bluuebunny/crossref_metadata_2025 huggingface dataset:
Technology supports for distributed and collaborative learning over the internet
Authors: Li Qing , Lau Rynson W. H. , Shih Timothy K. , Li Frederick W. B.
Published: February 2008

With the advent of Internet and World Wide Web (WWW) technologies, distance education (e-learning or Web-based learning) has enabled a new era of education. There are a number of issues that have significant impact on distance education, including those from educational, sociological, and psychological perspectives. Rather than attempting to cover exhaustively all the related perspectives, in this survey article, we focus on the technological issues. A number of technology issues are discussed, including distributed learning, collaborative learning, distributed content management, mobile and situated learning, and multimodal interaction and augmented devices for e-learning. Although we have tried to include the state-of-the-art technologies and systems here, it is anticipated that many new ones will emerge in the near future. As such, we point out several emerging issues and technologies that we believe are promising, for the purpose of highlighting important directions for future research.
Partial query resolution for animation authoring
Authors: Kotharu Phani S. , Prabhakaran B.
Published: February 2008

Animations are a part of multimedia and techniques such as motion mapping and inverse kinematics aid in reusing models and motion sequences to create new animations. This reuse approach is facilitated by the use of content-based retrieval techniques that often require fuzzy query resolution. Most fuzzy query resolution approaches work on all the attributes of the query to minimize the database access cost thus resulting in an unsatisfactory result set. It turns out that the query resolution can be carried out in a partial manner to achieve user satisfactory results and aid in easy authoring. In this article, we present two partial fuzzy query resolution approaches, one that results in high-quality animations and the other that produces results with decreasing number of satisfied conditions in the query.
A revenue-rewarding scheme of providing incentive for cooperative proxy caching for media streaming systems
Authors: Ip Alan T. S. , Lui John C. S. , Liu Jiangchuan
Published: February 2008

Network entities cooperating together can improve system performance of media streaming. In this paper, we address the “
incentive issue
” of a cooperative proxy caching system and how to motivate each proxy to provide cache space to the system. To encourage proxies to participate, we propose a “
revenue-rewarding scheme
” to credit the cooperative proxies according to the resources they contribute. A
game-theoretic model
is used to analyze the interactions among proxies under the revenue-rewarding scheme. We propose two cooperative game settings that lead to optimal situations. In particular, (1) We propose a distributed incentive framework for peers to participate in resource contribution for media streaming; (2) Proxies are encouraged to cooperate under the revenue-rewarding scheme; (3) Profit and social welfare are maximized in these cooperative games; and (4) Cost-effective resource allocation is achieved in these cooperative games. Large scale simulation is carried out to validate and verify the merits of our proposed incentive schemes.
An automated end-to-end lecture capture and broadcasting system
Authors: Zhang Cha , Rui Yong , Crawford Jim , He Li-Wei
Published: February 2008

Remote viewing of lectures presented to a live audience is becoming increasingly popular. At the same time, the lectures can be recorded for subsequent on-demand viewing over the Internet. Providing such services, however, is often prohibitive due to the labor-intensive cost of capturing and pre/post-processing. This article presents a complete automated end-to-end system that supports capturing, broadcasting, viewing, archiving and searching of presentations. Specifically, we describe a system architecture that minimizes the pre- and post-production time, and a fully automated lecture capture system called
iCam2
that synchronously captures all contents of the lecture, including audio, video, and presentation material. No staff is needed during lecture capture and broadcasting, so the operational cost of the system is negligible. The system has been used on a daily basis for more than 4 years, during which 522 lectures have been captured. These lectures have been viewed over 20,000 times.
Urban sensing
Authors: Cuff Dana , Hansen Mark , Kang Jerry
Published: February 2008

Embedded networked sensing, having successfully shifted from the lab to the environment, is primed for a more contentious move to the city to where citizens will likely be the target of data collection. This transition will warrant careful study and touch on issues that go far beyond the scientific realm.
Towards 3-query locally decodable codes of subexponential length
Authors: Yekhanin Sergey
Published: February 2008

A
q
-query Locally Decodable Code (LDC) encodes an
n
-bit message
x
as an
N
-bit codeword
C
(
x
), such that one can probabilistically recover any bit

x
i

of the message by querying only
q
bits of the codeword
C
(
x
), even after some constant fraction of codeword bits has been corrupted.

We give new constructions of three query LDCs of vastly shorter length than that of previous constructions. Specifically, given any Mersenne prime
p
= 2

t

− 1, we design three query LDCs of length
N
= exp(
O
(
n

1/
t

)), for every
n
. Based on the largest known Mersenne prime, this translates to a length of less than exp(
O
(
n

10
− 7

)) compared to exp(
O
(
n
1/2
)) in the previous constructions. It has often been conjectured that there are infinitely many Mersenne primes. Under this conjecture, our constructions yield three query locally decodable codes of length
N
= exp(
n

O
(1/log log
n
)

) for infinitely many
n
.

