bluuebunny/crossref_metadata_2025 huggingface dataset:
COSMOLOGY OF "VISIBLE" STERILE NEUTRINOS
Authors: GELMINI GRACIELA B.
Published: September 2005

We point out that in scenarios with a low reheating temperature TR << 100 MeV at the end of (the last episode of) inflation or entropy production, the abundance of sterile neutrinos becomes largely independent of their coupling to active neutrinos. Thus, cosmological bounds become less stringent than usually assumed, allowing sterile neutrinos to be "visible" in future experiments. For example, the sterile neutrino required by the LSND result does not have any cosmological problem within these scenarios.
INFLATION: WHERE DO WE STAND?
Authors: MARTIN JÉRÔME
Published: September 2005

In this short review, the predictions of inflation are presented and compared to the most recent measurements of the Cosmic Microwave Background (CMB) anisotropy. It is argued that inflation is compatible with these observations but that these ones are not yet accurate enough to probe the details of the scenario.
LOGIC DESIGN OF ORTHOGONAL VARIABLE SPREADING FACTOR CODE GENERATOR
Authors: LEE DONG-HAHK
Published: September 2005

This letter presents a new architecture for othogonal variable spreading factor (OVSF) code generator. The basic idea of the proposed method is to generate the code sequence using the outputs of binary counter and the binary representation of the code number. The proposed architecture can generate the code sequences as adding the only combinational logic circuits without an additional counter, if other code sequences are required according to SFs. Since the proposed generator is applied to W-CDMA modem that used different SFs simultaneously, it contributes to the reduction of the modem hardware complexity.
NOVEL DISCRIMINATIVE VECTOR QUANTIZATION APPROACH FOR SPEAKER IDENTIFICATION
Authors: ZHOU GUANGYU , MIKHAEL WASFY B. , MYERS BRENT
Published: September 2005

A novel Discriminative Vector Quantization method for Speaker Identification (DVQSI) is proposed, and its parameters selection is discussed. In the training mode of this approach, the vector space of speech features is divided into a number of regions. Then, a Vector Quantization (VQ) codebook for each speaker in each region is constructed. For every possible combination of speaker pairs, a discriminative weight is assigned for each region, based on the region's ability to discriminate between the speaker pair. Consequently, the region, which contains a larger distribution difference between the speech feature vector sets of the two speakers in the speaker pair, plays a more important role by assigning it a larger discriminative weight, in identifying the better speaker match from the two speakers. In the testing mode, to identify an unknown speaker, discriminative weighted average VQ distortion pairs are computed for the unknown speaker input waveform. Then, a technique is described that figures out the best match between the unknown waveform and speakers' templates. The proposed DVQSI approach can be considered a generalization of the existing VQ technique for Speaker Identification (VQSI). The method presented here yields better Speaker Identification (SI) accuracy by employing the discriminative weights and space segmentation as design parameters. This is confirmed experimentally. In addition, a computationally efficient implementation of the DVQSI technique is given which uses a tree-structured-like approach to obtain the codebooks.
COMPONENT TOLERANCE ANALYSIS OF A PARALLEL RESONANT MAGNET EXCITATION SCHEME FOR RAPID CYCLING SYNCHROTRON USING PSpice
Authors: BORAGE MANGESH , TIWARI SUNIL , KOTAIAH SWARNA
Published: September 2005

The parallel resonant scheme used to excite the magnets is characterized with high quality factor. The characteristic steep slope of the network gain near the resonant frequency makes the performance susceptible to the changes in component values. To accommodate the effect of varying component values, appropriate amplitude and phase over-drive capabilities in the ac source are required to maintain the magnet current of desired amplitude and in desired phase. A method of analysis of component tolerances using general purpose circuit simulation software, PSpice, is proposed in this letter. Using proposed normalized circuit description of the parallel resonant scheme, worst-case combination of component tolerances is determined. The evaluation of the effect of component tolerances in terms of required magnitude and phase over-drive of the ac source is presented under illustrative circuit conditions. Effect of various parameters on the over-drive is examined.
A NOVEL STATE ENCODING ALGORITHM FOR LOW POWER IMPLEMENTATION
Authors: CHEN CHUNHONG , ZHAO JIANG , AHMADI MAJID
Published: September 2005

State encoding problem assigns binary codes to given symbolic states such that a specific objective function such as power dissipation can be optimized in the final implementation. In this paper, we present a novel encoding technique to minimize the switching activity of any given FSMs for low power design. The experiments with standard benchmarks show that the proposed algorithm is a significant improvement over previous ones.
A SPLIT L2 DATA CACHE FOR SCALABLE CC-NUMA MULTIPROCESSORS
Authors: CHUNG SUNG WOO , KIM HYONG-SHIK , JHON CHU SHIK
Published: September 2005

In scalable CC-NUMA multiprocessors, it is crucial to reduce the average memory access time. For applications where the second-level (L2) cache is large enough, we propose a split L2 cache to utilize the surplus space. The split L2 cache is composed of a traditional LRU cache and an RVC (Remote Victim Cache) which only stores the data of remote memory address range. Thus, it reduces the average L2 cache miss time by keeping remote blocks that would be discarded otherwise. Though the split cache does not reduce the miss rates, it is observed to reduce the total execution time effectively by up to 27%.It even outperform an LRU cache of double size.
ANALYSIS OF THE TRANSFORM DOMAIN LMS ALGORITHM WITH INSUFFICIENT LENGTH ADAPTIVE FILTER
Authors: MAYYAS K.
Published: September 2005

