bluuebunny/crossref_metadata_2025 huggingface dataset:
CREATING DATABASES FROM CROSS‐NATIONAL COMPARISONS OF FOOD MIND‐SETS
Authors: RABINO SAMUEL , MOSKOWITZ HOWARD , KATZ RACHEL , MAIER ANDREA , PAULUS KLAUS , AARTS PIETER , BECKLEY JACKIE , ASHMAN HOLLIS
Published: September 2007

This article introduces a “mind genomics” approach to gathering information on consumption attitudes toward food, and reactions to food concepts across national boundaries. Mind genomics is an approach that creates a body of knowledge as to how consumers respond to the components of a complex stimulus. Conjoint analysis has been employed to support the study where the object was to gather and evaluate information and create databases using the “mind genomics” approach. The databases contain information about product features as well as situational vignettes. The study has evaluated 22 foods and beverages in three countries, testing 20 out of the 22 food items in each country.

Our procedure looks in depth at food consumption patterns in France, the United Kingdom and Germany. Specifically, we employ direct (self‐profiling) questionnaires to capture food consumption habits for a specific food in combination with a conjoint analysis stimulus–response model to understand how consumers respond to food concepts. By combining self‐profiling and stimulus–response methods into a single interview, one can study a single food such as soup in great depth to obtain a significant understanding of consumption habits and food‐related communications factors. By conducting parallel studies with a set of many foods, one can build a clearer, more holistic picture of food habits for a single country. Then, by conducting parallel studies across countries, one can identify differences across many different dimensions. These dimensions include product features, responses to emotional statements and self‐selection of relevant criteria for food acceptance.

PRACTICAL APPLICATIONS

The results provide a strong empirical evidence that by applying the “Mind Genomic” approach across countries one can identify consumption clusters that contain self‐selection of relevant criteria for food acceptance and consumption independent of country affiliation. The study concludes with a discussion how marketing and brand managers of international companies can proactively use insights gained by analyzing linked international databases.
SENSORY CHARACTERIZATION OF VITIS VINIFERA CV. MALBEC WINES FROM SEVEN VITICULTURE REGIONS OF ARGENTINA
Authors: GOLDNER MARÍA CRISTINA , ZAMORA MARÍA CLARA
Published: September 2007

Fifty‐six Malbec wines from seven Argentine viticulture regions (Valles Calchaquíes, Mendoza del Este, Mendoza del Sur, Patagonia, Alto Río Mendoza, Valle de Uco and San Juan), of the 2004 vintage, were evaluated by sensory descriptive analysis using a panel of 10 not‐sighted assessors. “Noncommercial” samples were obtained using standardized conditions, not aging and produced with grapes corresponding to each viticulture region. Malbec wines from same regions exhibited particular characteristics. Valles Calchaquíes wines had strong herbal, spicy, sweet pepper aromas and pungency in contrast to San Juan wines that showed fruity, strawberry, honey and citrus aromas. Mendoza del Este and Valle de Uco wines were associated with cooked fruit, raisin, floral and sweetness attributes as opposed to Mendoza del Sur and Patagonia wines which were characterized by sourness, bitterness, persistency and astringency, and not by aroma attributes. Alto Río Mendoza wines were characterized by pungency, sweet pepper and bitterness.

PRACTICAL APPLICATIONS

Sensory profiling of “non‐commercial” Malbec wines developed in this research could be used as a tool to differentiate and classify Argentine Controlled Denominations of Origin (DOC). Wines with DOC have important value in the market and they are original country representative in the world. The results of this study suggest that Malbec wines from some of the regions located in latitudes 31–33° (San Juan, Mendoza del Este and Valle de Uco; Argentina) were associated with the most desired sensory characteristics. Out of these latitudes, wine‐making process would have more importance on Malbec wine quality.
What’s in a Score? Differences in Consumers’ Credit Knowledge Using OLS and Quantile Regressions
Authors: LYONS ANGELA C. , RACHLIS MITCHELL , SCHERPF ERIK
Published: September 2007

Credit literacy depends, in part, on understanding credit reports and scores. The U.S. Government Accountability Office conducted a study in 2004 to assess consumers’ knowledge of credit reports, credit scores, and the dispute resolution process. This study uses the Government Accountability Office data and estimates a series of ordinary least squares and quantile regressions to identify specific subgroups of the population that could benefit from more targeted consumer policies and financial education. The findings from this research have important implications for consumer educators, financial professionals, and policy makers, especially with respect to national strategies designed to improve consumers’ financial well‐being.
Trading Off Fish Health and Safety: Female Decision‐Making Processes toward the Risk of Methylmercury in Fish
Authors: GROBE DEANA , MANORE MELINDA M. , STILL ELIZABETH
Published: September 2007

This study takes a qualitative, point‐in‐time look at 26 females’ decision‐making processes toward trading off the risks of mercury and the health benefits of a seafood diet. The data revealed five different decision‐making processes, with 17 of the 26 participants indicating their fish consumption patterns did not change. Of the nine who changed their fish consumption in some way, six specifically reduced the amount of tuna they ate. Similarly, participants who were most at risk—women of childbearing age and those with young children—expressed fish consumption changes more frequently than others, especially in the amount of tuna they consumed.
Consumer Awareness of the Legal Obligations of Funeral Providers
Authors: KOPP STEVEN W. , KEMP ELYRIA
Published: September 2007

