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Nanoscale measurement of water diffusion on a topological insulator: The origin of correlated motion and friction
No full textThe microscopic motion of water is a central question,
but gaining experimental information about the interfacial
dynamics of water for instance in catalysis, biophysics
and nanotribology is extremely challenging due
to its ultrafast dynamics, and the complex interplay of
intermolecular and molecule-surface interactions. Here
we present the first experimental and computational
study of the nanoscale-nanosecond motion of water at
the surface of a topological insulator (TI, Bi2Te3). In
addition to the technological relevance and scientific interest
on the interfacial behaviour of water, understanding
the interaction of TI surfaces with molecules is a
key to design and manufacturing for future applications.
However the surface chemistry of these materials has
hitherto been hardly addressed and exploratory work
on the motion of molecules on TI surfaces has been so
far solely based on computational studies.
By analysing the scattering lineshape from helium spinecho
spectroscopy and comparing the results with van
der Waals-corrected density functional theory calculations
we are able to obtain a general insight into the
diffusion and mobility of water on a topological insulator
surface. Instead of the expected Brownian motion,
we find strong evidence of a complex diffusion mechanism
which follows an activated hopping motion on a
corrugated potential energy surface and shows signatures
of correlated motion with unusual repulsive interactions
between the individual water molecules. From
the experimental lineshape broadening we determine
the diffusion coefficient, the diffusion energy and the
pre-exponential factor
Uncertainties in focused ion beam characterisation
No full textFocused ion beam (FIB) and dual-beam microscopy is a common tool used for materials characterisation, including 3D cross-sectional imaging and micro-mechanical analysis.
These techniques have enabled new and revolutionary insight into the behaviour of materials at the microscale, however relating these properties to the bulk material to produce useful quantitative data is more challenging. With a wide range of instruments and setups available, as well as user variability, it is very difficult to control consistency and quality of FIB acquired data.
This project examines some of the artefacts produced in materials by the act of characterisation with focused ion beam, causing uncertainties and errors in the acquired data and subsequent measurements on the dataset. Fundamental experiments on silicon-based samples are done initially because it is a well-characterised and simple material, which behaves predictably with FIB milling. Tungsten carbide cobalt (WC/Co) hardmetals are then studied because they are sensitive to FIB milling, undergoing microstructural changes and having a very slow milling rate, making them a good study material.
The artefacts investigated are: the variation in slice thickness during serial sectioning for 3D reconstruction, phase transformation in the sample material, and non-perfect geometries and ion-induced damage in micro-mechanical test specimens, specifically micropillars.
The experiments carried out demonstrate the severity of each artefact and develop possible prevention methods and improvements to the methods.
Slice thickness variation in serial sectioning cannot be directly prevented as it is inherent to the instrument. However, by including a measurement device with known geometry in the acquisition of the data, the slices can be measured during data processing and the values appropriately adjusted in volume reconstructions. The development of the invention and analysis processes of such a device is described. In an attempt to standardise
slice thickness measurement, a possible solution for mass production of the devices is also discussed.
Phase transformation during milling causes uncertainty in microstructural characterisation of a susceptible material, due to the induced phase disguising the existing phase composition of the material. FIB milling does not affect all materials in this way, but one
of the most severe occurrences is in cobalt and the cobalt binder phase in WC/Co hardmetals.
The underlying mechanism of the transformation is explored and the preparation conditions that avoid it are identified.
