bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of an enzyme-linked immunosorbent assay for the detection of human calretinin in plasma and serum of mesothelioma patients
Authors: Raiko Irina , Sander Ingrid , Weber Daniel G , Raulf-Heimsoth Monika , Gillissen Adrian , Kollmeier Jens , Scherpereel Arnaud , Brüning Thomas , Johnen Georg
Published: May 2010

Background

Calretinin is one of the well-established immunohistochemical markers in the diagnostics of malignant mesothelioma (MM). Its utility as a diagnostic tool in human blood, however, is scarcely investigated. The aim of this study was to develop an enzyme-linked immunosorbent assay (ELISA) for human calretinin in blood and to assess its usefulness as a potential minimally invasive diagnostic marker for MM.

Methods

Initially, attempts were made to establish an assay using commercially available antibodies and to optimize it by including a biotin-streptavidin complex into the assay protocol. Subsequently, a novel ELISA based on polyclonal antibodies raised in rabbit immunized with human recombinant calretinin was developed. The assay performance in human serum and plasma (EDTA/heparin) and the influence of calcium concentrations on antibody recognition were studied. Stability of spiked-in calretinin in EDTA plasma under different storage conditions was also examined. In preliminary studies serum and plasma samples from 97 healthy volunteers, 35 asbestos-exposed workers, and 42 MM patients were analyzed.

Results

The mean detection range of the new ELISA was 0.12 to 8.97 ng/ml calretinin. The assay demonstrated markedly lower background and significantly higher sensitivity compared to the initially contrived assay that used commercial antibodies. Recovery rate experiments confirmed dependence of calretinin antibody recognition on calcium concentration. Calcium adjustment is necessary for calretinin measurement in EDTA plasma. Spiked-in calretinin revealed high stability in EDTA plasma when stored at room temperature, 4°C, or after repeated freeze/thaw cycles. Median calretinin values in healthy volunteers, asbestos workers, and MM patients were 0.20, 0.33, and 0.84 ng/ml, respectively (p < 0.0001 for healthy vs. MM, p = 0.0036 for healthy vs. asbestos-exposed, p < 0.0001 for asbestos-exposed vs. MM). Median values in patients with epithelioid and biphasic MM were similar. No influence of age, gender, smoking status, or type of medium (plasma/serum) on calretinin values was found.

Conclusions

The novel assay is highly sensitive and applicable to human serum and plasma. Calretinin appears to be a promising marker for the blood-based detection of MM and might complement other markers. However, further studies are required to prove its usefulness in the diagnosis of MM patients.
The Study of Environment on Aboriginal Resilience and Child Health (SEARCH): study protocol
Authors:   The SEARCH Investigators
Published: May 2010

Background

Aboriginal Australians have a life expectancy more than ten years less than that of non-Aboriginal Australians, reflecting their disproportionate burden of both communicable and non-communicable disease throughout the lifespan. Little is known about the health and health trajectories of Aboriginal children and, although the majority of Aboriginal people live in urban areas, data are particularly sparse in relation to children living in urban areas.

Methods/Design

The Study of Environment on Aboriginal Resilience and Child Health (SEARCH) is a cohort study of Aboriginal children aged 0-17 years, from urban and large regional centers in New South Wales, Australia. SEARCH focuses on Aboriginal community identified health priorities of: injury; otitis media; vaccine-preventable conditions; mental health problems; developmental delay; obesity; and risk factors for chronic disease. Parents/caregivers and their children are invited to participate in SEARCH at the time of presentation to one of the four participating Aboriginal Community Controlled Health Organisations at Mount Druitt, Campbelltown, Wagga Wagga and Newcastle. Questionnaire data are obtained from parents/caregivers and children, along with signed permission for follow-up through repeat data collection and data linkage. All children have their height, weight, waist circumference and blood pressure measured and complete audiometry, otoscopy/pneumatic otoscopy and tympanometry. Children aged 1-7 years have speech and language assessed and their parents/caregivers complete the Parental Evaluation of Developmental Status. The Study aims to recruit 1700 children by the end of 2010 and to secure resources for long term follow up. From November 2008 to March 2010, 1010 children had joined the study. From those 446 children with complete data entry, participating children ranged in age from 2 weeks to 17 years old, with 144 aged 0-3, 147 aged 4-7, 75 aged 8-10 and 79 aged 11-17. 55% were male and 45% female.

Discussion

SEARCH is built on strong community partnerships, under Aboriginal leadership, and addresses community priorities relating to a number of under-researched areas. SEARCH will provide a unique long-term resource to investigate the causes and trajectories of health and illness in urban Aboriginal children and to identify potential targets for interventions to improve health.
Novel structural features in two ZHX homeodomains derived from a systematic study of single and multiple domains
Authors: Bird Louise E , Ren Jingshan , Nettleship Joanne E , Folkers Gert E , Owens Raymond J , Stammers David K
Published: May 2010

Background

Zhx 1 to 3 (zinc-fingers and homeoboxes) form a set of paralogous genes encoding multi-domain proteins. ZHX proteins consist of two zinc fingers followed by five homeodomains. ZHXs have biological roles in cell cycle control by acting as co-repressors of the transcriptional regulator Nuclear Factor Y. As part of a structural genomics project we have expressed single and multi-domain fragments of the different human ZHX genes for use in structure determination.

