bluuebunny/crossref_metadata_2025 huggingface dataset:
An analysis of the contact stress distribution at the surface of the tooling during the CONFORM process
Authors: Fan Z X , Song B Y , Yun X B , Mohanraj J , Barton D C
Published: June 2009

The CONFORM continuous extrusion process provides outstanding features and the process has been widely used in non-ferrous metal production since it was invented. Although research and development has been quite extensive, theoretical analysis of the process has been based purely on the finite-element method, which is unable to give suitable analytical equations for calculating the stress distribution. Theoretical expressions for the contact stress distribution between the deforming material and the tools are derived in this article for the specific purpose of evaluating the load and power requirements of the machine. A simplified five sub-zone model is first established according to the different deformation characteristics in the different regions of the machine. Subsequently theoretical solutions are obtained based on simplified plasticity analysis and finally expressions are derived that can be used for calculating the load acting on the extrusion wheel and shoe. In addition, experimental verification of the theoretical results is reported.
Study of an axial-type fan design technique using an optimization method
Authors: Cho C-H , Cho S-Y , Ahn K-Y , Kim Y-C
Published: June 2009

A robust axial-type fan design technique is developed by using an optimization method based on the gradient method. A three-dimensional fan blade was initially designed by stacking several two-dimensional (2D) blade profiles along the spanwise direction. These 2D blade profiles were designed using the free-vortex method and profile parameters such as the incidence, deviation, camber, and so on. The initial fan blade adopts 13 design variables to improve the target value of the fan efficiency or the total pressure. These design variables are used to control the rotor and stator profile for obtaining a better target value. In this study, fan efficiency is chosen as a target objective variable to be maximized, and the total and static pressure on the design point are applied as constraints. These procedures are applied to the design of an axial-type fan that must operate at a mass flowrate of 8.37 kg/s with a minimum total pressure rise of 670 Pa. The optimized fan not only increases the efficiency by 2.9 per cent but also satisfies the required total and static pressure conditions compared with the initially designed fan performance. The optimized fan performance agrees with the experimental results; therefore, this fan design technique can be applied to improve the efficiency and the operating pressure of axial-type fans.
Criticality determination based on failure records for decision-making in the overhead contact line system
Authors: Duque O , Zorita A L , García-Escudero L A , Fernández M A
Published: June 2009

In this article, a new methodology to determine the criticality of the components of the overhead contact line (OCL) system by means of a component criticality index is proposed. The methodology is based on classic failure mode and effects analysis (FMEA) but adapted to its application on this system, with characteristics far from industrial systems where FMEA was developed. The procedure is focused on the analysis of the system's operating history with the important advantage that the subjectivity of the usual procedures is reduced. This methodology has proved to be very useful when applied to decision-making and for establishing maintenance frequencies of the elements of the OCL of the Spanish railway network, and it could also be applied to other kind of large-scale distributed systems.
Cone invariance and rendezvous of multiple agents
Authors: Bhattacharya R , Tiwari A , Fung J , Murray R M
Published: June 2009

In this article is presented a dynamical systems framework for analysing multi-agent rendezvous problems and characterize the dynamical behaviour of the collective system. Recently, the problem of rendezvous has been addressed considerably in the graph theoretic framework, which is strongly based on the communication aspects of the problem. The proposed approach is based on the set invariance theory and focusses on how to generate feedback between the vehicles, a key part of the rendezvous problem. The rendezvous problem is defined on the positions of the agents and the dynamics is modelled as linear first-order systems. These algorithms have also been applied to non-linear first-order systems. The rendezvous problem in the framework of cooperative and competitive dynamical systems is analysed that has had some remarkable applications to biological sciences. Cooperative and competitive dynamical systems are shown to generate monotone flows by the classical Muller—Kamke theorem, which is analysed using the set invariance theory. In this article, equivalence between the rendezvous problem and invariance of an appropriately defined cone is established. The problem of rendezvous is cast as a stabilization problem, with a the set of constraints on the trajectories of the agents defined on the phase plane. The n-agent rendezvous problem is formulated as an ellipsoidal cone invariance problem in the n-dimensional phase space. Theoretical results based on set invariance theory and monotone dynamical systems are developed. The necessary and sufficient conditions for rendezvous of linear systems are presented in the form of linear matrix inequalities. These conditions are also interpreted in the Lyapunov framework using multiple Lyapunov functions. Numerical examples that demonstrate application are also presented.
A new non-linear algorithm for complete pre-flight calibration of magnetometers in the geomagnetic field domain
Authors: Ghanbarpour Asl H , Pourtakdoust S H , Samani M
Published: June 2009

