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Long-term Measurements (long-term + measurement)
Selected AbstractsROCK-SURFACE TEMPERATURES OF BASALT IN THE DRAKENSBERG ALPINE ENVIRONMENT, LESOTHOGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 3 2007STEFAN GRAB ABSTRACT. Rock temperature data are presented for a variety of topographic localities at a high Drakensberg site. The objective is to investigate the spatiotemporal variations of surface rock temperatures in high Drakensberg basalt. The temperature results are then used to discuss possible implications for thermal stress fatigue and frost-induced weathering. TinytalkÔ data loggers and probes were used for rock-surface temperature recording. Long-term measurements were recorded over 12 months from May 2002 to April 2003, at a 1-hour logging interval and rock depth of 1 cm for a highaltitude (3300 m a.s.l.) interfluve and fracture site. Whilst the north-facing rock surface experiences negligible hours below ,3°C, the south-facing rock surface and interfluve sites are subjected to considerable periods below ,3°C, which falls within the ,frost cracking window'. It is concluded that the substantial contrasts of recorded rock thermal parameters over small spatial scales between various topographic settings, highlight that site-specific measurements across the broader scale are required for an adequate evaluation of regional weathering and its associated landform development. [source] Evaluation of 08CH18N10T stainless steel corrosion in subcritical water by electrochemical noise analysisMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 9 2008P. Ku Abstract The corrosion behaviour of pressurized water reactor (PWR) steam generator tube material (08CH18N10T steel) was studied by electrochemical noise (EN) measurements and electrochemical impedance spectroscopy in high-temperature water at 280,°C and 8 MPa. Long-term measurements were performed in two electrolytes: (i) deionised water alkalized to pH25,=,9.5 by KOH; (ii) the same electrolyte with 200 ppm of chlorides added (as KCl). The noise data were processed by two filtering methods and the noise resistance and spectral noise resistance values were calculated. Different contributions to the total impedance were identified and the polarization resistance values were calculated from EIS data. Noise and polarization resistances were compared and the influence of filtering methods was discussed. Instantaneous corrosion data were transformed to integral ones and comparison with mean corrosion current estimated from the oxide thickness was made. It was confirmed that the crucial point of EN analysis is selection of proper cut-off frequency in high-pass fast Fourier transform (HP-FFT). [source] Automated diffusion chambers to monitor diurnal and seasonal dynamics of the soil CO2 concentration profileEUROPEAN JOURNAL OF SOIL SCIENCE, Issue 4 2009F. Albanito Summary To better understand the factors controlling carbon dioxide (CO2) production and transport in soil, we developed a new method to continuously monitor soil CO2 concentration at multiple depths, by using diffusion chambers. The soil diffusion chambers are constructed from a high-density polyethylene cylindrical frame enclosed by a micro-polyvinylidene difluoride flat membrane (PVDF). All chambers are linked to an infrared gas analyser positioned above-ground through a multi-port valve system. We set up two experimental sites for long-term measurements of soil CO2 concentration, soil temperature and soil water content at depths of 0, 10, 20, 40 and 80 cm. The system provides the following advantages : (i) the use of the PVDF combined with the small dimensions of the diffusion chambers allows rapid diffusion of soil gas into the chambers and therefore a short equilibration time of the gas phase with the surrounding soil atmosphere, (ii) the equilibrating closed loop system allows the semi-continuous measurement of soil profile CO2 concentrations without creating a pressure differential within the chambers, thus reducing gas concentration distortions in the soil, (iii) the small size of the closed diffusion chambers reduces the initial soil disturbance during installation, (iv) it allows sampling in wet, humid soils, including ones that are waterlogged or temporarily saturated, and (v) the chambers do not require removal for maintenance purposes and are inexpensive. [source] Neural Signal Manager: a collection of classical and innovative tools for multi-channel spike train analysisINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 11 2009Antonio Novellino Abstract Recent developments in the neuroengineering field and the widespread use of the micro electrode arrays (MEAs) for electrophysiological investigations made available new approaches for studying the dynamics of dissociated neuronal networks as well as acute/organotypic slices maintained ex vivo. Importantly, the extraction of relevant parameters from these neural populations is likely to involve long-term measurements, lasting from a few hours to entire days. The processing of huge amounts of electrophysiological data, in terms of computational time and automation of the procedures, is actually one of the major bottlenecks for both in vivo and in vitro recordings. In this paper we present a collection of algorithms implemented within a new software package, named the Neural Signal Manager (NSM), aimed at analyzing a huge quantity of data recorded by means of MEAs in a fast and efficient way. The NSM offers different approaches for both spike and burst analysis, and integrates state-of-the-art statistical algorithms, such as the inter-spike interval histogram or the post stimulus time histogram, with some recent ones, such as the burst detection and its related statistics. In order to show the potentialities of the software, the application of the developed algorithms to a set of spontaneous activity recordings from dissociated cultures at different ages is presented in the Results section. Copyright © 2008 John Wiley & Sons, Ltd. [source] A controlled study of the short- and long-term effects of a Train the Trainers courseMEDICAL EDUCATION, Issue 7 2008Sune Rubak Objectives, This study aimed to establish the longterm effects of a 3-day ,Training for Trainers' course (TTC) on doctors' knowledge, teaching behaviour and clinical learning climate. Methods, The study was designed as an intervention study with pre-, post- and long-term measurements. The intervention group (I-group) included 118 doctors from the departments of internal medicine and orthopaedic surgery at one university hospital. The control group (C-group) consisted of 125 doctors from the corresponding departments at another university hospital. Gains in knowledge about teaching skills were assessed by a written test. Teaching behaviour and learning climate were evaluated by questionnaires. Results, In the I-group, 98.4% of doctors, both specialists and trainees, participated in a TTC. Response rates on the written test varied from 90% at