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Oxidative Stress in Collegiate Cross Country Skiers in Mid- and Post-Seasons

Journal of Biosciences and Medicines 2024年第5期12卷 99-110页

作者： Scott P. Jerome Kriya L. Dunlap Ava M. Parrish Matthew L. Lowman Emily M. Shipman Lawrence K. Duffy Arleigh J. Reynolds Department of Chemistry & Biochemistry University of Alaska Fairbanks Fairbanks AK USA Institute of Arctic Biology University of Alaska Fairbanks Fairbanks AK USA Department of Biology & Wildlife University of Alaska Fairbanks Fairbanks AK USA Department of Veterinary Medicine University of Alaska Fairbanks Fairbanks AK USA

Purpose: The oxidative stress (OS) hypothesis of overtraining syndrome argues that increased production of free radicals through exercise cause muscle fatigue and damage resulting in lower athletic performance. Several studies have investigated OS immediately before and after exercise bouts in a training macrocycle. Our study aimed to compare OS of endurance athletes between a competition macrocycle and the immediate post-season recovery macrocycle. In addition, we aimed to identify athletes who experienced an unexplainable drop in athletic performance during the competition season in order to compare their OS to those who experienced no drop in performance. Methods: Fifteen members of the university of alaska fairbanks cross country ski team volunteered for this study. Blood samples were taken in early February (“mid-season”) and late April (“post-season”). Participants completed questionnaires regarding physical activity and athletic performance at the time of the blood draws. Plasma was analyzed for 4-hydroxynonenal (HNE), nitrotyrosine, nitric oxide (NOX), and superoxide dismutase (SOD). Significance was determined by Wilcoxon and Mann-Whitney tests. Results: Participants displayed significantly higher (p Conclusion: Signs of oxidative stress and mitigation during the post-season recovery macrocycle were higher in athletes who reported experiencing a drop in athletic performance during the competition season macrocycle.

关键词： Oxidative Stress 4-Hydroxynonenal Superoxide Dismutase Athletic Performance Training Macrocycle

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Estimating the subsolar magnetopause position from soft X-ray images using a low-pass image filter

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Earth and Planetary Physics 2024年第1期8卷 173-183页

作者： Hyangpyo Kim Hyunju K.Connor Jaewoong Jung Brian M.Walsh David Sibeck Kip D.Kuntz Frederick S.Porter Catriana K.Paw U Rousseau A.Nutter Ramiz Qudsi Rumi Nakamura Michael Collier Space Research Institute Austrian Academy of Sciences8042 GrazAustria Geophysical Institute University of Alaska FairbanksFairbanksAlaska 99775USA National Aeronautics and Space Administration(NASA)Goddard Space Flight Center GreenbeltMaryland 20771USA Astronomy Department University of Maryland College ParkCollege ParkMaryland 20742USA Center for Space Physics Boston UniversityBostonMassachusetts 02215USA Department of Physics and Astronomy Johns Hopkins UniversityBaltimoreMaryland 21218USA Howard university WashingtonDC 20059USA

The Lunar Environment heliospheric X-ray Imager(LEXI)and Solar wind Magnetosphere Ionosphere Link Explorer(SMILE)missions will image the Earth’s dayside magneto pause and cusps in soft X-rays after their respective launches in the near future,to specify glo bal magnetic reconnection modes for varying solar wind *** suppo rt the success of these scientific missions,it is critical to develop techniques that extract the magnetopause locations from the observed soft X-ray *** this research,we introduce a new geometric equation that calculates the subsolar magnetopause position(RS)from a satellite position,the look direction of the instrument,and the angle at which the X-ray emission is *** assumptions are used in this method:(1)The look direction where soft X-ray emissions are maximized lies tangent to the magnetopause,and(2)the magnetopause surface near the subsolar point is almost spherical and thus RSis nea rly equal to the radius of the magneto pause *** create synthetic soft X-ray images by using the Open Geospace General Circulation Model(OpenGGCM)global magnetohydrodynamic model,the galactic background,the instrument point spread function,and Poisson *** then apply the fast Fourier transform and Gaussian low-pass filte rs to the synthetic images to re move noise and obtain accurate look angles for the soft X-ray pea *** the filte red images,we calculate RS and its accuracy for different LEXI locations,look directions,and solar wind densities by using the OpenGGCM subsolar magnetopause location as ground *** method estimates RS with an accuracy of10 *** accuracy improves for greater solar wind densities and during southward interplanetary magnetic *** method ca ptures the magnetopause motion during southwa rd interplaneta ry magnetic field ***,the technique will enable quantitative analysis of the magnetopause motion and help reveal the daysi

