bluuebunny/crossref_metadata_2025 huggingface dataset:
Clinical improvement and shrinkage of uterine fibroids after thermal ablation by magnetic resonance‐guided focused ultrasound surgery
Authors: Rabinovici J. , Inbar Y. , Revel A. , Zalel Y. , Gomori J. M. , Itzchak Y. , Schiff E. , Yagel S.
Published: September 2007

Objective

Hysterectomy or myomectomy are the accepted treatments for symptomatic uterine fibroids. Heat ablation of uterine fibroids has been shown to be an effective alternative treatment. The aim of this study was to determine the clinical efficacy of non‐invasive thermal ablation by transcutaneous magnetic resonance‐guided high‐intensity focused ultrasound (MRgFUS) for the treatment of symptomatic uterine fibroids.

Methods

In this prospective study, MRgFUS ablation of uterine fibroids was performed in 35 symptomatic women scheduled for hysterectomy. Clinical symptoms, patient satisfaction and uterine size were determined at 1 month and 6 months after the procedure.

Results

This outpatient procedure was very well tolerated by all women. Sixty‐nine percent (24/35) of the treated patients reported either significant or partial improvement in symptoms. Treated fibroids decreased in volume by 12% and 15% at 1 and 6 months, respectively. Minor transient side‐effects were observed in two women. Six women underwent hysterectomy during the follow‐up period.

Conclusion

This study demonstrates the clinical efficacy of MRgFUS ablation of uterine fibroids. This novel, non‐invasive surgical approach may offer an alternative therapy for women with uterine fibroids. Copyright © 2007 ISUOG. Published by John Wiley & Sons, Ltd.
Progesterone vaginal gel for the reduction of recurrent preterm birth: primary results from a randomized, double‐blind, placebo‐controlled trial
Authors: O'Brien J. M. , Adair C. D. , Lewis D. F. , Hall D. R. , DEfranco E. A. , Fusey S. , Soma‐Pillay P. , Porter K. , How H. , Schackis R. , Eller D. , Trivedi Y. , Vanburen G. , Khandelwal M. , Trofatter K. , Vidyadhari D. , Vijayaraghavan J. , Weeks J. , Dattel B. , Newton E. , Chazotte C. , Valenzuela G. , Calda P. , Bsharat M. , Creasy G. W.
Published: September 2007

Objective

Preterm birth is the leading cause of perinatal morbidity and mortality worldwide. Treatment of preterm labor with tocolysis has not been successful in improving infant outcome. The administration of progesterone and related compounds has been proposed as a strategy to prevent preterm birth. The objective of this trial was to determine whether prophylactic administration of vaginal progesterone reduces the risk of preterm birth in women with a history of spontaneous preterm birth.

Methods

This randomized, double‐blind, placebo‐ controlled, multinational trial enrolled and randomized 659 pregnant women with a history of spontaneous preterm birth. Between 18 + 0 and 22 + 6 weeks of gestation, patients were assigned randomly to once‐daily treatment with either progesterone vaginal gel or placebo until either delivery, 37 weeks' gestation or development of preterm rupture of membranes. The primary outcome was preterm birth at ≤ 32 weeks of gestation. The trial was analyzed using an intent‐to‐treat strategy.

Results

Baseline characteristics were similar in the two treatment groups. Progesterone did not decrease the frequency of preterm birth at ≤ 32 weeks. There was no difference between the groups with respect to the mean gestational age at delivery, infant morbidity or mortality or other maternal or neonatal outcome measures. Adverse events during the course of treatment were similar for the two groups.

Conclusion

Prophylactic treatment with vaginal progesterone did not reduce the frequency of recurrent preterm birth (≤ 32 weeks) in women with a history of spontaneous preterm birth. The effect of progesterone administration in patients at high risk for preterm delivery as determined by methods other than history alone (e.g. sonographic cervical length) requires further investigation. Copyright © 2007 ISUOG. Published by John Wiley & Sons, Ltd.
Fatty acid compositions of corn oils in relation to oil contents of the kernels
Authors: Sniegowski M. S. , Baldwin A. R.
Published: October 2007

The fatty acid compositions of 13 oils from corns having oil contents over the range of 1.6 to 11.5% oil, d.b., were determined either by a spectrophotometric technique applied to the whole oil or by the methyl ester fractional distillation technique. Linear relationships between iodine values and fatty acid compositions, between oil contents of the corns and iodine values, and between oil contents and fatty acid compositions were determined. An increase in oil content of the corn is accompanied by a decrease in iodine value and linoleic acid content of the oil and by an increase in oleic acid and saturated acids.
The Significance of Employment for Chronic Stress and Psychological Distress among Rural Single Mothers
Authors: Turner Heather A.
Published: October 2007

