262 research outputs found
Recommended from our members
A Personal Dead Reckoning RFID Waypoint Updated System for Footstep Level Resolution Path Tracking to Enable Research Into Early Diagnosis of Alzheimer’s
The problem of footstep level resolution indoor path tracking and gait velocity
lacks a good solution. The current solutions are either prohibitively expensive [4],
extremely invasive to deploy [1], or too inaccurate to achieve the sub meter level
resolution required to track foot paths. By combining existing pedestrian dead
reckoning (PDR) using an inertial measurement unit (IMU) techniques with
radio frequency identification (RFID) location updates, one can solve the
problem of indoor path tracking. RFID tags placed in the building act as
waypoints to correct the error that accumulates over time with PDR, thus
yielding a system that can be used for arbitrary amounts of time with a
resolution high enough to track individual footsteps
Investigating the influence of the core material on the mechanical performance of a nitinol wire wrapped helical auxetic yarn.
Helical Auxetic Yarns (HAYs) can be used in a variety of applications, from healthcare to blast and impact resistance. This work focuses on the effect of the use of different core materials (e.g. rubber, polyurethane, polytetrafluoroethylene/teflon, polypropylene, polyetheretherketone, polycarbonate, acetal) with a nitinol wire wrap component on the maximum Negative Poisson Ratio (NPR) produced, and therefore the auxetic performance of Helical Auxetic Yarns (HAYs). From the analytical model, it was found that an acetal core produced the largest NPR when compared to the other six materials. The trend obtained from the experimental tensile tests (validation) correlated closely with the theoretical predictions of the NPR as axial strain was increased. The experimental method presented a maximum NPR at an average axial strain of 0.148, which was close to the strain of 0.155 predicted by theory. However, the maximum experimental NPR was significantly lower than that predicted by the analytical model
Disruption of Dcp1 leads to a Dcp2‐dependent aberrant ribosome profiles in Aspergillus nidulans
There are multiple RNA degradation mechanisms in eukaryotes, key among these is mRNA decapping, which requires the Dcp1-Dcp2 complex. Decapping is involved in various processes including nonsense-mediated decay (NMD), a process by which aberrant transcripts with a premature termination codon are targeted for translational repression and rapid decay. NMD is ubiquitous throughout eukaryotes and the key factors involved are highly conserved, although many differences have evolved. We investigated the role of Aspergillus nidulans decapping factors in NMD and found that they are not required, unlike Saccharomyces cerevisiae. Intriguingly, we also observed that the disruption of one of the decapping factors, Dcp1, leads to an aberrant ribosome profile. Importantly this was not shared by mutations disrupting Dcp2, the catalytic component of the decapping complex. The aberrant profile is associated with the accumulation of a high proportion of 25S rRNA degradation intermediates. We identified the location of three rRNA cleavage sites and show that a mutation targeted to disrupt the catalytic domain of Dcp2 partially suppresses the aberrant profile of Δdcp1 strains. This suggests that in the absence of Dcp1, cleaved ribosomal components accumulate and Dcp2 may be directly involved in mediating these cleavage events. We discuss the implications of this
Managing local coastal stressors to reduce the ecological effects of ocean acidification and warming
Anthropogenic activities have increased the number of stressors acting on ecosystems. When multiple stressors act simultaneously, there is a greater probability of additive, synergistic and antagonistic effects occurring among them. Where additive and synergistic effects occur, managers may yield disproportionately large benefits where they first act upon synergies. Stressors act, however, at different spatial and temporal scales. Global stressors (e.g., ocean acidification and warming) tend to change slowly over long periods of time, although their intensity and effects are contingent on local conditions. On the other hand, local stressors tend to change rapidly over shorter, more defined spatial and temporal scales. Hence, local stressors can be subject to a greater degree of control through local management (e.g., eutrophication and overfishing) while global stressors are characterized by an intrinsic inertia whose effects last for decades, if not centuries. Although the reduction of carbon emissions is an international priority for managing global stressors, it requires international agreements and management applications that take considerable time to develop. Managers, however, may 'buy time' by acting on stressors whose governance is local (e.g., reducing nutrient input) and are known to synergize with global stressors (e.g., enriched CO2). Such local actions may potentially disrupt synergies with the more slowly changing global stressors that can only be reduced over longer time scales. © 2013 by the authors
Phenylethynyl Terminated Imide (PETI) Composites Made by High Temperature VARTM
Fabrication of composite structures using vacuum assisted resin transfer molding (VARTM) is generally more affordable than conventional autoclave techniques. Recent efforts have focused on adapting VARTM for the fabrication of high temperature composites. Due to their low melt viscosity and long melt stability, certain phenylethynyl terminated imides (PETI) can be processed into composites using high temperature VARTM (HT-VARTM). However, one of the disadvantages of the current HT-VARTM resin systems has been the high porosity of the resultant composites. For aerospace applications, a void fraction of <2% is desired. In the current study, two PETI resins, LARC. PETI-330 and LARC. PETI-8 have been used to fabricate test specimens using HT-VARTM. The resins were infused into carbon fiber preforms at 260 C and cured between 316 and 371 C. Photomicrographs of the panels were taken and void contents were determined by acid digestion. Modifications to the thermal cycle used in the laminate fabrication have reduced the void content significantly; typically .3% for carbon fiber biaxially woven fabric and less than 2% for carbon fiber uniaxial fabric. Mechanical properties (short beam shear and flexure) of the panels were determined at both room and elevated temperatures. The results of this work are presented herein. This paper is declared a work of the U.S. Government and is not subject to copyright protection in the United States
Climate Donations Inspired by Evidence-Based Fundraising
Everyone has an opportunity to contribute to climate solutions. To help people engage with this opportunity, it is critical to understand how climate organizations and fundraisers can best communicate with people and win their financial support. In particular, fundraisers often rely on practical skills and anecdotal beliefs at the expense of scientific knowledge. Fundraisers could be motivated to achieve a substantial boost in funding for climate solutions, if there is evidence of the financial gains that science-based fundraising makes available. In this Perspective, we provide a preliminary foray into such evidence. We bring together findings from philanthropic research and climate psychology to identify what factors can help captivate donors. Then, through an experimental study of a charitable appeal for a climate charity, we show how putting these factors into practice may contribute toward an increase in donated money. This provides optimism that evidence-based fundraising can inspire donors to contribute much-needed resources toward climate solutions
High Temperature VARTM of Phenylethynyl Terminated Imides (PETI) Resins
Fabrication of composite structures using vacuum assisted resin transfer molding (VARTM) is generally more affordable than conventional autoclave techniques. Recent efforts have focused on adapting VARTM for the fabrication of high temperature composites. Due to their low melt viscosity and long melt stability, certain phenylethynyl terminated imides (PETI) can be processed into composites using high temperature VARTM (HT-VARTM). However, one of the disadvantages of the current HT-VARTM resin systems has been the high porosity of the resultant composites. For aerospace applications a void fraction of less than 2% is desired. In the current study, two PETI resins, LARCTM PETI-330 and LARCTM PETI-8 have been used to fabricate test specimens using HT-VARTM. The resins were infused into carbon fiber preforms at 260 C and cured between 316 C and 371 C. Modifications to the thermal cycle used in the laminate fabrication have reduced the void content significantly (typically < 3%) for carbon fiber biaxially woven fabric. Photomicrographs of the panels were taken and void contents were determined by acid digestion. For carbon fiber uniaxial fabric, void contents of less than 2% have been obtained using both PETI-8 and PETI-330. Mechanical properties of the panels were determined at both room and elevated temperatures. These include short beam shear and flexure tests. The results of this work are presented herein
- …