bluuebunny/crossref_metadata_2025 huggingface dataset:
New Design Proposal for the TLP Type Offshore Wind Turbines
Authors: Nihei Yasunori , Matsuura Midori , Murai Motohiko , Iijima Kazuhiro , Ikoma Tomoki
Published: November 2013

In this paper, we will show a new proposal to design a Tension Leg Platform (TLP) type offshore wind turbines. Generally, TLPs are used in deepwater oil and gas development fields due to their favorable motion characteristics. In this field, they have high set up costs. An upper structure of 5MW wind turbine, however, is only 450tons at its total weight, which is much lighter than that of oil and gas platforms. Therefore the displacement and water plane area of the platform might be smaller. As a result, wave forces could decrease and it could lead initial tensions to be lower. This idea that leads to low set up costs was discussed in our previous paper. Principal particulars of TLP prototypes was proposed and a tank test with both waves and wind that used 1/100 scale models was examined in the previous paper. Capsizing could be observed based on the conventional design method. So we reason why and how this capsizing occured in this paper. Also we propose new design process and new TLP prototypes based on this process.
Damage and Failure in an X65 Steel Pipeline Caused by Trawl Gear Impact
Authors: Kristoffersen Martin , Børvik Tore , Langseth Magnus , Hopperstad Odd Sture , Ilstad Håvar , Levold Erik
Published: November 2013

Offshore pipelines subjected to accidental impact loads from trawl gear or anchors may experience large global deformations and large local strains, creating a complex stress and strain history. In this study experiments and numerical simulations have been carried out to investigate the impact of a pipeline which is subsequently hooked and released. Material and component tests have been performed to investigate the behaviour during impact, and to observe if/when fracture occurs. The pipes were first impacted in a pendulum accelerator at varying velocities before they were pulled straight in a tension machine. Fracture was found in the impacted area of all the pipes during straightening. Material tests were done to determine the characteristics of the X65 grade steel. Numerical simulations showed excellent compliance with the impact phase, while the load level in the stretching phase was a bit overestimated.
Development of a Calculation Method for Fuel Consumption of Ships in Actual Seas With Performance Evaluation
Authors: Tsujimoto Masaru , Kuroda Mariko , Sogihara Naoto
Published: November 2013

Greenhouse gas shall be reduced from shipping sector. For that purpose the regulation of EEDI (energy efficiency design index for new ships) and SEEMP (ship energy efficiency management plan) have been entry into force from 2013. In order to improve the energy efficiency in ship operation it is necessary to predict the fuel consumption accurately.

In actual seas the wave effect is the dominant component of the external forces. In particular it is well known the bow shape above water affects the added resistance in waves. To reflect the effect of the bow shape a method which takes into account the result of simplified tank tests is proposed here. Using the results of tank tests the effect of the bow shape above water can be evaluated with accuracy as well as with robustness.

Regarding to the fuel consumption it should be evaluated by combining the ship hydrodynamic performance with the engine characteristics. Especially the operating limits of the main engine, such as the torque limit and the over load protection, are affected to the ship hydrodynamic performance. In rough weather condition the revolution of the main engine will be reduced to be below the operating limits of the engine. This causes the large decrease of ship speed. To prevent the increase of fuel consumption, a control system by Fuel Index as an index of fuel injection has been applied to some ships. The calculation method for the fuel consumption by using Fuel Index is presented.

In this paper following contents are reported; 1) development of a calculation method for the added resistance due to waves combined with the simplified tank tests in short waves, 2) comparison of the calculation method with onboard measurement, 3) development of a calculation method for the fuel consumption considering the engine operating mode in actual seas and 4) comparison of the method with onboard measurement of a container ship.

From these investigations the availability of the present method is confirmed.
Improvement of Waterflood Oil Recovery by Wettability Alteration in Carbonate Reservoirs
Authors: Dakik Ahmad , Gupta Anuj
Published: November 2013

Most carbonate rocks tend to be oil wet, which negatively affects the recovery of hydrocarbons in waterflooding. Studies have shown that alteration of wettability through ion adjustment and surfactant addition can alter the wettability of the carbonate rock from oil wet to moderate or water wet. Through alteration of wettability recovery can be increased to higher values than what is expected when the reservoir is flooded with seawater. Adjustment in concentration of Mg2+, Ca2+, and SO42− ions and addition of surfactants have shown to be most effective in altering wettability. There has been limited research related to imbibition of carbonate rock samples representing reservoirs in brines containing solely Mg2+, Ca2+, or SO42− at atmospheric conditions. The effect of Non-Ionic and mixed Non-ionic with cationic surfactants on the alteration of wettability has been addresses in previous research.

