bluuebunny/crossref_metadata_2025 huggingface dataset:
Bayesian Estimation of Follower and Leader Vehicle Poses with a Virtual Trailer Link Model
Authors: Teck Chew Ng  , Adams Martin , Ibañez-Guzmán Javier
Published: December 2007

Autonomous Vehicle Following can be achieved if the poses of both the follower and leader vehicles are continuously estimated. This can be achieved by using a Bayesian estimation technique together with a virtual trailer link model. The advantage of such a model is that the follower vehicle will trail a virtual trailer, modeled as an attachment to the leader vehicle, instead of the leader vehicle itself, so that a safe spacing between the two vehicles is guaranteed. The key to a tractable solution to this vehicle following problem is the justifiable assumption that the pose of the follower vehicle is statistically independent of that of the leader. This assumption is valid when conditioned on the history of the follower vehicle's inputs and the sensor observations made by the follower vehicle. Hence, a factored solution to the joint estimate of the follower and leader poses can be formulated. Due to the factored solution, the pose of the follower vehicle is estimated separately using a recursive estimator. In a separate estimator, the poses of the virtual tailer and the leader vehicle are augmented in the tracking process of the leader vehicle. The aim is to command the follower vehicle to trail the estimated pose of the virtual trailer link model. The pose of the virtual trailer is computed with an on-board sensor mounted on the follower vehicle. A case study on the implementation of the proposed formulation, using an Extended Kalman Filter as the main estimator, is presented. First, simulation results are presented. To make the simulation results comparable to the actual system, the variances of sensor measurements are set according to real sensor data-sheet values. Various types of vehicle maneuver, such as straight paths and clothoids with left and right transition paths, are considered. Real experiments are also carried out in a car park. A comparison of the estimated paths and the best available ground truth is presented. The path deviations of the proposed system are also compared with similar systems in the literature.
The Use of Cognitive and Social Apprenticeship to Teach a Disciplinary Genre
Authors: Huiling Ding
Published: December 2007

This study reports about a yearlong study of the initiation of novice grant writers to the activity system of National Institutes of Health grant applications. It investigates the use of cognitive apprenticeship within writing classrooms and that of social apprenticeship in laboratories, programs, departments, and universities, which introduced students to the genre system of National Institutes of Health grant proposals and helped them in moving from peripheral participation to more central participation. While cognitive apprenticeship employs devices such as modeling, scaffolding, coaching, and collaboration to enhance learning in formal settings, social apprenticeship requires socialization, interaction, and collaboration with experts, colleagues, and peers in informal settings to acquire disciplinary knowledge and experiences. The study suggests that writing instructors should acknowledge and incorporate resources in other activity systems in which students participate, i.e., their laboratories and home departments, and teach genre systems rather than specific genres to better facilitate students' enculturation to activity systems of disciplinary discourse communities.
Advance Organizers in Advisory Reports
Authors: Lagerwerf Luuk , Cornelis Louise , de Geus Johannes , Jansen Phidias
Published: December 2007

According to research in educational psychology, advance organizers lead to better learning and recall of information. In this research, the authors explored advance organizers from a business perspective, where larger documents are read under time pressure. Graphic and verbal advance organizers were manipulated into six versions of an advisory report, read by 159 experienced professional readers in a between-subjects design. Their reading time was limited to encourage selective reading. The results show that graphic advance organizers facilitate selective reading, but they do not enhance recall. Verbal advance organizers introducing a problem enhance recall, and graphic advance organizers moderate the effects on both selective reading and recall.
“Building a Culture”: The Construction and Evolution of Venture Philanthropy as a New Organizational Field
Authors: Moody Michael
Published: December 2007

“Venture philanthropy” burst loudly onto the scene in the mid- to late 1990s, promoted as a way to revolutionize grantmaking. Today the field has been refined, and its proponents are more modest. The case of venture philanthropy provides insights into the construction and evolution of a “new” organizational field and “new” professional culture, topics that require further scholarly exploration. Qualitative research examining venture philanthropy organizations and their leaders is reported here. Findings suggest that although the dot-com boom was an important prompt, the construction and diffusion of the field depended on opinion leaders who strategically defined, legitimated, and advocated the new model. The fit with existing culture and institutionalization via networks were also important. Implementation difficulties and the business—nonprofit culture clash are among factors forcing evolution of the field. Several avenues for further research on this understudied field, and on other new fields and hybrid professional cultures, are suggested by these findings.
THE ITA PROBLEM: A ready-to-use simulation
Authors: Halleck Gene B.
Published: December 2007

This simulation probes what is known as the “foreign” teaching assistant problem. The “problem” can be found at large state universities in the United States where international graduate students are required to earn their scholarships by teaching undergraduate courses and arises because of a combination of issues, including the oral proficiency of the international teaching assistants (ITAs) and the xenophobic reactions to them by undergraduate students and their parents. The simulation probes the cross-cultural competence of all the stakeholders involved.
This Is Too Formal for Us...
Authors: Angouri Jo , Harwood Nigel
Published: December 2007

