DYFRAM: dynamic fragmentation and replica management in distributed database systems

In distributed database systems, tables are frequently fragmented and replicated over a number of sites in order to reduce network communication costs. How to fragment, when to replicate and how to allocate the fragments to the sites are challenging problems that has previously been solved either by static fragmentation, replication and allocation, or based on a priori query analysis. Many emerging applications of distributed database systems generate very dynamic workloads with frequent changes in access patterns from different sites. In such contexts, continuous refragmentation and reallocation can significantly improve performance. In this paper we present DYFRAM, a decentralized approach for dynamic table fragmentation and allocation in distributed database systems based on observation of the access patterns of sites to tables. The approach performs fragmentation, replication, and reallocation based on recent access history, aiming at maximizing the number of local accesses compared to accesses from remote sites. We show through simulations and experiments on the DASCOSA distributed database system that the approach significantly reduces communication costs for typical access patterns, thus demonstrating the feasibility of our approach.     

A local construction of the Smith normal form of a matrix polynomial

We present an algorithm for computing a Smith form with multipliers of a regular matrix polynomial over a field. This algorithm differs from previous ones in that it computes a local Smith form for each irreducible factor in the determinant separately and then combines them into a global Smith form, whereas other algorithms apply a sequence of unimodular row and column operations to the original matrix. The performance of the algorithm in exact arithmetic is reported for several test cases.     

Forest biomass mapping from lidar and radar synergies

The use of lidar and radar instruments to measure forest structure attributes such as height and biomass at global scales is being considered for a future Earth Observation satellite mission, DESDynI (Deformation, Ecosystem Structure, and Dynamics of Ice). Large footprint lidar makes a direct measurement of the heights of scatterers in the illuminated footprint and can yield accurate information about the vertical profile of the canopy within lidar footprint samples. Synthetic Aperture Radar (SAR) is known to sense the canopy volume, especially at longer wavelengths and provides image data. Methods for biomass mapping by a combination of lidar sampling and radar mapping need to be developed.In this study, several issues in this respect were investigated using aircraft borne lidar and SAR data in Howland, Maine, USA. The stepwise regression selected the height indices rh50 and rh75 of the Laser Vegetation Imaging Sensor (LVIS) data for predicting field measured biomass with a R² of 0.71 and RMSE of 31.33 Mg/ha. The above-ground biomass map generated from this regression model was considered to represent the true biomass of the area and was used as a reference map since no better biomass map exists for the area. Random samples were taken from the biomass map and the correlation between the sampled biomass and co-located SAR signature was studied. The best models were used to extend the biomass from lidar samples into all forested areas in the study area, which mimics a procedure that could be used for the future DESDYnI mission. It was found that depending on the data types used (quad-pol or dual-pol) the SAR data can predict the lidar biomass samples with R² of 0.63-0.71, RMSE of 32.0-28.2 Mg/ha up to biomass levels of 200-250 Mg/ha. The mean biomass of the study area calculated from the biomass maps generated by lidar-SAR synergy was within 10% of the reference biomass map derived from LVIS data. The results from this study are preliminary, but do show the potential of the combined use of lidar samples and radar imagery for forest biomass mapping. Various issues regarding lidar/radar data synergies for biomass mapping are discussed in the paper.     

Virtual spectrophotometric measurements for biologically and physically based rendering

Published online: 18 September 2001     

Effects of α-Terthienyl on the midgut detoxification enzymes of the European corn borer,Ostrinia nubilalis

The biochemical basis for the tolerance of the European corn borer,Ostrinia nubilalis, to the phototoxin-terthienyl was investigated by measuring the midgut polysubstrate monooxygenases and glutathioneS-transferase activities.-Terthienyl administered in the diet to the corn borers increased the level of cytochromeb ₅, NADH-cytochromec reductase,O-demethylase, and glutathioneS-transferase activities. The induced detoxification enzyme activities should enable the corn borer to metabolize-terthienyl more efficiently and therefore render the corn borer highly tolerant to-terthienyl.     

Maintenance of Response Readiness in Patients With Parkinson's Disease: Evidence From a Simple Reaction Time Task.

The authors explored the effect of Parkinson's disease (PD) on the generation and maintenance of response readiness in a simple reaction time task. They compared performance of idiopathic PD patients without dementia, age-matched controls, and younger controls over short (1-, 3-, and 6-s) and long (12- and 18-s) foreperiod intervals. After each trial, the authors probed memory for visual information that also had to be maintained during the trial interval. Patients and controls did not differ overall in their ability to maintain readiness over long delays. However, within the PD group only, errors in maintaining visual information were correlated with difficulty in maintaining readiness, suggesting that systems impaired in PD may facilitate the maintenance of processing in both motor and cognitive domains. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Critique of Relational Psychoanalysis.

Psychoanalysis today is largely a psychology of consciousness: Post- and neo-Freudians form a marginalized community within North America in comparison to contemporary relational and intersubjective theorists, who emphasize the phenomenology of lived conscious experience, dyadic attachments, affective attunement, social construction, and mutual recognition over the role of insight and interpretation. Despite the rich historical terrain of theoretical variation and advance, many contemporary approaches have displaced the primacy of the unconscious. Notwithstanding the theoretical hairsplitting that historically occurs across the psychoanalytic domain, one is beginning to see with increasing force and clarity what S. Mitchell and L. Aron (1999) referred to as the emergence of a new tradition, namely, relational psychoanalysis. Having its edifice in early object relations theory, the British middle school and American interpersonal traditions, and self psychology, relationality is billed as "a distinctly new tradition" (Mitchell & Aron, 1999, p. x). What is being labeled as the American middle group of psychoanalysis (C. Spezzano, 1997), relational and intersubjective theory have taken center stage. It may be argued, however, that contemporary relational and intersubjective perspectives have failed to be properly critiqued from within their own school of discourse. The scope of this article is largely preoccupied with tracing (a) the philosophical underpinnings of contemporary relational theory, (b) its theoretical relation to traditional psychoanalytic thought, (c) clinical implications for therapeutic practice, and (d) its intersection with points of consilience that emerge from these traditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Functional Projection: How Fundamental Social Motives Can Bias Interpersonal Perception.

Results from 2 experimental studies suggest that self-protection and mate-search goals lead to the perception of functionally relevant emotional expressions in goal-relevant social targets. Activating a self-protection goal led participants to perceive greater anger in Black male faces (Study 1) and Arab faces (Study 2), both out-groups heuristically associated with physical threat. In Study 2, participants' level of implicit Arab-threat associations moderated this bias. Activating a mate-search goal led male, but not female, participants to perceive more sexual arousal in attractive opposite-sex targets (Study 1). Activating these goals did not influence perceptions of goal-irrelevant targets. Additionally, participants with chronic self-protective and mate-search goals exhibited similar biases. Findings are consistent with a functionalist, motivation-based account of interpersonal perception. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Health Service Use Predictors Among Trauma Survivors: A Critical Review.

This article had 2 aims: (a) to comprehensively review and synthesize the literature on predictors of health service utilization in survivors of traumatic events and posttraumatic stress disorder (PTSD) patients and (b) to discuss methodological issues in examining service utilization in this population. PsycINFO was searched for relevant articles published through April 2004. Included studies had to primarily sample trauma survivors or PTSD patients and statistically explore health service use determinants. Although some findings conflicted across studies, increased mental health service use was generally related to being female, having a previous trauma history, and having a PTSD diagnosis. Increased medical service use was found among those with a PTSD diagnosis. Methodological recommendations are made for future health service use studies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)