bluuebunny/crossref_metadata_2025 huggingface dataset:
TWO-PARAMETER DISCONTINUITY-INDUCED BIFURCATIONS OF LIMIT CYCLES: CLASSIFICATION AND OPEN PROBLEMS
Authors: KOWALCZYK P. , DI BERNARDO M. , CHAMPNEYS A. R. , HOGAN S. J. , HOMER M. , PIIROINEN P. T. , KUZNETSOV YU. A. , NORDMARK A.
Published: May 2006

This paper proposes a strategy for the classification of codimension-two discontinuity-induced bifurcations of limit cycles in piecewise smooth systems of ordinary differential equations. Such nonsmooth transitions (also known as C-bifurcations) occur when the cycle interacts with a discontinuity boundary of phase space in a nongeneric way, such as grazing contact. Several such codimension-one events have recently been identified, causing for example, period-adding or sudden onset of chaos. Here, the focus is on codimension-two grazings that are local in the sense that the dynamics can be fully described by an appropriate Poincaré map from a neighborhood of the grazing point (or points) of the critical cycle to itself. It is proposed that codimension-two grazing bifurcations can be divided into three distinct types: either the grazing point is degenerate, or the grazing cycle is itself degenerate (e.g. nonhyperbolic) or we have the simultaneous occurrence of two grazing events. A careful distinction is drawn between their occurrence in systems with discontinuous states, discontinuous vector fields, or that with discontinuity in some derivative of the vector field. Examples of each kind of bifurcation are presented, mostly derived from mechanical applications. For each example, where possible, principal bifurcation curves characteristic to the codimension-two scenario are presented and general features of the dynamics discussed. Many avenues for future research are opened.
BASIN FRACTALIZATIONS GENERATED BY A TWO-DIMENSIONAL FAMILY OF (Z1–Z3–Z1) MAPS
Authors: BISCHI GIAN-ITALO , GARDINI LAURA , MIRA CHRISTIAN
Published: May 2006

Two-dimensional (Z1–Z3–Z1) maps are such that the plane is divided into three unbounded open regions: a region Z3, whose points generate three real rank-one preimages, bordered by two regions Z1, whose points generate only one real rank-one preimage. This paper is essentially devoted to the study of the structures, and the global bifurcations, of the basins of attraction generated by such maps. In particular, the cases of fractal structure of such basins are considered. For the class of maps considered in this paper, a large variety of dynamic situations is shown, and the bifurcations leading to their occurrence are explained.
GENERAL CONSIDERATION FOR MODELING AND BIFURCATION ANALYSIS OF SWITCHED DYNAMICAL SYSTEMS
Authors: MA YUE , KAWAKAMI HIROSHI , TSE CHI K. , KOUSAKA TAKUJI
Published: May 2006

In much of the previous study of switched dynamical systems, it has been assumed that switching occurs at a common border between two regions in the same space as the system trajectory crosses the border. However, models arising from this consideration cannot cover systems whose trajectories do not actually "cross" the border. A typical example is the current-mode controlled boost converter whose trajectory is "reflected" at the border. In this paper, we propose a general method to model switched dynamical systems. Also, we suggest an analytical procedure to determine periodic solutions and their stability. The method is developed in terms of solution flows, and no solution has to be explicitly written. Most practical switched dynamical systems can be modeled and analyzed by this method.
CONTROL OF A CHAOTIC SWITCHED ARRIVAL SYSTEM WITH CONTROLLED INTERNAL CONNECTIONS
Authors: LI WEI , USHIO TOSHIMITSU
Published: May 2006

In this paper, a chaotic switched arrival system with N buffers and controlled internal connections is considered. An unstable N periodic orbit embedded in the chaotic attractor is theoretically derived. A novel method for the stabilization of the unstable N periodic orbit using the flow rates of the internal connections as control variables is presented. It is showed that the switched arrival system can be stabilized by using N - 2 internal connections. Numerical simulation results are also provided to demonstrate the theoretical analysis.
CURRENT-FEEDBACK OPERATIONAL AMPLIFIER-BASED INDUCTORLESS MIXED-MODE CHUA'S CIRCUITS
Authors: KILIÇ RECAI , YILDIRIM FATMA
Published: May 2006

In this paper, we have experimentally investigated Current-Feedback Operational Amplifier (CFOA)-based inductorless Mixed-Mode Chaotic Circuit by constructing an experimental setup, experimentally verifying the static and dynamic performance of the proposed implementation.
STRONG CHAOTIFICATION OF DISCRETE TIME SYSTEMS BY SMALL FEEDBACK CONTROL
Authors: BOYARSKY ABRAHAM , GÓRA PAWEŁ
Published: May 2006

The problem of making a stable discrete time system chaotic has attracted considerable interest. The definition of chaotification used in these studies is based on introducing a feedback control which establishes the existence of a scrambled set for the controlled system. In this note, we introduce a stronger and potentially more useful definition of chaotification based on the existence of an absolutely continuous invariant measure (acim). The utility of this approach is that once a desired chaotic behavior (in the form of an acim near a stable fixed point) is specified, we can determine a small feedback control (as a function of the stable system) such that the controlled dynamical system exhibits the desired behavior. An example is worked out in detail.
GHOST STOCHASTIC RESONANCE IN AN ELECTRONIC CIRCUIT
Authors: CALVO OSCAR , CHIALVO DANTE R.
Published: May 2006

