bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic CEO Compensation
Authors: EDMANS ALEX , GABAIX XAVIER , SADZIK TOMASZ , SANNIKOV YULIY
Published: September 2012

We study optimal compensation in a dynamic framework where the CEO consumes in multiple periods, can undo the contract by privately saving, and can temporarily inflate earnings. We obtain a simple closed‐form contract that yields clear predictions for how the level and performance sensitivity of pay vary over time and across firms. The contract can be implemented by escrowing the CEO's pay into a “Dynamic Incentive Account” that comprises cash and the firm's equity. The account features state‐dependent rebalancing to ensure its equity proportion is always sufficient to induce effort, and time‐dependent vesting to deter short‐termism.
Financial Flexibility, Bank Capital Flows, and Asset Prices
Authors: PARLOUR CHRISTINE A. , STANTON RICHARD , WALDEN JOHAN
Published: September 2012

In our parsimonious general‐equilibrium model of banking and asset pricing, intermediaries have the expertise to monitor and reallocate capital. We study financial development, intraeconomy capital flows, the size of the banking sector, the value of intermediation, expected market returns, and the risk of bank crashes. Asset pricing implications include: a market's dividend yield is related to its financial flexibility, and capital flows should be important in explaining expected returns and the risk of bank crashes. Our predictions are broadly consistent with the aggregate behavior of U.S. capital markets since 1950.
The Vote Is Cast: The Effect of Corporate Governance on Shareholder Value
Authors: CUÑAT VICENTE , GINE MIREIA , GUADALUPE MARIA
Published: September 2012

This paper investigates whether improvements in the firm's internal corporate governance create value for shareholders. We analyze the market reaction to governance proposals that pass or fail by a small margin of votes in annual meetings. This provides a clean causal estimate that deals with the endogeneity of internal governance rules. We find that passing a proposal leads to significant positive abnormal returns. Adopting one governance proposal increases shareholder value by 2.8%. The market reaction is larger in firms with more antitakeover provisions, higher institutional ownership, and stronger investor activism for proposals sponsored by institutions. In addition, we find that acquisitions and capital expenditures decline and long‐term performance improves.
A Needs Assessment for the Introduction of a Food Science Program at The Univ. of Guyana
Authors: Morrison Donna
Published: September 2012

Abstract:  This research describes the outcome of a needs assessment to determine whether the Univ. of Guyana should introduce a Food Science program. The research design utilized interviews and questionnaires to large manufacturing organizations and agroprocessors to determine if the required skills are available for the manufacturing process. Results revealed that the lack of skills, particularly in food processing, is one factor that has negatively impacted value‐added production in large manufacturing companies; as well as in the micro, small and medium enterprises, limiting the range of products produced by these entities. Based on this, it was established that the university should introduce a program in food science and be the focus for formal training to satisfy the demands of the food manufacturing industry.
Higher Education Science Student Perspectives on Classroom Instructional Methods: A Pilot Study
Authors: Bohlscheid Jeffri C. , Davis John C.
Published: September 2012

Abstract:  Constructivist‐based inquiry instruction has been popularized for several decades in primary‐ and secondary‐science education, with overwhelmingly positive results across all sciences. Importantly, higher education faculties have begun to embrace inquiry instruction in many subject areas. In fact, a growing body of literature illustrates the positive impact of inquiry instructional methods on science student achievement, such as in Food Science. While it has long been shown that student's instructional preference has a positive impact upon achievement, very little work has been done to assess college student's instructional preferences, especially in lecture‐based classes. A recent study was conducted at the Univ. of Idaho to identify student preferences of generic instructional models. Students from 4 majors (Food Science, Geological Sciences, Secondary Education, and Elementary Education) participated in the study. A 35‐question survey was developed to gather data on student's instructional strategy preferences. The data were analyzed to determine (a) instructional preferences inclusive of all majors, (b) instructional preference within each of the 4 majors, (c) a comparison of preferences of each major to other majors, and (d) gender issues within and across majors. The results suggest that there is perceived value of particular instructional methods over others, both within and across majors. In addition a gender relationship with methodology exists, particularly within certain subject areas.
Looking for a needle in a haystack: inference about individual fitness components in a heterogeneous population
Authors: Cam Emmanuelle , Gimenez Olivier , Alpizar‐Jara Russell , Aubry Lise M. , Authier Matthieu , Cooch Evan G. , Koons David N. , Link William A. , Monnat Jean‐Yves , Nichols James D. , Rotella Jay J. , Royle Jeffrey A. , Pradel Roger
Published: September 2012

