bluuebunny/crossref_metadata_2025_split huggingface dataset:
High-magnitude head impact exposure in youth football
Authors: Campolettano Eamon T. , Gellner Ryan A. , Rowson Steven 
Published: October 2017

OBJECTIVEEven in the absence of a clinically diagnosed concussion, research suggests that neurocognitive changes may develop in football players as a result of frequent head impacts that occur during football games and practices. The objectives of this study were to determine the specific situations in which high-magnitude impacts (accelerations exceeding 40g) occur in youth football games and practices and to assess how representative practice activities are of games with regard to high-magnitude head impact exposure.METHODSA total of 45 players (mean age 10.7 ± 1.1 years) on 2 youth teams (Juniors [mean age 9.9 ± 0.6 years; mean body mass 38.9 ± 9.9 kg] and Seniors [mean age 11.9 ± 0.6 years; mean body mass 51.4 ± 11.8 kg]) wore helmets instrumented with accelerometer arrays to record head impact accelerations for all practices and games. Video recordings from practices and games were used to verify all high-magnitude head impacts, identify specific impact characteristics, and determine the amount of time spent in each activity.RESULTSA total of 7590 impacts were recorded, of which 571 resulted in high-magnitude head impact accelerations exceeding 40g (8%). Impacts were characterized based on the position played by the team member who received the impact, the part of the field where the impact occurred, whether the impact occurred during a game or practice play, and the cause of the impact. High-magnitude impacts occurred most frequently in the open field in both games (59.4%) and practices (67.5%). “Back” position players experienced a greater proportion of high-magnitude head impacts than players at other positions. The 2 teams in this study structured their practice sessions similarly with respect to time spent in each drill, but impact rates differed for each drill between the teams.CONCLUSIONSHigh-magnitude head impact exposure in games and practice drills was quantified and used as the basis for comparison of exposure in the 2 settings. In this cohort, game impact rates exceeded those for practice. Back players, who were often positioned in the open field, were shown to experience elevated levels of head impact exposure relative to players at other positions. The analysis also suggests that practice intensity, which may be influenced by coaching style, may also affect high-magnitude head impact exposure. Future studies should investigate this aspect as a factor affecting head impact exposure.
Comparison of quadriceps, hamstring, and gastrocnemius muscle co-activation in balance exercises
Authors: Park Sun-Ju , Shim Su-Jin , Choi Bo-Ram 
Published: October 2017

BACKGROUND: When various balance exercises are combined with strengthening or stretching exercises, the specific effects of any individual balance exercise are unclear. OBJECTIVE: The purpose of this study was to compare muscle activation and ratio in the quadriceps, hamstring, and gastrocnemius muscles in balance exercises. METHODS: In total, 20 healthy volunteers participated. The balance exercises consisted of standing on one-leg stand, a lunge, and trunk rotation. Electromyography data were collected from lateral quadriceps (LQ), lateral hamstring (LH), lateral gastrocnemius (LG), medial quadriceps (MQ), medial hamstring (MH), and medial gastrocnemius (MG). One-way repeated-measures analysis of variance was used to assess the statistical significance of the muscle activation, muscle co-activation, and the muscle activation/co-activation ratio in the balance exercises. RESULTS: Compared with the other exercises, co-activation of the MQMH, LQLH, and LHLG increased significantly during the lunge ([Formula: see text] 0.05). During the lunge, the increase in LQLH and LHLG co-activation was significantly greater than that in MQMH and MHMG co-activation ([Formula: see text] 0.05). CONCLUSIONS: Co-activation of lateral muscles was greater than in the medial muscles during lunge exercises with repeated lunge exercise potentially causing lateral knee joint compression. Therefore, physical therapists and/or athletic trainers should pay specific attention to use of lunge exercise within the framework of balance exercise program.
An intelligent IoT emergency vehicle warning system using RFID and Wi-Fi technologies for emergency medical services
Authors: Lai Yeong-Lin , Chou Yung-Hua , Chang Li-Chih 
Published: October 2017