Considerable research has found elevated levels of stress and psychological distress among single mothers. However, little research has addressed the relevance of employment for stress processes in this population, and few studies have focused on links between employment, stress, and mental health among single mothers living inruralareas. Based on a probability sample of 508 single mothers age 18–39 living in rural Northern New England, this study: (1) documents variations in chronic stress and psychological distress for employed and unemployed single mothers, (2) considers the extent to which different forms of chronic stress mediate or explain the employment‐distress relationship, and (3) examines whether employment status modifies associations between chronic stress and psychological distress. Findings indicated that rural single mothers who were employed reported significantly less financial stress, childcare stress, and rural residence stress, relative to mothers who were not employed, independent of variety of other factors. Employed mothers also experienced significantly less psychological distress which was partially mediating by their lower financial stress. However, there was also a statistical interaction between employment status and financial stress such that the harmful effect of financial stress on well‐being wasgreaterfor employed women. Implications of the findings are discussed.
Work Barriers in the Context of Pathways to the Employment of Welfare‐to‐Work Clients
Authors: Lee Shawna J. , Vinokur Amiram D.
Published: October 2007

The ability of welfare‐to‐work clients to leave the welfare rolls and stay in the labor force is often limited by the work barriers they face. Using a sample of 1,404 female welfare‐to‐work clients we first examined the structure of work barriers and then tested their contribution to current work status in the context of a structural equation model that incorporated other central pathways to employment. Whereas work barriers included diverse factors ranging from lack of transportation to low quality jobs, they were shown to constitute a uni‐dimensional construct. Furthermore, work barriers had a net adverse effect on employment outcomes, controlling for job search self‐efficacy and employment intention. We conclude with discussion of implications for the development of welfare‐to‐work programs and interventions that target low‐income women.
Dorsolateral prefrontal N-acetyl-aspartate concentration in male patients with chronic schizophrenia and with chronic bipolar disorder
Authors: Molina V. , Sánchez J. , Sanz J. , Reig S. , Benito C. , Leal I. , Sarramea F. , Rebolledo R. , Palomo T. , Desco M.
Published: October 2007

Objectives

A study of N-acetyl-aspartate (NAA) can provide data of interest about cortical alterations in psychotic illnesses. Although a decreased NAA level in the cerebral cortex is a replicated finding in chronic schizophrenia, the data are less consistent for bipolar disease. On the other hand, it is likely that NAA values in schizophrenia may differ in men and women.

Methods

We used proton magnetic resonance spectroscopy (1H MRS) to examine NAA levels in the prefrontal cortex in two groups of male patients, one with schizophrenia (n = 11) and the other with bipolar disorder (n = 13) of similar duration, and compared them to a sample of healthy control males (n = 10). Additionally, we compared the degree of structural deviations from normal volumes of gray matter (GM) and cerebrospinal fluid (CSF) in the dorsolateral prefrontal cortex.

Results

Compared to controls, schizophrenia and bipolar patients presented decreased NAA to creatine ratios, while only the schizophrenia group showed an increase in CSF in the dorsolateral prefrontal region. There were no differences in choline to creatine ratios among the groups.

Conclusions

These data suggest that the decrease in NAA in the prefrontal region may be similar in schizophrenia and bipolar disorder, at least in the chronic state. However, cortical CSF may be markedly increased in schizophrenia patients.
Oleic acid: An efficient inhibitor of glucosyltransferase
Authors: Won Se-Ra , Hong Mi-Jung , Kim Yong-Mu , Li Chun Ying , Kim Jang-Won , Rhee Hae-Ik
Published: October 2007

Among the extracts from 420 kinds of herbs, Prunus salicina, showing the highest glucosyltransferase inhibition activity, was purified and designated GTI‐0163. Structural determination of GTI‐0163 revealed it to be an oleic acid‐based unsaturated fatty acid. GTI‐0163 was an uncompetitive inhibitor of GTase. Among the unsaturated fatty acids, oleic acid showed a significantly higher GTase inhibitory activity than the saturated fatty acids or the ester form of oleic acid. These results strongly suggested that both the number of double bonds and the existence of free carboxyl groups of fatty acids play an important role in GTase inhibitory activity.
Glycaemic index of common foods tested in the UK and India
Authors: Henry C. J. K. , Lightowler H. J. , Newens K. , Sudha V. , Radhika G. , Sathya R. M. , Mohan V.
Published: October 2007

The aim of this study was to ascertain whether international glycaemic index (GI) values, predominantly developed using peoples living in Europe, North America or Australia, are applicable to Asian Indians resident in their own country. Thirty-four Caucasian subjects were recruited in Oxford, UK and thirteen Asian Indian subjects in Chennai, India. Two types of sweet biscuits and three breakfast cereals were tested for glycaemic response in each group. Subjects were served equivalent available carbohydrate amounts (50 g) of test foods and a reference food (glucose), on separate occasions. Capillary blood glucose was measured from finger-prick samples in fasted subjects ( − 5 and 0 min) and at 15, 30, 45, 60, 90 and 120 min after starting to eat. For each test food, the incremental area under the curve (IAUC) and GI values were determined. Although the glycaemic response to the reference food was higher in Asian Indian subjects compared with UK Caucasian subjects (IAUC 219 mmol/min per litre v. 157 mmol/min per litre, respectively; P < 0·01), there was no significant difference in GI values of the five test foods between the two groups. This is the first study known to the authors to examine the role of ethnicity on GI when the subjects are resident in their own countries. The findings from this study have important implications for the use of the GI concept worldwide and support the application of international values to different ethnic groups. The higher glycaemic response to all foods in Asian Indians may represent another mechanism for increased diabetes susceptibility among Asian Indians.
Orally administeredLactobacillus plantarumreduces pro-inflammatory interleukin secretion in sera fromListeria monocytogenesinfected mice
Authors: Puertollano Elena , Puertollano María A. , Cruz-Chamorro Lidia , Álvarez de Cienfuegos Gerardo , Ruiz-Bravo Alfonso , de Pablo Manuel A.
Published: September 2007

