New Results on Stability Analysis of Uncertain Neutral-Type Lur'e Systems Derived from a Modified Lyapunov-Krasovskii Functional

This paper is concerned with the problem of the absolute and robustly absolute stability for the uncertain neutral-type Lur’e system with time-varying delays. By introducing a modified Lyapunov-Krasovskii functional (LKF) related to a delay-product-type function and two delay-dependent matrices, some new delay-dependent robustly absolute stability criteria are proposed, which can be expressed as convex linear matrix inequality (LMI) framework. The criteria proposed in this paper are less conservative than some recent previous ones. Finally, some numerical examples are presented to show the effectiveness of the proposed approach

New Results on Delay-Dependent Stability Analysis and Stabilization of Time-Delay Systems

The interconnection between physical systems is accomplished by flow of information, energy and material, alternatively known as transport or propagation. As such flows may take a finite amount of time, the reaction of real world systems to exogenous or feedback control signals, from automatic control perspective, are not instantaneous. This results time-delays in systems connected by real-world physical media. Indeed, examples of time-delay systems span biology, ecology, economy, and of course, engineering. To this end, it is known that an arbitrary small delay may destabilize a stable system whereas, a delay in the controller may be used to stabilize a system that is otherwise not stabilizable by using a delay-free controller. In general, the presence of time-delay in a system makes the system dynamics infinite-dimensional, and analysis of such systems is complex.This thesis investigates stability analysis and stabilization of time-delay systems. It proposes a delay-decomposition approach for stability analysis of systems with single delay that leads to a simple LMI condition using a Lyapunov-Krasovskii functional. Moreover, a static state feedback controller is designed for systems with state and input-delay using this delay-decomposition approach. Numerical comparison of the present results vis-`a-vis the existing ones for the systems with constant delay considered shows that the present ones are superior. Next, a PI-type controller is implemented for systems with input-delay to improve the tolerable delay bound. Other problems considered is to analyze the stability of systems with two delays. As the number of delays incorporated in the system dynamics increases, it becomes further complex for analysis

Novel MRI Technologies for Structural and Functional Imaging of Tissues with Ultra-short T₂ Values

Conventional MRI has several limitations such as long scan durations, motion artifacts, very loud acoustic noise, signal loss due to short relaxation times, and RF induced heating of electrically conducting objects. The goals of this work are to evaluate and improve the state-of-the-art methods for MRI of tissue with short T₂, to prove the feasibility of in vivo Concurrent Excitation and Acquisition, and to introduce simultaneous electroglottography measurement during functional lung MRI

Epidemiological cellular automata: a case study involving AIDS

The spread of disease is a major health concern in many parts of the world. In the absence of vaccines and treatments, the only method to stop the spread of disease is to control population movements. Human mobility is one of the causes of the geographical spread of emergent human infectious diseases and plays a key role in human-mediated bio-invasion, the dominant factor in the global biodiversity crisis. One of the most serious emergent infectious diseases in the last 30 years or so is AIDS (acquired immunodeficiency syndrome), where multiple pathogen species infect a human body. HIV/AIDS is now considered much more commonplace than previously thought. AIDS leads to interaction effects between the pathogens that may alter previously understood patterns of disease spread. There has been longstanding interest in how to model population movements in order to find optimal control strategies for a particular disease. The simulation models proposed here use cellular automata based on sound mathematical principles and epidemiological theory to model HIV/AIDS to provide a suitable framework to study the spatial spread of disease in different scenarios. This work investigates how probabilistic parameters affect the model in terms of time, location, gender, age and subgroups of the population. The cellular automaton modelling approach is used to forecast numbers of cases in different subgroups. An approach using wavelet transforms analysis is illustrated to understand the impact of delay on the spread of infectious disease. The results confirm that the higher the frequency, then the slower the spread of disease and vice versa. The thesis concludes with showing how co-infection can be modelled in future work on a theoretical base

Abiotic stress hormesis in carrots : disease resistance, physiological stress responses and enhancement of volatile phytochemicals

