bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetic and structural properties of Ba(Co1−xMnx)O3 using synchrotron x-ray spectroscopy
Authors: Shinoda Ryoichi , Iwase Akihiro , Matsui Toshiyuki
Published: December 2014

We report on the relationship between structural and magnetic properties, as well as their Mn-substitution dependence for ceramics Ba(Co1−xMnx)O3 (x = 0.00–0.30) following an analysis using synchrotron X-ray spectroscopy. The crystal structure of samples of Ba(Co1−xMnx)O3 ceramics changed from 2H- to 10H- through 12H-type phases depending on composition ratio x. The saturation magnetization increased in the presence of the 12H-type phase, and decreased in the presence of the 10H-type phase; a maximum value of 2.49 μB/f.u. at 5 K is obtained with composition ratio x = 0.1. The correlation between structural and magnetic properties as well as their dependence on Mn substitution are explained by the preferential occupation of the cubic stacking sites by Mn ions. The 12H-type phase exhibited ferri-magnetic ordering attributed to the ferromagnetic super-exchange coupling of Co4+(d5)–O2−–Mn4+(d3) with a bonding angle of 180°; the 2H- and 10H-type phases exhibited anti-ferromagnetic ordering attributed to the anti-ferromagnetic super-exchange couplings of Co4+(d5) –O2−–Co4+(d5) and Co4+(d5) –O2−–Mn4+(d3), respectively, with a bonding angle of 90°. The saturation magnetization therefore increases with the presence of the ferromagnetic 12H-type phase, whereas it decreases in the presence of the anti-ferromagnetic 10H-type phase.
Magnetic and magnetocaloric properties of Ba and Ti co-doped SrRuO3
Authors: Sarkar Babusona , Dalal Biswajit , Dev Ashok Vishal , De S. K.
Published: December 2014

Temperature evolution of magnetic properties in Ba and Ti doped SrRuO3 has been investigated to observe the effects of larger ionic radius Ba at Sr site and isovalent nonmagnetic impurity Ti at Ru site. Ionic radius mismatch and different electronic configuration in comparison with Ru modify Sr(Ba)-O and Ru(Ti)-O bond lengths and Ru-O-Ru bond angle. The apical and basal Ru-O-Ru bond angles vary significantly with Ti doping. Ferromagnetic Curie temperature decreases from 161 K to 149 K monotonically with Ba (10%) and Ti (10%) substitutions at Sr and Ru sites. The zero field cooled (ZFC) magnetization reveals a prominent peak which shifts towards lower temperature with application of magnetic field. The substitution of tetravalent Ti with localized 3d0 orbitals for Ru with more delocalized 4d4 orbitals leads to a broad peak in ZFC magnetization. A spontaneous ZFC magnetization becomes negative below 160 K for all the compositions. The occurrence of both normal and inverse magnetocaloric effects in Ba and Ti co-doped SrRuO3 makes the system more interesting.
Effect of oxygen annealing on the multiferroic properties of Ca2+ doped BiFeO3 nanoceramics
Authors: Tirupathi Patri , Mandal Satish Kumar , Chandra Amreesh
Published: December 2014

The high leakage current in divalent ion doped BiFeO3 systems is limiting their large scale application. It is clearly shown that the methodology of oxygen annealing will prove to be an effective procedure for suppressing the detrimental consequences that originate from the oxygen vacancies. The samples annealed under oxygen also show different particle morphologies and packing density that can help in tuning the relevant physical properties, viz., magnetic, ferroelectric, and magnetoelectric. The difference in magnetic behaviour in samples annealed in air and oxygen can be explained in terms of the modification in the Fe-O-Fe bonds, domain wall pinning centres, and crystal anisotropy. Another important observation is the stabilization of a dielectric anomaly near the magnetic transition temperature. This observation can make this multiferroic system very interesting for application in sensors where the change in the magnetic parameters can be observed by monitoring the electrical parameters. Detailed analysis of the dielectric and impedance curves indicate towards the presence of non-Debye type processes in samples obtained by annealing in air or oxygen. From the calculated activation energy values, the vacancy related relaxation mechanism is predominant in air annealed samples, while the oxygen annealed samples show the presence of two type of relaxation processes, viz., electron hopping mechanism stabilizes at low temperature while, at higher temperatures, the process associated with the diffusion of doubly ionized oxygen ions predominates. The ac-conductivity data suggests that the correlated barrier tunnelling mechanism, where single electron or two electrons hopping through neighbouring lattice sites leads to ac-conduction.
Effect of geometry and composition on the intraband transitions of holes in quantum dots
Authors: Singh Satish Kumar , Kumar Jitendra
Published: December 2014

The effect of shape and size anisotropy on unipolar intraband transitions of holes in quantum dots (QDs) is studied. The optical matrix elements are calculated for transitions of holes in valence band. To get the optical matrix elements, energy eigenvalues and eigenvectors are calculated using 4 × 4 Luttinger Hamiltonian in the effective mass approximation. The formulation is applied to InGaAs/GaAs QD with parabolic confinement potential in xy-plane. The optical matrix elements for intraband hole transitions are calculated for x and y polarised light. The transitions are considered from ground state to other excited states. The effect of In concentration on optical matrix elements is also investigated. It is important to note that the transitions of holes are governed by the character of initial and final states for different light polarisations that give specific transition selection rules. It is found that the polarisation is strongly dependent on the in-plane anisotropy of the QDs.
A direct numerical simulation-based investigation and modeling of pressure Hessian effects on compressible velocity gradient dynamics
Authors: Danish Mohammad , Suman Sawan , Srinivasan Balaji
Published: December 2014

