bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of virtualization in computing education
Authors: Gaspar Alessio , Langevin Sarah , Armitage William , Sekar R. , Daniels T.
Published: March 2008

Over the past years, many problems related to the system administration of laboratories for undergraduate system-oriented courses have found elegant solutions in the deployment of virtualization suites. This technological advance enabled these courses to switch from a mostly descriptive content to learning activities which engage students in hands-on, authentic, problem-based learning. Since this type of activity requires students to be administrators of their own virtual machines (VM) or even virtual networks, the experience gained is intrinsically authentic. The potential impact on student learning, as compared to simulation or lecture only based setups is worth investigating for laboratories in operating systems, networking, computer security, system administration, etc.

We propose to review the increasingly important role that virtualization is playing in computing education from 2 perspectives;

(1) Classrooms' system administration and technological advances which support the development of new pedagogies

(2) Pedagogical advances which instructors can now implement thanks to these technologies and their impact on students learning from either quantitative or qualitative perspectives

The presenters will share their experience leading the Xen Worlds, V-NetLab and SOFTICE projects.
Poogle and the unknown-answer assignment
Authors: Head Christopher C. D. , Wolfman Steven A.
Published: March 2008

Most CS1 assignments are "known answer" assignments, requiring students to implement already-solved problems with no user but their grader and themselves. In this paper, we present Poogle: a freely available framework for designing unknown-answer assignments. Poogle assignments are open-ended, graphical, and multi-user. Poogle makes it easy for students to share their creations with their users: fellow students and the general public. We present two freely available CS1 assignments based on Poogle and discuss outcomes from use of one of them in a CS1 course.
Ethics training and decision-making
Authors: Spradling Carol , Soh Leen-Kiat , Ansorge Charles
Published: March 2008

A national web-based survey using SurveyMonkey.com was administered to 700 undergraduate computer science programs in the United States as part of a stratified random sample of 797 undergraduate computer science programs. The 251 program responses (36% response rate) regarding social and professional issues (computer ethics) are presented. This article describes the demographics of the respondents, presents results concerning whether programs teach social and professional issues, who teaches, the role of training in these programs, the decision making process as it relates to computer ethics and why some programs are not teaching computer ethics. Additionally, we provide suggestions for computer science programs regarding ethics training and decision-making and we share reasons why schools are not teaching computer ethics.
Using iPodLinux in an introductory OS course
Authors: Lawson Barry , Barnett Lewis
Published: March 2008

This paper describes a proof of concept for introducing iPods and iPodLinux into a one-semester introductory undergraduate operating systems course. iPodLinux is a version of the Linux operating system modified to run on iPods. We added a project to our course in which the students modified the iPodLinux kernel, and we supplemented lectures by discussing specifics of the Linux implementation as they relate to general operating systems concepts. We feel the course was much improved by these additions, with no substantive omission of regular material. Student response was very enthusiastic, and we feel the new material enhanced their course experience by providing a component that was empowering and helped to further improve their knowledge and skills.
Identifying important and difficult concepts in introductory computing courses using a delphi process
Authors: Goldman Ken , Gross Paul , Heeren Cinda , Herman Geoffrey , Kaczmarczyk Lisa , Loui Michael C. , Zilles Craig
Published: March 2008

A Delphi process is a structured multi-step process that uses a group of experts to achieve a consensus opinion. We present the results of three Delphi processes to identify topics that are important and difficult in each of three introductory computing subjects: discrete math, programming fundamentals, and logic design. The topic rankings can be used to guide both the coverage of standardized tests of student learning (i.e., concept inventories) and can be used by instructors to identify what topics merit emphasis.
Bloom's taxonomy revisited
Authors: Starr Christopher W. , Manaris Bill , Stalvey RoxAnn H.
Published: March 2008

Traditionally, Bloom's Taxonomy has been used for creating exams and other student assessment instruments. In this paper, we advocate its use for specifying learning outcomes in computer science prior to assessment. We have found, over a period of three years, that this facilitates programmatic assessment and related accreditation activities; it benefits instructors selecting pedagogical tools and assignments; and it enhances communication among faculty engaged in curricular development. We describe Bloom's Taxonomy, illustrate a simple process for applying it in computer science (and other disciplines), and present a case study of how it may be applied in a CS1 course. We believe this process has considerably strengthened our department's assessment program and its ability to maintain its ABET accreditation.
Evaluating a breadth-first cs 1 for scientists
Authors: Dodds Zachary , Libeskind-Hadas Ran , Alvarado Christine , Kuenning Geoff
Published: March 2008

This paper presents a thorough evaluation of CS for Scientists, a CS 1 course designed to provide future scientists with an overview of the discipline. The course takes a breadth-first approach that leverages its students' interest and experience in science, mathematics, and engineering. In contrast to many other styles of CS 1, this course does not presume that its students will study more computer science, but it does seek to prepare them should they choose to. We summarize the past year's worth of assessments of student learning, retention, and affect -- with particular attention paid to women's voices. Where possible, we contrast these student measures with those from a traditional, imperative-first CS1 that this new course replaced. The data thus far suggest that CS for Scientists significantly improves students' understanding of CS, its applications, and practice.
Scratching the surface of advanced topics in software engineering
Authors: Sivilotti Paolo A. G. , Laugel Stacey A.
Published: March 2008

