bluuebunny/crossref_metadata_2025 huggingface dataset:
Knowledge Integration and Dynamic Organizational Adaptation in Family Firms
Authors: Chirico Francesco , Salvato Carlo
Published: May 2008

The speed of change in competitive environments has prompted firms to develop processes directed at enabling organizational adaptation. This is captured by the concept of dynamic capabilities. We focus on a particular form of business organization, that is, the family firm. Specifically, we argue that knowledge integration—a dynamic capability through which family members' specialized knowledge is recombined—guides the evolution of capabilities. We present a general framework illustrating factors that affect knowledge integration in family firms. We conclude that only those family firms that are able to effectively integrate individual family members' specialized knowledge will be successful in dynamic markets by changing their capabilities over time.
Metformin Induces Cardioprotection against Ischaemia/Reperfusion Injury in the Rat Heart 24 Hours after Administration
Authors: Solskov Lasse , Løfgren Bo , Kristiansen Steen B. , Jessen Niels , Pold Rasmus , Nielsen Torsten T. , Bøtker Hans Erik , Schmitz Ole , Lund Sten
Published: May 2008

Abstract:  The UK Prospective Diabetes Study demonstrated that the hypoglycaemic drug metformin is associated with a reduction in cardiovascular events in a group of obese type 2 diabetes patients. The energy sensing enzyme AMP‐activated protein kinase (AMPK) has been indicated to play an important protective role in the ischaemic heart and is activated by metformin. The aim of this study was to determine whether a single dose of metformin protects the myocardium against experimentally induced ischaemia 24 hr after the administration, and furthermore to determine whether a single dose of metformin results in an acute increase in myocardial AMPK activity. Wistar rats were given either a single oral dose of metformin (250 mg/kg body weight), or a single oral dose of saline. After 24 hr, the hearts were Langendorff‐perfused and subjected to 45 min. of coronary artery occlusion. Infarct size was determined by staining with triphenyltetrazoliumchloride (TTC) and Evans Blue and expressed as a percentage of the risk zone (IS/AAR %). Isoform specific AMPK activity was measured 2 hr after administration of metformin or saline. Infarct size was significantly reduced in the metformin treated (I/R: 19.9 ± 3.9%versus 36.7 ± 3.6%, P < 0.01, n = 8–14) compared to the control group. A single oral dose of metformin resulted in an approximately ~2‐fold increase in AMPK‐α2 activity 2 hr after administration (P < 0.015, n = 10). In conclusion, a single dose of metformin results in an acute increase in myocardial AMPK activity measured 2 hr after administration and induces a significant reduction in myocardial infarct size 24 hr after metformin administration. Increased AMPK activity may be an important signal mediator involved in the mechanisms behind the cardioprotective effects afforded by metformin.
Improving Person‐Fit Assessment by Correcting the Ability Estimate and Its Reference Distribution
Authors: De La Torre Jimmy , Deng Weiling
Published: May 2008

The standardized log‐likelihood of a response vector (lz) is a popular IRT‐based person‐fit test statistic for identifying model‐misfitting response patterns. Traditional use of lz is overly conservative in detecting aberrance due to its incorrect assumption regarding its theoretical null distribution. This study proposes a method for improving the accuracy of person‐fit analysis using lz which takes into account test unreliability when estimating the ability and constructs the distribution for each lz through resampling methods. The Type I error and power (or detection rate) of the proposed method were examined at different test lengths, ability levels, and nominal α levels along with other methods, and power to detect three types of aberrance—cheating, lack of motivation, and speeding—was considered. Results indicate that the proposed method is a viable and promising approach. It has Type I error rates close to the nominal value for most ability levels and reasonably good power.
Geography and American History
Authors: Patton Donald J.
Published: May 2008

Book reviewed in this article:

THE HISTORICAL GEOGRAPHY OF THE UNITED STATES. By Ralph H. Brown
Cartography and the Face of the Earth
Authors: Cameron Stewart
Published: May 2008

MAP AND LANDSCAPE. By Dorothy Sylvester.

MAPS AND DIAGRAMS. By F. J. Monkhouse and H. R. Wilkinson.

THE LOOK OF MAPS. By Arthur H. Robinson.

ELEMENTS OF CARTOGRAPHY. By Arthur H. Robinson.

GEOGRAPHY FROM THE AIR. By F. Walker.

OUR WORLD FROM THE AIR. By E. A. Gutkind. London: Chatto and Windus, 1952, pp. 250.
In New Zealand Journals…: Farming in Taranaki
Authors: Johnston W. B.
Published: May 2008

FARMING IN NEW ZEALAND: TARANAKI: A. C. Burgess
In Oversea Journals…: Continental Drift and Biogeography
Authors: Chapman V. J.
Published: May 2008

THE BIOGEOGRAPHY OF AUSTRALIA: Ronald Good
WEST WIND, EAST WIND*
Authors: BUCHANAN KEITH
Published: May 2008

Nous sommes passés, en trente amiées ponctuées de catastrophes, d'un type d'organisation du monde à un autre type que définit surtout la primauté géographique absolue des États et des frontières.—M. le Lannou
The English Colony in New South Wales: A.D. 1803*
Authors: WALSH G. P. , Collins David
Published: May 2008

