bluuebunny/crossref_metadata_2025 huggingface dataset:
Ribosome Biogenesis and the Translation Process inEscherichia coli
Authors: Kaczanowska Magdalena , Rydén-Aulin Monica
Published: September 2007

Translation, the decoding of mRNA into protein, is the third and final element of the central dogma. The ribosome, a nucleoprotein particle, is responsible and essential for this process. The bacterial ribosome consists of three rRNA molecules and approximately 55 proteins, components that are put together in an intricate and tightly regulated way. When finally matured, the quality of the particle, as well as the amount of active ribosomes, must be checked. The focus of this review is ribosome biogenesis inEscherichia coliand its cross-talk with the ongoing protein synthesis. We discuss how the ribosomal components are produced and how their synthesis is regulated according to growth rate and the nutritional contents of the medium. We also present the many accessory factors important for the correct assembly process, the list of which has grown substantially during the last few years, even though the precise mechanisms and roles of most of the proteins are not understood.
CENTRALITY ESTIMATION IN LARGE NETWORKS
Authors: BRANDES ULRIK , PICH CHRISTIAN
Published: September 2007

Centrality indices are an essential concept in network analysis. For those based on shortest-path distances the computation is at least quadratic in the number of nodes, since it usually involves solving the single-source shortest-paths (SSSP) problem from every node. Therefore, exact computation is infeasible for many large networks of interest today. Centrality scores can be estimated, however, from a limited number of SSSP computations. We present results from an experimental study of the quality of such estimates under various selection strategies for the source vertices.
SPANNING TREES AND BOOTSTRAP RELIABILITY ESTIMATION IN CORRELATION-BASED NETWORKS
Authors: TUMMINELLO MICHELE , CORONNELLO CLAUDIA , LILLO FABRIZIO , MICCICHÈ SALVATORE , MANTEGNA ROSARIO N.
Published: September 2007

We introduce a new technique to associate a spanning tree to the average linkage cluster analysis. We term this tree as the Average Linkage Minimum Spanning Tree. We also introduce a technique to associate a value of reliability to the links of correlation-based graphs by using bootstrap replicas of data. Both techniques are applied to the portfolio of the 300 most capitalized stocks traded on the New York Stock Exchange during the time period 2001–2003. We show that the Average Linkage Minimum Spanning Tree recognizes economic sectors and sub-sectors as communities in the network slightly better than the Minimum Spanning Tree. We also show that the average reliability of links in the Minimum Spanning Tree is slightly greater than the average reliability of links in the Average Linkage Minimum Spanning Tree.
SOCIAL SEARCH ENGINES
Authors: MARCHIORI MASSIMO
Published: September 2007

The web landscape has undergone massive changes in the past years. On the other hand, search engine technology has not quite kept the same pace. In this article we look at the current scenarios, and argue how social flows can be used to make up for a better generation of search engines. We consider how society and technological progress somehow changed the rules of the game, introducing good but also bad components, and see how this situation could be modeled by search engines. Along this line of thinking, we show how the real components of interest are not just web pages, but flows of information of any kind, that need to be merged: this opens up for a wide range of improvements and far-looking developments, towards a new horizon of social search.
EFFECTS OF LONG-RANGE CONNECTIONS IN DISTRIBUTED CONTROL OF COLLECTIVE MOTION
Authors: BUSCARINO ARTURO , FORTUNA LUIGI , FRASCA MATTIA , RIZZO ALESSANDRO
Published: September 2007

The introduction of long-range connections in locally connected networks leads to the so-called small-world effect: when few long-range connections are added to the original topology, the characteristic path length decreases, whereas a high clustering coefficient is preserved. In this paper, it is shown that long-range connections introduced in a network model describing the interactions of a group of mobile robots increase the tendency to form a coordinated group of robots which travel in the same direction. The leadership of informed individuals in the group is also increased.
TOPOLOGICAL VULNERABILITY OF THE EUROPEAN POWER GRID UNDER ERRORS AND ATTACKS
Authors: ROSAS-CASALS MARTÍ , VALVERDE SERGI , SOLÉ RICARD V.
Published: September 2007

We present an analysis of the topological structure and static tolerance to errors and attacks of the September 2003 actualization of the Union for the Coordination of Transport of Electricity (UCTE) power grid, involving thirty-three different networks. Though every power grid studied has exponential degree distribution and most of them lack typical small-world topology, they display patterns of reaction to node loss similar to those observed in scale-free networks. We have found that the node removal behavior can be logarithmically related to the power grid size. This logarithmic behavior would suggest that, though size favors fragility, growth can reduce it. We conclude that, with the ever-growing demand for power and reliability, actual planning strategies to increase transmission systems would have to take into account this relative increase in vulnerability with size, in order to facilitate and improve the power grid design and functioning.
SYNCHRONIZATION OF NETWORKS WITH VARIABLE LOCAL PROPERTIES
Authors: GÓMEZ-GARDEÑES JESÚS , MORENO YAMIR
Published: September 2007

