SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "WFRF:(Archer F) srt2:(2015-2019)"

Sökning: WFRF:(Archer F) > (2015-2019)

  • Resultat 1-24 av 24
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  •  
2.
  • Aartsen, M. G., et al. (författare)
  • Very high-energy gamma-ray follow-up program using neutrino triggers from IceCube
  • 2016
  • Ingår i: Journal of Instrumentation. - 1748-0221. ; 11
  • Tidskriftsartikel (refereegranskat)abstract
    • We describe and report the status of a neutrino-triggered program in IceCube that generates real-time alerts for gamma-ray follow-up observations by atmospheric-Cherenkov telescopes (MAGIC and VERITAS). While IceCube is capable of monitoring the whole sky continuously, high-energy gamma-ray telescopes have restricted fields of view and in general are unlikely to be observing a potential neutrino-flaring source at the time such neutrinos are recorded. The use of neutrino-triggered alerts thus aims at increasing the availability of simultaneous multi-messenger data during potential neutrino flaring activity, which can increase the discovery potential and constrain the phenomenological interpretation of the high-energy emission of selected source classes (e. g. blazars). The requirements of a fast and stable online analysis of potential neutrino signals and its operation are presented, along with first results of the program operating between 14 March 2012 and 31 December 2015.
  •  
3.
  • Abeysekara, A. U., et al. (författare)
  • VERITAS and Fermi-LAT Observations of TeV Gamma-Ray Sources Discovered by HAWC in the 2HWC Catalog
  • 2018
  • Ingår i: Astrophysical Journal. - : Institute of Physics Publishing. - 0004-637X .- 1538-4357. ; 866:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The High Altitude Water Cherenkov (HAWC) collaboration recently published their 2HWC catalog, listing 39 very high energy (VHE; >100 GeV) gamma-ray sources based on 507 days of observation. Among these, 19 sources are not associated with previously known teraelectronvolt (TeV) gamma-ray sources. We have studied 14 of these sources without known counterparts with VERITAS and Fermi-LAT. VERITAS detected weak gamma-ray emission in the 1 TeV-30 TeV band in the region of DA 495, a pulsar wind nebula coinciding with 2HWC J1953+294, confirming the discovery of the source by HAWC. We did not find any counterpart for the selected 14 new HAWC sources from our analysis of Fermi-LAT data for energies higher than 10 GeV. During the search, we detected gigaelectronvolt (GeV) gamma-ray emission coincident with a known TeV pulsar wind nebula, SNR G54.1+0.3 (VER J1930+188), and a 2HWC source, 2HWC J1930+188. The fluxes for isolated, steady sources in the 2HWC catalog are generally in good agreement with those measured by imaging atmospheric Cherenkov telescopes. However, the VERITAS fluxes for SNR G54.1+0.3, DA 495, and TeV J2032+4130 are lower than those measured by HAWC, and several new HAWC sources are not detected by VERITAS. This is likely due to a change in spectral shape, source extension, or the influence of diffuse emission in the source region.
  •  
4.
  • Aartsen, M. G., et al. (författare)
  • Multiwavelength follow-up of a rare IceCube neutrino multiplet
  • 2017
  • Ingår i: Astronomy and Astrophysics. - : EDP SCIENCES S A. - 0004-6361 .- 1432-0746. ; 607
  • Tidskriftsartikel (refereegranskat)abstract
    • On February 17, 2016, the IceCube real-time neutrino search identified, for the first time, three muon neutrino candidates arriving within 100 s of one another, consistent with coming from the same point in the sky. Such a triplet is expected once every 13.7 years as a random coincidence of background events. However, considering the lifetime of the follow-up program the probability of detecting at least one triplet from atmospheric background is 32%. Follow-up observatories were notified in order to search for an electromagnetic counterpart. Observations were obtained by Swift's X-ray telescope, by ASAS-SN, LCO and MASTER at optical wavelengths, and by VERITAS in the very-high-energy gamma-ray regime. Moreover, the Swift BAT serendipitously observed the location 100 s after the first neutrino was detected, and data from the Fermi LAT and HAWC observatory were analyzed. We present details of the neutrino triplet and the follow-up observations. No likely electromagnetic counterpart was detected, and we discuss the implications of these constraints on candidate neutrino sources such as gamma-ray bursts, core-collapse supernovae and active galactic nucleus flares. This study illustrates the potential of and challenges for future follow-up campaigns.
  •  
5.
  •  
6.
  •  
7.