BACKGROUND: Collisions between emergency vehicles for emergency medical services (EMS) and public road users have been a serious problem, impacting on the safety of road users, emergency medical technicians (EMTs), and the patients on board. OBJECTIVE: The aim of this study is to develop a novel intelligent emergency vehicle warning system for EMS applications. METHODS: The intelligent emergency vehicle warning system is developed by Internet of Things (IoT), radio-frequency identification (RFID), and Wi-Fi technologies. RESULTS: The system consists of three major parts: a system trigger tag, an RFID system in an emergency vehicle, and an RFID system at an intersection. The RFID system either in an emergency vehicle or at an intersection contains a controller, an ultrahigh-frequency (UHF) RFID reader module, a Wi-Fi module, and a 2.4-GHz antenna. In addition, a UHF ID antenna is especially designed for the RFID system in an emergency vehicle. The IoT system provides real-time visual warning at an intersection and siren warning from an emergency vehicle in order to effectively inform road users about an emergency vehicle approaching. CONCLUSION: The developed intelligent IoT emergency vehicle warning system demonstrates the capabilities of real-time visual and siren warnings for EMS safety.
Connecting the First Galaxies with Ultrafaint Dwarfs in the Local Group: Chemical Signatures of Population III Stars
Authors: Jeon Myoungwon , Besla Gurtina , Bromm Volker 
Published: October 2017

Abstract
We investigate the star formation history (SFH) and chemical evolution of isolated analogs of Local Group (LG) ultrafaint dwarf galaxies (UFDs; stellar mass range of

) and gas-rich, low-mass dwarfs (Leo P analogs; stellar mass range of

). We perform a suite of cosmological hydrodynamic zoom-in simulations to follow their evolution from the era of the first generation of stars down to z = 0. We confirm that reionization, combined with supernova (SN) feedback, is primarily responsible for the truncated star formation in UFDs. Specifically, halos with a virial mass of

form

of stars prior to reionization. Our work further demonstrates the importance of Population III stars, with their intrinsically high

yields and the associated external metal enrichment, in producing low-metallicity stars (

) and carbon-enhanced metal-poor (CEMP) stars. We find that UFDs are composite systems, assembled from multiple progenitor halos, some of which hosted only Population II stars formed in environments externally enriched by SNe in neighboring halos, naturally producing extremely low metallicity Population II stars. We illustrate how the simulated chemical enrichment may be used to constrain the SFHs of true observed UFDs. We find that Leo P analogs can form in halos with

(z = 0). Such systems are less affected by reionization and continue to form stars until z = 0, causing higher-metallicity tails. Finally, we predict the existence of extremely low metallicity stars in LG UFD galaxies that preserve the pure chemical signatures of Population III nucleosynthesis.
The Formation of Mini-Neptunes
Authors: Venturini Julia , Helled Ravit 
Published: October 2017

Abstract
Mini-Neptunes seem to be common planets. In this work we investigate the possible formation histories and predicted occurrence rates of mini-Neptunes, assuming that the planets form beyond the iceline. We consider pebble and planetesimal accretion accounting for envelope enrichment and two different opacity conditions. We find that the formation of mini-Neptunes is a relatively frequent output when envelope enrichment by volatiles is included, and that there is a “sweet spot” for mini-Neptune formation with a relatively low solid accretion rate of ∼10−6
M
⊕ yr−1. This rate is typical for low/intermediate-mass protoplanetary disks and/or disks with low metallicities. With pebble accretion, envelope enrichment and high opacity favor the formation of mini-Neptunes, with more efficient formation at large semimajor axes (∼30 au) and low disk viscosities. For planetesimal accretion, such planets can also form without enrichment, with the opacity being a key aspect in the growth history and favorable formation location. Finally, we show that the formation of Neptune-like planets remains a challenge for planet formation theories.
Dynamics of Large-scale Coronal Structures as Imaged during the 2012 and 2013 Total Solar Eclipses
Authors: Alzate Nathalia , Habbal Shadia R. , Druckmüller Miloslav , Emmanouilidis Constantinos , Morgan Huw 
Published: October 2017

