bluuebunny/crossref_metadata_2025 huggingface dataset:
Degradation of imazosulfuron in soil
Authors: Morrica Patrizia , Giordano Anita , Seccia Serenella , Ungaro Francesca , Ventriglia Mariacarla
Published: August 2002

Imazosulfuron, 1‐(2‐chloroimidazo[1,2‐a]pyridin‐3‐ylsulfonyl)‐3‐(4,6‐dimethoxypyrimidin‐2‐yl)urea, is a new post‐emergence sulfonylurea herbicide applied once per growing season, highly active at low application levels, used to control most annual and perennial broad‐leaf weeds and sedges in paddy rice (75–95 g AI ha−1) and turf (500–1000 g AI ha−1), and characterised by low mammalian toxicity. The degradation of imazosulfuron in a sandy loam soil (10–15 cm depth) has been investigated under aerobic and anaerobic laboratory conditions to evaluate its likely environmental fate. Test soils were treated with imazosulfuron in acetonitrile to give a final concentration of 0.2 mg kg−1 (100 g ha−1). The treated soils were extracted with methylene chloride + acetonitrile + 1 M ammonium hydroxide (4 + 15 + 1 by volume) and analysed by HPLC. Recoveries from spiked soils ranged from 80% to 95% (RSD 0.5–2.5%; n  = 3) for imazosulfuron and its metabolites 2‐chloroimidazo[1,2‐a]pyridin‐3‐sulfonamide (IPSN), 1‐(2‐chloroimidazo[1,2‐a]pyridin‐3‐ylsulfonyl)‐3‐(4‐hydroxy‐6‐methoxypyrimidin‐2‐yl)urea (HMS) and 2‐amino‐4,6‐dimethoxypyrimidine (ADPM). The limits of quantitation ranged from 0.001 mg kg−1 to 0.005 mg kg−1. Chemical cleavage of the sulfonylurea bond to give ADPM and IPSN was the main degradation pathway in aerobic conditions, whereas a remarkable production of HMS under anaerobic conditions suggested that degradation was due to micro‐organisms which had the ability to demethylate imazosulfuron. In aerobic and anaerobic conditions, imazosulfuron disappeared from the soil with a half‐life of approximately 70 (90% CL 62–75; r2 = 0.98) and 4 (90% CL 3.2–4.2; r2  = 0.97) days, respectively.

© 2001 Society of Chemical Industry
The hydroxyanilide fenhexamid, a new sterol biosynthesis inhibitor fungicide efficient against the plant pathogenic fungus Botryotinia fuckeliana (Botrytis cinerea)
Authors: Debieu Danièle , Bach Jocelyne , Hugon Mickael , Malosse Christian , Leroux Pierre
Published: August 2002

Fenhexamid, a recently developed botryticide, is shown here to inhibit sterol biosynthesis. When the fungus Botryotinia fuckeliana was grown in the presence of fenhexamid, the ergosterol content was reduced, and three 3‐keto compounds, 4α‐methylfecosterone, fecosterone and episterone, accumulated, suggesting an inhibition of the 3‐keto reductase involved in C‐4 demethylation. Thus, fenhexamid belongs to a new, promising class of sterol biosynthesis inhibitors not previously used in agriculture or in medicine.

© 2001 Society of Chemical Industry
Development of vaccines against sea lice
Authors: Raynard Robert S , Bricknell Ian R , Billingsley Peter F , Nisbet Alasdair J , Vigneau Antoine , Sommerville Christina
Published: August 2002

A review of efforts to develop a vaccine against sea lice is presented together with analysis of the rationale behind the approaches and potential future directions. Vaccines against the caligid copepod, Lepeophtheirus salmonis, have the potential to be a cost‐effective means of controlling the infection and avoid many of the disadvantages of medicine treatments. However, research towards such vaccines is in its infancy and approaches so far used have met with little or no success. Most strategies for sea louse vaccines have adopted methods used for vaccines against other ectoparasites. A vaccine against the cattle tick (Boophilus microplus) is in field use while other vaccines such as the sheep blowfly (Lucilia cuprina) vaccine are at an earlier stage of development. These haematophageous parasites ingest host antibody as part of a large blood meal which can target antigenic sites in the gut. However, the assumption that arachnid and insect physiology are directly comparable with that of sea lice is not proven, and this may partly explain the slow progress this approach has had with sea lice. Success in developing a louse vaccine will depend upon a better understanding of louse digestive biology, particularly an evaluation of whether the cattle tick model is applicable to the development of a louse vaccine. If the louse gut is to be targeted immunologically, critical antigens will need to be identified and evaluated, bearing in mind that an economic vaccine must include recombinant proteins or be a DNA vaccine. Alternatives to the louse gut as a target are also worth consideration. Antibodies could target critical host–parasite interactions that are amenable to disruption, although no such targets have been identified.

