bluuebunny/crossref_metadata_2025 huggingface dataset:
Age‐induced changes in cellular membranes of imbibed soybean seed axes
Authors: Senaratna Tissa , Gusse Jenny F. , McKersie Bryan D.
Published: July 2007

The physical and chemical properties of microsomal membranes and cellular antioxidant systems were investigated in imbibed soybean (Glycine max L. Merr. cv. Maple Arrow) seeds following aging for 5 years at room temperature. The loss of germination capacity in aged seeds was associated with increased solute leakage during imbibition and with a loss of membrane phospholipid. Higher levels of free fatty acids were observed in the microsomal membranes from aged seeds. However, there was no change in fatty acid saturation. Wide angle X‐ray diffraction studies indicated the presence of gel phase in addition to liquid‐crystalline phase lipid domains in the membranes of aged seeds. Those from fresh seeds were exclusively liquid‐crystalline. Fluorescence depolarization, using diphenylhexatriene, suggested that the microviscosity of the membrane bilayer was increased by aging. Aged seeds had a lower antioxidant potential in the lipid fraction, lower tocopherol content, and reduced ascorbate:dehydroxyascorbate ratio indicating that the aging process was associated with exposure to an oxidative stress.
Evidence that H+ efflux stimulated by redox activity is independent of plasma membrane ATPase activity
Authors: Bown Alan W. , Crawford Lesley A.
Published: July 2007

Proton efflux from mesophyll cells of Asparagus sprengeri Regel was inhibited completely by diethylstilbestrol (DES) and NN'‐dicyclohexylcarbodiimide (DCCD), known inhibitors of the plasma membrane ATPase. At the concentrations of inhibitors employed, fusicoccin did not reactivate proton efflux. Subsequent addition of ferricyanide however resulted in significant rates of acidification of the medium and reduction of ferricyanide. Similar results were obtained in the light and in the dark. Thus, medium acidification in response to redox activity appears to be independent of the ATP‐dependent acidification process.
Role of plasma membrane redox activities in elongation growth in plants
Authors: Moiré D. James , Brightman Andrew O. , Wu Lian‐Ying , Barr Rita , Leak Betty , Crane Frederick L.
Published: July 2007

Comparing isolated plasma membrane vesicles and excised hypocotyl segments from etiolated seedlings of soybean [Glycine max (L.) Merr. cv. Williams], certain antiproliferative agents that inhibited growth inhibited plasma membrane redox activities. Additionally, auxins that stimulated growth stimulated plasma membrane redox activities. Hormone stimulation was restricted to NADH oxidase (determined from disappearance of NADH) and was given both by isolated plasma membranes and by a soluhilizedenzyme preparation. Comparing IAA, the native auxin regulator, and 2,4‐D, a synthetic regulator, stimulation was observed, hut the dose‐response curves were different. Yet, the dose‐response relationships of both stimulation of auxin growth and stimulation of NADH oxidase were parallel. Inhibition of auxin‐induced growth by antiproliferative drugs was more complex. Some, like actinomycin D, preferentially inhibited NADH oxidase (EC 1.6.99.2) but inhibited NADH‐ferricya‐nide oxido‐reductase (EC 1.6.99.3) as well. Others, like adriamycin, inhibited primarily the NADH‐ferricyanide oxido‐reductase. Therefore, growth control by auxin appeared to involve NADH oxidase as a rate‐limiting terminal oxidase to link electron flow from NADH to oxygen. This observation may provide a fundamental difference from animal cells. With the latter, impermeant electron acceptors such as diferric transferrin or ferricyanide fulfill such a role. In plants, these impermeant electron acceptors were without effect on growth or were growth inhibitory.
Land Reform in the Time of Neoliberalism: A Many‐Splendored Thing
Authors: Wolford Wendy
Published: July 2007

Abstract:  Over the past 20 years, land reform – defined here as the redistribution of land from large to small properties – has emerged as an important political issue in the Global South. Actors with widely differing ideological perspectives have claimed land reform as central to their political, social and economic platforms. In this paper, I compare reforms championed under the neoliberal auspices of the World Bank (the so‐called Market Led Agrarian Reforms) with those supported by popular grassroots actors such as the Movement of Landless Workers (the MST) in Brazil. I argue that although these two approaches to land reform are often considered antithetical to one another, they share a common theoretical foundation. Both are rooted in a labor theory of property that attributes the fruits of one's labor to the laborer. Where the two differ is in their interpretation of the “original sin” through which land and labor came to be misaligned: neoliberal actors see the state as the key source of land‐related inefficiency while popular grassroots actors identify the market as the key source. I analyze case material from northeastern Brazil and suggest that the institutionalization of the labor theory of property (across civil society, state and market in the region) has generated insecurities for new land reform beneficiaries who must protect their property rights with visible evidence of their productivity.
Alternative Knowledge Strategies, Competitive Environment, and Organizational Performance in Small Manufacturing Firms
Authors: Bierly Paul E. , Daly Paula S.
Published: July 2007

