bluuebunny/crossref_metadata_2025 huggingface dataset:
Methods and technologies to improve efficiency of water use
Authors: Evans Robert G. , Sadler E. John
Published: July 2008

The competition for existing freshwater supplies will require a paradigmatic shift from maximizing productivity per unit of land area to maximizing productivity per unit of water consumed. This shift will, in turn, demand broad systems approaches that physically and biologically optimize irrigation relative to water delivery and application schemes, rainfall, critical growth stages, soil fertility, location, and weather. Water can be conserved at a watershed or regional level for other uses only if evaporation, transpiration, or both are reduced and unrecoverable losses to unusable sinks are minimized (e.g., salty groundwater or oceans). Agricultural advances will include implementation of crop location strategies, conversion to crops with higher economic value or productivity per unit of water consumed, and adoption of alternate drought‐tolerant crops. Emerging computerized GPS‐based precision irrigation technologies for self‐propelled sprinklers and microirrigation systems will enable growers to apply water and agrochemicals more precisely and site specifically to match soil and plant status and needs as provided by wireless sensor networks. Agriculturalists will need to exercise flexibility in managing the rate, frequency, and duration of water supplies to successfully allocate limited water and other inputs to crops. The most effective means to conserve water appears to be through carefully managed deficit irrigation strategies that are supported by advanced irrigation system and flexible, state‐of‐the‐art water delivery systems. Nonagricultural water users will need to exercise patience as tools reflecting the paradigmatic shift are actualized. Both groups will need to cooperate and compromise as they practice more conservative approaches to freshwater consumption.
Numerical analysis of buoyancy effects during the dissolution and transport of oxygenated gasoline in groundwater
Authors: Molson J. , Mocanu M. , Barker J.
Published: July 2008

Dissolution of oxygenated gasoline, as well as buoyancy‐driven groundwater flow and transport of the multicomponent dissolved phase plumes, is simulated numerically in three dimensions. The simulations are based on a field experiment described by Mocanu (2007) in which three oxygenated gasoline sources were emplaced as nonaqueous phase liquids (NAPLs) below the water table of the shallow sand aquifer at Canadian Forces Base Borden, Ontario. The sources were composed of an ethanol‐free gasoline mixture spiked with 9.8% methyl tert‐butyl ether and 0.2% tert‐butyl alcohol (GMT‐E0), a gasoline with 10% ethanol (E10), and a source with 95% ethanol (E95). The numerical model includes dissolution of gasoline as a NAPL, density‐dependent groundwater flow, advective‐dispersive transport of the dissolved components, and ethanol cosolvency and degradation. Buoyancy effects in the dissolved plumes were compared under a homogeneous hydraulic conductivity field as well as with five realizations of spatially correlated random fields representing the Borden aquifer. The simulations showed that buoyancy was most significant in the E95 source plumes within the homogeneous system, having induced after 150 days a net upward displacement of the local peak concentrations for all but the least soluble component of approximately 1.5 m. The peak rise in ethanol from the GMT‐E0 and E10 plumes was about 0.6 m. The results highlight the importance of shallow monitoring wells when monitoring high oxygenate fraction gasoline spills in groundwater and have implications for assessing mass fluxes and biodegradation rates.
Significance of the concentration gradients associated with dunite bodies in the Josephine and Trinity ophiolites
Authors: Morgan Zachary , Liang Yan , Kelemen Peter
Published: July 2008

Detailed transects were sampled across dunite bodies in the Josephine and Trinity ophiolites. The major peridotite lithologies sampled in the Josephine transect are a sequence of dunite and harzburgite and in the Trinity transect a sequence of dunite, harzburgite, lherzolite, and plagioclase lherzolite (DHL‐PL). Major, minor, and selected trace element abundances in olivine, orthopyroxene, clinopyroxene, and spinel were measured. The composition profile from the Josephine transect has revealed a concentration gradient near the dunite‐harzburgite contact. The composition profile from the Trinity transect has revealed several concentration gradients: two within the dunite, one in the harzburgite, and at least two in the plagioclase lherzolite. The composition profiles record complex histories of melt transport, melt‐rock reaction, and subsequent subsolidus reequilibration. Analyses of closure distance suggest that compositional variation trends for a majority of major and minor elements in olivine, clinopyroxene, orthopyroxene, and spinel reported in this study were magmatic in origin. Subsolidus reequilibration may reduce the range or magnitude of variations for the 2+ cations such as Fe and Mg in olivine and spinel and significantly redistribute Ca and Li in coexisting minerals. Numerical simulations exploring the coupling of diffusion and advection in a porous matrix were used to explain compositional variations across the peridotite sequences. Melt flow from the host harzburgite into the dunite produces composition gradients near the dunite‐harzburgite contacts similar to those from the Josephine transect. In contrast, melt flow from the dunite into the surrounding peridotite lithologies can produce concentration gradients similar to those observed in the Trinity transect. At least two chemically distinct episodes of melt flow within the same dunite channel system are proposed. Results from this study show that concentration gradients developed around the dunite‐harzburgite and DHL‐PL sequences can be used to infer part of the melt flow history of the dunite channel systems in the mantle. Results from this study and those from other ophiolite studies also demonstrate that concentration profiles in dunite and the surrounding peridotite lithologies are highly variable even among differing peridotite sequences within the same ophiolite, suggesting that the composition of instantaneous melt flowing through individual dunite channels is quite variable and the mantle source regions are heterogeneous.
A 1,000‐year, annually‐resolved record of hurricane activity from Boston, Massachusetts
Authors: Besonen Mark R. , Bradley Raymond S. , Mudelsee Manfred , Abbott Mark B. , Francus Pierre
Published: July 2008

