bluuebunny/crossref_metadata_2025 huggingface dataset:
Rheological Properties of Barite Sediments in Water-Based Drilling Fluids
Authors: Vrålstad Torbjørn , Skorpa Ragnhild , Saasen Arild
Published: September 2018

When a drilling fluid column remains static over a timeframe of several years, the drilling fluid separates into different sediment phases due to gravity separation. These heavy sediments, entitled “settled barite”, are the cause of significant operational problems several years after drilling.

An important problem caused by settled barite occurs when performing casing cut-and-pull operations during slot recovery and well abandonment: the casing is “stuck” due to the sediments in the annulus outside the casing. The consistency and rheological properties of the sediments determine how easily the casing is removed.

In this paper, we report a preliminary study were we have artificially prepared gravity sediment phases for two different types of water-based drilling fluids; one KCl/polymer-based fluid and one bentonite-based fluid. By studying the rheological properties of the obtained sediment phases, we see that there are considerable differences between the sediments for these different drilling fluids.
Effect of MWCNT and MWCNT Functionalized -OH and -COOH Nanoparticles in Laboratory Water Based Drilling Fluid
Authors: Alvi Muhammad Awais Ashfaq , Belayneh Mesfin , Saasen Arild , Fjelde Kjell Kåre , Aadnøy Bernt S.
Published: September 2018

In recent years, the application of nanomaterial has been attracting the oil and gas industry. Nanomaterials research results show an improving performance of cement, drilling fluid and enhanced oil recovery.

In this paper, the effect of multi-walled carbon nanotube (MWCNT) and MWCNT functionalized with ligands–OH and - COOH nanoparticles on laboratory drilling fluids formulated from bentonite, KCL, Carboxymethyl cellulose (CMC) and xanthan gum (XG) was studied. The formulations and tests were performed at room temperature.

The results show that addition of 0.0095wt.% of MWCNT, MWCNT-OH and MWCNT-COOH nanoparticles in CMC/bentonite system decreases the filtrate-loss by 8.6 %, 7.1 % and 17.9 % respectively. These particles also decreased the coefficient of friction by 34 %, 37 % and 33 % respectively. In xanthan gum drilling fluid, 0.019wt%. MWCNT reduced the friction coefficient by 38 %.
On the Sequence of Large Waves From Field Data
Authors: Santoro Anita , Arena Felice , Guedes Soares Carlos
Published: September 2018

The present work focuses on large wave groups, in particular the succession of three waves, i.e. the largest one and the preceding and following ones, in presence of bimodal spectra. Results highlight that the profile is influenced by the dominant component, in the case of swell or wind sea dominated fields. In general, troughs amplitudes attain larger values than crests amplitudes when considering the waves preceding and following the largest crest. Moreover, the average profile of the three largest waves is generally symmetric about the central crest. The spectrum influences the largest waves in a wave group, in particular the greater the wind sea energy, compared to the swells energy content, the bigger the crests and troughs amplitudes of the preceding and following wave.
Performance of a Wave-Energy-Converter Array Operating Under Model-Predictive Control Based on a Convex Formulation
Authors: Zhong Qian , Yeung Ronald W.
Published: September 2018

Economics decision drives the operation of ocean-wave energy converters (WEC) to be in a “farm mode”. Control strategy developed for a WEC array will be of high importance for improving the aggregate energy extraction efficiency of the whole system. Model-predictive control (MPC) has shown its strong potential in maximizing the energy output in devices with hard constraints on operation states and machinery inputs (See Ref. [1–3]). Computational demands for using MPC to control an array in real time can be prohibitive. In this paper, we formulate the MPC to control an array of heaving point absorbers, by recasting the optimization problem for energy extraction into a convex Quadratic Programming (QP) problem, the solution of which can be carried out very efficiently. Large slew rates are to be penalized, which can also guarantee the convexity of the QP and improve the computational efficiency for achieving the optimal solution. Constraints on both the states and the control input can be accommodated in this MPC method. Full hydro-dynamic interference effects among the WEC array components are taken into account using the theory developed in [4]. Demonstrative results of the application are presented for arrays of two, three, and four point absorbers operating at different incident-wave angles. Effects of the interacting waves on power performance of the array under the new MPC control are investigated, with simulations conducted in both regular and irregular seas. Heaving motions of individual devices at their optimal conditions are shown. Also presented is the reactive power required by the power takeoff (PTO) system of the array to achieve optimality.

We are pleased to contribute this article in celebration of our collegiality with Professor Bernard Molin on the occasion of his honoring symposium.
Pump Tower Loads in Spherical Tanks Onboard LNG Carriers Scaled by Characteristic Vessel Response
Authors: Slagstad Martin , Hanssen Finn-Christian W. , Rognebakke Olav
Published: September 2018

