bluuebunny/crossref_metadata_2025 huggingface dataset:
A review of topically administered mini-tablets for drug delivery to the anterior segment of the eye
Authors: Moosa Raeesa M , Choonara Yahya E , du Toit Lisa C , Kumar Pradeep , Carmichael Trevor , Tomar Lomas Kumar , Tyagi Charu , Pillay Viness
Published: August 2013

Objectives

The human eye is a unique and intricate structure which has made drug delivery to the eye a formidable undertaking. Anterior-segment eye diseases are ubiquitous, especially among elderly patients, and conventional eye drops, although a first-choice dosage form, are not always an efficient treatment option. The development of novel drug delivery systems for improved treatment is therefore imperative.

Key findings

In an attempt to circumvent the obstacles presented by the structure of the eye, advanced systems such as ocular mini-tablets have been developed. In this review, a concerted effort has been made to provide a detailed overview of topically administered ocular mini-tablets and other solid devices for drug delivery to the anterior segment of the eye. These mini-tablets have been shown in vitro and in vivo to have significant advantages in comparison with liquid preparations. This is a step toward attaining better patient convenience and compliance, which are critical factors.

Solid ophthalmic dosage forms have several advantages that can contribute to assisting with patient compliance and, ultimately, effective disease treatment. In addition to the challenges associated with topical ocular drug delivery, the shortcomings of conventional eye drops, advantages of mini-tablets, and improvements to date to these systems are discussed. The requirement for further advancements in the ocular field is also emphasized.
Risk factors for hepatocellular carcinoma in hepatitis C patients with normal alanine aminotransferase treated with pegylated interferon and ribavirin
Authors: Harada N. , Hiramatsu N. , Oze T. , Morishita N. , Yamada R. , Hikita H. , Miyazaki M. , Yakushijin T. , Miyagi T. , Yoshida Y. , Tatsumi T. , Kanto T. , Kasahara A. , Oshita M. , Mita E. , Hagiwara H. , Inui Y. , Katayama K. , Tamura S. , Yoshihara H. , Imai Y. , Inoue A. , Hayashi N. , Takehara T.
Published: August 2013

Pegylated interferon (Peg‐IFN) plus ribavirin combination therapy is effective in patients with hepatitis C virus (HCV) infection and normal alanine aminotransferase levels (NALT). However, it remains unclear whether the risk of hepatocellular carcinoma (HCC) incidence is actually reduced in virological responders. In this study, HCC incidence was examined for 809 patients with NALT (ALT ≤ 40 IU/mL) treated with Peg‐IFN alpha‐2b and ribavirin for a mean observation period of 36.2 ± 16.5 months. The risk factors for HCC incidence were analysed by Kaplan–Meier method and Cox proportional hazards model. On multivariate analysis among NALT patients, the risk of HCC incidence was significantly reduced in patients with sustained virological response (SVR) or relapse compared with those showing nonresponse (NR) (SVR vs NR, hazard ratio (HR): 0.16, P = 0.009, relapse vs NR, HR: 0.11, P = 0.037). Other risk factors were older age (≥65 years vs <60 years, HR: 6.0, P = 0.032, 60–64 vs <60 years, HR: 3.2, P = 0.212) and male gender (HR: 3.9, P = 0.031). Among 176 patients with PNALT (ALT ≤ 30 IU/mL), only one patient developed HCC and no significant risk factors associated with HCC development were found. In conclusion, antiviral therapy for NALT patients with HCV infection can lower the HCC incidence in responders, particularly for aged and male patients. The indication of antiviral therapy for PNALT (ALT ≤ 30 IU/mL) patients should be carefully determined.
Enhanced high‐mobility group box 1 (HMGB1) modulates regulatory T cells (Treg)/T helper 17 (Th17) balance via toll‐like receptor (TLR)‐4‐interleukin (IL)‐6 pathway in patients with chronic hepatitis B
Authors: Li J. , Wang F.‐P. , She W.‐M. , Yang C.‐Q. , Li L. , Tu C.‐T. , Wang J.‐Y. , Jiang W.
Published: August 2013

High‐mobility group box 1 (HMGB1) proteins are substantially up‐regulated in acute and chronic hepatitis. However, the immunopathogenic role of HMGB1 in patients with chronic hepatitis B (CHB) has not been elucidated. In this study, using a cohort of 36 CHB patients, we demonstrated a crucial role for HMGB1 to modulate balance between regulatory T (Treg) and T helper 17 (Th17) cells via the toll‐like receptor (TLR)‐4‐interleukin (IL)‐6 pathway. Serum HMGB1 levels were dramatically higher in CHB patients and increased along with liver injury, inflammation and fibrosis. Notably, HMGB1 increased along with decreased Treg/Th17 cells ratios in the periphery or intrahepatic microenvironment, which provides a clue for HMGB1 to favour Th17 responses whereas inhibit Treg responses. For in vitro studies, serum pools were constructed with serum from CHB patients at an advanced stage, whereas peripheral blood mononuclear cells (PBMC) pools were constructed with cells from those at an early stage. CHB‐serum significantly enhanced retinoic acid‐related orphan receptor‐γt (RORγt), whereas they inhibited forkhead box P3 (Foxp3) expression in CHB‐PBMC, which could be reversed by blocking of HMGB1, TLR4, or IL‐6. Besides, recombinant HMGB1 (rHMGB1) dose‐dependently up‐regulated RORγt whereas down‐regulated Foxp3 expression in CHB‐PBMC, and meanwhile, rHMGB1 enhanced TLR4 and IL‐6 expression in CHB‐PBMC. Moreover, the axis of HMGB1–TLR4‐IL‐6–Treg/Th17 required noncontact interactions between CD4 and non‐CD4 cells. In addition, rHMGB1 down‐regulated anti‐inflammatory proteins on CD4+CD25+ cells whereas up‐regulated pro‐inflammatory cytokines in CD4+CD25− cells. In summary, enriched HMGB1 in CHB patients shifts Treg/Th17 balance to Th17 dominance via the TLR4‐IL‐6 pathway, which exacerbates liver injury and inflammation.
Hypercoagulability andACTH‐Dependent Hyperadrenocorticism in Dogs
Authors: Park F.M. , Blois S.L. , Abrams‐Ogg A.C.G. , Wood R.D. , Allen D.G. , Nykamp S.G. , Downie A.
Published: August 2013