A new algorithm for complete pre-flight calibration of triple magnetometers is developed. The traditional approach for calibrating these sensors are based on a cumbersome procedure called ‘swing’ that involves levelling and rotating the vehicle containing the magnetometers through a series of known headings. Application of such a procedure is difficult and costly. Recently, new approaches have been developed to calibrate magnetometers without the need of attitude information. Such methods are used mostly for the calibration of biases and scale factors. Additionally in situations where misalignment errors are also to be estimated, they are usually modelled as errors of a non-orthogonal frame relative to an orthogonal frame creating six additional unknown parameters to be estimated. The presented approach in this article utilizes a three-step algorithm to fully calibrate triple magnetometers without the need of attitude information through a batch least-square non-linear estimator. Since misalignment parameters are not all identifiable through attitude-independent techniques, the measurement equation is initially factorized such that the non-observable parameters are removed. This would allow identification of three parameters through attitude-independent techniques, while identification of the other three that require horizon information is carried out using a secondary procedure. In step one of the proposed scheme, the non-linear observation equation is transformed, via two non-linear functions, to a linear space with respect to the unknown parameters and the new unknown parameters are estimated with batch least-square estimator. In the second step, the first non-linear function is solved for nine parameters that have non-linear relationships with respect to the desired biases, scale factors, and misalignments. Subsequently, the second non-linear function is solved giving the main unknown calibration parameters in a non-physical frame. Finally, in the third step, to find the required transformation matrix between the magnetometer platform frame, the magnetometer is rotated in a horizontal plane about x, y, and z platform axis, respectively. Assuming that the vertical component of the geomagnetic field is known, the calibration parameters are next determined with respect to the platform frame utilizing the rotation matrix. The proposed three-step algorithm does not need any initial condition or iterations for convergence and more importantly does not require any attitude information for the estimation of misalignments. The algorithm is simulated to validate the performance of the estimator using experimental data gathered from a magnetometer triad. Results show relative superiority when compared with those of the two-step algorithm with heading errors of the order of 0.5 to 1 degrees.
Experimental study of atomization effects on two-phase pulse detonation engines
Authors: Wang Z , Yan C , Fan W , Zheng L
Published: June 2009

This article presents some results dealing with effects of atomizer types on mean droplet size and pulse detonation engine (PDE) performance. The plain-orifice injector and twin-fluid air-assist atomizer were located at the head-end of a PDE mockup to inject gasoline, which was used as the liquid fuel. A particle size meter based on laser light scattering was employed to measure mean droplet size. The curves of mean droplet size versus gasoline flux and gasoline/air ratio are obtained. The twin-fluid air-assist atomizer can produce much smaller mean droplet size than the plain-orifice injector. The air was injected into the mixing chamber through tangential ports that gave the fuel a high angular velocity, thereby creating smaller droplets. To observe the effect of gasoline droplet size on PDE, the proof-of-principle experiments of PDE were carried out. The experimental results indicated that the equivalence ratio lower limits decreased and the upper limits increased as the gasoline droplet size decreased when air-assist atomizer was used instead of plain-orifice injector. That meant the equivalence ratio limits turned wide as the gasoline droplet size decreased. Meanwhile, the optimum equivalence ratio decreased as the gasoline droplet size decreased. The smaller the droplet size, the lower the optimum equivalence ratio required to stabilize detonation. As the operation frequency increased, the equivalence ratio limit became narrow and the difference of optimum equivalence ratio between the air-assist atomizer and the plain-orifice injector decreased. Furthermore, droplet size of liquid fuel had a considerable effect on the wave speed. The wave speed increased as the gasoline droplet size decreased, while still being lower than the gas-phase Chapman—Jouguet detonation velocity.
Design and analysis of a rudderless aeroelastic fin
Authors: Trapani M , Guo S
Published: June 2009

This article presents a research of a gapless and rudderless aeroelastic fin (GRAF) structure. It includes conceptual design, structural modelling, and performance analysis for a small unmanned aerial vehicle (UAV) fin. Instead of the conventional design of rigid fin with a hinged rudder for the UAV, the GRAF is designed as a unitized structural system integrating three primary components: a flexible skin reinforced by ribs and stringers, a flexible trailing edge (TE) section, and a rigid shaft connecting the ribs and actuators at the root. There are four novel design features in the GRAF to enhance its aeroelastic effect and performance. They include an activated shaft spar, a flexible TE section with an elastic TE and leading edge, an L-shape stringer for reinforcement and part of the TE skin actuation mechanism, and a compliant slot at the GRAF root mounting. A small UAV was taken as an example to compare the directional stability and controllability of the GRAF with the conventional fin. The results have shown that the GRAF satisfies the design and performance requirements although the divergence and flutter margin is slightly smaller than the conventional design.
An interesting fact regarding the Routh table
Authors: Landers R
Published: June 2009

The Routh table is a powerful analysis tool used to determine how many roots of a given polynomial have negative, zero, and positive real parts. A special case occurs when a row of zeros is encountered. This indicates an even polynomial may be factored from the given polynomial. It is well known that the even polynomial is in the row above the row of zeros. In this technical note it will be shown that the even polynomial may be factored from all of the polynomials in the rows above the row of zeros.
Comparative evaluation of dry sliding wear behaviour of plasma transferred arc hardfaced surfaces by the pin-on-roller method
Authors: Ramachandran C S , Balasubramanian V , Varahamoorthy R
Published: June 2009

Dry sliding wear occurs when two bodies are in sliding contact. During the process of sliding, fragments may be pulled out from one surface and they may stick on to the other. Later on, these may get transferred back or may become loose wear particles. This article reports the effects of different experimental conditions on the dry sliding wear behaviour of iron-based alloy (stainless steel), cobalt-based alloy (stellite), and nickel-based alloy (colmonoy) surfaces produced by the plasma transferred arc hardfacing process. The wear test was conducted using a pin-on-roller wear testing machine. The dry sliding wear behaviour of the hardfaced surfaces was compared and it was found that the wear resistance of nickel-based alloy is 5 times higher than the base metal. Similarly, cobalt-based alloy exhibits 3 times higher wear resistance and iron-based alloy shows 1.5 times higher wear resistance compared to base metal.
The performance of a porous ceramic hydrostatic journal bearing
Authors: Durazo-Cardenas I S , Corbett J , Stephenson D J
Published: June 2009

