bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of Short-Term and Long-Term Wave Statistics by Time Domain Simulations Statistics
Authors: Hagen Øistein , Håøy Grue Ida , Birknes-Berg Jørn , Lian Gunnar , Bruserud Kjersti
Published: October 2017

In the design of new structures and assessment of existing structures, short- and long term statistical distributions of wave height, crest height and wave periods, as well as joint distributions, are important for structural integrity assessment. It is important to model the statistical distributions accurately to calculate wave design criteria and to assess fatigue life.

A detailed study of the wave statistics for an offshore location at the Norwegian Continental Shelf field is carried out. Extensive time domain simulations for the complete scatter diagram of possible sea states are carried out by a second order wave model. Time series of the surface elevation are generated for JONSWAP and Torsethaugen wave spectra, and for several wave spreading models. Statistics for individual wave heights, crest heights and wave periods are established. The simulated results for the short-term statistics are compared with existing short term models that are commonly used, viz. the Forristal, Næss and Rayleigh wave height distributions, and the Forristall 2nd order crest height distribution. Also, parameterized distributions for wave height and for crest height are fitted to the simulated data.

The long-term distributions F(H) and F(C) of all simulated individual wave heights H and crest heights C are determined by weighting the simulations with the long-term probability of occurrence of the sea state. Likewise, the long-term distributions F(Hmax) and F(Cmax) of the maximum simulated individual wave heights Hmax and crest heights Cmax in the sea states are determined.

The design criteria for return periods R = 1, 10, 100 and 10 000 years are determined from the appropriate quantile levels.

The effect of statistical uncertainty is investigated by comparing the confidence intervals for the estimated extreme values results as function of the number N of 3-hour time domain simulations per sea state for 10<N<500.
Sloshing and Swirling in Partially Loaded Prismatic Chamfered Tanks
Authors: Karuka Gustavo M. , Arai Makoto , Ando Hideyuki
Published: October 2017

In this study a sloshing experiment using a partially filled membrane tank model was carried out and compared with numerical simulation. The pressure was measured at 10 points and a load cell measured the longitudinal and transversal forces, under regular and irregular excitation. A 3D finite difference method based solver was used for the numerical simulation. When the prismatic tank length to breadth ratio is near 1, swirling, i.e., liquid free surface’s rotating motion in the tank might occur when the tank is excited near its natural frequency, especially for medium and low tank filling levels. According to the experimental and simulation data, the magnitude of the forces and impact pressures in this situation can be significant and therefore cannot be neglected. Tank designs might use different length to breadth ratios (Lt/Bt) depending on the ship size and number of tanks, so the problem is worth being investigated. The Lt/Bt and the occurrence of swirling was then investigated. The pressure distribution when the swirling occurs is then compared with the 1st mode sloshing pressure distribution, and considerations about the tank safety are inferred.
Structural Reliability Analysis Applied on Steel Ships for Rule Partial Safety Factors Calibration
Authors: Benhamou Alexis , Derbanne Quentin , de Lauzon Jérôme
Published: October 2017

Ultimate strength assessments in current IACS Common Structural Rules (CSR) are determined by a limited number of constant partial safety factors (PSF). These coefficients are inherited from the previous Common Structural Rules for Oil Tankers, and were determined using a structural reliability analysis (SRA) based on a limited number ship. The authors decided to lead a more comprehensive structural reliability analysis to propose and discuss a new set of rule formulations.

A literature review is carried out in order to determine an extensive database of virtual ships covering the whole range of existing ships with a few representative parameters. SRA is applied for ultimate strength assessment on this database. Uncertainties are modeled by a set of probability distributions applied to each characteristic quantity (still water bending moment, wave bending moment and capacity) and a Second Order Reliability Method (SORM) is used to target the ultimate capacity corresponding to a given failure probability for each ship.

A set of several PSF formulations are then derived from these results using both Working Stress Design (WSD) and Load and Resistance Factor Design (LRFD) approaches. These formulations are then discussed to get an optimum between simplicity and accuracy of the results.
Grounding Damage Estimate Through Acceleration Measurements
Authors: Haag Stan R. , Hoogeland Martijn G. , Vredeveldt Alex W.
Published: October 2017

Instantaneous insight into the structural damage sustained by a ship running aground, can be of great aid in the decision making following such a disaster. It should be possible to distil the extent of structural damage from acceleration measurement data of the entire vessel. Such measurements could possibly even be done using a simple smartphone.

This paper describes experimental research exploring the detection of plate rupture in a raking damage scenario by merely looking at acceleration measurement data. Drop tower experiments were performed, which reflect a realistic raking damage scenario and also aim to gain better understanding of both friction and failure in such a scenario.

In total four drop tests were performed. Ductile fracture occurred without precedence of necking. A calibration method for a failure criterion, using only one single strain-state, was successfully applied. Separate friction tests showed that static Coulomb friction seems to be a proper model to be applied for the energy dissipation through friction. Moreover, the transition to plate rupture can readily be detected from the experimental acceleration data.

