bluuebunny/crossref_metadata_2025 huggingface dataset:
The Smithers’ view: a rocky road ahead for Japan and the USA
Authors: Bruce Robert
Published: October 2002

Andrew Smithers is a leading UK economist and pundit. This outline of a talk which he gave to the UK Asset and Liability Management Association earlier this year looks at the economic prognosis for both the Japanese and the US economies. Both are facing tough and almost impossible choices, he thought. The world economy was unlikely to come through unscathed.
Insurance companies: waking up to international standards
Authors: Masters Nigel , Dupont Eric
Published: October 2002

International Accounting Standards are steadily becoming the norm. The European Union agreement that all listed companies in Europe must comply by the year 2005 has hastened the process further. This brings particular challenges for all organisations in the financial services world but for insurance companies in particular. The authors assess what changes will be required in insurance company reporting and lay particular stress on risk management.
Reflective Internet searching: an action research model
Authors: Lauretta Edwards Sylvia , Bruce Christine
Published: October 2002

Sources of information and other opportunities available via the Internet are increasing exponentially. This comes with the steady increase in Internet use for education, marketing and commercial trading, and in government for communication of information to citizens. Using the action research cycle of planning, acting, recording and reflecting, this article introduces a model for an approach to Internet searching and use. The model is a conceptual framework for Internet searching that will help people to overcome the challenges of working within an environment that is subject to continuous change, both in the forms of technology used and in the content that is available through the Internet. Our model encourages the searcher to use action research principles to enlighten their searching, reflecting and learning about new techniques as the tools that they use change around them. Our model should prove valuable to educators, researchers and consultants to inform their own practice as well as for use in the educational environment.
Potential points of brand leverage: consumers’ emergent attributes
Authors: Bristol Terry
Published: October 2002

This paper presents a conceptualization of brand extension attributes that emerge when consumers evaluate brand extensions. These emergent attributes are unique in the extension product category and thus represent potential points of leverage for the brand. An empirical study was conducted to show the utility of these attributes in influencing consumers’ responses. Consumers were allowed to write their thoughts as they evaluated fictitious extensions of four actual brands. The results indicate that when emergent attributes are formed, they appear to influence consumers’ attitudes toward brand extensions. Unlike previous findings that have suggested that good fit is necessary to ensure extension success, the results indicate that the influence of emergent attributes on consumer attitudes increases as the brand’s fit with the extension decreases.
Brand choice in gift‐giving: recipient influence
Authors: Parsons Andrew G.
Published: October 2002

This research examines the impact of intended recipient on brand choice when purchasing a gift. Keller’s conceptualisation of consumer‐based brand equity, incorporating symbolic, experiential, and functional benefits, is used as a branding framework in combination with Belk’s characteristics of gifts, for measuring consumer behaviour differences occurring in alternative gift‐giving situations. The influence of gender, household income, and age are also examined. Findings suggest consumers vary in their choice of brands for different recipient groups. They also suggest that there are gender‐based differences in consumer’s brand choice for gifts, along with some income and age related distinctions. Finally, the findings suggest that overall consumers tend to look for brands with greater perceived symbolic benefits when purchasing gifts. Implications for the gift industry are offered along with future research possibilities.
A framework for the selection of electronic marketplaces: a content analysis approach
Authors: Stockdale Rosemary , Standing Craig
Published: October 2002

Although there has recently been an increased practitioner and media focus on electronic marketplaces, there still remains confusion over the advantages of participation. As a consequence organisations are finding difficulty in developing strategies, policies and procedures in relation to the e‐marketplace selection process. In some cases due to the dynamic and evolving environment of electronic trading, there can be a reluctance on the part of buyers and suppliers to participate in e‐marketplaces. Several classification models offer assessments of which type of marketplace are most suitable for different procurement purposes, but they fail to remain relevant in this dynamically changing environment. In this paper a content analysis of research and practitioner articles is carried out to evaluate the issues that prospective participants, seeking to purchase goods and services online, need to address in their selection process. A framework to support electronic marketplace related decision making is proposed, which is based within the contexts of business drivers, internal company issues and e‐marketplace facilitators.
Online kiosks: the alternative to mobile technologies for mobile users
Authors: Slack Frances , Rowley Jennifer
Published: October 2002

Online kiosks have the potential to be a significant alternative to mobile technologies in retailing, information provision and service delivery. This article describes the development and use of different types of online kiosk in contexts where users are on the move and away from fixed technologies. A case study of a major UK airport terminal is used to illustrate different types of kiosk applications. Comparisons are made with mobile phone technologies. Online kiosks have a niche in allowing access to information, services and e‐commerce technologies for all potential consumers. However, they also have a much wider role in self‐managed, self‐service delivery of information, services, goods and relationships to consumers on the move.
In search of GSS impact on groups: an exploratory field study
Authors: Martz Ben
Published: October 2002

