Development of computer application for determination of chemical diffusion properties in biological tissues

The main objective of this work was to develop an application capable of determining the diffusion times and diffusion coefficients of optical clearing agents and water inside a known type of muscle. Different types of chemical agents can also be used with the method implemented, such as medications or metabolic products. Since the diffusion times can be calculated, it is possible to describe the dehydration mechanism that occurs in the muscle. The calculation of the diffusion time of an optical clearing agent allows to characterize the refractive index matching mechanism of optical clearing. By using both the diffusion times and diffusion of water and clearing agents not only the optical clearing mechanisms are characterized, but also information about optical clearing effect duration and magnitude is obtained. Such information is crucial to plan a clinical intervention in cooperation with optical clearing. The experimental method and equations implemented in the developed application are described in throughout this document, demonstrating its effectiveness. The application was developed in MATLAB code, but the method was personalized so it better fits the application needs. This process significantly improved the processing efficiency, reduced the time to obtain he results, multiple validations prevents common errors and some extra functionalities were added such as saving application progress or export information in different formats. Tests were made using glucose measurements in muscle. Some of the data, for testing purposes, was also intentionally changed in order to obtain different simulations and results from the application. The entire project was validated by comparing the calculated results with the ones found in literature, which are also described in this document.

Up-Link/Down-Link capacity Unbalance analysis in UMTS using a GIS based Planning Tool and MATLAB simulation

Capacity analysis using simulation is not a new thing in literature. Most of the development process of UMTS standardization have used simulation tools; however, we thing that the use of GIS planning tools and matrix manipulation capacity of MATLAB can show us different scenarios and make a more realistic analysis. Some work is been doing in COST 273 in order to have more realistic scenarios for UMTS planning. Our work initially was centered in uplink analysis, but we are now working in downlink analysis, specifically in two areas: capacity in number of users for RT and NRT services, and Node B power. In this work we will show results for up-link capacity and some results for downlink capacity and BS power consumption.

Legalities of treating wildlife in UK veterinary practice.

Many different species of wildlife will be presented to veterinary practices. In addition to providing care for these patients, veterinary nurses need to be aware of the legal aspects that apply. Legislation relating to wildlife species is particularly relevant to taking animals from the wild, keeping wild animals and birds in care, releasing them back into the wild and notifiable diseases. Following devolution, there are some differences in legislation in different parts of the UK. Specific species, particularly endangered species, have more detailed legislation which also needs to be adhered to. While lay people may have the best of intentions, they need to be aware that all veterinary care needs to follow Schedule 3 of the Veterinary Surgeon's Act 1966, and the best interests of the animals must be central to all care that is given.

Changes in catches and biological characteristics of Nile tilapia (Oreochromis niloticus Linnaeus) in Lake Wamala (Uganda) under changing climatic conditions

There have been changes in catches and biological characteristics of the Nile Tilapia, Oreochromis niloticus (Linnaeus) in Lake Wamala (Uganda) since its introduction and establishment, but the factors which have contributed to these changes are not adequately understood. This study examined changes in catches and biological characteristics of Nile tilapia in relation to changes in temperature, rainfall and lake depth to provide an understanding of the role of changing climatic conditions. There was an increase in minimum, maximum and average temperature since 1980, but only minimum (0.021ºCyr-1) and average (0.018ºCyr-1) showed a significant trend (p < 0.05). Rainfall increased by 8.25 mmyr-1 since 1950 and accounted for 79.5% of the water input into the lake while evaporation accounted for 86.2% of the water loss from the lake. The lake depth was above 4 m during the years rainfall was above normal average of 1180 mm, except during the period 2011-2014. The contribution of Nile tilapia to total catch and CPUE changed with rainfall and lake depth up to 2000, after which they decreased despite increase in rainfall. There was a strong positive correlation between lake depth and average total length of Nile tilapia (r = 0.991, p < 0.001) and length at 50% maturity (r = 0.726, p < 0.001). The length-weight allometry between high and low lake depths was significantly different [t (6) = 3.225, p < 0.05], with Nile tilapia being heavier (for a given length) at high lake depth than at low lake depth. Fecundity of Nile tilapia was higher and egg diameter lower than what is reported in literature. Nile tilapia shifted from algal dominated diet during the wet season to include more insects during the dry season. The study showed that the catches and biological characteristics of Nile tilapia change with climate and hydrological factors and these need to be considered in management of the fisheries of Lake Wamala.

