Temporally scattered brain: neural mechanism apprehending the paradox of the discrete and continuous flow of consciousness

In dieser Dissertation werden offene Fragen über „Bewußtsein“ aus neurowissenschaftlicher, psychologischer und auch philosophischer Sicht erörtert. Es geht insbesondere darum, wie in traditionellen und modernen Ansätzen die Beziehung von zeitlicher Informations-Verarbeitung und Repräsentationen im Bewußtsein konzipiert werden. In einer historischen Aufarbeitung wird gezeigt, dass Zeit als mentale Kategorie in der psychologischen und neurowissenschaftlichen Forschung lange eher vernachlässigt worden ist, was sich erst jetzt zu ändern scheint. Wie wichtig Informations-Verarbeitung im Zeitbereich für ein besseres Verständnis von Bewußtseinsprozessen ist, wird herausgearbeitet, denn alle Verhaltensweisen und alles bewußte Erleben haben notwendigerweise eine zeitliche Charakteristik. Die grundsätzliche aber bisher nicht hinreichend beantwortete Frage ist, ob diese Charakteristik, die Informations-Verarbeitung in der Zeit, als kontinuierlich oder als diskret zu verstehen ist. Neue Befunde legen nahe, dass so genannte „Zeitfenster“ bestimmter Dauer notwendig sind, um neuronale Informations-Verarbeitung zu ermöglichen, damit Bewußtseinsprozesse überhaupt entstehen können. Wenn aber diskrete Zeitfenster notwendig sind, dann stellt sich die weitere Frage, wie es paradoxerweise zum subjektiven Eindruck einer zeitlichen Kontinuität zum Beispiel in der Wahrnehmung kommen kann. Das Erleben zeitlicher Kontinuität bezieht sich nicht nur auf Prozesse der Wahrnehmng und des Erlebens, sondern auch auf den viel weiteren Rahmen der Kontinuität personaler Identität. Es wird darauf hingewiesen, dass diese Kontinuität bei bestimmten Erkrankungen oder veränderten Bewußtseinszuständen verloren gehen kann. Ein derartiger Verlust legt nahe, dass es aktive Mechanismen auf neuronaler Ebene geben sollte, die personale Identität über die Zeit hinweg erzeugen. Es mußt gleichsam ein „Klebstoff“ vermutet werden, der zeitlich Diskretes in anschauliche Kontinuität verwandelt. Mechanismen, die hierfür in Frage kommen könnten, sind bisher nicht bekannt. Ein erster Versuch zur Aufklärung dieser Frage wird mit einem fMRT-Experiment gemacht, in dem visuelle und auditive Vorstellungen untersucht werden. Hier zeigt sich, dass in beiden Modalitäten gemeinsame neuronale Aktivierungen in bestimmten Hirnstrukturen zu beobachten sind, was möglicherweise einen ersten Hinweis auf die Erzeugung von anschaulicher Kontinuität geben könnte. Des weiteren wird am Ende der Arbeit auf die Bedeutung des Reafferenzprinzips hingewiesen, das vielleicht einen neuen Ansatz zum besseren Verständnis mancher Phänomene wie des Déjà Vu geben könnte, wenn man in dieses klassische Prinzip einen Zeitfaktor integriert, was bisher theoretisch nicht geschehen ist. Während der Fokus der Arbeit auf theoretischen Konzepten zu Zeit und Bewußtsein im psychologischen, neurowissenschaftlichen und philosophischen Kontext liegt, werden auch Bezüge zu den Künsten, der Dichtkunst und der Musik, offen gelegt. Dies soll darauf hinweisen, dass die Beziehung zwischen der „Zeit des Menschen“ und dem bewußten Erleben ein Menschheitsthema ist, das über den wissenschhaftlichen Rahmen hinaus weist.In this dissertation open questions about “consciousness” are discussed from a psychological, neuroscientific and also philosophical perspective. In particular, it is described how the relationship between temporal information processing and conscious representations is conceived in traditional and modern approaches. In a historical review it is shown that time as a mental category has been neglected for a long time in psychological and neuroscientific research, although this is changing recently. The importance of temporal information processing for a better understanding of conscious processes is analyzed because any behavior and all subjective experiences necessarily have a temporal characteristic. There is, however, a basic and still open question whether this characteristic, i.e., temporal information processing, is continuous or discrete. New research suggests that “time windows” of specific durations are necessary in neural information processing being the basis for conscious representations. If, however, discrete time windows are necessary the question arises how paradoxically the subjective impression of temporal continuity for instance in perception is possible. The impression of temporal continuity refers, however, not only to processes of perception and experience, but in a broader context also to the continuity of personal identity. It is indicated that this continuity can break down in certain diseases or in altered states of consciousness. Such losses suggest the existence of active mechanisms on the neural level which allow for the creation of personal identity across time. Some kind of “glue” has to be suspected that transforms what is temporally discrete into apparent continuity. Potential mechanisms for this transformation are still not known. A first attempt is made to answer this question with an fMRI-experiment in which visual and auditory images are analyzed. For both modalities’ common activations in certain brain regions are observed which possibly might be a first indication about a mechanism creating apparent continuity. At the end of the dissertation the importance of the reafference principle is stressed as it may provide a new perspective towards a better understanding of some phenomena like Déja Vu, if one includes in this classical principle a temporal factor which theoretically has not been done yet. Although the focus of the dissertation lies on theoretical concepts of time and consciousness within a psychological, neuroscientific and philosophical context, some links to the arts like poetry and music are made transparent. This shall indicate that the relationship between the “time of humans” and conscious experiences is a topic of humankind that goes beyond the scientific frame