This study examines the relationship between knowledge strategy (exploration or exploitation) and performance, and the possible moderating role of external environment variables. Results from a sample of small manufacturing firms indicate that exploration and exploitation are distinct and complementary constructs. The relationship between exploration and performance is linear and positive, while the relationship between exploitation and performance is concave, indicating that there is a point at which focusing on exploitation leads to reduced returns. Additionally, we find that the competitive environment moderates the relationship between exploitation and performance, such that exploitation has a stronger impact on performance in stable and high–tech environments than in dynamic and low–tech environments. Exploration also has a stronger impact on performance in high–tech environments than in low–tech environments.
The Past, Present, and Future of Entrepreneurship Research: Data Analytic Trends and Training
Authors: Dean Michelle A. , Shook Christopher L. , Payne G. Tyge
Published: July 2007

Competent data analysis is essential to entrepreneurship research and to the discipline's progression. A three–study design was used to evaluate quantitative analytic trends and the adequacy of entrepreneurship doctoral training. First, trends were identified by assessing hypothesis–testing techniques in Entrepreneurship Theory and Practice and the Journal of Business Venturing. Second, top entrepreneurship scholars were surveyed regarding the importance of various quantitative analytical techniques to future research and their expectations regarding doctoral training. Third, newly minted entrepreneurship PhDs were queried regarding their perceived competence with these same techniques. These studies provide a past, present, and future perspective on data analysis techniques and competencies in entrepreneurship.
Marshaling Resources to Form Small New Ventures: Toward a More Holistic Understanding of Entrepreneurial Support
Authors: Hanlon Dennis , Saunders Chad
Published: July 2007

This article makes two contributions to our understanding of the core entrepreneurial activity of assembling resources to pursue an opportunity. First, a conceptual framework is presented to organize the research on resource mobilization. Second, a study is presented based upon interviews with a random sample of 48 entrepreneurs to identify the supporters whom the entrepreneurs considered to have been key to their success and the resources obtained from these individuals. Results indicate that maximizing the overall effectiveness of resource combinations is a complex undertaking involving trade–offs between the quantity and quality of available resources and the efficiency versus effectiveness of supporters.
Radiofrequency Ablation of Symptomatic but Benign Ventricular Arrhythmias
Authors: GURSOY SINAN , BRUGADA JOSEP , SOUZA OLGA , STEURER GUNTER , ANDRIES ERIK , BRUGADA PEDRO
Published: July 2007

GURSOY, S., et al.: Radiofrequency Ablation of Symptomatic but Benign Ventricular Arrhythmias. Two cases are presented where ablation of severely symptomatic ventricular arrhythmias not responding to medical therapy was accomplished with radiofrequency current application. After a routine programmed stimulation protocol, a quadripolar ablation catheter with a 4‐mm tip was advanced percutaneously into the left ventricle in one case and into the right ventricle in the second case; and after precise pace mapping, the arrhythmogenic focus was successfully ablated using radiofrequency current. The postablation ambulatory recording revealed virtual eradication of ventricular ectopy in both cases. In conclusion, in severely symptomatic cases of “benign” ventricular arrhythmias, radiofrequency ablation offers an effective therapeutic alternative.
Incidence and Timing of Activity Parameter Changes in Activity Responsive Pacing Systems
Authors: AHERN THOMAS , NYDEGGER CHARLES , McCORMICK DANIEL J. , MAQUILAN MARCH , SCHUSTER MELINDA , KUTALEK STEVEN P.
Published: July 2007

AHERN, T., et al.: Incidence and Timing of Activity Parameter Changes in Activity Responsive Pacing Systems. The incidence and timing of rate response parameter reprogramming in activity responsive pacing systems during the year after implantation was evaluated in two groups of patients: 24 patients in whom a VVI, R system was implanted (Activitrax, Medtronic, Inc.), and 21 patients in whom a DDD, R system was implanted (Synchrony, Siemens Pacesetter, Inc.). Activity parameter changes in Activitrax patients were made based on the presence of symptoms, while in Synchrony patients, changes were based on objective data obtained using a sensor indicated rate histogram with a slow and fast walk protocol. No significant difference in the incidence of activity parameter reprogramming was noted at various time intervals during the first year in Activitrax patients; in Synchrony patients a greater incidence of reprogramming changes was noted at the 1‐month follow‐up visit compared to later follow‐up visits (P < 0.02). Further, the incidence of changes at 1 month was greater for Synchrony compared to Activitrax patients (P < 0.001), while no difference was detected between groups at subsequent follow‐up intervals. Use of the slow and fast walk protocol, by permitting serial evaluation of sensor response, demonstrated alterations in sensor drive rates with similar levels of activity over the initial 4 to 6 postimplant weeks. This may result from postoperative changes at the pacemaker insertion site. Based on this experience, predischarge programming may not predict long‐term rate response requirements. We recommend evaluation of sensor function using an exercise protocol performed at 4 to 6 postimplant weeks in all rate responsive pacing systems that utilize a piezoelectric crystal.
Ruptured Aneurysm of the Sinus of Valsalva Associated with an Atrial Septal Aneurysm
Authors: Karavidas Apostolos , Matsakas Evangelos , Foukarakis Manolis , Panou Fotios , Dounis George , Zacharoulis Apostolos
Published: July 2007

