bluuebunny/crossref_metadata_2025 huggingface dataset:
Sleep-dependent changes in the coupling between heart period and blood pressure in human subjects
Authors: Silvani Alessandro , Grimaldi Daniela , Vandi Stefano , Barletta Giorgio , Vetrugno Roberto , Provini Federica , Pierangeli Giulia , Berteotti Chiara , Montagna Pasquale , Zoccoli Giovanna , Cortelli Pietro
Published: February 2008

We investigated whether in human subjects, the pattern of coupling between the spontaneous fluctuations of heart period (HP) and those of systolic blood pressure (SBP) differs among wake-sleep states. Polysomnographic recordings and finger blood pressure measurements were performed for 48 h in 15 nonobese adults without sleep-disordered breathing. The cross-correlation function (CCF) between the fluctuations of HP and SBP at frequencies <0.15 Hz was computed during quiet wakefulness (QW), light (stages 1 and 2) and deep (stages 3 and 4) nonrapid-eye-movement sleep (NREMS), and rapid-eye-movement sleep (REMS). A positive correlation between HP and the previous SBP values, which is the expected result of baroreflex feedback control, was observed in the sleep states but not in QW. In deep NREMS, the maximum CCF value was significantly higher than in any other state, suggesting the greatest baroreflex contribution to the coupling between HP and SBP. A negative correlation between HP and the subsequent SBP values was also observed in each state, consistent with the mechanical feed-forward action of HP on SBP and with central autonomic commands. The contribution of these mechanisms to the coupling between HP and SBP, estimated from the minimum CCF value, was significantly lower in deep NREMS than either in light NREMS or QW. These results indicate that the pattern of coupling between HP and SBP at low frequencies differs among wake-sleep states in human subjects, with deep NREMS entailing the highest feedback contribution of the baroreflex and a low effectiveness of feed-forward mechanisms.
MCP-1/CCL2: a new diagnostic marker and therapeutic target for progressive renal injury in diabetic nephropathy
Authors: Tesch G. H.
Published: February 2008

Despite current therapies, many diabetic patients will suffer from declining renal function in association with progressive kidney inflammation. Recently, animal model studies have demonstrated that kidney macrophage accumulation is a critical factor in the development of diabetic nephropathy. However, specific anti-inflammatory strategies are not yet being considered for the treatment of patients with diabetic renal injury. This review highlights the chemokine monocyte chemoattractant protein-1 (MCP-1)/CC-chemokine ligand 2 as a major promoter of inflammation, renal injury, and fibrosis in diabetic nephropathy. Researchers have found that diabetes induces kidney MCP-1 production and that urine MCP-1 levels can be used to assess renal inflammation in this disease. In addition, genetic deletion and molecular blocking studies in rodents have identified MCP-1 as an important therapeutic target for treating diabetic nephropathy. Evidence also suggests that a polymorphism in the human MCP-1 gene is associated with progressive kidney failure in type 2 diabetes, which may identify patients at higher risk who need additional therapy. These findings provide a strong rationale for developing specific therapies against MCP-1 and inflammation in diabetic nephropathy.
NMDA receptor blocker ameliorates ischemia-reperfusion-induced renal dysfunction in rat kidneys
Authors: Yang Chih-Ching , Chien Chiang-Ting , Wu Ming-Hsiou , Ma Ming-Chieh , Chen Chau-Fong
Published: February 2008

N-methyl-d-aspartate (NMDA) receptor activated by glutamate/glycine is located in the kidneys. The NMDA receptor subunit NR1 is increased in damaged renal tissue. This study explored the role of NMDA receptors in ischemia-reperfusion-induced renal dysfunction in rats. With Western blot analysis and renal functional assay, NMDA receptor expression was evaluated, as well as its functional role in female Wistar rat kidneys after 45 min of unilateral ischemia followed by 24 h of reperfusion. The effects of intrarenal NMDA receptor agonist and antagonist on renal blood flow (RBF), glomerular filtration rate (GFR), urine volume (UV), sodium (UNaV), and potassium (UKV) excretion were determined. NMDA NR1 was present in the glomeruli, brush-border membrane, and outer medulla but not in the cortex and inner medulla. Homogenous distribution of non-NMDA GluR2/3, sparse kainate KA1, and undetectable group I of metabotropic glutamate receptor were noted in the control kidneys. Ischemia-reperfusion kidneys showed enhanced renal NR1, but not NR2C and GluR2/3 expression, and were associated with decreased GFR/RBF and natriuretic/diuretic responses. Intrarenal NMDA agonists significantly reduced GFR, UV, UNaV, and UKV but had no effect on blood pressure and RBF in sham control and ischemia-reperfusion kidneys. NMDA antagonist d-2-amino-5-phosphonopentanoic acid (D-AP-5) treatment completely abolished NMDA-induced renal dysfunction. D-AP-5 treatment significantly ameliorated ischemia-reperfusion-induced glomerular and tubular dysfunction by restoring decreased GFR, UV, and UNaV levels. Ischemia-reperfusion upregulates renal NMDA NR1 receptor expression, leading to reduced glomerular and tubular function in the kidneys. The NMDA antagonist can ameliorate ischemia-reperfusion-induced renal dysfunction.
Angiotensin II stimulates elution of Na-K-ATPase from a digoxin-affinity column by increasing the kinetic response to ligands that trigger the decay of E2-P
Authors: Yingst Douglas R. , Doci Tabitha M. , Massey Katherine J. , Rossi Noreen F. , Rucker Ebony , Mattingly Raymond R.
Published: February 2008

