bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plasma soluble α-klotho protein levels in premature and term neonates: correlations with growth and metabolic parameters
Authors: Siahanidou Tania , Garatzioti Maria , Lazaropoulou Christina , Kourlaba Georgia , Papassotiriou Ioannis , Kino Tomoshige , Imura Akihiro , Nabeshima Yo-ichi , Chrousos George 
Published: June 2012

Objectiveα-Klotho (α-KL), a protein with antiaging properties, regulates phosphate, calcium, and bone metabolism, induces resistance to oxidative stress, and may participate in insulin signaling. The role of α-KL in neonates, known to be prone to metabolic disturbances and oxidative stress, is not known. The aim of this study was to evaluate circulating soluble α-KL concentrations in preterm and full-term neonates and unravel possible correlations with growth, metabolism, and indices of oxidative stress.DesignProspective study.MethodsPlasma-soluble α-KL levels were determined by specific ELISA in 50 healthy neonates (25 preterm, mean (s.d.) gestational age (GA) 33.7 (1.1) weeks, and 25 full-term infants) at days 14 and 28 of life. Associations of α-KL with anthropometric, metabolic parameters, and indices of oxidative stress were examined.Resultsα-KL levels were significantly higher in full-term than in preterm infants at both days 14 (1099 (480) pg/ml vs 884 (239) pg/ml respectively; P<0.05) and 28 (1277 (444) pg/ml vs 983 (264) pg/ml respectively; P<0.01). In both preterm and full-term infants, α-KL levels increased significantly from day 14 to 28 of life (P<0.001). Circulating α-KL concentrations correlated with GA (β=0.32, P=0.001), body weight (β=0.34, P=0.001), body length (β=0.33, P=0.001), 1,25-dihydroxy-vitamin D level (β=0.24, P<0.05), and malondialdehyde level (β=0.20, P<0.05) but not with glucose, insulin, or homeostasis model assessment index of insulin resistance values.ConclusionsSoluble α-KL levels rise as GA and postnatal age advance in neonates and may have an impact on vitamin D metabolism and oxidative stress. Whether α-KL may have a role in the regulation of infants' growth should be further studied.
Using Online Lectures to Make Time for Active Learning
Authors: Prunuske Amy J , Batzli Janet , Howell Evelyn , Miller Sarah 
Published: June 2012

Abstract
To make time in class for group activities devoted to critical thinking, we integrated a series of short online lectures into the homework assignments of a large, introductory biology course at a research university. The majority of students viewed the online lectures before coming to class and reported that the online lectures helped them to complete the in-class activity and did not increase the amount of time they devoted to the course. In addition, students who viewed the online lecture performed better on clicker questions designed to test lower-order cognitive skills. The in-class activities then gave the students practice analyzing the information in groups and provided the instructor with feedback about the students’ understanding of the material. On the basis of the results of this study, we support creating hybrid course models that allow students to learn the fundamental information outside of class time, thereby creating time during the class period to be dedicated toward the conceptual understanding of the material.
Ultraconserved Elements in the Human Genome: Association and Transmission Analyses of Highly Constrained Single-Nucleotide Polymorphisms
Authors: Chiang Charleston W K , Liu Ching-Ti , Lettre Guillaume , Lange Leslie A , Jorgensen Neal W , Keating Brendan J , Vedantam Sailaja , Nock Nora L , Franceschini Nora , Reiner Alex P , Demerath Ellen W , Boerwinkle Eric , Rotter Jerome I , Wilson James G , North Kari E , Papanicolaou George J , Cupples L Adrienne ,   Genetic Investigation of ANthropometric Traits (GIANT) Consortium, Murabito Joanne M , Hirschhorn Joel N 
Published: June 2012

