bluuebunny/crossref_metadata_2025_split huggingface dataset:
Giant omphaloceles with a small abdominal defect: prenatal diagnosis and neonatal management
Authors: Pelizzo G. , Maso G. , Dell'Oste C. , D'Ottavio G. , Bussani R. , Uxa F. , Conoscenti G. , Schleef J. 
Published: November 2005

AbstractA giant omphalocele is a liver‐containing protrusion through an abdominal defect wider than 5 cm in diameter. The giant form with a small abdominal wall defect is a rare condition which, to our knowledge, has not been described previously. We describe three cases with the typical features of elongated vascular liver pedicle and angiomatosis of the hepatic portal system. The abnormal liver organogenesis, due to extra‐abdominal development, represented a significant risk factor for hepatic thrombosis after visceral reduction and liver rotation. All the neonates underwent surgery on the first day of postnatal life. One died because of a postoperative liver infarction, and the survivors needed prolonged respiratory support. Prenatal sonographic features, timing, delivery, type of surgical repair, and postnatal outcome are reviewed. A prenatal sonographic diagnosis could be useful to evaluate the abdominal ring and serial ultrasound examinations are recommended to detect promptly ominous signs of hepatic and bowel damage. Color Doppler may be useful to assess the anatomy of the abdominal vessels and their relationships with the herniated organs, although it was not used in any of the cases reported here. This congenital malformation might be considered as a pathological entity separate from giant omphalocele with large abdominal defect, with a severe prognosis due possibly to its different embryological development. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.
Evaluation and validation of a new risk score (CLEOPATRA score) to predict the probability of premature delivery for patients with threatened preterm labor
Authors: Tekesin I. , Eberhart L. H. J. , Schaefer V. , Wallwiener D. , Schmidt S. 
Published: November 2005

AbstractObjectiveTo develop a clinically useful tool to predict the probability of preterm delivery in patients with threatened preterm labor.MethodsOne hundred and seventy patients with preterm labor between 24 and 34 weeks of gestation were included. Preterm delivery < 37 weeks of gestation was the main endpoint of the study. The data were randomized and split into an evaluation set (n = 85) and a validation set (n = 85). The evaluation set was subjected to stepwise backward logistic regression analysis to quantify the relative impact of four potential risk factors, including individual patient factors, results of a rapid fetal fibronectin assay, and sonographic measurement of cervical length. Using the constant of the logistic regression analysis and the beta‐coefficients for the identified risk factors the individual probability of preterm delivery for each woman of the validation dataset was calculated. The area under a receiver–operating characteristics curve (AUC) was used to evaluate the discriminating power of the score.ResultsThe overall rate of preterm delivery was 27.1%. The logistic regression analysis was performed for the potential predictors of spontaneous preterm delivery, identified by univariate analysis. These were positive fetal fibronectin, cervical length, previous preterm delivery and maternal age. Two risk factors were independent predictors of preterm delivery and were included in the CLEOPATRA I (clinical evaluation of preterm delivery and theoretical risk assessment) score: cervical length measurement and previous preterm delivery were associated with a higher risk of preterm delivery (odds ratio, 7.65 and 6.74, respectively). Since fetal fibronectin assay is not available at all institutions worldwide, it was excluded from the initial model. In the CLEOPATRA II model the risk factors fetal fibronectin and previous preterm delivery were associated with higher risk of preterm delivery, with odds ratios of 17.9 and 4.56, respectively. The discrimination power (AUC) obtained from the models were: CLEOPATRA I, 0.69 (95% CI, 0.56–0.82); CLEOPATRA II, 0.81 (95% CI, 0.69–0.93).ConclusionIn symptomatic women the risk for preterm delivery can be predicted best with the CLEOPATRA II score based on fetal fibronectin and previous preterm delivery. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.
Diagnostic accuracy of varying discriminatory zones for the prediction of ectopic pregnancy in women with a pregnancy of unknown location
Authors: Condous G. , Kirk E. , Lu C. , Van Huffel S. , Gevaert O. , De Moor B. , De Smet F. , Timmerman D. , Bourne T. 
Published: November 2005

