bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of the Highland Border Ophiolite in the ∼ 470 Ma Grampian Event, Scotland
Authors: TANNER P. W. G.
Published: April 2007

Field and petrological studies of the Highland Border Ophiolite demonstrate that it was obducted onto the Neoproterozoic–Ordovician rocks of the Dalradian block, and not emplaced against them by post-orogenic strike-slip movement. It was welded onto the upper, southward-younging limb of the already recumbent Tay Nappe (D1), and deformed by the Downbend Antiform (D4). However, its emplacement was not accompanied by significant internal deformation of the Dalradian block. As the ophiolite is correlated with those at Clew Bay, Tyrone and Shetland, this result will necessitate complete revision of the current model for basin closure on the southeastern margin of Laurentia.
Sedimentary history of a Mississippian to Pennsylvanian coal-bearing succession: an example from the Upper Silesia Coal Basin, Poland
Authors: KĘDZIOR ARTUR , GRADZIŃSKI RYSZARD , DOKTOR MAREK , GMUR DARIUSZ
Published: April 2007

The coal-bearing succession of the Upper Silesia Coal Basin consists of deposits filling a flexural foredeep basin. Accumulation initially compensated for regional and differentiated subsidence, after which the general depositional surface remained nearly flat. The deposition of the coal-bearing succession started at the end of Mississippian times (Pendleian Subage) and continued with hiatuses through almost the whole of Pennsylvanian times, and stopped in the Westphalian D Subage. The up to 8500 m thick coal-bearing succession traditionally has been divided into four main units called ‘Series’, and all of them are subdivided into subsidiary units known as ‘Beds’. The occurrence of the intervals containing marine faunas within the lower ‘Paralic’ part of the coal-bearing succession resulted from eustatic ingressions. The higher ‘Limnic’ part of the succession was laid down in fluvial systems, while the lower part was formed mostly in a fluvial and, to a lesser extent, complex coastal system. Sedimentation of the coal-bearing succession was controlled by both autogenic and allogenic factors.
DETERMINANTS OF CURRENT CONTRACEPTIVE USE AND METHOD CHOICE IN MONGOLIA
Authors: GERELTUYA ALTANKHUYAGIIN , FALKINGHAM JANE , BROWN JAMES
Published: April 2007

This study examines the determinants of current contraceptive use and method choice in Mongolia using data from the 1998 Mongolian Reproductive Health Survey and 2000 Mongolian Population and Housing Census. Since 1976, access to modern contraceptives has been liberalized and all restrictions on the use, distribution and import of contraceptives were removed in 1989. There were some increases in the use of modern contraceptives among married women in the 1990s; however, at the start of the twenty-first century the IUD and periodic abstinence remain the most widely used methods. Women with higher levels of education are more likely to be current users of contraception, and if they are current users, they are more likely to choose the IUD and traditional methods. Women living in rural areas have a higher probability of using contraception and are more likely to choose the IUD and traditional methods. Significant variations exist between primary sampling units in current contraceptive use and in the choice of modern methods. Community-level variables were important predictors in reducing variation between primary sampling unit, when other modern methods were compared with traditional methods.
Is bacterial colonisation of the tonsillar fossa a factor in post-tonsillectomy haemorrhage?
Authors: Stephens J C , Georgalas C , Kyi M , Ghufoor K
Published: April 2007

Objectives:

To identify if there is a link between bacterial colonisation of the tonsillar fossa and post-tonsillectomy haemorrhage.

Study design and setting:

Prospective non-interventional study of 105 patients who underwent tonsillectomy during a seven-month period. The study took place in a secondary care centre, the West Middlesex University Hospital.

Participants:

The participants were 105 patients who consecutively underwent tonsillectomy. The exclusion criteria were any patients with suspected or known malignancy, or known bleeding dyscrasias. The participants underwent microbiological sampling of the tonsil pre-operatively.

Main outcomes measures:

The outcome measures were primary or secondary bleeding, defined as any evidence of haemorrhage in the tonsillar fossae.

Results:

Twenty-four per cent of patients undergoing tonsillectomy had positive cultures from their tonsils pre-operatively. Patients with bacterial colonisation of the tonsillar fossa pre-operatively had an increased rate of post-tonsillectomy haemorrhage (odds ratio: 3.8, 1.1–12.1, 95 per cent confidence intervals,p = 0.04).

Conclusion:

This prospective study has found a relationship between bacterial colonisation of the tonsillar fossa and post-tonsillectomy haemorrhage. This suggests that there may be an argument for the use of antibiotics in those cases with positive pre-operative cultures. In view of the types of pathogens isolated, we feel that the management of a post-tonsillectomy bleed should include a beta lactamase inhibiting antibiotic.
Effectiveness of corticosteroids in otitis media with effusion: an experimental study
Authors: Yaman H , Ozturk K , Uyar Y , Gurbilek M
Published: April 2007

Objective:

The aim of the present study was to investigate the dose-related effectiveness of corticosteroids in the management of otitis media with effusion, by using the objective assessment techniques of tympanometry and cytokine measurement.