Results

A total of 30 single and multiple domain ZHX1-3 constructs selected from bioinformatics protocols were screened for soluble expression in E. coli using high throughput methodologies. Two homeodomains were crystallized leading to structures for ZHX1 HD4 and ZHX2 HD2. ZHX1 HD4, although closest matched to homeodomains from 'homez' and 'engrailed', showed structural differences, notably an additional C-terminal helix (helix V) which wrapped over helix I thereby making extensive contacts. Although ZHX2 HD2-3 was successfully expressed and purified, proteolysis occurred during crystallization yielding crystals of just HD2. The structure of ZHX2 HD2 showed an unusual open conformation with helix I undergoing 'domain-swapping' to form a homodimer.

Conclusions

Although multiple-domain constructs of ZHX1 selected by bioinformatics studies could be expressed solubly, only single homeodomains yielded crystals. The crystal structure of ZHX1 HD4 showed additional hydrophobic interactions relative to many known homeodomains via extensive contacts formed by the novel C-terminal helix V with, in particular, helix I. Additionally, the replacement of some charged covariant residues (which are commonly observed to form salt bridges in non-homeotherms such as the Drosophila 'engrailed' homeodomain), by apolar residues further increases hydrophobic contacts within ZHX1 HD4, and potentially stability, relative to engrailed homeodomain. ZHX1 HD4 helix V points away from the normally observed DNA major groove binding site on homeodomains and thus would not obstruct the putative binding of nucleic acid. In contrast, for ZHX2 HD2 the observed altered conformation involving rearrangement of helix I, relative to the canonical homeodomain fold, disrupts the normal DNA binding site, although protein-protein binding is possible as observed in homodimer formation.
Study of bone remodeling of two models of femoral cementless stems by means of DEXA and finite elements
Authors: Gracia Luis , Ibarz Elena , Puértolas Sergio , Cegoñino José , López-Prats Fernando , Panisello Juan J , Herrera Antonio
Published: May 2010

Background

A hip replacement with a cemented or cementless femoral stem produces an effect on the bone called adaptive remodelling, attributable to mechanical and biological factors. All of the cementless prostheses designs try to achieve an optimal load transfer in order to avoid stress-shielding, which produces an osteopenia.

Long-term densitometric studies taken after implanting ABG-I and ABG-II stems confirm that the changes made to the design and alloy of the ABG-II stem help produce less proximal atrophy of the femur. The simulation with FE allowed us to study the biomechanical behaviour of two stems. The aim of this study was, if possible, to correlate the biological and mechanical findings.

Methods

Both models with prostheses ABG-I and II have been simulated in five different moments of time which coincide with the DEXA measurements: postoperative, 6 months, 1, 3 and 5 years, in addition to the healthy femur as the initial reference. For the complete comparative analysis of both stems, all of the possible combinations of bone mass (group I and group II of pacients in two controlled studies for ABG-I and II stems, respectively), prosthetic geometry (ABG-I and ABG-II) and stem material (Wrought Titanium or TMZF) were simulated.

Results and Discussion

In both groups of bone mass an increase of stress in the area of the cancellous bone is produced, which coincides with the end of the HA coating, as a consequence of the bottleneck effect which is produced in the transmission of loads, and corresponds to Gruen zones 2 and 6, where no osteopenia can be seen in contrast to zones 1 and 7.

Conclusions

In this study it is shown that the ABG-II stem is more effective than the ABG-I given that it generates higher tensional values on the bone, due to which proximal bone atrophy diminishes. This biomechanical behaviour with an improved transmission of loads confirmed by means of FE simulation corresponds to the biological findings obtained with Dual-Energy X-Ray Absorptiometry (DEXA).
Optical tomographic imaging discriminates between disease-modifying anti-rheumatic drug (DMARD) and non-DMARD efficacy in collagen antibody-induced arthritis
Authors: Peterson Jeffrey D , LaBranche Timothy P , Vasquez Kristine O , Kossodo Sylvie , Melton Michele , Rader Randall , Listello John T , Abrams Mark A , Misko Thomas P
Published: May 2010

Introduction

Standard measurements used to assess murine models of rheumatoid arthritis, notably paw thickness and clinical score, do not align well with certain aspects of disease severity as assessed by histopathology. We tested the hypothesis that non-invasive optical tomographic imaging of molecular biomarkers of inflammation and bone turnover would provide a superior quantitative readout and would discriminate between a disease-modifying anti-rheumatic drug (DMARD) and a non-DMARD treatment.

Methods

Using two protease-activated near-infrared fluorescence imaging agents to detect inflammation-associated cathepsin and matrix metalloprotease activity, and a third agent to detect bone turnover, we quantified fluorescence in paws of mice with collagen antibody-induced arthritis. Fluorescence molecular tomographic (FMT) imaging results, which provided deep tissue detection and quantitative readouts in absolute picomoles of agent fluorescence per paw, were compared with paw swelling, clinical scores, a panel of plasma biomarkers, and histopathology to discriminate between steroid (prednisolone), DMARD (p38 mitogen-activated protein kinase (MAPK) inhibitor) and non-DMARD (celecoxib, cyclooxygenase-2 (COX-2) inhibitor) treatments.

