bluuebunny/crossref_metadata_2025 huggingface dataset:
Controlling for provider of treatment in the modelling of respiratory disease risk near cokeworks
Authors: Bottle Alex , Wakefield Jon
Published: September 2004

The improved quality of hospital admissions data makes them a valuable resource for researchers. However, we show that, when multiple providers of health care are considered, the provider (in this case hospital) may act like other confounders such as socio‐economic status, and hence must be controlled for. Such control is not as straightforward as for conventional confounders, however, but we describe a method that is appropriate under certain assumptions. We also describe a number of other statistical issues, such as the modelling of spatial and non‐spatial overdispersion, that arose during the use of hospital data in a study to investigate the possible adverse health effects of living in proximity to six cokeworks groups in England and Wales. The outcome data that we consider consist of hospital admissions for all respiratory disease in the under‐5s. The ecological level of the analysis is the census‐defined enumeration district, and the main (proxy) exposure measure utilised is the spatial location of the enumeration district population‐weighted centroid in relation to the cokeworks. We focus on the Teesside cokeworks group, for which we also had sulphur dioxide measurements from dispersion modelling as an alternative exposure measure. The major local providers varied appreciably in their standardized admission ratios for respiratory disease, and when provider was controlled for, the size of the observed excess risk found close to the cokeworks was decreased, making control for the provider of health care vital. However, the presence of multiple pollution sources, in addition to the usual shortcomings of ecological studies, makes interpretation difficult. Copyright © 2004 John Wiley & Sons, Ltd.
Designing follow‐up intervals
Authors: Raab G. M. , Davies J. A. , Salter A. B.
Published: September 2004

When an examination is needed to determine if an event has occurred there will be a loss of efficiency in using the resulting interval‐censored data instead of the exact event times. In designing follow‐up intervals this loss for longer intervals needs to be weighed against extra visits required by shorter intervals. We obtain results to quantify this for the estimation of the median and mean survival and for covariates in parametric regression models with equally spaced examination times. Asymptotic information loss for the log‐normal and Weibull distributions are similar when comparisons are made between corresponding members of the two families. For distributions with coefficients of variation of 50 per cent or more, a choice of interval from 0.25 to 0.7 times the median is recommended. Copyright © 2004 John Wiley & Sons, Ltd.
Including a time‐of‐year effect in the analysis of a matched case‐control study
Authors: Stallard Nigel , Tombs Lee
Published: September 2004

Motivated by a matched case‐control study to investigate potential risk factors for meningococcal disease amongst adolescents, we consider the analysis of matched case‐control studies where disease incidence, and possibly other risk factors, vary with time of year. For the cases, the time of infection may be recorded. For controls, however, the recorded time is simply the time of data collection, which is shortly after the time of infection for the matched case, and so depends on the latter.

We show that the effect of risk factors and interactions may be adjusted for the time of year effect in a standard conditional logistic regression analysis without introducing any bias. We also show that, if the time delay between data collection for cases and controls is constant, provided this delay is not very short, estimates of the time of year effect are approximately unbiased. In the case that the length of the delay varies over time, the estimate of the time of year effect is biased. We obtain an approximate expression for the degree of bias in this case. Copyright © 2004 John Wiley & Sons, Ltd.
Joint modelling of multivariate longitudinal profiles: pitfalls of the random‐effects approach
Authors: Fieuws Steffen , Verbeke Geert
Published: September 2004

Due to its flexibility, the random‐effects approach for the joint modelling of multivariate longitudinal profiles received a lot of attention in recent publications. In this approach different mixed models are joined by specifying a common distribution for their random‐effects. Parameter estimates of this common distribution can then be used to evaluate the relation between the different responses. Using bivariate longitudinal measurements on pure‐tone hearing thresholds, it will be shown that such a random‐effects approach can yield misleading results for evaluating this relationship. Copyright © 2004 John Wiley & Sons, Ltd.
A parametric survival model with an interval‐censored covariate
Authors: Langohr Klaus , Gómez Guadalupe , Muga Robert
Published: September 2004

We present a parametric survival model whose particularity consists in the inclusion of an interval‐censored covariate. The methodology is motivated by a study on injecting drug users in Badalona (Spain), most of whom suffered HIV infection as a result of their drug addiction. The study aims to examine the possible association between the elapsed time from first injecting drug use until HIV infection and the subsequent AIDS incubation period. Whereas the moment of HIV infection cannot be observed exactly and is therefore interval‐censored, time until AIDS onset is doubly‐censored. For the maximization of the resulting likelihood function, we use a numerical solver. Maximization is carried out by means of the mathematical programming language AMPL. Copyright © 2004 John Wiley & Sons, Ltd.
Market reactions to announcements of corporate downsizing actions and implementation strategies
Authors: Nixon Robert D. , Hitt Michael A. , Lee Ho‐Uk , Jeong Eui
Published: September 2004

This study examines the effects of downsizing actions and implementation strategies on market performance. While downsizing actions reduce costs, they also produce a loss of valuable human capital that can exceed the benefits resulting from the lay‐offs. In support of this argument, the results showed that downsizing had a negative effect on market returns and the effects grow increasingly negative with larger downsizing actions. However, the market reacts more positively to downsizing actions when reallocation strategies are used and to large downsizing actions when disengagement incentives are applied. The results of this research suggest the importance of carefully managing valuable resources to create positive returns. Copyright © 2004 John Wiley & Sons, Ltd.
Proinflammatory cytokines and other indications of inflammation in cervico‐vaginal secretions and preterm delivery
Authors: Torbé A. , Czajka R.
Published: September 2004

Objectives

To compare the usefulness of evaluating cervico‐vaginal concentrations of proinflammatory cytokines (interleukin [IL]‐1α, IL‐1β, IL‐6 and IL‐8) and procalcitonin (PCT), as well as serum levels of C‐reactive protein (CRP), leucocytosis and band form granulocytes in the prediction of preterm delivery (PTD).

