bluuebunny/crossref_metadata_2025 huggingface dataset:
What is Waste that We Should Account for it? A Look Inside Queensland's Ecological Rucksack
Authors: KNIGHT LAURENCE
Published: June 2009

While most Australians are conscious of the amount of waste that they place in garbage bins, relatively few would be aware of the waste that is generated in the course of producing the goods and services that they consume. This ‘embodied waste’ makes up a large part of the ‘ecological rucksack’ of those goods and services.

This study develops a waste account for Queensland, using the ecological rucksack framework to illustrate patterns of waste production in the Australian economy. It classifies wastes both by type and broad sector of production.

The study finds that the Queensland economy generated more than four billion tonnes of waste during the 2006–2007 financial year. The largest waste streams are produced at the resource extraction and distribution stages, and are predominantly materials that are disposed of without being used or are lost through inefficient use. The majority of the waste is produced upstream of the point of consumption and a large part is associated with materials produced for export.
The Evolution of Peat‐Swamp Channels and Organic Floodplains, Barrington Tops, New South Wales, Australia
Authors: NANSON R.A.
Published: June 2009

Geomorphology, geochronology and palynology are used to assess the development and stability of two channelled swamps on the Barrington Tops plateau. While both swamps commenced peat accumulation prior to about 4000 cal BP, new stratigraphic data indicate incision between 700 and 1000 cal BP, in response to regional climate change. Two broad stratigraphic units are identified in each swamp: the upper floodplain, comprised entirely of peat, and the inset floodplain, underlain by interbedded peat and fluvial sediments. Following incision, rapid vertical growth of the inset floodplain occurred on the Barrington River between 690 and 620 cal BP, and palynological data indicate a change from more saturated pre‐incision swamp flora to less saturated post‐incision swamp flora. Bankfull stage‐height, achieved many times in a year, is remarkably consistent along the length of each swamp channel. Its elevation controls the overall elevation of the swamps by controlling the height of the water‐table and hence the growth of swamp vegetation and formation of peat. In particular, contemporary channel dimensions control the growth and height of the inset floodplain, a process that results in the formation of an organic floodplain not previously described in the geomorphic literature.
International ranking of law journals – can it be done and at what cost?
Authors: Svantesson Dan Jerker B.
Published: June 2009

This paper discusses issues associated with international ranking of law journals. Some catalysts for the development of international journal ranking are highlighted, reasons for ranking are discussed and a range of ranking methodologies are analysed. The paper illustrates the problems associated with international journal rankings and the negative consequences that inevitably flow from such exercises.

The paper was prompted by the Australian Research Council's (ARC)'s recent Excellence in Research for Australia (ERA) scheme which, as one of its components, requires international journal ranking. While examples are drawn from the ERA scheme, the paper's discussion is general and much broader in scope. That is because schemes like the ERA will come and go, but the issues of international journal rankings will remain.
Transferred malice in tort law?
Authors: Beever Allan
Published: June 2009

Should the doctrine of transferred malice operate in the law of tort? Although there has been little written on this topic in England and Wales, it appears generally to have been accepted by academic commentators that the answer to this question is in the affirmative. Consequently, when the High Court in Bici v Ministry of Defence applied the doctrine to the tort of battery, most regarded this as unremarkable. This paper, however, argues that this position is mistaken: that the doctrine of transferred malice has, and can have, no place in the law of tort. The paper also examines the nature of intention operative in the law of trespass and its relationship with recklessness.
Facilitating best practice in aged care: exploring influential factors through critical incident technique
Authors: Janes Nadine , Fox Mary , Lowe Mandy , McGilton Kathy , Schindel‐Martin Lori
Published: June 2009

Aim.  The focus of this study is on the perspective of facilitators of evidence‐based aged care in long‐term care (LTC) homes about the factors that influence the outcome of their efforts to encourage nursing staff use of best practice knowledge.

Design.  Critical incident technique was used to examine facilitators’ experiences.

Methods.  Thirty‐four participants submitted critical incident stories about their facilitation experiences through face‐to‐face interviews, telephone interviews, and/or a web‐based written questionnaire. The resultant 123 stories were analysed using an inductive qualitative approach.

Results.  Factors at individual and contextual levels impacted the success of facilitators’ work. The approaches and traits of facilitators as well as the emotionality and intellectual capacity of nursing staff were the individual factors of influence. On a contextual level, the inherent leadership, culture, and workload demands within LTC homes, as well as externally imposed standards were influential.

Conclusions.  Primary factors influencing the facilitation of best aged care in LTC homes appear to be largely relational in nature and intimately connected to the emotionality of those who work within these settings. Enhancing the interactional patterns amongst staff and leaders as well as promoting a positive emotional climate may be particularly effective in promoting better aged care nursing practice.
Validated RealTime reverse transcriptase PCR methods for the diagnosis and pathotyping of Eurasian H7 avian influenza viruses
Authors: Slomka Marek J. , Pavlidis Theo , Coward Vivien J. , Voermans John , Koch Guus , Hanna Amanda , Banks Jill , Brown Ian H.
Published: June 2009

Background  Avian influenza (AI) caused by H7 AI viruses (AIVs) of both low pathogenicity (LP) and high pathogenicity (HP) are notifiable poultry diseases.

