Short-term Tracking Research Articles

Transmitter attachment and release methods for short-term shark and stingray tracking on coral reefs

This study details a simple and cost-effective means of attaching acoustic transmitters to coral reef sharks and stingrays, which potentially allows for retrieval and reuse on completion of tracks. Between 2008 and 2011, galvanised timed releases were trialled in both static field tests and on blacktip reef sharks Carcharhinus melanopterus, cowtail Pastinachus atrus, and porcupine Urogymnus asperrimus rays in Coral Bay (−23°08′41″, 113°45′53″), Western Australia. The timed releases remained attached to animals for the duration required for tracking and in four out of five deployments transmitters were recovered after release from the animals. The use of modified Rototags for sharks and stainless steel darts for stingrays allowed rapid and effective attachment to animals, with limited impact on their welfare in the short term. External attachment for short-term tracking of coral reef-associated elasmobranchs should be considered as a complementary option to internal placement of transmitters in animals either by surgery or by ingestion.

Short-term tracking of performance and health-related physical fitness in girls: The Healthy Growth in Cariri Study

The main purpose of this study was to track the performance and health-related physical fitness of girls from Brazil's Cariri region. In the “Healthy Growth in Cariri Study”, 294 girls from public and private schools were divided into four age cohorts – 8, 10, 12, and 14 years – and followed for three consecutive years, with an assessment every 6 months. Shuttle run, hand grip, standing long jump, trunk lift, curl-up, 12-min run, and fatness were used to rate physical fitness performance and health-related components on each of six occasions. Tracking was done in a stepwise manner, using auto-correlation, by modelling the individual history of change in performance of each girl, and using Foulkes and Davies’ γ-coefficient. SPSS 18.0 and TIMEPATH were used for data analysis. Auto-correlations evidenced low-to-moderate values in almost all components of performance and health-related physical fitness. Intra-individual tracking analysis showed large variation in all fitness components as a result of a wide spread in individual history of change in fitness performance. Population estimates of γ were low in all tests. Our results show low-to-moderate tracking of physical fitness components of girls. A wide range of intra-individual and inter-variability in fitness development was observed.

160 Lung Clearance Index: short term tracking in patients with CF

160 Lung Clearance Index: short term tracking in patients with CF

Volatility Exchange-Traded Notes: Curse or Cure?

This paper investigates the trading, hedging and performance characteristics of VIX futures exchange-traded notes (ETNs) and discusses their pros and cons from the perspectives of the regulator, the issuer, and the non-speculative investor. Is this direct trading of volatility in very high volumes a major new source of issuer risk and systemic risk? Or – as advertised by the issuers – do these notes provide a unique source of diversification that should be welcomed by investors and regulators alike? To answer these questions we replicate the ETNs daily indicative values from March 2004 – March 2012, showing that the amplitude and frequency of volatility cycles have indeed increased markedly since the introduction of VIX futures ETNs. On the other hand, we explain how long-term investors can build simple ETN portfolios with uniquely attractive performance and diversification characteristics – provided they hold inverse rather than direct short-term tracker ETNs. Then we focus on the ETN issuers’ hedging activities, where the terms and conditions of early redemption provide transparent front-running opportunities for speculators which in turn increases both the hedging error and the volatility of VIX futures. Furthermore the one-day notice period for early redemption presents a moral hazard problem for the issuer.

Quantum Dots Do Not Affect the Behaviour of Mouse Embryonic Stem Cells and Kidney Stem Cells and Are Suitable for Short-Term Tracking

