Sensitivity of Estimates of Seasonal Phytoplankton Photosynthesis to Sampling Frequency

1994 ◽  
Vol 51 (12) ◽  
pp. 2734-2738 ◽  
Author(s):  
E. U. Schindler ◽  
E. R. DeBruyn ◽  
E. J. Fee ◽  
J. A. Shearer
Keyword(s):  
Thermal Stratification ◽  
Sampling Frequency ◽  
Canadian Shield ◽  
Data Sets ◽  
Time Intervals ◽  
Rainfall Events ◽  
Northwestern Ontario ◽  
Regular Time ◽  
Sampling Intervals ◽  
Phytoplankton Photosynthesis

Phytoplankton photosynthesis was monitored once or twice weekly in an oligotrophic Canadian Shield lake in northwestern Ontario during the ice-free season for 6 yr. These data sets were subsampled in various ways to determine how the precision of estimates of ice-free season phytoplankton photosynthesis was affected by sampling frequency. Deviations were as large as 20% if a measurement was not taken before thermal stratification was established in the spring, or if samples were taken at monthly intervals during the ice-free season. Shorter sampling intervals (1, 2, and 3 wk were tested) all resulted in deviations of about 10%. Taking samples irregularly (every day for the 3 d subsequent to rainfall events ≥ 5 mm) instead of at regular time intervals did not reduce deviations.

scholarly journals Time-lapse monitoring of fluid-induced geophysical property variations within an unstable earthwork using P-wave refraction

Geophysics ◽  
2016 ◽  
Vol 81 (4) ◽  
pp. EN17-EN27 ◽  
Author(s):  
Paolo Bergamo ◽  
Ben Dashwood ◽  
Sebastian Uhlemann ◽  
Russell Swift ◽  
Jonathan E. Chambers ◽  
...  
Keyword(s):  
Time Lapse ◽  
P Wave ◽  
Data Sets ◽  
Time Intervals ◽  
Total Period ◽  
Seismic Properties ◽  
Wave Refraction ◽  
Regular Time ◽  
Spatial Locations ◽  
Spatial Regularization

A significant portion of the UK’s transportation system relies on a network of geotechnical earthworks (cuttings and embankments) that were constructed more than 100 years ago, whose stability is affected by the change in precipitation patterns experienced over the past few decades. The vulnerability of these structures requires a reliable, cost- and time-effective monitoring of their geomechanical condition. We have assessed the potential application of P-wave refraction for tracking the seasonal variations of seismic properties within an aged clay-filled railway embankment, located in southwest England. Seismic data were acquired repeatedly along the crest of the earthwork at regular time intervals, for a total period of 16 months. P-wave first-break times were picked from all available recorded traces, to obtain a set of hodocrones referenced to the same spatial locations, for various dates along the surveyed period of time. Traveltimes extracted from each acquisition were then compared to track the pattern of their temporal variability. The relevance of such variations over time was compared with the data experimental uncertainty. The multiple set of hodocrones was subsequently inverted using a tomographic approach, to retrieve a time-lapse model of [Formula: see text] for the embankment structure. To directly compare the reconstructed [Formula: see text] sections, identical initial models and spatial regularization were used for the inversion of all available data sets. A consistent temporal trend for P-wave traveltimes, and consequently for the reconstructed [Formula: see text] models, was identified. This pattern could be related to the seasonal distribution of precipitation and soil-water content measured on site.

