bluuebunny/crossref_metadata_2025 huggingface dataset:
Deep-Water Shipwreck Site Distribution: The Equation of Site Formation
Authors: Church Robert
Published: June 2014

In 2007, marine archaeologists with C & C Technologies published a debris distribution model from data collected during a Deep Shipwreck Project with the former U.S. Minerals Management Service and NOAA's Office of Ocean exploration and Research. The researchers have continued to refine the formula with additional shipwreck information. Studying the Gulfoil site at a depth of 534 meters Below sea Level (BSL), as part of the Reefs, Rigs and Wrecks Program illustrated that a large portion of associated wreck debris fell outside the predictive distribution model and more information was needed to account for all the debris associated with catastrophic sinking events.

Using additional standard equations in combination with the distribution model provided a greater understanding of the initial site formation. The information learned was then applied to other deep-water sites such as the passenger freighter Robert E. Lee and German U-boat, U-166 (both 1,400 meters BSL) to help draw a clearer picture of the site formation process for other deep-water sites.

Deep-water shipwrecks and associated debris often sit on the bottom with relatively little disturbance except for the natural bio-chemical deterioration. The distribution of shipwreck material can often be calculated mathematically as a function of heading, speed, time, and water depth. The Equation of Site Formation is a method to better understand deep-water site formation and the wrecking events themselves.
Dynamic Plastic Deformation of Deepwater Steel Catenary Risers under Extreme Cyclic Compressive Loading
Authors: Hu Guanyu , Campbell Mike , Huang Chaojun
Published: June 2014

Steel catenary risers (SCR) on a large heave motion vessel are susceptible to compression in the riser touch down zone (TDZ). Dynamic compression can lead to over stress under extreme or abnormal weather conditions. The response of an SCR under compression is highly nonlinear and sensitive to various factors. However, the current available industry design codes and practices do not provide a clear guidance to address the acceptability of compression, over stress and the resulting plastic strains. In addition, the current analysis method used in industry common practice cannot accurately capture the nonlinear behavior of SCR involving accumulated plastic deformation, hysteresis effects and local buckling.

In this paper, a finite element analysis (FEA) modeling method using combined beam and solid elements is presented that enables simulation of large plastic deformation, pipe ovality and local pipe buckling in the TDZ of a deepwater SCR. The model is developed using ABAQUS. The SCR nonlinear response is examined through dynamic analysis of a deepwater SCR hung-off a semi-submersible. The key analysis results are compared with a nonlinear beam element model. Moreover, dynamic ratcheting analysis under multiple plastic strain cycles using the proposed solid riser model is conducted to understand the plastic strain accumulation and to check the acceptability of survival response of deepwater SCR under a series of severe Hurricanes in its service life.

This paper presents the methodology of evaluating the compression and plastic deformation that could be experienced by deepwater SCRs, including modeling approach, analysis results, possible failure modes, and conclusions. The impact of the study findings on the robustness and suitability of SCRs for deepwater application are discussed.
Development of an LNG Tandem Offloading System Using Floating Cryogenic Hoses - Breaking the Boundaries of LNG Transfer in Open Seas
Authors: Mauriès Benjamin , Lirola François
Published: June 2014

This paper presents the extensive work performed to propose to the LNG industry an offloading solution fully compliant with EN1474 standard requirements using floating hoses. Between 2009 and 2013, a tandem offloading system using floating cryogenic flexible hoses developed and qualified to be able to transfer LNG in open seas. This arrangement was selected in order to combine the safety and the availability brought by the tandem configuration with the wide operational envelope provided by the use of floating hoses.

This system is composed of an innovative and compact hose storage system on the LNG Terminal allowing to store the hoses between two offloading operations, of a connection head (hose end termination piece) to ease the deployment/retrieval of the hoses and of a storage and maintenance platform for the connection head at the aft of the LNG Terminal, also allowing to replace a hose section in offshore conditions. On the LNG Carrier side, a bow loading platform is installed to ensure hoses connection even in exposed environmental conditions. The 20" ID cryogenic floating hoses to be used with this system has been developed and qualified in parallel with the development of the tandem system.

A red line for this development was to keep a similar level of safety, integrity and performance to onshore offloading operations. To fulfill this requirement, simple, robust and proven technologies have been considered for the main items of the system. The system incorporates a comprehensive panel of safety layers through monitoring, hardware, procedures and control philosophy providing protection for people and material during all steps of the offloading sequence. Regarding the performance, the system can transfer LNG at a flowrate of 10, 000 to 12, 000 m3/h using three hoses, which gives redundancy to transfer LNG even with one hose unavailable. To offer a high availability, dedicated solutions have been implemented in the system to withstand sea states with Hs up to 3.5 m for hoses connection and 4 m for cargo transfer and hoses disconnection.

