bluuebunny/crossref_metadata_2025 huggingface dataset:
Factors Affecting Perioperative Transfusion Decisions in Patients with Coronary Artery Disease Undergoing Coronary Artery Bypass Surgery
Authors: Shehata Nadine , Wilson Kumanan , Mazer C David , Tomlinson George , Streiner David , Hebert Paul , Naglie Gary
Published: June 2006

Background

A high proportion of patients having cardiac bypass surgery receive erythrocyte transfusions. Decisions about when to transfuse patients having surgery for coronary artery disease may impact on erythrocyte utilization and patient morbidity and mortality. There are no published data about the factors that influence physicians' decisions to transfuse erythrocytes to these patients. The objectives of this study were to determine the hemoglobin concentration for transfusion and the factors that influence physicians' perioperative transfusion decisions for coronary artery bypass patients.

Methods

The authors conducted a cross-sectional study using pretested, self-administered, mailed questionnaires sent in 2004 to all cardiac surgeons and anesthesiologists in Canada who participate in coronary artery bypass surgery. The questionnaire included four intraoperative and four postoperative vignettes. Factors assessed included patient age, sex, cardiac index, and myocardial ischemia.

Results

The response rates were 70% (345 of 489) for the intraoperative and 61% (297 of 489) for the postoperative case scenarios. The mean hemoglobin concentrations for transfusion were 7.0 g/dl for the intraoperative case scenarios and 7.2 g/dl for the postoperative case scenarios. Older age, the presence of myocardial ischemia, and a low cardiac index were factors that increased the hemoglobin concentration for transfusion (P < 0.0001). Physicians ranked myocardial ischemia as the most significant factor affecting their transfusion decisions.

Conclusions

Factors such as the presence of a low cardiac index, myocardial ischemia, and older age increase the hemoglobin concentrations at which physicians transfuse coronary bypass surgery patients. Future studies are required to elucidate whether transfusions based on these variables affect patient morbidity and mortality.
Splanchnic Oxygen Consumption Is Impaired during Severe Acute Normovolemic Anemia in Anesthetized Humans
Authors: Mathru Mali , Solanki Daneshvari R. , Woodson Lee C. , Funston J Sean , Ozkan Orthan , Henkel Sheryl N. , Wang Deli , Gore Dennis , Prough Donald S.
Published: June 2006

Background

In conscious humans, reduction in hemoglobin concentration to 5 g/dl did not produce inadequate systemic oxygenation. However, systemic measures of inadequate oxygenation may not be sufficiently sensitive to detect inadequate oxygenation in individual organs such as splanchnic organs. The authors tested the hypothesis that acute normovolemic anemia to hemoglobin less than 6.0 g/dl in anesthetized humans reduces splanchnic oxygen consumption because of diminished whole body oxygen delivery.

Methods

Elective spine (n = 12) and abdominal (n = 7) surgery patients underwent acute normovolemic anemia to decrease the hemoglobin concentration close to 6.0 g/dl. The authors assessed the development of supply-dependent conditions in systemic and regional vascular beds by two primary measures before and after acute normovolemic anemia: oxygen consumption and surrogate biochemical markers of anaerobic metabolism, including plasma lactate, regional lactate kinetics, and ketone body ratio.

Results

When hemoglobin was reduced from 13.6 +/- 1.2 to 5.9 +/- 0.3 g/dl, oxygen supply dependency occurred in the splanchnic and preportal tissues but not at the systemic level. Regional supply dependency was accompanied by biochemical markers of anaerobic metabolism.

Conclusions

In anesthetized humans, a reduction in hemoglobin to 5.9 g/dl by acute normovolemic anemia diminished splanchnic and preportal whole body oxygen delivery and impaired splanchnic and preportal oxygen consumption. This was accompanied by increased plasma levels of regional lactate and an increased beta-hydroxybutyrate-to-acetoacetate ratio. These findings suggest that the risk to the gastrointestinal tract during acute normovolemic anemia may be underestimated.
Effect of Propofol Anesthesia and Continuous Positive Airway Pressure on Upper Airway Size and Configuration in Infants
Authors: Crawford Mark W. , Rohan Denise , Macgowan Christopher K. , Yoo Shi-Joon , Macpherson Bruce A.
Published: June 2006

Background

Infants are prone to obstruction of the upper airway during general anesthesia. Continuous positive airway pressure (CPAP) is often used to prevent or treat anesthesia-induced airway obstruction. The authors studied the interaction of propofol anesthesia and CPAP on airway caliber in infants using magnetic resonance imaging.

Methods

Nine infants undergoing elective magnetic resonance imaging of the brain were studied. Head position was standardized. Spin echo magnetic resonance images of the airway were acquired at the level of the soft palate, base of the tongue, and tip of the epiglottis. Four sets of images were acquired in sequence: (1) during light propofol anesthesia at an infusion rate of 80 microg . kg(-1) . min(-1), (2) after increasing the depth of propofol anesthesia by administering a bolus dose (2.0 mg/kg) and increasing the infusion rate to 240 microg . kg(-1) . min(-1), (3) during continued infusion of 240 microg . kg(-1). min propofol and application of 10 cm H2O CPAP, and (4) after removal of CPAP and continued infusion of 240 microg . kg(-1). min propofol.