Methods

A total of 65 pregnant women experiencing preterm labor (PTL) were enrolled in the study. Concentrations of the studied markers in women who delivered prematurely and in women who, after treatment, delivered at term were compared. Receiver operator characteristic (ROC) curve analysis was used for all study parameters.

Results

Cervico‐vaginal IL‐6 and procalcitonin as well as serum CRP concentrations were higher in women who delivered prematurely than in those who delivered near term. A cervico‐vaginal IL‐6 level greater than 660 pg/ml was the best predictive value of preterm delivery (sensitivity, 50%; specificity 90%; positive predictive value [PPV], 85%; NPV, 62%; likelihood ratio, 5.17). Moreover, the area under the ROC curve of 0.75 for cervico‐vaginal IL‐6 was greater than for other markers.

Conclusion

Although cervico‐vaginal concentrations of procalcitonin and serum concentration of CRP are higher in women who deliver prematurely, only cervico‐vaginal concentration of IL‐6 is a good predictor of preterm delivery.
In vivo kinematics of the ACL during weight‐bearing knee flexion
Authors: Li Guoan , DeFrate Louis E. , Rubash Harry E. , Gill Thomas J.
Published: September 2004

No study has investigated the three‐dimensional morphological changes of the anterior cruciate ligament (ACL) during functional activities in vivo. The purpose of this study was to analyze the elongation, rotation (twist), and orientation of the ACL during weight‐bearing flexion in five human subjects using dual‐orthogonal fluoroscopic images and MR image‐based computer models. The ACL consistently decreased in length with flexion. At 90°, the length decreased by 10% compared to its length at full extension. The ACL twisted internally by only 20° at 30° of flexion. The ACL was oriented more vertically (approximately 60°) and slightly laterally (approximately 10°) at low flexion angles. These data on in vivo ligament elongation demonstrate that the ACL plays a more important role in lower flexion angles than at higher flexion angles during weight‐bearing flexion. These data also suggest that successful ACL reconstruction should not only restore the ligament's elongation behavior, but also its rotational and orientation characteristics, so that normal ACL biomechanics are restored. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Singapore, grammar, and the teaching of ‘internationally acceptable English’
Authors: McArthur Tom
Published: September 2004

A consideration of the place of, and options for, explicitly teaching grammar to learners of English as an international language. A development of the opening address given at a conference on the teaching of grammar at the Regional Language Centre (RELC) in Singapore in November 2003. The key issue of the conference was whether the English-language skills of Singaporean school leavers would be improved through a revival of explicit and formal grammar teaching in the Lion City's 21st-century classrooms. The paper addresses this issue in both current and historical terms, going back indeed, at the end, to the beginnings of Western-style grammar teaching among the Greeks. While doing this, however, it also considers the nature and role of what the Singaporean government takes to be the proper target for its future citizens: speaking and writing an internationally acceptable English.
The psychic rewards of teaching
Authors: Alatis James E.
Published: September 2004

A interview conducted by William P. Ancker. The interview took place at the Intercultural Center at Georgetown University in Washington DC, 9 October 2003, and appeared in the April 2004 issue of the journal English Teaching Forum (edited by Max Koller and published by the U.S. Department of State, for teachers of English world-wide). We reproduce it here with thanks.
The faces and facets of English in Malaysia
Authors: Rajadurai Joanne
Published: September 2004

A discussion of both the selection and significance of sub-varieties of English in Malaysia. Malaysia is a multi-racial country, with a diversity of languages that includes Bahasa Malaysia (the national language), English (introduced during the colonial period from the late-eighteenth to mid-twentieth centuries), and a number of Chinese dialects, Indian languages, and other minority languages. Despite this complex linguistic tapestry, English continues to command considerable respect and prestige, and demonstrates an impressive range of intra- and international uses. It is a vehicle of communication within and across diverse linguistic and cultural groups at many levels of interaction, but clusters mainly around particular domains of use. It is important to the educational endeavours of the people and the technological, economic, and political aspirations of the nation.
Is the devil in the details? Jennifer Speake (ed.), 2003, The Oxford Dictionary of Proverbs, Oxford University Press (pp.xiv + 375. hb 0-19-860524-2)
Authors: Allen Robert
Published: September 2004