The fundamental goal of a group support system (GSS) is to support the work performed by groups and teams. More often than not, the projects undertaken by groups and teams occur over a period of time longer than a single meeting. However, the lack of longitudinal studies is a concern that has been highlighted in meta‐analyses of GSS research. For example, little is known in regard to the GSS impacts on group member behavior in traditional meetings after their exposure to GSSs. This field study looks at a single work group using a GSS to complete an organizational restructure over a period of ten weeks. The goal is to observe the impact of changes in two sets of groupware‐team member characteristics: the perceptions of groupware over time and the impact of GSS usage on individual team member behavior in future meetings.
Public intervention in the entrepreneurial process
Authors: Inge Jenssen Jan , Anders Havnes Per
Published: October 2002

In this paper we discuss three Norwegian cases of public programmes aimed at enhancing entrepreneurship at the regional/local level. The cases provide insight into a wide range of public initiatives implemented by the authorities such as education, consultancy, and financial stimuli. The programmes have been subjected to relatively comprehensive evaluations. In these evaluations, and also in most other evaluations of public means aimed at stimulating entrepreneurs, some important questions related to the effects on business creation and on the long term social impact of the interventions still remain to be answered. In order to overcome the problems, future research should apply longitudinal and comparative studies and use unobtrusive measures. We also discuss a theoretical framework in which entrepreneurship programmes can be interpreted and applied as a tool to improve such initiatives. Central elements in this framework are the concepts of human, social and financial capital.
The implementation and impact of operations strategies in fast‐moving supply systems
Authors: Lowson Robert
Published: October 2002

This paper provides an empirical contribution to the debate concerning the implementation and impact of operations strategies. Their nature is described, as is the necessity for their adoption. Details of the possible composition of such strategies is suggested and consideration given to how they attain strategic status. The work also offers some quantitative evidence as to the possible impact of these strategies and their contribution to competitive advantage.
Beyond “loss‐of‐control”: telecommunications, surveillance, drugs and terrorism
Authors: Shields Peter
Published: October 2002

In the US (and elsewhere), law enforcement agencies take the position that new telecommunications technologies are eroding their abilities to intercept and monitor electronic communications. They argue that they are “losing control”. Without new telecommunications surveillance powers, the argument runs, drug traffickers and terrorists will be able to operate with impunity within virtual sanctuaries. The problem with this narrative is that it functions to deflect attention from the fact that the US State has contributed significantly to some of the very problems that that have generated the calls for new surveillance powers. An alternative narrative sketched. It is argued that the escalation of the US State’s failed War on Drugs has been a key factor behind the proliferation of the recent surveillance initiatives. It is suggested that a similar dynamic may be operating in the US State’s New War on Terrorism.
The impact of the Internet on the law and economics of the music industry
Authors: Meisel John B. , Sullivan Timothy S.
Published: October 2002

Business as usual in the music industry is over. Online music is a force to be reckoned with now and increasingly in the future. This paper first describes the current revenue streams and cost causers that characterize the traditional business model in the music industry. Then, the impact of the Internet on the current business model is described, especially as it relates to the distribution stage of the value chain in the record business. Also, the impact of the Internet’s disruption of the distribution stage on the state of existing copyright law, as manifested through the introduction of Napster’s peer‐to‐peer innovation, is explained. Third, an analysis of salient economic, political/legal, and technological issues arising from these changes on the entire industry is presented. Finally, the paper identifies characteristics of a viable business model in the music industry and offers lessons for other digital content industries.
Sustainability and peace in Costa Rica
Authors: Mata Segreda Alejandrina
Published: October 2002

This article describes initiatives at the University of Costa Rica, which, in combination with national programs, have strengthened the country’s commitment to sustainable development over the past 15 years. It discusses the university’s role in defining a national perspective on sustainability starting in 1987, as well as the evolution of the university’s Programa Institucional de Sostenibilidad y Paz (PRINSOPAZ) from being university focused to joining with the Earth Council to promote the Earth Charter both nationally and internationally.
Remember the human: the first rule of netiquette, librarians and the Internet
Authors: Sturges Paul
Published: October 2002

In one of the written versions of netiquette, the first rule is “remember the human”. This is intended to encourage more tolerant and considerate behaviour amongst Internet users. It could also be taken as a reminder to librarians that they should not let the attractions of new technology cause them to forget the human dimension. A major aspect of the relationship between the librarian and the user is the confidentiality of transactions and the librarian’s commitment to preserving the user’s privacy. Results from Loughborough University’s Privacy in the Digital Library project suggest that users have very strong trust that their privacy is safe with librarians. However, the results also suggest that librarians are not well organised to protect user privacy against possible intrusions from commerce, government or other sources. Other evidence suggests computer system managers do not fully share the librarian’s concern for human values, and tend to place technical considerations first, so there is a need for libraries to develop policy that emphasises human values in the technological context. The principles behind sets of guidelines on policy development drafted for the Council of Europe, the Loughborough project, and Library Association Publishing, are outlined.
An evaluation of board practices in Brazil
Authors: Leal Ricardo P.C. , De Oliveira Claudia L.T.
Published: October 2002

