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Background Fluid overload leads to poor neonatal outcomes. Diuretics may lower the rates of mechanical ventilation (MV) and mortality in neonates with fluid overload. Methods This is a retrospective study of preterm neonates [less than or equal to] 36 weeks of gestational age (GA) in the first 14 postnatal days in a level IV NICU in 2014-2020. We evaluated the epidemiology of fluid balance in the first 14 postnatal days and its association with MV and mortality and studied the association of diuretics with fluid balance, MV, and mortality. Results In 1383 included neonates, the overall median lowest and peak fluid balances were - 7.8% (IQR: - 11.7, - 4.6) and 8% (3, 16) on days 3 (2, 5) and 13 (5, 14), respectively. Fluid balance distribution varied significantly by GA. Peak fluid balance of [greater than or equal to] 10% was associated with increased odds of MV on days 7 and 14 with highest odds ratios (OR) of MV in neonates with fluid balance [greater than or equal to] 15%. Peak fluid balance of [greater than or equal to] 15% was associated with the greatest odds of mortality. Diuretics were used more frequently in neonates with younger GA, smaller birthweight, positive fluid balance, and those on MV. Conclusions Positive fluid balance negatively impacts pulmonary status. The odds of MV and death increase significantly as peak fluid balance percentage increases in all GA groups. The impact of diuretics on MV and death in preterm neonates needs further evaluation. Graphical abstract, Author(s): Mariah L. Wright [sup.1] , Brett G. Klamer [sup.2] [sup.3] [sup.4] , Elizabeth Bonachea [sup.1] , John D. Spencer [sup.1] [sup.2] [sup.3] , Jonathan L. Slaughter [sup.1] [sup.5] [sup.6] [...]

Background Emergency departments (EDs) often rely on urinalysis (UA) to rapidly identify urinary tract infections (UTIs) in children. However, the suboptimal test characteristics of UA can lead to false-positive results. Novel urinary biomarkers may increase the diagnostic precision of UA. In this study, we compared the concentrations of 6 pre-selected proteins: BH3 interacting domain death agonist (BID), B-cell lymphoma 6 protein, ras GTPase-activating protein 1, cathepsin S (CTSS), 3-hydroxyanthranilate 3,4-dioxygenase, and transgelin-2. Methods In a pediatric ED, we prospectively enrolled 167 children with UA and urine culture collected. Pyuria was defined as either [greater than or equal to] 5 white blood cells per high-power field on microscopy or positive leukocyte esterase (LE). The urine culture was considered positive if it yielded [greater than or equal to] 50,000 colony-forming units per milliliter of any single urinary pathogen. Urine protein levels were measured by enzyme-linked immunosorbent assay and normalized to urine creatinine. Results BID was significantly higher in the UTI group compared to the culture-negative pyuria group with a mean ratio of 1.42 (95% confidence interval (CI), 1.15, 1.76) when uncorrected for creatinine concentration. When corrected for creatinine concentration, CTSS was significantly elevated in the UTI group compared to the culture-negative pyuria group with a mean ratio of 2.11 (95% CI, 1.39, 3.21). Conclusions BID and CTSS concentrations were elevated in the urine of children with UTI compared to those with culture-negative pyuria. These proteins deserve further research into their utility to serve as novel biomarkers for UTI. Graphical abstract, Author(s): Elaise B Hill [sup.1] [sup.2] , Joshua R Watson [sup.3] , Daniel M Cohen [sup.1] , David Kline [sup.4] , Andrew L Schwaderer [sup.5] , John D Spencer [sup.6] [...]

The prevalence of hypertension is increasing in pediatric populations. While clinical data and practice guidelines identify the impact of hypertension on organ dysfunction and emphasize the importance for end-organ damage screening, the bidirectional effects of pediatric hypertension on neurocognitive and psychological outcomes are understudied. The objective of this review is to highlight the association between hypertension and cognition, attention, learning, and mental health in children and adolescents. In doing so, this review provides a framework and toolkit to integrate neuropsychology and psychology into the screening and management stages of pediatric hypertension. By recognizing the effects of hypertension on cognition, behavior, and mental health, screenings and interventions can be implemented to proactively and comprehensively improve the health outcomes for children with blood pressure concerns., Author(s): Anne E. Dawson [sup.1] , Mahmoud Kallash [sup.2] , John D. Spencer [sup.2] , Camille S. Wilson [sup.1] Author Affiliations: (1) grid.240344.5, 0000 0004 0392 3476, Department of Pediatric [...]

Background Acute kidney injury (AKI) in preterm infants is associated with prolonged hospitalization and high mortality. Diuretic therapy has been used to enhance urine output in preterm infants with AKI. Treatment with diuretics, prescription patterns, and relationship with length of stay (LOS), mechanical ventilation (MV), and mortality in preterm infants who also had AKI have not been fully evaluated. Methods This multicenter retrospective study used the Pediatric Hospital Information System database. We included 2121 preterm infants with AKI diagnosis from 46 hospital Neonatal Intensive Care Units (NICUs) born Results Seventy-six percent of infants received at least one dose of diuretics (median treatment 18 days). Diuretic prescription varied significantly across hospitals and ranged from 42 to 96%. Diuretics were used more frequently in infants with younger GA and smaller birth weight. Infants with older GA who received diuretics at or before 28 days postnatally had worse survival even after adjusting for known confounders. Conclusions Preterm infants with AKI diagnosis were frequently treated with diuretics. Moreover, infants with younger GA and smaller birth weight were more likely to receive diuretics. Worse survival in infants with older GA who received diuretics could be the result of more underlying severe illness in these infants and not the cause of more severe illness. Prospective studies are needed to best determine patient safety and outcomes with diuretic treatment in preterm infants with AKI. Graphical abstract, Author(s): Tahagod H. Mohamed [sup.1] [sup.2] [sup.3] , Brett Klamer [sup.1] [sup.4] [sup.5] , John D. Mahan [sup.1] [sup.2] [sup.3] , John D. Spencer [sup.1] [sup.2] [sup.3] [sup.4] , Jonathan [...]

Nine-banded armadillos (Dasypus novemcinctus) can be naturally infected with Mycobacterium leprae and have been implicated in the zoonotic transmission of leprosy in the US states of Texas, Louisiana, Alabama, Georgia, [...]

