bluuebunny/crossref_metadata_2025 huggingface dataset:
Human iliac crest cancellous bone elastic modulus and hardness differ with bone formation rate per bone surface but not by existence of prevalent vertebral fracture
Authors: Wang Xiang , Sudhaker Rao D. , Ajdelsztajn Leonardo , Ciarelli Traci E. , Lavernia Enrique J. , Fyhrie David P.
Published: August 2007

The goals of this study were to measure tissue‐level elastic moduli and hardness of human cancellous bone using nanoindentation, and determine the relationship between nanoindentation results and previously measured bone histomorphometric variables and bone mineralization. Forty iliac crest biopsies were used in this study, which were collected from Caucasian females with vertebral fracture or from a normal healthy female Caucasian population. They were also categorized into two groups according to high or low bone formation rate per bone surface (BFR/BS). Thirty‐two sites were randomly selected on each specimen for nanoindentation with a Berkovich diamond indenter. Two sets of elastic moduli and hardness were calculated using the continuous stiffness measurement method and the Oliver–Pharr method, respectively. Relationships between nanoindentation results and donor age, bone mineralization, and histomorphometric variables were examined. No difference in elastic moduli or hardness was observed between the normal and fracture groups. Significantly lower elastic moduli were observed in the high BFR/BS group. The elastic moduli and hardness measurements were not significantly correlated with the bone mineralization measured independently in a previous study. Linear correlation between elastic modulus and hardness calculated using the Oliver–Pharr method was not different between the normal and fracture groups or between the high and low BFR/BS groups. Nanoindentation hardness was a very good predictor of bone tissue elastic modulus for both normal and osteoporotic bone tissues. Osteoporosis may not change the relationship between bone tissue elastic modulus, bone hardness, and bone mineralization. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
A bFGF/TCP‐composite inhibits bone formation in a sheep model
Authors: Maus Uwe , Andereya Stefan , Ohnsorge Jörg A. K. , Gravius Sascha , Siebert Christian H. , Niedhart Christopher
Published: August 2007

Basic fibroblast growth factor is a well known osteostimulative protein. The effects of basic fibroblast growth factor are dose‐dependent and, when used with a carrier, influenced by the release kinetics. Aim of our study was to determine the effects of a composite of basic fibroblast growth factor and a newly developed, in situ setting tricalcium phosphate (TCP) cement. A trepanation defect in the distal femoral epiphysis of Merino‐Mix sheep with a diameter of 9.4 mm and 10 mm depth was filled with the in situ setting TCP cement combined with 0 or 200 μg of bFGF/cm3 TCP, autologous bone graft or left empty. The sheep were euthanized after 3 months. The defect and the periimplant area were examined by microradiography, histology, and histomorphometry. The data was analyzed with the help of the Wilcoxon and Kruskal–Wallis tests. Defects filled with TCP with or without bFGF showed a close bone‐cement contact. The histomorphometric analysis revealed that the addition of bFGF inhibited the ingrowth of bone significantly, while the resorption of the cement was not influenced. In conclusion, the clinical application of this bFGF/TCP‐composite does not seem promising. The reason for the inhibition of new bone formation will be discussed, but requires further investigation. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Efficacy of ciprofloxacin implants in treating experimental osteomyelitis
Authors: Alvarez H. , Castro C. , Moujir L. , Perera A. , Delgado A. , Soriano I. , Évora C. , Sánchez E.
Published: August 2007

Ciprofloxacin (CFX) implants containing poly(D,L‐lactide) and calcium phosphates (tricalcium phosphate and hydroxyapatite) was evaluated in 50 rabbits in an experimental osteomyelitis model. Their femoral cavity was inoculated with Staphylococcus aureus. After 2 weeks, the infected focus was cleaned out and the delivery system implanted. The infection and subsequent response to treatment were evaluated by microbiological analysis, biochemical and hematological markers, body weight, temperature, clinical signs, X‐rays, and histology. Infected bone cultures, treated with CFX implants, showed reduced bacterial growth against controls. All CFX was released within 6 weeks. All animals recovered within 4 weeks. Even 12 weeks after implantation, no recurrence of infection was observed. Serum C‐reactive protein, platelet, and leukocyte levels increased in all animals before treatment, and 4 weeks after it were maintained or rose in control animals, while decreased to normal levels in treated ones. Body weight was characterized by pretreatment losses, then gains during recuperation, or further loss in untreated animals; with no significant intraindividual differences in body temperature. Body weight, leucocytes, platelets, and C‐reactive protein turned out to be highly useful markers for monitoring this kind of infection and its treatment. CFX implants demonstrated to be an effective therapy for S. aureus bone infection. Their efficacy was also reflected in decreasing severity of clinical signs, nonprogress of radiological signs indicative of infection, and good integration into bone structure. Histological examination revealed repair, with new bone formation extending into implants. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Molecular phylogeny of the three paedomorphic mediterranean gobies (Perciformes: Gobiidae)
Authors: Giovannotti Massimo , Cerioni Paola Nisi , La Mesa Mario , Caputo Vincenzo
Published: August 2007