We demonstrate experimentally the regime of ghost stochastic resonance in the response of a Monostable Schmit Trigger electronic circuit driven by noise and signals with N frequency components: kf0+Δf, (k+1)f0+Δf,…, k+nf0+Δf where k is an integer greater than one. It is verified that stochastic resonance occurs at the frequency fr = f0 + (Δf/(k+(N-1)/2)), as predicted in the theory. At the frequency for which the resonance is maximum there is no input energy, and thus this form is called "ghost" stochastic resonance.
ON MULTIDIMENSIONAL ω-CHAOS
Authors: BOBOK JOZEF
Published: May 2006

Following the question of Smítal and Štefánková we show that there exist continuous maps of [0,1]n, n=2,3,… possessing an ω-scrambled set of the full n-dimensional Lebesgue measure.
A NOTE ON THE CRITICAL PERIODS OF POTENTIAL SYSTEMS
Authors: MAÑOSAS F. , VILLADELPRAT J.
Published: May 2006

In this paper, we consider the planar differential system associated with the potential Hamiltonian H(x,y) = (1/2)y2+V(x) where V(x) = (1/2)x2+(a/4)x4+(b/6)x6 with b ≠ 0. This family of differential systems always has a center at the origin and, eventually, three other period annuli. We prove that the corresponding period functions can have at most one critical period altogether. More precisely, we show that this critical period is simple and that it corresponds to the period function associated to the center at the origin. To prove the result we use that the period function verifies a Picard–Fuchs equation. Finally we describe the bifurcation diagram of the period function of the center at the origin.
SYMMETRY AND SYNCHRONY IN COUPLED CELL NETWORKS 1: FIXED-POINT SPACES
Authors: ANTONELI FERNANDO , STEWART IAN
Published: May 2006

Equivariant dynamical systems possess canonical flow-invariant subspaces, the fixed-point spaces of subgroups of the symmetry group. These subspaces classify possible types of symmetry-breaking. Coupled cell networks, determined by a symmetry groupoid, also possess canonical flow-invariant subspaces, the balanced polydiagonals. These subspaces classify possible types of synchrony-breaking, and correspond to balanced colorings of the cells. A class of dynamical systems that is common to both theories comprises networks that are symmetric under the action of a group Γ of permutations of the nodes ("cells"). We investigate connections between balanced polydiagonals and fixed-point spaces for such networks, showing that in general they can be different. In particular, we consider rings of ten and twelve cells with both nearest and next-nearest neighbor coupling, showing that exotic balanced polydiagonals — ones that are not fixed-point spaces — can occur for such networks. We also prove the "folk theorem" that in any Γ-equivariant dynamical system on Rk the only flow-invariant subspaces are the fixed-point spaces of subgroups of Γ.
CHAOS GAME CHARACTERIZATION OF TEMPORAL PRECIPITATION VARIABILITY: APPLICATION TO REGIONALIZATION
Authors: GUTIÉRREZ J. M. , GALVÁN A. , COFIÑO A. S. , PRIMO C.
Published: May 2006

We present an application of the fractal "chaos game representation" method in climatology for characterizing temporal precipitation aggregation patterns. To this aim, we establish an analogy with linguistic analysis considering precipitation as a discrete variable (e.g. rain, no rain). Each weekly, or monthly, symbolic sequence of observed precipitation is then considered a "word" and the climatological time series observed at a particular gauge defines a "language." The distribution of different words within the language characterizes the particular precipitation aggregation scheme. In this paper we show that the chaos game representation method provides a graphical representation (a fractal pattern, or fingerprint) of the distribution of words and also gives a quantitative characterization in terms of parameters such as the box-counting dimension and the entropy. We show that different climates exhibit characteristic patterns with different fractal exponents and entropies. As an illustrative application, the method is used for automatic regionalization of a set of gauges in the Iberian peninsula, showing that these new indices outperform standard averaged statistics (monthly means, etc.).
CHARACTERIZATION OF CHAOTICITY IN THE TRANSIENT CURRENT THROUGH PMMA THIN FILMS
Authors: HACINLIYAN A. , SKARLATOS Y. , YILDIRIM H. A. , SAHIN G.
Published: May 2006

Chaotic behavior in the transient current through thin Aluminum-PMMA-Aluminum films has been analyzed for times ranging up to 30,000s, in the temperature range 293–363K for applied voltages in the range 10–80V. Time series analysis reveals a positive Lyapunov exponent consistently and reproducibly throughout this range. Power law relaxation as reflected by the autocorrelation function and the positive Lyapunov exponent show parallel behaviors as a function of applied electric field.
A NEW METHOD TO DESCRIBE BRANCHING PATTERNS AS ONE-VARIABLE ARRAY
Authors: KITAMURA T. , HONJO H.
Published: May 2006

In nature, especially in non-equilibrium physics, we can see many branching growth patterns. We devised a new method for easily analyzing such pattern structures. A pattern growing in real space is transformed into a one-variable array without destroying the essence of its structure. To validate the method, we analyzed a fractal pattern as an example. By comparing the fractal dimension of the pattern with several exponents of the transformed one-variable array, we discuss the effectiveness of transformation into one-variable arrays.
MULTIFRACTAL MEASURES ON SMALL-WORLD NETWORKS
Authors: CHANG K. H. , CHOI B. C. , YOON SEONG-MIN , KIM KYUNGSIK
Published: May 2006

