bluuebunny/crossref_metadata_2025 huggingface dataset:
Carbon film growth on iron substrates by a CVD method
Authors: Ding Yun‐Shuang , Li Wei‐Na , Shen Xiong‐Fei , Galasso Francis S. , Suib Steven L. , DiCarlo Joe
Published: January 2005

Carbon film coatings have been produced by a hot‐wall chemical vapor deposition (CVD) method under moderate conditions from pyrolysis of a mixture of propane and argon on an Fe(110) substrate at temperatures of 800–900 °C for different deposition times. The effects of temperature and reaction time on the growth of the carbon films were studied. Field‐emission scanning electron microscopy (FESEM), Raman microscopy, Auger electron spectroscopy (AES) and x‐ray diffraction methods have been performed to study the surface morphologies, growth features and microstructures of the carbon film coatings. The FESEM analyses indicated that carbon films on an Fe substrate consisted of flat‐layer and filamentous morphologies. Raman and AES analyses showed that the carbon initially was crystalline but the degree of disorder in the top layer of the carbon film increased with increasing deposition temperature. High‐resolution transmission electron microscopy studies are also in agreement with Raman results. The same trend was observed when the deposition time was increased from 5 to 30 min. Copyright © 2005 John Wiley & Sons, Ltd.
Segregation in zirconia: equilibrium versus non‐equilibrium segregation
Authors: Nowotny J. , Sorrell C. C. , Bak T.
Published: January 2005

The present work considers the differences between the following two phenomena: equilibrium segregation, which is a thermodynamic phenomenon where the driving force is excess interfacial energy; and non‐equilibrium segregation, which can be produced by phenomenological shocks applied to the solid surface. Fully stabilized cubic yttria‐stabilized zirconia (YSZ) is used as the exemplar for these considerations. Equilibrium segregation in YSZ results in enrichment of the surface and near‐surface layers in constituent elements, typically yttria and impurities. This segregation is an intrinsic material property and has an impact on the performance of zirconia at elevated temperatures. On the other hand, non‐equilibrium segregation leads to a complex distribution of properties (structure and concentration gradients) that are determined by the experimental procedures used rather than being a material property. However, such non‐equilibrium segregation can result in localized structural changes. The present paper also considers the effect of the gas phase on surface properties of metal oxides, including YSZ, and the surface dynamics of YSZ at temperatures below that required to reach equilibrium. Copyright © 2005 John Wiley & Sons, Ltd.
A comparison of the Dorfman–Berbaum–Metz and Obuchowski–Rockette methods for receiver operating characteristic (ROC) data
Authors: Hillis Stephen L. , Obuchowski Nancy A. , Schartz Kevin M. , Berbaum Kevin S.
Published: January 2005

There are several different statistical methods for analysing multireader ROC studies, with the Dorfman–Berbaum–Metz (DBM) method being the most frequently used. Another method is the correctedFmethod proposed by Obuchowski and Rockette (OR). The DBM and OR procedures at first appear quite different: DBM is a three‐way ANOVA analysis of pseudovalues while OR is a two‐way ANOVA analysis of accuracy estimates with correlated errors. We show that the original DBM and ORFstatistics for testing the null hypothesis of equal treatments have the same form and will typically have similar values; however, differences in the denominator degrees of freedom will result in differences inp‐values even when theFstatistics are identical. We show how the methods can be generalized to include variations in the accuracy measure, covariance method, and degrees of freedom. Identical results are obtained when the methods agree with respect to all three of these procedure parameters; hence for a particular choice of procedure parameters the choice of method appears to depend mainly on software preference and availability. The methods are compared using data from a factorial study with two modalities, five readers, and 114 patients. Copyright © 2005 John Wiley & Sons, Ltd.
Enacting reform‐based science materials: The range of teacher enactments in reform classrooms
Authors: Schneider Rebecca M. , Krajcik Joseph , Blumenfeld Phyllis
Published: January 2005

To promote large‐scale science education reform, developers must create innovations that teachers can use to learn and enact new practices. As part of an urban systemic reform effort, science materials were designed to reflect desired reforms and to support teacher thinking by addressing necessary content, pedagogy, and pedagogical content knowledge for teachers. The goal of this research was to describe teachers' enactments in comparison to reform as instantiated in the materials. Four middle school teachers' initial enactment of an inquiry‐based science unit on force and motion were analyzed. Findings indicate two teachers' enactments were consistent with intentions and two teachers' enactments were not. However, enactment ratings for the first two were less reflective of curriculum intent when challenges were greatest, such as when teachers attempted to present challenging science ideas, respond to students' ideas, structure investigations, guide small‐group discussions, or make adaptations. Overall, findings suggest that purposefully using materials with detailed lesson descriptions and specific, consistent supports for teacher thinking can help teachers with enactment. However, materials alone are not sufficient; reform efforts must include professional development and efforts to create systemic change in context and policy to support teacher learning and classroom enactment. © 2005 Wiley Periodicals, Inc. J Res Sci Teach 42: 283–312, 2005
Endosonography of the anal sphincter in women of different ages and parity
Authors: Starck M. , Bohe M. , Fortling B. , Valentin L.
Published: January 2005

Objectives

To obtain reference data representative of normal findings at anal endosonography in pregnant and non‐pregnant women. To determine intraobserver and interobserver agreement in the detection of endosonographic anal sphincter defects in asymptomatic women.

