bluuebunny/crossref_metadata_2025 huggingface dataset:
Activity Landscapes, Information Theory, and Structure – Activity Relationships
Authors: Iyer Preeti , Stumpfe Dagmar , Vogt Martin , Bajorath J. , Maggiora G. M.
Published: February 2013

Activity landscapes provide a comprehensive description of structure‐activity relationships (SARs). An information theoretic assessment of their features, namely, activity cliffs, similarity cliffs, smooth‐SAR, and featureless regions, is presented based on the probability of occurrence of these features. It is shown that activity cliffs provide highly informative SARs compared to smooth‐SAR regions, although the latter are the basis for most QSAR studies. This follows since small structural changes in the former are coupled with relatively large changes in activity, thus pinpointing specific structural features associated with the changes in activity. In contrast, Smooth‐SAR regions are typically associated with relatively small changes in both structure and activity. Surprisingly, similarity cliffs, which occur when both compounds in a compound‐pair have approximately equal activities but significantly different structures, are the most prevalent feature of activity landscapes. Hence, from an information theoretic point of view, they are the least informative landscape feature. Nevertheless, similarity cliffs do provide SAR information on potentially new active compound classes, and in that sense they are quite useful in drug discovery programs since they provide alternative possibilities should ADMET or other issues arise during the discovery and earlier preclinical development phases of drug research.
Removal of blur in images based on least squares solutions
Authors: Stanimirović Predrag S. , Chountasis Spiros , Pappas Dimitrios , Stojanović Igor
Published: February 2013

We propose an image restoration method. The method generalizes image restoration algorithms that are based on the Moore–Penrose solution of certain matrix equations that define the linear motion blur. Our approach is based on the usage of least squares solutions of these matrix equations, wherein an arbitrary matrix of appropriate dimensions is included besides the Moore–Penrose inverse. In addition, the method is a useful tool for improving results obtained by other image restoration methods. Toward that direction, we investigate the case where the arbitrary matrix is replaced by the matrix obtained by the Haar basis reconstructed image. The method has been tested by reconstructing an image after the removal of blur caused by the uniform linear motion and filtering the noise that is corrupted with the image pixels. The quality of the restoration is observable by a human eye. Benefits of using the method are illustrated by the values of the improvement in signal‐to‐noise ratio and in the values of peak signal‐to‐noise ratio. Copyright © 2013 John Wiley & Sons, Ltd.
High‐efficiency inverse class‐E power amplifier with envelope tracking technique
Authors: Kam Sang‐Ho , Kwon Oh‐Seung , Lee Mun‐Woo , Jeong Yoon‐Ha
Published: February 2013

This letter describes a highly efficient inverse class‐E power amplifier (PA) with an envelope tracking (ET) technique.To enhance efficiency performances, the PA uses a harmonic control network with double composite right/left‐handed transmission lines. The use of the ET technique also results in high efficiency for the modulated signals. For verifications, the inverse class‐E PA is implemented with a 35‐W GaN HEMT and tested using 3.5 GHz continuous wave (CW) and 802.16e WiMAX signals. With the CW signal, a peak drain efficiency of 79.0% with a power gain of 9.8 dB is achieved at a saturation output power of 45.6 dBm. With WiMAX signals, a drain efficiency of 37.8% with a power‐added efficiency (PAE) of 33.6% is achieved at an average output power of 36 dBm, which is the 9.6 dB back‐off power region, using the ET technique. After the DPD technique, the linearity significantly improved without decreasing efficiency. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:866–869, 2013; View this article online at wileyonlinelibrary.com. DOI: 10.1002/mop.27420
Ultra‐wideband band‐pass filter with dual narrow notched bands based on dual‐mode stepped impedance resonator
Authors: Wei Feng , Chen Lei , Wang Zhu Dan , Shi Xiao Wei
Published: February 2013

A compact ultra‐wideband (UWB) band‐pass filter (BPF) with dual narrow notch‐bands based on a dual‐mode stepped impedance resonator (SIR) is presented.The proposed UWB filter employed broadside‐coupled microstrip ring‐coplanar waveguide structure. Two notch bands are obtained by introducing one coupled dual‐mode SIR with metalized via hole to ground. Theoretical and simulated results are presented, which are in good agreement with the measured results. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:727–730, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27450
Design of wideband microstrip antenna array at L‐band for synthetic aperture radar applications
Authors: Sharma Devendra Kumar , Pandey Balendu Kumar , Kulshrestha Sanjeev , Chakrabarty S. B. , Jyoti Rajeev
Published: February 2013

This paper presents the design and development of wideband dual‐polarized microstrip array antenna at L‐band for spaceborne synthetic aperture radar (SAR) applications. A new type of electromagnetically coupled microstrip patch fed by strip‐loaded coaxial probe has been used as single antenna element. These radiating elements have been combined to form a 2×6 array antenna using feeder network in stripline configuration. The simulated and measured performance on return loss and radiation parameters has been presented. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:903–908, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27453
Sprayed antenna on cans for WLAN‐RFID tags
Authors: Zuazola I. J. García , Sharma A. , Batchelor J. C. , Angulo I. , Perallos A. , Elmirghani J. M. H.
Published: February 2013