Pelagic gobies are considered of particular zoological interest because the acquisition of a pelagic lifestyle is achieved through the persistence of larval anatomical features. The Mediterranean Sea is inhabited by three goby species (Aphia minuta, Crystallogobius linearis and Pseudaphya ferreri) characterized by paedomorphic traits. Owing to the shared larval morphological features, these species have generally been considered as a monophyletic group. This study aimed at establishing the phylogenetic relationships of these paedomorphic species within the family Gobiidae to ascertain whether the pelagic lifestyle achieved through paedomorphosis is due to an event that took place in a common ancestor or not. For this purpose, we amplified by polymerase chain reaction and sequenced the mitochondrial 12S rDNA (complete sequence) and 16S rDNA (partial sequence) of 15 Mediterranean gobies. The phylogenetic analysis strongly supported the polyphyletic origin of the three paedomorphic gobies, indicating that the heterochronic change leading to the retention of larval features seems to have occurred independently in the ancestors of these species. Thus, the sharing of morphological traits can be considered homoplasious and the classification of these species in the same taxonomic group is rejected on the basis of molecular data. J. Exp. Zool. (Mol. Dev. Evol.) 308B:722–729, 2007. © 2007 Wiley‐Liss, Inc.
Vertex disjoint equivalent subgraphs of order 3
Authors: Nakamigawa Tomoki
Published: August 2007

Let k be a fixed integer at least 3. It is proved that every graph of order (2k − 1 − 1/k)n + O(1) contains n vertex disjoint induced subgraphs of order k such
that these subgraphs are equivalent to each other and they are equivalent to one of four graphs: a clique, an independent set, a star, or the complement of a star. In particular, by substituting 3 for k, it is proved that every graph of order 14n/3 + O(1) contains n vertex disjoint induced subgraphs of order 3 such that they are equivalent to each other. © 2007 Wiley Periodicals, Inc. J Graph Theory 56: 159–166, 2007
Examination of hospital referral practices for CT pulmonary angiography
Authors: Kiley Cristin A. , Lowry Kristie J. , Mysliwiec Vincent
Published: August 2007

Guidelines for the evaluation of venous thromboembolism (VTE) include a history and physical examination in conjunction with computed tomographic pulmonary angiography (CTPA), Doppler ultrasonography, and D‐dimer measurements. We performed a retrospective analysis to evaluate the diagnostic yield of CTPA at our facility. Patients between the ages of 18 and100 with a CTPA completed through the emergency department and/or any inpatient service over a 6‐month period were reviewed and a retrospective Simplified Wells Score was calculated. Three hundred and three patients underwent CTPA for acute VTE. A Simplified Wells Score was calculated for 279 subjects, with a mean score of 1.6 ± 1.6. Twenty CTPA procedures demonstrated VTE, a positive rate of 7.2%, which was lower than expected. This result likely reflects lack of adherence to a clinical algorithm for assessment of VTE and an overly cautious approach to symptom evaluation. Journal of Hospital Medicine 2007;2:253–257. © 2007 Society of Hospital Medicine.
The impact of climate variability on soybean yields in Argentina. Multivariate regression
Authors: Penalba Olga C. , Bettolli M. Laura , Vargas Walter M.
Published: August 2007

Climate variability is examined and discussed in this work, emphasizing its influence over the fluctuation of soybean yield in the Pampas (central‐eastern Argentina). Monthly data of rainfall, maximum and minimum temperatures, thermal range and seasonal rainfall were analysed jointly with the soybean yield in the period 1973‐2000. Low‐frequency variability was significant only in the minimum temperature during November in almost all the stations. This situation is favourable to the crop since during this month, seed germination, a growth stage sensitive to low temperatures, takes place. In the crop's core production region, 72% of the series of soybean yield presented a positive trend. Except in years with extreme rainfall situations, interannual variability of the soybean yield is in phase with the seasonal rainfall interannual variability. During these years, losses in the soybean crop occurred, with yield negative anomalies greater than one standard deviation. Soybean yield showed spatial coherence at the local scale, except in the crop's core zone. The association between each climate variable and yield did not show a defined regional pattern. Summer high temperature and rainfall excesses during the period of maturity and harvest have the greatest negative impact on the crop, whilst higher minimum temperatures during the growing season favour high yields. The joint effect of climate variables over yield was studied with multivariate statistical models, assuming that the effect of other factors (such as soil, technology, pests) is contained in the residuals. The regression models represent the estimates of the yield satisfactorily (high percentage of explained variance) and can be used to assess expected anomalies of mean soybean yield for a particular year. However, the predictor variables of the yield depend on the region. Copyright © 2007 Royal Meteorological Society
A high‐resolution radar experiment on the island of Jersey
Authors: Rico‐Ramirez M. A. , Cluckie I. D. , Shepherd G. , Pallot A.
Published: August 2007

