bluuebunny/crossref_metadata_2025 huggingface dataset:
Pulmonary malacoplakia in an immunocompetent girl: A case report
Authors: Kumar Prashant , Rassl D.M. , Hamilton J.R.L. , Spencer D.A.
Published: September 2003

Malacoplakia is an unusual inflammatory condition with distinctive histologic features. Involvement of the lung is quite uncommon and is rarely described in paediatrics. We report on a case of pulmonary malacoplakia in a teenage girl. Pediatr Pulmonol. 2003; 36:450–452. © 2003 Wiley‐Liss, Inc.
Social support, self‐efficacy and trauma in new recruits and experienced firefighters
Authors: Regehr Cheryl , Hill John , Knott Theresa , Sault Bill
Published: September 2003

This study compared new fire recruits in the first week of employment and following a 10‐week training period with a group of experienced firefighters. Results suggest that new firefighter recruits enter the fire service with considerable experience of exposure to critical events. Nevertheless, a significant linear relationship was found between years of experience and levels of traumatic stress and depression. Further, this study revealed that experienced firefighters had lower levels of social support and lower self‐efficacy than the new recruits. As these variables were associated with traumatic stress and depressive symptoms, it is concerning that these protective factors appear to diminish with time. Copyright © 2003 John Wiley & Sons, Ltd.
Job stress, personality, and psychological distress as determinants of somatization and functional somatic syndromes in a population of nurses
Authors: De Gucht Véronique , Fischler Benjamin , Heiser Willem
Published: September 2003

The objective of the present study was to examine the respective contribution of job stress dimensions (work demands, job control, and social support at work), personality traits (neuroticism and alexithymia), and psychological distress (anxiety and depression) to somatization in a population of nurses. Therefore, a number of logistic regression analyses were conducted, with the presence versus absence of three functional somatic syndromes (functional dyspepsia (FD), irritable bowel syndrome (IBS), and idiopathic chronic fatigue (CF) and current somatization, defined as the presence of at least two medically unexplained symptoms (median number of symptoms for the sample) and four medically unexplained symptoms (highest quartile for the sample) during the past month, as the outcome variables. The results pointed out that job stress dimensions significantly and independently contributed to IBS (job control) and CF (work demands). The personality trait neuroticism was a significant predictor of both current somatization and functional somatic syndromes, whereas alexithymia primarily predicted the presence of more severe and/or more enduring forms of somatization. Finally, three out of five outcome variables were predicted by psychological distress. Future studies should examine (a) to what extent distinct patterns of associations can be found between specific job stress dimensions on the one hand, and specific functional somatic syndromes on the other and (b) the potential interaction between job stress and personality dimensions in determining somatization. Copyright © 2003 John Wiley & Sons, Ltd.
Social support has both positive and negative effects on the relationship of work stress and alcohol consumption
Authors: Hagihara Akihito , Miller Alan S. , Tarumi Kimio , Nobutomo Koichi
Published: September 2003

Previous studies imply that certain combinations of work stressors, social support (SS), and other conditions could lead to both increased and decreased alcohol consumption. Thus, we evaluated both positive and negative influences of social support on the work stress–alcohol consumption relationship in a general population. The study design was a cross‐sectional survey. Of a probability sample of persons 25 years of age or older and living in the United States (n = 3617), subjects who drank and who were without missing values with respect to study variables were analysed (n = 967 or 94). Since previous studies have suggested the necessity of adopting the sensitivity hypothesis (i.e. different stressors require different social supports), hierarchical regression analyses were carried out to test the effects of interactions between two types of social support (e.g. family social support or out‐of‐family social support) and two types of work stressors (e.g. job psychological demand, job decision latitude) on alcohol consumption. Our analysis verified that (1) social support had both positive and negative effects on the work stress–alcohol relationship. Specifically, (2) interactions between physical activity and decision latitude, and between child support and psychological job demand were related to decreased alcohol consumption. However, (3) interactions between spouse support and decision latitude, and between informal social integration and psychological job demand, were related to increased alcohol consumption. It has been suggested that social support is not of universal benefit in reducing excessive drinking and may sometimes be a reinforcing factor. Since the external validity of these findings might be limited because of the small sample size in some analyses, further study is necessary. Copyright © 2003 John Wiley & Sons, Ltd.
Cultural and gender differences in perceiving stressors: a cross‐cultural investigation of African and Western students in Chinese colleges
Authors: Hashim Ismail Hussein , Zhiliang Yang
Published: September 2003

This study was aimed to provide basic information about stress perceptions among overseas college students in China. In addition, it was also aimed at determining whether differences exist between cultures in their ways of perceiving stressors. To attain the research goals, Study Abroad Stress Survey (SASS) was administered to 82 Africans (46 men and 36 women), and 74 Westerners (32 men and 42 women) in 11 universities in Beijing, Shanghai, and Guangzhou. Percentages of subjects' responses on SASS items were calculated to judge variations that exist between Africans and Westerners and between male and female in their perception of stressors. Results indicated that academic and interpersonal sources of stress were the most common stressors perceived by the two groups. High pressure and challenges perceived by both African and Western students were classified as daily strains. No group differences existed in subtotal perceptions for the four categories of stress measured. Group variations existed only in their sub‐divisional areas of stress. Both male and female students tend to experience the highest stress levels due to daily strains. Minor differences in perception of stressors such as attaining lower grades, missing too many classes, and working with unfamiliar peoples were concluded between male and female students. The study has suggested a need for cross‐cultural orientation of students in an effort to promote effective coping and health during a study abroad experience which will offer them an opportunity to learn and grow. Copyright © 2003 John Wiley & Sons, Ltd.
Secondary school physics teachers' conceptions of scientific evidence: An exploratory case study
Authors: Taylor Joseph A. , Dana Thomas M.
Published: September 2003

