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Decompression surgery is the most common surgical treatment for lumbar spinal stenosis (LSS). Relatively low satisfaction rate was reported. Patients often complaint of residual numbness despite significant pain relief. We hypothesized that numbness had a significant impact on patient satisfaction, but had not been evaluated, which is associated with low satisfaction rate. This study aimed to examine how much numbness is associated with patient satisfaction. We retrospectively reviewed prospectively collected data from consecutive patients who underwent decompression without fusion for LSS. We evaluated the Numeric Rating Scale (NRS) scores of low back pain (LBP), leg pain, and leg numbness preoperatively and at the final follow-up visit. Improvement was evaluated using minimum clinically important differences (MCIDs). Patient satisfaction was evaluated using the question, "How satisfied are you with the overall result of your back operation?". There are four possible answers consisting of "very satisfied (4-point)", "somewhat satisfied (3-point)", "somewhat dissatisfied (2-point)", or "very dissatisfied (1-point)". Spearman correlation was used to evaluate the association between patient satisfaction and reaching MCIDs. A total of 116 patients were included. All three components had correlation with patient satisfaction with the correlation efficient of 0.30 in LBP, 0.22 in leg pain, and 0.33 in numbness. Numbness had greatest correlation efficient value. We showed that numbness has a greater impact than leg/back pain on patient satisfaction in patients undergoing decompression for LSS. We suggest not only LBP and leg pain but also numbness should be evaluated pre- and postoperatively.

Adolescent idiopathic scoliosis (AIS) is a common disease causing three-dimensional spinal deformity in as many as 3% of adolescents. Development of a method that can accurately predict the onset and progression of AIS is an immediate need for clinical practice. Because the heritability of AIS is estimated as high as 87.5% in twin studies, prediction of its onset and progression based on genetic data is a promising option. We show the usefulness of polygenic risk score (PRS) for the prediction of onset and progression of AIS. We used AIS genomewide association study (GWAS) data comprising 79,211 subjects in three cohorts and constructed a PRS based on association statistics in a discovery set including 31,999 female subjects. After calibration using a validation data set, we applied the PRS to a test data set. By integrating functional annotations showing heritability enrichment in the selection of variants, the PRS demonstrated an association with AIS susceptibility (p = 3.5 × 10-40 with area under the receiver-operating characteristic [AUROC] = 0.674, sensitivity = 0.644, and specificity = 0.622). The decile with the highest PRS showed an odds ratio of as high as 3.36 (p = 1.4 × 10-10 ) to develop AIS compared with the fifth in decile. The addition of a predictive model with only a single clinical parameter (body mass index) improved predictive ability for development of AIS (AUROC = 0.722, net reclassification improvement [NRI] 0.505 ± 0.054, p = 1.6 × 10-8 ), potentiating clinical use of the prediction model. Furthermore, we found the Cobb angle (CA), the severity measurement of AIS, to be a polygenic trait that showed a significant genetic correlation with AIS susceptibility (rg = 0.6, p = 3.0 × 10-4 ). The AIS PRS demonstrated a significant association with CA. These results indicate a shared polygenic architecture between onset and progression of AIS and the potential usefulness of PRS in clinical settings as a predictor to promote early intervention of AIS and avoid invasive surgery. © 2021 American Society for Bone and Mineral Research (ASBMR).

To characterize clinically measurable endophenotypes, implicating the TBX6 compound inheritance model. Patients with congenital scoliosis (CS) from China(N = 345, cohort 1), Japan (N = 142, cohort 2), and the United States (N = 10, cohort 3) were studied. Clinically measurable endophenotypes were compared according to the TBX6 genotypes. A mouse model for Tbx6 compound inheritance (N = 52) was investigated by micro computed tomography (micro-CT). A clinical diagnostic algorithm (TACScore) was developed to assist in clinical recognition of TBX6-associated CS (TACS). In cohort 1, TACS patients (N = 33) were significantly younger at onset than the remaining CS patients (P = 0.02), presented with one or more hemivertebrae/butterfly vertebrae (P = 4.9 × 10‒8), and exhibited vertebral malformations involving the lower part of the spine (T8–S5, P = 4.4 × 10‒3); observations were confirmed in two replication cohorts. Simple rib anomalies were prevalent in TACS patients (P = 3.1 × 10‒7), while intraspinal anomalies were uncommon (P = 7.0 × 10‒7). A clinically usable TACScore was developed with an area under the curve (AUC) of 0.9 (P = 1.6 × 10‒15). A Tbx6-/mh (mild-hypomorphic) mouse model supported that a gene dosage effect underlies the TACS phenotype. TACS is a clinically distinguishable entity with consistent clinically measurable endophenotypes. The type and distribution of vertebral column abnormalities in TBX6/Tbx6 compound inheritance implicate subtle perturbations in gene dosage as a cause of spine developmental birth defects responsible for about 10% of CS.