Objectives  Design and validate two RealTime reverse transcriptase polymerase chain reactions (RRT PCRs) for Eurasian H7 AIV detection and pathotyping.

Methods  The H7 RRT PCRs amplified within the (i) HA2 and (ii) cleavage site CS regions of the haemagglutinin gene. Both were validated against 65 H7 AIVs, 57 non‐H7 AIVs and 259 poultry swabs in comparison to M gene (AI generic) RRT PCR and virus isolation (VI). An additional 38 swabs and 20 tissue specimens extended validation against M gene RRT PCR.

Results  Both H7 RRT PCRs amplified all 61 Eurasian lineage H7 AIVs and none of 57 non‐H7 AIVs. A total of 297 poultry swabs were used to determine diagnostic sensitivity and specificity relative to M gene RRT PCR, sensitivity was 95·4% and 64·6% for the HA2 and CS RRT PCRs respectively, and specificity 97·9% and 99·6% respectively. The H7 HA2 RRT PCR was more sensitive than VI. This was emphasized by analysis of 37 swabs from turkeys infected experimentally with HPAI H7N1 virus sampled at 24 hours post‐inoculation and LPAI H7N1 chicken infections sampled at 40–64 hours. Although less sensitive, usefulness of the H7 CS RRT PCR was confirmed by the correct molecular pathotyping for all 61 Eurasian lineage H7 AIVs tested.

Conclusions  The high sensitivity of H7 HA2 RRT PCR confirms its suitability for use in poultry surveillance and disease diagnosis. H7 CS RRT PCR provides an opportunity for rapid pathotyping of H7 AIVs.
Understanding influenza transmission, immunity and pandemic threats
Authors: Mathews John D. , Chesson Joanne M. , McCaw James M. , McVernon Jodie
Published: June 2009

Abstract The current pandemic threat can be best understood within an ecological framework that takes account of the history of past pandemics caused by influenza A, the relationships between pandemic and seasonal spread of influenza viruses, and the importance of immunity and behavioural responses in human populations. Isolated populations without recent exposure to seasonal influenza seem more susceptible to new pandemic viruses, and much collateral evidence suggests that this is due to immunity directed against epitopes shared between pandemic and previously circulating strains of inter‐pandemic influenza A virus. In the highly connected modern world, most populations are regularly exposed to non‐pandemic viruses, which can even boost immunity without causing influenza symptoms. Such naturally‐induced immunity helps to explain the low attack‐rates of seasonal influenza, as well as the moderate attack‐rates in many urbanized populations affected by 1918–1919 and later pandemics. The effectiveness of immunity, even against seasonal influenza, diminishes over time because of antigenic drift in circulating viruses and waning of post‐exposure immune responses. Epidemiological evidence suggests that cross‐protection against a new pandemic strain could fade even faster. Nevertheless, partial protection, even of short duration, induced by prior seasonal influenza or vaccination against it, could provide important protection in the early stages of a new pandemic.
Association Between Lifetime Cigarette Smoking and Lewy Body Accumulation
Authors: Tsuang Debby , Larson Eric B. , Li Ge , Shofer Jane B. , Montine Kathleen S. , Thompson Mary Lou , Sonnen Joshua A. , Crane Paul K. , Leverenz James B. , Montine Thomas J.
Published: June 2009

Cigarette smoking has been associated repeatedly in observational studies with decreased risk of Parkinson's disease (PD), but its relationship to the risk of dementia or Alzheimer's disease (AD) is inconsistent. All of these studies have used clinical diagnoses of disease. We tested the hypothesis that lifetime cigarette use might be associated with reduced risk of neuropathologic changes of Lewy‐related pathology (LRP) in multiple brain regions or with reduced risk of consensus neuropathologic changes of AD in a prospective community‐based study of brain aging and dementia, the Adult Changes in Thought (ACT) study. We observed that heavy lifetime cigarette smoking (>50 pack years) was associated with significantly reduced relative risk (RR) for LRP, but not AD‐type pathologic changes, after correcting for selection bias, and with significantly reduced frequency of LRP in the substantia nigra. These findings are the first of which we are aware to associate reduced LRP in human brain with any exposure, and substantiate observational studies that have associated cigarette smoking with reduced risk of PD. Although cigarette smoking is too toxic to suggest as a treatment, if confirmed, these findings may guide future therapeutic strategies that attempt to suppress LRP in human brain by other means.
Procyanidin Content of Grape Seed and Pomace, and Total Anthocyanin Content of Grape Pomace as Affected by Extrusion Processing
Authors: Khanal R.C. , Howard L.R. , Prior R.L.
Published: June 2009

ABSTRACT:  Grape juice processing by‐products, grape seed and pomace are a rich source of procyanidins, compounds that may afford protection against chronic disease. This study was undertaken to identify optimal extrusion conditions to enhance the contents of monomers and dimers at the expense of large molecular weight procyanidin oligomers and polymers in grape seed and pomace. Extrusion variables, temperature (160, 170, and 180 °C in grape seed, and 160, 170, 180, and 190 °C in pomace) and screw speed (100, 150, and 200 rpm in both) were tested using mixtures of grape seed as well as pomace with decorticated white sorghum flour at a ratio of 30 : 70 and moisture content of 45%. Samples of grape seed and pomace were analyzed for procyanidin composition before and after extrusion, and total anthocyanins were determined in pomace. Additionally, chromatograms from diol and normal phase high‐performance liquid chromatography were compared for the separation of procyanidins. Extrusion of both grape by‐products increased the biologically important monomer and dimers considerably across all temperature and screw speeds. Highest monomer content resulted when extruded at a temperature of 170 °C and screw speed of 200 rpm, which were 120% and 80% higher than the unextruded grape seed and pomace, respectively. Increases in monomer and dimer contents were apparently the result of reduced polymer contents, which declined by 27% to 54%, or enhanced extraction facilitated by disruption of the food matrix during extrusion. Extrusion processing reduced total anthocyanins in pomace by 18% to 53%.

