bluuebunny/crossref_metadata_2025 huggingface dataset:
Drug release from pH‐responsive thermogelling pentablock copolymers
Authors: Determan Michael D. , Cox James P. , Mallapragada Surya K.
Published: November 2006

A novel pH‐dependent injectable sustained delivery system was developed by utilizing a cationic pentablock copolymer that exhibits a thermoreversible sol‐gel transition. Aqueous solutions of the pentablock copolymer, consisting of poly(2‐diethylaminoethyl‐methyl methacrylate)‐poly(ethylene oxide)‐poly(propylene oxide)‐poly(ethylene oxide)‐poly(2‐diethylaminoethyl‐methyl methacrylate) (PDEAEM25‐PEO100‐PPO65‐PEO100‐PDEAEM25) exhibit temperature and pH dependent micellization due to the lower critical solution temperature of the PPO blocks and the polyelectrolyte character of the PDEAEM blocks, respectively. Aqueous solutions of the copolymers above 12 wt % are free flowing liquids at room temperature and form elastic physical hydrogels reversibly above 37°C. Hydrophobic probe absorbance studies indicate that pentablock copolymer micelles increase the solubility of sparingly soluble drugs. Solutions of the pentablock copolymer that form gels at body temperature exhibit sustained zero‐order release in in vitro experiments. The release rates of model drugs and proteins were significantly influenced by the pH of the release media, thereby making these polymers ideal candidates for modulated drug delivery. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res 2007
Unicorns in the world of chemical bonding models
Authors: Frenking Gernot , Krapp Andreas
Published: November 2006

The appearance and the significance of heuristically developed bonding models are compared with the phenomenon of unicorns in mythical saga. It is argued that classical bonding models played an essential role for the development of the chemical science providing the language which is spoken in the territory of chemistry. The advent and the further development of quantum chemistry demands some restrictions and boundary conditions for classical chemical bonding models, which will continue to be integral parts of chemistry. © 2006 Wiley Periodicals, Inc. J Comput Chem 2007
Bond electron pair: Its relevance and analysis from the quantum chemistry point of view
Authors: Malrieu Jean‐Paul , Guihéry Nathalie , Calzado Carmen jiménez , Angeli Celestino
Published: November 2006

This paper first comments on the surprisingly poor status that Quantum Chemistry has offered to the fantastic intuition of Lewis concerning the distribution of the electrons in the molecule. Then, it advocates in favor of a hierarchical description of the molecular wave‐function, distinguishing the physics taking place in the valence space (in the bond and between the bonds), and the dynamical correlation effects. It is argued that the clearest pictures of the valence electronic population combine two localized views, namely the bond (and lone pair) Molecular Orbitals and the Valence Bond decomposition of the wave‐function, preferably in the orthogonal version directly accessible from the complete active space self consistent field method. Such a reading of the wave function enables one to understand the work of the nondynamical correlation as an enhancement of the weight of the low‐energy VB components, i.e. as a better compromise between the electronic delocalization and the energetic preferences of the atoms. It is suggested that regarding the bond building, the leading dynamical correlation effect may be the dynamical polarization phenomenon. It is shown that most correlation effects do not destroy the bond electron pairs and remain compatible with Lewis' vision. A certain number of free epistemological considerations have been introduced in the development of the argument. © 2006 Wiley Periodicals, Inc. J Comput Chem 2007
A longitudinal study of perceived parental psychological control and psychological well‐being in Chinese adolescents in Hong Kong
Authors: Shek Daniel T. L.
Published: November 2006

On two occasions separated by one year, Chinese adolescents (N = 2,758) responded to instruments measuring their perceived parental psychological control and psychological well‐being, including hopelessness, mastery, life satisfaction, and self‐esteem. Pearson correlation analyses revealed that perceived parental psychological control was concurrently related to adolescent psychological well‐being at Time 1 and Time 2. Multiple regression analyses demonstrated that the relationships between perceived parental psychological control and adolescent psychological well‐being over time were bidirectional in nature. Regarding the differential contribution of paternal and maternal psychological control to adolescent psychological well‐being over time, paternal psychological control at Time 1 predicted changes in adolescent life satisfaction at Time 2, particularly for adolescent girls. On the other hand, maternal psychological control at Time 1 predicted changes in adolescent self‐esteem at Time 2. Relative to those conditions in which one or none of the adolescents' parents was perceived to display high psychological control at Time 1, the psychological well‐being of adolescents at Time 2 was poorer under the condition in which both parents were perceived to display high levels of psychological control at Time 1. The clinical implications of these findings and directions for future research are discussed. © 2006 Wiley Periodicals, Inc. J Clin Psychol 63: 1–22, 2007.
Bipolar disorder: Improving diagnosis and optimizing integrated care
Authors: Culver J. L. , Arnow B. A. , Ketter T. A.
Published: November 2006