Lactic acid bacteria have traditionally been thought to have immunomodulating effects. To verify this property,Lactobacillus plantarumwas orally administered to mice (5 × 107colony forming units (c.f.u.)), prior to infection withListeria monocytogenesin order to evaluate the host resistance against an infectious micro-organism and to better define the influence ofL. plantarumon such responses. Balb/c mice were treated daily withL. plantarumor received PBS (sham-treated mice as controls) for 4 weeks. Subsequently, mice were intravenously infected with a clinical isolate ofL. monocytogenes. Our study revealed that the administration ofL. plantarumdid not significantly increase the survival (P = 0·13) of mice (fifteen in each group) afterL. monocytogenesinfection (106 c.f.u./ml), whereas a sub-lethal dose ofL. monocytogenes(105 c.f.u./ml) was eliminated from liver and spleen 5 d after the challenge in bothL. plantarum- and sham-treated mice (n5). Nevertheless, the levels of IL-1β and IL-6 from sera of orally administeredL. plantarumwere drastically reduced at 0, 4 (P < 0·01) and 6 d afterL. monocytogenesinfection, whereas TNF-α production was unaltered. In conclusion, administration ofL. plantarumreduced pro-inflammatory IL production after challenge withL. monocytogenes, although it did not significantly impact the survival of mice. We speculate thatL. plantarumcould exert anti-inflammatory effects, which may represent an important model to reduce inflammatory disorders. Therefore, further studies in human subjects should determine the role ofL. plantarumas an immunomodulatory micro-organism and its relationship in the host protection to pathogens.
Phenotypic and genetic variations and correlations in multitrait developmental instability: a multivariate Bayesian model applied to Speckled Wood butterfly (Pararge aegeria) wing measurements
Authors: VAN DONGEN STEFAN , TALLOEN WILLEM
Published: September 2007

Phenotypic and genetic variation and covariation in developmental instability (DI) have been the subject of many debates. In this paper we develop and apply a statistical model in a Bayesian context to analyse different traits simultaneously in a multivariate model of DI. We apply the model to measurements of yellow spots on the front wing of the Speckled Wood butterfly (Pararge aegeriaL.) in a full-sib breeding experiment. We estimated the posterior distribution of the broad-sense heritability of DI averaged across the five yellow spots, which had a median of 0·19 and a 95% credibility interval ranging between 0·04 and 0·64. Phenotypic and genetic correlations in DI could not be estimated accurately with the present sample size. Yellow spots 4 and 5 appeared to show some degree of developmental integration. The importance of this model and its possible extensions are discussed.
Putative markers of infective life stages in Leishmania (Viannia) braziliensis
Authors: GAMBOA D. , VAN EYS G. , VICTOIR K. , TORRES K. , ADAUI V. , AREVALO J. , DUJARDIN J.-C.
Published: September 2007

Gene expression is known to vary significantly during the Leishmania life-cycle. Its monitoring might allow identification of molecular changes associated with the infective stages (metacyclics and amastigotes) and contribute to the understanding of the complex host-parasite relationships. So far, very few studies have been done on Leishmania (Viannia) braziliensis, one of the most pathogenic species. Such studies require, first of all, reference molecular markers. In the present work, we applied differential display analysis (DD analysis) in order to identify transcripts that might be (i) candidate markers of metacyclics and intracellular amastigotes of L. (V.) braziliensis or (ii) potential controls, i.e. constitutively expressed. In total, 48 DNA fragments gave reliable sequencing data, 29 of them being potential markers of infective stages and 12 potential controls. Eight sequences could be identified with reported genes. Validation of the results of DD analysis was done for 4 genes (2 differentially expressed and 2 controls) by quantitative real-time PCR. The infective insect stage-specific protein (meta 1) was more expressed in metacyclic-enriched preparations. The oligopeptidase b showed a higher expression in amastigotes. Two genes, glucose-6-phosphate dehydrogenase and a serine/threonine protein kinase, were found to be similarly expressed in the different biological samples.
Olfactory identification dysfunction, aggression and impulsivity in war veterans with post-traumatic stress disorder
Authors: Dileo J. F. , Brewer W. J. , Hopwood M. , Anderson V. , Creamer M.
Published: October 2007

Background

Due to neuropsychological conceptualizations of orbitoprefrontal cortex (OFC) dysfunction underpinning impulsive aggression and the incidence of such behaviour in post-traumatic stress disorder (PTSD), this study aimed to explore olfactory identification (OI) ability in war veterans with PTSD as a probe of putative OFC dysfunction; and to explore the utility of OI ability in predicting aggressive and impulsive behavior in this clinical population.

