bluuebunny/crossref_metadata_2025 huggingface dataset:
Merely a stepping stone? Professional identity and career prospects following postgraduate mental health nurse training
Authors: McCrae N. , Askey‐Jones S. , Laker C.
Published: February 2014

Accessible summary

Accelerated mental health nurse training attracts talented graduates, many with a psychology degree.

Our study shows that such trainees feel incompatible with the nursing culture.

Consequently, professional identification is inhibited, and on qualifying these nurses may choose to develop their careers elsewhere.

Nurse educators and mentors should pay greater attention to nurturing a positive professional identity in trainees.

Alongside their attainment of knowledge and skills, nursing trainees are moulded by a professional culture and inculcated to norms of beliefs and behaviour. The process of professional identification may be inhibited by accelerated nurse training and an influx of psychology graduates potentially using mental health nursing qualification as a springboard to other career opportunities. This study explored facilitators and barriers to professional identification in newly qualified nurses of accelerated postgraduate training. Qualitative interviews were conducted with 10 nurses who had recently completed a postgraduate diploma in mental health nursing at King's College London. Participants identified more with the mental health field than with the broader profession of nursing. They defined their practice in terms of values rather than skills and found difficulty in articulating a distinct role for mental health nursing. Although participants had found experience in training and as a registered practitioner rewarding, they were concerned that nursing may not fulfil their aspirations. Professional identity is likely to be a major factor in satisfaction and retention of nurses. Training and continuing professional development should promote career advancement within clinical nursing practice.
Effects of light and circadian clock on growth and chlorophyll accumulation of Nannochloropsis gaditana
Authors: Braun Regina , Farré Eva M. , Schurr Ulrich , Matsubara Shizue
Published: February 2014

Circadian clocks synchronize various physiological, metabolic and developmental processes of organisms with specific phases of recurring changes in their environment (e.g. day and night or seasons). Here, we investigated whether the circadian clock plays a role in regulation of growth and chlorophyll (Chl) accumulation in Nannochloropsis gaditana, an oleaginous marine microalga which is considered as a potential feedstock for biofuels and for which a draft genome sequence has been published. Optical density (OD) of N. gaditana culture was monitored at 680 and 735 nm under 12:12 h or 18:6 h light‐dark (LD) cycles and after switching to continuous illumination in photobioreactors. In parallel, Chl fluorescence was measured to assess the quantum yield of photosystem II. Furthermore, to test if red‐ or blue‐light photoreceptors are involved in clock entrainment in N. gaditana, some of the experiments were conducted by using only red or blue light. Growth and Chl accumulation were confined to light periods in the LD cycles, increasing more strongly in the first half than in the second half of the light periods. After switching to continuous light, rhythmic oscillations continued (especially for OD680) at least in the first 24 h, with a 50% decrease in the capacity to grow and accumulate Chl during the first subjective night. Pronounced free‐running oscillations were induced by blue light, but not by red light. In contrast, the photosystem II quantum yield was determined by light conditions. The results indicate interactions between circadian and light regulation of growth and Chl accumulation in N. gaditana.
Genotype I of hepatitis B virus was found in east Xishuangbanna, China and molecular dynamics of HBV/I
Authors: Shen T. , Yan X. M. , Liu H .X. , Zhang B. X. , Li L. , Zhang J. P. , Wang J. L. , Xiao C. J.
Published: February 2014

There is a dearth of data about the prevalence of hepatitis B virus (HBV) infection in Mengla, China; and no detailed analysis of the molecular evolution of genotype I in Asia. In this study, 909 serum samples from ethnic minority people in China were obtained. Serological assay and HBV S‐gene amplification were carried out, and phylogenetic and evolutionary dynamics analysis of 62 HBV/I S‐gene was performed. On this survey, 153 individuals were tested HBsAg‐positive. Genotypes of S‐gene were classified into three groups: C, B and I. Under the strict model and the relax model, the estimated evolutionary rates for HBV/I were 3.74 × 10−4 and 6.93 × 10−4 substitution/site/year, respectively. However, when the geographic origin was taken into account, the mean substitution rates were increased. Estimated time to most recent ancestor of genotype I varied from ~30 to ~70 years ago. The Bayesian sky plot showed a rapid spread of HBV/I at the end of 1980s. Peculiar nucleotides distributed were observed in the subgenotype I1/I2. In conclusion, higher prevalence of HBV infection was observed in Mengla county. Multifactors like timescale and spatial locations should be integrated to provide a better interpretation of the HBV/I evolutionary history in the region.
Rice protein‐induced enterocolitis syndrome with transient specific IgE to boiled rice but not to retort‐processed rice
Authors: Yasutomi Motoko , Kosaka Takuya , Kawakita Akiko , Hayashi Hisako , Okazaki Shintaro , Murai Hiroki , Miyagawa Kazuhiko , Mayumi Mitsufumi , Ohshima Yusei
Published: February 2014

