bluuebunny/crossref_metadata_2025 huggingface dataset:
Cultural Influences on Entrepreneurial Orientation: The Impact of National Culture on Risk Taking and Proactiveness in SMEs
Authors: Kreiser Patrick M. , Marino Louis D. , Dickson Pat , Weaver K. Mark
Published: June 2010

This study utilizes data from 1,048 firms in six countries to assess the impact of national culture and certain institutions that are representative of national culture on two key dimensions of entrepreneurial orientation: risk taking and proactiveness. Eight hypotheses are developed specifying the expected relationships between four cultural dimensions and levels of risk taking and proactiveness within SMEs. Additionally, two hypotheses are developed to explore between–country differences in the relationship between risk taking and proactiveness and a range of institutional variables. Uncertainty avoidance and power distance are both found to have a significant negative influence on risk taking; uncertainty avoidance, individualism, and power distance are found to negatively influence proactive firm behaviors. A number of institutional factors are also found to be significantly linked to between–country differences in both risk taking and proactive behaviors. This research contributes to existing theories of national culture by suggesting that the various dimensions of cultural values and several of the institutions that are representative of national culture impact the willingness of entrepreneurial firms to display risk taking and proactive behaviors.
Cryoballoon Pulmonary Vein Isolation Supported by Intracardiac Echocardiography: Integration of a Nonfluoroscopic Imaging Technique in Atrial Fibrillation Ablation
Authors: NÖLKER GEORG , HEINTZE JOHANNES , GUTLEBEN KLAUS‐JÜRGEN , MUNTEAN BOGDAN , PÜTZ VANESSA , YALDA AMEERA , VOGT JÜRGEN , HORSTKOTTE DIETER
Published: June 2010

Intracardiac Echo Supported Cryoballoon Ablation. Introduction: Cryoballoon ablation has been adopted for pulmonary vein (PV) isolation (PVI) in many centers. Complete occlusion of PV by an adequately sized balloon is crucial for effectiveness of cryoenergy delivery. The aim of this study was to evaluate intracardiac echocardiography (ICE) as an alternative imaging technique compared to angiographic imaging in cryoballoon PVI.

Methods and Results:
A total of 75 PVs were treated in 22 patients (61 ± 13 years, 17 male) undergoing PV cryoballoon ablation for drug refractory paroxysmal atrial fibrillation. Decision for an adequate balloon size was based on diameters of the PV antra assessed by ICE and PV angiography. Per PV 2.4 ± 0.4 cryoenergy pulses were applied. Decision for the balloon size was similar either based upon angiography or on ICE. A single 23 or 28 mm balloon was chosen in 10 and 3 patients, respectively. Two different sized balloons were used in 9 patients. PVI was evaluated after 2 cryoenergy applications. Total occlusion of the PV confirmed by ICE color flow Doppler (CFD) during ablation predicted successful PVI in 70 of 75 (93%) and unsuccessful PVI in 8 of 8 (100%). PV flow registered by pulsed wave Doppler at the PV ostium pre‐ and postablation was 0.48 ± 0.10 and 0.51 ± 0.12 m/s, respectively (n.s.). PVI was finally confirmed by entrance block in all PVs. No procedural complications occurred.

Conclusions:
ICE is a feasible novel imaging technique in cryoballoon ablation procedures. It allows decision for adequate balloon size, exact balloon placement, prediction of acute ablation success, and excludes acute narrowing of PV ostia. (J Cardiovasc Electrophysiol, Vol. 21, pp. 1325‐1330, December 2010)
New Annular Tissue Doppler Markers of Pulmonary Hypertension
Authors: López‐Candales Angel , Edelman Kathy , Gulyasy Beth , Candales Maria Dolores
Published: June 2010

Background: Tissue Doppler imaging (TDI) of mitral (MA) and tricuspid annulus (TA) events characterizes systolic and diastolic properties of each respective ventricle. However, the effect of chronic pulmonary hypertension (cPH) on these TDI annular events has not been well described. Methods: Measurements of right ventricular (RV) performance with TDI of the lateral mitral and tricuspid annuli, to measure isovolumic contraction (IVC) and systolic (S) signals were recorded from 50 individuals without PH and from 50 patients with cPH. To avoid confounding variables, all patients had normal left ventricular ejection fraction and were in normal sinus rhythm at the time of the examination. Results: As expected, markers of RV systolic performance were markedly reduced while LV systolic function remained largely unaffected in cPH patients when compared to patients without PH. TDI interrogation of the MA revealed lengthening of the time interval between IVC and systolic signal (70 ± 17 msec) when compared to individuals without PH (43 ± 8 msec; P < 0.0001). In contrast, cPH markedly shortened the time interval between IVC and the TA systolic signal (34 ± 12 msec) when compared to individuals without PH (65 ± 17 msec; P < 0.0001). Conclusions: cPH lengthens time interval between the IVC and the MA systolic signal while shortening this same interval when the TA is interrogated with TDI; reflecting the potential influence that cPH exerts in biventricular performance. Whether measuring these intervals be routinely used in the follow‐up of cPH patients will require further study. (Echocardiography 2010;27:969‐976)
Effects of Atorvastatin and Lisinopril on Endothelial Dysfunction in Patients with Behçet's Disease
Authors: Inanc Mehmet Tugrul , Kalay Nihat , Heyit Turgun , Ozdogru Ibrahim , Kaya Mehmet Gungor , Dogan Ali , Duran Mustafa , Kasapkara Haci Ahmet , Gunebakmaz Ozgur , Borlu Murat , Yarlıoglues Mikail , Oguzhan Abdurrahman
Published: June 2010

