Mathematical modelling of curtain coating

We present a simple mathematical model for the fluid flow in the curtain coating process, exploiting the small aspect ratio, and examine the model in the large-Reynolds-number limit of industrial interest. We show that the fluid is in free fall except for a region close to the substrate, but find that the model can not describe the turning of the curtain onto the substrate. We find that the inclusion of a viscous bending moment close to the substrate allows the curtain to “turn the corner”

Update on treatment of follicular non-Hodgkin’s lymphoma: focus on potential of bortezomib

Follicular lymphoma is predominantly managed as a chronic disease, with intermittent chemo/immunotherapy reserved for symptomatic progression. It is considered incurable with conventional treatments, and current therapeutic options are associated with significant toxicities that are especially limiting in older patients. Bortezomib (PS-341; Velcade®), a first-in-class drug targeting the proteolytic core subunit of the 26S proteasome, has emerged as a therapeutic alternative in follicular lymphoma, with promising preclinical data and efficacy in patients with other hematological malignancies. Several clinical trials were conducted with bortezomib for the treatment of non-Hodgkin’s lymphoma. As a single agent, overall responses in follicular lymphoma varied greatly (16%–41%), with weekly bortezomib showing less neurotoxicity than twice-weekly regimens, but with concern about decreased responses. Combination with rituximab was projected to improve the efficacy of bortezomib, but this resulted in increased toxicities and questionable added benefit. Although the largest Phase III study in follicular lymphoma of bortezomib plus rituximab versus rituximab alone demonstrated a significant progression-free survival difference, the absolute difference was small (12.8 months versus 11 months). Combining bortezomib with established regimens, such as rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP), rituximab, cyclophosphamide, vincristine, and prednisone (R-CVP), or rituximab-bendamustine also did not show definite benefit, and many of these studies did not meet their primary endpoint when bortezomib failed to improve responses or survival to the degree anticipated. In a disease where the goal of treatment is palliative and affected patients often have other medical and treatment-related comorbidities, decisions regarding therapies which carry risks of additional toxicities must be considered carefully. Conclusive evidence of the ability of bortezomib to improve patient outcomes meaningfully and to justify the added toxicity is lacking, but limitations in cross-trial comparisons are recognized. Large randomized trials and investigations of combinations with promising novel targeted agents will aid in determining the role of bortezomib, if any, in the future treatment of follicular lymphoma

Responses of Swimmers Caught in Rip Currents: Perspectives on Mitigating the Global Rip Current Hazard

Rip currents are the primary mechanism on many of the world’s beaches associated with rescues and drownings and have long been the focus of beachgoer education and awareness strategies. Traditional approaches to mitigating the rip current hazard typically provide information on escape procedures for beachgoers caught in a rip current. Several of these approaches are now being challenged by new scientific findings leading to uncertainty and debate amongst scientists and beach safety practitioners. This paper suggests that future research efforts on mitigating the rip current hazard should focus on quantifying the physical and behavioral responses of beachgoers who have been caught in rip currents. Descriptions of new approaches adopted recently in Australia by a joint collaboration between the University of New South Wales and Surf Life Saving Australia are presented

YouTube Videos and the Rip Current Hazard: Swimming in a Sea of (Mis)information

Rip currents are strong, narrow, offshore flows found on many global beaches and contribute to hundreds of drownings and tens of thousands of rescues each year. Yet despite long-standing educational efforts, public understanding of rip currents is poor. YouTube represents a new visual-based social media platform with the potential to educate a large and global audience about the rip current hazard. This study analyzed the content of 256 rip current–related YouTube videos with over 5 million total views as of March 2, 2015 finding that the accuracy of information disseminated about rip currents on YouTube is mixed and of varying quality. Existing videos are good at emphasizing correct rip current terminology, visual imagery, and a range of escape strategies, but greater emphasis in future videos must be placed on rip current avoidance, particularly through promoting the need to swim near lifeguards and how to spot rip currents

Who rescues who? Understanding aquatic rescues in Australia using coronial data and a survey

Objective: To examine fatal drowning associated with aquatic rescues and prior self‐reported experience of undertaking an aquatic rescue in Australia. Methods: Previous aquatic rescue experience was sourced through the 2013 Queensland Computer Assisted Telephone Instrument Survey and compared to data on rescue‐related fatal unintentional drowning between 1 January 2006 and 31 December 2015. Results: Twenty‐three per cent (n=294/1291) of survey respondents had previously performed an aquatic rescue. Males (X2=35.2; p<0.001) were more likely to have performed a rescue; commonly at a beach/ocean/harbour location (X2=13.5; p<0.001). Females were more likely to have rescued a child (0‐4 years of age) (X2=29.2; p<0.001) from a swimming pool (X2=34.3; p<0.001). Fifty‐one people drowned while performing an aquatic rescue (Males=82.4%; 25–44 years of age=53.0%; beaches=54.9%). Conclusions: Drownings are prevented by bystanders; this is not without risk to the rescuer. Most people perform only one rescue in their life, often at a younger age, on an altruistic basis, of family members or young children. Community‐wide rescue skills, taught at a young age, with consideration for coastal, inland and swimming pool environments, may prevent drowning

