bluuebunny/crossref_metadata_2025 huggingface dataset:
Preflight Diffusion Experiments on Liquid Metals Under 1g Conditions for the FOTON‐M2 Mission
Authors: SUZUKI SHINSUKE , KRAATZ KURT‐HELMUT , FROHBERG GÜNTER , ROŞU RALCA , WENDL WOLFGANG , MÜLLER‐VOGT GERMAN
Published: November 2006

Abstract:  We measured diffusion of up to 5% Ag in liquid Pb, using the Foton shear cell (designed and used for the FOTON‐M2 mission). Since the density change of the alloy with composition has been reported to be very small but is not reliably known, we performed two arrangements of layering: (a) with PbAg on top and Pb below and (b) with Pb on top and PbAg below. The Berlin group did interdiffusion experiments from a “thick layer” of PbAg into “semi‐infinite” Pb and the Karlsruhe group did the typical “interdiffusion” experiments with a diffusion couple of PbAg versus Pb. The results of both groups were equivalent, showing much lower D values for arrangement (b) than for (a). The lower values were even definitely lower than reference microgravity values from MIR/MIM and could be fitted by D=ATn with n about 2.2. We discuss the stability/instability by density layering depending on the arrangement.
National and International Response to Occupational Hazards in the Healthcare Sector
Authors: FRONEBERG BRIGITTE
Published: November 2006

Abstract:  The health care sector is one of the largest, most rapidly expanding areas of employment and is increasingly in need of qualified staff especially in the area of nursing. The health care sector is complex and comprises a variety of largely different professions; occupational hazards and exposures differ accordingly. Rates of absenteeism, reported work‐related ill‐health, and early retirement or departure from professions are comparatively high, especially among the nursing staff. While classical health hazards are addressed by international and national regulations, underlying causes of ill‐health and departure from the profession, such as psychological stress, violence, pressing time schedules, and poor work organization are less well heeded. Practical guidance and quality information have become increasingly available from national and international Occupational Safety and Health (OSH) institutions and can be easily accessed through the Internet. They will undoubtedly benefit the profession, but difficulties not related to OSH will warrant political solutions. This presentation provides access to relevant international and European Union (EU) legislation and to valuable information resources for health care workers available from the Internet.
Gene Expression Alterations in Immune System Pathways following Exposure to Immunosuppressive Chemicals
Authors: PATTERSON RACHEL M. , GERMOLEC DORI R.
Published: November 2006

Abstract:  Exposure to environmental agents can affect a number of adverse immunological outcomes, including changes in the incidence of infectious disease. Diethylstilbestrol (DES), dexamethasone (DEX), cyclophosphamide, and 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD) are immunosuppressive chemicals that can induce similar pathophysiological end points in the thymus; however, the mechanism of toxicity is different for each compound. We examined differential gene expression in the spleen and thymus following chemical exposure and correlated these changes with alterations in functional immune end points and our knowledge of the known mechanisms of action. RNA from the spleen and thymus has been analyzed using Illumina Sentrix arrays and BeadStudio software. Preliminary data suggest that DES induced the greatest number of gene changes in the spleen, while DEX induced the most changes in the thymus. In both spleen and thymus, genomic analysis revealed gene expression changes that were common to multiple chemicals and that may be associated with xenobiotic‐induced immune system perturbations, including alterations in genes associated with apoptosis, antigen processing and presentation, and response to biotic stimulus. This was particularly evident in the thymus, where there were many similarities in the expression profiles, as well as gene alterations unique to a single compound. In contrast, expression profiles in spleen were more distinct. The category of genes most profoundly affected by all four chemicals was response to biotic stimulus: there were both clusters of genes modulated by multiple chemicals and genes altered by a single chemical. The distinct gene profiles may specifically relate to cellular targets and mechanism of action.
The Health Watch Case–Control Study of Leukemia and Benzene
Authors: GLASS DEBORAH C. , GRAY CHRISTOPHER N. , JOLLEY DAMIEN J. , GIBBONS CARL , SIM MALCOLM R.
Published: November 2006

Abstract:  A case–control study nested in the Health Watch cohort of petroleum industry workers, investigated whether the excess of lymphohematopoetic cancers, identified among male members of the Health Watch cohort, was associated with benzene exposure. Cases of non‐Hodgkin's lymphoma (n= 31), multiple myeloma (n= 15), and leukemia (n= 33) were identified between 1981 and 1999. Cases were age‐matched to five controls. Exposure was retrospectively estimated for each occupational history using an algorithm in a relational database. Benzene exposure measurements, supplied by Australian petroleum companies, were used to estimate exposure for specific tasks. The tasks carried out within the job, the products handled, and the technology used, were identified from interviews with contemporary colleagues. More than half of the subjects started work after 1965 and had an average exposure period of 20 years. Exposure was low, 85% of the cumulative exposure estimates were <10 ppm years. Matched analyses showed that non‐Hodgkin's lymphoma and multiple myeloma were not associated with benzene exposure. Leukemia risk, however, was significantly increased for the subjects with greater than 16 ppm years cumulative exposure, odds ratio (OR) 51.9 (5.6–477) or with greater than 0.8 ppm intensity of highest exposed job. Cumulative exposures were similar to those found in comparable studies. The inclusion of occasional high exposures, for example, as a result of spillages, reduced the ORs, when the exposure was treated as either a continuous or a categorical variable.
Our data demonstrate a strong association between leukemia and modest benzene exposure. The choice of cut‐point and reference group has a marked effect on the ORs, but does not change the overall conclusions.
Chemical Hazards in Health Care
Authors: McDIARMID MELISSA A.
Published: November 2006