Objective: Behçet's disease is a chronic inflammatory vasculitis. Vascular involvement is one of the major complications of Behçet's disease, during the course of the disease. Previous studies showed that ACE inhibitors and statins may improve endothelial functions in endothelial dysfunction. The aim of our study is to compare the effects of atorvastatin and lisinopril to placebo on endothelial dysfunction in patients with Behçet's disease. Patients and methods: We prospectively studied 92 (48 female) Behçet's patients who were diagnosed according to the International Study Group criteria. Endothelial dysfunction was evaluated by brachial artery flow‐mediated dilatation (FMD) method using high‐resolution vascular ultrasound device at baseline and after for 3‐month therapy. Patients were consecutively randomized into three groups as (atorvastatin (n = 31), lisinopril (n = 31), and placebo groups (n = 30). Patients in atorvastatin group received 20 mg atorvastatin, lisinopril group received 10 mg lisinopril per day, and placebo group received placebo per day for 3 months. Results: The baseline characteristics of patients were similar among three groups; however, high‐sensitive C‐reactive protein (hs‐CRP) levels were lower in atorvastatin group than placebo group. A significant improvement in FMD was observed in both atorvastatin (5.0 ± 1.4 vs. 12.8 ± 3.6%, P < 0.001) and lisinopril groups (5.0 ± 1.2 vs. 11.4 ± 5.0%, P < 0.001). Partial significant enhancement was observed in placebo group (4.9 ± 1.1% vs. 5.7 ± 1.0, P = 0.002). However, it was lower than the cutoff value for endothelial dysfunction. Conclusion: These findings suggest that atorvastatin and lisinopril improve endothelial functions in Behçet's disease patients. However, large studies are needed to determine the long‐term effects of atorvastatin and lisinopril therapy. (Echocardiography 2010;27:997‐1003)
Transesophageal Echocardiography Guided Percutaneous Closure of Secundum Atrial Septal Defects
Authors: Lerakis Stamatios , Babaliaros Vasilis C.
Published: June 2010

(Echocardiography 2010,27:724‐727)
Giant Aortic Aneurysm: Alarming Expansion after Redo AVR
Authors: Sidhu Maninder S. , Singh Harinder Pal , Chopra Arun K. , Chopra Suruchi , Goel Pankaj , Kapila Deepak , Anand Manan , Sidhu Shailpreet , Gupta Sharad
Published: June 2010

(Echocardiography 2010;27:E73‐E74)
Low Loss, High Tunability of Ba0.4Sr0.6TiO3–Mg3B2O6 Microwave Composite Ceramics
Authors: Zhang Qiwei , Zhai Jiwei , Yao Xi
Published: June 2010

Phase structure, microstructure, and microwave dielectric properties of Ba0.4Sr0.6TiO3–Mg3B2O6 composite ceramics fabricated by solid‐state reaction were investigated. The results show that the composite ceramics sintered at only 1100°C exhibited promising microwave properties. The dielectric constant can be adjusted in the range from 326 to 90, while maintaining a relatively high tunability from 21% to 11% under a direct current electric field of 60 kV/cm and Q values more than 200 in the gigahertz frequency region.
Role Stress, Exhaustion, and Satisfaction: A Cross‐Lagged Structural Equation Modeling Approach Supporting Hobfoll's Loss Spirals
Authors: ÖRtqvist Daniel , Wincent Joakim
Published: June 2010

This study applies Hobfoll's notion of loss spirals to argue for a reciprocal relationship between role stress and 2 of its most commonly studied consequences: exhaustion and satisfaction. By means of structural equation modeling and a cross‐lagged design of 116 business managers, the researchers found support for a relationship between role stress and exhaustion. They also found that satisfaction influences role stress, a relationship that the existing literature has not examined. The study contributes a more complex understanding of the relationship between role stress and its modeled outcomes than has been achieved previously.
Relationship Between Job Characteristics and Attitudes: A Study of Temporary Employees
Authors: Slattery Jeffrey P. , Selvarajan T.T. , Anderson John E. , Sardessai Ron
Published: June 2010

We examine the relationship between job characteristics and employee attitudes in the context of temporary employees who are assigned to work at the client organizations but are formally employed by a temporary agency. Based on the rationale provided by social exchange and social identity theories, we hypothesized that job characteristics would be related to job satisfaction, organizational commitment, and turnover intention in regard to both the client organization and the temporary agency. Results based on data collected from a large temporary agency supported all hypothesized relationships in regard to the client organization, and most hypothesized relationships in regard to the temporary agency. We discuss implications of these findings for research and the practice of managing temporary employee attitudes.
Subjective distress predicts treatment seeking for depression, bipolar, anxiety, panic, neurasthenia and insomnia severity spectra
Authors: Angst J. , Gamma A. , Clarke D. , Ajdacic‐Gross V. , Rössler W. , Regier D.
Published: June 2010

Angst J, Gamma A, Clarke D, Ajdacic‐Gross V, Rössler W, Regier D. Subjective distress predicts treatment seeking for depression, bipolar, anxiety, panic, neurasthenia and insomnia severity spectra.

