University of Memphis

About: University of Memphis is a education organization based out in Memphis, Tennessee, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 7710 authors who have published 20082 publications receiving 611618 citations. The organization is also known as: U of M.

The use of nanoindentation for characterizing the properties of mineralized hard tissues: state-of-the art review

Abstract: The use of nanoindentation to determine nanomechanical properties of mineralized tissues has been investigated extensively. A detailed, critical, and comprehensive review of this literature is the subject of the present work. After stating the motivation for the review, a succinct presentation of the challenges, advantages, and disadvantages of the various quasi-static nanoindentation test methods (to obtain elastic modulus, E, and hardness, H) and dynamic test methods (to obtain storage and loss moduli and/or loss/damping factor) is given in the form of a primer. Explicative summaries of literature reports on various intrinsic and extrinsic factors that significantly influence E and H, followed by 15 suggested topics for future research, are included additionally. This review is designed to present a compact guide to the principles of the nanoindentation technique and to emphasize considerations when determining material properties of mineralized tissues.

Leaf gas exchange and growth of flood-tolerant and flood-sensitive tree species under low soil redox conditions

Abstract: Seedlings of Taxodium distichum L., Quercus lyrata Walt. and Q. falcata var. pagodaefolia Ell. were grown for 22 days in a rhizotron system providing two soil redox potential regimes, +170 mV (low Eh) and +560 mV (high Eh). Leaf chlorophyll concentration and gas exchange, root alcohol dehydrogenase (ADH) activity, root and leaf ethylene production, and growth and biomass partitioning were measured. In response to the low Eh soil treatment, stomatal conductance was reduced in Q. falcata and Q. lyrata but not in T. distichum, whereas net photosynthesis was reduced significantly in all species; however, net photosynthesis in T. distichum began to recover within 2 weeks of treatment initiation. Within each treatment, mean stomatal conductance and net photosynthesis were significantly greater in T. distichum than in the oak species. Leaf chlorophyll concentration was not affected by the soil treatments. All species showed significant reductions in root and leaf dry weights in response to the low Eh soil condition. The low Eh soil treatment resulted in increased root ADH activity and ethylene production in T. distichum, but had no effect on root ADH activity and ethylene production in the oak species.

The continuum of "survivorship": definitional issues in the aftermath of suicide

Abstract: In light of prevailing confusion over the meaning of the term "suicide survivor," we propose a more exact terminology for designating different levels of impact on those left behind by suicide, ranging on a continuum from those exposed to suicide through those who are affected by it and finally to those who are bereaved by suicide in the short- or long-term, as a function of their loss of a close emotional attachment through this tragic form of loss. We briefly note the possible utility of this terminological specificity in promoting more clearly targeted research and intervention efforts, and call for closer investigation of various categories of "survivorship" in future studies.

N-Myc Regulates a Widespread Euchromatic Program in the Human Genome Partially Independent of Its Role as a Classical Transcription Factor

Abstract: Myc proteins have long been modeled to operate strictly as classical gene specific transcription factors, however we find that N-Myc has a robust role in the human genome in regulating global cellular euchromatin including that of intergenic regions. Strikingly, 90–95% of the total genomic euchromatic marks histone H3 acetylated at lysine 9 and methylated at lysine 4 is N-Myc dependent. However, Myc regulation of transcription, even of genes it directly binds and at which it is required for maintenance of active chromatin, is generally weak. Thus, Myc has a much more potent ability to regulate large domains of euchromatin than to influence transcription of individual genes. Overall, Myc regulation of chromatin in the human genome includes both specific genes, but also expansive genomic domains that invoke functions independent of a classical transcription factor. These findings support a new dual model for Myc chromatin function with important implications for the role of Myc in cancer and stem cell biology, including that of induced pluripotent stem (iPS) cells.