Results

Paw thickness, clinical score, and plasma biomarkers failed to discriminate well between a p38 MAPK inhibitor and a COX-2 inhibitor. In contrast, FMT quantification using near-infrared agents to detect protease activity or bone resorption yielded a clear discrimination between the different classes of therapeutics. FMT results agreed well with inflammation scores, and both imaging and histopathology provided clearer discrimination between treatments as compared with paw swelling, clinical score, and serum biomarker readouts.

Conclusions

Non-invasive optical tomographic imaging offers a unique approach to monitoring disease pathogenesis and correlates with histopathology assessment of joint inflammation and bone resorption. The specific use of optical tomography allowed accurate three-dimensional imaging, quantitation in picomoles rather than intensity or relative fluorescence, and, for the first time, showed that non-invasive imaging assessment can predict the pathologist's histology inflammation scoring and discriminate DMARD from non-DMARD activity.
Where Is This Place? Crowds, Audio-vision, and Poetry in Postelection Iran
Authors: Manoukian Setrag
Published: May 2010

Through a discussion of crowds and audio-vision in post-election Iran, the essay places the relationship between experience and politics at the center of current events in the country and analyzes the powerful but dispersed combination of crowds, images, sounds, voices, bodies and affects that are articulating it.
Excursion sets of three classes of stable random fields
Authors: Adler Robert J. , Samorodnitsky Gennady , Taylor Jonathan E.
Published: May 2010

Studying the geometry generated by Gaussian and Gaussian-related random fields via their excursion sets is now a well-developed and well-understood subject. The purely non-Gaussian scenario has, however, not been studied at all. In this paper we look at three classes of stable random fields, and obtain asymptotic formulae for the mean values of various geometric characteristics of their excursion sets over high levels. While the formulae are asymptotic, they contain enough information to show that not only do stable random fields exhibit geometric behaviour very different from that of Gaussian fields, but they also differ significantly among themselves.
Thinning spatial point processes into Poisson processes
Authors: Møller Jesper , Schoenberg Frederic Paik
Published: May 2010

In this paper we describe methods for randomly thinning certain classes of spatial point processes. In the case of a Markov point process, the proposed method involves a dependent thinning of a spatial birth-and-death process, where clans of ancestors associated with the original points are identified, and where we simulate backwards and forwards in order to obtain the thinned process. In the case of a Cox process, a simple independent thinning technique is proposed. In both cases, the thinning results in a Poisson process if and only if the true Papangelou conditional intensity is used, and, thus, can be used as a graphical exploratory tool for inspecting the goodness-of-fit of a spatial point process model. Several examples, including clustered and inhibitive point processes, are considered.
Stochastic ordering of classical discrete distributions
Authors: Klenke Achim , Mattner Lutz
Published: May 2010

For several pairs (P,Q) of classical distributions on ℕ0, we show that their stochastic orderingP≤stQcan be characterized by their extreme tail ordering equivalent toP({k*})/Q({k*}) ≥ 1 ≥ limk→k*P({k})/Q({k}), withk*andk*denoting the minimum and the supremum of the support ofP+Q, and with the limit to be read asP({k*})/Q({k*}) for finitek*. This includes in particular all pairs wherePandQare both binomial (bn1,p1≤stbn2,p2if and only ifn1≤n2and (1 -p1)n1≥ (1 -p2)n2, orp1= 0), both negative binomial (b−r1,p1≤stb−r2,p2if and only ifp1≥p2andp1r1≥p2r2), or both hypergeometric with the same sample size parameter. The binomial case is contained in a known result about Bernoulli convolutions, the other two cases appear to be new. The emphasis of this paper is on providing a variety of different methods of proofs: (i) half monotone likelihood ratios, (ii) explicit coupling, (iii) Markov chain comparison, (iv) analytic calculation, and (v) comparison of Lévy measures. We give four proofs in the binomial case (methods (i)-(iv)) and three in the negative binomial case (methods (i), (iv), and (v)). The statement for hypergeometric distributions is proved via method (i).
Critical markov branching process limit theorems allowing infinite variance
Authors: Pakes Anthony G.
Published: May 2010

This paper gives easy proofs of conditional limit laws for the population size Zt of a critical Markov branching process whose offspring law is attracted to a stable law with index 1 + α, where 0 ≤ α ≤ 1. Conditioning events subsume the usual ones, and more general initial laws are considered. The case α = 0 is related to extreme value theory for the Gumbel law.
Slope distribution in front-back asymmetric stochastic Lagrange time waves
Authors: Lindgren G.
Published: May 2010