The performance of a porous-ceramic hydrostatic journal bearing manufactured by the starch consolidation (SC) technique has been examined using a highly instrumented test rig. The results have been compared with those of a 5-recess hydrostatic bearing of the same size and comparable design, under the same testing conditions. The SC porous-ceramic bearing showed an improved performance over the conventional hydrostatic bearing. Static and rotational stiffness were 95 per cent and over 150 per cent higher, respectively. In addition, the porous ceramic bearing exhibited a more economic performance with a 64 per cent lower flowrate and pumping power than the hydrostatic bearing. In terms of heat generation, the porous ceramic bearing showed 50 per cent lower temperature rise.
Investigation on rolling contact fatigue and wear properties of railway rails
Authors: Wang W J , Zhong W , Guo J , Liu Q Y , Zhu M H , Zhou Z R
Published: June 2009

The rolling wear tests of rail material were conducted under unlubricated condition using a JD-1 wheel/rail simulation facility. The fatigue damage and wear behaviours of rail rollers were investigated in detail by examining the microhardness, wear volume, and wear scars using optical microscopy and scanning electronic microscopy. The results indicate that wear volume of a rail roller increases rapidly with the increase of axle load and decrease of curve radius. Wear volume of U71Mn rail is bigger than that of PD3 rail. It is observed that PD3 rail roller has some fatigue microcracks on the surface of wear scar. Furthermore, the microcrack propagates along depth direction with an angle of 15–30°. By comparison, U71Mn material has better fatigue resistance performance. The results indicate when the wear is serious, the fatigue damage is relatively slight. The relationship between fatigue crack damage and wear seems as competitive and restrictive coupling mechanisms.
Erosion characteristics in ultrasonic cavitation
Authors: Jing Luo , Jian Li
Published: June 2009

Cavitation erosion is accomplished by a magnetostrictive transducer at different experiment input powers using column steel samples. The distribution characteristics of bubbles on the emitting surfaces are observed at different times. The photo records show that ultrasonic bubbles distributed on the emitting surface will converge and form some interesting patterns of branches, which varies with the increase of time and different powers. Such phenomena are explained by the theory of viscous fingers effect and the mode of diffusion limited aggregation. The cavitation erosion appearances of the samples are measured by a three-dimensional (3D) surface measuring system. The results show that the erosion degree and characteristic on the sample emitting surface are dominated by the input powers. It is concluded that the cavitation erosion appearance is decided by the distribution structure of bubbles and the degree of cavitation erosion is influenced by the density of bubble group and the thickness of the bubble layer.
Mechanical and tribological properties of titanium reinforced polybenzimidazole
Authors: Lu Y , Chen J , Cui H , Zhou H
Published: June 2009

Polybenzimidazole (PBI) was synthesized by liquid condensation and its molecular weight was measured by gel permeation chromatography (GPC). The resulting PBI product was used as the polymer matrix to prepare composites reinforced with titanium (abridged as Ti/PBI) using hot-press sintering in vacuum. A scanning electron microscope (SEM) was used to observe the morphology of the composite samples, while a ball-on-disc friction and wear tester were performed to evaluate tribological properties of the bulk PBI composites. The introduction of Ti as the reinforcing agent contributed to improving the mechanical properties of the PBI composites. Moreover, the Ti/PBI composites had small friction coefficients as slid against AISI-1045 steel in a ball-on-disc configuration, and the friction coefficients decreased with increasing temperature. However, the wear resistance of PBI was reduced slightly by incorporation of the Ti powders, and increased wear rates were recorded for Ti/PBI composites at elevated temperatures.
Micropolar fluid squeeze film lubrication of short partial porous journal bearings
Authors: Naduvinamani N B , Huggi S S
Published: June 2009

On the basis of Eringen's micropolar fluid theory, a theoretical analysis of hydrodynamic squeeze film behaviour for short partial porous journal bearings lubricated by micropolar fluids is presented in this article. To take into account the micropolar effects because of the lubricant containing additives or suspended particles in a short partial porous journal bearing, the modified Reynolds equation governing the film pressure is derived. Expressions for the squeeze film pressure and load-carrying capacity are obtained. The first-order non-linear equation for the time-height relation is solved numerically by using the Runge—Kutta method. From the results obtained, it is observed that, the effect of micropolar fluid is to increase the load-carrying capacity and to lengthen the squeeze film time as compared to the corresponding Newtonian case. The effect of permeability is to reduce the load-carrying capacity and the squeeze film time as compared to the corresponding solid case.
Weld surfacing of aluminium alloy by Ni—Cr base alloys
Authors: Jagannadham D , Dwivedi D K , Ghosh P K
Published: June 2009

This article describes the microstructure, microhardness, and the abrasive wear behaviour of the Ni—Cr base alloy overlays deposited on the Al—Zn—Mg alloy (7039) substrate by the shielded metal arc welding process. The weld overlays were deposited by using four levels of the welding current in the range from 110 to 140A. Abrasive wear tests were carried out by using a pin-on-disc wear tester under a spiral wear track. Wear tests were carried out using three normal loads (5N, 10N, and 15N) and abrasives of three grit sizes (120, 320, and 600 grade). Scanning electron microscopy, X-ray diffraction, and the energy dispersive analysis of X-rays studies were performed on the weld overlay to characterize the microstructure, composition, and phase analysis. It was found that from the microstructure point of view, three different zones are formed in the weld overlays. These zones exhibited significant variation in terms of the nickel and the aluminium content in the micro-constituents. The microhardness has been found to decrease from the top surface of the weld overlays to the base metal.
Synthesis and Application of 2′-ara-Fluoroguanosine-substituted Cap Analog
Authors: Kore Anilkumar R , Charles Irudaya , Shanmugasundaram Muthian
Published: June 2009