Fatigue of the pump tower structure is an important design aspect for spherical cargo tanks onboard liquid natural gas carriers. Current state-of-the art methodology for assessing these loads is based on a series of model tests carried out about 10 and 40 years ago. The last campaign recorded tower loads for several tank filling ratios, vessel headings and sea states. Long-term distributions of loads were established, and this required the development of a scaling methodology to estimate short-term load distributions for sea states outside the range of tested conditions. However, the scaling approach proved to be inadequate when put into use in projects. The present paper proposes a new and enhanced scaling method for short-term distribution of loads on the pump tower involving re-assessment of the model test results combined with new statistical treatment. The dynamic loads on the pump tower causing fatigue damage can be separated into loads due to sloshing and inertial loads. The sloshing loads are seen to correlate well with the amount of energy in the acceleration response spectrum of the tank in a frequency range in vicinity of the lowest natural sloshing frequency. A characteristic response variable is defined as the integrated energy in the acceleration response spectrum over one half octave band around the sloshing resonance frequency, and a functional relationship between the loads on the pump tower and this parameter is established. The results show that this model describes the observed pump tower loads well, especially for filling heights 30 to 70%. Some more scatter is observed for very low or high filling levels, but as these cause lower loads this is not of concern. The underlying model tests primarily focused on high sea states in order to reflect global trade. The proposed scaling methodology allows for robust extrapolation to lower sea states in a more accurate way than was previously possible. This is particularly useful to avoid overly conservative fatigue-load estimates for other applications such as FSRUs and FLNGs in more benign conditions.
Numerical and Experimental Analysis of a Hybrid Wind-Wave Offshore Floating Platform’s Hull
Authors: Hallak Thiago S. , Gaspar José F. , Kamarlouei Mojtaba , Calvário Miguel , Mendes Mário J. G. C. , Thiebaut Florent , Guedes Soares C.
Published: September 2018

This paper presents a study regarding a novel hybrid concept for both wind and wave energy offshore. The concept resembles a semi-submersible wind platform with a larger number of columns. Wave Energy Devices such as point absorbers are to be displayed around the unit, capturing wave energy while heaving and also enhancing the stability of the platform. In this paper, a first numerical study of the platform’s hull, without Wave Energy Converters, is carried out. Experiments in wave basin regarding the same unit have been conducted and the results are presented and compared to the numerical ones. Both stability and seakeeping performances are assessed and compared.
Shale As a Sealing Barrier Around Deep Wells
Authors: Fjær Erling , Larsen Idar
Published: September 2018

Well sections that have been completed with an open annulus between the casing and the rock are occasionally found to be sealed by shale that creeps in and closes the annulus. This process usually happens spontaneously, without deliberate actions from the operator, in weak rocks with high shale content. The phenomenon has been studied in a series of laboratory tests. The tests reveal that annulus pressure may play a significant role in the formation of a shale barrier. The study also shows that formation of the barrier implies damage and permanent deformation of the rock in a limited region around the hole. In the field, a shale barrier is hidden behind the casing and is not directly accessible. They are usually detected by sonic logging tools and verified by pressure communication tests. Interpretation of sonic signals from behind the casing is however challenging, and identification of shale barriers in the field is not trivial.
A Simple Procedure for the Prediction of the Collapse Pressure of Pipelines With Narrow and Long Corrosion Defects: Uncertainty and Sensibility Analysis
Authors: Oliveira Nara , Netto Theodoro
Published: September 2018

The collapse pressure of pipelines containing corrosion defects is usually predicted by deterministic methods, either numerically or through empirical formulations. The severity of each individual corrosion defect can be determined by comparing the differential pressure during operation with the estimated collapse pressure. A simple deterministic procedure for estimating the collapse pressure of pipes with narrow and long defects has been recently proposed by Netto (2010). This formulation was based on a combined small-scale experimental program and nonlinear numerical analyses accounting for different materials and defect geometries.

However, loads and resistance parameters have uncertainties which define the basic reliability problem. These uncertainties are mailyrelated to the geometric and material parameters of the pipe and the operational conditions.

This paper presents additional experimental tests on corroded pipes under external pressure. The collapse pressure calculated using the equation proposed by Netto (2010) is compared with this new set of experiments and also with test results available in open literature. These results are used to estimate the equation uncertainty. Finally, a sensitivity analysis is performed to identify how geometric parameters of the defects influence the reduction of collapse pressure.
Reliability Analysis of Short Term Mooring Tension of a Semi-Submersible System
Authors: Xu Sheng , Guedes Soares C. , Teixeira Ângelo P.
Published: September 2018

A detail procedure to study mooring line strength reliability is presented. A fully coupled analysis is carried out to get the mooring tensions of a deep water semi-submersible floating systems operated in 100 year wave condition in South China Sea. The ACER method is applied to predict the 3h extreme mooring tension, and the results are validated by global maximum method. The hydrodynamic sampling points are generated by Latin Hypercube Sampling technique. The 3h extreme mooring tension is calculated by the ACER method with 10 minutes fully coupled dynamic simulation for each sampling point. The Kriging meta model method is trained to predict 3h mooring extreme tension under the effects of random hydrodynamic drag coefficients. A reliability analysis is carried out by implementing Monte Carlo simulation with the random hydrodynamic drag coefficients and mooring breaking strength considered.
High Cycle Fatigue Damage Evaluation of Steel Pipelines Based on Microhardness Changes During Cyclic Loads: Part II
Authors: Drumond Geovana , Pinheiro Bianca , Pasqualino Ilson , Roudet Francine , Chicot Didier
Published: September 2018

