TL Measurements Research Articles

P724 Delaying an infliximab infusion by more than 3 days is associated with a significant reduction in trough levels

Abstract Background An association between higher infliximab-trough-levels (TL) and better outcomes has been demonstrated among IBD patients. Although standard scheduled infliximab therapy regimen consists of infusions at pre-defined time-points (weeks 0, 2, 6 and every 8 weeks), short-period deviations from therapeutic schedule are common in ‘real life’, especially during maintenance period (due to weekends, holidays, concurrent illnesses, etc.). We aimed to determine whether short-period deviations from infusion-schedule affect infliximab-TL and therapy outcome. Methods This was a retrospective study, analysing sera from all IBD patients receiving infliximab maintenance-therapy every 8 weeks in a tertiary medical centre. Associations between time since last infusion and TL were analysed. Clinical scores were recorded prospectively on infusion days and baseline demographic parameters were derived from patients’ charts. Statistical analysis was performed using generalised estimating equations. Results In total, 2088 sera of 302 maintenance-period infliximab-therapy-patients were included (median TL 4.1 μg/ml, IQR 2.3–6.5 μg/ml). A delay beyond 3 days in infusion (n > 59 days since last infusion) was demonstrated as significantly affecting TL (mean difference in TL 1 μg/ml, 95% CI 0.03–1.9 μg/ml, p < 0.04). A sub-analysis was performed for 60 maintenance-period infliximab-therapy-patients with >10 consecutive TL measurements (1226 measurements in total), with adjustment for background parameters (gender, infliximab dose, disease type, concomitant immunomodulator, age and weight). A delay of >4 days from scheduled infusion resulted in a statistically significant decline in infliximab trough levels (mean difference in TL 1.45 μg/ml, 95% CI 0.61–2.2 μg/ml, p < 0.001). Finally, deviation from infusion schedule was analysed in association with clinical remission status. Patients that were in clinical remission were more likely to arrive late, rather than early, for scheduled therapy, compared with patients with active disease (OR 2.92 CI 1.75–4.85, p < 0.0001). Conclusion Real life delays of <4 days from infusion protocol can probably be allowed. Delays beyond that would significantly decrease TL and might negatively affect therapy outcome. As patients arriving late for an infusion had higher rates of clinical remission than those arriving early, we assume clinical factors mainly drive patients to receive an earlier-then-scheduled infusion.

Primary standardization of 224Ra activity by liquid scintillation counting

A standard for activity of 224Ra in secular equilibrium with its progeny has been developed, based on triple-to-double coincidence ratio (TDCR) liquid scintillation (LS) counting. The standard was confirmed by efficiency tracing and 4παβ(LS)-γ(NaI(Tl)) anticoincidence counting, as well as by 4πγ ionization chamber and NaI(Tl) measurements. Secondary standard ionization chambers were calibrated with an expanded uncertainty of 0.62% (k = 2). Calibration settings were also determined for a 5 mL flame-sealed ampoule on several commercial reentrant ionization chambers (dose calibrators).

A Monte Carlo Method for Determining the Response Relationship between Two Commonly Used Detectors to Indirectly Measure Alpha Particle Radiation Activity.

