Comparison of production systems for potato (Solanum tuberosum L.) minituber production with different cultivars : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Applied Science in Nursery Production

The purpose of these studies is to determine the effect of different production systems (Aeroponic (AP), Deep flow (DF), Nutrition film technique (NFT) and Bark) on production of first generation (prebasic) potato (Solanum tuberosum L.) minitubers with different cultivars (Russet Burbank, Rua, Kenebec, Atlantic and Diésrée). Prebasic tubers usually multiplied in a greenhouse in a bark medium. Replacing the bark based system by a highly intensive aeroponic system is viable. The aeroponic system significantly produced higher tuber numbers per plant and produced a higher percentage (82%) of 1 -2g size tuber than other systems evaluated. In aeroponic and deep flow systems, the time to tuberization is higher. When tuberization is delayed, stolons grow continuously in the deep flow and aeroponic systems. In hydroponic systems a developing stolons did not encounter sufficient mechanical resistance to limit growth, they grew extremely vigorously and very wide of diameter (1.92- 2.42 mm). When roots and stolons filled the aeroponic and deep flow containers some root rustication occurred then tubers were initiated. Acid treatment efficiently synchronised tuberization in the aeroponic systems, tubers were visible four days after acid treatment. Optimum acid treatment depends on the specific cultivar or stage of stolon development. Rua produced the highest yield per plant and highest tuber number per plant. The pH and treatment time significantly affected the tuber number per plant. Acid treatment at pH 3.5 produced the highest tuber number (19.8) per plant. Minitubers show a dormant period immediately after they are harvested. Application of GA is a useful method to break minituber dormancy. Fifty percentage of the GA treated tubers sprouted within 20 days after treatment, while untreated control took 37 days. Overall, sprouting was highest for 100 ppm treatment, but was not significantly different from 30 ppm. The highest and lowest sprouting cultivars were Russet Burbank and Atlantic respectively. Potato cuttings can be propagated in an aeroponic system. Application of IBA treatment at 0.1 to 0.3% significantly induced root formation and root growth. About 80% of the IBA treated cuttings rooted and produced longer roots than untreated cuttings. From these studies we found the aeroponic system to be suitable for minituber production as well as the propagation of potato cuttings. Production of high tuber number per plant in aeroponic systems will reduced the production cost and reduce the number of field multiplications required before final cropping

Explicit congestion control algorithms for available bit rate services in asynchronous transfer mode networks

Congestion control of available bit rate (ABR) services in asynchronous transfer mode (ATM) networks has been the recent focus of the ATM Forum. The focus of this dissertation is to study the impact of queueing disciplines on ABR service congestion control, and to develop an explicit rate control algorithm. Two queueing disciplines, namely, First-In-First-Out (FIFO) and per-VC (virtual connection) queueing, are examined. Performance in terms of fairness, throughput, cell loss rate, buffer size and network utilization are benchmarked via extensive simulations. Implementation complexity analysis and trade-offs associated with each queueing implementation are addressed. Contrary to the common belief, our investigation demonstrates that per-VC queueing, which is costlier and more complex, does not necessarily provide any significant improvement over simple FIFO queueing. A new ATM switch algorithm is proposed to complement the ABR congestion control standard. The algorithm is designed to work with the rate-based congestion control framework recently recommended by the ATM Forum for ABR services. The algorithm\u27s primary merits are fast convergence, high throughput, high link utilization, and small buffer requirements. Mathematical analysis is done to show that the algorithm converges to the max-min fair allocation rates in finite time, and the convergence time is proportional to the distinct number of fair allocations and the round-trip delays in the network. At the steady state, the algorithm operates without causing any oscillations in rates. The algorithm does not require any parameter tuning, and proves to be very robust in a large ATM network. The impact of ATM switching and ATM layer congestion control on the performance of TCP/IP traffic is studied and the results are presented. The study shows that ATM layer congestion control improves the performance of TCP/IP traffic over ATM, and implementing the proposed switch algorithm drastically reduces the required switch buffer requirements. In order to validate claims, many benchmark ATM networks are simulated, and the performance of the switch is evaluated in terms of fairness, link utilization, response time, and buffer size requirements. In terms of performance and complexity, the algorithm proposed here offers many advantages over other proposed algorithms in the literature

Downregulation of selective microRNAs in trigeminal ganglion neurons following inflammatory muscle pain