This solution will help unlocking offshore stranded gas resources in many areas around the world through FLNG development.
Analytical Development of Seastate Limits Associated to the Abandonment Operations of a Structurally Compromised Subsea Well
Authors: Turner T. N. , Murdoch N.
Published: June 2014

When drilling a subsea well, a loss of structural integrity of the conductor can lead to a substantial reduction in the well's ability to resist the axial and lateral loads imposed by the drilling riser and BOP. This can then lead to hazardous conditions and increased risks to the asset performing the drilling as well as the personnel onboard. This may leave the operator with no choice but to abandon the well. In this situation, the hazards associated with the loss of integrity must also be considered when planning the abandonment operation itself. This paper presents a case study that details the analysis methods used to develop seastate limits for the abandonment of a subsea well with compromised structural integrity.

The well's high pressure and low pressure housings were observed by ROV inspection to have become un-latched during drilling. The inspection also revealed substantial conductor subsidence which suggested a failure of the 30" conductor and 20" surface casing cement jobs. Initial investigations indicated the well lacked the required levels of structural integrity to resist the loads involved with drilling to total depth. As a result, the decision was taken by the operator to suspend and then permanently abandon the well.

This paper discusses the technical approach used to develop the seastate limits imposed during the abandonment operation. The methodology utilized advanced non-linear finite element analysis techniques in conjunction with a novel statistical treatment of previously recorded in-situ BOP motion data.
Qualification Of A Cryogenic Floating Flexible Hose Enabling Safe And Reliable Offshore LNG Transfer For Tandem FLNG Offloading Systems
Authors: LAGARRIGUE Vincent , Hermary James , MAURIES Benjamin
Published: June 2014

Moving LNG production to an offshore setting certainly presents a serious set of challenges for the offshore oil and gas industry, particularly when it comes to the design and construction of FLNG facilities which need to maintain the utmost levels of safety and give increased flexibility to LNG production while withstanding the effects of winds, waves and currents in the open seas. With the first FLNG plants now in production and twenty other planned FLNG projects worldwide, it is safe to say that over the past few years these challenges have been overcome and these facilities have well and truly demonstrated their economic and technical viability to the industry. But while some challenges have certainly been met, others remain.

The environmental conditions of the current FLNG locations are at present quite mild and only require the use of the most straightforward technology for the unloading of the LNG, e.g. marine loading arms. But, with prospective new FLNG locations moving away from these ‘mild’ areas, to sites where sea states, wind and currents can be much more severe, only tandem LNG offloading systems appear to meet the challenges of the application as they improve safety, operability and availability.

Since 2009, Trelleborg has been developing floating cryogenic hoses which ensure LNG offshore transfer with minimum BOG generation, combine high flexibility, reliability and long service life, and also meet LNG operator and contractor's offloading requirements related to safety, flowrate capacity and operation availability. Through latest acquisition, this technology has been even further enhanced, with new parameters being put forward for the development of these hoses in order to become a key component in offloading systems for future offshore FLNG projects.

This white paper will discuss Trelleborg's 20" ID cryogenic hose development and qualification program and outline why tandem offloading solutions are a viable alternative for the industry – not only limiting downtime, but also improving safety. The paper will present in this case the innovative offshore LNG offloading system using cryogenic floating hoses which has been jointly developed with Saipem since 2009 and about to be qualified according to EN1474 standard requirements.
Using Technology Classification and Qualification Status as a Tool for Strategic Technology Screening and Selection
Authors: Huyse Luc
Published: June 2014

Technology Qualification (TQP) is the process of providing the evidence that a technology will function within specific operational limits with a specified level of confidence. A complete Technology Qualification is often initiated only once a Major Capital Project (MCP) has made a commitment to using the technology. At that stage of development, the TQ tools are used to manage the progression of the technology through the technology development stages (or technology readiness levels) and track the progress against the technology risk register and project schedule.

The focus of this paper is how the TQ tools set can be adapted and applied much earlier during the technology planning stage to determine possible opportunities for deployment. Early high-level risk assessment of new technology or new technology use can be very beneficial to non-technical communication of the technology risk to project decision executives. Using modified TQ tools to map out a clear technology road map for a MCP with both critical path as well as some of the possible fallback options provides a concise summary of the technology risks and landscape to the decision maker. Consistent application of these formats enables better business decision making.

Although the focus of the paper is on the conceptual and process level, some limited examples demonstrating the value of the approach will be provided.
Mars B- Olympus TLP Tow-Out Marks First Use of Synthetic Rigging; Finds Operational and HSSE Benefits
Authors: Shell Paul Dixon , Martinez Diego , Samson Justin Gilmore , Poroo Mike
Published: June 2014

This paper will demonstrate the benefits realized from a towing and positioning system made of synthetic ropes, rather than traditional steel wire rope, to deliver the MarsB-Olympus TLP for the critical inland tow, open water tow and positioning spread during the TLP Installation campaign. This is the first time Shell has used synthetic ropes for an installation of this magnitude.