Methods

Twenty‐five non‐pregnant nulliparous women and 25 non‐pregnant parous women (age range, 20–67 years) and 47 pregnant women (age range, 21–39 years) underwent anal manometry and anal endosonography. The endosonographic internal and external sphincter thickness and sphincter length were measured online. Endosonographic sphincter defects were measured and classified offline from videotapes by two independent examiners using an endosonographic defect score ranging from 0 (no defect) to 16 (maximal defect), the score taking into account the location and the longitudinal and circumferential extension of the defect.

Results

Endosonographic sphincter thickness and length did not differ between non‐pregnant nulliparous and parous women and did not change substantially with age. The anal sphincter was thicker and the anal resting pressure area and manometric sphincter length were greater in pregnant than in non‐pregnant women of the same age (20–39 years). There was good intra‐ and interobserver agreement with regard to detection of endosonographic anal sphincter defects (kappa ≥ 0.70). Eighteen (19%) women had endosonographic sphincter defects but in only four (4%; 4/97) cases were they moderate or large (defect score, 7–10). Ten (20%) of the non‐pregnant women reported minor gas incontinence and one reported minor incontinence for both gas and liquid stool. The frequency of incontinence did not differ between women with and without sphincter defects.

Conclusions

Reference data representative of normal findings at anal endosonography have been established for non‐pregnant women and for nulliparous women in the third trimester of pregnancy. Small endosonographic sphincter defects and minor gas incontinence are common in women without known sphincter trauma. They seem to be unrelated to each other and may be regarded as normal variants. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.
First‐trimester diagnosis of imperforate anus
Authors: Taipale P. , Rovamo L. , Hiilesmaa V.
Published: January 2005

Imperforate anus or anorectal atresia is often associated with major fetal structural defects but it may also be an isolated abnormality. Prenatal diagnosis is difficult but may be assisted by ultrasound detection of a dilated distal bowel or rectum. We report on a fetus at 12 weeks of gestation in which a dilated colon was detected at ultrasound examination. Dilatation of the colon was clearly seen in the first and third trimesters of pregnancy, but was difficult to detect in the second trimester. At birth, the newborn was diagnosed with a low type of imperforate anus. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.
The Decapod Crustacean Circulatory System: A Case That Is neither Open nor Closed
Authors: McGaw Iain J.
Published: January 2005

Historically, the decapod crustacean circulatory system has been classed as open. However, recent work on the blue crab,Callinectes sapidus, suggests the circulatory system may be more complex than previously described. Corrosion casting techniques were refined and used to map the circulatory system of a variety of crab species (order: Decapoda; family: Cancridae) to determine if the complexity observed in the blue crab was present in other species. Seven arteries arose from the single chambered heart. The anterior aorta, the paired anterolateral arteries, and the paired hepatic arteries exited from the anterior aspect of the heart. The small-diameter posterior aorta exited posteriorly from the heart. Exiting from the ventral surface of the heart, the sternal artery branched to supply the legs and mouthparts of the crab. These arteries were more complex than previously described, with arterioles perfusing all areas of the body. The arterioles split into fine capillary-like vessels. Most of these capillaries were blind ending. However, in several areas (antennal gland, supraesophageal ganglion) complete capillary beds were present. After passing through the capillary-like vessels, blood drained into a series of sinuses. However, rather than being arbitrary spaces as previously described, scanning electron micrographs showed the sinuses to be distinct units. Most of the sinuses formed a series of flattened membrane-bound lacunae. This complexity may qualify the decapod crustacean circulatory system as one that is “partially closed” rather than open.
Use of an Automated Image Processing Program to Quantify Recombinant Adenovirus Particles
Authors: Obenauer-Kutner Linda J. , Halperin Rebecca , Ihnat Peter M. , Tully Christopher P. , Bordens Ronald W. , Grace Michael J.
Published: January 2005

Electron microscopy has a pivotal role as an analytical tool in pharmaceutical research. However, digital image data have proven to be too large for efficient quantitative analysis. We describe here the development and application of an automated image processing (AIP) program that rapidly quantifies shape measurements of recombinant adenovirus (rAd) obtained from digitized field emission scanning electron microscope (FESEM) images. The program was written using the macro-recording features within Image-Pro® Plus software. The macro program, which is linked to a Microsoft Excel spreadsheet, consists of a series of subroutines designed to automatically measure rAd vector objects from the FESEM images. The application and utility of this macro program has enabled us to rapidly and efficiently analyze very large data sets of rAd samples while minimizing operator time.
Improved Background Removal Method Using Principal Components
Analysis for Spatially Resolved Electron Energy Loss Spectroscopy
Authors: Borglund Niclas , Åstrand Per-Gustav , Csillag Stefan
Published: January 2005

