| 1. |
- Abbasi, R., et al.
(author)
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Observation of seasonal variations of the flux of high-energy atmospheric neutrinos with IceCube
- 2023
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In: European Physical Journal C. - : Springer. - 1434-6044 .- 1434-6052. ; 83:9
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Journal article (peer-reviewed)abstract
- Atmospheric muon neutrinos are produced by meson decays in cosmic-ray-induced air showers. The flux depends on meteorological quantities such as the air temperature, which affects the density of air. Competition between decay and re-interaction of those mesons in the first particle production generations gives rise to a higher neutrino flux when the air density in the stratosphere is lower, corresponding to a higher temperature. A measurement of a temperature dependence of the atmospheric νμ flux provides a novel method for constraining hadronic interaction models of air showers. It is particularly sensitive to the production of kaons. Studying this temperature dependence for the first time requires a large sample of high-energy neutrinos as well as a detailed understanding of atmospheric properties. We report the significant (>10σ) observation of a correlation between the rate of more than 260,000 neutrinos, detected by IceCube between 2012 and 2018, and atmospheric temperatures of the stratosphere, measured by the Atmospheric Infrared Sounder (AIRS) instrument aboard NASA’s AQUA satellite. For the observed 10 % seasonal change of effective atmospheric temperature we measure a 3.5(3) % change in the muon neutrino flux. This observed correlation deviates by about 2-3 standard deviations from the expected correlation of 4.3 % as obtained from theoretical predictions under the assumption of various hadronic interaction models.
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| 2. |
- Abbasi, R., et al.
(author)
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Limits on Neutrino Emission from GRB 221009A from MeV to PeV Using the IceCube Neutrino Observatory
- 2023
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In: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 946:1
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Journal article (peer-reviewed)abstract
- Gamma-ray bursts (GRBs) have long been considered a possible source of high-energy neutrinos. While no correlations have yet been detected between high-energy neutrinos and GRBs, the recent observation of GRB 221009A-the brightest GRB observed by Fermi-GBM to date and the first one to be observed above an energy of 10 TeV-provides a unique opportunity to test for hadronic emission. In this paper, we leverage the wide energy range of the IceCube Neutrino Observatory to search for neutrinos from GRB 221009A. We find no significant deviation from background expectation across event samples ranging from MeV to PeV energies, placing stringent upper limits on the neutrino emission from this source.
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| 14. |
- de Graauw, Th., et al.
(author)
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The Herschel-Heterodyne Instrument for the Far-Infrared (HIFI)
- 2010
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In: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 518, s. L6-
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Journal article (peer-reviewed)abstract
- Aims: This paper describes the Heterodyne Instrument for the Far-Infrared (HIFI) that was launched onboard ESA's Herschel Space Observatory in May 2009. Methods: The instrument is a set of 7 heterodyne receivers that are electronically tuneable, covering 480-1250 GHz with SIS mixers and the 1410-1910 GHz range with hot electron bolometer (HEB) mixers. The local oscillator (LO) subsystem comprises a Ka-band synthesizer followed by 14 chains of frequency multipliers and 2 chains for each frequency band. A pair of auto-correlators and a pair of acousto-optical spectrometers process the two IF signals from the dual-polarization, single-pixel front-ends to provide instantaneous frequency coverage of 2 × 4 GHz, with a set of resolutions (125 kHz to 1 MHz) that are better than 0.1 km s-1. Results: After a successful qualification and a pre-launch TB/TV test program, the flight instrument is now in-orbit and completed successfully the commissioning and performance verification phase. The in-orbit performance of the receivers matches the pre-launch sensitivities. We also report on the in-orbit performance of the receivers and some first results of HIFI's operations. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.
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| 15. |
- Leebens-Mack, James H., et al.
(author)
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One thousand plant transcriptomes and the phylogenomics of green plants
- 2019
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In: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 574:7780, s. 679-
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Journal article (peer-reviewed)abstract
- Green plants (Viridiplantae) include around 450,000-500,000 species(1,2) of great diversity and have important roles in terrestrial and aquatic ecosystems. Here, as part of the One Thousand Plant Transcriptomes Initiative, we sequenced the vegetative transcriptomes of 1,124 species that span the diversity of plants in a broad sense (Archaeplastida), including green plants (Viridiplantae), glaucophytes (Glaucophyta) and red algae (Rhodophyta). Our analysis provides a robust phylogenomic framework for examining the evolution of green plants. Most inferred species relationships are well supported across multiple species tree and supermatrix analyses, but discordance among plastid and nuclear gene trees at a few important nodes highlights the complexity of plant genome evolution, including polyploidy, periods of rapid speciation, and extinction. Incomplete sorting of ancestral variation, polyploidization and massive expansions of gene families punctuate the evolutionary history of green plants. Notably, we find that large expansions of gene families preceded the origins of green plants, land plants and vascular plants, whereas whole-genome duplications are inferred to have occurred repeatedly throughout the evolution of flowering plants and ferns. The increasing availability of high-quality plant genome sequences and advances in functional genomics are enabling research on genome evolution across the green tree of life.
