Optimal implementations of UPGMA and other common clustering algorithms

In this work we consider hierarchical clustering algorithms, such as UPGMA, which follow the closest-pair joining scheme. We survey optimal O(n²)-time implementations of such algorithms which use a ‘locally closest’ joining scheme, and specify conditions under which this relaxed joining scheme is equivalent to the original one (i.e. ‘globally closest’).     

On the temporal relations between memory scanning and response preparation

Three experiments were conducted to investigate whether response processes can start before memory scanning has finished when both are required in the same task. In Experiment 1 the color of a stimulus letter determined which hand might respond, and the letter's memory set membership determined whether that response should be made or withheld. Electrophysiological data suggested that lateralized response preparation was not initiated until memory scanning finished. Experiment 2 replicated these results with a consistent stimulus-response mapping to make the scanning process easier. Experiment 3 tested for earlier response priming with a probe reaction time paradigm, and the results suggested that color information can be used to activate a response before memory scanning is finished. The results of Experiments 1-3 suggest that interference between memory scanning and response preparation precludes the concurrent operation of these processes.     

3D Shape Recovery of Smooth Surfaces: Dropping the Fixed-Viewpoint Assumption

We present a new method for recovering the 3D shape of a featureless smooth surface from three or more calibrated images illuminated by different light sources (three of them are independent). This method is unique in its ability to handle images taken from unconstrained perspective viewpoints and unconstrained illumination directions. The correspondence between such images is hard to compute and no other known method can handle this problem locally from a small number of images. Our method combines geometric and photometric information in order to recover dense correspondence between the images and accurately computes the 3D shape. Only a single pass starting at one point and local computation are used. This is in contrast to methods that use the occluding contours recovered from many images to initialize and constrain an optimization process. The output of our method can be used to initialize such processes. In the special case of fixed viewpoint, the proposed method becomes a new perspective photometric stereo algorithm. Nevertheless, the introduction of the multiview setup, self-occlusions, and regions close to the occluding boundaries are better handled, and the method is more robust to noise than photometric stereo. Experimental results are presented for simulated and real images.     

Knowledge transfer in globally distributed teams: the role of transactive memory

This paper explores the role of transactive memory in enabling knowledge transfer between globally distributed teams. While the information systems literature has recently acknowledged the role transactive memory plays in improving knowledge processes and performance in colocated teams, little is known about its contribution to distributed teams. To contribute to filling this gap, knowledge‐transfer challenges and processes between onsite and offshore teams were studied at TATA Consultancy Services. In particular, the paper describes the transfer of knowledge between onsite and offshore teams through encoding, storing and retrieving processes. An in‐depth case study of globally distributed software development projects was carried out, and a qualitative, interpretive approach was adopted. The analysis of the case suggests that in order to overcome differences derived from the local contexts of the onsite and offshore teams (e.g. different work routines, methodologies and skills), some specific mechanisms supporting the development of codified and personalized ‘directories’ were introduced. These include the standardization of templates and methodologies across the remote sites as well as frequent teleconferencing sessions and occasional short visits. These mechanisms contributed to the development of the notion of ‘who knows what’ across onsite and offshore teams despite the challenges associated with globally distributed teams, and supported the transfer of knowledge between onsite and offshore teams. The paper concludes by offering theoretical and practical implications.     

Lower bounds for testing Euclidean Minimum Spanning Trees

The Euclidean Minimum Spanning Tree problem is to decide whether a given graph G=(P,E) on a set of points in the two-dimensional plane is a minimum spanning tree with respect to the Euclidean distance. Czumaj et al. [A. Czumaj, C. Sohler, M. Ziegler, Testing Euclidean Minimum Spanning Trees in the plane, Unpublished, Part II of ESA 2000 paper, downloaded from http://web.njit.edu/~czumaj/] gave a 1-sided-error non-adaptive property-tester for this task of query complexity . We show that every non-adaptive (not necessarily 1-sided-error) property-tester for this task has a query complexity of , implying that the test in [A. Czumaj, C. Sohler, M. Ziegler, Testing Euclidean Minimum Spanning Trees in the plane, Unpublished, Part II of ESA 2000 paper, downloaded from http://web.njit.edu/~czumaj/] is of asymptotically optimal complexity. We further prove that every adaptive property-tester has query complexity of Ω(n1/3). Those lower bounds hold even when the input graph is promised to be a bounded degree tree.     

Sourcing in or out: Implications for social capital and knowledge sharing

The sharing of knowledge between a firm and its internal or external service suppliers has become an important element of contemporary sourcing arrangements. Moreover, the knowledge based view (KBV) has long suggested that due to stronger cognitive links within firms, internal compared to external service provision creates better conditions for knowledge sharing. Empirical evidence for this claim is however scarce, and the KBV does not explain the mechanisms for more knowledge sharing in internal sourcing in detail. Moreover, there is now some evidence to suggest that firms’ relationships with external sourcing partners are becoming more similar to those with captive centres, which represent a less traditional form of insourcing setting. To scrutinize the possible knowledge sharing advantages of internal sourcing in more depth, we turn to social capital (SC) research. There are some theoretical claims that SC and knowledge sharing are stronger within than between firms, and there is ample evidence that SC facilitates knowledge sharing. Our survey results suggest that the extent of knowledge sharing and SC are indeed stronger in a captive than in an external sourcing mode, and that structural (tie strength), cognitive (shared understanding), and relational (trust) aspects of SC mediate the effect of sourcing mode on the extent of knowledge sharing. By contrast, network stability (a structural aspect) mediated knowledge sharing only indirectly, by reinforcing the other SC aspects. We highlight important contributions to research and practice of IS outsourcing and social capital.     

Experimental and physical approaches on a novel semiconducting-ionic membrane fuel cell

Semiconducting-ionic membranes (SIMs) have exhibited significant superiority to replace the conventional ionic electrolytes in solid oxide fuel cells (SOFCs). One interesting phenomenon is that the SIMs can successfully avoid the underlying short-circuiting issue and power losses while bringing significantly enhanced power output. It is crucial to understand the physics in such devices as they show distinct electrochemical processes with conventional fuel cells. We first presented experimental studies of a SIM fuel cell based on a composite of semiconductor LiCo_0.8Fe_0.2O₂ (LCF) and ionic conductor Sm-doped CeO₂ (SDC), which achieved a remarkable power density of 1150 mW cm^?2 at 550 °C along with a high open circuit voltage (OCV) of 1.04 V. Then, for the first time we used a physical model via combining a semiconductor-ionic contact junction with a rectifying layer which blocks the electron leakage to describe such unique SIM device and excellent performance. Current and power are the most important characteristics for the device, by introducing the rectifying layer we described the SIM physical nature and new device process. This work presented a new view on advanced SIM SOFC science and technology from physics.