Background Congenital scoliosis (CS) is defined as a lateral curvature of the spine due to the vertebral malformations and has an incidence of 0.5–1/1,000 births. We previously examined TBX6 in Japanese CS patients and revealed that approximately 10% of CS was caused by TBX6 mutations. However, the genetic cause of remaining CS is unknown. Methods We recruited 78 CS patients without TBX6 mutations and major comorbidities, and investigated the genes previously reported to be associated with CS and congenital vertebral malformations by whole‐exome sequencing. Results We identified the compound heterozygous missense variants in LFNG in one patient. No likely disease‐causing variants were identified in other patients, however. LFNG encodes a GlcNAc‐transferase. The LFNG variants showed loss of their enzyme function. Conclusions A LFNG mutation is reported in a case of spondylocostal dysostosis (SCD), a skeletal dysplasia with severe malformations of vertebra and rib. The CS patient with LFNG mutations had multiple vertebral malformations including hemivertebrae, butterfly vertebrae, and block vertebrae, and rib malformations. LFNG mutations may cause a spectrum of phenotypes including CS and SCD. The current list of known disease genes could explain only a small fraction of genetic cause of CS.

Genetic case-control study of single nucleotide polymorphisms (SNPs).To examine the association of previously reported susceptibility genes for adolescent idiopathic scoliosis (AIS) and intervertebral disc (IVD) degeneration with adult spinal deformity (ASD).ASD is a spinal deformity that develops and progresses with age. Its etiology is unclear. Several ASD susceptibility genes were recently reported using a candidate gene approach; however, the sample sizes were small and associations with ASD development were not determined.ASD was defined as structural scoliosis with a Cobb angle more than 15° on standing radiographs, taken of patients at age 40 to 75 years in this study. Subjects in whom scoliosis was diagnosed before age 20 were excluded. We recruited 356 Japanese ASD subjects and 3341 healthy controls for case-control association studies of previously reported SNPs. We genotyped four known AIS-associated SNPs (rs11190870 in LBX1, rs6570507 in GPR126, rs10738445 in BNC2, and rs6137473 in PAX1) and three IVD degeneration-associated SNPs (rs1245582 in CHST3, rs2073711 in CILP, and rs1676486 in COL11A1) by the Invader assay.Among the AIS-associated SNPs, rs11190870 and rs6137473 showed strong and nominal associations with ASD (P = 1.44 × 10, 1.00 × 10, respectively). Of the IVD degeneration-associated SNPs, rs1245582 and rs2073711 showed no association with ASD, while rs1676486 showed a nominal association (P = 1.10 × 10). In a subgroup analysis, rs11190870 was significantly associated with a Cobb angle more than 20° in the minor thoracic curve (P = 1.44 × 10) and with a left convex lumbar curve (P = 6.70 × 10), and nominally associated with an apical vertebra higher than L1 (P = 1.80 × 10).rs11190870 in LBX1, a strong susceptibility SNP for AIS, may also be a susceptibility SNP for ASD. Thus, ASD and AIS may share a common genetic background.4.

Fipronil is a phenylpyrazole insecticide that is widely used as a pesticide and a veterinary drug, although studies suggest that it could be toxic to mammals. The objectives of this study were to examine the pharmacokinetic profile of fipronil in mice, dogs, and cats, and to evaluate its effects on emotional and cognitive behaviors of dogs and cats using the data obtained from mice. The assessment of in vivo kinetics of fipronil was conducted in mice and dogs. We also performed behavioral tests (elevated plus-maze and Y-maze) and measured the levels of neurotransmitters in mice exposed to fipronil. In addition, the in vitro metabolism of fipronil were evaluated using liver microsomes of rats, mice, dogs, and cats. The results revealed that fipronil is distributed throughout the body (blood, brain, adipose tissue, and liver) of mice after dermal application. It was metabolized to fipronil sulfone primarily in the liver. The data on kinetics show that both fipronil and fipronil sulfone have a longer half-life in dogs and cats than in mice. The behavioral tests indicated that fipronil and fipronil sulfone could affect emotional and cognitive behaviors and alter the levels of neurotransmitters (dopamine in the striatum and serotonin in the hippocampus) in mice. Furthermore, we found that dogs and cats have a low ability to metabolize fipronil than mice and rats. However, further comprehensive studies are needed to determine whether fipronil affects the emotional and cognitive behaviors when administered to dogs and cats. To the best of our knowledge, this is the first study to examine the pharmacokinetic data and verify the effects of fipronil on emotional and cognitive behaviors of dogs and cats using the data obtained from mice.

Adolescent idiopathic scoliosis (AIS) is the most common type of scoliosis. Controlling its curve progression is the most important clinical task. Although recent genome-wide association studies (GWASs) identified several susceptibility loci associated with the development of AIS, the etiology of curve progression has been still unknown. Our previous GWAS has identified that rs12946942 showed significant association with severe AIS. To confirm the association, we conducted an international meta-analysis using four cohorts with different ethnicity. We analyzed 2272 severe AIS cases and 13,859 controls in total, and found the replication of significant association of rs12946942 (combined P = 7.23×10−13; odds ratio = 1.36, 95% confidence interval = 1.25−1.49). In silico analyses suggested that SOX9 is the most likely susceptibility gene for AIS curve progression in the locus.

