bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of umbilical ring constriction on Wharton's jelly
Authors: Skulstad S. M. , Ulriksen M. , Rasmussen S. , Kiserud T. 
Published: September 2006

AbstractObjectiveThe turgor of Wharton's jelly depends on osmotic and hydrostatic pressures. We tested the hypothesis that umbilical ring constriction has an impact on umbilical venous hemodynamics and thus on the volume of Wharton's jelly.MethodsIn a cross‐sectional study of 237 low‐risk singleton pregnancies, the cross‐sectional area of the fetal end of the umbilical cord was determined using sonography at 20–41 weeks of gestation. The inner area of the two arteries and the vein was also measured and subtracted from the cord area to calculate the area of Wharton's jelly. Based on the Bernoulli equation, the degree of vein constriction at the umbilical ring was assessed using the blood velocity increment at the abdominal inlet. Regression analysis and SD‐score statistics were used to construct mean values and to assess the effects. The dataset was also analyzed for gender‐specific effects.ResultsThe umbilical cord cross‐sectional area increased with gestational age during the period 20–31 weeks, remaining essentially stable thereafter. The Wharton's jelly increased with gestational age from 20 until 31–32 weeks of gestation and remained at the same level for the rest of the pregnancy. At mid‐gestation, on average 70% of the cord cross‐sectional area was occupied by Wharton's jelly; at 31 weeks and later this value was 60%. Umbilical vein constriction was associated with reduced umbilical cord cross‐sectional area and Wharton's jelly in female fetuses (P = 0.0007 and P = 0.003, respectively), but not in male fetuses.ConclusionsUnder physiological conditions, umbilical ring constriction affects umbilical vein hemodynamics, with corresponding effects on the umbilical cord cross‐sectional area and the amount of Wharton's jelly. Interestingly, the effects are gender‐specific. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.
Timely diagnosis of twin‐to‐twin transfusion syndrome in monochorionic twin pregnancies by biweekly sonography combined with patient instruction to report onset of symptoms
Authors: Sueters M. , Middeldorp J. M. , Lopriore E. , Oepkes D. , Kanhai H. H. H. , Vandenbussche F. P. H. A. 
Published: September 2006

AbstractObjectivesTo assess the value of serial ultrasound examinations together with patient instructions to report the onset of symptoms in achieving timely detection of twin‐to‐twin transfusion syndrome (TTTS) in a cohort of monochorionic diamniotic twin pregnancies, and to evaluate sonographic TTTS predictors.MethodsTimely detection of TTTS was defined as diagnosis before severe complications of TTTS occurred, such as preterm prelabor rupture of membranes, very preterm delivery (24–32 weeks of pregnancy), fetal hydrops, or intrauterine fetal death. During a 2‐year period, a prospective series of 23 monochorionic twin pregnancies was monitored from the first trimester until delivery. At least every 2 weeks we performed ultrasound and Doppler measurements (nuchal translucency thickness, presence of membrane folding, estimated fetal weight, deepest vertical pocket, bladder filling, and Doppler waveforms of the umbilical artery, ductus venosus and umbilical vein). Measurements of TTTS cases were compared with those of non‐TTTS cases matched for gestational age. Furthermore, patients were informed about the symptoms caused by TTTS, and instructed to consult us immediately in case of rapidly increasing abdominal size or premature contractions.ResultsIn all four TTTS cases, the diagnosis was timely. At the time of diagnosis, one case was at Quintero Stage 1, two at Quintero Stage 2, and one at Quintero Stage 3. Two of the TTTS cases became apparent after the patients' feeling of rapidly increasing girth. The identification of TTTS predictors was successful with respect to one parameter: isolated polyhydramnios in one sac, without oligohydramnios in the other, preceded the ultimate diagnosis of TTTS in two of the four TTTS cases. All other ultrasound measurements of TTTS cases, prior to the diagnosis of TTTS, were within the range of measurements of non‐TTTS cases.ConclusionBiweekly ultrasound examinations, with special attention to the amniotic fluid compartments of both fetuses, combined with detailed patient instructions to report the onset of symptoms resulted in timely diagnosis of all TTTS cases and appears to be a safe program for monitoring monochorionic twin pregnancies. Copyright © 2006 ISUOG. Published by John Wiley & Sons, Ltd.
Generation of bivariate Nakagami‐m fading envelopes with arbitrary not necessary identical fading parameters
Authors: Reig J. , Martinez‐Amoraga M. A. , Rubio L. 
Published: September 2006

