Showing papers by "Turku Centre for Computer Science published in 2006"

Why complicate things?: introducing programming in high school using Python

Abstract: Deciding what to teach novices about programming and what programming language to use is a common topic for debate. Should an industry relevant programming language be taught, or should a language designed for teaching novices be used? Typically, these questions are raised at university level, but in this paper we address them from a high school perspective.We present a case study with a twofold goal: (1) examining how programming can be introduced at high school level, and (2) evaluating how suitable the programming language Python is to support both teachers and learners in this process. During the school year 2004/2005, an introductory programming course was given to four student groups in two different high schools. The students enjoyed programming and learnt to think in terms of re-use and interfaces. In addition, we found that many features of Python facilitated both teaching and learning (for instance, a simple and flexible syntax, immediate feedback, easy-to-use modules and strict requirements on proper indentation).Our findings support results from previous studies in that students have difficulties in dealing with abstract concepts - even though the syntax for implementing these is simple. In addition, compared to university students, high school students are young and have necessarily not yet developed the writing skills required for producing proper documentation. The course was designed to be well suited for high school students in general, but still all participants were boys. Since high schools should provide all-round learning to all students, we, as do all computer science teachers, face the challenge of making programming more appealing to girls.

What about a simple language? Analyzing the difficulties in learning to program

Abstract: In this paper, we present the results from a two-part study. We analyze 60 programs written by novice programmers aged 16 – 19 after their first programming course, in either Java or Python. The aim is to find difficulties independent of the language used, and such originating from the language. Second, we analyze the transition from a “simple” language to a more “advanced” one, by following up on eight students, who learned programming in Python before moving on to Java. Our results suggest that a simple language gives rise to fewer syntax errors as well as logic errors. The qualitative part of our study did not reveal any disadvantages from having learned to program in a simple language when moving on to a more complex one. This suggests that not only can a simple language be used when introducing programming as a general skill, but also when providing basic skills to future professionals in the field.

Physicians' acceptance of mobile communication technology: an exploratory study

Abstract: The study aims to contribute to the research on technology acceptance behaviour of professional physicians by extending its theoretical validity and empirical applicability in a new mobile communication technology context. We propose and empirically examine a research model using data collected from 151 physicians working in the healthcare sector in Finland; with the aid from previous research into the adoption of information systems, mainly TAM, UTAUT and PIIT. The results suggest that our proposed model could provide adequate explanations for physicians' intentions to use the mobile system (Nagelkerke R² = 0.654). The important determinants of physicians' behavioural intentions in early exposure to the mobile system are: perceived usefulness, the interaction effects of PIIT and age on ease of use, and of age on compatibility. Gender and hands-on experience of the system have different effect on physicians' perceptions of the system.

Lexical adaptation of link grammar to the biomedical sublanguage: a comparative evaluation of three approaches

Abstract: We study the adaptation of Link Grammar Parser to the biomedical sublanguage with a focus on domain terms not found in a general parser lexicon. Using two biomedical corpora, we implement and evaluate three approaches to addressing unknown words: automatic lexicon expansion, the use of morphological clues, and disambiguation using a part-of-speech tagger. We evaluate each approach separately for its effect on parsing performance and consider combinations of these approaches. In addition to a 45% increase in parsing efficiency, we find that the best approach, incorporating information from a domain part-of-speech tagger, offers a statistically significant 10% relative decrease in error. When available, a high-quality domain part-of-speech tagger is the best solution to unknown word issues in the domain adaptation of a general parser. In the absence of such a resource, surface clues can provide remarkably good coverage and performance when tuned to the domain. The adapted parser is available under an open-source license.

Quality classification of tandem mass spectrometry data

Abstract: Motivation: Peptide identification by tandem mass spectrometry is an important tool in proteomic research. Powerful identification programs exist, such as SEQUEST, ProICAT and Mascot, which can relate experimental spectra to the theoretical ones derived from protein databases, thus removing much of the manual input needed in the identification process. However, the time-consuming validation of the peptide identifications is still the bottleneck of many proteomic studies. One way to further streamline this process is to remove those spectra that are unlikely to provide a confident or valid peptide identification, and in this way to reduce the labour from the validation phase. Results: We propose a prefiltering scheme for evaluating the quality of spectra before the database search. The spectra are classified into two classes: spectra which contain valuable information for peptide identification and spectra that are not derived from peptides or contain insufficient information for interpretation. The different spectral features developed for the classification are tested on a real-life material originating from human lymphoblast samples and on a standard mixture of 9 proteins, both labelled with the ICAT-reagent. The results show that the prefiltering scheme efficiently separates the two spectra classes. Availability: The software tools are available on request from the authors. Contact: jussi.salmi@it.utu.fi Supplementary information: The Mascot ion score distributions and the C4.5 classification rules can be found at address http://staff.cs.utu.fi/staff/jussi.salmi/Supplementary_material.pdf

A Standalone OCR System for Mobile Cameraphones

Abstract: In optical character recognition (OCR), visible characters appearing as images (i.e. on paper) are recognized as symbolic characters and stored in a computer?s memory or similar device. The purpose of this work is to find whether current mobile cameraphones are able to run OCR software without relying on dedicated hardware or facilities provided by the network. This article describes a simple OCR system that was implemented in Symbian C++ to be run on a stock Nokia 6630 camera-phone. The system is limited to recognizing English capital letters printed in black, against a white background. The opportunities and hardships related to bringing OCR to run on mobile platforms having image capturing capability are also discussed in more general terms.

