Efficient and low-noise single-photon detection in 1550 nm communication band by frequency upconversion in periodically poled LiNbO3 waveguides

We demonstrate 1500 nm band single-photon detection with low dark-count noise and a potentially high efficiency, which may allow long distance and high-bit-rate quantum key distribution. By developing frequency upconversion devices based on periodically poled lithium niobate waveguides, which are specifically designed to use a pump wavelength longer than that of communication-band photons, we completely eliminate the dark-count noise caused by parasitic nonlinear processes in the waveguide. We observed an internal conversion efficiency as high as 40% and demonstrated scaling down to the single photon level while maintaining a background dark-count rate of 10(2)s(-1).

Effect of cervical sympathetic trunk transection on renal sympathetic nerve activity in rats

Stellate ganglion blockade (SGB) with a local anesthetic increases muscle sympathetic nerve activity in the tibial nerve in humans. However, whether this sympathetic excitation in the tibial nerve is due to a sympathetic blockade in the neck itself, or due to infiltration of a local anesthetic to adjacent nerves including the vagus nerve remains unknown. To rule out one mechanism, we examined the effects of cervical sympathetic trunk transection on renal sympathetic nerve activity (RSNA) in anesthetized rats. Seven rats were anesthetized with intraperitoneal urethane. RSNA together with arterial blood pressure and heart rate were recorded for 15 min before and 30 min after left cervical sympathetic trunk transection. The baroreceptor unloading RSNA obtained by decreasing arterial blood pressure with administration of sodium nitroprusside was also measured. Left cervical sympathetic trunk transection did not have any significant effects on RSNA, baroreceptor unloading RSNA, arterial blood pressure, and heart rate. These data suggest that there was no compensatory increase in RSNA when cervical sympathetic trunk was transected and that the increase in sympathetic nerve activity in the tibial nerve during SGB in humans may result from infiltration of a local anesthetic to adjacent nerves rather than a sympathetic blockade in the neck itself.

Field trial of differential-phase-shift quantum key distribution using polarization independent frequency up-conversion detectors

We report a field trial of differential phase shift quantum key distribution (QKD) using polarization independent frequency up-conversion detectors. A frequency up-conversion detector is a promising device for achieving a high key generation rate when combined with a high clock rate QKD system. However, its polarization dependence prevents it from being applied to practical QKD systems. In this paper, we employ a modified polarization diversity configuration to eliminate the polarization dependence. Applying this method, we performed a long-term stability test using a 17.6-km installed fiber. We successfully demonstrated stable operation for 6 hours and achieved a sifted key generation rate of 120 kbps and an average quantum bit error rate of 3.14 %. The sifted key generation rate was not the estimated value but the effective value, which means that the sifted key was continuously generated at a rate of 120 kbps for 6 hours.

Long-distance distribution of time-bin entangled photon pairs over 100 km using frequency up-conversion detectors

We report an experimental demonstration of the distribution of time-bin entangled photon pairs over 100 km of optical fiber. In our experiment, 1.5-mum non-degenerated time-bin entangled photon pairs were generated with a periodically poled lithium niobate (PPLN) waveguide by using the parametric down conversion process. Combining this approach with ultra-low-loss filters to eliminate the pump light and separate signal and idler photons, we obtained an efficient entangled photon pair source. To detect the photons, we used single-photon detectors based on frequency up-conversion. These detectors operated in a non-gated mode so that we could use a pulse stream of time correlated entangled photon pairs at a high repetition frequency (1 GHz). Using these elements, we distributed time-bin entangled photon pairs over 100 km of dispersion shifted fiber and performed a two-photon interference experiment. We obtained a coincidence fringe of 81.6% visibility without subtracting any background noise, such as accidental coincidence or dark count, which was good enough to violate Bell's inequality. Thus, we successfully distributed time-bin entangled photon pairs over 100 km.