We investigate the multifractals of the first passage time on a one-dimensional small-world network with reflecting and absorbing barriers. The multifractals can be obtained from the distribution of the first passage time at which the random walker arrives for the first time at an absorbing barrier after starting from an arbitrary initial site. Our simulation is found to estimate the fractal dimension D0 = 0.920 ~ 0.930 for the different network sizes and random rewiring fractions. In particular, the multifractal structure breaks down into a small-world network, when the rewiring fraction p is larger than the critical value pc = 0.3. Our simulation results are compared with the numerical computations for regular networks.
THE EFFECT OF DISORDER ON THE HIERARCHICAL MODULARITY IN COMPLEX SYSTEMS
Authors: NAGY D. , TIBÉLY G. , KERTÉSZ J.
Published: May 2006

Hierarchically modular systems show a sequence of scale separations in some functionality or property in addition to their hierarchical topology. Starting from regular, deterministic objects like the Vicsek snowflake or the deterministic scale free network by Ravasz et al., we first characterize the hierarchical modularity by the periodicity of some properties on a logarithmic scale indicating separation of scales. Then we introduce randomness by keeping the scale freeness and other important characteristics of the objects and monitor the changes in the modularity. In the presented examples, a sufficient amount of randomness destroys hierarchical modularity. Our findings suggest that the experimentally observed hierarchical modularity in systems with algebraically decaying clustering coefficients indicates a limited level of randomness.
Metabolic effect of a LoBAG30 diet in men with type 2 diabetes
Authors: Nuttall Frank Q. , Schweim Kelly , Hoover Heidi , Gannon Mary C.
Published: May 2006

We recently reported that in subjects with untreated type 2 diabetes a 5-wk diet of 30:30:40 carbohydrate/protein/fat ratio resulted in a significant decrease in 24-h integrated glucose, total %glycohemoglobin, and total cholesterol compared with a control diet of 55:15:30 carbohydrate/protein/fat given at the beginning of the 5-wk period. Body weight was stable and insulin was unchanged. We now present data on other hormones and metabolites considered to be affected by dietary macronutrient changes. The test diet resulted in an elevated fasting plasma total IGF-I, but not growth hormone. Urinary free cortisol was increased. Serum renin and urinary aldosterone remained unchanged. Blood pressure was stable. Serum creatinine and uric acid were increased. Urinary microalbumin was decreased. Creatinine clearance, serum B12, folate, homocysteine, TSH, and free thyroxine were unchanged. Total triiodothyronine was decreased. Plasma α-amino nitrogen, urea nitrogen, and serum albumin were increased. Urea production rate was increased such that a new steady state was present. The calculated urea production rate accounted for 84% of protein ingested on the control diet but only 68% on the test diet, suggesting net nitrogen retention on the latter. Overall, the lack of negative effects, the improved glucose control, and the positive nitrogen balance suggest such a diet will be beneficial for older subjects with type 2 diabetes. Nevertheless, the long-term effects and general applicability of the diet remain to be determined.
The regulation of IGFs and IGFBPs by prolactin in primary culture of fetal rat hepatocytes is influenced by maternal malnutrition
Authors: El Khattabi Ilham , Remacle Claude , Reusens Brigitte
Published: May 2006

During perinatal development, the regulation of IGF system appears to be growth hormone (GH) independent. By using highly purified primary fetal hepatocytes, we investigated the role of prolactin (PRL) in the regulation of IGF system and hepatocyte proliferation. We also analyzed the consequence of a maternal low-protein (LP) diet on the regulation of IGF, IGF-binding protein (IGFBP), and hepatocyte proliferation by prolactin. Pregnant Wistar rats were fed a control (C) diet (20% protein) or isocaloric (LP; 8%) diet throughout gestation. On day 21.5, fetal hepatocytes were cultured for 4 days and incubated with rat prolactin. In the C hepatocytes, PRL at 100 ng/ml decreased the abundance of IGFBP-1 and IGFBP-2 by 50 ( P < 0.05) and 60% ( P < 0.01), respectively. It also reduced by 70% the level of IGF-II mRNA ( P < 0.01). By contrast, PRL failed to modulate IGFBP-1 and IGFBP-2 production by LP hepatocytes, and this was associated with reduced abundance of the short form of PRL receptor ( P < 0.05). PRL had no effect on either the proliferation or the IGF-I production by C and LP hepatocytes, although it reduced the expression of IGF-II. These results suggest that prolactin influences hepatocyte proliferation in vitro by inhibiting IGFBP-1, IGFBP-2, and IGF-II levels, which may coincide with the decline of IGF-II observed in rodents during late gestation in vivo. On the other hand, maternal LP diet induces a resistance of fetal hepatocytes to PRL.
11β-Hydroxysteroid Dehydrogenase Type 2 Activity in Hypothalamic Paraventricular Nucleus Modulates Sympathetic Excitation
Authors: Zhang Zhi-Hua , Kang Yu-Ming , Yu Yang , Wei Shun-Guang , Schmidt Thomas J. , Johnson Alan Kim , Felder Robert B.
Published: May 2006