Abstract:  It is counter‐intuitive that the healthcare industry, whose mission is the care of the sick, is itself a “high‐hazard” industry for the workers it employs. Possessing every hazard class, with chemical agents in the form of pharmaceuticals, sterilants, and germicidals in frequent use, this industry sector consistently demonstrates poor injury and illness statistics, among the highest in the United States, and in the European Union (EU), 34% higher than the average work‐related accident rate. In both the United States and the EU, about 10% of all workers are employed in the healthcare sector, and in developing countries as well, forecasts for the increasing need of healthcare workers (HCW) suggests a large population at potential risk of health harm. The explosion of technology growth in the healthcare sector, most obvious in pharmaceutical applications, has not been accompanied by a stepped up safety program in hospitals. Where there is hazard recognition, the remedies are often voluntary, and often poorly enforced. The wrong assumption that this industry would police itself, given its presumed knowledge base, has also been found wanting. The healthcare industry is also a significant waste generator threatening the natural environment with chemical and infectious waste and products of incineration. The ILO has recommended that occupational health goals for industrial nations focus on the hazards of new technology of which pharma and biopharma products are the leaders. This unchecked growth cannot continue without a parallel commitment to the health and safety of workers encountering these “high tech” hazards. Simple strategies to improve the present state include: (a) recognizing healthcare as a “high‐hazard” employment sector; (b) fortifying voluntary safety guidelines to the level of enforceable regulation; (c) “potent” inspections; (d) treating hazardous pharmaceuticals like the chemical toxicants they are; and (e) protecting HCWs at least as well as workers in other high‐hazard sectors.
Power‐Frequency Electric and Magnetic Fields in the Light of Draper et al. 2005
Authors: SWANSON JOHN , VINCENT TIM , KROLL MARY , DRAPER GERALD
Published: November 2006

Abstract:  Power‐frequency electric and magnetic fields are produced wherever electricity is used; exposure is ubiquitous. Epidemiologic studies find an association between children living in homes with the highest magnetic fields and childhood leukemia, but bias is a possible alternative to a causal explanation. A new study, Draper et al., looks at residence close to high‐voltage power lines, one source of exposure to such fields, and its design avoids any obvious bias. It finds elevated childhood leukemia rates, but extending too far from the power lines to be straightforwardly compatible with the existing literature. This leads to an examination of alternative explanations: magnetic fields, other physical factors, such as corona ions, the characteristics of the areas power lines pass through, bias, and chance. The conclusion is that there is currently no single preferred explanation, but that this is a serious body of science that needs further work until an explanation is found.
Health Effects of Hazardous Waste
Authors: DEARWENT STEVE M. , MUMTAZ M. MOIZ , GODFREY GAIL , SINKS THOMAS , FALK HENRY
Published: November 2006

Abstract:  Since 1995, the Agency for Toxic Substances and Disease Registry (ATSDR) has evaluated environmental contaminants and human health risks at nearly 3000 sites. Hazardous substances at these sites include newly emerging problems as well as historically identified threats. ATSDR classifies sites according to the degree of hazard they represent to the public. Less than 1% of the sites investigated are considered urgent public health hazards where chemical or physical hazards are at levels that could cause an immediate threat to life or health. Approximately 20% of sites have a potential for long‐term human exposures above acceptable risk levels. At almost 40% of sites, hazardous substances do not represent a public health hazard. Completed exposure pathways for contaminants in air, water, and soil have been reported at approximately 30% of evaluated sites. The most common contaminants of concern at these sites include heavy metals, volatile organic compounds, and polychlorinated biphenyls. This article reviews ATSDR's ongoing work by examining the historic hazard of lead, the contemporary hazard of asbestos, and the emerging issue of perchlorate contamination.
Emergency Medicine Practitioner Knowledge and Use of Decision Rules for the Evaluation of Patients with Suspected Pulmonary Embolism: Variations by Practice Setting and Training Level
Authors: Runyon Michael S. , Richman Peter B. , Kline Jeffrey A.
Published: November 2006

Background

Several clinical decision rules (CDRs) have been validated for pretest probability assessment of pulmonary embolism (PE), but the authors are unaware of any data quantifying and characterizing their use in emergency departments.

Objectives

To characterize clinicians' knowledge of and attitudes toward two commonly used CDRs for PE.

Methods

By using a modified Delphi approach, the authors developed a two‐page paper survey including 15 multiple‐choice questions. The questions were designed to determine the respondents' familiarity, frequency of use, and comprehension of the Canadian and Charlotte rules. The survey also queried the frequency of use of unstructured (gestalt) pretest probability assessment and reasons why physicians choose not to use decision rules. The surveys were sent to physicians, physician assistants, and medical students at 32 academic and community hospitals in the United States and the United Kingdom.