An investigation of the clinical utility of preoperative cardiopulmonary exercise testing in patients undergoing major pancreatic surgery

Pancreaticoduodenectomy with or without adjuvant chemotherapy remains the only modality of possible cure in patients with cancer involving the head of the pancreas and the periampullary region. While mortality rates after pancreaticoduodenectomy have improved considerably over the course of the last century, morbidity remains high. Patient selection is of paramount importance in ensuring that major surgery is offered to individuals who will most benefit from a pancreaticoduodenectomy. Moreover, identifying preoperative risk factors provides potential targets for prehabilitation and optimisation of the patient's physiology before undertaking surgery. In addition to this, early identification of patients who are likely to develop postoperative complications allows for better allocation of critical care resources and more aggressive management high risk patients. Cardiopulmonary exercise testing is becoming an increasingly popular tool in the preoperative risk assessment of the surgical patient. However, very little work has been done to investigate the role of cardiopulmonary exercise testing in predicting complications after pancreaticoduodenectomy. The impact of jaundice, systemic inflammation and other preoperative clinicopathological characteristics on cardiopulmonary exercise physiology has not been studied in detail before in this cohort of patients. The overall aim of the thesis was to examine the relationships between preoperative clinico-pathological characteristics including cardiopulmonary exercise physiology, obstructive jaundice, body composition and systemic inflammation and complications and the post-surgical systemic inflammatory response in patients undergoing pancreaticoduodenectomy. Chapter 1 reviews the existing literature on preoperative cardiopulmonary exercise testing, the impact of obstructive jaundice, perioperative systemic inflammation and the importance of body composition in determining outcomes in patients undergoing major surgery with particular reference to pancreatic surgery. Chapter 2 reports on the role of cardiopulmonary exercise testing in predicting postoperative complications after pancreaticoduodenectomy. The results demonstrate that patients with V˙O2AT less than 10 ml/kg/min are more likely to develop a postoperative pancreatic fistula, stay longer in hospital and less likely to receive adjuvant therapy. These results emphasise the importance of aerobic fitness to recover from the operative stress of major surgery without significant morbidity. Cardiopulmonary exercise testing may prove useful in selecting patients for intensive prehabilitation programmes as well as for other optimisation measures to prepare them for major surgery. Chapter 3 evaluates the relationship between cardiopulmonary exercise physiology and other clinicopathological characteristics of the patient. A detailed analysis of cardiopulmonary exercise test parameters in jaundiced versus non-jaundiced patients demonstrates that obstructive jaundice does not impair cardiopulmonary exercise physiology. This further supports emerging evidence in contemporary literature that jaundiced patients can proceed directly to surgery without preoperative biliary drainage. The results of this study also show an interesting inverse relationship between body mass index and anaerobic threshold which is analysed in more detail in Chapter 4. Chapter 4 examines the relationship between preoperative cardiopulmonary exercise physiology and body composition in depth. All parameters measured at cardiopulmonary exercise test are compared against body composition and body mass index. The results of this chapter report that the current method of reporting V˙O2, both at peak exercise and anaerobic threshold, is biased against obese subjects and advises caution in the interpretation of cardiopulmonary exercise test results in patients with a high BMI. This is particularly important as current evidence in literature suggests that postoperative outcomes in obese subjects are comparable to non-obese subjects while cardiopulmonary exercise test results are also abnormally low in this very same cohort of patients. Chapter 5 analyses the relationship between preoperative clinico-pathological characteristics including systemic inflammation and the magnitude of the postoperative systemic inflammatory response. Obstructive jaundice appears to have an immunosuppressive effect while elevated preoperative CRP and hypoalbuminemia appear to have opposite effects with hypoalbuminemia resulting in a lower response while elevated CRP in the absence of hypoalbuminemia resulted in a greater postoperative systemic inflammatory response. Chapter 6 evaluates the role of the early postoperative systemic inflammatory response in predicting complications after pancreaticoduodenectomy and aims to establish clinically relevant thresholds for C-Reactive Protein for the prediction of complications. The results of this chapter demonstrate that CRP levels as early as the second postoperative day are associated with complications. While post-operative CRP was useful in the prediction of infective complications, this was the case only in patients who did not develop a post-operative pancreatic fistula. The predictive ability of inflammatory markers for infectious complications was blunted in patients with a pancreatic fistula. Chapter 7 summarises the findings of this thesis, their place in current literature and future directions. The results of this thesis add to the current knowledge regarding the complex pathophysiological abnormalities in patients undergoing pancreaticoduodenectomy, with specific emphasis on the interaction between cardiopulmonary exercise physiology, obstructive jaundice, systemic inflammation and postoperative outcomes. The work presented in this thesis lays the foundations for further studies aimed at improving outcomes after pancreaticoduodenectomy through the development of individualised, goal-directed therapies that are initiated well before this morbid yet necessary operation is performed.