VISUALIZATION OF ULTRASOUND INDUCED CAVITATION BUBBLES USING SYNCHROTRON ANALYZER BASED IMAGING

Ultrasound is recognized as the fastest growing medical modality for imaging and therapy. Being noninvasive, painless, portable, X-ray radiation-free and far less expensive than magnetic resonance imaging, ultrasound is widely used in medicine today. Despite these benefits, undesirable bioeffects of high-frequency sound waves have raised concerns; particularly, because ultrasound imaging has become an integral part of prenatal care today and is increasingly used for therapeutic applications. As such, ultrasound bioeffects must be carefully considered to ensure optimal benefits-to-risk ratio. In this context, few studies have been done to explore the physics (i.e. ‘cavitation’) behind the risk factors. One reason may be associated with the challenges in visualization of ultrasound-induced cavitation bubbles in situ. To address this issue, this research aims to develop a synchrotron-based assessment technique to enable visualization and characterization of ultrasound-induced microbubbles in a physiologically relevant medium under standard ultrasound operating conditions. The first objective is to identify a suitable synchrotron X-ray imaging technique for visualization of ultrasound-induced microbubbles in water. Two synchrotron X-ray phase-sensitive imaging techniques, in-line phase contrast imaging (PCI) and analyzer-based imaging (ABI), were evaluated. Results revealed the superiority of the ABI method compared to PCI for visualization of ultrasound-induced microbubbles. The second main objective is to employ the ABI method to assess the effects of ultrasound acoustic frequency and power on visualization and mapping of ultrasound-induced microbubble patterns in water. The time-averaged probability of ultrasound-induced microbubble occurrence along the ultrasound beam propagation in water was determined using the ABI method. Results showed the utility of synchrotron ABI for visualizing cavitation bubbles formed in water by clinical ultrasound systems working at high frequency and output powers as low as used for therapeutic systems. It was demonstrated that the X-ray ABI method has great potential for mapping ultrasound-induced microbubble patterns in a fluidic environment under different ultrasound operating conditions of clinical therapeutic devices. Taken together, this research represents an advance in detection techniques for visualization and mapping of ultrasound-induced microbubble patterns using the synchrotron X-ray ABI method without usage of contrast agents. Findings from this research will pave the road toward the development of a synchrotron-based detection technique for characterization of ultrasound-induced cavitation microbubbles in soft tissues in the future

DEVELOPMENT OF NANOPARTICLE RATE-MODULATING AND SYNCHROTRON PHASE CONTRAST-BASED ASSESSMENT TECHNIQUES FOR CARDIAC TISSUE ENGINEERING

