Explore the vast range of titles available.

Ultrasound elastography has been available on most modern systems; however, the implementation of quality processes tends to be ad hoc. It is essential for a medical physicist to benchmark elastography measurements on each system and track them over time, especially after major software upgrades or repairs. This study aims to establish baseline data using phantoms and monitor them for quality assurance in elastography. In this paper, we utilized two phantoms: a set of cylinders, each with a composite material with varying Young’s moduli, and an anthropomorphic abdominal phantom containing a liver modeled to represent early-stage fibrosis. These phantoms were imaged using three ultrasound manufacturers’ elastography functions with either point or 2D elastography. The abdominal phantom was also imaged using magnetic resonance elastography (MRE) as it is recognized as the non-invasive gold standard for staging liver fibrosis. The scaling factor was determined based on the data acquired using MR and US elastography from the same vendor. The ultrasound elastography measurements showed inconsistency between different manufacturers, but within the same manufacturer, the measurements showed high repeatability. In conclusion, we have established baseline data for quality assurance procedures and specified the criteria for the acceptable range in liver fibrosis phantoms during routine testing.

Tactile sensing is the current challenge in robotics and object manipulation by machines. The robot’s agile interaction with the environment requires pressure sensors to detect not only location and value, but also touch direction. The paper presents a new, two-layer construction of artificial robotic skin, which allows measuring the location, value, and direction of pressure from external force. The main advantages of the proposed solution are its low cost of implementation based on two FSR (Force Sensitive Resistor) matrices and real-time operation thanks to direction detection using fast matching algorithms. The main contribution is the idea of detecting the pressure direction by determining the shift between the pressure maps of the skin’s upper and lower layers. The pressure map of each layer is treated as an image and registered using a phase correlation (POC–Phase Only Correlation) method. The use of the developed device can be very wide. For example, in the field of cooperative robots, it can lead to the improvement of human machine interfaces and increased security of human–machine cooperation. The proposed construction can help meet the increasing requirements for robots in cooperation with humans, but also enable agile manipulation of objects from their surroundings.

Resistance spot welding (RSW) involves joining of contacting surfaces by heat generated by resistance to electric current . The process is swift and finds demand in automobile industries for mass production. In spite of all the assets of the process, it yields a poor quality welds and inferior weld strength at the inner region of the joint interface. This may be improved by accurate setting of control parameters. The objective of this study is to determine the effect of various control parameters like electrode tip diameter, welding current, and heating cycle on the nugget size and tensile shear strength of dissimilar metal spot welding of 2-mm-thick AISI 316L austenitic stainless steel and 2205 Duplex Stainless Steel sheets. The Taguchi’s L27 orthogonal array (OA) design is selected to conduct the experimental spot welding trials on the dissimilar materials. Subsequently, the specimens are examined usinganalysis of variance (ANOVA) technique to customize optimal parameter setting to obtain high tensile strength and favorable weld quality characteristics. The results reveal that welding current is the most dictating factor to achieve highest tensile strength with superior weld quality. Also, weld samples are prepared for metallographic examination from cross section areas of resistance spot welds to examine microstructure changes and ferrite content measurement in different regions of weld nugget. The microstructure examination shows that the weld nugget consists of ferrite and austenite and ferrite and there is no precipitate of detrimental phases in the weldment.

Innovation processes in multinational enterprises (MNE) are largely context specific, and carried out at the subsidiary level. Therefore, corporate headquarters (HQ) involvement in these processes becomes a major issue. A typical assumption in international business (IB) theory is that HQ, based on its own knowledge, makes rational choices about its own involvement. However, according to some studies, HQ involvement can be assumed to be less rational, in the sense that it reflects not HQ knowledge but the normative expectations associated with the role of HQ as top manager. The purpose of this paper is to contrast these two perspectives by exploring their implications regarding the relationship between HQ knowledge about and HQ involvement in innovation processes at the subsidiary level, and regarding the impact of this potential involvement on innovation processes performance. The analysis results in six propositions and an illustrative case. Our contribution to IB research is primarily theoretical: we bring to the scene an alternative approach - the sheer ignorance perspective - with the potential to explain the behavior of key actors in the MNE. We argue, however, that the theoretical conflict between the two perspectives should be addressed by empirical research. We conclude with suggestions for the directions such research might take.

Third-degree burn injuries pose a significant health threat. Safer, easier-to-use, and more effective techniques are urgently needed for their treatment. We hypothesized that covalently bonded conjugates of fatty acids and tripeptides can form wound-compatible hydrogels that can accelerate healing. We first designed conjugated structures as fatty acid–aminoacid1–amonoacid2–aspartate amphiphiles (Cn acid–AA1–AA2–D), which were potentially capable of self-assembling into hydrogels according to the structure and properties of each moiety. We then generated 14 novel conjugates based on this design by using two Fmoc/tBu solid-phase peptide synthesis techniques; we verified their structures and purities through liquid chromatography with tandem mass spectrometry and nuclear magnetic resonance spectroscopy. Of them, 13 conjugates formed hydrogels at low concentrations (≥0.25% w/v), but C8 acid-ILD-NH2 showed the best hydrogelation and was investigated further. Scanning electron microscopy revealed that C8 acid-ILD-NH2 formed fibrous network structures and rapidly formed hydrogels that were stable in phosphate-buffered saline (pH 2–8, 37 °C), a typical pathophysiological condition. Injection and rheological studies revealed that the hydrogels manifested important wound treatment properties, including injectability, shear thinning, rapid re-gelation, and wound-compatible mechanics (e.g., moduli G″ and G′, ~0.5–15 kPa). The C8 acid-ILD-NH2(2) hydrogel markedly accelerated the healing of third-degree burn wounds on C57BL/6J mice. Taken together, our findings demonstrated the potential of the Cn fatty acid–AA1–AA2–D molecular template to form hydrogels capable of promoting the wound healing of third-degree burns.

