bluuebunny/crossref_metadata_2025 huggingface dataset:
TH‐C‐AUD C‐06: Nearly Real‐Time Tumor‐Position Monitoring During Arc Therapy with Combined MV and KV Imaging
Authors: Liu W , Mao W , Wiersma R , Luxton G , Riaz N , Xing L
Published: July 2008

Purpose: To examine the feasibility and accuracy of using treatment MV beam and on‐board kV imaging for monitoring of the positions of implanted fiducials during arc therapy. Method and Materials: A Varian Trilogy LINAC with onboard kV imager was used for the study. A phantom with 13 ball bearings at known locations was used to calibrate the hybrid MV/kV imaging system to determine the spatial transformation matrix from the pixel coordinates to the radiation‐source‐centered coordinates. The feasibility and accuracy of the fiducial tracking system was examined using a 4D motion phantom capable of moving in accordance with a pre‐programmed trajectory. During an arc delivery, MV images acquired by the EPID and cine kV images were obtained simultaneously using a two‐channel frame‐grabber for real‐time analysis. A fast fiducial detection algorithm was developed to extract fiducial coordinates. Tracking results are compared with the preset trajectories. The accuracy of the tracking system was evaluated for a number of fiducial motion trajectories and for a variety of kV beam sampling rates ranging 15fps to 0.5fps. Results: The studies showed that it is feasible to use treatment MV beam and the orthogonal kV beam to monitor the fiducial motion in nearly real‐time during arc therapy. A time delay of ∼150ms was observed, which was caused by the imaging electronics and data analysis. This delay does not pose any significant error in fiducial tracking for the motion speed commonly seen in the clinics and can be compensated by a motion prediction algorithm when needed. Overall, the spatial accuracy was found to be better than 1mm. Conclusion: Nearly real‐time monitoring of implanted markers using hybrid MV/kV imaging during arc treatments is achievable. The system requires no hardware modification and delivers much less dose to the patient as compared with the conventional stereoscopic imaging technique.
TH‐C‐332‐09: The Effect of Variable Exposure Distribution On Microcalcification Detectability in Tomosynthesis
Authors: Lau B , Reiser I , Nishikawa R
Published: July 2008

Purpose: To investigate the fundamental limitation of tomosynthesis acquisition on the detectability of microcalcifications (MCs) and to investigate the effects of employing unequal dose distribution (variable exposure) across the tomosynthesis projections. Method and Materials: Ray tracing was used through a 5‐cm thick homogeneous slab phantom, which contained 150‐, 280‐, and 400‐micron diameter spheres embedded at the center. In this study we accounted for acquisition geometry and x‐ray quantum noise. Detectability was calculated using a nonprewhitening observer. In the sinogram data, detectability was computed by integrating observer response over all projection views. In the reconstructed image, observer response was computed using a 2D matched template at the in‐focus slice of the sphere. To test variable distribution of exposure, 50% of the exposure was concentrated in the center three projection views, and the rest was divided equally among the remaining projection views. Results: We determined that the detectability of MCs is reduced for larger projection angles because of the increased pathlength through the phantom and larger source‐to‐detector distance. The spheres are projected on the detector as ellipses at larger angles, which blurs the MCs and decreases detectability. Detectability of MCs using the variable exposure method is approximately 10–20% higher than detectability in the equal exposure distribution method. Conclusion: The detectability of MC is reduced in a tomosynthesis acquisition because of the acquisition geometry if all projections are made with the same exposure. A variable exposure method can improve MC detectability in DBT systems. In future work we will examine the effect of breast structure noise on the variable exposure method. Conflict of Interest: Research sponsored by Hologic, Inc. and Dexela Ltd.
TH‐C‐332‐10: Ultrasound Inverse‐Scatter Tomography of the Breast
Authors: Andre M , Johnson S , Borup D , Wiskin J , Barker C , Callahan K , Hanover B , Ojeda‐Fournier H , Setinsek F , Berggren M , Olsen S
Published: July 2008

Purpose: To present the design and performance of a new automated whole‐breast ultrasound computed tomography (USCT) system that employs 3D inverse‐scatter reconstruction. Method and Materials: The scanner (Techniscan Medical Systems, Inc., Salt Lake City, Utah) is installed at the University of California, San Diego to evaluate clinical performance including ability to detect and analyze breast masses. Patients lie prone on a table while opposing transmitter and receiver transducer arrays rotate 360° around the breast. Ultrasound plane waves (300 kHz–2MHz) are emitted every 2 degrees while the scattered beam is detected by a 960‐element six‐row transducer. In the same plane three B‐mode linear arrays acquire backscatter data from wideband signals (3.6–8.4 MHz). The arrays move up the breast in 2mm increments to scan the entire breast. Discrete frequency domain data is used by a proprietary 3D inverse‐scattering algorithm that incorporates multiple scattering within and between the planes. 2‐D coronal images of the entire breast are reconstructed as accurate quantitative maps of sound speed and attenuation along with aberration‐corrected high‐resolution reflection tomograms. Results: To date, more than 50 subjects were scanned with wide range in age (20–78), breast density and diagnostic outcome. Representative cases will be presented comparing mammography, sonography and multi‐planar USCT images. Included are benigns (cysts, fibroadenomas, fibrocystic disease) and biopsy‐proven malignancies (invasive ductal carcinomas, invasive tubular carcinoma and mixed lobular/ductal carcinoma). System performance and tissue characterization are excellent. Accuracy and linearity of sound speed measurements by USCT is very high (R2=0.988) over the range of 1400 to 1600 m/sec. Conclusion: The USCT system provides rapid, automated scanning with quantitative 3D images of the breast and substantially new information for characterizing breast masses. Conflict of Interest: Research sponsored in part by Techniscan Medical Systems, Inc.
TH‐C‐342‐03: Quantitative Medical Image Analysis for Early Detection, Diagnosis, Outcome Prediction, and Treatment
Authors: Sonka M
Published: July 2008

