bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of flooding regime upon the decomposition of Eichhornia azurea (Sw.) Kunth measured on a tropical, flow‐regulated floodplain (Paraná River, Brazil)
Authors: Padial André Andrian , Thomaz Sidinei Magela 
Published: June 2006

AbstractDecomposition of macrophytes is an important process in river‐floodplain systems, especially in the Upper Paraná River floodplain, given that this ecosystem receives high inputs of detritus from this vegetation. Release of nutrients by decomposition is essential in this floodplain because it is located downstream from a reservoir chain where nutrients are being trapped. Water level fluctuations are considered one of the most important aspects that affect macrophyte decomposition. Anthropogenic alterations, such as the control of flooding regimes, observed in this floodplain, could change the dynamic of this process. To evaluate the influence of the hydrological cycle upon the decomposition of Eichhornia azurea (an aquatic macrophyte that has high biomass values in this ecosystem), litter bags with senescent leaves and petioles of this plant were submitted to four different flooding treatments, which differed in time of flooding and exposure to dry conditions. The decomposition rates and the detritus chemical composition (nitrogen and phosphorus concentrations) were measured over 113 days. There were significant effects of the flooding treatments and time upon all parameters. The materials that decomposed with flood conditions showed the greatest decomposition rates. The quality of the detritus seems to be highly linked with the flooding regime, showing highest releases of phosphorus in the submerged treatments. It was shown that floods, even the short duration ones, increase the decomposition velocity and the nutrient cycling relative to dry conditions. Thus, investigations that assess the nutrient budgets on the Upper Paraná River floodplain and the role of nutrients in its productivity should consider the detritus compartment and the effects of flood regimes upon its dynamics. Copyright © 2006 John Wiley & Sons, Ltd.
‘A memorandum on the Present Position and Prospects of Medical Statistics and Epidemiology’ by Major Greenwood
Authors: Farewell Vern , Johnson Tony , Armitage Peter 
Published: June 2006

AbstractWe present an unpublished, possibly unsent, memorandum written by Major Greenwood in 1928 that is of historical importance. It raises three issues, namely, the profile of medical statistics in 1928, the development of mathematical statistics in the U.K., and the staffing of his own department. Some of these issues are still relevant today. We discuss each of them against the historical background of the first quarter of the 20th century. Some additional biographical details relevant to the understanding of the memorandum are provided in an Appendix.Copyright © 2006 John Wiley & Sons, Ltd.
Accuracy of fetal echocardiography: a cardiac segment‐specific analysis
Authors: Gottliebson W. M. , Border W. L. , Franklin C. M. , Meyer R. A. , Michelfelder E. C. 
Published: June 2006

AbstractObjectiveIn patients with congenital heart disease, comprehensive, segment‐specific analysis of cardiac anatomy has become ‘the standard of care’, largely as a result of improvements in cardiac imaging technology. Our aim was to apply segment‐specific standards to assess the accuracy of fetal echocardiography.MethodsThis was a retrospective review of all fetal echocardiograms (n = 915) performed at our center between August 1998 and June 2003. Of these, 100 studies had congenital heart disease findings and corresponding postnatal studies on the same patients for comparison. An expert independent pediatric echocardiologist, using the standards of accuracy expected of postnatal echocardiography, assessed the studies for the following cardiac segments: abdominal situs, systemic venous return (VR), pulmonary VR, atria, atrioventricular valves, ventricular septum, ventricular hypoplasia, ventricular morphology, semilunar valves, great arterial relation and aortic arch. Sensitivity, specificity, and positive and negative predictive values were calculated for each segment.ResultsSpecificity and negative predictive value were high for all cardiac segments (range, 82–100%). Sensitivity and positive predictive value were similarly high (range, 83–100%) for most cardiac segments, but were only 50–88% for systemic VR, pulmonary VR and aortic arch segments.ConclusionsFetal echocardiography has excellent diagnostic accuracy in describing intracardiac anatomy. However, despite both technological advances and improved physician awareness, assessment of systemic VR, pulmonary VR, and aortic arch anatomy remain challenging. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.
Assessment of the intraobserver variability in the measurement of fetal cardiothoracic ratio using ellipse and diameter methods
Authors: Awadh A. M. A. , Prefumo F. , Bland J. M. , Carvalho J. S. 
Published: June 2006

