bluuebunny/crossref_metadata_2025 huggingface dataset:
THE PERFORMANCE OF DIFFERENT DITHER SIGNALS IN NONLINEAR SYSTEMS
Authors: CHEN SENG-CHI , TSAI HSUN-HENG
Published: August 2009

Dither is a high frequency signal which is introduced into a nonlinear system with the object of augmenting stability, quenching undesirable limit cycle, and altering the apparent nonlinear element characteristics. In this paper, we investigate the performance of various high frequency dither signals with different wave forms in nonlinear feedback systems. Meanwhile, an analog experimental device is set up to simulate the nonlinear systems, which consists of dither and a nonlinear element such as a relay or a limiter. A describing function and an equivalent nonlinearity method are used to evaluate the dither performance. The performance of various dither signals having a certain wave form is examined through these studies, and the results could evaluate effectiveness of these dither-injection techniques into nonlinear feedback systems.
RELATIVE STUDIES OF TRANSPORT PROPERTIES OF ZnO SUBSTITUTED LEAD VANADATE SYSTEM IN BOTH GLASS AND CRYSTALLINE FORMS
Authors: RAO B. SRINIVASA , RAMESH K. V. , SASTRY D. L.
Published: August 2009

Glasses of x( ZnO )(50 - x) PbO :50 V 2 O 5 system were prepared by melt-quench process in the range x = 0 mol % to 15 mol%. Measurements are reported for DC electrical conductivity as well as thermo electrical power for these samples in both glass and crystalline forms in the temperature range of 27°C and 227°C. The ESR studies of these samples at room temperature are reported. These spectra are characterized by well-resolved eight-line powder pattern. It is observed that the ESR spectra obtained in the crystalline form, the hyperfine structure is nearly smeared out and the spectra are characterized by a relatively broad line with an isotropic g value. The experimental results are analyzed with reference to Mott's model. The analysis shows that at high temperatures the temperature dependence of DC conductivity is consistent with Mott's model for both glass and crystalline samples. The high-temperature thermoelectric power was satisfactorily explained by Heikes' relation and the data also showed evidence of small polaron formation for glass form samples and large polaron formation in crystalline samples. These results indicate that all the glass samples lead metavanadate are n-type at room temperature and the crystalline samples are p-type at room temperature.
COMPARISON OF SiC AND ZnO FIELD EFFECT TRANSISTORS FOR HIGH POWER APPLICATIONS
Authors: ARABSHAHI H.
Published: August 2009

An ensemble Monte Carlo method is used to compare the potentialities of SiC and ZnO materials for field effect transistors. First, bulk material electron transport properties are compared and then the operation of MESFETs made from them are investigated. The simulated device geometries and doping are matched to the nominal parameters described for the experimental structures as closely as possible. Simulations of SiC MESFETs of lengths 2, 2.6 and 3.2 μm have been carried out and compared these results with those on ZnO MESFETs of the same dimensions. The direct current IV characteristics of the two materials were found to be similar, though the ZnO characteristics were on the whole superior, reaching their operating point at higher drain voltages and possessing higher gains. However, oscillations in the drain current caused by changes in drain voltage in the ZnO devices were not present to the same degree in the SiC devices. This difference is caused partially by the onset of the negative differential regime in SiC at a higher electric field than in ZnO but the primary cause is the longer ballistic transport times in SiC . This suggests that ZnO MESFETs may prove to have superior frequency response characteristics than SiC MESFETs.
INFLUENCE OF OXYGEN IMPURITY ON SEEBECK COEFFICIENT OF NANOSCALE MnSi1.7 FILMS
Authors: HOU Q. R. , CHEN Y. B. , HE Y. J.
Published: August 2009

Nano-scale MnSi 1.7 films are prepared by thermal annealing of three-layer Si / MnSi x/ Si or bi-layer Si / MnSi x (x < 1.7) structures at 923 K for 20–65 minutes. These layers are deposited on thermally oxidized silicon substrates at about 393 K by electron beam evaporation. It is found that the oxygen content in the MnSi 1.7 film can be reduced from about 10 at.% to 6 at.% by using the bi-layer structure MnSi x/ Si with the MnSi x layer on top. With the reduction of oxygen content in the MnSi 1.7 film, the transition temperature from p-type to n-type decreases from 508 K to 463 K or less.
SYNCHRONIZATION OF TAKAGI–SUGENO FUZZY STOCHASTIC DELAYED COMPLEX NETWORKS WITH HYBRID COUPLING
Authors: TANG YANG , FANG JIAN-AN
Published: August 2009

In this paper, we propose and investigate a general model of fuzzy complex networks described by the Takagi–Sugeno (T–S) fuzzy model with hybrid coupling and stochastic perturbation. The hybrid coupling includes constant coupling and discrete and distributed delay coupling. By utilizing a new Lyapunov functional form, we employ the stochastic analysis techniques and Kronecker product to develop delay-dependent synchronization criteria that ensure mean-square synchronization of the addressed T–S fuzzy delayed complex networks with stochastic disturbances. These sufficient conditions are computationally efficient, as it can be solved numerically by the LMI toolbox in Matlab. A numerical example is provided to demonstrate the effectiveness and the applicability of the proposed method.
VIBRATIONAL FREQUENCY OF IMPURITY BOUND MAGNETOPOLARON IN AN ANISOTROPIC QUANTUM DOT
Authors: XIAO WEI , XIAO JING-LIN
Published: August 2009

