bluuebunny/crossref_metadata_2025 huggingface dataset:
Chilocoris capensis n. sp., the first species of the genus Chilocoris Mayr, 1865 (Hemiptera: Heteroptera: Cydnidae) recorded in the Republic of South Africa with an annotated checklist of South African burrower bugs
Authors: LIS JERZY A. , LIS BARBARA , COMPTON STEPHEN G.
Published: August 2016

Chilocoris capensis n. sp. collected from fallen ripe figs of broom cluster fig Ficus sur Forsskål, 1775, the first burrower bug species of the genus Chilocoris Mayr, 1865 recorded in the Republic of South Africa, is described and compared with Chilocoris laevicollis Horváth, 1919, the morphologically most closely allied Afrotropical species. Additionally, an annotated checklist of burrower bug species recorded in the Republic of South Africa is provided. The known biology of Afrotropical Chilocoris species is briefly summarized.
Idealized Large-Eddy and Convection-Resolving Simulations of Moist Convection over Mountainous Terrain
Authors: Panosetti Davide , Böing Steven , Schlemmer Linda , Schmidli Jürg
Published: August 2016

On summertime fair-weather days, thermally driven wind systems play an important role in determining the initiation of convection and the occurrence of localized precipitation episodes over mountainous terrain. This study compares the mechanisms of convection initiation and precipitation development within a thermally driven flow over an idealized double-ridge system in large-eddy (LESs) and convection-resolving (CRM) simulations. First, LES at a horizontal grid spacing of 200 m is employed to analyze the developing circulations and associated clouds and precipitation. Second, CRM simulations at horizontal grid length of 1 km are conducted to evaluate the performance of a kilometer-scale model in reproducing the discussed mechanisms.

Mass convergence and a weaker inhibition over the two ridges flanking the valley combine with water vapor advection by upslope winds to initiate deep convection. In the CRM simulations, the spatial distribution of clouds and precipitation is generally well captured. However, if the mountains are high enough to force the thermally driven flow into an elevated mixed layer, the transition to deep convection occurs faster, precipitation is generated earlier, and surface rainfall rates are higher compared to the LES. Vertical turbulent fluxes remain largely unresolved in the CRM simulations and are underestimated by the model, leading to stronger upslope winds and increased horizontal moisture advection toward the mountain summits. The choice of the turbulence scheme and the employment of a shallow convection parameterization in the CRM simulations change the strength of the upslope winds, thereby influencing the simulated timing and intensity of convective precipitation.
The Resolution Dependence of Contiguous U.S. Precipitation Extremes in Response to CO2 Forcing
Authors: van der Wiel Karin , Kapnick Sarah B. , Vecchi Gabriel A. , Cooke William F , Delworth Thomas L. , Jia Liwei , Murakami Hiroyuki , Underwood Seth , Zeng Fanrong
Published: August 2016

Precipitation extremes have a widespread impact on societies and ecosystems; it is therefore important to understand current and future patterns of extreme precipitation. Here, a set of new global coupled climate models with varying atmospheric resolution has been used to investigate the ability of these models to reproduce observed patterns of precipitation extremes and to investigate changes in these extremes in response to increased atmospheric CO2 concentrations. The atmospheric resolution was increased from 2° × 2° grid cells (typical resolution in the CMIP5 archive) to 0.25° × 0.25° (tropical cyclone permitting). Analysis has been confined to the contiguous United States (CONUS). It is shown that, for these models, integrating at higher atmospheric resolution improves all aspects of simulated extreme precipitation: spatial patterns, intensities, and seasonal timing. In response to 2 × CO2 concentrations, all models show a mean intensification of precipitation rates during extreme events of approximately 3%–4% K−1. However, projected regional patterns of changes in extremes are dependent on model resolution. For example, the highest-resolution models show increased precipitation rates during extreme events in the hurricane season in the U.S. Southeast; this increase is not found in the low-resolution model. These results emphasize that, for the study of extreme precipitation there is a minimum model resolution that is needed to capture the weather phenomena generating the extremes. Finally, the observed record and historical model experiments were used to investigate changes in the recent past. In part because of large intrinsic variability, no evidence was found for changes in extreme precipitation attributable to climate change in the available observed record.
Enhanced Turbulence Associated with the Diurnal Jet in the Ocean Surface Boundary Layer
Authors: Sutherland Graig , Marié Louis , Reverdin Gilles , Christensen Kai H. , Broström Göran , Ward Brian
Published: August 2016

Detailed observations of the diurnal jet, a surface intensification of the wind-driven current associated with the diurnal cycle of sea surface temperature (SST), were obtained during August and September 2012 in the subtropical Atlantic. A diurnal increase in SST of 0.2° to 0.5°C was observed, which corresponded to a diurnal jet of 0.15 m s−1. The increase in near-surface stratification limits the vertical diffusion of the wind stress, which in turn increases the near-surface shear. While the stratification decreased the turbulent dissipation rate ε below the depth of the diurnal jet, there was an observed increase in ε within the diurnal jet. The diurnal jet was observed to increase the near-surface shear by a factor of 5, which coincided with enhanced values of ε. The diurnal evolution of the Richardson number, which is an indicator of shear instability, is less than 1, suggesting that shear instability may contribute to near-surface turbulence. While the increased stratification due to the diurnal heating limits the depth of the momentum flux due to the wind, shear instability provides an additional source of turbulence that interacts with the enhanced shear of the diurnal jet to increase ε within this shallow layer.
Booms, busts and parochialism
Authors: Beeson Mark
Published: August 2016