Background

Dogs with hyperadrenocorticism are at risk of thromboembolic disease, which might be caused by an underlying hypercoagulable state.

Hypothesis/Objectives

To assess hemostatic function in dogs withACTH‐dependent hyperadrenocorticism (ADHAC) before and after treatment.

Animals

Nineteen dogs withADHACand 40 normal dogs.

Methods

Prospective, observational study. Dogs with ADHAC were recruited from the referral hospital patient population; normal dogs were recruited from staff and students at the study's institution. Hemostasis was assessed before and at 3 and 6 months after treatment with trilostane (T0, T3, T6) by kaolin‐activated thrombelastography with platelet mapping (TEG‐PM), prothrombin time, activated partial thromboplastin time, fibrinogen concentration, and antithrombin activity (AT).

Results

Dogs withADHAChad statistically significantly increased α‐angle (P < .01) and maximum amplitude (MA)thrombin(P < .01) onTEG‐PM, and significantly decreased κ (P < .005) at T0, T3, and T6. Platelet count (P < .001) and fibrinogen concentration (P < .001), but notATactivity, were increased in dogs withADHACat T0, T3, and T6.

Conclusions and Clinical Importance

Dogs withADHAChave thrombelastographic evidence of hypercoagulability and remained hypercoagulable during treatment.ATdeficiency does not appear to be involved in the pathogenesis of hypercoagulability in this population.
Migraine‐like Episodic Pain Behavior in a Dog: Can Dogs Suffer from Migraines?
Authors: Plessas I.N. , Volk H.A. , Kenny P.J.
Published: August 2013

Migraines and other primary headache disorders commonly affect people. There is evidence to suggest that migraines can occur in dogs. In this review, we present a dog with paroxysmal episodes that have a striking resemblance to human migraine, and we give an overview of migraine in people. The current classification, clinical signs, and diagnosis in people are discussed, as well as the anatomy of head pain, pathophysiology, pharmacology, and treatment options.
Pharmacokinetic/pharmacodynamic relationship of marbofloxacin against Pasteurella multocida in a tissue‐cage model in yellow cattle
Authors: Shan Q. , Wang J. , Yang F. , Ding H. , Liang C. , Lv Z. , Li Z. , Zeng Z.
Published: August 2013

The fluoroquinolone antimicrobial drug marbofloxacin was administered to yellow cattle intravenously and intramuscularly at a dose of 2 mg/kg of body weight in a two‐period crossover study. The pharmacokinetic properties of marbofloxacin in serum, inflamed tissue‐cage fluid (exudate), and noninflamed tissue‐cage fluid (transudate) were studied by using a tissue‐cage model. The in vitro and ex vivo activities of marbofloxacin in serum, exudate, and transudate against a pathogenic strain of Pasteurella multocida (P. multocida) were determined. Integration of in vivo pharmacokinetic data with the in vitro MIC provided mean values for the area under the curve (AUC)/MIC for serum, exudate, and transudate of 155.75, 153.00, and 138.88, respectively, after intravenous dosing and 160.50, 151.00, and 137.63, respectively, after intramuscular dosing. After intramuscular dosing, the maximum concentration/MIC ratios for serum, exudate, and transudate were 21.13, 9.13, and 8.38, respectively. The ex vivo growth inhibition data after intramuscular dosing were fitted to the inhibitory sigmoid Emax equation to provide the values of AUC/MIC required to produce bacteriostasis, bactericidal activity, and elimination of bacteria. The respective values for serum were 17.25, 31.29, and 109.62, and slightly lower values were obtained for transudate and exudate. It is proposed that these findings might be used with MIC50 or MIC90 data to provide a rational approach to the design of dosage schedules which optimize efficacy in respect of bacteriological as well as clinical cures.
Applications and functions of food‐grade phosphates
Authors: Lampila Lucina E.
Published: August 2013