L'entreposage à long terme des carottes (Daucus carota L.) est principalement limité par les maladies fongiques et les pourritures post-récolte. L'utilisation du potentiel physiologique des carottes pourrait être une alternative intéressante aux applications de fongicide pour lutter contre ces maladies. Les stress abiotiques sont de nature oxydative et s'avèrent souvent nocifs aux plantes et aux tissus végétaux à fortes doses, mais peuvent induire des mécanismes protecteurs / adaptatifs à faibles doses, un phénomène biologique appelé hormèse. Cependant, exception faite des rayons UV-C, on sait peu de choses quant aux possibles effets hormétiques des stress abiotiques sur les produits post-récolte tel que les carottes. Ainsi l'objectif général de ce travail était d'établir l'existence de l'hormèse chez les racines de carotte suite à l'exposition à divers stress abiotiques, incluant les radiations UV, la lumière blanche, la chaleur, les ultrasons, l'ozone et l'éthylène et d'étudier l'effet des doses hormétiques de ces stress sur la résistance aux maladies. Plus précisément, la démarche consistait à déterminer les doses hormétiques des stress dans l'intensification de la résistance aux maladies chez les carottes conservées à 4 °C, suivre les changements physiologiques et biochimiques des carottes exposées aux stress, et évaluer l'induction ou l'accroissement des teneurs de différents phyto-composés aux propriétés antimicrobiennes et/ou bénéfiques pour la santé (connues ou potentielles) chez les carottes exposées, et leur évolution au cours d'un entreposage de 42 jours à 4 °C. Tous les stress abiotiques sélectionnés présentaient le phénomène d'hormèse chez les carottes entreposées à 4 °C (> 95% humidité relative) avec une résistance accrue, à divers degrés, à la maladie causée par Botrytis cinerea. Les doses hormétiques des stress étaient: 7,0 kJ∙m⁻² (UV-B); 30 kJ∙m⁻² (lumière blanche); 60 min (chaleur, 36 °C); 30 min (ultrasons, 135 W); 6,0 h (ozone, 5,0 ppm) et 6,5 h (éthylène, 250 ppm). Appliqués aux doses hormétiques, les ultrasons avec H₂O₂, les UV-B, l'ozone, la lumière blanche et l'éthylène étaient les stress les plus efficaces (60 à 65% réduction de la maladie). La deuxième partie de cette étude consistait à suivre au cours de l'entreposage les changements physiologiques (taux de respiration, fuite d'électrolytes et perte de poids) et biochimiques (capacité antioxydante) des carottes, suite à l'exposition aux stress susmentionnés. Les ultrasons avec H₂O₂ et l'ozone, ont davantage, bien que transitoirement, provoqué des changements dans les caractéristiques physiologiques et biochimiques des carottes exposées. De plus, les D₅₀ (doses efficaces à 50%), déterminées à partir des courbes de réponse physiologique, sont comparables aux doses hormétiques obtenue en utilisant la réponse de résistance à la maladie. Dans la troisième partie du travail, l'effet des stress (appliqués aux doses hormétiques) sur les carottes entreposées a été évalué sur l'induction / l'augmentation des niveaux de quatre phyto-composés, antimicrobiens connus ou potentiels, et sur leur contribution à la résistance induite aux maladies. La lumière blanche a été la plus efficace dans l'induction de la phytoalexine 6-méthoxymelléine, suivie des UV-C, des ultrasons avec H₂O₂, de l'ozone et des UV-B; la lumière blanche et les UV-C dans l'augmentation des polyacétylènes antifongiques constitutifs, le falcarinol et le falcarindiol. La lumière blanche et l'éthylène ont augmenté les niveaux de myristicine. Dans l'ensemble, la lumière blanche et les UV, suivis des ultrasons avec H₂O₂ et de l'éthylène, ont été les plus efficaces pour augmenter les niveaux de ces composés. La 6-méthoxymélléine s'est révélée comme le principal phyto-composé impliqué dans la résistance induite par les stress abiotiques, tandis que les polyacétylènes, le falcarinol et le falcarindiol dans une moindre mesure, joueraient un rôle d'adjuvant. La myristicine ne semble jouer aucun rôle dans la résistance induite aux maladies chez les carottes. Enfin, l'examen des profils des phyto-composés relativement volatils bénéfiques pour la santé (phénylpropanoïdes, terpénoïdes, polycétides et polyacétylènes) obtenus par GC-MS montre une augmentation à des degrés divers de tous les composés en réponse aux différents stress hormétiques. Dans l'ensemble, la lumière blanche, les ultrasons avec H₂O₂, l'ozone et les UV-C se sont montrés efficaces pour augmenter les niveaux des diverses classes de composés précités. Considérant l'amélioration de la résistance aux maladies; l'augmentation des niveaux des phyto-composés, en particulier de la phytoalexine 6-méthoxymélléine; protecteurs des plantes et/ou bénéfiques pour la santé, la lumière blanche, les ultrasons