Experimental demonstration of quantum digital signatures over 43 dB channel loss using differential phase shift quantum key distribution.

Ensuring the integrity and transferability of digital messages is an important challenge in modern communications. Although purely mathematical approaches exist, they usually rely on the computational complexity of certain functions, in which case there is no guarantee of long-term security. Alternatively, quantum digital signatures offer security guaranteed by the physical laws of quantum mechanics. Prior experimental demonstrations of quantum digital signatures in optical fiber have typically been limited to operation over short distances and/or operated in a laboratory environment. Here we report the experimental transmission of quantum digital signatures over channel losses of up to 42.8 ± 1.2 dB in a link comprised of 90 km of installed fiber with additional optical attenuation introduced to simulate longer distances. The channel loss of 42.8 ± 1.2 dB corresponds to an equivalent distance of 134.2 ± 3.8 km and this represents the longest effective distance and highest channel loss that quantum digital signatures have been shown to operate over to date. Our theoretical model indicates that this represents close to the maximum possible channel attenuation for this quantum digital signature protocol, defined as the loss for which the signal rate is comparable to the dark count rate of the detectors.

Plasma presepsin level is an early diagnostic marker of severe febrile neutropenia in hematologic malignancy patients.

BACKGROUND: Febrile neutropenia (FN) is a common infectious complication in chemotherapy. The mortality of FN is higher in hematologic malignancy patients, and early diagnostic marker is needed. Presepsin is a prompt and specific marker for bacterial sepsis, but its efficacy in severe febrile neutropenia (FN) is not well confirmed. We tried to clarify whether it is a useful maker for early diagnosis of FN in patients during massive chemotherapy. METHODS: We measured plasma presepsin levels every 2-3 day in FN cases and evaluated its change during the course of massive chemotherapy. The patients had hematologic malignancy or bone marrow failure, and in all cases, neutropenia was severe during the episode. The baseline levels, onset levels, increase rate at FN onset, and onset / baseline ratio were evaluated for their efficacy of early FN diagnosis. RESULTS: Eleven episodes of bacteremia (six gram negatives and five gram positives) in severe neutropenia were analyzed in detail. While plasma presepsin level was strongly associated to the CRP level (r = 0.61, p < 0.01), it was not associated with the absolute WBC count (r = -0.19, p = 0.19), absolute neutrophil count (r = -0.11, p = 0.41) or absolute monocyte count (r = -0.12, p = 0.40). The average of onset presepsin level was 638 ± 437 pg/mL and the cutoff value (314 pg/mL) has detected FN onset in 9 of 11 cases. The two cases undetected by presepsin were both Bacillus species bacteremia. CONCLUSIONS: Plasma presepsin level is a reliable marker of FN even in massive chemotherapy with very low white blood cell counts. Closer monitoring of this molecule could be a help for early diagnosis in FN. But bacteremia caused by Bacillus species was an exception in our study.

Experimental transmission of quantum digital signatures over 90 km of installed optical fiber using a differential phase shift quantum key distribution system.

Quantum digital signatures (QDSs) apply quantum mechanics to the problem of guaranteeing message integrity and non-repudiation with information-theoretical security, which are complementary to the confidentiality realized by quantum key distribution (QKD). Previous experimental demonstrations have been limited to transmission distances of less than 5 km of optical fiber in a laboratory setting. Here we report, to the best of our knowledge, the first demonstration of QDSs over installed optical fiber, as well as the longest transmission link reported to date. This demonstration used a 90 km long differential phase shift QKD to achieve approximately one signed bit per second, an increase in the signature generation rate of several orders of magnitude over previous optical fiber demonstrations.

Mycobacterium shigaense Causes Lymph Node and Cutaneous Lesions as Immune Reconstitution Syndrome in an AIDS Patient: The Third Case Report of a Novel Strain Non-tuberculous Mycobacterium.

