bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimal transseptal puncture location for robot‐assisted left atrial catheter ablation
Authors: Jayender J. , Patel R. V. , Michaud G. F. , Hata N.
Published: April 2011

Background

The preferred method of treatment for atrial fibrillation (AF) is by catheter ablation, in which a catheter is guided into the left atrium through a transseptal puncture. However, the transseptal puncture constrains the catheter, thereby limiting its manoeuvrability and increasing the difficulty in reaching various locations in the left atrium. In this paper, we address the problem of choosing the optimal transseptal puncture location for performing cardiac ablation to obtain maximum manoeuvrability of the catheter.

Methods

We have employed an optimization algorithm to maximize the global isotropy index (GII) to evaluate the optimal transseptal puncture location. As part of this algorithm, a novel kinematic model for the catheter has been developed, based on a continuum robot model. Pre‐operative MR/CT images of the heart are segmented using the open source image‐guided therapy software, 3D Slicer, to obtain models of the left atrium and septal wall. These models are input to the optimization algorithm to evaluate the optimal transseptal puncture location.

Results

The continuum robot model accurately describes the kinematics of the catheter. Simulation and experimental results for the optimal transseptal puncture location are presented in this paper. The optimization algorithm generates discrete points on the septal wall for which the dexterity of the catheter in the left atrium is maximum, corresponding to a GII of 0.4362.

Conclusion

We have developed an optimization algorithm based on the GII to evaluate the optimal position of the transseptal puncture for left atrial cardiac ablation. Copyright © 2011 John Wiley & Sons, Ltd.
Viruses and the fuel sensor: the emerging link between AMPK and virus replication
Authors: Mankouri Jamel , Harris Mark
Published: April 2011

Adenosine 5′ monophosphate‐activated protein kinase (AMPK) is conserved in all eukaryotic cells and functions as the key regulator of cellular metabolism by responding to the energy status of the cell. It is activated by an increase in the AMP : ATP ratio and then attempts to redress the balance by upregulating catabolic processes, whilst concomitantly inhibiting anabolic processes. Despite its critical importance in the functioning of eukaryotic cells, there has been a paucity of studies investigating the potential for dysregulation of AMPK by viruses. Recently, however, there have been a number of reports that have begun to address this gap in our knowledge. In this article, we will review this emerging field, outlining how a variety of viruses have been shown to either stimulate or inhibit AMPK activity. We will also document the effects of these perturbations on the biology of virus infection, in particular with regard to the ability of viruses to persist or cause cytopathogenesis. Copyright © 2011 John Wiley & Sons, Ltd.
Viruses as key regulators of angiogenesis
Authors: Vrancken Kristof , Vervaeke Peter , Balzarini Jan , Liekens Sandra
Published: April 2011

Angiogenesis is an important physiological process that is controlled by a precise balance of growth and inhibitory factors in healthy tissues. However, environmental and genetic factors may disturb this delicate balance, resulting in the development of angiogenic diseases, tumour growth and metastasis. During the past decades, extensive research has led to the identification and characterization of genes, proteins and signalling pathways that are involved in neovascularization. Moreover, increasing evidence indicates that viruses may also regulate angiogenesis either directly, by (i) producing viral chemokines, growth factors and/or receptors or (ii) activating blood vessels as a consequence of endothelial cell tropism, or indirectly, by (iii) modulating the activity of cellular proteins and/or (iv) inducing a local or systemic inflammatory response, thereby creating an angiogenic microenvironment. As such, viruses may modulate several signal transduction pathways involved in angiogenesis leading to changes in endothelial cell proliferation, migration, adhesion, vascular permeability and/or protease production. Here, we will review different mechanisms that may be applied by viruses to deregulate the angiogenic balance in healthy tissues and/or increase the angiogenic potential of tumours. Copyright © 2011 John Wiley & Sons, Ltd.
Anti‐windup strategy for reset control systems
Authors: Tarbouriech Sophie , Loquen Thomas , Prieur Christophe
Published: April 2011

This paper proposes an anti‐windup strategy to deal with stability and performance requirements for a class of hybrid systems, such as those including a reset controller and subject to input saturation. The computation of the anti‐windup compensator aiming at ensuring both ℒ︁2 input‐to‐state stability and internal stability of the closed‐loop system is carried out from the solution of matrix inequalities. Depending on the way chosen to describe reset rules, the conditions for designing the anti‐windup compensator are expressed through nonlinear matrix inequalities or linear matrix inequalities. Some optimization criteria in both cases are considered for the synthesis purpose: maximization of the ℒ︁2‐norm upper bound on the admissible disturbances for which the trajectories are assured to be bounded; minimization of the ℒ︁2‐gain of the disturbance to the system‐to‐be‐controlled output; and the maximization of an estimate of the domain of attraction of the origin. Copyright © 2011 John Wiley & Sons, Ltd.
A comparison of one‐class bag‐of‐words user behavior modeling techniques for masquerade detection
Authors: Salem Malek Ben , Stolfo Salvatore J.
Published: April 2011