The stochastic Lagrange wave model is a realistic alternative to the Gaussian linear wave model, which has been successfully used in ocean engineering for more than half a century. In this paper we present the slope distributions and other characteristic distributions at level crossings for asymmetric Lagrange time waves, i.e. what can be observed at a fixed measuring station, thereby extending results previously given for space waves. The distributions are given as expectations in a multivariate normal distribution, and they have to be evaluated by simulation or numerical integration. Interesting characteristic variables are the slope in time, the slope in space, and the vertical particle velocity when the waves are observed close to instances when the water level crosses a predetermined level. The theory has been made possible by recent generalizations of Rice's formula for the expected number of marked crossings in random fields.
Scaling limits for simple random walks on random ordered graph trees
Authors: Croydon D. A.
Published: May 2010

Consider a family of random ordered graph trees (Tn)n≥1, where Tn has n vertices. It has previously been established that if the associated search-depth processes converge to the normalised Brownian excursion when rescaled appropriately as n → ∞, then the simple random walks on the graph trees have the Brownian motion on the Brownian continuum random tree as their scaling limit. Here, this result is extended to demonstrate the existence of a diffusion scaling limit whenever the volume measure on the limiting real tree is nonatomic, supported on the leaves of the limiting tree, and satisfies a polynomial lower bound for the volume of balls. Furthermore, as an application of this generalisation, it is established that the simple random walks on a family of Galton-Watson trees with a critical infinite variance offspring distribution, conditioned on the total number of offspring, can be rescaled to converge to the Brownian motion on a related α-stable tree.
Low degree connectivity of ad-hoc networks via percolation
Authors: De Santis Emilio , Grandoni Fabrizio , Panconesi Alessandro
Published: May 2010

Consider the following classical problem in ad-hoc networks. Suppose that n devices are distributed uniformly at random in a given region. Each device is allowed to choose its own transmission radius, and two devices can communicate if and only if they are within the transmission radius of each other. The aim is to (quickly) establish a connected network of low average and maximum degree. In this paper we present the first efficient distributed protocols that, in poly-logarithmically many rounds and with high probability, set up a connected network with O(1) average degree and O(log n) maximum degree. Our algorithms are based on the following result, which is a nontrivial consequence of classical percolation theory. Suppose that each device sets up its transmission radius in order to reach the K closest devices. There exists a universal constant K (independent of n) such that, with high probability, there will be a unique giant component (i.e. a connected component of size Θ(n)). Furthermore, all remaining components will be of size O(log2n). This leads to an efficient distributed probabilistic test for membership in the giant component, which can be used in a second phase to achieve full connectivity.
Lizards respond to an extremely low-frequency electromagnetic field
Authors: Nishimura Tsutomu , Okano Hideyuki , Tada Harue , Nishimura Etsuko , Sugimoto Kenji , Mohri Kaneo , Fukushima Masanori
Published: May 2010

Animals from a wide range of taxa have been shown to possess magnetic sense and use magnetic compasses to orient; however, there is no information in the literature on whether lizards have either of these abilities. In this study, we investigated the behavioral responses of a diurnal agamid lizard (Pogona vitticeps) to a sinusoidal extremely low-frequency electromagnetic field (ELF-EMF; 6 and 8 Hz, peak magnetic field 2.6 μT, peak electric field 10 V m−1). Fourteen adult lizards were divided randomly into two groups (the EMF and control groups; each group had three males and four females). The EMF group received whole-body exposure to ELF-EMF and the control group did not. Lizards in the EMF group were exposed to ELF-EMF for 12 h per day (during the light period). The number of tail lifts was monitored beginning 3 days before exposure and ending after 5 days of exposure. For each individual, the average number of tail lifts per day was calculated. The average number of tail lifts per individual per day was greater in the EMF group than in the control group (20.7±6.3 and 9.1±4.5 tail lifts, respectively, N=7 each, P=0.02). We confirmed the reproducibility of this response by a cross-over trial. These results suggest that at least some lizards are able to perceive ELF-EMFs. Furthermore, when the parietal eye of the lizards was covered with a small round aluminum ‘cap’ which could block light, the tail-lifting response to ELF-EMF disappeared. Our experiments suggest that (1) lizards perceive EMFs and (2) the parietal eye may be involved in light-dependent magnetoreceptive responses.
Carotenoid-based coloration, oxidative stress and corticosterone in common lizards
Authors: Cote J. , Meylan S. , Clobert J. , Voituron Y.
Published: May 2010

Environmental factors including stressors, health status and social context significantly affect carotenoid-based coloration. For instance, stressors may induce the diversion of carotenoids from pigmentation pathways, potentially explaining why stressed animals often exhibit reduced coloration. However, we recently showed that high blood corticosterone concentrations, which are part of the physiological stress response, are associated with increased redness of the belly in the common lizard (Lacerta vivipara). This result clearly contrasts with the findings of many studies of carotenoid-based coloration because corticosterone is believed to increase oxidative stress. Here, we examined whether these positive effects are influenced by differences in food availability. We tested the effect of high corticosterone levels on carotenoid-based coloration, antioxidant enzyme activity and oxidative damage in common lizards subject to low and high food availability. Food restriction abolished the carotenoid-based color enhancement when corticosterone concentrations in animals were high. We discuss how carotenoid-based color can honestly signal individual quality in this species and how the increased redness induced by corticosterone could be a terminal investment in an environment where long-term survival prospects are poor but not when immediate survival is endangered.
A sky polarization compass in lizards: the central role of the parietal eye
Authors: Beltrami G. , Bertolucci C. , Parretta A. , Petrucci F. , Foà A.
Published: May 2010

