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Multi-Nozzle Biopolymer Deposition for Freeform Fabrication of Tissue Constructs
Advanced freeform fabrication techniques have been recently used for the construction of tissue
scaffolds because of the process repeatability and capability of high accuracy in fabrication
resolution at the macro and micro scales. Among many applicable tissue scaffolding materials,
polymeric materials have unique properties in terms of the biocompatibility and degradation, and
have thus been widely utilized in tissue engineering applications. Hydrogels, such as alginate,
has been one of the most important polymer scaffolding materials because of its biocompatibility
and internal structure similarity to that of the extracellular matrix of many tissues, and its
relatively moderate processing. Three-dimensional deposition has been an entreating freeform
fabrication method of biopolymer and particularly hydrogel scaffolds because of its readiness to
deposit fluids at ambient temperatures. This paper presents a recent development of biopolymer
deposition based freeform fabrication for 3-diemnsinal tissue scaffolds. The system
configuration of multi-nozzles used in the deposition of sodium alginate solutions and Poly-?-
Caprolactone (PCL) are described. Studies on polymer deposition feasibility and structural
formability are conducted, and the preliminary results are presented.Mechanical Engineerin
Zeeman-limited Superconductivity in Crystalline Al Films
We report the evolution of the Zeeman-mediated superconducting phase diagram
(PD) in ultra-thin crystalline Al films. Parallel critical field measurements,
down to 50 mK, were made across the superconducting tricritical point of films
ranging in thickness from 7 ML to 30 ML. The resulting phase boundaries were
compared with the quasi-classical theory of a Zeeman-mediated transition
between a homogeneous BCS condensate and a spin polarized Fermi liquid. Films
thicker than 20 ML showed good agreement with theory, but thinner films
exhibited an anomalous PD that cannot be reconciled within a homogeneous BCS
framework.Comment: 8 pages, 9 figure
Helices at Interfaces
Helically coiled filaments are a frequent motif in nature. In situations
commonly encountered in experiments coiled helices are squeezed flat onto two
dimensional surfaces. Under such 2-D confinement helices form "squeelices" -
peculiar squeezed conformations often resembling looped waves, spirals or
circles. Using theory and Monte-Carlo simulations we illuminate here the
mechanics and the unusual statistical mechanics of confined helices and show
that their fluctuations can be understood in terms of moving and interacting
discrete particle-like entities - the "twist-kinks". We show that confined
filaments can thermally switch between discrete topological twist quantized
states, with some of the states exhibiting dramatically enhanced
circularization probability while others displaying surprising
hyperflexibility
A DC Programming Approach for Solving Multicast Network Design Problems via the Nesterov Smoothing Technique
This paper continues our effort initiated in [9] to study Multicast
Communication Networks, modeled as bilevel hierarchical clustering problems, by
using mathematical optimization techniques. Given a finite number of nodes, we
consider two different models of multicast networks by identifying a certain
number of nodes as cluster centers, and at the same time, locating a particular
node that serves as a total center so as to minimize the total transportation
cost through the network. The fact that the cluster centers and the total
center have to be among the given nodes makes this problem a discrete
optimization problem. Our approach is to reformulate the discrete problem as a
continuous one and to apply Nesterov smoothing approximation technique on the
Minkowski gauges that are used as distance measures. This approach enables us
to propose two implementable DCA-based algorithms for solving the problems.
Numerical results and practical applications are provided to illustrate our
approach
Decision Support Systems in Australian Agriculture: State of the Art and Future Development
This paper reports and discusses the results of a survey conducted with experts working in the field of decision support systems (DSS) in Australian agriculture. It also reviews the literature on DSS in the light of these experts' responses. The findings from this survey have consolidated our understanding of the current state of DSS in Australian agriculture. The uptake of DSS by farmers has been slow and various issues said to be contributing to this include fear of using computers, time constraints, poor marketing, complexity, lack of local relevance, lack of end-user involvement, and mismatched objectives between developers and users. The future prospect for the development of DSS was generally regarded to be poor. Never-the-less, the authors believe that new DSS which embrace the suggested criteria could be widely accepted by farmers. These criteria mean that to be widely used by farmers, any successful DSS needs to address widespread problems: they need to be location specific, and gain strong support from initial users. They also need to be simple to use, relevant, effective, low cost, and user friendly and it is most likely that farmers would have been involved in their development. We believe that farmers' personalities, and their attitudes towards risk management and decision making, will influence the pattern of adoption of DSS in Australian agriculture while the intergenerational change that is occurring in the management of Australian farms is a positive factor that may encourage more widespread use of these tools.DSS, farmers' decision-making, expert opinion, management decisions, Farm Management, D7, D8, Q12, Q13, Q16,
A new puzzle for random interaction
We continue a series of numerical experiments on many-body systems with
random two-body interactions, by examining correlations in ratios in excitation
energies of yrast = 0, 2, 4, 6, 8 states. Previous studies, limited only to
= 0,2,4 states, had shown strong correlations in boson systems but not
fermion systems. By including states and considering different
scatter plots, strong and realistic correlations appear in both boson and
fermion systems. Such correlations are a challenge to explanations of random
interactions.Comment: 4 pages, 4 figure
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