‘Proverbs and idioms are never used by people of education,’ Mrs Gaskell makes Molly Gibson's genteel stepmother say towards the end of Wives and Daughters (1866), in shocked response to Molly's description of the Squire's son as ‘the apple of his eye’. Nonetheless, proverbs abound in the pages of 19th-century literature (including Mrs Gaskell herself), providing a convenient way of identifying characters' attitudes and feelings concisely and colourfully.
Environmental and maternal correlates of foetal sex ratios in the African buffalo (Syncerus caffer) and savanna elephant (Loxodonta africana)
Authors: Visscher D. R. , van Aarde R. J. , Whyte I.
Published: September 2004

Many species exhibit skewed sex ratios at birth. Here we investigate the relationships between environmental and maternal variables (as surrogates for maternal condition) and foetal sex in African buffalo Syncerus caffer and elephant Loxodonta africana of the Kruger National Park, South Africa. Using logistic regression no significant effect was found of year, maternal lactational status, maternal age, rainfall or density on foetal sex ratio. Using a subset of our data, it was also concluded that maternal body condition did not affect foetal sex ratio in buffalo. Our analyses failed to support hypotheses predicting that mothers will skew the sex ratios of their offspring in relation to their body condition. In this study, buffalo and elephant produced offspring with a sex ratio close to parity. Our results are discussed in light of the implications for testing such hypotheses in analyses of population level.
Sexual selection on male body size and assortative pairing in Gammarus pulex (Crustacea: Amphipoda): field surveys and laboratory experiments
Authors: Bollache L. , Cézilly F.
Published: September 2004

Variation in size‐assortative pairing was studied in relation to sexual selection on male body size in the amphipod Gammarus pulex, using both transverse and longitudinal surveys of natural populations. In addition, the influence of male–male competition on size‐assortative pairing was tested in the laboratory. In both surveys, the intensity of sexual selection was positive and significant for male body size but not for females, and size‐assortative pairing was positive and significant. The magnitude of size‐assortative pairing, however, varied significantly between populations. The magnitude of size‐assortative pairing was positively correlated with the intensity of sexual selection on male body size in both surveys. In the laboratory, the strength of size‐assortative pairing decreased with decreasing male:female ratio. Taken together our results point to a role of interference competition between males in promoting patterns of size‐assortative pairing in G. pulex, although alternative explanations (i.e. female resistance) cannot be excluded.
Reproductive system of the giant squid Architeuthis in South African waters
Authors: Hoving H. J. T. , Roeleveld M. A. C. , Lipinski M. R. , Melo Y.
Published: September 2004

The reproductive system is described from 15 giant squid Architeuthis sp., collected between 1972 and 2002 in South African waters. Distinctive features of the male reproductive system are the long muscular terminal organ, with elaboration of the anterior end, and modification of the tips of the ventral arms, probably hectocotilization. The spermatophoric organ has a long finishing gland that extends from the base of the gill. The terminal organ is differentiated internally into three distinct parts, involved in the guidance, storage, protection, expulsion and possibly the coating of spermatophores. Length of spermatophores in the terminal organ varied considerably. Several stages of spermatophores were found, from tentative to false to fully formed spermatophores, within a single animal. Distinctive features of the female reproductive system are a mesentery surrounding the main blood vessels of the ovary and attaching the ovary to the dorsal gladius chamber, multiple branching (at least three times) of the genital aorta that supplies the developing oocytes, high potential fecundity (3.5–6.2 ± 106 oocytes), small eggs and short oviducts that suggest intermittent (extended) spawning. Large concentrations and single spermatangia were found in various places in females, indicating non‐specific deposition. The transfer of spermatophores is probably rapid, perhaps because of considerable sexual size dimorphism (at maturity, males are much smaller than females). Implants in males are probably self‐induced since the majority were found within reach of the terminal organ opening (primarily on the ventral arms in males).
Field observations of extended locomotor activity at sub‐optimal body temperatures in a diurnal heliothermic lizard (Tiliqua rugosa)
Authors: Kerr Gregory D. , Bull C. Michael
Published: September 2004

The behavioural response of the sleepy lizard Tiliqua rugosa to an extended drought was examined in spring and summer 2002. Observations of the behaviour and use of microhabitat by radio‐tagged lizards for spring in 2000–2002 showed that the lizards in 2002 suffered decreased body mass and increased mortality, were less active, showed reduced mating behaviour and increased use of burrows when compared with the more normal wetter years of 2000 and 2001. The lizards lost significant mass owing to dehydration and starvation. An ‘onboard’ data logger recorded lizard stride frequency and body temperature continuously for 4 months on 11 lizards during the drought of 2002. The normally diurnal heliothermic sleepy lizards responded to rare rainfall events during the drought whenever they occurred, day or night, by emerging from burrows or other shelters for extended periods of activity with sub‐optimal body temperatures as low as 8.5°C. They moved more often, and with higher stride frequencies during periods of rain than during dry periods, both overnight and during the day. As a consequence of this extended activity under physiological stress, the lizards were able to respond to naturally occurring transient opportunities for food and water that would not have been available if they were only active at optimal body temperatures. In an area where freestanding water is rarely available, the lizards were able to access limited water by licking substrate. They also gained water and perhaps nutrition by consuming the temporarily rehydrated thalli of the free‐living terrestrial cyanobacterium Nostoc commune. Such behaviour enabled lizards to regain much of the mass lost before the rainfall and probably enabled many lizards to survive until more normal food sources became available. These rare events may have a significant effect on the shaping of the sleepy lizards phenotypic capacities outside routine day‐to‐day activities.
Colonial Takao: the making of a southern metropolis
Authors: TAYLOR JEREMY E.
Published: September 2004

