Design of a continuous-wave tunable terahertz source using waveguide-phase-matched GaAs

A novel source of continuous-wave terahertz radiation based on difference frequency generation (DFG) in GaAs crystal is proposed. Phase matching is provided using integration of appropriate optical and terahertz waveguides based on dispersive properties of GaAs. The output frequency can be tuned between 0–3.5 THz by tuning the incident wavelengths in the range of 1.5–1.6 µm

Proposal for Compact Optical Filters Using Large Index Step Binary Supergratings

Compact optical filters are proposed using an aperiodic grating of fixed element size [i.e., a binary supergrating (BSG)] with a large refractive index step. These filters allow for almost arbitrary wavelength filtering, yet they are more compact than previous demonstrations of BSG. The filters are designed using a combination of Boolean particle swarm optimization (B-PSO) and a one-dimensional transfer matrix method. To demonstrate the compact device size, several 50-mum-long single-wavelength transmission filters are demonstrated theoretically, each having a different wavelength while using the same structural parameters. A multiwavelength filter is also proposed in an 80-mum-long structure to show the versatility of the large refractive index step BSG. A genetic algorithm is substituted for the B-PSO; however, B-PSO shows better performance here. This work may be applied to produce compact optical filters for intrachip optical networks and compact tunable lasers, while using existing single-step photolithography processes

Ionic mass transfer at point electrodes located at cathode support plate in an electrorefining cell in presence of rectangular turbulent promoters

Current density plays a major role in deciding the plant size, current efficiency, and energy consumption in electrorefining cells. In general, operating current density will be 40% of the limiting current density. Forced circulation of the electrolyte in the presence of promoters improves the mass transfer coefficient. In the present study, rectangular turbulence promoters are fitted at the bottom side of the cell to improve the mass transfer coefficient at the cathode support plate. The limiting current density technique is used to measure the mass transfer coefficient. The variables covered in the present study are the effects of flow rate, promoter height, and spacing among the promoters. The electrolyte consists of copper sulfate and sulphuric acid. At a regulated flow rate, the electrolyte is pumped from the recirculation tank to the cell through an intermediate overhead tank. The limiting current density increased with an increasing flow rate in the presence of promoters, and thus the overall mass transfer coefficient on the cathode support plate also improved. With an increase in the flow rate of the electrolyte from 6.67 × 10−6 to 153.33 m3/s, limiting current density increased from 356.8 to 488.8 A/m2 for spacing of 0.30 m, with a promoter height of 0.01 m. However, it is noteworthy that when the promoter height is increased from 0.01 to 0.07 m, the overall mass transfer coefficient is found to increase up to 60%, but with the further increase in the promoter height to 0.30 m the mass transfer coefficient starts to decrease. Therefore, the optimized cell parameters are established in this work. The current sustainable concept of employing rectangular turbulence promoters will bring benefits to any precious metal refining or electrowinning tank house electrolytes

Simple facet joint repair with dynamic pedicular system: Technical note and case series

Purpose: Facet joints are important anatomical structures for the stability of spine. Surgical or degenerative damage to a facet joint may lead to spinal instability and causes clinical problems. This article explains the importance of facet joints, reviews facet replacement systems, and describes a simple and effective method for facet replacement after surgical removal of facet joints. Materials and Methods: Ten patients were operated with the diagnosis of unilateral nerve root compression secondary to facet degeneration. The hypertrophic facet joints were removed with microsurgical techniques and the roots were decompressed. Then, a unilateral artificial facet joint was created using two hinged screws and a dynamic rod. Results: The clinical outcome of all the patients was determined good or excellent at second and last follow-up (mean 13.3 months) controls using visual analog scale (VAS) and Oswestry Disability Index (ODI) scores. Radiological evaluations also demonstrated no implant-related complications. Conclusions: The authors suggest that, if removal of a facet joint is necessary to decompress the nerve roots, the joint can be replaced by a construct composed of two hinged screws connected by a dynamic rod. This simple system mimics the function of a normal facet joint and is an effective technique for unilateral facet joint replacement

Assessment of body mass index and hand anthropometric measurements as independent risk factors for carpal tunnel syndrome

The goal of this study was to clarify the role of body mass index (BMI) (weight divided by square of height; kg/m2) and hand anthropometric measurements as independent risk determinants in the development of carpal tunnel syndrome (CTS) and their relationship to the severity of CTS. A total of 131 patients with clinical symptoms of CTS and 131 normal subjects were enrolled, of whom 121 were female both in the CTS cases and the controls. All cases were electrodiagnostically confirmed and assigned to three severity groups. BMI, wrist ratio, shape index, digit index and hand length/height ratio were measured in all participants. Mean values for each item were compared between cases and controls and severity subgroups. A logistic regression analysis was performed to determine independent CTS risk factors. The mean values of BMI, wrist ratio and shape index were significantly higher in all CTS patients and females compared to controls, whereas in males only BMI and wrist ratio were higher. The patients in the mild severity subgroup had a significantly lower age and wrist ratio. BMI, wrist ratio and shape index were found to be independent risk factors of CTS development in all patients and females. Our study showed BMI, wrist ratio and shape index as independent risk factors for CTS. These findings are of potential anatomical and clinical importance and outline the risk factors of anatomical malfunction of the wrist in CTS. (Folia Morphol 2008; 67: 36-42

