Spintronic virtual neural network by a voltage controlled ferromagnet for associative memory.

Recently, an associative memory operation by a virtual oscillator network, consisting of a single spintronic oscillator, was examined to solve issues in conventional, real oscillators-based neural networks such as inhomogeneities between the oscillators. However, the spintronic oscillator still carries issues dissipating large amount of energy because it is driven by electric current. Here, we propose to use a single ferromagnet manipulated by voltage-controlled magnetic anisotropy (VCMA) effect as a fundamental element in a virtual neural network, which will contribute to significantly reducing the Joule heating caused by electric current. Instead of the oscillation in oscillator networks, magnetization relaxation dynamics were used for the associative memory operation. The associative memory operation for alphabet patterns is successfully demonstrated by giving correspondences between the colors in a pattern recognition task and the sign of a perpendicular magnetic anisotropy coefficient, which could be either positive or negative via the VCMA effect.

Bifurcation to complex dynamics in largely modulated voltage-controlled parametric oscillator.

An experimental demonstration of a parametric oscillation of a magnetization in a ferromagnet was performed recently by applying a microwave voltage, indicating the potential to be applied in a switching method in non-volatile memories. In the previous works, the modulation of a perpendicular magnetic anisotropy field produced by the microwave voltage was small compared with an external magnetic field pointing in an in-plane direction. A recent trend is, however, opposite, where an efficiency of the voltage controlled magnetic anisotropy (VCMA) effect is increased significantly by material research and thus, the modulated magnetic anisotropy field can be larger than the external magnetic field. Here, we solved the Landau-Lifshitz-Gilbert equation numerically and investigated the magnetization dynamics driven under a wide range of the microwave VCMA effect. We evaluated bifurcation diagrams, which summarize local maxima of the magnetization dynamics. For low modulation amplitudes, the local maximum is a single point because the dynamics is the periodic parametric oscillation. The bifurcation diagrams show distributions of the local maxima when the microwave magnetic anisotropy field becomes larger than the external magnetic field. The appearance of this broadened distribution indicates complex dynamics such as chaotic and transient-chaotic behaviors, which were confirmed from an analysis of temporal dynamics.

Unilateral tonsillitis due to primary syphilis with gram-negative corkscrew-like spirochaetes confirmed by Gram stain of pus.

A man in his 40s presented with pharyngeal pain and right cervical lymphadenopathy that persisted for 1 month. His right tonsil was swollen and covered with exudate; however, a rapid streptococcal antigen test was negative. Rapid plasma reagin and Treponema pallidum antibody were positive. Gram staining of the pus confirmed the presence of gram-negative corkscrew-like spirochaetes. The patient had unprotected oral intercourse. He did not have any skin lesions. He was diagnosed with primary syphilis and treated with benzathine penicillin G. In adults, the differential diagnosis of tonsillitis should include sexually transmitted diseases. A rapid streptococcal antigen test is not sufficient for such a case; a syphilis test is necessary, and Gram staining, which is rapid and does not need any special equipment, can support the diagnosis.

Associative memory by virtual oscillator network based on single spin-torque oscillator.

A coupled oscillator network may be able to perform an energy-efficient associative memory operation. However, its realization has been difficult because inhomogeneities unavoidably arise among the oscillators during fabrication and lead to an unreliable operation. This issue could be resolved if the oscillator network were able to be formed from a single oscillator. Here, we performed numerical simulations and theoretical analyses on an associative memory operation that uses a virtual oscillator network based on a spin-torque oscillator. The virtual network combines the concept of coupled oscillators with that of feedforward neural networks. Numerical experiments demonstrate successful associations of 60-pixel patterns with various memorized patterns. Moreover, the origin of the associative memory is shown to be forced synchronization driven by feedforward input, where phase differences among oscillators are fixed and correspond to the colors of the pixels in the pattern.

Septic shock due to Pseudomonas fulva potentially caused by percutaneous infection: A case report.