Aneurysm of the sinus of Valsalva (ASV) is a rare cardiac disease that may be acquired or congenital. It is usually an asymptomatic condition; however, when it ruptures, symptoms appear and the condition deteriorates rapidly. Atrial septal aneurysm (ASA) is a localized “saccular” deformity of the interatrial septum that is associated with cerebrovascular events of embolic origin. We will report on a case of a 69‐year‐old woman who was referred to our department because of congestive heart failure. Echocardiographic evaluation, both transthoracic and transesophageal, disclosed a ruptured aneurysm of the right sinus of Valsalva into the right atrium (RA), which was associated with an aneurysm of the atrial septum.
Three‐Dimensional Echocardiography Using a Muliplane Transesophageal Probe:
Authors: Hozumi Takeshi , Yoshikawat Junichi
Published: July 2007

The use of multiplane transesophageal echocardiography has provided three‐dimensional image sets of the heart from multiple two‐dimensional images with high‐image quality through rotation of the transducer without changing its position (rotational scanning). We discuss the methods, clinical applications, and current limitations of this three‐dimensional technique.
Determination of Left Ventricular Volume, Ejection Fraction, and Myocardial Mass by Real‐Time Three‐Dimensional Echocardiography
Authors: Qin Jian Xin , Shiota Takahiro , Thomas James D.
Published: July 2007

Reconstructed three‐dimensional (3‐D) echocardiography is an accurate and reproducible method of assessing left ventricular (LV) functions. However, it has limitations for clinical study due to the requirement of complex computer and echocardiographic analysis systems, electrocardiographic/respiratory gating, and prolonged imaging times. Real‐time 3‐D echocardiography has a major advantage of conveniently visualizing the entire cardiac anatomy in three dimensions and of potentially accurately quantifying LV volumes, ejection fractions, and myocardial mass in patients even in the presence of an LV aneurysm. Although the image quality of the current real‐time i echocardiographic methods is not optimal, its widespread clinical application is possible because of the convenient and fast image acquisition. We review real‐time 3‐D echocardiographic image acquisition and quantitative analysis for the evaluation of LV function and LVmass.
In vitro differentiation of human mesenchymal stem cells to epithelial lineage
Authors: Păunescu Virgil , Deak Erika , Herman Diana , Siska Ioana Raluca , T˘anasie Gabriela , Bunu Carmen , Anghel Simona , Tatu Calin A. , Oprea Tudor I. , Henschler Reinhard , Rüster Brigitte , Bistrian Roxana , Seifried Erhard
Published: July 2007

Our study examined whether human bone marrow‐derived MSCs are able to differentiate, in vitro, into functional epithelial‐like cells. MSCs were isolated from the sternum of 8 patients with different hematological disorders. The surface phenotype of these cells was characterized.To induce epithelial differentiation, MSCs were cultured using Epidermal Growth Factor, Keratinocyte Growth Factor, Hepatocyte Growth Factor and Insulin‐like growth Factor‐II. Differentiated cells were further characterized both morphologically and functionally by their capacity to express markers with specificity for epithelial lineage. The expression of cytokeratin 19 was assessed by immunocytochemistry, and cytokeratin 18 was evaluated by quantitative RT‐PCR (Taq‐man). The data demonstrate that human MSCs isolated from human bone marrow can differentiate into epithelial‐like cells and may thus serve as a cell source for tissue engineering and cell therapy of epithelial tissue.
Colon cancer metastasis in mouse liver is not affected by hypercoagulability due to Factor V Leiden mutation
Authors: Klerk C.P.W. , Smorenburg S.M. , Spek C.A. , Van Noorden C.J.F.
Published: July 2007

Clinical trials have shown life‐prolonging effects of antithrombotics in cancer patients, but the molecular mechanisms remain unknown due to the multitude of their effects. We investigated in a mouse model whether one of the targets of antithrombotic therapy, fibrin deposition, stimulates tumour development. Fibrin may provide either protection of cancer cells in the circulation against mechanical stress and the immune system, or form a matrix for tumours and/or angiogenesis in tumours to develop. Mice homozygous for Factor V Leiden (FVL), a mutation in one of the coagulation factors that facilitates fibrin formation, were used to investigate whether hypercoagulability affects tumour development in an experimental metastasis model. Liver metastases of colon cancer were induced in mice with the FVL mutation and wild‐type littermates. At day 21, number and size of tumours at the liver surface, fibrin/fibrinogen distribution, vessel density and the presence of newly formed vessels in tumours were analysed. Number and size of tumours did not differ between mice with and without the FVL mutation. Fibrin/fibrinogen was found in the cytoplasm of hepatocytes and cancer cells, in blood vessels in liver and tumour tissue and diffusely distributed outside vessels in tumours, indicating leaky vessels. Vessel density and angiogenesis varied widely between tumours, but a pre‐dominance for vessel‐rich or vessel‐poor tumours or vessel formation could not be found in either genotype. In conclusion, the FVL mutation has no effect on the development of secondary tumours of colon cancer in livers of mice. Fibrin deposition and thus inhibition of fibrin formation by anticoagulants do not seem to affect tumour development in this model.
Where Next in Victorian Literary Studies? –‘Interesting Times’ and the Lesson of ‘A Corner in Lightning’
Authors: Amigoni David
Published: July 2007

This paper forms part of a Literature Compass cluster of articles which examines the current state of Victorian Literary Studies and future directions. This group of four essays was originally commissioned by Francis O’Gorman (University of Leeds), who also provides an introduction to the cluster.

