| 1. |
- Montofre, Daniel, 1989, et al.
(författare)
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A broadband and dual-polarization single-layer dichroic filter for applications in Sub-THz range
- 2022
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Ingår i: 32nd International Symposium of Space Terahertz Technology, ISSTT 2022.
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Konferensbidrag (refereegranskat)abstract
- In this work we report the design of a single-layer all-metall dichroic filter with an improved spectral response at non-normal beam incidence and nearly equal performance for both polarizations. The dichroic is intended to be employed for dual-frequency receivers. Since the dichroic is produced purely from metal it facilitates its use at cryogenic temperatures. Therefore, the contribution to the system noise is minimized. The dichroic design concept demonstrated a measured transmission of electromagnetic radiation of 85-90% for both polarizations in the range of 35-50 GHz (37% fractional bandwidth). The measurements were performed at room temperature. The spectral properties of the dichroic have been optimized by modeling in 3D FEM simulation software.
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| 2. |
- Roy, Jean-Claude, et al.
(författare)
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The ORS Vertebrates of Spitsbergen (Svalbard)
- 2010
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Ingår i: Résumés. ; , s. 223-223
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In the Arctic, Spitsbergen (Svalbard archipelago) comprises a Caledonian metamorphic basement structured around 420 Ma, cut by faults that demarcate a sedimentary, NS graben, filled up by siliclastic detrital series of Old Red Sandstone facies (ca. 418 - ca. 326 Ma), with a lateral cumulative thickness of 6300 to more than 10,800 meters. The latter yields a particularly abundant fauna of early fishes, which are the main guide fossils for stratigraphic purposes (Agnatha, Placodermi and Crossopterygii). These sediments are faulted and folded, and disconformably overlapped by the unfolded, marine Carboniferous - Permian carbonate platform. The Old Red Sandstone of Spitsbergen is a reference for all the contemporaneous series of the ORS Continent. However, since the outcrops were hitherto discontinuous in the Polar zone, the stratigraphic correlations were difficult to establish, and the definition of the lithostratigraphic units are still discussed. This region is one of the least studied as for paleontology and stratigraphy, even if several fossil collections and partial field mappings have been made, notably in 1939 with the Anglo-Norwegian-Swedish palaeontological expedition, and in 1969 with the French CNRS-MNHN expedition, later completed by the Russian and German works (Murasov and Mokin 1976, 1979; Schweitzer, 1999). Since the acceleration of the melting of the glaciers and of the ice-cap, the gradual continental rise by glacioisostasy and the erosion by torrents and the tide cause incisions in the moraines, and new outcrops appear. In the framework of a collaboration with the Norsk Polarinstitutt, our field teams could visit some of them, such as LGGST - Chorowicz 1986 to 1994, Roy 1999, CAST 401 IFRTP - ipev 2002 and 2003, Roy 2008, and SPITZ P3 1005 ipev 2010, and the stratigraphical correlation of the nunataks is in progress. Palaeontology, geology, geophysical and geochimical geochronology show that, in Spitsbergen, the deposition of the ORS began in Late Silurian (?Pridoli) times and continued in the Devonian and Carboniferous until the beginning of the late Mississipian. The new information we now have, thanks to studies led in the framework of the International Geologic Correlation Programme 328 (Blieck and Turner 2000) and IGCP 406 Programme, 'Circum Arctic Lower - Middle Paleozoic Vertebrate Palaeontology and Biostratigraphy', with H. Blom (Uppsala) and V. Talimaa (Vilnius), lead us to consider the sedimentation of the graben and its tectonic behaviour as an essential source of data for understanding the natural history of the Arctic: the consequences of the closure of the Iapetus ocean and the dismantling of the Caledonian chain. The bio- and litho- stratigraphy begins to be accurately known, notably thanks to the vertebrate-based biozones (Agnatha, Placodermi and Crossopterygii); a work that was been initiated by Daniel Goujet (1984) and continued by the research team on vertebrate fossils of Spitsbergen (Blieck, 1982, 1984; Goujet, 1984; Janvier 1985; Blieck et al., 1987; Clément, 2001; Pernegre, 2004). If some of these vertebrates seem endemic to Spitsbergen and to the Arctic, they are closely connected to marine species of global distribution, notably with Australian species.
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| 3. |
- Abbasi, Rasha, et al.