The annually‐laminated (i.e., varved) sediment record from the Lower Mystic Lake (near Boston, MA), contains a series of anomalous graded beds deposited by strong flooding events that have affected the basin over the last millennium. From the historic portion of the record, 10 out of 11 of the most prominent graded beds correspond with years in which category 2–3 hurricanes are known to have struck the Boston area. Thus, we conclude that the graded beds represent deposition related to intense hurricane precipitation combined with wind‐driven vegetation disturbance that exposes fresh, loose sediment. The hurricane signal shows strong, centennial‐scale variations in frequency with a period of increased activity between the 12th–16th centuries, and decreased activity during the 11th and 17th–19th centuries. These frequency changes are consistent with other paleoclimate indicators from the tropical North Atlantic, in particular, sea surface temperature variations.
Rare measurements of a sprite with halo event driven by a negative lightning discharge over Argentina
Authors: Taylor M. J. , Bailey M. A. , Pautet P. D. , Cummer S. A. , Jaugey N. , Thomas J. N. , Solorzano N. N. , Sao Sabbas F. , Holzworth R. H. , Pinto O. , Schuch N. J.
Published: July 2008

As part of a collaborative campaign to investigate Transient Luminous Events (TLEs) over South America, coordinated optical, ELF/VLF, and lightning measurements were made of a mesoscale thunderstorm observed on February 22–23, 2006 over northern Argentina that produced 445 TLEs within a ∼6 hour period. Here, we report comprehensive measurements of one of these events, a sprite with halo that was unambiguously associated with a large negative cloud‐to‐ground (CG) lightning discharge with an impulsive vertical charge moment change (ΔMQv) of −503 C.km. This event was similar in its location, morphology and duration to other positive TLEs observed from this storm. However, the downward extent of the negative streamers was limited to 25 km, and their apparent brightness was lower than that of a comparable positive event. Observations of negative CG events are rare, and these measurements provide further evidence that sprites can be driven by upward as well as downward electric fields, as predicted by the conventional breakdown mechanism.
Electron firehose instability: Kinetic linear theory and two‐dimensional particle‐in‐cell simulations
Authors: Camporeale Enrico , Burgess David
Published: July 2008

The kinetic electron firehose instability (EFI) is thought to be a crucial mechanism for constraining the observed electron anisotropy in expanding astrophysical plasmas, such as the solar wind. The EFI arises in a bi‐Maxwellian plasma when the parallel temperature is greater than the perpendicular one, and its effect is to reduce anisotropy. We study this mechanism via kinetic linear theory, extending and refining previous results, and by new two‐dimensional particle‐in‐cell (PIC) simulations with physical mass ratio. The results of PIC simulations show under which conditions the EFI can indeed be regarded as a constraint for electron distribution function. The detailed electron physics near marginal stability condition is discussed, with emphasis on the competition between growing and damping modes and on wave patterns formed at the nonlinear stage. The results also suggest an observational signature that the EFI has operated, namely the appearance of low‐frequency, quasiperpendicular whistler/electron–cyclotron waves.
El Niño–Southern Oscillation–like variability during glacial terminations and interlatitudinal teleconnections
Authors: Pena L. D. , Cacho I. , Ferretti P. , Hall M. A.
Published: July 2008

Interannual‐decadal variability in the equatorial Pacific El Niño–Southern Oscillation (ENSO) induces climate changes at global scale, but its potential influence during past global climate change is not yet well constrained. New high‐resolution eastern equatorial Pacific proxy records of thermocline conditions present new evidence of strong orbital control in ENSO‐like variability over the last 275,000 years. Recurrent intervals of saltier thermocline waters are associated with the dominance of La Niña–like conditions during glacial terminations, coinciding with periods of low precession and high obliquity. The parallel dominance of δ13C‐depleted waters supports the advection of Antarctic origin waters toward the tropical thermocline. This “oceanic tunneling” is proposed to have reinforced orbitally induced changes in ENSO‐like variability, composing a complex high‐ and low‐latitude feedback during glacial terminations.
International Life Sciences Institute (Health and Environmental Sciences Institute, HESI) initiative on moving towards better predictors of drug‐induced torsades de pointes
Authors: Bass A S , Darpo B , Breidenbach A , Bruse K , Feldman H S , Garnes D , Hammond T , Haverkamp W , January C , Koerner J , Lawrence C , Leishman D , Roden D , Valentin J P , Vos M A , Zhou Y‐Y , Karluss T , Sager P
Published: July 2008

