bluuebunny/crossref_metadata_2025 huggingface dataset:
An Overview of Challenges in Modeling Heat and Mass Transfer for Living on Mars
Authors: YAMASHITA MASAMICHI , ISHIKAWA YOJI , KITAYA YOSHIAKI , GOTO EIJI , ARAI MAYUMI , HASHIMOTO HIROFUMI , TOMITA‐YOKOTANI KAORI , HIRAFUJI MASAYUKI , OMORI KATSUNORI , SHIRAISHI ATSUSHI , TANI AKIRA , TOKI KYOICHIRO , YOKOTA HIROKI , FUJITA OSAMU
Published: November 2006

Abstract:  Engineering a life‐support system for living on Mars requires the modeling of heat and mass transfer. This report describes the analysis of heat and mass transfer phenomena in a greenhouse dome, which is being designed as a pressurized life‐support system for agricultural production on Mars. In this Martian greenhouse, solar energy will be converted into chemical energy in plant biomass. Agricultural products will be harvested for food and plant cultivation, and waste materials will be processed in a composting microbial ecosystem. Transpired water from plants will be condensed and recycled. In our thermal design and analysis for the Martian greenhouse, we addressed the question of whether temperature and pressure would be maintained in the appropriate range for humans as well as plants. Energy flow and material circulation should be controlled to provide an artificial ecological system on Mars. In our analysis, we assumed that the greenhouse would be maintained at a subatmospheric pressure under 1/3‐G gravitational force with 1/2 solar light intensity on Earth. Convection of atmospheric gases will be induced inside the greenhouse, primarily by heating from sunlight. Microclimate (thermal and gas species structure) could be generated locally around plant bodies, which would affect gas transport. Potential effects of those environmental factors are discussed on the phenomena including plant growth and plant physiology and focusing on transport processes. Fire safety is a crucial issue and we evaluate its impact on the total gas pressure in the greenhouse dome.
Structure of High‐Performance Evaporators for Space Application
Authors: OHTA HARUHIKO , SHINMOTO YASUHISA , MIZUKOSHI TOSHIYUKI , ISHIKAWA YOSUKE
Published: November 2006

Abstract:  A new structure of cold plates, where an unheated auxiliary channel is installed to supply liquid directly to the bottom of coalesced flattened bubbles in a narrow heated channel, is tested to investigate the increase in critical heat flux. Assuming the application to the laser solar power system, a large heating surface with a length of 150 mm in the flow direction is employed, and a narrow channel structure is adopted to reduce the size of cold plates, where the gap sizes are selected as 5 mm and 2 mm. Experiments are performed for water as a test liquid at inlet subcooling of 15 K under near atmospheric pressure. Inlet liquid velocity is varied from 0.065 m/s to 0.6m/s for the upward flow on ground. A value of critical heat flux of 2.2 × 106 W/m2 is obtained for 5‐mm gap size at the inlet velocity of 0.2 m/s. At low liquid flow rate, the structure realizes the CHF values larger by 2.5 times than those for the normal heated channel without additional liquid supply. A new method to evaluate the performance of cold plates is proposed to take account of the variation in the size of heating surface, inlet liquid velocity, and subcooling that influence the CHF values. The validity of the proposed structure of the cold plate for the increase in critical heat flux is confirmed.
A Microgravity Experiment of the On‐Orbit Fluid Transfer Technique Using Swirl Flow
Authors: KAWANAMI OSAMU , IMAI RYOJI , AZUMA HISAO , OHTA HARUHIKO , HONDA ITSURO , KAWASHIMA YOUSUKE
Published: November 2006

Abstract:  The cryogenic fluid transfer technique will prove useful for flexible and low‐cost space activities by prolonging the life cycle of satellites, orbital transfer vehicles, and orbital telescopes that employ cryogenic fluids, such as reactants, coolants, and propellants. Although NASA has conducted extensive research on this technique to date, a complicated mechanism is required to control the pressure in the receiver tank and avoid a large liquid loss by vaporization. We have proposed a novel fluid transfer method by using swirl flow combined with vapor condensation facilitated by spray cooling. This technique enables gas–liquid separation in microgravity and effectively facilitates vapor condensation without any special device like a mixer. In addition, since the incoming liquid flows along the tank wall, the tank wall would be cooled effectively, thereby minimizing the liquid loss due to vaporization. In this paper, the influence of the number of inlet points, fluid velocity at the inlet, fluid type, and boiling condition on swirl flow under microgravity conditions is investigated experimentally. The results indicated that the new fluid transfer technique using the swirl flow proposed by us is effective for cryogenic fluids that generally exhibit low surface tension and good wettability. In addition, it is possible to apply this technique to the real system because the swirl flow conditions are determined by the Froude number, which is dimensionless. Thus, the fundamental technique of fluid transfer by using the swirl flow under microgravity conditions was established.
Axisymmetric Surface Oscillations in a Cylindrical Container with Compensated Gravity
Authors: GERSTMANN JENS , DREYER MICHAEL E.
Published: November 2006