Aldosterone stimulates the sympathetic nervous system by binding to a select population of brain mineralocorticoid receptors (MR). These MR have an equal affinity for corticosterone that is present in substantially higher concentrations, but are held in reserve for aldosterone by activity of the enzyme 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD-2), which converts corticosterone to an inactive metabolite. Thus, colocalization of MR and 11β-HSD-2 activity may help identify brain regions that mediate the effects of aldosterone. The present studies tested the hypothesis that 11β-HSD-2 activity regulates MR-mediated responses in the paraventricular nucleus (PVN) of the hypothalamus, a forebrain region implicated in sympathetic regulation. Real-time–polymerase chain reaction revealed the presence of 11β-HSD-2 mRNA in PVN. In anesthetized adult male Sprague-Dawley rats, microinjection of the 11β-HSD-2 inhibitor carbenoxolone (CBX) into PVN increased mean arterial pressure, heart rate, and renal sympathetic nerve activity. Intracerebroventricular injections of CBX excited PVN neurons and increased mean arterial pressure, heart rate, and renal sympathetic nerve activity. The ability of CBX to increase sympathetic activity by inhibiting 11β-HSD-2, thereby permitting corticosterone to activate MR, was confirmed by the following: Intracerebroventricular glycyrrhizic acid, another 11β-HSD-2 inhibitor, mimicked the sympathoexcitatory effects of CBX; the sympathoexcitatory effects of CBX were blocked by spironolactone, a MR antagonist. Neither CBX nor glycyrrhizic acid elicited a response in adrenalectomized rats. These findings suggest that MR in PVN contribute to sympathetic regulation and may be activated by aldosterone or corticosterone (or cortisol in humans) depending on the state of 11β-HSD-2 activity.
Telmisartan Prevents Obesity and Increases the Expression of Uncoupling Protein 1 in Diet-Induced Obese Mice
Authors: Araki Kana , Masaki Takayuki , Katsuragi Isao , Tanaka Katsuhiro , Kakuma Tetsuya , Yoshimatsu Hironobu
Published: May 2006

The aim of the present study was to clarify the effect of telmisartan, an angiotensin II receptor blocker, on the development of obesity and related metabolic disorders in diet-induced obese mice. Treatment with telmisartan dissolved in drinking water at a dosage of 5 mg/kg per day for 14 days attenuated the diet-induced weight gain without affecting food intake in diet-induced obese mice compared with controls using nontreated water. Telmisartan treatment decreased the weight of visceral adipose tissue and the triglyceride content in the liver and skeletal muscle. In addition, hyperglycemia, hyperinsulinemia, and hypertriglyceridemia in diet-induced obese mice all improved with telmisartan treatment. Furthermore, telmisartan treatment increased adiponectin mRNA in visceral white adipose tissue and was associated with a concomitant change in the serum adiponectin level. In contrast, the treatment reduced the serum level of resistin. Finally, telmisartan treatment increased the mRNA expression of uncoupling protein 1 in brown adipose tissue and was accompanied by an increase in oxygen consumption. In conclusion, telmisartan treatment might prevent the development of obesity and related metabolic disorders by altering the levels of adiponectin, resistin, and uncoupling protein 1 in diet-induced obese mice. Our results indicate that telmisartan can be used as a therapeutic tool for metabolic syndrome, including visceral obesity.
Influences of Norepinephrine Transporter Function on the Distribution of Sympathetic Activity in Humans
Authors: Mayer Antje F. , Schroeder Christoph , Heusser Karsten , Tank Jens , Diedrich André , Schmieder Roland E. , Luft Friedrich C. , Jordan Jens
Published: May 2006

Previous studies suggest that neuronal norepinephrine transporter function may regulate the distribution of sympathetic activity among blood vessels, heart, and kidney; we tested the functional relevance in humans. Sixteen healthy men (26±1 years) ingested 8 mg of the selective norepinephrine reuptake transporter inhibitor reboxetine or a matching placebo on 2 separate days in a double-blind, randomized, crossover fashion. We monitored heart rate, thoracic bioimpedance, blood pressure, glomerular filtration rate, and renal blood flow. Ninety minutes after ingestion of the test medication, subjects were tilted to a 45° head-up position, where they remained for an additional 30 minutes. Reboxetine increased supine systolic blood pressure through an increase in cardiac output whereas systemic vascular resistance decreased. Furthermore, reboxetine increased heart rate, particularly with a head-up tilt. Supine plasma renin activity was 0.71±0.15 ng angiotensin (Ang)/L per mL/h with placebo and 0.36±0.07 ngAng/L per mL/h with reboxetine (
P
<0.01). Supine plasma Ang II concentrations were also decreased with reboxetine. Both plasma renin activity and Ang II concentrations remained suppressed during head-up tilt. On placebo, renal vascular resistance increased with head-up tilt. The response was abolished with norepinephrine reuptake inhibition. We conclude that norepinephrine reuptake function profoundly influences the distribution of sympathetic activity between the heart, vasculature, and kidney in humans. All of these changes are physiologically relevant because they lead to corresponding changes in organ function.
Maturational and Adaptive Modulation of Left Ventricular Torsional Biomechanics
Authors: Notomi Yuichi , Srinath Gowdagere , Shiota Takahiro , Martin-Miklovic Maureen G. , Beachler Lisa , Howell Kelly , Oryszak Stephanie J. , Deserranno Dimitri G. , Freed Alan D. , Greenberg Neil L. , Younoszai Adel , Thomas James D.
Published: May 2006

Background—

Left ventricular (LV) torsional deformation, based in part on the helical myocardial fiber architecture, is an important component of LV systolic and diastolic performance. However, there is no comprehensive study describing its normal development during childhood and adult life.

Methods and Results—

Forty-five normal subjects (25 children and 20 adults; aged 9 days to 49 years; divided into 5 groups: infants, children, adolescents, and young and middle-age adults) underwent assessment of LV torsion and untwisting rate by Doppler tissue imaging. LV torsion increased with age, primarily owing to augmentation in basal clockwise rotation during childhood and apical counterclockwise rotation during adulthood. Although LV torsion and untwisting overall showed age-related increases, when normalized by LV length, they showed higher values in infancy and middle age. The proportion of untwisting during isovolumic relaxation was lowest in infancy, increased during childhood, and leveled off thereafter, whereas peak untwisting performance (peak untwisting velocity normalized by peak LV torsion) showed a decrease during adulthood.

