bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrochemical Methods of Determining the Corrosivity of Steel in Concrete
Authors: Berke NS , Hicks MC
Published: March 2009

Steel-reinforced concrete is used throughout the world in the construction of bridges, marine structures, parking garages, and buildings. The alkaline environment of the concrete protects the steel from corrosion; however, this protective environment can be disrupted due to the migration of chloride ions to the steel and/or to carbonation of the concrete. In this paper several electrochemical techniques that can be used to determine and predict the corrosion of steel in concrete are described. Further, it is shown how these techniques can be used to show the effectiveness of corrosion inhibitors and other modifications to the concrete mixture on corrosion control.

Solution testing in calcium hydroxide and in sodium/potassium hydroxide pore water solutions can be used to determine corrosion mechanisms and the effectiveness of inhibitors when chloride is present. The use of cyclic polarization in these solutions to determine the effects of chloride and calcium nitrite is discussed.

Corrosion testing of steel in concrete provides more direct evidence of the effect of the concrete mix design on corrosion performance. Three techniques are quite common in this laboratory and in others. They are polarization resistance, electrochemical impedance, and the measurement of the macrocell corrosion between two layers of bars. The use of these techniques is discussed, and several examples of their use and comparison to visual attack of the steel are given. The techniques, as used, correlate very well with the observed corrosion damage on the embedded steel.

Because polarization resistance and electrochemical impedance are nondestructive, they can be used to monitor the corrosion rates of steel in concrete, whereas mass loss or visual observation require destruction of the concrete to observe the bar. The use of these techniques to monitor the long-term behavior of steel in concrete is demonstrated.
Sensitivity analysis of pesticides contaminating groundwater by applying probability and transport methods
Authors: Zhang Pengxin , Aagaard Per , Nadim Farrokh , Gottschalk Lars , Haarstad Ketil
Published: March 2009

The use of pesticides is a potential threat to local groundwater. Once groundwater is contaminated, it is very difficult to clean. Thus, it is of importance to assess the risk of contaminating local groundwater at an early stage when pesticides are found in soils. This knowledge will also help in remediation strategies. Traditional methods of deterministic analysis cannot explicitly account for the sometimes large uncertainties that exist at this stage in the work, whereas probabilistic analyses are better suited for dealing with these problems. In this paper, we have combined contaminant transport with a 1st-order reliability approach. Pesticide concentrations in soil have been studied to estimate the probability of failure—that is, of pesticides exceeding established critical levels in groundwater. Results indict that failure probability increases rapidly within a certain range of pesticide concentrations in soil for different critical levels. In given aquifer conditions and contaminants, probabilities of contaminants exceeding particular critical levels can easily be obtained according to various water usage scenarios. The distribution of importance factors among variables indicates the contribution their relative weights make to the failure probability. Hence, authorities can easily form sensitivity factors to take action and reduce the risk of contaminating the groundwater.
Identifying Landmines by Incorporating Measurement Uncertainties into EMIS Library and Decision Threshold
Authors: Zeng Zhaofa , Huang Haoping , Liu Fengshan
Published: March 2009

Determining decision thresholds to separate landmines from clutter is a critical but difficult task in landmine identification procedures because such thresholds depend upon local geology, distribution of landmines and clutter, data acquisition, and cultural and environmental noise at a given landmine cleanup site. We describe a learn-as-you-go approach to build an electromagnetic induction spectroscopy (EMIS) library and decision thresholds for humanitarian demining operations, which include uncertainties regarding the target∕sensor position and orientation, target depth, geological and environmental noise, and measurement errors. This approach is then simulated mathematically using electromagnetic (EM) data obtained over the calibration plot at a test site. The resulting EMIS library and thresholds are tested on the EM data colleted in the test squares at the same site. Apparent conductivity converted from the data is used as a detector function, and both spectral shape and amplitude response are used quantitatively in the matching algorithm. Our results show that the detection rates are increased from 92% to 98% and identification rates from 76.2% to 95%, and the false alarm rate is reduced from 13% to 5%, compared with the previous results obtained from the same dataset.
Evaluation of diagnosis accuracy in minimal carious lesions
Authors: Zivojinovic Vesna , Markovic Dejan
Published: March 2009

The aim of this study was to assess the accuracy of visual-tactile inspection (VTI) and laser fluorescence (LF) in detection of initial carious lesions on occlusal surfaces. Total of 120 premolars and molars, without any macroscopic cavitation on occlusal surface, planed to be extracted for orthodontic, prosthetic or surgical reasons, were included in this study. The agreement between histological diagnosis and diagnostic and treatment decisions of evaluated methods was assessed. The obtained results showed that specificities and sensitivities were for VTI=83 and 36%, and LF-77 and 96%. The percentage of correct treatment decisions were: VTI=54% and LF-80%. Diagnosing caries was significantly dependent on the fissure morphology and LF showed statistically better results than VTI. It can be concluded that laser fluorescence was significantly efficient and more accurate in diagnosing initial carious lesions on occlusal surfaces.
Evaluation of apical obturation quality of diferent endodontic materials
Authors: Matovic Ivan
Published: March 2009