The hardness of a material shows its ability to resist to microplastic deformation caused by indentation or penetration and is closely related to the plastic slip capacity of the material. Therefore, it could be significant to study the resistance to microplastic deformations based on microhardness changes on the surface, and the associated accumulation of fatigue damage. The present work is part of a research study being carried out with the aim of proposing a new method based on microstructural changes, represented by a fatigue damage indicator, to predict fatigue life of steel structures submitted to cyclic loads, before macroscopic cracking. Here, Berkovich indentation tests were carried out in the samples previously submitted to high cycle fatigue (HCF) tests. It was observed that the major changes in the microhardness values occurred at the surface of the material below 3 μm of indentation depth, and around 20% of the fatigue life of the material, proving that microcracking is a surface phenomenon. So, the results obtained for the surface of the specimen and at the beginning of the fatigue life of the material will be considered in the proposal of a new method to estimate the fatigue life of metal structures.
Energy Content Analysis of Closed Basin Wave Simulation Using Linear and Nonlinear Fourier Analysis
Authors: Mohtat Ali , Yim Solomon C. , Osborne Alfred R.
Published: September 2018

This study focuses on the computation and analysis of the energy content of a wave train and the influence of nonlinear components, such as nonlinear wave profile as in Stokes wave and phased locked breathers, on the content. To this end, an overview of a state-of-the-art nonlinear Fourier analysis tools for the nonlinear Schrödinger equation is presented. Experimental measurements from a set of performance tests of the directional wave basin at Oregon State University were analyzed using this tool and the energy contents, both from the linear spectrum and nonlinear spectrum, were calculated. The deviation of the energy content from linear analysis and its relationship to the level of nonlinearity of the wave train is investigated. The Benjamin-Feir parameter presents the degree of nonlinearity of the wave train. An increasing energy deviation was observed for increasing nonlinearity of the wave field. Spatial evolution of such behavior is also investigated. It was confirmed that the significant difference from the linear energy is due to increase in the nonlinear components and the more distance the wave train could travel (without substantial dissipation) the more erratic and more significant energy deviations were observed.
A Unified Approach for Estimating of the Drag Coefficient in Offshore Structures in Presence of Bio-Colonization
Authors: Bakhtiari Arash , Schoefs Franck , Ameryoun Hamed
Published: September 2018

Due to increase of global demand for renewable energies, assessment of environmental forces become an important aspect of offshore structures which is the key to ensure optimized and reliable development of this industry. The present study aims to bring out an integrated approach to drag coefficient estimation for circular cylinders covered by biocolonization. Hard and long flapping (Kelp) species were chosen as the study area to demonstrate the effect of biofouling. An integrated approach including the percentage of cover, surface roughness ratio, biofouling species, and aggregating pattern was employed to investigate the steady state drag force coefficient. Several experimental data were collected from previous researchers considering afore-mentioned parameters.

This paper proposes two independent equations for hard and long flapping biofouling using regression analysis method. Both equations were compared with experimental data; a multivariate statistical analysis by Taylor diagram was also performed resulting in reasonable values.

It is worth mentioning that the present work is part of a wider study concerning the effects of biofouling components on the hydrodynamic forces of structures such as jackets and floating offshore structures. The first part of the study considered the investigation of the existing data.
On Efficient Long-Term Extreme Response Estimation for a Moored Floating Structure
Authors: Lim HyeongUk , Manuel Lance , Low Ying Min
Published: September 2018

This study investigates the use of efficient surrogate model development with the help of polynomial chaos expansion (PCE) for the prediction of the long-term extreme surge motion of a simple moored offshore structure. The structure is subjected to first-order and second-order (difference-frequency) wave loading. Uncertainty in the long-term response results from the contrasting sea state conditions, characterized by significant wave height, Hs, and spectral peak period, Tp, and their relative likelihood of occurrence; these two variables are explicitly included in the PCE-based uncertainty quantification (UQ). In a given sea state, however, response simulations must be run for any sampled Hs and Tp; in such simulations, typically, a set of random phases (and deterministic amplitudes) define a wave train consistent with the defined sea state. These random phases for all the frequency components in the wave train introduce additional uncertainty in the simulated waves and in the response. The UQ framework treats these two sources of uncertainty — from Hs and Tp on the one hand, and the phase vector on the other — in a nested manner that is shown to efficiently yield long-term surge motion extreme predictions consistent with more expensive Monte Carlo simulations, which serve as the truth system. Success with the method suggests that similar inexpensive surrogate models may be developed for assessing the long-term response of various offshore structures.
On the Development of an Efficient Surrogate Model for Predicting Long-Term Extreme Loads on a Wave Energy Converter
Authors: Nguyen Phong T. T. , Manuel Lance , Coe Ryan G.
Published: September 2018