A very high‐resolution X‐band vertically pointing weather radar was deployed in the island of Jersey, UK, from February to May 2004, to study the variation of the vertical reflectivity of precipitation (VPR) in this region. Intercomparison studies were carried out with a C‐band scanning weather radar operated by Jersey Met. Department. C‐band radar rainfall estimations and raingauge measurements were well correlated at very short ranges (<10 km), but there are clear difficulties in the estimation of precipitation due to ground clutter, and anomalous propagation echoes as well as the variation of VPR. Average VPRs were obtained from the X‐band radar that helped reduce the bright band enhancement in C‐band scanning weather radar measurements. This paper presents the overall results obtained during this radar experiment. The experiment was one of a series designed to understand the VPR and design removal algorithms for bright band contamination of quantitative radar measurements of precipitation. Copyright © 2007 Royal Meteorological Society
The influence of an upper‐level frontal zone on the Mack Lake Wildfire environment
Authors: Zimet Tarisa , Martin Jonathan E. , Potter Brian E.
Published: August 2007

Meteorological assessment of wildland fire danger has traditionally involved the identification of several synoptic weather types empirically determined to influence wildfire spread. Specifically, in the Great Lakes Region, high wildfire danger is often witnessed in association with northwesterly synoptic‐scale flow aloft. Such synoptic‐scale flow is regularly associated with the development of upper‐level frontal zones also known as upper‐level jet/front systems, which are often characterised by intrusions of stratospheric air into the troposphere. The notion that upper‐frontal development can play an important role in promoting wildfire spread is advanced through interrogation of the output from a fine‐scale numerical simulation of a documented explosive wildfire case; the Mack Lake Fire of May 1980.

The Mack Lake case was characterised by a developing upper‐level front embedded within a shortwave trough in the vicinity of the fire location. The upper‐level front originated in northwesterly flow in central Canada as an upper‐tropospheric ridge amplified over western North America. A thermally indirect circulation at the jet exit region both contributed to the intensification of the front and was associated with a maximum in quasi‐geostrophic descent at mid‐levels upstream of the fire region. The subsidence ushered dry air from the middle and upper‐troposphere downward along sloping isentropes adiabatically warming and drying it along the way. A well‐developed dry air intrusion associated with the operation of these processes extended to nearly the 750 hPa level far downstream from the actual upper‐frontal zone supplying the fire environment with dry air that originated in the upper‐troposphere/lower stratosphere. The organised subsidence was also responsible for downward advection of high momentum air from within the frontal zone into the fire environment, further influencing the wildfire spread. We conclude that upper‐frontal processes, characteristic of northwesterly synoptic‐scale flow, are likely a contributing factor to the prevalence of wildfire spread under such synoptic‐scale conditions. Copyright © 2007 Royal Meteorological Society
Modelling the impact of high‐rise buildings in urban areas on precipitation initiation
Authors: Carraça M. G. D. , Collier C. G.
Published: August 2007

The impact of urban areas upon precipitation distribution has been studied for many years. However, the relative importance of the distribution and type of surface morphology and urban heating remains unclear.

A simple model of the surface sensible heat flux is used to explore the impact of urban heterogeneity. Sensitivity experiments are carried out to test the validity of the model, and experiments with a schematic urban morphology are used to investigate the impact of different types of building arrays. It is found that high‐rise buildings over relatively small areas may have just as much impact as somewhat lower buildings covering a much larger area. The urban area produces considerable spatial variation in surface sensible heat flux. Data from a C‐band radar located to the north of Greater Manchester provides evidence that convective cells may be initiated by the sensible heat flux input generated by the high‐rise buildings in the city centre when the atmospheric boundary layer is unstable. Copyright © 2007 Royal Meteorological Society
Assessment of some spatial climatic layers through GIS and statistical analysis techniques in Samsun Turkey
Authors: Guler Mustafa , Cemek Bilal , Gunal Hikmet
Published: August 2007

An empirical methodology in modelling and mapping air temperatures (monthly minimum, mean and maximum), monthly relative humidities and cumulative precipitation using geographical information system (GIS) techniques was proposed. Linear regression analyses were developed between weather data and some of the geographical and climatical variables (altitude, monthly mean temperature and relative humidity) of the study area. Data were obtained from 11 different meteorological stations located in the study area, and elaborated from a 250 m resolution digital elevation model (DEM). Analyses of digital layers of each independent variable with basic GIS techniques were used, and the most suitable models obtained from regression analysis were used to create final maps. The coefficients of determination for monthly mean and minimum temperatures were 0.68 and 0.98, respectively. In the case of monthly relative humidity, r2 ranged between 0.80 and 0.98, while in the case of monthly cumulative precipitation, it ranged from 0.82 to 0.98, respectively. Maximum monthly temperature, particularly for the summer months had a low relationship with elevation, therefore determination coefficient ranged from 0.46 to 0.81. When spatial information is available, the proposed method could be used as an alternative to classical interpolation techniques. Copyright © 2007 Royal Meteorological Society
Forecasting of thunderstorms in the pre‐monsoon season at Delhi
Authors: Ravi N , Mohanty U C , Madan O P , Paliwal R K
Published: August 2007