Western Australia (WA) has recently assumed an unaccustomed centrality in the minds of Australian policymakers. The recent resource boom briefly propelled WA to the forefront of national economic affairs. While this proved a relatively short-lived prominence, the emergence of WA at the centre of a putative ‘Indo-Pacific’ region promises to give it a more enduring strategic significance. This paper details how geopolitical and geoeconomic forces have shaped WA’s developmental history, and why they are likely to do so in the future as well.
The not-so-barren ranges
Authors: Scott Kim
Published: August 2016

This is an impressionistic and informal essay written near the end of a novelist’s Australia Research Council funded research project: ‘Developing narratives from language and stories indigenous to the south coast of Western Australia’, and informed by how that research project morphed into an emphasis on revitalization of Noongar language, and the attempt to restore connections between a particular Creation Story and landscape in an area regarded as ‘massacre territory’. A sympathetic reader might think of the topic as ‘The Wirlomin Noongar Language and Stories Project meets The Barren Ranges’.
Ugly town
Authors: Gorman Sean
Published: August 2016

In considering the historical treatment of Aboriginal Australians this paper will discuss the different spaces operating in Western Australia’s South West in the late 1920s and the government policies that fed into them. These are the Moore River Native Settlement that is located some 100 km north of Perth and White City, a carnival sideshow located at the bottom of William Street on the banks of the Swan River in Perth. The 1905 Aborigines Act and a provision within that act known as the Proclamation of the Prohibited Area of Perth will be discussed. This will be done by comparing the ways that White City was seen by the government in the 1920s and how in recent years Northbridge has been regulated and discursively constructed. The intent is to look at how Aboriginal people have been treated over time and consider the social, historical and political forces that have shaped that construction.
Commonplacing the public domain: Reading the classics socially on the Kindle
Authors: Rowberry Simon Peter
Published: August 2016

Amazon leads the market in ebooks with the Kindle brand, which encompasses a range of dedicated e-reader devices and a large ebook store. Kindle users are able to share the experience of reading ebooks purchased from Amazon by selecting passages of text for upload to the Kindle Popular Highlights website. In this article, I propose that the Kindle Popular Highlights database contains evidence that readers are re-appropriating commonplacing – the act of selecting important passages from a text and recording them in a separate location for later re-use – while reading public domain titles on the Kindle. An analysis of keyness in a corpus of 34,044 shared highlights from public domain titles suggests that readers focus on words relating to philosophy and values to draw an understanding of contemporary society from these classic works. This form of highlighting takes precedence over understanding and sharing key narrative moments. An examination of the top ten most popular authors in the corpus, and case studies of Jane Austen’s Pride and Prejudice and William Shakespeare’s Hamlet, demonstrate variation in highlighting practice as readers are choosing to shorten famous commonplaces in order to change their context for an audience that extends beyond the original reader. Through this analysis, I propose that Kindle users’ highlighting patterns are shaped by the behaviour of other readers and reflect a shared understanding of an audience beyond the initial highlighter.
‘What about the wolves?’: The use of scripture in YouTube arguments
Authors: Pihlaja Stephen
Published: August 2016

Reading and interpreting the Bible is an important practice in Evangelical Christian communities, both online and offline. Members of these communities employ biblical exegesis not only in convincing others about the validity of their beliefs, but also influencing the development of the social context in which they interact. Thus, reading and interpretation of the Bible serves both a theological purpose, allowing users to provide textual evidence for beliefs, and a practical social purpose, allowing users to map their own and others’ actions onto biblical texts, either to condone or to condemn them. For users who hold the same belief about the importance of the Bible in making moral judgements, the biblical text can be a particularly useful tool to position oneself and one’s actions. In this article, I employ concepts from positioning theory, to analyse how Evangelical Christian YouTube users read across the books of the Bible by treating similar uses of metaphorical language as interchangeable, and using them to position particular users and to make moral judgements about their actions. The analysis shows that reading and exegesis of scripture can be used in dynamic online environments to map characters and storylines from diverse biblical passages onto a particular online argument, providing a common resource for users from different backgrounds and contexts. Findings show that reading and interpretation of scriptures provide a powerful means of claiming authority for Evangelical Christians in the community, and are used to position oneself and one’s actions, influencing the subsequent discourse and emerging social context.
Partial Loss of Function of the GHRH Receptor Leads to Mild Growth Hormone Deficiency
Authors: Gregory Louise Cheryl , Alatzoglou Kyriaki Sandy , McCabe Mark James , Hindmarsh Peter Christopher , Saldanha Jose William , Romano Nicola , Le Tissier Paul , Dattani Mehul Tulsidas
Published: August 2016

Objective:

Recessive mutations in GHRHR are associated with severe isolated growth hormone deficiency (IGHD), with a final height in untreated patients of 130 cm ± 10 cm (−7.2 ± 1.6 SDS; males) and 114 ± 0.7 cm (−8.3 ± 0.1 SDS; females).