Pseudomonas fulva is a Gram-negative rod that was isolated from Japanese paddy rice, and few cases of infections due to trauma, catheters, or contaminated infusion products have been reported. We report a case of P. fulva infection in an older patient who developed septic shock due to P. fulva during hospitalization after treatment for aspiration pneumonia. Since signs of infection were seen at the skin epidermal exfoliation site, which had been present since admission, this was considered to be the route of infection. The patient recovered on treatment with piperacillin. It was suggested that P. fulva can infect minor wounds in older individuals and lead to sepsis, even if the infection is not caused by a medical device or from severe trauma from an accident. This means that even small wounds, especially in older individuals, should be treated with caution, and a full body examination, including the skin, is essential even at the onset of sepsis. Although P. fulva has been identified as P. putida in many cases by conventional bacterial identification tests, it is expected that more cases will be accurately identified with the widespread use of polymerase chain reaction and mass spectrometry.

Structural basis of spike RBM-specific human antibodies counteracting broad SARS-CoV-2 variants.

The decrease of antibody efficacy to mutated SARS-CoV-2 spike RBD explains the breakthrough infections and reinfections by Omicron variants. Here, we analyzed broadly neutralizing antibodies isolated from long-term hospitalized convalescent patients of early SARS-CoV-2 strains. One of the antibodies named NCV2SG48 is highly potent to broad SARS-CoV-2 variants including Omicron BA.1, BA.2, and BA.4/5. To reveal the mode of action, we determined the sequence and crystal structure of the Fab fragment of NCV2SG48 in a complex with spike RBD from the original, Delta, and Omicron BA.1. NCV2SG48 is from a minor VH but the multiple somatic hypermutations contribute to a markedly extended binding interface and hydrogen bonds to interact with conserved residues at the core receptor-binding motif of RBD, which efficiently neutralizes a broad spectrum of variants. Thus, eliciting the RBD-specific B cells to the longitudinal germinal center reaction confers potent immunity to broad SARS-CoV-2 variants emerging one after another.

Input-driven chaotic dynamics in vortex spin-torque oscillator.

A new research topic in spintronics relating to the operation principles of brain-inspired computing is input-driven magnetization dynamics in nanomagnet. In this paper, the magnetization dynamics in a vortex spin-torque oscillator driven by a series of random magnetic field are studied through a numerical simulation of the Thiele equation. It is found that input-driven synchronization occurs in the weak perturbation limit, as found recently. As well, chaotic behavior is newly found to occur in the vortex core dynamics for a wide range of parameters, where synchronized behavior is disrupted by an intermittency. Ordered and chaotic dynamical phases are examined by evaluating the Lyapunov exponent. The relation between the dynamical phase and the computational capability of physical reservoir computing is also studied.

High Yield of Blood Cultures in the Etiologic Diagnosis of Cellulitis, Erysipelas, and Cutaneous Abscess in Elderly Patients.

Background: Cellulitis is a common disease in the elderly, and detecting etiologic organisms with blood cultures is difficult because of the low positive rate and occasional skin contamination. Therefore, routine blood cultures are not recommended for uncomplicated cellulitis. However, it is unclear whether blood culture collection for the diagnosis of cellulitis in elderly patients is useful. Methods: This single hospital-based observational study was performed between April 2012 and March 2015 in Okinawa, Japan. All enrolled patients were aged 15 years or older and admitted to the Division of Infectious Diseases with suspected cellulitis, erysipelas, and cutaneous abscess. Two routine sets of blood cultures were obtained. Results: Two hundred and twenty-one patients were enrolled. The median age was 77 years. The proportion of bacteremia was 21.7% for all patients (48/221), 8.5% (4/47) for those <65 years, and 25.3% (44/174) for those ≥65 years old (P = .013). The skin contamination rate was 0.9% (2/221). The most common pathogen was Streptococcus dysgalactiae (62.5%). Gram-negative bacteremia not susceptible to cefazolin was detected in 8.3%. Cefazolin and ampicillin were the first- and second-most commonly used therapies. Anti-methicillin-resistant Staphylococcus aureus therapy was required in 3.6% of patients. In addition to age and severe infection, shaking chills and white blood count ≥13 000 cells/µL were independent risk factors of bacteremia. Conclusions: Two routine sets of blood cultures are recommended for the precise diagnosis and appropriate treatment of cellulitis in elderly patients, especially in patients with shaking chills or leukocytosis.

