bluuebunny/crossref_metadata_2025 huggingface dataset:
Rapid and simultaneous detection of human hepatitis B virus and hepatitis C virus antibodies based on a protein chip assay using nano-gold immunological amplification and silver staining method
Authors: Duan Lianlian , Wang Yefu , Li Shawn Shun-cheng , Wan Zhixiang , Zhai Jianxin
Published: July 2005

Background

Viral hepatitis due to hepatitis B virus and hepatitis C virus are major public health problems all over the world. Traditional detection methods including polymerase chain reaction (PCR)-based assays and enzyme-linked immunosorbent assays (ELISA) are expensive and time-consuming. In our assay, a protein chip assay using Nano-gold Immunological Amplification and Silver Staining (NIASS) method was applied to detect HBV and HCV antibodies rapidly and simultaneously.

Methods

Chemically modified glass slides were used as solid supports (named chip), on which several antigens, including HBsAg, HBeAg, HBcAg and HCVAg (a mixture of NS3, NS5 and core antigens) were immobilized respectively. Colloidal nano-gold labelled staphylococcal protein A (SPA) was used as an indicator and immunogold silver staining enhancement technique was applied to amplify the detection signals, producing black image on array spots, which were visible with naked eyes. To determine the detection limit of the protein chip assay, a set of model arrays in which human IgG was spotted were structured and the model arrays were incubated with different concentrations of anti-IgG. A total of 305 serum samples previously characterized with commercial ELISA were divided into 4 groups and tested in this assay.

Results

We prepared mono-dispersed, spherical nano-gold particles with an average diameter of 15 ± 2 nm. Colloidal nano-gold-SPA particles observed by TEM were well-distributed, maintaining uniform and stable. The optimum silver enhancement time ranged from 8 to 12 minutes. In our assay, the protein chips could detect serum antibodies against HBsAg, HBeAg, HBcAg and HCVAg with the absence of the cross reaction. In the model arrays, the anti-IgG as low as 3 ng/ml could be detected. The data for comparing the protein chip assay with ELISA indicated that no distinct difference (P > 0.05) existed between the results determined by our assay and ELISA respectively.

Conclusion

Results showed that our assay can be applied with serology for the detection of HBV and HCV antibodies rapidly and simultaneously in clinical detection.
Probable neuroimmunological link between Toxoplasma and cytomegalovirus infections and personality changes in the human host
Authors: Novotná Martina , Hanusova Jitka , Klose Jiří , Preiss Marek , Havlicek Jan , Roubalová Kateřina , Flegr Jaroslav
Published: July 2005

Background

Recently, a negative association between Toxoplasma-infection and novelty seeking was reported. The authors suggested that changes of personality trait were caused by manipulation activity of the parasite, aimed at increasing the probability of transmission of the parasite from an intermediate to a definitive host. They also suggested that low novelty seeking indicated an increased level of the neurotransmitter dopamine in the brain of infected subjects, a phenomenon already observed in experimentally infected rodents. However, the changes in personality can also be just a byproduct of any neurotropic infection. Moreover, the association between a personality trait and the toxoplasmosis can even be caused by an independent correlation of both the probability of Toxoplasma-infection and the personality trait with the third factor, namely with the size of living place of a subject. To test these two alternative hypotheses, we studied the influence of another neurotropic pathogen, the cytomegalovirus, on the personality of infected subjects, and reanalyzed the original data after the effect of the potential confounder, the size of living place, was controlled.

Methods

In the case-control study, 533 conscripts were tested for toxoplasmosis and presence of anti-cytomegalovirus antibodies and their novelty seeking was examined with Cloninger's TCI questionnaire. Possible association between the two infections and TCI dimensions was analyzed.

Results

The decrease of novelty seeking is associated also with cytomegalovirus infection. After the size of living place was controlled, the effect of toxoplasmosis on novelty seeking increased. Significant difference in novelty seeking was observed only in the largest city, Prague.

Conclusion

Toxoplasma and cytomegalovirus probably induce a decrease of novelty seeking. As the cytomegalovirus spreads in population by direct contact (not by predation as with Toxoplasma), the observed changes are the byproduct of brain infections rather than the result of manipulation activity of a parasite. Four independent lines of indirect evidence, namely direct measurement of neurotransmitter concentration in mice, the nature of behavioral changes in rodents, the nature of personality changes in humans, and the observed association between schizophrenia and toxoplasmosis, suggest that the changes of dopamine concentration in brain could play a role in behavioral changes of infected hosts.
Further evidence for increased macrophage migration inhibitory factor expression in prostate cancer
Authors: Meyer-Siegler Katherine L , Iczkowski Kenneth A , Vera Pedro L
Published: July 2005

Background

Macrophage migration inhibitory factor (MIF) is a cytokine associated with prostate cancer, based on histologic evidence and circulating (serum) levels.

Recent studies from another laboratory failed to document these results. This study's aims were to extend and confirm our previous data, as well as to define possible mechanisms for the discrepant results. Additional aims were to examine MIF expression, as well as the location of MIF's receptor, CD74, in human prostatic adenocarcinoma compared to matched benign prostate.