We study the synchronization transition of Kuramoto oscillators in scale-free networks that are characterized by tunable local properties. Specifically, we perform a detailed finite size scaling analysis and inspect how the critical properties of the dynamics change when the clustering coefficient and the average shortest path length are varied. The results show that the onset of synchronization does depend on these properties, though the dependence is smooth. On the contrary, the appearance of complete synchronization is radically affected by the structure of the networks. Our study highlights the need of exploring the whole phase diagram and not only the stability of the fully synchronized state, where most studies have been done up to now.
NETWORKS AND OUR LIMITED INFORMATION HORIZON
Authors: ROSVALL M. , SNEPPEN K.
Published: September 2007

In this paper we quantify our limited information horizon, by measuring the information necessary to locate specific nodes in a network. To investigate different ways to overcome this horizon, and the interplay between communication and topology in social networks, we let agents communicate in a model society. Thereby they build a perception of the network that they can use to create strategic links to improve their standing in the network. We observe a narrow distribution of links when the communication is low and a network with a broad distribution of links when the communication is high.
TWOFOLD IMPACT OF DELAYED FEEDBACK ON COUPLED OSCILLATORS
Authors: POPOVYCH OLEKSANDR V. , KRACHKOVSKYI VALERII , TASS PETER A.
Published: September 2007

We present a detailed bifurcation analysis of desynchronization transitions in a system of two coupled phase oscillators with delay. The coupling between the oscillators combines a delayed self-feedback of each oscillator with an instantaneous mutual interaction. The delayed self-feedback leads to a rich variety of dynamical regimes, ranging from phase-locked and periodically modulated synchronized states to chaotic phase synchronization and desynchronization. We show that an increase of the coupling strength between oscillators may lead to a loss of synchronization. Intriguingly, the delay has a twofold influence on the oscillations: synchronizing for small and intermediate coupling strength and desynchronizing if the coupling strength exceeds a certain threshold value. We show that the desynchronization transition has the form of a crisis bifurcation of a chaotic attractor of chaotic phase synchronization. This study contributes to a better understanding of the impact of time delay on interacting oscillators.
APPLYING A TAXONOMY OF FORMATION CONTROL IN DEVELOPING A ROBOTIC SYSTEM
Authors: HSU HARRY CHIA-HUNG , LIU ALAN
Published: September 2007

Designing cooperative multi-robot systems (MRS) requires expert knowledge both in control and artificial intelligence. Formation control is an important research within the research field of MRS. Since many researchers use different ways in approaching formation control, we try to give a taxonomy in order to help researchers design formation systems in a systematical way. We can analyze formation structures in two categories: control abstraction and robot distinguishability. The control abstraction can be divided into three layers: formation shape, reference type, and robotic control. Furthermore, robots can be classified as anonymous robots or identification robots depending on whether robots are distinguishable according to their inner states. We use this taxonomy to analyze some ground-based formation systems and to state current challenges of formation control. Such information becomes the design know-how in developing a formation system, and a case study of designing a multi-team formation system is introduced to demonstrate the usefulness of the taxonomy.
GROUND-GLASS OPACITY DETECTION BY USING CORRELATION BETWEEN SUCCESSIVE SLICE IMAGES
Authors: KIM HYOUNGSEOP , MAEKADO MASAKI , TAN JOO KOOI , ISHIKAWA SEIJI , TSUKUDA MASAAKI
Published: September 2007

Medical imaging systems such as computed tomography, magnetic resonance imaging provided a high resolution image for powerful diagnostic tool in visual inspection fields by physician. Especially MDCT image can be used to obtain detailed images of the pulmonary anatomy, including pulmonary diseases such as the pulmonary nodules, the pulmonary vein, etc. In the medical image processing technique, segmentation is a difficult task because surrounding soft tissues and organs have similar CT values and sometimes contact with each other. We propose a new technique for automatic segmentation of lung regions and its classification for ground-glass opacity from the extracted lung regions by computer based on a set of the thorax CT images. In this paper, we segment the lung region for extraction of the region of interest employing binarization and labeling process from the inputted each slices images. The region having the largest area is regarded as the tentative lung regions. Furthermore, the ground-glass opacity is classified by correlation distribution on the slice to slice from the extracted lung region with respect to the thorax CT images. Experiment is performed employing twenty six thorax CT image sets and 96% of recognition rates were achieved. Obtained results are shown along with a discussion.
NAVIGATION OF AN AUTONOMOUS SEWER INSPECTION ROBOT BASED ON STEREO CAMERA IMAGES AND LASER SCANNER DATA
Authors: AHRARY ALIREZA , TIAN LI , KAMATA SEI-ICHIRO , ISHIKAWA MASUMI
Published: September 2007

Sewer environment is composed of cylindrical pipes, in which only a few landmarks such as manholes, inlets and pipe joints are available for localization. This paper presents a method for navigation of an autonomous sewer inspection robot in a sewer pipe system based on detection of landmarks. In this method, location of an autonomous sewer inspection robot in the sewer pipe system is estimated from stereo camera images. The laser scanner data are also used to ensure accurate localization of the landmarks and reduce the error in distance estimation by image processing. The method is implemented and evaluated in a sewer pipe test field using a prototype robot, demonstrating its effectiveness.
ADAPTIVE SPAM FILTERING USING DYNAMIC FEATURE SPACES
Authors: ZHOU YAN , MULEKAR MADHURI S. , NERELLAPALLI PRAVEEN
Published: September 2007