© 2002 Society of Chemical Industry
Analysis of masonry arches and vaults
Authors: Boothby Thomas E.
Published: August 2002

A growing interest in the preservation of historic structures has created a need for methods for the analysis of load‐bearing unreinforced masonry structures, such as arches, vaults, and buttresses. Although the plasticity methods, first applied to medieval structures in detail by Heyman, provide a useful and intuitive approach to the understanding of the behaviour of masonry arches and vaults, their usefulness in performing actual assessments of such structures has limitations. The constitutive laws of the materials used in masonry structures are not always amenable to accurate treatment by the rigid–plastic simplification, and the complexity of many vaulted masonry structures makes the application of these methods difficult. Moreover, empirical studies have shown that these structures may be subject to three‐dimensional effects that are not entirely addressed by the application of plastic or elastic analysis in two dimensions. Progress has been made recently in the development of constitutive laws for ancient masonry structures and in the application of these to the analysis of unreinforced masonry structural systems. Various formulations of three‐dimensional finite element analysis, including discrete element methods, and plasticity methods have also proven useful.
Antiinflammatory, analgesic and free radical scavenging activities of the marine microalgaeChlorella stigmatophora andPhaeodactylum tricornutum
Authors: Guzmán S. , Gato A. , Calleja J. M.
Published: August 2002

A pharmacological study of hydrosoluble and liposoluble extracts of the marine microalgae Chlorella stigmatophora and Phaeodactylum tricornutum indicated that hydrosoluble components of both species show significant antiinflammatory, analgesic and free radical scavenging activity. These activities were not detected in the liposoluble fractions. Copyright © 2001 John Wiley & Sons, Ltd.
A comparison of three estimators of the Weibull parameters
Authors: Skinner Katina R. , Keats J. Bert , Zimmer William J.
Published: August 2002

Using mean square error as the criterion, we compare two least squares estimates of the Weibull parameters based on non‐parametric estimates of the unreliability with the maximum likelihood estimates (MLEs). The two non‐parametric estimators are that of Herd–Johnson and one recently proposed by Zimmer. Data was generated using computer simulation with three small sample sizes (5, 10 and 15) with three multiply‐censored patterns for each sample size. Our results indicate that the MLE is a better estimator of the Weibull characteristic value, θ, than the least squares estimators considered. No firm conclusions may be made regarding the best estimate of the Weibull shape parameter, although the use of maximum likelihood is not recommended for small sample sizes. Whenever least squares estimation of both Weibull parameters is appropriate, we recommend the use of the Zimmer estimator of reliability. Copyright © 2001 John Wiley & Sons, Ltd.
Reliability qualification of semiconductor devices based on physics‐of‐failure and risk and opportunity assessment
Authors: Gerling W. H. , Preussger A. , Wulfert F. W.
Published: August 2002

Qualification frequently is a time‐critical activity at the end of a development project. As time‐to‐market is a competitive issue, the most efficient qualification efforts are of interest. A concept is outlined, which proactively integrates qualification into the development process and provides a systematic procedure as a support tool to development and gives early focus on required activities. It converts requirements for a product into measures of development and qualification in combination with a risk and opportunity assessment step and accompanies the development process as a guiding and recording tool for advanced quality planning and confirmation. The collected data enlarge the knowledge database for DFR/BIR (designing for reliability/building‐in reliability) to be used for future projects. The procedure challenges and promotes teamwork of all the disciplines involved. Based on the physics‐of‐failure concept the reliability qualification methodology is re‐arranged with regard to the relationships between design, technology, manufacturing and the different product life phases at use conditions. It makes use of the physics‐of‐failure concept by considering the potential individual failure mechanisms and relates most of the reliability aspects to the technology rather than to the individual product design. Evaluation of complex products using common reliability models and the definition of sample sizes with respect to systematic inherent product properties and fractions of defects are discussed. Copyright © 2002 John Wiley & Sons, Ltd.
Ab initio quantum chemical studies of reactions in astrophysical ices. 4. Reactions in ices involving HCOOH, CH2NH, HCN, HNC, NH3, and H2O
Authors: Woon David E.
Published: August 2002

Ice‐bound condensed‐phase reactions involving formic acid (HCOOH), methylenimine (CH2NH), hydrogen cyanide (HCN), hydrogen isocyanide (HNC), and ammonia (NH3) were investigated in order to characterize possible pathways to larger organic species that are efficient at the cold temperatures prevalent in cometary nuclei and the interstellar medium. Previous laboratory and computational modeling has demonstrated that reactions between some closed‐shell species can be significantly enhanced when they occur within a matrix of water ice. Certain key reactions can occur at temperatures under 100 K, in spite of having gas phase barriers that may be 30 kcal/mol or higher. The present study considered one‐ and two‐step reactions of HCOOH and NH3 to yield formamide (NH2CHO), reactions between CH2NH and HCN, HNC, NH3, and H2O, and the reaction of HCOOH and CH2NH to yield glycine (NH2CH2COOH). The most favorable process identified in this work is production of NH2CH(OH)2, the intermediate in the two‐step pathway from HCOOH and NH3 to NH2CHO, which is enhanced considerably when it occurs within ice but not to the extent that it is likely to occur unassisted at temperatures below 100 K. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem 88: 226–235, 2002
Phthalocyanoiron complex with bridged ligands. Electronic structure of monomers and polymers
Authors: Mendizabal Fernando , Olea‐Azar Claudio , Briones Rodolfo
Published: August 2002