Results

Increasing depth of propofol anesthesia decreased airway caliber at each anatomical level, predominantly due to anteroposterior narrowing. Application of CPAP completely reversed the propofol-induced decrease in airway caliber, primarily by increasing the transverse dimension.

Conclusions

Airway narrowing with increasing depth of propofol anesthesia results predominantly from a reduction in anteroposterior dimension, whereas CPAP acts primarily to increase the transverse dimension. Although airway caliber during deep propofol anesthesia and application of CPAP was similar to that during light propofol anesthesia, there were significant configurational differences.
Antagonistic Actions of Halothane and Sevoflurane on Spontaneous Ca2+Release in Rat Ventricular Myocytes
Authors: Graham Mark D. , Hopkins Philip M. , Harrison Simon M.
Published: June 2006

Background

Halothane has been reported to sensitize Ca(2+) release from the sarcoplasmic reticulum (SR), which is thought to contribute to its initial positive inotropic effect. However, little is known about whether isoflurane or sevoflurane affect the SR Ca(2+) release process, which may contribute to the inotropic profile of these anesthetics.

Methods

Mild Ca(2+) overload was induced in isolated rat ventricular myocytes by increase of extracellular Ca(2+) to 2 mM. The resultant Ca(2+) transients due to spontaneous Ca(2+) release from the SR were detected optically (fura-2). Cells were exposed to 0.6 mM anesthetic for a period of 4 min, and the frequency and amplitude of spontaneous Ca(2+) transients were measured.

Results

Halothane caused a temporary threefold increase in frequency and decreased the amplitude (to 54% of control) of spontaneous Ca(2+) transients. Removal of halothane inhibited spontaneous Ca release before it returned to control. In contrast, sevoflurane initially inhibited frequency of Ca(2+) release (to 10% of control), whereas its removal induced a burst of spontaneous Ca(2+) release. Isoflurane had no significant effect on either frequency or amplitude of spontaneous Ca(2+) release on application or removal. Sevoflurane was able to ameliorate the effects of halothane on the frequency and amplitude of spontaneous Ca(2+) release both on application and wash-off.

Conclusions

Application of halothane and removal of sevoflurane sensitize the SR Ca(2+) release process (and vice versa on removal). Sevoflurane reversed the effects of halothane, suggesting they may act at the same subcellular target on the SR.
Flumazenil Mimics whereas Midazolam Abolishes Ischemic Preconditioning in a Rabbit Heart Model of Ischemia–Reperfusion
Authors: Rivo Julia , Raphael Jacob , Drenger Benjamin , Berenshtein Eduard , Chevion Mordechai , Gozal Yaacov
Published: June 2006

Background

The goal of the current study was to assess the effects of flumazenil, a benzodiazepine receptor antagonist, in limiting infarct size and in reducing hydroxyl free radical production.

Methods

After intravenous salicylate (100 mg/kg) administration, rabbits were subjected to 40 min of regional myocardial ischemia and 2 h of reperfusion. In one group, flumazenil (0.05 mg/kg) and, in another, midazolam (0.05 mg/kg) was administered 15 min before 40 min of ischemia. Ischemic preconditioning (IP) was elicited by 5 min of ischemia followed by 10 min of reperfusion (before the 40-min ischemia period). In two other groups, midazolam was added to flumazenil and IP. Infarct size was determined using triphenyl tetrazolium chloride staining. The authors quantified the hydroxyl-mediated conversion of salicylate to its 2,3- and 2,5-dihydroxybenzoate derivatives during reperfusion by high-performance liquid chromatography coupled with electrochemical detection. Results are expressed as mean +/- SEM.

Results

Flumazenil, like IP, significantly decreased infarct size (23 +/- 4 and 22 +/- 5%, respectively, vs. 57 +/- 6% in control group; P < 0.01). Midazolam inhibited the effects of flumazenil and IP. Flumazenil and IP significantly limited the increase in the normalized concentrations of 2,3- and 2,5-dihydroxybenzoic acids. With midazolam, however, the increase was comparable to that of the control group. 5-Hydroxydecanoate, a selective mitochondrial adenosine triphosphate-sensitive K channel blocker, given with flumazenil, abolished the protection obtained with the latter.

Conclusions

Flumazenil mimics preconditioning to decrease infarct size and hydroxyl radical production during reperfusion. Midazolam, however, abolishes these effects. Blockade of benzodiazepine receptors is upstream to the mitochondrial adenosine triphosphate-sensitive K channels in the preconditioning cascade.
Noninvasive, Automated and Continuous Cardiac Output Monitoring by Pulmonary Capnodynamics
Authors: Peyton Philip J. , Venkatesan Yagnaprabhu , Hood Sally G. , Junor Paul , May Clive
Published: June 2006

Background

Cardiac output monitoring is most important where cardiovascular stability is potentially threatened, such as during major surgery and in critically ill patients. However, continuous monitoring of cardiac output is still not performed routinely during anesthesia and critical care, because of invasiveness, expense, and inaccuracy of available technologies.