This article reports a case study of three multinational companies that work together in a consortium, focusing on intercompany and intracompany variation in writing products and processes. The authors discuss variation in two genres: meeting minutes and internal memos. Adopting a social constructionist, communities of practice (CofP) approach, they argue that the companies form overarching constellations of CofP. Although the participants broadly work with the same genres of written documents, the form of these documents varies according to the local context, audience, and purpose. The authors discuss the implications of their findings, with particular reference to the difficulty writers face when they make the transition from writing for one community of practice to writing for another.
Global, Regional, and Local Network Autocorrelation in the Standard Cross-Cultural Sample
Authors: Dow Malcolm M. , Eff E. Anthon
Published: December 2007

There is now considerable evidence in the cross-cultural literature that cultural networks need not be based strictly on spatial propinquity but may develop along other dimensions such as common language, religion, and levels of cultural complexity. In this article, the authors generate networks based on sociocultural distance metrics for these three network dimensions in addition to the usual geographical distance measure and a measure of overall ecological niche similarity. The authors report overall levels of autocorrelation for all five networks using 1,156 Standard Cross-Cultural Sample (SCCS) variables at the global level and for a subset of 422 variables within four regions. The extent to which cultural trait distributions appear to be influenced by combinations of network processes also are assessed. Results from an analysis based on a local autocorrelation statistic provide confirmation of the regional levels of autocorrelation within the SCCS data set.
The Individual Within a Condition: A Qualitative Study of Young People's Reflections on Being Treated for Anorexia Nervosa
Authors: Tierney Stephanie
Published: December 2007

BACKGROUND: Anorexia nervosa is a mental health problem that can seriously impede the physical, social, and psychological functioning of those who develop it. Unfortunately, outcome for this patient group, even after treatment, is not necessarily promising. OBJECTIVE: To explore the views of young people about being treated for anorexia. STUDY: DESIGN: Qualitative interviews were conducted with 10 adolescents. All interviews were recorded with participants' written consent and transcribed verbatim. A thematic analysis was applied to these data. RESULTS: Five themes were derived from the analysis: a) accessing appropriate care, b) balancing the physical and psychological, c) qualities required in professionals, d) help from nonprofessional routes, and e) perceived progress. CONCLUSIONS: Participants were clear about needing to be motivated to change. Practitioners can help by challenging patients in a nonconfrontational manner, treating them as individuals rather than cases of anorexia, and considering their psychosocial and physical functioning. J Am Psychiatr Nurses Assoc, 2008; 13(6), 368.-375. DOI: 10.1177/1078390307309215
Pilot Study of a Cognitive–Behavioral Group Intervention to Prevent Further Weight Gain in Hispanic Individuals With Schizophrenia
Authors: Weber Mary , Colon Marco , Nelson Monica
Published: December 2007

BACKGROUND: Obesity and type 2 diabetes are increasing significantly in the Hispanic population and in the Hispanic population with schizophrenia. In the Diabetes Prevention Project (DPP), cognitive—behavioral (CB) interventions were more effective in reducing weight and preventing diabetes. OBJECTIVE: To test a CB group intervention based on the DPP model among Hispanic individuals with schizophrenia on weight, body mass index (BMI), and waist—hip circumference (WH). STUDY DESIGN: Pilot study using a pre—post quasi-experimental design and convenience sample of 8 subjects from a public mental health clinic who met for 8 weekly group meetings. RESULTS: No significant differences in BMI, weight, or WH scores based on t -test results; the subjects' weight remained stable, there was a trend toward weight loss, and no one gained weight during the trial. CONCLUSIONS: No further weight gain is a finding that merits further research using a larger sample size and a randomized controlled design. J Am Psychiatr Nurses Assoc, 2008; 13(6), 353-359.
Bipolar Disorder and Weight Gain: A Multifactorial Assessment
Authors: Simmons-Alling Susan , Talley Sandra
Published: December 2007

Obesity is highly prevalent in persons with bipolar disorder. This results in increased physical morbidity and poorer psychiatric outcomes. Multiple variables have been identified as potentially responsible for the weight gain in these individuals. Efforts to use successful treatment strategies require an understanding of these variables and methods that clinicians and their clients can use to reduce or minimize these risk factors. This article will review the emerging findings related to primary and secondary weight gain in bipolar disorder. The sequelae of weight gain on psychiatric and medical morbidity will be discussed. Lastly, a model for nursing assessment will propose methods for modifying risk factors and encouraging healthy lifestyle changes. The goal is to improve this component of quality of life for persons with bipolar disorder. J Am Psychiatr Nurses Assoc, 2008; 13(6), 345-352. DOI: 10.1177/1078390307310145
Lessons Learned From Instructional Design Theory: an Application in Management Education
Authors: Burke Lisa A.
Published: December 2007

Given that many doctoral programs do not provide extensive training on how to present course information in the classroom, the current paper looks to educational psychology theory and research for guidance. Richard Mayer and others' copious empirical work on effective and ineffective instructional design, along with relevant research findings in cognitive science, are summarized and adapted to the management education context. The goal of this article is to enhance instructors' ability to effectively relay course material and to offer specific advice for how instructors can implement prior research findings.
Public Health Campaigns to Change Industry Practices That Damage Health: An Analysis of 12 Case Studies
Authors: Freudenberg Nicholas , Picard Bradley Sarah , Serrano Monica
Published: December 2007

