The skewness of computer science

Computer science is a relatively young discipline combining science, engineering, and mathematics. The main flavors of computer science research involve the theoretical development of conceptual models for the different aspects of computing and the more applicative building of software artifacts and assessment of their properties. In the computer science publication culture, conferences are an important vehicle to quickly move ideas, and journals often publish deeper versions of papers already presented at conferences. These peculiarities of the discipline make computer science an original research field within the sciences, and, therefore, the assessment of classical bibliometric laws is particularly important for this field. In this paper, we study the skewness of the distribution of citations to papers published in computer science publication venues (journals and conferences). We find that the skewness in the distribution of mean citedness of different venues combines with the asymmetry in citedness of articles in each venue, resulting in a highly asymmetric citation distribution with a power law tail. Furthermore, the skewness of conference publications is more pronounced than the asymmetry of journal papers. Finally, the impact of journal papers, as measured with bibliometric indicators, largely dominates that of proceeding papers.     

Beyond intelligent tutoring systems: Situations,interactions, processes and affordances

The idea of an intelligentsystem to support learning has been epitomisedby that of an intelligent tutoring system(ITS). However, ITSs are, in fact, just aparticular kind of intelligent system tosupport learning whose components reflect thevalues of the particular view that ITSsemphasise in regard to the nature of knowledge,learning and teaching, which have led to anarchitecture that focuses on representing theknowledge to be learned (domain model),inferring the learner's knowledge (learnermodel), and planning instructional steps to thelearner (teaching model). On the other hand,other views of learning may lead to differentneeds in terms of knowledge representation,reasoning, and decision making capabilities inthe intelligent systems that support them.Constructivist views, for example, emphasisedifferent values and may require an entirelydifferent architecture of intelligent system tosupport its philosophy of learning. This paperpresents an architecture of an intelligentsystem to support learning that is able toaddress the issues that arise fromconstructivist theories of learning in a waythat, rather than opposing to the standard ITSarchitecture, characterises a broader view inall its components which can be appropriatelyattuned to address the issues of particularphilosophies.     

Situations,interactions, processes and affordances: A response

This is a brief response to thecommentaries provided by Young, DePalma andGarrett and by Azevedo on our original paper(Akhras & Self, this issue). In this responsewe elaborate on the aims of ourconceptualization, focussing on the nature ofaffordances and situations.     

Testing the cluster hypothesis in distributed information retrieval

How to merge and organise query results retrieved from different resources is one of the key issues in distributed information retrieval. Some previous research and experiments suggest that cluster-based document browsing is more effective than a single merged list. Cluster-based retrieval results presentation is based on the cluster hypothesis, which states that documents that cluster together have a similar relevance to a given query. However, while this hypothesis has been demonstrated to hold in classical information retrieval environments, it has never been fully tested in heterogeneous distributed information retrieval environments. Heterogeneous document representations, the presence of document duplicates, and disparate qualities of retrieval results, are major features of an heterogeneous distributed information retrieval environment that might disrupt the effectiveness of the cluster hypothesis. In this paper we report on an experimental investigation into the validity and effectiveness of the cluster hypothesis in highly heterogeneous distributed information retrieval environments. The results show that although clustering is affected by different retrieval results representations and quality, the cluster hypothesis still holds and that generating hierarchical clusters in highly heterogeneous distributed information retrieval environments is still a very effective way of presenting retrieval results to users.     

Hermeneutics and Science Education: The role of history of science

Eger's contribution towards a reapprochment of Hermeneutics, Science and Science Education is very welcome. His focus on the problem of misconceptions is relevant. All the same in our opinion some not minor points need a clarification. We will try to argue that: a) Hermeneutics cannot be reduced to a semantical interpretation of science texts; its phenomenological aspects have to be taken in account. b) Science has an unavoidable historical dimension; original papers and advanced textbooks are the real depositaries of scientific research. Standard textbooks are a caricature not worth it of a hermeneutical analysis. c) A parallelism can be traced between two dicothomies: the lifeworld of hermeneutics and the scienceworld of epistemology on one side and the extraordinary and the normal science on the other. d) For an overcoming of the misconceptions' problem we propose that the previous dicothomies be bridged through a hermeneutical phenomenological approach to science education that stresses the alternative, historical interpretations of natural phenomena.     