Though, in most practical applications, the length of the adaptive filter is less than that of the unknown system impulse response, analysis of adaptive filtering algorithms almost always assumed a sufficient length adaptive filter whose length is equal to that of unknown system. Theoretical results on the sufficient length adaptive algorithm do not necessarily apply to the realistic insufficient length case and, therefore, it becomes extremely desirable for practical purposes that we quantify the statistical behavior of the insufficient length adaptive algorithm. In this paper, we analyze the popular Transform Domain LMS (TDLMS) algorithm with insufficient length adaptive filter for Gaussian input data and using the common independence assumption. Analysis yields exact theoretical expressions that describe the mean and mean-square convergence of the algorithm, which lead to a better understanding to the performance properties of the insufficient length TDLMS adaptive algorithm. Simulation experiments illustrate the accuracy of the theoretical results in predicting the convergence behavior of the algorithm.
AN ACCURATE AND MATCHING-FREE THRESHOLD-VOLTAGE MEASUREMENT SYSTEM FOR FLOATING-GATE MOS TRANSISTORS
Authors: HOU AN SANG
Published: September 2005

Due to its programmable threshold-voltage characteristic, the floating-gate MOS transistor (FGT) plays an important role in the low-power applications. To tune the threshold voltages of FGTs accurately, a real-time system is presented to measure the threshold voltages. The system includes decoders, analog multiplexers, threshold-voltage measurement block, A/D converter and 32-bit advanced RISC machine (ARM). The feedback technique is applied so that the threshold voltages of FGTs can be measured with high accuracy. The measurement error lies in the range of ±0.3% with 16-bit A/D converter, and there has no constraint on the choice of capacitances between floating-gate and control-gate. The proposed measurement system does not require any matched component. The mathematical models of threshold-voltage measurement block are also presented. Thus, the accuracy of threshold-voltage measurements can be verified with these models.
A UNIQUE INDUCTION HEATED COOKING APPLIANCES RANGE USING HYBRID RESONANT CONVERTER
Authors: SADHU PRADIP KUMAR , JANA NARENDRANATH , CHAKRABARTI RUPENDRANATH , MITTRA DILIP KUMAR
Published: September 2005

The present paper describes a converter where both series and parallel resonant circuits are used. In order to minimize losses, switching is made at zero current crossover (ZCS). The converter described in this paper has four MOS-controlled thyristor (MCTs) in H-bridge configuration (Full bridge). It is used for an induction cooking-range with two hot zones. The switching frequency is 50 kHz. To optimize the system efficiency, different control strategies are discussed.
PHYSICAL LAYER OF A BASE-BAND OFDM MODEM: ALGORITHMS AND PERFORMANCE
Authors: PNEVMATIKAKIS ARISTODEMOS , BLIONAS SPYROS , TRIANTIS DIMITRIS
Published: September 2005

The base-band section of a modem employing Orthogonal Frequency Division Multiplexing (OFDM) is described in this paper. It utilizes the necessary algorithms to combat distortion due to the channel conditions and imperfect synchronization. A model describing these distortions is used to derive the algorithms. The system is realized in a prototype platform for the HIPERLAN/2 standard, but modifications for compliance to other broadband digital broadcasting and wireless networking OFDM systems are proposed. The performance of the prototype base-band modem is described.
COMPARISON OF SIGMA–DELTA CONVERTER CIRCUIT ARCHITECTURES IN DIGITAL CMOS TECHNOLOGY
Authors: DOLEV NOAM , KORNFELD AVNER , KOLODNY AVINOAM
Published: September 2005

Integration of analog-to-digital signal conversion circuits into digital submicron silicon chips is required for many applications. This is typically implemented by sigma–delta circuits, which can provide good resolution without requiring trimming of component values. This paper presents an analytical comparison of noise performance in four alternative sigma–delta circuit configurations which have been presented in the literature, consisting of discrete-time and continuous-time integration in voltage-mode and in current-mode. For high resolution, superiority of switched-capacitor circuits over the alternatives is shown, based on process technology considerations. Design guidelines are outlined for selecting oversampling rate and other key parameters, in order to obtain maximal data resolution.
PIPELINED ARCHITECTURES FOR TRANSFORM DOMAIN LMS ADAPTIVE FILTERING
Authors: GLENTIS GEORGE-OTHON
Published: September 2005

In this paper, efficient pipelined architectures for the implementation of the Transform Domain LMS (TD-LMS) adaptive filter are considered. Pipelining of the TD-LMS algorithm is achieved by introducing an amount of time delay into the original adaptive scheme. The resulting algorithm, called thereafter the delayed TD-LMS, performs adaptive filtering with delayed coefficients adaptation. A statistical performance analysis of the proposed delayed TD-LMS adaptive algorithm is presented, both for the mean error and the mean squared error of the filter coefficients. A closed form expression is derived for the estimation of the steady state excess mean squared error, in terms of the adaptation delay and the input signal characteristics. The adaptation delay introduced to the delayed TD-LMS algorithm is subsequently utilized for the development of pipelined architectures. By retiming the delays existing in the error signal feedback loop, efficient pipelined implementations of the delayed TD-LMS algorithm are developed. The proposed architectures are suitable for parallel implementation on a general-purpose parallel machine, or on dedicated hardware, integrated on ASIC or ASIP VLSI processors.
SYMBOLIC REACHABILITY ANALYSIS FOR MULTIPLE-CLOCK SYSTEM DESIGN
Authors: YI JU-HWAN , KYUNG CHONG-MIN
Published: September 2005