AbstractObjectivesVarious serum human chorionic gonadotropin (hCG) discriminatory zones are currently used for evaluating the likelihood of an ectopic pregnancy in women classified as having a pregnancy of unknown location (PUL) following a transvaginal ultrasound examination. We evaluated the diagnostic accuracy of discriminatory zones for serum hCG levels of > 1000 IU/L, 1500 IU/L and 2000 IU/L for the detection of ectopic pregnancy in such women.MethodsThis was a prospective observational study of women who were assessed in a specialized transvaginal scanning unit. All women with a PUL had serum hCG measured at presentation. Expectant management of PULs was adopted. These women were followed up with transvaginal ultrasound, monitoring of serum hormone levels and laparoscopy until a final diagnosis was established: a failing PUL, an intrauterine pregnancy (IUP), an ectopic pregnancy or a persisting PUL. The persisting PULs probably represented ectopic pregnancies which had been missed on ultrasound and these were incorporated into the ectopic pregnancy group. Three different discriminatory zones (1000 IU/L, 1500 IU/L and 2000 IU/L) were evaluated for predicting ectopic pregnancy in this PUL population.ResultsA total of 5544 consecutive women presented to the early pregnancy unit between 25 June 2001 and 14 April 2003. Of these, 569 (10.3%) women were classified as having a PUL, 42 of which were lost to follow up. Of the 527 (9.5%) cases with PUL analyzed, there were 300 (56.9%) failing PULs, 181 (34.3%) IUPs and 46 (8.7%) ectopic pregnancies. Overall, 74.6% were symptomatic and 25.4% were asymptomatic (P = 8.825E–07). The sensitivity and specificity of an hCG level of > 1000 IU/L to detect ectopic pregnancy were 21.7% (10/46) and 87.3% (420/481), respectively; for an hCG level of > 1500 IU/L these values were 15.2% (7/46) and 93.4% (449/481), respectively, and for an hCG level of > 2000 IU/L they were 10.9% (5/46) and 95.2% (458/481), respectively.ConclusionsVarying the discriminatory zone does not significantly improve the detection of ectopic pregnancy in a PUL population. A single measurement of serum hCG is not only potentially falsely reassuring but also unhelpful in excluding the presence of an ectopic pregnancy. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.
Analysis of Z‐score distribution for the quality control of fetal ultrasound measurements at 20–24 weeks
Authors: Salomon L. J. , Bernard J. P. , Ville Y. 
Published: November 2005

AbstractObjectivesTo develop and evaluate the feasibility of Z‐score distribution‐based quality assessment for fetal biometry at 20–24 gestational weeks.MethodsFour sonographers measured fetal biparietal diameter, head circumference, abdominal circumference and femur length in unselected pregnancies undergoing routine sonography at 20–24 weeks in our center between June 2001 and January 2004. All measurements were transformed into Z‐scores. Distributions of Z‐scores were compared with the expected standard normal distribution based on mean, SD and the Kolmogorov–Smirnov test. Modelling was performed to assess the sensitivity, specificity and Youden's index (sensitivity + specificity − 1) of each sonographer, reflecting their ability to detect fetuses with abnormal biometry in our population.ResultsA total of 5241 ultrasound examinations were included. None of the Z‐score distributions could be considered similar to the standard normal distribution: means of Z‐scores ranged from −0.604 to 0.73 and the SD ranged from 0.726 to 0.896. Sensitivity and specificity ranged from 25.31% to 68.67% and 93.44% to 100%, respectively; Youden's index ranged from 0.25 to 0.69.ConclusionAnalysis of Z‐score distribution can be used to assess the quality of fetal measurements. Several indices can be extracted from this analysis in order to improve quality assessment of fetal biometry measured by ultrasound. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.
Three‐dimensional sonographic description of abnormal metopic suture in second‐ and third‐trimester fetuses
Authors: Chaoui R. , Levaillant J. M. , Benoit B. , Faro C. , Wegrzyn P. , Nicolaides K. H. 
Published: November 2005