When accurate calibration of both the failure and the friction is performed, it is envisaged that the extent of raking damage can indeed be derived through real time acceleration measurements on board of a vessel.
Application of Frequency Domain Methods for Response Based Analysis of Flexible Risers
Authors: Armstrong C. , Drobyshevski Y. , Chin C.
Published: October 2017

Response Based Analysis (RBA) is an advanced method for the prediction of long term distributions of critical responses in offshore floating systems. For complex non-linear systems such as flexible risers, RBA requires time domain simulations that form the core data to which probabilistic models are applied. Because RBA requires significantly larger amounts of data than traditional short term analysis approaches, running the required number of simulations in the time domain can quickly become unfeasible if the system’s physics being modelled are exceedingly complex. In addition, flexible risers are complex composite structures with highly dynamic, non-linear responses which further limit the feasibility of application of the RBA process to these systems.

As an alternative, frequency domain solvers, such as that used in the OrcaFlex software, are potential substitutes for portions of datasets due to their processing times being significantly faster than time domain solvers.

A comparison of extreme responses generated by frequency and time domain solvers was performed over the duration of two storms. An upper threshold limit for the frequency domain’s accuracy was found by comparing the differences of the two solver’s responses as the storm progressed; where the differences became too large the threshold limit was set. For environmental conditions smaller than this threshold, the frequency domain solver may provide a quicker method for predicting the riser responses. Conditions that exceed this threshold require full time domain analysis for accurate responses to be generated.

Limitations of the frequency domain solvers include their reduced ability to deal with non-linear mechanics such as bending/curvature responses. As a result, curvature component results from the frequency domain are limited in their direct usability, especially when exposed to more extreme metocean conditions and locations along the riser that are subject to larger curvature (generally where risers are connected to structures with greater stiffness).

Although these limitations exist, the frequency domain solver may still provide reasonable insight into metocean conditions that potentially cause extreme responses.

A method is proposed for the use of both frequency and time domain simulations in the flexible riser flowline RBA process. Screening, filtering and ‘stitching’ methods utilizing the speed of the frequency domain solver are presented in order to compensate for the time domain’s extensive computation times. The proposed method of stitching, when applied to an example storm history, required 39% of the processing time when using only the time domain solver.
Next Generation Hull-Platform “Noah-FPSO Hull” Based on Modular Design and Construction Concept
Authors: Tanaka Shigeru , Takano Kotaro
Published: October 2017

It is often said that every offshore oil field has its own environmental condition and oil property according to its geographical location. This means that it is very difficult to apply a specific standard design to any FPSO hull, which is usually preferred by many shipyards.

This fact often leads to serious trouble for FPSO hull construction in terms of cost and delivery time.

In order to cope with this problem, Mitsui Engineering and Shipbuilding Co., Ltd. (MES) developed a next generation offshore platform for FPSO, “Mitsui noah-FPSO Hull” (noah : New Offshore Adapted Hull), which consists of unique modular design and construction concept and simple hull form. Structural design is also modularized, i.e. common cross section and frame space, will facilitate to standardized topside module design. In fact, it can be constructed even in multi-shipyards as a consistent cross-platform.

MES has obtained Approval In Principle (AIP) for the noah-FPSO Hull design and concept from American Bureau of Shipping (ABS) and Bureau Veritas (BV).

In this paper, MES introduces these modular concept of the noah-FPSO Hull and its developed technical issues.
Nonlinear Random Wave Time Domain Analysis of Jack-Up Rigs Including Foundation
Authors: Chakrabarti Partha , Somasundaram Deepak Sankar , Chawan Abhijeet
Published: October 2017

A jack-up rig has to be designed for extreme storm conditions in its elevated mode during operations. Guidelines of ISO 19905-1 [1] and SNAME TR-5-5A [2] for site specific assessment of jack-up rigs explain in detail such analysis and assessment requirements. It is well known that for higher water depths and extreme environment, structural dynamics and spudcan-soil interaction plays a very significant role. The extreme storm response can be determined either by a two-stage deterministic storm analysis procedure using a quasi-static analysis that includes an inertial load set or by a more detailed fully integrated (random wave) dynamic analysis procedure that uses a stochastic analysis. More commonly, however, jack-up rigs are assessed using a two-stage deterministic wave model along with steady wind loads, since this is much simpler. In two-stage deterministic analysis, the first step is the determination of the inertial load set and structural analysis for all the environmental and gravity loads. To include the effects of the spudcan and soil foundation, an initial rotational stiffness or fixity is assumed that depends on the soil type and the preload. Assessment of the foundation is performed thereafter using the yield interaction approach. This is normally an iterative approach to arrive at the right fixity that satisfies the assessment.

The two-stage approach, although simpler could be conservative leading to adverse conclusions for the suitability of a jack-up at a site. As indicated, the other approach is the one-stage approach involving random time domain analysis which is normally not used and reported in the literature probably due to its complexity and difficulty.