Widely tunable 3.4 microm band difference frequency generation using apodized chi(2) grating

We achieved apodization in a quasi-phase-matched wavelength converter. The new design yields a large bandwidth and a flat phase-matching response with a high conversion efficiency. Using the method, we demonstrate widely tunable 3.4 microm band difference frequency generation in a LiNbO3 ridge waveguide.

Synergistic effects of meloxicam and conventional cytotoxic drugs in human MG-63 osteosarcoma cells

Cyclooxygenase-2 (COX-2) inhibitors have been shown to exert inhibitory effects on many types of malignant tumors and several groups have suggested that COX-2 inhibitors enhance the cytotoxic effects of other anti-cancer agents. We previously reported that meloxicam has an anti-tumorigenic effect on COX-2-expressing osteosarcoma cells. In the current study, we evaluated the synergy between meloxicam and cisplatin (CDDP), doxorubicin (DXR) and 4-hydroperoxy ifosfamide (4OOH-IFM), using the human osteosarcoma cell line, MG-63. Cytotoxicity was determined using 3-(4,5'-dimethylthiazol-2-yl)-2,5'-diphenyltetrazolium bromide (MTT) assays, and isobolographic analysis was used to evaluate any synergy. Apoptotic activity was determined by terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL), and by evaluating Bax and Bcl-2 expression levels using real-time RT-PCR and western blotting analysis. Cell cycling was evaluated by flow cytometry. The cytotoxic effects of CDDP and DXR were enhanced synergistically in the presence of meloxicam and were partially due to an increase in apoptosis. By contrast, meloxicam enhanced neither the cytotoxic nor the apoptotic activity of 4OOH-IFM. Combining meloxicam with DXR significantly up-regulated Bax expression, whereas it down-regulated Bcl-2 expression in combination with CDDP. Furthermore, the number of cells in the G2/M phase was significantly increased in DXR-treated samples by the addition of meloxicam, but not in CDDP-treated or 4OOH-IFM-treated samples. These results suggest a potential clinical application of meloxicam in combination with cytotoxic drugs in patients with COX-2-positive osteosarcoma.

Acute effect of oral phosphate loading on serum fibroblast growth factor 23 levels in healthy men

Serum fibroblast growth factor 23 (FGF23) is a novel phosphaturic factor and important for the regulation of inorganic phosphate (Pi) homeostasis. In this study, we examined an acute effect of oral Pi loading on serum FGF23 levels to clarify the role in rapid adjustment of serum Pi level. We performed a randomized, double-blind, crossover study in eight healthy male volunteers. The subjects were alternately served one of three test meals containing different Pi amounts (400 mg (P400), 800 mg (P800), and 1200 mg (P1200)) as lunch at noon. The postprandial changes in serum levels of Pi, Ca, 1,25-dihydroxyvitamin D, intact-parathyroid hormone (iPTH), intact-FGF23 (iFGF23), and urinary excretion of Pi and Ca until 8 h after Pi loading were estimated. Serum Pi levels and urinary Pi excretion significantly increased within 1 h after P400 and P800 intake. Serum iPTH levels at 1-2 and 4-6 h after P1200 intake was significantly higher than those of P400 intake. Serum iFGF23 levels slightly decreased up to 8 h after P400 intake and up to 6 h after P800 intake, but not changed in P1200 intake. Significant increase of iFGF23 was observed at 8 h after P1200 intake compared with both P400 and P800 intake. Additionally, negative association was detected between iFGF23 and serum Pi, whereas positive association was observed between iPTH and serum Pi during the short period. We conclude that oral Pi loading cannot rapidly increase serum FGF23 level. FGF23 may be not associated with rapid adaptation of Pi homeostasis.

Magnetic resonance spectroscopic determination of a neuronal and axonal marker in white matter predicts reversibility of deficits in secondary normal pressure hydrocephalus

BACKGROUND

Normal pressure hydrocephalus (NPH) is considered to be a treatable form of dementia, because cerebrospinal fluid (CSF) shunting can lessen symptoms. However, neuroimaging has failed to predict when shunting will be effective.