Abstract:  In this study the first mode of axisymmetric surface oscillations of a free liquid interface in a partly filled right circular cylinder under compensated gravity is investigated numerically. The situation is similar to a spacecraft that enters a ballistic flight at the end of thrust. A reorientation of the liquid of the free liquid surface toward the new equilibrium position takes place. The characteristics of this flow, such as the frequency and the damping, are governed by the behavior of the contact line. The investigations focus on the dependence on the contact line boundary condition, including contact angle variation, and on viscous effects. The effect on the natural frequency and the damping is considered. An analytical approximation for the frequency behavior for a frictionless liquid for a free and a fixed contact line condition is given. Further analytical approximations for the damping behavior in dependence on the contact angle and the Ohnesorge number are determined. The numerical results show very good agreement with experimental data.
Heat and Gas Exchanges between Plants and Atmosphere under Microgravity Conditions
Authors: KITAYA YOSHIAKI , KAWAI MASAYUKI , TAKAHASHI HIDEYUKI , TANI AKIRA , GOTO EIJI , SAITO TAKAHIRO , SHIBUYA TOSHIO , KIYOTA MAKOTO
Published: November 2006

Abstract:  Fundamental studies were conducted to develop a facility having an adequate air circulation system for growing healthy plants over a long term under microgravity conditions in space. To clarify the effects of gravity on heat and gas exchanges between plant leaves and the ambient air, surface temperatures and net photosynthetic rates of barley leaves were evaluated at gravity levels of 0.01, 1.0, and 2.0 g for 20 sec each during parabolic airplane flights. Thermal images were captured using infrared thermography at an air temperature of 22°C, a relative humidity of 18%, and an irradiance of 260 W/m2. The net photosynthetic rates were determined by means of a chamber method with an infrared gas analyzer at an air temperature of 20°C, a relative humidity of 50%, and photosynthetic photon fluxes (PPFDs) of 250 and 500 μmol/m2/sec. Mean leaf temperatures increased by 1.9°C with decreasing gravity levels from 1.0 to 0.01 g and decreased by 0.6°C with increasing gravity levels from 1.0 to 2.0 g. The increase in leaf temperatures was greater at the regions closer to the leaf tip and at most 2.5°C over 20 sec as gravity decreased from 1.0 to 0.01 g. The net photosynthetic rate decreased by 20% with decreasing gravity levels from 1.0 to 0.01 g and increased by 10% with increasing gravity levels from 1.0 to 2.0 g at a PPFD of 500 μmol/m2/sec. The heat and gas exchanges between leaves and the ambient air were suppressed more at the lower gravity levels. The retardation would be caused by heat and gas transfers with less heat convection. Restricted free air convection under microgravity conditions in space would limit plant growth by retarding heat and gas exchanges between leaves and the ambient air.
Gas Embolism and Surfactant‐Based Intervention
Authors: ECKMANN DAVID M. , ZHANG JIE , LAMPE JOSHUA , AYYASWAMY PORTONOVO S.
Published: November 2006

Abstract:  Intravascular gas embolism can occur with decompression in space flight, and it commonly occurs during cardiac and vascular surgery. Intravascular bubbles may be deposited into any end organ such as the heart or the brain. Surface interactions between the bubble and the endothelial cells lining the vasculature result in serious impairment of blood flow and can lead to heart attack, stroke, or even death. Surfactant‐based intervention is a novel treatment for gas embolism. Intravascular surfactant can adsorb onto the gas–liquid interface and compete with blood‐borne macromolecules for interfacial occupancy. Surfactants can retard the progress of pathophysiological molecular and cellular events stimulated by the bubble surface, including endothelial cell injury and initiation of blood clotting. Bulk and surface transport of a surfactant to provide competition for interfacial occupancy is a therapeutic strategy because surfactant adsorption can dominate protein (or other macromolecule) adsorption. The presence of surfactant along the gas–liquid interface also induces variation in the interfacial tension, which in turn affects the blood flow and the bubble motion. We describe the interplay between biological transport processes and physiological events occurring and the cellular and molecular level in vascular gas embolization. Special consideration is given to modeling the transport and hydrodynamic interactions associated with surfactant‐based intervention.
Analysis of Heat and Mass Transfer during Condensation over a Porous Substrate
Authors: BALASUBRAMANIAM R. , NAYAGAM V. , HASAN M.M. , KHAN L.
Published: November 2006

Abstract:  Condensing heat exchangers are important in many space applications for thermal and humidity control systems. The International Space Station uses a cooled fin surface to condense moisture from humid air that is blown over it. The condensate and the air are “slurped” into a system that separates air and water by centrifugal forces. The use of a cooled porous substrate is an attractive alternative to the fin where condensation and liquid/gas separation can be achieved in a single step. We analyze the heat and mass transfer during condensation of moisture from flowing air over such a cooled, flat, porous substrate. A fully developed regime is investigated for coupled mass, momentum and energy transport in the gas phase, and momentum and energy transport in the condensate layer on the porous substrate and through the porous medium.
Containerless Measurements of Thermophysical Properties of Zr54Ti8Cu20Al10Ni8
Authors: BRADSHAW R.C. , WARREN M.E. , ROGERS J.R. , RATHZ T.J. , GANGOPADHYAY A.K. , KELTON K.F. , HYERS R.W.
Published: November 2006