Industry practices such as advertising, production of unsafe products, and efforts to defeat health legislation play a major role in current patterns of U.S. ill health. Changing these practices may be a promising strategy to promote health. The authors analyze 12 campaigns designed to modify the health-related practices of U.S. corporations in the alcohol, automobile, food and beverage, firearms, pharmaceutical, and tobacco industries. The objectives are to examine the interactions between advocacy campaigns and industry opponents; explore the roles of government, researchers, and media; and identify characteristics of campaigns that are effective in changing health-damaging practices. The authors compared campaigns that operate at different levels of organization and use different strategies. Findings suggest that many campaigns achieve policy or mobilization outcomes that may contribute to improved health; local campaigns may be more effective than national ones; and advocates frequently frame their campaigns on the themes of children's health and social justice.
Evaluating Psychosocial and Behavioral Mechanisms of Change in a Tailored Communication Intervention
Authors: Elder John P. , Ayala Guadalupe X. , Slymen Donald J. , Arredondo Elva M. , Campbell Nadia R.
Published: December 2007

This study examined the impact of a tailored nutrition intervention at 3 and 6 months postintervention. In all, 357 Latinas were randomly assigned to one of three conditions: (1) a control condition comprised of previously developed Spanish language targeted materials, (2) tailored print materials, or (3) tailored print materials accompanied by personalized dietary counseling via lay heath advisors ( promotoras). At 6 months postintervention, significant group by time interactions were observed on the dietary behavioral strategies scales. The promotora condition resulted in significant behavior change initially; however, receipt of tailored and control materials was instrumental in continued behavior change after intervention activities had ceased. Group main effects suggested that the promotora condition was superior at reducing barriers and improving family interactions supporting healthy behaviors. The promotora model is an effective method for changing important dietary behaviors and psychosocial determinants, but longer term behavior change is achievable with less expensive intervention methods.
Self-Efficacy Mediates the Relationship Between Depressive Symptoms and Medication Adherence Among Hypertensive African Americans
Authors: Schoenthaler Antoinette , Ogedegbe Gbenga , Allegrante John P.
Published: December 2007

Many studies have documented the negative effects of depression on adherence to recommended treatment; however, little is known about the mechanism underlying this relationship. Using the Kenny and Baron analytic framework of mediation, the authors assessed whether self-efficacy mediated the relationship between depression and medication adherence in 167 hypertensive African Americans followed in a primary care practice. Depressive symptoms are associated with poor medication adherence (β = .013, p = .036) and low self-efficacy (β = —.008, p = .023). Self-efficacy is negatively associated with medication adherence at follow-up (β = —.612, p < .001). The relationship between depressive symptoms and medication adherence becomes nonsignificant when controlling for self-efficacy (β = .010, p = .087). Implications for further examination into the mediating role of self-efficacy and the deleterious effect of depression on medication adherence are discussed.
The influences of parents, teachers, peers and other factors on students' motivation in music
Authors: Sichivitsa Veronica O.
Published: December 2007

This study examined influences of: parental support of music, previous musical experience, self-concept in music, teachers and peers, academic and social integration in music classes, and value of music on college nonmusic majors' intentions to continue music participation. An author-developed Choir Participation Survey was administered to 130 choir members at a large public university in the United States. The proposed path analytical model fitted data well and explained 42% ( p < .01) of variance in musical intentions. The analysis showed that students whose parents were involved in music and supportive of their children's musical participation developed better self-concepts in music, consequently felt more comfortable in choir academically and socially, valued music more, and as a result developed higher motivation to participate in various musical activities in the future. The strongest direct predictor of musical intentions was value of music (β = .65, p < .01).
To Know Me Now
Authors: Pfau Heidi
Published: December 2007

This article combines an autoethnography that was part of the author's graduate schoolwork with a `post-script' written six years later. The autoethnography assignment focused on the personal experience of the writer while illuminating social and cultural contexts. The article's first section recounts a conversation in which complex personal, social and political aspects of disability unfold. The dialogue becomes a springboard for examining research about blindness and rehabilitation. It also prompts self-reflection and an inner examination of individual choice as the author struggled to be seen as `more than her vision'. In the second section, the fluid contexts of knowledge and the knower are made explicit as meanings of `choice' and `living' are re-examined. The author considers the apparent contradiction of needing others to see vision loss and to look beyond it. She also considers her own assumptions about how others relate to disability.
A Day in the Life of a Hospital Social Worker
Authors: Wilder Craig Rita
Published: December 2007

Social workers have always used narratives in the service of their clients. Many of us spend half our days listening to stories and the other half repeating them in one form or another, whether in assessments, in advocating for services or for a more accurate understanding of a client's circumstances. While we excel at this kind of storytelling, we have been held back from using the narrative genre in telling our own story. That story is one that describes the intricacies and variety of social work practice as well as the uniqueness that distinguishes us from other helping professions. For hospital social workers, who have experienced profound change in recent years, it is especially important that we find innovative and interesting ways to convey a richer and deeper understanding and appreciation of our role. The genre of personal narrative allows us to do this in a voice suitable for the task. When narratives are used in this way they can be seen as a tool of advocacy for both ourselves and our clients (Chambon, 2004).
Crossing the Line
Authors: Martin Megan C.
Published: December 2007