‘The spot chosen for [the settlement] was at the head of a cove, near the run of fresh water, which stole silently along through a very thick wood, the stillness of which had then, for the first time since the creation, been interrupted by the rude sound of the labourer's axe, and the downfall of its ancient inhabitants;—a stillness and tranquillity which from that day were to give place to the voice of labour, the confusion of camps and towns, and ‘the busy hum of its new possessors”.’
REVIEWS
Authors: JOHNSTON W. B.
Published: May 2008

Book reviewed in this article:

GEOGRAPHY, ITS SCOPE AND SPIRIT. By J. O. M. Broek

GEOGRAPHY AS HUMAN ECOLOGY: METHODOLOGY BY EXAMPLE. Edited by S. R. Eyre and G. R. J. Jones

A PREFACE TO ECONOMIC GEOGRAPHY. By H. H. McCarty and J. B. Lindberg

A PROLOGUE TO POPULATION GEOGRAPHY. By W. Zelinsky
Urbanisation the Evolution of an Austrialian Capital
Authors: JOHNSTON R. J.
Published: May 2008

URBANISATION: THE EVOLUTION OF AN AUSTRALIAN CAPITAL.
Age sex Selectivity in Migration: Evidence for New Zealand 1966‐71
Authors: HEENAN L D. B.
Published: May 2008

Department of Geography, University of Otago, Dunedin.
Immigrant and locally bom Pacific Island Polynesians: Two populations?
Authors: Bedford Richard
Published: May 2008

At a huihuinga organised during the Conference on Pacific Studies at the University of Auckland in August 1985, there was a spirited exchange of views among participants on residence of Pacific Island Polynesians in New Zealand. As part of a wider critique of Pakeha cultural hegemony and superiority several Maori speakers stressed that Pacific Island Polynesians were manuhiri (visitors) in New Zealand and, like most of the people of European descent, they had “overstayed their permits” in the eyes of the tangata whenua. In responding to these claims, speakers from Samoa and Fiji sought to dispell a myth, still widely held in New Zealand, that the great majority of resident Pacific Island Polynesians were born in the islands. They reminded participants at the Auckland Conference that almost half of the people classed on the basis of ethnicity as Pacific Islanders in the 1981 census had been born in New Zealand. They were not “immigrants”.
Matching New Zealand Rural Development Policy to a Changing Clientele
Authors: POMEROY ANN
Published: May 2008

In responding to the needs of a broader rural clientele, MAF's rural economic development work has moved beyond a single sector approach to one which recognises all rural economic activity. New Zealand's approach to rural economic development lags behind those of most OECD countries. An official rural development policy, sponsored by MAF, is needed to ensure that there is adequate co‐ordination with other agencies' activities, and that government works in partnership with rural people to ensure their goals are realised.
Pluriactivity in (and beyond?) a Regulationist Crisis
Authors: COOMBES BRAD , CAMPBELL HUGH
Published: May 2008

The study of rural pluriactivity in New Zealand has been based on the assumption that it is a temporary phenomenon: a survival strategy in times of crisis. This paper seeks to position both pluriactivity and ‘rural crisis’ in a more sound theoretical framework by referring to recent work in regulation theory. Case studies from the Mid‐Canterbury and Catlins areas are used to suggest the role that pluriactivity may fulfil in any future mode of growth in rural New Zealand. In doing so, questions are raised regarding rural ideology and agency in the process of economic change.
Rural Women's Self‐concepts and Aspirations as Members of Selected Voluntary Organisations in New Zealand, Australia and Canada
Authors: KTEATHER ELIZABETH
Published: May 2008

Evidence from questionnaires completed by members of five rural women's organisations in 1994 and 1995 (three traditional and two younger organisations) clarifies the motives women have, and the identities they assume, in joining these organisations. The older organisations attract women who wish to make a commitment to their community but newer organisations attract women who see themselves as farmers, or as employees and professionals in the agricultural industry. This represents a major shift in gender dimensions of rurality that has taken place during the last twenty years or so. It indicates a ‘mobilisation’ of rural and farm women who seek to participate fully ‐ in their productive role and in the public sphere ‐ in the attempt to maintain the viability of family farms and rural communities. The role that organisations for men and women play in constituting the meaning of gender is discussed.
Population Dynamics and Settlement Systems
Authors: CHALMERS LEX , JOSEPH ALUN
Published: May 2008

The paper uses five broad classes of settlement in the Waikato as a base for exploring age and gender specific changes to population distributions. The trends are assessed over the period 1981 to 1991, an era of significant change to the economic and social fabric of the region. Links between this change and the inferred patterns of movement are suggested. Notable patterns include migration deficits in the youthful and elderly age classes in sparsely settled rural areas, and more substantial numbers of elderly in other non metropolitan settlements than expected. The policy implications of these distributions are considered in the concluding section of the paper.
Will the ‘Real’ Samoans Please Stand Up? Issues in Diasporic Samoan Identity
Authors: MACPHERSON CLUNY
Published: May 2008