Bipolar disorder is a chronic, severe condition commonly causing substantial mortality and psychosocial morbidity. Challenges in recognition can delay the institution of appropriate management, whereas misdiagnosis may initiate pharmacologic interventions that adversely affect the condition's course. Pharmacotherapy remains the foundation of treatment. In addition to efficacy, tolerability is an important consideration in medication choice, particularly for long‐term maintenance because of its impact on adherence. Mood stabilizers are the classic treatments for bipolar disorder. Newer agents such as atypical antipsychotics may offer efficacy and/or tolerability advantages compared with other medications. The role of antidepressants in bipolar disorder remains controversial. Growing evidence indicates that adjunctive psychosocial interventions improve long‐term functioning; consequently, psychologists are becoming increasingly involved in the long‐term care of patients with bipolar disorder. This review seeks to update psychologists and related healthcare professionals on recent advances and the current limitations in the diagnosis and treatment of bipolar disorder. © 2006 Wiley Periodicals, Inc. J Clin Psychol 63: 73–92, 2007.
Examination of the analytic quality of behavioral health randomized clinical trials
Authors: Spring Bonnie , Pagoto Sherry , Knatterud Genell , Kozak Andrea , Hedeker Donald
Published: November 2006

Adoption of evidence‐based practice (EBP) policy has implications for clinicians and researchers alike. In fields that have already adopted EBP, evidence‐based practice guidelines derive from systematic reviews of research evidence. Ultimately, such guidelines serve as tools used by practitioners. Systematic reviews of treatment efficacy and effectiveness reserve their strongest endorsements for treatments that are supported by high‐quality randomized clinical trials (RCTs). It is unknown how well RCTs reported in behavioral science journals fare compared to quality standards set forth in fields that pioneered the evidence‐based movement. We compared analytic quality features of all behavioral health RCTs (n = 73) published in three leading behavioral journals and two leading medical journals between January 2000 and July 2003. A behavioral health trial was operationalized as one employing a behavioral treatment modality to prevent or treat an acute or chronic physical disease or condition. Findings revealed areas of weakness in analytic aspects of the behavioral health RCTs reported in both sets of journals. Weaknesses were more pronounced in behavioral journals. The authors offer recommendations for improving the analytic quality of behavioral health RCTs to ensure that evidence about behavioral treatments is highly weighted in systematic reviews. © 2006 Wiley Periodicals, Inc. J Clin Psychol 63: 53–71, 2007.
Platelet rich plasma (PRP) enhances anabolic gene expression patterns in flexor digitorum superficialis tendons
Authors: Schnabel Lauren V. , Mohammed Hussni O. , Miller Brian J. , McDermott William G. , Jacobson May S. , Santangelo Kelly S. , Fortier Lisa A.
Published: November 2006

Platelet rich plasma (PRP) has recently been investigated for use in tissue regeneration studies that seek to utilize the numerous growth factors released from platelet α‐granules. This study examined gene expression patterns, DNA, and collagen content of equine flexor digitorum superficialis tendon (SDFT) explants cultured in media consisting of PRP and other blood products. Blood and bone marrow aspirate (BMA) were collected from horses and processed to obtain plasma, PRP, and platelet poor plasma (PPP). IGF‐I, TGF‐β1, and PDGF‐BB were quantified in all blood products using ELISA. Tendons were cultured in explant fashion with blood, plasma, PRP, PPP, or BMA at concentrations of 100%, 50%, or 10% in serum‐free DMEM with amino acids. Quantitative RT‐PCR for expression of collagen type I (COL1A1), collagen type III (COL3A1), cartilage oligomeric matrix protein (COMP), decorin, matrix metalloproteinase‐3 (MMP‐3), and matrix metalloproteinase‐13 (MMP‐13) was performed as were DNA and total soluble collagen assays. TGF‐β1 and PDGF‐BB concentrations were higher in PRP compared to all other blood products tested. Tendons cultured in 100% PRP showed enhanced gene expression of the matrix molecules COL1A1, COL3A1, and COMP with no concomitant increase in the catabolic molecules MMP‐3 and MMP‐13. These findings support in vivo investigation of PRP as an autogenous, patient‐side treatment for tendonitis. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 25:230–240, 2007
Binding and localization of recombinant lubricin to articular cartilage surfaces
Authors: Jones Aled R.C. , Gleghorn Jason P. , Hughes Clare E. , Fitz Lori J. , Zollner Richard , Wainwright Shane D. , Caterson Bruce , Morris Elisabeth A. , Bonassar Lawrence J. , Flannery Carl R.
Published: November 2006