Objective:  To examine correlates of mental health treatment seeking such as gender, diagnosis, impairment, distress and mastery.

Method:  Longitudinal epidemiological data from the Zurich Study of common psychiatric syndromes, including unipolar and bipolar depression, panic, anxiety, neurasthenia and insomnia, were utilized. In longitudinal Generalized Estimating Equations, treatment seeking was regressed on measures of subjective distress and impairment, childhood family problems, mastery and number of comorbid diagnoses.

Results:  Approximately half of all treated participants across all six syndromes suffered from subthreshold disorders. Meeting full or subthreshold diagnostic criteria was associated with treatment seeking for insomnia. Being female was associated with treatment seeking for depression. The only variable highly and consistently associated with treatment seeking, across all syndromes, was subjective distress. Treated participants reported high levels of distress, work and social impairment in both diagnostic and subthreshold groups.

Conclusion:  Subjective distress may be a better indicator of treatment seeking than symptom count.
Regenerative medicine in dermatology: biomaterials, tissue engineering, stem cells, gene transfer and beyond
Authors: Dieckmann Christina , Renner Regina , Milkova Linda , Simon Jan C.
Published: June 2010

Please cite this paper as: Regenerative medicine in dermatology: biomaterials, tissue engineering, stem cells, gene transfer and beyond. Experimental Dermatology 2010; 19: 697–706.

Abstract:  The term ‘regenerative medicine’ refers to a new and expanding field in biomedical research that focuses on the development of innovative therapies allowing the body to replace, restore and regenerate damaged or diseased cells, tissues and organs. It combines several technological approaches including the use of soluble molecules, biomaterials, tissue engineering, gene therapy, stem cell transplantation and the reprogramming of cell and tissue types. Because of its easy accessibility, skin is becoming an attractive model organ for regenerative medicine. Here, we review recent developments in regenerative medicine and their potential relevance for dermatology with a particular emphasis on biomaterials, tissue engineering, skin substitutes and stem cell‐based therapies for skin reconstitution in patients suffering from chronic wounds and extensive burns.
Point scanning confocal microscopy facilitates 3D human hair follicle imaging in tissue sections
Authors: Kloepper Jennifer E. , Bíró Tamás , Paus Ralf , Cseresnyés Zoltán
Published: June 2010

Please cite this paper as: Point scanning confocal microscopy facilitates 3D human hair follicle imaging in tissue sections. Experimental Dermatology 2010; 19: 691–694.

Abstract:  Efficiency is a key factor in determining whether a scientific method becomes widely accepted in practical applications. In dermatology, morphological characterisation of intact hair follicles by traditional methods can be rather inefficient. Samples are embedded, sliced, imaged and digitally reconstructed, which can be time‐consuming. Confocal microscopy, on the other hand, is more efficient and readily applicable to study intact hair follicles. Modern confocal microscopes deliver and collect light very efficiently and thus allow high spatial resolution imaging of relatively thick samples. In this letter, we report that we successfully imaged entire intact human hair follicles using point scanning confocal microscopy. Light delivery and light‐collection were further improved by preparing the samples in 2,2′‐Thiodiethanol (TDE), thus reducing refractive index gradients. The relatively short total scan times and the high quality of the acquired 3D images make confocal microscopy a desirable method for studying intact hair follicles under normal and pathological conditions.
Episodic cerebellar dysfunction in a bichon frise: a canine case of episodic ataxia?
Authors: Hopkins A. L. , Clarke J.
Published: June 2010

A four‐year‐old neutered male bichon frise was presented for the evaluation of chronic, progressive yet episodic neurological dysfunction that was predominantly cerebellar in nature. Diagnostic testing including haematology, serum chemistry, magnetic resonance imaging, cerebrospinal fluid analysis and urine organic acid screening was normal. Trial therapies with phenobarbital, prednisone and acetazolamide were unsuccessful. Treatment with 4‐aminopyridine led to complete resolution of the signs.
Multi‐centre assessment of mycotic rhinosinusitis in dogs: a retrospective study of initial treatment success (1998 to 2008)
Authors: Sharman M. , Paul A. , Davies D. , MacKay B. , Swinney G. , Barrs V. , Arteaga A. , Robertson I. D. , Mansfield C.
Published: June 2010

Objectives: To retrospectively review the first treatment response of dogs with mycotic rhinosinusitis to commonly utilised treatment techniques.

Methods: Medical records of dogs treated for mycotic rhinosinusitis were obtained retrospectively via a manual review of the clinical databases of six veterinary referral centres for the period of January 1998 to June 2008, and first treatment outcome was evaluated. Historical and clinicopathological findings were also reviewed to evaluate their impact on treatment success or failure.

Results: There was no significant difference in first treatment outcome between treatment groups (P=0·21). When all topical treatments were considered together (n=85), 39 dogs (45·8%) had a successful first treatment. Initial treatment success was associated with a younger age (56·3versus75·8 months; P=0·02) and was 2·7 times more likely in dogs with unilateral disease, although this was not significant (P=0·07). Adjunctive therapy with systemic antifungal agents was associated with treatment failure (PÄ0·01). Fifty‐nine dogs (69·4%) responded successfully following multiple treatments.