Abstract:  High‐temperature measurement and study of reactive materials can be difficult with conventional processing methods because contamination from the measuring apparatus and container walls can adversely affect measurements. Containerless processing techniques can be employed to isolate samples from their environment, reducing contamination. Benefits of containerless processing include reduction in heterogeneous nucleation sites, which in turn delays the onset of solidification and allows the study of meta‐stable undercooled phases. However, property measurements must use noncontact methods as well. Fortunately, several optical‐based methods have been developed and successfully employed to measure thermophysical properties, including surface tension, viscosity, density, and thermal expansion. Combining these techniques with the electrostatic levitator (ESL) located at the NASA Marshall Space Flight Center (MSFC) has resulted in an excellent facility to perform containerless material studies which support microgravity flight projects. Currently, studies of the thermophysical properties of liquid quasi‐crystal forming and related alloys ranging from superheated to deeply undercooled states are being done with this facility in support of the NASA‐funded flight project Quasi‐crystalline Undercooled Alloys for Space Investigation (QUASI). While the primary purpose of these measurements is to support planned flight experiments, they are also a desirable resource for future manufacturing considerations and for fundamental insight in the physics of icosahedral ordering in liquids and solids. Presented here is an overview of the contactless measuring methods for surface tension, viscosity, density, and thermal expansion applied to Zr54Ti8Cu20Al10Ni8, for the superheated and meta‐stable undercooled liquid phases, in support of QUASI.
Effect of Convection on the Measurement of Thermophysical Properties Using Levitated Droplets
Authors: LI B.Q.
Published: November 2006

Abstract:  This article discusses the recirculating convection in free droplets levitated by either the electromagnetic forces or the electrostatic forces, and its effect on the measurement of thermophysical properties. In an electromagnetically levitated droplet, strong internal flow results from the vortical Lorentz forces induced by the surrounding coils. These forces are also responsible for free surface deformation. In an electrostatically levitated droplet, however, internal convection originates from the thermal gradient and the electrostatic forces are responsible for surface deformation only. Mathematical models for predicting the convection in these droplets and the surface deformations caused by either the electromagnetic or electrostatic forces are discussed. Results show that internal convection, when present, can have a significant effect on the measured data for the purpose of determining the thermophysical properties. The deformed surface assumes essentially the same oval shape in microgravity for both electromagnetically and electrostatically levitated drops. The deformation mechanism, however, is different. Future research directions in this area are also discussed.
Developing Quantitative, Multiscale Models for Microgravity Crystal Growth
Authors: DERBY JEFFREY J. , KWON YONG‐Il , PANDY ARUN , SONDA PAUL , YECKEL ANDREW , JUNG THOMAS , GEORG MÜLLER AND
Published: November 2006

Abstract: Crystal growth conducted under microgravity conditions has had a profound impact on improving our understanding of melt crystal growth processes. Here, we present a brief history of microgravity crystal growth and discuss the development of appropriate models to interpret and optimize these growth experiments. The need for increased model realism and predictive capability demands new approaches for describing phenomena important at several disparate length scales. Of special importance is the ability to represent three‐dimensional and transient continuum transport (flows, heat, and mass transfer), phase‐change phenomena (thermodynamics and kinetics), and system design (such as furnace heat transfer during melt growth). An overview of mathematical models and numerical algorithms employed to represent such multiscale effects is presented.
Causal Relationship between Non‐Hodgkin's Lymphoma and Exposure to Benzene and Benzene‐Containing Solvents
Authors: MEHLMAN MYRON A.
Published: November 2006

Abstract:  Non‐Hodgkin's lymphoma (NHL) is a malignant neoplasm of the lymphatic system made up of mainly B cell lymphocytes. A large number of studies have shown significant associations between NHL and benzene or benzene‐containing solvents and products. This article summarizes studies detailing these associations and indicates those that are significant. Based on an analysis of the literature and the weight of evidence from numerous studies, it is reasonable to conclude that exposure to benzene or to solvents or products containing benzene is causally related to NHL.
Causal Relationship from Exposure to Chemicals in Oil Refining and Chemical Industries and Malignant Melanoma
Authors: MEHLMAN MYRON A.
Published: November 2006

Abstract:  Malignant melanoma has been thought to be related mainly to exposure to the sun or radiation. A review of the scientific literature reveals many significant correlations between benzene and benzene‐containing solvents in the workplace and the occurrence of malignant melanoma, particularly in sites that have never been exposed to sunlight. A comparison of positive correlations between such exposure and malignant melanoma by independent investigators and negative findings by investigators with industry affiliations reveals that this difference, at least in part, may account for the discrepant findings. Based on independent studies, it is reasonable to conclude that malignant melanoma is causally related to employment‐related chemical exposures in the petroleum refining industry.
Hazardous Anticancer Drugs in Health Care
Authors: CONNOR THOMAS H.
Published: November 2006