This article describes an exploratory case study of secondary school physics teachers' conceptions of scientific evidence. The nature of teachers' conceptions of evidence was derived from an analysis of data collected from 1 preservice and 2 in‐service teachers. Each teacher responded to a series of research prompts in multiple interviews and handwritten tasks. In these research prompts, the teachers thought aloud while designing experiments and critically evaluating student‐collected data as presented in hypothetical classroom scenarios. Spoken and written data were recorded. The data set was coded and analyzed using standard qualitative analysis techniques. Data from this study suggest that, while contemplating the reliability and validity of hypothetical student‐generated scientific evidence, the teachers frequently intertwined conceptions of evidence with subject matter concepts centrally relevant to the hypothetical investigation. Data also indicate that the relationship between subject matter knowledge and conceptions of evidence was more pronounced for some conceptions of evidence than for others. Results suggest that a fuller study is warranted. Suggestions for future research include exploring such relationships in other physics content areas as well as other scientific disciplines. Implications for science teacher education suggest that science and science methods courses should encourage preservice teachers to engage in original scientific research, as well as participate in peer review and critique. © 2003 Wiley Periodicals, Inc. J Res Sci Teach 40: 721–736, 2003
Encouraging and analyzing student questions in a large physics course: Meaningful patterns for instructors
Authors: Harper Kathleen A. , Etkina Eugenia , Lin Yuhfen
Published: September 2003

In a large introductory physics course, structured weekly journals (weekly reports) regularly encouraged students to ask questions about the material. The resulting questions were collected for one quarter and coded based on difficulty and topic. Students also took several conceptual tests during the quarter. The reports contained more questions than typically observed in a college classroom, but the number of questions asked was not correlated to any measure of conceptual performance. Relationships among different types of questions and performance on these tests were explored. Deeper‐level questions that focus on concepts, coherence of knowledge, and limitations were related to the variance in student conceptual achievement. © 2003 Wiley Periodicals, Inc. J Res Sci Teach 40: 776–791, 2003
A one‐dimensional analytically based approach for studying poroplastic and viscous consolidation: Application to Woodlark Basin, Papua New Guinea
Authors: Stover S. C. , Ge S. , Screaton E. J.
Published: September 2003

In the study of sedimentary basin evolution, consolidation of marine sediments has historically been characterized by applying variations on poroplastic theory. However, recent field evidence and models of deformation by pressure solution suggest that both poroplastic and viscous modes of compaction should be investigated when evaluating basin development. To study the influence of poroplastic and viscous deformation on marine sediments, we constructed a generic framework that incorporates the two modes of compaction into a numerical scheme. Analytical solutions for pressure development and porosity change based on both poroplastic and viscous theory were incorporated into this scheme, and a characteristic height was determined to indicate the depth at which viscous deformation is initiated. Application of our framework to a site in Woodlark Basin, Papua New Guinea, and comparison of the simulated results to measured porosity data suggest that poroplastic deformation is the dominant mode of consolidation at the site and that lithologic strength is controlling the observed porosity profile. Two simulated scenarios, based on different characteristic heights, showed that while a full poroplastic model may be most appropriate to characterize compaction at the site, viscous deformation may be a factor in developing the low porosities (26 to 40%) observed below 590 m below seafloor. As such, although poroplastic deformation may be predominant in basins less than 1 km deep, a combined poroplastic/viscous model may be useful to address sediments which exhibit markedly low porosity at shallow depths.
Early stages of Gondwana breakup: The 40Ar/39Ar geochronology of Jurassic basaltic rocks from western Dronning Maud Land, Antarctica, and implications for the timing of magmatic and hydrothermal events
Authors: Zhang X. , Luttinen A. V. , Elliot D. H. , Larsson K. , Foland K. A.
Published: September 2003

The timing of magmatic events forming Jurassic basaltic rocks in Dronning Maud Land (DML), Antarctica, and hydrothermal activity that affected them is addressed with detailed 40Ar/39Ar incremental heating dating of feldspars. Plagioclase from an Utpostane gabbro and from a Kirwanveggen dolerite dike yield indistinguishable plateau ages at 177 ± 1.8 Ma. Because of geologic controls, this establishes the age of tholeiites in Vestfjella. These plateau ages demonstrate synchroneity of tholeiitic magmatism of both DML and the well‐documented Ferrar Province of Antarctica, which together with the closely temporal Karoo constitute the Gondwana breakup magmatism. Vug‐filling microclines from Vestfjella yield plateau ages of 150 and 139 Ma which are interpreted to give the ages of secondary mineralization events. These results suggest a lengthy period of extension, possibly accompanied by pervasive low‐temperature hydrothermal activity, between flood basalt magmatism and inception of seafloor spreading (circa 160–165 Ma), with younger moderate temperature events recorded by K‐feldspars and related to early stages of spreading and/or changes in plate motions. The majority of plagioclase samples yield discordant age spectra that reflect primarily overprinting by younger events and incorporation of excess Ar, and they illustrate the complexities that can be produced.
Paleomagnetism of the Notch Peak contact metamorphic aureole, revisited: Pyrrhotite from magnetite+pyrite under submetamorphic conditions
Authors: Gillett Stephen L.
Published: September 2003