Principal components analysis (PCA) factor filtering is implemented
for the improvement of background removal in noisy spectra. When PCA is
used as a method for filtering before background removal in electron
energy loss spectroscopy elemental maps, an improvement in the accuracy
of the background fit with very short fitting intervals is achieved,
leading to improved quality of elemental maps from noisy spectra. This
opens the possibility to use shorter exposure times for elemental
mapping, leading to fewer problems with, for example, drift and beam
damage.
Low-Energy STEM of Multilayers and Dopant Profiles
Authors: Merli P.G. , Morandi V.
Published: January 2005

A conventional scanning electron microscope equipped with a
LaB6 source has been modified to operate in a scanning
transmission mode. Two detection strategies have been considered, one
based on the direct collection of transmitted electrons, the other on
the collection of secondary electrons resulting from the conversion of
the transmitted ones. Two types of specimens have been mainly
investigated: semiconductor multilayers and dopant profiles in
As-implanted Si. The results show that the contrast obeys the rules of
mass–thickness contrast whereas the resolution is always defined
by the probe size independently of specimen thickness and beam
broadening. The detection strategy may affect the bright field (light
regions look brighter) or dark field (heavy regions look brighter)
appearance of the image. Using a direct collection of the transmitted
electrons, the contrast can be deduced from the angular distribution of
transmitted electrons and their collection angles. When collecting the
secondary electrons to explain the image contrast, it is also necessary
to take into account the secondary yield dependence on the incidence
angle of the transmitted electrons.
Cytochemical Differences in Bacterial Glycocalyx
Authors: Krautgartner Wolf Dietrich , Vitkov Ljubomir , Hannig Matthias , Pelz Klaus , Stoiber Walter
Published: January 2005

To examine new cytochemical aspects of the bacterial adhesion, a strain 41452/01 of the oral commensalStreptococcus sanguisand a wild strain ofStaphylococcus aureuswere grown with and without sucrose supplementation for 6 days. Osmiumtetraoxyde (OsO4), uranyl acetate (UA), ruthenium red (RR), cupromeronic blue (CB) staining with critical electrolytic concentrations (CECs), and the tannic acid–metal salt technique (TAMST) were applied for electron microscopy. Cytochemically, only RR-positive fimbriae inS. sanguiswere visualized. By contrast, some types of fimbriae staining were observed inS. aureusglycocalyx: RR-positive, OsO4-positive, tannophilic and CB-positive with ceasing point at 0.3 M MgCl2. The CB staining with CEC, used for the first time for visualization of glycoproteins of bacterial glycocalyx, also reveals intacellular CB-positive substances—probably the monomeric molecules, that is, subunits forming the fimbriae via extracellular assembly. Thus, glycosylated components of the biofilm matrix can be reliably related to single cells. The visualization of intracellular components by CB with CEC enables clear distinction betweenS. aureusand other bacteria, which do not produce CB-positive substances. The small quantities of tannophilic substances found inS. aureusmakes the use of TAMST for the same purpose difficult. The present work protocol enables, for the first time, a partial cytochemical differentiation of the bacterial glycocalyx.
Errors, Artifacts, and Improvements in EBSD Processing and Mapping
Authors: Tao Xiaodong , Eades Alwyn
Published: January 2005

Electron back scatter diffraction (EBSD) mapping and indexing has rapidly come into widespread use. However, inadequate attention has been paid to the details of the method. Many of the algorithms in current use were chosen because they were the first ones that were found to work, rather than because they were optimum. Results of systematic study are presented. It is shown that more than one method can successfully correct a sampling artifact, that there is an optimum binning ratio, that Gaussian filtering provides an alternative to “butterfly convolution,” that better alternatives for mapping image quality than those in current use are available, and that saving all the original patterns is practical and advantageous.
The Transillumination Possibility of Imidazole–Osmium
Postfixed Tissue and Its Consequences for the Handling of Tissue
Samples
Authors: Voigt Tilman , Dauber Wolfgang
Published: January 2005

Osmium postfixation is established as a routine procedure for
transmission electron microscopy (TEM). On the one hand, this routine
procedure leads to good results for TEM, but on the other hand results
in blackened tissue samples that do not allow examination of any
structures within the embedded tissue sample by a light microscope.
Equivalent fixation results for TEM are achieved with
imidazole–osmium postfixation, and with this postfixation method
tissue is not blackened and can be transilluminated with point light
sources. This allows easier recognition of histological details within
tissue samples and makes it possible to screen embedded samples for
appropriate ultrastructural processing. Jejunum is used to demonstrate
the method.
Editorial
Authors: Lyman Charles E.
Published: January 2005

With this issue, Microscopy and Microanalysis begins its
eleventh year of publication. Our journal is getting better
year-by-year. In 2004 this journal published more scientific articles
than in any previous year. The first biological special issue, on
parasites, increased the prominence of the life sciences within these
pages. The growing popularity of the journal is also indicated by
several letters to the editor about matters arising in certain
articles. Such scientific exchanges highlight for our readership the
subtleties of interpretation regarding advances in science,
instrumentation, technique, and theory.
How was it for you? Men, prostate cancer and radiotherapy
Authors: Owens J. , Kelsey S. , White A.
Published: January 2005

This paper explores the views of men who have experienced external beam radiotherapy as part of their treatment for prostate cancer. Using three focus groups, the study aimed to explore men's experience of radiotherapy. However it soon became clear that it is not possible to disentangle the experience of radiotherapy from that of the whole cancer journey. Four themes emerged from qualitative analysis of the data, namely, making decisions (feeling prepared and informed), the experience of radiotherapy, side effects of treatment and sources of support.