Methods

A technique termed the capnodynamic method was tested for breath-to-breath measurement of pulmonary blood flow from lung carbon dioxide mass balance, using measured carbon dioxide elimination and end-tidal concentration. A prototype measurement system was constructed for a feasibility study in six anesthetized sheep. Large and rapid fluctuations in cardiac output were generated by repeated dobutamine and esmolol challenge. Measurements were compared with an indwelling ultrasonic flow probe placed on the ascending aorta or pulmonary artery.

Results

Cardiac output measured by the flow probe varied between zero and 8.67 l/min, with a mean of 3.50 l/min. Overall mean bias [SD of the difference] between the methods (capnodynamic - flow probe) was -0.25 [0.94] l/min, r = 0.79 (P < 0.001). During periods of stability in cardiac output of 5 min or more, mean bias was -0.20 [0.55] l/min. The method successfully indicated two cardiac arrest events, which were induced in one of the animals.

Conclusions

The method satisfactorily tracked wide fluctuations in cardiac output in real time. The capnodynamic method may have potential for continuous noninvasive cardiac output monitoring in patients undergoing anesthesia for major surgery, and in critical care, on a routine basis.
Midazolam Inhibits Proinflammatory Mediators in the Lipopolysaccharide-activated Macrophage
Authors: Kim Seon Nyo , Son Soo Chang , Lee Sang Mook , Kim Cuk Seong , Yoo Dae Goon , Lee Sang Ki , Hur Gang Min , Park Jin Bong , Jeon Byeong Hwa
Published: June 2006

Background

Midazolam, a benzodiazepine, has a hypnotic effect and is widely used as a sedative. The role of midazolam in activation of macrophages during sepsis is not known. The aim of this study was to evaluate the antiinflammatory actions of midazolam in cultured macrophages.

Methods

Using a macrophage cell line, RAW264.7 cells, the effect of midazolam on proinflammatory mediators and activation of mitogen-activated protein kinase was measured by Western blot. Nuclear factor-kappaB (NF-kappaB) activation and translocation of p65 subunit of NF-kappaB was measured using luciferase assay and immunocytochemistry. Superoxide production was measured by lucigenin chemiluminescence.

Results

Midazolam significantly inhibited lipopolysaccharide-induced up-regulation of both cyclooxygenase 2 and inducible nitric oxide synthase in a dose-dependent manner (approximately 3-30 microm). IkappaB-alpha degradation and NF-kappaB transcriptional activity induced by lipopolysaccharide were also suppressed by the midazolam. Nuclear translocation of the p65 subunit of NF-kappaB was inhibited by midazolam. Furthermore, midazolam suppressed phosphorylation of p38 mitogen-activated protein kinase and also inhibited lipopolysaccharide-induced superoxide production in macrophages.

Conclusions

These results suggest that midazolam has an antiinflammatory action by inhibiting inducible nitric oxide synthase and cyclooxygenase-2 expression, possibly through suppression of NF-kappaB and p38 mitogen-activated protein kinase activation.
Different Brain Activation Patterns to Pain and Pain-related Unpleasantness during the Menstrual Cycle
Authors: Choi Jae Chan , Park Sang Kyu , Kim Yun-Hee , Shin Yong-Wook , Kwon Jun Soo , Kim Jin Soo , Kim Ji-Woong , Kim Soon Yul , Lee Sang Gyu , Lee Moo Sam
Published: June 2006

Background

The changes in the functional magnetic resonance imaging signal during anticipation, pain stimulation, and the poststimulation periods were investigated to determine whether changes in sex hormones affect brain activity.

Methods

Eighteen participants were examined twice, once in the follicular phase and once in the luteal phase. Half the participants were tested first during the follicular phase, and the other half were tested first in the luteal phase.

Results

The pain and unpleasantness ratings were significantly higher in the luteal phase than in the follicular. During the anticipation of pain, the prefrontal cortices were activated during the follicular phase, whereas the parahippocampal gyrus and amygdala were activated during the luteal phase. During the pain stimulation, putamen and cerebellum and precentral gyrus involving motor preparation and defense mechanism related to antinociceptive behavior were activated during the follicular phase, whereas the thalamus was activated during the luteal phase. During the poststimulation periods, the prefrontal cortices were activated during the follicular phase, whereas parahippocampal gyrus was activated during the luteal phase. The temporal pole was activated during the anticipation, pain stimulation, and poststimulation periods of the luteal phase.

Conclusions

During surgical and medical procedures, requirements of anesthetic and analgesic and anxiolytic drugs may be reduced during the follicular phase and increased during the luteal phase. These results highlight the need to consider the effects of the sex hormones in women when designing clinical or neuroimaging studies or when treating patients for pain and pain-related unpleasantness.
Effects of Bupivacaine and Tetrodotoxin on Carrageenan-induced Hind Paw Inflammation in Rats (Part 1)
Authors: Beloeil Hélène , Ababneh Zaid , Chung Richard , Zurakowski David , Mulkern Robert V. , Berde Charles B.
Published: June 2006

Background

Local anesthetics exert antiinflammatory actions. To elucidate potential mechanisms, the authors examined effects of bupivacaine or tetrodotoxin, administered to rats by ipsilateral or contralateral sciatic blockade or systemically, on carrageenan-induced hind paw hyperalgesia, edema, and stimulated cytokine production in circulating blood cells.