This is an experimental piece that reports on findings from a research project conducted from September to December 2006 on the border between a neighborhood on the east side of Detroit (Jefferson Chalmers) and Grosse Pointe Park, Michigan. The project addresses the stark racial, economic, and physical divides between two proximate communities, and the way that the boundary line between these communities is enacted. Alter Road, serves as this real and infrequently crossed border. The physical barriers put in place to reinforce the imaginary line between East Detroit,1 and Grosse Pointe Park and the conditions on either side of the border are prominent themes. For social workers, understanding how and why bordering communities remain insular, and the effect of that segregation, is important in understanding human behavior and better appreciating the circumstances from which people come. This qualitative piece illustrates these issues through the eyes of a graduate social work student walking again and again across that boundary.
Relational Poetry
Authors: Witkin Stanley L
Published: December 2007

Relational poetry is a form of poetry inspired by social constructionism. A freestanding poem is responded to via an interweaving of a second poem within the lines of the first. The result is a new poem that is different than either one alone.
Television News in India
Authors: Cottle Simon , Rai Mugdha
Published: December 2007

The `communicative architecture' routinely organizing and delivering television news in India, as with television news internationally, exhibits far more complexity than conventional discourse and framing approaches to news study have thus far acknowledged or explored. The article argues that these communicative structures have direct bearing on debates about `democracy' in India's diverse and fractious polity. Drawing on wider positions of contemporary social and political theory, it is demonstrated how the `communicative frames' deployed by Indian broadcasters are consequential for the public deliberation and display of conflicts and cultures and we systematically compare these with the communicative frames deployed by television news in five other countries. The article identifies, maps and pursues into the production domain the repertoire of `communicative frames' characterizing Indian television news today and reveals important differences between the public broadcaster Doordarshan and the private network NDTV 24 × 7 as well as between Indian television news and television news internationally. On this basis, the study considers how the structures of television news communicatively and differentially embed `democracy'.
Indoleamine 2,3-dioxygenase is a critical regulator of acute graft-versus-host disease lethality
Authors: Jasperson Lisa K. , Bucher Christoph , Panoskaltsis-Mortari Angela , Taylor Patricia A. , Mellor Andrew L. , Munn David H. , Blazar Bruce R.
Published: December 2007

Graft-versus-host disease (GVHD) is initiated after activation of donor T cells by host antigen-presenting cells (APCs). The immunosuppressive enzyme indoleamine 2,3-dioxygenase (IDO) is expressed by APCs and parenchymal cells and is further inducible by inflammation. We investigated whether lethal conditioning and GVHD induce IDO and if IDO prevents tissue injury by suppressing immune responses at the induction site. We determined that IDO is a critical regulator of GVHD, most strikingly in the colon, where epithelial cells dramatically up-regulated IDO expression during GVHD. IDO−/− mice died more quickly from GVHD, displaying increased colonic inflammation and T-cell infiltration. GVHD protection was not mediated by control of T-cell proliferation, apoptosis, or effector mechanisms in lymphoid organs, nor did it require donor T regulatory cells. Instead, T cells in IDO−/− colons underwent increased proliferation and decreased apoptosis compared with their wild-type counterparts. This evidence suggests that IDO can act at the site of expression to decrease T-cell proliferation and survival, diminishing colonic inflammation and reducing disease severity. These studies are the first to identify a function for IDO in GVHD lethality and indicate that modulation of the IDO pathway may be an effective strategy for treatment of this disease.
Positional bias of general and tissue-specific regulatory motifs in mouse gene promoters
Authors: Bellora Nicolás , Farré Domènec , Albà M Mar
Published: December 2007

Background

The arrangement of regulatory motifs in gene promoters, or promoter architecture, is the result of mutation and selection processes that have operated over many millions of years. In mammals, tissue-specific transcriptional regulation is related to the presence of specific protein-interacting DNA motifs in gene promoters. However, little is known about the relative location and spacing of these motifs. To fill this gap, we have performed a systematic search for motifs that show significant bias at specific promoter locations in a large collection of housekeeping and tissue-specific genes.

Results

We observe that promoters driving housekeeping gene expression are enriched in particular motifs with strong positional bias, such as YY1, which are of little relevance in promoters driving tissue-specific expression. We also identify a large number of motifs that show positional bias in genes expressed in a highly tissue-specific manner. They include well-known tissue-specific motifs, such as HNF1 and HNF4 motifs in liver, kidney and small intestine, or RFX motifs in testis, as well as many potentially novel regulatory motifs. Based on this analysis, we provide predictions for 559 tissue-specific motifs in mouse gene promoters.