The present paper describes random wave time domain analysis of a specific jack-up using a 3D model in 400 ft water depth using USFOS software [3]. This software has the spudcan-soil interaction integrated, to simulate the foundation behavior. In this one-stage analysis, the assessment for the foundation is performed through an iterative approach inside the software using yield and bounding surfaces. Extreme values of some of key responses are compared with traditional deterministic analysis. Benefits and limitations of random wave time domain analysis are explained and quantified. These benefits are sometimes so significant that one-stage analysis may lead to favorable conclusions where the conservative two-stage analysis approach had failed to show the adequacy of the rig. These observations and the overall methodology of analysis used here could be beneficial to any rig’s applicability at a specific site.
Yaw Galloping of a TLWP Platform Under High Speed Currents by Analytical Methods and its Comparison With Experimental Results
Authors: Lamas Francisco , Ramirez Miguel A. M. , Fernandes Antonio Carlos
Published: October 2017

Flow Induced Motions are always an important subject during both design and operational phases of an offshore platform life. These motions could significantly affect the performance of the platform, including its mooring and oil production systems.

These kind of analyses are performed using basically two different approaches: experimental tests with reduced models and, more recently, with Computational Fluid Dynamics (CFD) dynamic analysis. The main objective of this work is to present a new approach, based on an analytical methodology using static CFD analyses to estimate the response on yaw motions of a Tension Leg Wellhead Platform on one of the several types of motions that can be classified as flow-induced motions, known as galloping.

The first step is to review the equations that govern the yaw motions of an ocean platform when subjected to currents from different angles of attack.

The yaw moment coefficients will be obtained using CFD steady-state analysis, on which the yaw moments will be calculated for several angles of attack, placed around the central angle where the analysis is being carried out. Having the force coefficients plotted against the angle values, we can adjust a polynomial curve around each analysis point in order to evaluate the amplitude of the yaw motion using a limit cycle approach. Other properties of the system which are flow-dependent, such as damping and added mass, will also be estimated using CFD.

The last part of this work consists in comparing the analytical results with experimental results obtained at the LOC/COPPE-UFRJ laboratory facilities.
Hydrodynamics and Capture Efficiency of Plastic Cleanup Booms: Part I — Experiments and Dynamic Analysis
Authors: Brambini Roberto , Dommergues Bénédicte , Maral Hannah , Sainte-Rose Bruno
Published: October 2017

To reduce the threatening consequences of plastic pollution on marine ecosystems and global economy, The Ocean Cleanup (TOC) Foundation develops technologies to extract, prevent, and intercept plastic debris from coastal and oceanic environments. The core technology being optimized is the use of floating booms placed perpendicular to the main ocean plastic flow so it can concentrate plastic debris to a point where it can be extracted, shipped and processed in a cost-effective manner. To better understand the behavior of such a system in the vertical plane and to calibrate dynamic analysis models as well as Computational Fluid Dynamics (CFD) models, TOC conducted model tests of a portion of the boom at 1:5 scale. These tests were carried out in the Concept Basin at the Maritime Research Institute of the Netherlands (MARIN). The aim of this paper is to present those tests along with the assessment of the dynamics of the boom and the validation of a dynamic analysis model to predict the mooring loads on the system.
Reliability Analysis of Corroded Pipelines Under External Pressure
Authors: Teixeira A. P. , Palencia O. G. , Guedes Soares C.
Published: October 2017

This paper aims at assessing the reliability of pipelines with corrosion defects subjected to external pressure. Several design methods that explicitly account for the effect of corrosion damages on the collapse pressure of pipelines are considered. In particular, semi-empirical design equations derived from small-scale experiments and three-dimensional non-linear finite element analyses and design code methods currently used in practice are adopted. First, the design methods are analyzed and their predictions compared and then used to formulate the reliability problem of corroded pipelines subjected to external pressure. The reliability analysis adopts the state-of-the art stochastic models to characterize the uncertainty on the main parameters influencing the structural safety of corroded subsea pipelines. Parametric and sensitivity analyses are then performed for different levels of corrosion damages to identify the influence of the various parameters on the collapse probability of corroded pipelines under external pressure.
Driven Nonlinear Potential Flow With Wave Breaking at Shallow-Water Beaches
Authors: Gidel Floriane , Bokhove Onno , Kelmanson Mark
Published: October 2017

We introduce a new model of nonlinear dispersive waves generated by wavemakers in deep water, coupled to a shallow-water model with wave breaking, modelled as hydraulics bores, in the shore zone. Coupling of deep- and shallow-water models requires the formulation of an advanced space-time technology able to stably capture the free-surface dynamics. Our approach comprises the direct discretisation of the variational principle for the continuum modelling of potential-flow water-wave dynamics. Preservation of the variational structure in the discretisation ensures that important conservation properties of the original continuum system are inherited to a high degree by the discrete system. The nonlinear equations of motion resulting from the coupling of the potential-flow water-waves and the (breaking) shallow-water waves are solved in unison. By construction, this process results in a stable and robust numerical scheme that is well suited to demanding maritime applications.
Numerical Studies on Vortex-Induced Motions of a Semi-Submersible With Four Columns Based on IDDES Model
Authors: Hu Xiaofeng , Zhang Xinshu , You Yunxiang
Published: October 2017