The full cluster is made up of the following articles:

‘Where Next in Victorian Literary Studies? – Introduction’, Francis O’Gorman, Literature Compass 4 (2007), 10.1111/j.1741‐4113.2007.00467.x.

‘Where Next in Victorian Literary Studies? – Revising the Canon, Extending Cultural Boundaries, and the Challenge of Interdisciplinarity’, Joanne Shattock, Literature Compass 4 (2007), 10.1111/j.1741‐4113.2007.00468.x.

‘Where Next in Victorian Literary Studies? –“Interesting Times” and the Lesson of “A Corner in Lightning”’, David Amigoni, Literature Compass 4 (2007), 10.1111/j.1741‐4113.2007.00469.x.

‘Where Next in Victorian Literary Studies? – Historicism, Collaboration and Digital Editing’, Valerie Sanders, Literature Compass 4 (2007), 10.1111/j.1741‐4113.2007.00470.x.

‘Where Next in Victorian Literary Studies? – Historicism and Hospitality’, John Bowen, Literature Compass 4 (2007), 10.1111/j.1741‐4113.2007.00471.x.

***

The question ‘where next in Victorian literary studies’ involves thinking simultaneously about the revolution in communications which constituted Victorian culture, and the digital revolution of our present. The article considers the challenges faced by Victorian literary studies in a number of contexts: the production and dissemination of contemporary scholarship; interdisciplinarity as evidenced in the science‐literature relationship; the question of periodisation as evidenced in the study of the Victorian novel and historiography; and finally the question of the ‘globalising’ turn in Victorian Studies which is illustrated through a reading of George Griffiths's 1898 scientific romance ‘A Corner in Lightning’.
Uncertainty in Clinical Research
Authors: Levine Robert J.
Published: July 2007

“It is a fact of life that human beings find it difficult to maintain a consistent, self-conscious appreciation of the extent to which uncertainty accompanies them on their daily rounds and to integrate that uncertainty with whatever certainties inform their conduct. Physicians are not exempt from this human proclivity.”

—Jay Katz
A “Dignitary Tort” as a Bridge between the Idea of Informed Consent and the Law of Informed Consent
Authors: Meisel Alan
Published: July 2007

More than 30 years have passed since the phrase informed consent was first uttered in a judicial opinion. Jay Katz's own ground-breaking work on informed consent is now more than 10 years old, and the insights ofThe Silent World of Doctor and Patientare so constantly fresh that it is easy to forget it too was not just recently published. While trying to develop some new thoughts about informed consent for this essay—a task made virtually impossible by Jay's work—I had reviewed an article by Professor Joseph Goldstein, one of Jay's frequent collaborators. Goldstein recounted discovering an index card he had written almost 30 years earlier (ironically for me, the year I was born) containing some notes about Harold Lasswell's work. Not only is law a seamless web, it is a timeless one.

Jay's work on informed consent is pervaded by a timeless theme that I wish to address here: how the dignity of the individual, the shining beacon of the idea of informed consent, is sorely neglected in the law of informed consent.
Professional Liability and the Quality of Mental Health Care
Authors: Bonnie Richard J.
Published: July 2007

Any lawyer in a gathering of health professionals, especially physicians, can expect to be bombarded by complaints about the law of professional liability and the high cost of malpractice insurance. It is well-established, of course, that the number of medical malpractice claims significantly increased in the 1960s, precipitating the first insurance crisis in the early 1970s, and leading to a wave of legislative reforms. Now, after a quiescent period, the number of claims filed and the cost of insurance are rising again, and the legislatures have responded with a new wave of reforms.

According to the American Medical Association's socio-economic monitoring system, the number of claims filed against physicians increased from an average annual rate of 3.2 per 100 physicians before 1981 to 8.2 from 1981-1984 and to 10.1 in 1985. The annual cost of insurance premiums, which had increased only by 4 percent per year from 1976 to 1982, increased by an annual average of 21.9 percent between 1983 and 1985. The cost of insurance represents about 4 percent of the gross revenues of the average self-employed physician.
The Silent World of Collaborators from Different Disciplines
Authors: Goldstein Joseph
Published: July 2007

For ten years, starting in 1958, Jay Katz and I were each other's teachers and each other's students in a teaching and writing collaboration at the Yale Law School. What was the nature of the collaborative relationship that Jay the physician-psychiatrist-psychoanalyst-in-training and I, trained in law and political science, expected to establish? Were we making informed choices when we entered into, carried out and ended our collaboration? Did we recome and acknowledge to ourselves and to each other why we were doing what we did? In accord with Jay's prescriptions in The Silent World of Doctor and Patient—a monumental contribution to our thinking about another collaboration—did we seek to help each other understand the decisions we had reached?