Electronic structure aspects related to the semiconducting properties of monomers and polymers of phthalocyanoiron with bidentate bridging ligands, PcFe–L2 and [PcFe(L)]n, have been investigated from density functional calculations [L = pyrazine, triazine, tetrazine, pyridine, 4,4′‐bipyridine, bipyridyacetylene, and bis(4‐pyridyl)bencene]. The following relevant results have been obtained: (a) an energy analysis in terms of electrostatic interaction, Pauli repulsion, and occupied/virtual orbital interactions show that the Pauli repulsion is the origin that the axial ligands (L) prefer be located toward the aza positions of the macrocycle, and (b) the intrinsic semiconducting properties depend of the frontier band. The valence band is composed largely by the transition metal dxy orbital. The conduction band is composed of a mixture between the metallomacrocycle and bridged ligand orbitals for systems formed by pyrazine, bipyridine, and bipyridyacetylene. However, this composition is different when the ligands are triazine and tetrazine, which show a band composed of π* orbitals. These systems are predicted to show the higher conductivity within the series, in agreement with experimental results. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 82: 170–181, 2001
High‐speed liquid chromatography/tandem mass spectrometry using a monolithic column for high‐throughput bioanalysis
Authors: Wu Jing‐Tao , Zeng Hang , Deng Yuzhong , Unger Steve E.
Published: August 2002

With the ever‐increasing workload from a variety of in vitro and in vivo screening procedures, new analytical methodologies to perform bioanalysis in an accurate and high‐throughput manner are in great demand. In this work, monolithic columns were used instead of conventional particulate HPLC columns to perform chromatographic separations. Because the pressure drop on a monolithic column was considerably lower than that on a particulate column, a high flow rate (6 mL/min) was used for a 4.6 × 50 mm monolithic column with a total backpressure of about 61 bar measured using acetonitrile/water (50 : 50). The capability of using a regular column length at high flow rates, combined with the extremely small dependency of separation efficiency on linear flow velocity, allowed for the generation of sufficient chromatographic resolving power in a significantly reduced runtime. As demonstrated in this work, a plasma extract of a mixture of tempazepam, tamoxifen, fenfluramine, and alprozolam were baseline separated within a total analysis time of one minute. An average peak width at half maximum of approximately one second was noted using a generic broad gradient. It was also found that the separation efficiency and signal/noise (S/N) ratios for this separation remained almost constant at flow rates of 1, 3, and 6 mL/min, respectively. The ruggedness of the separation was evaluated by injecting 600 plasma extracts containing the replicates of a standard curve of the above mixture during an overnight run. The chromatographic retention time, separation quality, peak response and sensitivity were highly reproducible throughout the run. This high‐speed liquid chromatography/tandem mass spectrometry (LC/MS/MS) system has been used routinely in the authors' laboratory to support drug discovery programs. Copyright © 2001 John Wiley & Sons, Ltd.
Analysis of Synthetic chemical drugs in adulterated Chinese medicines by capillary electrophoresis/electrospray ionization mass spectrometry
Authors: Cheng Hsing Ling , Tseng Mei‐Chun , Tsai Pei‐Lun , Her Guor Rong
Published: August 2002

Sixteen synthetic chemical drugs, often found in adulterated Chinese medicines, were studied by capillary electrophoresis/UV absorbance (CE/UV) and capillary electrophoresis/electrospray ionization mass spectrometry (CE/ESI‐MS). Only nine peaks were detected with CZE/UV, but on‐line CZE/MS provided clear identification for most compounds. For a real sample of a Chinese medicinal preparation, a few adulterants were identified by their migration times and protonated molecular ions. For coeluting compounds, more reliable identification was achieved by MS/MS in selected reaction monitoring mode. Micellar electrokinetic chromatography (MEKC) using sodium dodecyl sulfate (SDS) provided better separation than capillary zone electrophoresis (CZE), and, under optimal conditions, fourteen peaks were detected using UV detection. In ESI, the interference of SDS was less severe in positive ion mode than in negative ion mode. Up to 20 mM SDS could be used in direct coupling of MEKC with ESI‐MS if the mass spectrometer was operated in positive ion mode. Because of better resolution in MEKC, adulterants can be identified without the use of MS/MS. Copyright © 2001 John Wiley & Sons, Ltd.
Evaluation of pyridoindoles, pyridylindoles and pyridylpyridoindoles as matrices for ultraviolet matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry
Authors: Nonami Hiroshi , Wu Feiyue , Thummel Randolph P. , Fukuyama Yuko , Yamaoka Hidenobu , Erra‐Balsells Rosa
Published: August 2002

In an effort to gain an understanding of the processes governing ultraviolet matrix‐assisted laser desorption/ionization (UV‐MALDI), direct comparison was made of the mass spectra of proteins, carbohydrates and synthetic polymers (polyethylene glycol, polyester and polyamide) by using pyridylindoles, pyridoindoles and pyridylpyridoindoles as UV (337 nm)‐MALDI‐TOFMS matrices in positive and negative ion mode. In order to study the combined effect of the indole N‐H and the pyridine nitrogen of the MALDI matrix on the desorption/ionization process in MALDI, compounds were selected that include either or both of these functions in their structure. Within the compounds studied only those that possess simultaneously both functions in a 1,4‐relation behave as very good matrices for proteins. These compounds also work as matrices for some carbohydrates and synthetic polymers used as analytes in the present study. Some of the compounds were also found to be useful for the post‐source decay (PSD) analysis of cyclodextrins in positive and negative ion mode. In several cases we also examined the matrix behavior of the corresponding N‐methylindole derivatives. Copyright © 2001 John Wiley & Sons, Ltd.
Micro‐high‐performance liquid chromatography/Fourier transform mass spectrometry with electron‐capture dissociation for the analysis of protein enzymatic digests
Authors: Davidson Walter , Frego Lee
Published: August 2002