Studies of wild vertebrates have provided evidence of substantial differences in lifetime reproduction among individuals and the sequences of life history ‘states’ during life (breeding, nonbreeding, etc.). Such differences may reflect ‘fixed’ differences in fitness components among individuals determined before, or at the onset of reproductive life. Many retrospective life history studies have translated this idea by assuming a ‘latent’ unobserved heterogeneity resulting in a fixed hierarchy among individuals in fitness components. Alternatively, fixed differences among individuals are not necessarily needed to account for observed levels of individual heterogeneity in life histories. Individuals with identical fitness traits may stochastically experience different outcomes for breeding and survival through life that lead to a diversity of ‘state’ sequences with some individuals living longer and being more productive than others, by chance alone. The question is whether individuals differ in their underlying fitness components in ways that cannot be explained by observable ‘states’ such as age, previous breeding success, etc. Here, we compare statistical models that represent these opposing hypotheses, and mixtures of them, using data from kittiwakes. We constructed models that accounted for observed covariates, individual random effects (unobserved heterogeneity), first‐order Markovian transitions between observed states, or combinations of these features. We show that individual sequences of states are better accounted for by models incorporating unobserved heterogeneity than by models including first‐order Markov processes alone, or a combination of both. If we had not considered individual heterogeneity, models including Markovian transitions would have been the best performing ones. We also show that inference about age‐related changes in fitness components is sensitive to incorporation of underlying individual heterogeneity in models. Our approach provides insight into the sources of individual heterogeneity in life histories, and can be applied to other data sets to examine the ubiquity of our results across the tree of life.
Now or Never: Perceived HIV Status and Fertility Intentions in Rural Mozambique
Authors: Hayford Sarah R. , Agadjanian Victor , Luz Luciana
Published: September 2012

As the HIV epidemic evolves, researchers are devoting increased attention to the infection's effect on various life‐course activities, including marriage and reproduction. The impact of HIV on decisions about childbearing is particularly important, given the role that vertical transmission plays in the persistence of the epidemic. Previous studies on HIV and fertility intentions have yielded inconsistent results. This article expands on prior research by taking into account preferred timing of childbearing. Using data from a population‐based survey in rural Mozambique, we show that higher perceived risk of HIV is associated with greater likelihood of both wanting to speed up childbearing and wanting to stop having children. The “now or never” approach to childbearing is shown to be consistent with the widely held belief that HIV infection is incompatible with childbearing in the long term.
Testosterone Deficiency in Men: Systematic Review and Standard Operating Procedures for Diagnosis and Treatment
Authors: Buvat Jacques , Maggi Mario , Guay André , Torres Luiz Otavio
Published: September 2012

Introduction

Testosterone (T) deficiency (TD) may significantly affect sexual function and multiple organ systems.

Aim

To provide recommendations and Standard Operating Procedures (SOPs) based on best evidence for diagnosis and treatment of TD in men

Methods

Medical literature was reviewed by the Endocrine subcommittee of the ISSM Standards Committee, followed by extensive internal discussion over two years, then public presentation and discussion with other experts

Main Outcome Measure

Recommendations and SOPs based on grading of evidence-based medical literature and interactive discussion

Results

TD is the association of a low serum T with consistent symptoms or signs. T level tends to decline with age. T modulates sexual motivation and erection. It also plays a broader role in men's health. Recent studies have established associations between low T, male sexual dysfunctions and metabolic risk factors. Though association does not mean causation, low T is associated with reduced longevity, risk of fatal cardiovascular events, obesity, sarcopenia, mobility limitations, osteoporosis, frailty, cognitive impairment, depression, Sleep Apnea Syndrome, and other chronic diseases. The paper proposes a standardized process for diagnosis and treatment of TD, and updates the knowledge on T therapy (Tth) and prostate and cardiovascular safety. There is no compelling evidence that Tth causes prostate cancer or its progression in men without severe TD. Polycythemia is presently the only cardiovascular-related adverse-event significantly associated with Tth. But follow-up of controlled T trials is limited to 3 years

Conclusions

Men with sexual dysfunctions, and/or with visceral obesity and metabolic diseases should be screened for TD and treated. Young men with TD should also be treated. Benefits and risks of Tth should be carefully assessed in older men. Prospective, long-term, placebo-controlled, interventional studies are required before screening for TD in more conditions, including cardiovascular diseases, and considering correction of TD as preventive medicine.
SOP: Corpus Cavernosum Assessment (Cavernosography/Cavernosometry)
Authors: Glina Sidney , Ghanem Hussein
Published: September 2012

Introduction

There is no universal gold standard diagnostic test to differentiate psychogenic from organic erectile dysfunction (ED). Cavernosography/cavernosometry has been used to evaluate veno-occlusive dysfunction (VOD) in men with a proposed organic ED.

Aim

To develop evidence-based guidelines for the performance and interpretation of cavernosography/cavernosometry.

Methods

Review the methodology behind cavernosography/cavernosometry and evaluate the evidence that supports its use and interpretation of results.

Main Outcome Measure

Expert opinion based on review of the literature, extensive internal committee discussion, public presentation, and debate.

Results

The detailed technique of cavernosography/cavernosometry is described. An evidence-based perspective to the use and interpretation of cavernosometry is presented.

Conclusion

The positive predictive value of cavernosometry still needs further assessment. It is unknown how many potent men would test positive for VOD (false positive).
Standard Operating Procedures for Taking a Sexual History
Authors: Althof Stanley E. , Rosen Raymond C. , Perelman Michael A. , Rubio-Aurioles Eusebio
Published: September 2012

Introduction

While there is evidence of increased professional and public awareness of sexual problems, both male and female sexual dysfunctions remain underdiagnosed and undertreated by health care professionals around the world. Health care professionals (HCPs) are typically reluctant, disinterested, or unskilled in sexual problem management and regrettably are often disinclined to inquire about sexual issues. HCPs in all countries receive variable, nonstandardized, or inadequate training in sexual history taking and its treatment.

