Exploring logic-in-memory architectures with skyrmion technology

L'abstract è presente nell'allegato / the abstract is in the attachmen

Simulation and Modeling of Racetrack Memories With VCMA Synchronization

The control of the motion of magnetic domains is of crucial interest for the development of several spintronic applications, such as high-density racetrack memories and domain wall logic. In these devices, domain wall manipulation can be achieved via pulsed currents or applying external fields. However, real-world applications require accurate signal synchronization systems, keeping limited the power budget. Up to now, geometrical restrictions in the magnetic wire, known as notches, were used to confine domain walls at the expense of high resolution of the fabrication process. The solution based on the Voltage-Controlled Magnetic Anisotropy (VCMA) effect appears more promising--it is successful for controlling the skyrmion motion--avoids the need for strong depinning currents, simplifies the fabrication process, and gives more freedom in the control logic. The anisotropy variation induced by the VCMA can create barriers or wells that can be used to limit the movement of domain walls and obtain an effective synchronization. In this article, we propose a system-level evaluation of the effectiveness of the proposed VCMA synchronization method. Starting from a two-coordinates model, the motion of domain walls, the performance, and the efficiency of the approach are evaluated. We modeled the delay using SPICE. The VCMA showed clear advantages in the realization of the confinement structure at the system level with respect to the notch solution

A Supervisory Control Strategy for Improving Energy Efficiency of Artificial Lighting Systems in Greenhouses

Artificial lighting systems are used in commercial greenhouses to ensure year-round yields. Current Light Emitting Diode (LED) technologies improved the system efficiency. Nevertheless, having artificial lighting systems extended for hectares with power densities over 50W/m2 causes energy and power demand of greenhouses to be really significant. The present paper introduces an innovative supervisory and predictive control strategy to optimize the energy performance of the artificial lights of greenhouses. The controller has been implemented in a multi-span plastic greenhouse located in North Italy. The proposed control strategy has been tested on a greenhouse of 1 hectare with a lighting system with a nominal power density of 50 Wm−2 requiring an overall power supply of 1 MW for a period of 80 days. The results have been compared with the data coming from another greenhouse of 1 hectare in the same conditions implementing a state-of-the-art strategy for artificial lighting control. Results outlines that potential 19.4% cost savings are achievable. Moreover, the algorithm can be used to transform the greenhouse in a viable source of energy flexibility for grid reliability

Skyrmion Logic-In-Memory Architecture for Maximum/Minimum Search

In modern computing systems there is the need to utilize a large amount of data in maintaining high efficiency. Limited memory bandwidth, coupled with the performance gap between memory and logic, impacts heavily on algorithms performance, increasing the overall time and energy required for computation. A possible approach to overcome such limitations is Logic-In-Memory (LIM). In this paper, we propose a LIM architecture based on a non-volatile skyrmion-based recetrack memory. The architecture can be used as a memory or can perform advanced logic functions on the stored data, for example searching for the maximum/minimum number. The circuit has been designed and validated using physical simulations for the memory array together with digital design tools for the control logic. The results highlight the small area of the proposed architecture and its good energy efficiency compared with a reference CMOS implementation

Genotype-phenotype correlation study in 364 osteogenesis imperfecta Italian patients

Osteogenesis imperfecta (OI) is a rare genetic disorder of the connective tissue and 90% of cases are due to dominant mutations in COL1A1 and COL1A2 genes. To increase OI disease knowledge and contribute to patient follow-up management, a homogeneous Italian cohort of 364 subjects affected by OI types I-IV was evaluated. The study population was composed of 262 OI type I, 24 type II, 39 type III, and 39 type IV patients. Three hundred and nine subjects had a type I collagen affecting function mutations (230 in α1(I) and 79 in α2(I)); no disease-causing changes were noticed in 55 patients. Compared with previous genotype-phenotype OI correlation studies, additional observations arose: a new effect for α1- and α2-serine substitutions has been pointed out and heart defects, never considered before, resulted associated to quantitative mutations (P = 0.043). Moreover, some different findings emerged if compared with previous literature; especially, focusing the attention on the lethal form, no association with specific collagen regions was found and most of variants localized in the previously reported "lethal clusters" were causative of OI types I-IV. Some discrepancies have been highlighted also considering the "50-55 nucleotides rule," as well as the relationship between specific collagen I mutated region and the presence of dentinogenesis imperfecta and/or blue sclera. Despite difficulties still present in defining clear rules to predict the clinical outcome in OI patients, this study provides new pieces for completing the puzzle, also thanks to the inclusion of clinical signs never considered before and to the large number of OI Italian patients

The natural history of multiple osteochondromas in a large Italian cohort of pediatric patients.

