Temporal pattern recognition with delayed feedback spin-torque nano-oscillators.

The recent demonstration of neuromorphic computing with spin-torque nano-oscillators has opened a path to energy efficient data processing. The success of this demonstration hinged on the intrinsic short-term memory of the oscillators. In this study, we extend the memory of the spin-torque nano-oscillators through time-delayed feedback. We leverage this extrinsic memory to increase the efficiency of solving pattern recognition tasks that require memory to discriminate different inputs. The large tunability of these non-linear oscillators allows us to control and optimize the delayed feedback memory using different operating conditions of applied current and magnetic field.

Vector network analyzer ferromagnetic resonance spectrometer with field differential detection.

This work presents a vector network analyzer ferromagnetic resonance (VNA-FMR) spectrometer with field differential detection. This technique differentiates the S-parameter by applying a small binary modulation field in addition to the DC bias field to the sample. By setting the modulation frequency sufficiently high, slow sensitivity fluctuations of the VNA, i.e., low-frequency components of the trace noise, which limit the signal-to-noise ratio of the conventional VNA-FMR spectrometer, can be effectively removed, resulting in a very clean FMR signal. This paper presents the details of the hardware implementation and measurement sequence as well as the data processing and analysis algorithms tailored for the FMR spectrum obtained with this technique. Because the VNA measures a complex S-parameter, it is possible to estimate the Gilbert damping parameter from the slope of the phase variation of the S-parameter with respect to the bias field. We show that this algorithm is more robust against noise than the conventional algorithm based on the linewidth.

Mutual synchronization of spin torque nano-oscillators through a long-range and tunable electrical coupling scheme.

The concept of spin-torque-driven high-frequency magnetization dynamics, allows the potential construction of complex networks of non-linear dynamical nanoscale systems, combining the field of spintronics and the study of non-linear systems. In the few previous demonstrations of synchronization of several spin-torque oscillators, the short-range nature of the magnetic coupling that was used has largely hampered a complete control of the synchronization process. Here we demonstrate the successful mutual synchronization of two spin-torque oscillators with a large separation distance through their long range self-emitted microwave currents. This leads to a strong improvement of both the emitted power and the linewidth. The full control of the synchronized state is achieved at the nanoscale through two active spin transfer torques, but also externally through an electrical delay line. These additional levels of control of the synchronization capability provide a new approach to develop spin-torque oscillator-based nanoscale microwave-devices going from microwave-sources to bio-inspired networks.

Chromosomal anomalies and sperm retrieval outcomes of patients with non-obstructive azoospermia: a case series.

Some preoperative factors affecting the outcome of microdissection testicular sperm extraction (micro-TESE) have been previously evaluated. However, other than Klinefelter syndrome (KS), no other chromosomal anomalies have been discussed in the context of sperm retrieval outcomes. The objective of this study was to describe chromosomal anomalies and their relationship with sperm retrieval outcomes in patients with non-obstructive azoospermia (NOA). Of the 197 NOA patients whose clinical records were retrospectively reviewed, 144 (73.1%) had normal 46,XY karyotype, 40 (20.3%) had KS (47,XXY), and 13 (6.6%) had other chromosomal anomalies (autosomal in seven cases and sex-chromosomal anomalies in six). Of the seven patients with autosomal anomalies, two had the reportedly normal variant 46,XY,inv(9)(p12;q13). Testicular volume and serum hormone levels (luteinizing hormone, follicle-stimulating hormone, and total testosterone) of the patients with chromosomal anomalies other than KS were comparable to those of the patients with normal karyotype. The sperm retrieval rate of the patients with 46,XY karyotype, KS, or other chromosomal anomalies were 27.1%, 22.5%, and 15.4%, respectively, with no statistically significant difference. However, among the samples collected from the 13 patients with chromosomal anomalies other than KS, only those from the two patients with the normal variant 46,XY,inv(9)(p12;q13) contained spermatozoa. Among our series of NOA patients, the incidence of autosomal anomalies was higher than that generally noted among neonates, which suggests that not only sex-chromosomal anomalies but also autosomal anomalies may affect the development of NOA. Furthermore, our findings suggest that sperm retrieval outcome is more unfavorable in NOA patients with chromosomal anomalies than in NOA patients with 46,XY karyotype or KS, despite the use of micro-TESE.

