Pembangunan Proto Type Kuliah On-line Menggunakan Teknologi Active Optikal Network

Transformasi ilmu pengetahuan merupakan hal yang sangat penting untuk meningkatkan kualitas pendidikan. Proses transformasi ilmu pengetahuan dapat dilakukan dengan berbagai cara.seperti yang diungkapkan oleh Tjutju Soendari [2]. Dengan adanya perkembangan teknologi jaringan computer dan adanya perkembangan dalam fiber optik sebagai media yang dapat mengantarkan informasi secara real time dengan kapasitas data yang besar dan dalam waktu yang singkat, telah mendukung berkembangnya sistem kuliah on-line. Hal ini dapat menunjang proses perkuliahan yang memiliki kelas paralel seperti halnya proses perkuliahan yang ada di Telkom apllied science school yang memiliki lebih dari dua kelas untuk setiap mata kuliahnya sehingga dengan adanya system ini memungkinkan jumlah dosen yang dibutuhkan untuk system perkuliahan ini berkurang. Sistem perkuliahan on-line membutuhkan transfer data yang bersifat real time dengan kualitas gambar yang baik. Sebuah prototype perkuliahan on-line yang dibangun untuk menghubungkan 3 buah client yang berada pada ruangan yang berbeda tetapi saling terhubung kedalam sebuah jaringan, menunjukkan bahwa jaringan yang menggunakan teknologi Active Optikal Network berbasis active splitter menunjukkan nilai delay 4,54 ms sedangkan delay untuk jaringan berbasis kabel UTP adalah 54,5 ms. Sehingga perbandingan nilai delay ini menunjukkan kuliah on-line lebih baik jika menggunakan jaringan serat optik

Realization of a Second Harmonic Antenna for Rural Communications*

In this research, an active antenna operated at the second harmonic frequency is investigated, and is implemented using microstrip antenna material. The antenna consists of a FET oscillator which plays as a fundamental frequency oscillator and a frequency multiplier, and a patch antenna resonated at the second harmonic frequency as the radiator. A maximum second-harmonic output power can be extracted when the load impedance of the oscillator is optimized both at the fundamental and at the second harmonic frequencies. A rectangular patch antenna is used to radiate the second harmonic output power from the oscillator. The patch impedance is matched resistively at the second harmonic frequency. The patch antenna is fabricated using Diclad 522 microstrip substrates (relative permitivity r = 2.5) with a dielectric thickness of 1.57 mm. A GaAs FET AT-8250 transistor is used as an oscillator and a frequency multiplier and acts as the active component. Fundamental frequency is designed at 2,4 GHz band, so that the second harmonic frequency operates at 4,8 GHz band. The frequency is chosen to facilitate and to extend the needs of communications in rural areas using the unlicensed Industrial Scientific, and Medical (ISM) band. Operating the communication infrastructures intended for the use at 2.4 GHz band at its second harmonic frequency, is intended to alleviate interference levels at 2.4 GHz

Improved Predictive Power Control of Cdma System in Rayleigh Fading Channel

In this paper an improved prediction-based power control is proposed for code division multiple access (CDMA)systems in Rayleigh fading channel environments. One of the most serious problems which degrades the performanceof power control algorithm is the effect of feedback delay. To overcome the effect of feedback delay, power controlneeds to employ prediction algorithm which utilises the correlation property of the past channel samples measurementsto predict the future sample values. In CDMA power control, however, the correlation property of channelmeasurements is destroyed because the transmit power is continuously updated for each power control interval. Theprediction algorithm in this paper uses the recursive least square (RLS) technique and an improved predictor algorithmis proposed to compensate for the channel correlation. The result shows that the performance of improved predictivepower control proposed in this paper evaluated in terms of bit error rate (BER) as a function of bit energy-tointerferencepower density ratio Eb/Io improved significantly from that of the conventional predictor

Variable Step Closed Loop Power Control with Space Diversity for Low Elevation Angle High Altitude Platforms Communication Channel [Langkah Variabel Kontrol Daya Loop Tertutup Dengan Keragaman Ruang Untuk Sudut Elevasi Rendah Pada Kanal Komunikasi HAPs]

This paper proposes variable step closed loop power control algorithm combined with space diversity to improve the performance of High Altitude Platforms (HAPs) communication at low elevation angle using Code Division Multiple Access (CDMA). In this contribution, we first develop HAPs channel model which is derived from experimental measurement. From our experiment, we found HAPs channel characteristic can be modeled as a Ricean distribution because the presence of line of sight path. Different elevation angle resulting different K factor value. This value is then used in Signal to Interference Ratio (SIR) based closed loop power control evaluation. The variable step algorithm is simulated under various elevation angles with different speed of mobile user. The performance is presented in terms of user elevation angle, user speed, step size and space diversity order. We found that the performance of variable step closed-loop power control less effective at low elevation angle. However our simulation shows that space diversity is able to improve the performance of closed loop power control for HAPs channel at low elevation angle.*****Kajian ini mengusulkan suatu algoritma kontrol daya langkah variabel loop tertutup dikombinasikan dengan keragaman ruang untuk meningkatkan kinerja komunikasi High Altitude Platforms(HAPs) pada sudut elevasi rendah menggunakan Code Division Multiple Access (CDMA). Kami berkontribusi untuk mengembangkan model kanal HAPs yang berasal dari pengukuran eksperimental sebelumnya. Dari percobaan tersebut, kami menemukan karakteristik kanal HAPs yang dapat dimodelkan sebagai distribusi Ricean karena kehadiran jalur tanpa penghalang. Eksperimen menunjukkan bahwa perbedaan sudut elevasi menghasilkan perbedaan nilai factor K. Nilai ini kemudian digunakan dalam Signal to Interference Ratio (SIR) berbasiskan evaluasi kontrol daya loop tertutup. Algoritma langkah variabel disimulasikan dibawah sudut elevasi yang berbeda dengan kecepatan yang berbeda dari pengguna vobile. Kinerja tersebut disajikan dalam hal sudut elevasi pengguna, kecepatan pengguna, ukuran langkah dan ketertiban ruang keanekaragaman. Kami menemukan bahwa kinerja langkah variabel kontrol daya loop tertutup kurang efektif pada sudut elevasi rendah. Namun simulasi kami menunjukkan bahwa ruang keragaman mampu meningkatkan kinerja kontrol daya loop tertutup untuk kanal HAPs di sudut elevasi rendah