Micro-mechanical testing is a newer implemented capability of FIB microscopy, and one
of the most commonly tested geometries is micro-pillars for compression testing. Due
to the shape and damaging nature of the beam, uncertainties associated with reproducibility
of micro-pillar specimens and induced changes in the material can affect the mechanical properties of the material being tested. This has significant ramifications on the reliability and validity of quantitative measurements made on micro-pillars, especially when comparing with bulk material properties. A few experiments are described that investigate different aspects of micro-pillar experiments, including a focus on metrology (using silicon), feasibility when applied to a complex composite material (WC/Co), and practical and interesting aspects when applied to a single crystal material (WC)
In pursuit of causality in leadership training research: A review and pragmatic recommendations
No full textAlthough research shows a reliable association between leadership training and positive organizational outcomes, a range of research design issues mean we do not know to what degree the former causes the later. Accordingly, the paper has two main aims. First, to describe the conditions necessary to determine causality in leadership training research and the ability of different research designs to achieve this. Six important, but often ignored, issues associated with determining causality are described (control conditions, sample representation, condition randomization, condition independence, temporal design, and author involvement). Second, to review the extent to which the leadership training literature is able to demonstrate causality. The review shows that the majority of studies do not meet many of the criteria, even the most basic criteria, required to establish causality. Finally, we provide guidelines for designing future research to improve causal identification and is capable of generating meaningful theory and policy recommendations.
“Shallow men believe in luck. Strong men believe in cause and effect”
(Ralph Waldo Emerson)</p
Improving Productivity in Hollywood with Data Science: Using Emotional Arcs of Movies to Drive Product and Service Innovation in Entertainment Industries.
No full textImproving productivity in the entertainment industry is a very challenging task as it heavily depends on generating attractive content for the consumers. The consumer-centric design (putting the consumers at the centre of the content development and production) focuses on ways in which businesses can design customized services and products which accurately reflect consumer preferences. We propose a new framework which allows to use data science to optimize content-generation in entertainment and test this framework for the motion picture industry. We use the natural language processing methodology combined with econometric analysis to explore whether and to what extent emotions shape consumer preferences for media and entertainment content, which, in turn, affect revenue streams. By analyzing 6,174 movie scripts, we generate the emotional trajectory of each motion picture. We then combine the obtained mappings into clusters which represent groupings of consumer emotional journeys. These clusters are then plugged into an econometric model to predict overall success parameters of the movies including box office revenues, viewer satisfaction levels (captured by IMDb ratings), awards, as well as the number of viewers’ and critics’ reviews. We find that emotional arcs in movies can be partitioned into 6 basic shapes. The highest box offices are associated with the Man in a Hole shape which is characterized by an emotional fall followed by an emotional rise. This U-shaped emotional arc results in financially successful movies irrespective of genre and production budget. Implications of this analysis for generating on-demand content and improving productivity in entertainment industries are discussed
Effect of surface tension on the behavior of adhesive contact based on Maugis‒Dugdale model.
No full textThis present study reconsiders the effect of surface tension on the behavior of adhesive contact between a rigid sphere and an elastic half-plane, in which the adhesive interactions are supposed to follow the Dugdale laws. The adhesive contact issue is transformed into two inter coupled non-linear integral equations which are governed by two parameters: λ (Maugis adhesion parameter) and S (elastocapillary number). By means of iteration method, numeric results are obtained. Analogous to the traditional Maugis-Dugdale (M-D) model, the results provide transition of the pull-off force between JKR and DMT type contact models through the Maugis adhesion parameter λ with a fixed parameter S. On the other hand, with a fixed adhesion parameter λ, we also present the transitions of the pull-off force between four extreme models, named M-D, JKR, Bradley models and Young–Dupre equation, through adjustment of the parameter S. Finally, we find the uniformity and discontinuity of the pressure distribution are affected by the combination of three factors: applied load P, adhesion parameter λ and elastocapillary number S