A word, first, about the kind of collaboration described in this essay. In a fundamental sense all intellectual and scholarly work—even work in the creative arts—is collaborative. All who engage in these activities build on or respond to the work of others.
“I Think I Do”: Another Perspective on Consent and the Law
Authors: Baker Lynn A.
Published: July 2007

The doctrine of informed consent, introduced by the courts in 1957, is but one of many legally imposed duties to disclose to arise over the last several decades. In myriad areas of everyday life, including medical decision-making, the law has come to require that a person or entity with presumptively superior information as to risks, contents, or consequences take affirmative steps to disclose that information at the time another individual is faced with a decision for which it might prove pertinent.

Such disclosure requirements underscore the values of individual liberty and self-determination that are at the core of our rights-based legal system. Rather than directly and more paternalistically regulating citizen behavior by, for example, simply prohibiting a given riskcreating activity, the State takes the less intrusive step of mandating that the individual be provided information that might affect her behavior.
Using Litigation to Make Public Health Policy: Theoretical and Empirical Challenges in Assessing Product Liability, Tobacco, and Gun Litigation
Authors: Lytton Timothy D.
Published: July 2007

In recent years, a number of prominent scholars have touted the use of litigation as an effective tool for making public health policy. For example, Stephen Teret and Michael Jacobs have asserted that product liability claims against car makers have played a significant role in reducing automobile-related injuries, Peter Jacobson and Kenneth Warner have argued that litigation against cigarette manufacturers has advanced the cause of tobacco control, and Phil Cook and Jens Ludwig have suggested that lawsuits against the firearms industry can reduce gun violence. Critics have attacked this use of litigation as doing more harm than good to public health and as a misuse of the courts. This debate involves two distinct controversies: one over whether the public health benefits of litigation outweigh its costs and the other over the proper role of courts within our system of government.
Pandemic Influenza: Public Health Preparedness for the Next Global Health Emergency
Authors: Gostin Lawrence O.
Published: July 2007

The threat posed by avian influenza appears to be rising, yet global and national health programs are preparing only fitfully. A lethal form of avian flu has rooted itself deeply into the poultry flocks of poor Asian countries that will have a hard time eradicating it. Every so often a sick bird infects a human, who usually dies from the encounter, and on rare occasions the virus seems to have spread from one person to another before the chain of infection dies out. All it would take to set off a raging global pandemic would be for the virus to mutate into a form that is readily transmissible among humans.

Severe Acute Respiratory Syndrome (SARS) garnered a great deal of public attention because it was novel and its potential for spread was unknown. However, the SARS corona virus is significantly less virulent than pandemic influenza viral infections.
What are the Limits of Bioethics in a Culturally Pluralistic Society?
Authors: Bowman Kerry
Published: July 2007

Modern bioethics, which is based on Western moral philosophy and Western biomedical perspectives, has evolved within a complex, highly individualistic culture that draws a sharp distinction between church and state and tolerates a multitude of values. This discipline defines its principles in secular and objective terms that often are bewildering to people of non-Western origin. Despite much discourse, principlism remains the fundamental framework of bioethics. Principlism is held in such high regard that many bioethicists equate autonomy with personhood, as if autonomy exists independently of specific beliefs and commitments.

In addition, we continue to minimize the substantial differences in the way people of different cultures perceive, experience, and explain illness, although our views of the potential cultural limitations of Western medicine have grown and expanded in recent years. At the heart of it we continue to be tied to a biomedical focus that largely neglects the context of the situation.
Disputes about the Withdrawal of Treatment: The Role of the Courts
Authors: Skene Loane
Published: July 2007

It is commonly said that patients (or their representatives) have no right to demand that treatment must be continued when medical carers believe it is “futile” to continue it. There are certainly many judicial statements to this effect, some of which are quoted in this paper. However, there are various ways that courts can intervene, even if they do not order directly that treatment must be provided or continued. First, patients or their representatives may argue the process of decision making was unfair or that they were unfairly discriminated against when treatment has been refused. To date, these arguments have met with limited success so far as enabling patients to have treatment provided or continued against medical advice. More recently, however, some patients have challenged the lawfulness of a proposed treatment regime by advancing human rights arguments, based in turn on a broader aspect of patients’ “best interests” than best medical interests.
Developmental regulation of the membrane properties of central vestibular neurons by sensory vestibular information in the mouse
Authors: Eugène D. , Deforges S. , Guimont F. , Idoux E. , Vidal P.‐P. , Moore L. E. , Vibert N.
Published: July 2007

The effect of the lack of vestibular input on the membrane properties of central vestibular neurons was studied by using a strain of transgenic, vestibular‐deficient mutant KCNE1−/− mice where the hair cells of the inner ear degenerate just after birth. Despite the absence of sensory vestibular input, their central vestibular pathways are intact. Juvenile and adult homozygous mutant have a normal resting posture, but show a constant head bobbing behaviour and display the shaker/waltzer phenotype characterized by rapid bilateral circling during locomotion. In juvenile mice, the KCNE1 mutation was associated with a strong decrease in the expression of the calcium‐binding proteins calbindin, calretinin and parvalbumin within the medial vestibular nucleus (MVN) and important modifications of the membrane properties of MVN neurons. In adult mice, however, there was almost no difference between the membrane properties of MVN neurons of homozygous and control or heterozygous mutant mice, which have normal inner ear hair cells and show no behavioural symptoms. The expression levels of calbindin and calretinin were lower in adult homozygous mutant animals, but the amount of calcium‐binding proteins expressed in the MVN was much greater than in juvenile mice. These data demonstrate that suppression of sensory vestibular inputs during a ‘sensitive period’ around birth can generate the circling/waltzing behaviour, but that this behaviour is not due to persistent abnormalities of the membrane properties of central vestibular neurons. Altogether, maturation of the membrane properties of central vestibular neurons is delayed, but not impaired by the absence of sensory vestibular information.
Muscle responses to transcranial stimulation in man depend on background oscillatory activity
Authors: Mitchell W. Kyle , Baker Mark R. , Baker Stuart N.
Published: July 2007

