Understanding Zipf's law of word frequencies through sample-space collapse in sentence formation

The formation of sentences is a highly structured and history-dependent process. The probability of using a specific word in a sentence strongly depends on the ‘history’ of word usage earlier in that sentence. We study a simple history-dependent model of text generation assuming that the sample-space of word usage reduces along sentence formation, on average. We first show that the model explains the approximate Zipf law found in word frequencies as a direct consequence of sample-space reduction. We then empirically quantify the amount of sample-space reduction in the sentences of 10 famous English books, by analysis of corresponding word-transition tables that capture which words can follow any given word in a text. We find a highly nested structure in these transition tables and show that this ‘nestedness’ is tightly related to the power law exponents of the observed word frequency distributions. With the proposed model, it is possible to understand that the nestedness of a text can be the origin of the actual scaling exponent and that deviations from the exact Zipf law can be understood by variations of the degree of nestedness on a book-by-book basis. On a theoretical level, we are able to show that in the case of weak nesting, Zipf''s law breaks down in a fast transition. Unlike previous attempts to understand Zipf''s law in language the sample-space reducing model is not based on assumptions of multiplicative, preferential or self-organized critical mechanisms behind language formation, but simply uses the empirically quantifiable parameter ‘nestedness’ to understand the statistics of word frequencies.     

Three-dimensional mapping of the light intensity transmitted through nanoapertures

A general method to map the 3D spatial distribution of light emerging from nanoscale apertures is presented that uses photolithographic techniques to create polymer replicas of the intensity distribution. The resulting features varied with aperture diameter and exposure time and showed good correlation with theory. This method provides direct visualization of the intensity distribution in close proximity to nanostructures and overcomes limitations imposed by physical probes where the contribution of the probe to the map requires deconvolution.     

A theoretical study of steady-state wedge cutting through metal plates

The process of steady-state wedge cutting through steel plates is investigated by analyzing experimental data and developing a simple and realistic model of the problem. Kinematics of the cutting process is discussed and three characteristic deformation zones are identified: (i) plastic zone at wedge tip, (ii) transient bent flap, and (iii) transition zone. Deformation energies are calculated for each zone, and the upper bound theorem in plasticity is applied to derive a closed-form solution for the cutting force. Frictional effects were considered including machining friction near the wedge tip and sliding friction between the transient flap and the wedge surface. Prediction of the steady-state cutting model is compared with experiments conducted at Cambridge University, MIT, and Det norske Veritas. Good correlation with the test data is reported. A parametric study is performed and on that basis a simple approximate solution is developed. An interesting association was discovered with previous empirical formulas proposed by Minorsky, Vaughan, and Kuroiwa.     

Identifying emerging failure phenomena in complex systems through engineering data mapping

In the past, standard reliability and risk approaches have sufficed to identify the dominant causes of failure in forensic analyses, and the dominant risk contributors for proactive risk investigations. These techniques are particularly applicable when individual or even simple common failure events of a similar type dominate the analysis. However, nowadays due to increased understanding of the ‘simple’ mechanisms and the increasing complexity of the systems we build, failures in highly dependable systems arise from unexpected interactions between subsystems and the external and internal environment.

Engineering data analysis is the process of data collection and investigation from a variety of perspectives, alternatively dissecting it into its underlying (yet often unknown) patterns; this process is becoming ever more necessary as systems become more complex. Some of the techniques employed are slicing the data sets according to known underlying variables, or overlaying data gathered from different perspectives, or imbedding data into previously established logical or phenomenological structures.

This paper addresses the issues involved in visualizing patterns in data sets by providing examples of interesting maps from the past, indicating some of the maps currently in use, and speculating on how these visual maps might be developed further and used in the future to discover problems in complex systems before they lead to failure. Guidance is proposed as to how to explore and map data from different technical perspectives in order to evoke potentially significant patterns from reliability data. The techniques presented have been developed by combining approaches to common cause failure (CCF) classification with multidimensional scaling (MDS) to produce a new method for exploratory engineering data mapping.     