On the basis of new demagnetization and rock magnetic experiments, a scattered, two‐polarity remagnetization extending throughout the contact metamorphic aureole surrounding the Jurassic Notch Peak granitic stock in western Utah is now thought to reside in metamorphic pyrrhotite rather than in fine‐grained hematite. In part, the pyrrhotite formed by in situ reduction of magnetite by pyrite and organic compounds; it could not have been formed by the large‐scale introduction of reducing fluids, as isotopic evidence indicates that these metalimestones remained impermeable. At higher grades, some pyrrhotite probably also formed by the reaction of pyrite and Fe‐bearing silicates. As magnetite destruction and pyrrhotite formation extends into rocks that are not obviously metamorphosed, the reactions responsible could proceed at very low (less than ∼200°C) temperatures, and the feasibility of such low‐temperature reactions in a closed system is shown by detailed thermodynamic calculations. This study demonstrates that under reducing conditions in the presence of sufficient pyrite, pyrrhotite can form at the expense of magnetite under very mild conditions; indeed, magnetite may be destroyed merely by deep burial. Such a mechanism may help explain the paucity of primary magnetite in ancient sedimentary rocks, particularly since the single‐domain and pseudo‐single‐domain grains capable of retaining a stable paleomagnetic signature over geologic time are extremely fine‐grained and hence particularly vulnerable to destruction.
Importance of dust particles in the free troposphere over the Taklamakan Desert: Electron microscopic experiments of particles collected with a balloonborne particle impactor at Dunhuang, China
Authors: Iwasaka Y. , Shi G.‐Y. , Yamada M. , Matsuki A. , Trochkine D. , Kim Y. S. , Zhang D. , Nagatani T. , Shibata T. , Nagatani M. , Nakata H. , Shen Z. , Li G. , Chen B.
Published: September 2003

Measurements of aerosol morphology and chemical elements were made in August 2002 at Dunhuang (40°00′N, 94°30′E), China, on the basis of direct sampling of free tropospheric aerosols with a balloonborne particle impactor, to understand nature of atmospheric particles over the desert areas in the Asian continent. Electron microscopic experiments of the particles directly showed that mineral (dust) particles were major constituents of coarse mode particles in the free troposphere over the Taklamakan desert. Typical types of the particles, according to energy dispersive X‐ray (EDX) analysis, were Si‐rich and Ca‐rich particles in heights of about 3–5 km, and the ratio of those particle number to total particle number was about 0.71 in coarse mode range (diameter larger than 1.0 μm). The ammonium sulfate particles were major in fine mode range (diameter smaller than 1.0 μm). This result shows good correspondence with the lidar measurements, which were made in collaboration with this balloonborne measurements. The large depolarization ratio, according to lidar measurements, distributed from near the surface to about 6 km, suggesting that lots of particles having irregular shape (possibly dust particles) were in the free troposphere in summer over the Taklamakan desert. Trajectory analysis of air masses showed the possibility that westerly wind transported those dust particles (Kosa particles) to downwind areas even in summer season above about 5 km, which is interesting and useful information to give explanation on the aircraft measurements made at Japan, showing possible transport of dust particles in the middle and upper troposphere in summer season.
Transport and Chemical Evolution over the Pacific (TRACE‐P) aircraft mission: Design, execution, and first results
Authors: Jacob Daniel J. , Crawford James H. , Kleb Mary M. , Connors Vickie S. , Bendura Richard J. , Raper James L. , Sachse Glen W. , Gille John C. , Emmons Louisa , Heald Colette L.
Published: September 2003