The results from a consumer survey that examined consumer knowledge of some parameters of the Funeral Rule are presented. Currently, all funeral home activities are regulated under the Funeral Industry Practices Rule of the Federal Trade Commission. The rule is premised on the assumption that it is difficult for consumers to make careful, informed purchase decisions in at‐need situations because of emotional stress, time pressure, and lack of familiarity with available goods and services. However, limited research has assessed how much consumers know about the legal obligations of funeral providers as provided for by the Funeral Rule. Implications for consumer protection and policy are discussed.
Gift Cards: Disclosure One Step Removed
Authors: HORNE DANIEL R.
Published: September 2007

Gift card purchases have grown significantly in recent years. The growth has been attributed to recipients being able to make personal selections that best meet their needs while reducing the giver’s risk of improper selection and wasted time. However, while gift cards have positive benefits for both giver and recipient, certain fees, and terms and conditions involved with their use and nonuse ultimately may impact the level of satisfaction derived. This paper provides background into the use of gift cards and the development of “open‐loop” and “closed‐loop” cards. Further, it examines current levels of legal protection afforded to consumers. The paper discusses how disclosure and notice, concepts intended to protect consumers, are often neglected or unusable because the actual party at risk is not the party with whom the purchase transaction was consummated. Implications are drawn for those who are charged with creating effective public policy and consumer affairs professionals who wish to provide assistance to both consumers and regulators.
Constitutional responses to extremist political associations –ETA,Batasunaand democratic norms
Authors: Cram Ian
Published: September 2007

Systems of representative democracy require that the electorate be given at regular intervals the opportunity to replace the party in government with a rival political association. In this context, the right of individuals to freedom of association permits the formation of competitor parties and prevents forms of state intervention that might otherwise privilege existing office holders and their political programmes. It follows then that restrictions on the right to political association are deserving of particularly close scrutiny. At the same time, liberal democratic constitutions usually insist that participants in electoral process manifest a level of commitment to core liberal democratic norms (such as the rule of law, toleration, the equal worth of each individual and the peaceful resolution of grievances). In the case of intolerant, extremist parties that would reject some/most of these norms, the state may invoke a range of defensive measures up to and including proscription in order to safeguard democracy. This paper takes as its focus the constitutional issues raised by the banning in Spain of Batasuna – the political wing of ETA. A legal challenge to the ban is currently before the European Court of Human Rights. Making reference to work of John Rawls, this paper considers whether the ban on Batasuna is justifiable in terms of liberal political theory, before analysing the extent to which proscription conforms to international human rights law and European Court of Human Rights jurisprudence.
High‐cell‐passage canine coronavirus vaccine providing sterilising immunity
Authors: Pratelli A.
Published: September 2007

Objectives: To evaluate the ability of a high‐cell‐passage canine coronavirus vaccine to immunise dogs against challenge with a field isolate of the virus.

Methods: Three dogs that had previously tested seronegative and virus‐negative for canine coronavirus were inoculated twice, at 21‐day intervals, with the vaccine and kept under observation. Two seronegative and virus‐negative dogs served as unvaccinated controls. For safety tests, two additional dogs were inoculated oronasally with 10 times the vaccinal dose and no reactions were observed. Faecal samples were collected daily from the vaccinated dogs after the first and second inoculations. Both vaccinated and control dogs were challenged two weeks after the second vaccination with a field canine coronavirus strain. Blood samples were collected for serological tests before vaccination and at weekly intervals after vaccinations and challenge.

Results: Virus was not detected in faecal samples after the first or second vaccinations by virus isolation assays and PCR. Significantly, the vaccinated dogs did not have clinical signs after challenge and no virus shedding was observed. The two unvaccinated control dogs had moderate enteritis, and virus was detected in cell cultures starting from three days postchallenge (dog 1) and two days postchallenge (dog 2), and by PCR for 23 median days.

Clinical Significance: This study showed the efficacy of a high‐cell‐passage canine coronavirus vaccine in preventing infection of dogs by virulent virus and, specifically, its ability to induce sterilising immunity.
FEMININITY AND ITS UNCONSCIOUS ‘SHADOWS’: GENDER AND GENERATIVE IDENTITY IN THE AGE OF BIOTECHNOLOGY
Authors: Raphael‐Leff Joan
Published: September 2007

abstract  This paper locates contemporary conceptualizations of ‘femininity’ in the context of current sociocultural changes. It is argued that today's biotechnological opportunities have immense significance for both psychic interiority and the lived experience of gender, in that they invalidate ‘eternal’ limitations of sex, procreation and embodiment. An explanatory concept, generative identity, is postulated, to account psychologically for the increasing diversity of reproductive patterns. This concept is proposed as a fourth constituent of gender, alongside the reformulated constituents of embodiment, representation and desire. Derived from this is a further concept of generative agency– the expression of the psychic construction of the self as potential pro‐creator, shaped in childhood by the negotiation of reproductive restrictions of sex, generation, genesis and generativity, and the ‘genitive’ issues of arbitrariness, finitude and irreversibility of time. Disturbances in generative identity manifest as unconscious ‘shadows’ expressed as inhibitions to creative agency, compulsively driven preoccupations with the lived sexed body, and/or concrete enactments which may utilize biotechnological innovations to actualize unconscious fantasies in reality.
NEW PSYCHOANALYTIC THEORIES OF FEMALE AND MALE FEMININITY: THE OEDIPUS COMPLEX, LANGUAGE AND GENDER EMBODIMENT
Authors: Maguire Marie , Dewing Hilary
Published: September 2007