关键词： soft X-ray magnetopause reconnection low-pass filter LEXI SMILE

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Freeze-thaw cycles and associated geomorphology in a post-glacial environment:current glacial,paraglacial,periglacial and proglacial scenarios at Pico de Orizaba volcano,Mexico

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Journal of Mountain Science 2024年第6期21卷 1954-1977页

作者： Víctor SOTO Carlos M.WELSH R. Kenji YOSHIKAWA Hugo DELGADO GRANADOS Centro de Ciencias de la Tierra Universidad VeracruzanaCircuito Gonzalo Aguirre BeltránS/NZona Universitaria91090XalapaMéxico Water and Environmental Research Center University of Alaska FairbanksFairbanksAlaska 99775USA Instituto de Geofísica Universidad Nacional Autónoma de MéxicoCiudad de México 04150México Department of Earth and Environmental Sciences Ludwig Maximilians UniversitätMunich 80333Germany

The glacial history of Pico de Orizaba indicates that during the Last Glacial Maximum,its icecap covered up to~3000 m asl;due to the air temperature increasing,its main glacier has retreated to 5050 m *** retraction of the glacier has left behind an intense climatic instability that causes a high frequency of freeze-thaw cycles of great intensity;the resulting geomorphological processes are represented by the fragmentation of the bedrock that occupies the upper parts of the *** is a notable lack of studies regarding the fragmentation and erosion occurring in tropical high mountains,and the associated geomorphological risks;for this reason,as a first stage of future continuous research,this study analyzes the freezing and thawing cycles that occur above 4000 m asl,through continuous monitoring of surface ground *** results allow us to identify and characterize four zones:glacial,paraglacial,periglacial and *** was found that the paraglacial zone presents an intense drop of temperature,of up to~9℃ in only sixty *** rock fatigue and intense freeze-thaw cycles that occur in this area are responsible for the high rate of rock disintegration and represent the main factor of the constant slope dynamics that occur at the *** activity decreases,both in frequency and intensity,according to the distance to the glacier,which is where the temperature presents a certain degree of stability,until reaching the proglacial zone,where cycles are almost non-existent,and therefore there is no gelifraction *** geomorphological processes have resulted in significant alterations to the mountain slopes,which can have severe consequences in terms of risk and water.

关键词： Freeze-Thaw Gelifraction Mountain mechanical erosion Periglacial geomorphology Postglacial scenarios

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Projected Changes in Extreme Event Indices for alaska

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Atmospheric and Climate Sciences 2024年第2期14卷 191-209页

作者： John E. Walsh Kyle Redilla Norman Shippee Lukas Cheung David Bigelow Ronni Wilcock International Arctic Research Center University of Alaska Fairbanks Fairbanks USA Stantec Ottawa Canada Stantec Montreal Canada Stantec Calgary Canada Two Bears Environmental Consulting Anchorage USA

As climate has warmed in recent decades, alaska has experienced a variety of high-impact extreme events that include heat waves, wildfires, coastal storms and freezing rain. Because the warming is projected to continue, it is essential to consider future changes when planning adaptation actions and building resilience. In this study, we synthesize information on future changes in extreme events in alaska from an ensemble of regional climate model simulations performed as part of Arctic-CORDEX (Coordinated Regional Climate Downscaling Experiment). A set of 13 extreme event indices, based on those developed by the World Climate Research Programme’s Expert Team on Climate Change Detection and Indices (ETCCDI), are evaluated from the Arctic-CORDEX output for alaska. Of the 13 indices, six pertain to temperature, five to total precipitation, one to wind and one to snow. The results for locations in seven different climate zones of alaska include large increases (5˚C - 10˚C) in the temperature thresholds for the five hottest and coldest days of the year, and large increases in warm spell duration and decreases in cold spell duration. Changes in the cold day temperature threshold are generally larger than the changes in the hot day temperature threshold, consistent with the projections of a stronger warming in winter than in summer in alaska yearly maximum 1-day and 5-day precipitation amounts as well as the yearly number of consecutive wet days are projected to increase at all locations. The indices for heavy snow days and high-wind days show mixed changes, although the results indicate increases in heavy snow days at the more northern locations and increases in windy days at coastal locations. The changes in the extreme event indices continue through 2100 under the higher-emission (RCP 8.5) emission scenario, while the changes generally stabilize under the lower-emission (RCP 4.5) scenario. .