The findings indicate that health care professionals involved in radiotherapy treatment delivery need to understand and maintain sensitivity to the physical and emotional impact of the men's experience prior to radiotherapy in addition to those experienced during radiotherapy. In order to raise awareness and understanding of whole experience from the men's perspective, it is suggested that feedback of patient experience should become an integral part of radiotherapy department activity.

This paper is an extract from a wider study that explores the experience of men undergoing brachytherapy and external beam radiotherapy.
Provision of IMRT in the UK. Part 2: Current levels, planned expansion and obstacles to implementation
Authors: Baker C.R. , Hardy V.
Published: January 2005

UK Radiotherapy Departments have been surveyed to establish the current level of provision of intensity-modulated radiotherapy (IMRT) and its expected growth in the next 2 to 5 years. At the time of writing, nine UK Departments have implemented IMRT, providing a national capacity of approximately 20 new patients per month. By 2005, a further nine Departments expect to have implemented IMRT. As confidence and experience of IMRT grows, streamlining of quality control (QC) and the development of class solutions for inverse treatment planning are expected to significantly reduce the preparation time required for each patient and so increase patient capacity in all Departments.

Staff training requirements, extra workloads in treatment planning and QC, identification of inverse planning parameters and current limitations of inverse treatment planning systems were identified as the key learning points for Departments that have been through the implementation process. Obstacles identified as preventing early implementation include equipment availability, staff shortages and heavy clinical workloads limiting the amount of time available for implementation.
Systematic in vivo dosimetry for quality assurance using diodes. Part 1: Experiences and results of the implementation of entrance dose measurements
Authors: Appleyard R. , Ball K. , Hughes F.E. , Kilby W. , Lassen S. , Nicholls R. , Rabett V. , Sage J. , Smith M. , Thomson E.
Published: January 2005

Purpose: This paper describes our experiences of implementing systematic in vivo dosimetry at the Norfolk and Norwich Hospital and reviews the results of 2,254 entrance dose measurements made over a 17-month period.

Methods and materials: Entrance dose measurements using p-type diodes were performed on all new planned patients. The calibration procedure and correction factors applied are described. A 4% tolerance was applied.

Results: The results of all measurements indicated a small mean deviation from expected entrance dose of 10.77% and a standard deviation of 2.85%. 16.7% of all measurements exceeded the 4% tolerance with 9.2% exceeding a 5% level. The estimated overall errors for 578 treatments were calculated using the weighted averages of all beams. A narrower SD of 1.96% combined with only 4.8% of all treatments exceeding a 4% tolerance show that large deviations from a single field do not always translate into significant overall errors.

Conclusions: Global dosimetric accuracy was within clinically acceptable limits and variations between measured and expected doses were mainly attributable to factors affecting diode reading. A number of errors in calculating deviations and the inconsistent application of the protocol suggest the need for interfacing the diode system with software control.
Pilot study investigating efficacy of acupressure wristbands for reduction of radiotherapy-induced nausea
Authors: Bridge, P. , Chakraborti P.R. , Thomas G. , Filkins L. , Fleet A.J.
Published: January 2005

Persistent nausea remains one of the most distressing side effects of radiotherapy treatment despite advances in anti-emetic medication.

Stimulation of the Nei-Guan (P6) acupoint on the wrist has been used in Chinese medicine to treat nausea for over 4,500 years. Studies have demonstrated that acupressure wristbands can reduce postoperative nausea, motion sickness, morning sickness and chemotherapy-induced nausea. This pilot study aimed to determine if they could also help reduce radiotherapy-induced nausea. There are no published reports of their use in this setting, thus this preliminary pilot was conducted before engaging in a major study.

A prospective, paired, cross-over study investigated the impact adding acupressure wristbands to the usual anti-emetic care had on radiotherapy-induced nausea. Over the trial period, 30 patients were recruited when they reported radiotherapy-induced nausea to radiotherapists. Their daily nausea levels were assessed for a fortnight using a simple questionnaire and an anti-emetic tablet count. Comparing the 2 weeks data for these patients showed that there was a dramatic drop in their scores when the acupressure wristbands were used. There was a mean score drop of 61% for the combined nausea and vomiting frequency and severity, i.e. a 61% improvement in quality of life.

This study suggested that acupressure wristbands might have a role to play in the treatment of radiotherapy-induced nausea. It is recommended that further studies be conducted to determine their exact role. They potentially offer several benefits when compared to anti-emetic medication. They are easy to use, have no side effects and are more economical since they are reusable. Furthermore, acupressure wristbands place the patient in control of their nausea to some degree. This in turn will make the patients feel less anxious, less depressed and reduce the common feelings of helplessness that often accompanies cancer patients.
Towards conformal radiotherapy: an audit of technique accuracy
Authors: Stanley S.
Published: January 2005

Introduction: Conformal radiotherapy demands an accurate and reproducible treatment set up technique therefore the purpose of this study was to determine whether the current techniques were suitable for use with conformal treatment plans and to establish whether the current verification procedure was adequate.