AbstractUltraconserved elements in the human genome likely harbor important biological functions as they are dosage sensitive and are able to direct tissue-specific expression. Because they are under purifying selection, variants in these elements may have a lower frequency in the population but a higher likelihood of association with complex traits. We tested a set of highly constrained SNPs (hcSNPs) distributed genome-wide among ultraconserved and nearly ultraconserved elements for association with seven traits related to reproductive (age at natural menopause, number of children, age at first child, and age at last child) and overall [longevity, body mass index (BMI), and height] fitness. Using up to 24,047 European-American samples from the National Heart, Lung, and Blood Institute Candidate Gene Association Resource (CARe), we observed an excess of associations with BMI and height. In an independent replication panel the most strongly associated SNPs showed an 8.4-fold enrichment of associations at the nominal level, including three variants in previously identified loci and one in a locus (DENND1A) previously shown to be associated with polycystic ovary syndrome. Finally, using 1430 family trios, we showed that the transmissions from heterozygous parents to offspring of the derived alleles of rare (frequency ≤0.5%) hcSNPs are not biased, particularly after adjusting for the rates of genotype missingness and error in the data. The lack of transmission bias ruled out an immediately and strongly deleterious effect due to the rare derived alleles, consistent with the observation that mice homozygous for the deletion of ultraconserved elements showed no overt phenotype. Our study also illustrated the importance of carefully modeling potential technical confounders when analyzing genotype data of rare variants.
Gene Discovery Using Mutagen-Induced Polymorphisms and Deep Sequencing: Application to Plant Disease Resistance
Authors: Zhu Ying , Mang Hyung-gon , Sun Qi , Qian Jun , Hipps Ashley , Hua Jian 
Published: June 2012

AbstractNext-generation sequencing technologies are accelerating gene discovery by combining multiple steps of mapping and cloning used in the traditional map-based approach into one step using DNA sequence polymorphisms existing between two different accessions/strains/backgrounds of the same species. The existing next-generation sequencing method, like the traditional one, requires the use of a segregating population from a cross of a mutant organism in one accession with a wild-type (WT) organism in a different accession. It therefore could potentially be limited by modification of mutant phenotypes in different accessions and/or by the lengthy process required to construct a particular mapping parent in a second accession. Here we present mapping and cloning of an enhancer mutation with next-generation sequencing on bulked segregants in the same accession using sequence polymorphisms induced by a chemical mutagen. This method complements the conventional cloning approach and makes forward genetics more feasible and powerful in molecularly dissecting biological processes in any organisms. The pipeline developed in this study can be used to clone causal genes in background of single mutants or higher order of mutants and in species with or without sequence information on multiple accessions.
Parallel Genetic Changes and Nonparallel Gene–Environment Interactions Characterize the Evolution of Drug Resistance in Yeast
Authors: Gerstein Aleeza C , Lo Dara S , Otto Sarah P 
Published: June 2012

AbstractBeneficial mutations are required for adaptation to novel environments, yet the range of mutational pathways that are available to a population has been poorly characterized, particularly in eukaryotes. We assessed the genetic changes of the first mutations acquired during adaptation to a novel environment (exposure to the fungicide, nystatin) in 35 haploid lines of Saccharomyces cerevisiae. Through whole-genome resequencing we found that the genomic scope for adaptation was narrow; all adapted lines acquired a mutation in one of four late-acting genes in the ergosterol biosynthesis pathway, with very few other mutations found. Lines that acquired different ergosterol mutations in the same gene exhibited very similar tolerance to nystatin. All lines were found to have a cost relative to wild type in an unstressful environment; the level of this cost was also strongly correlated with the ergosterol gene bearing the mutation. Interestingly, we uncovered both positive and negative effects on tolerance to other harsh environments for mutations in the different ergosterol genes, indicating that these beneficial mutations have effects that differ in sign among environmental challenges. These results demonstrate that although the genomic target was narrow, different adaptive mutations can lead populations down different evolutionary pathways, with respect to their ability to tolerate (or succumb to) other environmental challenges.
Advances in Drilling and Evaluation Technology Create New Opportunities for Deepwater High-Pressure Wells
Authors: Edwards Hal , Rask James , Maehs Juergen , Wandstrat Matthew , Donadieu Brian 
Published: June 2012