AbstractObjectiveTo assess the variability of fetal heart and thoracic area and circumference measurements using the ellipse and diameter methods at different gestational ages.DesignThis was a prospective cross‐sectional study of 200 singleton pregnancies, with no apparent fetal abnormalities. The gestational age ranged between 19 and 42 weeks. At each examination, two transverse frames of the fetal chest at the level of the four‐chamber view during diastole were obtained. For each frame, the area and the circumference of the heart and thorax were obtained by the ellipse and diameter methods. In the diameter method, cardiac and thoracic areas and circumferences were derived from the measured anteroposterior and transverse diameters. All measurements were made by the same observer.ResultsFor the same method, intraobserver variability was good. Coefficient of variation for all measurements varied between 3–11%. The ellipse method tended to give larger measurements than did the diameter method, the absolute difference increasing with fetal age. The mean ellipse/diameter ratio was 1.10, 1.04, 1.05 and 1.02 for heart area, thorax area, heart circumference and thorax circumference, respectively. In most cases, intraobserver variability of the thorax measurements was independent of gestational age. In contrast, there was a greater variability of heart measurements with increasing gestational age.ConclusionsBoth the ellipse and diameter methods of measuring cardiothoracic ratio are clinically useful and fairly reproducible at certain gestations, but are not interchangeable as the ellipse method overestimates measurements compared to the diameter method. The less reproducible measurement of heart size in later gestation should be taken into account when assessing cardiothoracic ratios. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.
Wasserpermeation durch Polymere und keramische Substrate
Authors: Hübner Susanne , Pulker H.K. 
Published: June 2006

AbstractFür die Messung der Wasserpermeation durch Scheiben aus TorrSeal (Epoxidharz), FIMO (PVC und Füllstoffe) und Polycarbonat bei unterschiedlichen Temperaturen wurde eine Vorrichtung benutzt, die aus zwei Kammern besteht. Eine der Kammern enthält Wasser und in der anderen ist ein Feuchtigkeitssensor untergebracht. Die Kammern sind durch die Probe voneinander getrennt.Es konnte kein Unterschied zwischen der Permeation von flüssigem Wasser und der des Wasserdampfes festgestellt werden. Die Nachweisgenze des Messsystems für den Diffusionskoeffizienten liegt bei 7,98 · 10−13 m2/s. Für Polycarbonatfolien konnten der Diffusionskoeffizient, seine Temperaturabhängigkeit und die Aktivierungsenergie bestimmt werden. Diese Werte sind vergleichbar mit den Werten in der Literatur. In späteren Experimenten sollen Materialien mit verschiedenen Barriereschichten versehen werden, um die Permeation weiter zu verringern.
A framework for predicting and visualizing the East African wildebeest migration‐route patterns in variable climatic conditions using geographic information system and remote sensing
Authors: Musiega Douglas E. , Sanga‐Ngoie Kazadi , Fukuyama Kaoru 
Published: June 2006

AbstractIn the Serengeti–Mara ecosystem of East Africa, the migrating wildebeests’ (Connochaetes taurinus) response to food resource distribution and terrain complexity impacts their movement characteristics. This manifests in varying ways such as movement speed, direction, turning frequency, and moving distance. To investigate these characteristics, indices derived from vegetation quantity (normalized difference vegetation index, NDVI) and relief (slope) were used in our previous work to quantify the relationships between migration route location versus vegetation, relief complexity, and their combination. Least cost pathways determined using these indices were representative of approximate migration routes. The simulated routes were shown to be strongly influenced by vegetation during the dry season. However the impact of climatic change (rainfall) on route location was not investigated though known to influence vegetation recovery patterns. This paper specifically addresses the impact of climatic change on route location. The mean monthly rainfall data were used to classify the rainy and dry seasons in the Serengeti, the Western, and the Mara areas as normal, drier, or wetter than normal, over the 1986–1997 period. The classification is based on the mean monthly rainfall variability about the 11‐year seasonal mean. Regression analysis showed strong linear relationships between rainfall and mean NDVI for each one of the three areas. The subsequent seasonal classification based on the corresponding habitat vegetation characteristics (NDVI) revealed the relative variation of vegetation with rainfall. Using the derived general categories, migration routes are then predicted for the various categories using a “route attractivity index.” The seasonal migration routes were shown to change depending on the relative abundance of the rainfall during the dry season. Dry season migration routes tended toward areas with better vegetation activity, i.e., those characterized by higher NDVI gradients. Our results showed that during the western trek, wetter dry seasons have the effect of delaying the herds movement northwestward. During the northern trek, wetter dry seasons have the effect of delaying the tendency to move westward. However the variation in rainfall conditions during the rainy and dry season had no significant influence on the southern trek route location. We assume that predicted routes based on average general category conditions for different years are representative of main migration route patterns for similar seasons, therefore they are well suited for approximate route prediction, if the climatic characteristics of the year are known.
The effect of age on referral to and use of specialist palliative care services in adult cancer patients: a systematic review
Authors: Burt Jenni , Raine Rosalind 
Published: June 2006

