bluuebunny/crossref_metadata_2025 huggingface dataset:
How Do Hawkmoths Learn Multimodal Stimuli? A Comparison of Three Models
Authors: Balkenius Anna , Kelber Almut , Balkenius Christian
Published: November 2008

The moth Macroglossum stellatarum can learn the color and sometimes the odor of a rewarding food source. We present data from 20 different experiments with different combinations of blue and yellow artificial flowers and the two odors, honeysuckle and lavender. The experiments show that learning about the odors depends on the color used. By training on different color—odor combinations and testing on others, it becomes possible to investigate the exact relation between the two modalities during learning. Three computational models were tested in the same experimental situations as the real moths and their predictions were compared with the experimental data. The average error over all experiments as well as the largest deviation from the experimental data were calculated. Neither the Rescorla—Wagner model nor a learning model with independent learning for each stimulus component were able to explain the experimental data. We present the new hawkmoth learning model, which assumes that the moth learns a template for the sensory attributes of the rewarding stimulus. This model produces behavior that closely matches that of the real moth in all 20 experiments.
Evaluating the Benefit of Hearing Aids in Solving the Cocktail Party Problem
Authors: Marrone Nicole , Mason Christine R. , Kidd Gerald
Published: November 2008

The benefit of wearing hearing aids in multitalker, reverberant listening environments was evaluated in a study of speech-on-speech masking with two groups of listeners with hearing loss (younger/older). Listeners selectively attended a known spatial location in two room conditions (low/high reverberation) and identified target speech in the presence of two competing talkers that were either colocated or symmetrically spatially separated from the target. The amount of spatial release from masking (SRM) with bilateral aids was similar to that when listening unaided at or near an equivalent sensation level and was negatively correlated with the amount of hearing loss. When using a single aid, SRM was reduced and was related to the level of the stimulus in the unaided ear. Increased reverberation also reduced SRM in all listening conditions. Results suggest a complex interaction between hearing loss, hearing aid use, reverberation, and performance in auditory selective attention tasks.
The Case of Top Beginnings and the Missing Child Outcomes
Authors: Walker Gary , Kubisch Anne C. , Bruner Charles , Sridharan Sanjeev , Philliber Susan , Shaw Greg , Dichter Harriet
Published: November 2008

The Case of Top Beginnings and the Missing Child Outcomes is a fictionalized case study of a set of evaluation challenges faced in evaluating comprehensive initiatives that are seeking to build systems. In this case, the issue is a multistate foundation-funded early learning system building initiative that has to date primarily employed a case study approach that has provided a formative assessment of progress in building systems. Funders, practitioners, and evaluators all have perspectives on what is needed next to inform future work. In particular, funders want to see evidence of progress and signs that there are impacts on children's development and readiness for school. The case poses fundamental questions in evaluating such complex initiatives that involve public will building and mobilization as well as implementation concerns. The case poses specific issues that need to be answered in moving to a next stage of evaluation.
Commentary on System Building Evaluation Case
Authors: Dichter Harriet
Published: November 2008

In April 2007, more than 50 practitioners, advocates, funders, and evaluators met for 2 days in Pittsburgh, Pennsylvania, to discuss the issues that arise in evaluating systems change or systems-building initiatives and to suggest approaches to resolving those issues. The symposium was designed to be as realistic and practical as possible by focusing discussion and problem solving on a case study of a hypothetical systems-building initiative aimed at improving early childhood outcomes.
Role Sharing Between Evaluators and Stakeholders in Practice
Authors: Cartland Jenifer , Ruch-Ross Holly S. , Mason Maryann , Donohue William
Published: November 2008

In the past three decades, program evaluation has sought to more fully engage stakeholders in the evaluative process. But little information has been gathered from stakeholders about how they share in evaluation tasks and whether role sharing leads to confusion or tensions between the evaluator and the stakeholders. This article reports findings from surveys and interviews with 20 evaluator—project director (lead stakeholder) pairs to explore how they share each other's roles in practice. In this study, sharing roles between evaluators and project directors generally was the norm among study participants but varied by the orientation of the evaluator (academic, program, or client). For some, there was tension and confusion in the role sharing of evaluators and stakeholders, but it was typically resolved early on in the cases where evaluators bring strong communication skills to the project. Where these skills were not present, the tensions did not resolve consistently.
The Creative Dimension of Lay Thinking in the Case of the Representation of Democracy for Greek Youth
Authors: Magioglou Thalia
Published: November 2008