The pressure Hessian tensor plays a key role in shaping the behavior of the velocity gradient tensor, and in turn, that of many incumbent non-linear processes in a turbulent flow field. In compressible flows, the role of pressure Hessian is even more important because it represents the level of fluid-thermodynamic coupling existing in the flow field. In this work, we first perform a direct numerical simulation-based study to clearly identify, isolate, and understand various important inviscid mechanisms that govern the evolution of the pressure Hessian tensor in compressible turbulence. The ensuing understanding is then employed to introduce major improvements to the existing Lagrangian model of the pressure Hessian tensor (the enhanced Homogenized Euler equation or EHEE) in terms of (i) non-symmetric, non-isentropic effects and (ii) improved representation of the anisotropic portion of the pressure Hessian tensor. Finally, we evaluate the new model extensively by comparing the new model results against known turbulence behavior over a range of Reynolds and Mach numbers. Indeed, the new model shows much improved performance as compared to the EHEE model.
Magnetoimpedance effect at the high frequency range for the thin film geometry: Numerical calculation and experiment
Authors: Corrêa M. A. , Bohn F. , da Silva R. B. , Sommer R. L.
Published: December 2014

The magnetoimpedance effect is a versatile tool to investigate ferromagnetic materials, revealing aspects on the fundamental physics associated to magnetization dynamics, broadband magnetic properties, important issues for current and emerging technological applications for magnetic sensors, as well as insights on ferromagnetic resonance effect at saturated and even unsaturated samples. Here, we perform a theoretical and experimental investigation of the magnetoimpedance effect for the thin film geometry at the high frequency range. We calculate the longitudinal magnetoimpedance for single layered, multilayered, or exchange biased systems from an approach that considers a magnetic permeability model for planar geometry and the appropriate magnetic free energy density for each structure. From numerical calculations and experimental results found in literature, we analyze the magnetoimpedance behavior and discuss the main features and advantages of each structure. To test the robustness of the approach, we directly compare theoretical results with experimental magnetoimpedance measurements obtained at the range of high frequencies for an exchange biased multilayered film. Thus, we provide experimental evidence to confirm the validity of the theoretical approach employed to describe the magnetoimpedance in ferromagnetic films, revealed by the good agreement between numerical calculations and experimental results.
Cu codoping control over magnetic precipitate formation in ZnCoO nanowires
Authors: Granville S. , Matei E. , Enculescu I. , Toimil-Molares Maria Eugenia
Published: December 2014

Using electrodeposition, we have grown nanowires of ZnCoO with Cu codoping concentrations varying from 4–10 at. %, controlled only by the deposition potential. We demonstrate control over magnetic Co oxide nano-precipitate formation in the nanowires via the Cu concentration. The different magnetic behavior of the Co oxide nano-precipitates indicates the potential of ZnCoO for magnetic sensor applications.
Modulation-mediated unlocking of a parametrically phase-locked spin torque oscillator
Authors: Dürrenfeld P. , Iacocca E. , Åkerman J. , Muduli P. K.
Published: December 2014

Modulation of an oscillator is crucial for its application in communication devices. While the output power and linewidth of single magnetic tunnel junction-based spin-torque oscillators (MTJ-STO) are not yet adequate for practical uses, the synchronization of such devices can overcome these limitations. Here, we investigate the modulation behavior of a parametrically synchronized MTJ-STO and show experimentally that modulation of the synchronized state preserves synchronization as long as the modulation frequency, fmod, is above a characteristic frequency, funlock. The unlocking frequency increases with the modulation amplitude in agreement with analytical estimates and numerical simulations. These phenomena are described as a non-resonant unlocking mechanism, whose characteristics are directly related to inherent parameters of the oscillator.
Microsized structures assisted nanostructure formation on ZnSe wafer by femtosecond laser irradiation
Authors: Wang Shutong , Feng Guoying , Zhou Shouhuan
Published: December 2014

Micro/nano patterning of ZnSe wafer is demonstrated by femtosecond laser irradiation through a diffracting pinhole. The irradiation results obtained at fluences above the ablation threshold are characterized by scanning electron microscopy. The microsized structure with low spatial frequency has a good agreement with Fresnel diffraction theory. Laser induced periodic surface structures and laser-induced periodic curvelet surface structures with high spatial frequency have been found on the surfaces of microsized structures, such as spikes and valleys. We interpret its formation in terms of the interference between the reflected laser field on the surface of the valley and the incident laser pulse.
Ferroelectric Bloch-line switching: A paradigm for memory devices?
Authors: Salje E. K. H. , Scott J. F.
Published: December 2014