Practical Applications: Extrusion processing can be used to increase procyanidin monomer and dimer contents in grape seed and pomace. Procyanidins in grape by‐products have many health benefits, but most are present as large molecular weight compounds, which are poorly absorbed. Extrusion processing appears to be a promising technology to increase levels of the bioactive low molecular weight procyanidins.
Effect of Maturity Stages and Drying Methods on the Retention of Selected Nutrients and Phytochemicals in Bitter Melon (Momordica charantia) Leaf
Authors: Zhang Min , Hettiarachchy Navam S. , Horax Ronny , Chen Pengyin , Over Kenneth F.
Published: June 2009

ABSTRACT:  The purpose of this study was to investigate the nutrient and phytochemical composition of bitter melon leaves under varying maturity levels and drying techniques. Fresh, oven‐dried, and freeze‐dried leaves were evaluated over 3 maturity stages. In fresh leaves at various stages, crude fat, crude protein, and soluble dietary fiber contents ranged from 4.2% to 13.6%, 6.4% to 23.1%, and 0.04% to 3.50% on dry‐weight basis, respectively. The contents of K, Ca, Mg, Fe, and Zn ranged from 1850.8 to 2811.8, 837.4 to 4978.2, 317.3 to 512.4, 8.4 to 16.7, and 4.1 to 5.9 mg/100 g dry‐weight basis, respectively. Vitamin C, β‐carotene, and lutein contents ranged from 397.4 to 1275.1, 154.2 to 422.8, and 737.6 to 1304.6 μg/g dry‐weight basis. The major flavonoids and phenolic acids were rutin, gentistic acid, and o‐coumaric acid, which ranged from 7.57 to 12.75, 2.53 to 10.11, and 4.24 to 9.75 mg/g dry‐weight basis, respectively. In oven‐dried samples, 40.2% to 52.3% of vitamin C, 35.4% to 55.4% of β‐carotene, 25.6% to 71.6% of lutein, 26.4% to 84.0% of rutin, trace to 11.4% of gentistic acid, and 7.4% to 46.6% of o‐coumaric acid were retained, while the retainment ratios of these components in freeze‐dried samples were 84.7% to 99.0%, 76.4% to 99.3%, 90.4% to 96.1%, 39.8% to 99.3%, 24.1% to 68.4%, and 75.8% to 87.0%, respectively. The data showed that freeze‐drying better preserves the nutrient and phytochemical quality of bitter melon leaves in comparison to oven‐drying. Bitter melon leaf is a rich source of selected nutrients and phytochemicals.
Essential Oil of Aegle marmelos as a Safe Plant‐Based Antimicrobial Against Postharvest Microbial Infestations and Aflatoxin Contamination of Food Commodities
Authors: Singh Priyanka , Kumar Ashok , Dubey Nawal K. , Gupta Rajesh
Published: June 2009

ABSTRACT:  The essential oil of Aegle marmelos L. Correa (Rutaceae) showed strong fungitoxicity against some storage fungi‐causing contamination of foodstuffs. The oil also showed efficacy as aflatoxin suppressor at 500 μL/L as it completely arrested the aflatoxin B1 production by the toxigenic strains (Navjot 4NSt and Saktiman 3NSt) of Aspergillus flavus Link. Keeping in view the side effects of synthetic fungicides, A. marmelos oil may be recommended as an antimicrobial of plant origin to enhance the shelf life of stored food commodities by controlling the fungal growth as well as aflatoxin secretion. This is the 1st report on aflatoxin B1 inhibitory nature of this oil. A. marmelos oil may be recommended as a novel plant‐based antimicrobial in food protection over synthetic preservatives, most of which are reported to incite environmental problems because of their nonbiodegradable nature and side effects on mammals. The LD50 of Aegle oil was found to be 23659.93 mg/kg body weight in mice (Mus musculus L.) when administered for acute oral toxicity showing nonmammalian toxicity of the oil. GC‐MS analysis of the oil found DL‐Limonene to be major component.
Using taxonomic revision data to estimate the geographic and taxonomic distribution of undescribed species richness in the Braconidae (Hymenoptera: Ichneumonoidea)
Authors: JONES OWEN R. , PURVIS ANDY , BAUMGART ELIGIUSZ , QUICKE DONALD L.J.
Published: June 2009

Abstract.  1. Knowledge of global diversity patterns is important for research into the factors that shape them, and for systematic conservation planning. However, most species inventories are incomplete and biased towards conspicuous, charismatic, geographically widespread, and temperate species. These biases hamper attempts to gain a clear view of underlying diversity patterns, and compromise conservation plans that are based upon what is known.