This article explores the relationship between colonial ideologies and urban planning in the context of the pre-war Japanese empire. It does so by examining the second largest city in what was Japan's first formal overseas colony of Taiwan. By exploring some of the key texts through which the city of Takao (Kaohsiung) was depicted and its future debated in the colonial era, the ways in which imperial ideologies, such as the ‘southern advance’ of the Japanese empire, influenced and were reflected in urban space will be considered.
Cleanliness and squalor in inter-war Tel-Aviv
Authors: HELMAN ANAT
Published: September 2004

Pressures for cleanliness in inter-war Tel-Aviv stemmed from the British government, the autonomous Jewish Municipality, local residents and visiting Zionists. This article reconstructs Tel-Aviv's sanitation during the 1920s and 1930s, describes and analyses attempts to clean the urban public space and their limited success. It is argued that the sanitary reality and the issue of cleanliness and squalor in Tel-Aviv, ‘The First Hebrew City’, reflected British colonial policies, Zionist national ideologies, ethnic and social stereotypes.
Changchun: unfinished capital planning of Manzhouguo, 1932–42
Authors: GUO QINGHUA
Published: September 2004

The rise and decline of Changchun is examined focusing on its urban character in terms of symbolic identity and built form. Based on an analysis of physical characteristics of the urban fabric and architectural forms of the state buildings, the study explores and identifies the ideological underpinnings of city planning and the methodological sources of architectural design to understand how the city was shaped and why.
Urban growth in India AD 600–1200: a comment
Authors: FRASCH TILMAN
Published: September 2004

The article tries to identify the factors that led to urban growth in India in the period we style ‘early medieval India’, viz the centuries between the decline of the Gupta empire and the rise of the Islamic sultanates in northern India. In doing so, the author obviously responds to the seminal work of R.S. Sharma, without, however, even mentioning it. Sharma is one of the most influential advocates of the school of ‘Indian feudalism’, and he linked the decline of cities in India during the period under review to the decline of long-distance trade (caused especially by the decline of Roman trade with India) on the one hand and the feudal transformation of agrarian relations on the other. The economic crisis (the emphasis on which easily identifies Sharma as a staunch Marxist) went along with a socio-religious crisis, during which people expected the fourth age of Hinduism, the age of Kali, to draw to a close. Thakur does not deny the importance of economic factors completely, but tries to weigh them against other factors, which he styles ‘technological and ecological’ and ‘institutional and political’. His conclusion in this respect is somewhat inconclusive as ‘no single factor initiated urban growth’, though in a surprising move, he adds that three phases can be made out which are characterized by agrarian expansion (AD 600–750), emergence of empires (750–1000 – this phase is obviously related to the institutional and political factors) and finally the predominance of trade (1000–1200). In what sense this development is based on ‘mechanisms’ (as alluded to in the title), remains completely open.
Genetic manipulation of drug sensitivity in haematopoietic cells
Authors: Southgate Thomas , Fairbairn Leslie J.
Published: September 2004

The haematopoietic system can be manipulated genetically to increase either its resistance to drugs or its sensitivity to certain agents. Gene transfer and expression of specific drug-resistance factors might protect haematopoietic function during antitumour chemotherapy, or allow enrichment of gene-modified cells in vivo. By contrast, gene transfer of a prodrug activator, to confer sensitivity to otherwise nontoxic prodrugs, might allow deletion of engrafted cells in the event of an adverse effect such as graft-versus-host disease or the induction of a neoplasm. In addition, expression of a prodrug activator in tumour-infiltrating haematopoietic cells could provide a means of specifically activating a cytotoxic agent within a tumour mass.
Motion and orientation of magnetic field dips and peaks in the terrestrial magnetosheath
Authors: Horbury T. S. , Lucek E. A. , Balogh A. , Dandouras I. , Rème H.
Published: September 2004

Using data from the four Cluster spacecraft, estimates of the motion of isolated magnetic field dips and peaks in the magnetosheath are presented. Their motion and orientation are deduced using four‐spacecraft timing, with typical spacecraft separations of ∼100 km. A set of 39 clear isolated dips and 12 peaks, spread over 4 days, is considered. The calculated velocities in the plasma frame are scattered around zero, with a width of ∼30 km/s and an average absolute value of 21 km/s. This places an upper limit on the speed of these structures, and within timing errors these values are consistent with the structures being stationary in the plasma frame. Two events had estimated speeds of over half the local Alfvén speed; it is shown that these two estimates were unreliable as a result of uncertainties in timings. The inferred propagation speeds were typically slower than local wave speeds (95% less than half the local Alfvén speed), even allowing for their orientations (85% less than the slow mode speed and 56% less than half of it). These results are consistent with the structures being stationary in the plasma frame, as expected for mirror modes, rather than being propagating waves or solitons. In addition, they are not consistent with structures standing in the flow. However, it is not possible to eliminate the possibility that a small number of the structures may have been slowly propagating. The normals of the structures deduced from the timings suggest that they are cylinders rather than sheets and that the maximum variance direction is a reliable estimate of their axis orientation, with a precision of ∼20° for maximum/intermediate eigenvalue ratios of 10 or more.
Impact of the 1997/98 ENSO on upper ocean characteristics in Marguerite Bay, western Antarctic Peninsula
Authors: Meredith Michael P. , Renfrew Ian A. , Clarke Andrew , King John C. , Brandon Mark A.
Published: September 2004

