Makoto Yamada

• Osaka Metropolitan University

Vertebroplasty has shown excellent analgesic effects in patients with osteoporotic vertebral fractures. In Japan, percutaneous vertebroplasty, balloon kyphoplasty, and vertebral body stenting are commonly performed. All of these techniques require precise transpedicular vertebral puncture and complete cement filling without leakage. Puncture should...

A 74-year-old woman had a lacunar infarction in the brainstem and was admitted to Takeda General Hospital for treatment. She had significant sequelae and was discharged with a Modified Rankin Scale 0. Imaging follow-up was conducted every year after discharge on an outpatient basis. Seven years later, MRI of the head revealed a previous cerebral he...

Endoscopes with small diameters are widely desired in medical and industrial fields. In this study, we experimentally demonstrated single-pixel imaging (SPI) using a polarization-maintaining (PM) fiber array with few cores to achieve endoscope size reduction. We designed a PM-fiber array with four fibers for the SPI system. The fiber array generate...

A model describing the dynamic behavior of a few-mode erbium-doped fiber amplifier (FM-EDFA) is derived using the average inversion level. In that model, when the amplification overlap factor and equivalent area are independent of time, the dynamic behavior of an FM-EDFA is described by a differential equation of the average inversion level. This c...

We propose a network management method using a novel adapter that translates OpenFlow-based commands and vendor-specific commands using a single-board computer to achieve a low-cost centralized management of heterogeneous network devices including various vendors. The adapter is implemented in wired and wireless network devices and its operation is...

Single-pixel imaging (SPI) has recently drawn considerable attention as a new imaging technique. An SPI system using a multi-core fiber (MCF-SPI system) that we proposed for the first time has the potential to make the system very compact. This study is concerned with the features and reconstruction properties of MCF-SPI system. In this system, the...

It is important to reduce the cost of the sensing system to promote the social implementation of optical fiber sensors. The light source and the photodetector with analysis functions, e.g., optical spectrum analyzer, are the most expensive components of an optical fiber sensing system. To solve this problem, we have proposed an Ethernet-based tempe...

The sensitivity of a long-period fiber grating (LPFG) temperature sensor can be improved by 1.8 times by placing silicon oil with a high thermo-optical coefficient around the LPFG formed on the fiber.

This chapter provides a comprehensive review of the optical amplification technologies for space division multiplexing (SDM) transmission that has been studied extensively. It consists of the motivation, history, targets, categories, evaluation methods, and ongoing issues of SDM amplifiers. The amplification technologies discussed in this chapter a...

Fiber fuse, a thermal destruction phenomenon, which propagates toward optical sources and permanently damages optical fiber cores, connection points (connectors and splicing) as well as optical components sets the ultimate input optical power limits into optical fibers, thus determining the ultimate data capacity in optical fiber communication syst...

Fringe projection profilometry is a high-precision method used to measure the 3D shape of an object by projecting sinusoidal fringes onto an object. However, fringes projected onto a metallic or shiny object are distorted nonlinearly, which causes significant measurement errors. A high-precision measurement method for shiny objects that employs com...

Fringe projection profilometry (FPP) is a technique used for obtaining the three-dimensional shape of an object in fields such as reverse engineering, cultural heritage, and computer vision. The FPP measurement accuracy significantly depends on the arrangement of the measurement system, measurement space conditions, equipment setting, and object ch...

We have proposed a broadband hybrid light source that combines a super luminescent diode (SLD) and thulium-doped fiber amplifier (TDFA) and operates in the 1.8 µm band. This light source can improve the characteristics of the output spectrum by amplifying the output light of the SLD with TDFA. In this study, we investigate the dependence of the out...

The power consumption of optical repeater subsystems in a multicore fiber (MCF) link is analyzed via the simulation of an erbium-doped fiber amplifier (EDFA) considering the power consumption of an ancillary function and an EDFA. Ancillary power consumption is attributed to nonessential functions that are required only for the subsystem to operate....

This letter reports a proof‐of‐concept experiment conducted on a novel application of the multi‐core fibre (MCF), where image reconstruction is based on a single‐pixel imaging (SPI) technique and the diffraction pattern emitted from an MCF. The technique is intended to reduce the size of the SPI system, the applications of which can now be extended...

We propose a cost-effective method for temperature measurement range changing of the Ethernet-based optical fiber sensing system, and also show experimental results about the temperature measurement range changeability with a variable optical attenuator.

Objective: Few studies have examined the underlying cause of Adjacent segment disease (ASD) after decompression surgery for LSS. The goal of this study is to investigate factors related to the onset of ASD after decompression surgery based on the imaging results. Methods: We examined 95 patients who underwent single-level decompression for LSS (...