The present study first examined whether ruin lizards Podarcis sicula are able to orientate using the e-vector direction of polarized light. Ruin lizards were trained and tested indoors, inside a hexagonal Morris water maze, positioned under an artificial light source producing plane polarized light with a single e-vector, which provided an axial cue. Lizards were subjected to axial training by positioning two identical goals in contact with the centre of two opposite side walls of the Morris water maze. Goals were invisible because they were placed just beneath the water surface, and water was rendered opaque. The results showed that the directional choices of lizards meeting learning criteria were bimodally distributed along the training axis, and that after 90 deg rotation of the e-vector direction of polarized light the lizards directional choices rotated correspondingly, producing a bimodal distribution which was perpendicular to the training axis. The present results confirm in ruin lizards results previously obtained in other lizard species showing that these reptiles can use the e-vector direction of polarized light in the form of a sky polarization compass. The second step of the study aimed at answering the still open question of whether functioning of a sky polarization compass would be mediated by the lizard parietal eye. To test this, ruin lizards meeting learning criteria were tested inside the Morris water maze under polarized light after their parietal eyes were painted black. Lizards with black-painted parietal eyes were completely disoriented. Thus, the present data show for the first time that the parietal eye plays a central role in mediating the functioning of a putative sky polarization compass of lizards.
Osmoregulation in the Antarctic nematodePanagrolaimus davidi
Authors: Wharton David A.
Published: May 2010

A technique for determining the internal osmotic concentration of a small nematode using a modified nanolitre osmometer is described and used to investigate osmoregulation in the Antarctic nematode Panagrolaimus davidi. This technique enables the osmotic concentration to the measured with an accuracy of ±12 mmol kg−1. The pattern of melting in the nematode's different body compartments suggests that it is the osmolality of its pseudocoelomic fluid that is being measured. Panagrolaimus davidi maintains its internal osmotic concentration above that of the external medium and is thus an hyperosmotic regulator. The nematode achieves regulation under hyposmotic stress more rapidly than under hyperosmotic stress.
Methamphetamine enhances memory of operantly conditioned respiratory behavior in the snailLymnaea stagnalis
Authors: Kennedy Colin D. , Houmes Stephen W. , Wyrick Katherine L. , Kammerzell Samuel M. , Lukowiak Ken , Sorg Barbara A.
Published: May 2010

Amphetamines have been used as cognitive enhancers to promote learning and memory. Amphetamines are also drugs of abuse that may promote the initiation of strong memories that ultimately lead to addiction. To understand how methamphetamine (Meth) may be augmenting learning and memory, we chose a relatively simple system, the pond snail, Lymnaea stagnalis. We studied the effects of Meth exposure on the long-term memory (LTM), extinction and reinstatement of operantly conditioned aerial respiratory behavior in Lymnaea. We first determined doses of Meth that would acutely alter respiratory behavior. Next, we measured the impact of training snails in Meth solution or water (control group) using a training procedure that produces LTM (>6 h) in control conditions. Meth exposure impaired the expression of LTM 21 h after two training sessions, but this appeared to be a context-dependent effect only. However, snails exposed to 3.3 μmol l−1 Meth during training had a decreased rate of extinction of the operantly conditioned memory. We then tested whether this decreased ability of snails to extinguish memory was due to enhanced LTM or impaired extinction of that memory. Snails were operantly conditioned in water and exposed to Meth 16 h after their last trial but 4–5 h prior to extinction. Meth produced an increase rather than a decrease in extinction rate. Thus, Meth impaired extinction only when snails were exposed to Meth during training. Last, we tested the effect of Meth on the ability to form LTM using a single training procedure that is suboptimal for LTM formation. Control snails did not demonstrate LTM, as expected, but pre-exposure of snails to 3.3 μmol l−1 Meth 24 h prior to the single training session produced LTM 24 h later, indicating that Meth pre-exposure primed snails for LTM formation. Taken together, our studies suggest that LTM is strengthened by Meth such that extinction training is less effective. Lymnaea provides a simple and useful model system to dissect the cellular and/or molecular mechanisms of how Meth may initiate the formation of stronger memories.
Effect of anomalous pulse timing on call discrimination by females of the gray treefrog (Hyla versicolor): behavioral correlates of neurobiology
Authors: Schwartz Joshua J. , Huth Kenneth , Hunce Raymond , Lentine Brandon
Published: May 2010

Research has demonstrated that certain midbrain neurons of anurans ‘count’ interpulse intervals (IPIs). Some neurons fire after exposure to fewer intervals than do others. Counting can be reset to zero if an IPI falls outside the cell's tolerance range. We tested female gray treefrogs for behavioral correlates of these neural response patterns using phonotaxis tests in order to gain a better understanding of the mechanistic bases of female responses to calls. For example, previous work demonstrated females often prefer longer to shorter pulsed advertisement calls, even when the former occur at lower rates. Call attractiveness can also be reduced when pulse duration and timing have been manipulated experimentally or disrupted by acoustic interference. In this study, female responses were consistent with neural data, emphasizing the importance of IPIs. Females discriminated in favor of calls with normal interpulse timing relative to those in which a single IPI was too long or too short. Our data suggest that neural resetting of interval counting by inappropriate intervals may more strongly influence females than reduced firing in response to such intervals on an individual basis. Data also suggest a transition point between 125 ms and 175 ms at which an interval between pulse strings is treated as an interval between calls.
Compound stiffness modelling of an integrated open-die forging centre with serial–parallel heavy-duty manipulators
Authors: Yan C , Gao F , Ge Q J
Published: May 2010