Neuromorphic Computing through Time-Multiplexing with a Spin-Torque Nano-Oscillator.

Fabricating powerful neuromorphic chips the size of a thumb requires miniaturizing their basic units: synapses and neurons. The challenge for neurons is to scale them down to submicrometer diameters while maintaining the properties that allow for reliable information processing: high signal to noise ratio, endurance, stability, reproducibility. In this work, we show that compact spin-torque nano-oscillators can naturally implement such neurons, and quantify their ability to realize an actual cognitive task. In particular, we show that they can naturally implement reservoir computing with high performance and detail the recipes for this capability.

Coherent microwave generation by spintronic feedback oscillator.

The transfer of spin angular momentum to a nanomagnet from a spin polarized current provides an efficient means of controlling the magnetization direction in nanomagnets. A unique consequence of this spin torque is that the spontaneous oscillations of the magnetization can be induced by applying a combination of a dc bias current and a magnetic field. Here we experimentally demonstrate a different effect, which can drive a nanomagnet into spontaneous oscillations without any need of spin torque. For the demonstration of this effect, we use a nano-pillar of magnetic tunnel junction (MTJ) powered by a dc current and connected to a coplanar waveguide (CPW) lying above the free layer of the MTJ. Any fluctuation of the free layer magnetization is converted into oscillating voltage via the tunneling magneto-resistance effect and is fed back into the MTJ by the CPW through inductive coupling. As a result of this feedback, the magnetization of the free layer can be driven into a continual precession. The combination of MTJ and CPW behaves similar to a laser system and outputs a stable rf power with quality factor exceeding 10,000.

Identification and functional activity of a staphylocoagulase type XI variant originating from staphylococcal food poisoning isolates.

UNLABELLED: Staphylocoagulase, an extracellular protein secreted by Staphylococcus aureus, has been used as an epidemiological marker. At least 12 serotypes and 24 genotypes subdivided on the basis of nucleotide sequence have been reported to date. In this study, we identified a novel staphylocoagulase nucleotide sequence, coa310, from staphylococcal food poisoning isolates that had the ability to coagulate plasma, but could not be typed using the conventional method. The protein encoded by coa310 contained the six fundamental conserved domains of staphylocoagulase. The full-length nucleotide sequence of coa310 shared the highest similarity (77·5%) with that of staphylocoagulase-type (SCT) XIa. The sequence of the D1 region, which would be responsible for the determination of SCT, shared the highest similarity (91·8%) with that of SCT XIa. These results suggest that coa310 is a novel variant of SCT XI. Moreover, we demonstrated that coa310 encodes a functioning coagulase, by confirming the coagulating activity of the recombinant protein expressed from coa310. This is the first study to directly demonstrate that Coa310, a putative SCT XI, has coagulating activity. These findings may be useful for the improvement of the staphylocoagulase-typing method, including serotyping and genotyping. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study to identify a novel variant of staphylocoagulase type XI based on its nucleotide sequence and to demonstrate coagulating activity in the variant using a recombinant protein. Elucidation of the variety of staphylocoagulases will provide suggestions for further improvement of the staphylocoagulase-typing method and contribute to our understanding of the epidemiologic characterization of Staphylococcus aureus.

Spin-torque resonant expulsion of the vortex core for an efficient radiofrequency detection scheme.

It has been proposed that high-frequency detectors based on the so-called spin-torque diode effect in spin transfer oscillators could eventually replace conventional Schottky diodes due to their nanoscale size, frequency tunability and large output sensitivity. Although a promising candidate for information and communications technology applications, the output voltage generated from this effect has still to be improved and, more pertinently, reduces drastically with decreasing radiofrequency (RF) current. Here we present a scheme for a new type of spintronics-based high-frequency detector based on the expulsion of the vortex core in a magnetic tunnel junction (MTJ). The resonant expulsion of the core leads to a large and sharp change in resistance associated with the difference in magnetoresistance between the vortex ground state and the final C-state configuration. Interestingly, this reversible effect is independent of the incoming RF current amplitude, offering a fast real-time RF threshold detector.

Fish collagen is an important panallergen in the Japanese population.