Muscle responses to transcranial stimulation show high sweep‐to‐sweep variability, which may reflect an underlying noise process in the motor system. We examined whether response amplitude correlated with the level of prestimulus background EMG, and network oscillations. Transcranial magnetic or electrical stimulation was delivered to primary motor cortex whilst human subjects performed a precision grip task known to promote beta‐band (∼20 Hz) cortical oscillations. Responses were recorded from two intrinsic hand muscles. Response magnitude correlated significantly with the level of background EMG (mean r2= 0.20). Using a novel wavelet method, we quantified the amplitude and phase of oscillations in prestimulus sensorimotor EEG. Surprisingly, response magnitude showed no significant correlation with EEG oscillations at any frequency. However, oscillations in the prestimulus EMG were significantly correlated with response size; the correlation coefficient had peaks around 20 Hz. When oscillations in one muscle were used to predict response amplitude in a different muscle, correlations were substantially smaller. Finally, for each recording, we calculated the best possible prediction of response size obtainable from up to 20 measures of prestimulus EEG and EMG oscillations. Such optimal predictions had low correlation coefficients (mean r2= 0.2; 76% were below 0.3). We conclude that prestimulus oscillations, mainly in the beta‐band, do explain some of the variability in responses to transcranial stimulation. Oscillations may likewise increase the noise of natural motor processing, explaining why this form of network activity is usually suppressed prior to dynamic movements. However, the majority of the variation is determined by other factors, which are not accessible by noninvasive recordings.
Genetic deletion of SK2 channels in mouse inner hair cells prevents the developmental linearization in the Ca2+ dependence of exocytosis
Authors: Johnson Stuart L. , Adelman John P. , Marcotti Walter
Published: July 2007

Inner hair cells (IHCs), the primary sensory receptors of the mammalian cochlea, fire spontaneous Ca2+ action potentials (APs) only before the onset of hearing. Although a role for APs in the developing auditory system has not been determined it could, by analogy with other sensory systems, guide the functional maturation of the cochlea before experience‐driven activity begins. Spontaneous APs in immature IHCs are shaped by a variety of ion channels including that of the small conductance Ca2+‐activated K+ current (SK2), which is only transiently expressed in immature cells. Using SK2 knockout mice we found that SK2 channels are not required for generating APs but are essential for sustaining continuous repetitive spontaneous AP activity in pre‐hearing IHCs. Therefore we used this mutant mouse as a model to study possible developmental implications of disrupted AP activity. Immature mutant IHCs showed impaired exocytotic responses, which are likely to be due to the expression of fewer Ca2+ channels. Exocytosis was also impaired in adult mutant IHCs, although in this case it resulted from a reduced Ca2+ efficiency and increased Ca2+ dependence of the synaptic machinery. Since SK2 channels can only have a functional influence on IHCs during immature development and are not directly involved in neurotransmitter release, the altered Ca2+ dependence of exocytosis in adult IHCs is likely to be a consequence of their disrupted AP activity at immature stages.
Reorganized stores and impaired calcium handling in skeletal muscle of mice lacking calsequestrin‐1
Authors: Paolini Cecilia , Quarta Marco , Nori Alessandra , Boncompagni Simona , Canato Marta , Volpe Pompeo , Allen Paul D. , Reggiani Carlo , Protasi Feliciano
Published: July 2007

Calsequestrin (CS), the major Ca2+‐binding protein in the sarcoplasmic reticulum (SR), is thought to play a dual role in excitation–contraction coupling: buffering free Ca2+ increasing SR capacity, and modulating the activity of the Ca2+ release channels (RyRs). In this study, we generated and characterized the first murine model lacking the skeletal CS isoform (CS1). CS1‐null mice are viable and fertile, even though skeletal muscles appear slightly atrophic compared to the control mice. No compensatory increase of the cardiac isoform CS2 is detectable in any type of skeletal muscle. CS1‐null muscle fibres are characterized by structural and functional changes, which are much more evident in fast‐twitch muscles (EDL) in which most fibres express only CS1, than in slow‐twitch muscles (soleus), where CS2 is expressed in about 50% of the fibres. In isolated EDL muscle, force development is preserved, but characterized by prolonged time‐to‐peak and half‐relaxation time, probably related to impaired calcium release from and re‐uptake by the SR. Ca2+‐imaging studies show that the amount of Ca2+ released from the SR and the amplitude of the Ca2+ transient are significantly reduced. The lack of CS1 also causes significant ultrastructural changes, which include: (i) striking proliferation of SR junctional domains; (ii) increased density of Ca2+‐release channels (confirmed also by 3H‐ryanodine binding); (iii) decreased SR terminal cisternae volume; (iv) higher density of mitochondria. Taken together these results demonstrate that CS1 is essential for the normal development of the SR and its calcium release units and for the storage and release of appropriate amounts of SR Ca2+.
A New Microcontact Model Developed for Variable Fractal Dimension, Topothesy, Density of Asperity, and Probability Density Function of Asperity Heights
Authors: Luen Liou Jeng , Fin Lin Jen
Published: July 2007