avec H₂O₂, ou l'ozone pourraient être des stress hormétiques souhaitables pour le traitement des carottes entreposées.Long-term storage of carrots (Daucus carota L.) is limited mainly by fungal diseases and decay. Utilizing the physiological potential of the produce to elevate disease resistance could be an attractive alternative to fungicide applications to control diseases in stored carrots. Abiotic stresses are oxidative in nature and often prove harmful to plants at high doses, but may induce protective/adaptive mechanisms at low doses, a biological phenomenon known as hormesis. However, little is known regarding the existence of hormesis of other abiotic stresses, other than UV-C radiation, in postharvest crops, including carrots, nor their hormetic effects in carrots, if any. The overall objective of this work was to establish the existence of hormesis phenomenon of various abiotic stresses, including UV radiations and white light (WL), heat, ultrasound (US), ozone (O₃), and ethylene (ET) in carrot roots, and investigate the potential of pre-storage treatment with hormetic doses of those stresses to enhance the disease resistance of stored carrots. Specifically, the approach consisted of determining the hormetic doses of stresses in the intensification of disease resistance in carrots stored at 4 °C; monitoring the physiological and biochemical changes in the stress-exposed carrots; and evaluating the induction or enhancement of phyto-compounds with antimicrobial and/or health-beneficial properties of the exposed carrots, and their dynamics during storage of 42 days. All the selected abiotic stresses exhibited the phenomenon of hormesis in carrots stored at 4 °C (> 95% relative humidity) with enhanced disease resistance against decay caused by Botrytis cinerea to varying degrees. The hormetic doses of the selected abiotic stresses for the induction of disease resistance in carrots were: 7.0 kJ∙m⁻² (UV-B), 30 kJ∙m⁻² (WL); 60 min (heat at 36 °C), and 30 min (US at 135 W); 6.0 h (O₃ at 5 ppm); and 6.5 h (ET at 250 ppm). Hormetic doses of US+H₂O₂, UV-B, O₃, WL, and ET were the most effective among the stresses to induce resistance (60-65% disease reduction). The second part of this research work was to evaluate changes in the physiological(respiration rate, electrolyte leakage, and weight loss) and biochemical (antioxidant capacity) characteristics of the carrots, following exposure to the afore-mentioned stresses during 6 weeks of storage. Among the stresses, US+H₂O₂ and O₃, most markedly, albeit transiently, caused changes in the physiological and biochemical characteristics of the exposed carrots. Furthermore, the D₅₀ (effective dose at 50%) doses, determined from the sigmoidal stress dose-changes in the physiological and biochemical response curves appeared to represent the hormetic doses comparable to those obtained using the disease resistance response. The third part of the work evaluated the hormetic doses of abiotic stresses for their capacity to induce/enhance the levels of four targeted phyto-compounds, either known or potential antimicrobials, and their contribution to the disease resistance against B. cinerea. Hormetic WL was most effective in the induction of the isocoumarin phytoalexin, 6-methoxymellein (6-MM), followed by UV-C, US+H₂O₂, O₃, and UV-B stresses; WL and UV-C in the enhancement of the constitutive antifungal polyacetylenes, falcarinol (FaOH) and falcarindiol (FaDOH); and WL and ET were effective in enhancing the insecticidal phenylpropene, myristicin (MYR). Overall, WL, UV radiations, followed by US+H₂O₂ and ET, were most effective in the enhancement of those four compounds. The phytoalexin, 6-MM, was the principal phyto-compound involved in the resistance, while FaOH and FaDOH played an adjuvant role, and MYR did not seem to play any role. The final portion of this work examined the profiles of relatively volatile health-beneficial phyto-compounds in carrots using GC-MS and their enhancement in response to hormetic abiotic stresses. All the phyto-compounds (phenylpropanoids, terpenoids, polyketides, and polyacetylenes) were enhanced to varying degrees by different hormetic stresses. Overall, the effective stresses for the enhancement of diverse classes of volatile health-beneficial phyto-compounds were WL, US+H₂O₂, O₃, and UV-C. From the standpoints of improved disease resistance; the enhancement of antimicrobial targeted phyto-compounds, specifically the phytoalexin, 6-MM; and that of volatile compounds that are both plant-protecting and health-beneficial, application of hormetic stresses, WL, US+H₂O₂, or O₃, could be desirable in practice, for not only controlling diseases in carrots, but also improving their health-beneficial properties

