bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sonographic assessment of normal and abnormal patterns of fetal cerebral lamination
Authors: Pugash D. , Hendson G. , Dunham C. P. , Dewar K. , Money D. M. , Prayer D. 
Published: May 2012

ABSTRACTObjectivesPrenatal development of the brain is characterized by gestational age‐specific changes in the laminar structure of the brain parenchyma before 30 gestational weeks. Cerebral lamination patterns of normal fetal brain development have been described histologically, by postmortem in‐vitro magnetic resonance imaging (MRI) and by in‐vivo fetal MRI. The purpose of this study was to evaluate the sonographic appearance of laminar organization of the cerebral wall in normal and abnormal brain development.MethodsThis was a retrospective study of ultrasound findings in 92 normal fetuses and 68 fetuses with abnormal cerebral lamination patterns for gestational age, at 17–38 weeks' gestation. We investigated the visibility of the subplate zone relative to the intermediate zone and correlated characteristic sonographic findings of cerebral lamination with gestational age in order to evaluate transient structures.ResultsIn the normal cohort, the subplate zone–intermediate zone interface was identified as early as 17 weeks, and in all 57 fetuses examined up to 28 weeks. In all of these fetuses, the subplate zone appeared anechoic and the intermediate zone appeared homogeneously more echogenic than did the subplate zone. In the 22 fetuses between 28 and 34 weeks, there was a transition period when lamination disappeared in a variable fashion. The subplate zone–intermediate zone interface was not identified in any fetus after 34 weeks (n = 13). There were three patterns of abnormal cerebral lamination: (1) no normal laminar pattern before 28 weeks (n = 32), in association with severe ventriculomegaly, diffuse ischemia, microcephaly, teratogen exposure or lissencephaly; (2) focal disruption of lamination before 28 weeks (n = 24), associated with hemorrhage, porencephaly, stroke, migrational abnormalities, thanatophoric dysplasia, meningomyelocele or encephalocele; (3) increased prominence and echogenicity of the intermediate zone before 28 weeks and/or persistence of a laminar pattern beyond 33 weeks (n = 10), associated with Type 1 lissencephaly or CMV infection. There was a mixed focal/diffuse pattern in two fetuses. In CMV infection, the earliest indication of the infection was focal heterogeneity and increased echogenicity of the intermediate zone, which predated the development of microcephaly, ventriculomegaly and intracranial calcification.ConclusionsThe fetal subplate and intermediate zones can be demonstrated reliably on routine sonography before 28 weeks and disappear after 34 weeks. These findings represent normal gestational age‐dependent transient laminar patterns of cerebral development and are consistent with histological studies. Abnormal fetal cerebral lamination patterns for gestational age are also visible on sonography, and may indicate abnormal brain development. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.
Lesion size affects diagnostic performance of IOTA logistic regression models, IOTA simple rules and risk of malignancy index in discriminating between benign and malignant adnexal masses
Authors: Di Legge A. , Testa A. C. , Ameye L. , Van Calster B. , Lissoni A. A. , Leone F. P. G. , Savelli L. , Franchi D. , Czekierdowski A. , Trio D. , Van Holsbeke C. , Ferrazzi E. , Scambia G. , Timmerman D. , Valentin L. 
Published: May 2012