OBJECTIVE

To investigate whether 1H (proton) magnetic resonance (MR) spectroscopy could predict functional outcome in patients after shunting.

METHODS

Neurological state including Hasegawa's dementia scale, gait, continence, and the modified Rankin scale were evaluated in 21 patients with secondary NPH who underwent ventriculo-peritoneal shunting. Outcomes were measured postoperatively at one and 12 months and were classified as excellent, fair, or poor. MR spectra were obtained from left hemispheric white matter.

RESULTS

Significant preoperative differences in N-acetyl aspartate (NAA)/creatine (Cr) and NAA/choline (Cho) were noted between patients with excellent and poor outcome at one month (p = 0.0014 and 0.0036, respectively). Multiple regression analysis linked higher preoperative NAA/Cr ratio, gait score, and modified Rankin scale to better one month outcome. Predictive value, sensitivity, and specificity for excellent outcome following shunting were 95.2%, 100%, and 87.5%. Multiple regression analysis indicated that NAA/Cho had the best predictive value for one year outcome (p = 0.0032); predictive value, sensitivity, and specificity were 89.5%, 90.0%, and 88.9%.

CONCLUSIONS

MR spectroscopy predicted long term post-shunting outcomes in patients with secondary NPH, and it would be a useful assessment tool before lumbar drainage.

Propagation characteristics and guiding of a high-power microwave in plasma waveguide

The propagation characteristics of a high-power microwave [electromagnetic (em) wave] in a plasma waveguide are reported. The plasma waveguide is formed by expanding plasmas via the ponderomotive force of the high-power microwave and the microwave pulse remains trapped within the plasma waveguide and is guided in it. With the increase of the incident microwave power, the width of the plasma waveguide increases and the half width of the radial electric field distribution decreases. This shows that the em wave modifies the refractive index of the plasma waveguide area. For a plasma waveguide with narrower width, the microwave propagates along the plasma waveguide at the fundamental TE mode, while as the waveguide width increases the higher mode component starts appearing. Analytical treatment to the propagation of the electromagnetic wave in a dielectric waveguide having a step-index profile and the numerical calculations for the radial distribution of the electric field show fairly good agreement with the results observed in the present experiments.

Remodelling and healing process of moderately heat-treated bone grafts after wide resection of bone and soft-tissue tumors

INTRODUCTION

In the reconstruction of extensive bone defects after massive resection of malignant musculoskeletal tumors, the clinical results of moderately heat-treated autogenous bone graft have rarely been documented. We evaluated the remodelling and healing process of moderately heat-treated autogenous bone graft by means of imaging features.

MATERIALS AND METHODS

The subjects of this study were 19 patients with bone and soft-tissue tumors treated by heat-treated bone graft at our institution between 1992 and 2001, the mean follow-up period was 4.8+/-2.8 years (range 1-9 years). The remodelling and healing process of heat-treated bone graft was evaluated by means of radiography, bone scintigraphy, and MRI.

RESULTS

The mean period to obtain bone union between host bone and grafted bone was 9.4 months. Infection was noted in 1 patient, and fracture was present in 2 patients. In 6 patients, pseudoarthrosis was found. Bone scintigraphy showed an increased uptake at the host-graft junction in the period between 3 and 36 months (median 10.7 months) postoperatively. A gradually increased diffuse uptake on the grafted side was evident at an average of 29.1 months (range 19-41 months) postoperatively. High signal intensity on T2-weighted images was observed in the early period after surgery, and iso-intense or low signal intensity became evident after an average of 28.3 months. A gradually increased diffuse uptake on scintigraphy and iso-intense or low signal intensity on T2-weighted images indicated remodelling of the grafted bone.