AbstractObjectiveTo describe patterns of abnormal development of the metopic suture in association with fetal malformations during the second and third trimesters of pregnancy.MethodsThis was a cross‐sectional study of the frontal bones and metopic suture in 11 fetuses at 17–32 weeks of gestation. Cases were selected because there were obvious abnormalities in the metopic sutures. In each case, a malformation was detected by two‐dimensional (2D) ultrasound and the abnormality of the metopic suture was detected and evaluated on three‐dimensional (3D) ultrasound, using transparent maximum mode.ResultsThere were essentially four patterns of abnormality in the metopic suture: firstly, delayed development with a V‐ or Y‐shaped open suture, which is found in normal fetuses at 12–16 weeks; secondly, a U‐shaped open suture, presumably due to upward growth of the frontal bones with delayed closure; thirdly, premature closure of the suture, which is normally observed after 32 weeks; fourthly, the presence of additional bone between the frontal bones. Premature closure of the suture or additional bone between the frontal bones was observed in fetuses with holoprosencephaly and abnormalities of the corpus callosum, whereas the V‐, Y‐ and U‐shaped metopic sutures were observed in fetuses with facial defects involving the orbits, nasal bones, lip, palate and mandible, in the absence of holoprosencephaly and abnormal corpus callosum.ConclusionsThis preliminary study describes the pattern of possible abnormalities of the metopic suture and should stimulate further investigation to establish the prevalence and evolution of abnormal sutures as well as the incidence and pattern of other associated defects. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.
Assessment of lung area in normal fetuses at 12–32 weeks
Authors: Peralta C. F. A. , Cavoretto P. , Csapo B. , Vandecruys H. , Nicolaides K. H. 
Published: November 2005

AbstractObjectiveTo establish reference intervals with gestation for the right and left lung areas and lung area to head circumference ratio (LHR).MethodsThis was a cross‐sectional study of 650 normal singleton pregnancies at 12–32 weeks of gestation. We measured the left and right lung areas on the cross‐sectional plane of the thorax, used for examination of the four‐chamber view of the heart, by three different techniques: firstly, manual tracing of the limits of the lungs; secondly, multiplication of the longest diameter of the lung by its longest perpendicular diameter; thirdly, multiplication of the anteroposterior diameter of the lung at the mid‐clavicular line by the perpendicular diameter at the midpoint of the anteroposterior diameter.ResultsThe respective mean left and right lung areas (manual tracing) increased with gestational age, from 36 and 58 mm2 at 12 weeks to 220 and 325 mm2 at 20 weeks and 594 and 885 mm2 at 32 weeks. This 16‐fold increase in lung area was accompanied by a four‐fold increase in head circumference. Consequently, the left and right LHR increased with gestational age. The most reproducible way of measuring the lung area was by manual tracing of the limits of the lungs and the least reproducible was by multiplying the longest diameter of the lungs by their longest perpendicular diameter. Furthermore, the method employing the longest diameter, compared with the tracing method, overestimated both the left and the right lung areas by about 45% and the method employing the anteroposterior diameter overestimated the area of the right lung by about 35%, but not that of the left lung.ConclusionsIn the antenatal prediction of pulmonary hypoplasia by the assessment of lung area it is important to take gestational age into account. Dividing the lung area by the head circumference does not correct for the gestation‐related increase in lung area. Reproducible measurement of the lung area is provided by manual tracing of the limits of the lungs, rather than by multiplication of lung diameters. Copyright © 2005 ISUOG. Published by John Wiley & Sons, Ltd.
Performance evaluation of wireless cellular networks under more realistic assumptions
Authors: Fang Yuguang 
Published: November 2005

AbstractIn wireless cellular networks, performance evaluation is an important part in modeling and designing effective schemes to utilize the limited resource. In the past, performance evaluation was carried out either under restricted assumption on some time variables such as exponential assumption or via simulations. In this paper, we present a survey on a new analytical approach we have developed in the last few years to evaluate the performance of wireless cellular networks under more realistic assumptions. In particular, we apply this approach to the analysis of call connection performance and mobility management under assumptions that many time variables such as call holding time, cell residence time, channel holding time, registration area (RA) residence time, and inter‐service time are assumed to be generally distributed and show how we can obtain more general analytical results. Copyright © 2005 John Wiley & Sons, Ltd.
QoS‐aware mobility support architecture for next generation mobile networks
Authors: Jamalipour Abbas , Mirchandani Vinod , Kibria M. Rubaiyat 
Published: November 2005

