bluuebunny/crossref_metadata_2025 huggingface dataset:
TH‐C‐217BCD‐03: Evaluation of the Spatial Resolution and Noise Properties of a Prototype Transmission Ultrasound Imaging System Employing an Acousto‐Optic (AO) Detector
Authors: Rosenfield JR , Sandhu JS , Tawiah JK , La Riviere PJ
Published: June 2012

Purpose: In this work, the spatial resolution and noise properties of a prototype full‐field transmission ultrasound imaging system employing an acousto‐optic (AO) liquid crystal detector were characterized. The AO effect is a phenomenon in which an incident acoustic wave field induces local birefringence changes in a liquid crystal. These birefringence changes manifest as brightness changes when the liquid crystal is optically illuminated using polarized light, thus providing spatial information about the field. Methods: A compressed, Zerdine‐based breast phantom containing 12 artificial spherical lesions was imaged using plane‐wave ultrasound illumination. Lesions of diameter 2 mm, 4 mm, 6 mm, and 8 mm were embedded at depths of 12.7 mm, 25.4 mm, and 38.1 mm within the phantom background. To minimize coherence artifacts, the transducer frequency was swept continuously from 3.25 MHz to 3.45 MHz at a rate of 100 MHz/s. The transducer voltage was ramped from 0.1 V to 6.5 V to permit identification of the onset of the AO effect in the detector. An analysis of image quality was performed on 50 identically acquired images in which the contrast‐to‐noise ratio was determined for each lesion in the mean acquired image. Apparent lesion size was also computed as a function of distance from the AO detector. Results: The spatial resolution analysis revealed that lesion size in the mean acquired image increased linearly with lesion‐to‐detector distance. Extrapolation of the least squares regression lines for apparent lesion size versus lesion‐to‐detector distance to zero distance agreed well with the actual lesion sizes. The noise analysis demonstrated that a contrast‐to‐noise ratio of 13.1 could be obtained with the prototype system for the transducer settings and phantom properties considered. Conclusions: This investigation indicates the potential for incorporating a liquid crystal AO detector into a transmission ultrasound system for full‐field breast imaging.
TH‐C‐217BCD‐04: 3D Ultrasound Reconstruction from Freehand Scans Using an Optical Tracking System
Authors: Samavati N , Vlad R , Tadayyon H , Moseley J , Iradji S , Czarnota G , Brock KK
Published: June 2012

Purpose: To develop a 3D‐ultrasound image reconstruction method from scans collected with a freehand 2D‐ultrasound probe and a tracking system affixed to the probe for coordinate determination. A freehand ultrasound probe can be used to obtain arbitrary volumes since the motion of the probe is unconstrained. However the 2D images are limited to a thin plane at an arbitrary angle in the volume of interest. The 3D‐ultrasound image reconstruction overcomes this limitation and allows accurate correlation with other 3D imaging modalities. Methods: A tracking system (Polaris Vicra system) which measures the 3D positions of markers affixed to the freehand ultrasound probe was used to determine the coordinates of the transducer during the scanning procedure. The tracking tool was calibrated to determine the location of each ultrasound imaging frame. This allowed the relative position of each ultrasound image plane to its neighboring images to be determined. The image intensities of the new 3D ultrasound volume were calculated by linear interpolation as the weighted average of the pixel values of nearest neighbors among the embedded 2D image intensities. Results: 3D ultrasound reconstructed volumes from freehand scanning of breast tumors clearly demonstrates the location and size of the tumor. The reconstruction accuracy was evaluated by comparing known inclusion volumes in a dedicated brachytherapy and breast ultrasound phantoms with the volumes obtained from the ultrasound reconstruction. The inclusions were contoured on each 2D slices obtained from the ultrasound reconstruction. The known volumes versus the measured volumes were (9.0/8.6 cc; 4.0/4.1cc; 0.27/0.25 cc) with an overall relative error of 5%. Conclusions: Accurate 3D ultrasound image reconstruction is possible using a tracker tool attached to the ultrasound freehand probe. The method offers the freedom of scanning large volumes of interest in breast and allows registration with other 3D imaging modalities. Terry Fox New Frontiers Program Project in Ultrasound for Cancer Therapy Dr. Brock has financial interest in deformable registration technology through the licensing of Morfeus to RaySearch Laboratories.
TH‐C‐217BCD‐05: Ultrasound Nakagami Imaging to Assess Breast Fibrosis Following Breast‐Cancer Radiotherapy
Authors: Yang X , Torres M , Chen H , Liu T
Published: June 2012