The vortex-induced motions (VIM) of deep draft semi-submersible platforms have been challenging engineering issues because of its impact to the fatigue life of mooring and riser systems. This paper presents numerical studies on the vortex-induced motions (VIM) of a deep draft semi-submersible. Numerical simulations are performed by using an improved delayed detached eddy simulation (IDDES). VIM amplitudes for in-line (surge), transverse (sway) and yaw motions and hydrodynamic force coefficients are obtained for different current incidence angles. The sensitivity analyses on grids and time step sizes are carried out to ensure convergences of the computational results. Comparisons with experimental data demonstrate the capability of the present numerical model. It is observed that the transverse motions for 22.5° current incidence are larger than those for 0° and 45° current incidences. The mean drag force coefficients for these simulated current incidence angles tend to grow as the transverse motion amplitudes increase. In addition, parametric studies have also been performed to examine the effects of the column corner radius on VIM.
Structural Reliability Assessment of an Oil Tanker Accidentally Grounded in the Adriatic Sea
Authors: Ćorak Maro , Parunov Joško , Guedes Soares C.
Published: October 2017

The aim of the paper is to present a methodology for the assessment of the structural reliability of an oil tanker damaged in a hypothetical grounding accident in the Adriatic Sea. The grounding accident affects the ultimate hull girder capacity in the damaged region, the still water bending moment (SWBM) distribution along the vessel as well as the vertical wave bending moments (VWBM). The extent of the damage on the ship’s hull after a grounding accident depends on several parameters such as ship‘s speed, rock size, penetration depth, longitudinal and transversal location of stranding along the hull. These parameters are in the present study assumed as random variables, described by probability density functions. Based on defined statistical properties, random realizations of grounding parameters are simulated by Monte Carlo (MC) simulation. For each such random grounding scenario, the damage size is calculated by the surrogate model based on numerical grounding simulations. Residual ultimate strength and SWBM distribution are determined based on the size and location of the damage. VWBM is calculated for average sea state in the area with increased risk of grounding accident in the Adriatic Sea. Structural reliability analysis is employed to determine the safety index with respect to the ultimate hull girder failure for salvage period of 12 hours. As each grounding scenario results in different hull-girder reliability, histogram of safety indices is obtained representing new measures for the performance assessment of the damaged ship.
Fatigue Damage Estimation of Welded Joints Considering Mechanochemical Interaction
Authors: Liu Gang , Huang Yi , Zhang Qi , Li Zhiyuan , Chen Jingjie , Dong Leilei
Published: October 2017

The high stress region around weld joints accelerates corrosion and may induce non-uniform corrosion. In this study, the effect of loading on corrosion behavior of the steel in NaCl solution was investigated. The relationship between the corrosion rate and applied loading was deduced based on the electrochemical theory. Electrochemical experiments were carried out to investigate the interaction between loading and corrosion rate on Q235 steel. A butt weld joint of ship deck structure was selected as a case study. Time-dependent stress concentration factor of welded joint as a function of the corrosion deterioration was analyzed, and the iterative process of stress and corrosion degeneration of plate thickness was used to simulate the coupling effect based on results of the experiment. The hot spot stress approach was adopted to calculate the fatigue damage.
Interaction Between IL and CF VIV: On the Importance of Orbital Direction
Authors: Aronsen K. H. , Huang Z. Y. , Skaugset K. B. , Larsen C. M.
Published: October 2017

This paper discusses results from an experiment where forces on a rigid cylinder are measured during prescribed oscillations both in-line with and transverse to a constant flow. Two “figure of eight” oscillation patterns with identical shape but opposite orbital direction, relative to the flow, have been tested at a Reynolds number of 24000. Results show that the hydrodynamic force acting on the cylinder is significantly different for the two orbital directions. The force in phase with velocity, which represents the energy transfer between the fluid and the cylinder, has opposite sign and different magnitude for the two orbital directions. Flow visualization by particle image velocimetry (PIV) reveals that the two orbits leads to different vortex shedding modes. Hydrodynamic forces at multiples of the oscillation frequency, known as higher harmonics, are seen for both orbital directions. Comparison with pure in-line and pure transverse oscillations indicates that the higher harmonics are related to oscillations in in-line direction. A three-dimensional Large Eddy Simulation numerical simulation with equivalent experiment parameters has been conducted. It is very encouraging to see a good agreement between numerical results and observations with respect to global forces, vortex shedding modes and hydrodynamic co-efficients.
A Physics-Based Model for VIV Analysis
Authors: Konstantinidis Efstathios
Published: October 2017

A new hydrodynamic model is presented for analysis and prediction of the response of cylinders undergoing vortex-induced vibration transverse to a free stream. The model is based on the decomposition of the total force into reaction and excitation components respectively acting along the instantaneous relative velocity between the vibrating cylinder and the free stream, and normal to it. The reaction force is modeled via Morison’s equation to introduce fluid inertia due to added mass and fluid damping due to drag. It is verified that the resulting nonlinear model can reproduce the actual response when supplied with measured force coefficients. Model predictions with a set of constant fluid forcing parameters are found to be consistent with empirical formulas for the peak response as a function of the combined mass-damping.
Real-Time Hybrid Model Testing of a Top Tensioned Riser: A Numerical Case Study on Interface Time-Delays and Truncation Ratio
Authors: Sauder Thomas , Sørensen Asgeir J. , Larsen Kjell
Published: October 2017