Results

Respondents included 555 clinicians; 443 (80%) work in academic practice, and 112 (20%) are community based. Significantly more academic practitioners (73%) than community practitioners (49%) indicated familiarity with at least one of the two decision rules. Among all respondents familiar with a rule, 50% reported using it in more than half of applicable cases. A significant number of these respondents could not correctly identify a key component of the rule (23% for the Charlotte rule and 43% for the Canadian rule). Fifty‐seven percent of all respondents indicated use of gestalt rather than a decision rule in more than half of cases.

Conclusions

Academic clinicians were more likely to report familiarity with either of these two specific decision rules. Only one half of all clinicians reporting familiarity with the rules use them in more than 50% of applicable cases. Spontaneous recall of the specific elements of the rules was low to moderate. Future work should consider clinical gestalt in the evaluation of patients with possible PE.
Factors Associated with Hospital Admission among Emergency Department Patients with Chronic Obstructive Pulmonary Disease Exacerbation
Authors: Tsai Chu‐Lin , Clark Sunday , Cydulka Rita K. , Rowe Brian H. , Camargo Carlos A.
Published: November 2006

Objectives

To determine the patient factors associated with hospital admission among adults who present to the emergency department (ED) with acute exacerbations of chronic obstructive pulmonary disease (COPD) and to determine whether admissions were concordant with recommendations in the Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines.

Methods

The authors performed a prospective multicenter cohort study involving 29 EDs in the United States and Canada. By using a standard protocol, consecutive ED patients with COPD exacerbation were interviewed, and their charts were reviewed. Predictors of admission were determined by multivariate logistic regression.

Results

Of 384 patients, 233 (61%; 95% confidence interval = 56% to 66%) were admitted. Multivariate analysis showed that a higher likelihood of admission was associated with older age, female gender, more pack‐years of smoking, recent use of inhaled corticosteroid, self‐reported activity limitation in the past 24 hours, higher respiratory rate at ED presentation, and a concomitant diagnosis of pneumonia. Patients who reported the ED as their usual site for problem COPD care, or who had mixed COPD and asthma, were less likely to be admitted. The authors confirmed five of the seven testable indications for hospital admission in the GOLD guidelines.

Conclusions

Several patient factors were independently associated with hospital admission among ED patients with COPD exacerbations. Overall, concordance with admission recommendations in the GOLD guidelines was high. The authors also identified a few novel predictors of admission (female gender, ED as the usual site for problem COPD care, mixed diagnosis of COPD and asthma, recent use of inhaled corticosteroid) that require replication in future studies.
Suppression of Androgen Receptor Transactivation and Prostate Cancer Cell Growth by Heterogeneous Nuclear Ribonucleoprotein A1 via Interaction with Androgen Receptor Coregulator ARA54
Authors: Yang Zhiming , Chang Yu-Jia , Miyamoto Hiroshi , Yeh Shuyuan , Yao Jorge L. , di Sant’Agnese P. Anthony , Tsai Meng-Yin , Chang Chawnshang
Published: November 2006

The androgen receptor (AR) requires coregulators for its optimal transactivation. Whether AR coregulators also need interacting proteins to modulate their function remains unclear. Here we describe heterogeneous nuclear ribonucleoprotein (hnRNP) A1 as an associated negative modulator for the AR coregulator ARA54. hnRNP A1 selectively suppressed ARA54-enhanced wild-type and mutant AR transactivation via interruption of AR-ARA54 interaction and ARA54 homodimerization. Stable transfection of hnRNP A1 in the LNCaP cells suppressed AR-mediated cell growth and the expression of prostate-specific antigen, and this suppressive effect was abolished by the addition of ARA54-small interfering RNA. Small interfering RNA knockdown of endogenous hnRNP A1 enhanced cell growth and prostate-specific antigen expression in LNCaP cells. These results not only suggest that the loss of hnRNP A1 expression might activate the ARA54-enhanced cell growth and contribute to the prostate cancer progression, but also demonstrate the dual functional roles for ARA54 as an AR coregulator directly and as a mediator for the suppressive effect of hnRNP A1 indirectly. The novel finding that a protein can modulate AR function without direct interaction with AR might provide a new therapeutic approach to battle prostate cancer by targeting AR indirectly with fewer side effects.
Osteopontin Protects the Islets and β-Cells from Interleukin-1 β-Mediated Cytotoxicity through Negative Feedback Regulation of Nitric Oxide
Authors: Arafat Hwyda A. , Katakam Anand K. , Chipitsyna Galina , Gong Qiaoke , Vancha Ajith R. , Gabbeta Jagadeesh , Dafoe Donald C.
Published: November 2006