The aim of this study was to determine the quality of apical obturation of different endodontic materials, using the colored solutions method. As a material, we used 40 single-rooted teeth, extracted from persons of different ages and sex. We did the root-canals preparation using standard endodontical procedure with KERR reamers and files. After we had prepared root canals, we filled them up, using the lentulo-spirals and Gutta-percha points. For the opturation, we used four different endodontic materials a?26, Ketac Endo, Endomethasone and Sealapex. Under the in vitro conditions, we checked the quality of the apical opturation, using the linear dye leakage method and 2 % methylen blue solution. According to results, we can conclude that endodontic materials AH26 (x=1, 37) and Ketac Endo (x=1,17) showed a significantly lower degree of apical leakage than Endomethasone (x=2. 51) and Sealapex (x=3,25).
Analysis of protein compounds in old persons whole saliva with parodontal diseases
Authors: Mukovic Silvija , Zelic Obrad , Andjelski Biljana
Published: March 2009

The purpose of this work was to determine the protein composition of whole saliva in 50 year-old patients an d older with manifested and terminal stages of periodontal disease, in correlation with control group of young healthy persons. Experimental and control group consisted of 30 patients. The periodontal status was determinate by using appropriate periodontal index (Sillness-Loe). Investigations were led by electrophoretic method on aragose gel which was used as a routine method for investigation of human serum proteins. Investigating in very alkaline conditions (pH-H) as well as acid conditions (pH=5.9) resulted in separating alkaline and acid glycoprotein fractions in whole saliva. Results showed that there were more separated fractions within basic conditions than within acid conditions. The fraction identification was done by using relative molecule mass determination method by Weber and Osborne. Molecule mass fractions at basic conditions in comparison with the healthy sample (Sz) indicated the destruction of big molecular weight alkaline proteins as well as a significant presence of acid fractions, of little molecule masses up to 60 000 (St), consequences due to aging processes in human organism. It can be concluded that changes in protein composition of whole saliva could point out to the direction and development of periodontal disease as well as changes concerning aging of human organism.
Degree of the residual alveolar ridge resorption registrated by ortopantomograms among immediate and classic complete denture users
Authors: Markovic Dubravka , Krstic Mirjana , Djuric Milanko , Brkanic Tatjana
Published: March 2009

Degree of residual ridge loss is influenced by sistemic phactors, but during the first phase after extraction local phactors are dominant. Patohistological changes of alveolar processus of jaws show the possibility of negative influence of complete dentures on support tissue. In this study, on the chosen sample, the degree of alveolar ridge loss was measured in the group of immediate complete denture users (30 patients) and classical complete denture users ( 30 patients).Height of residual alveolar ridge was measured on ortopantomograms. Localization of referent points proportion was used because of neutralization of shadow distorsion (five in maxilla and five in mandibula). The first ortopantomogram was made at the time of delivering dentures, and the second one six months later. The final measurement of alveolar ridge height is bigger in the group with classical dentures. The reduction degree of residual alveolar ridge is bigger in the group of immediate complete denture users in the first six months.
Biocompatibility assessment of glas ionomer cement: Test of cytotoxicity
Authors: Markovic Dejan
Published: March 2009

Evaluation o f cytotoxicity is a first step in assessment of dental materials biocompatibility. Necessity for unique criteria in researches resulted in international standard methodology (ISO). The aim of this study was to assess the cytotoxicity of four restorative materials (three glas ionomer cements and one composite material) and to define adventages and disadventages of common ISO methodology for evaluation of this aspect of dental materials biocompatibility. Research was designed according to ISO/TC 106/1995 and ISO/ 10993-5/1994 methodology. Materials used in this investigation were Fuji IILC (GC), Vitiemer (3M), Ionosit fill (DMG-Hamburg), Luxat (DMG-Hamburg). Evaluation of cytotoxicity was carried out on standardized Human Diploid Cell Lung WI-38. Obtained results showed expressive cytotoxic effect of all investigated materials without statisticaly significant difference. Estimation of material biocompatibility and assessment of obtained results can be made only after establishment of correlation with test results. Common ISO methodology is simple for conductance and reproduction, and use of cell cultures in researches is painless, cost effective and without moral or ethical dilemma.
Gingival hyperplasia induced by Nifedipine: case report
Authors: Djuric Milanko , Picuric Ivana
Published: March 2009

Nifedipine, a calcium channel blocker, is commonly used in the treatment of cardiovascular disorders. In this paper a case report is presented which describes a patient medicated with Nifedipine for angina pectoris and arterial hypertension, who developed severe gingival hyperplasia.
Dental treatment of oral complications during radiation therapy of head and neck cancer
Authors: Dakovic Dragana , Ljuskovic Besir , Jovic Nebojsa , Mileusnic Dusan
Published: March 2009