Ultra-wide-band millimeter-wave generator using spin torque oscillator with strong interlayer exchange couplings.

Recent increased development interest in millimeter-wave oscillator devices has necessitated realization of small oscillators with high frequency, wide frequency tunability, and room-temperature operation. Spin-torque oscillators (STOs) are fascinating candidates for such applications because of their nanometer size and suitability for room-temperature operation. However, their oscillation frequency and tunable range are limited to the order of 100 MHz-10 GHz. Here, we propose use of bilinear (J1) and biquadratic (J2) interlayer exchange couplings between ferromagnets in STOs to overcome these problems. The bilinear coupling contributes to oscillation frequency enhancement, whereas the biquadratic coupling facilitates frequency tunability via a current. Using micromagnetic simulation with parameters estimated from a material with small saturation magnetization, for J1 = 0 and J2 = - 1.0 mJ/m2, respectively, we find that the STO exhibits high frequency from 23 to 576 GHz and that its tunability reaches 61 GHz/(1011 A/m2) for current densities of - 0.5 to - 9.5 × 1011 A/m2. An analytical theory based on the macrospin model is also developed, which exhibits good quantitative agreement with the micromagnetic simulations. These results introduce new possibilities for spintronics applications in high-frequency devices such as next-generation mobile communications.

Spintronic reservoir computing without driving current or magnetic field.

Recent studies have shown that nonlinear magnetization dynamics excited in nanostructured ferromagnets are applicable to brain-inspired computing such as physical reservoir computing. The previous works have utilized the magnetization dynamics driven by electric current and/or magnetic field. This work proposes a method to apply the magnetization dynamics driven by voltage control of magnetic anisotropy to physical reservoir computing, which will be preferable from the viewpoint of low-power consumption. The computational capabilities of benchmark tasks in single MTJ are evaluated by numerical simulation of the magnetization dynamics and found to be comparable to those of echo-state networks with more than 10 nodes.

Point-of-care urine Gram stain led to narrower-spectrum antimicrobial selection for febrile urinary tract infection in adolescents and adults.

BACKGROUND: Febrile urinary tract infections (fUTIs), which include pyelonephritis, prostatitis, and urosepsis, are the most common cause of sepsis. However, the treatment has become more complex because of the worldwide increase in antimicrobial resistance (AMR). The objective of this study was to clarify whether point-of-care Gram stain (PCGS) of urine contributed to fUTI diagnosis and treatment in adults. METHODS: This hospital-based observational study was undertaken between January 2013 and March 2015 in Okinawa, Japan. All enrolled patients were adults who had been admitted to the Division of Infectious Diseases with suspected fUTI. The usefulness of PCGS results were compared for urinalysis (U/A) and urine cultures (U/Cs). The targeted therapy type and its susceptibility based on PCGS were analyzed, and each was investigated in two groups: the uncomplicated pyelonephritis group and the complicated pyelonephritis/prostatitis group. RESULTS: Two hundred and sixty-six patients were enrolled. The results of PCGS were closely correlated with those of U/A for pyuria and bacteriuria, and moderately correlated with the results of U/C for bacterial types. In the uncomplicated group, narrow-spectrum antimicrobials such as cefotiam were initially selected in 97.9% (47/48) of patients, and their susceptibility was 97.9% (47/48). In the complicated group, the susceptibility was 84.2% (186/221) (p = 0.009) despite frequent AMRs (14.7%; 32/218) and low use of broad-spectrum antimicrobials such as carbapenems (7.7%; 17/221). CONCLUSION: Urine PCGS led to a more precise fUTI diagnosis and prompted clinicians to select narrower-spectrum antibiotics with high susceptibility.

Effect of baricitinib in patients with coronavirus disease 2019 and respiratory failure: A propensity score-matched retrospective cohort study.

In this retrospective cohort study, we evaluated the efficacy of baricitinib in the treatment of coronavirus disease 2019 (COVID-19). Among 404 adult patients with COVID-19 who were admitted to our hospital between October 23, 2020, and July 31, 2021, 229 patients with respiratory failure were included. Among these, 41 patients in the baricitinib group and 41 patients in the control group were selected by propensity score matching to adjust for background factors. We compared the survival rates of the two groups at 30 and 60 days after admission. The 30-day survival rate was significantly higher in the baricitinib group than in the control group. However, there was no significant difference in 60-day survival in the two groups. Baricitinib may improve the early prognosis of patients with respiratory failure associated with COVID-19. However, efforts should be made to improve the long-term prognosis.