Knowledge of the cardiac safety of emerging new drugs is an important aspect of assuring the expeditious advancement of the best candidates targeted at unmet medical needs while also assuring the safety of clinical trial subjects or patients. Present methodologies for assessing drug‐induced torsades de pointes (TdP) are woefully inadequate in terms of their specificity to select pharmaceutical agents, which are human arrhythmia toxicants. Thus, the critical challenge in the pharmaceutical industry today is to identify experimental models, composite strategies, or biomarkers of cardiac risk that can distinguish a drug, which prolongs cardiac ventricular repolarization, but is not proarrhythmic, from one that prolongs the QT interval and leads to TdP. To that end, the HESI Proarrhythmia Models Project Committee recognized that there was little practical understanding of the relationship between drug effects on cardiac ventricular repolarization and the rare clinical event of TdP. It was on that basis that a workshop was convened in Virginia, USA at which four topics were introduced by invited subject matter experts in the following fields: Molecular and Cellular Biology Underlying TdP, Dynamics of Periodicity, Models of TdP Proarrhythmia, and Key Considerations for Demonstrating Utility of Pre‐Clinical Models. Contained in this special issue of the British Journal of Pharmacology are reports from each of the presenters that set out the background and key areas of discussion in each of these topic areas. Based on this information, the scientific community is encouraged to consider the ideas advanced in this workshop and to contribute to these important areas of investigations over the next several years.

British Journal of Pharmacology (2008) 154, 1491–1501; doi:fn8
Induction of BAG2 protein during proteasome inhibitor‐induced apoptosis in thyroid carcinoma cells
Authors: Wang H‐Q , Zhang H‐Y , Hao F‐J , Meng X , Guan Y , Du Z‐X
Published: July 2008

Background and purpose:

Proteasome inhibitors exhibit cytotoxic against tumours of different histology. However, the mechanism of apoptosis induction by these compounds remains unclear and is likely to be a complex cascade of events. Bcl‐2‐associated athanogene (BAG) family proteins are characterized by their property of interaction with a variety of partners involved in modulating the proliferation/death balance, including heat shock proteins (HSP), Bcl‐2, Raf‐1. The role of BAG family proteins in proteasome inhibition has not been elucidated.

Experimental approach:

Effects of proteasome inhibitors on BAG2 expression were evaluated using real‐time reverse transcription‐polymerase chain reaction (RT‐PCR). BAG2 expression was knocked down by small interfering RNAs (siRNA). Cell death was evaluated using Annexin V/propidium iodide staining and subsequent FACS.

Key results:

The proteasome inhibitors, MG132, PSI, lactacystin and epoxomicin, induced BAG2 at the transcriptional level. MG132‐induced apoptosis was significantly suppressed by BAG2 knockdown using RNA interference.

Conclusions and implications:

Our results suggest that BAG2 is a novel molecule induced by proteasome inhibition, which exhibits a pro‐apoptotic property in death of thyroid cancer cells induced by proteasome inhibition.

British Journal of Pharmacology (2008) 155, 655–660; doi:10.1038/bjp.2008.302; published online 28 July 2008
Neuroprotection in Diet-Induced Ketotic Rat Brain after Focal Ischemia
Authors: Puchowicz Michelle A , Zechel Jennifer L , Valerio Jose , Emancipator Douglas S , Xu Kui , Pundik Svetlana , LaManna Joseph C , Lust W David
Published: July 2008

Neuroprotective properties of ketosis may be related to the upregulation of hypoxia inducible factor (HIF)-1α, a primary constituent associated with hypoxic angiogenesis and a regulator of neuroprotective responses. The rationale that the utilization of ketones by the brain results in elevation of intracellular succinate, a known inhibitor of prolyl hydroxylase (the enzyme responsible for the degradation of HIF-1α) was deemed as a potential mechanism of ketosis on the upregulation of HIF-1α. The neuroprotective effect of diet-induced ketosis (3 weeks of feeding a ketogenic diet), as pretreatment, on infarct volume, after reversible middle cerebral artery occlusion (MCAO), and the upregulation of HIF-1α were investigated. The effect of β-hydroxybutyrate (BHB), as a pretreatment, via intraventricular infusion (4 days of infusion before stroke) was also investigated following MCAO. Levels of HIF-1α and Bcl-2 (anti-apoptotic protein) proteins and succinate content were measured. A 55% or 70% reduction in infarct volume was observed with BHB infusion or diet-induced ketosis, respectively. The levels of HIF-1α and Bcl-2 proteins increased threefold with diet-induced ketosis; BHB infusions also resulted in increases in these proteins. As hypothesized, succinate content increased by 55% with diet-induced ketosis and fourfold with BHB infusion. In conclusion, the biochemical link between ketosis and the stabilization of HIF-1α is through the elevation of succinate, and both HIF-1α stabilization and Bcl-2 upregulation play a role in ketone-induced neuroprotection in the brain.
Preparation, Clinical Support, and Confidence of Speech-Language Pathologists Managing Clients With a Tracheostomy in Australia
Authors: Ward Elizabeth , Agius Emma , Solley Maura , Cornwell Petrea , Jones Claire
Published: July 2008

Purpose

To describe the preparation and training, clinical support, and confidence of speech-language pathologists (SLPs) in relation to tracheostomy client care in Australia.

Method

A survey was sent to 90 SLPs involved in tracheostomy management across Australia. The survey contained questions relating to preparation and training, clinical support, and confidence.

Results

The response rate was high (76%). The majority of SLPs were pursuing a range of professional development activities, had clinical support available, and felt confident providing care of clients with tracheostomies. Despite these findings, 45% of SLPs were not up-to-date with evidence-based practice, less than 30% were knowledgeable of the advances in tracheostomy tube technology, and only 16% felt they worked as part of an optimal team. Only half were confident and had clinical support for managing clients who were ventilated. Most (88%) believed additional training opportunities would be beneficial.