Vibrotactile Sensory Augmentation and Machine Learning Based Approaches for Balance Rehabilitation

Vestibular disorders and aging can negatively impact balance performance. Currently, the most effective approach for improving balance is exercise-based balance rehabilitation. Despite its effectiveness, balance rehabilitation does not always result in a full recovery of balance function. In this dissertation, vibrotactile sensory augmentation (SA) and machine learning (ML) were studied as approaches for further improving balance rehabilitation outcomes. Vibrotactile SA provides a form of haptic cues to complement and/or replace sensory information from the somatosensory, visual and vestibular sensory systems. Previous studies have shown that people can reduce their body sway when vibrotactile SA is provided; however, limited controlled studies have investigated the retention of balance improvements after training with SA has ceased. The primary aim of this research was to examine the effects of supervised balance rehabilitation with vibrotactile SA. Two studies were conducted among people with unilateral vestibular disorders and healthy older adults to explore the use of vibrotactile SA for therapeutic and preventative purposes, respectively. The study among people with unilateral vestibular disorders provided six weeks of supervised in-clinic balance training. The findings indicated that training with vibrotactile SA led to additional body sway reduction for balance exercises with head movements, and the improvements were retained for up to six months. Training with vibrotactile SA did not lead to significant additional improvements in the majority of the clinical outcomes except for the Activities-specific Balance Confidence scale. The study among older adults provided semi-supervised in-home balance rehabilitation training using a novel smartphone balance trainer. After completing eight weeks of balance training, participants who trained with vibrotactile SA showed significantly greater improvements in standing-related clinical outcomes, but not in gait-related clinical outcomes, compared with those who trained without SA. In addition to investigating the effects of long-term balance training with SA, we sought to study the effects of vibrotactile display design on people’s reaction times to vibrational cues. Among the various factors tested, the vibration frequency and tactor type had relatively small effects on reaction times, while stimulus location and secondary cognitive task had relatively large effects. Factors affected young and older adults’ reaction times in a similar manner, but with different magnitudes. Lastly, we explored the potential for ML to inform balance exercise progression for future applications of unsupervised balance training. We mapped body motion data measured by wearable inertial measurement units to balance assessment ratings provided by physical therapists. By training a multi-class classifier using the leave-one-participant-out cross-validation method, we found approximately 82% agreement among trained classifier and physical therapist assessments. The findings of this dissertation suggest that vibrotactile SA can be used as a rehabilitation tool to further improve a subset of clinical outcomes resulting from supervised balance rehabilitation training. Specifically, individuals who train with a SA device may have additional confidence in performing balance activities and greater postural stability, which could decrease their fear of falling and fall risk, and subsequently increase their quality of life. This research provides preliminary support for the hypothesized mechanism that SA promotes the central nervous system to reweight sensory inputs. The preliminary outcomes of this research also provide novel insights for unsupervised balance training that leverage wearable technology and ML techniques. By providing both SA and ML-based balance assessment ratings, the smart wearable device has the potential to improve individuals’ compliance and motivation for in-home balance training.PHDMechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/143901/1/baotian_1.pd

Fractional Order State Feedback Control for Improved Lateral Stability of Semi-Autonomous Commercial Heavy Vehicles

With the growing development of autonomous and semi-autonomous large commercial heavy vehicles, the lateral stability control of articulated vehicles have caught the attention of researchers recently. Active vehicle front steering (AFS) can enhance the handling performance and stability of articulated vehicles for an emergency highway maneuver scenario. However, with large vehicles such tractor-trailers, the system becomes more complex to control and there is an increased occurrence of instabilities. This research investigates a new control scheme based on fractional calculus as a technique that ensures lateral stability of articulated large heavy vehicles during evasive highway maneuvering scenarios. The control method is first implemented to a passenger vehicle model with 2-axles based on the well-known “bicycle model”. The model is then extended and applied onto larger three-axle commercial heavy vehicles in platooning operations. To validate the proposed new control algorithm, the system is linearized and a fractional order PI state feedback control is developed based on the linearized model. Then using Matlab/Simulink, the developed fractional-order linear controller is implemented onto the non-linear tractor-trailer dynamic model. The tractor-trailer system is modeled based on the conventional integer-order techniques and then a non-integer linear controller is developed to control the system. Overall, results confirm that the proposed controller improves the lateral stability of a tractor-trailer response time by 20% as compared to a professional truck driver during an evasive highway maneuvering scenario. In addition, the effects of variable truck cargo loading and longitudinal speed are evaluated to confirm the robustness of the new control method under a variety of potential operating conditions

