Mixed-Dimensional Formamidinium Bismuth Iodides Featuring In-Situ Formed Type-I Band Structure for Convolution Neural Networks.

For valence change memory (VCM)-type synapses, a large number of vacancies help to achieve very linearly changed dynamic range, and also, the low activation energy of vacancies enables low-voltage operation. However, a large number of vacancies increases the current of artificial synapses by acting like dopants, which aggravates low-energy operation and device scalability. Here, mixed-dimensional formamidinium bismuth iodides featuring in-situ formed type-I band structure are reported for the VCM-type synapse. As compared to the pure 2D and 0D phases, the mixed phase increases defect density, which induces a better dynamic range and higher linearity. In addition, the mixed phase decreases conductivity for non-paths despite a large number of defects providing lots of conducting paths. Thus, the mixed phase-based memristor devices exhibit excellent potentiation/depression characteristics with asymmetricity of 3.15, 500 conductance states, a dynamic range of 15, pico ampere-scale current level, and energy consumption per spike of 61.08 aJ. A convolutional neural network (CNN) simulation with the Canadian Institute for Advanced Research-10 (CIFAR-10) dataset is also performed, confirming a maximum recognition rate of approximately 87%. This study is expected to lay the groundwork for future research on organic bismuth halide-based memristor synapses usable for a neuromorphic computing system.

Asymmetric carrier transport in flexible interface-type memristor enables artificial synapses with sub-femtojoule energy consumption.

Flexible and transparent artificial synapses with extremely low energy consumption have potential for use in brain-like neuromorphic electronics. However, most of the transparent materials for flexible memristive artificial synapses were reported to show picojoule-scale high energy consumption with kiloohm-scale low resistance, which limits the scalability for parallel operation. Here, we report on a flexible memristive artificial synapse based on Cs3Cu2I5 with energy consumption as low as 10.48 aJ (= 10.48 × 10-18 J) µm-2 and resistance as high as 243 MΩ for writing pulses. Interface-type resistive switching at the Schottky junction between p-type Cu3Cs2I5 and Au is verified, where migration of iodide vacancies and asymmetric carrier transport owing to the effective hole mass is three times heavier than effective electron mass are found to play critical roles in controlling the conductance, leading to high resistance. There was little difference in synaptic weight updates with high linearity and 250 states before and after bending the flexible device. Moreover, the MNIST-based recognition rate of over 90% is maintained upon bending, indicative of a promising candidate for highly efficient flexible artificial synapses.

Solitary lymphoblastic lymphoma of the thoracic spine.

Non-Hodgkin's lymphoma rarely originates from bone, and even more infrequently from a vertebral body. Lymphoblastic lymphoma is a rare type of non-Hodgkin's lymphoma, and results from an abnormality in adaptive immune cells. A 27-year-old man presented with a two-month history of night sweats, weight loss, and severe back pain. Radiological studies demonstrated an osteolytic lesion compressing the subarachnoid space at the T11 level. Posterolateral fusion with decompression was performed and a pathologic examination confirmed lymphoblastic lymphoma of the B-cell precursor type. To our knowledge, this is the first report of solitary lymphoblastic lymphoma from B-cell precursors in of the thoracic spine. Herein, we discuss the presenting symptoms and the management of this rare case of lymphoblastic lymphoma.

Paraspinal Muscle Sparing Versus Percutaneous Screw Fixation: A Comparative Enzyme Study of Tissue Injury during the Treatment of L4-L5 Spondylolisthesis.

OBJECTIVE: Screw fixation via the paraspinal muscle sparing approach and by percutaneous screw fixation are known to diminish the risk of complications, such as, iatrogenic muscle injury as compared with the conventional midline approach. The purpose of this study was to evaluate tissue injury markers after these less traumatic screw fixation techniques for the treatment of L4-L5 spondylolisthesis. METHODS: Twenty-two patients scheduled for posterior lumbar interbody fusion (PLIF) at the L4-L5 segment for spondylolisthesis were prospectively studied. Patients were divided into two groups by screw fixation technique (Group I: paraspinal muscle sparing approach and Group II: percutaneous screw fixation). Levels of serum enzymes representing muscle injury (CK-MM and Troponin C type 2 fast), pro-inflammatory cytokine (IL-8), and anti-inflammatory cytokine (IL-1ra) were analyzed using ELISA techniques on the day of the surgery and 1, 3, and 7 days after the surgery. RESULTS: Serum CK-MM, Troponic C type 2 fast (TNNC2), and IL-1ra levels were significantly elevated in Group I on postoperative day 1 and 3, and returned to preoperative levels on postoperative day 7. No significant intergroup difference was found between IL-8 levels despite higher concentrations in Group I on postoperative day 1 and 3. CONCLUSION: This study shows that percutaneous screw fixation procedure is the preferable minimally invasive technique in terms of minimizing muscle injury associated with L4-L5 spondylolisthesis.

Symptomatic myelopathy caused by ossification of the yellow ligament.

OBJECTIVE: This study was performed to describe the clinical presentation, surgical outcome in patients with symptomatic myelopathy caused by ossification of the yellow ligament (OYL). METHODS: The authors reviewed consequent 12 patients in whom posterior decompressive laminectomies were performed for OYL from 1999 to 2005. Diagnostic imagings including simple radiographs, computed tomography and magnetic resonance images were performed in each case. The patients were reviewed to evaluate the clinical presentation, surgical outcome and complications of the operation. RESULTS: In all patients, OYL was located in the lower thoracic region and all patients presented with numbness on both limbs and pain. Among them, 5 patients presented with gait disturbance due to paraparesis and two patients had sphincter dysfunction. Decompressive laminectomy through a posterior approach using microscope resulted in improvement of symptoms in all patients, but, recovery was incomplete in a half of the patients. The mean postoperative Japanese orthopaedics association (JOA) score was 7.9 when compared with 4.9 in preoperative assessment and the mean recovery rate was 65%. Dural tear was noticed in four patients, so dural repair was performed, but there were no neurological deficits related to neural injury. CONCLUSION: OYL is an uncommon cause of myelopathy but it can lead to debilitating thoracic myelopathy. Careful decompressive laminectomy can achieve favorable results.