A masquerade attack is a consequence of identity theft. In such attacks, the impostor impersonates a legitimate insider while performing illegitimate activities. These attacks are very hard to detect and can cause considerable damage to an organization. Prior work has focused on user command modeling to identify abnormal behavior indicative of impersonation. In this paper, we investigate the performance of two one‐class user behavior profiling techniques: one‐class Support Vector Machines (ocSVMs) and a Hellinger distance‐based user behavior profiling technique. Both techniques model bags of words or commands and do not model sequences of commands. We use both techniques for masquerade detection and compare the experimental results. The objective is to evaluate which modeling technique is most suitable for use in an operational monitoring system, hence our focus is on accuracy and operational performance characteristics. We show that one‐class SVMs are most practical for deployment in sensors developed for masquerade detection in the general case. We also show that for specific users whose profile fits the average user profile, one‐class SVMs may not be the best modeling approach. Such users pose a more serious threat since they may be easier to mimic. Copyright © 2011 John Wiley & Sons, Ltd.
Simple preparation routes for corrosion protection hybrid sol‐gel coatings on AA 2024
Authors: Wittmar A. , Caparrotti H. , Wittmar M. , Veith M.
Published: April 2011

In recent years, many hybrid inorganic‐organic systems have been proposed in order to replace the traditional conversion coatings on metals like aluminum, and some results have been promising. However, many proposed solutions are based on complicated processes which are not easy to be adapted to industrial scale. The aim of this study was to establish a simple process leading to the production of highly efficient corrosion protective hybrid sol‐gel coating systems for the aluminum alloys as replacement for the highly hazardous conventional chromate conversion coatings. Hybrid coatings have been realized by means of the sol‐gel process. CeO2 and ZnO have been introduced as dispersions of nanoparticles in the system and used as corrosion inhibitors. The aim of this work was to obtain pore‐free coatings with increased barrier properties using nanoparticles that possess the double function of pore fillers and corrosion inhibitors. The proposed processes led to coating materials with good adherence to the aluminum substrate and an extremely long life in the accelerated neutral salt spray test according to DIN ISO 9227. Electrochemical impedance spectroscopy approves these results by high impedance values in the low‐frequency region of the Bode plot. Copyright © 2011 John Wiley & Sons, Ltd.
Förster Resonance Energy Transfer in Quantum Dot–Dye‐Loaded Zeolite L Nanoassemblies
Authors: Ramachandra Srinidhi , Popovic′ Zoran D. , Schuermann Klaus C. , Cucinotta Fabio , Calzaferri Gion , De Cola Luisa
Published: April 2011

Nanoassemblies formed by coating a dye‐loaded zeolite L surface with CdSe/ZnS core/shell quantum dots (QDs) is described. A photoinduced energy transfer is observed from the excited QDs, which are on the surface of the zeolite crystals, to dye molecules (energy acceptors) encapsulated and aligned in the 1D channels of the aluminosilicate host. Steady‐state and time‐resolved spectroscopy and microscopy are used to quantify the Förster resonance energy transfer occurring through electronic transition dipole interactions between the QDs and the oxonine‐loaded zeolite L crystals. For the first time the energy transfer in artificial antenna systems based on quantum dots and molecules hosted in inert systems is described.
Nanostructuring Polymeric Materials by Templating Strategies
Authors: Knoll Wolfgang , Caminade Anne‐Marie , Char Kookheon , Duran Hatice , Feng Chuan Liang , Gitsas Antonis , Kim Dong Ha , Lau Aaron , Lazzara Thomas D. , Majoral Jean‐Pierre , Steinhart Martin , Yameen Basit , Zhong X. H.
Published: April 2011

This contribution summarizes efforts in designing, assembling/synthesizing, and structurally and functionally characterizing nanostructured materials using anodized aluminum oxide (AAO) as a thin‐film template. Optical waveguide spectroscopy, using a nanoporous template as the guiding structure, is a particularly powerful analytical tool. The layer‐by‐layer approach for the fabrication of multilayer assemblies is shown to allow the fabrication of nanotube arrays. In addition to using dendrimers as building blocks, semiconducting nanomaterial (e.g., quantum dot) hybrid architectures with very interesting photophysical properties can be assembled. These can be employed, for example, in biosensing applications. Other strategies for using the AAO layers as templates include the growth of polymeric nanorod arrays from different functional monomers, which, after the dissolution of the template, are still able to guide light. This opens up novel concepts for integrated optics platforms with nanostructured materials.
Micro‐/Nano‐engineered Cellular Responses for Soft Tissue Engineering and Biomedical Applications
Authors: Tay Chor Yong , Irvine Scott Alexander , Boey Freddy Y. C. , Tan Lay Poh , Venkatraman Subbu
Published: April 2011

