Respiratory compensation in projection imaging using a magnification and displacement model

Respiratory motion during the collection of computed tomography (CT) projections generates structured artifacts and a loss of resolution that can render the scans unusable. This motion is problematic in scans of those patients who cannot suspend respiration, such as the very young or intubated patients. Here, the authors present an algorithm that can be used to reduce motion artifacts in CT scans caused by respiration. An approximate model for the effect of respiration is that the object cross section under interrogation experiences time-varying magnification and displacement along two axes. Using this model an exact filtered backprojection algorithm is derived for the case of parallel projections. The result is extended to generate an approximate reconstruction formula for fan-beam projections. Computer simulations and scans of phantoms on a commercial CT scanner validate the new reconstruction algorithms for parallel and fan-beam projections. Significant reduction in respiratory artifacts is demonstrated clinically when the motion model is satisfied. The method can be applied to projection data used in CT, single photon emission computed tomography (SPECT), positron emission tomography (PET), and magnetic resonance imaging (MRI).     

VOC and particulate emissions from commercial cigarettes: analysis of 2,5-DMF as an ETS tracer

Emissions of particulate matter (PM) and a broad suite of target volatile organic compounds (VOCs) in total, main-stream (MS) and side-stream (SS) smoke emissions are measured for six types of commercial cigarettes. The suitability of 2,5-dimethyl furan (DMF) as a tracer for environmental tobacco smoke (ETS) is investigated using laboratory results and a field study of 47 residences. Over 30 VOCs were characterized in cigarette smoke, including several that have not been reported previously. "regular tar", "low tar", menthol, and nonmenthol cigarettes showed only minor differences in PM and VOC emissions. When total emissions are considered, PM emissions averaged 18 +/- 2 mg cigarette(-1) and VOC emissions averaged 3644 +/- 160 mg cigarette(-1). DMF appears to satisfy all requirements for a tracer, namely, uniqueness, detectability, similar emission factors across tobacco products (211 +/- 16 microg cigarette(-1)), consistent proportions to other ETS compounds, and behavior similar to other ETS components in relevant environments. On the basis of field study results, DMF more reliably indicated smoking status than occupant-completed questionnaires, and cigarette smoking was responsible for significant fractions of benzene (50%), styrene (49%), and other VOCs in the smoker's homes.     

The relationship between building characteristics and the chemical composition of surface films found on glass windows in Brisbane,Australia

Films found on the windows of residential buildings have been studied. The main aim of the paper was to assess the roles of the films in the accumulation of potentially toxic chemicals in residential buildings. Thus the elemental and polycyclic aromatic hydrocarbon compositions of the surface films from the glass windows of eighteen residential buildings were examined. The presence of sample amounts of inorganic elements (4.0–1.2 × 10⁶ μg m⁻²) and polycyclic aromatic hydrocarbons in the films (BDL - 620.1 ng m⁻²) has implications for human exposure and the fate of pollutants in the urban environment. To facilitate the interpretation of the results, data matrices consisting of the chemical composition of the films and the building characteristics were subjected to multivariate data analysis methods, and these revealed that the accumulation of the chemicals was strongly dependent on building characteristics such as the type of glass used for the window, the distance from a major road, age of the building, distance from an industrial activity, number of smokers in the building and frequency of cooking in the buildings. Thus, building characteristics which minimize the accumulation of pollutants on the surface films need to be encouraged.     

Housing Policy Changes in Ghana in the 1990s

The housing sector in Ghana has undergone fundamental changes since the 1990s. Policy focus has shifted away from direct state provision and has moved strongly towards active private sector participation in housing production, financing and production of building materials. In part, this is due to the failure of public housing programmes, dwindling state resources, unimpressive performance of state-owned enterprises, and recognition that the government alone is unable to solve the housing problem. On a broader scale, the changes are rooted in liberalization ideologies that have swept through most economies in the 1980s and 1990s, which have had varying effects on people's housing need and on the national economy. The purpose of this paper is to examine these effects, to offer some interpretations, and to outline some of the lingering challenges facing the country's housing sector.     