Blood flow through arteries in a pathological state: A theoretical study

The aim of this paper is to develop a mathematical model for studying the non-Newtonian flow of blood through a stenosed arterial segment. Herschel-Bulkley equation has been taken to represent the non-Newtonian character of blood. The problem is investigated by a combined use of analytical and numerical techniques. It is noticed that the resistance of flow and the skin-friction increase as the stenosis height increases. The results are compared with data available in the existing literature presented by previous researchers.     

Land use, water and Mediterranean landscapes: modelling long-term dynamics of complex socio-ecological systems

The evolution of Mediterranean landscapes during the Holocene has been increasingly governed by the complex interactions of water and human land use. Different land-use practices change the amount of water flowing across the surface and infiltrating the soil, and change water's ability to move surface sediments. Conversely, water amplifies the impacts of human land use and extends the ecological footprint of human activities far beyond the borders of towns and fields. Advances in computational modelling offer new tools to study the complex feedbacks between land use, land cover, topography and surface water. The Mediterranean Landscape Dynamics project (MedLand) is building a modelling laboratory where experiments can be carried out on the long-term impacts of agropastoral land use, and whose results can be tested against the archaeological record. These computational experiments are providing new insights into the socio-ecological consequences of human decisions at varying temporal and spatial scales.     

A cross-sector review on the use of value stream mapping

Value Stream Mapping (VSM) has become a popular method for lean thinking and implementation in recent years. Previous reviews related to VSM are limited to individual sectors due to varied research objectives. The lack of studies which focus on cross-sector review of VSM studies is impeding the implementation of VSM by both lean researchers and practitioners. The paper aims to determine the-state-of-the-art development of VSM in five sectors, including manufacturing, health care, construction, product development and service sectors. A total of 131 journal articles are reviewed and analysed from the period of 1999–12/2016. The analysis covers the complete implementation cycle of VSM, including metrics for current state map, improvement techniques for future state map, benefits and achievements of VSM application, and critical success factors for VSM implementation. Cross-sector comparisons and investigations are conducted to understand the differences of VSM implementations in various sectors to facilitate VSM development and increase the number of successful VSM implementation. The results suggest that understanding value and waste in a diverse value stream environment and ensuring the suitability and usability of traditional lean metrics/techniques within the different flow settings are central to the VSM development.     

Recent advances in mapping environmental microbial metabolisms through 13C isotopic fingerprints

After feeding microbes with a defined ¹³C substrate, unique isotopic patterns (isotopic fingerprints) can be formed in their metabolic products. Such labelling information not only can provide novel insights into functional pathways but also can determine absolute carbon fluxes through the metabolic network via metabolic modelling approaches. This technique has been used for finding pathways that may have been mis-annotated in the past, elucidating new enzyme functions, and investigating cell metabolisms in microbial communities. In this review paper, we summarize the applications of ¹³C approaches to analyse novel cell metabolisms for the past 3 years. The isotopic fingerprints (defined as unique isotopomers useful for pathway identifications) have revealed the operations of the Entner–Doudoroff pathway, the reverse tricarboxylic acid cycle, new enzymes for biosynthesis of central metabolites, diverse respiration routes in phototrophic metabolism, co-metabolism of carbon nutrients and novel CO₂ fixation pathways. This review also discusses new isotopic methods to map carbon fluxes in global metabolisms, as well as potential factors influencing the metabolic flux quantification (e.g. metabolite channelling, the isotopic purity of ¹³C substrates and the isotopic effect). Although ¹³C labelling is not applicable to all biological systems (e.g. microbial communities), recent studies have shown that this method has a significant value in functional characterization of poorly understood micro-organisms, including species relevant for biotechnology and human health.     

Informetrics of Scientometrics abstracts: a rhetorical move analysis of the research abstracts published in Scientometrics journal

Scientometrics - The research abstracts have significant functions in the process of conveying information about each research. This is much important in the scientometrics field due to the...     

Conserving energy in domestic refrigerators through the use of refrigerant mixtures

Domestic refrigerators perform refrigeration at two temperature levels, so an applicable refrigeration cycle is one that employs two evaporators. If a refrigerant mixture is used in the circuit and directed in series first through the low- and then the high-temperature evaporator, the progressively rising temperatures reduce the irreversibilities in the cycle.The paper provides a literature review and then a series of simulations of several different cycles with varying mixtures of refrigerants. The analysis showed a possibility of saving approximately 12% compressor power by using a 50/50% mixture of Refrigerant 12/Refrigerant 114 in comparison to pure Refrigerant 12.     