Quantum dots (QDs) are small nanocrystals widely used for labelling cells in order to enable cell tracking in complex environments in vitro, ex vivo and in vivo. They present many advantages over traditional fluorescent markers as they are resistant to photobleaching and have narrow emission spectra. Although QDs have been used effectively in cell tracking applications, their suitability has been questioned by reports showing they can affect stem cell behaviour and can be transferred to neighbouring cells. Using a variety of cellular and molecular biology techniques, we have investigated the effect of QDs on the proliferation and differentiation potential of two stem cell types: mouse embryonic stem cells and tissue-specific stem cells derived from mouse kidney. We have also tested if QDs released from living or dead cells can be taken up by neighbouring cells, and we have determined if QDs affect the degree of cell-cell fusion; this information is critical in order to assess the suitability of QDs for stem cell tracking. We show here that QDs have no effect on the viability, proliferation or differentiation potential of the two stem cell types. Furthermore, we show that the extent of transfer of QDs to neighbouring cells is <4%, and that QDs do not increase the degree of cell-cell fusion. However, although the QDs have a high labelling efficiency (>85%), they are rapidly depleted from both stem cell populations. Taken together, our results suggest that QDs are effective cell labelling probes that are suitable for short-term stem cell tracking.

14.1 T whole body MRI for detection of mesoangioblast stem cells in a murine model of duchenne muscular dystrophy

Noninvasive imaging procedures will be important for stem cell therapy for muscular dystrophy (MD). Mesoangioblasts regenerate muscle in animal models of muscular dystrophy. In this study, superparamagnetic iron oxide nanoparticles were used to visualize mesoangioblasts in vivo with MRI. Mesoangioblasts incorporated superparamagnetic iron oxide without transfection reagents, and cell differentiation was not negatively impacted. A custom-built radiofrequency coil with an adjustable field of view and 14.1 T magnet were used for whole-body MRI of mice. High-resolution images of mesoangioblasts in skeletal and cardiac muscle of Mdx mice were obtained following local delivery. Labeled cells were verified by Prussian blue staining and dystrophin expression, indicating that the wild-type mesoangioblasts survived and differentiated in muscle. Iron-labeled cells were detected with MRI in vivo 6 months following intracardiac injection but were determined to be activated macrophages. Iron-labeled cells were not detected by MRI following systemic delivery but were present in skeletal and cardiac muscle, visualized by Prussian blue staining. Systemically delivered mesoangioblasts were detected in lungs by Prussian blue staining and DiI but not by MRI in our study. MRI may be useful for short-term tracking of mesoangioblasts delivered locally but not for long-term monitoring or detection after systemic delivery.

Watch your time step: trapping and tracking dispersal in autocorrelated environments

Summary 1. Reliable estimates of dispersal kernels are needed for many applications in ecology. For both plants and animals, and for passive and active dispersal, the two most common methods for obtaining dispersal kernel estimates from direct measurements are following individual propagules (tracking) and counting propagules at fixed locations (trapping). 2. We consider the effect of the chosen sampling method on the estimation of dispersal kernels and highlight reasons why we should not necessarily expect estimates from the two methods to be the same. We illustrate this point using data from field experiments for three wind-dispersed plant species (Carduus nutans, Carduus acanthoides and Crepis praemorsa) and a mechanistic dispersal model (WALD). 3. The field experiments demonstrate that the two sampling methods lead to different dispersal kernel estimates. Although estimated mean dispersal distances may be similar, short-term tracking studies with random seed release generally lead to more peaked distributions with greater modal dispersal distances than long-term trapping of naturally dispersing seeds. 4. Wind speed data and dispersal distributions estimated using the mechanistic dispersal model suggest that differences between the sampling methods arise from temporally autocorrelated environmental conditions interacting with study time frame and dispersal initiation processes. Single tracking events tend to provide biased estimates of wind statistics because of short-term autocorrelation in wind speeds. Depending on the long-term autocorrelation structure of wind speeds, and the sampling of wind speeds compared to natural seed release, single short-term tracking studies may result in distributions that differ strongly from the ‘true’ distribution sampled by trapping over the dispersal season. Distributions from several tracking studies, weighted according to natural dispersal initiation, may therefore be needed to recapture the true dispersal distribution. 5. This study demonstrates that commonly used sampling methods for dispersal can result in dramatically different distributions under temporally autocorrelated environmental conditions. As autocorrelated environments are ubiquitous, this could lead to marked biases in predictions of movement and spread. These results are relevant for a wide range of ecological systems and to theoretical and applied problems relying on measurements and models of dispersal, for instance, conservation in fragmented landscapes, biological invasions and species re-introductions. The measurement process should be taken into account in such applications.