Medical imaging and image analysis has revolutionized the patient care as well as many research activities in biology and healthcare. Stet‐of‐the‐art methods and approaches for medical image segmentation, quantitative analysis, and their use for computer‐aided diagnosis and disease progression prediction will be the main target of this presentation. Special focus will be given to several high‐complexity projects in the areas of coronary image analysis via fusion of intravascular ultrasound and angiography, coronary plaque analysis, plaque progression prediction, cardiovascular risk factor assessment via analysis of carotid and brachial ultrasound images, pulmonary CT image analysis, computer‐aided diagnosis of congenital aortic disease, cartilage MR image analysis, and liver surgery planning. The talk will be accompanied by live demonstrations of the software tools developed for the above‐referenced purposes.
TH‐C‐352‐01: Clinical Introduction and Use of LDR — the Anatomy of a Prostate Case
Authors: Miller R
Published: July 2008

The development of Brachytherapy began with the purification of radium by Pierre and Marie Curie. Due to early clinical practice using Radium, several systems were developed to standardize the practice as well as the emergence of different techniques: intracavitary, interstitial, intraluminal and surface molds. Brachytherapy implants can also be temporary or permanent. A list of resources will be provided covering the basics and history of Brachytherapy but the focus of this aspect of the workshop will be on the most common current utilization: permanent prostate seed implants. Topics to be covered include: isotope characteristics and selection, pre‐planning and ordering, receipt and activity verification, implantation, and post‐planning.

Educational Objectives:

1. Review the isotopes in vogue, prescription ranges, and common clinical characteristics.

2. Review isotope manufacturing and calibration issues.

3. Review of current implant techniques (Mick ® versus stranded).

4. Review radiation safety and release criteria.

5. Review post plans and lessons learned the hard way.
SU‐GG‐J‐52: Comparison of a Commercial 3D‐3D Auto‐Registration Tool Vs. Manual Alignment to the Target
Authors: Chi P , Zhang L , Dong L , Balter P
Published: July 2008

Purpose: The purpose of this project is to compare a commercial 3D‐3D auto‐registration tool vs. manual alignment to the target. Method and Materials: Cone beam computed tomography (CBCT) images were acquired immediately before patient treatments for thoracic lesions. An automatic 3D‐3D matching system (OBI, Varian Associates, Palo Alto, CA) was used to align the entire CT volume against the respiratory averaged CT from a 4DCT. The suggested shifts were recorded but were not used to treat the patient, those from an in‐house system were used. The in‐house system also allowed us to retrospectively perform a manual match using only the target and not the entire volume. The shifts between these two methods were compared for 47 weekly CBCT data‐sets acquired for 17 patients. The couch shift necessary for re‐alignment was recorded in the 3 vector components (vertical, longitudinal and lateral, rotation corrections were not used). Results: For all 47 CBCT sessions, the largest couch shift differences were 0.6 cm, 2.9 cm, and 0.8 cm in the vertical, longitudinal and lateral direction, respectively. The mean difference in the magnitude of the vector was 0.69 cm. The target volumes were further divided into 24 mediastinal cases and 23 solid tumors in the lung parenchyma. The mean difference in the couch shift vectors were 0.35 cm for mediastinum cases and 1.05 cm for solid tumor cases. The difference of 0.70 cm between the two means was significant (p < 0.0001). We believe the differences between the automatic and manual matches are due to soft tissue deformation, changes in respiratory motion, and/or the auto‐alignment cost function locking onto a local minima. Conclusion: Caution must be used when performing automated 3D‐3D matching as changes in patient anatomy and/or the occurrences of local minima in the alignment cost‐function can lead to significant geometric misses.
SU‐GG‐J‐55: Comparison of Megavoltage Imaging Modalities and Spatial Effects for Dose Calculations.
Authors: Sheth N , Murphy S , Yang C
Published: July 2008