Methods

Twelve groups of rats (n = 9-12) received injections in three sites: (1) right or left hind paw (carrageenan or saline), (2) left sciatic block, and (3) systemically (subcutaneously in the upper back). Sciatic and systemic injections were performed with epinephrine plus bupivacaine, tetrodotoxin, or saline; injections were repeated 6 h later. Fifteen hours later, hyperalgesia and/or sensory and motor block were assessed behaviorally, and paw edema was quantified by magnetic resonance imaging. Stimulated production of tumor necrosis factor alpha, interleukin 10, and interleukin 1beta in whole blood cultures was measured by enzyme-linked immunosorbent assay.

Results

Either ipsilateral or contralateral sciatic blocks using either bupivacaine or tetrodotoxin reduced carrageenan-induced edema and hyperalgesia. Systemic bupivacaine and tetrodotoxin were ineffective in preventing edema and hyperalgesia. Bupivacaine was effective in suppressing systemic tumor necrosis factor alpha and interleukin 1beta by all three routes, whereas tetrodotoxin was ineffective by all three routes.

Conclusion

Bupivacaine and tetrodotoxin, via a contralateral or ipsilateral sciatic block, attenuate local inflammatory edema and hyperalgesia induced by hind paw injection of carrageenan in rats. Mechanisms underlying contralateral effects of sciatic blockade remain unexplained. Bupivacaine inhibits carrageenan-evoked systemic cytokine production by a mechanism not shared by tetrodotoxin; this action may involve tetrodotoxin-resistant sodium channels or a variety of non-sodium-channel targets.
Permeability of Injured and Intact Peripheral Nerves and Dorsal Root Ganglia
Authors: Abram Stephen E. , Yi Johnny , Fuchs Andreas , Hogan Quinn H.
Published: June 2006

Background

Nerve injury that produces behavioral changes of allodynia and hyperalgesia in animals is associated with electrophysiologic changes in dorsal root ganglion (DRG) cells. The introduction of drugs into the DRG or the peripheral nerve that alter calcium, sodium, or potassium channel activity may be of therapeutic benefit after nerve injury. For this reason, the authors sought to determine whether drugs that do not ordinarily cross the blood-nerve barrier will enter the DRG after intravenous or regional injection and to determine whether nerve injury alters drug access to DRGs or peripheral nerves.

Methods

Both intact and spinal nerve-ligated rats were injected with sodium fluorescein by intravenous, intrathecal, peri-DRG, perisciatic, and epidural routes. DRG, sciatic nerve, and spinal cord tissues were harvested and frozen, and histologic sections were analyzed quantitatively for tissue fluorescence.

Results

In both intact and nerve-injured animals, fluorescein accumulated in DRGs after intravenous, peri-DRG, and epidural injection. There was accumulation in the proximal portion of the ganglion after intrathecal injection. Minimal amounts of fluorescein were found in the sciatic nerve in intact animals after intravenous or perineural injection, but substantial amounts were found in some nerve fascicles in nerve-injured animals after both intravenous and perineural injection. There was almost no fluorescein found in the spinal cord except after intrathecal administration.

Conclusions

In both intact and nerve-injured animals, fluorescein accumulates freely in the DRG after intravenous, epidural, or paravertebral injection. The sciatic nerve is relatively impermeable to fluorescein, but access by either systemic or regional injection is enhanced after nerve injury.
Increased Prostaglandin E2Release and Activated Akt/β-Catenin Signaling Pathway Occur after Opioid Withdrawal in Rat Spinal Cord
Authors: Dunbar Stuart A. , Karamian Ivan , Roberts Lou , Zhang Jiahui
Published: June 2006

Background

Prostaglandin E(2) is an important spinal modulator of nociception. However, the effects of chronic opioid administration and withdrawal on prostaglandin E(2) release and associated signaling pathways in the spinal cord are generally unknown.

Methods

This study sought to examine these effects using a spinal microdialysis technique in a model of chronic morphine administration and withdrawal in the rat.

Results

The authors found that spinal prostaglandin E(2) release was unaffected by chronic morphine treatment but was significantly increased during withdrawal. Recurrent withdrawal did not further enhance this release. The authors also found up-regulation of cyclooxygenase-2 expression and phosphorylation of protein kinase Akt at Ser-473 in response to opioid withdrawal. In addition, they demonstrated that beta-catenin, a transcription factor downstream of Akt, was induced during morphine withdrawal, particularly during recurrent withdrawal.

Conclusions

These results suggest that opioid withdrawal activates signaling pathways associated with neuronal survival and transcriptional control, two processes implicated in neuronal development and synaptic plasticity.
Painful Peripheral Nerve Injury Decreases Calcium Current in Axotomized Sensory Neurons
Authors: McCallum J Bruce , Kwok Wai-Meng , Sapunar Damir , Fuchs Andreas , Hogan Quinn H.
Published: June 2006

Background

Reports of Ca(2+) current I(Ca) loss after injury to peripheral sensory neurons do not discriminate between axotomized and spared neurons. The spinal nerve ligation model separates axotomized from spared neurons innervating the same site. The authors hypothesized that I(Ca) loss is a result of neuronal injury, so they compared axotomized L5 dorsal root ganglion neurons to spared L4 neurons, as well as neurons from rats undergoing skin incision alone.