Accurate prediction of long-term extreme loads is essential for the design of wave energy converters (WECs), but it is also computationally demanding due to the low probabilities associated with their occurrence. While a full long-term probabilistic analysis using integration over all sea states or Monte Carlo Simulation (MCS) may be used, these methods can be prohibitively expensive when individual response simulations are complex and time-consuming. The application of polynomial chaos expansion (PCE) schemes to allow the propagation of uncertainty from the environment through the stochastic sea surface elevation process and ultimately to WEC extreme load response prediction is the focus in this study. A novel approach that recognizes the role of long-term ocean climate uncertainty (in sea state variables like significant wave height and spectral peak period) as well as short-term response uncertainty arising from irregular wave trains is presented and applied to a single-body point-absorber WEC device model. Stochastic simulation results in time series realizations of various response processes for the case-study WEC. We employ environmental data from a possible deployment site in Northern California (NDBC 46022) to assess long-term loads. MCS computations are also performed and represent the “truth” system against which the efficiency and accuracy of the PCE surrogate model is assessed. Results suggest that the PCE approach requires significantly less effort to obtain comparable estimates to MCS.
Casing Collapse Design Using Structural Reliability Analysis for a Subsea Well on the Norwegian Continental Shelf
Authors: Buchmiller David , Bjørset Arve , Hørte Torfinn , Pettersen Sune
Published: September 2018

Casing collapse capacity was identified by Statoil as a critical operational parameter on one of its fields in production. This facilitated the need to re-evaluate the overall well design, specifically the production casing’s collapse capacity. Studies were performed to analyze and objectively increase the documented casing collapse capacity, while maintaining the safety level.

Initially, the casing collapse capacity was evaluated using API TR 5C3 / ISO 10400, with insufficient capacity being documented. In order to investigate further, physical material testing and collapse testing were performed. Detailed finite element analysis was used to evaluate the casing collapse capacity, given well specific input parameters. The four critical parameters of axial load, casing ovality, casing wear, and temperature-dependent material properties were identified and the importance of each parameter was mapped. Using the testing results and the finite element models as a basis, structural reliability analysis (SRA) was applied to calculate the probability of failure for casing collapse of the production casing as a function of the differential pressure.

The SRA provided results for the spread of the field and for individual wells given specific input on the key parameters of casing ovality, wear and temperature. At the selected target reliability level, the SRA results showed a higher collapse capacity of the production casing relative to conservative calculations commonly used from API TR 5C3 / ISO 10400 for well design.

Applying SRA to well design, specifically collapse evaluations, has proven useful in concluding on the probability of failure. The SRA has transformed improved knowledge from testing and measurements to reduced uncertainty and a corresponding reduction in the failure probability. The potential over-conservatism in the conventional deterministic analysis is then avoided, while maintaining the overall safety level. The SRA results were used to assist in the risk evaluation resulting in an allowance for continued production on existing wells.
User Interface Design Guidelines for Marine Autonomous Operations Involving a Large Number of Actors, Devices and Sensors
Authors: Poranen Hanna , Marafioti Giancarlo , Johansen Gorm , Sæter Eivind
Published: September 2018

User interface (UI) is a platform that enables interaction between a human and a machine, a visual part of an information device, such as a computer or software, which user interacts with. A good user interface design makes operating a machine efficient, safe and user friendly in a way that gives the desired result.

This paper describes a set of guidelines defined for marine autonomous operations where many actors, devices and sensors are interacting. The UI should manage and present in a user-friendly manner a large amount of data, ensuring situation awareness for the operator/user. The design guidelines of the user interface consist of both a work process part and a content part, also called user experience design (UX). The work process consists of four sections: manage, plan, operate and evaluate, while the content part focuses on how to show the information. Both parts will be detailed and discussed and can be taken as a reference for designing user interfaces in particular for marine autonomous operations.
Exploring Distributional Properties of the Maximum Wave Height in a Sea State
Authors: Rodríguez Germán , Guedes Soares Carlos , Borge José Carlos Nieto
Published: September 2018

Location, dispersion, and asymmetry variability of the probability distribution of the maximum wave height from a set of N individual wave heights are examined in terms of the spectral peakedness and the duration of the sea states through the use of robust statistical parameters. The capability of various empirical and theoretical models to reproduce the observed features is also explored. The study is based on the analysis of numerically simulated Gaussian wave records with given target spectra to fulfill the long duration and stationarity jointly required conditions, seldom found in nature. Results indicate a clear dependence of the probability distribution structure and location on the record length and the spectral narrowness. Furthermore, it is observed that theoretical models based on the statistical independence of individual waves in a sea state and the knowledge of its population distribution assumptions are not able to characterize the structure and variations induced by these factors on the empirical distribution. However, the observed features can be reproduced by a simple empirical model depending on the sample quartiles.
Structural contributions to phantom partial generation in the piano
Authors: Moore Thomas R. , Neldner Lauren M. , Rokni Eric
Published: September 2018

The results of experiments designed to determine the origin of the anomalous frequency components in the sound of the piano commonly referred to as phantom partials are reported. It is shown that these overtones, which occur at the sum and difference frequencies associated with the transverse string motion, are produced by nonlinearities in both the string and the wooden components of the piano. However, the contribution from the string is significantly smaller than the contributions from other components.
Maturity-Related Differences in Systemic Pulmonary and Localized Fatigue Threshold Among Youth Male Athletes
Authors: Beyer Kyle S. , Stout Jeffrey R. , Redd Michael J. , Baker Kayla M. , Bergstrom Haley C. , Hoffman Jay R. , Fukuda David H.
Published: September 2018