Aim

This article presents a standard operating procedure (SOP) for taking a sexual history from men or women with sexual problems or performance concerns.

Methods

Review of relevant evidence-based literature identified through a PubMed search, integrated with expert opinion.

Results

Guidelines for taking a sexual history are presented along with the relevant domains, opening and follow-up questions.

conclusion

The SOP presented in this article offers HCPs a brief, structured, and uniform method for obtaining a sexual history from men or women seeking health care services. Sexual history taking should be based on three basic principles, which serve as the foundation for managing sexual problems in men and women. These include the following: (i) a patient-centered approach; (ii) evidenced-based diagnostic and treatment recommendations; and (iii) use of a unified management approach for men and women. Sexual history taking should always be conducted in a culturally sensitive manner, taking account of the individual's background and lifestyle, status of the partner relationship, and the clinician's comfort and experience with the topic. Sexual inquiry should be incorporated into all new patient encounters, when possible, if only to ask one or two broad questions such as the following: “Are you sexually active? Do you have any sexual concerns or problems you would like to discuss?” Sexual history taking is a cornerstone of sexual medicine clinical practice. All patients should be provided an opportunity for frank and open discussion of sexual issues or concerns, conducted in an atmosphere of sensitivity and respect.
Standard Operating Procedures in the Disorders of Orgasm and Ejaculation
Authors: McMahon Chris G. , Jannini Emmanuele , Waldinger Marcel , Rowland David
Published: September 2012

Introduction

Ejaculatory/orgasmic disorders are common male sexual dysfunctions and include premature ejaculation (PE), inhibited ejaculation, anejaculation, retrograde ejaculation, and anorgasmia.

Aim

To provide recommendations and guidelines of the current state-of-the-art knowledge for management of ejaculation/orgasmic disorders in men as standard operating procedures (SOPs) for the treating health care professional.

Methods

The International Society of Sexual Medicine Standards Committee assembled over 30 multidisciplinary experts to establish SOPs for various male and female sexual medicine topics. The SOP for the management of disorders of orgasm and ejaculation represents the opinion of four experts from four countries developed in a process over a 2-year period.

Main Outcome Measure

Expert opinion was based on grading of evidence-based medical literature, limited expert opinion, widespread internal committee discussion, public presentation, and debate.

Results

PE management is largely dependent upon etiology. Lifelong PE is best managed with PE pharmacotherapy (selective serotonin reuptake inhibitors and/or topical anesthetics). The management of acquired PE is etiology specific and may include erectile dysfunction (ED) pharmacotherapy in men with comorbid ED. All men seeking treatment for PE should receive basic psychosexual education. Graded behavioral therapy is indicated when psychogenic or relationship factors are present and is often best combined with PE pharmacotherapy in an integrated treatment program. Delayed ejaculation, anejaculation, and/or anorgasmia may have a biogenic and/or psychogenic etiology. Men with age-related penile hypoanesthesia should be educated, reassured, and instructed in revised sexual techniques which maximize arousal. Retrograde ejaculation is managed by education, patient reassurance, and pharmacotherapy.

Conclusions

Additional research is required to further the understanding of the disorders of ejaculation and orgasm.
Canonical TGF‐β Pathway Activity Is a Predictor of SHH‐Driven Medulloblastoma Survival and Delineates Putative Precursors in Cerebellar Development
Authors: Aref Donya , Moffatt Connor J. , Agnihotri Sameer , Ramaswamy Vijay , Dubuc Adrian M. , Northcott Paul A. , Taylor Michael D. , Perry Arie , Olson James M. , Eberhart Charles G. , Croul Sidney E.
Published: September 2012

Medulloblastoma (MB) is the most common malignant brain tumor of childhood. Very little is known about aggressive forms of this disease, such as metastatic or recurrent MBs. In order to identify pathways involved in aggressive MB pathophysiology, we performed unbiased, whole genome microarrays on MB tumors at both the human and murine levels. Primary human MBs were compared, transcriptomically, to their patient‐matched recurrent or metastatic tumors. Expression profiling was also performed on murine tumors from two spontaneously developing MB mouse models (Ptch+/− and Smo/Smo) that present with differing clinical severities. At both the human and murine levels we identified transforming growth factor‐beta (TGF‐β) as a potential contributor to MB progression/metastasis. Smad3, a major downstream component of the TGF‐β pathway, was also evaluated using immunohistochemistry in malignant human tissues and was shown to correlate with MB metastasis and survival. Similarly, Smad3 expression during development identified a subset of cerebellar neuronal precursors as putative cells of origin for the Smad3‐positive MBs. To our knowledge, this is the first study that links TGF‐β to MB pathogenesis. Our research suggests that canonical activation of this pathway leads to better prognosis for patients.
Spectral optical coherence tomography findings in patients with ocular toxoplasmosis and active satellite lesions (MINAS Report 1)
Authors: Oréfice Juliana L. , Costa Rogério A. , Scott Ingrid U. , Calucci Daniela , Oréfice Fernando ,   on behalf of the Grupo Mineiro de Pesquisa em Doenças Oculares Inflamatórias (MINAS)
Published: September 2012

Purpose:  To characterize the active retinochoroiditis lesion observed in patients with the classic clinical presentation of ocular toxoplasmosis (OT) utilizing spectral optical coherence tomography (SOCT).