A common approach for introducing computer science to middle school students is to teach them a simple yet engaging programming language A different approach is to teach them some advanced topic independent of any particular language or syntax We describe a 3-hour workshop module designed to do both This module has been piloted with a group of thirty 8th grade girls. It uses the Scratch programming language to develop the advanced software engineering concepts of specifications, refinement, and composition After this module, students were enthusiastic about continuing to program in Scratch independently and also felt they learned something about computer science as a discipline.
Using cognitive conflict and visualisation to improve mental models held by novice programmers
Authors: Ma Linxiao , Ferguson John D. , Roper Marc , Ross Isla , Wood Murray
Published: March 2008

Recent research has found that many novice programmers often hold non-viable mental models of basic programming concepts such as assignment and object reference, which can limit their potential to develop programming skills. This paper proposes a constructivist-based teaching model that integrates cognitive conflict and program visualisation with the aim of supporting novice programmers in the formulation of appropriate mental models. The results of an initial empirical study produced three findings of note. Firstly, a teaching model based on either visualisation alone or cognitive conflict integrated with visualisation can help students develop viable models of value assignment. Secondly, there was evidence to suggest that cognitive conflict integrated with visualisation outperformed visualisation alone in helping students develop viable models of the more challenging concept of object reference assignment. And thirdly, there was evidence of an improvement in students' understanding of value and object reference assignment using the teaching model based on visualisation and cognitive conflict.
Exploring studio-based instructional models for computing education
Authors: Hundhausen Christopher D. , Narayanan N Hari , Crosby Martha E.
Published: March 2008

While the demand for college graduates with computing skills continues to rise, such skills no longer equate to mere programming skills. Modern day computing jobs demand design, communication, and collaborative work skills as well. Since traditional instructional methods in computing education tend to focus on programming skills, we believe that a fundamental rethinking of computing education is in order. We are exploring a new "studio-based" pedagogy that actively engages undergraduate students in collaborative, design-oriented learning. Adapted from architectural education, the studio-based instructional model emphasizes learning activities in which students (a) construct personalized solutions to assigned computing problems, and (b) present solutions to their instructors and peers for feedback and discussion within the context of "design crits." We describe and motivate the studio-based approach, review previous efforts to apply it to computer science education, and propose an agenda for multi-institutional research into the design and impact of studio-based instructional models. We invite educators to participate in a community of research and practice to advance studio-based learning in computing education.
Student perceptions of computer science
Authors: Biggers Maureen , Brauer Anne , Yilmaz Tuba
Published: March 2008

Students who develop a strong interest in another field can hardly be fair target for retention efforts. There are others, however, who might do very well in this field but who leave computer science because of misunderstandings about and a negative experience in this academic major. Retention literature suggests and provides numerous examples of initiatives that improve student retention. To determine how best to impact student retention in your computer science department, a comprehensive understanding of the student experience of your major is essential. Not only is it important to know why students leave your major, but an understanding of why they stay can be useful in developing high impact initiatives.

The current study involves a comparative examination of students who graduated from the computer science (CS) major at Georgia Institute of Technology in Atlanta, Georgia (Stayers) with students who chose to leave the major (Leavers). Specifically, perceptions and experiences of computer science as a field in general and the climate of the major were studied. Comparative data collected provided insights into reasons why they entered into the major, about belief of adequate preparation and confidence going into the major, definitions of CS and other related factors. Results were analyzed to identify potential target areas and concrete implementation strategies are suggested for improved retention in the computer science major at this institution.
A case study of retention practices at the University of Illinois at Urbana-Champaign
Authors: Crenshaw Tanya L. , Chambers Erin Wolf , Metcalf Heather
Published: March 2008

Computer science is seeing a decline in enrollment at all levels of education. One key strategy for reversing this decline is to improve methods of student retention. This paper, based on a 10-month case study at the Department of Computer Science at the University of Illinois at Urbana-Champaign, examines two aspects of student retention at both the graduate and undergraduate levels: community identity and community relationships. Our data shows that students feel isolated from each other, faculty, and members of the greater computer science community. Given our findings, we highlight existing programs and propose new programs which improve student-community interactions. While the lessons learned might not apply at every institution, they constitute a valuable case study for improving conditions for students at large research universities.
Noteblogging
Authors: Simon Beth , Davis Krista , Griswold William G. , Kelly Michael , Malani Roshni
Published: March 2008

