Impact of Cluster Thinning and Basal Leaf Removal on Fruit Quality of Cabernet Franc (Vitis vinifera L.) Grapevines Grown in Cool Climate Conditions

Achieving desired fruit quality at harvest in cool climate conditions is a challenge, especially for red varieties, and the typical inability of fruit to reach technological maturity is a critical contributing factor requiring examination. To probe this issue, this research investigated the impact of two levels of crop thinning and of basal leaf removal at three phenological stages in the 2011 and 2012 growing seasons in Michigan. Experiments were conducted at the Southwest Michigan Research and Extension Center (SWMREC) in Benton Harbor. Using \u2018Cabernet franc\u2019 (Vitis vinifera L.) vines, yield components (yield per vine, pruning weight, and cluster and berry weight) and basic fruit composition traits [total soluble solids (TSS), pH, titratable acidity, anthocyanins, and phenolics) were studied to investigate the effect of cluster thinning and basal leaf removal on vine performance and fruit quality at harvest. Neither of the treatments significantly impacted TSS in either of the two seasons. Cluster thinning treatment successfully altered cropload ratio, indexed as Ravaz Index (RI), independently of the time of application. Basal leaf removal increased exposed berry temperature, cluster light exposure, and subsequent anthocyanin and phenolic content of the berry in both seasons, again independent of application date, whereas cluster thinning was effective only in 2012. Crop thinning coupled with basal leaf removal resulted in an increased efficiency in anthocyanin accumulation in relation to TSS accumulation, expressed as anthocyanin:sugar, in both years. This is significant because it offers potential for vineyard management practices aiming to improve fruit quality in cool climates where the onset of anthocyanin accumulation could be reduced and decoupled from sugar accumulation

Hyperspectral darkfield microscopy of single hollow gold nanoparticles for biomedical applications

Hyperspectral microscopy is a versatile method for simultaneous spatial and spectroscopic characterization of nonfluorescent samples. Here we present a hyperspectral darkfield imaging system for spectral imaging of single nanoparticles over an area of 150 × 150 µm2 and at illumination intensities compatible with live cell imaging. The capabilities of the system are demonstrated using correlated transmission electron microscopy and single-particle optical studies of colloidal hollow gold nanoparticles. The potential of the system for characterizing the interactions between nanoparticles and cells has also been demonstrated. In this case, the spectral information proves a useful improvement to standard darkfield imaging as it enables differentiation between light scattered from nanoparticles and light scattered from other sources in the cellular environment. The combination of low illumination power and fast integration times makes the system highly suitable for nanoparticle tracking and spectroscopy in live-cell experiments

Localized surface plasmon resonance effects on the magneto-optical activity of continuous Au/Co/Au trilayers

We study how the magneto-optical activity in polar configuration of continuous Au/Co/Au trilayers is affected by the excitation of localized plasmon resonances of an array of Au nanodiscs fabricated on top of them over a dielectric SiO2 spacer. We show that the effect of the nanodiscs array is twofold. First, it optimizes the absorption of light at specific photon energies corresponding to the localized surface plasmon excitation of the array, modifying the reflectivity of the system (we define this effect as the purely optical contribution). Second, upon localized plasmon resonance excitation, the electromagnetic field in the whole system is redistributed, and an enhanced magneto-optical activity occurs at those energies where the electromagnetic field in the magnetic layer is increased (this effect is identified as the purely magneto-optical contribution of the nanodiscs array).This research was carried out with the financial support of the Spanish Ministry of Science and Education (NAN2004-09195-C04 and MAT2005-05524-C02-01), Comunidad de Madrid (S-0505/MAT/0194 NANOMAGNET) and the European Commission through the NoE PHOREMOST (FP6/2003/IST/2-511616). M. U. G. thanks the Spanish Ministry of Education for funding through the “Ramón y Cajal” program.Peer reviewe

Motor intention in the posterior parietal cortex:experimental data analysis and functional modeling study