Abstract
With well depths more commonly surpassing 30,000 ft below the mudline and ever-increasing water depths, exceedingly high-pressure environments present a new and challenging frontier for both operators and service companies. These new environments demand advances to existing technology to endure such pressure extremes while also accurately positioning the wellbore in the reservoir and obtaining critical geological information as the well is drilled.
A recent example in this pressure regime in the deepwater Gulf of Mexico will be reviewed. Pressure limits of the currently available technology are extended while successfully meeting drilling and evaluation goals. The drilling and evaluation technologies delivered real-time formation pressure and geological information, along with continuous directional control, enabling the operator to make vital decisions while drilling and for sidetrack evaluation. This real-time decision-making capability reduced the time required to execute casing point selection and subsequent sidetrack plans. Emphasis is placed on the need for operators and service companies alike to focus on thorough pre-job planning while paying close attention to complete system requirements high-pressure evaluation tools and detailed reviews.
Newer drilling opportunities, particularly in the deepwater arena, involve operating in extreme environments such as ultrahigh pressures, and demand different approaches to ensure flawless execution. This paper presents the variety of challenges, critical success factors, and lessons learned when drilling these ultra-high pressure wells in the demanding waters of the Gulf of Mexico. With downhole pressures approaching 30,000 psi and ever-increasing rig costs, the need for dependable drilling systems and integrated advanced formation evaluation technology is needed now more than ever.
The case results showcase the ability to set a new performance standard, extend the conventional operating envelop farther, and deliver answers while drilling.
Frac-Packing: Best Practices and Lessons Learned from over 600 Operations
Authors: Weirich John , Li Jeff , Abdelfattah Tarik , Pedroso Carlos 
Published: June 2012

Abstract
Frac-packing is a completion technique that merges two distinct processes: Hydraulic fracturing and gravel packing. The main challenge of a frac-pack completion is the successful creation of high conductivity fractures using the tip-screen out technique and placement of proppant within those fractures and the annulus between the screen and wellbore. This is further compounded by having to do so in an ultra high permeability environment, where high fluid leak-off rates are evident.
Since 1997, job data from more than 600 frac-packing operations worldwide have been compiled into a database. This paper reviews well information and key frac-packing parameters. Also summarized are engineering implementations and challenges, best practices, and lessons learned. Essential frac-pack design parameters attained from the step-rate-test (SRT) and mini-frac test are evaluated. These include bottom hole pressure, rock closure time and fracturing fluid efficiency. Down hole pressure and temperature are also discussed because of their importance to the post completion efficiency evaluation and fracturing fluid optimization phase.
Worldwide case histories are provided demonstrating how to deploy different frac-packing systems and pack the wellbore under extreme conditions with improved packing efficiency and a higher chance of success.
Advancement in Acid-Precursor Chemistry for Removal of Drill-in Fluid Filter Cake
Authors: Wang Xiaolan , Smith Kern , Cutler Jennifer , Beall Brian 
Published: June 2012