Classroom note taking tends to be a private activity, hiding a wealth of knowledge in both content and method. With the advent of the web, whose technology and culture seemingly invites everyone to share everything, we are prompted to ask how making note taking a public activity -- noteblogging -- might advance learning. What does a blog about a computer science classroom look like? What supports are needed to enable noteblogging as a form of auxiliary instruction? In this paper we overview the design and use of noteblogging as part of the Ubiquitous Presenter digital classroom system. With NoteBlogger, students with Tablet PCs take handwritten notes digitally on top of the instructor's slides, and their notes are instantly reviewable by other students in class using a web browser. We examine the impact of noteblogging on a CS1 course through interviews with bloggers (to reveal their motivation and understand their choice of content) and blog watchers (to learn when and why they watch). We also analyze the blogs in this CS1 course to identify their educational contribution. We find that noteblogging enables a unique classroom participation model that specifically engages more advanced students. Blog content spans many levels of intellectual engagement, which can support a range of learners in CS1 as well as perhaps model for them various levels of reflection.
Operational experience with a virtual networking laboratory
Authors: Wiseman Charlie , Wong Ken , Wolf Tilman , Gorinsky Sergey
Published: March 2008

Virtual laboratories are a potential replacement for standard laboratory facilities. Use of these virtual resources can reduce cost and maintenance overheads for teaching institutions while still ensuring that students have access to real equipment. Previous work indicates that students respond well to such environments, but one important operational aspect has been overlooked. In this work, we consider instructor overhead by comparing the amount of work required to teach courses with and without the use of a virtual laboratory. In particular, we examine two graduate computer networking courses, each taught with the standard software-only approach and then taught later with the Open Network Laboratory. Our data show that the effort required by the instructor to use a virtual laboratory is not much more than in a software-only environment, and that the increased interaction between student and instructor can be beneficial as the student questions are primarily focused on fundamental networking concepts.
Local
Authors: Barbosa Jorge , Hahn Rodrigo , Rabello Solon , Barbosa Débora
Published: March 2008

The increasing use of mobile devices and the dissemination of wireless networks have stimulated mobile and ubiquitous computing research. In this context, education is being considered one of the main application areas. New pedagogical opportunities are created through the use of location systems to track learners, and through context awareness support. This paper proposes a model to explore these opportunities using location information and context management as learning support tools. This model, called LOCAL, was conceived for small scale learning environments, but can be applied in large-scale as well. The model was implemented and the initial results show its utility to assist the teaching and learning processes.
Inspiring blind high school students to pursue computer science with instant messaging chatbots
Authors: Bigham Jeffrey P. , Aller Maxwell B. , Brudvik Jeremy T. , Leung Jessica O. , Yazzolino Lindsay A. , Ladner Richard E.
Published: March 2008

Blind students are an underrepresented group in computer science. In this paper, we describe our experience preparing and leading the computer science track at the National Federation of the Blind Youth Slam. As part of this workshop, fifteen blind high school students created and personalized instant messaging chatbots, a project designed to be completely accessible to blind students. Chatbots enable students to infuse their own personalities into a socially-oriented program that incorporates ideas from artificial intelligence, natural language processing, and web services. We first outline the chatbots project and curriculum, which has wide appeal for all students, and then offer general design principles used to create it that can help ensure the accessibility of future projects. Students created their chatbots using a real programming language and were guided by both blind and sighted mentors. By programming from the start in a supportive environment, our students will gain the confidence to persevere in computer science in the future.
Course experiences of computing students with disabilities
Authors: Deibel Katherine
Published: March 2008

Inclusive education is the practice of making sure that all students of all abilities have positive learning experiences. The study presented in this paper explores the current state of inclusive practices in computing education by presenting four case studies of students with disabilities taking their first computing courses. Their experiences share many common themes that reveal insights into their college experiences and connect with current theories as to how to achieve inclusive education. New technologies, such as podcasting, for promoting inclusion are also suggested.
Undergraduate research experiences in data mining
Authors: Rahal Imad
Published: March 2008

The new interdisciplinary field of Data Mining emerged in the early 1990s as a response to the profusion of digital data generated in numerous fields such as biology, chemistry, astronomy, advertising, banking and finance, retail market, stock market, and the WWW. In this paper, I describe an undergraduate course in Data Mining offered at the College of Saint Benedict and Saint John's University in Spring of 2007 as a CSCI-317-upper-division "Topics in Computer Science"- course, entitled "Data Intelligence." One of the main objectives of the course was to engage students in experimental computing research through a number of carefully planned research activities resulting in better understanding of the course contents and deeper insights into the challenges faced by the data mining community.
A query simulation system to illustrate database query execution
Authors: Allenstein Brett , Yost Andrew , Wagner Paul , Morrison Joline
Published: March 2008

The underlying processes that enable database query execution are fundamental to understanding database management systems. However, these processes are complex and can be difficult to explain and illustrate. To address this problem, we have developed a Java-based query simulation system that enables students to visualize the steps involved in processing DML queries. We performed a field experiment to evaluate the system, and the results suggest that the system improves student comprehension of the query execution process.
Introducing an experimental cognitive robotics curriculum at historically black colleges and universities
Authors: Williams Andrew B. , Touretzky David S. , Tira-Thompson Ethan J. , Manning LaVonne , Boonthum Chutima , Allen Clement S.
Published: March 2008

A successful collaboration between Spelman College and Carnegie Mellon University led to an NSF-funded Broadening Participation in Computing project to set up robotics education laboratories and introduce undergraduate instruction in cognitive robotics at three other Historically Black Colleges and Universities (HBCUs). We give a brief overview of cognitive robotics and the Tekkotsu software architecture, and describe our experiences teaching computer science students with no previous robotics exposure to program sophisticated mobile robots.
A bioinformatics track in computer science
Authors: Khuri Sami
Published: March 2008

