Is body weight the most appropriate criterion to select patients eligible for low-dose pulmonary CT angiography? Analysis of objective and subjective image quality at 80 kVp in 100 patients

The objective of this retrospective study was to assess image quality with pulmonary CT angiography (CTA) using 80 kVp and to find anthropomorphic parameters other than body weight (BW) to serve as selection criteria for low-dose CTA. Attenuation in the pulmonary arteries, anteroposterior and lateral diameters, cross-sectional area and soft-tissue thickness of the chest were measured in 100 consecutive patients weighing less than 100 kg with 80 kVp pulmonary CTA. Body surface area (BSA) and contrast-to-noise ratios (CNR) were calculated. Three radiologists analyzed arterial enhancement, noise, and image quality. Image parameters between patients grouped by BW (group 1: 0-50 kg; groups 2-6: 51-100 kg, decadally increasing) were compared. CNR was higher in patients weighing less than 60 kg than in the BW groups 71-99 kg (P between 0.025 and <0.001). Subjective ranking of enhancement (P = 0.165-0.605), noise (P = 0.063), and image quality (P = 0.079) did not differ significantly across all patient groups. CNR correlated moderately strongly with weight (R = -0.585), BSA (R = -0.582), cross-sectional area (R = -0.544), and anteroposterior diameter of the chest (R = -0.457; P < 0.001 all parameters). We conclude that 80 kVp pulmonary CTA permits diagnostic image quality in patients weighing up to 100 kg. Body weight is a suitable criterion to select patients for low-dose pulmonary CTA.

A generalized anisotropic quadric yield criterion and its application to bone tissue at multiple length scales

Nonlinear computational analysis of materials showing elasto-plasticity or damage relies on knowledge of their yield behavior and strengths under complex stress states. In this work, a generalized anisotropic quadric yield criterion is proposed that is homogeneous of degree one and takes a convex quadric shape with a smooth transition from ellipsoidal to cylindrical or conical surfaces. If in the case of material identification, the shape of the yield function is not known a priori, a minimization using the quadric criterion will result in the optimal shape among the convex quadrics. The convexity limits of the criterion and the transition points between the different shapes are identified. Several special cases of the criterion for distinct material symmetries such as isotropy, cubic symmetry, fabric-based orthotropy and general orthotropy are presented and discussed. The generality of the formulation is demonstrated by showing its degeneration to several classical yield surfaces like the von Mises, Drucker–Prager, Tsai–Wu, Liu, generalized Hill and classical Hill criteria under appropriate conditions. Applicability of the formulation for micromechanical analyses was shown by transformation of a criterion for porous cohesive-frictional materials by Maghous et al. In order to demonstrate the advantages of the generalized formulation, bone is chosen as an example material, since it features yield envelopes with different shapes depending on the considered length scale. A fabric- and density-based quadric criterion for the description of homogenized material behavior of trabecular bone is identified from uniaxial, multiaxial and torsional experimental data. Also, a fabric- and density-based Tsai–Wu yield criterion for homogenized trabecular bone from in silico data is converted to an equivalent quadric criterion by introduction of a transformation of the interaction parameters. Finally, a quadric yield criterion for lamellar bone at the microscale is identified from a nanoindentation study reported in the literature, thus demonstrating the applicability of the generalized formulation to the description of the yield envelope of bone at multiple length scales.

Targeting Families to Receive Intensive Family Preservation Services: Assessing the Use of Imminent Risk of Placement as a Service Criterion

The process for targeting families to receive intensive family preservation services was examined for 71 child welfare agencies in the United States. The focus of this exploratory/descriptive study was the concept of imminent risk of placement as a criterion for providing services. Findings indicated that agencies had difficulty defining imminent risk and were unable to successfully restrict services to imminent risk cases. Several factors besides imminent risk were identified in relation to the targeting process.

Development and Criterion Validity of Differentiated and Elevated Vocational Interests in Adolescence

Interest differentiation and elevation are supposed to provide important information about a person’s state of interest development, yet little is known about their development and criterion validity. The present study explored these constructs among a group of Swiss adolescents. Study 1 applied a cross-sectional design with 210 students in 11th grade. Study 2 applied a 1-year longitudinal design with 289 students in 7th to 8th grade. gender, personality traits, and career exploration were significant predictors of state and development of differentiation and elevation. Increase in differentiation predicted increase in career decidedness above traits. elevation could not predict increase in exploration behavior over traits. The results provide support for differentiation and elevation as important aspects of adolescents’ vocational interests.

The Dental School Applicant Pool and the Oral Healthcare Workforce

One of the major challenges faced by the dental profession today is the recruitment of the most qualified dental school applicants who are capable of serving the nation’s future oral healthcare needs. The Association of Schools of Public Health (ASPH) also recognizes this challenge, describing one of the three core functions of public health as “assuring that all populations have access to appropriate and cost effective care, including health promotion and disease prevention services.” To achieve this core function, the ASPH cites “a competent public health and personal healthcare workforce” as one of the ten essential public health services. Unfortunately, the goals of both quality and equality in terms of the dental workforce and access to oral healthcare have yet to be realized. When considering access to oral health services on a national or state level, a thoughtful and thorough consideration of the dental school applicant pool is essential. According to a recent study published in the Journal of the American Dental Association, the annual number of retiring dentists will exceed the number of newly licensed dental practitioners in 2009, a trend which is projected to continue throughout the next decade. The approximately 4,400 dentists produced each year from the nation’s 57 accredited dental education programs are charged with the responsibility of meeting the oral healthcare needs of the population at large.

On the Mahalanobis Distance Classification Criterion for Multidimensional Normal Distributions

Many existing engineering works model the statistical characteristics of the entities under study as normal distributions. These models are eventually used for decision making, requiring in practice the definition of the classification region corresponding to the desired confidence level. Surprisingly enough, however, a great amount of computer vision works using multidimensional normal models leave unspecified or fail to establish correct confidence regions due to misconceptions on the features of Gaussian functions or to wrong analogies with the unidimensional case. The resulting regions incur in deviations that can be unacceptable in high-dimensional models. Here we provide a comprehensive derivation of the optimal confidence regions for multivariate normal distributions of arbitrary dimensionality. To this end, firstly we derive the condition for region optimality of general continuous multidimensional distributions, and then we apply it to the widespread case of the normal probability density function. The obtained results are used to analyze the confidence error incurred by previous works related to vision research, showing that deviations caused by wrong regions may turn into unacceptable as dimensionality increases. To support the theoretical analysis, a quantitative example in the context of moving object detection by means of background modeling is given.

A general stability criterion for switched linear systems having stable and unstable subsystems

We report conditions on a switching signal that guarantee that solutions of a switched linear systems converge asymptotically to zero. These conditions are apply to continuous, discrete-time and hybrid switched linear systems, both those having stable subsystems and mixtures of stable and unstable subsystems.