Giant charge-to-spin conversion in ferromagnet via spin-orbit coupling.

Converting charge current into spin current via the spin Hall effect enables efficient manipulation of magnetization by electrical current. However, its geometrical restriction is a serious obstacle to device applications because it prevents switching of perpendicular magnetization in the absence of an external field. To resolve this issue, ferromagnetic materials have attracted attentions because their time reversal asymmetry induces magnetic-dependent charge-to-spin conversion that removes this restriction. Here, we achieved a large enhancement of magnetic-dependent charge-to-spin conversion by clarifying its mechanism. Through layer thickness dependence of the conversion efficiency, we revealed a coexistence of interfacial and bulk contributions to the magnetic-dependent charge-to-spin conversion. Moreover, the interfacial contribution to charge-to-spin conversion is found to be dominant and can be controlled via interfacial band engineering. The efficiency of charge-to-spin conversion in ferromagnet was found to be an order larger than that of other materials with reduced symmetry.

Varicella caused by airborne transmission of a localised herpes zoster infection in a family.

Localised herpes zoster infections spread by direct contact with active skin lesion, but airborne transmission is rare. We report a case of varicella from airborne transmission of a localised herpes zoster infection in a family. The patient was a 15-year-old boy who had never been vaccinated against the varicella-zoster virus (VZV). He likely developed varicella from his father, whom the patient lived with. The patient's father developed a localised herpes zoster infection 2 weeks prior. The patient's varicella was hypothesised to be due to VZV spread via airborne transmission from the father's localised infection. To decrease the number of varicella cases, routine vaccination of children against VZV is essential, and immunisation against VZV in middle-aged and elderly patients is also necessary.

Control of the stochastic response of magnetization dynamics in spin-torque oscillator through radio-frequency magnetic fields.

Neuromorphic computing using spintronic devices, such as spin-torque oscillators (STOs), has been intensively studied for energy-efficient data processing. One of the critical issues in this application is stochasticity in magnetization dynamics, which limits the accuracy of computation. Such stochastic behavior, however, plays a key role in stochastic computing and machine learning. It is therefore important to develop methods for both suppressing and enhancing stochastic response in spintronic devices. We report on experimental investigations on control of stochastic quantity, such as the width of a distribution of transient time in magnetization dynamics in vortex-type STO. The spin-transfer effect can suppress stochasticity in transient dynamics from a non-oscillating to oscillating state, whereas an application of a radio-frequency magnetic field is effective in reducing stochasticity on the time evolution of the oscillating state.

Spin-orbit torque driven magnetization switching in W/CoFeB/MgO-based type-Y three terminal magnetic tunnel junctions.

We have studied current induced magnetization switching in W/CoFeB/MgO based three terminal magnetic tunnel junctions. The switching driven by spin-orbit torque (SOT) is evaluated in the so-called type-Y structure, in which the magnetic easy-axis of the CoFeB layer lies in the film plane and is orthogonal to the current flow. The effective spin Hall angle estimated from the bias field dependence of critical current (Ic) is ~ 0.07. The field and current dependence of the switching probability are studied. The field and DC current induced switching can be described using a model based on thermally assisted magnetization switching. In contrast, the 50 ns long pulse current dependence of the switching probability shows significant deviation from the model, even if contribution from the field-like torque is included. The deviation is particularly evident when the threshold switching current is larger. These results show that conventional thermally assisted magnetization switching model cannot be used to describe SOT induced switching using short current pulses.

A multicenter non-randomized, uncontrolled single arm trial for evaluation of the efficacy and the safety of the treatment with favipiravir for patients with severe fever with thrombocytopenia syndrome.

