K-Space Aware Multi-Static Millimeter-Wave Imaging.

This paper focuses on an ef?cient approach of designing multi-static arrays for millimeter-wave imaging, based on the k-space or Fourier-spatial domain characteristic of imaging systems. Our goal is to decrease the redundancy of the data measured by each antenna, and to improve the resolution of the reconstructed image. The proposed technique is based on determining the role of each transmitter and receiver, in collecting the data from each voxel of the target in k-space domain and then rotating transmitters' beams to measure the desirable information. The effect of non-uniform redundant k-space domain frequency samples that act as an undesirable ?lter, is compensated using a modi?ed SAR back-projection algorithm. Experimental and simulation results are presented and compared with that of a sparse multi-static array with the same number of transmitters and receivers. Our simulations and measurements show signi?cant improvement in terms of overall quality and edge preservation in the reconstructed images. Also, the obtained results demonstrate that using the proposed structure and algorithm, the average improvement in peak-signalto-noise ratio (PSNR), structural similarity index measure (SSIM) and digital image correlation (DIC) metrics of 3.03 dB, 0.22 and 0.173, are achieved, respectively.

A Successful implementation of an idea to a nationally approved plan: Analyzing Iran's National Health Roadmap using the Kingdon model of policymaking.

Introduction: Hospital beds, human resources, and medical equipment are the costliest elements in the health system and play an essential role at the time of treatment. In this paper, different phases of the NEDA 2026 project and its methodological approach were presented and its formulation process was analysed using the Kingdon model of policymaking. Methods: Iran Health Roadmap (NEDA 2026) project started in March 2016 and ended in March 2017. The main components of this project were hospital beds, clinical human resources, specialist personnel, capital medical equipment, laboratory facilities, emergency services, and service delivery model. Kingdon model of policymaking was used to evaluate NEDA 2026 development and implementation. In this study, all activities to accomplish each step in the Kingdon model was described. Results: The followings were done to accomplish the goals of each step: collecting experts' viewpoint (problem identification and definition), systematic review of the literature, analysis of previous experiences, stakeholder analysis, economic analysis, and feasibility study (solution appropriateness analysis), three-round Delphi survey (policy survey and scrutinization), and intersectoral and interasectoral agreement (policy legislation). Conclusion: In the provision of an efficient health service, various components affect each other and the desired outcome, so they need to be considered as parts of an integrated system in developing a roadmap for the health system. Thus, this study demonstrated the cooperation process at different levels of Iran's health system to formulate a roadmap to provide the necessary resources for the health sector for the next 10 years and to ensure its feasibility using the Kingdon policy framework.

Clinician-generated torque on abutment screws using different hand screwdrivers.

STATEMENT OF PROBLEM: Many clinicians use hand screwdrivers to tighten prosthetic and abutment screws. The impact of the screwdriver type, the location of the implant, and the sex of the practitioner on the generated torque is not well understood. PURPOSE: The purpose of this in vitro study was to compare the torque generated by different hand screwdrivers when used in the anterior and posterior regions and to evaluate the correlation between the applied torque and the sex and body mass index (BMI) of the practitioner. MATERIAL AND METHODS: A mandibular typodont with anterior and posterior implants was mounted in a mannequin head. Fifty clinicians (6 prosthodontists, 8 graduate prosthodontic students, and 36 dental students) used their maximum force to tighten the abutment screws in the anterior and posterior regions, using 3 different hand screwdrivers, with handles of different shapes and sizes (small, medium, and large). The torque values generated were measured using torque meters connected to the implants. The generated torque, sex, age, height, and weight were also recorded for each clinician. A generalized linear model was used to find correlations between the different factors and the generated torque (α=.05). RESULTS: Significant differences were observed among the applied torque values when different screwdrivers were used (P<.001). Higher torque values were generated in the anterior region than in the posterior region (P<.001). The interaction of the sex and BMI of the participants significantly affected the generated torque values (P=.044). CONCLUSIONS: The type of screwdriver and location of the implant affected the generated torque. Torque values generated by the large screwdriver were higher than those of small and medium screwdrivers. Higher torque was applied in the anterior region.

Active tactile sensibility of single-tooth implants versus natural dentition: a split-mouth double-blind randomized clinical trial.

BACKGROUND: Unlike passive sensitivity of implants/teeth that is assessed more, only three controversial studies have compared active tactile sensibility (ATS) of implants and teeth. PURPOSE: We aimed to explore the difference between the ATS of teeth and single-tooth implants. METHODS: The ATS of single-tooth implants and contralateral teeth was measured in 25 patients after they bit on gold and placebo foils 0- to 70-µm thick, each for five times, in a random order blinded to patients and assessor, carried out at two sessions. Based on the experimental range of 0 µm (mock trials) to 70 µm, the sigmoid shape of psychometric curve was estimated to locate the 50% values as the ATS thresholds for each tooth or implant. ATS Data were analyzed using paired and unpaired t-tests and multiple linear regression (α = 0.05, ß ≤ 0.1). Also, equivalence testing approach was used to assess semi-objectively the clinical significance. RESULTS: Average ATS values for teeth and implants were 21.4 ± 6.55 µm and 30.0 ± 7.55 µm, respectively (p = .0001 [paired t-test]). None of the geometric characteristics of implants nor duration of implant in function were correlated with the ATS (p > .4 [regression]). Age was positively associated with the ATS of both implants and teeth (p ≤ .019 [regression]). Tooth ATS (but not implant ATS) was significantly higher in males compared with females (p = .050 [unpaired t-test]), which contributed to a generalizable tooth-implant difference higher than 8-µm clinical equivalence margin in females. The ATS was not significantly different between arches or between anterior/posterior regions (p > .6). CONCLUSION: There was a slight but statistically significant difference between implant and tooth tactile sensitivities.