A directly printed antenna onto a can body using copper conductive paint and suited for Radio Frequency Identification Wireless LAN (RFID‐WLAN) tag applications is presented. The antenna unit is low‐cost and compact, provide reasonable gain, and serve prospect RFID transponders with a range of IC impedances. The antenna is fabricated with dimensions of 0.18λ × 0.20λ × 3.61e‐4λ and is relaxed from manufacturing. A design study has been carried out to assess the tuning of the characteristic impedance of the antenna. Return loss, load impedance, and radiation patterns are shown. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:773–775, 2013; View this article online at wileyonlinelibrary.com. DOI: 10.1002/mop.27458
Fe(III) distribution varies substantially within and between atherosclerotic plaques
Authors: Gustafsson H. , Hallbeck M. , Norell M. , Lindgren M. , Engström M. , Rosén A. , Zachrisson H.
Published: February 2013

Purpose

Vulnerable atherosclerotic plaques are structurally weak and prone to rupture, presumably due to local oxidative stress. Redox active iron is linked to oxidative stress and the aim of this study was to investigate the distribution of Fe(III) in carotid plaques and its relation to vulnerability for rupture.

Methods

Atherosclerotic plaques from 10 patients (three asymptomatic and seven symptomatic) were investigated. Plaque vulnerability was classified using ultrasound and immunohistochemistry and correlated to Fe(III) measured by electron paramagnetic resonance spectroscopy.

Results

Large intra‐plaque Fe(III) variations were found. Plaques from symptomatic patients had a higher Fe(III) concentration as compared with asymptomatic plaques (0.36 ± 0.21 vs. 0.06 ± 0.04 nmol Fe(III)/mg tissue, P < 0.05, in sections adjoining narrowest part of the plaques). All but one plaque from symptomatic patients showed signs of cap rupture. No plaque from asymptomatic patients showed signs of cap rupture. There was a significant increase in cap macrophages in plaques from symptomatic patients compared with asymptomatic patients (31 ± 11% vs. 2.3 ± 2.3%, P < 0.01).

Conclusion

Fe(III) distribution varies substantially within atherosclerotic plaques. Plaques from symptomatic patients had significantly higher concentrations of Fe(III), signs of cap rupture and increased cap macrophage activity. Magn Reson Med 71:885–892, 2014. © 2013 Wiley Periodicals, Inc.
A noninvasive tumor oxygenation imaging strategy using magnetic resonance imaging of endogenous blood and tissue water
Authors: Zhang Zhongwei , Hallac Rami R. , Peschke Peter , Mason Ralph P.
Published: February 2013

Purpose

To present a novel imaging strategy for noninvasive measurement of tumor oxygenation using MR imaging of endogenous blood and tissue water.

Theory and Methods

The proposed approach for oxygen partial pressure (pO2) estimation is based on intravoxel incoherent motion diffusion MRI and the dependence of the blood R2 relaxation rate on the inter‐echo spacing measured using a multiple spin‐echo Carr‐Purcell‐Meiboom‐Gill sequence and weak‐field diffusion model. The accuracy of the approach was validated by comparison with 19F MRI oximetry.

Results

The results in eight rats at 4.7 T showed that tumors have longer T1 (1980 ± 186 ms) and T2 (59 ± 9 ms) relaxation times, heterogeneous blood volume fraction (0.23 ± 0.1), oxygen saturation level (Y) (0.53 ± 0.12), and pO2 (36 ± 15 mmHg) distributions compared with normal muscle (T1 1480 ± 86 ms, T2 29 ± 2 ms, blood volume fraction 0.22 ± 0.03, Y 0.49 ± 0.06, and pO2 39 ± 5 mmHg). pO2 estimates based on the novel 1H approach were essentially identical with 19F observations.

Conclusion

The study indicates that noninvasive measurement of tumor pO2 using 1H MRI derived multiparametric maps is feasible and could become a valuable tool to evaluate tumor hypoxia. Magn Reson Med 71:561–569, 2014. © 2013 Wiley Periodicals, Inc.
Fluorinated Boron‐Dipyrromethene (BODIPY) Dyes: Bright and Versatile Probes for Surface Analysis
Authors: Hecht Mandy , Fischer Tobias , Dietrich Paul , Kraus Werner , Descalzo Ana B. , Unger Wolfgang E. S. , Rurack Knut
Published: February 2013

Invited for this month′s cover is the group of Dr. Knut Rurack. The cover picture shows a bright fluorescent dye (green halo) containing a high number of fluorine atoms (blue) for the assessment of reactive amino groups on a glass surface by two complementary surface analytical techniques. For more details, see the Full Paper on p. 25 ff.
Signal intensity changes of the fetal liver on MRI in‐phase and out‐of‐phase sequence
Authors: Li Xiaobing , Brugger Peter C. , Huang Min , Kasprian Gregor , Li Hong , Bettelheim Dieter , Prayer Daniela
Published: February 2013

Objective

To study signal intensity (SI) of the fetal liver by MRI in‐phase and out‐of‐phase over gestational age (GA).

Methods

A total of 91 pregnant women from 19 to 38 gestational weeks were imaged using MRI. Liver‐to‐spleen SI ratios of the right and left fetal liver lobes on in‐phase and out‐of‐phase were measured, calculated, and compared with each other. Curves of liver‐to‐spleen SI ratio of the right and left liver lobe were plotted by GA.

