bluuebunny/crossref_metadata_2025 huggingface dataset:
Tightening the net: children, community, and control
Authors: James Adrian L. , James Allison
Published: July 2002

The recent move to revitalize social democracy in the UK under the New Labour government, explored by Giddens as ‘the Third Way’, embraces many of Etzioni's ideas on communitarianism. The principles that emerge from these political philosophies, such as the involvement of local communities in policy consultations and implementation, have largely been welcomed as a reflection of the aim of revitalizing civic society in the context of a range of social policies. It is argued, however, that for children, contrary to this general trend, many of these policies represent attempts to increase the social control of children. Their effect has been to restrict children's agency and their rights, rather than to increase their participation as citizens, and thus, in spite of the requirements of the UN Convention on the Rights of the Child, children continue to be marginalized.
Critical realism and the dialectic1
Authors: Roberts John Michael
Published: July 2002

A prominent strand within both sociological and social theory has been concerned to develop a ‘systems approach’ with which to explore social life. One of the most original contributions to a systems approach has arisen within critical realism. In particular critical realism demonstrates that it is possible to abstract the causal powers of different objects of analysis to examine their interaction within concrete and contingent ‘open systems’. The recent dialectical turn of critical realism develops this systems approach in a much more rigorous manner. However, in this paper I argue that the (dialectical) critical realist mode of abstraction ultimately fails to embed concepts and categories internally within the specific ideological and historical forms of social relations. Or rather, critical realists do not seek to develop concepts that reflect the self‐movement of a historical and contradictory essence. This self‐movement is what I prefer to call a ‘system’. Consequently critical realists are led to separate method from system in theory construction and such a separation leads to a problematic dualist mode of theorizing. I make these observations from a Hegelian–Marxist position.
Thinking styles, self‐esteem, and extracurricular experiences
Authors: Zhang Li‐fang
Published: July 2002

This study had two objectives. The first was to examine the relationship between thinking styles and self‐esteem. The second objective was to investigate the relationship of the participants' extracurricular experiences to both thinking styles and self‐esteem. Seven‐hundred and ninety‐four university students from Hong Kong participated in the study. Participants responded to the Thinking Styles Inventory (Sternberg & Wagner, 1992) and the Self‐Esteem Inventory (Adult Form, Coopersmith, 1981) as well as to a questionnaire designed to elicit both personal and situational characteristics. It was found that thinking styles and self‐esteem are statistically related. Meanwhile, both thinking styles and self‐esteem are statistically related to the participants' extracurricular experiences. Implications of these findings for teachers are discussed.
Age and gender invariance of self‐concept factor structure: An investigation of a newly developed Chinese self‐concept instrument
Authors: Cheng Christopher H.K. , Watkins David
Published: July 2002

A new instrument, the Chinese Adolescent Self‐Esteem Scales (CASES), was developed to measure the self‐concepts of the young people in Hong Kong in seven aspects: social, academic, appearance, moral, family, physical/sport, and general self‐esteem. LISREL procedures were utilized to test the extent of factorial invariance for age and gender based on the responses to CASES of 551 Hong Kong adolescents. It was found that CASES possesses the necessary invariance properties for between‐group measurement in terms of the number and pattern of the underlying factors, item factor loadings, and inter‐factor relations, but not in terms of item uniqueness. Implications of these findings are discussed in terms of the use of CASES and of empirical support for the equivalence of self‐concept factor structure for age and gender groups for both Western and non‐Western adolescents.
Gender and birth order as determinants of parental behaviour
Authors: Keller Heidi , Zach Ulrike
Published: July 2002

This study analyses the effect of gender and birth order of fifty-eight 3-month-old first- and laterborn boys and girls on parental treatment. Presence of parents, maternal primary care, and maternal and paternal facial exchange with the baby were assessed during videotaped observation sessions equivalent to a full day. The data reveal a sound birth rank effect, indicating that firstborns are preferred over laterborns in several respects: presence of mothers, presence of fathers, and father’s face-to-face behaviour when the mother is also present. With respect to gender differences, mothers prefer their daughters in terms of presence and primary care. Fathers prefer their sons in terms of presence. Unexpectedly, fathers prefer their daughters in terms of face-to-face exchange. The social context of fathers’ and mothers’ joint presence reveals the only interaction effect between gender and birth order with the preference of firstborn boys. The findings are related to previous research results as well as evolutionary considerations about parental investment.
Lifespan personality development: Self-organising goal-oriented agents and developmental outcome
Authors: van Lieshout Cornelis F.M.
Published: July 2002

Several historical trends are enumerated that preceded contemporary discussions concerning the development of personality dimensions, personality types, and the person as a self-organising goal-oriented agent. For description of personality across the life course, the big-five personality dimensions are related to similar dimensions in temperament. For a proper understanding of the person as an active agent in personality development, a model for personality functioning is proposed that integrates elements of descriptive research on personality and temperament with theoretical views on personality and temperament functioning, that is, Block and Block’s (1980) views on the curvilinear relation between ego-control and ego-resiliency and Rothbart’s (1989) ideas on the distinction between reactivity and self-regulation. Typological personality studies are related to this model for personality functioning. Finally, personality development across the life course is related to the development of four developmental domains (i.e., interpersonal, achievement, self-concept, and creative domains).
Preference for diversity in competitive and cooperative contexts: A study of American and Japanese children and adolescents
Authors: Crystal David S. , Watanabe Hirozumi , Chen Ru San
Published: July 2002

