Approximate electromagnetic cloaking of a conducting cylinder using homogeneous isotropic multi-layered materials

AbstractCloaking refers to hiding a body from detection by surrounding it with a coating consisting of an unusual anisotropic nonhomogeneous material. Its function is to deflect the rays that would have struck the object, guide them around the object, and return them to their original trajectory, thus no waves are scattered from the body. The permittivity and permeability of such a cloak are determined by the coordinate transformation of compressing a hidden body into a point or a line. Some components of the electrical parameters of the cloaking material (ɛ, μ) are required to have infinite or zero value at the boundary of the hidden object. Approximate cloaking can be achieved by transforming the cylindrical body (dielectric and conducting) virtually into a small cylinder rather than a line, which eliminates the zero or infinite values of the electrical parameters. The radially-dependent cylindrical cloaking shell can be approximately discretized into many homogeneous anisotropic layers; each anisotropic layer can be replaced by a pair of equivalent isotropic sub-layers, where the effective medium approximation is used to find the parameters of these two equivalent sub-layers. In this work, the scattering properties of cloaked perfectly conducting cylinder is investigated using a combination of approximate cloaking, together with discretizing the cloaking material using pairs of homogeneous isotropic sub-layers. The solution is obtained by rigorously solving Maxwell equations using angular harmonics expansion. The scattering pattern, and the back scattering cross section against the frequency are studied for both transverse magnetic (TMz) and transverse electric (TEz) polarizations of the incident plane wave for different transformed body radii

Workplace-Related Traumatic Injuries: Insights from a Rapidly Developing Middle Eastern Country

Traumatic workplace-related injuries (WRIs) carry a substantial negative impact on the public health worldwide. We aimed to study the incidence and outcomes of WRIs in Qatar. We conducted occupational injury surveillance for all WRI patients between 2010 and 2012. A total of 5152 patients were admitted to the level 1 trauma unit in Qatar, of which 1496 (29%) sustained WRI with a mean age of 34.3±10.3. Fall from height (FFH) (51%) followed by being struck by heavy objects (FHO) (18%) and motor vehicle crashes (MVC) (17%) was the commonest mechanism of injury (MOI). WRI patients were mainly laborers involved in industrial work (43%), transportation (18%), installation/repair (12%), carpentry (9%), and housekeeping (3%). Use of protective device was not observed in 64% of cases. The mean ISS was 11.7±8.9, median ICU stay was 3 days (1–64), and total hospital stay was 6 days (1–192). The overall case fatality was 3.7%. Although the incidence of WRI in Qatar is quite substantial, its mortality rate is relatively low in comparison to other countries of similar socioeconomic status. Prolonged hospital stay and treatment exert a significant socioeconomic burden on the nation’s and families’ resources. Focused and efficient injury prevention strategies are mandatory to prevent future WRI

Rollover Car Crashes with Ejection: A Deadly Combination—An Analysis of 719 Patients

Rollover car crashes (ROCs) are serious public safety concerns worldwide. Objective. To determine the incidence and outcomes of ROCs with or without ejection of occupants in the State of Qatar. Methods. A retrospective study of all patients involved in ROCs admitted to Level I trauma center in Qatar (2011-2012). Patients were divided into Group I (ROC with ejection) and Group II (ROC without ejection). Results. A total of 719 patients were evaluated (237 in Group I and 482 in Group II). The mean age in Group I was lower than in Group II (24.3±10.3 versus 29±12.2; P=0.001). Group I had higher injury severity score and sustained significantly more head, chest, and abdominal injuries in comparison to Group II. The mortality rate was higher in Group I (25% versus 7%; P=0.001). Group I patients required higher ICU admission rate (P=0.001). Patients in Group I had a 5-fold increased risk for age-adjusted mortality (OR 5.43; 95% CI 3.11–9.49), P=0.001). Conclusion. ROCs with ejection are associated with higher rate of morbidity and mortality compared to ROCs without ejection. As an increased number of young Qatari males sustain ROCs with ejection, these findings highlight the need for research-based injury prevention initiatives in the country

The therapeutic challenges of degloving soft-tissue injuries

Background: Degloving soft-tissue injuries are serious and debilitating conditions. Deciding on the most appropriate treatment is often difficult. However, their impact on patients′ outcomes is frequently underestimated. Objectives: We aimed to study the incidence, clinical presentation, management and outcome of degloving soft-tissue injuries. Materials and Methods: We conducted a narrative traditional review using the key words; "degloving injury" and "soft-tissue injuries" through search engines PubMed, Science Direct, and Scopus. Results: There are several therapeutic options for treating degloving soft-tissue injuries; however, no evidence-based guidelines have been published on how to manage degloving soft-tissue injuries, although numerous articles outline the management of such injuries. Conclusion: Degloving soft-tissue injuries are underreported and potentially devastating. They require early recognition, and early management. A multidisciplinary approach is usually needed to ensure the effective rehabilitation of these patients

Traumatic injury among females: does gender matter?

BACKGROUND:Trauma remains one of the leading causes of morbidity and mortality worldwide. Generally, the incidence of traumatic injuries is disproportionately high in males. However, trauma in females is underreported.AIM:To study the epidemiology and outcome of different mechanisms and types of traumatic injuries in women.METHODS:We conducted a traditional narrative review using PubMed, MEDLINE and EMBASE, searching for English-language publications for gender-specific trauma between January 1993 and January 2013 using key words "trauma", "gender", "female" and "women".RESULTS:Among 1150 retrieved articles, 71 articles were relevant over 20 years. Although it is an important public health problem, traumatic injuries among females remain under-reported.CONCLUSION:There is a need for further research and evaluation of the exact burden of traumatic injuries among females together with the implementation of effective community based preventive programs.This item is part of the UA Faculty Publications collection. For more information this item or other items in the UA Campus Repository, contact the University of Arizona Libraries at [email protected]