Electron‐capture dissociation (ECD) Fourier transform mass spectrometry (FTMS) employed to generate comprehensive sequence information for the chromatographic analysis of enzymatic protein digests is described. A pepsin digest of cytochrome c was separated by reversed‐phase micro‐high‐performance liquid chromatography (µHPLC) and ionized ‘on‐line’ by electrospray ionization (ESI). The ions thus formed were transferred to and trapped in the FTMS analyzer cell. Typically, no precursor ion isolation was performed. The trapped ions were subjected to a pulse of electrons to induce fragmentation. Mass spectra were acquired continuously to produce a three‐dimensional LC/MS data set. The spectra were dominated by c and, to a lesser degree, z ions, which provided near complete sequence coverage. External calibration provided good mass accuracy and resolution, typical of FTMS. Thus µHPLC/ECD − FTMS is shown to be a highly informative method for the analysis of enzymatic protein digests. Copyright © 2002 John Wiley & Sons, Ltd.
New IQC for quasi‐concave nonlinearities
Authors: Megretski Alexandre
Published: August 2002

A new set of integral quadratic constraints (IQC) is derived for a class of ‘rate limiters’, modelled as a series connections of saturation‐like memoryless nonlinearities followed by integrators. The result, when used within the standard IQC framework (in particular, with finite gain/passivity‐based argiments, Lyapunov theory, structured singular values, etc.), is expected to be widely useful in nonlinear system analysis. For example, it enables ‘discrimination’ between ‘saturation‐like’ and ‘deadzone‐like’ nonlinearities and can be used to prove stability of systems with saturation in cases when replacing the saturation block by another memoryless nonlinearity with equivalent slope restrictions makes the whole system unstable. In particular, it is shown that the L2 gain of a unity feedback system with a rate limiter in the forward loop cannot exceed \sqrt{2}.

In addition, a new, more flexible version of the general IQC analysis framework is presented, which relaxes the homotopy and boundedness conditions, and is more aligned with the language of the emerging IQC software. Copyright © 2001 John Wiley & Sons, Ltd.
Effects of river regulation on aquatic macrophyte growth and floods in the Hadejia‐Nguru Wetlands and flow in the Yobe River, northern Nigeria; implications for future water management
Authors: Goes B.J.M.
Published: August 2002

The Hadejia River is a tributary of the Yobe River in semi‐arid northern Nigeria and is regulated by two major dams. The other main tributary is uncontrolled. Comparison of the discharge data for the controlled and uncontrolled rivers shows an average decrease of 33% in annual flow in the upstream part of the Hadejia River. The total annual flow and the peak flow in the Hadejia River further downstream, just above the Hadejia‐Nguru Wetlands (HNW), however, did not show a significant reduction in discharge. This is related to a relatively small river flow reduction at lower flows in the upstream part of the Hadejia River and the fact that the formal large upstream water users are not (yet) working at full capacity. The major impact of the dams on the downstream part of the river is the change in regime from ephemeral to perennial. The introduced dry season flows created favourable circumstances for the development of aquatic macrophyte blockages in the HNW. Owing to these blockages, the Hadejia River stopped contributing to the flow in the Yobe River for much of the year. Furthermore, after the completion of the dams, the timing of the floods in the HNW became less predictable.

Suggestions for improvement of water management are made. These comprise engineering structures, including a flow diversion structure to regulate flows in the HNW, implementation of environmentally acceptable river flow strategies and water allocation management. Copyright © 2002 John Wiley & Sons, Ltd.
Propagules in dry wetland sediments as indicators of ecological health: effects of salinity
Authors: Skinner Rachael , Sheldon Fran , Walker Keith F.
Published: August 2002

Indicators of ecological health are problematic for wetlands in dry regions because distinctive communities are associated with dry and wet phases of indefinite duration. The propagule bank, including the resting stages of aquatic animals and plants, maintains the community's capacity to recover from drought or disturbance. This paper records observations of invertebrates, protists and algae emerging in laboratory microcosms following the inundation of dry sediments from two temporary lakes on the River Murray floodplain in South Australia. A simple experiment carried out on the sediment from one lake showed that increased salinity was associated with lower diversity (richness) but higher abundance of emergent organisms. The effect on diversity was evident at salinities above 11–17 mS cm−1, and the effect on abundances was evident above 6–11 mS cm−1 (salinity here is indicated by electrical conductivity at 25°C). These data suggest that propagule banks may be useful as complementary indicators of wetland health. Copyright © 2001 John Wiley & Sons, Ltd.
Summary of ISO/TC 201 Standard: VI ISO 14706:2000—Surface chemical analysis—Determination of surface elemental contamination on silicon wafers by total reflection x‐ray fluorescence (TXRF) spectroscopy
Authors: Gohshi Yohichi
Published: August 2002

This International Standard specifies a total reflection x‐ray fluorescence (TXRF) method for the measurement of the atomic surface density of elemental contamination on chemomechanically polished or epitaxial silicon wafer surfaces. This method is applicable to elements with atomic number from 16 (S) to 92 (U), and contamination elements with atomic surface densities from 1 × 1010 to 1 × 1014 atoms cm−2. It is applicable also to contamination elements with atomic surface densities of 5 × 108–5 × 1012 atoms cm−2 using a vapour‐phase decomposition specimen preparation method. Copyright © 2002 John Wiley & Sons, Ltd.
Statistical considerations of FDA and CPMP rules for the investigation of new anti‐bacterial products
Authors: Röhmel Joachim
Published: August 2002