Using targeted ligands to deliver alpha-emitting radionuclides directly to tumor cells has become a promising therapeutic strategy. To calculate the radiation dose to patients, activities of parent and daughter radionuclides must be measured. Scintillation detectors can be used to quantify these activities; however, activities found in pre-clinical and clinical studies can exceed their optimal performance range. Therefore, a method of correcting scintillation detector measurements at higher activities was developed using Monte Carlo modeling. Because there are currently no National Institute of Standards and Technology traceable Actinium-225 (225Ac) standards available, a well-type ionization chamber was used to measure 70.3 ± 7.0, 144.3 ± 14.4, 222.0 ± 22.2, 299.7 ± 30.0, 370.0 ± 37.0, and 447.7 ± 44.7 kBq samples of 225Ac obtained from Oak Ridge National Lab. Samples were then placed in a well-type NaI(Tl) scintillation detector and spectra were obtained. Alpha particle activity for each species was calculated using gamma abundance per alpha decay. MCNP6 Monte Carlo software was used to simulate the 4π-geometry of the NaI(Tl) detector. Using the ionization chamber reading as activity input to the Monte Carlo model, spectra were obtained and compared to NaI(Tl) spectra. Successive simulations of different activities were run until a spectrum minimizing the mean percent difference between the two was identified. This was repeated for each sample activity. Ionization chamber calibration measurements showed increase in error from 3% to 10% as activities decreased, resulting from decreasing detection efficiency. Measurements of 225Ac using both detector types agreed within 7% of Oak Ridge stated activities. Simulated Monte Carlo spectra of 225Ac were successfully generated. Activities obtained from these spectra differed with ionization chamber readings up to 156% at 147.7 kBq. Simulated spectra were then adjusted to correct NaI(Tl) measurements to be within 1%. These were compared to ionization chamber readings and a response relationship was determined between the two instruments. Measurements of 225Ac and daughter activity were conducted using a NaI(Tl) scintillation detector calibrated for energy and efficiency and an ionization chamber calibrated for efficiency using a surrogate calibration reference. Corrections provided by Monte Carlo modeling improve the accuracy of activity quantification for alpha-particle emitting radiopharmaceuticals in pre-clinical and clinical studies.

Quartz thermoluminescence spectra in the high-dose range

The red thermoluminescence (RTL) emission of quartz is associated with advantageous features such as high saturation dose and good reproducibility. Previous studies, however, noted inexplicable RTL glow curve shapes with new peaks at large doses (kGy range). Here we present TL spectra of two granitic quartz samples over the additive γ-dose range 0.1–47.9 kGy. While for doses between 0.4 and 1 kGy the TL spectra are dominated by the red emission at 1.95 eV (630 nm), a blue emission at 2.67 eV (465 nm) becomes prominent for higher doses. For one sample, this blue component completely dominates the spectrum for doses > 12.2 kGy with intensity maxima around 200 °C and > 350 °C (heating rate 2 K s−1). The other sample still contains well resolvable red and blue emissions at the largest dose with similar TL peak positions. Signal saturation for the blue emission in the glow curve range 260–300 °C is not yet reached following an additive γ-dose of 47.9 kGy, whereas the red emission generally shows a more subdued signal response for doses > 5–12 kGy. These findings agree qualitatively with additional monochromatic blue and red TL measurements on the same samples. The evolution of supplementary radiofluorescence spectra over the entire γ-dose range is more complex, but suggests that the sensitisation of the blue wavelength region occurs during heating and not during irradiation and through creation of electron traps rather than recombination centres (most likely [AlO4]0 sites). The sharp sensitivity increase at 1 kGy might likewise be related to alkali ion redistribution and/or the removal of non-radiative competitive recombination pathways. While the blue emission still requires thorough investigation, care should be taken when recording RTL using optical filters since significant portions of the registered TL could originate from the blue component entering the RTL transmission window. In practical terms, the dose-dependent change in relative intensities of blue and red TL emissions might help in detecting exposure to high doses.

Distinguishing Ore Deposit Type and Barren Sedimentary Pyrite Using Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry Trace Element Data and Statistical Analysis of Large Data Sets