Unsolicited bulk e-mail, also known as spam, has been an increasing problem for the e-mail society. This paper presents a new spam filtering strategy that 1) uses a practical entropy coding technique, Huffman coding, to dynamically encode the feature space of the e-mail collected over time and, 2) applies an online algorithm to adaptively enhance the learned spam concept as new e-mail data becomes available. The contributions of this work include a highly efficient spam filtering algorithm in which the input space is radically reduced to a single-dimension input vector, and an adaptive learning technique that is robust to vocabulary change, concept drifting and skewed class distributions. We compare our technique with several existing off-line learning techniques including support vector machine, logistic regression, naïve Bayes, k-nearest neighbor, C4.5 decision tree, RBFNetwork, boosted decision tree and stacking. We demonstrate the effectiveness of our technique by presenting the experimental results on the e-mail data that is publicly available. A more in-depth statistical analysis on the experimental results is also presented and discussed.
THE QUALITATIVE TREATMENT OF SPATIAL DATA
Authors: TAKAHASHI KAZUKO , SUMITOMO TAKAO
Published: September 2007

This paper aims at an efficient treatment of spatial data using qualitative representation. We propose a new framework called PLCA, which provides a symbolic representation for the figure in a two-dimensional plane, focusing on the connections between regions. It is based on four simple objects: points(P), lines(L), circuits(C) and areas(A). The entire figure is represented as a combination of these objects. Pairs of areas, circuits or lines never cross. The simple, clear data structure based on objects makes the system feasible and easy to implement. A PLCA expression can be subject to topological reasoning such as judging the connection patterns of areas.

We define the operations of area integration and area division on a PLCA expression. These operations preserve the consistency of the expression, and correspond to real actions on the figures.

We can add attributes to each object, such as the properties that hold on an area or that an object represents, and make an attributed PLCA. The operations of area integration/division on an attributed PLCA correspond to the alteration of the classification level of objects, and semantic spatial reasoning can be performed on an attributed PLCA.
BUILDING CONSISTENCIES FOR PARTIALLY DEFINED CONSTRAINTS WITH DECISION TREES AND NEURAL NETWORKS
Authors: LALLOUET ARNAUD , LEGTCHENKO ANDREI
Published: September 2007

Partially Defined Constraints can be used to model the incomplete knowledge of a concept or a relation. Instead of only computing with the known part of the constraint, we propose to complete its definition by using Machine Learning techniques. Since constraints are actively used during solving for pruning domains, building a classifier for instances is not enough: we need a solver able to reduce variable domains. Our technique is composed of two steps: first we learn a classifier for each constraint projections and then we transform the classifiers into a propagator. The first contribution is a generic meta-technique for classifier improvement showing performances comparable to boosting. The second lies in the ability of using the learned concept in constraint-based decision or optimization problems. We presents results using Decision Trees and Artificial Neural Networks for constraint learning and propagation. It opens a new way of integrating Machine Learning in Decision Support Systems.
Glucose infusion causes insulin resistance in skeletal muscle of rats without changes in Akt and AS160 phosphorylation
Authors: Hoy Andrew J. , Bruce Clinton R. , Cederberg Anna , Turner Nigel , James David E. , Cooney Gregory J. , Kraegen Edward W.
Published: September 2007

Hyperglycemia is a defining feature of Type 1 and 2 diabetes. Hyperglycemia also causes insulin resistance, and our group (Kraegen EW, Saha AK, Preston E, Wilks D, Hoy AJ, Cooney GJ, Ruderman NB. Am J Physiol Endocrinol Metab Endocrinol Metab 290: E471–E479, 2006) has recently demonstrated that hyperglycemia generated by glucose infusion results in insulin resistance after 5 h but not after 3 h. The aim of this study was to investigate possible mechanism(s) by which glucose infusion causes insulin resistance in skeletal muscle and in particular to examine whether this was associated with changes in insulin signaling. Hyperglycemia (∼10 mM) was produced in cannulated male Wistar rats for up to 5 h. The glucose infusion rate required to maintain this hyperglycemia progressively lessened over 5 h (by 25%, P < 0.0001 at 5 h) without any alteration in plasma insulin levels consistent with the development of insulin resistance. Muscle glucose uptake in vivo (44%; P < 0.05) and glycogen synthesis rate (52%; P < 0.001) were reduced after 5 h compared with after 3 h of infusion. Despite these changes, there was no decrease in the phosphorylation state of multiple insulin signaling intermediates [insulin receptor, Akt, AS160 (Akt substrate of 160 kDa), glycogen synthase kinase-3β] over the same time course. In isolated soleus strips taken from control or 1- or 5-h glucose-infused animals, insulin-stimulated 2-deoxyglucose transport was similar, but glycogen synthesis was significantly reduced in the 5-h muscle sample (68% vs. 1-h sample; P < 0.001). These results suggest that the reduced muscle glucose uptake in rats after 5 h of acute hyperglycemia is due more to the metabolic effects of excess glycogen storage than to a defect in insulin signaling or glucose transport.
Selective role of neuropeptide Y receptor subtype Y2in the control of gonadotropin secretion in the rat
Authors: Pinilla L. , Fernández-Fernández R. , Roa J. , Castellano J. M. , Tena-Sempere M. , Aguilar E.
Published: September 2007