This article intends to make a contribution to the study of lay thinking on democracy and proposes a theoretical framework based on the notion of the `argumentative pole' that I have developed in my Ph.D. dissertation (Magioglou, 2005) and will be further presented in a series of articles. It focuses on the dialogical and creative dimension of lay thinking, based in a question—answer style. Argumentative poles are a number of open questions, such as `what is good?', or what is democracy?', `who should act?' and `how?', that attract different and, at times, opposing answers. The answers present a dynamic tension between an organized and an ambivalent dimension. In this article, the presentation is focused on the contradictory and ambivalent dimension of lay thinking and draws, from a theoretical point of view, on perspectives in social and cultural psychology (Bruner, 1986; Marková, 2003; Moscovici, 1976; Valsiner & Van der Veer, 2000) that attend to language and social and cultural context. This contradictory element is related to the creative character of lay thinking as a form of social thinking: bringing together ideas that do not match according to logic or ideology, which allows new combinations and new representations of democracy to appear. I present data from the narrative analysis because it led to the notion of the `argumentative pole'. The logic of the presentation is theoretical and does not follow a linear demonstrative style. It is typical of qualitative research (Flick, 2002), where the results of the data analysis inspire a `grounded' theory that fits the research questions (Strauss, 1987).
Book Review Reply: On Subjective Culture: In Response to Carlos Cornejo
Authors: Boesch Ernst E.
Published: November 2008

Carlos Cornejo's book review on my Von Kunst bis Terror led me to the need to chart out a number of central issues in contemporary psychology that cultural psychology is in a position to resolve. Human subjectivity in all of its richness remains the core of investigation for all psychology, and cultural psychology has a central role to play in innovating psychology's research practices.
The strategic management of data quality in healthcare
Authors: Kerr Karolyn A. , Norris Tony , Stockdale Rosemary
Published: November 2008

This research extends and tests principles to establish good practice and overcome practical barriers in the strategic management of data quality. The research explores the issues that define and control data quality in national health data collections and the mechanisms and frameworks that can be developed to achieve and sustain good data quality. The aim is to make the strategic management of data quality, and the prevention of persistent errors, everyday, `institutionalized' activities. Using action research methodology and a combination of interpretive and positivist data collection and analysis methods, this research provides the health informatics community with an understanding of the issues related to developing and implementing programmes to improve data quality. Healthcare is a complex system that is highly political and culturally diverse, and applied health informatics research is essential to improve outcomes and performance.
Symbolic valorization in the culture of entertainment
Authors: Stromberg Peter
Published: November 2008

Durkheim argued that a society's central ideals are valorized through a process of emotional transfer that occurs as the excitement of intensive interaction comes to be associated with key symbols. In this article, I argue that a very similar process may occur in contemporary society as people interact with, and become deeply engaged in, the practices of entertainment and consumption. The argument is based upon a single example, routines of early phase legal drug consumption among college students. Legal drug use, like many forms of entertainment and discretionary consumption in contemporary American society, can in some cases be understood as a form of play. Often participants become caught up in their play, so preoccupied with the fictional world of the play that the cognitive and emotional salience of the day-to-day world begins to fade. Here I argue that for some beginning users of alcohol and tobacco, becoming caught up in this way enhances users' convictions about the capacity of the drug to produce strong transformative experiences and thereby valorizes the cultural conception of the drug as a substance that can override the ability of the person to direct his or her own action. I conclude by suggesting that becoming caught up in the fictions of play is a practice that may have relevance for understanding the effects of a broad range of activities that we classify as entertainment and consumption.
Journalism, education and the formation of 'public subjects'
Authors: Nolan David
Published: November 2008

In debates surrounding the role of universities in teaching journalism, a range of critical voices have stressed the importance of moving beyond the limiting frame of an assumed 'industry—academic dichotomy', while some also point to the structural forces that underpin the persistence of this frame. A consideration of such factors suggests that, while this critical move may be laudable, enacting such a shift in practice is likely to require more than simply good intentions or critical moralism. To this end, this article argues for an approach that considers how both educational and media institutions may be defined as key sites in the production of both journalists and audiences as 'public subjects'. Such a framework, it is argued, supports a more critical analysis of the role played by industry, practitioners and universities as active stakeholders in formations of journalistic professionalism, and the manner each are being impacted by trends toward 'professionalization'.
Doubly doped tin oxide films from cost effective spray technique using perfume atomiser
Authors: Ravichandran K. , Muruganantham G. , Saravanakumar K. , Karnan S. , Kannan B. , Chandramohan R. , Sakthivel B.
Published: November 2008

An inexpensive and simplified spray technique using perfume atomiser is employed for the fabrication of doubly doped antimony+fluorine tin oxide films from aqueous solutions of SnCl2 precursor having different molar concentrations. The preferred orientation is along the (110) plane. The degree of preferred orientation, texture coefficient and crystallinity of the films were found to increase with the increase in precursor concentration. The SEM images show that the films are homogeneous and uniform. The minimum sheet resistance obtained is 4·98 Ω/sq for concentration 0·8M. This may be the least value obtained for fluorine or antimony doped tin oxide film prepared from aqueous solution of SnCl2 precursor using spray pyrolysis technique. Wide optical band gap (3·51 eV), good visible transmittance (81%), considerable figure of merit (4·6×10−3 Ω−1) and high infrared reflectivity (77–95%) make these doubly doped films desirable candidates for low cost solar cell materials.
Stable, Intelligible Ultrasonic Strain Imaging
Authors: Gee Andrew , Lindop Joel , Treece Graham , Prager Richard , Freeman Susan
Published: November 2008

Background: Freehand quasistatic strain imaging can reveal qualitative information about tissue stiffness with good spatial accuracy. Clinical trials, however, repeatedly cite instability and variable signal-to-noise ratio as significant drawbacks.