AbstractIn this paper, a generation procedure of two correlated Nakagami‐m random variables for arbitrary fading parameters values (not necessary identical) is described. For the generation of two correlated Nakagami‐m samples, the proposed method uses the generalized Rice distribution, which appears in the conditional distribution of two correlated Nakagami‐m variables. This procedure can be applied to simulate diversity systems such as selection combiners, equal‐gain combiners, and maximal‐ratio combiners as well as multiple‐input multiple‐output (MIMO) receiver systems, in Nakagami‐m channels. Copyright © 2006 John Wiley & Sons, Ltd.
An approximation and its applications in wireless networks performance analysis
Authors: Zhang Yan , Fujise Masayuki 
Published: September 2006

AbstractIn the literature, there are two common assumptions for the tele‐traffic parameter in analyzing the wireless network performance, that is, the tele‐parameter follows a specific probability density function (pdf) and additionally the pdf exists closed‐form Laplace Transform (LT). However, taking into account the cell irregular shape, the specific pdf may be unavailable while only the measured statistical moments are available. Moreover, the pdf function may not exist a closed‐form LT, for example, lognormal distribution function. In this paper, based on the Central Limit Theorem and hyper‐Erlang universal approximation property, we propose an approximation method applicable in the situations when only the statistical moments are available or LT of pdf does not exist. We then employ the technique in diverse applications, including the performance analysis of wireless network and the cost evaluation of mobility management. Extensive numerical examples demonstrate the good approximation capability to the exact formula and the simulation results. Copyright © 2006 John Wiley & Sons, Ltd.
Enhancing channel utilization by improving media access coordination in wireless local area networks
Authors: Meerja Khalim Amjad , Shami Abdallah 
Published: September 2006

AbstractDistributed coordination function (DCF) is the basis protocol for IEEE 802.11 standard wireless local area networks. It is based on carrier sense multiple access with collision avoidance (CSMA/CA) mechanism. DCF uses backoff process to avoid collisions on the wireless channel. The main drawback with this process is that packets have to spend time in the backoff process which is an additional overhead in their transmission time. The channel is rendered idle when all the stations defer their transmissions due to their backoff process. Therefore, the channel utilization and the total throughput on the channel can be improved by reducing the average time spent by the packets in the backoff process. In this paper, we propose a new media access coordination function called proposed media access protocol (PMAP) that will improve the channel utilization for successful packet transmission and therefore, the total achievable throughput. In addition, we propose an analytical model for PMAP under saturated conditions. We use this model to analyze the performance of PMAP under saturated conditions. To substantiate the effectiveness of our model, we have verified the model by simulating PMAP in NS‐2. Simulation and analytical results show that under saturated conditions, PMAP shows profound improvement in the throughput performance compared to DCF. In addition, the throughput performance of PMAP under unsaturated conditions is presented. We have also presented the delay performance of PMAP and DCF through simulation in both saturated and unsaturated conditions. Simulation results show that the average delay experienced by the packets is less in PMAP compared to DCF. Further, the variance in the packet delay is same for both PMAP and DCF protocols under unsaturated conditions. From the performance results obtained for PMAP under both saturated and unsaturated conditions, it can be concluded that PMAP is superior in performance compared to DCF. Copyright © 2006 John Wiley & Sons, Ltd.
The impact of data aggregation on the performance of wireless sensor networks
Authors: Akkaya Kemal , Demirbas Murat , Aygun R. Savas 
Published: September 2006

AbstractWith the increasing need for different energy saving mechanisms in Wireless Sensor Networks (WSNs), data aggregation techniques for reducing the number of data transmissions by eliminating redundant information have been studied as a significant research problem. These studies have shown that data aggregation in WSNs may produce various trade‐offs among some network related performance metrics such as energy, latency, accuracy, fault‐tolerance and security. In this paper, we investigate the impact of data aggregation on these networking metrics by surveying the existing data aggregation protocols in WSNs. Our aim is twofold: First, providing a comprehensive summary and comparison of the existing data aggregation techniques with respect to different networking metrics. Second, pointing out both the possible future research issues and the need for collaboration between data management and networking research communities working on data aggregation in WSNs. Copyright © 2006 John Wiley & Sons, Ltd.
Evaluation and optimisation of session setup delay for streaming services over 3G networks with quality of service support
Authors: Viamonte David , Calveras Anna , Paradells Josep , Gómez Carles 
Published: September 2006