Lubricin is a secreted, cytoprotective glycoprotein that contributes to the essential boundary lubrication mechanisms necessary for maintaining low friction levels at articular cartilage surfaces. Diminishment of lubricin function is thereby implicated as an adverse contributing factor in degenerative joint diseases such as osteoarthritis. Lubricin occurs as a soluble component of synovial fluid, and is synthesized and localized in the superficial layer of articular cartilage (and thus has also been described as “superficial zone protein”, or SZP); however, defined interactions responsible for lubricin retention at this site are not well characterized. In the current studies, we identified molecular determinants that enable lubricin to effectively bind to articular cartilage surfaces. Efficient and specific binding to the superficial zone was observed for synovial lubricin, as well as for recombinant full‐length lubricin and a protein construct comprising the lubricin C‐terminal (hemopexin‐like) domain (LUB‐C, encoded by exons 7–12). A construct representing the N‐terminal region of lubricin (LUB‐N, encoded by exons 2–5) exhibited no appreciable cartilage‐binding ability, but displayed the capacity to dimerize, and thus potentially influence lubricin aggregation. Disulfide bond disruption significantly attenuated recombinant lubricin and LUB‐C binding to cartilage surfaces, demonstrating a requirement for protein secondary structure in facilitating the appropriate localization of lubricin at relevant tissue interfaces. These findings help identify additional key attributes contributing to lubricin functionality, which would be expected to be instrumental in maintaining joint homeostasis. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res
Physico‐chemical and functional properties of proteins from green mussel (Perna viridis) during ice storage
Authors: Binsi PK , Shamasundar BA , Dileep AO
Published: November 2006

The effect of ice storage on the properties of proteins from green mussel (Perna viridis) has been investigated. Ice storage of green mussel for a period of 19 days revealed a marginal increase in moisture and decrease in total nitrogen content. There was significant reduction (P < 0.05) in non‐protein nitrogen content and calcium activated adenosine triphosphatase enzyme activity. The solubility of the total proteins in high ionic strength buffer decreased marginally. The ice storage of green mussel had a significant effect on association‐dissociation/denaturation phenomenon of proteins as revealed by gel filtration profile, reduced viscosity values and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) pattern. The dynamic viscoelastic behaviour of green mussel meat in the temperature range of 30–90 °C revealed higher storage modulus (G′) values at a later part of ice storage. The emulsion capacity of green mussel did not show significant variation (P < 0.05) during ice storage. Copyright © 2006 Society of Chemical Industry
Importance of instrumental and sensory analysis in the assessment of oxidative deterioration of omega‐3 long‐chain polyunsaturated fatty acid‐rich foods
Authors: Kolanowski Wojciech , Jaworska Danuta , Weißbrodt Jenny
Published: November 2006

Omega‐3 long‐chain polyunsaturated fatty acids (LC PUFA) positively influence human health. Their main dietary source is fish, especially fish oil. Owing to low fish consumption in many Western countries the average intake of omega‐3 LC PUFA is below the recommended level. This raises interest in diet supplementation and food enrichment with fish oil. However, due to a high degree of unsaturation fish oil is extremely susceptible to oxidation. Oxidation of fish oil increases when added to food products, which may be enhanced by some antioxidants, under certain conditions. For quality control of omega‐3 LC PUFA‐containing foods adequate and combined methods of oxidation assessment should be used, beginning from the raw material and continuing during processing, storage and distribution. To achieve this goal correlation of instrumental and sensory methods with multivariate data analysis may give the best results. In this paper problems of oxidation of fish oil and fish oil‐containing foods, as well as methods for its assessment, are reviewed. Copyright © 2006 Society of Chemical Industry
Segmenting voters online: the youth vote
Authors: Chicksand Lorna , Carrigan Marylyn
Published: November 2006

This paper will build on previous work that has examined the impact of the Internet on political processes, such as the work of Gibson and Ward (1998, 2003) and Dermody and Wring (2001). Most of this work has focused on developing frameworks with which to analyse the ‘effectiveness’ of these websites. Our approach complements this earlier work by utilizing an interpretive methodology (Thompson, 1996) to gain a deeper insight into end‐users perceptions of political parties' websites. This paper will discuss the activities of young people on the Net and outline some of the reasons why political parties' websites are failing to attract a younger audience. A consideration of the technical factors that make a ‘good’ website will be followed by in‐depth interviews with young people to elicit their views and experiences of political parties' websites. At a time when voter apathy is at an all time low, this study is especially relevant.

Copyright © 2006 John Wiley & Sons, Ltd.
Engaging the media in diabetes prevention in Sri Lanka
Authors: Gunathilake W , Kulasinghe Rajendra , Siriwardana A , Hettiarchchi K , Thomson GA , Fernando DJS
Published: November 2006

Reaching entire populations with information relevant to the prevention of diabetes and its complications is a challenge wherever it is faced. However, given the complex issues of literacy, multi‐ethnic communities, language differences and cultural variations, these problems are compounded in developing nations. In this article we describe a campaign co‐funded by the World Diabetes Foundation, the Endocrine and Metabolic Diseases Trust of Sri Lanka, and the charitable Sri Lanka Education Fund held in Trust at Sherwood Forest Hospitals NHS Trust. This campaign has sought to reach a large part of the population of Sri Lanka with education intended to reduce the present explosion of diabetes and its complications in this developing nation. Copyright © 2006 John Wiley & Sons.
Training people to live healthier lives and teach others to do the same
Authors: Guthreau C , Castañeda A , Alen MC
Published: November 2006

Diabetes education is the cornerstone of effective self‐care. People with diabetes must understand the physiology of their disease, as well as the interrelated components of self‐management in order to achieve optimum control and reduce the risk of acute and chronic complications. Unfortunately, health workers often do not have the time nor the training to provide diabetes education in a format that is accessible to all — including the elderly and those with limited literacy.