We also obtain analogous improvements for Private Information Retrieval (PIR) schemes. We give 3-server PIR schemes with communication complexity of
O
(
n

10
− 7

) to access an
n
-bit database, compared to the previous best scheme with complexity
O
(
n
1/5.25
). Assuming again that there are infinitely many Mersenne primes, we get 3-server PIR schemes of communication complexity
n

O
(1/log log
n
)

) for infinitely many
n
.

Previous families of LDCs and PIR schemes were based on the properties of low-degree multivariate polynomials over finite fields. Our constructions are completely different and are obtained by constructing a large number of vectors in a small dimensional vector space whose inner products are restricted to lie in an algebraically nice set.
On the minimization of XPath queries
Authors: Flesca S. , Furfaro F. , Masciari E.
Published: February 2008

XPath expressions define navigational queries on XML data and are issued on XML documents to select sets of element nodes. Due to the wide use of XPath, which is embedded into several languages for querying and manipulating XML data, the problem of efficiently answering XPath queries has received increasing attention from the research community. As the efficiency of computing the answer of an XPath query depends on its size, replacing XPath expressions with equivalent ones having the smallest size is a crucial issue in this direction. This article investigates the minimization problem for a wide fragment of XPath (namely
X P
[✶]
), where the use of the most common operators (child, descendant, wildcard and branching) is allowed with some syntactic restrictions. The examined fragment consists of expressions which have not been specifically studied in the relational setting before: neither are they mere conjunctive queries (as the combination of “//” and “*” enables an implicit form of disjunction to be expressed) nor do they coincide with disjunctive ones (as the latter are more expressive). Three main contributions are provided. The “global minimality” property is shown to hold: the minimization of a given XPath expression can be accomplished by removing pieces of the expression, without having to re-formulate it (as for “general” disjunctive queries). Then, the complexity of the minimization problem is characterized, showing that it is the same as the containment problem. Finally, specific forms of XPath expressions are identified, which can be minimized in polynomial time.
Bit complexity of breaking and achieving symmetry in chains and rings
Authors: Dinitz Yefim , Moran Shlomo , Rajsbaum Sergio
Published: February 2008

We consider a failure-free, asynchronous message passing network with
n
links, where the processors are arranged on a ring or a chain. The processors are identically programmed but have distinct identities, taken from {0, 1,… ,
M
− 1}. We investigate the communication costs of three well studied tasks: Consensus, Leader, and MaxF (finding the maximum identity). We show that in chain and ring topologies, the message complexities of all three tasks are the same. Hence, we study a finer measure of complexity: the number of transmitted
bits
required to solve a task
T
, denoted
BitC
(
T
).

We prove several new lower bounds (and some simple upper bounds) that imply the following results: For the two processors case,
BitC
(Consensus) = 2 and
BitC
(Leader) =
BitC
(MaxF) = 2log
2
M
±
O
(1), where the gap between the lower and upper bounds is almost always 1. For a chain,
BitC
(Consensus) = Θ(
n
),
BitC
(Leader) = Θ(
n
+ log
M
), and
BitC
(MaxF) = Θ(
n
log
M
). For the ring topology, we prove the lower bound of Ω(
n
log
M
) for Leader, and (hence) MaxF.

We consider also a chain where the intermediate processors have no identities. We prove that
BitC
(Leader) = Θ(
n
log
M
), which is equal to
n
times the bit complexity of the problem for two processors. For the specific case when the chain length is even, we prove that
BitC
(Leader) = Θ(
n
), for both above settings. In addition, we show that for any algorithm solving MaxF, there exists an input, for which
every
execution has the bit complexity Ω(
n
log
M
) (this is not the case for Leader).

In our proofs, we use both methods of distributed computing and of communication complexity theory, establishing new links between the two areas.
Undecidability of bisimilarity by defender's forcing
Authors: Jančar Petr , Srba Jivří
Published: February 2008

Stirling [1996, 1998] proved the decidability of bisimilarity on so-called normed pushdown processes. This result was substantially extended by Sénizergues [1998, 2005] who showed the decidability of bisimilarity for regular (or equational) graphs of finite out-degree; this essentially coincides with weak bisimilarity of processes generated by (unnormed) pushdown automata where the
ε
-transitions can only deterministically pop the stack. The question of decidability of bisimilarity for the more general class of so called Type -1 systems, which is equivalent to weak bisimilarity on unrestricted
ε
-popping pushdown processes, was left open. This was repeatedly indicated by both Stirling and Sénizergues. Here we answer the question negatively, that is, we show the undecidability of bisimilarity on Type -1 systems, even in the normed case.