Materials and methods:

The eustachian tubes of 42 male rats were obstructed. Thirty-six subjects with effusion were randomly divided into three equal groups: controls; 0.5 mg/kg/day corticosteroid; and 1 mg/kg/day corticosteroid. Concentrations of interleukin-1β and tumour necrosis factor α in the middle-ear effusions were analysed using enzyme-linked immunosorbent assay.

Results:

An effusion occurred on the 14th post-operative day and was present on the 30th post-operative day in the control group. Otomicroscopic examination and tympanometric measurement showed an improvement in the intervention groups. There was a significant difference between both intervention groups and the control group for both interleukin-1β and tumour necrosis factor α concentrations (p < 0.01). However, there was no significant difference between the 0.5 mg/kg and the 1 mg/kg corticosteroid groups (p > 0.05).

Conclusion:

The study confirmed a short term beneficial effect of systemic steroids on resolution of otitis media with effusion in a rat model. Our results support the theory that corticosteroids significantly decrease concentrations of both interleukin-1β and tumour necrosis factor α. In our model, the 0.5 mg/kg corticosteroid dose was as effective as the 1 mg/kg corticosteroid dose. Further studies should be carried out to determine the optimal dose and duration of corticosteroids in the treatment of otitis media with effusion.
Recurrent facial paraesthesia secondary to maxillary antral cyst and dehiscent infraorbital canal: case report
Authors: Sharma N , De M , Pracy P
Published: April 2007

Objectives: To report a rare presentation of dehiscent infraorbital canal associated with a maxillary antral cyst.

Case report: A 26-year-old woman presented with symptoms of right infraorbital nerve dysfunction experienced while travelling by aeroplane. She was subsequently diagnosed with dehiscent infraorbital canal and large maxillary antral cyst on computed tomography scanning. The cyst was removed by endoscopic sinus surgery, and the patient's symptoms resolved.

Discussion: The effects of barotrauma on the ears and paranasal sinuses are reviewed. This is the first report of infraorbital nerve dysfunction caused by altered atmospheric pressure in the presence of dehiscent infraorbital canal and maxillary antral cyst. Endoscopic sinus surgery was successful in relieving the symptoms in this case.
Identification and characterization of a putative agglutination/immobilization antigen on the surface ofCryptocaryon irritans
Authors: HATANAKA A. , UMEDA N. , YAMASHITA S. , HIRAZAWA N.
Published: April 2007

The ciliated protozoanCryptocaryon irritans, a parasite of seawater fishes, was found to express an antigen that elicits antibodies in rabbits and tiger puffer (Takifugu ruburipes). Serum from rabbits and fish immunized with theronts had agglutination/immobilization activity against therontsin vitro; fish serum antibody levels (measured by enzyme-linked immunosorbent assays: ELISA) correlated with this activity. Anti-theront antibody levels in fish were significantly higher in the immunized group as compared with control fish at 2 weeks after booster immunization (injection of bovine serum albumin; Student'st-test,P<0·01). Biochemical analyses indicated that a Triton X-114-soluble 32 kDa theront integral membrane protein may be the agglutination/immobilization antigen. Indirect immunofluorescence staining of theronts suggested that this 32 kDa antigen was expressed on the surface of cilia. The full-length 32 kDa antigen cDNA contained 1147 basepairs, encoding a 328-amino acid protein including hydrophobic N- and C-termini. As withTetrahymenaandParameciumspp., TAA and TAG appear to be used as glutamine codons in the 32 kDa antigen gene.
Development and validation of flow cytometric measurement for parasitaemia using autofluorescence and YOYO-1 in rodent malaria
Authors: XIE L. , LI Q. , JOHNSON J. , ZHANG J. , MILHOUS W. , KYLE D.
Published: April 2007

An automated flow cytometric (FCM) detection method has been developed and validated with a simple diagnostic procedure in parasitized erythrocytes of Plasmodium berghei-infected rats using the nucleic acid-binding fluorescent dye YOYO-1. High levels of reticulocytes were detected during the course of the infection, ranging from 1·2–51·2%, but any RNA potentially confounding the assay could be removed by digestion with RNAse. The cell counts of uninfected, infected, and nucleated cells occurred with high precision. The cells were divided into different populations according to their physical or chemical properties but various factors within the assay such as cell fixation, RNA digestion, and compensation required optimization. In this study, FCM greatly simplified and accelerated parasite detection, with a mean precision of 4·4%, specificity of 98·9% and accuracy of 101·3%. The detection and quantitation limits in the assay were 0·024% and 0·074% parasitaemia, respectively. Overall, the parasite counts by FCM measurement correlated highly (r2=0·954–0·988) with the parasitaemia measured by light microscopical analysis when animals treated with suppressive, clearance, and curative doses of novel antimalarial drugs were examined. The lower levels of parasitaemia (30%) detected by microscopy compared to FCM may be related to a number of schizonts externally attached to the erythrocyte membranes that normally would not be included in microscopy counting. Lower sampling error and reliable identification of rodent erythrocyte parasites based on the principles of FCM have replaced the traditional blood smear in our laboratory.
The clinical significance criterion in DSM-IV post-traumatic stress disorder
Authors: BRESLAU NAOMI , ALVARADO GERMAN F.
Published: April 2007

Background

The DSM-IV definition of post-traumatic stress disorder (PTSD) requires that the syndrome cause clinically significant distress or impairment. The impact of the clinical significance criterion on the lifetime prevalence of PTSD among civilian victims of traumatic events has not been evaluated.

