Combined in silico/in vivo analysis of mechanisms providing for root apical meristem self-organization and maintenance.

Background and aimsThe root apical meristem (RAM) is the plant stem cell niche which provides for the formation and continuous development of the root. Auxin is the main regulator of RAM functioning, and auxin maxima coincide with the sites of RAM initiation and maintenance. Auxin gradients are formed due to local auxin biosynthesis and polar auxin transport. The PIN family of auxin transporters plays a critical role in polar auxin transport, and two mechanisms of auxin maximum formation in the RAM based on PIN-mediated auxin transport have been proposed to date: the reverse fountain and the reflected flow mechanisms.MethodsThe two mechanisms are combined here in in silico studies of auxin distribution in intact roots and roots cut into two pieces in the proximal meristem region. In parallel, corresponding experiments were performed in vivo using DR5::GFP Arabidopsis plants.Key resultsThe reverse fountain and the reflected flow mechanism naturally cooperate for RAM patterning and maintenance in intact root. Regeneration of the RAM in decapitated roots is provided by the reflected flow mechanism. In the excised root tips local auxin biosynthesis either alone or in cooperation with the reverse fountain enables RAM maintenance.ConclusionsThe efficiency of a dual-mechanism model in guiding biological experiments on RAM regeneration and maintenance is demonstrated. The model also allows estimation of the concentrations of auxin and PINs in root cells during development and under various treatments. The dual-mechanism model proposed here can be a powerful tool for the study of several different aspects of auxin function in root

A Kinematic Measurement of Ram Pressure in the Outer Disk of Regular Galaxies

While most ram pressure studies have focused on ram pressure stripping in galaxy clusters, we devise a novel approach based on a kinematic measurement of ram pressure perturbations in HI velocity fields for intergalactic material (IGM) densities and relative velocities that are one to two orders of magnitude lower than in galaxies showing ram pressure stripping. Our model evaluates ram pressure induced kinematic terms in gas disks with constant inclination as well as those with a warped geometry. Ram pressure perturbations are characterized by kinematic modes of even order, m=0 and m=2, corresponding to a ram wind perpendicular and parallel to the gas disk, respectively. Long-term consequences of ram pressure, such as warped disks as well as uncertainties in the disk geometry typically generate uneven modes (m=1 and m=3), that are clearly distinguishable from the kinematic ram pressure terms. We have applied our models to three nearby isolated galaxies, utilizing Markov Chain Monte Carlo fitting routines to determine ram pressure perturbations in the velocity fields of NGC 6946 and NGC 3621 of ~30km s$^{-1}$ (effective line-of-sight velocity change) at HI column densities below (4-10)$\times$10$^{20}$cm$^{-2}$ (at radial scales greater than ~15kpc). In contrast, NGC 628 is dominated by a strongly warped disk. Our model fits reveal the three-dimensional vector of the galaxies' movement with respect to the IGM rest-frame and provide constraints on the product of speed with IGM density, opening a new window for extragalactic velocity measurements and studies of the intergalactic medium.Comment: 34 pages, 28 figures, accepted for publication in MNRA

Towards Practical Oblivious RAM

We take an important step forward in making Oblivious RAM (O-RAM) practical. We propose an O-RAM construction achieving an amortized overhead of 20X-35X (for an O-RAM roughly 1 terabyte in size), about 63 times faster than the best existing scheme. On the theoretic front, we propose a fundamentally novel technique for constructing Oblivious RAMs: specifically, we partition a bigger O-RAM into smaller O-RAMs, and employ a background eviction technique to obliviously evict blocks from the client-side cache into a randomly assigned server-side partition. This novel technique is the key to achieving the gains in practical performance

Ram Essential

The underlying causes of food insecurity are complex and often intertwined with related issues that affect a student’s ability to meet even basic needs, such as housing, employment and health care, forcing them to choose between their well-being and their education. The latest Hunger in America report finds that about 10 percent of Feed America’s 46.5 million adult clients are college students. That equates to 2 million full-time college students. “Of those surveyed by the emergency food services network, roughly 30.5 percent of students reported that they were forced to choose between food and educational expenses at some point over the last year.”1 In response, colleges and universities, including VCU, have sprung into action, and the number of campus food pantries at higher educational institutions has risen from a handful in 2009 to more than 500 in 2017.2 But changing food insecurity to food security goes beyond providing just food. It involves a comprehensive approach to providing resources that address the causes and results of being food insecure. Ram Essentials is a holistic approach to addressing basic needs insecurity among VCU students by asking the question, What is essential for our students to be successful? The project focuses on raising the awareness of all existing VCU resources and disseminating them widely through a single user-friendly portal to enhance students’ experience, academic achievement and physical and mental well-being