Physiological responses of 'Jonagold' apple (Malus domestica Borkh.) following postharvest 1-Methylcyclopropene (1-MCP) application

Storage technologies such as controlled atmosphere (CA) storage and recently 1-Methylcyclopropene (1-MCP) treatments have led to an all-year-round global supply of high qualitative apple fruit. As a consequence, pressure of competition between several apple growing areas is increasing and in the same way consumers demands and expectations for apple fruit quality. However, throughout storage fruit quality is generally preserved at a high level whereas conditions at several points throughout the distribution chain are often not adequate for fresh commodities. It is critically important to maintain consistently high fruit quality throughout the marketing period to the final consumer and that fruit quality at the point of sale meets consumer requirements. Although decision for purchasing apple fruit is mainly due to appearance and firmness, consumer are increasingly concerned about nutritional quality and health-protecting compounds in foods. The plant hormone ethylene influences many of the ripening processes in climacteric fruit such as apple. Several storage conditions, such as reduced storage temperatures, controlled storage atmospheres with low O2- and elevated CO2-concentrations and recently 1-MCP treatments are known methods to minimize ethylene biosynthesis, ethylene sensitivity and responses of harvested climacteric fruit and by that to slow metabolic changes during ripening. 1-MCP is an effective tool for maintaining fruit quality during storage and post-storage handling. 1-MCP, a synthetic unsaturated cyclic olefin, is thought to act as a competitive substance to ethylene, occupying the ethylene receptor site so that ethylene cannot bind. In general, 1-MCP is able to counteract ripening effects triggered by ethylene during and after storage by blocking its action in fruit rather than inhibiting its production. The present research project consists of three studies. The aim of the first study was to determine the effect of 1-MCP treatment, storage condition and ?duration on apple fruit quality and consumer acceptability. The second part of the study focused on the effect of 1-MCP treatment, storage condition and ?duration on climacteric characteristics of apple fruit. The effect of 1-MCP treatment, storage condition and ?duration on antioxidant capacity of apple fruit was studied in the third part of the research. ?Jonagold? apple fruit were picked at commercial maturity in 2004, 2005 and 2006. Fruit were treated with 1-MCP on the day of harvest (0 days after harvest, 0 DAH) in 2004 and 7 DAH in 2005 and 2006 and stored the following day either in cold storage, CA- or ultra low oxygen- (ULO) storage. Fruit was held in cold storage prior to commencement of storage in 2005 and 2006. After 2, 4 and 6 months in 2004/05, 3, 6 and 9 months in 2005/06 and 3 and 5 months in 2006/07 fruit samples from each storage atmosphere ± 1-MCP were removed. Fruit quality parameters were assessed after harvest, commencement of storage and after each sample removal in 2004/05, 2005/06 and 2006/07 following 10 days shelf-life at 20°C. Consumer preference mapping was performed after 3 and 5 months of cold- and ULO-storage in 2006/07. Shelf-life respiration rate and fruit ethylene production was measured after harvest, commencement of storage and after each sample removal in 2004/05 and 2005/06, respectively. In 2005/06 ATP and ADP concentration was additionally determined. Nutritional quality and health-protecting compounds were examined by means of ascorbic acid concentration (L-AA), phenolic compounds and total non-enzymatic antioxidant capacity in 2005/06 following 10 days shelf-life after harvest, commencement of storage and after each sample removal. The results of the first part of the study showed that fruit quality generally decreased during storage and