Conclusions—

We have shown the maturational process of LV torsion in normal subjects. Net LV torsion increases gradually from infancy to adulthood, but the determinants of this were different in the 2 age groups. The smaller LV isovolumic untwisting recoil during infancy and its decline in adulthood may suggest mechanisms for alterations in diastolic function.
Inhibiting p90 Ribosomal S6 Kinase Prevents Na
+
-H
+
Exchanger–Mediated Cardiac Ischemia-Reperfusion Injury
Authors: Maekawa Naoya , Abe Jun-ichi , Shishido Tetsuro , Itoh Seigo , Ding Bo , Sharma Virendra K. , Sheu Shey-Shing , Blaxall Burns C. , Berk Bradford C.
Published: May 2006

Background—

Pharmacological and genetic studies indicate that the Na
+
-H
+
exchanger isoform 1 (NHE1) plays a critical role in myocardial ischemia and reperfusion (I/R) injury. We found that p90 ribosomal S6 kinase (RSK) phosphorylated serine 703 of NHE1, stimulating 14–3–3 binding and NHE1 activity. Therefore, we hypothesized that inhibiting RSK in cardiomyocytes would prevent NHE1 activation and decrease I/R-mediated injury.

Methods and Results—

To examine the role of RSK in vivo, we generated transgenic mice with cardiac-specific overexpression of dominant negative RSK (DN-RSK-TG). DN-RSK-TG hearts demonstrated normal basal cardiac function and morphology. However, myocardial infarction (left coronary artery occlusion for 45 minutes) in DN-RSK-TG hearts was significantly reduced at 24 hours of reperfusion from 46.9±5.6% area at risk in nontransgenic littermate controls to 26.0±4.2% in DN-RSK-TG (
P
<0.01). Cardiomyocyte apoptosis was significantly reduced after I/R in DN-RSK (0.9±0.2%) compared with nontransgenic littermate controls (6.2±2.6%). Importantly, activation of RSK and interaction of 14–3–3 with NHE1, necessary for agonist-stimulated NHE1 activity, were increased by I/R and inhibited by 70% in DN-RSK-TG (
P
<0.01). Next, we transduced rat neonatal cardiomyocytes with adenovirus-expressing DN-RSK (Ad.DN-RSK) and measured NHE1 activity. The baseline rate of pH recovery in acid-loaded cells was equal in cells expressing LacZ or DN-RSK. However, NHE1 activation by 100 μmol/L H
2
O
2
was significantly inhibited in cells expressing DN-RSK (0.16±0.02 pH units/min) compared with Ad.LacZ (0.49±0.13 pH units/min). Apoptosis induced by 12 hours of anoxia followed by 24 hours’ reoxygenation was significantly reduced in cells expressing Ad.DN-RSK (18.6±2.0%) compared with Ad.LacZ (29.3±5.4%).

Conclusions—

In summary, RSK is a novel regulator of cardiac NHE1 activity by phosphorylating NHE1 serine 703 and a new pathological mediator of I/R injury in the heart.
Percutaneous Treatment With Drug-Eluting Stent Implantation Versus Bypass Surgery for Unprotected Left Main Stenosis
Authors: Chieffo Alaide , Morici Nuccia , Maisano Francesco , Bonizzoni Erminio , Cosgrave John , Montorfano Matteo , Airoldi Flavio , Carlino Mauro , Michev Iassen , Melzi Gloria , Sangiorgi Giuseppe , Alfieri Ottavio , Colombo Antonio
Published: May 2006

Background—

Improvements in results with percutaneous coronary intervention (PCI) with drug-eluting stents (DES) may extend their use in patients with left main coronary artery (LMCA) stenosis.

Methods and Results—

Two hundred forty-nine patients with LMCA stenosis were treated with PCI and DES implantation (n=107) or coronary artery bypass grafting (CABG) (n=142), in a single center, between March 2002 and July 2004. A propensity analysis was performed to adjust for baseline differences between the two cohorts. At 1 year, there was no statistical difference in the occurrence of death in PCI versus CABG both for the unadjusted (OR=0.291; 95% CI=0.054 to 1.085;
P
=0.0710) and adjusted analyses (OR=0.331; 95% CI=0.055 to 1.404;
P
=0.1673). PCI was correlated to a lower occurrence of the composite end points of death and myocardial infarction (unadjusted OR=0.235; 95% CI=0.048 to 0.580;
P
=0.0002; adjusted OR=0.260; 95% CI=0.078 to 0.597;
P
=0.0005) and death, myocardial infarction, and cerebrovascular events (unadjusted OR=0.300; 95% CI=0.102 to 0.617;
P
=0.0004; adjusted OR=0.385; 95% CI=0.180 to 0.819;
P
=0.01). No difference was detected in the occurrence of major adverse cardiac and cerebrovascular event at the unadjusted (OR=0.675; 95% CI=0.371 to 1.189;
P
=0.1891) and adjusted analyses (OR=0.568; 95% CI=0.229 to 1.344;
P
=0.2266).

Conclusions—

At 1 year, in this single-center, retrospective experience, there was no difference in the degree of protection against death, stroke, myocardial infarction, and revascularization between PCI with DES and CABG for LMCA disease. (Circulation. 2006;113:2542-2547.)
Significance of a Fragmented QRS Complex Versus a Q Wave in Patients With Coronary Artery Disease
Authors: Das Mithilesh K. , Khan Bilal , Jacob Sony , Kumar Awaneesh , Mahenthiran Jo
Published: May 2006

Background—

Q waves on a 12-lead ECG are markers of a prior myocardial infarction (MI). However, they may regress or even disappear over time, and there is no specific ECG sign of a non–Q-wave MI. Fragmented QRS complexes (fQRSs), which include various RSR′ patterns, without a typical bundle-branch block are markers of altered ventricular depolarization owing to a prior myocardial scar. We postulated that the presence of an fQRS might improve the ability to detect a prior MI compared with Q waves alone by ECG.