We survey board practices in Brazil. Brazilian companies are commonly controlled by family groups or through shareholders agreements. Controlling shareholders hold a very large portion of voting shares, much more than the minimum necessary to retain control. There is widespread evidence of shareholder expropriation, legal protection is weak, and stock issuance has been halted by low valuations and tax avoidance. Half of the boards are either too small or too big. Board committees are ineffective. Board procedures are rarely formalized and board members and CEOs are not evaluated in most cases. Most board members are not shareholders. No more than 21 percent of board members are independent and only 2 percent of them are elected by independent shareholder groups. It is likely the improvements in board structure and procedures will be restricted to large public corporations with foreign stock ownership while most companies avoid going public.
Thermodynamic environments in proteins: Fundamental determinants of fold specificity
Authors: Wrabl James O. , Larson Scott A. , Hilser Vincent J.
Published: October 2002

To investigate the relationship between an amino acid sequence and its corresponding protein fold, a database of thermodynamic stability information was assembled as a function of residue type from 81 nonhomologous proteins. This information was obtained using the COREX algorithm, which computes an ensemble‐based description of the native state of proteins. Dissection of the COREX stability constant into its fundamental energetic components resulted in 12 thermodynamic environments describing the tertiary architecture of protein folds. Because of the observation that residue types partitioned unequally between these environments, it was hypothesized that thermodynamic environments contained energetic information that connected sequence to fold. To test the significance of this hypothesis, the thermodynamic stability information was incorporated into a three‐dimensional–to–one‐dimensional scoring matrix, and simple fold recognition experiments were performed in a manner such that information about the fold target was never included in the scoring. For 60 out of 81 fold targets, the correct sequence for the target scored in the top 5% of 3858 decoy sequences, with Z‐scores ranging from 1.76 to 12.23. Furthermore, a scoring matrix assembled from the residues of 40 nonhomologous all‐α proteins was used to thread sequences against 12 nonhomologous all‐β protein targets. In 10 of 12 cases, sequences known to adopt the native all‐β structure scored in the top 5% of 3858 decoy sequences, with Z‐scores ranging from 1.99 to 7.94. These results indicate that energetic information encoded by thermodynamic environments represents a fundamental property of proteins that underlies classifications based on secondary structure.
Overcoming drug resistance in HIV‐1 chemotherapy: The binding thermodynamics of Amprenavir and TMC‐126 to wild‐type and drug‐resistant mutants of the HIV‐1 protease
Authors: Ohtaka Hiroyasu , Velázquez‐Campoy Adrian , Xie Dong , Freire Ernesto
Published: October 2002

Amprenavir is one of six protease inhibitors presently approved for clinical use in the therapeutic treatment of AIDS. Biochemical and clinical studies have shown that, unlike other inhibitors, Amprenavir is severely affected by the protease mutation I50V, located in the flap region of the enzyme. TMC‐126 is a second‐generation inhibitor, chemically related to Amprenavir, with a reported extremely low susceptibility to existing resistant mutations including I50V. In this paper, we have studied the thermodynamic and molecular origin of the response of these two inhibitors to the I50V mutation and the double active‐site mutation V82F/I84V that affects all existing clinical inhibitors. Amprenavir binds to the wild‐type HIV‐1 protease with high affinity (5.0 × 109 M−1 or 200 pM) in a process equally favored by enthalpic and entropic contributions. The mutations I50V and V82F/I84V lower the binding affinity of Amprenavir by a factor of 147 and 104, respectively. TMC‐126, on the other hand, binds to the wild‐type protease with extremely high binding affinity (2.6 × 1011 M−1 or 3.9 pM) in a process in which enthalpic contributions overpower entropic contributions by almost a factor of 4. The mutations I50V and V82F/I84V lower the binding affinity of TMC‐126 by only a factor of 16 and 11, respectively, indicating that the binding affinity of TMC‐126 to the drug‐resistant mutants is still higher than the affinity of Amprenavir to the wild‐type protease. Analysis of the data for TMC‐126 and KNI‐764, another second‐generation inhibitor, indicates that their low susceptibility to mutations is caused by their ability to compensate for the loss of interactions with the mutated target by a more favorable entropy of binding.
Crystal structures and enzymatic properties of three formyltransferases from archaea: Environmental adaptation and evolutionary relationship
Authors: Mamat Björn , Roth Annette , Grimm Clemens , Ermler Ulrich , Tziatzios Christos , Schubert Dieter , Thauer Rudolf K. , Shima Seigo
Published: October 2002

