2,119 research outputs found
The Role of rescue therapies in the treatment of severe ARDS
ARDS is characterized by a non-cardiogenic pulmonary edema with bilateral chest radiograph opacities and hypoxemia refractory to oxygen therapy. It is a common cause of admission to the ICU due to hypoxemic respiratory failure requiring mechanical ventilation. Corticosteroids are not recommended in ARDS patients. Rescue therapies alleviate hypoxemia in patients unable to maintain reasonable oxygenation: recruitment maneuvers, prone positioning, inhaled nitric oxide, high-frequency oscillatory ventilation, and extracorporeal membrane oxygenation improve oxygenation, but their impact on mortality remains unproven. Restrictive fluid management seems to be a favorable strategy with no significant reduction in 60-d mortality. Future studies are needed to clarify the efficacy of these therapies on outcomes in patients with severe ARDS, and institution of these therapies may be considered on a case-by-case basis
The price of corporate social responsibility: the case of black economic empowerment transactions in South Africa
Since the demise of apartheid in South Africa, corporations have been encouraged to participate in the governmental goal of increasing corporate ownership by the black majority population. One vehicle that has arisen to help facilitate an increase in corporate ownership has been black economic empowerment (BEE) transactions. BEE transactions are essentially private placements of equity. Firms that have taken this socially activist position of selling portions of their equity, usually at a substantial discount, to black empowerment groups have received positive media attention in the name of âgood corporate citizenship.â ; This study investigates the market performance of these BEE transactions, specifically addressing three questions. The first question is whether BEE transactions create or destroy wealth. To address this question we use an event study methodology to calculate the cumulative abnormal returns (CARs) associated with public announcements of BEE transactions. The second question is whether specific types of BEE transactions did better or worse than others. We address this question by analyzing the cross-sectional variation in the CARs associated with public announcements of BEE transactions. The third question is whether firms that engage in BEE transactions experience negative post-announcement price performance. This last question is motivated by popular press accounts of the exploitation of black empowerment groups by white-owned South African corporations. To address this question, we test whether BEE transactions have benefited white corporate South Africa at the expense of the participating black empowerment groups.
Virtualit\ue0 al quadrato: proposta di sperimentazione di un ambiente didattico universitario in Second Life
Il presente lavoro intende esplorare le possibilit\ue0 offerte da
Second Life in ambito online-learning, sperimentando un
percorso di allestimento di ambienti di apprendimento in
ambito universitario attraverso metodologie didattiche e
strumenti che si avvalgono della sinergia fra due tecnologie:
da una parte, la ricostruzione tridimensionale di un contesto
formativo accademico utilizzando la piattaforma Second Life
valorizzata dall'introduzione di nuovi tool, dall'altra
l'interfacciamento con Moodle, nella delineazione di un
possibile utilizzo a livello didattico
The synergistic effect between positivity, socio-demographic factors and smoking cessation: results of a cohort study
OBJECTIVE: To examine the extent to which a effect does exist between Positivity (POS), smoking and socio-demographic factors in determining quitting smoking in subjects participating in a Group Counselling Program (GCP) for smoking cessation.METHODS: 481 subjects were contacted through a telephone call. A logistic regression analysis was carried out. Possible interaction between sociodemographic variables and POS level was tested using the Synergism Index (SI).RESULTS: For individuals with a POS level over or equal to 3.4 the odds of being smoker was significantly higher among females (OR = 1.55), who smoked at home (OR = 2.16) and lower if there had children at home (OR = 0.53). For individuals with a POS level under 3.4, the only significant variable associated with smoking was beinga female (OR = 2.58). As far concerns the synergistic effect between the variables considered does exist between POS levels and having children at home (SI=1.13) and female gender (SI = 2.8).CONCLUSIONS: The synergistic effect between POS and sociodemographic factors adds evidence on the use of POS as possible determinants of individual happiness
Luenberger observers for switching discrete-time linear systems
State estimation is considered for a class of switching discrete-time linear systems. The switching is assumed to be unknown among the various system modes associated with different known matrices. The proposed scheme relies on the combination of the estimation of the system mode with the application of a Luenberger-like observer whose gain is a function of the estimated mode. In the absence of noises, the estimate of the mode can be chosen among the ones that are consistent with the measurements and the stability of the estimation error is ensured under suitable conditions on the observer gains. Such conditions can be expressed by means of linear matrix inequalities (LMIs). The presence of bounded disturbances is also taken explicitly into consideration. In this situation, a novel method based on a minimum-distance criterion is proposed in order to estimate the system mode. Also in this case the error of the resulting estimator is proved to be exponentially bounded
Enumerating Abelian Returns to Prefixes of Sturmian Words
We follow the works of Puzynina and Zamboni, and Rigo et al. on abelian
returns in Sturmian words. We determine the cardinality of the set
of abelian returns of all prefixes of a Sturmian word in
terms of the coefficients of the continued fraction of the slope, dependingly
on the intercept. We provide a simple algorithm for finding the set
and we determine it for the characteristic Sturmian words.Comment: 19page
Optimal propagating fronts using Hamilton-Jacobi equations
The optimal handling of level sets associated to the solution of Hamilton-Jacobi equations such as the normal flow equation is investigated. The goal is to find the normal velocity minimizing a suitable cost functional that accounts for a desired behavior of level sets over time. Sufficient conditions of optimality are derived that require the solution of a system of nonlinear Hamilton-Jacobi equations. Since finding analytic solutions is difficult in general, the use of numerical methods to obtain approximate solutions is addressed by dealing with some case studies in two and three dimensions
Reverse Engineering of a Racing Motorbike Connecting Rod
The following scientific paper aims to analyze in detail the methodology for reverse engineering of a racing motorcycle connecting rod. The objective is to start with a product available on the market as a spare part, reconstruct its CAD model with a high standard of accuracy, then proceed with lightening modifications to arrive at a new, improved design. The innovative aspect of the procedure lies in the fact that in order to ensure accuracy on the order of a tenth of a millimeter during reconstruction, it was decided to use a FARO articulated arm laser to scan the componentâs outer surface. By taking advantage of appropriate redesign CAD software (Geomagic Design X), a reconstruction can proceed within the high standard of accuracy imposed. In conclusion, the modifications made through material removal allow an improvement in product efficiency, ensuring high performance
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