In the present study, the fractal theory is applied to modify the conventional model (the Greenwood and Williamson model) established in the statistical form for the microcontacts of two contact surfaces. The mean radius of curvature (R) and the density of asperities (η) are no longer taken as constants, but taken as variables as functions of the related parameters including the fractal dimension (D), the topothesy (G), and the mean separation of two contact surfaces. The fractal dimension and the topothesy varied by differing the mean separation of two contact surfaces are completely obtained from the theoretical model. Then the mean radius of curvature and the density of asperities are also varied by differing the mean separation. A numerical scheme is thus developed to determine the convergent values of the fractal dimension and topothesy corresponding to a given mean separation. The topographies of a surface obtained from the theoretical prediction of different separations show the probability density function of asperity heights to be no longer the Gaussian distribution. Both the fractal dimension and the topothesy are elevated by increasing the mean separation. The density of asperities is reduced by decreasing the mean separation. The contact load and the total contact area results predicted by variable D, G*, and η as well as non-Gaussian distribution are always higher than those forecast with constant D, G*, η, and Gaussian distribution.
Quasi-Static Biaxial Plastic Buckling of Tubular Structures Used as an Energy Absorber
Authors: Baleh R. , Abdul-Latif A.
Published: July 2007

The aim of this experimental study is to improve the energy absorption capacity of tubular metallic structures during their plastic buckling by increasing the strength properties of materials. Based on a novel idea, a change in the plastic strength of materials could be predictable through the loading path complexity concept. An original experimental device, which represents a patent issue, is developed. From a uniaxial loading, a biaxial (combined compression–torsion) loading path is generated by means of this device. Tests are carried out to investigate the biaxial plastic buckling behavior of several tubular structures made from copper, aluminum, and mild steel. The effects of the loading path complexity, the geometrical parameters of the structures, and loading rates (notably the tangential one) on the plastic flow mechanism, the mean collapse load, and the energy absorbed are carefully analyzed. The results related to the copper and aluminum metals show that the plastic strength properties of the tubes crushed biaxially change with the torsional component rate. This emphasizes that the energy absorption improves with increasing the applied loading complexity. However, the energy absorbed data for the mild steel tubular structures do not demonstrate the same sensitivity to the quasi-static loading path complexity.
Effect of Surface Elasticity on the Interaction Between Steps
Authors: Huang Gan-Yun , Yu Shou-Wen
Published: July 2007

By taking into account the effect of surface elasticity, the problem of a half plane under concentrated normal or shear loads is first considered. The solutions for the displacements or alternatively named surface Green’s functions can be obtained by using the Fourier integral transform technique. Based on such solutions, the elastic interaction between two surface steps that are modeled as force dipoles is further investigated. The results show that the effect of surface elasticity on the interaction energy is significant when the distance between the two steps is in the range of several times the intrinsic length scale of the system. Further, surface elasticity seems to influence the interaction between steps with force components parallel to the surface more strongly than that when the steps exhibit force components only normal to the surface.
Effect of Boundary Conditions on Nonlinear Vibrations of Circular Cylindrical Panels
Authors: Amabili M.
Published: July 2007

Geometrically nonlinear vibrations of circular cylindrical panels with different boundary conditions and subjected to harmonic excitation are numerically investigated. The Donnell’s nonlinear strain–displacement relationships are used to describe geometric nonlinearity; in-plane inertia is taken into account. Different boundary conditions are studied and the results are compared; for all of them zero normal displacements at the edges are assumed. In particular, three models are considered in order to investigate the effect of different boundary conditions: Model A for free in-plane displacement orthogonal to the edges, elastic distributed springs tangential to the edges and free rotation; Model B for classical simply supported edges; and Model C for fixed edges and distributed rotational springs at the edges. Clamped edges are obtained with Model C for the very high value of the stiffness of rotational springs. The nonlinear equations of motion are obtained by the Lagrange multimode approach, and are studied by using the code AUTO based on the pseudo-arclength continuation method. Convergence of the solution with the number of generalized coordinates is numerically verified. Complex nonlinear dynamics is also investigated by using bifurcation diagrams from direct time integration and calculation of the Lyapunov exponents and the Lyapunov dimension. Interesting phenomena such as (i) subharmonic response; (ii) period doubling bifurcations; (iii) chaotic behavior; and (iv) hyper-chaos with four positive Lyapunov exponents have been observed.
Engine Design Studies for a Silent Aircraft
Authors: Hall Cesare A. , Crichton Daniel
Published: July 2007