An efficient synthesis of new cap analog bearing 2′-ara-fluoro-substitution i.e. m7,2′(ara)FG[5′]ppp[5′]G is reported. The structure of this cap analog has been confirmed by 1H, 31P, and 19F NMR and MS data. The effect of the 2′-ara-fluoroguanosine-substituted cap analog has been evaluated with respect to its capping efficiency, in vitro T7 RNA polymerase transcription, intracellular stability, and translation activity in cultured HeLa cells using standard cap m7G[5′]ppp[5′]G as a control.
α-Amidobenzylation of Aryl and Alkenyl Halides via Palladium-catalyzed Suzuki–Miyaura Coupling with α-(Acylamino)benzylboronic Esters
Authors: Ohmura Toshimichi , Awano Tomotsugu , Suginome Michinori
Published: June 2009

The Suzuki–Miyaura coupling of α-(acetylamino)benzylboronic esters with aryl and alkenyl halides has been achieved using a Pd/P(t-Bu)3 catalyst with KF and H2O in 1,4-dioxane, giving α-substituted benzylamines in high yields.
Mass Spectrometry of Metal Complexes of Bis-Quinolizidine Alkaloids: Electron Ionization and Fast Atom Bombardment Mass Spectral Study of Copper(II) (–)-Sparteine and (–)-α-Isosparteine Complexes
Authors: Jasiewicz Beata , Wyrzykiewicz Elżbieta
Published: June 2009

The electron ionization (EI) and fast atom bombardment (FAB) mass spectral fragmentations of ten copper(II) dichloride (dibromide, diformate, diacetate and dithiocyanate) complexes of (–)-sparteine and (–)-α-isosparteine were investigated. Fragmentation pathways, elucidation of which was assisted by accurate mass measurements and metastable transitions (EI-MS), as well as FAB/collision-induced dissociation (CID) mass spectral measurements are discussed. The data obtained create the basis for the differentiation of the ligand (sparteine or α-isosparteine) in the investigated complexes. The comparison of the results with those obtained previously for corresponding zinc(II) complexes forms the basis for the differentiation of metals in these compounds. The results show that both EI-MS and FAB-MS are very useful tools for the differentiation of ligands, as well as metals in the series of Zn(II) and Cu(II) dichloride (dibromide, diacetate, diformate, dithioacetate) complexes of (–)-sparteine and (–)-α-isosparteine.
Adverse Effects of Antiretrovirals in HIV-Infected Pregnant Women
Authors: Zuk Dalyce M , Hughes Christine A , Foisy Michelle Marie , Robinson Joan L , Singh Ameeta E , Houston Stan
Published: June 2009

Background

Current guidelines for the use of antiretroviral (ARV) therapy during pregnancy recommend that women be offered treatment with combination ARV therapy used in nonpregnant HIV-infected individuals. It is unclear whether the risk of ARV-related adverse drug reactions (ADRs) is increased during pregnancy.

Objective

To evaluate the frequency and severity of ADRs likely caused by ARV therapy in pregnant women who are HIV-positive.

Methods

A retrospective analysis of HIV-infected women who received ARV therapy during pregnancy and delivered between January 1997 and February 2006 was conducted. Incidence of maternal ADRs was determined through evaluation of laboratory findings, documented physical examinations, and patient self-reports. An AIDS Clinical Trials Group severity grading scale was applied to the ADRs. Cause-effect relationship was adjudicated based on the Naranjo probability scale and, if causality was found, that information was included.

Results

There were 103 women who accounted for 133 pregnancies that resulted in deliveries. Of the 111 pregnancies in which treatment was received, regimens included 26 nucleoside reverse transcriptase inhibitor monotherapy, 40 nonnucleoside reverse transcriptase inhibitor (NNRTI)–based, 44 protease inhibitor (PI)–based, and 1 PI/NNRTI combination therapy. Ninety-eight ADRs were documented in 49 pregnancies. The most common ADRs were gastrointestinal (n = 48), followed by central nervous system symptoms (n = 15), anemia (n = 15), elevated liver/pancreatic enzyme levels (n = 11), and cutaneous reactions (n = 8). Severe ADRs included elevations in liver/pancreatic enzymes (n = 3), nausea and vomiting (n = 3), and anemia (n = 2). Seven women required a change in therapy due to an ADR.

Conclusions

Approximately 7 ADRs were reported for every 10 pregnancies in this cohort. Most ADRs were mild to moderate. Short exposure times in most women (second and third trimester) may have accounted for the lack of long-term toxicities. Although ADRs did not pose a major barrier to use of ARVs in pregnancy, close monitoring of pregnant women receiving ARV therapy continues to be warranted.
Resistance of thermo-hygro-mechanically (THM) densified wood to degradation by white rot fungi
Authors: Skyba Oleksandr , Niemz Peter , Schwarze Francis W.M.R.
Published: June 2009