Documented throughout the paper is the methodology used to evaluate the operational efficiencies of synthetic lines, Concept Proof Testing, the unique challenges of the inland tow, and the risk management plan required to make the offshore tow and positioning during hurricane season. Additionally, early engineering and design determined that using synthetic ropes would allow standardization of the towing lugs and the ability to replace unique and complex one-off components required for steel wire rope with a much simpler, proven design. In all three phases of the installation, the lines were rigged quickly and efficiently by a minimum of crew and without additional handling equipment. Most importantly, none of the synthetic ropes failed during the transportation and positioning phases.
Olympus TLP Operations Team – Enabling a community of excellence
Authors: Trussell Jay , Chevis Marc
Published: June 2014

How do you measure the success of a major deep water project? It is measured across the full range of its development phases—define, design, execute, and operate. Each of these phases requires effective integration of technical professionals ranging from geoscientists to surveillance engineers. Equally important is the integration of operations staff as early as the define phase. Building an operating organization which is effective in the early phases and grows to excel in the operate phase presents unique challenges. This paper focuses on building and enabling an operations organization during the execution and operation phases of the Mars B Development project. It will highlight a range of key enablers identified by the Olympus TLP operations team to create a community of excellence. These enablers ranged from organizational development to technology.

Organizational development is standard practice required for the creation of a new organization. The team put special emphasis on defining the right culture needed to be top quartile. That culture centers on caring, accountability, efficiency, and sustainability. Success in this area requires identifying and practicing individual behaviors supportive of the culture, and developing leadership attributes which enable the culture to grow.

Training and competency development are critical given the wide range of experience levels of the operating staff. The team identified unique competency requirements for the Olympus TLP which were beyond the core business unit requirements. Training was developed and delivered by senior operating personnel. Detailed computer-based training modules are used for more extensive training requirements, including the onboarding of new employees.

An integrated operations center in New Orleans merges asset support and operations personnel in a space designed around common work processes in support of the Olympus TLP. These groups are connected collectively: the TLP, subject matter experts, vendors and external support centers through collaborative work environment technology ranging from high-end video conferencing to real-time data sharing. The hub of this center is a remote control room which is an extension of the central control room on the TLP.
Ed-Drill MPD Dual Gradient Drilling for Challenging Pressure Regimes
Authors: Malt Roar , Stave Roger
Published: June 2014

MPD - Managed Pressure Drilling technologies have been successfully implemented over the last decade. The technique is also frequently used on floating drilling units. MPD is primarily understood as a technique where back pressure is applied in combination with a low density mud weight and a Rotating Control Device (RCD) - effectively raising the bell nipple into the derrick of the drilling rig.

However, within the MPD segment there is a sub-group defined as Dual Gradient Drilling (DGD). These techniques are specific for floating drilling units and allow the use of a higher, overbalanced mud weight.

EC-Drill is a technique that falls within the DGD segment. In its current form it is not providing "full dual gradient", instead it is eliminating the effect of dynamic circulating pressure (ECD) and enabling drilling with a close to constant bottom hole pressure (BHP). This may still impact well design by allowing casing points to be extended. The technique is ideal low mud weight environments and depleted fields where lowering the mud weight to allow for application of back-pressure may be impossible. EC Drill is also a valuable tool in loss regimes and it may be used to ensure good cement jobs in deep water preserving the integrity of the well.

A subsea mud pump is connected to the riser annulus where it controls annulus pressure by manipulating the fluid level within the riser - effectively lowering the bell nipple under water. The change in bottom hole pressure is directly related to the change in fluid level - or suction pressure of the subsea pump. Contrary to MPD with back pressure, this additional system or equipment is not part of the primary well barrier.

The EC-Drill technology has been successfully deployed on jack-ups and on s SEMIS in deep water.

The Paper will present the technology and some case histories
Continuous Motion Rig (CMR Technology) - A Step Change In Drilling Efficiency
Authors: Skjaerseth Odd B.
Published: June 2014

During the last 20 years the drilling industry has been through extensive mechanization and automation of tasks on the drill floor previously done manually. However the efficiency of operations has not improved through this development, neither has the development been able to improve well safety, an important aspect of drilling and well operations.

During the same period the costs of rig rental and services associated with drilling operations have had a significant increase. The increased cost for drilling is an essential aspect in the discussion of oil recovery from existing reservoirs and in the decision to explore new structures, thereby affecting the oil revenue of oil companies and governments. The importance of lowering drilling costs has been clearly pointed out at various industry conferences.

Mature oil provinces will experience an unnecessary decrease in oil production due to extensive drilling costs. The ability to reduce these costs is urgent and is heavily addressed by the major operators. Significant more drilling is necessary to prolong the production on the many mature fields As the drilling for oil and gas is moving into more demanding areas the need for safer drilling practices is imminent. The drilling industry has after several accidents a need for improved equipment that yields a higher standard in well safety.

West Drilling Products AS has invented and patented a new generation drilling technology - Continuous Motion Rig (CMR), a technology that promises a significant breakthrough in drilling efficiency, cost savings and well safety. CMR technology has a potential to reduce drilling time with 50 % and overall drilling costs with 40 – 50 %.

The main principle in this new breakthrough technology is to be able to run jointed drill pipe and casing continuously, to drill continuously while maintaining circulation. The CMR technology facilitates Underbalanced Drilling, MPD, and full snubbing capabilities. CMR will be the first fully robotize drilling process.