Abstract:  Exposure of healthcare workers to anticancer drugs became problematic in the 1970s. Shortly thereafter, studies began documenting exposure of healthcare workers to these drugs. Investigations employing biological markers, such as urine mutagenicity, chromosomal aberrations, sister chromatid exchanges, and micronuclei, demonstrated associations between occupational exposures and elevated marker levels. Other analytical methods emerged to monitor workplaces where drugs were handled. These contemporary studies uncovered widespread contamination of drugs on work surfaces, trace amounts in air samples, and their presence in the urine of workers. Vials containing these drugs are often contaminated with the drug when they are shipped. Most workplace surfaces are contaminated with the drugs being prepared and used in that area. Other anticancer/hazardous drugs would most likely be used in these areas. The interior surfaces of biological safety cabinets and isolators, floors, countertops, carts, storage bins, waste containers, treatment areas, tabletops, chairs, linen, and other items are all potential sources of exposure to anticancer drugs. Patient body fluids contain the drugs and/or metabolites, often more biologically active than the parent compounds. An exposure assessment of areas where anticancer/hazardous drugs are handled must consider every potential source and route of exposure. Data from surface contamination and inhalation studies suggest that dermal exposure is the primary route of exposure. Assessment of exposure is the first step in providing a safe work environment for these workers. However, because of the many drugs to which they are exposed, any assessment can only be an estimation of the overall exposure.
A Regional Approach to Assess the Impact of Living in a Chemical World
Authors: DE ROSA CHRISTOPHER T. , HICKS HERALINE E. , ASHIZAWA ANNETTE E. , POHL HANA R. , MUMTAZ M. MOIZ
Published: November 2006

Abstract:  In the United States, some 80,000 commercial and industrial chemicals are now in use of which over 30,000 are produced or used in the Great Lakes region. Thus, the environmental quality within the Great Lakes basin has been compromised particularly with respect to persistent toxic substances (PTS). Information derived from wildlife studies, prospective epidemiological and toxicological studies, databases, demographics, and Geographical Information Systems (GIS) demonstrate significant public health implications. Studies of human populations indicate: (a) elevated body burden levels of PTSs, (b) decrease in gestational age, (c) low birth weight (LBW), (d) greater risk of male children with birth defects (OR = 3.01), (e) developmental and neurological deficits, (f) increased risk of infertility, (g) changes in sex ratio, and (h) fluctuations in thyroid hormones. These findings have been identified in vulnerable populations, such as the developing fetus, children, minorities, and men and women of reproductive age who are more susceptible because of their physiologic sensitivity and/or elevated exposure to toxic chemicals.
Typically such health effects are assessed on a chemical specific basis; however, most human populations are exposed to hazardous chemicals as mixtures in air, water, soil, and biota. In this article we present an assessment of the potential for joint toxic action of these substances in combinations in which they are typically found. These evaluations represent an integration of all available scientific evidence in accordance with the “NAS paradigm” for risk assessment. In aggregate, our evaluations have demonstrated a need for community‐based frameworks and computational techniques to track patterns of environmentally related exposures and associated health effects.
Environmental Impacts on Children's Health in Southeast Asia
Authors: RUCHIRAWAT MATHUROS , NAVASUMRIT PANIDA , SETTACHAN DAAM , AUTRUP HERMAN
Published: November 2006

Abstract:  Air pollution is a serious problem in many countries in Southeast Asia, particularly in major metropolises with high levels of traffic congestion generating significant amounts of genotoxic substances. The contribution of such environmental exposure to children's illnesses, such as respiratory diseases and cancer, is a public health concern. Inner‐city children may have higher levels of exposure to genotoxic substances in the air than those living in rural areas. This study was conducted in Bangkok, where ambient levels of polycyclic aromatic hydrocarbons (PAHs) and benzene are relatively high. Bangkok school children were exposed to total PAHs at about sixfold higher levels than those in rural areas, with levels of urinary 1‐hydroxypyrene (1‐OHP) also being significantly higher. PAH–DNA adduct levels in lymphocytes were fivefold higher in Bangkok children. Benzene exposure in Bangkok school children was more than twofold higher than the levels measured in children from the rural areas. This is in agreement with the biomarkers of internal dose, that is, blood benzene and urinary trans, trans‐muconic acid (t,t‐MA) levels. The potential health risks from exposure to PAHs and benzene were assessed through the use of DNA damage and DNA repair capacity as markers of early biological effect. DNA strand breaks were significantly higher in Bangkok school children, while DNA repair capacity was significantly lower. It appears that children in major cities in developing countries may have an increased health risk for the development of certain diseases, such as cancer due to exposure to genotoxic substances in their environment.
The Economic Costs of Health Service Treatments for Asbestos‐Related Mesothelioma Deaths
Authors: WATTERSON ANDREW , GORMAN TOMMY , MALCOLM CARI , ROBINSON MAVIS , BECK MATTHIAS
Published: November 2006