Myocardial infarction (MI) is the most common cause of heart failure. Despite advancements in cardiovascular treatments and interventions, current therapies can only slow down the progression of heart failure, but not tackle the progressive loss of cardiomyocytes after MI. One aim of cardiac tissue engineering is to develop implantable constructs (e.g. cardiac patches) that provide physical and biochemical cues for myocardium regeneration. To this end, vascularization in these constructs is of great importance and one key issue involved is the spatiotemporal control of growth-factor (GF)-release profiles. The other key issue is to non-invasively quantitatively monitor the success of these constructs in-situ, which will be essential for longitudinal assessments as studies are advanced from ex-vivo to animal models and human patients. To address these issues, the present research aims to develop nanoparticles to modulate the temporal control of GF release in cardiac patches, and to develop synchrotron X-ray phase contrast tomography for visualization and quantitative assessment of 3D-printed cardiac patch implanted in a rat MI model, with four specific objectives presented below. The first research objective is to optimize nanoparticle-fabrication process in terms of particle size, polydispersity, loading capacity, zeta potential and morphology. To achieve this objective, a comprehensive experimental study was performed to examine various process parameters used in the fabrication of poly(lactide-co-glycolide) (PLGA) nanoparticles, along with the development of a novel computational approach for the nanoparticle-fabrication optimization. Results show that among various process parameters examined, the polymer and the external aqueous phase concentrations are the most significant ones to affect the nanoparticle physical and release characteristics. Also, the limitations of PLGA nanoparticles such as initial burst effect and the lack of time-delayed release patterns are identified. The second research objective is to develop bi-layer nanoparticles to achieve the controllable release of GFs, meanwhile overcoming the above identified limitations of PLGA nanoparticles. The bi-layer nanoparticle is composed of protein-encapsulating PLGA core and poly(L-lactide) (PLLA)-rate regulating shell, thus allowing for low burst effect, protein structural integrity and time-delayed release patterns. The bi-layer nanoparticles, along with PLGA ones, were successfully fabricated and then used to regulate simultaneous and/or sequential release of multiple angiogenic factors with the results demonstrating that they are effective to promote angiogenesis in fibrin matrix. The third objective is to develop novel mathematical models to represent the controlled-release of bioactive agents from nanoparticles. For this, two models, namely the mechanistic model and geno-mechanistic model, were developed based on the local and global volume averaging approaches, respectively, and then validated with experiments on both single- and bi-layer nanoparticles, by which the ovalbumin was used as a protein model for the release examination. The results illustrates the developed models are able to provide insight on the release mechanism and to predict nanoparticle transport and degradation properties of nanoparticles, thus providing a means to regulate and control the release of bioactive agents from the nanoparticles for tissue engineering applications. The fourth objective of this research is to develop a synchrotron-based phase contrast non-invasive imaging technique for visualization and quantitative assessment of cardiac patch implanted in a rat MI model. To this end, the patches were created from alginate strands using the three-dimensional (3D) printing technique and then surgically implanted on rat hearts for the assessment based on phase contrast tomography. The imaging of samples was performed at various sample-to-detector distances, CT-scan time, and areas of the region of interest (ROI) to examine their effects on imaging quality. Phase-retrieved images depict visible and quantifiable structural details of the patch at low radiation dose, which, however, are not seen from the images by means of dual absorption-phase and a 3T clinical magnetic resonance imaging. Taken together, this research represents a significant advance in cardiac tissue engineering by developing novel nano-guided approaches for vascularization in myocardium regeneration as well as non-invasive and quantitative monitoring techniques for longitudinal studies on the cardiac patch implanted in animal model and eventually in human patients

Centaur Mind: A Glimpse into an Integrative Structure of Consciousness

Jean Gebser’s theory of consciousness suggests that we are experiencing a new era in the history of consciousness. Human consciousness moves like a pendulum. The current Integral Structure of Consciousness is not unprecedented, yet we are experiencing it in a multi-layered, deeper, and vaster way. Centaurs are imaginal creatures that first appeared within the Mythical Structure of Consciousness, making a bridge between the unity of the Magical and the duality of Mental structures. In this paper, I view the centaurs through the lenses of mythology and archetypal depth psychology and discuss the critical role of this mythic figure in the integration between the civil and the primitive aspects of human consciousness. Centaurs have always been about integration with our animalistic side, but are they bringing a specifically necessary gift to our time of integral consciousness? Are centaurs returning to human consciousness? If so, should we and can we create a more integrated centaur myth

Modeling and analysis of actual evapotranspiration using data driven and wavelet techniques