Methods: This study investigates three post-processing strategies for quasistatic strain imaging. Normalization divides the strain by an estimate of the stress field, the intention being to reduce sensitivity to variable applied stress. Persistence aims to improve the signal-to-noise ratio by time-averaging multiple frames. The persistence scheme presented in this article operates at the pixel level, weighting each frame's contribution by an estimate of the strain precision. Precision-based display presents the clinician with an image in which regions of indeterminate strain are obscured behind a colour wash. This is achieved using estimates of strain precision that are faithfully propagated through the various stages of signal processing.

Results and discussion: The post-processing strategy is evaluated qualitatively on scans of a breast biopsy phantom and in vivo head and neck examinations. Strain images processed in this manner are observed to benefit from improved stability and signal-to-noise ratio. There are, however, limitations. In unusual though conceivable circumstances, the normalization procedure might suppress genuine stiffness variations evident in the unprocessed strain images. In different circumstances, the raw strain images might fail to capture significant stiffness variations, a situation that no amount of post-processing can improve.

Conclusion: The clinical utility of freehand quasistatic strain imaging can be improved by normalization, precision-weighted pixel-level persistence and precision-based display. The resulting images are stable and generally exhibit a better signal-to-noise ratio than any of the original, unprocessed strain images.
Profile of Women Seeking Fetal Gender at Ultrasound in a Nigerian Obstetric Population
Authors: Ekele Bissallah A. , Maaji Sadisu M. , Bello Shaibu O. , Morhason-Bello Imran O.
Published: November 2008

Objective: To determine the proportion of women that wanted to know fetal gender at ultrasound, characterize them and document reasons for wanting to know fetal gender.

Methodology: A cross-sectional study on consecutive pregnant women at 20 weeks or more gestation that presented for prenatal ultrasound at a private hospital in Nigeria from May to December 2005.

Results: Of the 1135 women, 167 (14·7%) sought to know the fetal gender. Significant independent factors included ethnic group, as women from the predominant Hausa–Fulani were less likely when compared to those of other ethnic groups (OR: 0·4, 95% CI: 0·2–0·7). Women with tertiary education were 6·6 times (OR: 6·6, 95% CI: 3·3–13·2) more likely. Women with a previous male baby were 30·6 times more likely (OR: 30·6, 95% CI: 13·6–68·5), while those with previous female baby were 54·3 times more likely (OR: 54·3; 95% CI: 23·4–125·8) to seek fetal gender. Main reasons for seeking fetal gender were preference for a particular fetal gender (57%); what wears to buy for the baby (24%) and curiosity (18%).

Conclusion: About 15% of the study group requested to know fetal gender and it was associated with ethnic group, maternal educational level and gender of the previous baby. The most common reason for wanting to know fetal gender was the desire for a particular gender.
CEACAM1 negatively regulates platelet-collagen interactions and thrombus growth in vitro and in vivo
Authors: Wong Cyndi , Liu Yong , Yip Jana , Chand Rochna , Wee Janet L. , Oates Lisa , Nieswandt Bernhard , Reheman Adili , Ni Heyu , Beauchemin Nicole , Jackson Denise E.
Published: November 2008

Carcinoembryonic antigen cell adhesion molecule-1 (CEACAM1) is a surface glycoprotein expressed on various blood cells, epithelial cells, and vascular cells. CEACAM1 possesses adhesive and signaling properties mediated by its intrinsic immunoreceptor tyrosine-based inhibitory motifs that recruit SHP-1 protein-tyrosine phosphatase. In this study, we demonstrate that CEACAM1 is expressed on the surface and in intracellular pools of platelets. In addition, CEACAM1 serves to negatively regulate signaling of platelets by collagen through the glycoprotein VI (GPVI)/Fc receptor (FcR)–γ-chain. ceacam1−/− platelets displayed enhanced type I collagen and GPVI-selective ligand, collagen-related peptide (CRP), CRP-mediated platelet aggregation, enhanced platelet adhesion on type I collagen, and elevated CRP-mediated alpha and dense granule secretion. Platelets derived from ceacam1−/− mice form larger thrombi when perfused over a collagen matrix under arterial flow compared with wild-type mice. Furthermore, using intravital microscopy to ferric chloride-injured mesenteric arterioles, we show that thrombi formed in vivo in ceacam1−/− mice were larger and were more stable than those in wild-type mice. GPVI depletion using monoclonal antibody JAQ1 treatment of ceacam1−/− mice showed a reversal in the more stable thrombus growth phenotype. ceacam1−/− mice were more susceptible to type I collagen–induced pulmonary thromboembolism than wild-type mice. Thus, CEACAM1 acts as a negative regulator of platelet-collagen interactions and of thrombus growth involving the collagen GPVI receptor in vitro and in vivo.
Concurrent up-regulation of BCL-XL and BCL2A1 induces approximately 1000-fold resistance to ABT-737 in chronic lymphocytic leukemia
Authors: Vogler Meike , Butterworth Michael , Majid Aneela , Walewska Renata J. , Sun Xiao-Ming , Dyer Martin J. S. , Cohen Gerald M.
Published: November 2008