Poor patient education has contributed to making diabetes the leading cause of death in Mexico. In response, Project HOPE (an international organisation specialising in health education) developed a 24‐hour course in a game‐based, interactive format for people diagnosed with diabetes and for those at risk. Grounded in the philosophy of empowerment, the ‘5 Steps to Self‐Care’ course is imparted over 12 weeks, with weekly homework assignments that reinforce learning as participants share what they learn about diabetes with family and friends. With promising quantitative (A1c) and qualitative (‘well‐being’) indicators, the ‘5 Steps’ course has been transferred via a ‘training of trainers’ model to multidisciplinary teams of health workers in 16 primary care clinics and three community groups serving a region of two million inhabitants outside Mexico City. In addition, the project has spurred a grass‐roots ‘peer education’ initiative, with course graduates serving as role models and educating others in how to prevent, detect and better manage diabetes at the community level. Copyright © 2006 John Wiley & Sons.
Fibrillar structure of self‐assemblies formed from heterocomplementary monomers linked through sextuple hydrogen‐bonding arrays
Authors: Buhler E. , Candau S. J. , Schmidt J. , Talmon Y. , Kolomiets E. , Lehn J.‐M.
Published: November 2006

The nanostructure of the fibrillar supramolecular aggregates generated in decane solutions of homoditopic heterocomplementary monomers forming sextuple hydrogen‐bond‐mediated self‐assemblies was investigated by small‐angle neutron scattering and cryogenic‐temperature transmission electron microscopy. The persistence length (Lp) of the fibrillar aggregates was found to be ∼18 nm, as inferred from combined measurements of the radius of gyration and of the contour length. The values of both the weight‐average molecular weight and the mass per unit length of the fibers suggest that the latter consist of few aggregated monomolecular wires. At T = 25 °C, the formation of branched aggregates occurs around the crossover concentration, C*, between the dilute and semidilute regimes, whereas the classical behavior of equilibrium polymers is observed at T = 65 °C. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 103–115, 2007
Crystallization and crystal structure of poly(ester amide)s derived from L‐tartaric acid
Authors: Regaño Celia , Marín Romina , Alla Abdelilah , Iribarren José I. , De Ilarduya Antxon Martínez , Muñoz‐Guerra Sebastián
Published: November 2006

The crystal structure and crystallization behavior of a series of poly(ester amide)s derived from L‐tartaric acid, 1,6‐hexanediamine, and 6‐amino‐1‐hexanol were examined. The study included aregic polymers containing 5, 10, and 20% of ester groups in addition to the syndioregic polymer containing equal amounts of amide and ester groups. X‐ray diffraction data revealed that all the aregic poly(ester amide)s adopt the same crystal structure as the parent polyamide made of L‐tartaric acid, and 1,6‐hexanediamine. In this structure, chains are slightly compressed and arranged as in the α‐form of nylon 66. Solid‐state nuclear magnetic resonance (NMR) revealed that ester groups are excluded from the crystal phase except for the case of the syndioregic polymer. Isothermal crystallization kinetics was analyzed according to the Avrami theory. Crystallization rates were found to decrease regularly with increasing contents in ester groups and with increasing crystallization temperature. Avrami exponent values close to 2 were found whereas spherulitic morphologies were observed by optical microscopy. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 116–125, 2007
Polymer electrolyte membranes by in situ polymerization of poly(ethylene carbonate‐co‐ethylene oxide) macromonomers in blends with poly(vinylidene fluoride‐co‐hexafluoropropylene)
Authors: Elmér Anette Munch , Jannasch Patric
Published: November 2006

Salt‐containing membranes based on polymethacrylates having poly(ethylene carbonate‐co‐ethylene oxide) side chains, as well as their blends with poly(vinylidene fluoride‐co‐hexafluoropropylene) (PVDF‐HFP), have been studied. Self‐supportive ion conductive membranes were prepared by casting films of methacrylate functional poly(ethylene carbonate‐co‐ethylene oxide) macromonomers containing lithium bis(trifluorosulfonyl)imide (LiTFSI) salt, followed by irradiation with UV‐light to polymerize the methacrylate units in situ. Homogenous electrolyte membranes based on the polymerized macromonomers showed a conductivity of 6.3 × 10−6 S cm−1 at 20 °C. The preparation of polymer blends, by the addition of PVDF‐HFP to the electrolytes, was found to greatly improve the mechanical properties. However, the addition led to an increase of the glass transition temperature (Tg) of the ion conductive phase by ∼5 °C. The conductivity of the blend membranes was thus lower in relation to the corresponding homogeneous polymer electrolytes, and 2.5 × 10−6 S cm−1 was recorded for a membrane containing 10 wt % PVDF‐HFP at 20 °C. Increasing the salt concentration in the blend membranes was found to increase the Tg of the ion conductive component and decrease the propensity for the crystallization of the PVDF‐HFP component. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 79–90, 2007
Photophysical and electroluminescent properties of fluorene‐based binary and ternary donor–acceptor polymer blends
Authors: Wu Wen‐Chung , Lee Wen‐Ya , Pai Chia‐Ling , Chen Wen‐Chang , Tuan Chih‐Shen , Lin Jen‐Lien
Published: November 2006