Purpose: To examine the reliability and the maturity-related differences of fatigue thresholds (FTs) among youth males. Methods: Twenty-nine youth males (11–17 y) completed 2 ramp exercise tests on a cycle ergometer. Systemic FTs were calculated from gas exchange and ventilation variables. Localized FTs were calculated from electromyography and near-infrared spectroscopy of the vastus lateralis. All FTs were determined using the maximal distance method and expressed relative to maximal oxygen consumption. All participants were grouped according to the number of years from peak height velocity into PRE- (< −1.5 y), PERI- (−1.5 to +1.5 y) and POST- (> +1.5 y) peak height velocity. Reliability was assessed with intraclass correlation coefficients, and differences between groups were assessed with analysis of variance and Cohen’s d coefficients. Results: Analysis of variance revealed significant group differences with PRE having significantly greater systemic pulmonary FTs than POST, while localized muscular FTs were significantly greater in PRE when compared with PERI and POST. All FTs exhibited excellent reliability (intraclass correlation coefficient > .75) in all maturity groups. Conclusion: Maturity status appears to influence the onset of FTs among youth male athletes, with FTs occurring later in younger athletes. Furthermore, all FTs were reliable measures regardless of maturity.
Arrestins and G proteins in cellular signaling: The coin has two sides
Authors: Gurevich Vsevolod V. , Gurevich Eugenia V.
Published: September 2018

Arrestins maintain a balance between G protein– and arrestin-dependent ERK activation (Luttrell
et al.
, in 25 September 2018 issue).
New connections: Integrated search for therapies
Authors: Ferrarelli Leslie K.
Published: September 2018

Integrating “omics” analyses with developmental models reveals therapeutic targets for aggressive cancers.
Autoinducer 2 (AI-2) Production by Nontypeable Haemophilus influenzae 86-028NP Promotes Expression of a Predicted Glycosyltransferase That Is a Determinant of Biofilm Maturation, Prevention of Dispersal, and Persistence
In Vivo
Authors: Pang Bing , Armbruster Chelsie E. , Foster Gayle , Learman Brian S. , Gandhi Uma , Swords W. Edward
Published: September 2018

Nontypeable
Haemophilus influenzae
(NT
Hi
) is an extremely common human pathobiont that persists on the airway mucosal surface within biofilm communities, and our previous work has shown that NT
Hi
biofilm maturation is coordinated by the production and uptake of autoinducer 2 (AI-2) quorum signals. To directly test roles for AI-2 in maturation and maintenance of NT
Hi
biofilms, we generated an NT
Hi
86-028NP mutant in which
luxS
transcription was under the control of the
xylA
promoter (NT
Hi
86-028NP
luxS xylA
::
luxS
), rendering AI-2 production inducible by xylose.
Characterization of a Threonine-Rich Cluster in Hepatitis C Virus Nonstructural Protein 5A and Its Contribution to Hyperphosphorylation
Authors: Schenk Christian , Meyrath Max , Warnken Uwe , Schnölzer Martina , Mier Walter , Harak Christian , Lohmann Volker
Published: September 2018

Hepatitis C virus infections affect 71 million people worldwide and cause severe chronic liver disease. Recently, efficient antiviral therapies have been established, with inhibitors of nonstructural protein NS5A as a cornerstone. NS5A is a central regulator of HCV replication and assembly but is still enigmatic in its molecular functions. It exists in two phosphoisoforms, p56 and p58. We identified a phosphopeptide exclusively found in p58 and analyzed the determinants involved in phosphorylation of this region. We found evidence for very different phosphorylation patterns resulting in p58. These results challenge the concept of p58 being a homogenous species of NS5A molecules phosphorylated at the same positions and argues for at least two independently phosphorylated variants showing the same electrophoretic mobility, likely serving different functions.
Spatiotemporal Distribution and Evolution of the A/H1N1 2009 Pandemic Influenza Virus in Pigs in France from 2009 to 2017: Identification of a Potential Swine-Specific Lineage
Authors: Chastagner Amélie , Hervé Séverine , Bonin Emilie , Quéguiner Stéphane , Hirchaud Edouard , Henritzi Dinah , Béven Véronique , Gorin Stéphane , Barbier Nicolas , Blanchard Yannick , Simon Gaëlle
Published: September 2018

Pigs are a “mixing vessel” for influenza A viruses (IAVs) because of their ability to be infected by avian and human IAVs and their propensity to facilitate viral genomic reassortment events. Also, as IAVs may evolve differently in swine and humans, pigs can become a reservoir for old human strains against which the human population has become immunologically naive. Thus, viruses from the novel swine-specific H1N1pdm genogroup may continue to diverge from seasonal H1N1pdm strains and/or from other H1N1pdm viruses infecting pigs and lead to the emergence of viruses that would not be covered by human vaccines and/or swine vaccines based on antigens closely related to the original H1N1pdm virus. This discovery confirms the importance of encouraging swine IAV monitoring because H1N1pdm swine viruses could carry an increased risk to both human and swine health in the future as a whole H1N1pdm virus or gene provider in subsequent reassortant viruses.
Analyses of a Ceftazidime-Avibactam-Resistant
Citrobacter freundii
Isolate Carrying
bla
KPC-2
Reveals a Heterogenous Population and Reversible Genotype
Authors: Castanheira Mariana , Arends S. J. Ryan , Davis Andrew P. , Woosley Leah N. , Bhalodi Amira A. , MacVane Shawn H.
Published: September 2018