A 40-year-old man complaining of progressive body weight loss was diagnosed to have acquired immunodeficiency syndrome. Within 2 weeks after the initiation of combination antiretroviral therapy, he developed fever, massive cervical lymphadenopathy and a protruding subcutaneous abscess. A lymph node biopsy and abscess drainage revealed non-caseous granuloma and mycobacterium. The mycobacterium belonged to Runyon II group, but it showed no matches to any previously reported species. According to sequence analyses, the strain was identified as Mycobacterium shigaense. After six months of antimycobacterial treatment, the lesions were all successfully cured. This is the third case report of the novel mycobacterium, M. shigaense, presenting in associatioin with immune reconstitution syndrome.

Ultimate low system dark-count rate for superconducting nanowire single-photon detector.

The dark-count rate (DCR) is a key parameter of single-photon detectors. By introducing a bulk optical band-pass filter mounted on a fiber-to-fiber optical bench cooled at 3 K and blocking down to 5 µm, we suppressed the DCR of a superconducting nanowire single-photon detector by more than three orders of magnitude. The DCR is limited by the blackbody radiation through a signal passband of 20-nm bandwidth. The figure of merit, system detection efficiency, and DCR were 2.7×10(11), 2.3%, and 10(-3) Hz, respectively. Narrowing the bandwidth to 100 GHz suppresses the DCR to 10(-4) Hz, and the figure of merit increases to 1.8×10(12).

Gender differences in predictors of left ventricular myocardial relaxation in non-obese, healthy individuals.

BACKGROUND: Previous studies indicate that individuals with metabolic syndrome (MetS) might be at risk for left ventricular (LV) diastolic dysfunction. However, little is known about which metabolic factors contribute to the development of LV dysfunction in individuals who are not obese or overweight and who do not have diabetes mellitus and/or cardiovascular disease. METHODS: Participants without diabetes mellitus, systolic dysfunction, or other heart diseases underwent a thorough physical examination, including tissue Doppler echocardiography. A peak early mitral annular velocity (e') of <5.0 was designated as indicating abnormal LV myocardial relaxation (LVMR). We performed single and multiple logistic regression analyses of e' and cardiovascular risk factors, including MetS factors and indicators of major organ dysfunction. Normal-weight subjects (body mass index <25 kg/m2) were also analyzed. RESULTS: A total of 1055 individuals (mean age, 63 ± 13 years) participated, of which 307 (29.1%) had MetS and 199 (18.9%) had abnormal LVMR. Multiple logistic regression analysis revealed waist circumference (WC) (odds ratio [OR] 1.04, P < 0.05) and age (OR 1.10, P < 0.05) to be predictors of abnormal LVMR. In normal-weight subjects (n = 806), aging (OR 1.08, P < 0.01), abnormal WC (OR 3.80, P < 0.01), and renal dysfunction (OR 2.14, P < 0.01) were predictors of abnormal LVMR. Among MetS factors, abnormal WC in men (OR 3.70, P < 0.01) and high diastolic blood pressure (DBP) in women (OR 4.00, P = 0.01) were related to abnormal LVMR.

Identifying a correlated spin fluctuation in an entangled spin chain subject to a quantum phase transition.

This paper presents a theoretical framework for analyzing the quantum fluctuation properties of a quantum spin chain subject to a quantum phase transition. We can quantify the fluctuation properties by examining the correlation between the fluctuations of two neighboring spins subject to the quantum uncertainty. To do this, we first compute the reduced density matrix ρ of the spin pair from the ground state |Ψ⟩ of a spin chain, and then identify the quantum correlation part ρ(q) embedded in ρ. If the spin chain is translationally symmetric and characterized by a nearest-neighbor two-body spin interaction, we can determine uniquely the form of ρ(q) as W|Φ〉〈Φ| with the weight W ≤1, and quantify the fluctuation properties using the two-spin entangled state |Φ〉. We demonstrate the framework for a transverse-field quantum Ising spin chain and indicate its validity for more general spin chain models.