Large-scale mining practices have disturbed many natural watersheds in northern Alberta, Canada. To restore disturbed landscapes and ecosystems’ functions, reconstruction strategies have been adopted with the aim of establishing sustainable reclaimed lands. The success of the reconstruction process depends on the design of reconstruction strategies, which can be optimized by improving the understanding of the controlling hydrological processes in the reconstructed watersheds. Evapotranspiration is one of the important components of the hydrological cycle; its estimation and analysis are crucial for better assessment of the reconstructed landscape hydrology, and for more efficient design. The complexity of the evapotranspiration process and its variability in time and space has imposed some limitations on previously developed evapotranspiration estimation models. The vast majority of the available models estimate the rate of potential evapotranspiration, which occurs under unlimited water supply condition. However, the rate of actual evapotranspiration (AET) depends on the available soil moisture, which makes its physical modeling more complicated than the potential evapotranspiration. The main objective of this study is to estimate and analyze the AET process in a reconstructed landscape. Data driven techniques can model the process without having a complete understanding of its physics. In this study, three data driven models; genetic programming (GP), artificial neural networks (ANNs), and multilinear regression (MLR), were developed and compared for estimating the hourly eddy covariance (EC)-measured AET using meteorological variables. The AET was modeled as a function of five meteorological variables: net radiation (Rn), ground temperature (Tg), air temperature (Ta), relative humidity (RH), and wind speed (Ws) in a reconstructed landscape located in northern Alberta, Canada. Several ANN models were evaluated using two training algorithms of Levenberg-Marquardt and Bayesian regularization. The GP technique was employed to generate mathematical equations correlating AET to the five meteorological variables. Furthermore, the available data were statistically analyzed to obtain MLR models and to identify the meteorological variables that have significant effect on the evapotranspiration process. The utility of the investigated data driven models was also compared with that of HYDRUS-1D model, which is a physically based model that makes use of conventional Penman-Monteith (PM) method for the prediction of AET. HYDRUS-1D model was examined for estimating AET using meteorological variables, leaf area index, and soil moisture information. Furthermore, Wavelet analysis (WA), as a multiresolution signal processing tool, was examined to improve the understanding of the available time series temporal variations, through identifying the significant cyclic features, and to explore the possible correlation between AET and the meteorological signals. WA was used with the purpose of input determination of AET models, a priori. The results of this study indicated that all three proposed data driven models were able to approximate the AET reasonably well; however, GP and MLR models had better generalization ability than the ANN model. GP models demonstrated that the complex process of hourly AET can be efficiently modeled as simple semi-linear functions of few meteorological variables. The results of HYDRUS-1D model exhibited that a physically based model, such as HYDRUS-1D, might perform on par or even inferior to the data driven models in terms of the overall prediction accuracy. The developed equation-based models; GP and MLR, revealed the larger contribution of net radiation and ground temperature, compared to other variables, to the estimation of AET. It was also found that the interaction effects of meteorological variables are important for the AET modeling. The results of wavelet analysis demonstrated the presence of both small-scale (2 to 8 hours) and larger-scale (e.g. diurnal) cyclic features in most of the investigated time series. Larger-scale cyclic features were found to be the dominant source of temporal variations in the AET and most of the meteorological variables. The results of cross wavelet analysis indicated that the cause and effect relationship between AET and the meteorological variables might vary based on the time-scale of variation under consideration. At small time-scales, significant linear correlations were observed between AET and Rn, RH, and Ws time series, while at larger time-scales significant linear correlations were observed between AET and Rn, RH, Tg, and Ta time series