Solid-liquid interactions in microscale structures and devices

Liquid-solid interactions become important as dimensions approach mciro/nano-scale. This dissertation focuses on liquid-solid interactions in two distinct applications: capillary driven self-assembly of thin foils into 3D structures, and droplet wetting of hydrophobic micropatterned surfaces. The phenomenon of self-assembly of complex structures is common in biological systems. Examples include self-assembly of proteins into macromolecular structures and self-assembly of lipid bilayer membranes. The principles governing this phenomenon have been applied to induce self-assembly of millimeter scale Si thin films into spherical and other 3D structures, which are then integrated into light-trapping photovoltaic (PV) devices. Motivated by this application, we present a generalized analytical study of the self-folding of thin plates into deterministic 3D shapes, through fluid-solid interactions, to be used as PV devices. This study consists of developing a model using beam theory, which incorporates the two competing components — a capillary force that promotes folding and the bending rigidity of the foil that resists folding into a 3D structure. Through an equivalence argument of thin foils of different geometry, an effective folding parameter, which uniquely characterizes the driving force for folding, has been identified. A criterion for spontaneous folding of an arbitrarily shaped 2D foil, based on the effective folding parameter, is thus established. Measurements from experiments using different materials and predictions from the model match well, validating the assumptions used in the analysis. As an alternative to the mechanics model approach, the minimization of the total free energy is employed to investigate the interactions between a fluid droplet and a flexible thin film. A 2D energy functional is proposed, comprising the surface energy of the fluid, bending energy of the thin film and gravitational energy of the fluid. Through simulations with Surface Evolver, the shapes of the droplet and the thin film at equilibrium are obtained. A critical thin film length necessary for complete enclosure of the fluid droplet, and hence successful self-assembly into a PV device, is determined and compared with the experimental results and mechanics model predictions. The results from the modeling and energy approaches and the experiments are all consistent. Superhydrophobic surfaces, which have unique properties including self-cleaning and water repelling are desired in many applications. One excellent example in nature is the lotus leaf. To fabricate these surfaces, well designed micro/nano- surface structures are often employed. In this research, we fabricate superhydrophobic micropatterned Polydimethylsiloxane (PDMS) surfaces composed of micropillars of various sizes and arrangements by means of soft lithography. Both anisotropic surfaces, consisting of parallel grooves and cylindrical pillars in rectangular lattices, and isotropic surfaces, consisting of cylindrical pillars in square and hexagonal lattices, are considered. A novel technique is proposed to image the contact line (CL) of the droplet on the hydrophobic surface. This technique provides a new approach to distinguish between partial and complete wetting. The contact area between droplet and microtextured surface is then measured for a droplet in the Cassie state, which is a state of partial wetting. The results show that although the droplet is in the Cassie state, the contact area does not necessarily follow Cassie model predictions. Moreover, the CL is not circular, and is affected by the micropatterns, in both isotropic and anisotropic cases. Thus, it is suggested that along with the contact angle — the typical parameter reported in literature quantifying wetting, the size and shape of the contact area should also be presented. This technique is employed to investigate the evolution of the CL on a hydrophobic micropatterned surface in the cases of: a single droplet impacting the micropatterned surface, two droplets coalescing on micropillars, and a receding droplet resting on the micropatterned surface. Another parameter which quantifies hydrophobicity is the contact angle hysteresis (CAH), which indicates the resistance of the surface to the sliding of a droplet with a given volume. The conventional methods of using advancing and receding angles or tilting stage to measure the resistance of the micropatterned surface are indirect, without mentioning the inaccuracy due to the discrete and stepwise motion of the CL on micropillars. A micronewton force sensor is utilized to directly measure the resisting force by dragging a droplet on a microtextured surface. Together with the proposed imaging technique, the evolution of the CL during sliding is also explored. It is found that, at the onset of sliding, the CL behaves as a linear elastic solid with a constant stiffness. Afterwards, the force first increases and then decreases and reaches a steady state, accompanied with periodic oscillations due to regular pinning and depinning of the CL. Both the maximum and steady state forces are primarily dependent on area fractions of the micropatterned surfaces in our experiment. The resisting force is found to be proportional to the number of pillars which pin the CL at the trailing edge, validating the assumption that the resistance mainly arises from the CL pinning at the trailing edge. In each pinning-and-depinning cycle during the steady state, the CL also shows linear elastic behavior but with a lower stiffness. The force variation and energy dissipation involved can also be determined. This novel method of measuring the resistance of the micropatterned surface elucidates the dependence on CL pinning and provides more insight into the mechanisms of CAH.