We achieve the result by applying a technique we call Defender's Forcing, referring to the bisimulation games. The idea is simple, yet powerful. We demonstrate its versatility by deriving further results in a uniform way. First, we classify several versions of the undecidable problems for prefix rewrite systems (or pushdown automata) as Π
0
1
-complete or Σ
1
1
-complete. Second, we solve the decidability question for weak bisimilarity on PA (Process Algebra) processes, showing that the problem is undecidable and even Σ
1
1
-complete. Third, we show Σ
1
1
-completeness of weak bisimilarity for so-called parallel pushdown (or multiset) automata, a subclass of (labeled, place/transition) Petri nets.
On the Construction of Practical Key Predistribution Schemes for Distributed Sensor Networks Using Combinatorial Designs
Authors: Lee Jooyoung , Stinson Douglas R.
Published: February 2008

In this paper, we discuss the use of combinatorial set systems (combinatorial designs) in the design of key predistribution schemes (KPSs) for sensor networks. We show that the performance of a KPS can be improved by carefully choosing a certain class of set systems as “key ring spaces”. Especially, we analyze KPSs based on a type of combinatorial design known as a transversal design. We employ two types of transversal designs, which are represented by the set of all linear polynomials and the set of quadratic polynomials (over some finite field), respectively. These KPSs turn out to have significant efficiency in a shared-key discovery phase without degrading connectivity and resiliency.
Energy-efficient dynamic task scheduling algorithms for DVS systems
Authors: Zhuo Jianli , Chakrabarti Chaitali
Published: February 2008

Dynamic voltage scaling (DVS) is a well-known low-power design technique that reduces the processor energy by slowing down the DVS processor and stretching the task execution time. However, in a DVS system consisting of a DVS processor and multiple devices, slowing down the processor increases the device energy consumption and thereby the system-level energy consumption. In this paper, we first use system-level energy consideration to derive the “optimal ” scaling factor by which a task should be scaled if there are no deadline constraints. Next, we develop dynamic task-scheduling algorithms that make use of dynamic processor utilization and optimal scaling factor to determine the speed setting of a task. We present algorithm
duEDF
, which reduces the CPU energy consumption and algorithm
duSYS
and its reduced preemption version,
duSYS_PC
, which reduce the system-level energy. Experimental results on the video-phone task set show that when the CPU power is dominant, algorithm
duEDF
results in up to 45% energy savings compared to the non-DVS case. When the CPU power and device power are comparable, algorithms
duSYS
and
duSYS_PC
achieve up to 25% energy saving compared to CPU energy-efficient algorithm
duEDF
, and up to 12% energy saving over the non-DVS scheduling algorithm. However, if the device power is large compared to the CPU power, then we show that a DVS scheme does not result in lowest energy. Finally, a comparison of the performance of algorithms
duSYS
and
duSYS_PC
show that preemption control has minimal effect on system-level energy reduction.
Task mapping and priority assignment for soft real-time applications under deadline miss ratio constraints
Authors: Manolache Sorin , Eles Petru , Peng Zebo
Published: February 2008

Both analysis and design optimisation of real-time systems has predominantly concentrated on considering hard real-time constraints. For a large class of applications, however, this is both unrealistic and leads to unnecessarily expensive implementations. This paper addresses the problem of task priority assignment and task mapping in the context of multiprocessor applications with stochastic execution times and in the presence of constraints on the percentage of missed deadlines. We propose a design space exploration strategy together with a fast method for system performance analysis. Experiments emphasize the efficiency of the proposed analysis method and optimisation heuristic in generating high-quality implementations of soft real-time systems with stochastic task execution times and constraints on deadline miss ratios.
An agile development methodology applied to embedded control software under stringent hardware constraints
Authors: Cordeiro Lucas , Mar Carlos , Valentin Eduardo , Cruz Fabiano , Patrick Daniel , Barreto Raimundo , Lucena Vicente
Published: February 2008

In recent years, discrete control systems play an important role in the development and advancement of modern civilization and technology. Practically every aspect of our life is affected by some type of control systems. This kind of system maybe classified as an embedded real-time system and requires rigorous methodologies to develop the software that is under stringent hardware constraints. Therefore, the proposed development methodology adapts agile principles and patterns in order to build embedded control systems focusing on the issues related to the system's constraints and safety. Strong unit testing is the foundation of the proposed methodology for ensuring timeliness and correctness. Moreover, platform-based design approach is used to balance costs and time-to-market in view of performance and functionality constraints. We conclude that the proposed methodology reduces significantly the design time and cost as well as leads to better software modularity and reliability.
Don't soil the commons
Authors: Gotterbarn Don
Published: February 2008

In July I was fortunate to attend a Computer Ethics Conference in San Diego. One of the speakers referred to the concept of the 'Tragedy of the Commons'. I realized that a variation concept unfortunately models the ways we use and develop the internet.
Computing capstone projects and the role of failure in education
Authors: Clear Tony
Published: February 2008

We held our end of semester capstone project presentations just the other day. Always an interesting experience, for students, audience and for me in particular as coordinator of our capstone project experience. Our Bachelor of Computer & Information Sciences degree has broadened recently to include several new majors. So now in addition to our traditional software development majors, we have seen a variety of project presentations from students majoring in IT Security, Information Services, Net Centric-computing and a student studying a conjoint degree majoring in accounting and software development. Several teams had a combination of students from these different majors. This of course raises challenges for us in sourcing, coordination and assigning of projects, as well as for supervisors in overseeing the more multi-disciplinary model of learning that these projects bring forth.
What image do CS1/CS2 present to our students?
Authors: Walker Henry M.
Published: February 2008