AbstractProvision of quality of service (QoS) support with mobility has received impetus from the evolution that has occurred in mobile communication technologies. This is especially the main driver behind 4G/B3G networks that will enable a user to access any type of services anytime, anywhere, and anyhow. In this paper, we first review some of the state‐of‐the‐art techniques in the area of QoS and resource management based mobility. We then propose an augmented 4G/B3G architecture that addresses key limitations in the salient 4G architectures examined in the literature. Our proposed novel augmentations in mobility, QoS, and resource management schemes consolidate operation of the 4G architecture. The other defining attributes of our proposed 4G architecture are that it is open, hierarchical, layered, and modular with cross‐layer coordination and distributed network functionalities. Well‐defined message interfaces enable the layers/levels within the architecture to support cross‐layer coordination under dynamic network conditions. A signaling network that operates independent of the heterogeneous access networks in the architecture is incorporated to carry out wireless system discovery and paging. This facilitates to conserve mobile terminal's battery power. Copyright © 2005 John Wiley & Sons, Ltd.
NCTUns network simulation and emulation for wireless resource management
Authors: Wang Shie‐Yuan , Lin Yi‐Bing 
Published: November 2005

AbstractThis paper describes NCTUns, an innovative network simulator and emulator for wireless and mobile networks. Effects of various radio resource management and quality of service (QoS) schemes on higher‐layer protocols and real‐world applications can be easily studied using NCTUns. In this paper, we elaborate on NCTUns simulation methodology, architecture, design, functionalities, performance, and applications. NCTUns simulation for wireless ad hoc, sensor, inter‐vehicle communication networks, GPRS cellular networks, and wireless mesh networks are also illustrated. More details about this tool can be found in http://NSL.csie.nctu.edu.tw/nctuns.html. Copyright © 2005 John Wiley & Sons, Ltd.
Performance analysis of Bluetooth piconets with finite baseband buffers
Authors: Mišić Jelena , Mišić Vojislav B. 
Published: November 2005

AbstractWe analyze the performance of Bluetooth piconets under bursty traffic and finite buffer sizes. We model the joint probability distributions of uplink and downlink queues using theM[x]/G/1/Kmodel with vacations and derive buffer blocking probabilities at slaves and at the master. The results, which are confirmed through simulations, provide some practical guidelines as to the sizing of device buffers. Copyright © 2005 John Wiley & Sons, Ltd.
On greedy construction of connected dominating sets in wireless networks
Authors: Li Yingshu , Thai My T. , Wang Feng , Yi Chih‐Wei , Wan Peng‐Jun , Du Ding‐Zhu 
Published: November 2005

AbstractSince no fixed infrastructure and no centralized management present in wireless networks, a connected dominating set (CDS) of the graph representing the network is widely used as a virtual backbone. Constructing a minimum CDS is NP‐hard. In this paper, we propose a new greedy algorithm, called S‐MIS, with the help of Steiner tree that can construct a CDS within a factor of 4.8 + ln5 from the optimal solution. We also introduce the distributed version of this algorithm. We prove that the proposed algorithm is better than the current best performance ratio which is 6.8. A simulation is conducted to compare S‐MIS with its variation which is rS‐MIS. The simulation shows that the sizes of the CDSs generated by S‐MIS and rS‐MIS are almost the same. Copyright © 2005 John Wiley & Sons, Ltd.
Interference‐aware routing and bandwidth allocation for QoS provisioning in multihop wireless networks
Authors: Tang Jian , Xue Guoliang , Chandler Christopher 
Published: November 2005

AbstractIn this paper, we study the bandwidth guaranteed routing and timeslot allocation (BANDRA) in TDMA‐based multihop wireless networks with dynamic traffic. We formally model BANDRA as an optimization problem and present an integer linear programming (ILP) formulation to provide optimal solutions. This problem turns out to be a hard problem because of the impact of interference. Therefore, we propose a two‐step scheme, i.e., seeking a path for routing first and then allocating bandwidth along the found path. We present two routing algorithms to compute interference‐optimal cost‐bounded paths. In addition, we present an optimal bandwidth allocation algorithm to allocate timeslots along the found paths for connection requests with unit bandwidth requirements. For the general case where the bandwidth requirement is larger than one, we present an effective heuristic algorithm. Our simulation results show that the average difference between solutions given by our efficient scheme and optimal ones in terms of call‐blocking ratio is only 7%. Compared with the shortest path routing, our interference‐aware routing algorithms combined with our bandwidth allocation algorithm always reduce call‐blocking ratios. Copyright © 2005 John Wiley & Sons, Ltd.
Saturation throughput analysis of error‐prone 802.11 wireless networks
Authors: Ni Qiang , Li Tianji , Turletti Thierry , Xiao Yang 
Published: November 2005