Accurate prediction of thunderstorms during the pre‐monsoon season (April–June) in India is essential for human activities such as construction, aviation and agriculture. Two objective forecasting methods are developed using data from May and June for 1985–89. The developed methods are tested with independent data sets of the recent years, namely May and June for the years 1994 and 1995. The first method is based on a graphical technique. Fifteen different types of stability index are used in combinations of different pairs. It is found that Showalter index versus Totals total index and Jefferson's modified index versus George index can cluster cases of occurrence of thunderstorms mixed with a few cases of non‐occurrence along a zone. The zones are demarcated and further sub‐zones are created for clarity. The probability of occurrence/non‐occurrence of thunderstorms in each sub‐zone is then calculated. The second approach uses a multiple regression method to predict the occurrence/nonoccurrence of thunderstorms. A total of 274 potential predictors are subjected to stepwise screening and nine significant predictors are selected to formulate a multiple regression equation that gives the forecast in probabilistic terms. Out of the two methods tested, it is found that the multiple regression method gives consistently better results with developmental as well as independent data sets; it is a potential method for operational use. Copyright © 1999 Royal Meteorological Society
Spatial interpolation of GPS integrated water vapour measurements made in the Swiss Alps
Authors: Morland June , Mätzler Christian
Published: August 2007

The 31 stations in the Swiss GPS network are located at altitudes between 330 and 3584 m and have provided hourly Integrated Water Vapour (IWV) measurements since November 2000. A correction based on an exponential relationship is proposed for the decrease in IWV with altitude. The scale height depends on the ratio of IWV measured at Jungfraujoch (3584 m) to that measured at Payerne (498 m). An additional coefficient, dependent on the east‐west and north‐south spatial differences in the IWV, improves the fit to the data. The IWV at heights between 750 and 3500 m was estimated from GPS measurements at Payerne and compared with the Payerne radiosounding. The altitude correction introduced an additional bias of 0.2 to 0.4 mm between GPS and radiosonde. The IWV was normalized to 500 m and the increases and decreases due to the passage of a series of frontal systems between 11 and 14 January 2004 were mapped. A four‐year climatology of IWV normalized to 500 m showed that the Alpine stations are more moist in spring, summer and autumn than the stations in the Swiss plains to the north of the Alps. This was attributed to more moist Mediterranean air being blocked by the Alps. Copyright © 2007 Royal Meteorological Society
Bias adjustment and long‐term verification of radar‐based precipitation estimates
Authors: Holleman Iwan
Published: August 2007

Quantitative precipitation estimates (QPE) based on weather radar observations are used more and more for water management, in numerical weather prediction models, and for monitoring of severe weather. A straightforward method for bias adjustment of radar‐based and hourly‐updated precipitation accumulations is described. In addition a long‐term verification of the bias‐adjusted composites over a six year period using dependent and independent gauge data is presented. It is found that the adjustment scheme effectively removes the mean‐field bias from the raw accumulations. The adjustment method cannot correct for a range‐dependent bias and therefore it is recommended to also use a simple vertical profile of reflectivity (VPR) adjustment procedure. Copyright © 2007 Royal Meteorological Society
Comparison of VAAC atmospheric dispersion models using the 1 November 2004 Grimsvötn eruption
Authors: Witham C. S. , Hort M. C. , Potts R. , Servranckx R. , Husson P. , Bonnardot F.
Published: August 2007

The robustness of the Numerical Atmospheric‐dispersion Modelling Environment (NAME) for forecasting the dispersion of volcanic ash clouds is investigated by comparing the output from different Volcanic Ash Advisory Centre (VAAC) models initialised using the parameters for the 2004 Grimsvötn, Iceland, volcanic eruption. London, Darwin, Washington, Montreal and Toulouse VAAC dispersion models are all run operationally as if responding to the eruption. Comparison of the model set‐ups reveals differing approaches between the VAACs for model averaging times, ash release rates, and thresholds for defining the ash cloud, amongst others. The importance of these factors is considered in detail. Despite using different weather conditions and having different structures, the models all demonstrate strong similarities for forecasting regional ash cloud transport. The dispersal of volcanic ash is simulated over Scandinavia and as far as Eastern Europe in all cases. Greater variations are seen between the forecast ash concentrations for different aircraft flight levels. The model forecasts are highly dependent on the amount of eruption information available at the time. Copyright © 2007 Royal Meteorological Society
Weather conditions associated with the potential for pollen recirculation in a coastal area
Authors: Gassmann María Isabel , Gardiol Jesús María
Published: August 2007

This study aims to characterise the main synoptic field patterns associated with the potential for recirculation of pollen. A recirculation index (R) was calculated in the area of Mar del Plata, Argentina. The daily development of sea–land breeze and the related monthly frequencies of wind directions were studied. The sea breeze was present for 36.2% of the time, with a mean lifetime of about 2 h in winter and 15–20 h in summer. Recirculation of the air had an annual frequency of around 7%, with a net transport from the city outskirts towards the sea, for 39.4% of the year, and a net inland transport frequency of 38.4%. The Rotated Principal Component Analysis (PCA) was applied to obtain synoptic field patterns associated with potential conditions for recirculation in the area. It was shown that low‐pressure systems or troughs between 45° and 60°S (i.e. over the country, the South Pacific and/or the South Atlantic and two anticyclones located in the Atlantic or South Pacific Oceans) are the most common weather conditions associated with air recirculation in the coastal area of Buenos Aires province. A case study with high night pollen concentrations was also analysed. Copyright © 2007 Royal Meteorological Society
The development of a rating scale to screen social and emotional detachment in children and adolescents
Authors: Scholte E. M. , van der Ploeg J. D.
Published: August 2007