shelf-life depending on 1-MCP treatments, storage condition and ?duration. However, 1-MCP delayed ripening more and maintained fruit quality better than CA- or even ULO-storage alone. In consumer preference mapping most consumers, regardless of age or gender, preferred the 1-MCP treated fruit from ULO-storage. This effect was particularly seen when fruit were stored longer. Though sensory evaluation studies are time-consuming and there might be some flaws and difficulties to generate representative results from consumer taste panels, they are a useful tool to assess food quality and consumer preference. The results of the second part of the study proved that 1-MCP is a potent antagonist in terms of reducing and delaying ethylene production and respiratory rise. Although CA- and ULO-storage reduced ethylene production significantly in ?Jonagold? apples, 1-MCP treatment inhibited ethylene biosynthesis and accompanied respiration rate more than CA- and ULO-storage alone. The present study clearly shows that apple fruit shall be exposed as soon as possible to 1-MCP treatment and appropriate storage conditions after harvest for achieving a maximum effect on reduction of climacteric characteristics and maintenance of postharvest and post-storage apple fruit quality. L-AA concentration significantly decreased during storage, irrespective of storage condition and 1-MCP treatment. At commencement of storage L-AA concentration in 1-MCP treated fruit was higher than in untreated control fruit. However, following 9 months of storage L-AA concentration was lower in all 1-MCP treated fruit when compared with untreated fruit. Vitamin C equivalent phenolic concentration and vitamin C equivalent antioxidant capacity (VCEAC) decreased after 6 months of storage and gradually increased again after 9 months of storage. 1-MCP treatment had no effect on phenolics and VCEAC, respectively. In general, the results of the third part of the study showed that the nutritional value of apple fruit was not influenced by 1-MCP and storage condition.Lagertechnologien wie CA-Lagerung (controlled atmosphere) und seit einiger Zeit Behandlungen mit 1-Methylcyclopropene (1-MCP) haben weltweit zu einem ganzjährigen Angebot an qualitativ hochwertigen Äpfeln geführt. Daraus folgt ein erhöhter Konkurrenzdruck zwischen den einzelnen Anbaugebieten und in gleicher Weise steigen auch die Ansprüche und Erwartungen der Konsumenten an die Qualität der Äpfel. Obwohl die Fruchtqualität während der Lagerung auf einem hohen Level erhalten werden kann, sind die Bedingungen in der weiteren Vermarktungskette nicht immer optimal für frische pflanzliche Erzeugnisse. Es ist besonders wichtig, dass die hohe Fruchtqualität auf dem gesamten Weg der Vermarktung ununterbrochen bis zum Endkonsumenten erhalten wird. Obwohl die Kaufentscheidung bei Äpfeln hauptsächlich vom Aussehen sowie der Festigkeit beeinflusst wird, sind die Konsumenten zunehmend interessiert am gesundheits- und ernährungsphysiologischen Wert der Nahrungsmittel. Das Pflanzenhormon Ethylen beeinflusst viele Reifeprozesse in klimakterischen Früchten, wie bei Apfel. Verschiedene Lagerbedingungen, wie reduzierte Lagertemperaturen und die Veränderung der Lageratmosphäre (CA-/ULO-Lagerung) sowie die Behandlung mit 1-MCP sind bekannte Methoden um Ethylensynthese, -empfindlichkeit und -wirkung bei geernteten klimakterischen Früchten zu reduzieren und so die Stoffwechselprozesse während der Reife zu verzögern. 1-MCP ist ein effektives Mittel zur Erhaltung der Fruchtqualität während der Lagerung sowie der nachfolgenden Vermarktung. 