This paper will present the CMR technology, the development status and that the CMR Technology is a valuable and visible contribution of lowering drilling costs and introducing higher standard in well safety.
Safe and Efficient Tophole Drilling using Riserless Mud Recovery and Managed Pressure Cementing
Authors: Stave Roger , Nordas Philip , Fossli Borre , French Christopher
Published: June 2014

Riserless dual gradient technology enables drilling tophole with weighted and engineered mud without discharge to sea. A Suction Module is run and installed subsea. This has a collection chamber where well returns are collected and diverted to a subsea mud pump. A Mud Return Line allows pumping or lifting the mud and cuttings back to surface.

In this way a "closed loop system" is established; mud and cuttings are collected at seafloor and returned to the shakers as with post-BOP drilling techniques. The technique eliminates discharges of mud and cuttings at seafloor and thereby a weighted and engineered mud system may be used to solve difficult drilling challenges, improve drilling efficiency and safety.

Selection of the technology is typically driven by its ability to impact drilling efficiency and safety, but in environmental sensitive areas also by the fact that discharges to sea can be reduced or totally eliminated. The technology also in many cases allows setting of the 20" casing deeper, eliminating an extra liner across problem zones.

A spin-off technology is Managed Pressure Cementing - MPC; Once the first surface casing is landed and circulation of cement starts, the subsea mud pump is used to control annulus pressure. The pressure is controlled during circulation of the cement slurry to avoid fracture and losses. Performance of the MPC system provides evidence of successful placement of the cement and that pressure develops as planned during the setting time.

RMR provides superior hole quality and MPC improves the quality of the cement job. In combination the structural integrity of the surface casings are improved.

The Paper will present the RMR and MPC technologies and some case histories.
Subsea Water Treatment and Injection for IOR and EOR
Authors: Hegdal T. , Pinchin D.
Published: June 2014

The patented SWIT technology enables production and injection of clean sea water directly from the seabed, a flexible and cost effective solution. The technology, proven and ready to use, enables a step change in reservoir and asset management, accelerating production and increasing recovery. A new test proved that a combination of SWIT and membranes can produce low salinity and sulphate free water for a long time without any degradation in performance.

The SWIT technology offers a different approach to how reservoir and assets are managed and produced. Cleaning the surrounding sea water at the seabed and feeding directly into subsea injection wells is a completely different concept than the traditional topside approach. The benefits are significant from many aspects; reduced weight and area required topside; no long reach platform water injectors (WI) required; acceleration of production; increased recovery through flexible and phased deployment of the WI capacity required.

In 2009 – 2010, a 15 months full scale pilot test was carried out at the seabed in the Oslo fjord. The SWIT cleaned water was pumped to shore to NIVA Marine Research Centre for monitoring and testing. The results exceeded expectations and documented superior water quality for WI compared to traditional topside facilities. The Joint Industry Project (JIP) companies verified the results and technology is ready to be used in field applications. SWIT has been approved via technology qualification program with major oil companies.

The superior quality water from SWIT, including the ability to control the chlorine level very accurately, paves the way for producing low sulphate and low salinity water at seabed. A second test proved that SWIT feeding membranes make membranes last very long without any degradation in performance or maintenance requirement. SWIT combined with membranes therefore enables low sulphate and low salinity water injection from seabed. Currently planning is ongoing to design and build a full integrated sulphate free and low salinity water facility at the seabed.
Large Wire Rope Mooring Winch Drum Analysis And Design Criteria
Authors: Childers M.A
Published: June 2014

Flange splitting is the most common cause in mooring winch failure. Conventionally designed winches have failed on a number of occasions when sizes of, about 3" to 3 1/2" diameter wire ropes in lengths up to 10,000 feet were employed for mooring large construction barges and semi-submersible offshore drilling units. It is believed that this is due to improper approximation of the field loading patterns on the winch, inadequate knowledge of actual forces transmitted onto the flange and drum barrel of the winch and/or defects in the structural joint between the flange and the drum barrel. The available design methods are often empirical, modified or extrapolated from work done using very small wire ropes and drums a decade ago. The application of these techniques to a multilayered winch using large diameter wire rope has proven to be unrealistic. The authors have therefore developed a method to calculate the flange thrust load and the barrel external pressure for winches using large diameter wire ropes. Also, a general guide for design and analysis of such winches and the effect of the lateral modulus of elasticity of wire rope on the reduction in the layer tensions is presented.