ABT-737 and its orally active analog, ABT-263, are rationally designed inhibitors of BCL2 and BCL-XL. ABT-263 shows promising activity in early phase 1 clinical trials in B-cell malignancies, particularly chronic lymphocytic leukemia (CLL). In vitro, peripheral blood CLL cells are extremely sensitive to ABT-737 (EC50 ∼7 nM), with rapid induction of apoptosis in all 60 patients tested, independent of parameters associated with disease progression and chemotherapy resistance. In contrast to data from cell lines, ABT-737–induced apoptosis in CLL cells was largely MCL1-independent. Because CLL cells within lymph nodes are more resistant to apoptosis than those in peripheral blood, CLL cells were cultured on CD154-expressing fibroblasts in the presence of interleukin-4 (IL-4) to mimic the lymph node microenvironment. CLL cells thus cultured developed an approximately 1000-fold resistance to ABT-737 within 24 hours. Investigations of the underlying mechanism revealed that this resistance occurred upstream of mitochondrial perturbation and involved de novo synthesis of the antiapoptotic proteins BCL-XL and BCL2A1, which were responsible for resistance to low and high ABT-737 concentrations, respectively. Our data indicate that after therapy with ABT-737–related inhibitors, resistant CLL cells might develop in lymph nodes in vivo and that treatment strategies targeting multiple BCL2 antiapoptotic members simultaneously may have synergistic activity.
Colony-stimulating factor-1 (CSF-1) delivers a proatherogenic signal to human macrophages
Authors: Irvine Katharine M , Andrews Melanie R , Fernandez-Rojo Manuel A , Schroder Kate , Burns Christopher J , Su Stephen , Wilks Andrew F , Parton Robert G , Hume David A , Sweet Matthew J
Published: November 2008

M-CSF/CSF-1 supports the proliferation and differentiation of monocytes and macrophages. In mice, CSF-1 also promotes proinflammatory responses in vivo by regulating mature macrophage functions, but little is known about the acute effects of this growth factor on mature human macrophages. Here, we show that in contrast to its effects on mouse bone marrow-derived macrophages, CSF-1 did not induce expression of urokinase plasminogen activator mRNA, repress expression of apolipoprotein E mRNA, or prime LPS-induced TNF and IL-6 secretion in human monocyte-derived macrophages (HMDM) from several independent donors. Instead, we show by expression profiling that CSF-1 modulates the HMDM transcriptome to favor a proatherogenic environment. CSF-1 induced expression of the proatherogenic chemokines CXCL10/IFN-inducible protein 10, CCL2, and CCL7 but repressed expression of the antiatherogenic chemokine receptor CXCR4. CSF-1 also up-regulated genes encoding enzymes of the cholesterol biosynthetic pathway (HMGCR, MVD, IDI1, FDPS, SQLE, CYP51A1, EBP, NSDHL, DHCR7, and DHCR24), and expression of ABCG1, encoding a cholesterol efflux transporter, was repressed. Consistent with these effects, CSF-1 increased levels of free cholesterol in HMDM, and the selective CSF-1R kinase inhibitor GW2580 ablated this response. These data demonstrate that CSF-1 represents a further link between inflammation and cardiovascular disease and suggest two distinct mechanisms by which CSF-1, which is known to be present in atherosclerotic lesions, may contribute to plaque progression.
Sensitivity study of borehole-to-surface and crosswell electromagnetic measurements acquired with energized steel casing to water displacement in hydrocarbon-bearing layers
Authors: Pardo David , Torres-Verdín Carlos , Zhang (Ian) Zhiyi
Published: November 2008

We study the theoretical response of electromagnetically energized steel casing in the presence of subsurface variations of electrical resistivity. Casing is energized with a finite-size solenoid antenna located along the axis of the borehole. Measurements consist of the azimuthal component of the electric field acquired either on the surface or in a separate well in the same hydrocarbon field. We assume two-dimensional (2D) axisymmetric variations of subsurface electrical resistivity and casing excitation. Simulations of electromagnetic (EM) fields excited by energized steel casing are performed with a goal-oriented [Formula: see text]-adaptive finite-element method that automatically generates a sequence of optimal grids delivering exponential convergence rates in terms of the EM fields at the receiver antennas against CPU time. This advanced finite-element method enables accu-rate modeling of problems with high conductivity contrasts inlarge computational domains. Numerical simulations quantify the measurement sensitivity to variations of frequency, distance from casing to receivers, resistivity of the target oil-bearing layer, and pistonlike radial invasion of water within a target layer initially saturated with oil. When receivers are placed in a nearby well, numerical results indicate that measurements exhibit the largest sensitivity to the target (oil-saturated) layer when the transmitter or receiver antenna is located just above the target layer, and another antenna is located below the target layer. A frequency range from [Formula: see text] provides optimal results for the detection of oil-bearing layers and estimation of radial extent of water invasion. Large horizontal distances (up to [Formula: see text]) between transmitter and receivers and a background material with resistivity above [Formula: see text] also enhance the measurement sensitivity to radial variations of water invasion. This sensitivity can be as large as 15%–20% of the measured electric field.
Attribute-guided well-log interpolation applied to low-frequency impedance estimation
Authors: Hansen Thomas Mejer , Mosegaard Klaus , Pedersen-Tatalovic Radmila , Uldall Anette , Jacobsen Nils Lange
Published: November 2008