Methods and Results—

A cohort of 479 consecutive patients (mean±SD age, 58.2±13.2 years; 283 males) who were referred for nuclear stress tests was studied. The fQRS included various morphologies of the QRS (<120 ms), which included an additional R wave (R′) or notching in the nadir of the S wave, or >1 R′ (fragmentation) in 2 contiguous leads, corresponding to a major coronary artery territory. The Q wave was present in 71 (14.8%) patients, an fQRS was present in 191 (34.9%) patients, and an fQRS and/or a Q wave was present in 203 (42.3%) patients. Sensitivity, specificity, and the negative predictive value for myocardial scar as detected by single photon emission computed tomography analysis were 36.3%, 99.2%, and 70.8%, respectively, for the Q wave alone; 85.6%, 89%, and 92.7%, respectively, for the fQRS; and 91.4%, 89%, and 94.2%, respectively, for the Q wave and/or fQRS.

Conclusions—

The fQRS on a 12-lead ECG is a marker of a prior MI, defined by regional perfusion abnormalities, which has a substantially higher sensitivity and negative predictive value compared with the Q wave.
Enhanced Ventricular Untwisting During Exercise
Authors: Notomi Yuichi , Martin-Miklovic Maureen G. , Oryszak Stephanie J. , Shiota Takahiro , Deserranno Dimitri , Popovic Zoran B. , Garcia Mario J. , Greenberg Neil L. , Thomas James D.
Published: May 2006

Background—

The cascade of events by which early diastolic left ventricular (LV) filling increases with exercise is not fully elucidated. Doppler tissue imaging (DTI) can detect myocardial motion, including torsion, whereas color M-mode Doppler (CMM) can quantify LV intraventricular pressure gradients (IVPGs).

Methods and Results—

Twenty healthy volunteers underwent echocardiographic examination with DTI at rest and during submaximal supine bicycle exercise. We assessed LV long-/short-axis function, torsion, volume, inflow dynamics, and early diastolic IVPG derived from CMM data. LV torsion and untwisting velocity increased with exercise (torsion, 11±4° to 24±8°; untwisting velocity, −2.0±0.7 to −5.6±2.3 rad/s) that was associated with an increase in IVPG (1.4±0.5 to 3.7±1.2 mm Hg). Untwisting in normal subjects occurred during isovolumic relaxation and early filling, significantly before long-axis lengthening or radial expansion. The clinical feasibility of this method was tested in 7 patients with hypertrophic cardiomyopathy (HCM); torsion was higher at rest but did not increase with exercise (16±4° to 14±6°), whereas untwisting was delayed and unenhanced (−1.6±0.8 to −2.3±1.2 rad/s). In concert, IVPG was similar at rest (1.2±0.3 mm Hg), but the exercise response was blunted (1.6±0.8 mm Hg). In normal subjects and HCM patients, there was a similar linear relation between IVPG and untwisting rate, with an overall correlation coefficient of
r
=0.75 (
P
<0.0001).

Conclusions—

LV untwisting appears to be linked temporally with early diastolic base-to-apex pressure gradients, enhanced by exercise, which may assist efficient LV filling, an effect that appears blunted in HCM. Thus, LV torsion and subsequent rapid untwisting appear to be manifestations of elastic recoil, critically linking systolic contraction to diastolic filling.
Effects of Nitroglycerin on Erythrocyte Rheology and Oxygen Unloading
Authors: Bin Jian-Ping , Doctor Allan , Lindner Jonathan , Hendersen Edward M. , Le D. Elizabeth , Leong-Poi Howard , Fisher Nicholas G. , Christiansen Jonathan , Kaul Sanjiv
Published: May 2006

Background—

We hypothesized that nitroglycerin improves O
2
delivery to ischemic tissue by altering erythrocyte rheology and O
2
unloading through an increase in bioactive nitric oxide (NO) content.

Methods and Results—

Twelve dogs with resting flow-reducing single-vessel stenosis were studied at rest and during intracoronary infusion of nitroglycerin (0.3 to 0.6 μg · kg
−1
· min
−1
). Half the dogs also had occlusion of the remote coronary artery to remove any collateral effects. Systemic and coronary hemodynamics, myocardial blood flow (MBF), whole blood viscosity (WBη), erythrocyte charge (EC) and mobility (EM), regional myocardial O
2
delivery and consumption, and tissue O
2
pressure (P
o
2
) were measured. No changes in systemic hemodynamics were seen with nitroglycerin. Despite flow-limiting stenosis, MBF increased significantly in the central 25% of the ischemic bed, which was associated with an approximately 19% decrease in WBη. There was a good correlation (
r
=0.87) between the two. The decrease in WBη was associated with a decrease in EC and an increase in EM (
r
=0.83). The nitroglycerin-induced increase in tissue P
o
2
was disproportionate to the increase in MBF, indicating enhanced O
2
unloading. Erythrocyte S-nitrosothiol content (reflecting mainly S-nitrosohemoglobin) was significantly higher for blood exposed in vitro to 0.1 μmol/L nitroglycerin or the NO donor SNAP, as compared with control (18.9±8.8 and 10.5±6.5 versus 2.6±0.5×10
−5
,
P
<0.05).