In my discussions with prospective students and their parents, many or most high school students seem to believe that computer science focuses on some combination of three elements: surfing the Web, playing games, and hacking. Further, these potential students often believe that computing is solitary, mindless button-pushing, and antisocial. In addition, many of these folks have the impression that there are few jobs in the computing industry (most are outsourced), and the few that remain lack the potential for creativity or societal impact.
Pre-college math concepts vs. skills
Authors: Henderson Peter B.
Published: February 2008

Here is some news to bring you up-to-date. I retired from Butler at the end of the spring 2007 semester. So now I am a retired emeritus professor from two institutions: SUNY Stony Brook and Butler University. Accordingly, this has been an interesting summer as I ease into retirement. Before there was always pressure to get summer things done before starting the academic year. Now I find putting lots of them off knowing there is always tomorrow, next week, month, year, etc. The columns I write are also coming a bit more slowly.
Elaborating heuristic reasoning and rigor with mathematical games
Authors: Ginat David
Published: February 2008

Mathematical games arouse enthusiasm and challenge. They usually involve clear and simple rules, with physical, visual, or numerical entities, which raise motivation and intuition. The development of their playing strategies requires both heuristic reasoning and rigor. In order to win, one should recognize and capitalize on number patterns, such as parity and symmetry, as well as invariant patterns of repeated algorithmic actions. The search for patterns involves essential problem solving heuristics, and the validation of devised algorithmic actions requires a rigorous, scientific point of view. While games are known to be stimulating, their utilization in textbooks is very limited, if at all. In this paper, we offer an instructional approach, of using mathematical games, for elaborating fundamental notions that are apparent and relevant already at the very basic levels of computer science (CS) studies. We display our approach, illustrate it, and describe our experience in applying it in class.
The linear twin Towers of Hanoi problem
Authors: Minsker Steven
Published: February 2008

We propose a simple new variation of the Towers of Hanoi problem, in which there are three pegs arranged in a row and there are two stacks (black, white) of n rings each, initially located on the end pegs. The object is to exchange the stacks in accordance with the usual Hanoi rules, and with the additional restriction that rings cannot move directly from end to end. An optimal algorithm is presented, and its performance is analyzed. The problem and its solution are
not
difficult; the purpose of this paper is to present a simple yet interesting exercise in discrete mathematics and recursive algorithms.
An alternative dynamic programming solution for the 0/1 knapsack
Authors: Rolfe Timothy J.
Published: February 2008

The 0/1 knapsack (or knapsack without repetition) has a dynamic programming solution driven by a table in which each item is consecutively considered. The problem can also be approached by generating a table in which the optimal knapsack for each knapsack capacity is generated, modeled on the solution to the integer knapsack (knapsack with repetition) found in Sedgewick [1] and the solution to change-making found in Ciubatii [2].
Computer science
Authors: Cohen Avi , Haberman Bruria
Published: February 2008

The field of computer science has been rapidly developing since its recognition as a stand-alone discipline. The dynamics of the field led to its inadequate public image and posed challenges regarding how to make computer science studies more appealing to students. Recently, computer science has been recognized as a language of natural sciences, and its synergy with these sciences became noteworthy. This paper illuminates another facet of computer science. We call for the acknowledgement of computer science as a
scientific paradigm, which is a language of technology
. The language describes structures, processes, relationships, and communications. We believe that this view expands the responsibility of computer science in the contemporary world and legitimates its status as a basic language that is essential for acquiring scientific and technological literacy.
Learning compiler construction by examples
Authors: de Oliveira Guimarães José
Published: February 2008

In traditional compiler construction courses, each compiler phase is studied in detail before moving on to the next one. This not only places a great distance between theory and practice but also makes the students lose the big picture of the subject. We have been employing a different course format in which the subject is incrementally introduced through ten compilers of increasingly complexity. The first compiler is in fact just a syntax analyzer of a very simple language. The last one is a complete compiler of a Pascal-like language. Students of this course learn how to build compilers faster than the usual.
Complex game development by freshman computer science majors
Authors: Goulding Tom , DiTrolio Rita
Published: February 2008

This case study reveals Daniel Webster College's experience of increasing enrollments dramatically and igniting student enthusiasm for the computer sciences by combining complex game development with innovative classroom management techniques and non traditional student assessments. In this paper we discuss the classroom methods which favor independent study, cooperative learning and teamwork over lectures and individual achievement. This provides the basis for freshmen computer science majors to experience the pressures and motivations found in the game development industry. Those pressures include mandatory independent study, massive knowledge assimilation, rapid product development and tight schedules developing complex gaming systems. Thus, the cachet of complex game development in C# .NET is exploited, but at the same time the development of core programming skills remains the target goal.
Ice hockey and tennis balls
Authors: Beaubouef Theresa , McDowell Patrick
Published: February 2008

This paper investigates issues involved in establishing an undergraduate research program in robotics. We discuss our motivation for such a program, the challenges involved with various aspects of administration and equipment, and our plans for projects for student research. One project deals with programming a robot to play air hockey and another project involves the collection of tennis balls from a tennis court using a coordinated team of robots. Preliminary results hold promise, and we are optimistic about the future of the program.
Planning and evaluating programs in computer science education
Authors: Randolph Justus J.
Published: February 2008