Methods

MIF amounts were determined in random serum samples remaining following routine PSA screening by ELISA. Native, denaturing and reducing polyacrylamide gels and Western blot analyses determined the MIF form in serum. Prostate tissue arrays were processed for MIF in situ hybridization and immunohistochemistry for MIF and CD74. MIF released into culture medium from normal epithelial, LNCaP and PC-3 cells was detected by Western blot analysis.

Results

Median serum MIF amounts were significantly elevated in prostate cancer patients (5.87 ± 3.91 ng/ml; ± interquartile range; n = 115) compared with patients with no documented diagnosis of prostate cancer (2.19 ± 2.65 ng/ml; n = 158). ELISA diluent reagents that included bovine serum albumin (BSA) significantly reduced MIF serum detection (p < 0.01). MIF mRNA was localized to prostatic epithelium in all samples, but cancer showed statistically greater MIF expression. MIF and its receptor (CD74) were localized to prostatic epithelium. Increased secreted MIF was detected in culture medium from prostate cancer cell lines (LNCaP and PC-3).

Conclusion

Increased serum MIF was associated with prostate cancer. Diluent reagents that included BSA resulted in MIF serum immunoassay interference. In addition, significant amounts of complexed MIF (180 kDa under denaturing conditions by Western blot) found in the serum do not bind to the MIF capture antibody. Increased MIF mRNA expression was observed in prostatic adenocarcinoma compared to benign tissue from matched samples, supporting our earlier finding of increased MIF gene expression in prostate cancer.
Small philanthropy and big science: the RETROVIROLOGY prize and Stephen P. Goff
Authors: Jeang Kuan-Teh
Published: July 2005

Stephen P. Goff wins the 2005 RETROVIROLOGY prize.
Chiropractic as spine care: a model for the profession
Authors: Nelson Craig F , Lawrence Dana J , Triano John J , Bronfort Gert , Perle Stephen M , Metz R Douglas , Hegetschweiler Kurt , LaBrot Thomas
Published: July 2005

Background

More than 100 years after its inception the chiropractic profession has failed to define itself in a way that is understandable, credible and scientifically coherent. This failure has prevented the profession from establishing its cultural authority over any specific domain of health care.

Objective

To present a model for the chiropractic profession to establish cultural authority and increase market share of the public seeking chiropractic care.

Discussion

The continued failure by the chiropractic profession to remedy this state of affairs will pose a distinct threat to the future viability of the profession. Three specific characteristics of the profession are identified as impediments to the creation of a credible definition of chiropractic: Departures from accepted standards of professional ethics; reliance upon obsolete principles of chiropractic philosophy; and the promotion of chiropractors as primary care providers. A chiropractic professional identity should be based on spinal care as the defining clinical purpose of chiropractic, chiropractic as an integrated part of the healthcare mainstream, the rigorous implementation of accepted standards of professional ethics, chiropractors as portal-of-entry providers, the acceptance and promotion of evidence-based health care, and a conservative clinical approach.

Conclusion

This paper presents the spine care model as a means of developing chiropractic cultural authority and relevancy. The model is based on principles that would help integrate chiropractic care into the mainstream delivery system while still retaining self-identity for the profession.
Targeting Signal Transduction Pathways in Colorectal Cancer—More Than Skin Deep
Authors: Cohen Steven J. , Cohen Roger B. , Meropol Neal J.
Published: July 2005

Colorectal cancer is the second leading cause of cancer death in the United States. The nihilism that previously often characterized the treatment of patients with this disease has been replaced by a measure of excitement, given recent therapeutic advances. These advances have been stimulated in part through identification of cellular processes characteristic of colorectal cancers that permit therapeutic targeting with favorable therapeutic index. Inhibition of the epidermal growth factor receptor in the clinic has provided proof of principle that interruption of signal transduction cascades in patients with colorectal cancer has therapeutic potential. This experience has also taught us that resistance to such rationally developed targeted therapeutic strategies is common. In this article, we review the role of signal transduction in colorectal cancer, introduce promising molecular targets, and outline therapeutic approaches under development. We will describe the barriers to success, and highlight paradigms to facilitate rapid and successful evaluation of new agents, in a clinical context that has (by virtue of recent clinical successes) become a somewhat crowded playing field.
Twelve Issues for Cognitive Science
Authors: Norman Donald A.
Published: July 2005

I am struck by how little is known about so much of cognition. One goal of this paper is to argue for the need to consider a rich set of interlocking issues in the study of cognition. Mainstream work in cognition—including my own—ignores many critical aspects of animate cognitive systems. Perhaps one reason that existing theories say so little relevant to real world activities is the neglect of social and cultural factors, of emotion, and of the major points that distinguish an animate cognitive system from an artificial one: the need to survive, to regulate its own operation, to maintain itself, to exist in the environment, to change from a small, uneducated, immature system to an adult, developed, knowledgeable one.

Human cognition is not the same as artificial cognition, if only because the human organism must also be concerned with the problems of life, of development, of survival. There must be a regulatory system that interacts with the cognitive component. And it may well be that it is the cognitive component that is subservient, evolved primarily for the benefit of the regulatory system, working through the emotions, through affect.