We study the vibrational frequency and the interaction energy of the weak-coupling impurity bound magnetopolaron in an anisotropic quantum dot. The effects of the transverse and longitudinal effective confinement lengths, the electron–phonon coupling strength, the cyclotron frequency of a magnetic field and the Coulomb bound potential are taken into consideration by using an improved linear combination operator method. It is found that the vibrational frequency and the interaction energy will increase rapidly with decreasing confinement lengths and increasing the cyclotron frequency. The vibrational frequency is an increasing function of the Coulomb bound potential, whereas the interaction energy is an decreasing one of the potential and the electron–phonon coupling strength.
Financial Contracting: A Survey of Empirical Research and Future Directions
Authors: Roberts Michael R. , Sufi Amir
Published: August 2009

We review recent evidence and future directions for empirical research on financial contracting in the context of corporate finance. Specifically, we survey evidence pertaining to incentive conflicts, control rights, collateral, renegotiation, and interactions between financial contracts and other governance mechanisms. We also discuss directions for future research, concluding that the financial contracting approach offers a potentially fruitful perspective for empirical researchers seeking to better understand a variety of issues in corporate finance including capital structure, investment policy, payout policy, and corporate governance.
Capital Market-Driven Corporate Finance
Authors: Baker Malcolm
Published: August 2009

Much of empirical corporate finance focuses on sources of the demand for various forms of capital, not the supply. Recently, this has changed. Supply effects of equity and credit markets can arise from a combination of three ingredients: investor tastes, limited intermediation, and corporate opportunism. Investor tastes when combined with imperfectly competitive intermediaries lead prices and interest rates to deviate from fundamental values. Opportunistic firms respond by issuing securities with high prices and investing the proceeds. A link between capital market prices and corporate finance can in principle come from either supply or demand. This framework helps to organize empirical approaches that more precisely identify and quantify supply effects through variation in one of these three ingredients. Taken as a whole, the evidence shows that shifting equity and credit market conditions play an important role in dictating corporate finance and investment.
The mechanical behavior of individual sarcomeres of myofibrils isolated from rabbit psoas muscle
Authors: Pavlov Ivan , Novinger Rowan , Rassier Dilson E.
Published: August 2009

The goal of this study was to develop a system to experiment with sarcomeres mechanically isolated from skeletal muscles. Single myofibrils from rabbit psoas were transferred into a temperature-controlled (22°C or 15°C) experimental chamber, and sarcomeres were isolated using precalibrated glass microneedles that were pierced externally, adjacent to the Z-lines. The force produced during activation was measured by tracking the displacement of the microneedles, and the sarcomere and half-sarcomere changes were measured by continuously tracking the Z-lines and A-bands position during the experiments. Sarcomeres produced a stress (force/cross-sectional area) of 112.75 ± 4.96 nN/μm2 (15°C) and 128.47 ± 5.58 nN/μm2 (22°C) at lengths between 2.0 μm and 2.4 μm. The descending limb was fitted with linear regression for length between 2.4 μm and 3.5 μm, which provided an abscissa extrapolating to 3.87 μm. The force-length relation was remarkably similar to a theoretical curve based on the degree of filament overlap. During sarcomere activation, we tracked the distance between the center of the A-band and the Z-lines. At lengths below 1.6 μm, movements of A-band were not detected. A-band movements increased with length to achieve a maximum displacement of 59.40 ± 10.1 nm from the center at 2.0 μm–2.4 μm. A-band displacement decreased linearly in sarcomere lengths between 2.6 μm and 3.6 μm. A technique for monitoring force and length in single sarcomeres isolated from myofibrils represents a reliable technique to evaluate contractile mechanisms at the most basic, intact level of muscle organization, opening the possibility to clarify long-standing issues in the field of muscle contraction.
Rainbow trout genetically selected for greater muscle fat content display increased activation of liver TOR signaling and lipogenic gene expression
Authors: Skiba-Cassy Sandrine , Lansard Marine , Panserat Stéphane , Médale Françoise
Published: August 2009

Genetic selection is commonly used in farm animals to manage body fat content. In rainbow trout, divergent selection for low or high muscle fat content leads to differences in utilization of dietary energy sources between the fat muscle line (FL) and the lean muscle line (LL). To establish whether genetic selection on muscle fat content affects the hepatic insulin/nutrient signaling pathway, we analyzed this pathway and the expression of several metabolism-related target genes in the livers of the two divergent lines under fasting and then refeeding conditions. Whereas glycemia returned to basal level 24 h after refeeding in FL trout, it remained elevated in the LL trout. Target of rapamycin (TOR) protein was more abundant in the livers of FL trout than in LL trout, and refeeding activation of the hepatic TOR signaling pathway (TOR, S6K1, and S6) was therefore enhanced. Genes related to glycolysis (glucokinase and pyruvate kinase) and gluconeogenesis (glucose-6-phosphatase and phosphoenolpyruvate carboxykinase) were only slightly affected by refeeding and genetic selection. Refeeding stimulated expression of lipogenic genes and the sterol-responsive element binding protein (SREBP1), and expression of fatty acid synthase, glucose-6-phosphate dehydrogenase, and serine dehydratase was predominant in the livers of FL fish compared with LL fish. In agreement with recent findings linking TOR to lipogenesis control, we concluded that genetic selection for muscle fat content resulted in overactivation of the TOR signaling pathway-associated lipogenesis and probably also improved utilization of glucose.
Effects of maternal genotype and diet on offspring glucose and fatty acid-sensing ventromedial hypothalamic nucleus neurons
Authors: Le Foll Christelle , Irani Boman G. , Magnan Christophe , Dunn-Meynell Ambrose , Levin Barry E.
Published: August 2009