Method

Data from two community-based samples were examined, the 1996 Detroit Area Survey of Trauma (n=2181) and the Mid-Atlantic Urban Youth Study (n=1698). The World Health Organization Composite International Diagnostic Interview (WHO CIDI) was used to ascertain DSM-IV PTSD.

Results

The inclusion of the clinical significance criterion in DSM-IV reduces the conditional probability of PTSD given exposure to trauma by approximately 30%. Cases with clinically significant syndrome showed more pervasive and persistent disturbance and an excess in impaired activity days.

Conclusions

The consistency of the findings between the two studies strengthens the evidence on the impact of the clinical significance criterion in the diagnosis of PTSD, and the construct validity of its measurement. There is a need for greater research effort on the definition and measurement of the clinical significance criterion.
Suicide and occupation: the impact of socio-economic, demographic and psychiatric differences
Authors: AGERBO ESBEN , GUNNELL DAVID , BONDE JENS PETER , BO MORTENSEN PREBEN , NORDENTOFT MERETE
Published: April 2007

Background

To explore the risk of suicide associated with occupation while evaluating the impact of socio-economic, demographic and psychiatric differences.

Method

A nested case–control study with 3195 suicides and 63 900 matched controls. Information on causes of death, occupation, psychiatric admission, marital status and socio-economic factors was obtained from routine registers.

Results

Across the 55 occupations investigated, the risk of suicide ranged from 2·73 [95% confidence interval (CI) 1·77–4·22] among doctors to 0·44 (95% CI 0·27–0·72) among architects and engineers compared with primary school teachers. With the exception of doctors and nurses, most of the excess risk of suicide associated with particular occupations is explained by the social and economic characteristics of people in those occupations. Much, but not all, of the excess risk in doctors and nurses is due to their increased use of self-poisoning, a method for which they have the knowledge to use effectively. Occupation has little association with suicide among people who suffer from a psychiatric illness, except for doctors, where the excess risk is 3·62 (p=0·007).

Conclusions

Most of the considerable variation in suicide risk across occupations is explained by socio-economic factors, except for doctors and nurses. Apart from in doctors, the risk of suicide has little association with occupation among people who suffer from a psychiatric illness. Restriction of access to lethal means is an important strategy in suicide prevention.
Longitudinal modeling of genetic and environmental influences on self-reported availability of psychoactive substances: alcohol, cigarettes, marijuana, cocaine and stimulants
Authors: GILLESPIE NATHAN A. , KENDLER KENNETH S. , PRESCOTT CAROL A. , AGGEN STEVEN H. , GARDNER CHARLES O. , JACOBSON KRISTEN , NEALE MICHAEL C.
Published: April 2007

Background. Although an obvious environmental factor influencing drug use, the sources of individual differences in drug availability (DA) are unknown.

Method. This report is based on 1788 adult males from the Mid-Atlantic Twin Registry who participated in a structured telephone interview that included retrospective assessments of DA (cigarette, alcohol, marijuana, cocaine and stimulants) between ages 8 and 25. We fitted a biometric dual change score (DCS) model, adapted for ordinal data, to model latent growth and estimate the genetic and environmental components of variance over time.

Results. DA, despite being considered an environmental risk factor, is under both genetic and environmental control. For cigarette, alcohol, marijuana and cocaine availability, there was an overall increase in additive genetic variance and a decline in shared environmental variance over time. Non-shared environmental variance remained steady. Stimulant availability did not follow this pattern. Instead, there was an upswing in shared environmental effects with increasing age.

Conclusion. We have modeled the genetic and environmental architecture of changes in DA across adolescence. The rise in additive genetic variance over time coincides with acceleration in the expression of individual differences, probably brought on by an increase in personal freedom and a reduction in social constraints. Understanding the etiology of DA is likely to reveal key components, acting directly or indirectly, in the pathway(s) leading to drug initiation, abuse and dependence.
What does it mean to call Karl Barth a ‘christocentric’ theologian?
Authors: Cortez Marc
Published: April 2007

Karl Barth's interpreters often characterize him as a ‘christocentric’ theologian. This term, however, is subject to a variety of interpretations, ranging from the totalitarian and isolationist critiques of the ‘christomonist’ objection to the indeterminate and decentred approaches offered by various postmodern readings. The disparity between these two approaches suggests a level of ambiguity in the term that hinders its usefulness unless carefully qualified. Indeed, ‘centric’ terminology itself remains rather ambiguous until the substantive formal and material considerations that lie behind any given form of centricity are addressed. This article proposes to alleviate the ambiguity that has thus clouded the use of ‘christocentric’ as a description of Barth's theology by offering five formal and material qualifications; Barth's christocentricity must be understood in terms of (1) a veiling and unveiling of knowledge in Christ, (2) a methodological orientation, (3) a particular christology, (4) a trinitarian focus and (5) an affirmation of creaturely reality. Using these criteria, the article also argues that both the christomonistic and postmodern interpretations break down at certain points because they fail to appreciate fully these qualifications and thus the particular nature of Barth's christocentrism.
‘Jesus is victor’: passing the impasse of Barth on universalism
Authors: Greggs Tom
Published: April 2007