Radiation therapy is often used as primary or adjuvant therapy for malignancy of the oropharyngeal region. Inflammatory changes of the oral mucosa resulting from the direct effect of radiation therapy, are defined as Radiation Mucositis (RM). As a consequence of irradiation, patients have xerostomia, pain, difficulty in chewing and swallowing, dental caries, oral microbial changes, chronic esophagitis, periodontitis, osteoradionecrosis. To eliminate or decrease discomfort in oral cavity, the use of various mouth rinses is recommended for compromised patients. These solutions should reduce pain, promote reepithelialization of soft tissue lesions, normalize the pH of oral fluids. They should be nontoxic, and to have acceptable taste. In the modern practice of head and neck oncology, dentists are essential members of the team. Their contribution is essential in improvement of the patients' quality of life.
T-scan II occlusal analysis in restorative dentistry
Authors: Lazic Vojkan , Zivkovic Slavoljub
Published: March 2009

The comparison of accufilm markings and computerized T-Scan II force plots of restorations and occlusal interferences in intercuspal position of the lower jaw, before and after occlusal adjustment showed a great improvement in force distribution, balance of occlusal forces and evenness of the right and left side. The computer analysis through T-Scan II system help us to clearly understand what those well balanced occlusal contacts and force distribution really mean for the proper restorative occlusal therapy.
Cryptography
Authors: Katz Jonathan
Published: March 2009

This article focuses on applications of cryptography to the problem of secure communication; in this context, secure refers to both secrecy and message integrity. The article describes appropriate techniques for achieving these goals in both the private‐key and public‐key settings.
Robust Resource Allocation in Heterogeneous Parallel and Distributed Computing Systems
Authors: Smith Jay , Siegel Howard Jay , Maciejewski Anthony A.
Published: March 2009

Resource allocation in heterogeneous parallel and distributed computing is the process of assigning tasks to computers for execution such that some performance objective is optimized. In this article, the robustness of resource allocations in both static and dynamic environments is evaluated.
Functional Programming
Authors: Chitil Olaf
Published: March 2009

Functional programming is a programming paradigm like object‐oriented programming and logic programming. Functional programming comprises both a specific programming style and a class of programming languages that encourage and support this programming style. Functional programming enables the programmer to describe an algorithm on a high level, in terms of the problem domain, without having to deal with machine‐related details. A program is constructed from functions that only map inputs to outputs, without any other effect on the program state. Thus, a function will always return the same output, regardless of when and in which context the function is used. These functions provide clear interfaces, separate concerns, and are easy to reuse. A small and simple set of highly orthogonal language constructs assists in writing modular programs.
Graphical User Interfaces
Authors: Stadler Alexandra , Lorenz Haik
Published: March 2009

A graphical user interface (GUI) is the visible part of a system that you see, hear, and feel. All interaction between user and system is based on the GUI, which hides other parts and their functions. Interaction takes place in different forms, such as menu selection, form fill‐ins, or direct manipulation. From their beginning in the early 1960s, the ideas behind GUIs have not changed significantly. Still, we use the desktop metaphor or WIMP approach developed around 1970 for standard workstations. Progress mainly focuses on technology and graphical representations, which translates to improved efficiency of GUIs.

After briefly listing the most important events in GUI history, this article gives an introduction to basic concepts behind GUIs, which include metaphors, conceptual models, interaction styles, and main elements. Furthermore, it describes GUIs as they are used in current computer systems, and it covers design issues and implementation aspects. Design is discussed from a usability point of view including rules, style guides, and international norms. This part is completed by approaches to usability testing. The implementation part briefly outlines common programming practices for GUIs and lists ready‐to‐use frameworks for GUI implementation. The article closes with highlighting some advanced GUI approaches for nonstandard tasks and environments.
Distributed Project Management
Authors: Prikladnicki Rafael , Audy Jorge Luis Nicolas
Published: March 2009

Software development involves teamwork and a lot of communication. It seems rational to put all your team members in one place, encourage them to share objectives, and let the project run. But the movement toward globally distributed software development is changing the way projects are planned, developed, tested, and delivered to customers. Is this article, we present the concepts involved in distributed software development, and particularly the challenges of distributed project management, that is, when a project manager has to manage a distributed development team. The article is focused on a specific type of distributed development, when a company transfers work to one or more subsidiaries of the same company, and the subsidiaries are geographically distributed in multiple locations.
Operating Systems: A Business Perspective
Authors: Bajgoric Nijaz
Published: March 2009

The proliferation of e‐business applications and enterprise information systems that use several models of client‐server architectures has created the need for a common business perspective of operating systems, particularly server operating systems.

In this article, we propose a framework for studying operating systems for business systems within the concepts of business continuity and continuous computing tehnologies that can be used for enhancing business continuity. The framework first identifies the main attributes of continuous computing and then locates the role of server operating systems and the so‐called server operating environment. Server operating systems are expected to have a powerful “business dimension” as a set of features that relate to high availability, reliability, and scalability ratios as today's business has to be resilient and operational on an “always‐on” basis. Servers and server operating systems that provide zero downtime or 100% uptime or a solution that is “near it” are of extreme importance for many businesses today.

