A new model for broadband waveguide to microstrip transition design

A new model is presented which permits the prediction of the resonant frequencies created by antipodal finline waveguide to microstrip transitions. The transition is modeled as a tapered transmission line in series with an infinite set of coupled resonant circuits. The resonant circuits are modeled as simple microwave resonant cavities of which the resonant frequencies are easily determined. The model is developed and the resonant frequencies determined for several different transitions. Experimental results are given to confirm the models

Induction......

Inductive Reasonin

A Tailored Systems Engineering Process for the Development of CubeSat Class Satellites

The class of small satellites known as CubeSats have grown in popularity and complexity in recent years and have been especially popular with colleges and universities interested in utilizing them both for their value as an educational tool and to conduct science missions. While there have been some tremendously successful CubeSat missions over the years, those that are launched are still more likely than not to be dead on arrival or to fail before accomplishing their objectives. Part of this low success rate, especially of student built CubeSats, may be attributed to the fact that they are often designed in an ad hoc manner, with students working on projects for only a fixed period of time and without a view of the big picture. In contrast, large space-focused organizations utilize Systems Engineering (SE) to standardize processes and improve the odds of mission success. The National Aeronautics and Space Administration (NASA) uses their own SE methodology and it is so complex that the process overview, known as the NASA Project Life Cycle Process Flow can take up an entire wall when printed in full size. While it may not be feasible to apply such a complex SE methodology to most CubeSat developments, they could be improved a great deal by utilizing a rigorous but tailored process of their own. Specifically, CubeSat developers should focus on requirements definition and flow-down, risk analysis and mitigation, cost and schedule management, and integration and interface management. These areas would be aided significantly by developing artifacts such as a Cost Analysis, Risk Analysis, Test and Evaluation Plan, Model Based Architecture, and a Concept of Operations. This paper describes work which aims to develop and implement an optimized SE process for CubeSats intended specifically for student-run projects taking place over the course of a single academic year. It will be implemented on a student CubeSat project at the United States Naval Academy (USNA) and validated by comparing key performance parameters of their project to those of other similar CubeSats developed without using this process. The result of this study will be a tailored SE process that can be applied to virtually any student CubeSat project to improve performance and importantly to increase the chances of mission success

Image Analysis Techniques for the Automated Evaluation of Subaxial Subluxation in Cervical Spine X-Ray Images

Rheumatoid arthritis is a chronic inflammatory disease affecting synovial joints of the body, especially the hands and feet, spine, knees and hips. For many patients, the cervical spine is associated with rheumatoid arthritis. Subluxation is the abnormal movement of one of the bones that comprise a joint. In this research, image analysis techniques have been investigated for the recognition of cervical spine x-ray images with one or more instances of subaxial subluxation. Receiver operating characteristic curve results are presented, showing potential for subaxial subluxation discrimination on an image-by-image basis

Survival analysis of metal crowns versus restorations in primary mandibular molars

Background The effectiveness of stainless steel crowns (SSCs) versus direct restorations when placed in primary mandibular molars (teeth nos. L and S) is uncertain. The authors evaluated effectiveness by gauging longevity of treatment. Methods The authors obtained private dental insurance claims (2004-2016) from a national dental data warehouse. Paid insurance claims records (n = 1,323,489) included type of treating dentist, treatment placed, and patient age. Results Dentist specialty, type of treatment, and patient age were significant in predicting failure after the first restoration. The authors found high survival rates for all treatments (> 90%) after 5 years; however, as soon as within 3 years after treatment, SCCs had approximately 6% better survival. Conclusions Teeth nos. L and S first treated with SSCs lasted longer without new treatment compared with teeth first treated with direct restorations; the difference was small. Teeth treated by pediatric dentists had better survival rates. Practical Implications Primary mandibular first molars initially treated with SSCs lasted longer without new treatment compared with direct restorations. Overall dental care costs of the former were considerably higher

Trends in dental insurance claims in the United States before and during the SARS-CoV-2 pandemic in 2020

