| 1. |
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| 2. |
- 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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| 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. |
- 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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| 5. |
- 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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| 6. |
- 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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| 7. |
- 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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| 8. |
- Elfving, Kristina, et al.
(författare)
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Acute Uncomplicated Febrile Illness in Children Aged 2-59 months in Zanzibar : Aetiologies, Antibiotic Treatment and Outcome
- 2016
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Despite the fact that a large proportion of children with fever in Africa present at primary health care facilities, few studies have been designed to specifically study the causes of uncomplicated childhood febrile illness at this level of care, especially in areas like Zanzibar that has recently undergone a dramatic change from high to low malaria transmission.METHODS: We prospectively studied the aetiology of febrile illness in 677 children aged 2-59 months with acute uncomplicated fever managed by IMCI (Integrated Management of Childhood Illness) guidelines in Zanzibar, using point-of-care tests, urine culture, blood-PCR, chest X-ray (CXR) of IMCI-pneumonia classified patients, and multiple quantitative (q)PCR investigations of nasopharyngeal (NPH) (all patients) and rectal (GE) swabs (diarrhoea patients). For comparison, we also performed NPH and GE qPCR analyses in 167 healthy community controls. Final fever diagnoses were retrospectively established based on all clinical and laboratory data. Clinical outcome was assessed during a 14-day follow-up. The utility of IMCI for identifying infections presumed to require antibiotics was evaluated.FINDINGS: NPH-qPCR and GE-qPCR detected ≥1 pathogen in 657/672 (98%) and 153/164 (93%) of patients and 158/166 (95%) and 144/165 (87%) of controls, respectively. Overall, 57% (387/677) had IMCI-pneumonia, but only 12% (42/342) had CXR-confirmed pneumonia. Two patients were positive for Plasmodium falciparum. Respiratory syncytial virus (24.5%), influenza A/B (22.3%), rhinovirus (10.5%) and group-A streptococci (6.4%), CXR-confirmed pneumonia (6.2%), Shigella (4.3%) were the most common viral and bacterial fever diagnoses, respectively. Blood-PCR conducted in a sub-group of patients (n = 83) without defined fever diagnosis was negative for rickettsiae, chikungunya, dengue, Rift Valley fever and West Nile viruses. Antibiotics were prescribed to 500 (74%) patients, but only 152 (22%) had an infection retrospectively considered to require antibiotics. Clinical outcome was generally good. However, two children died. Only 68 (11%) patients remained febrile on day 3 and three of them had verified fever on day 14. An additional 29 (4.5%) children had fever relapse on day 14. Regression analysis determined C-reactive Protein (CRP) as the only independent variable significantly associated with CXR-confirmed pneumonia.CONCLUSIONS: This is the first study on uncomplicated febrile illness in African children that both applied a comprehensive laboratory panel and a healthy control group. A majority of patients had viral respiratory tract infection. Pathogens were frequently detected by qPCR also in asymptomatic children, demonstrating the importance of incorporating controls in fever aetiology studies. The precision of IMCI for identifying infections requiring antibiotics was low.
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| 9. |
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| 10. |
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| 11. |
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| 12. |
- Desroches, C., et al.
(författare)
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Design and synthesis of multifunctional thiacalixarenes and related metal derivatives for the preparation of sol-gel hybrid materials with non-linear optical properties
- 2003
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Ingår i: Dalton Transactions. - : Royal Society of Chemistry (RSC). - 1477-9226 .- 1477-9234. ; :10, s. 2085-2092
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Tidskriftsartikel (refereegranskat)abstract
- Thiacalixarenes bearing phenylazo or ethynylic groups on the lower rims were prepared and fully characterized. The functional groups were chosen for their ability to increase the electron delocalisation over the molecule and to form metal complexes. The formation of complexes between phenylazothiacalixarenes and metal salts (Zn2+, Ag+...), and the synthesis of platinum acetylides from ethynylthiacalixarenes were investigated. Preliminary studies on optical limiting properties for both ligands and complexes is reported. Clamping levels of ~4 µJ at 532 nm, were observed for both tetra(pentylphenylethynyl)tetrapropoxythiacalix[4]arcne (150 mM in THF, 99% transmission) and the platinum complex (30 mM in THF, 83% transmission). A second functionalisation (upper rims) with metal alkoxide groups has also been investigated in order to prepare hybrid materials incorporating the optically active molecule. The same macrocycle core was thus bifunctionalised, and used for its optical properties on one side and as a precursor of an inorganic network for hybrid materials on the other. © The Royal Society of Chemistry 2003.