This paper proposes a symbolic reachability analysis method for multiple-clock system design, which is the first approach to deal with both synchronization problems caused by metastability and rate mismatch problems caused by clock frequency mismatches in a single framework. Three methods are described to reproduce problems that occur with multiple-clock system design during reachability analysis: (1) alternate evaluation for a system with two clocks as the base-line model, (2) nondeterministic delayed evaluation to reproduce a synchronization problem, and (3) double evaluation to reproduce a clock frequency mismatch. Experimental results on ISCAS 89 benchmark show an improvement factor of average CPU time as compared to Clarke's method by 1.29, 55.41, 2.19 and 45.23 times when alternate evaluation, double evaluation, alternate evaluation with NDDE and double evaluation with NDDE is applied, respectively.
MEASURING THE MEMORY PARAMETER ON SEVERAL TRANSFORMATIONS OF ASSET RETURNS
Authors: GIL-ALANA L. A.
Published: September 2005

The issue in this paper is to measure the memory parameter in several transformations of historical data of asset returns in the UK (xt) by means of fractionally integrated techniques. We use both parametric and semiparametric methods, and the results show that the power transformations of the absolute values of the returns (i.e., |xt|θ, with θ < 2 to avoid the fourth moment problem) are long memory, with the memory parameter fluctuating around 0.25.
FINANCIAL MARKET MODEL WITH INFLUENTIAL INFORMED INVESTORS
Authors: GRORUD AXEL , PONTIER MONIQUE
Published: September 2005

We develop a financial model with an "influential informed" investor who has an additional information and influences asset prices by means of his strategy. The prices dynamics are supposed to be driven by a Brownian motion, the informed investor's strategies affect the risky asset trends and the interest rate. Our paper could be seen as an extension of Cuoco and Cvitanic's work [4] since, as these authors, we solve the informed influential investor's optimization problem. But our main result is the construction of statistical tests to detect if, observing asset prices and agent's strategies, this influential agent is or not an informed trader.
MAXIMIZING THE PROBABILITY OF A PERFECT HEDGE USING AN IMPERFECTLY CORRELATED INSTRUMENT
Authors: HOBSON DAVID , PENN JEREMY
Published: September 2005

Let Xϕ denote the trading wealth generated using a strategy ϕ, and let CT be a contingent claim which is not spanned by the traded assets. Consider the problem of finding the strategy which maximizes the probability of terminal wealth meeting or exceeding the claim value at some fixed time horizon, i.e., of finding [Formula: see text]. This problem is sometimes referred to as the quantile hedging problem.

We consider the quantile hedging problem when the traded asset and the contingent claim are correlated geometric Brownian motions. This fits with several important examples. One of the benefits of working with such a concrete model is that although it is incomplete we can still do calculations. In particular, we can consider some detailed issues such as the impact of the timing at which information about CT is revealed.
PARTIAL INFORMATION AND HAZARD PROCESS
Authors: JEANBLANC MONIQUE , VALCHEV STOYAN
Published: September 2005

This paper studies in some examples the role of information in a default-risk framework. We examine three types of information for a firm's unlevered asset value to the secondary bond market: the classical case of continuous and perfect information, observation of past and contemporaneous asset values at selected discrete times, and observation of contemporaneous asset value at discrete times. The third information filtration is contained in the second, which in turn, is contained in the first. We investigate the changes of the distributional properties of the default time and the properties of bond prices and credit spreads with the reductions of the information sets. Consistently with the observed market prices, model bond prices with partial information have surprise jumps prior to default. Credit spreads for very short times to maturities are increasing with the reductions of the information sets. High-yield bonds with the two types of incomplete information have downward sloping term structures of credit spreads. For firms with good credit qualities, increases of the observation lags lead to upward shifts in the term structures of credit spreads. The two information constrained models admit reduced form representations, in which the time of default is a totally inaccessible time with default arrival intensities, but it is better avoiding the intensity approach to valuation since the hazard process approach is more efficient.
AN ALTERNATIVE INTEREST RATE TERM STRUCTURE MODEL
Authors: PLATEN ECKHARD
Published: September 2005

This paper proposes an alternative approach to the modeling of the interest rate term structure. It suggests that the total market price for risk is an important factor that has to be modeled carefully. The growth optimal portfolio, which is characterized by this factor, is used as reference unit or benchmark for obtaining a consistent price system. Benchmarked derivative prices are taken as conditional expectations of future benchmarked prices under the real world probability measure. The inverse of the squared total market price for risk is modeled as a square root process and shown to influence the medium and long term forward rates. With constant parameters and constant short rate the model already generates a hump shaped mean for the forward rate curve and other empirical features typically observed.
A MERTON-MODEL APPROACH TO ASSESSING THE DEFAULT RISK OF UK PUBLIC COMPANIES
Authors: TUDELA M. , YOUNG G.
Published: September 2005

