bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamic Problems of Interplanetary Flight
Authors: Lawden Derek F.
Published: July 2016

The solution to the general problem of transferring a rocket between two terminals in space with minimum fuel expenditure is explained and the results obtained when application is made to a number of particular problems of space navigation are described. The mathematical techniques which may usefully be employed in the calculation of optimum rocket trajectories are exemplified by a method of solving the problem of obtaining maximum range from a rocket missile over the Earth's surface.
Compressible Subsonic Flow in Two-dimensional Channels
Authors: Woods L. C.
Published: July 2016

Equations for the calculation of the subsonic flow of an inviscid fluid through given two-dimensional channels (the “ direct” problem), and for the design (the “ indirect” problem) of such channels are derived. The method is based on conformal mapping, and in the special case of channels with walls made from a number of straight sections, or with wall pressure prescribed as step-functions, yields the same results as the well-known Schwarz-Christoffel mapping theorem technique. However, it is more general than this latter method, since it is capable of dealing with curved walls or continuously varying wall pressures. The compressibility of the fluid is allowed for only approximately, the ideal gas being replaced by a Kàrmàn-Tsien tangent gas.

In Part II the theory is applied to various problems of aeronautical interest, perhaps the most important of which is to the setting of “ streamlined ” walls about a symmetrical aerofoil placed in the centre of the channel.
Photoelastic Investigation in Connection with the Fatigue Strength of Bolted Joints
Authors: Jessop H. T. , Snell C. , Holister G. S.
Published: July 2016

The elastic stress distribution around a circular hole in a flat bar under simple tension, when the hole is filled by a push-fit pin, was investigated photoelastically. Over a range of values of the ratio of hole diameter to width of bar, and for pins of differing Young's moduli, the effect of the pin was sensibly the same, namely, to reduce the maximum tension on the hole boundary by about 15 per cent, as compared with that in the unfilled hole.

The maximum shear stress on the boundary was unaltered.
Compressible Subsonic Flow in Two-dimensional Channels
Authors: Woods L. C.
Published: July 2016

The theory developed in Part I is applied to a number of problems of aeronautical interest, the most important of which is to the setting of “ streamline “ walls about a symmetrical aerofoil placed in the centre of a channel. It is shown how the position of the streamline wall can be deduced from the (experimentally determined) position of a constant pressure wall. This theory is applicable to symmetrical aerofoils of any given shape, and makes allowance for the presence of the aerofoil's wake. To illustrate the theory, and to test it by an extreme example, the flow is calculated about a circular cylinder, with a diameter about half the tunnel height, for both straight and constant pressure walls. The solid blockage is calculated in each case and compared with the standard first order theory. For this extreme example the standard theory fails badly for straight walls, but is reasonably accurate for constant pressure walls.
Stabilisation of the Aeroplane in Symmetric Flight at Zero or Very Small Air Speeds
Authors: Coleman W. S.
Published: July 2016

The possible use of jet thrust as a source of lift, either by deflection of the force from the normal propulsion axis, or by some other means, raises a new stability problem under conditions of hovering flight and flight at speeds for which the aerodynamic damping becomes insignificant. At the same time, despite the small dynamic pressure, the direct air loads cannot be neglected, for, due to the very large positive or negative incidences peculiar to the motion, the associated coefficients are of a compensatingly high order. Consequently, the problem retains an aerodynamic element, but is principally one of automatic stabilisation, amenable to treatment by ordinary mechanical or electrical circuit theory. The investigation has been restricted to the longitudinal-symmetric motion with virtually the only workable form of automatic control, namely, one responsive to the angular displacement and velocity in pitch, but these conditions undoubtedly embrace all the essentials of any practical application, e.g. in take-off and landing by the new technique. The solution to the stability in a gust, or in a succession of disturbances, may then be easily obtained in closed analytical form, but the more general case of unsteady motion, when the displacements are no longer purely oscillatory, necessitates, in part, the use of step-by-step integration. This arises from the added complexity of the aerodynamic terms, due to the appearance of significant changes of incidence, and to the very large and variable values of the resistance derivatives at the angles involved, so that, in the present state of knowledge, the forces determining the motion cannot be expressed functionally. The labour which such calculations entail may be considerably shortened, however, by the application of a procedure based on mean deviations, but it is also found that the conclusions to be drawn from the hovering case remain valid in a number of important respects for the general problem. This feature is demonstrated in the discussion at the end of the paper on a number of examples designed to illustrate the characteristics of the automatic control and the conditions necessary for stability in a variety of circumstances, both when the aircraft is hovering and when its displacement increases continuously with time.
Some Exploratory Three-Dimensional Jet-Flap Experiments
Authors: Williams J. , Alexander A. J.
Published: July 2016

This paper describes a first attempt to establish the order of magnitude of finite aspect ratio effects for jet-flap wings. Lift, pitching moment, and drag results are presented from pressure-plotting measurements on a jet-flap model of aspect ratio slightly less than three. These experiments were complementary to two-dimensional tests carried out at the National Gas Turbine Establishment.
An Approximate Method for the Calculation of Turbulent Boundary Layers in Diffusers
Authors: Norbury J. F.
Published: July 2016