INTRODUCTION

Large wire rope winches are increasingly coming into use for off-shore construction, pipe laying and drilling vessels operating in deep water due to the advantages of mooring with wire or a combination of chain and wire as opposed to mooring with chain only. Winches using about 3" to 3 1/2" diameter wire ropes up to five to ten thousand feet in length and stacked up to 15 or more layers under high tensions have been in use. And even larger winches are being contemplated as the search for hydrocarbons and minerals from and under the oceans expands into deeper waters. An industry-wide survey revealed that several large winches used on lay barges and semi-submersible drilling units have failed in service exposing the owners to millions of dollars in repair or replacement costs on these winches, plus the damaging downtime and delay to the programs on which these units may have been engaged. An in-depth study into the probable causes of these failures revealed that the state of the art in design of large winches, in practice, remained more or less empirical and that in some instances, quality control in manufacture was not being taken as seriously as this equipment warrants. In addition, neither the wire rope nor the winch manufacturers have established wire rope characteristics which are necessary for designing winches. The wire rope characteristics which vary according to rope formation, type of core, rope diameter and material properties of components, the number of layers, the number of wraps on each layer and the operational tension on each layer affect the over-all structural loading on a winch. It is known that as the rope gets larger and stiffer, as the number of layers increase and as the wire winding tension is maintained high, the resulting forces on the barrel and the side flanges likewise increase.
Assembly of the Magnus Tower
Authors: Carmichael A.J. , Garga P.K.
Published: June 2014

The heaviest one piece steel offshore structure in the world, for the B.P. Magnus Field in the North Sea, was completed in spring 1982. Important physical, structural and dimensional aspects, encountered during the assembly of the tower in the dry dock, are reviewed in this paper.

INTRODUCTION

The Magnus platform is a self-floating, X-braced, steel structure installed in British Petroleum's Magnus Field, which is located 200 km north east of the Shetlands Islands. The structure stands in a water depth of 186 metres, supports a topside load of 34,000 tonnes and is fixed to the seabed by 36 piles in clusters of 9 at each of the 4 legs.

The overall height of the structure is 210 ametres The base dimensions are 85 × 85 metres and the top deck dimensions are 56 × 62 metres. The large inherent buoyancy of this platform concept is provided by two 10.5 metre diameter legs extending the complete height of the structure and an 8 metre diameter by 70 metre long integral buoyancy tank located in the lower part of the platform. The structure has four outer frames, six levels of submerged plan bracings and two levels of above water plan bracings, which form the chords of the integral deck trusses.

The platform was built on its side in the dry dock facility of Highlands Fabricators at Nigg Bay, Scotland. Figs. 1 and 2' give an overall view of the tower in its construction orientation. The float-out weight of the complete tower was 40,400 tonnes.

BASIC PHILOSPOHY OF ERECTION SEQUENCE

The choice of erection sequence is the starting point for the fabricators overall project programme, which, in turn, forms the base for all pipemill, fabrication, painting and assembly programmes. It also highlights the requirements for subcontracting fabrication work.

Major considerations which lead to the adoption of a particular erection sequence are:Minimising the work which has to be carried out in-the-air. Welding at height is highly weather dependent, presents logistical problems in achieving good quality, requires special scaffolding arrangements and is labour intensive. For these reasons, it is time consuming and costly. This consideration generally results in a small number of very large assemblies, within the lifting capacities of available cranage. These assemblies should be as complete as possible with piping, equipment, anodes, paintwork, access ways and temporary scaffolding.Chosing erection items which have some inherent flexibility or are of simple structural form to enable fit-ups at the erection joints to be easily adjusted within the specification tolerances. If the item is excessively stiff or complex, or if the item requires a large number of fit-ups to be made to secure it into the structure, it can lead to poor fitups and high in-built stresses.Chosing erection items which are not difficult to assemble at ground level and move to the final erection location.
T Cell Activation Regulates CD6 Alternative Splicing by Transcription Dynamics and SRSF1
Authors: da Glória Vânia G. , Martins de Araújo Mafalda , Mafalda Santos Ana , Leal Rafaela , de Almeida Sérgio F. , Carmo Alexandre M. , Moreira Alexandra
Published: June 2014

The T cell-surface glycoprotein CD6 is a modulator of cellular responses and has been implicated in several autoimmune diseases such as multiple sclerosis, rheumatoid arthritis, and psoriasis. During Ag presentation, CD6 is targeted to the immunological synapse in a ligand binding-dependent manner, in which CD6 domain 3 directly contacts CD166, expressed on the APC. T cell activation results in the induction of CD6Δd3, an alternatively spliced isoform that lacks the ligand-binding domain and thus no longer localizes at the immunological synapse. In this study, we investigated the molecular mechanisms regulating the expression of CD6Δd3 upon human primary T cell activation. Using chromatin immunoprecipitation, we observed an increase in RNA polymerase II occupancy along the CD6 gene and augmented CD6 transcription. We showed that activation leads to transcription-related chromatin modifications, revealed by higher CD6 acetylation levels. Modulation of chromatin conformation using a histone deacetylase inhibitor that increases transcription rate causes an increase of exon 5 skipping. We further showed that the splicing factor SRSF1 binds to a regulatory element in CD6 intron 4, activating exon 5 splicing and promoting exon 5 inclusion. Concomitant with T cell activation-induced exon 5 skipping, we observed a downregulation of SRSF1. Using RNA immunoprecipitation, we showed that in activated T cells, SRSF1 recruitment to the CD6 transcript is impaired by increased chromatin acetylation levels. We propose that upon T cell activation, SRSF1 becomes limiting, and its function in CD6 exon 5 splicing is countered by an increase in CD6 transcription, dependent on chromatin acetylation.
Infiltrating Monocyte-Derived Macrophages and Resident Kupffer Cells Display Different Ontogeny and Functions in Acute Liver Injury
Authors: Zigmond Ehud , Samia-Grinberg Shany , Pasmanik-Chor Metsada , Brazowski Eli , Shibolet Oren , Halpern Zamir , Varol Chen
Published: June 2014