AbstractObjectivesTo estimate the ability to discriminate between benign and malignant adnexal masses of different size using: subjective assessment, two International Ovarian Tumor Analysis (IOTA) logistic regression models (LR1 and LR2), the IOTA simple rules and the risk of malignancy index (RMI).MethodsWe used a multicenter IOTA database of 2445 patients with at least one adnexal mass, i.e. the database previously used to prospectively validate the diagnostic performance of LR1 and LR2. The masses were categorized into three subgroups according to their largest diameter: small tumors (diameter < 4 cm; n = 396), medium‐sized tumors (diameter, 4–9.9 cm; n = 1457) and large tumors (diameter ≥ 10 cm, n = 592). Subjective assessment, LR1 and LR2, IOTA simple rules and the RMI were applied to each of the three groups. Sensitivity, specificity, positive and negative likelihood ratio (LR+, LR−), diagnostic odds ratio (DOR) and area under the receiver–operating characteristics curve (AUC) were used to describe diagnostic performance. A moving window technique was applied to estimate the effect of tumor size as a continuous variable on the AUC. The reference standard was the histological diagnosis of the surgically removed adnexal mass.ResultsThe frequency of invasive malignancy was 10% in small tumors, 19% in medium‐sized tumors and 40% in large tumors; 11% of the large tumors were borderline tumors vs 3% and 4%, respectively, of the small and medium‐sized tumors. The type of benign histology also differed among the three subgroups. For all methods, sensitivity with regard to malignancy was lowest in small tumors (56–84% vs 67–93% in medium‐sized tumors and 74–95% in large tumors) while specificity was lowest in large tumors (60–87%vs 83–95% in medium‐sized tumors and 83–96% in small tumors ). The DOR and the AUC value were highest in medium‐sized tumors and the AUC was largest in tumors with a largest diameter of 7–11 cm.ConclusionTumor size affects the performance of subjective assessment, LR1 and LR2, the IOTA simple rules and the RMI in discriminating correctly between benign and malignant adnexal masses. The likely explanation, at least in part, is the difference in histology among tumors of different size. Copyright © 2012 ISUOG. Published by John Wiley & Sons, Ltd.
First‐trimester combined screening for trisomy 21 with different combinations of placental growth factor, free β‐human chorionic gonadotropin and pregnancy‐associated plasma protein‐A
Authors: Kagan K. O. , Hoopmann M. , Abele H. , Alkier R. , Lüthgens K. 
Published: May 2012

AbstractObjectiveTo examine placental growth factor (PlGF) in euploid and trisomy 21 pregnancies at 11–13 weeks' gestation and to model the impact on first‐trimester combined screening.MethodsPlGF was measured in 509 (409 euploid and 100 trisomic) fetal serum samples derived from prospective first‐trimester combined screening for trisomy 21 at 11–13 weeks' gestation. The serum samples were stored at −80°C, following the measurement of free β‐human chorionic gonadotropin (β‐hCG) and pregnancy‐associated plasma protein‐A (PAPP‐A) levels, for median time spans of 0.9 and 4.1 years in the euploid and trisomy 21 pregnancies, respectively. The effect of additional PlGF measurement at the time of combined screening was investigated by simulating fetal nuchal translucency (NT) measurements and multiples of the median (MoM) values for PAPP‐A, free β‐hCG and PlGF for 20 000 euploid and 20 000 trisomy 21 pregnancies. Patient‐specific combined risks were calculated based on maternal age and fetal NT in addition to free β‐hCG, PAPP‐A and PlGF, PAPP‐A and PlGF or free β‐hCG and PlGF, and detection and false‐positive rates were calculated.ResultsMedian PlGF‐MoM was 1.0 (95% confidence interval (CI), 0.96–1.04) in euploid fetuses and significantly lower, at 0.73 (95% CI, 0.70–0.76), in trisomy‐21 fetuses (P < 0.0001). There was no significant dependency between PlGF‐MoM and either gestational age at the time of blood sampling (r = 0.087, P = 0.392) or sample storage time (r = 0.028, P = 0.785). Modeled detection and false‐positive rates for first‐trimester combined screening (based on maternal and gestational age, fetal NT and maternal serum biochemistry) without PlGF were 85% and 2.7% for a fixed risk cut‐off of 1:100. The addition of PlGF increased the detection rate to 87% and reduced the false‐positive rate to 2.6%. Screening by maternal age and fetal NT in combination with PlGF and PAPP‐A or in combination with PlGF and free β‐hCG provided detection rates of 82% and 79%, with false‐positive rates of 2.7% and 3.0%, respectively.ConclusionIn pregnancies with trisomy 21 PlGF is reduced. The impact on the overall screening performance for trisomy 21 is low and does not justify the measurement of PlGF solely for trisomy 21 screening. However, as PlGF is measured with the aim of assessing the risk for pre‐eclampsia, further improvement in screening for trisomy 21 can be considered as an added benefit.
The rank transformation—an easy and intuitive way to connect many nonparametric methods to their parametric counterparts for seamless teaching introductory statistics courses
Authors: Conover W. Jay 
Published: May 2012

