5,682 research outputs found
Recommended from our members
The development of a framework for enterprise security architecture and its application in organizations
The main purpose of this study is to develop an enterprise security framework that is based on a comprehensive following the Zachman EA architecture. The enterprise architecture (EA) is a long-term view or blueprint for an organization. It is a very important blueprint for balancing business and IT technology and for adding value to an organization. Security is also an essential dimension for enterprises nowadays. This paper will incorporate the security dimension with the Zachman EA framework, which intends to serve as an enterprise security framework in assisting an organization to successfully and effectively implement security
Software for Modeling Ultrasound Breast Cancer Imaging
Computer-based models are increasingly used in biomedical imaging research to clarify links between anatomical structure, imaging physics, and the information content of medical images. A few three-dimensional breast tissue software models have been developed for mammography simulations to optimize current mammography systems or to test novel systems. It would be beneficial in the development of ultrasound breast imaging to have a similar computational model for simulation. A three-dimensional breast anatomy model with the lobular ducts, periductal and intralobular loose fibrous tissue, interlobular dense fibrous tissue, fat, and skin has been implemented. The parenchymal density of the model can be varied from about 20 to 75% to represent a range of clinically relevant densities. The anatomical model was used as a foundation for a three-dimensional breast tumour model. The tumour model was designed to mimic the ultrasound appearance of features used in tumour classification. Simulated two-dimensional ultrasound images were synthesized from the models using a first-order k-space propagation simulator. Similar to clinical ultrasound images, the simulated images of normal breast tissue exhibited non-Rayleigh speckle in regions of interest consisting of primarily fatty, primarily fibroglandular, and mixed tissue types. The simulated images of tumours reproduced several shape and margin features used in breast tumour diagnosis. The ultrasound wavefront distortion produced in simulations using the anatomical model was evaluated and a second method of modeling wavefront distortion was also proposed in which 10 to 12 irregularly shaped, strongly scattering inclusions were iii superimposed on multiple parallel time-shift screens to create the screen-inclusion model. Simulations of planar pulsed wave propagation through the two proposed models, a conventional parallel time-shift screen model, and digitized breast tissue specimens were compared. The anatomical model and screen-inclusion model were able to produce arrival-time fluctuation and energy-level fluctuation characteristics comparable to the digitized tissue specimens that the parallel-screen model was unable to reproduce. This software is expected to be valuable for imaging simulations that require accurate and detailed representation of the ultrasound characteristics of breast tumours
Edge chirality determination of graphene by Raman spectroscopy
Raman imaging on the edges of single layer micromechanical cleavage graphene
(MCG) was carried out. The intensity of disorder-induced Raman feature (D band
at ~1350 cm-1) was found to be correlated to the edge chirality: it is stronger
at the armchair edge and weaker at the zigzag edge. This shows that Raman
spectroscopy is a reliable and practical method to identify the chirality of
graphene edge and to help in determination of the crystal orientation. The
determination of graphene chirality is critically important for fundamental
study as well as for applications.Comment: 14 pages, 3 figures, 1 tabl
Marker-less motion capture for biomechanical analysis using the Kinect sensor
Motion capture systems are gaining more and more importance in different fields of
research. In the field of biomechanics, marker-based systems have always been used as
an accurate and precise method to capture motion. However, attaching markers on the
subject is a time-consuming and laborious method. As a consequence, this problem has
given rise to a new concept of motion capture based on marker-less systems. By means
of these systems, motion can be recorded without attaching any markers to the skin of the
subject and capturing colour-depth data of the subject in movement. The current thesis
has researched on marker-less motion capture using the Kinect sensor, and has
compared the two motion capture systems, marker-based and marker-less, by analysing
the results of several captured motions. In this thesis, two takes have been recorded and
only motion of the pelvis and lower limb segments have been analysed. The methodology
has consisted of capturing the motions using the marker-based and marker-less systems
simultaneously and then processing the data by using specific software. At the end, the
angles of hip flexion, hip adduction, knee and ankle obtained through the two systems
have been compared. In order to obtain the three-dimensional joint angles using the
marker-less system, a new software named iPi Soft has been introduced to process the
data from the Kinect sensor. Finally, the results of two systems have been compared and
thoroughly discussed, so as to assess the accuracy of the Kinect system
Mechanical characterization of Polymer matrix composites produced by 3D printing