This article considers server operating systems in a broader sense as a core component of a server operating environment that employs several information technologies in the form of continuous computing technologies for enhancing the levels of continuous computing and business continuity. In addition, the article presents a framework for the selection of enterprise servers and a server operation system from a business continuity perspective.
Software Reusability
Authors: Kim Soo Dong
Published: March 2009

As a key strategy to overcome the software crisis,
software reuse
is an attempt to reuse software assets in building high‐quality software in a cost‐efficient way. Software reuse technology has been evolved through generations of programming paradigms. In this article, we first define seven dimensions for software reusability:
abstraction, interface visibility, interface role, granularity, adaptability, bind persistency
, and
acquisition
. With these, we observe the evolution of reuse technology. For each programming paradigm, its key reuse constructs are discussed, and a technical assessment for its reusability is given. In addition, we observe the reusability of design patterns and architectural styles. Finally, we derive key trends in software reusability from the technical assessments on reuse technologies and their evolution.
Time‐Sharing Systems
Authors: Sodan Angela C.
Published: March 2009

The article introduces the concept of time sharing and presents its history and different areas of application. Then, the virtualization of the machine as necessary for time sharing is explained in more detail, discussing the affected resources of memory, disk, network, and—most importantly—the (CPU). Metrics and necessary hardware support follow this discussion. Finally, more advanced areas of time sharing are presented: real‐time systems, multi‐CPU/multicore/multithreaded environments, and dedicated HPC resources. The article concludes with the extraction of the most important design decisions and the current trends.
Computability
Authors: Cooper S. Barry
Published: March 2009

The history of the computer is unusual, in that the theory in the form of the Universal Turing Machine preceded its physical embodiment by around 10 years. Computability as a research area grew out of the work of pioneers such as Alan Turing in the 1930s, and it is still very much defined by the interests of Turing, with his keen curiosity about patterns and underlying theory, but theory firmly tied to a real‐world context. This article reviews some main contemporary research directions with new developments strongly featured. A particular focus is the development and investigation of deep and mathematically interesting computational structures, which tell us more about what can and cannot be computed. Turing's notion of an oracle computing machine provides a natural model of computationally complex environments, structuring information, and hence the real world, in remarkably informative ways. Other important topics include randomness and computability of structures. A useful reading list is given.
Statistical Methods for Target Tracking
Authors: Maskell Simon
Published: March 2009

Tracking is the algorithmic process of updating of a perception of the time‐evolving state of the stochastic world as a noisy stream of data is received. To do this, one needs to define statistical models for the evolution of the state and the relationship between the state and the data. The definition of the state and the stream are problem specific. Indeed, these definitions define the problem that a specific tracking algorithm is tackling. An algorithmic implementation of an exact solution to this mathematical problem can be defined in cases when the models have certain mathematical properties. An example is the Kalman filter. However, often the models require approximation: This article reviews both exact and approximate solutions based on the Kalman filter and particle filter. It then goes on to describe the use of multihypothesis techniques and multitarget tracking algorithms. Finally, the mean‐shift tracking paradigm, which is popular in the computer vision literature, is discussed.
Autonomous Surveillance Systems
Authors: Everett Bart
Published: March 2009

The U.S. Department of Defense (DoD) defines surveillance as “the systematic observation of aerospace, surface, or subsurface areas, places, persons, or things, by visual, aural, electronic, photographic, or other means”. Persistent surveillance implies the ability of such information gathering systems to linger on demand in a region of interest, to facilitate prediction of an adversary's behavior. Unmanned systems have long been perceived as well suited to the surveillance role because they can bring various sensors to bear for long periods of time without exposing humans to the inherent dangers involved.

Television‐equipped unmanned air vehicles (UAVs), for example, which first appeared during Worldwar II in the form of teleoperated assault drones, were employed effectively in aerial surveillance roles during the Vietnam War. Today, more sophisticated autonomous UAVs, such as the CIA‐developedPredatorand the U.S. Air ForceGlobal Hawk, are used routinely to seek out and shadow insurgent activity in several hot spots around the world. This article will focus on lesser‐known surveillance applications for unmanned ground vehicles (UGVs) in both indoor and outdoor environments, with applicable examples of work performed by the Unmanned Systems Branch at the Space and Naval Warfare Systems Center (SSC) San Diego.
Information Systems and Computer Science and Engineering
Authors: Korukonda Appa Rao
Published: March 2009

Information systems, computer science, and engineering are distinct but related disciplines, each with a focus of its own (the term engineering is used here to refer to computer engineering and software engineering). This focus has been changing with technological trends of the times, and as a result, the boundaries of these discipline always have been fuzzy and in a state of constant evolution.

This article discusses the current state of the disciplines in the context of their technological and historical evolution. Links among available technologies, accepted definitions of the discipline, professional practices, and paradigm changes are sketched out with the aid of examples. Models, methodologies, and areas of primary concern for each of the disciplines are presented from the academic and the practitioner perspectives. Ideological controversies and areas of ambiguity are sketched out in mapping the terrain of each field.

It is posited that foundational questions as well as claims and counterclaims that concern domain boundaries have been endemic to each of the disciplines. It is argued that although to some extent, virtually all disciplines evolve over time, one must take explicit cognizance of the fluid nature of the disciplinary boundaries and foundational questions when it comes to information systems (IS), computer science (CS), or computer/software engineering. Although this state of flux continues to plague all of these disciplines, it also offers enormous opportunities for growth and interdisciplinary collaboration.

