The pore size of polycaprolactone scaffolds has limited influence on bone regeneration in an in vivo model

Bone tissue engineering scaffolds should be designed to optimize mass transport, cell migration, and mechanical integrity to facilitate and enhance new bone growth. Although many scaffold parameters could be modified to fulfill these requirements, pore size is an important scaffold characteristic that can be rigorously controlled with indirect solid freeform fabrication. We explored the effect of pore size on bone regeneration and scaffold mechanical properties using polycaprolactone (PCL) scaffolds designed with interconnected, cylindrical orthogonal pores. Three scaffold designs with unique microarchitectures were fabricated, having pore sizes of 350, 550, or 800 Μm. Bone morphogenetic protein-7 transduced human gingival fibroblasts were suspended in fibrin gel, seeded into scaffolds, and implanted subcutaneously in immuno-compromised mice for 4 or 8 weeks. We found that (1) modulus and peak stress of the scaffold/bone constructs depended on pore size and porosity at 4 weeks but not at 8 weeks, (2) bone growth inside pores depended on pore size at 4 weeks but not at 8 weeks, and (3) the length of implantation time had a limited effect on scaffold/bone construct properties. In conclusion, pore sizes between 350 and 800 Μm play a limited role in bone regeneration in this tissue engineering model. Therefore, it may be advantageous to explore the effects of other scaffold structural properties, such as pore shape, pore interconnectivity, or scaffold permeability, on bone regeneration when designing PCL scaffolds for bone tissue engineering. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res, 2010Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/64538/1/32381_ftp.pd

Habitat Characteristics of Northern Bobwhite Quail-Hunting Party Encounters: A Landscape Perspective

Landcover data and bobwhite hunting records were used to assess both hunter habitat preferences and the frequency of northern bobwhite encounters by hunting parties in relation to habitat composition during the 1994-1995 and 1995-1996 hunting seasons at the Joseph W. Jones Ecological Research Center in southern Georgia. Patterns of habitat use by hunters, and the frequency of bobwhite encounters varied within and between years, depending on habitat quality, food availability, and other factors. Landscape-scale analyses of standardized bobwhite covey densities (based on coveys pointed in the field) and habitat composition and configuration for the 1994-1995 hunting season revealed that bobwhite densities were: (1) positively associated with the overall percentage agriculture and food plot habitat (reaching a maximum at 30-35% agriculture); and (2) positively associated with edge complexity, and positively associated with agricultural mean patch size [reaching a maximum at 2-3 hectares (5-6 acres)]. Consequently, larger food plots may be more important for increasing bobwhite encounter rates than numerous very small food plots [ \u3c 0.1 hectares (0.25 acres)]. Results of this, and related ongoing studies, have important implications for both landscape design and multiple use resource management. activities in the context of northern bobwhite habitat management in southern upland pine forest ecosystems

Microwave Kinetic Inductance Detector (MKID) Camera Testing for Submillimeter Astronomy

Developing kilopixel focal planes for incoherent submm- and mm-wave detectors remains challenging due to either the large hardware overhead or the complexity of multiplexing standard detectors. Microwave kinetic inductance detectors (MKIDs) provide a efficient means to produce fully lithographic background-limited kilopixel focal planes. We are constructing an MKID-based camera for the Caltech Submillimeter Observatory with 576 spatial pixels each simultaneously sensitive in 4 bands at 230, 300, 350, and 400 GHz. The novelty of MKIDs has required us to develop new techniques for detector characterization. We have measured quasiparticle lifetimes and resonator Qs for detector bath temperatures between 200 mK and 400 mK. Equivalent lifetime measurements were made by coupling energy into the resonators either optically or by driving the third harmonic of the resonator. To determine optical loading, we use both lifetime and internal Q measurements, which range between 15,000 and 30,000 for our resonators. Spectral bandpass measurements confirm the placement of the 230 and 350 GHz bands. Additionally, beam maps measurements conform to expectations. The same device design has been characterized on both sapphire and silicon substrates, and for different detector geometries. We also report on the incorporation of new shielding to reduce detector sensitivity to local magnetic fields