Colonisation and degradation by the white rot fungi, Trametes versicolor and T. pubescens, were studied in wood of Norway spruce and beech subjected to three different treatments: (1) hygro-thermal treatment (160°C and 180°C), (2) mechanical densification, and (3) thermo-hygro-mechanical (THM) treatment including densification and post-treatment at different temperatures (140°C, 160°C and 180°C). The weight losses induced by the fungi were lowest in THM-densified woods. However, volume related numerical indicators for decay susceptibility did not show any significant improvements of THM-densified woods against both fungi. Analysis of the chemical composition of treated wood species revealed slight alterations in the content of polysaccharides and lignin. White rot fungi circumvented conditions restricting hyphal growth within the occluded tracheid lumina by hyphal tunnelling in the secondary walls of fibre tracheids in beech or by forming bore holes that transversally penetrated cell walls of earlywood tracheids in THM-densified spruce. The studies indicate that THM-densified beech and Norway spruce wood may have some potential in utility class 3 but are inappropriate for use in utility class 4.
Reconstruction of 3D images of internal log characteristics by means of successive 2D log computed tomography images
Authors: Wei Qiang , Zhang Shu Yin , Chui Ying Hei , Leblon Brigitte
Published: June 2009

Although three-dimensional (3D) internal log images are useful to wood scientists for assessing internal log features, little work has been carried out on this subject. The aim of this paper was to demonstrate how two-dimensional (2D) log images may be combined to create 3D images of internal log features. The selected log features include heartwood, sapwood, bark, and knots in a sugar maple log and a black spruce log. The 2D cross-sectional images of the logs were acquired through computed tomography (CT) scanning. For each log, 72 successive 2D cross-sectional CT images of the log were employed to create the corresponding 3D internal log images based on the marching cubes algorithm. The results suggest that the proposed method can produce clear 3D images for each selected internal log features in sugar maple and black spruce. The accuracy analysis of the 3D reconstruction is still a huge challenge and should be fully investigated in future work.
A randomized trial of cerclage vs. 17 α-hydroxyprogesterone caproate for treatment of short cervix
Authors: Keeler Sean M. , Kiefer Daniel , Rochon Meredith , Quinones Joanne N. , Novetsky Akiva P. , Rust Orion
Published: June 2009

Objective: To determine pregnancy outcome in patients with short cervix on transvaginal ultrasound between 16 and 24 weeks' gestation treated with McDonald cerclage compared to weekly intramuscular injections of 17 α-hydroxyprogesterone caproate (17OHP-C).

Methods: From November 2003 through December 2006, asymptomatic, singleton pregnancies were screened with transvaginal ultrasound between 16–24 weeks' gestation. Patients with a cervical length (CL) ≤25 mm were offered enrollment. Patients were randomly assigned to treatment with McDonald cerclage or weekly intramuscular injections of 17OHP-C. The primary outcome was spontaneous preterm birth (PTB) prior to 35 weeks' gestation.

Results: Seventy-nine patients met inclusion criteria; 42 were randomly assigned to the cerclage and 37 to 17OHP-C. Spontaneous PTB prior to 35 weeks' gestation occurred in 16/42 (38.1%) of the cerclage group and in 16/37 (43.2%) of the 17OHP-C group (relative risk, 1.14 95% CI, 0.67, 1.93). A post hoc analysis of patients with a prior PTB showed no difference in spontaneous PTB <35 weeks between groups. A similar analysis of patients with a CL≤15 mm showed a reduction in spontaneous PTB <35 weeks in the cerclage group (relative risk 0.48, 0.24–0.97).

Conclusion: Women with CL ≤25 mm in the second-trimester appear to have similar risks of delivering prior to 35 weeks' gestation when treated with 17OHP-C or McDonald cerclage. However, cerclage may be more effective in preventing spontaneous PTB in women with CL≤15 mm.
Grasping activity in utero: a significant indicator of fetal behavior (The role of the grasping reflex in fetal ethology)
Authors: Jakobovits Ákos A.
Published: June 2009

No abstract available
Long chain polyunsaturated fatty acids in mothers and term babies
Authors: Kilari Anitha S. , Mehendale Savita S. , Dangat Kamini D. , Yadav Hemlata R. , Kulakarni Asmita V. , Dhobale Madhavi V. , Taralekar Vaishali S. , Joshi Sadhana R.
Published: June 2009

Aim: To establish the levels of docosahexaenoic acid (DHA) and arachidonic acid (AA) in both plasma and erythrocytes of maternal and cord blood as well as in breast milk of mothers delivering babies at term.

Methods: A total of 148 mothers delivering babies at term were recruited from Bharati Medical Hospital, Pune, India.

Results: Levels of DHA and AA in both plasma and erythrocyte were higher in cord blood compared to levels in maternal blood (P<0.001). Maternal plasma and erythrocyte DHA levels had a positive association with the respective levels in cord blood (P<0.001). However, such an association was not seen for AA levels. Maternal plasma omega 3 and omega 6 fatty acids were positively associated with the respective milk fatty acids (P<0.01).

Conclusions: Our results indicate that milk long-chain polyunsaturated fatty acids (LCPUFA) status reflects the concentrations of maternal LCPUFA in women delivering babies at term. Improving the maternal LCPUFA status throughout pregnancy and lactation may improve the milk LCPUFA status and ultimately benefit the infant.
When uncertainty generates more anxiety than severity: the prenatal experience with cystic adenomatoid malformation of the lung
Authors: Aite Lucia , Zaccara Antonio , Trucchi Alessandro , Brizzi Christiana , Nahom Antonella , Iacobelli Barbara , Capolupo Irma , Bagolan Pietro
Published: June 2009

Aim: To assess reasons for higher levels of anxiety generated by prenatal counselling of a condition with good outcome such as cystic adenomatoid malformation (CCAM) of the lung compared to a life-threatening malformation such as congenital diaphragmatic hernia (CDH).