Purpose: To investigate ultrasound Nakagami imaging to assess breast fibrosis in women with breast cancer undergoing whole breast radiotherapy (RT). Methods: Previous studies have demonstrated that the Nakagami‐model‐based image can characterize scatterers in tissues through ultrasound echo statistics. We hypothesize that the Nakagami image may serve as a functional imaging tool to assess breast fibrosis. To test this concept, we conducted a pilot study with 10 breast‐cancer patients. All patients received a standard course of radiation: 50.4 Gy followed by an electron boost of 10.0 Gy at the lumpectomy site. A baseline ultrasound scan was performed one week prior to RT. Two additional scans were performed at 6‐month and 12‐month post RT. Patients were imaged on both breasts with a 10‐MHz ultrasound linear probe, in a supine position, at the 12, 3, 6, and 9 o'clock axes as well as at the lumpectomy site. Scans taken on the untreated breast served as a control. Conventional ultrasound images and radio‐frequency (RF) echo signals were acquired simultaneously. The envelopes of backscattered radio‐frequency signals were used for Nakagami imaging. The Nakagami parameter image is constructed by using a square sliding window to process the enveloped signals. Results: Significant changes were observed in Nakagami image parameter values between the treated and untreated breasts. The average Nakagami parameters was 1.02 for the untreated breasts and 1.18 for treated breasts (p<0.001). The increased Nakagami parameter indicates increase in the concentration of local scatterers and the appearance of the periodic structures or clustering of scatterers that would change the backscattering statistics. Such changes may be correlated to the development of fibrosis. Conclusions: The current findings indicate that the ultrasound Nakagami image has great potential as a functional imaging tool to complement the use of the conventional B‐scan to assess radiation‐induced breast fibrosis.
TH‐C‐217BCD‐07: Ultrasound Contrast Agents as Facilitator for Intracellular Transport of Drugs and Genes
Authors: Deng C
Published: June 2012

Purpose: The non‐invasive feature of ultrasound applications and the unique capability of ultrasound interaction with biological systems offer a beneficial platform for innovative biomedical applications. The effective and concentrated nature of ultrasound interaction with gaseous particles, has prompted the development of microbubble‐based ultrasound contrast agents to enhance ultrasound imaging capability. Particularly, microbubble ultrasound contrast agents have been exploited as a vehicle for intracellular delivery of cell impermeant drugs and genes. Ultrasound excitation of microbubbles, accompanied by rapid radial oscillation and/or collapse, has shown promise as an advantageous non‐viral strategy to generate transient increase of cell membrane permeability (sonoporation), thereby allowing uptake of exogenous agents into the cell cytoplasm. However, little is known about the basic processes supporting ultrasound‐induced transport into and within the cytoplasm of living cells at the single cell level. Our research aims to gain understanding of the mechanism of sonoporation and to uncover the physical, chemical, and cellular factors affecting the sonoporation process and outcome, in order to successfully develop and translate sonoporation technology for targeted, safe delivery of drugs and genes. Methods: We developed a set of novel techniques to control microbubble cavitation in reference to single cells. We used simultaneous whole‐cell patch clamp recording and fluorescence microscopy for real time monitoring of sonoporation. Results: We obtained measurements regarding the rapid formation and resealing of ultrasound‐induced membrane pores. Based on sonoporation‐mediated influx of an intercalating fluorescent dye, we developed a model to measure the intracellular diffusion coefficient of cytoplasmic RNA/DNA and estimate the pore size generated during sonoporation. We demonstrated spatiotemporally controlled subcellular delivery and calcium signaling in targeted cells. Conclusion: Through controlling of ultrasound excitation of microbubbles near single cells, we obtained results that might reveal key information of sonoporation mechanisms and processes, that can guide the development of sonoporation at as an effective and robust delivery technology.
TH‐C‐218‐01: How to Implement an IGRT and SBRT with Siemens Linacs and the Brainlab ExacTrac System
Authors: Mihailidis D
Published: June 2012

Image guided stereotactic radiotherapy is a treatment modality that combines a variety of new technologies from imaging, to treatment planning and treatment delivery. It has been the primary method of treatment for several cranial and extra cranial tumors, where accurate patient immobilization and setup, tumor delineation, complex treatment planning and pre‐treatment imaging, are necessary for accurate treatment delivery. Typically, the coverage of the topic has been for a single‐technology, single‐vendor system, for example, MVCBCT by Siemens was presented, against kVCBCT by Elekta and Varian or MVCT by Tomotherapy, all for IG and/or SBRT purposes. The clinical reality many times is far from single‐vendor technology. Many medium and small size clinics upgrade their delivery systems (linacs) for IG and SBRT by add‐ons coming from multiple vendors. As an example, a Siemens linac with Brainlab Exactrac IG system and third party treatment planning system, all put together to provide IG and SBRT programs within the clinical environment. Users find themselves up against issues that are not necessarily addressed by a course that describes a closed single‐vendor IG/SBRT systems, like a Novalis TX with i‐plan or Tomotherapy or Cyberknife or others. This presentation will outline the main issues and give a step‐by‐step method for clinical implementation of all the components in order to achieve the final goal. Points of caution for the user, limitations and financial considerations will be part of the presentation.

Learning objectives:

1. To gain insight into the issues that come up when technologies from various vendors are combined towards an integrated IG and/or SBRT program.

2. To understand the step‐by‐step method of integration of the involved technologies towards their clinical implementation.

3. To develop the understanding of the importance of benchmarking of IG and SBRT programs and usefulness of end‐to‐end testing.

4. To develop the ability to deal with the technical limitations of the technologies chosen to be implemented in the clinic.
TH‐C‐218‐03: IGRT in Prostate Cancer: The Calypso 4D Localization System
Authors: Djemil T
Published: June 2012

There is mounting evidence that for prostate cancer patients treated with EBRT, dose escalation to the prostate increases local control. This benefit comes at the cost of toxicities and complications. Therefore, restricting the dose to normal tissue becomes of utmost importance. Image guidance for accurate treatment delivery and intra‐fraction motion monitoring is critical in this environment of dose escalation and hypo fractionation.A variety of systems could be utilized for this purpose, such as transabdominal ultrasound, KV X‐rays, and KV/MV CBCT. However, these systems have several disadvantages: they only provide snapshots of the prostate position; they are not available during radiation delivery; they cause an additional ionizing radiation exposure; and they may be subjective and operator dependant in acquisition and interpretation. A newer technology using non ionizing electromagnetic field and implanted fiducial markers (transponders) to locate and track patient tumors is available by Calypso Medical. In this presentation, our experience with IMRT and SBRT prostate treatments at the Cleveland Clinic will be presented. The treatment plans are generated with the Pinnacle treatment planning system, the localization and tracking is performed by the 4D Calypso system, and the treatment delivery is done on an Elekta Synergy S linac.

