⇒ monotonic properties ⇒ nonmonotonic run-time properties. We also discuss a method allowing us to prove global run-time properties.
The weakest precondition calculus: Recursion and duality
Authors: Bonsangue Marcello M. , Kok Joost N.
Published: February 2005

An extension of Dijkstra's guarded command language is studied, including unbounded demonic choice and a backtrack operator. We consider three orderings on this language: a refinement ordering defined by Back, a new deadlock ordering, and an approximation ordering of Nelson. The deadlock ordering is in between the two other orderings. All operators are monotonic in Nelson's ordering, but backtracking is not monotonic in Back's ordering and sequential composition is not monotonic for the deadlock ordering. At first sight recursion can only be added using Nelson's ordering. We show that, under certain circumstances, least fixed points for non-monotonic functions can be obtained by iteration from the least element. This permits the addition of recursion even using Back's ordering or the deadlock ordering in a fully compositional way. In order to give a semantic characterization of the three orderings that relates initial states to possible outcomes of the computation, the relation between predicate transformers and discrete power domains is studied. We consider (two versions of) the Smyth power domain and the Egli-Milner power domain.
Extending hoare logic to real-time
Authors: Hooman Jozef
Published: February 2005

Classical Hoare triples are modified to specify and design distributed real-time systems. The assertion language is extended with primitives to express the timing of observable actions. Further the interpretation of triples is adapted such that both terminating and nonterminating computations can be specified. To verify that a concurrent program, with message passing along asynchronous channels, satisfies a real-time specification, we formulate a compositional proof system for our extended Hoare logic. The use of compositionality during top-down design is illustrated by a process control example of a chemical batch processing system.
Model-checking discrete duration calculus
Authors: Hansen Michael R.
Published: February 2005

Duration Calculus was introduced in [ZHR91] as a logic to specify and reason about requirements for real-time systems. It is an extension of Interval Temporal Logic [Mos85] where one can reason about integrated constraints over time-dependent and Boolean valued states without explicit mention of absolute time. Several major case studies, e.g. the gas burner system in [RRH93], have shown that Duration Calculus provides a high level of abstraction for both expressing and reasoning about specifications. Using Timed Automata [A1D92] one can express how real-time systems can be constructed at a level of detail which is close to an actual implementation. We consider in the paper the correctness of Timed Automata with respect to Duration Calculus formulae. For a subset of Duration Calculus, we show that one can automatically verify whether a Timed Automaton ℳ is correct with respect to a formulaD, abbreviated ℳ ⊨D, i.e. one can domodel-checking. The subset we consider is expressive enough to formalize the requirements to the gas burner system given in [RRH93]; but only for a discrete time domain. Model-checking is done by reducing the correctness problem ℳ ⊨D to the inclusion problem of regular languages.
Retargeting a hardware compiler using protocol converters
Authors: Brown Geoffrey , Luk Wayne , O'Leary John
Published: February 2005

We show how to retarget a compiler for occam-like programs from generating two-phase delay-insensitive circuits to generating four-phase speed independent circuits. The specifications of the two-phase circuit elements for our compiler are used to produce a set of equivalent specifications for four-phase circuit elements using a set of protocol converters. Automatic tools have been used in checking that our four-phase implementations satisfy their specifications.
Superposition refinement of reactive systems
Authors: Back R. J. R. , Sere K.
Published: February 2005

Superposition refinement enhances an algorithm by superposing one computation mechanism onto another mechanism, in a way that preserves the behavior of the original mechanism. Superposition seems to be particularly well suited to the development of parallel and distributed programs: an originally simple sequential algorithm can be extended with mechanisms that distribute control and state information to many processes, thus permitting efficient parallel execution of the algorithm. We will show in this paper how superposition of reactive systems is expressed in the refinement calculus. We illustrate the power of this method by a case study, showing how a distributed broadcasting system is derived through a sequence of superposition refinements.
A static view of localities
Authors: Aceto Luca
Published: February 2005

This paper proposes alternative, effective characterizations for nets of automata of the location equivalence and preorder presented by Boudol et al. in the companion paper [BCHK]. Contrary to the technical development in the above given reference, where locations are dynamically associated to the subparts of a process in the operational semantics, the equivalence and preorder we propose are based on a static association of locations to the parallel components of a net. Following this static approach, it is possible to give these “distributed nets” a standard operational semantics which associates with each net a finite labelled transition system. Using this operational semantics for distributed nets, we introduce effective notions of equivalence and preorder which are shown to coincide with those proposed in [BCHK].
Lithium inhibits brown adipocyte differentiation
Authors: Rodrı́guez de la Concepción Maria Luisa , Yubero Pilar , Iglesias Roser , Giralt Marta , Villarroya Francesc
Published: February 2005