In this study, Imbibition experiments were done on samples using brines of different ion components and concentrations to study the effect of salinity and ion composition on the recovery. Imbibition of lower salinity brines showed noticeably higher recovery than high salinity brines. The results are presented in dimensionless form of recovery and time for better comparison of wettability alteration and effect between samples. Lower salinity brines of Ca2+ and SO42− ion composition showed highest improvement in recovery. Surfactants were added during the imbibition measurement to view any further enhanced recovery at atmospheric conditions.
Docking and Undocking Considerations for Floatover Analyses and Operations
Authors: Duquesnay Jillian , Baldwin Jason , Rains James Wesley
Published: November 2013

An alternative to lifted installation of topsides by a derrick barge is installation of single, integrated offshore platform topsides by floatover method. Floatover installation reduces hook-up and commissioning, which results in overall schedule and cost savings. Numerous papers were written recently to describe many aspects of the floatover operations. Nature of the floatover is such that it requires detailed engineering analyses, numerical simulations, model testing, and planning to evaluate all phases of the operation [Ref 5], [Ref 6]. Proper analysis of floatover requires numerical simulations using time-domain methodology to evaluate the system non-linearities inherent in the floatover hardware, fendering, mooring lines. Normally, weight transfer stages are given a high profile however it is found that the docking and undocking stages are equally as important. These sensitive stages of the floatover operation occur when the barge is entering the jacket slot prior to the floatover and exiting the jacket slot afterwards. The operation is sensitive to the prevailing weather and the number of simulations to make sure the operations can be performed safely is significant. Results of the docking and undocking analyses usually determine the weather standby and thus workability. This paper will address the docking and undocking stages of floatover for a barge that does not have its own propulsion. The paper shall include a concurrent investigation on effects of weather criteria. Stiffness of the hardware, mating lines/cross lines, mooring lines and the effect they have on the system will be discussed.
MARINET: The Research Infrastructure Network Gaining International Support and Accelerating the Development of Marine Renewable Energy
Authors: Healy Mark , Alcorn Raymond , Lewis Tony
Published: November 2013

MARINET (Marine Renewables Infrastructure Network) is an EC-funded marine renewable energy infrastructure initiative which seeks to accelerate the development and commercial deployment of marine renewable energy technologies — wave, tidal & offshore-wind — by streamlining the testing process. World-class research centers and organizations are coming together in a network to offer periods of free-of-charge access to their world-class testing facilities and to develop a joint approach to testing standards, testing research and industry training & networking.

The growing network, with more than 30 full and associate partner research centers, has over 40 specialist marine research facilities covering all scales from laboratory to sea. It is spread across 11 EU countries and international partner countries such as Brazil, Taiwan, Canada and the US.

This paper outlines what MARINET is, what it has already achieved at the half-way point in the initiative, where it is going and who can benefit now and in the future.
Reliability Assessment of Fatigue Critical Welded Details in Wind Turbine Jacket Support Structures
Authors: Branner Kim , Toft Henrik Stensgaard , Haselbach Philipp , Natarajan Anand , Sørensen John D.
Published: November 2013

This paper describes a probabilistic approach to reliability assessment of fatigue critical welded details in jacket support structures for offshore wind turbines. The analysis of the jacket response to the operational loads is performed using Finite Element Method (FEM) simulations in SIMULIA Abaqus. Fatigue stress cycles are computed on the jacket members by applying tower top loads from an aeroelastic simulation with superimposed marine loads and in accordance to the IEC-61400-3 guidelines for operational conditions. The combined effect of the hydrodynamic loads and the rotor loads on the jacket structure is analyzed in a de-coupled scheme, but including the structural dynamics of the support structure.

The failure prediction of the welded joints, connecting the individual members of the support structure is based on SN-curves and Miners rule according to ISO 19902 and DNV-RP-C203/DNV-OS-J101. Probabilistic SN-curves and a stochastic model for Miners rule is used to estimate the reliability of selected critical welded details in the jacket structure taken into account the uncertainty in the fatigue stresses.
Dynamics of Entrapped Water in Large Diameter Turret Moonpools
Authors: de Vries Igor , Roux Yann , Naciri Mamoun , Bonnaffoux Guillaume
Published: November 2013

Development of Turret Mooring Systems (TMS) for harsh environment and large number of risers has led to a drastic increase of the size of the chaintable and consequently of the turret cylinder diameter. Furthermore, harsh environments usually require relatively deep drafts. As a consequence, the volume of entrapped water in large turrets increases to levels never designed for before. In some cases, the mass of the entrapped water can be comparable to the turret mass. Whilst this entrapped water does not exert any weight on the weathervaning system, its acceleration due to ship motions induces inertia loads which could affect the balance of loads. Estimation of these inertia loads is easily carried out assuming the entrapped water as frozen. However, to what extent is this assumption valid in view of the large amount of entrapped water involved and of the extreme ship motions expected in harsh environments? Should we expect sloshing of the entrapped water? In this paper, insights will be drawn from numerical techniques of diverse complexity. This will be preceded by a brief literature review on sloshing in moonpools. Practical analysis and design recommendations will be proposed. Operational aspects related to installation will be covered as well.
Safety Analysis at Conceptual Design of Marine Structures
Authors: Valdman Nikolai A.
Published: November 2013

The results of conceptual design of safety system elements for exploitation of offshore platforms, off-loading berths and terminals of liquid hydrocarbon in the Russian shelf seas are considered in the paper.