2. Here we investigate this problem using two methods to estimate species diversity in the parasitic wasp family Braconidae. The first quantifies the effect of taxonomic revisions on species numbers within genera to estimate the present level of underdescription. The second additionally considers the numbers of specimens referred to in descriptions and revisions.

3. Modelling underdescription as a function of region and body size shows that research carried out thus far displays significant geographical and taxonomic biases.

4. Correcting for these biases affects the distribution of inferred undiscovered diversity among braconid subfamilies and among regions, as well as the total diversity estimates for the family.

5. The geographic distribution of levels of underdescription also has implications for latitudinal diversity gradients. Weak or non‐existent gradients in some taxa may be caused simply by differences in the number of undescribed species between tropical and temperate regions.

6. Such analyses can enlighten researchers as to where, taxonomically and geographically, research should be directed to economically improve species richness estimates. In the case of braconid wasps the greatest gains are to be made in Africa and southern America, and for the Braconinae and Microgastrinae.
Pericarp structure of the Caryopteris group (Lamiaceae subfam. Ajugoideae)
Authors: Ryding Olof
Published: June 2009

Pericarp and seed structure was investigated in 13 out of the 16 species of the old Caryopteris s.l. and in a few species of the related Rubiteucris, Amethystea, Trichostema and Ajuga. The pericarp structure was found to be very variable, and the variation largely matches the most recent classification where Caryopteris s.l. is divided into six genera: Caryopteris s.s., Discretitheca, Pseudocaryopteris, Rubiteucris, Schnabelia and Tripora. All the six genera but Rubiteucris and Schnabelia can be distinguished from each other by differences in pericarp structure, and Caryopteris s.s. was found to have a particularly divergent structure. Similarities in pericarp structure also suggest that Schnabelia, Rubiteucris and Tripora may be closely related.
Anatomy and ontogeny of unisexual flowers in dioecious Woonyoungia septentrionalis (Dandy) Law (Magnoliaceae)
Authors: FU Lin , ZENG Qing‐Wen , LIAO Jing‐Ping , XU Feng‐Xia
Published: June 2009

Abstract  Woonyoungia septentrionalis (Dandy) Law is a dioecious species with unisexual flowers in Magnoliaceae. The floral morphology and structure of the species are conspicuously different from other species and are important to the study of floral phylogeny in this family. The floral anatomy and ontogeny were investigated to evaluate the systematic position of W. septentrionalis, using scanning electron microscopy and light microscopy. All of the floral organs are initiated acropetally and spirally. The carpels are of conduplicated type without the differentiation of stigma and style. The degenerated stamens in the female flowers have the same structures as the normal stamens at the earlier developmental stages, but they do not undergo successive development and eventually degenerate. The male floral apex was observed to have the remnants of carpels in a few investigated samples. As the bisexual flower features could be traced both in the male and female flowers in W. septentrionalis, it suggests that the flower sex in Magnoliaceae tends toward unisexual. As well as the unisexual flowers, the reduced tepals and carpels and concrescence of carpels conform to the specialized tendency in Magnoliaceae, which confirms the derived position of W. septentrionalis in this family. As the initiation pattern of floral parts of W. septentrionalis is very similar to other species in this family, it needs further investigation and especially comparison with species in Kmeria to evaluate the separation of Woonyoungia.
Central nervous system regeneration: from leech to opossum
Authors: Mladinic M. , Muller K. J. , Nicholls J. G.
Published: June 2009

A major problem of neurobiology concerns the failure of injured mammalian spinal cord to repair itself. This review summarizes work done on two preparations in which regeneration can occur: the central nervous system of an invertebrate, the leech, and the spinal cord of an immature mammal, the opossum. The aim is to understand cellular and molecular mechanisms that promote and prevent regeneration. In the leech, an individual axon regrows successfully to re‐establish connections with its synaptic target, while avoiding other neurons. Functions that were lost are thereby restored. Moreover, pairs of identified neurons become re‐connected with appropriate synapses in culture. It has been shown that microglial cells and nitric oxide play key roles in leech CNS regeneration. In the opossum, the neonatal brain and spinal cord are so tiny that they survive well in culture. Fibres grow across spinal cord lesions in neonatal animals and in vitro, but axon regeneration stops abruptly between postnatal days 9 and 12. A comprehensive search has been made in spinal cords that can and cannot regenerate to identify genes and establish their locations. At 9 days, growth‐promoting genes, their receptors and key transcription molecules are up‐regulated. By contrast at 12 days, growth‐inhibitory molecules associated with myelin are prominent. The complete sequence of the opossum genome and new methods for transfecting genes offer ways to determine which molecules promote and which inhibit spinal cord regeneration. These results lead to questions about how basic research on mechanisms of regeneration could be ‘translated’ into effective therapies for patients with spinal cord injuries.
Recounting the impact of Hubel and Wiesel
Authors: Wurtz Robert H.
Published: June 2009