The photophysical and electroluminescent properties of fluorene‐based polymer blend systems were studied, including blue‐emitting poly[2,7‐(9,9′‐dihexylfluorene)] (PF), green‐emitting poly[2,7‐(9,9′‐dihexylfluorene)‐alt‐5,8‐quinoxaline] (PFQ), yellow‐emitting poly[2,7‐(9,9′‐dihexylfluorene)‐alt‐4,7‐(2,1,3‐benzothiadiazole)] (PFBT), and red‐emitting poly[2,7‐(9,9′‐dihexylfluorene)‐alt‐5,7‐(thieno[3,4‐b]pyrazine)] (PFTP). The binary polymer blends, based on PF blended with 5–25 wt % PFQ or PFBT, were studied to rationalize the effects of the chemical structures and compositions on the intermolecular energy transfer and quantum efficiency. A significant enhancement of quantum efficiency was observed by the blending of a relatively small amount of PFQ or PFBT. Ternary blends composed of PF, PFQ (or PFBT), and PFTP were also studied for potential white‐light‐emitting diodes (WLEDs). The precise composition control of the polymer blends resulted in incomplete Förster energy transfer and emissions from all the components simultaneously. White‐emitting electroluminescence was achieved by the blending of PF with relatively small amounts of the PFQ (or PFBT) and PFTP. The luminance yield and maximum external quantum efficiency of the WLED with the ternary blend FBTTP1 (PF/PFBT/PFTP = 99.65:0.05:0.30 w/w/w) as the emissive layer were 1.89 cd/A and 0.47%, respectively. The electron‐acceptor characteristics, Förster energy transfer, and emissive colors govern the design of WLEDs. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 67–78, 2007
Genome‐based identification and characterization of a putative mucin‐binding protein from the surface of Streptococcus pneumoniae
Authors: Bumbaca Daniela , Littlejohn James E. , Nayakanti Hannah , Lucas Alexander H. , Rigden Daniel J. , Galperin Michael Y. , Jedrzejas Mark J.
Published: November 2006

Streptococcus pneumoniae open reading frame SP1492 encodes a surface protein that contains a novel conserved domain similar to the repeated fragments of mucin‐binding proteins from lactobacilli and lactococci. To investigate the functional role(s) of this protein and its potential adhesive properties, the surface‐exposed region of SP1492 was expressed in Escherichia coli, purified to homogeneity, and partially characterized by biophysical and immunological methods. Circular dichroism and sedimentation measurements confirmed that SP1492 is an all‐β protein that exists in solution as a monomer. The SP1492 protein has been shown to be expressed by S. pneumoniae and was experimentally localized to its surface. The protein functional domain binds to mucins II and III from porcine stomach and to purified submaxillary bovine gland mucin. It appears to be one of the very few unambiguous pneumococcal adhesin molecules known to date. A hypothetical model constructed by ab initio techniques predicts a novel β‐sandwich protein structure. Proteins 2007. © 2006 Wiley‐Liss, Inc.
Molecular dynamics studies of hexamers of amyloid‐β peptide (16–35) and its mutants: Influence of charge states on amyloid formation
Authors: Han Wei , Wu Yun‐Dong
Published: November 2006

To study the early stage of amyloid‐β peptide (Aβ) aggregation, hexamers of the wild‐type (WT) Aβ16–35 and its mutants with amyloid‐like conformations have been studied by molecular dynamics simulations in explicit water for a total time of 1.7 μs. We found that the amyloid‐like structures in the WT oligomers are destabilized by the solvation of ionic D23/K28 residues, which are buried in the fibrils. This means that the desolvation of D23/K28 residues may contribute to the kinetic barrier of aggregation in the early stage. In the E22Q/D23N, D23N/K28Q, and E22Q/D23N/K28Q mutants, hydration becomes much less significant because the mutated residues have neutral amide side‐chains. These amide side‐chains can form linear cross‐strand hydrogen bond chains, or “polar zippers”, if dehydrated. These “polar zippers” increase the stability of the amyloid‐like conformation, reducing the barrier for the early‐stage oligomerization. This is in accord with experimental observations that both the D23/K28 lactamization and the E22Q/D23N mutation promote aggregation. We also found that the E22Q/D23N mutant prefers an amyloid‐like conformation that differs from the one found for WT Aβ. This suggests that different amyloid structures may be formed under different conditions. Proteins 2007. © 2006 Wiley‐Liss, Inc.
Two module factoring techniques
Authors: Calliss F. W. , Cornelius B. J.
Published: November 2006