Results

Liver‐to‐spleen SI ratio of the right lobe on in‐phase was different from that of the left liver lobe (t = 3.95; p < 0.001). A statistically significant difference was also found for out‐of‐phase SI ratios (t = 3.69; p < 0.001). Curves of liver‐to‐spleen SI ratio of the fetal liver on in‐phase and out‐of‐phase showed changes against GA.

Conclusion

Liver‐to‐spleen SI ratio is different between the right and left liver lobe, which probably results from the different blood supply. Curves of liver‐to‐spleen SI ratios between 19 to 38 gestational weeks reflect the changes of decreasing function of blood production by fetal liver. In‐phase and out‐of‐phase may have clinical use in the early detection of disordered fetal growth and metabolism. © 2013 John Wiley & Sons, Ltd.
Nano‐Ruby: A Promising Fluorescent Probe for Background‐Free Cellular Imaging
Authors: Edmonds Andrew M. , Sobhan Mushtaq A. , Sreenivasan Varun K. A. , Grebenik Ekaterina A. , Rabeau James R. , Goldys Ewa M. , Zvyagin Andrei V.
Published: February 2013

Bioprobes based on fluorescent ruby nanoparticles, which are suitable for ultrasensitive imaging, are reported. A stable aqueous/buffer colloid, permitting facile conjugation to proteins, is produced by femtosecond laser ablation of ruby and the nanoparticles (mean size 17 nm) are photostable, with long lifetime (1–4 ms) 694 nm emission. With time‐gating complete (>20 dB) suppression of cell autofluorescence and suppression of exogenous fluorophores is observed. Nanoparticles are imaged in as‐grown cells and those immunolabeled with quantum dots. Immunoassay binding to target biomolecules is also demonstrated.
A theoretical study of the effects of transition metal dopants on the adsorption and dissociation of hydrogen on nickel clusters
Authors: Venkataramanan Natarajan Sathiyamoorthy , Suvitha Ambigapathy , Mizuseki Hiroshi , Kawazoe Yoshiyuki
Published: February 2013

The structure, stability, adsorption, and dissociation of H2 on nickel clusters doped with late transition metals were investigated using density functional theory with the BP86 functional. Molecular hydrogen physisorption occurred at a vertex atom with a low coordination number. Charge transfer between clusters and the H2 molecule stabilized the physisorption. The chemisorption of H2 occurred at the bridge sites, without any structural or spin change of the clusters. Among the pentamer clusters, Cd, Zn, and Au had the lowest chemisorption energies, while Ir and Pt had higher chemisorption energies for hydrogen. The computed reaction energies and activation barriers for the dissociation mechanism showed that dopants such as Rh, Pd, Pt, and Au have endothermic reaction energies and low activation barriers. This facilitates the reversible adsorption/dissociation of the H2 molecule on these metal‐doped clusters. The dopant atoms play a major role in modulating the physisorption, chemisorption, and dissociation mechanism of H2 on nickel clusters. © 2013 Wiley Periodicals, Inc.
Quantum chemistry in studies of fluorescent and photosensing proteins
Authors: Nemukhin Alexander , Topol Igor , Collins Jack , Khrenova Maria
Published: February 2013

This Perspective describes some of the recent successes in modeling properties of chromophore containing domains of proteins capable to respond to visible light by using quantum chemistry methods. Applications to two distinctively different classes of such proteins are considered: those of the green fluorescent protein family with the chromophores derived from the hydroxybenzylidene‐imidazolinone moiety and those containing the flavin‐based chromophore. The major emphasis is on applications of economic computational strategies to estimate geometry configurations and electronic excitation energies. We show that using the molecular cluster approach and the “black‐box” methods ZINDO and SOS‐CIS(D) proves to be efficient for characterization of protein spectra. © 2013 Wiley Periodicals, Inc.
Formation of Au/Pd–Sn trimetallic particles onto vitreous carbon
Authors: Meier L. A. , Ferron J. , García S. G. , Salinas D. R.
Published: February 2013

The sequential deposition process of Pd and Sn on Au microcrystals, previously electrodeposited onto vitreous carbon (VC) was investigated in sulphuric acid solution by cyclic voltammetry and Auger electron spectroscopy (AES). Scanning electron microscopy was used to characterize Au deposits. The results reveal that the deposition of Pd and Sn is selective on the Au microcrystals, uniformly distributed on the VC surface, due to the strong interaction energy between the three metals. From the cyclic voltammetric and AES measurements in the VC/Au/Pd/Sn system, the existence of a Sn core–shell structure with Pd can be inferred. Similar voltammetric results were obtained for the VC/Au/Sn/Pd system, where in this case, the Pd adsorbed layer screened the Sn deposits on the VC/Au interface. However, the AES spectrum shows that Sn is still present on the surface, indicating that probably, the Sn deposits have diffused to the surface, or they are not completely covered by Pd. The VC/Au/Pd/Sn modified substrate appears as an interesting electrocatalyst material for the reduction of nitrate ions. Copyright © 2013 John Wiley & Sons, Ltd.
Interpreting meta‐regression: application to recent controversies in antidepressants’ efficacy
Authors: Petkova Eva , Tarpey Thaddeus , Huang Lei , Deng Liping
Published: February 2013