Abstract
It is challenging to remove filter cake uniformly and thoroughly from the production interval in horizontal and multi-lateral wells with heterogeneous formation characteristics. The inability to obtain complete filter cake removal is a common occurrence with the currently available reactive fluid systems. Another instance where conventional reactive systems are not adequate is when it’s desirable to spot the treatment fluid prior to running final completion. In some instances, this kind of operation can take several days.
Conventional practice to remove filter cake formed by water-based drill-in fluid usually includes strong mineral acids, buffered organic acids, oxidizers, enzymes, and chelating agents. These systems all have limitations that can result in non-uniform clean-up of the filter cake. Certain esters of organic acid have been investigated and used for filter cake removal to achieve better zonal coverage by delaying acid release. However, esters of formic acid generally hydrolyze too quickly, while acetic and lactic acid precursors hydrolyze more slowly but are not strong enough to effectively remove filter cake.
This paper presents a new delayed-release acid system that can generate an organic acid in situ. The system hydrolyzes more slowly than formates and lactates in the medium-to-high temperature ranges, and the generated organic acid is stronger than formic, lactic and acetic acid. Laboratory studies with a static HT/HP filter press demonstrated this new system can clean up filter cake effectively. Laboratory evaluation also demonstrated that polymer-specific enzymes can be added to the system to enhance clean-up efficiency because of its long delay time. Compared to conventional chemical methods of filter cake removal, this new delayed-release acid system provides a more efficient alternative, especially when the completion activity requires a long system delay time before the clean-up acid will be released across the entire production interval.
Innovative Whipstock Technology / Procedures Successfully Complete Challenging Low-Side, Uncemented Casing Exits: UK North Sea
Authors: Finlay Andrew , Sea Apache North , Bain James , Fairweather Alan , Ford James 
Published: June 2012

Abstract
Maximizing profitability in mature fields is dependent on reducing drilling and operational expenses to maintain optimized hydrocarbon production. As Forties field UK North Sea matures, drilling challenges are becoming increasingly more difficult and complex. Wellbore instability caused by the loss of reservoir pressure and anisotropic properties of overburden shale is a major issue as targets are pushed further away from the platform.
To continue successful development of Forties field, the operator is required to drill high-inclination deviated wellbores sidetracked from existing boreholes. The unstable shale outside of the sidetrack window requires a low-side casing exit. To optimize operations the sidetrack must be completed on the first attempt. When a first sidetrack fails, a second is often initiated approximately 10m (or interval thereof) further up in the wellbore with a higher mud weight. Unable to get more than a few feet away from the original wellbore within such a short distance, the new sidetrack can frequently re-enter the zone already damaged by the previous attempt and again runs into trouble. This broken formation becomes even more destabilized with increased mud weight.
To solve the operational / economic challenges, a unique wellbore departure system was developed to deliver fast, high-quality windows and sidetracks tailored specifically to meet operator’s low-side application objectives without compromising performance. The low-side exit requires a unique set of pre-job equipment modifications which is performed in the service provider’s workshop prior to shipping equipment to the well-site. The modification allows an upward force to be exerted at the tip of the whip face on setting the permanent packer / anchor thereby overcoming the natural gravitational forces. This upward force does not come into effect until the packer is energized, thus ensuring the whipstock assembly remains flexible enough to mitigate wellbore tortuosity encountered whilst running in the hole.
The system was successfully applied initially on three challenging uncemented whipstock sidetracks with single-trip window success (up to 77° inclination / 180° orientation). On all three jobs the anchoring and milling technology worked flawlessly with no issues when subsequently tripping directional BHA or liners through the window. Application engineers performed pre / post-job briefings with service provider’s rig site / offshore supervisors to ensure specific low-side exit guidelines were followed and that lessons learned or suggestions for improvement were captured and documented for prosperity.
The authors will present Forties field case studies that document procedural repeatability and how the tools and techniques could be used for any challenging low-side uncemented casing exits.
Review of Methods for Uniaxial Compressive Rock Strength Estimation in Deepwater Formation With Uncertainty Quantification in Wellbore Stability Analysis in Absence of Core Measurements
Authors: Kumar Rajeev Ranjan , Rao Dhiresh Govind 
Published: June 2012