The Jump Risk of Leveraged ETFs and a High-Frequency Volatility Estimator

This paper is the first to characterize the intraday performance of leveraged exchange-traded funds (ETFs), for which I introduce a superior volatility estimator for high-frequency analysis. Leveraged ETFs, which attempt to reproduce two or three times the daily performance of their underlying indices, experienced a growth boom during the global financial crisis of 2008-09. Just a few months after their launch in November 2008, Direxion’s triple-leveraged long and short financials ETFs were among the five most actively traded stocks in the United States. By construction, leveraged ETFs have some tracking error compared to their underlying indices over longer holding periods, which has been the focus of extant research. The short-term tracking error of leveraged ETFs is more relevant because traders only hold them for a few days, so I examine it by modifying the nonparametric jump detection test of Lee and Mykland (2008) with a new bipower variation-based subsampling and averaging high-frequency volatility estimator. Tracking error jumps are found to occur in one-fourth of trading days for leveraged ETFs that track the S&P 500 index and financial sector, and the economic significance of jump risk is substantial. Tracking error jump risk can be largely avoided, but jumps that do occur are difficult to predict.

WE‐B‐213A‐01: Medical Response to a Radiological/Nuclear Event

Planning for and exercising the medical response to potential mass casualty radiological and nuclear (rad/nuc) events from accidents or terrorism are very new responsibilities for most physicians, nurses, emergency medical technicians/paramedics and other healthcare professionals. Many medical professional societies are attempting to define the essential knowledge base and performance skills needed to certify readiness and competence in this area of disaster medicine.Medical physicists and the entire spectrum of radiation safety professionals have critical expertise needed for event preparedness. They can• Help educate medical personnel to understand radiation issues and gain comfort with techniques and procedures needed to perform effectively and safely• Help develop appropriate response plans if plans are non‐existent or inadequate, and assist with iterative plan improvement and assessment in formal exercises• Identify, procure, store, and maintain required response equipmentDuring events they will help protect first responders, victim transport personnel, and first receivers in hospitals and other medical facilities along the entire continuum of the medical response. Radiation safety professionals may be asked to• Assist event managers and security personnel in establishing safe response zones• Supervise or perform radiation surveys of victims and responders• Assist with estimates of absorbed dose received by both victims and responders,• Support the implementation of appropriate protective actions• Participate in the collection and transport of radiation bioassays for contamination• Supervise decontamination of victims and responders• Assist with short and long term tracking of both victims and respondersThreat analysis has identified a list of isotopes of potential concern for mass casualty events. Selected medical countermeasures will be recommended for victims with certain levels of contamination and/or exposure.For physics professionals planning to assist in rad/nuc mass casualty responses, knowledge about existing Federal, State, and local medical response plans in your area is crucial. Implementation of the Hospital Incident Command System will integrate medical activities with other response activities, including public information, forensics, and security.This lecture will provide an overview of• The kinds of mass casualty rad/nuc events that have received the most attention from homeland security and medical planners• The isotopes of concern for mass casualty events• Available radiation countermeasures for exposure and contamination• Some of the issues surrounding the assessment of contamination and performance of decontamination in mass casualty events• The “radiation response zones” likely to be established during certain events• Suggestions for initiating and equipping rad/nuc medical response teams in your hospital• How to volunteer to be on rad/nuc response teams• A bibliography of useful publications and web sitesLearning objectives: After attending this lecture, students will be able to1. Describe the radiological and nuclear events of greatest concern to US government response planners2. Identify isotopes of concern and medical countermeasures likely to be associated with various kinds of events3. Identify the radiation zones likely to be associated with managing the response to a nuclear detonation

Noise mapping in Portland Oregon: The need to develop an approach to accurately depict the health impacts of short duration automotive racing noises emanating from a variety of motorized race events at the Portland International Racetrack facility.

The City of Portland Oregon is in the final phase of completing its efforts to map one quadrant of the city in conjunction with the Greenbusch Group of Seattle Washington. The selection of this section of the city was identified for its notable concentration of noise sources ranging from the normal transportation related road, railway, and international airport sounds, to the unique and constantly varying tonal quality of automobile and motorcycle race groups at an international automotive raceway facility. The challenge to identify an appropriate method or standard to accurately depict the impact of these short term track races and drag races offers a unique opportunity to expand on the value of the noise mapping approach for long term urban planning efforts.