Potential future directions and challenges are presented.
Computing Pre‐University: Challenges in K‐12 Computing Education
Authors: Haberman Bruria
Published: March 2009

Many educators agree that computer science provides the knowledge and skills foundation for contemporary technological advances; thus, learning computing, and in particular computer science, is essential for enhancing IT fluency. Specifically, the instructional design should concentrate on educating a proficient graduate who would master IT on three orthogonal axes—concepts(basic ideas that underlie the domain),capabilities(related to problem solving), andskills(related to IT literacy).

One main goal is to assist students in bridging the gap between using and understanding computers. Another important goal is to make students realize the benefits of studying computer science, since it may serve as an entry point for other disciplines. Computing education should be planned for and adapted accordingly to various populations: (a) all students, especially those who wish to obtain expertise in the field, and (b) scientists of tomorrow.
Non‐volatile Ferroelectric Poly(vinylidene fluoride‐co‐trifluoroethylene) Memory Based on a Single‐Crystalline Tri‐isopropylsilylethynyl Pentacene Field‐Effect Transistor
Authors: Kang Seok Ju , Bae Insung , Park Youn Jung , Park Tae Ho , Sung Jinwoo , Yoon Sung Cheol , Kim Kyung Hwan , Choi Dong Hoon , Park Cheolmin
Published: March 2009

A new type of nonvolatile ferroelectric poly(vinylidene fluoride‐co‐trifluoroethylene) (P(VDF‐TrFE)) memory based on an organic thin‐film transistor (OTFT) with a single crystal of tri‐isopropylsilylethynyl pentacene (TIPS‐PEN) as the active layer is developed. A bottom‐gate OTFT is fabricated with a thin P(VDF‐TrFE) film gate insulator on which a one‐dimensional ribbon‐type TIPS‐PEN single crystal, grown via a solvent‐exchange method, is positioned between the Au source and drain electrodes. Post‐thermal treatment optimizes the interface between the flat, single‐crystalline ab plane of TIPS‐PEN and the polycrystalline P(VDF‐TrFE) surface with characteristic needle‐like crystalline lamellae. As a consequence, the memory device exhibits a substantially stable source–drain current modulation with an ON/OFF ratio hysteresis greater than 103, which is superior to a ferroelectric P(VDF‐TrFE) OTFT that has a vacuum‐evaporated pentacene layer. Data retention longer than 5 × 104 s is additionally achieved in ambient conditions by incorporating an interlayer between the gate electrode and P(VDF‐TrFE) thin film. The device is environmentally stable for more than 40 days without additional passivation. The deposition of a seed solution of TIPS‐PEN on the chemically micropatterned surface allows fabrication arrays of TIPS‐PEN single crystals that can be potentially useful for integrated arrays of ferroelectric polymeric TFT memory.
Pathogenicity in the tubercle bacillus: molecular and evolutionary determinants
Authors: Gordon Stephen V. , Bottai Daria , Simeone Roxane , Stinear Timothy P. , Brosch Roland
Published: March 2009

In contrast to the great majority of mycobacterial species that are harmless saprophytes, Mycobacterium tuberculosis and other closely related tubercle bacilli have evolved to be among the most important human and animal pathogens. The need to develop new strategies in the fight against tuberculosis (TB) and related diseases has fuelled research into the evolutionary success of the M. tuberculosis complex members. Amongst the various disciplines, genomics and functional genomics have been instrumental in improving our understanding of these organisms. In this review we will present some of the recent key findings on molecular determinants of mycobacterial pathogenicity and attenuation, the evolution of M. tuberculosis, genome dynamics, antigen mining for improved diagnostic and subunit antigens, and finally the identification of novel drug targets. The genomics revolution has changed the landscape of TB research, and now underpins our renewed efforts to defeat this deadly pathogen.
Totally tubular: the mystery behind function and origin of the brain ventricular system
Authors: Lowery Laura Anne , Sive Hazel
Published: March 2009

A unique feature of the vertebrate brain is the ventricular system, a series of connected cavities which are filled with cerebrospinal fluid (CSF) and surrounded by neuroepithelium. While CSF is critical for both adult brain function and embryonic brain development, neither development nor function of the brain ventricular system is fully understood. In this review, we discuss the mystery of why vertebrate brains have ventricles, and whence they originate. The brain ventricular system develops from the lumen of the neural tube, as the neuroepithelium undergoes morphogenesis. The molecular mechanisms underlying this ontogeny are described. We discuss possible functions of both adult and embryonic brain ventricles, as well as major brain defects that are associated with CSF and brain ventricular abnormalities. We conclude that vertebrates have taken advantage of their neural tube to form the essential brain ventricular system.
Improvement of Yersinia frederiksenii phytase performance by a single amino acid substitution
Authors: Fu Dawei , Huang Huoqing , Meng Kun , Wang Yaru , Luo Huiying , Yang Peilong , Yuan Tiezheng , Yao Bin
Published: March 2009