Maternal obesity accentuates offspring obesity in dams bred to develop diet-induced obesity (DIO) on a 31% fat, high-sucrose, high-energy (HE) diet but has no effect on offspring of diet-resistant (DR) dams. Also, only DIO dams become obese when they and DR dams are fed HE diet throughout gestation and lactation. We assessed glucose and oleic acid (OA) sensitivity of dissociated ventromedial hypothalamic nucleus (VMN) neurons from 3- to 4-wk old offspring of DIO and DR dams fed chow or HE diet using fura-2 calcium imaging to monitor intracellular calcium fluctuations as an index of neuronal activity. Offspring of DIO dams fed chow had ∼2-fold more glucose-inhibited (GI) neurons than did DR offspring. This difference was eliminated in offspring of DIO dams fed HE diet. At 2.5 mM glucose, offspring of chow-fed DIO dams had more GI neurons that were either excited or inhibited by OA than did DR offspring. Maternal HE diet intake generally increased the percentage of neurons that were excited and decreased the percentage that were inhibited by OA in both DIO and DR offspring. However, this effect was more pronounced in DIO offspring. These data, as well as concentration-dependent differences in OA sensitivity, suggest that genotype, maternal obesity, and dietary content can all affect the sensitivity of offspring VMN neurons to glucose and long-chain fatty acids. Such altered sensitivities may underlie the propensity of DIO offspring to become obese when fed high-fat, high-sucrose diets.
Evaluation of different methods for assessment of insulin sensitivity in Göttingen minipigs: introduction of a new, simpler method
Authors: Christoffersen Berit , Ribel Ulla , Raun Kirsten , Golozoubova Valeria , Pacini Giovanni
Published: August 2009

The use of animal models in diabetes research requires reliable tests for evaluation of insulin sensitivity and β-cell function. Minipigs are being increasingly used in metabolic research, and the aim of this study was to compare different tests and indexes for evaluation of insulin sensitivity and β-cell function in Göttingen minipigs. Hyperinsulinemic, isoglycemic clamp, intravenous (IVGTT) and oral glucose tolerance tests (OGTT), and a modified insulin tolerance test were performed in minipigs fed either low- or high-energy diet. Furthermore, the reproducibility of IVGTT-derived parameters was assessed. Previously described insulin sensitivity indexes [steady-state glucose infusion rate/glucose concentration/insulin concentration from clamp (M/G/I); oral glucose insulin sensitivity (OGIS) and ISIcomp from OGTT; SI from minimal model analysis of IVGTT; and quantitative insulin sensitivity check index from fasting values] were calculated together with an insulin sensitivity index from the modified insulin tolerance test (ISIITT) and a new simple index (S2) derived from the first 30 min of the IVGTT. β-Cell function was assessed from the IVGTT and the OGTT. Reproducibility of the IVGTT-derived parameters was calculated as median intraindividual coefficient of variation (CV%).M/G/I correlated significantly only with S2 ( P < 0.05, r = 0.54). S2 furthermore correlated with SI ( P < 0.001, r = 0.81), ISIITT ( P < 0.001, r = 0.57), and the two indexes from OGTT, ISIcomp ( P < 0.001, r = 0.78) and OGIS ( p < 0.05, r = 0.48). No correlation was found between β-cell function indexes from OGTT and IVGTT. The median CV% of the new S2 index was 13. In conclusion, the new simple index of insulin sensitivity, S2, was revealed to be useful for evaluation of insulin sensitivity in pigs.
Activation of local aldosterone system within podocytes is involved in apoptosis under diabetic conditions
Authors: Lee Sun Ha , Yoo Tae-Hyun , Nam Bo-Young , Kim Dong Ki , Li Jin Ji , Jung Dong-Sub , Kwak Seung-Jae , Ryu Dong-Ryeol , Han Seung Hyeok , Lee Jung Eun , Moon Sung Jin , Han Dae Suk , Kang Shin-Wook
Published: August 2009