Formyltransferase catalyzes the reversible formation of formylmethanofuran from N5‐formyltetrahydromethanopterin and methanofuran, a reaction involved in the C1 metabolism of methanogenic and sulfate‐reducing archaea. The crystal structure of the homotetrameric enzyme from Methanopyrus kandleri (growth temperature optimum 98°C) has recently been solved at 1.65 Å resolution. We report here the crystal structures of the formyltransferase from Methanosarcina barkeri (growth temperature optimum 37°C) and from Archaeoglobus fulgidus (growth temperature optimum 83°C) at 1.9 Å and 2.0 Å resolution, respectively. Comparison of the structures of the three enzymes revealed very similar folds. The most striking difference found was the negative surface charge, which was −32 for the M. kandleri enzyme, only −8 for the M. barkeri enzyme, and −11 for the A. fulgidus enzyme. The hydrophobic surface fraction was 50% for the M. kandleri enzyme, 56% for the M. barkeri enzyme, and 57% for the A. fulgidus enzyme. These differences most likely reflect the adaptation of the enzyme to different cytoplasmic concentrations of potassium cyclic 2,3‐diphosphoglycerate, which are very high in M. kandleri (>1 M) and relatively low in M. barkeri and A. fulgidus. Formyltransferase is in a monomer/dimer/tetramer equilibrium that is dependent on the salt concentration. Only the dimers and tetramers are active, and only the tetramers are thermostable. The enzyme from M. kandleri is a tetramer, which is active and thermostable only at high concentrations of potassium phosphate (>1 M) or potassium cyclic 2,3‐diphosphoglycerate. Conversely, the enzyme from M. barkeri and A. fulgidus already showed these properties, activity and stability, at much lower concentrations of these strong salting‐out salts.
Mapping sequence differences between thimet oligopeptidase and neurolysin implicates key residues in substrate recognition
Authors: Ray Kallol , Hines Christina S. , Rodgers David W.
Published: October 2002

The highly homologous endopeptidases thimet oligopeptidase and neurolysin are both restricted to short peptide substrates and share many of the same cleavage sites on bioactive and synthetic peptides. They sometimes target different sites on the same peptide, however, and defining the determinants of differential recognition will help us to understand how both enzymes specifically target a wide variety of cleavage site sequences. We have mapped the positions of the 224 surface residues that differ in sequence between the two enzymes onto the surface of the neurolysin crystal structure. Although the deep active site channel accounts for about one quarter of the total surface area, only 11% of the residue differences map to this region. Four isolated sequence changes (R470/E469, R491/M490, N496/H495, and T499/R498; neurolysin residues given first) are well positioned to affect recognition of substrate peptides, and differences in cleavage site specificity can be largely rationalized on the basis of these changes. We also mapped the positions of three cysteine residues believed to be responsible for multimerization of thimet oligopeptidase, a process that inactivates the enzyme. These residues are clustered on the outside of one channel wall, where multimerization via disulfide formation is unlikely to block the substrate‐binding site. Finally, we mapped the regulatory phosphorylation site in thimet oligopeptidase to a location on the outside of the molecule well away from the active site, which indicates this modification has an indirect effect on activity.
Characterization of Herpes Simplex Virus type 1 thymidine kinase mutants engineered for improved ganciclovir or acyclovir activity
Authors: Kokoris Mark S. , Black Margaret E.
Published: October 2002

Herpes Simplex Virus type 1 (HSV‐1) thymidine kinase (TK) is currently the most widely used suicide agent for gene therapy of cancer. Tumor cells that express HSV‐1 thymidine kinase are rendered sensitive to prodrugs due to preferential phosphorylation by this enzyme. Although ganciclovir (GCV) is the prodrug of choice for use with TK, this approach is limited in part by the toxicity of this prodrug. From a random mutagenesis library, seven thymidine kinase variants containing multiple amino acid substitutions were identified on the basis of activity towards ganciclovir and acyclovir based on negative selection in Escherichia coli. Using a novel affinity chromatography column, three mutant enzymes and the wild‐type TK were purified to homogeneity and their kinetic parameters for thymidine, ganciclovir, and acyclovir determined. With ganciclovir as the substrate, one mutant (mutant SR39) demonstrated a 14‐fold decrease in Km compared to the wild‐type enzyme. The most dramatic change is displayed by mutant SR26, with a 124‐fold decrease in Km with acyclovir as the substrate. Such new “prodrug kinases” could provide benefit to ablative gene therapy by now making it feasible to use the relatively nontoxic acyclovir at nanomolar concentrations or ganciclovir at lower, less immunosuppressive doses.
Plant annexins form calcium‐independent oligomers in solution
Authors: Hofmann Andreas , Ruvinov Sergei , Hess Sonja , Schantz Rodolphe , Delmer Deborah P. , Wlodawer Alexander
Published: October 2002

The oligomeric state in solution of four plant annexins, namely Anx23(Ca38), Anx24(Ca32), Anx(Gh1), and Anx(Gh2), was characterized by sedimentation equilibrium analysis and gel filtration. All proteins were expressed and purified as amino‐terminal Hisn fusions. Sequencing of the Anx(Gh1) construct revealed distinct differences with the published sequence. Sedimentation equilibrium analysis of Anx23(Ca38), Anx24(Ca32), and Anx(Gh1) suggests monomer–trimer equilibria for each protein with association constants in the range of 0.9 × 1010−1.7 × 1011 M−2. All four proteins were subjected to analytical gel filtration under different buffer conditions. Observations from this experiment series agree quantitatively with the ultracentrifugation results, and strongly suggest calcium independence of the annexin oligomerization behavior; moreover, binding of calcium ions to the proteins seems to require disassembly of the oligomers. Anx(Gh2) showed a different elution profile than the other plant annexins; while having only a very small trimer content, this annexin seems to exist in a monomer–dimer equilibrium in solution.
A Topological Criterion for the Existence of Half‐Bound States
Authors: Carron Gilles
Published: October 2002