BACKGROUND Carotid free-floating thrombus (CFFT) is defined as a blood clot attached to the arterial wall with surrounding blood flow at its distal component. Although rare, it is a clinically significant cause of embolic stroke. CFTT within a stent has not been previously reported. CASE DESCRIPTION We report a 64-year-old man who underwent caroti...

Lumbar foraminal schwannomas occasionally present as giant lesions in the retroperitoneal cavity. Here, we report a case of a L5 giant foraminal schwannoma that was laparoscopically excised. A 26-year-old man visited our hospital with the complaint of numbness of the left leg that had persisted for 2 years. Magnetic resonance imaging scans revealed...

A new implementation of the weight vector in a classifier based on an optical system using a volume holographic filter with a vector decomposition algorithm is proposed for high‐speed data classification. Using a volume holographic filter, the correlation between the input and the decomposed weight vector is calculated for the classification score,...

Both lumbar canal stenosis (LCS) and peripheral arterial disease (PAD) can cause groin pain. Although differentiating the two pathologies is essential, it can be more challenging in patients with groin pain. We report the case of a 71-year-old woman with PAD who presented with left groin pain after surgery for LCS at L4/5. Before the surgery, she h...

A single-pixel imaging (SPI) system using a multi-core fiber (MCF), which is referred to as MCF-SPI, is proposed. It combines the MCF technology and SPI algorithm. A preliminary experiment of the spatial pattern generation was demonstrated using an MCF.

We simulated the differential modal gain (DMG) property of WDM amplification characteristics for a ring‐core erbium‐doped fibre (RC‐EDF) to clarify the possibility of an RC‐EDF being used as a three‐ to five‐signal LP‐mode amplification medium. The authors defined two parameters, DMGYY–XX and WDGXX. The former and the latter are the difference betw...

Background: Intracranial de novo arachnoid cysts in adults are rare, suggesting the involvement of head trauma and inflammatory diseases. We report a symptomatic adult case of nontraumatic de novo arachnoid cyst on the ventral medulla oblongata. Case description: A 56-year-old man came to our hospital complaining of dysphagia and writing difficu...

The importance of encryption in free‐space optical communication systems has been increasing due to their widespread use. Herein, for the first time, the authors propose a novel two‐dimensional encryption system for free‐space optical communication using two spatial patterns as encryption keys. A data stream is physically encrypted with optical sig...

This paper investigates gain controllability of cladding- and core-pumping hybrid-pumped single-stage and double-stage multi-core (MC) erbium-doped amplifiers (EDFAs) for changes in the input signal power per channel and number of channels. During the gain control, the core-pumping power is adjusted, while the cladding-pumping power is kept constan...

Optical fiber sensors have numerous advantages over electrical sensors. However, in some cases, sensing systems based on optical fiber sensors are inferior to electrical sensors in terms of cost because expensive instruments are required. Therefore, cost-effective options must be developed. Here, inexpensive optical transceivers (OTRs) for Ethernet...

The authors realised the first E-band thulium-doped fibre (TDF) amplifier, which includes a three-stage configuration fluoride-based TDF and two filters suppressing amplified spontaneous emission in the S-band.

This study aims to propose a method for adjusting loss peak in the spectrum of long period fiber grating fabricated with CO2 laser by applying tension with some weight to make the loss peak suitable for a multi-point temperature sensor under a high temperature environment. This method could achieve an increase of 5.3 dB in the value of loss peak by...

Spinal dural arteriovenous fistulas (SDAVF) develop by direct abnormal arteriovenous connection between both sides of the spinal dura matter. In this condition, there is no intervening nidus between a meningeal segmental artery and a radiculomedullary vein. Open microsurgery is one of the choices for patients with SDAVF. When the AVF is on the inne...

The incidence of cervical spine injuries (CSIs) among elderly patients is increasing in an aging society. An accurate diagnosis in the acute phase is important to avoid adverse clinical and sociolegal consequences. We present case reports of 2 elderly women who presented with cardiopulmonary arrest (CPA) with a delayed diagnosis of CSI. They presen...

Although computed tomographic angiography (CTA) is often the only modality for imaging before surgical treatment of intracranial aneurysms, it has some limitations and pitfalls. We report a case of diffuse subarachnoid hemorrhage (SAH) in which CTA revealed a small enhanced saccular abnormality on the surface of the caudal loop of the left posterio...

Lately, in order to tackle the surge in information and communication traffic, various researches and developments have been conducted to expand the communication channel capacity and ensure its effective distribution in communication network. We proposed the AWG-STAR network with loopback function to meet such capacity requirements for relatively...