A POROUS MEDIA APPROACH TOWARDS A DYNAMIC MECHANISTIC MODEL OF DRUG ELIMINATION BY THE LIVER

Hepatic drug elimination is a major PK process contributing to loss of drug concentration in the body. The prediction of hepatic clearance (and hence drug concentrations in the body) requires an understanding of the physiology and mechanisms of the hepatic elimination process and their compilation into a mechanistic model. Several physiological models including well-stirred model, parallel tube model and dispersion model have been developed to describe the hepatic elimination process and to determine how physiological variables such as blood flow, unbound fraction and enzyme activity may influence the hepatic clearance. However, each model has distinguishing advantages and limitations, which lead sometimes to very disparate prediction outcomes. Although hepatic drug elimination has been mathematically described by different physiological models, the mass transfer phenomena in the liver has not been described from a porous media viewpoint using local volume averaging method. The inherently porous structure of the liver allows us to describe the hepatic drug elimination process based on a porous media approach such that structural properties of the liver tissue, physico-chemical properties of the drug as well as transport properties associated with the hepatic blood perfusion are included in the model. Applying local volume averaging method and local equilibrium to the liver as a porous medium, a governing partial differential equation which takes into account liver porosity, tortuosity, permeability, unbound drug fraction and hepatic tissue partition coefficient, drug-plasma diffusivity, axial/radial dispersion and hepatocellular metabolism parameters was developed. The governing equation was numerically solved using implicit finite difference and Gauss-Seidel iterative method in order to describe changes in dug concentration with time and position across the liver following an intravenous drug administration. The model was used to predict hepatic clearance and bioavailability, which were then compared to reported observations. The predicted values of hepatic clearance and bioavailability had good agreement with the reported observations for high and low clearance drugs. As well, the model was able to successfully predict an unsteady state of hepatic drug elimination with concentration dependent intrinsic clearance. When statistically compared to the well-stirred, parallel tube and dispersion models the proposed model suggested a smaller mean squared prediction error and very good agreement to reported observations for eight drugs. A sensitivity analysis revealed that an increase in liver porosity results in a slight decrease in the drug concentration gradient across the liver while higher tissue partition coefficient values increase the concentration gradient. The model also suggested that the bioavailability was sensitive to the interaction between unbound fraction and intrinsic clearance. This study indicates that the liver and hepatic drug elimination can be successfully explored from a porous media viewpoint and may provide better mechanistic predictions of drug elimination processes by the liver

DEVELOPMENT OF HYBRID-CONSTRUCT BIOPRINTING AND SYNCHROTRON-BASED NON-INVASIVE ASSESSMENT TECHNIQUES FOR CARTILAGE TISSUE ENGINEERING

Cartilage tissue engineering has been emerging as a promising therapeutic approach, where engineered constructs or scaffolds are used as temporary supports to promote regeneration of functional cartilage tissue. Hybrid constructs fabricated from cells, hydrogels, and solid polymeric materials show the most potential for their enhanced biological and mechanical properties. However, fabrication of customized hybrid constructs with impregnated cells is still in its infancy and many issues related to their structural integrity and the cell functions need to be addressed by research. Meanwhile, it is noticed that nowadays monitoring the success of tissue engineered constructs must rely on animal models, which have to be sacrificed for subsequent examination based on histological techniques. This becomes a critical issue as tissue engineering advances from animal to human studies, thus raising a great need for non-invasive assessments of engineered constructs in situ. To address the aforementioned issues, this research is aimed to (1) develop novel fabrication processes to fabricate hybrid constructs incorporating living cells (hereafter referred as “construct biofabrication”) for cartilage tissue regeneration and (2) develop non-invasive monitoring methods based on synchrotron X-ray imaging techniques for examining cartilage tissue constructs in situ. Based on three-dimensional (3D) printing techniques, novel biofabrication processes were developed to create constructs from synthetic polycaprolactone (PCL) polymer framework and cell-impregnated alginate hydrogel, so as to provide both structural and biological properties as desired in cartilage tissue engineering. To ensure the structural integrity of the constructs, the influence of both PCL polymer and alginate was examined, thus forming a basis to prepare materials for subsequent construct biofabrication. To ensure the biological properties, three types of cells, i.e., two primary cell populations from embryonic chick sternum and an established chondrocyte cell line of ATDC5 were chosen to be incorporated in the construct biofabrication. The biological performance of the cells in the construct were examined along with the influence of the polymer melting temperature on them. The promising results of cell viability and proliferation as well as cartilage matrix production demonstrate that the developed processes are appropriate for fabricating hybrid constructs for cartilage tissue engineering. To develop non-invasive in situ assessment methods for cartilage and other soft tissue engineering applications, synchrotron phase-based X-ray imaging techniques of diffraction enhanced imaging (DEI), analyzer based imaging (ABI), and inline phase contrast imaging (PCI) were investigated, respectively, with samples prepared from pig knees implanted with low density scaffolds. The results from the computed-tomography (CT)-DEI, CT-ABI, and extended-distance CT-PCI showed the scaffold implanted in pig knee cartilage in situ with structural properties more clearly than conventional PCI and clinical MRI, thus providing information and means for tracking the success of scaffolds in tissue repair and remodeling. To optimize the methods for live animal and eventually for human patients, strategies with the aim to reduce the radiation dose during the imaging process were developed by reducing the number of CT projections, region of imaging, and imaging resolution. The results of the developed strategies illustrate that effective dose for CT-DEI, CT-ABI, and extended-distance CT-PCI could be reduced to 0.3-10 mSv, comparable to the dose for clinical X-ray scans, without compromising the image quality. Taken together, synchrotron X-ray imaging techniques were illustrated promising for developing non-invasive monitoring methods for examining cartilage tissue constructs in live animals and eventually in human patients

