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  • 1
    Online Resource
    Online Resource
    Coronal Heating as Determined by the Solar Flare Frequency Distribution Obtained by Aggregating Case Studies
    American Astronomical Society ; 2023
    In:  The Astrophysical Journal Vol. 948, No. 2 ( 2023-05-01), p. 71-
    Details
    In: The Astrophysical Journal, American Astronomical Society, Vol. 948, No. 2 ( 2023-05-01), p. 71-
    Abstract: Flare frequency distributions represent a key approach to addressing one of the largest problems in solar and stellar physics: determining the mechanism that counterintuitively heats coronae to temperatures that are orders of magnitude hotter than the corresponding photospheres. It is widely accepted that the magnetic field is responsible for the heating, but there are two competing mechanisms that could explain it: nanoflares or Alfvén waves. To date, neither can be directly observed. Nanoflares are, by definition, extremely small, but their aggregate energy release could represent a substantial heating mechanism, presuming they are sufficiently abundant. One way to test this presumption is via the flare frequency distribution, which describes how often flares of various energies occur. If the slope of the power law fitting the flare frequency distribution is above a critical threshold, α = 2 as established in prior literature, then there should be a sufficient abundance of nanoflares to explain coronal heating. We performed 〉 600 case studies of solar flares, made possible by an unprecedented number of data analysts via three semesters of an undergraduate physics laboratory course. This allowed us to include two crucial, but nontrivial, analysis methods: preflare baseline subtraction and computation of the flare energy, which requires determining flare start and stop times. We aggregated the results of these analyses into a statistical study to determine that α = 1.63 ± 0.03. This is below the critical threshold, suggesting that Alfvén waves are an important driver of coronal heating.
    Type of Medium: Online Resource
    ISSN: 0004-637X , 1538-4357
    URL: Article
    DOI: 10.3847/1538-4357/accc89
    RVK:
    UA 1000
    Language: Unknown
    Publisher: American Astronomical Society
    Publication Date: 2023
    detail.hit.zdb_id: 2207648-7
    detail.hit.zdb_id: 1473835-1
    SSG: 16,12
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  • 2
    Online Resource
    Online Resource
    Elektroanalyse
    Springer Science and Business Media LLC ; 1931
    In:  Zeitschrift für Analytische Chemie Vol. 83, No. 3-4 ( 1931-3), p. 124-143
    Details
    In: Zeitschrift für Analytische Chemie, Springer Science and Business Media LLC, Vol. 83, No. 3-4 ( 1931-3), p. 124-143
    Type of Medium: Online Resource
    ISSN: 1618-2642 , 1618-2650
    URL: Article
    DOI: 10.1007/BF01361035
    RVK:
    VA 4300
    Language: German
    Publisher: Springer Science and Business Media LLC
    Publication Date: 1931
    detail.hit.zdb_id: 1459122-4
    detail.hit.zdb_id: 2071767-2
    SSG: 12
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  • 3
    Online Resource
    Online Resource
    A muon-track reconstruction exploiting stochastic losses for large-scale Cherenkov detectors
    IOP Publishing ; 2021
    In:  Journal of Instrumentation Vol. 16, No. 08 ( 2021-08-01), p. P08034-
    Details
    In: Journal of Instrumentation, IOP Publishing, Vol. 16, No. 08 ( 2021-08-01), p. P08034-
    Abstract: IceCube is a cubic-kilometer Cherenkov telescope operating at the South Pole. The main goal of IceCube is the detection of astrophysical neutrinos and the identification of their sources. High-energy muon neutrinos are observed via the secondary muons produced in charge current interactions with nuclei in the ice. Currently, the best performing muon track directional reconstruction is based on a maximum likelihood method using the arrival time distribution of Cherenkov photons registered by the experiment's photomultipliers. A known systematic shortcoming of the prevailing method is to assume a continuous energy loss along the muon track. However at energies 〉 1 TeV the light yield from muons is dominated by stochastic showers. This paper discusses a generalized ansatz where the expected arrival time distribution is parametrized by a stochastic muon energy loss pattern. This more realistic parametrization of the loss profile leads to an improvement of the muon angular resolution of up to 20% for through-going tracks and up to a factor 2 for starting tracks over existing algorithms. Additionally, the procedure to estimate the directional reconstruction uncertainty has been improved to be more robust against numerical errors.