Lithium impairs the appearance of the characteristic morphology of brown adipocytes and downregulates the expression of marker genes of brown adipocyte differentiation. These effects are dose‐dependent and are more pronounced when exposure of preadipocytes to lithium is initiated at early stages of differentiation. Although lithium reduces the expression of genes common to both white and brown adipocytes [fatty acid binding protein aP2 (aP2/FABP) or peroxisome proliferating activated receptor γ], genes expressed differentially in brown adipocytes, i.e., uncoupling protein 1, PPAR gamma coactivator‐1α, and peroxisome proliferating activated receptor α, are particularly sensitive to lithium treatment‐dependent downregulation. Brown adipocytes appear as preferential targets of the inhibitory action of lithium on adipocyte differentiation.
Interactome modeling
Authors: Vidal Marc
Published: February 2005

A long‐term goal of the field of interactome modeling is to understand how global and local properties of complex macromolecular networks impact on observable biological properties, and how changes in such properties can lead to human diseases. The information available at this stage of development of the field provides strong evidence for the existence of such interesting global and local properties, but also demonstrates that many more datasets will be needed to provide accurate models with increasingly predictive capacity. This review focuses on an early attempt at mapping a multicellular interactome network and on the lessons learned from that attempt.
Similarities and differences in the transcriptional regulation of the leptin gene promoter in gastric and adipose cells
Authors: Goı¨ot Hélène , Laigneau Jean-Pierre , Devaud Hélène , Sobhani Iradj , Bado André
Published: February 2005

The stomach was reported to synthesize and secrete leptin mainly in the gastric lumen. Gastric leptin release is markedly increased after food intake, by vagal cholinergic stimulation and by cholecystokinin and secretin. Here we show that human gastric MKN‐74 cells produce leptin that increases upon challenge with cholecystokinin, insulin, glucocorticoids and all‐trans retinoic acid through activation of the leptin gene promoter. In addition, we demonstrate that forskolin and BRL37344 which increased cAMP levels, fail to affect the activity of leptin gene promoter in MKN74 expressing β3‐adrenoceptor cells but, induce a 2‐fold decrease in this activity in adipose 3T3‐L1 cells. These data described for the first time, similarities and more interestingly, differences in the regulation of the leptin gene promoter in gastric cells as compared to adipocytes.
Endopolyphosphatase in Saccharomyces cerevisiae undergoes post‐translational activations to produce short‐chain polyphosphates
Authors: Shi Xiaobing , Kornberg Arthur
Published: February 2005

Endopolyphosphatase (Ppn), responsible for cleavage of long chain inorganic polyphosphate (poly P) of several hundred residues to generate progressively shorter chains, has been identified in mammalian cells and purified from Saccharomyces cerevisiae. Disruption of the encoding gene, PHM5, in S. cerevisiae resulted in a mutant that showed limited growth and failure to survive in a minimal medium. The limited digestion products of the yeast enzyme Ppn1 judged to be P3 and P60 have now, with the homogeneous enzyme and improved separation methods, been demonstrated to be Pi and P3. Ppn1, a homotetramer of a 35‐kDa subunit, is of vacuolar origin and requires protease activation of a 78 kDa (674‐aa) precursor polypeptide (prePpn1). The protease‐processed Ppn1 has been purified 3800‐fold to homogeneity and the protease cleavage sites determined. Both termini of prePpn1 and the post‐translational modification of N‐glycosylations are essential for the protease‐mediated maturation of Ppn1.
Fast-flowing outlet glaciers of the Last Glacial Maximum Patagonian Icefield
Authors: Glasser Neil F. , Jansson Krister N.
Published: February 2005

Glacial geomorphology around the Northern Patagonian Icefield indicates that a number of fast-flowing outlet glaciers (the continuation of ice streams further upglacier) drained the icefield during the Last Glacial Maximum. These topographically controlled fast-flowing glaciers may have dictated the overall pattern of Last Glacial Maximum ice discharge, lowered the ice-surface profile, and forced the ice-divide westward. The influence of the fast-flowing outlet glaciers on icefield behavior also helps to explain why the configuration of the Patagonian Icefield at the Last Glacial Maximum is not accurately represented in existing numerical ice-sheet models. Fast-flowing outlet glaciers would have strongly influenced ice discharge patterns and therefore partially decoupled the icefield from climatically induced changes in thickness and extent.
Community outreach for untreated schizophrenia in rural India: a follow-up study of symptoms, disability, family burden and costs
Authors: SRINIVASA MURTHY R. , KISHORE KUMAR K. V. , CHISHOLM D. , THOMAS T. , SEKAR K. , CHANDRASHEKAR C. R.
Published: February 2005

Background. In resource-poor countries, there remains an alarming treatment gap for people with schizophrenia, particularly those living in rural areas. Decentralization of mental health services, including community-based outreach programmes, represents one obvious strategy for bringing appropriate care to these communities. This study set out to assess the costs and effects of such a programme in rural Karnataka in India.