Abstract
White light images acquired at the peak of solar activity cycle 24, during the total solar eclipses of 2012 November 13 and 2013 November 3, serendipitously captured erupting prominences accompanied by CMEs. Application of state-of-the-art image processing techniques revealed the intricate details of two “atypical” large-scale structures, with strikingly sharp boundaries. By complementing the processed white light eclipse images with processed images from co-temporal Solar Dynamics Observatory/AIA and SOHO/LASCO observations, we show how the shape of these atypical structures matches the shape of faint CME shock fronts, which traversed the inner corona a few hours prior to the eclipse observations. The two events were not associated with any prominence eruption but were triggered by sudden brightening events on the solar surface accompanied by sprays and jets. The discovery of the indelible impact that frequent and innocuous transient events in the low corona can have on large-scale coronal structures was enabled by the radial span of the high-resolution white light eclipse images, starting from the solar surface out to several solar radii, currently unmatched by any coronagraphic instrumentation. These findings raise the interesting question as to whether large-scale coronal structures can ever be considered stationary. They also point to the existence of a much larger number of CMEs that goes undetected from the suite of instrumentation currently observing the Sun.
Modeling the High-energy Emission in GRB 110721A and Implications on the Early Multiwavelength and Polarimetric Observations
Authors: Fraija N. , Lee W. H. , Araya M. , Veres P. , Duran R. Barniol , Guiriec S. 
Published: October 2017

Abstract
GRB 110721A was detected by the Gamma-ray Burst Monitor and the Large Area Telescope (LAT) on board the Fermi satellite and the Gamma-ray Burst Polarimeter on board the IKAROS solar mission. Previous analysis of this burst showed: (i) a linear polarization signal with position angle stable (

ϕ

p

=
160
°
±
11

) and high degree of

Π
=

84

−
28

+
16

%

, (ii) an extreme peak energy of a record-breaking 15 ± 2 MeV, and (iii) a subdominant prompt thermal component observed right after the onset of this burst. In this paper, the LAT data around the reported position of GRB 110721A are analyzed with the most recent software and then, the LAT light curve above 100 MeV is obtained. The LAT light curve is modeled in terms of adiabatic early-afterglow external shocks when the outflow propagates into a stellar wind. Additionally, we discuss the possible origins and also study the implications of the early-afterglow external shocks on the extreme peak energy observed at 15 ± 2 MeV, the polarization observations, and the subdominant prompt thermal component.
Structure of Exhausts in Magnetic Reconnection with an X-line of Finite Extent
Authors: Shepherd L. S. , Cassak P. A. , Drake J. F. , Gosling J. T. , Phan T.-D. , Shay M. A. 
Published: October 2017

Abstract
We present quantitative predictions of the structure of reconnection exhausts in three-dimensional magnetic reconnection with an X-line of finite extent in the out-of-plane direction. Sasunov et al. showed that they have a tilted ribbon-like shape bounded by rotational discontinuities and tangential discontinuities. We show analytically and numerically that this prediction is largely correct. When there is an out-of-plane (guide) magnetic field, the presence of the upstream field that does not reconnect acts as a boundary condition in the normal direction, which forces the normal magnetic field to be zero outside the exhaust. This condition constrains the normal magnetic field inside the exhaust to be small. Thus, rather than the ribbon tilting in the inflow direction, the exhaust remains collimated in the normal direction and is forced to expand nearly completely in the out-of-plane direction. This exhaust structure is in stark contrast to the two-dimensional picture of reconnection, where reconnected flux expands in the normal direction. We present analytical predictions for the structure of the exhausts in terms of upstream conditions. The predictions are confirmed using three-dimensional resistive-magnetohydrodynamic simulations with a finite-length X-line achieved using a localized (anomalous) resistivity. Implications to reconnection in the solar wind are discussed. In particular, the results can be used to estimate a lower bound for the extent of the X-line in the out-of-plane direction solely using single-spacecraft data taken downstream in the exhausts.
Enhanced Cement Bond Evaluation in Thick Casing Utilizing Guided Acoustic Modes Generated by Electromagnetic Acoustic Transducers
Authors: Patterson D. , Ingram S. , Matuszyk P. J. , Yao X. , Das R. , Steinsiek R. 
Published: October 2017