Efficient Extraction of Phenolic Compounds from Wheat Distiller's Dried Grain; Ultrasound Pretreatment and Dielectric Studies

Phenolic compounds are useful bioactive molecules with important medicinal properties. Wheat dried distillers grain (DDG), a coproduct of the ethanol production process, is rich in potentially health-promoting phenolic compounds. As the concentration of natural medicinal compounds (e.g. phenolic compounds) in plant materials (e.g. DDG) is low, an efficient solid-solvent extraction process would improve their solubility and effective diffusivity. In the extraction of phenolic compounds from DDG, the DDG cell wall is an important barrier for mass transfer from inside to outside the cell. High-power ultrasound pretreatment of plant material (e.g. DDG) can break down the cell wall and increase the extraction rate and yield of natural medicinal compounds (e.g. phenolic compounds). Radio frequency (RF) heating can provide uniform internal heating of all particles and solvent in the packed-bed extraction unit which results in improved, uniform solubility of the solute in the solvent and diffusivity of the desired compound without overheating specific areas. The kinetics and mechanism of the extraction were studied and the rate constant of extraction, the saturated concentration, the activation energies, and the temperature independent factors of solid-liquid extraction of phenolic compounds from DDG under different extraction conditions were determined, assuming second-order extraction kinetics. The effect of particle moisture content, ethanol fraction of solvent and extraction temperature on the kinetics, rate and yield of extraction were analyzed. The results of these calculations were compared and discussed with a view to optimizing the extraction process. The maximum extraction rate and yield were obtained with 70% ethanol concentration, 70°C extraction temperature and 59% particle moisture content (w.b.). The effective diffusivity of phenolic compounds in DDG particles was also determined for each extraction condition. The effect of high-power ultrasound pretreatment on destruction of DDG cell walls and the extraction yield and rate was investigated. Direct sonication by an ultrasound probe horn at 24 kHz was applied and factors such as ultrasound power, treatment time and consumed energy were investigated. The effect of ultrasound on destruction of DDG cell walls was studied by characterizing the physical properties (specific surface area, pore volume and pore size) of the untreated and treated samples at different levels of ultrasound power and treatment time using the method of nitrogen (N2) adsorption at 77 K. The increased surface area, pore volume, pore size, and extraction yield and rate after ultrasonic treatment showed the positive effect of ultrasound pretreatment on breaking down cell walls and pore developement. Among tested ultrasound conditions, 100% ultrasound power for 30 seconds was determined to be the best pretreatment with appropriate consumed energy compared to other tested conditions. Under this extraction condition a 14.29% increase in extraction yield was observed compared to the control, and the BET (Brunauer, Emmett, and Teller) surface and extraction rate constant increased from 13.90 to 18.85 m2/g and 0.057 to 3.933 Lg-1min-1, respectively. The dielectric properties of the packed bed of wheat DDG particles with ethanol/water solution were measured for more than eight different frequencies using a precision LCR (inductance, capacitance and resistance) meter and a liquid test fixture. The power penetration depth of the packed bed was measured for all applied experimental conditions at 13.56 and 27.12 MHz. The effect of the ethanol fraction of the solvent, moisture content of the DDG particle and temperature on the dielectric constant, loss factor and power penetration depth were investigated. Both the dielectric constant and the loss factor of the packed decreased with frequency for all levels of ethanol fractions and temperatures. The dielectric constant and loss factor of the bed increased with temperature for all levels of particle moisture content and ethanol fraction; however, for the particle moisture content of 0.0373 d.b. with 100% and 70% ethanol, and also for the particle moisture content of 1.58 d.b. with 100% ethanol, the effect of temperature on the dielectric constant was insignificant. The dielectric constant and loss factor of the packed bed were significantly decreased with ethanol volumetric fraction of solvent for all levels of temperature and particle moisture content. The dielectric constant and loss factor increased with moisture content for 40%, 70% and 100% ethanol; however, for 0% ethanol, the effect of moisture content was not significant. Power penetration depth decreased with temperature, and particle moisture content increased with ethanol fraction. Multiple regression equations for the dielectric constant and dielectric loss factor of the packed bed were developed for frequencies of 13.56 and 27.12 MHz. The dielectric properties of the packed beds with solvent in this study assure the possibility of applying RF-assisted extraction for extraction of phenolic compounds from DDG