Rating scales to assess psychopathic characteristics in children and adolescents show a considerable item overlap with rating scales to assess attention deficit hyperactivity disorder (ADHD), oppositional‐defiant disorder (ODD) and conduct disorder (CD) symptoms. The aim of this study is to preliminary test a short questionnaire clinicians can use to screen the unique characteristics of psychopathy. Parental ratings of psychopathic characteristics and symptoms of ADHD, ODD and CD were gathered in a community sample of 2535 4–18‐year‐old Dutch children. The dimensionality of the ratings was determined by factor analysis and related to ADHD, ODD and CD. Two factors emerged covering egocentric‐narcissistic and callous‐unemotional characteristics. To avoid unnecessary stigmatization of youngsters the first factor is referred to as the “social detachment dimension” and the second as the “emotional detachment dimension”. Parental ratings were reliable across all age and gender groups, and correlated moderately with ODD and CD, but not with ADHD. Preliminary findings support a two‐dimensional syndrome depicting respectively narcissistic and unemotional characteristics. The syndrome is associated with ODD and CD symptoms and possibly depicts a subtype of the ODD/CD childhood disorder. Copyright © 2007 John Wiley & Sons, Ltd.
Catalase overexpression does not impair extensor digitorum longus muscle function in normal mice
Authors: Liu Mingju , Yue Yongping , Li Dejia , Duan Dongsheng
Published: August 2007

Catalase is a major antioxidant enzyme. Increasing catalase expression represents a promising avenue to improve muscle function in certain physiological conditions and in some muscle diseases. We hypothesized that catalase overexpression should not impair normal muscle contraction. We delivered a hemagglutinin (HA)‐tagged human catalase gene to normal mouse muscle by an adeno‐associated viral vector (AAV). Western blot and immunostaining revealed efficient expression of HA‐tagged catalase. Enzymatic assay demonstrated an approximately threefold increase in catalase activity in AAV‐infected muscles. Catalase overexpression impaired neither twitch nor tetanic tension in the extensor digitorum longus (EDL) muscle. Furthermore, EDL fatigue response was not altered. Taken together, we have developed a novel AAV vector to enhance catalase expression. Lack of apparent toxicity in normal muscle strongly supports further exploration of this vector to reduce oxidative stress–induced muscle damage. Muscle Nerve, 2007
Dynamic magnetic resonance imaging for grading pelvic organ prolapse according to the international continence society classification: Which line should be used?
Authors: Fauconnier Arnaud , Zareski Elise , Abichedid Joseph , Bader Georges , Falissard Bruno , Fritel Xavier
Published: August 2007

Aims

To assess and compare the reliability of dynamic MRI to quantify pelvic organ prolapse (POP) according to the International Continence Society (ICS) using two different reference lines, and to determine which line gives the best concordance with clinical examination.

Methods

Forty‐seven patients with genital prolapse underwent physical examination and dynamic MRI. Five nulliparous, symptom‐free female volunteers underwent dynamic MRI as control subjects. Two distinct observers performed the MRI measurements of POP according to the ICS using two distinct reference lines: the mid‐pubic line and a new one, the perineal line that provides a better match with the hymen plane. Measurements were repeated twice according to each line. The intra‐class coefficient was used to estimate intra‐observer and inter‐observer reliability; the Altman and Bland plot was used to assess the agreement between MRI and clinical measurements.

Results

The intra‐observer and inter‐observer reliability of MRI measurements were in general excellent. Intra‐class coefficients were better for the mid‐pubic line than the perineal line. Although the MRI measurements correlate significantly with the physical measurements, the Altman and Bland plot shows an unacceptable magnitude of discrepancy between clinical and MRI examinations.

Conclusions

Although dynamic MRI shows excellent inter‐ and intra‐observer reliability, its agreement with clinical examination is poor whatever the line used. Neurourol. Urodynam. 27:191–197, 2008. © 2007 Wiley‐Liss, Inc.
Demonstration of intrinsic innervation of the guinea pig upper urinary tract using whole‐mount preparation
Authors: Rolle Udo , Brylla Elke , Tillig Bernd , Chertin Boris , Cascio Salvatore , Puri Prem
Published: August 2007

Aims

The morphology and functional importance of the autonomic nervous system in the upper urinary tract is still not completely understood. Previous histological studies investigating the innervation of the urinary tract have mainly used conventional sections in which the three‐dimensional structure of the intramural innervation is difficult to achieve. In contrast, the whole‐mount preparation technique is a suitable method for visualizing the distribution of the mesh‐like neuronal networks within the urinary tract.

Methods

The distribution and regional variation of neurofilament (NF), tyrosine hydroxylase (TH), choline acetyltransferase (ChAT), and substance P‐immunoreactive (SP‐IR) neurons, as well as acetylcholinesterase (AChE) and nicotinamide adenine dinucleotide phosphate‐diaphorase (NADPH‐d)‐positive neurons were investigated using whole‐mount preparations of the guinea pig upper urinary tract.