(författare)
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IceCube search for neutrinos from GRB 221009A
- 2023
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Ingår i: Proceedings of 38th International Cosmic Ray Conference (ICRC 2023). - : Sissa Medialab Srl.
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Konferensbidrag (refereegranskat)abstract
- GRB 221009A is the brightest Gamma Ray Burst (GRB) ever observed. The observed extremelyhigh flux of high and very-high-energy photons provide a unique opportunity to probe the predictedneutrino counterpart to the electromagnetic emission. We have used a variety of methods to searchfor neutrinos in coincidence with the GRB over several time windows during the precursor, promptand afterglow phases of the GRB. MeV scale neutrinos are studied using photo-multiplier ratescalers which are normally used to search for galactic core-collapse supernovae neutrinos. GeVneutrinos are searched starting with DeepCore triggers. These events don’t have directionallocalization, but instead can indicate an excess in the rate of events. 10 GeV - 1 TeV and >TeVneutrinos are searched using traditional neutrino point source methods which take into accountthe direction and time of events with DeepCore and the entire IceCube detector respectively. The>TeV results include both a fast-response analysis conducted by IceCube in real-time with timewindows of T0 − 1 to T0 + 2 hours and T0 ± 1 day around the time of GRB 221009A, as well asan offline analysis with 3 new time windows up to a time window of T0 − 1 to T0 + 14 days, thelongest time period we consider. The combination of observations by IceCube covers 9 ordersof magnitude in neutrino energy, from MeV to PeV, placing upper limits across the range forpredicted neutrino emission.
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| 4. |
- Belitsky, Victor, 1955, et al.
(författare)
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ALMA Band 2 Cold Cartridge Assembly Design
- 2022
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Ingår i: 32nd International Symposium of Space Terahertz Technology, ISSTT 2022.
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Konferensbidrag (refereegranskat)abstract
- As part of the ALMA development, we present the design of the ALMA Band 2 Cold Cartridge Assembly (CCA). The Band 2 is the last band that completes the suit of the 10 receiver channels of ALMA. The originally planned ALMA Band 2 receiver cartridge should cover the RF band of 67 - -90 GHz. The recent progress in technology, optics, OMT design and mm-wave amplifiers, however allowed to implement receiver that has an extended RF band up to 116 GHz. Furthermore, the Band 2 receiver pursues 2SB layout and provides 4-18 GHz IF band for two sidebands in a dual-polarization configuration. Here, we describe the design of the Band 2 CCA that includes optics, amplifier assembly, internal RF transport, mechanics and cryogenics. The downconverter part and performances are described elsewhere.
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| 5. |
- Cumbal, Ronald, et al.
(författare)
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Shaping unbalanced multi-party interactions through adaptive robot backchannels
- 2022
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Ingår i: <em>IVA 2022 - Proceedings of the 22nd ACM International Conference on Intelligent Virtual Agents</em>. - : Association for Computing Machinery, Inc.
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Konferensbidrag (refereegranskat)abstract
- Non-verbal cues used in human communication have shown to be efficient in shaping speaking interactions. When applied to virtual agents or social robots, results imply that a similar effect is expected in dyad settings. In this study, we explore how encouraging, vocal and non-vocal, backchannels can stimulate speaking participation in a game-based multi-party interaction, where unbalanced contribution is expected. We design the study using a social robot, taking part in a language game with native speakers and language learners, to evaluate how an adaptive generation of backchannels, that targets the least speaking participant to encourage more speaking contribution, affects the group and individual participant's behavior. We report results from experiments with 30 subjects divided in pairs assigned to the adaptive (encouraging) and (neutral) control condition. Our results show that the speaking participation of the least active speaker increases significantly when the robot uses an adaptive backchanneling strategy. At the same time, the participation of the more active speaker slightly decreases, which causes the combined speaking time of both participants to be similar between the Control and Experimental conditions. The adaptive strategy further leads to a 50% decrease in the difference in speaker shares between the two participants (indicating a more balanced participation) compared to the Control condition. However, this distribution between speaker ratios is not significantly different from the Control.
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| 6. |
- Dupret, Vincent, 1977-, et al.