We earlier observed that treating rat proximal tubules with concentrations of angiotensin II (ANG II) that directly stimulate Na-K-ATPase activity changed how Na-K-ATPase subsequently eluted from an ouabain-affinity column. In this study we tested whether ANG II increases the rate of elution in response to ligands that trigger the decay of E2-P, which implies a change in functional properties of Na-K-ATPase, or by decreasing the amount subsequently eluted with SDS, which suggests a change in how Na-K-ATPase interacts with other proteins. We utilized a new digoxin-affinity column and novel lines of opossum kidney (OK) cells that coexpress the rat AT1areceptor and either the wild-type rat α1-isoform of Na-K-ATPase or a truncation mutant missing the first 32 amino acids of its NH2terminus. We characterized how rat kidney microsomes bind to and elute from the digoxin-affinity column and demonstrated that they are heterogeneous in the rate at which they release digoxin in response to ligands that trigger the decay of E2-P. Incubating OK cells with ANG II stimulated the ensuing elution of wild-type rat α1-subunit by increasing the kinetic response to ligands that cause a decay of E2-P without affecting the amount later eluted with SDS. In contrast, ANG II had no effect on the kinetic response of the truncation mutant but decreased the amount eluted with SDS. These data suggest that ANG II regulates both the kinetic properties of Na-K-ATPase and its interaction with other proteins by a mechanism(s) involving its NH2terminus.
Renal ischemia reperfusion inhibits VEGF expression and induces ADAMTS-1, a novel VEGF inhibitor
Authors: Basile David P. , Fredrich Katherine , Chelladurai Bhadrani , Leonard Ellen C. , Parrish Alan R.
Published: February 2008

Reductions in vascular density occur following acute ischemia-reperfusion (I/R) injury that may predispose the development of chronic kidney disease. The mechanisms mediating vascular loss are not clear but may relate to the lack of effective vascular repair responses. To determine the regulation of the VEGF/VEGFR pathway following I/R injury, male Sprague-Dawley rats were subjected to bilateral renal ischemia (45 min) and allowed to recover for 1, 3, 7, and 35 days. VEGF mRNA expression was repressed by greater than 50% of control values up to 3 days postischemia, while VEGF protein was repressed for up to 7 days postischemia. The renal mRNA expression of receptors was not altered postischemia; however, VEGFR1 (flt-1) protein was transiently reduced in kidney while soluble flt-1 was elevated in plasma at 7 days following injury. Microarray analysis of angiogenesis-related genes identified the enhanced expression of a number of genes, among these was ADAMTS-1 (a disintegrin and metalloproteinase with thrombospondin motif-1), a secreted VEGF inhibitor. The altered expression of ADAMTS-1 was confirmed using RT-PCR and Western blot analysis; immunofluorescence localized its expression to proximal tubules following I/R injury. Other genes identified using microarray included aminopeptidase N, Smad-1, and Id-3 and their localization was also examined using immunohistochemistry. In summary, the data indicate no clear pattern of anti-angiogenic gene expression following renal I/R injury. However, the studies do suggest an overall inhibition of the VEGF pathway during the early injury and repair phase of renal ischemia that may contribute to an overall reduction in renal microvascular density.
Surfactant proteins B and C are both necessary for alveolar stability at end expiration in premature rabbits with respiratory distress syndrome
Authors: Almlén Andreas , Stichtenoth Guido , Linderholm Bim , Haegerstrand-Björkman Marie , Robertson Bengt , Johansson Jan , Curstedt Tore
Published: February 2008

Modified natural surfactant preparations, used for treatment of respiratory distress syndrome in premature infants, contain phospholipids and the hydrophobic surfactant protein (SP)-B and SP-C. Herein, the individual and combined effects of SP-B and SP-C were evaluated in premature rabbit fetuses treated with airway instillation of surfactant and ventilated without positive end-expiratory pressure. Artificial surfactant preparations composed of synthetic phospholipids mixed with either 2% (wt/wt) of porcine SP-B, SP-C, or a synthetic poly-Leu analog of SP-C (SP-C33) did not stabilize the alveoli at the end of expiration, as measured by low lung gas volumes of ∼5 ml/kg after 30 min of ventilation. However, treatment with phospholipids containing both SP-B and SP-C/SP-C33 approximately doubled lung gas volumes. Doubling the SP-C33 content did not affect lung gas volumes. The tidal volumes were similar in all groups receiving surfactant. This shows that SP-B and SP-C exert different physiological effects, since both proteins are needed to establish alveolar stability at end expiration in this animal model of respiratory distress syndrome, and that an optimal synthetic surfactant probably requires the presence of mimics of both SP-B and SP-C.
Absence of Gamma-Range Corticomuscular Coherence During Dynamic Force in a Deafferented Patient
Authors: Patino Luis , Omlor Wolfgang , Chakarov Vihren , Hepp-Reymond Marie-Claude , Kristeva Rumyana
Published: February 2008