Urinary tract infections are a severe public health problem. The emergence and spread of antimicrobial resistance among uropathogens threaten to further compromise the quality of life and health of people who develop acute and recurrent upper and lower urinary tract infections. The host defense mechanisms that prevent invasive bacterial infection are not entirely delineated. However, recent evidence suggests that versatile innate immune defenses play a key role in shielding the urinary tract from invading uropathogens. Over the last decade, considerable advances have been made in defining the innate mechanisms that maintain immune homeostasis in the kidney and urinary tract. When these innate defenses are compromised or dysregulated, pathogen susceptibility increases. The objective of this review is to provide an overview of how basic science discoveries are elucidating essential innate host defenses in the kidney and urinary tract. In doing so, we highlight how these findings may ultimately translate into the clinic as new biomarkers or therapies for urinary tract infection., Author(s): Christina Ching [sup.1] [sup.2] [sup.3] , Laura Schwartz [sup.1] [sup.2] , John David Spencer [sup.1] [sup.2] [sup.4] , Brian Becknell [sup.1] [sup.2] [sup.4] Author Affiliations: (1) grid.240344.5, 0000 0004 [...]

People with diabetes mellitus have increased infection risk. With diabetes, urinary tract infection (UTI) is more common and has worse outcomes. Here, we investigate how diabetes and insulin resistance impact the kidney's innate defenses and urine sterility. We report that type 2 diabetic mice have increased UTI risk. Moreover, insulin-resistant prediabetic mice have increased UTI susceptibility, independent of hyperglycemia or glucosuria. To identify how insulin resistance affects renal antimicrobial defenses, we genetically deleted the insulin receptor in the kidney's collecting tubules and intercalated cells. Intercalated cells, located within collecting tubules, contribute to epithelial defenses by acidifying the urine and secreting antimicrobial peptides (AMPs) into the urinary stream. Collecting duct and intercalated cell- specific insulin receptor deletion did not impact urine acidification, suppressed downstream insulin-mediated targets and AMP expression, and increased UTI susceptibility. Specifically, insulin receptor-mediated signaling regulates AMPs, including lipocalin 2 and ribonuclease 4, via phosphatidylinositol-3-kinase signaling. These data suggest that insulin signaling plays a critical role in renal antibacterial defenses., IntroductionDiabetes mellitus (DM) has become a global epidemic. According to the International Diabetes Federation, more than 415 million people worldwide have DM, and this number is expected to increase to [...]

Ribonuclease 7 (RNase 7) is an antimicrobial peptide that prevents urinary tract infections (UTI); however, it is yet unknown how RNASE7 genetic variations affect its antimicrobial activity and its mitigation of UTI risk. This study determined whether the RNASE7 SNP rs1263872 is more prevalent in children with UTI and defined how rs1263872 affects RNase 7's antimicrobial activity against uropathogenic E. coli (UPEC). We performed genotyping for rs1263872 in 2 national UTI cohorts, including children enrolled in the Randomized Intervention for Children with Vesicoureteral Reflux trial or the Careful Urinary Tract Infection Evaluation study. Genotypes from these cohorts were compared with those of female controls with no UTI. To assess whether rs1263872 affects RNase 7's antimicrobial activity, we generated RNase 7 peptides and genetically modified urothelial cultures encoding wild-type RNase 7 and its variant. Compared with controls, girls in both UTI cohorts had an increased prevalence of the RNASE7 variant. Compared with the missense variant, wild-type RNase 7 peptide showed greater bactericidal activity against UPEC. Wild-type RNase 7 overexpression in human urothelial cultures reduced UPEC invasive infection compared with mutant overexpression. These results show that children with UTI have an increased prevalence of RNASE7 rs1263872, which may increase UTI susceptibility by suppressing RNase 7's antibacterial activity., Introduction Urinary tract infections (UTI) are one of the most common bacterial infections. In children, 8% of girls will develop a UTI by 7 years of age and up to [...]

Despite its proximity to the fecal flora, the urinary tract is considered sterile. The precise mechanisms by which the urinary tract maintains sterility are not well understood. Host immune responses are critically important in the antimicrobial defense of the urinary tract. During recent years, considerable advances have been made in our understanding of the mechanisms underlying immune homeostasis of the kidney and urinary tract. Dysfunctions in these immune mechanisms may result in acute disease, tissue destruction and overwhelming infection. The objective of this review is to provide an overview of the innate immune response in the urinary tract in response to microbial assault. In doing so, we focus on the role of antimicrobial peptides--a ubiquitous component of the innate immune response. Keywords Urinary tract infection * Pyelonephritis * Innate immunity * Antimicrobial peptides * Toll-like receptors * Chemokines * Cytokines, Introduction Urinary tract infections (UTI) are one of the most common and serious bacterial infections encountered by pediatricians [1]. Estimates on the cumulative incidence of UTIs in American children indicate [...]

This study evaluates the impact of vesicoureteral reflux (VUR) on the economy and inpatient healthcare utilization in the USA. A retrospective analysis was performed on children ≤ 18 years of age, hospitalized with the principal discharge diagnosis of VUR between 2000 and 2006, using the Healthcare Cost and Utilization Project Kids' Inpatient Database. The results are stratified as follows. First, by hospitalizations: between 2000 and 2006, 6,655 ± 720 (standard error) children/year were hospitalized with VUR. Since 2003, both the length of each hospitalization and the number of hospitalizations have decreased. Second, by related procedures/diagnoses: ureteral reimplantation was the most common procedure, accounting for 89% of hospitalizations. Congenital genitourinary anomalies, disorders of the kidney/ureter/bladder, and urinary tract infections (UTI) were the most common related diagnoses. Thirdly, by hospital economics: since 2000, hospital charges for VUR increased despite decreased lengths of hospitalization. By 2006, hospital charges rose to $18,798/hospitalization, and aggregate national charges exceeded $100 million. Our results indicate that fewer children with VUR are requiring inpatient management. Children with VUR are often hospitalized for ureteral reimplantation or the management of related diagnoses. Since 2000, hospital charges for inpatient VUR management have increased. More efforts are needed to evaluate cost-effective strategies for the evaluation and management of VUR. Keywords Vesicoureteral reflux * Pediatrics * Urinary tract infection * Epidemiology * Economics, Introduction Vesicoureteral reflux (VUR), the retrograde flow of urine from the bladder into the ureter, is the most common congenital abnormality of the urinary tract in children [1, 2]. The [...]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2010.07.017 Byline: Julie A. Rathbun (a), Nathaniel J. Rodriguez (a), John R. Spencer (b) Keywords: Europa; Thermal histories; Satellites, Surfaces Abstract: The Galileo photopolarimeter-radiometer (PPR) made over 100 observations of Europa's surface temperature. We have used these data to constrain a diurnal thermal model and, thus, map the thermal inertia and bolometric albedo over 20% of the surface. We find an increased thermal inertia at mid-latitudes that is widespread in longitude and does not appear to correlate with geology, albedo, or other observables. Our derived thermophysical properties can be used to predict volatile stability across the surface over the course of a day and in planning of infrared instruments on future missions. Furthermore, while observations in the thermal infrared can and have been used to find endogenic activity, no such activity was detected at Europa. We have calculated the detection limits of these PPR observations and find that 100km.sup.2 hotspots with temperatures of 116-1200K could exist undetected on the surface, depending on the location. Author Affiliation: (a) University of Redlands, 1200 East Colton Ave., Redlands, CA 92373, United States (b) Southwest Research Institute, 1050 Walnut St., Suite 300, Boulder, CO 80302, United States Article History: Received 15 December 2009; Revised 2 July 2010; Accepted 14 July 2010