  • Abeysekara, A. U., et al. (författare)
  • A Luminous and Isolated Gamma-Ray Flare from the Blazar B2 1215+30
  • 2017
  • Ingår i: Astrophysical Journal. - : Institute of Physics Publishing (IOPP). - 0004-637X .- 1538-4357. ; 836:2
  • Tidskriftsartikel (refereegranskat)abstract
    • B2 1215+30 is a BL-Lac-type blazar that was first detected at TeV energies by the MAGIC atmospheric Cherenkov telescopes and subsequently confirmed by the Very Energetic Radiation Imaging Telescope Array System (VERITAS) observatory with data collected between 2009 and 2012. In 2014 February 08, VERITAS detected a large-amplitude flare from B2. 1215+30 during routine monitoring observations of the blazar 1ES. 1218+304, located in the same field of view. The TeV flux reached 2.4 times the Crab Nebula flux with a variability timescale of <3.6 hr. Multiwavelength observations with Fermi-LAT, Swift, and the Tuorla Observatory revealed a correlated high GeV flux state and no significant optical counterpart to the flare, with a spectral energy distribution where the gamma-ray luminosity exceeds the synchrotron luminosity. When interpreted in the framework of a onezone leptonic model, the observed emission implies a high degree of beaming, with Doppler factor delta > 10, and an electron population with spectral index p < 2.3.
  •  
8.
  • Ferrara, R., et al. (författare)
  • Autism Spectrum Disorder and intact executive functioning
  • 2016
  • Ingår i: Clinica Terapeutica. - 0009-9074. ; 167:5, s. 96-101
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Earliest notions concerning autism (Autism Spectrum Disorders, ASD) describe the disturbance in executive functioning. Despite altered definition, executive functioning, expressed as higher cognitive skills required complex behaviors linked to the prefrontal cortex, are defective in autism. Specific difficulties in children presenting autism or verbal disabilities at executive functioning levels have been identified. Nevertheless, the developmental deficit of executive functioning in autism is highly diversified with huge individual variation and may even be absent. The aim of the present study to examine the current standing of intact executive functioning intact in ASD. Results: Analysis of ASD populations, whether high-functioning, Asperger's or autism Broad Phenotype, studied over a range of executive functions including response inhibition, planning, cognitive flexibility, cognitive inhibition, and alerting networks indicates an absence of damage/impairment compared to the typically-developed normal control subjects. Conclusions: These findings of intact executive functioning in ASD subjects provide a strong foundation on which to construct applications for growth environments and the rehabilitation of autistic subjects.
  •  
9.
  • Ippoliti, F., et al. (författare)
  • Work-related Stress, over-nutrition and cognitive disability
  • 2017
  • Ingår i: Clinica Terapeutica. - 0009-9074. ; 168:1, s. 42-47
  • Forskningsöversikt (refereegranskat)abstract
    • Work-related stress may exert a negative impact on a variety of physical and psychological attributes relating to the health of employees and work organizations. Several studies conducted in Italy have shown that workers and employees who express less satisfaction show increased symptoms of obesity and cognitive disability. The latest evidence underlines the pathogenic relationship between stress and neurological disease through inflammatory neuro- immune activation. The aim of this review was to describe the relationship between workplace stress and adverse changes in lifestyle that develop into obesity, neuroinflammation and cognitive dysfunction. The molecular mechanisms involved and guidelines for the prevention of these trends are discussed briefly. © Società Editrice Universo (SEU).
  •  
10.
  • Raghavan, Maanasa, et al. (författare)
  • Genomic evidence for the Pleistocene and recent population history of Native Americans
  • 2015
  • Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 349:6250
  • Tidskriftsartikel (refereegranskat)abstract
    • Howand when the Americas were populated remains contentious. Using ancient and modern genome-wide data, we found that the ancestors of all present-day Native Americans, including Athabascans and Amerindians, entered the Americas as a single migration wave from Siberia no earlier than 23 thousand years ago (ka) and after no more than an 8000-year isolation period in Beringia. After their arrival to the Americas, ancestral Native Americans diversified into two basal genetic branches around 13 ka, one that is now dispersed across North and South America and the other restricted to North America. Subsequent gene flow resulted in some Native Americans sharing ancestry with present-day East Asians (including Siberians) and, more distantly, Australo-Melanesians. Putative "Paleoamerican" relict populations, including the historical Mexican Pericues and South American Fuego-Patagonians, are not directly related to modern Australo-Melanesians as suggested by the Paleoamerican Model.
  •  
11.
