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Evolution
Published in Paul Pumpens, Single-Stranded RNA Phages, 2020
The 40 years of Spiegelman's team's experiments and of the in vitro evolution were celebrated by the circumstantial review that was written by Gerald F. Joyce (2007) and dedicated to Leslie Orgel on the occasion of his 80th birthday. Figure 18.4 presents the cover of the review in question. The review carefully summarized the concepts and methods for the directed evolution of the RNA molecules in vitro. Moreover, Joyce emphasized that the in vitro evolution established the Darwinian evolution as a chemical process for the first time, and paved the way for the many directed evolution experiments that followed.
Habitat imaging of tumor evolution by magnetic resonance imaging (MRI)
Published in Ruijiang Li, Lei Xing, Sandy Napel, Daniel L. Rubin, Radiomics and Radiogenomics, 2019
Bruna Victorasso Jardim-Perassi, Gary Martinez, Robert Gillies
The advantage of HI is that it may have the capability to distinguish the aforementioned subtle differences because multiple independent MRI parameters are simultaneously used, whereas a single parameter, such as ADC or T2, may be insufficient. In addition, HI can cast these differences within a framework of Darwinian evolution. Therefore, HI has two essential components: (1) it requires that some form of classification or segmentation of regions, based on mpMRI data, be performed and (2) that these regions be relatable to tumor physiological habitats. Without (2), this would simply be mpMRI. Without (1), (2) may not be possible.
SBA Answers and Explanations
Published in Vivian A. Elwell, Jonathan M. Fishman, Rajat Chowdhury, SBAs for the MRCS Part A, 2018
Vivian A. Elwell, Jonathan M. Fishman, Rajat Chowdhury
It is very important to recognize that the clinical phase of a tumour – that is, the time from it becoming clinically apparent until it causes the death of the patient (assuming no treatment) – is short in comparison to the preclinical phase. Thus, by the time a solid tumour is detected, it has already completed a major portion of its life cycle. During the long preclinical phase there is time for invasion and metastasis to occur. In addition, there is time for cell heterogeneity to develop within the tumour. This means that over and above the initial mutations, further genetic events occur in sub-populations of the tumour, leading to variation and the outgrowth of sub-populations with different patterns of differentiation and properties (a form of Darwinian evolution).
Apophenic Reading and the Politics of Psychoanalysis
Published in Studies in Gender and Sexuality, 2022
Freud’s theory of the unconscious demotes the ego from the position of “master of its own house” (Freud, 1917, p. 142). Since it is inherently inaccessible and unknowable, the unconscious is, profoundly, an alien impulse at the very heart of what we think of as our “human” selves. Freud declares that psychoanalysis is the third of “three severe blows” to human exceptionalism and the “universal narcissism of men” (1917, p. 138). The first is the Copernican revolution, which decentered Earth from the center of the universe; the second is Darwinian evolution, which placed the human in direct genealogical relation to other animals and life on earth. The third psychoanalytic blow to human exceptionalism is the unconscious: We are not in full control or possession of our own minds; there are covert processes that structure being and behavior. Pellegrini writes that this may be a reading of psychoanalysis that “chastens [human] fantasies of mastery (Singh, 2017) and welcomes the dis-ease of the unheimlich, the unhomely home (Freud, 1917, p. 142; see also Freud, 1919). Nevertheless, the force of anthropo-centrism and the will to reduce and master the disturbance of the alien return again and again in Freud’s body of work” (Pellegrini, 2018, p. 15). Freud himself, in writing psychoanalysis, is “not of one mind”: He vacillates between human exceptionalism and humility, self-possession and dispossession (p. 16).
Multi-objective optimization methods in novel drug design
Published in Expert Opinion on Drug Discovery, 2021
George Lambrinidis, Anna Tsantili-Kakoulidou
Evolutionary algorithms (EAs) have been developed as effective methods for exploring high dimensionality and are successfully applied to a variety of multi-objective optimization problems [30]. In drug design, genetic algorithms (GA) are the most popular and well-known class of evolutionary algorithms, while evolutionary programming (EP) and evolution strategies (ES) are the two other broad classes [40,41]. As the name suggests GAs or EAs are inspired by the mechanisms of evolution followed in nature; in other words, they are the computer equivalent of Darwinian evolution. GAs apply genetic operators, like crossover and mutation, to generate potential solutions for a high dimensional problem, represented by a population of chromosomes. The ‘goodness’ of each solution is evaluated by a score of fitness, according to a fitness function or using Pareto analysis. GAs find applications in many drug research areas from conformation search and molecular docking to combinatorial library construction and de novo drug design to create new molecules [42,43], while they can be combined with regression and/or classification as well as machine learning techniques to support QSAR in descriptors selection and in the construction of models for biological properties prediction [44,45].
Tumor heterogeneity: does it matter?
Published in Expert Review of Anticancer Therapy, 2019
Casmir Turnquist, Robert A Watson, Andrew Protheroe, Clare Verrill, Shivan Sivakumar
The two main models explaining how heterogeneity arises are the stochastic or clonal evolution model and the cancer stem cell (CSC) model (Figure 2) [3]. The stochastic model proposed by Peter Nowell in 1976 [4] states that tumors arise from a single mutated cell, which acquires additional mutations over time. Each of these individual mutations gives rise to subpopulations of tumor cells. According to basic principles of Darwinian evolution, these subpopulations may possess survival advantages and become dominant owing to different capacities for proliferation, invasion, and migration. The clones that possess an advantage expand, while the clones with less fitness become extinct. Importantly, tumor microenvironment may differ in space and time. For instance, in regions of relative hypoxia, clones that are suited to survive under these environmental conditions thrive. Together, these factors create heterogeneity spatially and temporally.