This article examines the question of Karl Barth's stance on universalism. Setting the question within the wealth of contradictory accounts of Barth on this issue, it seeks to find a way through the opposing views represented in the secondary literature. Following a brief examination of the doctrine of election which is the source of the charge of universalism, Barth's response to Berkouwer's The Triumph of Grace in the Theology of Karl Barth will be considered in detail. This passage helps to place Barth's own reaction to the charge of universalism in a broader framework than that of a simple denial or acceptance, and helps to highlight what Barth does and does not reject regarding universalism. It will be argued that it is the replacement of the person of Jesus Christ with a principle, rather than any limitation of the salvific work of God, that Barth rejects in rejecting apokatastasis. Barth's denial of universalism marks a dismissal of the problematic elements associated with the word, not a denial of the ultimate friendliness of Jesus Christ. The radical newness of Barth's own approach to universalism cannot be overemphasized, and marks the means by which one may pass through the impasse of differing accounts of Barth's eschatology.
Single Frequency Multipath Mitigation Based On Wavelet Analysis
Authors: Aram Mohammad , El-Rabbany Ahmed , Krishnan Sri , Anpalagan Alagan
Published: April 2007

Multipath is still one of the major error sources that degrades the accuracy of GPS positioning. The amount of multipath is highly dependent on the antenna's environment, which makes it difficult to isolate. Usually there is at least one in-view satellite which is more susceptible to multipath, particularly the one with the lowest elevation angle. To increase the positioning the best satellites must be selected (i.e. by least square or multipath mitigation) for computing a position. In this paper we propose an algorithm which picks up the best satellites (when there are more than four satellites in view) based on wavelet analysis for calculating a position. In this experiment, code and carrier measurements were collected in 15-minute segments by exploiting a single frequency (L1), stationary, navigation-grade receiver in a high-multipath environment. The magnitudes of these pseudoranges were often inflated by multipath error. We then post-processed the received data by applying wavelet filtering to the residuals (code minus carrier) to approximate the multipath values, and compute the receiver's position based on the selected satellites. Satellites were selected based on the residual values. To compare the results with the raw measurements, statistical elements were computed. The results showed significant improvement in variance of the estimated positions and, most importantly, a normalization of the data scatter-distribution was observed.
DGPS Correction Prediction Using Artificial Neural Networks
Authors: Mohasseb M. , El-Rabbany A. , Abd El-Alim O. , Rashad R.
Published: April 2007

This paper focuses on modelling and predicting differential GPS corrections transmitted by marine radio-beacon systems using artificial neural networks. Various neural network structures with various training algorithms were examined, including Linear, Radial Biases, and Feedforward. Matlab Neural Network toolbox is used for this purpose. Data sets used in building the model are the transmitted pseudorange corrections and broadcast navigation message. Model design is passed through several stages, namely data collection, preprocessing, model building, and finally model validation. It is found that feedforward neural network with automated regularization is the most suitable for our data. In training the neural network, different approaches are used to take advantage of the pseudorange corrections history while taking into account the required time for prediction and storage limitations. Three data structures are considered in training the neural network, namely all round, compound, and average. Of the various data structures examined, it is found that the average data structure is the most suitable. It is shown that the developed model is capable of predicting the differential correction with an accuracy level comparable to that of beacon-transmitted real-time DGPS correction.
Chemical Plume Tracing and Odour Source Localisation by Autonomous Vehicles
Authors: Naeem W. , Sutton R. , Chudley J.
Published: April 2007

Autonomous vehicles with an ability to trace chemical plumes can be instrumental in tasks such as detection of unexploded ordnance, search for undersea wreckage and environmental monitoring. As a consequence, use of autonomous vehicles to perform chemical plume tracing has received an increasing interest from the research community in recent years. Owing to the diversity of applications and ambient fluid environment of the plumes, there are numerous plume tracing strategies and approaches. This paper reviews two main approaches and a number of strategies that have been successfully implemented to track air or water borne plumes in order to locate odour sources using autonomous vehicles. The first strategy considered is the biomimetic approach that offers excellent models for the development of robotic systems. Strategies inspired by lobsters and bacterium are the main focus in this study. The second scheme considers parallelization of the search procedure by employing a multi-robot approach. This approach has the advantage of utilising a group of smaller and simpler communicating robots which are capable of performing a collaborative search of the plume.
Failure Modes and Models for Integrated GPS/INS Systems
Authors: Bhatti Umar Iqbal , Ochieng Washington Yotto
Published: April 2007