Vortices inside polar domain walls in ferroelastic materials can form ordered arrays resembling Bloch-lines in magnets. The Bloch lines are energetically degenerate with dipoles oriented perpendicular to the wall. By symmetry, these dipoles are oriented at +90° or −90° relative to the wall dipoles. These two states have the same energy and can be inverted by modest applied electric fields. As the majority of wall dipoles are oriented inside the wall, perpendicular to the Bloch line vortex, weak depolarization fields exist for the wall dipoles but not for Bloch lines. The Bloch line density depends on the density of the twin walls and the elastic anisotropy of the crystal structure. We estimate that distances between twin boundaries are as small as 50 nm and Bloch lines can form with some densities of 100 Bloch lines in an area of 100 × 100 nm2. The local dipole moment in the Bloch line is equivalent to the displacement of Ti in BaTiO3. Switchable Bloch lines can be detected by their macroscopic dipole moment and can constitute the functional part of a memory device.
Time-domain analysis of spin-torque induced switching paths in nanoscale CoFeB/MgO/CoFeB magnetic tunnel junction devices
Authors: Heindl R. , Rippard W. H. , Russek S. E. , Pufall M. R.
Published: December 2014

We performed thousands of single-shot, real-time measurements of spin-transfer-torque induced switching in nanoscale CoFeB/MgO/CoFeB magnetic tunnel junctions having in-plane magnetizations. Our investigation discovered a variety of switching paths occurring in consecutive, nominally identical switching trials of a single device. By mapping the voltage as a function of time to an effective magnetization angle, we determined that reversal of a single device occurs via a variety of thermally activated paths. Our results show a complex switching behavior that has not been captured by previous observations and cannot be fully explained within the simple macrospin model.
Coherent random lasing from liquid waveguide gain channels with biological scatters
Authors: Zhang Hong , Feng Guoying , Wang Shutong , Yang Chao , Yin Jiajia , Zhou Shouhuan
Published: December 2014

A unidirectional coherent random laser based on liquid waveguide gain channels with biological scatters is demonstrated. The optical feedback of the random laser is provided by both light scattering and waveguide confinement. This waveguide-scattering-feedback scheme not only reduces the pump threshold but also makes the output of random laser directional. The threshold of our random laser is about 11 μJ. The emission spectra can be sensitively tuned by changing pump position due to the micro/nano-scale randomness of butterfly wings. It shows the potential applications of optofluidic random lasers for bio-chemical sensors on-chip.
Graphene/mica based ammonia gas sensors
Authors: Ben Aziza Zeineb , Zhang Qing , Baillargeat Dominique
Published: December 2014

In this paper, graphene/mica and graphene/SiO2 based ammonia gas sensors are compared. It is found that adsorbed NH3 molecules result in up-shifting of the Fermi level in graphene, leading to a significant increase in graphene resistance. In comparison with SiO2 supporting substrate, the mica supporting substrate is found to induce more p-doping in graphene, in favour of NH3 molecule adsorption, yielding a high sensitivity. These findings suggest that the substrate plays an important role in mediating the interaction between graphene and NH3 molecules and that mica can be an excellent underlying substrate for graphene for ammonia gas detection.
Role of magnetic fluctuations in mode selection of magnetically driven instabilities
Authors: Dan Jia-Kun , Ren Xiao-Dong , Huang Xian-Bin , Ouyang Kai , Chen Guang-Hua
Published: December 2014

The influences of magnetic fluctuations on quasiperiodic structure formation and fundamental wavelength selection of the instability have been studied using two 25-μm-diameter tungsten wires on a 100  ns rise time, 220 kA pulsed power facility. Two different load configurations were adopted to make end surfaces of electrodes approximately satisfy reflecting and absorbing boundary conditions, respectively. The experimental results that the fundamental wavelength in the case of absorbing boundary condition is about one half of that in the case of reflecting boundary condition have demonstrated that magnetic fluctuations appear to play a key role in mode selection of magnetically driven instabilities. The dominant wavelength should be proportional to magnetic field and inversely proportional to square root of mass density, provided that the magnetosonic wave propagating perpendicular to magnetic fields provides a leading candidate for magnetic fluctuations. Therefore, magnetic fluctuation is one of the three key perturbations, along with surface contaminants and surface roughness, that seeds magnetically driven instabilities.
Generation of full polarization in ferromagnetic graphene with spin energy gap
Authors: Wu Qing-Ping , Liu Zheng-Fang , Chen Ai-Xi , Xiao Xian-Bo , Liu Zhi-Min
Published: December 2014

We propose a workable scheme for the generation of full spin polarization in ferromagnetic graphene system with strain or Rashba spin-orbit interaction. A spin energy gap can be opened in ferromagnetic graphene system in the presence of strain or Rashba spin-orbit interaction, leading to the full polarization in the spin energy gap. In addition, under the combined modulation of strain and Rashba spin-orbit interaction, the ferromagnetic graphene system can generate significantly large spin-polarized current with a full polarization in the spin energy gap. It is anticipated to apply such a phenomenon to design the electron spin devices based on the graphene.
Differential roles of delay-period neural activity in the monkey dorsolateral prefrontal cortex in visual–haptic crossmodal working memory
Authors: Wang Liping , Li Xianchun , Hsiao Steven S. , Lenz Fred A. , Bodner Mark , Zhou Yong-Di , Fuster Joaquín M.
Published: December 2014

Significance

Neural activity was recorded from the dorsolateral prefrontal cortex (DLPFC) when a monkey performed visuo–haptic crossmodal and haptic–haptic unimodal delayed matching-to-sample (cue) tasks. Results indicate that neural networks in the DLPFC function sequentially in the crossmodal task from visual stimulus encoding and crossmodal information transferring between visual and tactile stimuli to the behavioral action. Our findings may clarify the neural mechanisms by which the cerebral cortex stores information in working memory, a cognitive function of prime importance in the coordination of behavior, speech, and reasoning.
Epstein–Barr virus nuclear antigen 3A partially coincides with EBNA3C genome-wide and is tethered to DNA through BATF complexes
Authors: Schmidt Stefanie C. S. , Jiang Sizun , Zhou Hufeng , Willox Bradford , Holthaus Amy M. , Kharchenko Peter V. , Johannsen Eric C. , Kieff Elliott , Zhao Bo
Published: December 2014