‘Module factoring’ is the process by which a module can be split into smaller modules each of which performs a distinct task. Two techniques are presented for determining which entities are to be grouped together. The first technique involves analysing a module with respect to its type‐families, while the second technique involves analysing a module's entities with respect to the modules importing the entities. Such techniques have proved useful in the maintenance of large programs.
Harmonizing the development, maintenance and enhancement of application systems
Authors: Ricketts J. A.
Published: November 2006

Renovation is the computer‐aided rejuvenation of existing application systems according to sound engineering principles. It differs from traditional maintenance in that it bridges the gap between ageing and contemporary systems by making both amenable to engineering. For systems that were not engineered originally or that have deteriorated over time, it makes maintenance and enhancement far more tractable.

Information systems engineering is conducted in four ways, three of which renovate existing systems so that the fourth can be conducted with less regard for system age or original technology:

re‐engineering—transformation of bad code into good code, and bad data into good data,

reverse‐engineering—derivation of specifications from good code and data,

transverse‐engineering—transformation of derived specs into designed specs,

forward‐engineering—creation of working systems from designed specs.

The renovation approach to information systems evolution preserves much of the sizeable investment that organizations have in their systems while removing constraints imposed by old technologies. Development, maintenance and enhancement then proceed in harmony because systems are compatible and their definitions are flexible. Renovation should be considered during the formation of information systems architectures and project plans.
Dynamic change management and Ada
Authors: Burns A. , Wellings A. J.
Published: November 2006

Many large real‐time systems are expected to have a long, non‐stop operational life. It cannot, however, be assumed that the code that initially started executing will remain appropriate for the complete lifetime of the system. Indeed it will more likely be the case that the system will be subject to evolutionary change. This can reflect bug fixes, the addition of new functionality, or redeployment of the original code. We introduce in this paper the term Dynamic change management to represent the process of controlling the modification of executing software.

The Ada language will increasingly be used to program non‐stop systems. Unfortunately dynamic modifications to Ada programs appear to be invalid in terms of the Ada Language Reference Manual. This paper discusses dynamic change management within the context of distributed Ada execution. Our intention is not to provide a methodology within which such changes can take place; we believe this to be too difficult at the current time. Rather we wish to provide a focus for discussion of this important future problem area. However, we do offer a useful classification of software components, and suggest how change can be effected—the approach to be taken depending upon the structure of the component being replaced. The flexibility of dynamic change management depends upon the initial granularity of distribution and deployment. We also attempt to define rules for legally changing running Ada programs.

Although this paper focuses on the Ada language, many of the issues are of general concern.
An approach for developing an integrated modelling environment: A case investigation
Authors: Rine David C.
Published: November 2006

Recent research on software development environments (SDE) and computer‐aided software engineering (CASE) have not addressed the issue of multiple environments. This paper presents an approach for developing an integrated modelling environment (IME) that supports the maintenance of software environment models in software engineering. The approach uses the notion of a composite software development environment maintaining multiple software development environments. The composite is specified by analysing and identifying common features from other environments. These other environments include various government‐supported efforts. The idea of a common software development environment may be supported in part by several different international standards or technical approaches (e.g. CAIS, CAIS‐A, PCTE, ALMA/metasystems, object‐oriented systems, and so forth). Some of these ways are outlined in the paper. An analysis of them in case study form is presented.
Towards a model of programmers' cognitive processes in software maintenance: A structural learning theory approach for debugging
Authors: Hale David P. , Haworth Dwight A.
Published: November 2006

No comprehensive model of programmers' cognitive processes in software maintenance exists. As a first step in formulating such a model, a cognitive processes model for application debugging is developed. The new model is grounded on structural learning theory, which integrates both declarative models, such as Brooks's (1983) programmer comprehension model, and procedural knowledge such as Gould's (1975) process model and Vessey's (1986) functional model as components.

The theoretical foundation of structural learning theory as a reference discipline for exploring software maintenance is provided. Not only are the benefits of the theory examined, but criticisms that have been levied are addressed. Based upon these consequences, the use of structural learning theory as applied to software maintenance is instantiated for the software debugging domain—the result is an approach that unites declarative and procedural knowledge. The practical and research implications of the new approach is then discussed.
Window user interfaces and software maintenance
Authors: Yip Stephen W. L. , Robson David J.
Published: November 2006

User interfaces are assuming an increasing importance within the design of a software product. This paper examines the various levels and components of window user interfaces and exposes their impact on software maintenance. It covers window systems, user interface toolkits, user interface management systems (UIMSs), dialogue separation and other user interface development concepts that will lead to more maintainable software. It also examines the research work on the testing of user interface software that is being pursued at the University of Durham.
Measurement of the maintenance process from a demand‐based perspective
Authors: Abran Alain , Nguyenkim Hong
Published: November 2006

While various figures have been published on the workload distribution of maintenance activities, this information is at best indicative of management perceptions, most of it originating from surveys, and almost none based on actual data. The reason for such a lack of published data is very simple: the industry does not measure or collect maintenance‐type data in a timely and accurate fashion. This article presents empirical data from a two‐year measurement effort in the maintenance environment of a Canadian financial institution. The findings reported here are based on a daily data‐collection process including 2152 work requests, which required 11 332 days to complete.