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| 16. |
- Bossard, G., et al.
(author)
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Integral invariants in maximally supersymmetric Yang-Mills theories
- 2011
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In: Journal of High Energy Physics (JHEP). - 1126-6708 .- 1029-8479. ; :5, s. 021-
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Journal article (peer-reviewed)abstract
- Integral invariants in maximally supersymmetric Yang-Mills theories are discussed in spacetime dimensions 4 <= D <= 10 for SU(k) gauge groups. It is shown that, in addition to the action, there are three special invariants in all dimensions. Two of these, the single-and double-trace F-4 invariants, are of Chern-Simons type in D = 9, 10 and BPS type in D <= 8, while the third, the double-trace of two derivatives acting on F-4, can be expressed in terms of a gauge-invariant super-D-form in all dimensions. We show that the super-ten-forms for D = 10 F-4 invariants have interesting cohomological properties and we also discuss some features of other invariants, including the single-trace d(2)F(4), which has a special form in D = 10. The implications of these results for ultra-violet divergences are discussed in the framework of algebraic renormalisation.
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| 17. |
- Gromada, J, et al.
(author)
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Glucagon-like peptide I increases cytoplasmic calcium in insulin-secreting beta TC3-cells by enhancement of intracellular calcium mobilization
- 1995
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In: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797. ; 44:7, s. 767-774
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Journal article (peer-reviewed)abstract
- In the insulin-secreting beta-cell line beta TC3, stimulation with 11.2 mmol/l glucose caused a rise in the intracellular free Ca2+ concentration ([Ca2+]i) in only 18% of the tested cells. The number of glucose-responsive cells increased after pretreatment of the cells with glucagon-like peptide I (GLP-I)(7-36)amide and at 10(-11) mol/l; 84% of the cells responded to glucose with a rise in [Ca2+]i. GLP-I(7-36)amide induces a rapid increase in [Ca2+]i only in cells exposed to elevated glucose concentrations (> or = 5.6 mmol/l). The action of GLP-I(7-36)amide and forskolin involved a 10-fold increase in cytoplasmic cAMP concentration and was mediated by activation of protein kinase A. It was not associated with an effect on the membrane potential but required some (small) initial entry of Ca2+ through voltage-dependent L-type Ca2+ channels, which then produced a further increase in [Ca2+]i by mobilization from intracellular stores. The latter effect reflected Ca(2+)-induced Ca2+ release and was blocked by ryanodine. Similar increases in [Ca2+]i were also observed in voltage-clamped cells, although there was neither activation of a background (Ca(2+)-permeable) inward current nor enhancement of the voltage-dependent L-type Ca2+ current. These observations are consistent with GLP-I(7-36) amide inducing glucose sensitivity by promoting mobilization of Ca2+ from intracellular stores. We propose that this novel action of GLP-I(7-36)amide represents an important factor contributing to its insulinotropic action.
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| 18. |
- Henriksen, Kim, et al.
(author)
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Dissociation of Bone Resorption and Bone Formation in Adult Mice with a Non-Functional V-ATPase in Osteoclasts Leads to Increased Bone Strength
- 2011
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In: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:11
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Journal article (peer-reviewed)abstract
- Osteopetrosis caused by defective acid secretion by the osteoclast, is characterized by defective bone resorption, increased osteoclast numbers, while bone formation is normal or increased. In contrast the bones are of poor quality, despite this uncoupling of formation from resorption. To shed light on the effect of uncoupling in adult mice with respect to bone strength, we transplanted irradiated three-month old normal mice with hematopoietic stem cells from control or oc/oc mice, which have defective acid secretion, and followed them for 12 to 28 weeks. Engraftment levels were assessed by flow cytometry of peripheral blood. Serum samples were collected every six weeks for measurement of bone turnover markers. At termination bones were collected for mu CT and mechanical testing. An engraftment level of 98% was obtained. From week 6 until termination bone resorption was significantly reduced, while the osteoclast number was increased when comparing oc/oc to controls. Bone formation was elevated at week 6, normalized at week 12, and reduced onwards. mu CT and mechanical analyses of femurs and vertebrae showed increased bone volume and bone strength of cortical and trabecular bone. In conclusion, these data show that attenuation of acid secretion in adult mice leads to uncoupling and improves bone strength.
