Groups are not always the same

The idea of supporting group meetings at the same time and at the same place by computer raises the problem of how salient features of group behaviors are understood in meetings. In this paper we take a critical look at several beliefs about group behaviors in research dealing with electronic meeting systems (EMS). The paper argues based on an empirical study that the concept of a small, cohesive business team, so widely held, in all EMS research is not necessarily a valid starting point in thinking of meeting support. In particular, the paper critically evaluates a number of beliefs of user aspects, group features such as composition, structure and protocols, and task characteristics such as nature, importance and meeting goals. In consequence, if these prominent features can vary markedly all meeting support cannot be designed in ways envisaged in current research. In conclusion we outline some research questions—both of empirical and constructive nature—that need to be addressed if the EMS research wants to address issues in computer support in groups that are not similar with business teams.An earlier version of this paper was presented at 25th HICSS conference, 10–12.1.1993.This research was in part funded by the Academy of Finland.The opinions presented in this work are not official statements of any of the participating organizations.This research was in part funded by the Finnish Technology Development Center     

A time-to-amplitude converter with constant fraction timing discriminators for short time interval measurements

The construction and the performance of a time-to-amplitude converter equipped with constant fraction discriminators is described. The TAC consists of digital and analog parts which are constructed on two printed circuit boards, both of which are located in a single width NIM module. The dead time of the TAC for a start pulse which is not followed by a stop pulse within the time range of the device (～ 100 ns) is only ～ 100 ns, which enables one to avoid counting rate saturation even with a high random input signal rate.The differential and integral nonlinearities of the TAC are better than ± 1.5% and 0.0.5%, respectively. The resolution for input timing pulses of constant shape is 20 ps (fwhm), and less than 10 ps (fwhm) with a modification in the digital part. The walk error of the constant fraction timing discriminators is presented and various parameters affecting it are discussed. The effect of the various disturbances in linearity caused by the fast ECL logic and their minimization are also discussed.The time-to-amplitude converter has been used in positron lifetime studies and for laser range finding.     

Meta-searches in peer-to-peer networks

We propose a method for carrying out enhanced collaborative searches, called meta-searches, in peer-to-peer networks. In addition to performing regular searches, our method supports searches based on other network users’ previous searches on the same or similar topic. In essence, when a user performs a search, s/he will receive not only the usual result set, but also information on other users’ previous results, as well as relevancy information (such as how many times a resource that appeared in the result set was successfully downloaded). The core components of meta-search are query relevancy calculation, query matching algorithms, and relevancy file format. In this paper we discuss the underlying concepts and principles, and describe the component design in detail. Meta-search provides a way of benefiting from other users’ successful searches without any additional effort, thus potentially improving the efficiency and experience of a search.     

Advancing viewpoint merging in requirements engineering: a theoretical replication and explanatory study

Compared to building a single requirements view, modeling stakeholder viewpoints and then merging them is shown to improve the understanding of the problem domain, but also very time-consuming. How has the situation changed? This paper reports our replication of a case study, where we take advantage of theoretical replication to mitigate one of the original study design’s threats and to embrace an important evolving factor, namely automated tool support for producing \(i*\) models. Our replicate study updates the prior results by showing the time saving enabled by the tool and verifies the rich domain understanding gained through viewpoint-based modeling. In an attempt to explain why viewpoints lead to richer domain understanding, we examine in a posteriori way the role that traceability plays in building individual and team-wide requirements models. Our post hoc analysis results suggest that better traceability from the sources makes team-level requirements modeling more focused, whereas the lack of traceability makes it less fruitful. Our work not only shifts the case study from an exploratory to an explanatory nature, but also proposes the integration of conflict-centric views into viewpoint merging to further improve the understanding about stakeholder requirements’ trade-offs.     