A recent meta‐regression of antidepressant efficacy on baseline depression severity has caused considerable controversy in the popular media. A central source of the controversy is a lack of clarity about the relation of meta‐regression parameters to corresponding parameters in models for subject‐level data. This paper focuses on a linear regression with continuous outcome and predictor, a case that is often considered less problematic. We frame meta‐regression in a general mixture setting that encompasses both finite and infinite mixture models. In many applications of meta‐analysis, the goal is to evaluate the efficacy of a treatment from several studies, and authors use meta‐regression on grouped data to explain variations in the treatment efficacy by study features. When the study feature is a characteristic that has been averaged over subjects, it is difficult not to interpret the meta‐regression results on a subject level, a practice that is still widespread in medical research. Although much of the attention in the literature is on methods of estimating meta‐regression model parameters, our results illustrate that estimation methods cannot protect against erroneous interpretations of meta‐regression on grouped data. We derive relations between meta‐regression parameters and within‐study model parameters and show that the conditions under which slopes from these models are equal cannot be verified on the basis of group‐level information only. The effects of these model violations cannot be known without subject‐level data. We conclude that interpretations of meta‐regression results are highly problematic when the predictor is a subject‐level characteristic that has been averaged over study subjects. Copyright © 2013 John Wiley & Sons, Ltd.
Application of systems engineering to integrate ageing management into maintenance management of oil and gas facilities
Authors: Pérez Ramírez Pedro A. , Bouwer Utne Ingrid , Haskins Cecilia
Published: February 2013

Oil companies and relevant institutions are becoming increasingly aware that effective measures must be put in place to extend the life of installations that are approaching, or have passed, the end of their design lifetime. The implementation of ageing management (AM) facilitates ensuring that the degradation of the installations is properly controlled and mitigated, and their integrity is maintained during the life extension. Integrating AM within an existing process such as maintenance management, which shares various goals and objectives with AM, seems to have several advantages over the alternative of creating a new process for AM. A key issue is to identify and optimize the changes in the maintenance management process for addressing and managing ageing. This paper reports on the use of a systems engineering approach and information models for identifying the “as is” and “to be” processes of existing maintenance management of an oil and gas facility in order to fulfill the new requirements for AM. The primary contribution of this report is to demonstrate the power of these models, combined with a systems engineering process, to reverse engineer legacy practices as the basis for introducing new processes, procedures and training. ©2013 Wiley Periodicals, Inc. Syst Eng 16:
Predictors of neonatal morbidity in fetuses with severe isolated congenital diaphragmatic hernia undergoing fetoscopic tracheal occlusion
Authors: Doné E. , Gratacos E. , Nicolaides K. H. , Allegaert K. , Valencia C. , Castañon M. , Martinez J.‐M. , Jani J. , Van Mieghem T. , Greenough A. , Gomez O. , Lewi P. , Deprest J.
Published: February 2013

Objectives

To investigate neonatal morbidity in fetuses with severe congenital diaphragmatic hernia (CDH) treated with fetoscopic endoluminal tracheal occlusion (FETO) and compare it with historical controls with less severe forms of CDH that were managed expectantly.

Methods

This was a prospective, multicenter study on neonatal outcomes and prenatal predictors in 90 FETO survivors (78 left‐sided, 12 right) and 41 controls from the antenatal CDH registry with either severe or moderate hypoplasia who were managed expectantly. We also investigated early neonatal morbidity indicators, including the need for patch repair, duration of mechanical ventilation and supplemental oxygen, age at full enteral feeding and incidence of pulmonary hypertension.

Results

Gestational age at delivery was predictive of duration of assisted ventilation (P = 0.046), days on supplemental oxygen (P = 0.019) and age at full enteral feeding (P = 0.020). When delivery took place after 34 weeks' gestation, neonatal morbidity of FETO cases was comparable with that of expectantly managed cases with moderate hypoplasia.

Conclusions

Fetal intervention for severe CDH is associated with neonatal morbidity that is comparable with that of an expectantly managed group with less severe disease. Copyright © 2013 ISUOG. Published by John Wiley & Sons Ltd.
High-cell-density culture strategies for polyhydroxyalkanoate production: a review
Authors: Ienczak Jaciane Lutz , Schmidell Willibaldo , de Aragão Gláucia Maria Falcão
Published: February 2013

This article gives an overview of high-cell-density cultures for polyhydroxyalkanoate (PHA) production and their modes of operation for increasing productivity. High cell densities are very important in PHA production mainly because this polymer is an intracellular product accumulated in various microorganisms, so a high cellular content is needed for the polymer production. This review describes relevant results from fed-batch, repeated batch, and continuous modes of operation without and with cell recycle for the production of these polymers by microorganisms. Finally, recombinant microorganisms for PHA production, as well future directions for PHA production, are discussed.
“Bounded” Empowerment: Analyzing Tensions in the Practice of Youth‐Led Participatory Research in Urban Public Schools
Authors: Ozer Emily J. , Newlan Sami , Douglas Laura , Hubbard Elizabeth
Published: February 2013