Recently, we studied corticomuscular coherence (CMC) in a visuomotor task and showed for the first time gamma-range (30–45 Hz) CMC during isometric compensation of a periodically modulated dynamic force. We speculated that for the control of such forces, the sensorimotor system resonates at gamma-range frequencies to rapidly integrate the visual and proprioceptive information and produce the appropriate motor command. In this study, we tested the role of the proprioceptive afferent feedback on gamma-range CMC by comparing the deafferented patient GL to six age- and sex-matched subjects during the performance of a visuomotor force task consisting of isometric compensation of static and dynamic forces applied on the finger. Patient GL presented no significant gamma-band CMC during dynamic force. Instead, she had only beta-range CMC as in the static force condition; concurrently, her performance was significantly worse than that of the controls in both conditions. This gives support to the conclusions of our previous paper and suggests that proprioceptive information is mandatory in the genesis of gamma-band CMC during the generation and control of dynamic forces.
Sophisticated Temporal Pattern Recognition in Retinal Ganglion Cells
Authors: Schwartz Greg , Berry Michael J.
Published: February 2008

Pattern recognition is one of the most important tasks of the visual system, and uncovering the neural mechanisms underlying recognition phenomena has been a focus of researchers for decades. Surprisingly, at the earliest stages of vision, the retina is capable of highly sophisticated temporal pattern recognition. We stimulated the retina of tiger salamander ( Ambystoma tigrinum) with periodic dark flash sequences and found that retinal ganglion cells had a wide variety of different responses to a periodic flash sequence with many firing when a flash was omitted. The timing of the omitted stimulus response (OSR) depended on the period, with individual cells tracking the stimulus period down to increments of 5 ms. When flashes occurred earlier than expected, cells updated their expectation of the next flash time by as much as 50 ms. When flashes occurred later than expected, cells fired an OSR and reset their temporal expectation to the average time interval between flashes. Using pharmacology to investigate the retinal circuitry involved, we found that inhibitory transmission from amacrine cells was not required, but on bipolar cells were required. The results suggest a mechanism in which the intrinsic resonance of on bipolars leads to the OSR in ganglion cells. We discuss the implications of retinal pattern recognition on the neural code of the retina and visual processing in general.
Location of Spinal Cord Pathways That Control Hindlimb Movement Amplitude and Interlimb Coordination During Voluntary Swimming in Turtles
Authors: Samara Ramsey F. , Currie Scott N.
Published: February 2008

We performed mechanical lesions of the midbody (D2–D3; second to third postcervical spinal segments) spinal cord in otherwise intact turtles to locate spinal cord pathways that 1) activate and control the amplitude of voluntary hindlimb swimming movements and 2) coordinate hindlimb swimming with the movement of other limbs. Pre- and postlesion turtles were held by a band clamp around the carapace just beneath the water surface in a clear Plexiglas tank and videotaped from below so that kinematic measurements could be made of voluntary forward swimming with motion analysis software. Movements of the forelimbs (wrists) and hindlimbs (knees and ankles) were tracked relative to stationary reference points on the plastron to obtain bilateral measurements of hip and forelimb angles as functions of time along with foot trajectories. We measured changes in limb movement amplitude, cycle period, and interlimb phase before and after spinal lesions. Our results indicate that locomotor command signals that activate and regulate the amplitude of voluntary hindlimb swimming travel primarily in the dorsolateral funiculus (DLF) at the D2–D3 level and cross over to drive contralateral hindlimb movements. This suggests that electrical stimulation of the D3 DLF, which was previously shown to evoke swimming movements in the contralateral hindlimb of low-spinal turtles, activated the same locomotor command pathways that the animal uses during voluntary behavior. We also show that forelimb–hindlimb coordination is maintained by longitudinal spinal pathways that are largely confined to the ventrolateral funiculus (VLF) and mediate phase coupling of ipsilateral limbs, presumably by interenlargement propriospinal fibers.
Properties of Wild-Type and Fluorescent Protein-Tagged Mouse Tetrodotoxin-Resistant Sodium Channel (NaV1.8) Heterologously Expressed in Rat Sympathetic Neurons
Authors: Schofield Geoffrey G. , Puhl Henry L. , Ikeda Stephen R.
Published: February 2008

The tetrodotoxin (TTX)-resistant Na+ current arising from NaV1.8-containing channels participates in nociceptive pathways but is difficult to functionally express in traditional heterologous systems. Here, we show that injection of cDNA encoding mouse NaV1.8 into the nuclei of rat superior cervical ganglion (SCG) neurons results in TTX-resistant Na+ currents with amplitudes equal to or exceeding the currents arising from natively expressing channels of mouse dorsal root ganglion (DRG) neurons. The activation and inactivation properties of the heterologously expressed NaV1.8 Na+ channels were similar but not identical to native TTX-resistant channels. Most notably, the half-activation potential of the heterologously expressed NaV1.8 channels was shifted about 10 mV toward more depolarized potentials. Fusion of fluorescent proteins to the N- or C-termini of NaV1.8 did not substantially affect functional expression in SCG neurons. Unexpectedly, fluorescence was not concentrated at the plasma membrane but found throughout the interior of the neuron in a granular pattern. A similar expression pattern was observed in nodose ganglion neurons expressing the tagged channels. In contrast, expression of tagged NaV1.8 in HeLa cells revealed a fluorescence pattern consistent with sequestration in the endoplasmic reticulum, thus providing a basis for poor functional expression in clonal cell lines. Our results establish SCG neurons as a favorable surrogate for the expression and study of molecularly defined NaV1.8-containing channels. The data also indicate that unidentified factors may be required for the efficient functional expression of NaV1.8 with a biophysical phenotype identical to that found in sensory neurons.
Temporal Damping in Response to Broadband Noise. II. Auditory Nerve
Authors: Joris Philip X. , Louage Dries H. , van der Heijden Marcel
Published: February 2008