Different signals with key roles in energy homeostasis regulate the reproductive axis. These include neuropeptide Y and polypeptide YY3-36, whose type Y2receptor is the most abundant of this family in the brain. We evaluated herein the putative roles of Y2receptors in the control of gonadotropin secretion by means of central administration of PYY13-36(agonist of Y2receptors) and BIIE 0246 (antagonist of Y2receptors) to intact and orchidectomized male rats. In addition, the ability of PYY13-36to elicit GnRH and gonadotropin secretion in vitro and the impact of fasting on LH responses to PYY13-36in vivo were also monitored. Central administration of PYY13-36significantly decreased the circulating levels of both gonadotropins, an effect that was observed in prepubertal and adult rats. Yet a dual action of Y2receptors in the control of male gonadotropic axis was evidenced as their activation induced 1) stimulation of gonadotropin responses to GnRH at the pituitary but 2) inhibition of GnRH secretion at the hypothalamus. Antagonization of Y2receptors failed to modify basal LH secretion in intact males either after being fed ad libitum or after being fasted. In contrast, their central blockade in orchidectomized rats evoked a significant increase in circulating LH and FSH level, suggesting the constitutive activation of Y2receptor in such stimulated conditions. In summary, our data evidence a complex mode of action of Y2receptors in the control of gonadotropic axis, with stimulatory and inhibitory actions at different levels of the system that are sensitive to the gonadal status.
The expression of prolactin and its cathepsin D-mediated cleavage in the bovine corpus luteum vary with the estrous cycle
Authors: Erdmann Sabine , Ricken Albert , Merkwitz Claudia , Struman Ingrid , Castino Roberta , Hummitzsch Katja , Gaunitz Frank , Isidoro Ciro , Martial Joseph , Spanel-Borowski Katharina
Published: September 2007

In the corpus luteum (CL), blood vessels develop, stabilize, and regress. This process depends on the ratio of pro- and antiangiogenic factors, which change during the ovarian cycle. The present study focuses on the possible roles of 23,000 (23K) prolactin (PRL) in the bovine CL and its antiangiogenic NH2-terminal fragments after extracellular cleavage by cathepsin D (Cath D). PRL RNA and protein were demonstrated in the CL tissue, in luteal endothelial cells, and in steroidogenic cells. Cath D was detected in CL tissue, cell extracts, and corresponding cell supernatants. In the intact CL, 23K PRL levels decreased gradually, whereas Cath D levels concomitantly increased between early and late luteal stages. In vitro, PRL cleavage occurred in the presence of acidified homogenates of CL tissue, cells, and corresponding cell supernatants. Similar fragments were obtained with purified Cath D, and their appearance was inhibited by pepstatin A. The aspartic protease specific substrate MOCAc-GKPILF∼FRLK(Dnp)-d- R-NH2was cleaved by CL cell supernatants, providing further evidence for Cath D activity. The 16,000 PRL inhibited proliferation of luteal endothelial cells accompanied by an increase in cleaved caspase-3. In conclusion, 1) the bovine CL is able to produce PRL and to process it into antiangiogenic fragments by Cath D activity and 2) PRL cleavage might mediate angioregression during luteolysis.
Characterization of hepatic and brain metabolism in young adults with glycogen storage disease type 1: a magnetic resonance spectroscopy study
Authors: Weghuber D. , Mandl M. , Krššák M. , Roden M. , Nowotny P. , Brehm A. , Krebs M. , Widhalm K. , Bischof M. G.
Published: September 2007

In glycogen storage disease type 1 (GSD1), children present with severe hypoglycemia, whereas the propensity for hypoglycemia may decrease with age in these patients. It was the aim of this study to elucidate the mechanisms for milder hypoglycemia symptoms in young adult GSD1 patients. Four patients with GSD1 [body mass index (BMI) 23.2 ± 6.3 kg/m, age 21.3 ± 2.9 yr] and four healthy controls matched for BMI (23.1 ± 3.0 kg/m) and age (24.0 ± 3.1 yr) were studied. Combined1H/31P nuclear magnetic resonance spectroscopy (NMRS) was used to assess brain metabolism. Before and after administration of 1 mg glucagon, endogenous glucose production (EGP) was measured with d-[6,6-2H2]glucose and hepatic glucose metabolism was examined by1H/13C/31P NMRS. At baseline, GSD1 patients exhibited significantly lower rates of EGP (0.53 ± 0.04 vs. 1.74 ± 0.03 mg·kg−1·min−1; P < 0.01) but an increased intrahepatic glycogen (502 ± 89 vs. 236 ± 11 mmol/l; P = 0.05) and lipid content (16.3 ± 1.1 vs. 1.4 ± 0.4%; P < 0.001). After glucagon challenge, EGP did not change in GSD1 patients (0.53 ± 0.04 vs. 0.59 ± 0.24 mg·kg−1·min−1; P = not significant) but increased in healthy controls (1.74 ± 0.03 vs. 3.95 ± 1.34; P < 0.0001). In GSD1 patients, we found an exaggerated increase of intrahepatic phosphomonoesters (0.23 ± 0.08 vs. 0.86 ± 0.19 arbitrary units; P < 0.001), whereas inorganic phosphate decreased (0.36 ± 0.08 vs. −0.43 ± 0.17 arbitrary units; P < 0.01). Intracerebral ratios of glucose and lactate to creatine were higher in GSD1 patients ( P < 0.05 vs. control). Therefore, hepatic defects of glucose metabolism persist in young adult GSD1 patients. Upregulation of the glucose and lactate transport at the blood-brain barrier could be responsible for the amelioration of hypoglycemic symptoms.
The Interplay between Linear Representations of the Braid Group
Authors: Abdulrahim Mohammad N. , Kassem Nibal H.
Published: September 2007

