Searching for solar-like oscillations in pre-main sequence stars using APOLLO

In recent years, our understanding of solar-like oscillations from main sequence to red giant stars has improved dramatically thanks to pristine data collected from space telescopes. One of the remaining open questions focuses around the observational identification of solar-like oscillations in pre-main sequence stars. We aim to develop an improved method to search for solar-like oscillations in pre-main sequence stars and apply it to data collected by the Kepler K2 mission. Our software APOLLO includes a novel way to detect low signal-to-noise ratio solar like oscillations in the presence of a high background level. By calibrating our method using known solar-like oscillators from the main Kepler mission, we apply it to T Tauri stars observed by Kepler K2 and identify several candidate pre-main sequence solar-like oscillators. We find that our method is robust even when applied to time-series of observational lengths as short as those obtained with the TESS satellite in one sector. We identify EPIC 205375290 as a possible candidate for solar-like oscillations in a pre-main sequence star with $\nu_\mathrm{max} \simeq 242\,\mu$Hz. We also derive EPIC 205375290's fundamental parameters to be $T_\mathrm{eff}$ = 3670$\pm$180 K, log $g$ = 3.85$\pm$0.3, $v$sin$i$ = 8 $\pm$ 1 km s$^{-1}$, and about solar metallicity from a high-resolution spectrum obtained from the Keck archive.Comment: 14 pages, 13 figure

Events: Modellierungen und Schnittstellen

Abstract für das Konferenzpanel "Events: Modellierungen und Schnittstellen", DHd202

Artificial coherent states of light by multi-photon interference in a single-photon stream

Coherent optical states consist of a quantum superposition of different photon number (Fock) states, but because they do not form an orthogonal basis, no photon number states can be obtained from it by linear optics. Here we demonstrate the reverse, by manipulating a random continuous single-photon stream using quantum interference in an optical Sagnac loop, we create engineered quantum states of light with tunable photon statistics, including approximate weak coherent states. We demonstrate this experimentally using a true single-photon stream produced by a semiconductor quantum dot in an optical microcavity, and show that we can obtain light with $g^{(2)}(0)\rightarrow1$ in agreement with our theory, which can only be explained by quantum interference of at least 3 photons. The produced artificial light states are, however, much more complex than coherent states, containing quantum entanglement of photons, making them a resource for multi-photon entanglement.Comment: 6 pages + supplemental materia

YY1 haploinsufficiency causes an intellectual disability syndrome featuring transcriptional and chromatin dysfunction

Yin and yang 1 (YY1) is a well-known zinc-finger transcription factor with crucial roles in normal development and malignancy. YY1 acts both as a repressor and as an activator of gene expression. We have identified 23 individuals with de novo mutations or deletions of YY1 and phenotypic features that define a syndrome of cognitive impairment, behavioral alterations, intrauterine growth restriction, feeding problems, and various congenital malformations. Our combined clinical and molecular data define "YY1 syndrome" as a haploinsufficiency syndrome. Through immunoprecipitation of YY1-bound chromatin from affected individuals' cells with antibodies recognizing both ends of the protein, we show that YY1 deletions and missense mutations lead to a global loss of YY1 binding with a preferential retention at high-occupancy sites. Finally, we uncover a widespread loss of H3K27 acetylation in particular on the YY1-bound enhancers, underscoring a crucial role for YY1 in enhancer regulation. Collectively, these results define a clinical syndrome caused by haploinsufficiency of YY1 through dysregulation of key transcriptional regulators.Michele Gabriele, Anneke T. Vulto-van Silfhout, Pierre-Luc Germain, Alessandro Vitriolo, Raman Kumar, Evelyn Douglas, Eric Haan, Kenjiro Kosaki, Toshiki Takenouchi, Anita Rauch, Katharina Steindl, Eirik Frengen, Doriana Misceo, Christeen Ramane J. Pedurupillay, Petter Stromme, Jill A. Rosenfeld, Yunru Shao, William J. Craigen, Christian P. Schaaf, David Rodriguez-Buritica, Laura Farach, Jennifer Friedman, Perla Thulin, Scott D. McLean, Kimberly M. Nugent, Jenny Morton, Jillian Nicholl, Joris Andrieux, Asbjørg Stray-Pedersen, Pascal Chambon, Sophie Patrier, Sally A. Lynch, Susanne Kjaergaard, Pernille M. Tørring, Charlotte Brasch-Andersen, Anne Ronan, Arie van Haeringen, Peter J. Anderson, Zöe Powis, Han G. Brunner, Rolph Pfundt, Janneke H.M. Schuurs-Hoeijmakers, Bregje W.M. van Bon, Stefan Lelieveld, Christian Gilissen, Willy M. Nillesen, Lisenka E.L.M. Vissers, Jozef Gecz, David A. Koolen, Giuseppe Testa, Bert B.A. de Vrie

Catalogue of BRITE-Constellation targets I. Fields 1 to 14 (November 2013 - April 2016)

The BRIght Target Explorer (BRITE) mission collects photometric time series in two passbands aiming to investigate stellar structure and evolution. Since their launches in the years 2013 and 2014, the constellation of five BRITE nano-satellites has observed a total of more than 700 individual bright stars in 64 fields. Some targets have been observed multiple times. Thus, the total time base of the data sets acquired for those stars can be as long as nine years. Our aim is to provide a complete description of ready-to-use BRITE data, to show the scientific potential of the BRITE-Constellation data by identifying the most interesting targets, and to demonstrate and encourage how scientists can use these data in their research. We apply a decorrelation process to the automatically reduced BRITE-Constellation data to correct for instrumental effects. We perform a statistical analysis of the light curves obtained for the 300 stars observed in the first 14 fields during the first ~2.5 years of the mission. We also perform cross-identification with the International Variable Star Index. We present the data obtained by the BRITE-Constellation mission in the first 14 fields it observed from November 2013 to April 2016. We also describe the properties of the data for these fields and the 300 stars observed in them. Using these data, we detected variability in 64% of the presented sample of stars. Sixty-four stars or 21.3% of the sample have not yet been identified as variable in the literature and their data have not been analysed in detail. They can therefore provide valuable scientific material for further research. All data are made publicly available through the BRITE Public Data Archive and the Canadian Astronomy Data Centre.Comment: accepted by Astronomy & Astrophysics, 13 pages main text, 22 pages of appendi

The employment distribution and the creation of financial dependence

A fall in national income has varied consequences for the working population: some carry on working as normal, others become unemployed. Those excluded from work lose their main income source and must usually rely on public welfare, entering a financial dependence created endogenously as the economy adjusts. The current paper examines this induced financial dependence and its implications within a Post Keynesian model. A skewed employment distribution forces higher transfer payments than would occur if employment was distributed more evenly. The additional expenditures help to sustain profitability, so it is in the collective interest of employers and profit recipients to concentrate unemployment in a subset of the working population

MED27 Variants Cause Developmental Delay, Dystonia, and Cerebellar Hypoplasia

The Mediator multiprotein complex functions as a regulator of RNA polymerase II-catalyzed gene transcription. In this study, exome sequencing detected biallelic putative disease-causing variants in MED27, encoding Mediator complex subunit 27, in 16 patients from 11 families with a novel neurodevelopmental syndrome. Patient phenotypes are highly homogeneous, including global developmental delay, intellectual disability, axial hypotonia with distal spasticity, dystonic movements, and cerebellar hypoplasia. Seizures and cataracts were noted in severely affected individuals. Identification of multiple patients with biallelic MED27 variants supports the critical role of MED27 in normal human neural development, particularly for the cerebellum. ANN NEUROL 2021Peer reviewe