AbstractThe rank transformation refers to replacing the data by their ranks, or average ranks in case of ties, prior to performing standard statistical procedures on the ranks. There are several forms of transforming the data to ranks. RT‐1 refers to ranking all of the data together, and giving the smallest observation the rank 1, the second smallest the rank 2, and so on. RT‐2 involves ranking data within subgroups only, and not comparing data across subgroups. RT‐3 involves re‐expressing the data prior to ranking, such as subtracting a sample mean or median from the data and taking an absolute value of the difference prior to ranking. RT‐4 describes situations where data are re‐expressed within subgroups, and then ranked within subgroups.The rank transformation is a convenient way to bridge the pedagogical gap between parametric and nonparametric methods in statistics. First present the classical statistical procedure, such as a t test or a correlation coefficient, and then perform the same operation on the ranks of the data instead of the data themselves. The resulting method is equivalent to the standard presentation of nonparametric methods, and is amenable to convenient use in computer software. Limitations of this method are also described. WIREs Comput Stat 2012 doi: 10.1002/wics.1216This article is categorized under:

Statistical and Graphical Methods of Data Analysis > Nonparametric Methods
Statistical and Graphical Methods of Data Analysis > Transformations
Feasibility and short‐term outcome of adjuvant FOLFOX after resection of colorectal liver metastases
Authors: Sakamoto Yasuo , Beppu Toru , Miyamoto Yuji , Okabe Hirohisa , Ida Satoshi , Imai Katsunori , Chikamoto Akira , Watanabe Masayuki , Takamori Hiroshi , Baba Hideo 
Published: May 2012

AbstractBackgroundThe role of adjuvant chemotherapy for stage IV colorectal cancer has so far been under‐investigated. The aim of this study was to assess the feasibility and short‐term outcome of adjuvant chemotherapy with the FOLFOX regimen following liver resection for patients with colorectal liver metastasis (CRLM).MethodsFrom May 2005 to September 2010, 86 patients with CRLM underwent hepatic resection in the Department of Gastroenterological Surgery, Graduate School of Medical Sciences, Kumamoto University. Of these patients, 24 received FOLFOX4 or modified FOLFOX6 as postoperative adjuvant chemotherapy.ResultsNineteen male and 5 female patients received adjuvant chemotherapy following liver resection. Twenty‐one (87.5 %) of these patients completed 6 cycles of adjuvant chemotherapy. Five patients required a dose reduction due to neutropenia, and the dose intensities of oxaliplatin and 5‐FU were 93.6 and 94.1 %, respectively. There were no severe adverse events from the treatments. The median follow‐up period was 48.4 months. Recurrences developed in 12 patients, and 3 patients died during the follow‐up period. The 3‐ and 5‐year disease‐free survival and overall survival were 51.6 and 45.1 % and 95.5 and 76.0 %, respectively.ConclusionsAdjuvant FOLFOX is feasible and might provide a good prognosis for CRLM patients who undergo liver resection.
Wakes behind a prolate spheroid in crossflow
Authors: El Khoury George K. , Andersson Helge I. , Pettersen Bjørnar 
Published: May 2012

AbstractViscous laminar flow past a prolate$(L/ d= 6)$spheroid has been investigated numerically at seven different Reynolds numbers;$\mathit{Re}= 50, 75, 100, 150, 200, 250$and$300$. In contrast to all earlier investigations, the major axis of the spheroid was oriented perpendicular to the free stream flow. As expected, the flow field in the wake showed a strong resemblance of that observed behind a finite-length circular cylinder, yet had features observed in the axisymmetric wake behind a sphere. The following different flow regimes were observed in the present computational study: (i) steady laminar flow with massive flow separation and symmetry about the equatorial and the meridional planes at$\mathit{Re}= 50$; (ii) steady laminar flow with massive flow separation and symmetry about the equatorial and the meridional plane at$\mathit{Re}= 75$, but the flow in the equatorial plane did no longer resemble the steady wake behind a circular cylinder; (iii) unsteady laminar flow with Strouhal number$0. 109$and symmetry about the equatorial plane at$\mathit{Re}= 100$; (iv) unsteady laminar flow with two distinct frequencies and without any planar symmetries at$\mathit{Re}= 200$; (v) transitional flow with a dominant shedding frequency$\mathit{St}= 0. 151$and without any spatial symmetries at$\mathit{Re}= 300$. For all but the two lowest$\mathit{Re}$hairpin vortices were alternately shed from the two sides of the spheroid and resulted in a ladder-like pattern of oppositely oriented vortex structures, in contrast with the single-sided shedding in the wake of a sphere. The contour of the very-near-wake mimicked the shape of the prolate spheroid. However,$15d$downstream the major axis of the wake became aligned with the minor axis of the spheroid. This implies that an axis switching occurred some$10d$downstream, i.e. the cross-section of the wake evolved such that the major and minor axes interchanged at a certain downstream location. This peculiar phenomenon has frequently been reported to arise for elliptical and rectangular jets, whereas observations of axis switching for asymmetric wakes are scarce.
Hydrodynamic and thermodiffusive instability effects on the evolution of laminar planar lean premixed hydrogen flames
Authors: Altantzis C. , Frouzakis C. E. , Tomboulides A. G. , Matalon M. , Boulouchos K. 
Published: May 2012