This paper shows how a Merton-model approach can be used to develop measures of the probability of failure of individual quoted UK companies. Probability estimates are then constructed for a group of failed companies and their properties as leading indicators of failure assessed. Probability estimates of failure for a control group of surviving companies are also constructed. These are used in probit regressions to evaluate the information content of the Merton-based estimates relative to information available in company accounts and in assessing Type I and Type II errors. We also look at power curves and accuracy ratios. The paper shows that there is much useful information in the Merton-style estimates.
PARAMETER ESTIMATION FOR A REGIME-SWITCHING MEAN-REVERTING MODEL WITH JUMPS
Authors: WU PING , ELLIOTT ROBERT J.
Published: September 2005

In this paper we propose a type of mean reverting model with jumps, where the mean reverting level changes according to a continuous time, finite state Markov chain. This model could be applied to the interest rate and energy markets. We apply filtering techniques and obtain finite dimensional filters for the unobservable state of the Markov chain based on observations of the mean reverting diffusion. Various auxiliary filters are developed that allow us to estimate the parameters of the Markov chain by the EM algorithm. A simulation study is done for a concrete example.
Endogenous adenosine protects preconditioned heart during early minutes of reperfusion by activating Akt
Authors: Solenkova Nataliya V. , Solodushko Viktoriya , Cohen Michael V. , Downey James M.
Published: September 2005

Ischemic preconditioning (IPC) is thought to protect by activating survival kinases during reperfusion. We tested whether binding of adenosine receptors is also required during reperfusion and, if so, how long these receptors must be populated. Isolated rabbit hearts were subjected to 30 min of regional ischemia and 2 h of reperfusion. IPC reduced infarct size from 32.1 ± 4.6% of the risk zone in control hearts to 7.3 ± 3.6%. IPC protection was blocked by a 20-min pulse of the nonselective adenosine receptor blocker 8-( p-sulfophenyl)-theophylline when started either 5 min before or 10 min after the onset of reperfusion but not when started after 30 min of reperfusion. Protection was also blocked by either 8-cyclopentyl-1,3-dipropylxanthine, an adenosine A1-selective receptor antagonist, or MRS1754, an A2B-selective antagonist, but not by 8-(3-chlorostyryl)caffeine, an A2A-selective antagonist. Blockade of phosphatidylinositol 3-OH kinase (PI3K) with a 20-min pulse of wortmannin also aborted protection when started either 5 min before or 10 or 30 min after the onset of reperfusion but failed when started after 60 min of reflow. U-0126, an antagonist of MEK1/2 and therefore of ERK1/2, blocked protection when started 5 min before reperfusion but not when started after only 10 min of reperfusion. These studies reveal that A1 and/or A2B receptors initiate the protective signal transduction cascade during reperfusion. Although PI3K activity must continue long into the reperfusion phase, adenosine receptor occupancy is no longer needed by 30 min of reperfusion, and ERK activity is only required in the first few minutes of reperfusion.
IGF-I stimulates protein synthesis in skeletal muscle through multiple signaling pathways during sepsis
Authors: Vary Thomas C.
Published: September 2005

Chronic septic abscess formation causes an inhibition of protein synthesis in gastrocnemius not observed in rats with a sterile abscess. Inhibition is associated with an impaired mRNA translation initiation that can be ameliorated by elevating IGF-I but not insulin. The present study investigated the ability of IGF-I signaling to stimulate protein synthesis in gastrocnemius by accelerating mRNA translation initiation. Experiments were performed in perfused hindlimb preparations from rats 5 days after induction of a septic abscess. Protein synthesis in gastrocnemius from septic rats was accelerated twofold by the addition of IGF-I (10 nM) to perfusate. IGF-I increased the phosphorylation of translation repressor 4E-binding protein-1 (4E-BP1). Hyperphosphorylation of 4E-BP1 in response to IGF-I resulted in its dissociation from the inactive eukaryotic initiation factor (eIF) 4E·4E-BP1 complex. Assembly of the active eIF4F complex (as assessed by the association eIF4G with eIF4E) was increased twofold by IGF-I in the perfusate. In addition, phosphorylation of eIF4G and ribosomal protein S6 kinase-1 (S6K1) was also enhanced by IGF-I. Activation of mammalian target of rapamycin, an upstream kinase implicated in phosphorylating both 4E-BP1 and S6K1, was also observed. Thus the ability of IGF-I to accelerate protein synthesis during sepsis may be related to a stimulation of signaling to multiple steps in translation initiation with an ensuing increased phosphorylation of eIF4G, eIF4E availability, and S6K1 phosphorylation.
Quantitation of mitral annular oscillations and longitudinal “ringing” of the left ventricle: a new window into longitudinal diastolic function
Authors: Riordan Matt M. , Kovács Sándor J.
Published: September 2005