In this paper I investigate statistical properties of some guidance given by the FDA and by the CPMP on the planning, conduct and analysis of clinical trials with new anti‐bacterial substances using an active control design. It is demonstrated that the non‐inferiority margin proposed by the FDA has some undesirable features, and that the CPMP guidance may need further interpretation with respect to a statement that the non‐inferiority margin may be smaller than 10 per cent for response rates >90 per cent. A new margin is proposed that combines the desirable properties from both the FDA and the CPMP guidance. It is also shown that the approximate unconditional tests that are in use in such trials are quite unreliable with respect to preserving the nominal type I error. Unconditional exact tests are presented as a remedy for this issue. Copyright © 2001 John Wiley & Sons, Ltd.
Minor stressors and depressed mood: reactivity is more strongly correlated than total stress
Authors: Felsten Gary
Published: August 2002

This study evaluated how strongly total stress and stress reactivity to minor stressors were correlated with depressed mood in traditional and non‐traditional college women (n = 146). Stress reactivity, which was conceptualized as mean stress per stressor, accounted more strongly than number of potentially stressful encounters for total stress, and was more strongly correlated than total stress with symptoms of depressed mood, after controlling for initial depressed mood and neuroticism. Reactivity was associated with greater use of avoidance coping and higher levels of neuroticism, which suggest that it may represent a stable individual difference and possibly serve as a predictor of depressed mood, especially in response to minor stressors. Copyright © 2002 John Wiley & Sons, Ltd.
Influence of interferon‐γ on radiation‐induced apoptosis in normal and ataxia‐telangiectasia fibroblast cell lines
Authors: Savoldi‐Barbosa Marcela , Sakamoto‐Hojo Elza T.
Published: August 2002

Combination of interferon‐γ (IFN‐γ) with radiation, or chemotherapeutic agents, produces different kind of modulatory effects, depending on the cell types and experimental conditions. The objective of the present study was verify the influence of IFN‐γ on the induction of apoptosis by gamma‐radiation. Experiments were carried out on human fibroblast cell lines: VH‐25 (primary), MRC‐5, and AT‐5BIVA (SV40‐transformed). Exponentially growing cells were irradiated and exposed to IFN‐γ (1,000, 2,000, and 3,000 UI/mL) until in situ cell staining performed at 6, 24, and 48 h. Induction of apoptosis by ionising radiation was not verified in primary VH‐25 cells. A significant increase in the frequencies of apoptotic cells was observed in SV‐40‐transformed cells lines, MRC‐5, and AT‐5BIVA fibroblasts, which were irradiated with 1.0 Gy, but the frequencies of necrotic cells were similar to the control levels. In MRC‐5 cells, combined treatments with radiation and IFN‐γ induced a statistically significant reduction in the frequencies of apoptotic cells detected at 24 and 48 h after cell irradiation, while for AT cells the interaction effect (reduction of apoptosis frequency) was significant even at earlier time collection (6 h) after γ‐irradiation, and higher when compared to MRC‐5 cells. The present study demonstrated that IFN‐γ showed an anti‐apoptotic activity in SV40‐transformed fibroblasts, normal and AT cells, which were irradiated with γ‐rays, thus indicating a mechanism dependent on the cellular type. Teratogenesis Carcinog. Mutagen. 21:417–429, 2001. © 2001 Wiley‐Liss, Inc.
The two sites of fusion of the neural folds and the two neuropores in the human embryo
Authors: O'Rahilly Ronan , Müller Fabiola
Published: August 2002

Background

Since reports on a pattern of multiple sites of fusion of the neural folds in the mouse appeared, it has been widely assumed that a similar pattern must be valid for the human. In the absence of embryological evidence, claims have been made that such a pattern can be discerned by classifying neural tube defects.

Methods

The neural folds and tube, as well as the neuropores, were reassessed in 98 human embryos of Stages 8–13; 61 were controlled by precise graphic reconstructions.

Results

Careful study of an extensive series of staged human embryos shows that two de novo sites of fusion of the neural folds appear in succession: α in the rhombencephalic region and β in the prosencephalic region, adjacent to the chiasmatic plate. Fusion from Site α proceeds bidirectionally (rostrad and caudad), whereas that from β is unidirectional (caudad only). The fusions terminate in neuropores, of which there are two: rostral and caudal. Highly variable accessory loci of fusion, without positional stability and of unknown frequency, may be encountered in Stage 10 but seemingly not later, and their existence has been known for more than half a century.

Conclusions

Two sites of fusion (a term preferred to closure) of the neural folds and two neuropores are found in the human embryo. No convincing embryological evidence of a pattern of multiple sites of fusion, such as has been described in the mouse, is available for the human. The construction of embryological details from information derived from other species or from the examination of later anomalies is liable to error. Neural tube defects are reviewed and although they have been considered on the basis of five, four, or three sites of fusion, interpretations based on two sites can as readily be envisaged. Teratology 65:162–170, 2002. © 2002 Wiley‐Liss, Inc.
Doing business in Vietnam
Authors: Scheela William , Van Dinh Nguyen
Published: August 2002