This paper presents a method for modelling the compound stiffness of an integrated open-die forging centre that consists of a forging press as well as a manipulator that handles the workpiece. Open-die forging has considerable differences to general machining processes due to the complex plastic deformation effects created by consecutive forging strikes. The manipulator must comply with the movement of the workpiece during forging. The stiffness of the integrated system mainly comes from two sources: the compliance of the manipulator and the elastic deformation of the workpiece during forging. First, the stiffness matrix of the workpiece is derived using the theory of mechanics of materials. Then, the complete Cartesian stiffness matrix of the manipulator is developed by using the conservative congruence transformation method. Finally, the compound stiffness model is constructed by combining these two stiffness matrices. A numerical algorithm is developed that is able to simulate the compliance motion of a programmed open-die forging process. Two numerical examples are presented to validate the proposed modelling method and numerical algorithm.
New mathematical approach for automatic piloting in computer aided progressive die design
Authors: Ghatrehnaby M , Arezoo B
Published: May 2010

Nowadays, progressive dies have a special role in various methods of sheet metal production. The design process, however, requires a considerable amount of time and expertise. During the last three decades, different concepts of computer aided progressive die design (CAPDD) have been studied all around the world. CAPDD includes various activities and among them piloting has been paid the least attention by researchers. In this paper, a mathematical model, based on the medial axis transform is introduced. This model analyses the part geometry in order to determine the piloting system. The model optimizes the piloting system using a minimum scrap strategy and other technical considerations. A program is also developed to automatically select the most suitable existing holes or design auxiliary holes on the scrap part of the strip for piloting purposes. The input to the program is the nesting template of the workpiece, which is composed of line and arc segments, and the output is the piloting system. The model is demonstrated through several industrial examples.
Two-dimensional vibration-assisted micro end milling: Cutting force modelling and machining process dynamics
Authors: Ding H , Chen S-J , Cheng K
Published: May 2010

A three-dimensional (3D) cutting force model of two-dimensional (2D) vibration-assisted micro end milling (2D VAMEM) is presented in this paper. The model calculates the chip thickness by considering the relative trajectory of the tool tip to the workpiece while the tool rotates and the workpiece moves ahead continuously and vibrates in the feed and normal directions. In addition, a cutting process dynamics model of 2D VAMEM is established, which is combined with the cutting force model. The estimated cutting forces using the proposed models with and without considering dynamics both have a reasonable agreement with the experimental while considering dynamics leads to close agreement with the experimental data. The effects of amplitude on the maximum cutting force level and average cutting force are also studied. The two proposed models can be used to study the various characteristics of 2D VAMEM, including dynamic stability, positioning accuracy, surface texture generation, and tool wear.
Failure risk in powder-compacted parts
Authors: Rolland S A , Gethin D T , Lewis R W , Tweed J H
Published: May 2010

This article addresses the occurrence of crack-related failure within the powder compaction cycle. Both tensile and shear cracks are considered together with the challenges associated with their detection. Experimental data are presented from the compaction of multi-level parts pressed from DistaloyAE powder to green densities between 6 and 7 g/cm3. This is compared with process simulation results. Both point to compact fragility and that failure is reflected in a dilation mechanism. This is contrary to expectation where a shear-type failure was expected. Simulation of the compaction and ejection of a plain cylinder were also undertaken. This highlighted the impact of punch hold down and how it may be used to achieve part integrity through control of stress excursion within the compact. The final part of the article describes, for the first time, the integration of a failure risk model within compaction simulation. As a proof of concept, this was demonstrated to highlight high-risk areas for failure within the compaction cycle.
The influence of the geometry of the leading edge of diffuser vanes on the noise generated by a centrifugal fan
Authors: Zhang W , Gong W , Xi G
Published: May 2010

An experimental study is described to investigate the influence of diffuser vane leading edge on the noise behaviour of a centrifugal fan. The geometric shapes of the diffuser vane leading edge refer to the diffuser inlet radius, and the broken and inclined leading edges. The sound pressure level and pressure rise of the centrifugal fan were measured in a semianechoic chamber. The rotational speed of the test fan varied from 20 000 to 35 000 r/min; the flow coefficient was in the range of 0.02–0.14. The results show that: (a) by using the inclined leading edge vaned diffuser (ILEVD) with proper inclined angle, the overall fan noise is reduced by 3.6 dB(A), and the fan performance is improved; (b) when the diffuser leading edge radius R3/ R2 increases from 1.03 to 1.07, the tones are reduced whereas the broadband noise is almost unchanged; and (c) the influence of the broken leading edge diffuser on the overall fan noise and performance is negligible, although the tonal noise is reduced by 4 dB(A). In order to better understand the behaviour of the ILEVDs, a numerical simulation has been carried out on steady three-dimensional flows. The results indicate that the flow condition improves by the application of the ILEVD.
Experimental analysis of reciprocating compressor performance with eco-friendly refrigerants
Authors: Bolaji B O
Published: May 2010