In this paper, we describe the bioinformatics track we created to better prepare students for health, medical and life science professions. Our program was motivated by the fact that bioinformatics training is in high demand. Many universities have responded to this demand by creating majors in bioinformatics, while others by creating minors in bioinformatics. Our response was less extreme as we opted for a computer science track in bioinformatics which we describe in this article.
Grace hopper visits the neighborhood
Authors: Townsend Gloria Childress , Barker Lecia , Menzel Suzanne , Cohoon J. McGrath
Published: March 2008

This paper highlights several viewpoints concerning a small regional conference for women in computing, which is modeled after the successful and well-known Grace Hopper Celebration of Women in Computing. The viewpoints include rationale for the conference, descriptions of the celebration that provide a snapshot which captures the ease of organizing a similar event at other regional sites, additional sources for finding complete information (including a detailed how-to manual) and an account of the assessment of two recent regional celebrations performed by senior researchers at the National Center of Women and Information Technology (NCWIT).
Improving the persistence of first-year undergraduate women in computer science
Authors: Powell Rita Manco
Published: March 2008

This paper describes a study of undergraduate women's retention in the first-year of the computer science major at the University of Pennsylvania for the purpose of identifying the underlying issues responsible for attrition. The subsequent steps taken by the faculty to improve women's retention is also discussed.
The effect of using problem-solving software tutors on the self-confidence of female students
Authors: Kumar Amruth N.
Published: March 2008

We examined whether using problem-solving software tutors in
Computer Science I
can help improve the self-confidence of female students. We analyzed the data collected by five software tutors in spring 2006. We found that 1) the self-confidence of female
Computer Science I
students before using the software tutors was in many cases lower than that of male students, as has been stated in prior literature; 2) Using problem-solving software tutors improved the self-confidence of female students to be on par with that of male students when female students started with lower prior self-confidence. Since researchers have suggested that self-confidence is one of the factors contributing to the shrinking pipeline, problem-solving software tutors can be used to improve the retention of female students in Computer Science.
It seemed like a good idea at the time
Authors: Boustedt Jonas , McCartney Robert , Tenenberg Josh , Anderson Scott D. , Eastman Caroline M. , Garcia Daniel D. , Gestwicki Paul V. , Menzin Margaret S.
Published: March 2008

We often learn of successful pedagogical experiments, but we seldom hear of the the ones that failed. For this special session we solicited submissions from the SIGCSE membership, selected the best from among these, and will have presentations at the session by the selected authors. Our contributions describe pedagogical approaches that seemed to be good ideas but turned out as failures. Contributors will describe their pedagogical experiment, the rationale for the experiment, evidence of failure, and lessons learned.
Teaching software development with ATDD and easyaccept
Authors: Sauvé Jacques Philippe , Abath Neto Osório Lopes
Published: March 2008

In this paper, we report our experience in teaching software development to Computer Science undergraduate students using acceptance test-driven development (ATDD) and the acceptance testing tool EasyAccept. A typical software design course in a Computer Science curriculum has been modified to include project assignments with executable analysis, which gives students more focus on meeting requirements, boosts confidence in the code being written and results in increased software correctness. We evaluate the benefits of the approach and give suggestions on how to cope with its limitations.
Computer science
Authors: Lazowska Ed
Published: March 2008

Computing research has made remarkable advances, but there's much more to be accomplished. The next few decades of advances should be even more significant, and even more interesting, than the past few.

The National Science Foundation has created the Computing Community Consortium to engage computing researchers in an ongoing process of visioning - of imagining what we might contribute to the world, in terms that we and the world might both appreciate.

This process is just beginning, and I'd like to take this opportunity to engage you. I will review the progress that our field has made, and I'll present a number of "grand challenge" problems that we should be prepared to tackle in the coming decade. I'll invite your contributions.
Alcohol and lipid metabolism
Authors: Sozio Margaret , Crabb David W.
Published: March 2008

Many new mechanisms for alcoholic steatosis have been suggested by work reported in the last five years. These include alterations of transcriptional controls of lipid metabolism, better understanding of the effects of abnormal methionine metabolism on the endoplasmic reticulum stress response, unraveling of the basis for sensitization of the Kupffer cell to lipopolysaccharide, a better understanding of the role of cytokines and adipokines in alcoholic liver disease, and implication of the innate immune and complement systems in responses to alcohol. Much of this work has been facilitated by work with knockout mice. Undoubtedly, there are interrelationships among these various pathogenic mechanisms that ultimately will provide a more cohesive picture of how heavy alcohol use deranges hepatic lipid metabolism.
Partial leptin deficiency favors diet-induced obesity and related metabolic disorders in mice
Authors: Begriche Karima , Lettéron Philippe , Abbey-Toby Adjé , Vadrot Nathalie , Robin Marie-Anne , Bado André , Pessayre Dominique , Fromenty Bernard
Published: March 2008