The methodical approaches used at substantiation of technical decisions on storage, offloading and liquid hydrocarbon transportation on objects of marine transport-technological systems (MTTS) are presented. The results of development of both a complex of measures on decrease of accident risk and using of safety criteria and factors are given.
A Method of Immersed Surface Capture for Broaching Application
Authors: Horel Boris , Guillerm Pierre-Emmanuel , Rousset Jean-Marc , Alessandrini Bertrand
Published: November 2013

The modeling of ship behavior in astern seas requires a large range of maneuverability and seakeeping knowledge since the understanding of the ship motions returns to solve a fluid structure interactions problem between waves and the ship hull. The broaching phenomenon is known as an abrupt change in motion in the horizontal plane, resulting in a loss of ship’s heading. It is characterized by a sudden divergence of yaw. Thus, there is a transfer of the kinetic energy on the roll axis that increases the risk of ship capsize. In the aim of modeling this phenomenon, the developed model uses the capture of the intersection between the ship hull and the free surface. Thus, we can overcome the hydrostatic stiffness matrix and integrate directly the hydrostatic pressure on the immersed surface. This method has the advantage of taking into account non-linearities of the wave profile into the calculation of the immersed surface, directly by performing a remodeling of the facets near the free surface. In the literature, three main factors are likely to affect the stability: the loading of the vessel, the presence of external disturbance torques and inadequate conditions of navigation, as is the case when a ship is caught in a storm. The first two factors are taken into account in the study of static stability, while the third factor is considered in the study of the instantaneous stability. Hydrostatic behavior of a ship is interesting when one wants to know her intact stability limits in calm seas. However, in the study of the ship behavior in following seas, the ship is no longer in usual conditions of navigation, but in unsuitable conditions requiring the study of the instantaneous stability. In the model formulation, the dynamic torsor comes from the general non-linear maneuverability equations and the time advance is solved by a 4th order Runge Kutta scheme with a constant time step. The torsor of the total applied mechanical action on the ship hull is expressed as the superposition of six torsors (gravity, hydrostatic, Froude Krylov, radiation, hydrodynamics and maneuverability) expressed in the center of gravity of the ship. Thus, we obtain a strong coupling between the maneuverability and seakeeping equations. Validation cases will be conducted and presented. The improvement of the model will require the implementation of test campaigns that will be specific for the study of ship behavior in astern seas. Validation of the model will help to define new stability criteria for ships in wave.
Analysis of Experimental Results on the Space-Time Evolution of Wave Groups in Crossing Seas
Authors: Santoro Anita , Guedes Soares C. , Arena Felice
Published: November 2013

The space-time evolution of high wave groups in crossing seas is studied. Profiles are calculated by applying Quasideterminism theory of Boccotti to laboratory data, given that a high crest takes place in a fixed point in the basin. It is observed that the high waves group is given by the superposition of two wave groups, associated one to the low-frequency component of the frequency spectrum and the other to the high-frequency one. It is shown how in crossing seas, the change in direction of one system affects the evolution of the related group, without any influence on the evolution of the other one. Different locations of high crest occurrence have been considered in order to study the effect of the change in spectrum on the deterministic profiles. It is shown that in crossing seas the profile at each location reflects the spectrum related to that specific point.
Unsteady Hydrofoils: Theoretical and Computational Analysis
Authors: Valentine Daniel T.
Published: November 2013

In this paper the computational problem examined is the impulsive start of a two-dimensional flat-plate hydrofoil at a fixed angle of attack. The method applied is an equally-spaced lumped-vortex panel method. The results from a lumped-vortex wake model and a shed-vortex sheet wake model are reported. Comparisons with the linear theory of Wagner (1925), the theoretical results associated with the single lumped-vortex wake model and the full wake model are presented. In addition, it is shown that the computational predictions are consistent with results reported by Katz and Plotkin (2001); they applied a distribution of vortices to model the wake. In the present paper the importance of resolving the chordwise pressure distribution in unsteady hydrofoil problems is elucidated. New predictions of both the evolution of lift and induced drag are reported for the instantaneously started flat plate. The computational predictions are compared with theorecticalpredictions also discussed in this paper.
Assessment of Fatigue Reliability for Jacket-Type Offshore Platforms Considering Dynamic Behavior
Authors: Khedmati Mohammad Reza , Rigo Philippe , Amrane Amirouche , Nazari Masoud
Published: November 2013

In order to traditionally investigate the strength of marine structures, the structure is subjected to a maximum static load. However, the marine structures are usually suffering environmental forces varying with time. Wave forces are the most important time dependent loading that causes fatigue in structural elements and joints. In this paper different methods base on S-N curve and linear elastic failure mechanics are presented. The governing equations and theories that are used in each method are expressed and the application of each method will be discussed.

The two main methods of deterministic analyses are: stress-based approach (S-N curve approach) and linear elastic fracture mechanics (LEFM) approaches. These approaches are applicable to different analyzing strategies, ie the first approach is used for cases in which general form of fatigue is dominant, but the latter involves the calculations of reliability as functions of crack geometry and its boundary conditions.

The SPD12C jacket platform in South Pars Oil Field is also modeled as a case study and the results of fatigue reliability analysis are presented.

In this paper a comprehensive method is presented to accurately predict the reliability of offshore platforms. This method is based on S-N curve and the results are compared with the fatigue life of joints.