Abstract
Well integrity and zonal isolation are crucial in deepwater wells requiring accurate cement bond log analysis. These wells require high mud weights and/or thick-wall casing strings that can prevent the use of some tools and, in the best case, result in a significantly reduced response and senstivity to the presence of cement. Guided Shear Horizontal (SH) modes generated by electromagnetic acoustic transducers (EMATs) provide an enhanced dynamic range response and are immune to any borehole content, either liquid or gas.
The response of SH modes is evaluated over a range of different casing diameters and thicknesses commonly encountered in deepwater wells in Brazil. This analysis includes analytical and numerical modeling that shows the changing attenuation response to varying cement properties. The unique feature of the SH modes is their response to only a solid coupled to the casing, enabling a straightforward analysis and interpretation. These results are also compared to standard compressional attenuation, demonstrating the enhanced sensitivity that the EMAT measurement provides.
The results demonstrate that the enhanced dynamic range of the SH modes often provides 300% or larger cement attenaution response over the standard compressional methods. This enhanced SH mode range shows the ability to use these data to directly determine the shear modulus of the material coupled to the casing, enabling a straightforward method for determining the presence of cement and its properties in-situ. This approach contrasts with conventional ultrasonic systems that respond to the compressional impedance, which can often have complications with heavy settled-solids behind the pipe. In addition, a case study shows the ability to see the formation-squeeze in heavy wall pipe. This evidence demonstrates the ability of SH guided modes generated by EMATs to provide enhanced cement evaluation in thick-wall casing. These modes provide an enhanced dynamic range and a straightforward and unique means determining the presence of a solid and its properties.
Lessons Learned and Reduction in Rig Time with the Use of Water-Based Mud to Bottom Hole Drilling in the Pre-Salt
Authors: Vadinal R. B. , Fabri F. , Teixeira G. T. , Gonzaga K. A. , da Silva P. H. P 
Published: October 2017

Abstract
The drilling of the evaporitic section using water-based mud (WBM) was always a challenge: even though there are already some wells drilled with saturated aqueous fluid, their use still divides opinions within the technical-academic community of the oil industry. Basically, there are two currents: one that believes that salt drilling with WBM causes an enlargement so great that it becomes impracticable to cement the casing and, consequently, to obtain a leak off test (LOT) or a formation integrity test (FIT) sufficient for drilling of the next phase. The other line of thinking is based on that the break-in created by the WBM is similar to that caused by the synthetic-based mud (SBM) and this increase in diameter would not have a negative influence on the quality of the cementing job. In 2015-2016, Petrobras drilled 13 wells in Santos Basin Pre-Salt using WBM for bottom hole drilling (BHD). In this way, this work aims to report the lessons learned in each well, comparing fluid costs with correlation wells drilled with SBM's. The use of WBM, besides not negatively impacting the drilling time of the phases, allows a reduction of the costs with chemicals products and a decrease in equipment costs, since the drying system of cuttings is not used. In addition, rig and borehole cleaning are simpler and require less time and WBM is less aggressive for people working in direct contact with the drilling fluid. To compare the costs of fabrication and treatment of fluids, an average calculation was used for the correlation wells. Thus, an economy achieved is the difference between average cost for correlation wells and the well in question. The drilling of the evaporitic section with WBM's makes: (i) no significant salt washout than that obtained when using SBM and (ii) as WBM does not require a cuttings drying system, rate of penetration (ROP) obtained during a salt drilling are higher than those obtained when working with SBM. For the drilling of the carbonate reservoir, the performance of WBM is similar to that of SBM and the use of WBM in BHD allows faster fluid exchange and generates less residue for wells with open hole single completions. By drilling 13 wells using WBM, it was possible to save 576.9 hours of rig time.
Cableless Intelligent Well Completion Development Based on Reliability
Authors: Da Silva M. F. , Jacinto C. C. , Hernalsteens C. , Nobrega M. , Soares M. Defilippo , Schnitzler E. , Nardi L. B. 
Published: October 2017

