Recent trends, technical concepts and components of computer-assisted orthopedic surgery systems: A comprehensive review

Computer-assisted orthopedic surgery (CAOS) systems have become one of the most important and challenging types of system in clinical orthopedics, as they enable precise treatment of musculoskeletal diseases, employing modern clinical navigation systems and surgical tools. This paper brings a comprehensive review of recent trends and possibilities of CAOS systems. There are three types of the surgical planning systems, including: systems based on the volumetric images (computer tomography (CT), magnetic resonance imaging (MRI) or ultrasound images), further systems utilize either 2D or 3D fluoroscopic images, and the last one utilizes the kinetic information about the joints and morphological information about the target bones. This complex review is focused on three fundamental aspects of CAOS systems: their essential components, types of CAOS systems, and mechanical tools used in CAOS systems. In this review, we also outline the possibilities for using ultrasound computer-assisted orthopedic surgery (UCAOS) systems as an alternative to conventionally used CAOS systems.Web of Science1923art. no. 519

La teoría del caos y sus problemas epistemológicos

El objetivo del presente trabajo es contribuir a la discusión epistemológica acerca de la Teoría del Caos. Nos concentramos en el problema de la definición de caos, argumentando que impredictibilidad y aleatoriedad algorítmica no constituyen una base satisfactoria para definir el caos. El análisis de las diferentes manifestaciones del caos nos permite considerar el problema de encontrar una definición de caos única y adecuada -una definición que brinde condiciones necesarias y suficientes válidas para todas los casos. Sostenemos que, dado el carácter matemático de la temía, la definición debe extraerse a partir de las características de las ecuaciones caóticas

Hysteresis and bi-stability by an interplay of calcium oscillations and action potential firing

Many cell types exhibit oscillatory activity, such as repetitive action potential firing due to the Hodgkin-Huxley dynamics of ion channels in the cell membrane or reveal intracellular inositol triphosphate (IP$_3$) mediated calcium oscillations (CaOs) by calcium-induced calcium release channels (IP$_3$-receptor) in the membrane of the endoplasmic reticulum (ER). The dynamics of the excitable membrane and that of the IP$_3$-mediated CaOs have been the subject of many studies. However, the interaction between the excitable cell membrane and IP$_3$-mediated CaOs, which are coupled by cytosolic calcium which affects the dynamics of both, has not been studied. This study for the first time applied stability analysis to investigate the dynamic behavior of a model, which includes both an excitable membrane and an intracellular IP$_3$-mediated calcium oscillator. Taking the IP$_3$ concentration as a control parameter, the model exhibits a novel rich spectrum of stable and unstable states with hysteresis. The four stable states of the model correspond in detail to previously reported growth-state dependent states of the membrane potential of normal rat kidney fibroblasts in cell culture. The hysteresis is most pronounced for experimentally observed parameter values of the model, suggesting a functional importance of hysteresis. This study shows that the four growth-dependent cell states may not reflect the behavior of cells that have differentiated into different cell types with different properties, but simply reflect four different states of a single cell type, that is characterized by a single model.Comment: 29 pages, 6 figure

Perceptions of Illinois Community College Chief Academic Officers: Fulfilling the Mission

This study documents voices of the most experienced active Illinois community college chief academic officers (CAOs). Adaptive leadership theory is used to frame the effort of CAOs to infuse accountability into the core community college open access mission. The analysis of conversations with these CAOs reveals a focus on accountability that centers around student success initiatives rather than an urgent need to improve completion rate. The CAOs interviewed perceived student success and open access as crucial components of the mission of community colleges. The CAOs describe the work they do to help fulfill the mission and how that work has changed during the COVID-19 pandemic. Advice is provided for those who aspire to the CAO position and for those responsible for developing future CAOs

Gender and Authority in the Public Sector: The Case of Local Government Chief Administrative Officers in the United States