Purpose: To investigate spatial effects of differing physical densities in megavoltage imaging with cone‐beam computed tomography (MVCB) versus helical tomotherapy (MVCT) for dose calculation. Method and Materials: Image value‐to‐density tables (IVDT) were created for MVCB and MVCT against standard kilovoltge computed tomography (KVCT) using a solid‐water phantom and varying tissue equivalent inserts. The spatial independence of the different physical densities of the image was tested by generating two sets of IVDT for each modality: one with the inserts in the peripheral locations in the phantom and another with the inserts in the inner locations. Scans of an anthropomorphic head phantom for each modality were imported into a treatment planning system; contours of anatomy were created and a seven field IMRT plan was developed to simulate treatment to a target in the brain. The dose was then calculated for each imaging modality scan corrected with its given IVDT. Results: The IVDT sets for KVCT were nearly identical to each other; the IVDT sets for MVCT were practically equal also. Such similarity was confirmed by comparing the dose volume histograms of treatment plans; average coverage of the target was 95.5±0.2%. However, the IVDT sets for MVCB exhibited an appreciable difference as the central region of the images had a lower value inaccurately reducing the density. This was reflected in the MVCB treatment plans as the prescription covered 17.75% of the target using IVDT with tissue equivalent inserts in the inner locations. This coverage was increased to 98.65% using the outer locations. Conclusion: KVCT and MVCT modalities provide images suitable for dose calculation of differing physical densities that is independent of their spatial location. However, the artifacts introduced by MVCB imaging can lead to notable differences in image values and its corresponding densities that render current MVCB unsuitable for dose calculation.
Sci‐Fri AM: YIS‐02: Evaluation of the LabPET4 imaging capabilities for in vivo small animal imaging
Authors: Bergeron M , Cadorette J , Tétrault M‐A , Viscogliosi N , Beaudoin J‐F , Selivanov V , Fontaine R , Lecomte R
Published: July 2008

Positron Emission Tomography (PET) is a non‐invasive technique to visualize metabolic and physiological processes in vivo. Excellent imaging capabilities such as spatial resolution and count rate performance are essential to achieve accurate information about the observed processes. It is for this purpose that the LabPET scanner, an avalanche photodiode (APD)‐based fully digital scanner PET scanner, was initially developed. Two variants of the scanner exist: LabPET4 and LabPET8 with 3.75 and 7.5 cm axial lengths respectively. The range of the transaxial FOV is up to 10 cm therefore it can easily accommodate mice and rats. The aim of this work is to evaluate LabPET4 imaging in several phantoms and small animals. Spatial resolution was determined using a point source and hot spots phantoms. The latter were used to assess recovery coefficients (RC) obtained by taking the ratio of hot spot maximum values compared to the biggest spot maximum value. FBP reconstructed tangential/radial resolution is 1.3/1.4 mm FWHM (2.5/2.4 FWTM) at the field of view center. With an Ultra Micro Hot Spot Phantom, 1 mm spots are clearly resolved. Count rate performance was obtained for mouse‐size and rat‐size phantoms. For mouse phantom, scatter fraction is 18%, noise equivalent count rate (NEC) peak is 120 kcps at 5.6 mCi and true coincidences peak is 215 kcps at 6.6 mCi. Mice and rats were imaged with and . LabPET4 imaging capabilities achieve state‐of‐the‐art requirements for molecular imaging and therefore can provide excellent quality images.
Sci‐Fri PM: Planning‐01: Measured electron and x‐ray angular distribution data for benchmarking Monte Carlo codes
Authors: Cojocaru CD , Ross CK , McEwen MR , McDonald AF , Faddegon BA
Published: July 2008

Monte Carlo (MC) studies of the output of medical linear accelerators have demonstrated that in‐air profiles are useful in the beam commissioning process. A recent investigation of x‐ray profiles (Tonkopi et al, Med. Phys 32 (9), 2005) showed very good agreement between measurement and EGSnrc calculations but to achieve this level of agreement the beam linac spot size, energy and angular divergence had to be treated as variables. In this project we carried out measurements and MC calculations for an electron accelerator for which the initial beam parameters are well known. Two sets of investigations were carried out. In the first we measured electron scatter distributions for a range of scattering foils and electron energies of 13 and 20 MeV. The profiles were parameterised and compared to EGSnrc Monte Carlo calculations. It was found that generally the EGSnrc calculations gave agreement with the measurements within 1.5 %. In the second investigation, which is on‐going, in‐air profiles were obtained for photon beams produced using different targets (from beryllium to lead). Measured angular distributions were obtained using ion chambers with different build‐up caps (low and high‐Z) and the sensitivity of the data to small changes in geometry (e.g., moving the x‐ray target) was investigated. The photon energy fluence was calculated using EGSnrc and preliminary indications are that the measured and calculated distributions agree to better than 5 %. Work supported in part by NIH grant R01 CA104777‐01A2.
Sci‐Fri PM: Planning‐03: Fundamental understanding of the inter‐relation of arc range, angular dose rate and MLC leaf position optimization of Intensity Modulated Arc Therapy for a concave target
Authors: Oliver M , Chen J , Wong E
Published: July 2008

