Idam Arif
Institut Teknologi Bandung

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Model Inklusi Silinder dalam Jaringan Homogen untuk Elastografi Biomedik Idam Arif; Astalini Astalini
Jurnal Matematika & Sains Vol 10, No 4 (2005)
Publisher : Institut Teknologi Bandung

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Abstract

A cylindrical inclusion model in a tissue matrix is proposed for biomedical elastography. Solutions of elasticity equation are applied to observe the effects of the inclusion on the distribution of a uniform stress given to the matrix. The inclusion and the matrix are assumed to be isotropic, homogen, and linear. The obtained analytical solutions are illustrated in the form of graphics for breast tumors and cysts. It is shown that the effects are located in the region less than 3R, with R being the inclusion radius. If the inclusion is stiffer than the matrix (µb>µt), then the displacement in z direction is negative and is positive in y direction. It means that the strain and stress components in z direction (ezz,szz) are negative and (eyy,syy) are positive in y direction. If the inclusion is softer than the matrix (µb>µt) then the displacement in z and y directions is negative. Therefore the strain and stress components in z direction and in y direction both are also negative.
Calcium Release from Cell Walls of Pea Epicotyls Caused by Proton Extrusion during Fusicoccin Action Idam Arif
Jurnal Matematika & Sains Vol 16, No 2 (2011)
Publisher : Institut Teknologi Bandung

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Abstract

Proton and calcium net fluxes were measured simultaneously during fusicoccin action on peeled Pisum sativum L. epicotyl segments. The measurement employs ion selective microelectrodes to determine the fluxes. The membrane potential of parenchymal cells during the action was also measured. Fusicoccin at 10-3 mol m-3 causes immediate proton and calcium effluxes reaching about 60 and 80 nmol m-2 s-1 respectively within 40 minutes. It also causes membrane hyperpolarization of about -22 mV. The responses to 10-2 mol m-3 fusicoccin are larger. The data fit the Weak-Acid Donnan Manning model for exchange between wall calcium and extruded protons during fusicoccin action on peas. Keywords: Wall calcium, Ion exchange, Proton extrusion, Fusicoccin. Pelepasan Kalsium dari Dinding Sel Epikotil Kacang Polong yang Disebabkan oleh Ekstrusi Proton Selama Aksi Fusicoccin Abstrak Flux netto ion proton dan kalsium diukur secara bersamaan selama aksi fusicoccin pada segmen epikotil Pisum sativum L. yang dikupas epidermisnya.  Pengukuran tersebut memakai mikroelektroda yang selektif hanya pada suatu ion untuk menentukan besarnya flux ion tersebut. Potensial membran sel parenkim selama aksi fusicocin tersebut juga diukur. Fusicoccin dengan konsentrasi 10-3 mol m-3 langsung menyebabkan efflux ion proton dan kalsium yang masing masing mencapai sekitar 60 dan 80 nmol m-2 s-1 dalam waktu 40 menit. Fusicoccin dengan konsentrasi yang sama  juga menyebabkan hiperpolarisasi membran sel sekitar -22 mV. Fusicoccin dengan konsentrasi yang lebih tinggi, yaitu10-2 mol m-3, menyebabkan respon yang  lebih besar. Data tersebut bersesuaian dengan model Weak-Acid Donnan Manning yang menjelaskan pertukaran antara kalsium yang terkondensasi dalam dinding sel dengan proton yang keluar dari dalam sel selama aksi fusicoccin pada kacang polong. Kata kunci: Kalsium dinding sel, Pertukaran ion, Ekstrusi proton, Fusicoccin.
Respon Berbagai Bentuk, Ukuran dan Bahan Elektroda Pada Pengayaan Elektrolisis Tritium dalam Sampel Air Hidayanto, Eko; Tjahaja, Poppy Intan; Arif, Idam
BERKALA FISIKA Vol 12, No 3 (2009): Berkala Fisika
Publisher : BERKALA FISIKA

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Abstract

Experiments were carried out to investigate the effects of various forms, sizes and materials of electrodes in the electrolytic enrichment for the determination of tritium concentration in water sample. Electrodes were made in several forms: square plate, cylinder and spiral. The electrolytic enrichment was carried out by conducting electric current to the electrodes in electrolytic cell at 150C filled with water sample, until the water volume is reduced to 10% from the initial volume. The concentrated water were then mixed with scintillate solution, and then counted using Liquid Scintillation Counter (LSC). The results show that the appropriate electrodes is nickel square plate with the recovery fraction and the enrichment factor respectively are 73.73% and 7.373
Analisis Spektral Daya dan Koherensi EEG Pada Anak Penderita Autism Spectrum Disorders (ASD) Handayani, Nita; Pratama, Sra Harke; Khotimah, Siti Nurul; Arif, Idam; Haryanto, Freddy
Wahana Fisika Vol 2, No 2 (2017): Desember
Publisher : Universitas Pendidikan Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17509/wafi.v2i2.9374

