What are communities of practice? A comparative review of four seminal works

This paper is a comparative review of four seminal works on communities of practice. It is argued that the ambiguities of the terms community and practice are a source of the concept's reusability allowing it to be reappropriated for different purposes, academic and practical. However, it is potentially confusing that the works differ so markedly in their conceptualizations of community, learning, power and change, diversity and informality. The three earlier works are underpinned by a common epistemological view, but Lave and Wenger's 1991 short monograph is often read as primarily about the socialization of newcomers into knowledge by a form of apprenticeship, while the focus in Brown and Duguid's article of the same year is, in contrast, on improvising new knowledge in an interstitial group that forms in resistance to management. Wenger's 1998 book treats communities of practice as the informal relations and understandings that develop in mutual engagement on an appropriated joint enterprise, but his focus is the impact on individual identity. The applicability of the concept to the heavily individualized and tightly managed work of the twenty-first century is questionable. The most recent work by Wenger – this time with McDermott and Snyder as coauthors – marks a distinct shift towards a managerialist stance. The proposition that managers should foster informal horizontal groups across organizational boundaries is in fact a fundamental redefinition of the concept. However it does identify a plausible, if limited, knowledge management (KM) tool. This paper discusses different interpretations of the idea of 'co-ordinating' communities of practice as a management ideology of empowerment

Guillain-Barré syndrome during the Zika virus outbreak in Northeast Brazil: An observational cohort study

Objective: To determine the clinical phenotype of Guillain-Barré syndrome (GBS) after Zika virus (ZIKV) infection, the anti-glycolipid antibody signature, and the role of other circulating arthropod-borne viruses, we describe a cohort of GBS patients identified during ZIKV and chikungunya virus (CHIKV) outbreaks in Northeast Brazil. Methods: We prospectively recruited GBS patients from a regional neurology center in Northeast Brazil between December 2014 and February 2017. Serum and CSF were tested for ZIKV, CHIKV, and dengue virus (DENV), by RT-PCR and antibodies, and serum was tested for GBS-associated antibodies to glycolipids. Results: Seventy-one patients were identified. Forty-eight (68%) had laboratory evidence of a recent arbovirus infection; 25 (52%) ZIKV, 8 (17%) CHIKV, 1 (2%) DENV, and 14 (29%) ZIKV and CHIKV. Most patients with a recent arbovirus infection had motor and sensory symptoms (72%), a demyelinating electrophysiological subtype (67%) and a facial palsy (58%). Patients with a recent infection with ZIKV and CHIKV had a longer hospital admission and more frequent mechanical ventilation compared to the other patients. No specific anti-glycolipid antibody signature was identified in association with arbovirus infection, although significant antibody titres to GM1, GalC, LM1, and GalNAc-GD1a were found infrequently. Conclusion: A large proportion of cases had laboratory evidence of a recent infection with ZIKV or CHIKV, and recent infection with both viruses was found in almost one third of patients. Most patients with a recent arbovirus infection had a sensorimotor, demyelinating GBS. We did not find a specific anti-glycolipid antibody signature in association with arbovirus-related GBS

Confirmatory platelet-activating factor receptor antagonist trial in patients with severe gram-negative bacterial sepsis: a phase III, randomized, double-blind, placebo-controlled, multicenter trial. BN 52021 Sepsis Investigator Group.

OBJECTIVE: To determine the efficacy and safety of using natural platelet-activating factor receptor antagonist (PAFra), BN 52021, to treat patients with severe Gram-negative bacterial sepsis. DESIGN: A prospective, randomized, double-blind, placebo-controlled, multicenter clinical trial. SETTING: Fifty-nine academic medical center intensive care units in Europe. PATIENTS: Six hundred nine patients with severe sepsis, suspected to be related to Gram-negative bacterial infection, who received PAFra or placebo. INTERVENTIONS: Patients were randomized to receive either a dose of PAFra (120 mg iv) every 12 hrs over a 4-day period or placebo over a 4-day period. MEASUREMENTS AND MAIN RESULTS: The patients were well matched at study entry for severity of illness and for risk factors known to influence the outcome of sepsis. Among all randomized patients, the 28-day, all-cause mortality rate was 49% (152/308) in the placebo group, and 47% (140/300) in the PAFra group (p=.50). When analyzed on the basis of the previously defined target population, the 28-day, all-cause mortality rate was 50% (115/232) in the placebo group and 44% (94/212) in the PAFra group, yielding a 12% reduction in mortality rate (p=.29). In patients with documented infection involving other organisms, there was no difference between treated and placebo groups. When the outcomes of organ dysfunctions were examined in the overall population and in the documented Gram-negative bacterial infection population, the number of patients who resolved hepatic dysfunction tended to be higher in the treated group than in the placebo group (p=.06). The number of adverse events reported were not different between the two groups. CONCLUSIONS: A 4-day administration of the studied PAFra (BN 52021) failed to demonstrate a statistically significant reduction in the mortality rate of patients with severe sepsis suspected to be related to Gram-negative bacterial infection. If PAFra treatment has any therapeutic activity in severe Gram-negative bacterial sepsis, the incremental benefits are small and will be difficult to demonstrate in a patient population as defined by this clinical trial

Solidification of Sn-0.7Cu-0.15Zn solder: In situ observation

High resolution time-resolved X-ray imaging with synchrotron radiation was used for in situ observation of four distinct events during solidification of a Sn-0.7Cu-0.15Zn solder despite small composition and density differences. These included bSn dendrite growth, Sn-CuSn univariant eutectic growth, microporosity formation, and a polyphase reaction in the last stages of freezing. The development of microstructure was described quantitatively by tracking the loci of dendrite tips during grain growth. The results have implications for microstructure control and the understanding of structure-property relationships in Sn-Cu-Zn lead-free solders