A year‐round sequence of hydrographic casts is used to trace the evolution of the upper ocean waters in Marguerite Bay, western Antarctic Peninsula (wAP), between 1998 and 2002. Winter 1998 was anomalous, showing an unusually deep mixed layer that became progressively more saline until spring, reaching salinities as high as 34.0. The remnant of this mixed layer (the Winter Water, WW) was the deepest and most saline observed. Atmospheric and cryospheric conditions were anomalous during winter 1998 at both local and regional scales. Locally, we observed low sea ice concentrations, high air temperatures, and a high frequency of northerly winds. These are the local manifestations of the strong ENSO event of 1997/1998 that was then rapidly weakening. At the regional scale, this ENSO produced significant anomalies in the sea ice distribution throughout the Amundsen‐Bellingshausen Sea area, and a large‐scale low‐pressure anomaly over the southeast Pacific was seen to be responsible for the warm, northerly winds. We use a coupled mixed‐layer/ice production model to investigate the ENSO‐driven forcings for the anomalous ocean conditions observed in winter 1998. This reveals that ice production is the main control on upper ocean stratification, and that the deep, saline mixed layer in 1998 was forced by anomalous sea ice conditions on spatial scales larger than purely local. We conclude that the near‐coastal hydrography along the Peninsula shows a profound response to ENSO, with atmospheric and cryospheric forcings both implicated.
Reconstruction of the flanks of the Mid‐Atlantic Ridge, 28° to 29°N: Implications for evolution of young oceanic lithosphere at slow‐spreading centers
Authors: Sloan Heather , Patriat Philippe
Published: September 2004

We reconstruct the flanks of the Mid‐Atlantic Ridge (MAR) between 28° and 29°N from 1 to 10 Ma at intervals of 1 Myr for the purpose of investigating evolution of young oceanic lithosphere morphology and its variation through time using an innovative method that combines seafloor subsidence correction with interpolated isochrons and rotation poles. Reconstruction results are consistent with formation of abyssal hills every 1 to 2 Myr in 2–3 Myr old lithosphere at the outer edge of the ridge mountains as a result of transition from dynamic regime near the axis to isostatic regime of the flanks. The oblique passage of structures formed at the axial valley walls through this transition zone may play a role in the development of inside corner high bathymetry. Asymmetric juxtaposition of abyssal hill morphology in reconstruction is indicative of independent formation and evolution of the morphotectonic fabric on opposing flanks. The two major factors affecting asymmetric ridge flank morphology are found to be sense of axial offset and fluctuation of magmatic activity at the segment scale. Sense of axial offset determines the relative distribution of inside and outside corner bathymetry on the flanks. Enhanced magma supply and associated segment propagation may contribute to half‐spreading rate asymmetry, accretion of thicker crust, and formation of larger abyssal hills on the faster spreading flank. Consistent alignment in reconstruction of the base of the steep walls bounding inside corner bathymetry confirms that they mark the boundaries between segments on the flanks and that the deep sediment‐filled basins, typically identified as discordant zones, are attributable to outside corner bathymetry.
Accelerated thawing of subarctic peatland permafrost over the last 50 years
Authors: Payette Serge , Delwaide Ann , Caccianiga Marco , Beauchemin Michel
Published: September 2004

In this study we provide a quantification of the main patterns of change of a subarctic peatland caused by permafrost decay monitored between 1957 and 2003. Up‐thrusting of the peatland surface due to permafrost aggradation during the Little Ice Age resulted in the formation of an extensive peat plateau that gradually fragmented into residual palsas from the 19th century to the present. Only about 18% of the original surface occupied by permafrost was thawed in 1957, whereas only 13% was still surviving in 2003. Rapid permafrost melting over the last 50 years caused the concurrent formation of thermokarst ponds and fen‐bog vegetation with rapid peat accumulation through natural successional processes of terrestrialization. The main climatic driver for accelerated permafrost thawing was snow precipitation which increased from 1957 to present while annual and seasonal temperatures remained relatively stable until about the mid‐1990s when annual temperature rose well above the mean. Contrary to current expectations, the melting of permafrost caused by recent climate change does not transform the peatland to a carbon‐source ecosystem as rapid terrestrialization exacerbates carbon‐sink conditions and tends to balance the local carbon budget.
El Niño signal variability in the precipitation over southeastern South America during austral summer
Authors: Silvestri Gabriel E.
Published: September 2004