Intensity Modulated Arc Therapy (IMAT) is a rotational variant of Intensity Modulated Radiation Therapy (IMRT) that can be implemented with or without angular dose rate optimization. The purpose of this study is to determine the inter‐relationship among arc range, Multi‐Leaf Collimator (MLC) leaf positions and angular dose rate optimizations for IMAT delivery of a concave target. A concave planning target volume (PTV) with central cylindrical organ at risk (OAR) was used in dissecting the inter‐relationships. Plans with full and limited arc range were generated using leaf position optimization (LPO) alone, angular dose rate optimization (ADRO) alone or LPO followed by ADRO. Two initial IMAT arcs were conformal avoidance arcs created with 5° angular increments where MLC leaf positions were determined from the beams eye view to irradiate the PTV but avoid the OAR. The objective function value (evaluating dose to PTV and OAR), a conformity index, dose homogeneity index, mean dose to OAR and normal tissues were computed and used to evaluate the treatment plans. Dose rate variations and MLC leaf movements as a function of gantry angle were examined in this approach. The results demonstrate that LPO followed by ADRO provided the lowest objective function values, best conformity and dose homogeneity indices, and third in mean dose to OAR and normal tissues for the complete arc range. Future work will address different strategies for simultaneously optimizing both the MLC leaf positions and the variable angular dose rate for IMAT delivery and compare single and multiple arc plans.
Sci‐Sat AM(1): Imaging‐07: Open field normalization: How to avoid inflation to MTF and DQE values caused by zero‐frequency normalization
Authors: Friedman SN , Cunningham IA
Published: July 2008

Purpose: To show that the novel open‐field normalization technique prevents a common error in calculation of the detective quantum efficiency (DQE) caused by zero‐frequency normalization of the modulation transfer function (MTF). Method and Materials: Models describing zero‐frequency and open‐field normalization were used to derive the resulting measured MTF, noise power spectrum (NPS) and DQE using a finite region of interest (ROI) of image data. Simulated one‐dimensional images containing Gaussian blur were used to model a deterministic system and to calculate the resultant values. Measurements were made using both zero‐frequency and open‐field normalization with ROIs ranging in size from 1–10 cm. Results: Use of a finite ROI results in truncation of the system line‐spread function (LSF) causing the zero‐frequency value of the measured MTF to be less than the true MTF value of unity, and causes spectral leakage in both the MTF and NPS. Zero‐frequency normalization of the MTF inflates values at all non‐zero frequencies. Since no zero‐frequency normalization is performed on the NPS, this causes inflated DQE values. Simulated results show a 6% inflation of DQE values for a ROI of 10 cm, which increases as the ROI is reduced. Open‐field normalization accurately determines MTF and NPS (and thus DQE) values at all frequencies away from zero frequency. Conclusion: Open‐field normalization measurements provide a good estimate of the true MTF and DQE. This approach should be used to avoid a common error in DQE calculations that is not obvious and inflates DQE calculations by 5–20%.
Sci‐Sat AM(2): Brachy‐01: A novel HDR Ir‐192 brachytherapy water calorimeter standard
Authors: Sarfehnia A , Seuntjens J
Published: July 2008

Parameters influencing the accuracy of absorbed dose measurements for HDR brachytherapy using water calorimetry were investigated with the goal to develop a novel primary absorbed dose to water standard. To provide greater stability, flexibility, and accuracy in the source‐detector distance dsrc‐det positioning and measurement, a new spring‐loaded catheter holder composed of two concentric cylindrical sleeves with multiple orthogonal adjusting screws was developed. The absorbed dose from Nucletron microSelectron‐HDR brachytherapy sources with air kerma strengths ranging between 21000–38000 U was studied. dsrc‐det is optimized so as to balance signal‐to‐noise ratio (decreasing with increasing dsrc‐det) and temperature drift effects resulting from source self‐heating. The irradiation times were adjusted to yield a minimum 1 Gy of dose at the measurement point. Successful measurements at dsrc‐det ranging between 25–50 mm were performed. COMSOL MULTIPHYSICS™ software was used to determine the heat loss correction due to conduction defined as the ratio between temperature rise at a point under ideal conditions to realistic conditions (i.e., no conduction). An agreement of better than 6.5% was observed between TG‐43 calculated and calorimetrically measured absorbed dose rates. The effects of convection where calculated to be negligible as the glass vessel provides a convective barrier significantly decoupling the water velocity in the interior and exterior of the vessel (water velocities were 1–2 orders of magnitude different). Our work paves the way to successful primary absorbed dose determination for radioactive sources using calorimetric techniques.
Essential tremor, deceptively simple …
Authors: Nahab Fatta B , Peckham Elizabeth , Hallett Mark
Published: July 2008

The diagnosis and management of essential tremor appears deceptively simple. However, isolated mild tremor may be difficult to classify, and if the patients have any additional features the diagnosis is more difficult. Management can be challenging, despite the numerous treatments available, because so many patients are not benefited adequately and some not at all. However, as we gain a better understanding of the disorder, more effective therapies with fewer adverse effects are sure to follow.
Ciguatera poisoning
Authors: Achaibar Kira C , Moore Simon , Bain Peter G
Published: July 2008

Ciguatera is a form of poisoning that occurs after eating tropical and subtropical ciguatoxic fish. The ciguatoxins are a family of heat stable, lipid soluble cyclic polyether compounds that bind to and open voltage-sensitive Na+channels at resting membrane potential, resulting in neural hyperexcitability, as well as swelling of the nodes of Ranvier. The authors describe a 45-year-old man who developed acute gastrointestinal symptoms in Antigua soon after eating red snapper and grouper, potentially “ciguatoxic fish”. This was followed by neurological symptoms 24–48 hours later, including temperature reversal (paradoxical dysaesthesia), intense pruritus and increased nociception as a result of a small fibre peripheral neuropathy. The patient’s symptoms and small fibre neuropathy improved over a period of 10 months.
Dementia with Lewy bodies and Parkinson’s disease with dementia: where two worlds collide
Authors: McKeith I
Published: July 2008