AbstractNumerical simulations with single-step chemistry and detailed transport are used to study premixed hydrogen/air flames in two-dimensional channel-like domains with periodic boundary conditions along the horizontal boundaries as a function of the domain height. Both unity Lewis number, where only hydrodynamic instability appears, and subunity Lewis number, where the flame propagation is strongly affected by the combined effect of hydrodynamic and thermodiffusive instabilities are considered. The simulations aim at studying the initial linear growth of perturbations superimposed on the planar flame front as well as the long-term nonlinear evolution. The dispersion relation between the growth rate and the wavelength of the perturbation characterizing the linear regime is extracted from the simulations and compared with linear stability theory. The dynamics observed during the nonlinear evolution depend strongly on the domain size and on the Lewis number. As predicted by the theory, unity Lewis number flames are found to form a single cusp structure which propagates unchanged with constant speed. The long-term dynamics of the subunity Lewis number flames include steady cell propagation, lateral flame movement, oscillations and regular as well as chaotic cell splitting and merging.
Oscillatory sensitivity patterns for global modes in wakes
Authors: Tammisola Outi 
Published: May 2012

AbstractGlobally unstable wakes with co-flow at intermediate Reynolds numbers are studied, to quantify important spatial regions for the development and control of the global instability. One region of high structural sensitivity is found close to the inlet for all wakes, in agreement with previous findings for cylinder wakes. A second, elongated region of high structural sensitivity is seen downstream of the first one for unconfined wakes at$\mathit{Re}= 400$. When base-flow modifications are considered, a spatially oscillating sensitivity pattern is found inside the downstream high-structural-sensitivity region. This implies that the same change in the base flow can either destabilize or stabilize the flow, depending on the exact position where it is applied. It is shown that the sensitivity pattern remains unchanged for different choices of streamwise boundary conditions and numerical resolution. The actual base-flow is modified in selected configurations, and the linear global modes recomputed. It is confirmed that the linear global eigenvalues move according to the predicted sensitivity pattern for small-amplitude base-flow modifications, for which the theory applies. We also look at the implications of a small control cylinder for the flow. Only the upstream high-sensitivity region proves to be robust in terms of control, but one should be careful not to disturb the flow in the downstream high-sensitivity region, in order to achieve control. The findings can have direct implications for the numerical resolution requirements for wakes at higher Reynolds numbers. Furthermore, they provide one more possible explanation for why confined wakes have a more narrow frequency spectrum than unconfined wakes.
On the anisotropy of a low-Reynolds-number grid turbulence
Authors: Djenidi L. , Tardu S. F. 
Published: May 2012

AbstractThe anisotropy of a low-Reynolds-number grid turbulence is investigated through direct numerical simulations based on the lattice Boltzmann method. The focus is on the anisotropy of the Reynolds-stress (${b}_{ij} $) and Reynolds-stress dissipation-rate (${d}_{ij} $) tensors and the approach taken is that using the invariant analysis introduced by Lumley & Newman (J. Fluid Mech., vol. 82, 1977, pp. 161–178). The grid is made up of thin square floating elements in an aligned configuration.The anisotropy is initially high behind the grid and decays quickly as the downstream distance increases. The anisotropy invariant map (AIM) analysis shows that the return-to-isotropic trend of both ${b}_{ij} $ and ${d}_{ij} $ is fast and follows a perfectly axisymmetic expansion, although just behind the grid there is an initial tendency toward a one-component state. It is found that the linear relation ${d}_{ij} = A{b}_{ij} $ with $A= 0. 21$ is satisfied during the return-to-isotropy phase of the turbulence decay, although close to the grid a form ${d}_{ij} = f({b}_{ij} )$, where $f$ is a nonlinear function of ${b}_{ij} $, is more appropriate. For large downstream distances, ${d}_{ij} $ becomes almost independent of ${b}_{ij} $, suggesting that despite the absence of an inertial range, the (dissipative) small scales present a high degree of isotropy. It is argued that (i) the very small values of the mean strain rate and (ii) the weak anisotropy of the large scales are in fact responsible for this result.
Resonant behaviour of an oscillating wave energy converter in a channel
Authors: Renzi Emiliano , Dias F. 
Published: May 2012

