Defence Academy of the United Kingdom

Reduced graphene oxide (rGO)-conjugated Cu(2)O nanowire mesocrystals were formed by nonclassical crystallization in the presence of GO and o-anisidine under hydrothermal conditions. The resultant mesocrystals are comprised of highly anisotropic nanowires as building blocks and possess a distinct octahedral morphology with eight {111} equivalent crystal faces. The mechanisms underlying the sequential formation of the mesocrystals are as follows: first, GO-promoted agglomeration of amorphous spherical Cu(2)O nanoparticles at the initial stage, leading to the transition of growth mechanism from conventional ion-by-ion growth to particle-mediated crystallization; second, the evolution of the amorphous microspheres into hierarchical structure, and finally to nanowire mesocrystals through mesoscale transformation, where Ostwald ripening is responsible for the growth of the nanowire building blocks; third, large-scale self-organization of the mesocrystals and the reduction of GO (at high GO concentration) occur simultaneously, resulting in an integrated hybrid architecture where porous three-dimensional (3D) framework structures interspersed among two-dimensional (2D) rGO sheets. Interestingly, "super-mesocrystals" formed by 3D oriented attachment of mesocrystals are also formed judging from the voided Sierpinski polyhedrons observed. Furthermore, the interior nanowire architecture of these mesocrystals can be kinetically controlled by careful variation of growth conditions. Owing to high specific surface area and improved conductivity, the rGO-Cu(2)O mesocrystals achieved a higher sensitivity toward NO(2) at room temperature, surpassing the performance of standalone systems of Cu(2)O nanowires networks and rGO sheets. The unique characteristics of rGO-Cu(2)O mesocrystal point to its promising applications in ultrasensitive environmental sensors.

Ceria nanoparticles are one of the key abrasive materials for chemical-mechanical planarization of advanced integrated circuits. However, ceria nanoparticles synthesized by existing techniques are irregularly faceted, and they scratch the silicon wafers and increase defect concentrations. We developed an approach for large-scale synthesis of single-crystal ceria nanospheres that can reduce the polishing defects by 80% and increase the silica removal rate by 50%, facilitating precise and reliable mass-manufacturing of chips for nanoelectronics. We doped the ceria system with titanium, using flame temperatures that facilitate crystallization of the ceria yet retain the titania in a molten state. In conjunction with molecular dynamics simulation, we show that under these conditions, the inner ceria core evolves in a single-crystal spherical shape without faceting, because throughout the crystallization it is completely encapsulated by a molten 1- to 2-nanometer shell of titania that, in liquid state, minimizes the surface energy. The principle demonstrated here could be applied to other oxide systems.

Purpose The purpose of this paper is to address the increasingly important question of supply chain design for global operations. With the rise of off‐shore sourcing and the simultaneous need for improved responsiveness to customer demand, the choice of supply chain strategy is critical. Design/methodology/approach The paper draws its conclusions from case‐based research supported by survey data. Findings The paper provides evidence that the choice of supply chain strategy should be based upon a careful analysis of the demand/supply characteristics of the various product/markets served by a company. It presents the basis for a taxonomy of appropriate supply chain strategies. Research limitations/implications The case studies and empirical research reported in this paper are specific to the clothing manufacturing and fashion industries and there would be benefit in extending the research into other sectors. Practical implications Given the increasing trend to out‐sourcing and off‐shore sourcing, the choice of supply chain strategy is of some significance and clearly impacts competitive performance. Originality/value Whilst there is a growing recognition of the need to match the supply chain to the market, there is still limited research into what criteria should be utilised to aid the choice of supply chain strategy. This paper attempts to extend our understanding of the issues.

Supply chain vulnerability has become a fashionable area of management research. The purpose of this paper is to provide a critique of the extant canon and to review of the positioning of research in the field, together with literature drawn from several relevant and overlapping fields of research and practice. The aim is to foster a more explicit understanding of the relationships between supply chain vulnerability, risk and supply chain management, and in turn their relevance to related fields such as corporate governance, business continuity management, security and emergency planning. The ultimate objective is to clarify the agenda for further research. The paper begins with an examination of the concept of a “supply chain” and the scope and nature of supply chain management (SCM), then the fusion of SCM with the many and varied interpretations of “risk” and its faltering relationship to risk management. It is argued that attitudes to risk and approaches to risk management vary greatly within SCM and between related disciplines. It is concluded that although more work is needed within the SCM discipline, the issue of supply chain risk and vulnerability should not be addressed solely from a functional SCM perspective. Supply chain vulnerability is a concern for many other managerial disciplines. Research agendas should therefore strive to inform and support the needs of all those with a legitimate interest in supply chain risk and vulnerability management.