The following theorem is proved: if (M4n+1,g) is a complete Riemannian manifold and Σ ⊂ M is an oriented hypersurface partitioning M and with non‐zero signature, then the spectrum of the Hodge–deRham Laplacian is [0,∞]. This result is obtained by a new Callias‐type index. This new formula links half‐bound harmonic forms (that is, nearly L2 but not in L2) with the signature of Σ.
Measurement of cytoplasmic calcium concentration in the rods of wild‐type and transducin knock‐out mice
Authors: Woodruff Michael L. , Sampath A. P. , Matthews Hugh R. , Krasnoperova N. V. , Lem J. , Fain Gordon L.
Published: October 2002

A 10 μm spot of argon laser light was focused onto the outer segments of intact mouse rods loaded with fluo‐3, fluo‐4 or fluo‐5F, to estimate dark, resting free Ca2+ concentration ([Ca2+]i) and changes in [Ca2+]i upon illumination. Dye concentration was adjusted to preserve the normal physiology of the rod, and the laser intensity was selected to minimise bleaching of the fluorescent dye. Wild‐type mouse rods illuminated continuously with laser light showed a progressive decrease in fluorescence well fitted by two exponentials with mean time constants of 154 and 540 ms. Rods from transducin α‐subunit knock‐out (Trα–/–) animals showed no light‐dependent decline in fluorescence but exhibited an initial rapid component of fluorescence increase which could be fitted with a single exponential (τ∼1–4 ms). This fluorescence increase was triggered by rhodopsin bleaching, since its amplitude was reduced by pre‐exposure to bright bleaching light and its time constant decreased with increasing laser intensity. The rapid component was however unaffected by incorporation of the calcium chelator BAPTA and seemed therefore not to reflect an actual increase in [Ca2+]i. A similar rapid increase in fluorescence was also seen in the rods of wild‐type mice just preceding the fall in fluorescence produced by the light‐dependent decrease in [Ca2+]i. Dissociation constants were measured in vitro for fluo‐3, fluo‐4 and fluo‐5F with and without 1 mm Mg2+ from 20 to 37 °C. All three dyes showed a strong temperature dependence, with the dissociation constant changing by a factor of 3–4 over this range. Values at 37 °C were used to estimate absolute levels of rod [Ca2+]i. All three dyes gave similar values for [Ca2+]i in wild‐type rods of 250 ± 20 nm in darkness and 23 ± 2 nm after exposure to saturating light. There was no significant difference in dark [Ca2+]i between wild‐type and Trα–/– animals.
The mechanisms of interhemispheric inhibition in the human motor cortex
Authors: Daskalakis Zafiris J. , Christensen Bruce K. , Fitzgerald Paul B. , Roshan Lailoma , Chen Robert
Published: October 2002

Transcranial magnetic stimulation can be used to non‐invasively study inhibitory processes in the human motor cortex. Interhemispheric inhibition can be measured by applying a conditioning stimulus to the motor cortex resulting in inhibition of the contralateral motor cortex. Transcranial magnetic stimulation can also be used to demonstrate ipsilateral cortico‐cortical inhibition in the motor cortex. At least two different ipsilateral cortico‐cortical inhibitory processes have been identified: short interval intracortical inhibition and long interval intracortical inhibition. However, the relationship between interhemispheric inhibition and ipsilateral cortico‐cortical inhibition remains unclear. This study examined the relationship between interhemispheric inhibition, short interval intracortical inhibition and long interval intracortical inhibition. First, the effect of test stimulus intensity on each inhibitory process was studied. Second, the effects of interhemispheric inhibition on short interval intracortical inhibition and long interval intracortical inhibition on interhemispheric inhibition were examined. Motor evoked potentials were recorded from the right first dorsal interosseous muscle in 11 right‐handed healthy volunteers. For interhemispheric inhibition, conditioning stimuli were applied to the right motor cortex and test stimuli to the left motor cortex. For short interval intracortical inhibition and long interval intracortical inhibition, both conditioning stimuli and test stimuli were applied to the left motor cortex. With increasing test stimulus intensities, long interval intracortical inhibition and interhemispheric inhibition decreased, while short interval intracortical inhibition increased. Moreover, short interval intracortical inhibition was significantly reduced in the presence of interhemispheric inhibition. Interhemispheric inhibition was significantly reduced in the presence of long interval intracortical inhibition when matched for test motor evoked potential amplitude but the difference was not significant when matched for test pulse intensity. These findings suggest that both interhemispheric inhibition and long interval intracortical inhibition are predominately mediated by low threshold cortical neurons and may share common inhibitory mechanisms. In contrast, the mechanisms mediating short interval intracortical inhibition are probably different from those mediating long interval intracortical inhibition and interhemispheric inhibition although these systems appear to interact.
‐Dynamic representation of whisker deflection by synaptic potentials in spiny stellate and pyramidal cells in the barrels and septa of layer 4 rat somatosensory cortex
Authors: Brecht Michael , Sakmann Bert
Published: October 2002

