[1] In variational data assimilation systems, background error covariances are often estimated from a temporal and spatial average. For a limited area model such as the Aire Limited Adaptation Dynamique Developpment International (ALADIN)/France, the spatial average is calculated over the regional computation domain, which covers western Europe. The purpose of this study is to revise the temporal stationarity assumption by diagnosing time variations of such regionally averaged covariances. This is done through examination of covariance changes as a function of season (winter versus summer), day (in connection with the synoptic situation), and hour (related to the diurnal cycle), with the ALADIN/France regional ensemble Three-Dimensional Variational analysis (3D-Var) system. In summer, compared to winter, average error variances are larger, and spatial correlation functions are sharper horizontally but broader vertically. Daily changes in covariances are particularly strong during the winter period, with larger variances and smaller-scale error structures when an unstable low-pressure system is present in the regional domain. Diurnal variations are also significant in the boundary layer in particular, and, as expected, they tend to be more pronounced in summer. Moreover, the comparison between estimates provided by two independent ensembles indicates that these covariance time variations are estimated in a robust way from a six-member ensemble. All these results support the idea of representing these time variations by using a real-time ensemble assimilation system. Citation: Monteiro, M., and L. Berre (2010), A diagnostic study of time variations of regionally averaged background error covariances,
[1] The operational ALADIN-France 3D-Var system is based on static background error covariances calculated off-line during a few week past period. In this study, the impact of an online updated specification of background error covariances is evaluated in the ALADIN-France system. This evaluation is done by comparing three experiments, respectively based on (i) covariances calculated from a monthly average over a past period, (ii) covariances calculated from a monthly average over the period of study, and (iii) covariances calculated from a sliding daily average over the period of study. First, it is shown through a comparison between experiments (i) and (ii) that updating the monthly average of error covariances has a positive impact on the short-range forecast quality. This is related to the specification of covariances which are more representative of average weather regimes at play during the period of study. Second, a comparison between experiments (ii) and (iii) indicates that additional positive impacts of a daily update of error covariances are also visible, although they tend to be somewhat localized and modest during this period. These impacts are illustrated by case studies for humidity during an anticyclonic situation, and for wind during a cyclonic event. These results support the idea to consider an online updated specification of background error covariances.
OBJECTIVE Timing of mobilization after chronic subdural hematoma (cSDH) surgery is highly heterogeneous among neurosurgical centers. Past studies have suggested that early mobilization may reduce medical complications without increasing recurrence, but evidence remains scarce. The purpose of this study was to compare an early mobilization protocol with a 48-hour bed rest practice, with a focus on the occurrence of medical complications. METHODS The GET-UP Trial is a prospective, randomized, unicentric, open-label study with an intention-to-treat primary analysis designed to evaluate the impact of an early mobilization protocol after burr hole craniostomy for cSDH on the occurrence of medical complications and functional outcomes. A total of 208 patients were recruited and randomly assigned to either an early mobilization group where they began head-of-bed elevation within the first 12 hours after surgery and proceeded to sedestation, orthostatism, and/or walking as rapidly as tolerated, or to a bed rest group where they remained recumbent with a head-of-bed angle inferior to 30° for 48 hours after surgery. The primary outcome was the occurrence of a medical complication (defined as either an infection, seizure, or thrombotic event) after surgery and until clinical discharge. Secondary outcomes included length of stay measured from randomization to clinical discharge, surgical hematoma recurrence at clinical discharge and 1 month after surgery, and Glasgow Outcome Scale–Extended (GOSE) assessment at clinical discharge and 1 month after surgery. RESULTS A total of 104 patients were randomly assigned to each group. No significant baseline clinical differences were observed before randomization. The primary outcome occurred in 36 (34.6%) patients included in the bed rest group and 20 (19.2%) in the early mobilization group (p = 0.012). At 1 month after surgery, a favorable functional outcome (defined as GOSE score ≥ 5) was observed in 75 (72.1%) patients in the bed rest group and 85 (81.7%) in the early mobilization group (p = 0.100). Surgical recurrence occurred in 5 (4.8%) patients in the bed rest group and 8 (7.7%) in the early mobilization group (p = 0.390). CONCLUSIONS The GET-UP Trial is the first randomized clinical trial to assess the impact of mobilization strategies on medical complications after burr hole craniostomy for cSDH. Early mobilization was associated with a reduction in medical complications without a significant effect on surgical recurrence, compared with a 48-hour bed rest protocol.
In an increasingly competitive environment subject to uncontrollable risks, the continuity of organizations can be severely threatened, and the decision-making process takes place under circumstances of great uncertainty. Therefore, it is necessary to develop strategies and competencies that allow the business to thrive. Startups, particularly technology-based ones, are an essential source of innovation. However, several studies indicate that approximately 60% of Startups fail in the first five years of business. To succeed, startups need to develop skills that allow them to rapidly evaluate their decisions and options, and to identify what is vital for the survival of their business. Thus, organizational resilience becomes of paramount importance to those companies. The term resilience is used in different areas of knowledge, but all the definitions share common ground regarding the concept: it describes the ability of an element to return to its normal state after a period of stress and crisis. The main objective of this exploratory research developed in Portugal is to identify the resilience factors of technological Startups. It is also intended to contribute to the design and development of instruments which promote organizational resilience in technological ecosystems. The current research follows the case study methodology based on a sample of 10 technological startups collected from the Startup Leiria ecosystem (Portugal). The Startup Leiria is an incubator of startup ventures which makes it a prime source of data and knowledge. The main findings point out the necessity to develop agility skills in Startup ecosystems. It was concluded that resilient organizations are characterized by having the ability to anticipate, respond, adapt, and recover from a disruptive event. The uniqueness of this study concerns its contribution to stimulate data-driven discussions regarding the necessity to implement programs for the reskilling of Startups in the context of their ecosystems.
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