Optic Memory Research Articles

Magnetically tunable ultralow threshold optical bistability by exciting LRSPR in InAs/graphene layers at the terahertz region.

With the experimental corroboration employing a transfer matrix method, an analytical observation of optical bistability using long-range surface plasmon resonance (LRSPR) through the external magnetic field is presented for a very low threshold value. The proposed analytical method has been verified with the reported experimental data provided by Liu etal. [Curr. Appl. Phys.29, 66 (2021)1567-173910.1016/j.cap.2021.06.003]. Now theoretical analysis is further extended in the proposed multilayered structure comprising an InAs layer sandwiched between two graphene layers, whose electromagnetic response at 2THz can be regulated by employing a magnetic field and may tune the optical bistability without modifying the geometry or the characteristics of the structure. The observed threshold intensity for the switch-up is 6.6615×104 W/c m 2 at 0.001T; thus, this analytical approach is able to achieve 2 orders lower threshold for magnetically tunable upswitching of the optical bistable process. This suggested magnetically adjustable optical bistable arrangement gives a possibility for the comprehension of optical logic gates, optic memory, opto-transistors, and switches at a low switching threshold due to extraordinary features of the composite layers due to local field amplification of the graphene layer.

Endonasal endoscopic resection of suprasellar craniopharyngioma: A retrospective single-center case series

IntroductionEndoscopic endonasal approach (EEA) has recently been proposed as an option for resection of primary and recurrent suprasellar craniopharyngioma. However, surgical outcome has not yet been fully evaluated, especially in regards to recurrent cases. MethodsWe analysed our institution (Sir Charles Gairdner University Hospital, Perth, Australia) case-series retrospectively. There were 16 patients operated through an endonasal endoscopic approach from February 2014 to February 2019 for suprasellar craniopharyngiomas. There were 14 primary, and two recurrent lesions. Extent of resection, complications, visual and endocrinological outcomes are presented. ResultsMean age of the patients was 42.9 ± 19.3 years old, with 56% female. The most common clinical symptoms were headaches (9 patients, 56%) and bi-temporal hemianopsia (9 patients, 56%), followed by unilateral optic neuropathy (5 cases, 31%), memory loss (1 case, 6%), hydrocephalus (1 case, 6%), delayed growth and puberty (1 case, 6%), and secondary amenorrhoea (1 case, 6%). Only two cases (12%) initially presented with normal visual function. Gross total resection (GTR) was achieved in 10/16 patients (62.5%), with subtotal resection (STR) in the remainder. Visual symptoms improved in 13/16 patients (81%) and remained unchanged in 3/16 patients (19%). Most common complications included new endocrinological deficit in nine patients (56%), mostly diabetes insipidus, and cerebrospinal fluid leak requiring a new intervention in three patients (19%). There was one mortality case (complicated meningitis, stroke and vasospasm). Mean follow-up time was 22.05 ± 14 months and three patients (19%) had a recurrence of the disease during this period and were referred for radiation therapy. ConclusionEndonasal endoscopic approach is a safe and effective surgical option for both primary and recurrent suprasellar craniopharyngiomas.

High figure of merit magneto-optics from interfacial skyrmions on topological insulators

In the Kerr rotation geometry, magneto-optic memory devices typically suffer from low figure-of-merit (FOM) and long write times. We show that skyrmions formed at the interface of a thin-film multiferroic and a topological insulator can give rise to high FOM magneto-optic Kerr effects (MOKEs). Huge differential MOKE can arise in parts of the phase diagram. Resonancelike features in the MOKE spectra arising from the induced low energy TI band gap, the multiferroic-film thickness, and the high energy Drude-like behavior are resolved and explained. The Fermi level dependence of the MOKE signatures is distinct for the different magnetic textures. This has broad implications for magnetic texture characterization, electro-optic modulators and isolators, and high density magnetic optic memory.

Improved Electro-Optical Response of Induced Chiral Nematic Liquid Crystal Doped with Multi-Walled Carbon Nanotubes

ABSTRACTMultiwalled carbon nanotubes functionalized with COOH were dispersed into induced chiral nematic liquid crystals confined in a planar aligned cell. Dopant concentration was varied to investigate electro-optical behaviour and morphology of the doped samples in the presence of surface anchoring forces. An increase in the conductivity, refractive index, and dielectric constant of the material was observed. Polarized fluorescence spectroscopy confirmed the anisotropic changes brought in by CNT doping. A significant change in the onset voltage of Freedericksz transition and an emergence of electro optic memory due to stabilization of the sample by nanotubes ensure the practical use of the material.