Method. Eight rural communities were visited by an outreach team, who identified cases of drug-naive or currently untreated schizophrenia. Recruited cases were provided with appropriate psychotropic medication and psychosocial support, and after obtaining informed consent were assessed every 3 months over one and a half years on symptomatology, disability, family burden, resource use and costs. A repeated-measures analysis was carried out to test for significant change in these outcome measures over this period.

Results. A total of 100 cases of untreated schizophrenia were recruited, of whom 28% had never received antipsychotic medication and the remaining 72% had not been on medication for the past 6 months. Summary scores for psychotic symptoms, disability and family burden were all reduced significantly, with particular improvement observed at the first follow-up assessment. Increases in treatment and community outreach costs over the follow-up period were accompanied by reductions in the costs of informal-care sector visits and family care-giving time.

Conclusions. Efforts to organize community-based care such as outreach services for people with schizophrenia living in more remote areas of resource-constrained countries can bring substantial benefits to patients and families alike.
Childhood physical and sexual abuse and subsequent depressive and anxiety disorders for two American Indian tribes
Authors: LIBBY ANNE M. , ORTON HEATHER D. , NOVINS DOUGLAS K. , BEALS JANETTE , MANSON SPERO M.
Published: February 2005

Background. This study examined the relationship of childhood abuse, both physical and sexual, with subsequent lifetime depressive and anxiety disorders – depression or dysthymia, post-traumatic stress disorder (PTSD), and panic or generalized anxiety disorder (GAD) – among American Indians (AIs).

Method. Three thousand and eighty-four AIs from two tribes – Southwest and Northern Plains – participated in a large-scale, community-based study. Participants were asked about traumatic events and family history, and were administered standard diagnostic measures of depressive/anxiety disorders.

Results. Prevalence of childhood physical abuse was approximately 7% for both tribes. The Southwest tribe had higher prevalence of depressive and anxiety disorders, with rates of PTSD being the highest. Childhood physical abuse was significant in bivariate models of depressive/anxiety disorders, and remained so in the multivariate models.

Conclusions. Childhood physical abuse was a significant predictor of all disorder groups for males in both tribes except for panic/GAD for the Northern Plains tribe in multivariate models; females showed a more varied pattern. Childhood sexual abuse did not significantly differ for males and females, and was an independent predictor of PTSD for both tribes, controlling for childhood physical abuse and other factors, and was significant for the other disorder groups only in the Southwest. Additional covariates that increased the odds of depressive/anxiety disorders were adult physical or sexual victimization, chronic illness, lifetime alcohol or drug disorder, and parental problems with depression, alcohol, or violence. Results provided empirical evidence of childhood and later life risk factors and expanded the population at risk to include males.
Cyanopolyynes: carbon chains formation in a carbon arc mimicking the formation of carbon chains in the circumstellar medium
Authors: Cataldo Franco
Published: February 2005

Monocyanopolyynes and dicyanopolyynes can be synthesized quite easily by the submerged electric arc. Monocyanopolyynes having the general formula H[bond](C[triple bond]C)n[bond]C[triple bond]N can be synthesized together with ordinary polyynes series H[bond](C[triple bond]C)n[bond]H by arcing graphite electrodes in acetonitrile. Dicyanopolyynes N[triple bond]C[bond](C[triple bond]C)n[bond]C[triple bond]N are produced almost pure by arcing graphite electrodes directly into liquid nitrogen. These molecules are present in the envelope of post-AGB (asymptotic giant branch), carbon-rich giant stars and also in dark molecular clouds. They are incorporated into comets and also into other primitive materials and may play a role in the prebiotic synthesis of more complex organic molecules having a biological significance. Furthermore, the cyanopolyynes are involved in the atmospheric chemistry of some bodies of the solar system. The discovery of the easy formation of these molecules under laboratory conditions may explain why these molecules are so ubiquitous in space and may also stimulate new ideas about the mechanism of their formation.
Steady-state kinetics and inhibition of anaerobically purified human homogentisate 1,2-dioxygenase
Authors: VELDHUIZEN Edwin J. A. , VAILLANCOURT Frédéric H. , WHITING Cheryl J. , HSIAO Marvin M.-Y. , GINGRAS Geneviève , XIAO Yufang , TANGUAY Robert M. , BOUKOUVALAS John , ELTIS Lindsay D.
Published: February 2005