Described herein is the case of an 8‐month‐old girl with atypical food protein‐induced enterocolitis syndrome due to rice. She presented with vomiting and poor general activity 2 h after ingestion of boiled rice. Oral food challenge test using high‐pressure retort‐processed rice was negative, but re‐exposure to boiled rice elicited gastrointestinal symptoms. On western blot analysis the patient's serum was found to contain IgE bound to crude protein extracts from rice seed or boiled rice, but not from retort‐processed rice. The major protein bands were not detected in the electrophoresed gel of retort‐processed rice extracts, suggesting decomposition by high‐temperature and high‐pressure processing. Oral food challenge for diagnosing rice allergy should be performed with boiled rice to avoid a false negative. Additionally, some patients with rice allergy might be able to ingest retort‐processed rice as a substitute for boiled rice.
Philosophy in Law? A Legal‐Philosophical Inquiry
Authors: Rosenfeld Michel
Published: February 2014

Going beyond the debate between positivists and proponents of natural law, there is a controversy over whether there can or ought to be “philosophy in law” (i.e., whether anything within the subject‐matter of philosophy can also become part of the subject‐matter of law). According to Luhmann's autopoietic theory, law is a normatively closed system and accordingly remains completely independent from philosophy. Dworkin, on the other hand, asserts that constitutional law depends for its coherence and integrity on being encompassed within a particular political philosophy. This essay approaches “philosophy in law” from a functional rather than a legitimating perspective, and concludes against both Luhmann and Dworkin that the integration of philosophy in law is interstitial and limited. The consequence of this for law's validity and legitimacy is a likely increase in contestation and contestability. The essay concludes that by embracing pluralism as a philosophy, one can reduce and better manage contestability without ever becoming able to eliminate it.
Reason of State and Public Reason
Authors: Sadurski Wojciech
Published: February 2014

“Reason of state” is a concept that is rarely used in contemporary legal and political philosophy, compared to everyday parlance; “public reason,” in contrast, is ubiquitous, especially in liberal philosophy, as a legitimacy‐conferring device. In this article it is argued that the unpopularity of the notion of “reason of state” is partly due to its notorious ambiguity. Three different usages of the notion can be identified: a “thin” usage (where “reason of state” is equivalent to the common good); an “ironical” usage (where it is used pejoratively to denounce it as a pretext for application of illegitimate or illegal means); and a “pre‐emptive” usage (where “reason of state” functions as a legitimate second‐order exclusionary reason used to override otherwise mandatory first‐order rules of action). It is argued that only the “thin” usage is helpful in a by‐and‐large liberal‐democratic context. The article then discusses the main dilemmas related to the concept of public reason, especially in its most influential, Rawlsian interpretation, and defends the concept against common critiques. Finally, the two concepts of “reason of state” and public reason are compared, and it is argued that a “thin” usage of “reason of state” is functionally equivalent to public reason, and that both resonate with the theory of “input democracy” (focusing, as it does, on the legitimacy of reasons—or motivations—for applying coercive rules to individuals). The article also identifies a problematic feature of “reason of state”: its emphasis on the state as a privileged interpreter of such reasons and/or as identifying the pool of actors within which the “constituency” of public reason is ascertained. There are good reasons to resist both of these consequences: the former because of its potentially authoritarian consequences, the latter because of reasons provided by cosmopolitan political conceptions.
Making Sense of Discrimination
Authors: Segev Re'em
Published: February 2014

Discrimination is a central moral and legal concept. However, it is also a contested one. Particularly, accounts of the wrongness of discrimination often rely on controversial and particular assumptions. In this paper, I argue that a theory of discrimination that relies on premises that are very general (rather than unique to the concept of discrimination) and widely accepted provides a plausible (exhaustive) account of the concept of wrongful discrimination. According to the combined theory, wrongful discrimination consists of allocating a benefit that is not supported by a morally significant fact (a valid reason), or in a way that involves distributive injustice, or both.
Should Empathy Play any Role in the Interpretation of Constitutional Rights?
Authors: Corso Lucia
Published: February 2014

This paper explores the role that empathy can play in the interpretation of constitutional rights. It starts by analyzing the complex concept of empathy, comparing it with similar yet distinct concepts such as projection, sympathy and emotional contagion, then it discusses the widespread distrust of empathy among lawyers and legal thinkers. It will be argued that empathy can play a significant role in the interpretation of constitutional rights, mostly in identifying the interests and needs put forward in the claims and counterclaims of the parties. In the final section, the impact of empathetic judging on judicial minimalism will be briefly discussed.
Interviewer Effects on Non-Response Propensity in Longitudinal Surveys: a Multilevel Modelling Approach
Authors: Vassallo Rebecca , Durrant Gabriele B. , Smith Peter W. F. , Goldstein Harvey
Published: February 2014

The paper investigates two different multilevel approaches, the multilevel cross-classified and the multiple-membership models, for the analysis of interviewer effects on wave non-response in longitudinal surveys. The models proposed incorporate both interviewer and area effects to account for the non-hierarchical structure, the influence of potentially more than one interviewer across waves and possible confounding of area and interviewer effects arising from the non-random allocation of interviewers across areas. The methods are compared by using a data set: the UK Family and Children Survey.
Inference and Forecasting in the Age–Period–Cohort Model with Unknown Exposure with an Application to Mesothelioma Mortality
Authors: Martínez Miranda María Dolores , Nielsen Bent , Nielsen Jens Perch
Published: February 2014