Methods:  Twenty‐four patients with OT and satellite lesions underwent standardized ophthalmologic examination and multimodal fundus imaging. The SOCT findings observed at presentation were described.

Results:  The mean age of the fourteen (58.3%) women and ten (41.7%) men was 27.6 years. The mean LogMAR ETDRS best‐corrected visual acuity was 0.58 (Snellen equivalent, 20/80+1). On SOCT evaluation, the posterior hyaloid was diffusely thickened in 23 (95.8%) of 24 eyes, increased hyper‐reflective signals in the vitreous were observed in 18 (75.0%), and vitreal spherical hyper‐reflective depositions were observed in 12 (50.0%) eyes. In all patients, at the active OT lesion site, the inner retinal layers were abnormally hyper‐reflective with full‐thickness disorganization of the retinal reflective layers (smudge effect); associated choriocapillaris/choroidal optical shadowing was observed in 22 (91.7%) eyes. The retina was thickened in 22 (91.7%) eyes, the retinal pigment epithelium‐Bruch membrane reflective complex was focally increased or contained focal splits in 16 (66.7%) eyes and the choroid appeared thickened in 17 (70.8%) eyes. Disorganization of the outer retinal highly reflective layers adjacent to the active OT lesion was observed in all eyes.

Conclusion:  Full‐thickness disorganization of the retinal reflective layers, generally associated with some degree of posterior optical shadowing, was observed in the active OT lesion in all patients. The posterior hyaloid was often thickened and, adjacent to the OT lesion, the outer retina was consistently altered.
Quantification of Yield Losses Due to Anthracnose Stalk Rot on Corn in Brazilian Conditions
Authors: Cota Luciano V. , da Costa Rodrigo V. , Silva Dagma D. , Casela Carlos R. , Parreira Douglas F.
Published: September 2012

The anthracnose stalk rot of corn (ASR), caused by Colletotrichum graminicola, is a major disease of this crop and occurs in most Brazilian regions where corn is grown. Despite its widespread occurrence, there are no estimates of the effect of ASR on the yield of corn under the Brazilian conditions. In this study, we evaluated the effect of ASR on corn hybrids yield. Two experiments were conducted (first crop 2007/2008 and second crop, 2009) in areas with a history of occurrence of leaf anthracnose and ASR. Five hybrids were evaluated in the first and second crops: AG1051, BRS 1001, BRS 1010, BRS 1035, P30F80 and BRS 1010, 2B710, P30F80, DKB390, BRS 1035, respectively. At harvest, we evaluated the incidence of plants with anthracnose stalk rot (IPASR), and we selected pairs of healthy and diseased plants to quantify the effect of ASR in the ear weight (EW), grain weight (GW) and the weight of a sample containing 100 kernels (W100). The IPASR was higher in the hybrid BRS 1010 (21.87 and 45.28%, first and second crops, respectively). The EW, GW and W100 were lower in diseased plants in all hybrids. The mean weight loss in the first season was EW 29.03%, GW 27.83% and W100 17.08%, and the second season was EW 27.75%, GW 25.60% and W100 16.99%. The most affected hybrids with weight loss in the first crop were AG1051 (EW 34.31%, GW 33.05%, W100 19.96%) and BRS 1035 (EW 34.74%, GW 34.65%, W100 22.31%). In the second crop, were P30F80 (EW 30.72%, GW 30.92%, W100 19.24%), DKB390 (EW 30.61%, GW 29.81%) and 2B710 (W100 19.27%). Corn yield was strongly affected by ASR.
Genomic and phenotypic architecture of a spruce hybrid zone (Picea sitchensis × P. glauca)
Authors: Hamilton Jill A. , Lexer Christian , Aitken Sally N.
Published: September 2012

Interspecific hybridization may enhance the capacity of populations to adapt to changing environments, and has practical implications for reforestation. We use genome‐wide estimates of admixture and phenotypic traits for trees in a common garden to examine the extent and direction of gene flow across aPiceahybrid zone, testing assumptions of the bounded hybrid superiority and tension zone models of hybrid zone maintenance. Seeds were collected from the ecological transition zone spanning from maritime to continental climates across thePicea sitchensis–P. glaucacontact zone, and 721 trees were planted in a common garden experiment within the hybrid zone. Individuals were genotyped using a panel of 384 candidate‐gene single nucleotide polymorphisms (SNPs) putatively associated with adaptive traits inPicea, and phenotyped at age ten for height and autumn cold hardiness. Low interspecific heterozygosity in hybrids indicated that intrinsic reproductive barriers were too weak to prevent widespread recombination, although introgression appeared asymmetric withP. sitchensisdominating the zone. Whereas marker‐based hybrid index was strongly correlated with climate and geography, phenotypic traits exhibited weak or no significant clines. Our results indicated that exogenous selection appeared to play a strong role in the distribution and structure of this hybrid zone, indicative of an environmentally determined bounded hybrid superiority model of hybrid zone maintenance, although endogenous mechanisms could not be ruled out. This study provides insight into the mechanisms underlying adaptation across ecologically transitional hybrid zones that will ultimately provide an additional tool in managing these economically important tree species.
Matrix metalloproteinases: do they play a role in mucosal pathology of the oral cavity?
Authors: Al‐Azri AR , Gibson RJ , Keefe DMK , Logan RM
Published: September 2012