HGO (homogentisate 1,2-dioxygenase; EC 1.13.11.5) catalyses the O2-dependent cleavage of HGA (homogentisate) to maleylacetoacetate in the catabolism of tyrosine. Anaerobic purification of heterologously expressed Fe(II)-containing human HGO yielded an enzyme preparation with a specific activity of 28.3± 0.6 μmol·min−1·mg−1 (20 mM Mes, 80 mM NaCl, pH 6.2, 25 °C), which is almost twice that of the most active preparation described to date. Moreover, the addition of reducing agents or other additives did not increase the specific activity, in contrast with previous reports. The apparent specificity of HGO for HGA was highest at pH 6.2 and the steady-state cleavage of HGA fit a compulsory-order ternary-complex mechanism (Km value of 28.6±6.2 μM for HGA, Km value of 1240±160 μM for O2). Free HGO was subject to inactivation in the presence of O2 and during the steady-state cleavage of HGA. Both cases involved the oxidation of the active site Fe(II). 3-Cl HGA, a potential inhibitor of HGO, and its isosteric analogue, 3-Me HGO, were synthesized. At saturating substrate concentrations, HGO cleaved 3-Me and 3-Cl HGA 10 and 100 times slower than HGA respectively. The apparent specificity of HGO for HGA was approx. two orders of magnitude higher than for either 3-Me or 3-Cl HGA. Interestingly, 3-Cl HGA inactivated HGO only twice as rapidly as HGA. This contrasts with what has been observed in mechanistically related dioxygenases, which are rapidly inactivated by chlorinated substrate analogues, such as 3-hydroxyanthranilate dioxygenase by 4-Cl 3-hydroxyanthranilate.
Thickness scaling of the space-charge-limited current in poly(p-phenylene vinylene)
Authors: Blom P. W. M. , Tanase C. , de Leeuw D. M. , Coehoorn R.
Published: February 2005

Charge transport in light-emitting diodes (LEDs) based on a poly(p-phenylene vinylene) (PPV) derivative is investigated as a function of sample thickness. Via the thickness dependence, the contributions from the electric field and charge carrier density to the mobility in space-charge-limited (SCL) diodes can be disentangled. It is demonstrated that a field-dependent mobility weakens the thickness dependence of the SCL current, whereas a carrier-density-dependent mobility gives rise to an enhanced thickness dependence. The enhanced thickness dependence of the experimental SCL current in PPV is in agreement with the predictions using a density-dependent mobility only. This observation confirms that in PPV-based LEDs, the hole transport is dominated by filling of the localized states.
Nucleation and growth processes of α-Fe nanocrystals in amorphous NdFeBCoDy: In situ x-ray diffraction studies
Authors: Li W. , Li X. H. , Sun H. Y. , Zhang J. W. , Zhang X. Y.
Published: February 2005

For a detailed understanding of formation processes of nanocrystals in an amorphous matrix, the study of crystal nucleation and growth processes is of basic interest. In the present study, these processes of α-Fe nanocrystals in amorphous NdFeCoDyB have been studied separately by employing in situ high-temperature x-ray diffraction measurements. A small growth activation energy Eg=(1.8±0.2)eV was determined from the isothermal time dependence of the grain size of α-Fe crystals. By these data together with the nucleation activation energy En=(3.0±0.1)eV, a coarse grain size for the α-Fe phase in the α-Fe∕Nd2Fe14B nanocomposites developed from amorphous NdFeBCoDy can be understood.
Estimation of the tip field enhancement on a field emitter under laser illumination
Authors: Gault B. , Vurpillot F. , Bostel A. , Menand A. , Deconihout B.
Published: February 2005

We report the experimental evidence of controlled field evaporation of atoms from the surface of a tip-like-shape specimen with subwavelength dimensions by means of subpicosecond laser pulses. It is shown that the evaporation is assisted by the intrinsic laser electric field without any significant thermal activation. The single-atom detection sensitivity of the field ion microscope is used to get an accurate measurement of the electric field enhancement factor at the tip apex as a function of the wave polarization. The absence of thermal diffusion of atoms at the tip surface prior to field evaporation, demonstrates the feasibility of a laser assisted three-dimensional atom probe.
Biomass, persistence and drought resistance of nine lucerne varieties in the dry environment of west China
Authors: Guo Zheng Gang , Liu Hui Xia , Wang Suo Min , Tian Fu Ping , Cheng Guo-Dong
Published: February 2005