Photonic XOR with inherent loss compensation mechanism for memory cell implementation in a standard nanoscale very large-scale integrated fabrication process

A multilayer photonic XOR gate is presented. The XOR is implemented by the interconnect layers of a microelectronic chip and is suitable for fabrication in a standard VLSI fabrication process. The proposed device features an inherent insertion loss compensation mechanism by utilization of nanometric holes, making it possible to implement an optic memory cell without the need of additional complex compensation devices. The structure of such a memory cell, implemented by utilization of two proposed XOR gates, configured to perform the NOT function, is shown. The unique structure of the proposed device allows us to significantly reduce sensitivity to process variations and therefore makes it possible to utilize the memory cell in state-of-the-art nanoscale processes. The proposed memory can be integrated with conventional electronics on the same VLSI chip.

A 63-year-old woman with urinary incontinence and progressive gait disorder

A patient reported fatigue and imbalance for “most of her life.” As a child, she walked more slowly than others and had difficulty ice skating. She noted definite gait impairment about 16 years before presentation and this was more noticeable to her family 13 years before presentation. Since then, she had a slowly progressive gait disorder. She started using a cane 4 years before presentation, a walker 2 years before presentation, and a scooter about 1 year ago. She developed bladder frequency and urge incontinence about 15 years before presentation, which also slowly worsened. She reported some pain and “dead feeling” in her feet that worsened in the evening and when tired. She had never experienced attack-like worsening or resolution of her neurologic symptoms, and had no history of optic neuritis, brainstem symptoms, or memory impairment. CSF examination 13 years previously was reportedly negative for multiple sclerosis (MS) and tests for adrenomyeloneuropathy and genetic testing for inherited spastic paraparesis were reportedly negative. Interferon β-1a IM once weekly was started 10 years previously but was discontinued after 1 year for lack of benefit and switched to glatiramer acetate, which the patient remained on for 7 months. She was then treated with mitoxantrone, which was discontinued because of echocardiogram abnormalities, which improved after its discontinuation. Over the previous 1 year, she was receiving monthly IV immunoglobulin G (IVIg) and had received scheduled IV corticosteroids monthly with mild transient symptomatic improvement lasting only 6 months. She had dry mouth, which was attributed to medication, and occasional mild headaches, but no significant constitutional symptoms or significant travel history. She had a history of tick exposure but had negative Lyme disease testing. She had had a hysterectomy for benign tumor with deep venous thrombosis following surgery, prior sinus and lumbar surgery, and hyperlipidemia. Her medications …

1310 FBG センサと SMA 繊維を用いた組物 GFRP の損傷検知および制御

Damage detection and control of braided grass fiber reinforced plastics (GFRP) were conducted by using embedded Fiber Bragg Grating (FBG) fiber optic sensors and Shape Memory Alloy (SMA) wire actuators during tensile and fatigue tests. The sensors and actuators were embedded warpwise in braided composites. Reflected optical spectrum from FBG sensors were used for evaluation of damages during by calculating the maximum correlation coefficient with the initial spectrum. The experimental results showed that the sensors could detect damage initiation and actuators could suppress development of the damages.

Polymer Dispersed Liquid Crystal Thin Films for Optical Processing

Abstract A shape-controlled bistable hysteresis is observed for thin polymer dispersed liquid crystal films when inserted in feedback systems where the applied voltage depends on the intensity of the light transmitted by the film. A control of the hysteresis width is possible by acting on the parameters of the feedback circuit The possibility of obtaining bistable regions of different width can be very useful in view of the application of PDLC as optic memory elements or binary data transmission devices. An investigation on the use of these films as optical switches for fiber interconnects is also performed and the preliminary results are reported. Technical improvements are suggested in order to increase the on/off contrast ratio of the switching behavior.

Cloning and sequencing the genes encoding goldfish and carp ependymin.

Ependymins (EPNs) are brain glycoproteins thought to function in optic nerve regeneration and long-term memory consolidation. To date, epn genes have been characterized in two orders of teleost fish. In this study, polymerase chain reactions (PCR) were used to amplify the complete 1.6-kb epn genes, gf-I and cc-I, from genomic DNA of Cypriniformes, goldfish and carp, respectively. Amplified bands were cloned and sequenced. Each gene consists of six exons and five introns. The exon portion of gf-I encodes a predicted 215-amino-acid (aa) protein previously characterized as GF-I, while cc-I encodes a predicted 215-aa protein 95% homologous to GF-I.

Fiber optic delay line memory

A model for digital synchronous delay line memory (DSDLM) is given, yielding limitations on the maximum number of bits that can be reliably stored for a given change in delay medium temperature and amount of medium dispersion. More than 22 million bits can be stored when single-mode optical fiber is used as the medium, but only if operated at the wavelength of minimum dispersion and by limiting thermal fluctuations to within 0.002 degrees C. A DSDLM is being constructed using such fiber, along with lithium niobate directional couplers as the switching elements. Signal regeneration errors, switch crosstalk, and polarization losses are negligible for the implementation. With a modulation frequency of 100 MHz, a single-line 2000-bit memory can be reliably operated without thermal compensation given a temperature fluctuation of <80 degrees C.

Optic flow, icons, and memory

Optic flow, icons, and memory