Significance

Epstein–Barr Virus (EBV)-infected lymphoblasts can give rise to non-Hodgkin’s lymphomas, Hodgkin’s disease, and lymphoproliferative disorders, especially in immunosuppressed and HIV-infected individuals. EBV-driven lymphoblast growth requires EBV nuclear antigen 3A (EBNA3A) for suppression of CDKN2A-mediated cell senescence responses. We have described the EBNA3A genome-wide landscape in EBV-infected human lymphoblasts. EBNA3A was found mostly at strong enhancers, colocalized with BATF, ETS, IRF4, and RUNX3. EBNA3A was tethered to DNA through BATF protein complexes.
Nup2 requires a highly divergent partner, NupA, to fulfill functions at nuclear pore complexes and the mitotic chromatin region
Authors: Markossian Sarine , Suresh Subbulakshmi , Osmani Aysha H. , Osmani Stephen A.
Published: December 2014

Chromatin and nuclear pore complexes (NPCs) undergo dramatic changes during mitosis, which in vertebrates and Aspergillus nidulans involves movement of Nup2 from NPCs to the chromatin region to fulfill unknown functions. This transition is shown to require the Cdk1 mitotic kinase and be promoted prematurely by ectopic expression of the NIMA kinase. Nup2 localizes with a copurifying partner termed NupA, a highly divergent yet essential NPC protein. NupA and Nup2 locate throughout the chromatin region during prophase but during anaphase move to surround segregating DNA. NupA function is shown to involve targeting Nup2 to its interphase and mitotic locations. Deletion of either Nup2 or NupA causes identical mitotic defects that initiate a spindle assembly checkpoint (SAC)–dependent mitotic delay and also cause defects in karyokinesis. These mitotic problems are not caused by overall defects in mitotic NPC disassembly–reassembly or general nuclear import. However, without Nup2 or NupA, although the SAC protein Mad1 locates to its mitotic locations, it fails to locate to NPCs normally in G1 after mitosis. Collectively the study provides new insight into the roles of Nup2 and NupA during mitosis and in a surveillance mechanism that regulates nucleokinesis when mitotic defects occur after SAC fulfillment.
Optimization of a micronekton model with acoustic data
Authors: Lehodey Patrick , Conchon Anna , Senina Inna , Domokos Réka , Calmettes Beatriz , Jouanno Julien , Hernandez Olga , Kloser Rudy
Published: December 2014

In the pelagic foodweb, micronekton at the mid-trophic level (MTL) are one of the lesser known components of the ocean ecosystem despite being a major driver of the spatial dynamics of their predators, of which many are exploited species (e.g. tunas). The Spatial Ecosystem and Population Dynamics Model is one modelling approach that includes a representation of the spatial dynamics of several epi- and mesopelagic MTL functional groups. The dynamics of these groups are driven by physical (temperature and currents) and biogeochemical (primary production, euphotic depth) variables. A key issue to address is the parameterization of the energy transfer from the primary production to these functional groups. We present a method using in situ acoustic data to estimate the parameters with a maximum likelihood estimation approach. A series of twin experiments conducted to test the behaviour of the model suggested that in the ideal case, that is, with an environmental forcing perfectly simulated and biomass estimates directly correlated with the acoustic signal, a minimum of 200 observations over several time steps at the resolution of the model is needed to estimate the parameter values with a minimum error. A transect of acoustic backscatter at 38 kHz collected during scientific cruises north of Hawaii allowed a first illustration of the approach with actual data. A discussion followed regarding the various sources of uncertainties associated with the use of acoustic data in micronekton biomass.
Supervised learning from human performance at the computationally hard problem of optimal traffic signal control on a network of junctions
Authors: Box Simon
Published: December 2014

Optimal switching of traffic lights on a network of junctions is a computationally intractable problem. In this research, road traffic networks containing signallized junctions are simulated. A computer game interface is used to enable a human ‘player’ to control the traffic light settings on the junctions within the simulation. A supervised learning approach, based on simple neural network classifiers can be used to capture human player's strategies in the game and thus develop a human-trained machine control (HuTMaC) system that approaches human levels of performance. Experiments conducted within the simulation compare the performance of HuTMaC to two well-established traffic-responsive control systems that are widely deployed in the developed world and also to a temporal difference learning-based control method. In all experiments, HuTMaC outperforms the other control methods in terms of average delay and variance over delay. The conclusion is that these results add weight to the suggestion that HuTMaC may be a viable alternative, or supplemental method, to approximate optimization for some practical engineering control problems where the optimal strategy is computationally intractable.
Scaling probabilistic models of genetic variation to millions of humans
Authors: Gopalan Prem , Hao Wei , Blei David M. , Storey John D.
Published: December 2014