For diastolic function (DF) quantification, transmitral flow velocity has been characterized in terms of the geometric features of a triangle (heights, widths, areas, durations) approximating the E-wave contour, whereas mitral annular velocity has only been characterized by E′-wave peak amplitude. The fact that E-waves convey global DF information, whereas annular E′-waves provide longitudinal DF information, has not been fully characterized, nor has the physiological legitimacy of combining fluid motion (E)- and tissue motion (E′)-derived measurements into routinely used indexes (E/E′) been fully elucidated. To place these Doppler echo measurements on a firmer causal, physiological, and clinical basis, we examined features of the E′-wave (and annular motion in general), including timing, amplitude, duration, and contour (shape), in kinematic terms. We derive longitudinal rather than global indexes of stiffness and relaxation of the left ventricle and explain the observed difference between E- and E′-wave durations. On the basis of the close agreement between model prediction and E′-wave contour for subjects having normal physiology, we propose damped harmonic oscillation as the proper paradigm in which to view and analyze the motion of the mitral annulus during early filling. Novel, longitudinal indexes of left ventricular stiffness, relaxation, viscosity, and stored (end-systolic) elastic strain can be determined from the E′-wave (and any subsequent waves) by modeling annular motion during early filling as damped harmonic oscillation. A subgroup exploratory analysis conducted in diabetic subjects ( n = 9) and nondiabetic controls ( n = 12) indicates that longitudinal DF indexes differentiate between these groups on the basis of longitudinal damping ( P < 0.025) and longitudinal stored elastic strain ( P < 0.005).
Skin blood flow influences near-infrared spectroscopy-derived measurements of tissue oxygenation during heat stress
Authors: Davis Scott L. , Fadel Paul J. , Cui Jian , Thomas Gail D. , Crandall Craig G.
Published: September 2005

Near-infrared (NIR) spectroscopy is a noninvasive optical technique that is increasingly used to assess muscle oxygenation during exercise with the assumption that the contribution of skin blood flow to the NIR signal is minor or nonexistent. We tested this assumption in humans by monitoring forearm tissue oxygenation during selective cutaneous vasodilation induced by locally applied heat ( n = 6) or indirect whole body heating (i.e., heating subject but not area surrounding NIR probes; n = 8). Neither perturbation has been shown to cause a measurable change in muscle blood flow or metabolism. Local heating (∼41°C) caused large increases in the NIR-derived tissue oxygenation signal [before heating = 0.82 ± 0.89 optical density (OD), after heating = 18.21 ± 2.44 OD; P < 0.001]. Similarly, whole body heating (increase internal temperature 0.9°C) also caused large increases in the tissue oxygenation signal (before heating = −0.31 ± 1.47 OD, after heating = 12.48 ± 1.82 OD; P < 0.001). These increases in the tissue oxygenation signal were closely correlated with increases in skin blood flow during both local heating (mean r = 0.95 ± 0.02) and whole body heating (mean r = 0.89 ± 0.04). These data suggest that the contribution of skin blood flow to NIR measurements of tissue oxygenation can be significant, potentially confounding interpretation of the NIR-derived signal during conditions where both skin and muscle blood flows are elevated concomitantly (e.g., high-intensity and/or prolonged exercise).
Ovariectomy prevents the recovery of atrophied gastrocnemius skeletal muscle mass
Authors: Sitnick Mitchell , Foley Andrea M. , Brown Marybeth , Spangenburg Espen E.
Published: September 2005

The recovery of atrophied muscle mass in animals is thought to be dependent on a number of factors including hormones, cytokines, and/or growth factor expression. The Akt/mammalian target of rapamycin (mTOR) signaling pathway is believed to be activated by these various factors, resulting in skeletal muscle growth through the initiation of protein synthesis. It was hypothesized that surgical removal of the ovaries (Ovx) may alter activation of the Akt/mTOR signaling pathway, a mechanism necessary for muscle regrowth. To test this, 36 Sprague-Dawley rats underwent Ovx or sham surgeries. A portion of the animals were then subjected to hindlimb unloading (HLU) for 28 days. After HLU, one group of Sham and Ovx rats underwent a 14-day recovery period in which the animals were allowed free cage ambulation. The HLU animals demonstrated ∼21–27% reduction in medial gastrocnemius muscle mass irrespective of whether the ovaries were intact or not. The Sham animals that were reloaded recovered their atrophied muscle mass; however, the Ovx group failed to recover any of the atrophied muscle mass with reloading. The failure to recover muscle mass in the Ovx group was associated with reduced phosphorylation levels of both Akt and p70s6k, whereas in the Sham recovery animals no reductions were found in Akt phosphorylation and significant increases in p70s6k activation were detected. Finally, no differences were detected in mTOR phosphorylation in any of Sham or Ovx groups. These results suggest that ovariectomy surgeries could be detrimental to the recovery of atrophied muscle mass.
The Impact of Pedigree Structure on Heritability Estimates for Pulse Pressure in Three Studies
Authors: Hsu Fang-Chi , Zaccaro Daniel J. , Lange Leslie A. , Arnett Donna K. , Langefeld Carl D. , Wagenknecht Lynne E. , Herrington David M. , Beck Stephanie R. , Freedman Barry I. , Bowden Donald W. , Rich Stephen S.
Published: September 2005