GPS is the most widely used global navigation satellite system. By design, there is no provision for real time integrity information within the Standard Positioning Service (SPS). However, in safety critical sectors like aviation, stringent integrity performance requirements must be met. This can be achieved externally or at the receiver level through receiver autonomous integrity monitoring (RAIM). The latter is a cost effective method that relies on data consistency, and therefore requires redundant measurements. An external aid to provide this redundancy can be in the form of an Inertial Navigation System (INS). This should enable continued performance even during RAIM holes (when no redundant satellite measurements are available). However, due to the inclusion of an additional system and the coupling mechanism, integrity issues become more challenging. To develop an effective integrity monitoring capability, a good understanding of the potential failure modes of the integrated system is vital. In this paper potential failure modes of integrated GPS/INS systems are identified. This is followed by the specification of corresponding models that would be required to investigate the capability of existing integrity algorithms and to develop enhancements or new algorithms.
A mathematical model of the dynamics of Salmonella Cerro infection in a US dairy herd
Authors: CHAPAGAIN P. P. , VAN KESSEL J. S. , KARNS J. S. , WOLFGANG D. R. , HOVINGH E. , NELEN K. A. , SCHUKKEN Y. H. , GROHN Y. T.
Published: April 2007

We developed a mathematical model of the transmission dynamics of salmonella to describe an outbreak of S. Cerro infection that occurred in a Pennsylvania dairy herd. The data were collected as part of a cooperative research project between the Regional Dairy Quality Management Alliance and the Agricultural Research Service. After the initial detection of a high prevalence of S. Cerro infection in the herd, a frequent and intensive sampling was conducted and the outbreak was followed for 1 year. The data showed a persistent presence of S. Cerro with a high prevalence of infection in the herd. The dynamics of host and pathogen were modelled using a set of nonlinear differential equations. A more realistically distributed (gamma-distributed) infectious period using multiple stages of infection was considered. The basic reproduction number was calculated and relevance to the intervention strategies is discussed.
Outbreak of waterborne cryptosporidiosis associated with low oocyst concentrations
Authors: NEIRA-MUNOZ E. , OKORO C. , McCARTHY N. D.
Published: April 2007

Water treatment plants in the United Kingdom at significant risk of cryptosporidiosis and using conventional filtration methods have been required to install 24-h monitoring systems since April 2000. No major waterborne outbreaks have been described since 2001. Small outbreaks have been associated with water. This paper describes such an outbreak. Data from a local multi-agency surveillance system was used to describe the outbreak, including mapping cases against water supply zones. A case-control study investigated hypotheses raised. All cases were genotype 1. Early cases were in the supply zone of a surface water-treatment plant that had met treatment standards. Later cases included residents in a different supply zone that temporarily received water from the implicated plant. Cases reported more consumption of domestic mains water than controls. Descriptive and analytical epidemiology thus supported drinking water as a source of cryptosporidiosis from a plant meeting regulatory requirements. The evidence for setting drinking-water standards needs review.
Emerging zoonoses and vector-borne infections affecting humans in Europe
Authors: VOROU R. M. , PAPAVASSILIOU V. G. , TSIODRAS S.
Published: April 2007

The purpose of this study was to assess and describe the current spectrum of emerging zoonoses between 2000 and 2006 in European countries. A computerized search of the Medline database from January 1966 to August 2006 for all zoonotic agents in European countries was performed using specific criteria for emergence. Fifteen pathogens were identified as emerging in Europe from 2000 to August 2006:Rickettsiaespp.,Anaplasma phagocytophilum,Borrelia burgdorferi,Bartonellaspp.,Francisella tularensis, Crimean Congo Haemorrhagic Fever Virus,Hantavirus, Toscana virus, Tick-borne encephalitis virus group, West Nile virus, Sindbis virus, Highly Pathogenic Avian influenza, variant Creutzfeldt–Jakob disease,Trichinellaspp., andEchinococus multilocularis. Main risk factors included climatic variations, certain human activities as well as movements of animals, people or goods. Multi-disciplinary preventive strategies addressing these pathogens are of public health importance. Uniform harmonized case definitions should be introduced throughout Europe as true prevalence and incidence estimates are otherwise impossible.
Aneurysmal formation in the setting of muscular ventricular septal defects
Authors: Oztunc Funda , Demir Tevfik , Saltik Levent , Guzeltas Alper
Published: April 2007

Objective: To emphasize the formation of fibrous aneurysmal structures in the setting of muscular ventricular septal defects Methods: Among patients with muscular ventricular septal defects followed in our institute, we described six who were diagnosed with formation of fibrous aneurysms. Of the patients, one was female and others were male. The age at diagnosis ranged from eight days to 16 years. In one, the defect opened between the ventricular inlets, but in the others the defects occupied the middle part of the apical trabecular septum. Results: The sizes of defects at initial echocardiographic evaluation ranged from 2.9 to 8 millimetres. The period of follow up for four patients was from 5 months to 7 years, one patient could not be followed up, and the other had already been diagnosed when first seen in our Institution. In our second and third patients, no aneurysm was seen during the initial echocardiographic evaluation, and it was recognized during follow-up. In these two patients, sequential echocardiographic examinations showed that the formation of the aneurysm made the defect smaller, with it almost closing in one. Conclusion: Although seen most frequently in the setting of perimembranous defects, fibrous aneurysms can also form adjacent to, and reduce the size of, muscular ventricular septal defects.
Variants of theCFC1gene in patients with laterality defects associated with congenital cardiac disease
Authors: Selamet Tierney Elif Seda , Marans Zvi , Rutkin Melissa B. , Chung Wendy K.
Published: April 2007