This paper investigates the applicability of real-time hybrid model testing (ReaTHM testing) to the study of offshore systems in deep water. The focus is in particular on slender marine structures connecting floating structures to the seabed, and on how they could be truncated so that a model test setup at a reasonable scale could fit existing hydrodynamic laboratory infrastructures. In this context, ReaTHM testing consists in “substructuring” the slender structures in two parts. At the lower part of the water column, the first substructure is numerical, simulated using a nonlinear finite element method. On the upper part of the water column, the other substructure is physically modelled in an ocean basin. Both substructures interact in real-time through a set of sensors and actuators. This paper addresses through a case study the important issue of accuracy of ReaTHM testing, that is how the behavior of the substructured system varies from that of the emulated system. A top-tensioned riser in 1200m water depth is considered, with two truncation locations: 240m and 600m below the free surface. It is assumed that an artefact is introduced by the ReaTHM test setup, namely a time delay induced by e.g. the numerical calculations, or the actuation system. It is first shown how this artefact influences the accuracy of the setup, and then how the truncation ratio influences the tolerance of the ReaTHM test setup to such an artefact.
The production of phantom partials due to nonlinearities in the structural components of the piano
Authors: Rokni Eric , Neldner Lauren M. , Adkison Camille , Moore Thomas R.
Published: October 2017

Phantom partials are anomalous overtones in the spectrum of the piano sound that occur at sum and difference frequencies of the natural overtones of the string. Although they are commonly assumed to be produced by forced longitudinal waves in the string, analysis of the sound of a piano produced by mechanically vibrating the soundboard while all the strings are damped indicates that phantom partials can occur in the absence of string motion. The magnitude of the effect leads to the conclusion that nonlinearity in the non-string components may be responsible for some of the power in the phantom partials.
Rapid pathogen-specific phenotypic antibiotic susceptibility testing using digital LAMP quantification in clinical samples
Authors: Schoepp Nathan G. , Schlappi Travis S. , Curtis Matthew S. , Butkovich Slava S. , Miller Shelley , Humphries Romney M. , Ismagilov Rustem F.
Published: October 2017

Digital ultrafast loop-mediated isothermal amplification determines phenotypic antibiotic susceptibility of
Escherichia coli
in clinical urine samples in less than 30 min.
Neutralizing human monoclonal antibodies prevent Zika virus infection in macaques
Authors: Magnani Diogo M. , Rogers Thomas F. , Beutler Nathan , Ricciardi Michael J. , Bailey Varian K. , Gonzalez-Nieto Lucas , Briney Bryan , Sok Devin , Le Khoa , Strubel Alexander , Gutman Martin J. , Pedreño-Lopez Núria , Grubaugh Nathan D. , Silveira Cassia G. T. , Maxwell Helen S. , Domingues Aline , Martins Mauricio A. , Lee David E. , Okwuazi Erica E. , Jean Sherrie , Strobert Elizabeth A. , Chahroudi Ann , Silvestri Guido , Vanderford Thomas H. , Kallas Esper G. , Desrosiers Ronald C. , Bonaldo Myrna C. , Whitehead Stephen S. , Burton Dennis R. , Watkins David I.
Published: October 2017

Neutralizing antibodies prevent Zika infection in nonhuman primates.
Just say NO to leaky bone marrow vasculature in AML
Authors: Jonas Brian A.
Published: October 2017

Inhibition of nitric oxide (NO) production improved treatment response and normalized NO-mediated alterations in bone marrow vascular architecture and function in acute myeloid leukemia.
Bifidobacterium bifidum
Extracellular Sialidase Enhances Adhesion to the Mucosal Surface and Supports Carbohydrate Assimilation
Authors: Nishiyama Keita , Yamamoto Yuji , Sugiyama Makoto , Takaki Takashi , Urashima Tadasu , Fukiya Satoru , Yokota Atsushi , Okada Nobuhiko , Mukai Takao
Published: October 2017

Bifidobacterium
is a natural inhabitant of the human gastrointestinal (GI) tract. We studied the role of the extracellular sialidase (SiaBb2, 835 amino acids [aa]) from
Bifidobacterium bifidum
ATCC 15696 in mucosal surface adhesion and carbohydrate catabolism. Human milk oligosaccharides (HMOs) or porcine mucin oligosaccharides as the sole carbon source enhanced
B. bifidum
growth. This was impaired in a
B. bifidum
ATCC 15696 strain harboring a mutation in the
siabb2
gene. Mutant cells in early to late exponential growth phase also showed decreased adhesion to human epithelial cells and porcine mucin relative to the wild-type strain. These results indicate that SiaBb2 removes sialic acid from HMOs and mucin for metabolic purposes and may promote bifidobacterial adhesion to the mucosal surface. To further characterize SiaBb2-mediated bacterial adhesion, we examined the binding of His-tagged recombinant SiaBb2 peptide to colonic mucins and found that His-SiaBb2 as well as a conserved sialidase domain peptide (aa 187 to 553, His-Sia) bound to porcine mucin and murine colonic sections. A glycoarray assay revealed that His-Sia bound to the α2,6-linked but not to the α2,3-linked sialic acid on sialyloligosaccharide and blood type A antigen [GalNAcα1-3(Fucα1-2)Galβ] at the nonreducing termini of sugar chains. These results suggest that the sialidase domain of SiaBb2 is responsible for this interaction and that the protein recognizes two distinct carbohydrate structures. Thus, SiaBb2 may be involved in
Bifidobacterium
-mucosal surface interactions as well as in the assimilation of a variety of sialylated carbohydrates.