ClinicalSignificance: Treatment of mycotic rhinosinusitis remains challenging, and multiple treatments are frequently required for adequate treatment. Reasons for first treatment failure are likely multifactorial in origin, making it difficult to predict those dogs that are likely to have a superior prognosis, regardless of the treatment type used.
ORIGINAL ARTICLE: Squamous cell carcinoma of the oral tongue in patients younger than 30 years: clinicopathologic features and outcome
Authors: Soudry E. , Preis M. , Hod R. , Hamzany Y. , Hadar T. , Bahar G. , Strenov Y. , Shpitzer T.
Published: June 2010

Clin. Otolaryngol. 2010, 35, 307–312

Objective:  To assess the possible effect of young age on clinical behaviour and survival outcome of squamous cell carcinoma of the oral tongue.

Design:  Retrospective, case control study.

Setting:  A major tertiary referral centre.

Participants:  Eighty‐five patients with oral tongue squamous cell carcinoma with at least 2 years of follow‐up.

Main outcome measurements:  Clinical and histopathological staging, disease‐free survival, disease‐specific survival and overall survival.

Results:  Eleven patients (13%) were younger than 30 years. Compared to the older patients, they had a significantly worse N stage (P = 0.041), more perineural invasion (P = 0.012), and higher rates, though not significant, of treatment failure (46%, including 60% with distant metastases, versus 35%, nearly all locoregional) and mortality (100% of treatment failures versus 73%). There were no significant between‐group differences in 5‐year disease‐free, disease‐specific, and overall survival.

Conclusion:  In this study, patients younger than 30 years of age presented with advanced tumour stages and with a different failure pattern compared to the older age group. This may be attributable to age‐related biologic behaviour or delayed cancer diagnosis. Differences in disease free survival and overall survival could not be established.
A Comparison of the Stability of Beverage Cloud Emulsions Formulated with Different Gum Acacia‐ and Starch‐Based Emulsifiers
Authors: Reiner S.J. , Reineccius G.A. , Peppard T.L.
Published: June 2010

Abstract:  The performance of several hydrocolloids (3 gum acacias, 1 modified gum acacia, and 3 modified starches) in stabilizing beverage emulsions and corresponding model beverages was investigated employing different core materials, emulsifier usage levels, and storage temperatures. Concentrated emulsions were prepared using orange terpenes or Miglyol® 812 (comprising medium‐chain triglycerides, MCT) weighted 1:1 with ester gum, stored at 25 or 35 °C, and analyzed on days 0, 1, and 3. On day 3, model beverages were made from each emulsion, stored at both temperatures, and analyzed weekly for 4 wk. Stability of concentrated emulsions was assessed by measuring mean particle size and by visual observations of ringing; beverage stability was judged similarly and also by loss of turbidity. Particle size measurements showed concentrated emulsions containing gum acacia or modified gum acacia with either core material were stable over 3 d storage at both temperatures whereas those made with modified starches were not, destabilization being faster at 35 °C. Beverages based on orange terpenes, in contrast to Miglyol, yielded smaller mean particle sizes, both on manufacture and during storage, regardless of hydrocolloid used. Visual observations of ringing generally supported this finding. Modified gum acacia was evaluated at both recommended and higher usage levels, stability increasing in the latter case. In general, all gum acacia and modified gum acacia emulsifiers were superior in stability to those based on modified starches, at either temperature, for orange terpene‐based beverages. In Miglyol‐based beverages, similar results were seen, except 1 modified starch performed as well as the gum acacia products.
Ultrasound of the posterior circumflex humeral artery
Authors: Robinson DJ , Marks P , Schneider‐Kolsky ME
Published: June 2010

Quadrilateral space syndrome (QSS) is described as compression neuropathy of the axillary neurovascular bundle in the quadrilateral space of the shoulder. This neurovascular bundle includes the posterior circumflex humeral artery (PCHA). Historically, angiography and more recently magnetic resonance angiography have been used to assess occlusion and stenosis of the PCHA in cases of suspected QSS. These traditional imaging techniques have a number of disadvantages in terms of cost, availability, invasiveness and patient comfort. We undertook to examine the ability of ultrasound to reliably visualise the PCHA. Asymptomatic adult volunteers were recruited from staff, and patients attending the radiology department who presented for pathologies unrelated to the shoulder. We used a new technique to assess blood flow in the PCHA, performing the scan from a posterolateral approach on the upper arm just above the level of the surgical neck of the humerus. This technique enabled the scan to be undertaken with the patient seated comfortably. Fifty volunteers were recruited into the study. The mean (±SD) age was 35 (±14 years). The PCHA was visualised in all patients. Our method was able to maximise Doppler sensitivity and visualisation of the artery without discomfort to the patient in less than 10 min. Ultrasound can be used to reliably visualise the PCHA. Ultrasound has potential to be used in the assessment of the PCHA in cases of QSS.
Clinical care and technical recommendations for 90yttrium microsphere treatment of liver cancer
Authors: Wang S‐C , Bester L , Burnes JP , Clouston JE , Hugh TJ , Little AF , Padbury RTA , Price D
Published: June 2010