Learning Objectives:

1. Understand the clinical rationale for localization and tracking

2. Understand the necessity of hybrid technologies and systems

3. Understand the physics behind the Calypso localization mechanism and its principles of operation

4. Understand operational and quality assurance aspects of Calypso combined with Synergy‐S and Pinnacle TPS

5. Understand the technical limitations of the hybrid system

6. Describe clinical implementation of the system and typical cases treated
TH‐E‐211‐01: Economics of Light Ion Teletherapy
Authors: Moyers M
Published: June 2012

Treatment of patients with beams of light ions (including protons) began in 1954. Despite the dosimetric advantages of these beams, 58 years later less than 1% of patients treated with radiation in the United States currently receive light ion teletherapy. This is primarily due to the large initial investment needed to construct light ion facilities. This course will provide the audience with example estimates of equipment, construction, maintenance, and salary costs along with projections of estimated reimbursement over the lifetime of the equipment. Comparisons of individual project costs will be given to demonstrate which items have the most impact on project success. Several example methods for reducing both the operating costs and initial costs will be presented including a brief discussion of new technology. Some cost reduction measures, however, can result in decreased performance which may affect the patient population that may be treated. Several cost/performance tradeoff examples will bepresented.

Learning Objectives:

1. Become familiar with estimated costs associated with starting and operating a light ion teletherapy facility.

2. Become familiar with the relative costs of various items important for the success of a project.

3. Become familiar with tradeoffs in performance for various cost saving methods.
TH‐E‐BRCD‐03: Automatic Treatment Planning for IMRT, VMAT and IMPT
Authors: Zhang X
Published: June 2012

In intensity‐modulated radiotherapy (IMRT), including intensity modulated X‐ray therapy (IMXT), volumetric modulated arc therapy (VMAT) and intensity modulated proton therapy (IMPT), the quality of the treatment plan, which is highly dependent upon the treatment planner's level of experience, greatly affects the potential benefits of the radiotherapy (RT). Furthermore, the planning process is complicated and requires a great deal of iteration, and it is often the most time‐consuming aspect of the RT process. There is also a long learning curve to design the “optimal” plan for the newest technology such as IMPT. However, recent optimization algorithm technology development, especially automatically planning based on some kind of machine learning, have reached a point in treatment planning process where treatment plan can be designed without or with minimum human intervention. In this work, we describe the methodology and validation results of mdaccAutoPlan system: this system has the potential to automate IMXT/VMAT/IMPT treatment planning to the extent that human intervention is minimal. For every new patient, the mdaccAutoPlan system could automatically generate plans (the autoplans) that meet or exceed the institution's dose‐volume constraints by one button click in the TPS. The methodology 1) automatically sets beam angles based on a data mining of previously plans designed by experienced dosimetristsand a beam angle automation algorithm, 2) judiciously designs the planning structures, which were shown to be effective for all the patient cases we studied, and 3) automatically adjusts the objectives of the objective function based on a parameter automation algorithm. We compared treatment plans created in this system (mdaccAutoPlan) based on the overall methodology with plans from the plans created by the experienced dosimetrists. The “autoplans” were consistently better, or no worse, than the plans produced by experienced medical dosimetrists in terms of tumor coverage and normal tissue sparing. This lecture will provide an overview of overall methodology in the “autoplan” system and its validation on the treatment planning process in IMRT, VMAT, IMPT and adaptive radiotherapy planning (ART).

Learning Objectives:

1. Understand the bottleneck of current inverse planning and evaluation process

2. Understand the importance of data mining of pre‐existing treatment plans

3. Understand the impact of automation on reducing the learning curve of new technologies

4. Understand the importance of automatic planning on improving quality and consistence of radiation therapy

5. Understand the clinical workflow of automatic planning
TH‐A‐BRA‐11: Treatment‐Induced Dosimetric/Volume Changes During the Course of Radiotherapy for Lung Cancer
Authors: Chung Yi Hsuan , Kelsey Christopher , Das Shiva
Published: June 2012