Previous studies have shown that mineralocorticoid receptor (MCR) blocker reduces proteinuria in diabetic nephropathy (DN), but the role of aldosterone in podocyte injury has never been explored in DN. This study was undertaken to elucidate whether a local aldosterone system existed in podocytes and to examine its role in podocyte apoptosis under diabetic conditions. In vitro, immortalized podocytes were exposed to 5.6 mM glucose (NG), NG + 24.4 mM mannitol, and 30 mM glucose (HG) with or without 10−7M spironolactone (SPR). In vivo, 32 Sprague-Dawley rats were injected with diluent (C, n = 16) or streptozotocin intraperitoneally [diabetes mellitus (DM), n = 16], and 8 rats from each group were treated with SPR for 3 mo. Aldosterone synthase (CYP11B2) and MCR mRNA and protein expression were determined by real-time PCR and Western blot, respectively, and aldosterone levels by radioimmunoassay. Western blot for apoptosis-related molecules, Hoechst 33342 staining, and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay were performed to determine apoptosis. CYP11B2 and MCR expression were significantly higher in HG-stimulated podocytes and DM glomeruli compared with NG cells and C glomeruli, respectively, along with increased aldosterone levels. Western blot analysis revealed that cleaved caspase-3 and Bax expression was significantly increased, whereas Bcl-2 expression was significantly decreased in HG-stimulated podocytes and in DM glomeruli. Apoptosis determined by Hoechst 33342 staining and TUNEL assay were also significantly increased in podocytes under diabetic conditions. These changes in the expression of apoptosis-related proteins and the increase in apoptotic cells were inhibited by SPR treatment. These findings suggest that a local aldosterone system is activated and is involved in podocyte apoptosis under diabetic conditions.
Presence of cyclic nucleotide-gated channels in the rat urethra and their involvement in nerve-mediated nitrergic relaxation
Authors: Triguero Domingo , Sancho María , García-Flores Marta , García-Pascual Ángeles
Published: August 2009

We have addressed the distribution of cGMP-gated channels (CNG) in the rat urethra for the first time, as well as their putative role in mediating of the relaxation elicited by electrical field stimulation of nitrergic nerves. Functional studies have shown that specifically blocking CNG with l- cis-diltiazem leads to the rapid inhibition of urethral relaxation induced either by nitric oxide (NO) released by the nerves or by soluble guanylate cyclase activated with YC-1. By contrast, nerve-mediated noradrenergic contractions were only slowly and mildly reduced by l- cis-diltiazem. This effect was mimicked by lower concentrations of the d-diltiazem isomer, probably due to the nonspecific inhibition of voltage-dependent calcium channels. However, d-diltiazem did not affect relaxation responses. The expression of heteromeric retinal-like CNGA1 channels was demonstrated by conventional PCR on mRNA from the rat urethra. These channels were located in a subpopulation of intramuscular interstitial cells of Cajal (ICC) as well as in smooth muscle cells, although they were less abundant in the latter. CNG channels could not be visualized in any nervous structure within the urethral wall, in agreement with the emerging view that a subset of ICC serves as a target for NO. These channels could provide a suitable ionic mechanism to associate the changes in cytosolic calcium with the activation of the nitric NO-cGMP pathway and relaxation although the precise mechanisms involved remain to be elucidated.
Functional Asymmetries Revealed in Visually Guided Saccades: An fMRI Study
Authors: Petit Laurent , Zago Laure , Vigneau Mathieu , Andersson Frédéric , Crivello Fabrice , Mazoyer Bernard , Mellet Emmanuel , Tzourio-Mazoyer Nathalie
Published: August 2009

Because eye movements are a fundamental tool for spatial exploration, we hypothesized that the neural bases of these movements in humans should be under right cerebral dominance, as already described for spatial attention. We used functional magnetic resonance imaging in 27 right-handed participants who alternated central fixation with either large or small visually guided saccades (VGS), equally performed in both directions. Hemispheric functional asymmetry was analyzed to identify whether brain regions showing VGS activation elicited hemispheric asymmetries. Hemispheric anatomical asymmetry was also estimated to assess its influence on the VGS functional lateralization. Right asymmetrical activations of a saccadic/attentional system were observed in the lateral frontal eye fields (FEF), the anterior part of the intraparietal sulcus (aIPS), the posterior third of the superior temporal sulcus (STS), the occipitotemporal junction (MT/V5 area), the middle occipital gyrus, and medially along the calcarine fissure (V1). The present rightward functional asymmetries were not related to differences in gray matter (GM) density/sulci positions between right and left hemispheres in the precentral, intraparietal, superior temporal, and extrastriate regions. Only V1 asymmetries were explained for almost 20% of the variance by a difference in the position of the right and left calcarine fissures. Left asymmetrical activations of a saccadic motor system were observed in the medial FEF and in the motor strip eye field along the Rolando sulcus. They were not explained by GM asymmetries. We suggest that the leftward saccadic motor asymmetry is part of a general dominance of the left motor cortex in right-handers, which must include an effect of sighting dominance. Our results demonstrate that, although bilateral by nature, the brain network involved in the execution of VGSs, irrespective of their direction, presented specific right and left asymmetries that were not related to anatomical differences in sulci positions.
Long-Latency Responses During Reaching Account for the Mechanical Interaction Between the Shoulder and Elbow Joints
Authors: Kurtzer Isaac , Pruszynski J. Andrew , Scott Stephen H.
Published: August 2009