This study evaluates the impact of pediatric uninary tract infection (UTI)s on the economy and inpatient healthcare utilization in the USA. A retrospective analysis of patient demographics and hospital economics was performed on children less than 18 years of age admitted with a UTI between 2000 and 2006 using the Healthcare Cost and Utilization Project Kids' Inpatient Database. Our results were stratified as follows. Hospital admissions--nearly 50,000 children/year were admitted with a UTI. Pediatric UTIs represented 1.8% of all pediatric hospitalizations. Seventy-three percent of patients were female and 40% were under 1 year of age. Payer information--from 2000 to 2006, pediatric insurance coverage shifted from the private sector to the public sector. Hospital cost--in 2000, estimated hospital costs for UTIs were $2,858 per hospitalization and rose to $3,838 by 2006. Mean hospital charges increased from $6,279 to $10,489 per stay. By 2006, aggregate hospital charges exceeded $520 million. Our results indicate that UTIs are among the most common pediatric admission diagnoses. Hospitalization is more common in females and younger children. Since 2000, hospital charges for UTIs increased disproportionately to hospital costs. Over time, more children hospitalized with a UTI depend on public agencies to cover healthcare expense. More efforts are needed to evaluate cost-effective strategies for evaluation and treatment of UTIs. Keywords Urinary tract infection * Pediatrics * Epidemiology. Economics * Utilization review, Introduction Urinary tract infections (UTI) are one of the most common and most serious bacterial infections in children [1-3]. Estimates on the cumulative incidence of UTIs in American children indicate [...]

Objective: Knowledge of oral disease prevention should lead to better oral health outcomes. The aims were to assess the association of dental knowledge and oral health. Methods: A random sample of 45-54 year-olds from Adelaide, South Australia, was surveyed in 2004/05. Oral examinations provided data on caries. Results: A total of 879 persons returned questionnaires (response=43.8%) with 709 (80.7%) examined. The majority rated 'seeing a dentist regularly' (63.0%), 'regular brushing of teeth' (92.5%) and 'using fluoride toothpaste' (52.2%) as 'definitely important' in preventing tooth decay. The percentage of persons who had a high knowledge of tooth decay prevention was 59.9%. Multivariate analysis controlling for sex, place of birth, education and income showed (p Conclusions: Dental knowledge was associated with oral health status. Implications: Conveying of information should be one part of oral health promotion actions to improve oral health. Key words: 45-54 year-olds, dental knowledge, oral health, caries. Aust NZ J Public Health. 2010; 34:472-5 doi: 10.1111/j.1753-6405.2010.00592.x

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2010.05.019 Byline: Julie A. Rathbun (a), John R. Spencer (b) Keywords: Io; Volcanism Abstract: Since before the beginning of the Galileo spacecraft's Jupiter orbital tour, we have observed Io from the ground using NASA's Infrared Telescope Facility (IRTF). We obtained images of Io in reflected sunlight and in-eclipse at 2.3, 3.5, and 4.8[mu]m. In addition, we have measured the 3.5[mu]m brightness of an eclipsed Io as it is occulted by Jupiter. These lightcurves enable us to measure the brightness and one-dimensional location of active volcanoes on the surface. During the Galileo era, two volcanoes were observed to be regularly active: Loki and either Kanehekili and/or Janus. At least 12 other active volcanoes were observed for shorter periods of time, including one distinguishable in images that include reflected sunlight. These data can be used to compare volcano types and test volcano eruption models, such as the lava lake model for Loki. Author Affiliation: (a) University of Redlands, 1200 East Colton Ave., Redlands, CA 92373, United States (b) Southwest Research Institute, 1050 Walnut St., Suite 300, Boulder, CO 80302, United States Article History: Received 14 December 2009; Revised 24 May 2010; Accepted 25 May 2010

The extreme albedo asymmetry of Saturn's moon Iapetus, which is about 10 times as bright on its trailing hemisphere as on its leading hemisphere, has been an enigma for three centuries. Deposition of exogenic dark material on the leading side has been proposed as a cause, but this alone cannot explain the global shape, sharpness, and complexity of the transition between Iapetus' bright and dark terrain. We demonstrate that all these characteristics, and the asymmetry's large amplitude, can be plausibly explained by runaway global thermal migration of water ice, triggered by the deposition of dark material on the leading hemisphere. This mechanism is unique to Iapetus among the saturnian satellites because its slow rotation produces unusually high daytime temperatures and water ice sublimation rates for a given albedo. 10.1126/science.1177132

This study tested a dynamic field theory (DFT) of spatial working memory and an associated spatial precision hypothesis (SPH). Between 3 and 6 years of age, there is a qualitative shift in how children use reference axes to remember locations: 3-year-olds' spatial recall responses are biased toward reference axes after short memory delays, whereas 6-year-olds' responses are biased away from reference axes. According to the DFT and the SPH, quantitative improvements over development in the precision of excitatory and inhibitory working memory processes lead to this qualitative shift. Simulations of the DFT in Experiment 1 predict that improvements in precision should cause the spatial range of targets attracted toward a reference axis to narrow gradually over development, with repulsion emerging and gradually increasing until responses to most targets show biases away from the axis. Results from Experiment 2 with 3- to 5-year-olds support these predictions. Simulations of the DFT in Experiment 3 quantitatively fit the empirical results and offer insights into the neural processes underlying this developmental change. DOI: 10.1037/a0015794

