77 research outputs found
Collective modes of a quasi two-dimensional Bose condensate in large gas parameter regime
We have theoretically studied the collective modes of a quasi two-dimensional
(Q2D) Bose condensate in the large gas parameter regime by using a formalism
which treats the interaction energy beyond the mean-field approximation. In the
calculation we use the perturbative expansion for the interaction energy by
incorporating the Lee, Huang and Yang (LHY) correction term. The results show
that incorporation of this higher order term leads to detectable modifications
in the mode frequencies.Comment: 10 pages, 2 figure
Role of inertia in the starting and stopping mechanisms of granular flows
It is well-known that a pile of grains starts and stops flowing at different angles of repose. It is also known that such starting and stopping angles exhibit thickness-dependent behaviour, with deeper layers beginning to flow more readily and arresting at lower angles than shallower materials. These considerations have motivated various rheological assumptions in granular constitutive laws. This paper demonstrates that such observations can instead be partly attributed to inertial effects. In particular, we examine the roles of two control parameters characterising conventional chute flow experiments: the rate of inclination of the chute, and the threshold surface velocity associated with identification of the flow. Both of these parameters control the system’s momentum at different instances. We perform two-dimensional discrete-element simulations and also develop a one-dimensional analytic model based on the standard μ(I)-rheology. Results indeed indicate a difference between the starting and stopping angles as well as a thickness-dependency, despite the absence of any hysteresis or material length scale in the underlying rheological model. Higher threshold velocities are shown to produce higher angles at which flow begins. In addition, the starting/stopping angle increases/decreases with the applied inclination rate. For thick enough granular layers, no matter how small the rate is, critical angles are shown to deviate from the quasi-static limit. Therefore, inertial effects should not a priori be neglected. To finalise our argument, we show the effect of the inclination rate and the threshold velocity in a laboratory set-up, using small-scale experiments of an inclined chute
Time for a paradigm shift in shared decision-making in trauma and emergency surgery? Results from an international survey
Background: Shared decision-making (SDM) between clinicians and patients is one of the pillars of the modern patient-centric philosophy of care. This study aims to explore SDM in the discipline of trauma and emergency surgery, investigating its interpretation as well as the barriers and facilitators for its implementation among surgeons. Methods: Grounding on the literature on the topics of the understanding, barriers, and facilitators of SDM in trauma and emergency surgery, a survey was created by a multidisciplinary committee and endorsed by the World Society of Emergency Surgery (WSES). The survey was sent to all 917 WSES members, advertised through the society’s website, and shared on the society’s Twitter profile. Results: A total of 650 trauma and emergency surgeons from 71 countries in five continents participated in the initiative. Less than half of the surgeons understood SDM, and 30% still saw the value in exclusively engaging multidisciplinary provider teams without involving the patient. Several barriers to effectively partnering with the patient in the decision-making process were identified, such as the lack of time and the need to concentrate on making medical teams work smoothly. Discussion: Our investigation underlines how only a minority of trauma and emergency surgeons understand SDM, and perhaps, the value of SDM is not fully accepted in trauma and emergency situations. The inclusion of SDM practices in clinical guidelines may represent the most feasible and advocated solutions
A laboratory-numerical approach for modelling scale effects in dry granular slides
Granular slides are omnipresent in both natural and industrial contexts. Scale effects are changes in physical behaviour of a phenomenon at different geometric scales, such as between a laboratory experiment and a corresponding larger event observed in nature. These scale effects can be significant and can render models of small size inaccurate by underpredicting key characteristics such as ow velocity or runout distance. Although scale effects are highly relevant to granular slides due to the multiplicity of length and time scales in the flow, they are currently not well understood. A laboratory setup under Froude similarity has been developed, allowing dry granular slides to be investigated at a variety of scales, with a channel width configurable between 0.25-1.00 m. Maximum estimated grain Reynolds numbers, which quantify whether the drag force between a particle and the surrounding air act in a turbulent or viscous manner, are found in the range 102-103. A discrete element method (DEM) simulation has also been developed, validated against an axisymmetric column collapse and a granular slide experiment of Hutter and Koch (1995), before being used to model the present laboratory experiments and to examine a granular slide of significantly larger scale. This article discusses the details of this laboratory-numerical approach, with the main aim of examining scale effects related to the grain Reynolds number. Increasing dust formation with increasing scale may also exert influence on laboratory experiments. Overall, significant scale effects have been identified for characteristics such as ow velocity and runout distance in the physical experiments. While the numerical modelling shows good general agreement at the medium scale, it does not capture differences in behaviour seen at the smaller scale, highlighting the importance of physical models in capturing these scale effects
Biomarker-guided antibiotic duration for hospitalized patients with suspected sepsis: the ADAPT-sepsis randomized clinical trial
Importance: For hospitalized critically ill adults with suspected sepsis, procalcitonin (PCT) and C-reactive protein (CRP) monitoring protocols can guide the duration of antibiotic therapy, but the evidence of the effect and safety of these protocols remains uncertain.
Objective: To determine whether decisions based on assessment of CRP or PCT safely results in a reduction in the duration of antibiotic therapy.
Design, Setting, and Participants: A multicenter, intervention-concealed randomized clinical trial, involving 2760 adults (≥18 years), in 41 UK National Health Service (NHS) intensive care units, requiring critical care within 24 hours of initiating intravenous antibiotics for suspected sepsis and likely to continue antibiotics for at least 72 hours.