Active regulation of gene expression in the nervous system plays an important role in the development and/or maintenance of inflammatory pain. MicroRNA (miRNA) negatively regulates gene expression via posttranscriptional or transcriptional inhibition of specific genes. To explore the possible involvement of miRNA in gene regulation during inflammatory pain, we injected complete Freund's adjuvant (CFA) unilaterally into the rat masseter muscle and quantified changes in neuron-specific mature miRNAs in the trigeminal ganglion (TG). Real-time reverse-transcription polymerase chain reaction revealed significant, but differential, downregulation of mature miR-10a, -29a, -98, -99a, -124a, -134, and -183 in the ipsilateral mandibular division (V3) of the TG within 4 hr after CFA. In contrast, levels of tested miRNAs did not change significantly in the contralateral V3 or the ipsilateral ophthalmic and maxillary divisions of the TG from inflamed rats, nor in the ipsilateral V3 of saline-injected animals. The downregulated miRNAs recovered differentially to a level equal to or higher than that in naive animals. Full recovery time varied with miRNA species but was at least 4 days. Expression and downregulation of some miRNAs were further confirmed by in situ hybridization of TG neurons that innervate the inflamed muscle. Although neurons of all sizes expressed these miRNAs, their signals varied between neurons. Our results indicate that miRNA species specific to neurons are quickly regulated following inflammatory muscle pain

Agronomic and economic viability of Miscanthus x giganteus as a novel biofuel in the Maryland climate

Gemstone Team BiofuelsOur study examined the effects of land quality and water-absorbent polymer on the growth of Miscanthus x giganteus. Our goal was to help utilize previously uncultivable land efficiently and meet U.S. energy goals. Currently, most U.S. biofuel is produced from corn, which requires arable land for growth and therefore significantly disrupts the production of food crops. We predicted that M. x giganteus would be able to thrive on marginal land, unlike corn, with the aid of a water-absorbing polymer. After growing M. x giganteus on both arable and marginal land, with and without the application of a polymer, we found that our crop grew better on the arable land. We also found that the presence of the water-absorbing polymer in the soil did not affect the growth of M. x giganteus. Finally, an economic cost-benefit analysis showed that growing M. x giganteus would not be a viable commercial enterprise, without the use of a commercial fertilizer and based on existing revenue and expense scenarios

Sensorimotor integration and motor learning during a novel force-matching task in young adults with attention-deficit/hyperactivity disorder

IntroductionAttention-Deficit/Hyperactivity Disorder (ADHD) is a neurodevelopmental disorder that exhibits unique neurological and behavioral characteristics. Those with ADHD often have noted impairments in motor performance and coordination, including during tasks that require force modulation. The present study provides insight into the role of altered neural processing and SMI in response to a motor learning paradigm requiring force modulation and proprioception, that previous literature has suggested to be altered in those with ADHD, which can also inform our understanding of the neurophysiology underlying sensorimotor integration (SMI) in the general population.MethodsAdults with ADHD (n = 15) and neurotypical controls (n = 15) performed a novel force-matching task, where participants used their right-thumb to match a trace template that varied from 2–12% of their Abductor Pollicis Brevis maximum voluntary contraction. This motor task was completed in pre, acquisition, and post blocks. Participants also completed a retention test 24 h later. Median nerve somatosensory-evoked potentials (SEPs) were collected pre and post motor acquisition. SEPs were stimulated at two frequencies, 2.47 Hz and 4.98 Hz, and 1,000 sweeps were recorded using 64-electrode electroencephalography (EEG) at 2,048 Hz. SEP amplitude changes were normalized to each participant’s baseline values for that peak.ResultsBoth groups improved at post measures (ADHD: 0.85 ± 0.09; Controls: 0.85 ± 0.10), with improvements maintained at retention (ADHD: 0.82 ± 0.11; Controls: 0.82 ± 0.11). The ADHD group had a decreased N18 post-acquisition (0.87 ± 0.48), while the control N18 increased (1.91 ± 1.43). The N30 increased in both groups, with a small increase in the ADHD group (1.03 ± 0.21) and a more pronounced increase in controls (1.15 ± 0.27).DiscussionUnique neural differences between groups were found after the acquisition of a novel force-matching motor paradigm, particularly relating to the N18 peak. The N18 differences suggest that those with ADHD have reduced olivary-cerebellar-M1 inhibition when learning a novel motor task dependent on force-modulation, potentially due to difficulties integrating the afferent feedback necessary to perform the task. The results of this work provide evidence that young adults with ADHD have altered proprioceptive processing when learning a novel motor task when compared to neurotypical controls

Imprinting.

