New dinoflagellate cyst species from the upper Callovian-lower Oxfordian Rigaudella aemula zone, Timor sea, northwestern Australia

Four new species of dinoflagellate cysts are described from Callovian to lower Oxfordian (Jurassic) sediments of the Timor Sea, northwestern Australia. These comprise Evansia? lacryma, Egmontodinium elongatum, Leptodinium? ancoralium, and Nannoceratopsis reticulata. They are rare to common constituents of the Rigaudella aemula dinoflagellate cyst Interval Zone, and may prove useful for regional biostratigraphic correlation. (c) 2005 Elsevier B.V. All rights reserved.

Design of compact directive ultra wideband antipodal antenna

In this paper, a novel design procedure for designing a compact UWB antipodal Vivaldi antenna is presented. The antenna operates over the UWB frequency, band from 3.1 to more than 10.6 GHz. Its measured far-field radiation is directive and its peak gain is 10.2 dBi in the specified band. The antenna pulse response shows negligible distortion, indicating that it can be useful in a precision ranging and imaging instrumentation. (c) 2006 Wiley Periodicals, Inc.

Selective approach for transperitoneal and extraperitoneal endoscopic nephrectomy in children

Purpose: From the experience of a large combined series of transperitoneal. (TP) and retroperitoneal (RP) endoscopic complete and partial nephroureterectornies in children, we present a logical selective endoscopic approach to benign renal pathology. Materials and Methods: During a 5-year period 122 complete nephrectomies and nephroureterectomies (bilateral 2, invisible ectopic 8) and 63 partial nephroureterectomies for duplex (52 upper, 8 lower) or singleton polar disease (xanthogranulomatous pyelonephritis 1, cyst 2) were performed. Of the partial nephrectomies, ureterectomy, bladder repair and lower moiety reimplantation were performed in 8. Patient age ranged from 2.7 months to 14 years (mean 2.9 years). Preoperative weight ranged from 2.7 to 98 kg (mean 12.3). The position of the renal remnant, the presence or absence of a refluxing ureter and the need for ureterectomy were the major determining factors affecting choice of endoscopic approach. Results: A total of 179 (96.7%) procedures were successfully completed endoscopically. The 6 open conversions (3.2%) occurred early in our experience. The operating time reflected the complexity of the excision and lower urinary reconstruction (lateral and posterior RP 25 to 145 minutes [mean 921) TP with ureterocelectomy and bladder neck repair 105 to 355 minutes [mean 153]. Hospital stay for RP and simple TP was 1.5 days (mean 1 to 4) and for complicated TP 2 to 8 days (mean 3.5). Conclusions: We suggest a posterior retroperitoneal approach with isolated renal excision without extended ureterectomy. The lateral retroperitoneal approach allows complete ureterectomy as well as better exposure to horseshoe and pelvic kidneys and, therefore, avoids exposure to intraperitoneal. structures. Finally, the transperitoneal approach is recommended when complete moiety excision with lower urinary reconstruction is anticipated.

Congenital cystic adenomatoid malformation of the lung: indications and timing of surgery

We review a single surgeon and surgical centre's experience with congenital cystic adenomatoid malformation of the lung (CCAML) in relation to clinical spectrum, operative experience, and postoperative course. A retrospective hospital record review was done on surgically treated cases of CCAML over a 10-year period, focusing on number with antenatal diagnosis, spectrum of postnatal presentation, type of surgery performed, and outcome. Forty-seven patients from birth to 14 years of age underwent surgery for CCAML. Antenatal diagnosis (ante) was made in 30 cases. Of these, 10 became symptomatic before surgery. Six of the 17 postnatally-diagnosed (pnd) cases were an asymptomatic incidental finding. Overall, 16 were symptomatic in the 1st year of life, and five were symptomatic beyond 1 year of age. Symptoms varied from respiratory distress (seven ante, six pnd) to chronic cough (three, and recurrent chest infection (three ante, two pnd). All preoperative diagnoses were confirmed with chest CT. Most patients (25) were operated on before 3 months of age. Eleven were operated on in the first 2 weeks of life as emergency surgery for respiratory distress. The most common lobe involved was the right upper lobe (16), and lobectomy was performed in 42 cases, segmentectomy in four, and pneumonectomy in one. Seventeen cases were extubated immediately postoperatively; 29 required postoperative ventilation overnight, and nine needed more prolonged ventilation. Early postoperative complications included pneumothorax (two), pleural effusion (one), and chylous effusion (one). Late complications included recurrence in three cases (all segmentectomy), who then subsequently underwent lobectomy. There was one death from respiratory failure. Because there is an increasing trend in the detection of asymptomatic antenatally-diagnosed CCAML, consideration of early surgical excision to prevent complications is suggested by our series. CT scanning is mandatory for postnatal evaluation because chest x-ray could be normal. Safe elective excision after 3 months is supported by our low morbidity and less need for postoperative ventilation. Lobectomy is the procedure of choice to prevent recurrence.