Abstract
Objective: to investigate variations in the use of specialist palliative care (SPC) services for adult cancer patients, in relation to age.
Design: systematic review of studies examining use of or referral to SPC services in adult cancer patients.
Search strategy and selection criteria: six electronic databases (Medline, Embase, Web of Science, HMIC, SIGLE and AgeInfo) were searched for studies published between 1966 and March 2005, and references in the articles identified were also examined. Inclusion criteria were all studies which provided data on age in relation to use of or referral to SPC. Two reviewers independently selected studies, extracted data and assessed methodological quality according to defined criteria.
Main outcome measures: use of or referral to SPC services, determined from all sources of report (patient, informal carer, health care professional, health care records).
Results: 14 studies were identified. All reported a statistically significant lower use of SPC among older cancer patients (65 and above or older) at a univariate level [crude odds ratios ranged from 0.33 (0.15–0.72) to 0.82 (0.80–0.82)]. However, there were important methodological weaknesses in all of the studies identified; most crucially, studies failed to consider variations in use in relation to need for SPC.
Conclusions: there is some evidence that older people are less likely to be referred to, or to use, SPC. These findings require confirmation in studies using prospectively collected data which control for patient’s need for SPC.
Silencing the Flavonoid Pathway in Medicago truncatula Inhibits Root Nodule Formation and Prevents Auxin Transport Regulation by Rhizobia
Authors: Wasson Anton P. , Pellerone Flavia I. , Mathesius Ulrike 
Published: June 2006

Abstract
Legumes form symbioses with rhizobia, which initiate the development of a new plant organ, the nodule. Flavonoids have long been hypothesized to regulate nodule development through their action as auxin transport inhibitors, but genetic proof has been missing. To test this hypothesis, we used RNA interference to silence chalcone synthase (CHS), the enzyme that catalyzes the first committed step of the flavonoid pathway, in Medicago truncatula. Agrobacterium rhizogenes transformation was used to create hairy roots that showed strongly reduced CHS transcript levels and reduced levels of flavonoids in silenced roots. Flavonoid-deficient roots were unable to initiate nodules, even though normal root hair curling was observed. Nodule formation and flavonoid accumulation could be rescued by supplementation of plants with the precursor flavonoids naringenin and liquiritigenin. The flavonoid-deficient roots showed increased auxin transport compared with control roots. Inoculation with rhizobia reduced auxin transport in control roots after 24 h, similar to the action of the auxin transport inhibitor N-(1-naphthyl)phthalamic acid (NPA). Rhizobia were unable to reduce auxin transport in flavonoid-deficient roots, even though NPA inhibited auxin transport. Our results present genetic evidence that root flavonoids are necessary for nodule initiation in M. truncatula and suggest that they act as auxin transport regulators.
Cooperative α‐helix unfolding in a protein–DNA complex from hydrogen–deuterium exchange
Authors: Salinas Roberto K. , Diercks Tammo , Kaptein Robert , Boelens Rolf 
Published: June 2006