It is of considerable interest to forecast future mesothelioma mortality. No measures for exposure are available so it is not straightforward to apply a dose–response model. It is proposed to model the counts of deaths directly by using a Poisson regression with an age–period–cohort structure, but without offset. Traditionally the age–period–cohort is viewed as suffering from an identification problem. It is shown how to reparameterize the model in terms of freely varying parameters, to avoid this problem. It is shown how to conduct inference and how to construct distribution forecasts.
Treatment of feline lymphoma using a 12‐week, maintenance‐free combination chemotherapy protocol in 26 cats
Authors: Limmer S. , Eberle N. , Nerschbach V. , Nolte I. , Betz D.
Published: February 2014

The aim of this prospective clinical trial was to investigate the efficacy and toxicity of a short‐term, maintenance‐free chemotherapy protocol in feline lymphoma. Twenty‐six cats with confirmed diagnosis of high‐/intermediate‐grade lymphoma were treated with a 12‐week protocol consisting of cyclic administration ofl‐asparaginase, vincristine, cyclophosphamide, doxorubicin and prednisolone. Complete (CR) and partial remission (PR) rates were 46 and 27%, respectively. Median duration of firstCRwas 394 days compared with a medianPRduration of 41 days. No factor was identified to significantly influence the likelihood to reachCR. Overall survival amounted to 78 days (range: 9–2230 days). Median survival inCRcats was 454 days and inPRcats was 82 days. Toxicosis was mainly low grade with anorexia seen most frequently. In cats achievingCR, maintenance‐free chemotherapy may be sufficient to attain long‐term remission and survival. Factors aiding in prognosticating the likelihood forCR, strategies enhancing response and targeting chemotherapy‐induced anorexia need to be identified in future.
Philippine English revisited
Authors: PEFIANCO MARTIN ISABEL
Published: February 2014

In this paper, I argue that the Three Circles Model of Kachru, a profoundly influential and instructive model for approaching the varieties of Englishes across the world, might be re‐examined in the context of the Philippines, in order to better capture the sociolinguistic realities of Outer Circle speakers of English. Using the Philippines as an example, I hope to demonstrate that within the Outer Circle that is the Philippines, there are circles of English as well. While some educated Filipino scholars have rejected the dominance of American English in the Philippines, others remain ambivalent about the place of Philippine English in such domains such as English language teaching. And for a majority of the Filipinos, to whom English of whatever variety remains elusive and inaccessible, English is irrelevant. Thus, the situation for the Philippines is that there is an Inner Circle, an Outer Circle, and an Expanding circle of English. By presenting the Philippine experience of English through this framework of ‘circles within circles,’ I hope to offer a more nuanced position on the acceptability of Philippine English among Filipino users of the language.
English naming and code‐mixing in Thai mass media
Authors: SNODIN NAVAPORN SANPRASERT
Published: February 2014

This paper examines the increasing role of English in the modern day mass media of Thailand, and the rapid increase in the use of English names and code‐mixing since the turn of the century. It provides a description of the present day phenomena of English naming and code‐mixing in both the broadcast and print media of Thailand. The paper also provides an assessment of the impact of English, which explains the adoption of English names or English‐Thai hybrids, and the assimilation of Western cultural dimensions by the indigenous population of Thailand, who use English as a foreign language. The intended audience of the mass media in this study are Thais. The data supports knowledge about the widespread use of English among users in the Expanding Circle, and about world Englishes as mixed codes that are used among people who share a common language, other than English, for their intranational communication.
Developing an Experimental Database for Mitral Valve Computational Modeling, Surgical Repair, and Device Evaluation
Authors: Rabbah Jean-Pierre M. , Saikrishnan Neelakantan , Siefert Andrew W. , Yoganathan Ajit P.
Published: February 2014

Numerical models of the heart’s mitral valve are being used to study valve biomechanics, facilitate predictive surgical planning, and are used in the design and development of repair devices. These models have evolved from simple two-dimensional approximations to complex three-dimensional fully coupled fluid structure interaction models. However, to date these models lack direct one-to-one experimental validation. Moreover, as computational solvers vary considerably based on researcher implementation, experimental benchmark data are critically important to ensure model accuracy. To this end, a multi-modality in-vitro pulsatile left heart simulator was used to establish a database of geometric and hemodynamic boundary conditions coupled with resultant valvular and fluid mechanics.
Experimental Platforms for Validation of Computational Approaches to Simulating Cardiovascular Flows
Authors: Saikrishnan Neelakantan , Rabbah Jean-Pierre , Gunning Paul , Okafor Ikay , Santhanakrishnan Arvind , McNamara Laoise , Yoganathan Ajit P.
Published: February 2014