This article examines the opportunities and challenges of doing business in Vietnam. We focus on the
seven‐year development process of the venture capital industry in Vietnam as an indicator of the
long‐term process of creating and managing business investments there. Although there are many lucrative
business opportunities in Vietnam, there are also significant challenges that must be carefully analyzed before
making an investment. Challenges include finding quality investments, long payback periods, a lengthy and expensive
process to develop a management team, and significant misunderstandings because of cultural differences between
Western and Vietnamese investors. © 2001 John Wiley & Sons, Inc.
Taking Student Criticism Seriously: Using Student Quality Teams to Guide Critical Reflection
Authors: Spence Larry , Lenze Lisa Firing
Published: August 2002

Using teams of students to provide reflective feedback can yield quality insights into ways to improve teaching and learning.
Cell‐free protein synthesis inhibition assay for the cyanobacterial toxin cylindrospermopsin
Authors: Froscio Suzanne M. , Humpage Andrew R. , Burcham Philip C. , Falconer Ian R.
Published: August 2002

The cyanobacterial toxin cylindrospermopsin (CYN) is known to be a potent inhibitor of protein synthesis. This paper describes the use of a rabbit reticulocyte lysate translation system as a protein synthesis inhibition assay for CYN. A dose response curve for protein synthesis inhibition by CYN was constructed and was modeled to a sigmoidal dose response curve with variable slope (R2=0.98). In this assay, CYN has an IC50 of 120 nM [95% chemical interaction (CI)=111−130 nM] with a detection limit in the region of 50 nM in the assay solution. Application of the assay allows quantification of toxin samples within the range 0.5–3.0 μM (200–1200 μg/L) CYN. To assess the usefulness of this assay, a range of toxic and nontoxic Cylindrospermopsis raciborskii extracts, including both laboratory strains and environmental samples, were assayed by protein synthesis inhibition. These CYN quantifications were then compared to quantifications obtained by high performance liquid chromatography (HPLC) and HPLC‐tandem mass spectrometry (HPLCMS–MS). The results demonstrate that the protein synthesis inhibition assay correlates well with both HPLCMS–MS (r2=0.99) and HPLC (r2=0.97) quantifications. We conclude that this is an accurate and rapid assay for the measurement of cylindrospermopsin in cyanobacterial extracts. © 2001 John Wiley & Sons, Inc. Environ Toxicol 16: 408–412, 2001
Identification of genes implicated in toxin production in the cyanobacterium Cylindrospermopsis raciborskii
Authors: Schembri Mark A. , Neilan Brett A. , Saint Christopher P.
Published: August 2002

Cylindrospermopsis raciborskii is a bloom‐forming cyanobacterium found in both tropical and temperate climates which produces cylindrospermopsin, a potent hepatotoxic secondary metabolite. This organism is notorious for its association with a significant human poisoning incident on Palm Island, Australia, which resulted in the hospitalization of 148 people. We have screened 13 C. raciborskii isolates from various regions of Australia and shown that both toxic and nontoxic strains exist within this species. No association was observed between geographical origin and toxin production. Polyketide synthases (PKSs) and peptide synthetases (PSs) are enzymes involved in secondary metabolite biosynthesis in cyanobacteria. Putative PKS and PS genes from C. raciborskii strains AWT205 and CYP020B were identified by PCR using degenerate primers based on conserved regions within each gene. Examination of the strain‐specific distribution of the PKS and PS genes in C. raciborskii isolates demonstrated a direct link between the presence of these two genes and the ability to produce cylindrospermopsin. Interestingly, the possession of these two genes was also linked. They were also identified in an Anabaena bergii isolate that was demonstrated to produce cylindrospermopsin. Taken together, these data suggest a likely role for these determinants in secondary metabolite and toxin production by C. raciborskii. © 2001 John Wiley & Sons, Inc. Environ Toxicol 16: 413–421, 2001
Synchrotron x‐ray fluorescence and secondary ion mass spectrometry in tree ring microanalysis: applications to dendroanalysis
Authors: Martin R. R. , Sham T. K. , Wong Won G , Jones K. W. , Feng H.
Published: August 2002

Mining operations in the Sudbury district of northern Ontario have resulted in environmental damage caused by acid rain and heavy metal pollution. Remedial liming (Ca/MgCO3) has been used in an attempt to restore the pH of the lake water and soil to natural levels. The spatial and temporal variation of metal concentrations in the annual growth rings of trees may be a useful indicator of the effects of the pollutants and the liming operation. We used synchrotron radiation‐induced x‐ray emission (SRIXE) and secondary ion mass spectrometry (SIMS) to examine the distribution of selected metals in the annual growth rings of red pine (Pinus resinosa) from an area damaged by acid rain and heavy metal pollution which had been subjected to remedial liming (Ca/MgCO3). The results show a non‐uniform distribution of metals in the stemwood, including seasonal variations and changes in the Ca/Mn ratio consistent with the increased soil pH following liming. Copyright © 2001 John Wiley & Sons, Ltd.
Evaluation of energy‐dispersive x‐ray spectra of low‐Z elements from electron‐probe microanalysis of individual particles
Authors: Osán J. , de Hoog J. , Van Espen P. , Szalóki I. , Ro C.‐U. , Van Grieken R.
Published: August 2002