Based on the supply/demand paradigm, maintenance data have been collected and analysed to investigate the basis of productivity analyses through such concepts as the product group, the product mix and the product mix changes on the demand side, as well as resource allocation by product classification and quarterly and yearly distribution changes. This paper includes a discussion on the measurement program implemented, and illustrates how insights into the maintenance process are gained through various measurements. The paper also presents hard data on the demand side and on the supply side of the maintenance process, as well as an analysis of the data collected. The findings reported are part of a larger measurement program introduced to manage the maintenance area in the same way as any other business unit.
Software maintenance characteristics and effective management
Authors: Chapin Ned
Published: November 2006

This statistical study examines management effectiveness and its relation to software maintenance. The findings include that low‐level managers in software maintenance who see their organizations as well managed also see their organizations as having a constellation of software maintenance characteristics. Compared to equivalent managers in other organizations, that perception includes doing less corrective maintenance and less new development, but doing more enhancement work on systems. It includes doing software maintenance with staff having a lower average experience level, on programs which commonly are bigger. It includes a lower maintenance backlog per maintenance person. The general picture is that effective management in the organization is more associated with relatively trouble‐free systems, more often being, by choice, enhanced, rather than it is associated with meeting new and changed organizational needs by developing new systems.
Abstracting a specification from code
Authors: Ward Martin
Published: November 2006

Much of the work on developing program transformation systems has concentrated on systems to assist in program development. However, the four separate surveys carried out between 1977 and 1990 (Foster and Kiekuth, 1990; Lientz and Swanson, 1980; Morton, 1988; Nosek and Palvia, 1990), summarized in Foster (1991), show that between 40% and 60% of all commercial software effort is devoted to software maintenance rather than the development of new systems. In this paper we describe a joint project between the University of Durham and CSM Ltd to develop a method and tool for reverse‐engineering and software maintenance based on program transformation theory. We present an example which illustrates how such a tool can extract a high‐level abstract specification from the low‐level source code of a program by a process of formal program transformation based on a theory of program equivalence (Ward, 1989a). All the code‐level reverse‐engineering of the example program was carried out on the prototype tool with the resulting code pasted directly into the paper.
Abstraction refinement: A model of software evolution
Authors: Keller Benjamin J. , Nance Richard E.
Published: November 2006

A model of the software evolution process, called the Abstraction Refinement Model, is described. The model has three components: descriptions of the software system, a pre‐order of relative correctness between system descriptions, and transformations between the system descriptions. Using a non‐deterministic language as the collection of system descriptions, the collection of equivalence classes under the abstraction order forms a distributive join‐semilattice. This algebraic structure enables the partitioning of the language into narrow‐spectrum sub‐languages on which the transformations are defined.

The algebraic structure of the model is interpreted to represent software evolution as a sequence of transformations on system descriptions. Both development and maintenance are characterized by forward and reverse transformations, with development being primarily forward‐engineering and maintenance balanced between forward‐ and reverse‐engineering.

This interpretation is instructive regarding maintenance. Three levels of methodological sophistication are shown by the three representations of maintenance possible in the model. These approaches underscore the need for a maintenance methodology which must account for the completeness of the system documentation. Methodologies should then include reverse‐engineering to contend with the information loss problem from development. A result is that only two types of reverse‐engineering paths are possible in the model.
Data linkage maps
Authors: Neil Martin , Bache Richard
Published: November 2006

Most work in software metrics has been aimed at measuring the quality or cost of software. This paper gives an example of how metrics may be used to give information about how the software system is organized, specifically the data linkage between procedures in the source code. The data linkage measures capture how closely procedures are bound together by data flowing between them. The paper shows how data linkage within a program can be represented in a diagrammatic form. This approach makes use of multivariate statistics and is applied to two examples. Results are then compared with the authors' intuitions of how the example programs are organized. This approach could be used as an automatic aid to maintainers.
Resolving the software maintenance paradox
Authors: Blum Bruce I.
Published: November 2006

This paper explores the apparent paradox that, although performance improves with experience, the maintenance of a software system becomes more difficult as experience with it accumulates. It is asserted that this phenomenon is a side effect of the environment used to maintain the software. A decade of experience with a large and complex clinical information system is summarized to demonstrate that software maintenance may be inherently less difficult than original development. It is shown that a highly integrated, million‐line, operational system, used in life‐threatening situations, has been maintained effectively by a staff of six. During the past five years, the size of the system increased by 167%. In addition to maintaining a growing number of programs, the staff produced new programs at a rate of 0.64 programs per effort‐day. Moreover, the case study also demonstrates that this level of performance can be transported to other sites. The paper concludes with some observations regarding changes to the software process that will resolve the paradox.
An empirical study of software maintenance tasks
Authors: Jørgensen Magne
Published: November 2006

An empirical study of software maintenance tasks was carried out in a large Norwegian organization in the period 1992–93. More than one hundred randomly selected maintenance tasks were studied through interviews with the maintainers performing the tasks immediately before they started the tasks and immediately after they had completed the tasks. The collected data is used to develop distributions and to test 33 hypotheses about software maintenance. The findings from the study indicate, for example, that

Application system documentation plays only a minor role as maintenance information source.