Partial leptin deficiency is not uncommon in the general population. We hypothesized that leptin insufficiency could favor obesity, nonalcoholic steatohepatitis (NASH), and other metabolic abnormalities, particularly under high calorie intake. Thus, mice partially deficient in leptin ( ob/+) and their wild-type (+/+) littermates were fed for 4 mo with a standard-calorie (SC) or a high-calorie (HC) diet. Some ob/+ mice fed the HC diet were also treated weekly with leptin. Our results showed that, when fed the SC diet, ob/+ mice did not present significant metabolic abnormalities except for elevated levels of plasma adiponectin. Under high-fat feeding, increased body fat mass, hepatic steatosis, higher plasma total cholesterol, and glucose intolerance were observed in +/+ mice, and these abnormalities were further enhanced in ob/+ mice. Furthermore, some metabolic disturbances, such as blunted plasma levels of leptin and adiponectin, reduced UCP1 expression in brown adipose tissue, increased plasma liver enzymes, β-hydroxybutyrate and triglycerides, and slight insulin resistance, were observed only in ob/+ mice fed the HC diet. Whereas de novo fatty acid synthesis in liver was decreased in +/+ mice fed the HC diet, it was disinhibited in ob/+ mice along with the restoration of the expression of several lipogenic genes. Enhanced expression of several genes involved in fatty acid oxidation was also observed only in ob/+ animals. Leptin supplementation alleviated most of the metabolic abnormalities observed in ob/+ fed the HC diet. Hence, leptin insufficiency could increase the risk of obesity, NASH, glucose intolerance, and hyperlipidemia in a context of calorie overconsumption.
Testosterone and DHEA activate the glucose metabolism-related signaling pathway in skeletal muscle
Authors: Sato Koji , Iemitsu Motoyuki , Aizawa Katsuji , Ajisaka Ryuichi
Published: March 2008

Circulating dehydroepiandrosterone (DHEA) is converted to testosterone or estrogen in the target tissues. Recently, we demonstrated that skeletal muscles are capable of locally synthesizing circulating DHEA to testosterone and estrogen. Furthermore, testosterone is converted to 5α-dihydrotestosterone (DHT) by 5α-reductase and exerts biophysiological actions through binding to androgen receptors. However, it remains unclear whether skeletal muscle can synthesize DHT from testosterone and/or DHEA and whether these hormones affect glucose metabolism-related signaling pathway in skeletal muscles. We hypothesized that locally synthesized DHT from testosterone and/or DHEA activates glucose transporter-4 (GLUT-4)-regulating pathway in skeletal muscles. The aim of the present study was to clarify whether DHT is synthesized from testosterone and/or DHEA in cultured skeletal muscle cells and whether these hormones affect the GLUT-4-related signaling pathway in skeletal muscles. In the present study, the expression of 5α-reductase mRNA was detected in rat cultured skeletal muscle cells, and the addition of testosterone or DHEA increased intramuscular DHT concentrations. Addition of testosterone or DHEA increased GLUT-4 protein expression and its translocation. Furthermore, Akt and protein kinase C-ζ/λ (PKC-ζ/λ) phosphorylations, which are critical in GLUT-4-regulated signaling pathways, were enhanced by testosterone or DHEA addition. Testosterone- and DHEA-induced increases in both GLUT-4 expression and Akt and PKC-ζ/λ phosphorylations were blocked by a DHT inhibitor. Finally, the activities of phosphofructokinase and hexokinase, main glycolytic enzymes, were enhanced by testosterone or DHEA addition. These findings suggest that skeletal muscle is capable of synthesizing DHT from testosterone, and that DHT activates the glucose metabolism-related signaling pathway in skeletal muscle cells.
Spermidine/spermine-N1-acetyltransferase: a key metabolic regulator
Authors: Pegg Anthony E.
Published: March 2008

Spermidine/spermine- N1-acetyltransferase (SSAT) regulates cellular polyamine content. Its acetylated products are either excreted from the cell or oxidized by acetylpolyamine oxidase. Since polyamines play critical roles in normal and neoplastic growth and in ion channel regulation, SSAT is a key enzyme in these processes. SSAT is very highly regulated. Its content is adjusted in response to alterations in polyamine content to maintain polyamine homeostasis. Certain polyamine analogs can mimic the induction of SSAT and cause a loss of normal polyamines. This may have utility in cancer chemotherapy. SSAT activity is also induced via a variety of other stimuli, including toxins, hormones, cytokines, nonsteroidal anti-inflammatory agents, natural products, and stress pathways, and by ischemia-reperfusion injury. These increases are initiated by alterations in Sat1 gene transcription reinforced by alterations at the other regulatory steps, including protein turnover, mRNA processing, and translation. Transgenic manipulation of SSAT activity has revealed that SSAT activity links polyamine metabolism to lipid and carbohydrate metabolism by means of alterations in the content of acetyl-CoA and ATP. A high level of SSAT stimulates flux through the polyamine biosynthetic pathway, since biosynthetic enzymes are induced in response to the fall in polyamines. This sets up a futile cycle in which ATP is used to generate S-adenosylmethionine for polyamine biosynthesis and acetyl-CoA is consumed in the acetylation reaction. A variety of other effects of increased SSAT activity include death of pancreatic cells, blockage of regenerative tissue growth, behavioral changes, keratosis follicularis spinulosa decalvans, and hair loss. These are very likely due to changes in polyamine and putrescine levels, although increased oxidative stress via the oxidation of acetylated polyamines may also contribute. Recently, it was found that the SSAT protein and/or a related protein, thialysine acetyltransferase, interacts with a number of other important proteins, including the hypoxia-inducible factor-1 α-subunit, the p65 subunit of NF-κB, and α9β1-integrin, altering the function of these proteins. It is not yet clear whether this functional alteration involves protein acetylation, local polyamine concentration changes, or other effects. It has been suggested that SSAT may also be a useful target in diseases other than cancer, but the wide-ranging physiological and pathophysiological effects of altered SSAT expression will require very careful limitation of such strategies to the relevant cells to avoid toxic effects.
Calcitriol blunts the deleterious impact of advanced glycation end products on endothelial cells
Authors: Talmor Yeela , Golan Eliezer , Benchetrit Sydney , Bernheim Jacques , Klein Osnat , Green Janice , Rashid Gloria
Published: March 2008