AbstractA mathematical model is developed to study the behaviour of an oscillating wave energy converter in a channel. During recent laboratory tests in a wave tank, peaks in the hydrodynamic actions on the converter occurred at certain frequencies of the incident waves. This resonant mechanism is known to be generated by the transverse sloshing modes of the channel. Here the influence of the channel sloshing modes on the performance of the device is further investigated. Within the framework of a linear inviscid potential-flow theory, application of Green’s theorem yields a hypersingular integral equation for the velocity potential in the fluid domain. The solution is found in terms of a fast-converging series of Chebyshev polynomials of the second kind. The physical behaviour of the system is then analysed, showing sensitivity of the resonant sloshing modes to the geometry of the device, which concurs in increasing the maximum efficiency. Analytical results are validated with available numerical and experimental data.
Between town and country: shifting identity and migrant youth in Uganda
Authors: Barratt Caroline , Mbonye Martin , Seeley Janet 
Published: May 2012

ABSTRACTIn Uganda, as in many other African countries, increasing numbers of 15–24 year olds are migrating to urban areas to look for work and educational opportunities. We explore the shifting sense of identity amongst youth migrants in Uganda as they struggle to reconcile the differences in social norms between the rural settings in which they are brought up and the urban environment in which they now live. The experience of migration significantly impacts on the transition from youths to adults by influencing their perception of their own identity as well as the expectations of society. Young people often hold conflicting views of their rural and urban experiences, suggesting that understanding rural and urban realities as distinct entities does not reflect the complex relationship, and possible confusion, of the migrant experience. In contrast to existing literature on migrant identities, which has tended to focus on the identity shift experienced by adult transnational migrants, this reveals the particular challenges faced by youth migrants whose adult self is not yet formed.
HIV/AIDS policies in Mozambique and the new aid architecture: successes, shortcomings and the way forward
Authors: Bidaurratzaga-Aurre Eduardo , Colom-Jaén Artur 
Published: May 2012

ABSTRACTHIV/AIDS policies have become a significant and controversial issue in Mozambique in recent years. The extent of the disease, along with a massive involvement of the donor community and a committed response by Mozambican authorities, are the main drivers of these policies. In the framework of the new aid architecture, donors are expected to encourage recipient country ‘ownership’ of development policies through new aid instruments like budget support or sector-wide approaches. However, HIV/AIDS policies in Mozambique are highly influenced by donors, because an exceptionally high proportion of the financial resources and policy formation comes from them. In this article we assess the extent of HIV/AIDS and its effects in Mozambique, and analyse the successes and shortcomings of the policies to fight the disease, emphasising the role of donors. We end by exploring possible ways to increase ownership and effectiveness.
Executive dominance and the politics of quota representation in Uganda
Authors: Muriaas Ragnhild L. , Wang Vibeke 
Published: May 2012

ABSTRACTQuota policies securing the presence of marginalised groups in decision-making bodies have been adopted across sub-Saharan Africa. These policies are frequently understood through the lens of a pluralist perspective. This stance is not appropriate in African regimes characterised by executive dominance. Through a qualitative study of official documents, newspaper articles and interviews conducted during two field studies in Uganda in 2005 and 2010, this article shows how the understanding of quota policies in Africa may gain from the corporatist debate on interest representation. The analysis reveals that the incumbent National Resistance Movement has employed the reserved seat policy strategically to maintain its dominant position, and that strategies for using the quota system have evolved gradually over time in response to key political events, and the interests of group activists at the local and national levels with vested interests in its survival.