David Hubel and Torsten Wiesel provided a quantum step in our understanding of the visual system. In this commemoration of the 50th year of their initial publication, I would like to examine two aspects of the impact of their work. First, from the viewpoint of those interested in the relation of brain to behaviour, I recount why their initial experiments produced such an immediate impact. Hubel and Wiesel's work appeared against a background of substantial behavioural knowledge about visual perception, a growing desire to know the underlying brain mechanisms for this perception, and an abysmal lack of physiological information about the neurons in visual cortex that might underlie these mechanisms. Their initial results showed both the transformations that occur from one level of processing to the next and how a sequence of these transformations might lead to at least the elements of pattern perception. Their experiments immediately provided a structure for conceptualizing how cortical neurons could be organized to produce perception. A second impact of Hubel and Wiesel's work has been the multiple paths of research they blazed. I comment here on just one of these paths, the analysis of visual cortex in the monkey, particularly in the awake monkey. This direction has led to an explosion in the number of investigations of cortical areas beyond striate cortex and has addressed more complex behavioural questions, but it has evolved from the approach to neuronal processing pioneered by Hubel and Wiesel.
Whither the hypercolumn?
Authors: Ts'o Daniel Y. , Zarella Mark , Burkitt Guy
Published: June 2009

Among the crowning achievements of Hubel and Wiesel's highly influential studies on primary visual cortex is the description of the cortical hypercolumn, a set of cortical columns with functional properties spanning a particular parameter space. This fundamental concept laid the groundwork for the notion of a modular sensory cortex, canonical cortical circuits and an understanding of visual field coverage beyond simple retinotopy. Surprisingly, the search for and description of analogous hypercolumnar organizations in other cortical areas to date has been limited. In the present work, we have applied the hypercolumn concept to the functional organization of the second visual area, V2. We found it important to separate out the original definition of the hypercolumn from other associated observations and concepts, not all of which are applicable to V2. We present results indicating that, as in V1, the V2 hypercolumns for orientation and binocular interaction (disparity) run roughly orthogonal to each other. We quantified the ‘nearest neighbour’ periodicities for the hypercolumns for ocular dominance, orientation, colour and disparity, and found a marked similarity in the periodicities of all of these hypercolumns, both across hypercolumn type and across visual areas V1 and V2. The results support an underlying common mechanism that constrains the anatomical extent of hypercolumn systems, and highlight the original definition of the cortical hypercolumn.
Perceptual learning and adult cortical plasticity
Authors: Gilbert Charles D. , Li Wu , Piech Valentin
Published: June 2009

The visual cortex retains the capacity for experience‐dependent changes, or plasticity, of cortical function and cortical circuitry, throughout life. These changes constitute the mechanism of perceptual learning in normal visual experience and in recovery of function after CNS damage. Such plasticity can be seen at multiple stages in the visual pathway, including primary visual cortex. The manifestation of the functional changes associated with perceptual learning involve both long term modification of cortical circuits during the course of learning, and short term dynamics in the functional properties of cortical neurons. These dynamics are subject to top‐down influences of attention, expectation and perceptual task. As a consequence, each cortical area is an adaptive processor, altering its function in accordance to immediate perceptual demands.
What is remembered? Role of attention on the encoding and retrieval of hippocampal representations
Authors: Muzzio Isabel A. , Kentros Clifford , Kandel Eric
Published: June 2009

The hippocampus is critically involved in storing explicit memory such as memory for space. A defining feature of explicit memory storage is that it requires attention both for encoding and retrieval. Whereas, a great deal is now known about the mechanisms of storage, the mechanisms whereby attention modulates the encoding and retrieval of space and other hippocampus‐dependent memory representations are not known. In this review we discuss recent studies, including our own, which show on the cellular level that attention is critical for the stabilization of spatial and reward‐associated odour representations. Our findings support the view that in the hippocampus attention selects the reference frame for task‐relevant information. This mechanism is in part mediated by dopamine acting through D1/D5 receptors and involves an increase in neuronal synchronization in the gamma band frequency. We propose that synchronous activity leads to enhancements in synaptic strength that mediate the stabilization of hippocampal representations.
The Meaning of the Point of Maximum Oscillations in Cuff Pressure in the Indirect Measurement of Blood Pressure—Part II
Authors: Mauck G. W. , Smith C. R. , Geddes L. A. , Bourland J. D.
Published: June 2009

When measuring blood pressure indirectly, oscillations in the cuff pressure are observed. The cuff pressure for which these oscillations reach a maximum and its relationship to the true mean arterial pressure was investigated using a simple one-dimensional theoretical model of the cuff-arm-artery system. Results from this model indicate that the cuff pressure for maximal oscillation is strongly dependent on compression chamber air volume, pulse pressure, and arterial elasticity. Parallel experimental studies indicate general agreement with the theoretical model. The cuff pressure for maximal oscillations appears to provide a reasonable estimation of the true mean arterial pressure provided compression chamber air volume is kept small.
The Design, Fabrication and Evaluation of a Trileaflet Prosthetic Heart Valve
Authors: Chetta G. E. , Lloyd J. R.
Published: June 2009

Although prosthetic heart valves have been in existence for many years, the need for new improved designs and in-vitro evaluation techniques are apparent. This paper presents details on the design considerations, fabrication techniques and heart valve evaluation equipment. A valve performance index is discussed in light of various valve and mock circulatory test section designs. The need for national and indeed international valve evaluation techniques is made apparent.
Controlled Destruction and Temperature Distributions in Biological Tissues Subjected to Monoactive Electrocoagulation
Authors: Erez A. , Shitzer A.
Published: June 2009