This paper examines the circumstances in which ethnic labels and identities are constructed and the conditions that are producing socio‐cultural divergence within them. Using Samoan identities as an example, it is argued firstly that categories based on descent will not necessarily reflect socio‐cultural realities within them and, secondly, that Samoan identities constructed at various times for particular purposes may have given an impression of ethnic unity which masked considerable internal divergence. Finally, it is argued that it may be increasingly difficult for migrant Samoans to agree on symbols of Samoan identity, much less to agree on whether or not these might be building blocks of a national identity. This fluid reality raises fundamental issues about the significance of the apparently fixed descent categories with which we all routinely work.
Implications of a Century of Anthropogenic Erosion for Future Land Use in the Gisborne‐East Coast Region of New Zealand
Authors: PAGE MIKE , TRUSTRUM NOEL , GOMEZ BASIL
Published: May 2008

The East Coast of the North Island of New Zealand is world renowned for its severe erosion, flooding, and sedimentation. Extensive deforestation between 1880–1920 initiated this period of dramatic landscape transformation, and today reforestation is seen as the panacea. However, a century of pastoral farming has left a legacy of a highly degraded landscape, which is currently redistributing the products of this erosion. The rate and level of landscape recovery will influence the ability of communities to carry out future land use.

This paper uses the results of a decade of geomorphic research into the controls and processes of landscape change to illustrate some of the likely future impacts on the landscape and its land use, and to identify some still unanswered questions. This increasing understanding, together with changing community attitudes, provides the opportunity to maximise the benefits of reforestation and other management interventions.
Landscape Change and Environmental Histories
Authors: PAWSON ERIC , BROOKING TOM
Published: May 2008

Historical geography was once a popular element of university curricula in New Zealand. It was also a conspicuous focus of research. Today however there is only one identifiable course in historical geography in New Zealand's university calendars – at Massey – and few writers have maintained an active research interest rooted in the sub‐discipline. This Comment suggests some reasons why now is a good time for New Zealand's geographers to reassess this state of affairs, and outlines five themes that might be pursued in the construction of more explicit historical geographies at the start of the third millennium.
Negotiating Technology — (Re)considering the Use of GIS by Indigenous Peoples
Authors: ENGLE STEPHEN T.
Published: May 2008

Geographic Information Systems (GIS) have been increasingly touted for their ability to help empower indigenous peoples. The opportunity to discuss the development of an iwi‐based GIS with Te Ruunanga O Raukawa provides a platform for reflecting critically on issues that impact the effective use of GIS by indigenous groups. The dialectical context of GIS is explored by (re)considering the opportunities and challenges of applying GIS as a cross‐cultural communication device. A position is negotiated which interprets GIS as conditionally empowering provided that indigenous peoples consider their symbolic representation in, and physical access to GIS before making an initial investment in the technology.
Soldier Settlement in New Zealand After World War I: Two Case Studies
Authors: ROCHE MICHAEL
Published: May 2008

Historians and geographers have variously explored the WWI discharged soldier settlement schemes in New Zealand. The shared orthodoxy has emphasised the widespread failure of many of these soldier settlers and settlements. Recently there have been signs of a revisionist interpretation of the scheme. This paper extends this critique by considering the meanings of failure and success in broader terms through two New Zealand case studies. The discussion suggests that there were subtle graduations of both administrative and settler success and failure.
A Mâori Sense of Place? ‐ Taranaki Waiata Tangi and Feelings for Place
Authors: Smith Ailsa
Published: May 2008

Mâori attachment to ancestral lands may be viewed in terms of the western concept of sense of place. However, there are certain features of this attachment that require an extension of that idea to include features which are peculiar to Mâori interpretations of land and space. These features include whakapapa, whanaungatanga and ‘uri’‐tanga (generational and familial linkages), wairuatanga and atuatanga (the spiritual dimension relating to godlike ancestors and the unlocking of environmental and human potential), and tûrangawaewae and kaitiakitanga (inherited rights and obligations associated with belonging to a place that claims those with Mâori ancestry by virtue of all the above). This paper draws on data from research into Taranaki waiata tangi and feelings for place in order to discuss features relative to Mâori attitudes to land.
Adolescents’ Sexually Transmitted Disease Protective Attitudes Predict Sexually Transmitted Disease Acquisition in Early Adulthood
Authors: Crosby Richard A. , Danner Fred
Published: May 2008

Background:  Estimates suggest that about 48% of nearly 19 million cases of sexually transmitted diseases (STDs) occurring annually in the United States are acquired by persons aged 15‐24 years. The purpose of this study was to test the hypothesis that adolescents’ attitudes about protecting themselves from STDs predict their laboratory‐confirmed prevalence of STDs in early adulthood.

Methods:  Wave 3 of the National Longitudinal Study of Adolescent Health assessed Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis. This wave 3 data were regressed on data collected in wave 1 (when those followed were teens). A single‐item measure (with a 5‐point response option) assessed adolescents’ attitude: “It would be a big hassle to do the things necessary to completely protect yourself from getting an STD.”

Results:  Valid urine specimens were provided by 8297 adolescents who also completed the self‐reported measures needed for this study. Overall, 6.4% of the weighted sample tested positive for at least 1 of the 3 STDs. Controlling for age, gender, minority status, and age of sexual debut (all of which are well‐established predictors of STD prevalence), attitude toward STD protection achieved significance (P < .001). Each additional point on the 5‐point scale increased adolescents’ odds of testing positive for an STD in early adulthood by about 13%. Of interest, the attitudinal measure did not interact with any of the other variables.