IMPORTANCE
Adhesion to the host mucosal surface and carbohydrate assimilation are important for bifidobacterium colonization and survival in the host gastrointestinal tract. In this study, we investigated the mechanistic basis for
B. bifidum
extracellular sialidase (SiaBb2)-mediated adhesion. SiaBb2 cleaved sialyl-human milk oligosaccharides and mucin glycans to produce oligosaccharides that supported
B. bifidum
growth. Moreover, SiaBb2 enhanced
B. bifidum
adhesion to mucosal surfaces via specific interactions with the α2,6 linkage of sialyloligosaccharide and blood type A antigen on mucin carbohydrates. These findings provide insight into the bifunctional role of SiaBb2 and the adhesion properties of
B. bifidum
strains.
Bilateral intracranial calcifications with bilateral facial cutaneous naevus: Sturge Weber syndrome
Authors: Saeed Muhammad Arif , Hilal Kiran , Chand Prem
Published: October 2017

Sturge Weber syndrome also known as mother spot disease belongs to a group of disorders called phakomatoses (neurocutaneous syndromes involving the central nervous and cutaneous systems). It is a congenital disorder of the vasculature of the meninges, brain, face and eyes. Clinically, it usually presents with seizures and other neurological complications, including mental retardation, contralateral hemiparesis and glaucoma. Its incidence is estimated at one case in 20 000–50 000 persons with equal frequency in boys and girls. We present a case of 18-months-old boy was brought by parents with history of seizures since birth resulting in fall 1 day back. Physical examination showed bilateral port-wine stain on face. CT head examination revealed bilateral intracranial calcification. This is a highly unusual presentation of Sturge Weber syndrome.
Hydrocele of the canal of Nuck presenting as a sausage-shaped mass
Authors: Ferreira Ana Filipa , Marques João Paulo , Falcão Francisco
Published: October 2017

A 23-year-old woman presented with a painless vulval swelling. On physical examination, a soft fluctuant sausage-shaped mass was found, measuring approximately 4 cm, extending from the right inguinal region to the labia majora. Ultrasound revealed a well-defined hypoechoic elongated mass, septated, extending from the superficial inguinal canal to labia majora. Sonographic findings were consistent with the diagnosis of a hydrocele of the canal of Nuck. Surgical exploration revealed an elongated cystic lesion with a total length of 13 cm, mucous component and internal septations. Histopathological examination of the surgical specimen confirmed the suspected diagnosis.
Eliminating implausible fisheries assessment models using fishers’ knowledge
Authors: Duplisea Daniel E.
Published: October 2017

Peer review of competing deepwater redfish (Sebastes mentella) assessment models revealed data inconsistencies where stock biomass decline shown by the survey in the 1990s was too rapid to be explained solely by reported catch. The models invoked different techniques to achieve fits, one by changing mortality at age and the other by survey weighting. The former fitted reported catch well, while the latter accepted a mismatch between reported and estimated catch. The assessments produced different estimates of historical stock size and future productivity. Interviews conducted with fishers of the stock suggested that catch was at least twice as high as the official record. In light of the fishers’ evidence, the model that invoked a large change in mortality with age to follow reported catch closely now appears less credible. This serves as a warning against introducing new biological mechanisms without credible justification. This is an example of how indicators derived from fisher’s knowledge, even if only from a small number of interviews, can be used to eliminate less plausible models.
Comparative genomic and plasmid analysis of beer-spoiling and non-beer-spoilingLactobacillus brevisisolates
Authors: Bergsveinson Jordyn , Ziola Barry
Published: October 2017

Beer-spoilage-related lactic acid bacteria (BSR LAB) belong to multiple genera and species; however, beer-spoilage capacity is isolate-specific and partially acquired via horizontal gene transfer within the brewing environment. Thus, the extent to which genus-, species-, or environment- (i.e., brewery-) level genetic variability influences beer-spoilage phenotype is unknown. Publicly available Lactobacillus brevis genomes were analyzed via BlAst Diagnostic Gene findEr (BADGE) for BSR genes and assessed for pangenomic relationships. Also analyzed were functional coding capacities of plasmids of LAB inhabiting extreme niche environments. Considerable genetic variation was observed in L. brevis isolated from clinical samples, whereas 16 candidate genes distinguish BSR and non-BSR L. brevis genomes. These genes are related to nutrient scavenging of gluconate or pentoses, mannose, and metabolism of pectin. BSR L. brevis isolates also have higher average nucleotide identity and stronger pangenome association with one another, though isolation source (i.e., specific brewery) also appears to influence the plasmid coding capacity of BSR LAB. Finally, it is shown that niche-specific adaptation and phenotype are plasmid-encoded for both BSR and non-BSR LAB. The ultimate combination of plasmid-encoded genes dictates the ability of L. brevis to survive in the most extreme beer environment, namely, gassed (i.e., pressurized) beer.
Omega-3 polyunsaturated fatty acid docosahexaenoic acid and its role in exhaustive-exercise-induced changes in female rat ovulatory cycle
Authors: Mostafa Abeer F. , Samir Shereen M. , Nagib R.M.
Published: October 2017