关键词： Extreme Events Temperature Precipitation alaska Climate

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Metal-organic frameworks for CO2 photoreduction

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Frontiers in Energy 2019年第2期13卷 221-250页

作者： Lei ZHANG Junqing ZHANG Department of Mechanical Engineering University of Alaska Fairbanks Fairbanks AK 99775 USA

Metal-organic frameworks (MOFs) have attracted much attention because of their large surface areas, tunable structures, and potential applications in many areas. In recent years, MOFs have shown much promise in CO2 photoreduction. This review summarized recent research progresses in MOF-based photocatalysts for photocatalytic reduction of CO2. Besides, it discussed strategies in rational design of MOF-based photocatalysts (functionalized pristine MOFs, MOF-photosensitizer, MOF-semiconductor, MOF-metal, and MOF-carbon materials composites) with enhanced performance on CO2 reduction. Moreover, it explored challenges and outlook on using MOF-based photocatalysts for CO2 reduction.

关键词： metal-organic frameworks (MOFs) photoca-talysis CO2 photoreduction composite

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nvestigating the role of exiting vehicles and turn indicator usage in gap acceptance at single-lane roundabouts

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Frontiers of Structural and Civil Engineering 2017年第1期11卷 8-16页

作者： Nathan P. BELZ Civil and Environmental Engineering University of Alaska - Fairbanks Fairbanks AK 99775-5960 USA

Roundabouts are becoming a preferred form of intersection control type due to their safety and capacity benefits. Yield control at roundabout entries inherently reduces fuel consumption and emissions when compared to other conventional intersection types. However, these benefits can be limited by poor driver behavior and judgment when entering the roundabout. This research addresses the nature of gap distributions and use of turn indicators by exiting vehicles at three single-lane roundabouts in Vermont, New York, and alaska. Presented here is a comparison of vehicle headways measured at two different locations in each roundabout. Rejected headways are analyzed in the context of priority abstaining events when entering drivers yield to vehicles exiting on the same leg of the roundabout suggesting that ＂true＂ critical gaps are being overestimated. Results indicate that exiting vehicles, particularly those that do not use their turn indicators when departing from the major-stream of traffic have an influence on the entry decision of drivers on the same approach. This behavior is of particular concern for intersection efficiency （i.e., delay） and sustainability （i.e., excess fuel consumption and emissions）. Results prompt the consideration of more consistent guidance on and enforcement of turn indicator use during roundabout negotiations.

关键词： roundabouts exiting vehicles turn indicator use headways

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Low-salinity-based enhanced oil recovery literature review and associated screening criteria

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Petroleum Science 2019年第6期16卷 1344-1360页

作者： Mukul Chavan Abhijit Dandekar Shirish Patil Santanu Khataniar Department of Petroleum Engineering University of Alaska FairbanksFairbanksAKUSA

A thorough literature review is conducted that pertains to low-salinity-based enhanced oil recovery(EOR).This is meant to be a comprehensive review of all the refereed published papers,conference papers,master’s theses and other reports in this *** review is specifically focused on establishing various relations/characteristics or"screening criteria"such as:(1)classification/grouping of clays that have shown or are amenable to low-salinity benefits;(2)clay types *** of residual oil saturations;(3)API gravity and down hole oil viscosity range that is amenable for low salinity;(4)salinity range for EOR benefits;(5)pore sizes,porosity,absolute permeability and wettability range for low-salinity EOR;(6)continuous low-salinity injection ***-wise injection;(7)grouping of possible low-salinity mechanisms;(8)contradictions or similarities between laboratory experiments and field evidence;and(9)compositional variations in tested low-salinity waters.A proposed screening criterion for low-salinity waterflooding is *** can be concluded that either one or more of these mechanisms,or a combination thereof,may be the case-specific mechanism,i.e.,depending on the particular oil–brine–rock(OBR)system rather than something that is"universal"or universally ***,every OBR system that is unique or specific ought to be individually investigated to determine the benefits(if any)of low-salinity water injection;however,the proposed screening criteria may help in narrowing down some of the dominant responsible *** this review primarily focuses on sandstones,given the prominence of carbonates containing^60%of the world’s oil reserves,a summary of possible mechanisms and screening criteria,pertaining to low-salinity waterflooding,for carbonates is also ***,the enhancement of polymer flooding by using low-salinity water as a makeup water to further decrease the residual oil saturation is also discussed.