Several applications require the determination of low‐Z elements such as C, N and O in individual microparticles. Electron‐probe microanalysis (EPMA) using a thin‐window energy‐dispersive x‐ray detector offers the possibility to detect light elements. To achieve at least semi‐quantitative information on the chemical composition of each individual particle, accurate determination of x‐ray intensities is critical. The energy‐dispersive x‐ray spectra under 1 keV are complex. The L and M lines of heavier elements can strongly overlap with light‐element K lines. Also, the transmission of the detector window and the shape of the bremsstrahlung background should be taken into account. Because of the strong overlap of the characteristic lines, the ‘top‐hat’ filter used for on‐line evaluation of conventional computer‐controlled EPMA spectra cannot be applied for thin‐window EPMA spectra under 1 keV. Therefore, the spectra were processed using a non‐linear least‐squares fitting algorithm (AXIL). The applicability and the limitations of the method were tested by a series of measurements of particulate standards in the size range of 0.3–10 µm, made from analytical‐reagent grade chemicals. The composition and thickness of the thin window of the detector were modelled using the transmission data given by the manufacturer. The elemental composition of each individual particle was approximated using a new data evaluation method (EP‐PROC) based on an iterative Monte Carlo simulation with combination of successive approximation. The dependence of the K/L intensity ratios of the elements Ca–Zn on the size and composition of the particles was studied extensively by Monte Carlo simulations and measurements of standard particles. By taking into account the L‐line contributions of K, Ca, Ti or Cr in the spectral evaluation, the estimation of the light‐element concentrations was improved significantly, especially when K, Ca, Ti or Cr were present at high concentrations. Copyright © 2001 John Wiley & Sons, Ltd.
Quality control of commercial tea by x‐ray fluorescence
Authors: Salvador Marcos J. , Lopes Guido N. , Nascimento Filho Virgílio F. , Zucchi Orghêda L. A. D.
Published: August 2002

Based on the energy‐dispersive x‐ray fluorescence (EDXRF) technique, the concentrations of elements (22 ≤ Z ≤ 30) were assessed in five kinds of commercial tea from six commercial suppliers: Matricaria chamomilla L. (camomile), Mentha piperita L. (mint), Cymbopogon citratus (DC) Stapf. (herb ‘cidreira’), Malus domestica Borkh. (apple tea) and Camellia sinensis (L.) O. Kuntze (black tea). The samples were excited by an x‐ray tube with an Mo anode (25 kV and 10 mA), with a Zr filter, and the characteristic x‐ray were detected by an Si(Li) detector coupled to a multichannel analyzer. Using standard samples, the relationship between the detection limit and the atomic numbers of Fe, Co, Ni, Cu and Zn was determined. In some tea samples Ti was detected, but it is not an essential microelement for the plant growth. Fe, Ni and Cu were detected in all tea samples analyzed; Ti, Cr, Co and Zn were detected in Matricaria chamomilla and Malus domestica; Ti, Co and Zn in Mentha piperita and Ti, Mn, Co and Zn in Cymbopogon citratus. The inorganic constitution profile of this matrix type and the fingerprints in the production process can be evaluated by employing the EDXRF quality control of the commercial products. Copyright © 2002 John Wiley & Sons, Ltd.
Characterization of porous microstructure by x‐ray microtomography
Authors: Appoloni Carlos R. , Macedo Álvaro , Fernandes Celso P. , Philippi Paulo C.
Published: August 2002

Knowledge of the porous structure of amorphous material is of fundamental importance in calculating geometric parameters such as total porosity, pore size distribution and physical parameters related to fluid flow inside void space. This work involved the measurement of microstructural parameters of petroleum reservoir rocks and porous ceramic filters. Microtomographic measurements of samples were performed by employing an x‐ray tube. Bremsstrahlung radiation was filtered in transmission mode with an Sn filter at 58.5 and 28.3 keV. The beam width was about 80 µm at the sample position center. Images were analyzed in two ways. In the first method, transepts of the images were analyzed in order to calculate the total porosity by means of the average particle and media linear attenuation coefficients. In the second method, images were studied using image analysis software, named Imago, allowing the calculation of total porosity and pore size distribution. The total measured porosity of the filter C90 was 73.8, 71.1, 74.4 and 71.5% using the Archimedes method, simple gamma‐ray transmission, transept and image analysis of the microtomography at 28.3 keV, respectively. Measured total porosity for one of the sandstones was 23.23, 24.70, 23.43, 29.68, 29.65 and 27.80% using Hg and gas porosimetry, the Archimedes method, simple gamma‐ray transmission and transept analysis of the microtomography at 58.5 and 28.2 keV, respectively. Copyright © 2002 John Wiley & Sons, Ltd.
CaALK8, an alkane assimilating cytochrome P450, confers multidrug resistance when expressed in a hypersensitive strain of Candida albicans
Authors: Lata Panwar Sneh , Krishnamurthy Shankarling , Gupta Vinita , Alarco Anne‐Marie , Raymond Martine , Sanglard Dominique , Prasad Rajendra
Published: August 2002