Food‐grade phosphates are used in the production of foods to function as buffers, sequestrants, acidulants, bases, flavors, cryoprotectants, gel accelerants, dispersants, nutrients, precipitants, and as free‐flow (anticaking) or ion‐exchange agents. The actions of phosphates affect the chemical leavening of cakes, cookies, pancakes, muffins, and doughnuts; the even melt of processed cheese; the structure of a frankfurter; the bind and hydration of delicatessen meats; the fluidity of evaporated milk; the distinctive flavor of cola beverages; the free flow of spice blends; the mineral content of isotonic beverages; and the light color of par‐fried potato strips. In the United States, food‐grade phosphates are generally recognized as safe, but use levels have been defined for some foods by the Code of Federal Regulations, specifically Titles 9 and 21 for foods regulated by the U.S. Department of Agriculture (USDA) and the U.S. Food and Drug Administration (FDA), respectively. Standards for food purity are defined nationally and internationally in sources such as the Food Chemicals Codex and the Joint Food and Agriculture Organization and World Health Organization (FAO/WHO) Expert Committee on Food Additives.
Three‐dimensional evaluation of upper airway in patients with different anteroposterior skeletal patterns
Authors: Zheng Z. H. , Yamaguchi T. , Kurihara A. , Li H. F. , Maki K.
Published: August 2013

Structured Abstract

Objectives

To investigate variability in the upper airway of subjects with different anteroposterior skeletal patterns by evaluating the volume and the most constricted cross‐sectional area of the pharyngeal airway and defining correlations between the different variables.

Material and methods

The study sample consisted of 60 patients (29 boys, 31 girls) divided into three groups: Class I (1 ≤ ANB≤3), Class II (ANB>3), and Class III (ANB<1), to evaluate how the jaw relationship affects the airway volume and the most constricted cross‐sectional area (Min‐CSA). Differences between groups were determined using the Tukey–Kramer test. Correlations between variables were tested using Pearson's correlation coefficient.

Results

The volume and the Min‐CSA of the pharyngeal airway (PA) were significantly related to anteroposterior skeletal patterns (p < 0.05). The nasopharyngeal airway (NA) volume of Class I and Class III subjects was significantly larger than that of Class II subjects (p < 0.05). The Min‐CSA and the length of PA were significantly related to the volume of PA (p < 0.05). The site and the size of the Min‐CSA varied among the three groups.

Conclusions

The volume and the most constricted cross‐sectional area of the airway varied with different anteroposterior skeletal patterns. The NA volume of Class I and Class III subjects was significantly larger than that of patients with a Class II skeletal pattern.
The association between bone mineral density and periodontitis in Korean adults (KNHANES 2008–2010)
Authors: Kim J‐W , Kong K‐A , Kim H‐Y , Lee H‐S , Kim S‐J , Lee S‐H , Sim K‐W , Kim M‐R , Lee J‐H
Published: August 2013

Objectives

This study investigated the association between bone mineral density (BMD) and periodontitis in a representative sample of Korean adults.

Material and Methods

Of 36 188 individuals who participated in the Korea National Health and Nutrition Examination Survey in 2008, 2009, and 2010, 9977 participants aged ≥40 years were included in this cross‐sectional study. The associations of BMD of lumbar spine, total femur, and femoral neck with periodontitis were investigated using logistic regression analysis. Additionally, dose–response relationships with BMD divided into quintiles and the association between osteoporosis and periodontitis were investigated.

Results

With the set of Community Periodontal Index (CPI) ≥ 3 as a dependent variable, logistic regression analysis revealed that a decrease of BMD was significantly associated with higher odds of periodontitis [range of adjusted odds ratios (AORs); 1.15–1.20, P < 0.001 for all BMD sites]. Similarly, these associations were also found in the CPI 4 model. With regard to dose–response relations, the lower the BMD quintile, the higher the AORs appeared with statistical significance in the CPI ≥ 3 model. (P for trend < 0.001) Participants with osteoporosis had 2.26 and 1.91 times higher odds for CPI ≥ 3 and CPI 4, respectively, than those with normal BMD, indicating a significant association between the two diseases.

Conclusions

Our results suggest that BMD is significantly associated with periodontitis.
Radiofrequency Catheter Ablation for the Treatment of Idiopathic Premature Ventricular Contractions Originating from the Right Ventricular Outflow Tract: A Systematic Review and Meta‐Analysis
Authors: LAMBA JASMINE , REDFEARN DAMIAN P. , MICHAEL KEVIN A. , SIMPSON CHRISTOPHER S. , ABDOLLAH HOSHIAR , BARANCHUK ADRIAN
Published: August 2013

Background

Frequent idiopathic premature ventricular contractions (PVCs) have been associated with left ventricular cardiomyopathy. Idiopathic PVCs often originate from the right ventricular outflow tract (RVOT), and radiofrequency catheter ablation (RFCA) is being used as a treatment to alleviate symptoms. A meta‐analysis was performed to evaluate RFCA for the treatment of frequent idiopathic PVCs on heart function.

Methods and Results

A literature search was conducted using Medline and Embase to identify studies evaluating the effects of RFCA as treatment for PVCs originating from the RVOT. Articles were chosen if they reported the effect of RFCA on the quantity of PVCs or ventricular function. Only studies in English were included. Articles were excluded if they did not separate results for PVCs originating from areas other than the RVOT. A total of 450 articles were retrieved from electronic searches, and 14 articles were included in this systematic review. Six of these were meta‐analyzed (N = 70) and showed a reduction in the total number of PVCs in 24 hours after RFCA by a mean of –30089.44 confidence interval [CI]: –31658.47, –28520.40, P < 0.00001). Left ventricular ejection fraction (LVEF) was reported in five of the 14 studies, which included 108 patients. RFCA significantly improved LVEF by a mean of 10.36 (CI: 8.75, 11.97, P < 0.00001) in patients with frequent PVCs from the RVOT. The remaining studies reported their results differently and were not included in the meta‐analyses but were described separately.