Method

Participants comprised 31 out-patient male war veterans with PTSD (mean=58.23 years, s.d.=2.56) recruited from a Melbourne Veterans Psychiatry Unit, and 31 healthy age- and gender-matched controls (mean=56.84 years, s.d.=7.24). All participants were assessed on clinical measures of PTSD, depression, anxiety, and alcohol misuse; olfactory identification; neurocognitive measures of dorsolateral prefrontal, lateral prefrontal and mesial temporal functioning; and self-report measures of aggression and impulsivity.

Results

War veterans with PTSD exhibited significant OI deficits (OIDs) compared to controls, despite uncompromised performance on cognitive measures. OIDs remained after covaring for IQ, anxiety, depression and alcohol misuse, and were significant predictors of aggression and impulsivity.

Conclusions

This research contributes to emerging evidence of orbitoprefrontal dysfunction in the pathophysiology underlying PTSD. This is the first study to report OIDs as a predictor of aggression and impulsivity in this clinical population. It prompts further exploration of the potential diagnostic utility of OIDs in the assessment of PTSD. Such measures may help delineate the clinical complexity of PTSD, and support more targeted interventions for individuals with a greater susceptibility to aggressive and impulsive behaviors.
Mechanism underlying rebound excitation in retinal ganglion cells
Authors: MITRA PRATIP , MILLER ROBERT F.
Published: October 2007

Retinal ganglion cells (RGCs) display the phenomenon of rebound excitation, which is observed as rebound sodium action potential firing initiated at the termination of a sustained hyperpolarization below the resting membrane potential (RMP). Rebound impulse firing, in contrast to corresponding firing elicited from rest, displayed a lower net voltage threshold, shorter latency and was invariably observed as a phasic burst-like doublet of spikes. The preceding hyperpolarization leads to the recruitment of a Tetrodotoxin-insensitive depolarizing voltage overshoot, termed as the net depolarizing overshoot (NDO). Based on pharmacological sensitivities, we provide evidence that the NDO is composed of two independent but interacting components, including (1) a regenerative low threshold calcium spike (LTCS) and (2) a non-regenerative overshoot (NRO). Using voltage and current clamp recordings, we demonstrate that amphibian RGCs possess the hyperpolarization activated mixed cation channels/current,Ih, and low voltage activated (LVA) calcium channels, which underlie the generation of the NRO and LTCS respectively. At the RMP, theIhchannels are closed and the LVA calcium channels are inactivated. A hyperpolarization of sufficient magnitude and duration activatesIhand removes the inactivation of the LVA calcium channels. On termination of the hyperpolarizing influence,Ihadds an immediate depolarizing influence that boosts the generation of the LTCS. The concerted action of both conductances results in a larger amplitude and shorter latency NDO than either mechanism could achieve on its own. The NDO boosts the generation of conventional sodium spikes which are triggered on its upstroke and crest, thus eliciting rebound excitation.
Short Note: The Antarctic toothfish: how common a prey for Weddell seals?
Authors: Ponganis P.J. , Stockard T.K.
Published: October 2007

The Antarctic toothfish (Dissostichus mawsoniNorman) has been considered an occasional large prey item of the Weddell seal (Leptonychotes weddelliiLesson) (Kooyman 1967, Calhaem & Christoffel 1969, Testaet al. 1985, Castelliniet al. 1992, Daviset al. 1999, Fuimanet al. 2002). The seal's most common prey is the Antarctic silverfish (Pleuragramma antarcticumBoulenger) as well as benthic and sub-ice fish, cephalopods, and crustaceans (Dearborn 1965, Green & Burton 1987, Plotz 1987, Plotzet al. 1991, Castelliniet al. 1992, Burnset al. 1998).
Optimal harvesting during an invasion of a sublethal plant pathogen
Authors: GAFF HOLLY , JOSHI HEM RAJ , LENHART SUZANNE
Published: October 2007

Plant pathogens are quite destructive to cash crops throughout the world, resulting in potentially devastating financial losses. This work expands recently developed optimal control theory for an integrodifference model to a mathematical system which includes an integrodifference component. This system models a highly simplified plant pathogen system for which the optimal harvesting scheme is derived. An adjoint system is introduced to characterize the optimal harvesting pattern. This analysis shows that, while it may not be possible to prevent losses upon discovery of the pathogen in an area, it is theoretically possible to significantly cut those losses by culling an area around the initial infection.
Economic incentives and mathematical models of disease
Authors: KLEIN EILI , LAXMINARAYAN RAMANAN , SMITH DAVID L. , GILLIGAN CHRISTOPHER A.
Published: October 2007

The fields of epidemiological disease modeling and economics have tended to work independently of each other despite their common reliance on the language of mathematics and exploration of similar questions related to human behavior and infectious disease. This paper explores the benefits of incorporating simple economic principles of individual behavior and resource optimization into epidemiological models, reviews related research, and indicates how future cross-discipline collaborations can generate more accurate models of disease and its control to guide policy makers.
Nutritional status of the Andean population of Puna and Quebrada of Humahuaca, Jujuy, Argentina
Authors: Romaguera D , Samman N , Farfán N , Lobo M , Pons A , Tur JA
Published: September 2007

Objective

To assess the nutritional status of the Andean population of Puna and Quebrada of Humahuaca, Jujuy, using anthropometric measurements.