I argue that several concepts must become fundamental parts of the study of cognition, including the roles of culture, of social interaction, of emotions, and of motivation. I argue that there are at least 12 issues that should comprise the study of cognition, and thereby, the field of Cognitive Science. We need to study a wide variety of behavior before we can hope to understand a single class. Cognitive scientists as a whole ought to make more use of evidence from the neurosciences, from brain damage and mental illness, from cognitive sociology and anthropology, and from clinical studies of the human. These must be accompanied, of course, with the study of language, of the psychological aspects of human processing structures, and of artificially intelligent mechanisms. The study of Cognitive Science requires a complex interaction among different issues of concern, an interaction that will not be properly understood until all parts are understood, with no part independent of the others, the whole requiring the parts, and the parts the whole.
K‐Lines: A theory of Memory
Authors: Minsky Marvin
Published: July 2005

Most theories of memory suggest that when we learn or memorize something, some drepresentation of that something is constructed, stored and later retrieved. This raises questions like:

How is information represented?

How is it stored?

How is it retrieved?

Then, how is it used?

This paper tries to deal with all these at once. When you get an idea and want to “remember” it, you create a “K‐line” for it. When later activated, the K‐line induces a partial mental state resembling the one that created it. A “partial mental state” is a subset of those mental agencies operating at one moment. This view leads to many ideas about the development, structure and physiology of memory, and about how to implement framelike representations in a distributed processor.
On Throwing Out the Baby with the Bathwater: A Reply to Black and Wilensky's Evaluation of Story Grammars*
Authors: Mandler Jean M. , Johnson Nancy S.
Published: July 2005

A number of criticisms of a recent paper byare made. (1) In attempting to assess the observational adequacy of story grammars, they state that a context‐free grammar cannot handle discontinuous elements; however, they do not show that such elements occur in the domain to which the grammars apply. Further, they do not present adequate evidence for their claim that there are acceptable stories not accounted for by existing grammars and that the grammars will accept nonstories such as procedures. (2) They state that it has been proven that under natural conditions children cannot learn transformational grammars, which is a misrepresentation of the learnability proofs which have been offered. (3) Most important, they take an unduly narrow approach to story understanding by claiming that people only understand story content and do not have knowledge of story structure which is useful in comprehension or memory. Counterevidence from the literature is cited which indicates that such knowledge is both useful and used, and a number of methods for assessing the psychological adequacy of structural models are discussed.
Simulating a Skilled Typist: A Study of Skilled Cognitive‐Motor Performance
Authors: Rumelhart David E. , Norman Donald A.
Published: July 2005

We review the major phenomena of skilled typing and propose a model for the control of the hands and fingers during typing. The model is based upon an Activation‐Trigger‐Schema system in which a hierarchical structure of schemata directs the selection of the letters to be typed and, then, controls the hand and finger movements by a cooperative, relaxation algorithm. The interactions of the patterns of activation and inhibition among the schemata determine the temporal ordering for launching the keystrokes. To account for the phenomena of doubling errors, the model has only “type” schemata—no “token” schemata—with only a weak binding between the special schema that signals a doubling, and its argument. The model exists as a working computer simulation and produces an output display of the hands and fingers moving over the keyboard. It reproduces some of the major phenomena of typing, including the interkeystroke interval times, the pattern of transposition errors found in skilled typists, and doubling errors. Although the model is clearly inadequate or wrong in some of its features and assumptions, it serves as a useful first approximation for the understanding of skilled typing.
A Temporal Logic for Reasoning about Processes and Plans*
Authors: McDermott Drew
Published: July 2005

Much previous work in artificial intelligence has neglected representing time in all its complexity. In particular, it has neglected continuous change and the indeterminacy of the future. To rectify this, I have developed a first‐order temporal logic, in which it is possible to name and prove things about facts, events, plans, and world histories. In particular, the logic provides analyses of causality, continuous change in quantities, the persistence of facts (the frame problem), and the relationship between tasks and actions. It may be possible to implement a temporal‐inference machine based on this logic, which keeps track of several “maps” of a time line, one per possible history.
A Model of the Time Course and Content of Reading*
Authors: Thibadeau Robert , Just Marcel Adam , Carpenter Patricia A.
Published: July 2005

This paper describes a computer simulation of reading that is strongly driven by eye fixation data from human readers. The simulation, READER, is a natural language understanding system that reads a text word by word and whose processing cycles on each word have some correspondence with the human gaze duration on that word. READER operates within a newly developed information processing architecture, a Collaborative, Activation‐based, Production System (CAPS) that permits the modeling of the temporal properties of human comprehension. CAPS allows for concurrent, collaborative execution of processes operating at different levels of analysis. As READER encounters each successive word, the word is operated on by processes at the levels of word encoding, lexical access, syntactic and semantic analysis, and referential and schema‐level processes. Like human readers, READER uses a strategy of immediacy of comprehension, attempting to interpret each word as soon as it is encountered, rather than unnecessarily buffering information. A major contribution of this simulation is its use of human performance characteristics in constraining and determining the model's mechanisms.
Instance‐based learning in dynamic decision making
Authors: Gonzalez Cleotilde , Lerch Javier F. , Lebiere Christian
Published: July 2005