Intervention: From January 1, 2018, to June 5, 2024, 918 patients were assigned to the daily PCT-guided protocol, 924 to the daily CRP-guided protocol, and 918 assigned to standard care.
Main Outcomes and Measures: The primary outcomes were total duration of antibiotics (effectiveness) and all-cause mortality (safety) to 28 days. Secondary outcomes included critical care unit data and hospital stay data. Ninety-day all-cause mortality was also collected.
Results: Among the randomized patients (mean age 60.2 [SD, 15.4] years; 60.3% males), there was a significant reduction in antibiotic duration from randomization to 28 days for those in the daily PCT-guided protocol compared with standard care (mean duration, 10.7 [SD, 7.6] days for standard care and 9.8 [SD, 7.2] days for PCT; mean difference, 0.88 days; 95% CI, 0.19 to 1.58, P = .01). For all-cause mortality up to 28 days, the daily PCT-guided protocol was noninferior to standard care, where the noninferiority margin was set at 5.4% (19.4% [170 of 878] of patients receiving standard care; 20.9% [184 of 879], PCT; absolute difference, 1.57; 95% CI, −2.18 to 5.32; P = .02). No difference was found in antibiotic duration for standard care vs daily CRP-guided protocol (mean duration, 10.6 [7.7] days for CRP; mean difference, 0.09; 95% CI, −0.60 to 0.79; P = .79). For all-cause mortality, the daily CRP-guided protocol was inconclusive compared with standard care (21.1% [184 of 874] for CRP; absolute difference, 1.69; 95% CI, −2.07 to 5.45; P = .03).
Conclusions and Relevance: Care guided by measurement of PCT reduces antibiotic duration safely compared with standard care, but CRP does not. All-cause mortality for CRP was inconclusive.
Trial Registration: isrctn.org Identifier: ISRCTN4747324
Population effectiveness of the pentavalent and monovalent rotavirus vaccines: a systematic review and meta-analysis of observational studies
Differences in Periodontal Parameters, Serum Vitamin D, Calcium, Phosphorus, Alkaline Phosphatase and C-Reactive Protein Between Perimenopausal and Postmenopausal Women with Periodontitis
Objective: The study aimed to evaluate and compare the differences in periodontal and biochemical parameters between perimenopausal and postmenopausal women with periodontitis. Methods: A cross-sectional study was conducted on 100 women with chronic periodontitis, aged 40-60 years, divided into 50 perimenopausal and 50 postmenopausal groups. Periodontal parameters (plaque index PI, gingival index GI, gingival bleeding index GBI, simplified debris index DI-S, simplified calculus index CI-S, simplified oral hygiene index OHI-S, clinical attachment loss CAL, and pocket depth PD) and blood samples were collected to estimate vitamin D, calcium Ca, phosphorous P, alkaline phosphatase ALP and C-reactive protein CRP. Results: The mean values of clinical periodontal parameters were significantly higher in the postmenopausal group as compared to the perimenopausal group (P 0.05), except for CI-S (P 0.05). For the biochemical parameters, the mean serum level of AlP, Ca, and P were within the normal reference ranges, with non-significant differences reported between both groups regarding ALP and P (P 0.05). While serum Vit.D level was more significantly reduced in the postmenopausal group (P 0.05), and CRP levels were increased in both groups, but with non-significant differences (P 0.05). Conclusions: Postmenopause could more significantly affect the progression severity of periodontal disease and vitamin D deficiency than peri menopause due to reducing circulating estrogen level
Shigella infection in children under 5 years old in western French Guiana
AbstractFrench Guiana, a tropical country, is characterised by a young and multi-ethnic population. Difficulties in accessing safe water sources lead to outbreaks of gastroenteritis. The objectives of this study were (1) to describe the microbiological profile of shigella strains isolated in western French Guiana, including antimicrobial susceptibility and the distribution of strains in terms of species and serotypes and (2) to estimate the incidence of shigellosis in children under 5 years old. A retrospective observational study was conducted of 213 cases of shigellosis diagnosed in the biology department of the hospital centre for western French Guiana between 2000 and 2012 in children under 5 years old. The serogroups (formerly known as species) that predominates in French Guiana wasShigella flexneri. No resistance was observed to fluoroquinolones or to third-generation cephalosporins. The average incidence of shigellosis in children under 5 years old in western French Guiana was estimated at 189.6 cases per 100 000 inhabitants per year. Shigellosis is a public health problem in western French Guiana. These infections suggest the difficulties in accessing safe water sources and the lack of public sanitation. A quadrivalent vaccine containingShigella sonneiand three serotypes ofS. flexneri(S. flexneri2a, 3a and 6) could provide broad coverage against shigella infections.</jats:p
Recognition of the granular airborne portion in a flighted rotary drum
International audienceThis article deals with numerical simulation via Discrete Element Method (DEM) in a flighted rotary drum with a varying number of flights from 1 to 25 at a constant load of particles. The granular behavior kinematics is studied in the three regimes: under-, design- and over-loading. It was shown that the behavior of granular material during the unloading process from the flights governs the regime transitions. The cross-sectional distribution analysis of the granular material in the different parts of the drum established the existence of two dense media (bed and flights) and one dilute medium (in the airborne portion). Since one of the criteria that affect the efficiency of heat transport between the gas and the particle media is the number of particles in the airborne phase, three recognition methods are proposed to detect the airborne portion. Based on geometry, velocity magnitude, and minimal separation distance, the comparison between them provides a basis for discussion about the relevance of each method in detecting these airborne particles
- …