Abstract:  This article explores the complex and neglected picture of occupational and environmental disease healthcare costs specifically relating to asbestos. Diagnosed mesothelioma cases in Scotland in one calendar year were used to investigate the subject in greater depth. Data from UK sources on asbestos disease types recorded in 2000 and their disease treatment costs were obtained. Acute care economic costs of these diseases are estimated. One hundred and twenty diagnosed, recorded, and treated cases of asbestos‐related diseases occurred in 2000 in Scotland. Mesothelioma accounted for 100 cases and directly cost Scottish National Health Service hospitals an estimated £942,038. The estimated UK figure in 2000 was at least £16,014,646 because official figures for diagnosed and recorded deaths from mesothelioma are running at over 1700 a year with rises predicted for 2010 of 2000 deaths. By 2003, 50,000 people in the UK had died from diagnosed and recorded mesothelioma since records began. Earlier disease treatment costs would have been significantly lower than those in 2000 but, at 2000 prices, cost to the UK was roughly £471,019,000 in acute hospital expenditure. Figures for primary care costs, including caregiver costs, are incomplete or unknown. These disease costs are substantial and have some international generalizability. Treatment patterns and costs vary greatly. Many lung cancer cases due to asbestos exposure occur globally for each mesothelioma case. Hence figures provided in this article are certain to be gross underestimates of the total health service and personal economic costs of asbestos illness and treatment in Scotland.
Potential Health Effects of Occupational Chlorinated Solvent Exposure
Authors: RUDER AVIMA M.
Published: November 2006

Abstract: Based on toxicology, metabolism, animal studies, and human studies, occupational exposure to chlorinated aliphatic solvents (methanes, ethanes, and ethenes) has been associated with numerous adverse health effects, including central nervous system, reproductive, liver, and kidney toxicity, and carcinogenicity. However, many of these solvents remain in active, large‐volume use. This article reviews the recent occupational epidemiology literature on the most widely used solvents, methylene chloride, chloroform, trichloroethylene, and tetrachloroethylene, and discusses other chlorinated aliphatics. The impact of studies to date has been lessened because of small study size, inability to control for confounding factors, particularly smoking and mixed occupational exposures, and the lack of evidence for a solid pathway from occupational exposure to biological evidence of exposure, to precursors of health effects, and to health effects. International differences in exposure limits may provide a “natural experiment” in the coming years if countries that have lowered exposure limits subsequently experience decreased adverse health effects among exposed workers. Such decreases could provide some evidence that higher levels of adverse health effects were associated with higher levels of solvent exposure. The definitive studies, which should be prospective biomarker studies incorporating body burden of solvents as well as markers of effect, remain to be done.
Manufactured Uncertainty
Authors: MICHAELS DAVID
Published: November 2006

Abstract:  The strategy of “manufacturing uncertainty” has been used with great success by polluters and manufacturers of dangerous products to oppose public health and environmental regulation. This strategy entails questioning the validity of scientific evidence on which the regulation is based. While this approach is most identified with the tobacco industry, it has been used by producers of asbestos, benzene, beryllium, chromium, diesel exhaust, lead, plastics, and other hazardous products to avoid environmental and occupational health regulation. It is also central to the debate on global warming. The approach is now so common that it is unusual for the science not to be challenged by an industry facing regulation. Manufacturing uncertainty has become a business in itself; numerous technical consulting firms provide a service often called “product defense” or “litigation support.” As these names imply, the usual objective of these activities is not to generate knowledge to protect public health but to protect a corporation whose products are alleged to have toxic properties. Evidence in the scientific literature of the funding effect—the close correlation between the results of a study desired by a study's funder and the reported results of that study—suggests that the financial interest of a study's sponsors should be taken into account when considering the study's findings. Similarly, the interpretation of data by scientists with financial conflicts should be seen in this light. Manufacturing uncertainty is antithetical to the public health principle that decisions be made using the best evidence currently available.
Developments in Management and Technology of Waste Reduction and Disposal
Authors: RUSHBROOK PHILIP
Published: November 2006

Abstract:  Scandals and public dangers from the mismanagement and poor disposal of hazardous wastes during the 1960s and 1970s awakened the modern‐day environmental movement. Influential publications such as “Silent Spring”

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and high‐profile disposal failures, for example, Love Canal and Lekkerkerk, focused attention on the use of chemicals in everyday life and the potential dangers from inappropriate disposal. This attention has not abated and developments, invariably increasing expectations and tightening requirements, continue to be implemented. Waste, as a surrogate for environmental improvement, is a topic where elected representatives and administrations continually want to do more. This article will chart the recent changes in hazardous waste management emanating from the European Union legislation, now being implemented in Member States across the continent. These developments widen the range of discarded materials regarded as “hazardous,” prohibit the use of specific chemicals, prohibit the use of waste management options, shift the emphasis from risk‐based treatment and disposal to inclusive lists, and incorporate waste producers into more stringent regulatory regimes. The impact of the changes is also intended to provide renewed impetus for waste reduction. Under an environmental control system where only certainty is tolerated, the opportunities for innovation within the industry and the waste treatment and disposal sector will be explored. A challenging analysis will be offered on the impact of this regulation‐led approach to the nature and sustainability of hazardous waste treatment and disposal in the future.
Geographic Model and Biomarker‐Derived Measures of Pesticide Exposure and Parkinson's Disease
Authors: RITZ BEATE , COSTELLO SADIE
Published: November 2006