This paper presents a learning theory pertinent to dynamic decision making (DDM) called instancebased learning theory (IBLT). IBLT proposes five learning mechanisms in the context of a decision‐making process: instance‐based knowledge, recognition‐based retrieval, adaptive strategies, necessity‐based choice, and feedback updates. IBLT suggests in DDM people learn with the accumulation and refinement of instances, containing the decision‐making situation, action, and utility of decisions. As decision makers interact with a dynamic task, they recognize a situation according to its similarity to past instances, adapt their judgment strategies from heuristic‐based to instance‐based, and refine the accumulated knowledge according to feedback on the result of their actions. The IBLT's learning mechanisms have been implemented in an ACT‐R cognitive model. Through a series of experiments, this paper shows how the IBLT's learning mechanisms closely approximate the relative trend magnitude and performance of human data. Although the cognitive model is bounded within the context of a dynamic task, the IBLT is a general theory of decision making applicable to other dynamic environments.
Categorization as causal reasoning⋆
Authors: Rehder Bob
Published: July 2005

A theory of categorization is presented in which knowledge of causal relationships between category features is represented in terms of asymmetric and probabilistic causal mechanisms. According to causal‐model theory, objects are classified as category members to the extent they are likely to have been generated or produced by those mechanisms. The empirical results confirmed that participants rated exemplars good category members to the extent their features manifested the expectations that causal knowledge induces, such as correlations between feature pairs that are directly connected by causal relationships. These expectations also included sensitivity to higher‐order feature interactions that emerge from the asymmetries inherent in causal relationships. Quantitative fits of causal‐model theory were superior to those obtained with extensions to traditional similarity‐based models that represent causal knowledge either as higher‐order relational features or “prior exemplars” stored in memory.
Spatial representations activated during real‐time comprehension of verbs
Authors: Richardson Daniel C. , Spivey Michael J. , Barsalou Lawrence W. , McRae Ken
Published: July 2005

Previous research has shown that na_ve participants display a high level of agreement when asked to choose or drawschematic representations, or image schemas, of concrete and abstract verbs [Proceedings of the 23rd Annual Meeting of the Cognitive Science Society, 2001, Erlbaum, Mawhah, NJ, p. 873]. For example, participants tended to ascribe a horizontal image schema to push, and a vertical image schema to respect. This consistency in offline data is preliminary evidence that language invokes spatial forms of representation. It also provided norms that were used in the present research to investigate the activation of spatial image schemas during online language comprehension. We predicted that if comprehending a verb activates a spatial representation that is extended along a particular horizontal or vertical axis, it will affect other forms of spatial processing along that axis. Participants listened to short sentences while engaged in a visual discrimination task (Experiment 1) and a picture memory task (Experiment 2). In both cases, reaction times showed an interaction between the horizontal/vertical nature of the verb's image schema, and the horizontal/vertical position of the visual stimuli. We argue that such spatial effects of verb comprehension provide evidence for the perceptual–motor character of linguistic representations.
CAB: Connectionist Analogy Builder
Authors: Larkey Levi B. , Love Bradley C.
Published: July 2005

The ability to make informative comparisons is central to human cognition. Comparison involves aligning two representations and placing their elements into correspondence. Detecting correspondences is a necessary component of analogical inference, recognition, categorization, schema formation, and similarity judgment. Connectionist Analogy Builder (CAB) determines correspondences through a simple iterative computation that matches elements in one representation with elements playing compatible roles in the other representation while simultaneously enforcing structural constraints. CAB shows promise as a process model of comparison as its performance can be related to human performance (e.g., solution trajectory, error patterns, time‐on‐task). Furthermore, CAB's bounded working memory allows it to account for the inherent capacity limitations of human processing. CAB's strengths are its parsimony, transparency of operations, and ability to generate performance predictions. In this paper, CAB is evaluated against benchmark phenomena from the analogy literature.
Lexical effects on compensation for coarticulation: a tale of two systems?
Authors: Magnuson James S. , McMurray Bob , Tanenhaus Michael K. , Aslin Richard N.
Published: July 2005

We reply to McQueen's commentary by comparing the parsimony of his account of relevant data and the computational model he favors with the explanation and model we favor. His account requires multiple independent explanations and mechanisms. Ours requires one: lexical feedback.
SPO11 is required for sex-body formation, and Spo11 heterozygosity rescues the prophase arrest ofAtm-/- spermatocytes
Authors: Bellani Marina A. , Romanienko Peter J. , Cairatti Damian A. , Camerini-Otero R. Daniel
Published: July 2005