Degradation of compounds present in cork boiling water by gamma radiation

Cork boiling water is an aqueous and complex dark liquor with high concentration of phenolic compounds such as phenolic acids and tannins [1, 2], which are considered biorecalcitrants [2]. Ionizing radiation has been widely studied as an alternative technology for the degradation of organic contaminants without the addition of any other (e.g.: Fenton technologies). The aim of this work was to identify the compounds present in cork boiling water and further evaluate the resulting stable degradation products after gamma irradiation. The irradiation experiments of standard solutions were carried out at room temperature using a Co-60 experimental equipment. The applied absorbed doses were 20 and 50 kGy at a dose rate of 1.5 kGy/h, determined by routine dosimeters [3]. The identification of radiolytic products was carried out by HPLC-DAD-ESI/MS. The phenolic compounds were identified by comparing their retention times and UV–vis and mass spectra with those obtained from standard compounds, when available, as well as by comparing the obtained information with available data reported in the literature. Concerning the obtained results and the literature review, the main cork wastewater components are: quinic, gallic, protocatechuic, vanillic, syringic and ellagic acids. Based on this, we used protocatechuic, vanillic and syringic acids as model compounds to study their degradation by gamma radiation in order to identify the corresponding radiolytic products. Standard aqueous solutions were irradiated and the derivatives of each model compound are represented in figure 1. The obtained results seem to demonstrate that the derivatives of the parent compounds could also be phenolic acids, since it was observed the loss of 44 u (CO2) from the [M-H]- ions. Gallic and protocatechuic acids are identified as derivatives of vanillic and syringic acids, and gallic acid as a protocatechuic acid derivative. Compound 5 ([M-H]- at m/z 169) was tentatively identified as 2,4,6-trihydroxybenzoic acid, since its fragmentation pattern (m/z 151, 125 and 107) is similar to that previously reported in literature [4]. The structure of compound 7 was proposed based on the molecular ion and its fragmentation and compound 6 remains unknown.