Materials and methods: The Spielberger State-Trait Anxiety Inventory (STAI-S) was used to measure anxiety in two groups of mothers carrying a fetus with the respective malformation.

Results: Forty-four mothers completed the questionnaire (CCAM, n=21 and CDH, n=23). Before consultation, the mean STAI-S scores in the CCAM group (44.80±5.92) and in CDH group (44.05±4.96) were not significantly different but was significantly reduced in both groups after consultation (CCAM 44.80 vs. 41.60, P=0.014 and CDH 44.05 vs. 34.35, P=0.0001). The groups were not significantly different regarding gestational age at diagnosis.

Conclusions: After initial prenatal counselling, uncertainty about prenatal outcome and lack of defined management plans in CCAM seems to be more important than higher mortality rate occurring in CDH.
Effect of exogenous surfactant therapy on levels of pulmonary surfactant proteins A and D in preterm infants with respiratory distress syndrome
Authors: Bae Young Min , Bae Chong-Woo , Oh Myung Ho , Lee Sang Han , Woo Kee Min , Jung Keum Bun
Published: June 2009

Objectives:To examine whether exogenous pulmonary surfactants (exPS) substitute for or merely supplement endogenous pulmonary surfactants (enPS) by looking at sequential changes in the surfactant proteins (SP) SP-A and SP-D in alveolar pools.

Methods:Fourteen preterm infants with RDS treated with an artificial surfactant were compared to five normal-term infants without RDS who were treated with artificial ventilation at birth.

Results:Immediately after birth, SP-A and SP-D were essentially absent in the alveolar pools of the RDS group, but were present at normal levels in the controls. Treatment with exPS apparently stimulated enPS production.

Conclusions:In infants who responded well to exPS therapy, the SP concentration reached essentially normal levels within 48–72 h after birth.
Chronic Nicotine Blunts Hypoxic Sensitivity in Perinatal Rat Adrenal Chromaffin Cells via Upregulation of KATPChannels: Role of α7 Nicotinic Acetylcholine Receptor and Hypoxia-Inducible Factor-2α
Authors: Buttigieg Josef , Brown Stephen , Holloway Alison C. , Nurse Colin A.
Published: June 2009

Fetal nicotine exposure blunts hypoxia-induced catecholamine secretion from neonatal adrenomedullary chromaffin cells (AMCs), providing a link between maternal smoking, abnormal arousal responses, and risk of sudden infant death syndrome. Here, we show that the mechanism is attributable to upregulation of KATPchannels via stimulation of α7 nicotinic ACh receptors (AChRs). These KATPchannels open during hypoxia, thereby suppressing membrane excitability. Afterin uteroexposure to chronic nicotine, neonatal AMCs show a blunted hypoxic sensitivity as determined by inhibition of outward K+current, membrane depolarization, rise in cytosolic Ca2+, and catecholamine secretion. However, hypoxic sensitivity could be unmasked in nicotine-exposed AMCs when glibenclamide, a blocker of KATPchannels, was present. Both KATPcurrent density and KATPchannel subunit (Kir 6.2) expression were significantly enhanced in nicotine-exposed cells relative to controls. The entire sequence could be reproduced in culture by exposing neonatal rat AMCs or immortalized fetal chromaffin (MAH) cells to nicotine for ∼1 week, and was prevented by coincubation with selective blockers of α7 nicotinic AChRs. Additionally, coincubation with inhibitors of protein kinase C and CaM kinase, but not protein kinase A, prevented the effects of chronic nicotinein vitro. Interestingly, chronic nicotine failed to blunt hypoxia-evoked responses in MAH cells bearing short hairpin knockdown (>90%) of the transcription factor, hypoxia-inducible factor-2α (HIF-2α), suggesting involvement of the HIF pathway. The therapeutic potential of KATPchannel blockers was validated in experiments in which hypoxia-induced neonatal mortality in nicotine-exposed pups was significantly reduced after pretreatment with glibenclamide.
Stress Prompts Habit Behavior in Humans
Authors: Schwabe Lars , Wolf Oliver T.
Published: June 2009

Instrumental behavior can be controlled by goal-directed action–outcome and habitual stimulus–response processes that are supported by anatomically distinct brain systems. Based on previous findings showing that stress modulates the interaction of “cognitive” and “habit” memory systems, we asked in the presented study whether stress may coordinate goal-directed and habit processes in instrumental learning. For this purpose, participants were exposed to stress (socially evaluated cold pressor test) or a control condition before they were trained to perform two instrumental actions that were associated with two distinct food outcomes. After training, one of these food outcomes was selectively devalued as subjects were saturated with that food. Next, subjects were presented the two instrumental actions in extinction. Stress before training in the instrumental task rendered participants' behavior insensitive to the change in the value of the food outcomes, that is stress led to habit performance. Moreover, stress reduced subjects' explicit knowledge of the action–outcome contingencies. These results demonstrate for the first time that stress promotes habits at the expense of goal-directed performance in humans.
Stimulation of Movement in a Quiescent, Hibernation-Like Form ofCaenorhabditis elegansby Dopamine Signaling
Authors: Gaglia Marta Maria , Kenyon Cynthia
Published: June 2009