This paper describes three different versions of left heart simulators that have been developed at the Cardiovascular Fluid Mechanics Laboratory at Georgia Institute of Technology, specifically designed to provide high fidelity experimental datasets necessary for rigorous validation of computational tools. These systems are capable of simulating physiological and pathological flow, pressure and geometric conditions, and can be investigated using a variety of experimental tools to measure relevant biomechanical quantities. The development of such robust simulators is a critical step in ensuring applicability of patient specific computational tools.
Effect of Experimental Conditions on Estimation of Compressive Stiffness of Spinal Cages
Authors: Kim Yoon Hyuk , Choi Dae Kyung , Kim Kyungsoo
Published: February 2014

Recently, novel polymers including polyetheretherketone (PEEK) and carbon fiber reinforced polymer (CFRP) have been used for spinal implants. Because the in vitro experimental test uses metal blocks with different material properties from those of polymer cages in standard test protocols for prediction of the mechanical performance, it is necessary to analyze the influence of various experimental conditions, such as the material of the blocks. In this study, the compressive stiffness of spinal cages was estimated for different materials (PEEK, CFRP, and titanium) and shapes (open and closed) under simulations of the mechanical experimental tests and the in vivo situation using finite element analysis. The stiffness percentages of the open cage, when the stiffness in Case 1 was assumed 100%, were changed from 37%, 57% and 67% to 301%, 440% and 499% in the PEEK, CFRP and titanium materials, respectively by loading conditions. The stiffness was affected by shapes of cage as well as experimental conditions such as the load application method or fixation block. Hence, it may be necessary to consider the experimental conditions during in vitro mechanical tests for the stiffness estimation of spinal cages made of novel polymers to obtain results relevant for an in vivo situation.
Statistical Shape Modeling and Population Analysis of the Aortic Root of TAVI Patients
Authors: Bosmans Bart , Huysmans Toon , Wirix-Speetjens Roel , Verschueren Peter , Sijbers Jan , Bosmans Johan , Vander Sloten Jos
Published: February 2014

Transcatheter aortic valve implantation (TAVI) is a relatively new technique offering a treatment option to patients for whom an open-heart surgery represents a high risk of fatality. Due to the percutaneous delivery method of this treatment, there are challenges associated. In this technique the native aortic valve is not resected, making it difficult to judge the required size of the implant and making the sealing unpredictable. After implantation, 50% of the patients suffer from at least a mild degree of leakage alongside the implant, also known as paravalvular regurgitation [1].
Energy Based Model to Predict the Tissue-Needle Interaction Mechanics of Active Surgical Needles
Authors: Datla Naresh V. , Hutapea Parsaoran
Published: February 2014

Needle insertion is a common surgical technique used in diagnosis (e.g. biopsy) and prognosis (e.g. brachytherapy) of several diseases. The success of such procedures highly depends on the accuracy of needle placement to target locations. Accuracy of the needle placement is presently limited due to movement of tissue, inability to control needle deflection, and inaccessibility of image monitoring techniques. These limitations are being addressed by using active (or smart) needles (e.g. see Fig. 1) that can maneuver within the tissue with the aid of actuators attached to the needle body [1–3]. However, in these studies, active needles were studied in air but not inside the tissue where they are supposed to be used. Therefore, to develop active needles that are feasible for clinical applications, it is necessary to understand the mechanics of active needles within the tissue.
Oxygen plasma immersion ion implantation treatment to enhance data retention of tungsten nanocrystal nonvolatile memory
Authors: Wang Jer-Chyi , Chang Wei-Cheng , Lai Chao-Sung , Chang Li-Chun , Ai Chi-Fong , Tsai Wen-Fa
Published: February 2014

Data retention characteristics of tungsten nanocrystal (W-NC) memory devices using an oxygen plasma immersion ion implantation (PIII) treatment are investigated. With an increase of oxygen PIII bias voltage and treatment time, the capacitance–voltage hysteresis memory window is increased but the data retention characteristics become degraded. High-resolution transmission electron microscopy images show that this poor data retention is a result of plasma damage on the tunneling oxide layer, which can be prevented by lowering the bias voltage to 7 kV. In addition, by using the elevated temperature retention measurement technique, the effective charge trapping level of the WO3 film surrounding the W-NCs can be extracted. This measurement reveals that a higher oxygen PIII bias voltage and treatment time induces more shallow traps within the WO3 film, degrading the retention behavior of the W-NC memory.
Modification by UV radiation of the surface of thin films based on collagen extracted from fish scales
Authors: Sionkowska Alina , Kozłowska Justyna , Lazare Sylvain
Published: February 2014