Abstract:  For more than two decades, reports have suggested that pesticides and herbicides may be an etiologic factor in idiopathic Parkinson's disease (PD). To date, no clear associations with any specific pesticide have been demonstrated from epidemiological studies perhaps, in part, because methods of reliably estimating exposures are lacking. We tested the validity of a Geographic Information Systems (GIS)‐based exposure assessment model that estimates potential environmental exposures at residences from pesticide applications to agricultural crops based on California Pesticide Use Reports (PUR). Using lipid‐adjusted dichlorodiphenyldichloroethylene (DDE) serum levels as the “gold standard” for pesticide exposure, we conducted a validation study in a sample taken from an ongoing, population‐based case–control study of PD in Central California. Residential, occupational, and other risk factor data were collected for 22 cases and 24 controls from Kern county, California. Environmental GIS–PUR‐based organochlorine (OC) estimates were derived for each subject and compared to lipid‐adjusted DDE serum levels. Relying on a linear regression model, we predicted log‐transformed lipid‐adjusted DDE serum levels. GIS–PUR‐derived OC measure, body mass index, age, gender, mixing and loading pesticides by hand, and using pesticides in the home, together explained 47% of the DDE serum level variance (adjusted r2= 0.47). The specificity of using our environmental GIS–PUR‐derived OC measures to identify those with high‐serum DDE levels was reasonably good (87%). Our environmental GIS–PUR‐based approach appears to provide a valid model for assessing residential exposures to agricultural pesticides.
Clinicopathological Conference: Case Report—A Case of Anorexia and Weak Arm
Authors: Wiler Jennifer L. , Bailey Heatherlee
Published: November 2006

The authors present the case of a 49‐year‐old female who presented to the emergency department with a chief complaint of “not eating well.” She was found to have a heart murmur, a focal neurological deficit, and large mitral valve vegetation. The patient was later diagnosed with acute Pseudomonal endocarditis with septic emboli to the brain, liver, spleen, and kidneys. A discussion of the patient presentation, diagnostic evaluation, and outcome are reviewed.
Supporting staff after serious incidents
Authors: Vincent Charles
Published: November 2006

Virtually every clinician knows the sickening feeling of making a bad mistake. You feel singled out and exposed - seized by the instinct to see if anyone has noticed. You agonize about what to do, whether to tell anyone, what to say. Later, the event replays itself in your mind. You question your competence but fear being discovered. You know you should confess, but dread the prospect of potential punishment and of the patient's anger.
Role of metal ions in the tetraloop–receptor complex as analyzed by NMR
Authors: Davis Jared H. , Foster Trenton R. , Tonelli Marco , Butcher Samuel E.
Published: November 2006

Metal ions are critical for the proper folding of RNA, and the GAAA tetraloop–receptor is necessary for the optimal folding and function of many RNAs. We have used NMR to investigate the role of metal ions in the structure of the tetraloop–receptor in solution. The NMR data indicate native tertiary structure is formed under a wide range of ionic conditions. The lack of conformational adaptation in response to very different ionic conditions argues against a structural role for divalent ions. Nuclear Overhauser effects to cobalt hexammine and paramagnetic relaxation enhancement induced by manganese ions were used to determine the NMR structures of the tetraloop receptor in association with metal ions, providing the first atomic-level view of these interactions in the solution state. Five manganese and two cobalt hexammine ions could be localized to the RNA surface. The locations of the associated metal ions are similar, but not identical to, those of previously determined crystal structures. The sites of association are in general agreement with nonlinear Poisson–Boltzmann calculations of the electrostatic surface, emphasizing the general importance of diffusely associated ions in RNA tertiary structure.
The Retention of Blance: An Exploratory Study into the Limits of Acceleration the Human Body Can Withstand without Losing Equilibrium
Authors: Graaf Bernd De , Van Weperen Willem
Published: November 2006

The human limiting values for sudden accelerations we have determined can be used to evaluate specific physical conditions that cause problems in maintaining postural balance. A comparison between the data obtained in the laboratory and the situations occurring during public transport by tram, bus, and metro revealed that both the initial impetus ("jerk") and the level of acceleration found in practice were sufficient to ensure that none of the individuals measured in the laboratory would have been able to retain their balance without extra support. The study suggests that limiting the initial jerk component of the acceleration would help considerably in alleviating the problem.
Performance during Positive Pressure Breathing after Rapid Decompression Up to 72000 Feet
Authors: Lindeis Ann Elise , Fraser W. D. , Fowler Barry
Published: November 2006