This study examined preferences and explanations for wanting to be in a same-versus mixedachievement classroom, and in a group of peers with similar versus dissimilar interests and hobbies on a school trip among 5th, 8th, and 11th graders in Detroit and Matsuyama, Japan. Choice of the diverse environment varied by context, location, and grade level. Across contexts, preference for diversity tended to decrease among Detroit students, and increase among Matsuyama students with age. Additionally, students in Detroit were more likely than their peers in Matsuyama to give abilitybased and activity-related explanations; students in Matsuyama were more likely than students in Detroit to give mastery-based and cognitive-related explanations. Results are discussed in terms of social comparison theory.
Collaborative recall in married and unacquainted dyads
Authors: Gould Odette N. , Osborn Christopher , Krein Heather , Mortenson Michelle
Published: July 2002

Thirty younger couples between the ages of 19 and 36 ( M = 26.0, SD = 3.5) and thirty older couples between the ages of 56 and 85 ( M = 67.4, SD = 5.3) were tested on story recall, word recall, and a referential naming task. Each individual worked with the spouse and with a stranger of the other gender so that collaborative performance could be compared between familiar and unfamiliar dyads. Although participants anticipated that higher levels of recall performance would be obtained when they worked with a familiar partner, this expectation was not supported. Older men, but not older women recalled less information than younger adults. Younger dyads were found to be more efficient communicators than older dyads in the referential naming task.
Dealed out? Welfare to Work and Social Exclusion
Authors: Smith David
Published: July 2002

“Social exclusion” has increasingly replaced the term “underclass” in social policy debates. Regardless of changes in terminology many of the assumptions that informed the underclass debate remain. These focus on the role of cultural values in transmitting dependent modes of behaviour that have a corrosive impact on the work ethic of the poor. This article begin s by exploring the government's current conceptualisation of “social exclusion” as exclusion from paid employment an d how this has shaped the appropriate policy response. Following from this, the article will present ethnographic research that examines the responses of a sample of residents on a South London estate to the economic insecurities that they face. These insecurities are intensified by an increasingly coercive welfare system that emphasises “supply side” measures as a panacea for social exclusion. As previous field studies have indicated, man y have developed alternative solution s to economic marginality (MacDonald, 1994). At a situational level these may appear more attractive than the more formal routes currently offered. While broadly supportive of the promotion of education and training policies, many felt that these objectives are frequently compromised by more immediate concerns which are located in the respondent's perceptions of social exclusion. From this perspective, such notions may differ markedly from the rather limited version of “social exclusion” that is currently guiding the direction of welfare reform, suggesting the need for a broader definition of social exclusion that en compasses the standards an d lifestyles of the surrounding community (Townsend, 1979).
Marijuana Use Among the Adolescent Children of High‐Risk Drug‐Abusing Fathers
Authors: Brook David W. , Brook Judith S. , Richter Linda , Whiteman Martin , Arencibia‐Mireles Orlando , Masci Joseph R.
Published: July 2002

This study examines marijuana use among children of male drug abusers. Subjects were 83 African‐American and European‐American male drug abusers, of whom the majority were injection drug users, and their children. Thirty‐one of the fathers were HIV‐positive and 52 were HIV‐negative. Using logistic regression analyses, we explored cross‐sectionally the relationship between four psychosocial domains (ie, paternal attributes, adolescent problem behaviors, father‐adolescent relations, and environment) and adolescent marijuana use. The father's use of illegal drugs and his failure to cope adaptively predicted adolescent marijuana use, while a close father‐child bond predicted less adolescent marijuana use. Adolescent problem behaviors predicted an increased likelihood of marijuana use. Furthermore, hierarchical regression analysis demonstrated that the adolescent's problem behavior mediated the associations between both the father‐adolescent relationship and environmental factors with adolescent marijuana use. Reducing the risk factors and enhancing the protective factors within each of the domains could help reduce marijuana use among the adolescent children of drug‐abusing fathers. Moreover, if a father is a drug abuser, it is important to help him establish a close bond with his child in order to help attenuate the influence of his drug use on the child's marijuana use.
The nation and the South in the work of Rosario Romeo: A debate between John Dickie, Lucy Riall and Giuseppe Galasso: The idea of nation in Romeo
Authors: Dickie John , Riall Lucy , Galasso Giuseppe
Published: July 2002

The last seven or eight years have brought a flood of printer's ink dedicated to the issue of national identity in Italy. At the same time, the new political forces that have emerged since Tangentopoli have all, in various ways, contributed to the re-emergence of patriotism in the language of the public sphere. What would Rosario Romeo have said about this new cultural and political climate? How would he have sought to intervene? It seems likely that he would have turned his famously acerbic critical intelligence on many of the volumes published. A signi. cant number of them merely offer versions of the same old pathologizing version of Italian history, or even, ahistorically, of the Italian national character. All the Sicilian historian would have to do would be to dust off his criticisms of those Anglo-American and Marxist historians who portrayed Italy, in his view, as having had the ‘wrong’ history, of having certain aboriginal defects.
Efficacy of a parent‐implemented early language intervention based on collaborative consultation
Authors: Iacono Teresa A. , Chan Jeff B. , Waring Rebecca E.
Published: July 2002