The "Ram Effect": A "Non-Classical" Mechanism for Inducing LH Surges in Sheep

During spring sheep do not normally ovulate but exposure to a ram can induce ovulation. In some ewes an LH surge is induced immediately after exposure to a ram thus raising questions about the control of this precocious LH surge. Our first aim was to determine the plasma concentrations of oestradiol (E2) E2 in anoestrous ewes before and after the "ram effect" in ewes that had a "precocious" LH surge (starting within 6 hours), a "normal" surge (between 6 and 28h) and "late» surge (not detected by 56h). In another experiment we tested if a small increase in circulating E2 could induce an LH surge in anoestrus ewes. The concentration of E2 significantly was not different at the time of ram introduction among ewes with the three types of LH surge. "Precocious" LH surges were not preceded by a large increase in E2 unlike "normal" surges and small elevations of circulating E2 alone were unable to induce LH surges. These results show that the "precocious" LH surge was not the result of E2 positive feedback. Our second aim was to test if noradrenaline (NA) is involved in the LH response to the "ram effect". Using double labelling for Fos and tyrosine hydroxylase (TH) we showed that exposure of anoestrous ewes to a ram induced a higher density of cells positive for both in the A1 nucleus and the Locus Coeruleus complex compared to unstimulated controls. Finally, the administration by retrodialysis into the preoptic area, of NA increased the proportion of ewes with an LH response to ram odor whereas treatment with the α1 antagonist Prazosin decreased the LH pulse frequency and amplitude induced by a sexually active ram. Collectively these results suggest that in anoestrous ewes NA is involved in ram-induced LH secretion as observed in other induced ovulators

How are Journal Impact, Prestige and Article Influence Related? An Application to Neuroscience.

The paper analyses the leading journals in Neurosciences using quantifiable Research Assessment Measures (RAM), highlights the similarities and differences in alternative RAM, shows that several RAM capture similar performance characteristics of highly cited journals, and shows that some other RAM have low correlations with each other, and hence add significant informational value. Alternative RAM are discussed for the Thomson Reuters ISI Web of Science database (hereafter ISI). The RAM that are calculated annually or updated daily include the classic 2-year impact factor (2YIF), 5-year impact factor (5YIF), Immediacy (or zero-year impact factor (0YIF)), Eigenfactor score, Article Influence score, C3PO (Citation Performance Per Paper Online), h-index, Zinfluence, PI-BETA (Papers Ignored - By Even The Authors), 2-year and historical Self-citation Threshold Approval Ratings (STAR), Impact Factor Inflation (IFI), and Cited Article Influence (CAI). The RAM are analysed for 26 highly cited journals in the ISI category of Neurosciences. The paper finds that the Eigenfactor score and PI-BETA are not highly correlated with the other RAM scores, so that they convey additional information regarding journal rankings, that Article Influence is highly correlated with some existing RAM, so that it has little informative incremental value, and that CAI has additional informational value to that of Article Influence. Harmonic mean rankings of the 13 RAM criteria for the 26 highly cited journals are also presented. Emphasizing the 2-year impact factor of a journal to the exclusion of other informative RAM criteria is shown to lead to a distorted evaluation of journal performance and influence, especially given the informative value of several other RAM.Impact factor, Prestige, Immediacy, Eigenfactor, Article Influence, h-index, C3PO, Zinfluence, PI-BETA, STAR, IFI, Cited Article influence.

Apparatus for measuring electrical properties of materials

Resistance of sample is measured with aid of usual electrical test instruments applied to electrical contacts provided at ram and anvil assemblies. Temperature differential is established between ram and anvil for measurement of Seebeck coefficient. Voltage generated across sample is detected at electrical contacts