Several approaches exist to use trends in 3D seismic data, in the form of seismic attributes, to interpolate sparsely sampled well-log measurements between well locations. Kriging and neural networks are two such approaches. We have applied a method that finds a relation between seismic attributes (such as two-way times, interval velocities, reflector roughness) and rock properties (in this case, acoustic impedance) from information at well locations. The relation is designed for optimum prediction of acoustic impedances away from well sites, and this is accomplished through a combination of cross validation and the Tikhonov-regularized least-squares method. The method is fast, works well even for highly underdetermined problems, and has general applicability. We apply it to two case studies in which we estimate 3D cubes of low-frequency impedance, which is essential for producing good porosity models. We show that the method is superior to traditional least squares: Numerous blind tests show that estimated low-frequency impedance away from well locations can be determined with an accuracy very close to estimations obtained at well locations.
Impact of Small-Molecule Glucokinase Activator on Glucose Metabolism and β-Cell Mass
Authors: Nakamura Akinobu , Terauchi Yasuo , Ohyama Sumika , Kubota Junko , Shimazaki Hiroko , Nambu Tadahiro , Takamoto Iseki , Kubota Naoto , Eiki Junichi , Yoshioka Narihito , Kadowaki Takashi , Koike Takao
Published: November 2008

We investigated the effect of glucokinase activator (GKA) on glucose metabolism and β-cell mass. We analyzed four mouse groups: wild-type mice and β-cell-specific haploinsufficiency of glucokinase gene (Gck+/−) mice on a high-fat (HF) diet. Each genotype was also treated with GKA mixed in the HF diet. Rodent insulinoma cells and isolated islets were used to evaluate β-cell proliferation by GKA. After 20 wk on the above diets, there were no differences in body weight, lipid profiles, and liver triglyceride content among the four groups. Glucose tolerance was improved shortly after the GKA treatment in both genotypes of mice. β-Cell mass increased in wild-type mice compared with Gck+/− mice, but a further increase was not observed after the administration of GKA in both genotypes. Interestingly, GKA was able to up-regulate insulin receptor substrate-2 (Irs-2) expression in insulinoma cells and isolated islets. The administration of GKA increased 5-bromo-2-deoxyuridine (BrdU) incorporation in insulinoma cells, and 3 d administration of GKA markedly increased BrdU incorporation in mice treated with GKA in both genotypes, compared with those without GKA. In conclusion, GKA was able to chronically improve glucose metabolism for mice on the HF diet. Although chronic GKA administration failed to cause a further increase in β-cell mass in vivo, GKA was able to increase beta cell proliferation in vitro and with a 3-d administration in vivo. This apparent discrepancy can be explained by a chronic reduction in ambient blood glucose levels by GKA treatment.

Glucokinase activator is able to improve glucose metabolism and has an effect on β cell proliferation.
Minireview: The PGC-1 Coactivator Networks: Chromatin-Remodeling and Mitochondrial Energy Metabolism
Authors: Lin Jiandie D.
Published: November 2008

Transcriptional coactivators and corepressors are emerging as important regulators of energy metabolism and other biological processes. These factors exert their effects on the transcription of target genes through interaction with selective transcription factors and the recruitment of chromatin-remodeling complexes. Recent genetic and biochemical analyses of the peroxisomal proliferator-activated receptor-γ coactivator 1 networks provide novel mechanistic insights regarding their role in the control of mitochondrial oxidative metabolism. These coactivators integrate tissue metabolic functions in response to nutritional signals as well as circadian timing cues. In contrast to coactivators, transcriptional corepressors have been demonstrated to play an opposite role in the control of mitochondrial biogenesis and respiration. The balance of these coactivator and corepressor proteins and, more importantly, their access to specific transcriptional partners are predicted to dictate the epigenetic states of target genes as well as the metabolic phenotype of the cells. This review highlights the biological role and mechanistic basis of the peroxisomal proliferator-activated receptor-γ coactivator 1 networks in the regulation of chromatin-remodeling and mitochondrial oxidative metabolism.
Directing pathfinding along the dorsolateral path - the role of EDNRB2 and EphB2 in overcoming inhibition
Authors: Harris Melissa L. , Hall Ronelle , Erickson Carol A.
Published: November 2008