abstract  This edited interview explores the clinical applications of recent critiques of oedipal theories of ‘femininity’. We discuss new thinking about language, sexuality and how we symbolize gender through our bodies, illustrating the influence of neuro‐psychoanalysis (Solms & Turnbull 2002) and post‐Lacanian theory (Irigaray 1977; Grosz 1994). Radical challenges to the use of ‘binary’ categories, including masculinity/femininity, are considered, and we note that dispensing with such terminology impedes discussion of gender inequality. We explore intersubjective (Benjamin 2000) and philosophical (Butler 2000) perspectives on gender as the site for enactments of trauma (Harris 2000), along with the role of unmourned loss in the creation of heterosexual femininity. Clinical examples are counterposed: contemporary theory on male ‘femininity’ and hysteria, with recent thinking about female ‘masculinity’. We conclude that we may be reaching an impasse – the end of a golden age of theorizing about sexual identity – because of the current limitations and contradictions of psychoanalytic language and theory.
VULNERABLE TO DEPRESSION
Authors: Harris Tirril
Published: September 2007

abstract  One notable aspect of femininity is the two‐fold higher rate of depression among women. This paper outlines bio‐psychosocial models of depression and draws on studies of depressive disorder directly comparing men and women. It is suggested that the finding of consistently higher rates of negative self‐evaluation among women may be linked to experiences of parental antipathy and favouritism in childhood, and that there is a continuity of adverse childhood experience between mothers and daughters, but not mothers and sons. It also discusses the implications of the feminine caring role for self‐evaluation and affect regulation. The implications for therapeutic practice are outlined.
TRANSGENERATIONAL CONFLICTS BETWEEN SISTERS
Authors: Coles Prophecy
Published: September 2007

abstract  The first half of this paper reconsiders the therapeutic work with a patient who had a troubled relationship with her older sister (Coles 1998). In particular I explore the conflictual sibling transference and the countertransference anxieties I faced. In the second half of the paper I speculate about transgenerational conflicts between sisters and suggest that the patient's conflict with her sister, and her sense of lost identity when her sister died, may be linked to her mother's relationship with an older sister. I draw on literary sources which also illustrate the impact of sibling relationships.
Tranexamic acid, blood loss and transfusion after valve replacement cardiac surgery: a randomized controlled trial of two modes of administration
Authors: MORET ENRIQUE , FLO ANNA , ESCUDERO ADRIÀ , SARIÑENA MARIA TERESA , MASSÓ EVA , MUÑOZ SUSANA , CANET JAUME
Published: September 2007

We aimed to assess the effect of two different modalities for administering similar doses of tranexamic acid on bleeding following primary elective valve replacement cardiac surgery. In a double‐blinded, prospective, placebo‐controlled design, 209 patients scheduled for aortic, mitral or combined valve replacement were randomized to three groups: one placebo and two treatment groups applying different modalities of tranexamic acid administration (bolus injection of 30 mg/kg vs. continuous infusion). Blood loss up until removal of chest tubes was the primary outcome measure; also recorded and assessed were blood products transfused, need of resternotomy and thrombogenic complications. All groups were comparable at baseline. Blood loss and excessive bleeding were greater in the placebo group than in either treatment group (P < 0.001). Trends toward transfusion differences between groups did not reach statistical significance. No differences in thromboembolic complications, morbidity or mortality were found. In valve replacement cardiac surgery, the use of either method for administering similar doses of tranexamic acid leads to a similarly significant reduction in postoperative mediastinal bleeding, although transfusion needs remained unchanged compared with the placebo group.
The starch family: are they all equal? Pharmacokinetics and pharmacodynamics of hydroxyethyl starches
Authors: JUNGHEINRICH CORNELIUS
Published: September 2007

