657 research outputs found
Astrophysical neutrinos flavored with Beyond the Standard Model physics
We systematically study the allowed parameter space for the flavor
composition of astrophysical neutrinos measured at Earth, including beyond the
Standard Model theories at production, during propagation, and at detection.
One motivation is to illustrate the discrimination power of the next-generation
neutrino telescopes such as IceCube-Gen2. We identify several examples that
lead to potential deviations from the standard neutrino mixing expectation such
as significant sterile neutrino production at the source, effective operators
modifying the neutrino propagation at high energies, dark matter interactions
in neutrino propagation, or non-standard interactions in Earth matter.
IceCube-Gen2 can exclude about 90% of the allowed parameter space in these
cases, and hence will allow to efficiently test and discriminate models. More
detailed information can be obtained from additional observables such as the
energy-dependence of the effect, fraction of electron antineutrinos at the
Glashow resonance, or number of tau neutrino events.Comment: 21 pages, 9 figures, 3 tables, v2: references added, typos corrected,
conclusion unchanged, matches final version in PR
Machine learning applications for the study of AGN physical properties using photometric observations
We investigate the physical nature of Active Galactic Nuclei using machine
learning tools. We show that the redshift , the bolometric luminosity
, the central mass of the supermassive black hole ,
the Eddington ratio as well as the AGN class (obscured or
unobscured) can be reconstructed through multi-wavelength photometric
observations only. A Support Vector Regression (SVR) ML-model is trained on
7616 of spectroscopically observed AGN from the SPIDERS-AGN survey, previously
cross-matched with soft X-ray observations (from ROSAT or XMM), WISE
mid-infrared photometry, and optical photometry from SDSS filters. We
build a catalogue of 21364 AGN to be reconstructed with the trained SVR: for
9944 sources, we found archival redshift measurements. All AGN are classified
as either Type 1/2 using a Random Forest (RF) algorithm on a subset of known
sources. All known photometric measurement uncertainties are incorporated using
a simulation-based approach. We present the reconstructed catalogue of 21364
AGN with redshifts ranging from . estimations are made for
11420 new sources, with an outlier rate within 10%. Type 1/2 AGN can be
identified with respective efficiencies of 88% and 93%: the estimated
classification of all sources is given in the dataset. , , and values are given for 16907 new sources with their
estimated error. These results have been made publicly available. The release
of this catalogue will advance AGN studies by presenting key parameters of the
accretion history of 6 dex in luminosity over a wide range of . Similar
applications of ML techniques using photometric data only will be essential in
the future, with large datasets from eROSITA, JSWT and the VRO poised to be
released in the next decade.Comment: 20 pages, 24 figures, submitted to A&
Introducing the MeVCube concept: a CubeSat for MeV observations
Despite the impressive progress achieved both by X-ray and gamma-ray observatories in the last few decades, the energy range between ⌠200 keV and ⌠50 MeV remains poorly explored. COMPTEL, on-board the Compton Gamma-Ray Observatory (CGRO, 1991-2000), opened the MeV gamma-ray band as a new window to astronomy, performing the first all-sky survey in the energy range from 0.75 to 30 MeV. More than 20 years after the de-orbit of CGRO, no successor mission is yet operating. Over the past years many concepts have been proposed, for new observatories exploring different configurations and imaging techniques; a selection of the most recent ones includes AMEGO, ETCC, GECCO and COSI.
We propose here a novel concept for a Compton telescope based on the CubeSat standard, named MeVCube, with the advantages of small cost and relatively short development time. The scientific payload is based on two layers of pixelated Cadmium-Zinc-Telluride (CdZnTe) detectors, coupled with low-power read-out electronics (ASIC, VATA450.3). The performance of the read-out electronics and CdZnTe custom designed detectors have been measured extensively at DESY [1]. The performance of the telescope is accessed through simulations: despite a small effective area limited to a few cm2, MeVCube can reach an angular resolution of 1.5° and a sensitivity comparable to the one achieved by the last generation of large-scale satellites like COMPTEL and INTEGRAL. Combined with a large field-of-view and a moderate cost, MeVCube can be a powerful instrument for transient observations and searches of electromagnetic counterparts of gravitational wave events.Peer Reviewe
Introducing the MeVCube concept: a CubeSat for MeV observations
Despite the impressive progress achieved both by X-ray and gamma-ray
observatories in the last few decades, the energy range between
and remains poorly explored.