Adolescent idiopathic scoliosis (AIS) is the most common type of spinal deformity and has a significant genetic background. Genome-wide association studies (GWASs) identified several susceptibility loci associated with AIS. Among them is a locus on chromosome 6q24.1 that we identified by a GWAS in a Japanese cohort. The locus is represented by rs6570507 located within GPR126. To ensure the association of rs6570507 with AIS, we conducted a meta-analysis using eight cohorts from East Asia, Northern Europe and USA. The analysis included a total of 6,873 cases and 38,916 controls and yielded significant association (combined P = 2.95 × 10−20; odds ratio = 1.22), providing convincing evidence of the worldwide association between rs6570507 and AIS susceptibility. In silico analyses strongly suggested that GPR126 is a susceptibility gene at this locus.

Adolescent idiopathic scoliosis (AIS) is a common spinal deformity with the prevalence of approximately 3%. We previously conducted a genome-wide association study (GWAS) using a Japanese cohort and identified a novel locus on chromosome 9p22.2. However, a replication study using multi-population cohorts has not been conducted. To confirm the association of 9p22.2 locus with AIS in multi-ethnic populations, we conducted international meta-analysis using eight cohorts. In total, we analyzed 8,756 cases and 27,822 controls. The analysis showed a convincing evidence of association between rs3904778 and AIS. Seven out of eight cohorts had significant P value, and remaining one cohort also had the same trend as the seven. The combined P was 3.28 × 10−18 (odds ratio = 1.19, 95% confidence interval = 1.14–1.24). In silico analyses suggested that BNC2 is the AIS susceptibility gene in this locus.

Congenital scoliosis (CS) is a congenital deformity of the spine, which can present as an isolated malformation, or part of a syndrome with other clinical features such as renal, cardiac, gastrointestinal, and limb malformations, etc. FGF, WNT, Notch, and TGFβ signaling pathway-associated genes have important roles in spine development. In this chapter, we highlight the embryologic basis of CS, including relevant genes associated with CS etiology. We review the genetic approaches used to understand molecular etiologies and pathogenic mechanisms for CS. Genes contributing to CS and associated vertebral malformation syndromes are also summarized.

Case-only study.The aim of this study was to confirm the association of rs11190870 with adolescent idiopathic scoliosis (AIS) severity in Japanese patients with AIS.Although the association of rs11190870 with AIS susceptibility is replicated in multiple ethnics, the association of rs11190870 with curve severity is controversial. Since the previous studies are of small, we performed a replication study using far larger number of patients than previous studies.A total of 1860 Japanese patients with AIS who had reached skeletal maturity or undergone surgical fusion were included in the study. We evaluated the association between rs11190870 and AIS progression for the entire group, and then for patients grouped according to a severe curve (a Cobb angle of ≥40°) or mild curve (a Cobb angle30°). Because braces could affect the results of the present study, patients in the mild-curve group were divided according to whether or not they had worn a brace. We then evaluated associations between rs11190870 genotype and curve severity in these groups.The mean Cobb angles were 54.8° ± 12.1° in the severe-curve group and 24.4° ± 4.0° in the mild-curve group. The difference in rs11190870 risk-allele frequency between the severe- and mild-curve groups was evaluated. No significant differences were observed. We then examined the association of rs11190870 risk-allele frequency between patients in the mild- and severe-curve groups using the χ test for three models, and found a marginal association between rs11190870 and curve severity in the dominant model (P = 0.035, odds ratio = 1.51).We found no association between rs11190870 and curve severity using the criteria of previous study. However, we found a marginal association between rs11190870 and curve severity. Large-scale replication studies that consider skeletal maturity and brace history, including replication studies in other ethnic groups, would be helpful for clarifying the association.4.

In this paper, we propose joint cooperative-transmit/receive frequency-domain equalization (cooperative-Tx/Rx FDE) with incremental relaying (IR) for broadband single-carrier (SC) transmission under the total and individual transmit power constraint at a source node (S) and a relay node (R). We derive the optimum cooperative-Tx/Rx FDE weights to minimize the mean square error (MSE) after packet combining at a destination node (\ssr D). We show that the optimum cooperative-Tx FDE weights allocate the transmit power in the minimum MSE (MMSE) sense in the frequency domain and in the maximal ratio transmission (MRT) sense in the spatial domain. To relax the condition that the complete channel state information (CSI) needs to be shared among all nodes, selection-based suboptimum cooperative-Tx FDE weights are derived. Computer simulation verifies the effectiveness of the proposed schemes and shows that the 5%-outage throughput of the system can be increased by around 30% over the conventional IR with only Rx FDE.

We built up a Long Term Evolution (LTE) trial system operating in 5.8 GHz unlicensed bands and conducted a real time field trial in typical indoor environments. The user throughput of LTE with the 20MHz carrier in the unlicensed bands, which is used as a Supplemental Downlink (SDL) (always downlink), is evaluated and compared with that of Wireless Local Area Network (WLAN) with the same bandwidth. Our test results show that LTE achieves better coverage and larger capacity in the 5.8 GHz unlicensed spectrum than WLAN alone. In addition, our test results on the intra-Radio-Access-Technology (RAT) coexistence performance conducted in different interference scenarios clarifies that an interference avoidance technology is necessary in LTE in unlicensed bands especially for dense deployment such as inter-operator coexistence case.