Methods

After behavioral testing, dissociated neurons from L4 and L5 dorsal root ganglia were studied in both current and voltage patch clamp modes. The biophysical consequence of I(Ca) loss on the action potential was confirmed using selective I(Ca) antagonists. Data were grouped into small, medium, and large cells for comparison.

Results

Reduced I(Ca) was predominantly a consequence of axotomy (L5 after spinal nerve ligation) and was most evident in small and medium neurons. ICa losses were associated with action potential prolongation in small and medium cells, whereas the amplitude and duration of after hyperpolarization was reduced in medium and large neurons. Blockade with Ca(2+) channel antagonists showed that action potential prolongation and after hyperpolarization diminution were alike, attributable to the loss of I(Ca).

Conclusion

Axotomy is required for I(Ca) loss. I(Ca) loss correlated with changes in the biophysical properties of sensory neuron membranes during action potential generation, which were due to I(Ca) loss leading to decreased outward Ca(2+)-sensitive K currents. Taken together, these results suggest that neuropathic pain may be mediated, in part, by loss of I(Ca) and the cellular processes dependent on Ca(2+).
Development of a Module for Point-of-care Charge Capture and Submission Using an Anesthesia Information Management System
Authors: Reich David L. , Kahn Ronald A. , Wax David , Palvia Tanuj , Galati Maria , Krol Marina
Published: June 2006

Background

The use of electronic charge vouchers in anesthesia practice is limited, and the effects on practice management are unreported. The authors hypothesized that the new billing technology would improve the effectiveness of the billing interface and enhance financial practice management measures.

Methods

A custom application was created to extract billing elements from the anesthesia information management system. The application incorporates business rules to determine whether individual cases have all required elements for a complete and compliant bill. The metrics of charge lag and days in accounts receivable were assessed before and after the implementation of the electronic charge voucher system.

Results

The average charge lag decreased by 7.3 days after full implementation. The total days in accounts receivable, controlling for fee schedule changes and credit balances, decreased by 10.1 days after implementation, representing a one-time revenue gain equivalent to 3.0% of total annual receipts. There are additional ongoing cost savings related to reduction of personnel and expenses related to paper charge voucher handling.

Conclusions

Anesthesia information management systems yield financial and operational benefits by speeding up the revenue cycle and by reducing direct costs and compliance risks related to the billing and collection processes. The observed reductions in charge lag and days in accounts receivable may be of benefit in calculating the return on investment that is attributable to the adoption of anesthesia information management systems and electronic charge transmission.
Linking ecology, behaviour and conservation: does habitat saturation change the mating system of bearded vultures?
Authors: Carrete Martina , Donázar José A , Margalida Antoni , Bertran Joan
Published: June 2006

The social organization of a population is the consequence of the decisions made by individuals to maximize their fitness, so differences in social systems may arise from differences in ecological conditions. Here, we show how a long-lived species that used to breed monogamously, and at low densities, can change its mating system in response to habitat saturation. We found that a significant proportion of unpaired birds become potential breeders by entering high-quality territories, or by forming polyandrous trios as a strategy to increase their individual performance. However, productivity of territories was reduced when those occupied by breeding pairs changed to trios, suggesting that the third individual was costly. The decision of some individuals to enter into breeding trios as subordinates also had clear negative consequences to population demography. This unusual mating behaviour is thus compromising the conservation effort directed to this endangered species; management to encourage floaters to settle in other suitable but unoccupied areas may be beneficial.
Low worldwide genetic diversity in the basking shark (Cetorhinus maximus)
Authors: Rus Hoelzel A , Shivji Mahmood S , Magnussen Jennifer , Francis Malcolm P
Published: June 2006

The basking shark (Cetorhinus maximus) is found in temperate waters throughout the world's oceans, and has been subjected to extensive exploitation in some regions. However, little is known about its current abundance and genetic status. Here, we investigate the diversity of the mitochondrial DNA control region among samples from the western North Atlantic, eastern North Atlantic, Mediterranean Sea, Indian Ocean and western Pacific. We find just six haplotypes defined by five variable sites, a comparatively low genetic diversity ofπ=0.0013 and no significant differentiation between ocean basins. We provide evidence for a bottleneck event within the Holocene, estimate an effective population size (Ne) that is low for a globally distributed species, and discuss the implications.
Acoustic acceleration waves in homentropic Green and Naghdi gases
Authors: Jordan P.M , Straughan B
Published: June 2006

Acceleration and temperature rate waves in lossless Green and Naghdi gases are investigated. The exact equations of motion are also derived and then simplified under the finite-amplitude approximation. Bounds are established for the theory-specific coupling parameter, as well as several other quantities, and results are compared/contrasted with those for classical perfect gases.
Taboo evolutionary programming: a new method of global optimization
Authors: Ji Mingjun , Klinowski Jacek
Published: June 2006

We introduce taboo evolutionary programming, a very efficient global optimization method which combines features of single-point mutation evolutionary programming (SPMEP) and taboo search. As demonstrated by solving 18 benchmark problems, the algorithm is not trapped in local minima and quickly approaches the global minimum. The results are superior to those from SPMEP, fast evolutionary programming and generalized evolutionary programming. The method is easily applicable to real-world problems, and the central idea may be introduced into other algorithms.
Steering laws for motion camouflage
Authors: Justh E.W , Krishnaprasad P.S
Published: June 2006