Objectives: Pulse pressure (PP) is a measure of large artery stiffness and has been shown to be an important predictor of cardiovascular morbidity and mortality. The aims of the present study were to investigate the heritability of PP in three studies, the Diabetes Heart Study (DHS), the Insulin Resistance Atherosclerosis Family Study (IRAS FS), and the NHLBI Family Heart Study (FHS), to estimate the residual heritability after inclusion of a common set of covariates, and to investigate the impact of pedigree structure on estimating heritability. Methods and Results: DHS is primarily a sibling pair nuclear family study design, while both IRAS FS and FHS have large pedigrees. Heritability estimates of log-transformed PP were obtained using variance component models. After adjusting for age, gender, ethnicity/center, height, diabetes status, and mean arterial pressure (MAP), heritability estimates of PP were 0.40 ± 0.08 , 0.22 ± 0.05, and 0.19 ± 0.03 in DHS, IRAS FS, and FHS, respectively. The heritability estimate from DHS was significantly different from both IRAS FS and FHS (both p values <0.05). A random re-sampling technique (modified bootstrap) was used to explore the heritability in the IRAS FS and FHS data when these pedigrees were trimmed to mimic the DHS pedigree structure. The re-sampling method (mimicking a sibling pair nuclear family design in all studies) yielded PP heritability estimates of 0.37, 0.34, and 0.27 in DHS, IRAS FS, and FHS, respectively. There was no significant difference among the heritability estimates from the three studies based on the re-sampling method. Conclusion: We have shown that PP has a moderately heritable component in three different studies. These data illustrate the influence of pedigree structure can have on estimating heritability. Thoughtful comparisons of heritability estimates must consider study design factors such as pedigree structure.
Differential Global Gene Expression Response Patterns of Human Endothelium Exposed to Shear Stress and Intraluminal Pressure
Authors: Andersson Maria , Karlsson Lena , Svensson Per-Arne , Ulfhammer Erik , Ekman Mikael , Jernås Margareta , Carlsson Lena M.S. , Jern Sverker
Published: September 2005

We investigated the global gene expression response of endothelium exposed to shear stress and intraluminal pressure and tested the hypothesis that the two biomechanical forces induce a differential gene expression response pattern. Intact living human conduit vessels (umbilical veins) were exposed to normal or high intraluminal pressure, or to low or high shear stress in combination with a physiological level of the other force in a unique vascular ex vivo perfusion system. Gene expression profiling was performed by the Affymetrix microarray technology on endothelial cells isolated from stimulated vessels. Biomechanical forces were found to regulate a very large number of genes in the vascular endothelium. In this study, 1,825 genes were responsive to mechanical forces, which corresponds to 17% of the expressed genes. Among pressure-responsive genes, 647 genes were upregulated and 519 genes were downregulated, and of shear stress-responsive genes, 133 genes were upregulated and 771 downregulated. The fraction of genes that responded to both pressure and shear stimulation was surprisingly low, only 13% of the regulated genes. Our results indicate that the two different stimuli induce distinct gene expression response patterns, which can also be observed when studying functional groups. Considering the low number of overlapping genes, we suggest that the endothelial cells can distinguish between shear stress and pressure stimulation.
Monitoring the Penetration and Distribution of Topically Applied Formulations through the Skin in Relation to the Skin Protein/Lipid Morphological Characteristics
Authors: Garidel Patrick
Published: September 2005

The ability of topically applied dosage forms to penetrate the skin depends on the interactions of the formulation ingredients with the intrinsic components of the skin. These interactions define the penetration route as well as the distribution of the drug in the skin tissue. The present study focused on monitoring components of externally applied formulations through the skin (ex vivo) via mid-infrared microspectroscopic techniques. Infrared microspectroscopy represents a new bioanalytical method, combining the powerfulness of chemical component analysis by means of infrared spectroscopy and using the high lateral resolution (∼20 µm) as obtained from microscopy. Two methods are applied for analysing tissues: the mapping and the imaging approach. A major breakthrough using infrared microspectroscopy in tissue diagnostics was the development and implementation of so-called focal plane array detectors. Using these detectors, sample areas of about 0.25–16 mm2 can be analyzed. The highest lateral resolution obtained by the transmission techniques approaches the mid-infrared diffraction limit of approximately 6 µm. Using mid-infrared microspectroscopic imaging, a large amount of biochemical information, at high lateral resolution, is generated, not yet available by other methods. Additional advantages are: it is a non-invasive, non-destructive approach, requiring no complex and time-consuming tissue staining procedures. In the present study, mid-infrared microspectroscopic mapping and imaging techniques in transmission are used for the biochemical characterisation of skin samples (e.g. lipid/protein distribution). This information provides new insight into the morphology of the tissue constitution. Additionally, examples are presented concerning the analysis of the distribution of topically applied drugs (e.g. UV B blocker or liposomes) through the skin. The potential as well as the limits of the methods for dermatological research are discussed.
Hormone Receptor Expressions and Proliferation Markers in Postmenopausal Endometrial Polyps
Authors: Inceboz Umit Sungurtekin , Nese Nalan , Uyar Yildiz , Ozcakir H. Tayfun , Kurtul Ozgur , Baytur Yesim Bulbul , Kandiloglu Ali Riza , Caglar Husnu , Fraser Ian S.
Published: September 2005