Design:

We hypothesized that a consanguineous Pakistani family with IGHD in three siblings (two males, one female) would have mutations in GH1 or GHRHR.

Results:

Two novel homozygous missense variants [c.11G>A (p.R4Q), c.236C>T (p.P79L)] at conserved residues were identified in all three siblings. Both were absent from control databases, aside from pR4Q appearing once in heterozygous form in the Exome Aggregation Consortium Browser. The brothers were diagnosed with GH deficiency at 9.8 and 6.0 years (height SDS: −2.24 and −1.23, respectively), with a peak GH of 2.9 μg/liter with low IGF-1/IGF binding protein 3. Their sister presented at 16 years with classic GH deficiency (peak GH <0.1 μg/liter, IGF-1 <3.3 mmol/liter) and attained an untreated near-adult height of 144 cm (−3.0 SDS); the tallest untreated patient with GHRHR mutations reported. An unrelated Pakistani female IGHD patient was also compound homozygous. All patients had a small anterior pituitary on magnetic resonance imaging. Functional analysis revealed a 50% reduction in maximal cAMP response to stimulation with GHRH by the p.R4Q/p.P79L double mutant receptor, with a 100-fold increase in EC50.

Conclusion:

We report the first coexistence of two novel compound homozygous GHRHR variants in two unrelated pedigrees associated with a partial loss of function. Surprisingly, the patients have a relatively mild IGHD phenotype. Analysis revealed that the pP79L mutation is associated with the compromise in function, with the residual partial activity explaining the mild phenotype.
Structure formation in surface layer of machine parts by methods of high-vacuum annealing and ion implantation
Authors: Шалыгин Михаил , Shalygin Mikhail
Published: August 2016

This paper reports the problems of hydrogen wear decrease in steel parts operating in hydrogen medium. The friction couples of particular machine parts subjected to hydrogen wear are shown. Steel grades of the samples analyzed and their hardness are pointed out. The technologies of high- vacuum annealing and ion implantation used in investigations are de-scribed. The modes for the carrying out of high-vacuum annealing and ion implantation of silicon into a surface of the samples investigated are presented. It is determined that in a surface layer after the carrying out of high-vacuum annealing and ion implantation appear new structures with their form similar to roundish spots. The dimensions of spots and their distribution according to depth are defined. The sample breaking tests are carried out. It is established that technological operations carried out affect only the surface layers of samples. The investigation results can be used at the analysis of methods for hydrogen wear decrease of parts operating in hydrogen medium.
Development of additive technological method for gas-powder laser surfacing process
Authors: Порошин Валерий , Poroshin Valeriy , Богданов А. , Bogdanov A. , Зябрев Игорь , Zyabrev Igor
Published: August 2016

The methods of additive techniques of layer-by-layer laser agglomeration of powder materials at a direct injection and mechanical powder feed are considered. A method for layer-by-layer surfacing with a scanning laser beam is offered. The paths of scanning on a line, ellipse and a circle are analyzed. Samples are processed and investigations on an influence of a processing velocity and the paths of scanning upon geometrical adjectives of layers obtained are carried out. The investigation results obtained allowed drawing a conclusion of the optimality of a scanning path of a laser beam on an ellipse, on geometrical adjectives and a coefficient of powder use.
Development of Value Paradigm in Management
Authors: Серебрякова  , Syeryebryakova Galina
Published: August 2016

The article describes the need of formation and use of the organizational and economic mechanisms

promoting strengthening of spiritual and moral components in the administrative environment. Besides, the

special attention is paid to a question of interaction in the company which lays the foundation of valuable

management of social and economic systems. Article is written on the basis of materials, received from the

research work within the framework of the state task of the Ministry of education and science of the Russian

Federation.
The Emphasis of the Development of the Scientific School of Management Theory
Authors: Мусаелян  , Musaelyan I.
Published: August 2016

The article analyzes current trends in the development of the scientific school of management theory. The

author has tried to highlight the most important problem areas in the field of modern management. Focusing

on the problems of cultural contents, functional management and processes of development, adoption and

implementation of managerial decisions, the author examines the state and comes to the conclusion that

modern management is need to be systematized, and sometimes to re-examine views.
View from the Past – the Way to the Future
Authors: Мельник  , Melnik M.
Published: August 2016

This article describes the main developments and results of the emergence, formation and development of

the scientific school of management theory. The article estimated place, role, contribution of the scientific

school of State University of Management to the improvement and development of the theory and practice

of management of the national economy of Russia.
School Management
Authors: Зотов  , Zotov V.
Published: August 2016

