1,721,209 research outputs found
Development of a light driven biohybrid microbot
No full textEscherichia coli (E. coli) is a Gram-negative, rod-shaped bacterium that is
commonly found in the lower intestine of warm-blooded organisms. Its presence
is crucial for human health as it aids in the absorption of nutrients. Growing in
aerobic and anaerobic environments, it is highly adaptable and a versatile model
organism for different scientific studies.
E. coli has been extensively studied in molecular biology, genetics, and biotech-
nology due to its relatively simple genome, rapid growth rate, and the ease with
which it can be manipulated genetically. It was one of the first organisms to have
its genome sequenced, and this accomplishment has paved the way for numerous
advances in genetic engineering and synthetic biology. The bacterium’s ability to
express foreign genes has been harnessed to produce proteins, enzymes, and other
biological compounds. An example of this is being used for the production of insulin
and bringing down its cost by a huge factor.
In a way, it acts like a biological circuit board, where one can hack into its
programming and modifying its properties and behaviour. This also makes it a good
candidate to study physical phenomena.
This thesis explores the development, optimization, and applications of microbots
that are powered and controlled by such genetically modified E. coli bacteria. The
important gene modification we do makes the bacteria sensitive to green light, and
through this we can gain control over its speed. By integrating biological elements
with micro-robotics we investigate different complex phenomena. The research is
divided into two main parts: the theoretical foundations and practical applications
of microbots, and the methodologies for their fabrication and use in bacterial baths.
The first part of this thesis is regarding the microbot. In the first chapter, we get
an introduction to the E. coli bacteria, the hydrodynamics of flagellar motion, the
gene modification done to make these bacteria and the study of proteorhodopsin, the
bacterial light switch. We take an overview of the current trends and principles of
microbotics as well as scaling laws of the physical forces on a micron scale and their
limitations, framing key research questions guiding this study. The second chapter,
focuses on the development and optimization of the microbot design, including the
two-photon fabrication parameters and calibration of bacterial chambers. We take a
look at the measurement of drag coefficients and the effects of connector length on a
two-propeller design.
In chapter 3, we briefly describe the methods used in our studies and present
results about the microbot behaviour under uniform illumination and dynamic
feedback conditions. We discuss the Development of tracking and control algorithms
to enhance microbot efficiency. Chapter 4 focuses applications of microbots for
transporting cargo beads within microfluidic environments and to study geometric
optics approximation in self-propelled particles. This chapter also has sections on
other projects that have been carried out in the duration of this thesis. These
include the investigation of using 3D microstructures, including active pressure
around curved boundaries and torque measurement with light mills.
Part 2 of this thesis focuses on the methodologies used in the development of
microbots. Chapter 5 is focuses on the two-photon polymerization. This is a versatile
tool that can be used in rapid prototype development of 3D structures in micron
and sub-micron scale. We also go through the protocols for sample preparation and
microbot post-processing that were developed in the course of this study. Chapter 6
explains the techniques used for bacterial cell culture and investigation of bacterial
speed using differential dynamic microscopy.
In the course of this thesis, I developed a unique micro-robotic system that
integrates bacteria into synthetic 3D microstructures to extract mechanical work. I
designed and 3D fabricated the synthetic chassis using the two photon polymerization
process, calibrated it for the bacterial cells, developed coating protocols to reduce
surface interactions and develop a code to analyze and control the trajectories
of multiple microbots continuously captured through the microscope.This system
can control individual microbots autonomously and required a multi-disciplinary
approach, from research topics in physics, microbiology, synthetic biology, material
sciences, robotics and control theory and computer science. This system can find
applications in different fields of study
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
AI, Neuroscience and Aging
No full text<p>The booklet collects the contribution of the bilateral workshop on <em>Artificial Intelligence applied to neurosciences: applications of new technologies in Italy and Sweden</em></p>\n\n<p>Co-organized by the Scientific Office of the Embassy of Italy, the Karolinksa Institute and the University of Gothenburg, the ”AI, Neuroscience and Aging Symposium” was held in Stockholm on 27 and 28 November 2023.</p>\n\n<p>The aim of this symposium was to bring together Swedish and Italian researchers engaged in neuroscience research, encouraging a dynamic exchange of pioneering ideas thanks to new technologies based on the use of artificial intelligence and to promote interdisciplinary bilateral collaboration.</p>\n\n<p>The objective was to explore new opportunities to leverage artificial intelligence to deepen our understanding of neural mechanisms, while trying to explore new applications in cognitive functions and healthcare.</p>\n\n<p>The event provided an opportunity to create a lasting partnership and identify possibilities for competitive joint research initiatives to improve the understanding of intelligence, both human and artificial.</p>\n\n<p>The work of this bilateral meeting was coordinated by Augusto Marcelli, scientific attaché in Stockholm, JoanaB. Pereira, associate professor of the Karolinska Institute, and Giovanni Volpe, professor at the University of Gothenburg. </p>\n\n<p>The public event hosted at the Karolinska Institute.was attended by 200 researchers and students. There were contributions from Swedish and Italian Universities as well as two swedish companies: Sectra and Mabel AI.</p>
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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