The Timbre Perception Test (TPT): A new interactive musical assessment tool to measure timbre perception ability

To date, tests that measure individual differences in the ability to perceive musical timbre are scarce in the published literature.The lack of such tool limits research on how timbre, a primary attribute of sound, is perceived and processed among individuals.The current paper describes the development of the Timbre Perception Test (TPT), in which participants use a slider to reproduce heard auditory stimuli that vary along three important dimensions of timbre: envelope, spectral flux, and spectral centroid. With a sample of 95 participants, the TPT was calibrated and validated against measures of related abilities and examined for its reliability. The results indicate that a short-version (8 minutes) of the TPT has good explanatory support from a factor analysis model, acceptable internal reliability (α=.69,ωt = .70), good test–retest reliability (r= .79) and substantial correlations with self-reported general musical sophistication (ρ= .63) and pitch discrimination (ρ= .56), as well as somewhat lower correlations with duration discrimination (ρ= .27), and musical instrument discrimination abilities (ρ= .33). Overall, the TPT represents a robust tool to measure an individual’s timbre perception ability. Furthermore, the use of sliders to perform a reproductive task has shown to be an effective approach in threshold testing. The current version of the TPT is openly available for research purposes

Minimizing node churn in peer-to-peer streaming

Several peer-to-peer (P2P) streaming systems have proved by now their ability to deliver live video streams to hundreds of users. However the inherent instability of the distribution environment poses several obstacles for these systems to manage to deliver a high quality experience to the end users. In this paper we explore node churn which independently of the distribution topology adopted, is an "anomaly" to the operation of the system leading to the degradation of playout quality. We argue that node churn is service specific and that churn in a P2P streaming service is highly correlated to the quality experienced at each node. On this basis we contribute a novel churn model to capture this twofold relationship and reveal unknown till now interactions while operating popular peer selection strategies under node churn. We provide evidence that selection strategies aiming solely at either efficiency or stability of a connection, although efficient for other P2P services such as P2P file sharing, lead to the formation of distribution topologies that are highly sensitive to node churn resulting in degraded performance. We propose a peer selection strategy designed to be P2P streaming service specific that takes decisions in short time scales while balances several factors such as connection efficiency, connection stability and content availability. It is proved that this approach achieves a uniform development of the distribution topology and leads to superior performance in terms of both low node churn and increased experienced quality. © 2010 Elsevier B.V. All rights reserved

On the impact of playout scheduling on the performance of peer-to-peer live streaming

In this paper we examine the impact of the adopted playout policy on the performance of P2P live streaming systems. We argue and demonstrate experimentally that (popular) playout policies which permit the divergence of the playout points of different nodes can deteriorate drastically the performance of P2P live streaming. Consequently, we argue in favor of keeping different playout points "near-in-time", even if this requires sacrificing (dropping) some late frames that could otherwise be rendered (assuming no strict bidirectional interactivity requirements are in place). Such nearly synchronized playout policies create "positive correlation" with respect to the available frames at different playout buffers. Therefore, they increase the number of upstream relay nodes from which a node can pull frames and thus boost the playout quality of both single-parent (tree) and multiple-parent (mesh) systems. On the contrary, diverging playout points reduce the number of upstream parents that can offer a gapless relay of the stream. This is clearly undesirable and should be avoided as it contradicts the fundamental philosophy of P2P systems which is to supplement an original service point with as many additional ones presented by the very own users of the service. © 2008 Elsevier B.V. All rights reserved

Determination of a variety of chemical classes of pesticides in surface and ground waters by off-line solid-phase extraction, gas chromatography with electron-capture and nitrogen-phosphorus detection, and high-performance liquid chromatography with post-column derivatization and fluorescence detection

Octadecyl (C18)-bonded porous silica was evaluated for the extraction of triazines, organochlorine, carbamates and acidic pesticides from surface and ground water. Gas chromatography with selected detection methods (electron-capture detection, nitrogen-phosphorus detection, mass spectrometry) and liquid chromatography-post-column derivatization fluorescence detection was employed for the determination of 32 pesticides. Recoveries varied from 52 to 102%. The recoveries of triazines obtained using C18 extraction cartridges and conventional liquid-liquid extraction (LLE) are compared. The limit of detection for seventeen organochlorine compounds was better than 0.003 μg/l and the limit of detection for other 15 analytes was better than 0.06 μg/l. The proposed analytical methodology was applied to analyze pesticides in surface and ground-water samples of the Lassithi Plateau, Crete, Greece. Copyright (C) 1998 Elsevier Science B.V

Spatial diversity of Cr distribution in soil and groundwater sites in relation with land use management in a Mediterranean region: The case of C. Evia and Assopos-Thiva Basins, Greece