We consider Wada's representation as a twisted version of the standard action of the braid group,Bn, on the free group withngenerators. Constructing a free group,Gnm, of ranknm, we compose Cohen's mapBn→Bnmand the embeddingBnm→Aut(Gnm)via Wada's map. We prove that the composition factors of the obtained representation are one copy of Burau representation andm−1copies of the standard representation after changing the parameterttotkin the definitions of the Burau and standard representations. This is a generalization of our previous result concerning the standard Artin representation of the braid group.
Polynomial Rings over Pseudovaluation Rings
Authors: Bhat V. K.
Published: September 2007

LetRbe a ring. Letσbe an automorphism ofR. We define aσ-divided ring and prove the following. (1) LetRbe a commutative pseudovaluation ring such thatx∉Pfor anyP∈Spec(R[x,σ]). ThenR[x,σ]is also a pseudovaluation ring. (2) LetRbe aσ-divided ring such thatx∉Pfor anyP∈Spec(R[x,σ]). ThenR[x,σ]is also aσ-divided ring. Let nowRbe a commutative NoetherianQ-algebra (Qis the field of rational numbers). Letδbe a derivation ofR. Then we prove the following. (1) LetRbe a commutative pseudovaluation ring. ThenR[x,δ]is also a pseudovaluation ring. (2) LetRbe a divided ring. ThenR[x,δ]is also a divided ring.
Broadband Ferromagnetic Resonance Measurements in Ni/ZnO and Niγ-Fe2O3Nanocomposites
Authors: Castel Vincent , Ben Youssef Jamal , Brosseau Christian
Published: September 2007

A comparative study at the ambient temperature of the ferromagnetic resonance (FMR) spectra of Ni/ZnO andNi/γ-Fe2O3nanocomposites (NCs) is reported. A microstrip transmission line technique was used to measure the FMR profiles and linewidths in the 8–24 GHz frequency range. The samples were placed at the center of a microstrip line where the derivative of the absorbed power was measured using a standard ac field modulation technique (10 Oe amplitude) and lock-in detection. The analysis of the FMR spectra can be interpreted as arising from aggregates of magnetic nanoparticles, each of which resonates in an effective magnetic field composed of the applied field, the average (magnetostatic) dipolar field, and the randomly oriented magnetic anisotropy field. It is found that frequency and applied magnetic field strongly influence the lineshape of the FMR spectra. Two observations are identified within the FMR spectra. On the one hand, the resonance field increased linearly with frequency as expected from uniform mode theory and yielded a Landégfactor in the range 1.48–2.05. On the other hand, there is no clear correlation between FMR linewidths and frequency. Inhomogeneity-based line-broadening mechanisms, due to the damping of surface/interface effects and interparticle interaction, affect the FMR effective linewidth.
Synthesis and Bioconjugation of Gold Nanoparticles as Potential Molecular Probes for Light‐Based Imaging Techniques
Authors: Rayavarapu Raja Gopal , Petersen Wilma , Ungureanu Constantin , Post Janine N. , van Leeuwen Ton G. , Manohar Srirang
Published: September 2007

We have synthesized and characterized gold nanoparticles (spheres and rods) with optical extinction bands within
the “optical imaging window.” The intense plasmon resonant driven absorption and scattering peaks of these nanoparticles
make them suitable as contrast agents for optical imaging techniques. Further, we have conjugated these gold nanoparticles
to a mouse monoclonal antibody specific to HER2 overexpressing SKBR3 breast carcinoma cells. The bioconjugation
protocol uses noncovalent modes of binding based on a combination of electrostatic and hydrophobic interactions of
the antibody and the gold surface. We discuss various aspects of the synthesis and bioconjugation protocols and the
characterization results of the functionalized nanoparticles. Some proposed applications of these potential molecular
probes in the field of biomedical imaging are also discussed.
A Bioreactor Model of Mouse Tumor Progression
Authors: Thouas George A. , Sheridan John , Hourigan Kerry
Published: September 2007

The present study represents an investigation of a novel stirred bioreactor for culture of a transformed cell line under defined hydrodynamic conditions in vitro. Cell colonies of the EL-4 mouse lymphoma cell line grown for the first time in a rotating disc bioreactor (RDB), were observed to undergo changes in phenotype in comparison to standard, static flask cultures. RDB cultures, with or without agitation, promoted the formation of adherent EL-4 cell plaques that merged to form contiguous tumor-like masses in longer-term cultures, unlike the unattached spheroid aggregates of flask cultures. Plaques grown under agitated conditions were further altered in morphology and distribution in direct response to fluid mechanical stimuli. Plaque colonies growth in RDBs with or without agitation also exhibited significant increases in production of interleukin-4 (IL-4) and lactate, suggesting an inducible “Warburg effect.” Increases in cell biomass in RDB cultures were no different to flask cultures, though a trend toward a marginal increase was observed at specific rotational speeds. The RDB may therefore be a suitable alternative method to study mechanisms of tumor progression and invasiveness in vitro, under more complex physicochemical conditions that may approximate natural tissue environments.
Extracting Rhythmic Brain Activity for Brain-Computer Interfacing through Constrained Independent Component Analysis
Authors: Wang Suogang , James Christopher J.
Published: September 2007