With the third generation of hydroxyethyl starches (HES), this product group has again moved into the focus of scientific interest. The pharmacodynamic action of HES as a colloid depends on the number of oncotically active molecules but not directly on the plasma concentration, while effects on blood coagulation, especially on factor VIII and von Willebrand factor, depend on plasma concentration and in vivo molecular weight. HES with a molar substitution above 0.4 tends to accumulate in plasma after repetitive infusion. This effect is most pronounced with hetastarch (e.g. HES 670/0.75) and corresponds to the extent of tissue storage, which is significantly reduced for HES 130/0.4 compared with hetastarch and HES 200/0.5. HES 130/0.4 does not accumulate in plasma after repetitive administration, and plasma clearance of HES 130/0.4 is more than 23 times higher than that of hetastarch. This is beneficial especially in patients with preexisting renal insufficiency, as cumulative urinary excretion, even in the presence of moderate to severe non‐anuric renal failure, is higher for HES 130/0.4 than for older HES specifications when given to healthy volunteers. No adverse effects on kidney function have been observed for HES 130/0.4 compared with gelatin in patients with preoperative renal impairment undergoing aortic surgery. Based on recent study results, HES 130/0.4 may be given to patients with renal impairment as long as urine flow is preserved. The volume effect induced by HES does not directly mirror pharmacokinetics. Equivalent volume efficacy has been proven for HES 130/0.4 versus HES 200/0.5 and HES 670/0.75 despite longer intravascular persistence of the less metabolizable HES products. Influence on coagulation is minimal with HES 130/0.4. Recent clinical data showed reduced blood loss and RBC transfusion requirements when comparing HES 130/0.4 (C2/C6 > 8) with hetastarch and pentastarch. HES 130/0.4 combines the advantages of an efficacious volume therapeutic registered for high‐dose treatment with a significantly improved safety profile.
Differences in chemical structures between waxy maize‐ and potato starch‐based hydroxyethyl starch volume therapeutics
Authors: SOMMERMEYER KLAUS , CECH FRANZ , SCHOSSOW RICHARDA
Published: September 2007

Hydroxyethyl starch plasma volume expanders originating from different plant sources may have different physicochemical and clinical properties. We therefore compared the physicochemical properties of two medium‐molecular‐weight hydroxyethyl starch (HES) plasma volume expanders with a declared average molecular weight of 130 kDa and molar substitutions of 0.4 and 0.42, respectively, derived from waxy maize starch and potato starch, respectively. For HES based on waxy maize starch, we could demonstrate a higher mean degree of branching and a much lower degree of esterification with phosphoric acid, compared with the potato starch‐based product. This is in accordance with the Mark–Houwink plots of potato starch‐based HES showing higher values of the limiting viscosity over the whole molecular weight range in comparison with waxy maize starch‐based HES. The relevance of these data on pharmacological properties is discussed. Waxy maize‐ and potato starch‐based hydroxyethyl starch plasma volume expanders differ in their chemical fine structure. Their pharmacological and clinical equivalence remains to be proven with further studies.
Collagen Fiber Alignment Does Not Explain Mechanical Anisotropy in Fibroblast Populated Collagen Gels
Authors: Thomopoulos Stavros , Fomovsky Gregory M. , Chandran Preethi L. , Holmes Jeffrey W.
Published: September 2007

Many load-bearing soft tissues exhibit mechanical anisotropy. In order to understand the behavior of natural tissues and to create tissue engineered replacements, quantitative relationships must be developed between the tissue structures and their mechanical behavior. We used a novel collagen gel system to test the hypothesis that collagen fiber alignment is the primary mechanism for the mechanical anisotropy we have reported in structurally anisotropic gels. Loading constraints applied during culture were used to control the structural organization of the collagen fibers of fibroblast populated collagen gels. Gels constrained uniaxially during culture developed fiber alignment and a high degree of mechanical anisotropy, while gels constrained biaxially remained isotropic with randomly distributed collagen fibers. We hypothesized that the mechanical anisotropy that developed in these gels was due primarily to collagen fiber orientation. We tested this hypothesis using two mathematical models that incorporated measured collagen fiber orientations: a structural continuum model that assumes affine fiber kinematics and a network model that allows for nonaffine fiber kinematics. Collagen fiber mechanical properties were determined by fitting biaxial mechanical test data from isotropic collagen gels. The fiber properties of each isotropic gel were then used to predict the biaxial mechanical behavior of paired anisotropic gels. Both models accurately described the isotropic collagen gel behavior. However, the structural continuum model dramatically underestimated the level of mechanical anisotropy in aligned collagen gels despite incorporation of measured fiber orientations; when estimated remodeling-induced changes in collagen fiber length were included, the continuum model slightly overestimated mechanical anisotropy. The network model provided the closest match to experimental data from aligned collagen gels, but still did not fully explain the observed mechanics. Two different modeling approaches showed that the level of collagen fiber alignment in our uniaxially constrained gels cannot explain the high degree of mechanical anisotropy observed in these gels. Our modeling results suggest that remodeling-induced redistribution of collagen fiber lengths, nonaffine fiber kinematics, or some combination of these effects must also be considered in order to explain the dramatic mechanical anisotropy observed in this collagen gel model system.
Membrane Transport Properties of Equine and Macaque Ovarian Tissues Frozen in Mixtures of Dimethylsulfoxide and Ethylene Glycol
Authors: Kardak A. , Leibo S. P. , Devireddy R.
Published: September 2007