Abstract
This paper describes how the Pre-Salt reservoir monitoring & control requirements in Brazil, and the pressure to minimize CAPEX, OPEX, and ABEX pushed for the development of a cableless intelligent well completion based on reliability. The development plan proposed is associated with an appropriate risk assessment to ensure lower risk at each project phase.
The X-ware (hardware, software and human) reliability methodology is used throughout the development. It starts with a complete understanding of environmental and operational conditions, needed/requested materials and well design. Then, reliability assessments based on physics-of-failure methods is used to incorporate reliability into the hardware design process and continuous time non-homogenous semi-Markov process to capture human/software reliability. Finally, to ensure a lower risk at each project phase, complexity theory is used to evaluate the overall risk.
This development of a cableless intelligent completion addresses monitoring and control for up to four reservoir zones on producing, injection and convertible wells, all of them in a subsea environment where scaling and lost circulation problems are likely to happen. Reliability of at least 90% in 30 years with 80% of confidence interval is the major challenge of this development. The critical paths to ensure the achievements are cableless telemetry and the energy harvesting for the life cycle of the well. The expected results for the development are: expedite technology readiness with lower risk during installation and higher availability during the life cycle of the well.
The development of new technologies using X-ware reliability methodology and technical risk as a process control variable is the main contribution of this paper.
An Integrated Field Development Methodology for Improving FEL1
Authors: Nunes Giovani , Costa André Luiz Hemerly , Romão Josenilton de Figueiredo 
Published: October 2017

Abstract
The discovery of an oil field results from extensive exploratory work, culminating in its declaration of commerciality. To estimate the recoverable volume of oil and determine the net present value (NPV) of the project, a conceptual study of the production system is made. Given the (inherent) uncertainties of the exploration stage, the information and models used to support such studies tend to have low accuracy. The treatment of uncertainties is done with additional information acquired along the project. This is the case of well tests to mitigate reservoir uncertainties. However, a methodology able to capture the most relevant aspects of the NPV through the integration of different disciplines (reservoir engineering, flow assurance, topsides, etc.), without this entailing lengthy and complex simulations, is still an unmet demand.
Looking for inspiration in analogous systems and successful projects is the usual way the industry deals with uncertainties, which is why the concepts for new projects tend to be similar to those of the past. While this attitude brings comfort to decision makers, there is a risk of losing the opportunity to add value to the project through a more profitable alternative concept.
In the case of large oil fields, most companies will try to urgently put them to production, since the postponement of revenue reduces its NPV. This can lead to the development of fast track projects, restricting the time of alternative studies. Again, it is important to improve the decision-making process.
This work aims to present a methodology for conceptual studies through the integrated simulation of different disciplines. This methodology uses the NPV as a parameter in the generation of exploratory numbers of pre-projects and creates a criterion for the selection of a subset to be evaluated in following phases. The aim is to evaluate, for example, the ideal number and capacity of platforms in a field, the convenience of "phasing" or not of the construction of wells, a criteria for choosing flexible or rigid risers, the gains obtained with the increase in diameter of risers and production lines, etc.