Many kinds of passive and active mixers have been studied using micromixing principles, and many of them mainly depend on molecular diffusion as the source of the mixing. Therefore, using a small diffusive distance is a primary method of improving in micromixing. The study of straight-flow micromixing utilizing a gas-liquid free interface in our laboratory confirmed that regional changes in flow direction near the bubble played a definitive role in rapid mixing. To achieve fast mixing using these two effects, we developed a new micromixing device that utilizes a thin liquid film between two static bubbles. The size of the bubbles was larger than that of the channel cross section in a Y-type straight-flow microchannel. In this study, we discuss the formation and behavior of bubbles or liquid films on the basis of the results of bubble forming experiments, as basic research toward developing the new device. We conducted the experiments using several test channels that had different sizes and locations of bubbles, and using CFD (computational fluid dynamics) simulation, we calculated the mixing performance in different designs of the mixing device. As a result, we successfully achieved the formation of static bubbles and thin liquid films under the condition of a low Reynolds number of 0.17. In addition to confirming that our new mixing device can be applied under that condition, we found that it has a stable capability for mixing.

Congenital scoliosis (CS) is a common vertebral malformation with incidence of up to 1 of 1000 births worldwide. Recently, TBX6 has been reported as the first disease gene for CS: about 10% of CS patients are compound heterozygotes of rare null mutations and a common haplotype composed by 3 SNPs in TBX6. Lefebvre et al in this journal reported that 2 patients with spondylocostal dysostosis (SCD), a rare skeletal dysplasia affecting spine and ribs also have TBX6 mutations: 1 carried the microdeletion and a rare missense variant, and another 2 rare missense variants. We investigated the pathogenicity of the 3 missense variants in SCD by a luciferase assay. The results were negative for the proposal of Lefebvre et al. We consider these 2 SCD patients are more probably compound heterozygotes of null mutations and a common risk haplotype just as CS patients with TBX6 mutations.

For the realization of future wireless networks, gigabit wireless technology, which can achieve higher-than-1 Gbps data transmission with extremely low transmit power, is indispensable. We have been studying the distributed antenna network (DAN) and the frequency domain wireless signal processing. In DAN, many antennas or clusters of antennas are spatially distributed over a service area, and they are connected by means of optical fiber links with DAN signal processing center. A number of distributed antennas cooperatively serve mobile users using spatial multiplexing, diversity, array, or relaying technique. In this paper, the recent advances in single-carrier DAN are introduced. Copyright © 2011 John Wiley & Sons, Ltd.

Frequency-domain equalization (FDE) based on minimum mean square error (MMSE) is considered as a promising equalization technique for a broadband single-carrier (SC) transmission. When a square-root Nyquist filter is used at a transmitter and receiver to limit the signal bandwidth, the presence of timing offset produces the inter-symbol interference (ISI) and degrades the bit error rate (BER) performance using MMSE-FDE. In this paper, we discuss the mechanism of the BER performance degradation in the presence of timing offset. Then, we propose joint MMSE-FDE & spectrum combining which can make use the excess bandwidth introduced by transmit filter to achieve larger frequency diversity gain while suppressing the negative effect of the timing offset.

In this paper, we propose a novel iterative transmit/receive equalization technique for single-carrier (SC) block transmission in a severe frequency-selective fading channel. Iterative frequency-domain inter-symbol interference (ISI) cancellation (FDIC) is introduced to the previously proposed joint iterative transmit/receive frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion. 1-tap FDE is employed at the transmitter. At the receiver, a 1-tap FDE and FDIC are jointly used and they are updated in an iterative manner. The transmit FDE weight is derived based on the MMSE criterion by taking into account the reduction of residual ISI in the receiver. To derive the weight, the transmitter assumes that the receiver can partially reduce the residual ISI after the FDIC. We conduct a computer simulation to investigate the achievable bit error rate (BER) performance to confirm the effectiveness of our proposed technique.

Recently, assuming ideal brick-wall transmit filtering, we proposed a frequency-domain block signal detection (FDBD) with maximum likelihood detection employing QR decomposition and M-algorithm (called QRM-MLD) for the reception of single-carrier (SC) signals transmitted over a frequency-selective fading channel. QR decomposition (QRD) is applied to a concatenation of the propagation channel and discrete Fourier transform (DFT). However, a large number of surviving paths is required in the M-algorithm to achieve sufficiently improved bit error rate (BER) performance. The introduction of filtering can achieve improved BER performance due to larger frequency diversity gain while keeping a lower peak-to-average power ratio (PAPR) than orthogonal frequency division multiplexing (OFDM). In this paper, we develop FDBD with QRM-MLD for filtered SC signal reception. QRD is applied to a concatenation of transmit filter, propagation channel, and DFT. We evaluate BER and throughput performances by computer simulation. From performance evaluation, we discuss how the filter roll-off factor affects the achievable BER and throughput performances and show that as the filter roll-off factor increases, the required number of surviving paths in the M-algorithm can be reduced.