SPO11 introduces double-strand breaks (DSBs) that trigger the phosphorylation of H2AX during meiotic prophase. In mice, SPO11 is strictly required for initiation of meiotic recombination and synapsis, yet SPO11 is still considered to be dispensable for sex-body formation in mouse spermatocytes. We provide conclusive evidence showing that functional SPO11, and consequently recombination and synapsis, are required for phosphorylation of H2AX in the X-Y chromatin and for sex-body formation in mouse spermatocytes. We investigated the role in meiosis of the three kinases [ATM (ataxia telangiectasia mutated), ATR (ataxia-telangiectasia- and Rad-3-related) and DNA-PKcs (DNA-dependent-protein-kinase catalytic subunit)] known to phosphorylate H2AX in mitotic cells. We found that DNA-PKcs can be ruled out as an essential kinase in this process, whereas ATM is strictly required for the chromatin-wide phosphorylation of H2AX occurring in leptotene spermatocytes in response to DSBs. Remarkably, we discovered that Spo11 heterozygosity can rescue the prophase-I-arrest characteristic of ATM-deficient spermatocytes. Characterization of the rescued Atm-/-Spo11+/- mutant indicates that ATM is dispensable for sex-body formation and phosphorylation of H2AX in this subnuclear domain. The co-localization of ATR, phosphorylated H2AX and the sex chromatin observed in the Atm-/-Spo11+/- mutant, along with ATR transcription kinetics during the first wave of spermatogenesis, confirm and expand recent findings indicating that ATR is the kinase involved in H2AX phosphorylation in the sex body.
Running performance has a structural basis
Authors: Weyand Peter G. , Davis J. Adam
Published: July 2005

The body sizes of highly adapted human and other mammalian runners vary in accordance with specific performance needs. Sprint specialists are relatively massive and muscular while endurance specialists are conspicuously limited both in body and in muscle mass. We hypothesized that the greater body masses of faster specialists are directly related to the greater ground support forces required to attain faster running speeds. Using human runners as a test case, we obtained mean values for body mass, stature and racing speed for the world's fastest 45 male and female specialists, respectively, over the past 14 years (1990–2003) at each of eight standard track racing distances from 100 to 10,000 m. Mass-specific ground support force requirements were estimated from racing speeds using generalized support force–speed relationships derived from 18 athletic subjects. We find a single relationship between mass, stature and event-specific ground support force requirements that spans the entire continuum of specializations and applies both to male and to female runners [body mass (kg)=mass-specific support force ×stature2 (m) × a constant; N=16 group means, R2=0.97; where the ideal mass constant, D=10 kg m–2]. We conclude that running performance has a common structural basis.
V-ATPase expression during development ofArtemia franciscanaembryos: potential role for proton gradients in anoxia signaling
Authors: Covi Joseph A. , Hand Steven C.
Published: July 2005

Under anoxia, Artemia franciscana embryos downregulate metabolic processes and approach an ametabolic state. Entrance into this quiescent state is accompanied by a profound acidification of the intracellular space, and more than two decades of research now clearly demonstrates that this acidification is critical to metabolic downregulation in anoxic embryos. However, the proximal mechanisms responsible for the pH shift remain largely unidentified. Here, we report evidence demonstrating expression of the V-ATPase in encysted embryos and present an argument for its involvement in the intracellular acidification induced by anoxia. We identified a single B-subunit cDNA sharing the greatest degree of sequence similarity with`generalist-type' homologues from mammals (brain-type) and invertebrates. Quantitative analysis of B-subunit mRNA demonstrates differential expression throughout early development, and western blot analyses confirm the expression of at least six V-ATPase subunits in both heavy membranes and microsomal vesicles. The critical need for proton pumping during the anoxia-tolerant stage of development is demonstrated by incubation with the V-ATPase inhibitor bafilomycin A1, which halts embryonic development. Importantly, net proton flux from V-ATPase-acidified compartments to the surrounding cytoplasm is likely under anoxia and may significantly contribute to the enigmatic acidification critical to quiescence.
Aquaporin-3 expressed in the basolateral membrane of gill chloride cells in Mozambique tilapia Oreochromis mossambicus adapted to freshwater and seawater
Authors: Watanabe Soichi , Kaneko Toyoji , Aida Katsumi
Published: July 2005

We have cloned a homologue of mammalian aquaporin-3 (AQP3) from gills of Mozambique tilapia using a reverse transcription-polymerase chain reaction(RT-PCR). The deduced amino acid sequence shared 64–75% homology with other vertebrate AQP3 homologues. RT-PCR revealed that tilapia AQP3 was expressed in the brain, pituitary, kidney, spleen, intestine, skin, eye and gill in tilapia adapted to freshwater (FW) and seawater (SW). We also examined functional characteristics of tilapia AQP3 using Xenopus oocytes as an in vitro transcribed cRNA expression system. Osmotic water permeability (Pf) of Xenopus oocytes expressing tilapia AQP3 was about 30-fold higher than that of control oocytes, and was 80% inhibited by treatment with 0.3 mmol l–1 HgCl2. Light-microscopic immunocytochemistry of branchial epithelia revealed that tilapia AQP3 was expressed in gill chloride cells of FW- and SW-adapted tilapia. Electron-microscopic immunocytochemistry further demonstrated that tilapia AQP3 was localized in the basolateral membrane of gill chloride cells. Basolateral localization of AQP3 in gill chloride cells suggests that AQP3 is involved in regulatory volume changes and osmoreception, which could trigger functional differentiation of chloride cells.
Gene expression after freshwater transfer in gills and opercular epithelia of killifish: insight into divergent mechanisms of ion transport
Authors: Scott Graham R. , Claiborne James B. , Edwards Susan L. , Schulte Patricia M. , Wood Chris M.
Published: July 2005