We propose a technique based on independent component analysis (ICA) with constraints, applied to the rhythmic electroencephalographic (EEG) data recorded from a brain-computer interfacing (BCI) system. ICA is a technique that can decompose the recorded EEG into its underlying independent components and in BCI involving motor imagery, the aim is to isolate rhythmic activity over the sensorimotor cortex. We demonstrate that, through the technique of spectrally constrained ICA, we can learn a spatial filter suited to each individual EEG recording. This can effectively extract discriminatory information from two types of single-trial EEG data. Through the use of the ICA algorithm, the classification accuracy is improved by about 25%, on average, compared to the performance on the unpreprocessed data. This implies that this ICA technique can be reliably used to identify and extract BCI-related rhythmic activity underlying the recordings where a particular filter is learned for each subject. The high classification rate and low computational cost make it a promising algorithm for application to an online BCI system.
Identifying Opportunities for Exploiting Cross-Layer Interactions in Adaptive Wireless Systems
Authors: Weingart Troy , Sicker Douglas C. , Grunwald Dirk
Published: September 2007

The flexibility of cognitive and software-defined radio heralds an opportunity for researchers to reexamine how network protocol layers operate with respect to providing quality of service aware transmission among wireless nodes. This opportunity is enhanced by the continued development of spectrally responsive devices—ones that can detect and respond to changes in the radio frequency environment. Present wireless network protocols define reliability and other performance-related tasks narrowly within layers. For example, the frame size employed on 802.11 can substantially influence the throughput, delay, and jitter experienced by an application, but there is no simple way to adapt this parameter. Furthermore, while the data link layer of 802.11 provides error detection capabilities across a link, it does not specify additional features, such as forward error correction schemes, nor does it provide a means for throttling retransmissions at the transport layer (currently, the data link and transport layer can function counterproductively with respect to reliability). This paper presents an analysis of the interaction of physical, data link, and network layer parameters with respect to throughput, bit error rate, delay, and jitter. The goal of this analysis is to identify opportunities where system designers might exploit cross-layer interactions to improve the performance of Voice over IP (VoIP), instant messaging (IM), and file transfer applications.
Fixed Points and Hyers-Ulam-Rassias Stability of Cauchy-Jensen Functional Equations in Banach Algebras
Authors: Park Choonkil
Published: September 2007

We prove the Hyers-Ulam-Rassias stability of homomorphisms in real Banach algebras and of generalized derivations on real Banach algebras for the following Cauchy-Jensen functional equations: "Equation missing", "Equation missing", which were introduced and investigated by Baak (2006). The concept of Hyers-Ulam-Rassias stability originated from Th. M. Rassias' stability theorem that appeared in his paper (1978).
On the Composition of Distributionsx−sln|x|and|x|μ
Authors: Jolevska-Tuneska Biljana , Özça¯g Emin
Published: September 2007

LetFbe a distribution and letfbe a locally summable function. The distributionF(f)is defined as the neutrix limit of the sequence{Fn(f)}, whereFn(x)=F(x)*δn(x)and{δn(x)}is a certain sequence of infinitely differentiable functions converging to the Dirac delta-functionδ(x). The composition of the distributionsx−sIn|x|and|x|μis evaluated fors=1,2,…,μ>0andμs≠1,2,….
Genome Mapping and Molecular Breeding of Tomato
Authors: Foolad Majid R.
Published: September 2007

The cultivated tomato, Lycopersicon esculentum, is the second most consumed vegetable worldwide and a well-studied crop species in terms of genetics, genomics, and breeding. It is one of the earliest crop plants for which a genetic linkage map was constructed, and currently there are several molecular maps based on crosses between the cultivated and various wild species of tomato. The high-density molecular map, developed based on an L. esculentum×L. pennellii cross, includes more than 2200 markers with an average marker distance of less than 1 cM and an average of 750 kbp per cM. Different types of molecular markers such as RFLPs, AFLPs, SSRs, CAPS, RGAs, ESTs, and COSs have been developed and mapped onto the 12 tomato chromosomes. Markers have been used extensively for identification and mapping of genes and QTLs for many biologically and agriculturally important traits and occasionally for germplasm screening, fingerprinting, and marker-assisted breeding. The utility of MAS in tomato breeding has been restricted largely due to limited marker polymorphism within the cultivated species and economical reasons. Also, when used, MAS has been employed mainly for improving simply-inherited traits and not much for improving complex traits. The latter has been due to unavailability of reliable PCR-based markers and problems with linkage drag. Efforts are being made to develop high-throughput markers with greater resolution, including SNPs. The expanding tomato EST database, which currently includes ∼214 000 sequences, the new microarray DNA chips, and the ongoing sequencing project are expected to aid development of more practical markers. Several BAC libraries have been developed that facilitate map-based cloning of genes and QTLs. Sequencing of the euchromatic portions of the tomato genome is paving the way for comparative and functional analysis of important genes and QTLs.
Nonlinear Integrodifferential Equations of Mixed Type in Banach Spaces
Authors: Sikorska-Nowak Aneta , Nowak Grzegorz
Published: September 2007