Although considerable research indicates that reaching movements rely on knowledge of the arm's mechanical properties and environment to anticipate and counter predictable loads, far less research has examined whether this degree of sophistication is present for on-line corrections during reaching. Here we examine the R2/3 response to mechanical perturbations (45–100 ms, also called the long-latency reflex), which is highly flexible and includes the fastest possible contribution from primary motor cortex, a key neural substrate for self-initiated action. Torque perturbations were occasionally and unexpectedly applied to the subject's shoulder and/or elbow in the course of performing reaching movements. Critically, these perturbations would evoke different patterns of feedback corrections from a shoulder extensor muscle if it countered only the local shoulder displacement relative to unperturbed motion or accounted for the mechanical interactions between the shoulder and elbow joints and countered the underlying shoulder torque. Our results show that the earliest response (R1: 20–45 ms) reflected local shoulder displacement, whereas the R2/3 response (45–100 ms) reflected knowledge of multijoint dynamics. Moreover, the same pattern of feedback occurred whether the shoulder muscle helped initiate the movement (during its agonist phase) or helped terminate the movement (during its antagonist phase). These results contribute to the accumulating evidence that highly sophisticated feedback control underlies motor behavior and are consistent with a shared neural substrate, such as primary motor cortex, for feedforward and feedback control.
5-HT and GABA Modulate Intrinsic Excitability of Type I Interneurons in Hermissenda
Authors: Jin Nan Ge , Tian Lian-Ming , Crow Terry
Published: August 2009

The sensory neurons (photoreceptors) in the visual system of Hermissenda are one site of plasticity produced by Pavlovian conditioning. A second site of plasticity produced by conditioning is the type I interneurons in the cerebropleural ganglia. Both photoreceptors and statocyst hair cells of the graviceptive system form monosynaptic connections with identified type I interneurons. Two proposed neurotransmitters in the graviceptive system, serotonin (5-HT) and γ-aminobutyric acid (GABA), have been shown to modify synaptic strength and intrinsic neuronal excitability in identified photoreceptors. However, the potential role of 5-HT and GABA in plasticity of type I interneurons has not been investigated. Here we show that 5-HT increased the peak amplitude of light-evoked complex excitatory postsynaptic potentials (EPSPs), enhanced intrinsic excitability, and increased spike activity of identified type Ie(A) interneurons. In contrast, 5-HT decreased spike activity and intrinsic excitability of type Ie(B) interneurons. The classification of two categories of type Ie interneurons was also supported by the observation that 5-HT produced opposite effects on whole cell steady-state outward currents in type Ie interneurons. Serotonin produced a reduction in the amplitude of light-evoked complex inhibitory PSPs (IPSPs), increased spontaneous spike activity, decreased intrinsic excitability, and depolarized the resting membrane potential of identified type Ii interneurons. In contrast to the effects of 5-HT, GABA produced inhibition in both types of Ie interneurons and type Ii interneurons. These results show that 5-HT and GABA can modulate the intrinsic excitability of type I interneurons independent of the presynaptic effects of the same transmitters on excitability and synaptic efficacy of photoreceptors.
Top-Down Control of Saccades as Part of a Generalized Model of Proactive Inhibitory Control
Authors: Ballanger Bénédicte
Published: August 2009

Lo and colleagues have recently described a recurrent network model of inhibitory control of saccadic eye movements based on neurophysiological observations in the frontal eye field (FEF) and superior colliculus (SC) of rhesus monkeys. This model emphasizes the proactive, inhibition-based, tonic neuronal activity that prevents the eye from moving in a countermanding paradigm. In this review I discuss the model with respect to existing literature that the authors did not mention, suggesting that proactive inhibitory control extends far beyond saccadic control and provides an interesting framework to interpret several attentional and movement disorders in humans.
Atrial Arrhythmias After Lung Transplantation
Authors: See Vincent Y. , Roberts-Thomson Kurt C. , Stevenson William G. , Camp Phillip C. , Koplan Bruce A.
Published: August 2009

Background—

Atrial arrhythmias (AAs) including atrial fibrillation (AF) and atrial tachycardia (AT) are often observed after cardiothoracic surgery. Our aim was to evaluate the prevalence and mechanism of AAs after lung transplantation.

Methods and Results—

All patients (n=127) after bilateral sequential lung transplantation followed at our institution over 20 years were included. All patients received postoperative rhythm monitoring and clinic visits with ECG at 1, 3, 6, and 12 months, or as needed. AAs occurred in 40 of 127 (31.5%) patients over 4.2�4.1 years. AA prevalence at postoperation and 1, 3, 6, 12, and >12 months was 24%, 11%, 3%, 2%, 4%, and 11%, respectively. Early AAs were predominantly AF, whereas all AAs >12 months were AT. Time to first AF versus AT was 11�9 versus 1485�2462 days (
P
=0.09). Male sex, age, and preoperative AA predicted any early (<3 months) AA but did not predict late AA. Early AA did not predict late AT. In 4 patients with drug-resistant AT, electrophysiology studies found AT involving the pulmonary vein/left atrium anastomoses in 3 patients, including donor-to-recipient conduction in 1, border zone macroreentry in 2, and cavotricuspid isthmus dependent flutter in 1; all patients were successfully treated with ablation.