Selective internal radiation therapy (SIRT) with 90yttrium microspheres is a relatively new clinical modality for treating non‐resectable malignant liver tumours. This interventional radiology technique employs percutaneous microcatheterisation of the hepatic arterial vasculature to selectively deliver radioembolic microspheres into neoplastic tissue. SIRT results in measurable tumour responses or delayed disease progression in the majority of eligible patients with hepatocellular carcinoma or hepatic metastases arising from colorectal cancer. It has also been successfully used as palliative therapy for non‐colorectal malignancies metastatic to the liver. Although most adverse events are mild and transient, SIRT also carries some risks for serious and – rarely – fatal outcomes. In particular, entry of microspheres into non‐target vessels may result in radiation‐induced tissue damage, such as severe gastric ulceration or radiation cholecystitis. Radiation‐induced liver disease poses another significant risk. By careful case selection, considered dose calculation and meticulous angiographic technique, it is possible to minimise the incidence of such complications to less than 10% of all treatments. As the number of physicians employing SIRT expands, there is an increasing need to consolidate clinical experience and expertise to optimise patient outcomes. Authored by a panel of clinicians experienced in treating liver tumours via SIRT, this paper collates experience in vessel mapping, embolisation, dosimetry, microsphere delivery and minimisation of non‐target delivery. In addition to these clinical recommendations, the authors propose institutional criteria for introducing SIRT at new centres and for incorporating the technique into multidisciplinary care plans for patients with hepatic neoplasms.
Randomised, placebo‐controlled, crossover trial of sildenafil citrate in the treatment of erectile dysfunction following external beam radiation treatment of prostate cancer
Authors: Harrington C , Campbell G , Wynne C , Atkinson C
Published: June 2010

Erectile dysfunction (ED) commonly affects the quality of life of men after treatment of prostate cancer. We conducted a placebo‐controlled, crossover randomised trial to assess the efficacy and tolerability of sildenafil citrate in the treatment of ED developing after external beam radiation treatment (EBRT) of localized prostate cancer. Sixty‐six patients who had developed ED following radiation treatment agreed to participate and were allocated to sildenafil or placebo to be taken prior to four sexual attempts. In the crossover period, subjects received the alternative tablet for a further four attempts. Allocation was centrally randomized, and researchers and patients were both blinded to the trial arm. Efficacy was assessed using the International Index of Erectile Function (IIEF) questionnaire and with a separate global efficacy question. Forty‐three subjects completed the study. There was a significant increase in mean scores from baseline for all domains of the IIEF with sildenafil compared with placebo (P < 0.001). Affirmative response to the global efficacy question was more common after taking sildenafil compared with placebo. In approximately half of the patients, the improvement in the erectile function domain score corresponded to a moderate improvement in ED (e.g. success ‘sometimes’ to ‘most times’). Sildenafil was associated with mild flushing, nasal stuffiness or indigestion in 8–10% patients and moderate flushing in 10%. The current study adds to the evidence that phosphodiesterase inhibitors are an effective and well‐tolerated treatment for ED after EBRT for prostate cancer.
Improving bladder cancer treatment with radiotherapy using separate intensity modulated radiotherapy plans for boost and elective fields
Authors: Van Rooijen DC , Van De Kamer JB , Hulshof MCCM , Koning CCE , Bel A
Published: June 2010

The aim of this study is to investigate to what extent IMRT can decrease the dose to the organs at risk in bladder cancer treatment compared with conformal treatment while making separate treatment plans for the elective field and the boost. Special attention is paid to sparing small intestines. Twenty patients who were treated with the field‐in‐field technique (FiF) were re‐planned with intensity modulated radiotherapy (IMRT) using five and seven beams, respectively. Separate treatment plans were made for the elective field (including the pelvic lymph nodes) and the boost, which enables position correction for bone and tumour separately. The prescribed dose was 40 Gy to the elective field and 55 or 60 Gy to the planning target volume (PTV). For bladder and rectum, V45Gy and V55Gy were compared, and for small intestines, V25Gy and V40Gy. The dose distribution with IMRT conformed better to the shape of the target. There was no significant difference between the techniques in dose to the healthy bladder. The median V40Gy of the small intestines decreased from 114 to 66 cc (P = 0.001) with five beam IMRT, and to 55 cc (P = 0.001) with seven beam IMRT compared with FiF. V45Gy for rectum decreased from 34.2% to 17.5% (P = 0.004) for both five and seven beam plans, while V55Gy for rectum remained the same. With IMRT, a statistically significant dose decrease to the small intestines can be achieved while covering both tumour and elective PTV adequately.
Effect of lateral target motion on image registration accuracy in CT‐guided helical tomotherapy: A phantom study
Authors: Medwig J , Gaede S , Battista JJ , Yartsev S
Published: June 2010

Optimisation of imaging modes for kilovoltage CT (kVCT) used for treatment planning and megavoltage CT (MVCT) image guidance used in ungated helical tomotherapy was investigated for laterally moving targets. Computed tomography images of the QUASAR™ Respiratory Motion Phantom were acquired without target motion and for lateral motion of the target, with 2‐cm peak‐to‐peak amplitude and a period of 4 s. Reference kVCT images were obtained using a 16‐slice CT scanner in standard fast helical CT mode, untagged average CT mode and various post‐processed 4D‐CT modes (0% phase, average and maximum intensity projection). Three sets of MVCT images with different inter‐slice spacings of were obtained on a Hi‐Art tomotherapy system with the phantom displaced by a known offset position. Eight radiation therapists performed co‐registration of MVCT obtained with 2‐, 4‐ and 6‐mm slice spacing and kVCT studies independently for all 15 CT imaging combinations. In the investigated case, the untagged average kVCT and 4‐mm slice spacing for the MVCT yielded more accurate registration in the transverse plane. The average residual uncertainty of this combination of imaging procedures was 0.61 ± 0.16 mm in the longitudinal direction, 0.45 ± 0.14 mm in the anterior–posterior direction and insignificant in the lateral direction. Manual registration of MVCT–kVCT study pairs is necessary to account for a target in significant lateral motion with respect to bony structures.
An indirect method for the characterization of locally reacting liners
Authors: Taktak Mohamed , Ville Jean Michel , Haddar Mohamed , Gabard Gwénaël , Foucart Felix
Published: June 2010