From planning to mature: On the success of open source projects

Open source is an example of user-centric innovation initiated by an individual or group of users to satisfy their specific needs; the more a software evolves towards a stable release able to address the requirements of its developers, the more successful the project. In this paper we use a large data-set obtained from SourceForge.net to estimate the relationship between a series of different characteristics of OS projects and the probability of evolution of the source code from a preliminary release to a mature version. We show that while projects distributed under highly restrictive licensing terms (GPL) have a significantly smaller probability of reaching a stable release, applications towards sophisticated users have a larger probability of evolving in the development status. Interestingly, we find that the size of the “community of developers” increases the chances of progress but this effect decreases as the community gets larger, a signal of possible coordination problems.     

Museum Heroes All: The Pavia Approach to School-Science Museum Interactions

To improve on the classic school trip to the museum and the traditional distinctions between formal and informal learning, every year we run a project where the schools (first the teachers and then the pupils) are actively involved right from the very first stages of planning. The various projects realised so far involve schools with children of different age levels, from kindergarten to high school, and aim to provide a rewarding museum experience for each level. The various phases of each project follow a timeline where the specific roles of each group of actors is set out. All our projects rely extensively on history of science, but in a number of ways: using primary and secondary sources, museum exhibitions, multimedia and hands-on reconstructions of historical experiments. We mix all these resources together to offer a historical route suitable to the various age groups. Creative analogical thinking, iconographic similarities and coincidences between the scientific and artistic domains are encouraged especially with children from 3 to 13 years old. These comparisons become pretexts for analysis, reflection and creative production also at the graphic level. In this paper we outline our methodology in the specific case of a laboratory and exhibition experience built around the person and work of Galileo. One of the results has been the involvement of the pupils in a new, unexpected emotional experience.     

Science Letters: Vascular architecture: is it a helpful histopathological biomarker for hepatocellular carcinoma?

Hepatocellular carcinoma (HCC) remains one of the major public health problems throughout the world. Although originally associated with tumorigenic processes, liver angiogenesis has also been observed in the context of different liver inflammatory, fibrotic, and ischemic conditions. Here we investigate the fractal dimension as a quantitator of non-Euclidean two-dimensional vascular geometry in a series of paired specimens of primary HCC and surrounding non-tumoral tissue, and discuss why this parameter might provide additional information regarding cancer behavior. The application of fractal geometry to the measurement of liver vascularity and the availability of a computer-aided quantitative method can eliminate errors in visual interpretation, and make it possible to obtain closer-to-reality numerals that are compulsory for any measurement process.     

Is there a real diagnostic impact of elastosonography and contrast-enhanced ultrasonography in the management of thyroid nodules?

Ultrasonography(US) and the new applications US elastography(USE) and contrast-enhanced US(CEUS) are used in the screening of thyroid nodules,for which fine-needle aspiration biopsy(FNAB) is the best single diagnostic test.The aim of the study was to compare the sensitivity,specificity,positive predictive value(PPV),and accuracy of the four examinations in nodules with cytological and histological diagnoses.The study used data from US,FNAB,USE(elasticity(ELX 2/1) index),and CEUS(Peak index and time to peak(TTP) index) evaluated in 73 thyroid nodules in 63 consecutive patients likely to undergo surgery.Cytological-histological correlation was available for 38 nodules.No correlation emerged between nodule size and cytological results.A significant(P=0.03) positive correlation between cumulative US findings and cytological results was found.In addition,significant correlations between cumulative US findings and cytology(P=0.02) and between cumulative US findings and histology(P<0.0001) were found.US showed the best specificity and PPV,and FNAB the best sensitivity.There was no significant difference in the ELX 2/1 index,Peak index,or TTP index among nodules subdivided according to cytological scores.No significant correlation was found between ELX 2/1 index,Peak index,and TTP index,on the one hand,and nodule size,US cumulative findings,cytology,and histology on the other hand.The sensitivity of the ELX 2/1 index was high,but its specificity was very low.The accuracy and PPV of USE were lower than those of the other procedures.Only the correlation between Peak index and cumulative US findings reached a value close to significance.Our ultimate aim is to minimise unnecessary thyroidectomy.US and FNAB continue to play a central diagnostic role.The use of a US score showed high specificity and PPV.The specificity of FNAB was low in this selected series because of the numbers of indeterminate cytological responses.USE and CEUS are innovative techniques that need to be standardized.The ELX 2/1 index,Peak index,and TTP index seem to be unrelated to histology.The best statistical data on USE and CEUS concerned their sensitivity and PPV,respectively.At present,USE and CEUS are too time-consuming and of limited utility in selecting patients for surgery.