Abstract

Autism Spectrum Disorders (ASD) adalah kondisi neurodevelopmental yang berkaitan dengan defisit dalam fungsi eksekutif, emosi, bahasa, dan komunikasi sosial. Beberapa teknik neuroimaging dan neurofisiologi digunakan untuk memahami hubungan antara fungsionalitas otak dan perilaku autis. Quantitative Electroencephalography (QEEG) adalah sebuah teknik non-invasif yang dapat digunakan untuk memberikan gambaran fungsionalitas otak melalui beberapa besaran fisis yang dikaji. Pada paper ini akan dibahas tentang karakteristik sinyal listrik otak pada penderita austis berdasarkan analisis QEEG.  Perekaman sinyal otak menggunakan Emotiv Epoc 14 channel (AF3, F7, F3, FC5, T7, P7, O1, O2, P8, T7, FC6, F4, F8, AF4) dan 2 channel referensi (CMS dan DRL). Jumlah subjek uji dalam penelitian sebanyak 6 anak penderita autis dan 5 anak sehat sebagai kontrol dengan rentang usia antara 10-15 tahun. Perekaman otak dilakukan pada kondisi rileks dan mata terutup selama 15 menit. Metode analisis data meliputi pre-processing data EEG untuk menghilangkan noise dan artefak, perhitungan spektral daya menggunakan periodogram Welch, dan analisis konektivitas fungsional otak dengan menghitung besarnya koherensi intra-hemisphere dan inter-hemisphere. Dari hasil studi diperoleh bahwa pada anak autis terjadi peningkatan spektral daya pada pita delta dan penurunan spektral daya pada pita alpha dibandingkan dengan subjek kontrol. Analisis konektivitas fungsional otak pada anak autis menunjukkan nilai koherensi intra-hemisphere dan inter-hemisphere yang lebih rendah pada pita delta dan theta, khususnya pada area frontal. QEEG dapat digunakan untuk karakterisasi sinyal otak pada penderita autis dan membedakannya dari subjek normal.      Kata Kunci   :  Retardasi Mental; Spektral Daya; Koherensi; EEG;  Sinyal Otak Autism Spectrum disorder (ASD) is a neurodevelopmental disorder associated with deficits in executive function, emotions, language, and social communication. Several neuroimaging and neurophysiology techniques are used to understand the relationship between brain functionality and autistic behavior. Quantitative Electroencephalography (QEEG) is a non-invasive technique that can be used to illustrate the functionality of the brain through the analysis of several physical quantities. This paper will discuss about the characteristics of electrical brain signals in austistic children based on QEEG analysis. Recording of brain signals using  Emotiv Epoc 14-channels (AF3, F7, F1, O2, P8, T7, FC6, F4, F8, AF4) and 2 reference channels (CMS and DRL). The number of test subjects in the study were 6 autistic children and 5 healthy children as controls with an age range between 10-15 years old. Brain recording performed on resting state and eyes closed for 15 minutes. The methods of analysis data includes pre-processing EEGs data to remove noise and artifacts, power spectral analysis using Welch Periodogram, and brain functional connectivity analysis by calculating the magnitude of intra-hemisphere and inter-hemisphere coherences. The results of the study found that an increased of power spectral in the delta band and a decreased of power spectral in the alpha band in autistic children compared to control subjects. Analysis of functional connectivity of the brain in autistic children shows lower intra-hemisphere and inter-hemisphere coherences in the delta and theta bands, particularly in the frontal area. QEEG can be used to characterized brain signals in autistic children and differentiated them from the normal subjects.          Keywords  : Mental Retardation; Power Spectral; Coherence; EEG; Brain Signal
Dose Volume Product (DVP) As Descriptor for Estimating Total Energy Imparted to Patient Undergoing CT Examination Choirul Anam; Freddy Haryanto; Rena Widita; Idam Arif; Geoff Dougherty
Journal of Medical Physics and Biophysics Vol 3, No 1 (2016)
Publisher : Indonesian Association of Physicists in Medicine (AIPM/AFISMI)

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Abstract

The purpose of this study is to expand a descriptor for estimating the total energy imparted to a patient undergoing a CT examination and to investigate its relationship to the currently used descriptor. Estimating the total energy imparted to a patient has previously been characterized by dose length product (DLP). We propose a descriptor which we call the dose volume product (DVP), defined as the product of the size specific-dose estimate (SSDE) and the volume irradiated in the patient (V). We also present algorithm to automate the calculation of DVP. There are several steps in calculating the DVP: the first is to contour the patient automatically, the second is to calculate the area of patient in every single slice, the third is to calculate the volume of the radiated part of the patient, the fourth is to calculate the water equivalent diameter (DW) automatically, the fifth is to calculate the SSDE, and the last is to calculate the DVP. To investigate the effectiveness of the algorithm, we used it on images of phantoms and patients. The results of this study show that the automated calculations of DVP for both body and head phantoms were in good agreement with theoretical calculations. The differences between them were within 2%. DVP and DLP had a linear relationship with R2 = 0.971 (slope 1099 cm2, 95% confidence interval (CI), 1047 to 1157 cm2) and R2 = 0.831 (slope 248.6 cm2: CI, 237.6 to 259.7 cm2), for thorax and head patients respectively.