Advanced glycation end products (AGEs), which are elevated in diabetic and uremic patients, may induce vascular dysfunctions, and calcitriol may improve the cardiovascular complications. Therefore, we examined whether calcitriol may modify the endothelial response to AGEs stimulation. Knowing the importance of nuclear factor-κB in endothelial inflammatory responses, the effect of AGEs and calcitriol on this pathway was also studied. Calcitriol was added to endothelial cells previously incubated with AGE-human serum albumin (HSA). AGE-HSA induced a decrease in endothelial nitric oxide synthase (eNOS) mRNA expression and enzyme activity. Addition of calcitriol to AGE-HSA-treated endothelial cells improved the decreased action of AGEs on the eNOS system. AGE-HSA increased the AGEs receptor mRNA and protein, which were both blunted by calcitriol. The parallel elevation of interleukin-6 mRNA in the presence of AGE-HSA was also blunted by calcitriol. The NF-κB-p65 DNA binding activity was enhanced and associated with a decrease in inhibitor κBα (IκBα) and an increase in phosphorylated (p)-IκBα levels. Addition of calcitriol blunted the AGEs-induced elevation of NF-κB-p65 DNA binding activity, a phenomenon related to an increased expression of IκBα. This increase was correlated to declined p-IκBα levels. The present results support the concept that calcitriol may act as a vascular protective agent counteracting the probable deleterious actions of AGEs on endothelial cell activities.
Genetic variant in the glucose transporter type 2 is associated with higher intakes of sugars in two distinct populations
Authors: Eny Karen M. , Wolever Thomas M. S. , Fontaine-Bisson Bénédicte , El-Sohemy Ahmed
Published: March 2008

Glucose sensing in the brain has been proposed to be involved in regulating food intake, but the mechanism is not known. Glucose transporter type 2 (GLUT2)-null mice fail to control their food intake in response to glucose, suggesting a potential role for this transporter as a glucose sensor in the brain. Here we show that individuals with a genetic variation in GLUT2 (Thr110Ile) have a higher daily intake of sugars in two distinct populations. In the first population, compared with individuals with the Thr/Thr genotype, carriers of the Ile allele had a significantly higher intake of sugars as assessed from 3-day food records administered on two separate visits ( visit 1: 112 ± 9 vs. 86 ± 4 g/day, P = 0.01; visit 2: 111 ± 8 vs. 82 ± 4 g/day, P = 0.003), demonstrating within-population reproducibility. In a second population, carriers of the Ile allele also reported consuming a significantly greater intake of sugars (131 ± 5 vs. 115 ± 3 g/day, P = 0.007) over a 1-mo period as measured from a food frequency questionnaire. GLUT2 genotypes were not associated with fat, protein, or alcohol intake in either population. These observations were consistent across older and younger adults as well as among subjects with early Type 2 diabetes and healthy individuals. Taken together, our findings show that a genetic variation in GLUT2 is associated with habitual consumption of sugars, suggesting an underlying glucose-sensing mechanism that regulates food intake.
Human phenylethanolamineN-methyltransferase genetic polymorphisms and exercise-induced epinephrine release
Authors: Ji Yuan , Snyder Eric M. , Fridley Brooke L. , Salavaggione Oreste E. , Moon Irene , Batzler Anthony , Yee Vivien C. , Schaid Daniel J. , Joyner Michael J. , Johnson Bruce D. , Weinshilboum Richard M.
Published: March 2008