Matrix metalloproteinases (MMPs) are critical factors in maintaining the integrity of mucosa and mediating normal biological processes. An imbalance between tissue levels of these mediators and their natural inhibitors is believed to underlie the pathophysiology of many diseases, including those affect the gastrointestinal and oral mucosae. The ongoing development of synthetic inhibitors of these mediators may provide opportunities to develop treatment modalities for patients suffering from these diseases. Understanding the role of MMPs in the pathophysiology of many diseases, however, is far from complete, and the improvement of pharmaceutical management strategies can only be achieved if the underlying process of these diseases is completely comprehended. This paper reviews the functions of matrix metalloproteinases and addresses their role in mediating mucosal pathologies with emphasis on oral mucosa.
Simulation in pediatric anesthesiology
Authors: Fehr James J. , Honkanen Anita , Murray David J.
Published: September 2012

Simulation‐based training, research and quality initiatives are expanding in pediatric anesthesiology just as in other medical specialties. Various modalities are available, from task trainers to standardized patients, and from computer‐based simulations to mannequins. Computer‐controlled mannequins can simulate pediatric vital signs with reasonable reliability; however the fidelity of skin temperature and color change, airway reflexes and breath and heart sounds remains rudimentary. Current pediatric mannequins are utilized in simulation centers, throughout hospitals in‐situ, at national meetings for continuing medical education and in research into individual and team performance. Ongoing efforts by pediatric anesthesiologists dedicated to using simulation to improve patient care and educational delivery will result in further dissemination of this technology. Health care professionals who provide complex, subspecialty care to children require a curriculum supported by an active learning environment where skills directly relevant to pediatric care can be developed. The approach is not only the most effective method to educate adult learners, but meets calls for education reform and offers the potential to guide efforts toward evaluating competence. Simulation addresses patient safety imperatives by providing a method for trainees to develop skills and experience in various management strategies, without risk to the health and life of a child. A curriculum that provides pediatric anesthesiologists with the range of skills required in clinical practice settings must include a relatively broad range of task‐training devises and electromechanical mannequins. Challenges remain in defining the best integration of this modality into training and clinical practice to meet the needs of pediatric patients.
Parker-Type Acoustic Resonances in the Return Guide Vane Cascade of a Centrifugal Compressor – Theoretical Modeling and Experimental Verification
Authors: König Sven , Petry Nico
Published: September 2012

The potential of acoustic resonances within vane arrays of turbomachinery has been known since the fundamental investigations of Parker back in the sixties and seventies. In his basic studies on flat plate arrays (and later on for an axial compressor) he could show that vortex shedding from the respective trailing edges may excite acoustic resonances that are localized to the vaned flow region. In principle, such phenomena are conceivable for any kind of turbomachinery; however, no such investigations are publicly available for the centrifugal type. The current investigation is one part of an extended research program to gain a better understanding of excitation and noise generating mechanism in centrifugal compressors, and focuses on Parker-type acoustic resonances within the return guide vane cascade of a high-pressure centrifugal compressor. A simplified model to calculate the respective acoustic eigenfrequencies is presented, and the results are compared with finite element analyses. Furthermore, the calculated mode shapes and frequencies are compared with experimental results. It is shown that for high-pressure centrifugal compressors, according to the nomenclature of Parker, acoustic modes of the α, β, γ, and δ type exist over a wide operating range within the return guide vane cascade. For engine representative Reynolds numbers, the experimental results indicate that the vortex shedding frequencies from the vane trailing edges cannot be characterized by a definite Strouhal number; the excitation of the Parker-type acoustic modes is mostly broadband due to the flow turbulence. No lock-in phenomenon between vortex shedding and acoustic modes takes place, and the amplitudes of the acoustic resonances are too small to cause machines failures or excessive noise levels. The simplified model presented in the current paper has been successfully validated for the return guide vane cascade of a centrifugal compressor but can also be applied for arbitrary blade and vane arrays, given that the chord-to-pitch ratio is sufficiently high. With this model, frequency components in measured pressure signals, that were left unexplained in the past, can be easily inspected for possible Parker-type resonances.
4D patient dose reconstruction using online measured EPID cine images for lung SBRT treatment validation
Authors: Lin Mu‐Han , Li Jinsheng , Wang Lu , Koren Sion , Fan Jiajing , Forkal Eugene , Ma C.‐M.
Published: September 2012

Purpose:

This study aims to develop an EPID‐guided 4D patient dose reconstruction framework and to investigate its feasibility for lung SBRT treatment validation.