Forage yield and density are common selection criteria for assessing the suitability of lucerne varieties in high rainfall conditions and under irrigation. However, selection criteria for assessing the suitability of lucerne varieties is not well defined in dryland farming systems. This study combines forage yield, plant density, root biomass and proline content in the plant leaf to compare the suitability of 1 local and 8 introduced lucerne (Medicago sativa) varieties over 3 years in the dry environment of west China. The results of this study indicated that the above measurements significantly differed among the 9 lucerne varieties, and also showed that suitability of lucerne varieties varied based on different indicators. Ameristand 201 and Algonquin performed well in terms of forage yield. Ameristand 201 and Sandili were well-adapted varieties based on root biomass and Ameristand 201 was the first selected variety in terms of drought resistance. Combining initial establishment density and its decline over years indicated that Sandili maintained good persistence. A cluster analysis of 9 lucerne varieties indicated that Ameristand 201 was very suitable for sowing in the dry Loess Plateau, a high water-erosion region in west China.
Status of Australian sea lions, Neophoca cinerea, and New Zealand fur seals, Arctocephalus forsteri, on Eyre Peninsula and the far west coast of South Australia
Authors: Shaughnessy P. D. , Dennis T. E. , Seager P. G.
Published: February 2005

Two seal species breed on the west coast of South Australia, the Australian sea lion, Neophoca cinerea, and the New Zealand fur seal, Arctocephalus forsteri. Aerial surveys were conducted at intervals of ~3 months between April 1995 and June 1997 to determine the breeding status of sea lions and timing of pupping seasons. Ground surveys between October 1994 and April 2004 aimed at counting sea lions and fur seals, particularly pups. In all, 27 sites were examined. Six new sea lion breeding colonies were documented, at Four Hummocks, Price, North Rocky, Dorothee, West Waldegrave and Nicolas Baudin Islands. All were found or confirmed by ground survey. Pup numbers were equivalent to 12% of the total number of pups estimated in surveys conducted from 1987 to 1992, but primarily in 1990. The sighting of brown pups on aerial surveys of Ward Island, Middle and Western Nuyts Reef supports earlier indications, based on dead pups, that they are breeding colonies. The timing of pupping seasons is not synchronous; estimates are presented for colonies between 1995 and early in 2004, with predictions to the end of 2005. The abundance estimates of sea lion pups highlight the importance of visiting a colony early in the pupping season to determine when pupping begins and ~5 months later when the maximum number of pups is expected. For the New Zealand fur seal, small numbers of pups were recorded at Dorothee, West Waldegrave and Nicolas Baudin Islands, and at Nuyts Reef. These and the previously unknown sea lion breeding colonies on the west coast of South Australia suggest that further colonies may remain to be documented. Because planning for aquaculture ventures is active in South Australia, it is important that the localities and status of sea lion and fur seal colonies be established unequivocally to ensure that the need for Prohibited Area status for islands with breeding colonies and for Marine Protected Areas around them is noted.
Characteristics of sap trees used by yellow-bellied gliders in southern Queensland
Authors: Eyre Teresa J. , Goldingay Ross L.
Published: February 2005

An extensive survey was conducted to locate sap trees used by the yellow-bellied glider (Petaurus australis) throughout the forests and woodlands of southern Queensland, across an area of 43.7 million hectares. We recorded the characteristics of 478 sap trees located at 109 of 297 sites surveyed. Only 13 tree species were selected by gliders for sap feeding throughout the study region, with the grey gum species Eucalyptus longirostrata and E. biturbinata most likely to be incised for sap. Of the tree species used for sap feeding by gliders, trees >40 cm in diameter at breast height (dbh) were used more than would be expected on the basis of their abundance in the forest. The number of sap trees with active and recently active feed scars at a site ranged from 0 to 12. Factors that appear to influence the abundance of active and recently active sap trees at a site include intensity of disturbance (basal area of cut stumps and dead trees), the number of stems in the 41–60 and 61–80 cm dbh classes, and number of Myrtaceae species. The response to these variables could be indicative of habitat quality, and the availability of alternative foraging substrates such as flower cover and decorticating bark. Intensification of selective logging in south-east Queensland, as an outcome of the Southeast Queensland Regional Forest Agreement, could potentially marginalise glider habitat. This would necessitate the retention of potential, or ‘recruit’, sap trees to maintain yellow-bellied glider habitat in these areas.