Faced with ongoing depletion of near-surface ore deposits, geologists are increasingly required to explore for deep deposits or those lying beneath surface cover. The result is increased drilling costs and a need to maximize the value of the drill hole samples collected. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) analysis of pyrite is one tool that is showing promise in deep exploration. Since the trace element content of pyrite approximates the composition of the fluid from which it precipitated and the crystallization mechanism, the trace element characteristics can be used to predict the type of deposit with which a pyritic sample is associated. This possibility, however, is complicated by overlapping trace element abundances for many deposit types. The solution lies with simultaneous comparison of multiple trace elements through rigorous statistical analysis. Specifically, we used LA-ICP-MS pyrite trace element data and Random Forests, an ensemble machine learning supervised classifier, to distinguish barren sedimentary pyrite and five ore deposit categories: iron oxide copper-gold (IOCG), orogenic Au, porphyry Cu, sedimentary exhalative (SEDEX), and volcanic-hosted massive sulfide (VHMS) deposits. The preferred classifier utilizes in situ Co, Ni, Cu, Zn, As, Mo, Ag, Sb, Te, Tl, and Pb measurements to train the Random Forests. Testing of the Random Forests classifier using additional data from the same deposits and sedimentary basins (test data set) yielded an overall accuracy of 91.4% (94.9% for IOCG, 78.8% for orogenic Au, 81.1% for porphyry Cu, 93.6% for SEDEX, 97.2% for sedimentary pyrite, 91.8% for VHMS). Similarly, testing of the Random Forests classifier using data from deposits and sedimentary basins that did not have analyses in the training data set yielded an overall accuracy of 88.0% (81.4% for orogenic Au, 95.5% for SEDEX, 90.0% for sedimentary pyrite, 73.9% for VHMS; insufficient data was available to perform a blind test on porphyry Cu and IOCG). The performance of the classifier was further improved by instituting criteria (at least 40% of total votes from the Random Forests needed for a conclusive identification) to remove uncertain or inconclusive classifications, increasing the classifier’s accuracy to 94.5% for the test data (94.6% for IOCG, 85.8% for orogenic Au, 87.8% for porphyry Cu, 95.4% for SEDEX, 98.5% for sedimentary pyrite, 94.6% for VHMS) and 93.9% for the blind test data (85.5% for orogenic Au, 96.9% for SEDEX, 96.7% for sedimentary pyrite, 84.6% for VHMS). The Random Forests classification models for pyrite trace element data can be used as a predictive modeling tool in greenfield terrains by providing an accurate indication of ore deposit type. This advance will assist mineral explorers by allowing early implementation of predictive ore deposit models when prospecting for ore deposits. Furthermore, the ability of the classifier to accurately identify pyrite of sedimentary origin will allow researchers interested in paleoenvironmental conditions of ancient oceans to effectively screen prospective samples that are affected by a hydrothermal overprint.

Dose re-evaluation in personal dosimetry using the phototransferred thermoluminescence method of LiF:Mg,Cu,Si TLD

Phototransferred thermoluminescence (PTTL) characteristics of LiF:Mg,Cu,Si, developed by the Korea Atomic Energy Research Institute, are presented as part of a simple and reliable method for dose re-evaluation that is compatible with routine personal dosimetry services. A 4.5 mm diameter 0.8 mm thick pellet-type thermoluminescence dosimeter (TLD) was used after dual-step thermal annealing at 300 °C for 10 min, and then at 260 °C for 10 min, in order to obtain thermal stability. For optimal UV illumination, samples were placed under a 254 nm ultraviolet (UV) lamp for 90 min. The PTTL signal was only lower than 2% that of the TL because of low residual signals in high-temperature deep traps. The difference of the PTTL signals between samples appeared up to two times, indicating high variation in the charge density of the deep traps between samples. Various thermal treatments were performed after each PTTL measurement to remove the residual PTTL signal. UV exposure at 250 °C for 20 min fully reset the residual PTTL signals to the same level as that after dual-step annealing. No degradation of the TL peak from repeated thermal treatments was observed until after the eighth treatment when a decrease was noticeable. The measured dose response of PTTL in the range of 1.14–51.3 mGy showed good linearity. The zero dose and minimal detectable dose of the PTTL were 1.36 ± 0.51 mGy and 1.53 mGy, respectively. The attenuation of the PTTL signal resulting from successive TL measurements was recorded to provide a correction factor for quarterly recorded TL measurements applicable to the dose re-evaluation of TLDs in routine personal dosimetry services.