Motor skills predict faux pas understanding in middle childhood
No full textThis study examined emotion understanding (as assessed by the Test of Emotion Comprehension; Pons, Harris, & DeRosnay, 2004) and motor skills (as assessed by the Movement Assessment Battery for Children; Henderson, Barnett, & Sudgen, 2007) as predictors of children’s understanding of faux pas (Banerjee, Watling, & Caputi, 2011). Faux paus situations are those in which someone causes unintentional offence or behaves inappropriately. Understanding of faux pas requires knowledge of social norms in specific situations as well as emotion understanding. Misunderstanding faux pas can prevent smooth social functioning. Fifty-six children (aged 7;0 to 9;11 years) completed a measure of faux pas understanding, emotion understanding, and motor skills. Children’s faux pas understanding, emotion understanding, and motor skills were all related to each other. However, when age, motor skills, and emotion understanding were entered into a regression to predict faux pas understanding, only motor skills predicted understanding of faux pas. The findings are discussed in relation to potential pathways between motor skills and social understanding
Fully Degradable Thioester-functional Homo- and Alternating Copolymers Prepared through Thiocarbonyl Addition–Ring-opening RAFT Radical Polymerization
No full textThe radical ring-opening polymerization (RROP) of thionolactones provides access to thioester backbone-functional copolymers but has, to date, only been demonstrated on acrylic copolymers. Herein, the thionolactone dibenzo[c,e]oxepane-5-thione (DOT) was subjected to azobisisobutyronitrile (AIBN)-initiated free-radical homopolymerization, which produced a thioester-functional homopolymer with a glass-transition temperature of 95 °C and the ability to degrade exclusively into predetermined small molecules. However, the homopolymerization was impractically slow and precluded the introduction of functionality. Conversely, the reversible addition–fragmentation chain-transfer (RAFT)-mediated copolymerization of DOT with N-methylmaleimide (MeMI), N-phenylmaleimide (PhMI), and N-2,3,4,5,6-pentafluorophenylmaleimide (PFPMI) rapidly produced well-defined copolymers with the tendency to form alternating sequences increasing in the order MeMI ≪ PhMI < PFPMI, with estimated reactivity ratios of rDOT = 0.198 and rPFPMI = 0.0078 for the latter system. Interestingly, defects in the alternating structure were more likely caused by (degradable) DOT–DOT sequences rather than (nondegradable) MI–MI sequences, which was confirmed through the paper spray mass spectrometric analysis of the products from aminolytic degradation. Upon the aminolysis of backbone thioesters, maleimide repeating units were ring-opened, forming bisamide structures. Conversely, copolymer degradation through a thiolate did not result in imide substitution but nucleophilic para-fluoro substitution on PFPMI comonomer units, indicating the ability of DOT–MI copolymers to degrade under different conditions and to form differently functional products. The RROP of thionolactones has distinct advantages over the RROP of cyclic ketene acetals and is anticipated to find use in the development of well-defined degradable polymer materials
Information Theory and Medical Decision Making
No full textInformation theory has gained application in a wide range of disciplines,
including statistical inference, natural language processing, cryptography and
molecular biology. However, its usage is less pronounced in medical science. In this
chapter, we illustrate a number of approaches that have been taken to applying
concepts from information theory to enhance medical decision making. We start
with an introduction to information theory itself, and the foundational concepts of
information content and entropy. We then illustrate how relative entropy can be used
to identify the most informative test at a particular stage in a diagnosis. In the case
of a binary outcome from a test, Shannon entropy can be used to identify the range
of values of test results over which that test provides useful information about the
patient’s state. This, of course, is not the only method that is available, but it can
provide an easily interpretable visualization. The chapter then moves on to introduce
the more advanced concepts of conditional entropy and mutual information and
shows how these can be used to prioritise and identify redundancies in clinical tests.