Conclusions—

The augmented MBF in the ischemic microcirculation during nitroglycerin administration occurs in tandem with increased erythrocyte S-nitrosothiol content, EM, and O
2
unloading. These additional microvascular mechanisms may contribute to the powerful antiischemic effects of nitroglycerin, especially during low-flow states.
Limited Contribution of Photovoltaic Energy Technology to Economic Development of Sub-Saharan Africa
Authors:   Soboyejo,   Otiti
Published: May 2006

This paper argues that the cost of solar PV system is beyond the reach of most rural poor households in sub-Saharan Africa. The other disadvantage of PV technology is limited power output. PV technology is unsuitable for agro-processing activities that represent the most attractive options for generating incomes in sub-Saharan Africa. Agro-processing activities require equipment with average power output of not less than 1000 W. A PV system of 1000 W is suggested as being too costly for most rural homes, based on the current silicon technologies. The paper concludes by suggesting that sub-Saharan Africa urgently needs alternative energy technologies that can meet the overall energy requirements of the region and promote economic development in the rural areas. Alternative approaches are also suggested to improve the effectiveness of PV technology in providing the energy needs in sub-Saharan Africa in the short, medium and long term.
Paradigms and Reality in Micro-Finance: The Indian Case
Authors: Edward Peter , Olsen Wendy
Published: May 2006

In India, micro-finance has grown rapidly. We examine qualitative local data on micro-finance in southern Andhra Pradesh. We compare and contrast Mayoux's three paradigms of micro-finance as being differentiated by their assumptions, their claims, and the mode of operation of those who adhere to them. Each paradigm offers a grounding for practice as well as a mode of discourse for microfinance practitioners. In Andhra Pradesh, the empowerment paradigm is fading away compared with the financial sustainability paradigm of micro-finance. The anti-poverty paradigm is also muted. The financial sustainability school is presently dominant in this complex micro-enterprise scene.
An Alternative Holistic Approach to Affordable Housing: Homes of Foam
Authors:   Okwo,   Soboyejo
Published: May 2006

This paper presents a holistic alternative approach to the development of a model of affordable housing within the context of Nigeria. This includes the use of low-cost expanded polystyrene (EPS) foams, solar energy, and rainwater harvesting. The holistic framework also considers the infrastructural requirements and a recreational park that is integrated into a model housing scheme. A cost model is used to estimate the minimum construction costs. The long-term mortgage implications of the results are discussed for the development of affordable housing for low- to medium-income families in developing countries such as Nigeria.
Issues of Identity in the Indian Diaspora: A Transnational Perspective
Authors: Sahoo Ajaya Kumar
Published: May 2006

India is unique for the magnitude of her diversities in terms of languages and regions, religions and sects, castes and sub-castes, rural and urban, food and style of dress, which are also reflected by her diasporic communities. There are diasporic communities formed on the basis of linguistic or regional identities such as Punjabis, Gujaratis, Sindhis, Tamils, Malayalees and Telugus. Global organizations such as Global Organization of People of Indian Origin (GOPIO), World Telugu Federation (WTF), and World Punjabi Organization (WPO), have recently emerged to preserve and promote the identities and cultures of Indians, uniting transnationally India and the global Indian diaspora. The past decade has witnessed a phenomenal dynamism among the diasporic communities, made possible by the recent advancement in technologies of travel, transport, and communications. Not only did these developments bring the diasporic communities and their motherland closer but they also facilitated in bringing together the members of their community dispersed around the world. The present article examines this emerging trend with the illustration of one of the important regional Indian diasporic communities, the Gujarati Diaspora. Gujaratis, the people from the central western parts of India, are one of the early Indian communities who have ventured out to different parts of the world for multiple reasons. Today, as one of the prominent Indian diasporic communities in the world, Gujaratis are successful not only in business, which is their first love, but also in professional fields such as technology, science, medicine, and business management.
The International Mariology Project: a Case-study of Augustine's Letters
Authors: Allen Pauline
Published: May 2006

This study of the mariology of the letters of Augustine is part of an international project investigating the development of the cult of Mary before 431. The study argues that the works of authors before this date need to be considered individually, and that negative, ambiguous, or seemingly contradictory findings, as well as data in which Mary figures abundantly, are all valid. The scant role assigned to Mary in Augustine's letters, where she is mostly a credal commodity, stands in stark contrast to the high mariology found in some of his other works, indicating that genre affects the data. An aggregate score of high mariology in the one author, Augustine in this case, does not mean that this score holds true for all his works. A low score must be also taken into serious consideration, and indeed it can be just as important in understanding the development of the cult of Mary before 431.
Conserving Nature, but to What end?
Authors: Carolan Michael S.
Published: May 2006

The author examines various cases of conservation policies in practice, and the implication of those practices in terms of the ecologies they support, showing, in the end, that the “nature” being preserved is not always the one intended. In doing this, insights are also gleaned to inform how we should do environmental sociology, and what lies in environmental sociology's future if we work toward this end. The author argues that environmental sociology needs to become more environmental: to be willing to understand sociobiophysical relationships in all their complexity, even in those cases that require a well-grounded understanding of ecosystem processes. Thus, although retaining focus on the historical subject, which shapes conceptions of and ultimately practices toward ecology, we must also begin to view this subject as also an ecological object. The implications of such an analytic move, in terms of what it means for environmental sociology's future, are then discussed.
Florence Kelley and the Struggle Against the Degradation of Life
Authors: Clark Brett , Foster John Bellamy
Published: May 2006