COMPTEL, on-board the Compton Gamma-Ray Observatory (CGRO, -),
opened the MeV gamma-ray band as a new window to astronomy, performing the
first all-sky survey in the energy range from to .
More than years after the de-orbit of CGRO, no successor mission is yet
operating. Over the past years many concepts have been proposed, for new
observatories exploring different configurations and imaging techniques; a
selection of the most recent ones includes AMEGO, ETCC, GECCO and COSI. We
propose here a novel concept for a Compton telescope based on the CubeSat
standard, named MeVCube, with the advantages of small cost and relatively short
development time. The scientific payload is based on two layers of pixelated
Cadmium-Zinc-Telluride (CdZnTe) detectors, coupled with low-power read-out
electronics (ASIC, VATA450.3). The performance of the read-out electronics and
CdZnTe custom designed detectors have been measured extensively at DESY. The
performance of the telescope is accessed through simulations: despite a small
effective area limited to a few , MeVCube can reach an angular
resolution of and a sensitivity comparable to the one achieved by
the last generation of large-scale satellites like COMPTEL and INTEGRAL.
Combined with a large field-of-view and a moderate cost, MeVCube can be a
powerful instrument for transient observations and searches of electromagnetic
counterparts of gravitational wave events
A preliminary phylogeny of Loasaceae subfam. Loasoideae (Angiospermae: Cornales) based on trnL(UAA) sequence data, with consequences for systematics and historical biogeography
AbstractThe phylogeny of Loasaceae subfam. Loasoideae is investigated with sequences of the chloroplast trnL(UAA) intron, all genera and infrageneric entities are included in the analysis. Loasaceae subfam. Loasoideae is monophyletic, and the two most speciose, and monophyletic, clades (which account for approximately 90% of the species total) are Nasa and the so-called Southern Andean Loasas (Blumenbachia, Caiophora, Loasa s.str., Scyphanthus), but the phylogeny of the remainder is not completely resolved. The data underscore a basal position for Chichicaste, Huidobria, Kissenia, and Klaprothieae (Xylopodia, Klaprothia, Plakothira). High bootstrap support values confirm the monophyly both of Klaprothieae and Presliophytum (when expanded to include Loasa ser. Malesherbioideae). Aosa and Blumenbachia are not resolved as monophyletic, but have clear morphological apomorphies. Within Nasa, âN. ser. Saccataeâ is paraphyletic, and âN. ser. Carunculataeâ is polyphyletic. However, the N. triphylla group in âN. ser. Saccataeâ is a well-supported monophyletic group, as is N. ser. Grandiflorae. âLoasaâ in its traditional circumscription is paraphyletic, but Loasa s.str. (L. ser. Macrospermae, L. ser. Deserticolae, L. ser. Floribundae) is monophyletic. The remainder of âLoasaâ (L. ser. Pinnatae, L. ser. Acaules, L. ser. Volubiles) is probably closely allied to the essentially Patagonian-High Andean group comprising also Scyphanthus and Caiophora. These findings are congruent with morphology and phytogeography. Nasa seems to have undergone its primary radiation at moderate elevations (1500â2500m) in the Andes of northern Peru (Amotape-Huancabamba Zone) and subsequently diversified into high elevations (above 4000m) of the tropical Central Andes. South Andean Loasas appear to have undergone their primary diversification in the southern temperate and mediterranean regions of Chile and Argentina, with a subsequent northwards expansion of Caiophora into the high elevations of the tropical Andes. Hummingbird pollination has evolved independently from melittophily in High Andean clades of Nasa and Caiophora
Specific targeting of human caspases using designed ankyrin repeat proteins