Some aspects of El Niño (EN) events signal in the precipitation over southeastern South America (SESA) during austral summer are examined. In February–March this signal covers most of the southeast part of SESA and has a wide range of variability in its intensity. The rainiest EN events are characterized by an intensification of the moisture flow from the amazonic forest to SESA jointly with an enhancement of the subtropical jet over South America. The dynamics in upper‐levels is associated with a circulation field in the Southern Hemisphere dominated by the presence of the ENSO pattern described in previous studies. During less rainy EN events the moisture flow towards SESA diminishes; and, the structure of the ENSO pattern of circulation over South America implicates a weakening of the subtropical jet. Therefore, the characteristics of the low and upper levels circulation modulate the intensity of the rain over SESA during these events.
Southern Hemisphere climate response to ozone changes and greenhouse gas increases
Authors: Shindell Drew T. , Schmidt Gavin A.
Published: September 2004

While most of the Earth warmed rapidly during recent decades, surface temperatures decreased significantly over most of Antarctica. This cooling is consistent with circulation changes associated with a shift in the Southern Annular Mode (SAM). It has been suggested that both Antarctic ozone depletion and increasing greenhouses gases have contributed to these trends. We show that a climate model including the stratosphere and both composition changes reproduces the vertical structure and seasonality of observed trends. We find that the two factors have had comparable surface impacts over recent decades, though ozone dominates above the middle troposphere. Projected impacts of the two factors on circulation over the next fifty years oppose one another, resulting in minimal trends. In contrast, their effects on surface climate reinforce one another, causing a departure from the SAM pattern and a turnabout in Antarctic temperatures, which rise more rapidly than elsewhere in the Southern Hemisphere.
High new production in the Bay of Bengal: Possible causes and implications
Authors: Kumar Sanjeev , Ramesh R. , Sardesai S. , Sheshshayee M. S.
Published: September 2004

We report the first measurements of new production (15N tracer technique), the component of primary production that sustains on extraneous nutrient inputs to the euphotic zone, in the Bay of Bengal. Experiments done in two different seasons consistently show high new production (averaging around 4 mmol N m−2 d−1 during post monsoon and 5.4 mmol N m−2 d−1 during pre monsoon), validating the earlier conjecture of high new production, based on pCO2 measurements, in the Bay. Averaged over annual time scales, higher new production could cause higher rate of removal of organic carbon. This could also be one of the reasons for comparable organic carbon fluxes observed in the sediment traps of the Bay of Bengal and the eastern Arabian Sea. Thus, oceanic regions like Bay of Bengal may play a more significant role in removing the excess CO2 from the atmosphere than hitherto believed.
Effect of the solar radiation in the topside atmosphere/ionosphere of Mars: Mars Global Surveyor observations
Authors: Breus T. K. , Krymskii A. M. , Crider D. H. , Ness N. F. , Hinson D. , Barashyan K. K.
Published: September 2004

The peak electron density in the ionosphere of Mars and the neutral atmosphere scale height are proportional to the solar radiation flux. The data of the radio occultation experiments on board Mariner 9 and Viking 1 and 2 have already been analyzed to derive the relationship between the peak electron density and neutral atmosphere scale height and F10.7 flux which was used as a proxy of the solar UV radiation. The data points from Mariner 9 and Viking 1 and 2 missions are distributed from −40° to +38° in latitude and rather nonuniformly distributed in longitude. The experiment with the Mars Global Surveyor (MGS) accelerometer has revealed significant diurnal variations and latitudinal and longitudinal variations in the neutral atmosphere density and scale height. The effect of the solar radiation can be more confidently established if the effects of diurnal, latitudinal, and longitudinal variations are minimized. In the northern hemisphere the 732 electron density profiles derived from the data of the MGS radio science experiment, which were collected during the mapping phase of the mission, are located in the narrow latitude interval from +63° to +77°. In the southern hemisphere, 219 profiles are located in the latitude interval from −69° to −64.5°. These profiles were also obtained within narrow intervals of local time and are practically uniformly distributed in longitude. The peak electron density and the effective scale height of the neutral atmosphere density in the vicinity of the ionization peak have been derived for each of the profiles studied. The daily averages of E10.7 index are derived from the solar radiation fluxes measured near Earth. Their values are then recalculated, accounting for the relative positions of Mars and the Earth, and are used as a proxy of the EUV radiation flux at Mars. For the time period November 2000 to January 2001 the calculated daily averages of the adjusted peak electron density and effective scale height have been compared with the daily averages of E10.7 index. Analysis has shown that Te was, on average, slightly larger in the southern hemisphere than it was in the northern hemisphere. The hot electrons could be actually trapped within the latitude interval from −69° to −64.5° and the strong crustal magnetic fields have detectable but modest effect in the southern hemisphere Te might be, on average, 50–60% larger than Te in the northern hemisphere. In the case of density profiles measured in the period 1–31 January 2001 in the northern hemisphere Te is likely primarily controlled by the solar wind interaction with the Martian atmosphere/ionosphere.
Coseismic stress changes and crustal deformation on the Reykjanes Peninsula due to triggered earthquakes on 17 June 2000
Authors: Árnadóttir Thóra , Geirsson Halldór , Einarsson Páll
Published: September 2004