Exhaustive exercises can cause delayed menarche or menstrual cycle irregularities in females. Omega-3 polyunsaturated fatty acids (ω-3 PUFAs) are incorporated into a wide range of benefits in many physiological systems. Our work aimed to assess the role of ω-3 PUFA docosahexaenoic acid (DHA) on the deleterious effects of exhaustive exercise on the female reproductive system in rats. Virgin female rats were randomly divided into 4 groups (12 rats in each): control group, omega-3 group treated with DHA, exhaustive exercise group, and exhaustive exercised rats treated with DHA. Omega-3 was given orally to the rats once daily for 4 estrous cycles. Exhaustive exercises revealed lower levels in progesterone and gonadotropins together with histopathological decrease in number of growing follicles and corpora lutea. Moreover, the exercised rats showed low levels of ovarian antioxidants with high level of caspase-3 and plasma cortisol level that lead to disruption of hypothalamic–pituitary–gonadal axis. ω-3 PUFA DHA has beneficial effects on the number of newly growing follicles in both sedentary and exercised rats with decreasing the level of caspase-3 and increasing the antioxidant activity in ovaries. Exhaustive exercises can cause ovulatory problems in female rats that can be improved by ω-3 supplementation.
NH4Cl affects the expression of Wnt/β-catenin pathway in hepatocytes
Authors: Bai Lu , Li Jingjing , Liu Xiaorui , Li Shasha , Li Fulei , Chen Yanling , Yu Zujiang
Published: October 2017

We intended to explore whether NH4Cl influences the viability and regulates the expression of Wnt/β-catenin pathway in hepatocytes. The Chang liver cell line was used and cultured with different concentrations of NH4Cl (2.5, 5, 10, 20, 40, and 50 mmol/L) for 12, 24, and 48 h. The viability of hepatocytes was detected by MTT assay. The mRNA and protein expression level was analyzed with qRT–PCR and Western blotting, respectively. NH4Cl concentration significantly affects the viability of hepatocytes. With the increase of NH4Cl concentration, the viability of hepatocytes was decreased, accordingly. The mRNA and protein expression of Wnt1, β-catenin, and cyclin D was significantly increased after treatment with low concentrations of NH4Cl as compared with the control group, whereas their expression levels were decreased after treatment with high concentrations of NH4Cl. The mRNA and protein expression of Wnt1, β-catenin, and cyclin D was also significantly increased after treatment with NH4Cl for a short period as compared with the control group, whereas their expression levels were decreased after treatment with NH4Cl for a long period. In addition, we found NH4Cl treatment significantly reversed the results after RNA silencing of Wnt1 in hepatocytes. NH4Cl influences the viability of hepatocytes and affects the expression of Wnt/β-catenin pathway in hepatocytes.
The role of echolocation strategies for niche differentiation in bats
Authors: Denzinger Annette , Tschapka Marco , Schnitzler Hans-Ulrich
Published: October 2017

Guilds subdivide bat assemblages into basic structural units of species with similar patterns of habitat use and foraging modes, but do not explain mechanisms of niche differentiation. Bats have evolved four different echolocation strategies allowing the access to four different trophic niche spaces differing in niche dimensions. Bats foraging in open and edge spaces use the “aerial hawking or trawling strategy” and detect and localize prey by evaluating pulse–echo trains in which the prey echo is unmasked. The pulse–echo pairs deliver mainly positional information on the prey and only little information on its nature. Signals are highly variable and are adapted for detection and localization in open space and (or) edge space. In narrow space, bats identify prey by solving a pattern recognition task. Bats using the “flutter detecting strategy” evaluate glint pattern in prey echoes; bats using the “active gleaning strategy” evaluate the spectral–temporal pattern of the prey–clutter echo complex; and bats using the “passive gleaning strategy” evaluate the pattern of prey-generated cues to find food and use echolocation only for spatial orientation. The less variable signals of narrow space bats are adapted for pattern recognition. The diverse and species-rich tropical bat assemblage at Barro Colorado Island, Panama, is here used as an exemplar for assigning bats to guilds, and we discuss the role of echolocation and other adaptations for niche differentiation within guilds.
Structures and electronic properties of WmMon (m + n ≤ 7) clusters
Authors: Yu Zhicheng , Zhang Xiurong , Huo Peiying , Gao Kun
Published: October 2017