Collagen was identified as a fish allergen in early 2000s. Although its allergenic potential has been suggested to be low, risks associated with collagen as a fish allergen have not been evaluated to a greater extent. In this study, we aimed to clarify the importance of collagen as a fish allergen. Our results showed that 50% of Japanese patients with fish allergy had immunoglobulin E (IgE) against mackerel collagen, whereas 44% had IgE against mackerel parvalbumin. IgE inhibition assay revealed high cross-reactivity of mackerel collagen to 22 fish species (inhibition rates: 87-98%). Furthermore, a recently developed allergy test demonstrated that collagen triggered IgE cross-linking on mast cells. These data indicate that fish collagen is an important and very common panallergen in fish consumed in Japan. The high rate of individuals' collagen allergy may be attributable to the traditional Japanese custom of raw fish consumption.

Understanding of Phase Noise Squeezing Under Fractional Synchronization of a Nonlinear Spin Transfer Vortex Oscillator.

We investigate experimentally the synchronization of vortex based spin transfer nano-oscillators to an external rf current whose frequency is at multiple integers, as well as at an integer fraction, of the oscillator frequency. Through a theoretical study of the locking mechanism, we highlight the crucial role of both the symmetries of the spin torques and the nonlinear properties of the oscillator in understanding the phase locking mechanism. In the locking regime, we report a phase noise reduction down to -90 dBc/Hz at 1 kHz offset frequency. Our demonstration that the phase noise of these nanoscale nonlinear oscillators can be tuned and eventually lessened, represents a key achievement for targeted radio frequency applications using spin torque devices.

Identification and characterization of novel Staphylococcus aureus pathogenicity islands encoding staphylococcal enterotoxins originating from staphylococcal food poisoning isolates.

AIMS: Horizontal transfer of Staphylococcus aureus pathogenicity islands (SaPIs) plays an important role in acquiring pathogenicity. This study aimed to identify novel SaPIs encoding staphylococcal enterotoxins (SEs) and to characterize their SE productivity and replication process. METHODS AND RESULTS: Four novel SaPIs (SaPITokyo12413, SaPITokyo11212, SaPITokyo12571 and SaPITokyo12381) were determined using the SaPI scanning method. These SaPIs were composed of mosaic structures containing reported sequences. Four strains harbouring novel SaPIs produced significant amounts of SEs to cause staphylococcal food poisoning (SFP). With focus on the interaction between the replication initiator protein (Rep) and the replication origin (ori sites) that are proposed to be important for the replication of SaPIs, each Rep was prepared and their two functions were confirmed: binding activity to ori sites and helicase activity. These activities were present in the Reps of SaPITokyo11212, SaPITokyo12571 and SaPITokyo12381, but were both absent in the Rep of SaPITokyo12413. CONCLUSIONS: All four novel SaPIs could give sufficient toxicity to Staph. aureus to cause SFP. However, SaPITokyo12413 may be restricted in its replication capacity, suggesting that it lacks transfer ability unlike the other SaPIs. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report to identify four novel SE-encoding SaPIs and to examine their toxicity and replication capacity. Because SaPIs deeply participate in SE acquisition, it is important to elucidate their characteristics for understanding Staph. aureus virulence and speculating regarding its evolution as a pathogen.

Increased prevalence of group A streptococcus isolates in streptococcal toxic shock syndrome cases in Japan from 2010 to 2012.

Streptococcal toxic shock syndrome (STSS) is a severe invasive infection characterized by the sudden onset of shock, multi-organ failure, and high mortality. In Japan, appropriate notification measures based on the Infectious Disease Control law are mandatory for cases of STSS caused by ß-haemolytic streptococcus. STSS is mainly caused by group A streptococcus (GAS). Although an average of 60-70 cases of GAS-induced STSS are reported annually, 143 cases were recorded in 2011. To determine the reason behind this marked increase, we characterized the emm genotype of 249 GAS isolates from STSS patients in Japan from 2010 to 2012 and performed antimicrobial susceptibility testing. The predominant genotype was found to be emm1, followed by emm89, emm12, emm28, emm3, and emm90. These six genotypes constituted more than 90% of the STSS isolates. The number of emm1, emm89, emm12, and emm28 isolates increased concomitantly with the increase in the total number of STSS cases. In particular, the number of mefA-positive emm1 isolates has escalated since 2011. Thus, the increase in the incidence of STSS can be attributed to an increase in the number of cases associated with specific genotypes.