Due to nonlinear interaction of soil and piles and the other affecting parameters such as flexibility of joints, non Gaussian procedure of loading, and nonlinearity of reaction force, the precise analyzing of stress levels will be impossible and a complex numerical analysis could only give limited information about the statistical properties of stress. In order to perform the fatigue analysis and predicting the cycles of stress SACS was used which is known as a powerful software in designing and analyzing offshore structures [1].

In this paper the whole structure was modeled subjected to different forces such as wave and sea currents. The effects of parameters such as marine growth and interaction of soil and piles are also included. The latter is shown to have a significant effect on determination of fatigue life of the platform.
Towards a Different View on Ship Design: The Development of Ships Observed Through a Social-Technological Perspective
Authors: van Bruinessen Ties , Hopman Hans , Smulders Frido
Published: November 2013

Designing large, innovative ships is a complex assignment and an interesting one for every company: Ship designers are capable of supporting the client’s requests and deliver a design quicker than any other related industry involved in the design of complex objects. However, at the same time it is felt that the industry could improve their innovative output by applying a more focused method to design these innovative and complex ships. Existing methods either mitigate the complex relations between systems of a ship, or concentrate on the design of a single object.

The design models evaluated in this paper, amongst others, the design spiral and system engineering, do not describe these important aspects of the ship-design cycle: To evolve beyond the current innovations, current design models do not suffice. The model presented in this paper takes the complex relations through different levels of decomposition into account and presents the possibility to track and support change during the design process. In future research, the model will be applied and developed further towards approaches and tools to support innovative design.
Stability Analysis of Breakwater Under Seepage Flow Using DDA
Authors: Chen Guangqi , Zheng Lu , Zhang Yingbin , Dong Simeng , Kasugai Yasuo , Kawakami Tsukasa
Published: November 2013

In order to explain the mechanism of breakwater failure destroyed by the massive tsunami triggered by the 2011 off the Pacific coast of Tohoku Earthquake, a failure mode is presented from the view of geotechnical engineering by considering the seepage force rather than the failure modes by using the existing failure mechanisms released in Coastal Engineering. It is proposed that a pseudo-steady state flow condition inside of the rubble mound can be created by high hydraulic head difference, which becomes possible due to the behaviour of the long period of tsunami wave. At first, a piping initiated local failure model is proposed and the phenomenon of piping initiated failure by laboratory model experiments is re-enacted. Also, the piping-initiated local failure of a breakwater is re-enacted by DDA simulation. And then, DDA is applied to the stability analysis of breakwater under seepage flow with new proposed displacement based failure criteria which can consider both global and local failure. A relationship between the height of a tsunami with the safety factor of a breakwater has been obtained. The results have been validated by both the laboratory model experiments and comparison with simplified Bishop Method.
Effect of Skirts on the Lateral Capacity of Mudmats in Soft Clay
Authors: Cao Jianchun , Yang Luo
Published: November 2013

This paper presents the development of a three-Dimensional Finite Element Analysis (3D FEA) model using Finite Element Code PLAXIS 3D to investigate the skirt’s effect on the lateral capacity of a mudmat in soft clay. It is found that, for a skirted mudmat, 1) the stiffness of skirts had an influence on the mobilization of its ultimate lateral capacity; 2) the required lateral displacement to mobilize the ultimate lateral capacity was about 1% of its width; 3) the lateral capacity is proportional to skirt depth under a soft clay condition with a linearly increasing strength; 4) the ultimate lateral capacity can also be increased by adding internal skirts, but the rate of increase becomes less prominent with the increase of internal skirt number; 5) an empirical formula in ISO19901-4 [5] was confirmed to conservatively estimate the lateral capacity of a skirted mudmat. Moreover, the influence of skirt on the involved soil mass was discussed.
Suppressing Full-Scale Riser VIV With the VT Suppressor
Authors: King Roger , Brown Andrew , Braaten Henning , Russo Massimiliano , Baarholm Rolf , Lie Halvor
Published: November 2013

The paper reports on recent full scale experimental tests with The Ventilated Trouser (VT), a novel device for VIV suppression of cylindrical structures exposed to external fluid flow. The VT suppressor is a loose fitting sleeve in the form of a light flexible net with integral bobbins in a special arrangement (Fig 1). It is omni-directional, rugged, and made from materials compatible with the offshore environment.

The tests reported here, originated in an invitation from Statoil to test the VT on a slick riser section. They were undertaken at Marintek, Norway, with a 0.53m diameter riser in current velocities up to 2.3m/s, equivalent to post-Critical Reynolds Numbers of up to 1.2 × 106.

The VT suppressed the maximum VIV amplitude of the slick joint by over 90%. This was consistent with the suppression performance of the VT from previous tests with model risers varying in size from 0.1m diameter to 0.3m diameter.

The test results suggest the VT is a candidate suppressor fully capable of competing with conventional suppression devices.
Verification of Gamma Knife extend system based fractionated treatment planning using EBT2 film
Authors: Natanasabapathi Gopishankar , Bisht Raj Kishor
Published: November 2013

Purpose:

This paper presents EBT2 film verification of fractionated treatment planning with the Gamma Knife (GK) extend system, a relocatable frame system for multiple‐fraction or serial multiple‐session radiosurgery.