Method: 30 patients undergoing radical radiotherapy were recruited to each technique to be studied. Megavoltage images (MVI's) were taken twice during week one and then at weekly intervals. All study images were assessed after the patient had completed the treatment course using Masthead PIPS software. Field placement errors were recorded in x, y and z directions where appropriate. Patient characteristics were recorded to establish whether there was any relationship between reproducibility and patient size.

Results: Head and neck: 26.6% patients had one or more errors >5 mm, 3.3% had consistent errors >5 mm throughout treatment. Poor fit of the beam direction shell was associated with errors >5 mm. Chest and abdomen: The technique was modified after 20 patients due to the large number of errors exceeding 10 mm. A significant (p < 0.01) reduction in the number of errors was in the modified technique group, this group also had a significantly (p < 0.01) reduced range of errors in the y direction. Pelvis: Significantly more errors were seen in the y and z directions using the sinmed kneeblock. A link between field placement errors and patient size was found.

Conclusion: Imaging on the first fraction is not sufficient to determine whether a set up error is likely to occur consistently during treatment, at least two sets of images are required. The study has shown that technique development is necessary for the chest, abdomen and pelvis prior to the introduction of conformal radiotherapy.
Continuous geomagnetic field models for the past 7 millennia: 1. A new global data compilation
Authors: Korte M. , Genevey A. , Constable C. G. , Frank U. , Schnepp E.
Published: January 2005

A global data set of archeomagnetic and paleomagnetic data covering the past 7000 years has been compiled. It consists of 16,085 results of inclination, 13,080 of declination, and 3188 of intensity for the time span 5000 BC to 1950 AD. Declination and inclination data come partly from existing databases and partly from original literature. A new global compilation of intensity data for the millennial scale is included. Data and dating uncertainties are discussed as we attempted to obtain an internally coherent data set. The global distribution of the data is very inhomogeneous in both time and space. All the data are compared to predictions from the previous 3000 year global model, CALS3K.1. This collection of data will be useful for global secular variation studies and geomagnetic field modeling, although southern hemisphere data are still underrepresented. In particular, we will use it in a further study to update and extend the existing global model, CALS3K.1. The huge increase in data compared to the previous compilation will result in significant changes from current models. As we might have missed some suitable data, we encourage the reader to notify us about any data that have not been included yet and might fit in, as improving our global millennial scale models remains our aim for the future. The data files described in this paper are available from the EarthRef Digital Archive (ERDA) at http://earthref.org/cgi‐bin/erda.cgi?n=331.
The ice age methane budget
Authors: Valdes Paul J. , Beerling David J. , Johnson Colin E.
Published: January 2005

Accounting for the natural 40% reduction in methane during the Last Glacial Maximum (LGM) represents one of the most challenging problems posed by polar ice core studies. Inverse modelling, constrained by observations, suggest it is driven by a decline in wetland sources, but this is not supported by forward modelling. Using a comprehensive Earth system model, we show that closure of the methane budget requires reduced emissions and an amplified sink caused by reduction in emissions of volatile organic compounds (VOCs) from LGM forests. Our study emphasizes a key role for the terrestrial biosphere in the methane budget during the Quaternary.
Possible satellite perspective effects on the reported correlations between solar activity and clouds
Authors: Pallé E.
Published: January 2005

Recently some correlations between low cloud cover and solar activity have been reported in the literature. In this paper we show how the flux of GCR is found to correlate positively with the low clouds and negatively with higher clouds, supporting previous theoretical predictions linking atmospheric ionization by cosmic rays and cloud cover at different altitudes. All these correlations are however only marginally significant and the only strongly significant (negative) correlation is found between low and higher cloud layers. Thus, there is strong evidence that the solar‐like variability in low cloud may be artificially induced by the satellite observing perspective.
The dynamic range of poleward energy transport in an atmospheric general circulation model
Authors: Caballero Rodrigo , Langen Peter L.
Published: January 2005

Understanding the reasons for which current climate models fail to reproduce the low equator‐to‐pole temperature gradient of past warm periods is among the major challenges in climate science. We focus here on the role of atmospheric poleward heat transport. We use an aquaplanet general circulation model (GCM) to construct a regime diagram of this quantity as a function of surface temperature and its meridional gradient, encompassing the range experienced by Earth over the Cenozoic. We find that poleward heat transport increases with surface temperature over much of this range, but saturates in the low‐gradient, high‐temperature regime where it is most needed. We identify some specific dynamical feedbacks responsible for this behavior: increasing tropospheric static stability and poleward migration of the storm tracks as global‐mean temperature increases.
China's changing landscape during the 1990s: Large‐scale land transformations estimated with satellite data
Authors: Liu Jiyuan , Tian Hanqin , Liu Mingliang , Zhuang Dafang , Melillo Jerry M. , Zhang Zengxiang
Published: January 2005