The liver has a remarkable capacity to regenerate after injury; yet, the role of macrophages (MF) in this process remains controversial mainly due to difficulties in distinguishing between different MF subsets. In this study, we used a murine model of acute liver injury induced by overdose of N-acetyl-p-aminophenol (APAP) and defined three distinct MF subsets that populate the liver following injury. Accordingly, resident Kupffer cells (KC) were significantly reduced upon APAP challenge and started recovering by self-renewal at resolution phase without contribution of circulating Ly6Chi monocytes. The latter were recruited in a CCR2- and M-CSF–mediated pathway at the necroinflammatory phase and differentiated into ephemeral Ly6Clo MF subset at resolution phase. Moreover, their inducible ablation resulted in impaired recovery. Microarray-based molecular profiling uncovered high similarity between steady-state KC and those recovered at the resolution phase. In contrast, KC and monocyte-derived MF displayed distinct prorestorative genetic signature at the resolution phase. Finally, we show that infiltrating monocytes acquire a prorestorative polarization manifested by unique expression of proangiogenesis mediators and genes involved with inhibition of neutrophil activity and recruitment and promotion of their clearance. Collectively, our results present a novel phenotypic, ontogenic, and molecular definition of liver-MF compartment following acute injury.
Optimizing stimulus repetition rate for recording ocular vestibular evoked myogenic potential elicited by air-conduction tone bursts of 500 Hz
Authors: Singh Niraj Kumar , Kadisonga Peter , Ashitha Palliyath
Published: June 2014

Amidst several publications reporting the effects of stimulus-related parameters on ocular vestibular evoked myogenic potential (oVEMP), the effect of the repetition rate on oVEMP responses has largely gone unexplored. Studies have used a repetition rate of ~5.1 Hz mainly due to a presumption that oVEMP, like cervical VEMP, should produce best responses for ~5 Hz, although there is paucity of experimental evidence to support this hypothesis. 52 healthy individuals in the age range of 17-35 years underwent air-conduction oVEMP elicited by 500 Hz tone-bursts using seven different repetition rates (3.1, 5.1, 10.1, 15.1, 20.1, 25.1 and 30.1 Hz). The results revealed a tendency for prolongation of latencies and reduction in amplitude with increasing repetition rate. However, significantly longer latencies were observed only for 20.1 Hz and larger amplitudes for 3.1 and 5.1 Hz (P<0.05). There was no significant difference between the rates of 3.1 Hz and 5.1 Hz. However 3.1 Hz produced poorer signal-to-noise ratio and required considerably longer time and thereby had lesser efficiency than 5.1 Hz (P<0.05). This would also result in higher fatigue and irritation levels considering the physical act of maintaining a supero-medial gaze. Thus the use of 5.1 Hz is recommended for clinical recording of oVEMP.
Implementation of Malaria Dynamic Models in Municipality Level Early Warning Systems in Colombia. Part I: Description of Study Sites
Authors: Ruiz Daniel , Cerón Viviana , Molina Adriana M. , Quiñónes Martha L. , Jiménez Mónica M. , Ahumada Martha , Gutiérrez Patricia , Osorio Salua , Mantilla Gilma , Connor Stephen J. , Thomson Madeleine C.
Published: June 2014

As part of the Integrated National Adaptation Pilot project and the Integrated Surveillance and Control System, the Colombian National Institute of Health is working on the design and implementation of a Malaria Early Warning System framework, supported by seasonal climate forecasting capabilities, weather and environmental monitoring, and malaria statistical and dynamic models. In this report, we provide an overview of the local ecoepidemiologic settings where four malaria process-based mathematical models are currently being implemented at a municipal level. The description includes general characteristics, malaria situation (predominant type of infection, malaria-positive cases data, malaria incidence, and seasonality), entomologic conditions (primary and secondary vectors, mosquito densities, and feeding frequencies), climatic conditions (climatology and long-term trends), key drivers of epidemic outbreaks, and non-climatic factors (populations at risk, control campaigns, and socioeconomic conditions). Selected pilot sites exhibit different ecoepidemiologic settings that must be taken into account in the development of the integrated surveillance and control system.
Viral Hemorrhagic Fever Cases in the Country of Georgia: Acute Febrile Illness Surveillance Study Results
Authors: Kuchuloria Tinatin , Imnadze Paata , Chokheli Maiko , Tsertsvadze Tengiz , Endeladze Marina , Mshvidobadze Ketevan , Clark Danielle V. , Bautista Christian T. , Fadeel Moustafa Abdel , Pimentel Guillermo , House Brent , Hepburn Matthew J. , Wölfel Silke , Wölfel Roman , Rivard Robert G.
Published: June 2014