The development of ceftazidime-avibactam resistance among KPC-producing isolates during treatment with this agent has been reported. Usually isolates that become resistant have a mutated
bla
KPC
gene that confers resistance to ceftazidime-avibactam and susceptibility to meropenem. We report a
Citrobacter freundii
isolate that developed ceftazidime-avibactam resistance due to mutations within the coding region of the
bla
KPC-2
Ω-loop previously reported; however, in this case, only 11% of the whole-genome sequencing reads had mutations, making this alteration difficult to detect and the treatment of these isolates more challenging. In addition to
bla
KPC
, the initial and the follow-up patient isolates displayed hyperexpression of the AcrAB-TolC efflux system and disruption of the outer membrane protein (OMP) OmpF, which contribute to carbapenem resistance. Experiments performed to confirm our findings included generating mutant isolates from the initial patient isolate, passaging the isolates for purity in drug-free medium, resulting in a reversible phenotype, and cloning the mutations to demonstrate the resistance conferred.
QOL-enhancing surgery for patients with HER2-positive metastatic breast cancer
Authors: Kai Masaya , Kubo Makoto , Kawaji Hitomi , Kurata Kanako , Mori Hitomi , Yamada Mai , Nakamura Masafumi
Published: September 2018

The role of the resection of primary tumour in stage IV breast cancer is unclear. Systemic therapy is recommended to prolong the survival and improve the quality of life (QOL). However, even if the systemic therapy is effective to control distant metastasis, sometimes the local lesion worsens, especially in the aggressive subtypes such as HER2-positive breast cancer. In uncontrollable tumours, the wound bed can bleed, weep and get infected, leading to dismal QOL. Our study describes two cases of patients with HER2-positive stage IV breast cancer who underwent palliative mastectomy which resulted in improvement of QOL. Local tumour control through palliative mastectomy can be beneficial for symptomatic aggressive patients with HER2-positive breast cancer to improve their QOL.
Phase II evaluation of anti-MAdCAM antibody PF-00547659 in the treatment of Crohn’s disease: report of the OPERA study
Authors: Sandborn William J , Lee Scott D , Tarabar Dino , Louis Edouard , Klopocka Maria , Klaus Jochen , Reinisch Walter , Hébuterne Xavier , Park Dong-Il , Schreiber Stefan , Nayak Satyaprakash , Ahmad Alaa , Banerjee Anindita , Brown Lisa S , Cataldi Fabio , Gorelick Kenneth J , Cheng John B , Hassan-Zahraee Mina , Clare Robert , D’Haens Geert R
Published: September 2018

Objective

This phase II, randomised, double-blind, placebo-controlled clinical trial was designed to evaluate the efficacy and safety of PF-00547659, a fully human monoclonal antibody that binds to human mucosal addressin cell adhesion molecule (MAdCAM) to selectively reduce lymphocyte homing to the intestinal tract, in patients with moderate-to-severe Crohn’s disease (CD).

Design

Eligible adults were aged 18–75 years, with active moderate-to-severe CD (Crohn’s Disease Activity Index (CDAI) 220–450), a history of failure or intolerance to antitumour necrosis factor and/or immunosuppressive agents, high-sensitivity C reactive protein >3.0 mg/L and ulcers on colonoscopy. Patients were randomised to PF-00547659 22.5 mg, 75 mg or 225 mg or placebo. The primary endpoint was CDAI 70-point decrease from baseline (CDAI-70) at week 8 or 12.

Results

In all, 265 patients were eligible for study entry. Although CDAI-70 response was not significantly different with placebo versus PF-00547659 treatment at weeks 8 or 12, remission rate was greater in patients with higher baseline C reactive protein (>5 mg/L vs >18.8 mg/L, respectively). Soluble MAdCAM decreased significantly from baseline to week 2 in a dose-related manner and remained low during the study in PF-00547659-treated patients. Circulating β
7
+ CD4+ central memory T-lymphocytes increased at weeks 8 and 12 with PF-00547659 treatment. No safety signal was seen.

Conclusions

Clinical endpoint differences between PF-00547659 and placebo did not reach statistical significance in patients with moderate-to-severe CD. PF-00547659 was pharmacologically active, as shown by a sustained dose-related decrease in soluble MAdCAM and a dose-related increase in circulating β
7
+ central memory T cells.

Trial registration number

NCT01276509
; Results.
Parkinson’s disease: evolution of cognitive impairment and CSF Aβ1–42 profiles in a prospective longitudinal study
Authors: Lerche Stefanie , Wurster Isabel , Röben Benjamin , Machetanz Gerrit , Zimmermann Milan , Bernhard Felix , Stransky Elke , Deuschle Christian , Schulte Claudia , Hansson Oskar , Zetterberg Henrik , Gasser Thomas , Berg Daniela , Maetzler Walter , Brockmann Kathrin
Published: September 2018

Objective

To evaluate the evolution of cognitive impairment in relation to cerebrospinal fluid (CSF) profiles of amyloid-β (Aβ), total-Tau and phosphorylated-Tau in Parkinson’s disease (PD).

Methods

Prospective, longitudinal, observational study up to 10 years with follow-up every 2  years. We assessed CSF profiles in 415 patients with sporadic PD (median age 66; 63% men) and 142 healthy controls (median age 62; 43% men).