We have explored the molecular basis for differences in physiological function between the gills and opercular epithelium of the euryhaline killifish Fundulus heteroclitus. These tissues are functionally similar in seawater, but in freshwater the gills actively absorb Na+ but not Cl–, whereas the opercular epithelium actively absorbs Cl– but not Na+. These differences in freshwater physiology are likely due to differences in absolute levels of gene expression (measured using real-time PCR), as several proteins important for Na+ transport, namely Na+,H+-exchanger 2 (NHE2), carbonic anhydrase 2 (CA2),Na+,HCO3–cotransporter 1, and V-type H+-ATPase, were expressed at 3- to over 30-fold higher absolute levels in the gills. In gills, transfer from 10% seawater to freshwater increased the activity of Na+,K+-ATPase by twofold (from 12 h to 7 days), increased the expression of NHE2 (at 12 h) and CA2 (from 12 h to 7 days), and decreased the expression of NHE3 (from 12 h to 3 days). In opercular epithelium, NHE2 was not expressed; furthermore,Na+,K+-ATPase activity was unchanged after transfer to freshwater, CA2 mRNA levels decreased, and NHE3 levels increased. Consistent with their functional similarities in seawater, killifish gills and opercular epithelium expressed Na+,K+-ATPase α1a,Na+,K+,2Cl–cotransporter 1 (NKCC1),cystic fibrosis transmembrane conductance regulator (CFTR)Cl– channel and the signalling protein 14-3-3a at similar absolute levels. Furthermore, NKCC1 and CFTR were suppressed equally in each tissue after freshwater transfer, and 14-3-3a mRNA increased in both. These results provide insight into the mechanisms of ion transport by killifish gills and opercular epithelia, and demonstrate a potential molecular basis for the differences in physiological function between these two organs.
The mechanics of jumpingversussteady hopping in yellow-footed rock wallabies
Authors: McGowan C. P. , Baudinette R. V. , Usherwood J. R. , Biewener A. A.
Published: July 2005

The goal of our study was to explore the mechanical power requirements associated with jumping in yellow-footed rock wallabies and to determine how these requirements are achieved relative to steady-speed hopping mechanics. Whole body power output and limb mechanics were measured in yellow-footed rock wallabies during steady-speed hopping and moving jumps up to a landing ledge 1.0 m high (∼3 times the animals' hip height). High-speed video recordings and ground reaction force measurements from a runway-mounted force platform were used to calculate whole body power output and to construct a limb stiffness model to determine whole limb mechanics. The combined mass of the hind limb extensor muscles was used to estimate muscle mass-specific power output. Previous work suggested that a musculoskeletal design that favors elastic energy recovery, like that found in tammar wallabies and kangaroos,may impose constraints on mechanical power generation. Yet rock wallabies regularly make large jumps while maneuvering through their environment. As jumping often requires high power, we hypothesized that yellow-footed rock wallabies would be able to generate substantial amounts of mechanical power. This was confirmed, as we found net extensor muscle power outputs averaged 155 W kg–1 during steady hopping and 495 W kg–1during jumping. The highest net power measured reached nearly 640 W kg–1. As these values exceed the maximum power-producing capability of vertebrate skeletal muscle, we suggest that back, trunk and tail musculature likely play a substantial role in contributing power during jumping. Inclusion of this musculature yields a maximum power output estimate of 452 W kg–1 muscle.

Similar to human high-jumpers, rock wallabies use a moderate approach speed and relatively shallow leg angle of attack (45–55°) during jumps. Additionally, initial leg stiffness increases nearly twofold from steady hopping to jumping, facilitating the transfer of horizontal kinetic energy into vertical kinetic energy. Time of contact is maintained during jumping by a substantial extension of the leg, which keeps the foot in contact with the ground.
Cardioprotective effects of KATP channel activation during hypoxia in goldfish Carassius auratus
Authors: Chen Jerri , Zhu Julia X. , Wilson Ingred , Cameron John S.
Published: July 2005