In this paper, I summarize four articles that came about as a result of a special projects grant to develop resources for planning and evaluating CSE programs. The articles include a review of previous K-12 CSE program evaluations, two evaluation and planning models, and a case study in youth participatory program planning in which those models were investigated.
Debugging assistance for novices
Authors: Simon Beth , Fitzgerald Sue , McCauley Renée , Haller Susan , Hamer John , Hanks Brian , Helmick Michael T. , Moström Jan Erik , Sheard Judy , Thomas Lynda
Published: February 2008

This paper reports on the efforts of an ITiCSE 2007 working group with the aim of producing a publicly available, searchable, tagable, Web 2.0-style repository of short debugging videos. This repository may be accessed from http://debug.csi.muohio.edu/. The videos are aimed at novice Java programmers who may need help debugging when none is available (e.g. in the middle of the night before the homework is due). However, it could also be used by instructors of introductory programming. Here we discuss our motivation in creating this repository and detail the process we followed and the products we produced.
A multi-perspective digital library to facilitate integrating teaching research methods across the computing curriculum
Authors: Applin Anne G. , Holz Hilary J. , Joel William , Okoye Ifeyinwa , Deibel Katherine , Grasser Becky , Oates Briony J. , Wood Gwendolyne
Published: February 2008

The computing research methods (CRM) literature is scattered across discourse communities and published in specialty journals and conference proceedings. This dispersion has led to the use of inconsistent terminology when referring to CRM. With no established CRM vocabulary and isolated discourse communities, computing as a field needs to engage in a sense-making process to establish the common ground necessary to support meaningful dialog.

We propose to establish common ground through the construction of the computing research methods multi-perspective digital library (CRM-MPDL), a scholar-produced digital resource for the CRM community. As with its parent design research project on teaching CRM, CRM-MPDL is being developed through iterative and participatory design in an emergent fashion in tandem with the larger CRM community.

For our resource to be viable, we must carefully explore the rich details and nuances of our stakeholder communities and the perspectives they bring to the sense-making process. As a discount alternative to truly having a representative sample of our user population "in the room" with us throughout the design and implementation process, we have implemented a development approach for CRM-MPDL using personas as a means to gain insights and feedback from the target user communities.

For this iteration of the development process, we are concentrating on the needs of the faculty.

In this report, we present our evolving understanding of the project, and seek feedback and input on several key aspects of the theoretical and process models. We then present the framework for the faculty personas, as well as an overview of some of the personas at the time the paper was prepared, in the hopes that we can entice readers to visit the project website to help with the ongoing audit and refinement process. We also give an overview of the content model for CRM-MPDL, which will have evolved (and may even be available as a working prototype) by the time this article appears in print. Finally, we conclude with a current status summary, and issue several specific calls for participation in the ongoing work of the project.
KDD Cup 2007 task 1 winner report
Authors: Kurucz Miklós , Benczúr András A. , Kiss Tamás , Nagy István , Szabó Adrienn , Torma Balázs
Published: February 2008

KDD Cup 2007 focuses on predicting aspects of movie rating behavior. We present our prediction method for Task 1 "Who Rated What in 2006" where the goal is to predict which users rated which movies in 2006. We use the combination of the following methods, listed in the order of their accuracy:

• The predicted number of ratings for each movie based on time series analysis, also using movie and DVD release dates and movie series detection by the edit distance of the titles.

• The predicted number of ratings by each user by using the fact that ratings were sampled proportional to the margin.

• The low rank approximation of the 0-1 matrix of known user-movie pairs with rating.

• Prediction by using the movie-movie similarity matrix.

• Association rules obtained by frequent sequence mining of user ratings considered as ordered itemsets.

By combining the predictions by linear regression we obtained a prediction with root mean squared error 0.256. The first runner up result was 0.263 while a pure all zeroes prediction already gives 0.279, indicating the hardness of the task.
Predicting who rated what in large-scale datasets
Authors: Liu Yan , Kou Zhenzhen
Published: February 2008

KDD Cup 2007 focuses on movie rating behaviors. The goal of the task "Who Rated What" is to predict whether "existing" users will review "existing" movies in the future. We cast the task as a link prediction problem and address it via a simple classification approach. Compared with other applications for link prediction, there are two major challenges in our task: (1) the huge size of the Netflix data; (2) the prediction target is complicated by many factors, such as a general decrease of interest in old movies and more tendency to review more movies by Netflix users due to the success of the internet DVD rental industries. We address the first challenge by "selective" subsampling and the second by combining information from the review scores, movie contents and graph topology effectively.
Data mining and audience intelligence for advertising
Authors: Li Ying , Surendran Arun C. , Shen Dou
Published: February 2008