Design and subjects

A cross-sectional nutritional survey was carried out in a representative sample (n = 1236) of individuals from these regions. Children aged 2–9 years, adolescents (10–17 years) and adults (≥18 years; pregnant and lactating women excluded) were considered. Height-for-age, weight-for-height and body mass index (BMI) were calculated in children and adolescents and compared with World Health Organization/National Center for Health Statistics/Centers for Disease Control and Prevention reference standards using Z-scores or percentiles, in order to assess the prevalence of stunting, wasting/thinness and excess weight. In adults, BMI, waist circumference (WC) and waist-to-hip (WHR) ratio were used to identify obesity and central adiposity.

Results

Stunting (height-for-age Z-score <–2 standard deviations) and obesity (BMI ≥ 95th percentile) were found to be major nutritional problems in children and adolescents. Stunting was prevalent in 10.7% of children and 12.4% of adolescents; 8.2% of children and 3.5% of adolescents were obese. Adults were short (mean: 155.8 cm) and values of overweight (32.3%), obesity (18.3%) and central adiposity (mean WC: 86.5 cm) were high. Older adults and those with higher economic development showed higher prevalence of obesity and central adiposity.

Conclusions

The present population may be at the early stages of nutritional transition as symptoms of undernutrition and overnutrition coexist at the population level. These results suggest that rates of growth retardation may be decreasing owing to improved nutritional conditions; however, this could be accompanied by a sharp increase in the prevalence of other diet-related chronic diseases.
Iron and zinc deficiencies in China: what is a feasible and cost-effective strategy?
Authors: Ma Guansheng , Jin Ying , Li Yanping , Zhai Fengying , Kok Frans J , Jacobsen Evert , Yang Xiaoguang
Published: September 2007

In order to prioritise interventions for micronutrient deficiencies in China, the populations affected by iron and zinc deficiencies were assessed based on data from the 2002 China National Nutrition and Health Survey. The costs and cost-effectiveness of supplementation, food diversification and food fortification were estimated using the standard World Health Organization ingredients approach. Results indicated that 30% of children (<2 years), adults (>60 years), pregnant and lactating women, and 20% of women of reproductive age were anaemic, some 245 million people. Approximately 100 million people were affected by zinc deficiency (zinc intake inadequacy and stunting), the majority living in rural areas. Among interventions on iron and zinc deficiency, biofortification showed the lowest costs per capita, I$0.01 (international dollars), while dietary diversification through health education represented the highest costs at I$1148. The cost-effectiveness of supplementation, food fortification and dietary diversification for iron deficiency alone was I$179, I$66 and I$103 per disability-adjusted life-year (DALY), respectively. Data for biofortification were not available. For zinc deficiency, the corresponding figures were I$399, I$153 and I$103 per DALY, respectively. In conclusion, iron and zinc deficiencies are of great public health concern in China. Of the two long-term intervention strategies, i.e. dietary diversification and biofortification with improved varieties, the latter is especially feasible and cost-effective for rural populations. Supplementation and fortification can be used as short-term strategies for specific groups.
A Multivariate, Multilevel Analysis of the Relationship Between Cognitive Abilities and Scholastic Achievement
Authors: Freund Philipp Alexander , Holling Heinz , Preckel Franzis
Published: October 2007

Abstract. This study investigates the relationship between scholastic achievement (teacher-assigned grades) and cognitive abilities while explicitly modeling the multilevel structure of a large data set from an educational context. A multivariate analysis of composite scores in three subject domains (math and natural sciences, languages, and social sciences) was conducted using as predictors reasoning capacity, creativity, memory, and speed as well as student gender and type of school attended. The results showed meaningful differences in the relationships between the different abilities and school grades, and also significant contributions from student gender and school type. Specifically, reasoning capacity had the largest impact on achievement in math and natural sciences, whereas creativity explained more variability in performance for social sciences. Furthermore, girls outperformed boys. There was significant random variation in the intercepts at the between-classroom level, indicating that students sharing a common educational and ecological background tend to have more similar teacher-assigned grades when compared to students in other classrooms. Yet, there was no significant slope variation between the classrooms, which points to stable relationships between cognitive abilities and scholastic achievement.
The Structure Among Measures of Personality, Social Attitudes, Values, and Social Norms
Authors: Stankov Lazar
Published: October 2007

Abstract. This paper presents the results of a study that employed measures of personality, social attitudes, values, and social norms that have been the focus of recent research in individual differences. These measures were given to a sample of participants (N = 1,255) who were enrolled at 25 US colleges and universities. Factor analysis of the correlation matrix produced four factors. Three of these factors corresponded to the domains of Personality/Amoral Social Attitudes, Values, and Social Norms; one factor, Conservatism, cut across the domains. Cognitive ability showed negative correlation with conservatism and amoral social attitudes. The study also examined gender and ethnic group differences on factor scores. The overall interpretation of the findings is consistent with the inside-out view of human social interactions.
Comparison of a SAFIR lightning detection network in northern Germany to the operational BLIDS network
Authors: Drüe C. , Hauf T. , Finke U. , Keyn S. , Kreyer O.
Published: September 2007

