Threshold switching in nickel-doped zinc oxide based memristor for artificial sensory applications.

Electronic devices featuring biomimetic behaviour as electronic synapses and neurons have motivated the emergence of a new era in information and humanoid robotics technologies. In the human body, a nociceptor is a unique sensory neuron receptor that is capable of detecting harmful signals, leading to the central nervous system initiating a motor response. Herein, a nickel-doped zinc oxide (NZO)/Au based memristor is fabricated for the first time and characterized for artificial nociceptor application. For this, the introduction of a nickel-doped zinc oxide (NZO) layer between P++-Si and Au electrodes is used to eliminate the surface effects of the NZO layer, resulting in improved volatile threshold switching performance. Depending on the intensity, duration, and repetition rate of the external stimuli, this newly created memristor exhibits various critical nociceptive functions, including threshold, relaxation, allodynia, and hyperalgesia. The electron trapping/detrapping to/from the traps in the NZO layer is responsible for these nociceptive properties. This kind of NZO-based device produces a multifunctional nociceptor performance that is essential for applications in artificial intelligence systems, such as neural integrated devices with nanometer-sized features.

A survey on radiation protection awareness at various hospitals in Karachi, Pakistan.

Purpose: To assess the awareness level of radiation protection among the radiation workers (i.e. medical radiation technologists, medical physicists, and medical radiological professionals) at the selected radiology, nuclear medicine, and radiotherapy facilities in Karachi, Pakistan. Material and methods: This survey was carried out in Karachi which has the largest number of hospitals, including radiology, nuclear medicine, and radiotherapy facilities in all Pakistan. In this double-blind survey, a questionnaire was designed and distributed to one hundred and sixty five (165) medical radiation workers at their respective workplaces. These radiation workers included the medical radiation technologists, medical physicists, and medical radiological practitioners. These radiation workers had varying experiences, training records, education, and fields of specialization. Out of these total 165 respondents, 84 belonged to the radiology facilities, 20 to nuclear medicine facilities, and 61 to radiotherapy facilities. The educational level was classified as less than 16 years, and equal to or greater than 16 years. Similarly, the training was classified as "attended" or "never attended" and the experience as less than five years, between 5 and 10 years, and greater than ten years. The data was processed through SPSS (v.20) against a significance level (P ≤ 0.05). Results: The statistical analysis of the survey indicates that the radiation workers in radiology, nuclear medicine, and radiotherapy facilities in Karachi have limited awareness of radiation protection issues. The overall outcome of the survey also concluded that the awareness regarding radiation effects, radiation warning signs, and annual dose limit is optimum. However, the response to the questions related to patient protection remained unsatisfactory. Conclusion: This study showed that most of the radiation workers who participated in the survey lacked appropriate awareness of radiation protection measures. The radiation workers did show a better understanding of basic radiation protection parameters, such as the annual dose limit and radiation effects. However, the radiation workers needed an overall improvement in radiation protection awareness, particularly, related to patient protection. This awareness and knowledge should be improved through systematic and periodic trainings.

Measurement of 6 MV small field beam profiles - comparison of micro ionization chamber and linear diode array with monte carlo code.

The objective of this study is to analyze small field photon beams acquired with commonly available detectors. Beam profiles of 6 MV photons from the Siemens Primus Linear Accelerator were measured with a micro ion chamber (IC CC01, IBA) and linear diode array (LDA-99SC, IBA). Data was acquired using a water phantom for small fields (0.5×0.5 cm2 to 4×4 cm2) at depth of maximum dose, 5 cm and 10 cm. Profiles were also generated with EGSnrc Monte Carlo code. Measured and simulated profiles were compared in terms of percentage difference of the area under the simulated and measured profiles (PD), ratio of the measured to simulated dose at the point of maximum deviation within the central region of profile (R), full width half maximum (FWHM) and penumbra. For field sizes ≥1×1 cm2, the maximum PD is 3.17 % and 2.87 % for IC and LDA respectively, whereas R is in the range of 0.95-1.05 for IC and 0.99-1.05 for LDA. LDA measured FWHM and penumbra are also in better agreement with the simulated results. This study demonstrated that LDA can be used for acquisition of beam profiles for field size as low as 1×1 cm2.