Direct-sequence code division multiple access (DS-CDMA) is a promising uplink access technology for broadband cellular mobile communication systems. In this paper, we propose a joint transmit (Tx)/iterative receive (Rx) frequency-domain equalization (FDE) for DS-CDMA. In the proposed scheme, simple one-tap FDE at the transmitter and iterative one-tap FDE at the receiver are jointly performed using the common knowledge of channel state information (CSI). Before transmitting the signal, the transmitter predicts the degree of residual inter-chip interference (ICI) power after the iterations of Rx FDE to determine the Tx FDE weight while the receiver performs the iterative Rx FDE. In practice, it is almost impossible to share the perfect knowledge of CSI. In this paper, a Gaussian approximation of channel estimation (CE) errors is introduced. We theoretically derive a set of Tx and iterative Rx FDE weights based on the minimum mean square error (MMSE) criterion in the presence of the CE error. We show by computer simulation that the proposed scheme provides better bit error rate (BER) performance than the conventional scheme which uses iterative Rx FDE only (i.e., without Tx FDE) even in the presence of CE error. Copyright © 2010 John Wiley & Sons, Ltd.

SUMMARY Single-carrier (SC) multiple access is a promising uplink multiple access technique because of its low peak-to-average power ratio (PAPR) property and high frequency diversity gain that is achievable through simple one-tap frequency-domain equalization (FDE) in a strong frequency-selective channel. The multiple access capability can be obtained by combining either frequency division multiple access (FDMA) or code division multiple access (CDMA) with SC transmission. In this article, we review the recent research on the SC multiple access techniques with one-tap FDE. After introducing the principle of joint FDE/antenna diversity combining, we review various SC multiple access techniques with one-tap FDE, i.e., SC-FDMA, SC-CDMA, block spread CDMA, and

Frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion can provide a better bit error rate (BER) performance than rake combining. To further improve the BER performance, cyclic delay transmit diversity (CDTD) can be used. CDTD simultaneously transmits the same signal from different antennas after adding different cyclic delays to increase the number of equivalent propagation paths. Although a joint use of CDTD and MMSE-FDE for direct sequence code division multiple access (DS-CDMA) achieves larger frequency diversity gain, the BER performance improvement is limited by the residual inter-chip interference (ICI) after FDE. In this paper, we propose joint FDE and despreading for DS-CDMA using CDTD. Equalization and despreading are simultaneously performed in the frequency-domain to suppress the residual ICI after FDE. A theoretical conditional BER analysis is presented for the given channel condition. The BER analysis is confirmed by computer simulation.

Recently, frequency-domain equalization (FDE) has been attracting much attention as a way to improve single-carrier (SC) signal transmission in a frequency-selective wireless channel. Since the SC signal spectrum is spread over the entire signal bandwidth, FDE can take advantage of channel frequency-selectivity and achieve the frequency diversity gain. SC with FDE is a promising wireless signal transmission technique. In this article, we review the pioneering research done on SC with FDE. The principles of simple one-tap FDE, channel estimation, and residual inter-symbol interference (ISI) cancellation are presented. Multi-input/multi-output (MIMO) is an important technique to improve the transmission performance. Some of the studies on MIMO/SC with FDE are introduced.

In the next generation mobile communication systems, multiple-input multiple-output (MIMO) multiplexing is an indispensable technique to achieve very high-speed data transmission with a limited bandwidth. In MIMO multiplexing, it is necessary to estimate the channels between transmit and receive antennas for signal detection. In this paper, we propose a minimum mean square error (MMSE) channel estimation using cyclic delay pilot for single-carrier (SC)-MIMO multiplexing. In the proposed channel estimation, the same pilot block is altered through the addition of different cyclic delays and transmitted from different antennas at the same time for simultaneous estimation of all channels between transmit and receive antennas. We evaluate by computer simulation the bit error rate (BER) performance of MIMO multiplexing using the proposed channel estimation and compare it to those using time-multiplexed pilot based channel estimation (TMP-CE) and code-multiplexed pilot based channel estimation (CMP-CE).

The performance of single-carrier (SC) transmission in a frequency-selective fading channel degrades due to a severe inter-symbol interference (ISI). Using frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion can improve the bit error rate (BER) performance of SC transmission. However, the residual ISI after FDE limits the performance improvement. In this paper, we propose a joint use of Tomlinson-Harashima precoding (THP) and FDE to remove the residual ISI. An approximate conditional BER analysis is presented for the given channel condition. The achievable average BER performance is evaluated by Monte-Carlo numerical computation method using the derived conditional BER. The BER analysis is confirmed by computer simulation of the signal transmission.

SUMMARY Turbo coded hybrid ARQ (HARQ) is known as one of the promising error control techniques for high speed wireless packet access. However, in a severe frequency-selective fading channel, the HARQ throughput performance significantly degrades for direct sequence code division multiple access (DS-CDMA) system using rake combining. This problem can be overcome by replacing the rake combining by the frequency-domain equalization (FDE) based on minimum mean square error (MMSE) criterion. In a system with the conventional FDE, the guard interval (GI) is inserted to avoid the inter-block interference (IBI). The insertion of GI reduces the throughput. Recently, overlap FDE that requires no GI insertion was proposed. In this paper, we apply overlap FDE to HARQ and derive the MMSE-FDE weight for packet combining. Then, we evaluate the throughput performance of DS-CDMA HARQ with overlap FDE. We show that overlap FDE provides better throughput performance than both the rake combining and conventional FDE regardless of the degree of the channel frequency-selectivity.