Minimal information is available on the incidence of Crimean–Congo hemorrhagic fever (CCHF) virus and hantavirus infections in Georgia. From 2008 to 2011, 537 patients with fever ≥ 38°C for ≥ 48 hours without a diagnosis were enrolled into a sentinel surveillance study to investigate the incidence of nine pathogens, including CCHF virus and hantavirus. Of 14 patients with a hemorrhagic fever syndrome, 3 patients tested positive for CCHF virus immunoglobulin M (IgM) antibodies. Two of the patients enrolled in the study had acute renal failure. These 2 of 537 enrolled patients were the only patients in the study positive for hantavirus IgM antibodies. These results suggest that CCHF virus and hantavirus are contributing causes of acute febrile syndromes of infectious origin in Georgia. These findings support introduction of critical diagnostic approaches and confirm the need for additional surveillance in Georgia.
Placental Malaria is Rare Among Zanzibari Pregnant Women who did not Receive Intermittent Preventive Treatment in Pregnancy
Authors: Plotkin Marya , Said Khadija , Msellem Mwinyi I. , Chase Rachel P. , Hendler Natalie , Khamis Asma Ramadhan , Roman Elaine , Kitojo Chonge , Schwartz Alanna C. , Gutman Julie , McElroy Peter D.
Published: June 2014

Zanzibar has transitioned from malaria control to the pre-elimination phase, and the continued need for intermittent preventive treatment during pregnancy (IPTp) has been questioned. We conducted a prospective observational study to estimate placental malaria positivity rate among women who did not receive IPTp with sulfadoxine-pyrimethamine. A convenience sample of pregnant women was enrolled from six clinics on the day of delivery from August of 2011 to September of 2012. Dried placental blood spot specimens were analyzed by polymerase chain reaction (PCR); 9 of 1,349 specimens (0.7%; precision estimate = 0.2–1.1%) were PCR-positive for Plasmodium falciparum. Placental infection was detected on both Pemba (N = 3) and Unguja (N = 6). Placental malaria positivity in Zanzibar was low, even in the absence of IPTp. It may be reasonable for the Ministry of Health to consider discontinuing IPTp, intensifying surveillance efforts, and promoting insecticide-treated nets and effective case management of malaria in pregnancy.
Trypanosoma cruzi Meningoencephalitis in a Patient with Acquired Immunodeficiency Syndrome
Authors: Yasukawa Kosuke , Patel Shital M. , Flash Charlene A. , Stager Charles E. , Goodman Jerry C. , Woc-Colburn Laila
Published: June 2014

As a result of global migration, a significant number of people with Trypanosoma cruzi infection now live in the United States, Canada, many countries in Europe, and other non-endemic countries. Trypanosoma cruzi meningoencephalitis is a rare cause of ring-enhancing lesions in patients with acquired immunodeficiency syndrome (AIDS) that can closely mimic central nervous system (CNS) toxoplasmosis. We report a case of CNS Chagas reactivation in an AIDS patient successfully treated with benznidazole and antiretroviral therapy in the United States.
Recurrent winter warming pulses enhance nitrogen cycling and soil biotic activity in temperate heathland and grassland mesocosms
Authors: Schuerings J. , Jentsch A. , Hammerl V. , Lenz K. , Henry H. A. L. , Malyshev A. V. , Kreyling J.
Published: June 2014

Abstract. Winter air temperatures are projected to increase in the temperate zone, whereas snow cover is projected to decrease, leading to more extreme soil temperature variability, and potentially to changes in nutrient cycling. Therefore, we applied six winter warming pulses by infra-red heating lamps and surface heating wires in a field experiment over one winter in temperate heathland and grassland mesocosms. The experiment was replicated at two sites, a colder mountainous upland site with high snow accumulation and a warmer and dryer lowland site. Winter warming pulses enhanced soil biotic activity for both sites during winter, as indicated by 35% higher nitrogen (N) availability in the soil solution, 40% higher belowground decomposition and a 25% increase in the activity of the enzyme cellobiohydrolase. The mobilization of N differed between sites, and the incorporation of 15N into leaves was reduced by 31% in response to winter warming pulses, but only at the cold site, with significant reductions occurring for three of four tested plant species at this site. Furthermore, there was a trend of increased N leaching in response to the recurrent winter warming pulses. Overall, projected winter climate change in the temperate zone, with less snow and more variable soil temperatures, appears important for shifts in ecosystem functioning (i.e. nutrient cycling). While the effects of warming pulses on plant N mobilization did not differ among sites, reduced plant 15N incorporation at the colder temperate site suggests that frost damage may reduce plant performance in a warmer world, with important implications for nitrogen cycling and nitrogen losses from ecosystems.
Revisiting Mt. Kilimanjaro: Do n-alkane biomarkers in soils reflect the δ2H isotopic composition of precipitation?
Authors: Zech M. , Zech R. , Rozanski K. , Hemp A. , Gleixner G. , Zech W.
Published: June 2014