A group of five preschool children with developmental disability and their mothers participated in a study into the efficacy of a parent‐implemented language intervention. Each parent was included in the team as a consultee, with a speech pathologist and special educator acting as consultants within a collaborative consultation process. Treatment for each child was developed using this process, with specific strategies to increase language production skills decided by the team. Strategies were used within an interactive model of early language intervention. The effectiveness of treatment was determined within a multiple baseline design. For three children, the impact of treatment was evident, but the results were not replicated for the other two children. Descriptive analysis of mothers' communicative behaviours indicated that, following treatment, they tended to direct more utterances to their children, used more models, fewer questions and directives, and more (although limited) teaching strategies.
When is a velar an alveolar? Evidence supporting a revised psycholinguistic model of speech production in children
Authors: Hewlett Nigel , Gibbon Fiona , Cohen‐McKenzie Wendy
Published: July 2002

Speech data from a single child with a phonological impairment were analysed with a view to assessing the influence of utterance mode (spontaneous vs. confrontation naming vs. repetition), lexical status (word vs. non‐word) and phonological context (voicing status and position in word) on the accuracy of production of velar targets. Under these conditions, accuracy was found to vary between ‘correct’ velar and ‘incorrect’ alveolar place of articulation. First, accuracy increased over four conditions, from spontaneous speech to confrontation naming to real word repetition to non‐word repetition. Second, there was a higher incidence of correct velar targets in initial than final position in the word, and a higher incidence of correct /k/ targets than /g/ targets. These findings are discussed in relation to a proposed model of child speech production, the configuration of which borrows heavily from similar models described recently in the literature. The model attempts to explain how a child represents and processes word‐forms, and over time revises their pronunciation. The explanation offered for these findings entails a claim that speech articulations are concerned directly with reproducing perceptual phenomena and that their ability to do so accurately may be constrained by processing load.
ADP-Ribosylation Factor 6 Regulates a Novel Plasma Membrane Recycling Pathway
Authors: Radhakrishna Harish , Donaldson Julie G.
Published: July 2002

ADP-ribosylation factor (ARF) 6 localizes to the plasma membrane (PM) in its GTP state and to a tubulovesicular compartment in its GDP state in HeLa cells that express wild-type or mutant forms of this GTPase. Aluminum fluoride (AlF) treatment of ARF6-transfected cells redistributes ARF6 to the PM and stimulates the formation of actin-rich surface protrusions. Here we show that cytochalasin D (CD) treatment inhibited formation of the AlF-induced protrusions and shifted the distribution of ARF6 to a tubular membrane compartment emanating from the juxtanuclear region of cells, which resembled the compartment where the GTP-binding defective mutant of ARF6 localized. This membrane compartment was distinct from transferrin-positive endosomes, could be detected in the absence of ARF6 overexpression or CD treatment, and was accessible to loading by PM proteins lacking clathrin/AP-2 cytoplasmic targeting sequences, such as the IL-2 receptor α subunit Tac. ARF6 and surface Tac moved into this compartment and back out to the PM in the absence of pharmacologic treatment. Whereas AlF treatment blocked internalization, CD treatment blocked the recycling of wild-type ARF6 and Tac back to the PM; these blocks were mimicked by expression of ARF6 mutants Q67L and T27N, which were predicted to be in either the GTP- or GDP-bound state, respectively. Thus, the ARF6 GTP cycle regulates this membrane traffic pathway. The delivery of ARF6 and membrane to defined sites along the PM may provide components necessary for remodeling the cell surface and the underlying actin cytoskeleton.
Nfat
Authors: Horsley Valerie , Pavlath Grace K.
Published: July 2002

The nuclear factor of activated T cells (NFAT) proteins are a family of transcription factors whose activation is controlled by calcineurin, a Ca2+-dependent phosphatase. Originally identified in T cells as inducers of cytokine gene expression, NFAT proteins play varied roles in cells outside of the immune system. This review addresses the recent data implicating NFAT in the control of gene expression influencing the development and adaptation of numerous mammalian cell types.
Development of Inflammatory Angiogenesis by Local Stimulation of Fas In Vivo
Authors: Biancone Luigi , Martino Antonella De , Orlandi Viviana , Conaldi Pier Giulio , Toniolo Antonio , Camussi Giovanni
Published: July 2002