Methods:

Both the beam apertures and tumor movements were detected based on the continuously acquired EPID images during the treatment. Instead of directly using the transit photon fluence measured by the EPID, this method reconstructed the entrance fluence with the measured beam apertures and the delivered MUs. The entrance fluence distributions were sorted into their corresponding phases based on the detected tumor motion pattern and then accumulated for each phase. Together with the in‐room 4DCT taken before every treatment to consider the interfractional‐motion, the entrance fluence was then used for the patient dose calculation. Deformable registration was performed to sum up the phase doses for final treatment assessment. The feasibility of using the transit EPID images for entrance fluence reconstruction was evaluated against EPID in‐air measurements. The accuracy of 3D‐ and 4D‐dose reconstruction was validated by experiments with a motor‐driven cylindrical diode array for six clinical‐SBRT plans.

Results:

The average difference between the measured and reconstructed fluence maps was within 0.16%. The reconstructed 3D‐dose showed a less than 1.4% difference for the CAX‐dose and at least a 98.3% gamma‐passing‐rate (2%/2 mm) for the peripheral dose. Distorted dose distributions were observed in the measurement with the moving phantom. The comparison between the measured and the reconstructed 4D‐dose without considering temporal information failed the gamma‐evaluation for most cases. In contrast, when temporal information was considered, the dose distortion phenomena were successfully represented in the reconstructed dose (97.6%–99.7% gamma‐passing rate).

Conclusions:

The proposed method considered uncertainties of the beam delivery system, the interfractional‐ and intrafractional‐motion, and the interplay effect. The experimental validation demonstrates that this method is practical and accurate for online or offline SBRT patient dose verification.
Models of cylindrical bubble pulsation
Authors: Ilinskii Yurii A. , Zabolotskaya Evgenia A. , Hay Todd A. , Hamilton Mark F.
Published: September 2012

Three models are considered for describing the dynamics of a pulsating cylindrical bubble. A linear solution is derived for a cylindrical bubble in an infinite compressible liquid. The solution accounts for losses due to viscosity, heat conduction, and acoustic radiation. It reveals that radiation is the dominant loss mechanism, and that it is 22 times greater than for a spherical bubble of the same radius. The predicted resonance frequency provides a basis of comparison for limiting forms of other models. The second model considered is a commonly used equation in Rayleigh-Plesset form that requires an incompressible liquid to be finite in extent in order for bubble pulsation to occur. The radial extent of the liquid becomes a fitting parameter, and it is found that considerably different values of the parameter are required for modeling inertial motion versus acoustical oscillations. The third model was developed by V. K. Kedrinskii [Hydrodynamics of Explosion (Springer, New York, 2005), pp. 23–26] in the form of the Gilmore equation for compressible liquids of infinite extent. While the correct resonance frequency and loss factor are not recovered from this model in the linear approximation, it provides reasonable agreement with observations of inertial motion.
Production of single and geminate stops in Japanese three- and four-mora words
Authors: Hirata Yukari , Amano Shigeaki
Published: September 2012

This study examined the durational structure of single and geminate stop distinction produced in three- and four-mora words of Japanese, (C1)V1(C2)C2V2X [(C2)C2 = the contrasting consonants; X = a CV mora, the moraic nasal, or a long vowel as part of V2]. The questions addressed were how factors such as speaking rate, segmental variability, and moraic composition of words affected the stop quantity distinction in words longer than well-studied disyllabic words, and whether there exists an invariant parameter that classified these two stop categories. Results showed that all of those factors systematically affected the duration of the contrasting stop closure, the unit of [(C1)V1(C2)C2V2], and the entire three- and four-mora words. However, the durational units of moras and words were well-structured, and the ratio of the contrasting stop closure to the [(C1)V1(C2)C2V2] unit, as well as the ratio of the closure to the entire word, were found to be invariant in indicating the stop quantity distinction. These results support the theory of relational acoustic invariance [Pickett et al., Phonetica 56, 135–157 (1999)] on the part of production. Furthermore, the results provide insight into different versions of Japanese mora hypothesis [Han, The Study of Sounds 10, 65–80 (1962); Port et al., J. Acoust. Soc. Am. 81(5), 1574–1585 (1987)], which have been under debate for five decades.
Asymmetric vibration in a two-layer vocal fold model with left-right stiffness asymmetry: Experiment and simulation
Authors: Zhang Zhaoyan , Hieu Luu Trung
Published: September 2012

Vibration characteristics of a self-oscillating two-layer vocal fold model with left-right asymmetry in body-layer stiffness were experimentally and numerically investigated. Two regimes of distinct vibratory pattern were identified as a function of left-right stiffness mismatch. In the first regime with extremely large left-right stiffness mismatch, phonation onset resulted from an eigenmode synchronization process that involved only eigenmodes of the soft fold. Vocal fold vibration in this regime was dominated by a large-amplitude vibration of the soft fold, and phonation frequency was determined by the properties of the soft fold alone. The stiff fold was only enslaved to vibrate at a much reduced amplitude. In the second regime with small left-right stiffness mismatch, eigenmodes of both folds actively participated in the eigenmode synchronization process. The two folds vibrated with comparable amplitude, but the stiff fold consistently led the soft fold in phase for all conditions. A qualitatively good agreement was obtained between experiment and simulation, although the simulations generally underestimated phonation threshold pressure and onset frequency. The clinical implications of the results of this study are also discussed.
Surface waves on a half space with depth-dependent properties
Authors: Balogun Oluwaseyi , Achenbach Jan D.
Published: September 2012