This paper investigates the applicability of a model of a cladding-pumped multicore erbium-doped fiber amplifier (CP-MC-EDFA) that employs the average inversion level of an erbium ion. The model is modified to include the effects of multiple cores for modifications of the background loss coefficient of the pump light. The model is validated experim...

We simulated an improvement in fiber characteristics, specifically the differential modal gain (DMG) and the LP 11 mode wavelength dependent gain (WDG) characteristics. We defined the DMG as the gain difference between the C-band wavelength-division multiplexing signal channels of the LP 01 and LP 11 modes at the shortest wavelength, and WDG was th...

In this letter, we demonstrate a seven-core few-mode erbium-doped fiber amplifier by core pumping for long-haul transmission system using a few-mode multicore fiber. The differential modal gain between the LP01 and LP11 modes is reduced to 3.2 dB or less regardless of the pumping-light mode using a ring-core refractive-index profile, and flattened...

Given that the number of devices with Internet access continues to rapidly increase, vie see Internet traffic also steadily increasing. To accommodate such increases in Internet traffic, various technologies for realizing an expansion of communication capacity and efficiently consuming this capacity are actively being studied. One such technology f...

The effect of reducing the pump power in a multi-core erbium-doped fiber amplifier (MC-EDFA) designed for a wavelength-division-multiplexing (WDM)-interleaved multicore/ multi-fiber (MCF/MF) system is investigated. An analysis of the asymptotic behavior of the pump power ratio of the MCEDFA and discrete single-core EDFAs (SC-EDFAs), derived by usin...

Arrayed waveguide grating (AWG) has developed optical fiber communication networks in order to satisfy rapidly increasing traffic demands. We showed novel AWG-STAR network which had a function of dynamic wavelength path relocation using only some optical switches deployed in communication node without improving AWGs itself in previous studies. In t...

Purpose The purpose of this study was to evaluate total spinal alignment in asymptomatic individuals with 6 lumbar vertebrae (LVs). Methods The present study comprised 167 Japanese adult volunteers with no spinal symptoms. In all individuals, standing radiographs of the entire spine were taken to measure the pelvic incidence (PI), sacral slope (SS)...

In this paper, we present long-haul 32-core dense space division multiplexed (DSDM) unidirectional transmission over a single-mode multicore transmission line. We developed a low-crosstalk heterogeneous 32-core fiber with a square lattice arrangement, and a novel partial recirculating loop system. The span crosstalk of the 51.4-km 32-core transmiss...

We propose a new crosstalk measurement method for multi-core fiber fan-in/fan-out devices utilizing the Fresnel reflection. Compared with the traditional method using core-to-core coupling between a multi-core fiber and a single-mode fiber, the proposed method has the advantages of high reliability and much shorter measurement time. Statistical pro...

We demonstrate 32-core dense space-division multiplexed (DSDM) unidirectional transmission of PDM-16QAM 20-WDM signals over 1644.8km employing a low-crosstalk single-mode heterogeneous 32-core fiber in a partial recirculating-loop system.

This study reports on a case that forces re-examination of merits and demerits of anterior cervical fusion. A 79-year-old male was brought to the emergency room (ER) of our hospital after he fell and struck the occipital region of his head following excessive alcohol consumption. Four years prior, he had undergone anterior cervical discectomy and f...

Research related to increasing network capacity and developing a network control function in Local Area Networks (LAN) has employed Wavelength Division Multiplexing (WDM) to handle the rapid increase in network traffic. An Arrayed Waveguide Grating (AWG)-STAR network with looping back has a function that can dynamically and flexibly rearrange a ful...

Effective supporting environment has been investigated and evaluated for students to improve their decision-making skills in problem-based learning. The supporting environment consists of systematic information given to students as hints by the problem itself, available materials they can use in their trials and the information on supporting system...

A fiber amplifier supporting 2 LP modes that employs a ring-core erbium-doped fiber (RC-EDF) is investigated to reduce differential modal gain (DMG). The inner and outer radii of the ring-core of the RC-EDF are clarified for 2-LP mode operation of the amplifier, and are optimized to reduce the DMG. It is shown that using the overlap integral betwee...

The point-to-point (P2P) and one-by-one (O-O) optical wavelength paths were investigated in IP (Internet Protocol)/Ethernet over AWG (Arrayed Waveguide Grating)-STAR network to reveal the reconfigurability and scalability for customer-owned optical network application. An IP-routing control system was designed and implemented to manage optical wave...