One of the characteristics of animals in hibernation is reduced behavioral activity. TheCaenorhabditis elegansdauer state is a hibernation-like state of diapause that displays a dramatic reduction in spontaneous locomotion. A similar dauer-like quiescent state is produced in adults by relatively strong mutations in the insulin/IGF-1 receptor homologdaf-2. In this study, we show that mutations affecting the neurotransmitter dopamine, which regulates voluntary movement in many organisms, can stimulate movement in dauers and dauer-like quiescent adults. Surprisingly, the movement of quiescent animals is stimulated by conditions that reduce dopamine signaling and also by conditions predicted to increase dopamine signaling. Reducing dopamine signaling is likely to stimulate movement by activating a foraging response also seen in nondauers after withdrawal of food. In contrast, the stimulation of movement by increased dopamine is much more pronounced in quiescentdaf-2(−)dauer and dauer-like adult animals than in nondauaer animals. This altered response to dopamine is primarily attributable to activity of the FOXO (forkhead box O) transcription factor DAF-16 in neurons. We suggest that dauers and dauer-like quiescent adults may have underlying changes in the dopamine system that enable them to respond differently to environmental stimulation.
Human Functional Magnetic Resonance Imaging Reveals Separation and Integration of Shape and Motion Cues in Biological Motion Processing
Authors: Jastorff Jan , Orban Guy A.
Published: June 2009

In a series of human functional magnetic resonance imaging experiments, we systematically manipulated point-light stimuli to identify the contributions of the various areas implicated in biological motion processing (for review, see Giese and Poggio, 2003). The first experiment consisted of a 2 × 2 factorial design with global shape and kinematics as factors. In two additional experiments, we investigated the contributions of local opponent motion, the complexity of the portrayed movement and a one-back task to the activation pattern. Experiment 1 revealed a clear separation between shape and motion processing, resulting in two branches of activation. A ventral region, extending from the lateral occipital sulcus to the posterior inferior temporal gyrus, showed a main effect of shape and its extension into the fusiform gyrus also an interaction. The dorsal region, including the posterior inferior temporal sulcus and the posterior superior temporal sulcus (pSTS), showed a main effect of kinematics together with an interaction. Region of interest analysis identified these interaction sites as the extrastriate and fusiform body areas (EBA and FBA). The local opponent motion cue yielded only little activation, limited to the ventral region (experiment 3). Our results suggest that the EBA and the FBA correspond to the initial stages in visual action analysis, in which the performed action is linked to the body of the actor. Moreover, experiment 2 indicates that the body areas are activated automatically even in the absence of a task, whereas other cortical areas like pSTS or frontal regions depend on the complexity of movements or task instructions for their activation.
Firing Patterns in Superior Colliculus of Head-Unrestrained Monkey during Normal and Perturbed Gaze Saccades Reveal Short-Latency Feedback and a Sluggish Rostral Shift in Activity
Authors: Choi Woo Young , Guitton Daniel
Published: June 2009

The superior colliculus (SC) encodes a saccade via the spatial position of an ensemble of active neurons on its motor map. Downstream circuits control muscles with the temporal code of firing frequency and duration. The moving hill hypothesis resolves the SC-to-brainstem spatiotemporal transformation (STT) enigma by proposing feedback to the SC which “pushes” a hill of activity (height = frequency) caudorostrally such that its instantaneous position encodes the angular error [gaze-position error (GPE)] between gaze and target. This mechanism, proposed for cat but controversial in primate, has not been tested in the head-unrestrained monkey. We do this here. During large ∼60° control gaze shifts in the dark, a hill of activity began in the caudal SC and moved rostrally, but too sluggishly to encode veridical GPE. At gaze end the peak had not reached the rostral pole and only arrived there ∼80 ms later. No moving hill accompanied ∼20° gaze shifts, in agreement with previous studies of head-fixed monkeys. To investigate feedback to the SC, we perturbed large gaze shifts producing initial and corrective gaze saccades separated by 50–800 ms of gaze immobility, the gaze plateau. Map activity was dramatically remodeled: the sluggishly moving hill stopped during the plateau, at the site encoding the corrective gaze saccade, thereby providing a tonic stationary spatially encoded memory signal of plateau GPE. A burst occurred before the corrective saccade. Conclusion: Feedback to map moves activity which encodes a low-pass filtered GPE signal, a process too slow to implement the STT but adequate for corrective gaze saccades.
Identifying Sleep Regulatory Genes Using aDrosophilaModel of Insomnia
Authors: Seugnet Laurent , Suzuki Yasuko , Thimgan Matthew , Donlea Jeff , Gimbel Sarah I. , Gottschalk Laura , Duntley Steve P. , Shaw Paul J.
Published: June 2009

Although it is widely accepted that sleep must serve an essential biological function, little is known about molecules that underlie sleep regulation. Given that insomnia is a common sleep disorder that disrupts the ability to initiate and maintain restorative sleep, a better understanding of its molecular underpinning may provide crucial insights into sleep regulatory processes. Thus, we created a line of flies using laboratory selection that share traits with human insomnia. After 60 generations,insomnia-like(ins-l) flies sleep 60 min a day, exhibit difficulty initiating sleep, difficulty maintaining sleep, and show evidence of daytime cognitive impairment.ins-lflies are also hyperactive and hyperresponsive to environmental perturbations. In addition, they have difficulty maintaining their balance, have elevated levels of dopamine, are short-lived, and show increased levels of triglycerides, cholesterol, and free fatty acids. Although their core molecular clock remains intact,ins-lflies lose their ability to sleep when placed into constant darkness. Whole-genome profiling identified genes that are modified inins-lflies. Among those differentially expressed transcripts, genes involved in metabolism, neuronal activity, and sensory perception constituted over-represented categories. We demonstrate that two of these genes are upregulated in human subjects after acute sleep deprivation. Together, these data indicate that theins-lflies are a useful tool that can be used to identify molecules important for sleep regulation and may provide insights into both the causes and long-term consequences of insomnia.
Micro-Mirror-Arrays (MMA) zur Auflösungserhöhung von OberflächenformvermessungenMicro-Mirror-Arrays (MMA) Used to Improve the Resolution of Surface Shape Measurements
Authors: Werth Nadine , Koch Alexander W.
Published: June 2009