Severe fever with thrombocytopenia syndrome (SFTS) is a bunyavirus infection with high mortality. Favipiravir has shown effectiveness in preventing and treating SFTS virus (SFTSV) infection in animal models. A multicenter non-randomized, uncontrolled single arm trial was conducted to collect data on the safety and the effectiveness of favipiravir in treatment of SFTS patients. All participants received favipiravir orally (first-day loading dose of 1800 mg twice a day followed by 800 mg twice a day for 7-14 days in total). SFTSV RT-PCR and biochemistry tests were performed at designated time points. Outcomes were 28-day mortality, clinical improvement, viral load evolution, and adverse events (AEs). Twenty-six patients were enrolled, of whom 23 were analyzed. Four of these 23 patients died of multi-organ failure within one week (28-day mortality rate: 17.3%). Oral favipiravir was well tolerated in the surviving patients. AEs (abnormal hepatic function and insomnia) occurred in about 20% of the patients. Clinical symptoms improved in all patients who survived from a median of day 2 to day10. SFTSV RNA levels in the patients who died were significantly higher than those in the survivors (p = 0.0029). No viral genomes were detectable in the surviving patients a median of 8 days after favipiravir administration. The 28-day mortality rate in this study was lower than those of the previous studies in Japan. The high frequency of hepatic dysfunction as an AE was observed. However, it was unclear whether this was merely a side effect of favipiravir, because liver disorders are commonly seen in SFTS patients. The results of this trial support the effectiveness of favipiravir for patients with SFTS.

Point-of-care cerebrospinal fluid Gram stain for the management of acute meningitis in adults: a retrospective observational study.

BACKGROUND: Gram stain of cerebrospinal fluid (CSF) is widely used in the diagnosis of acute meningitis, however, it is often conducted in the laboratory, as only some hospitals have access to point-of-care Gram stain (PCGS). The purpose of this study was to demonstrate the clinical impact and utility of PCGS in diagnosing and treating both bacterial and aseptic meningitis in adults. METHODS: This was a hospital-based, retrospective observational study at a referral center in Okinawa, Japan. We reviewed the records of all patients aged 15 years or older who were admitted to the Division of Infectious Diseases between 1995 and 2015 and finally diagnosed with bacterial (n = 34) or aseptic meningitis (n = 97). For bacterial meningitis, we compared the treatments that were actually selected based on PCGS with simulated treatments that would have been based on the Japanese guidelines. For aseptic meningitis, we compared the rates of antibiotic use between real cases where PCGS was available and real cases where it was not. RESULTS: PCGS was the most precise predictor for differentiating between bacterial and aseptic meningitis (sensitivity 91.2%, specificity 98.9%), being superior in this regard to medical histories, vital signs and physical examinations, and laboratory data available in the emergency room (ER). In bacterial meningitis, PCGS reduced the frequency of meropenem use (1/34 = 3.0%) compared with simulated cases in which PCGS was not available (19/34 = 55.9%) (p< 0.001). In aseptic meningitis cases, the rate of antibiotic administration was lower when PCGS was used (38/97 = 39.2%) than when it was not (45/74 = 60.8%) (p = 0.006). CONCLUSIONS: PCGS of CSF distinguishes between bacterial and aseptic meningitis more accurately than other predictors available in the ER. Patients with bacterial meningitis are more likely to receive narrower-spectrum antimicrobials when PCGS is used than when it is not. PCGS of CSF thus can potentially suppress the empiric use of antimicrobials for aseptic meningitis.

Step-like dependence of memory function on pulse width in spintronics reservoir computing.

Physical reservoir computing is a type of recurrent neural network that applies the dynamical response from physical systems to information processing. However, the relation between computation performance and physical parameters/phenomena still remains unclear. This study reports our progress regarding the role of current-dependent magnetic damping in the computational performance of reservoir computing. The current-dependent relaxation dynamics of a magnetic vortex core results in an asymmetric memory function with respect to binary inputs. A fast relaxation caused by a large input leads to a fast fading of the input memory, whereas a slow relaxation by a small input enables the reservoir to keep the input memory for a relatively long time. As a result, a step-like dependence is found for the short-term memory and parity-check capacities on the pulse width of input data, where the capacities remain at 1.5 for a certain range of the pulse width, and drop to 1.0 for a long pulse-width limit. Both analytical and numerical analyses clarify that the step-like behavior can be attributed to the current-dependent relaxation time of the vortex core to a limit-cycle state.