Finally, we discuss the experience gained so far and conclude that there is value in
providing an informed foundation for the broad application of information theory to
medical decision making
How do examiners mark? An investigation of marking processes used in the assessment of extended written responses
No full textExamination marking is a cognitively demanding task. In England, examiners of formal, high stakes assessments are tasked with marking hundreds of scripts accurately and consistently within a short, intensive period of time. Despite assessment and marking practices having been the focus of research for many years, there is comparatively little research into the judgement and decision making processes used by examiners when marking high stakes examinations. This thesis adopted a cognitive psychological perspective to investigate the cognitive marking strategies used when marking A-level Psychology responses, with a focus on the marking of extended written responses which have been consistently shown to be the least reliably marked. The thesis consists of five empirical studies. In Study 1, a hybrid thematic analysis of interviews with senior A-level Psychology examiners (n = 5) identified that the cognitive marking strategies used when marking extended written responses were qualitatively different to those previously identified in the marking of GCSE responses. Study 2, a multi-methods study confirmed these findings in a larger sample comprised of novice (n = 30) and experienced (n = 13) markers. The participants completed a marking activity whilst ‘thinking aloud’ followed by an online questionnaire which asked them about their marking practices. Qualitative and quantitative analyses identified that there were few differences in the marking strategies used by novice and experienced markers and that marking accuracy was not associated with marking strategy usage. A model of marking was developed which was investigated further in the subsequent studies. The next two studies investigated marking processes across a three week operational examining period. In Study 3, A-level Psychology examiners (n = 53) completed online surveys which asked them about their marking at four times points across the marking period. Statistical analysis identified that whilst there was an increase in marking speed, this was not the result of a reduction in how thoroughly responses were read, but rather the result of a decreased reliance on the physical mark scheme and less re-reading of material. Interestingly few differences were identified in the marking strategies of accurate and inaccurate examiners, although marking accuracy was found to be associated with the use of an internalised marking schema. Further insight into the model of marking was gained from Study 4, in which a small sample (n = 5) of the Study 3 examiners completed a marking activity whilst having their eye-movements tracked, once at the start of the examining period and again at the end. A semi-structured interview followed the marking activity and included a cued retrospective think aloud (RTA) generated from the examiners watching a replay of their eye movements. Qualitative analysis of the data led to a revised model of marking. In Study 5, aspects of the model were validated using secondary marking accuracy data obtained from the examiners used in Study 3 (n = 53) and the associated population of A-level Psychology examiners (N = 284). The thesis concludes that marking takes place within an individual mental marking paradigm (MeMaP), the values of which are resistant to change. This suggests that ensuring examiners develop and embed a shared understanding of the mark scheme is crucial to marking accuracy
Patterns of symptoms possibly indicative of cancer and associated help-seeking behaviour in a large sample of United Kingdom residents - the USEFUL study
No full textBackground. Cancer awareness campaigns aim to increase awareness of the potential seriousness of signs and symptoms of cancer, and encourage their timely presentation to healthcare services. Enhanced understanding of the prevalence of symptoms possibly indicative of cancer in different population subgroups, and associated general practitioner (GP) help-seeking behaviour, will help to target cancer awareness campaigns more effectively.
Aim. To determine: i) the prevalence of 21 symptoms possibly indicative of breast, colorectal, lung or upper gastrointestinal cancer in the United Kingdom (UK), including six ‘red flag’ symptoms; ii) whether the prevalence varies among population subgroups; iii) the proportion of symptoms self-reported as presented to GPs; iv) whether GP help-seeking behaviour varies within population subgroups.
Methods. Self-completed questionnaire about experience of, and response to, 25 symptoms (including 21 possibly indicative of the four cancers of interest) in the previous month and year; sent to 50,000 adults aged 50 years or more and registered with 21 general practices in Staffordshire, England or across Scotland.
Results. Completed questionnaires were received from 16,778 respondents (corrected response rate 34.2%). Almost half (45.8%) of respondents had experienced at least one symptom possibly indicative of cancer in the last month, and 58.5% in the last year. The prevalence of individual symptoms varied widely (e.g. in the last year between near zero% (vomiting up blood) and 15.0% (tired all the time). Red flag symptoms were uncommon. Female gender, inability to work because of illness, smoking, a history of a specified medical diagnosis, low social support and lower household income were consistently associated with experiencing at least one symptom possibly indicative of cancer in both the last month and year. The proportion of people who had contacted their GP about a symptom experienced in the last month varied between 8.1% (persistent cough) and 39.9% (unexplained weight loss); in the last year between 32.8% (hoarseness) and 85.4% (lump in breast). Nearly half of respondents experiencing at least one red flag symptom in the last year did not contact their GP about it. Females, those aged 80+ years, those unable to work because of illness, ex-smokers and those previously diagnosed with a specified condition were more likely to report a symptom possibly indicative of cancer to their GP; and those on high household income less likely.
Conclusion. Symptoms possibly indicative of cancer are common among adults aged 50+ years in the UK, although they are not evenly distributed. Help-seeking responses to different symptoms also vary. Our results suggest important opportunities to provide more nuanced messaging and targeting of symptom-based cancer awareness campaigns
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