Conclusions

RFCA reduces the number of PVCs and improves the cardiac function in patients with idiopathic frequent PVCs originating from the RVOT.
Patient, Physician, and Procedural Factors Influencing the Use of Defibrillation Testing during Initial Implantable Cardioverter Defibrillator Insertion: Findings from the NCDR®
Authors: RUSSO ANDREA M. , WANG YONGFEI , AL‐KHATIB SANA M. , CURTIS JEPTHA P. , LAMPERT RACHEL
Published: August 2013

Background

Advances in implantable cardioverter defibrillator (ICD) technology have resulted in more effective defibrillation, and the need for defibrillation threshold (DFT) testing has been questioned.

Methods

A total of 64,227 initial ICD implant procedures performed at 1,261 facilities (April to December 2010) in the NCDR Registry™ were selected to identify patterns of practice related to DFT testing. Patient, physician, and procedural characteristics were compared. Independent association of DFT testing with in‐hospital adverse events or mortality was also examined.

Results

DFT testing was performed in 71% of patients. Patients who did not undergo testing were older; more often had heart failure, lower left ventricular ejection fraction, atrial arrhythmias, and a primary prevention indication; and were more likely to receive a cardiac resynchronization therapy device. In addition, patients who did not undergo testing were less likely to be implanted in a metropolitan area and more often implanted at a teaching hospital, in New England, in the Mid‐Atlantic, or in the Pacific U.S . In‐hospital adverse events occurred in 2.56% of patients who underwent DFT testing compared to 3.58% who did not (P < 0.001). Death or any complication remained more likely to occur in patients who did not undergo testing (odds ratio and 95% confidence interval: 1.46 [1.33, 1.61], P < 0.001), after adjusting for baseline and procedural differences.

Conclusions

DFT testing is not performed in many (29%) patients in clinical practice. Patients who did not undergo testing were more likely to have adverse events and to be older with more comorbidities, which could explain why DFT testing was avoided. Prospective randomized data are needed to determine the impact of DFT testing on outcome.
Hydrolase treatments help unravel the function of intervessel pits in xylem hydraulics
Authors: Dusotoit‐Coucaud Anaïs , Brunel Nicole , Tixier Aude , Cochard Hervé , Herbette Stéphane
Published: August 2013

Intervessel pits are structures that play a key role in the efficiency and safety functions of xylem hydraulics. However, little is known about the components of the pit membrane (PM) and their role in hydraulic functions, especially in resistance to cavitation. We tested the effect of commercial chemicals including a cellulase, a hemicellulase, a pectolyase, a proteinase and DTT on xylem hydraulic properties: vulnerability to cavitation (VC) and conductance. The effects were tested on branch segments from Fagus sylvatica (where the effects on pit structure were analyzed using TEM) and Populus tremula. Cellulose hydrolysis resulted in a sharp increase in VC and a significant increase in conductance, related to complete breakdown of the PM. Pectin hydrolysis also induced a sharp increase in VC but with no effect on conductance or pit structure observable by TEM. The other treatments with hemicellulase, proteinase or DTT showed no effect. This study brings evidence that cellulose and pectins are critical components underpinning VC, and that PM components may play distinct roles in the xylem hydraulic safety and efficiency.
Economic models as devices of policy change: Policy paradigms, paradigm shift, and performativity
Authors: Henriksen Lasse F.
Published: August 2013

Can the emergence of a new policy model be a catalyst for a paradigm shift in the overall interpretative framework of how economic policy is conducted within a society? This paper claims that models are understudied as devices used by actors to induce policy change. This paper explores the role of models in Danish economic policy, where, from the 1970s onwards, executive public servants in this area have exclusively been specialists in model design. To understand changes in economic policy, this paper starts with a discussion of whether the notion of paradigm shift is adequate. It then examines the extent to which the performativity approach can help identify macroscopic changes in policy from seemingly microscopic changes in policy models. The concept of performativity is explored as a means of thinking about the constitution of agency directed at policy change. The paper brings this concept into play by arguing that the “performative” embedding of models in institutions is an important aspect of how paradigm shifts unfold that the current literature has neglected.
Confronting trade‐offs and interactive effects in the choice of policy focus: Specialized versus comprehensive private governance
Authors: Auld Graeme
Published: August 2013

In setting standards for responsible business practices, certification programs create issue boundaries delineated by the focus of their standards. These issue boundaries may impede action on certain causes of problems (i.e. problem interactive effects) or lead to policy actions that affect other governance initiatives (i.e. policy interactive effects). When these interactions are extensive, programs confront trade‐offs: develop as a comprehensive program (i.e. have a broad policy focus) and take on higher internal administrative costs, or develop as a specialized program (i.e. have a narrow policy focus) and undertake to develop mechanisms to facilitate across‐program coordination. This paper explores these trade‐offs. It examines the origins of the different policy foci of coffee, forest, and fisheries certification programs, and identifies five strategies that programs are currently using to manage policy and/or problem interactive effects. Then, informed by research in public administration and international relations, it details additional approaches for improving issue‐boundary management.
Vinorelbine rescue therapy for dogs with primary urinary bladder carcinoma
Authors: Kaye M. E. , Thamm D. H. , Weishaar K. , Lawrence J. A.
Published: August 2013