Motion camouflage is a stealth strategy observed in nature. We formulate the problem as a feedback system for particles moving at constant speed, and define what it means for the system to be in a state of motion camouflage. (Here, we focus on the planar setting, although the results can be generalized to three-dimensional motion.) We propose a biologically plausible feedback law, and use a high-gain limit to prove the accessibility of a motion-camouflage state in finite time. We discuss connections to work in missile guidance. We also present simulation results to explore the performance of the motion-camouflage feedback law for a variety of settings.
Revised evidence for facultative sex ratio adjustment in birds: a correction
Authors: Cassey Phillip , Ewen John G , Møller Anders P
Published: June 2006

We provide a revision to the calculation of effect sizes and heterogeneity statistics in our original article, ‘Facultative primary sex ratio variation: a lack of evidence in birds’ (

Ewen
et al
. 2004

). Our revision shows that significant heterogeneity in sex ratio study effect sizes does indeed exist and that for a series of key traits the average effect sizes (while still weak) are in fact significantly different from zero.
Global risk from extreme geophysical events: threat identification and assessment
Authors: McGuire W.J
Published: June 2006

In an increasingly interconnected world, any single geophysical hazard is capable of having consequences far beyond the range of immediate physical effects. Most recently, this was demonstrated by the 2004 Asian tsunami, which took the lives of citizens from 57 different nations, and by Hurricane Katrina in August 2005, which raised fuel prices worldwide and contributed to a record UK trade deficit in the month following the devastation of New Orleans. On an altogether wider scale, global geophysical events (GGEs) are natural phenomena capable of having wholesale deleterious consequences for the world's environment, economy and society. These may arise (i) due to a global physical effect, such as an episode of severe planetary cooling in response to a volcanic ‘super-eruption’ or large comet or asteroid impact, or (ii) as a result of subsidiary ramifications for the global economy and social fabric of a cataclysmic regional event, such as an Atlantic- or Pacific-wide ‘mega-tsunami’, or a more spatially confined event at a strategically sensitive location, for example the awaited major Tokyo earthquake. While very infrequent, the wide-ranging—and potentially ruinous—consequences of a GGE for the well-being of the international community make it essential that they are seriously considered within any comprehensive assessment of natural threats.
Lessons from the 2004 Sumatra–Andaman earthquake
Authors: Kanamori Hiroo
Published: June 2006

The 2004 Sumatra–Andaman earthquake (
M
w
=9.0–9.3) is one of the greatest earthquakes ever recorded. In terms of its physical size, it is comparable to the 1960 Chilean (
M
w
=9.5) and the 1965 Alaskan (
M
w
=9.2) earthquakes. However, the damage caused by this earthquake is far greater than that caused by other great earthquakes. The 2004 Sumatra–Andaman earthquake has been studied in great detail over broad time-scales, from a fraction of seconds to hours and months, using the modern seismic data available from global seismic networks and the Global Positioning System data. We summarize the findings obtained mainly from seismic data, and discuss the unique feature of this earthquake, and possible directions of research to minimize the impact of great earthquakes on our society.
Submarine landslides: processes, triggers and hazard prediction
Authors: Masson D.G , Harbitz C.B , Wynn R.B , Pedersen G , Løvholt F
Published: June 2006

Huge landslides, mobilizing hundreds to thousands of km
3
of sediment and rock are ubiquitous in submarine settings ranging from the steepest volcanic island slopes to the gentlest muddy slopes of submarine deltas. Here, we summarize current knowledge of such landslides and the problems of assessing their hazard potential. The major hazards related to submarine landslides include destruction of seabed infrastructure, collapse of coastal areas into the sea and landslide-generated tsunamis. Most submarine slopes are inherently stable. Elevated pore pressures (leading to decreased frictional resistance to sliding) and specific weak layers within stratified sequences appear to be the key factors influencing landslide occurrence. Elevated pore pressures can result from normal depositional processes or from transient processes such as earthquake shaking; historical evidence suggests that the majority of large submarine landslides are triggered by earthquakes. Because of their tsunamigenic potential, ocean-island flank collapses and rockslides in fjords have been identified as the most dangerous of all landslide related hazards. Published models of ocean-island landslides mainly examine ‘worst-case scenarios’ that have a low probability of occurrence. Areas prone to submarine landsliding are relatively easy to identify, but we are still some way from being able to forecast individual events with precision. Monitoring of critical areas where landslides might be imminent and modelling landslide consequences so that appropriate mitigation strategies can be developed would appear to be areas where advances on current practice are possible.
Managing extreme natural disasters in coastal areas
Authors: Kesavan P.C , Swaminathan M.S
Published: June 2006