Phototransferred TL properties of alumina substrates

Alumina substrates, such as those found as surface-mount resistors in mobile phones, are currently the strongest candidate as a surrogate dosimeter material in emergency radiological scenarios using luminescence techniques. However, the rate of fading of the luminescence signal (TL or OSL) imposes a limitation on their longer term use, and also increases the uncertainty in dose assessment. The potential of phototransferred thermoluminescence (PTTL) techniques to access deep traps in alumina substrate samples is reported here. A measurement procedure employing blue (470 nm) illumination was found to produce a PTTL signal with a detection limit of ca 100 mGy, but with a supralinear dose response below 10 Gy. By using a UV source with emission between 307 and 575 nm a linear dose response was obtained within this dose range, although the detection limit was higher (ca 200 mGy), partly arising from the presence of a non-radiation-induced photostimulated TL signal. Pulse annealing experiments indicate that deep traps providing a reservoir of charge are thermally accessible above 500 °C and require annealing to ca 700 °C to thermally clean them. Significantly, using blue illumination, storage experiments performed under dark conditions at room temperature indicate that the loss of charge in the deep traps accessed by the PTTL measurement procedure was less than 30% for storage periods of up to 224 days. Although the physical mechanisms associated with the transfer of charge from the deep traps probed by the PTTL measurements require further clarification, the possibility of significantly reducing the fading observed in conventional TL or OSL measurements introduces a potentially valuable tool in the use of this material for both short and long term dosimetry.

Radiofluorescence as a detection tool for quartz luminescence quenching processes

Thermal quenching is a well-known phenomenon in quartz, which describes the decrease in luminescence efficiency (light output) with sample temperature. In the present work, the UV radiofluorescence (RF) signals of three different quartz samples during cooling from 500 °C to room temperature were monitored and analysed. Resulting thermal quenching parameters W (activation energy) and K (constant) agree with published values, except for one sample. Another quenching process in quartz is the reduction of luminescence sensitivity following irradiation (dose quenching), mainly known for TL and OSL of old samples with large palaeodoses. Here, the intensity of the 110 °C TL peak and the OSL signal were used to monitor the dose quenching effect. UV-OSL and UV-TL signals are analysed and found to be very similar. The UV-RF recorded during irradiation in between repeated cycles of TL and OSL measurements differs at high doses from a continuously recorded reference signal.Furthermore, numerical simulations are presented to decipher the charge transport processes in quartz. In summary, thermal quenching simulations are capable of mimicking experimental findings and confirm that UV-RF is a valuable tool to determine thermal quenching parameters. Dose quenching simulations differ from experimental results in the high dose range but help to understand the basic principle of dose quenching: charge competition of different centres.

A detailed investigation of the TL and OSL trap properties and signal stability of commercial pharmaceutical glass containers towards their use as post-sterilization dosimeters of liquid drugs

Drug sterilization with ionizing radiation is a well-established technology, which allows the adequate sterilization of heat-sensitive pharmaceutical preparations. However, the effects of irradiated drugs on the consumer when they are introduced in the human body are still unknown. Moreover, appropriate methods and protocols for the detection of irradiated drugs have not been established yet.In two previous studies, the possibility to identify irradiated liquid-state drugs by means of TL and OSL measurements on their glass containers was explored with very promising findings. The present work complements the previous works, conducting a detailed investigation of the TL and OSL trap properties and signal stability on two types of glass containers of liquid pharmaceutical preparations.Both the TL and OSL signals are composed by several components with linear dose response up to several kGy, while their stability with time is good, since an appreciable signal remains unaffected even 6 months post irradiation in both containers.The new findings are very supportive and point towards the efficient use of the glass containers of commercial liquid drugs as probes for the post-sterilization dosimetry and accidental dosimetry of these drugs.