Conclusions:  Findings provide evidence suggesting that safer sex programs may benefit adolescents by fostering positive attitudes toward practices that avert STD acquisition.
Sensory Experience and Intentionalism
Authors: Le Morvan Pierre
Published: May 2008

Increasingly prominent in the recent literature on the philosophy of perception, Intentionalism holds that sensory experience is inherently intentional, where to be intentional is to be about, or directed on, something. This article explores Intentionalism's prospects as a viable ontological and epistemological alternative to the traditional trinity of theories of sensory experience: the Sense‐Datum Theory, the Adverbial Theory, and the Theory of Appearing.
Comparison of Macroinvertebrate‐Derived Stream Quality Metrics Between Snag and Riffle Habitats1
Authors: Stepenuck Kristine F. , Crunkilton Ronald L. , Bozek Michael A. , Wang Lizhu
Published: May 2008

Abstract:  We compared benthic macroinvertebrate assemblage structure at snag and riffle habitats in 43 Wisconsin streams across a range of watershed urbanization using a variety of stream quality metrics. Discriminant analysis indicated that dominant taxa at riffles and snags differed; Hydropsychid caddisflies (Hydropsyche betteni and Cheumatopsyche spp.) and elmid beetles (Optioservus spp. and Stenemlis spp.) typified riffles, whereas isopods (Asellus intermedius) and amphipods (Hyalella azteca and Gammarus pseudolimnaeus) predominated in snags. Analysis of covariance indicated that samples from snag and riffle habitats differed significantly in their response to the urbanization gradient for the Hilsenhoff biotic index (BI), Shannon’s diversity index, and percent of filterers, shredders, and pollution intolerant Ephemeroptera, Plecoptera, and Trichoptera (EPT) at each stream site (p ≤ 0.10). These differences suggest that although macroinvertebrate assemblages present in either habitat type are sensitive to detecting the effects of urbanization, metrics derived from different habitats should not be intermixed when assessing stream quality through biomonitoring. This can be a limitation to resource managers who wish to compare water quality among streams where the same habitat type is not available at all stream locations, or where a specific habitat type (i.e., a riffle) is required to determine a metric value (i.e., BI). To account for differences in stream quality at sites lacking riffle habitat, snag‐derived metric values can be adjusted based on those obtained from riffles that have been exposed to the same level of urbanization. Comparison of nonlinear regression equations that related stream quality metric values from the two habitat types to percent watershed urbanization indicated that snag habitats had on average 30.2 fewer percent EPT individuals, a lower diversity index value than riffles, and a BI value of 0.29 greater than riffles.
Application of universally amplifying plastid primers to environmental sampling of a stream periphyton community
Authors: SHERWOOD ALISON R. , CHAN YVONNE L. , PRESTING GERNOT G.
Published: May 2008

To demonstrate the utility of universal plastid primers for probing of environmental samples, we extracted DNA from a tropical stream periphyton community and created two environmental clone libraries. We demonstrate the recovery of DNA sequences corresponding to the major groups of algae observed microscopically in the sample, illustrating the utility of these primers for analysis of environmental samples. Using a touchdown polymerase chain reaction technique, almost 99% of recovered sequences correspond to plastid‐containing or cyanobacterial taxa, which allows algae to be targeted to the almost complete exclusion of noncyanobacterial prokaryotes and nonplastid‐containing eukaryotes.
Characterization of 13 microsatellite loci for the deep‐sea coral, Lophelia pertusa (Linnaeus 1758), from the western North Atlantic Ocean and Gulf of Mexico
Authors: MORRISON CHERYL L. , EACKLES MICHAEL S. , JOHNSON ROBIN L. , KING TIM L
Published: May 2008

A suite of 13 polymorphic tri‐ and tetranucleotide microsatellite loci were isolated from the ahermatypic deep‐sea coral, Lophelia pertusa. Among 51 individuals collected from three disjunct oceanic regions, allelic diversity ranged from six to 38 alleles and averaged 9.1 alleles per locus. Observed heterozygosity ranged from 9.1 to 96.8% and averaged 62.3% in the Gulf of Mexico population. For some loci, amplification success varied among collections, suggesting regional variation in priming site sequences. Four loci showed departures from Hardy–Weinberg equilibrium in certain collections which may reflect nonrandom mating.
Isolation and characterization of polymorphic microsatellites for the bastard sole (Microchirus azevia)
Authors: CATANESE GAETANO , CRESPO ANIELA , ZUASTI EUGENIA , PEREZ LAURA , FUNES VICTORIA
Published: May 2008

The bastard sole (Microchirus azevia) is a species of commercial interest in Spain. Nevertheless, little information is currently available about the genetic characteristics of wild populations. In this survey, we have developed eight new microsatellites using an enriched genome library protocol. Primers were screened on a total of 54 individuals from two wild populations (Mediterranean and Atlantic) from the south coast of Spain, revealing six to 18 alleles per locus with expected heterozygosities ranging from 0.51 to 0.94. These markers can potentially be useful tools for use in population genetic studies.
Endangering the endangered: The effects of perceived rarity on species exploitation
Authors: Hall Richard J. , Milner‐Gulland E. J. , Courchamp F.
Published: May 2008