Conclusion

The study shows that motif positional bias is an important feature of mammalian proximal promoters and that it affects both general and tissue-specific motifs. Motif positional constraints define very distinct promoter architectures depending on breadth of expression and type of tissue.
Dimerisation of HIV-2 genomic RNA is linked to efficient RNA packaging, normal particle maturation and viral infectivity
Authors: L'Hernault Anne , Greatorex Jane S , Crowther R Anthony , Lever Andrew ML
Published: December 2007

Background

Retroviruses selectively encapsidate two copies of their genomic RNA, the Gag protein binding a specific RNA motif in the 5' UTR of the genome. In human immunodeficiency virus type 2 (HIV-2), the principal packaging signal (Psi) is upstream of the major splice donor and hence is present on all the viral RNA species. Cotranslational capture of the full length genome ensures specificity. HIV-2 RNA dimerisation is thought to occur at the dimer initiation site (DIS) located in stem-loop 1 (SL-1), downstream of the main packaging determinant. However, the HIV-2 packaging signal also contains a palindromic sequence (pal) involved in dimerisation. In this study, we analysed the role of the HIV-2 packaging signal in genomic RNA dimerisation in vivo and its implication in viral replication.

Results

Using a series of deletion and substitution mutants in SL-1 and the Psi region, we show that in fully infectious HIV-2, genomic RNA dimerisation is mediated by the palindrome pal. Mutation of the DIS had no effect on dimerisation or viral infectivity, while mutations in the packaging signal severely reduce both processes as well as RNA encapsidation. Electron micrographs of the Psi-deleted virions revealed a significant reduction in the proportion of mature particles and an increase in that of particles containing multiple cores.

Conclusion

In addition to its role in RNA encapsidation, the HIV-2 packaging signal contains a palindromic sequence that is critical for genomic RNA dimerisation. Encapsidation of a dimeric genome seems required for the production of infectious mature particles, and provides a promising therapeutic target.
Activation of HIV-1 expression and replication by cGMP dependent protein kinase type 1-β (PKG1β)
Authors: Lee Jia Hai , Yedavalli Venkat RK , Jeang Kuan-Teh
Published: December 2007

The effect of cGMP (cyclic GMP) dependent protein kinase 1-β (PKG1-β) and cGMP analogues on transcriptional activity and replication of human immunodeficiency virus type 1 (HIV-1) was investigated. Transfection of PKG1β expression plasmid increased expression from an HIV-1 LTR-reporter as well as from an infectious HIV-1 molecular clone, pNL4-3. Treatment of HIV-1 AD8-infected monocyte derived macrophages (MDMs) with cGMP agonists and cGMP antagonists caused respectively increased and decreased virus replication. These findings provide evidence that cGMP and PKG serve to regulate HIV-1 infection in human cells.
Phase I/II Study of Sequential Dose-Intensified Ifosfamide, Cisplatin, and Etoposide Plus Paclitaxel As Induction Chemotherapy for Poor Prognosis Germ Cell Tumors by the German Testicular Cancer Study Group
Authors: Hartmann Jörg T. , Gauler Thomas , Metzner Bernd , Gerl Arthur , Casper Jochen , Rick Oliver , Horger Marius , Schleicher Jan , Derigs Günter , Mayer-Steinacker Regine , Beyer Jörg , Kuczyk Markus A. , Bokemeyer Carsten
Published: December 2007

Purpose

To evaluate the feasibility and the toxicity of sequential, dose-intensified chemotherapy combined with paclitaxel plus peripheral blood–derived hematopoietic stem-cell support (PBSC) for patients with untreated metastatic germ cell tumors (GCTs) who have poor International Germ Cell Consensus Cancer Group prognostic features.

Patients and Methods

Paclitaxel was added to high-dose (HD) etoposide, ifosfamide, and cisplatin (VIP; etoposide 1,500 mg/m2, ifosfamide 10,000 mg/m2, and cisplatin 100 mg/m2; cumulative dose; days −6 through −2 per cycle) at three dose levels (135, 175, and 225 mg/m2) applied on day −6. Cycles were supported by PBSC and granulocyte colony-stimulating factor. One cycle of standard VIP was administered before start of HD-VIP plus paclitaxel cycles to collect autologous PBSC.

Results

Fifty-two of 53 patients receiving 152 cycles were assessable. As expected, myelosuppression was the major adverse effect. Median durations of leukocytes less than 1,000/μL and thrombocytes less than 25,000/μL were 6 and 4 days, respectively, independently of the dose of paclitaxel applied. WHO grade 2 neurotoxicity and grade 3 encephalopathy were observed in 5% of patients each. Other main adverse effects observed were stomatitis, diarrhea, and obstipation. Seventy-nine percent of patients achieved a favorable response to chemotherapy plus secondary surgery. After a median follow-up time of 41 months in surviving patients, the calculated 2- and 5-year survival rates were 77.6% (95% CI, 65.4% to 89.9%) and 75.2% (95% CI, 62.5% to 87.8%), respectively.