Results

Two distinct nervous plexuses were detected within the muscle layers containing NF, TH, ChAT, and SP‐IR nerves. AChE‐positive nerves were seen in all layers. Only moderate NADPH‐d‐positive innervation was found. Renal pelvis, upper and lower part of the ureter showed an overall increased innervation compared to the middle portion of the ureter. Ganglia were found at the pelviureteric border displaying NF and TH immunoreactivity.

Conclusion

The whole‐mount preparation technique provides an elegant method for assessing the three‐dimensional architecture of ureteral innervation. The guinea pig upper urinary tract is richly supplied with adrenergic, cholinergic, nitrergic, and sensory nerves which suggest that the autonomous nervous system plays an important role in controlling ureteral motility and blood flow. Neurourol. Urodynam. 27:341–347, 2008. © 2007 Wiley‐Liss, Inc.
A numerical study of the accuracy and stability of symmetric and asymmetric RBF collocation methods for hyperbolic PDEs
Authors: Sarra Scott A.
Published: August 2007

Differentiation matrices associated with radial basis function (RBF) collocation methods often have eigenvalues with positive real parts of significant magnitude. This prevents the use of the methods for time‐dependent problems, particulary if explicit time integration schemes are employed. In this work, accuracy and eigenvalue stability of symmetric and asymmetric RBF collocation methods are numerically explored for some model hyperbolic initial boundary value problems in one and two dimensions. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2008
Relief device sizing for ethylene decompositions—high pressure polyethylene industry
Authors: Shannon David I
Published: August 2007

This paper discusses revisions to a method previously used for sizing relief devices (rupture disks) for vessels in high pressure polyethylene processes. The Re‐evaluation was forced by an unexpectedly high peak pressure in a product separator (high pressure separator, HPS) when an ethylene decomposition occurred. A method, based on revised equations for calculating the rate of pressure rise, is presented for determining relief requirements for ethylene decomposition in a confined space. The method applies to both HPSs and polyethylene autoclave reactors. Causes of decompositions and effect of comonomers are also discussed. Simulations for other events at different operating conditions, not shown, indicate a good match for peak pressures. Therefore, the described equations provide a good estimate of ethylene decomposition peak pressures given the initial conditions.

Although these methods were derived specifically for ethylene decompositions, the methods could be used for other decompositions. © 2007 American Institute of Chemical Engineers Process Saf Prog 2007
Lessons learned and mitigation options for hurricanes
Authors: (Bob) Bailey James R. , Levitan Marc L.
Published: August 2007

The 2005 hurricane season caused unprecedented levels of damage to coastal communities throughout the Gulf of Mexico. Hurricane Katrina and Hurricane Rita were of particular interest to petrochemical and refining companies, given the impacts they had to their onshore operations. Floodwaters and extreme winds from these two hurricanes damaged numerous types of assets, including tanks, cooling towers, generator buildings, process towers, pumps, controllers, utility poles, and transformers. They also caused prolonged power outages, supply disruptions, and widespread employee dislocations, all major contributors to both property and business interruption losses.

This paper will focus on the nature of wind damages sustained by these two events; the history of the design of these facilities in the context of current practices; the likelihood of such events occurring during the operating life of a plant; and options for mitigating future damage. Also discussed are ways to quantify risks in a manner that will enable operators and owners to make informed, cost‐effective decisions regarding mitigation planning and associated reductions in loss exposures. © 2007 American Institute of Chemical Engineers Process Saf Prog 2007
Defects in yttria‐stabilised zirconia: a positron annihilation study
Authors: Cizek J. , Melikhova O. , Kuriplach J. , Prochazka I. , Konstantinova T. E. , Danilenko I. A.
Published: August 2007

High‐resolution positron lifetime and coincidence Doppler‐broadening measurements on the yttria‐stabilised zirconia compacted nanopowders, differing in phase, stabiliser content and preparation conditions, are reported. The nature of defects observed in these materials is discussed on the basis of available experimental data and their comparison with theoretical calculations. It is concluded that positrons annihilate mainly in vacancy‐like defects at grain boundaries and in larger open‐volume defects associated with triple points. A fraction of positrons annihilating in mesopores of ≈ 2.5 nm diameter was also detected. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Irradiated polymethylmethacrylate studied by positron annihilation spectroscopy
Authors: Mohamed Hamdy F. M. , Abdel‐Hady E. E. , Mohamed Salwa S.
Published: August 2007

The effect of gamma irradiation dose on microscopic structure of polymethylmethacrylate (PMMA) has been studied using positron annihilation lifetime (PAL) and Doppler broadening of annihilation radiation (DBAR) techniques. The measurements were performed at room temperature as a function of the γ‐irradiation doses from 60‐1200 kGy. The observed lifetime spectra were resolved into three components. The size and the fraction of the o‐Ps hole volume were estimated from the positron annihilation parameters. The effect of γ‐irradiation was identified at lower doses to be cross‐linking while at higher doses the chemical degradation of the polymer was observed. Moreover, the distribution of the free volume shifts from a large to small size as the irradiation increases and has very similar Gaussian‐like distribution. The PAL results were confirmed with X‐ray measurement. A correlation between the macroscopic mechanical properties Hv and positron annihilation parameters has been demonstrated. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Gamma irradiation effects on polymethyl methacrylate
Authors: Al‐Qaradawi I. Y. , Abdulmalik D. A. , Madi N. K. , Almaadeed M.
Published: August 2007