Extreme natural hazards, particularly the hydro-meteorological disasters, are emerging as a cause of major concern in the coastal regions of India and a few other developing countries. These have become more frequent in the recent past, and are taking a heavy toll of life and livelihoods. Low level of technology development in the rural areas together with social, economic and gender inequities enhance the vulnerability of the largely illiterate, unskilled, and resource-poor fishing, farming and landless labour communities. Their resilience to bounce back to pre-disaster level of normality is highly limited. For the planet Earth at crossroads, the imminent threat, however, is from a vicious spiral among environmental degradation, poverty and climate change-related natural disasters interacting in a mutually reinforcing manner. These, in turn, retard sustainable development, and also wipe out any small gains made thereof. To counter this unacceptable trend, the M.S. Swaminathan Research Foundation has developed a biovillage paradigm and rural knowledge centres for ecotechnological and knowledge empowerment of the coastal communities at risk. Frontier science and technologies blended with traditional knowledge and ecological prudence result in ecotechnologies withpro-nature,pro-poorandpro-womenorientation. The rural communities are given training and helped to develop capacity to adopt ecotechnologies for market-driven eco-enterprises. The modern information and communication-based rural knowledge centres largely operated by trained semi-literate young women providetime- andlocale-specificinformation on weather, crop and animal husbandry, market trends and prices for local communities, healthcare, transport, education, etc. to the local communities. The ecotechnologies and time- and locale-specific information content development are need-based and chosen in a ‘bottom-up’ manner. The use of recombinant DNA technology for genetic shielding of agricultural crops for coastal regions against abiotic stress (induced by the water- and weather-related natural disasters), strengthens the foundations of sustainable agriculture undertaken by the resource-poor small farm families.
Convective discretization schemes for the turbulence transport equations
in flow predictions through sharp u‐bends
Authors: Bo T. , Iacovides H. , Launder B.E.
Published: June 2006

This paper presents finite volume computations of turbulent flow through
a square cross‐sectioned U‐bend of curvature strong enough
(Rc/D =0.65) to cause separation. A zonal turbulence
modelling approach is adopted, in which the high‐Re k‐ε
model is used over most of the flow domain with the low‐Re,
I‐equation model of k‐transport employed within the
near‐wall regions. Computations with grids of different sizes and
also with different discretization schemes, demonstrate that for this flow
the solution of the k and ε equations is more sensitive to the
scheme employed in their convective discretization than the solution of the
mean flow equations. To avoid the use of extremely fine 3‐Dimensional
grids, bounded high order schemes need to be used in the discretization of
the turbulence transport equations. The predictions, while encouraging,
displayed some deficiencies in the downstream region due to deficiencies in
the turbulence model. Evidently, further refinements in the turbulence model
are necessary. Initial computations of flow and heat transfer through a
rotating U‐bend, indicate that at rotational numbers (Ro =
ΩD/Wb) relevant to blade cooling passages, the
Coriolis force can substantially modify the hydrodynamic and thermal
behaviour.
A locally modified second order upwind scheme for convection terms
discretization
Authors: Papadakis G. , Bergeles G.
Published: June 2006

A finite difference scheme for convection term discretization, called
BSOU (stands for Bounded Second Order Upwind), is developed and its
performance is assessed against exact or benchmark solutions in linear and
non‐linear cases. It employs a flux blending technique between first
order upwind and second order upwind schemes only in those regions of the
flow field where spurious oscillations are likely to occur. The blending
factors are calculated with the aid of the convection boundedness criterion.
In all cases the scheme performed very well, minimizing the numerical
diffusion errors. The scheme is transportive, conservative, bounded, stable
and accurate enough so as to be suitable for inclusion into a general purpose
solution algorithm.
A well‐behaved scheme to model strong convection in a general
transport equation
Authors: Pascau A. , Pérez C. , Sánchez D.
Published: June 2006

A new discretization scheme named NOTABLE (New Option for
the Treatment of Advection in the Boundary Layer Equations) is
presented. Despite its name, this scheme is intended to be used in a general
transport equation to discretize the convective term. It is formally
third‐order accurate in regions of smooth solution and
first‐order accurate at grid points having local maxima. Within the
finite‐volume formulation it relates the face values to the nodal
values via a non‐linear function. This scheme has been compared with
well‐known high‐order schemes like QUICK and it has always
given more accurate solutions. After assessing the scheme in several
unidimensional test cases for which an exact solution is available, its
performance in a complex swirling flow is addressed.
Euler calculations of diffuser flow field, free jets and impinging
jets
Authors: Mehta R.C. , Pandya M.J. , Jayachandran T.
Published: June 2006

Under‐ and over‐expanded jet flows are calculated for the
Euler equations. The solution procedure is based on the two‐stage
Runge‐Kutta time‐stepping scheme. The studies of the flow field
structure in diffusers, free jets and impinging jets have been investigated
for a range of jet‐to‐stream total pressure ratios and for
different exit Mach numbers. The resulting flows show a complex
shock‐shear expansion structure with Mach discs. Numerical results are
compared with available experimental data and with previously published data.
An oscillating phenomenon was observed in the case of free jets operating at
sonic exit Mach number and in another case of impingement of
under‐expanded jets on a flat plate.
An efficient bem solution for three‐dimensional transient heat
conduction
Authors: Gupta Anil , Sullivan John M. , Delgado Hugo E.
Published: June 2006

