Climate-driven regime shifts in a mangrove-salt marsh ecotone over the past 250 years.

Climate change is driving the tropicalization of temperate ecosystems by shifting the range edges of numerous species poleward. Over the past few decades, mangroves have rapidly displaced salt marshes near multiple poleward mangrove range limits, including in northeast Florida. It is uncertain whether such mangrove expansions are due to anthropogenic climate change or natural climate variability. We combined historical accounts from books, personal journals, scientific articles, logbooks, photographs, and maps with climate data to show that the current ecotone between mangroves and salt marshes in northeast Florida has shifted between mangrove and salt marsh dominance at least 6 times between the late 1700s and 2017 due to decadal-scale fluctuations in the frequency and intensity of extreme cold events. Model projections of daily minimum temperature from 2000 through 2100 indicate an increase in annual minimum temperature by 0.5 °C/decade. Thus, although recent mangrove range expansion should indeed be placed into a broader historical context of an oscillating system, climate projections suggest that the recent trend may represent a more permanent regime shift due to the effects of climate change

Selective dorsal rhizotomy for treatment of spasticity after hemispherectomy in children: A case report

Performing a hemispherotomy or hemispherectomy is known to treat medically intractable epilepsy successfully, yet contralateral hemiparesis and increased muscle tone follow the epilepsy surgery. Spasticity and coexisting dystonia presumably cause the increased muscle tone in the lower extremity on the opposite side of epilepsy surgery. However, the extent of the role of spasticity and dystonia in high muscle tone is unknown. A selective dorsal rhizotomy is performed to reduce spasticity. If a selective dorsal rhizotomy is performed in the affected patient and muscle tone is reduced, the high muscle tone is not due to dystonia. Two children, who previously underwent a hemispherectomy or hemispherotomy, had a selective dorsal rhizotomy (SDR) performed in our clinic. Both children underwent orthopedic surgery to treat heel cord contractures. To study the extent of the role of spasticity and dystonia in high muscle tone, the mobility of the two children was examined pre- and post-SDR. The children had follow-ups 12 months and 56 months after SDR to study long-term effects. Before SDR, both children showed signs of spasticity. The SDR procedure removed spasticity, and muscle tone in the lower extremity became normal. Importantly, dystonia did not surface after SDR. Patients started independent walking less than two weeks after SDR. Sitting, standing, walking, and balance improved. They could walk longer distances while experiencing less fatigue. Running, jumping, and other more vigorous physical activities became possible. Notably, one child showed voluntary foot dorsiflexion that was absent before SDR. The other child showed improvement in voluntary foot dorsiflexion that was present before SDR. Both children maintained the progress at the 12 and 56-month follow-up visits. The SDR procedure normalized muscle tone and improved ambulation by removing spasticity. The high muscle tone following the epilepsy surgery was not due to dystonia

Expanded genetic screening in Caenorhabditis elegans identifies new regulators and an inhibitory role for NAD+ in axon regeneration.

The mechanisms underlying axon regeneration in mature neurons are relevant to the understanding of normal nervous system maintenance and for developing therapeutic strategies for injury. Here, we report novel pathways in axon regeneration, identified by extending our previous function-based screen using the C. elegans mechanosensory neuron axotomy model. We identify an unexpected role of the nicotinamide adenine dinucleotide (NAD+) synthesizing enzyme, NMAT-2/NMNAT, in axon regeneration. NMAT-2 inhibits axon regrowth via cell-autonomous and non-autonomous mechanisms. NMAT-2 enzymatic activity is required to repress regrowth. Further, we find differential requirements for proteins in membrane contact site, components and regulators of the extracellular matrix, membrane trafficking, microtubule and actin cytoskeleton, the conserved Kelch-domain protein IVNS-1, and the orphan transporter MFSD-6 in axon regrowth. Identification of these new pathways expands our understanding of the molecular basis of axonal injury response and regeneration

AN ONBOARD HYDROGEN GENERATION METHOD BASED ON HYDRIDES AND WATER RECOVERY FOR MICRO-FUEL CELLS

poster abstractThe purpose of this paper is to conduct experiments to generate hydrogen in a fuel cell by employing hydrides and water recovery methods. Micro-proton exchange membrane fuel cells are the next generation power source for micro-scale applications. The methods presented in the paper make use of the recycled water produced from the cathode reaction to develop high energy density micro fuel cells. The method for this experiment is accomplished by utilizing oxidation-reduction reactions that take place in the cell. These reactants must be constantly replenished through an external source. This paper will introduce the methods and procedures that permit a solution to the small-scale generation of fuel and water byproduct; this is accomplished by implementing a water recovery mechanism. The experiment commenced with designing and manufacturing a Nafion membrane and a fuel cell package. From then the calcium hydride and lithium aluminum hydride was loaded. These hydrides were given controlled amounts of water vapor and the amount of gas production was measured. After the amount of gas is measured, we are able to calculate the most efficient way to receive the greatest amount of hydrogen from the cell. The objective of our experiment is to achieve a higher energy density for micro-fuel cells. Our aim is that the results of our research will replace lithium ion batteries with a high energy density fuel cell that can increase longevity as a source, and is able to be used in multiple environments including pace makers and space exploration. Multidisciplinary Undergraduate Research Institute, CRL Program

A Multi-Code Analysis Toolkit for Astrophysical Simulation Data

The analysis of complex multiphysics astrophysical simulations presents a unique and rapidly growing set of challenges: reproducibility, parallelization, and vast increases in data size and complexity chief among them. In order to meet these challenges, and in order to open up new avenues for collaboration between users of multiple simulation platforms, we present yt (available at http://yt.enzotools.org/), an open source, community-developed astrophysical analysis and visualization toolkit. Analysis and visualization with yt are oriented around physically relevant quantities rather than quantities native to astrophysical simulation codes. While originally designed for handling Enzo's structure adaptive mesh refinement (AMR) data, yt has been extended to work with several different simulation methods and simulation codes including Orion, RAMSES, and FLASH. We report on its methods for reading, handling, and visualizing data, including projections, multivariate volume rendering, multi-dimensional histograms, halo finding, light cone generation and topologically-connected isocontour identification. Furthermore, we discuss the underlying algorithms yt uses for processing and visualizing data, and its mechanisms for parallelization of analysis tasks.Comment: 18 pages, 6 figures, emulateapj format. Resubmitted to Astrophysical Journal Supplement Series with revisions from referee. yt can be found at http://yt.enzotools.org

Cellular electroporation induces dedifferentiation in intact newt limbs

AbstractNewts have the remarkable ability to regenerate lost appendages including their forelimbs, hindlimbs, and tails. Following amputation of an appendage, the wound is rapidly closed by the migration of epithelial cells from the proximal epidermis. Internal cells just proximal to the amputation plane begin to dedifferentiate to form a pool of proliferating progenitor cells known as the regeneration blastema. We show that dedifferentiation of internal appendage cells can be initiated in the absence of amputation by applying an electric field sufficient to induce cellular electroporation, but not necrosis or apoptosis. The time course for dedifferentiation following electroporation is similar to that observed following amputation with evidence of dedifferentiation beginning at about 5 days postelectroporation and continuing for 2 to 3 weeks. Microarray analyses, real-time RT-PCR, and in situ hybridization show that changes in early gene expression are similar following amputation or electroporation. We conclude that the application of an electric field sufficient to induce transient electroporation of cell membranes induces a dedifferentiation response that is virtually indistinguishable from the response that occurs following amputation of newt appendages. This discovery allows dedifferentiation to be studied in the absence of wound healing and may aid in identifying genes required for cellular plasticity