Abstract Importance Multiple osteochondromas is a rare hereditary skeletal disorder, characterized by bony protrusions arising from growth plates on long bones during skeletal development. The disorder frequently leads to diminished stature, deformities and functional limitations. Understanding of the natural history of multiple osteochondromas and its evolution in children and adolescents is limited. Objective To provide valuable information on the natural history of multiple osteochondromas, to inform recommendations for treatment and prevent impairments caused by osteochondromas. Design This retrospective cohort study in children with multiple osteochondromas includes longitudinal data collected from first to last follow-up visit for patient demographics, and over 36 months for disease evolution. Setting Data were collected from the Registry of Multiple Osteochondromas, which includes data from circa 1200 patients with multiple osteochondromas treated from 2003 to 2017 at IRCCS Istituto Ortopedico Rizzoli in Bologna. Participants Patients ≤18 years with multiple osteochondromas, who provided written informed consent and had data for ≥1 12-month follow-up visit. Main outcome(s) and measurement(s) Demographics, clinical features, incidence of surgeries, and disease evolution (progression or regression) were assessed. Results were summarized using descriptive statistics, annual rates of new clinical features and surgeries, and Kaplan-Meier estimates. Patient height was evaluated following Italian growth charts. Results 158 patients were included in these analyses. Throughout follow-up, 80.4% of patients developed new osteochondromas, 57.6% developed new deformities, 23.4% developed new functional limitation(s). New osteochondroma(s) were developed by 28.5% patients by Month 12, 39.9% at Month 24, 50% at Month 36. Most new osteochondromas were detected in the younger population; patients aged 0–4 years underwent a significantly higher number of lesions within 12, 24 and 36 months of follow-up. The overall incidence of patients with ≥1 new deformity within 12 months was 17.7%, with incidences decreasing with increasing age (p = .023). In addition, the analyses on height highlight that 13 years is a cut off age for slow growth of the stature (p  Conclusions and relevance This natural history study reports the main set of clinically relevant data for patients with multiple osteochondromas during skeletal development, providing insight for patient management and development of therapeutic interventions

Enabling Logic Computation Between Ta/CoFeB/MgO Nanomagnets

Dipolar coupled magnets proved to have the potential to be capable of successfully performing digital computation in a highly parallel way. For that, nanomagnet-based computation requires precise control of the domain wall nucleation from a well-localized region of the magnet. Co/Pt and Co/Ni multilayer stacks were successfully used to demonstrate a variety of computing devices. However, Ta/CoFeB/MgO appears more promising, thanks to the lower switching field required to achieve a full magnetization reversal, reduced thickness (less than 10 nm), and its compatibility with magnetic tunnel junctions. In this work, the switch of the information is achieved through the application of a magnetic field, which allows to scale more the nanomagnets with respect to current-driven magnetization reversal-based devices and to go toward 3-D structures. We experimentally demonstrate that Ga ions can be used to tune the energy landscape of the structured magnets to provide signal directionality and achieve a distinct logic computation. We prove that it is possible to define the artificial nucleation center (ANC) in different structures with two irradiation steps and that this approach can enable logic computation in ultrathin films by dipolar interaction. Moreover, different from previous studies, the results coming from the irradiation analysis are then used for real logic devices. We present the experimental demonstration of a set of fully working planar inverters, showing that it is possible to reach a coupling field between the input and the output, which is strong enough to reliably implement logic operations. Micromagnetic simulations are used to study the nucleation center's effectiveness with respect to its position in the magnet and to support the experiments. Our results open the path to the development of more efficient nanomagnet-based logic circuits

Variable clinical expression of Stickler Syndrome: A case report of a novel COL11A1 mutation

n/

COL1-Related Disorders: Case Report and Review of Overlapping Syndromes

Collagen type I mutations are related to wide phenotypic expressions frequently causing an overlap of clinical manifestations, in particular between Osteogenesis Imperfecta (OI) and Ehlers-Danlos syndrome (EDS). Both disorders present inter- and intra-familial clinical variability and several clinical signs are present in both diseases. Recently, after the observation that some individuals first ascertained by a suspicion of EDS resulted then carriers of pathogenic variants of genes known to primarily cause OI, some authors proposed the term “COL1-related overlap disorder” to describe these cases. In this paper, we report clinical, molecular, and biochemical information about an individual with a diagnosis of EDS with severe joint hypermobility who carries a pathogenic heterozygous variant in COL1A2 gene, and a benign variant in COL1A1 gene. The pathogenic variant, commonly ascribed to OI, as well as the benign variant, has been inherited from the individual's mother, who presented only mild signs of OI and the diagnosis of OI was confirmed only after molecular testing. In addition, we reviewed the literature of similar cases of overlapping syndromes caused by COL1 gene mutations. The reported case and the literature review suggest that the COL1-related overlap disorders (OI, EDS and overlapping syndromes) represent a continuum of clinical phenotypes related to collagen type I mutations. The spectrum of COL1-related clinical manifestations, the pathophysiology and the underlying molecular mechanisms support the adoption of the updated proposed term “COL1-related overlap disorder” to describe the overlapping syndromes

Controlling Domain-Wall Nucleation in Ta/CoFeB/MgO Nanomagnets via Local Ga+ Ion Irradiation

Comprehensive control of the domain wall nucleation process is crucial for spin-based emerging technologies ranging from random-access and storage-class memories over domain-wall logic concepts to nanomagnetic logic. In this work, focused Ga+ ion-irradiation is investigated as an effective means to control domain-wall nucleation in Ta/CoFeB/MgO nanostructures. We show that analogously to He+ irradiation, it is not only possible to reduce the perpendicular magnetic anisotropy but also to increase it significantly, enabling new, bidirectional manipulation schemes. First, the irradiation effects are assessed on film level, sketching an overview of the dose-dependent changes in the magnetic energy landscape. Subsequent time-domain nucleation characteristics of irradiated nanostructures reveal substantial increases in the anisotropy fields but surprisingly small effects on the measured energy barriers, indicating shrinking nucleation volumes. Spatial control of the domain wall nucleation point is achieved by employing focused irradiation of pre-irradiated magnets, with the diameter of the introduced circular defect controlling the coercivity. Special attention is given to the nucleation mechanisms, changing from a Stoner-Wohlfarth particle's coherent rotation to depinning from an anisotropy gradient. Dynamic micromagnetic simulations and related measurements are used in addition to model and analyze this depinning-dominated magnetization reversal