CONCLUSION

Bone union of a moderately heat-treated autogenous bone graft was noted at about 9 months, and its remodelling was proceeding at about 30 months. This method will be useful for bone defects after massive resection of soft-tissue and bone tumors.

A study of inter-alpha-trypsin inhibitor chains expression in liposarcomas

AIM

Liposarcoma is common soft tissue sarcoma that is sometimes difficult to treat, besides its good prognosis. The inter-alpha-trypsin inhibitor heavy chains (HCs) has been reported to be linked to hyaluronan, which play important roles in tumour progression and metastasis. In this study, clinical significance of HCs in patients with liposarcoma was investigated.

METHODS

HC expression was studied by immunohistochemistry on resected specimens of 33 liposarcoma patients and 10 lipoma patients. The expression of HC mRNA was analyzed by reverse transcription polymerase chain reaction (RT-PCR). Serum concentration of HC was determined with enzyme-linked immunosorbent assay (ELISA).

RESULTS

Prominent positive staining of HC was observed in extracellular matrix of pleomorphic and myxoid liposarcoma. In well-differentiated liposarcoma and lipoma, faint staining was seen with HC. No products of HC could be detected by RT-PCR. Serum concentration of HC was not up-regulated in any subtypes of liposarcoma. HC expression was not significantly correlated with tumour subtypes and prognosis.

CONCLUSION

HC was strongly accumulated in pleomorphic and myxoid liposarcoma, however, was not locally synthesized in liposarcoma. HC might play roles in stabilizing extracellular matrix, such as hyaluronan (HA), in liposarcoma.

CSF hypocretin levels in Guillain-Barre syndrome and other inflammatory neuropathies

CSF hypocretin-1 was measured in 28 Guillain-Barré syndrome (GBS), 12 Miller-Fisher syndrome, 12 chronic inflammatory demyelinating polyneuropathy (CIDP), and 48 control subjects. Seven GBS subjects had undetectably low hypocretin-1 levels (<100 pg/mL). Hypocretin-1 levels were moderately reduced in an additional 11 GBS, 5 Miller-Fisher syndrome, and 1 CIDP subject. Low levels in GBS occurred early in the disease and were associated with upper CNS level abnormalities.

Telomerase, p53 and PCNA activity in osteosarcoma

AIMS

The aim of this study was to investigate telomerase activity and to assess the correlation between telomerase activity, tumor proliferative activity and p53 overexpression in osteosarcoma tumor samples.

METHODS

Using a telomerase polymerase chain reaction-enzyme-linked immunoassay based on the telomeric repeat amplification protocol method, we examined telomerase activity in 26 primary osteosarcoma specimens. P53 overexpression was identified using immunohistochemical staining, and tumor proliferative activity was assessed by immunohistochemical staining of PCNA.

RESULTS

Telomerase activity was detected at a relatively low level in five of 26 osteosarcoma tissue specimens. P53 was detected in eight of 21 cases. There was no significant correlation between telomerase activity and p53 overexpression (p=0.325). There was a significant correlation between PCNA staining and telomerase activity (p=0.0075).

CONCLUSION

Difference between the telomerase activity and p53 overexpression in osteosarcoma suggests that p53 and telomerase may not cooperate in tumor proliferation. Correlation of telomerase activity to PCNA expression suggests that telomerase activity may also useful for evaluate proliferative activity in osteosarcoma.

