Precise characterization of a corridor-shaped structure in Khufu's Pyramid by observation of cosmic-ray muons.

Khufu's Pyramid is one of the largest archaeological monument all over the world, which still holds many mysteries. In 2016 and 2017, the ScanPyramids team reported on several discoveries of previously unknown voids by cosmic-ray muon radiography that is a non-destructive technique ideal for the investigation of large-scale structures. Among these discoveries, a corridor-shaped structure has been observed behind the so-called Chevron zone on the North face, with a length of at least 5 meters. A dedicated study of this structure was thus necessary to better understand its function in relation with the enigmatic architectural role of this Chevron. Here we report on new measurements of excellent sensitivity obtained with nuclear emulsion films from Nagoya University and gaseous detectors from CEA, revealing a structure of about 9 m length with a transverse section of about 2.0 m by 2.0 m.

Discovery of a big void in Khufu's Pyramid by observation of cosmic-ray muons.

The Great Pyramid, or Khufu's Pyramid, was built on the Giza plateau in Egypt during the fourth dynasty by the pharaoh Khufu (Cheops), who reigned from 2509 bc to 2483 bc. Despite being one of the oldest and largest monuments on Earth, there is no consensus about how it was built. To understand its internal structure better, we imaged the pyramid using muons, which are by-products of cosmic rays that are only partially absorbed by stone. The resulting cosmic-ray muon radiography allows us to visualize the known and any unknown voids in the pyramid in a non-invasive way. Here we report the discovery of a large void (with a cross-section similar to that of the Grand Gallery and a minimum length of 30 metres) situated above the Grand Gallery. This constitutes the first major inner structure found in the Great Pyramid since the nineteenth century. The void, named ScanPyramids' Big Void, was first observed with nuclear emulsion films installed in the Queen's chamber, then confirmed with scintillator hodoscopes set up in the same chamber and finally re-confirmed with gas detectors outside the pyramid. This large void has therefore been detected with high confidence by three different muon detection technologies and three independent analyses. These results constitute a breakthrough for the understanding of the internal structure of Khufu's Pyramid. Although there is currently no information about the intended purpose of this void, these findings show how modern particle physics can shed new light on the world's archaeological heritage.

Anti-MuSK myasthenia gravis with prolonged remission.

Myasthenia gravis (MG) with antibodies against muscle-specific tyrosine kinase (MuSK) is a rare disorder of neuromuscular transmission affecting preferentially bulbar, neck and respiratory muscles. We report the case of a 22-year-old man who presented with diplopia on lateral gaze to both sides, facial diplegia, nasal dysarthria and dysphagia. Repetitive nerve stimulation of the trapezius and orbicularis oculi muscles showed amplitude decrements of 19% and 41% respectively supporting the diagnosis of myasthenia gravis. MUsK antibodies were positive. Corticosteroids were introduced and then tapered and discontinued at 6 months after initiation. The patient remained in remission and asymptomatic for 4 years without ongoing treatment or prior treatment with rituximab after this first relapse of MuSK-MG. MuSK- MG is considered a hard-to-treat condition and patients generally remain dependent on immunosuppression or prior treatment with rituximab. Our observation highlights that patients with MuSK-MG can have a benign course and that continued immunosuppressive or immunomodulatory therapy may not always be required.

A non-DM1, non-DM2 multisystem myotonic disorder with frontotemporal dementia: phenotype and suggestive mapping of the DM3 locus to chromosome 15q21-24.

The majority of proximal myotonic myopathy syndromes reported so far have been related to the myotonic dystrophy (DM) type 2 (DM2) mutation, an expanded (CCTG)n repeat in the ZNF9 gene. Here, we describe the phenotype and the histological features in muscle and brain of the first large pedigree with a non-myotonic dystrophy type 1 (DM1) non-DM2 multisystem myotonic disorder associated with severe frontotemporal dementia. Thirty individuals from three generations underwent detailed neurological, neuropsychological, electrophysiological, brain imaging and molecular analyses. Ten of them had proximal muscle weakness at onset, clinical/electrical myotonia and DM-type cataracts. The mean age at onset was 46.7 +/- 12.6 years (range: 32-69). Dementia was observed later in the course of the disease. On muscle biopsies, rare nuclear clumps, rimmed vacuoles and small angulated type 1 and type 2 fibres were seen early in the disease. They were replaced by fibrous adipose tissue at later stages. Immunohistochemical analysis of myosin heavy chain isoforms showed no selective fibre type atrophy-both type 1 and type 2 fibres being affected. Cortical atrophy without white matter lesions was seen on brain MRI. A brain single photon emission computed tomography (SPECT) study revealed marked frontotemporal hypoperfusion. Post-mortem examination of the brains of two patients showing prominent frontotemporal spongiosis, neuronal loss and rare neuronal and glial tau inclusions suggested frontotemporal dementia. Western blot analyses of the tau protein showed a triplet of isoforms (60, 64 and 69 kDa) in neocortical areas, and a doublet (64 and 69 kDa) in subcortical areas that distinguish our myotonic disorder from other's myotonic dystrophies. Molecular analyses failed to detect a repeat expansion in the DMPK and ZNF9 genes excluding both DM1 and DM2, whereas a genome-wide linkage analysis strongly suggested a linkage to chromosome 15q21-24. This previously unreported multisystem myotonic disorder including findings resembling DM1, DM2 and frontotemporal dementia provides further evidence of the clinical and genetic heterogeneity of the myotonic dystrophies. We propose to designate this disease myotonic dystrophy type 3, DM3.