Dying to help: fatal bystander rescues in Australian coastal environments

Bystanders who drown during a rescue attempt in aquatic waterways are becoming an increasingly important issue within drowning prevention. In the Australian context, the majority of these incidents occur in coastal water ways. This study documents and characterizes bystander rescuer fatalities within Australian coastal waterways that occurred between 1 July 2004 and 30 June 2019 in order to provide suggestions for future public safety interventions involving bystander rescuers. Data was sourced through Surf Life Saving Australia's (SLSA) Coastal Fatality Database, which collates information from multiple sources. Sixty-seven bystander rescuer fatalities in coastal waterways were reported during the 15-year period, an average of 4.5 per year, which is a significant proportion of the five fatalities previously reported across all Australian waterways. The majority of coastal bystander rescuer fatality incidents occurred in the state of New South Wales (49%), at beaches (64%), in regional or remote areas (71%), more than 1 km from the nearest lifesaving service (78%), during summer (45%), in the afternoon (72%), in the presence of rip currents (73%), and did not involve the use of flotation devices to assist rescue (97%). The majority of coastal bystander rescuer victims were Australian residents (88%) born in Australia/Oceania (68%), males (81%), aged between 30-44 years old (36%), visitors to the location (55%), either family (69%) or friends (15%) of the rescuee(s), and were attempting to rescue someone younger than 18 years old (64%). Our results suggest future safety intervention approaches should target males, parents and carers visiting beach locations in regional locations during holiday times and should focus on the importance of flotation devices when enacting a rescue and further educating visitors about the rip current hazard. Future research should examine the psychology of bystander rescue situations and evaluate the effectiveness of different safety intervention approaches

Characteristics of aquatic rescues undertaken by bystanders in Australia

An issue of growing importance within the field of drowning prevention is the undertaking of aquatic rescues by bystanders, who sometimes drown in the process. The main objectives of this study were to describe characteristics of bystanders making rescues in different Australian aquatic environments, identify the role of prior water safety training in conducting bystander rescues and provide insights into future public education strategies relating to bystander rescue scenarios. An online survey was disseminated via various social media platforms in 2017 and gathered a total of 243 complete responses. The majority of bystander rescues described took place in coastal waterways (76.5%; n = 186), particularly beaches (n = 67), followed by pools (17.3%; n = 42) and inland waterways (6.2%; n = 15). The majority of respondents were males (64.2%; n = 156) who rescued on average approximately twice as many people in their lifetime (6.5) than female respondents (3.6). Most rescues occurred more than 1 km from lifeguard/lifesaver services (67%; n = 163), but in the presence of others (94.2%; n = 229). The majority of bystander rescuers had water safety training (65.8%; n = 160), self-rated as strong swimmers (68.3%; n = 166), conducted the rescue without help from others (60%; n = 146), did not use a flotation device to assist (63%; n = 153), but were confident in their ability to make the rescue (76.5%; n = 186). However, most considered the situation to be very serious (58%; n = 141) and felt they had saved a life (70.1%; n = 172). With the exception of pools, most bystanders rescued strangers (76.1%; n = 185).While Australia clearly benefits from having a strong water safety culture, there is no clear consensus on the most appropriate actions bystanders should take when confronted with a potential aquatic rescue scenario. In particular, more research is needed to gather information regarding bystander rescues undertaken by those without prior water safety training

Supernova 1987A: Rotation and a Binary Companion

In this paper we provide a possible link between the structure of the bipolar nebula surrounding SN1987A and the properties of its progenitor star. A Wind Blwon Bubble (WBB) scenario is emplyed, in which a fast, tenuous wind from a Blue Supergiant expands into a slow, dense wind, expelled during an earlier Red Supergiant phase. The bipolar shapre develops due to a pole-to-equator density contrast in the slow wind (ie, the slow wind forms a slow torus). We use the Wind Compressed Disk (WCD) model of Bjorkman & Cassinelli (1992) to determine the shape of the slow torus. In the WCD scenario, the shape of the torus is determined by the rotation of the progenitor star. We then use a self-similar semi-analytical method for wind blown bubble evolution to determine the shape of the resulting bipolar nebula. We find that the union of the wind-compressed-disk and bipolar-wind-blown- bubble models allows us to recover the salient properties of SN1987A's circumstellar nebula. In particular, the size, speed and density of SN1987A's inner ring are easily reproduced in our calculations. An exploration of parameter space shows the the red supergiant progenitor must be been rotating at > 0.3 of its breakup speed. We conclude that the progenitor was most likely spun up by a merger with a binary companion. Using a simple model for the binary merger we find that the companion is likely to have had a mass > 0.5 M_sun.Comment: 30 pages, 4 figure

Constructing solutions to the Bj\"orling problem for isothermic surfaces by structure preserving discretization

In this article, we study an analog of the Bj\"orling problem for isothermic surfaces (that are more general than minimal surfaces): given a real analytic curve $\gamma$ in ${\mathbb R}^3$, and two analytic non-vanishing orthogonal vector fields $v$ and $w$ along $\gamma$, find an isothermic surface that is tangent to $\gamma$ and that has $v$ and $w$ as principal directions of curvature. We prove that solutions to that problem can be obtained by constructing a family of discrete isothermic surfaces (in the sense of Bobenko and Pinkall) from data that is sampled along $\gamma$, and passing to the limit of vanishing mesh size. The proof relies on a rephrasing of the Gauss-Codazzi-system as analytic Cauchy problem and an in-depth-analysis of its discretization which is induced from the geometry of discrete isothermic surfaces. The discrete-to-continuous limit is carried out for the Christoffel and the Darboux transformations as well.Comment: 29 pages, some figure