The NASA Transport and Chemical Evolution over the Pacific (TRACE‐P) aircraft mission was conducted in February–April 2001 over the NW Pacific (1) to characterize the Asian chemical outflow and relate it quantitatively to its sources and (2) to determine its chemical evolution. It used two aircraft, a DC‐8 and a P‐3B, operating out of Hong Kong and Yokota Air Force Base (near Tokyo), with secondary sites in Hawaii, Wake Island, Guam, Okinawa, and Midway. The aircraft carried instrumentation for measurements of long‐lived greenhouse gases, ozone and its precursors, aerosols and their precursors, related species, and chemical tracers. Five chemical transport models (CTMs) were used for chemical forecasting. Customized bottom‐up emission inventories for East Asia were generated prior to the mission to support chemical forecasting and to serve as a priori for evaluation with the aircraft data. Validation flights were conducted for the Measurements Of Pollution In The Troposphere (MOPITT) satellite instrument and revealed little bias (6 ± 2%) in the MOPITT measurements of CO columns. A major event of transpacific Asian pollution was characterized through combined analysis of TRACE‐P and MOPITT data. The TRACE‐P observations showed that cold fronts sweeping across East Asia and the associated warm conveyor belts (WCBs) are the dominant pathway for Asian outflow to the Pacific in spring. The WCBs lift both anthropogenic and biomass burning (SE Asia) effluents to the free troposphere, resulting in complex chemical signatures. The TRACE‐P data are in general consistent with a priori emission inventories, lending confidence in our ability to quantify Asian emissions from socioeconomic data and emission factors. However, the residential combustion source in rural China was found to be much larger than the a priori, and there were also unexplained chemical enhancements (HCN, CH3Cl, OCS, alkylnitrates) in Chinese urban plumes. The Asian source of CCl4 was found to be much higher than government estimates. Measurements of HCN and CH3CN indicated a dominant biomass burning source and ocean sink for both gases. Large fractions of sulfate and nitrate were found to be present in dust aerosols. Photochemical activity in the Asian outflow was strongly reduced by aerosol attenuation of UV radiation, with major implications for the concentrations of HOx radicals. New particle formation, apparently from ternary nucleation involving NH3, was observed in Chinese urban plumes.
Numerical simulations of grassland fires in the Northern Territory, Australia: A new subgrid‐scale fire parameterization
Authors: Clark Terry L. , Griffiths Morwenna , Reeder Michael J. , Latham Don
Published: September 2003

A new subgrid‐scale parameterization is developed to incorporate the effects of wild fires into a numerical model of the atmosphere. The parameterization is written in terms of the temperature of the combusting material and the concentration of the unburned airborne fuel. There are two central assumptions on which the parameterization rests. First, the transport of oxygen into the region of combustion, which limits the rate of oxidation, is represented by Rayleigh mixing with a fixed timescale. Second, the combusting gases and the atmosphere are treated as separate fluids. For simplicity, the effects of conduction between the combusting fluid and the atmosphere are purposely not considered in this paper. This means that the grid‐scale buoyancy is defined as a volume average of the buoyancy of the combusting fluid and the ambient atmosphere, and that fire‐induced buoyancy is confined to the region containing the combusting gases. These assumptions lead to a highly simplified system capturing the essence of the combustion process. The parameterization is used in a simulation of an observed grass fire in the Northern Territory (Australia).
Spatial relation between main earthquake slip and its aftershock distribution
Authors: Das S. , Henry C.
Published: September 2003

We examine where aftershocks occur relative to the spatial distribution of the main shock slip using data from several recent large earthquakes. No universal relation between high‐ and low‐moment regions and high or low aftershock occurrence, or vice versa, is found. We generally find that few, and usually the smaller, aftershocks occur in the high‐slip regions of the fault, a notable exception to this being the great 1996 Biak, Indonesia, subduction zone earthquake. In all cases, aftershocks occur on favorably oriented planes of weakness in regions of increased postseismic stress. Generally, they are clustered at both ends of faults, but examples where aftershocks occur only at one end or where there is no clustering at the ends are found. Aftershock clusters are also found at the edge of unbroken barriers, and regions of rapid transition from high to low slip, within the main fault area. We identify examples of geometrical and inhomogeneous barriers and sharp and dull stress concentrations. Rupture in the main shock is generally found to nucleate in the region of low slip or at the edge of high‐slip regions, the 1996 Biak earthquake again being the only exception, nucleating in a very high slip region. Off‐fault aftershocks are found for all earthquakes in this study, and they sometimes rupture the nodal plane conjugate to the main shock fault plane.
Flow and transport in highly heterogeneous formations: 2. Semianalytical results for isotropic media
Authors: Fiori A. , Janković I. , Dagan G.
Published: September 2003

Flow and transport of nonreactive solutes in heterogeneous porous media is studied by adopting a multi‐indicator model of permeability structure. The porous formation is modeled as a collection of blocks of uniform permeability K implanted at random in a matrix of constant conductivity K0. The multi‐indicator model leads to simple semianalytical solutions based on the self‐consistent argument, which are valid for a high degree of heterogeneity. The methodology is applied to isotropic formations to derive a few statistical moments of the velocity field and of the solute particles trajectory as functions of time and of the log conductivity variance σY2. Along the common models of aquifer permeability distribution the distribution of Y = ln K is assumed to be normal. All the semianalytical results degenerate in the well‐known first‐order results when σY2 ≪ 1. In particular, it is shown that the first‐order longitudinal dispersivity αL seems to hold for values of the log conductivity variance much larger than expected, up to σY2 ≈ 4. This results from a compensation of errors associated with the first‐order approximation. In contrast, for σY2 ≫ 1, the asymptotic αL grows exponentially with σY2. The effect of molecular diffusion is considered in a simple manner by introducing a cutoff κC for the conductivity contrast κ. The time to reach the asymptotic αL grows with the log conductivity variance. It is thus observed that transport in highly heterogeneous formations can be characterized by a very prolonged, non‐Fickian stage, with dispersivity αL growing continuously with time. Further analysis of third‐order moment of trajectory indicates that for growing values of σY2 the time needed for the plume to become Gaussian can be quite large.
An analytical formulation of two‐dimensional groundwater dispersion induced by surficial recharge variability
Authors: Swain Eric D. , Chin David A.
Published: September 2003

