| 1. |
- Acharya, B. S., et al.
(författare)
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Introducing the CTA concept
- 2013
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Ingår i: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 43, s. 3-18
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The Cherenkov Telescope Array (CTA) is a new observatory for very high-energy (VHE) gamma rays. CTA has ambitions science goals, for which it is necessary to achieve full-sky coverage, to improve the sensitivity by about an order of magnitude, to span about four decades of energy, from a few tens of GeV to above 100 TeV with enhanced angular and energy resolutions over existing VHE gamma-ray observatories. An international collaboration has formed with more than 1000 members from 27 countries in Europe, Asia, Africa and North and South America. In 2010 the CTA Consortium completed a Design Study and started a three-year Preparatory Phase which leads to production readiness of CTA in 2014. In this paper we introduce the science goals and the concept of CTA, and provide an overview of the project. (C) 2013 Elsevier B.V. All rights reserved.
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| 2. |
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| 3. |
- Actis, M., et al.
(författare)
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Design concepts for the Cherenkov Telescope Array CTA : an advanced facility for ground-based high-energy gamma-ray astronomy
- 2011
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Ingår i: Experimental astronomy. - : Springer. - 0922-6435 .- 1572-9508. ; 32:3, s. 193-316
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Tidskriftsartikel (refereegranskat)abstract
- Ground-based gamma-ray astronomy has had a major breakthrough with the impressive results obtained using systems of imaging atmospheric Cherenkov telescopes. Ground-based gamma-ray astronomy has a huge potential in astrophysics, particle physics and cosmology. CTA is an international initiative to build the next generation instrument, with a factor of 5-10 improvement in sensitivity in the 100 GeV-10 TeV range and the extension to energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays (one in the north, one in the south) for full sky coverage and will be operated as open observatory. The design of CTA is based on currently available technology. This document reports on the status and presents the major design concepts of CTA.
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| 4. |
- Acharyya, A., et al.
(författare)
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Monte Carlo studies for the optimisation of the Cherenkov Telescope Array layout
- 2019
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Ingår i: Astroparticle physics. - : Elsevier. - 0927-6505 .- 1873-2852. ; 111, s. 35-53
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Tidskriftsartikel (refereegranskat)abstract
- The Cherenkov Telescope Array (CTA) is the major next-generation observatory for ground-based veryhigh-energy gamma-ray astronomy. It will improve the sensitivity of current ground-based instruments by a factor of five to twenty, depending on the energy, greatly improving both their angular and energy resolutions over four decades in energy (from 20 GeV to 300 TeV). This achievement will be possible by using tens of imaging Cherenkov telescopes of three successive sizes. They will be arranged into two arrays, one per hemisphere, located on the La Palma island (Spain) and in Paranal (Chile). We present here the optimised and final telescope arrays for both CTA sites, as well as their foreseen performance, resulting from the analysis of three different large-scale Monte Carlo productions.
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| 5. |
- Ackermann, M., et al.
(författare)
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Fermi-LAT Observations of the Gamma-Ray Burst GRB 130427A
- 2014
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 343:6166, s. 42-47
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Tidskriftsartikel (refereegranskat)abstract
- The observations of the exceptionally bright gamma-ray burst (GRB) 130427A by the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope provide constraints on the nature of these unique astrophysical sources. GRB 130427A had the largest fluence, highest-energy photon (95 GeV), longest gamma-ray duration (20 hours), and one of the largest isotropic energy releases ever observed from a GRB. Temporal and spectral analyses of GRB 130427A challenge the widely accepted model that the nonthermal high-energy emission in the afterglow phase of GRBs is synchrotron emission radiated by electrons accelerated at an external shock.
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| 6. |
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| 7. |
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| 8. |
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| 9. |
- Coughlin, Michael W., et al.
(författare)
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GROWTH on S190425z : Searching Thousands of Square Degrees to Identify an Optical or Infrared Counterpart to a Binary Neutron Star Merger with the Zwicky Transient Facility and Palomar Gattini-IR
- 2019
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8205 .- 2041-8213. ; 885:1
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Tidskriftsartikel (refereegranskat)abstract
- The third observing run by LVC has brought the discovery of many compact binary coalescences. Following the detection of the first binary neutron star merger in this run (LIGO/Virgo S190425z), we performed a dedicated follow-up campaign with the Zwicky Transient Facility (ZTF) and Palomar Gattini-IR telescopes. The initial skymap of this single-detector gravitational wave (GW) trigger spanned most of the sky observable from Palomar Observatory. Covering 8000 deg(2) of the initial skymap over the next two nights, corresponding to 46% integrated probability, ZTF system achieved a depth of 21 m(AB) in g- and r-bands. Palomar Gattini-IR covered 2200 square degrees in J-band to a depth of 15.5 mag, including 32% integrated probability based on the initial skymap. The revised skymap issued the following day reduced these numbers to 21% for the ZTF and 19% for Palomar Gattini-IR. We narrowed 338,646 ZTF transient ?alerts? over the first two nights of observations to 15 candidate counterparts. Two candidates, ZTF19aarykkb and ZTF19aarzaod, were particularly compelling given that their location, distance, and age were consistent with the GW event, and their early optical light curves were photometrically consistent with that of kilonovae. These two candidates were spectroscopically classified as young core-collapse supernovae. The remaining candidates were ruled out as supernovae. Palomar Gattini-IR did not identify any viable candidates with multiple detections only after merger time. We demonstrate that even with single-detector GW events localized to thousands of square degrees, systematic kilonova discovery is feasible.
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| 10. |
- Dufies, M, et al.
