The Impact of the Long-Distance Transport of a BEL1-Like Messenger RNA on Development

BEL1- and KNOTTED1-type proteins are transcription factors from the three-amino-loop-extension superclass that interact in a tandem complex to regulate the expression of target genes. In potato (Solanum tuberosum), StBEL5 and its Knox protein partner regulate tuberization by targeting genes that control growth. RNA movement assays demonstrated that StBEL5 transcripts move through the phloem to stolon tips, the site of tuber induction. StBEL5 messenger RNA originates in the leaf, and its movement to stolons is induced by a short-day photoperiod. Here, we report the movement of StBEL5 RNA to roots correlated with increased growth, changes in morphology, and accumulation of GA2-oxidase1, YUCCA1a, and ISOPENTENYL TRANSFERASE transcripts. Transcription of StBEL5 in leaves is induced by light but insensitive to photoperiod, whereas in stolon tips growing in the dark, promoter activity is enhanced by short days. The heterodimer of StBEL5 and POTH1, a KNOTTED1-type transcription factor, binds to a tandem TTGAC-TTGAC motif that is essential for regulating transcription. The discovery of an inverted tandem motif in the StBEL5 promoter with TTGAC motifs on opposite strands may explain the induction of StBEL5 promoter activity in stolon tips under short days. Using transgenic potato lines, deletion of one of the TTGAC motifs from the StBEL5 promoter results in the reduction of GUS activity in new tubers and roots. Gel-shift assays demonstrate BEL5/POTH1 binding specificity to the motifs present in the StBEL5 promoter and a double tandem motif present in the StGA2-oxidase1 promoter. These results suggest that, in addition to tuberization, the movement of StBEL5 messenger RNA regulates other aspects of vegetative development.Fil: Lin, Tian. University of Iowa; Estados UnidosFil: Sharma, Pooja. University of Iowa; Estados UnidosFil: Gonzalez, Daniel Hector. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Viola, Ivana Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Agrobiotecnología del Litoral. Universidad Nacional del Litoral. Instituto de Agrobiotecnología del Litoral; ArgentinaFil: Hannapel, David J.. University of Iowa; Estados Unido

Hybrid Open-Loop Closed-Loop Control of Coupled Human-Robot Balance During Assisted Stance Transition with Extra Robotic Legs

A new approach to the human-robot shared control of the Extra Robotic Legs (XRL) wearable augmentation system is presented. The XRL system consists of two extra legs that bear the entirety of its backpack payload, as well as some of the human operator's weight. The XRL System must support its own balance and assist the operator stably while allowing them to move in selected directions. In some directions of the task space the XRL must constrain the human motion with position feedback for balance, while in other directions the XRL must have no position feedback, so that the human can move freely. Here, we present Hybrid Open-Loop / Closed-Loop Control Architecture for mixing the two control modes in a systematic manner. The system is reduced to individual joint feedback control that is simple to implement and reliable against failure. The method is applied to the XRL system that assists a human in conducting a nuclear waste decommissioning task. A prototype XRL system has been developed and demonstrated with a simulated human performing the transition from standing to crawling and back again while coupled to the prototype XRL system

GraphX: Unifying Data-Parallel and Graph-Parallel Analytics

From social networks to language modeling, the growing scale and importance of graph data has driven the development of numerous new graph-parallel systems (e.g., Pregel, GraphLab). By restricting the computation that can be expressed and introducing new techniques to partition and distribute the graph, these systems can efficiently execute iterative graph algorithms orders of magnitude faster than more general data-parallel systems. However, the same restrictions that enable the performance gains also make it difficult to express many of the important stages in a typical graph-analytics pipeline: constructing the graph, modifying its structure, or expressing computation that spans multiple graphs. As a consequence, existing graph analytics pipelines compose graph-parallel and data-parallel systems using external storage systems, leading to extensive data movement and complicated programming model. To address these challenges we introduce GraphX, a distributed graph computation framework that unifies graph-parallel and data-parallel computation. GraphX provides a small, core set of graph-parallel operators expressive enough to implement the Pregel and PowerGraph abstractions, yet simple enough to be cast in relational algebra. GraphX uses a collection of query optimization techniques such as automatic join rewrites to efficiently implement these graph-parallel operators. We evaluate GraphX on real-world graphs and workloads and demonstrate that GraphX achieves comparable performance as specialized graph computation systems, while outperforming them in end-to-end graph pipelines. Moreover, GraphX achieves a balance between expressiveness, performance, and ease of use