Methods:

A human head shaped phantom simulated the verification process for fractionated Gamma Knife treatment. Phantom preparation for Extend Frame based treatment planning involved creating a dental impression, fitting the phantom to the frame system, and acquiring a stereotactic computed tomography (CT) scan. A CT scan (Siemens, Emotion 6) of the phantom was obtained with following parameters: Tube voltage—110 kV, tube current—280 mA, pixel size—0.5 × 0.5 and 1 mm slice thickness. A treatment plan with two 8 mm collimator shots and three sectors blocking in each shot was made. Dose prescription of 4 Gy at 100% was delivered for the first fraction out of the two fractions planned. Gafchromic EBT2 film (ISP Wayne, NJ) was used as 2D verification dosimeter in this process. Films were cut and placed inside the film insert of the phantom for treatment dose delivery. Meanwhile a set of films from the same batch were exposed from 0 to 12 Gy doses for calibration purposes. An EPSON (Expression 10000 XL) scanner was used for scanning the exposed films in transparency mode. Scanned films were analyzed with inhouse written MATLAB codes.

Results:

Gamma index analysis of film measurement in comparison with TPS calculated dose resulted in high pass rates >90% for tolerance criteria of 1%/1 mm. The isodose overlay and linear dose profiles of film measured and computed dose distribution on sagittal and coronal plane were in close agreement.

Conclusions:

Through this study, the authors propose treatment verification QA method for Extend frame based fractionated Gamma Knife radiosurgery using EBT2 film.
The ζ Isoform of Diacylglycerol Kinase Plays a Predominant Role in Regulatory T Cell Development and TCR-Mediated Ras Signaling
Authors: Joshi Rohan P. , Schmidt Amanda M. , Das Jayajit , Pytel Dariusz , Riese Matthew J. , Lester Melissa , Diehl J. Alan , Behrens Edward M. , Kambayashi Taku , Koretzky Gary A.
Published: November 2013

Despite its relatively low abundance, DGKζ exerts a major inhibitory effect on T cell receptor signaling.
In Vitro
Pharmacodynamics of Polymyxin B and Tigecycline Alone and in Combination against Carbapenem-Resistant Acinetobacter baumannii
Authors: Hagihara Mao , Housman Seth T. , Nicolau David P. , Kuti Joseph L.
Published: November 2013

Carbapenem-resistant
Acinetobacter baumannii
is increasing in prevalence. Polymyxin B and tigecycline are among the most active antibiotics used against this pathogen
in vitro
. Past
in vitro
studies, however, neglected the importance of simulating exposures observed in humans to determine their antibacterial effects. In this study, four carbapenem-resistant
A. baumannii
isolates were evaluated using an
in vitro
pharmacodynamic model. Free-drug exposures using 1 mg/kg of body weight of polymyxin B every 12 h (q12h), 100 and 200 mg tigecycline q12h, and the combination of these regimens were simulated. The microbiological responses to these treatments were measured by the change in log
10
CFU/ml over 24 h and the area under the bacterial killing and regrowth curve (AUBC). Resistance was assessed by a population analysis profile (PAP) conducted after 24 h of treatment. Polymyxin B achieved a reduction on the order of −2.05 ± 0.68 log
10
CFU/ml against these
A. baumannii
isolates, while all isolates grew to control levels with tigecycline monotherapy. Combination therapy with polymyxin B plus 200 mg tigecycline q12h achieved a greater reduction in bacterial density than did therapy with polymyxin B alone (−3.31 ± 0.71 versus −2.05 ± 0.68 log
10
CFU/ml,
P
< 0.001) but not significantly different than combination therapy with 100 mg tigecycline q12h (−2.45 ± 1.00 log
10
CFU/ml,
P
= 0.370). Likewise, combination therapy with polymyxin B plus 200 mg tigecycline q12h significantly reduced the AUBC compared to that with polymyxin B alone (62.8 ± 8.9 versus 79.4 ± 10.5 log
10
CFU/ml,
P
< 0.05). No changes in the PAP from baseline were observed for either antibiotic alone. In this study, combination therapy with simulated exposures of polymyxin B and tigecycline at an aggressive dose of 200 mg q12h produced synergistic or additive effects on humans against these multidrug-resistant
A. baumannii
strains.
Severe Sepsis Facilitates Intestinal Colonization by Extended-Spectrum-β-Lactamase-Producing Klebsiella pneumoniae and Transfer of the SHV-18 Resistance Gene to Escherichia coli during Antimicrobial Treatment
Authors: Guan Jun , Liu Shaoze , Lin Zhaofen , Li Wenfang , Liu Xuefeng , Chen Dechang
Published: November 2013