II. Auditory nerve. Low-frequency neurons in the inferior colliculus (IC) show a damped oscillatory response as a function of interaural time differences (ITDs) of broadband noise. It was previously shown that several features of such noise-delay functions are well predicted by the composite curve, generated by the linear summation of responses to tones with varying ITD. This indicates a surprising degree of linearity at the midbrain level of the auditory pathway. A similar comparison between responses to tones and to noise has not been made at a more peripheral, monaural level and it is therefore unclear to what extent this linearity reflects peripheral physiology. Here, we compare cat auditory nerve responses to broadband noise and to isolevel tones. We constructed shuffled autocorrelograms for responses to tones and summed across frequencies to obtain a monaural composite curve. We then compare this composite curve to the shuffled autocorrelogram of responses to broadband noise and find that the match between tonal and noise responses is poorer at the level of the auditory nerve than at the level of the IC. The apparent linearity of responses in the IC is thus even more surprising than was apparent from its original report because it results from mechanisms interposed between the auditory nerve and the IC.
Actions of Adenosine A2A Receptors on Synaptic Connections of Spiny Projection Neurons in the Neostriatal Inhibitory Network
Authors: Shindou Tomomi , Arbuthnott Gordon W. , Wickens Jeffery R.
Published: February 2008

There is growing evidence that adenosine plays a crucial role in basal ganglia function, particularly in the modulation of voluntary movement. An adenosine-based treatment for Parkinson's disease shows promise in recent clinical studies. Adenosine A2A receptors, the receptors involved in this treatment, are highly expressed in the neostriatum. Previous studies have suggested opposing actions of these receptors on synaptic transmission at striatal and pallidal terminals of the same spiny projection neurons, but the cells of origin of the intrastriatal terminals mediating these actions have not been identified. We used dual whole cell recordings to record simultaneously from pairs of striatal cells; this enabled definitive identification of the presynaptic and postsynaptic cells mediating the effects of A2A receptors. We found that A2A receptors facilitate GABAergic synaptic transmission by intrastriatal collaterals of the spiny projection neurons, consistent with their previously reported actions on synaptic transmission at pallidal terminals. This neuromodulatory action on lateral inhibition in the striatum may underlie, in part, the therapeutic efficacy of adenosine-based treatments for Parkinson's disease.
On the Origin of Planar Covariation of Elevation Angles During Human Locomotion
Authors: Ivanenko Y. P. , d'Avella A. , Poppele R. E. , Lacquaniti F.
Published: February 2008

Leg segment rotations in human walking covary, so that the three-dimensional trajectory of temporal changes in the elevation angles lies close to a plane. Recently the role of central versus biomechanical constraints on the kinematics control of human locomotion has been questioned. Here we show, based on both modeling and experimental data, that the planar law of intersegmental coordination is not a simple consequence of biomechanics. First, the full limb behavior in various locomotion modes (walking on inclined surface, staircase stepping, air-stepping, crouched walking, hopping) can be expressed as 2 degrees of freedom planar motion even though the orientation of the plane and pairwise segment angle correlations may differ substantially. Second, planar covariation is not an inevitable outcome of any locomotor movement. It can be systematically violated in some conditions (e.g., when stooping and grasping an object on the floor during walking or in toddlers at the onset of independent walking) or transferred into a simple linear relationship in others (e.g., during stepping in place). Finally, all three major limb segments contribute importantly to planar covariation and its characteristics resulting in a certain endpoint trajectory defined by the limb axis length and orientation. Recent advances in the neural control of movement support the hypothesis about central representation of kinematics components.
Characteristic Impedance of a Microstrip-Like Interconnect Line in Presence of Ground Plane Aperture
Authors: Sharma Rohit , Chakravarty T. , Bhooshan Sunil , Bhattacharyya A. B.
Published: February 2008

We propose new empirical expressions for the characteristic impedance of a microstrip-like interconnect line in presence of ground plane aperture.
The existing characteristic impedance expressions are modified so as to include the effect of the ground plane aperture. The variation in the characteristic impedance vis-à-vis the aperture size is established.
The proposed expressions are general and valid for a range of dielectric materials concerning MICs, RFICs, and PCBs. The results are validated by measurements performed on a vector network analyzer.
Hybrid Iteration Method for Fixed Points of Nonexpansive Mappings in Arbitrary Banach Spaces
Authors: Osilike MO , Isiogugu FO , Nwokoro PU
Published: February 2008

We prove that recent results of Wang (2007) concerning the iterative approximation of fixed points of nonexpansive mappings using a hybrid iteration method in Hilbert spaces can be extended to arbitrary Banach spaces without the strong monotonicity assumption imposed on the hybrid operator.
A Programmable Hardware Cellular Automaton: Example of Data Flow Transformation
Authors: Charbouillot Samuel , Pérez Annie , Fronte Daniele
Published: February 2008