A predominant cause of dispersion in groundwater is advective mixing due to variability in seepage rates. Hydraulic conductivity variations have been extensively researched as a cause of this seepage variability. In this paper the effect of variations in surface recharge to a shallow surficial aquifer is investigated as an important additional effect. An analytical formulation has been developed that relates aquifer parameters and the statistics of recharge variability to increases in the dispersivity. This is accomplished by solving Fourier transforms of the small perturbation forms of the groundwater flow equations. Two field studies are presented in this paper to determine the statistics of recharge variability for input to the analytical formulation. A time series of water levels at a continuous groundwater recorder is used to investigate the temporal statistics of hydraulic head caused by recharge, and a series of infiltrometer measurements are used to define the spatial variability in the recharge parameters. With these field statistics representing head fluctuations due to recharge, the analytical formulation can be used to compute the dispersivity without an explicit representation of the recharge boundary. Results from a series of numerical experiments are used to define the limits of this analytical formulation and to provide some comparison. A sophisticated model has been developed using a particle‐tracking algorithm (modified to account for temporal variations) to estimate groundwater dispersion. Dispersivity increases of 9 percent are indicated by the analytical formulation for the aquifer at the field site. A comparison with numerical model results indicates that the analytical results are reasonable for shallow surficial aquifers in which two‐dimensional flow can be assumed.
Climatic warming and accompanying changes in the ecological regime of the Black Sea during 1990s
Authors: Oguz Temel , Cokacar Tulay , Malanotte‐Rizzoli Paola , Ducklow Hugh W.
Published: September 2003

The Black Sea ecosystem is shown to experience abrupt shifts in its all trophic levels from primary producers to apex predators in 1995–1996. It arises as a manifestation of concurrent changes in its physical climate introduced by intensive warming of its surface waters as well as abrupt increases in the mean sea level and the net annual mean fresh water flux. The warming is evident in the annual‐mean sea surface temperature (SST) data by a continuous rise at a rate of ∼0.25°C per year, following a strong cooling phase in 1991–1993. The most intense warming event with ∼2°C increase in the SST took place during winters of the 1994–1996 period. It also coincides with 4 cm yr−1 net sea level rise in the basin, and substantial change in the annual mean net fresh water flux from 150 km3 yr−1 in 1993 to 420 km3 yr−1 in 1997. The subsurface signature of warming is marked by a gradual depletion of the Cold Intermediate Layer (characterized by T < 8°C) throughout the basin during the same period. Winters of the warming phase are characterized by weaker vertical turbulent mixing and upwelling velocity, stronger stratification and, subsequently, reduced upward nutrient supply from the nutricline. From 1996 onward, the major late winter‐early spring peak of the classical annual phytoplankton biomass structure observed prior to mid‐90s was, therefore, either weakened or disappeared altogether depending on local meteorological and oceanographic conditions during each of these years. The effect of bottom‐up limited unfavorable phytoplankton growth is reflected at higher trophic levels (e.g., mesozooplankton, gelatinous macrozooplankton, and pelagic fishes) in the form of their reduced stocks after 1995.
The balance of effects of deep convective mixing on tropospheric ozone
Authors: Lawrence Mark G. , von Kuhlmann Rolf , Salzmann Marc , Rasch Philip J.
Published: September 2003

The balance of effects that vertical transport associated with deep cumulus convection has on tropospheric O3 is discussed. We first show theoretically that convective mixing of O3 can substantially reduce its column mean lifetime over clean regions, while a much smaller increase is generally expected over polluted regions. The global chemistry‐transport model MATCH‐MPIC confirms this, computing a 6% decrease in the annual mean tropospheric O3 burden and a 7% decrease in its lifetime due to convective transport of O3 alone. We find, however, that the net effect of convective transport of all trace gases (O3 and precursors together) is a 12% increase in the tropospheric O3 burden. Thus, in contrast to previous literature, our results indicate that the enhanced O3 production due to precursor transport from polluted regions significantly outweighs the reduction in O3 lifetime due to mixing over clean regions.
Dynamics of the December 2002 flank failure and tsunami at Stromboli volcano inferred by volcanological and geophysical observations
Authors: Bonaccorso A. , Calvari S. , Garfì G. , Lodato L. , Patanè D.
Published: September 2003

The 2002 effusive flank eruption at Stromboli volcano started on December 28, after several months of strong explosive activity at the summit craters. On December 30, the seismic network recorded two large flank failures and associated tsunami waves. This is the first time that a flank collapse and tsunami, and their associated phenomena, have been recorded by a multi‐disciplinary monitoring system. Volcanological and geophysical monitoring, as well as thermal surveys performed immediately before and after the failure, allowed us to define and interpret the sequence of events. The still on‐going eruption has provided, for the first time, the opportunity to look into the dynamics of Stromboli's effusive eruptions, flank failure and landslide formation, and their potential hazard.
The influence of phase boundary deflection on velocity anomalies of stagnant slabs in the transition zone
Authors: Chambers K. , Pysklywec R. N.
Published: September 2003