Planning, preparation, defending doctorate thesis, not accidentally for the majority of onlookers seems to

be an extremely complex, time-consuming, lengthy task, the formulation and the solution of which is not

available for every researcher, the more serious the busy practice manager. The media, including foreign

ones, traditionally prevailing public opinion steadily form an idea of what scientific degree of heads of large

state or business organizations do not always result from the activities of their authors. A specific story

about how, in the framework of the scientific school of management theory at the department of theory

of organization and management of the State University of Management was prepared and defended the

dissertation of doctor of economic sciences, acting prefect of the southeastern administrative district of

Moscow, Zotov Vladimir Borisovich gives an exhaustive answer to this question.
Madame “Paradigm”
Authors: Алешникова  , Aleshnikova V.
Published: August 2016

The article analyzes the role of the doctor of economic sciences, Professor of Department of theory of

management, honored worker of science of the Russian Federation Z.P. Rumyantsev in the development

of the theory and practice of the Russian school of management; contribution to the training of the teaching

staff. The article provides a wide range of real-world examples, professional characteristics, individual

assessment of his joint work with the aspirate and students in the framework of formation and development

of the scientific school of management theory. The authors share personal observations and impressions

formed in the course of preparation and protection of dissertations on competition of a scientific degree of

candidate of economic Sciences under the direct scientific leadership of Zinaida Petrovna Rumyantseva.
Variação morfométrica de arcídeos (Mollusca: Bivalvia) da costa norte-nordeste do Brasil
Authors: Rocha Valesca Paula , Matthews-Cascon Helena
Published: August 2016

O objetivo do estudo é complementar a literatura sobre a família Arcidae, onde foi utilizado o enfoque morfométrico – que permite a comparação de padrões morfológicos a partir de caracteres multivariados. Os espécimes disponíveis para o estudo são provenientes da Coleção Malacológica “Prof. Henry Ramos Matthews” (CMPHRM), da Universidade Federal do Ceará, onde foram utilizadas a valvas direitas. Após identificação foram tomadas oito medidas: comprimento da charneira, comprimento da concha, posição do umbo (prodisoconcha), altura do umbo (prodisoconcha), altura da porção anterior da concha, altura média da concha, altura da porção posterior da concha e comprimento da porção posterior da concha. As medidas são previamente conhecidas como ‘marcos anatômicos’ da família. Os dados foram analisados em pacotes estatísticos e as médias dos tamanhos das conchas apresentaram-se coerentes as medidas apresentadas na literatura. Algumas medidas foram significantes na diferenciação das espécies estudadas. Os espécimes analisados, que possuem proximidade geográfica, apresentam similaridade morfológica.
The influence of the Greek novel on the Life and Miracles of Saint Thecla
Authors: Narro Ángel
Published: August 2016

The Life and Miracles of Saint Thecla, a 5th-century hagiographical work, feature many elements recalling the ancient novel. Even if the first part of the text, the Life, must be considered a novel itself due to its dependence on the model of the Acts of Paul and Thecla, some novelistic motifs - especially the use of descriptions, digressions and first-person narrations − appear throughout the whole text. In addition, we also examine the textual evidence of the influence of the ancient novel on this hagiographical text through the analysis of some lexical details which suggest the reading of the ancient novels. The hagiographer uses these elements to rewrite in same cases the original scene of the Acts of Paul and Thecla or to evoke in other scenes the universe of the ancient novel in order to delight his readers.
Der wissende Pilger und der unwissende Reisende. Eine kursorische Lektüre des XXVI. Gesangs von Dantes Inferno
Authors: Huss Bernhard
Published: August 2016

Riassunto

Questa lettura cursoria si propone di trattare il fondamentale problema del giudizio etico sul viaggio atlantico di Ulisse partendo dall’assunto che lo stesso Ulisse viene destinato da Dante alla condanna infernale e che le ragioni di tale scelta punitiva sono tuttora estremamente discusse dalla critica. Dal racconto autodiegetico dell’ultima azione della sua vita emerge l’immagine di un Ulisse viaggiatore ›inconsapevole‹: un uomo temerario di epoca precristiana, a cui manca necessariamente, così come al suo interlocutore Virgilio, qualsiasi tipo di ancoraggio teologico e di fede nella salvezza ultraterrena. Sulla base soprattutto della situazione comunicativa instauratasi nel canto XXVI, che esclude ›Dante‹, pellegrino consapevole, dal colloquio del poeta epico pagano con gli eroi epici dell’antichità precristiana, si mette qui in evidenza come il canto intenda fornire l’esplicita rappresentazione di un dislivello informativo escatologicamente determinato (ed escatologicamente determinante). Soltanto all’orizzonte conoscitivo cristiano si dischiude la consapevolezza che il pagano Ulisse, scaltrito e abilissimo negli inganni, si converte con la sua traversata marittima in un uomo ingannato e fuorviato, al quale la cognizione del vero significato del proprio agire rimane costantemente inattingibile persino nell’inferno.
Stefan Zweig und Dante Alighieri
Authors: Larcati Arturo
Published: August 2016