To alleviate network congestion and improve the spectrum efficiency, it is natural to consider operating Long Term Evolution (LTE) on unlicensed spectrum, which is called Unlicensed LTE (U-LTE). In order to get practical experience with U-LTE, NTT DOCOMO and Huawei built up a U-LTE trial system operating over bandwidth of 20MHz in 5.8 GHz unlicensed bands and a field trial was conducted in 2014. The U-LTE system operated in real time and was field tested in typical indoor environments. In this paper, we report the field trial results for both U- LTE and Wi-Fi systems. Our objective is twofold: firstly, coverage and capacity performance in single cell are presented to confirm the potential effectiveness of using U-LTE in the operator network. Secondly, the intra-Radio-Access-Technology (RAT) coexistence performance conducted in different interference scenarios disclosed a challenging problem, i.e., the straightforward introduction of LTE into the unlicensed spectrum is not recommended and interference avoidance technology is necessary in U-LTE.

The exposure index (EI) was proposed as a new X-ray dose index by the International Electrotechnical Commission (IEC) and has since been implemented as an international standard. The EI is calculated by use of an approximation equation under IEC-specified calibration conditions. However, several factors encountered in clinical practice, including the patient’s body thickness and the tube voltage, differ with regard to these calibration conditions. We, therefore, require a solid water phantom-based function that can incorporate the IEC-specified conditions and different subject thicknesses to evaluate the effects of subject thickness on the EI. Here, we assumed average thicknesses of 10 cm for a child, 15 cm for slender patients, and 21 cm for an average adult abdomen and we evaluated errors, that are included in the EI, which were calculated by use of the function. Our results suggested that the EI depends on the subject thickness. At the 21-cm thickness (average adult abdomen), the display EI exhibited a small error level. In contrast, EI values calculated from the calibration conditions exhibited maximum errors that were as high as 34 % at the lower subject thicknesses (10 and 15 cm), suggesting a significant influence of the subject thickness on the EI. In conclusion, the EI should be used cautiously during the examination of children and thin patients, with a complete understanding of the discrepancy revealed by our study results.

A very high-speed wireless access of 100 Mb/s to 1 Gb/s is required for fourth-generation mobile communications systems. However, for such high-speed data transmissions, the channel is severely frequency-selective due to the presence of many interfering paths with different time delays. A promising wireless access technique that can overcome the channel frequency-selectivity and even take advantage of this selectivity to improve the transmission performance is CDMA. There may be two approaches in CDMA technique: direct sequence CDMA and multicarrier CDMA. A lot of attention is paid to MC-CDMA. However, recently it has been revealed that DS-CDMA can achieve good performance comparable to MC-CDMA if proper frequency domain equalization is adopted. This article discusses their similarities and performances. A major transmission mode in 4G systems is packet-based. Automatic repeat request combined with channel coding is a very important technique. Recent research activity on this technique is also introduced.

Small cell enhancement is a key technology to meet future network capacity demands. Dual connectivity has been introduced in LTE Release 12 to enhance the LTE operation in heterogeneous deployments and improve the overall system performance. However, in the scenarios of dual connectivity, due to distributed scheduling in two eNodeBs (eNBs) connected with non-ideal backhaul, the total required transmit power of a user equipment(UE) will easily exceed its maximum capability and power scaling is needed. In this paper, several semi-static power splitting schemes will be proposed based on power spectral density (PSD), path loss and average power consumption ratio to solve this problem. Simulation results demonstrate that our schemes can greatly decrease the probability of power scaling and reduce block error rate (BLER), thus achieving significant gains in uplink throughput.

In recent years, we can easily find the gas-liquid two-phase flow in narrow channel which has straight section and curved section in many industrial products. In order to improve the performance of these industrial products, it is important to clarify the effects of curved section on gas-liquid two-phase flow behavior in narrow channel. In this study, we have measured the pressure loss precisely on straight section and curved section in milli-channel respectively. From the measured pressure loss, we evaluated the mean pressure loss and its intensity. Flow visualization by using high-speed video camera was additionally performed to make clear the relation between modification of pressure loss and flow pattern in curved section. As a result, effects of curved section on gas-liquid two-phase flow in narrow channel were evaluated.

In this paper, we investigate how a distributed antenna network (DAN) offers better throughput performance than a conventional cellular network (CN). In DAN, a group of multiple antennas are distributed in each cell of the CN in order to mitigate the adverse effect of path loss. Moreover, antenna diversity technique can make use of shadowing and multipath fading to improve the transmission performance due to a large spatial diversity gain. In this paper, we consider frequency-domain space-time block coded-joint transmit/ receive diversity (FD-STBC-JTRD) for downlink transmission of single-carrier (SC) DAN. FD-STBC-JTRD uses frequency-domain pre-equalization (pre-FDE) instead of receive FDE to keep the mobile terminal's complexity low, and achieves the full-diversity gain. We show by computer simulation that the transmit power for achieving the required throughput can be significantly reduced compared to the conventional CN.

For the realization of future wireless networks, gigabit wireless technology which can achieve higher-than-1Gbps data transmission with extremely low transmit power is indispensable. We have been studying the distributed antenna network (DAN) and the frequency-domain wireless signal processing. In DAN, many antennas or clusters of antennas are spatially distributed over a service area and they are connected by means of optical fiber links with DAN signal processing center (SPC). A number of distributed antennas cooperatively serve mobile users using spatial multiplexing, diversity, array or relaying technique. In this paper, the recent research advances of gigabit DAN and its related wireless techniques are introduced.