A new phytase (APPA) with optimum pH 2.5—substantially lower than that of most of microbial phytases (pH 4.5–6.0)—was cloned from Yersinia frederiksenii and heterologously expressed in Escherichia coli. Containing the highly conserved motifs typical of histidine acid phosphatases, APPA has the highest identity (84%) to the Yersinia intermedia phytase (optimal pH 4.5), a member of histidine acid phosphatase family. Based on sequence alignment and molecular modeling of APPA and related phytases, APPA has only one divergent residue, Ser51, in close proximity to the catalytic site. To understand the acidic adaptation of APPA, five mutants (S51A, S51T, S51D, S51K, and S51I) were constructed by site‐directed mutagenesis, expressed in E. coli, purified, and characterized. Mutants S51T and S51I exhibited a shift in the optimal pH from 2.5 to 4.5 and 5.0, respectively, confirming the role of Ser51 in defining the optimal pH. Thus, a previously unrecognized factor other than electrostatics—presumably the side‐chain structure near the active site—contributes to the optimal pH for APPA activity. Compared with wild‐type APPA, mutant S51T showed higher specific activity, greater activity over pH 2.0–5.5, and increased thermal and acid stability. These properties make S51T a better candidate than the wild‐type APPA for use in animal feed. Biotechnol. Bioeng. 2009;103: 857–864. © 2009 Wiley Periodicals, Inc.
Optimization of a novel headspace–solid‐phase microextraction–gas chromatographic method by means of a Doehlert uniform shell design for the analysis of trace level ethylene oxide residuals in sterilized medical devices
Authors: DiCicco Michael P. , Lang Bridget , Harper Thomas I.
Published: March 2009

Medical devices sterilized by ethylene oxide (EtO) retain trace quantities of EtO residuals, which may irritate patients' tissue. Reliably quantifying trace level EtO residuals in small medical devices requires an extremely sensitive analytical method. In this research, a Doehlert uniform shell design was utilized in obtaining a response surface to optimize a novel headspace–solid‐phase microextraction–gas chromatographic (HS‐SPME‐GC) method developed for analyzing trace levels of EtO residuals in sterilized medical devices, by evaluating sterilized, polymer‐coated, drug‐eluting cardiovascular stents. The effects of four independent experimental variables (HS‐SPME desorption time, extraction temperature, GC inlet temperature and extraction time) on GC peak area response of EtO were investigated simultaneously and the most influential experimental variables determined were extraction temperature and GC inlet temperature, with the fitted model showing no evidence of lack‐of‐fit. The optimized HS‐SPME‐GC method demonstrated overall good linearity/linear range, accuracy, repeatability, reproducibility, absolute recovery and high sensitivity. This novel method was successfully applied to analysis of trace levels of EtO residuals in sterilized/aerated cardiovascular stents of various lengths and internal diameter, where, upon heating, trace EtO residuals fully volatilized into HS for extraction, thereby nullifying matrix effects. As an alternative, this novel HS‐SPME‐GC method can offer higher sensitivity compared with conventional headspace analyzer‐based sampling. Copyright © 2009 John Wiley & Sons, Ltd.
RESCON: Educational project scheduling software
Authors: Deblaere Filip , Demeulemeester Erik , Herroelen Willy
Published: March 2009

In this article we discuss a freely downloadable educational software tool for illustrating project scheduling and project management concepts. The tool features exact and heuristic scheduling procedures and visualizes project networks, project schedules, resource profiles, activity slacks, and project duration distributions. © 2009 Wiley Periodicals, Inc. Comput Appl Eng Educ 19: 327–336, 2011
Intergenerational continuity in convictions: A five‐generation study
Authors: Bijleveld Catrien C. J. H. , Wijkman Miriam
Published: March 2009

Background Intergenerational continuity in offending has been assessed in several studies. However, this has rarely been studied using more than two prospective generations. Also, within‐gender and cross‐gender effects have rarely been addressed. The evidence for mechanisms that may explain transmission is mixed.

Method Using conviction data on five generations (n = 6322) that span the years 1882–2007, transmission from parent to child was studied, disaggregating for males and females. Parental conviction before the birth of the child was studied separately from parental conviction after the birth of the child. Transmission was studied using odds ratios.

Results Parental convictions increase the risk of offspring convictions, although the risk increase is, at around two on average, not extremely high. Delinquency by the mother was also associated with offspring criminality, although because of low prevalence the odds ratios were more variable. Parental delinquency before birth does not lead to increased risk. For serious delinquency, these findings were stronger.

Conclusions The study suggests that nurture rather than hereditary or labelling mechanisms may play a role in intergenerational continuity. Copyright © 2009 John Wiley & Sons, Ltd.
Pharos neurovascular intracranial stent: Elective use for a symptomatic stenosis refractory to medical therapy
Authors: Mocco J , Darkhabani Ziad , Levy Elad I.
Published: March 2009