Riassunto

In questo saggio si ricostruisce per la prima volta l’interesse di Stefan Zweig per Dante, che è rimasto costante durante tutta la sua vita. Lo scrittore austriaco, che aveva intenzione di tradurre in tedesco la Vita Nova, non solo imita lo stile di Dante in una composizione giovanile dal titolo »Tal der Trauer« (»Valle della tristezza«, 1905), ma promuove anche una nuova edizione delle sue opere in lingua originale (col commento di Croce) presso la casa editrice Insel di Lipsia nel 1921 e più tardi esalta il poeta italiano come sostenitore di valori umanistici. Negli anni in cui Zweig è costretto a lasciare l’Austria a causa del Nazismo (1934-1942), l’autore della Commedia diventa uno dei punti di riferimento più importanti per una nuova concezione della letteratura d’esilio.
Compact Dual-band Bandpass Filter Based on HMSIW and DS-CSRR
Authors: Kang Hong Yi , Song Jing Pan , Li Jiao , Wei Feng
Published: August 2016

A compact dual-band bandpass filter (BPF) based on a half-mode substrate integrated waveguide (HMSIW) and double-side complementary split-ring resonators (DS-CSRR) is investigated in this paper. The proposed DS-CSRR consists of two complementary split-ring resonators (CSRRs) with different sizes. One is etched on the top surface of HMSIW, the other is on the ground. By changing the parameters of DS-CSRR, both the center frequencies and the bandwidths can be controlled independently, respectively. In order to validate its practicability, a dual-band BPF centered at 3.5 GHz/5.2 GHz is designed and demonstrated. The simulated and measured results are in good agreement with each other.
Analysis, Simulation and Optimization of the Milking Process in a Cowshed for the Production of Parmigiano Reggiano
Authors: Armenzoni Mattia , Bottani Eleonora , Rinaldi Marta , Gallo Sergio Amedeo , Montanari Roberto
Published: August 2016

The aim of this study is to optimize the milking process of a cowshed, located near Parma (Italy), which provides milk to some dairy companies, for the production of Parmigiano Reggiano cheese. The ultimate goal of the analysis is to reduce the time required for milking operations, thus optimizing the whole management of the farm processes. A discrete-event simulation model is designed under Simul8™ to reproduce the main processes of the cowshed and the movements of the animals inside the cowshed, before and after milking. The model exploits real data collected from the direct observation of the farm and is validated by comparing the results provided with the real performance of the milking activities. Then, it is used to test two new configurations of the cowshed layout and to assess their performance, in terms of the total time required for milking. Interesting savings in the total milking time are found.
Phases of Thin Colloidal Layers
Authors: Murray Cherry
Published: August 2016

Colloids have long been used in applications such as paints, coatings, foods, and many manufacturing processes. Recently, synthetic crystalline arrays of colloidal particles have been used as novel optical materials such as diffractive filters, mimicking the optical properties of opals—natural colloidal crystals made from silica spheres. Colloidal assembly has been proposed to manufacture photonic bandgap materials that can be tailored and that could have many uses in optical devices. The advantages of using colloids to do the self-assembly of novel materials are the relative ease with which monodisperse spheres comparable in size to the wavelength of light can be manufactured and also the demonstrated ease by which some suspensions of monodisperse colloidal spheres crystallize when placed under favorable conditions. Before we can use colloidal crystallization as a controlled self-assembly technique for making novel optical materials, we need (1) to create a means of manufacturing large quantities of monodisperse particles of the desired dielectric behavior, (2) to understand the phase diagram and nucleation phenomena of colloidal suspensions, and (3) to find an easy means to fix the particles in place once they selforganize. In this article, I focus on the second point just mentioned, I give an overview of the phases and some of the complex phenomena encountered in three-dimensional (3D) suspensions and in thin layers of monodisperse colloidal spheres between smooth walls, and I then briefly mention the greater complexity encountered in bidisperse systems. The first and third points will be dealt with elsewhere in this issue.
From the de Broglie to Visible Wavelengths: Manipulating Electrons and Photons With Colloids
Authors: van Blaaderen Alfons
Published: August 2016

Because of their size and ability to selforganize, colloidal particles are ideal building blocks for the creation of three-dimensional (3D) structures that can have feature sizes of the order of the wavelength of electrons, photons, or both. This article is too short to provide an extensive literature survey but instead will give some illustrative examples, based on work of the author and co-workers, of how specially developed core-shell particles might be organized on a 3D lattice. These examples are only intended to give an impression of how colloidal-particle systems can be used in the design of new materials with interesting photonic properties.

