| 1. |
- Gustafsson, Erik, et al.
(författare)
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Carbon cycling on the East Siberian Arctic Shelf – a change in air-sea CO2 flux induced by mineralization of terrestrial organic carbon
- 2017
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189.
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Tidskriftsartikel (refereegranskat)abstract
- Measurements from the SWERUS-C3 and ISSS-08 Arctic expeditions were used to calibrate and validate a new physical-biogeochemical model developed to quantify key carbon cycling processes on the East Siberian Arctic Shelf (ESAS). The model was used in a series of experimental simulations with the specific aim to investigate the pathways of terrestrial dissolved and particulate organic carbon (DOCter and POCter) supplied to the shelf. Rivers supply on average 8.5 Tg C yr−1 dissolved inorganic carbon (DIC), and further 8.5 and 1.1 Tg C yr−1 DOCter and POCter respectively. Based on observed and simulated DOC concentrations and stable isotope values (δ13CDOC) in shelf waters, we estimate that only some 20 % of the riverine DOCter is labile. According to our model results, an additional supply of approximately 14 Tg C yr−1 eroded labile POCter is however required to describe the observed stable isotope values of DIC (δ13CDIC). Degradation of riverine DOCter and POCter results in a 1.8 Tg C yr−1 reduction in the uptake of atmospheric CO2, while degradation of eroded POCter results in an additional 10 Tg C yr−1 reduction. Our calculations indicate nevertheless that the ESAS is an overall small net sink for atmospheric CO2 (1.7 Tg C yr−1). The external carbon sources are largely compensated by a net export from the shelf to the Arctic Ocean (31 Tg C yr−1), and to a smaller degree by a permanent burial in the sediments (2.7 Tg C yr−1).
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| 2. |
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| 3. |
- Gustafsson, Robert, et al.
(författare)
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Crystal Structure of the Emerging Cancer Target MTHFD2 in Complex with a Substrate-Based Inhibitor
- 2017
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Ingår i: Cancer Research. - : AMER ASSOC CANCER RESEARCH. - 0008-5472 .- 1538-7445. ; 77:4, s. 937-948
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Tidskriftsartikel (refereegranskat)abstract
- To sustain their proliferation, cancer cells become dependent on one-carbon metabolism to support purine and thymidylate synthesis. Indeed, one of the most highly upregulated enzymes during neoplastic transformation is MTHFD2, a mitochondrial methylenetetrahydrofolate dehydrogenase and cyclohydrolase involved in one-carbon metabolism. Because MTHFD2 is expressed normally only during embryonic development, it offers a disease-selective therapeutic target for eradicating cancer cells while sparing healthy cells. Here we report the synthesis and preclinical characterization of the first inhibitor of human MTHFD2. We also disclose the first crystal structure of MTHFD2 in complex with a substrate-based inhibitor and the enzyme cofactors NAD(+) and inorganic phosphate. Our work provides a rationale for continued development of a structural framework for the generation of potent and selective MTHFD2 inhibitors for cancer treatment.
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| 4. |
- Humborg, Christoph, et al.
(författare)
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Sea-air exchange patterns along the central and outer East Siberian Arctic Shelf as inferred from continuous CO2, stable isotope, and bulk chemistry measurements
- 2017
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Ingår i: Global Biogeochemical Cycles. - 0886-6236 .- 1944-9224. ; 31:7, s. 1173-1191
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Tidskriftsartikel (refereegranskat)abstract
- This large-scale quasi-synoptic study gives a comprehensive picture of sea-air CO 2 fluxes during the melt season in the central and outer Laptev Sea (LS) and East Siberian Sea (ESS). During a 7 week cruise we compiled a continuous record of both surface water and air CO 2 concentrations, in total 76,892 measurements. Overall, the central and outer parts of the ESAS constituted a sink for CO 2 , and we estimate a median uptake of 9.4 g C m -2 yr -1 or 6.6 Tg C yr -1 . Our results suggest that while the ESS and shelf break waters adjacent to the LS and ESS are net autotrophic systems, the LS is a net heterotrophic system. CO 2 sea-air fluxes for the LS were 4.7 g C m -2 yr -1 , and for the ESS we estimate an uptake of 7.2 g C m -2 yr -1 . Isotopic composition of dissolved inorganic carbon (δ 13 C DIC and δ 13 C CO2 ) in the water column indicates that the LS is depleted in δ 13 C DIC compared to the Arctic Ocean (ArcO) and ESS with an offset of 0.5‰ which can be explained by mixing of δ 13 C DIC -depleted riverine waters and 4.0 Tg yr -1 respiration of OC ter ; only a minor part (0.72 Tg yr -1 ) of this respired OC ter is exchanged with the atmosphere. Property-mixing diagrams of total organic carbon and isotope ratio (δ 13 C SPE-DOC ) versus dissolved organic carbon (DOC) concentration diagram indicate conservative and nonconservative mixing in the LS and ESS, respectively. We suggest land-derived particulate organic carbon from coastal erosion as an additional significant source for the depleted δ 13 C DIC .