The activation of ATP-sensitive potassium (KATP) ion channels in the heart is thought to exert a cardioprotective effect under low oxygen conditions, possibly enhancing tolerance of environmental hypoxia in aquatic vertebrates. The purpose of this study was to examine the possibility that hypoxia-induced activation of cardiac KATP channels, whether in the sarcolemma (sarcKATP) or mitochondria (mitoKATP),enhances viability in cardiac muscle cells from a species highly tolerant of low oxygen environments, the goldfish Carassius auratus. During moderate hypoxia (6–7 kPa), the activation of sarcKATPchannels was indicated by a reduction in transmembrane action potential duration (APD). This response to hypoxia was mimicked by the NO-donor SNAP(100 μmol l–1) and the stable cGMP analog 8-Br-cGMP, but abolished by glibenclamide or l-NAME, an inhibitor of NO synthesis. The mitoKATP channel opener diazoxide did not affect APD. Isolated ventricular muscle cells were then incubated under normoxic and hypoxic conditions. Cell viability was decreased in hypoxia; however, the negative effects of low oxygen were reduced during simultaneous exposure to SNAP,8-Br-cGMP, and diazoxide. The cardioprotective effect of diazoxide, but not 8-Br-cGMP, was reduced by the mitoKATP channel blocker 5-HD. These data suggest that hypoxia-induced activation of sarcKATP or mitoKATP channels could enhance tolerance of low-oxygen environments in this species, and that sarcKATP activity is increased through a NO and cGMP-dependent pathway.
Interconnected vehicle suspension
Authors: Smith M C , Walker G W
Published: July 2005

This paper introduces a class of passive interconnected suspensions, defined mathematically in terms of their mechanical admittance matrices, with the purpose of providing greater freedom to specify independently bounce, pitch, roll, and warp dynamics than conventional (passive) suspension arrangements. Two alternative realization schemes are described that are capable of implementing this class (under ideal assumptions). The first scheme incorporates an interconnected multilever arrangement consisting of four separate hydraulic circuits, which transforms the separate wheel station displacements to bounce, pitch, roll, and warp motions. Four separate mechanical admittances are connected across the transformed terminals of the multilever. The second scheme is kinematically equivalent to the first but the multilever part consists of four modular subsystems to achieve the same kinematic transformation. The purpose of the class is to allow a high degree of independence between the modes of vehicle motion, e.g. low warp stiffness independent of front and rear anti-roll stiffness. Practical issues that might be involved in implementing the realization schemes are discussed, as well as generalizations to two-and six-wheeled vehicles.
An automotive engine charge-air intake conditioner system: Thermodynamic analysis of performance characteristics
Authors: Taitt D W , Garner C P , Swain E , Bassett M D , Pearson R J , Turner J W G
Published: July 2005

A first law thermodynamic model has been developed and used to characterize the performance of an automotive engine charge-air intake conditioner system. This system employs a compressor, intercooler, and expander to provide increased charge density with the possibility of reducing, the charge-air temperature below the sink temperature. The model was validated against experimental measurements. The variation of system effectiveness with compressor, intercooler, and expander efficiency was quantified and system operating limits were identified. While the expander was found to have a greater effect than the compressor, the performance of the system was shown to be most dependent upon intercooler effectiveness.
Development of producer gas engines
Authors: Sridhar G , Sridhar H V , Dasappa S , Paul P J , Rajan N K S , Mukunda H S
Published: July 2005

This paper summarizes the findings involved in the development of producer gas fuelled reciprocating engines over a time frame of six years. The high octane rating, ultra clean, and low-energy density producer gas derived from biomass has been examined. Development efforts are aimed at a fundamental level, wherein the parametric effects of the compression ratio and ignition timing on the power output are studied. These findings are subsequently applied in the adaptation of commercially available gas engines at two different power levels and make. Design of a producer gas carburettor also formed a part of this developmental activity. The successful operations with producer gas fuel have opened possibilities for adapting a commercially available gas engine for large-scale power generation application, albeit with a loss of power to an extent of 20–30 per cent. This loss in power is compensated to a much larger extent by the way toxic emissions are reduced; these technologies generate smaller amounts of toxic gases (low NOx and almost zero SOx), being zero for greenhouse gas (GHG).
Collision stage reconstruction in traffic accidents: Sensitivity analysis
Authors: Vangi D
Published: July 2005

The reconstruction approach is typically a process in which the effects (positions of vehicles at rest, various traces, permanent deformation, etc.) are examined to determine the causes (positions, velocities, acceleration of vehicles and occupants, etc.), and is in general numerically ill-conditioned, with the consequence that minor disturbance in the input data can produce broad variations in the final results. Since the input data and the parameters necessary for utilizing the physical models are known or estimated only with a certain degree of uncertainty, it follows that, for a given accident, substantially different scenarios may be envisaged. In this article, sensitivity to uncertainty in the input data for reconstructing traffic accidents is analysed. The effect of redundant data on calculation is analysed and parameters useful for identifying the data having the greatest effect on error propagation are indicated, for the purpose of reducing dispersion in the results.
Analysis of an in-line engine crankshaft under the firing condition
Authors: Aminudin B A , Oh Jae-Eung , Lee Jung Yoon
Published: July 2005

The paper presents a method for analysis of the mechanical behaviour of a crankshaft in a four-cylinder internal combustion engine. The purpose of the analysis was to study the characteristics of the shaft in which the pin and arm parts were assumed to have a uniform section in order to simplify the modal analysis. The results of the natural frequency transfer function and mode shape were compared with those obtained by experimental work. The results obtained from the comparison showed good agreement with each other and consequently verified the analysis model. Furthermore, a prediction of crankshaft characteristics under the firing condition, by using the model, was performed. The study describes a new method for analysing the dynamic behaviour of crankshaft vibrations in the frequency domain based on the initial firing stages. The new method used root mean square values to calculate the energy at each bearing journal and balancer shape modification under the operating conditions.
Measurement of reverberation time of a passenger car utilizing the wavelet filter bank
Authors: Lee Sang-Kwon , Yu Dong-June
Published: July 2005