The development of biomedical devices and reconstruction of functional ex vivo tissues often requires the need to fabricate biomimetic surfaces with features of sub‐micrometer precision. This can be achieved with the advancements in micro‐/nano‐engineering techniques, allowing researchers to manipulate a plethora of cellular behaviors at the cell–biomaterial interface. Systematic studies conducted on these 2D engineered surfaces have unraveled numerous novel findings that can potentially be integrated as part of the design consideration for future 2D and 3D biomaterials and will no doubt greatly benefit tissue engineering. In this review, recent developments detailing the use of micro‐/nano‐engineering techniques to direct cellular orientation and function pertinent to soft tissue engineering will be highlighted. Particularly, this article aims to provide valuable insights into distinctive cell interactions and reactions to controlled surfaces, which can be exploited to understand the mechanisms of cell growth on micro‐/nano‐engineered interfaces, and to harness this knowledge to optimize the performance of 3D artificial soft tissue grafts and biomedical applications.
Decreased fetal cardiac performance in the first trimester correlates with hyperglycemia in pregestational maternal diabetes
Authors: Turan S. , Turan O. M. , Miller J. , Harman C. , Reece E. A. , Baschat A. A.
Published: April 2011

Objective

In‐vitroanimal studies suggest that high glucose levels impair fetal cardiac function early in gestation. We aimed to study whether evidence of first‐trimester myocardial dysfunction can be detected in fetuses of women with pregestational diabetes mellitus.

Methods

Women with diabetes mellitus underwent fetal echocardiography at 11–14 weeks' gestational age. In fetuses with normal anatomy, the cardiac preload, diastolic function, global myocardial performance and placental afterload were studied by Doppler of the ductus venosus (DV), mitral and tricuspid early/atrial (E/A) ratios, left and right ventricular myocardial performance index (MPI) and umbilical artery (UA) Doppler, respectively. Cases were matched for gestational age and UA and DV Doppler with controls that had no diabetes mellitus.

Results

Sixty‐three singleton diabetic pregnancies were matched with 63 controls. Mean gestational age at enrollment was 12.6 (range, 11.1–13.6) weeks. Diabetic mothers had moderate to poor glycemic control (median (range) glycosylated hemoglobin A1 (HbA1c), 7.5 (5.1–12.7)%, and the HbA1c level was ≥ 7% in 37 (59%)). Fetuses of diabetic mothers exhibited worse measures of diastolic dysfunction: the isovolumetric relaxation time (IRT) was significantly prolonged (left ventricle: 36.9 ± 7.4 ms vs. 45.8 ± 6.8 ms; right ventricle: 35.6 ± 8 ms vs. 46.4 ± 7.3 ms,P< 0.0001 for both). The mitral E/A ratio was lower in diabetics (0.55 ± 0.06 vs. 0.51 ± 0.08,P= 0.03), and the global myocardial performance was lower in both ventricles (left ventricle MPI: 0.5 ± 0.08; right ventricle MPI: 0.52 ± 0.08,P= 0.03 andP< 0.0001, respectively). This lower global myocardial performance was caused by a prolonged myocardial relaxation time, which was most marked in diabetics with an HbA1c of ≥ 7% (P< 0.001 vs. controls for both ventricles). There were no significant correlations between cardiac Doppler parameters and DV, UA indices and fetal heart rate (P> 0.05 for all).

Conclusions

Fetuses of poorly controlled diabetic mothers demonstrate significant differences in first‐trimester diastolic myocardial function compared with non‐diabetic controls. The decrease in myocardial performance is more marked with increasing HbA1c and appears to be independent of preload and afterload. The ability to document these cardiac functional changes this early in pregnancy opens potential new avenues to understand the consequences of maternal glycemic status. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.
Prediction of intrauterine fetal death in small‐forgestational‐age fetuses: impact of including ultrasound biometry in customized models
Authors: Odibo A. O. , Cahill A. G. , Odibo L. , Roehl K. , Macones G. A.
Published: April 2011

Objective

Customized growth charts derived from maternal demographic characteristics alone have been shown to improve the prediction of pregnancy complications compared to population growth curves. We sought to estimate the impact of adding ultrasound biometric parameters to the customized chart for the prediction of intrauterine fetal death (IUFD).

Methods

A retrospective cohort study was undertaken using an ultrasound database including singleton pregnancies followed between 16 and 20 weeks' gestation. After exclusion of preterm births, congenital anomalies, multifetal pregnancies and stillbirths (excluded only from derivation samples), we identified 59 016 births, divided into derivation (34 832) and validation (24 184) samples. Coefficients for significant physiological and pathological variables affecting fetal growth were derived using backward stepwise multiple regression (Cust‐chart). The same process was repeated including second‐trimester biometric parameters: biparietal diameter, head circumference, femur length and abdominal circumference in the regression models (Cust‐plus‐USS‐chart). The association between small‐for‐gestational age < 10th centile (SGA) pregnancies, defined using the two customized charts or our population‐based growth chart (Pop‐chart) and IUFD, were compared. Statistical analyses including OR, 95% CI and screening accuracy using each chart were performed.

Results

The derived coefficients for fetal growth are comparable to those of previously published series. Of 24 184 pregnancies in the validation sample, IUFD was seen in 169 (0.7%). The pregnancies identified as SGA were: 2482 (10.26%), 2499 (10.33%) and 2634 (10.89%) using the Cust‐chart, Cust‐plus‐USS‐chart and Pop‐chart, respectively. The OR (95% CI) for the association between SGA defined by the three charts and IUFD was: 7.0 (4.5–11), 6.5 (4.2–10.2) and 2.4 (1.6–3.6) according to the Cust‐chart, Cust‐plus‐USS‐chart and Pop‐chart, respectively. Screening efficiency for IUFD using both customized charts was similar, with both demonstrating a higher sensitivity compared with the Pop‐chart.