This multi‐method study examines tensions in the practice of youth‐led participatory research (YPAR) in urban high schools among 15 semester‐cohorts. Student participants in the present study were 77 ethnically diverse youth from four high schools in a major metropolitan school district. Data were gathered using systematic classroom observations, interviews with teachers and students involved in the projects, and participant observation. The two most commonly‐constrained phases of the YPAR project were issue selection and action steps. A central tension in the issue selection phase for projects enacted across multiple semester cohorts was the tension between original inquiry and “traction:” Sticking with the same topic enabled sustained building of strategic alliances and expertise for making change, but limited the incoming cohort's power to define the problem to be addressed. In further analyses, we identified processes that promoted student power despite continuity‐related constraints—teachers’ framing and buy‐in strategies, “micro‐power” compensation, and alignment of students’ interests with the prior cohort—as well as constraints in other phases of the projects. This study's findings regarding the promotion of youth power in the face of constraints advance the integration of theory and practice in youth‐led research and have implications for participatory research more broadly.
Dilatation of the Bile Duct in Patients after Cholecystectomy: A Retrospective Study
Authors: Landry David , Tang An , Murphy-Lavallée Jessica , Lepanto Luigi , Billiard Jean-Sébastien , Olivié Damien , Sylvestre Marie-Pierre
Published: February 2013

Purpose

Retrospective assessment of impact of cholecystectomy, age, and sex on bile duct (BD) diameter.

Materials and Methods

We retrospectively reviewed abdominal contrast-enhanced multidetector computed tomography and laboratory reports of 290 consecutive patients (119 men; mean age, 55.9 years) who presented without cholestasis to the emergency department of our institution between June 2009 and August 2010. BD diameters were measured in 3 locations, by 2 independent observers, twice, at 1-month intervals. Reproducibility and agreement were evaluated by intraclass correlation coefficients and Bland-Altman analyses. The effects of cholecystectomy, age, and sex on BD diameter were analysed with linear mixed models.

Results

BD diameter inter-reader reproducibility and agreement were excellent at the level of the right hepatic artery (intraclass correlation coefficient, 0.94). Sixty-one patients (21.0%) had a history of cholecystectomy. Among them, the 95th percentile of BD diameters at hepatic artery level was 7.9 mm (<50 years) and 12.3 mm (≥50 years). Among those without cholecystectomy, BD diameter was 6.2 mm (<50 years) and 7.7 mm (≥50 years). Cholecystectomy was associated with significantly larger BD diameters in both age groups ( P < .001). Older age was associated with larger BD diameters ( P = .004). Sex had no impact on BD diameter ( P = .842).

Conclusion

Patients after cholecystectomy may present with an enlarged BD unrelated to cholestasis. The BD diameter increases with age. Clinicians should rely on cholecystectomy status, age, and laboratory results to determine needs of further investigation.
Specialization from synthesis: How ribosome diversity can customize protein function
Authors: Filipovska Aleksandra , Rackham Oliver
Published: February 2013

It was thought that the proteins produced by ribosomes were dictated only by the sequences of the mRNAs they translated, however it is becoming apparent that subpopulations of ribosomes can have unique properties that influence the functions of the proteins they produce. Ribosomes have been engineered to discriminate between different mRNA templates or with unique decoding properties, and many new applications of unnatural ribosomes can be foreseen. In natural systems ribosomes with alternate protein and RNA composition have been shown to selectively translate specific mRNAs. As more is learned about ribosome structure and the mechanisms of translation, new opportunities to engineer ribosomes for applications in biotechnology and synthetic biology can be developed and new examples of ribosome‐mediated regulation of translation are likely to emerge in nature.
Course and etiology of dysexecutive MCI in a community sample
Authors: Huey Edward D. , Manly Jennifer J. , Tang Ming‐X. , Schupf Nicole , Brickman Adam M. , Manoochehri Masood , Mez Jesse , DeCarli Charles , Devanand Davangere P. , Mayeux Richard
Published: February 2013

Background

Amnestic mild cognitive impairment (aMCI) is associated with an elevated risk of progressing to Alzheimer's disease. Much less is known about the course of dysexecutive mild cognitive impairment (dMCI). The goals of this study were to determine how the profile of cognitive deficits differs over time between patients with dMCI and aMCI, and control subjects; if the type of dementia differs between dMCI and aMCI in patients who progress to dementia; and if dMCI is more associated with stroke and white matter hyperintensity on magnetic resonance imaging (MRI) than aMCI.

Methods

The authors undertook a prospective evaluation of an inception cohort of 1167 ethnically diverse elders recruited from an urban community‐based sample monitored with clinical and neuropsychological testing for an average of 4.5 years (standard deviation, 0.8 year). A subset of the subjects underwent MRI. We compared four groups of MCI patients: single‐domain amnestic and dysexecutive MCI, and multiple‐domain MCI with and without executive dysfunction.

Results

Compared with aMCI, dMCI was less likely to involve other areas of cognition over time and progress to dementia. None of the 33 single‐domain dMCI patients progressed to dementia. The presence of executive dysfunction in multiple‐domain MCI did not increase risk of progression to dementia. Patients with multiple‐domain MCI with executive dysfunction who progressed to dementia were less likely to have an Alzheimer's–type dementia than MCI patients without executive dysfunction. Patients with dMCI were more likely to experience stroke, but not white matter hyperintensity, detected via MRI than patients with aMCI.