Fas–Fas ligand interaction is thought to be a crucial mechanism in controlling lymphocyte expansion by inducing lymphocyte apoptosis. However, Fas is also broadly expressed on nonlymphoid cells, where its function in vivo remains to be determined. In this study, we describe the development of inflammatory angiogenesis induced by agonistic anti-Fas mAb Jo2 in a murine model where Matrigel is used as a vehicle for the delivery of mediators. The subcutaneous implants in mice of Matrigel containing mAb Jo2 became rapidly infiltrated by endothelial cells and by scattered monocytes and macrophages. After formation and canalization of new vessels, marked intravascular accumulation and extravasation of neutrophils were observed. Several mast cells were also detected in the inflammatory infiltrate. The phenomenon was dose and time dependent and required the presence of heparin. The dependency on activation of Fas is suggested by the observation that the inflammatory angiogenesis was restricted to the agonistic anti-Fas mAb and it was absent in lpr Fas-mutant mice. Apoptotic cells were not detectable at any time inside the implant or in the surrounding tissue, suggesting that angiogenesis and cell infiltration did not result from recruitment of phagocytes by apoptotic cells but rather by a stimulatory signal through Fas-engagement. These findings suggest a role for Fas–Fas ligand interaction in promoting local angiogenesis and inflammation.
Development of Eosinophilic Airway Inflammation and Airway Hyperresponsiveness in Mast Cell–deficient Mice
Authors: Takeda K. , Hamelmann E. , Joetham A. , Shultz L.D. , Larsen G.L. , Irvin C.G. , Gelfand E.W.
Published: July 2002

Mast cells are the main effector cells of immediate hypersensitivity and anaphylaxis. Their role in the development of allergen-induced airway hyperresponsiveness (AHR) is controversial and based on indirect evidence. To address these issues, mast cell–deficient mice (W/W  v) and their congenic littermates were sensitized to ovalbumin (OVA) by intraperitoneal injection and subsequently challenged with OVA via the airways. Comparison of OVA-specific immunoglobulin E (IgE) levels in the serum and numbers of eosinophils in bronchoalveolar lavage fluid or lung digests showed no differences between the two groups of mice. Further, measurements of airway resistance and dynamic compliance at baseline and after inhalation of methacholine were similar. These data indicate that mast cells or IgE–mast cell activation is not required for the development of eosinophilic inflammation and AHR in mice sensitized to allergen via the intraperitoneal route and challenged via the airways.
Positive Selection of Extrathymically Developed T Cells by Self-antigens
Authors: Yamada Hisakata , Ninomiya Toshiharu , Hashimoto Asako , Tamada Koji , Takimoto Hiroaki , Nomoto Kikuo
Published: July 2002

Most T cells develop through the thymus, where they undergo positive and negative selection. Some peripheral T cells are known to develop in the absence of thymus, but there is insufficient information about their selection. To analyze the selection of extrathymically developed T cells, we reconstituted thymectomized male or female recipient mice with bone marrow cells of mice transgenic for male H-Y antigen–specific T cell receptor (TCR). It was revealed that the T cells bearing self-antigen–specific TCR were not deleted in thymectomized male recipients. More importantly, the absence of H-Y antigen–specific T cells in thymectomized female recipients suggests positive selection of extrathymically developed T cells by the self-antigen. The extrathymically developed T cells in male mice expressed interleukin (IL)-2 receptor β chain (IL-2Rβ) and intermediate levels of CD3 (CD3int) but were natural killer cell (NK)1.1−. They rapidly produced interferon γ but not IL-4 after TCR cross-linking. Furthermore, a similar pattern of cytokine production was observed in CD3intIL-2Rβ+NK1.1− cells in normal mice which have been shown to develop extrathymically. These results suggest that extrathymically developed CD3intIL-2Rβ+NK1.1− cells in normal mice are also positively selected by self-antigens.
The Cyclin-dependent Kinase Cdk2 Regulates Thymocyte Apoptosis
Authors: Hakem Anne , Sasaki Takehiko , Kozieradzki Ivona , Penninger Josef M.
Published: July 2002

Aberrant activation of cell cycle molecules has been postulated to play a role in apoptosis (“catastrophic cell cycle”). Here we show that in noncycling developing thymocytes, the cyclin- dependent kinase Cdk2 is activated in response to all specific and nonspecific apoptotic stimuli tested, including peptide-specific thymocyte apoptosis. Cdk2 was found to function upstream of the tumor suppressor p53, transactivation of the death promoter Bax, alterations of mitochondrial permeability, Bcl-2, caspase activation, and caspase-dependent proteolytic cleavage of the retinoblastoma protein. Inhibition of Cdk2 completely protected thymocytes from apoptosis, mitochondrial changes, and caspase activation. These data provide the first evidence that Cdk2 activity is crucial for the induction of thymocyte apoptosis.
Cytotoxic T Lymphocyte–associated Antigen 4 (CTLA-4) Can Regulate Dendritic Cell–induced Activation and Cytotoxicity of CD8+ T Cells Independently of CD4+T Cell Help
Authors: McCoy Kathy D. , Hermans Ian F. , Henry Fraser J. , Le Gros Graham , Ronchese Franca
Published: July 2002