Growth in the global advertising industry - especially the recent rapid growth in online advertising - has generated large volumes of data, bringing along with it many challenging data mining problems. Researchers from various disciplines have brought their expertise to solve these exciting problems, leading to a plethora of novel applications and new algorithms. We strongly felt that we needed a forum where data mining researchers and practitioners, from both academia and the industry, could come together to share their experience on advertising. To this end, we organized
ADKDD 2007
1
, the First International Workshop on Data Mining and Audience Intelligence for Advertising, in conjunction with KDD 2007 at San Jose, California, USA. In this report, we will present a summary of the workshop.
Corticotropin-releasing factor type 1 receptors mediate the visceral hyperalgesia induced by repeated psychological stress in rats
Authors: Larauche Muriel , Bradesi Sylvie , Million Mulugeta , McLean Peter , Taché Yvette , Mayer Emeran A. , McRoberts James A.
Published: February 2008

Visceral hypersensitivity has been implicated as an important pathophysiological mechanism in functional gastrointestinal disorders. In this study, we investigated whether the sustained visceral hyperalgesia induced by repeated psychological stress in rats involves the activation of CRF1 signaling system using two different antagonists. Male Wistar rats were exposed to 10 consecutive days of water avoidance stress (WAS) or sham stress for 1 h/day, and the visceromotor response to phasic colorectal distension (CRD) was assessed before and after the stress period. Animals were injected subcutaneously with the brain penetrant CRF1 antagonist, CP-154,526, acutely (30 min before the final CRD) or chronically (via osmotic minipump implanted subcutaneously, during stress) or with the peripherally restricted, nonselective CRF1 and CRF2 antagonist, astressin, chronically (15 min before each stress session). Repeated WAS induced visceral hypersensitivity to CRD at 40 and 60 mmHg. CP-154,526 injected acutely significantly reduced stress-induced visceral hyperalgesia at 40 mmHg but not at 60 mmHg. Chronic subcutaneous delivery of astressin reduced the stress-induced visceral hyperalgesia to baseline at all distension pressures. Interestingly, chronically administered CP-154,526 eliminated hyperalgesia and produced responses below baseline at 40 mmHg and 60 mmHg, indicating a hypoalgesic effect of the compound. These data support a major role for CRF1 in both the development and maintenance of visceral hyperalgesia induced by repeated stress and indicate a possible role of peripheral CRF receptors in such mechanisms.
Seasonal acclimatization of brain lipidome in a eurythermal fish (Carassius carassius) is mainly determined by temperature
Authors: Käkelä Reijo , Mattila Minja , Hermansson Martin , Haimi Perttu , Uphoff Andreas , Paajanen Vesa , Somerharju Pentti , Vornanen Matti
Published: February 2008

Crucian carp ( Carassius carassius) is an excellent vertebrate model for studies on temperature adaptation in biological excitable membranes, since the species can tolerate temperatures from 0 to +36°C. To determine how temperature affects the lipid composition of brain, the fish were acclimated for 4 wk at +30, +16, or +4°C in the laboratory, or seasonally acclimatized individuals were captured from the wild throughout the year (temperature = +1 to +23°C), and the brain glycerophospholipid and sphingolipid compositions were analyzed in detail by electrospray-ionization mass spectrometry. Numerous significant temperature-related changes were found in the molecular species composition of the membrane lipids. The most notable and novel finding was a large (∼3-fold) increase of the di-22:6n-3 phosphatidylserine and phosphatidylethanolamine species in the cold. Since the increase of 22:6n-3 in the total fatty acyl pool of the brain was small, the formation of di-22:6n-3 aminophospholipid species appears to be a specific adaptation to low temperature. Such highly unsaturated species could be needed to maintain adequate membrane fluidity in the vicinity of transporters and other integral membrane proteins. Plasmalogens increased somewhat at higher temperatures, possibly to protect membranes against oxidation. The modifications of brain lipidome during the 4-wk laboratory acclimation were, in many respects, similar to those found in the wild, which indicates that the seasonal changes observed in the wild are temperature dependent rather than induced by other environmental factors.
Receptor‐Drug Interaction: Europium Employment for Studying the Biochemical Pathway of G‐Protein‐Coupled Receptor Activation
Authors: Antonio Colabufo Nicola , Grazia Perrone Maria , Marialessandra Contino , Francesco Berardi , Roberto Perrone
Published: February 2008

In medicinal chemistry field, the biochemical pathways, involved in 7‐transmembrane domains G‐protein coupled receptors (GPCRs) activation, are commonly studied to establish the activity of ligands towards GPCRs. The most studied steps are the measurement of activated GTP‐αsubunit and stimulated intracellular cAMP. At the present, many researchers defined agonist or antagonist activity of potential GPCRs drugs employing [35S]GTPγS or [3H]cAMP as probes. Recently, the corresponding lanthanide labels Eu‐GTP and Eu‐cAMP as alternative to radiochemicals have been developed because they are highly sensitive, easy to automate, easily synthesized, they display a much longer shelf‐life and they can be used in multilabel experiments. In the present review, the receptor‐drug interaction by europium employment for studying the biochemical pathway of GPCR activation has been focused. Moreover, comparative studies between lanthanide label probes and the corresponding radiolabeled compounds have been carried out.
Fine Structure of Dark Energy and New Physics
Authors: Jejjala Vishnu , Kavic Michael , Minic Djordje
Published: February 2008