Purpose: To investigate the necessity for adaptive radiation therapy (RT) in lung cancer IMRT treatments by quantifying tumor changes during radiotherapy and the associated impact on target, lung and esophagus. Methods: As part of an IRB‐approved lung dose escalation study, contrasted CT scans were acquired on 15 patients prior to RT and in the 2nd and 5th week of treatment (total dose=58–70 Gy, 2Gy/fraction). Target, lung and esophagus volumes were segmented in all CT datasets. The original plan was recomputed on the subsequent CT sets and doses were accumulated by deformable registration to approximate the actual delivery. Five patients with the largest tumor shrinkage were selected and re‐planned on the 2nd and 5th week CT sets. The plans were summed to mimic adaptive radiation therapy. Comparisons were made between the approximated actual treatment, summation of the re‐optimized plans, and the original plan. Comparison metrics included QUANTEC dose parameters, equivalent uniform dose (EUD), maximum dose and target coverage (unless otherwise stated, all percentage changes in results are with respect to the original plan, averaged over all patients). Results: The approximated actual delivery had significantly increased lung dose‐ volume/EUD (V5 =8.19%, V20 = 4.14%, EUD = 5.95%). Tumor shrinkage‐ induced esophageal volume outside the originally segmented volume (3.4%–101.8%) was significant. Elevated esophagus EUD (7.27%) and spinal cord maximum dose (6.7%) were observed in most patients. PTV/GTV volumes receiving 100% of prescription dose decreased (week 2/5 PTV = −10.0%/‐ 6.88%, week 2/5 GTV = ‐6.7%/−4.1%), along with slightly increased dose to the highest 1 % of volume. Compared to the approximated actual delivery, re‐optimized plans overall showed superiority in lowered dose to the esophagus (V35=−40.32%, EUD =−13.42%), lungs (V5=−4.18%, V20=− 10.66%) and spinal cord (Dmax=−22.98%). Conclusions: RT‐induced esophageal volume displacement and increased lung dose during treatment are significant, warranting re‐plan in cases where large tumor changes are expected.
TH‐A‐213CD‐08: Spectrography Using a Marchesini Algorithm
Authors: Yu H , Wang G
Published: June 2012

Purpose: Recently, ‘ankylography’ was proposed to perform a 3D reconstruction from a single exposure of a monochromatic radiation beam. This approach was very attractive to reveal structures such as complex proteins that can be glimpsed only once before they are destroyed by the high‐intensity beam. However, the solution is neither unique nor stable in general. The purpose of this work is to solve that problem from one or two spectral views, which is referred to as ‘spectrography’. Methods: In contrast to ‘ankylography’, we acquire polychromatic diffractive views with energysensitive detectors. For example, a spectrographic system may consist of two spectral imaging chains perpendicular to each other. As a result, sufficiently many Ewald spheres can be simultaneously measured in the Fourier space for 3D reconstruction. To evaluate the performance of spectrography, the hybrid input‐output algorithm is implemented for phase retrieval and improved with a subspace saddle‐point optimization technique proposed by Marchesini. Results: A 32X32X32 Shepp‐Logan phantom (symmetric with respect to the z axis) is employed to demonstrate the feasibility of the proposed spectrography scheme. Extensive numerical tests are conducted in different configurations and have produced promising results. When the radiation waves span an infinite spectrum, exact results can be reconstructed without any additional constraint. When the spectrum becomes narrower, the solution becomes gradually less stable. Conclusions: Spectrography overcomes the non‐uniqueness and instability of ‘ankylography’. This approach has an ultrafast imaging speed for potential applications such as drug designs.
An Overlapping Protein-Coding Region in Influenza A Virus Segment 3 Modulates the Host Response
Authors: Jagger B. W. , Wise H. M. , Kash J. C. , Walters K.-A. , Wills N. M. , Xiao Y.-L. , Dunfee R. L. , Schwartzman L. M. , Ozinsky A. , Bell G. L. , Dalton R. M. , Lo A. , Efstathiou S. , Atkins J. F. , Firth A. E. , Taubenberger J. K. , Digard P.
Published: June 2012

Influenza's Cryptic Constraint

Because of the well-known pandemic potential of influenza viruses, it is important to understand the range of molecular interactions between the virus and its host. Despite years of intensive research on the virus,

Jagger
et al.

(p.
199
, published online 28 June; see the Perspective by

Yewdell and Ince

) have found that the influenza A virus has been hiding a gene in its small negative-sense RNA genome. An overlapping open reading frame was found contained in the PA viral RNA polymerase gene, which is accessed by ribosomal frameshifting to produce a fusion protein containing the N-terminal messenger RNA (mRNA) endonuclease domain of PA and an alternative C-terminal X domain. The resulting polypeptide, PA-X, selectively degrades host mRNAs and, in a mouse model of infection, modulated cellular immune responses, thus limiting viral pathogenesis.
Immediate Effects of Acupuncture and Cryotherapy on Quadriceps Motoneuron Pool Excitability: Randomised Trial Using Anterior Knee Infusion Model
Authors: Park Jihong , Ty Hopkins J
Published: June 2012

Objective

The authors asked the following research questions: will an anterior knee infusion model induce constant pain? will perceived pain alter motoneuron pool (MNP) excitability? and will treatments alter perceived pain and/or MNP excitability?

Methods

Thirty-six neurologically healthy volunteers participated in this randomised controlled laboratory study. To induce anterior knee pain (AKP), 5% hypertonic saline (0.12 ml/min with a total volume of 8.5 ml over 70 min) was injected into the infrapatellar fat pad of the dominant leg. One of four 30-min treatments was randomly assigned to each subject after pain was induced (acupuncture, cryotherapy, sham cryotherapy and no treatment). Five acupuncture needles (SP9, SP10, ST36, GB34 and an ah shi point) were inserted to a depth of 1 cm. Vastus medialis (VM) maximum Hoffmann reflexes normalised by maximum motor response were recorded from each subject at baseline, 20 min post-injection, 50 min post-injection and 70 min post-injection. To record pain perception, a visual analogue scale was used every 5 min after injection.