We prove two existence theorems for the integrodifferential equation of mixed type:x'(t)=f(t,x(t),∫0tk1(t,s)g(s,x(s))ds,∫0ak2(t,s)h(s,x(s))ds),x(0)=x0, where in the first part of this paperf, g, h, xare functions with values in a Banach spaceEand integrals are taken in the sense of Henstock-Kurzweil (HK). In the second partf, g, h, xare weakly-weakly sequentially continuous functions and integrals are taken in the sense of Henstock-Kurzweil-Pettis (HKP) integral. Additionally, the functionsf, g, h, xsatisfy some conditions expressed in terms of the measure of noncompactness or the measure of weak noncompactness.
A New Statistical-Based Correlation for the Rib Fin Effects on the Overall Heat Transfer Coefficient in a Rib-Roughened Cooling Channel
Authors: Taslim M. E. , Nezym V.
Published: September 2007

Heat transfer coefficients in the cooling cavities of turbine airfoils are greatly enhanced by the presence of discrete ribs on the cavity walls. These ribs introduce two heat transfer enhancing features: a significant increase in heat transfer coefficient by promoting turbulence and mixing, and an increase in heat transfer area. Considerable amount of data are reported in open literature for the heat transfer coefficients both on the rib surface and on the floor area between the ribs. Many airfoil cooling design software tools, however, require an overall average heat transfer coefficient on a rib-roughened wall. Dealing with a complex flow circuit in conjunction with180∘bends, numerous film holes, trailing-edge slots, tip bleeds, crossover impingement, and a conjugate heat transfer problem; these tools are not often able to handle the geometric details of the rib-roughened surfaces or local variations in heat transfer coefficient on a rib-roughened wall. On the other hand, assigning an overall area-weighted average heat transfer coefficient based on the rib and floor area and their corresponding heat transfer coefficients will have the inherent error of assuming a 100% fin efficiency for the ribs, that is, assuming that rib surface temperature is the same as the rib base temperature. Depending on the rib geometry, this error could produce an overestimation of up to 10% in the evaluated rib-roughened wall heat transfer coefficient. In this paper, a correction factor is developed that can be applied to the overall area-weighted average heat transfer coefficient that, when applied to the projected rib-roughened cooling cavity walls, the net heat removal from the airfoil is the same as that of the rib-roughened wall. To develop this correction factor, the experimental results of heat transfer coefficients on the rib and on the surface area between the ribs are combined with about 400 numerical conduction models to determine an overall equivalent heat transfer coefficient that can be used in airfoil cooling design software. A well-known group method of data handling (GMDH) scheme was then utilized to develop a correlation that encompasses most pertinent parameters including the rib geometry, rib fin efficiency, and the rib and floor heat transfer coefficients.
10th Jubilee Multidisciplinary International Conference of Neuroscience and Biological Psychiatry “Stress and Behavior”
Authors: Kalueff Allan V.
Published: September 2007

St. Petersburg (Russia) hosted the 10th Jubilee Multidisciplinary Conference Stress and Behavior during May 1620, 2007. The conference featured many foremost researchers speaking on recent developments on topics such as the role of neural plasticity, memory, learning, genetics, neuromediators, transporters, and steroids in stress research, spanning disciplines from fields ranging from neurogenetics to clinical psychiatry. The conference was attended by 700 delegates from over 40 nations.
Review of Recent Progress in Dye-Sensitized Solar Cells
Authors: Kong Fan-Tai , Dai Song-Yuan , Wang Kong-Jia
Published: September 2007

We introduced the structure and the principle of dye-sensitized solar cell (DSC). The latest results about the critical technology and the industrialization research on dye-sensitized solar cells were reviewed. The development of key components, including nanoporous semiconductor films, dye sensitizers, redox electrolyte, counter electrode, and conducting substrate in dye-sensitized solar cells was reviewed in detail. The developing progress and prospect of dye-sensitized solar cells from small cells in the laboratory to industrialization large-scale production were reviewed. At last, the future development of DSC was prospective for the tendency of dye-sensitized solar cells.
The Estimation of Cortical Activity for Brain-Computer Interface: Applications in a Domotic Context
Authors: Babiloni F. , Cincotti F. , Marciani M. , Salinari S. , Astolfi L. , Tocci A. , Aloise F. , Fallani F. De Vico , Bufalari S. , Mattia D.
Published: September 2007

In order to analyze whether the use of the cortical activity, estimated from noninvasive EEG recordings, could be useful to detect mental states related to the imagination of limb movements, we estimate cortical activity from high-resolution EEG recordings in a group of healthy subjects by using realistic head models. Such cortical activity was estimated in region of interest associated with the subject's Brodmann areas by using a depth-weighted minimum norm technique. Results showed that the use of the cortical-estimated activity instead of the unprocessed EEG improves the recognition of the mental states associated to the limb movement imagination in the group of normal subjects. The BCI methodology presented here has been used in a group of disabled patients in order to give them a suitable control of several electronic devices disposed in a three-room environment devoted to the neurorehabilitation. Four of six patients were able to control several electronic devices in this domotic context with the BCI system.
About Some Linear Operators
Authors: Pop Ovidiu T.
Published: September 2007