AbstractWe present experimental evidence for a cooperative unfolding transition of an α‐helix in the lac repressor headpiece bound to a symmetric variant of the lac operator, as inferred from hydrogen–deuterium (H–D) exchange experiments monitored by NMR spectroscopy. In the EX1 limit, observed exchange rates become pH‐independent and exclusively sensitive to local structure fluctuations that expose the amide proton HN to exchange. Close to this regime, we measured decay rates of individual backbone HN signals in D2O, and of their mutual HN–HN NOE by time‐resolved two‐dimensional (2D) NMR experiments. The data revealed correlated exchange at the center of the lac headpiece recognition helix, Val20–Val23, and suggested that the correlation breaks down at Val24, at the C terminus of the helix. A lower degree of correlation was observed for the exchange of Val9 and Ala10 at the center of helix 1, while no correlation was observed for Val38 and Glu39 at the center of helix 3. We conclude that HN exchange in the recognition helix and, to some extent, in helix 1 is a cooperative event involving the unfolding of these helices, whereas the HN exchange in helix 3 is dominated by random local structure fluctuations.
Structural analysis of an “open” form of PBP1B from Streptococcus pneumoniae
Authors: Lovering Andrew L. , De Castro Liza , Lim Daniel , Strynadka Natalie C.J. 
Published: June 2006

AbstractThe class A PBP1b from Streptococcus pneumoniae is responsible for glycosyltransferase and transpeptidase (TP) reactions, forming the peptidoglycan of the bacterial cell wall. The enzyme has been produced in a stable, soluble form and undergoes time‐dependent proteolysis to leave an intact TP domain. Crystals of this TP domain were obtained, diffracting to 2.2 Å resolution, and the structure was solved by using molecular replacement. Analysis of the structure revealed an “open” active site, with important conformational differences to the previously determined “closed” apoenzyme. The active‐site nucleophile, Ser460, is in an orientation that allows for acylation by β‐lactams. Consistent with the productive conformation of the conserved active‐site catalytic residues, adjacent loops show only minor deviation from those of known acyl‐enzyme structures. These findings are discussed in the context of enzyme functionality and the possible conformational sampling of PBP1b between active and inactive states.
Identification of cognate ligands for the Escherichia coli phnD protein product and engineering of a reagentless fluorescent biosensor for phosphonates
Authors: Rizk Shahir S. , Cuneo Matthew J. , Hellinga Homme W. 
Published: June 2006

AbstractThe Escherichia coli phnD gene is hypothesized to code for the periplasmic binding component of a phosphonate uptake system. Here we report the characterization of the phosphonate‐binding properties of the phnD protein product. We find that PhnD exhibits high affinity for 2‐aminoethylphosphonate (5 nM), the most commonly occurring natural phosphonate produced by lower eukaryotes, but also binds several other phosphonates with micromolar affinities. A significant number of man‐made phosphonates, such as insecticides and chemical warfare agents, are chemical threats and environmental pollutants. Consequently, there is an interest in developing methods for the detection and bioremediation of phosphonates. Bacterial periplasmic‐binding proteins have been utilized for developing reagentless biosensors that report analytes by coupling ligand‐binding events to changes in the emission properties of a covalently conjugated environmentally‐sensitive fluorophore. Several PhnD conjugates described here show large changes in fluorescence upon binding to methylphosphonate (MP), with two conjugates exhibiting up to 50% decrease in emission intensity. Since MP is the final degradation product of many nerve agents, these PhnD conjugates can function as components in a biosensor system for chemical warfare agents.
Dissociation of intermolecular disulfide bonds in P22 tailspike protein intermediates in the presence of SDS
Authors: Kim Junghwa , Robinson Anne Skaja 
Published: June 2006

AbstractEach chain of the native trimeric P22 tailspike protein has eight cysteines that are reduced and buried in its hydrophobic core. However, disulfide bonds have been observed in the folding pathway and they are believed to play a critical role in the registration of the three chains. Interestingly, in the presence of sodium dodecyl sulfate (SDS) only monomeric chains, rather than disulfide‐linked oligomers, have been observed from a mixture of folding intermediates. Here we show that when the oligomeric folding intermediates were separated from the monomer by native gel electrophoresis, the reduction of intermolecular disulfide bonds did not occur in the subsequent second‐dimension SDS–gel electrophoresis. This result suggests that when tailspike monomer is present in free solution with SDS, the partially unfolded tailspike monomer can facilitate the reduction of disulfide bonds in the tailspike oligomers.
Fluorescence resonance energy transfer study of subunit exchange in human lens crystallins and congenital cataract crystallin mutants
Authors: Liang Jack J. , Liu Bing‐Fen 
Published: June 2006