Results

An anterior knee infusion pain model increased perceived pain (p<0.0001). No change was found in VM MNP excitability among the four treatments (p<0.19) or at any of the time intervals (p<0.52). Cryotherapy reduced perceived pain compared with acupuncture (p=0.0003) and sham treatment (p=0.0002).

Conclusions

A pain model may be used in other neurophysiological intervention studies related to AKP. AKP alone may not directly alter quadriceps activation. None of the treatments altered VM MNP excitability. Cryotherapy reduced pain while a single session of acupuncture and sham treatments did not.
Kallmann syndrome in a female adolescent: a new mutation in the FGFR1 gene
Authors: Novo Ana , Guerra Isabel Couto , Rocha Felisbela , Gama-de-Sousa Susana , Borges Teresa , Cerqueira Rita , Tavares Purificação , Fonseca Paula
Published: June 2012

The Kallmann syndrome is characterised by the association of hypogonadotropic hypogonadism and hypo/anosmia. It represents a phenotypically and genotypically heterogeneous clinical entity, with six genes identified so far in the literature—KAL1, FGFR1, PROKR2, PROK2, CHD7 and FGF8. Mutations in the FGFR1 gene can be found in approximately 10% of the patients. The authors present the case of a female adolescent with hypogonadotropic hypogonadism and impaired olfactory acuity in the presence of hypoplasia of the nasal sulcus and agenesis of the olfactory bulbs. The molecular analysis of the fibroblast growth factor receptor 1 identified a heterozygous mutation c.1377_78insA (p.V460SfsX3) in exon 10 of FGFR1 gene. This mutation has not yet been reported in the literature. A theoretical review of clinical features and therapeutic approach of this syndrome is also presented.
A pituitary abscess masquerading as recurrent hypernatremia and aseptic meningitis: Figure 1
Authors: Gonzales Michael , Marik Paul Ellis , Khardori Romesh K , O'Brian John T
Published: June 2012

Pituitary abscess is a rare condition. In the setting of multiple surgical interventions, the risk of its development increases. A 49-year-old man presented with episodes of altered mental status. He had two surgeries for a recurrent suprasellar arachnoid cyst. The second surgery was complicated by a persistent cerebrospinal fluid (CSF) leak that required two repairs following which he developed panhypopituitarism and central diabetes insipidus. Twelve months after his last surgery he was diagnosed with aseptic meningitis. This was followed by recurrent hospitalisations for severe hypernatremia blamed on poor medication compliance. He was subsequently hospitalised for the evaluation of a febrile illness. Brain MRI showed ventriculitis and enhancement of the sella. Exploratory surgery revealed a purulent collection in the sella and a mucosal graft which had been used to repair the CSF leak. After drainage of pus and replacement of the graft he recovered completely but requiring life-long hormonal replacement.
Secondary production as a tool for better understanding of aquatic ecosystems
Authors: Dolbeth M. , Cusson M. , Sousa R. , Pardal M.A.
Published: June 2012

A major challenge for ecologists is understanding ecosystem dynamics and function under environmental and anthropogenic stresses. An approach for addressing this challenge is the analysis of the different components contributing to secondary production (i.e., consumer incorporation of organic matter or energy per time unit) and how this production is influenced by external factors. Production studies have been recognized as a powerful tool in aquatic ecology, with applications in energy–biomass flow studies, trophic ecology, management of biological resources, as well as assessment of environmental stress. In this paper, we summarize ideas and techniques related to the estimation of secondary production and discuss how this approach may be used to evaluate ecological change in aquatic ecosystems. We include a critical review of classical methods and empirical models to estimate secondary production and provide several applications of production studies to current stresses affecting aquatic ecosystems, such as climate change, pollution, and the introduction of non-indigenous invasive species. Our goal is to illustrate the advantages of using secondary production as a more integrative tool for the assessment of the ecosystem function, in particular when subjected to strong anthropogenic and climatic stress.
Evaluating fish diet analysis methods by individual-based modelling
Authors: Ahlbeck Ida , Hansson Sture , Hjerne Olle
Published: June 2012

Knowledge of diet compositions is important in ecological research. There are many methods available and numerous aspects of diet composition. Here we used modelling to evaluate how well different diet analysis methods describe the “true” diet of fish, expressed in mass percentages. The methods studied were both basic methods (frequency of occurrence, dominance, numeric, mass, points) and composite indices (Index of Relative Importance, Comparative Feeding Index). Analyses were based on both averaged stomach content of individual fish and on pooled content from several fish. Prey preference, prey size, and evacuation rate influenced the performance of the diet analysis methods. The basic methods performed better than composite indices. Mass and points methods produced diet compositions most similar to the true diet and were also most robust, indicating that these methods should be used to describe energetic–nutritional sources of fish.
The impact of an invasive predator (Orconectes rusticus) on freshwater snail communities: insights on habitat-specific effects from a multilake long-term study
Authors: Kreps Timothy A. , Baldridge Ashley K. , Lodge David M.
Published: June 2012