Although the behavior of subducted slabs in the mantle transition zone remains uncertain, images from seismic tomography provide insight into a rather complex geodynamic evolution of slabs in this region. Using a numerical mantle convection model we consider in more detail the dynamics of subducted slabs around an endothermic phase change at 660 km depth. The time‐dependent temperature fields from the flow simulation are used to derive perturbations from a radially stratified seismic velocity model. We find that the positive velocity anomalies of the cold descending slabs may be significantly decreased at the phase change owing to the slab‐induced downward phase boundary deflection and associated velocity discontinuity across the boundary. The slab may be completely or partially rendered seismically undetectable, depending on the amount of phase boundary deflection. The results have implications for the seismic interpretation of the dynamics of subducted slabs interacting with a phase transition.
Potential predictability and extended range prediction of Indian summer monsoon breaks
Authors: Goswami B. N. , Xavier Prince K.
Published: September 2003

Extended range prediction (two to three weeks in advance) of Indian summer monsoon active (rainy) and break (dry) phases are of great importance for agricultural planning and water management. Using daily rainfall and circulation data for 23 years, a fundamental property of the monsoon intraseasonal oscillations (ISO's) is discovered and shown that the potential predictability limit (∼20 days) of monsoon breaks is significantly higher than that for active conditions (∼10 days). An empirical model for prediction of monsoon ISO's is then constructed and feasibility of useful prediction of monsoon breaks up to 18 days in advance is demonstrated.
Sensitivity of water mass transformation and heat transport to subgridscale mixing in coarse‐resolution ocean models
Authors: Gnanadesikan A. , Slater R. D. , Samuels B. L.
Published: September 2003

This paper considers the impact of the parameterization of subgridscale mixing on ocean heat transport in coarse‐resolution ocean models of the type used in coupled climate models. Increasing the vertical diffusion increases poleward heat transport in both hemispheres. Increasing lateral diffusion associated with transient eddies increases poleward heat transport in the southern hemisphere while decreasing it in the northern hemisphere. The results are interpreted in the context of a simple analytical model.
Temperatures at the base of the Laurentide Ice Sheet inferred from borehole temperature data
Authors: Rolandone Frédérique , Mareschal Jean‐Claude , Jaupart Claude
Published: September 2003

We use temperature profiles from 4 deep (>1600 m) boreholes across Canada to determine ground surface temperature histories (GSTH's) through and after the Last Glacial Maximum (LGM). Inversion yields the temperature history at the base of the glacier and the surface temperature evolution after the glacial retreat. The results indicate geographic differences in basal temperature history across the Ice Sheet. During the Last Glacial Maximum, temperatures at the base of the Ice Sheet were lower in eastern Canada, at the southeastern edge of the glacier, than in central Canada, southwest of the glacier center. At all sites, basal temperatures were above the melting point of ice during and after the LGM, which may explain the highly unstable character of the Ice Sheet. The GSTH's are consistent with information on the history of the Laurentide ice sheet and provide quantitative constraints on glacier flow dynamics.
Molecular sublayers beneath the air‐sea interface relative to momentum, heat and gas transports
Authors: Tsai Wu‐ting , Chen Shi‐Ming , Lin Mei‐Ying , Hung Li‐Ping
Published: September 2003

Numerical simulations of the wind‐driven aqueous turbulent flow and the underlying heat and dissolved gas transports are conducted with sufficiently fine grid resolution to resolve the molecular sublayers immediately beneath the air‐water interface. The simulated mean distributions of velocity, temperature and gas concentration all exhibit exponential profiles across the sublayers in accordance with the theoretical postulation of Liu and Businger [1975] which they derived on the basis of the conceptual surface renewal model. The numerical results identify two major coherent renewal processes within the flow: intermittent upwellings induced by uprising horseshoe‐like eddies in the well‐mixed region, and elongated, high‐speed, cool streaks within the sublayer reflecting the cool‐skin thermal structure.
Testing an inverse Thellier method of paleointensity determination
Authors: Dunlop David J. , Yu Yongjae
Published: September 2003

We test a new inverse Thellier method of paleointensity determination. Instead of heating‐cooling steps, it uses cooling‐heating steps below room temperature T0 to eliminate chemical alteration, a major cause of failure in the Thellier method. Inverse thermoremanent magnetization (ITRM), produced when magnetite warms from below the Verwey transition (TV = 120 K) to T0 in a field H, is a prime candidate for the inverse Thellier method. ITRM can be produced in nature if the interior of a magnetite‐bearing meteorite is <TV at impact and warms in the Earth's field. Other types of natural remanent magnetization (NRM) may be suitable for inverse Thellier treatment if their low‐temperature demagnetization (LTD) spectra resemble the ITRM spectrum. In our experiments, NRM was an ITRM produced by warming from 30 K to T0. NRM remaining after the first (zero‐field) cooling‐warming step to T was compared to partial ITRM (pITRM) produced by H (usually 0.1 mT) in the second step. NRM and pITRM values from T = 200, 150, 130, 120, 110, 100 and 90 K steps give an “inverse Arai” plot, whose slope is the ratio between the ITRM and pITRM fields. We measured magnetites with mean grain sizes of 0.065, 0.2, 1, 3, 6, 9, 17, 20 and 135 μm and two gabbros containing elongated single‐domain magnetite. Single‐domain samples had quasi‐linear inverse Arai plots but other samples had convex‐down curves, resembling Arai plots for TRM in multidomain grains. More ITRM is lost in zero‐field steps than is regained as pITRM during in‐field steps. The reason is that LTD mainly affects domain walls and highlights multidomain behavior. However, the inverse Thellier method may have more linear behavior if the NRM is a TRM because the greater resistance of TRM to LTD should offset the too‐rapid decay of ITRM in zero‐field steps.
Changes in the Northern Hemisphere annual cycle: Implications for paleoclimatology?
Authors: Jones P. D. , Briffa K. R. , Osborn T. J.
Published: September 2003