关键词： Low salinity Waterflooding EOR Clays Screening criteria Mechanism

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A new design concept for a thermoelectric generator with multiscale,multiphase,multifunctional composites

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Clean Energy 2018年第2期2卷 154-166页

作者： Tinggang Zhang university of alaska fairbanks FairbanksAK99775USA

A new module design concept that integrates materials engineering with thermoelectric module optimization is *** concept transforms the gaps between thermoelements and couples into internal space/pores within the elements to eliminate heat loss and thus to enhance module *** effect of the internal pore structure on module performance was studied using two effective medium *** modeling results demonstrated that the power generation of the proposed module design increased by~8%and the efficiency increased>20%compared to those of the traditional module *** effect of the inclusion of the second solid phase in the composite on module performance was also studied using nine different high-efficiency thermoelectric materials as the *** modeling results showed that further increase in module performance up to~50%that of the traditional module design can be achieved.

关键词： thermoelectric composite thermopower thermal conductivity conversion efficiency power genera-tion module design optimization

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Uncertainty quantification in the Permian Basin using conventional and modified bootstrap methodology

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Petroleum Research 2023年第4期8卷 439-454页

作者： Chukwuemeka O.Okoli Scott D.Goddard Obadare O.Awoleke Department of Petroleum Engineering University of Alaska FairbanksFairbanks99775AlaskaUSA National Energy Technology Laboratory 1450 Queen Avenue SWAlbany97321OregonUSA Department of Mathematics&Statistics University of Alaska FairbanksFairbanks99775AlaskaUSA

Various uncertainty quantification methodologies are presented using a combination of several deter-ministic decline curve analysis models and two bootstrapping *** probabilistic models are applied to 126 sample wells from the Permian *** are presented for 12-72 months of pro-duction hindcast given an average well production history of 103 *** on the coverage rate and the forecast error(with the coverage rate being more significant in our choice of the best probabilistic models)and using up to one-half of the available production history for a group of sample wells from the Permian Basin,we find that the CBM-SEPD combination is the best probabilistic model for the Central Basin Platform,the MBM-Arps combination is the best probabilistic model for the Delaware Basin,the CBM-Arps is the best probabilistic model for the Midland Basin,and the best probabilistic model for the overall Permian Basin is the CBM-Arps when early time data is used as hindcast and CBM-SEPD for when one-quarter to one-half of the data is used as *** three-quarters or more of the available production history is used for analysis,the MBM-SEPD probabilistic model is the best combination in terms of both coverage rate and forecast error for all the sub-basins in the *** novelty of this work lies in its extension of bootstrapping methods to other decline curve analysis *** work also offers the engineer guidance on the best choice of probabilistic model whilst attempting to forecast production from the Permian Basin.

关键词： Uncertainty quantification Machine learning Bootstrapping Reservoir forecasting Frequentist probabilistic models

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Cases and statistical study on Hot Flow Anomalies with Cluster spacecraft data

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Science China(Technological Sciences) 2012年第7期55卷 1402-1418页

作者： WANG Shan ZONG QiuGang ZHANG Hui Institute of Space Physics and Applied Technology Peking UniversityBeijing 100871China Geophysical Institute University of Alaska FairbanksFairbanksAK 99775USA

Hot Flow Anomalies (HFAs) are phenomena that frequently appear in the vicinity of the Earth's bow shock. We have identified 765 HFA events with Cluster spacecraft data from 2003 to 2009. We study the plasma and magnetic field variations during typical HFAs. Then we study the average structure of HFAs using the superposed epoch method during a 200 s time interval, with the HFA onset time as the epoch time. The results show that HFAs can be classified into four classes based on variations of the dynamic pressure over time, namely "-+" (down-up), "+-" (up-down), "M" (up-down-up) and "W" (up-down-up-down-up), where the letters represent similar shapes with the variation trends of the dynamic pressure. Trends of other parameters are highly related to those of the dynamic pressure with obvious characteristics of the classification. Moreover, statistical results suggest that the number of HFA events varies in years. Compared with the speed of solar wind and sunspot number, the number of HFA events in each year has positive correlation with the former, while it has little relation with the latter. The result of this paper will provide data base for further studies on the mechanisms of the formation, the structural evolution and other relative questions of HFAs.

关键词： Hot Flow Anomalies superposed epoch analysis bow shock discontinuity

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