Background/Aims: Endometrial polyps are quite common in the general population, they have a significant role in postmenopausal bleeding, and the pathogenesis is unclear. The aim of this study was to investigate proliferation markers and expression of estrogen and progesterone receptors in endometrial polyps in postmenopausal women. Methods: Endometrial polyps were removed by hysteroscopy from 36 women who presented with postmenopausal bleeding. None were using hormonal therapy. The control group consisted of 16 inactive-atrophic postmenopausal endometrial specimens removed at hysterectomy. Immunohistochemistry was used to demonstrate expression of estrogen and progesterone receptors and the cell growth and apoptosis markers, Ki67, bcl-2, c-erbB-2. Results: In both the glandular epithelium and stroma of endometrial polyps, estrogen and progesterone receptors, Ki67 and bcl-2 showed significantly more positive staining than the inactive endometrium from the control group. There was no difference in expression of c-erbB-2 between the two groups. Conclusions: Estrogen may have a role in the development of postmenopausal endometrial polyps, either by direct stimulation of localized proliferation or by stimulation of proliferation via other pathways, such as activation of Ki67 or through inhibition of apoptosis via bcl-2. c- erbB-2 is unlikely to play any role in development of these lesions.
Risk Factors Associated with the Rupture of Tubal Ectopic Pregnancy
Authors: Latchaw Gregory , Takacs Peter , Gaitan Lucia , Geren Sasha , Burzawa Jennifer
Published: September 2005

Objective: To identify risk factors that may lead to the rupture of ectopic pregnancies. Study Design: A retrospective chart review was performed on patients with ectopic pregnancies at the University of Miami/Jackson Memorial Hospital between 1/1/1995 and 3/1/2002. 738 patients were identified with ectopic pregnancies. Women with tubal rupture were compared to those without rupture. Variables analyzed were demographic data, patient-related risk factors (history of pelvic surgery, bilateral tubal ligation, history of pelvic inflammatory disease, previous ectopic pregnancy, intrauterine device use) and β-human chorionic gonadotropin (βhCG) measurement. Results: There were 439 (59%) cases with a ruptured and 299 (41%) cases with an unruptured ectopic pregnancy. Multivariate logistic regression analysis revealed that previous ectopic pregnancy (OR 2.88; 95% CI 1.92, 4.33) and βhCG level ≧5,000 mIU/ml (OR 1.85; 95% CI 1.12, 3.06) were the only significant risk factors for tubal rupture. Conclusion: Patients with βhCG levels ≧5,000 mIU/ml and patients with a history of a previous ectopic pregnancy are significantly more likely to experience a tubal rupture.
Can Telemedicine Contribute to Fulfill WHO Helsingborg Declaration of Specialized Stroke Care?
Authors: Audebert Heinrich J. , Wimmer Martin L.J. , Hahn Raymund , Schenkel Johannes , Bogdahn Ulrich , Horn Markus , Haberl Roman L.
Published: September 2005

Background: Providing stroke unit treatment for all stroke patients is a cross-national goal as stated in the WHO Helsingborg Declaration. In order to achieve specialized stroke care for a large area, two stroke centers and 12 community hospitals established an integrative stroke network. This evaluation was performed to analyze achieved advances in stroke management. Methods: Core network elements are: (1) establishing stroke wards in all hospitals; (2) continuous training in stroke treatment; (3) telemedicine service staffed by a 24 h/day ‘strokologist’ with capability for high-speed videoconferencing and transfer of CT/MRI images. Data were prospectively documented in the databank of the telestroke service, in the Bavarian Stroke Registry and in the controlling departments. Results: In 2003, 4,179 stroke patients were admitted to the regional network hospitals. Between February 2003 and January 2004 a total of 2,182 teleconsultations were conducted. 250 teleconsultations yielded a nonvascular diagnosis. Indicators for stroke management quality improved compared with other hospitals without stroke unit: the frequency of CT/MRI within 3 h was 59% compared to 46%, frequency of speech therapy 36% (21%), and of occupational therapy 38% (12%). Eighty-six (2.1%) of the patients received systemic thrombolysis compared to 10 patients in the preceding year. Mean length of in-hospital stay decreased from 12.4 in 2002 to 9.7 days in 2003. Conclusions: This stroke network concept leads to a substantial improvement of stroke management. Telemedicine contributes to an early etiological assessment and fills the gap of specialized stroke expertise in neurologically underserved areas.
C-Reactive Protein Predicts Death in Patients with Non-Ischemic Cardiomyopathy
Authors: Ronnow Brianna S. , Reyna Sandra P. , Muhlestein Joseph B. , Horne Benjamin D. , Allen Maycock Chloe A. , Bair Tami L. , Carlquist John F. , Kfoury Abdallah G. , Anderson Jeffrey L. , Renlund Dale G.
Published: September 2005

C-reactive protein (CRP) has been associated with atherosclerotic complications, and we hypothesized that CRP levels might also predict death in non-ischemic patients with left ventricular dysfunction. Two hundred and three patients with non-ischemic left ventricular dysfunction undergoing cardiac catheterization were included and were followed for 2.4 ± 1.4 years to determine the incidence of fatal events. Death occurred in 15% of patients with low CRP (1st and 2nd tertiles) and 30% of patients with high CRP (3rd tertile). After adjustment for 11 covariates, high CRP (p = 0.037, hazard ratio = 2.0) significantly and independently predicted mortality. Even in the absence of coronary artery disease, patients with left ventricular dysfunction are at increased risk of mortality based on their baseline CRP concentrations.
Neonatal Persistent Pulmonary Hypertension Treated with Milrinone: Four Case Reports
Authors: Bassler Dirk , Choong Karen , McNamara Patrick , Kirpalani Haresh
Published: September 2005