The mechanisms that regulate the strength and duration of CD8+ cytotoxic T cell activity determine the effectiveness of an antitumor immune response. To better understand the antitumor effects of anti-cytotoxic T lymphocyte–associated antigen 4 (CTLA-4) antibody treatment, we analyzed the effect of CTLA-4 signaling on CD8+ T cells in vitro and in vivo. In vitro, cross-linking of CTLA-4 on purified CD8+ T cells caused decreased proliferative responses to anti-CD3 stimulation and rapid loss of activation marker expression. In vivo, blockade of CTLA-4 by neutralizing anti–CTLA-4 mAb greatly enhanced the accumulation, activation, and cytotoxic activity of CD8+ T cells induced by immunization with Ag on dendritic cells (DC). This enhanced response did not require the expression of MHC class II molecules on DC or the presence of CD4+ T cells. These results demonstrate that CTLA-4 blockade is able to directly enhance the proliferation and activation of specific CD8+ T cells, indicating its potential for tumor immunotherapy even in situations in which CD4+ T cell help is limited or absent.
C-Abl Is Required for the Development of Hyperoxia-Induced Retinopathy
Authors: Nunes Irene , Higgins Rosemary D. , Zanetta Lucia , Shamamian Peter , Goff Stephen P.
Published: July 2002

The requirement for the nonreceptor tyrosine kinase c-abl in the pathogenesis of retinopathy of prematurity (ROP) was examined using the mouse model for ROP and c-abl–deficient mice. Hyperoxia-induced retinal neovascularization was observed in wild-type and heterozygous mice but animals that were homozygous null for c-abl did not develop a vasoproliferative retinopathy in response to hyperoxia. Two gene products, endothelin-1 (ET-1) and vascular endothelial growth factor (VEGF), have been implicated in the pathogenesis of ROP. The mRNA expression of ET-1 and VEGF was assessed in mice maintained in normoxia and in hyperoxia-exposed mice. ET-1 mRNA levels were unchanged in wild-type mice throughout the hyperoxia treatment, suggesting that ET-1 mRNA expression is not regulated by the increase in inspired oxygen. In wild-type mice maintained in room air, VEGF mRNA levels rose threefold from postnatal day 6 (P6) to P17. When wild-type mice were treated with the hyperoxia regimen, a fivefold decrease in VEGF mRNA expression was observed from P7 to P16. However, retinal VEGF expression in hyperoxia-treated homozygous null mice did not decrease and remained at control levels. These data suggest that c-abl is required for the hyperoxia-induced retinal neovascularization and hyperoxia-induced decrease in VEGF mRNA levels.
Polynomials with small Mahler measure
Authors: Mossinghoff Michael
Published: July 2002

We describe several searches for polynomials with integer coefficients and small Mahler measure. We describe the algorithm used to test Mahler measures. We determine all polynomials with degree at most 24 and Mahler measure less than

1.3
1.3

, test all reciprocal and antireciprocal polynomials with height 1 and degree at most 40, and check certain sparse polynomials with height 1 and degree as large as 181. We find a new limit point of Mahler measures near

1.309
1.309

, four new Salem numbers less than

1.3
1.3

, and many new polynomials with small Mahler measure. None has measure smaller than that of Lehmer’s degree 10 polynomial.
Separation of semialgebraic sets
Authors: Acquistapace F. , Andradas C. , Broglia F.
Published: July 2002

In this paper we study the problem of deciding whether two disjoint semialgebraic sets of an algebraic variety over

R

\mathbb R

are separable by a polynomial. For that we isolate a dense subfamily of Spaces of Orderings, named Geometric, which suffice to test separation and that reduce the problem to the study of the behaviour of the semialgebraic sets in their boundary. Then we derive several characterizations for the generic separation, among which there is a Geometric Criterion that can be tested algorithmically. Finally we show how to check recursively whether we can pass from generic separation to separation, obtaining a decision procedure for solving the problem.
Design and implementation of a CORBA-based genome mapping system prototype.
Authors: Hu J , Mungall C , Nicholson D , Archibald A L
Published: July 2002

MOTIVATION: CORBA (Common Object Request Broker Architecture), as an open standard, is considered to be a good solution for the development and deployment of applications in distributed heterogeneous environments. This technology can be applied in the bioinformatics area to enhance utilization, management and interoperation between biological resources. RESULTS: This paper investigates issues in developing CORBA applications for genome mapping information systems in the Internet environment with emphasis on database connectivity and graphical user interfaces. The design and implementation of a CORBA prototype for an animal genome mapping database are described. AVAILABILITY: The prototype demonstration is available via: http://www.ri.bbsrc.ac.uk/ark_corba/. CONTACT: jian.hu@bbsrc.ac.uk
AFFIRMATIVE ACTION IN COLLEGE ADMISSIONS: EXAMINING LABOR MARKET EFFECTS OF FOUR ALTERNATIVE POLICIES
Authors: Wydick Bruce
Published: July 2002

A rancorous debate continues to rage over the use of affirmative action policies in college admissions. This article uses a simple signaling model to evaluate the labor market impacts of four types of affirmative action admissions policies. RacE‐based preferential policies and policies guaranteeing admission based on high school academic rank may induce discrimination in labor markets when there exists strong heterogeneity in socioeconomic disadvantage within the underrepresented minority group. Under such conditions, it may also be difficult to realize ethnic diversity with disadvantagE‐based preferential policies. The article argues instead for affirmative action policies emphasizing intensive college preparation for targeted groups.
Visual signalling by asymmetry: a review of perceptual processes
Authors: Swaddle John P.
Published: July 2002