Most studies of the impacts of invasive species are done at small spatial and short temporal scales, greatly limiting generalizations to natural ecosystems. In contrast, we examined the long-term, whole-lake impacts of predation by the introduced rusty crayfish ( Orconectes rusticus ) on snail communities in 10 lakes in northern Wisconsin, USA. In 1987 and 2002, crayfish and snails were surveyed in lakes that initially differed in O. rusticus abundance; during the 15 years between surveys, crayfish abundance changed substantially in four lakes. In the two lakes where O. rusticus populations increased from low to high densities, large reductions occurred in snail abundance. As predicted, snails declined much more in habitats preferred by O. rusticus (sand and cobble) than in habitats that are avoided by the crayfish (muck). In the two lakes where O. rusticus abundance decreased dramatically after 1987, no significant increase occurred in snail densities, illustrating the difference in response time of snail populations to release from predation relative to increasing predation. Contrary to prediction, no consistent difference in snail species composition existed between high and low crayfish density lakes.
Local- versus landscape-scale effects on the demography of three forest-breeding songbirds in Ontario, Canada
Authors: Richmond S. , Nol E. , Burke D.
Published: June 2012

Reproductive success of songbirds breeding in forest fragments can be influenced by local habitat characteristics and by anthropogenic land uses in the surrounding matrix such as exurban development and agriculture. Effectively managing these songbirds requires an understanding of which spatial scales most strongly influence their demography. We conducted a multiscale study to investigate the relative influence of local vegetation characteristics and landscape composition at two spatial scales (100 and 2000 m) in a predominantly agricultural landscape on songbird demography. Density, pairing success, nest success, and productivity were assessed for Ovenbirds ( Seiurus aurocapilla (L., 1766)), Wood Thrush ( Hylocichla mustelina (J.F. Gmelin, 1789)), and American Robins ( Turdus migratorius L., 1766) in 16 deciduous forest fragments in southeastern Ontario. Demography of Ovenbirds was most strongly associated with local vegetation characteristics, while demography of Wood Thrush and American Robins was most strongly related to landscape composition within a 2000 m buffer. For all three species, cross-scale correlations influenced nest success, although other demographic parameters were less affected. We conclude that relationships between local- and landscape-scale metrics and songbird demography are complex, species-specific, and differ among reproductive parameters, necessitating a multiscale approach to management.
Distribution of pair quality in a tree-nesting waterbird colony: central-periphery model vs. satellite model
Authors: Minias Piotr , Kaczmarek Krzysztof , Janiszewski Tomasz
Published: June 2012

The spatial distribution of pair quality within waterbird colonies has been suggested to follow one of three theoretical models: central-periphery, satellite, or random. The central-periphery pattern occurs in homogeneous habitats, where good-quality pairs occupy better protected, central nesting sites. In contrast, the satellite and random patterns are associated with heterogeneous habitats and they assume that good-quality pairs occupy the most attractive nesting sites irrespectively of their location within the colony. Spatial patterns of laying date, clutch size, and fledging success were analysed with geostatistical tools in the colony of tree-nesting subspecies of Great Cormorant ( Phalacrocorax carbo sinensis (Blumenbach, 1798)) in central Poland. There was support for the random or satellite model in the distribution of clutch size, which was considered a reliable proxy of pair quality. We also found a positive correlation of clutch size with nest height. These results implicate that the habitat of tree-nesting colonial waterbirds may produce sufficient variation in the nesting-site quality to disrupt the central-periphery gradients of pair-quality distribution. In contrast, distribution of fledging success within the colony followed a clear central-periphery pattern, which was suggested to reflect an increased predation rate at the edges of the colony, rather than the intrinsic quality of breeding birds.
Dispersing Siberian flying squirrels (Pteromys volans) locate preferred habitats in fragmented landscapes
Authors: Selonen V. , Hanski I.K.
Published: June 2012

In fragmented landscapes, dispersal abilities determine the potential of a species to colonize temporally unoccupied habitats. For example in territorial species, even the high-quality sites will be temporally unoccupied between the death of residents and recolonization by dispersers. This has implications for conservation management, because whether or not unoccupied habitats are worthy of protecting depends on likelihood that these sites will be recolonized in the near future. We analysed the ability of dispersing Siberian flying squirrels ( Pteromys volans (L., 1758)) to locate the preferred habitats. Dispersers encountered many patches of preferred habitat and, in the end, a majority of them successfully settled in these patches. The dispersal distance increased with increasing distance between patches, but settlement in preferred patches and short-term mortality were independent of dispersal distance or distance between available patches. We conclude that dispersers were effective in locating the preferred habitat in fragmented landscapes. Indeed, large interpatch distances partly explain that dispersal distances are longer in flying squirrels than usually observed in similar-sized mammals. For conservation management, our findings encourage managers to protect temporally unoccupied, high-quality habitats in addition to occupied habitats to promote a sustainable habitat network in space and time.
POLYNOMIAL HULLS AND ENVELOPES OF HOLOMORPHY OF SUBSETS OF STRICTLY PSEUDOCONVEX BOUNDARIES
Authors: NOBEL LENNART
Published: June 2012

First we give a construction of a Cantor set in the unit sphere in ℂ3 the polynomial hull of which contains interior points. Such sets were known to exist in spheres in ℂ2. Secondly, we construct an open connected subset of the unit sphere in ℂ3 with infinitely sheeted envelope of holomorphy.
RECENT DEVELOPMENTS ON 3D INTEGRATION OF METALLIC SET ONTO CMOS PROCESS FOR MEMORY APPLICATION
Authors: JOUVET N. , BOUNOUAR M. A. , ECOFFEY S. , NAUENHEIM C. , BEAUMONT A. , MONFRAY S. , RUEDIGER A. , CALMON F. , SOUIFI A. , DROUIN D.
Published: June 2012