Uplink multi-user direct sequence-code division multi-access (DS-CDMA) suffers from strong multi-user interference (MUI) and self inter-chip interference (ICI) caused by severe frequency-selective fading. In this paper, we propose a joint Tx/iterative Rx frequency-domain equalization (FDE) based on minimum mean square error (MMSE) criterion and successive MUI cancellation (MUIC) for DS-CDMA uplink. In the proposed scheme, each user applies one-tap Tx FDE before transmitting signal. At the base station, joint one-tap Rx FDE and successive MUIC is iteratively performed. The FDE weights of users and base station are jointly optimized based on the MMSE criterion in order to reduce MUI and ICI while exploiting channel frequency-selectivity. Computer simulation results show that the proposed scheme provides much improved bit error rate (BER) performance than the conventional iterative Rx MMSE-FDE with successive MUIC.

Single-carrier distributed antenna network (SC-DAN), in which a group of multiple antennas are distributed in a cell serve a user, can mitigate adverse impacts of path loss, shadowing loss and multipath fading. Frequency-domain space-time block coded-joint transmit/ receive diversity (FD-STBC-JTRD) is attractive for downlink transmission since an arbitrary number of distributed transmit antennas can be used. FD-STBC-JTRD requires the channel state information (CSI) only at the transmitter side and therefore, the complexity problem of mobile terminals can be alleviated. In this paper, we investigate, by computer simulation, the bit error rate (BER) distribution of the SC-DAN downlink. We discuss the impact of the number of distributed antennas involved in FD-STBC-JTRD on the BER outage probability.

Distributed antenna network (DAN) is a promising wireless network to solve the problems arising from shadowing and path lesses as well as frequency-selective fading. Many anntennas are spatially distributed around each base station (BS) so that with a high probability, some antennas can always be visible from a mobile station (MS). Recently, we proposed a 2-dimensional water-filling (2D-WF) transmit diversity for single-carrier (SC) DAN downlink transmission. An MS having single receive antenna was considered. In this paper, we extend the 2D-WF transmit diversity to the case of MS having multiple receive antennas to implement frequency-domain space-time block coded-joint transmit/receive diversity (FD-STBC-JTRD). The channel capacity distribution is evaluated by Monte-Carlo numerical computation method. It is shown that the use of 2 receive antennas maximize the downlink channel capacity while the use of around 5 distributed transmit antennas is sufficient.

In this paper, we propose a spectrum division & adaptive subcarrier allocation for cooperative amplify-and-forward (AF) relay using single carrier-frequency division multiple access (SC-FDMA). To obtain increased frequency diversity gain, the transmit SC signal spectrum is divided into sub-blocks, to each of which a different set of subcarriers (resource block) is adaptively allocated based on the each user's channel condition. The adaptive subcarrier allocation has a tradeoff between the channel capacity and the peak-to-average power ratio (PAPR). We evaluate the outage channel capacity of SC-FDMA using cooperative AF relay and discuss such a tradeoff relationship. Simulation results show that the SC-FDMA using the proposed spectrum division & the adaptive subcarrier allocation can achieve the similar capacity to the orthogonal frequency division multiple access (OFDMA) while keeping lower PAPR property.

In this paper, we propose a new joint transmit/receive equalization technique for single-carrier (SC) block transmissions in a severe frequency-selective fading channel. An iterative frequency-domain inter-symbol interference cancellation (FDIC) is introduced to the joint transmit/receive (Tx/Rx) frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion which was previously proposed by authors. At a receiver, a 1-tap FDE and FDIC are jointly used and they are updated in an iterative manner to achieve larger frequency diversity gain. Since the transmit FDE weight cannot be updated, we introduce a virtual receiver having a receive FDE & FDIC into the transmitter. In the virtual receiver at the transmitter, the same degree of the residual ISI cancellation is assumed to compute the transmit FDE weight, based on the MMSE criterion, matched to the receive FDE & FDIC. The computer simulation results show that the bit error rate (BER) performance is significantly improved by using our proposed scheme.

In this paper, a 2-dimensional water-filling (2D-WF) based transmit weight that maximizes the channel capacity is theoretically derived for the downlink transmit diversity of single-carrier distributed antenna network (SC DAN) in a frequency-selective channel. The 2D-WF transmit weight allocates the transmit power in both transmit antenna dimension and frequency dimension: power allocation across frequencies based on WF theory and across transmit antennas based on maximal ratio transmission (MRT). The cumulative distribution function (CDF) of the achievable channel capacity by 2D-WF transmit diversity is evaluated by the Monte-Carlo numerical computation method. Channel capacities achievable with 2D-WF, MRT, and 1D WF transmit weight are compared. It is shown that the 2D-WF transmit weight provides the highest channel capacity among three transmit weights.