Multilocus sequence typing of bifidobacterial strains from infant's faeces and human milk: are bifidobacteria being sustainably shared during breastfeeding?

Bifidobacteria are considered to be one of the most important beneficial intestinal bacteria for infants, contributing to the priming of the mucosal immune system. These microbes can also be detected in mother's milk, suggesting a potential role of human milk in the colonisation of infant's gut. However, little is known about the timing of bacteria appearance in human milk, and whether human milk is the first source of inoculation. Here, we investigated whether specific strains are shared sustainably between maternal milk and infant's gut. Faecal samples and human milk were collected from 102 healthy mother-infant pairs (infant's faeces: meconium, 7, 30 days of age; mother's milk: once before delivery, colostrum, 7, 30 days after delivery). Bifidobacterial strains were isolated from these samples, and were discriminated by means of multilocus sequencing typing. No bifidobacteria were detected from human milk collected before delivery, or colostrum. Strains were isolated only from human milk samples obtained 7 days after birth or later. On the other hand, bifidobacterial strains were obtained from infant's faeces throughout the study period, sometimes as early as the first day of life (meconium). We have found that bifidobacterial species belonging to Bifidobacterium bifidum, Bifidobacterium breve, and Bifidobacterium longum subsp. longum could be identified as monophyletic between infant's faeces and their mother's milk. These strains were confirmed to be sustainably shared between maternal milk and infant's gut. Moreover, monophyletic strains were isolated at the same time point or earlier from infant's faeces than from human milk, and none were isolated earlier from human milk than from infant's faeces. Although it remains unclear whether human milk is the first source of microbes for infants, our results confirm that human milk is a reservoir of bifidobacteria, and specific strains are shared between infant's intestine and human milk during breastfeeding.

Effect of fermented milk containing Lactobacillus casei strain Shirota on constipation-related symptoms and haemorrhoids in women during puerperium.

Constipation and haemorrhoids are common complaints after childbirth. The objective of this pilot study was to evaluate impact of fermented milk containing Lactobacillus casei strain Shirota (LcS) on stool consistency and frequency, constipation-related symptoms and quality of life, and incidence of haemorrhoids in women during puerperium. Forty women who had natural childbirth were randomised to group consuming either one bottle/day of fermented milk containing at least 6.5×109 cfu of LcS, or placebo, for 6 weeks after childbirth. Subjects filled in a diary on their bowel habits including number of bowel movement, stool consistency and incidence of haemorrhoids, and answered questionnaires on constipation-related symptoms (PAC-SYM) and quality of life (PAC-QOL) during the study period. The probiotic group showed the better scores on overall PAC-SYM (P=0.013), PAC-SYM subscales of abdominal symptoms (P=0.043) and rectal symptoms (P=0.031), and PAC-QOL satisfaction subscale (P=0.037) in comparison with the placebo group. In the probiotic group, two to four subjects experienced haemorrhoids during the first 3 weeks of treatment. The number decreased in week 4 and no one had haemorrhoids on most days in week 5-6. In the placebo group, on average four subjects had haemorrhoids from the beginning, and no obvious change was observed until week 6. No statistically significant effect was observed on stool consistency and frequency. The study products did not cause any adverse event in the subjects. Results of this study indicate that continuous consumption of fermented milk containing LcS might alleviate constipation-related symptoms, provide satisfactory bowel habit and result in earlier recovery from haemorrhoids in women during puerperium. Nonetheless, there are several limitations in interpretation of the results attributed to the study design, including lack of baseline data. Further study is required in order to confirm the efficacy.

Incidence of and risk factors for incisional hernia after abdominal surgery.