An indirect technique for educing the homogenized acoustic impedance of a liner mounted on the wall of a barrel is presented. It is based on measurements and computational simulations of the multimodal scattering matrix of this lined duct. Measurements are performed with a multisource method and the use of an anechoic duct termination. The numerical computation of the scattering matrix relies on a finite element model, and assume that the duct is axisymmetric and uniformly covered by a locally reacting material. The impedance is educed by minimizing the difference between the theoretical and experimental acoustic power dissipations, which are deduced from the scattering matrix. The source is an incoming pressure field generated at one end of the duct only and composed of all cut-on modes. This technique was tested on a cylindrical barrel whose wall was partially lined with a realistic, locally reacting material made of honeycomb cells and a perforated facing sheet. Results for the acoustic impedance are compared with those deduced from semiempirical models and the experimental two microphone method. The best agreement with the indirect method is found with the semiempirical impedance results when the difference between the acoustic power dissipated by the actual lined barrel and the reference barrel is chosen as the cost function of the minimizing procedure.
Analysis and classification of broadband echoes using bio-inspired dolphin pulses
Authors: Pailhas Yan , Capus Chris , Brown Keith , Moore Patrick
Published: June 2010

To date most sonars use narrow band pulses and often only the echo envelope is used for object detection and classification. This paper considers the advantages afforded by bio-inspired sonar for object identification and classification through the analysis and the understanding of the broadband echo structure. Using the biomimetic dolphin based sonar system in conjunction with bio-inspired pulses developed from observations of bottlenose dolphins performing object identification tasks, results are presented from experiments carried out in a wave tank and harbor. In these experiments responses of various targets to two different bio-inspired signals are measured and analyzed. The differences in response demonstrate the strong dependency between signal design and echo interpretation. In the simulations and empirical data, the resonance phenomena of these targets cause strong notches and peaks in the echo spectra. With precision in the localization of these peaks and dips of around 1 kHz, the locations are very stable for broadside insonification of the targets and they can be used as features for classification. This leads to the proposal of a broadband classifier which operates by extracting the notch positions in the target echo spectra.
Determination of postexcitation thresholds for single ultrasound contrast agent microbubbles using double passive cavitation detection
Authors: King Daniel A. , Malloy Michael J. , Roberts Alayna C. , Haak Alexander , Yoder Christian C. , O’Brien William D.
Published: June 2010

This work presents experimental responses of single ultrasound contrast agents to short, large amplitude pulses, characterized using double passive cavitation detection. In this technique, two matched, focused receive transducers were aligned orthogonally to capture the acoustic response of a microbubble from within the overlapping confocal region. The microbubbles were categorized according to a classification scheme based on the presence or absence of postexcitation signals, which are secondary broadband spikes following the principle oscillatory response of the ultrasound contrast agent and are indicative of the transient collapse of the microbubble. Experiments were conducted varying insonifying frequencies (0.9, 2.8, 4.6, and 7.1 MHz) and peak rarefactional pressures (200 kPa to 6.2 MPa) for two types of contrast agents (Definity® and Optison™). Results were fit using logistic regression analysis to define pressure thresholds where at least 5% and 50% of the microbubble populations collapsed for each frequency. These thresholds were found to occur at lower pressures for Definity than for Optison over the range of frequencies studied; additionally, the thresholds occurred at lower pressures with lower frequencies for both microbubble types in most cases, though this trend did not follow a mechanical index scaling.
Modeling the use of durational information in human spoken-word recognition
Authors: Scharenborg Odette
Published: June 2010

Evidence that listeners, at least in a laboratory environment, use durational cues to help resolve temporarily ambiguous speech input has accumulated over the past decades. This paper introduces Fine-Tracker, a computational model of word recognition specifically designed for “tracking” fine-phonetic information in the acoustic speech signal and using it during word recognition. Two simulations were carried out using real speech as input to the model. The simulations showed that the Fine-Tracker, as has been found for humans, benefits from durational information during word recognition, and uses it to disambiguate the incoming speech signal. The availability of durational information allows the computational model to distinguish embedded words from their matrix words (first simulation), and to distinguish word final realizations of [s] from word initial realizations (second simulation). Fine-Tracker thus provides the first computational model of human word recognition that is able to extract durational information from the speech signal and to use it to differentiate words.
Location and acoustic scale cues in concurrent speech recognition
Authors: Ives D. Timothy , Vestergaard Martin D. , Kistler Doris J. , Patterson Roy D.
Published: June 2010