Stimulated type I collagen turnover in patients with giant cell tumor of bone

The aim of this study was to determine type I collagen turnover in giant cell tumor of bone (GCT) by biochemical markers of type I procollagen aminoterminal propeptide (PINP) and type I collagen carboxyterminal telopeptide (ICTP) as synthesis and degradation markers, respectively. The serum concentrations of PINP and ICTP were measured in 11 patients with GCT using radioimmunoassay, and analyzed by the correlation to the grades of GCT progression described by Campanacci. Serum of the 11 healthy subjects was available for comparison. The serum concentration of PINP was significantly higher in patients with GCT (82.4 +/- 46.2 ng/ml) than in controls (40.8 +/- 12.1 ng/ml) (P < 0.01), and that of ICTP was also significantly higher in GCT (5.3 +/- 2.0 ng/ml) than in controls (3.2 +/- 0.8 ng/ml) (P < 0.01). In GCT, the PINP concentration of grade 3 (127.6 +/- 38.8 ng/ml) was higher than that in grade 1 patients (46.9 +/- 4.8 ng/ ml) (P < 0.01). ICTP concentration of both grades 2 (7.1 +/- 1.4 ng/ml) and 3 (5.8 +/- 1.8 ng/ml) patients was significantly higher than that of grade 1 (3.5 +/- 0.6 ng/ ml) patients (P < 0.01, P < 0.05, respectively). Two cases of serum concentration of PINP and ICTP after resection of GCT demonstrated that these biomarkers decreased to the control levels in the absence of GCT. Our results indicated that type I collagen turnover evaluated by ICTP and PINP was stimulated in the presence of GCT. Moreover, this enhanced metabolic turnover reflects the grade of GCT.

Investigation of interfacial interaction between uncoated and coated carbon fibres and the magnesium alloy AZ91

Unidirectionally reinforced metal-matrix composites with a fibre volume content between 63 and 68% were processed by squeeze casting using T800 H carbon fibres and the magnesium alloy AZ91. The surface of the fibres was prepared by thermal desizing of the fibres or by deposition of a pyrolytic carbon (pyC) coating. Different interfacial conditions could be identified by transmission electron microscopy (TEM) and the single-fibre push-in test. TEM confirmed the formation of needle-like phases at the fibre surface or, for coated fibres, within the pyrolytic carbon coating. During loading by the Vickers type indenter an intense response was observed for composites of coated fibres and the magnesium alloy. This could by caused by stick-slip effects within the pyrolytic carbon coating.

Experimental observation of radiation from cherenkov wakes in a magnetized plasma

A proof-of-principle experiment demonstrates the generation of radiation from the Cherenkov wake excited by an ultrashort- and ultrahigh-power pulse laser in a perpendicularly magnetized plasma. The frequency of the radiation is in the millimeter range (up to 200 GHz). The intensity of the radiation is proportional to the magnetic field intensity as expected by theory. Polarization of the emitted radiation is also detected. The difference in the frequency of the emitted radiation between these experiments and previous theory can be explained by the electrons' oscillation in the electric field of a narrow column of ions in the focal region.

Interaction of an electromagnetic wave with a suddenly stopped ionization front

The theory of the interaction of an electromagnetic wave with a uniformly moving ionization front in a gas is extended to include the case when the front suddenly stops. This nonstationary character of the wave/front interaction, which is typical for experiments carried out in a finite-size gas tube, gives rise to fresh physical effects. First, currents induced near the plasma boundary after the front stops produce a static magnetic field not only in the plasma behind the front but also in the vacuum ahead of the front. Second, in the regime where the transmitted wave falls off behind the front, the skinning field leaks through the stopped front and produces a burst of highly frequency up-shifted radiation.

Propagation of short intense laser pulses in gas-filled capillaries

The guided laser pulse propagation and wake-field generation are studied in a wide (in comparison with the laser spot size) gas-filled capillary with an on-axis gas density depletion, which can be produced by a rapid spin of the capillary around its axis or by radially propagating shock waves generated in a piezoceramic tube. A single equation for the wake-field potential, which describes the fully relativistic plasma response in the presence of optical field ionization (OFI) of a gas, is derived and used to demonstrate a guided propagation of a short intense laser pulse over many Rayleigh lengths in a leaky plasma channel produced by the pulse due to OFI in the capillary filled with a radially inhomogeneous gas. The efficient generation of a regular wake field over long distances suitable for the laser wake-field accelerators is shown.