In the last decade, additive manufacturing (AM) technology has undergone exponential growth and gained more and more importance in the recent research, mainly due to the freedom of creating sophisticated geometries that are impossible to produce using either one or a combination of several alternative production techniques. AM technology has mostly been used for prototyping application during the product design and development phase in many different industrial sectors. However, 3D printed prototypes have limited mechanical properties and the printed parts usually cannot fulfil mechanical requirements for functional applications. As a consequence, this problem has given rise to a new concept of 3D printing technique based on adding fibers to the polymeric material matrix. By means of this technique, the mechanical properties of the printed parts can be enhanced. The current thesis has researched in carbon fiber reinforcement for nylon specimens printed by the Mark One printer from Markforged. The carbon reinforced specimens were compared with pure nylon specimens by means of the results obtained from tensile and flexural tests. Nylon and carbon reinforced nylon specimens were printed for both tensile and flexural tests. The methodology consisted of obtaining the specimens by 3D printer, do the mechanical characterization and treat the data obtained. In order to print the specimens and configure the printing options, a software named Eiger was used. The results of the mechanical characterization of carbon reinforced nylon and pure nylon specimens were compared and thoroughly discussed, so as to assess the improvement of the carbon reinforced nylon specimensâ mechanical properties
The Role of Gut Microbiota Urease in the Host With Liver Disease
Significant metabolic interactions exist between the gut microbiota and the mammalian host, one prime example of which is nitrogen metabolism. In the colon, bacterial urease hydrolyzes host-derived urea into carbon dioxide and ammonia. Colonic ammonia can subsequently be absorbed by the host or utilized by the gut microbiota for additional nitrogen metabolism. In patients with liver disease such as cirrhosis and congenital urea cycle disorders, hepatic abnormalities prevent the normal processing of ammonia, leading to hyperammonemia and hepatic encephalopathy (HE). Although circulating ammonia levels are correlated with damage to the central nervous system, the pathogenesis of HE is complex and not fully elucidated, hindering progress in treatment. Current treatment options including antibiotics, lactulose, and a low protein diet (LPD) are complicated by issues such as side effects, concerns of safety and efficacy in long-term use, and poor adherence. Our goal is to develop a safe, durable, and efficacious treatment for HE through the inoculation of a urease-free bacterial consortium. We show that we are able to engineer the gut microbiota to reduce fecal urease activity and ammonia levels in mice. Depletion of the endogenous gut microbiota
followed by transplantation with Altered Schaedler Flora (ASF), a defined consortium of eight murine gut commensal bacteria with minimal urease gene content, established a persistent new community that exhibited long-term reduction in fecal urease activity and fecal ammonia production. ASF transplantation was associated with a decrease in morbidity and mortality in the thioacetamide (TAA) murine model of hepatic injury and fibrosis. Although the ASF consortium demonstrated reduced resilience in response to dietary stress, ASF transplantation led to further reductions in fecal ammonia on a LPD without exacerbating host metabolic dysfunction. These findings point to the potential use of a human urease-free bacterial consortium to alter clinical management and outcome in HE. Furthermore, they provide proof of concept that microbiota transplantation with a defined microbial consortium can lead to durable metabolic changes with therapeutic utility
The Complex Effects of Picturebooks on English as a Foreign Language Reading
While effects of picturebooks on reading were examined in higher grades (e.g., high school students) (Ajayi, 2009), little is known about the emerging English as Foreign Language (EFL) Kindergartens to 4th graders (i.e., K-4) students in China. Language institutes are critical phenomena for EFL K-4 education in China (Shi, 2019). Aiming to test the hypothesis that picturebooks have positive effects for reading, this study adopted within-subjects and between-subjects design to examine the effects of picturebooks on EFL reading comprehension of K-4 students in a language institute in China. Thirty-two participants were assigned into two groups to complete multiple choice and ordering tasks. The results showed that students reading with picturebooks outperformed in the two tasks than those who did not, especially on answering literal questions. With pedagogical implication as a goal, we suggest that EFL teachers need to (1) provide scaffoldings in class such as activating studentsâ prior knowledge, (2) make connections to studentsâ experience in the reading process. (3) select picturebooks considering the complex relationship between pictures and texts
Preparation and Characterization of PMMA and its Derivative via RAFT Technique in the Presence of DisulïŹde as a Source of Chain Transfer Agent
Poly(methyl methacrylate) (PMMA) were synthesized by using chain transfer agents(CTA), S-1-Dodecyl-SâČ-(α,αâČ-dimethyl-α-acetic acid) trithiocarbonate (MTTCD), S,SâČ-bis (2-hydroxyethyl-2âČ-dimethylacrylate) trithiocarbonate (BDATC), 2-cyanoprop-2-yl dithiobenzoate (CPDB) respectively, through the reversible addition fragmentation chain transfer (RAFT) polymerization under a range of synthesis conditions. The results indicated that the structure of the end-group of RAFT agents had signiïŹcant effects on the ability to control polymerization. Compared with MTTCD and CPDB, BDATC can provide better control over the relative molecular mass, distribution and polymerization of PMMA. The derived well-controlled block copolymer PMMA-b-PDMAEMA and PMMA-b-PDMAEA were also successfully prepared by using N, N-dimethylaminoethy acrylate (DMAEA) or N, N-dimethylaminoethyl methacrylate (DMAEMA) as the second monomer. The chemical composition and structure of the products were characterized by FTIR, 1HNMR, XRD and DSC. CO2 and N2 permeation performance of the PMMA-b-PDMAEA/PS composite membranes were tested at different pressure. The results showed that the resulted composited membrane had a CO2 permeation rate of 3.68Ă10-5cm3 (STP) cm-2s-1cmHg-1, a N2 permeation rate of 1.78Ă10-7 cm3 (STP) cm-2s-1cmHg-1 and an ideal CO2/ N2 selectivity of 206.6 at a feed gas pressure of 7.6 cmHg and 30 oC
- âŠ