检索结果-南通市图书馆

Analysis of ancient mass extinction recoveries in marine environments: generating strategies for managing outcomes of the current mass extinction

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

National Science Review 2024年第1期11卷 8-10页

作者： david j.Bottjer Department of Earth Sciences University of Southern California

The defining feature of a mass extinction and its associated recovery is the global amount of extinction that occurred[1]. However, there is finer-scale detail to the story, as seen in the ongoing modern mass extinction(the sixth mass extinction), which exhibits variable effects among marine ecosystems and environments, and hence geographic areas [1].

关键词：

The great catastrophe: causes of the Permo-Triassic marine mass extinction

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

National Science Review 2024年第1期11卷 37-50页

作者： Paul B.Wignall david P.g.Bond School of Earth & Environment University of Leeds School of Environmental Sciences University of Hull

The marine losses during the Permo-Triassic mass extinction were the worst ever experienced. All groups were badly affected, especially amongst the benthos(e.g. brachiopods, corals, bryozoans, foraminifers,ostracods). Planktonic populations underwent a fundamental change with eukaryotic algae being replaced by nitrogen-fixing bacteria, green-sulphur bacteria, sulphate-reducing bacteria and prasinophytes. Detailed studies of boundary sections, especially those in South China, have resolved the crisis to a ～55 kyr interval straddling the Permo-Triassic boundary. Many of the losses occur at the beginning and end of this interval painting a picture of a two-phase extinction. Improved knowledge of the extinction has been supported by numerous geochemical studies that allow diverse proposed extinction mechanisms to be studied. A transition from oxygenated to anoxic-euxinic conditions is seen in most sections globally, although the intensity and timing shows regional variability. Decreased ocean ventilation coincides with rapidly rising temperatures and many extinction scenarios attribute the losses to both anoxia and high *** kill mechanisms include ocean acidification for which there is conflicting support from geochemical proxies and, even less likely, siltation(burial under a massive influx of terrigenous sediment) which lacks substantive sedimentological evidence. The ultimate driver of the catastrophic changes at the end of the Permian was likely Siberian Trap eruptions and their associated carbon dioxide emissions with consequences such as warming, ocean stagnation and acidification. Volcanic winter episodes stemming from Siberian volcanism have also been linked to the crisis, but the short-term nature of these episodes(g evidence for rapid warming during the crisis makes this an unlikely cause. Finally, whilst the extinction is well studied in equatorial latitudes, a different history is found in northern Boreal latitudes

关键词： ocean anoxia ocean acidification siltation productivity collapse volcanic winter

Origins of perturbations in dayside equatorial ground magnetograms

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Earth and Planetary Physics 2024年第1期8卷 215-221页

作者： Syau-Yun W.Hsieh david g.Sibeck The johns Hopkins University Applied Physics Laboratory LaurelMarylandUSA NASA goddard Space Flight Center GreenbeltMarylandUSA

To determine the cause(s)of perturbations seen in dayside equatorial ground magnetograms,we conducted a systematic survey of simultaneous ground-based and geosynchronous satellite-based observations during the 90-day period from December 1,2020 to February 28,*** examined Huancayo ground magnetometer observations from 14:00:00 to 20:00:00 UT each day,during which Huancayo passed through local *** those data we chose perturbation events selected on the basis of large(>20 nT)event amplitude and classified the selected events as responding primarily to solar wind pressure,or to variations in the north/south component of the interplanetary magnetic field(IMF Bz),or perhaps in part to *** results show that an equivalent number of events were identified for each model during this 90-day *** in the lagged solar wind dynamic pressure routinely correspond to nearly simultaneous sudden impulses recorded at both geosynchronous orbit and on the *** in IMF Bz produce erosion signatures at geosynchronous orbit and can correspond to ground events if lag times for reconnection to enhance convection in the magnetosphere are taken into account.

关键词： dayside magnetosphere dayside equatorial ionosphere geosynchronous magnetic field

维普期刊数据库

Nutritional epigenetics education improves diet and attitude of parents of children with autism or attention deficit/hyperactivity disorder

在线全文

学校读者我要写书评

暂无评论

World journal of Psychiatry 2024年第1期14卷 159-178页

作者： Renee j Dufault Katherine M Adler david O Carpenter Steven g gilbert Raquel A Crider College of graduate Health Studies A.T.Still UniversityKirksvilleMO 63501United States Department of Research Food Ingredient and Health Research InstituteNaalehuHI 96772United States Department of Health Sciences University of New HavenWest HavenCT 06516United States Institute for Health and the Environment School of Public HealthState University of New YorkAlbanyNY 12222United States Department of Research Institute of Neurotoxicology and Neurological DisordersSeattleWA 98105United States Department of Statistics Food Ingredient and Health Research InstituteNaalehuHI 96772United States