Osteopontin (OPN), a phosphorylated glycoprotein that binds to an integrin-binding motif, has been shown to regulate nitric oxide (NO) production via inhibition of induced NO synthase (iNOS) synthesis. In the transplanted islets, iNOS and toxic amounts of NO are produced as a result of islets infiltration with inflammatory cells and production of proinflammatory cytokines. Here, we demonstrate that addition of OPN before IL-1β in freshly isolated rat islets improved their glucose stimulated insulin secretion dose-dependently and inhibited IL-1β-induced NO production in an arginine-glycine-aspartate-dependent manner. Transient transfection of OPN gene in RINm5F β-cells fully prevented the toxic effect of IL-1β at concentrations that reduced the viability by 50% over 3 d. OPN prevention of IL-1β-induced toxicity was accompanied by inhibited transcription of iNOS by 80%, resulting in 50% decreased formation of the toxic NO. In OPN-transfected cells, the IL-1β-induced nuclear factor-κB activity was significantly reduced. Islets exposed to IL-1β revealed a naturally occurring early up-regulated OPN transcription. OPN promoter activity was increased in the presence of IL-1β, IL-1β-induced NO, and an inducer of NO synthesis. These data suggest the presence of a cross talk between the IL-1β and OPN pathways and a unique trans-regulatory mechanism in which IL-1β-induced NO synthesis feedback regulates itself through up-regulation of OPN gene transcription. Our data also suggest that influencing OPN expression represents an approach for affecting cytokine-induced signal transduction to prevent or reduce activation of the cascade of downstream devastating effects after islet transplantation.
Analysis of the Gene Regulatory Program Induced by the Homeobox Transcription Factor Distal-less 3 in Mouse Placenta
Authors: Han Li , Dias Figueiredo Monica , Berghorn Kathie A. , Iwata Terri N. , Clark-Campbell Patricia A. , Welsh Ian C. , Wang Wei , O’Brien Timothy P. , Lin David M. , Roberson Mark S.
Published: November 2006

Dlx3, a homeodomain transcription factor, is essential for placental development in the mouse. The Dlx3−/− mouse embryo dies at embryonic d 9.5–10 putatively due to placental failure. To develop a more comprehensive understanding of the gene profile regulated by Dlx3, microarray analysis was used to determine differences in gene expression within the placenta of Dlx3+/+ and Dlx3−/− mice. Array analysis revealed differential expression of 401 genes, 33 genes in which signal to log ratio values of null/wild-type were lower than −0.5 or higher than 0.5. To corroborate these findings, quantitative real-time PCR was used to confirm differential expression for 11 genes, nine of which displayed reduced expression and two with enhanced expression in the Dlx3−/− mouse. Loss of Dlx3 resulted in a marked reduction (>60%) in mRNA expression of placental growth factor (Pgf), a member of the vascular endothelial growth factor family. Consistent with these results, Pgf secretion from placental explants tended to be reduced in the Dlx3−/− mice, compared with wild type. To investigate mechanisms of Dlx3 regulation of Pgf gene transcription, we cloned 5.2 kb of the Pgf 5′ flanking sequence for use in reporter gene assays. Expression of the Pgf promoter luciferase reporter containing at least three Dlx3 binding sites was increased markedly by overexpression of Dlx3 supporting the conclusion that Dlx3 may have a direct effect on Pgf promoter activity. These studies provide a novel view of the transcriptome regulated by Dlx3 in mouse placenta. Dlx3 is specifically required for full expression and secretion of Pgf in vivo. Moreover, in vitro studies support the conclusion that Dlx3 is sufficient to directly modulate expression of the Pgf gene promoter in placental cells.
Morphology and action of the hind leg joints controlling jumping in froghopper insects
Authors: Burrows Malcolm
Published: November 2006

The morphology and movements of key joints of the hind legs that generate the rapid jumping of froghoppers were analysed. The movements of an individual hind leg during a jump occur in three phases. First, the trochanter is slowly levated about the coxa so that the femur moves anteriorly and engages with a lateral protrusion on the coxa. Second, both hind legs are held in this fully levated (cocked) position without moving for a few seconds. Third, both hind legs depress and extend completely in less than 1 ms. The critical,power-generating movement underlying a jump is the rapid and simultaneous depression of the trochantera about the coxae.

The lever arm of the hind trochanteral depressor muscle is smallest at the cocked position, but does not appear to go over the centre of the pivot. It then increases to a maximum after some 80° of depression movement. By contrast, the lever arm of the trochanteral levator tendon is similar over the range of joint movements and is exceeded by that of the depressor only after 40° of depression. Three prominent arrays of hairs on the trochantin, coxa and trochanter are appropriately positioned to act as proprioceptors signalling key movements in jumping.

In the fully levated position, a protrusion on the dorsal, proximal surface of a hind femur engages with a protrusion from the ventral and lateral part of a coxa. These structures are not present on the front and middle legs. Both protrusions are covered with a dense array of small projections (microtrichia)that both increase the surface area and may interlock with each other. To depress rapidly in a jump these protrusions must disengage. If the hind leg of a dead froghopper is forcibly levated, it will lock in its cocked position,from which it can depress rapidly by movement of the coxo-trochanteral joint and disengagement of the femoral and coxal protrusions. A prominent click sound occurs at the start of a jump that results either from the initial movements of the coxo-trochanteral joint, or from the disengagement of the microtrichia on the coxa and femur. Larval Philaenus, which do not jump, lack a femoral protrusion and have no microtrichia in equivalent positions on either the coxa or femur.
Biomimetic evolutionary analysis: testing the adaptive value of vertebrate tail stiffness in autonomous swimming robots
Authors: Long J. H. , Koob T. J. , Irving K. , Combie K. , Engel V. , Livingston N. , Lammert A. , Schumacher J.
Published: November 2006