The maintenance productivity, measured in LOC/effort, is predicted by the size of the task and type of change in the source code, but seems rather independent of language level, maintainer experience, application age and application size.

There is an economy of scale for software maintenance tasks.

The type of programming language does not correlate with proportion of unexpected maintenance problems, task complexity or task size.

The proportion of corrective maintenance decreases with increasing age of the application.
Software reconnaissance: Mapping program features to code
Authors: Wilde Norman , Scully Michael C.
Published: November 2006

Maintainers of old code often need to discover where particular program features are implemented. This paper presents a method, called ‘software reconnaissance’ for answering this question through an analysis of the execution of different test cases. The method is quite easy to implement, requiring only a test coverage monitor, some simple tools, and a surprisingly small number of test cases.

A statistical case study is presented that shows the kind of results that can be obtained on a typical medium‐sized program. The method seems to be effective in identifying a small number of code components that are unique to a particular program feature, though it may not find all components that make up the feature's delocalized plan. A small protocol case study shows that professional programmers can learn to use the method quickly and can use the information that it produces.

Software reconnaissance may be a simple but useful addition to the maintainer's tool kit in that it provides starting points for understanding a large program and a way of recovering some requirements traceability information from old code. For the researcher, it also provides a novel functionality ‘view’ of software that maps features to program components at different levels of precision.
Maintenance management: From product to process
Authors: Middleton Peter
Published: November 2006

This paper is concerned with just‐in‐time (JIT) manufacturing techniques and how they can be applied to the management of software maintenance. Traditional maintenance methods focus on the change to be made or the defect to be fixed. Their aim is to get the product working as quickly as possible. This paper argues that this approach of pushing work through the maintenance system is flawed. The experience of the manufacturing industries which have global competitors, is that focusing only on results does not win. An alternative is to concentrate on the process of software maintenance. This paper reports on initial experiments with two teams of programmers using JIT techniques for maintaining software. The purpose was to see if JIT could produce benefits when applied to this knowledge‐intensive and unpredictable task. If there is a software maintenance process, then JIT may be a way to optimize the functioning of this process. JIT requires that fault fixes or changes to the software are pulled, rather than pushed, through the maintenance process. A functioning JIT process gives immediate information on the quality of the process because programmers return any work which is not correct.

The conclusion is that JIT approaches can work and do improve the quality of the maintenance done. The key impediments to using JIT in maintenance are the changes it requires in the way people work and the requirement for a different focus in the management of software maintenance.
Logic programming and compiler writing
Authors: Warren David H. D.
Published: November 2006

The concept of ‘logic programming’, and its practical application in the programming language Prolog, are explained from first principles. The ideas are illustrated by describing in detail one sizable Prolog program which implements a simple compiler. The advantages and practicability of using Prolog for ‘real’ compiler implementation are discussed.
Problems of integrity and distributed databases
Authors: Shave M. J. R.
Published: November 2006

A relational model of a small distributed database is used to illustrate problems of consistency and integrity with specific reference to distributed systems, and to discuss methods for their solution. It is shown that some limitation may be necessary on the freedom to make modifications on a purely local basis, and that questions of time consistency due to the network have a partial but limiting solution.
An analysis of Pascal programs in compiler writing
Authors: Shimasaki Masaaki , Fukaya Shigeru , Ikeda Katsuo , Kiyono Takeshi
Published: November 2006

A method and results of static and dynamic analysis of Pascal programs are described. In order to investigate characteristics of large systems programs developed by the stepwise refinement programming approach and written in Pascal, several Pascal compilers written in Pascal were analysed from both static and dynamic points of view. As a main conclusion, procedures play an important role in the stepwise refinement approach and implementors of a compiler and designers of high level language machines for Pascal‐like languages should pay careful attention to this point. The set data structure is one of the characteristics of the Pascal language and statistics of set operations are also described.
Implementation of concurrent Pascal on LSI—11
Authors: Mattsson Sven Erik
Published: November 2006

This paper considers the moving of the implementation of Concurrent Pascal for the PDP‐11/45 computer to the LSI‐11 computer. The resulting implementation for the LSI‐11 computer is also discussed and described.
Comments on an error‐recovery scheme by Hartmann
Authors: Pemberton Steven
Published: November 2006

A. C. Hartmann has described what is probably the definitive error‐recovery method for recursive‐descent parsers. Some comments are made on possible improvements, and an error is corrected.