Predictors of body mass index change in Australian primary school children

To assess associations between multiple potential predictors and change in child body mass index (BMI). In the 1997 Health of Young Victorians Study, children in Grades preparatory to three (aged 5-10 years) had their height and weight measured. Parents provided information on potential predictors of childhood overweight across six domains (children's diet, children's activity level, family composition, sociodemographic factors, prenatal factors and parental adiposity). Measures were repeated three years later in 2000/1. BMI was transformed to standardised (z) scores using the US 2000 Growth Chart data and children were classified as non-overweight or overweight according to international cut-points. Regression analyses, including baseline BMI z-score as a covariate, assessed the contribution of each potential predictor to change in BMI z-score, development of overweight and spontaneous resolution of overweight in 1,373 children. BMI z-score change was positively associated with frequency of take-away food, food quantity, total weekly screen time, non-Australian paternal country of birth, maternal smoking during pregnancy, and maternal and paternal BMI. Inverse associations were noted for the presence of siblings and rural residence (all p<0.05). Predictors of categorical change (development and resolution of overweight) were less clearly identified, apart from an association between maternal BMI and overweight development (p=0.02). Multivariable models suggested individual determinants have a cumulative effect on BMI change. Strong short-term tracking of BMI makes it difficult to identify predictors of change. Nonetheless, putative determinants across all domains assessed were independently associated with adiposity change. Multi-faceted solutions are likely to be required to successfully deal with the complexities of childhood overweight.

In Vivo Imaging to Monitor Trafficking and Engraftment of Human CD34+ Hematopoietic Stem and Progenitor Cells in Rhesus Monkeys

Significant advancements have been made in the use of noninvasive imaging techniques which includes dramatic improvements in resolution and sensitivity, and imaging systems designed specifically for animals. The non-invasive nature of these techniques allows longitudinal assessments over time, and the evaluation of protocols that could be applied in a human clinical setting. Imaging is also of great utility in situations when it is unclear where to focus the analyses, such as the challenges presented by systemic administration of transplanted cells, which can traffic to different anatomical sites. Our prior studies have shown that we can monitor gene expression in fetal and infant monkeys using reporter genes, microPET, and optical imaging. We have also shown that human mobilized peripheral blood stem cells (hPBSC) from adult male donors and male cord blood CD34+ hematopoietic stem cells (HSC) can readily engraft in fetal rhesus monkeys and persist over time. Other recent findings suggest that growth factor expansion of cord blood CD34+ HSC in vitro prior to transplant substantially increases the level of engraftment, with evidence of human hematopoietic cells in the rhesus host at levels significantly greater than the approximate 2% we previously reported. Our studies have also focused on new ways to use optical imaging to monitor transplanted hPBSC, cord blood HSC, and CD34+ precursors differentiated from human embryonic stem cells (hESC) that express firefly luciferase and a drug resistance gene, and the development of PET techniques for short-term tracking of transplanted cells. Transduced cells (1×104–20×106 cells/fetus) were transplanted intraperitoneally into fetal monkeys in the late first trimester under ultrasound guidance (N=27), then animals were monitored sonographically during gestation, and delivered by cesarean-section at term. At 1 week postnatal age and monthly thereafter animals were imaged for firefly luciferase expression (bioluminescence) following the intravenous injection of 100 mg/kg D-luciferin, and after the collection of blood and bone marrow for analysis. While evidence of the human Y chromosome (hSRY, hTSPY) was found in peripheral blood mononuclear cells and CD34+ immunoselected cells from marrow by qRT-PCR, the range of copies detected over time did not reflect the imaging findings. Foci of engrafted human cells were found to persist for ≥1 year, to date, in the rhesus host and in anatomical areas not previously identified (e.g., ribs, sternum, liver). In addition, 64Cu-PTSM radiolabeled hPBSC from the same donors were injected postnatally and cell trafficking monitored without evidence of toxicity or adverse effects. These in vivo imaging studies have provided unique insights into the fate of CD34+ cells post-transplantation, and indicate the importance of these techniques for cell transplant protocols.