High-Dose TL Dosimetry of Reactor Neutrons.

Radiation dose was measured with set of TL dosimeters during checkout of neutron radiation hardness of the ORTEC preamplifier type 142A in the experiment at the MARIA nuclear reactor at the National Centre for Nuclear Research (NCBJ), Otwock-Świerk, Poland. Different types of LiF-based TL detectors have been used for measurements in order to evaluate neutron and non-neutron components of the radiation field in the reactor channel during exposure and to check their relevancy for dose measurements in the reactor environment. For high-dose evaluation a new Ultra-High-Temperature Ratio (UHTR) method established for highly sensitive LiF:Mg,Cu,P detectors has been applied. Neutron fluence evaluated from TL measurements was in good agreement with one calculated using neutron flux data during the experiment.

An introduction to the applications and bubble dynamics of the combustive sound source

The combustive sound source (CSS) is a versatile underwater sound source with an adjustable output amplitude used in underwater acoustics experiments. Unlike typical impulsive acoustic sources, CSS can maintain a wide bandwidth at low amplitude and can be tuned to operate in a band of interest. The CSS can be used as a source for low-frequency sediment characterization, array calibration, TL measurements, and when deployed on the bottom can produce seismic interface waves. In addition to stationary deployments in the water column, CSS can be deployed in a tow body. The CSS consists of a submersible combustion chamber, open to the water, which is filled with a combustive mixture that is ignited via spark. Upon ignition, the combustive mixture is converted into high temperature combustion byproducts which expand and ultimately collapse back to smaller volume than before ignition. Acoustic pulses are radiated by the bubble activity. Although the far-field acoustic propagation is generally assumed to be linear, the inherent nature of the bubble growth and collapse is a nonlinear phenomenon. Discussion will focus on the latest CSS design including functionality and acoustic output, as well as the nonlinearity of the bubble dynamics associated with a CSS event.

Phosphorescence performance of La_3GaGe_5O_16:Tb^3+ by enhancing the bridging oxygen vacancies

La3GaGe5O16:Tb3+ phosphors deliver a long color-tuning persistent luminescence arising from the defect related emission and the 4f - 4f transitions of Tb3+. The persistent luminescence color was tuned by changing the doping Tb3+ concentration. The effect of the different atmospheres on the persistent luminescence of Tb3+-doped La3GaGe5O16 was investigated. Furthermore, we modified the composition around Tb3+ by adjusting the Ge/O content and improved the performance of persistent luminescence of the La3GaGe5O16:Tb3+. The samples synthesized in the poor-oxygen atmosphere most likely exhibited more exceptional persistent phosphorescence by enhancing the oxygen vacancies. To gain insight into the trapping and releasing processes involved in the persistent luminescence, we conducted a series of TL measurements by combining with the first-principles theory calculation. In addition, more investigations were carried out to unravel the nature of traps and also to verify the rationality of the material design.

Optical depth of traps in AL2O3:C determined by the variable energy of stimulation OSL (VES-OSL) method

Standard methods of OSL measurements (CW-OSL or LM-OSL) do not allow for the direct determination of optical depth of traps. The variable energy of stimulation optically stimulated luminescence (VES-OSL) method gives such possibility. It consists in optical stimulation with the continuous increase of stimulation light energy and is analogous to the glow curve method in TL measurements. The VES-OSL curve shape and maximum position can be regulated by the stimulation photon flux, the rate of stimulation energy increase and by measurement temperature. This allows for detecting the OSL from very deep traps that give the TL signal overlapping with strong incandescence. The VES-OSL measurements carried out for Al2O3:C showed that traps having the optical depth between 2.0 and 2.8 eV are responsible for the OSL signal related to TL peak at about 200 °C. The OSL signal from the much deeper traps from the range 2.8–3.3 eV was also detected. The TL signal related do these traps cannot be detected below 500 °C.