Pembuatan Katalis H-zeolit dengan Impregnasi Ki/kio3 dan Uji Kinerja Katalis untuk Produksi Biodiesel

H-Zeolite catalysts synthesized from natural zeolite include chemical treatment process stages, screening, washing, impregnation KI/KIO3 and physical treatment. The objective of this research is to study characteristics of catalyst that was impregnated KI / KIO3 with surface area analysis, X-Ray Diffraction (XRD) and performance test of catalyst for production of biodiesel. The results showed that the surface area of ​​the catalyst by 27.236 m2/ g at a concentration of 5% KI. XRD analysis of the value obtained at 2-θ peak at 23.627o zeolite indicating that KI was impregnated on H-zeolite catalyst. The catalyst was tested for production of biodiesel using palm oil with conventional methods for 3-hour temperature of 70-80oC. The Result for conversion Fatty Acid Methyl Ester (FAME) had maximum value on 87.91% at a concentration of catalyst impregnation variable KIO3 5%

Emerging Roles for MicroRNAs in Perioperative Medicine

MicroRNAs (miRNAs) are small, non-protein-coding, single-stranded RNAs. They function as posttranscriptional regulators of gene expression by interacting with target mRNAs. This process prevents translation of target mRNAs into a functional protein. miRNAs are considered to be functionally involved in virtually all physiologic processes, including differentiation and proliferation, metabolism, hemostasis, apoptosis, and inflammation. Many of these functions have important implications for anesthesiology and critical care medicine. Studies indicate that miRNA expression levels can be used to predict the risk for eminent organ injury or sepsis. Pharmacologic approaches targeting miRNAs for the treatment of human diseases are currently being tested in clinical trials. The present review highlights the important biological functions of miRNAs and their usefulness as perioperative biomarkers and discusses the pharmacologic approaches that modulate miRNA functions for disease treatment. In addition, the authors discuss the pharmacologic interactions of miRNAs with currently used anesthetics and their potential to impact anesthetic toxicity and side effects

Motivation rulers for smoking cessation: a prospective observational examination of construct and predictive validity

BACKGROUND: Although popular clinically, the psychometric properties of motivation rulers for tobacco cessation are unknown. This study examined the psychometric properties of rulers assessing importance, readiness, and confidence in tobacco cessation. METHODS: This observational study of current smokers was conducted at 10 US emergency departments (EDs). Subjects were assessed during their ED visit (baseline) and reassessed two weeks later. We examined intercorrelations between the rulers as well as their construct and predictive validity. Hierarchical multinomial logistic regressions were used to examine the rulers\u27 predictive ability after controlling for covariables. RESULTS: We enrolled 375 subjects. The correlations between the three rulers ranged from 0.50 (between Important and Confidence) to 0.70 (between Readiness and Confidence); all were significant (p \u3c 0.001). Individuals in the preparation stage displayed the highest motivation-ruler ratings (all rulers F 2, 363 \u3e/= 43; p \u3c 0.001). After adjusting for covariables, each of the rulers significantly improved prediction of smoking behavior change. The strength of their predictive ability was on par with that of stage of change. CONCLUSION: Our results provide preliminary support for the psychometric soundness of the importance, readiness, and confidence rulers

Improved care of acute exacerbation of chronic obstructive pulmonary disease in two academic emergency departments

Background: Although several chronic obstructive pulmonary disease (COPD) practice guidelines have been published, there is sparse data on the actual emergency department (ED) management of acute exacerbation of COPD (AECOPD). Aims: Our objectives were to examine concordance of ED care of AECOPD in older patients with guideline recommendations and to evaluate whether concordance has improved over time in two academic EDs. Methods: Data were obtained from two cohort studies on AECOPD performed in two academic EDs during two different time periods, 2000 and 2005–2006. Both studies included ED patients, aged 55 and older, who presented with AECOPD, and cases were confirmed by emergency physicians. Data on ED management and disposition were obtained from chart review for both cohorts. Results: The analysis included 272 patients: 72 in the 2000 database and 200 in the 2005–2006 database. The mean age of the patients was 72 years; 50% were women and 80% white. In 2005–2006, overall concordance with guideline recommendations was high (for chest radiography, pulse oximetry, bronchodilators, all ≥ 90%), except for arterial blood gas testing (7% among the admitted) and discharge medication with systemic corticosteroids (42%). Compared to the 2000 data, the use of systemic corticosteroids in the ED improved from 53 to 77% [absolute improvement: 24%, 95% confidence interval (CI): 11–37%], and the use of antibiotics among the patients with respiratory infection symptoms improved from 56 to 78% (absolute improvement: 22%, 95% CI: 6–38%). Conclusions: Overall concordance with guideline-recommended care for AECOPD was high in two academic EDs, and some emergency treatments have improved over time