Conclusion

Dose-intensive, sequential HD-VIP plus paclitaxel up to a dose of 225 mg/m2 in patients with poor prognosis GCT is a feasible approach. The regimen warrants investigation for its therapeutic potential in an expanded cohort of poor prognosis GCT patients.
The zebrafish mutantlbk/vam6resembles human multisystemic disorders caused by aberrant trafficking of endosomal vesicles
Authors: Schonthaler Helia B. , Fleisch Valerie C. , Biehlmaier Oliver , Makhankov Yuri , Rinner Oliver , Bahadori Ronja , Geisler Robert , Schwarz Heinz , Neuhauss Stephan C. F. , Dahm Ralf
Published: December 2007

The trafficking of intracellular vesicles is essential for a number of cellular processes and defects in this process have been implicated in a wide range of human diseases. We identify the zebrafish mutant lbk as a novel model for such disorders. lbk displays hypopigmentation of skin melanocytes and the retinal pigment epithelium (RPE), an absence of iridophore reflections, defects in internal organs (liver, intestine) as well as functional defects in vision and the innate immune system (macrophages). Positional cloning, an allele screen, rescue experiments and morpholino knock-down reveal a mutation in the zebrafish orthologue of the vam6/vps39 gene. Vam6p is part of the HOPS complex, which is essential for vesicle tethering and fusion. Affected cells in the lbkRPE, liver, intestine and macrophages display increased numbers and enlarged intracellular vesicles. Physiological and behavioural analyses reveal severe defects in visual ability in lbk mutants. The present study provides the first phenotypic description of a lack of vam6 gene function in a multicellular organism. lbk shares many of the characteristics of human diseases and suggests a novel disease gene for pathologies associated with defective vesicle transport, including the arthrogryposis-renal dysfunction-cholestasis (ARC) syndrome, the Hermansky-Pudlak syndrome, the Chediak-Higashi syndrome and the Griscelli syndrome.
Drosophilaeggshell is patterned by sequential action of feedforward and feedback loops
Authors: Yakoby Nir , Lembong Jessica , Schüpbach Trudi , Shvartsman Stanislav Y.
Published: December 2007

During Drosophila oogenesis, patterning activities of the EGFR and Dpp pathways specify several subpopulations of the follicle cells that give rise to dorsal eggshell structures. The roof of dorsal eggshell appendages is formed by the follicle cells that express Broad (Br), a zinc-finger transcription factor regulated by both pathways. EGFR induces Br in the dorsal follicle cells. This inductive signal is overridden in the dorsal midline cells, which are exposed to high levels of EGFR activation, and in the anterior cells, by Dpp signaling. We show that the resulting changes in the Br pattern affect the expression of Dpp receptor thickveins(tkv), which is essential for Dpp signaling. By controlling tkv, Br controls Dpp signaling in late stages of oogenesis and, as a result, regulates its own repression in a negative-feedback loop. We synthesize these observations into a model, whereby the dynamics of Br expression are driven by the sequential action of feedforward and feedback loops. The feedforward loop controls the spatial pattern of Br expression,while the feedback loop modulates this pattern in time. This mechanism demonstrates how complex patterns of gene expression can emerge from simple inputs, through the interaction of regulatory network motifs.
Eomesodermin, a target gene of Pou4f2, is required for retinal ganglion cell and optic nerve development in the mouse
Authors: Mao Chai-An , Kiyama Takae , Pan Ping , Furuta Yasuhide , Hadjantonakis Anna-Katerina , Klein William H.
Published: December 2007

The mechanisms regulating retinal ganglion cell (RGC) development are crucial for retinogenesis and for the establishment of normal vision. However,these mechanisms are only vaguely understood. RGCs are the first neuronal lineage to segregate from pluripotent progenitors in the developing retina. As output neurons, RGCs display developmental features very distinct from those of the other retinal cell types. To better understand RGC development, we have previously constructed a gene regulatory network featuring a hierarchical cascade of transcription factors that ultimately controls the expression of downstream effector genes. This has revealed the existence of a Pou domain transcription factor, Pou4f2, that occupies a key node in the RGC gene regulatory network and that is essential for RGC differentiation. However,little is known about the genes that connect upstream regulatory genes, such as Pou4f2 with downstream effector genes responsible for RGC differentiation. The purpose of this study was to characterize the retinal function of eomesodermin (Eomes), a T-box transcription factor with previously unsuspected roles in retinogenesis. We show that Eomes is expressed in developing RGCs and is a mediator of Pou4f2 function. Pou4f2 directly regulates Eomes expression through a cis-regulatory element within a conserved retinal enhancer. Deleting Eomes in the developing retina causes defects reminiscent of those in Pou4f2-/-retinas. Moreover, myelin ensheathment in the optic nerves of Eomes-/- embryos is severely impaired, suggesting that Eomes regulates this process. We conclude that Eomes is a crucial regulator positioned immediately downstream of Pou4f2 and is required for RGC differentiation and optic nerve development.
FGF signals guide migration of mesenchymal cells, control skeletal morphogenesis and regulate gastrulation during sea urchin development
Authors: Röttinger Eric , Saudemont Alexandra , Duboc Véronique , Besnardeau Lydia , McClay David , Lepage Thierry
Published: December 2007