Collagen was extracted from fish scales (Esox lucius) through demineralization process. Thin films by solvent evaporation from collagen extracted from fish scales were prepared. The surface of thin films made of fish scales collagen was modified by ultraviolet (UV)-irradiation with the wavelength λ = 254 nm. The amino acid composition of the Esox lucius scale collagen was analyzed before and after UV-irradiation by means of high-pressure liquid chromatography. The surface properties of films were investigated using the technique of atomic force microscopy (AFM) and by means of contact angle measurements allowing the calculation of surface free energy. Measurements of the contact angle for diiodomethane (D) and glycerol (G) on the surface of fish collagen films were made and surface free energy was calculated. The structure of collagen before and after UV-irradiation was studied using Fourier-transform infrared spectroscopy. It was found that after UV-irradiation the amount of all amino acids present in collagen molecule decreased. It was found also that the contact angle and the surface free energy were altered by UV-irradiation of collagen film. AFM showed that the surface roughness of collagen films was also altered by UV-irradiation. UV-irradiation caused the decrease of surface roughness due to photochemical processes, which occurred in the top layer of collagen film. The formation of collagen fibrils after solvent evaporation was observed using AFM. The diameter of collagen fibrils was bigger for irradiated collagen film than the diameter of collagen fibrils before UV-irradiation.
Three‐dimensional x‐ray fluorescence mapping of a gold nanoparticle‐loaded phantom
Authors: Ren Liqiang , Wu Di , Li Yuhua , Wang Ge , Wu Xizeng , Liu Hong
Published: February 2014

Purpose

: X‐ray fluorescence (XRF) is a promising technique with sufficient specificity and sensitivity for identifying and quantifying features in small samples containing high atomic number (Z) materials such as iodine, gadolinium, and gold. In this study, the feasibility of applying XRF to early breast cancer diagnosis and treatment is studied using a novel approach for three‐dimensional (3D) x‐ray fluorescence mapping (XFM) of gold nanoparticle (GNP)‐loaded objects in a physical phantom at the technical level.

Methods

: All the theoretical analysis and experiments are conducted under the condition of using x‐ray pencil beam and a compactly integrated x‐ray spectrometer. The penetrability of the fluorescence x‐rays from GNPs is first investigated by adopting a combination of BR12 with 70 mm/50 mm in thickness on the excitation/emission path to mimic the possible position of tumor goldin vivo. Then, a physical phantom made of BR12 is designed to translate in 3D space with three precise linear stages and subsequently the step by step XFM scanning is performed. The experimental technique named as background subtraction is applied to isolate the gold fluorescence from each spectrum obtained by the spectrometer. Afterwards, the attenuations of both the incident primary x‐ray beam with energies beyond the gold K‐edge energy (80.725 keV) and the isolated gold Kα fluorescence x‐rays (65.99 −69.80 keV) acquired after background subtraction are well calibrated, and finally the unattenuated Kα fluorescence counts are used to realize mapping reconstruction and to describe the linear relationship between gold fluorescence counts and corresponding concentration of gold solutions.

Results

: The penetration results show that the goldKα fluorescence x‐rays have sufficient penetrability for this phantom study, and the reconstructed mapping results indicate that both the spatial distribution and relative concentration of GNPs within the designed BR12 phantom can be well identified and quantified.

Conclusions

: Although the XFM method in this investigation is still studied at the technical level and is not yet practical for routinein vivo mapping tasks with GNPs, the current penetrability measurements and phantom study strongly suggest the feasibility to establish and develop a 3D XFM system.
Suitability of markerless EPID tracking for tumor position verification in gated radiotherapy
Authors: Serpa Marco , Baier Kurt , Cremers Florian , Guckenberger Matthias , Meyer Juergen
Published: February 2014

Purpose:

To maximize the benefits of respiratory gated radiotherapy (RGRT) of lung tumors real‐time verification of the tumor position is required. This work investigates the feasibility of markerless tracking of lung tumors during beam‐on time in electronic portal imaging device (EPID) images of the MV therapeutic beam.

Methods:

EPID movies were acquired at ∼2 fps for seven lung cancer patients with tumor peak‐to‐peak motion ranges between 7.8 and 17.9 mm (mean: 13.7 mm) undergoing stereotactic body radiotherapy. The external breathing motion of the abdomen was synchronously measured. Both datasets were retrospectively analyzed inPortalTrack, an in‐house developed tracking software. The authors define a three‐step procedure to run the simulations: (1) gating window definition, (2) gated‐beam delivery simulation, and (3) tumor tracking. First, an amplitude threshold level was set on the external signal, defining the onset of beam‐on/‐off signals. This information was then mapped onto a sequence of EPID images to generate stamps of beam‐on/‐hold periods throughout the EPID movies in PortalTrack, by obscuring the frames corresponding to beam‐off times. Last, tumor motion in the superior‐inferior direction was determined on portal images by the tracking algorithm during beam‐on time. The residual motion inside the gating window as well as target coverage (TC) and the marginal target displacement (MTD) were used as measures to quantify tumor position variability.

Results:

Tumor position monitoring and estimation from beamˈs‐eye‐view images during RGRT was possible in 67% of the analyzed beams. For a reference gating window of 5 mm, deviations ranging from 2% to 86% (35% on average) were recorded between the reference and measured residual motion. TC (range: 62%–93%; mean: 77%) losses were correlated with false positives incidence rates resulting mostly from intra‐/inter‐beam baseline drifts, as well as sudden cycle‐to‐cycle fluctuations in exhale positions. Both phenomena can lead to considerable deviations (with MTD values up to a maximum of 7.8 mm) from the intended tumor position, and in turn may result in a marginal miss. The difference between tumor traces determined within the gating window against ground truth trajectory maps was 1.1 ± 0.7 mm on average (range: 0.4–2.3 mm).