Conclusions—

AAs after lung transplantation are common. Although AF is common early, AF is rare after healing of left atrial incisions, which probably result in surgical pulmonary vein isolation with rare exception. This raises the question of whether additional surgical or ablation lines at the time of lung transplantation would prevent late AA.
Heart Valve Development
Authors: Combs Michelle D. , Yutzey Katherine E.
Published: August 2009

Abstract
:

In recent years, significant advances have been made in the definition of regulatory pathways that control normal and abnormal cardiac valve development. Here, we review the cellular and molecular mechanisms underlying the early development of valve progenitors and establishment of normal valve structure and function. Regulatory hierarchies consisting of a variety of signaling pathways, transcription factors, and downstream structural genes are conserved during vertebrate valvulogenesis. Complex intersecting regulatory pathways are required for endocardial cushion formation, valve progenitor cell proliferation, valve cell lineage development, and establishment of extracellular matrix compartments in the stratified valve leaflets. There is increasing evidence that the regulatory mechanisms governing normal valve development also contribute to human valve pathology. In addition, congenital valve malformations are predominant among diseased valves replaced late in life. The understanding of valve developmental mechanisms has important implications in the diagnosis and management of congenital and adult valve disease.
Operational Monitoring of Weather Radar Receiving Chain Using the Sun
Authors: Holleman Iwan , Huuskonen Asko , Kurri Mikko , Beekhuis Hans
Published: August 2009

A method for operational monitoring of a weather radar receiving chain, including the antenna gain and the receiver, is presented. The “online” method is entirely based on the analysis of sun signals in the polar volume data produced during operational scanning of weather radars. The method is an extension of that for determining the weather radar antenna pointing at low elevations using sun signals, and it is suited for routine application.

The solar flux from the online method agrees very well with that obtained from “offline” sun tracking experiments at two weather radar sites. Furthermore, the retrieved sun flux is compared with data from the Dominion Radio Astrophysical Observatory (DRAO) in Canada. Small biases in the sun flux data from the Dutch and Finnish radars (between −0.93 and +0.47 dB) are found. The low standard deviations of these sun flux data against those from DRAO (0.14–0.20 dB) demonstrate the stability of the weather radar receiving chains and of the sun-based online monitoring.

Results from a daily analysis of the sun signals in online radar data can be used for monitoring the alignment of the radar antenna and the stability of the radar receiver system. By comparison with the observations from a sun flux monitoring station, even the calibration of the receiving chain can be checked. The method presented in this paper has great potential for routine monitoring of weather radars in national and international networks.
A Modeling Case Study of Mixed-Phase Clouds over the Southern Ocean and Tasmania
Authors: Morrison Anthony E. , Siems Steven T. , Manton Michael J. , Nazarov Alex
Published: August 2009

The cloud structure associated with two frontal passages over the Southern Ocean and Tasmania is investigated. The first event, during August 2006, is characterized by large quantities of supercooled liquid water and little ice. The second case, during October 2007, is more mixed phase. The Weather Research and Forecasting model (WRFV2.2.1) is evaluated using remote sensed and in situ observations within the post frontal air mass. The Thompson microphysics module is used to describe in-cloud processes, where ice is initiated using the Cooper parameterization at temperatures lower than −8°C or at ice supersaturations greater than 8%. The evaluated cases are then used to numerically investigate the prevalence of supercooled and mixed-phase clouds over Tasmania and the ocean to the west. The simulations produce marine stratocumulus-like clouds with maximum heights of between 3 and 5 km. These are capped by weak temperature and strong moisture inversions. When the inversion is at temperatures warmer than −10°C, WRF produces widespread supercooled cloud fields with little glaciation. This is consistent with the limited in situ observations. When the inversion is at higher altitudes, allowing cooler cloud tops, glaciated (and to a lesser extent mixed phase) clouds are more common. The simulations are further explored to evaluate any orographic signature within the cloud structure over Tasmania. No consistent signature is found between the two cases.
Simulation of an Orographic Precipitation Event during IMPROVE-2. Part II: Sensitivity to the Number of Moments in the Bulk Microphysics Scheme
Authors: Milbrandt J. A. , Yau M. K. , Mailhot J. , Bélair S. , McTaggart-Cowan R.
Published: August 2009

This is the second in a series of papers examining the behavior of the Milbrandt–Yau multimoment bulk microphysics scheme for the simulation of the 13–14 December 2001 case of orographically enhanced precipitation observed during the second Improvement of Microphysical Parameterization through Observational Verification Experiment (IMPROVE-2) experiment. The sensitivity to the number of predicted moments of the hydrometeor size spectra in the bulk scheme was investigated. The triple-moment control simulations presented in Part I were rerun using double- and single-moment configurations of the multimoment scheme as well the single-moment Kong–Yau scheme. Comparisons of total precipitation and in-cloud hydrometeor mass contents were made between the simulations and observations, with the focus on a 2-h quasi-steady period of heavy stratiform precipitation. The double- and triple-moment simulations were similar; both had realistic precipitation fields, though generally overpredicted in quantity, and had overprediction of snow mass and an underprediction of cloud water aloft. Switching from the triple- to single-moment configuration resulted in a simulation with a precipitation pattern shifted upwind and with a larger positive bias, but with hydrometeor mass fields that corresponded more closely to the observations. Changing the particular single-moment scheme used had a greater impact than changing the number of moments predicted in the same scheme, with the Kong–Yau simulations greatly overpredicting the total precipitation in the lee side of the mountain crest and producing too much snow aloft. Further sensitivity tests indicated that the leeside overprediction in the Kong–Yau runs was most likely due to the combination of the absence of the latent heat effect term in the diffusional growth rate for snow combined with the assumption of instantaneous snow melting in the scheme.
Islam and Modernity in the Works of Two Contemporary Malay Anglophone Writers: Che Husna Azhari’s “Mariah” and Karim Raslan’s “Neighbors”
Authors: Ng Andrew Hock Soon
Published: August 2009

