Results of lidar modeling based on spatial-angular filtering efficiency criteria are presented. Their analysis shows that the low spatial-angular filtering efficiency of traditional visible and near-infrared systems is an important cause of low signal/background-radiation ratio (SBR) at the photodetector input The low SBR may be responsible for considerable measurement errors and ensuing the lo...

The combination of detections of anisotropy in cosmic microwave background radiation and observations of the large-scale distribution of galaxies probes the primordial density fluctuations of the universe on spatial scales varying by three orders of magnitude. These data are found to be inconsistent with the predictions of several popular cosmological models. Agreement between the data and the ...

Potential biological damage from radiation received during fluoroscopy procedures is of particular concern because of the high volume and variety of procedures performed and the increasing length of radiation exposure. This article focuses on the effects of low-level radiation, gaps in education and skills among personnel performing and assisting with fluoroscopy, the certification and privileg...

An increase in radiation dose exposure In 2006, the average annual effective dose per individual in the US was 6.2 mSv1, a figure that has almost doubled over the last 25 years [1]. Approximately 50% of the dose currently received stems from background radiation [1], but varies depending on where you live (for example, in Australia dose levels are about half of levels in the US) [2]. The other ...

The in situ measured average outdoor absorbed dose rate in air was found to vary from 108.4 to 1596.4 nGy h at Homa Mountain area in southwestern Kenya. Rock and soil samples collected gave average values of the radioactivity concentrations of K, Ra and Th of 915.6, 195.3 and 409.5 Bq kg, respectively. The range of the annual effective dose for a person living in Homa Mountain area calculated v...

OBJECTIVE To compare the total work-related radiation dose in our department of radiology with the dose in Dutch residences, taking x-ray radiation, external natural radiation and radon into account. METHODS Annual doses due to exposure to x-rays and external natural radiation were derived from the measured personal dose equivalent [H(p)(10)] of 144 workers. Additionally, departmental (222)Rn...

We experimentally demonstrate ultrafast polarization switching of terahertz (THz) radiation generated by dual-color driving pulses composed of orthogonally polarized fundamental and second-harmonic waves, which can be controlled by field-free molecular alignment in air by modulating the relative phase between the two field components as a transient dynamic wave plate. By fine-tuning the time de...