We present an IP‐core called PHCA which stands for programmable hardware cellular automaton. PHCA is a hardware implementation of a general purpose cellular automaton (CA) entirely programmable. The heart of this structure is a PE array with reconfigurable side links allowing the implementation of a 2D CA or a 1D CA. As an illustration of a PHCA program, we present the implementation of a symmetric cryptography algorithm called ISEA for Ising spin encryption algorithm. Indeed ISEA is based on a 2D Ising spin lattice presenting random series of disordered spin configurations. The main idea of ISEA is to use this disorder to encrypt data. Efficiency of ISEA and PHCA implementation results are given.
Exposure to Forced Swim Stress Alters Local Circuit Activity and Plasticity in the Dentate Gyrus of the Hippocampus
Authors: Yarom Orli , Maroun Mouna , Richter-Levin Gal
Published: February 2008

Studies have shown that, depending on its severity and context, stress can affect neural plasticity. Most related studies focused on synaptic plasticity and long-term potentiation (LTP) of principle cells. However, evidence suggests that following high-frequency stimulation, which induces LTP in principal cells, modifications also take place at the level of complex interactions with interneurons within the dentate gyrus, that is, at the local circuit level. So far, the possible effects of stress on local circuit activity and plasticity were not studied. Therefore, we set out to examine the possible alterations in local circuit activity and plasticity following exposure to stress. Local circuit activity and plasticity were measured by using frequency dependant inhibition (FDI) and commissural modulation protocols following exposure to a 15 minute-forced swim trial. Exposure to stress did not alter FDI. The application of theta-burst stimulation (TBS) reduced FDI in both control and stressed rats, but this type of plasticity was greater in stressed rats. Commissural-induced inhibition was significantly higher in stressed rats both before and after applying theta-burst stimulation. These findings indicate that the exposure to acute stress affects aspects of local circuit activity and plasticity in the dentate gyrus. It is possible that these alterations underlie some of the behavioral consequences of the stress experience.
Inclusion Properties for Certain Subclasses of Analytic Functions Defined by a Linear Operator
Authors: Cho Nak Eun
Published: February 2008

The purpose of the present paper is to investigate some inclusion properties of certain subclasses of analytic functions associated with a family of linear operators, which are defined by means of the Hadamard product (or convolution). Some integral preserving properties are also considered.
Continuity in Partially Ordered Sets
Authors: Menon Venu G.
Published: February 2008

The notion of a continuous domain is generalized to include posets
which are not dcpos and in which the set of elements way below an
element is not necessarily directed. We show that several of the pleasing algebraic
and topological properties of domains carry over to this setting.
Psychoacoustic Music Analysis Based on the Discrete Wavelet Packet Transform
Authors: He Xing , Scordilis Michael S.
Published: February 2008

Psychoacoustical computational models are necessary for the perceptual processing of acoustic signals and have contributed significantly in the development of highly efficient audio analysis and coding. In this paper, we present an approach for the psychoacoustic analysis of musical signals based on the discrete wavelet packet transform. The proposed method mimics the multiresolution properties of the human ear closer than other techniques and it includes simultaneous and temporal auditory masking. Experimental results show that this method provides better masking capabilities and it reduces the signal‐to‐masking ratio substantially more than other approaches, without introducing audible distortion. This model can lead to greater audio compression by permitting further bit rate reduction and more secure watermarking by providing greater signal space for information hiding.
Infectomic Analysis of Gene Expression Profiles of Human Brain Microvascular Endothelial Cells Infected withCryptococcus neoformans
Authors: Jong Ambrose , Wu Chun-Hua , Zhou Wensheng , Chen Han-Min , Huang Sheng-He
Published: February 2008

In order to dissect the pathogenesis of Cryptococcus neoformans meningoencephalitis, a genomic survey of the changes in gene expression of human brain microvascular endothelial cells infected by C. neoformans was carried out in a time‐course study. Principal component analysis (PCA) revealed significant fluctuations in the expression levels of different groups of genes during the pathogen‐host interaction. Self‐organizing map (SOM) analysis revealed that most genes were up‐ or downregulated 2 folds or more at least at one time point during the pathogen‐host engagement. The microarray data were validated by Western blot analysis of a group of genes, including β‐actin, Bcl‐x, CD47, Bax, Bad, and Bcl‐2. Hierarchical cluster profile showed that 61 out of 66 listed interferon genes were changed at least at one time point. Similarly, the active responses in expression of MHC genes were detected at all stages of the interaction. Taken together, our infectomic approaches suggest that the host cells significantly change the gene profiles and also actively participate in immunoregulations of the central nervous system (CNS) during C. neoformans infection.
Diffusion Maps Clustering for Magnetic Resonance Q‐Ball Imaging Segmentation
Authors: Wassermann Demian , Descoteaux Maxime , Deriche Rachid
Published: February 2008