The sea urchin embryo is emerging as an attractive model to study morphogenetic processes such as directed migration of mesenchyme cells and cell sheet invagination, but surprisingly, few of the genes regulating these processes have yet been characterized. We present evidence that FGFA, the first FGF family member characterized in the sea urchin, regulates directed migration of mesenchyme cells, morphogenesis of the skeleton and gastrulation during early development. We found that at blastula stages, FGFA and a novel putative FGF receptor are expressed in a pattern that prefigures morphogenesis of the skeletogenic mesoderm and that suggests that FGFA is one of the elusive signals that guide migration of primary mesenchyme cells (PMCs). We first show that fgfA expression is correlated with abnormal migration and patterning of the PMCs following treatments that perturb specification of the ectoderm along the oral-aboral and animal-vegetal axes. Specification of the ectoderm initiated by Nodal is required to restrict fgfA to the lateral ectoderm, and in the absence of Nodal, fgfA is expressed ectopically throughout most of the ectoderm. Inhibition of either FGFA, FGFR1 or FGFR2 function severely affects morphogenesis of the skeleton. Furthermore,inhibition of FGFA and FGFR1 signaling dramatically delays invagination of the archenteron, prevents regionalization of the gut and abrogates formation of the stomodeum. We identified several genes acting downstream of fgfAin these processes, including the transcription factors pea3 and pax2/5/8 and the signaling molecule sprouty in the lateral ectoderm and SM30 and SM50 in the primary mesenchyme cells. This study identifies the FGF signaling pathway as an essential regulator of gastrulation and directed cell migration in the sea urchin embryo and as a key player in the gene regulatory network directing morphogenesis of the skeleton.
TheSf1-related nuclear hormone receptorHr39regulatesDrosophilafemale reproductive tract development and function
Authors: Allen Anna K. , Spradling Allan C.
Published: December 2007

The vertebrate nuclear hormone receptor steroidogenic factor 1 (SF1; NR5A1)controls reproductive development and regulates the transcription of steroid-modifying cytochrome P450 genes. We find that the SF1-related Drosophila nuclear hormone receptor HR39 is also essential for sexual development. In Hr39 mutant females, the sperm-storing spermathecae and glandular parovaria are absent or defective, causing sterility. Our results indicate that spermathecae and parovaria secrete reproductive tract proteins required for sperm maturation and function, like the mammalian epididymis and female reproductive tract. Hr39 controls the expression of specific cytochrome P450 genes and is required in females both to activate spermathecal secretion and repress male-specific courtship genes such as takeout. Thus, a pathway that, in vertebrates, controls sex-specific steroid hormone production, also mediates reproductive functions in an invertebrate. Our findings suggest that Drosophila can be used to model more aspects of mammalian reproductive biology than previously believed.
Structural optimization of an automotive door using the kriging interpolation method
Authors: Lee K-H , Kang D-H
Published: December 2007

Weight reduction of automobile components has been sought to achieve fuel efficiency and energy conservation. There are two approaches for weight reduction: use of materials lighter than steel and structural redesign. The latter has been performed by adopting hydroforming, tailor-welded blank (TWB) technology, optimization, etc. In this research, the kriging interpolation method and a simulated annealing algorithm are applied in the design of a front door made by TWB technology. The design variables were the thicknesses of the parts and the positions of the parting lines. A thickness set, considered as a candidate design of each part, is not arbitrarily determined, but selected from the thicknesses of standard products, and so it is a discrete set. This research presents the discrete and continuous structural optimization of an automotive door design.
A study of the simulation of a front-crash-induced rollover crash
Authors: Jiang C , Neal Sturgess C E
Published: December 2007

Computer-based simulation of rollover using MADYMO can assist in understanding the occupant and vehicle kinematics of these complex long-duration events, and the resulting occupant injuries. This study focused on the simulation of a front-crash-induced rollover event. A hybrid finite element (FE)-rigid body model of the vehicle was created to simulate the deformation during the impact and its influence on the following rollover event. This was used, together with a multi-body MADYMO model of a Hybrid III dummy, to evaluate the probability of head injury in the crash. Special attention was paid to the modelling of the suspension and tyres. Simulation results from both the FE model and the rigid body model were validated and evaluated. The results indicate that rollover simulations using MADYMO proved to be an efficient computer aided engineering (CAE) methodology. It is necessary to have a deformable FE front end for the vehicle to simulate this type of event accurately. The injury parameters from the simulation correlate well with the injury results from the crash report.
Developments in space debris mitigation policy and practices
Authors: Johnson N L
Published: December 2007

Since the American Institute of Aeronautics and Astronautics issued the first position paper on space debris 25 years ago, recognition of the threats posed by debris in Earth orbit and the need to act now to protect the future space environment have become widespread. This new awareness has been matched with positive actions by spacecraft and launch vehicle designers, manufacturers, and operators. As a result, a common set of space debris mitigation policies and practices has been forming at both the national and international levels.
Ionic Liquids Then and Now: From Solvents to Materials to Active Pharmaceutical Ingredients
Authors: Hough Whitney L , Rogers Robin D
Published: December 2007

Ionic liquids (ILs) have evolved from salts studied primarily for their physical properties (low melting salts which could be used as solvents) to tunable materials based upon the physical, chemical, and now even biological properties that can be introduced through either ion. In this perspective, we follow this interesting evolution with respect to our work in this growing field, and discuss possible future directions, such as the use of ILs as active pharmaceutical ingredients (APIs).
Studies on Two- and Three-Dimensional π-Conjugated Systems with Unique Structures and Properties
Authors: Komatsu Koichi
Published: December 2007