Land‐cover changes in China are being powered by demand for food for its growing population and by the nation's transition from a largely rural society to one in which more than half of its people are expected to live in cities within two decades. Here we use an analysis of remotely sensed data gathered between 1990 and 2000, to map the magnitude and pattern of changes such as the conversion of grasslands and forests to croplands and the loss of croplands to urban expansion. With high‐resolution (30 m) imagery from Landsat TM for the entire country, we show that between 1990 and 2000 the cropland area increased by 2.99 million hectares and urban areas increased by 0.82 million hectares. In northern China, large areas of woodlands, grasslands and wetlands were converted to croplands, while in southern China large areas of croplands were converted to urban areas. The land‐cover products presented here give the Chinese government and international community, for the first time, an unambiguous understanding of the degree to which the nation's landscape is being altered. Documentation of these changes in a reliable and spatially explicit way forms the foundation for management of China's environment over the coming decades.
The effect of Atlantic sea surface temperature dipole mode on hurricanes: Implications for the 2004 Atlantic hurricane season
Authors: Xie Lian , Yan Tingzhuang , Pietrafesa Leonard
Published: January 2005

Results from this study indicate that the dipole mode of tropical Atlantic Ocean sea surface temperature (SST) anomalies is correlated with the overall activity of hurricanes as well as with the annual hurricane landfall frequency along the southeast coast of the United States. The tropical Atlantic SST dipole mode could affect hurricanes in at least three ways: 1) modulating the weather in West Saharan Africa; 2) influencing the local SST and hence the atmosphere‐ocean environment in the hurricane main development region; 3) coupling with the tropical and subtropical atmospheric circulation that controls the steering of hurricanes. The warm tropical North Atlantic and cool tropical South Atlantic waters are likely one of the main causes for Florida's hurricane havoc in 2004.
Intraseasonal variability in the upper layer currents observed in the eastern equatorial Indian Ocean
Authors: Masumoto Yukio , Hase Hideaki , Kuroda Yoshifumi , Matsuura Hiroshi , Takeuchi Kensuke
Published: January 2005

Direct observations of the upper ocean velocity in the eastern equatorial Indian Ocean by an acoustic Doppler current profiler, from November 2000 to October 2001 on the equator at 90°E, demonstrate that the dominant periods of variability in the upper layer zonal and meridional currents are in intraseasonal frequency bands with periods of 30 to 50 days and 10 to 20 days, respectively. The strong intraseasonal variability in the zonal current obscures the semiannual Wyrtki jets, which can be seen clearly in the monthly averaged field. In addition, a zone of strong vertical shear of the zonal current and a distinct Equatorial Undercurrent with semiannual period are observed. The results provide us with a new perspective on importance of the energetic intraseasonal variability in the eastern equatorial Indian Ocean, which indicates strong correlation with the wind variability near the mooring location.
Atmospheric CO2 forcing on glacial thermohaline circulation and climate
Authors: Liu ZhengYu , Shin Sang‐Ik , Webb Robert S. , Lewis William , Otto‐Bliesner Bette L.
Published: January 2005

A coupled climate model study indicates the paleoclimate record of glacial thermohaline circulation (THC) and reversed deep‐sea temperature‐salinity (T‐S) distribution in the Atlantic can be explained largely by lower glacial atmospheric CO2 alone. The reduced CO2 leads to increased Southern Ocean wintertime sea‐ice cover and salinity, increased production of dense Antarctic Bottom Water (AABW), enhanced cold and saline AABW penetration into the deep North Atlantic, increased oceanic vertical stability, and reduced North Atlantic Deep Water (NADW) circulation. The dominant role of CO2 forcing during the glacial implies a positive feedback between the Southern Ocean regulated THC and the glacial global carbon cycle.
Modeling of in situ ultrafine atmospheric particle formation in the eastern United States
Authors: Gaydos Timothy M. , Stanier Charles O. , Pandis Spyros N.
Published: January 2005

The creation of new atmospheric particles from in situ nucleation influences climate through cloud‐aerosol interactions and may negatively impact human health. Although recent observations show that nucleation is widespread in the eastern United States, the corresponding pathways remain uncertain. Combining extensive field measurements in Pittsburgh, Pennsylvania, with an aerosol dynamics and chemistry model assuming ternary NH3‐H2SO4‐H2O nuclei formation, we show excellent model‐measurement agreement and predictive capability. The ternary NH3‐H2SO4‐H2O nucleation model is successful in predicting the presence or lack of nucleation on 19 out of 19 days with complete data sets in July 2001 and on 25 out of 29 days in January 2002. Reductions of ammonia emissions are predicted to decrease the frequency of nucleation events during both summer and winter, with a more dramatic effect during the summer. The response to changes in emissions of sulfur dioxide during the summer is counterintuitive. Reductions of sulfur dioxide and the resulting sulfate by up to 40% actually increase the frequency of the summer nucleation events. Modeling predicts the opposite effect in winter, with reductions of sulfur dioxide leading to fewer nucleation events.
Kelvin wave variability near the equatorial tropopause observed in GPS radio occultation measurements
Authors: Randel William J. , Wu Fei
Published: January 2005