An analysis of the temperature fields developed in a biological tissue undergoing a monoactive electrical coagulating process is presented, including thermal recovery following prolonged heating. The analysis is performed for the passage of alternating current and assumes a homogeneous and isotropic tissue model which is uniformly perfused by blood at arterial temperature. Solution for the one-dimensional spherical geometry is obtained by a Laplace transform and numerical integrations. Results obtained indicate the major role which blood perfusion plays in determining the effects of the coagulating process; tissue temperatures and depth of destruction are drastically reduced as blood perfusion increases. Metabolic heat generation rate is found to have negligible effects on tissue temperatures whereas electrode thermal inertia affects temperature levels appreciably. However, electrodes employed in practice would have a low thermal inertia which might be regarded as zero for all practical purposes. It is also found that the depth of tissue destruction is almost directly proportional to the electrical power and duration of application. To avoid excessively high temperatures and charring, it would be advantageous to reduce power and increase the time of application. Results of this study should be regarded as a first approximation to the rather complex phenomena associated with electrocoagulation. They may, nevertheless, serve as preliminary guidelines to practicing surgeons applying this technique.
Biphasic Creep and Stress Relaxation of Articular Cartilage in Compression: Theory and Experiments
Authors: Mow V. C. , Kuei S. C. , Lai W. M. , Armstrong C. G.
Published: June 2009

Articular cartilage is a biphasic material composed of a solid matrix phase (∼ 20 percent of the total tissue mass by weight) and an interstitial fluid phase (∼ 80 percent). The intrinsic mechanical properties of each phase as well as the mechanical interaction between these two phases afford the tissue its interesting rheological behavior. In this investigation, the solid matrix was assumed to be intrinsically incompressible, linearly elastic and nondissipative while the interstitial fluid was assumed to be intrinsically incompressible and nondissipative. Further, it was assumed that the only dissipation comes from the frictional drag of relative motion between the phases. However, more general constitutive equations, including a viscoelastic dissipation of the solid matrix as well as a viscous dissipation of interstitial fluid were also developed. A constant “average” permeability of the tissue was assumed, i.e., independent of deformation, and a solid content function Vs/Vf (the ratio of the volume of each of the phases) was assumed to vary with depth in accordance with the experimentally determined weight ratios. This linear, nonhomogeneous theory was applied to describe the experimentally obtained biphasic creep and biphasic stress relaxation data via a nonlinear regression technique. The determined intrinsic “aggregate” elastic modulus, from ten creep experiments, is 0.70 ± 0.09 MN/m2 and, from six stress relaxation experiments, is 0.76 ± 0.03 MN/m2. The “average” permeability of the tissue is (0.76 ± 0.42) × 10−14 m4 /N•s. We concluded that the large spread in the permeability coefficients is due to the assumption of a constant deformation independent permeability. We also concluded that 1) a nonlinearly permeable biphasic model, where the permeability function is given by an experimentally determined empirical law: k = A(p) exp [α(p)e], can be used to describe more accurately the rheological properties of articular cartilage, and 2) the frictional drag of relative motion is the most important factor governing the fluid/solid viscoelastic properties of the tissue in compression.
Collapse of Arteries Subjected to an External Band of Pressure
Authors: Hecht A. M. , Yeh H. , Chung S. M. K.
Published: June 2009

Collapse of arteries subjected to a band of hydrostatic pressure of finite length is analyzed. The vessel is treated as a long, thin, linearly elastic, orthotropic cylindrical shell, homogeneous in composition, and with negligible radial stresses. Blood in the vessel is treated as a Newtonian fluid and the Reynolds number is of order 1. Results are obtained for effects of the following factors on arterial collapse: intraluminal pressure, length of the pressure band, elastic properties of the vessel, initial stress both longitudinally and circumferentially, blood flow Reynolds number, compressibility, and wall thickness to radius ratio. It is found that the predominant parameter influencing vessel collapse for the intermediate range of vessel size and blood flow Reynolds numbers studied is the preconstricted intraluminal pressure. For pressure bands less than about 10 vessel radii the collapse pressure increases sharply with increasing intraluminal pressure. Initial axial prestress is found to be highly stabilizing for small band lengths. The effects of fluid flow are found to be small for pressure bands of less than 100 vessel radii. No dramatic orthotropic vessel behavior is apparent. The analysis shows that any reduction in intraluminal pressure, such as that produced by an upstream obstruction, will significantly lower the required collapse pressure. Medical implications of this analysis to Legg-Perthes disease are discussed.
Correlation of Field Injuries and GM Hybrid III Dummy Responses for Lap-Shoulder Belt Restraint
Authors: Nyquist G. W. , Begman P. C. , King A. I. , Mertz H. J.
Published: June 2009

Simulated frontal, lap-shoulder belted, barrier impact tests were performed using a Volvo sedan and General Motors Hybrid III anthropomorphic test dummy. Swedish field accident injury data for this vehicle are available from another published study. For the purpose of this program, the injuries were logically subdivided into four body regions: head, neck, thorax, and lower torso. The Hybrid III has instrumentation in each of these regions. The results of three replicated tests at barrier equivalent velocities of nominally 32 and 48 km/h are discussed in terms of the field injuries, thereby providing a basis for more intelligent interpretation of future Hybrid III test results.
Heat Transfer to Blood Vessels
Authors: Chato J. C.
Published: June 2009