Infections caused by multidrug-resistant pathogens are frequent and life threatening in critically ill patients. To investigate whether severe sepsis affects gut colonization by resistant pathogens and genetic exchange between opportunistic pathogens, we tested the intestinal-colonization ability of an extended-spectrum beta-lactamase-producing
Klebsiella pneumoniae
strain carrying the SHV-18 resistance gene and the transfer ability of the resistance gene to endogenous
Escherichia coli
under ceftriaxone treatment in rats with burn injury only or severe sepsis induced by burns plus endotoxin exposure. Without ceftriaxone treatment, the
K. pneumoniae
strain colonized the intestine in both septic and burned rats for a short time, with clearance occurring earlier in burn-only rats but never in sham burn rats. In both burned and septic rats, the colonization level of the challenge strain dropped at the beginning and then later increased during ceftriaxone treatment, after which it declined gradually. This pattern coincided with the change in resistance of
K. pneumoniae
to ceftriaxone during and after ceftriaxone treatment. Compared with burn-only injury, severe sepsis had a more significant effect on the change in antimicrobial resistance to ceftriaxone. Only in septic rats was the resistance gene successfully transferred from the challenge strain to endogenous
E. coli
during ceftriaxone treatment; the gene persisted for at least 4 weeks after ceftriaxone treatment. We concluded that severe sepsis can facilitate intestinal colonization by an exogenous resistant pathogen and the transfer of the resistance gene to a potential endogenous pathogen during antimicrobial treatment.
Metronidazole and Hydroxymetronidazole Central Nervous System Distribution: 1. Microdialysis Assessment of Brain Extracellular Fluid Concentrations in Patients with Acute Brain Injury
Authors: Frasca Denis , Dahyot-Fizelier Claire , Adier Christophe , Mimoz Olivier , Debaene Bertrand , Couet William , Marchand Sandrine
Published: November 2013

The distribution of metronidazole in the central nervous system has only been described based on cerebrospinal fluid data. However, extracellular fluid (ECF) concentrations may better predict its antimicrobial effect and/or side effects. We sought to explore by microdialysis brain ECF metronidazole distribution in patients with acute brain injury. Four brain-injured patients monitored by cerebral microdialysis received 500 mg of metronidazole over 0.5 h every 8 h. Brain dialysates and blood samples were collected at steady state over 8 h. Probe recoveries were evaluated by
in vivo
retrodialysis in each patient for metronidazole. Metronidazole and OH-metronidazole were assayed by high-pressure liquid chromatography, and a noncompartmental pharmacokinetic analysis was performed. Probe recovery was equal to 78.8% ± 1.3% for metronidazole in patients. Unbound brain metronidazole concentration-time curves were delayed compared to unbound plasma concentration-time curves but with a mean metronidazole unbound brain/plasma AUC
0–τ
ratio equal to 102% ± 19% (ranging from 87 to 124%). The unbound plasma concentration-time profiles for OH-metronidazole were flat, with mean average steady-state concentrations equal to 4.0 ± 0.7 μg ml
−1
. This microdialysis study describes the steady-state brain distribution of metronidazole in patients and confirms its extensive distribution.
A Novel Staphylococcal Cassette Chromosomal Element, SCC
fusC
, Carrying
fusC
and
speG
in Fusidic Acid-Resistant Methicillin-Resistant Staphylococcus aureus
Authors: Lin Yu-Tzu , Tsai Jui-Chang , Chen Hsiao-Jan , Hung Wei-Chun , Hsueh Po-Ren , Teng Lee-Jene
Published: November 2013

A high prevalence of
fusC
(16/46, 59%) was found in fusidic acid-resistant methicillin-resistant
Staphylococcus aureus
isolates collected from 2008 to 2010. Nucleotide sequencing of
fusC
and flanking regions revealed a novel staphylococcal cassette chromosome (SCC) structure, SCC
fusC
, which was integrated into
rlmH
and located upstream from SCC
mec
. The SCC
fusC
element contained
speG
, which may contribute to the polyamine resistance.
Clinical and genetic aspects of hypophosphatasia in Japanese patients
Authors: Taketani Takeshi , Onigata Kazumichi , Kobayashi Hironori , Mushimoto Yuichi , Fukuda Seiji , Yamaguchi Seiji
Published: November 2013

Objective

We examined the clinical and genetic features of hypophosphatasia (HPP) in Japanese patients. HPP is a rare metabolic bone disorder of bone mineralisation caused by mutations in the liver/bone/kidney alkaline phosphatase (ALPL) gene, which encodes tissue-non-specific alkaline phosphatase isoenzyme. 

Methods

We retrospectively investigate the incidence and clinical features of 52 patients with paediatric HPP who were born between 1999 and 2010. Mutations of the ALPL gene were analysed in 31 patients.

Results

The annual incidence of perinatal lethal HPP (PLH) was estimated to be 2–3/1 000 000 births. The most frequent clinical type was PLH followed by prenatal benign. In addition to bone symptoms, cerebral manifestations were frequently observed including convulsion, mental retardation, deafness and short stature with growth hormone deficiency. Respiratory failure was the most significant predictor of a poor prognosis for PLH. The first and second most frequent mutations in the ALPL gene were c.1559delT and c.T979C (p.F327L), respectively. The c.1559delT homozygous mutation was lethal with respiratory failure. Patients with the p.F327L compound heterozygous mutation had the different non-lethal type with short stature and a gradual improvement in ALP level and bone mineralisation.