Conclusions

The current data highlight issues for health care facilities and education providers to address regarding the training and support needs of SLPs providing tracheostomy client care.
Principles of Motor Learning in Treatment of Motor Speech Disorders
Authors: Maas Edwin , Robin Donald A. , Austermann Hula Shannon N. , Freedman Skott E. , Wulf Gabriele , Ballard Kirrie J. , Schmidt Richard A.
Published: July 2008

Purpose

There has been renewed interest on the part of speech-language pathologists to understand how the motor system learns and determine whether principles of motor learning, derived from studies of nonspeech motor skills, apply to treatment of motor speech disorders. The purpose of this tutorial is to introduce principles that enhance motor learning for nonspeech motor skills and to examine the extent to which these principles apply in treatment of motor speech disorders.

Method

This tutorial critically reviews various principles in the context of nonspeech motor learning by reviewing selected literature from the major journals in motor learning. The potential application of these principles to speech motor learning is then discussed by reviewing relevant literature on treatment of speech disorders. Specific attention is paid to how these principles may be incorporated into treatment for motor speech disorders.

Conclusions

Evidence from nonspeech motor learning suggests that various principles may interact with each other and differentially affect diverse aspects of movements. Whereas few studies have directly examined these principles in speech motor (re)learning, available evidence suggests that these principles hold promise for treatment of motor speech disorders. Further research is necessary to determine which principles apply to speech motor (re)learning in impaired populations.
Anesthetic Implications for Patients With Implantable Cardioverter Defibrillators
Authors: Haddow Gordon R. , Neville Michael
Published: July 2008

Implantable cardioverter defibrillators have become one of the preferred methods for treating many life- threatening ventricular arrhythmias. Many tens of thou sands of these devices have been implanted and this, together with the ease of worldwide travel, has made it more likely that anesthesiologists everywhere may come into contact with these patients either for elective or emergency surgery. These patients present unique anesthetic challenges because of the combination of the device and severe underlying cardiac disease. This article presents an overview of the implantable defibril lator as it affects the anesthesiologist, including device function, device assessment, electromagnetic interfer ence, and perioperative management.
How Does One Safely Anesthetize a Univentricular Patient for Noncardiac Surgery?
Authors: Tebich Susan
Published: July 2008

As the surgical, perioperative, and pediatric management of univentricular patients advances, more anesthesiologists will see these challenging patients as children, teenagers, and adults come to the operating room for common noncar diac surgeries: tonsillectomy, appendectomy, labor and de livery, etc. The univentricular heart has 2 atrioventricular valves with 1 ventricular chamber or a large dominant ven tricle associated with a diminutive opposing ventricle. The common pathway of physiology is complete mixing of blood. Blood pressure and oxygen saturation are dependent on the ratio of pulmonary vascular resistance (PVR) to sys temic vascular resistance (SVR). A thorough history and physical examination give the anesthesiologist insight into what further laboratory evaluations and interventions are needed. The 3 key issues with respect to echocardiographic evaluation of the heart are ventricular function, atrioventric ular valve insufficiency, and pulmonary artery stenosis or distortion. After completion of the ventricular bypass proce dures, the hemodynamics rely on the homeostasis of the PVR/SVR ratio, ventricular performance, and oxygen deliv ery. Therefore, the univentricular physiology is best served by spontaneous ventilation. Intraoperative and postopera tive pain management is key to facilitating extubation of the patient's trachea and subsequently expediting recovery from surgery.
Anesthetic Management of Pediatric Cardiac Transplantation
Authors: Applegate Richard L. , Mason Linda J. , Thompson Teresa L.
Published: July 2008

Cardiac transplantation has become a widely accepted ther apy for a variety of end-stage cardiac diseases in pediatric patients. From November 1985 to November 1999, 347 pe diatric cardiac transplantations were performed at Loma Linda University Medical Center (LLUMC), including 235 in children younger than 6 months of age. It is essential to be familiar with the physiologic and anatomic characteristics of the recipient. Hypoplastic left heart syndrome is the most frequent congenital disorder leading to transplant in neo nates at LLUMC, with diseases presenting with left ventric ular failure accounting for the majority of the remainder of patients. We have assessed many variables for a possible relationship to intraoperative or postoperative compli cations, including anesthetic induction and maintenance agents, pH and base excess, as determined by arterial blood gas analysis before cardiopulmonary bypass (CPB), and he modynamic changes requiring treatment before CPB. Al though we have noticed an association between low patient temperature or mechanical stimulation at the time of ster notomy, and hemodynamic complications before CPB, in our experience no single anesthetic technique or intraoper ative event, including ventricular fibrillation, predicts early mortality. We believe anesthetic management of pediatric cardiac transplant recipients should be tailored to fit the pathophysiology present.
Eisenmenger Syndrome
Authors: Previte Joseph , Haran Panchapakesan
Published: July 2008