In 2016, women represented 16.6% of all Chief Administrative Officers (CAOs) in local governments across the United States. Previous studies have investigated gender disparities in managerial representation, which is explained by the glass ceiling phenomenon; however, little is known about whether the women that occupy these male dominated positions have the similar levels of responsibilities as their male counterparts. Thus, the purpose of this dissertation is to understand if gender disparities in levels of work authority manifest as a new form of the glass ceiling. Work authority in this study is operationalized as CAOs’ sanctioning authority (control over personnel operations) and decision-making authority (control over formal operations). Using a mixed methods research design, this investigation is implemented in two phases. The first phase employs Ordinary Least Square (OLS) regression to explore the relationship between CAOs’ gender and CAOs’ level of work authority as well as the relationship between CAOs’ levels of work authority and annual pay. In the second phase, using a qualitative research method, I conduct an in-depth investigation of similarities and differences in the career paths of CAOs and the factors that shape their career-related decisions. This research has five main findings. First, female CAOs do not have similar level of sanctioning authority as their male counterparts. Second, disparities in level of sanctioning authority yield economic inequality among CAOs. Third, male and female CAOs take different career paths. Last, female CAOs perform dual roles—professional and personal—whereas most male CAOs are less burdened with household responsibilities in their personal lives. Last, for female CAOs with family responsibilities, their career paths are significantly fashioned by the presence of institutional and social support networks. Findings inform policy makers and public management practices. It informs that gender-based disparities in the workforce continually manifest in new forms, creating unequal employment opportunities for men and women in the workforce. Such disparities also continue perpetuating economic inequalities among men and women in the workforce. Also, it informs public management practices of the critical impact that institutional support has on leveling the playing field women to participate in male-dominated careers

Synoptic conditions and frontal dynamics during Cold Air Outbreaks in the Norwegian and Barents Sea

Cold Air Outbreaks (CAOs) in the Norwegian and Barents Sea are investigated using ERA Interim. The focus is on the synoptic conditions, heat fluxes, potential temperature tendencies and the frontogenesis at the onset of the CAOs. Four regions are investigated using the time series of the mean CAO index inside each region. Composite analysis is the core of this work. CAOs in each region are detected and separated with respect to the mean wind direction at 900 hPa at the time step where the CAOs are on their most intense stage. Composites for the different types of CAOs in the different regions are calculated. The separation shows that most CAOs are associated with northerlies when the mean CAO index is maximum. The composite analysis is supplemented by two case studies, one of a CAO in the Fram Strait, December 22-27, 2015 and another one in the Barents Sea, January 11-20, 2015. The results from the case and composite studies are compared, and they resemble each other. One of the main conclusions from this work is that there is typically a large scale cyclone advecting cold air off the ice edge. In addition, there is often some baroclinic growth at the onset of and during CAOs. It is confirmed that CAOs are associated with sensible and latent heat uxes, and hence diabatic heating, which is already well established from the literature. The different contributions to frontogenesis along the CAO front are investigated through both the case and the composite studies, using the frontogenesis function. It is found that CAOs in the Fram Strait associated with northerlies are associated with stronger circulation than CAOs in the Barents Sea associated with easterlies.Masteroppgave i meteorologi og oseanografiMAMN-GEOFGEOF39

CAOS spectroscopy of Am stars Kepler targets

The {\it Kepler} space mission and its {\it K2} extension provide photometric time series data with unprecedented accuracy. These data challenge our current understanding of the metallic-lined A stars (Am stars) for what concerns the onset of pulsations in their atmospheres. It turns out that the predictions of current diffusion models do not agree with observations. To understand this discrepancy, it is of crucial importance to obtain ground-based spectroscopic observations of Am stars in the {\it Kepler} and {\it K2} fields in order to determine the best estimates of the stellar parameters. In this paper, we present a detailed analysis of high-resolution spectroscopic data for seven stars previously classified as Am stars. We determine the effective temperatures, surface gravities, projected rotational velocities, microturbulent velocities and chemical abundances of these stars using spectral synthesis. These spectra were obtained with {\it CAOS}, a new instrument recently installed at the observing station of the Catania Astrophysical Observatory on Mt. Etna. Three stars have already been observed during quarters Q0-Q17, namely: HD\,180347, HD\,181206, and HD\,185658, while HD\,43509 was already observed during {\it K2} C0 campaign. We confirm that HD\,43509 and HD\,180347 are Am stars, while HD 52403, HD\,50766, HD\,58246, HD\,181206 and HD\,185658 are marginal Am stars. By means of non-LTE analysis, we derived oxygen abundances from O{\sc I}$\lambda$7771--5{\AA} triplet and we also discussed the results obtained with both non-LTE and LTE approaches.Comment: accepted in MNRAS main journal 13 pages, 11 figures, 3 tables. arXiv admin note: text overlap with arXiv:1404.095