The dispersive properties of surface waves on an isotropic elastic body with elastic moduli and mass density that depend on depth have been analyzed in the high frequency range, for the case of axially symmetric surface waves, which are of interest for point loading of a body. The method of approach requires some simplifications, but the final analysis yields simple expressions for the displacements, for the case that the two elastic moduli and the mass density each have different dependencies on depth. In a high-frequency approximation expressions are obtained for the displacements and the stresses. The condition that the surface tractions vanish at the free surface yields the dispersion equation which relates the surface wave velocity to the wavenumber. Conditions have been derived for a class of examples for which this equation yields a real valued surface wave velocity, and the displacement amplitudes decay exponentially with depth. Results for the surface wave velocity as a function of the wavenumber have been compared with numerical results which were obtained when the continuous inhomogeneity with depth is replaced by an equivalent layering. For some typical cases of increasing and decreasing material properties with depth, excellent agreement has been obtained between analytical and numerical results.
Binaural interaction and the octave illusion
Authors: Lamminmäki Satu , Mandel Anne , Parkkonen Lauri , Hari Riitta
Published: September 2012

The auditory octave illusion arises when dichotically presented tones, one octave apart, alternate rapidly between the ears. Most subjects perceive an illusory sequence of monaural tones: A high tone in the right ear (RE) alternates with a low tone, incorrectly localized to the left ear (LE). Behavioral studies suggest that the perceived pitch follows the RE input, and the perceived location the higher-frequency sound. To explore the link between the perceived pitches and brain-level interactions of dichotic tones, magnetoencephalographic responses were recorded to 4 binaural combinations of 2-min long continuous 400- and 800-Hz tones and to 4 monaural tones. Responses to LE and RE inputs were distinguished by frequency-tagging the ear-specific stimuli at different modulation frequencies. During dichotic presentation, ipsilateral LE tones elicited weaker and ipsilateral RE tones stronger responses than when both ears received the same tone. During the most paradoxical stimulus—high tone to LE and low tone to RE perceived as a low tone in LE during the illusion—also the contralateral responses to LE tones were diminished. The results demonstrate modified binaural interaction of dichotic tones one octave apart, suggesting that this interaction contributes to pitch perception during the octave illusion.
Near-field acoustic holography using sparse regularization and compressive sampling principles
Authors: Chardon Gilles , Daudet Laurent , Peillot Antoine , Ollivier François , Bertin Nancy , Gribonval Rémi
Published: September 2012

Regularization of the inverse problem is a complex issue when using near-field acoustic holography (NAH) techniques to identify the vibrating sources. This paper shows that, for convex homogeneous plates with arbitrary boundary conditions, alternative regularization schemes can be developed based on the sparsity of the normal velocity of the plate in a well-designed basis, i.e., the possibility to approximate it as a weighted sum of few elementary basis functions. In particular, these techniques can handle discontinuities of the velocity field at the boundaries, which can be problematic with standard techniques. This comes at the cost of a higher computational complexity to solve the associated optimization problem, though it remains easily tractable with out-of-the-box software. Furthermore, this sparsity framework allows us to take advantage of the concept of compressive sampling; under some conditions on the sampling process (here, the design of a random array, which can be numerically and experimentally validated), it is possible to reconstruct the sparse signals with significantly less measurements (i.e., microphones) than classically required. After introducing the different concepts, this paper presents numerical and experimental results of NAH with two plate geometries, and compares the advantages and limitations of these sparsity-based techniques over standard Tikhonov regularization.
Ultrasonic resonant modes of piezoelectric balloons under internal pressure
Authors: Vidal Denham Lori , Rice David A.
Published: September 2012

Properties of a piezoelectric polymeric angioplasty balloon that may decrease the problems of acute closure and restenosis are evaluated in this study. Polyvinylidene difluoride (PVDF), a piezoelectric and pyroelectric polymer, has sufficient strength to serve as a standard angioplasty balloon as well as functioning as an ultrasonic transmitter and/or receiver. These properties enable potential therapeutic applications using ultrasound such as plaque ablation and sonotherapy as well as vulnerable plaque diagnosis using thermography. This study investigates the resonant structure of the PVDF balloon catheter in the frequency range 5–100 kHz. Vibrations of the piezoelectric balloon are modeled using cylindrical shell theory and compared with the observed modal frequencies of PVDF cylinders with and without internal pressure. Modal frequencies are determined by measuring the near-field pressure response of the PVDF cylinders using a high frequency microphone. A rich nodal structure is observed between 5 and 100 kHz with peak relative amplitudes measured between 42 and 45 kHz. Higher order modes for cylinders with 9 μm and 28 μm wall thickness increase in frequency as the internal pressure is increased. Experimental measurements confirm theoretical models that predict both pressure-dependent and pressure-independent resonant frequencies. Frequencies of pressure-dependent modes are calculated within 2.2% of measured values at high pressure.
Architectural shape and early acoustic efficiency in concert halls (L)
Authors: Jurkiewicz Yann , Wulfrank Thomas , Kahle Eckhard
Published: September 2012