Creating a Smarter Conditional Consensus Forecast

We examine analyst forecasts of 26 macroeconomic statistics over the August 1998 to March 2007 time period. We pose four research questions: (1) Does forecast accuracy persist?; (2) What are the determinants of such persistence?; (3) Do analysts who exhibit these characteristics make more accurate forecasts than the simple consensus?; and (4) Is a consensus based on individuals exhibiting these characteristics more accurate than the simple consensus? We show that analyst forecast accuracy persists and is determined by long-term, past accuracy and the overall ability in forecasting all statistics. That is, analyst long-term track record is more important than short-term track record, and track record in forecasting other statistics (general ability) is more important than track record in forecasting the macroeconomic statistic in question (specific ability). We demonstrate that a smart consensus conditioned on forecasts of analysts with superior long-term, general ability outperforms commonly reported mean and median consensus forecasts.

Short-term predictors of abdominal obesity in children

The aim of this study was to examine the short-term tracking of abdominal adiposity in children. A total of 918 children (477 boys) aged 6-12 years at baseline were followed-up for 2 years. Central obesity was assessed by waist circumference (WaistC), whereas body fat distribution by waist-to-hip ratio. Maturity was assessed by the Khamis-Roche method. Parental fatness and children's cardiorespiratory fitness (CRF) were also evaluated. Multiple and logistic regressions were employed to identify the predictors of BMI and WaistC. Tracking of body fatness and body fat distribution was high (r = 0.69-0.86, P < 0.01). More boys remained obese than girls (P < 0.05), whereas a greater percentage of boys moved to a higher quartile of WaistC after the 2-year follow-up (22.0 vs 14.1%, P < 0.01). Sex, child's maturity and WaistC at baseline, CRF, and maternal BMI explained 76% of the variability in BMI and WaistC at the follow-up (n = 290). Children with high WaistC at baseline and low CRF presented 1.9- and 4.3-fold increased risk of remaining in the upper quartile of WaistC at the follow-up (P < 0.01; n = 552). Youth with increased WaistC at baseline and low CRF presented an increased chance of maintaining central obesity at the follow-up. More boys than girls moved into a higher quartile of abdominal obesity during the 2-year follow-up period and this should be taken into account in designing programmes for childhood obesity.

In Situ Tagging and Tracking of Coral Reef Fishes from the Aquarius Undersea Laboratory

We surgically implanted coded-acoustic transmitters in a total of 46 coral reef fish during a saturation mission to the Aquarius Undersea Laboratory in August 2002. Aquarius is located within the Conch Reef Research Only Area, a no-take marine reserve in the northern Florida Keys National Marine Sanctuary. Over the course of 10 days, with daily bottom times of 7 hrs, saturation diving operations allowed us to collect, surgically tag, release, and subsequently track fishes entirely in situ. Fish were collected using baited traps deployed adjacent to the reef as well as nets manipulated on the bottom by divers. Surgical implantation of acoustic transmitters was conducted at a mobile surgical station that was moved to different sites across the reef. Each fish was revived from anesthetic and released as divers swam the fish about the reef. Short-term tracking of tagged fish was conducted by saturation divers, while long-term fish movement was recorded by a series of acoustic receivers deployed on the seafloor. Though not designed as an explicit comparison with surface tagging operations, the benefits of working entirely in situ were apparent.

Retention and effects of nasal markers and subcutaneously implanted radio transmitters on breeding female Lesser Scaup

Forty-seven wild female Lesser Scaup (Aythya affinis) were marked with nasal markers and radio transmitters (implanted subcutaneously on the back) just prior to breeding near Yellowknife, Northwest Territories, in 1999 and 2000. Retention rates of both marker types were evaluated, and their effects on specific behavior categories were assessed by comparison of marked birds with unmarked control birds. Significant effects of nasal markers on behavior were detected; females often removed vegetation from nasal markers after diving, and consequently marked females tended to shake their head more frequently than unmarked birds. No nasal markers were lost during the study. Five females lost radios, producing an average retention time of 39 d. Daily retention rate was 0.997, being 0.85 when extrapolated to 60 d. The survival rate of 42 females radio-tracked consistently was constant for six 7-d intervals, suggesting no immediate adverse effect on survival. Because the technique is invasive, use of subcutaneous transmitters may not be appropriate for all applications, but it could be a preferred alternative to other transmitter-attachment methods for short-term tracking of waterfowl.