Objectives:This study was designed to assess the frequency and types of genetic variants inCFC1in children with laterality disorders associated with cardiovascular involvement.Background:Laterality syndromes are estimated to comprise 3% of neonates with congenital cardiac disease. Genetic predisposition in some cases of laterality defects has been suggested by associated chromosomal anomalies and familial aggregation, often within consanguineous families, suggesting autosomal recessive inheritance. Mice with induced homozygous mutations incfc1, and heterozygousCFC1mutations in humans, have been associated with laterality defects.Methods:Direct sequence analysis of the coding sequence ofCFC1was performed in 42 subjects with laterality defects and congenital cardiac disease.Results:We identified 3 synonymous coding variants, 3 non-synonymous coding variants (N21H, R47Q, and R78W), and 2 intronic variants inCFC1. The N21H variant was observed in 3 of 19 affected Caucasians, and the R47Q variant in another 2. Neither polymorphism was observed in Caucasian controls. Furthermore, all subjects with the N21H polymorphism had double outlet right ventricle. Transmission of both the N21H and R47Q polymorphisms from unaffected parents was demonstrated, and all three non-synonymous variants had significant allele frequencies in unaffected African-American subjects, suggesting that other factors must also contribute to laterality defects.Conclusions:Three non-synonymous variants inCFC1were identified, the N21H variant being associated with laterality defects in Caucasians, but not fully penetrant. One or more of these non-synonymous missense variants may act as a susceptibility allele in conjunction with other genes, and/or environmental factors, to cause laterality defects.
Transcatheter closure of coronary arterial fistulas using the new Amplatzer® vascular plug
Authors: Fischer Gunther , Apostolopoulou Sotiria C. , Rammos Spyros , Kiaffas Maria , Kramer Hans Heiner
Published: April 2007

We report our initial experience in using the Amplatzer® vascular plug for closure of coronary arterial fistulas. The self-expanding, cylindrical, device is made from Nitinol wire mesh, and is available from 4 to 16 millimetres in diameter. We have now used the device to close fistulas in 3 patients, aged from 3 to 14 years, who presented with ratios of pulmonary-to-systemic flow from 1.5 to 3. In 2 patients, fistulas arising from the proximal right and left coronary arteries, with maximal diameters of 9 and 10 millimetres, respectively, had their narrowest diameter, of 6 millimetres, proximal to the entrance into the right atrium via a saccular aneurysm. The third fistula, with a maximal diameter of 16 millimetres, and with its origin from the circumflex coronary artery, entered the right atrium with nearly unrestricted flow, its narrowest diameter being 8 millimetres. For interventional closure, we chose plugs twice the diameter of the narrowest segment of the fistula, thus using 2 devices of 12 millimetres and one of 16 millimetres diameter. An arteriovenous loop was established through the fistula by snaring an exchange guide wire. Using a 7 or 8 French guide catheter inserted through the femoral vein, all plugs were placed at the narrowest segment of the fistula, leading to immediate complete closure of 2 fistulas. The third patient, with a fistula of the circumflex coronary artery, who received the largest plug initially had residual flow, but the fistula was found to be completely occluded at 12 months follow-up examination. We have demonstrated, therefore, safe and effective usage of the new vascular plug for transcatheter closure of moderate- to large-sized coronary arterial fistulas. The plug offers an alternative to cardiac surgery, or occlusion using coils.
Acquired stenosis of normally connected pulmonary veins
Authors: Chakrabarti Shanta , Mittal Ralph , Gnanapragasam James P , Martin Robin P.
Published: April 2007

Pulmonary venous stenosis has been a challenge to paediatric cardiologists and surgeons. In spite of significant improvements in the management and outcome of various congenital cardiac problems, the prognosis of this condition continues to be dismal. Acquired stenosis of the pulmonary veins has been described in the adult population, especially after radiofrequency ablation for atrial arrhythmias. The outcome of this condition has generally been described to be favourable in the long term. Acquisition of pulmonary venous stenosis in childhood has a very different outcome, and is not a very well recognised entity, with symptoms and signs which are non-specific. We present 7 infants who, when first assessed, had normal pulmonary veins, but who subsequently acquired stenoses of the veins, with very significant resultant morbidity and mortality.
Massive disturbance of the daytime lower ionosphere by the giant γ‐ray flare from magnetar SGR 1806–20
Authors: Inan U. S. , Lehtinen N. G. , Moore R. C. , Hurley K. , Boggs S. , Smith D. M. , Fishman G. J.
Published: April 2007

The giant γ‐ray flare from SGR 1806‐20 created a massive disturbance in the daytime lower ionosphere, as evidenced by unusually large changes in amplitude/phase of subionospherically propagating VLF signals. The perturbations of the 21.4 kHz NPM (Lualualei, Hawaii) signal observed at PA (Palmer Station, Antarctica) correspond to electron densities increasing by a factor of ∼100 to ∼103 cm−3 at ∼60 km and ≳1000 to ∼10 cm−3 at ∼30 km altitude. Enhanced conductivity produced by flare onset endured for >1 hour, the time scale determined by mutual neutralization. A brief (∼100 ms) low frequency (∼3 to 6 kHz) emission is also observed during the flare onset.
Space weather at Venus and its potential consequences for atmosphere evolution
Authors: Luhmann J. G. , Kasprzak W. T. , Russell C. T.
Published: April 2007