A large (Mw = 6.5) earthquake struck the South Iceland Seismic Zone (SISZ) on 17 June 2000. The 17 June main shock triggered increased seismicity over a large area and significant slip on at least three distinct faults on the Reykjanes Peninsula, up to 87 km to the west of the event. A second large (Mw = 6.4) earthquake in the SISZ occurred on 21 June 2000, about 17 km west of the 17 June main shock. This event does not appear to have triggered as much activity on the Reykjanes Peninsula as the 17 June main shock, although the epicenter was closer. Crustal deformation signals due to the June 2000 earthquakes on the Reykjanes Peninsula were observed with campaign and continuous GPS and synthetic aperture radar interferometry, with the largest coseismic deformation signal near lake Kleifarvatn. We model the faults using three uniform slip rectangular dislocations in an elastic half‐space. Best fit uniform slip models consistent with seismic and geodetic data indicate that all three faults trend N‐S and the motion on them was primarily right‐lateral strike slip. Our study suggests that the event near Kleifarvatn had a significantly larger moment than seismic estimates, indicating a component of aseismic slip on the fault lasting no more than several hours. Static Coulomb failure stress change calculations indicate that the event at Kleifarvatn increased the Coulomb stress at the hypocenter of the Núpshlídarháls event by 0.1–0.2 MPa as well as loading the Hvalhnúkur fault.
Characterization of a spiral‐shaped time domain reflectometry probe
Authors: Bittelli Marco , Flury Markus , Campbell Gaylon S. , Schulz Volker
Published: September 2004

Time domain reflectometry is one of the most common methods to determine water content in porous media. Transmission lines used to carry the electromagnetic pulse can take many different forms and shapes and can be tailored to specific needs. Here we describe the design and characterization of a miniaturized transmission line, specifically designed for applications in laboratory settings. The sensor consists of a spiral‐shaped Cu waveguide, which is constructed by etching techniques used in printed circuit board manufacturing. The waveguides are 0.508 mm wide and have a separation of 0.508 mm. The overall diameter of the spiral is 42 mm, and the overall length of the waveguide is 38 cm. The probe was tested experimentally in media of different dielectric properties using a Tektronix cable tester. The electrostatic field distribution of the probe was simulated using a two‐dimensional numerical solution of the Laplace equation. The numerical analysis was used to compute a weighting function of the measurement and to determine the equivalent dielectric permittivity. For the range of permittivities expected in environmental porous media, such as soils and sediments, the sampling area of the probe was not affected by the water content of the medium.
Epigenome changes in active and inactive Polycomb‐group‐controlled regions
Authors: Breiling Achim , O'Neill Laura P , D'Eliseo Donatella , Turner Bryan M , Orlando Valerio
Published: September 2004

The Polycomb group (PcG) of proteins conveys epigenetic inheritance of repressed transcriptional states. InDrosophila, the Polycomb repressive complex 1 (PRC1) maintains the silent state by inhibiting the transcription machinery and chromatin remodelling at core promoters. Using immunoprecipitation ofin vivoformaldehyde‐fixed chromatin in phenotypically diverse cultured cell lines, we have mapped PRC1 components, the histone methyl transferase (HMT) Enhancer of zeste (E(z)) and histone H3 modifications in active and inactive PcG‐controlled regions. We show that PRC1 components are present in both cases, but at different levels. In particular, active target promoters are nearly devoid of E(z) and Polycomb. Moreover, repressed regions are trimethylated at lysines 9 and 27, suggesting that these histone modifications represent a mark for inactive PcG‐controlled regions. These PcG‐specific repressive marks are maintained by the action of the E(z) HMT, an enzyme that has an important role not only in establishing but also in maintaining PcG repression.
Pulmonary surfactant protein A isolation as a by‐product of porcine pulmonary surfactant production
Authors: Kubrusly Flávia Saldanha , Iourtov Dmitri , Leme Ednilse , Raw Isaias
Published: September 2004

A pulmonary surfactant reduces surface tension at the air/liquid interface of the alveoli and stabilizes alveoli at low lung volumes. Surfactant deficiency and dysfunction were shown to be present in a number of pulmonary diseases, and surfactant replacement therapy is the common clinical conduct. The hydrophilic SP‐A (surfactant protein A) is absent when solvent extraction was used during exogenous surfactant production. Addition of SP‐A to the surfactant preparation increases the surface activity and completely counteracts inhibition by blood proteins. SP‐A recognizes and binds to carbohydrate structures on the surfaces of pathogenic micro‐organisms, and acts as opsonins or cross‐linking molecules by binding to a variety of cells that participate in the pulmonary immune response. The purification procedure yielded 206 mg of high‐purity SP‐A/kg of porcine lung, as judged by gel filtration, SDS/PAGE and Western blotting. The electrophoretic profiles obtained showed that pure SP‐A consists of proteins of wide molecular mass in the range 26–36 kDa and a dimer in the range 56–60 kDa. The Western‐blot results displayed the same band pattern profile after incubating the membrane using a commercially available polyclonal anti‐SP‐A antibody produced in goat. Gel‐filtration experiments confirmed the molecular mass of SP‐A in 10 mM NaCl solution. The isolated SP‐A showed mannose‐binding ability, representative of its functionality.
Immobilization of Aspergillus niger tannase by microencapsulation and its kinetic characteristics
Authors: Yu Xiaowei , Li Yongquan , Wang Chunxia , Wu Dan
Published: September 2004