In the next generation high-speed wireless packet access systems, hybrid automatic repeat request (HARQ) is necessary to achieve higher throughput performance. An HARQ with Chase combining (CC) transmits the same coded packet until it is correctly received. The received packets are combined to achieve the time-diversity gain. Recently, we proposed a joint transmit/receive frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion for a broadband single-carrier (SC) signal transmission in a frequency-selective channel. In this paper, we consider SC-HARQ using joint transmit/receive MMSE-FDE and derive a suboptimal set of transmit and receive FDE weights for packet combining. We show by computer simulation that the joint transmit/receive MMSE-FDE offers improved throughput compared to the conventional receive MMSE-FDE.

In the future wireless communication systems, the broadband wireless technology which enables Giga-bps class data services is demanded. Broadband wireless channels become extremely frequency-selective and cause severe inter-symbol interference (ISI). Furthermore, the average received signal power changes in a random manner because of the shadowing and path losses according to the movement of a mobile terminal (MT). Accordingly, the transmission performance severely degrades. Development of some advanced equalization and networking is necessary to overcome the performance degradation. Among them, promising are the frequency-domain equalization (FDE) and distributed antenna network (DAN). The former takes advantage of channel frequency-selectivity to obtain the frequency-diversity gain. In DAN, a group of distributed antennas serve each user to mitigate the negative impact of shadowing and path losses. This article will introduce the recent advances in FDE and DAN for the broadband single-carrier (SC) transmissions.

Broadband wireless channel comprises many propagation paths having different delay times. This results in a severe frequency-selective fading channel. Frequency-domain equalization reception based on the minimum mean square error criterion (called receive MMSE-FDE in this paper) can exploit the channel frequency-selectivity to improve the bit error rate (BER) performance of broadband single-carrier (SC) signal transmissions in a severe frequency-selective fading channel. If the channel state information (CSI) is available at the transmitter side only, transmit MMSE-FDE can be used instead of receive MMSE-FDE. In this paper, we review classical transmit and receive MMSE-FDEs. Then, assuming the perfect knowledge of CSI at both the transmitter and the receiver, we introduce a joint transmit/receive MMSE-FDE that can further improve the BER performance. A set of transmit/receive weights are presented for the joint MMSE-FDE and evaluate the achievable BER performance.

Recently, multi-carrier code division multiple access (MC-CDMA) has been attracting much attention as a broadband wireless access technique for the next generation mobile communications systems. Frequency-domain equalization (FDE) based on the minimum mean square error (MMSE) criterion can take advantage of the channel frequency-selectivity and improve the average bit error rate (BER) performance due to frequency-diversity gain. However, conventional MC-CDMA requires the insertion of guard interval (GI) and this reduces the transmission efficiency. Overlap FDE technique has been proposed that requires no GI insertion. Recently, we showed that MC-CDMA using overlap FDE can provide almost the same BER performance as the conventional MC-CDMA downlink using the GI insertion. However, our previous work assumed the ideal channel estimation. In this paper, we propose a pilot assisted channel estimation technique suitable for MC-CDMA downlink using overlap FDE and evaluate the BER performance by computer simulation.

High speed packet access is the core technology of the next generation mobile communication systems. Turbo coded hybrid ARQ (HARQ) is known as one of the promising error control techniques. For direct sequence code division multiple access (DS-CDMA), frequency-domain equalization (FDE) based on minimum mean square error (MMSE) criterion can replace the well known rake combining with much improved transmission performance. However, the insertion of guard interval (GI), which is required for conventional FDE, reduces the throughput. Recently, overlap FDE that requires no GI insertion was proposed for DS-CDMA. In this paper, we evaluate the throughput of DS-CDMA HARQ with overlap FDE.

Case: While working in a factory, a thirty-five-year-old man injured his right forearm and was then diagnosed with acute compartment syndrome. Ruptures of the flexor and extensor tendons were revealed via single volar and dorsal incisions. End-to-side transfer with use of the remaining extensor tendons was performed; the end of the extensor indicis proprius tendon was sutured to the side of the extensor digitorum communis tendon of the middle finger, and the extensor pollicis longus tendon was sutured to the extensor pollicis brevis tendon. Conclusion: In cases of high-energy injuries, associated tendon rupture should be considered.

Multicode direct-sequence code division multiple access (DS-CDMA) can flexibly support multimedia services with various data rates simply by changing the code multiplexing order. The use of simple one-tap frequency-domain equalisation (FDE) at a receiver is known to improve the bit error rate (BER) performance of multicode DS-CDMA in a severe frequency-selective fading environment. However, the BER performance improvement is limited due to the presence of the residual inter-chip interference (ICI). The authors propose a joint transmit/receive minimum mean square error (MMSE) FDE, which carries out one-tap transmit FDE and one-tap receive FDE jointly based on the MMSE criterion. The authors theoretically derive a suboptimal set of transmit and receive FDE weights and investigate the BER performance improvement by computer simulation in a freqeuncy-selective Rayleigh fading channel. The proposed scheme improves the received signal-to-interference plus noise ratio after despreading, and consequently, the BER performance can be significantly improved compared to the conventioal receive MMSE-FDE by (a) making the variations in the equivalent channel gain shallower to reduce the residual ICI for large code multiplexing order U and (b) allocating the transmit power to the frequencies having good condition to improve the received signal-to-noise ratio for a small U. This is conformed by the computer simualtion.