The complexity of processes occurring in the brain is an intriguing issue not just for scientists and medical doctors, but the humanity in general. The cortex ability to perceive and analyze an enormous amount of information in an instance of time, the parallelism and computational efficiency are among the questions that attract attention. Even a simple, everyday gesture, for example, reaching for a cup of coffee, evokes a flow of signals in the brain. It goes from the primary visual region, that locates the cup on the table, to the primary motor region that sends the precise coordinates to the hand, and the instruction what to do next. The sequence of signal transmission and transformation continues through several regions, sensory, associative and motor ones. In this study, we will focus on the posterior parietal cortex, the region involved in the transformation of visual inputs into the preliminary motor plans. The years of experimental work revealed mechanisms for integration of multimodal signals, coordinate transformations, information representation in multiple coordinate frames, and many other. Still, a single encompassing theory about movement generation in the parietal cortex does not exist, and is a matter of debate. This study contributes to the analysis of motor intention in the 7a parietal region. The motor intention, a high-level cognitive signal, is defined as the preliminary plan for making a movement. From the engineering point of view, encoding of motor parameters in the neural activity is extensively studied within the framework of brain-computer interfaces. The motivation behind these studies is the development of neural prosthesis for the paralyzed persons. The direct cortical prosthesis can significantly improve the lives of paralyzed people, who have lost every other contact with the outside world. Also, this framework opens the possibilities for monitoring the neural processes during the execution of natural movements, and studying the mechanisms behind it. In this work, a method for identification of motor intention from the standard recordings of neural activity, the spike trains, is developed. The data of interest was collected in a series of behavioral experiments involving reaching or saccadic eye movements. The presence and absence of motor intention was monitored in various phases of motion execution, and for different types of movements. All the recordings obtained simultaneously are combined in the same decoding session. Therefore, the analysis is done using the activity of small population of cells (typically 8 to 12 cells). We aim to study the motor intention in a general context which requires using activity of multiple cells. The population size is determined by the experimental procedure. Throughout this study we assume that the motor intention can be red from the spike rates, the assumption supported by the neurophysiological studies. Therefore, all the simultaneously collected spike trains are converted into vectors of spike rates. The results of this study show that motor intention can be decoded from the spike rates. A machine-learning based algorithm is developed to analyze the presence or absence of motor intention in the obtained spike rate vectors. This algorithm, based on standard support vector machines, can distinguish between the segments of recordings that encode motor intention, from those that do not encode it. The goal of the study was to examine the precision of motor intention identification, when the activity of a randomly selected set of cells is analyzed using on such algorithm. Additionally, several relevant parameters were tested. The algorithm precision during different phases of movement execution is tested. Also, the influence of the population size and of the procedure for spike rates computation is examined. The obtained results demonstrated that the motor intention can be extracted from the neural signals with the precision of around 70% for a randomly selected set of cells. For the best groups of cells, this precision was 82%. The motor intention identification was particularly precise during the intervals of preparation and realization of saccadic eye movements. This is in accordance with the known functions of the 7a region, where the majority of cells respond to the eye movements. The algorithm precision is determined by the considered population size. For the bigger population the precision increases. Still, this conclusion holds only on average, since adding one or a couple of randomly selected cells does not have to change the result. Randomly selected cells do not necessary carry the information of interest. The influence of each of the cells, present in one set, is tested in this context. The obtained results indicate redundant coding of motor intention in the parietal cortex. Many cells carry the same information, and some of them can be removed from the set without changing the algorithm precision. Still, removing all of them degrades the result. Finally, the influence of the window size, used to compute spike rates in some of the tests is studied. In general, the precision improves when using bigger windows, the result that is consistent with the literature. Introducing the window for computing spike rates enables automatic identification of motor intention, the method suitable for the brain-computer interface applications. Finally, the analysis of the experimental data is complemented with the study of an appropriately designed model. Modeling the biological processes, in order to reveal additional functionality and test some parameters not accessible through the data, is a widely accepted approach. Still, the development of a model, sufficiently simple for implementation on the standard hardware, sufficiently tractable in the simulations, yet informative enough to capture the main processes of interest, is not straightforward. Our motivation for accepting this approach was to test several parameters that imposed themselves as important in the data analysis step. Due to the nature of the problem itself, the test on an approximative model was the only feasible tactic. The influence of the population size and the window size was assessed in this study. This, additionally, demonstrated the algorithm precision scaling as a function of the number of cells