AbstractSession setup delay in Packet Switched Streaming (PSS) services over Third Generation (3G) wireless networks is impacted by Real‐Time Streaming Protocol (RTSP) and Session Description Protocol (SDP) signalling exchange and negotiation, as well as media buffering at the terminal before playback. The paper discusses PSS session setup delay over 3G, and proposes two RTSP and SDP protocol extensions to reduce this delay, namely: RTSP Early Setup and usage of SDP Templates. The rationale behind this proposal is presented, particularly when a Secondary Packed Data Protocol Context (PDP‐Context) is used to support media delivery with Quality of Service (QoS) support. The RTSP Early Setup mechanism facilitates pipelining of RTSP messages and early trigger of Secondary PDP‐Context setup. The SDP Template mechanism proposes using a generic procedure to avoid transmission of frequently used SDP fields. Copyright © 2006 John Wiley & Sons, Ltd.
Gibberellic‐acid‐induced reorientation of cortical microtubules in living plant cells
Authors: LLOYD C. W. , SHAW P. J. , WARN R. M. , YUAN M. 
Published: September 2006

By microinjecting rhodamine‐conjugated porcine tubulin into pea epidermis we recently showed how cortical microtubules reorientate from transverse to longitudinal in living cells (Yuan et al., 1994, Proc. Nat. Acad. Sci, USA91, 6050–6053). In the present paper we compare this reorientation with the contrary longitudinal to transverse realignment induced by adding gibberellic acid to pre‐injected cells on the microscope slide. Both kinds of reorientation are initiated by the appearance of ‘discordant’ microtubules which do not share the existing alignment but anticipate the new direction. These increase in number as the existing microtubules depolymerize, one alignment apparently replacing the other in a continuous process.By rotating stacks of confocal sections by computer methods we have previously shown that microtubules at the outer tangential cell wall do not necessarily have the same orientation as microtubules at the adjoining anticlinal walls of the same cell (Yuan et al., 1995, Plant J.7, 17–23). This suggests that microtubule reorientations in these epidermal cells occur mainly (or, at least, first) at the outer wall, indicating that the array may not reorientate as a whole. Collectively, these data emphasize the discontinuous nature of the realignment process, the importance of new microtubule polymerization, and the special property of the outer epidermal surface as a sensitive domain.
The MMPI‐2 Gender‐Masculine and Gender‐Feminine scales: Gender roles as predictors of psychological health in clinical patients
Authors: Woo Matthew , Oei Tian P. S. 
Published: September 2006

Previous research measuring various biosocial factors such as age, sex, and marital status has found them to be essentially unrelated to measures of psychological health. Recent empirical studies have revealed that personality constructs may be more significant than demographic variables in the prediction of psychological well‐being. The present study assessed the personality constructs of masculinity and femininity and hypothesized that the Gender‐Masculine (GM) scale of the MMPI‐2 would be more effective than the Gender‐Feminine (GF) scale in predicting psychological well‐being. This hypothesis stems from previous research that has indicated the dominance of the masculinity model. It is suggested that previous research supporting androgyny as a primary indicator of well‐being was influenced by the masculinity component of this gender orientation. One hundred and seventy‐seven psychiatric patients from Australia (N = 107) and Singapore (N = 70) completed the MMPI‐2. Hierarchical multiple regression revealed significantly stronger masculinity effects, with significance achieved on measures of ego strength and low self‐esteem. No significant relationship between psychological well‐being and the GF variable was found. Similarly, androgyny did not add any further variance to the model when masculinity was controlled for. Overall, the results are consistent with an interpretation that GM is a better correlate of psychological well‐being as compared to the GF scale.
A coastal vulnerability index and its application in Xiamen, China
Authors: Hong H. , Cui S. , Zhang L. 
Published: September 2006

With the increasing problems of global change, ecological security has become a research focus in the world. Coastal areas that are exposed to both human impact and natural changes are vulnerable. The maintenance of coastal ecological security is a great challenge. Assessment of vulnerability is essential for identifying and recognizing the coastal ecological security status. However, there is a lack of criteria and standards for vulnerability assessment.
We proposed a methodological framework of vulnerability analysis and assessment and used Xiamen city as a case study. Surveys were undertaken to assess the states of Xiamen coastal environment and resources, and the issues associated with human activities. Stakeholders were interviewed about their attitudes regarding Xiamen environment and resources. Constraints of development and management were identified. The methodological framework was presented as a tool to help identify relative vulnerability in order to prioritize actions and assess the vulnerability implications of management and policy decisions.
Climate agreements and technology spillovers—a modeling approach
Authors: Golombek Rolf , Hoel Michael 
Published: September 2006