Neural crest cells that become pigment cells migrate along a dorsolateral route between the ectoderm and the somite, whereas most other neural crest cells are inhibited from entering this space. This pathway choice has been attributed to unique, cell-autonomous migratory properties acquired by neural crest cells when they become specified as melanoblasts. By shRNA knockdown and overexpression experiments, we investigated the roles of three transmembrane receptors in regulating dorsolateral pathfinding in the chick trunk. We show that Endothelin receptor B2 (EDNRB2) and EphB2 are both determinants in this process, and that, unlike in other species, c-KIT is not. We demonstrate that the overexpression of EDNRB2 can maintain normal dorsolateral migration of melanoblasts in the absence of EphB2, and vice versa, suggesting that changes in receptor expression levels regulate the invasion of this pathway. Furthermore, by heterotopic grafting, we show that neural crest cell populations that do not rely on the activation of these receptors can migrate dorsolaterally only if this path is free of inhibitory molecules. We conclude that the requirement for EDNRB2 and EphB2 expression by melanoblasts is to support their migration by helping them to overcome repulsive or non-permissive cues in the dorsolateral environment.
Foxg1 regulates retinal axon pathfinding by repressing an ipsilateral program in nasal retina and by causing optic chiasm cells to exert a net axonal growth-promoting activity
Authors: Tian Natasha M. , Pratt Thomas , Price David J.
Published: November 2008

Mammalian binocular vision relies on the divergence of retinal ganglion cell axons at the optic chiasm, with strictly controlled numbers projecting contralaterally and ipsilaterally. In mouse, contralateral projections arise from the entire retina, whereas ipsilateral projections arise from ventrotemporal retina. We investigate how development of these patterns of projection is regulated by the contralateral determinant Foxg1, a forkhead box transcription factor expressed in nasal retina and at the chiasm. In nasal retina, loss of Foxg1 causes increased numbers of ipsilateral projections and ectopic expression of the ipsilateral determinants Zic2, Ephb1 and Foxd1, indicating that nasal retina is competent to express an ipsilateral program that is normally suppressed by Foxg1. Using co-cultures that combine Foxg1-expressing with Foxg1-null retinal explants and chiasm cells, we provide functional evidence that Foxg1 promotes contralateral projections through actions in nasal retina, and that in chiasm cells, Foxg1 is required for the generation of a hitherto unrecognized activity supporting RGC axon growth.
TGFβ signals regulate axonal development through distinct Smad-independent mechanisms
Authors: Ng Julian
Published: November 2008

Proper nerve connections form when growing axons terminate at the correct postsynaptic target. Here I show that Transforming growth factor beta(TGFβ) signals regulate axon growth. In most contexts, TGFβ signals are tightly linked to Smad transcriptional activity. Although known to exist,how Smad-independent pathways mediate TGFβ responses in vivo is unclear. In Drosophila mushroom body (MB) neurons, loss of the TGFβreceptor Baboon (Babo) results in axon overextension. Conversely,misexpression of constitutively active Babo results in premature axon termination. Smad activity is not required for these phenotypes. This study shows that Babo signals require the Rho GTPases Rho1 and Rac, and LIM kinase1(LIMK1), which regulate the actin cytoskeleton. Contrary to the well-established receptor activation model, in which type 1 receptors act downstream of type 2 receptors, this study shows that the type 2 receptors Wishful thinking (Wit) and Punt act downstream of the Babo type 1 receptor. Wit and Punt regulate axon growth independently, and interchangeably, through LIMK1-dependent and -independent mechanisms. Thus, novel TGFβ receptor interactions control non-Smad signals and regulate multiple aspects of axonal development in vivo.
C2cd3 is required for cilia formation and Hedgehog signaling in mouse
Authors: Hoover Amber N. , Wynkoop Aaron , Zeng Huiqing , Jia Jinping , Niswander Lee A. , Liu Aimin
Published: November 2008

Cilia are essential for mammalian embryonic development as well as for the physiological activity of various adult organ systems. Despite the multiple crucial roles that cilia play, the mechanisms underlying ciliogenesis in mammals remain poorly understood. Taking a forward genetic approach, we have identified Hearty (Hty), a recessive lethal mouse mutant with multiple defects, including neural tube defects, abnormal dorsal-ventral patterning of the spinal cord, a defect in left-right axis determination and severe polydactyly (extra digits). By genetic mapping, sequence analysis of candidate genes and characterization of a second mutant allele, we identify Hty as C2cd3, a novel gene encoding a vertebrate-specific C2 domain-containing protein. Target gene expression and double-mutant analyses suggest that C2cd3 is an essential regulator of intracellular transduction of the Hedgehog signal. Furthering a link between Hedgehog signaling and cilia function, we find that cilia formation and proteolytic processing of Gli3 are disrupted in C2cd3 mutants. Finally, we observe C2cd3 protein at the basal body, consistent with its essential function in ciliogenesis. Interestingly, the human ortholog for this gene lies in proximity to the critical regions of Meckel-Gruber syndrome 2 (MKS2) and Joubert syndrome 2 (JBTS2), making it a potential candidate for these two human genetic disorders.
The mechanics of the gibbon foot and its potential for elastic energy storage during bipedalism
Authors: Vereecke Evie E. , Aerts Peter
Published: November 2008