We report the isolation of a novel C. albicans gene designated CaALK8, by its ability to complement drug hypersensitivity of a pdr5 (ABC: ATP‐binding cassette drug extrusion pump) null mutant of S. cerevisiae (JG436). CaALK8 in JG436 conferred resistance to drugs such as cycloheximide (CYH), fluconazole (FCZ), O‐phenanthroline (PHE) and 4‐nitroquinoline oxide (NQO). The gene was so designated because its sequence was identical to a partial sequence entry named as ALK8 in the Candida database (http://alces.med.umn.edu/candida.html). CaALK8 encodes for a putative 515 amino acid protein highly homologous to alkane‐inducible cytochromes P450 (CYP52 gene family) of C. maltosa and C. tropicalis. The ability of CaALK8 to confer drug resistance was also established by its expression in another drug‐hypersensitive strain of S. cerevisiae (AD 1234568), which was deleted in seven ABC efflux pumps. The homozygous disruption of CaALK8 in a wild‐type C. albicans strain (CAI4) did not result in altered drug susceptibilities. The overexpression of CaALK8 in CAI4 resulted in only FCZ resistance. However, a distinct MDR phenotype was evident when CaALK8 was overexpressed in a drug‐hypersensitive C. albicans strain disrupted in both CDR1 and CDR2 (ABC drug extrusion pumps of C. albicans). Alk8p, similar to other Alk proteins from C. maltosa and C. tropicalis, could hydroxylate alkanes and fatty acids. In this study we demonstrate that several drugs could compete with the hydroxylation activity by directly interacting with CaAlk8p. Taken together, our results suggest that a member of the CYP52 gene family could mediate MDR in C. albicans, although it does not seem to be involved in the development of azole resistance in clinical isolates. The nucleotide sequence reported in this paper has been submitted to GenBank under Accession No. Y14766. Copyright © 2001 John Wiley & Sons, Ltd.
Hormonal and behavioral relationships during estrus in the giant panda
Authors: Lindburg D.G. , Czekala N.M. , Swaisgood R.R.
Published: August 2002

Nonlactating female giant pandas experience a single estrus during the spring mating season. Although both hormonal and behavioral aspects of estrus have been reported on captive females, little is known about the relationship between them. Data were collected on a single captive female during three successive seasons, revealing a high degree of regularity in both estrogen profiles and the temporal pattern of associated behaviors. The birth of a live cub in the last of the three seasons, using artificial insemination, confirmed the time of ovulation as occurring shortly after a peak in urinary estrogen values. In this study, we examined the occurrence of female scent marking, rear presentations, chirp and bleat vocalizations, and the tail‐up display, and plotted their occurrence relative to the underlying estrogen values. We conclude that the role of estrogen in the expression of these behaviors is neither simple nor directly causal. Temporal associations indicate that a triggering rather than a maintenance function for estrogen is implicated. This analysis provides a clear identification of estrous behaviors, but in both the time and form of occurrence these behaviors most likely vary between females and seasons. Zoo Biol 20:537–543, 2001. © 2002 Wiley‐Liss, Inc.
Automatic Verification of a Lip-Synchronisation Protocol Using Uppaal
Authors: Bowman H. , Faconti G. , Katoen J.-P. , Latella D. , Massink M.
Published: August 2002

We present the formal specification and verification of a lip-synchronisation protocol using the real-time model checker Uppaal. A number of specifications of this protocol can be found in the literature, but this is the first automatic verification. We take a published specification of the protocol, code it up in the Uppaal timed automata notation and then verify whether the protocol satisfies the key properties of jitter and skew. The verification reveals some aws in the protocol. In particular, it shows that for certain sound and video streams the protocol can time-lock before reaching a prescribed error state. We also discuss our experience with Uppaal, with particular reference to modelling timeouts and to deadlock analysis.
History of Clinical Transplantation
Authors: Starzl Thomas E.
Published: August 2002

The emergence of transplantation has seen the development of increasingly potent immunosuppressive agents, progressively better methods of tissue and organ preservation, refinements in histocompatibility matching, and numerous innovations in surgical techniques. Such efforts in combination ultimately made it possible to successfully engraft all of the organs and bone marrow cells in humans. At a more fundamental level, however, the transplantation enterprise hinged on two seminal turning points. The first was the recognition by Billingham, Brent, and Medawar in 1953 that it was possible to induce chimerism‐associated neonatal tolerance deliberately. This discovery escalated over the next 15 years to the first successful bone marrow transplantations in humans in 1968. The second turning point was the demonstration during the early 1960s that canine and human organ allografts could self‐induce tolerance with the aid of immunosuppression. By the end of 1962, however, it had been incorrectly concluded that turning points one and two involved different immune mechanisms. The error was not corrected until well into the 1990s. In this historical account, the vast literature that sprang up during the intervening 30 years has been summarized. Although admirably documenting empiric progress in clinical transplantation, its failure to explain organ allograft acceptance predestined organ recipients to lifetime immunosuppression and precluded fundamental changes in the treatment policies. After it was discovered in 1992 that long‐surviving organ transplant recipients had persistent microchimerism, it was possible to see the mechanistic commonality of organ and bone marrow transplantation. A clarifying central principle of immunology could then be synthesized with which to guide efforts to induce tolerance systematically to human tissues and perhaps ultimately to xenografts.
Longmire Lecture: My 50 Years at the University of California, Los Angeles
Authors: Terasaki Paul I.
Published: August 2002

The main concept driving my work has been the humoral theory of immunity to allografts. It led to the development of the microlymphocytotoxicity test, which is used to look for the relevant transplant antigens using alloantisera. Using alloantibodies produced by pregnancies, the HLA system was defined through a series of international histocompatibility workshops. It was then shown that the HLA system was important for matching donors and recipients for bone marrow transplants and organ transplants. More than 6000 HLA‐matched kidney transplants from cadaver donors have now been shared in the United States. HLA antigens were found to be of importance in anthropologic and disease susceptibility studies. Currently HLA antibodies are being studied intensively to determine their role in chronic rejection. If it is proven that these antibodies trigger intimal proliferation, occluding arterioles, HLA antibodies will become essential to the monitoring of chronic rejection.