1-MCP, ein synthetisches, ungesättigtes, zyklisches Olefin, ist eine mit Ethylen konkurrierende Substanz, die die Rezeptoren besetzt, so dass Ethylen nicht andocken kann. Die Fähigkeit von 1-MCP, dem Reifeprozess entgegenzuwirken, ist mehr einer verhinderten Wirkung, als einer reduzierten Produktion von Ethylen zuzuschreiben. Das vorliegende Projekt besteht aus drei einzelnen Studien. Das Ziel der ersten Studie war es, den Einfluss einer 1-MCP-Behandlung und verschiedener Lagerbedingungen auf die Apfelfruchtqualität sowie die Akzeptanz dieser Früchte beim Konsumenten zu untersuchen. Der zweite Teil der Studie befasste sich mit den Auswirkungen einer 1-MCP-Behandlung und verschiedenen Lagerbedingungen auf die klimakterischen Merkmale bei Apfel. Im dritten Teil des vorliegenden Projektes wurde der Einfluss einer 1-MCP-Behandlung in Kombination mit verschiedenen Lagerbedingungen auf die antioxidative Kapazität von Äpfeln untersucht. ?Jonagold?-Äpfel wurden in den Jahren 2004, 2005 und 2006 in einem für Langzeitlagerung üblichen Reifezustand geerntet. Nach der Behandlung mit 1-MCP am Tag der Ernte in 2004 und 7 Tage nach der Ernte in 2005 und 2006 wurden die Früchte am folgenden Tag im Kühllager, CA- bzw. ULO-Lager eingelagert. Nach 2, 4 und 6 Monaten in 2004/05 und nach 3, 6 und 9 Monaten in 2005/06 sowie nach 3 und 5 Monaten in 2006/07 wurden aus jedem Lager ± 1-MCP Früchte entnommen. Fruchtqualitätsfaktoren wurden nach der Ernte, Einlagerung sowie nach jeder Probenahme jeweils nach 10 Tagen Nachlagerung (20°C) in allen drei Versuchsjahren analysiert. Zusätzliche Verkostungen wurden nach 3 und 5 Monaten Kühl- bzw. ULO-Lagerung in 2006/07 durchgeführt. Die Atmungsrate sowie die Ethylenproduktion der Früchte wurde nach der Ernte, Einlagerung sowie nach jeder Probenahme in 2004/05 und 2005/06 gemessen. In 2005/06 wurden zusätzlich die ATP und ADP-Konzentrationen bestimmt. Zur Bestimmung der gesundheits- und ernährungsphysiologisch wertvollen Bestandteile wurden in 2005/06 die Vitamin C-Konzentration, die Gesamtphenole sowie die Vitamin-C äquivalente antioxidative Kapazität (VCEAC) der Äpfel 10 Tage nach der Ernte, Einlagerung sowie nach jeder Auslagerung analysiert. Die Ergebnisse der ersten Studie zeigten, dass die Fruchtqualität grundsätzlich nach Lagerung und Shelf-life in Abhängigkeit von 1-MCP-Behandlung und Lagerbedingungen abnimmt. Die meisten Konsumenten, unabhängig von Alter und Geschlecht, bevorzugten die mit 1-MCP behandelten und im ULO-Lager gelagerten Früchten. Dieser Effekt war besonders deutlich nach längerer Lagerung festzustellen. Sensorische Untersuchungen sind sehr zeitaufwändig und es kann schwierig sein, bei Konsumentenbefragungen repräsentative Ergebnisse zu erhalten. Dennoch sind sie ein hilfreiches Mittel, um Qualität und geschmacklichen Wert der Früchte sowie die Ansprüche und Zufriedenheit der Konsumenten zu ermitteln. In der zweiten Studie konnte festgestellt werden, dass 1-MCP die Ethylenproduktion sowie den Atmungsanstieg bei Apfel deutlich reduziert und verzögert. Obwohl die Ethylenproduktion von ?Jonagold?-Äpfeln auch durch CA- und ULO-Lagerung signifikant reduziert wurde, verminderte eine Behandlung mit 1-MCP die Ethylenbiosynthese sowie den Atmungsanstieg stärker als CA- und ULO-Lagerung allein. Die vorliegenden Ergebnisse zeigen deutlich, dass es besonders wichtig ist, die Äpfel möglichst bald nach der Ernte mit 1-MCP zu behandeln und einzulagern. Nur so kann ein maximaler Effekt auf die klimakterischen Parameter sowie die Erhaltung der Fruchtqualität während und nach der Lagerung erzielt werden. Unabhängig von Lageratmosphäre und 1-MCP-Behandlung war während der Lagerung von ?Jonagold?-Äpfeln eine signifikante Reduktion der Vitamin C-Gehalte festzustellen. Obwohl die Vitamin-C-Konzentration in den mit 1-MCP-behandelten Früchten bei der Einlagerung höher war als in den unbehandelten Kontrollfrüchten, war nach 9 Monaten Lagerung im Vergleich zu den Kontrollfrüchten in allen mit 1-MCP behandelten Früchten eine niedrigere Vitamin C-Konzentration festzustellen. Gesamtphenolkonzentration und VCEAC verringerten sich während der ersten 6 Lagermonate, um dann nach 9 Monaten Lagerung wieder anzusteigen. Die Behandlung mit 1-MCP und verschiedene Lagerkonditionen hatten keinen Einfluss auf Phenole und VCEAC