BACKgROUND Unhealthy maternal diet leads to heavy metal exposures from the consumption of ultra-processed foods that may impact gene behavior across generations,creating conditions for the neurodevelopmental disorders known as autism and attention deficit/hyperactivity disorder(ADHD).Children with these disorders have difficulty metabolizing and excreting heavy metals from their bloodstream,and the severity of their symptoms correlates with the heavy metal levels measured in their *** may play a key role in helping parents reduce their ultra-processed food and dietary heavy metal intake by providing access to effective nutritional epigenetics *** To test the efficacy of nutritional epigenetics instruction in reducing parental ultra-processed food *** The study utilized a semi-randomized test and control group pretest-posttest pilot study design with participants recruited from parents having a learning-disabled child with autism or ***-two parents who met the inclusion criteria were randomly selected to serve in the test(n=11)or control(n=11)*** test group participated in the six-week online nutritional epigenetics tutorial,while the control group did *** efficacy of the nutritional epigenetics instruction was determined by measuring changes in parent diet and attitude using data derived from an online diet survey administered to the participants during the pre and post intervention *** intake scores were derived for both ultra-processed and whole/organic *** sample t-tests were conducted to determine any differences in mean diet scores within each *** There was a significant difference in the diet scores of the test group between the pre-and post-intervention *** parents in the test group significantly reduced their intake of ultra-processed foods with a preintervention diet score of 70(mean=5.385,SD=2.534)and a post-intervention diet score of 113(mean=8.692,SD=1.750)and the

关键词： Epigenomics Parenteral nutrition Autism Attention deficit/hyperactivity disorder Ultra-processed foods Heavy metals

A multi-sensor appiproach to calving detection

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Information Processing in Agriculture 2024年第1期11卷 45-64页

作者： Anita Z.Chang david L.Swain Mark g.Trotter Institute for Future Farming Systems School of HealthMedicaland Applied SciencesCentral Queensland UniversityRockhamptonQueensland 4700Australia

The advent of remote livestock monitoring systems provides numerous possibilities for improving on-farm productivity,efficiency,and *** potential application for these systems is for the detection of calving *** study describes the integration of data from multiple sensor sources,including accelerometers,global navigation satellite systems(gNsS),an accelerometer-derived rumination algorithm,a walk-over-weigh unit,and a weather station for parturition detection using a support vector machine *** best performing model utilised data from gNsS,the ruminating algorithm,and weather stations to achieve 98.6%accuracy,with 88.5%sensitivity and 100%*** topranking features of this model were primarily gNSS *** study provides an overview as to how various sensor systems could be integrated on-farm to maximise calving detection for improved production and welfare outcomes.

关键词： Accelerometer gNSS gPS Rumination Sensor WOW

Finding the magnetopause location using soft X-ray observations and a statistical inverse method

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Earth and Planetary Physics 2024年第1期8卷 184-203页

作者： gonzalo Cucho-Padin Hyunju Connor jaewoong jung Brian Walsh david g.Sibeck Space Weather Laboratory NASA Goddard Space Flight CenterGreenbeltMDUSA Department of Physics The Catholic University of AmericaWashingtonDCUSA geospace Physics Laboratory NASA Goddard Space Flight CenterGreenbeltMDUSA Astronomy Department University of Maryland College ParkCollege ParkMDUSA Center for Space Physics Department of Mechanical EngineeringBoston UniversityBostonMAUSA

Variability in the location and shape of the dayside magnetopause is attributed to magnetic reconnection,a fundamental process that enables the transfer of mass,energy,and momentum from the solar wind into the *** spatial and temporal properties of the magnetopause,under varying solar and magnetospheric conditions,remain largely unknown because empirical studies using in-situ observations are challenging to *** wide field-of-view(FOV)imaging is the only means to simultaneously observe the spatial distribution of the plasma properties over the vast dayside magnetospheric region and,subsequently,quantify the energy transport from the interplanetary medium into the terrestrial *** upcoming missions,ESA/CAS SMILE and NASA’s LEXI will provide wide-field imagery of the dayside magnetosheath in soft X-rays,an emission generated by charge exchange interactions between high charge-state heavy ions of solar wind origin and exospheric neutral ***-cadence two-dimensional observations of the magnetosheath will allow the estimation of dynamic properties of its inner boundary,the magnetopause,and enable studies of its response to changes in the solar wind dynamic pressure and interplanetary magnetic field *** work introduces a statistically-based estimation approach based on inverse theory to estimate the spatial distribution of magnetosheath soft X-ray emissivities and,with this,identify the location of the magnetopause over the Sun−Earth *** do so,we simulate the magnetosheath structure using the MHD-based OpenggCM model and generate synthetic soft X-ray images using LEXI’s orbit and attitude *** results show that 3-D estimations using the described statistically-based technique are robust against Poisson-distributed shot noise inherent to soft X-ray ***,our proposed methodology shows that the accuracy of both three-dimensional(3-D)estimation and the magnetopause standoff distance calculation hi