Conclusions

Customized charts are more efficient in identifying pregnancies at risk for IUFD compared with population‐based charts. However, adding second‐trimester ultrasound biometric parameters to the customized model does not improve the prediction of IUFD compared with using maternal characteristics only. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.
Early‐stage cervical cancer: agreement between ultrasound and histopathological findings with regard to tumor size and extent of local disease
Authors: Gaurilcikas A. , Vaitkiene D. , Cizauskas A. , Inciura A. , Svedas E. , Maciuleviciene R. , Di Legge A. , Ferrandina G. , Testa A. C. , Valentin L.
Published: April 2011

Objectives

To determine the agreement between ultrasound and histological examination of the cervix in patients with early stage cervical cancer with regard to tumor size and local extent of the disease.

Methods

Eighteen patients with histologically proven cervical cancer Stage IB1–IIA according to traditional clinical staging (FIGO 1988) who were scheduled for radical surgery underwent a standardized transvaginal ultrasound examination. The maximum tumor length, anteroposterior tumor diameter, tumor width, tumor area, depth of cervical stroma invasion, and the minimal thickness of tumor‐free cervical stroma on sagittal and transverse planes through the cervix were measured, and the local extent of the disease within the parametria and vagina were evaluated. The surgical specimens were examined using a specifically devised method of histopathological examination. The results of the ultrasound and histopathological examinations were compared.

Results

Limits of agreement were wide and the intraclass correlation coefficient (ICC) was low (0.51–0.58) for three of the four measurements taken to represent the minimal depth of tumor‐free cervical stroma, i.e. the results of the measurements taken posteriorly and laterally. However, the limits of agreement were narrower and the ICC values were higher (0.74–0.92) for the depth of cervical stroma invasion and for the tumor size measurements. Histological examination revealed parametrial cancer infiltration in four patients, which was detected during ultrasound examination, with no false‐positive results.

Conclusions

Transvaginal sonography is acceptably accurate for evaluation of tumor size and depth of cervical stroma invasion in clinical practice. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.
On the differentiated QoE enforcement between competing scalable video flows over wireless networks
Authors: Goudarzi Pejman
Published: April 2011

In differentiated quality‐of‐experience enforcement (QoE) for video transmission over wireless networks, accurate video quality metrics play a crucial role in the designing process of optimal resource assignment algorithms. Many cross‐layer optimization‐based rate‐allocation strategies, which consider different objective functions (congestion level, total packet loss, etc.), have been developed for this purpose. The main contributions of the proposed work are twofold. Firstly, an optimal resource assignment framework is being developed in which, based on some network‐specific constraints and by incorporating appropriate video quality metrics, the total weighted QoE of some competing scalable video sources is being optimized based on cross‐layer optimization techniques. Secondly, these optimal rates can be used for differentiated QoE enforcement between multiple competing scalable video sources. The resulting optimal rates can be considered as rate feedbacks for online rate adaptation of a moderate scalable video encoder such as H.264/MPEG‐4 advanced video coding. The aforementioned weight parameters are selected based on the importance of each video sequence's quality and can be associated with some previous service level agreement‐based prices. Some numerical analysis have been presented to validate the theoretical results and to verify the claims. Copyright © 2011 John Wiley & Sons, Ltd.
Mining uncertain data
Authors: Leung Carson Kai‐Sang
Published: April 2011

As an important data mining and knowledge discovery task,association rule miningsearches for implicit, previously unknown, and potentially useful pieces of information—in the form of rules revealing associative relationships—that are embedded in the data. In general, the association rule mining process comprises two key steps. The first key step, whichmines frequent patterns(i.e., frequently occurring sets of items) from data, is more computationally intensive than the second key step of using the mined frequent patterns toform association rules. In the early days, many developed algorithms mined frequent patterns from traditional transaction databases of precise data such as shopping market basket data, in which the contents of databases are known. However, we are living in an uncertain world, in which uncertain data can be found almost everywhere. Hence, in recent years, researchers have paid more attention to frequent pattern mining from probabilistic databases of uncertain data. In this paper, we review recent algorithmic development on mining uncertain data in these probabilistic databases for frequent patterns. © 2011 John Wiley & Sons, Inc.WIREs Data Mining Knowl Discov2011 1 316–329 DOI: 10.1002/widm.31

This article is categorized under:

Algorithmic Development > Association Rules
Central Compartment Neck Dissection for Thyroid Cancer: A Surgical Technique
Authors: Hartl Dana M. , Travagli Jean‐Paul
Published: April 2011

Several professional societies have in the past few years joined forces to standardize and define terminology for central compartment neck dissection, with the objective of improving communication among professionals and encouraging a more uniform surgical approach to neck nodes. Precisely defining and describing a technique has the advantage of providing a basis for communication and for discussion. A basic technique should be reproducible with low morbidity and teachable to surgeons in training. We herein describe a basic technique for bilateral central compartment neck dissection for thyroid cancer.
A critique of Bernstein’s beyond objectivism and relativism: science, hermeneutics, and praxis
Authors: Matusitz Jonathan , Kramer Eric
Published: April 2011