For early vertebrates, a long-standing hypothesis is that vertebrae evolved as a locomotor adaptation, stiffening the body axis and enhancing swimming performance. While supported by biomechanical data, this hypothesis has not been tested using an evolutionary approach. We did so by extending biomimetic evolutionary analysis (BEA), which builds physical simulations of extinct systems, to include use of autonomous robots as proxies of early vertebrates competing in a forage navigation task. Modeled after free-swimming larvae of sea squirts (Chordata, Urochordata), three robotic tadpoles (`Tadros'), each with a propulsive tail bearing a biomimetic notochord of variable spring stiffness, k (N m-1), searched for, oriented to, and orbited in two dimensions around a light source. Within each of ten generations, we selected for increased swimming speed, U (m s-1) and decreased time to the light source, t (s),average distance from the source, R (m) and wobble maneuvering, W (rad s-2). In software simulation, we coded two quantitative trait loci (QTL) that determine k: bending modulus, E (Nm-2) and length, L (m). Both QTL were mutated during replication, independently assorted during meiosis and, as haploid gametes, entered into the gene pool in proportion to parental fitness. After random mating created three new diploid genotypes, we fabricated three new offspring tails. In the presence of both selection and chance events(mutation, genetic drift), the phenotypic means of this small population evolved. The classic hypothesis was supported in that k was positively correlated (r2=0.40) with navigational prowess, NP, the dimensionless ratio of U to the product of R, t and W. However, the plausible adaptive scenario, even in this simplified system, is more complex, since the remaining variance in NP was correlated with the residuals of R and U taken with respect to k, suggesting that changes in k alone are insufficient to explain the evolution of NP.
Magnetic compass in the cornea: local anaesthesia impairs orientation in a mammal
Authors: Wegner Regina E. , Begall Sabine , Burda Hynek
Published: November 2006

The mechanism of signal transduction during magnetic compass orientation is rarely evident in vertebrates and is as yet unknown in mammals. This transmission has been associated with magnetite-based receptors innervated by the ophthalmic nerve or with the involvement of the eye, particularly the retina. We provide the first behavioural support for the cornea carrying the respective primary sensors in mole-rats (Fukomys anselli) by showing that local anaesthesia disrupts their normal directional magnetic orientation. During corneal anaesthesia in normal geomagnetic conditions, mole-rats did not maintain their preferred nesting direction, but displayed a random orientation pattern. A second experiment showed that the ability of the mole-rat to discriminate between light and dark was not impeded by the same anaesthetic treatment, suggesting no retinal involvement in mole-rat magnetic orientation. Our study restricts the peripheral primary sensors in mole-rats to the ophthalmic region, probably the cornea and indicates magnetite as the responsible signal mediator.
Structure and sexual dimorphism of the electrocommunication signals of the weakly electric fish,Adontosternarchus devenanzii
Authors: Zhou Muchu , Smith G. Troy
Published: November 2006

Electrocommunication signals of electric fish vary across species, sexes and individuals. The diversity of these signals and the relative simplicity of the neural circuits controlling them make them a model well-suited for studying the mechanisms, evolution and sexual differentiation of behavior. In most wave-type gymnotiform knifefishes, electric organ discharge (EOD)frequency and EOD modulations known as chirps are sexually dimorphic. In the most speciose gymnotiform family, the Apteronotidae, EOD frequency is higher in males than females in some species, but lower in males than females in others. Sex differences in EOD frequency and chirping, however, have been examined in only three apteronotid species in a single genus, Apteronotus. To understand the diversity of electrocommunication signals, we characterized these behaviors in another genus, Adontosternarchus. Electrocommunication signals of Adontosternarchus devenanzii differed from those of Apteronotus in several ways. Unlike in Apteronotus, EOD frequency was not sexually dimorphic in A. devenanzii. Furthermore,although A. devenanzii chirped in response to playbacks simulating conspecific EODs, the number of chirps did not vary with different stimulus frequencies. A. devenanzii chirps also differed in structure from Apteronotus chirps. Whereas Apteronotus species produce functionally distinct chirp types differing in frequency modulation (FM), A. devenanzii produced only high-frequency chirps that had either single or multiple frequency peaks. Males produced more multi-peaked chirps than females. Thus, the temporal structure of chirps, rather than the amount of FM, delineated chirp types in A. devenanzii. Our results demonstrate that the structure, function and sexual dimorphism of electrocommunication signals are evolutionary labile in apteronotids and may be useful for understanding the diversity of sexually dimorphic behavior.
Lipid remodeling in wild and selectively bred hard clams at low temperatures in relation to genetic and physiological parameters
Authors: Pernet Fabrice , Tremblay Réjean , Gionet Chantal , Landry Thomas
Published: November 2006