Objective: To map the geographic distribution of fluoride in water supplies and child dental caries in remote Indigenous communities of the Northern Territory (NT). To examine the association between fluoride levels, household and community factors, access to services and child dental caries in these communities and to model the impact on the caries experience of children of introducing water fluoridation. Methods: Fluoride testing was conducted in 80 locations across the NT in 2001. Measures of mean caries experience for six-year-olds and 12-year-olds and community and housing-related infrastructure were obtained from records of the NT School Dental Service. Associations between community fluoride levels, community level variables and childhood caries experience and potential impact of water fluoridation were assessed using linear regression modeling. Results: Mean caries experience for six- and 12-year-olds tended to be higher in northern and eastern areas of the NT, corresponding to the distribution of low levels of natural fluoride. Several-fold more children in remote NT communities are exposed to the risks of inadequate fluoride than are exposed to excessive fluoride. Mean reticulated fluoride level was the only variable significantly associated (p Conclusions and Implications: Introduction of fluoridation of water supplies into communities with inadequate natural fluoride is a vital measure for improving the dental health of children living in remote NT communities. Key words: fluoride, dental caries, Indigenous, prevention, remote. doi: 10.1111/j.1753-6405.2009.00376.x

To authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1467-9280.2009.02329.x Byline: Jeffrey S. Johnson (1), John P. Spencer (2,3), Steven J. Luck (4,5), Gregor Schoner (6) Abstract: ABSTRACT Efficient visually guided behavior depends on the ability to form, retain, and compare visual representations for objects that may be separated in space and time. This ability relies on a short-term form of memory known as visual working memory. Although a considerable body of research has begun to shed light on the neurocognitive systems subserving this form of memory, few theories have addressed these processes in an integrated, neurally plausible framework. We describe a layered neural architecture that implements encoding and maintenance, and links these processes to a plausible comparison process. In addition, the model makes the novel prediction that change detection will be enhanced when metrically similar features are remembered. Results from experiments probing memory for color and for orientation were consistent with this novel prediction. These findings place strong constraints on models addressing the nature of visual working memory and its underlying mechanisms. Author Affiliation: (1)Department of Psychology, University of Wisconsin-Madison (2)Department of Psychology, University of Iowa (3)The Iowa Center for Developmental and Learning Sciences, University of Iowa (4)Center for Mind and Brain, University of California, Davis (5)Department of Psychology, University of California, Davis; and (6)Institut fur Neuroinformatik, Ruhr-University Article History: (R eceived 12/26/07; R evision accepted 9/27/08) Article note: Address correspondence to Jeffrey S. Johnson, Department of Psychiatry, University of Wisconsin-Madison, 6001 Research Park Blvd., Madison, WI 53719, e-mail: jsjohnson3@wisc.edu.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jecp.2008.11.006 Byline: Lynn K. Perry (a), Larissa K. Samuelson (a)(b), John P. Spencer (a)(b) Keywords: Object representation; Spatial memory; Hidden object search Abstract: This study investigated how young children's increasingly flexible use of spatial reference frames enables accurate search for hidden objects by using a task that 3-year-olds have been shown to perform with great accuracy and 2-year-olds have been shown to perform inaccurately. Children watched as an object was rolled down a ramp, behind a panel of doors, and stopped at a barrier visible above the doors. In two experiments, we gave 2- and 2.5-year-olds a strong reference frame by increasing the relative salience and stability of the barrier. In Experiment 1, 2.5-year-olds performed at above-chance levels with the more salient barrier. In Experiment 2, we highlighted the stability of the barrier (or ramp) by maximizing the spatial extent of each reference frame across the first four training trials. Children who were given a stable barrier (and moving ramp) during these initial trials performed at above-chance levels and significantly better than children who were given a stable ramp (and moving barrier). This work highlights that factors central to spatial cognition and motor planning -- aligning egocentric and object-centered reference frames -- play a role in the ramp task during this transitional phase in development. Author Affiliation: (a) Department of Psychology, University of Iowa, E11 Seashore Hall, Iowa City, IA 52242, USA (b) Iowa Center for Development and Learning Sciences, University of Iowa, Iowa City, IA 52242, USA Article History: Received 1 October 2008; Revised 20 November 2008

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2008.07.016 Byline: Oleg Abramov, John R. Spencer Keywords: Enceladus; Geological processes; Ices; Thermal histories; Volcanism Abstract: Linear features dubbed 'tiger stripes' in the south polar region of Enceladus have anomalously high heat fluxes and are the apparent source of the observed plume. Several explanations for the observed activity have been proposed, including venting from a subsurface reservoir of liquid water, sublimation of surface ice, dissociation of clathrates, and shear heating. Thermal modeling presented in this work, coupled with observations from the Cassini Composite Infrared Spectrometer (CIRS) instrument, seeks to elucidate the underlying physical mechanism by constraining vent temperatures and thermal emission sources, using a model in which the observed thermal signature results primarily from conductive heating of the surface by warm subsurface fractures. The fractures feed surface vents, which may themselves contribute to the observed thermal emission. Model variables include vent temperature, presence of a surface insulating layer, vent width, time-variable heat input, and heat sources other than the central vent. Results indicate that CIRS spectra are best fitted with a model in which the surface is heated by narrow vents at temperatures as high as 223 K. Although equally good fits can be obtained for vent temperatures in the range of 130 to 155 K if the vents are wider (180 m and 22 m respectively) and dominate the emission spectrum, these models are probably less realistic because vents with these temperatures and widths cannot supply the observed H.sub.2O vapor flux. The lack of emission angle dependence of the thermal emission when July 2005 and November 2006 CIRS observations are compared also argues against thermal emission being dominated by the vents themselves. Thus, results favor high-temperature models, possibly venting from a subsurface liquid water reservoir. However, a fracture filled with liquid water near the surface would produce significantly higher radiances than were detected unless masked by a thermally insulating surface layer. Models that best match the CIRS data are characterized by small fractions of the surface at high temperatures, which strengthens the case for the vents and/or their conductively-heated margins being the primary heat source. Models where the thermal emission is dominated by conductive heating of the surface from below by a laterally-extensive buried heat source cannot reproduce the observed spectrum. Models with a 10 cm thick upper insulating layer produce a poor match to the CIRS spectra, suggesting high thermal inertias near the tiger stripes. Finally, tiger stripe thermal emission measured by CIRS varied by less than 15% over the 16 month period from July 2005 to November 2006. Author Affiliation: Department of Space Studies, Southwest Research Institute, 1050 Walnut St., Suite 300, Boulder, CO 80302, USA Article History: Received 24 February 2008; Revised 18 July 2008; Accepted 29 July 2008