One of the major goals of population genetics is to quantitatively understand variation of genetic polymorphisms among individuals. To this end, researchers have developed sophisticated statistical methods to capture the complex population structure that underlies observed genotypes in humans, and such methods have been effective for analyzing modestly sized genomic data sets. However, the number of genotyped humans has grown significantly in recent years, and it is accelerating. In aggregate about 1M individuals have been genotyped to date. Analyzing these data will bring us closer to a nearly complete picture of human genetic variation; but existing methods for population genetics analysis do not scale to data of this size. To solve this problem we developed TeraStructure. TeraStructure is a new algorithm to fit Bayesian models of genetic variation in human populations on tera-sample-sized data sets (1012observed genotypes, e.g., 1M individuals at 1M SNPs). It is a principled approach to Bayesian inference that iterates between subsampling locations of the genome and updating an estimate of the latent population structure of the individuals. On data sets of up to 2K individuals, TeraStructure matches the existing state of the art in terms of both speed and accuracy. On simulated data sets of up to 10K individuals, TeraStructure is twice as fast as existing methods and has higher accuracy in recovering the latent population structure. On genomic data simulated at the tera-sample-size scales, TeraStructure continues to be accurate and is the only method that can complete its analysis.

Software

TeraStructure is available for download athttps://github.com/premgopalan/terastructure.

Funding

This research was supported in part by NIH grant R01 HG006448 and ONR grant N00014-12-1-0764.
Large unburnt areas, not small unburnt patches, are needed to conserve avian diversity in fire‐prone landscapes
Authors: Berry Laurence E. , Lindenmayer David B. , Driscoll Don A.
Published: December 2014

Mitigating the impacts of large‐scale fires on biodiversity is becoming increasingly important as their frequency increases. In response, fire managers have engaged with the concept that retaining small unburnt residual areas of vegetation within extensively burnt landscapes may facilitate biodiversity conservation. However, it remains uncertain how the size and isolation of these unburnt residuals influence faunal distributions, persistence and recovery following fire.

We used a replicated observation study to test bird responses to the size and isolation of unburnt residuals in a mallee woodland area recently burnt by a 28 000 ha wildfire in southern Australia. The scale of our study provided a rare opportunity to consider the responses of large mobile organisms to fire‐induced habitat fragmentation. Within five replicated spatial blocks, we crossed two levels of isolation with large (5–7 ha) and small (1–3 ha) unburnt patches and matrix sites burnt 5 years previously. We compared these site types to six continuous (non‐fragmented) unburnt sites. We surveyed each site on eight occasions.

Most birds occurred more frequently in unburnt habitat beyond the extent of the fire. Bird responses to the availability and spatial distribution of unburnt remnants within the fire were largely influenced by their ability to use the recently burnt matrix. Occurrence of five species was higher in unburnt residuals when more of the landscape within 500 m was burnt.

A fire refuge effect may be likely for two competitive species that occurred more frequently in unburnt residuals than in the burnt matrix or continuous unburnt habitat. For the weebill, recolonization following fire was likely to occur gradually over time from ex situ sources.

Synthesis and applications. To maintain avian diversity in fire‐prone landscapes, our results suggest a need to shift management focus from creating networks of small unburnt patches towards preserving large, intact areas of habitat. However, five species common to the burnt matrix preferentially selected residual patches when unburnt resources were locally scarce. Therefore, to benefit birds, land managers should limit the extent of applied burns and use narrow burns. When planning large burns, practitioners should consider that a number of species will remain absent from the landscape for several decades.
The Active Audience? Gurus, Management Ideas and Consumer Variability
Authors: Groß Claudia , Heusinkveld Stefan , Clark Timothy
Published: December 2014

This study draws on an active audience perspective to develop a better understanding of mass audiences' attraction towards popular management ideas. It focuses on audience members' own experiences and, in particular, what audience activities actually play a role in shaping mass attraction, and how the deployment of these activities may vary. Analysing 65 in‐depth interviews with management practitioners in their role as audience members of guru seminars, the authors identify different key consumption activities, and explain how individual management practitioners may shift in consumption orientation throughout the communication process. This paper argues that such a broader and more dynamic understanding of consumption activity is essential in understanding the success and impact of management ideas, and opens several fruitful research directions.
Surgically avertable burden of obstetric conditions in low‐ and middle‐income regions: a modelled analysis
Authors: Higashi H , Barendregt JJ , Kassebaum NJ , Weiser TG , Bickler SW , Vos T
Published: December 2014

Objective

To quantify the burden of maternal and neonatal conditions in low‐ and middle‐income countries (LMICs) that could be averted by full access to quality first‐level obstetric surgical procedures.

Design

Burden of disease and epidemiological modelling.

Setting

LMICs from all global regions.

Population

The entire population in 2010.

Methods

We included five conditions in our analysis: maternal haemorrhage; obstructed labour; obstetric fistula; abortion1; and neonatal encephalopathy. Demographic and epidemiological data were obtained from the Global Burden of Disease 2010 study. We split the disability‐adjusted life years (DALYs) of these conditions into surgically ‘avertable’ and ‘non‐avertable’ burdens. We applied the lowest age‐specific fatality rates from all global regions to each LMIC region to estimate the avertable deaths, assuming that the differences of death rates between each region and the lowest rates reflect the gap in surgical care.

Main outcome measures

Deaths and DALYs avertable.

Results

Of the estimated 56.6 million DALYs (i.e. 56.6 million years of healthy life lost) of the selected five conditions, 21.1 million DALYs (37%) are avertable by full coverage of quality obstetric surgery in LMICs. The avertable burden in absolute term is substantial given the size of burden of these conditions in LMICs. Neonatal encephalopathy constitutes the largest portion of avertable burden (16.2 million DALYs) among the five conditions, followed by abortion (2.1 million DALYs).