Disease management in apples using trunk injection delivery of plant protective compounds

The two most important pathogens of apple Erwinia amylovora (fire blight) and Venturia inaequalis (apple scab) require pesticide sprays for control. This leads to accumulating side effects such as disease resistance, contamination of environment, elevated fungicide residues in fruit, and increased health risks to consumers and workers. While sprays are effective for disease control, need for increasing the sustainability of apple production by reducing pesticide use in the environment incited our research on delivering pesticides via trunk injection. This method delivers the compound into the canopy via tree xylem and could increase the efficiency in disease control. To find out how, where and when injected compounds distribute in the apple tree, thus affecting the efficiency in pest control, we injected imidacloprid through 1, 2, 4, or 8 injection ports per tree. By quantifying leaf residues we demonstrated variable spatial distribution of imidacloprid in the canopy. Spatial uniformity of distribution increased with more injection ports and 4 ports provided uniform distribution. To demonstrate the efficiency of injected compounds in fire blight and apple scab control we injected apple trees with antibiotics, plant resistance inducers, and fungicides. Antibiotics, potassium phosphites (PJ) and acibenzolar-S-methyl (ASM) provided weak control of blossom and shoot blight while oxytetracycline was the most efficient. ASM and PJ significantly expressed PR-1, 2, and 8 protein genes showing resistance activation in apple leaves (SAR) which suppressed the pathogen. Four injections of PJ in spring controlled leaf apple scab for 2 seasons, similar to 2 seasons of standard sprays. To optimize injections for apple scab control we evaluated 1-2 and 4 cross-seasonal and 1-2 seasonal injections of PJ and fungicides. PJ provided better scab control than propiconazole, cyprodinil and difenoconazole and showed better or equal and more persistent scab control with fewer injections than sprays. Control varied among canopy organs due to different transpiration, with best scab control on shoots, fruit, and then spurs. Good scab control is provided by 2-3 spring injections. Residues of synthetic fungicides in fruit were always below the residue tolerances. Fall injection did not improve apple scab control. To get temporally uniform imidacloprid distribution in the crown, best results were achieved by injection dose delivery at 4 times, 14 days apart. Injection method comparison showed that drill-based injection of the liquid imidacloprid formulation provided the highest residue concentration in the canopy when compared to other injection methods. Comparison of 7 trunk injection devices showed that drill-based devices did not provide higher residue concentration of cyprodinil and difenoconazole in apple leaf canopy when compared to needle-insertion device Bite, while Wedgle was similar. All the injection devices allowed similar apple scab control with fungicides. When monitoring the rate of trunk injection port healing in apple trees, we found that port closure with callus lasted for 1-1.3 and >2 years depending on the port size and type. Port closure was faster on the ports with smaller diameters. Around all injection port types, bark cracking due to frost events was higher in vertical direction of the trunk. The visible port depth declined faster on port from 11/64" drill bit and on lenticular injection port from double-edge blade, versus the port from 3/8" drill bit. When the port from 3/8" drill bit was sealed with an Arborplug, visible and covered port depths significantly increased in time due to callus formation on the top and laterally, around the plug. Overall, trunk injection of injection formulated pesticides could be a viable option for disease control in apples with minimal impact of injection ports on the tree.Thesis (Ph. D.)--Michigan State University. Plant Pathology, 2014Includes bibliographical reference