The incidence of congenital cardiovascular malformation is unknown but is estimated to be approximately 0.8% of live births. This figure does not include preterm infants (all of whom have a patent ductus arteriosus [PDA]) or stillborn infants (who have a high incidence of cardiovascular abnor malities). Approximately 9% of patients with congenital car diac disease and 11% of those with uncorrected left-to-right intracardiac shunts will develop the Eisenmenger syndrome (ES). ES develops at different rates, depending on the size and location of the cardiac lesion and the amount of in creased pulmonary blood flow and pressure. Onset in in fancy is common in patients with PDA or a large ventricular septal defect (VSD). ES is seen in up to 50% of patients with VSD larger than 1.5 cm in diameter, whereas there is only a 3% incidence in those with defects that are less than 1.5 cm in diameter. Children with Down syndrome and a VSD or atrioventricular canal defect are prone to early development of ES. They have abnormal upper airways that predispose them to chronic upper airway obstruction and sleep apnea, both of which promote hypoxemia, hypercarbia, and early development of pulmonary hypertension. ES develops early in nearly all patients with uncorrected transposition of the great arteries and truncus arteriosus, whereas most patients with uncorrected ASD who develop the syndrome do so in the second decade of life. The prognosis for survival through childhood with ES is relatively good. Patients usually lead remarkably active lives until shortly before they die. The goal of this article is to provide a detailed overview of the pathophysiology, clinical presentation, and medical and sur gical management of these patients. Particular focus on the anesthetic management of patients undergoing cardiac and noncardiac surgery is provided.
Diagnosis and Management of Arrhythmias in Children After Cardiac Surgery
Authors: Botero Monica , Davies Laurie K.
Published: July 2008

Arrhythmias that lead to hemodynamic deterioration and sudden death are one of the most challenging problems in children after cardiac surgery. In infants with congenital heart disease, disorders of impulse conduction are more frequent than those of impulse generation. Various factors that include anatomic or physiologic abnormalities of the conduction system, damage as a result of hemodynamic stress or chronic hypoxia, and injury occurring at the time of surgery interact to produce dysrhythmias. During the post operative period, supraventricular tachycardia rarely causes sudden death in children. However, junctional ectopic tachy cardia and Wolff-Parkinson-White syndrome are 2 that have been associated with a high mortality rate. In general, ven tricular tachycardia carries a more serious prognosis than supraventricular tachycardia because it typically occurs in abnormal myocardium with suboptimal function, which may also be vulnerable to degeneration into ventricular fi brillation. A practical approach to the most common intra operative and postoperative arrhythmias in pediatric cardiac patients is discussed. Patients at risk, the types of arrhyth mias likely to occur after specific cardiac operations, and the most effective current therapies are reviewed.
Pediatric Cardiac Electrophysiology
Authors: Arciaga Peregrina L. , Johnson Calvin
Published: July 2008

The rapid development of invasive cardiac electrophysi ologic procedures, including the insertion of rate-responsive pacemakers, radiofrequency catheter ablation (RFA), and the implantation of cardiac defibrillators has given pediatric cardiac electrophysiologists better techniques to treat in fants and children with arrhythmias. Expertise on the basic pathophysiologic mechanisms of arrhythmias is a requisite in performing invasive intracardiac electrophysiologic pro cedures. Techniques for invasive cardiac electrophysiologic procedures (EPS) in pediatric patients are similar to those for diagnostic cardiac catheterization. The choice of anes thesia is determined by institutional preference, patient's age, anticipated sites of intravascular access, and type of procedure. The goal is to avoid agents that depress myocar dial contractility or affect cardiac conduction or refractori ness. EPS equipment includes multielectrode catheters, a multichannel recording system, an electrical stimulator, and a fluoroscopy unit. EPS require the ability to induce, termi nate, and modify cardiac arrhythmias. The objectives of the EPS include definition of the mechanisms of observed and induced cardiac arrhythmias, determination of risk for sudden cardiac arrhythmic death, investigation of antiar rhythmic drug efficacy, and ablation of tachyarrhythmia sub strates. This is accomplished by evaluating electrophysi ologic properties, such as automaticity, conduction, and refractoriness; by initiating and terminating tachycardias; by mapping sequence of activation; and by evaluating patients for various forms of therapy and judging the response to therapy. Though generally quite low, the associated morbid ity and mortality in performing EP study and RFA in pediatric patients varies considerably, depending on the patient's age and size, diagnosis, associated cardiac defects, and prepro cedure condition.
Optimal Conditions for Cardiopulmonary Bypass
Authors: Cook David J.
Published: July 2008

There is no single optimal set of conditions for cardio pulmonary bypass. What is optimal is determined by patient factors, surgical need, and the mechanics of perfusion. Additionally, the best way to manage bypass typically varies over its course.
Platelet Function and Cardiopulmonary Bypass
Authors: Samson Shari , Shore-Lesserson Linda
Published: July 2008

Cardiopulmonary bypass (CPB) is a nonphysiologic state that has many detrimental effects on a patient's hemostatic integrity. Exposure to the extracorporeal circuit and subsequent activation of the coagulation and fibrinolytic systems are factors that contribute to morbidity and mortality in cardiac surgical patients. These effects can be prevented in part or appropriately treated if practitioners understand the basic mecha nisms. This article reviews the effects of CPB on platelet function, the relationship of platelet function to post operative bleeding, the monitors available to measure platelet function, and the impact of antiplatelet therapy on bleeding in cardiac surgery.
Adverse Central Nervous System Outcomes After Cardiopulmonary Bypass: A Beneficial Effect of Aprotinin?
Authors: Murkin John M.
Published: July 2008