White matter fiber clustering aims to get insight about anatomical structures in order to generate atlases, perform clear visualizations, and compute statistics across subjects, all important and current neuroimaging problems. In this work, we present a diffusion maps clustering method applied to diffusion MRI in order to segment complex white matter fiber bundles. It is well known that diffusion tensor imaging (DTI) is restricted in complex fiber regions with crossings and this is why recent high‐angular resolution diffusion imaging (HARDI) such as Q‐Ball imaging (QBI) has been introduced to overcome these limitations. QBI reconstructs the diffusion orientation distribution function (ODF), a spherical function that has its maxima agreeing with the underlying fiber populations. In this paper, we use a spherical harmonic ODF representation as input to the diffusion maps clustering method. We first show the advantage of using diffusion maps clustering over classical methods such as N‐Cuts and Laplacian eigenmaps. In particular, our ODF diffusion maps requires a smaller number of hypothesis from the input data, reduces the number of artifacts in the segmentation, and automatically exhibits the number of clusters segmenting the Q‐Ball image by using an adaptive scale‐space parameter. We also show that our ODF diffusion maps clustering can reproduce published results using the diffusion tensor (DT) clustering with N‐Cuts on simple synthetic images without crossings. On more complex data with crossings, we show that our ODF‐based method succeeds to separate fiber bundles and crossing regions whereas the DT‐based methods generate artifacts and exhibit wrong number of clusters. Finally, we show results on a real‐brain dataset where we segment well‐known fiber bundles.
Brachypodium Genomics
Authors: Ozdemir Bahar Sogutmaz , Hernandez Pilar , Filiz Ertugrul , Budak Hikmet
Published: February 2008

Brachypodium distachyon (L.) Beauv. is a temperate wild grass species; its morphological and genomic characteristics make it a model system when compared to many other grass species. It has a small genome, short growth cycle, self-fertility, many diploid accessions, and simple growth requirements. In addition, it is phylogenetically close to economically important crops, like wheat and barley, and several potential biofuel grasses. It exhibits agricultural traits similar to those of these target crops. For cereal genomes, it is a better model than Arabidopsis thaliana and Oryza sativa (rice), the former used as a model for all flowering plants and the latter hitherto used as model for genomes of all temperate grass species including major cereals like barley and wheat. Increasing interest in this species has resulted in the development of a series of genomics resources, including nuclear sequences and BAC/EST libraries, together with the collection and characterization of other genetic resources. It is expected that the use of this model will allow rapid advances in generation of genomics information for the improvement of all temperate crops, particularly the cereals.
Multimodal Data Integration for Computer‐Aided Ablation of Atrial Fibrillation
Authors: Woo Jonghye , Hong Byung-Woo , Kumar Sunil , Basu Ray Indranill , Kuo C.-C. Jay
Published: February 2008

Image‐guided percutaneous interventions have successfully replaced invasive surgical methods in some cardiologic practice, where the use of 3D‐reconstructed cardiac images, generated by magnetic resonance imaging (MRI) and computed tomography (CT), plays an important role. To conduct computer‐aided catheter ablation of atrial fibrillation accurately, multimodal information integration with electroanatomic mapping (EAM) data and MRI/CT images is considered in this work. Specifically, we propose a variational formulation for surface reconstruction and incorporate the prior shape knowledge, which results in a level set method. The proposed method enables simultaneous reconstruction and registration under nonrigid deformation. Promising experimental results show the potential of the proposed approach.
Analysis of the Publications on the Applications of Particle Swarm Optimisation
Authors: Poli Riccardo
Published: February 2008

Particle swarm optimisation (PSO) has been enormously successful. Within little more
than a decade hundreds of papers have reported successful applications of PSO. In fact, there
are so many of them, that it is difficult for PSO practitioners and researchers to have a clear
up‐to‐date vision of what has been done in the area of PSO applications. This brief paper
attempts to fill this gap, by categorising a large number of publications dealing with PSO
applications stored in the IEEE Xplore database at the time of writing.
Computer Modeling of Displacement Cascades in Beryllium Irradiated with Intensive Neutron Flux
Authors: Troev T. , Nankov N. , Petrov L. , Popov E.
Published: February 2008

Computer simulations of the radiation defects created in beryllium irradiated by fast neutrons (E > 0.1 MeV) using
the Geant4 and SRIM packages were carried out. The atom cascade displacements in Be at a neutron fluence
of 1.6 × 1020 n/cm2 were determined to be 0.06 dpa and the helium concentration was calculated to be 168 appm. The
concentration of  6Li has been estimated to be 5% in comparison to the He concentration. Nanoscale calculations
were done in 30 × 30 × 30 nm cube of fast neutron‐irradiated Be. A correlation between the Be primary knock‐on atom
(PKA) energies and the damage cascades has been established. The final defect distributions of single vacancies,
divacancies, and small vacancy clusters were examined. Our results indicate that the damages caused by He atoms
are about 3 times less than damages caused by Be primary knock‐on atoms (PKAs).
Performance Comparison between Nonidentical Segmented Exponential Concave and Nonidentical Segmented Exponential Convex Serrated CATRs
Authors: Rama Krishna T. Venkata , Siddaiah P. , Rao B. Prabhakara
Published: February 2008