(författare)
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Plk1, upregulated by HIF-2, mediates metastasis and drug resistance of clear cell renal cell carcinoma
- 2021
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Ingår i: Communications biology. - : Springer Science and Business Media LLC. - 2399-3642. ; 4:1, s. 166-
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Tidskriftsartikel (refereegranskat)abstract
- Polo-like kinase 1 (Plk1) expression is inversely correlated with survival advantages in many cancers. However, molecular mechanisms that underlie Plk1 expression are poorly understood. Here, we uncover a hypoxia-regulated mechanism of Plk1-mediated cancer metastasis and drug resistance. We demonstrated that a HIF-2-dependent regulatory pathway drives Plk1 expression in clear cell renal cell carcinoma (ccRCC). Mechanistically, HIF-2 transcriptionally targets the hypoxia response element of the Plk1 promoter. In ccRCC patients, high expression of Plk1 was correlated to poor disease-free survival and overall survival. Loss-of-function of Plk1 in vivo markedly attenuated ccRCC growth and metastasis. High Plk1 expression conferred a resistant phenotype of ccRCC to targeted therapeutics such as sunitinib, in vitro, in vivo, and in metastatic ccRCC patients. Importantly, high Plk1 expression was defined in a subpopulation of ccRCC patients that are refractory to current therapies. Hence, we propose a therapeutic paradigm for improving outcomes of ccRCC patients.
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| 11. |
- Desroches, C, et al.
(författare)
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Synthesis, characterization and optical power limiting behaviour of phenylazo- and 4-nitrophenylazo-tetrahydroxytetrathiacalix[4]arene
- 2001
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Ingår i: Journal of Materials Chemistry. - 0959-9428 .- 1364-5501. ; 11:12, s. 3014-3017
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Tidskriftsartikel (refereegranskat)abstract
- p-Tetrakis(4-nitrophenylazo) tetrahydroxytetrathiacalix[4] arene and p-tetrakis(phenylazo) tetrahydroxytetrathiacalix[4] arene were prepared and fully characterized using H-1 and C-13 NMR, mass spectroscopy, thermogravimetric analysis and differential scanning calorimetry. The solid-state structure of p-tetrakis(4-nitrophenylazo) tetrahydroxytetrathiacalix[4] arene was investigated by single crystal X-ray diffraction. It crystallized in the triclinic system (space group: P (1) over bar). z-Scan experiments were performed on the p-tetrakis(4-nitrophenylazo) tetrahydroxytetrathiacalix[ 4] arene showing non linear absorption due to two photon absorption with a TPA cross-section of about 50 x 10(-50) cm(4) s per photon. Optical power limiting measurements on the p-tetrakis( phenylazo) tetrahydroxytetrathiacalix[ 4] arene at 532 nm (48% linear transmission) was found to limit the energy to similar to9 muJ.
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| 12. |
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| 13. |
- Kariniemi, M., et al.
(författare)
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Effect of Blanket Properties on Web Tension in Offset Printing
- 2010
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Ingår i: Advances in Printing and Media Technology. - Montreal, Canada.
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Konferensbidrag (refereegranskat)abstract
- VTT and KCL together with several companies in the printing value chain have studied how to control web tension in different parts of a printing press. Extensive trials on printing presses, at pilot scale and at laboratory scale have yielded data for modeling work. Modeling was carried out with statistical methods and by finite element method (FEM). Results show the extent to which paper and printing blankets affect tension formation in a printing press. The main emphasis of this paper is on the effect different printing blanket types have on web tension.It was found that printing blankets have a clear effect on web tension. The degree of tension change is affected by the type of blanket, nip pressure, distances between the blankets, moisture, paper properties and the combination of blanket types in different printing units. Depending on their feeding properties and their effect on web tension, in general, the blankets can be distinguished as negative, neutral and positive. Also the blanket’s effect on web tension is influenced strongly by the type of adjacent blankets. The interactions of fountain solution, ink, nip, blanket and paper had also an effect on the tension formation. The paper experiences a very high rate of strain inside the printing nips, which can affect the paper’s response and therefore tension after the nips. Results suggest that tension cannot be solely predicted with the elastic paper properties measured by conventional methods.
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| 14. |
- Parola, S., et al.
(författare)
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Optoelectronic properties of p-i-n heterojunctions based on germanium nanocrystals
- 2013
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 114:3, s. 033510-
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the possibility of using physical vapour deposited Ge nanocrystals (NCs) in optoelectronic devices such as solar cells. We have prepared p-i-n heterojunctions based on p(+)-doped Si substrate/undoped Ge NCs/ZnO: Al layer stacks and their optoelectronic properties were characterised. Under light, the generation of photo-carriers from the Ge NCs themselves was demonstrated. The photovoltaic behaviour of the p-i-n structure was also highlighted, with a measured Voc of 224 mV compared to 580 mV in theory. The discrepancy between theory and experiment was discussed on the basis of TEM observations, optical and carrier generation measurements as well as modelling.
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| 15. |
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| 16. |
- Sorvari, J., et al.
(författare)
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Effect of some printing nip variables on web tension
- 2016
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Ingår i: Nordic Pulp & Paper Research Journal. - : SPCI. - 0283-2631 .- 2000-0669. ; 31:3, s. 491-498
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Tidskriftsartikel (refereegranskat)abstract
- Good runnability of paper web is an important factor for improving performance of printing process. Printing nips cause web tension variations which are known to affect web runnability. However, rather little is known about the exact effect of the nips on web tension. In this work, two dimensional finite element simulations are used to study the effect of some printing nip variables on web tension. In addition, the simulations results are compared with press trial results. The results show that nip blanket type and indentation depth has great impact on web tension. Particularly, mixing of different blanket types in adjacent printing units can cause severe variations to web tension. It is concluded that to attain good runnability the feeding characteristics of the printing blankets as well as the press settings should be known.
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| 17. |
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