Generally particles are considered colloidal if their size is between several nm and several μm. This range is more or less defined by the importance of Brownian motion—that is, the irregular, overdamped, random displacements the particles make as a result of the not completely averaged-out bombardment of solvent (or gas) molecules. Consequently the lower size range is determined by the size of the solvent molecules. Compared to the particle size, the solvent molecules need to be so small that the time scales of the solvent molecules and particles are so far apart that the solvent molecules can be “integrated out” in a description of the particles. If such a description holds, the solvent can be approximated well by a continuum. The upper size limit is determined by the size at which external fields, like gravity, start to overshadow the effects of Brownian motion.
Historical Note: Bicycles Roll Along from Wooden Wagon Wheel to Alloy Tubing
Authors: McMahon C.J.
Published: August 2016

The evolution of the bicycle provides a good history of structural materials since the 1850s. The first machine that resembled a bicycle was made of a wooden beam with a wooden wagon wheel at each end. This presumably inspired the Hobby Horse, which had a forged iron beam for a frame, along with wooden wheels. The next step was the “boneshaker,” still with wooden wheels, but with the innovation of pedals, which allowed riders to keep their feet off the ground. Major reductions in weight came with the introduction of steel tubing for the frame and tensioned wire-spoke wheels, as in the high-wheelers of the 1880s. These breakthroughs came on the heels of the development of tube drawing and wire drawing in the new steel industry. With the introduction of the Humber “safety bicycle” in 1890, the evolution of the present-day diamond-frame configuration of the bicycle was completed. By this time, hardened steel components were available for the chain, cogs, bearings, and the chain wheel. In the previous year, John Dunlop had patented the pneumatic tire, and this invention took over the market for bicycle tires by 1895. The cotton-fiber-strengthened rubber-matrix tire was probably one of the earliest fabricated composite materials.

The use of brazing to join the cold-drawn steel tubes led to the development of the diamond frame. Lugs held the ends of the tubes in place. The brazing alloys were, and still are, based on Cu-40%Zn and on the Ag-Cu eutectic alloy. Wood and bamboo were tried as substitutes for steel tubes in diamond frames during the past century, but the lack of an available method for joining the pieces together defeated these attempts to save weight. The main materials developments in bicycles over the next 80 or 90 years after the Humber safety were the introduction of low-alloy steels for tubing, primarily the Cr-Mo-0.3%C 4130-type steel, the substitution of aluminum-alloy extrusions for steel tubing for wheel rims after the 1950s, and the use of stainless-steel spokes instead of carbon steel.
Silicon-Based Metal-Semiconductor-Metal Detectors
Authors: Buchal Ch. , Löken M.
Published: August 2016

Photodetectors must provide fast and efficient conversion of photons to charge carriers. When considering semiconductor light sources, the indirect bandgap of silicon and germanium represents a serious obstacle to radiative electron-hole recombinations. Momentum conservation demands the simultaneous interaction of the electron-hole pair with a momentum-matching phonon. As a consequence, radiative recombinations are five orders of magnitude less probable in Si if compared to a direct semiconductor such as GaAs.

Although the absorption of a photon and the generation of an electron-hole pair may be considered as the inverse process to emission, photon absorption within indirect semiconductors is a highly probable process if the photon energy is sufficient to bridge the energy gap in a direct process. The resulting electronhole pair is created in an excited state and relaxes sequentially. The ubiquitous-silicon solar cells operate this way. In the visible spectral range, Si photodetectors have demonstrated fast and efficient performance, being readily adapted for opto electronic applications and being fully compatible to standard-silicon processing schemes.
Fundamentals of Friction
Authors: Krim Jacqueline
Published: August 2016

By most recent estimates, improved attention to friction and wear would save developed countries up to 1.6% of their gross national product—over $100 billion annually in the United States alone. It is thus not surprising that tribomaterials, materials designed for use in moving contact (sliding, rolling, abrasive, etc.) have for decades attracted the interests of materials scientists and mechanical and chemical engineers. However the field of tribology is hardly a recent one. Such tribological advances as Leonardo da Vinci's design of intricate gears and bearings (some of which were not built until the Industrial Revolution provided sufficiently strong materials) and the landmark 18th century development of a timepiece allowing accurate longitudinal positioning of ships at sea (accomplished via a self-lubricating wooden gear) could easily be termed “modern,” given the overall longevity of the field.

As important as tribomaterials are to technology, their discovery has usually been serendipitous. Materials scientists have frequently been able to provide explanations for why tribomaterials perform as well as they do. They have also been able to substantially improve the performance of tribomaterials through the development of new alloys, composites, and/or improved surface-engineering methods. They have however been far less successful at a priori design of tribomaterials with improved performance, largely because friction and wear processes have not been understood at the fundamental level.

The late 1980s marked the advent of renewed interest in fundamental areas of tribology, sparked by a number of new experimental and theoretical techniques that made it possible to study the force of friction in geometries that are well-defined at the nanometer scale.
Friction in the Presence of Molecular Lubricants and Solid/Hard Coatings
Authors: Harrison Judith A. , Perry Scott S.
Published: August 2016

Two of the most widely employed approaches for enhancing the lifetime and tribological performance of mechanical devices involve the introduction of lubricants and solid/hard coatings to the interface between two contacting surfaces. These approaches have been employed for centuries, and their design has been widely accomplished through empirical methods. In the last 20 years however, the general trend of device miniaturization and the development of advanced technology applications have placed more stringent demands on the performance of many tribological interfaces. For example, many of the hard-disk storage products now shipped in computers rely upon a single layer of lubricant molecules adsorbed on a submicron-thick layer of amorphous carbon to control the static friction and wear between the read/write head and the disk surface. In other advanced technologies, hard-coating materials are introduced into tribological interfaces that will operate in remote or harsh environments to improve the durability and lifetime of the devices. In the previous examples, the introduction of a thin coating or a change in surface composition dramatically influences the tribological properties and indicates that many tribological interfaces can be understood and described on a molecular scale. This article will review recent progress made in understanding the molecular events associated with tribological phenomena from both experimental and theoretical approaches.