Phenylethanolamine N-methyltransferase (PNMT) catalyzes the synthesis of epinephrine from norepinephrine. We previously identified and functionally characterized common sequence variation in the PNMT gene. In the present study, we set out to determine whether common PNMT genetic polymorphisms might be associated with individual variation in circulating epinephrine levels during exercise in 74 Caucasian American subjects. Circulating epinephrine levels were measured in each subject at baseline and during two different levels of exercise, ∼40% and ∼75% of peak workload. The PNMT gene was resequenced with DNA from each study subject. Eight novel PNMT polymorphisms were identified, including a C319T (Arg107Cys) nonsynonymous single nucleotide polymorphism (SNP) and I1G(280)A, a SNP located in the first intron of the gene. The I1G(280)A SNP was significantly associated with decreased exercise-induced circulating epinephrine levels and with a decreased epinephrine-to-norepinephrine ratio. The Cys107 recombinant allozyme displayed significantly lower levels of both PNMT activity and immunoreactive protein than the wild-type allozyme after transfection into COS-1 cells, but it did not appear to be associated with level of epinephrine in these subjects. Electrophoretic mobility shift and reporter gene assays performed with the I1G(280)A SNP indicated that this polymorphism could bind nuclear proteins and might modulate gene transcription. Our studies suggest that functionally significant variant sequence in the human PNMT gene might contribute to individual variation in levels of circulating epinephrine during exercise.
Asymptotic Periodicity of a Higher-Order Difference Equation
Authors: Stevic Stevo
Published: March 2008

We give a complete picture regarding the asymptotic periodicity of positive solutions of the following difference equation:xn=f(xn−p1,…,xn−pk,xn−q1,…,xn−qm),n∈ℕ0, wherepi, i∈{1,…,k}, andqj, j∈{1,…,m}, are natural numbers such thatp1<p2<⋯<pk,q1<q2<⋯0, is increasing in the firstkarguments and decreasing in othermarguments, there is a decreasing functiong∈C[(α,∞),(α,∞)]such thatg(g(x))=x, x∈(α,∞),x=f(x,…,x︸k,g(x),…,g(x)︸m),x∈(α,∞),limx→α+g(x)=+∞, andlimx→+∞g(x)=α. It is proved that if allpi, i∈{1,…,k}, are even and allqj, j∈{1,…,m}are odd, every positive solution of the equation converges to (not necessarily prime) a periodic solution of period two, otherwise, every positive solution of the equation converges to a unique positive equilibrium.
Antithrombotic and Antiatherosclerotic Properties of Olive Oil and Olive Pomace Polar Extracts in Rabbits
Authors: Tsantila Nektaria , Karantonis Haralabos C. , Perrea Despina N. , Theocharis Stamatios E. , Iliopoulos Dimitrios G. , Antonopoulou Smaragdi , Demopoulos Constantinos A.
Published: March 2008

Olive oil polar lipid (OOPL) extract has been reported to inhibit atherosclerosis development on rabbits. Olive pomace polar lipid (PPL) extract inhibits PAF activity in vitro and the most potent antagonist has been identified as a glycerylether-sn-2-acetyl glycolipid with common structural characteristics with the respective potent antagonist of OOPL. The aim of this study was to investigate the effect of PPL on early atherosclerosis development on rabbits and to compare it with the antiatherosclerotic effect of OOPL. OOPL and PPL inhibition potency, towards both PAF action and PAF binding, was tested in vitro on washed rabbit platelets. Consequently, rabbits were divided into three groups (A, B, and C). All groups were fed atherogenic diet for 22 days. Atherogenic diets in groups B and C were enriched with OOPL and PPL, respectively. At the end of the experimental time, rabbits were euthanized and aortic samples were examined histopathologically. OOPL and PPL inhibited PAF-induced aggregation, as well as specific PAF binding, with PPL being more potent. Free and bound PAF levels and PAF-AH activity were significantly elevated at the end of the experimental time. Plasma total cholesterol, HDL cholesterol, LDL cholesterol, and triglycerides levels were also found increased. Groups B and C exhibited significantly increased values of EC50compared to group A. Histopathological examination revealed that the development of early atherosclerosis lesions in groups B and C were significantly inhibited compared to group A. Significant differences were noted in the early atherosclerosis lesions between groups B and C, thus indicating that PPL exhibit its anti-atherosclerotic activity by blocking PAF receptor. Specific PAF antagonists with similar in vitro and in vivo bioactivity to those that have been previously reported in OOPL exist in PPL.
Phthalate-Induced Liver Protection against Deleterious Effects of the Th1 Response: A Potentially Serious Health Hazard
Authors: Badr Mostafa Z. , Shnyra Alexander , Zoubine Mikhail , Norkin Maxim , Herndon Betty , Quinn Tim , Miranda Roberto N. , Cunningham Michael L. , Molteni Agostino
Published: March 2008