The effect of gamma‐irradiation on the structure of polymethyl methacrylate (PMMA) has been investigated. In this study, the PMMA specimens were gamma‐irradiated at doses in the range of 0‐1000 kGy and measured by means of positron annihilation lifetime (PAL) spectroscopy. Irradiation dose dependence of the longest lifetime component (τ3), attributed to ortho‐positronium (o‐Ps) decay, and the intensity of this component (I3) was studied by positron annihilation lifetime spectroscopy (PAL). The two physical quantities were correlated with the size and density of free volume sites in the examined specimens and were compared with the thermal transitions in the material obtained using the DSC technique. It was found that the size and amount of free volume decreases with increasing dose due to irradiation‐enhanced crosslinking. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structure and free volume properties of semi‐crystalline poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) by positron annihilation lifetime analysis
Authors: Cheng Mei‐Ling , Sun Yi‐Ming
Published: August 2007

The effect of thermal history on the structure and free volume of bacterial poly(3‐hydroxybutyrate‐co‐5mol%‐3‐hydroxyvalerate) (PHBV5) membranes, prepared by the compression‐molding method, was investigated. Free volume size, number of free volume holes, and the distribution of free volume in slow‐, rapid‐, and step‐cooled semi‐crystalline PHBV5 membranes were measured by using positron annihilation lifetime spectroscopy (PALS). The lifetime spectra are resolved into four components and the corresponding annihilation mechanisms are addressed. The size of the free volume in the amorphous phase and the lamellar thickness and crystallite size in the crystalline phase of the slow‐cooled membrane were the largest among all kinds of membranes. The results suggest that the crystallization process not only affects the crystalline structure but also has impact on the free volume properties in amorphous phase of the polymers. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Study on polymer electrolyte membrane for fuel cells by using AMOC technique
Authors: Honda Yoshihide , Shibahara Yuji , Akiyama Yoko , Kimura Norio , Isoyama Goro , Tagawa Seiichi , Takeda Shin‐ichi , Izumi Yoshinobu , Nishijima Shigehiro
Published: August 2007

The proton conductivity in Polymer Electrolyte Membrane in Fuel Cells (PEMFC) is affected by the size of free spaces and hydrogen bond at the hydrophilic group. These parameters are influenced by the environmental conditions. We tried to correlate annihilation process of positron and proton conductivity by using Age‐Momentum Correlation (AMOC) measurement. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Applications of positron annihilation to polyamide membranes
Authors: Chen Hongmin , Liu Guang , Chakka Lakshmi , Huang Shu‐Hsien , Lee Kueir‐Rarn , Lai Juin‐Yih , Sun Yi‐Ming , Cheng Mei‐Ling , Jean Y. C.
Published: August 2007

Positron annihilation spectroscopy (PAS) has been used to study the depth profile (0 ‐ 8 µm) in a membrane system containing a thin layer of polyamide prepared by the interfacial polymerization of triethylenetetraamine (TETA) and trimesoyl chloride (TMC) onto the surface of asymmetric polyacrylnitrile (PAN). Doppler broadening S parameters of annihilation radiation energy spectra show a systematic variation with the doping time of TETA in the membrane preparation process of interfacial polymerization. The layer structures of composite membrane are obtained. A similar variation between S parameters with respect to TETA doping time and permeability but an anti‐correlation between S parameter and selectivity are observed. Future applications of PAS and slow positron beam to membrane technology appear to be promising. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Compression deformed UHMW polyethylene investigated by PALS and WAXS
Authors: Ortega Y. , Monge M. A. , Pareja R.
Published: August 2007

Positron lifetime and wide‐angle X‐ray scattering measurements have been performed on ultra high molecular weight polyethylene deformed in uniaxial compression. No changes in the fraction of positronium states have been detected, suggesting that the fraction of free volume remains constant during deformation under the present conditions. The PALS results reveals that compressive deformation under the present conditions does not produced voiding or free volume increase in the amorphous phase of semicrystalline UHMW‐PE. This is opposed to the result found in the tensile deformed material. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Positron lifetime studies on the free volume changes during deformation of rubber‐carbon black composites
Authors: Jobando V. O. , Quarles C. A.
Published: August 2007

The free volume behavior as a function of strain during deformation of natural rubber‐carbon black composites studied by positron annihilation lifetime spectroscopy (PALS) is reported. The lifetime and intensity of the ortho‐positronium (o‐Ps) pick‐off annihilation, which correlate with the average size and the number of holes respectively, were measured as a function of strain. The results show how PALS can detect the changes that occur in polymer composites samples and help explain the effect of carbon black on the properties of the composites when they are deformed under compression. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural heterogeneity in glassy polymeric materials revealed by positron annihilation and other supplementary techniques
Authors: Shantarovich V. P. , Suzuki T. , Ito Y. , Kondo K. , Yu R. S. , Budd P. M. , Yampolskii Yu. P. , Berdonosov S. S. , Eliseev A. A.
Published: August 2007