Conclusions

The most frequent clinical type was the PLH type with prognosis related to respiratory failure, biochemical/radiological changes and ALPL mutations. Cerebral manifestations frequently occurred. Genotype–phenotype correlations were associated with specific outcomes in the PLH type, whereas different clinical features were associated with the same genotype in the non-lethal type.
Ten days of simulated live high:train low altitude training increases Hbmass in elite water polo players
Authors: Garvican-Lewis Laura A , Clark Sally A , Polglaze Ted , McFadden Greg , Gore Christopher J
Published: November 2013

Objectives

Water polo requires high aerobic power to meet the demands of match play. Live high:train low (LHTL) may enhance aerobic capacity at sea level. Before the Olympics, the Australian women's water polo team utilised LHTL in an attempt to enhance aerobic fitness.

Methods

Over 6 months, 11 players completed three normobaric LHTL exposures (block 1:11 days at 3000 m; block 2+3:9 days at 2500 m, 11 days normoxia, 10 days at 2800 m). Haemoglobin mass (Hbmass) was measured through carbon monoxide-rebreathing. Before each block, the relationship between Hbmass and water polo-specific aerobic fitness was investigated using the Multistage Shuttle Swim Test (MSST). Effect size statistics were adopted with likely, highly likely and almost certainly results being >75%, >95%, >99%, respectively. A Pearson product moment correlation was used to characterise the association between pooled data of Hbmass and MSST.

Results

Hbmass (mean±SD, pre 721±66 g) likely increased after block 1 and almost certainly after block 2+3 (% change; 90% confidence limits: block 1: 3.7%; 1.3–6.2%, block 2+3: 4.5%; 3.8–5.1%) and the net effect was almost certainly higher after block 2+3 than before block 1 (pre) by 8.5%; 7.3–9.7%. There was a very large correlation between Hbmass (g/kg) and MSST score (r=0.73).

Conclusions

LHTL exposures of <2 weeks induced approximately 4% increase in Hbmass of water polo players. Extra Hbmass may increase aerobic power, but since match performance is nuanced by many factors it is impossible to ascertain whether the increased Hbmass contributed to Australia's Bronze medal.
Wellness, fatigue and physical performance acclimatisation to a 2-week soccer camp at 3600 m (ISA3600)
Authors: Buchheit Martin , Simpson Ben M , Garvican-Lewis Laura A , Hammond Kristal , Kley Marlen , Schmidt Walter F , Aughey Robert J , Soria Rudy , Sargent Charli , Roach Gregory D , Claros Jesus C Jimenez , Wachsmuth Nadine , Gore Christopher J , Bourdon Pitre C
Published: November 2013

Objectives

To examine the time course of wellness, fatigue and performance during an altitude training camp (La Paz, 3600 m) in two groups of either sea-level (Australian) or altitude (Bolivian) native young soccer players.

Methods

Wellness and fatigue were assessed using questionnaires and resting heart rate (HR) and HR variability. Physical performance was assessed using HR responses to a submaximal run, a Yo-Yo Intermittent recovery test level 1 (Yo-YoIR1) and a 20 m sprint. Most measures were performed daily, with the exception of Yo-YoIR1 and 20 m sprints, which were performed near sea level and on days 3 and 10 at altitude.

Results

Compared with near sea level, Australians had moderate-to-large impairments in wellness and Yo-YoIR1 relative to the Bolivians on arrival at altitude. The acclimatisation of most measures to altitude was substantially slower in Australians than Bolivians, with only Bolivians reaching near sea-level baseline high-intensity running by the end of the camp. Both teams had moderately impaired 20 m sprinting at the end of the camp. Exercise HR had large associations (r>0.5–0.7) with changes in Yo-YoIR1 in both groups.

Conclusions

Despite partial physiological and perceptual acclimatisation, 2 weeks is insufficient for restoration of physical performance in young sea-level native soccer players. Because of the possible decrement in 20 m sprint time, a greater emphasis on speed training may be required during and after altitude training. The specific time course of restoration for each variable suggests that they measure different aspects of acclimatisation to 3600 m; they should therefore be used in combination to assess adaptation to altitude.
Altitude training and haemoglobin mass from the optimised carbon monoxide rebreathing method determined by a meta-analysis
Authors: Gore Christopher J , Sharpe Ken , Garvican-Lewis Laura A , Saunders Philo U , Humberstone Clare E , Robertson Eileen Y , Wachsmuth Nadine B , Clark Sally A , McLean Blake D , Friedmann-Bette Birgit , Neya Mitsuo , Pottgiesser Torben , Schumacher Yorck O , Schmidt Walter F
Published: November 2013

Objective

To characterise the time course of changes in haemoglobin mass (Hbmass) in response to altitude exposure.

Methods

This meta-analysis uses raw data from 17 studies that used carbon monoxide rebreathing to determine Hbmass prealtitude, during altitude and postaltitude. Seven studies were classic altitude training, eight were live high train low (LHTL) and two mixed classic and LHTL. Separate linear-mixed models were fitted to the data from the 17 studies and the resultant estimates of the effects of altitude used in a random effects meta-analysis to obtain an overall estimate of the effect of altitude, with separate analyses during altitude and postaltitude. In addition, within-subject differences from the prealtitude phase for altitude participant and all the data on control participants were used to estimate the analytical SD. The ‘true’ between-subject response to altitude was estimated from the within-subject differences on altitude participants, between the prealtitude and during-altitude phases, together with the estimated analytical SD.