Temperature fields in the equatorial upper troposphere and lower stratosphere, derived from GPS radio occultation measurements for 2001–2002, show evidence for planetary‐scale Kelvin waves. These waves have a characteristic eastward phase tilt with height and typical vertical wavelengths of ∼4–8 km. The Kelvin waves exhibit coherent vertical structure over ∼12–25 km, with maximum amplitudes near the tropical tropopause (∼17 km). The waves are often quasi‐stationary near the tropopause but exhibit regular eastward propagation in the lower stratosphere (with periods near 20 days). The quasi‐stationary waves modulate the climatological cold tropopause over Indonesia. The transient lower stratospheric waves show enhanced amplitudes coincident with the descending westerly shear phase of the quasi‐biennial oscillation (QBO). Correlations with outgoing long‐wave radiation (OLR) data show that global temperature patterns over ∼12–17 km (with characteristic Kelvin wave structure) vary coherently with transient deep convection over Indonesia.
A global comparison of surface and free‐air temperatures at high elevations
Authors: Pepin N. C. , Seidel Dian J.
Published: January 2005

Surface and free‐air temperature observations from the period 1948–2002 are compared for 1084 surface locations at high elevations (>500 m) on all continents. Mean monthly surface temperatures are obtained from two homogeneity adjusted data sets: Global Historical Climate Network (GHCN) and Climatic Research Unit (CRU). Free‐air temperatures are interpolated both vertically and horizontally from the National Centers for Environmental Prediction/National Center for Atmospheric Research Reanalysis R1 2.5° grids at given pressure levels. The compatibility of surface and free‐air observations is assessed by examination of the interannual variability of both surface and free‐air temperature anomalies and the surface/free‐air temperature difference (ΔT). Correlations between monthly surface and free‐air anomalies are high. The correlation is influenced by topography, valley bottom sites showing lower values, because of the influence of temporally sporadic boundary layer effects. The annual cycle of the derived surface/free‐air temperature difference (ΔT) demonstrates physically realistic variability. Cluster analysis shows coherent ΔT regimes, which are spatially organized. Temporal trends in surface and free‐air temperatures and ΔT are examined at each location for 1948–1998. Surface temperatures show stronger, more statistically robust and widespread warming than free‐air temperatures. Thus ΔT is increasing significantly at the majority of sites (>70%). A sensitivity analysis of trend magnitudes shows some reliance on the time period used. ΔT trend variability is dominated by surface trend variability because free‐air trends are weak, but it is possible that reanalysis trends are unrealistically small. Results are sensitive to topography, with mountaintop sites showing weaker ΔT increases than other sites (although still positive). There is no strong relationship between any trend magnitudes and elevation. Since ΔT change is dependent on location, it is clear that temperatures at mountain sites are changing in ways contrasting to free air.
On the use of lumped sources in lightning return stroke models
Authors: Baba Yoshihiro , Rakov Vladimir A.
Published: January 2005

We consider the use of lumped voltage and current sources in engineering lightning return stroke models with emphasis on those including a tall strike object. If the model is to be used for computing remote electric and magnetic fields, we suggest a representation of the lightning channel as a transmission line energized by a lumped voltage source, with the voltage magnitude being expressed in terms of the lightning short‐circuit current and equivalent impedance of the lightning channel. Such a representation assures appropriate boundary conditions (reflection and transmission coefficients) at the channel attachment point and is equivalent to a distributed‐shunt‐current‐source representation of the lightning channel. This is in contrast with the use of series ideal current source which presents infinitely large impedance to current waves reflected from the ground and/or from discontinuities in the lightning channel, such as the moving return stroke front or branches, and therefore is inadequate when such reflections are involved. If the model is to be used only for injecting lightning current into a grounded object or system, a Norton equivalent circuit (an ideal current source in parallel with the equivalent impedance of the lightning channel) is sufficient to represent the lightning discharge.
Analysis of finite microstrip structures using an efficient implementation of the integral equation technique
Authors: Quesada Pereira F. , Gomez Tornero J. L. , Cañete Rebenaque D. , Pascual Garcia J. , Alvarez Melcon A.
Published: January 2005

An efficient numerical implementation of the integral equation technique (IE) has been developed for the analysis of the electrical characteristics of finite microstrip structures. The technique formulates a volume version of the IE for the finite dielectric objects and a standard surface IE technique for the metallic areas. The system of integral equations formulated is solved with special numerical techniques described in this paper. The input impedances of several microstrip antennas have been computed, showing good agreement with respect measurements. The technique has shown to be accurate, even for complex geometries containing several stacked dielectric layers. The radiation patterns of the structures have also been computed, and measured results from real manufactured hardware confirm that backside radiation and secondary lobes are accurately predicted by the theoretical model. The paper also discuss a suitable excitation model for finite size ground planes and investigates the possibilities for an independent meshing of the metallic areas and the dielectric objects inside a given geometry. The practical value of the approach derived is that microstrip circuits can be designed, minimizing the volume and size of the dielectric substrates.
Effective properties of two‐phase flow in heterogeneous aquifers
Authors: Jacobs Bruce , Gelhar Lynn W.
Published: January 2005