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| 19. |
- Korchynska, S, et al.
(author)
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A hypothalamic dopamine locus for psychostimulant-induced hyperlocomotion in mice
- 2022
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In: Nature communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 13:1, s. 5944-
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Journal article (peer-reviewed)abstract
- The lateral septum (LS) has been implicated in the regulation of locomotion. Nevertheless, the neurons synchronizing LS activity with the brain’s clock in the suprachiasmatic nucleus (SCN) remain unknown. By interrogating the molecular, anatomical and physiological heterogeneity of dopamine neurons of the periventricular nucleus (PeVN; A14 catecholaminergic group), we find that Th+/Dat1+ cells from its anterior subdivision innervate the LS in mice. These dopamine neurons receive dense neuropeptidergic innervation from the SCN. Reciprocal viral tracing in combination with optogenetic stimulation ex vivo identified somatostatin-containing neurons in the LS as preferred synaptic targets of extrahypothalamic A14 efferents. In vivo chemogenetic manipulation of anterior A14 neurons impacted locomotion. Moreover, chemogenetic inhibition of dopamine output from the anterior PeVN normalized amphetamine-induced hyperlocomotion, particularly during sedentary periods. Cumulatively, our findings identify a hypothalamic locus for the diurnal control of locomotion and pinpoint a midbrain-independent cellular target of psychostimulants.
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| 20. |
- Leu, E., et al.
(author)
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Fatty acid dynamics during the spring bloom in a High Arctic fjord: importance of abiotic factors versus community changes
- 2006
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In: Canadian Journal of Fisheries and Aquatic Sciences. - 0706-652X. ; 63:12, s. 2760-2779
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Journal article (peer-reviewed)abstract
- We followed the fatty acid composition of particulate organic matter (POM) in a High Arctic fjord (79 degrees N; Svalbard, Norway) during and after the spring bloom. The content of essential polyunsaturated fatty acids (PUFAs) was highest (45% of total fatty acids) at the beginning of the bloom, well before the biomass maximum, and decreased linearly towards the end (30%). During the postbloom period, the concentrations of PUFAs remained stable, between 25% and 30%. Redundancy analysis was used to identify the environmental factors that explained the observed variability in the fatty acid composition of phytoplankton. A particular emphasis was put on the potential influence of high irradiances. During the spring bloom, nutrient availability (Si and N), as well as shifts in phytoplankton community composition and chlorophyll a, were shown to account for much of the pattern in fatty acid composition. During the postbloom period, particularly during periods of stratification, light had a pronounced effect on the fatty acid composition. In general, we found a decrease in the relative amount of PUFAs under high light intensities and nutrient limitation.
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| 21. |
- Wells, M. L., et al.
(author)
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Harmful algal blooms and climate change: Learning from the past and present to forecast the future
- 2015
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In: Harmful Algae. - : Elsevier BV. - 1568-9883. ; 49, s. 68-93
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Journal article (peer-reviewed)abstract
- Climate change pressures will influence marine planktonic systems globally, and it is conceivable that harmful algal blooms may increase in frequency and severity. These pressures will be manifest as alterations in temperature, stratification, light, ocean acidification, precipitation-induced nutrient inputs, and grazing, but absence of fundamental knowledge of the mechanisms driving harmful algal blooms frustrates most hope of forecasting their future prevalence. Summarized here is the consensus of a recent workshop held to address what currently is known and not known about the environmental conditions that favor initiation and maintenance of harmful algal blooms. There is expectation that harmful algal bloom (HAB) geographical domains should expand in some cases, as will seasonal windows of opportunity for harmful algal blooms at higher latitudes. Nonetheless there is only basic information to speculate upon which regions or habitats HAB species may be the most resilient or susceptible. Moreover, current research strategies are not well suited to inform these fundamental linkages. There is a critical absence of tenable hypotheses for how climate pressures mechanistically affect HAB species, and the lack of uniform experimental protocols limits the quantitative cross-investigation comparisons essential to advancement. A HAB "best practices" manual would help foster more uniform research strategies and protocols, and selection of a small target list of model HAB species or isolates for study would greatly promote the accumulation of knowledge. Despite the need to focus on keystone species, more studies need to address strain variability within species, their responses under multifactorial conditions, and the retrospective analyses of long-term plankton and cyst core data; research topics that are departures from the norm. Examples of some fundamental unknowns include how larger and more frequent extreme weather events may break down natural biogeographic barriers, how stratification may enhance or diminish HAB events, how trace nutrients (metals, vitamins) influence cell toxicity, and how grazing pressures may leverage, or mitigate HAB development. There is an absence of high quality time-series data in most regions currently experiencing HAB outbreaks, and little if any data from regions expected to develop HAB events in the future. A subset of observer sites is recommended to help develop stronger linkages among global, national, and regional climate change and HAB observation programs, providing fundamental datasets for investigating global changes in the prevalence of harmful algal blooms. Forecasting changes in HAB patterns over the next few decades will depend critically upon considering harmful algal blooms within the competitive context of plankton communities, and linking these insights to ecosystem, oceanographic and climate models. From a broader perspective, the nexus of HAB science and the social sciences of harmful algal blooms is inadequate and prevents quantitative assessment of impacts of future HAB changes on human well-being. These and other fundamental changes in HAB research will be necessary if HAB science is to obtain compelling evidence that climate change has caused alterations in HAB distributions, prevalence or character, and to develop the theoretical, experimental, and empirical evidence explaining the mechanisms underpinning these ecological shifts. © 2015 Elsevier B.V.