This work presents a nanodamascene process for a CMOS back-end-of-line fabrication of metallic single electron transistor(SET), together with the use of simulation tools for the development of a SET SRAM memory cell. We show room temperature electrical characterizations of SETs fabricated on CMOS with relaxed dimensions, and simulations of a SET SRAM memory cell. Using their physical characteristics achievable through the use of atomic layer deposition, it will be demonstrated that it has the potential to operate at temperature up to 398 K, and that power consumption is less than that of equivalent circuit in advanced CMOS technologies. In order to take advantage of both low power SETs and high CMOS drive efficiency, a hybrid 3D SET CMOS circuit is proposed.
EFFECT OF VERTICAL MECHANICAL COMPRESSION ON THE RESISTIVE SWITCHING CURRENTS OF TITANIUM DIOXIDE THIN FILMS
Authors: MORETTI MATHIEU , NICKLAUS MISCHA , NAUENHEIM CHRISTIAN , RUEDIGER ANDREAS
Published: June 2012

We report on a scanning probe investigation of the resistive switching behavior of TiO2 thin films as a function of an external bias voltage. Our initial conductive atomic force microscopy scans (c-AFM) on 30 nm thick films of sputtered TiO2 confirm the Ron–Roff ratio of approximately 4:1 reported in literature. After a tapping mode scan that compacts this layer by approximately 3%, a subsequent c-AFM scan reveals that the resistance in the compacted region has increased by a factor of 40 while the Ron–Roff ratio is only affected for small bias voltages.
AN ENTROPIC PICTURE OF EMERGENT QUANTUM MECHANICS
Authors: ACOSTA D. , FERNÁNDEZ DE CÓRDOBA P. , ISIDRO J. M. , SANTANDER J. L. G.
Published: June 2012

Quantum mechanics emerges à la Verlinde from a foliation of ℝ3by holographic screens, when regarding the latter as entropy reservoirs that a particle can exchange entropy with. This entropy is quantized in units of Boltzmann's constant kB. The holographic screens can be treated thermodynamically as stretched membranes. On that side of a holographic screen where spacetime has already emerged, the energy representation of thermodynamics gives rise to the usual quantum mechanics. A knowledge of the different surface densities of entropy flow across all screens is equivalent to a knowledge of the quantum-mechanical wavefunction on ℝ3. The entropy representation of thermodynamics, as applied to a screen, can be used to describe quantum mechanics in the absence of spacetime, that is, quantum mechanics beyond a holographic screen, where spacetime has not yet emerged. Our approach can be regarded as a formal derivation of Planck's constant ℏ from Boltzmann's constant kB.
Possibility of Exciton Mediated Superconductivity in Nano-Sized Sn/Si Core–Shell Clusters: A Process Technology towards Heterogeneous Material in Nano-Scale
Authors: Kurokawa Yuichiro , Hihara Takehiko , Ichinose Ikuo , Sumiyama Kenji
Published: June 2012

We have produced Sn/Si core–shell cluster assemblies by a plasma-gas-condensation cluster beam deposition apparatus. For the sample with Si content = 12 at. %, the temperature dependence of electrical resistivity exhibits a metallic behavior above 10 K and the onset of superconducting transition below 6.1 K. With decreasing temperature, the thermomagnetic curve for the sample with Si content = 8 at. % begins to decrease steadily toward negative value below 7.7 K, indicating the Meissner effect. An increase in the transition temperature, T
C is attributable to exciton-type superconductivity.
Internal Quantum Efficiency and Nonradiative Recombination Rate in InGaN-Based Near-Ultraviolet Light-Emitting Diodes
Authors: Kohno Takakazu , Sudo Yasuhiro , Yamauchi Masaki , Mitsui Kazuya , Kudo Hiromitsu , Okagawa Hiroaki , Yamada Yoichi
Published: June 2012

The internal quantum efficiency (IQE) of three types of InGaN-based near-UV light-emitting diodes (LEDs) grown on different substrates was studied by excitation-power-density-dependent and temperature-dependent photoluminescence (PL) spectroscopy. IQE was evaluated under both the band-to-band excitation of GaN cladding layers and the selective excitation of InGaN active layers. A correlation between IQE and threading dislocation density was clearly observed under both excitation conditions. In addition, the dynamics of radiative and nonradiative recombinations was studied by time-resolved PL spectroscopy. The rate of nonradiative recombination was evaluated by measuring temperature-dependent nonradiative recombination lifetime. The validity of our method for estimating IQE is discussed on the basis of the correlation between IQE and nonradiative recombination rate for three LEDs with different threading dislocation densities.
Asymmetrically Doped GaAs/AlGaAs Double-Quantum-Well Structure for Voltage-Tunable Infrared Detection
Authors: Choi Jae Kyu , Vagidov Nizami , Sergeev Andrei , Kalchmair Stefan , Strasser Gottfried , Vasko Fedir , Mitin Vladimir
Published: June 2012