baseline to 70% at 6 months after the intervention. Knowledge about teaching skills increased in the I-group by 25% after the TTC and was sustained at 6 months. Questionnaire response rates varied from 98.4% at baseline to 84.8% at 6 months. Post-course, the teaching behaviour of the I-group significantly changed and its learning climate improved compared with the C-group. Scores for use of feedback and supervision in the I-group increased from 4,5 to 6,7 (maximum score = 9). This was significantly higher than in the C-group. Conclusions, A 3-day residential TTC has a significant impact in terms of gains of knowledge concerning teaching skills, teaching behaviour and learning climate after 6 months. The positive effects demonstrated in this study were rooted in both the specialists and trainees who attended the course. [source] Experimentally testing the role of foundation species in forests: the Harvard Forest Hemlock Removal ExperimentMETHODS IN ECOLOGY AND EVOLUTION, Issue 2 2010Aaron M. Ellison Summary 1.,Problem statement, Foundation species define and structure ecological systems. In forests around the world, foundation tree species are declining due to overexploitation, pests and pathogens. Eastern hemlock (Tsuga canadensis), a foundation tree species in eastern North America, is threatened by an exotic insect, the hemlock woolly adelgid (Adelges tsugae). The loss of hemlock is hypothesized to result in dramatic changes in assemblages of associated species with cascading impacts on food webs and fluxes of energy and nutrients. We describe the setting, design and analytical framework of the Harvard Forest Hemlock Removal Experiment (HF-HeRE), a multi-hectare, long-term experiment that overcomes many of the major logistical and analytical challenges of studying system-wide consequences of foundation species loss. 2.,Study design, HF-HeRE is a replicated and blocked Before-After-Control-Impact experiment that includes two hemlock removal treatments: girdling all hemlocks to simulate death by adelgid and logging all hemlocks >20 cm diameter and other merchantable trees to simulate pre-emptive salvage operations. These treatments are paired with two control treatments: hemlock controls that are beginning to be infested in 2010 by the adelgid and hardwood controls that represent future conditions of most hemlock stands in eastern North America. 3.,Ongoing measurements and monitoring, Ongoing long-term measurements to quantify the magnitude and direction of forest ecosystem change as hemlock declines include: air and soil temperature, light availability, leaf area and canopy closure; changes in species composition and abundance of the soil seed-bank, understorey vegetation, and soil-dwelling invertebrates; dynamics of coarse woody debris; soil nitrogen availability and net nitrogen mineralization; and soil carbon flux. Short-term or one-time-only measurements include initial tree ages, hemlock-decomposing fungi, wood-boring beetles and throughfall chemistry. Additional within-plot, replicated experiments include effects of ants and litter-dwelling microarthoropods on ecosystem functioning, and responses of salamanders to canopy change. 4.,Future directions and collaborations, HF-HeRE is part of an evolving network of retrospective studies, natural experiments, large manipulations and modelling efforts focused on identifying and understanding the role of single foundation species on ecological processes and dynamics. We invite colleagues from around the world who are interested in exploring complementary questions to take advantage of the HF-HeRE research infrastructure. [source] A new method for estimating insolation based on PV-module currents in a cluster of stand-alone solar systemsPROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 5 2007Frans Nieuwenhout Abstract In order to evaluate the performance of solar home systems (SHSs), data on local insolation is a prerequisite. We present a new method to estimate insolation if direct measurements are unavailable. This method comprises estimation of daily irradiation by correlating photovoltaic (PV) module currents from a number of SHSs, located a few kilometres apart. The method was tested with a 3-year time series for nine SHS in a remote area in Indonesia. Verification with reference cell measurements over a 2-month period showed that our method could determine average daily irradiation with a mean bias error of 1·3%. Daily irradiation figures showed a standard error of 5%. The systematic error in this method is estimated to be around 10%. Especially if calibration with measurements during a short period is possible, the proposed method provides more accurate monthly insolation figures compared with the readily available satellite data from the NASA SSE database. An advantage of the proposed method over satellite data is that irradiation figures can be calculated on a daily basis, while the SSE database only provides monthly averages. It is concluded that the new method is a valuable tool to obtain information on insolation when long-term measurements are absent. Copyright © 2007 John Wiley & Sons, Ltd. [source] Intra- and Interannual Vegetation Change: Implications for Long-Term ResearchRESTORATION ECOLOGY, Issue 1 2008Julie E. Korb Abstract To draw reliable conclusions from forest restoration experiments, it is important that long-term measurements be repeatable or year-to-year variability may interfere with the correct interpretation of treatment effects. We used permanent plots in a long-term restoration study in southwestern Colorado to measure herbaceous and shrub vegetation at three dates within a single year (June, July, and August), and between years (2003 and 2005), on untreated control plots in a warm, dry mixed conifer forest. Growing season precipitation patterns were similar between 2003 and 2005, so differences in vegetation should be related primarily to differences in the sampling month. Significant indicator species for each sampling month were present within a single year (2005), primarily reflecting early-season annuals. We found no significant differences for total species abundance (2005). Species richness, abundance, and indicator species were significantly different between years for different sampling months indicating that sampling should be conducted within a similar time frame to avoid detecting differences that are not due to treatment effects or variations in year-to-year climate. These findings have implications for long-term research studies where the objectives are to detect changes over time in response to treatments, climate variation, and natural processes. Long-term sampling should occur within a similar phenological time frame each year over a short amount of time and should be based on the following criteria: (1) the sampling period is congruent with research objectives such as detecting rare species or peak understory abundance and (2) the sampling period is feasible in regard to personnel and financial constraints. [source] | |||||||||||||