Classifying species by threat status can result in conservation benefits such as increased protection, but can also be an incentive to hunters responding to increased consumer demand for goods perceived to be rare, and therefore valuable. Bioeconomic theory provides a framework for examining the population consequences of differing responses of consumers (demand) and hunters (supply) to perceived rarity. We present a series of illustrative case studies of how perceived rarity affects consumer behavior and hunting pressure, and use a model to explore the scenario of most conservation concern (where rarity itself fuels increased exploitation). Rarity‐fuelled demand can have two undesirable outcomes: the species may become trapped at a low population size, or escalating hunting effort may drive the species to extinction. Understanding the response of consumers and hunters to perceived rarity is vital for predicting the impact of intervention strategies that seek to minimize extinction risk.
Protein kinase CK2 modulates synaptic plasticity by modification of synaptic NMDA receptors in the hippocampus
Authors: Kimura Rie , Matsuki Norio
Published: May 2008

Synaptic plasticity is the foundation of learning and memory. The protein kinase CK2 phosphorylates many proteins related to synaptic plasticity, but whether it is directly involved in it has not been clarified. Here, we examined the role of CK2 in synaptic plasticity in hippocampal slices using the CK2 selective inhibitors 5,6‐dichloro‐1‐β‐d‐ribofuranosylbenzimidazole (DRB) and 4,5,6,7‐tetrabromobenzotriazole (TBB). These significantly inhibited N‐methyl‐d‐aspartate (NMDA) receptor‐dependent long‐term potentiation (LTP). DRB also inhibited NMDA receptor‐mediated synaptic transmission, while leaving NMDA receptor‐independent LTP unaffected. NMDA receptors thus appear to be the primary targets of CK2. Although both long‐term depression (LTD) and LTP are induced by the influx of Ca2+ through NMDA receptors, surprisingly, LTD was not affected by CK2 inhibitors. We postulated that the LTP‐selective modulation by CK2 is due to selective modulation of NMDA receptors, and tested two hypotheses concerning the modulation of NMDA receptors: (i) CK2 selectively modulates NR2A subunits possibly related to LTP, but not NR2B subunits possibly related to LTD; and (ii) CK2 selectively affects synaptic but not extrasynaptic NMDA receptors whose activation is sufficient to induce LTD. DRB decreased NMDA receptor‐mediated synaptic transmission in the presence of selective NR2A subunit antagonist. The former hypothesis thus appears unlikely to be correct. However, DRB decreased synaptic NMDA receptor responses in cultured hippocampal neurons without affecting extrasynaptic NMDA receptor current. These findings support the latter hypothesis, that CK2 selectively affects LTP by selective modification of synaptic NMDA receptors in a receptor‐location‐specific manner.
High frequency action potential bursts (≥ 100 Hz) in L2/3 and L5B thick tufted neurons in anaesthetized and awake rat primary somatosensory cortex
Authors: De Kock C. P. J. , Sakmann B.
Published: May 2008

High frequency (≥ 100 Hz) bursts of action potentials (APs) generated by neocortical neurons are thought to increase information content and, through back‐propagation, to influence synaptic integration and efficacy in distal dendritic compartments. It was recently shown in acute slice experiments that intrinsic bursting properties differ between neocortical L2/3 and L5B (thick tufted) neurons. In L2/3 neurons for instance, dendritic APs were brief and generated only one additional AP after the initial somatic AP. In L5B neurons, dendritic plateau potentials facilitated the generation of trains of three or more APs. We recently showed in vivo that spiking frequencies are very different for L2/3 and L5B thick tufted neurons under anaesthesia. Here, we addressed the question whether in vivo the bursting properties are different for these two cell types. We recorded from L2/3 and L5B thick tufted neurons of rat primary somatosensory (barrel) cortex under anaesthetized and awake conditions and found that AP activity is dominated by single APs. In addition, we found that in the anaesthetized animal also bursts of two APs were observed in L2/3 neurons but the relative occurrence of these bursts was low. In L5B thick tufted neurons, bursts consisting of up to six APs were recorded and their relative occurrence was significantly higher. Frequencies within bursts were also significantly higher in L5B thick tufted neurons than in L2/3 neurons. In awake (head‐restrained) animals, average spike frequencies of L2/3 and L5B thick tufted neurons were surprisingly similar to spike rates under anaesthesia. However, bursting behaviour in L2/3 neurons was comparable to L5B thick tufted neurons. Thus, the distribution of interspike intervals was changed in L2/3 neurons without affecting the average spiking rate. We observed bursts consisting of up to five APs in both cell types and both probability of bursts and AP frequency within bursts were similar for L2/3 and L5B thick tufted neurons. Our analysis shows that most cortical APs occur as single APs, although a minor fraction of APs in L2/3 and L5B thick tufted neurons are part of high frequency bursts (15%). This AP bursting is dependent on the behavioural state of the animal in a cell‐type dependent manner.
Integrating Compact Thermal Models in CFD Simulations of Electronic Packages
Authors: Gupta Rohit Dev , Eswaran Vinayak
Published: May 2008