Space-variant optical interconnection through the use of computer-generated holograms

A space-variant optical interconnection through the use of computer-generated holograms is proposed, and specific configurations to increase the number of parallel channels are analyzed. To this end, the well-known method based on a matrix composed of subholograms is applied. The field diffracted by each channel (assumed to be square apertures) is calculated through the angular-spectrum technique, and the resulting fields are suitably superimposed to obtain a hologram matrix with a reduced bandwidth. Results show that a compact transmissive planar configuration can be handled; in particular, the small interconnect distance between the array planes and the hologram yields a limited system volume.     

Improved author profiling through the use of citation classes

The method of Characteristic Scores and Scales (CSS), previously developed for application at the macro- and meso-level, has been applied to individual author statistics. In particular, two datasets have been used. Firstly, authors with Thomson Reuters Researcher-ID, independently of the field where authors are publishing and, secondly, authors who are active in the field of scientometrics, independently whether they are registered authors or not. The objective is to find a parameter-free solution for citation-impact assessment at this level of aggregation that is insensitive to possible outliers. As in the case of any statistics, the only limitation is the lower bound, which has been set to 10 for the present analysis. The results demonstrate the usefulness of the CSS method at this level while also pointing to some remarkable statistical properties.     

Midinfrared modulation through the use of field-induced scattering in ferroelectric liquid crystals

The feasibility of the use of modulation devices based on field-induced transient scattering in ferroelectric liquid crystals (LC) to replace mechanical choppers used in uncooled infrared-imaging systems was investigated. Devices fabricated with ITO-coated ZnSe substrates and a ferroelectric LC path length of 25 μm were able to modulate optical radiation by transient forward scattering at rates approaching 20 kHz. Through the use of a commercial arbitrary waveform generator and associated PC-based software, drive waveforms were developed that produced a variable, square-wave optical-modulation pattern by the extension of the duration of the scattering state to periods ranging from hundreds of microseconds to milliseconds. The ability of these extended-scattering-mode (ESM) devices to modulate radiation in both the visible and midinfrared regions was verified in a simple experiment through the use of a Fourier-transform infrared spectrometer, in which an unoptimized ESM device displayed a 40% modulation dep th for IR radiation in the 8-12-μm region.     

Determination of SBA-15 acidity through n-butyl amine TPD: a theoretical and experimental study

In this study, the interaction ways between n-butyl amine and SBA-15 molecular sieve were evaluated when the TPD technique is carried out to determine the total acidity of that solid. Experimental results (FTIR, TG/DTG, total acid, and catalytic activity) and theoretical calculations demonstrated that the n-butyl amine, used as probe molecule to total acidity determined by TPD, can act as acid or base depending on the nature and force of the active sites on SBA-15.     

The use of S&T indicators in science policy: Dutch experiences and theoretical perspectives from policy analysis

The relation between bibliometrics and science policy remains underdeveloped. Relevance of new methods to produce indicators is easily claimed, but often without real insight in the policy processes. Drawing on experiences with the use of S&T indicators in science policy in the Netherlands and on principal-agent theory, I develop an analytical perspective which enbles to assess the role of S&T indicators in science policy. It is argue that the use of S&T indicators can only be understood well if one takes the socio-political context with its specific dynamics and rationalities into account.     

Experimental and theoretical study of skylight polarization transmitted through Snell's window of a flat water surface

The celestial polarization pattern may be scrambled by refraction at the air-water interface. This polarization pattern was examined in shallow waters with a submersible polarimeter, and it was calculated by using land measurements ('semiempirical predictions') and models of the skylight polarization. Semiempirically predicted and measured e-vector orientations were significantly similar. Conversely, predicted percent polarization was correlated but lower than measurements. Percent polarization depended on wavelength, where at high sun altitudes maximal percent polarization generally appeared in the UV and red spectral regions. The wavelength dependency of polarization may lead to differential spectral sensitivity in polarization-sensitive animals according to time and type of activity.