Abstract
With the increase in deepwater exploration and unconventional tight gas exploration, wellbore stability analysis has emerged as a pivotal part of finalizing drilling programs. It becomes more important when inclined wellbores are drilled where stable mud weight windows are narrow. Wellbore stability analysis is conducted to validate calculated stress and rock properties against drilling observations. Uniaxial compressive rock strength (UCS) is an integral part of geomechanics studies involving mechanical earth modeling. Absence of direct core measurement brings uncertainty in the model. Presently, the industry uses different empirical relationships for estimation of UCS depending on formation type. It is critical to use appropriate relationship with minimum error and known quantification effects on final mud weight recommendation. Depositional sequence brings formation under different compaction regime of grains with interstitial pore fluid. Sandstone and shale are two common lithology found in India deepwater exploration field with intermediate siltstone. Validation of different models depends on porosity, volume of clay, saturation and sonic slowness response of formation. The present paper reviews these methods with four case studies from India and discusses how different models respond in deepwater formation sequences. Best method depending on range of volume of clay and porosity has been discussed in term of fuzzy logic. Mathematical model is build for uncertainty quantification of effect on mud weight optimization using different methods for UCS estimation is also discussed.
Horizontal Openhole Gravel Packing in Wells with Long Blank Pipe and Screen Sections
Authors: Costamte Y. R. , Trondsen A.. , Bergkvam R.. , Hodne H.. , Saasen A.. 
Published: June 2012

Abstract
For offshore developments it is anticipated that several wells will be completed using gravel packed sand screens divided by long blank pipe sections. Open-hole gravel packing has routinely been used as a sand control method in long horizontal wells. However handling long blank pipe sections represents a challenge. The length of blank pipe section could be 600 meters or longer. In such cases, the chart of the surface pump pressure versus the pumping time is different when compared with a typical profile from a horizontal gravel pack in a section without blank pipe. Typically, gravel pack sand moves in from heel to toe of a well for roughly half of the cross section area (alpha wave) followed by a final placement of the remaining part of the annulus from toe to heel (beta wave).
Since there is no flow through the pipe in the blank pipe section, the beta wave does not exist here, and its absence complicates the gravel placement in the heel region of the reservoir. On the upstream side of the blank pipe, the slurry is dehydrated through the screen. This slows down the rate in the area adjacent to the blank pipe where in turn a new alpha wave adjacent to the blank pipe starts. This process appears to continue until the majority of the area open to flow above the alpha wave adjacent to the blank pipe has been filled in. The beta wave adjacent to the screen on the upstream side of the blank pipe then continues normally.
The paper describes in detail a mechanistic model based on experiments which predicts the phenomena discussed above. This model for gravel placement has been validated both qualitatively and quantitatively with both laboratory and the North Sea field Heidrun data.
First Application of EC-Drill in Ultra Deepwater: Proven Subsea Managed Pressure Drilling Method
Authors: Rajabi M. Mir , Toftevåg K.. , Stave R. S. , Ziegler R.. 
Published: June 2012

Abstract
A previous attempt to drill an exploration well in ultra-deepwater in the Gulf of Mexico (GoM) did not reach its objective due to an inability to maintain a Water Based Mud (WBM) system light enough to maintain circulation. For the next round of exploration drilling, a system was sought that allows dynamic management of Equivalent Circulation Density (ECD). Conventional Rotating Control Device (RCD) based Constant Bottom Hole Pressure (CBHP) management systems were not suitable, as no drilling fluid light enough to manage ECD via backpressure could be applied for this campaign.
AGR has developed a pumped riser Managed Pressure Drilling (MPD) system named EC-Drill that facilitates an automated control of mud level inside the riser to a specific BHP set point to mitigate the problems of tight drilling margins in deep waters and low pressure reservoir. This allowed drilling from a semisubmersible with an adjustable mud level, effectively reducing BHP and managing ECD without using any types of backpressure devices. Fluid level inside the riser is adjusted by a field proven subsea pump system.
EC-Drill detects influxes and fluid losses quickly, allowing the driller to respond before significant problem occurs.
In this paper we will discuss how EC-Drill is planned to pave the way for the operator to access a previously unattainable ultra deepwater target. EC-Drill principles, well design, equipment, and planning will be covered.