Florence Kelley illuminated how degraded environments stemmed from the social relations and operations of industrial capitalism. As a social reformer, she worked to document the various dangers that workers confronted. She presented how laborers were exposed to noxious gases, toxic substances, and poisonous chemicals and dyes. Dangerous materials, such as arsenic, were introduced into the production process without a concern for their health implications. Kelley's critique of industrial capitalism and its exploitation of workers, especially in the form of child labor, revealed how a productive process driven by the accumulation of capital threatened the health of all people and hindered social development. She fought to make the public aware of the dangerous materials and hazardous conditions that were involved in the production of items for market. Kelley worked to unite consumers and laborers in a campaign to improve industrial relations, recognizing that a radical transformation of social relations was necessary in order to stop the degradation of life.
Environmental Scanning and Information Source Utilization: Exploring the Behavior of Hong Kong Hotel and Tourism Executives
Authors: Jogaratnam Giri , Law Rob
Published: May 2006

Different levels within the management hierarchy will have varying needs for information and will rely on diverse sources and utilize different types of information. This study examined current information acquisition practices adopted by hotel and tourism industry managers in Hong Kong. Data were collected by way of a survey questionnaire. Findings are reported pertaining to scanning attention ascribed to the task and remote environments, perceived importance of information source, frequency of information source usage, and the use of computer systems in environmental scanning.
Predictors of Relationship Quality and Relationship Outcomes in Luxury Restaurants
Authors: Kim Woo Gon , Lee Yong-Ki , Yoo Young-Jin
Published: May 2006

This study examines the relationships among elements of relationship management activities (predictors), relationship quality (a mediating construct), and relationship outcomes (commitment, loyalty, and word of mouth). Despite much research focusing on relationship quality, some central questions concerning the relationship among the three constructs have not been fully explored. A conceptual model was developed and tested to examine the mediating effect of relationship quality on the relationship between the seven relationship management activities and the three relationship outcomes. Structural equation analyses on the data collected from a survey of 887 dinner patrons at 21 luxury restaurants show that relationship quality is the primary mediating construct between relationship management activities and relationship outcomes. The effective use of a relationship management strategy may increase customer commitment, spread positive word of mouth, and generate loyalty. The findings of this study provide restaurant managers with a guideline for developing and implementing an enhanced relationship management strategy.
Testing the Determinants of Computerized Reservation System Users’ Intention to Use Via a Structural Equation Model
Authors: Lee Hae Young , Kim Woo Gon , Lee Yong-Ki
Published: May 2006

This study examines the relationship between users’ personal perceptions and beliefs of the proposed system and their normal day-to-day usage in the context of the travel industry’s computerized reservation systems (CRSs). Using a technology acceptance model as a theoretical background, the influences of three dimensions of fit (i.e., task fit, career fit, and organization fit) on CRS users’ daily routine usage are further explored. Results suggested that proposed users’ usage intentions are motivated by their various evaluations of the given system. Diverse system features and functions should thus be experienced and emphasized in advance according to each organization’s unique business situation. Such experience with the proposed CRS enables users to develop more favorable perceptions and beliefs of the given system, leading consequently to a higher level of day-to-day usage.
Estimation of Weight of Solid Waste: Newspapers in Hong Kong Hotels
Authors: Chan Wilco , Wong Kevin
Published: May 2006

This study aims to investigate the severity of the solid waste problem created by the local hotels, particularly with regard to the volume and total weight of newspapers distributed in hotels. Based on interviews with housekeepers, the study identified two groups of newspapers and proceeded to estimate the weight of the newspapers distributed in hotels using independent variables - the number of occupied room nights, intergroup ratio, average weight of newspapers, and country mix of in-house guests. A total of 52 hotels, representing two thirds (67%) of hotels in Hong Kong, responded to the survey. It was found that the total number of copies and total weight of distributed newspapers in 2002 reached 18 million and 5.6 million kilograms, respectively. Particularly, four-star hotels carried the largest number and the highest weight of newspapers. Suggestions for handling solid waste were recommended based on the findings.
Strategy Implementation Success: The Moderating Effects of Size and Environmental Complexity and the Mediating Effects of Involvement
Authors: Harrington Robert J. , Kendall K. W.
Published: May 2006

This study examines the importance of foodservice managers’ and organizational members’ involvement in the implementation of strategy. The study assesses the direct and moderating effects of managers’ perception of environmental complexity and firm size on level of involvement during strategy implementation. Findings indicate that firms operating in an environment of greater complexity bring more organizational members into the implementation process. Firm size interacted with complexity to drive higher involvement levels for small and large firms. Furthermore, foodservice firms that utilized implementation processes that involved more organizational members across the hierarchy achieved greater success in strategy implementation. Level of involvement was shown to mediate the relationship between external complexity and implementation success.
Guest Perceptions of Hotel Loyalty
Authors: Mason David DM , Tideswell Carmen , Roberts Elizabeth
Published: May 2006

This research reports on a qualitative survey of hotel guest loyalty. The approach was unusual in several ways: It sought to measure loyalty in the general population of hotel users rather than selecting a population already known to be loyal, and instead of trying to identify personality traits in the guests’ psychology that might be important, or ranking features of the hotel that might be determining factors, guests were simply asked what the term hotel loyalty meant to them. This approach has the advantage of not being influenced by any particular theory or restricted by the scope of the questions asked. The outcome of the analysis of their responses is a model of hotel loyalty created directly from the guests’ own perceptions of loyalty. The model shows that “loyalty” is actually a dynamic concept balancing seven elements already found in previous research and involves an unstated or implied contract between the guest and the hotel. It also suggests that many of the determinants commonly held to influence loyalty are, in fact, not relevant.