Whole‐cell voltage recordings were made in vivo from excitatory neurons (n= 23) in layer 4 of the barrel cortex in urethane‐anaesthetised rats. Their receptive fields (RFs) for a brief whisker deflection were mapped, the position of the cell soma relative to barrel borders was determined for 15 cells and dendritic and axonal arbors were reconstructed for all cells. Three classes of neurons were identified: spiny stellate cells and pyramidal cells located in barrels and pyramidal cells located in septa. Dendritic and, with some exceptions, axonal arborisations of barrel cells were mostly restricted to the borders of a column with a cross sectional area of a barrel, defining a cytoarchitectonic barrel‐column. Dendrites and axons of septum cells, in contrast, mostly extended across barrel borders. The subthreshold RFs measured by evoked postsynaptic potentials (PSPs) comprised a principal whisker (PW) and several surround whiskers (SuWs) indicating that deflection of a single whisker is represented in multiple barrels and septa. Barrel cells responded with larger depolarisation to stimulation of the PW (13.7 ± 4.6 mV (mean ±S.D.), n= 10) than septum cells (5.7 ± 2.4 mV, n= 5), the gradient between peak responses to PW and SuW deflection was steeper and the latency of depolarisation onset was shorter (8 ± 1.4 ms vs. 11 ± 2 ms). In barrel cells the response onset and the peak to SuW deflection was delayed depending on the distance to the PW thus indicating that the spatial representation of a single whisker deflection in the barrel map is dynamic and varies on the scale of milliseconds to tens of milliseconds. Septum cells responded later and with comparable latencies to PW and SuW stimulation. Spontaneous (0.053 ± 0.12 action potentials (APs) s−1) and evoked APs (0.14 ± 0.29 APs per principal whisker (PW) stimulus) were sparse. We conclude that PSPs in ensembles of barrel cells represent dynamically the deflection of a single whisker with high temporal and spatial acuity, initially by the excitation in a single PW‐barrel followed by multi‐barrel excitation. This presumably reflects the divergence of thalamocortical projections to different barrels. Septum cell PSPs preferably represent multiple whisker deflections, but less dynamically and with less spatial acuity.
In vitro and in vivo analysis of the Effects of corticotropin releasing factor on rat dorsal vagal complex
Authors: Lewis Mark W. , Hermann Gerlinda E. , Rogers Richard C. , Travagli R. Alberto
Published: October 2002

In vivo and in vitro electrophysiological experiments were performed on the rat dorsal vagal complex (DVC, i.e. nucleus of the tractus solitarius, NTS, and dorsal motor nucleus of the vagus, DMV) to examine the effects of corticotropin releasing hormone (CRF) on the central components of the vago‐vagal reflex control of gastric function. When applied to gastrointestinal projecting DMV neurones, CRF (10‐300 nm) induced a concentration‐dependent membrane depolarization, an increase in action potential firing rate and decrease in amplitude of the action potential afterhyperpolarization (P < 0.05). Pretreatment with the non‐selective CRF antagonist, astressin (0.5‐1 μM) or the selective CRF2 receptor antagonist, astressin 2B (500 nm) attenuated the CRF‐induced increase in firing rate but did not alter basal discharge rate. CRF (30‐300 nm) increased the amplitude of excitatory postsynaptic currents (EPSCs) evoked by stimulation of the NTS (P < 0.05). An alteration in the paired pulse ratio indicated the EPSC's increase occurred due to actions at presynaptic sites. In the in vivo anaesthetized rat preparation, bilateral microinjections (20 fmol in 20 nl for each site) of CRF in the DVC decreased gastric motility in rats pretreated with the muscarinic agonist, bethanecol (P < 0.05). The effects of CRF were abolished by systemic administration of the NOS inhibitor, L‐NAME, or by bilateral vagotomy. We concluded that CRF had both a direct and an indirect excitatory effect on DMV neurones via activation of CRF2 receptors and the decrease in gastric motility observed following microinjection of CRF in the DVC is due to the activation of an inhibitory non‐adrenergic non‐cholinergic input to the gastrointestinal tract.
Reliability Modeling for Ball Grid Array Assembly With a Large Number of Warpage Affected Solder Joints
Authors: Chan Y. W. , Ju T. H. , Hareb Saeed A. , Lee Y. C. , Wu Jih-Shun , Lii Mirng-Ji
Published: October 2002