The importance of the mechanical role of collagen in bone is becoming increasingly more clear as evidence mounts on the detrimental effects of altered collagen on the mechanical properties of bone. We previously examined a set of mechanical properties (material stiffness, strength, and toughness) of human femoral bone (ages 35-92) and found that a gradual deterioration in these properties occurs with age. The present study examines the collagen of the same specimens and relates the collagen properties to the mechanical ones. In the collagen we measured the concentration of stable mature crosslinks, the shrinkage temperature, and the rate of contraction during isometric heating. The changes in the concentration of mature (pyridinium and deoxypyridinium) crosslinks showed no clear relationship to age nor did they correlate with the mechanical properties. The shrinkage temperature declined with age and correlated with a bone's toughness. The maximum rate of contraction was strongly correlated with three different measures of tissue toughness, but much less to stiffness and strength. Our results reinforce speculation regarding the toughening role of collagen in bone mechanics and suggest that the fragility of aging bone may be related to collagen changes.

Characterizing genetic diversity in Africa is a crucial step for most analyses reconstructing the evolutionary history of anatomically modern humans. However, historic migrations from Eurasia into Africa have affected many contemporary populations, confounding inferences. Here, we present a 12.5× coverage ancient genome of an Ethiopian male ("Mota") who lived approximately 4500 years ago. We use this genome to demonstrate that the Eurasian backflow into Africa came from a population closely related to Early Neolithic farmers, who had colonized Europe 4000 years earlier. The extent of this backflow was much greater than previously reported, reaching all the way to Central, West, and Southern Africa, affecting even populations such as Yoruba and Mbuti, previously thought to be relatively unadmixed, who harbor 6 to 7% Eurasian ancestry.

Ceria is an important component in three-way catalysts for the treatment of automobile exhaust gases owing to its ability to store and release oxygen, a property known as the oxygen storage capacity. Much effort has been focused on increasing the OSC of ceria, and one avenue of exploration is the ability to fabricate CeO(2)-based catalysts, which expose reactive surfaces. Here we show how models for a polycrystalline CeO(2) thin film, which expose the (111), (110), and dipolar (100) surfaces, can be synthesized. This is achieved by supporting the CeO(2) thin film on an yttrium-stabilized zirconia substrate using a simulated amorphization and recrystallization strategy. In particular, the methodology generates models which reveal the atomistic structures present on the surface of the reactive faces and provides details of the grain-boundary structures, defects (vacancies, substitutionals, and clustering), and epitaxial relationships. Such models are an important first step in understanding the active sites at the surface of a catalytic material.

Ionic liquids have been considered for their potential applications within the nuclear fuel cycle. If ionic liquids are to be successful in their application as solvents for highly radioactive materials in any future process, there will be a requirement for them to be robust to high radiation doses. A preliminary assessment of the radiation stability of 1,3-dialkylimidazolium cation based ionic liquids containing nitrate and chloride anions has been performed. The results of radiolysis studies are reported, in which the samples were exposed to alpha radiation from a tandem Van der Graaff generator, beta radiation from a linear accelerator and gamma radiation from cobalt 60 sources. These results suggest that their stability is similar to that of benzene and that they are much more stable than mixtures of tributylphosphate and odourless kerosene under similar irradiation conditions. The radiolysis of 1,3-dialkylimidazolium cation based ionic liquids reflects their combination of the properties of a salt, an alkane and an aromatic. They appear to be relatively radiation resistant and there is certainly no major decomposition of the organic component.

This paper introduces the concept and principles of hyperspectral imaging (HSI) and it briefly outlines how the defence and homeland security sectors can benefit from the application of this extremely versatile technology. This paper outlines the pros and cons of the various HSI system configurations, with particular emphasis on two of the most commonly deployed spectrograph techniques, namely, the dispersive system and the narrow-band tuning filter system. It describes how HSI can be utilized for target acquisition particularly when there is no a priori knowledge of the target, and then shows how it can be used for the recognition and tracking of targets with desired or known signature characteristics. The paper also briefly mentions the possibility of remote HSI being used for recognizing a human's physiological state such as that induced by stress or anxiety. Real experimental data collected during the course of our research have been utilized throughout this paper to help understand the versatility and effectiveness of HSI technology.