This paper presents a comparison of a regional lightning detection network based on SAFIR sensors (Surveillance et Alerte Foudre par Interférometrie Radioélectrique) with the operational German lightning detection system (BLIDS) that uses LPATS (Lightning Positioning and Tracking System) and IMPACT (Improved Performance from Combined Technology) sensors. The Institute for Meteorology and Climatology (IMUK) of the University of Hannover runs a regional lightning detection network in northern Germany (UHSN). It consists of three SAFIR receiving stations in a triangle of about 180 km side‐length. As an a priori assumption that either BLIDS or UHSN represents the truth is not possible, the relative performance of each system in comparison with the other one is investigated. Probability of detection (POD) is used to investigate flash events simultaneously sensed by both networks. POD of UHSN was calculated assuming BLIDS measurements as true and, vice versa, POD of BLIDS was calculated assuming UHSN measurements as true. This comparison yielded that UHSN, as expected, is far more sensitive to intracloud lightning. In contrast, the sensitivity of UHSN for cloud‐to‐ground lightning was much lower than that of the BLIDS network. Hence the sensitivity of UHSN for both lightning types together (total lightning) is dominated by intracloud lightning and is consequently higher than that for BLIDS. The sensitivity of UHSN was found to exhibit strong horizontal variations. These are dominated by the network geometry and data processing procedures. The present study shows strengths and weaknesses of both systems and contributes to a better assessment of the potentials of each system.
Multicomponent reactive transport simulation of the Elder problem: Effects of chemical reactions on salt plume development
Authors: Post V. E. A. , Prommer H.
Published: October 2007

A numerical modeling approach was used to investigate the relevancy of the feedback mechanisms between geochemical reactions and variable density flow during free convection. The problem was studied by reformulating the classic Elder problem as a reactive multicomponent transport problem. It was found that for the studied system, the importance of this feedback decreased with increasing density contrast between intruding salinized water and the ambient fresh water body. For the smaller density contrasts, the flow patterns that develop during intrusion in the reactive simulations are characterized by different convection cells, higher rates of plume descent, and an increase in the total mass of solutes by up to 22% at the end of the simulation compared to the nonreactive simulations. For field situations, the results suggest that it may be necessary to consider the feedback between reactions and variable density flow where subtle density variations drive flow such as in contaminant plumes. For seawater intrusion problems, however, the feedback mechanism appears to be negligible for most cases.
The laminar flow field at the interface of a Sierpinski carpet configuration
Authors: Rosenzweig Ravid , Shavit Uri
Published: October 2007

The problem of laminar flow in a combined free and saturated porous domain was investigated using a Sierpinski carpet configuration. The three‐dimensional steady state microscale velocities were measured using a particle image velocimeter and computed numerically. The macroscale velocity profiles were then obtained by averaging the microscale velocities. A comparison between the measured and computed velocities showed a good fit. The macroscale velocity profile was calculated using the modified Brinkman equation (MBE), which was recently derived for two‐dimensional brush configurations. The MBE was developed for unidirectional, laminar flows, assuming that the porous medium planar porosity follows a step function. A new analytical solution of the MBE was developed and applied using no calibration or curve fitting. It was shown that although the MBE was originally derived for a unidirectional microscopic flow field, the macroscopic representation of the complex microscopic flow in the Sierpinski configuration can be well described by the solutions of the MBE.
CO2 inhibition of global terrestrial isoprene emissions: Potential implications for atmospheric chemistry
Authors: Arneth Almut , Miller Paul A. , Scholze Marko , Hickler Thomas , Schurgers Guy , Smith Benjamin , Prentice I. Colin
Published: September 2007

Isoprene is the dominant volatile organic compound produced by the terrestrial biosphere and fundamental for atmospheric composition and climate. It constrains the concentration of tropospheric oxidants, affecting the lifetime of other reduced species such as methane and contributing to ozone production. Oxidation products of isoprene contribute to aerosol growth. Recent consensus holds that emissions were low during glacial periods (helping to explain low methane concentrations), while high emissions (contributing to high ozone concentrations) can be expected in a greenhouse world, due to positive relationships with temperature and terrestrial productivity. However, this response is offset when the recently demonstrated inhibition of leaf isoprene emissions by increasing atmospheric CO2 concentration is accounted for in a process‐based model. Thus, isoprene may play a small role in determining pre‐industrial tropospheric OH concentration and glacial‐interglacial methane trends, while predictions of high future tropospheric O3 concentrations partly driven by isoprene emissions may need to be revised.
Longitude sector comparisons of storm enhanced density
Authors: Coster A. J. , Colerico M. J. , Foster J. C. , Rideout W. , Rich F.
Published: September 2007