Space weather storms at the Earth are dominated by the magnetosphere's response to coronal mass ejections, or CMEs, whose disturbances propagate through the solar wind to 1 AU, and to a lesser extent by the pressure ridges associated with the interactions of solar wind streams with different properties. The interplanetary signatures of these events include high solar wind dynamic pressures and high interplanetary magnetic fields, the same parameters that cause compression and/or magnetization of the ionosphere at weakly magnetized Venus. The nature of Venus' response to these events is also expected to include increased atmosphere erosion by the solar wind interaction, a matter of potential interest for historical extrapolations of atmosphere escape. We consider the possible evidence for enhanced escape during these disturbances in the data from the Pioneer Venus Orbiter (PVO). Available magnetometer and plasma analyzer results are used to identify periods of interest and the interplanetary characteristics of the disturbed periods. It is found that the suprathermal (>36 eV) ion measurements from the Pioneer Venus neutral mass spectrometer (ONMS) provide convincing evidence of the related enhanced escape of mostly O+ suprathermal ions. The results provide the first direct demonstration that space weather has played an important role in Venus (and other weakly magnetized planet) atmosphere loss through time. It is important to pursue study of these effects with the new measurements from Venus Express and, in light of the approaching solar activity cycle rising phase, extremely timely.
Effect of temperature‐dependent organic carbon decay on atmospheric pCO2
Authors: Matsumoto Katsumi , Hashioka Taketo , Yamanaka Yasuhiro
Published: April 2007

Extendingy an almost universal observation that the rate of microbial activity increases with temperature, we propose that marine microbial activity was suppressed during previous glacial periods and allowed proportionally more organic carbon to be exported out of the surface ocean. A stronger organic carbon pump and therefore lower rain ratios of CaCO3 to organic carbon may have contributed to the low atmospheric CO2 content during the Last Glacial Maximum. Previous study of temperature‐dependent export production (Laws et al., 2000) and our map of data‐based, global distribution of the rain ratios lend support to today's rain ratios being controlled at least partly by temperature. A close examination with a high‐resolution regional ocean ecosystem model indicates that the correlation between rain ratio and temperature is caused indeed by preferential remineralization of organic matter, but a part of the correlation is also driven by temperature‐dependent community composition. An extrapolation of these results to the globe using a global carbon cycle box model with a module for sediments indicates that the drawdown of atmospheric CO2 by the proposed mechanism is approximately 30 ppm. While this estimate is subject to uncertainty, the fact that it represents nearly one third of the glacial‐interglacial variation in atmosphere pCO2 suggests the potential importance of the new mechanism. Given the historical difficulty in explaining the full CO2 amplitude with a single cause, we suggest that a set of multiple mechanisms were responsible and that the temperature‐dependent POC degradation rate is one of them. We discuss two possible difficulties with our proposal that have to do with the potentially important role that ballasts play in organic carbon export and the possibility that enhanced biological pump is self limiting.
Effect of Ga substitution on the structure and magnetic properties of melt-spun Pr3(Fe,Co,Ti)29 system
Authors: Sirisha K. , Chen Q. , Ma B. M. , Huang M.-Q. , Chen C. H. , McHenry M. E.
Published: April 2007

Melt-spun alloys of Pr3(Fe0.7Co0.3)27.5Ti1.5, Pr3(Fe0.6Co0.4)27.5Ti1.5, and Pr3(Fe0.5Ga0.1Co0.4)27.5Ti1.5 prepared at linear wheel speeds of 20, 30, and 40m∕s were found to contain nanocrystalline, a mixture of nanocrystalline and amorphous, and mostly amorphous phases, respectively. Grain sizes of <10nm were observed for the crystalline phases. Annealed alloys showed an increase in grain size to 15–20nm. The Curie temperature (TC) values observed in melt-spun alloys were lower than those observed in fully crystalline alloys. A reduction of ∼55°C in TC was observed for the Pr3(Fe0.7Co0.3)27.5Ti1.5 composition compared to ∼15°C for Pr3(Fe0.6Co0.4)27.5Ti1.5. For the Ga substituted alloy with Co=0.4, a large difference of ∼50°C in TC was noted. MS values of 41 and 35emu∕g were observed in alloys with Co=0.4 and Ga=0.1, and Co=0.4, respectively, at room temperature. Ga substitution increased the anisotropy field value, HA, but lowered the intrinsic coercivity value, Hci. In the alloys with Co=0.4 and Ga=0.1, and Co=0.4, spin reorientation transitions (TSR) were observed at 220 and 140K respectively. The low values of Hci observed in melt-spun ribbons are attributed to large amounts of a soft α-Fe phase.
Static and flowing regions in granular collapses down channels
Authors: Lube Gert , Huppert Herbert E. , Sparks R. Stephen J. , Freundt Armin
Published: April 2007