Literature written in the English language remains a contested terrain in Malaysia, especially amongst Malay writers who must carefully negotiate between their identities as Malays (symbiotically yoked with Islam) and as individuals living in a modern and increasingly globalized world. This essay explores the strategic compromises writers have to make when writing about sexuality, religion and identity. Its focus is on the issue of polygamy in “Mariah” by Che Husna Azhari and homosexuality and middle-class values in “Neighbors” by Karim Raslan. I argue that these writers have to deploy irony in their narratives in order to introduce taboo issues without seeming to endorse them overtly.
Evaluation of Dynamic Tensile Characteristics of Polypropylene Composites with Temperature Variation
Authors: Jin Sung Kim  , Huh Hoon , Lee Kang Wook
Published: August 2009

This article suggests two useful methods to obtain true stress—strain curves with the variation of the strain rate ranging from 0.001 to 200/s using a finite element technique and optimization for two typical polymers: a polypropylene; and a polypropylene composite. The polypropylene is adopted as a core material of a vehicle’s instrument panel and the polypropylene composite sustains the passenger-side air bag module (PAB module) as a structural member. Their dynamic tensile characteristics are important to predict deformation modes of the PAB module which undergoes high speed deformation during air bag expansion. Since the polymers are temperature sensitive materials, the dynamic tensile tests were performed at the three levels of temperature: the low temperature (—30°C); the room temperature (21°C); the high temperature (85°C). During tensile tests of two polypropylene composites, the gage region in the specimen of the polypropylene composite elongates uniformly while that of the polypropylene does not elongate uniformly. In the case of the polypropylene, experimental stress—strain curves were modified by enforcing the load response calculated by finite element analysis coincident with that of the experiment. In the case of the polypropylene composite, experimental stress—strain curves were scaled by applying change rate of the gage length. Stress—strain curves of both cases provide excellent performance in their numerical response with the finite element analysis. The material properties obtained are indispensible to estimate the high speed deformation mode during air bag expansion at both normal and harsh operating conditions.
Crystallinity Behavior of MDPE-Clay Nanocomposites Fabricated using Ball Milling Method
Authors: Abareshi M. , Zebarjad S.M. , Goharshadi E.K.
Published: August 2009

Polymer-clay nanocomposites were fabricated from medium-density polyethylene and organically modified Na-montmorillonite (MMT) using the planetary ball milling as a new method. The materials were characterized using scanning electron microscopy, transmission electron microscopy, and X-ray diffraction (XRD). The crystalline size of polyethylene (PE) filled with MMT was studied using XRD. These studies indicated that the addition of MMT decreases the crystalline size of the polymer. Moreover, the degree of crystallinity of both ball-milled and un-milled PE and PE-clay nanocomposites was measured by applying the XRD technique. The results show that both milling time and clay content decrease the degree of crystallinity of PE.
Near Infrared Measurement of Cotton Fiber Micronaire, Maturity and Fineness - a Comparative Investigation
Authors: Rodgers James , Montalvo Joseph , Davidonis Gayle , VonHoven Terri
Published: August 2009

A key cotton fiber quality property is micronaire, which acts as an indicator of the fiber’s maturity and fineness. Previous studies have demonstrated the ability of Near Infrared (NIR) instrumentation to measure these cotton properties with varying degrees of success, but these studies did not provide conclusions on the capabilities of NIR spectroscopy as a general technique for these analyses. Recent advances in NIR technology could result in improved measurements of these cotton properties. A comparative investigation was implemented to determine the capabilities of modern commercial bench-top and portable NIR systems to monitor cotton fiber micronaire, maturity, and fineness in order to gain insight as to the “universality” of the NIR measurements for these fiber properties. Cotton samples were analyzed on five commercial systems and an older, custom-built system. Very good spectral agreement was observed between the portable and bench-top NIR units. The rapid and simultaneous measurement of cotton micronaire, maturity, and fineness by multiple commercial systems was demonstrated and compared favorably to the custom system, but without the delay and cost in building custom units. For the bench-top NIR systems, all end-state criteria were successfully meet. The “universal” nature of the NIR measurement of these cotton fiber properties was validated for commercial NIR systems. As expected, the NIR results for the portable NIR units were normally not as good as those for the bench-top instruments, but they were very acceptable for demonstrating the potential for the portable units to measure these cotton fiber properties.
Literary geography: reforging the connections
Authors: Saunders Angharad
Published: August 2009

This article explores the current landscape of literary geography against the backdrop of a broadened interest in geography’s textual traditions. It suggests that after a period of relative health in the mid- to late twentieth century literary geography has been seemingly lost within wider debates over textual knowledges and practices as they pattern out within the discipline’s scientific history. Drawing on work from literary studies and geography, it goes on to propose three areas where there is opportunity for a literary geography to reassert itself and contribute forcefully to geographical debates.
Impacts of alien plant invasions on species richness in Mediterranean-type ecosystems: a meta-analysis
Authors: Gaertner Mirijam , Den Breeyen Alana , Cang Hui  , Richardson David M.
Published: August 2009