The mechanics of the modern human foot and its specialization for habitual bipedalism are well understood. The windlass mechanism gives it the required stability for propulsion generation, and flattening of the arch and stretching of the plantar aponeurosis leads to energy saving. What is less well understood is how an essentially flat and mobile foot, as found in protohominins and extant apes, functions during bipedalism. This study evaluates the hypothesis that an energy-saving mechanism, by stretch and recoil of plantar connective tissues, is present in the mobile gibbon foot and provides a two-dimensional analysis of the internal joint mechanics of the foot during spontaneous bipedalism of gibbons using a four-link segment foot model. Available force and pressure data are combined with detailed foot kinematics, recorded with a high-speed camera at 250 Hz, to calculate the external joint moments at the metatarsophalangeal (MP), tarsometatarsal (TM)and talocrural (TC) joints. In addition, instantaneous joint powers are estimated to obtain insight into the propulsion-generating capacities of the internal foot joints. It is found that, next to a wide range of motion at the TC joint, substantial motion is observed at the TM and MP joint, underlining the importance of using a multi-segment foot model in primate gait analyses. More importantly, however, this study shows that although a compliant foot is less mechanically effective for push-off than a `rigid' arched foot, it can contribute to the generation of propulsion in bipedal locomotion viastretch and recoil of the plantarflexor tendons and plantar ligaments.
Low metabolic cost of locomotion in ornate box turtles,Terrapene ornata
Authors: Zani Peter A. , Kram Rodger
Published: November 2008

Evolution has produced a wide range of body plans, but for a given body mass, the energetic cost of transport (COT) of terrestrial animals falls in a relatively narrow range. Previous research indicates that the COT depends on the proficiency of minimizing mechanical work performed, efficiency of performing that work, and cost of generating force to support weight. Turtles are unique in that their protective shell and shoulder-girdle articulation may eliminate the need for the `muscular sling'. In addition, turtles have slower,more efficient muscles than other vertebrates. However, slow locomotion may raise the COT by confounding mechanical-energy conservation via the inverted-pendulum mechanism. Our goal was to determine the metabolic COT and efficiency of a terrestrial turtle species during locomotion. We studied 18 ornate box turtles, Terrapene ornata. Walking speed was extremely slow (0.07±0.005 m s–1). The average minimum COT was 8.0±0.70 J kg–1 m–1 attained at∼0.1 m s–1. Ornate box turtles consume only half the energy predicted by the allometric relationship for all terrestrial animals(15.9±0.35 J kg–1 m–1), and, thus,appear to be very economical walkers. When walking up a 24 deg. incline turtles moved significantly slower (0.04±0.004 m s–1),but performed the extra work required to walk uphill with very high efficiencies (>49%). It appears that the co-evolution of a protective shell, the associated shoulder morphology, and very slow, efficient muscles produce both economical level walking and efficient uphill walking.
The effect of humidity on the fracture properties of human fingernails
Authors: Farran Laura , Ennos A. Roland , Eichhorn Stephen J.
Published: November 2008

Fingernails are a characteristic anatomical feature of primates and their function is dictated by the environment in which they are utilised. The present study examined the mechanical properties of human fingernails as a function of relative humidity (RH) and the subsequent moisture content of the nail material. Nail clippings were stored at a range of RH values and then weighed in order to determine their moisture content. There was a non-linear relationship between the moisture content of nails and the RH of their local environment. The in vivo moisture content of nails, measured from 55%to 80% RH, was between 14% and 30%, similar to other keratinous materials such as claws, hooves and feathers. Cutting tests on the nail samples showed that the work of fracture was between 11 and 22 kJ m–2, rising to a peak at 55% RH and falling at higher and lower humidities. At all RH values there was anisotropy within the nail between the proximal and lateral directions, the work of fracture being greater proximally. This anisotropy was greatest at 55% RH, at which point the proximal work of fracture was double the lateral value. These results suggest that the mechanical behaviour of human fingernails is optimised at in vivo conditions; they resist tearing most strongly under these conditions and particularly resist tearing into the nail bed. At more extreme humidity levels the fracture properties of the nail deteriorate; they are brittle when fully dry and fracture and split when wet.
Characteristics of refrigeration systems — extension of the graphical—analytical method
Authors: Sulc V , Berge J B
Published: November 2008

Several different system balance methods and programmes have been developed and used for decades in the refrigeration industry to design refrigeration circuits and components. One of the oldest methods is the graphical—analytical method, developed and used long before computers and even calculators became standard engineering tools. The method is relatively easy and it helps to design and choose proper components. It can be successfully used today in the computer age for a better understanding of the refrigeration system behaviour, enabling the designer to see and evaluate major components, system characteristics, and system trends.

This article will introduce the graphical—analytical method for the simplest refrigeration systems and later extend it to more complex refrigeration systems.
Stabilized premixed combustion within atmospheric gas porous inert medium (PIM) burner
Authors: Bakry A I
Published: November 2008

In this study, a modified technique based on the quenching region concept is proposed to enhance the flame stability within porous inert media (PIM). The new technique eliminates disadvantageous features inherent with this category of PIM combustion, such as the high-pressure drop and the continuous degradation of the quenching region. To demonstrate the validity of the proposed technique, the premixed combustion of liquefied petroleum gas and air in the fuel-lean range in PIM burner under atmospheric pressure was examined experimentally. Improved relevant longitudinal temperature profiles and low levels of NO x and CO emissions could be obtained throughout the entire range of operating conditions with no traces of flashback formation. The results also revealed an extension of the fuel-lean burning limit beyond what was typically ex-perienced in free-flame combustion systems. Eventually, the stronger and more robust proposed configuration permits the utilization of PIM combustion technology to cover a new and wider spectrum of practical applications.
Hybrid sliding sector control for a wheeled mobile robot
Authors: Pan Y , Wei W , Furuta K
Published: November 2008