Individual levels of asymmetry in traits that display fluctuating asymmetry could be used as visual signals of phenotypic (and perhaps genotypic) quality, as asymmetry can often be negatively related to fitness parameters. There are some data to support this hypothesis but the experimental protocols employed have commonly resulted in asymmetries far larger than those observed in nature. To date, there has been little consideration of the ability of animals to accurately discriminate small asymmetries (of the magnitude observed in the wild) from perfect symmetry. This is key to assessing the plausibility of the asymmetry-signalling hypothesis. Here, I review the perceptual processes that may lead to the discrimination of asymmetry and discuss a number of ecologically elevant factors that may influence asymmetry signalling. These include: signal orientation, distance of trait elements from the axis of symmetry, trait complexity, trait contrast and colour, and the behaviour of both signaller and receiver. I also discuss the evolution of symmetry preferences and make suggestions as to where researchers should focus attention to examine the generality of asymmetry-signalling theory. In highly developmentally stable signalling systems the magnitude of asymmetry may be too small to be detected accurately and reliably, hence asymmetry signalling is unlikely to have evolved in these situations.
Host factors influencing viral persistence
Authors: Thomsen Allan Randrup , Nansen Anneline , Andreasen Susanne Ørding , Wodarz Dominik , Christensen Jan Pravsgaard
Published: July 2002

With the aim of characterizing the antiviral immune response to a non–cytocidal virus, we studied the outcome of lymphocytic choriomeningitis virus infection in a number of gene knockout mouse strains. Two virus strains differing markedly in their capacity to spread and replicate inside the murine host were used. Our results reveal that very different outcomes may be observed depending on virus strain and immunocompetence of the host. Thus while CD4+cells are not critical during the initial phase of virus control, infectious virus reappear in mice lacking CD4+cells, B cells or CD40 ligand. Reappearance of virus is associated with impaired long–term CD8+T–cell mediated immune surveillance, and the time to virus resurgence is inversely correlated to the replication rate of the virus. Our studies also reveal that interferon–γ is a central cytokine, and depending on the rate of virus replication, mice lacking the ability to produce interferon–γ– may develop either a severe, mostly fatal, T–cell mediated wasting syndrome or a chronic infection characterized by long–term coexistence of antiviral cytotoxic T lymphocytes and infectious virus. Mathematical modelling indicates that these different outcomes may be explained in relatively simple mathematical terms. This suggests that modelling may be used as a means to predict critical host and virus parameters. Therefore, combining mathematical modelling with precise, quantitative, in vivo analyses looks to be a promising approach in addressing central quantitative issues in immunobiology.
Integrating historical, clinical and molecular genetic data in order to explain the origin and virulence of the 1918 Spanish influenza virus
Authors: Taubenberger Jeffery K. , Reid Ann H. , Janczewski Thomas A. , Fanning Thomas G.
Published: July 2002

The Spanish influenza pandemic of 1918–1919 caused acute illness in 25–30% of the world'spopulation and resulted in the death of 40 million people. The complete genomic sequence of the 1918 influenza virus will be deduced using fixed and frozen tissues of 1918 influenza victims. Sequence and phylogenetic analyses of the complete 1918 haemagglutinin (HA) and neuraminidase (NA) genes show them to be the most avian–like of mammalian sequences and support the hypothesis that the pandemic virus contained surface protein–encoding genes derived from an avian influenza strain and that the 1918 virus is very similar to the common ancestor of human and classical swine H1N1 influenza strains. Neither the 1918 HA genes nor the NA genes possessed mutations that are known to increase tissue tropicity, which accounts for the virulence of other influenza strains such as A/WSN/33 or fowl plague viruses. The complete sequence of the nonstructural (NS) gene segment of the 1918 virus was deduced and tested for the hypothesis that the enhanced virulence in 1918 could have been due to type I interferon inhibition by the NS1 protein. The results from these experiments were inconclusive. Sequence analysis of the 1918 pandemic influenza virus is allowing us to test hypotheses as to the origin and virulence of this strain. This information should help to elucidate how pandemic influenza strains emerge and what genetic features contribute to their virulence.
Comparative measurements on a series of accelerators by the same vendor
Authors: Watts Ronald J.
Published: July 2002

A series of comparative measurements were conducted during a 12‐month period on a series of linear accelerators made by the same vendor. These measurements were conducted during acceptance and commissioning of six Varian model 2100C linear accelerators which had identical beam energies and beam modifiers. Nominal accelerating potentials, scatter measurements, depth doses, beam profiles, wedge and electron beam descriptors are presented. The results show highly similar beam parameters with observed variations being approximately equivalent to the precision of measurement. This similarity implies that a standard data set can be used to validate new commissioning data.
Einstein’s mistake and the cosmological constant
Authors: Harvey Alex , Schucking Engelbert
Published: July 2002