The rate at which equine and macaque ovarian tissue sections are first cooled from +25°Cto+4°C has a significant effect on the measured water transport when the tissues are subsequently frozen in 0.85M solutions of glycerol, dimethylsulfoxide (DMSO), or ethylene glycol (EG). To determine whether the response of ovarian tissues is altered if they are suspended in mixtures of cryoprotective agents (CPAs), rather than in solutions of a single CPA, we have now measured the subzero water transport from ovarian tissues that were suspended in mixtures of DMSO and EG. Sections of freshly collected equine and macaque ovaries were suspended either in a mixture of 0.9M EG plus 0.7M DMSO (equivalent to a mixture of ∼5%v∕v of EG and DMSO) or in a 1.6M solution of only DMSO or only EG. The tissue sections were cooled from +25°Cto+4°C and then frozen to subzero temperatures at 5°C∕min. As the tissues were being frozen, a shape-independent differential scanning calorimeter technique was used to measure water loss from the tissues and, consequently, the best fit membrane permeability parameters (Lpg and ELp) of ovarian tissues during freezing. In the mixture of DMSO+EG, the respective values of Lpg and ELp for equine tissue first cooled at 40°C∕min between +25°C and +4°C before being frozen were 0.15μm∕minatm and 7.6kcal∕mole. The corresponding Lpg and ELp values for equine tissue suspended in 1.6M DMSO were 0.12μm∕minatm and 27.2kcal∕mole; in 1.6M EG, the values were 0.06μm∕minatm and 21.9kcal∕mole, respectively. For macaque ovarian tissues suspended in the mixture of DMSO+EG, the respective values of Lpg and ELp were 0.26μm∕minatm and 26.2kcal∕mole. Similarly, the corresponding LLg and ELp values for macaque tissue suspended in 1.6M DMSO were 0.22μm∕minatm and 31.4kcal∕mole; in 1.6M EG, the values were 0.20μm∕minatm and 27.9kcal∕mole. The parameters for both equine and macaque tissue samples suspended in the DMSO+EG mixture and first cooled at 0.5°C∕min between +25°C and +4°C were very similar to the corresponding values for samples cooled at 40°C∕min. In contrast, the membrane parameters of equine and macaque samples first cooled at 0.5°C∕min in single-component solutions were significantly different from the corresponding values for samples cooled at 40°C∕min. These results show that the membrane properties of ovarian cells from two species are different, and that the membrane properties are significantly affected both by the solution in which the tissue is suspended and by the rate at which the tissue is cooled from +25°Cto+4°C before being frozen. These observations suggest that these variables ought to be considered in the derivation of methods to cryopreserve ovarian tissues.
Finite Element Modeling of the First Ray of the Foot: A Tool for the Design of Interventions
Authors: Budhabhatti Sachin P. , Erdemir Ahmet , Petre Marc , Sferra James , Donley Brian , Cavanagh Peter R.
Published: September 2007

Disorders of the first ray of the foot (defined as the hard and soft tissues of the first metatarsal, the sesamoids, and the phalanges of the great toe) are common, and therapeutic interventions to address these problems range from alterations in footwear to orthopedic surgery. Experimental verification of these procedures is often lacking, and thus, a computational modeling approach could provide a means to explore different interventional strategies. A three-dimensional finite element model of the first ray was developed for this purpose. A hexahedral mesh was constructed from magnetic resonance images of the right foot of a male subject. The soft tissue was assumed to be incompressible and hyperelastic, and the bones were modeled as rigid. Contact with friction between the foot and the floor or footwear was defined, and forces were applied to the base of the first metatarsal. Vertical force was extracted from experimental data, and a posterior force of 0.18 times the vertical force was assumed to represent loading at peak forefoot force in the late-stance phase of walking. The orientation of the model and joint configuration at that instant were obtained by minimizing the difference between model predicted and experimentally measured barefoot plantar pressures. The model were then oriented in a series of postures representative of push-off, and forces and joint moments were decreased to zero simultaneously. The pressure distribution underneath the first ray was obtained for each posture to illustrate changes under three case studies representing hallux limitus, surgical arthrodesis of the first ray, and a footwear intervention. Hallux limitus simulations showed that restriction of metatarsophalangeal joint dorsiflexion was directly related to increase and early occurrence of hallux pressures with severe immobility increasing the hallux pressures by as much as 223%. Modeling arthrodesis illustrated elevated hallux pressures when compared to barefoot and was dependent on fixation angles. One degree change in dorsiflexion and valgus fixation angles introduced approximate changes in peak hallux pressure by 95 and 22 kPa, respectively. Footwear simulations using flat insoles showed that using the given set of materials, reductions of at least 18% and 43% under metatarsal head and hallux, respectively, were possible.
Three-Dimensional Convective Alveolar Flow Induced by Rhythmic Breathing Motion of the Pulmonary Acinus
Authors: Sznitman Josué , Heimsch Fabian , Heimsch Thomas , Rusch Daniel , Rösgen Thomas
Published: September 2007

Low Reynolds number flows (Re<1) in the human pulmonary acinus are often difficult to assess due to the submillimeter dimensions and accessibility of the region. In the present computational study, we simulated three-dimensional alveolar flows in an alveolated duct at each generation of the pulmonary acinar tree using recent morphometric data. Rhythmic lung expansion and contraction motion was modeled using moving wall boundary conditions to simulate realistic sedentary tidal breathing. The resulting alveolar flow patterns are largely time independent and governed by the ratio of the alveolar to ductal flow rates, Q̇a∕Q̇d. This ratio depends uniquely on geometrical configuration such that alveolar flow patterns may be entirely determined by the location of the alveoli along the acinar tree. Although flows within alveoli travel very slowly relative to those in acinar ducts, 0.021%⩽Ua∕Ud⩽9.1%, they may exhibit complex patterns linked to the three-dimensional nature of the flow and confirm findings from earlier three-dimensional simulations. Such patterns are largely determined by the interplay between recirculation in the cavity induced by ductal shear flow over the alveolar opening and radial flows induced by wall displacement. Furthermore, alveolar flow patterns under rhythmic wall motion contrast sharply with results obtained in a rigid alveolus, further confirming the importance of including inherent wall motion to understand realistic acinar flow phenomena. The present findings may give further insight into the role of convective alveolar flows in determining aerosol kinematics and deposition in the pulmonary acinus.
Effect of Indenter Size on Elastic Modulus of Cartilage Measured by Indentation
Authors: Simha Narendra K. , Jin Hui , Hall Mellanie L. , Chiravarambath Sidharth , Lewis Jack L.
Published: September 2007

Our preliminary indentation experiments showed that the equilibrium elastic modulus of murine tibial cartilage increased with decreasing indenter size: flat-ended 60deg conical tips with end diameters of 15μm and 90μm gave 1.50±0.82MPa (mean±standard deviation) and 0.55±0.11MPa, respectively (p<0.01). The goal of this paper is to determine if the dependence on tip size is an inherent feature of the equilibrium elastic modulus of cartilage as measured by indentation. Since modulus values from nonindentation tests are not available for comparison for murine cartilage, bovine cartilage was used. Flat-ended conical or cylindrical tips with end diameters ranging from 5μmto4mm were used to measure the equilibrium elastic modulus of bovine patellar cartilage. The same tips were used to test urethane rubber for comparison. The equilibrium modulus of the bovine patellar cartilage increased monotonically with decreasing tip size. The modulus obtained from the 2mm and 4mm tips (0.63±0.21MPa) agreed with values reported in the literature; however, the modulus measured by the 90μm tip was over two and a half times larger than the value obtained from the 1000μm tip. In contrast, the elastic modulus of urethane rubber obtained using the same 5μm–4mm tips was independent of tip size. The equilibrium elastic modulus of bovine patellar cartilage measured by indentation depends on tip size. This appears to be an inherent feature of indentation of cartilage, perhaps due to its inhomogeneous structure.
On the Biaxial Mechanical Properties of the Layers of the Aortic Valve Leaflet
Authors: Stella John A. , Sacks Michael S.
Published: September 2007

All existing constitutive models for heart valve leaflet tissues either assume a uniform transmural stress distribution or utilize a membrane tension formulation. Both approaches ignore layer specific mechanical contributions and the implicit nonuniformity of the transmural stress distribution. To begin to address these limitations, we conducted novel studies to quantify the biaxial mechanical behavior of the two structurally distinct, load bearing aortic valve (AV) leaflet layers: the fibrosa and ventricularis. Strip biaxial tests, with extremely sensitive force sensing capabilities, were further utilized to determine the mechanical behavior of the separated ventricularis layer at very low stress levels. Results indicated that both layers exhibited very different nonlinear, highly anisotropic mechanical behaviors. While the leaflet tissue mechanical response was dominated by the fibrosa layer, the ventricularis contributed double the amount of the fibrosa to the total radial tension and experienced four times the stress level. The strip biaxial test results further indicated that the ventricularis exhibited substantial anisotropic mechanical properties at very low stress levels. This result suggested that for all strain levels, the ventricularis layer is dominated by circumferentially oriented collagen fibers, and the initial loading phase of this layer cannot be modeled as an isotropic material. Histological-based thickness measurements indicated that the fibrosa and ventricularis constitute 41% and 29% of the total layer thickness, respectively. Moreover, the extensive network of interlayer connections and identical strains under biaxial loading in the intact state suggests that these layers are tightly bonded. In addition to advancing our knowledge of the subtle but important mechanical properties of the AV leaflet, this study provided a comprehensive database required for the development of a true 3D stress constitutive model for the native AV leaflet.
Influence of the 3D Inverse Dynamic Method on the Joint Forces and Moments During Gait
Authors: Dumas R. , Nicol E. , Chèze L.
Published: September 2007

The joint forces and moments are commonly used in gait analysis. They can be computed by four different 3D inverse dynamic methods proposed in the literature, either based on vectors and Euler angles, wrenches and quaternions, homogeneous matrices, or generalized coordinates and forces. In order to analyze the influence of the inverse dynamic method, the joint forces and moments were computed during gait on nine healthy subjects. A ratio was computed between the relative dispersions (due to the method) and the absolute amplitudes of the gait curves. The influence of the inverse dynamic method was negligible at the ankle (2%) but major at the knee and the hip joints (40%). This influence seems to be due to the dynamic computation rather than the kinematic computation. Compared to the influence of the joint center location, the body segment inertial parameter estimation, and more, the influence of the inverse dynamic method is at least of equivalent importance. This point should be confirmed with other subjects, possibly pathologic, and other movements.
Numerical Characterization of Diffusion-Based Extraction in Cell-Laden Flow Through a Microfluidic Channel
Authors: Fleming K. K. , Longmire E. K. , Hubel A.
Published: September 2007