  • Waszak, S. M., et al. (författare)
  • Spectrum and prevalence of genetic predisposition in medulloblastoma: a retrospective genetic study and prospective validation in a clinical trial cohort
  • 2018
  • Ingår i: Lancet Oncology. - : Elsevier BV. - 1470-2045. ; 19:6, s. 785-798
  • Tidskriftsartikel (refereegranskat)abstract
    • Background Medulloblastoma is associated with rare hereditary cancer predisposition syndromes; however, consensus medulloblastoma predisposition genes have not been defined and screening guidelines for genetic counselling and testing for paediatric patients are not available. We aimed to assess and define these genes to provide evidence for future screening guidelines. Methods In this international, multicentre study, we analysed patients with medulloblastoma from retrospective cohorts (International Cancer Genome Consortium [ICGC] PedBrain, Medulloblastoma Advanced Genomics International Consortium [MAGIC], and the CEFALO series) and from prospective cohorts from four clinical studies (SJMB03, SJMB12, SJYC07, and I-HIT-MED). Whole-genome sequences and exome sequences from blood and tumour samples were analysed for rare damaging germline mutations in cancer predisposition genes. DNA methylation profiling was done to determine consensus molecular subgroups: WNT (MBWNT), SHH (MBSHH), group 3 (MBGroup3), and group 4 (MBGroup4). Medulloblastoma predisposition genes were predicted on the basis of rare variant burden tests against controls without a cancer diagnosis from the Exome Aggregation Consortium (ExAC). Previously defined somatic mutational signatures were used to further classify medulloblastoma genomes into two groups, a clock-like group (signatures 1 and 5) and a homologous recombination repair deficiency-like group (signatures 3 and 8), and chromothripsis was investigated using previously established criteria. Progression-free survival and overall survival were modelled for patients with a genetic predisposition to medulloblastoma. Findings We included a total of 1022 patients with medulloblastoma from the retrospective cohorts (n=673) and the four prospective studies (n=349), from whom blood samples (n=1022) and tumour samples (n=800) were analysed for germline mutations in 110 cancer predisposition genes. In our rare variant burden analysis, we compared these against 53 105 sequenced controls from ExAC and identified APC, BRCA2, PALB2, PTCH1, SUFU, and TP53 as consensus medulloblastoma predisposition genes according to our rare variant burden analysis and estimated that germline mutations accounted for 6% of medulloblastoma diagnoses in the retrospective cohort. The prevalence of genetic predispositions differed between molecular subgroups in the retrospective cohort and was highest for patients in the MBSHH subgroup (20% in the retrospective cohort). These estimates were replicated in the prospective clinical cohort (germline mutations accounted for 5% of medulloblastoma diagnoses, with the highest prevalence [14%] in the MBSHH subgroup). Patients with germline APC mutations developed MBWNT and accounted for most (five [71%] of seven) cases of MBWNT that had no somatic CTNNB1 exon 3 mutations. Patients with germline mutations in SUFU and PTCH1 mostly developed infant MBSHH. Germline TP53 mutations presented only in childhood patients in the MBSHH subgroup and explained more than half (eight [57%] of 14) of all chromothripsis events in this subgroup. Germline mutations in PALB2 and BRCA2 were observed across the MBSHH, MBGroup3, and MBGroup4 molecular subgroups and were associated with mutational signatures typical of homologous recombination repair deficiency. In patients with a genetic predisposition to medulloblastoma, 5-year progression-free survival was 52% (95% CI 4069) and 5-year overall survival was 65% (95% CI 5281); these survival estimates differed significantly across patients with germline mutations in different medulloblastoma predisposition genes. Interpretation Genetic counselling and testing should be used as a standard-of-care procedure in patients with MBWNT and MBSHH because these patients have the highest prevalence of damaging germline mutations in known cancer predisposition genes. We propose criteria for routine genetic screening for patients with medulloblastoma based on clinical and molecular tumour characteristics. Copyright (c) 2018 The Author(s). Published by Elsevier Ltd.
  •  
12.