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| 5. |
- Aartsen, M. G., et al.
(författare)
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The IceCube Neutrino Observatory : instrumentation and online systems
- 2017
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Ingår i: Journal of Instrumentation. - : IOP PUBLISHING LTD. - 1748-0221. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- The IceCube Neutrino Observatory is a cubic-kilometer-scale high-energy neutrino detector built into the ice at the South Pole. Construction of IceCube, the largest neutrino detector built to date, was completed in 2011 and enabled the discovery of high-energy astrophysical neutrinos. We describe here the design, production, and calibration of the IceCube digital optical module (DOM), the cable systems, computing hardware, and our methodology for drilling and deployment. We also describe the online triggering and data filtering systems that select candidate neutrino and cosmic ray events for analysis. Due to a rigorous pre-deployment protocol, 98.4% of the DOMs in the deep ice are operating and collecting data. IceCube routinely achieves a detector uptime of 99% by emphasizing software stability and monitoring. Detector operations have been stable since construction was completed, and the detector is expected to operate at least until the end of the next decade.
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| 6. |
- Aziz, Imran, et al.
(författare)
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Effects of proton irradiation on 60 GHz CMOS transceiver chip for multi-Gbps communication in high-energy physics experiments
- 2019
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Ingår i: The Journal of Engineering. - : INST ENGINEERING TECHNOLOGY-IET. - 2051-3305. ; :8, s. 5391-5396
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Tidskriftsartikel (refereegranskat)abstract
- This article presents the experimental results of 17 MeV proton irradiation on a 60 GHz low power, half-duplex transceiver (TRX) chip implemented in 65 nm CMOS technology. It supports short range point-to-point data rate up to 6 Gbps by employing on-off keying (OOK). To investigate the irradiation hardness for high-energy physics (HEP) applications, two TRX chips were irradiated with total ionising doses (TID) of 74 and 42 kGy and fluence of 1.4 x 10(14)N(eq)/cm(2) and 0.8 x 10(14)N(eq)/cm(2) for RX and TX modes, respectively. The chips were characterised by pre- and post-irradiation analogue voltage measurements on different circuit blocks as well as through the analysis of wireless transmission parameters like bit error rate (BER), eye diagram, jitter etc. Post-irradiation measurements have shown certain reduction in performance but both TRX chips have been found operational through over the air measurements at 5 Gbps. Moreover, very small shift in the carrier frequency was observed after the irradiation.
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| 7. |
- Barwick, S. W., et al.
(författare)
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A first search for cosmogenic neutrinos with the ARIANNA Hexagonal Radio Array
- 2015
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Ingår i: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 70, s. 12-26
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Tidskriftsartikel (refereegranskat)abstract
- The ARIANNA experiment seeks to observe the diffuse flux of neutrinos in the 10(8)-10(10) GeV energy range using a grid of radio detectors at the surface of the Ross Ice Shelf of Antarctica. The detector measures the coherent Cherenkov radiation produced at radio frequencies, from about 100 MHz-1 GHz, by charged particle showers generated by neutrino interactions in the ice. The ARIANNA Hexagonal Radio Array (HRA) is being constructed as a prototype for the full array. During the 2013-14 austral summer, three HRA stations collected radio data which was wirelessly transmitted off site in nearly real-time. The performance of these stations is described and a simple analysis to search for neutrino signals is presented. The analysis employs a set of three cuts that reject background triggers while preserving 90% of simulated cosmogenic neutrino triggers. No neutrino candidates are found in the data and a model-independent 90% confidence level Neyman upper limit is placed on the all flavor nu + (nu) over bar flux in a sliding decade-wide energy bin. The limit reaches a minimum of 1.9 x 10(-23) GeV-1 cm(-2) s(-1) sr(-1) in the 10(8.5)-10(9.5) GeV energy bin. Simulations of the performance of the full detector are also described. The sensitivity of the full ARIANNA experiment is presented and compared with current neutrino flux models.
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| 8. |
- Carlsson, Rose-Marie, et al.