Compact thermal models (CTMs) are simplified multi-nodal thermal resistor network representations of the detailed material and geometric structure of the electronic package. CTMs predict the thermal response of the package, in various environments, to within an accuracy of 2%. The junction temperature of the package is typically obtained by solving the linear algebraic network equations of the CTM, with the heat transfer to the ambience modeled by a convection coefficient obtained from handbooks, assuming identical ambient conditions imposed on all nodal surfaces. This approach may give misleading results as the ambience at each nodal surface can differ depending on the cooling flow patterns at that surface. In this work, a methodology is presented where the network equations of the CTM are integrated into the governing fluid flow and energy equations solved by computational fluid dynamics (CFD). The CTM+CFD approach predicts a significantly (20–30%) higher junction temperature as compared to the conventional CTM network solver method, even when the convection coefficient used in the latter case is obtained more accurately from CFD, rather than from handbook correlations. It is also found that CFD computations assuming uniform flux at the package surfaces (and ignoring the internal resistance of the package) vastly under-predict the junction temperature. The new approach offers a promising alternative for electronic package thermal design and is highly advantageous where the internal geometric and material configurations are not known due to proprietary concerns.
A Deconvolution-Based Approach to Structural Dynamics System Identification and Response Prediction
Authors: Allison Timothy C. , Miller A. Keith , Inman Daniel J.
Published: May 2008

Two general linear time-varying system identification methods for multiple-input multiple-output systems are proposed based on the proper orthogonal decomposition (POD). The method applies the POD to express response data for linear or nonlinear systems as a modal sum of proper orthogonal modes and proper orthogonal coordinates (POCs). Drawing upon mode summation theory, an analytical expression for the POCs is developed, and two deconvolution-based methods are devised for modifying them to predict the response of the system to new loads. The first method accomplishes the identification with a single-load-response data set, but its applicability is limited to lightly damped systems with a mass matrix proportional to the identity matrix. The second method uses multiple-load-response data sets to overcome these limitations. The methods are applied to construct predictive models for linear and nonlinear beam examples without using prior knowledge of a system model. The method is also applied to a linear experiment to demonstrate a potential experimental setup and the method’s feasibility in the presence of noise. The results demonstrate that while the first method only requires a single set of load-response data, it is less accurate than the multiple-load method for most systems. Although the methods are able to reconstruct the original data sets accurately even for nonlinear systems, the results also demonstrate that a linear time-varying method cannot predict nonlinear phenomena that are not present in the original signals.
Application of a Novel Hybrid Intelligent Method to Compound Fault Diagnosis of Locomotive Roller Bearings
Authors: Lei Yaguo , He Zhengjia , Zi Yanyang
Published: May 2008

To diagnose compound faults of locomotive roller bearings accurately, a novel hybrid intelligent diagnosis method is proposed in this paper. First of all, vibration signals are preprocessed to mine valid fault characteristic information. They are filtered and at the same time, they are decomposed by the empirical mode decomposition method and eight intrinsic mode functions (IMFs) are acquired. The filtered signals and IMFs are further demodulated to obtain their Hilbert envelope spectrums. Second, six feature sets are extracted, and they are time- and frequency-domain statistical features of the raw and preprocessed signals. Then, each feature set is evaluated and a few salient features are selected from it by applying the improved distance evaluation technique. Correspondingly, six salient feature sets are obtained. Finally, the six salient feature sets are, respectively, input into six classifiers based on adaptive neurofuzzy inference system (ANFIS), and genetic algorithm is employed to combine the outputs of the six ANFISs and to attain the final diagnosis result. The diagnosis results of the compound faults of the locomotive roller bearings verify that the proposed hybrid intelligent method may accurately recognize not only a single fault and fault severities but also compound faults.
Probability Distribution of Peaks for Nonlinear Combination of Vector Gaussian Loads
Authors: Gupta Sayan , van Gelder P. H. A. J. M.
Published: May 2008

The problem of approximating the probability distribution of peaks, associated with a special class of non-Gaussian random processes, is considered. The non-Gaussian processes are obtained as nonlinear combinations of a vector of mutually correlated, stationary, Gaussian random processes. The Von Mises stress in a linear vibrating structure under stationary Gaussian loadings is a typical example for such processes. The crux of the formulation lies in developing analytical approximations for the joint probability density function of the non-Gaussian process and its instantaneous first and second time derivatives. Depending on the nature of the problem, this requires the evaluation of a multidimensional integration across a possibly irregular and disjointed domain. A numerical algorithm, based on first order reliability method, is developed to evaluate these integrals. The approximations for the peak distributions have applications in predicting the expected fatigue damage due to combination of stress resultants in a randomly vibrating structure. The proposed method is illustrated through two numerical examples and its accuracy is examined with respect to estimates from full scale Monte Carlo simulations of the non-Gaussian process.
Forced Oscillations of a Continuous Asymmetrical Rotor With Geometric Nonlinearity (Major Critical Speed and Secondary Critical Speed)
Authors: Nagasaka Imao , Ishida Yukio , Liu Jun
Published: May 2008