In general, advances in experimental studies have been realized through developing a greater sensitivity to the relatively few number of species found within a tribological contact.
Stimulation of Biological Function With Bioactive Glass
Authors: Ducheyne Paul
Published: August 2016

An estimated 11 million people in the United States have at least one medical-device implant. Orthopedic implants account for 51.3% of all implants. They include fixation devices (usually fracture fixation) and artificial joints, used in 77% and 23% of the cases, respectively. Among the joint-replacement procedures, hip and knee surgeries represent 90% of the total and in 1988 were performed 310,000 times in this country. Currently more than half the joint-reconstruction devices are used with bone cement, which is a polymer grout that keeps the prosthesis components in place in the bone. The fixation in the other cases depends on the bone's ability to grow in contact with the device. This can be achieved by making the prosthesis surface porous such that bone grows into interstices or by making the surface chemically reactive with bone tissue such that a continuous, uninterrupted transition is formed from tissue to device. Bioactive glasses (BGs) and ceramics are the materials of choice to achieve this effect on bone-tissue bonding. Bone-growth stimulation is also sought in the treatment of difficult fractures. In the United States alone, there are 1.23 million fractures that require a bone plate. Of that total, approximately 1 million require between 10 cm3and 100 cm3of graft material to stimulate bone repair. At this time, autogenous bone graft represents the gold standard: This graft is typically bone tissue taken from the patient's own pelvic bone. Given the morbidity associated with this procedure and the frequently insufficient quantities available, extensive efforts for suitable alternatives are currently under way. Calcium phosphate ceramics and glasses, either by themselves or as carriers for bone (or “osteogenic”) cells or various bone-growth factors, are also prime candidates for these applications.
High-Resolution Spectroscopy of Individual Quantum Dots in Wells
Authors: Gammon Daniel
Published: August 2016

Currently spectroscopists are studying many semiconductor quantum-dot (QD) systems in great detail because of their scientific and technological importance. However as in all nanostructure systems in which significant confinement energies exist, size fluctuations lead to inhomogeneous broadening of the spectral lines. This blurring of the spectra severely reduces the amount of information obtainable from spectroscopy. The finding has initiated an effort to isolate optically and study spectroscopically individual QDs. Studies involving individual QDs in most QD systems have been published. Here the results of a series of experiments are reviewed on GaAs QDs defined by interface fluctuations in narrow GaAs quantum wells. These experiments demonstrate the elegance and potential of single-QD spectroscopy.

An example of single-QD photoluminescence (PL) spectroscopy appears in Figure 1. The spectra shown were obtained at a temperature of 6 K by successively reducing the size of the laser spot on a GaAs quantum-well sample through the use of small apertures in a metal mask. The bottom trace is a PL spectrum obtained with a macroscopic laser spot diameter of 25μm. The spectrum shows two broad peaks corresponding to the recombination of excitons in parts of the quantum well that are either 10 or 11 monolayers wide (2.8 or 3.1 nm). The spectrum is strongly inhomogeneously broadened as shown most directly by a reduction in the aperture size. The relatively broad lines break up into a decreasing number of extraordinarily narrow PL spikes as the aperture is reduced to submicroscopic dimensions. These PL spikes arise from excitons localized in individual QD potentials. Remarkably the linewidth decreases from several meV in the ensemble-averaged spectrum (25-μm aperture) to 10s of μeV in the single QD spectra, corresponding to an effective improvement in resolution of two orders in magnitude. By probing individual QDs, it becomes possible to resolve directly a number of phenomena that previously were hidden in the inhomogeneous linewidth.
Nanoscale Scanning Force Imaging of Polarization Phenomena in Ferroelectric Thin Films
Authors: Auciello O. , Gruverman A. , Tokumoto H. , Prakash S.A. , Aggarwal S. , Ramesh R.
Published: August 2016

The science and technology of ferroelectric thin films is currently attracting worldwide attention because of its application to a new generation of novel devices. Prime, among these applications are nonvolatile ferroelectric random-access memories (NVFRAMs), which have high speed and extended endurance. The core of an NVFRAM is a capacitor with a ferroelectric film sandwiched between two electrode layers. The polarization of the ferroelectric layer in two possible opposite directions, upon application of an electric field between the two electrodes, provides the logic “1” and “0” states needed for binary-code memory. In spite of the advances in the science and technology of ferroelectric thin films and their integration into ferroelectric capacitors, some materials-related integration strategies as well as manufacturability issues have delayed commercialization of NVFRAMs. High-density memories require storage elements that approach submicron lateral dimensions. Thus, improved understanding of the materials properties and polarization phenomena is needed in conjunction with the development of new characterization tools that can enable such an understanding. For example, a fundamental issue in ferroelectric thin-film capacitors is the exact nature of the complex domain structure in the polarizable ferroelectric layer and its dynamics under high-speed switching conditions. The miniaturization of NVFRAMs requires understanding of granularity in polarization reversal dynamics, fatigue, and retention characteristics. In this respect, theoretical models and electrical measurements (e.g., polarization hysteresis loops and transient currents) have provided substantial insights into the nature of the switching processes. However, the models (phenomenological in nature) and the electrical measurements provide only a global or macroscopic view of the switching process.
Ultrasonic Characterization of Surfaces and Interphases
Authors: Rokhlin Stanislav I. , Matikas Theodore E.
Published: August 2016