Supplying sufficient early reflections to audience members is an important prerequisite to good acoustic quality in performing arts spaces. However, the relationship between the geometry of a room and its acoustic efficiency in terms of early energy has rarely been investigated using basic geometrical principles. The present study demonstrates the possibility of predicting the average value of early reflected energy across the audience area using solid angles. The formulas obtained display the influence of various factors on average early energy; in particular, the direction of arrival of early reflections is found to play a significant role, which highlights interesting implications for the acoustic design of concert halls.
Thresholds for the slope ratio in determining transition time and quantifying diffuser performance in situ
Authors: Jeong Cheol-Ho , Jacobsen Finn , Brunskog Jonas
Published: September 2012

This study is concerned with an objective measure called the slope ratio that can detect acoustic defects due to unexpected pressure increases such as strong reflections and coincidental constructive interference. The slope ratio is the ratio of the instantaneous slope to the mean slope in a decay curve. The slope ratio was suggested for determining the room acoustic transition time experimentally, but its threshold criteria have not been thoroughly investigated. The thresholds for the slope ratio, particularly for applications such as determining the room acoustic transition time and quantifying in situ diffuseness, are examined for various room impulse responses. For the tested rooms, a slope ratio threshold of 11 gives the most consistent and systematic results.
Rigid sphere room impulse response simulation: Algorithm and applications
Authors: Jarrett D. P. , Habets E. A. P. , Thomas M. R. P. , Naylor P. A.
Published: September 2012

Simulated room impulse responses have been proven to be both useful and indispensable for comprehensive testing of acoustic signal processing algorithms while controlling parameters such as the reverberation time, room dimensions, and source–array distance. In this work, a method is proposed for simulating the room impulse responses between a sound source and the microphones positioned on a spherical array. The method takes into account specular reflections of the source by employing the well-known image method, and scattering from the rigid sphere by employing spherical harmonic decomposition. Pseudocode for the proposed method is provided, taking into account various optimizations to reduce the computational complexity. The magnitude and phase errors that result from the finite order spherical harmonic decomposition are analyzed and general guidelines for the order selection are provided. Three examples are presented: an analysis of a diffuse reverberant sound field, a study of binaural cues in the presence of reverberation, and an illustration of the algorithm’s use as a mouth simulator.
The effect of compression speed on intelligibility: Simulated hearing-aid processing with and without original temporal fine structure information
Authors: Hopkins Kathryn , King Andrew , Moore Brian C. J.
Published: September 2012

Hearing aids use amplitude compression to compensate for the effects of loudness recruitment. The compression speed that gives the best speech intelligibility varies among individuals. Moore [(2008). Trends Amplif. 12, 300–315] suggested that an individual’s sensitivity to temporal fine structure (TFS) information may affect which compression speed gives most benefit. This hypothesis was tested using normal-hearing listeners with a simulated hearing loss. Sentences in a competing talker background were processed using multi-channel fast or slow compression followed by a simulation of threshold elevation and loudness recruitment. Signals were either tone vocoded with 1-ERBN-wide channels (where ERBN is the bandwidth of normal auditory filters) to remove the original TFS information, or not processed further. In a second experiment, signals were vocoded with either 1 - or 2-ERBN-wide channels, to test whether the available spectral detail affects the optimal compression speed. Intelligibility was significantly better for fast than slow compression regardless of vocoder channel bandwidth. The results suggest that the availability of original TFS or detailed spectral information does not affect the optimal compression speed. This conclusion is tentative, since while the vocoder processing removed the original TFS information, listeners may have used the altered TFS in the vocoded signals.
Analysis of high-frequency energy in long-term average spectra of singing, speech, and voiceless fricatives
Authors: Monson Brian B. , Lotto Andrew J. , Story Brad H.
Published: September 2012

The human singing and speech spectrum includes energy above 5 kHz. To begin an in-depth exploration of this high-frequency energy (HFE), a database of anechoic high-fidelity recordings of singers and talkers was created and analyzed. Third-octave band analysis from the long-term average spectra showed that production level (soft vs normal vs loud), production mode (singing vs speech), and phoneme (for voiceless fricatives) all significantly affected HFE characteristics. Specifically, increased production level caused an increase in absolute HFE level, but a decrease in relative HFE level. Singing exhibited higher levels of HFE than speech in the soft and normal conditions, but not in the loud condition. Third-octave band levels distinguished phoneme class of voiceless fricatives. Female HFE levels were significantly greater than male levels only above 11 kHz. This information is pertinent to various areas of acoustics, including vocal tract modeling, voice synthesis, augmentative hearing technology (hearing aids and cochlear implants), and training/therapy for singing and speech.