Error Models for the Transport Stream Packet Channel in the DVB-H Link Layer

Abstract: Digital video broadcasting for hand held terminals (DVB-H) is a broadcast system designed for high-speed data transmission in highly dispersive mobile channel conditions. In this paper, methods of reproducing the statistical properties of measured DVB-H packet error traces are presented. Statistical and finite-state modeling approaches are found to be suitable for simulating the error performance of a DVB-H system operating in typical urban channel conditions. Evaluation of these models focuses on the accuracy of the models in replicating the high-order statistical properties of measured DVB-H transport stream error traces. Also, the effect of these error statistics on the DVB-H link layer frame error rate is considered.

On Some Problems of Mateescu Concerning Subword Occurrences

Abstract: The paper investigates inference based on quantities |W|$_u$, the number of occurrences of a word u as a scattered subword of W. Parikh matrices recently introduced are useful tools for such investigations. We introduce and study universal languages for Parikh matrices. We also obtain results concerning the inference from numbers |W|$_u$ to W, as well as from certain entries of a Parikh matrix to other entries.

Refinement algebra with operators for enabledness and termination

Abstract: Refinement algebras are abstract algebras for reasoning about programs in a total-correctness framework. We extend a reduct of von Wright's demonic refinement algebra with two operators for modelling enabledness and termination of programs. We show how the operators can be used for expressing relations between programs and apply the algebra to reasoning about action systems.

Grouping and sequencing PCB assembly jobs with minimum feeder setups

Abstract: Printed circuit boards are manufactured in automated assembly lines, where high-speed placement machines put components on the boards. These machines are frequently bottlenecks in the production. This is true especially in high-mix low-volume environments, where time consuming setup operations of the machines have to be done repeatedly. Therefore, one can improve productivity with a proper setup strategy. The most popular strategies are the so-called group setup strategy and minimum setup strategy. In this paper, we consider the machine setup problem as a combination of a job grouping problem and a minimum setup problem. We formulate this joint problem as an Integer Programming model, where the objective is to minimize the weighted sum of the number of setup occasions and the total number of component feeder changes. We also present and evaluate hybrid algorithms based on both grouping and minimum setup heuristics. The best results are achieved by a method which uses both these strategies simultaneously.

Modelling Simple Operations for Gene Assembly

Abstract: The intramolecular model (Ehrenfeucht et al, 2001) for gene assembly in ciliates considers three operations, ld, hi, and dlad that can assemble any micronuclear gene pattern through folding and recombination: the molecule is folded so that two occurrences of a pointer (short nucleotide sequence) get aligned and then the sequence is rearranged through recombination of pointers. In general, the sequence rearranged by one operation can be arbitrarily long and may consist of many coding and non-coding blocks. We consider in this paper some restricted variants of the three operations, where only one coding block is rearranged at a time. We present in this paper the molecular model of these simple operations. We also introduce a mathematical model for the simple operations, on three levels of abstractions: MDS descriptors, signed permutations, and signed double occurrence strings. Interestingly, we show that simple assemblies possess rather involved properties: a gene pattern may have both successful and unsuccessful assemblies and also more than one successful strategy. TUCS Laboratory Computational Biomodelling Discrete Mathematics for Information Technology

Secret Sharing Schemes with Nice Access Structures

Abstract: Secret sharing schemes, introduced by Blakley and Shamir independently in 1979, have a number of applications in security systems. One approach to the construction of secret sharing schemes is based on coding theory. In principle, every linear code can be used to construct secret sharing schemes. But only well structured linear codes give secret sharing schemes with nice access structures in the sense that every pair of participants plays the same role in the secret sharing. In this paper, we construct a class of good linear codes, and use them to obtain a class of secret sharing schemes with nice access structures.

A Novel Algorithm for Decapsulation and Decoding of DVB-H Link Layer Forward Error Correction

Abstract: DVB-H, which is an amendment of DVB-T, offers reliable high data rate reception for mobile handheld and battery-powered devices. A link layer with error correction is defined to work on top of the DVB-T physical layer. The DVB-H standard suggests to use Reed-Solomon coding combined with cyclic redundancy check error detection as the link layer forward error correction. Drawbacks of the decoding solution have been recognized in previous research. This paper presents a novel algorithm for decapsulation and decoding at DVB-H link layer. The algorithm is based on information provided in the transport stream packet headers and requires no changes to the DVB-H standard.

Impacts of physicians' usage of a mobile information system.