Results

Patients with PD with low CSF Aβ1–42 levels at baseline were more often cognitively impaired than patients with intermediate and high Aβ1–42 levels. Sixty-seven per cent of the patients with low Aβ1–42 levels at baseline and normal cognition developed cognitive impairment during follow-up, compared with 41% and 37% of patients having intermediate and high CSF Aβ1–42 levels. Kaplan-Meier survival curves and Cox regression revealed that patients with low CSF Aβ1–42 levels at baseline developed cognitive impairment more frequently and earlier during follow-up.

Conclusion

We conclude that in patients with sporadic PD, low levels of Aβ1–42 are associated with a higher risk of developing cognitive impairment earlier in the disease process at least in a subgroup of patients.
The best interest standard and children: clarifying a concept and responding to its critics
Authors: Bester Johan Christiaan
Published: September 2018

This work clarifies the role of the best interest standard (BIS) as ethical principle in the medical care of children. It relates the BIS to the ethical framework of medical practice. The BIS is shown to be a general principle in medical ethics, providing grounding to prima facie obligations. The foundational BIS of Kopelman and Buchanan and Brock are reviewed and shown to be in agreement with the BIS here defended. Critics describe the BIS as being too demanding, narrow, opaque, not taking the family into account and not suitable as limiting principle. This work responds to these criticisms, showing that they do not stand up to scrutiny. They either do not apply to the BIS, only apply to misuses of the BIS or criticise a BIS that is not seriously defended in the literature.
Assessment of postoperative inflammatory markers and pain in cats after laparoscopy and miniceliotomy ovariectomy
Authors: da Conceição Maria Eduarda Bastos Andrade Moutinho , Uscategui Ricardo Andres Ramirez , Bertolo Paulo Henrique Leal , de Souza Damazio Campos , Rolemberg Daniele dos Santos , de Moraes Paola Castro , Teixeira Pedro Paulo Maia , Dias Luis Gustavo Gosuen Gonçalves
Published: September 2018

Videosurgery is increasingly used in veterinary medicine. Compared with open surgery, it has been shown to cause minimal pain and promote a more rapid recovery. There are various methods of assessing pain and postoperative inflammation in cats, although their particular behaviours may make these assessments difficult. The aim of this study was to compare levels of postoperative pain and inflammation after laparoscopic ovariectomy with an open minimally invasive technique. Twenty queens were randomly divided into two groups based on the method of haemostasis and surgical technique: (1) laparoscopic ovariectomy using a miniloop (miniloop group (MG)); and (2) minilaparotomy using a Snook hook (control group (CG)). Heart rate (HR), respiratory rate (RR), end tidal CO2(EtCO2) and body temperature were assessed using a multiparametric monitor during anaesthesia and surgery at defined surgical time points (preincision, left ovary manipulation, right ovary manipulation and skin suture). Blood samples (2 mL each) were collected from the jugular vein before surgery and 1, 12, 24, 48 and 72 hours, and 10 days, after endotracheal extubation for blood count analysis and to assess total protein and acute phase proteins (APP). EtCO2and RR were significantly higher in MG patients (P<0.001). HR was higher in the CG group for the duration of surgery (P=0.01). Temperature was significantly lower in MG patients (P<0.001). Pain assessment by dynamic interactive visual analogue scale showed no difference between groups or at specific moments of time within groups. Segmented neutrophil counts increased at 24 hours postoperatively and peaked at 48 and 72 hours in MG (P=0.01). The most important result among APPs was haptoglobin, which peaked at 72 hours in MG patients (P=0.001). Patients undergoing minilaparotomy and laparoscopy showed comparable postoperative pain. However, inflammatory changes such as APPs and neutrophil counts were increased in the laparoscopic group.
Earlier migration timing of salmonids: an adaptation to climate change or maladaptation to the fishery?
Authors: Morita Kentaro
Published: September 2018

Recent studies reporting shifts in the timing of salmonid migrations have suggested global warming to be a cause. However, the specific mechanisms underlining the evolution of earlier migration timing in salmonid fishes are unknown. In this paper, I present a hypothesis by which fishery-induced selection works to advance the timing of salmonid migration, given that the timings of migration and breeding are genetically controlled heritable traits. Although late-spawning salmon brood lines enter rivers after early-spawning brood lines, there is evidence that all brood lines arrive in coastal fishing grounds at similar times. As such, late-spawning brood lines would be fished for longer periods of time, with their increased harvest rate imposing directional selection on earlier-spawning brood lines. Thus, fisheries-induced evolution could favor the earlier timing of river entry to escape coastal fisheries. Should earlier migration timing not be an adaptation to global warming — should it be a maladaptation to fisheries-induced selection instead — then it will have a negative impact on the sustainability of salmonid resources.
The reproductive pattern of the Gerbilliscus cf. leucogaster (Rodentia: Muridae) from Namibia
Authors: Muteka Sachariah P. , Chimimba Christian T. , Bastos Armanda D. , Bennett Nigel C.
Published: September 2018