Location and acoustic scale cues have both been shown to have an effect on the recognition of speech in multi-speaker environments. This study examines the interaction of these variables. Subjects were presented with concurrent triplets of syllables from a target voice and a distracting voice, and asked to recognize a specific target syllable. The task was made more or less difficult by changing (a) the location of the distracting speaker, (b) the scale difference between the two speakers, and/or (c) the relative level of the two speakers. Scale differences were produced by changing the vocal tract length and glottal pulse rate during syllable synthesis: 32 acoustic scale differences were used. Location cues were produced by convolving head-related transfer functions with the stimulus. The angle between the target speaker and the distracter was 0°, 4°, 8°, 16°, or 32° on the 0° horizontal plane. The relative level of the target to the distracter was 0 or −6 dB. The results show that location and scale difference interact, and the interaction is greatest when one of these cues is small. Increasing either the acoustic scale or the angle between target and distracter speakers quickly elevates performance to ceiling levels.
Correspondence between behavioral and individually “optimized” otoacoustic emission estimates of human cochlear input/output curves
Authors: Johannesen Peter T. , Lopez-Poveda Enrique A.
Published: June 2010

Previous studies have shown a high within-subject correspondence between distortion product otoacoustic emission (DPOAE) input/output (I/O) curves and behaviorally inferred basilar membrane (BM) I/O curves for frequencies above ∼2 kHz. For lower frequencies, DPOAE I/O curves contained notches and plateaus that did not have a counterpart in corresponding behavioral curves. It was hypothesized that this might improve by using individualized optimal DPOAE primary levels. Here, data from previous studies are re-analyzed to test this hypothesis by comparing behaviorally inferred BM I/O curves and DPOAE I/O curves measured with well-established group-average primary levels and two individualized primary level rules: one optimized to maximize DPOAE levels and one intended for primaries to evoke comparable BM responses at the f2 cochlear region. Test frequencies were 0.5, 1, and 4 kHz. Behavioral I/O curves were obtained from temporal (forward) masking curves. Results showed high within-subject correspondence between behavioral and DPOAE I/O curves at 4 kHz only, regardless of the primary level rule. Plateaus and notches were equally common in low-frequency DPOAE I/O curves for individualized and group-average DPOAE primary levels at 0.5 and 1 kHz. Results are discussed in terms of the adequacy of DPOAE I/O curves for inferring individual cochlear nonlinearity characteristics.
Inversion for range-dependent water column sound speed profiles on the New Jersey shelf using a linearized perturbative method
Authors: Ballard Megan S. , Becker Kyle M.
Published: June 2010

The environment of the New Jersey shelf is characterized by high spatial and temporal variability of water column properties caused by intrusions of warm, salty water from the continental slope. These intrusions cause fluctuations in the water column sound speed profile which can have significant effects on acoustic propagation in shallow water. In this work, a linearized perturbative inverse technique is applied to estimate range-dependent water column sound speed profiles. This method utilizes estimates of horizontal wave numbers to determine sound speed as a function of depth. This technique is appropriate for the range-dependent shallow-water environment as horizontal wave numbers can be measured semilocally (1–2 km aperture) and their values are a direct measurement of the local environmental parameters. Difficulty is encountered in application of the perturbative inverse technique because the wave number data are insensitive to some portions of the waveguide and, as a result, the solution can deviate wildly from true values. This issue is addressed by application of approximate equality constraints which force the solution to be close to likely values at prescribed locations.
Theory of compact nonporous windscreens for infrasonic measurements
Authors: Zuckerwar Allan J.
Published: June 2010

The principle of the compact nonporous windscreen is based on the great penetrability of infrasound through matter. The windscreen performance is characterized by the ratio of the sound pressure at an interior microphone, located in the center of a windscreen, to the incident sound pressure in the free field. The frequency dependence of this pressure ratio is derived as a function of the windscreen material and geometric properties. Four different windscreen geometries are considered: a subsurface, box-shaped windscreen, a cylindrical windscreen of infinite length, a cylindrical windscreen of finite length, and a spherical windscreen. Results are presented for windscreens made of closed-cell polyurethane foam and for typical dimensions of each of the above geometries. The cylindrical windscreen of finite length, featuring evanescent radial modes, behaves as a unity-gain, low-pass filter, cutting off sharply at the end of the infrasonic range. The remaining geometries reveal a pass band that extends well into the audio range, terminated by a pronounced peak beyond which the response plummets rapidly.
Paleomagnetism of the Methow region, north-central Washington: structural application of paleomagnetic data in a complexly deformed, variably remagnetized terrane
Authors: Bazard David R. , Burmester Russell F. , Beck Jr. Myrl E. , Granirer Julian L. , Schwarz Charles G.
Published: June 2010

Jurassic through Paleocene rocks of the Methow–Pasayten belt were studied in order to use paleomagnetic directions to resolve the question of Cretaceous northward transport. In the end, circumstances prevented us from doing so. However, three independent studies of these rocks, summarized here, indicate that several units retain strong and stable magnetizations that are different from the present axial dipole field direction. When partly or completely corrected to paleohorizontal, these magnetizations become less dispersed, suggesting that they were acquired before at least the last stage of Late Cretaceous deformation. A pervasive northeast–southwest streak of magnetizations at various stages of structural correction indicates that at least some of the rocks were partly to completely remagnetized at different times during folding. This complex structural–remagnetization history and consequent loss of paleohorizontal prevent a simple analysis of paleolatitude during remagnetization. However, analysis of the youngest layered rocks of the Goat Peak syncline indicates that much of the remagnetization occurred when the structure was more open but still well developed. Subsequent tighter folding followed intrusion of the Fawn Peak stock. Our results are a useful case study of some of the problems that arise in studying the paleomagnetism of a complicated orogenic terrane.
The Anvil aureole, an atypical mid-Cretaceous culmination in the northern Canadian Cordillera
Authors: Smith J. M. , Erdmer P.
Published: June 2010