AbstractIt is well known that the medium access control (MAC) layer is the main bottleneck for the IEEE 802.11 wireless LANs. Much work has been done on performance analysis of the 802.11 MAC. However, most of them assume that the wireless channel is error free. In this paper, we investigate the saturation throughput performance achieved at the MAC layer, in both congested and error‐prone channels. We provide a simple and accurate analytical model to calculate the MAC throughput. The model is validated through extensive simulation results. Our results show that channel errors have a significant impact on the system performance. Copyright © 2005 John Wiley & Sons, Ltd.
QoS provisioning in wireless networks
Authors: Wu Dapeng 
Published: November 2005

AbstractThe next‐generation wireless networks such as the fourth generation (4G) cellular systems are targeted at supporting various applications such as voice, data, and multimedia over packet‐switched networks. Providing quality of service (QoS) guarantees for these applications is an important objective in the design of the next‐generation wireless networks. In this paper, we overview the issues and techniques in QoS provisioning for wireless networks, and present some of our recent results in this area. Specifically, we survey the results in five sub‐areas, namely, network services models, traffic specification, packet scheduling for wireless transmission, call admission control in wireless networks, and wireless channel characterization. For each sub‐area, we address the particular issues, review major approaches and mechanisms, and discuss the trade‐offs of the approaches. Copyright © 2005 John Wiley & Sons, Ltd.
Resource management and QoS control in multiple traffic wireless and mobile Internet systems
Authors: Xu Yong , Liu Huazhou , Zeng Qing‐An 
Published: November 2005

AbstractEnd‐to‐end quality of service (QoS) control for multiple traffic in wired networks is carried out through Differentiated services (DiffServ). Edge routers in DiffServ domain classify incoming flows into different per‐hop behavior (PHB) groups and give a policy‐based QoS guarantee to these behavior aggregates. As Internet extends into the wireless and mobile section, different traffic flows should be treated differently not only in wired core network, but also in wireless resource allocations. In this paper, we propose a preemptive priority handoff and adaptive resource allocation scheme. DiffServ PHB groups are mapped into different wireless and mobile QoS classes. Traffic flows are categorized into these classes in order to allow the system to allocate different bandwidth and make resource reservation according to their priorities. Higher priority traffic flows are permitted to preempt lower priority flows in service. Lower ones, on the contrary, can expand their bandwidth into areas reserved for higher priority traffic flows for better resource utilization. We use both analytical model and simulation to evaluate the system performance in terms of blocking probabilities, forced termination probabilities, and delay. The forced termination probability of high priority traffic flows can be decreased significantly by introducing the preemptive priority scheme. Therefore, this scheme can be used in wireless part of the system along with DiffServ to give further guarantee for low delay, low jitter, and low loss services to high priority services. Copyright © 2005 John Wiley & Sons, Ltd.
A channel‐aware adaptive control to the MAC protocol in rate adaptive wireless LANs
Authors: Zhu Yanfeng , Niu Zhisheng 
Published: November 2005

AbstractDue to the low efficiency of legacy IEEE 802.11 MAC protocol, it has been the main bottleneck of wireless local area networks (WLANs). In this paper, we focus on multi‐rate WLANs and propose an adaptive transmission control scheme, which adapts the transmission probability according to the number of active stations, transmission rates, and channel conditions. At first, an analytical model is built in terms of the proposed scheme to explore the throughput of the network. Then, by means of the characteristics of practical system, a heuristic algorithm is developed to approach the maximum throughput on‐line. Extensive numerical calculations and simulations based on NS‐2 are implemented to evaluate the performance of the proposed algorithm and the impact of inaccurate estimation of parameters. The results show that our algorithm outperforms the existing adaptive algorithms in imperfect channel, and insensitive to inaccurate estimation of parameters. Copyright © 2005 John Wiley & Sons, Ltd.