Current standard therapy forpersistent pulmonary hypertension of the newborn (PPHN) consists of optimal lung inflation, hemodynamic support and selective vasodilation with inhaled nitric oxide (iNO). However, not all infants will respond. Milrinone, a phosphodiesterase (PDE) III inhibitor, is routinely used in pediatric cardiac intensive care units to improve inotropy and reduce afterload. Although its use in post-operative cardiac failure has been proven in a randomized trial, it has not been reported to be beneficial in PPHN. We report four cases with severe PPHN treated with a combination of iNO and Milrinone. All four cases were unresponsive to therapy including iNO, with a mean oxygenation index (OI) of 40 (standard deviation (SD) 12)) before Milrinone. Substantial improvement in OI (mean of 28; SD 16) was followed by extubation and survival. However, of 4 patients, 2 developed serious intraventricular hemorrhages (IVHs), and 1 had a small IVH. To clarify the risk benefit ratio, of death versus survival with impairment, a randomized controlled trial is needed.
Limbs Anthropometry of Singleton Chinese Newborns of 28–42 Weeks’ Gestation
Authors: Fok T.F. , Hon K.L. , Ng P.C. , Wong E. , So H.K. , Lau J. , Chow C.B. , Lee W.H.
Published: September 2005

Abnormalities of limbs are important features of some syndromes recognizable at birth. The purpose of this study was to establish normal standards of limbs including arm length, arm circumference, upper arm length, lower arm length, leg length, thigh circumference, upper leg length, and lower leg length. 10,226 infants (5,422 males, 4,804 females) with gestation 28–42 weeks from 12 hospitals were included. The LMS method using maximum penalized likelihood was used to perform model fitting of the anthropometric centiles for these parameters. This study provided the first set of references for the limbs of the infants by gestation and gender. Racial differences were found when comparing with other populations. The parameters are useful for evaluation of morphologic disorders involving the limbs.
Purine and Pyrimidine Metabolism and Electrocortical Brain Activity during Hypotension in Near-Term Lambs
Authors: van Os Sandra , de Abreu Ronney , Hopman Jeroen , Wethly Karina , van de Bor Margot
Published: September 2005

Background: Insufficient cerebral O2 supply leads to cellular energy failure and loss of brain cell function. The relationship between the severity of cellular energy failure due to hemorrhagic hypotension and the loss of electrocortical brain activity (ECBA), as a measure of brain cell function, is not yet fully elucidated in near-term born lambs. Objectives: To study the relationship between cerebral purine and pyrimidine metabolism, as a measure of brain cell energy failure, and brain cell function after hemorrhagic hypotension in near-term born lambs. Methods: Eight near-term lambs (term 147 days) were delivered at 131 days of gestation. After a stabilization period, mean arterial blood pressure was reduced till 30% of baseline by withdrawal of blood. Cerebrospinal fluid (CSF) was obtained at the end of the hypotensive period (2.5 h). CSF from 8 siblings was used for comparison. HPLC was used to determine purine and pyrimidine metabolites in CSF, as a measure of cellular energy failure. ECBA was calculated as the root mean square value of a band-filtered (2–16 Hz) one-channel EEG. Results: Values of guanosine, inosine, hypoxanthine, xanthine and uridine were significantly higher, while ECBA was significantly lower after hemorrhagic hypotension than control values. The concentrations of inosine, hypoxanthine, xanthine and uridine were significantly negatively linearly related to ECBA. Conclusions: Brain cell function is negatively related to concentrations of inosine, hypoxanthine, xanthine and uridine in the CSF after hemorrhagic hypotension in near-term born lambs.
Effects of Volume-Targeted Synchronized Intermittent Mandatory Ventilation on Spontaneous Episodes of Hypoxemia in Preterm Infants
Authors: Polimeni Valentina , Claure Nelson , D’Ugard Carmen , Bancalari Eduardo
Published: September 2005

Background: Hypoxemic episodes in ventilated preterm infants are frequently caused by reduced ventilation due to a decrease in lung volume and acute worsening of respiratory mechanics. Objective: To compare the efficacy of conventional time-cycled, pressure-limited flow synchronized intermittent mandatory ventilation (SIMV) and volume-targeted SIMV (VT-SIMV) in reducing the frequency and severity of these episodes. Methods: SIMV and VT-SIMV were compared in preterm infants with frequent spontaneous episodes of hypoxemia. VT-SIMV was provided with the Draeger Babylog 8000plus ventilator in volume-guarantee mode. Results: In all, 32 infants (birth weight 668 ± 126 g, gestational age 24.8 ± 1.1 weeks, age 37.5 ± 17.3 days) were studied during 2-hour periods of SIMV and VT-SIMV in random sequence. In an initial phase, a group of 12 infants was supported during VT-SIMV with a target tidal volume of 4.5 ml/kg (VT-SIMV 4.5). A planned interim analysis did not show differences in frequency and duration of hypoxemia between VT-SIMV 4.5 and SIMV, and the initial phase was stopped. In a second phase of the study, 20 infants were studied while supported with a target tidal volume of 6.0 ml/kg during VT-SIMV (VT-SIMV 6.0). In the second phase of the study, the frequency of the hypoxemic episodes did not change but the mean episode duration was shorter during VT-SIMV compared to SIMV. The proportion of mechanical breaths with small tidal volumes (≤3 ml/kg) was reduced during VT-SIMV 6.0 versus SIMV, while the peak inspiratory pressure and mean airway pressure were increased. Conclusion: VT-SIMV did not reduce the frequency of hypoxemic episodes, but VT-SIMV 6.0 was effective in reducing the duration of the hypoxemic episodes.