This analysis comments on Bernstein’s lack of clear understanding of subjectivity, based on his book, Beyond Objectivism and Relativism: Science, Hermeneutics, and Praxis. Bernstein limits his interpretation of subjectivity to thinkers such as Gadamer and Habermas. The authors analyze the ideas of classic scholars such as Edmund Husserl and Friedrich Nietzsche. Husserl put forward his notion of transcendental subjectivity and phenomenological ramifications of the relationship between subjectivity and objectivity. Nietzsche referred to subjectivity as “perspectivism,” the inescapable fact that any and all consciousnesses exist in space and time. Consciousness is fundamentally constituted of cultural, linguistic, and historical dimensions.
Clinical characterization of patients with macroprolactinemia and monomeric hyperprolactinemia
Authors: Can Murat , Guven Berrak , Atmaca Hulusi , Acıkgoz Serefden , Mungan Gorkem
Published: April 2011

Macroprolactinemia is often a cause of misdiagnosis, unnecessary expensive investigation, and unsuitable treatment. The aim of the present study was to investigate the clinical findings and the concentrations of macroprolactin in patients with hyperprolactinemia in our region. Eighty‐four female hyperprolactinemic patients were screened for macroprolactinemia. Prolactin was measured by chemiluminesans method on an Immulite 2000 analyzer (Siemens Health Diagnostics, Deerfield, IL, USA). Recoveries less than or equal to 40% after polyethylene glycol precipitation were indicative of macroprolactinemia. Clinical features and biochemical values were compared in true hyperprolactinemic and macroprolactinemic patients. Macroprolactinemia was detected in 31 patients (36.9%), with 84 hyperprolactinemic female patients. There was no difference in frequency of galactorrhea and oligomenorrhea/amenorrhea between the two groups. When we evaluated the clinical features of patients according to prolactin levels, no significant difference was found between the groups. In conclusion, our initial data show that no clinical features could reliably differentiate macroprolactinemic from true hyperprolactinemic patients, but at least one of these symptoms was present in most macroprolactinemic patients.
Primary Sjögren's syndrome with minimal change disease—A case report
Authors: Yang Mei‐Li , Kuo Mei‐Chuan , Ou Tsan‐Teng , Chen Hung‐Chun
Published: April 2011

Glomerular involvement in patients with primary Sjögren's syndrome (pSS) has rarely been reported. Among them, membranoproliferative glomerulonephritis and membranous nephropathy are the more common types. We report a middle‐aged female presenting concurrently with nephrotic syndrome and microscopic hematuria, and her pSS was diagnosed by positive anti‐Ro (SSA)/anti‐La (SSB) autoantibodies, dry mouth, severely diffuse impaired function of both bilateral parotid and submandibular glands, and a positive Schirmer test. Renal pathology revealed minimal change disease and thin basement membrane nephropathy. The patient's nephrotic syndrome resolved after treatment with corticosteroids. To our knowledge, this is the first report of minimal change disease in a patient with pSS.
Alcohol drinking triggers acute myocardial infarction in a case of hypertrophic obstructive cardiomyopathy
Authors: Hsu Po‐Chao , Chu Chih‐Sheng , Lin Tsung‐Hsien , Su Ho‐Ming , Yen Hsueh‐Wei , Lai Wen‐Ter , Sheu Sheng‐Hsiung
Published: April 2011

Alcohol ingestion–related increased left ventricular outflow tract (LVOT) pressure gradient in hypertrophic obstructive cardiomyopathy (HOCM) has been reported in the literature; however, acute myocardial infarction (AMI) after alcohol drinking in this patient group is rarely reported. Herein, we report a 68‐year‐old man with chronic alcoholism suffering from AMI after alcohol drinking. Electrocardiography revealed complete left bundle branch block, and chest X‐ray showed acute pulmonary edema. Intubation was done for respiratory failure and intra‐aortic balloon pump was also inserted for unstable hemodynamics. However, emergent coronary angiography revealed normal coronary arteries. HOCM was diagnosed by a high pressure gradient over LVOT and systolic anterior motion of mitral valve by echocardiography. This patient became stable under intensive care and medical treatment. This case reminds physicians that alcohol ingestion might cause AMI in HOCM patients because of increased LVOT pressure gradient and decreased coronary perfusion despite normal coronary arteries.
Expression of manganese superoxide dismutase in patients with breast cancer
Authors: Tsai Shih‐Meng , Hou Ming‐Feng , Wu Szu‐Hsien , Hu Bao‐Wen , Yang Sheau‐Fang , Chen Wan‐Tzu , Chai Chee‐Yin , Ma Hsu , Tsai Li‐Yu
Published: April 2011