A significant reduction in global greenhouse gas emissions will require development of new technologies if such reductions are to be achieved without excessive costs. An important question is whether an agreement of the Kyoto type, which does not include elements related to research and development of new technologies, will give sufficient incentives to develop such new technologies. On the one hand, since greenhouse gas emissions will become costly for countries and private producers, there will then be incentives to undertake the effort and costs to develop new technologies. On the other hand, research and development in one country is not only advantageous for this country, but usually also for other countries. The reason for this is that producers in these countries will learn from the project in many cases; for example, through (informal) networks, journals, and, in some cases, through the import of goods from the country where the new technology is developed.
The purpose of this paper is to discuss properties of an international climate agreement of the Kyoto type, when research and development investments undertaken in one country are also beneficial for other countries. We examine whether a Kyoto type of agreement can provide the correct social amount of aggregate emissions, and research and development investments in new technologies. We argue that the outcome of a Kyoto type agreement will differ from the social optimum. In particular, for a given level of abatement a Kyoto type agreement provides too few investments relative to the social optimum.
Protein–RNA interactions: exploring binding patterns with a three-dimensional superposition analysis of high resolution structures
Authors: Morozova N. , Allers J. , Myers J. , Shamoo Y. 
Published: September 2006

AbstractMotivation: The recognition of specific RNA sequences and structures by proteins is critical to our understanding of RNA processing, gene expression and viral replication. The diversity of RNA structures suggests that RNA recognition is substantially different than that of DNA.Results: The atomic coordinates of 41 protein–RNA complexes have been used to probe composite nucleoside binding pockets that form the structural and chemical underpinnings of base recognition. Composite nucleoside binding pockets were constructed using three-dimensional superpositions of each RNA nucleoside. Unlike protein–DNA interactions which are dominated by accessibility, RNA recognition frequently occurs in non-canonical and single-strand-like structures that allow interactions to occur from a much wider set of geometries and make fuller use of unique base shapes and hydrogen-bonding ability. By constructing composites that include all van der Waals, hydrogen-bonding, stacking and general non-polar interactions made to a particular nucleoside, the strategies employed are made readily visible. Protein–RNA interactions can result in the formation of a glove-like tight binding pocket around RNA bases, but the size, shape and non-polar binding patterns differ between specific RNA bases. We show that adenine can be distinguished from guanine based on the size and shape of the binding pocket and steric exclusion of the guanine N2 exocyclic amino group. The unique shape and hydrogen-bonding pattern for each RNA base allow proteins to make specific interactions through a very small number of contacts, as few as two in some cases.Availability: The program ENTANGLE is available fromContact: shamoo@rice.edu
Support vector machine learning from heterogeneous data: an empirical analysis using protein sequence and structure
Authors: Lewis Darrin P. , Jebara Tony , Noble William Stafford 
Published: September 2006

AbstractMotivation: Drawing inferences from large, heterogeneous sets of biological data requires a theoretical framework that is capable of representing, e.g. DNA and protein sequences, protein structures, microarray expression data, various types of interaction networks, etc. Recently, a class of algorithms known as kernel methods has emerged as a powerful framework for combining diverse types of data. The support vector machine (SVM) algorithm is the most popular kernel method, due to its theoretical underpinnings and strong empirical performance on a wide variety of classification tasks. Furthermore, several recently described extensions allow the SVM to assign relative weights to various datasets, depending upon their utilities in performing a given classification task.Results: In this work, we empirically investigate the performance of the SVM on the task of inferring gene functional annotations from a combination of protein sequence and structure data. Our results suggest that the SVM is quite robust to noise in the input datasets. Consequently, in the presence of only two types of data, an SVM trained from an unweighted combination of datasets performs as well or better than a more sophisticated algorithm that assigns weights to individual data types. Indeed, for this simple case, we can demonstrate empirically that no solution is significantly better than the naive, unweighted average of the two datasets. On the other hand, when multiple noisy datasets are included in the experiment, then the naive approach fares worse than the weighted approach. Our results suggest that for many applications, a naive unweighted sum of kernels may be sufficient.Availability: Contact: noble@gs.washington.eduSupplementary information: Supplementary Data are available at Bioinformatics online.
SCAssign: a sparky extension for the NMR resonance assignment of aliphatic side-chains of uniformly 13C,15N-labeled large proteins
Authors: Zhang Lei , Yang Daiwen 
Published: September 2006

Abstract
Summary: SCAssign (side-chain assignment) is a Sparky extension written in Python to assist the NMR resonance assignment of aliphatic side-chains of uniformly 13C,15N-labled large proteins. It is based on a general strategy recently developed in our laboratory that makes use of 4D 13C,15N-edited NOESY, 3D MQ-(H)CCmHm-TOCSY, and prior backbone assignments. The program runs on all operating systems for which Sparky is available, and is easy to install, setup and use. Not only can it accelerate the assignment process, it also allows assignments of weak NOEs in 4D NOESY, which used to be very difficult with manual approach.
Availability: The program, in the form of source code, is provided as free download at . The website also contains installation guide, user manual and demonstrations recorded in Flash.
Contact: Bug reports, questions or comments should be sent to dbsydw@nus.edu.sg.