Conclusions

Improving access to quality surgical care at first‐level hospitals could reduce a tremendous burden of maternal and neonatal conditions in LMICs.
A systematic review of essential obstetric and newborn care capacity building in rural sub‐Saharan Africa
Authors: Ni Bhuinneain GM , McCarthy FP
Published: December 2014

Background

Progress in maternal survival in sub‐Saharan Africa has been poor since the Millennium Declaration.

Objectives

This systematic review aims to investigate the presence and rigour of evidence for effective capacity building for Essential Obstetric and Newborn Care (EONC) to reduce maternal mortality in rural, sub‐Saharan Africa, where maternal mortality ratios are highest globally.

Search strategy

MEDLINE (1990–January 2014), EMBASE (1990–January 2014), and the Cochrane Library were included in our search. Key developing world issues of The Lancet and the British Journal of Obstetrics and Gynaecology, African Ministry of Health websites, and the WHO reproductive health library were searched by hand.

Selection criteria

Studies investigating essential obstetric and newborn care packages in basic and comprehensive care facilities, at community and institutional level, in rural sub‐Saharan Africa were included. Studies were included if they reported on healthcare worker performance, access to care, community behavioural change, and emergency obstetric and newborn care.

Data collection and analysis

Data were extracted and all relevant studies independently appraised using structured abstraction and appraisal tools.

Main results

There is moderate evidence to support the training of healthcare workers of differing cadres in the provision of emergency obstetric and newborn services to reduce institutional maternal mortality and case‐fatality rates in rural sub‐Saharan Africa. Community schemes that sensitise and enable access to maternal health services result in a modest rise in facility birth and skilled birth attendance in this rural setting.

Authors' conclusion

Essential Obstetric and Newborn Care has merit as an intervention package to reduce maternal mortality in rural sub‐Saharan Africa.
Molecular detection of invertebrate prey in vertebrate diets: trophic ecology ofCaribbean island lizards
Authors: Kartzinel Tyler R. , Pringle Robert M.
Published: December 2014

Understanding community assembly and population dynamics frequently requires detailed knowledge of food web structure. For many consumers, obtaining precise information about diet composition has traditionally required sacrificing animals or other highly invasive procedures, generating tension between maintaining intact study populations and knowing what they eat. We developed 16SmitochondrialDNAsequencing methods to identify arthropods in the diets of generalist vertebrate predators without requiring a blocking primer. We demonstrate the utility of these methods for a commonCaribbean lizard that has been intensively studied in the context of small island food webs:Anolis sagrei(a semi‐arboreal ‘trunk‐ground’ anole ecomorph). NovelPCRprimers were identified in silico and tested in vitro. Illumina sequencing successfully characterized the arthropod component of 168 faecalDNAsamples collected during three field trips spanning 12 months, revealing 217 molecular operational taxonomic units (mOTUs) from at least nine arthropod orders (includingAraneae,Blattodea,Coleoptera,Hemiptera,Hymenoptera,Isoptera,Lepidoptera andOrthoptera). Three mOTUs (one beetle, one cockroach and one ant) were particularly frequent, occurring in ≥50% of samples, but the majority of mOTUs were infrequent (180, or 83%, occurred in ≤5% of samples). Species accumulation curves showed that dietary richness and composition were similar between size‐dimorphic sexes; however, female lizards had greater per‐sample dietary richness than males. Overall diet composition (but not richness) was significantly different across seasons, and we found more pronounced interindividual variation inDecember than inMay. These methods will be generally useful in characterizing the diets of diverse insectivorous vertebrates.
Pregnancy‐related issues in women with systemic lupus erythematosus
Authors: Singh Abha G. , Chowdhary Vaidehi R.
Published: December 2014

While fertility is preserved in females with systemic lupus erythematosus (SLE), it is well established that pregnancy in these patients is associated with adverse maternal and fetal outcomes, including pregnancy loss, pre‐eclampsia, preterm delivery and intrauterine growth retardation, as well as neonatal mortality. Mechanisms underlying these adverse outcomes are poorly understood, and better understanding of these would allow development of targeted and personalized treatment strategies. Established risk factors for adverse pregnancy outcomes include active disease within 6 months prior to conception and during pregnancy, active nephritis, maternal hypertension, antiphospholipid antibodies and hypocomplementemia. While intensive monitoring is recommended, the comparative effectiveness of appropriate management strategies is unclear. While current strategies are able to achieve live births in 85–90% of pregnancies, certain aspects such as prevention of preterm birth, treatment of congenital heart block due to neonatal lupus and recurrent pregnancy loss despite best management, remains challenging. Pregnancy is also associated with an increased risk of flare of lupus, particularly in patients with active disease at time of conception or within 6 months prior to conception. Pregnant patients withSLEshould be followed in a high‐risk obstetric clinic, and care should be closely coordinated between the obstetrician and rheumatologist.
Serum anti‐Müllerian hormone and ovarian morphology assessed by magnetic resonance imaging in response to acupuncture and exercise in women with polycystic ovary syndrome: secondary analyses of a randomized controlled trial
Authors: Leonhardt Henrik , Hellström Mikael , Gull Berit , Lind Anna‐Karin , Nilsson Lars , Janson Per Olof , Stener‐Victorin Elisabet
Published: December 2014

Objective

To investigate whether electro‐acupuncture or physical exercise influence serum anti‐Müllerian hormone (AMH), antral follicle count (AFC) or ovarian volume in women with polycystic ovary syndrome (PCOS).