Very little is known about the reproductive biology of the Gerbilliscus cf. leucogaster (Peters, 1852) despite its wide distribution throughout the southern African subregion. Body mass, reproductive tract morphometrics, and gonadal histology were studied over 12 months in wild caught Gerbilliscus cf. leucogaster from the central part of Namibia to gain insights into the reproductive pattern of this species. The number of Graafian follicles and corpora lutea in 93 females increased at the end of the dry period (September) and throughout the wet months of the year (October–May) relative to that of the dry season (June–August). Pregnant and lactating females were recorded during the wet months of the year, with a peak observed during February. Testicular mass relative to body mass, testicular volume, and seminiferous tubule diameter in 64% of males increased significantly during the rainfall period (October–June). In addition, 8% of males exhibited little spermatogenesis and 28% showed no spermatogenesis or presence of sperm in the epididymis during the dry period (June–August). These findings suggest that the Gerbilliscus cf. leucogaster breeds predominantly during the rainfall period in Namibia when the food resources are more abundant.
Population genetic structure and assessment of allochronic divergence in the Macoun’s Arctic (Oeneis macounii) butterfly
Authors: Gradish A.E. , Keyghobadi N. , Sperling F.A.H. , Otis G.W.
Published: September 2018

Patterns in the genetic variation of species can be used to infer their specific demographic and evolutionary history and provide insight into the general mechanisms underlying population divergence and speciation. The Macoun’s Arctic (Oeneis macounii (W.H. Edwards, 1885); MA) butterfly occurs across Canada and parts of the northern United States in association with jack pine (Pinus banksiana Lamb.) and lodgepole pine (Pinus contorta Douglas ex Loudon). MA’s current distribution is highly fragmented, and the extent of reproductive isolation among allopatric populations is unknown. Furthermore, although MA is biennial, adults emerge every year in some populations. These populations presumably consist of two alternate-year cohorts, providing the opportunity for sympatric divergence via allochronic isolation. Using mitochondrial DNA (mtDNA) and amplified fragment length polymorphism (AFLP) markers, we analyzed MA’s genetic structure to determine the current and historical role of allopatric and allochronic isolation in MA population divergence. Both markers revealed high diversity and a low, but significant, degree of spatial structure and pattern of isolation by distance. Phylogeographic structure was generally absent, with low divergence among mtDNA haplotypes. MA likely exhibits low dispersal and gene flow among most allopatric populations; however, there was no evidence of differentiation resulting from allochronic isolation for sympatric cohorts.
Confluent hypergeometric systems associated with principal nilpotent p-tuples
Authors: Saito Mutsumi , Takeda Hiroyasu
Published: September 2018

Kimura and Takano showed that taking limits of regular elements of [Formula: see text] corresponds to the process of confluence of Aomoto–Gel’fand systems. We introduce a hypergeometric system associated with a principal nilpotent [Formula: see text]-tuple, and, by using the principal nilpotent [Formula: see text]-tuple, we directly deform a hypergeometric system of Gauss type into that of Airy type. Moreover, we explicitly describe the deformation.
Construction of solitary wave solutions to the nonlinear modified Kortewege-de Vries dynamical equation in unmagnetized plasma via mathematical methods
Authors: Iqbal Mujahid , seadawy Aly R. , Lu Dianchen
Published: September 2018

In this research, we consider the propagation of one-dimensional nonlinear behavior in a unmagnetized plasma. By using the reductive perturbation technique to formulate the nonlinear mathematic model which is modified Kortewege-de Vries (mKdV), we apply the extended form of two methods, which are extended auxiliary equation mapping and extended direct algebraic methods, to investigate the new families of electron-acoustic solitary wave solutions of mKdV. These new exact traveling and solitary wave solutions which represent the electrostatic potential for mKdV and also the graphical representation of electrostatic potential are shown with the aid of Mathematica.
Topological invariants for superconducting cosmic strings
Authors: Li Xinfei , Liu Xin
Published: September 2018

Superconducting cosmic strings (SCSs) have received revived interests recently. In this paper we treat closed SCSs as oriented knotted line defects, and concentrate on their topology by studying the Hopf topological invariant. This invariant is an Abelian Chern–Simons action, from which the HOMFLYPT knot polynomial can be constructed. It is shown that the two independent parameters of the polynomial correspond to the writhe and twist contributions, separately. This new method is topologically stronger than the traditional (self-)linking number method, which fails to detect essential topology of knots sometimes, shedding new light upon the study of physical intercommunications of superconducting cosmic strings as a complex system.
Damped harmonic oscillator and bosonic string theory through noncommutativity
Authors: De Andrade M. A. , Neves C.
Published: September 2018

Some features of noncommutativity are investigated in this work. A noncommutative (NC) versions for the 2D harmonic oscillator and scalar field theory are obtained via the Noncommutative Mapping and fourfold discussion are presented: first, the Lagrangian of the damped harmonic oscillator (DHO), which was an original explanation for the dissipative process presenting in the atomic nuclei collision, is reobtained through noncommutativity. Here, we show that the NC parameter plays the role of the viscous damping coefficient; second, the NC harmonic oscillator is mapped into the bosonic string theory in the light cone frame, which appears as a bosonic string theory attached to a D3-brane; third, we discuss the connection between DHO and bosonic string attached to a D3-brane; fourth, the NC scalar field is indicating into 2D-NC harmonic oscillator.