Assessing the Validity of Near-Infrared Monochromator Calibrations over Time

1998 ◽  
Vol 52 (4) ◽  
pp. 604-612 ◽  
Author(s):  
Eric Bouveresse ◽  
Chiara Casolino ◽  
Désiré-Luc Massart
Keyword(s):  
Near Infrared ◽  
Calibration Model ◽  
Data Sets ◽  
Time Intervals ◽  
Regular Time ◽  
Calibration Models ◽  
Infrared Spectrometer ◽  
Near Infrared Spectrometer ◽  
Over Time ◽  
Infrared Data

A procedure to check the validity of near-infrared calibration models over time is proposed. Validation samples are analyzed at regular time intervals by both near-infrared and reference methods in order to check the validity of the near-infrared calibration model. When an invalid situation is detected, a stable polystyrene standard is measured, to determine whether this invalid situation is due to fluctuations of the instrumental response of the near-infrared spectrometer or not. A first method based on simulating simple instrumental differences enables one to correct those simple differences with only the polystyrene standard. It is shown that such an approach can correct most of the simple instrumental differences without the use of standardization procedures. However, when the invalid situation is due to more complex instrumental differences, standardization must be applied. This procedure is applied to simulated and real near-infrared data sets.

Development of a Low-Power, Low-Cost Remote Pipe Parameters Monitoring Device

2002 ◽  
Author(s):  
Paulo R. G. Kurka ◽  
Carlos Geraldo Quinholi ◽  
Eduardo Laurino ◽  
Guilherme V. P. Donato
Keyword(s):  
Low Power ◽  
Low Cost ◽  
Recording Device ◽  
Stress Monitoring ◽  
Recording Equipment ◽  
Time Intervals ◽  
Regular Time ◽  
Sample Data ◽  
Sampling Intervals ◽  
And Performance

The work presents the features and performance of a dedicated system for monitoring stresses in the vicinity of retention valves in a long oil pipe. Monitoring stations that can be numerous and located in remote regions, where no electric power is available, must be operated by batteries which provide a somewhat limited supply of energy. The project of a low-cost low-power consumption device is therefore of great importance for keeping records of strains, or any other engineering parameter that develop remotely on the pipe. The system developed is a simultaneous 5-channel analog data conditioning and recording equipment, that can be programmed to sample data at regular time intervals. The recording device can be any voice/music standard monaural cassette tape recorder. The paper displays project details as well as qualitative results of circumferential and longitudinal stress monitoring in a remote measuring station, with 4 data channels per station, recorded during 7 consecutive days at 15 minutes sampling intervals.

Land water linkages: influences of riparian deforestation on lake thermocline depth and possible consequences for cold stenotherms

1997 ◽  
Vol 54 (6) ◽  
pp. 1299-1305 ◽  
Author(s):  
Robert France
Keyword(s):  
Thermal Stratification ◽  
Lake Trout ◽  
Salvelinus Namaycush ◽  
Thermocline Depth ◽  
Experimental Lakes Area ◽  
Northwestern Ontario ◽  
Riparian Trees ◽  
Tree Removal ◽  
Riparian Tree ◽  
Land Water

The purpose of the present study was to determine if riparian deforestation would expose lake surfaces to stronger winds and therefore bring about deepening of thermoclines and resulting habitat losses for cold stenotherms such as lake trout (Salvelinus namaycush). Removal of protective riparian trees through wind blowdown and two wildfires was found to triple the overwater windspeeds and produce thermocline deepening in two lakes at the Experimental Lakes Area. A survey of thermal stratification patterns in 63 northwestern Ontario lakes showed that lakes around which riparian trees had been removed a decade before through either clearcutting or by a wildfire were found to have thermocline depths over 2 m deeper per unit fetch length compared with lakes surrounded by mature forests. Riparian tree removal will therefore exacerbate hypolimnion habitat losses for cold stenotherms that have already been documented to be occurring as a result of lake acidification, eutrophication, and climate warming.

scholarly journals Speech rhythm: a metaphor?