Thermoluminescence in gallium sulfide crystals: an unusual heating rate dependence

Trap centres in gallium sulfide single crystals have been investigated by thermoluminescence measurements in the temperature range of 10–230 K. A curve-fitting method was utilized to evaluate the activation energies (52, 200 and 304 meV) of the revealed three trap centres. The heating rate dependence and trap distribution of the peaks have been studied using experimental techniques based on various heating rates and various illumination temperatures, respectively. An anomalous heating rate dependence of the high-temperature peak was found by carrying out TL measurements with various heating rates between 0.2 and 1.0 K/s. This behaviour was explained on the basis of a semi-localized transition model. Whereas normal heating rate dependence was established for low-temperature peak, that is, the TL intensity of the glow curve decreases and the peak maximum temperature shifts to higher values with increasing the heating rate. Moreover, a quasi-continuous trap distribution with the increase of activation energies from 52 to 90 meV, from 200 to 268 meV and from 304 to 469 meV for the observed three different traps was established employing the various illumination temperatures method.

The Neolithic remains of the Shuangta Site in Baicheng City, Jilin

AbstractFrom August to October 2007, the Research Center for Chinese Frontier Archaeology of Jilin University and Jilin Provincial Institute of Cultural Relics and Archaeology conducted a joint rescue excavation in the western part of the Shuangta Site in Baicheng, Jilin Province. Remains from the Phases I and II of the site belonged to the Neolithic Age. The remains of the Phase I include pits, ditches, postholes, potsherd deposits and burials. The surfaces of most of the pottery wares are plain and the shapes are not very regular, and part of the wares’ surface showed that they were constructed by clay barcoiling method. The 14C analysis of the human bones and the TL measurements of the potsherds showed that the date of these remains was at least 10ka BP, which are the earliest Neolithic remains discovered so far in Northeast China. The remains of Phase II found in this excavation were only four burials. The grave goods include pottery wares and jades; the style of the jades is very similar to that of the Hongshan Culture, but the pottery wares have distinctive local characteristics very different from that. The tombs’ structures and the burial customs have even greater differences with that of the Hongshan Culture. Therefore, these remains certainly belonged to a new archaeological culture.

Dosimetry of Esophageal radiotherapy: a phantom study

Esophageal cancer is the eighth most ordinary cancer and the sixth most common cancer between the males and ninth for females in the world; its major and effective treatment is external radiotherapy. This type of cancer can be found in different areas of esophagus including cervical, upper, middle and lower esophagus. In this treatment, healthy tissues such as the trachea, spine and sternum and even thyroid receive dose and it is important that the absorbed doses by these organs be in their tolerance dose levels. We measured the surface and depth doses in an anthropomorphic phantom using thermoluminescent dosimeters. To do so, a target volume was considered in the phantom as a primary esophageal tumor with margins of 5 cm in the distal and proximal, and 3 cm in lateral. Phantom was CT planned and treatment was performed according to patient treatment. The considered measurement locations were Eye, right and left Parotid, left and right Submandibular, left and right Thyroid, Trachea, Manubrium of Sternum and Spine. Our results show that in places located further to primary beam such as Thyroid (phase one), Trachea, Spine and Sternum, the difference between dose from TPS and TLD measurements is observed. In organs which have placed within scattered radiation, the difference is insignificant (P-value≥0.05), although some differences might cause by TLD limitations. In conclusion, the TPS calculated and TL measured doses distinguish significantly at the spine (depth), trachea (depth) and manubrium of sternum especially in phase 1 which might be due to the calculation algorithm used by the planning system which is reliable in homogeneous medium, but TL measurements were performed in the heterogeneous anthropomorphic phantom.