Following our recent work on the cosmological constant problem, in this letter we make a specific proposal regarding the fine structure (i.e., the spectrum) of dark energy. The proposal is motivated by a deep analogy between the blackbody radiation problem, which led to the development of quantum theory, and the cosmological constant problem, for which we have recently argued calls for a conceptual extension of the quantum theory. We argue that the fine structure of dark energy is governed by a Wien distribution, indicating its dual quantum and classical nature. We discuss observational consequences of such a picture of dark energy and constrain the distribution function.
Blue-Emitting Small Silica Particles Incorporating ZnSe-Based Nanocrystals Prepared by Reverse Micelle Method
Authors: Ando Masanori , Li Chunliang , Yang Ping , Murase Norio
Published: February 2008

ZnSe-based nanocrystals (ca. 4-5 nm in diameter) emitting in blue region (ca. 445 nm) were incorporated in spherical small silica particles (20–40 nm in diameter) by a reverse micelle method. During the preparation, alkaline solution was used to deposit the hydrolyzed alkoxide on the surface of nanocrystals. It was crucially important for this solution to includeZn2+ions and surfactant molecules (thioglycolic acid) to preserve the spectral properties of the final silica particles. This is because these substances in the solution prevent the surface of nanocrystals from deterioration by dissolution during processing. The resultant silica particles have an emission efficiency of 16% with maintaining the photoluminescent spectral width and peak wavelength of the initial colloidal solution.
Monotone Iterative Technique for Partial Dynamic Equations of First Order on Time Scales
Authors: Wang Peiguang , Li Ping
Published: February 2008

This work is concerned with the monotone iterative technique for partial dynamic equations of first order on time scales and for this purpose, the existence, uniqueness, and comparison results are also established.
On New Extensions of Hilbert′s Integral Inequality
Authors: Leping He , Mingzhe Gao , Yu Zhou
Published: February 2008

It is shown that some new extensions of Hilbert′s integral inequality with parameter λ(λ > 1/2) can be established by introducing a proper weight function. In particular, when λ = 1, a refinement of Hilbert′s integral inequality is obtained. As applications, some new extensions of Widder′s inequality and Hardy‐Littlewood′s inequality are given.
Investigation of Zinc bis(1,4-didecylbenzo)-bis(2,3-pyrido) Porphyrazine for Application as Photosensitizer in Photodynamic Therapy of Cancer
Authors: Sakamoto Keiichi , Ohno-Okumura Eiko , Kato Taku , Watanabe Masaki , Cook Michael J.
Published: February 2008

The phthalocyanine analogue containing nonperipheral long alkyl-substituted benzenoid rings and pyridine rings, zinc bis(1,4-didecylbenzo)-bis(2,3-pyrido) porphyrazine, was synthesized. Zinc bis(1,4-didecylbenzo)-bis(2,3-pyrido) porphyrazine reacted with dimethyl sulfate and monochloroacetic acid to produce their quaternized products and diethyl sulfate to produce the sulfo-substituted products. All quaternized and sulfo-substituted showed amphiphilic character. Identical peaks in cyclic voltammograms appeared for these products before and after quaternization. During the evaluation of zinc bis(1,4-didecylbenzo)-bis(2,3-pyrido) porphyrazine for its photodynamic therapy of cancer (PDT) efficacy by cancer cell culture, the light exposed dimethyl sulfate quaternized zinc bis(1,4-didecylbenzo)-bis(2,3-pyrido) porphyrazines in IU-002 cells produce cell disruption that can be detected as a decrease in fluorescence.
T-Stability of Picard Iteration in Metric Spaces
Authors: Qing Yuan , Rhoades B.E.
Published: February 2008

We establish a general result for the stability of Picard's iteration. Several theorems in the literature are obtained as special cases.
Parabolic Pulse Generation Using Tapered Microstructured Optical Fibres
Authors: Vukovic Natasha , Broderick Neil G. R. , Poletti Francesco
Published: February 2008

This paper presents a numerical study of parabolic pulse generation in tapered microstructured optical fibres (MOFs). Based on our results and the algorithms presented, one can determine the linear taper profile (starting and finishing pitch values and taper length) needed to achieve parabolic pulse shaping of an initial Gaussian pulse shape with different widths and powers. We quantify the evolution of the parabolic pulse using the misfit parameter and show that it is possible to reach values significantly better than those obtained by a step index fibre.
On Gap Functions for Quasi‐Variational Inequalities
Authors: Taji Kouichi
Published: February 2008

For variational inequalities, various merit functions, such as the gap function, the regularized gap function, the D‐gap function and so on, have been proposed. These functions lead to equivalent optimization formulations and are used to optimization‐based methods for solving variational inequalities. In this paper, we extend the regularized gap function and the D‐gap functions for a quasi‐variational inequality, which is a generalization of the variational inequality and is used to formulate generalized equilibrium problems. These extensions are shown to formulate equivalent optimization problems for quasi‐variational inequalities and are shown to be continuous and directionally differentiable.
On Blind MIMO System Identification Based on Second‐Order Cyclic Statistics
Authors: Sabri K. , El Badaoui M. , Guillet F. , Adib A. , Aboutajdine D.
Published: February 2008