A temperature decrease usually induces an ordering effect in membrane phospholipids, which can lead to membrane dysfunction. Poikilotherms inhabiting eurythermal environments typically counteract this temperature effect by remodeling membrane lipids as stipulated in the homeoviscous adaptation theory (HVA). Hard clams, Mercenaria mercenaria, can suffer high overwintering mortalities in the Gulf of St Lawrence, Canada. The selectively bred M. mercenaria var. notata can have higher overwintering mortalities than the wild species, thus suggesting that the two varieties have different degrees of adaptation to low temperatures. The objective of this study was to investigate the changes in lipid composition of soft tissues in wild and selected hard clams in relation to their metabolic and genetic characteristics. Clams were placed at the northern limit of their distribution from August 2003 to May 2004; they were exposed to a gradual temperature decrease and then maintained at <0°C for 3.5 months. This study is the first to report a major remodeling of lipids in this species as predicted by HVA; this remodeling involved a sequential response of the phospholipid to sterol ratio as well as in levels of 22:6n-3 and non-methylene interrupted dienoic fatty acids. Hard clams showed an increase in 20:5n-3 as temperature decreased, but this was not maintained during overwintering, which suggests that 20:5n-3 may have been used for eicosanoid biosynthesis as a stress response to environmental conditions. Selectively bred hard clams were characterized by a higher metabolic demand and a deviation from Hardy-Weinberg equilibrium at several genetic loci due to a deficit in heterozygote frequency compared with wild clams, which is believed to impose additional stress and render these animals more vulnerable to overwintering mortality. Finally, an intriguing finding is that the lower metabolic requirements of wild animals coincide with a lower unsaturation index of their lipids, as predicted by Hulbert's theory of membranes as pacemakers of metabolism.
A comparison of visual and haltere-mediated feedback in the control of body saccades inDrosophila melanogaster
Authors: Bender John A. , Dickinson Michael H.
Published: November 2006

The flight trajectories of fruit flies consist of straight flight segments interspersed with rapid turns called body saccades. Although the saccades are stereotyped, it is not known whether their brief time course is due to a feed-forward (predetermined) motor program or due to feedback from sensory systems that are reflexively activated by the rapid rotation. Two sensory modalities, the visual system and the mechanosensory halteres, are likely sources of such feedback because they are sensitive to angular velocities within the range experienced during saccades. Utilizing a magnetic tether in which flies are fixed in space but free to rotate about their yaw axis, we systematically manipulated the feedback from the visual and haltere systems to test their role in determining the time course of body saccades. We found that altering visual feedback had no significant effect on the dynamics of saccades, whereas increasing and decreasing the amount of haltere-mediated feedback decreased and increased saccade amplitude, respectively. In other experiments, we altered the aerodynamic surface of the wings such that the flies had to actively modify their wing-stroke kinematics to maintain straight flight on the magnetic tether. Flies exhibit such modification, but the control is compromised in the dark, indicating that the visual system does provide feedback for flight stability at lower angular velocities, to which the haltere system is less sensitive. Cutting the wing surface disrupted the time course of the saccades, indicating that although flies employ sensory feedback to modulate saccade dynamics, it is not precise or fast enough to compensate for large changes in wing efficacy.
Sensorimotor control during isothermal tracking in Caenorhabditis elegans
Authors: Luo Linjiao , Clark Damon A. , Biron David , Mahadevan L. , Samuel Aravinthan D. T.
Published: November 2006

In order to purposefully navigate their environments, animals rely on precise coordination between their sensory and motor systems. The integrated performance of circuits for sensorimotor control may be analyzed by quantifying an animal's motile behavior in defined sensory environments. Here,we analyze the ability of the nematode C. elegans to crawl isothermally in spatial thermal gradients by quantifying the trajectories of individual worms responding to defined spatiotemporal thermal gradients. We show that sensorimotor control during isothermal tracking may be summarized as a strategy in which the worm changes the curvature of its propulsive undulations in response to temperature changes measured at its head. We show that a concise mathematical model for this strategy for sensorimotor control is consistent with the exquisite stability of the worm's isothermal alignment in spatial thermal gradients as well as its more complex trajectories in spatiotemporal thermal gradients.
New cyclone separator-based prefilter design for internal combustion engine applications. Part 1: Experiments and simulation
Authors: Madhusudhan K , Narasimhan M V , Ravikrishna R V
Published: November 2006

A new design of a cyclone separator-based prefilter is proposed for applications in air filtration for tractor engines and other earth-moving equipment. This design differs from the conventional prefilter in having a unidirectional flow. As a consequence, the new design offers much lower pressure loss when compared with the conventional design. A model of the new design is fabricated, and experiments were conducted to evaluate pressure loss and dust collection efficiency. Results show that the new cyclone separator is better in terms of pressure drop and dust collection efficiency when compared with the conventional design Computational fluid dynamic simulations of the two-phase flow were performed using FLUENT, and the predictions are validated with the experimental data.
Measurement and monitoring of hard disk drive spindle motor bearing parameters using position error signal
Authors: Hredzak B , Guo G , Zhang J
Published: November 2006