The present study compiles new and literature data in a GIS platform aiming to (a) evaluate the extent and magnitude of Cr contamination in a Mediterranean region (Assopos-Thiva and Central Evia (Euboea) Basins, Greece); (b) combine spatial distribution of Cr in soil and groundwater with land use maps; (c) determine geochemical constraints on contamination by Cr; and (d) provide information that will be useful for better management of land use in a Mediterranean type ecosystem in order to prevent further degradation of natural resources. The spatial diversity of Cr distribution in soils and groundwater throughout the C. Evia and Assopos-Thiva Basins is considered. It is attributed to both natural Cr sources (Cr-bearing peridotites, affecting primarily soil) and human (industrial) activities (the dominant source of groundwater contamination). A combination of the spatial distribution of metals in soil and land use maps was used to define the specific areas of agricultural land use with elevated heavy metal contents. Furthermore, the combination of the spatial distribution of Cr in groundwater and land use maps allows for definition of specific areas of industrial land use with elevated Cr concentrations (Inofita, south Assopos-Thiva Basin). Despite the good correlation (r = 0.75) between Cr(VI) and the strong oxidant NO3 − in C. Evia, the lower standard potential (E0) values for NO3 − compared to those for Cr2O7 2− (the latter is a stronger oxidant than the former) suggest that NO3 − is not an oxidant of Cr. This detailed assessment and presentation of the available analytical data for soil and groundwater in Assopos-Thiva and C. Evia Basins on a land use map provides information for land management decision makers. © 2018 Elsevier B.V

Shoreline displacement and Pineios River diversions in NW Peloponnese (Greece) as result of the geology, active tectonics and human activity during the last 100 ky

Pineios River is the 3rd longest river in Peloponnese and flows in Kyllini wider area which is located close to the Hellenic Arc-Trench system. This is one of the most seismically and tectonically active regions in Greece with a great number of changes in the morphogenetic events taking place during the neotectonic period, as well as the last 100 ky. Prior to the 18th century A.D., the lower alluvial Pineios River flowed north of the Kyllini peninsula and into the Ionian Sea southwest of Kotichi Lagoon, but the river now flows southward into a deltaic swamp and dune region, burying a former lagoon-barrier coastal zone. From this, it becomes apparent that this river is not monotonous in appearance and therefore is not completely controlled by hydrology and hydraulics. In fact, the lower alluvial Pineios River has reacted to major geological controls, surface deformation and uplift movements caused by the activity of the recently mapped Pineios normal fault zone and salt tectonics in Kyllini peninsula resulting in the river flow diversion from north to south at completely different open sea areas. The effects of the geological, tectonic and neotectonic activity and the impact of the human presence and influence on the lower Pineios River are presented in this paper in order to determine the causes of the diversion of the lower (alluvial) Pineios River (NW Peloponnese, Greece) and shoreline displacements. © 2013 Gebrüder Borntraeger Verlagsbuchhandlung

Assessment of continuous sky view factor based on ultra-high resolution natural colour images acquired by remotely piloted airborne systems for applications in an urban area of athens

The thermal comfort conditions in a complex urban area is influenced by the surrounding structures and obstacles which modify the incoming radiation fluxes. A measure of this modification is the sky view factor (SVF), which could be estimated in each point of a selected area if a high resolution digital elevation model (DEM), or other urban morphological data including the manmade infrastructure, are available. The goal of this study is to model the continuous SVF for a complex building environment in the campus of National and Kapodistrian University of Athens, based on a high resolution DEM (0.09 m). For this purpose, we applied the structure-from-motion (SfM) technique, which takes advantage of the interpretation of ultra-high resolution colour images acquired by remotely piloted airborne systems, also known as drones or unmanned aerial vehicles. A quantitative analysis, by applying statistical metrics, yields perfect agreement between modelled and observed SVF values, over the examined area. The proposed methodology could be applied for human-biometeorology research in micro scale complex urban environments. © 2017 Informa UK Limited, trading as Taylor & Francis Group

Automated coastline extraction using the very high resolution worldview (WV) satellite imagery and developed coastline extraction tool (CET)

The accurate extraction of a coastline is necessary for various studies of coastal processes, as well as for the management and protection of coastal areas. Very high-resolution satellite imagery has great potential for coastline extraction; however, noises in spectral data can cause significant errors. Here, we present a newly developed Coastal Extraction Tool (CET) that overcomes such errors and allows accurate and time-efficient automated coastline extraction based on a combination of WorldView-2 (WV-2) multispectral imagery and stereo-pair-derived digital surface model (DSM). Coastline extraction is performed and tested on the Iž-Rava island group, situated within the Northern Dalmatian archipelago (Croatia). Extracted coastlines were compared to (a) coastlines extracted from state topographic map (1:25,000), and (b) coastline extracted by another available tool. The accuracy of the extracted coastline was validated with centimeter accuracy reference data acquired using a UAV system (Matrice 600 Pro + MicaSense RedEdge-MX). Within the study area, two small islets were detected that have not been mapped during the earlier coastline mapping efforts. CET proved to be a highly accurate coastline mapping technique that successfully overcomes spectral-induced errors. In future research, we are planning to integrate data obtained by UAVs infrared thermography (IRT) and in situ sensors, measuring sea and land surface temperatures (SST and LST), into the CET, given that this has shown promising results. Considering its accuracy and ease of use, we suggest that CET can be applied for automated coastline extraction in other large and indented coastal areas. Additionally, we suggest that CET could be applied in longitudinal geomorphological coastal erosion studies for the automated detection of spatio-temporal coastline displacement. © 2021 by the authors. Licensee MDPI, Basel, Switzerland