To purchase or authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1467-8624.2008.01214.x Byline: John P. Spencer (1), Sammy Perone (2) Abstract: A central controversy in developmental science, enflamed by nativist accounts, is whether development is best viewed as a series of qualitative or continuous changes. This article defends the notion of qualitative change from the perspective of dynamical systems theory (DST). Qualitative change within DST refers to the shift that occurs when a system goes from one attractor state through an instability into a different attractor state. Such changes occur on the second-to-second timescale of behavior. Thus, developmental analysis must always stay local, grounded in the real-time attractor states around which behavior is organized. This article also demonstrates that qualitative and continuous change should not be cast in opposition. They are aligned concepts that work together across multiple timescales. Author Affiliation: (1)University of Iowa and Iowa Center for Developmental and Learning Sciences (2)University of Iowa Article note: Correspondence concerning this article should be addressed to John P. Spencer, 11 Seashore Hall E, University of Iowa, Iowa City, IA 52242. Electronic mail may be sent to john-spencer@uiowa.edu.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2007.11.027 Byline: Oleg Abramov, John R. Spencer Keywords: Europa; Geological processes; Ices; Thermal histories; Volcanism Abstract: A variety of recent resurfacing features have been observed on Europa, which may produce thermal anomalies detectable by a future mission. However, the likelihood of such a detection depends on their size and lifetimes. The results of this numerical study suggest that the lifetime of a thermal anomaly associated with the emplacement of 100 m of water onto the surface of Europa is several hundred years, and [approximately equal to]10 years for 10 m of water. If warm ice is emplaced on the surface instead of liquid water, these lifetimes decrease by up to a factor of two. Exploration of model parameters indicates that a thin insulating surface layer can double thermal anomaly lifetimes, anomalies emplaced at a latitude of 80[degrees] can remain detectable nearly a factor of two longer than those at equatorial latitudes, and anomalies on the night side can remain detectable for up to [approximately equal to]20% longer than those on the day side. High temperatures are very short-lived as the surface ice cools very rapidly to below 200 K due to sublimation cooling. Assuming steady-state resurfacing, the number of detectable thermal anomalies associated with the emplacement of 100 m of water would be on the order of 10 if the typical resurfacing area is 15 km.sup.2. If recent resurfacing is dominated by chaos regions with typical areas of 100 to 1000 km.sup.2 and lifetimes of 1000 to 4000 years, the number of detectable thermal anomalies would be on the order of 1 to 10. Author Affiliation: Department of Space Studies, Southwest Research Institute, 1050 Walnut St., Suite 300, Boulder, CO 80302, USA Article History: Received 2 April 2007; Revised 11 November 2007

Decaprenylphosphoryl-D-arabinose (DPA) has been shown to be the donor of the essential D-arabinofuranosyl residues found in the cell wall of Mycobacterium tuberculosis. DPA is formed from phosphoribose diphosphate in a four-step process. The first step is the nucleophilic replacement of the diphosphate group with decaprenyl phosphate. This reaction is catalysed by the integral membrane protein 5-phospho-[alpha]-D-ribose-1-diphosphate : decaprenyl-phosphate 5-phosphoribosyltransferase (DPPR synthase). The enzyme is essential for growth and thereby an important target candidate for the development of new tuberculosis drugs. Although membrane proteins are an important subset of targets for current antibacterial agents, details about the structures and the active sites of such proteins are often not readily available by X-ray crystallography. To begin a different approach to the issue, homologues from Mycobacterium smegmatis and Corynebacterium glutamicum were expressed in Escherichia coli and shown to be active DPPR synthases. This was followed by bioinformatic analyses of the aligned sequences and then by site-directed mutagenesis of amino acids identified as likely to be important for activity. The results suggested that the enzymic synthesis of decaprenyl-phosphate 5-phosphoribose (DPPR) occurs on the cytoplasmic side of the plasma membrane. Amino acid substitutions showed that the predicted cytoplasmic N-terminal region and two cytoplasmic loops are involved in substrate binding and/or catalysis along with parts of some adjoining inner membrane regions. The enzyme lacks the classical phosphoribose diphosphate (pRpp) binding site found in nucleic acid precursor enzymes of both prokaryotes and eukaryotes but instead contains a conserved NDxxD motif required for enzymic activity. Thus, it is plausible that this DPPR synthase has a pRpp binding site that is different from that of the classical eukaryotic enzymes, and further work to develop inhibitors against this enzyme is thereby encouraged.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2007.06.025 Byline: Kandis Lea Jessup (a), John Spencer (a), Roger Yelle (b) Keywords: Io; Volcanism; Jupiter; satellites Abstract: In February 2003, March 2003 and January 2004 Pele plume transmission spectra were obtained during Jupiter transit with Hubble's Space Telescope Imaging Spectrograph (STIS), using the 0.1a[sup.3] wide slit and the G230LB grating. The STIS spectra covered the 2100-3100 A wavelength regions and extended spatially along Io's limb encompassing the region directly above and northward of the vent of the Pele volcano. The S.sub.2 and SO.sub.2 absorption signatures evident in these data indicate that the gas signature at Pele was temporally variable, and that an S.sub.2 absorption signature was present [approximately equal to]12[degrees] from the Pele vent near 6[+ or -]5 S and 264[+ or -]15 W, suggesting the presence of another S.sub.2 bearing plume on Io. Contemporaneous with the spectral data, UV and visible-wavelength images of the plume were obtained in reflected sunlight with the Advanced Camera for Surveys (ACS) prior to Jupiter transit. The dust scattering recorded in these data provide an additional qualitative measure of plume activity on Io, indicating that the degree of dust scattering over Pele varied as a function of the date of observation, and that there were several other dust bearing plumes active during the observations. We present constraints on the composition and variability of the gas abundances of the Pele plume as well as the plumes detected by ACS and recorded within the STIS data, as a function of time. Author Affiliation: (a) Department of Space Studies, Southwest Research Institute, 1050 Walnut St., Suite 300, Boulder, CO 80302, USA (b) Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85271, USA Article History: Received 14 March 2006; Revised 10 June 2007