A disagreement between effective sizes of elementary free volumes found from the four component PATFIT analyses of positronium annihilation lifetime spectra and experiments on low temperature sorption for two membrane materials of internal microporosity poly(tri‐methyl‐silyl‐propyne) PTMSP and spiro‐linked benzodioxane polymer PIM‐1 is described and discussed. This disagreement can be minimized essentially using the fifth lifetime component but not the Gaussian distribution of the fourth component. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of MMT content on the microstructure and miscibility for PU/EP IPN nanocomposites by positron
Authors: Zhu Yuchan , Zhou Wei , Wang Junjun , Wang Bo , Kong Lingmei , Jia Qingming
Published: August 2007

Effects of montmorillonite (MMT) content on the free volume hole and miscibility were first investigated for polyurethane/epoxy resin (PU/EP) interpenetrating polymer network (IPN) nanocomposites by positron annihilation lifetime spectroscopy (PALS), X‐ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). An exfoliated (IPN/MMT1), a coexistence of exfoliated and intercalated (IPN/MMT3), and an intercalated (IPN/MMT5) structures were confirmed by XRD. Influences of two kinds of hydrogen bonding interactions including both between carbonyl group and N‐H group, and the other between urethane group and silicate layers have been discussed. PALS results reveal that the size of the free volume holes decreases after the MMT loaded due to the increase of chain packing efficiency. The large difference between IPN/MMT1 and IPN/MMT5 in the free volume distribution was observed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Detection of bicontinuous phase in some reverse micellar systems by positron lifetime spectroscopy
Authors: Yadav Ramesh , Chandramani Singh K. , Choudhary S. R. , Jain P. C.
Published: August 2007

Positron lifetime measurements have been made in some reverse micellar systems of cetyl tri methyl ammonium bromide (CTAB)/hexanol and tetra‐decyl‐tri‐methyl‐ ammonium‐bromide (TTAB)/pentanol by adding increasing amount of water in each system. For both the systems, the dependence of positron lifetime parameters on water concentration indicates the existence of bicontinuous phase in so called single reverse micellar phase. The results of this investigation have been presented in this paper. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Studying conductive polymer coating (BAM‐PPV) using positron annihilation spectroscopy
Authors: Zhang Renwu , Johnson Paul M. , Deluca Ryan J. , Alger Terry D. , Xu Jun , Suzuki R. , Ohdaira T. , Jean Y. C.
Published: August 2007

Positron annihilation spectroscopy has been used to study two conductive polymer coatings, Al‐507A and Al‐507B, consisting of BAM‐PPV (poly (bis‐dialkylamino) phenylene vinylene) dissolved in two different solvents, THF at 0.2% concentration and xylene at 1.0% concentration, respectively. These samples were sprayed on aluminum substrates. They were further subjected to neutral salt treatment for 240 hours for the corrosion test. Doppler broadening of annihilation radiation (DBAR) and positron annihilation lifetime spectroscopy (PALS) were employed to investigate the corrosion effect on the two coatings in addition to their free volume. It was found that there are two layers in the polymer topcoat of sample Al‐507A while they were not clearly seen in Al‐507B. Interestingly the near‐surface layer demonstrates a large change after the salt treatment, suggesting creation of extra free volume. Both DBAR and PALS measurements indicate that the amount of free volume for Al‐507B coating is more than that for Al‐507A coating, while the free‐volume hole size for both coatings are similar, around 0.32 nm. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Positron annihilation in three zirconia polymorphs
Authors: Melikhova O. , Kuriplach J. , Čížek J. , Procházka I. , Anwand W. , Brauer G. , Konstantinova T. E. , Danilenko I. A.
Published: August 2007

Positron lifetimes and high momentum profiles both for the perfect lattice and selected defects are calculated in three (cubic, tetragonal and monoclinic) zirconia polymorphs using the atomic superposition method. Theoretical data are compared with the measured positron lifetime for cubic and tetragonal monocrystals of yttria‐stabilized zirconia (YSZ) and coincidence Doppler broadening measurements on tetragonal monocrystals of YSZ. Positron lifetime spectra of YSZ monocrystals exhibit a single component spectrum with lifetimes 178 ps and 174 ps for cubic and tetragonal phases, respectively. Possible interpretations of measured lifetime and Doppler data are discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phase transition studies in trans ‐stilbene crystal using 2D‐ACAR
Authors: Sivaji K. , Arul Chakkaravarthi A. , Selvakumar S. , Sankar S.
Published: August 2007

Two‐dimensional electron momentum distributions (EMD) mapping in a (c‐a) plane of molecular trans‐stilbene crystal have been made, using the two‐dimensional angular correlation of positron annihilation radiation (2D‐ACAR) at room temperature (RT), 210 K and 110 K. Further, we discuss the changes in static and dynamic electron momentum distribution and the positron behavior in molecular crystals at different temperatures to clarify their static and dynamic origin. An attempt has been made to visualize the electronic structure of organic molecular crystal trans‐stilbene during phase transition. The mapped EMD is explained with the combination of disordered to ordered transition concept and molecular vibration freezing model. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)