The Warfarin‐Aspirin Symptomatic Intracranial Disease study investigators demonstrated that medically managed patients with symptomatic intracranial stenosis experience a 7–11% annual stroke risk. Early treatment efforts utilized balloon‐mounted coronary stents, which provided excellent angiographic results (postprocedure stenoses <10%), versus percutaneous transluminal angioplasty (PTA) alone (40%). However, the rigidity of balloon‐mounted coronary stents provided limited access to the tortuous cerebrovasculature. Self‐expanding stents became available for intracranial stenosis treatment in 2002. With increased flexibility, immediate results were encouraging (approximately 30% residual stenosis). However, midterm results have demonstrated disappointingly high rates of restenosis. To address these issues, the Pharos Neurovascular Stent System (Pharos, Micrus Endovascular, San Jose, CA) was developed. The Pharos is a balloon‐expandable stent mounted on a rapid‐exchange PTA catheter especially designed for intracranial endovascular applications. Utilizing the Pharos, we obtained an outstanding angiographic result (0% residual stenosis), with no associated morbidity. The patient was discharged home on postprocedure day 1 and remained symptom‐free, with no in‐stent stenosis, 3 months later. Our experience with the Pharos supports early literature suggesting that this stent may be a valuable treatment option for patients with medically refractory intracranial stenosis. © 2009 Wiley‐Liss, Inc.
The Ever‐Surprising Chemistry of Boron: Enhanced Acidity of Phosphine⋅Boranes
Authors: Hurtado Marcela , Yánez Manuel , Herrero Rebeca , Guerrero Andrés , Dávalos Juan Z. , Abboud José‐Luis M. , Khater Brahim , Guillemin Jean‐Claude
Published: March 2009

The acidity‐enhancing effectof BH3in gas‐phase phosphine⋅boranes compared to the corresponding free phosphines is enormous, between 13 and 18 orders of magnitude in terms of ionization constants. Thus, the enhancement of the acidity of protic acids by Lewis acids usually observed in solution is also observed in the gas phase. For example, the gas‐phase acidities (GA) of MePH2and MePH2⋅BH3differ by about 118 kJ mol−1(see picture).

magnified image

The gas‐phase acidity of a series of phosphines and their corresponding phosphine⋅borane derivatives was measured by FT‐ICR techniques. BH3attachment leads to a substantial increase of the intrinsic acidity of the system (from 80 to 110 kJ mol−1). This acidity‐enhancing effect of BH3is enormous, between 13 and 18 orders of magnitude in terms of ionization constants. This indicates that the enhancement of the acidity of protic acids by Lewis acids usually observed in solution also occurs in the gas phase. High‐level DFT calculations reveal that this acidity enhancement is essentially due to stronger stabilization of the anion with respect to the neutral species on BH3association, due to a stronger electron donor ability of P in the anion and better dispersion of the negative charge in the system when the BH3group is present. Our study also shows that deprotonation of ClCH2PH2and ClCH2PH2⋅BH3is followed by chloride departure. For the latter compound deprotonation at the BH3group is found to be more favorable than PH2deprotonation, and the subsequent loss of Cl−is kinetically favored with respect to loss of Cl−in a typical SN2 process. Hence, ClCH2PH2⋅BH3is the only phosphine⋅borane adduct included in this study which behaves as a boron acid rather than as a phosphorus acid.
An End‐On Azide‐Bridged Antiferromagnetic Single‐Chain Magnet Involving Spin Canting and Field‐Induced Two‐Step Magnetic Transitions
Authors: Yoon Jung Hee , Ryu Dae Won , Kim Hyoung Chan , Yoon Sung Won , Suh Byoung Jin , Hong Chang Seop
Published: March 2009

Two‐step magnetic transitions: An azide‐bridged 1D MnIII coordination polymer with a unique single end‐on mode was prepared; it displayed atypical antiferromagnetic couplings and field‐induced two‐step magnetic transitions (see figure). The spin‐canted phenomenon in the antiferromagnetic chain complex plays a pivotal role in establishing the slow magnetic relaxation.

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Changes in somatodendritic morphometry of rat oculomotor nucleus motoneurons during postnatal development
Authors: Carrascal Livia , Nieto‐Gonzalez Jose Luis , Torres Blas , Nunez‐Abades Pedro
Published: March 2009

This work investigates the somatodendritic shaping of rat oculomotor nucleus motoneurons (Mns) during postnatal development. The Mns were functionally identified in slice preparation, intracellularly injected with neurobiotin, and three‐dimensionally reconstructed. Most of the Mns (∼85%) were multipolar and the rest (∼15%) bipolar. Forty multipolar Mns were studied and grouped as follows: 1–5, 6–10, 11–15, and 21–30 postnatal days. Two phases were distinguished during postnatal development (P1–P10 and P11–P30). During the first phase, there was a progressive increase in the dendritic complexity; e.g., the number of terminals per neuron increased from 26.3 (P1–P5) to 47.7 (P6–P10) and membrane somatodendritic area from 11,289.9 μm2 (P1–P5) to 19,235.8 μm2 (P6–P10). In addition, a few cases of tracer coupling were observed. During the second phase, dendritic elongation took place; e.g., the maximum dendritic length increased from 486.7 μm (P6–P10) to 729.5 μm in adult Mns, with a simplification of dendritic complexity to values near those for the newborn, and a slow, progressive increase in membrane area from 19,235.8 μm2 (P6–P10) to 24,700.3 μm2 (P21–P30), while the somatic area remained constant. In conclusion, the electrophysiological changes reported in these Mns with maturation (Carrascal et al. [2006] Neuroscience 140:1223–1237) cannot be fully explained by morphometric variations; the dendritic elongation and increase in dendritic area are features shared with other pools of Mns, whereas changes in dendritic complexity depend on each population; the first phase paralleled the establishment of vestibular circuitry and the second paralleled eyelid opening. J. Comp. Neurol. 514:189–202, 2009. © 2009 Wiley‐Liss, Inc.
Developmental origins of mosaic brain evolution: Morphometric analysis of the developing zebra finch brain
Authors: Charvet Christine J. , Striedter Georg F.
Published: March 2009