Synthesis and luminescence properties of a novel yellowish-pink emissive long persistent luminescence phosphor Cd2GeO4:Pr3+

Pr3+-doped Cd2GeO4 phosphors were synthesized successfully via a traditional high temperature solid-state reaction method. It showed yellowish-pink long persistent luminescence (LPL) after the short UV-irradiation. The optimal doping concentration of Pr3+ ions for the brightest photoluminescence (PL) emission and the best LPL performance were experimentally to be about 1.5% and 1mol%, respectively. The suitable trap depth for the generation of LPL was determined to be about 0.65eV. Based on TL measurements, the trapping and re-trapping processes of charge carriers were studied. A model was proposed on the basis of experimental results to explain the mechanisms of PL and LPL.

Concentrations of 90Sr in the tooth tissues 60 years after intake: results of TL measurements and applications for Techa River dosimetry

This article focuses on the study of (90)Sr in the tooth tissues of Techa riverside residents 60 years after intake. The Techa River was contaminated by radioactive wastes in the 1950s. Contamination of the river system, including water, bottom sediment, floodplain soil, and grass, depended on the distance from the source of releases. Therefore, the average (90)Sr intake was different in different settlements located downstream the river. An additional factor influencing (90)Sr accumulation in the teeth is the rate of tissue mineralization at the time of intake which depended on the donor's age at the time of releases. Measurements of (90)Sr concentration in various dental tissues (enamel, crown, and root dentin) of 166 teeth were performed about 60 years after the main intake using the method of thermoluminescence passive beta detection. The paper presents the current levels of tooth tissue contamination, and the tooth-to-tooth variability of (90)Sr concentration in tooth tissues was assessed for the tissues which were matured at the time of massive liquid radioactive waste releases into the Techa River. A model describing the expected levels of (90)Sr in matured dental tissues depending on age and intake has been elaborated for the population under study. The results obtained will be used for calculation of internal dose in enamel and for interpretation of tooth doses measured by means of the electron paramagnetic resonance method, among the population of the Techa River region.

Length–Length and Width–Length Conversion of Longnose Skate and Big Skate Off the Pacific Coast: Implications for the Choice of Alternative Measurement Units in Fisheries Stock Assessment

AbstractMost traditional fisheries models have size or stage–age relationships as their foundation. Two long‐established metrics used are FL and TL. Body length measurements are linked to age, maturity, and fecundity. Obtaining FL or TL measurements are not always convenient, especially for larger fish (>100 cm TL). Two skate species, Longnose Skate Raja rhina and Big Skate R. binoculata, were collected from commercial fishery landings along the coast of Washington State and length–length or width–length conversions were investigated for four metrics of size: TL, tail only length (TOL), interspiracular width (ISW), and interorbital width (IOW). Relationships between TL and alternative measures were examined using model II regression analyses and confirmed a strong linear relationship in all cases (R 2 > 0.94). It is likely that both TL and TOL measures have errors due to worn‐off tail portions; conversely, the ISW is nonlaborious and convenient to obtain. The ISW metric has a smaller coefficient of variation compared with IOW if we assume that both metrics have the same distribution of measurement errors. We recommend ISW as the preferred alternative metric in the assessment of large skate. The ISW will probably yield measurements that are equivalent, or potentially superior, to traditional metrics because the measurement is taken from body parts devoid of worn‐off portions.Received December 30, 2011; accepted June 13, 2013

Synthesis and characterization of Eu3+ doped SrY2O4 phosphor

The present paper reports that TL glow curve and kinetic parameter of Eu3+ doped SrY2O4 phosphor irradiated by beta source. Sample was prepared by solid state preparation method. Sample was characterized by XRD analysis and particle size was calculated by Debye–Scherrer formula. The sample was irradiated with Sr-90 beta source giving a dose of 10Gy and the heating rate used for TL measurements are 6.7°C/s. The samples display good TL peaks at 106°C, 225°C and 382°C. The corresponding kinetic parameters are calculated. The photoluminescence excitation spectrum at 247 and 364nm monitored with 400nm excitation and the corresponding emission peaks at 590, 612 and 624nm are reported.