The goal of this study was to evaluate the anti‐tumour activity and toxicoses of vinorelbine as a palliative rescue therapy for dogs with primary urinary bladder carcinoma. Thirteen dogs refractory to prior chemotherapeutics and one dog naïve to chemotherapeutic treatment were enrolled. Vinorelbine (15 mg m−2IV) was administered intravenously along with concurrent oral anti‐inflammatory drugs, if tolerated. A median of six doses of vinorelbine (range: 1–16) was administered. Two dogs (14%) had partial responses, and eight (57%) experienced stable disease. Subjective improvement in clinical signs was noted in 11 dogs (78%). Adverse events were mild and primarily haematological in nature. Median time to progression was 93 days (range: 20–239 days). Median survival time for all dogs was 187 days; median survival for 13 pre‐treated dogs was 207 days. Vinorelbine may have utility in the management of canine primary urinary bladder carcinoma and should be evaluated in a prospective study.
Impact of site conditions and farming practices on the occurrence of rare and endangered weeds on arable land in the Czech Republic
Authors: Kolářová M , Tyšer L , Soukup J
Published: August 2013

This article documents the impact of site conditions and farming practices on the occurrence of rare and endangered weeds on arable land in the Czech Republic. A survey was conducted between 2006 and 2008 in winter cereals, spring cereals and wide‐row crops. The relationship between the occurrence of plants and explanatory factors was analysed using a multivariate analysis to calculate species frequencies in different types of farming, crops and altitudes. In total, 290 relevés were recorded, with a total number of 172 weed species. Nineteen weeds, classified as rare and endangered species according to the national Czech list, were identified in 106 relevés. The highest effect on the occurrence of rare and endangered weed species was observed for altitude. Almost half of the recorded endangered and rare species belonged to the thermophilous weed vegetation typical for cereals on basic soils. A higher occurrence of endangered species has been confirmed for organic farming, where the sum of frequencies was 4.5 times higher than in conventional farming. Field size was not included in our analyses, but could be a factor affecting weed assemblages. The highest frequency of rare species was recorded in spring cereals, followed by winter cereals and wide‐row crops. Higher numbers were identified within fields with higher weed coverage. Lower farming intensity and diversified farming systems at higher altitudes provided better conditions for the occurrence of rare species than intensively farmed lowlands.
Plastic Response Estimation in Repeated Elastic Analyses for Strain Hardening Material Model
Authors: Mahmood S. L. , Adibi-Asl R. , Daley C. G.
Published: August 2013

Simplified limit analysis techniques have already been employed for limit load estimation on the basis of linear elastic finite element analysis (FEA) assuming elastic-perfectly-plastic material model. Due to strain hardening, a component or a structure can store supplementary strain energy and hence carries additional load. In this paper, an iterative elastic modulus adjustment scheme is developed in context of strain hardening material model utilizing the “strain energy density” theory. The proposed algorithm is then programmed into repeated elastic FEA and results from the numerical examples are compared with inelastic FEA results.
Heliostat Field Layout Improvement by Nonrestricted Refinement
Authors: Buck Reiner
Published: August 2013

A new method for the heliostat field optimization is presented. The method is intended for further performance improvement after initial layout with a standard heliostat field layout tool. During the field refinement, the heliostats are repositioned around their original position, without or with little restrictions. A nonsimplifying ray-tracing tool is used for the performance evaluation. During the optimization, detailed local weather and site characteristics (e.g., topography) can be considered. An example case is presented and discussed. This case is based on a field layout for a plant similar to the PS10 solar tower plant in Spain. In this case, an improvement of the annual intercepted energy into the receiver of about 0.8% was achieved, by slightly repositioning the heliostats. Application of the refinement method is recommended for any future solar tower plant. Basically, the optimization improves the revenues while capital and O&M cost remain unchanged. It is expected that any standard heliostat layout can be improved to a certain degree using this method. The method is very flexible and can be easily adapted to specific situations and optimization goals.
Embedding Desired Eigenstates into Active and Passive Dynamics of a Linear, Underactuated Feedback System
Authors: Saunders Frank , Rife Jason
Published: August 2013

This paper introduces a novel methodology to embed desired reference trajectories into the modal dynamics of an underactuated system through eigenstructure assignment. A unique characteristic of the method is that it decomposes the control input into two parts: an open loop, periodic excitation signal, and a closed loop feedback signal. The periodic excitation causes the system’s natural modes to resonate in a fashion that matches the desired trajectory; modal dynamics, determined by the system’s eigenstates (eigenvectors and their corresponding eigenvalues), are shaped by tuning physical and control parameters concurrently. The method requires the solution of a dual-domain eigenstate factorization problem, in which it is necessary to compute certain unknown elements of a matrix and of its eigenvectors at the same time.
The Synthesis of Spherical Motion Generators in the Presence of an Incomplete Set of Attitudes
Authors: Al-Widyan Khalid , Angeles Jorge
Published: August 2013

Proposed in this paper is a general methodology applicable to the synthesis of spherical motion generators in the presence of an incomplete set of finitely separated attitudes. The spherical rigid-body guidance problem in the realm of four-bar linkage synthesis can be solved exactly for up to five prescribed attitudes of the coupler link, and hence, any number of attitudes smaller than five is considered incomplete in this paper. The attitudes completing the set are determined to produce a linkage whose performance is robust against variations in the unprescribed attitudes. Robustness is needed in this context to overcome the presence of uncertainty due to the selection of the unspecified attitudes, that many a time are specified implicitly by the designer upon choosing, for example, the location of the fixed joints of the dyads. A theoretical framework for model-based robust engineering design is thus, recalled, and a methodology for the robust synthesis of spherical four-bar linkages is laid down. An example is included here to concretize the concepts and illustrate the application of the proposed methodology.
Characterization and Modeling of Elastomeric Joints in Miniature Compliant Mechanisms
Authors: Vogtmann Dana E. , Gupta Satyandra K. , Bergbreiter Sarah
Published: August 2013