Conclusions:

In this retrospective analysis of motion data, it is demonstrated that the system is capable of determining tumor positions in the plane perpendicular to the beam direction without the aid of fiducial markers, and may hence be suitable as an online verification tool in RGRT. It may be possible to use the tracking information to enable on‐the‐fly corrections to intra‐/inter‐beam variations by adapting the gating window by means of a robotic couch.
Towards clinical prostate ultrasound elastography using full inversion approach
Authors: Mousavi Seyed Reza , Sadeghi‐Naini Ali , Czarnota Gregory J. , Samani Abbas
Published: February 2014

Purpose:

Various types of cancers including prostate cancer are known to be associated with biological changes that lead to tissue stiffening. Digital rectal examination is based on manually palpating the prostate tissue via the rectum. This test lacks sufficient accuracy required for early diagnosis which is necessary for effective management of prostate cancer. To develop an effective prostate cancer diagnostic technique, the authors propose an imaging technique that maps the distribution of the relative prostate tissueˈs elasticity modulus. Unlike digital rectal examination, this technique is quantitative, capable of accurately detecting small prostate lesions that cannot be sensed by manual palpation, and its accuracy is independent of the physicianˈs experience.

Methods:

The proposed technique is a quasistatic elastography technique which uses ultrasound imaging to acquire tissue displacements resulting from transrectal ultrasound mechanical stimulation. The system involves a standard ultrasound imaging unit with accessibility to its radiofrequency data. The displacements are used as data for the tissue elasticity reconstruction. This reconstruction does not require tissue segmentation and is based on physics governing tissue mechanics. It is formulated using an inverse problem framework where elastic tissue deformation equations are fully inverted using an iterative scheme where each iteration involves stress calculation followed by elastic modulus updating until convergence is achieved.In silico and tissue mimicking phantom studies were conducted to validate the proposed technique, followed by a clinical pilot study involving two prostate cancer patients with whole‐mount histopathology analysis on prostatectomy specimens to confirm a cancer location.

Results:

The phantom studies demonstrated robustness and reasonably high accuracy of the proposed method. Obtained Youngˈs modulus ratios indicated reconstruction errors of less than 12%. Reconstructed elastic modulus images of the two clinical cases were compared to whole‐mount histopathology slides where cancerous areas were identified. This comparison indicated marked tissue stiffening in the cancer area with reasonably accurate consistency observed between cancerous lesions identified by histopathology and high stiffness areas of the elastography images.

Conclusions:

Results obtained from the phantom and patient studies indicate that the proposed method is reasonably accurate for detecting cancerous lesions. The proposed system does not require any additional hardware attachment for mechanical stimulation or data acquisition while the elasticity reconstruction algorithm can be easily implemented, leading to a low cost system that can be potentially utilized as an effective clinical tool for prostate cancer diagnosis.
Interaction of Radiation with Matter.
Authors: Zhang Qinghui
Published: February 2014

Interaction of Radiation with Matter. Nikjoo H., Uehara S., Emfietzoglou D., CRC Press, Taylor & Francis Group, Boca Raton, FL, 2012. $135.95. ISBN: 978‐1‐43985‐357‐3, 364 pp. (hardcover).
Frequency tuning of hearing in the beluga whale: Discrimination of rippled spectra
Authors: Sysueva Evgenia V. , Nechaev Dmitry I. , Popov Vladimir V. , Supin Alexander Ya.
Published: February 2014

Frequency tuning was measured in the beluga whale (Delphinapterus leucas) using rippled-noise test stimuli in conjunction with an auditory evoked potential (AEP) technique. The test stimulus was a 2-octave-wide rippled noise with frequency-proportional ripple spacing. The rippled-noise signal contained either a single reversal or rhythmic (1-kHz rate) reversals of the ripple phase. Single or rhythmic phase reversals evoked, respectively, a single auditory brainstem response (ABR) or a rhythmic AEP sequence—the envelope following response (EFR). The response was considered as an indication of resolvability of the ripple pattern. The rhythmic phase-reversal test with EFR recording revealed higher resolution than the single phase-reversal test with single ABR recording. The limit of ripple-pattern resolution with the single phase-reversal test ranged from 17 ripples per octave (rpo) at 32 kHz to 24 rpo at 45 to 64 kHz; for the rhythmic phase-reversal test, the limit ranged from 20 to 32 rpo. An interaction model of a ripple spectrum with frequency-tuned filters suggests that the ripple-pattern resolution limit of 20 to 32 rpo requires a filter quality Q of 29 to 46. Possible causes of disagreement of these estimates with several previously published data are discussed.
The Partition of Unity Finite Element Method for the simulation of waves in air and poroelastic media
Authors: Chazot Jean-Daniel , Perrey-Debain Emmanuel , Nennig Benoit
Published: February 2014