This letter introduces a new frequency domain approach for either MIMO System Identification or Source Separation of convolutive mixtures in cyclostationary context. We apply the joint diagonalization algorithm to a set of cyclic spectral density matrices of the measurements to identify the mixing system at each frequency up to permutation and phase ambiguity matrices. An efficient algorithm to overcome the frequency dependent permutations and to recover the phase, even for non‐minimum‐phase channels, based on cyclostationarity is also presented. The new approach exploits the fact that each input has a different and specific cyclic frequency. A comparison with an existing MIMO method is proposed.
The Behavior of Positive Solutions of a Nonlinear Second‐Order Difference Equation
Authors: Stević Stevo , Berenhaut Kenneth S.
Published: February 2008

This paper studies the boundedness, global asymptotic stability, and periodicity of positive solutions of the equation xn = f(xn−2)/g(xn−1), n ∈ ℕ0, where f, g ∈ C[(0, ∞), (0, ∞)]. It is shown that if f and g are nondecreasing, then for every solution of the equation the subsequences {x2n} and {x2n−1} are eventually monotone. For the case when f(x) = α + βx and g satisfies the conditions g(0) = 1, g is nondecreasing, and x/g(x) is increasing, we prove that every prime periodic solution of the equation has period equal to one or two. We also investigate the global periodicity of the equation, showing that if all solutions of the equation are periodic with period three, then f(x) = c1/x and g(x) = c2x, for some positive c1 and c2.
Bifurcation for Second‐Order Hamiltonian Systems with Periodic Boundary Conditions
Authors: Faraci Francesca , Iannizzotto Antonio
Published: February 2008

Through variational methods, we study nonautonomous systems of second‐order ordinary differential equations with periodic boundary conditions. First, we deal with a nonlinear system, depending on a function u, and prove that the set of bifurcation points for the solutions of the system is not σ‐compact. Then, we deal with a linear system depending on a real parameter λ > 0 and on a function u, and prove that there exists λ∗ such that the set of the functions u, such that the system admits nontrivial solutions, contains an accumulation point.
Computation of Positive Realizations for Given Impulse Response Matrices of Discrete‐Time Systems
Authors: Kaczorek Tadeusz
Published: February 2008

A method is presented for computation of positive realizations for given impulse response matrices of discrete‐time systems. Sufficient conditions for the existence of positive realizations are established and a procedure for computation of positive realizations for given impulse response matrices is proposed.
Bayesian Inference and Markov Chain Monte Carlo Sampling to Reconstruct a Contaminant Source on a Continental Scale
Authors: Delle Monache Luca , Lundquist Julie K. , Kosović Branko , Johannesson Gardar , Dyer Kathleen M. , Aines Roger D. , Chow Fotini K. , Belles Rich D. , Hanley William G. , Larsen Shawn C. , Loosmore Gwen A. , Nitao John J. , Sugiyama Gayle A. , Vogt Philip J.
Published: February 2008

A methodology combining Bayesian inference with Markov chain Monte Carlo (MCMC) sampling is applied to a real accidental radioactive release that occurred on a continental scale at the end of May 1998 near Algeciras, Spain. The source parameters (i.e., source location and strength) are reconstructed from a limited set of measurements of the release. Annealing and adaptive procedures are implemented to ensure a robust and effective parameter-space exploration. The simulation setup is similar to an emergency response scenario, with the simplifying assumptions that the source geometry and release time are known. The Bayesian stochastic algorithm provides likely source locations within 100 km from the true source, after exploring a domain covering an area of approximately 1800 km × 3600 km. The source strength is reconstructed with a distribution of values of the same order of magnitude as the upper end of the range reported by the Spanish Nuclear Security Agency. By running the Bayesian MCMC algorithm on a large parallel cluster the inversion results could be obtained in few hours as required for emergency response to continental-scale releases. With additional testing and refinement of the methodology (e.g., tests that also include the source geometry and release time among the unknown source parameters), as well as with the continuous and rapid growth of computational power, the approach can potentially be used for real-world emergency response in the near future.
Higher Risk of Common Mental Disorders After Experiencing Physical Violence in Rio De Janeiro, Brazil: the Pró-Saúde Study
Authors: Lopes Claudia S. , Faerstein Eduardo , Chor Dóra , Werneck Guilherme L.
Published: February 2008

Background: In Brazil, violence is a major public health problem. However, up until now, the extent to which violence acts as a risk factor for mental disorders has not been investigated prospectively.

Aims: We determined the risk of common mental disorders (CMD) associated with personal experience with physical violence (PV).

Methods: A cohort of 3253 public employees in Rio de Janeiro completed questionnaires that measured CMD (GHQ-12), experience with PV and stressful life events (SLE).

Results: After adjusting for age, income and SLE, those who experienced PV in either 1999 or 2001 and those who experienced PV in both years had, respectively, 1.2-fold (95% CI; 1.0—1.4) and 2.1-fold (1.6—2.6) increased risks of CMD.

Conclusion: Direct exposure to violence may act cumulatively on the risk of developing CMD. The absence of association for reporting CMD both in 1999 and 2001 suggests that other determinants may be more relevant for chronic mental disorders.