Forced oscillations in the vicinities of both the major and the secondary critical speeds of a continuous asymmetrical rotor with the geometric nonlinearity are discussed. When the self-aligning double-row ball bearings support the slender flexible rotor at both ends, the geometric nonlinearity appears due to the stiffening effect in elongation of the shaft if the movements of the bearings in the longitudinal direction are restricted. The nonlinearity is symmetric when the rotor is supported vertically, and is asymmetric when it is supported horizontally. Because the rotor is slender, the natural frequency pfn of a forward whirling mode and pbn of a backward whirling mode have the relation of internal resonance pfn:pbn=1:(−1). Due to the influence of the internal resonance, various phenomena occur, such as Hopf bifurcation, an almost periodic motion, the appearance of new branches, and the diminish of unstable region. These phenomena were clarified theoretically and experimentally. Moreover, this paper focuses on the influences of the nonlinearity, the unbalance, the damping, and the lateral force on the vibration characteristics.
Thermal Conduction Switch for Thermal Management of Chip Scale Atomic Clocks (IMECE2006-14540)
Authors: Laws A. D. , Chang Y. J. , Bright V. M. , Lee Y. C.
Published: May 2008

We report the first use of a bimetallic buckling disk as a thermal conduction switch. The disk is used to passively alter the thermal resistance of the package of a chip scale atomic clock. A vertical-cavity surface-emitting laser and a cesium vapor cell, contained in the clock, must be maintained at 70±0.1°C even under an ambient temperature variation of −40°Cto50°C. A thermal test vehicle has been developed to characterize a sample package with a thermal conduction switch. Three cases are presented for the temperature control of the test vehicle under different load placements and environmental conditions: (1) a heating load with a good conduction path to the switch in a vacuum package; (2) the same loading as in Case 1, but packaged in air; and (3) a heating load insulated from the switch, in a vacuum package. At 38°C, the switch snaps upward to reduce the package’s thermal resistance. As a result, the heating power needed to maintain a constant temperature, 63.9±0.1°C, is increased from 118to200mW for Case 1. Such a significant change of the thermal resistance demonstrates the effectiveness of the thermal switch. However, the switch becomes less effective with air filling the gap, as in Case 2, and the switch is not effective at all if the heating load does not have a good conduction path to the switch as in Case 3. The steady state response of this novel thermal conduction switch has been well characterized through experimentation and finite element analysis.
Board Level Drop Test Analysis Based on Modal Test and Simulation
Authors: Liu Fang , Meng Guang , Zhao Mei , Zhao Junfeng
Published: May 2008

Solder joint reliability in drop test is crucial for handheld systems, such as mobile phone, digital camera, and MP3 player. In recent years, a lot of experiments and simulations have been carried out by researchers to study board level drop test, and many useful results have been obtained. Regarding mechanical simulation and analysis, there are still two challenges: How to design drop test printed circuit board (PCB) based on dynamic simulation and analysis? How to get accurate elastic modulus of PCB, especially damping parameters, as property inputs for drop test simulation? In this study, an approach based on systematic modal tests and analyses is used to address these two challenges. First, modal dynamic simulation is used to design the test board to meet drop test requirements. Second, modal tests are conducted on drop test board in order to validate dynamic simulation and measure structural damping parameters and overall board elastic modulus as well. Adopted directly in drop test simulation, the measured damping parameters and elastic modulus are proved to be accurate. It is verified through comparison between the finite element simulation and real drop test results. With the modal tests and simulation method established here, drop simulation becomes very simple and accurate, and test board design and characterization are also simplified. Thus, considerable drop test experiment and simulation fine tune, and validation work can be saved.
Thermal Resistance of Particle Laden Polymeric Thermal Interface Materials
Authors: Prasher Ravi S. , Shipley Jim , Prstic Suzana , Koning Paul , Wang Jin-Lin
Published: May 2008

Particle laden polymers are one of the most prominent thermal interface materials (TIM) used in electronics cooling. Most of the research has primarily dealt with the understanding of the thermal conductivity of these types of TIMs. For thermal design, reduction of the thermal resistance is the end goal. Thermal resistance is not only dependent on the thermal conductivity, but also on the bond line thickness (BLT) of these TIMs. It is not clear which material property(s) of these particle laden TIMs affects the BLT and eventually the thermal resistance. This paper introduces a rheology based semi-empirical model for the prediction of the BLT of these TIMs. BLT depends on the yield stress of the particle laden polymer and the applied pressure. The BLT model combined with the thermal conductivity model can be used for modeling the thermal resistance of these TIMs for factors such as particle volume faction, particle shape, base polymer viscosity, etc. This paper shows that there exists an optimal filler volume fraction at which thermal resistance is minimum. Finally this paper develops design rules for the optimization of thermal resistance for particle laden TIMs.
A Genetic Algorithm Approach to Weld Pattern Optimization in Sheet Metal Assembly
Authors: Liao Gene Y.
Published: May 2008

In sheet metal assembly process, welding operation joins two or more sheet metal parts together. Since sheet metals are subject to dimensional variation resulted from manufacturing randomness, gap may be generated at each weld pair prior to welding. These gaps are forced to close during a welding operation and accordingly undesirable structural deformation results. Optimizing the welding pattern (the number and locations of weld pairs) of an assembly process was proven to significantly improve the quality of final assembly. This paper presents a Genetic Algorithm (GA)-based optimization method to automatically search for the optimal weld pattern so that the assembly deformation is minimized. Application result of a real industrial part demonstrated that the proposed algorithm effectively achieve the objective.
Application of Systems Modeling and Simulation in the Discrete Ratio Automatic Transmission Calibration Process for an Automobile
Authors: King Graham S. , Jones R. Peter , Bailey Andrew D.
Published: May 2008