Results

During-altitude Hbmass was estimated to increase by ∼1.1%/100 h for LHTL and classic altitude. Postaltitude Hbmass was estimated to be 3.3% higher than prealtitude values for up to 20 days. The within-subject SD was constant at ∼2% for up to 7 days between observations, indicative of analytical error. A 95% prediction interval for the ‘true’ response of an athlete exposed to 300 h of altitude was estimated to be 1.1–6%.

Conclusions

Camps as short as 2 weeks of classic and LHTL altitude will quite likely increase Hbmass and most athletes can expect benefit.
Determinants of team-sport performance: implications for altitude training by team-sport athletes
Authors: Bishop David J , Girard Olivier
Published: November 2013

Team sports are increasingly popular, with millions of participants worldwide. Athletes engaged in these sports are required to repeatedly produce skilful actions and maximal or near-maximal efforts (eg, accelerations, changes in pace and direction, sprints, jumps and kicks), interspersed with brief recovery intervals (consisting of rest or low-intensity to moderate-intensity activity), over an extended period of time (1–2 h). While performance in most team sports is dominated by technical and tactical proficiencies, successful team-sport athletes must also have highly-developed, specific, physical capacities. Much effort goes into designing training programmes to improve these physical capacities, with expected benefits for team-sport performance. Recently, some team sports have introduced altitude training in the belief that it can further enhance team-sport physical performance. Until now, however, there is little published evidence showing improved team-sport performance following altitude training, despite the often considerable expense involved. In the absence of such studies, this review will identify important determinants of team-sport physical performance that may be improved by altitude training, with potential benefits for team-sport performance. These determinants can be broadly described as factors that enhance either sprint performance or the ability to recover from maximal or near-maximal efforts. There is some evidence that some of these physical capacities may be enhanced by altitude training, but further research is required to verify that these adaptations occur, that they are greater than what could be achieved by appropriate sea-level training and that they translate to improved team-sport performance.
Position statement—altitude training for improving team-sport players’ performance: current knowledge and unresolved issues
Authors: Girard Olivier , Amann Markus , Aughey Robert , Billaut François , Bishop David J , Bourdon Pitre , Buchheit Martin , Chapman Robert , D'Hooghe Michel , Garvican-Lewis Laura A , Gore Christopher J , Millet Grégoire P , Roach Gregory D , Sargent Charli , Saunders Philo U , Schmidt Walter , Schumacher Yorck O
Published: November 2013

Despite the limited research on the effects of altitude (or hypoxic) training interventions on team-sport performance, players from all around the world engaged in these sports are now using altitude training more than ever before. In March 2013, anAltitude Training and Team Sportsconference was held in Doha, Qatar, to establish a forum of research and practical insights into this rapidly growing field. A round-table meeting in which the panellists engaged in focused discussions concluded this conference. This has resulted in the present position statement, designed to highlight some key issues raised during the debates and to integrate the ideas into a shared conceptual framework. The present signposting document has been developed for use by support teams (coaches, performance scientists, physicians, strength and conditioning staff) and other professionals who have an interest in the practical application of altitude training for team sports. After more than four decades of research, there is still no consensus on the optimal strategies to elicit the best results from altitude training in a team-sport population. However, there are some recommended strategies discussed in this position statement to adopt for improving the acclimatisation process when training/competing at altitude and for potentially enhancing sea-level performance. It is our hope that this information will be intriguing, balanced and, more importantly, stimulating to the point that it promotes constructive discussion and serves as a guide for future research aimed at advancing the bourgeoning body of knowledge in the area of altitude training for team sports.
Changes in salivary hormones, immunoglobulin A, and C-reactive protein in response to ultra-endurance exercises
Authors: Tauler Pedro , Martinez Sonia , Moreno Carlos , Martínez Pau , Aguilo Antoni
Published: November 2013

The aim of the study was to determine the influence of the exercise duration on the changes in salivary stress markers in response to ultra-endurance exercises. The study was developed in 2 ultra-endurance exercise tests: the Ultra-trail Serra de Tramuntana (UTST), a 104 km ultra-marathon competition (n = 64) and the 25 km Cabrera Open Water Race (COWR) (n = 43). Participants in the COWR completed the 25 km at a constant pace of 3 km/h (3K group) or 2.5 km /h (2.5K group). Saliva samples were taken before and after the exercises. Salivary flow rate as well as cortisol, testosterone, C-reactive protein (CRP), and immunoglobulin A (IgA) levels were measured. Salivary flow rate decreased after the UTST but increased after the COWR. The UTST induced significant increases in cortisol and CRP levels and decreases in testosterone and IgA levels. Furthermore, a negative correlation was found between the time the athletes took to complete the exercise and the changes in salivary cortisol. After the COWR, higher increases in salivary cortisol levels were observed in the 3K group than in the 2.5K group. A significant effect of exercise decreasing testosterone and IgA levels was observed in both groups. No changes in the CRP levels were observed during the COWR. In conclusion, shorter times to complete the ultra-endurance exercise were associated with higher increases in cortisol. However, no relationships were found between the time to complete the exercises and the changes in testosterone, CRP, and IgA levels.