Design

Secondary analyses of a prospective, randomized controlled clinical trial.

Setting

University Hospital, Sweden.

Patients

Seventy‐four women with PCOS recruited from the general population.

Interventions

Women with PCOS were randomized to 16 weeks of electro‐acupuncture (14 treatments), exercise (at least three times/week), or no intervention.

Main outcome measures

Serum AMH recorded at baseline, after 16 weeks of intervention, and at follow up at 32 weeks. AFC, and ovarian volume assessed by magnetic resonance imaging at baseline and at follow up at 32 weeks.

Results

After 16 weeks of intervention, serum levels of AMH were significantly decreased in the electro‐acupuncture group by 17.5% (p < 0.001), and differed from the change in the exercise group. AMH remained decreased by 15% (p = 0.004) also at follow up at 32 weeks, but did not differ from the exercise or the no intervention groups. There was a decrease by 8.5% (p = 0.015) in ovarian volume between baseline and follow up in the electro‐acupuncture group, and by 11.7% (p = 0.01) in AFC in the physical exercise group. No other variables were affected.

Conclusions

This study is the first to demonstrate that acupuncture reduces serum AMH levels and ovarian volume. Physical exercise did not influence circulating AMH or ovarian volume. Despite a within‐group decrease in AFC, exercise did not lead to a between‐group difference.
Live music reduces stress levels in very low‐birthweight infants
Authors: Schwilling Diana , Vogeser Michael , Kirchhoff Fabian , Schwaiblmair Frauke , Boulesteix Anne‐Laure , Schulze Andreas , Flemmer Andreas W.
Published: December 2014

Aim

Music might benefit preterm infants in stressful, intensive care environments. However, data on stress level indicators, determined by salivary cortisol levels, are scarce. We evaluated the effect of live harp music on the stress level indicators of preterm infants in a neonatal intensive care unit (NICU).

Methods

We exposed 20 stable preterm infants to music for 15 min on three consecutive days. Saliva was collected before the music was played and 25 min and 4 h after it ended. Salivary cortisol levels were measured by liquid chromatography–tandem mass spectrometry and vital signs, oxygen saturation, bradycardia, apnoeas and oxygen desaturations were recorded. Pain levels were assessed by the Bernese Pain Scale for Neonates.

Results

Salivary cortisol was significantly lower 25 min (18.9 nmol/L [3.9–35.6] p = 0.001) and 4 h after music (17.4 nmol/L [3.9–35.3] p = 0.003) than at baseline 4 h before exposure (19.5 nmol/L [7.2–51.1]). After music, the number of apnoeas and oxygen desaturations was significantly reduced on all three, days and the number of bradycardia episodes on day one. Pain scores significantly improved after music on all 3 days.

Conclusion

Exposure to live music reduced salivary cortisol and had beneficial effects on the physiologic parameters of stable preterm infants in a NICU.
Assessing the tongue colour of newly born infants may help to predict the need for supplemental oxygen in the delivery room
Authors: Dawson JA , Ekström A , Frisk C , Thio M , Roehr CC , Kamlin COF , Donath SM , Davis PG ,   the Giraffe Study Group
Published: December 2014

Aim

It takes several minutes for infants to become pink after birth. Preductal oxygen saturation (SpO2) measurements are used to guide the delivery of supplemental oxygen to newly born infants, but pulse oximetry is not available in many parts of the world. We explored whether the pinkness of an infant's tongue provided a useful indication that supplemental oxygen was required.

Methods

This was a prospective observational study of infants delivered by Caesarean section. Simultaneous recording of SpO2 and visual assessment of whether the tongue was pink or not was made at 1–7 and 10 min after birth.

Results

The 38 midwives and seven paediatric trainees carried out 271 paired assessments on 68 infants with a mean (SD) birthweight of 3214 (545) grams and gestational age of 38 (2) weeks. When the infant did not have a pink tongue, this predicted SpO2 of <70% with a sensitivity of 26% and a specificity of 96%.

Conclusion

Tongue colour was a specific but insensitive sign that indicated when SpO2 was <70%. When the tongue is pink, it is likely that an infant has an SpO2 of more than 70% and does not require supplemental oxygen.
Central line bloodstream infections can be reduced in newborn infants using the modified Seldinger technique and care bundles of preventative measures
Authors: Arnts IJJ , Schrijvers NM , van der Flier M , Groenewoud JMM , Antonius T , Liem KD
Published: December 2014

Aim

There has been no evidence to show whether care bundles of preventive measures reduce central line‐associated bloodstream infection (CLABSI) in peripherally inserted central catheters using the modified Seldinger technique, which requires more specific skills than the traditional technique. The aim of this study was to address that gap in our knowledge and to determine whether other variables influenced the outcome.

Methods

This prospective observational study was conducted on a neonatal intensive care unit. We observed the incidence of CLABSI in 45 newborn infants with peripheral catheters before the introduction of bundles of preventative measures and 88 infants after the introduction.

Results

Laboratory‐confirmed CLABSI decreased after the introduction of the bundles, from 12.9 per 1000 days to 4.7/1000 days (p = 0.09). When we combined the rates for laboratory‐confirmed CLABSI and clinical CLABSI in a survival analysis, the incidence reduced significantly after introduction of the bundles (p = 0.02). There were no other variables that affected the outcome.