Use of aromatic and medicinal plants, drugs and herbal products in Bragança city

Herbal therapy is characterized by the use of aromatic and medicinal plants (AMP) in different pharmaceutical forms for therapeutic purposes. The present study aims to characterize the use of AMP, drugs and herbal products in Bragança city. For this, a cross-sectional study was conducted through application of a questionnaire to 404 subjects of both gender and aged between 18 and 89 years. AMP were therapeutically used by 53.7% mainly due “to be natural” (43.9%) while 33.8% use drugs and/ or herbal products mainly “because it is good for health” (53.5%). The AMP most used were Cidreira (n=149) and Camomila (n=117) and concerning drugs and/ or herbal products Valdispert® (n=48) and Daflon® 500 (n=41) were the most reported. Overall, the reported uses of AMP, drugs and herbal products were correct, according to the reported in literature. The use of AMP is motivated by self-knowledge (55.4%) while drugs and/ or herbal products are used mostly by medical prescription (44.1%). AMP were obtained by own cultivation (44.1%) and drug and/ or herbal products in pharmacies (89.0%). Of all users, about 90% not combined these products with conventional drugs and it was identified just one potential occurrence of drug interactions related with the use of Hipericão. The occurrence of adverse effects was noted after the use of AMP Sene (11.8%), Hipericão (9.1%) and Ginkgo Biloba (8.3%). The use of these products is a common practice among the residents of Bragança city, which use a wide diversity of AMP and plant-based products.

Estimating mortality in laying hens as the environmental temperature increases

Layer mortality due to heat stress is an important economic loss for the producer. The aim of this study was to determine the mortality pattern of layers reared in the region of Bastos, SP, Brazil, according to external environment and bird age. Data mining technique were used based on monthly mortality records of hens in production, 135 poultry houses, from January 2004 to August 2008. The external environment was characterized according maximum and minimum temperatures, obtained monthly at the meteorological station CATI in the city of Tupa, SP, Brazil. Mortality was classified as normal (<= 1.2%) or high (> 1.2%), considering the mortality limits mentioned in literature. Data mining technique produced a decision tree with nine levels and 23 leaves, with 62.6% of overall accuracy. The hit rate for the High class was 64.1% and 59.9% for Normal class. The decision tree allowed finding a pattern in the mortality data, generating a model for estimating mortality based on the thermal environment and bird age.

Branch and Bound algorithms in greenhouse climate control

The horticultural sector has become an increasingly important sector of food production, for which greenhouse climate control plays a vital role in improving its sustainability. One of the methods to control the greenhouse climate is Model Predictive Control, which can be optimized through a branch and bound algorithm. The application of the algorithm in literature is examined and analyzed through small examples, and later extended to greenhouse climate simulation. A comparison is made of various alternative objective functions available in literature. Subsequently, a modidified version of the B&B algorithm is presented, which reduces the number of node evaluations required for optimization. Finally, three alternative algorithms are developed and compared to consider the optimization problem from a discrete to a continuous control space.

Seasonal concentration of cruise tourism in the Mediterranean

This research delves into analyzing the seasonality of cruise tourism in the Mediterranean by using the decomposition of the Gini index, used in the field of cruise tourism for the first time in literature. This study specifically used the decomposition to evaluate the contribution degree of each port to the global seasonal concentration of each Mediterranean region. Moreover, a cluster analysis technique (bootstrapped bagged clustering) was applied to classify the ports into homogeneous groups according to their seasonal patterns given the significant heterogeneity revealed in the major regions of the Mediterranean. The methodology applied can serve as a control and monitoring tool for measuring seasonal concentration levels in cruise tourism, allowing for policies against seasonality to be tailored in the cruise tourism segment.