The influence of water on the redox properties of ceria is pivotal to its widespread exploitation spanning a variety of applications. Ab initio simulation techniques based on DFT-GGA+U are used to investigate the water–ceria system including associative (H2O) and dissociative (−OH) adsorption/desorption of water and the formation of oxygen vacancies in the presence of water vapor on the stoichiometric and reduced low index surfaces of ceria at different water coverages. Our calculations address the controversy concerning the adsorption of water on the CeO2{111}, and new results are reported for the CeO2{110} and {100} surfaces. The simulations reveal strong water coverage dependence for dissociatively (−OH) adsorbed water on stoichiometric surfaces which becomes progressively destabilized at high coverage, while associative (H2O) adsorption depends weakly on the coverage due to weaker interactions between the adsorbed molecules. Analysis of the adsorption geometries suggests that the surface cerium atom coordination controls the strong adhesion of water as the average distance Ce–OW is always 10% greater than the Ce–O distance in the bulk, while the hydrogen bonding network dictates the orientation of the molecules. The adsorption energy is predicted to increase on reduced surfaces because oxygen vacancies act as active sites for water dissociation. Crucially, by calculating the heat of reduction of dry and wet surfaces, we also show that water promotes further reduction of ceria surfaces and is therefore central to its redox chemistry. Finally, we show how these simulation approaches can be used to evaluate water desorption as a function of temperature and pressure which accords well with experimental data for CeO2{111}. We predict desorption temperatures (TD) for CeO2{110} and CeO2{100} surfaces, where experimental data are not yet available. Such an understanding will help experiment interpret the complex surface/interface redox processes of ceria, which will, inevitably, include water.

The historical chronologies for dynastic Egypt are based on reign lengths inferred from written and archaeological evidence. These floating chronologies are linked to the absolute calendar by a few ancient astronomical observations, which remain a source of debate. We used 211 radiocarbon measurements made on samples from short-lived plants, together with a Bayesian model incorporating historical information on reign lengths, to produce a chronology for dynastic Egypt. A small offset (19 radiocarbon years older) in radiocarbon levels in the Nile Valley is probably a growing-season effect. Our radiocarbon data indicate that the New Kingdom started between 1570 and 1544 B.C.E., and the reign of Djoser in the Old Kingdom started between 2691 and 2625 B.C.E.; both cases are earlier than some previous historical estimates.

A compact wearable antenna with a novel miniaturized electromagnetic bandgap (EBG) structure at 2.4 GHz for medical application is presented in this letter. The design demonstrates a robust, compact, and low-profile solution to meet the requirements of wearable applications. The EBG structure reduces the back radiation and the impact of frequency detuning due to the high losses of human body. In addition, the structure improves the front-to-back ratio (FBR) by 15.5 dB. The proposed compact antenna with dimensions of 46 × 46 × 2.4 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> yields an impedance bandwidth of 27% (2.17-2.83 GHz), with a gain enhancement of 7.8 dBi and more than 95% reduction in the specific absorption rate. Therefore, the antenna is a promising candidate for integration into wearable devices applied in various domains, specifically biomedical technology.

The recent advances in mobile technologies have resulted in Internet of Things (IoT)-enabled devices becoming more pervasive and integrated into our daily lives. The security challenges that need to be overcome mainly stem from the open nature of a wireless medium, such as a Wi-Fi network. An impersonation attack is an attack in which an adversary is disguised as a legitimate party in a system or communications protocol. The connected devices are pervasive, generating high-dimensional data on a large scale, which complicates simultaneous detections. Feature learning, however, can circumvent the potential problems that could be caused by the large-volume nature of network data. This paper thus proposes a novel deep-feature extraction and selection (D-FES), which combines stacked feature extraction and weighted feature selection. The stacked autoencoding is capable of providing representations that are more meaningful by reconstructing the relevant information from its raw inputs. We then combine this with modified weighted feature selection inspired by an existing shallow-structured machine learner. We finally demonstrate the ability of the condensed set of features to reduce the bias of a machine learner model as well as the computational complexity. Our experimental results on a well-referenced Wi-Fi network benchmark data set, namely, the Aegean Wi-Fi Intrusion data set, prove the usefulness and the utility of the proposed D-FES by achieving a detection accuracy of 99.918% and a false alarm rate of 0.012%, which is the most accurate detection of impersonation attacks reported in the literature.

In 1974, Heinz von Foerster articulated the distinction between a first‐ and second‐order cybernetics, as, respectively, the cybernetics of observed systems and the cybernetics of observing systems. Von Foerster's distinction, together with his own work on the epistemology of the observer, has been enormously influential on the work of a later generation of cyberneticians. It has provided an architecture for the discipline of cybernetics, one that, in true cybernetic spirit, provides order where previously there was variety and disorder. It has provided a foundation for the research programme that is second‐order cybernetics. However, as von Foerster himself makes clear, the distinction he articulated was imminent right from the outset in the thinking of the early cyberneticians, before, even, the name of their discipline had been coined. In this paper, the author gives a brief account of the developments in cybernetics that lead to von Foerster's making his distinction. As is the way of such narratives, it is but one perspective on a complex series of events. Not only is this account a personal perspective, it also includes some recollections of events that were observed and participated in at first hand.