Transmission dynamics of the Echinococcus granulosus sheep-dog strain (G1 genotype) in camels in Tunisia

Cystic echinococcosis, caused by Echinococcus grantilosus, is highly endemic in North Africa and the Middle East. This paper examines the abundance and prevalence of infection of E. granulosus in camels in Tunisia. No cysts were found in 103 camels from Kebili, whilst 19 of 188 camels from Benguerden (10.1%) were infected. Of the cysts found 95% were considered fertile with the presence of protoscolices and 80% of protoscolices were considered viable by their ability to exclude aqueous eosin. Molecular techniques were used on cyst material from camels and this demonstrated that the study animals were infected with the G1 sheep strain of E. granulosus. Observed data were fitted to a mathematical model by maximum likelihood techniques to define the parameters and their confidence limits and the negative binomial distribution was used to define the error variance in the observed data. The infection pressure to camels was somewhat lower in comparison to sheep reported in an earlier study. However, because camels are much longer-lived animals, the results of the model fit suggested that older camels have a relatively high prevalence rate, reaching a most likely value of 32% at age 15 years. This could represent an important source of transmission to dogs and hence indirectly to man of this zonotic strain. In common with similar studies on other species, there was no evidence of parasite-induced immunity in camels. (C) 2004 Elsevier B.V. All rights reserved.

Benign epithelial ovarian tumours - cancer precursors or markers for ovarian cancer risk?

The natural history of the development of epithelial ovarian cancer remains obscure and no effective screening test exists. In several human malignancies progression from benign to invasive tumour occurs, but this sequence has not been established for epithelial ovarian cancer. We have reviewed epidemiological, histopathological and molecular studies of benign epithelial ovarian tumours to assess the evidence for and against such a progression in ovarian cancer. These data suggest that a diagnosis of a benign ovarian cyst or tumour is associated with an increased risk of ovarian cancer later in life. Current evidence also suggests that benign serous tumours can progress to low-grade serous cancer and that benign mucinous tumours can progress to mucinous cancer. The more common high-grade serous ovarian cancers are likely to arise de novo.

Multiple-acquisition parallel imaging combined with a transceive array for the amelioration of high-field RF distortion: a modeling study

A new method for ameliorating high-field image distortion caused by radio frequency/tissue interaction is presented and modeled, The proposed method uses, but is not restricted to, a shielded four-element transceive phased array coil and involves performing two separate scans of the same slice with each scan using different excitations during transmission. By optimizing the amplitudes and phases for each scan, antipodal signal profiles can be obtained, and by combining both images together, the image distortion can be reduced several-fold. A hybrid finite-difference time-domain/method-of-moments method is used to theoretically demonstrate the method and also to predict the radio frequency behavior inside the human head. in addition, the proposed method is used in conjunction with the GRAPPA reconstruction technique to enable rapid imaging. Simulation results reported herein for IIT (470 MHz) brain imaging applications demonstrate the feasibility of the concept where multiple acquisitions using parallel imaging elements with GRAPPA reconstruction results in improved image quality. (c) 2006 Wiley Periodicals, Inc.

High-field magnetic resonance imaging with reduced field/tissue RF artefacts - A modeling study using hybrid MoM/FEM and FDTD technique

Due to complex field/tissue interactions, high-field magnetic resonance (MR) images suffer significant image distortions that result in compromised diagnostic quality. A new method that attempts to remove these distortions is proposed in this paper and is based on the use of transceiver-phased arrays. The proposed system uses, in the examples presented herein, a shielded four-element transceive-phased array head coil and involves performing two separate scans of the same slice with each scan using different excitations during transmission. By optimizing the amplitudes and phases for each scan, antipodal signal profiles can be obtained, and by combining both the images together, the image distortion can be reduced several fold. A combined hybrid method of moments (MoM)/finite element method (FEM) and finite-difference time-domain (FDTD) technique is proposed and used to elucidate the concept of the new method and to accurately evaluate the electromagnetic field (EMF) in a human head model. In addition, the proposed method is used in conjunction with the generalized auto-calibrating partially parallel acquisitions (GRAPPA) reconstruction technique to enable rapid imaging of the two scans. Simulation results reported herein for 11-T (470-MHz) brain imaging applications show that the new method with GRAPPA reconstruction theoretically results in improved image quality and that the proposed combined hybrid MoM/FEM and FDTD technique is. suitable for high-field magnetic resonance imaging (MRI) numerical analysis.