2014 ◽  
Vol 369 (1658) ◽  
pp. 20130396 ◽  
Author(s):  
Francis Nolan ◽  
Hae-Sung Jeon
Keyword(s):  
Traditional View ◽  
Time Intervals ◽  
Speech Rhythm ◽  
Linguistic Structure ◽  
Regular Time ◽  
Linguistic Functions ◽  
Absence Of Evidence ◽  
Metaphorical Extension ◽  
Analogical Process

Is speech rhythmic? In the absence of evidence for a traditional view that languages strive to coordinate either syllables or stress-feet with regular time intervals, we consider the alternative that languages exhibit contrastive rhythm subsisting merely in the alternation of stronger and weaker elements. This is initially plausible, particularly for languages with a steep ‘prominence gradient’, i.e. a large disparity between stronger and weaker elements; but we point out that alternation is poorly achieved even by a ‘stress-timed’ language such as English, and, historically, languages have conspicuously failed to adopt simple phonological remedies that would ensure alternation. Languages seem more concerned to allow ‘syntagmatic contrast’ between successive units and to use durational effects to support linguistic functions than to facilitate rhythm. Furthermore, some languages (e.g. Tamil, Korean) lack the lexical prominence which would most straightforwardly underpin prominence of alternation. We conclude that speech is not incontestibly rhythmic, and may even be antirhythmic. However, its linguistic structure and patterning allow the metaphorical extension of rhythm in varying degrees and in different ways depending on the language, and it is this analogical process which allows speech to be matched to external rhythms.

Processing and Excellent Oxidation Resistance of Nanocrystalline Fe-Cr Alloys

2010 ◽  
Vol 654-656 ◽  
pp. 1122-1125
Author(s):  
Rajeev K. Gupta ◽  
B.V. Mahesh ◽  
R.K. Singh Raman ◽  
Carl C. Koch
Keyword(s):  
Oxidation Resistance ◽  
Secondary Ion Mass Spectrometry ◽  
Nanocrystalline Alloy ◽  
High Energy ◽  
Processing Route ◽  
Protective Oxide ◽  
Time Intervals ◽  
Regular Time ◽  
Order Of Magnitude ◽  
Energy Ball

Nanocrystalline and microcrystalline Fe-10Cr alloys were prepared by high energy ball milling followed by compaction and sintering, and then oxidized in air for 52 hours at 400°C. The oxidation resistance of nanocrystalline Fe-10Cr alloy as determined by measuring the weight gain after regular time intervals was compared with that of the microcrystalline alloy of same chemical composition (also prepared by the same processing route and oxidized under identical conditions). Oxidation resistance of nanocrystalline Fe10Cr alloy was found to be in excess of an order of magnitude superior than that of microcrystalline Fe10Cr alloy. The paper also presents results of secondary ion mass spectrometry of oxidized samples of nanocrystalline and microcrystalline Fe-Cr alloys, evidencing the formation of a more protective oxide scale in the nanocrystalline alloy.

scholarly journals Spatial structures and directionalities in Monsoonal precipitation over South Asia

2010 ◽  
Vol 17 (5) ◽  
pp. 371-381 ◽  
Author(s):  
N. Malik ◽  
N. Marwan ◽  
J. Kurths
Keyword(s):  
Indian Subcontinent ◽  
Monsoon Season ◽  
Daily Rainfall ◽  
Heavy Rain ◽  
Data Sets ◽  
Spatial Structures ◽  
Break Phase ◽  
Rainfall Events ◽  
Monsoonal Precipitation ◽  
Rain Events

Abstract. Precipitation during the monsoon season over the Indian subcontinent occurs in form of enormously complex spatiotemporal patterns due to the underlying dynamics of atmospheric circulation and varying topography. Employing methods from nonlinear time series analysis, we study spatial structures of the rainfall field during the summer monsoon and identify principle regions where the dynamics of monsoonal rainfall is more coherent or homogenous. Moreover, we estimate the time delay patterns of rain events. Here we present an analysis of two separate high resolution gridded data sets of daily rainfall covering the Indian subcontinent. Using the method of event synchronization (ES), we estimate regions where heavy rain events during monsoon happen in some lag synchronised form. Further using the delay behaviour of rainfall events, we estimate the directionalities related to the progress of such type of rainfall events. The Active (break) phase of a monsoon is characterised by an increase(decrease) of rainfall over certain regions of the Indian subcontinent. We show that our method is able to identify regions of such coherent rainfall activity.