Paleoclimatologists generally consider past epochs on the basis of whether they were warmer or colder than today's climate. It is often not possible, however, to consider potential changes in the annual cycle because of limited seasonal emphases in many climate proxies. Using both long European instrumental records and longer European and Chinese documentary series, we show that winters have warmed relative to summers over the last 200 years compared to earlier in the millennium. Without more widespread data we do not know how general these changes are, but if they are applicable to other parts of the world, there are two principal implications for paleoclimatology. First, because high‐frequency climate information obtained from some proxies is more indicative of “summer” conditions, it may give erroneous indications of the past if used to reconstruct mean temperatures over the whole calendar year. Second, climate model integrations of the last millennium would be expected to produce seasonal differences on century timescales, so this measure should be used as one of the important indicators of model performance.
Vigabatrin: longterm follow‐up of electrophysiology and visual field examinations
Authors: Hardus Peter , Verduin Willem , Berendschot Tos , Postma Gina , Stilma Jan , Van Veelen Cees
Published: September 2003

Background:  To report the results of repeated electrophysiological and visual field examinations in patients with vigabatrin‐associated visual field loss (VGB‐VFL) and the relationship between these electrophysiological findings, the cumulative dose of vigabatrin and the extent of visual field loss.

Methods:  Twenty‐two eyes of 11 patients with VGB‐VFL were studied. All patients underwent surgery for therapy‐resistant epilepsy. Repeated electro‐oculograms (EOGs) and flash electroretinograms (ERGs) were made and the cumulative dose of vigabatrin and the visual field loss were recorded after a period of 37–47 months.

Results:  The visual field loss was stable in patients who had stopped vigabatrin at the time of the first examination. There was a slight increase in VFL in patients who continued vigabatrin. During the second EOG and ERG, abnormalities in scotopic and photopic a‐wave latencies and in scotopic b‐wave amplitude were found in more than 50% of patients. Only b‐wave latency became normal, while EOG, a‐wave latency, a‐wave amplitude and b‐wave amplitude stayed abnormal. The amount of VFL and the cumulative dose of vigabatrin were statistically correlated with the b‐wave amplitude, mainly photopic, found during the first and second examinations.

Conclusion:  After 4 years, EOG, flash ERG and visual field loss had not improved in patients with VGB‐VFL. The statistically significant correlation found during the first examination between the amount of VFL and the cumulative dose of vigabatrin with the (mainly photopic) b‐wave amplitude remained constant.
Corneal fluorescence in relation to genetic and environmental factors: a twin study
Authors: Kessel Line , Hougaard Jesper Leth , Kyvik Kirsten Ohm , Sander Birgit , Sørensen Thorkild I. A. , Larsen Michael
Published: September 2003

Purpose:  Corneal fluorescence is believed to be caused by advanced glycation end products formed by non‐enzymatic glycation on corneal proteins. The purpose of the present twin study was to examine whether the process is related to genetic or environmental factors.

Methods:  Corneal fluorescence was measured in 59 monozygotic and 54 dizygotic twin pairs. The influences of genetic and environmental factors were estimated using structural equation modelling.

Results:  Interindividual variation in corneal fluorescence was attributable to environmental factors, whereas the effect of genetic factors was of little or no significance. Corneal fluorescence correlated significantly with smoking habits (r = 0.38) and the 2‐hour oral glucose tolerance test response (r = 0.27), and increased with age (p < 0.0001).

Conclusion:  Fluorophore accumulation in the cornea was attributable to age and environmental effects, of which smoking was the most conspicuous identifiable factor, although glucose was also of relevance. However, the greater part of interindividual variation in corneal fluorescence remains unexplained.
Ocular side‐effects in breast cancer patients treated with tamoxifen and toremifene: a randomized follow‐up study
Authors: Parkkari M. , Paakkala A‐M. , Salminen L. , Holli K. ,   on behalf of the Finnish Breast Cancer Group (FBCG)
Published: September 2003

Purpose:  3Tamoxifen and toremifene are non‐steroidal anti‐oestrogens widely used in the treatment of advanced breast cancer and as adjuvant therapy following surgery in early stage disease. Tamoxifene has also been approved for use in reducing the incidence of breast cancer amongst high risk women. However, certain well documented adverse effects, mainly involving the reproductive organs, have been reported amongst users of both drugs. The aim of this study was to monitor the ocular side‐effects of both of these commonly used anti‐oestrogens.