BACKGROUND: Few larger studies have estimated the incidence of incisional hernia (IH) after abdominal surgery. METHODS: Patients who had abdominal surgery between November 2009 and February 2011 were included in the study. The incidence rate and risk factors for IH were monitored for at least 180 days. RESULTS: A total of 4305 consecutive patients were registered. Of these, 378 were excluded because of failure to complete follow-up and 3927 patients were analysed. IH was diagnosed in 318 patients. The estimated incidence rates for IH were 5·2 per cent at 12 months and 10·3 per cent at 24 months. In multivariable analysis, wound classification III and IV (hazard ratio (HR) 2·26, 95 per cent confidence interval 1·52 to 3·35), body mass index of 25 kg/m(2) or higher (HR 1·76, 1·35 to 2·30), midline incision (HR 1·74, 1·28 to 2·38), incisional surgical-site infection (I-SSI) (HR 1·68, 1·24 to 2·28), preoperative chemotherapy (HR 1·61, 1·08 to 2·37), blood transfusion (HR 1·46, 1·04 to 2·05), increasing age by 10-year interval (HR 1·30, 1·16 to 1·45), female sex (HR 1·26, 1·01 to 1·59) and thickness of subcutaneous tissue for every 1-cm increase (HR 1·18, 1·03 to 1·35) were identified as independent risk factors. Compared with superficial I-SSI, deep I-SSI was more strongly associated with the development of IH. CONCLUSION: Although there are several risk factors for IH, reducing I-SSI is an important step in the prevention of IH. REGISTRATION NUMBER: UMIN000004723 (University Hospital Medical Information Network, http://www.umin.ac.jp/ctr/index.htm).

Highly sensitive nanoscale spin-torque diode.

Highly sensitive microwave devices that are operational at room temperature are important for high-speed multiplex telecommunications. Quantum devices such as superconducting bolometers possess high performance but work only at low temperature. On the other hand, semiconductor devices, although enabling high-speed operation at room temperature, have poor signal-to-noise ratios. In this regard, the demonstration of a diode based on spin-torque-induced ferromagnetic resonance between nanomagnets represented a promising development, even though the rectification output was too small for applications (1.4 mV mW(-1)). Here we show that by applying d.c. bias currents to nanomagnets while precisely controlling their magnetization-potential profiles, a much greater radiofrequency detection sensitivity of 12,000 mV mW(-1) is achievable at room temperature, exceeding that of semiconductor diode detectors (3,800 mV mW(-1)). Theoretical analysis reveals essential roles for nonlinear ferromagnetic resonance, which enhances the signal-to-noise ratio even at room temperature as the size of the magnets decreases.

The development and initial validation of a virtual dripping sweat rate and a clothing wetness ratio for use in predictive heat strain models.

This paper applies the heat balance equation (HBE) for clothed subjects as a linear function of mean skin temperature (t sk ) by a new sweating efficiency (η sw ) and an approximation for the thermoregulatory sweat rate. The equation predicting t sk in steady state conditions was derived as the solution of the HBE and used for a predictive heat strain scale. The heat loss from the wet clothing (WCL) area was identified with a new variable of 'virtual dripping sweat rate VDSR' (S wdr ). This is a subject's un-evaporated sweat rate in dry clothing from the regional sweat rate exceeding the maximum evaporative capacity, and adds the moisture to the clothing, reducing the intrinsic clothing insulation. The S wdr allowed a mass balance analysis of the wet clothing area identified as clothing wetness (w cl ). The w cl was derived by combining the HBE at the WCL surface from which the evaporation rate and skin heat loss from WCL region are given. Experimental results on eight young male subjects wearing typical summer clothing, T-shirt and trousers verified the model for predicting t sk with WCL thermal resistance (R cl,w ) identified as 25 % of dry clothing (R cl,d ).

Prediction of mean skin temperature for use as a heat strain scale by introducing an equation for sweating efficiency.

The present paper made the heat balance equation (HBE) for nude or minimally clad subjects a linear function of mean skin temperature (t(sk)) by applying new equations for sweating efficiency (η(sw)) and thermoregulatory sweat rate (S(wR)). As the solution of the HBE, the equation predicting t(sk) was derived and used for a heat strain scale of subjects. The η(sw) was proportional to the reciprocal of S(w)/E(max) (S(w), sweat rate; E(max) maximum evaporative capacity) and the S(wR) was proportional to t(sk) with a parameter of the sweating capacity of the subject. The errors of predicted t(sk) from observations due to the approximation of η(sw) were examined based on experimental data conducted on eight young male subjects. The value of errors of t(sk) was -0.10 ± 0.42 °C (mean ± sample standard deviation (SSD)). We aim to apply the predicted t(sk) of a subject at a level of sweating capacity as a heat strain scale of a function of four environmental factors (dry- and wet-bulb temperatures, radiation, and air velocity) and three human factors (metabolic rate, sweating capacity, and clothing (≤0.2clo)).