This paper describes the application of systems modeling and simulation to the process of calibrating shift schedules for an automatic discrete ratio transmission in an automobile. A simulation tool capable of predicting the effect of transmission calibration changes on vehicle performance, fuel economy, and shift consistency and busyness is presented. The simulation tool includes a powertrain system model in which the physically based elements were developed using Modelica/Dymola and the functionality of the electronic transmission controller was realized using MATLAB/Stateflow. The complete powertrain system model is simulated in the MATLAB/Simulink environment and has been validated against data obtained from vehicle tests. The simulation tool also incorporates a graphical user interface to facilitate its use by calibration engineers as an integral part of the transmission calibration process: The paper discusses the role of the simulation tool during two phases of the calibration process: the initial design of shift schedules; and in-vehicle development of shift schedules. The results of a back-to-back comparison between the traditional, experimentally based transmission calibration process and a revised process, centered on use of the simulation tool, demonstrate that applying the simulation tool as an integral part of the calibration process can save a significant amount of calibration engineers and vehicle testing time.
Forced Convection Flow Through an Unsaturated Wellbore
Authors: Martins-Costa Maria Laura , Saldanha da Gama Roge´rio M.
Published: May 2008

This work studies the dynamics of the filling up of a rigid cylindrical shell porous matrix by a Newtonian fluid and the heat transfer associated phenomenon. A mixture theory approach is employed to obtain a preliminary local model for nonisothermal flows through a wellbore. The mixture consists of three overlapping continuous constituents: a solid (porous medium), a liquid and an inert gas included to account for the compressibility of the mixture as a whole. Assuming the convection flow on radial direction only, a set of four nonlinear partial differential equations describes the problem. Its hydrodynamic part — a nonlinear hyperbolic system — is approximated by means of a Glimm’s scheme, combined with an operator splitting technique, while an implicit finite difference scheme is used to simulate the thermal part.
Studies of Hydrogen Embrittlement Effects on Steel Pipeline Used for Natural Gas Transport
Authors: Al-Obaid Y. Y. , Al-Obaid Y. F.
Published: May 2008

A steel pipeline containing niobium, vanadium and titanium as microalloying elements was tested for hydrogen embrittlement. Hydrogenated specimens intercritically annealed at relatively low temperature to develop martensite islands in a ferrite matrix basically exhibited quasi-cleavage fracture with some ductile dimpling. The objective of this investigation, carried out by the principal investigator is to study the mechanical properties and susceptibility to hydrogen embrittlement effects on steel pipeline used for natural gas transport.
Experimental Measurements and Computational Solutions for Aerodynamic Forces on an Ahmed Body at Various Ground Clearances
Authors: Bayraktar Ilhan , Landman Drew , Bayraktar Tuba
Published: May 2008

Reliable computer solutions to external aerodynamic flow fields on road vehicles are extremely desirable to road vehicle designers. In a previous publication a study was performed to validate a Reynolds-averaged unsteady Navier-stokes solution for the aerodynamic characterization of a large-scale bluff body. In the present study, the external aerodynamics of this body as a function of ground clearance are explored. Experimental force measurements are obtained in a full-scale wind tunnel using an Ahmed body model and test conditions representative of full-scale operating conditions. A Reynolds averaged Navier-Stokes solver is employed for computational simulation of the external flowfield at the same conditions. Experimental and computational force coefficients versus vehicle ground clearance are presented for fixed ground, moving ground, and suction slot road simulations. Experimental results using boundary layer suction are compared to computational results with a moving ground plane in order to better understand the effect of a road simulation method.
Manufacturing Structures in Nanometer Scale by Nanomanipulation
Authors: Zhang Y. J. , Hu Y. Z. , Wang H. , Li P. , Huang L.
Published: May 2008

Nanomanipulation based on atomic force microscope is one of the key technologies for nanomanufacturing. It plays important role in practical fabrication of nanodevices. In this paper, nanomanipulation method is used to build a structure in nanometer scale. A basic pattern made up of single-wall carbon nanotube on silicon substrate was successfully obtained by sophisticated manipulations, and thus provides an effective way to make more complicated nanostructures. In the meantime, experiments results also show a promising prospect to build future nanodevices step by step using this technique. Carbon nanotubes are selected as the raw materials for nanofabrication due to their excellent mechanical and electrical properties, which are the most suitable for the application in building nano-electromechanical systems (NEMS). In addition, the major failure modes of nanomanipulation experiments were also analyzed by FED-SEM observation. The main factors affecting the final manipulation results, wear and pollution of tips, and their corresponding relations between tips and experiment results were analyzed. Furthermore, the preventive measurements were proposed in order to get better results. A new method for measuring manipulating forces was explored in the experiments based on a commercial AFM (Atom Force Microscope). Lateral forces while manipulating and cutting a single-walled carbon nanotube was successfully measured that providing valuable information for quantitative research on nanomechanics.