Conclusions

dMCI appears to follow a different course, and is less associated with Alzheimer's disease and more associated with stroke than aMCI.
Phase-averaged equation for water waves
Authors: Gramstad Odin , Stiassnie Michael
Published: February 2013

We investigate phase-averaged equations describing the spectral evolution of dispersive water waves subject to weakly nonlinear quartet interactions. In contrast to Hasselmann’s kinetic equation, we include the effects of near-resonant quartet interaction, leading to spectral evolution on the ‘fast’ $O({\epsilon }^{- 2} )$ time scale, where $\epsilon $ is the wave steepness. Such a phase-averaged equation was proposed by Annenkov & Shrira (J. Fluid Mech., vol. 561, 2006b, pp. 181–207). In this paper we rederive their equation taking some additional higher-order effects related to the Stokes correction of the frequencies into account. We also derive invariants of motion for the phase-averaged equation. A numerical solver for the phase-averaged equation is developed and successfully tested with respect to convergence and conservation of invariants. Numerical simulations of one- and two-dimensional spectral evolution are performed. It is shown that the phase-averaged equation describes the ‘fast’ evolution of a spectrum on the $O({\epsilon }^{- 2} )$ time scale well, in good agreement with Monte-Carlo simulations using the Zakharov equation and in qualitative agreement with known features of one- and two-dimensional spectral evolution. We suggest that the phase-averaged equation may be a suitable replacement for the kinetic equation during the initial part of the evolution of a wave field, and in situations where ‘fast’ field evolution takes place.
Nonlinear long waves over a muddy beach
Authors: Garnier Erell-Isis , Huang Zhenhua , Mei Chiang C.
Published: February 2013

We analyse theoretically the interaction between water waves and a thin layer of fluid mud on a sloping seabed. Under the assumption of long waves in shallow water, weakly nonlinear and dispersive effects in water are considered. The fluid mud is modelled as a thin layer of viscoelastic continuum. Using the constitutive coefficients of mud samples from two field sites, we examine the interaction of nonlinear waves and the mud motion. The effects of attenuation on harmonic evolution of surface waves are compared for two types of mud with distinct rheological properties. In general mud dissipation is found to damp out surface waves before they reach the shore, as is known in past observations. Similar to the Eulerian current in an oscillatory boundary layer in a Newtonian fluid, a mean displacement in mud is predicted which may lead to local rise of the sea bottom.
Direct numerical simulations of local and global torque in Taylor–Couette flow up to Re = 30 000
Authors: Brauckmann Hannes J. , Eckhardt Bruno
Published: February 2013

The torque in turbulent Taylor–Couette flows for shear Reynolds numbers $R{e}_{S} $ up to $3\times 1{0}^{4} $ at various mean rotations is studied by means of direct numerical simulations for a radius ratio of $\eta = 0. 71$. Convergence of simulations is tested using three criteria of which the agreement of dissipation values estimated from the torque and from the volume dissipation rate turns out to be most demanding. We evaluate the influence of Taylor vortex heights on the torque for a stationary outer cylinder and select a value of the aspect ratio of $\Gamma = 2$, close to the torque maximum. The local transport resulting in the torque is investigated via the transverse current ${J}^{\omega } $ which measures the transport of angular momentum and can be computed from the velocity field. The typical spatial distribution of the individual convective and viscous contributions to the local torque is analysed for a turbulent flow case. To characterize the turbulent statistics of the transport, probability density functions (p.d.f.s) of local current fluctuations are compared with experimental wall shear stress measurements. P.d.f.s of instantaneous torques reveal a fluctuation enhancement in the outer region for strong counter-rotation. Moreover, we find for simulations realizing the same shear $R{e}_{S} \geq 2\times 1{0}^{4} $ the formation of a torque maximum for moderate counter-rotation with angular velocities ${\omega }_{o} \approx - 0. 4\hspace{0.167em} {\omega }_{i} $. In contrast, for $R{e}_{S} \leq 4\times 1{0}^{3} $ the torque features a maximum for a stationary outer cylinder. In addition, the effective torque scaling exponent is shown to also depend on the mean rotation state. Finally, we evaluate a close connection between boundary-layer thicknesses and the torque.
Longwave Marangoni convection in a surfactant solution between poorly conducting boundaries
Authors: Shklyaev Sergey , Nepomnyashchy Alexander A.
Published: February 2013

We consider Marangoni convection in a heated layer of a binary liquid. The solute is a surfactant, which is present in both surface and bulk phases; the bulk gradient of the concentration is formed due to the Soret effect. Linear stability analysis demonstrates a well-pronounced stabilization of the layer due to the adsorption kinetics and advection of the surface phase. We derive nonlinear amplitude equations for longwave perturbations in the case of fast sorption kinetics (small Langmuir number) and demonstrate that with increase in the effect of the adsorption, subcritical excitation occurs. In the case of a finite Langmuir number, the weakly nonlinear problem is ill-posed. A physical mechanism of subcritical bifurcation is discussed.
The competition between gravity and flow focusing in two-layered porous media
Authors: Huppert Herbert E. , Neufeld Jerome A. , Strandkvist Charlotte
Published: February 2013

The gravitationally driven flow of a dense fluid within a two-layered porous media is examined experimentally and theoretically. We find that in systems with two horizontal layers of differing permeability a competition between gravity driven flow and flow focusing along high-permeability routes can lead to two distinct flow regimes. When the lower layer is more permeable than the upper layer, gravity acts along high-permeability pathways and the flow is enhanced in the lower layer. Alternatively, when the upper layer is more permeable than the lower layer, we find that for a sufficiently small input flux the flow is confined to the lower layer. However, above a critical flux fluid preferentially spreads horizontally within the upper layer before ultimately draining back down into the lower layer. This later regime, in which the fluid overrides the low-permeability lower layer, is important because it enhances the mixing of the two fluids. We show that the critical flux which separates these two regimes can be characterized by a simple power law. Finally, we briefly discuss the relevance of this work to the geological sequestration of carbon dioxide and other industrial and natural flows in porous media.
Combating the “New Slavery” in Nigeria: An Appraisal of Legal and Policy Responses to Human Trafficking
Authors: Okogbule Nlerum S
Published: February 2013