This paper presented a theoretical and numerical assessment for nonidentical segmented exponential‐ (NISE‐) convex and NISE‐concave serrated plane CATRs by changing number of serrations. The investigation was based on diffraction theory and, more specifically, on the diffraction formulation of Fresnel. The compact antenna test range (CATR) provides uniform illumination within the Fresnel region to the test antenna. Application of serrated edges has been shown to be a good method to control diffraction at the edges of the reflectors. In this paper, the Fresnel fields of NISE‐convex and NISE‐concave serrated CATRs are analyzed using physical optics (PO) technique. The PO analysis is applied in this paper for plane reflector serrated CATR only. The same analysis is applied to any type of reflector. In this paper, lens‐based reflector is not considered. It is observed that NISE‐concave serrated CATR gives less ripple and enhanced quiet zone width than NISE‐convex.
An Approximate Numerical Technique for Characterizing Optical Pulse Propagation in Inhomogeneous Biological Tissue
Authors: Handapangoda Chintha C. , Premaratne Malin
Published: February 2008

An approximate numerical technique for modeling optical pulse propagation
through weakly scattering biological tissue is developed by solving
the photon transport equation in biological tissue that includes varying
refractive index and varying scattering/absorption coefficients. The proposed
technique involves first tracing the ray paths defined by the refractive
index profile of the medium by solving the eikonal equation using
a Runge‐Kutta integration algorithm. The photon transport equation is
solved only along these ray paths, minimizing the overall computational
burden of the resulting algorithm. The main advantage of the current algorithm
is that it enables to discretise the pulse propagation space adaptively
by taking optical depth into account. Therefore, computational
efficiency can be increased without compromising the accuracy of the algorithm.
Harmonic Maps and Stability on f‐Kenmotsu Manifolds
Authors: Mangione Vittorio
Published: February 2008

The purpose of this paper is to study some submanifolds and Riemannian submersions on an f‐Kenmotsu manifold. The stability of a ϕ‐holomorphic map from a compact f‐Kenmotsu manifold to a Kählerian manifold is proven.
The Effect of Transition Metal Doping on the Photooxidation Process of Titania‐Clay Composites
Authors: Ménesi Judit , Kékesi Renáta , Kőrösi László , Zöllmer Volker , Richardt André , Dékány Imre
Published: February 2008

Montmorillonite‐TiO2 composites containing various transition metal ions (silver, copper, or nickel) were prepared, and their photocatalytic efficiencies were tested in the degradation of ethanol vapor at 70% relative humidity. Two light sources, UV‐rich (λ = 254 nm) and visible (λ = 435 nm), were used. The kinetics of degradation was monitored by gas chromatography. It was established that, in the case of each catalyst, ethanol degradation was more efficient in UV‐C (λ = 254 nm) than in visible light, furthermore, these samples containing silver or copper ions were in each case about twice more efficient than P25 TiO2 (Degussa AG.) used as a reference. In photooxidation by visible light, TiO2/clay samples doped with silver or copper were also more efficient than the reference sample, P25 TiO2. We show that doping metal ions can also be delivered to the surface of the support by ion exchange and significantly alters the optical characteristics of the TiO2/clay composite.
A Novel Soft-Switching Synchronous Buck Converter for Portable Applications
Authors: Panda Anup Kumar , Pattnaik Swapnajit , Mohapatra K. K.
Published: February 2008

This paper proposes a zero-voltage-transition (ZVT) pulse-width-modulated (PWM) synchronous buck converter, which is designed to operate at low voltage and high efficiency typically required for portable systems. A new passive auxiliary circuit that allows the main switch to operate with zero-voltage switching has been incorporated in the conventional PWM synchronous buck converter. The operation principles and a detailed steady-state analysis of the ZVT-PWM synchronous converter implemented with the auxiliary circuit are presented. Besides, the main switch and all of the semiconductor devices operate under soft-switching conditions. Thus, the auxiliary circuit provides a larger overall efficiency. The feasibility of the auxiliary circuit is confirmed by simulation and experimental results.
Peroxisome Proliferator-Activated Receptor-γ–Mediated Effects in the Vasculature
Authors: Duan Sheng Zhong , Usher Michael G. , Mortensen Richard M.
Published: February 2008

Peroxisome proliferator-activated receptor (PPAR)-γ is a nuclear receptor and transcription factor in the steroid superfamily. PPAR-γ agonists, the thiazolidinediones, are clinically used to treat type 2 diabetes. In addition to its function in adipogenesis and increasing insulin sensitivity, PPAR-γ also plays critical roles in the vasculature. In vascular endothelial cells, PPAR-γ activation inhibits endothelial inflammation by suppressing inflammatory gene expression and therefore improves endothelial dysfunction. In vascular smooth muscle cells, PPAR-γ activation inhibits proliferation and migration and promotes apoptosis. In macrophages, PPAR-γ activation suppresses inflammation by regulating gene expression and increases cholesterol uptake and efflux. A recurring theme in many cell types is the modulation of the innate immunity system particularly through altering the activity of the nuclear factor κB. This system is likely to be even more prominent in modulating disease in vascular cells. The effects of PPAR-γ in the vascular cells translate into the beneficial function of this transcription factor in vascular disorders, including hypertension and atherosclerosis. Both human genetic studies and animal studies using transgenic mice have demonstrated the importance of PPAR-γ in these disorders. However, recent clinical studies have raised significant concerns about the cardiovascular side effects of thiazolidinediones, particularly rosiglitazone. Weighing the potential benefit and harm of PPAR-γ activation and exploring the functional mechanisms may provide a balanced view on the clinical use of these compounds and new approaches to the future therapeutics of vascular disorders associated with diabetes.
What Holds Back Bangalore Businesses?
Authors: Bhidé Amar
Published: February 2008

