30 research outputs found
BK Lyncis: The Oldest Old Nova?... And a Bellwether for Cataclysmic-Variable Evolution
We summarize the results of a 20-year campaign to study the light curves of
BK Lyncis, a nova-like star strangely located below the 2-3 hour orbital period
gap in the family of cataclysmic variables. Two apparent "superhumps" dominate
the nightly light curves - with periods 4.6% longer, and 3.0% shorter, than
P_orb. The first appears to be associated with the star's brighter states
(V~14), while the second appears to be present throughout and becomes very
dominant in the low state (V~15.7).
Starting in the year 2005, the star's light curve became indistinguishable
from that of a dwarf nova - in particular, that of the ER UMa subclass.
Reviewing all the star's oddities, we speculate: (a) BK Lyn is the remnant of
the probable nova on 30 December 101, and (b) it has been fading ever since,
but has taken ~2000 years for the accretion rate to drop sufficiently to permit
dwarf-nova eruptions. If such behavior is common, it can explain other puzzles
of CV evolution. One: why the ER UMa class even exists (because all members can
be remnants of recent novae). Two: why ER UMa stars and short-period novalikes
are rare (because their lifetimes, which are essentially cooling times, are
short). Three: why short-period novae all decline to luminosity states far
above their true quiescence (because they're just getting started in their
postnova cooling). Four: why the orbital periods, accretion rates, and
white-dwarf temperatures of short-period CVs are somewhat too large to arise
purely from the effects of gravitational radiation (because the unexpectedly
long interval of enhanced postnova brightness boosts the mean mass-transfer
rate). These are substantial rewards in return for one investment of
hypothesis: that the second parameter in CV evolution, besides P_orb, is time
since the last classical-nova eruption.Comment: PDF, 46 pages, 4 tables, 10 figures; in preparation; more info at
http://cbastro.org
Intronic ATTTC repeat expansions in STARD7 in familial adult myoclonic epilepsy linked to chromosome 2
Familial Adult Myoclonic Epilepsy (FAME) is characterised by cortical myoclonic tremor
usually from the second decade of life and overt myoclonic or generalised tonic-clonic seizures.
Four independent loci have been implicated in FAME on chromosomes (chr) 2, 3, 5
and 8. Using whole genome sequencing and repeat primed PCR, we provide evidence that
chr2-linked FAME (FAME2) is caused by an expansion of an ATTTC pentamer within the first
intron of STARD7. The ATTTC expansions segregate in 158/158 individuals typically affected
by FAME from 22 pedigrees including 16 previously reported families recruited worldwide.
RNA sequencing from patient derived fibroblasts shows no accumulation of the AUUUU or
AUUUC repeat sequences and STARD7 gene expression is not affected. These data, in
combination with other genes bearing similar mutations that have been implicated in FAME,
suggest ATTTC expansions may cause this disorder, irrespective of the genomic locus
involvedSupplementary Information:
Supplementary Data 1;
Supplementary Data 2;
Reporting Summary.NHMRC;
Women’s and Children’s Hospital Research Foundation;
Muir Maxwell Trust;
Epilepsy Society;
The European Fund for Regional Development;
The province of Friesland, Dystonia Medical Research Foundation;
Stichting Wetenschapsfonds Dystonie Vereniging;
Fonds Psychische Gezondheid;
Phelps Stichting;
The Italian Ministry of Health;
Istituto Superiore di SanitĂ , Italy;
Undiagnosed Disease Network Italy;
The Fondation maladies rares, University Hospital Essen and
UK Department of Health’s NIHR.https://www.nature.com/ncommspm2020Neurolog
Heterozygous Variants in KMT2E Cause a Spectrum of Neurodevelopmental Disorders and Epilepsy.
We delineate a KMT2E-related neurodevelopmental disorder on the basis of 38 individuals in 36 families. This study includes 31 distinct heterozygous variants in KMT2E (28 ascertained from Matchmaker Exchange and three previously reported), and four individuals with chromosome 7q22.2-22.23 microdeletions encompassing KMT2E (one previously reported). Almost all variants occurred de novo, and most were truncating. Most affected individuals with protein-truncating variants presented with mild intellectual disability. One-quarter of individuals met criteria for autism. Additional common features include macrocephaly, hypotonia, functional gastrointestinal abnormalities, and a subtle facial gestalt. Epilepsy was present in about one-fifth of individuals with truncating variants and was responsive to treatment with anti-epileptic medications in almost all. More than 70% of the individuals were male, and expressivity was variable by sex; epilepsy was more common in females and autism more common in males. The four individuals with microdeletions encompassing KMT2E generally presented similarly to those with truncating variants, but the degree of developmental delay was greater. The group of four individuals with missense variants in KMT2E presented with the most severe developmental delays. Epilepsy was present in all individuals with missense variants, often manifesting as treatment-resistant infantile epileptic encephalopathy. Microcephaly was also common in this group. Haploinsufficiency versus gain-of-function or dominant-negative effects specific to these missense variants in KMT2E might explain this divergence in phenotype, but requires independent validation. Disruptive variants in KMT2E are an under-recognized cause of neurodevelopmental abnormalities
The installation and ongoing commissioning of the MATISSE mid-infrared interferometer at the ESO Very Large Telescope Observatory
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