Heat transfer to individual blood vessels has been investigated in three configurations: a single vessel, two vessels in counterflow, and a single vessel near the skin surface. For a single vessel the Graetz number is the controlling parameter. The arterioles, capillaries, and venules have very low Graetz numbers, Gz < 0.4, and act as perfect heat exchangers in which the blood quickly reaches the tissue temperature. The large arteries and veins with Graetz numbers over 103 have virtually no heat exchange with the tissue, and blood leaves them at near the entering temperature. Heat transfer between parallel vessels in counterflow is influenced most strongly by the relative distance of separation and by the mass transferred from the artery to the vein along the length. These two effects are of the same order of magnitude, whereas the film coefficients in the blood flow are of significant but lesser importance. The effect of a blood vessel on the temperature distribution of the skin directly above it and on the heat transfer to the environment increases with decreasing depth-to-radius ratio and decreasing Biot number based on radius. The absolute magnitude of these effects is independent of other linear effects, such as internal heat generation or a superimposed one-dimensional heat flux.
Response of the Intervertebral Disk of the Rhesus Monkey to P-A Shear Stress
Authors: Lantz S. A. , Lafferty J. F. , Bowman D. A.
Published: June 2009

The relative functions of spinal elements in resisting P-A shear stress are determined from measurements of force and displacement. The response of intact, enucleate and degenerate disks are presented, as well as stress-strain characteristics of the intervertebral disk and the roles of the articular facets and the nucleus pulposus.
A Miniature Fiber Optic pH Sensor for Physiological Use
Authors: Goldstein S. R. , Peterson J. I. , Fitzgerald R. V.
Published: June 2009

A flexible 0. 4-mm-dia pH probe potentially suitable for physiological use has been developed. It is based on the concept of utilizing two single plastic fiber optic strands to illuminate and remotely sense the color change of a dye indicator contained within an acutely implanted sealed cellulosic hollow fiber permeable to hydrogen ions. A supporting electronic module provides tungsten filament illumination, light sensing with a photodiode/operational amplifier, analog and digital circuitry to provide appropriate signal averaging and processing, and a mechanical assembly to enable the optical density measurements to be made both at 560 nm and, for normalization purposes, in the red. Over the physiological pH range from 7.0 to 7.4, the fiber optic probe agrees with a standard glass pH electrode to within 0.01 pH units in buffer solutions, to within 0.017 pH units in heparinized dog blood in vitro, and it has performed successfully while implanted in the jugular vein of a sheep.
Relation of Maximal Opening of Disk Valves to Characteristics of Aortic Blood Flow
Authors: Sabbah H. N. , Stein P. D.
Published: June 2009

The maximal extent of disk opening of the Lillehei-Kaster and Bjo¨rk-Shiley aortic disk prosthetic valves was evaluated in vitro in relation to the characteristics of flow across the valve and valve orientation within the test section. The maximal opening angle of the disk of both types of prostheses was related to the mean systolic ejection rate, cardiac output, and maximal instantaneous aortic flow. Full opening of all valves occurred throughout the entire hydrodynamic range tested when the orientation of the valve was such that the disk opened in the direction of gravitational forces. However, when the valve was oriented to open against the direction of gravitational forces, less than full opening was observed at low flow rates. At such low rates of flow, the extent of opening was also dependent upon valve size. These studies indicate that full opening of the Lillehei-Kaster and Bjo¨rk-Shiley disk valves appears to be affected by the orientation of the valve relative to gravitational forces. When less than full opening occurs, it is associated with abnormally low mean systolic ejection rates and low levels of cardiac output and aortic flow. Therefore, irrespective of valve orientation, less than maximal opening with normal flow may indicate a mechanical impediment to opening.
The Response of Blood to Transient Tensile Loading
Authors: Kenner V. H. , Wieczorek D. C.
Published: June 2009

Fresh whole blood has been subjected to transient rarefactions of approximately 50 μs duration. In this loading regime blood is found to be capable of supporting propagating rarefactions of up to 3.71 MN/m2. The character of the propagation and failure is similar to that exhibited by water.
On the Relationship Between Blood Perfusion, Metabolism and Temperature in Biological Tissue Heat Balance
Authors: Shitzer A. , Kleiner M. K.
Published: June 2009

A general, one-dimensional steady-state analysis of the thermal behavior of biological tissues is presented. The three major geometries, i.e., rectangular, cylindrical and spherical, are considered along with boundary conditions of the general type. It is shown that transport of heat inside the tissue may be dominated by conduction, convection by blood perfusion, metabolism or a combination thereof. The role of each of these mechanisms is presented by suitable dimensionless parameters expressed in terms of tissue physical properties. The order of magnitude of these parameters indicates the relative importance of the various mechanisms on the transport of heat inside the tissue. It is further shown that in areas where convection by blood perfusion is dominant, tissue temperatures are almost uniform except for narrow regions near the boundaries. The occurrence of maximum temperatures inside the tissue is also studied along with the combinations of blood perfusion and heating rates which would insure that certain predetermined values are not exceeded. This work also demonstrates that the amount of heat which may be convected into the tissue by the circulatory system depends on the heating rate and the boundary conditions, as well as the blood perfusion rate. This quantity is shown to reach a finite limit as the blood perfusion rate becomes very high.
Elasticity of Small Pulmonary Arteries in the Cat
Authors: Yen R. T. , Fung Y. C. , Bingham Nancy
Published: June 2009