Geometric and electronic structures of W[Formula: see text]Mo[Formula: see text] (m + n [Formula: see text] 7) clusters have been systematically calculated by density functional theory (DFT) at the generalized gradient approximation (GGA) level for ground-state structures. Geometry optimization shows that clusters are almost bipyramid structures with m + n [Formula: see text] 4. E[Formula: see text] of clusters is mainly dominated by W atoms. And the substitution of atoms between W and Mo in Mo[Formula: see text] or W[Formula: see text] (n [Formula: see text] 7) clusters enhances the stability of the original clusters. The calculated IE shows that W[Formula: see text]Mo, W[Formula: see text]Mo2, W[Formula: see text]Mo3 and WMo[Formula: see text] are relatively more stable in the chemical reaction. In addition, the magnetism of clusters mainly comes from valance d orbitals.
Formation and breaching of two palaeolakes around Leh, Indus valley, during the late Quaternary
Authors: Mujtaba S. A. I. , Lal Ravish , Saini H. S. , Kumar Pawan , Pant N. C.
Published: October 2017

Of the several types of Quaternary deposits formed by glacial, alluvial and mass-wasting processes, with vast climatic and tectonic significance lake deposits stand out prominently in the Indus valley around the town of Leh. We studied a number of palaeolake deposits between the Zinchan–Indus confluence and Shey village and carried out optically stimulated luminescence (OSL) quartz dating of samples from critical sections. Our results indicate that, during the late Quaternary, the Indus River was dammed at least twice in the narrow gorge downstream of Spituk Gompa, forming a reservoir up to 35 km long in which 20–68 m thick sediments were deposited under fluvial and lacustrine environments. During the older phase, the Indus was blocked by debris of moraines/landslides in the narrow zone near the Zinchan–Indus confluence. The resulting lake existed between
c.
125 ± 11 and 87 ± 8 ka during marine isotopic stage (MIS) 5. No evidence of damming material is preserved. Present-day elevations of lake deposits suggest a possible extension of the lake up to Ranbirpura upstream. After the lake breach, the Indus River was again dammed near Phey village by the advancing alluvial fan of the Phyang River. This lake, extending up to Karu, formed at
c.
79 ± ka. The lake existed in this phase during
c.
72–49 ka, during cold-stage MIS-4. The lake was breached after
c.
46 ± 3 ka, however.
Annual cycle of temperature and snowmelt runoff in Satluj River Basin using
in situ
data
Authors: Tiwari Sarita , Kar Sarat C. , Bhatla R. , Bansal R.
Published: October 2017

Melting of snow and ice contributes a large amount of water to the streamflow in the Satluj River. During the winter season, there is low base flow in the river as compared to spring and summer. Temperature is one of the key factors which directly impacts snow and ice melting throughout the year. A substantial amount of snowmelt only occurs when all the snow in a pack reaches isothermal condition. It is therefore very important to know the duration of impact of temperature on snowmelt runoff. Since the Himalayas have very few stations observing hydrological as well as meteorological conditions, it is difficult to validate the snowmelt models and examine changes in small-scale features in river basins of the region. The present study examines the annual cycle and interannual variability of runoff in the Satluj Basin in the western Himalayas and documents the impact of temperature on snowmelt runoff of Satluj River using daily
in situ
data for the period 1982–2005. A multivariate regression model using precipitation and surface temperature has been developed to predict the discharge of Satluj River at a daily scale. It is seen that after every warm phase and cold phase of temperature, the impact persists for around one month and affects the snowmelt runoff during January, February and March at lower- and higher-elevation stations such as Bhakra and Kasol, respectively. The effect of a large fall and rise in temperature is noticed on snowmelt runoff measured at all the discharge stations, while a small temperature change does not affect the observed discharge at all the stations. The remote sensing and reanalysis data are consistent with
in situ
data in the basin, and there is no major change in peak month of discharge or the amplitude during two different periods at Rampur gauge station.
Supercloud
Authors: Shen Zhiming , Jia Qin , Sela Gur-Eyal , Song Weijia , Weatherspoon Hakim , Van Renesse Robbert
Published: October 2017

Infrastructure-as-a-Service (IaaS) cloud providers hide available interfaces for virtual machine (VM) placement and migration, CPU capping, memory ballooning, page sharing, and I/O throttling, limiting the ways in which applications can optimally configure resources or respond to dynamically shifting workloads. Given these interfaces, applications could migrate VMs in response to diurnal workloads or changing prices, adjust resources in response to load changes, and so on. This article proposes a new abstraction that we call a
Library Cloud
and that allows users to customize the diverse available cloud resources to best serve their applications.

We built a prototype of a Library Cloud that we call the
Supercloud
. The Supercloud encapsulates applications in a virtual cloud under users’ full control and can incorporate one or more availability zones within a cloud provider or across different providers. The Supercloud provides virtual machine, storage, and networking complete with a full set of management operations, allowing applications to optimize performance. In this article, we demonstrate various innovations enabled by the Library Cloud.
Canonizing Graphs of Bounded Tree Width in Logspace
Authors: Elberfeld Michael , Schweitzer Pascal
Published: October 2017

Graph canonization is the problem of computing a unique representative, a canon, from the isomorphism class of a given graph. This implies that two graphs are isomorphic exactly if their canons are equal. We show that graphs of bounded tree width can be canonized by logarithmic-space (logspace) algorithms. This implies that the isomorphism problem for graphs of bounded tree width can be decided in logspace. In the light of isomorphism for trees being hard for the complexity class logspace, this makes the ubiquitous class of graphs of bounded tree width one of the few classes of graphs for which the complexity of the isomorphism problem has been exactly determined.