Examples of storm enhanced density (SED) formation over Russia and Northern Europe are presented. These events, which persisted 15–20 hours, were fixed in local time near noon over Europe and then later observed over the American sector. The amount of total electron content (TEC) at the base of the SED erosion plume is found to be greatest in the American sector. A persistent, repeatable pattern is apparent in the time evolution of the latitude location of the SED plume base, although the latitudinal rate of change differs between the two sectors. In the European sector the invariant latitude (Λ) of the SED plume base is observed to be between 61°–63° Λ and at a time close to local noon. In the American sector, the position of the base of the plume shifts from local noon towards dusk, and moves to a lower latitude at a nearly fixed longitude.
Observed and modeled HOCl profiles in the midlatitude stratosphere: Implication for ozone loss
Authors: Kovalenko L. J. , Jucks K. W. , Salawitch R. J. , Toon G. C. , Blavier J.‐F. , Johnson D. G. , Kleinböhl A. , Livesey N. J. , Margitan J. J. , Pickett H. M. , Santee M. L. , Sen B. , Stachnik R. A. , Waters J. W.
Published: October 2007

Vertical profiles of stratospheric HOCl calculated with a diurnal steady‐state photochemical model that uses currently recommended reaction rates and photolysis cross sections underestimate observed profiles of HOCl obtained by two balloon‐borne instruments, FIRS‐2 (a far‐infrared emission spectrometer) and MkIV (a mid‐infrared, solar absorption spectrometer). Considerable uncertainty (a factor of two) persists in laboratory measurements of the rate constant (k1) for the reaction ClO + HO2 → HOCl + O2. Agreement between modeled and measured HOCl can be attained using a value of k1 from Stimpfle et al. (1979) that is about a factor‐of‐two faster than the currently recommended rate constant. Comparison of modeled and measured HOCl suggests that models using the currently recommended value for k1 may underestimate the role of the HOCl catalytic cycle for ozone depletion, important in the midlatitude lower stratosphere.
Near‐terminator Venus ionosphere: Evidence for a dawn/dusk asymmetry in the thermosphere
Authors: Fox J. L. , Kasprzak W. T.
Published: September 2007

Recent models of the near‐terminator ionosphere of Venus constructed using neutral density profiles from the VTS3 model of Hedin et al. (1983) have shown that altitudes of the electron density peaks are in agreement with those measured by Pioneer Venus (PV) Orbiter Radio Occultation (ORO) and other radio occultation profiles in the solar zenith angle (SZA) range 60 to 70°, where they are near 140 km (Fox, 2007). The model peaks in the 75–85° range, however, do not decrease in altitude to near 135 km, as do the PV ORO electron density peaks shown in the study of Cravens et al. (1981). We investigate here possible reasons for this decrease. The PV Orbiter Neutral Mass Spectrometer (ONMS) measured densities of CO2, O, CO, N2, N, and He for many of the first 600 orbits. We have chosen 10 orbits in the dawn sector and 12 orbits in the dusk sector for which the solar zenith angles at periapsis were in the 75–85° range, and we have examined the ONMS density profiles reported in the PV Unified Abstract Data System. We find that for most of the orbits, the appropriately normalized ONMS measured densities for CO2 and O are, however, either similar to or larger than those generated from the VTS3 model for the same solar zenith angle and F10.7 flux, and the use of these densities in our models would therefore produce a higher, rather than a lower, peak. The VTS3 models are, however, not expected to be accurate in the terminator region because of the small number of spherical harmonics used in the models and the large density changes that are expected near the terminators. We have also investigated a possible dawn/dusk asymmetry in the ionosphere. All the low‐altitude PV radio occultation electron density peaks reported in the study of Cravens et al. (1981) in the 70 to 85° range were in the dawn sector at high latitudes. In the VTS3 models, the exospheric temperatures are predicted to be smaller at dawn that at dusk, but the asymmetries are confined to the region above ∼165 km. Thus use of the VTS3 model densities and temperatures in the near‐terminator dawn sector models cannot produce electron density peaks that are lower in altitude than those in the dusk sector. We suggest that there is a high‐latitude asymmetry between the dawn and dusk neutral densities that extends down to within ∼20 km above the expected altitude of the electron density peaks, and that produces a significantly asymmetrical ionosphere.
Relationship of waist and hip circumference with coagulation and fibrinolysis in postmenopausal women
Authors: Peverill Roger E. , Teede Helena J. , Malan Erica , Kotsopoulos Dimitra , Smolich Joseph J. , Mcgrath Barry P.
Published: October 2007

The contribution of obesity to the occurrence of cardiovascular events may not be wholly related to its influence on traditional risk factors. Coagulation and fibrinolysis may also influence cardiovascular risk, but the relationship of adiposity with these processes is unclear. The aim of the present study was to investigate the relationships of BMI (body mass index), waist circumference, hip circumference and WHR (waist-to-hip ratio) with VIIc (factor VII activity), plasma markers of thrombin generation [F1+2 (prothrombin fragment 1+2)], fibrin formation [SF (soluble fibrin)] and fibrin turnover (D-dimer), and PAI-1 (plasminogen activator inhibitor-1; a marker of fibrinolytic inhibitory capacity). The study cohort was 80 healthy postmenopausal women who were not diabetic, current smokers or taking hormone therapy and who had a fasting sample of blood collected. VIIc, F1+2, SF and PAI-1 were all positively correlated with BMI, waist circumference and WHR, whereas D-dimer was positively correlated with waist circumference and WHR, but not BMI. WHR was the strongest correlate of all the markers except for PAI-1, which was most closely related to BMI. Hip circumference became a negative correlate of F1+2 and D-dimer after adjusting for waist circumference. The relationships of WHR with F1+2 and SF, but not with VIIc and D-dimer, were independent of traditional risk factors. The positive association between waist circumference and markers of thrombin generation, fibrin production and fibrin turnover suggests that abdominal adiposity may contribute to atherothrombosis by activating intravascular coagulation. In contrast, a larger hip circumference appears to have a protective affect against coagulation activation.
Interventional Nephrology and Dialysis: The Role of Sonography in the Planning of Arteriovenous Fistulas for Hemodialysis
Authors: Malovrh Marko
Published: October 2007

