Beyond developable: computational design and fabrication with auxetic materials

We present a computational method for interactive 3D design and rationalization of surfaces via auxetic materials, i.e., flat flexible material that can stretch uniformly up to a certain extent. A key motivation for studying such material is that one can approximate doubly-curved surfaces (such as the sphere) using only flat pieces, making it attractive for fabrication. We physically realize surfaces by introducing cuts into approximately inextensible material such as sheet metal, plastic, or leather. The cutting pattern is modeled as a regular triangular linkage that yields hexagonal openings of spatially-varying radius when stretched. In the same way that isometry is fundamental to modeling developable surfaces, we leverage conformal geometry to understand auxetic design. In particular, we compute a global conformal map with bounded scale factor to initialize an otherwise intractable non-linear optimization. We demonstrate that this global approach can handle non-trivial topology and non-local dependencies inherent in auxetic material. Design studies and physical prototypes are used to illustrate a wide range of possible applications

Three-Omega Thermal-Conductivity Measurements with Curved Heater Geometries

The three-omega method, a powerful technique to measure the thermal conductivity of nanometer-thick films and the interfaces between them, has historically employed straight conductive wires to act as both heaters and thermometers. When investigating stochastically prepared samples such as two-dimensional materials and nanomembranes, residue and excess material can make it difficult to fit the required millimeter-long straight wire on the sample surface. There are currently no available criteria for how diverting three-omega heater wires around obstacles affects the validity of the thermal measurement. In this Letter, we quantify the effect of wire curvature by performing three-omega experiments with a wide range of frequencies using both curved and straight heater geometries on SiO$_2$/Si samples. When the heating wire is curved, we find that the measured Si substrate thermal conductivity changes by only 0.2%. Similarly, we find that wire curvature has no significant effect on the determination of the thermal resistance of a $\sim$65 nm SiO$_2$ layer, even for the sharpest corners considered here, for which the largest measured ratio of the thermal penetration depth of the applied thermal wave to radius of curvature of the heating wire is 4.3. This result provides useful design criteria for three-omega experiments by setting a lower bound for the maximum ratio of thermal penetration depth to wire radius of curvature.Comment: 4 pages, 3 figure

Long Term Sequela of Pediatric Bladder Reconstruction

Children with refractory neurogenic bladder (NGB) who have failed maximal medical management are presented with options for bladder reconstruction. It is critical to understand the long-term sequela of bladder augmentation and bladder neck reconstruction to properly counsel families regarding these procedures. Benefits may include preservation of renal function, continence, reduced risk of renal-related mortality, and potential improvements in quality of life (QOL). However, these advantages must be balanced with the risks of bladder calculi, perforation, need for additional surgery, acid/base disturbances, vitamin B12 deficiency, and malignancy. Therefore, careful patient selection and preoperative counseling are paramount for those undergoing bladder reconstruction which includes intestinal bladder augmentation, as these patients require lifelong vigilant follow-up

Is It Time to Give Athletes a Voice in the Dissemination Strategies of Concussion-Related Information? Exploratory Examination of 2444 Adolescent Athletes

Objective: The objective of the research was to screen male and female adolescent athletes on their concussion educational histories and preferred future methods of education in terms of educational messenger, modality, and concussion-related areas of interest. Design: Cross-sectional survey. Setting: Examination setting within the classroom. Participants: Adolescent male (n = 1854) and female (n = 590) athletes aged 12 to 18 years. Main outcome measures: To explore the concussion educational histories and preferred future methods of education in Irish male and female adolescent athletes. Results: 19.7% (n = 482) of the sample received education in the past 12 months. Male athletes had a significantly higher rate of previous education than female athletes (41% vs 17%). The methods used in previous educational interventions are failing to match the interests of the athletes. Sex played a significant role in the preferred educational methods, as male and female athletes had significant differences in their choice of educational messenger, modality, and concussion-related areas of interest. Conclusions: The current disparity in previous concussion education rates between male and female adolescent athletes should be addressed. Forthcoming research should explore the efficacy of tailoring knowledge translation strategies to match the specific needs of the recipient

Improvement in time to treatment, but not time to diagnosis, in patients with mucopolysaccharidosis type I

Objective Early diagnosis and treatment initiation are important factors for successful treatment of mucopolysaccharidosis type I (MPS I). The purpose of this observational study was to assess whether age at diagnosis and time to first treatment for individuals with MPS I have improved over the last 15 years. Study design Data from the MPS I Registry (NCT00144794) for individuals with attenuated or severe disease who initiated therapy with laronidase enzyme replacement therapy (ERT) and/or hematopoietic stem cell transplantation (HSCT) between 1 January 2003 and 31 December 2017 were included. Results Data were available for 740 individuals with attenuated (n=291) or severe (n=424) MPS I (unknown n=25). Median age at diagnosis for attenuated disease did not change over time and ranged between 4.5 and 6 years of age while the median duration from diagnosis to first ERT decreased from 5.6 years before/during 2004 to 2.4 months in 2014–2017. For severe MPS I treated with HSCT, median age at diagnosis was less than 1 year and median time to first treatment was less than 3 months throughout the 15-year observation period. Conclusions Times to diagnosis and HSCT initiation for individuals with severe MPS I were consistent over time. For individuals with attenuated MPS I, the time to ERT initiation after diagnosis has improved substantially in the last 15 years, but median age at diagnosis has not improved. Efforts to improve early diagnosis in attenuated MPS I are needed to ensure that patients receive appropriate treatment at the optimal time

Relating PH and Ion Release from Ga2O3-Na 2O-CaO-ZnO-SiO2 Bioactive Glasses

Three glasses were designed for this study, including one Ga-free glass (Control), and two Ga-containing glasses (TGa-1, TGa-2). In the Ga-containing glasses, Ga2O3 is included at the expense of ZnO. This study focuses on the relation between pH and ion concentration present in solution in which these bioactive glasses have been submerged for periods of 1, 7, and 14 days. © 2013 IEEE

The Structural Characterization of Ga 2O 3-Na 2O-CaO-ZnO-SiO 2 Bioactive Glasses

The characterization of bioactive glasses in which zinc (Zn) has been incrementally replaced by gallium (Ga). © 2012 IEEE