[en] This text introduces the inexperienced individual to some of the basics in procuring and interpreting the common lateral cephalometric radiograph and its importance in clinical application

No abstract available

[en] An interferometer described in the Boston, 1992, meeting of the Beacon Satellite Symposium has been in full operation for over a year now. It consists of four autonomous stations; three are in a triangle 70 km on a side and one is in the center. The stations receive the VHF beacons from two geosynchronous satellites, GOES-2 and ATS-3. The phases of the beacons are tracked at each station by referring them to an extremely stable rubidium oscillator. The studies of the two satellites are virtually separate experiments. The received phase of the beacon is retarded by the increased Total-Electron-Content of the dense regions of waves in the ionosphere. By comparing the phase history at four spatially separated stations, the authors can determine the two-dimensional propagation vector of the waves. This array is optimal for wavelengths of 70--300 km (periods of 300--3,000 seconds). Since the measurement is of the phase of the signal rather than the difference between the O-mode and X-mode phases, and since the beacons are in the VHF rather than in the L-band of GPS beacons, the array is very sensitive. It has a noise level of 10¹³ electrons/m², or 10^-4 of the normal daytime TEC. This has been verified by operating two stations in the same location, so that they saw the same ionosphere. The first interesting results from a year's study is that the authors do not see the same TID's when looking at the two satellites. One conclusion they draw is that they do not see evidence of ionospheric winds

[en] Concern for higher radiation levels associated with some of the latest generation computed tomography (CT) scanners points to the need for dissemination of meaningful quantitative radiation dose data about these improved imaging units. Recent radiation protection survey data of some new CT installations are offered. Knowledgeable use of such information should afford CT users a basis for proper use of this valuable imaging modality within current radiation protection guidelines

No abstract available

[en] The estimation of fetal dose incurred by patients undergoing various radiologic procedures can be very perplexing. The problem is especially critical for women who do not know that they are pregnant at the time of x-ray exposure. A description is offered of efforts to quantitate the fetal dose by after-the-fact calculations. Such conservatively employed calculations may be essential for a clinical decision regarding therapeutic abortion

[en] In the course of our investigation aimed at the preparation of homochiral coordination polymers using readily available in optically pure form ligands and building blocks of condensed metal polyhedra, we recently reported a one-dimensional nickel aspartate compound [Ni₂O(L-Asp)(H₂O)₂]·4H₂O (1) based on helical chains with extended Ni-O-Ni bonding. Here we report a new nickel aspartate [Ni_2.5(OH)(L-Asp)₂]·6.55H₂O (2) with a three-dimensional Ni-O-Ni connectivity that forms at a higher pH and is based on the same helices as in 1 which are connected by additional nickel octahedra to generate a chiral open framework with one-dimensional channels with minimum van der Waals dimensions of 8 x 5 Angstroms. The crystal structure of 2 was determined by synchrotron single-crystal X-ray diffraction on a 10 x 10 x 240 (micro)m crystal

[en] Market-based rural electrification with solar energy is increasingly common in developing countries. This article revolves around three main claims about solar electrification in Kenya's unsubsidized market: (1) The benefits of solar electrification are captured primarily by the rural middle class. (2) Solar electricity plays a modest role in supporting economically productive and education-related activities, but 'connective' applications such as television, radio, and cellular telephone charging often receive a higher priority. (3) Solar electrification is more closely tied to increased television use, the expansion of markets, more rural-urban communication, and other processes that increase rural-urban connectivity than to poverty alleviation, sustainable development, or the appropriate technology movement. [Author]

[en] Short communication

[en] An accidental over-exposure to an ¹⁹²Ir industrial radiography source is described. Dose estimation efforts and clinical evaluation of radiation injury are included in this description. Several meaningful recommendations are offered with a view toward improving industrial radiography radiation safety. (author)