This paper focuses on non–Information Technology businesses operating in the city of Bangalore, India. Data on firms compiled from statutory regulatory filings suggest that the number and proportion of businesses that expand rapidly are much lower than in the United States. In-depth interviews with over 100 entrepreneurs in Bangalore suggest that deficiencies in the performance of basic governmental functions (such as in collecting taxes and maintaining land records) play a significant role in discouraging businesses from starting at or expanding to an economically efficient scale of operation.
The Malaysian Capital Controls: A Success Story?
Authors: Athukorala Prema-chandra
Published: February 2008

This paper contributes to the debate on the use of temporary controls on capital outflows as a crisis resolution measure by examining the outcome of Malaysia's radical response to the 1997–98 financial crisis. The analysis suggests that carefully designed temporary capital controls were successful in providing Malaysian policymakers a viable setting for aiding the recovery process through the standard Keynesian therapy. Capital controls also assisted banking and corporate restructuring by facilitating the mobilization of domestic resources, and more importantly, by providing a cushion against possible adverse impacts on market sentiment of “national” initiatives. Of course other countries should be cautious in deriving policy lessons from Malaysia because a number of factors specific to Malaysia seem to have significantly conditioned the outcome of the capital-control based recovery package.
Indonesia's Slow Recovery After Meltdown
Authors: Azis Iwan J.
Published: February 2008

Although signs have emerged that some of the forces that caused the 1997–98 Asian financial crisis have begun to diminish and progress has been made in macroeconomic affairs, 10 years after the meltdown Indonesia's recovery is still among the slowest in Asian crisis countries. During the last few years, the relatively rapid growth of the financial sector (inadequately restructured) reflects the presence of excess liquidity and the sector's vulnerability. The slow growth of investment explains the economy-wide effects on the real sector and the stagnancy or deterioration of some social indicators. This paper focuses on two issues related to the slow recovery: the financial structure of lenders and borrowers that dampened credit, and the dismal performance of regional growth following the 2001 decentralization policy. There is some evidence indicating that agency costs have slowed credit and investment growth (credit channel), and that institutional constraints produced a lack of growth incentives among local governments. Efforts to raise the sub-national welfare post-decentralization have also been constrained by national policies such as a tight budget and the relatively conservative monetary policy despite the fact that they are not too effective at controlling inflation. The decomposition analysis also shows that an aggregate demand expansion would have been effective to stimulate growth.
The ENIAC Forecasts: A Re-creation
Authors: Lynch Peter
Published: February 2008

The numerical forecasts made in 1950 using the Electronic Numerical Integrator and Computer (ENIAC) paved the way for the remarkable advances that have been made over the past half-century in weather prediction and climate modeling. We review the circumstances in which the forecasts were made, the nature of the ENIAC machine, and the roles of the people involved. The basis for the forecasts was the barotropic vorticity equation, and the initial data were prepared manually from standard weather charts. Now that the NCEP-NCAR reanalysis extends back to 1948, the initial height fields for the forecasts are readily available in digital form. We describe the reconstruction of the forecasts using reanalyzed data.

Were the ENIAC forecasts any good? To date, no objective verification of the four integrations has been available. A comparison of the original and reconstructed forecasts shows them to be in good agreement. Quantitative verification of the forecasts yields surprising results. On the basis of root-mean-square errors, persistence beats the forecast in three of the four cases. The mean error, or bias, is smaller for persistence in all four cases. However, when SI scores are compared, all four forecasts show skill and three are substantially better than persistence.

A small modification of the prediction equation, in which the streamfunction replaces the geopotential height as the prognostic variable, can be implemented without any computational penalty. The modified equation yields slightly improved forecasts in all four cases.
Democratizing Knowledge
Authors: Carolan Michael S.
Published: February 2008

This article highlights that in our rush to call for the democratization of science and expertise we must not forget to speak to what type of democratization we are calling for. In short, not all participatory forms are the same. In developing this argument, I examine one such form that has yet to receive much attention from science and technology studies scholars: the agricultural field day. In examining the field day, we find that its orientation—that is, toward either the conventional or sustainable model of agriculture—shapes significantly its democratic approach to knowledge coproduction. To help inform how we understand conventional and sustainable field days, I turned to two conceptual frameworks of participation: namely, that of Wynne and Funtowicz and Ravetz. In doing this, we find that conventional field days mirror closely that form of public participation detailed by Funtowicz and Ravetz, while sustainable field days reflect that conceptualized by Wynne.
Agroecology as Participatory Science
Authors: Warner Keith Douglass
Published: February 2008

The discourses of agricultural extension reveal how actors represent their scientific activities and goals. The “transfer of technology” discourse developed with the professional U.S. extension service, reproducing its expert/lay power relations. Agroecology is emerging as a systems approach to preventing agricultural pollution. Its theoreticians argue that agroecology cannot be transferred like technology but must be extended through networks of participatory social learning. In California, hundreds of actors and dozens of institutions have cocreated agroecological partnerships using this alternative extension model. They have developed three alternative extension discourses to represent and explain their activities. Bruno Latour's “circulatory system of science” model provides a superior theoretical framework for interpreting the participation and discourses of diverse actors in this extension practice.