Besides a general consensus regarding the negative impact of invasive alien species in the literature, only recently has the decline of native species attributable to biological invasions begun to be quantified in many parts of the world. The cause-effect relationship between the establishment and proliferation of alien species and the extinction of native species is, however, seldom demonstrated. We conducted a meta-analysis of studies in Mediterranean-type ecosystems (MTEs) to examine: (1) whether invasion of alien plant species indeed causes a reduction in the number of native plant species at different spatial and temporal scales; (2) which growth forms, habitat types and areas are most affected by invasions; and (3) which taxa are most responsible for native species richness declines. Our results confirm a significant decline in native species richness attributable to alien invasions. Studies conducted at small scales or sampled over long periods reveal stronger impacts of alien invasion than those at large spatial scales and over short periods. Alien species from regions with similar climates have much stronger impacts, with the native species richness in South Africa and Australia declining significantly more post-invasion than for European sites. Australian Acacia species in South Africa accounted for the most significant declines in native species richness. Among the different growth forms of alien plants, annual herbs, trees and creepers had the greatest impact, whereas graminoids generally caused insignificant changes to the native community. Native species richness of shrublands, old fields and dune vegetation showed significant declines, in contrast to insignificant declines for forest habitats.
Glaciohydraulic supercooling
Authors: Cook Simon J. , Knight Peter G.
Published: August 2009

In this progress report we review recent work which has investigated the process of glaciohydraulic supercooling and its significance for a range of glaciological and geological phenomena. Since our last report (Knight and Cook, 2008), glaciohydraulic supercooling has been identified in new locations and under hitherto unrecognized conditions, both for modern and formerly glaciated environments. Recent work has examined the record of supercooling preserved in the landform and sediment record, within tunnel valleys and in sequences of melt-out till. We suggest that supercooling may also have important implications for glacier dynamics because of the role it may play in controlling the geometry of subglacial overdeepenings, which in turn acts as a control on the dynamics of tidewater glaciers. Despite these numerous recent scientific advances, there remains a need to critically evaluate the importance of supercooling for the various aspects of sediment entrainment and flux, glacial geomorphology and ice dynamics with which it has become associated. We illustrate how collaboration with researchers in other branches of cryospheric science, such as sea-ice scientists, might shed new light on the significance of supercooling within these various aspects of glacier science.
Poly(vinyl chloride) film filled with microcrystalline cellulose prepared from cotton fabric waste: properties and biodegradability study
Authors: Chuayjuljit Saowaroj , Su-uthai Siriwan , Charuchinda Sireerat
Published: August 2009

Hydrolysis of cotton fabric waste to produce microcrystalline cellulose (MCC) was carried out using 2.5 N hydrochloric acid at 100°C for 30 min. Characterization of the structure, morphology, particle size as well as the thermal decomposition of the obtained MCC were studied using X-ray diffractometer, scanning electron microscope and laser light scattering particle size analyzer and thermogravimetric analyzer, respectively. These results indicated that the obtained MCC had a fibrous structure of a 40 µm average particle size and possessed a form of highly native crystalline cellulose I. In addition, its maximum degradation temperature was observed at 350°C. The poly(vinyl chloride) (PVC) films in this work were produced by first blending the produced MCC with PVC resin in amounts of 5—30 parts per hundred of resin. The blends were then made into film using a two-roll mill. The tensile properties of the film were measured using a Universal Testing Machine. The biodegradation tests were carried out in soil and in a moisture-controlled chamber. The biodegradability was estimated by the loss of mass, moisture absorption capacity and electron microscope studies. It was found that the tensile strength and Young’s modulus of the blends increased with increasing amounts of MCC. Similarly, moisture absorption and biodegradability of the films were also increased as the amount of MCC increased. The results implied that MCC behaved not only as a reinforcing filler but also as a biodegradability promoter of PVC films.
Characterization of residues from physicochemical treatment of waste fluorescent lamps
Authors: Urniezaite Inga , Denafas Gintaras , Jankunaite Dalia
Published: August 2009

Fluorescent lamps are widely used world-wide due to their long life and energy saving capability. These lamps contain mercury (Hg) as a source of fluorescent radiation. The object of this study is a new technology for physicochemical treatment of waste fluorescent lamps. The residuals of the technological process were evaluated for potential leaching of heavy metals into the environment. Evaluation was performed using standardized extraction tests. Additionally, X-ray diffractometry (XRD) analysis, as well as tests with complex-forming agents and under pH-stable conditions were performed aiming to predict stability of the residuals in various environmental conditions. According to the XRD analysis, the minerals fluorapatite and hydroxylapatite were dominant in analyzed samples. The results of total extraction by aqua regia revealed that residuals contain relatively high total concentrations of Hg, Mn, and Zn. Concentrations of heavy metals, leaching to aqueous solution, were compared to leaching limit values (according to EU legislation). The concentrations of available Hg in the waste fluorescent lamp treatment products, according to its solubility in the water, exceed the limit values. The measured water-leachable Hg concentration was 4.88 mg kg-1, while the value for waste acceptable at hazardous waste landfill sites is 2 mg kg-1. Concentrations of other measured heavy metals did not exceed the limit values. According to the results, Hg stabilization potential for presented technology exceeds 99%.