Abstract. During the last decade compound-specific deuterium (δ2H) analysis of plant leaf wax-derived n-alkanes has become a promising and popular tool in paleoclimate research. This is based on the widely accepted assumption that n-alkanes in soils and sediments generally reflect δ2H of precipitation (δ2Hprec). Recently, several authors suggested that δ2H of n-alkanes (δ2H,sub>n-alkanes) can also be used as proxy in paleoaltimetry studies. Here we present results from a δ2H transect study (~1500 to 4000 m a.s.l.) carried out on precipitation and soil samples taken from the humid southern slopes of Mt. Kilimanjaro. Contrary to earlier suggestions, a distinct altitude effect in δ2Hprec is present above ~2000 m a.s.l., i.e. δ2Hprec values become more negative with increasing altitude. The compound-specific δ2H values of nC27 and nC29 do not confirm this altitudinal trend, but rather become more positive both in the O-layers (organic layers) and the Ah-horizons (mineral topsoils). Although our δ2Hn-alkane results are in agreement with previously published results from the southern slopes of Mt. Kilimanjaro (Peterse et al., 2009, BG, 6, 2799–2807), a major re-interpretation is required given that the δ2Hn-alkane results do not reflect the δ2Hprec results. The theoretical framework for this re-interpretation is based on the evaporative isotopic enrichment of leaf water associated with transpiration process. Modelling results show that relative humidity, decreasing considerably along the southern slopes of Mt. Kilimanjaro (from 78% at ~ 2000 m a.s.l. to 51% at 4000 m a.s.l.), strongly controls δ2Hleaf water. The modelled δ2H leaf water enrichment along the altitudinal transect matches well the measured 2H leaf water enrichment as assessed by using the δ2Hprec and δ2Hn-alkane results and biosynthetic fractionation during n-alkane biosynthesis in leaves. Given that our results clearly demonstrate that n-alkanes in soils do not simply reflect δ2Hprec but rather δ2Hleaf water, we conclude that care has to be taken not to over-interpret δ2Hn-alkane records from soils and sediments when reconstructing δ2H of paleoprecipitation. Both in paleoaltimetry and in paleoclimate studies changes in relative humidity and consequently in δ2Hn-alkane values can completely mask altitudinally or climatically-controlled changes in δ2Hprec.
The effect of mixtures on colonisation of leaf litter decomposing in a stream and at its riparian zone
Authors: Abelho M.
Published: June 2014

Abstract. The effect of mixing litter on decomposition and colonisation has been the focus of many studies carried independently in terrestrial and aquatic ecosystems. Those studies are carried out in different regions, use different experimental protocols and methodologies for the assessment of additive or non-additive effects, and the conclusions on the effect of mixtures vary accordingly. In this study I tested the hypothesis, via a short-term decomposition experiment, that, when using the same experimental protocol, mixtures have similar additive effects on decomposition and associated biota in a stream and at its riparian zone. The effect of mixing litter was assessed by comparing values in mixtures with the average of single species, alder and poplar (method 1); comparing the value of a species in mixture with the value of that species alone (method 2); and by a graphical analysis of the average difference between observed and expected values and the 95% confidence intervals (method 3). Method 1 was the most conservative, detecting non-additive effects on macroinvertebrate abundance only; method 2 detected non-additive effects on both dry mass remaining and ergosterol, with differential responses of the leaf species and the habitat; and method 3 detected non-additive effects on all variables except ergosterol and percentage detritivore abundance and also identified different responses of the leaves exposed in the terrestrial and the aquatic habitats. These results show that (i) the methodology used to detect the effects of mixtures deeply influences the results obtained, and may partially explain the diversity of responses available in literature; and (ii) the effect of mixtures may differ in the stream and at the riparian area. However, the findings of the present work should be assessed in a larger-scale experiment in order to generalise the effects of mixing litter on terrestrial and aquatic habitats.
Feed prices and production costs on Spanish dairy farms
Authors: Casasnovas-Oliva Valero L. , Aldanondo-Ochoa Ana M.
Published: June 2014

This paper analyses the impact of livestock feed prices and pasture quality on the long and short-term costs of milk production in a region of Spain (Navarre). The empirical results are obtained from the estimation of a flexible short-run cost function, followed by the approximation of long-run equilibrium based on the quasi-fixed factors adjusted to their optimal levels. The results reveal a high sensitivity of milk production costs to changes in livestock feed prices due to two reasons. One is that, as milk production expands, it tends to become technologically more intensive. The other is that, in the current structure of dairy farming, land input is suboptimal, particularly in the case of large farms and areas of poor pasture. The results reveal that short-run substitution between feed and livestock is a potential strategy for farms to respond to feed price increases. They also suggest that structural policies designed to strengthen the dairy sector’s competitiveness should vary according to agro-climatic conditions. In areas of poor pasture, herd growth might be used as a long-term measure to increase competitiveness through economies of scale; while the alternatives for farms in better-endowed regions also include extensification of dairy production.