Caspases play important roles in cell death, differentiation, and proliferation. Due to their high homology, especially of the active site, specific targeting of a particular caspase using substrate analogues is very difficult. Although commercially available small molecules based on peptides are lacking high specificity due to overlapping cleavage motives between different caspases, they are often used as specific tools. We have selected designed ankyrin repeat proteins (DARPins) against human caspases 1-9 and identified high-affinity binders for the targeted caspases, except for caspase 4. Besides previously reported caspase-specific DARPins, we generated novel DARPins (D1.73, D5.15, D6.11, D8.1, D8.4, and D9.2) and confirmed specificity for caspases 1, 5, 6, and 8 using a subset of caspase family members. In addition, we solved the crystal structure of caspase 8 in complex with DARPin D8.4. This binder interacts with non-conserved residues on the large subunit, thereby explaining its specificity. Structural analysis of this and other previously published crystal structures of caspase/DARPin complexes depicts two general binding areas either involving active site forming loops or a surface area laterally at the large subunit of the enzyme. Both surface areas involve non-conserved surface residues of caspase
Rheology, dispersion, and cure kinetics of epoxy filled with amineâ and nonâfunctionalized reduced graphene oxide for composite manufacturing
This study evaluates the effect of plasma surface functionalization of reduced graphene oxide particles on the processing characteristics and homogeneity of dispersion of a bisphenol Aâ(epichlorhydrin) epoxy matrix and amineâbased hardener with varying weight fractions from 0.00 to 1.50âwt%. It was observed that amineâfunctionalized reduced graphene oxide leads to a more drastic viscosity increase of up to 18âfold of the uncured suspensions and that its presence influences the conversion rates of the curing reaction. Optical microscopy of thin sections and transmission electron microscopy analysis showed that a more homogeneous dispersion of the particles could be achieved especially at higher weight fractions by using an appropriate surface functionalization. This knowledge can be used to define suitable processing conditions for epoxies with amineâbased hardeners depending on the loading and functionalization of grapheneârelated particles
Mechanical bowel preparation and antimicrobial prophylaxis in elective colorectal surgery in Switzerlandâa survey
Background: The aim of this study was to assess the use of mechanical bowel preparation (MBP) and antimicrobial prophylaxis in elective colorectal surgery in Switzerland. Methods: Ninety-eight heads of surgical departments in Switzerland and 42 visceral surgeons in private practice were asked to answer an 18-item questionnaire in October 2008 about arguments in favor of or against MBP. The participants also indicated whether they use MBP and antimicrobial prophylaxis in colorectal surgery, and if so, what agents were used. Of the participants, 117/140 (83%) responded. Additional data were collected pertaining to the respondents' experience and work situation. Results: MBP was used significantly more often for rectal surgery than for left colonic resections (83% vs. 53%; pâ<â0.001) and more often for left than for right colonic resections (53% vs. 43%; pâ=â0.001), regardless of the open or laparoscopic approach. Younger surgeons and surgeons with a higher case load in colorectal surgery used MBP significantly less frequently in open right colonic resections. For MBP, cathartics were used in 90% of patients, and enemas were used in 10% of patients. Of the respondents, 37% considered MBP to be useful, even very useful. Based on the literature, because of introduction of fast-track protocols or for considerations of patient comfort, 86% of the respondents had changed the bowel preparation regime during the last 10years in terms of a reduction of the quantity of cathartics or restricted the indications for MBP. Antimicrobial prophylaxis was used by 100% of the respondents, 88% used a single prophylactic dose only, while 70% administered the antibiotics 30-59min before the incision. Most of the surgeons used second-generation cephalosporins in combination with metronidazole, and 24% changed the antibiotic agent or reduced the duration of administration of antibiotics during the last 10years. Conclusions: MBP is often used in open and laparoscopic rectal surgery, but not in right colonic resections. Scientific evidence regarding MBP has yielded a rethinking about rigorous bowel preparation regimes. As of now, surgeons in Switzerland are not yet unanimously ready to abandon MBP in elective colorectal surgery. In Switzerland, surgeons are influenced by the benefit of antimicrobial prophylaxis in colorectal surger
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