This article examines the legal and policy responses of the Nigerian government and other agencies to human trafficking, which is one of the central social and economic challenges facing the country today. After exploring the nature and dimensions of the practice, it argues that Nigeria's unenviable position as a country of origin, transit and destination in human trafficking, as well as the impact of the practice on the lives of the victims and adverse implications for the country's corporate image, make it imperative that effective measures are adopted to combat it. In this respect, while accepting that legal measures are important in achieving the objective, the article highlights some deficiencies in current efforts and suggests a multidimensional approach, with greater emphasis on the “push” and “pull” factors of human trafficking prevalent in the country, such as high levels of unemployment, poverty, inequality and marginalization.
Petrous apex cholesterol granuloma: pictorial review of radiological considerations in diagnosis and surgical histopathology
Authors: Hoa M , House J W , Linthicum F H , Go J L
Published: February 2013

Background:

Petrous apex cholesterol granulomas are expansile, cystic lesions containing cholesterol crystals surrounded by foreign body giant cells, fibrous tissue reaction and chronic inflammation. Appropriate treatment relies on an accurate radiological diagnosis and an understanding of the distinguishing radiological features of relevant entities in the differential diagnosis of this condition.

Methods:

Firstly, this paper presents a pictorial review of the relevant radiological features of petrous apex cholesterol granuloma, and highlights unique features relevant to the differential diagnosis. Secondly, it reviews the histopathological and radiological findings associated with surgical drainage of these lesions.

Results:

Radiological features relevant to the differential diagnosis of petrous apex cholesterol granuloma are reviewed, together with radiological and histopathological features relevant to surgical management. Following surgical management, histopathological and radiological evidence demonstrates that the patency of the surgical drainage pathway is maintained.

Conclusion:

Accurate diagnosis of petrous apex cholesterol granuloma is essential in order to instigate appropriate treatment. Placement of a stent in the drainage pathway may help to maintain patency and decrease the likelihood of symptomatic recurrence.
Settlement and recruitment of the barnacleBalanus amphitritefrom a tropical environment influenced by monsoons
Authors: Gaonkar Chetan A. , Anil Arga Chandrashekar
Published: February 2013

Studies on the settlement and the subsequent recruitment of intertidal organisms are crucial steps in understanding their population structure in a particular bioregion. However, studying the recruitment of intertidal organisms such as barnacles, with two-phase life cycle, and understanding the determinants of recruitment is a complex problem. Many processes which operate during the pelagic pre-settlement phase and benthic post-settlement phase at different spatial and temporal scales can determine the fate of barnacle populations. In this study, observations were carried out on settlement and recruitment of the intertidal barnacleBalanus amphitritefrom a tropical environment influenced by monsoons at spatial and temporal scales. Settlement and recruitment both showed significant temporal variations. In general, settlement and recruitment was lower during the monsoon season except during monsoon breaks. Consistency in settlement and recruitment was mostly observed during the pre-monsoon season, and it coincided with peaks in larval abundance observed during the same season. In general, settlement remained more or less similar on different types of substrata, whereas recruitment differed significantly. Temporal variations observed in settlement and recruitment of barnacles could be due to the influence of monsoons in this region, which leads to seasonal fluctuations in physical factors such as local hydrodynamics, that influence the retention and dispersal of larvae in the adult habitats, and could also be due to variations in the availability of food for the larvae and the settled populations.
Fishing down the food web of the Antarctic continental shelf and slope
Authors: Ainley David G. , Pauly Daniel
Published: February 2013

The history of biotic exploitation for the continental margin (shelf and slope) of the Antarctic Large Marine Ecosystem (LME) is reviewed, with emphasis on the period from 1970 to 2010. In the Antarctic Peninsula portion, marine mammals were decimated by the 1970s and groundfish by the early 1980s. Fishing for Antarctic krill Euphausia superba began upon the demise of groundfish and now is the only fishing that remains in this region. Surveys show that cetacean and most groundfish stocks remain severely depressed, harvest of which is now prohibited by the International Whaling Commission and the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). On the other hand, krill fishing in this region is underway and in recent years has contributed up to 72% of the Southern Ocean catch, depending on fishing conditions and the CCAMLR conservation measures in force. Elsewhere along the Antarctic continental margin, marine mammals were also severely depleted by the 1970s, followed directly by relatively low-level fisheries for krill that continued until the early 1990s. Recently in these areas, where fin-fishing is still allowed, fisheries for Antarctic toothfish Dissostichus mawsoni have been initiated, with one of this fish's main prey, grenadiers Macrourus spp., being taken significantly as by-catch. Continental margin fishing currently accounts for ~25% of the total toothfish catch of the Southern Ocean. Fishing along the Antarctic continental margin, especially the Antarctic Peninsula region, is a clear case of both the tragedy of the commons and ‘fishing down the food web’.
The influence of mistletoes on nitrogen cycling in a semi-arid savanna, south-west Zimbabwe
Authors: Ndagurwa Hilton G. T. , Dube John S. , Mlambo Donald
Published: February 2013