Quantum key distribution over a 72 dB channel loss using ultralow dark count superconducting single-photon detectors.

We report the first quantum key distribution (QKD) experiment over a 72 dB channel loss using superconducting nanowire single-photon detectors (SSPD, SNSPD) with the dark count rate (DCR) of 0.01 cps. The DCR of the SSPD, which is dominated by the blackbody radiation at room temperature, is blocked by introducing cold optical bandpass filter. We employ the differential phase shift QKD (DPS-QKD) scheme with a 1 GHz system clock rate. The quantum bit error rate (QBER) below 3% is achieved when the length of the dispersion shifted fiber (DSF) is 336 km (72 dB loss), which is low enough to generate secure keys.

Factors increasing physical activity levels in diabetes mellitus: a survey of patients after an inpatient diabetes education program.

[Purpose] The aim of this study was to understand the factors involved in increasing physical activity levels in type 2 diabetes mellitus patients for improved glycemic control. [Subjects] The subjects were 101 type 2 diabetes mellitus patients who had completed an inpatient diabetes education program. [Methods] The survey evaluated physical activity levels on the basis of the International Physical Activity Questionnaire and a questionnaire listing physical and psychosocial factors. [Results] Four variables-participation or non-participation in farm work, presence or absence of a job, stage of change in attitude toward exercise behavior, and social support-accounted for 34% of physical activity levels in these diabetes mellitus patients. The Spearman's rank correlation coefficient between physical activity level and HbA1c was -0.31. [Conclusion] Intervention in terms of practical use of living environments, promotion of exercise behavior, and social support may be effective in helping to improve glycemic control.

Slow light enhanced correlated photon pair generation in photonic-crystal coupled-resonator optical waveguides.

We demonstrate the generation of quantum-correlated photon pairs from a Si photonic-crystal coupled-resonator optical waveguide. A slow-light supermode realized by the collective resonance of high-Q and small-mode-volume photonic-crystal cavities successfully enhanced the efficiency of the spontaneous four-wave mixing process. The generation rate of photon pairs was improved by two orders of magnitude compared with that of a photonic-crystal line defect waveguide without a slow-light effect.

Countermeasure against tailored bright illumination attack for DPS-QKD.

We propose a countermeasure against the so-called tailored bright illumination attack for differential-phase-shift QKD (DPS-QKD). By monitoring a rate of coincidence detection at a pair of superconducting nanowire single-photon detectors (SSPDs) which is connected at each of the output ports of Bob's Mach-Zehnder interferometer, Alice and Bob can detect and defeat this kind of attack. We also experimentally confirmed the feasibility of this countermeasure using our 1 GHz-clocked DPS-QKD system. In the emulation of the attack, we achieved much lower power of the bright illumination light compared with the original demonstration by using a pulse stream instead of broad pulses.

Characteristics of superconducting single photon detector in DPS-QKD system under bright illumination blinding attack.

We derive the time-dependent photo-detection probability equation of a superconducting single photon detector (SSPD) to study the responsive property for a pulse train at high repetition rate. Using this equation, we analyze the characteristics of SSPDs when illuminated by bright pulses in blinding attack on a quantum key distribution (QKD). We obtain good agreement between expected values based on our equation and actual experimental values. Such a time-dependent probability analysis contributes to security analysis.

A monolithically integrated polarization entangled photon pair source on a silicon chip.

Integrated photonic circuits are one of the most promising platforms for large-scale photonic quantum information systems due to their small physical size and stable interferometers with near-perfect lateral-mode overlaps. Since many quantum information protocols are based on qubits defined by the polarization of photons, we must develop integrated building blocks to generate, manipulate, and measure the polarization-encoded quantum state on a chip. The generation unit is particularly important. Here we show the first integrated polarization-entangled photon pair source on a chip. We have implemented the source as a simple and stable silicon-on-insulator photonic circuit that generates an entangled state with 91 ± 2% fidelity. The source is equipped with versatile interfaces for silica-on-silicon or other types of waveguide platforms that accommodate the polarization manipulation and projection devices as well as pump light sources. Therefore, we are ready for the full-scale implementation of photonic quantum information systems on a chip.