  • Archer, Trevor, 1949, et al. (författare)
  • Cognitive benefits of exercise intervention
  • 2016
  • Ingår i: Clinica Terapeutica. - 0009-9074 .- 1972-6007. ; 167:6, s. 180-185
  • Tidskriftsartikel (refereegranskat)abstract
    • © Società Editrice Universo (SEU).Exercise, as a potent epigenetic regulator, implies the potential to counteract pathophysiological processes and alterations in most cardiovascular/respiratory cells and tissues not withstanding a paucity of understanding the underlying molecular mechanisms and doseresponse relationships. In the present account, the assets accruing from physical exercise and its influence upon executive functioning are examined. Under conditions of neuropsychiatric and neurologic ill-health, age-related deterioration of functional and biomarker indicators during healthy and disordered trajectories, neuroimmune and affective unbalance, and epigenetic pressures, exercise offers a large harvest of augmentations in health and well-being. Both animal models and human studies support the premise of manifest gains from regular exercise within several domains, besides cognitive function and mood, notably as the agency of a noninvasive, readily available therapeutic intervention.
  •  
13.
  •  
14.
  • Freissinet, C., et al. (författare)
  • Organic molecules in the Sheepbed Mudstone, Gale Crater, Mars
  • 2015
  • Ingår i: Journal of Geophysical Research - Planets. - 2169-9097 .- 2169-9100. ; 120:3, s. 495-514
  • Tidskriftsartikel (refereegranskat)abstract
    • The Sample Analysis at Mars (SAM) instrument [Mahaffy et al., 2012] onboard the Mars Science Laboratory (MSL) Curiosity rover is designed to conduct inorganic and organic chemical analyses of the atmosphere and the surface regolith and rocks to help evaluate the past and present habitability potential of Mars at Gale Crater [Grotzinger et al., 2012]. Central to this task is the development of an inventory of any organic molecules present to elucidate processes associated with their origin, diagenesis, concentration and long-term preservation. This will guide the future search for biosignatures [Summons et al., 2011]. Here we report the definitive identification of chlorobenzene (150–300 parts per billion by weight (ppbw)) and C2 to C4 dichloroalkanes (up to 70 ppbw) with the SAM gas chromatograph mass spectrometer (GCMS), and detection of chlorobenzene in the direct evolved gas analysis (EGA) mode, in multiple portions of the fines from the Cumberland drill hole in the Sheepbed mudstone at Yellowknife Bay. When combined with GCMS and EGA data from multiple scooped and drilled samples, blank runs and supporting laboratory analog studies, the elevated levels of chlorobenzene and the dichloroalkanes cannot be solely explained by instrument background sources known to be present in SAM. We conclude that these chlorinated hydrocarbons are the reaction products of martian chlorine and organic carbon derived from martian sources (e.g. igneous, hydrothermal, atmospheric, or biological) or exogenous sources such as meteorites, comets or interplanetary dust particles.
  •  
15.
  • Hietala, H., et al. (författare)
  • In Situ Observations of a Magnetosheath High-Speed Jet Triggering Magnetopause Reconnection
  • 2018
  • Ingår i: Geophysical Research Letters. - : American Geophysical Union (AGU). - 0094-8276 .- 1944-8007. ; 45:4, s. 1732-1740
  • Tidskriftsartikel (refereegranskat)abstract
    • Magnetosheath high-speed jets-localized dynamic pressure enhancements typically of similar to 1 Earth radius in size-impact the dayside magnetopause several times per hour. Here we present the first in situ measurements suggesting that such an impact triggered magnetopause reconnection. We use observations from the five Time History of Events and Macroscale Interactions during Substorms spacecraft in a string-of-pearls configuration on 7 August 2007. The spacecraft recorded magnetopause in-and-out motion during an impact of a magnetosheath jet (V-N similar to -300km/s along the magnetopause normal direction). There was no evidence for reconnection for the preimpact crossing, yet three probes observed reconnection after the impact. We infer that the jet impact compressed the originally thick (60-70 d(i)), high magnetic shear (140-160 degrees magnetopause until it was thin enough for reconnection to occur. Magnetosheath high-speed jets could therefore act as a driver for bursty dayside reconnection.
  •  
16.
  • Massoni, F., et al. (författare)
  • Psychopathology and neoplastic disease: Medico-social and medico-legal considerations
  • 2017
  • Ingår i: Clinica Terapeutica. - 0009-9074. ; 168:1, s. 48-53
  • Forskningsöversikt (refereegranskat)abstract
    • The cognitive disability associated with stress in patients presenting cancer disease may exert a significant impact on the psychological health of the individual and even deteriorate the clinical diagnosis. The present study consists of a review of the available literature and an analysis of the association between psychopathologic disease and cancer by selecting useful contributions to the medicosocial discussion of the topic. Interesting considerations have emerged on the epidemiology and pathogenesis of the association between psychopathology and cancer that initiated possibilities towards a greater accuracy in the assessment of the patient that is not only limited to oncologic problems and outcomes. © Società Editrice Universo (SEU).