This study investigated the effects of mistletoe infection on N cycling in a semi–arid savanna, south-west Zimbabwe. We established five plots (10 × 10 m) which each included three large canopy-dominantAcacia karrootrees infected by one of three mistletoes (Erianthemum ngamicum,Plicosepalus kalachariensisandViscum verrucosum) and non-infectedA. karrootrees. In each plot, we measured litterfall, litter quality (N, phenolics, tannins and lignin), soil nutrient concentrations and N transformations beneath tree canopies. Soil N, P and Ca were greatest beneath trees infected byP.kalachariensisthan beneath non-infected trees. Litterfall and litter N returns were 1.5, 2 and 1.4 times more beneathA. karrootrees infected byE.ngamicum,P.kalachariensisandV. verrucosum, respectively. Mineral N increased with mistletoe infection but did not exceed 20%. Soil N transformations were greater beneath trees infected byE.ngamicum(> 40%), and lower beneath trees infected byP.kalachariensis(<50%) andV.verrucosum(<48%) than beneath non-infectedA. karrootrees. Soil N transformations were negatively correlated with condensed tannins, lignin and lignin : N. We conclude that the improved N concentration can increase resource heterogeneity, which may alter the ecosystem structure and functioning in the semi-arid savanna.
Relative Fourier–Mukai transforms for Weierstraß fibrations, abelian schemes and Fano fibrations
Authors: MARTÍN ANA CRISTINA LÓPEZ , GÓMEZ DARÍO SÁNCHEZ , PRIETO CARLOS TEJERO
Published: February 2013

We study the group of relative Fourier–Mukai transforms for Weierstraß fibrations, abelian schemes and Fano or anti-Fano fibrations. For Weierstraß and Fano or anti-Fano fibrations we describe this group completely. For abelian schemes over an arbitrary base we prove that if two of them are relative Fourier–Mukai partners then there is an isometric isomorphism between the fibre products of each of them and its dual abelian scheme. If the base is normal and the slope map is surjective we show that these two conditions are equivalent. Moreover in this situation we completely determine the group of relative Fourier–Mukai transforms and we prove that the number of relative Fourier–Mukai partners of a given abelian scheme over a normal base is finite.
On the Northcott property and other properties related to polynomial mappings
Authors: CHECCOLI SARA , WIDMER MARTIN
Published: February 2013

We prove that if K/ℚ is a Galois extension of finite exponent and K(d) is the compositum of all extensions of K of degree at most d, then K(d) has the Bogomolov property and the maximal abelian subextension of K(d)/ℚ has the Northcott property.

Moreover, we prove that given any sequence of finite solvable groups {Gm}m there exists a sequence of Galois extensions {Km}m with Gal(Km/ℚ)=Gm such that the compositum of the fields Km has the Northcott property. In particular we provide examples of fields with the Northcott property with uniformly bounded local degrees but not contained in ℚ(d).

We also discuss some problems related to properties introduced by Liardet and Narkiewicz to study polynomial mappings. Using results on the Northcott property and a result by Dvornicich and Zannier we easily deduce answers to some open problems proposed by Narkiewicz.
Tracking sickness through social networks – the practical use of social network mapping in supporting the management of an E. coli O157 outbreak in a primary school in London
Authors: DEVAKUMAR D. , KITCHING A. , ZENNER D. , TOSTMANN A. , MELTZER M.
Published: February 2013

This paper describes the practical use of social network diagrams in the management of an outbreak of Escherichia coli O157 (VTEC) in a primary school in London. The diagrams were created during the outbreak to establish the extent and nature of person-to-person transmission in the cases and their contacts. The diagrams supported a tailored public health action, and hence aided in the control of the outbreak. We conclude that for selected infectious diseases, social network diagrams can provide a valuable tool in the management of an outbreak.
Replacement of glutamine with the dipeptide derivative alanyl-glutamine enhances in vitro maturation of porcine oocytes and development of embryos
Authors: Kim Su Jin , Koo Ok Jae , Kwon Dae Kee , Kang Jung Taek , Park Sol Ji , Gomez Ma Ninia , Atikuzzaman Mohammad , Jang Goo , Lee Byeong-Chun
Published: February 2013

The presence of glutamine (Gln) in in vitro maturation (IVM) and in vitro culture (IVC) medium is a more potent factor for improving porcine oocyte and embryo development than other amino acids. However Gln is inherently unstable and spontaneously breaks down into ammonia, and therefore interferes with proper development. To avoid this adverse effect, Gln was replaced in the present study with its stable dipeptide derivative alanyl-glutamine (Ala-Gln) and the effects of this replacement on porcine IVM and IVC were evaluated. Replacement of Gln with Ala-Gln during IVM did not improve nuclear maturation, however numbers of early cleaved embryos were significantly increased after activation. Blastocyst formation rates were also significantly improved by using Ala-Gln during IVM. Replacement of Gln with Ala-Gln during IVC significantly increased total cell numbers in blastocysts. Blastocyst formation rate was also significantly higher when Ala-Gln was used in both IVM and IVC. In conclusion, the use of Ala-Gln rather than Gln gives better results for development in both porcine IVM and IVC.