This review considers the evidence for potential central nervous system benefits associated with use of anti- protease therapy for patients undergoing procedures involving cardiopulmonary bypass. Unfortunately, few randomized, controlled clinical trials have assessed the lysine analogue class of antifibrinolytics (ie, ∈-amino caproic acid, tranexamic acid) compared with the num ber investigating the efficacy of the enzyme-inactivator class of antifibrinolytic typified by the nonspecific serine protease inhibitors aprotinin and nafamostat.
Anesthesia and Regional Anesthetic Techniques for Minimally Invasive Direct Coronary Artery Bypass Surgery
Authors: Ganapathy Sugantha , Dobkowski Wojciech , Murkin John M. , Boyd Walter D.
Published: July 2008

An innovative new approach to coronary revasculariza tion, minimally invasive direct coronary artery bypass is performed via a small anterior minithoracotomy or ministernotomy on a beating heart without the aid of cardiopulmonary bypass. Components of this tech nique, including thoracoscopic video-assisted harvest ing of the internal mammary artery, often with har monic scalpel and potentially even robotic assistance, necessitate prolonged one-lung ventilation. In the ab sence of cardioplegia, myocardial protection during normothermic beating heart surgery poses a challenge. Patient selection is important to avoid intraoperative and postoperative complications. Prolonged single- lung ventilation, incomplete revascularization in hybrid procedures, and limited access for rapid intervention pose challenges with patient management. Conversion to sternotomy may be required in 5% to 7% of patients, and extension of portals over several dermatomal seg ments mandate a versatile analgesic technique. Re gional anesthesia as analgesic adjuvant allows lighter levels of general anesthesia during surgery with mini mal intraoperative hemodynamic changes and a smooth transition to postoperative analgesia. Although a num ber of regional techniques may be used to achieve this goal, thoracic epidural analgesia or continuous percuta neous paravertebral block seem to offer specific advan tages of cardiac sympathectomy.
Mechanical Circulatory Support Sources of Emboli and Neurological Outcome
Authors: Quinn D.W. , Jones T.J.J. , Graham T.R.
Published: July 2008

Long-term mechanical circulatory support devices are currently used as bridges to transplantation or myocar dial recovery and represent a major step forward in the treatment of end-stage heart failure. Examples of left ventricular assist devices/systems are Thoratec Labora tories (Berkley, CA), Baxter Novacor (Oakland, CA), and Thermo Cardiosystems Inc Heartmate (Woburn, MA). The CardioWest (Tucson, AZ) is the current total artifi cial heart device under clinical evaluation. These de vices are associated with neurological complications usually resulting from thromboembolic events to the cerebrum, cerebellum, or brainstem. The device itself is the commonest source of these emboli. Thrombus formation within the device occurs as a result of the interaction between the blood contacting surfaces of the device, the flow of blood through the device, and thrombotic tendency of the blood. There is a wide range of clinical presentation, from asymptomatic emboli detected by transcranial Doppler to devastating strokes. Strategies aimed to reduce the tendency to form throm bus are based on aggressive prevention with anticoagu lation and antiplatelet therapy and/or by design modifi cation. In particular, the use of a textured inner surface that encourages the formation of a pseudoneointima seems successful in reducing anticoagulation require ments and neurological complications.
Observation of interdot energy transfer between InAs quantum dots
Authors: Nishibayashi K. , Kawazoe T. , Ohtsu M. , Akahane K. , Yamamoto N.
Published: July 2008

We observed interdot excitation energy transfer between vertically aligned InAs quantum dots (QDs) separated by a 24-nm-thick spacer layer. This transfer was explained by resonant energy transfer via an optical near-field interaction between the first excited state of small QDs and the second excited states of large QDs. The excitation intensity dependence of the photoluminescence intensities showed that the energy transfer times were 75ps at 15K and 4ns at 77K. Our experimental results indicated that the III-V compound semiconductor QDs are appropriate for nanophotonic switching devices.
Dielectric and polarization experiments in high loss dielectrics: A word of caution
Authors: Maglione M. , Subramanian M. A.
Published: July 2008

The recent quest for improved functional materials like high permittivity dielectrics and/or multiferroics has triggered an intense wave of research. Many materials have been checked for their dielectric permittivity or their polarization state. In this report, we call for caution when samples are simultaneously displaying an insulating behavior and a defect-related conductivity. Many oxides containing mixed valent cations or oxygen vacancies fall into this category. In such cases, most of the standard experiments may result in an effective high dielectric permittivity, which may not be related to ferroelectric polarization. Here we list a few examples of possible discrepancies between measured parameters and their expected microscopic origin.
High-mobility spin-cast organic thin film transistors
Authors: Park Sung Kyu , Mourey Devin A. , Subramanian Sankar , Anthony John E. , Jackson Thomas N.
Published: July 2008

We report high-mobility organic thin film transistors (OTFTs) with good uniformity using the small molecule organic semiconductor 2,8-difluoro-5,11-bis(triethylsilylethynyl) anthradithiophene (diF-TESADT). diF-TESADT was spin cast to form OTFTs with a carrier mobility of more than 1.5cm2∕Vs and shows a useful differential microstructure on or near pentaflorobenzenethiol (PFBT) treated Au source/drain electrodes compared to untreated Au or gate dielectric areas with improved molecular order observed on PFBT treated Au electrodes. For short channel length devices diF-TESADT crystal grains extend between the source and drain electrodes, resulting in increasing OTFT field effect mobility for decreasing gate length.
Finite element modeling of dynamics of martensitic phase transitions
Authors: Idesman Alexander V. , Cho Joon-Yeoun , Levitas Valery I.
Published: July 2008