    Type of Medium: Online Resource
    ISSN: 1748-0221
    URL: Article
    DOI: 10.1088/1748-0221/16/08/P08034
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2021
    detail.hit.zdb_id: 2235672-1
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  • 4
    Online Resource
    Online Resource
    Graph Neural Networks for low-energy event classification & reconstruction in IceCube
    IOP Publishing ; 2022
    In:  Journal of Instrumentation Vol. 17, No. 11 ( 2022-11-01), p. P11003-
    Details
    In: Journal of Instrumentation, IOP Publishing, Vol. 17, No. 11 ( 2022-11-01), p. P11003-
    Abstract: IceCube, a cubic-kilometer array of optical sensors built to detect atmospheric and astrophysical neutrinos between 1 GeV and 1 PeV, is deployed 1.45 km to 2.45 km below the surface of the ice sheet at the South Pole. The classification and reconstruction of events from the in-ice detectors play a central role in the analysis of data from IceCube. Reconstructing and classifying events is a challenge due to the irregular detector geometry, inhomogeneous scattering and absorption of light in the ice and, below 100 GeV, the relatively low number of signal photons produced per event. To address this challenge, it is possible to represent IceCube events as point cloud graphs and use a Graph Neural Network (GNN) as the classification and reconstruction method. The GNN is capable of distinguishing neutrino events from cosmic-ray backgrounds, classifying different neutrino event types, and reconstructing the deposited energy, direction and interaction vertex. Based on simulation, we provide a comparison in the 1 GeV–100 GeV energy range to the current state-of-the-art maximum likelihood techniques used in current IceCube analyses, including the effects of known systematic uncertainties. For neutrino event classification, the GNN increases the signal efficiency by 18% at a fixed background rate, compared to current IceCube methods. Alternatively, the GNN offers a reduction of the background (i.e. false positive) rate by over a factor 8 (to below half a percent) at a fixed signal efficiency. For the reconstruction of energy, direction, and interaction vertex, the resolution improves by an average of 13%–20% compared to current maximum likelihood techniques in the energy range of 1 GeV–30 GeV. The GNN, when run on a GPU, is capable of processing IceCube events at a rate nearly double of the median IceCube trigger rate of 2.7 kHz, which opens the possibility of using low energy neutrinos in online searches for transient events.
    Type of Medium: Online Resource
    ISSN: 1748-0221
    URL: Article
    DOI: 10.1088/1748-0221/17/11/P11003
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2022
    detail.hit.zdb_id: 2235672-1
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  • 5
    Online Resource
    Online Resource
    D-Egg: a dual PMT optical module for IceCube
    IOP Publishing ; 2023
    In:  Journal of Instrumentation Vol. 18, No. 04 ( 2023-04-01), p. P04014-
    Details
    In: Journal of Instrumentation, IOP Publishing, Vol. 18, No. 04 ( 2023-04-01), p. P04014-
    Abstract: The D-Egg, an acronym for “Dual optical sensors in an Ellipsoid Glass for Gen2,” is one of the optical modules designed for future extensions of the IceCube experiment at the South Pole. The D-Egg has an elongated-sphere shape to maximize the photon-sensitive effective area while maintaining a narrow diameter to reduce the cost and the time needed for drilling of the deployment holes in the glacial ice for the optical modules at depths up to 2700 m. The D-Egg design is utilized for the IceCube Upgrade, the next stage of the IceCube project also known as IceCube-Gen2 Phase 1, where nearly half of the optical sensors to be deployed are D-Eggs. With two 8-inch high-quantum efficiency photomultiplier tubes (PMTs) per module, D-Eggs offer an increased effective area while retaining the successful design of the IceCube digital optical module (DOM). The convolution of the wavelength-dependent effective area and the Cherenkov emission spectrum provides an effective photodetection sensitivity that is 2.8 times larger than that of IceCube DOMs. The signal of each of the two PMTs is digitized using ultra-low-power 14-bit analog-to-digital converters with a sampling frequency of 240 MSPS, enabling a flexible event triggering, as well as seamless and lossless event recording of single-photon signals to multi-photons exceeding 200 photoelectrons within 10 ns. Mass production of D-Eggs has been completed, with 277 out of the 310 D-Eggs produced to be used in the IceCube Upgrade. In this paper, we report the design of the D-Eggs, as well as the sensitivity and the single to multi-photon detection performance of mass-produced D-Eggs measured in a laboratory using the built-in data acquisition system in each D-Egg optical sensor module.