Recently Chazot et al. [J. Sound Vib. 332, 1918–1929 (2013)] applied the Partition of Unity Finite Element Method for the analysis of interior sound fields with absorbing materials. The method was shown to allow a substantial reduction of the number of degrees of freedom compared to the standard Finite Element Method. The work is however restricted to a certain class of absorbing materials that react like an equivalent fluid. This paper presents an extension of the method to the numerical simulation of Biot's waves in poroelastic materials. The technique relies mainly on expanding the elastic displacement as well as the fluid phase pressure using sets of plane waves which are solutions to the governing partial differential equations. To show the interest of the method for tackling problems of practical interests, poroelastic-acoustic coupling conditions as well as fixed or sliding edge conditions are presented and numerically tested. It is shown that the technique is a good candidate for solving noise control problems at medium and high frequency.
Dirac cone dispersion of acoustic waves in plates without phononic crystals
Authors: Maznev A. A.
Published: February 2014

Lamb waves in elastic plates exhibit Dirac-like cone dispersion at zero wavevector at the points of accidental degeneracy between longitudinal and transverse thickness resonances. The Lamb mode dispersion can be fine-tuned to yield a conical point by coating a plate with a layer of a different material and varying the thickness of the latter. Similarities and differences with respect to Dirac-like cone dispersion in phononic crystals and possible observable effects are discussed.
Transient characteristics and stability analysis of standing wave thermoacoustic-piezoelectric harvesters
Authors: Nouh Mostafa , Aldraihem Osama , Baz Amr
Published: February 2014

Standing wave thermoacoustic-piezoelectric (TAP) energy harvesters convert thermal energy, such as solar or waste heat energy, directly into electrical energy without the need for any moving components. The input thermal energy generates a steep temperature gradient along a porous medium called “stack.” At a critical threshold of the temperature gradient, self-sustained acoustic waves are developed inside an acoustic resonator. The associated pressure fluctuations impinge on a piezoelectric diaphragm, placed at the end of the resonator, to generate electricity. The behavior of this multi-field system is modeled using the electrical analogy approach. The developed model combines the descriptions of the acoustic resonator and the stack with the characteristics of the piezoelectric diaphragm. The equivalent electric network is analyzed to determine the system's stability and predict the temperature gradient necessary to developing self-sustained oscillations inside the harvester. The developed network is utilized also to investigate the transient performance of the harvester by employing the network theory and Simulation Program with Integrated Circuit Emphasis software package. The established stability boundaries are validated against the predictions of the root locus technique. Furthermore, the obtained results are compared with experimental results extracted from testing a prototype of the harvester. The developed approach presents an innovative tool for the design of TAP energy harvesters.
Towed body measurements of flow noise from a turbulent boundary layer under sea conditions
Authors: Abshagen J. , Nejedl V.
Published: February 2014

Results from an underwater experiment under sea conditions on flow noise beneath a flat-plate turbulent boundary layer are presented. The measurements were performed with a towed body at towing speeds U=2.3,…,6.1 m/s and depths h=−150,…,−100 m. Flow noise is measured with a linear array of equally spaced hydrophones (Δx=70 mm) that is orientated in streamwise direction and embedded within a laterally attached flat plate. In order to separate flow noise from ocean ambient noise and other acoustical noise sources wavenumber-frequency filtering is applied. The (nondimensionalized) spectral power density of flow noise Φ(ω) ⟨U∞⟩/ (⟨δ∗⟩ (1/2ρ ⟨U∞⟩)2) is found to scale like (ω⟨δ∗⟩/⟨U∞⟩)−4.3 in a wide frequency range at higher towing speeds. Here, ω, ⟨δ∗⟩, and ⟨U∞⟩ denote frequency, boundary layer displacement thickness, and potential flow velocity in the array region, respectively. Potential flow velocity is estimated from numerical simulations around a symmetrical, two-dimensional body with a semi-elliptical nose. Evidence is given that a χ2-(Tsallis) superstatistics provides a reasonable representation of the probability distribution function of flow noise at higher towing speeds.
Possible second-order nonlinear interactions of plane waves in an elastic solid
Authors: Korneev V. A. , Demčenko A.
Published: February 2014

There exist ten possible nonlinear elastic wave interactions for an isotropic solid described by three constants of the third order. All other possible interactions out of 54 combinations (triplets) of interacting and resulting waves are prohibited, because of restrictions of various kinds. The considered waves include longitudinal and two shear waves polarized in the interacting plane and orthogonal to it. The amplitudes of scattered waves have simple analytical forms, which can be used for experimental setup and design. The analytic results are verified by comparison with numerical solutions of initial equations. Amplitude coefficients for all ten interactions are computed as functions of frequency for polyvinyl chloride, together with interaction and scattering angles. The nonlinear equation of motion is put into a general vector form and can be used for any coordinate system.
A method to compute the radiated sound power based on mapped acoustic radiation modes
Authors: Wu Haijun , Jiang Weikang , Zhang Yilin , Lu Wenbo
Published: February 2014