A 63-year-old male suffered from right hypertensive putaminal hemorrhage and was admitted to hospital. Although his left paresis was improved by conservative treatment, cerebral angiography demonstrated a rare case of unruptured anterior communicating artery aneurysm associated with agenesis of left internal carotid artery (ICA). 3DCT revealed abse...

A widely tunable Raman laser covering a 170-nm bandwidth was demonstrated using a single-mode tellurite fiber embedded in a ring cavity.

We propose a novel IP over AWG-STAR network with dynamically relocatable wavelength paths via communication node-side control. Experimental results demonstrate that the transmission capacity between communication nodes can be dynamically increased from 1 Gbps to 3 Gbps via adding looped-back wavelength paths to the internode in the proposed IP over...

We demonstrate the unrepeatered transmission of over 100 Tb/s by employing a multicore-fiber-based remote optically pumped amplifier. We establish 120.7-Tb/s, 204-km seven-core fiber transmission with the aggregate spectral efficiency (SE) of 53.6 b/s/Hz, a record capacity per fiber and the highest SE for unrepeatered transmission. We also realized...

We propose long-haul space-division-multiplexing (SDM) transmission systems employing parallel multiple-input multiple-output (MIMO) frequency-domain equalization (FDE) and transmission fiber with low differential mode delay (DMD). We first discuss the advantages of parallel MIMO FDE technique in long-haul SDM transmission systems in terms of the c...

Unexpected bleeding from the dural sinus can sometimes occur when performing a dural opening during microvascular decompression. We conducted dural opening safely by performing indocyanine green (ICG) videoangiography before making a dural incision. We introduce two specific cases in which surgery was performed to treat a trigeminal neuralgia. In b...

The differential modal gain (DMG) in a few-mode erbium-doped fibre amplifier (FM-EDFA) is successfully improved by employing a ring-core FM erbium-doped fibre (RC-EDF). The DMGs between LP01 and LP11 mode signals in the FM-EDFA with the RC-EDF are 1.8 and 1.6 dB for LP01 and LP11 mode pumping, respectively, whereas those in a FM-EDFA with a convent...

Aim: The efficacy of vertebroplasty on acute vertebral compression fractures (VCFs) has not yet been established. This study, focusing on patients with acute VCFs, aims to compare therapeutic effects between vertebroplasty and vertebral perforation without cement injection. Material and methods: Fifty-five patients with single painful VCFs were...

A new 1.8 μm broadband light source for measuring concentrations of organic solutes is developed by combining an amplified sponteneous emission (ASE) light source that uses a Tm3+-Tb3+-doped fiber and commercially available light sources. The ASE intensity exceeded -50 dBm/nm for a bandwidth of ∼1520 to ∼1850 nm. We constructed a near-IR spectrosco...

Pelvic insufficiency fractures (PIFs) are atraumatic fragility fractures due to osteoporosis. PIFs can be a source of lower back pain and referred symptoms in the buttocks, legs, and groin ; however, they are often unsuspected and overlooked in the clinically because of a low suspicion and the poor sensitivity of radiography. We report two cases of...

A local accumulation and trigger scheme has been proposed to collect small data efficiently. The system was implemented, based on the proposed scheme, and the functions were examined over an optical IP network. The results clarified that the system accumulated small data, and sent them to a center successfully. It has been shown that the total amou...

Coarse wavelength division multiplexing (CWDM) network has proven to be promising lower cost network architecture for a significant cost advantage over dense wavelength division multiplexing due to the lower cost of lasers and the filters used in CWDM modules. A compatible amplifier module having bidirectional amplification capability was deployed...

The influence of vertebral cement augmentation on spinal sagittal balance is unknown. The present study aimed to analyze the changes in total spinal alignment after Kyphoplasty in VCF patients. The study involved 21 VCF patients who underwent Kyphoplasty. In all patients, lateral radiographs of the entire spine were taken preoperatively and 1 month...

The first light source with a broadband spectrum in the 1800 nm wavelength region has been developed by employing a cascade configuration with a 1.65 μm band super luminescent diode and a Tm3+-doped fibre amplification unit. The achieved bandwidth where the intensity exceeded -20 dBm/nm was 247 nm (from 1611 to 1858 nm) with a low ripple, whose pea...

An inter-core crosstalk measurement method in a multi-core erbium-doped fibre amplifier that uses a single-wavelength signal with multiple intensity tones is investigated. Its feasibility is confirmed and the output signal power dependence of the crosstalk values for the same signal gains between cores is successfully characterised.

Amplification technologies are categorized for a multi-core erbium-doped fiber amplifier (MC-EDFA) including a pump scheme and an active fiber. MC-EDFAs are described that employ discretely pumped single-cladding MC-EDF and cladding-pumped double-cladding MC-EDF.

