Probabilistic computing with voltage-controlled dynamics in magnetic tunnel junctions

Probabilistic (p-) computing is a physics-based approach to addressing computational problems which are difficult to solve by conventional von Neumann computers. A key requirement for p-computing is the realization of fast, compact, and energy-efficient probabilistic bits. Stochastic magnetic tunnel junctions (MTJs) with low energy barriers, where the relative dwell time in each state is controlled by current, have been proposed as a candidate to implement p-bits. This approach presents challenges due to the need for precise control of a small energy barrier across large numbers of MTJs, and due to the need for an analog control signal. Here we demonstrate an alternative p-bit design based on perpendicular MTJs that uses the voltage-controlled magnetic anisotropy (VCMA) effect to create the random state of a p-bit on demand. The MTJs are stable (i.e. have large energy barriers) in the absence of voltage, and VCMA-induced dynamics are used to generate random numbers in less than 10 ns/bit. We then show a compact method of implementing p-bits by using VC-MTJs without a bias current. As a demonstration of the feasibility of the proposed p-bits and high quality of the generated random numbers, we solve up to 40 bit integer factorization problems using experimental bit-streams generated by VC-MTJs. Our proposal can impact the development of p-computers, both by supporting a fully spintronic implementation of a p-bit, and alternatively, by enabling true random number generation at low cost for ultralow-power and compact p-computers implemented in complementary metal-oxide semiconductor chips.

Bisphosphonate-related osteonecrosis of the jaws and dental surgery procedures in children and young people with osteogenesis imperfecta: A systematic review

BACKGROUND

Bisphosphonates (BPs) contrast the bone fragility and improve bone density in some metastatic cancers and bone diseases, such as Osteogenesis Imperfecta (OI). BPs use has been associated with osteonecrosis of the jaws (BRONJs) in adults needing for invasive dental procedures.

AIM

To conduct a systematic review on BRONJ occurrence after dental surgery in paediatric population under BPs therapy for OI, so as to identify the pre-surgical protocols adopted.

DESIGN

According to PRISMA guidelines, Pubmed, Web of Science (WoS) and Cochrane were investigated on September 2018, and re-checked on July 2019. Inclusion criteria were English-language papers on children/young adults (until 24 years old) reporting dental/oral surgery procedures.

RESULTS

Totally, 60 articles were found. After title/abstract reviews and duplicates exclusion, 22 eligible titles underwent full-text evaluation. Finally, 10 studies were included.

CONCLUSIONS

The lack of BRONJ occurrence in paediatric population suffering OI and treated with BPs, was confirmed, but the reasons are still debated, being the BPs therapies and the surgical strategies various and not standardized. Longitudinal studies should evaluate what happens to those former children once adult, to evaluate the delayed BRONJs onset associated with the occurrence of comorbidities during the adulthood.

Abaloparatide for the treatment of postmenopausal osteoporosis

Abaloparatide is a synthetic 34-amino acid peptide analogue of the 1-34 portion of the human parathyroid hormone-related protein (PTHrP). It has been approved in the U.S. for the treatment of postmenopausal women with osteoporosis at a high risk for fracture. Abaloparatide is an anabolic agent and it seems to have a potent anabolic activity with reduced effects on bone resorption. It reduces the risk of vertebral and nonvertebral fractures, major osteoporotic fractures and clinical fractures, with a significant improvement in bone mineral density at femoral neck, total hip and lumbar spine. In this article we summarize the development of the abaloparatide molecule and preclinical and clinical studies published so far. Results from clinical trials indicate that abaloparatide may become an important option for the anabolic treatment of postmenopausal osteoporosis.