Current methods used for the measurement of stiffness and damping of spindle motor bearings used in hard disk drives use a vibration base driven by an external actuator. Acceleration sensors and displacement sensors installed onto the vibration base are then used to measure the acceleration and the spindle runout, respectively. Outputs from these sensors are analysed and used for the calculation of the stiffness and damping. The method, used for direct measurement and monitoring of total stiffness and damping, and proposed in this article does not require the use of any additional external sensors, neither does it require a vibration base driven by an external actuator. Vibration is generated by introducing a known value of imbalance onto the spindle motor. The vibration generated is then measured by reading and analysing the position error signal written on the disk surface and subsequently, used to calculate the total stiffness and damping. Experimental results verifying the proposed method are presented.
Analysis of vibration levels of large structural system with recursive component mode synthesis method: Theory and convergence
Authors: Kim C W
Published: November 2006

The component mode synthesis (CMS) method has been extensively used in industries. However, industry finite-element (FE) models need a more efficient CMS method for satisfactory performance since the size of FE models needs to be increased for a more accurate analysis. Recently, the recursive component mode synthesis (RCMS) method was introduced to solve large-scale eigenvalue problem efficiently. This article focuses on the convergence of the RCMS method with respect to different parameters, and evaluates the accuracy and performance compared with the Lanczos method.
Novel die-sinking micro-electro discharge machining process using microelectromechanical systems technology
Authors: Li J-B , Jiang K , Davies G J
Published: November 2006

A novel die-sinking micro-electro discharge machining (EDM) process is presented for volume fabrication of metallic microcomponents. In the process, a high-precision silicon electrode is fabricated using deep reactive ion etching (DRIE) process of microelectromechanical systems (MEMS) technology and then coated with a thin layer of copper to increase the conductivity. The metalized Si electrode is used in the EDM process to manufacture metallic microcomponents by imprinting the electrode onto a flat metallic surface. The two main advantages of this process are that it enables the fabrication of metallic microdevices and reduces manufacturing cost and time. The development of the new EDM process is described. A silicon component was produced using the Surface Technology Systems plasma etcher and the DRIE process. Such components can be manufactured with a precision in nanometres. The minimum feature of the component is 50 μm. In the experiments, the Si component was coated with copper and then used as the electrode on an EDM machine of 1 μm resolution. In the manufacturing process, 130 V and 0.2 A currents were used for a period of 5 min. The SEM images of the resulting device show clear etched areas, and the electric discharge wave chart indicates a good fabrication condition. The experimental results have been analysed and the new micro-EDM process is found to be able to fabricate 25 μm features.
RULES-F: A fuzzy inductive learning algorithm
Authors: Pham D T , Bigot S , Dimov S S
Published: November 2006

Current inductive learning algorithms have difficulties handling attributes with numerical values. This paper presents RULES-F, a new fuzzy inductive learning algorithm in the RULES family, which integrates the capabilities and performance of a good inductive learning algorithm for classification applications with the ability to create accurate and compact fuzzy models for the generation of numerical outputs. The performance of RULES-F in two simulated control applications involving numerical output parameters is demonstrated and compared with that of the well-known fuzzy rule induction algorithm by Wang and Mendel.
Acoustical feature extraction of rotating machinery with combined wave superposition and blind source separation
Authors: Xue W F , Chen J , Li J Q , Liu X F
Published: November 2006

As the result of vibration emission in air, machine sound signal carries affluent information about the working condition of machine and it can be used to make mechanical fault diagnosis. The fundamental problems with fault diagnosis are the estimation of the number of sound sources and the localization of sound sources. The wave superposition can be employed to identify and locate sound sources, which is based on the idea that an acoustic radiator can be approximated and represented by the sum of the fields due to a finite number of interior point sources. But, in practice, a large number of measurements must be used in order to achieve a desired resolution, which makes the reconstruction process very time-consuming and expensive. In this paper, a combined wave superposition method has been developed reconstruct to acoustic radiation from machine acoustical signals. This method combines the advantages of both the wave superposition and Helmholtz equationleast squares methods, and it allows for reconstruction of the acoustic field from an arbitrary object with relatively few measurements, thus significantly enhancing the reconstruction efficiency. After sound source localization, the blind source separation (BSS) is proposed to extract acoustical feature from the mixed measuring sound signals. In a semi-anechoic chamber, a cross-planar microphone array, which consists of 29 microphones, was successfully applied to obtain the two-dimensional mapping of the sound sources. The location, the sound pressure, and the properties in frequency domain of the sound sources can be found through this method precisely. The experimental results demonstrate that the methods presented can potentially become an acoustical diagnosis tool.
Association Genetics in Pinus taeda L. I. Wood Property Traits
Authors: González-Martínez Santiago C , Wheeler Nicholas C , Ersoz Elhan , Nelson C Dana , Neale David B
Published: November 2006