Accurate analysis models are critical for effectively utilizing elastomeric joints in miniature compliant mechanisms. This paper presents work toward the characterization and modeling of miniature elastomeric hinges. Characterization was carried out in the form of several experimental bending tests and tension tests on representative hinges in five different configurations. The modeling portion is achieved using a planar pseudo rigid body (PRB) analytical model for these hinges. A simplified planar 3-spring PRB analytical model was developed, consisting of a torsional spring, an axial spring, and another torsional spring in series. These analytical models enable the efficient exploration of large design spaces. The analytical model has been verified to within an accuracy of 3% error in pure bending, and 7% in pure tension, when compared to finite element analysis (FEA) models. Using this analytical model, a complete mechanism—a robotic leg consisting of four rigid links and four compliant hinges—has been analyzed and compared to a corresponding FEA model and a fabricated mechanism.
Nonlocal Modeling and Swarm-Based Design of Heat Sinks
Authors: Geb David , Catton Ivan
Published: August 2013

Cooling electronic chips to satisfy the ever-increasing heat transfer demands of the electronics industry is a perpetual challenge. One approach to addressing this is through improving the heat rejection ability of air-cooled heat sinks, and nonlocal thermal-fluid-solid modeling based on volume averaging theory (VAT) has allowed for significant strides in this effort. A number of optimization methods for heat sink designers who model heat sinks with VAT can be envisioned due to VAT's singular ability to rapidly provide solutions, when compared to computational fluid dynamics (CFD) approaches. The particle swarm optimization (PSO) method appears to be an attractive multiparameter heat transfer device optimization tool; however, it has received very little attention in this field compared to its older population-based optimizer cousin, the genetic algorithm (GA). The PSO method is employed here to optimize smooth and scale-roughened straight-fin heat sinks modeled with VAT by minimizing heat sink thermal resistance for a specified pumping power. A new numerical design tool incorporates the PSO method with a VAT-based heat sink solver. Optimal designs are obtained with this new tool for both types of heat sinks, the performances of the heat sink types are compared, the performance of the PSO method is discussed with reference to the GA method, and it is observed that this new method yields optimal designs much quicker than traditional approaches. This study demonstrates, for the first time, the effectiveness of combining a VAT-based nonlocal thermal-fluid-solid model with population-based optimization methods, such as PSO, to design heat sinks for electronics cooling applications. The VAT-based nonlocal modeling method provides heat sink design capabilities, in terms of solution speed and model rigor, that existing modeling methods do not match.
A parameterization method and application in breast tomosynthesis dosimetry
Authors: Li Xinhua , Zhang Da , Liu Bob
Published: August 2013

Purpose:

To present a parameterization method based on singular value decomposition (SVD), and to provide analytical parameterization of the mean glandular dose (MGD) conversion factors from eight references for evaluating breast tomosynthesis dose in the Mammography Quality Standards Act (MQSA) protocol and in the UK, European, and IAEA dosimetry protocols.

Methods:

MGD conversion factor is usually listed in lookup tables for the factors such as beam quality, breast thickness, breast glandularity, and projection angle. The authors analyzed multiple sets of MGD conversion factors from the Hologic Selenia Dimensions quality control manual and seven previous papers. Each data set was parameterized using a one‐ to three‐dimensional polynomial function of 2–16 terms. Variable substitution was used to improve accuracy. A least‐squares fit was conducted using the SVD.

Results:

The differences between the originally tabulated MGD conversion factors and the results computed using the parameterization algorithms were (a) 0.08%–0.18% on average and 1.31% maximum for the Selenia Dimensions quality control manual, (b) 0.09%–0.66% on average and 2.97% maximum for the published data by Dance et al. [Phys. Med. Biol. 35, – (1990) 10.1088/0031‐9155/35/9/002; Dance et al. Phys. Med. Biol. 45, 3225–3240 (2000) 10.1088/0031‐9155/45/11/308; Dance et al. Phys. Med. Biol. 54, 4361–4372 (2009) 10.1088/0031‐9155/54/14/002; Dance et al. Phys. Med. Biol. 56, 453–471 (2011)] 10.1088/0031‐9155/56/2/011, (c) 0.74%–0.99% on average and 3.94% maximum for the published data by Sechopoulos et al. [Med. Phys. 34, 221–232 (2007)10.1118/1.2400836; Sechopoulos et al. J. Appl. Clin. Med. Phys. 9, 161–171 (2008)] 10.1120/jacmp.v9i4.2887, and (d) 0.66%–1.33% on average and 2.72% maximum for the published data by Feng and Sechopoulos [Radiology 263, 35–42 (2012)] 10.1148/radiol.11111789, excluding one sample in (d) that does not follow the trends in the published data table.

Conclusions:

A flexible parameterization method is presented in this paper, and was applied to breast tomosynthesis dosimetry. The resultant data offer easy and accurate computations of MGD conversion factors for evaluating mean glandular breast dose in the MQSA protocol and in the UK, European, and IAEA dosimetry protocols. Microsoft Excel™ spreadsheets are provided for the convenience of readers.
Real‐time soft tissue motion estimation for lung tumors during radiotherapy delivery
Authors: Rottmann Joerg , Keall Paul , Berbeco Ross
Published: August 2013

Purpose:

To provide real‐time lung tumor motion estimation during radiotherapy treatment delivery without the need for implanted fiducial markers or additional imaging dose to the patient.