    Type of Medium: Online Resource
    ISSN: 1748-0221
    URL: Article
    DOI: 10.1088/1748-0221/18/04/P04014
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2023
    detail.hit.zdb_id: 2235672-1
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  • 6
    Online Resource
    Online Resource
    GDF15 Promotes the Osteogenic Cell Fate of Periodontal Ligament Fibroblasts, thus Affecting Their Mechanobiological Response
    MDPI AG ; 2023
    In:  International Journal of Molecular Sciences Vol. 24, No. 12 ( 2023-06-11), p. 10011-
    Details
    In: International Journal of Molecular Sciences, MDPI AG, Vol. 24, No. 12 ( 2023-06-11), p. 10011-
    Abstract: Periodontal ligament fibroblasts (PdLFs) exert important functions in oral tissue and bone remodeling following mechanical forces, which are specifically applied during orthodontic tooth movement (OTM). Located between the teeth and the alveolar bone, mechanical stress activates the mechanomodulatory functions of PdLFs including regulating local inflammation and activating further bone-remodeling cells. Previous studies suggested growth differentiation factor 15 (GDF15) as an important pro-inflammatory regulator during the PdLF mechanoresponse. GDF15 exerts its effects through both intracrine signaling and receptor binding, possibly even in an autocrine manner. The extent to which PdLFs are susceptible to extracellular GDF15 has not yet been investigated. Thus, our study aims to examine the influence of GDF15 exposure on the cellular properties of PdLFs and their mechanoresponse, which seems particularly relevant regarding disease- and aging-associated elevated GDF15 serum levels. Therefore, in addition to investigating potential GDF15 receptors, we analyzed its impact on the proliferation, survival, senescence, and differentiation of human PdLFs, demonstrating a pro-osteogenic effect upon long-term stimulation. Furthermore, we observed altered force-related inflammation and impaired osteoclast differentiation. Overall, our data suggest a major impact of extracellular GDF15 on PdLF differentiation and their mechanoresponse.
    Type of Medium: Online Resource
    ISSN: 1422-0067
    URL: Article
    DOI: 10.3390/ijms241210011
    Language: English
    Publisher: MDPI AG
    Publication Date: 2023
    detail.hit.zdb_id: 2019364-6
    SSG: 12
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  • 7
    Online Resource
    Online Resource
    Synthesis and Structural Characterization of Copper(I) and Copper(II) Complexes with an Ambivalent Phenanthroline-Type Ligand
    CSIRO Publishing ; 1997
    In:  Australian Journal of Chemistry Vol. 50, No. 10 ( 1997), p. 951-
    Details
    In: Australian Journal of Chemistry, CSIRO Publishing, Vol. 50, No. 10 ( 1997), p. 951-
    Abstract: The new phenanthroline ligand 2-(p-methoxyphenyl)-9-(5′-methylpyridin-2′-yl)-1,10-phenanthroline L has been synthesized and shown to form four-coordinate CuI(L)2 (1) and six-coordinate CuII(L)2 (2) complexes. Their structures have been determined by X-ray crystallography: (1) C50H38CuN6O2.BF4, triclinic, space group P -1, a12·924(3), b 14·567(4), c 12·649(3) Å , α 105·57(2), β 107·68(2), γ 104·00(2)°; (2) C50H38CuN6O2.2PF6, monoclinic, space group P 21/c, a 17·701(5), b 19·285(5), c 14·93(4) Å, β 98·20(2)°. In solution, cyclic voltammetry measurements indicate for the copper(I) and copper(II) complexes a very fast rearrangement of the pyridine substituent with the change of the oxidation state. Surprisingly, the X-ray data show two different coordination modes for the ligand around the copper(I) ion, the 1,10-phenanthroline nucleus being either mono- or bi-dentate. In solution, since the 1H n.m.r. spectra obtained even at several temperatures display only one set of signals, it is proposed that a fast equilibrium takes place between two coordination modes of the phenanthroline
    Type of Medium: Online Resource
    ISSN: 0004-9425
    URL: Article
    DOI: 10.1071/C97106
    RVK:
    VA 2470
    Language: English
    Publisher: CSIRO Publishing
    Publication Date: 1997
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  • 8
    Online Resource
    Online Resource
    Searches for connections between dark matter and high-energy neutrinos with IceCube
    IOP Publishing ; 2023
    In:  Journal of Cosmology and Astroparticle Physics Vol. 2023, No. 10 ( 2023-10-01), p. 003-
    Details
    In: Journal of Cosmology and Astroparticle Physics, IOP Publishing, Vol. 2023, No. 10 ( 2023-10-01), p. 003-