Genetic association is a powerful method for dissecting complex adaptive traits due to (i) fine-scale mapping resulting from historical recombination, (ii) wide coverage of phenotypic and genotypic variation within a single experiment, and (iii) the simultaneous discovery of loci and alleles. In this article, genetic association among single nucleotide polymorphisms (58 SNPs) from 20 wood- and drought-related candidate genes and an array of wood property traits with evolutionary and commercial importance, namely, earlywood and latewood specific gravity, percentage of latewood, earlywood microfibril angle, and wood chemistry (lignin and cellulose content), was tested using mixed linear models (MLMs) that account for relatedness among individuals by using a pairwise kinship matrix. Population structure, a common systematic bias in association studies, was assessed using 22 nuclear microsatellites. Different phenotype:genotype associations were found, some of them confirming previous evidence from collocation of QTL and genes in linkage maps (for example, 4cl and percentage of latewood) and two that involve nonsynonymous polymorphisms (cad SNP M28 with earlywood specific gravity and 4cl SNP M7 with percentage of latewood). The strongest genetic association found in this study was between allelic variation in α-tubulin, a gene involved in the formation of cortical microtubules, and earlywood microfibril angle. Intragenic LD decays rapidly in conifers; thus SNPs showing genetic association are likely to be located in close proximity to the causative polymorphisms. This first multigene association genetic study in forest trees has shown the feasibility of candidate gene strategies for dissecting complex adaptive traits, provided that genes belonging to key pathways and appropriate statistical tools are used. This approach is of particular utility in species such as conifers, where genomewide strategies are limited by their large genomes.
Multilevel Selection 1: Quantitative Genetics of Inheritance and Response to Selection
Authors: Bijma Piter , Muir William M , Van Arendonk Johan A M
Published: November 2006

Interaction among individuals is universal, both in animals and in plants, and substantially affects evolution of natural populations and responses to artificial selection in agriculture. Although quantitative genetics has successfully been applied to many traits, it does not provide a general theory accounting for interaction among individuals and selection acting on multiple levels. Consequently, current quantitative genetic theory fails to explain why some traits do not respond to selection among individuals, but respond greatly to selection among groups. Understanding the full impacts of heritable interactions on the outcomes of selection requires a quantitative genetic framework including all levels of selection and relatedness. Here we present such a framework and provide expressions for the response to selection. Results show that interaction among individuals may create substantial heritable variation, which is hidden to classical analyses. Selection acting on higher levels of organization captures this hidden variation and therefore always yields positive response, whereas individual selection may yield response in the opposite direction. Our work provides testable predictions of response to multilevel selection and reduces to classical theory in the absence of interaction. Statistical methodology provided elsewhere enables empirical application of our work to both natural and domestic populations.
Multilevel Selection 2: Estimating the Genetic Parameters Determining Inheritance and Response to Selection
Authors: Bijma Piter , Muir William M , Ellen Esther D , Wolf Jason B , Van Arendonk Johan A M
Published: November 2006

Interactions among individuals are universal, both in animals and in plants and in natural as well as domestic populations. Understanding the consequences of these interactions for the evolution of populations by either natural or artificial selection requires knowledge of the heritable components underlying them. Here we present statistical methodology to estimate the genetic parameters determining response to multilevel selection of traits affected by interactions among individuals in general populations. We apply these methods to obtain estimates of genetic parameters for survival days in a population of layer chickens with high mortality due to pecking behavior. We find that heritable variation is threefold greater than that obtained from classical analyses, meaning that two-thirds of the full heritable variation is hidden to classical analysis due to social interactions. As a consequence, predicted responses to multilevel selection applied to this population are threefold greater than classical predictions. This work, combined with the quantitative genetic theory for response to multilevel selection presented in an accompanying article in this issue, enables the design of selection programs to effectively reduce competitive interactions in livestock and plants and the prediction of the effects of social interactions on evolution in natural populations undergoing multilevel selection.
Fine Mapping Reveals Sex Bias in Quantitative Trait Loci Affecting Growth, Skeletal Size and Obesity-Related Traits on Mouse Chromosomes 2 and 11
Authors: Farber Charles R , Medrano Juan F
Published: November 2006

Previous speed congenic analysis has suggested that the expression of growth and obesity quantitative trait loci (QTL) on distal mouse chromosomes (MMU) 2 and 11, segregating between the CAST/EiJ (CAST) and C57BL/6J-hg/hg (HG) strains, is dependent on sex. To confirm, fine map, and further evaluate QTL × sex interactions, we constructed congenic by recipient F2 crosses for the HG.CAST-(D2Mit329-D2Mit457)N(6) (HG2D) and HG.CAST-(D11Mit260-D11Mit255)N(6) (HG11) congenic strains. Over 700 F2 mice were densely genotyped and phenotyped for a panel of 40 body and organ weight, skeletal length, and obesity-related traits at 9 weeks of age. Linkage analysis revealed 20 QTL affecting a representative subset of phenotypes in HG2DF2 and HG11F2 mice. The effect of sex was quantified by comparing two linear models: the first model included sex as an additive covariate and the second incorporated sex as an additive and an interactive covariate. Of the 20 QTL, 8 were sex biased, sex specific, or sex antagonistic. Most traits were regulated by single QTL; however, two closely linked loci were identified for five traits in HG2DF2 mice. Additionally, the confidence intervals for most QTL were significantly reduced relative to the original mapping results, setting the stage for quantitative trait gene (QTG) discovery. These results highlight the importance of assessing the contribution of sex in complex trait analyses.