Positive pressure breathing (PPB) is a survival system that delivers high-pressure oxygen and body counterpressure in the event of cockpit depressurization at high altitude, but the ability of aircrew to perform an emergency "get-me-down" maneuver with this system is unknown. To address this question, a serial choice reaction time (RT) task was administered to six participants, who were sustained with PPB after rapid decompression to 60000 feet (18 288 m) or 72 000 feet (21946 m) in a hypobaric chamber (Experiment 1). Hypoxia was monitored by blood oxygen saturation (SaO2). Experiment 2 assessed the effects of PPB alone on performance. In Experiment 3, performance was measured while the rate of decrease of Sao2 observed in Experiment 1 was replicated with low oxygen mixtures at ground level. During the first 60 s at 72 000 feet, RT increased by 79 ms because of a shift of the whole distribution to the right. PPB at ground level did not increase RT. Decreasing Sao2 at ground level increased RT, but only after a delay. We conclude that inattention to the task, PPB alone, or, surprisingly, hypoxia cannot explain the majority of the impairment observed in Experiment 1. Rather, PPB and low pressure at high altitude interacted to exacerbate lacrimation, thereby degrading vision. Implications for the design of get-me-down maneuvers are discussed.
Policy Improvements for Prevention of Alcohol Misuse by Airline Pilots
Authors: McFadden Kathleen L.
Published: November 2006

Alcohol abuse by airline pilots poses a potential danger to the safety and welfare of the flying public. This paper analyzes two strategies for reducing pilot-error aviation accidents: conducting background checks on pilots for driving-while-intoxicated (DWI) convictions and random preflight alcohol testing of airline pilots. Although both policies have been implemented, no empirical research had previously been conducted to justify either strategy. The results and conclusions of this study are based on analysis of data obtained from the Federal Aviation Administration on the flying performance of 70 164 airline pilots. DWI convictions were found to be associated with a significantly greater risk of a pilot-error accident. In contrast, no evidence was found to validate the assumption that a random alcohol testing program could have prevented accidents. The results provide support for improving the existing DWI background check program and for reducing the sampling rate of random alcohol testing for airline pilots. This twofold strategy could result in greater improvements in aviation safety and reduced overall costs.
Vigilance and Signal Detection Theory: An Empirical Evaluation of Five Measures of Response Bias
Authors: See Judi E. , Warm Joel S. , Dember William N. , Howe Steven R.
Published: November 2006

Three experiments were conducted to determine which of five response bias indices (β, c, B", B'H and B"D) defined by the theory of signal detection provides the most effective measure of the observer's willingness to respond in a vigilance task. The results indicated that the traditional parametric bias index β was an inadequate measure of response bias in every respect, whereas the newer parametric measure c was the most effective of all five indices. When the three nonparametric measures (B", B'H' and B"D) were examined separately, B"D emerged as the most effective nonparametric index. We recommend that vigilance researchers use c rather than β to measure bias when a parametric model is involved and B"D instead of B" and B' H when a nonparametric model is used.
Chromatic Properties of Horizontal and Ganglion Cell Responses Follow a Dual Gradient in Cone Opsin Expression
Authors: Yin Lu , Smith Robert G , Sterling Peter , Brainard David H.
Published: November 2006

In guinea pig retina, immunostaining reveals a dual gradient of opsins: cones expressing opsin sensitive to medium wavelengths (M) predominate in the upper retina, whereas cones expressing opsin sensitive to shorter wavelengths (S) predominate in the lower retina. Whether these gradients correspond to functional gradients in postreceptoral neurons is essentially unknown. Using monochromatic flashes, we measured the relative weights with which M, S, and rod signals contribute to horizontal cell responses. For a background that produced 4.76 log10photoisomerizations per rod per second (Rh*/rod/s), mean weights in superior retina were 52% (M), 2% (S), and 46% (rod). Mean weights in inferior retina were 9% (M), 50% (S), and 41% (rod). In superior retina, cone opsin weights agreed quantitatively with relative pigment density estimates from immunostaining. In inferior retina, cone opsin weights agreed qualitatively with relative pigment density estimates, but quantitative comparison was impossible because individual cones coexpress both opsins to varying and unquantifiable degrees. We further characterized the functional gradients in horizontal and brisk-transient ganglion cells using flickering stimuli produced by various mixtures of blue and green primary lights. Cone weights for both cell types resembled those obtained for horizontal cells using monochromatic flashes. Because the brisk-transient ganglion cell is thought to mediate behavioral detection of luminance contrast, our results are consistent with the hypothesis that the dual gradient of cone opsins assists achromatic contrast detection against different spectral backgrounds. In our preparation, rod responses did not completely saturate, even at background light levels typical of outdoor sunlight (5.14 log10Rh*/rod/s).
Integration of New Neurons into Functional Neural Networks
Authors: Ramirez-Amaya Victor , Marrone Diano F. , Gage Fred H. , Worley Paul F. , Barnes Carol A.
Published: November 2006

