17,402 research outputs found
The Effect of Disorder in an Orbitally Ordered Jahn-Teller Insulator
We study a two dimensional, two-band double-exchange model for
electrons coupled to Jahn-Teller distortions in the presence of quenched
disorder using a recently developed Monte-Carlo technique. In the absence of
disorder the half-filled system at low temperatures is an orbitally ordered
ferromagnetic insulator with a staggered pattern of Jahn-Teller distortions. We
examine the finite temperature transition to the orbitally disordered phase and
uncover a qualitative difference between the intermediate and strongly coupled
systems, including a thermally driven insulator to metal crossover in the
former case. Long range orbital order is suppressed in the presence of disorder
and the system displays a tendency towards metastable states consisting of
orbitally disordered stripe-like structures enclosing orbitally ordered
domains.Comment: 10 pages, 9 figure
Cost utility of fractional exhaled nitric oxide monitoring for the management of children asthma
Introduction
Fractional exhaled nitric oxide is a simple, non-invasive measurement of airway inflammation with minimal discomfort to the patient and with results available within a few minutes. This study aimed to evaluate the cost-effectiveness of asthma management using fractional exhaled nitric oxide monitoring in patients between 4 and 18 years of age.
Methods
A Markov model was used to estimate the cost-utility of asthma management using fractional exhaled nitric oxide monitoring versus asthma management without using fractional exhaled nitric oxide monitoring (standard therapy) in patients between 4 and 18 years of age. Cost data were obtained from a retrospective study on asthma from a tertiary center, in Medellin, Colombia, while probabilities of the Markov model and utilities were obtained from the systematic review of published randomized clinical trials. The analysis was carried out from a societal perspective.
Results
The model showed that fractional exhaled nitric oxide monitoring was associated with a lower total cost than standard therapy (US 1452 average cost per patient) and higher QALYs (0.93 vs. 0.92 average per patient). The probability that fractional exhaled nitric oxide monitoring provides a more cost-effective use of resources compared with standard therapy exceeds 99% for all willingness-to-pay thresholds.
Conclusion
Asthma management using fractional exhaled nitric oxide monitoring was cost-effective for treating patients between 4 and 18 years of age with mild to moderate allergic asthma. Our study suggests evidence that could be used by decision-makers to improve clinical practice guidelines, but this should be replicated in different clinical settings
Short-term adaptations following Complex Training in team-sports: A meta-analysis
Objective. The purpose of this meta-analysis was to study the short-term adaptations on sprint and vertical jump (VJ) performance following Complex Training (CT) in team-sports. CT is a resistance training method aimed at developing both strength and power, which has a direct effect on sprint and VJ. It consists on alternating heavy resistance training exercises with plyometric/power ones, set for set, on the same workout. Methods. A search of electronic databases up to July 2016 (PubMed-MEDLINE, SPORTDiscus, Web of Knowledge) was conducted. Inclusion criteria: 1) at least one CT intervention group; 2) training protocols ≥4-wks; 3) sample of team-sport players; 4) sprint or VJ as an outcome variable. Effect sizes (ES) of each intervention were calculated and subgroup analyses were performed. Results. A total of 9 studies (13 CT groups) met the inclusion criteria. Medium effect sizes (ES) (ES = 0.73) were obtained for pre-post improvements in sprint, and small (ES = 0.41) in VJ, following CT. Experimental-groups presented better post-intervention sprint (ES = 1.01) and VJ (ES = 0.63) performance than control-groups. Sprint. Large ESs were exhibited in younger athletes (12 total sessions (ES = 0.74). VJ. Large ESs in programs with >12 total sessions (ES = 0.81). Medium ESs obtained for under-Division I individuals (ES = 0.56); protocols with intracomplex rest intervals ≥2 min (ES = 0.55); conditioning activities with intensities ≤85% 1RM (ES = 0.64); basketball/volleyball players (ES = 0.55). Small ESs were found for younger athletes (ES = 0.42); interventions ≥6 weeks (ES = 0.45). Conclusions. CT interventions have positive medium effects on sprint performance and small effects on VJ in team-sport athletes. This training method is a suitable option to include in the season planning
Fuzzy synchronization of chaotic systems with hidden attractors
Chaotic systems are hard to synchronize, and no general solution exists. The presence of hidden attractors makes finding a solution particularly elusive. Successful synchronization critically depends on the control strategy, which must be carefully chosen considering system features such as the presence of hidden attractors. We studied the feasibility of fuzzy control for synchronizing chaotic systems with hidden attractors and employed a special numerical integration method that takes advantage of the oscillatory characteristic of chaotic systems. We hypothesized that fuzzy synchronization and the chosen numerical integration method can successfully deal with this case of synchronization. We tested two synchronization schemes: complete synchronization, which leverages linearization, and projective synchronization, capitalizing on parallel distributed compensation (PDC). We applied the proposal to a set of known chaotic systems of integer order with hidden attractors. Our results indicated that fuzzy control strategies combined with the special numerical integration method are effective tools to synchronize chaotic systems with hidden attractors. In addition, for projective synchronization, we propose a new strategy to optimize error convergence. Furthermore, we tested and compared different Takagi-Sugeno (T-S) fuzzy models obtained by tensor product (TP) model transformation. We found an effect of the fuzzy model of the chaotic system on the synchronization performance
Post-pandemic recovery strategies: revitalizing lifestyle entrepreneurship
The pandemic resulting from COVID-19 disease has brought about an unprecedented crisis to tourism destinations, resulting in an almost complete shutdown of tourist flows. Whereas disaster recovery models focus on prevention and preparedness, the post-pandemic recovery strategies are underexplored, particularly in relation to the highly representative group of small-scale businesses run by tourism lifestyle entrepreneurs (TLEs). An integrated framework for Destination Marketing Organization (DMO) strategic thinking is developed using the Delphi method with Q-sort technique. Findings from a 26-element expert panel emphasize the priority of creating a favorable environment for small-scale business development and supporting the provision of resources and capabilities. After this initial effort to strengthen these fragile businesses, it is essential to increase their communication capacity, a common limitation of TLEs, allowing these entrepreneurs to access niche markets more suited to the business and lifestyle they run. With stronger businesses, DMOs can enhance destination competitiveness and innovation, stimulating cooperation and networking.info:eu-repo/semantics/acceptedVersio
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