A series of two-dimensional, cyclic π-conjugated systems with the six-membered to eight-membered rings as well as polycyclic aromatic compounds and sulfur-containing compounds, which were fully surrounded by rigid bicyclic σ-frameworks, were synthesized and their structures and properties elucidated. This structural modification is characteristic to cause an elevation of the HOMO levels of neutral π-systems and to stabilize remarkably the corresponding cationic systems by both thermodynamic and kinetic effects. In contrast to annelation with a strain-free bicyclic system, such as bicyclo[2.2.2]octene, annelation with a more strained system, such as bicyclo[2.1.1]hexene, brings about a large bond fixation effect upon the cyclic π-system. Thus, π-conjugated systems with quite unusual electronic structures can be prepared by using combination of these structural modifications. As another example of unusual structure, a novel three-dimensional π-conjugated system, i.e., fullerene encapsulating molecular hydrogen, was synthesized from empty fullerene using organic reactions. This is taken as an entirely new approach to the endohedral fullerenes, of which the production has so far relied only on physical methods.
Evidence for Encaging Luminescent Guest Molecules in the Inner Cages of Zeolite Host
Authors: Kataoka Tomoharu , Mozer Attila J , Tsukahara Yasunori , Yamauchi Tomohisa , Wada Yuji
Published: December 2007

Clear evidence for encaging guest molecules in a host material was obtained for FAU-type zeolite containing fluorescein (FL) as a guest by employing the luminescence-quenching phenomenon of FL with C60. Whereas fluorescence of FL molecules adsorbed on the outer surface of the zeolite was effectively quenched as well as that in a homogeneous solution, that of the most FL molecules in the cages of the zeolite did not suffer from quenching by C60, giving clear evidence that FL molecules are located in the inner cages, which are inaccessible to C60. Only the fluorescence of the FL molecules located in the cages in the outermost unit cells of the zeolite was partially quenched. This partial quenching can be understood by considering the structure of the zeolite and the critical distance of electron transfer inducing the fluorescence quenching.
Cyano-Bridged Gadolinium–Tungstate Bimetallic One-Dimensional Chains with a Dimethylacetamide Ligand
Authors: Kosaka Wataru , Hashimoto Kazuhito , Ohkoshi Shin-ichi
Published: December 2007

Reaction of GdIII(NO)3·6H2O and (Bu3NH)3[WV(CN)8] (Bu3N = tributylamine) in N,N-dimethylacetamide (DMA) yielded two types of Gd–W bimetal assemblies with noncentrosymmetric crystal structures: GdIII(DMA)n[WV(CN)8] (n=6, 1; n=5, 2). X-ray single crystal analyses showed that 1 crystallizes in the monoclinic system of the Cc space group (a=12.6254(6) Å, b=16.8052(8) Å, c=20.2499(11) Å, β=103.2893(18)°, Z=4), and 2 crystallizes in the monoclinic system of the P21 space group (a=9.761(2) Å, b=19.573(5) Å, c=10.502(4) Å, β=109.247(12)°, Z=2). These two crystals consist of one-dimensional linear chains, in which [GdIII(DMA)n]3+ and [WV(CN)8]3− ions are linked in an alternating fashion. The difference between these two compounds, that is, 1 contains eight-coordinate GdIII whereas 2 contains seven-coordinate GdIII, is due to the temperature during preparation. Magnetic data showed that the magnetic interaction between GdIII (S=7⁄2) and WV (S=1⁄2) is antiferromagnetic coupling of −0.28(1) cm−1 for 1 and −0.42(1) cm−1 for 2.
Spin-Crossover Behavior of Isomorphous Bi- and Mononuclear Iron(III) Complexes
Authors: Imatomi Shinya , Sato Tetsuya , Hamamatsu Takefumi , Kitashima Ryoko , Matsumoto Naohide
Published: December 2007

Isomorphous bi- and mononuclear iron(III) complexes, [FeIII2L2(bimb)](BPh4)2 (1) and [FeIIIL(meim)]BPh4 (2), where H2L = bis(3-methoxysalicylideneaminopropyl)amine, bimb = 1,4-bisimidazolylbutane, meim = N-methylimidazole, and BPh4− = tetraphenylborate, respectively, were synthsized. Binuclear complex 1 showed a two-step spin-crossover (SCO) behavior at T1⁄2=60 and 90 K, whereas mononuclear complex 2 showed a one-step SCO behavior at T1⁄2=215 K. The different SCO behavior can be ascribed to the quasi-one-dimensional structure constructed by π–π stacking and the binuclear structure.
Nucleophilic Substitution Accompanying Carbon–Carbon Bond Cleavage Assisted by a Nitro Group
Authors: Nakaike Yumi , Taba Noriko , Itoh Shinobu , Tobe Yoshito , Nishiwaki Nagatoshi , Ariga Masahiro
Published: December 2007

A 2-nitrated 3-oxoester reacted with amines or alcohols to afford unsymmetrical malonic acid derivatives as a result of nucleophilic substitution accompanying C–C bond cleavage. The 2-nitrated 3-oxoester easily formed ammonium salts with amines. When the amine is liberated from the salt under equilibrium, nucleophilic amine and electrophilic keto ester locate close to each other. This intimate pair effect causes a pseudo intramolecular reaction to occur, giving rise to effective substitution under mild conditions.