  •  
17.
  • Navarro‐González, Rafael, et al. (författare)
  • Abiotic Input of Fixed Nitrogen by Bolide Impacts to Gale Crater During the Hesperian : Insights From the Mars Science Laboratory
  • 2019
  • Ingår i: Journal of Geophysical Research - Planets. - : John Wiley & Sons. - 2169-9097 .- 2169-9100. ; 124:1, s. 94-113
  • Tidskriftsartikel (refereegranskat)abstract
    • Molecular hydrogen (H2) from volcanic emissions is suggested to warm the Martian surface when carbon dioxide (CO2) levels dropped from the Noachian (4100 to 3700 Myr) to the Hesperian (3700 to 3000 Myr). Its presence is expected to shift the conversion of molecular nitrogen (N2) into different forms of fixed nitrogen (N). Here we present experimental data and theoretical calculations that investigate the efficiency of nitrogen fixation by bolide impacts in CO2‐N2 atmospheres with or without H2. Surprisingly, nitric oxide (NO) was produced more efficiently in 20% H2 in spite of being a reducing agent and not likely to increase the rate of nitrogen oxidation. Nevertheless, its presence led to a faster cooling of the shock wave raising the freeze‐out temperature of NO resulting in an enhanced yield. We estimate that the nitrogen fixation rate by bolide impacts varied from 7 × 10−4 to 2 × 10−3 g N·Myr−1·cm−2 and could imply fluvial concentration to explain the nitrogen (1.4 ± 0.7 g N·Myr−1·cm−2) detected as nitrite (NO2−) and nitrate (NO3−) by Curiosity at Yellowknife Bay. One possible explanation is that the nitrogen detected in the lacustrine sediments at Gale was deposited entirely on the crater's surface and was subsequently dissolved and transported by superficial and ground waters to the lake during favorable wet climatic conditions. The nitrogen content sharply decreases in younger sediments of the Murray formation suggesting a decline of H2 in the atmosphere and the rise of oxidizing conditions causing a shortage in the supply to putative microbial life.
  •  
18.
  • Onofri, E., et al. (författare)
  • Effect of cognitive fluctuation on handwriting in Alzheimer's patient: A case study
  • 2015
  • Ingår i: Acta Medica Mediterranea. - 0393-6384. ; 31:3, s. 751-755
  • Tidskriftsartikel (refereegranskat)abstract
    • Introduction: The older population is rapidly growing in the European states and across the globe; and in aging we notice a cognitive declines, a decrease in memory and decision-making abilities. Characteristics of the cognitive fluctuations occur infrequently in the elderly, but they are present in patients with dementia. Fluctuating cognition and abilities have been described as periods of behavioral and thought confusion, inattention, and incoherent speech alternating with episodes of lucidity. It is common in Dementia with Lewy bodies (DLB), however, the role of fluctuations in Alzheimer 's disease (AD) has not been much considered. Case presentation: The present study examines the relationship between cognitive status and handwritten scripts, presented as 'letter-writing' in AD patient, as oscillations of the symptoms phase. Discussion: We present evidence that the deficits of attention and its fluctuations and the cognitive impairment are related with the handwritten expression.
  •  
19.
  • Palmroth, M., et al. (författare)
  • Magnetosheath jet properties and evolution as determined by a global hybrid-Vlasov simulation
  • 2018
  • Ingår i: Annales Geophysicae. - : Copernicus GmbH. - 0992-7689 .- 1432-0576. ; 36:5, s. 1171-1182
  • Tidskriftsartikel (refereegranskat)abstract
    • We use a global hybrid-Vlasov simulation for the magnetosphere, Vlasiator, to investigate magnetosheath high-speed jets. Unlike many other hybrid-kinetic simulations, Vlasiator includes an unscaled geomagnetic dipole, indicating that the simulation spatial and temporal dimensions can be given in SI units without scaling. Thus, for the first time, this allows investigating the magnetosheath jet properties and comparing them directly with the observed jets within the Earth's magnetosheath. In the run shown in this paper, the interplanetary magnetic field (IMF) cone angle is 30°, and a foreshock develops upstream of the quasi-parallel magnetosheath. We visually detect a structure with high dynamic pressure propagating from the bow shock through the magnetosheath. The structure is confirmed as a jet using three different criteria, which have been adopted in previous observational studies. We compare these criteria against the simulation results. We find that the magnetosheath jet is an elongated structure extending earthward from the bow shock by ∼ 2.6 RE, while its size perpendicular to the direction of propagation is ∼ 0.5R/E. We also investigate the jet evolution and find that the jet originates due to the interaction of the bow shock with a high-dynamic-pressure structure that reproduces observational features associated with a short, large-amplitude magnetic structure (SLAMS). The simulation shows that magnetosheath jets can develop also under steady IMF, as inferred by observational studies. To our knowledge, this paper therefore shows the first global kinetic simulation of a magnetosheath jet, which is in accordance with three observational jet criteria and is caused by a SLAMS advecting towards the bow shock. 