Cells are routinely cryopreserved in dimethyl sulfoxide (DMSO), a cryoprotective agent, for medical applications. Infusion of a DMSO-laden cell suspension results in adverse patient reactions, but current DMSO extraction processes result in significant cell losses. A diffusion-based numerical model was employed to characterize DMSO extraction in fully developed channel flow containing a wash stream flowing parallel to a DMSO-laden cell suspension. DMSO was allowed to diffuse across cell membranes as well as across the channel depth. A variety of cases were considered with the ultimate goal of characterizing the optimal geometry and flow conditions to process clinical volumes of cell suspension in a reasonable time (2–3ml∕min). The results were dependent on four dimensionless parameters: depth fraction of the DMSO-laden stream, Peclet number, cell volume fraction in the DMSO-laden stream, and cell membrane permeability parameter. Smaller depth fractions led to faster DMSO extraction but channel widths that were not practical. Higher Peclet numbers led to longer channels but smaller widths. For the Peclet values and channel depths considered (⩾500μm) and appropriate permeability values, diffusion across cell membranes was significantly faster than diffusion across the channel depth. Cell volume fraction influenced the cross-stream diffusion of DMSO by limiting the fluid volume fraction available in the contaminant stream but did not play a significant role in channel geometry or operating requirements. The model was validated against preliminary experiments in which DMSO was extracted from suspensions of B-lymphoblast cells. The model results suggest that a channel device with practical dimensions can remove a sufficient level of contaminant within a mesoscale volume of cells in the required time.
Secondary Velocity Fields in the Conducting Airways of the Human Lung
Authors: Fresconi Frank E. , Prasad Ajay K.
Published: September 2007

An understanding of flow and dispersion in the human respiratory airways is necessary to assess the toxicological impact of inhaled particulate matter as well as to optimize the design of inhalable pharmaceutical aerosols and their delivery systems. Secondary flows affect dispersion in the lung by mixing solute in the lumen cross section. The goal of this study is to measure and interpret these secondary velocity fields using in vitro lung models. Particle image velocimetry experiments were conducted in a three-generational, anatomically accurate model of the conducting region of the lung. Inspiration and expiration flows were examined under steady and oscillatory flow conditions. Results illustrate secondary flow fields as a function of flow direction, Reynolds number, axial location with respect to the bifurcation junction, generation, branch, phase in the oscillatory cycle, and Womersley number. Critical Dean number for the formation of secondary vortices in the airways, as well as the strength and development length of secondary flow, is characterized. The normalized secondary velocity magnitude was similar on inspiration and expiration and did not vary appreciably with generation or branch. Oscillatory flow fields were not significantly different from corresponding steady flow fields up to a Womersley number of 1 and no instabilities related to shear were detected on flow reversal. These observations were qualitatively interpreted with respect to the simple streaming, augmented dispersion, and steady streaming convective dispersion mechanisms.
Mixing and Modes of Mass Transfer in the Third Cerebral Ventricle: A Computational Analysis
Authors: Kurtcuoglu Vartan , Soellinger Michaela , Summers Paul , Poulikakos Dimos , Boesiger Peter
Published: September 2007

Anatomic, velocimetric, and brain motion MRI scans were combined with a computational fluid dynamics model to investigate cerebrospinal fluid (CSF) mixing in the third cerebral ventricle of a healthy male adult. It was found that advection dominates over diffusion in most of the third ventricle. Three zones where diffusion plays an important role in the mixing process were identified. One of these zones, consisting of recessus infundibulus, recessus opticus and the adjacent regions up to commissura anterior, is likely to exist in the general population. We hypothesize that this zone may act as a buffer to flatten concentration peaks of pituitary gland hormones released into the CSF of the third ventricle. We further hypothesize that this zone may facilitate the communication between hypothalamus and the pituitary gland through the third ventricle cerebrospinal fluid by prolonging residence times of the communicated hormones.
Hyperelastic Anisotropic Microplane Constitutive Model for Annulus Fibrosus
Authors: Caner Ferhun C. , Guo Zaoyang , Moran Brian , Bažant Zdeněk P. , Carol Ignacio
Published: September 2007

In a recent paper, Peng et al. (2006, “An Anisotropic Hyperelastic Constitutive Model With Fiber-Matrix Interaction for the Human Annulus Fibrosis,” ASME J. Appl. Mech., 73(5), pp. 815–824) developed an anisotropic hyperelastic constitutive model for the human annulus fibrosus in which fiber-matrix interaction plays a crucial role in simulating experimental observations reported in the literature. Later, Guo et al. (2006, “A Composites-Based Hyperelastic Constitutive Model for Soft Tissue With Application to the Human Fibrosis,” J. Mech. Phys. Solids, 54(9), pp. 1952–1971) used fiber reinforced continuum mechanics theory to formulate a model in which the fiber-matrix interaction was simulated using only composite effect. It was shown in these studies that the classical anisotropic hyperelastic constitutive models for soft tissue, which do not account for this shear interaction, cannot accurately simulate the test data on human annulus fibrosus. In this study, we show that the microplane model for soft tissue developed by Caner and Carol (2006, “Microplane Constitutive Model and Computational Framework for Blood Vessel Tissue,” ASME J. Biomech. Eng., 128(3), pp. 419–427) can be adjusted for human annulus fibrosus and the resulting model can accurately simulate the experimental observations without explicit fiber-matrix interaction because, in microplane model, the shear interaction between the individual fibers distributed in the tissue provides the required additional rigidity to explain these experimental facts. The intensity of the shear interaction between the fibers can be adjusted by adjusting the spread in the distribution while keeping the total amount of the fiber constant. A comparison of results obtained from (i) a fiber-matrix parallel coupling model, which does not account for the fiber-matrix interaction, (ii) the same model but enriched with fiber-matrix interaction, and (iii) microplane model for soft tissue adapted to annulus fibrosus with two families of fiber distributions is presented. The conclusions are (i) that varying degrees of fiber-fiber and fiber-matrix shear interaction must be taking place in the human annulus fibrosus, (ii) that this shear interaction is essential to be able to explain the mechanical behavior of human annulus fibrosus, and (iii) that microplane model can be fortified with fiber-matrix interaction in a straightforward manner provided that there are new experimental data on distribution of fibers, which indicate a spread so small that it requires an explicit fiber-matrix interaction to be able to simulate the experimental data.
Local Temperature Rises Influence In Vivo Electroporation Pore Development: A Numerical Stratum Corneum Lipid Phase Transition Model
Authors: Becker S. M. , Kuznetsov A. V.
Published: September 2007