The spectral perturbation approach is employed to predict the field‐scale relative permeabilities and the variance of capillary pressure and saturation under steady two‐phase flow conditions. The theoretical analysis treats stationary three‐dimensional variations in pressure and flow produced as a result of spatial variations of permeability and two‐phase flow characteristics. The analysis is developed in a general form that is applied to different commonly used two‐phase flow characterizations, and results are illustrated for two‐phase flow characteristics corresponding to those observed at the Borden site in Canada. For gravity‐driven flow in horizontally layered aquifers, both nonwetting phase flow (dense nonaqueous phase liquid (DNAPL) flow) and wetting phase flow (water, unsaturated flow) show effective vertical relative permeabilities that are substantially decreased in comparison with those corresponding to a homogeneous system. The resulting saturation‐dependent anisotropy of effective permeability is substantially larger for DNAPL flow than for the case of unsaturated flow. The Leverett scaling characterization frequently used in Monte Carlo simulations is shown to underestimate system anisotropy owing to omission of variability of the parameter governing the slope in the capillary pressure–saturation function. Application of the Brooks‐Corey characterization of the relative permeability resulted in significantly greater anisotropy than with the van Genuchten characterization. In contrast to the strong influence of heterogeneity predicted in the case of effective permeabilities, the effective capillary pressure characteristic (mean capillary pressure versus mean saturation curve) is only weakly influenced by heterogeneity.
Analytical solutions to statistical moments for transient flow in two‐dimensional, bounded, randomly heterogeneous media
Authors: Lu Zhiming , Zhang Dongxiao
Published: January 2005

In this paper we derive analytical solutions to statistical moments for transient saturated flow in two‐dimensional, bounded, randomly heterogeneous porous media. By perturbation expansions, we first derive partial differential equations governing the zeroth‐order head h(0) and the first‐order head term h(1), where orders are in terms of the standard deviation of the log transmissivity. We then solve h(0) and h(1) analytically, both of which are expressed as infinite series. The head perturbation h(1) is then used to derive expressions for autocovariance of the hydraulic head and the cross covariance between the log transmissivity and head. The expressions for the mean flux and flux covariance tensor are formulated from the head moments based on Darcy's law. Using numerical examples, we demonstrate the convergence of these solutions. We also examine the accuracy of these first‐order solutions by comparing them with solutions from both Monte Carlo simulations and the numerical moment equation method.
Leaf lipids of Ribes nigrum: a plant containing 16:3, α-18:3, γ-18:3 and 18:4 fatty acids
Authors: Dobson G.
Published: January 2005

The glycerolipid composition of Ribes nigrum (blackcurrant) leaves was determined. The total fatty acid composition was unusual in that α-linolenic acid (α-18:3) occurred together with cis-7,10,13-hexadecatrienoic acid (16:3) and lower amounts of stearidonic acid (18:4) and γ-linolenic acid (γ-18:3). Monogalactosyldiacylglycerol contained the highest proportion of 16:3 with less in digalactosyldiacylglycerol. γ-18:3 and 18:4 were present in all lipids and 18:4 was always greater than γ-18:3. The highest percentages of γ-18:3 and 18:4 were in phosphatidylcholine, but phosphatidylglycerol was particularly low in these acids. In summary, the lipid composition was largely typical of 16:3 plants but there was a minor contribution typical of 18:4 plants. The possibility of three pathways for glycolipid biosynthesis is discussed.
Determination of glycerolipid composition of rice and maize tissues using solid-phase extraction
Authors: Rizov I. , Doulis A.
Published: January 2005

Currently available techniques for the separation and characterization of different glycerolipids are complicated and/or time consuming. By modulating the stationary phase in a solid-phase extraction (SPE) manifold, efficient and rapid separation of plant membrane lipids was achieved. The glycerolipids from rice and maize tissues were separated into seven classes (monogalactosyldiacylglycerol, digalactosyldiacylglycerol, phosphatidylethanolamine, phosphatidylcholine, sulphoquinovosyldiacylglycerol, phosphatidylinositol and phosphatidylglycerol). The pigments present in the rice and maize leaves and rice stems were successfully removed from the total lipid extracts. Pigment-free plant tissue (rice roots) was also analysed. The fatty acid profile of each lipid class isolated by SPE agreed well with those obtained by other separation techniques. The recovery of glycerolipids was at least 87°.
Molecular biology of acetyl-CoA metabolism
Authors: Nikolau B. J. , Oliver D. J. , Schnable P. S. , Wurtele E. S.
Published: January 2005

We have characterized the expression of potential acetyl-CoA-generating genes (acetyl-CoA synthetase, pyruvate decarboxylase, acetaldehyde dehydrogenase, plastidic pyruvate dehydrogenase complex and ATP-citrate lyase), and compared these with the expression of acetyl-CoA-metabolizing genes (heteromeric and homomeric acetyl-CoA carboxylase). These comparisons have led to the development of testable hypotheses as to how distinct pools of acetyl-CoA are generated and metabolized. These hypotheses are being tested by combined biochemical, genetic and molecular biological experiments, which is providing insights into how acetyl-CoA metabolism is regulated.