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| 13. |
- 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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| 14. |
- Lunden, Hampus, et al.
(författare)
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Dispersion and self-orientation of gold nanoparticles in sol-gel hybrid silica - optical transmission properties
- 2015
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Ingår i: Journal of Materials Chemistry C. - : Royal Society of Chemistry. - 2050-7526 .- 2050-7534. ; 3:5, s. 1026-1034
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Tidskriftsartikel (refereegranskat)abstract
- Silica-based hybrid materials doped with gold nanoparticles (AuNPs) of different shapes were prepared with an adapted sol-gel technology (using MTEOS) and polished to high optical quality. Both spherical (23 and 45 nm in diameter) and bipyramidal (36, 50 and 78 nm in length) AuNPs were prepared and used as dopants. The AuNPs were functionalized with a novel silicone polymer for compatibilization with the sol-gel medium. The glass materials showed well defined localized surface plasmon resonance (SPR) absorbance from the visible to NIR. No redshifts in the spectra, due to the increase in doping concentration, were observed in the glasses, proving that no or very small SPR coupling effects occur. Spectroscopic Muller Matrix Ellipsometry showed that the shorter bipyramidal AuNPs (36 and 50 nm in length) have a clear preferred orientation in the MTEOS matrix, i.e. a tendency to be oriented with their long axis in the plane parallel to the glass surfaces. Dispersions of AuNPs have proven to be good optical power limiters that depend on particle size and geometry. The solid-state glass materials showed good optical power limiting at 532 nm for nanosecond pulses, which did not depend on the size or geometry of the AuNPs. In contrast to the observation at 532 nm, at 600 nm no optical limiting effect was observed. In these solids, as for dispersions of AuNPs, the optical limiting response is caused by scattering.
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| 15. |
- Lundén, H., et al.
(författare)
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Efficient reverse saturable absorption of sol-gel hybrid plasmonic glasses
- 2017
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Ingår i: Optical materials (Amsterdam). - Amsterdam : Elsevier. - 0925-3467 .- 1873-1252. ; 69, s. 134-140
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Tidskriftsartikel (refereegranskat)abstract
- Monolithic silica sol-gel glasses doped with platinum(II) acetylide complexes possessing respectively four or six phenylacetylene units (PE2-CH2OH and PE3-CH2OH) in combination with various concentrations of spherical and bipyramidal gold nanoparticles (AuNPs) known to enhance non-linear optical absorption, were prepared and polished to high optical quality. The non-linear absorption of the glasses was measured and compared to glasses doped solely with AuNPs, a platinum(II) acetylide with shorter delocalized structure, or combinations of both. At 532 nm excitation wavelength the chromophore inhibited the non-linear scattering previously found for glasses only doped with AuNPs. The measured non-linear absorption was attributed to reverse saturable absorption from the chromophore, as previously reported for PE2-CH2OH/AuNP glasses. At 600 nm strong nonlinear absorption was observed for the PE3-CH2OH/AuNPs glasses, also attributed to reverse saturable absorption. But contrary to previous findings for PE2-CH2OH/AuNPs, no distinct enhancement of the non-linear absorption for PE3-CH2OH/AuNPs was observed. A numerical population model for PE3-CH2OH was used to give a qualitative explanation of this difference. A stronger linear absorption in PE3-CH2OH would cause the highly absorbing triplet state to populate quicker during the leading edge of the laser pulse and this would in turn reduce the influence from two-photon absorption enhancement from AuNPs.
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| 16. |
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| 17. |
- Parola, S., et al.
(författare)
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Hybrid materials for non linear absorption
- 2005
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Ingår i: Nonlinear Optical Transmission and Multiphoton Processes in Organics III. - : SPIE - International Society for Optical Engineering. ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- Alkynyl platinum derivatives and thiacalixarenes were trapped in solid transparent matrices prepared by the sol-gel process. By using functionalyzed silicon alkoxides, molecular species were grafted to the gel matrix giving a high doping concentration and chemically stable materials. In this communication we present broadband optical limiting performance in the visible wavelength region observed in the prepared materials.
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| 18. |
- 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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