An approximate method is described for the calculation of turbulent boundary layers in which the turbulence is developed before the commencement of the adverse pressure gradient, as in most diffuser layers. It is based on a method due to Spence which has been modified and also extended to the calculation of three-dimensional diverging layers such as occur in ducts whose breadth is increasing. The velocity profiles occurring in a diverging layer are examined and it is shown that the inner part obeys the universal logarithmic law, as in two-dimensional layers. This result is used to obtain an equation for the form parameter in diverging layers, by substitution in the equation of motion and incorporation of the equations of momentum and continuity for diverging flow. The form parameter equation contains a term involving the gradient of shear stress at y = θ and values of this term are obtained by the analysis of experimental data and the substitution of known values for all the other terms in the form parameter equation. Values of the term involving shear stress gradient are then correlated in terms of known boundary layer quantities, and the resulting correlation allows the formulation of a step-by-step method for the solution of the form parameter equation. This may be used in conjunction with the momentum equation to predict the boundary layer growth. It was not found possible to effect a satisfactory correlation for boundary layers on lifting aerofoils, in which the turbulence develops within the adverse pressure gradient, and the method cannot be used for the prediction of such layers. The results of a number of calculations are given.
Matrix Inversion by Partitioning
Authors: Kosko Eryk
Published: July 2016

A systematic discussion of partitioning as a tool for matrix inversion is presented, together with various methods and applications which have been of help in actual computations. New concepts are introduced, among them those of super-matrix and of square partitioning. The most usual type of partitioning, that into 2x2 sub-matrices, is discussed in detail, showing the orderly arrangement of the calculations in an auxiliary matrix. Further sections deal with matrices of the continuant type, and with special types of symmetry in the arrangement of the sub-matrices. The greatest advantage of the method of partitioning for the inversion of these types (as compared with the elimination method) lies in a considerable reduction in the number of arithmetical operations.
Notes on the Mathematical Design of Nozzles and Wind Tunnel Contractions
Authors: Bloomer N. T.
Published: July 2016

In this work the co-ordinates of three-dimensional nozzles of several types have been obtained as explicit functions, and some shapes have been plotted. It is hoped that some of these might be of use in cases where smooth uniform fluid flow is desired. The design of a particular nozzle shape in the presence of a plane boundary is given: previously any equations obtained have been too intractable to use.
Some Early Jet Flap Experiments
Authors: Dimmock N. A
Published: July 2016

The “second stage” two-dimensional jet flap experiments are briefly described and some of the results presented with comments. The relative simplicity of these experiments and the measure of their agreement with the theory provides, it is hoped, yet another illustration of the value of comparatively simple experiments in the early stages of work on a novel idea.
On the Generation of the Streamwise Component of Vorticity for Flows in Rotating Passages
Authors: Smith Austin G.
Published: July 2016

A method is presented for the calculation of the streamwise component of vorticity, for flows in rotating passages. The method may be regarded as an extension of the methods applied in recent years to the calculation of secondary flows in stationary passages.

Attention is concentrated on the quantityI=p+½ρV2−½ρU2,whereVis the fluid velocity relative to the rotor andUis the rotor tangential velocity.Iremains constant along a streamline in the rotor, and is found to enter into the equation for the generation of vorticity in much the same way as the total head enters for flow in stationary passages.

An approximate calculation of the streamwise vorticity generated in a simple axial-flow rotor is made, and qualitative consideration is given to the flow in a centrifugal impeller. Just as for the calculation of secondary flows in stationary passages, an approximate shape of the streamline must be assumed before the secondary flows can be calculated.
A Simplified Method for Estimating the Performance of Supersonic
Ram-Jets
Authors: Beeton A. B. P.
Published: July 2016

Curves are presented which, together with a knowledge of the intake
performance, enable ram-jet thrust coefficients and specific consumption
figures to be obtained quickly and accurately in the range M = 1·0 to
3·0.
On the Accuracy of the Representation of a Lifting Line by a Finite Set
of Horseshoe Vortices
Authors: Collar A. R.
Published: July 2016

The paper examines the error involved when the continuous distribution
of lift on an unswept lifting surface is represented by a finite number of
horseshoe vortices, the strengths of which are determined by a prescribed
downwash. Attention is directed mainly to the case of elliptic loading, but
an anti-symmetrical case is also studied to ensure that the conclusions are
not peculiar to the elliptic case.
Some Identities on Structural Flexibility after Buckling
Authors: Mansfield E. H.
Published: July 2016

This paper gives some identities concerning the flexibility of certain
elastic structures, including flat plates, at the onset of buckling and
subsequently. The identities have a useful application in determining the
flexibility and the rate of change of flexibility with load for structures
in which the mode in the buckled state changes continuously with
load.
A Note on the Drag of Wing-Body Combinations in Linearised Supersonic
Flow
Authors: Fraenkel L. E.
Published: July 2016

In this note Ward's “area-transfer rule” is modified in order to make it
more suitable for configurations with fuselages or nacelles which are
neither slender nor smooth (although they are assumed to have small profile
slope). The body source strength of Ward's analysis, which is appropriate
only for smooth, slender bodies, is replaced by a source strength which is
valid more generally. However, the drag contributions of the body
multi-sources and of the interference field are still neglected, so that the
theory is tentative rather than rigorous.
Turbulent Shear Layer Re-Attachment with Special Emphasis on the Base Pressure Problem
Authors: McDonald H.
Published: July 2016

An analysis is presented which enables the boundary-layer thickness parameters of a re-attaching shear layer to be determined when the free-stream flow upstream of the base is supersonic, the base pressure is known, and die initial boundary layer is turbulent. The application of this analysis to some experimental results, on the flow behind blunt-trailing-edge wings and over a back-step where both the base pressure and the initial boundary layer are known, would appear to indicate that the re-attached profile could be specified by one parameter, namely the transformed shape parameter, the transformation used being a turbulent analogue of the well-known Stewartson-Illingworth transformation of the laminar boundary layer and where the shape parameter is defined as the ratio of boundary-layer displacement to momentum thickness. By adopting a value of the shape parameter in advance, it is possible to use the analysis to determine the base pressure by an iterative process and so, on this basis, it is suggested that this analysis is used to replace the existing recompression criterion of the Chapman-Korst model of separated flow which aims to predict base pressures and is known to be capable of improvement.

As part of this investigation, an improvement had to be made to the existing compressible turbulent shear layer velocity profiles of Korst and others and this was achieved by means of the compressibility transformation.
Interaction of a Shock Wave with a Turbulent Boundary Layer Disturbed by Injection
Authors: Squire L.C. , Smith M.J.
Published: July 2016

An experimental investigation has been made to study the interaction between an incident oblique shock wave and a turbulent boundary layer on a solid surface downstream of a porous surface with air injection through the porous surface. The results are clearly of direct interest to the design of cooled turbine blades. However, the boundary-layer profiles in the absence of the shock are similar to those in a boundary layer subjected to an adverse pressure gradient so that the results at the interaction also give some indication of the effects of an isentropic compression upstream of a shock/boundary-layer interaction. The experiments show the surprising result that the shock strength to produce incipient Separation is virtually independent of the shape of the boundary-layer profile upstream of the interaction, although the scale of the interaction increases with increase in the injection rate.
Effect of Base Slant on Flow in the Near Wake of an Axisymmetric Cylinder
Authors: Morel Thomas
Published: July 2016

The effects of slanting the base of a slender axisymmetric cylinder (length/diameter ratio of 9), aligned with the flow, was studied experimentally. The body was equipped with interchangeable rear ends covering a range of slant angles between 0° (vertical) and 70°. It was found that the base slant has a very dramatic effect on body drag, particularly in a relatively narrow range of slant angles where the drag coefficient exhibits a large local maximum (over-shoot). Detailed study of the flow showed that the drag overshoot is related to the existence of two very different Separation patterns on the slanted base. One pattern is similar to that found behind axisymmetric bodies with no base slant, and its main feature is the presence of a closed Separation region adjacent to the base. The other pattern is highly three-dimensional with two streamwise vortices forming along the sides of the slanted base. This pattern sets in very abruptly at a “critical” slant angle α ∼ 47°. Drag force measurements showed that, at first, the drag coefficient slowly increases with the slant angle, but then jumps suddenly upwards to more than double its baseline value (from CD = 0.24 to CD = 0.625) at the critical angle. At angles higher than that CD decreases again, and at 70° it is about equal to the baseline value. Further effects of the slant angle are the generation of a large side force and a significant increase in near-wake flow periodicity.
Changes in fruit, vegetable and juice consumption after the diagnosis of type 2 diabetes: a prospective study in men
Authors: Olofsson Camilla , Discacciati Andrea , Åkesson Agneta , Orsini Nicola , Brismar Kerstin , Wolk Alicja
Published: July 2016

Given the importance of prevention of complications in type 2 diabetes (T2D), we aimed to examine changes over time in consumption of fruits, vegetables and juice among men who were diagnosed with T2D in comparison with men without diabetes. The prospective Cohort of Swedish Men, aged 45–79 years in 1997, was used to examine changes in diet after diagnosis of T2D. Dietary intake was assessed using FFQ in 1997 and 2009. In all, 23 953 men who were diabetes free at baseline (1997) and completed both FFQ were eligible to participate in the study. Diagnosis of T2D was reported by subjects and ascertained through registers. Multivariable linear mixed models were used to examine changes in mean servings/week over time. In total, 1741 men developed T2D during the study period. Increased consumption of vegetables and fruits was observed among those who developed T2D (equivalent to 1·6 servings/week, 95 % CI 1·08, 2·03) and men who remained diabetes free (0·7 servings/week, 95 % CI 0·54, 0·84). Consumption of juice decreased by 0·6 servings/week (95 % CI −0·71, −0·39) among those who developed T2D and increased by 0·1 servings/week (95 % CI 0·05, 0·15) in those who were diabetes free. Changes over time and between groups were statistically significant. Although improvements in diet were observed, only 36 % of those with T2D and 35 % of those without diabetes consumed ≥5 servings of fruits and vegetables/d in 2009.
Reproducibility and validity of dietary patterns identified using factor analysis among Chinese populations
Authors: Hong Xin , Ye Qing , Wang Zhiyong , Yang Huafeng , Chen Xupeng , Zhou Hairong , Wang Chenchen , Chu Wenjie , Lai Yichao , Sun Liuyuan , Wang Youfa , Xu Fei
Published: July 2016

In the present study, we evaluated the reproducibility and validity of dietary patterns among Chinese adult populations. A random subsample of 203 participants (aged 31–80 years) from a community-based nutrition and health survey was enrolled. An eighty-seven-item FFQ was administered twice (FFQ1 and FFQ2) 1 year apart; four 3 consecutive day, 24-h dietary recalls (24-HDR, as a reference method) were performed between the administrations of the two FFQ every 3 months. Dietary patterns from three separate dietary sources were derived using factor analysis based on twenty-eight predefined food groups. Comparisons between dietary pattern scores were made by using Pearson’s or intraclass correlation coefficients (ICC), cross-classification analysis, weightedκstatistic and Bland–Altman plots; the four major dietary patterns identified from FFQ1, FFQ2 and 24-HDR were similar. Regarding reproducibility, ICC forz-scores between FFQ1 and FFQ2 were all >0·6 for dietary patterns. The ‘animal and plant protein’ pattern had the highest ICC of 0·870. For validity, the adjusted Pearson’s correlation coefficients for dietary patternz-scores between two FFQ and the mean of four 3 consecutive day 24-HDR ranged from 0·387 for the ‘Chinese traditional’ pattern to 0·838 for the ‘animal and plant protein’ pattern. More than 75 % of the participants were classified into the same or adjacent quartile, and <5 % were misclassified into opposite quartiles. The weightedκranged from 0·259 to 0·680. Bland–Altman plots indicated that no significant deviation was found between two dietary assessment methods. Our findings indicate a good reasonable reproducibility and a reasonable validity of dietary patterns derived by factor analysis in China.
L'analyse automatisée du ton médiatique : construction et utilisation de la version française du Lexicoder Sentiment Dictionary
Authors: Duval Dominic , Pétry François
Published: July 2016

Cet article introduit un nouveau dictionnaire permettant l'analyse automatisée du ton des médias francophones, que nous avons appelé Lexicoder Sentiment Dictionnaire Français (LSDFr) en référence au lexique anglophone de Young et Soroka (2012), Lexicoder Sentiment Dictionary (LSD) à partir duquel le LSDFr a été construit. Une fois construit, nous comparons le LSDFr au seul autre dictionnaire francophone existant de ce genre, Linguistic Inquiry and Word Count (LIWC). Nous testons ensuite la validité interne du LSDFr en le comparant avec un corpus de textes codés manuellement. Nous testons enfin la validité externe du LSDFr en mesurant jusqu'où le ton médiatique, calculé à l'aide de notre dictionnaire, prédit les intentions de vote des Québécois lors des quatre dernières campagnes électorales. En développant cet outil, notre objectif est de permettre à d'autres chercheurs d'effectuer des analyses médiatiques dans un corpus de textes comparables en français.
Feeding habits of wahoo (Acanthocybium solandri) in the eastern Pacific Ocean
Authors: Mendoza-ávila Molker , Zavala-Zambrano Gabriela , Galván-Magaña Felipe , Loor-Andrade Peggy
Published: July 2016

Stomach content analysis was used to assess the feeding habits ofAcanthocybium solandribased on samples obtained on purse seine fishing trips off the Pacific coasts of Central and South America. A total of 226 samples were obtained; 160 stomachs contained food and 33 prey taxa were identified. Based on the Prey Specific Index of Relative Importance (%PSIRI), cephalopods and fishes were the main prey groups (50.4 and 49.5% PSIRI).Dosidicus gigas(23.4% PSIRI),Stenoteuthis oualaniensis(9.9% PSIRI) andArgonautaspp. (9.4% PSIRI) were the most representative prey.Acanthocybium solandriis a generalist predator based on the results of the Amundsen analysis and niche breadth (Ba= 1).
And then there was one:Polydora uncinataandPolydora hoplura(Annelida: Spionidae), the problematic polydorid pest species represent a single species
Authors: Sato-Okoshi Waka , Abe Hirokazu , Nishitani Goh , Simon Carol A.
Published: July 2016

It is necessary to monitor shell-associated polydorid worms owing to the risk that they pose to commercially important molluscs. This requires accurate identification, but is often hampered by morphological similarities among species, insufficient type specimens, and abridged species descriptions. Thus morphological characteristics and molecular sequences of the most harmful polydorid species,Polydora uncinatafrom Japan and Australia andPolydora hoplurafrom South Africa were compared to determine whether they represent two morphologically similar, but genetically distinct species, or a single species. A wide range of morphological variation (with respect to size, length of caruncle and pigmentation patterns) was observed in each species and population, and their variations largely overlapped and revealed them to be at the intraspecific level of a single species. This was confirmed by gene sequences of nuclear 18S and 28S rRNA that were completely identical forP. uncinataandP. hoplura. The mitochondrial 16S rRNA andcyt bgene analyses also showed no genetic differences between these two species. The tree topology of the mitochondrialcyt bgene did not reflect geographic differences but instead suggests artificial transportation of the species. We recommend the synonymization ofP. uncinatawithP. hoplura.
Uniqueness of patterns generated by repetition
Authors: Mason John
Published: July 2016

Consider two related tasks:

A) The diagram below displays a fragment of a pattern known to extend indefinitely and to be generated by an endlessly repeating pattern. What kind of shading will the 137th cell have? What number cell will the 137th white cell be in?

B) What is the next term in the sequence 3, 6, 11, 18, 27, …?

Tasks like the first can provide excellent experience of detecting and expressing generality as one route to algebra, but only if learners are first asked to describe a structural relationship which generates the succeeding items. Tasks like the second feature in intelligence tests, but it is well known that such tasks are mathematically incomplete.
An approximation to the arithmetic-geometric mean
Authors: Jameson G. J. O.
Published: July 2016

Given positive numbers a > b, consider the ‘agm iteration’ given by a0 = a, b0 = b and

At each stage, the two new numbers are the arithmetic and geometric means of the previous two. It is easily seen that bn < an, (an) is decreasing, (bn) is increasing and an + 1 − bn + 1 < ½(an − bn), and hence that (an) and (bn) converge to a common limit, which is called the arithmetic-geometric mean of a and b. We will denote it by M (a, b).
Graph-theoretic models for the Fibonacci family
Authors: Koshy Thomas
Published: July 2016

The well-known Fibonacci and Lucas numbers continue to faxcinate the mathematical community with their beauty, elegance, ubiquity, and applicability. After several centuries of exploration, they are still a fertile ground for additional activities, for Fibonacci enthusiasts and amateurs alike.

Fibonacci numbers Fn and Lucas numbers Ln belong to a large integer family {xn}, often defined by the recurrence xn = xn−1 + xn−2, where x1 = a, x2 = b, and n ≥ 3. When a = b = 1, xn = Fn; and when a = 1 and b = 3, xn = Ln. Clearly, F0 = 0 and L0 = 2. They satisfy a myriad of elegant properties [1,2,3]. Some of them are:

In this article, we will give a brief introduction to the Q-matrix, employ it in the construction of graph-theoretic models [4, 5], and then explore some of these identities using them.

In 1960 C.H. King studied the Q-matrix
Paradoxical Euler: Integrating by Differentiating
Authors: Fabian Andrew , Nguyen Hieu D.
Published: July 2016

Every student of calculus learns that one typically solves a differential equation by integrating it. However, as Euler showed in his 1758 paper (E236), Exposition de quelques paradoxes dans le calcul intégral (Explanation of certain paradoxes in integral calculus) [1], there are differential equations that can be solved by actually differentiating them again. This initially seems paradoxical or, as Euler describes it in the introduction of his paper:

Here I intend to explain a paradox in integral calculus that will seem rather strange: this is that we sometimes encounter differential equations in which it would seem very difficult to find the integrals by the rules of integral calculus yet are still easily found. not by the method of integration. but rather in differentiating the proposed equation again; so in these cases, a repeated differentiation leads us to the sought integral.
How many dead ends in a derangement?
Authors: Lewis Barry
Published: July 2016

This article is concerned with two sequences and the matrices they induce. The first, the Derangement sequence is well known to readers of the Gazette. It has been written about and its properties derived in many ways and on many previous occasions [1 – 11]. In contrast the second sequence, the Deadend sequence, is not well known – and certainly not the name since I made that up while writing this article. However, I want to explore these sequences in a single, systematic way. For the former it gives a fresh account of its properties, and for the latter it sets out corresponding results. The surprise is that they tum out to be closely related; surprising since their very different definitions mask such a connection. More than this, most of these properties may be established in the most fundamental way, based on elegant enumerative arguments. So they are free of specialised expertise or technique and may be enjoyed just as they are.
How to choose your relations
Authors: Crilly Tony , Fletcher Colin R.
Published: July 2016

Mathematicians are fascinated by relatios and have worked our extensive theories about them. The treatments tend to be abstract and sometimes the basic ideas are lost in the abstraction. Here we investigate some common ground between mathematical relations and down-to-earth genealogy, the study of family relations.

Family relations have been studied by mathematicians, perhaps none more playfully than Thomas P. Kirkman (the nineteenth century expert in combinatorial mathematics) in his little puzzle rhyme he sent to the Educational Times [1, p.117]:

Baby Tom of Bay Hugh

The nephew is and uncle too;

In how many ways can this be true
Miscellaneous triangle properties
Authors: Scott J. A.
Published: July 2016

In this note we will discuss five topics from triangle geometry and occasionally encounter something new. Areal coordinates (presented as Appendix A in [1]) will be used throughout, with the exception of the final section where it is advantageous to employ Cartesians.

The topics are:

(1) examples of collinearities where the distance ratios for important points vary with triangle shape;

(2) a pencil of lines which includes the Fermat, Napoleon and Vecten axes;

(3) two more circles related to the Lester circle;

(4) the family of rectangular hyperbolae which circumscribe the triangle of referenceABCand whose principal member is the Kiepert hyperbola [2];

(5) Cartesian coordinates leading to a solution of the ‘Euler disc problem’ [3].
Village senior centres and the living arrangements of older people in rural China: considerations of health, land, migration and intergenerational support
Authors: LIU HUIJUN , EGGLESTON KAREN N. , MIN YAN
Published: July 2016

China is experiencing rapid urbanisation and population ageing, alongside sometimes contentious rural land consolidation. These on-going social, economic, political and demographic changes are especially problematic for older people in rural areas. In these regions, social and institutional support arrangements are less developed than in urban areas; older people have few options for re-settlement but are resistant to or incapable of adjusting to high-rise apartment living. In 2012–13, we gathered rich qualitative and quantitative data on over 600 older residents in 12 villages under the jurisdiction of City L in north-east coastal China to analyse residents’ living arrangement choices during the village renovation process. We compared villages with and without senior centres to shed light on the correlates of co-residence and independent living. Senior centres play a role in balancing the burden on rural Chinese families resulting from population ageing, smaller families, widespread migration for work, and the rapid urbanisation that is restructuring land rights and social support arrangements.
Whitney regularity of the image of the Chevalley mapping
Authors: Barbançon Gérard P.
Published: July 2016

A compact set K ⊂ ℝn is Whitney 1-regular if the geodesic distance in K is equivalent to the Euclidean distance. Let P be the Chevalley map defined by an integrity basis of the algebra of polynomials invariant by a reflection group. This paper gives the Whitney 1-regularity of the image by P of any closed ball centred at the origin. The proof uses the works of Givental', Kostov and Arnol'd on the symmetric group. It needs a generalization of a property of the Vandermonde determinants to the Jacobian of the Chevalley mappings.
Liouvillian first integrals for a class of generalized Liénard polynomial differential systems
Authors: Llibre Jaume , Valls Clàudia
Published: July 2016

We study the existence of Liouvillian first integrals for the generalized Liénard polynomial differential systems of the form xʹ = y, yʹ = –g(x) – f(x)y, where f(x) = 3Q(x)Qʹ(x)P(x) + Q(x)2Pʹ(x) and g(x) = Q(x)Qʹ(x)(Q(x)2P(x)2 – 1) with P,Q ∈ ℂ[x]. This class of generalized Liénard polynomial differential systems has the invariant algebraic curve (y + Q(x)P(x))2 – Q(x)2 = 0 of hyperelliptic type.
Nasopharyngeal bacterial carriage in young children in Greenland: a population at high risk of respiratory infections
Authors: NAVNE J. E. , BØRRESEN M. L. , SLOTVED H. C. , ANDERSSON M. , MELBYE M. , LADEFOGED K. , KOCH A.
Published: July 2016

The incidence of childhood respiratory infections in Greenland is among the highest globally. We performed a population-based study of 352 Greenlandic children aged 0–6 years aiming to describe rates and risk factors for carriage of four key bacteria associated with respiratory infections, their antimicrobial susceptibility and inter-bacterial associations. Nasopharyngeal swabs were tested for Streptococcus pneumoniae grouped by serotypes included (VT) or not included (NVT) in the 13-valent pneumococcal conjugate vaccine, non-typable Haemophilus influenzae (NTHi), Staphylococcus aureus and Moraxella catarrhalis. S. pneumoniae was detected from age 2 weeks with a peak carriage rate of 60% in 2-year-olds. Young age and having siblings attending a daycare institution were associated with pneumococcal carriage. Overall co-colonization with ⩾2 of the studied bacteria was 52%. NTHi showed a positive association with NVT pneumococci and M. catarrhalis, respectively, M. catarrhalis was positively associated with S. pneumoniae, particular VT pneumococci, whereas S. aureus were negatively associated with NTHi and M. catarrhalis. Nasopharyngeal bacterial carriage was present unusually early in life and with frequent co-colonization. Domestic crowding increased odds of carriage. Due to important bacterial associations we suggest future surveillance of pneumococcal conjugate vaccine's impact on carriage in Greenland to also include other pathogens.
PAEAN: Portable and scalable runtime support for parallel Haskell dialects
Authors: BERTHOLD JOST , LOIDL HANS-WOLFGANG , HAMMOND KEVIN
Published: July 2016

Over time, several competing approaches to parallel Haskell programming have emerged. Different approaches support parallelism at various different scales, ranging from small multicores to massively parallel high-performance computing systems. They also provide varying degrees of control, ranging from completely implicit approaches to ones providing full programmer control. Most current designs assume a shared memory model at the programmer, implementation and hardware levels. This is, however, becoming increasingly divorced from the reality at the hardware level. It also imposes significant unwanted runtime overheads in the form of garbage collection synchronisation etc. What is needed is an easy way to abstract over the implementation and hardware levels, while presenting a simple parallelism model to the programmer. The PArallEl shAred Nothing runtime system design aims to provide a portable and high-levelshared-nothingimplementation platform for parallel Haskell dialects. It abstracts over major issues such as work distribution and data serialisation, consolidating existing, successful designs into a single framework. It also provides an optionalvirtualshared-memory programming abstraction for (possibly) shared-nothing parallel machines, such as modern multicore/manycore architectures or cluster/cloud computing systems. It builds on, unifies and extends, existing well-developed support for shared-memory parallelism that is provided by the widely used GHC Haskell compiler. This paper summarises the state-of-the-art in shared-nothing parallel Haskell implementations, introduces the PArallEl shAred Nothing abstractions, shows how they can be used to implement three distinct parallel Haskell dialects, and demonstrates that good scalability can be obtained on recent parallel machines.
Visualizing Iraq: oil, cinema, and the modern city
Authors: DAMLUJI MONA
Published: July 2016

Summoning the popularity and prestige of cinema, the Iraq Petroleum Company (IPC) invented the image of Baghdad for Iraqi audiences as the sight/site of oil modernity in the 1950s. In other words, oil urbanization, or the modernization of the city as shaped by the petroleum industry and its revenues, in Iraq cannot be understood apart from the representation of Baghdad as visible evidence of petroleum's promise to benefit the national population. The British-controlled oil company in Iraq produced a programme of at least two-dozen sponsored films and cine-magazine episodes between 1951 and 1958, which this essay examines as an emblematic case of neo-colonial film, constituting an archive of media practices that bridge the categories of colonial film on one hand, and industrial film on the other. After World War II, the Atlantic Charter reinforced the right to democratic self-rule as a global norm and the British state developed creative tactics to abet its continued control over strategic resources in its colonized territories. Oil above all became central to this story and, as this essay will show, British oil companies played a fundamental role towards reinventing the imperial project in the post-colonial context of Iraq. Through a contextualized analysis of the IPC films, I argue that the company public relations office utilized the conventional approaches and standard formats of colonial and industrial film – including montage, scripted voiceover and staged b-roll – to narrativize the association between neo-colonialist practices of oil extraction and national development as causal, inherent and positive.
San Francisco views: Robert Bechtle and the reformulation of urban vision
Authors: GILMAN BRIDGET
Published: July 2016

When Photorealism arrived on the art scene in the 1960s, it received considerable media attention for its striking illusionism and unparalleled commitment to fusing painting and photography. But many judged the style to be merely retrograde realism disguised by the use of contemporary source photographs or, more harshly, as an unthinking reproduction of capitalist culture – i.e. a kind of toothless Pop art slickly rendered for the masses. Though the style now constitutes a familiar part of the contemporary art world, few have sought to understand or mitigate several decades of critical antipathy and neglect. This essay examines painter Robert Bechtle's work, contra the historic assumption of Photorealism's social irrelevance. Bechtle's images of San Francisco, defined by architecture and automobiles ubiquitous in post-1945 Californian neighbourhoods, present the city without overt commentary. Yet, through this seemingly ordinary iconography, the artist upends deep-rooted urban visual paradigms, linking the traditionally vaunted city centre to its apparently subsidiary suburbs. Bechtle offers the viewer not iconic landmarks or arresting vistas, but rather a way to comprehend how everyday life in the city is informed by significant configurations of residential architecture, under-remarked geographic particularities and historical development that blurs the distinction between centre and periphery. These representational strategies are central to understanding the ways in which the Bay Area – and indeed much of post-war America – is experienced as built environment and social space.
Buses from nowhere: television and anti-busing activism in 1970s urban America
Authors: DELMONT MATT
Published: July 2016

‘Busing’, in which students were transported by school buses to achieve court-ordered or voluntary school desegregation, became one of the nation's most controversial civil rights issues in the decades after Brown vs. Board of Education (1954). Focusing on Florida Governor Claude Kirk and Pontiac housewife activist Irene McCabe, this essay examines how busing opponents turned the conventions of television news – its emphasis on newsworthy events and crisis; its selective use of historical context; and its nominal political neutrality – to their advantage, staging television friendly protests that positioned mothers and children as victims of activist judges and federal bureaucrats, and framed their support for segregated neighbourhoods and schools in the colour-blind rhetoric of homeowners’ rights. For politicians who aspired to the national stage, like Florida Governor Claude Kirk, busing offered a recognizable issue on which to take a stand. When Kirk protested court-ordered busing by suspending a local school board in Manatee County (Bradenton, Florida) and appointing himself school superintendent, he was not only appealing to Florida voters but also to television viewers in cities like Nashville, St Louis and Seattle, many of whom wrote to convey their support. When Vice-President Spiro Agnew complained that television network news ‘can elevate men from obscurity to national prominence within a week’, he was referring to Black Power author and activist Stokely Carmichael, but television news also propelled grassroots anti-busing activists like Irene McCabe to national prominence. McCabe, who staged a widely covered six-week march from Pontiac to Washington DC to protest busing, made frequent television appearances because networks deemed her newsworthy, not necessarily because newscasters agreed with her politics. Repeated television coverage turned relatively minor busing battles in Bradenton and Pontiac into national news and established Kirk and McCabe as icons of busing opposition in the early 1970s.
Introduction
Authors: DELMONT MATT
Published: July 2016

The fields of urban history and visual culture both thrive on expansive horizons. Streets and rivers, neighbourhoods and stadia, festivals and parks populate the work of urban historians, who examine these and other subjects from local, metropolitan, regional, national and transnational perspectives. Viewing these urban themes with and through visual culture increases the potential areas of analysis exponentially. Not only do photography, film, television and advertising produce countless images of urban spaces, visual culture encourages scholars to take seriously the ways of seeing and practices of looking that shape how people understand and engage with the metropolis. Visual technologies, both old and new, make places meaningful in ways that have broad cultural, political and economic consequences. As digital tools continue to make more urban spaces visible to more people, scholars have a crucial role to play in researching, organizing, contextualizing and analysing these myriad urban sights.
CENTRAL LIMIT THEOREM FOR THE MODULUS OF CONTINUITY OF AVERAGES OF OBSERVABLES ON TRANSVERSAL FAMILIES OF PIECEWISE EXPANDING UNIMODAL MAPS
Authors: de Lima Amanda , Smania Daniel
Published: July 2016

Consider a$C^{2}$family of mixing$C^{4}$piecewise expanding unimodal maps$t\in [a,b]\mapsto f_{t}$, with a critical point$c$, that is transversal to the topological classes of such maps. Given a Lipchitz observable$\unicode[STIX]{x1D719}$consider the function$$\begin{eqnarray}{\mathcal{R}}_{\unicode[STIX]{x1D719}}(t)=\int \unicode[STIX]{x1D719}\,d\unicode[STIX]{x1D707}_{t},\end{eqnarray}$$where$\unicode[STIX]{x1D707}_{t}$is the unique absolutely continuous invariant probability of$f_{t}$. Suppose that$\unicode[STIX]{x1D70E}_{t}>0$for every$t\in [a,b]$, where$$\begin{eqnarray}\unicode[STIX]{x1D70E}_{t}^{2}=\unicode[STIX]{x1D70E}_{t}^{2}(\unicode[STIX]{x1D719})=\lim _{n\rightarrow \infty }\int \left(\frac{\mathop{\sum }_{j=0}^{n-1}\left(\unicode[STIX]{x1D719}\circ f_{t}^{j}-\int \unicode[STIX]{x1D719}\,d\unicode[STIX]{x1D707}_{t}\right)}{\sqrt{n}}\right)^{2}\,d\unicode[STIX]{x1D707}_{t}.\end{eqnarray}$$

We show that$$\begin{eqnarray}m\left\{t\in [a,b]:t+h\in [a,b]\text{ and }\frac{1}{\unicode[STIX]{x1D6F9}(t)\sqrt{-\log |h|}}\left(\frac{{\mathcal{R}}_{\unicode[STIX]{x1D719}}(t+h)-{\mathcal{R}}_{\unicode[STIX]{x1D719}}(t)}{h}\right)\leqslant y\right\}\end{eqnarray}$$converges to$$\begin{eqnarray}\frac{1}{\sqrt{2\unicode[STIX]{x1D70B}}}\int _{-\infty }^{y}e^{-\frac{s^{2}}{2}}\,ds,\end{eqnarray}$$where$\unicode[STIX]{x1D6F9}(t)$is a dynamically defined function and$m$is the Lebesgue measure on$[a,b]$, normalized in such way that$m([a,b])=1$. As a consequence, we show that${\mathcal{R}}_{\unicode[STIX]{x1D719}}$is not a Lipchitz function on any subset of$[a,b]$with positive Lebesgue measure.
Building value chains for indigenous fruits: lessons from camu-camu in Peru
Authors: Blare Trent , Donovan Jason
Published: July 2016

Governments and NGOs have enthusiastically promoted value chains for lesser-known indigenous fruits in the pursuit of poverty reduction and other development goals. This paper examines experiences in Peru in building the value chain for camu-camu—a fruit native to the Amazon that is in the process of being domesticated. We look at interventions to build the chain, the environment in which the chain operates, the implications of chain development on livelihoods, and prospects for future chain development. Information was collected from gray literature as well as from primary data from household and key informant interviews. The results of this study suggest that the emergence of the camu-camu chain has led to higher farm income without generating large trade-offs in livelihood activities or the environment. However, the results also demonstrate an unrealized potential to achieve greater impact at scale due to gaps in services and inputs, limited coordination among farmers and chain actors, and a risky business environment. Building value chains for lesser-known fruits will require more than a techo-managerial focus on smallholder production. Greater attention is required to build stronger public–private collaboration to expand and diversify markets, with particular attention on strengthening institutions and growing local markets for high-value products.
Lentil enhances agroecosystem productivity with increased residual soil water and nitrogen
Authors: Gan Yantai , Hamel Chantal , Kutcher H. Randy , Poppy Lee
Published: July 2016

Lentil (Lens culinaris Medikus) may have a potential to enhance the productivity of agroecosystems in dry areas where water and nutrients are limited. This study quantified soil water, residual soil nitrogen (N), and crop yields in lentil-based systems in comparison with continuous cereal and conventional summerfallow systems. A 3-yr cropping sequence study was conducted for three cycles in Saskatchewan (50.28°N, 107.79°W) from 2007 to 2011. On average, soil retained 187, 196 and 337 mm of water in the 0–1.2 m depth at crop harvest in 2008, 2009 and 2010, respectively. Summerfallow contained the same amounts of water as the cropped treatments at the harvest in 2009 and 2010. However, in 2008, summerfallow contained more soil water than the cropped treatments. The effect of lentil cultivar on soil water conservation varied with years; the cultivars Glamis, Laird and Sedley conserved highest amounts of soil water by the planting time of 2009 and 2010, but no differences were found among cultivars in 2011. Soil available N (NO3− + NH4+) at spring planting time was 50.4 kg ha−1 in the preceding lentil treatments, which was 44% higher compared with preceding barley or flax, but was 25% lower compared with preceding summerfallow. Lentil cultivars had a similar amount of soil residual N. Grain production in the 3-yr rotation averaged 6.3 t ha−1 per rotation for the wheat–lentil–durum system and 6.8 t ha−1 for the wheat–cereal–durum monoculture, averaging 36% greater compared with wheat–summerfallow–durum system. The lentil system increased total grain production through the access of residual soil water and biologically fixed N, whereas continuous cereal system relies on inorganic fertilizer input for yield. Summerfallow system relies on ‘mining’ the soil for nutrients. We conclude that the adoption of lentil systems will enhance grain production through the use of residual soil water and available N.