When synthesizing the available data of vessel elasticity of mammalian lung from the literature, the lack of data in the intermediate range of vessel sizes becomes evident. In an effort to fill this gap, the distensibility of pulmonary arteries of cats, in the range of 100–1600 μm diameter was studied as a function of the perfusion pressure. The resulting percentage changes in vessel diameter (D) were expressed as polynomials of “transmural” pressure, which is taken to be the difference between the perfusion pressure and the pleural pressure, pa − pPL, in the form D/Do=1+α(pa−pPL)−β(pa−pPL)2. where Do is the value of D when pa = pPL, and α and β are constants. Our results show that for vessels whose diameters Do are in the range of 100–200 μ;m, the mean values of D/Do are represented by α = 2.02 percent per cm H2O or 0.202 (KPa)−1, β = 0.046 percent per (cm H2O)2 or 0.046 (KPa)−2. For vessels with diameter Do greater than 200 μm, the pressure-diameter relationship is linear in the ranges tested, so that β = 0. The values of the compliance constant α (slopes of the curves) for vessels in the diameter (Do) ranges 200–300 μm, 300–400 μm, 400–600 μm, 600–1000 μm, and 1000–1600 μm are, respectively, 0.93, 0.78, 0.70, 1.10, and 2.61 percent per cm H2O, (i.e., these numbers × 10−1 (KPa)−1). Thus the compliance of the pulmonary arteries appears to be the smallest in the diameter range 400–600 μm; and that the compliance of vessels in the 1000–1600 μm range is more than twice that of the smaller vessels.
Long-Term Torsional Creep in Compact Bone
Authors: Lakes R. , Saha S.
Published: June 2009

Bovine bone specimens loaded in torsion for periods of time exceeding one month exhibit pronounced time-dependent effects. The final strain exceeded the initial strain by a factor of more than four in some cases. Creep failure was observed in two cases. The effects are not attributable to prolonged immersion in Ringer’s solution.
Electrogoniometer for the Measurement of Human Elbow Joint Rotation
Authors: Chao E. Y. , An K. N. , Askew L. J. , Morrey B. F.
Published: June 2009

Since the electrogoniometric method has been justified for the measurement of lower extremity joint motion, a similar device is developed for the measurement of elbow joint and forearm rotations. In this design, the axis of forearm rotation coincides with the anatomical axis which eliminates the cross talk existing in the regular triaxial goniometer. Although the axis of abduction-adduction is still offset from the elbow joint, special linkage arrangement was used to obtain equivalent motion. Experimental method was used to validate the accuracy of the device and model simulation was performed to emphasize the importance of accurate placement of the instrument on test subjects. Application of the present apparatus to normal subjects was studied to illustrate the range of elbow motion required in performing normal activities of daily living. This device is currently used in the functional evaluation of patients with elbow and forearm problems.
A Technique for Kinematic Modeling of Anatomical Joints
Authors: Sommer H. J. , Miller N. R.
Published: June 2009

This paper describes a general technique for fitting a spatial kinematic model to an in-vivo anatomical joint under typical physiological loading conditions. The method employs a nonlinear least squares algorithm to minimize the aggregate deviation between postulated model motion and experimentally measured anatomical joint motion over multiple joint positions. Estimation of the parameters of a universal joint with skew-oblique revolutes to best reproduce wrist motion was used as an example. Experimental motion data from the right wrists of five subjects were analyzed. The technique performed very well and produced repeatable results consistent with previous biomechanical wrist findings.
A Viscoelastic Model for Use in Predicting Arterial Pulse Waves
Authors: Holenstein R. , Niederer P. , Anliker M.
Published: June 2009

In nonlinear mathematical models of the arterial circulation, the viscoelasticity of the vessel walls has generally been neglected or only taken into account in a highly approximate manner. A new method is proposed to simulate the nonlinear viscoelastic properties of the wall material with the aid of a convolution integral of the creep function and the pressure history. With this simulation it is possible to properly describe the measured characteristics of arterial viscoelasticity. Moreover, it is utilized in a mathematical model of arterial pulse propagation to study the influence of the internal wall friction on the shape, amplitude and mean value of pressure and flow pulses. The corresponding predictions are in much better agreement with in-vivo measurements, especially for the distal part of the circulation, than those obtained without viscoelasticity.
A Biomechanical Model for Actively Controlled Snow Ski Bindings
Authors: Hull M. L. , Ramming J. E.
Published: June 2009

Active control of snow ski bindings is a new design concept which potentially offers improved protection from lower extremity injury. Implementation of this concept entails measuring physical variables and calculating loading and/or deformation in injury prone musculoskeletal components. The subject of this paper is definition of a biomechanical model for calculating tibia torsion based on measurements of torsion loading between the boot and ski. Previous control schemes have used leg displacement only to indicate tibia torsion. The contributions of both inertial and velocity-dependent torques to tibia loading are explored and it is shown that both these moments must be included in addition to displacement-dependent moments. A new analog controller design which includes inertia, damping, and stiffness terms in the tibia load calculation is also presented.