A reliability model is established to study thermal fatigue behavior of solder joints in plastic ball grid array (PBGA) assemblies. The model is able to simulate a configuration with a large number of warpage affected solder joints. For efficient computation, regression models are used to calculate the force acting on each solder joint to determine its height under different warpage conditions. With the height and specified solder parameters, the shapes of selected solder joints are calculated using the Surface Evolver. In addition, the displacements of these solder joints can be determined by a macro model using equivalent beams to represent hundreds of solder joints. With the shapes and displacements, three-dimensional micro models for the selected joints are established to compute strain energy densities during temperature cycling. The energy densities can be used to estimate fatigue lives through an empirical correlation. Two PBGA assemblies with 72-I/O cavity-up and 540-I/O cavity-down packages are studied using the reliability model. Silicon chip size and substrate thickness are critical to solder fatigue in the cavity-up assembly. Their effects are reduced substantially for the cavity-down assembly, which is more reliable due to small global thermal mismatch. However, its reliability is strongly affected by the warpage. The warpage changes the shapes of solder joints and can reduce the corner joint’s fatigue life from 20,000 to 7800 temperature cycles for an arch-type warpage of 0.28 mm across a 42.5 mm×42.5 mm region.
Lithium Doped Polyethylene-Glycol-Based Thermal Interface Pastes for High Thermal Contact Conductance
Authors: Xu Yunsheng , Luo Xiangcheng , Chung D. D. L.
Published: October 2002

Polyethylene-glycol-based thermal interface paste containing trifluoroacetic acid lithium salt (1.5 wt. percent optimum) and boron nitride particles (∼18.0 vol. percent optimum), as well as water and N, N-dimethylformamide for helping the dissociation of the salt to release Li+ ions, gives thermal contact conductance that is almost as high as that given by Sn-Pb solder, similar to that given by boron nitride particle filled sodium silicate, and much higher than that given by boron nitride particle filled silicone.
Design and Singularity Analysis of a 3-Translational-DOF In-Parallel Manipulator*
Authors: Romdhane L. , Affi Z. , Fayet M.
Published: October 2002

In this work, we shall present a novel design of a 3-translational-DOF in-parallel manipulator having 3 linear actuators. Three variable length legs constitute the actuators of this manipulator, whereas two other kinematic chains with passive joints are used to eliminate the three rotations of the platform with respect to the base. This design presents several advantages compared to other designs of similar 3-translational-dof parallel manipulators. First, the proposed design uses only revolute or spherical joints as passive joints and hence, it avoids problems that are inherent to the nature of prismatic joints when loaded in arbitrary way. Second, the actuators are chosen to be linear and to be located in the three legs since this design presents higher rigidity than other. In the second part of this paper, we addressed the problem of kinematic analysis of the proposed in-parallel manipulator. A mixed geometric and vector formulation is used to show that two solutions exist for the forward kinematic analysis. The problem of singularities is also investigated using the same method. In this work, we investigated the singularities of the active legs and the two types of singularity were identified: architectural singularities and configurational singularities. The singularity of the passive chains, used to restrict the motion of the platform to only three translations, is also investigated. In the last part of this paper, we built a 3D solid model of the platform and the amplitude of rotation due to the deformation of the different links under some realistic load was determined. This allowed us to estimate the “orientation error” of the platform due to external moments. Moreover, this analysis allowed us to compare the proposed design (over constrained) with a modified one (not over constrained). This comparison confirmed the conclusion that the over constraint design has a better rigidity.
Characterization of Stress at a Ceramic/Metal Joined Interface by the Vz Technique of Scanning Acoustic Microscopy
Authors: Miyasaka Chiaki , Tittmann Bernard R. , Tanaka Shun-Ichiro
Published: October 2002

It is well known that the process of heating and then cooling dissimilar materials introduces considerable stress at and near the interface. In this article, first, the surface wave velocity distributions obtained with the Vz curve technique were found to compare well with residual stress distribution measured by the finely collimated X-ray diffraction technique. Second, a delamination was introduced at the interface. The Vz curve technique was then used again to measure the surface acoustic wave velocity along the interface. The defective specimens showed significantly different patterns of surface acoustic wave velocities. Thus, this study presents useful guidelines in discriminating between sound and defective ceramic/metal joints by scanning acoustic microscopy.
Ultrasonic Stress Measurement and Material Characterization in Pressure Vessels, Piping, and Welds
Authors: Bray Don E.
Published: October 2002

A pressure vessel has been constructed for demonstrating the LCR ultrasonic technique for indicating changes in wall and weld stress. A special contoured LCR probe was designed and constructed, and the pressure vessel was fitted with strain gauges for monitoring the wall stress. At low wall stresses, below 4 ksi (26 MPa), the ultrasonic data showed considerable scatter. There is similar scatter in the zero pressure travel-times at individual locations around the vessel. At wall stresses of 4 ksi (26 MPa) and above, however, there is an almost linear relationship of stress and travel-time change. Measurements adjacent to an end weld also showed very good trends. Plots of travel times approaching a weld predict −27.5 ksi (−190 MPa) at 1 in. (25 mm) from the weld, compared to zero stress at 5.6 in. (142 mm) away from the weld. These results are consistent with results obtained by others on a similar weld using the blind hole drilling method.
Design and Analysis: Thermal Emulator Cubes for Opto-Electronic Stacked Processor
Authors: Gadag Shiva P. , Patra Susan K. , Ozguz Volkan , Marchand Phillipe , Esener Sadik
Published: October 2002