This article evaluates the compressor performance using five eco-friendly refrigerants in comparison to R12. Experimental apparatus of a complete refrigeration system with reciprocating compressor was developed and the performance of the system with selected refrigerants was evaluated. The results obtained showed that only R134a and R152a have their coefficients of performances close to that of R12 with 6.6 per cent and 3.1 per cent reductions, respectively. Comparison between refrigeration capacities showed the superiority of R152a with 4.9 per cent higher than that of R12. The volumetric efficiencies obtained were 75.8 per cent, 74.4 per cent, and 77.9 per cent for R12, R134a, and R152a, respectively, whereas those of R23, R32, and R143a were 56.8 per cent, 60.6 per cent, and 69.7 per cent respectively. Therefore, R134a and R152a will perform well as substitutes for R12 in vapour compression refrigeration system.
Backstepping Sliding-Mode Control for a Pneumatic Control System
Authors: Lu C-H , Hwang Y-R , Shen Y-T
Published: May 2010

In general, air motors have been applied for automation in industry. There are many kinds of air motors used in automation equipment, such as vane air motors, piston air motors, etc. The advantage of the piston air motor is that it is able to provide larger torque at low speed than air vane motors. The aim of the present study was to analyse the behaviour of such a motor, a radial piston air motor mounted on a ball screw table, and to accomplish accurate desired positioning utilizing a backstepping sliding-mode controller. Variation due to compressibility of the air and friction in the mechanism make the overall system non-linear. Two methods were applied to overcome the chattering phenomenon and control the system: the proportional—integral—derivative controller and the backstepping sliding-mode controller. Experimental results showed that the proposed backstepping sliding-mode controller apparently suppresses overshoot and provides accurate positioning performance.
Synthesis and Properties of 2,2′-Di(heteroaryl)-9,9′-spirobifluorenes
Authors: Jahng Yurngdong , Rahman A F M Motiur
Published: May 2010

A series of 2,2′-di(heteroaryl)-9,9′-spirobifluorenes were prepared by employing Friedländer reaction of 2,2′-diacetyl-9,9′-spirodifluorene with a series of ortho-aminoarenecarbaldehydes. The compound 2,2′-di(benzo[b]-1,10-phenanthrolin-2-yl)-9,9′-spirofluorene (4e) showed a green light emission at 500 nm upon the excitation of the absorption at 374 nm while 2,2′-di(benzo[h]quinolin-2-yl)-9,9′-spirofluorene (4c), 2,2′-di(1,10-phenanthrolin-2-yl)-9,9′-spirofluorene (4d), 2-(benzo[h]quinolin-2-yl)-2′-(benzo[b]-1,10-phenanthrolin-2-yl)-9,9′-spirofluorene (4g), and 2-(1,10-phenanthrolin-2-yl)-2′-(benzo[b]-1,10-phenanthrolin-2-yl)-9,9′-spirofluorene (4h) showed emissions at 413, 465, 442, and 442 nm upon excitation of the absorption at 370, 362, 370, and 363 nm, respectively, thus having potential for OLED applications.
Role of Substrate Reactivity in the Glutathione Peroxidase (GPx) Activity of Selenocystine
Authors: Singh Beena G , Bag Partha P , Kumakura Fumio , Iwaoka Michio , Priyadarsini K Indira
Published: May 2010

Selenocystine (CysSeSeCys), a diselenide, exhibits glutathione peroxidase (GPx) activity, where it catalyses the reduction of hydroperoxides using a thiol co-factor. To understand the relative reactivity of the two substrates, enzyme kinetic parameters, i.e., the turnover number (kcat) and the relative reactivity parameters toward thiol (φG) and hydroperoxide (φH), were determined by applying Dalziel kinetics for a bi-substrate model in the presence of hydrogen peroxide (H2O2), t-butyl hydroperoxide, or α-cumyl hydroperoxide and glutathione or dithiothreitol (DTTred). The intermediates formed during the reaction of CysSeSeCys with H2O2 and DTTred were characterized by 77Se NMR spectroscopy. Ab initio calculation at HF/6-31G(d) indicated that the reactions with H2O2 are exothermic, while those with DTTred are endothermic. Based on these studies, the GPx activity of CysSeSeCys is likely to be initiated by the reaction with hydroperoxide and in the catalytic cycle, the reaction with thiol is the rate-determining step.
X-ray Crystallography of D149 Ethyl Ester
Authors: Matsui Masaki , Fujita Tomoki , Kubota Yasuhiro , Funabiki Kazumasa , Miura Hidetoshi , Shiro Motoo
Published: May 2010