A compulsator driven rapid-fire EM gun

A compulsator-driven railgun is an attractive alternative to the homopolar generator-inductor-switch configuration, especially for repetitive duty. A conceptual design of a rapid-fire EM-gun system is presented. The generator is sized to accelerate a 0.08-kg projectile to 2 to 3 km/s at a 60 pulse-per-second repetition rate. Initial design parameters are discussed, and example current and velocity waveforms are given. The generator is discharged at the proper phase angle to provide a current zero just as the projectile exits the muzzle of the railgun.     

Comparing ANN and ARIMA model in predicting the discharge of River Opeki from 2010 to 2020

Many attempts have been made in the recent past to model and forecast streamflow using various techniques with the use of time series techniques proving to be the most common. Time series analysis plays an important role in hydrological research. Traditionally, the class of autoregressive moving average techniques models has been the statistical method most widely used for modelling water discharge, but it has been shown to be deficient in representing nonlinear dynamics inherent in the transformation of runoff data. In contrast, the relatively newly improved and efficient soft computing technique artificial neural networks has the capability to approximate virtually any continuous function up to an arbitrary degree of accuracy, which is not otherwise true of other conventional hydrological techniques. This technique corresponds to human neurological system, which consists of a series of basic computing elements called neurons, which are interconnected together to form networks. The aim of the study is to compare the artificial neural network and autoregressive integrated moving average to model River Opeki discharge (1982–2010) and to use the best predictor to forecast the discharge of the river from 2010 to 2020. The performance of the two models was subjected to statistical test based on correlation coefficient (r) and the root‐mean‐square error. The result showed that autoregressive integrated moving average performs better considering the level of root‐mean‐square error and higher correlation coefficient.     

Evolutionary multi criteria design optimization of robot grippers

This paper explores the use of intelligent techniques to obtain optimum geometrical dimensions of a robot gripper. The optimization problem considered is a non-linear, complex, multi-constraint and multicriterion one. Three robot gripper configurations are optimized. The aim is to find Pareto optimal front for a problem that has five objective functions, nine constraints and seven variables. The problem is divided into three cases. Case 1 has first two objective functions, the case 2 considers last three objective functions and case 3 deals all the five objective functions. Intelligent optimization algorithms namely Multi-objective Genetic Algorithm (MOGA), Elitist Non-dominated Sorting Genetic Algorithm (NSGA-II) and Multi-objective Differential Evolution (MODE) are proposed to solve the problem. Normalized weighting objective functions method is used to select the best optimal solution from Pareto optimal front. Two multi-objective performance measures (solution spread measure (SSM) and ratio of non-dominated individuals (RNIs)) are used to evaluate the strength of the Pareto optimal fronts. Two more multi-objective performance measures namely optimizer overhead (OO) and algorithm effort are used to find the computational effort of MOGA, NSGA-II and MODE algorithms. The Pareto optimal fronts and results obtained from various techniques are compared and analyzed.     

An experimental investigation into the response analysis of multistoreyed buildings

Presented are the results of an experimental study on the response forces and damping values of a model of a five storeyed building frame and its five equivalent single degree mode-models during free and forced vibrations on a vibration bed.     

Human Peripheral Blood Mononucleocyte Derived Myeloid Committed Progenitor Cells Mitigate H-ARS by Exosomal Paracrine Signal

Radiation-induced loss of the hematopoietic stem cell progenitor population compromises bone marrow regeneration and development of mature blood cells. Failure to rescue bone marrow functions results in fatal consequences from hematopoietic injury, systemic infections, and sepsis. So far, bone marrow transplant is the only effective option, which partially minimizes radiation-induced hematopoietic toxicities. However, a bone marrow transplant will require HLA matching, which will not be feasible in large casualty settings such as a nuclear accident or an act of terrorism. In this study we demonstrated that human peripheral blood mononuclear cell-derived myeloid committed progenitor cells can mitigate radiation-induced bone marrow toxicity and improve survival in mice. These cells can rescue the recipient’s hematopoietic stem cells from radiation toxicity even when administered up to 24 h after radiation exposure and can be subjected to allogenic transplant without GVHD development. Transplanted cells deliver sEVs enriched with regenerative and immune-modulatory paracrine signals to mitigate radiation-induced hematopoietic toxicity. This provides a natural polypharmacy solution against a complex injury process. In summary, myeloid committed progenitor cells can be prepared from blood cells as an off-the-shelf alternative to invasive bone marrow harvesting and can be administered in an allogenic setting to mitigate hematopoietic acute radiation syndrome.