A Method for Quantitative Analysis of the Kinematics of Fibroblast Migration in a Monolayer Wound Model

2011 ◽  
Author(s):  
Gil Topman ◽  
Orna Sharabani-Yosef ◽  
Amit Gefen
Keyword(s):  
Wound Healing ◽  
Cell Migration ◽  
Wound Healing Assay ◽  
Complete Coverage ◽  
Time Intervals ◽  
Fibroblast Migration ◽  
Wound Model ◽  
Regular Time

A wound healing assay is simple but effective method to study cell migration in vitro. Cell migration in vitro was found to mimic migration in vivo to some extent [1,2]. In wound healing assays, a “wound” is created by either scraping or mechanically crushing cells in a monolayer, thereby forming a denuded area. Cells migrate into the denuded area to complete coverage, and thereby “heal” the wound. Micrographs at regular time intervals are captured during such experiments for analysis of the process of migration.

scholarly journals Using approximate Bayesian inference for a “steps and turns” continuous-time random walk observed at regular time intervals

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e8452
Author(s):  
Sofia Ruiz-Suarez ◽  
Vianey Leos-Barajas ◽  
Ignacio Alvarez-Castro ◽  
Juan Manuel Morales
Keyword(s):  
State Space ◽  
Continuous Time ◽  
Time Scale ◽  
Animal Movement ◽  
State Space Model ◽  
Movement Direction ◽  
Time Intervals ◽  
Space Model ◽  
Regular Time ◽  
Approximate Bayesian

The study of animal movement is challenging because movement is a process modulated by many factors acting at different spatial and temporal scales. In order to describe and analyse animal movement, several models have been proposed which differ primarily in the temporal conceptualization, namely continuous and discrete time formulations. Naturally, animal movement occurs in continuous time but we tend to observe it at fixed time intervals. To account for the temporal mismatch between observations and movement decisions, we used a state-space model where movement decisions (steps and turns) are made in continuous time. That is, at any time there is a non-zero probability of making a change in movement direction. The movement process is then observed at regular time intervals. As the likelihood function of this state-space model turned out to be intractable yet simulating data is straightforward, we conduct inference using different variations of Approximate Bayesian Computation (ABC). We explore the applicability of this approach as a function of the discrepancy between the temporal scale of the observations and that of the movement process in a simulation study. Simulation results suggest that the model parameters can be recovered if the observation time scale is moderately close to the average time between changes in movement direction. Good estimates were obtained when the scale of observation was up to five times that of the scale of changes in direction. We demonstrate the application of this model to a trajectory of a sheep that was reconstructed in high resolution using information from magnetometer and GPS devices. The state-space model used here allowed us to connect the scales of the observations and movement decisions in an intuitive and easy to interpret way. Our findings underscore the idea that the time scale at which animal movement decisions are made needs to be considered when designing data collection protocols. In principle, ABC methods allow to make inferences about movement processes defined in continuous time but in terms of easily interpreted steps and turns.

scholarly journals Automatic Target Acquisition and Bull Tracker using Gps and Gsm Technology

2020 ◽  
Vol 9 (3) ◽  
pp. 2776-2779
Keyword(s):  
Real Time ◽  
Mobile Application ◽  
Tracking System ◽  
Target Acquisition ◽  
Time Intervals ◽  
Regular Time ◽  
Arduino Microcontroller

An efficient bull tracking system is designed and implemented for tracking the movement of any bull from any location at any time. The designed device works using GPS and GSM technology for bull tracking. Arduino microcontroller is used to control the GPS and GSM module. The device is embedded on a bull whose position is to be determined and tracked in real time. The microcontroller is used to control the GPS module to get the coordinates at regular time intervals. The GSM module is used to transmit the updated coordinates of bull location to the client via SMS and mobile application. When the SMS is received, the app will automatically read the SMS and update the location of the bull to the user. This device will help the user to always keep an eye on their bull.

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