A finite element approach is suggested for the modeling of the dynamics of multivariant martensitic phase transitions (PTs) in elastic materials at the nanoscale in the three dimensional (3D) case. The model consists of a coupled system of the Ginzburg–Landau equations for transformation strain-related order parameters and dynamic elasticity equations. Thermodynamic potential [V. Levitas and D. Preston, Phys. Rev. B 66, 134206 (2002)] that captures the main features of macroscopic stress-strain curves is used. The evolution of multivariant microstructure in a 3D specimen for cubic to tetragonal PT in a NiAl alloy is modeled with dynamic and static formulations. The numerical results show the significant influence of inertial forces on microstructure evolution.
Surface charge in dielectric barrier discharge plasma actuators
Authors: Opaits D. F. , Shneider M. N. , Miles Richard B. , Likhanskii A. V. , Macheret S. O.
Published: July 2008

Direct measurements of the dielectric surface potential and its dynamics in asymmetric dielectric barrier discharge (DBD) plasma actuators show that the charge builds up at the dielectric surface and extends far downstream of the plasma. The surface charge persists for a long time (tens of minutes) after the driving voltage has been turned off. For a sinusoidal voltage waveform, the dielectric surface charges positively. With the voltage waveform consisting of nanosecond pulses superimposed on a dc bias, the sign of the dielectric surface charge is the same as the sign (polarity) of the bias voltage. The surface charging significantly affects DBD plasma actuator performance.
Current-injected 1.54μm light emitting diodes based on erbium-doped GaN
Authors: Dahal R. , Ugolini C. , Lin J. Y. , Jiang H. X. , Zavada J. M.
Published: July 2008

Current-injected 1.54μm emitters have been fabricated by heterogeneously integrating metal organic chemical vapor deposition grown Er-doped GaN epilayers and 365nm nitride light emitting diodes. It was found that the 1.54μm emission intensity increases almost linearly with input forward current. The results represent a step toward demonstrating the feasibility for achieving electrically pumped optical amplifiers for optical communication that possess advantages of both semiconductor optical amplifiers and Er-doped fiber amplifiers.
Effects of frequency chirp on magnetron injection locking
Authors: Pengvanich P. , Lau Y. Y. , Luginsland J. W. , Gilgenbach R. M. , Cruz E. , Schamiloglu E.
Published: July 2008

The injection locking of a magnetron is theoretically analyzed when either the free running oscillator or the drive signal has a frequency chirp. It is found that complete phase locking of the signal cannot be achieved in either case. However, as long as the locking condition of Adler is well-satisfied instantaneously, a high degree of locking occurs during a major duration of the frequency chirps. The expected output phase variation is computed in terms of the noise in the free-running magnetron oscillator for the case of constant drive frequency.
Chromium and tantalum site substitution patterns in Ni3Al(L12) γ′-precipitates
Authors: Booth-Morrison Christopher , Mao Zugang , Noebe Ronald D. , Seidman David N.
Published: July 2008

The site substitution behavior of Cr and Ta in the Ni3Al(L12)-type γ′-precipitates of a Ni–Al–Cr–Ta alloy is investigated by atom-probe tomography (APT) and first-principles calculations. Measurements of the γ′-phase composition by APT suggest that Al, Cr, and Ta share the Al sublattice sites of the γ′-precipitates. The calculated substitutional energies of the solute atoms at the Ni and Al sublattice sites indicate that Ta has a strong preference for the Al sites, while Cr has a weak Al site preference. Furthermore, Ta is shown to replace Cr at the Al sublattice sites of the γ′-precipitates, altering the elemental phase partitioning behavior of the Ni–Al–Cr–Ta alloy.
Convergence of the Navier–Stokes–Poisson system to the incompressible Navier–Stokes equations
Authors: Ju Qiangchang , Li Fucai , Wang Shu
Published: July 2008

The quasineutral limit of the Navier–Stokes–Poisson system in the whole space Rd(d≥1) and in the torus Td is studied in this paper. It is shown that, for the well-prepared initial data, the global weak solution of the Navier–Stokes–Poisson system converges strongly to the strong solution of the incompressible Navier–Stokes equations.
Rotational dynamics of nitrous acid (HONO) in Kr matrix
Authors: Botan Virgiliu , Hamm Peter
Published: July 2008

With the help of ultrafast time-resolved infrared spectroscopy, we investigate rotational diffusion of cis- and trans-nitrous acid (HONO) in solid Kr at 30 K, as well as its reorientation upon the IR-driven cis→trans isomerization. We find different mobilities for the two isomers: cis-HONO is pinned to the matrix with no decay of the anisotropy on the 100 ns time scale, whereas trans-HONO rotates around its long axis, reducing its anisotropy partially on that time scale. The long axis itself, defined by the terminal oxygen and hydrogen atoms of HONO, stays fixed on even a minute time scale. Accompanying molecular dynamics simulations reproduce the anisotropic rotational diffusion of trans-HONO correctly, although on a completely wrong time scale, whereas they would predict complete reorientation of cis-HONO within ≈10 ps, in harsh disagreement with the experiment. We attribute the mismatch of orientational time scales to either too soft interaction potentials or to the fact that HONO occupies an interstitial rather than a monosubstitutional matrix site. The experiments furthermore show that the direction of the OH bond hardly changes during the IR-driven cis→trans isomerization, in contrast to the intuitive picture that it is mostly the light hydrogen which moves. Rather, it is the two central nitrogen and oxygen atoms that are removed during isomerization in a hula hoop fashion, whereas the terminal atoms are still pinned to the matrix cage.
Device study, chemical doping, and logic circuits based on transferred aligned single-walled carbon nanotubes
Authors: Wang Chuan , Ryu Koungmin , Badmaev Alexander , Patil Nishant , Lin Albert , Mitra Subhasish , Wong H.-S. Philip , Zhou Chongwu
Published: July 2008