Over the past 20 years, vertebroplasty has become a widely adopted treatment for vertebral compression fractures unresponsive to traditional conservative treatment. Although vertebroplasty might provide immediate pain relief and improved function in patients with vertebral compression fracture, patient selection is the most critical factor in predi...

The method for estimating the gain coefficient spectrum of an erbium-doped fiber (EDF) is proposed and demonstrated experimentally. The method employs a net gain–loss measurement that uses the I 4 13 / 2 level pumping of the EDF and the McCumber relation. A formula used to obtain the quotient of the gain and loss coefficient from the net gain–loss...

We realize for the first time a 1.7 μm band fiber amplifier. The maximum gain of 22.5 dB and the noise figure of 6.2 dB were achieved at the signal wavelength of 1700 nm.

We report the first experimental realization of a 1.7 μm band optical fiber amplifier by using a Tm3+-Tb3+-doped fiber as an active fiber, and 1.21μm LD pumping. The maximum signal gain of 22.5 dB and a 3 dB down output signal power of -1 dBm have been achieved at the signal wavelength around 1700 nm with a launched pump power of 277 mW. The 3 dB d...

We propose a novel AWG-star network with dynamically reconfigurable wavelength paths via node-side control. We demonstrate that transmission capacity between the communication nodes can be increased dynamically by adding loop-backed wavelength paths.

A multicore Er3+-doped fiber amplifier (MC-EDFA) can be realized by using an amplification medium such as bundled or multi-element Er3+-doped fiber (EDF) and multicore EDF, and employing a discrete pumping or cladding pumping method. In this paper, we report three recently developed MC-EDFAs, which represent all the amplification forms realizable u...

The first tunable fibre ring laser in the 1700 nm wavelength region has been developed. To achieve this fibre laser, a Tm3+-Tb3+-doped fibre is used as the active fibre, along with a tunable bandpass filter. A fibre ring laser that consisted of a 1.2/1.7 μm band wavelength division multiplexing coupler, a tunable bandpass filter, an active fibre an...

Ten resonant wavelengths could be multiplexed successfully by writing long-period gratings (LPGs) with different pitches using a CO2 laser. A preliminary distributed temperature monitoring experiment was conducted, and it was estimated that separation between 2 adjacent resonant peaks was 13.2 nm, even when the temperature difference between 2 adja...

The postoperative time course of redundant nerve roots (RNRs) in patients with lumbar spinal canal stenosis (LSCS) is currently unknown. The purpose of this study is to investigate the relationship between postoperative morphological changes in detected RNRs and clinical outcome of patients with LSCS. 33 symptomatic LSCS patients who demonstrated R...

Bidirectional stackable ROADMs (BS-ROADMs) with 3-port optical add/drop multiplexers (OADMs) have been presented for minimizing the lightpath interference during reconfiguration of the ROADMs. The BS-ROADM is constructed by connecting some modules with different wavelengths, and it is reconfigured by adding new modules required in it. The reconfigu...

Stackable reconfigurable optical add–drop multiplexers (S-ROADMs) have been proposed for single-fiber coarse wavelength division multiplexing (CWDM) ring networks so as to perform lightpath reconfiguration remotely. The S-ROADM consists of some modules with different wavelengths required in the node, and with this facility manual ROADM reconfigurat...

We demonstrate bidirectional transmission over 450 km of newly-developed dual-ring structured 12-core fiber with large effective area and low crosstalk. Inter-core crosstalk is suppressed by employing propagation-direction interleaving, and 409-Tb/s capacities are achieved for both directions.

We have experimentally clarified the optical amplification characteristics of a remotely pumped multicore erbium-doped fiber amplifier system. The pumping efficiencies of the system are ~4 times higher than those of the distributed Raman amplification system.

Surgical resection of cerebral arteriovenous malformations (AVMs) is a certain but difficult treatment because of its complicated pathology and the sometimes limited experience of the neurosurgeon. Therefore, care in deciding the surgical indication and strategy is essential. We report three cases of AVMs from the viewpoint of an inexperienced neur...

We show, for the first time, simple formulas that describe the crosstalk characteristics of a multi-core optical fiber amplifier. The influences of the gain difference and the fan-in/out devices on the crosstalk measurement are discussed.

Percutaneous vertebral body perforation is a new technique for treating painful vertebral compression fractures (VCFs). We prospectively evaluated this treatment in 45 consecutive patients with 63 VCFs treated at our hospital between September and December 2009. In all patients, long-term conservative treatment had failed to achieve pain relief, re...