The Excitation of N2_2H+^+ in Interstellar Molecular Clouds. I - Models

We present LVG and non-local radiative transfer calculations involving the rotational and hyperfine structure of the spectrum of N$_2$H$^+$ with collisional rate coefficients recently derived by us. The goal of this study is to check the validity of the assumptions made to treat the hyperfine structure and to study the physical mechanisms leading to the observed hyperfine anomalies. We find that the usual hypothesis of identical excitation temperatures for all hyperfine components of the $J$=1-0 transition is not correct within the range of densities existing in cold dense cores, i.e., a few 10$^4$ \textless n(H$_2$) \textless a few 10$^6$ cm$^{-3}$. This is due to different radiative trapping effects in the hyperfine components. Moreover, within this range of densities and considering the typical abundance of N$_2$H$^+$, the total opacity of rotational lines has to be derived taking into account the hyperfine structure. The error made when only considering the rotational energy structure can be as large as 100%. Using non-local models we find that, due to saturation, hyperfine anomalies appear as soon as the total opacity of the $J$=1-0 transition becomes larger than $\simeq$ 20. Radiative scattering in less dense regions enhance these anomalies, and particularly, induce a differential increase of the excitation temperatures of the hyperfine components. This process is more effective for the transitions with the highest opacities for which emerging intensities are also reduced by self-absorption effects. These effects are not as critical as in HCO$^+$ or HCN, but should be taken into account when interpreting the spatial extent of the N$_2$H$^+$ emission in dark clouds.Comment: 13 pages, 12 figure

Analyzing the Atmospheric Conditions that Caused Two Unexpected Tornado Events

On May 25, 2016 and July 7, 2016, two individual tornadic storms occurred near Chapman, Kansas and Eureka, Kansas. Neither of these tornadic storms was forecast to occur by the National Oceanic and Atmospheric Administration’s (NOAA) Storm Prediction Center (SPC). In this research project, data from several online sources were analyzed to identify the atmospheric conditions around the times and near the concerned areas where the tornadoes spawned. Identifying and understanding the causes of these tornadoes will help future meteorologists better predict possible tornadoes in the future. Data was obtained from meteorological maps of surface pressure, temperature, dew-point temperature, wind speed and direction at the surface and aloft, and atmospheric soundings from nearby weather balloon locations. Areas of low pressure, cold fronts, warm fronts, dry-lines were identified by the process of analyzing the meteorological maps. Other atmospheric conditions that lead to the organization of the thunderstorms related to the tornadoes were also analyzed; namely, instability, vertical wind shear, moisture, and causes for lifting of air. Afterwards the focus was to determine the severity of the thunderstorms and how the tornadoes formed; doing so allows for the tornadic environments to be analyzed. For the Chapman tornado, the interactions of a new storm that initiated on the western flank of the primary storm likely played a role in the intensity of the tornado at various points along its path. For the Eureka tornado, interactions with the surface warm front likely provided the storm with necessary boundary-layer vorticity to support the tornado

An optimized tuned mass damper/harvester device

Much work has been conducted on vibration absorbers, such as tuned mass dampers (TMD), where significant energy is extracted from a structure. Traditionally, this energy is dissipated through the devices as heat. In this paper, the concept of recovering some of this energy electrically and reuse it for structural control or health monitoring is investigated. The energy-dissipating damper of a TMD is replaced with an electromagnetic device in order to transform mechanical vibration into electrical energy. That gives the possibility of controlled damping force whilst generating useful electrical energy. Both analytical and experimental results from an adaptive and a semi-active tuned mass damper/harvester are presented. The obtained results suggest that sufficient energy might be harvested for the device to tune itself to optimise vibration suppression