Although it is established that new granule cells can be born and can survive in the adult mammalian hippocampus, there remains some question concerning the functional integration of these neurons into behaviorally relevant neural networks. By using high-resolution confocal microscopy, we have applied a new strategy to address the question of functional integration of newborn neurons into networks that mediate spatial information processing and memory formation. Exploration-induced expression of the immediate-early geneArcin hippocampal cells has been linked to cellular activity observed in electrophysiological recordings under the same behavioral conditions. We investigated whether mature (5-month-old), newborn granule cells express Arc in response to a discrete spatial experience by detecting the expression of Arc in combination with NeuN (neuron-specific nuclear protein)-positive and bromodeoxyuridine-positive cells. We found that mature new granule cells do indeed express Arc in response to an exploration experience, supporting the idea that these cells are well integrated into hippocampal circuits. The proportion of mature newborn neurons that expressed Arc in response to exploration, however, was significantly higher (∼2.8%) than the proportion of cells that expressed Arc in the already existing population of granule cells (∼1.6%;p< 0.01). This finding extends previous data suggesting that the cellular physiology of newborn granule neurons differs from that of the existing population by indicating that these properties are retained in mature adult-generated neurons. Thus, these data have interesting implications for network models of spatial information processing and the role of hippocampal circuits in memory, indicating that mature new neurons are selectively recruited into hippocampal cell assemblies in higher proportions than older cells.
The Substantia Nigra Pars Compacta and Temporal Processing
Authors: Jahanshahi Marjan , Jones Catherine R. G. , Dirnberger Georg , Frith Christopher D.
Published: November 2006

The basal ganglia and cerebellum are considered to play a role in timing, although their differential roles in timing remain unclear. It has been proposed that the timing of short milliseconds-range intervals involves the cerebellum, whereas longer seconds-range intervals engage the basal ganglia (Ivry, 1996). We tested this hypothesis using positron emission tomography to measure regional cerebral blood flow in eight right-handed males during estimation and reproduction of long and short intervals. Subjects performed three tasks: (1) reproduction of a short 500 ms interval, (2) reproduction of a long 2 s interval, and (3) a control simple reaction time (RT) task. We compared the two time reproduction tasks with the control RT task to investigate activity associated with temporal processing once additional cognitive, motor, or sensory processing was controlled. We found foci in the left substantia nigra and the left lateral premotor cortex to be significantly more activated in the time reproduction tasks than the control RT task. The left caudate nucleus and right cerebellum were more active in the short relative to the long interval, whereas greater activation of the right putamen and right cerebellum occurred in the long rather than the short interval. These results suggest that the basal ganglia and the cerebellum are engaged by reproduction of both long and short intervals but play different roles. The fundamental role of the substantia nigra in temporal processing is discussed in relation to previous animal lesion studies and evidence for the modulating influence of dopamine on temporal processing.
Why Does Brain Damage Impair Memory? A Connectionist Model of Object Recognition Memory in Perirhinal Cortex
Authors: Cowell Rosemary A. , Bussey Timothy J. , Saksida Lisa M.
Published: November 2006

Object recognition is the canonical test of declarative memory, the type of memory putatively impaired after damage to the temporal lobes. Studies of object recognition memory have helped elucidate the anatomical structures involved in declarative memory, indicating a critical role for perirhinal cortex. We offer a mechanistic account of the effects of perirhinal cortex damage on object recognition memory, based on the assumption that perirhinal cortex stores representations of the conjunctions of visual features possessed by complex objects. Such representations are proposed to play an important role in memory when it is difficult to solve a task using representations of only individual visual features of stimuli, thought to be stored in regions of the ventral visual stream caudal to perirhinal cortex. The account is instantiated in a connectionist model, in which development of object representations with visual experience provides a mechanism for judgment of previous occurrence. We present simulations addressing the following empirical findings: (1) that impairments after damage to perirhinal cortex (modeled by removing the “perirhinal cortex” layer of the network) are exacerbated by lengthening the delay between presentation of to-be-remembered items and test, (2) that such impairments are also exacerbated by lengthening the list of to-be-remembered items, and (3) that impairments are revealed only when stimuli are trial unique rather than repeatedly presented. This study shows that it may be possible to account for object recognition impairments after damage to perirhinal cortex within a hierarchical, representational framework, in which complex conjunctive representations in perirhinal cortex play a critical role.
Molecular Markers of Neuronal Progenitors in the Embryonic Cerebellar Anlage
Authors: Morales Daniver , Hatten Mary E.
Published: November 2006

The cerebellum, like the cerebrum, includes a nuclear structure and an overlying cortical structure. Experiments in the past decade have expanded knowledge beyond the traditional function of the cerebellum to include critical roles in motor learning and memory and sensory discrimination. The initial steps in cerebellar development depend on inductive signaling involving FGF and Wnt proteins produced at the mesencephalic/metencephalic boundary. To address the issue of how individual cerebellar cell fates within the cerebellar territory are specified, we examined the expression of transcription factors, including mammalian homologues of LIM homeodomain-containing proteins, basic helix-loop-helix proteins, and three amino acid loop-containing proteins. The results of these studies show that combinatorial codes of transcription factors define precursors of the cerebellar nuclei, and both Purkinje cells and granule neurons of the cerebellar cortex. Examination of gene expression patterns in several hundred lines ofEgfp-BAC (bacterial artificial chromosome) transgenic mice in the GENSAT Project revealed numerous genes with restricted expression in cerebellar progenitor populations, including genes specific for cerebellar nuclear precursors and Purkinje cell precursors. In addition, we identified patterns of gene expression that link granule and Purkinje cells to their precerebellar nuclei. These results identify molecular pathways that offer new insights on the development of the nuclear and cortical structures of the cerebellum, as well as components of the cerebellar circuitry.