Parkinson’s disease and dementia with Lewy bodies are two common presentations of a single, underlying disease process (Lewy body disease) which is thought to be related to dysregulation of the synaptic protein, alpha-synuclein. This article discusses the nature of the relations between Parkinson’s disease and dementia with Lewy bodies, and what can be learned from them about the causes of dementia in patients with established Parkinson’s disease. This is an area of clinical practice which is of increasing importance as greater numbers of ageing patients survive longer with good treatment of their motor symptoms. Precise use of terminology and a clear understanding of the biological substrates underlying symptom formation are particularly helpful to both clinicians and patients.
Myelopathy but normal MRI: where next?
Authors: Wong S H , Boggild M , Enevoldson T P , Fletcher N A
Published: July 2008

For most patients presenting with a spinal cord syndrome MR scanning has become the key investigation in establishing the diagnosis. However, myelopathy with normal spinal imaging remains a common clinical conundrum. In this review we discuss the diagnoses to consider for the neurologist presented with a patient with “MR normal myelopathy”. We will illustrate this scenario with a series of short cases and consider the further investigation of “MRI normal” myelopathy.
Prognostic models
Authors: Rothwell P M
Published: July 2008

An appreciation of prognosis is essential for effective clinical practice, in neurology as in other fields. Predicting risk of a poor outcome in individuals, or at least in well-defined groups of individuals, is necessary to properly inform patients about what the future holds for them, and the likely benefits of treatment. Despite the various pitfalls in the derivation and validation of prognostic models (or scores), there are an increasing number of useful models available to help patients and clinicians in routine neurology practice. This article considers how such models are best derived, and how their reliability should be assessed, drawing on examples from various different neurological disorders.
Size-related changes in diel distribution of young grayling (Thymallus thymallus)
Authors: Sempeski P. , Gaudin P.
Published: July 2008

An approach based on direct observation from the riverbank allowed a precise description of the size-dependent distribution patterns of young grayling. The smallest larvae (15–20 mm) were mainly observed in the upper layers of the water column and very close to the riverbank. With increasing age and size (20–35 mm), old larvae and young parr began to hold positions closer to the bottom and to the edge of the main channel. From a size of 35–40 mm. an increasing number of juveniles were observed in the river channel, holding a benthic position. A diel habitat shift was also shown for individuals of all stages, between their respective daytime habitats and dead zones, where they were observed resting on the bottom in very shallow water at night. The benefits of this shift might be expressed in terms of energy conservation and (or) decreased predation risk. This study points out the importance of marginal habitats in the first weeks of grayling life as (i) exclusive nursery areas for larvae that use them both by day and by night and (ii) resting habitats for juveniles at night.
Temporal and environmental variation in the biomass spectrum of benthic invertebrates in streams: an application of thin-plate splines and relative warp analysis
Authors: Morin Antoine , Rodríguez Marco A. , Nadon Daniel
Published: July 2008

The size distribution of benthic invertebrates found on the surface of rocks was examined in 12 streams of the Ottawa Valley for 15 months. We used relative warp analysis and thin-plate splines to demonstrate that normalized biomass spectra were similar among sampling dates and among sites, although statistically significant seasonal patterns were detected. The relative abundance of the smallest organisms (mainly early instars of chironomid larvae between 0.1 and 1 mm long) varied the most and peaked in early summer in warm waters, leading to a reduction of the average size of invertebrates in early summer. Overall abundance also positively but weakly correlated with periphyton standing stock. Average size was larger in urban streams of Ottawa–Hull than in streams in cottage areas of the Outaouais or draining the protected forests of Gatineau Park, even after accounting for the effect of periphyton standing stock and concentration of total phosphorus. Total community production, estimated using the average size distribution in all sites and a published empirical model predicting instantaneous growth rate, peaked in early summer and reached a minimum in winter, following closely the seasonal water temperature pattern. The contribution of organisms smaller than 1 mm to total community production was only significant in early summer when it reached 20%.
Effect of age, growth rate, and ontogeny on the otolith size – fish size relationship in bluefish, Pomatomus saltatrix, and the implications for back-calculation of size in fish early life history stages
Authors: Hare Jonathan A. , Cowen Robert K.
Published: July 2008

The otolith size – fish size relationship was examined in field-collected larval and pelagic juvenile bluefish, Pomatomus saltatrix. The purpose was to evaluate the central assumption of proportional back-calculation techniques, namely that otolith and somatic growth are in constant proportion. Age-independent variability was found between otolith size and fish size that differed between ontogenetic stages. Stage-specific growth rate effects were also identified. Finally, the otolith size – fish size relationship changed at certain ontogenetic stage transitions. These effects, as well as others that have been found, are discussed with regard to the assumption of constant proportionality between otolith growth and fish growth. In light of this discussion, the overall validity of constant proportionality becomes suspect when applied to the early life history stages of fishes. Future work should take a longitudinal approach to the analysis of the relationship between otolith growth and somatic growth. In addition, regression and proportional methods should be modified to account for growth rate and ontogenetic effects. Finally, a relative size approach is presented that is appropriate in situations that require only relative measures of fish size. This relative size approach has several benefits and these are discussed in relation to other back-calculation procedures.
Wood density variability in successive breeding populations of maritime pine
Authors: Bouffier Laurent , Rozenberg Philippe , Raffin Annie , Kremer Antoine
Published: July 2008