We fabricate, characterize, and analyze tunable mid-infrared photodetectors based on asymmetrically doped coupled quantum well GaAs/AlGaAs structures. The peak of photoresponse detection varies from 7.5 to 11.1 µm when switching bias from -5 to +5 V. The spectral tunability is defined by the interplay of several effects. First, the electron energy levels are shifted due to the Stark effect. Second, the applied electric field causes the charge redistribution in the coupled wells and shift of electron energy levels due to modification of self-consistent potential. Here we show that effect of electric field on tunneling processes (the Poole–Frenkel effect) and the field-induced decrease of thermo-emission barrier (the Fowler–Nordheim effect) also play a critical role in photoelectron kinetics, strongly enhancing the carrier extraction from quantum wells. The model which takes into account Poole–Frenkel and Fowler–Nordheim effects provides a quantitative description of the data obtained.
Evaluation of Crystal Orientation for (K,Na)NbO3 Films Using X-ray Diffraction Reciprocal Space Map and Relationship between Crystal Orientation and Piezoelectric Coefficient
Authors: Shibata Kenji , Suenaga Kazufumi , Watanabe Kazutoshi , Horikiri Fumimasa , Mishima Tomoyoshi , Shiratani Masaharu
Published: June 2012

We have found an effective method for the evaluation of the crystal orientation of (K,Na)NbO3 (KNN) films in the (K,Na)NbO3/Pt/Ti/SiO2/Si structure using X-ray diffraction (XRD) reciprocal space maps. Previously, the crystal structure and orientation of such (K,Na)NbO3 films were evaluated using 2θ/θ XRD, and were considered to be the pseudocubic perovskite structure with preferential (001) orientation and no (111) orientation. Here, we applied the new method using XRD reciprocal space maps, and discovered that the (K,Na)NbO3 films had some degree of KNN(111) orientation. We calculated the KNN(001)- and KNN(111)-orientation volume fractions for the (K,Na)NbO3 films from the (101) diffraction peaks originating from the KNN(001)- and KNN(111)-orientation elements in the XRD reciprocal space maps, considering the calibration factors obtained from pole-figure simulations, and examined the relationship between the crystal orientation and d
31 piezoelectric coefficient in the (K,Na)NbO3 films. The results indicated that the d
31 piezoelectric coefficient increases with increasing (001)-orientation volume fraction.
Small-Angle X-ray Scattering Measurements of Ionic Liquids Pressurized with Carbon Dioxide Using Titanium Sample Holder: 1-Butyl-3-methylimidazolium Bis(trifluoromethylsulfonyl) Amide Mixtures up to 22 MPa
Authors: Morita Takeshi , Ushio Masayoshi , Kanoh Kaori , Tanaka Eiichi , Nishikawa Keiko
Published: June 2012

A high-pressure sample holder made entirely of titanium and a titanium alloy was constructed for small-angle X-ray scattering (SAXS) measurement of ionic liquids pressurized with CO2. It is designed to vary the path length precisely and perform stable operation at high temperature and pressure, while retaining a constant path length. An in situ beam-monitoring detector for the transmitted X-rays was redesigned and used. SAXS experiments were carried out for an imidazolium-based ionic liquid, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl) amide, pressurized and saturated with CO2. Zero angle scattering intensities, I(0), which directly relate to the mesoscale structural fluctuation, are evaluated from the obtained SAXS intensities. Values of I(0) meaningfully change with the CO2 solubility. By using the constructed apparatuses, the anomalous behavior of CO2 dissolution into ionic liquids is clarified from the viewpoint of the mesoscale structural change of ionic liquids that fluctuated by dissolved CO2. The present system for SAXS measurement is widely applicable to investigations on structural fluctuations of liquids, solutions including phase separated systems, which are the same as the ionic liquids and CO2 mixtures, and amorphous solids under extreme conditions.
Hexagonally Arrayed 17 nm Interpenetrating and Continuous Biphasic Structure via Block-Copolymer-Templating Process
Authors: Yamashita Nanae , Komiyama Hideaki , Zhao Yongbin , Komura Motonori , Iyoda Tomokazu , Nagai Keiji
Published: June 2012

Biphasic and interpenetrating continuous membranes with precisely controlled two-dimensional (2D)-hexagonal nanoperiodicity were fabricated using amphiphilic block copolymer poly(ethylene oxide)-b-polymethacrylate with azobenzene mesogen units in the side chain [PEO
m
-b-PMA(Az)
n
]. On a silica (SiO2) nanodot array templated from the block copolymer membrane, the next phase, such as titanium dioxide (TiO2), or gold (Au), was coated. Herein, the surface modification of the transferred SiO2 nanodot array was crucial to obtaining the interpenetration of the precursor of TiO2 and its continuous contact. The typical size of the hexagonal array (d) and the center-to-center distance (D) of the SiO2 nanodots were (d, D) = (17 nm, 27 nm) and (d, D) = (22 nm, 51 nm), respectively. The interpenetrating and continuous biphasic structure will provide a promising approach to multiferroic materials, interpenetrative heterojunction for solar cells, new integrated catalysts, and so forth.
Enhancement of the Strained Si Forbidden Doublet Transverse Optical Phonon Raman Band for Quantitative Stress Measurement
Authors: Poborchii Vladimir , Tada Tetsuya , Kanayama Toshihiko
Published: June 2012

Using a combination of a radial polarizer with a linear one in the incident light path while measuring the Raman spectra of strained Si (s-Si) with a high-numerical-aperture lens, we succeeded in the clear domination of the forbidden doublet phonon band [transverse optical (TO) phonon for the light directed along the [001] axis of Si] over the allowed singlet longitudinal optical phonon one. This is important for the precise stress-induced TO phonon Raman shift determination and, therefore, for precise quantitative study of the local stress distribution on the (001) Si surface.