Three-level frame and RD-schematic algorithm for automatic detection of individual trees from MLS point clouds

This article presents a three-level frame and a novel algorithm, which is based on a searching schematic analogous to a revolving door (RD), for automatic detection of individual trees from the point clouds acquired by mobile laser scanning (MLS). As a state-of-the-art technology, MLS in collecting the structural information of single trees is different from airborne laser scanners and terrestrial laser scanners in terms of sampling density, view angle and flexibility. To improve the efficiency and accuracy during extraction of trees, the three-level frame and the RD-schematic algorithm are proposed to fully employ the morphological characteristics of canopy surface models from coarse to fine resolutions. Methods of radius thresholding and symmetry judgement are also combined to remove disturbing objects, for example buildings and poles. Experiments based on the real-surveyed point clouds measured by the Sensei MLS system basically validate the proposed work, and the attributions introduced in this article serve as the fundamental procedures for further tree-relevant applications in regard to MLS.     

Automatic extraction of parallel edges based on eigenvalue analysis and collateral expansion

In the research field of remote sensing (RS), automatic extraction of parallel edges (AEPE) usually serves as the kernel when implementing automatic recognition of strip-like objects, such as rivers, highways, canyons and canals. The traditional algorithms proposed for edge detection commonly assume the mathematical singularity of boundaries as their theoretical basis and are also required to be all-prevalent, but the associated results cannot deal with the desired collection of parallel-only edges in most specific applications of RS data. To solve this problem, this article advances a novel algorithm for AEPE, which proceeds with the output edges from the existing edge-extraction methods as targets. The new algorithm comprises the procedure of eigenvalue analysis with improvements for extracting line segments, the procedure of collateral expansion for removing the non-parallel line segments recursively, and finally the procedure of segment connection. Finally, experiments based on both RS panchromatic images and light detection and ranging (LiDAR)-rastered images validate the new AEPE algorithm, with an efficacy greater than 70% and an accuracy better than 90%.     

Common pesticide increases costs of antipredator defenses in Rana temporaria tadpoles

Pesticides represent an important threat for natural populations. While their effects are assessed on short terms acute exposure, some of their harmful consequences may only become apparent when combined with other stressors, notably natural ones, such as predation. Here, we investigated in a laboratory experiment how exposure to a common fungicide (fenpropimorph) would affect the responses to predation in the common frog Rana temporaria. The concentrations of fungicide we used were comparable to those found in nature (0, 2, or 11 microg/L). The higher concentration of fungicide reduced tadpole activity late in the experiment, and only 7% of the tadpoles reached metamorphosis. In the lower concentration, the ability to respond adaptively to predator presence was not affected, but the costs (delayed metamorphosis, smaller relative body size) of this response were increased. Our results highlightthe need to investigate sublethal effects of pesticides on organismal performance if assessment of pesticides real impact is to be obtained.     

Cluster formation mechanisms of titanium dioxide during combustion synthesis: Observation with an APi-TOF

Few studies reported the formation of Ti-containing clusters in the initial stages of TiO₂ flame synthesis. The conversion from synthesis precursor to TiO₂ monomers was commonly assumed to take place through global reaction such as thermal decomposition and/or hydrolysis at high temperatures. More recent studies have been able to identify stable intermediates of Ti-containing monomers, most commonly Ti(OH)₄, as the final step before the formation of TiO₂. However, no larger Ti-containing cluster formation mechanisms or interactions between these monomers have been tracked. To investigate cluster formation pathways of TiO₂ during flame synthesis, Charged clusters were measured in an atmospheric pressure interface time-of-flight (APi-TOF) mass spectrometer. TiO₂ nanoparticles were synthesized by adding titanium tetraisopropoxide (TTIP) precursor to a premixed CH₄/O₂/N₂ flat flame aerosol reactor. Pure TiO₂ clusters were not detected by the APi-TOF. Results from measured mass spectra and mass defect plots show that for positively charged clusters, the abstraction of CH₂ groups occurs simultaneously with the clustering of larger intermediate organometallic species. For negatively charged clusters, NO_x formation pathways in the flame may play a role during the initial stages of TiO₂ formation, since a lot of Ti-containing clusters were attached with nitrate-related species. These research findings provide insights on quantum dot synthesis and molecular doping where rapid dilution of the flame synthesized nanoparticles is needed to better control the particle size and chemical composition. The possible influences of and potential artifacts brought by the dilution system on observing the incipient particle formation in flames were also discussed.

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