Breast cancer has become the second leading cancer among females in Taiwan. Even though the etiology of breast cancer is multifactorial, oxidative stress plays an important role in the carcinogenesis. The purpose of this study was to investigate the expression of manganese superoxide dismutase (MnSOD), one of the major antioxidant enzymes that is involved against oxidative stress, in adjacent cancer‐free breast tissues and neoplasm tissues within the same patient. Sixty‐five breast cancer patients' formalin‐fixed tissue blocks, including ductal carcinoma in situ (DCIS) tissues, invasive ductal carcinoma (IDC) tissues, and adjacent cancer‐free tissues, were evaluated by immunohistochemical stain. Meanwhile, their demographic and clinical information was also collected. The combined scores of MnSOD‐positive cell proportion and MnSOD staining intensity were compared for different tissues within the same patient. The results showed that the mean combined scores of MnSOD expression in adjacent cancer‐free tissues (6.33), IDC (5.30), and DCIS (3.78) were significantly different when assessed by repeated‐measurement analysis of variance (F = 14.17, p < 0.001). Additionally, the results revealed that the distribution of strong MnSOD protein expression was 80.0%, 72.3%, and 52.3% in adjacent cancer‐free tissues, IDC, and DCIS, respectively. However, there was no statistically significant relationship between the expression of MnSOD and grades of breast cancer or other clinicopathologic variables. We suggest that the expression of MnSOD in neoplasm tissues, independent of the clinicopathologic characters, plays a critical role in breast cancer biology.
Models of non-Boussinesq lock-exchange flow
Authors: ROTUNNO R. , KLEMP J. B. , BRYAN G. H. , MURAKI D. J.
Published: April 2011

Nearly all analytical models of lock-exchange flow are based on the shallow-water approximation. Since the latter approximation fails at the leading edges of the mutually intruding fluids of lock-exchange flow, solutions to the shallow-water equations can be obtained only through the specification of front conditions. In the present paper, analytic solutions to the shallow-water equations for non-Boussinesq lock-exchange flow are given for front conditions deriving from free-boundary arguments. Analytic solutions are also derived for other proposed front conditions – conditions which appear to the shallow-water system as forced boundary conditions. Both solutions to the shallow-water equations are compared with the numerical solutions of the Navier–Stokes equations and a mixture of successes and failures is recorded. The apparent success of some aspects of the forced solutions of the shallow-water equations, together with the fact that in a real fluid the density interface is a free boundary, shows the need for an improved theory of lock-exchange flow taking into account non-hydrostatic effects for density interfaces intersecting rigid boundaries.
The influence of the inertially dominated outer region on the rheology of a dilute dispersion of low-Reynolds-number drops or rigid particles
Authors: SUBRAMANIAN GANESH , KOCH DONALD L. , ZHANG JINGSHENG , YANG CHAO
Published: April 2011

We calculate the rheological properties of a dilute emulsion of neutrally buoyant nearly spherical drops at O(φRe3/2) in a simple shear flow(u∞ = x211, being the shear rate) as a function of the ratio of the dispersed- and continuous-phase viscosities (λ = /μ). Here, φ is the volume fraction of the dispersed phase and Re is the micro-scale Reynolds number. The latter parameter is a dimensionless measure of inertial effects on the scale of the dispersed-phase constituents and is defined as Re = a2ρ/μ, a being the drop radius and ρ the common density of the two phases. The analysis is restricted to the limit φ, Re ≪ 1, when hydrodynamic interactions between drops may be neglected, and the velocity field in a region around the drop of the order of its own size is governed by the Stokes equations at leading order. The dominant contribution to the rheology at O(φRe3/2), however, arises from the so-called outer region where the leading-order Stokes approximation ceases to be valid. The relevant length scale in this outer region, the inertial screening length, results from a balance of convection and viscous diffusion, and is O(aRe−1/2) for simple shear flow in the limit Re ≪ 1. The neutrally buoyant drop appears as a point-force dipole on this scale. The rheological calculation at O(φRe3/2) is therefore based on a solution of the linearized Navier–Stokes equations forced by a point dipole. The principal contributions to the bulk rheological properties at this order arise from inertial corrections to the drop stresslet and Reynolds stress integrals. The theoretical calculations for the stresslet components are validated via finite volume simulations of a spherical drop at finite Re; the latter extend up to Re ≈ 10.

Combining the results of our O(φRe3/2) analysis with the known rheology of a dilute emulsion to O(φRe) leads to the following expressions for the relative viscosity (μe), and the non-dimensional first (N1) and second normal stress differences (N2) to O(φRe3/2): μe = 1 + φ[(5λ+2)/(2(λ+1))+0.024Re3/2(5λ+2)2/(λ+1)2]; N1=φ[−Re4(3λ2+3λ+1)/(9(λ+1)2)+0.066Re3/2(5λ+2)2/(λ+1)2] and N2 = φ[Re2(105λ2+96λ+35)/(315(λ+1)2)−0.085Re3/2(5λ+2)2/(λ+1)2].