Methods:

2D radiographs from the therapy beam's‐eye‐view (BEV) perspective are captured at a frame rate of 12.8 Hz with a frame grabber allowing direct RAM access to the image buffer. An in‐house developed real‐time soft tissue localization algorithm is utilized to calculate soft tissue displacement from these images in real‐time. The system is tested with a Varian TX linear accelerator and an AS‐1000 amorphous silicon electronic portal imaging device operating at a resolution of 512 × 384 pixels. The accuracy of the motion estimation is verified with a dynamic motion phantom. Clinical accuracy was tested on lung SBRT images acquired at 2 fps.

Results:

Real‐time lung tumor motion estimation from BEV images without fiducial markers is successfully demonstrated. For the phantom study, a mean tracking error <1.0 mm [root mean square (rms) error of 0.3 mm] was observed. The tracking rms accuracy on BEV images from a lung SBRT patient (≈20 mm tumor motion range) is 1.0 mm.

Conclusions:

The authors demonstrate for the first time real‐time markerless lung tumor motion estimation from BEV images alone. The described system can operate at a frame rate of 12.8 Hz and does not require prior knowledge to establish traceable landmarks for tracking on the fly. The authors show that the geometric accuracy is similar to (or better than) previously published markerless algorithms not operating in real‐time.
Total target volume is a better predictor of whole brain dose from gamma stereotactic radiosurgery than the number, shape, or location of the lesions
Authors: Narayanasamy Ganesh , Smith Adam , Van Meter Emily , McGarry Ronald , Molloy Janelle A.
Published: August 2013

Purpose:

To assess the hypothesis that the volume of whole brain that receives a certain dose level is primarily dependent on the treated volume rather than on the number, shape, or location of the lesions. This would help a physician validate the suitability of GammaKnife® based stereotactic radiosurgery (GKSR) prior to treatment.

Methods:

Simulation studies were performed to establish the hypothesis for both oblong and spherical shaped lesions of various numbers and sizes. Forty patients who underwent GKSR [mean age of 54 years (range 7–80), mean number of lesions of 2.5 (range 1–6), and mean lesion volume of 4.4 cm3 (range 0.02–22.2 cm3)] were also studied retrospectively. Following recommendations of QUANTEC, the volume of brain irradiated by the 12 Gy (VB12) isodose line was measured and a power‐law based relation is proposed here for estimating VB12 from the known tumor volume and the prescription dose.

Results:

In the simulation study on oblong, spherical, and multiple lesions, the volume of brain irradiated by 50%, 10%, and 1% of maximum dose was found to have linear, linear, and exponentially increasing dependence on the volume of the treated region, respectively. In the retrospective study on 40 GKSR patients, a similar relationship was found to predict the brain dose with a Spearman correlation coefficient >0.9. In both the studies, the volume of brain irradiated by a certain dose level does not have a statistically significant relationship (p ≥ 0.05) with the number, shape, or position of the lesions. The measured VB12 agrees with calculation to within 1.7%.

Conclusions:

The results from the simulation and the retrospective clinical studies indicate that the volume of whole brain that receives a certain percentage of the maximum dose is primarily dependent on the treated volume and less on the number, shape, and location of the lesions.
Unsteady numerical simulation of a round jet with impinging microjets for noise suppression
Authors: Lew Phoi-Tack , Najafi-Yazdi Alireza , Mongeau Luc
Published: August 2013

The objective of this study was to determine the feasibility of a lattice-Boltzmann method (LBM)-Large Eddy Simulation methodology for the prediction of sound radiation from a round jet-microjet combination. The distinct advantage of LBM over traditional computational fluid dynamics methods is its ease of handling problems with complex geometries. Numerical simulations of an isothermal Mach 0.5, ReD = 1 × 105 circular jet (Dj = 0.0508 m) with and without the presence of 18 microjets (Dmj = 1 mm) were performed. The presence of microjets resulted in a decrease in the axial turbulence intensity and turbulent kinetic energy. The associated decrease in radiated sound pressure level was around 1 dB. The far-field sound was computed using the porous Ffowcs Williams-Hawkings surface integral acoustic method. The trend obtained is in qualitative agreement with experimental observations. The results of this study support the accuracy of LBM based numerical simulations for predictions of the effects of noise suppression devices on the radiated sound power.
Assessment of systematic measurement errors for acoustic travel-time tomography of the atmosphere
Authors: Vecherin Sergey N. , Ostashev Vladimir E. , Wilson D. Keith
Published: August 2013

Two algorithms are described for assessing systematic errors in acoustic travel-time tomography of the atmosphere, the goal of which is to reconstruct the temperature and wind velocity fields given the transducers' locations and the measured travel times of sound propagating between each speaker-microphone pair. The first algorithm aims at assessing the errors simultaneously with the mean field reconstruction. The second algorithm uses the results of the first algorithm to identify the ray paths corrupted by the systematic errors and then estimates these errors more accurately. Numerical simulations show that the first algorithm can improve the reconstruction when relatively small systematic errors are present in all paths. The second algorithm significantly improves the reconstruction when systematic errors are present in a few, but not all, ray paths. The developed algorithms were applied to experimental data obtained at the Boulder Atmospheric Observatory.
Interacting bubble clouds and their sonochemical production
Authors: Stricker Laura , Dollet Benjamin , Fernández Rivas David , Lohse Detlef
Published: August 2013