The mid-Cretaceous Anvil batholith, in south-central Yukon near Faro, intrudes Upper Proterozoic to upper Paleozoic strata of the Cordilleran outer miogeocline. From previous work, it was unclear whether biotite, andalusite–staurolite, and garnet isograds near the pluton resulted from pre-Devonian regional metamorphism and subsequent arching in a structural culmination or from mid-Cretaceous instrusion. The present study has documented biotite, andalusite, staurolite, garnet, and sillimanite isograds concentric to the pluton. Prophyroblast–matrix relationships indicate that peak metamorphism occurred during intrusion, which took place under approximately 3 kbar (300 MPa) pressure and heated country rock to temperatures of 600°–620 °C. The metamorphism is thus compatible with a deep, mid-Cretaceous event. Regional uplift of 10 km is implied by the metamorphic minerals. From cogenetic relationships between some phases of the Anvil batholith and the nearby South Fork volcanic rocks, regional uplift appears to have been completed in a few million years in the mid-Cretaceous. The uncharacteristic aureole suggests that mid-Cretaceous events in this region are atypical of the Cordillera and may reflect a unique tectonic history or position in the orogen.
Metamorphic constraints on the tectonic evolution of the allochthonous monocyclic belt of the Grenville Province, western Quebec
Authors: Indares A. , Martignole J.
Published: June 2010

The tectono-metamorphic evolution of Grenvillian monocyclic terranes in western Quebec has been constrained along a northwest–southeast transect from Réservoir Cabonga to the Morin anorthosite by the study of garnet zoning and the application of geothermobarometric techniques to appropriate mineral assemblages. In all three terrenes examined (Réservoir Cabonga, Mont-Laurier, and Morin terranes), the results are consistent with Grenvillian metamorphism induced by thrusting. Additional magmatic heat may have been provided by the cooling of igneous rocks related to the Morin anorthosite complex.After the peak of the Grenvillian metamorphism, the monocyclic rocks were sliced, and three Grenvillian crustal levels, sharing some of their lithologic elements but having contrasting Grenvillian peak-metamorphic conditions, were subsequently juxtaposed. The deepest crustal level exposed in the transect (level A) comprises the Réservoir Cabonga terrene and the margins of the Mont-Laurier terrene. This level consists of metasediments of the "Grenville Supergroup," garnet amphibolites, and synmetamorphic plutonites whose emplacement predated the thrusting. Metamorphic conditions in level A are estimated at 725–875 MPa and 725–800 °C. Level C, which is exclusively in the central part of the Mont-Laurier terrene, comprises metasediments of the Grenville Supergroup that were metamorphosed at 425–600 MPa and 625–725 °C. Synmetamorphic igneous rocks of the Morin plutonic complex in the Morin terrane were metamorphosed at 600–800 MPa and 650–775 °C, probably in an intermediate crustal level B, which is missing in the Mont-Laurier terrane. It is thus suggested that juxtaposition of the Mont-Laurier terrane and the Morin terrane along the Labelle shear belt occurred after the peak of metamorphism.A comparison of the metamorphic evolution of these monocyclic terranes with that of their adjacent polycyclic counterparts suggests that (i) the Réservoir Cabonga terrane was thrust over the parautochthonous Réservoir Dozois terrane after the peak of metamorphism and (ii) level A rocks of the Mont-Laurier terrane and the Réservoir Baskatong terrane were juxtaposed during the peak of metamorphism.
Cycles of sand-flat sandstone and playa–lacustrine mudstone in theTriassic–Jurassic Blomidon redbeds, Fundy rift basin, Nova Scotia: implications for tectonic and climatic controls
Authors: Mertz Jr. Karl A. , Hubert John F.
Published: June 2010

The redbeds of the 220 m Blomidon Formation comprise more than 100 pairs of (i) sand-flat sandstone (distal alluvial fan) and (ii) playa sandy mudstone and (or) lacustrine claystone. These pairs are tectonic autocycles generated by rift-basin subsidence and sagging along the Glooscap fault zone that shifted loci of active fan sedimentation toward and away from the playa surface as fan lobes migrated into topographically low areas.Intervals of intense and prolonged aridity are recorded in many of the sand-flat sandstones and playa sandy mudstones by evaporite minerals, principally gypsum, precipitated by subsurface evolution of a CaSO4–NaCl brine. Aridity is further demonstrated by intense disruption of sediment fabrics beneath evaporite crusts, deep mudcracks, eolian-sandstone layers and patches, and the presence of authigenic Ca–Mg-rich illite–smectite and analcime. During relatively wetter intervals, claystone beds accumulated in shallow lakes that filled the playa depression, lapping onto the sand flats. The claystones lack evaporite minerals and textures, and many are partially bioturbated.The long-term climate became progressively wetter from latest Triassic to earliest Jurassic time, as evidenced by an increase upsection in the ratio of lacustrine claystone to playa sandy mudstone and by less evaporite mineralization in the sand-flat sandstones.