Thus, for small but finite Re, inertia endows an emulsion with a non-Newtonian rheology even in the infinitely dilute limit, and in particular, our calculations show that, aside from normal stress differences, such an emulsion also exhibits a shear-thickening behaviour. The results for a suspension of rigid spherical particles are obtained in the limit λ → ∞.
Photo-gyrotactic bioconvection
Authors: WILLIAMS C. R. , BEES M. A.
Published: April 2011

Many microorganisms exhibit taxes, biased swimming motion relative to a directional stimulus. Aggregations of cells with densities dissimilar to the medium in which they swim can induce hydrodynamic instabilities and bioconvection patterns. Here, three novel and mechanistically distinct models of the interaction of the two dominant taxes in suspensions of swimming phototrophic algae are presented: phototaxis, swimming towards or away from light, and gyrotaxis, a balance between viscous and gravitational torques. The descriptions are accordant with, and extend, recent rational models of bioconvection. In particular, the first model is for photokinesis–gyrotaxis, the second varies the cells' centre-of-mass offset, and the third introduces a reactive phototactic torque associated with the propulsive flagellar apparatus. Equilibria and linear-stability analysis in a layer of finite depth are analysed in detail using analytical and numerical methods. Results indicate that the first two models, despite their different roots, remarkably are in agreement. Penetrative and oscillatory modes are found and explained. Dramatically different behaviour is obtained for the model with phototactic torques: instabilities arise even in the absence of fluid motion due to induced gradients of light intensity. Typically, the response of microorganisms to light is multifaceted and thus some combination of the three models is appropriate. Encouragingly, qualitative agreement is found with recent experimental measurements on the effects of illumination on dominant pattern wavelength in bioconvection experiments. The theory may be of some interest in the emergent field of bioreactor design.
Quasi-three dimensional analysis of global instabilities: onset of vortex shedding behind a wavy cylinder
Authors: GARBARUK A. , CROUCH J. D.
Published: April 2011

In this paper the global-stability theory is extended to account for weak spanwise-flow variations using a quasi-three-dimensional framework. The analysis considers the onset of vortex shedding behind a circular cylinder with a spanwise-varying diameter. The quasi-three-dimensional approach models the fully three-dimensional flow structure as a series of two-dimensional eigenvalue problems representing the sectional-flow behaviour. The sectional results are coupled together using the Ginzburg–Landau equation, which models the diffusive coupling and provides the global response. The onset of global instability (and thus vortex shedding) is linked to both the sectional growth rates (characterized by the maximum-diameter location) and the spanwise extent of the zone of instability. Unsteady numerical simulations are used to guide the global-stability analysis and to assess the fidelity of the predictions. Results from the stability analysis are shown to be in good agreement with the numerical simulations, which are in close agreement with experiments.
Boundary conditions at a rigid wall for rough granular gases
Authors: NOTT PRABHU R.
Published: April 2011

We derive boundary conditions at a rigid wall for a granular material comprising rough, inelastic particles. Our analysis is confined to the rapid flow, or granular gas, regime in which grains interact by impulsive collisions. We use the Chapman–Enskog expansion in the kinetic theory of dense gases, extended for inelastic and rough particles, to determine the relevant fluxes to the wall. As in previous studies, we assume that the particles are spheres, and that the wall is corrugated by hemispheres rigidly attached to it. Collisions between the particles and the wall hemispheres are characterized by coefficients of restitution and roughness. We derive boundary conditions for the two limiting cases of nearly smooth and nearly perfectly rough spheres, as a hydrodynamic description of granular gases comprising rough spheres is appropriate only in these limits. The results are illustrated by applying the equations of motion and boundary conditions to the problem of plane Couette flow.
Dynamics of a non-spherical microcapsule with incompressible interface in shear flow
Authors: VLAHOVSKA P. M. , YOUNG Y.-N. , DANKER G. , MISBAH C.
Published: April 2011

We study the motion and deformation of a liquid capsule enclosed by a surface-incompressible membrane as a model of red blood cell dynamics in shear flow. Considering a slightly ellipsoidal initial shape, an analytical solution to the creeping-flow equations is obtained as a regular perturbation expansion in the excess area. The analysis takes into account the membrane fluidity, area-incompressibility and resistance to bending. The theory captures the observed transition from tumbling to swinging as the shear rate increases and clarifies the effect of capsule deformability. Near the transition, intermittent behaviour (swinging periodically interrupted by a tumble) is found only if the capsule deforms in the shear plane and does not undergo stretching or compression along the vorticity direction; the intermittency disappears if deformation along the vorticity direction occurs, i.e. if the capsule ‘breathes’. We report the phase diagram of capsule motions as a function of viscosity ratio, non-sphericity and dimensionless shear rate.
Acoustic implications of a thin viscous boundary layer over a compliant surface or permeable liner
Authors: BRAMBLEY E. J.
Published: April 2011

This paper considers the implications of a high-Reynolds-number thin parallel boundary layer on fluid–solid interaction. Two types of boundaries are considered: a compliant boundary which is flexible but impermeable, such as an elastic sheet or elastic solid, and a permeable boundary which is rigidly fixed, such as a perforated rigid sheet. The fluid flow consists of a steady flow along the boundary and a small time-dependent perturbation, with the boundary reacting to the perturbation. The fluid displacement due to the perturbation is assumed to be much smaller than the boundary-layer thickness. The analysis is equally valid for compressible and incompressible fluids. Numerical examples are given for compressible flow along a cylindrical duct, for both permeable and compliant cylinder walls. The difference between compliant and permeable walls is shown to be dramatic in some cases. High- and low-frequency asymptotics are derived, and shown to compare well to the numerics. When used with a mass–spring–damper boundary, this model is shown to lead to similar, but not identical, temporal instability with unbounded growth rate to that seen for slipping flow using the Myers boundary condition. It is therefore suggested that a regularization of the Myers boundary condition removing the unbounded growth rate may lead to, or at least inform, a regularization of the model presented here.
Sound generation by laminar premixed flame annihilation
Authors: TALEI MOHSEN , BREAR MICHAEL J. , HAWKES EVATT R.
Published: April 2011