An acoustically driven air pocket trapped in a pit etched on a surface can emit a bubble cluster. When several pits are present, the resulting bubble clusters interact in a nontrivial way. Fernández Rivas et al. [Angew. Chem. Int. Ed. 49, 9699–9701 (2010)] observed three different behaviors at increasing driving power: clusters close to their “mother” pits, clusters attracting each other but still well separated, and merging clusters. The last is highly undesirable for technological purposes as it is associated with a reduction of the radical production and an enhancement of the erosion of the reactor walls. In this paper, the conditions for merging to occur are quantified in the case of two clusters, as a function of the following control parameters: driving pressure, distance between the two pits, cluster radius, and number of bubbles within each cluster. The underlying mechanism, governed by the secondary Bjerknes forces, is strongly influenced by the nonlinearity of the bubble oscillations and not directly by the number of nucleated bubbles. The Bjerknes forces are found to dampen the bubble oscillations, thus reducing the radical production. Therefore, the increased number of bubbles at high power could be the key to understanding the experimental observation that, above a certain power threshold, any further increase of the driving does not improve the sonochemical efficiency.
Role and relative contribution of temporal envelope and fine structure cues in sentence recognition by normal-hearing listeners
Authors: Apoux Frédéric , Yoho Sarah E. , Youngdahl Carla L. , Healy Eric W.
Published: August 2013

The present study investigated the role and relative contribution of envelope and temporal fine structure (TFS) to sentence recognition in noise. Target and masker stimuli were added at five different signal-to-noise ratios (SNRs) and filtered into 30 contiguous frequency bands. The envelope and TFS were extracted from each band by Hilbert decomposition. The final stimuli consisted of the envelope of the target/masker sound mixture at x dB SNR and the TFS of the same sound mixture at y dB SNR. A first experiment showed a very limited contribution of TFS cues, indicating that sentence recognition in noise relies almost exclusively on temporal envelope cues. A second experiment showed that replacing the carrier of a sound mixture with noise (vocoder processing) cannot be considered equivalent to disrupting the TFS of the target signal by adding a background noise. Accordingly, a re-evaluation of the vocoder approach as a model to further understand the role of TFS cues in noisy situations may be necessary. Overall, these data are consistent with the view that speech information is primarily extracted from the envelope while TFS cues are primarily used to detect glimpses of the target.
Ultrasonic wave propagation in thermoviscous moving fluid confined by heating pipeline and flow measurement performance
Authors: Chen Yong , Huang Yiyong , Chen Xiaoqian
Published: August 2013

Ultrasonic wave propagation in thermoviscous fluid with pipeline shear mean flow in the presence of a temperature gradient is investigated. On the assumption of irrotational and axisymmetric wave propagation, a mathematical formulation of the convected wave equation is proposed without simplification in the manner of Zwikker and Kosten. A method based on the Fourier–Bessel theory, which is complete and orthogonal in Lebesgue space, is introduced to convert the wave equations into homogeneous algebraic equations. Then numerical calculation of the axial wavenumber is presented. In the end, wave attenuation in laminar and turbulent flow is numerically studied. Meanwhile measurement performance of an ultrasonic flow meter is parametrically analyzed.
Measuring the effect of ambient noise directionality and split-beam processing on the convergence of the cross-correlation function
Authors: Fried Stephanie E. , Walker Shane C. , Hodgkiss William S. , Kuperman W. A.
Published: August 2013

Measurements of ambient noise have been used to infer information about the ocean acoustic environment. In recent years the correlation of ambient noise has been shown to give estimates of the travel time of acoustic paths between the sensors recording the noise. A number of issues affect the results of the noise correlation. This paper presents the results of noise correlation of the two horizontally separated arrays of sensors in the 2010 ambient noise experiment. Using the experimental data, the effects on the convergence of the noise correlation are examined with respect to the size and shape of the arrays, the length of time used, and the directionality of the noise field.
Using automatic alignment to analyze endangered language data: Testing the viability of untrained alignment
Authors: DiCanio Christian , Nam Hosung , Whalen Douglas H. , Timothy Bunnell H. , Amith Jonathan D. , García Rey Castillo
Published: August 2013

While efforts to document endangered languages have steadily increased, the phonetic analysis of endangered language data remains a challenge. The transcription of large documentation corpora is, by itself, a tremendous feat. Yet, the process of segmentation remains a bottleneck for research with data of this kind. This paper examines whether a speech processing tool, forced alignment, can facilitate the segmentation task for small data sets, even when the target language differs from the training language. The authors also examined whether a phone set with contextualization outperforms a more general one. The accuracy of two forced aligners trained on English (hmalign and p2fa) was assessed using corpus data from Yoloxóchitl Mixtec. Overall, agreement performance was relatively good, with accuracy at 70.9% within 30 ms for hmalign and 65.7% within 30 ms for p2fa. Segmental and tonal categories influenced accuracy as well. For instance, additional stop allophones in hmalign's phone set aided alignment accuracy. Agreement differences between aligners also corresponded closely with the types of data on which the aligners were trained. Overall, using existing alignment systems was found to have potential for making phonetic analysis of small corpora more efficient, with more allophonic phone sets providing better agreement than general ones.