Patients presenting for initial access evaluation in contemporary practice are less likely to have arteries and veins suitable for native fistula (AVF) formation in the classic location. Physical examination of the upper extremity alone may be inadequate for selection of arteries and veins that will mature into a functioning AF. The purpose of this paper is to determine how duplex ultrasonography can be used as an effective modality for the preoperative evaluation of vessels before construction of arteriovenous fistula for hemodialysis. The author have used duplex ultrasound (DU) to assess upper‐extremity vasculature for planning of dialysis access procedures. Criteria for selection of arteries and veins and a detailed description of DU examination protocol are reviewed. Routine use of upper‐extremity DU has identified many patients with veins that are suitable for use and determined arteries with optimal arterial inflow for successful AFV creation.
Incipient ferroelectricity and microwave dielectric resonance properties of CaCu2.85Mn0.15Ti4O12 ceramics
Authors: Li Ming , Feteira Antonio , Sinclair Derek C. , West Anthony R.
Published: September 2007

Mn-doped CaCu3Ti4O12 ceramics with nominal composition CaCu2.85Mn0.15Ti4O12 (CCMTO) have been prepared and their radio- and micro-wave dielectric properties established. At 300 K, dense CCMTO ceramics have appreciable grain resistivity, ∼20MΩcm, and exhibit microwave dielectric resonance with εr∼93, Qf∼3950GHz (at 3.95GHz) and temperature coefficient of resonant frequency ∼+657ppm∕K. εr decreases smoothly from ∼150 to 90 in the range of 10–300K, obeys the Curie-Weiss law in the range of ∼60–180K, and is consistent with incipient ferroelectricity. The source of the incipient ferroelectricity and potential applications of CCMTO ceramics are discussed.
A Fock space coupled cluster study on the electronic structure of the UO2, UO2+, U4+, and U5+ species
Authors: Infante Ivan , Eliav Ephraim , Vilkas Marius J. , Ishikawa Yasuyuki , Kaldor Uzi , Visscher Lucas
Published: September 2007

The ground and excited states of the UO2 molecule have been studied using a Dirac-Coulomb intermediate Hamiltonian Fock-space coupled cluster approach (DC-IHFSCC). This method is unique in describing dynamic and nondynamic correlation energies at relatively low computational cost. Spin-orbit coupling effects have been fully included by utilizing the four-component Dirac-Coulomb Hamiltonian from the outset. Complementary calculations on the ionized systems UO2+ and UO22+ as well as on the ions U4+ and U5+ were performed to assess the accuracy of this method. The latter calculations improve upon previously published theoretical work. Our calculations confirm the assignment of the ground state of the UO2 molecule as a Φ2u3 state that arises from the 5f17s1 configuration. The first state from the 5f2 configuration is found above 10000cm−1, whereas the first state from the 5f16d1 configuration is found at 5047cm−1.
Nanoparticles in nematic liquid crystals: Interactions with nanochannels
Authors: Hung Francisco R. , Gettelfinger Brian T. , Koenig Gary M. , Abbott Nicholas L. , de Pablo Juan J.
Published: September 2007

A mesoscale theory for the tensor order parameter Q is used to investigate the structures that arise when spherical nanoparticles are suspended in confined nematic liquid crystals (NLCs). The NLC is “sandwiched” between a wall and a small channel. The potential of mean force is determined between particles and the bottom of the channels or between several particles. Our results suggest that strong NLC-mediated interactions between the particles and the sidewalls of the channels, on the order of hundreds of kBT, arise when the colloids are inside the channels. The magnitude of the channel-particle interactions is dictated by a combination of two factors, namely, the type of defect structures that develop when a nanoparticle is inside a channel, and the degree of ordering of the nematic in the region between the colloid and the nanochannel. The channel-particle interactions become stronger as the nanoparticle diameter becomes commensurate with the nanochannel width. Nanochannel geometry also affects the channel-particle interactions. Among the different geometries considered, a cylindrical channel seems to provide the strongest interactions. Our calculations suggest that small variations in geometry, such as removing the sharp edges of the channels, can lead to important reductions in channel-particle interactions. Our calculations for systems of several nanoparticles indicate that linear arrays of colloids with Saturn ring defects, which for some physical conditions are not stable in a bulk system, can be stabilized inside the nanochannels. These results suggest that nanochannels and NLCs could be used to direct the assembly of nanoparticles into ordered arrays with unusual morphologies.