Growth and form are the two main traits used for genetic improvement of maritime pine ( Pinus pinaster Ait.) in the southwest of France. In this paper, wood density is studied to answer two main questions: Is there a general trend for density variability throughout tree development and has selection indirectly reduced wood density variability over breeding populations, owing to genetic unfavourable correlation with growth? Wood density and its components were studied in three polycross tests, each representative of one of the successive breeding populations. Wood density was measured with an X-ray densitometer in approximately 50 families per test with >1900 trees. A preliminary study showed that bark-to-pith ring indexing allows for a better estimation of genetic effects than does pith-to-bark indexing. Genetic variability of wood density appears to be highly dependent on the year considered and no general pattern can be detected over time. Whereas the variability of selected traits is known to have decreased over breeding populations, no significant change was found for variability of wood density.
Fire history of pinyon–juniper woodlands at upper ecotones with ponderosa pine forests in Arizona and New Mexico
Authors: Huffman David W. , Fulé Peter Z. , Pearson Kristen M. , Crouse Joseph E.
Published: July 2008

We used maps of fire evidence, fire scar dendrochronology, forest age-structure analysis, and landscape analysis to investigate fire history at pinyon pine ( Pinus edulis Engelm.) – juniper ( Juniperus osteosperma (Torr.) Little, Juniperus scopulorum Sarg.) woodland – ponderosa pine ( Pinus ponderosa P. & C. Lawson) forest ecotones in Arizona (Tusayan) and in New Mexico (Canjilon). Results showed that charred trees were not evenly distributed across vegetative communities but were significantly (p < 0.001) more abundant than expected in ponderosa pine communities. Composite fire scar analysis indicated that surface fires occurred in ponderosa pine stands at both sites and burned at intervals of 7.2–11.1 years (WMPI; Weibull median probability interval). At Tusayan, landscape structure was fine grained, and maximum pinyon age was >200 years across 80% of the site. At Canjilon, landscape pattern was relatively coarse, and most pinyon patches were 200–300 years old. Cumulative standing age distributions suggested pinyon–juniper fire rotations of 340 and 290 years at Tusayan and Canjilon, respectively. We concluded the following: (i) surface fires in ponderosa pine stands did not spread through pinyon–juniper communities at either site, (ii) fire evidence was prevalent across both sites, but old pinyon trees indicated that no widespread lethal fires had occurred in the last 300–400 years, and (iii) structurally heterogeneous landscapes suggested that historical pinyon–juniper fires were of limited extent but lethal in patches.
What is the “END” (emulation of natural disturbance) in forest ecosystem management? An open question
Authors: Klenk Nicole , Bull Gary , Cohen Dave
Published: July 2008

The emulation of natural disturbance (END) is said to be the most promising avenue for implementing sustainable forest management; however, there appears to be no consensus as to the meaning of the END. We have interviewed forest scientists across Canada and, with the use of mental models and network textual analyses, created a shared mental model of the END. Results from both quantitative and qualitative analyses suggest that there are contrasting and contradictory views about the meaning of the END, which raise serious implications for the use of the END in policy making.
A line intersect distance sampling strategy for downed wood inventory
Authors: Affleck David L.R.
Published: July 2008

Perpendicular distance sampling (PDS) has emerged as a compelling alternative to line intersect sampling (LIS) for the inventory of forest fuels and other downed woody materials (DWM), particularly where the aggregate volume of DWM is of primary interest. This article develops a selection protocol and design-unbiased estimators for a new probability proportional-to-volume sampling strategy, termed line intersect distance sampling (LIDS). LIDS combines the distance sampling protocol of PDS with the transect sampling protocol of LIS and provides unbiased estimates of aggregate DWM volume from counts of selected logs or log fragments. Simulations indicate that LIDS along multidirectional (e.g., Y-shaped) transects should perform similarly to PDS in terms of sampling error; however, it remains unclear how LIDS and PDS compare with LIS, especially when interest is attached to multiple DWM population parameters. It is argued that LIDS will be most useful in reducing implementation errors, particularly detection errors, relative to PDS under limited visibility field conditions.
Seventy-seven years of natural disturbances in a mountain forest area — the influence of storm, snow, and insect damage analysed with a long-term time series
Authors: Hanewinkel Marc , Breidenbach Johannes , Neeff Till , Kublin Edgar
Published: July 2008

We investigated the effects of site properties, forest structure, and time on snow breakage, insect outbreaks, windthrow, and total damage for predominantly planted forests. A time series of forest damage in southwestern Germany spanning 77 years, from 1925 to 2001, was available along with a database on site properties and forest structure. The statistical modeling procedure successively addressed (i) probability of damage occurrence, (ii) timber loss in damaging events, and (iii) interaction among damage agents over time. Logistic and linear regressions were combined with multivariate autoregressive techniques. Natural disturbances were responsible for a total timber loss of 3.0 m3· ha–1· year–1. The distribution of the timber loss values over the years and over sites and stands with different properties was modeled with a standard error of 6.7 m3· ha–1· year–1. Disturbances are more likely to occur in previously damaged stands. Storm events typically provoke subsequent insect outbreaks between 2 and 6 years later. Large windthrow and snow breakage events tend to occur periodically, once every 10th, 11th, or 15th year. Analysis of disturbances as a time series significantly enhances understanding of forest risk processes.
Is early life cycle success a determinant of the abundance of red spruce and balsam fir?
Authors: Greenwood Michael S. , O’Brien Cristin L. , Schatz Jason D. , Diggins Corinne A. , Day Michael E. , Jacobson George L. , White Alan S. , Wagner Robert G.
Published: July 2008