This paper proposes a hybrid control algorithm with sliding sectors for the control of a wheeled mobile robot (WMR), which is a non-holonomic system. The WMR control system with a set of available or pre-designed control laws is considered as a hybrid system with a set of subsystems. The WMR with one of control laws forms a non-linear subsystem of the hybrid system. The subsystems may be unstable but for each subsystem of the hybrid system, a stable subset called a sliding sector is designed such that a Lyapunov function candidate decreases inside the sliding sector. The hybrid control rule is used to stabilize the WMR control system by switching the hybrid system among its subsystems such that the system is always inside a sliding sector of some subsystem. The proposed hybrid sliding sector control algorithm has been successfully implemented to the real-time control of WMR with good control performance.
A new delay-dependent H∞ control criterion for a class of discrete-time systems with time-varying state delays and input delays
Authors: Wang Y , Zuo Y , Huang L , Wang Z
Published: November 2008

This paper deals with delay-dependent H∞ control for discrete-time systems with time-varying state delays and input delays. A new finite-sum inequality is first established to derive a delay-dependent condition, under which the resulting closed-loop system via a state feedback is asymptotically stable with a prescribed H∞ noise attenuation level. Moreover, a modified iterative algorithm according to the previously published algorithm of Ghaoui and Oustry ( IEEE Trans. Autom. Control, 1997, 42(8), 1171–1176) involving convex optimization is proposed to obtain a suboptimal H∞ controller. Two numerical examples are presented which show the effectiveness of the proposed method.
Model reference adaptive control system for laser surface treatments
Authors: Pérez J A , González M J , Naya M A
Published: November 2008

This paper presents a new real time model reference neural control system for laser surface treatments, which allows to improve significantly the uniformity and final quality of the process, reducing the rejection rate and increasing the productivity and efficiency of the treatment. The proposed neural controller essentially allows to assimilate the complex system dynamics to a simple first-order linear system, which can be easily controlled by a conventional proportional, integral and derivative controller, PID, providing exceptional results.
Analysis of the Design Parameters Related to a Fixed-Pitch Straight-Bladed Vertical Axis Wind Turbine
Authors: Islam Mazharul , Fartaj Amir , Carriveau Rupp
Published: November 2008

The fixed-pitch straight-bladed vertical axis wind turbine (SB-VAWT) is one of the simplest types of wind turbine. One of the main challenges of wide spread application of the smaller-capacity SB-VAWT is to design and develop it in a cost-effective manner. The overall cost of the SB-VAWT will mainly depend on judicious choice of multiple design parameters. An attempt has been made in this paper to identify and critically analyze the main design parameters related to smaller-capacity fixed-pitch SB-VAWT. It has been demonstrated in this paper that proper selections of these parameters are vital for a cost-effective smaller-capacity SB-VAWT which can be considered as a candidate for urban and off-grid rural applications.
Characteristics and Perspectives of Wind Energy in Morocco
Authors: Nfaoui H. , Essiarab H. , Sayigh A.
Published: November 2008

Morocco depends on 85% foreign sources of its energy supply. The oil invoice accounts for nearly 22.3% income from exports. In Morocco, the use of wind energy began before 1930, through the importation of windmills from USA by the French colony, to pump water for livestock and population in the country. An estimated 1000 of these units were in use in Morocco [1].

Following the rising price of oil after the first oil-price shock in the early 1970s, the days of cheap and plentiful petroleum were drawing to an end. Morocco began to promote and develop renewable energy mainly solar energy.

Wind energy is the most promising alternative energy resource in Morocco because of its good geographic location (3446 km of coast, Straits of Gibraltar, Rif and Atlas Mountain at 4167 metres and the Taza corridor) which permits Morocco to have available the largest wind potential in the North Africa. At 10 m, the annual mean wind speed can reach 11m/s in the Tetouan region and 8 m/s in the Dakhla site. The Moroccan wind potential is estimated at 21,000MW.

In the framework of diversification of national energy resources, various actions have been taken for the use of wind energy as a national energy resource. It is mainly about:

Since wind energy is economic on windy sites and the capital costs are continue to decline with the move to larger wind turbines [2,3], the Moroccan government has set a target of achieving 20% of its electricity supply from wind energy by 2020. It has started to pay attention to developing its indigenous wind energy resources and has encouraged wind technology transfer from other countries. On top of that, wind energy could have a significant and beneficial impact on the environment, particularly with regard to the greenhouse effect.

- Diversifying the actors, both public and private,

- Concluding consessional contracts between the National Office of Electricity (ONE) and private electricity producers using wind energy to satisfy theirs own needs,

- Increasing the autoproduction threshold to 50MW with the aim of installing 1000MW by modifying the laws governing the electricity production.