UTILIZING ELECTRONIC NOSE AND GC-MS TO EXAMINE CRITICAL FACTORS INFLUENCING THE FORMATION OF ODOROUS VOC’S IN BIOSOLIDS.

Despite the efforts to better manage biosolids field application programs, biosolids managers still lack of efficient and reliable tools to apply large quantities of material while avoiding odor complaints. Objectives of this research were to determine the capabilities of an electronic nose in supporting process monitoring of biosolids production and, to compare odor characteristics of biosolids produced through thermal-hydrolysis anaerobic digestion (TH-AD) to those of alkaline stabilization in the plant, under storage and in the field. A method to quantify key odorants was developed and full scale sampling and laboratory simulations were performed. The portable electronic nose (PEN3) was tested for its capabilities of distinguishing alkali dosages in the biosolids production process. Frequency of recognition of unknown samples was tested achieving highest accuracy of 81.1%. This work exposed the need for a different and more sensitive electronic nose to assure its applicability at full scale for this process. GC-MS results were consistent with those reported in literature and helped to elucidate the behavior of the pattern recognition of the PEN3. Odor characterization of TH-AD and alkaline stabilized biosolids was achieved using olfactometry measurements and GC-MS. Dilution-to-threshold of TH-AD biosolids increased under storage conditions but no correlation was found with the target compounds. The presence of furan and three methylated homologues in TH-AD biosolids was reported for the first time proposing that these compounds are produced during thermal hydrolysis process however, additional research is needed to fully describe the formation of these compounds and the increase in odors. Alkaline stabilized biosolids reported similar odor concentration but did not increase and the ‘fishy’ odor from trimethylamine emissions resulted in more offensive and unpleasant odors when compared to TH-AD. Alkaline stabilized biosolids showed a spike in sulfur and trimethylamine after 3 days of field application when the alkali addition was not sufficient to meet regulatory standards. Concentrations of target compounds from field application of TH-AD biosolids gradually decreased to below the odor threshold after 3 days. This work increased the scientific understanding on odor characteristics and behavior of two types of biosolids and on the application of electronic noses to the environmental engineering field.

Robustness in facility location

Facility location concerns the placement of facilities, for various objectives, by use of mathematical models and solution procedures. Almost all facility location models that can be found in literature are based on minimizing costs or maximizing cover, to cover as much demand as possible. These models are quite efficient for finding an optimal location for a new facility for a particular data set, which is considered to be constant and known in advance. In a real world situation, input data like demand and travelling costs are not fixed, nor known in advance. This uncertainty and uncontrollability can lead to unacceptable losses or even bankruptcy. A way of dealing with these factors is robustness modelling. A robust facility location model aims to locate a facility that stays within predefined limits for all expectable circumstances as good as possible. The deviation robustness concept is used as basis to develop a new competitive deviation robustness model. The competition is modelled with a Huff based model, which calculates the market share of the new facility. Robustness in this model is defined as the ability of a facility location to capture a minimum market share, despite variations in demand. A test case is developed by which algorithms can be tested on their ability to solve robust facility location models. Four stochastic optimization algorithms are considered from which Simulated Annealing turned out to be the most appropriate. The test case is slightly modified for a competitive market situation. With the Simulated Annealing algorithm, the developed competitive deviation model is solved, for three considered norms of deviation. At the end, also a grid search is performed to illustrate the landscape of the objective function of the competitive deviation model. The model appears to be multimodal and seems to be challenging for further research.