Modulating signaling networks by CRISPR/Cas9-mediated transposable element insertion

In a recent past, transposable elements (TEs) were referred to as selfish genetic components only capable of copying themselves with the aim of increasing the odds of being inherited. Nonetheless, TEs have been initially proposed as positive control elements acting in synergy with the host. Nowadays, it is well known that TE movement into host genome comprises an important evolutionary mechanism capable of increasing the adaptive fitness. As insights into TE functioning are increasing day to day, the manipulation of transposition has raised an interesting possibility of setting the host functions, although the lack of appropriate genome engineering tools has unpaved it. Fortunately, the emergence of genome editing technologies based on programmable nucleases, and especially the arrival of a multipurpose RNA-guided Cas9 endonuclease system, has made it possible to reconsider this challenge. For such purpose, a particular type of transposons referred to as miniature inverted-repeat transposable elements (MITEs) has shown a series of interesting characteristics for designing functional drivers. Here, recent insights into MITE elements and versatile RNA-guided CRISPR/Cas9 genome engineering system are given to understand how to deploy the potential of TEs for control of the host transcriptional activity.Fil: Vaschetto, Luis Maria Benjamin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Diversidad y Ecología Animal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto de Diversidad y Ecología Animal; Argentina. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Cátedra de Diversidad Animal I; Argentin

Electromagnetic design for SuperSpec: a lithographically-patterned millimetre-wave spectrograph

SuperSpec is an innovative, fully planar, compact spectrograph for mm/sub-mm astronomy. SuperSpec is based on a superconducting filter-bank consisting of a series of planar half-wavelength filters to divide up the incoming, broadband radiation. The power in each filter is then coupled into titanium nitride lumped element kinetic inductance detectors, facilitating the read out of a large number of filter elements. We will present electromagnetic simulations of the different components that will make up an R = 700 prototype instrument. Based on these simulations, we discuss optimisation of the coupling between the antenna, transmission line, filters and detectors

Scaffold Translation: Barriers Between Concept and Clinic

Translation of scaffold-based bone tissue engineering (BTE) therapies to clinical use remains, bluntly, a failure. This dearth of translated tissue engineering therapies (including scaffolds) remains despite 25 years of research, research funding totaling hundreds of millions of dollars, over 12,000 papers on BTE and over 2000 papers on BTE scaffolds alone in the past 10 years (PubMed search). Enabling scaffold translation requires first an understanding of the challenges, and second, addressing the complete range of these challenges. There are the obvious technical challenges of designing, manufacturing, and functionalizing scaffolds to fill the Form, Fixation, Function, and Formation needs of bone defect repair. However, these technical solutions should be targeted to specific clinical indications (e.g., mandibular defects, spine fusion, long bone defects, etc.). Further, technical solutions should also address business challenges, including the need to obtain regulatory approval, meet specific market needs, and obtain private investment to develop products, again for specific clinical indications. Finally, these business and technical challenges present a much different model than the typical research paradigm, presenting the field with philosophical challenges in terms of publishing and funding priorities that should be addressed as well. In this article, we review in detail the technical, business, and philosophical barriers of translating scaffolds from Concept to Clinic. We argue that envisioning and engineering scaffolds as modular systems with a sliding scale of complexity offers the best path to addressing these translational challenges.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90495/1/ten-2Eteb-2E2011-2E0251.pd

Low Frequency (100-600 MHz) Searches with Axion Cavity Haloscopes

We investigate reentrant and dielectric loaded cavities for the purpose of extending the range of axion cavity haloscopes to lower masses, below the range where the Axion Dark Matter eXperiment (ADMX) has already searched. Reentrant and dielectric loaded cavities were simulated numerically to calculate and optimize their form factors and quality factors. A prototype reentrant cavity was built and its measured properties were compared with the simulations. We estimate the sensitivity of axion dark matter searches using reentrant and dielectric loaded cavities inserted in the existing ADMX magnet at the University of Washington and a large magnet being installed at Fermilab.Comment: 33 pages, 24 figure