In adult zebra finches (Taeniopygia guttata), the telencephalon occupies 64% of the entire brain. This fraction is similar to what is seen in parrots, but many other birds possess a significantly smaller telencephalon. The aim of the present study was to determine the developmental time course and cellular basis of telencephalic enlargement in zebra finches, and then to compare these findings with what is known about telencephalic enlargement in other birds. To this end we estimated the volumes of all major brain regions from serial sections in embryonic and post‐hatching zebra finches. We also labeled proliferating cells with antibodies against proliferating cell nuclear antigen and phosphorylated histone H3. An important finding to emerge from this work is that the telencephalon of zebra finches at hatching contains a thick proliferative subventricular zone (SVZ) that extends from the subpallium into the dorsal pallium. The data also show that the onset and offset of telencephalic neurogenesis are both delayed in zebra finches relative to quail (Galliformes). This delay in neurogenesis, in conjunction with the expanded SVZ, probably accounts for most of the telencephalic enlargement in passerines such as the zebra finch. In addition, passerines enlarged their telencephalon by decreasing the proportional size of their midbrain tectum. Because the presumptive tectum is proportionally smaller in zebra finches than quail before neurogenesis begins, this difference in tectum size cannot be due to evolutionary alterations in neurogenesis timing. Collectively these findings indicate that several different developmental mechanisms underlie the evolution of a large telencephalon in passerines. J. Comp. Neurol. 514:203–213, 2009. © 2009 Wiley‐Liss, Inc.
Monocyte‐derived macrophage microparticles impart tissue factor activity to biomaterial surfaces
Authors: Patchipulusu Sirisha , Turturro Michael , Hall Connie L.
Published: March 2009

The initiation of coagulation on biomaterials is attributed to the contact pathway of coagulation. However, recent discoveries of blood‐borne tissue factor (TF) activity suggest that the TF pathway of coagulation may contribute to thrombosis on biomaterials. To evaluate the role of TF bearing microparticles to biomaterial thrombogenicity, the adhesion of monocyte‐derived macrophage microparticles (MMPs) to bare, bovine serum albumin (BSA) blocked, and plasma‐coated materials was examined. MMP suspensions consisted of 20–37% TF positive particles that exhibited TF activity. Data from static experiments with polyethylene (PE), polydimethylsiloxane (PDMS), polystyrene (PS), and glass knitted and woven Dacron® grafts showed that MMPs adhered to uncoated, and plasma coated surfaces supported TF activity, whereas surfaces blocked with BSA supported less activity. Flow studies were performed on plasma‐coated glass and tissue culture‐treated polystyrene (TCPS) as a model system to demonstrate deposition and firm adhesion of microparticles under physiologic flow conditions. MMPs deposited and imparted TF activity to plasma‐coated glass at wall shear rates of 100, 400, and 1200 sec−1. Deposition on TCPS was comparable to glass at 100 sec−1, but virtually nonexistent at the two higher shear rates after a 1 h perfusion, implying material and shear dependent adhesion. The localization of procoagulant MMPs to biomaterial surfaces could lead to an increased risk of thrombosis on cardiovascular implants beyond that anticipated by the contact pathway alone. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010
In vivo and in vitro characterization of poly(styrene‐b‐isobutylene‐b‐styrene) copolymer stent coatings for biostability, vascular compatibility and mechanical integrity
Authors: Strickler Fred , Richard Robert , McFadden Sharon , Lindquist Jeff , Schwarz Marlene C. , Faust Rudolf , Wilson Gregory J. , Boden Mark
Published: March 2009

The TAXUS® Express 2™Paclitaxel Eluting Coronary Stent System employs a coating consisting of the thermoplastic elastomer, poly(styrene‐b‐isobutylene‐b‐styrene; SIBS), selected for its drug‐eluting characteristics, vascular compatibility, mechanical properties, and biostability. This study was conducted to evaluate the impact of different SIBS (17−51 mole % styrene) compositions on mechanical properties, chemical stability, and vascular compatibility. Mechanical property (stress−strain measurements) and stability studies were conducted on polymer films with five different styrene contents (17, 24, 32, 39, and 51 mole %). The ultimate tensile strength did not change significantly with composition, but the elongation at break decreased with increased styrene content. A pulsatile fatigue test further confirmed the mechanical stability of SIBS up to 39 mole % styrene. The vascular compatibility of five different SIBS compositions was assessed using SIBS‐only coated stents, in the coronary and carotid arteries in a porcine model study. The stability of the vessel wall, rate/degree of endothelialization, inflammation, and thrombus at timepoints from 30 to 180 days were evaluated. The results confirm vascular compatibility over the range of 17−51 mole % styrene. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010