On the validity of Damköhler's first hypothesis in turbulent Bunsen burner flames: A computational analysis

The validity of Damköhler's first hypothesis, which relates the turbulent flame speed to turbulent flame surface area under the condition where the integral length scale of turbulence is greater than the flame thickness, has been assessed using three-dimensional Direct Numerical Simulations (DNS) of turbulent premixed Bunsen burner flames over a range of values of Reynolds number, pressure and turbulence intensity. It has been found for the Bunsen configuration that the proportionality between volume-integrated burning rate and the overall flame surface area is not strictly maintained according to Damköhler's first hypothesis. The discrepancy is found to originate physically from the local stretch rate dependence of displacement speed, and this helps to explain differences observed previously between flames with and without mean curvature. Approximating the local density-weighted flame propagation speed with the unstrained laminar burning velocity is shown to be inaccurate, and can have a significant influence on the prediction of the overall burning rate for flames with non-zero mean curvature. Using a two-dimensional projection of the actual scalar gradient for flame area evaluation is shown to exacerbate the loss of proportionality between volume-integrated burning rate and the overall flame surface area. The current analysis identifies the conditions under which Damköhler's hypothesis remains valid and the necessary correction for non-zero mean flame curvature. Further, it has been demonstrated that surface-weighted stretch effects on displacement speed need to be accounted for in order to ensure the validity of Damköhler's hypothesis under all circumstances. Finally, it has been found that the volume-integrated density-weighted scalar dissipation rate remains proportional to the overall burning rate for all flames considered here irrespective of the value of Reynolds number, pressure and turbulence intensity. However, this proportionality is lost when the scalar dissipation rate is evaluated using the two-dimensional projection of the actual scalar gradient

Analysis of genes and their transcripts in myotonic dystrophy

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN031165 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Dermatology residents as educators: a qualitative study of identity formation

Abstract Background One of the many identities a physician comes to form during their career is their identity as an educator. Exploring formation of this identity may enrich our understanding of how physicians make decisions related to their roles as educators, their behaviors, and how this ultimately influences the educational environment. It is the aim of this study to investigate educator identity formation of dermatology residents while early in their careers. Methods Drawing on a social constructionist paradigm, we conducted a qualitative study, utilizing an interpretative approach. We examined longitudinal data over a 12-month period using dermatology residents’ written reflections from their professional portfolios and semi-structured interviews. We collected this data as we progressed through and beyond a 4-month professional development program designed to encourage residents’ growth as educators. Sixty residents in their second, third, or final year of residency programs located in Riyadh, Saudi Arabia were invited to take part in this study. Twenty residents participated with sixty written reflections and 20 semi-structured interviews. Qualitative data were analyzed using a thematic analysis approach. Results Sixty written reflections and 20 semi-structured interviews were analyzed. Data was categorized according to themes corresponding to the original research questions. For the first research question regarding identity formation, themes included definitions of education, the process of education, and identity development. For the second research question, 1 theme entitled professional development program included, the following sub-themes: individual act, interpersonal activity, and an organizational undertaking, with many believing that residency programs should prepare residents for their educator roles. Participants also described newfound leadership ambitions of creating new dermatology fellowship programs as a result of taking part in the Resident-as-Educator program. Conclusions Our study provides insights on the dynamic formation of educator identities amongst dermatology residents. Investment in developing residents as educators through professional development programs may instigate transformational change on the individual physician level and profession’s level

A Low-cost, Sterile System for Fat Collection Using a Syringe Tube as a Reservoir

Summary:. Fat grafting is a widely performed procedure in the field of plastic surgery. It involves fat extraction, processing, and injection into a recipient site. It is imperative that the fat is collected and processed in a sterile system. A wide variety of equipment is required to perform the procedure (eg, a liposuction device, a vacuum pump, and syringes). Limitations often arise in the operating room, especially in low-resource areas, where task-specific equipment might be unavailable. This can present an opportunity for the surgeon to improvise and create a temporary solution. In this report, we describe our solution in dealing with the unavailability of a sterile vacuum pump canister during a large volume fat grafting procedure. We constructed a sterile reservoir using two syringes, through which negative pressure was delivered without breaking sterility. The items used were a 60-cm3 syringe barrel, a 10-cm3 syringe barrel, a 60-cm3 syringe plunger seal, a tube connected to the nonsterile vacuum pump, and the liposuction cannula. This technique allowed us to extract the fat in a sterile environment under the assistance of a suction device. Our novel technique was used for harvesting fat in a sterile reservoir, while still utilizing the assisted suction from the nonsterile vacuum pump, without breaking sterility