Die Form von optisch rauen Oberflächen lässt sich mit Hilfe von Speckle-Interferometern aus variabler Messdistanz selbst in schwer zugänglichen Regionen präzise vermessen. Durch die Einbindung eines Micro-Mirror-Arrays wurde erstmals versucht, die Phasenfront der Referenzwelle variabel an messtechnisch kritische Oberflächenbereiche zu adaptieren, um die bisherigen Grenzen der Auflösbarkeit zu überwinden. Im Rahmen dieser Publikation werden erste Messresultate vorgestellt.
Deflektometrie macht der Interferometrie KonkurrenzDeflectometry Rivals Interferometry
Authors: Knauer Markus C. , Richter Claus , Hybl Odrej , Kaminski Jürgen , Faber Christian , Häusler Gerd
Published: June 2009

Die Deflektometrie ist eine in den letzten Jahren neu entwickelte Methode zur Vermessung glatter Oberflächen. Sie gestattet es, auch auf Freiformflächen Höhenvariationen im Nanometerbereich zu vermessen. Um die positiven Eigenschaften der Deflektometrie zu verstehen, betrachten wir die physikalischen Grenzen sowie informationstheoretische Aspekte. Abschließend wird die Vielseitigkeit der Deflektometrie anhand von Anwendungsbeispielen demonstriert.
Neuartige kapazitive Sensoren für die Visualisierung von MehrphasenströmungenNovel Capacitive Sensors for the Visualization of Multi-Phase Flows
Authors: da Silva Marco Jose , Thiele Sebastian , Hampel Uwe
Published: June 2009

In diesem Beitrag werden zwei neuartige bildgebende Sensoren zur Untersuchung von Mehrphasenströmungen beschrieben – der kapazitive Gittersensor und der kapazitive Flächensensor. Beide Sensoren basieren auf einer matrixförmigen Anordnung von Messelementen, mit denen die elektrische Kapazität eines umgebenden Fluides sehr schnell abgetastet wird. Dadurch sind diese Sensoren in der Lage, zeitlich und räumlich hochaufgelöste Bilder der Phasenverteilung einer Mehrphasenströmung zu erzeugen. Die Sensoren und die zugehörige Messelektronik werden präsentiert. Darüber hinaus werden ausgewählte Ergebnisse von Strömungsvisualisierungen dargestellt und diskutiert.
Quantifizierung von Flussgeschwindigkeiten mit dem Verfahren der Fourier Domain Optische KohärenztomografieFlow Velocity Quantification with Fourier Domain Optical Coherence Tomography
Authors: Walther Julia , Müller Gregor , Morawietz Henning , Koch Edmund
Published: June 2009

In dieser Studie werden zwei Methoden der Flussmessung, basierend auf dem Verfahren der Fourier Domain Optische Kohärenztomografie (FD OCT) vorgestellt. Das erste Verfahren beruht auf der Analyse der Phasenverschiebung zwischen konsekutiven Tiefensignalen durch axial bewegte Strukturen. Mit der zweiten Methode besteht die Möglichkeit höhere Geschwindigkeiten über den Signalabfall, hervorgerufen durch schnell bewegte Streuzentren, zu bestimmen.
Educational Perspectives
Authors: Gilhooly Joseph , Gilhooly Jennifer
Published: June 2009

Currently, four generations are actively working in today's health-care environment. Differences between these generations are creating conflicts and negatively affecting communication, productivity, and the satisfaction of all ages. Each of the generations has different values. Being aware and respecting these values is the first step in improving the academic and work environment. Practical solutions that address the generational preferences then can be developed.
Promoção da saúde no contexto paroara: possibilidade de cuidado de enfermagem
Authors: Cunha Regina Ribeiro , Pereira Luciléia da Silva , Gonçalves Ana Sofia Resque , Santos Evanguelia Kotzias Atherino dos , Radünz Vera , Heidemann Ivonete Teresinha Schülter Buss
Published: June 2009

O cuidado é considerado um bem social imensurável cujo significado está atrelado à vida e constitui uma das ações que visa a manutenção e promoção da saúde. O enfermeiro, como profissional ativo e transformador do ambiente social, tem o cuidado como elemento essencial de sua práxis. Esta reflexão tem como objetivo discutir uma das estratégias de promoção da saúde, o desenvolvimento de habilidades/atitudes pessoais, como possibilidade de cuidado de enfermagem para a melhoria da saúde dos paroaras. Pontua aspectos contextuais do cuidado, com ênfase na educação. Parte do princípio das atitudes pessoais da promoção, apontando desafios antropológicos no contexto sociocultural da Amazônia. Evidencia a necessidade de desenvolver habilidades pessoais como uma das estratégias que pode contribuir para o cuidado individual e coletivo, e o princípio do reforço da ação comunitária, essencial para o cuidado de enfermagem dos paroaras.