Application of modal expansion approach for the exterior acoustic field has drawn wide research interests in recent years. This is primarily due to the acoustic radiation modes (ARM) that can diagonalize the impedance matrix, hence significantly simplifying the computation of radiated sound power. The orthogonal ARM are typically calculated via a standard eigenvalue analysis of the impedance matrix, which normally leads to numerical difficulties especially for wideband frequency and large scale problems. In this paper, a theory of mapped ARM is proposed to avoid the cumbersome computation of ARM for convex structures. A mapping relationship between the ARM on the surface of an equivalent spherical source and the mapped ARM on the surface of a convex structure is obtained based on the equivalent source method, multipole expansion method, and boundary integral method. Furthermore, analytical expressions for the radiated sound power of structures vibrating in its mapped ARM as well as that of spheres are derived. Finally, a simple method is proposed to approximate the radiated sound power based on the modal decomposition method and the mapping relationship. Numerical simulations are conducted to validate the accuracy and efficiency of the proposed approach, and different vibrating structures with various geometries are considered. Results demonstrate that the proposed methodology for calculating the radiated sound power of convex structures is very efficient and accurate as compared with the traditional approach.
Testing, correcting, and extending the Woodworth model for interaural time difference
Authors: Aaronson Neil L. , Hartmann William M.
Published: February 2014

The Woodworth model and formula for interaural time difference is frequently used as a standard in physiological and psychoacoustical studies of binaural hearing for humans and other animals. It is a frequency-independent, ray-tracing model of a rigid spherical head that is expected to agree with the high-frequency limit of an exact diffraction model. The predictions by the Woodworth model for antipodal ears and for incident plane waves are here compared with the predictions of the exact model as a function of frequency to quantify the discrepancy when the frequency is not high. In a second calculation, the Woodworth model is extended to arbitrary ear angles, both for plane-wave incidence and for finite point-source distance. The extended Woodworth model leads to different formulas in six different regions defined by ear angle and source distance. It is noted that the characteristic cusp in Woodworth's well-known function comes from ignoring the longer of the two paths around the head in circumstances when the longer path is actually important. This error can be readily corrected.
Airborne sound propagation over sea during offshore wind farm piling
Authors: Van Renterghem T. , Botteldooren D. , Dekoninck L.
Published: February 2014

Offshore piling for wind farm construction has attracted a lot of attention in recent years due to the extremely high noise emission levels associated with such operations. While underwater noise levels were shown to be harmful for the marine biology, the propagation of airborne piling noise over sea has not been studied in detail before. In this study, detailed numerical calculations have been performed with the Green's Function Parabolic Equation (GFPE) method to estimate noise levels up to a distance of 10 km. Measured noise emission levels during piling of pinpiles for a jacket-foundation wind turbine were assessed and used together with combinations of the sea surface state and idealized vertical sound speed profiles (downwind sound propagation). Effective impedances were found and used to represent non-flat sea surfaces at low-wind sea states 2, 3, and 4. Calculations show that scattering by a rough sea surface, which decreases sound pressure levels, exceeds refractive effects, which increase sound pressure levels under downwind conditions. This suggests that the presence of wind, even when blowing downwind to potential receivers, is beneficial to increase the attenuation of piling sound over the sea. A fully flat sea surface therefore represents a worst-case scenario.
Auditory and tactile gap discrimination by observers with normal and impaired hearing
Authors: Desloge Joseph G. , Reed Charlotte M. , Braida Louis D. , Perez Zachary D. , Delhorne Lorraine A. , Villabona Timothy J.
Published: February 2014

Temporal processing ability for the senses of hearing and touch was examined through the measurement of gap-duration discrimination thresholds (GDDTs) employing the same low-frequency sinusoidal stimuli in both modalities. GDDTs were measured in three groups of observers (normal-hearing, hearing-impaired, and normal-hearing with simulated hearing loss) covering an age range of 21–69 yr. GDDTs for a baseline gap of 6 ms were measured for four different combinations of 100-ms leading and trailing markers (250–250, 250–400, 400–250, and 400–400 Hz). Auditory measurements were obtained for monaural presentation over headphones and tactile measurements were obtained using sinusoidal vibrations presented to the left middle finger. The auditory GDDTs of the hearing-impaired listeners, which were larger than those of the normal-hearing observers, were well-reproduced in the listeners with simulated loss. The magnitude of the GDDT was generally independent of modality and showed effects of age in both modalities. The use of different-frequency compared to same-frequency markers led to a greater deterioration in auditory GDDTs compared to tactile GDDTs and may reflect differences in bandwidth properties between the two sensory systems.
Adaptive calibration of a three-microphone system for acoustic waveguide characterization under time-varying conditions
Authors: van Walstijn Maarten , de Sanctis Giovanni
Published: February 2014

The pressure and velocity field in a one-dimensional acoustic waveguide can be sensed in a non-intrusive manner using spatially distributed microphones. Experimental characterization with sensor arrangements of this type has many applications in measurement and control. This paper presents a method for measuring the acoustic variables in a duct under fluctuating propagation conditions with specific focus on in-system calibration and tracking of the system parameters of a three-microphone measurement configuration. The tractability of the non-linear optimization problem that results from taking a parametric approach is investigated alongside the influence of extraneous measurement noise on the parameter estimates. The validity and accuracy of the method are experimentally assessed in terms of the ability of the calibrated system to separate the propagating waves under controlled conditions. The tracking performance is tested through measurements with a time-varying mean flow, including an experiment conducted under propagation conditions similar to those in a wind instrument during playing.