Using the method of Jakimovski and Leviatan from their work in 1969, we construct a general class of linear positive operators. We study the convergence, the evaluation for the rate of convergence in terms of the first modulus of smoothness and we give a Voronovskaja-type theorem for these operators.
The Study of Influence of the Teslar Technology on Aqueous Solution of Some Biomolecules
Authors: Andreev E. , Dovbeshko G. , Krasnoholovets V.
Published: September 2007

The possibility of recording physical changes in aqueos solutions caused by a unique field generated by the Teslar chip (TC) inside a quartz wristwatch has been studied using holographic interferometry. We show that the refraction index of degassed pure distilled water and aqueous solutions of L-tyrosine and b-alanine affected by the TC does not change during the first 10 minutes of influence. In contrast, a 1% aqueous solution of plasma extracted from the blood of a patient with heart vascular disease changes the refractive index when affected by the TC. The characteristic time of reaction is about 102 seconds. Based on our prior research experience, we state that the response of the system studied to the TC's field is similar to that stipulated by the action of a constant magnetic field with the intensity of 1.1×10−3 T. Nevertheless,
our team have unambiguously proved that the
TC generates the inerton field,
which is associated with a substructure of
the matter waves (and, therefore, it does not relate to
the electromagnetic nature).
We could unambiguously prove that the TC generates the inerton field.
Activation of Insulin-like Growth Factor Signaling Induces Apoptotic Cell Death Under Prolonged Hypoxia by Enhancing Endoplasmic Reticulum Stress Response
Authors: Endo Hiroko , Murata Kohei , Mukai Mutsuko , Ishikawa Osamu , Inoue Masahiro
Published: September 2007

Malignant cells in solid tumors survive under prolonged hypoxia and can be a source of resistance to current cancer therapies. Mammalian target of rapamycin (mTOR), one of the downstream molecules of the insulin-like growth factor (IGF) pathway, is a key regulator of translation, integrating multiple environmental and nutritional cues. The activity of mTOR is known to be suppressed under hypoxic conditions in cancer cells, whereas the contribution of this suppression to cell survival has not yet been clarified. We show that stimulating IGF signaling provoked caspase-dependent apoptosis under low oxygen tension in two cancer cell lines, COLO 320 and AsPC-1. In concurrence with increased levels of BAD phosphorylation, cell death was not accompanied by cytochrome c release from mitochondria. The cells were rescued from apoptosis when phosphatidylinositol 3-kinase (PI3K) or mTOR activity was inhibited, suggesting that these signals are critical in the observed cell death. IGFs and insulin enhanced the endoplasmic reticulum (ER) stress response as monitored by induction of the CCAAT/enhancer binding protein homologous protein (CHOP) proteins and the X box protein-1 splicing under hypoxic conditions, and this response was suppressed by inhibiting PI3K and mTOR activity. IGF-induced cell death under hypoxic conditions was prevented by treatment with cycloheximide, suggesting that de novo protein synthesis is required. Indeed, suppression of CHOP protein levels with small hairpin RNA reduced cell death. Taken together, the data suggest that stimulating IGF signaling under hypoxic conditions provokes apoptosis by enhancing the ER stress response. [Cancer Res 2007;67(17):8095–103]
Human Thyroid Tumor Cell Lines Derived from Different Tumor Types Present a Common Dedifferentiated Phenotype
Authors: van Staveren Wilma C.G. , Solís David Weiss , Delys Laurent , Duprez Laurence , Andry Guy , Franc Brigitte , Thomas Gerry , Libert Frédérick , Dumont Jacques E. , Detours Vincent , Maenhaut Carine
Published: September 2007

Cell lines are crucial to elucidate mechanisms of tumorigenesis and serve as tools for cancer treatment screenings. Therefore, careful validation of whether these models have conserved properties of in vivo tumors is highly important. Thyrocyte-derived tumors are very interesting for cancer biology studies because from one cell type, at least five histologically characterized different benign and malignant tumor types can arise. To investigate whether thyroid tumor–derived cell lines are representative in vitro models, characteristics of eight of those cell lines were investigated with microarrays, differentiation markers, and karyotyping. Our results indicate that these cell lines derived from differentiated and undifferentiated tumor types have evolved in vitro into similar phenotypes with gene expression profiles the closest to in vivo undifferentiated tumors. Accordingly, the absence of expression of most thyrocyte-specific genes, the nonresponsiveness to thyrotropin, as well as their large number of chromosomal abnormalities, suggest that these cell lines have acquired characteristics of fully dedifferentiated cells. They represent the outcome of an adaptation and evolution in vitro, which questions the reliability of these cell lines as models for differentiated tumors. However, they may represent useful models for undifferentiated cancers, and by their comparison with differentiated cells, can help to define the genes involved in the differentiation/dedifferentiation process. The use of any cell line as a model for a cancer therefore requires prior careful and thorough validation for the investigated property. [Cancer Res 2007;67(17):8113–20]