Infection withMycobacterium tuberculosis(TB) induces pulmonary immunopathology mediated by classical Th1 type of acquired immunity with hepatic involvement in up to 80% of disseminated cases. Since PPAR agonists cause immune responses characterized by a decrease in the secretion of Th1 cytokines, we investigated the impact of activating these receptors on hepatic pathology associated with a well-characterized model of Th1-type pulmonary response. Male Fischer 344 rats were either maintained on a drug-free diet (groups I and II), or a diet containing diethylhexylphthalate (DEHP), a compound transformed in vivo to metabolites known to activate PPARs, for 21 days (groups III and IV). Subsequently, animals were primed withMycobacterium bovispurified protein derivative (PPD) in a Complete Freund's Adjuvant. Fifteen days later, animals in groups II and IV were challenged with Sepharose 4B beads covalently coupled with PPD, while animals in groups I and III received blank Sepharose beads. Animals with Th1 response (group II) showed a marked structural disruption in the hepatic lobule. Remarkably, these alterations were conspicuously absent in animals which received DEHP (group IV), despite noticeable accumulation of T cells in the periportal triads. Immunostaining and confocal microscopy revealed hepatic accumulation of IFNγ+Th1 and IL-4+Th2 cells in animals from groups II and IV, respectively. Our data suggest a PPARα-mediated suppression of the development of a Th1 immune response in the liver, resulting in hepatoprotective effect. However, potentially negative consequences of PPAR activation, such as decreased ability of the immune system to fight infection and interference with the efficacy of vaccines designed to evoke Th1 immune responses, remain to be investigated.
On the First Curve in the FučiK Spectrum with Weights for a Mixedp-Laplacian
Authors: Leadi Liamidi , Marcos Aboubacar
Published: March 2008

We show the existence of a first curve in the Fučik spectrum with weights for thep-Laplacian under mixed boundary conditions. We also study the asymptotic behavior of this first curve.
Comparative Study of Some New Hybrid Fuzzy Algorithms for Manipulator Control
Authors: Mohan Sudeept , Bhanot Surekha
Published: March 2008

The robot manipulator is a highly complex system, which is multi-input, multi-output, nonlinear, and time variant. Controlling such a system is a tedious and challenging task. In this paper, some new hybrid fuzzy control algorithms have been proposed for manipulator control. These hybrid fuzzy controllers consist of two parts: a fuzzy controller and a conventional or adaptive controller. The outputs of these controllers are superimposed to produce the final actuation signal based on current position and velocity errors. Simulation is used to test these controllers for different trajectories and for varying manipulator parameters. Various performance indices like the RMS error, steady state error, and maximum error are used for comparison. It is observed that the hybrid controllers perform better than only fuzzy or only conventional/adaptive controllers.
On a Discrete Epidemic Model
Authors: Stevic Stevo
Published: March 2008

We investigate the global asymptotic behavior of solutions of the difference equationxn+1=(1−∑j=0k−1xn−j)(1−e−Axn),n∈ℕ0, whereA∈(0,∞),k∈{2,3,…}, and the initial valuesx−k+1,x−k+2,…,x0are arbitrary negative numbers. Asymptotics of some positive solutions of the equation are also found.
Effect of Etching Parameter on Pore Size and Porosity of Electrochemically Formed Nanoporous Silicon
Authors: Kumar Pushpendra , Huber Patrick
Published: March 2008

The most common fabrication technique of porous silicon (PS) is electrochemical etching of a crystalline silicon wafer in a hydrofluoric (HF) acid-based solution. The electrochemical process allows for precise control of the properties of PS such as thickness of the porous layer, porosity, and average pore diameter. The control of these properties of PS was shown to depend on the HF concentration in the used electrolyte, the applied current density, and the thickness of PS. The change in pore diameter, porosity, and specific surface area of PS was investigated by measuring nitrogen sorption isotherms.
On the Study of Chemostat Model with Pulsed Input in a Polluted Environment
Authors: Zhao Zhong , Song Xinyu
Published: March 2008

Chemostat model with pulsed input in a polluted environment is considered. By using the Floquet theorem, we find that the microorganism eradication periodic solution is globally asymptotically stable if the impulsive periodTis more than a critical value. At the same time, we can find that the nutrient and microorganism are permanent if the impulsive periodTis less than the critical value.
Targeted Gene Disruption of the Cyclo (L-Phe, L-Pro) Biosynthetic Pathway inStreptomycessp. US24 Strain
Authors: Sioud Samiha , Karray-Rebai Ines , Aouissaoui Hedi , Aigle Bertrand , Bejar Samir , Mellouli Lotfi
Published: March 2008

We have previously isolated a new actinomycete strain from Tunisian soil calledStreptomycessp. US24, and have shown that it produces two bioactive molecules including a Cyclo (L-Phe, L-Pro) diketopiperazine (DKP). To identify the structural genes responsible for the synthesis of this DKP derivative, a PCR amplification (696 bp) was carried out using theStreptomycessp. US24 genomic DNA as template and two degenerate oligonucleotides designed by analogy with genes encoding peptide synthetases (NRPS). The detection of DKP derivative biosynthetic pathway of theStreptomycessp. US24 strain was then achieved by gene disruption via homologous recombination using a suicide vector derived from the conjugative plasmid pSET152 and containing the PCR product. Chromatography analysis, biological tests and spectroscopic studies of supernatant cultures of the wild-typeStreptomycessp. US24 strain and three mutants obtained by this gene targeting disruption approach showed that the amplified DNA fragment is required for Cyclo (L-Phe, L-Pro) biosynthesis inStreptomycessp. US24 strain. This DKP derivative seems to be produced either directly via a nonribosomal pathway or as a side product in the course of nonribosomal synthesis of a longer peptide.