Red spruce ( Picea rubens Sarg.) and balsam fir ( Abies balsamea (L.) Mill.) are sympatric in much of the Acadian Forest, but their relative regeneration success during the changing climates of the Holocene and after harvest in the modern forest has been distinctly different. Early life stage behavior may contribute to these differences. We report that seed germination by red spruce was equally fast and complete in warm and cool temperature regimes, while balsam fir germination was slower and less complete in both, especially the cool regime. Also, seedling shoot growth of red spruce exhibited a highly plastic response to increased light and water by maintaining continuous neoformed growth throughout the growing season, while balsam fir seedlings set bud after very little epicotyl development. Therefore, the root/shoot ratio of balsam fir was about twice that of red spruce, regardless of available light or water. Neoformed shoot growth under conditions of ample moisture and light would give red spruce a competitive advantage, but the relatively high root/shoot ratio of balsam fir seedlings would lower the likelihood that water and (or) mineral nutrients would limit shoot growth. The effects of these and other differences in life stage behavior on species abundance over time are discussed.
The effectiveness of signs at restricting vehicle traffic: a case of seasonal closures on forest access roads
Authors: Hunt Len M. , Hosegood Steven
Published: July 2008

We assessed the effectiveness of signs that temporally restrict vehicle traffic on forest access roads in northeastern Ontario. The signs specifically prohibit vehicle use of roads in proximity to lakes with remote (i.e., floatplane accessible) tourism during the first 2 weeks of the regular (i.e., rifles, shotguns, and muzzle-loaders) moose ( Alces alces ) hunting season. Vehicle use in restricted areas was measured by counts from traffic monitoring devices during the first 4 weeks of the hunting season (2 weeks during and 2 weeks after the restriction) at 14 sites with signs and another 14 sites without signs. The results suggest that these signs limit some, but not all, traffic in areas during the first 2 weeks of moose hunting. The estimated noncompliance rate with signs was 11.7% with a 95% confidence interval of 4.5% to 24.7%.
Age-Related Changes in Nutrient Utilization by Companion Animals
Authors: Fahey George C. , Barry Kathleen A. , Swanson Kelly S.
Published: July 2008

As companion animals age and pass through various life stages from in utero to the geriatric state, nutrient requirements change along with the manner in which nutrients are utilized by the various organ systems in the body. From the regulatory perspective, recognized life stages include maintenance, growth, and gestation/lactation. Other important life stages include in utero, the neonate, and the senior/geriatric state. Age affects digestive physiological properties, too, and factors such as gut microbiota, digestive hormones, gut morphology, gut immunity, and nutrient digestibility are modified as the animal becomes older. Each of the nutrients is affected in some manner by age, some more than others. Genomic biology offers promise in helping elucidate in greater detail how nutrient utilization is affected by age of the dog and cat.
SSR Locator: Tool for Simple Sequence Repeat Discovery Integrated with Primer Design and PCR Simulation
Authors: da Maia Luciano Carlos , Palmieri Dario Abel , de Souza Velci Queiroz , Kopp Mauricio Marini , de Carvalho Fernando Irajá Félix , Costa de Oliveira Antonio
Published: July 2008

Microsatellites or SSRs (simple sequence repeats) are ubiquitous short tandem duplications occurring in eukaryotic organisms. These sequences are among the best marker technologies applied in plant genetics and breeding. The abundant genomic, BAC, and EST sequences available in databases allow the survey regarding presence and location of SSR loci. Additional information concerning primer sequences is also the target of plant geneticists and breeders. In this paper, we describe a utility that integrates SSR searches, frequency of occurrence of motifs and arrangements, primer design, and PCR simulation against other databases. This simulation allows the performance of global alignments and identity and homology searches between different amplified sequences, that is, amplicons. In order to validate the tool functions, SSR discovery searches were performed in a database containing 28 469 nonredundant rice cDNA sequences.
Energy and Symmetry in Language and Yoga
Authors: Hess Sally , Napoli Donna Jo
Published: July 2008

The structures of syllables and of yoga poses are compared. Syllables are tripartite, with sound segments rising in sonority (acoustic energy) to a peak, then falling. Likewise, asanas are tripartite, with symmetrical movements flanking the sustaining, vital energy peak. In both entities, then, symmetric structure flanks energy peaks. This organization is not a physical necessity, but a cognitive preference.
Art in Its Experience: Can Empirical Psychology Help Assess Artistic Value?
Authors: Reber Rolf
Published: July 2008