Empirical attempts to understand connections between abstract cognition and sensori-motor processes have pointed toward an embodied view of cognition, where cognitive activity is strongly tied to sensori-motor activity. Here the authors test the ability of the cognitive system to impose structure on the world using a well-established phenomenon in spatial cognition--biases near spatial category boundaries. Results from 5 experiments suggest that participants were unable to mentally impose a spatial category boundary without perceptual support, even when explicitly instructed to do so. The authors conclude by considering the implications of these findings for abstraction within other domains of cognition. Keywords: embodied cognition, spatial recall biases, categorization

To purchase or authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1467-8624.2006.00955.x Byline: John P. Spencer (1), Melissa Clearfield (2), Daniela Corbetta (3), Beverly Ulrich (4), Patricia Buchanan (5), Gregor Schoner (6) Abstract: This paper is in memory of Esther Thelen, who passed away while President of the Society for Research in Child Development. A survey of Esther Thelen's career reveals a trajectory from early work on simple movements like stepping, to the study of goal-directed reaching, to work on the embodiment of cognition, and, ultimately, to a grand theory of development-dynamic systems theory. Four central concepts emerged during her career: (1) a new emphasis on time; (2) the proposal that behavior is softly assembled from the interaction of multiple subsystems; (3) the embodiment of perception, action, and cognition; and (4) a new respect for individuality. Esther Thelen communicated these ideas to scientists and practitioners alike, so the ultimate benefactors of her work were children. Author Affiliation: (1)University of Iowa (2)Whitman College (3)University of Tennessee (4)University of Michigan (5)Bowling Green State University (6)Ruhr-Universitat-Bochum Article note: Correspondence concerning this article should be addressed to John P. Spencer, Department of Psychology, 11 Seashore Hall E, University of Iowa, Iowa City, IA 52242. Electronic mail may be sent to john-spencer@uiowa.edu.

We present new 1.45-1.75 jam spectra of Europa's dark non-ice material with a spectral resolution ([lambda]/[delta][lambda]) of 1200, obtained by using adaptive optics on the Keck telescope to spatially separate the spectrum of the non-ice material from that of the surrounding ice-rich regions. Despite the great increase in spectral resolution over the previous best spectra of the non-ice material, taken with Galileo's near-infrared mapping spectrometer (NIMS) with [lambda]/[delta][lambda] = 66, no new fine-scale spectral structure is revealed. The smoothness of the spectra is inconsistent with available laboratory spectra of crystalline hydrated salts at Europa temperatures, but is more consistent with various combinations of non-crystalline hydrated salts and/or hydrated sulfuric acid, as have been matched to the lower-resolution NIMS spectra. Keywords: Satellites of Jupiter; Europa; Surfaces, satellite; Spectroscopy

The purpose of this study is to examine whether or not there is poorer geographic access to health care in more rural counties. Possible inequalities in health care access and [...]

Three experiments tested whether geometric biases--biases away from perceived reference axes-reported in spatial recall tasks with pointing responses generalized to a recognition task that required a verbal response. Seven-year-olds and adults remembered the location of a dot within a rectangle and then either reproduced its location or verbally selected a matching choice dot from a set of colored options. Results demonstrated that geometric biases generalized to verbal responses; however, the spatial span of the choice set influenced performance as well. These data suggest that the same spatial memory process gives rise to both response types in this task. Simulations of a dynamic field model buttress this claim. More generally, these results challenge accounts that posit separate spatial systems for motor and verbal responses. Keywords: spatial cognition, working memory, modeling, recognition, recall

We have observed about 16 absorption lines of the [v.sub.2] S[O.sub.2] vibrational band on Io, in disk-integrated 19-[micro]m spectra taken with the TEXES high spectral resolution mid-infrared spectrograph at the NASA Infrared Telescope Facility in November 2001, December 2002, and January 2004. These are the first ground-based infrared observations of Io's sunlit atmosphere, and provide a new window on the atmosphere that allows better longitudinal and temporal monitoring than previous techniques. Dramatic variations in band strength with longitude are seen that are stable over at least a 2 year period. The depth of the strongest feature, a blend of lines centered at 530.42 [cm.sup.-1], varies from about 7% near longitude 180[degrees] to about 1% near longitude 315[degrees] W, as measured at a spectral resolution of 57,000. Interpretation of the spectra requires modeling of surface temperatures and atmospheric density across Io's disk, and the variation in non-LTE [v.sub.2] vibrational temperature with altitude, and depends on the assumed atmospheric and surface temperature structure. About half of Io's 19-[micro]m radiation comes from the Sun-heated surface, and half from volcanic hot spots with temperatures primarily between 150 and 200 K, which occupy about 8% of the surface. The observations are thus weighted towards the atmosphere over these low-temperature hot spots. If we assume that the atmosphere over the hot spots is representative of the atmosphere elsewhere, and that the atmospheric density is a function of latitude, the most plausible interpretation of the data is that the equatorial atmospheric column density varies from about 1.5 x [10.sup.17] [cm.sup.-2] near longitude 180[degrees] W to about 1.5 x [10.sup.16] [cm.sup.-2] near longitude 300[degrees] W, roughly consistent with HST UV spectroscopy and Lyman-[alpha] imaging. The inferred atmospheric kinetic temperature is less than about 150 K, at least on the anti-Jupiter hemisphere where the bands are strongest, somewhat colder than inferred from HST UV spectroscopy and millimeter-wavelength spectroscopy. This longitudinal variability in atmospheric density correlates with the longitudinal variability in the abundance of optically thick, near-UV bright S[O.sub.2] frost. However it is not clear whether the correlation results from volcanic control (regions of large frost abundance result from greater condensation of atmospheric gases supported by more vigorous volcanic activity in these regions) or sublimation control (regions of large frost abundance produce a more extensive atmosphere due to more extensive sublimation). Comparison of data taken in 2001, 2002, and 2004 shows that with the possible exception of longitudes near 180[degrees] W between 2001 and 2002, Io's atmospheric density does not appear to decrease as Io recedes from the Sun, as would be expected if the atmosphere were supported by the sublimation of surface frost, suggesting that the atmosphere is dominantly supported by direct volcanic supply rather than by frost sublimation. However, other evidence such as the smooth variation in atmospheric abundance with latitude, and atmospheric changes during eclipse, suggest that sublimation support is more important than volcanic support, leaving the question of the dominant atmospheric support mechanism still unresolved. Keywords: Io; Atmospheres, Structure; Infrared observations; Radiative transfer; Spectroscopy