D149 ethyl ester molecules are arranged in a “herringbone” fashion. Cyclopentane, phenylene, and one of the phenyl moieties surround a planar π-conjugated chromophore to weaken π–π stacking between the molecules arranged in parallel.
Reduction of Volume Shrinkage in Holographic Polymer Dispersed Liquid Crystal Based on Epoxy Containing Polymer Matrices
Authors: Woo Ju Yeon , Kang Young Soo , Kim Byung Kyu
Published: May 2010

The grating formation dynamics, SEM images, diffraction efficiency, and electrooptical properties of transmission grating of holographic polymer dispersed liquid crystals (HPDLCs) have been investigated by incorporating three different types of monofunctional reactive diluents into the host polymer matrices. A gradual increase of real time diffraction efficiency, a decrease of LC droplet size, and an increase of diffraction efficiency of the composite film were obtained with the addition of epoxy acrylate monomers due to the increased viscosity of polymer/LC mixtures leading to decreased droplet coalescence. In addition, epoxy acrylate monomers induced decreased volume shrinkage according to their ring structure with bulky group. Driving voltage increased with the addition of epoxy monomers whereas rise time and decay time decreased as a result of the decreased LC droplet size. At an optimum composition of epoxy monomer, a minimum switching voltage of 6 V µm−1 and rise time of 0.15 ms and a decay time of 18.05 ms were respectively obtained.
Differential effects of whole soy extract and soy isoflavones on apoptosis in prostate cancer cells
Authors: Hsu Anna , Bray Tammy M , Helferich William G , Doerge Daniel R , Ho Emily
Published: May 2010

Previous studies have suggested that soy isoflavones exert anticarcinogenic effects against prostate cancer. We propose that soy extracts, containing a mixture of soy isoflavones and other bioactive components, would be a more potent chemo-preventive agent than individual soy isoflavones. We compared the apoptotic effects of whole soy extracts and individual soy isoflavones, genistein and daidzein, on prostate cancer cells. The soy extract contained 50% w/w of total isoflavones with approximately 1:5.5:3.5 ratios of genistin, daidzin and glycitin, respectively. Benign prostate hyperplasia (BPH-1), LnCap and PC3 cells were treated with varying concentrations of soy extract, genistein or daidzein and analyzed for cell cycle alterations and induction of apoptosis. At equal concentrations (25 μmol/L), soy extract induced a significantly higher percentage of cells undergoing apoptosis than genistein or daidzein ( P < 0.001). No significant changes in cell cycle arrest or apoptosis were observed in non-cancerous BPH-1 cells treated with soy extract, suggesting that the effects of soy extract may be tumor cell specific. On the contrary, both genistein and daidzein induced apoptosis in BPH-1 cells, suggesting that individual isoflavones may have cytotoxicity in non-cancerous cells. Soy extracts also increased Bax expression in PC3 cells, but no significant changes in nuclear factor κB (NF κB) activation were detected, suggesting that the induction of apoptosis was independent of the NF κB pathway. Food products that bear a combination of active compounds may be more efficacious and safer as chemo-preventive agents than individual compounds. This ‘whole-food’-based approach is significant for the development of public health recommendations for prostate cancer prevention.
Oxidative alterations inducedin vitroby the photodynamic reaction in doxorubicin-sensitive (LoVo) and -resistant (LoVoDX) colon adenocarcinoma cells
Authors: Kulbacka Julita , Chwiłkowska Agnieszka , Bar Julia , Poła Andrzej , Banaś Teresa , Gamian Andrzej , Saczko Jolanta
Published: May 2010

In photodynamic therapy (PDT) a tumor-selective photosensitizer is administered and then activated by exposure to a light source of appropriate wavelength. Multidrug resistance (MDR) is largely caused by the drug efflux from the tumor cell by means of P-glycoprotein, resulting in reduced efficacy of the anticancer therapy. This study deals with photodynamic therapy with Photofrin®(Ph) on colon cancer cell lines (doxorubicin-sensitive and -resistant). The cells were treated with 15 and 30 μg/mL Ph and then irradiated by a light dose of 3 or 6 J/cm2(632.8 nm). After irradiation the cells were incubated for 0, 3 or 18 h. Crucial factors of oxidative stress (thiobarbituric acid reactive substances [TBARS], protein damage, thiazolyl blue tetrazolium bromide [MTT] assay), changes in cytosolic superoxide dismutase (SOD1) activity after photodynamic reaction (PDR), and the intracellular accumulation of photosensitizers in the cells were examined. Moreover, the expressions of glutathione S-transferase (GST)-pi, a marker protein for photochemical toxicity, and secretory phospholipase A2, a prognostic and diagnostic marker for colon cancers, were determined. After PDR, increases in SOD1 activity and the level of TBARS were observed in both cell lines. The level of protein-associated –SH groups decreased after PDR. Both cell lines demonstrated stronger GST-pi and PLA2expression after PDR, especially after 18 h of incubation. The increasing level of reactive oxygen species following the oxidation of sulfhydryl cell groups and lipid peroxidation influence the activity of many transporters and enzymes. The changes in SOD1 activity show that photodynamic action generates oxidative stress in treated cells. Our study presents that PDR caused oxidative alterations in both examined colon adenocarcinoma cell lines. However, the MDR cells reacted more slowly and all oxidative changes occurred in the delay.