Through laboratory experiments we investigate inertial granular flows created by the instantaneous release of particulate columns into wide, rectangular channels. These flows are characterized by their unsteady motion, large changes of the free surface with time, and the propagation towards the free surface of an internal interface separating static and flowing regions. We present data for the time-dependent geometry of the internal interface and the upper, free surface for aspect ratios, a, in the range from 3 to 9.5 (where a=hi∕di is the ratio of the initial height to basal width of the column). The data were analyzed by two different approaches. First, by integrating under the entire internal interface we obtained data for the static area, AD, as a function of time for different a. Second, in order to characterize vertical deposition rates, we measured the thicknesses of the flowing region, hF(x,t), and the static region, hD(x,t), at fixed horizontal positions, x, and time, t, since the initiation of the experiment. We also determined detailed velocity profiles with depth at distances scaled to the final maximum runout distance to analyze the kinematic behavior of the flowing layer. In the initial free-fall phase, the temporal variation of the static area is independent of hi and scales as gdit. During the subsequent lateral spreading phase, AD(t) varies linearly with time and the nondimensional deposition rate (dAD∕dt)∕(gdi3)1∕2 is a linear function of a. The thickness of the interface hD(x,t) at constant x depends on a and varies linearly with time. The local deposition rate ∂hD∕∂t is not constant along the flow length. Data show that for the major part of the flow length ∂2hD∕∂t∂x is constant. In the lateral spreading phase, the velocity profiles are characteristically linear with a basal exponential region, a few grains in thickness, which separates static from moving regions. The shear rate is a constant dependent on a modified initial height h̃i as (g∕h̃i)1∕2, where h̃i is a characteristic length scale in the system describing the fraction of the granular column actually involved in the flowing region.
Lyapunov exponents for unitary Anderson models
Authors: Hamza Eman , Stolz Günter
Published: April 2007

We study a unitary version of the one-dimensional Anderson model, given by a five diagonal deterministic unitary operator multiplicatively perturbed by a random phase matrix. We fully characterize positivity and vanishing of the Lyapunov exponent for this model throughout the spectrum and for arbitrary distributions of the random phases. This includes Bernoulli distributions, where in certain cases a finite number of critical spectral values, with vanishing Lyapunov exponent, exist. We establish similar results for a unitary version of the random dimer model.
Linear and nonlinear development of oblique beam-plasma instabilities in the relativistic kinetic regime
Authors: Gremillet L. , Bénisti D. , Lefebvre E. , Bret A.
Published: April 2007

Collisionless beam-plasma instabilities are expected to play a crucial role during the early phase of the relativistic electron transport in the Fast Ignition scheme. This Letter presents a theoretical study of these instabilities in a two-dimensional geometry, highlighting the role of unstable modes propagating obliquely to the beam direction. The main features identified through a linearized analysis in a very general kinetic framework are examined by means of a particle-in-cell simulation. Good agreement between the two approaches is observed in the linear phase. Beam trapping is found to account for the nonlinear wave saturation.
Quantum study on the branching ratio of the reaction NO2+OH
Authors: Williams Christopher F. , Pogrebnya Sergei K. , Clary David C.
Published: April 2007

A reduced dimensionality (RD) approximation is developed for the title reaction which treats the angle of approach of the hydroxyl radical to the nitrogen dioxide molecule and the radial distance between the two species explicitly. All other degrees of freedom are treated adiabatically. Electronic structure calculations at the complete active space self-consistent field level are used to fit a potential energy surface (PES) in these two coordinates. Within this RD model the adiabatic capture centrifugal sudden approximation is used to calculate the high pressure limit rate constant. A correction for reflection from the PES due to rotationally nonadiabatic transitions is applied using the wave packet capture approximation. The branching ratio for the title reaction is calculated for the atmospherically significant temperature range of 200–400K at 20Torr without distinguishing between the conformers of HOONO. The result is kHOONO∕kHNO3=0.051 at 20Torr and 300K, which is in good agreement with the measured branching ratio between cis-cis-HOONO and nitric acid. This suggests that most of the different conformers of HOONO were converted to the most stable cis-cis conformer on the time scale of the measurements made.
Design of InxGa1−xAs1−yNy∕AlAs quantum cascade structures for 3.4μm intersubband emission
Authors: Dang Y. X. , Fan W. J.
Published: April 2007

We report the design of an active region of InxGa1−xAs1−yNy∕AlAs quantum cascade laser structure emitting in the near infrared wavelength range based on an eight-band k∙p model. The InxGa1−xAs1−yNy∕AlAs heterostructure system is of significant interest for the development of short wavelength quantum cascade lasers due to its large conduction band discontinuity (∼1.5eV) and compatibility with the mature GaAs fabrication process. A detailed analysis of the intersubband transition energy within the conduction band as a function of layer thickness, composition, electric field, and temperature has been carried out. Finally, an optimized combination of In0.2Ga0.8As0.97N0.03∕AlAs three-coupled-well structure has been obtained. Under an applied field of 100kV∕cm and at room temperature, a shortest wavelength of 3.4μm has been achieved by making use of this system without introducing an upper lasing level beyond the X minima of the AlAs barrier.