  •  
20.
  • Pavlova, Elena V., et al. (författare)
  • Inhibition of UDP-glucosylceramide synthase in mice prevents Gaucher disease-associated B-cell malignancy
  • 2015
  • Ingår i: Journal of Pathology. - : Wiley. - 0022-3417. ; 235:1, s. 113-124
  • Tidskriftsartikel (refereegranskat)abstract
    • Clonal B-cell proliferation is a frequent manifestation of Gaucher disease-a sphingolipidosis associated with a high risk of multiple myeloma and non-Hodgkin lymphoma. Gaucher disease is caused by genetic deficiency of acid -glucosidase, the natural substrates of which (-d-glucosylceramide and -d-glucosylsphingosine) accumulate, principally in macrophages. Mice with inducible deficiency of -glucosidase [Gba(tm1Karl/tm1Karl)Tg(MX1-cre)1Cgn/0] serve as an authentic model of human Gaucher disease; we have recently reported clonal B-cell proliferation accompanied by monoclonal serum paraproteins and cognate tumours in these animals. To explore the relationship between B-cell malignancy and the biochemical defect, we treated Gaucher mice with eliglustat tartrate (GENZ 112638), a potent and selective inhibitor of the first committed step in glycosphingolipid biosynthesis. Twenty-two Gaucher mice received 300mg/kg of GENZ 112638 daily for 3-10 months from 6 weeks of age. Plasma concentrations of -d-glucosylceramide and the unacylated glycosphingolipid, -d-glucosylsphingosine, declined. After administration of GENZ 112638 to Gaucher mice for 3-10 months, serum paraproteins were not detected and there was a striking reduction in the malignant lymphoproliferation: neither lymphomas nor plasmacytomas were found in animals that had received the investigational agent. In contrast, 14 out of 60 Gaucher mice without GENZ 112638 treatment developed these tumours; monoclonal paraproteins were detected in plasma from 18 of the 44 age-matched mice with Gaucher disease that had not received GENZ 112638. Long-term inhibition of glycosphingolipid biosynthesis suppresses the development of spontaneous B-cell lymphoma and myeloma in Gaucher mice. Copyright (c) 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
  •  
21.
  • Plaschke, F., et al. (författare)
  • Magnetosheath High-Speed Jets : Internal Structure and InteractionWith Ambient Plasma
  • 2017
  • Ingår i: Journal of Geophysical Research - Space Physics. - : AMER GEOPHYSICAL UNION. - 2169-9380 .- 2169-9402. ; 122:10, s. 10157-10175
  • Tidskriftsartikel (refereegranskat)abstract
    • For the first time, we have studied the rich internal structure of a magnetosheath high-speed jet. Measurements by the Magnetospheric Multiscale (MMS) spacecraft reveal large-amplitude density, temperature, and magnetic field variations inside the jet. The propagation velocity and normal direction of planar magnetic field structures (i.e., current sheets and waves) are investigated via four-spacecraft timing. We find structures to mainly convect with the jet plasma. There are indications of the presence of a tangential discontinuity. At other times, there are small cross-structure flows. Where this is the case, current sheets and waves overtake the plasma in the jet's core region; ahead and behind that core region, along the jet's path, current sheets are overtaken by the plasma; that is, they move in opposite direction to the jet in the plasma rest frame. Jet structures are found to be mainly thermal and magnetic pressure balance structures, notwithstanding that the dynamic pressure dominates by far. Although the jet is supermagnetosonic in the Earth's frame of reference, it is submagnetosonic with respect to the plasma ahead. Consequently, we find no fast shock. Instead, we find some evidence for (a series of) jets pushing ambient plasma out of their way, thereby stirring the magnetosheath and causing anomalous sunward flows in the subsolar magnetosheath. Furthermore, we find that jets modify the magnetic field in the magnetosheath, aligning it with their propagation direction.
  •  
22.
  •  
23.
  •  
24.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-24 av 24

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy