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This book provides an introduction to the mathematical and algorithmic foundations of data science, including machine learning, high-dimensional geometry, and analysis of large networks. Topics include the counterintuitive nature of data in high dimensions, important linear algebraic techniques such as singular value decomposition, the theory of random walks and Markov chains, the fundamentals of and important algorithms for machine learning, algorithms and analysis for clustering, probabilistic models for large networks, representation learning including topic modelling and non-negative matrix factorization, wavelets and compressed sensing. Important probabilistic techniques are developed including the law of large numbers, tail inequalities, analysis of random projections, generalization guarantees in machine learning, and moment methods for analysis of phase transitions in large random graphs. Additionally, important structural and complexity measures are discussed such as matrix norms and VC-dimension. This book is suitable for both undergraduate and graduate courses in the design and analysis of algorithms for data.
In this paper, we study a large multi-server loss model under the SQ(d) routeing scheme when the service time distributions are general with finite mean. Previous works have addressed the exponential service time case when the number of servers goes to infinity, giving rise to a mean field model. The fixed point of the limiting mean field equations (MFEs) was seen to be insensitive to the service time distribution in simulations, but no proof was available. While insensitivity is well known for loss systems, the models, even with state-dependent inputs, belong to the class of linear Markov models. In the context of SQ(d) routeing, the resulting model belongs to the class of nonlinear Markov processes (processes whose generator itself depends on the distribution) for which traditional arguments do not directly apply. Showing insensitivity to the general service time distributions has thus remained an open problem. Obtaining the MFEs in this case poses a challenge due to the resulting Markov description of the system being in positive orthant as opposed to a finite chain in the exponential case. In this paper, we first obtain the MFEs and then show that the MFEs have a unique fixed point that coincides with the fixed point in the exponential case, thus establishing insensitivity. The approach is via a measure-valued Markov process representation and the martingale problem to establish the mean field limit.
This article argues that the late 1940s in India should no longer be reduced to the twin events of partition and independence. A generalized political crisis unsettled, for a brief period, the structures of social and economic power, and not just intercommunity relations and the constitution of the state. These years were thus, among other things, a catalytic moment for the definition of ‘labour’ as both a political category and a parameter of post-colonial politics: processes dating back to the First World War, at least, were consolidated, under pressure from this crisis, into a new labour regime that has withstood political pressure for almost seven decades. The article offers an analysis of the almost-forgotten post-war strike movement, which was nevertheless unprecedented in its social and geographical spread. The movement elicited both repressive and reformist responses: the extraordinary level of emergency powers applied to suppress it are, therefore, as much examined as the series of momentous legislative and institutional changes of the late 1940s. In conclusion, the long-term consequences of this cycle of strike–reform–repression for India's post-colonial labour regime are adumbrated. A strongly etatist, potentially authoritarian, regime of industrial relations, it is argued, was checked by an enduring political trade union pluralism. At the same time, divisions within India's working classes were deepened and consolidated as labour law and social legislation sealed off the comparatively small ‘core workforces’ of public sector and large-scale industrial enterprises from the majority of workers in what would soon be called the ‘informal economy’.
We sought to establish the impact on vaccine uptake of sending out a single appointment letter inviting patients to attend a vaccine clinic.
Coeliac disease is associated with splenic dysfunction and so patients with coeliac disease are at a higher risk of overwhelming infection. Additional vaccinations are recommended for these individuals to provide additional protection against infection.
We retrospectively identified 54 patients with diagnosed coeliac disease, and all vaccines previously received by these patients. By comparing this to the Green Book [Department of Health (2013) Immunisation of individuals with underlying medical conditions: the green book, chapter 7, London: Department of Health. Retrieved 26 February 2019 from https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/566853/Green_Book_Chapter7.pdf], we determined the patients who were due vaccinations and the specific vaccines they were due. An invitation letter was then sent out to patients requiring further vaccinations and vaccine uptake for these patients was re-audited six months later.
Our results show a mild increase in the total uptake of vaccines six months after the letter was sent out, from 38.6% to 49.2%.
Semiconducting nanostructures such as nanowires (NWs) have been used as building blocks for various types of sensors, energy storage and generation devices, electronic devices and for new manufacturing methods involving printed NWs. The response of these sensing/energy/electronic components and the new fabrication methods depends very much on the quality of NWs and for this reason it is important to understand the growth mechanism of 1D semiconducting nanostructures. This is also important to understand the compatibility of NW growth steps and tools used in the process with these unconventional substrates such as plastic that are used in flexible and large area electronics. Therefore, this Element presents at length discussion about the growth mechanisms, growth conditions and the tools used for the synthesis of NWs. Although NWs from Si, ZnO and carbon nanotubes (CNTs) are included, the discussion is generic and relevant to several other types of NWs as well as heterostructures.
The Richtmyer–Meshkov (RM) instability is numerically investigated on an unperturbed interface subjected to a diffracted convergent shock created by diffracting an initially cylindrical shock over a rigid cylinder. Four gas interfaces are considered with Atwood number ranging from
to 0.67. Results indicate that the diffracted convergent shock increases its strength gradually and reduces its amplitude quickly when it propagates towards the convergence centre. After the strike of the diffracted convergent shock, the initially unperturbed interface deforms with a bulge structure at the centre and two interface steps at both sides, which can be ascribed to the non-uniformity of the pressure distribution behind the diffracted convergent shock. With the decrease of Atwood number, the bulge structure becomes more pronounced. Quantitatively, the interface amplitude experiences a fast but short growing stage and then enters a linear stage. A good collapse of the dimensionless amplitude is found for all cases, which indicates a weak dependence of the growth rate on Atwood number in the deformed shock-induced RM instability. Then the impulsive theory is modified by eliminating the Atwood number and considering the geometry convergence, which well predicts the amplitude growth for the deformed shock-induced RM instability. Finally, the underlying mechanism is decoupled into three parts, and it is found that both the impulsive pressure perturbation and the geometry convergence promote the growth of interface perturbation while the continuous pressure perturbation inhibits the growth. As the Atwood number decreases, the impulsive perturbation plays an increasingly important role, which suggests that the impulsive perturbation dominates the deformed shock-induced RM instability at the linear stage.
Bottom-up assembly of nanomaterials using solution-processed methods is ideally suited for use in fabrication of large-area optoelectronic devices. Tailorable visible and near-infrared absorption in shaped nanostructured noble metals is strongly influenced by localized plasmon resonance effects. Obtaining sharp and selective absorption with solution-processed methods is a challenge and requires suitable control on the growth kinetics, which ultimately results in appropriate size and morphology of the final product. In this work, a photo-assisted multigenerational growth process for synthesis of silver nanotriangle ink with narrow linewidth absorbance is developed. This technique combines photochemical and seed-mediated growth approaches. The resulting ink exhibits a sharp absorption at 700 nm with full width at half maximum of ∼170 nm, verified by absorption as well as dynamic light scattering, transmission electron microscopy, and field emission scanning electron microscopy measurements. Numerical modeling using finite-difference time-domain calculations yields a close match with observed absorption and is used to examine electric field distribution and enhancement factor resonating at 720 nm. The synthesis technique is potentially useable for production of highly selective absorbers in solution phase.
Filariasis is one of the major public health concerns in India. Approximately 600 million people spread across 250 districts of India are at risk of filariasis. To predict this disease, a pilot scale study was carried out in 30 villages of Karimnagar district of Telangana from 2004 to 2007 to collect epidemiological and socio-economic data. The collected data are analysed by employing various machine learning techniques such as Naïve Bayes (NB), logistic model tree, probabilistic neural network, J48 (C4.5), classification and regression tree, JRip and gradient boosting machine. The performances of these algorithms are reported using sensitivity, specificity, accuracy and area under ROC curve (AUC). Among all employed classification methods, NB yielded the best AUC of 64% and was equally statistically significant with the rest of the classifiers. Similarly, the J48 algorithm generated 23 decision rules that help in developing an early warning system to implement better prevention and control efforts in the management of filariasis.
It is known that 12C beam transmission through the accelerator decreases at high beam currents. This effect depends on machine design and varies across different types of AMS instruments. For beam currents of about 100 μA, the effect is small on the 500 kV tandem CAMS unit, whereas beam saturation is observed for similar high beam currents on the 250 kV SSAMS unit. While this effect is very evident for high 12C beam currents, we have also observed that even the 13C beam is found to suffer modest transmission loss with beam current. As a result, the 13C/12C ratio does not remain constant with beam current. By correcting for the effects of 12C beam saturation and decreased 13C transmission, we have obtained online δ13C values that are more accurate and precise at moderately high beam currents for SSAMS.
Film technology has become an increasingly prominent component of theatre design. In the practice of Robert Wilson and Robert Lepage it may support what has been described as a ‘pizza style’ of presentation, in which disparate techniques and modes of presentation are used to disturb conventional ideas of narrative, context, and textual authority, while in the work of Motionhouse it creates a language of dance as circus. The longstanding collaboration between film designer Ravi Deepres and choreographer Wayne McGregor presents an alternative model, at once highly composed as narrative and based on meticulous research into textual evidence. In this interview with David Roberts, Deepres charts the evolution of his work with McGregor up to their award-winning Woolf Works, showing how a genuinely collaborative artistic process and attention to the graphic possibilities of different film technologies have transformed our understanding of the role of design in devised performance. Ravi Deepres is Professor of Moving Image and Photography at Birmingham City University. For the past nineteen years he has designed shows in collaboration with choreographer Wayne McGregor. Their most recent success, Woolf Works, won the Olivier Award for Best New Dance Production and re-opened at La Scala Milan in April 2019. David Roberts is Professor of English at Birmingham City University. His recent publications include George Farquhar: A Migrant Life Reversed (Bloomsbury, 2018), and he is currently working on a new edition of Congreve's The Way of the World.
The article explores the history of the Employees’ State Insurance Act of 1948 (ESI), a law enacted in the first year of Indian independence. Global trends in social policy had influenced debates on a social insurance for Indian workers since the 1920s. Transformations of Indian industry, World War II, the post-war crisis, and the emerging economic policy of the postcolonial State then created conditions for legislation. Just as the international welfare discourse, Indian contributions included, converged on social welfare as a universal citizen right, the regulatory content of the health insurance scheme devised for India diverged from this normative consensus: the ESI Act remained strictly employment-based, contributed to an emerging structure of graded entitlements, and to the hardening of boundaries between what would later be called “formal” and “informal” labour. Simultaneously, it also generated horizons of expectation that continue to inform labour struggles.
A rigorous analysis of yield strength of pure iron over a wide grain size scale, using an extensive compilation of experimental data, indicates that the common Hall–Petch relationship is not obeyed with large deviations at the extremes of grain size. The author proposes here a phenomenological exponential function to represent the grain size effect on strength over multiple length scales. It is shown that the exponential function describes the grain size dependence of strength remarkably well, on the basis of a large set of experimental data for pure Fe. A nonlinear regression analysis indicated that the function provided a very high degree of correlation of data. The validity of the function is also supported by its conformation to physical boundary conditions at the extremes of grain size, that is, by asymptotically reaching the limiting stress for dislocation nucleation at infinitesimal grain size, and, the strength of single crystal at infinite grain size. The exponential form is a significant improvement over the Hall–Petch relationship and may be used as a guide to develop a reliable theory of grain size strengthening of iron.
We present large-eddy simulation (LES) of flow past different airfoils with
, based on the free-stream velocity and airfoil chord length, ranging from
. To avoid the challenging resolution requirements of the near-wall region, we develop a virtual wall model in generalized curvilinear coordinates and incorporate the non-equilibrium effects via proper treatment of the momentum equations. It is demonstrated that the wall model dynamically captures the instantaneous skin-friction vector field on arbitrary curved surfaces at the resolved scale. By combining the present wall model with the stretched-vortex subgrid-scale model, we apply the wall-modelled LES approach to three different airfoil cases, spanning different geometrical parameters, different attack angles and low to high
. The numerical results are verified with direct numerical simulation (DNS) at low
, and validated with experiment data at higher
, including typical aerodynamic properties such as pressure coefficient distributions, velocity components and also more challenging measurements such as skin-friction coefficient and Reynolds stresses. All comparisons show reasonable agreement, providing a measure of validity that enables us to further probe simulation results into aspects of flow physics that are not available from experiments. Two techniques to quantify hitherto unexplored physics of flows past airfoils are employed: one is the construction of the anisotropy invariant map, and the second is skin-friction portraits with emphasis on flow transition and unsteady separation along the airfoil surface. The anisotropy maps for all three
cases, show clearly that a portion of the flow field is aligned along the axisymmetric expansion line, corresponding to the turbulent boundary layer log-law behaviour and the appearance of turbulent transition. The instantaneous skin-friction portraits reveal a monotonic shrinking of the near wall structure scale. At
, the interaction between the primary separation bubble and the secondary separation bubble contributes to turbulent transition, similar to the case of flow past a cylinder. At higher
, the primary separation breaks into several small separation bubbles. At even higher
, near the turbulent separation, the skin-friction lines show small-scale reversal flows that are similar to those observed in DNS of the flat plate turbulent separation. A notable feature of turbulent separation in flow past an airfoil is the appearance of turbulence structures and small-scale reversal flows in the spanwise direction due to the vortex shedding behaviour.
Biatrial drainage of the right superior caval vein is an extremely rare cardiac anomaly that generally presents in childhood. We present a case of anomalous connection of the right superior caval vein with superior sinus venosus atrial septal defect and partial anomalous pulmonary venous return in a 5-month-old male presenting with unexplained cyanosis and hypoxia.
Nuclear power epitomizes the unusual combination of quantitative expansion, rapid upgrading of technological, managerial and regulatory capabilities, growing competitiveness, burgeoning global involvement, and also potential economic, environmental and security risk surrounding Chinese innovative efforts. A combination of domestic upgrading and international cooperation has delivered a rapid buildup of capabilities in design, construction, operation, equipment manufacture and regulatory capacity alongside ambitious nuclear investment. Surprising features of China’s nuclear buildup include the centrality of enterprise initiative in an industry seemingly dominated by government controls; the strength of nuclear safety oversight in an economy with limited institutional capacity for prudential regulation; and China’s sudden and unexpected emergence as a major player in the global market for nuclear power installations – an apparent instance of Christensen’s theory of “new market disruption.” Despite its impressive advance, China’s nuclear sector faces multiple challenges arising from institutional limitations, corruption, conflicts between supply-chain inadequacies and pressure for import substitution, and an ironic confluence of overseas market success with a sudden erosion in the financial underpinnings of nuclear electricity production in China itself.
Pharmacological treatments targeting the neuroendocrine stress response may hold special promise in secondary prevention of posttraumatic stress disorder (PTSD). However, findings from clinical trials have been inconsistent and the efficacy of specific drugs, their temporal window of efficacy, effective doses and the characteristics of likely treatment responders remain unclear.
Using an experimental human model of distressing involuntary memory formation, we compare the effects of two drugs that have theoretical or empirical support as secondary preventive agents in PTSD. Eighty-eight healthy women (average age: 23.5 years) received oral propranolol (80 mg), hydrocortisone (30 mg), or matched placebo immediately after viewing a ‘trauma film’. They then completed daily, time-stamped intrusion diaries for 1 week, at the end of which, voluntary memory was tested.
While neither drug affected voluntary memory for the trauma narrative, propranolol treatment was associated with 42% fewer, and hydrocortisone with 55% fewer intrusions across the week, relative to placebo. Additionally, propranolol reduced general trauma-like symptoms, and post-drug cortisol levels were negatively correlated with intrusion frequency in the hydrocortisone group.
Overall, this study shows substantial reductions in intrusive memories and preserved voluntary narrative-declarative memory following either propranolol or hydrocortisone in an experimental model of psychological trauma. As such, despite some inconsistencies in clinical trials, our findings support continued investigation of propranolol and hydrocortisone as secondary preventive agents for re-experiencing symptoms of PTSD. The findings also suggest that it is critical for future research to identify the conditions governing the preventive efficacy of these drugs in PTSD.
Lithium substituted magnesium ferrites (LixMg1-xFe2O4, where x = 0.1 to 0.5) were synthesized by solid state reaction method. Various characterization techniques viz. X - Ray Diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometry (VSM) and fourier transform infrared spectroscopy (FTIR) were used to study the effect of lithium substitution. Differences in particle size, crystallinity and magnetic parameters of the ferrites synthesized with difference in composition were observed. XRD patterns of the synthesized samples confirmed phase purity and showed that the lattice parameter decreases with increase in Li content in magnesium ferrite. Decrease in coercivity with increase in lithium concentration was observed from magnetic analysis (VSM). Through FTIR, it was observed that Li+ ions occupy B – sites. FTIR spectrum peaks obtained in the region 1620 – 1670 cm-1 supported water molecule dissociation. It is the required characteristic of the lithium substituted magnesium ferrite to be used in various applications like humidity sensor and hydroelectric cell.
Low genetic diversity acts as a major bottleneck in garden pea breeding, and diverse parents are required to generate new genetic material. The diversity of parents utilized in hybridization programme was ascertained following simple sequence repeats (SSR) markers. Thirty-six homozygous F7 progenies were isolated from three intervarietal crosses through shuttle breeding programme over a period of 6 years (2009–2014). Two experiments were conducted for two consecutive years 2014/15 and 2015/16, for evaluating the agronomic performance of progenies along with four commercial control cultivars. Analysis of variance (ANOVA) revealed that genotype, growing year and their interaction had significant effects on most of the traits. Line ‘DPP-SP-6’ recorded significantly higher pod yield/plant in comparison to all other genotypes in 2014/15, 2015/16 and for pooled over years. In addition, ‘DPP-SP-22’, ‘DPP-SP-7’ and ‘DPP-SP-17’ also performed statistically at par with best-performing check ‘Pb-89’ during both the years. These superior lines, in general, showed better pod filling, green pod colour, high shelling, sweetness and resistance to powdery mildew disease. These superior progenies could act as an alternative to the popular check varieties after their exhaustive evaluation over environments.