Damages to ships due to corrosion are very likely, and the likelihood increases with the aging of ships. Risk and reliability approaches are more and more frequently applied in design and maintenance planning. These advanced approaches require reliable data reflecting the structural condition of ships in service. Such data is scarce. This paper presents a database of corrosion wastage. It is based on over 110,000 thickness measurements recently collected from 140 trading tankers. This database is larger than most other corrosion databases in the public domain. Corrosion wastage exhibits a high level of variability. In addition to thickness measurements of individual structural members, this database also has information on hull girder's geometrical properties and strength of ships in service. Corrosion wastage has an influence on the hull girder strength. Statistical interpretations of the database are used to represent corrosion wastage in oil tankers. The severity of corrosion is ranked by three levels: slight, moderate, and severe levels corresponding respectively to 50%, 75%, and 95% cumulative probability on the database. The risks of corrosion wastage to aging ships' structural integrity are assessed using the observations of the corrosion wastage database. The investigated risks are loss of local member's strength, loss of global hull girder strength, and shortened inspection intervals. The experience database can be used in many aspects, such as design requirements for corrosion additions and wastage allowance for plate renewal, establishment of limits to hull girder strength of FPSOs, time variant reliability approach, and risk based inspection schemes. [DOI: 10.1115/1.1894404]

Dramatic changes in the brightness and shape of Jupiter's extended sodium nebula are found to be correlated with the infrared emission brightness of Io. Previous imaging and modeling studies have shown that varying appearances of the nebula correspond to changes in the rate and the type of loss mechanism for atmospheric escape from Io. Similarly, previous IR observational studies have assumed that enhancements in infrared emissions from Io correspond to increased levels of volcanic (lava flow) activity. In linking these processes observationally and statistically, we conclude that silicate volcanism on Io controls both the rate and the means by which sodium escapes from Io's atmosphere. During active periods, molecules containing sodium become an important transient in Io's upper atmosphere, and subsequent photochemistry and molecular-ion driven dynamics enhance the high speed sodium population, leading to the brightest nebulas observed. This is not the case during volcanically quiet times when omni-present atmospheric sputtering ejects sodium to form a modest, base-level nebula. Sodium's role as a 'trace gas' of the more abundant species of sulfur (S) and oxygen (O) is less certain during volcanic episodes. While we suggest that volcanism must also affect the escape rates of S and O, and consequently their extended neutral clouds, the different roles played by lava and plume sources for non-sodium species are far too uncertain to make definitive comparisons at this time. Keywords: Io; Jupiter, magnetosphere; Satellites, atmospheres; Volcanism

This paper describes a collaborative effort by industry, government, and academia to evaluate the use of design/information technology (D/IT) and to relate the degree of use to project performance. A detailed statistical analysis of 297 projects in the Construction Industry Institute database is used to produce baseline measures of performance and D/IT use. The relationship between these measures is used to assess the economic value of using the technologies. A set of projects that excelled in the use of D/IT and that scored high on performance measures is then examined. These exemplary projects provide a basis for further in-depth analyses through on-site interviews with key project representatives. The results of this study establish that projects benefit from D/IT use. Both owners and contractors can expect construction cost savings of approximately 4% by increasing the use of D/IT. For owners there is clear evidence of schedule compression as well. Although the statistical analyses do not support schedule compression benefits for contractors, findings from the on-site interviews provide anecdotal support. CE Database subject headings: Design; Information technology (IT); Performance; Project management.

Using the Hubble Space Telescope's Space Telescope Imaging Spectrograph we have obtained for the first time spatially resolved 2000-3000 [Angstrom] spectra of Io's Prometheus plume and adjoining regions on Io's anti-jovian hemisphere in the latitude range 60[degrees] N-60[degrees] S, using a 0.1' slit centered on Prometheus and tilted roughly 45[degrees] to the spin axis. The S[O.sub.2] column density peaked at 1.25 x [10.sup.17] [cm.sup.-2] near the equator, with an additional 5 x [10.sup.16] [cm.sup.-2] enhancement over Prometheus corresponding to a model volcanic S[O.sub.2] output of [10.sup.5] kg [s.sup.-1]. Apart from the Prometheus peak, the S[O.sub.2] column density dropped fairly smoothly away from the subsolar point, even over regions that included potential volcanic sources. At latitudes less than [+ or -] 30[degrees], the dropoff rate was consistent with control by vapor pressure equilibrium with surface frost with subsolar temperature 117.3 [+ or -] 0.6 K, though S[O.sub.2] abundance was higher than predicted by vapor pressure control at mid-latitudes, especially in the northern hemisphere. We conclude that, at least at low latitudes on the anti-jovian hemisphere where there are extensive deposits of optically-thick S[O.sub.2] frost, the atmosphere is probably primarily supported by sublimation of surface frost. Although the 45[degrees] tilt of our slit prevents us from separating the dependence of atmospheric density on solar zenith angle from its dependence on latitude, the pattern is consistent with a sublimation atmosphere regardless of which parameter is the dominant control. The observed drop in gas abundance towards higher latitudes is consistent with the interpretation of previous Lyman alpha images of Io as indicating an atmosphere concentrated at low latitudes. Comparison with previous disk-resolved UV spectroscopy, Lyman-alpha images, and mid-infrared spectroscopy suggests that Io's atmosphere is denser and more widespread on the anti-jovian hemisphere than at other longitudes. S[O.sub.2] gas temperatures were in the range of 150-250 K over the majority of the anti-jovian hemisphere, consistent with previous observations. SO was not definitively detected in our spectra, with upper limits to the SO/S[O.sub.2] ratio in the range 1-10%, roughly consistent with previous observations. [S.sub.2] gas was not seen anywhere, with an upper limit of 7.5 x [10.sup.14] [cm.sup.-2] for the Prometheus plume, confirming that this plume is significantly poorer in [S.sub.2] than the Pele plume ([S.sub.2]/S[O.sub.2] < 0.005, compared to 0.08-0.3 at Pele). In addition to the gas absorption signatures, we have observed continuum emission in the near ultraviolet (near 2800 [Angstrom]) for the first time. The brightness of the observed emission was directly correlated with the S[O.sub.2] abundance, strongly peaking in the equatorial region over Prometheus. Emission brightness was modestly anti-correlated with the jovian magnetic latitude, decreasing when Io intersected the toms centrifugal equator. Keywords: Io; Satellites; Atmospheres; Spectroscopy