A few researchers have tried to find the measurement of the reverberation time of a passenger car. However, this has proved to be extremely difficult because the reverberation time of a passenger car is too short to measure using the traditional bandpass filter. If the reverberation time is very short, the product of the reverberation time ( T) and the bandwidth ( B) of the traditional bandpass filter is very small. The low level of the product BT required for the measurement of the reverberation time using the traditional bandpass filter is 16. In order to overcome this problem, the wavelet filter bank has been developed. In the paper, this new wavelet filter is employed to measure the reverberation times of five different classes of passenger car. The low level of the product BT required for the measurement of reverberation time using the wavelet filter is 4. Therefore, it was possible to measure the reverberation times of five passenger cars successfully using the new wavelet filter bank. It is found that the reverberation times measured in most passenger cars are around 0.04. It is a very short reverberation time compared with those of general acoustic rooms like a concert hall.
A comparison of braking and differential control of road vehicle yaw-sideslip dynamics
Authors: Hancock M J , Williams R A , Gordon T J , Best M C
Published: July 2005

Two actuation mechanisms are considered for the comparison of performance capabilities in improving the yaw-sideslip handling characteristics of a road vehicle. Yaw moments are generated either by the use of single-wheel braking or via driveline torque distribution using an overdriven active rear differential. For consistency, a fixed reference vehicle system is used, and the two controllers are synthesized via a single design methodology. Performance measures relate to both open-loop and closed-loop driving demands, and include both on-centre and limit handling manoeuvres.
Cylinder head metal temperature control - a proof of concept study
Authors: Brace C J , Hawley J G , Vagenas A , Joyce S
Published: July 2005

A proof-of-concept study is reported that demonstrates the potential for cylinder head metal temperature control using liquid jets. Rig-based experiments have highlighted the potential benefits of actively controlled cooling jets. The rig-based work has been extended to a vehicle evaluation, and exhaust valve bridge temperature control has been demonstrated using a simple control strategy.
Load impact on railway track due to unsupported sleepers
Authors: Lundqvist A , Dahlberg T
Published: July 2005

Ballasted railway tracks will settle as a result of permanent deformations in the ballast and in the underlying material layers. The settlement is caused by the repeated traffic loading and the severity of the settlement depends on the quality and the behaviour of the ballast, the sub-ballast, and the subgrade.

As the behaviour of the material is not exactly the same under all sleepers, and since the loading of the track is irregular, the amount of settlement will differ from one sleeper to another. A result of this is that the sleepers are not always fully supported, and some sleepers may even become completely unsupported (voided). A gap appears between the sleeper and the ballast bed. As soon as the track geometry starts to deteriorate, the variations of the train/track interaction force increase, and this speeds up the track deterioration rate.

This paper presents a computer model by which the dynamic train/track interaction can be simulated. The influence of one or several voided sleepers on the train/track interaction force and on the track dynamics is investigated. Track settlement due to hanging sleeper(s) is discussed.
Designing of railway wheels. Part 2: Comparison of numerical analysis and experimental research
Authors: Sitarz M , Sladkowski A , Bizoń K , Chruzik K
Published: July 2005

Current design process can be simplified and accelerated, if computer simulation based on finite element method (FEM) is used. FEM numerical calculations of different wheels of railway wheelsets are investigated in the Department of Railway Engineering. The justification for undertaking this issue is that there is no methodology in the design of railway wheelsets both in Poland and abroad. In order to assess the calculation model, experimental tests of static loads (due to carriage weight) and thermal loads (due to braking) have been run. The results of these tests have been compared with the results of numerical analysis. The proposed calculation model has been compared with the results of test stand investigation. Comparison of the results has confirmed the correctness of the proposed discrete model and calculation algorithm.

In the framework of the common scientific-didactic projects of Railway Engineering Department and Central Rail Research Institute in Moscow and producer of railway wheelsets-BONATRANS a.s. in Bohumin (Czech Republic), the method was worked out, and the experimental researches were conducted on specialists certified stands for railway wheelset researches (Sitarz, M., Bizoń, K., and Chruzik, K. Numerical calculations reckonings of railway wheel sets. W: Scientific Proceedings of Riga Technical University, 2002, str 84-89, Sladkowski, A., Bizoń, K., and Chruzik, K. Porównanie wyników analizy MES z wynikami pomiarów tensometrycznych deformacji kól kolejowych zestawów kolowych, Zeszyty Naukowe Katedry Mechaniki Stosowanej nr 18/2002, Gliwice, 2002, str 397-402, Zima, R., Bizoń, K., Chruzik, K. Badania teoretyczne i eksperymentalne kól kolejowych zestawów kolowych, W: XLII Sympozjon ‘Modelowanie w mechanice’, Wisla, 2003).