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| 22. |
- Al-Handal, Adil Y, 1952, et al.
(author)
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Navithidium gen. nov., a new monoraphid diatom (Bacillariophyceae) genus based on Achnanthes delicatissima Simonsen
- 2021
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In: Diatom Research. - 0269-249X. ; 36:2, s. 133-141
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Journal article (peer-reviewed)abstract
- We investigated the ultrastructure of Achnanthes delicatissima Simonsen in materials collected from the Swedish Baltic coast. Valve structure differs markedly from that of Achnanthes sensu lato, particularly in the absence of cribrate areolae which separates Achnanthes from all other members of the family Achnanthaceae. Comparing this species with those recently described achnanthoid genera, such as Scalariella Riaux-Gobin & Witkowski and Madinithidium Witkowski, Desrosiers & Riaux-Gobin revealed morphological differences that warrant the erection of a new genus, Navithidium. Owing to the small size of the frustules, it is difficult to identify Navithidium delicatissima in light microscopy due to similarities with some closely related taxa like Achnanthidium pseudochamaepinnularia (which is here transferred to Navithidium). A comparison with related genera is provided and discussed. © 2021 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
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| 23. |
- ALDEN, M, et al.
(author)
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INFLUENCE OF SELECTED VARIABLES ON HEAT OF FUSION DETERMINATIONS BY OSCILLATING DSC
- 1995
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In: THERMOCHIMICA ACTA. - : ELSEVIER SCIENCE BV. - 0040-6031. ; 265, s. 89-102
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Journal article (other academic/artistic)abstract
- The influence of variables on the determination of the heat of fusion for phases with different crystallinity was investigated using oscillating differential scanning calorimetry (ODSC). The hydrophobic drug griseofulvin (GRIS) represented a crystalline s
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| 25. |
- Bjarnadottir, M, et al.
(author)
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Intracellular accumulation of the amyloidogenic L68Q variant of human cystatin C in NIH/3T3 cells
- 1998
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In: Molecular Pathology. - : BMJ. - 1366-8714. ; 51, s. 317-326
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Journal article (peer-reviewed)abstract
- AIM: To study the cellular transport of L68Q cystatin C, the cystatin variant causing amyloidosis and brain haemorrhage in patients suffering from hereditary cystatin C amyloid angiopathy (HCCAA).METHODS: Expression vectors for wild-type and L68Q cystatin C were constructed and used to transfect mouse NIH/3T3 cells. Stable cell clones were isolated after cotransfection with pSV2neo. Clones expressing human wild-type and L68Q cystatin C were compared with respect to secreted cystatin C by enzyme linked immunosorbent assay (ELISA), and for intracellular cystatin C by western blotting and immunofluorescence cytochemistry. Colocalisation studies in cells were performed by double staining with antibodies against human cystatin C and marker proteins for lysosomes, the Golgi apparatus, or the endoplasmic reticulum, and evaluated by confocal microscopy.RESULTS: Concentrations of human cystatin C secreted from transfected NIH/3T3 cells were similar to those secreted from human cells in culture. In general, clones expressing the gene encoding L68Q cystatin C secreted slightly lower amounts of the protein than clones expressing wild-type human cystatin C. Both immunofluorescence cytochemistry and western blotting experiments showed an increased accumulation of cystatin C in cells expressing the gene encoding L68Q cystatin C compared with cells expressing the gene for the wild-type protein. The intracellularly accumulating L68Q cystatin C was insoluble and located mainly in the endoplasmic reticulum.CONCLUSIONS: The cellular transport of human cystatin C is impeded by the pathogenic amino acid substitution Leu68-->Gln. The resulting intracellular accumulation and increased localised concentration of L68Q cystatin C might be an important event in the molecular pathophysiology of amyloid formation and brain haemorrhage in patients with HCCAA.
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