This paper presents a computationally efficient numerical solution
scheme to solve transient heat conduction problems using the boundary element
method (BEM) without volume discretization. Traditionally, a
transient solution using BEM is very computer intensive due to the
excessive numerical integration requirements at each time increment. In the
present work a numerical solution scheme based on the separation of time and
space integrals in the boundary integral equation through the use of an
appropriate series expansion of the integrand (incomplete gamma
function) is presented. The space integrals are evaluated only once in
the beginning and within each time increment the additional integrals are
obtained from the previously evaluated space integrals by a simple
calculation. Three‐dimensional applications are provided to compare
the proposed strategy with that used traditionally. The CPU requirements are
reduced substantially. The solution scheme presented allows for dynamically
changing the time step size as the solution evolves. This feature is not
practical in the traditional schemes based on boundary discretization
only.
Transient conjugated heat transfer in concentric annuli
Authors: El‐Shaarawi M.A.I. , Al‐Nimr M.A. , Hader M.A.
Published: June 2006

The paper presents a finite‐difference scheme to solve the
transient conjugated heat transfer problem in a concentric
annulus with simultaneously developing hydrodynamic and thermal
boundary layers. The annular forced flow is laminar with
constant physical properties. Thermal transient is initiated by
a step change in the prescribed isothermal temperature of the
inner surface of the inside tube wall while the outer surface of
the external tube is kept adiabatic. The effects of solid‐fluid
conductivity ratio and diffusivity ratio on the thermal
behaviour of the flow have been investigated. Numerical results
are presented for a fluid of Pr = 0.7 flowing in an
annulus of radius ratio 0.5 with various values of inner and
outer solid wall thicknesses.
A numerical simulation of measured transient heat transfer through a
concrete ground floor slab and underlying substrata
Authors: Rees S.W. , Lloyd R.M. , Thomas H.R.
Published: June 2006

This paper presents the results of a numerical simulation of measured
heat losses from a real building. In particular, the thermal response of a
concrete ground floor slab and the underlying foundation soils has been
analysed and the results calibrated against data acquired from a
comprehensive long term in‐situ monitoring experiment. A numerical solution
of a heat conduction model is obtained by use of the finite element method.
Finite differences are used to accommodate the time varying nature of the
problem. The model has been applied to the simulation of transient
one‐dimensional behaviour. Diurnal and seasonal variations in temperature are
considered. Good correlation between predicted and measured thermal response
has been achieved. It is, therefore, claimed that the modelling approach
adopted is capable of representing real in‐situ behaviour.
Chebyshev series solution for radiative transport in a medium with a
linearly anisotropic scattering phase function
Authors: Laclair T. , Frankel J.I.
Published: June 2006

One‐dimensional radiative heat transfer is considered in a
plane‐parallel geometry for an absorbing, emitting, and linearly anisotropic
scattering medium subjected to azimuthally symmetric incident radiation at
the boundaries. The integral form of the transport equation is used
throughout the analysis. This formulation leads to a system of
weakly‐singular Fredholm integral equations of the second kind. The resulting
unknown functions are then formally expanded in Chebyshev series. These
series representations are truncated at a specified number of terms, leaving
residual functions as a result of the approximation. The collocation and the
Ritz‐Galerkin methods are formulated, and are expressed in terms of general
orthogonality conditions applied to the residual functions. The major
contribution of the present work lies in developing quantitative error
estimates. Error bounds are obtained for the approximating functions by
developing equations relating the residuals to the errors and applying
functional norms to the resulting set of equations. The collocation and
Ritz‐Galerkin methods are each applied in turn to determine the expansion
coefficients of the approximating functions. The effectiveness of each method
is interpreted by analyzing the errors which result from the
approximations.
Numerical visualization of convective heat transfer from a sphere — with
and without radial mass efflux
Authors: Chattopadhyay Himadri , Dash Sukanta K.
Published: June 2006

The conception of a heat function, just like the stream function used in
a laminar two dimensional incompressible flow field visualization, has been
introduced to visualize the convective heat transfer or the flow of energy
around a sphere when the sphere is either being cooled or heated by a stream
of fluid flowing around it. The heat function is developed in a spherical
polar coordinate and is used to generate the heat lines around the sphere.
The heat lines essentially show the magnitude and direction of energy
transfer around the sphere with and without the existence of a finite radial
velocity at the surface. The steady state hydrodynamic field around the
sphere is numerically obtained up to a maximum Reynolds number of 100 and the
corresponding thermal field has been obtained by solving the steady state
energy equation. The field properties thus obtained are utilized to form the
heat function, which becomes an effective tool for visualization of
convective heat transfer.
Accuracy analysis of central schemes with artificial dissipation and
upwind flux‐difference tvd schemes for navier‐stokes equations
Authors: Dick E. , Steelant J.
Published: June 2006

A comparison of the accuracy of the central discretization scheme with
artificial dissipation and the upwind flux‐difference TVD scheme has been
made for the compressible Navier‐Stokes equations for high Reynolds number
flows. First, a comparison is made on two one‐dimensional model problems.
Then the schemes are compared on flat plate boundary layer flow. It is shown
that a central scheme basically has poor accuracy due to the isotropic nature
of the artificial dissipation. An upwind scheme decomposes the flow into
different components and adapts the dissipation to the velocity of the
components. The associated ansitropic dissipation results in a good accuracy.
It is further discussed how a central discretization scheme with artificial
dissipation can be improved at the expense of the same complexity of an
upwind scheme.