3D finite element modeling of thermal emulator cube and its composition consisting of composite stack of multi-layer chip are developed. Thermal analysis of the Multi-Chip Module consisting of 16 alternate layers Si processor and heat sink layers with Si spacers and AlN ceramic cap is undertaken. The various alternatives for design of the emulator cubes such as thermal cube floating in free-space, thermal cube-on-substrate, thermal cube-on-flex cable with a continuous joint of solder and thermal cube embedded in rectangular Si-spacer are investigated for their heat extraction capability. Thermal modeling of a composite structural unit stack of chip offers first hand information as to the operating performance of the entire thermal emulator cube to be used in the construction of buffer cube. The scientific understanding of the mode of heat transfer of the emulator cube, heat extraction of the various heat sink materials, ceramic and the metallic substrates are investigated. A thin sheet of ceramic (AlN) substrate is at least three times more effective in extraction of heat than thick block of steel under similar conditions. The homogeneous and heterogeneous nature of the composite structure of thermal emulator in heat transfer is analyzed. The primary and secondary hotspots in thermal cubes with AlN heat sink are found in thermal simulations. The mode of heat transfer advances normal to lateral and transverse directions of stacking from the central core of the cube towards the outward face. The sharp corners of the cube typically exhibit edge convection due to chilling effect. Buffer-on-flex cable is modeled with a continuous solder joint and its further improvement with alternate hinges of solder joints and micro-channels is proposed for enhanced heat transfer analysis. The embedded emulator cubes are developed for thermal analysis of the optical layers on top of buffer. The optical layers with an interconnection of solder joints on top of the embedded emulator cubes coupled with micro-channels and hinged solder joints will be used for further enhanced heat transfer and higher dissipation of heat 1∼3W/layer resulting in efficient and cost effective thermal management technique.
Fast multipole accelerated boundary integral equation methods
Authors: Nishimura N
Published: October 2002

Fundamentals of Fast Multipole Method (FMM) and FMM accelerated Boundary Integral Equation Method (BIEM) are presented. Developments of FMM accelerated BIEM in the Laplace and Helmholtz equations, wave equation, and heat equation are reviewed. Applications of these methods in computational mechanics are surveyed. This review article contains 173 references.
Recent research advances in the dynamic behavior of shells: 1989-2000, Part 1: Laminated composite shells
Authors: Qatu Mohamad S
Published: October 2002

Laminated composite shells are increasingly being used in various engineering applications including aerospace, mechanical, marine, and automotive engineering. With the increasing awareness of and sensitivity to structural noise and vibration, research covering the dynamic behavior of composite shells has received considerable attention. The purpose of this article is to review most of the recent research done in this field. Review of the literature on the dynamic behavior of homogeneous shells is covered in Part 2 of this article to be published in the September 2002 issue of AMR. Research on shell dynamics is found to be mainly free vibration analyses. The review is conducted with emphasis given to the theory being applied (thin, thick, 3D, nonlinear, …), the analysis method (exact, Ritz, finite elements, …), complicating effects (initial stress, imperfection, added masses and springs, elastic supports, rotating shells, and others), and the various shell geometries that were subject to vibration research (cylindrical, conical, spherical, and others). There are 374 references cited in this review article.
Embedded Active Sensors for In-Situ Structural Health Monitoring of Thin-Wall Structures
Authors: Giurgiutiu Victor , Zagrai Andrei , Bao JingJing
Published: October 2002

The use of embedded piezoelectric-wafer active-sensors for in-situ structural health monitoring of thin-wall structures is presented. Experiments performed on aircraft-grade metallic specimens of various complexities exemplified the detection procedures for near-field and far-field damage. For near-field damage detection, the electro-mechanical (E/M) impedance method was used. Systematic experiments conducted on statistical samples of incrementally damaged specimens were followed by illustrative experiments on realistic aging aircraft panels. For far-field damage detection, guided ultrasonic Lamb waves were utilized in conjunction with the pulse-echo technique. Systematic experiments conducted on aircraft-grade metallic plates were used to develop the method, while experiments performed on realistic aging-aircraft panels exemplified the crack detection procedure.
Design of a Screw Jack Mechanism to Avoid Self-excited Vibrations
Authors: Gallina Paolo , Giovagnoni Marco
Published: October 2002

This paper deals with vibratory phenomena that are encountered in screw jack mechanisms, down-motion especially. One can find many practical instances where such mechanisms are subject to vibratory conditions. Besides producing loud noise, vibrations can easily damage the mechanism. Although the screw jack mechanism has been widely employed, its behavior is still not fully understood. In order to explain the vibration phenomenon, we propose a simple two D.o.F. dynamic model. Using this kind of model, it is shown that vibrations can be avoided by reducing the axial stiffness of the screw.