Electroporation is an approach used to enhance transdermal transport of large molecules in which the skin is exposed to a series of electric pulses. Electroporation temporarily destabilizes the structure of the outer skin layer, the stratum corneum, by creating microscopic pores through which agents, ordinarily unable to pass into the skin, are able to pass through this outer barrier. Long duration electroporation pulses can cause localized temperature rises, which result in thermotropic phase transitions within the lipid bilayer matrix of the stratum corneum. This paper focuses on electroporation pore development resulting from localized Joule heating. This study presents a theoretical model of electroporation, which incorporates stratum corneum lipid melting with electrical and thermal energy equations. A transient finite volume model is developed representing electroporation of in vivo human skin, in which stratum corneum lipid phase transitions are modeled as a series of melting processes. The results confirm that applied voltage to the skin results in high current densities within the less resistive regions of the stratum corneum. The model captures highly localized Joule heating within the stratum corneum and subsequent temperature rises, which propagate radially outward. Electroporation pore development resulting from the decrease in resistance associated with lipid melting is captured by the lipid phase transition model. As the effective pore radius grows, current density and subsequent Joule heating values decrease.
Effects of Diffusion Coefficients and Struts Apposition Using Numerical Simulations for Drug Eluting Coronary Stents
Authors: Mongrain Rosaire , Faik Isam , Leask Richard L. , Rodés-Cabau Josep , Larose Éric , Bertrand Olivier F.
Published: September 2007

In the context of drug eluting stent, we present two-dimensional numerical models of mass transport of the drug in the wall and in the lumen to study the effect of the drug diffusion coefficients in the three principal media (blood, vascular wall, and polymer coating treated as a three-compartment problem) and the impact of different strut apposition configurations (fully embedded, half embedded, and not embedded). The different conditions were analyzed in terms of their consequence on the drug concentration distribution in the arterial wall. We apply the concept of the therapeutic window to the targeted vascular wall region and derive simple metrics to assess the efficiency of the various stent configurations. Although most of the drug is dispersed in the lumen, variations in the blood flow rate within the physiological range of coronary blood flow and the diffusivity of the drug molecule in the blood were shown to have a negligible effect on the amount of drug in the wall. Our results reveal that the amount of drug cumulated in the wall depends essentially on the relative values of the diffusion coefficients in the polymer coating and in the wall. Concerning the strut apposition, it is shown that the fully embedded strut configuration would provide a better concentration distribution.
Finite Element and Experimental Cortex Strains of the Intact and Implanted Tibia
Authors: Completo A. , Fonseca F. , Simões J. A.
Published: September 2007

Finite Element (FE) models for the simulation of intact and implanted bone find their main purpose in accurately reproducing the associated mechanical behavior. FE models can be used for preclinical testing of joint replacement implants, where some biomechanical aspects are difficult, if not possible, to simulate and investigate in vitro. To predict mechanical failure or damage, the models should accurately predict stresses and strains. Commercially available synthetic femur models have been extensively used to validate finite element models, but despite the vast literature available on the characteristics of synthetic tibia, numerical and experimental validation of the intact and implant assemblies of tibia are very limited or lacking. In the current study, four FE models of synthetic tibia, intact and reconstructed, were compared against experimental bone strain data, and an overall agreement within 10% between experimental and FE strains was obtained. Finite element and experimental (strain gauge) models of intact and implanted synthetic tibia were validated based on the comparison of cortex bone strains. The study also includes the analysis carried out on standard tibial components with cemented and noncemented stems of the P.F.C Sigma Modular Knee System. The overall agreement within 10% previously established was achieved, indicating that FE models could be successfully validated. The obtained results include a statistical analysis where the root-mean-square-error values were always <10%. FE models can successfully reproduce bone strains under most relevant acting loads upon the condylar surface of the tibia. Moreover, FE models, once properly validated, can be used for preclinical testing of tibial knee replacement, including misalignment of the implants in the proximal tibia after surgery, simulation of long-term failure according to the damage accumulation failure scenario, and other related biomechanical aspects.