(författare)
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Being Romundina stellina Ørvig, 1975 (Vertebrate, Placodermi, Acanthothoraci) : itracranial anatomy of one of the deepest gnathostomes revealed by synchrotron tomograpy in phase contrast protocole
- 2012
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Konferensbidrag (refereegranskat)abstract
- Dans la peau de Romundina stellina Ørvig, 1975 (Vertebrata, Placodermi, Acanthothoraci)Anatomie crânienne d'un des premiers gnathostomes révélée par tomographie synchrotron en contraste de phase Being Romundina stellina Ørvig, 1975 (Vertebrata, Placodermi, Acanthothoraci)Intracranial anatomy of one of the deepest gnathostomes revealed by synchrotron tomography in phase contrast protocole The acanthothoracid placoderms (armored fishes) are the most basal and primitive gnathostomes (jawed vertebrates; 1). However, their endocranial morphology is poorly understood, and only one genus (Brindabellaspis) has been described thoroughly (2).Here we present the 3D reconstruction of a subcomplete skull of Romundina stellina Ørvig, 3, from the Lochkovian of Prince of Wales Island, Canadian Arctic Archipelago. The specimen was imaged in 3D with propagation phase contrast microtomography (4) on the ID19 beamline of the ESRF, using a 7.45 µm isotropic voxel size.Most features are properly preserved and most of the missing structures can be virtually rebuilt by symmetry. Another advantage of this virtual approach is the possibility of connecting with certainty all the external foramina to the blood and nerve canals and the central/internal structures, and hence to identify accurate homologies without destroying the specimen. Ørvig’s original assumptions can now be checked with confidence.The vasculature of the dermal bones, rendered in detail, allowed a better understanding of plate growth. It permits the visualization of dermal bone establishment over perichondral bone (5).The high level of details of this model reveals that between the trigeminal and vagus nerve (and the inner ears), the perichondral bone wrapping the endocranial cavity shows a “lace” pattern, unknown so far in vertebrates (presumably because of the lack of data). The significance of this character is unclear, but it is definitely not an artifact of taphonomy or scanning. References1 Janvier, P. Early Vertebrates. Clarendon Press edn, Vol. 1 (Oxford Science Publications, 1996).2 Young, G. C. A new Early Devonian placoderm from New South Wales, Australia, with a discussion of placoderm phylogeny. Palaeontographica (A) 167, 10–76 (1980).3 Ørvig, T. Description, with special reference to the dermal skeleton, of a new Radotinid arthrodire from the Gedinnian of Arctic Canada. Extrait des Colloques internationaux du Centre National de la Recherche Scientifique - Problèmes actuels de Paléontologie - Evolution des Vertébrés 218, 41–71 (1975).4 Tafforeau, P. et al. Applications of X-ray synchrotron microtomography for non-destructive 3D studies of paleontological specimens. Applied Physics A - Materials Science & Processing 83, 195–202 (2006).5 Dupret, V., Sanchez, S., Goujet, D., Tafforeau, P. & Ahlberg, P. Bone vascularization and growth in placoderms (Vertebrata): the example of the premedian plate of Romundina stellina Ørvig, 1975 Comptes Rendus Palevol 9, 369–375 (2010).
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| 7. |
- Dupret, Vincent, 1977-, et al.
(författare)
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Fossil early vertebrates shed lights on the origin of the gnathostome face
- 2013
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Ingår i: Program and Abstracts of the 10th International Congress of Vertebrate Morphology. - Barcelona, Spain. ; , s. 245-245
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Konferensbidrag (refereegranskat)abstract
- Jawless cyclostomes and jawed gnathostomes show very different face patterns. Cyclostomes have a single median nasohypophysial duct, an anterior hypophysis and a short telencephalon, while gnathostomes have a pair of nasal sacs opening externally, a more posterior separate hypophysis open in the palate and a longer telencephalon.Embryonic processes differ as well. In cyclostomes, premandibular crest cells migrate forwards either side of the nasohypophysial placode to form the upper lip; in gnathostomes they migrate between the hypophysial and nasal placodes to form the trabecular region. Supraoptic neural crest remains posterior to the nasohypophysial duct in cyclostomes; it moves forward to create the nasal capsules in gnathostomes.Some fossil forms illustrate a transition between these two patterns.The jawless galeaspid Shuyu (-430 Ma) has a nasohypophysial duct, short telencephalon, and anteriorly oriented hypophysis, but the paired nasal sacs and hypophysis are separated by a rudimentary trabecula.The jawed primitive placoderm Romundina (-415 Ma) shows a cranial cavity reminiscent of that of Shuyu (anteriorly directed hypophysis, very short telencephalon). The trabecular region is long and wide, the nasal capsule is small and located far behind the tip of the snout but just in front of the orbits. We interpret these features as uniquely primitive among gnathostomes. The premandibular crest of Romundina formed a trabecular region extending as anteriorly as the tip of the snout (like in extant cyclostome and the fossil Shuyu). The position of the nasal capsule suggests that the supraoptic crest had not migrated forwards.We suggest that the evolutionary sequence for the creation of the extant gnathostome face from a cyclostome pattern involved 1) separation of the nasal and hypophysial placodes (galeaspids), 2) loss of the nasohypophysial duct (placoderms), and 3) lengthening of the telencephalon and the migration of the nasal capsules to the snout tip.