关键词： magnetopause soft X-ray tomography

维普期刊数据库

Single-atom Pt on carbon nanotubes for selective electrocatalysis

在线全文

学校读者我要写书评

暂无评论

Carbon Energy 2024年第1期6卷 63-71页

作者： Samuel S.Hardisty Xiaoqian Lin Anthony R.j.Kucernak david Zitoun Department of Chemistry Bar Ilan Institute of Nanotechnology and Advanced Materials(BINA)Bar Ilan UniversityRamat GanIsrael Department of Chemistry Molecular Science Research HubImperial College LondonLondonUK

Utilizing supported single atoms as catalysts presents an opportunity to reduce the usage of critical raw materials such as platinum,which are essential for electrochemical reactions such as hydrogen oxidation reaction(HOR).Herein,we describe the synthesis of a Pt single electrocatalyst inside single-walled carbon nanotubes(SWCNTs)via a redox *** via electron microscopy,X-ray photoelectron microscopy,and X-ray absorption spectroscopy show the single-atom nature of the *** electrochemical behavior of the sample to hydrogen and oxygen was investigated using the advanced floating electrode technique,which minimizes mass transport limitations and gives a thorough insight into the activity of the *** single-atom samples showed higher HOR activity than state-of-the-art 30%Pt/C while almost no oxygen reduction reaction activity in the proton exchange membrane fuel cell operating *** selective activity toward HOR arose as the main fingerprint of the catalyst confinement in the SWCNTs.

关键词： confinement electrocatalysis hydrogen platinum single atom catalysts

Universal silicon ring resonator for error-free transmission links

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Photonics Research 2024年第4期12卷 701-711页

作者： jUNBO ZHU WEIWEI ZHANg KE LI BHARAT PANT MARTIN EBERT XINgZHAO YAN MEHDI BANAKAR DEHN T.TRAN CALLUM g.LITTLEjOHNS FUWAN gAN gRAHAM REED david j.THOMSON Optoelectronics Research Centre University of SouthamptonSouthampton SO171BJUK National Key Laboratory of Materials for Integrated Circuits Shanghai Institute of Microsystem and Information TechnologyChinese Academy of SciencesShanghai 200050China University of Chinese Academy of Sciences Beijing 100049China Peng Cheng Laboratory ShenzhenChina

We report the design, fabrication, and characterization of a universal silicon PN junction ring resonator for C band error-free communication links operated up to 50 gb/s with co-designed optical modulation and detection performance. The universal p-n junction ring device shows co-designed detection responsivity up to 0.84 A/W, in conjunction with a modulation efficiency of -4 V·mm and>8 d B optical modulation extinction ratio, enabling C band 50 gb/s NRZ communication link with a bit error rate≤3×10^(-12).

关键词： gb/s resonator communication

维普期刊数据库

Evaluation of corneal parameter changes under different accommodative stimuli with Scheimpflug imaging-based tomography

在线全文

学校读者我要写书评

暂无评论

国际眼科杂志 2024年第9期24卷 1357-1366页

作者： Farid j Bedrán-garcía david P Piñero Department of Optics Pharmacology and AnatomyUniversity of AlicanteAlicante 03690Spain

AIM:To evaluate the reliability of measurements of corneal changes with accommodation in healthy eyes using a Scheimpflug imaging-based system and how these measurements distribute in the normal ***:Prospective,non-randomized,comparative study including 27 healthy subjects(54 eyes),including emmetropia(13 eyes),myopia(17 eyes),hyperopia(4 eyes)and astigmatism(20 eyes)*** all cases,a complete eye examination was performed,including the analysis of corneal changes with different accommodative stimuli(+2.00,0.00 and-3.00 D)using the Pentacam AXL *** investigation was structured in 2 phases:repeatability analysis and characterization of accommodation-related corneal changes in healthy ***:In the repeatability analysis,the index of height asymmetry(IHA)showed the greatest variability with the three accommodative stimuli,being the results for the rest of parameters *** group of emmetropes showed significant differences with accommodative changes in the position of maximum keratometry(Kmax;Pgmatism group,significant changes were not only observed in the position of Kmax,but also in minimum corneal thickness(MCT),corneal spherical aberration,and total and low order aberration root mean square(all Pgnificant difference was found in the displacement of the X position of Kmax with+2.00 D and-3.00 D in the myopia group(P=0.033)as well as in changes with+2.00 D and-3.00 D in the magnitude of the position vector of Kmax in the emmetropia group(Pgnificant changes were found between accommodative stimuli in the displacement of coordinates of MCT(P≥0.109).CONCLUSION:The position of Kmax and MCT in healthy corneas can change significantly when presenting different accommodative stimuli using the accommodation mode of the Pentacam system,with different trends in these accommodation-related corneal changes between refractive ***,the consistency of the measurement

关键词： corneal biomechanics keratometry corneal thickness pachymetry corneal aberrations Pentacam accommodation