In this paper, high-performance back-gated carbon nanotube field-effect transistors based on transferred aligned carbon nanotubes were fabricated and studies found that the on/off ratio can reach 107 and the current density can reach 1.6μA∕μm after electrical breakdown. In addition, chemical doping with hydrazine was used to convert the p-type aligned nanotube devices into n-type. These devices were further utilized to demonstrate various logic circuits, including p-type metal-oxide-semiconductor inverters, diode-loaded inverters, complementary metal-oxide-semiconductor inverters, NAND, and NOR gates. This approach could work as the platform for future nanotube-based nanoelectronics.
Laser induced effects on ZnO targets upon ablation at 266 and 308nm wavelengths
Authors: Jadraque María , Domingo Concepción , Martín Margarita
Published: July 2008

The development of structural changes in ZnO targets, upon laser irradiation at the wavelengths of 266 and 308nm, is studied by Raman spectroscopy. At the wavelength of 308nm, oxygen vacancies are found to develop monotonically with increasing laser intensity. At 266nm, a structural change in the irradiated ZnO targets, possibly related to nanostructuring, is observed above the laser fluence of 0.45Jcm−2. The different natures of the laser target interaction processes taking place at both wavelengths are investigated through the characterization of the composition and energy distribution of the species ejected in the ablation. The energy of the neutral Zn and Zn2 present in the ablation at 308nm shows a smooth dependence on laser fluence which is consistent with the observed smooth development of oxygen vacancies. At 266nm, the average kinetic energy of the ejected fragments is higher than at 308nm and changes abruptly with the ablating laser fluence, consistently with the presence of a fluence threshold above which structural transform is observed at this wavelength. The plume shows the same neutral composition (Zn, ZnO, and Zn2) at both wavelengths but the dependence on fluence of the ratio of neutral atomic Zn to the dimer Zn2 shows significant differences. From the latter, different temperature regimes can be inferred in the plume generated at both wavelengths. At 266nm the cationic composition of the plume is mainly stoichiometric whereas at 308nm ZnO2(3)H2(1)+ cations have the highest intensity.
Structural conditions that leads to photoluminescence emission in SrTiO3: An experimental and theoretical approach
Authors: Longo V. M. , de Figueiredo A. T. , de Lázaro S. , Gurgel M. F. , Costa M. G. S. , Paiva-Santos C. O. , Varela J. A. , Longo E. , Mastelaro V. R. , DE Vicente F. S. , Hernandes A. C. , Franco R. W. A.
Published: July 2008

Complex cluster [TiO5⋅VOz] and [SrO11⋅VOz] (where VOz=VOX, VO•, VO••) vacancies were identified in disordered SrTiO3 powders prepared by the polymeric precursor method, based on experimental measurements by x-ray absorption near edge structure spectroscopy. The paramagnetic complex states of [TiO5⋅VO•] and [SrO11⋅VO•] with unpaired electrons were confirmed by electron paramagnetic resonance spectroscopy. The disordered powders showed strong photoluminescence at room temperature. Structural defects of disordered powders, in terms of band diagram, density of states, and electronic charges, were interpreted using high-level quantum mechanical calculations in the density functional framework. The four periodic models used here were consistent with the experimental data and explained the presence of photoluminescence.
Decay of passive scalar fluctuations in homogeneous magnetohydrodynamic turbulence
Authors: Kinet Maxime , Burattini Paolo , Carati Daniele , Knaepen Bernard
Published: July 2008

We study the decay of passive scalar fluctuations in homogeneous magnetohydrodynamic turbulence, by performing direct numerical simulations in a cubic box. The applied magnetic field is constant and uniform, while the magnetic Reynolds number is much less than 1, hence the quasistatic approximation is used. The effect of the magnetic field on the decay rate of the scalar variance is documented, also in comparison to the hydrodynamic (i.e., nonmagnetic) case. At large times, the scalar variance decays according to an exponential law. Furthermore, the results show that the scalar, which is initially isotropic, develops rapidly an anisotropic state. Its intensity depends on the anisotropy of the flow and on the Schmidt number. The anisotropy of the velocity field is reflected on that of the scalar, as Fourier modes corresponding to wavevectors having a large component parallel to the magnetic field are more attenuated. Anisotropy at large and small scales is analyzed by computing several statistical quantities in physical and spectral spaces. It is found that the scalar is mainly anisotropic at large wavenumbers; an explanation based on the scalar transfer properties is provided.
Two point third order correlation functions for quasigeostrophic turbulence: Kolmogorov–Landau approach
Authors: Chakraborty Sagar
Published: July 2008

We use the more intuitive approach due to Kolmogorov (and, subsequently, Landau in his text on fluid dynamics) to calculate some third order structure functions for quasigeostrophic turbulence for the forward cascade of pseudopotential enstrophy and the inverse energy cascade in quasigeostrophic turbulence.