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| 8. |
- Dupret, Vincent, 1977-, et al.
(författare)
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Fossils of early vertebrates and the evolution of the gnathostome face revealed by Synchrotron imaging
- 2013
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Ingår i: Programme and Abstracts. - Edinburgh, U.K.. ; , s. 21-21
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Konferensbidrag (refereegranskat)abstract
- Cyclostomes and gnathostomes have distinct face patterns. Cyclostomes possess a median nasohypophysial duct, an anterior hypophysis and a short telencephalon, contra gnathostomes possessing a pair of nasal sacs opening externally, a separate posterior hypophysis opening onto the palate and a long telencephalon. Embryonic development also differs. In cyclostomes, premandibular crest cells migrate forwards either side of the nasohypophysial placode, forming an upper lip; in gnathostomes they migrate between the hypophysial and nasal placodes forming the trabecular region. Supraoptic neural crest remains posterior to the nasohypophysial duct in cyclostomes but moves forward to create the nasal capsules in gnathostomes. Fossil stem gnathostomes illustrate a transitional sequence between these two patterns: 1) The galeaspid Shuyu (jawless stem gnathostome): nasohypophysial duct, short telencephalon, and anteriorly oriented hypophysis as in a cyclostome, but paired nasal sacs and hypophysis separated by a rudimentary trabecula. 2) The primitive placoderm Romundina (jawed stem gnathostome): short telencephalon, anteriorly directed hypophysis, trabecular region long and wide, nasal capsule located far behind the tip of the snout but just in front of the orbits. These features are interpreted as uniquely primitive among gnathostomes. The trabeculae of Romundina form an extensive precerebral region resembling the upper lip of extant cyclostomes and Shuyu. The position of the nasal capsule suggests that the supraoptic crest had not migrated forwards. 3) The arthrodire Kujdanowiapsis (a more derived placoderm): short telencephalon and vertically oriented hypophysis. The trabecula has been shortened anteriorly, making the nasal capsule terminal. These positional relationships are maintained in crown gnathostomes.
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| 9. |
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| 10. |
- Dupret, Vincent, 1977-, et al.
(författare)
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Intracranial anatomy of Romundina stellina Ørvig 1975 (Vertebrata, Placodermi, Acanthothoraci) revealed by phase contrast synchrotron imaging
- 2011
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Ingår i: Abstracts. ; , s. 6-6
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Acanthothoracid placoderms are considered amongst the most basal of primitive gnathostomes. However, their endocranial morphology is poorly understood, and only one genus (Brindabellaspis) has been described in detail. Here we present a synchrotrongenerated 3D reconstruction of a nearly complete skull of Romundina stellina, a taxon established in 1975 by the Norwegian-born Swedish palaeontologist Tor Ørvig based on remains from the Lochkovian (Lower Devonian) of Prince of Wales Island, Canadian Arctic Archipelago. The specimen was imaged with propagation phase contrast microtomography on the ID19 beamline of the ESRF, using a 7.45 µm isotropic voxel size. Most structural features of the fossil are very well preserved, allowing missing elements to be virtually rebuilt by symmetry. This permitted reconnection of the external foramina and blood vessel/nerve canals, and alignment of the central/internal structures. Expanding on Ørvig’s original interpretations, our virtual models show the vasculature of the skull bones, and indicate establishment of successive dermal over perichondral bone layers. The perichondral bone wrapping the endocranial cavity, in between the trigeminal and vagus nerve (and the inner ears), shows a “lace” pattern, which is otherwise unknown in vertebrates (presumably because of the lack of data). The significance of this trait is unclear but it is not an artifact of taphonomy or scanning.
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