A correlation–regression method for tracking rainstorms using rain-gauge data

This paper focuses on the short-term tracking of rainstorms, using data from a network of 20 tipping-bucket rain-gauges located in a 600 km 2 region near Bolton in Northwest England. The tip-time data are first converted into rainrate profiles (the moving averages of hourly rainrates). The cross-correlation between pairs of profiles is examined to obtain estimated inter-gauge lags. Estimates from gauges that correlate poorly are discarded, since these gauges may be malfunctioning. The remaining estimated lags are modelled using linear dependencies on the spatial displacements of the gauge-pairs and the velocity of the rainstorm is deduced using standard formulae. Sums of squared deletion residuals give a second opportunity for identifying gauges associated with misleading estimates. Empirical confidence intervals are obtained by multiple analyses using different combinations of tip sequences. All rainstorms between February and December 2000 were analysed. Of these, 171 had a mean rainrate of at least 0.4 mm/h. Apparently accurate estimates of storm velocity were obtained for 107 storms. The mean speed was 34.5 km/h (9.6 m/s) with mean direction 80°.

Tracking of 24-hour and casual blood pressure: a 1-year follow-up study in adolescents.

Tracking of blood pressure begins in childhood but the relationship between casual blood pressure in childhood and adult levels is not strong enough to predict adult hypertension. The variability of blood pressure in children might suggest that 24 recordings would have less consistency than casual readings when repeated even a relatively short time later. This study compares the short-term tracking ability of casual versus 24-h blood pressure. An ambulatory blood pressure device was placed on 50 teenagers. Readings were taken at rest and the device was then worn for approximately 24 h, which included the schoolday. The protocol was repeated 1 year later. The correlation coefficient for systolic readings taken 1 year later were: 0.4 for casual, 0.6 for school, 0.6 for home, 0.5 for night-time and 0.8 for 24-h mean systolic blood pressures. When divided into upper and lower tertiles of systolic blood pressure the relationship between tertile ranking 1 year later was stronger for 24-h blood pressure than the casual readings. Casual diastolic pressure was more consistent than the 24-h mean diastolic measurement. In adolescents, in whom tracking of casual blood pressure has been shown to be poor, 24-h mean systolic blood pressure tracks better than any other time period and significantly better than the casual systolic readings. This study needs to be extended and the ability of 24-h blood pressure to track from childhood to adult life investigated.

Integrated Person Tracking Using Stereo, Color, and Pattern Detection

We present an approach to real-time person tracking in crowded and/or unknown environments using integration of multiple visual modalities. We combine stereo, color, and face detection modules into a single robust system, and show an initial application in an interactive, face-responsive display. Dense, real-time stereo processing is used to isolate users from other objects and people in the background. Skin-hue classification identifies and tracks likely body parts within the silhouette of a user. Face pattern detection discriminates and localizes the face within the identified body parts. Faces and bodies of users are tracked over several temporal scales: short-term (user stays within the field of view), medium-term (user exits/reenters within minutes), and long term (user returns after hours or days). Short-term tracking is performed using simple region position and size correspondences, while medium and long-term tracking are based on statistics of user appearance. We discuss the failure modes of each individual module, describe our integration method, and report results with the complete system in trials with thousands of users.

Propagation Delay of a Laser Beacon as a Tool to Retrieve Absolute Tilt Measurements

The knowledge of the temporal evolution of a star wandering for a limited time interval (e.g., a fraction of a second) can be used to increase dramatically the sky coverage of a laser-beacon adaptive optics system. A technique to achieve such short-term tracking is described. The full sky coverage is easily achieved by using the whole telescope as a laser projector.