The Silent Aircraft Initiative is a research project funded by the Cambridge-MIT Institute aimed at reducing aircraft noise to the point where it is imperceptible in the urban environments around airports. The propulsion system being developed for this project has a thermodynamic cycle based on an ultrahigh bypass ratio turbofan combined with a variable area exhaust nozzle and an embedded installation. This cycle has been matched to the flight mission and thrust requirements of an all-lifting body airframe, and through precise scheduling of the variable exhaust nozzle, the engine operating conditions have been optimized for maximum thrust at top-of-climb, minimum fuel consumption during cruise, and minimum jet noise at low altitude. This paper proposes engine mechanical arrangements that can meet the cycle requirements and, when installed in an appropriate airframe, will be quiet relative to current turbofans. To reduce the engine weight, a system with a gearbox, or some other form of shaft speed reduction device, is proposed. This is combined with a low-speed fan and a turbine with high gap-chord spacing to further reduce turbomachinery source noise. An engine configuration with three fans driven by a single core is also presented, and this is expected to have further weight, fuel burn, and noise benefits.
Integration of Possibility-Based Optimization and Robust Design for Epistemic Uncertainty
Authors: Youn Byeng D. , Choi Kyung K. , Du Liu , Gorsich David
Published: July 2007

In practical engineering applications, there exist two different types of uncertainties: aleatory and epistemic uncertainties. This study attempts to develop a robust design optimization with epistemic uncertainty. For epistemic uncertainties, a possibility-based design optimization improves the failure rate, while a robust design optimization minimizes the product quality loss. In general, product quality loss is described using the first two statistical moments for aleatory uncertainty: mean and standard deviation. However, there is no metric for product quality loss defined when having epistemic uncertainty. This paper first proposes a new metric for product quality loss with epistemic uncertainty, and then a possibility-based robust design optimization. For numerical efficiency and stability, an enriched performance measure approach is employed for possibility-based robust design optimization, and the maximal possibility search is used for a possibility analysis. Three different types of robust objectives are considered for possibility-based robust design optimization: smaller-the-better type (S-Type), larger-the-better type (L-Type), and nominal-the-better type (N-Type). Examples are used to demonstrate the effectiveness of possibility-based robust design optimization using the proposed metric for product quality loss with epistemic uncertainty.
Integrated Design Toolbox for Tripod-Based Parallel Kinematic Machines
Authors: Bi Z. M. , Lang S. Y. T. , Zhang D. , Orban P. E. , Verner M.
Published: July 2007

This paper presents a concept and implementation of a toolbox for design and application of tripod-based parallel kinematic machines (PKMs). The toolbox is a suite of design tools to support users from conceptual design to actual application of tripod-based PKMs. These design tools have been individually developed in different languages and development environments, and are integrated seamlessly using a JAVA-based platform. Users can access all the design tools through a friendly graphical user interface (GUI). It is the first computer-aided design system specially developed for tripod-based PKMs. The toolbox includes some innovative methodologies, such as a forward kinematics solver, the concept of joint workspace, on-line monitoring based on forward kinematics, and the concept of motion purity. The paper gives an overview on the toolbox architecture and some key technologies.
Product-Oriented Sensitivity Analysis for Multistation Compliant Assemblies
Authors: Yue Jianpeng , Camelio Jaime A. , Chin Melida , Cai Wayne
Published: July 2007

Dimensional variation in assembled products directly affects product performance. To reduce dimensional variation, it is necessary that an assembly be robust. A robust assembly is less sensitive to input variation from the product and process components, such as incoming parts, subassemblies, fixtures, and welding guns. In order to effectively understand the sensitivity of an assembly to input variation, an appropriate set of metrics must be defined. In this paper, three product-oriented indices, including pattern sensitivity index, component sensitivity index, and station sensitivity index, are defined. These indices can be utilized to measure the variation influence of a pattern, an individual part, and/or component, and components at a particular station to the dimensional quality of a final assembly. Additionally, the relationships among these sensitivity indices are established. Based on these relationships, the ranges of the sensitivity indices are derived. Finally, a case study of a sheet metal assembly is presented and discussed to illustrate the applicability of these metrics.
A Simple Method for Inverse Kinematic Analysis of the General 6R Serial Robot
Authors: Xin Shi Zhi , Feng Luo Yu , Bing Hang Lu , Li Yang Ting
Published: July 2007

The inverse kinematic analysis of the general 6R serial robot has been a very significant and important problem in the theory of the spatial mechanisms. Because the solution to inverse kinematics problem of the general 5R serial robot is unique and its assembly condition has been derived, a simple effective method for inverse kinematics problem of general 6R serial robot or forward kinematics problem of general 7R single-loop mechanism is presented based on a one-dimension searching algorithm. All the real solutions to inverse kinematics problems of the general 6R serial robot or forward kinematics problems of the general 7R single-loop mechanism can be obtained. The new method has the following features: (1) using one-dimension searching algorithm, all the real inverse kinematic solutions are obtained and it has higher computing efficiency; and (2) compared with the algebraic method, it has evidently reduced the difficulty of deducing formulas. The principle of the new method can be generalized to kinematic analysis of parallel mechanisms.