    Abstract: In this work, we present the results of searches for signatures of dark matter decay or annihilation into Standard Model particles, and secret neutrino interactions with dark matter. Neutrinos could be produced in the decay or annihilation of galactic or extragalactic dark mat ter. Additionally, if an interaction between dark matter and neutrinos exists then dark matter will interact with extragalactic neutrinos. In particular galactic dark matter will induce an anisotropy in the neutrino sky if this interaction is present. We use seven and a half years of the High-Energy Starting Event (HESE) sample data, which measures neutrinos in the energy range of approximately 60 TeV to 10 PeV, to study these phenomena. This all-sky event selection is dominated by extragalactic neutrinos. For dark matter of ∼ 1 PeV in mass, we constrain the velocity-averaged annihilation cross section to be smaller than 10 -23 cm 3 /s for the exclusive μ + μ - channel and 10 -22 cm 3 /s for the bb̅ channel. For the same mass, we constrain the lifetime of dark matter to be larger than 10 28 s for all channels studied, except for decaying exclusively to bb̅ where it is bounded to be larger than 10 27 s. Finally, we also search for evidence of astrophysical neutrinos scattering on galactic dark matter in two scenarios. For fermionic dark matter with a vector mediator, we constrain the dimensionless coupling associated with this interaction to be less than 0.1 for dark matter mass of 0.1 GeV and a mediator mass of 10 -4 GeV. In the case of scalar dark matter with a fermionic mediator, we constrain the coupling to be less than 0.1 for dark matter and mediator masses below 1 MeV.
    Type of Medium: Online Resource
    ISSN: 1475-7516
    URL: Article
    DOI: 10.1088/1475-7516/2023/10/003
    Language: Unknown
    Publisher: IOP Publishing
    Publication Date: 2023
    detail.hit.zdb_id: 2104147-7
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  • 9
    Online Resource
    Online Resource
    The Cancer Chemotherapy Drug Etoposide (VP-16) Induces Proinflammatory Cytokine Production and Sickness Behavior–like Symptoms in a Mouse Model of Cancer Chemotherapy–Related Symptoms
    SAGE Publications ; 2006
    In:  Biological Research For Nursing Vol. 8, No. 2 ( 2006-10), p. 157-169
    Details
    In: Biological Research For Nursing, SAGE Publications, Vol. 8, No. 2 ( 2006-10), p. 157-169
    Abstract: Cancer chemotherapy–related symptoms such as fatigue, malaise, loss of interest in social activities, difficulty concentrating, and changes in sleep patterns can lead to treatment delays, dose reductions, or termination and have a profound effect on the physical, psychosocial, and economic aspects of quality of life. Clinicians have long suspected that these symptoms are similar to those associated with “sickness behavior,” which is triggered by the production of the inflammatory cytokines IL-1β, TNF-α, and IL-6 by macrophages and other cells of the innate immune system in response to immune challenge. The p38 mitogen-activated protein kinase (p38 MAPK) plays a central role in the production of these cytokines and consequently the induction of sickness behavior. Several cancer chemotherapy drugs have been shown to activate p38 MAPK, but whether these drugs can also induce the production of inflammatory cytokines to cause sickness behavior is unknown. The aim of this study was to determine whether the cancer chemotherapy drug etoposide (VP-16), which is known to activate p38 MAPK, could induce inflammatory cytokine production by murine macrophages and sickness-like behaviors when injected into mice. VP-16 activated p38 MAPK and induced IL-6 production in murine macrophages in a p38 MAPK– dependent manner. VP-16 administration rapidly increased serum levels of IL-6 in healthy mice and induced sickness-like behaviors as evidenced by a decrease in food intake, body weight, hemoglobin level, and voluntary wheel-running activity. These findings support the idea that the induction of IL-1β, TNF-α, and IL-6 by cancer chemotherapy drugs underlies the fatigue and associated symptoms experienced by people undergoing cancer chemotherapy.
    Type of Medium: Online Resource
    ISSN: 1099-8004 , 1552-4175
    URL: Article
    DOI: 10.1177/1099800406290932
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2006
    detail.hit.zdb_id: 2070503-7
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  • 10
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    Precision muon reconstruction in Double Chooz
    Elsevier BV ; 2014
    In:  Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment Vol. 764 ( 2014-11), p. 330-339
    Details
    In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Elsevier BV, Vol. 764 ( 2014-11), p. 330-339
    Type of Medium: Online Resource
    ISSN: 0168-9002
    URL: Article
    DOI: 10.1016/j.nima.2014.07.058
    RVK:
    UA 5680.A
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2014
    detail.hit.zdb_id: 1466532-3
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