Methods:  Sixty postmenopausal (age range 50–79 years) breast cancer patients were randomized into adjuvant tamoxifen or toremifene therapy groups for 3 years. Prior to commencement of medication, a thorough ocular examination was undertaken. The first follow‐up visit took place after 6 months and the remaining three at 12‐month intervals thereafter.

Results:  Sixteen patients had cataract at the first visit (seven in the tamoxifen group and nine in the toremifene group). Ten patients developed cataract during the study period (five in each group), giving annual cataract rates of 6.8% and 6.2% in the tamoxifen and toremifene groups, respectively. Three patients had macular crystals at the first visit (one in the tamoxifen group and two in the toremifene group). The crystals remained stable throughout the follow‐up. Macular drusen were diagnosed in five patients at the first ophthalmological check‐up (two in the tamoxifen and three in the toremifene group). Two patients in the toremifene group developed drusen maculopathy during follow‐up visits. Yellowish spots in the macular area were found in one tamoxifen‐treated patient at the second visit. At the final visit after 3.5 years' follow‐up the spots had disappeared. No abnormal corneal findings or keratopathy were documented during the follow‐up.

Conclusion:  We observed no serious ocular side‐effects among the 60 breast cancer patients treated with tamoxifen or toremifene over a 3.5‐year period.
Impact of environmental pollution on the eye
Authors: Saxena Rohit , Srivastava Sushma , Trivedi Deepa , Anand Eswaraiah , Joshi Sujata , Gupta Suresh Kumar
Published: September 2003

Purpose:  To study the effect of environmental toxins on the ocular surface in persons travelling through highly polluted areas of the metropolis of Delhi.

Methods:  A total of 500 apparently healthy volunteers recruited from the metropolis of Delhi were examined to establish the frequency of ocular surface disorders. All subjects underwent a slit‐lamp examination, tear break‐up time (BUT) test, Rose Bengal test, Schirmer's test and tear lysozyme level test.

Results:  Subjects in the study group had significantly higher levels of ophthalmic symptoms compared to the control group. In all, 105 (42%) and 125 (50%) subjects in the study group compared to 50 (20%) and 65 (26%) in the control group complained of redness and irritation (p < 0.05). There was no significant difference in visual acuity (VA) between the two groups, with best corrected VA being 6/9 or better in 92% of the study group and 96% of the control group. The average (±standard deviation) Schirmer's test result was 13.42±6.67 mm in the study group compared to 15.95±6.14 mm in the control group. This difference was statistically significant. The BUT was also significantly lower in the study group (12.97±6.12 seconds) compared to the control group (19.23±5.70 seconds) (p < 0.001). The Rose Bengal test and tear lysozyme activity did not show any significant difference between the two groups.

Conclusion:  According to our study, environmental conditions appear to have a very significant effect on the ocular surface. There were very high levels of subclinical ocular surface changes among persons travelling in highly polluted areas.
Evaluation of retinal haemodynamics and retinal function after application of dorzolamide, timolol and latanoprost in newly diagnosed open‐angle glaucoma patients
Authors: Arend Oliver , Harris Alon , Wolter Pia , Remky Andreas
Published: September 2003

Purpose:  The purpose of this prospective, randomized, cross‐over study was to investigate and compare the microcirculatory effects of timolol, dorzolamide and latanoprost in newly diagnosed primary open‐angle glaucoma (POAG) patients. Haemodynamics were assessed using fluorescein angiography by means of a scanning laser ophthalmoscope (SLO). Visual function and visual field indices were evaluated during all drug treatment phases.

Methods:  Fourteen patients with newly diagnosed POAG (age 55 ± 7 years; 10 male, four female) were recruited for the study. At baseline examination, blood pressure, heart rate, intraocular pressure (IOP), SLO angiograms, and contrast sensitivity (CS) were analysed. Patients then randomly received timolol, dorzolamide or latanoprost treatment for 4 weeks. Patients then returned and all procedures were repeated and assessed. Arteriovenous passage times (AVPs), peripapillary arterial and venous diameters were assessed from SLO angiograms, using digital image processing. Calculated ocular perfusion pressure was determined for each treatment phase.

Results:  Intraocular pressure was significantly lowered by each drug compared to baseline (p < 0.0001). Arteriovenous passage times were significantly shortened after dorzolamide application compared to baseline (p = 0.009), whereas neither timolol nor latanoprost treatment resulted in significant AVP changes. Peripapillary arterial and venous diameters, systolic and diastolic blood pressure, heart rate and ocular perfusion pressures were not significantly altered during any treatment phase. Contrast sensitivity testing at 6 cycles/degree (c.p.d.) revealed a significant rise after dorzolamide compared to timolol (p = 0.007).

Conclusion:  Our results suggest that dorzolamide treatment significantly shortened AVP times in newly diagnosed open‐angle glaucoma patients, whereas timolol and latanoprost had no significant effect. Given that prolonged AVP times have been associated with disease progression in glaucoma; dorzolamide treatment may benefit optic nervehead preservation by increasing ocular perfusion.