Phyllodes tumor of the breast: a clinic-pathologic study of 77 cases in a Hispanic cohort

Introduction: Breast Phyllodes tumors are rare breast tumors present in less than 1% of new cases of breast cancer, usually occurring among middle-aged women (40-50 yrs). Objective: This study shows diagnostic experience, surgical management and follows up of patients with this disease during a period of ten years in a oncology referral center. Methods: Retrospectively, breast cancer registries at the institution were reviewed, identifying 77 patients with Phyllodes tumors between 2002 and 2012, who had been operated on at the Instituto de Cancerología – Clínica Las Américas, in Medellín (Colombia). Clinical and histopathological data belonging to these cases was captured and analyzed and descriptive statistics were used. Results: The follow up median was 22.5 months (IQR: 10.5-60.0), average age was 47.2 yrs (SD: 12.4), mean tumor size was 3.6 cm (SD: 4.6), 88.3% of the patients (68 cases) presented negative margins and none of them received adjuvant chemotherapy. Of the patients with Phyllodes tumors; 33.8% had benign, 31.2% had borderline and 35.0% had malignant tumor. Disease-free survival was 85.8% and overall survival was 94.5%. Discussion: Reported data in this article is in accordance with what has been reported in worldwide literature. In our cohort even the high mean size of the tumors, the risk of local relapse and metastatic disease is low than previously reported in literature. Trials with longer follow up and molecular trials in Phyllodes tumors are necessary to understand the behavior of these tumors in Hispanics population.

Mapping the Liminal Experience of Eastern Europe in Selected American Works, 1965-2002

The purpose of this dissertation is to study literary representations of Eastern Europe in the works of celebrated and less-known American authors, who visited and narrated the region between the mid-1960s and early 2000s. The main critical body focuses on Eastern Europe before 1989 and encompasses three major voices of American literature: John Updike, Joyce Carol Oates, and Philip Roth. However, in the last chapter I also explore American literary perceptions of the area following the collapse of communism. Importantly, the term “Eastern Europe” as used in this dissertation is charged with significance. I approach it not only as a space on the map or the geopolitical construct which emerged in the aftermath of the Second World War, but rather as a conceptual category and a repository of meanings built out of fact and fantasy: specific historical, political and cultural realities interlaced with subjective worldviews, preconceptions, and mental images. The critical framework of this dissertation is twofold. I reach for the concept of liminality to elucidate the indeterminacy and malleability which lies at the heart of the object of study—the idea, image, and experience of Eastern Europe. Bearing in mind the nature of the works under analysis, all of which were inspired by actual visits behind the Iron Curtain, I propose to interpret these transatlantic literary journeys in terms of generative experience, where Eastern Europe is mapped as a liminal space of possibility; a contact zone between cultures and, potentially, the locus of self-discovery and individual transformation. If liminality is the metaphor or a lens that I employ in order to account for the nature of the analyzed works and the complex terrain they map, imagology, whose purpose is to study the processes of constructing selfhood and otherness in literature, provides me with the method and the critical vocabulary for analyzing selected literary representations. The dissertation is divided into six chapters, the last of which serves as coda to the previous discussion. The first two chapters constitute the critical foundation of this work. Then, in chapters 3, 4, and 5 I study American images of Eastern Europe in the works written by John Updike, Joyce Carol Oates, and Philip Roth, respectively. The last, sixth chapter of this dissertation is divided into two parts. In the first one, I discuss new critical perspectives and avenues of research in the study of Eastern Europe following the collapse of communism. Then, I carry out a joint analysis of four works written after 1989 by Eva Hoffman, Arthur Phillips, John Beckman, and Gary Shteyngart. The dissertation ends with conclusions in which I summarize my findings and reflections, and suggest implications for future research. As this dissertation seeks to demonstrate, Eastern Europe portrayed in the analyzed works oscillates between contradictory representations which are contingent upon a number of factors, most importantly who maps it and in what context. Even though each experience of Eastern Europe is distinct and fueled by the profiles, identities, and interests of the characters and their creators, I have found out that certain patterns of othering are present in all the works. Thus, my research seems to suggest that there is something of a recurrent literary image of Eastern Europe, which goes beyond the context of the Cold War. Accordingly, while this dissertation hopes to be a valid contribution to the study of literary and cultural mappings of Eastern Europe, it also generates new questions regarding the current, post-communist representation of the area and its relationship to the national tropes explored in my work.