Over the last five years there has been an increase in the frequency and diversity of network attacks. This holds true, as more and more organizations admit compromises on a daily basis. Many misuse and anomaly based intrusion detection systems (IDSs) that rely on either signatures, supervised or statistical methods have been proposed in the literature, but their trustworthiness is debatable. Moreover, as this paper uncovers, the current IDSs are based on obsolete attack classes that do not reflect the current attack trends. For these reasons, this paper provides a comprehensive overview of unsupervised and hybrid methods for intrusion detection, discussing their potential in the domain. We also present and highlight the importance of feature engineering techniques that have been proposed for intrusion detection. Furthermore, we discuss that current IDSs should evolve from simple detection to correlation and attribution. We descant how IDS data could be used to reconstruct and correlate attacks to identify attackers, with the use of advanced data analytics techniques. Finally, we argue how the present IDS attack classes can be extended to match the modern attacks and propose three new classes regarding the outgoing network communication.

Breast calcifications are often the only mammographic features indicating the presence of a cancerous lesion. Calcium oxalate (type I) may be found in and around benign lesions, however calcium hydroxyapatite (type II) is usually found within proliferative lesions, which can include both benign and malignant pathologies. However, the composition of type II calcifications has been demonstrated to vary between benign and malignant proliferative lesions, and could be an indicator for the possible disease state. Raman spectroscopy has previously been demonstrated as a powerful tool for non-destructive analysis of tissues, utilising laser light to probe chemical composition. Raman spectroscopy is traditionally a surface technique. However, we have recently developed methods that permit its application for obtaining sample composition to clinically relevant depths of many mm. We report the first demonstration of spatially offset Raman spectroscopy (SORS) for potential in vivo breast analysis. This study evaluates the possibility of utilising SORS for measuring calcification composition through varying thicknesses of tissues (2 to 10 mm), which is about one to two orders of magnitude deeper than has been possible with conventional Raman approaches. SORS can be used to distinguish non-invasively between calcification types I and II (and carbonate substitution of phosphate in calcium hydroxyapatite) within tissue of up to 10 mm deep. This result secures the first step in taking this technique forward for clinical applications seeking to use Raman spectroscopy as an adjunct to mammography for early diagnosis of breast cancer, by utilising both soft tissue and calcification signals. Non-invasive elucidation of calcification composition, and hence type, associated with benign or malignant lesions, could eliminate the requirement for biopsy in many patients.

This paper presents a novel estimation method for fast initial coarse alignment of a ship's strapdown inertial attitude reference system using only inertial measurement unit (IMU) measurements for quasi-static alignment and IMU measurements with GPS aiding for moving-base alignment. Unlike several current techniques, the presented estimation method is effective with any initial attitude error. The estimator is based on the decomposition of the attitude quaternion into separate Earth motion, inertial rate, and alignment quaternions. The alignment quaternion is estimated using a minimum variance fit between loci of body- and navigation-frame velocity vectors using solutions to Wahba's problem. One set of vectors is derived from time integrals of measured vehicle motions, and the second set is derived from Earth motion and GPS data (when moving). For the case of quasi-static alignment, an algebraic expression for the covariance of the attitude estimate as a function of the variance of navigation-frame velocity disturbances is developed. It is shown that, by averaging and interleaving the velocity vectors, the resulting attitude estimate is improved over sequential sampling techniques. It is further shown, for a maneuvering vessel, that a continuous estimate of the attitude error covariance can be generated from the IMU data. This latter feature allows direct initialization of a follow-on fine-alignment stochastic estimator's covariance matrix. Results are presented for quasi-static alignment using inertial sensors only and for full in-motion alignment using navigation-frame GPS velocity and position aiding.

An analysis is presented of a thin cylindrical-rectangular microstrip patch antenna. After obtaining the electric field under the curved patch and the resonant frequencies using the cavity model, the far-field is found by considering the equivalent magnetic current radiating in the presence of a cylindrical surface. The input impedance and the total Q-factor are then calculated. Numerical and graphical results are presented to illustrate the effect of curvature on the characteristics of the TM/sub 10/ and TM/sub 01/ modes.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Wide range of techniques used to obtain fundamental optical and optoelectronic properties of CZTS single crystals grown by vapour transport.

We calculate, using simulated amorphisation and recrystallisation (A&R), that ceria (CeO2) nanoparticles, about 8 nm in diameter, comprise a high concentration of labile surface oxygen species, which we suggest will help promote the oxidation of CO to CO2. In particular, the ceria nanoparticle contains a high proportion of reactive {100} surfaces, surface steps and corner sites. When reduced to CeO1.95, the associated Ce3+ species and oxygen vacancies decorate step, corner and {100} sites in addition to plateau positions on {111}. The energetics of CO oxidation to CO2, catalysed by a ceria nanoparticle, is calculated to be lower compared with CO oxidation associated with the lowest energy surface (i.e. CeO2(111)) of the corresponding 'bulk' material. Our calculated morphologies for the ceria nanoparticles are in accord with experiment.