A brief history of the cosmological constant in the equations of general relativity is presented. Particular attention is paid to (a) a misunderstanding by Einstein of both its function as a repulsive force and new vacuum state rather than the relativistic analog of an exponential potential cutoff he thought he had introduced and to (b) a common misunderstanding of the function of the cosmological constant.
Angular scatter ultrasound imaging of wavelength scale targets
Authors: Lacefield James C. , von Ramm Olaf T.
Published: July 2002

A bistatic ultrasound imaging system is demonstrated that uses two 32-element linear phased array transducers oriented at an angle of 40 degrees to one another. The system simultaneously acquires and displays in real time one conventional backscatter image and one “angular scatter” image formed using side-scattered echoes from the same B-mode sector region. Experiments are presented that show differences in the magnitudes of backscatter and angular scatter signals acquired from three nylon monofilaments with diameters less than one wavelength and from soft tissue structures in vivo. The relative magnitudes of angular scatter signals from the monofilaments are qualitatively consistent with a theoretical analysis of acoustic scattering from elastic cylinders. Larger tissue features are more clearly defined in angular scatter images. This result is attributed to the orientation of specularly reflecting surfaces and the expected influence of scattering angle on the system’s sensitivity to different scatterer spacings.
Reducing seat dip attenuation
Authors: Davies W. J. , Cox T. J.
Published: July 2002

Strategies for reducing seat dip attenuation in concert halls are considered. It is shown that the dip is established 4 ms after the direct sound from the stage arrives at the listener. Sound scattered from the seats and floor is the main cause of the dip. By controlling these very early reflections the attenuation can be reduced to below its subjective threshold. With this in mind, changes to the shape and impedance of the seats and floor are trialed using a boundary element model and a physical scale model. It is found that the seat dip effect can be rendered inaudible by introducing a 1-m pit under the seats. Smaller improvements are produced by changing the impedance of the seat squab.
Numerical modeling of the spectral broadening of sodar echoes by winds perpendicular to the axis of a finite beamwidth antenna
Authors: Quintarelli Frank , Bergstrom Andreas
Published: July 2002

A simple model for determining the amount of spectral broadening in acoustic sounder echoes caused by winds traveling perpendicular to the antenna beam is presented. Key features of the model are that the wind profile is described by an analytic function and the antenna radiation pattern is included in the calculations. The model was restricted to the situation where the antenna was aligned in the vertical direction and the winds were horizontal. The effects of refraction by temperature and wind velocity gradients were neglected. The radiation pattern used in the model was the sinc(θ) or sin(θ)/θ function. The wind profiles which were used were a constant windspeed between the antenna and the scattering height, a profile where the windspeed increases linearly with height, and a logarithmic profile. Here, the amount of spectral broadening or spectral width of the echo is calculated by treating the amplitude spectrum of the echo as a probability distribution and determining the standard deviation of this distribution. It was found that the relationship between the standard deviation of the echo, σ, and windspeed, u, was closely described by a linear relationship, σ=Bu, with the value of B ranging from 0.05 to 0.08 for the situations modeled here. Observational data are presented. The data were obtained with a sounder whose radiation pattern was approximated with the sinc function. The observed relationship between σ, and u, was essentially linear, agreeing favorably with the model predictions; however, the value of the proportionality constant B was 0.04. A possible explanation for this is that the radiation pattern for the antenna may have been underestimated since the effects of the sound absorbing shielding surrounding the antenna are unknown.
Fundamental azimuthal modes of a constricted annular resonator: Theory and measurement
Authors: Muehleisen Ralph T. , Atchley Anthony A.
Published: July 2002

The fundamental azimuthal modes of a constricted annular resonator are investigated. It is found that a given mode of an unconstricted resonator splits into two separate modes in the constricted resonator. One mode is of a higher frequency and has a pressure antinode centered in the constricted region. The other mode is of a lower frequency and has a pressure node centered in the constricted region. The resonance frequency of the higher-frequency modes increases linearly with a decrease in the constricted to unconstricted area ratio, whereas the lower frequency drops nonlinearly. Measurements and theory match to within 0.5% when end corrections and thermo-viscous losses are included in the system model. It was found that end correction impedances derived by mode-matching techniques were the only ones accurate enough to match the measurements and computation to within the error bounds.
Boundary effect of a viscous fluid on a longitudinally vibrating bar: Theory and application
Authors: Darvennes Corinne M. , Pardue Sally J.
Published: July 2002

A theoretical model has been developed to represent the interaction of a bar in longitudinal vibration with its surrounding viscous fluid. This model was generated to better predict the length of timber piles used in bridge foundation. Experiments were performed with sand and with several water–glycerin mixtures surrounding an aluminum bar, showing a significant effect of the bounding material on the vibration characteristics of the bar. The viscous fluid was observed to lower the measured frequencies, indicating system mass loading, while the presence of the sand caused an upward shift in frequencies, indicating increased system stiffness. Hamilton’s principle was used to model the longitudinal bar motion with the fluid loading due to the viscous boundary, following the procedure of a known soil–bar interaction model. It was found that the fluid model gives an excellent prediction of the natural frequencies of the bar. The modal mass and damping were not predicted quite as accurately, but the fluid model offered a significant improvement over a simple bar model.
Experimental study of structure-borne sound transmission loss of mechanical joints
Authors: Feng Leping , Liu Mingshu , Nilsson Anders
Published: July 2002