AbstractLens α‐crystallin is an oligomeric protein with a molecular mass of 500–1000 kDa and a polydispersed assembly. It consists of two types of subunits, αA and αB, each with a molecular mass of 20 kDa. The subunits also form homo‐oligomers in some other tissues and in vitro. Their quaternary structures, which are dynamic and characterized by subunit exchange, have been studied by many techniques, including fluorescence resonance energy transfer (FRET) and mass spectrometry analysis. The proposed mechanism of subunit exchange has been either by dissociation/association of monomeric subunits or by rapid equilibrium between oligomers and suboligomers. To explore the nature of subunit exchange further, we performed additional FRET measurements and analyses using a fluorescent dye‐labeled W9F αA‐crystallin as the acceptor probe and Trp in other crystallins (wild‐type and R116C αA, wild‐type and R120G αB, wild‐type and Q155* βB2) as the donor probe and calculated the transfer efficiency, Förster distance, and average distance between two probes. The results indicate only slight decreased efficiency and increased distance between two probes for the R116C αA and R120G αB mutations despite conformational changes.
SOME APPLICATIONS OF THE DRUM AND CABLE IN A BRICK PLANT
Authors: Twells Robert 
Published: June 2006

ABSTRACTApplication of the drum and cable in a brick plant, for plowing and scraping the shale, for transferring it to the driers and out again and for carrying the burned bricks to the freight cars are described. The devices are simple and cheap, but they have effected a great saving and have made it much easier to get the necessary labor.
A MERCURY VOLUMETER1
Authors: Goodner Ernest F. 
Published: June 2006

ABSTRACTA new volumeter using mercury as the liquid for determining volumes of solids.Existing volumeters.—The eight principal volumeters which have been in use during the past few years are discussed, the disadvantages and advantages being pointed out and the requisites of a satisfactory voltmeter are outlined.Description of new mercury voltmeter.—The volumeter consists of a burette which may be raised or lowered by means of a rack and pinion. To the lower end of the burette there is a rubber tube attached which connects at the other end with a reservoir. This reservoir is at a fixed point, level with the bottom of the burette when raised to its highest point and is partially filled with mercury. The whole volumeter is, in action, a large “U”‐tube with one movable limb (the burette). The volume is obtained by placing the briquette in the reservoir, causing a rise in the level of the mercury in both limbs of the “U”‐ tube. The burette is then lowered until the mercury has resumed its former level, this movement being the measure of the volume which is read directly from the graduations on the burette.Mathematical analysis.—It is shown that a ratio of 1:1 of the reservoir and burette areas of free mercury surface will enable the reading of volumes as accurately as one can obtain the burette reading.Comparative tests with other voltmeters.—Tests of the action of mercury, water and kerosene show that they behave alike in obtaining volumes. No saturation of burned or dry briquettes is necessary when using mercury as the liquid. Volumes with pycnometer and overflow types of volumeters checked those obtained with mercury volumeter to within 5/100 a cc.Per cent variation of readings.—Results of three operators working independently indicate that for volumes above 25.00 cc. the volumeter is consistent within 0.2 per cent which is also the accuracy of the result.Disadvantages.—1. The initial cost of about two pounds of mercury. 2. The slight tendency of the mercury to remain in cracks and holes of some briquettes, although readily shaken back into the reservoir. 3. A slight difficulty in obtaining the reading for the first dozen determinations.Advantages.—1. No 12‐hour soaking in kerosene is necessary for dry briquettes. 2. There is no draining of briquettes after immersion. 3. No draining of liquid is necessary. 4. It is direct reading. 5. It is very speedy and accurate. 6. No adjustment is necessary before each volume is taken, and, when adjustment is required, it is very quickly accomplished. 7. There is no adjusting of ground glass stoppers.