This paper presents a numerical and theoretical investigation of the sound generated by premixed flame annihilation. Planar, axisymmetric and spherically symmetric flame annihilation events are considered. The compressible Navier–Stokes, energy and progress variable equations are first solved using simple chemistry simulations, resolving both the flame dynamics and the acoustics. These simulations show that the amplitude of the far-field sound produced by the annihilation events depends on the flame thickness, particularly for the axisymmetric and spherically symmetric flame annihilation events. The flame propagation velocity is also always observed to increase significantly prior to flame annihilation, which is in keeping with other reported experimental and numerical studies. A theory is then presented that relates the far-field sound to the flame annihilation event by using a previously reported and extended form of Lighthill's acoustic analogy. A comparison with the numerical results shows that this theory accurately represents the far-field sound produced by considering only the temporal heat release source term in Lighthill's acoustic analogy, as reported by others. Additional assumptions of an infinitely thin flame and constant flame speed are then invoked in an attempt to simplify the problem. In the planar annihilation, this theory results in good predictions of the overall pressure change. However, these assumptions lead to significant under-prediction of the amplitude of far-field sound produced for the axisymmetric and spherically symmetric annihilation events. Finally, dimensional reasoning supported by the simulations and theory is used to develop scalings of the far-field sound in terms of the flame parameters.
Turbulence structure and interaction with steep breaking waves
Authors: LAKEHAL DJAMEL , LIOVIC PETAR
Published: April 2011

Large-eddy and interface simulation using an interface tracking-based multi-fluid flow solver is conducted to investigate the breaking of steep water waves on a beach of constant bed slope. The present investigation focuses mainly on the ‘weak plunger’ breaking wave type and provides a detailed analysis of the two-way interaction between the mean fluid flow and the sub-modal motions, encompassing wave dynamics and turbulence. The flow is analysed from two points of views: mean to sub-modal exchange, and wave to turbulence interaction within the sub-modal range. Wave growth and propagation are due to energy transfer from the mean flow to the waves, and transport of mean momentum by these waves. The vigorous downwelling–upwelling patterns developing at the head and tail of each breaker are shown to generate both negative- and positive-signed energy exchange contributions in the thin sublayer underneath the water surface. The details of these exchange mechanisms are thoroughly discussed in this paper, together with the interplay between three-dimensional small-scale breaking associated with turbulence and the dominant two-dimensional wave motion. A conditional zonal analysis is proposed for the first time to understand the transient mechanisms of turbulent kinetic energy production, decay, diffusion and transport and their dependence and/or impact on surface wrinkling over the entire breaking process. The simulations provide a thorough picture of air–liquid coherent structures that develop over the breaking process, and link them to the transient mechanisms responsible for their local incidence.
Realizing turbulent statistics
Authors: HŒPFFNER JÉRÔME , NAKA YOSHITSUGU , FUKAGATA KOJI
Published: April 2011

How to design an artificial inflow condition in simulations of the Navier–Stokes equation that is already fully turbulent? This is the turbulent inflow problem. This first question is followed by: How much of the true turbulence must be reproduced at the inflow? We present a technique able to produce a random field with the exact two-point two-time covariance of a given reference turbulent flow. It is obtained as the output of a linear filter fed with white noise. The method is illustrated on the simulation of a turbulent free shear layer. The filter coefficients are obtained from the solution of the Yule–Walker equation, and the computation can be performed efficiently using a recursive solution procedure. The method should also be useful in the study of flow receptivity, when the processes of transition to turbulence are sensitive to the perturbation environment.
Control of laminar separation using pulsed vortex generator jets: direct numerical simulations
Authors: POSTL D. , BALZER W. , FASEL H. F.
Published: April 2011

Direct numerical simulations (DNS) are employed to investigate laminar boundary layer separation and its control by pulsed vortex generator jets (VGJs), i.e. by injecting fluid into the flow through a spanwise array of small holes. Particular focus is directed towards identifying the relevant physical mechanisms associated with VGJ control of low-Reynolds-number separation, as encountered in low-pressure turbine applications. Pulsed VGJs are shown to be much more effective than steady VGJs when the same momentum coefficient is used for the actuation. From our investigations we have found that the increased control effectiveness of pulsed VGJs can be explained by the fact that linear hydrodynamic instability mechanisms are exploited. When pulsing with frequencies to which the separated shear layer is naturally unstable, instability modes are shown to develop into large-scale, spanwise coherent structures. These structures provide the necessary entrainment of high-momentum fluid to successfully reattach the flow.