Ultrasonic waves have been used extensively for material characterization and for sensing in material process control. The waves produce small-amplitude mechanical vibrations and, depending on the mode being used, may induce both longitudinal and shear stresses in the solid. Information on the structural properties of a substance can be obtained by measuring both the velocity and the attenuation of the ultrasonic wave. The phase velocity of the wave depends on the elastic constants and density of the body while attenuation depends on microstructure and crystalline defects.

In an isotropic solid medium, which has only two independent elastic moduli, there exist two elastic waves: the longitudinal and the shear. Three kinds of bulk elastic waves may propagate in an anisotropic solid: a quasilongitudinal and two quasitransverse waves, differing in polarization and velocity. To determine the set of elastic constants, one must measure the phase velocity in several different directions relative to the crystallographic axes.

The attenuation of an ultrasonic wave is associated with absorption of elastic waves (inelastic effect) and the scattering of elastic waves by structural inhomogeneities. Scattering may be the governing attenuation mechanism in polycrystalline, composite, and ceramic materials. As a result of scattering, elastic energy is lost by the prime ultrasonic beam in the form of a stochastically scattered field, which is gradually absorbed in the material. The latter is associated with conversion of elastic into thermal energy as a result of various inelastic effects termed internal friction.
From Photoacoustic Microscopy to Thermal-Wave Imaging
Authors: Thomas R.L. , Favro L.D.
Published: August 2016

Photoacoustic spectroscopy is a technique in which the absorption of periodically intensity-modulated light is detected by the sound that it produces at the (acoustic) modulation frequency in a closed volume of gas or liquid in thermal contact with the material absorbing the light. The spectroscopic aspect of the technique relies on the ability to scan the wavelength of the light that stimulates the sound. Thus one can determine the absorption as a function of wavelength through the conversion of absorbed energy to heat and thence to sound. The acoustic detection is carried out synchronously with respect to the imposed intensity-modulation frequency on the light, making it possible to use narrow-band noise reduction. The existence of this technique for detecting sound generated by the absorption of light led Wong and co-workers to investigate the possibility of using the same techniques for microscopy.
Tissue-Engineering Strategies for Ligament Reconstruction
Authors: Dunn Michael G.
Published: August 2016

The majority of musculoskeletal injuries involve the soft connective tissues including cartilage, meniscus, tendon, and ligament. In contrast to bone tissue, which regenerates after injury, these soft tissues tend to heal poorly through formation of weak, disorganized scar tissue. In fact certain soft-tissue injuries cannot heal on their own so surgical repair or complete reconstruction is required to restore function. Biological grafts (autografts and allografts) and “permanent” synthetic prostheses are currently used to reconstruct large soft-tissue defects. Autografts (a patient's own tissue transferred to another site) can be successful, but as you “rob Peter to pay Paul,” complications at the donor site can be significant. Allografts (transplants from another human) are in short supply and carry the risk of rejection or disease transmission. In general, permanent synthetic prostheses fail to withstand long-term mechanical loading associated with the musculoskeletal system. New strategies are clearly needed to manage musculoskeletal soft-tissue reconstruction.

Several tissue-engineering strategies are potentially useful to enhance repair of these troublesome injuries or to induce regeneration. One interesting approach (developed for skin and cartilage regeneration) combines scaffolds, cells, and cell signals to grow living tissue analogues in the laboratory. Scaffolds are natural or synthetic biomaterials upon which the cells attach and grow. The cells may be fibroblasts, chondrocytes, etc., depending on the specific application. Influential cell signals can include attachment factors, growth factors, and mechanical loads.

Our laboratory is developing a similar approach for ligament reconstruction. Ligaments are the strong, flexible bands of collagenous tissue that connect bone-to-bone to provide a delicate balance of stability and flexibility to the joints of the body. The anterior cruciate ligament (ACL) is the primary stabilizer of the knee and is frequently injured in sporting activities and accidents. Serious ACL injuries can lead to disability and progressive degeneration of cartilage and meniscus that normally serve as shock absorbers in the joint. Anterior-cruciate-ligament ruptures do not heal without surgical intervention, due to a poor intrinsic healing response and poor vascularity. To restore normal joint function, ruptured ACLs can be surgically reconstructed using a patellar-tendon autograft or allograft. While significant progress has been made in understanding ACL anatomy, structure, biomechanics, and healing, there is still no biological graft or biomaterial ideally suited for ACL reconstruction.