Imprinting is a type of learning by which an animal restricts its social preferences to an object after exposure to that object. Filial imprinting occurs shortly after birth or hatching and sexual imprinting, around the onset of sexual maturity; both have sensitive periods. This review is concerned mainly with filial imprinting. Filial imprinting in the domestic chick is an effective experimental system for investigating mechanisms underlying learning and memory. Extensive evidence implicates a restricted part of the chick forebrain, the intermediate and medial mesopallium (IMM), as a memory store for visual imprinting. After imprinting to a visual stimulus, neuronal responsiveness in IMM is specifically biased toward the imprinting stimulus. Both this bias and the strength of imprinting measured behaviorally depend on uninterrupted sleep shortly after training. When learning-related changes in IMM are lateralized they occur predominantly or completely on the left side. Ablation experiments indicate that the left IMM is responsible for long-term storage of information about the imprinting stimulus; the right side is also a store but additionally is necessary for extra storage outside IMM, in a region necessary for flexible use of information acquired through imprinting. Auditory imprinting gives rise to biochemical, neuroanatomical, and electrophysiological changes in the medio-rostral nidopallium/mesopallium, anterior to IMM. Auditory imprinting has not been shown to produce learning-related changes in IMM. Imprinting may be facilitated by predispositions. Similar predispositions for faces and biological motion occur in domestic chicks and human infants. WIREs Cogn Sci 2013, 4:375-390. doi: 10.1002/wcs.1231 For further resources related to this article, please visit the WIREs website.This review is written in memory of the late Sir Gabriel Horn, in recognition of his pioneering work on the neurobiology of imprinting. I am indebted to Robert Levin, Alister Nicol, Revaz Solomonia, Rie Suge, and two anonymous referees for valuable comments on a draft manuscript. The review was written while in receipt of a project grant from the Biotechnology and Biological Sciences Research Council.This is the author accepted manuscript. The final version is available from Wiley via http://dx.doi.org/10.1002/wcs.123

In pursuit of P2X3 antagonists: novel therapeutics for chronic pain and afferent sensitization

Treating pain by inhibiting ATP activation of P2X3-containing receptors heralds an exciting new approach to pain management, and Afferent's program marks the vanguard in a new class of drugs poised to explore this approach to meet the significant unmet needs in pain management. P2X3 receptor subunits are expressed predominately and selectively in so-called C- and Aδ-fiber primary afferent neurons in most tissues and organ systems, including skin, joints, and hollow organs, suggesting a high degree of specificity to the pain sensing system in the human body. P2X3 antagonists block the activation of these fibers by ATP and stand to offer an alternative approach to the management of pain and discomfort. In addition, P2X3 is expressed pre-synaptically at central terminals of C-fiber afferent neurons, where ATP further sensitizes transmission of painful signals. As a result of the selectivity of the expression of P2X3, there is a lower likelihood of adverse effects in the brain, gastrointestinal, or cardiovascular tissues, effects which remain limiting factors for many existing pain therapeutics. In the periphery, ATP (the factor that triggers P2X3 receptor activation) can be released from various cells as a result of tissue inflammation, injury or stress, as well as visceral organ distension, and stimulate these local nociceptors. The P2X3 receptor rationale has aroused a formidable level of investigation producing many reports that clarify the potential role of ATP as a pain mediator, in chronic sensitized states in particular, and has piqued the interest of pharmaceutical companies. P2X receptor-mediated afferent activation has been implicated in inflammatory, visceral, and neuropathic pain states, as well as in airways hyperreactivity, migraine, itch, and cancer pain. It is well appreciated that oftentimes new mechanisms translate poorly from models into clinical efficacy and effectiveness; however, the breadth of activity seen from P2X3 inhibition in models offers a realistic chance that this novel mechanism to inhibit afferent nerve sensitization may find its place in the sun and bring some merciful relief to the torment of persistent discomfort and pain. The development philosophy at Afferent is to conduct proof of concept patient studies and best identify target patient groups that may benefit from this new intervention