Conclusion

Cost‐effective care bundles reduced CLABSI in peripherally inserted central catheters using the modified Seldinger technique, despite the specific insertion skills that were required. The bundles of preventative measures may increase healthcare professionals’ awareness of the need to care for central catheters and reduce CLABSI infections.
Novel Glycoconjugate of 8‐Fluoro Norfloxacin Derivatives as Gentamicin‐resistant Staphylococcus aureus Inhibitors: Synthesis and Molecular Modelling Studies
Authors: Azad Chandra S. , Bhunia Shome S. , Krishna Atul , Shukla Praveen K. , Saxena Anil K.
Published: December 2014

Antibiotic resistance has been the subject of interest in clinical practice due to high prevalence of antibiotic‐resistant pathogenic organisms. In view of the prevalence of lesser resistance in antibiotics belonging to aminoglycoside class of compounds viz. Food and Drug Administration‐approved gentamicin for the treatment of Staphylococcus infections, which also has instances of resistance in the clinical isolates of Staphylococcus aureus, a series of novel glycoconjugates of 8‐fluoro norfloxacin analogues with high regio‐selectivity by employing copper (I)‐catalyzed 1, 3‐dipolar cycloaddition of 1‐O‐propargyl monosaccharides has been synthesized and evaluated for the antibacterial activity against gentamicin resistance Staphylococcus aureus. Among these compounds, the compound 10g showed better antibacterial activity (MIC = 3.12 μg/ml) than gentamicin (Escherichia coli (12.5 μg/ml), Staphylococcus aureus (6.25 μg/ml) and Klebsiella pneumonia (6.25 μg/ml), including gentamicin resistant (>50 μg/ml) strain in vitro). The docking studies suggest DNA gyrase of Staphylococcus aureus as a probable target for the antibacterial action of compound 10g.
Differences between disease-associated endoplasmic reticulum aminopeptidase 1 (ERAP1) isoforms in cellular expression, interactions with tumour necrosis factor receptor 1 (TNF-R1) and regulation by cytokines
Authors: Yousaf N , Low W Y , Onipinla A , Mein C , Caulfield M , Munroe P B , Chernajovsky Y
Published: December 2014

Endoplasmic reticulum aminopeptidase 1 (ERAP1) processes peptides for major histocompatibility complex (MHC) class I presentation and promotes cytokine receptor ectodomain shedding. These known functions of ERAP1 may explain its genetic association with several autoimmune inflammatory diseases. In this study, we identified four novel alternatively spliced variants of ERAP1 mRNA, designated as ΔExon-11, ΔExon-13, ΔExon-14 and ΔExon-15. We also observed a rapid and differential modulation of ERAP1 mRNA levels and spliced variants in different cell types pretreated with lipopolysaccharide (LPS). We have studied three full-length allelic forms of ERAP1 (R127-K528, P127-K528, P127-R528) and one spliced variant (ΔExon-11) and assessed their interactions with tumour necrosis factor receptor 1 (TNF-R1) in transfected cells. We observed variation in cellular expression of different ERAP1 isoforms, with R127-K528 being expressed at a much lower level. Furthermore, the cellular expression of full-length P127-K528 and ΔExon-11 spliced variant was enhanced significantly when co-transfected with TNF-R1. Isoforms P127-K528, P127-R528 and ΔExon-11 spliced variant associated with TNF-R1, and this interaction occurred in a region within the first 10 exons of ERAP1. Supernatant-derived vesicles from transfected cells contained the full-length and ectodomain form of soluble TNF-R1, as well as carrying the full-length ERAP1 isoforms. We observed marginal differences between TNF-R1 ectodomain levels when co-expressed with individual ERAP1 isoforms, and treatment of transfected cells with tumour necrosis factor (TNF), interleukin (IL)-1β and IL-10 exerted variable effects on TNF-R1 ectodomain cleavage. Our data suggest that ERAP1 isoforms may exhibit differential biological properties and inflammatory mediators could play critical roles in modulating ERAP1 expression, leading to altered functional activities of this enzyme.
Migration of Bursaphelenchus xylophilus in cortical and xylem axial resin canals of resistant pines
Authors: Son J. A. , Matsushita N. , Hogetsu T.
Published: December 2014

Migration of the pine wood nematode (PWN), Bursaphelenchus xylophilus, in susceptible and resistant pines was investigated at the tissue level. PWN was inoculated onto the top cross‐cut surface of 20‐cm stem cuttings of susceptible Pinus thunbergii and resistant pines (P. strobus, P. rigida and P. thunbergii of a resistant family Namikata‐(t)‐73 (half‐sib)). PWNs were mainly distributed in cortical resin canals of susceptible P. thunbergii down to 15 cm from the inoculated surface by 6 h after inoculation (HAI) and all tissues (including cortical and xylem resin canals) down to the bottom at 192 HAI. In P. strobus, P. rigida and P. thunbergii family Namikata‐(t)‐73 (half‐sib), PWN was distributed in cortical resin canals down to 5 cm by 6 HAI and down to the base at 192 HAI. However, the distribution of PWN in xylem resin canals of the resistant pines was restricted near inoculated surfaces down to 5 cm, even at 192 HAI. These results demonstrated that migration of PWN in resistant pines was slowed in cortical resin canals and restricted in xylem axial resin canals, features which may be associated with the resistance.