ABSTRAKBadai guntur merupakan salah satu fenomena cuaca yang sering terjadi di wilayah Indonesia. Singkatnya durasi hidup badai guntur menyebabkan kejadian ini sulit sekali diprediksi. Analisis indeks stabilitas udara adalah salah satu cara yang digunakan untuk memprediksi peluang kejadian badai guntur. Metode Total -Totals Index, Indeks K dan Indeks Severe Weather Threat (SWEAT) merupakan beberapa metode analisis indeks stabilitas udara yang dikembangkan di daerah lintang tinggi dan sering digunakan untuk memprediksi peluang terjadinya badai guntur di Indonesia. Hasil pengolahan data selama periode tahun 2000 -2009 menunjukkan bahwa interval yang telah ada dari masing -masing indeks untuk wilayah lintang tinggi tidak cocok untuk digunakan di Stasiun Meteorologi Cengkareng. Untuk Total -Totals Index peluang terbesar terjadinya badai guntur pada nilai interval 42 -46, berbeda dengan nilai interval yang telah dirumuskan yaitu sebesar 44. Demikian juga dengan interval indeks K yang menunjukan terjadinya badai guntur umumnya pada interval 29 -37 berbeda dengan interval yang telah dirumuskan yaitu sebesar >25, sedangkan untuk indeks SWEAT peluang terbesar terjadinya badai guntur pada interval 135 -239 dengan prosentase kejadian sebesar 91,86% berbeda dengan interval yang sudah ada dimana badai guntur umumnya terjadi pada interval diatas nilai 230.Kata kunci: badai guntur, indeks total -totals, indeks K, indeks SWEAT. ABSTRACTThunderstorm is one of weather phenomena which mostly occurred in Indonesia. It is difficult to predict thunderstorm because of its short life cycle. An analysis of stability indices can be used to predict thunderstorm. Total -Totals Index, K Index and Severe Weather Threat (SWEAT) Index are some indices used in subtropic and also used in Indonesia to predict thunderstorm. The analysis of data from 2000 -2009 shows that interval used in subtropic not suitable for Cengkareng Meteorological Station. Thunderstorm mostly occur in interval 42 -46 for Total -Totals Index, different from the interval using in subtropic region which is 44. For the K-index, thunderstorms mostly occur with interval 29 -37 but thunderstorm had been formulated to mostly occur with interval >25. Meanwhile, for SWEAT index thunderstorm predict mostly occur for interval 135 -239 (91.86%) different from the inverval used in subtropic which is >230.

Telah dilakukan penelitian pengaruh variasi jarak antara sumber radiasi dengan<br />titik pengukuran terhadap sebaran radiasi hambur pada pesawat sinar-X pada saat<br />pemeriksaan tomografi ginjaldi Rumah Sakit Pusat Angkatan Darat Gatot Soebroto<br />sehingga dihasilkan kontur sebaran radiasi hambur dengan menggunakan perangkat lunak<br />surfer.Penelitian ini menggunakan phantom abdomen dengan kondisi penyinaran faktor<br />eksposi tetap meliputi tegangan tabung 70 kV, arus tabung dan waktu penyinaran 50 mAs.<br />Sampel dalam penelitian adalah jarak 50 cm, 100 cm, dan 150 cm dari titik tengah pusat<br />pemeriksaan ke titik pengukuran. Pengukuran ini dilakukan dengan alat ukur<br />termoluminesensi dosimeter (TLD-100 LiF). Hasil penelitian menunjukkan bahwa jumlah<br />paparan radiasi akan semakin menurun terhadap penambahan jarak, sehingga dapat<br />mengetahui titik-titik / tempat yang aman terhadap paparan radiasi.

Modification of surface and urban morphological changes, resulting in disruption of thermodynamic and dynamics properties in sub lowest layer of atmosphere, lead air temperature in downtown area higher than suburban. Study aims to analyze components of energy balance dense area of Jakarta using single-layer urban canopy model. H flux in solid area was dominant at noon. LE flux from dense area was very low Maximum intensity nocturnal heat island in dense areas was 2.5 °C. Higher value of h/w, S↓ received by wall and road decreases, causing H flux emitted by surface weakened. Instead L↑ emission trapped increases. The most dominant component that controls the balance of radiation and energy dense area are S↓ radiation, and H emission. Roof and road most active to respond heat during the day, and wall at night. Energy received or emitted by roof and road are greater than wall, due to shadowing effect. Surface temperature of urban areas is strongly influenced by local buildings configuration. Walls surfaces are less active emiting H at night for the h/w increasingly large. H emission from road surface decreases with increasing h/w. Increasing breadth of walls surfaces causing L↓ trapped in the canyon becomes higher, thus canyon temperatures remain high.

The CT Scan is the most significant contributor to radiation dose on radiological examination, although the frequency of the examination is far below other modalities. In order to control this radiation dose, manufactures of CT Scan have equipped their units with built-in software called Automatic Exposure Control (AEC). This study aims to analyze the effect of AEC software, CARE Dose 4D, on image quality, and CTDIvol. Objects used in this study were three water phantoms, each with a diameter of 165 mm, 230 mm, and 305 mm. The image quality-analyzed was CT Number and noise. Measurement of image quality was carried out following Bapeten's provisions. Noise Power Spectrum (NPS) graphics were also used to further observes noise texture. The CT Number accuracy, CT Number, and noise uniformity obtained with and without CARE Dose 4D, on the three phantoms were still within Bapeten's threshold. This indicates that the use of CARE Dose 4D can still image a homogeneous object accurately. The results of the NPS curve showed that the two modes, in three phantoms, were having the same noise texture. The NPS curves also showed that the use of CARE Dose 4D produces higher noise than the non-CARE Dose 4D mode. Meanwhile, there were significant differences from the CTDIvol obtained from the two modes. The use of CARE Dose 4D software reduced dose of up to 54.34%. From this, the use of CARE Dose 4D software can reduce the radiation dose while maintaining image quality.