A careful survey of Galileo SSI global monitoring images revealed more than 80 apparent surface changes that took place on Io during the 5 year period of observation, ranging from giant plume deposits to subtle changes in the color or albedo of patera surfaces. Explosive volcanic activity was discovered at four previously unrecognized centers: an unnamed patera to the south of Karei that produced a Pele-sized red ring, a patera to the west of Zal that produced a small circular bright deposit, a large orange ring detected near the north pole of Io, and a small bright ring near Io's south pole. Only a handful of Io's many active volcanoes produced large scale explosive eruptions, and several of these erupted repeatedly, leaving at least 83% of Io's surface unaltered throughout the Galileo mission. Most of the hot spots detected from SSI, NIMS and ground-based thermal observations caused no noticeable surface changes greater than 10 km in extent over the five year period. Surface changes were found at every location where active plumes were identified, including Acala which was never seen in sunlight and was only detected through auroral emissions during eclipse. Two types of plumes are distinguished on the basis of the size and color of their deposits, confirming post-Voyager suggestions by McEwen and Soderblom [Icarus 55 (1983) 191]. Smaller plumes produce near-circular rings typically 150-200 km in radius that are white or yellow in color unless contaminated with silicates, and frequently coat their surroundings with frosts of fine-grained S[O.sub.2]. The larger plumes are much less numerous, limited to a half dozen examples, and produce oval, orange or red, sulfur-rich rings with maximum radii in the north-south direction that are typically in the range from 500 to 550 km. Both types of plumes can be either episodic or quasi-continuous over a five year period. Repeated eruptions of the smaller S[O.sub.2]-rich plumes likely contribute significantly to Io's resurfacing rate, whereas dust ejection is likely dominated by the tenuous giant plumes. Both types of plume deposits fade on time-scales of months to years through burial and alteration. Episodic seepages of S[O.sub.2] at Haemus Montes, Zal Montes, Dorian Montes, and the plateau to the north of Pillan Patera may have been triggered by activity at nearby volcanic centers. Keywords: Io; Volcanism; Surfaces; Satellite

We examine the dynamic optimization problem for not-for-profit financial institutions (NFPs) that maximize consumer surplus, not profits. We characterize the optimal dynamic policy and find that it involves credit rationing. Interest rates set by mature NFPs will typically be more favorable to customers than market rates, as any surplus is distributed in the form of interest rate subsidies, with credit rationing being required to prevent these subsidies from distorting loan volumes from their optimal levels. Rationing overcomes a fundamental problem in NFPs; it allows them to distribute the surplus without distorting the volume of activity from the efficient level.

People use geometric cues to form spatial categories. This study investigated whether people also use the spatial distribution of exemplars. Adults pointed to remembered locations on a tabletop. In Experiment 1, a target was placed in each geometric category, and the location of targets was varied. Adults' responses were biased away from a midline category boundary toward geometric prototypes located at the centers of left and right categories. Experiment 2 showed that prototype effects were not influenced by cross-category interactions. In Experiment 3, subsets of targets were positioned at different locations within each category. When prototype effects were removed, there was a bias toward the center of the exemplar distribution, suggesting that common categorization processes operate across spatial and object domains.

New 4800-7200 [Angstrom] spectra of Saturn's rings, and the icy saturnian satellites Enceladus, Tethys, Dione, Rhea, and Iapetus, do not show the weak 5773 and 6275 [Angstrom] absorption bands due to high-density condensed 02 that are seen, with a maximum depth of 1.8%, on Ganymede's trailing side. The 5773 [Angstrom] band depth must be [less than or equal to]0.6% (and very probably [less than or equal to]0.3%) on the rings, Tethys, Dione, Rhea, and the trailing side of Iapetus, and [less than or equal to] 1.2% on the trailing side of Enceladus. The lack of detectable absorption does not rule out abundant [O.sub.2] molecules that are separated too well to produce these absorption bands. The observations show that the presence of [O.sub.3], recently detected on Rhea and Dione (Noll et al. 1997b, Nature 388, 45-47), does not require the presence of detectable quantities of high-density [O.sub.2]. I discuss the implications of the new observations for models of [O.sub.2] formation on Ganymede. Key Words: Satellites of Saturn; spectroscopy; satellites of Jupiter; radiation chemistry; surfaces, satellite.

To help constrain the spatial variation of oxygen on Jupiter's satellite Ganymede,and hence have more clues to its mode of production and stability, we have obtainedspectral data from the Faint Object Spectrograph (FOS) for a single pole-to-polelatitudinal strip, along with several Wide Field Planetary Camera 2 (WFPC2) imagesin three narrow band visible filters. All observations were made of the trailinghemisphere. In the FOS data we observe both visible absorptions at 0.577 and 0.627[[micro]meter], associated with dense-phase oxygen (compressed gases, liquids, orsolids). Filter options limited the WFPC2 observations to wavelengths near theweaker oxygen absorption at 0.627 [[micro]meter]. These observations suggest thatthe dense-phase or dimer oxygen form is predominantly found in equatorial andmid-latitudes. The spectroscopic absorption feature appears in both bright and darkterrains but may be somewhat weaker in dark regions, which is consistent with thesmaller mean photon path length in the surface in darker areas. Therefore, theabundance of oxygen appears more dependent on latitude and longitude constraintsthan surface albedo. At the highest latitudes, where the ratio spectra have astrong upturn toward the blue, the oxygen bands do not appear. This relationsuggests that dimer oxygen and ozone (as seen by Galileo) have opposite trends withlatitude. Possible causes include competition or variation in the preferred stableform, which depends on temperature, solar ultraviolet flux, and/or surface age;enhancement of [O.sub.3] at the poles due to plasma interactions; or viewinggeometry effects that reduce the oxygen features at the poles when observed fromEarth. The predominantly equatorial feature supports the production of [O.sub.2]through plasma bombardment and favors defect trapping over physical adsorption ofthe dimer molecules in the surface. We briefly consider the implications ofGanymede's magnetosphere for our understanding of [O.sub.2] and [O.sub.3]distribution on Ganymede.