A parametric numerical study of wind turbine blade profile surface roughness has been carried out to investigate its effects on boundary layer characteristics and accreted ice growth. DU96-W-180 blade profile is used in this paper. Multiphase numerical analysis has been performed at glaze ice conditions for three different surface roughness values: Shin et al. surface roughness model and two specific roughness values (0.03m and 0.0003m). Study shows that surface roughness considerably effects the shear stresses as well as heat fluxes, which results a variation of ice accretion in rate and shape. Results show that accreted ice mass and ice thickness increases with the increase of surface roughness.

Results from an experimental investigation aimed at evaluating the effectiveness of steel fiber reinforcement for increasing punching shear strength and ductility in slabs subjected to monotonically increased concentrated load are presented. ten slab-column connections were tested to failure. The main test parameters evaluated were: 1) fiber geometry (hooked or twisted), 2) fiber strength (1100, 1800, or 2300 MPa [160, 260, or 334 ksi]), 3) fiber volume fraction (1% or 1.5%), and 4) slab tension reinforcement ratio (0.56% or 0.83% in each principal direction). Out of the fiberreinforced concretes (or mortar) evaluated, those reinforced with a 1.5% volume fraction of either regular strength (1100 MPa [160 ksi]) or high-strength (2300 MPa [334 ksi]) hooked steel fibers led to the best performance in terms of punching shear strength and deformation capacity. These two fiber-reinforced concretes (FRCs) were therefore selected for further evaluation in connections subjected to lateral displacement reversals, as described in the companion paper.

Background In our earlier study on the functional limits of the aneurysmal aortic root we determined the pig root is susceptible to failure at high aortic pressures levels. We established a pig rupture model using cardiopulmonary bypass to determine the most susceptible region of the aortic root under the highest pressures achievable using continuous flow, and what changes occur in these regions on a macroscopic and histological level. This information may help guide clinical management of aortic root and ascending aorta pathology. Methods Five pigs underwent 4D flow MRI imaging pre surgery to determine vasopressor induced wall sheer stress and flow parameters. All pigs were then placed on cardiopulmonary bypass (CPB) via median sternotomy, and maximal aortic root and ascending aorta flows were initiated until rupture or failure, to determine the most susceptible region of the aorta. The heart was explanted and analysed histologically to determine if histological changes mirror the macroscopic observations. Results The magnetic resonance imaging (MRI) aortic flow and wall sheer stress (WSS) increased significantly in all regions of the aorta, and the median maximal pressures obtained during cardiopulmonary bypass was 497 mmHg and median maximal flows was 3.96 L/m. The area of failure in all experiments was the non-coronary cusp of the aortic valve. Collagen and elastin composition (%) was greatest in the proximal regions of the aorta. Collagen I and III showed greatest content in the inner aortic root and ascending aorta regions. Conclusions This unique porcine model shows that the aortic root is most susceptible to failure at high continuous aortic pressures, supported histologically by different changes in collagen content and subtypes in the aortic root. With further analysis, this information could guide management of the aortic root in disease.

Habitat degradation, organismal needs, and other effects influencing freshwater mussel declines have been subject to intense focus by conservationists for the last thirty plus years. While researchers have studied the physical habitat requirements and needs of mussels in small- to medium-sized rivers with variable levels of success, less research has been conducted on mussel habitat in larger non-wadeable rivers, especially at the reach scale, where core flow environmental conditions provide and maintain habitat for freshwater mussels. We designed a quasi-experimental observational field study to examine seven hydrologic energy and material variables laterally and longitudinally at Current and Extirpated mussel bed habitat reaches in lower White River, Arkansas, a large non-wadeable, sand-bed-material-dominated river. As expected, lateral and longitudinal hydrologic variable differences were identified within a reach. Mean velocity, bed velocity, the Froude number, and stream power were all significantly lower at Current mussel bed habitat stations within a sampling reach. Energy regime differences in shear stress and, marginally, stream power were higher at Extirpated mussel bed habitat reaches. Several factors emerged as important to mussel habitat in the White River. First, bed velocity warrants further exploration in terms of both flow strength and flow direction. Second, bedload appears to be the primary contributor to mussel habitat but requires additional exploration within the context of core and secondary flow pathway interactions. The combined empirical evidence from our study supports the flow refugium concept identified for mussel habitats in smaller systems but expands the concept to large non-wadeable streams and includes reach-scale refuge from sediment transport conditions.

The SHEER database brings together a large amount of data of various types: interdisciplinary site data from seven independent episodes, research data and those for the project results dissemination process. This concerns mainly shale gas exploitation test sites, processing procedures, results of data interpretation and recommendations. The smart SHEER database harmonizes data from different fields (geophysical, geochemical, geological, technological, etc.), creates and provides access to an advanced database of case studies of environmental impact indicators associated with shale gas exploitation and exploration, which previously did not exist. A unique component of the SHEER database comes from the monitoring activity performed during the project in one active shale gas exploration and exploitation site at Wysin, Poland, which started from the pre-operational phase. The SHEER database is capable of the adoption of new data such as results of other Work Packages and has developed an over-arching structure for higher-level integration.