(författare)
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Two consecutive randomized controlled pertussis booster trials in children initially vaccinated in infancy with an acellular vaccine: The first with a five-component Tdap vaccine to 5-year olds and the second with five- or monocomponent Tdap vaccines at age 14-15 years
- 2015
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Ingår i: Vaccine. - : Elsevier BV. - 0264-410X .- 1873-2518. ; 33:31, s. 3717-3725
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Tidskriftsartikel (refereegranskat)abstract
- Prior study children from a DTaP efficacy trial were recruited at ages 5 and 15 years to randomized booster trials addressing immunogenicity and reactogenicity; 475 preschool children received mixed or separate injections of a reduced antigen vaccine (Tdap5, Sanofi Pasteur MSD) and an inactivated polio vaccine, and 230 adolescents received the same or another booster vaccine (Tdap1, SSI, Denmark). Pre-vaccination antibody concentrations against pertussis antigens were significantly higher at 15 than 5 years of age, probably due to natural boosting between the studies. Tdap5 induced comparable anti-PT concentrations at both ages, but antibody responses were significantly higher to filamentous haemagglutinin, pertactin and fimbriae 2/3 in adolescents. As expected, a higher amount of PT (Tdap1, 20 mu g) induced a stronger anti-PT response than a lower amount (Tdap5, 2.5 mu g). The frequency of adverse events was low and there were no serious adverse reactions. All local reactions had an early onset and a short duration. A large swelling or redness of more than half of the upper arm circumference was reported in 8/475 5-year-olds and in 6/230 15-year-olds. Children vaccinated with Tdap5 reported more moderate pain in adolescence than at preschool age, whereas itching was only reported in preschool children. Sweden introduced DTaP vaccines in 1996 after a 17-year hiatus with no general pertussis vaccination and pertussis was still endemic at the time of the studies. The frequency of adverse events was nevertheless low in both preschool children and adolescents and antibody responses were adequate. These studies document immunogenicity and reactogenicity in a trial cohort consecutively vaccinated with acellular pertussis vaccines from infancy to adolescence. (C) 2015 Elsevier Ltd. All rights reserved.
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| 9. |
- Dittmeier, Sebastian, et al.
(författare)
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Wireless data transmission for high energy physics applications
- 2017
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Ingår i: EPJ Web of Conferences. - : EDP Sciences. - 2100-014X. ; 150
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Tidskriftsartikel (refereegranskat)abstract
- Silicon tracking detectors operated at high luminosity collider experiments pose a challenge for current and future readout systems regarding bandwidth, radiation, space and power constraints. With the latest developments in wireless communications, wireless readout systems might be an attractive alternative to commonly used wired optical and copper based readout architectures.The WADAPT group (Wireless Allowing Data and Power Transmission) has been formed to study the feasibility of wireless data transmission for future tracking detectors. These proceedings cover current developments focused on communication in the 60 GHz band. This frequency band offers a high bandwidth, a small form factor and an already mature technology. Motivation for wireless data transmission for high energy physics application and the developments towards a demonstrator prototype are summarized. Feasibility studies concerning the construction and operation of a wireless transceiver system have been performed. Data transmission tests with a transceiver prototype operating at even higher frequencies in the 240 GHz band are described. Data transmission at rates up to 10 Gb/s have been obtained successfully using binary phase shift keying.
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| 10. |
- Eriksson, Rickard
(författare)
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Structural Changes in Lithium Battery Materials Induced by Aging or Usage
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Li-ion batteries have a huge potential for use in electrification of the transportation sector. The major challenge to be met is the limited energy storage capacity of the battery pack: both the amount of energy which can be stored within the space available in the vehicle (defining its range), and the aging of the individual battery cells (determining how long a whole pack can deliver sufficient energy and power to drive the vehicle). This thesis aims to increase our knowledge and understanding of structural changes induced by aging and usage of the Li-ion battery materials involved.Aging processes have been studied in commercial-size Li-ion cells with two different chemistries. LiFePO4/graphite cells were aged under different conditions, and thereafter examined at different points along the electrodes by post mortem characterisation using SEM, XPS, XRD and electrochemical characterization in half-cells. The results revealed large differences in degradation behaviour under different aging conditions and in different regions of the same cell. The aging of LiMn2O4-LiCoO2/Li4Ti5O12 cells was studied under two different aging conditions. Post mortem analysis revealed a high degree of Mn/Co mixing within individual particles of the LiMn2O4-LiCoO2 composite electrode.Structural changes induced by lithium insertion were studied in two negative electrode materials: in Li0.5Ni0.25TiOPO4 using in situ XRD, and in Ni0.5TiOPO4 using EXAFS, XANES and HAXPES. It was shown that Li0.5Ni0.25TiOPO4 lost most of its long-range-order during lithiation, and that both Ni and Ti were involved in the charge compensation mechanism during lithiation/delithiation of Ni0.5TiOPO4, with small clusters of metal-like Ni forming during lithiation.Finally, in situ XRD studies were also made of the reaction pathways to form LiFeSO4F from two sets of reactants: either FeSO4·H2O and LiF, or Li2SO4 and FeF2. During the heat treatment, Li2SO4 and FeF2 react to form FeSO4·H2O and LiF in a first step. In a second step LiFeSO4F is formed. This underlines the importance of the structural similarities between LiFeSO4F and FeSO4·H2O in the formation process of LiFeSO4F.
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