Case of muscle abscess due to disseminated nocardiosis in a patient with autoimmune hemolytic anemia, and review of the published work.

Although disseminated nocardiosis has been increasing with the expansion of immunosuppressive therapy and improvement in diagnostic methods, muscle abscess is a rare complication. There have been only nine case reports of muscle abscess due to Nocardia infection in the English-language published work. We present a case of muscle abscess with disseminated nocardiosis, and review the published work. The patient had been taking prednisolone at 20 mg a day for autoimmune hemolytic anemia for 14 years. She presented with erythema on her thigh resembling cellulitis. Computed tomography showed muscle abscess. The isolated organism was identified as Nocardia farcinica employing polymerase chain reaction and antibiotic sensitivity testing. The diagnosis of muscle abscess due to nocardiosis can be easily missed because there are no characteristic symptoms.

Cooling an optical fiber to 4.5 K by indirect thermal contact with a liquid-helium flow and spectroscopic temperature measurements.

We have made it possible to cool a 10-m-long optical fiber to 4.5 K in a compact helium-flow cryostat. The cryostat is vacuum loaded and the cooling principle is based on thermal contact with a copper holder cooled by the liquid-helium flow. To measure the temperature directly, we employed two different spectroscopic methods depending on the temperature regions. One was photon-counting Raman spectroscopy and the other was Brillouin spectroscopy. We used certain devices to improve the cooling efficiency and confirmed that the fiber was uniformly cooled to 4.5 K.

Validity of childhood disintegrative disorder apart from autistic disorder with speech loss.

In order to test clinical validity of DSM-IV childhood disintegrative disorder (CDD), 10 CDD children (mean age = 8.2 years, SD = 3.8; 7 male and 3 female) and 30 age- and gender-matched children with DSM-IV autistic disorder (AD) with speech loss (SL) (ADSL) were compared on 24 variables not directly related to CDD criteria. Compared with the ADSL children, the CDD children showed fearfulness significantly more frequently during the period of SL; displayed epilepsy significantly more frequently and stereotypy significantly more prominently at first visit on average about 6 years after SL; and had significantly less uneven intellectual profile at first visit to support the validity of CDD to a certain extent. No significant difference in the retardation level at first visit between the two groups suggested no worse short-term outcome in CDD than ADSL, although a long-term prospective study to compare them from infancy is needed.

Validity of DQ as an estimate of IQ in children with autistic disorder.

The purpose of the present paper was to test the validity of developmental quotients (DQ) on the Mental Development Scale for Infants and Young Children (MDSIYC) as an estimate of intelligence quotient (IQ). Correlations were carried out of its DQ with an IQ on the Japanese version of the Stanford-Binet in 94 children with Diagnostic and Statistical Manual of Mental Disorders (4th edn; DSM-IV) autistic disorder. With IQ, DQ in the five MDSIYC areas (motor, play, socialization, self-help, and speech) and full-scale DQ (mean of five-area DQ) had significant correlations (Pearson r) of 0.46, 0.56, 0.53, 0.46, 0.85, and 0.68, respectively, suggesting that speech DQ is the most valid estimate of IQ.

Enzymatic synthesis of oligosaccharide containing Le(x) unit by using partially purified chicken serum.

Animal sera were screened for an alternative enzyme source of alpha1,3-fucosyltransferase, and the highest activity was observed in chicken serum. A partially purified enzyme fraction almost devoid of coexisting glycosidases was prepared from the chicken serum, and used for the fucosylation of LacNAc compounds. The enzyme reaction was efficient enough to allow the one-pot preparation of designed Le(x) compounds such as LNFP III.