Design of a continuous-wave tunable terahertz source using waveguide-phase-matched GaAs

A novel source of continuous-wave terahertz radiation based on difference frequency generation (DFG) in GaAs crystal is proposed. Phase matching is provided using integration of appropriate optical and terahertz waveguides based on dispersive properties of GaAs. The output frequency can be tuned between 0–3.5 THz by tuning the incident wavelengths in the range of 1.5–1.6 µm

Proposal for Compact Optical Filters Using Large Index Step Binary Supergratings

Compact optical filters are proposed using an aperiodic grating of fixed element size [i.e., a binary supergrating (BSG)] with a large refractive index step. These filters allow for almost arbitrary wavelength filtering, yet they are more compact than previous demonstrations of BSG. The filters are designed using a combination of Boolean particle swarm optimization (B-PSO) and a one-dimensional transfer matrix method. To demonstrate the compact device size, several 50-mum-long single-wavelength transmission filters are demonstrated theoretically, each having a different wavelength while using the same structural parameters. A multiwavelength filter is also proposed in an 80-mum-long structure to show the versatility of the large refractive index step BSG. A genetic algorithm is substituted for the B-PSO; however, B-PSO shows better performance here. This work may be applied to produce compact optical filters for intrachip optical networks and compact tunable lasers, while using existing single-step photolithography processes

PEMBERDAYAAN PEREMPUAN BERBASIS KREATIFITAS DI DUSUN MOJOREJO DESA JUNREJO KOTA BATU

Keadaan perekonomian saat ini sangat memprihatinkan khususnya di Indonesia yang terdapat berbagai permasalahan yang menyangkut mengenai kehidupan bermasyarakat, antara lain masalah kemiskinan, masalah pengangguran, masalah lingkungan hidup, dan lain-lain. Permasalahan tersebut timbul akibat semakin meningkatnya keadaan ekonomi yang tidak disesuaikan dengan kondisi masyarakat. Khususnya masyarakat menengah kebawah. Kemiskinan menjadi masalah yang penting saat ini di Indonesia, sehingga menjadi suatu fokus perhatian bagi pemerintah Indonesia. Masalah kemiskinan ini sangatlah kompleks karena berkaitan dengan aspek sosial, ekonomi, budaya, dan aspek lainnya. Kemiskinan terus menjadi masalah fenomenal di belahan dunia, khususnya Indonesia yang merupakan negara berkembang. Kemiskinan telah membuat jutaan anak tidak bisa mengenyam pendidikan, kesulitan membiayai kesehatan, kurangnya tabungan dan investasi, dan masalah lain yang menjurus ke arah tindakan kekerasan dan kejahatan. Kemisikinan menjadi salah satu fenomena masalah yang kerap kita temui di majalah, surat kabar, ataupun berita online lainnya. Dinas sosial Kota Batu setidaknya mencatat ada 2.339 keluarga miskin sedangkan badan pusat statistik menerangkan jumlah keluarga miskin mencapai 2.600 keluarga miskin. Ini cukup membuktikan untuk menjelaskan bahwa masih banyak keluarga Kota Batu yang masih harus berjuang hanya untuk sekedar membiayai anaknya masuk sekolah. Pemberdayaan menjadi salah satu alternatif untuk menyelesaikan masalah terkait dengan pengentasan kemiskinan. Dalam penelitian ini terkait dengan program pemberdayaan yang dilakukan oleh kelompok mahasiswa Universitas Muhammadiyah Malang dan didanai oleh DIKTI dari Program Kreatifitas Mahasiswa (PKM) yang mana saya termasuk dalam kelompok tersebut. Pengabdian masyarakat dalam bentuk pemberdayaan masyarakat ini mempunyai subyek pemberdayaan perempuan dusun Wonorejo Desa Junrejo Kota Batu. Proses pemberdayaan dilakukan selama tiga bulan di dusun setempat

Rb-87-stabilized 375-MHz Yb:fiber femtosecond frequency comb

We report a fully stabilized 1030-nm Yb-fiber frequency comb operating at a pulse repetition frequency of 375 MHz. The comb spacing was referenced to a Rb-stabilized microwave synthesizer and the comb offset was stabilized by generating a super-continuum containing a coherent component at 780.2 nm which was heterodyned with a 87Rb-stabilized external cavity diode laser to produce a radio-frequency beat used to actuate the carrier-envelope offset frequency of the Yb-fiber laser. The two-sample frequency deviation of the locked comb was 235 kHz for an averaging time of 50 seconds, and the comb remained locked for over 60 minutes with a root mean squared deviation of 236 kHz