Tannase from Aspergillus niger was microcapsulated with a coacervate calcium alginate membrane surrounding a liquid core. The activity yield was 36.8% under the optimum conditions of immobilization, namely 6 g/litre sodium alginate and 0.18 M CaCl2. The optimum pH and temperature for free and immobilized tannase were 5.0 and 30 °C, and 6.0 and 40 °C, respectively. The pH stability, as well as thermal stability, was improved significantly after microencapsulation. Km values for the free and immobilized enzyme were 0.011 and 0.041 μM respectively. Vmax values changed from 416 to 131 μmol·min−1·mg−1 upon immobilization. The kinetic parameters for free and immobilized tannase were also determined. The immobilized tannase was stable enough to be used for up to 15 runs. These kinetic characteristics of the immobilized tannase show more promise for industrial application than those of the free enzyme.
A simple method for the production of recombinant proteins from mammalian cells
Authors: Wu Chia‐Hung , Balasubramanian Wesley Roy , Ko Ya‐Ping , Hsu George , Chang Shih‐En , Prijovich Zeljko M. , Chen Kai‐Chuan , Roffler Steve R.
Published: September 2004

Expression of recombinant proteins in mammalian cells is useful for obtaining products with normal post‐translational modifications. We describe a simple and economical method for the production of milligram levels of proteins in murine fibroblasts. Retroviral or lipofectAMINE™ (Gibco Laboratories) transduction was employed to generate stable murine‐fibroblast producer cells. Confluent cultures of stable fibroblast clones were maintained for up to 1 month in 0.5% serum. Culture medium was collected every 2–3 days and polyhistidine‐tagged proteins were purified by ammonium sulphate precipitation and Ni2+‐nitrilotriacetic acid affinity chromatography. Highly pure, active, glycosylated recombinant proteins, including human β‐glucuronidase, mouse β‐glucuronidase, aminopeptidase N (CD13) and a single‐chain antibody–enzyme fusion protein, were obtained with yields of 3–6 mg/l of culture medium. Fc‐tagged proteins were also produced and purified in a single step by Protein A affinity chromatography with yields of 6–12 mg/l. The techniques described here allow simple and economical production of recombinant mammalian proteins with post‐translational modifications.
Modelling the electrodialytic recovery of sodium lactate
Authors: Fidaleo Marcello , Moresi Mauro
Published: September 2004

The recovery of sodium lactate from model solutions by ED (electrodialysis) was studied using a sequential experimental procedure so as to assess the main engineering parameters (i.e. ion transport numbers in solution and electro‐membranes, effective solute and water transport numbers, effective membrane surface area, surface resistances and limiting current intensity) affecting ED stack design and/or optimization. Of the major factors that determine the performance of this ED process, Ω (the current efficiency) was about 88% in the constant‐current region, while ε (the specific energy consumption) increased from 0.14 to 0.31 kWh·kg−1 for a solute recovery yield of 95% and j (current density) increasing from 112 to 337 A·m−2. The specific‐resistance values of the anion‐ or cation‐exchange membranes were found to be five or two times greater respectively than those extracted from literature and measured in aqueous NaCl solutions.
Characterization and properties of acid phosphatases with phytase activity produced by Aspergillus caespitosus
Authors: Guimarães Luis Henrique S. , Terenzi Héctor F. , Jorge João A. , Leone Francisco A. , Polizeli Maria de Lourdes T. M.
Published: September 2004

High levels of thermostable acid phosphatases were produced by Aspergillus caespitosus in culture media supplemented with xylan birchwood or agricultural residues, as carbon sources. The optimal culture conditions for production of phosphatases were 40 °C and pH 6.0. Extra‐ and intra‐cellular acid phosphatases were purified by chromatography on DEAE‐cellulose, followed by concanavalin A–Sepharose affinity separation. Both extra‐ and intra‐cellular enzymes were glycoproteins showing 63.0 and 58.3% of carbohydrate content respectively. Molecular masses estimated on Sepharose CL‐6B column were 186 and 190±15 kDa, and 84 and 74±5 kDa according to SDS/PAGE, for extra‐ and intra‐cellular acid phosphatases respectively. Taken together, these results suggest that both native enzymes were homodimers. Optimum temperature and pH for both phosphatase activities were 80 °C and 5.5 respectively. The extra‐ and intra‐cellular acid phosphatases were stable for more than 60 min at 60 °C. The extracellular acid phosphatase was slightly inhibited by NaF, in contrast with the significant inhibition of the intracellular form. KH2PO4 inhibited both activities equally. Both extra‐ and intracellular acid phosphatases were tartarate‐resistant. Among several phosphorylated substrates used, the extracellular enzyme preferentially hydrolysed p‐nitrophenyl phosphate. Kinetic parameters calculated for the hydrolysis of p‐nitrophenyl phosphate by extracellular acid phosphatase were h (Hill coefficient)=1.2, K0.5=0.082 mM and Vmax=4.43 units/mg, whereas the intracellular enzyme exhibited Michaelian kinetics with Km=0.029 mM and Vmax=0.082 unit/mg. Phytase activity was also observed for both the enzymes, suggesting that they could be useful for biotechnological applications.