Objectives: The SARS-CoV-2 pandemic disrupted health care services. Previous reports estimated reductions in demand and supply of dental care services, but actual changes have not been reported. The present report depicts a perspective of trends in claims from private dental practice in the United States during 2019 and 2020. Methods: Private dental insurance paid claims data from a data warehouse (encompassing 66+ carriers in the United States) were obtained for children and adults (treatments identified by their American Dental Association Code of Dental Procedures and Nomenclature [CDT]), encompassing a 5% random sample of all records between January 2019 and December 2020. A market-based treatment classification placed CDT codes into one of four categories based on the likelihood of being associated with urgent/emergency care. Results: Claims for 3.8 million patients constituted the 5% random sample for analyses. Substantial drops in the provision of treatment items were quantified for a large segment of private dental insurance plans at a national level, showing differential impacts in dental care categories. Conclusions: Week-by-week, detailed descriptions of demand/availability changes in dental care throughout the first year of the 2020 SARS-CoV-2 pandemic were obtained through contrasting perspectives in 2019. Provision of dental care and associated impacts fluctuated over time subject to treatment urgency, but also modified as the weeks/months of dental office lockdowns ebbed in and out of the dental market

Parathyroid hormone related peptide and receptor expression in paired primary prostate cancer and bone metastases

Parathyroid hormone-related peptide is a regulatory protein implicated in the pathogenesis of bone metastases, particularly in breast carcinoma. Parathyroid hormone-related peptide is widely expressed in primary prostate cancers but there are few reports of its expression in prostatic metastases. The aim of this study was to examine the expression of parathyroid hormone-related peptide and its receptor in matched primary and in bone metastatic tissue from patients with untreated adenocarcinoma of the prostate. Eight-millimetre trephine iliac crest bone biopsies containing metastatic prostate cancer were obtained from 14 patients from whom matched primary tumour tissue was also available. Histological grading was performed by an independent pathologist. The cellular location of mRNA for parathyroid hormone-related peptide and parathyroid hormone-related peptide receptor was identified using in situ hybridization with 35S-labelled probe. Expression of parathyroid hormone-related peptide and its receptor was described as uniform, heterogenous or negative within the tumour cell population. Parathyroid hormone-related peptide expression was positive in 13 out of 14 primary tumours and in all 14 metastases. Receptor expression was evident in all 14 primaries and 12 out of 14 metastases. Co-expression of parathyroid hormone-related peptide and parathyroid hormone-related peptide receptor was common (13 primary tumours, 12 metastases). The co-expression of parathyroid hormone-related peptide and its receptor suggest that autocrine parathyroid hormone-related peptide mediated stimulation may be a mechanism of escape from normal growth regulatory pathways. The high frequency of parathyroid hormone-related peptide expression in metastases is consistent with a role in the pathogenesis of bone metastases

Utilization of Stainless Steel Crowns by Pediatric and General Dentists

Purpose: Dental caries affects 23% of US children aged two to five 1. Extensive caries in children should be treated with stainless steel crowns (SSC); however, disparity exists between pediatric and general dentists in restoration type provided. The purpose of the study was to evaluate utilization of SSCs by pediatric and general dentists through insurance claims. Methods: Data was obtained from a commercial dental insurance claims data warehouse from more than 50 dental insurance plans and multiple carriers in the U.S. A generalized linear mixed effects model tested differences in the utilization of SSCs by the general dentist versus the pediatric dentist. Results: The data included 107,487 general dentists and 5,395 pediatric dentists. The records included 2,555,726 claims for restorations and 440,423 claims for the SSC. Pediatric dentists are more likely to place SSCs compared to the general dentist. The tooth most often to receive a SSC was a primary second molar. The majority of SSCs were placed in children aged six years old. Conclusions: Pediatric dentists are more likely to restore carious primary dentition with SSCs compared to general dentists. Perhaps increasing training at the dental undergraduate level would increase the utilization of SSCs