Abstract: Healthcare professionals are increasingly using handheld devices in their practice. The applications for the handhelds are numerous and their usage contexts and environments vary. But the impact these mobile systems have on physicians' work has been somewhat unclear. This paper sets out to explain the impacts of a mobile information system by presenting findings from an interview study conducted on users of a medical information system running on a Nokia 9210 Communicator. The impact on the work routines of the users was rather limited, despite the generally positive attitude towards the system. The actual usage patterns and the settings in which the system is used vary, and along with these the perceived impacts of the system on the work habits and the routines of the users.

Subword conditions and subword histories

Abstract: This paper introduces the notion of a subword condition and investigates languages defined by them. The special case, where the language reduces to one word, concerns the inference of a sequence from its subsequences. We obtain various characterization and decidability results for languages defined by subword conditions. The results contribute to the theory of Parikh matrices and arithmetizing the study of words. An important notion from early automata theory, that of a quasi-uniform event, plays a central role in our characterization.

An energy consumption model for an embedded java virtual machine

Abstract: In this paper we establish a general framework for estimating the energy consumption of an embedded Java virtual machine (JVM). We have designed a number of experiments to find the constant overhead of the Virtual Machine and establish an energy consumption cost for individual Java Opcodes. The results show that there is a basic constant overhead for every Java program, and that a subset of Java opcodes have an almost constant energy cost. We also show that memory access is a crucial energy consumption component.

An energy consumption model for an embedded java virtual machine

Abstract: In this paper we establish a general framework for estimating the energy consumption of an embedded Java virtual machine (JVM). We have designed a number of experiments to find the constant overhead of the Virtual Machine and establish an energy consumption cost for individual Java Opcodes. The results show that there is a basic constant overhead for every Java program, and that a subset of Java opcodes have an almost constant energy cost. We also show that memory access is a crucial energy consumption component.

Parallel communicating Watson-Crick automata systems

Abstract: Watson-Crick automata are finite state automata working on double-stranded tapes, introduced to investigate the potential of DNA molecules for computing. In this paper we introduce the concept of parallel communicating Watson-Crick automata systems. It consists of several Watson-Crick finite automata parsing independently the same input and exchanging information on request, by communicating states to each other. We investigate the computational power of these systems and prove that they are more powerful than classical Watson-Crick finite automata, but still accepting at most context-sensitive languages. Moreover, if the complementarity relation is injective, then we obtain that this inclusion is strict. For the general case, we also give some closure properties, as well as a characterization of recursively enumerable languages based on these systems.

Managing the change process of the post-merger enterprise systems integration: a case study

Abstract: Both post-merger integration and the implementation of an enterprise system (ES) are sources of radical change in a company's life cycle. This paper builds on a business process change model for enterprise resource planning implementation and integrates into it M&A issues, issues related to company expertise and resources, and factors related to software and vendor. The case study reveals that elements of each item in the model play a role in the post-merger ES integration processes and emphasises good-quality ES integration management.

Locality-convolution kernel and its application to dependency parse ranking

Abstract: We propose a Locality-Convolution (LC) kernel in application to dependency parse ranking. The LC kernel measures parse similarities locally, within a small window constructed around each matching feature. Inside the window it makes use of a position sensitive function to take into account the order of the feature appearance. The similarity between two windows is calculated by computing the product of their common attributes and the kernel value is the sum of the window similarities. We applied the introduced kernel together with Regularized Least-Squares (RLS) algorithm to a dataset containing dependency parses obtained from a manually annotated biomedical corpus of 1100 sentences. Our experiments show that RLS with LC kernel performs better than the baseline method. The results outline the importance of local correlations and the order of feature appearance within the parse. Final validation demonstrates statistically significant increase in parse ranking performance.

On the frequency of letters in morphic sequences

Abstract: A necessary and sufficient criterion for the existence and value of the frequency of a letter in a morphic sequence is given. This is done using a certain incidence matrix associated with the morphic sequence. The characterization gives rise to a simple if-and-only-if condition that all letter frequencies exist.

On two dually nondeterministic refinement algebras

Abstract: A dually nondeterministic refinement algebra with a negation operator is proposed. The algebra facilitates reasoning about total-correctness preserving program transformations and nondeterministic programs. The negation operator is used to express enabledness and termination operators through a useful explicit definition. As a small application, a property of action systems is proved employing the algebra. A dually nondeterministic refinement algebra without the negation operator is also discussed.

Integration of DFDs into a UML-based Model-driven Engineering Approach

Abstract: The main aim of this article is to discuss how the functional and the object-oriented views can be inter-played to represent the various modeling perspectives of embedded systems. We discuss whether the object-oriented modeling paradigm, the predominant one to develop software at the present time, is also adequate for modeling embedded software and how it can be used with the functional paradigm. More specifically, we present how the main modeling tool of the traditional structured methods, data flow diagrams, can be integrated in an object-oriented development strategy based on the unified modeling language. The rationale behind the approach is that both views are important for modeling purposes in embedded systems environments, and thus a combined and integrated model is not only useful, but also fundamental for developing complex systems. The approach was integrated in a model-driven engineering process, where tool support for the models used was provided. In addition, model transformations have been specified and implemented to automate the process. We exemplify the approach with an IPv6 router case study.