This article outlines the roles of art theory and empirical psychology in understanding a work of art in its experience. Art theory sets the criteria of what the experience should be, and psychologists examine whether the predicted experience matches the observed experience of the recipient. An important issue is the role of knowledge in artistic evaluation, with resulting demand characteristics and concerns for self-presentation. With the help of recently developed implicit measures, both behavioral and biological, researchers are able to distinguish between explicitly reported knowledge and genuinely felt experience. The author presents examples of how art theory and empirical psychology might interact and how psychology can be used to examine a work's artistic value.
Using the Supercomputer to Visualize Higher Dimensions: An Artist's Contribution to Scientific Visualization
Authors: Cox Donna J.
Published: July 2008

The interdisciplinary research environment coupled with supercomputer graphics is affording new opportunities for collaborations between artists and scientists. The author has collaborated with specialists in such fields as agricultural entomology, topology and astrophysics to render visual representations of multidimensional computations. One collaboration has resulted in a single, aesthetic form encompassing both a new art form and the discovery of a suggested mathematical theorem. These team efforts provide interesting examples of research dynamics between artist and scientist as they work toward a common goal: visualization of the invisible. Such interaction serves as a prototype of the ‘Renaissance team’ where specialists provide a broad spectrum of skills in the quest for discovery. Artists can and will make important contributions to this research.
Music and Consciousness
Authors: Perlovsky Leonid
Published: July 2008

The author examines the crucial role that music plays in the evolution of consciousness.
Two Regimes of the Equatorial Warm Pool. Part II: Hybrid Coupled GCM Experiments
Authors: Watanabe Masahiro
Published: July 2008

In this second of a two-part study, the two regimes in a simple tropical climate model identified in Part I are verified using a hybrid coupled general circulation model (HCM) that can reproduce the observed climatology and the interannual variability reasonably well. Defining a ratio of basin width between the Pacific and Indian Oceans, a series of parameter sweep experiments was conducted with idealized tropical land geometry. Consistent with the simple model, the HCM simulates two distinct states: the split warm pool regime with large vacillation between the two ocean basins and the single warm pool regime representing current climate. The former is suddenly switched to the latter as the Pacific becomes wider than the Indian Ocean. Furthermore, the vacillation in the split regime reveals a preferred transition route that the warm phase in the Pacific follows that in the Indian Ocean. This route occurs due to convectively coupled Kelvin waves that accompany precipitation anomalies over land. Additional experiments show that the inclusion of the idealized Eurasian continent stabilizes the split regime by reducing the Bjerknes feedback in the Indian Ocean, suggesting the atmosphere–ocean–land interaction at work in maintaining the observed warm pool. No difference in cloud feedback was found between two regimes; this feature may, however, be model dependent.

Both the simple model and the HCM results suggest that the tropical atmosphere–ocean system inherently involves multiple solutions, which may have an implication on climate modeling as well as on the understanding of the observed mean climate.
Time-Expanded Sampling for Ensemble Kalman Filter: Assimilation Experiments with Simulated Radar Observations
Authors: Xu Qin , Lu Huijuan , Gao Shouting , Xue Ming , Tong Mingjing
Published: July 2008

A time-expanded sampling approach is proposed for the ensemble Kalman filter (EnKF). This approach samples a series of perturbed state vectors from each prediction run not only at the analysis time (as the conventional approach does) but also at other time levels in the vicinity of the analysis time. Since all the sampled state vectors are used to construct the ensemble, the number of required prediction runs can be much smaller than the ensemble size and this can reduce the computational cost. Since the sampling time interval can be adjusted to optimize the ensemble spread and enrich the ensemble structures, the proposed approach can improve the EnKF performance even though the number of prediction runs is greatly reduced. The potential merits of the time-expanded sampling approach are demonstrated by assimilation experiments with simulated radar observations for a supercell storm case.
The Influence of the El Niño–Southern Oscillation on Cloud-to-Ground Lightning Activity along the Gulf Coast. Part I: Lightning Climatology
Authors: LaJoie Mark , Laing Arlene
Published: July 2008

Cloud-to-ground (CG) lightning flashes from the National Lightning Detection Network are analyzed to determine if the El Niño–Southern Oscillation (ENSO) cycle influences lighting activity along the Gulf Coast region. First, an updated climatology of lightning was developed for the region. Flash density maps are constructed from an 8-yr dataset (1995–2002) and compared with past lightning climatologies. Second, lightning variability is compared with the phases of ENSO. Winter lightning distributions are compared with one published study of ENSO and lightning days in the Southeast.

Flash density patterns are, overall, consistent with past U.S. lightning climatology. However, the peak flash density for the annual mean was less than observed in previous climatologies, which could be due to the disproportionately large percentage of cool ENSO periods compared to previous lightning climatologies.

The highest annual lightning counts were observed in 1997, which consisted of mostly warm ENSO seasons; the 1997–98 El Niño was one of the strongest on record. The lowest lightning counts were observed in 2000, which had mostly cool or neutral phases of ENSO including the lowest Niño-3.4 anomaly of the study period. Analysis of winter season lightning flash densities substantiated the role of the ENSO cycle in winter season lightning fluctuations. Winter lightning activity increased dramatically during the 1997–98 El Niño. The lowest winter flash densities are associated with cool ENSO phases. Although 8 yr is inadequate to establish a long-term pattern, results indicate that ENSO influences lightning and that further study is warranted. As more years of lightning data are acquired, a more complete climatology can be developed.