A mechanical joint is one of the most effective ways to reduce the transmission of structure-borne sound. In order to increase the transmission loss, heavily damped joints are often used, which, in many cases, will reduce the structure integrity and hence can only be used in limited cases. In this study attention is focused on a type of resonant joint, i.e., a joint which will increase the transmission loss but will not reduce the structure integrity. The study is based on experiments in a one-dimensional structure. It is found that by adjusting the overlap of the joint, the transmission loss of 30 dB can be obtained at a certain frequency range without adding any dissipative materials. The mechanism of this high transmission loss is the cantilever-type resonance. The resonant frequency can be predicted precisely. The influence of extra dissipative material is investigated. The performance of the same joint in a finite structure is also examined by using the concept of vibrational insertion loss. When there is a certain damping in a finite system, a rather high insertion loss can still be achieved by using the above-mentioned joint, but the resonant frequency is shifted to higher end. It seems that the effective length of the cantilever is shortened by the finiteness.
The propagation of ultrasound within a gas jet
Authors: Hutchins D. A. , McIntyre C. S. , Choi D. W. , Billson D. R. , Robertson T. J.
Published: July 2002

A study is presented in which the directional characteristics of an ultrasonic signal have been modified due to propagation within an axial jet. The radiated ultrasonic field from a transducer positioned within the air jet has been studied at frequencies above 100 kHz for the first time. The effects of nozzle shape, nozzle diameter, and variations in air jet velocity and temperature have been investigated. At high air flow velocities, divergence of the ultrasonic beam was observed. This was attributed to the increased acoustic velocities in the direction of the flow. An effective waveguide was also demonstrated by cooling the air jet to below-ambient temperatures, so that the acoustic velocity in the air jet was lower than that in the surrounding ambient atmosphere. The result is likely to be of use in air-coupled ultrasonic materials inspection.
Sensitivity analysis of coupled structural-acoustic problems using perturbation techniques
Authors: Hahn Steven R. , Ferri Aldo A.
Published: July 2002

The analysis of acoustic radiation and scattering from submerged elastic structures is an important and challenging problem. Often, numerical solutions are hampered by the fact that the acoustic pressure field can be very sensitive to structural detail. In this paper, a procedure for obtaining the sensitivity of a structural-acoustic system to structural perturbations is presented. The theoretical development assumes a finite element description of the structure and a boundary element description of the fluid. The analysis includes full coupling between the fluid and the structure, and can accommodate both internal and/or external fluid regions. The types of perturbations are limited to those that do not alter the geometry of the wetted surface, but are otherwise completely general in nature. The technique is then applied to acoustic scattering from a cylindrical shell. Two perturbations are considered: A change in the shell thickness and a change in the elastic modulus. The effect of these structural perturbations on the surface pressure, surface normal velocity, and scattered pressure are examined for plane-wave scattering.
Acoustic scattering by nonmetallic and metallic cubes in the elastic resonance regime: Experimental measurements and combined finite element/boundary element modeling
Authors: Chinnery Paul A. , Zhang Jingdong , Humphrey Victor F.
Published: July 2002

The acoustic backscattering behavior of both nonmetallic (glass) and metallic (steel) cubes has been investigated over a wide frequency range where elastic resonances are important in determining the acoustic response of the cubes. A laboratory system incorporating a parametric array was used to make measurements between 20 and 200 kHz using cubes of side (l) 20 mm, and a combined finite element/boundary element code was used to numerically model scattering by the cubes. The frequency range covered corresponds to ka values up to 10, where a=l(3/4π)1/3 is a characteristic dimension of the cube. Results are presented for three scattering geometries involving incidence on to a face, an edge, and a corner. The backscattered form function differs greatly for the different geometries and is seen to depart significantly from that of a rigid cube when ka>5 due to the elastic resonances of the cube. The resonance contributions are clearly seen when the rigid background is subtracted from the elastic predictions.
Perceptual compensation for coarticulation by Japanese quail (Coturnix coturnix japonica)
Authors: Lotto Andrew J. , Kluender Keith R. , Holt Lori L.
Published: July 2002

When members of a series of synthesized stop consonants varying in third-formant (F3) characteristics and varying perceptually from /da/ to /ga/ are preceded by /al/, human listeners report hearing more /ga/ syllables than when the members of the series are preceded by /ar/. It has been suggested that this shift in identification is the result of specialized processes that compensate for acoustic consequences of coarticulation. To test the species-specificity of this perceptual phenomenon, data were collected from nonhuman animals in a syllable “labeling” task. Four Japanese quail (Coturnix coturnix japonica) were trained to peck a key differentially to identify clear /da/ and /ga/ exemplars. After training, ambiguous members of a /da/–/ga/ series were presented in the context of /al/ and /ar/ syllables. Pecking performance demonstrated a shift which coincided with data from humans. These results suggest that processes underlying “perceptual compensation for coarticulation” are species-general. In addition, the pattern of response behavior expressed is rather common across perceptual systems.