bluuebunny/crossref_metadata_2025_split huggingface dataset:
Health Care of Latino Children with Autism and Other Developmental Disabilities: Quality of Provider Interaction Mediates Utilization
Authors: Parish Susan , Magaña Sandra , Rose Roderick , Timberlake Maria , Swaine Jamie G 
Published: July 2012

Abstract
This study examines access to, utilization of, and quality of health care for Latino children with autism and other developmental disabilities. We analyze data from the National Survey of Children with Special Health Care Needs (N  =  4,414 children with autism and other developmental disabilities). Compared with White children, Latino children with autism and other developmental disabilities had a consistent pattern of worse health care access, utilization, and quality. We then test mediation models to determine if health care quality mediates the relationship between ethnicity and health care utilization disparities. Three of four quality indicators (provider does not spend enough time with child, provider is not culturally sensitive, and provider does not make parent feel like a partner) were significant mediators. These analyses suggest that interventions targeted at improving providers' cultural sensitivity and behavior during the clinical encounter may reduce disparities in the health care utilization of Latino children with autism and other developmental disabilities.
Tweeting About Testing: Do Low‐Income, Parenting Adolescents And Young Adults Use New Media Technologies To Communicate About Sexual Health?
Authors: Divecha Zai , Divney Anna , Ickovics Jeannette , Kershaw Trace 
Published: July 2012

CONTEXTLittle research exists about adolescents’ and young adults’ use of new media technologies to communicate about sexual health. Understanding how young people at high risk for STDs use these technologies can inform media‐based interventions.METHODSBetween October 2010 and March 2011, a sample of 94 low‐income, parenting adolescents and young adults recruited at clinics in Connecticut completed an audio computer‐assisted self‐interview about their use of media technologies, communication with friends about sexual health and willingness to use media technologies for such communication. Descriptive statistics were calculated; characteristics of those willing and those unwilling to communicate were compared in chi‐square, t and Mann–Whitney tests.RESULTSNinety‐three percent of participants had mobile phones; 71% used Facebook regularly. Participants discussed sexual health more often with close friends than with casual friends, and preferred to have such conversations in person (71% with close friends and 68% with casual friends), over the phone (52% and 45%) or via text message (30% and 28%), rather than through social networking sites (0–9% and 2–7%). Fewer than one‐third reported being willing to share sexual health information with friends through a specific new media technology. Those who were willing were predominantly black (59%); of those who were unwilling, 51% were Latino. Condom self‐efficacy, STD knowledge and number of Facebook friends were greater among those who were willing than among those who were unwilling.CONCLUSIONSFor conversations about sexual health, young urban parents prefer private forms of ‐communi‐cation; thus, social networking sites may not aid STD interventions.
Das Olympia-Attentat 1972
Authors: Oberloskamp Eva 
Published: July 2012

Vorspann
Der Schock des Olympia-Attentats von 1972 saß tief. Aber hatte er auch politische Konsequenzen? Eva Oberloskamp, Historikerin am Institut für Zeitgeschichte München-Berlin, geht dieser in der Forschung umstrittenen Frage äußerst umsichtig auf den Grund. Das Ergebnis ihrer aspektreichen Analyse ist klar: Das Innenministerium, das Justizministerium und das Auswärtige Amt blieben nicht untätig. Ihre Maßnahmen waren wegweisend für die internationale Kooperation auf dem Gebiet der Inneren Sicherheit.
The use of small specimens for measuring autoclave expansion of cements
Authors: Rehsi S. S. , Majumdar A. J. 
Published: July 2012

Summary The present ASTM specifications for testing autoclave expansion of cements require 500 g of cement for each specimen. In laboratory studies with experimental cements, preparation of clinkers in large quantities is inconvenient and tedious and may be quite difficult in certain circumstances. The possibility of substituting half-inch cubes for the standard specimen size recommended by the ASTM has been explored. Expansion measurements have been made with a precision micrometer. The accuracy and reproducibility of these measurements on a Portland cement have been considered with reference to similar results obtained on the same cement by the standard ASTM procedure. The agreement between the two sets of results is fair. The effect of MgO upon the autoclave expansion of cements has been assessed by using small specimens of experimental cements. In agreement with the results of previous workers, the volume expansion of cements rises very sharply beyond 5% MgO.
Short-term loading and deformation of concrete in uniaxial tension and pure torsion
Authors: Hughes B. P. , Ash J. E. 
Published: July 2012

Summary Complete stress-strain and torque-twist curves for concrete and micro-concrete under short-term loading have been obtained for single sizes and wide gap-gradings of aggregate of two different types. The importance of eliminating effects due to both aggregate absorption and the testing technique is emphasized. When the volume fractions of cement and water were kept constant, the uniaxial tensile strength, ‘modulus of elasticity/plasticity’, tensile stress at the onset of microcracking, ‘modulus of rigidity/plasticity’, and ultimate torsional strength of concrete all decreased with increasing aggregate size and with increasing proportions of coarse aggregate. The tension results confirm that there is a critical minimum ratio of fine aggregate to cement below which there is a considerable decrease in strength whereas the torsion results provide little evidence for this critical ratio.
Stress analysis of cracked reinforced and prestressed concrete thin-walled beams and shells
Authors: Zbirohowski-Koscia K. F. 
Published: July 2012

Summary This paper proposes a method for the stress analysis of thin-walled reinforced and prestressed concrete beams under the combined effect of axial force bending moments and ‘bimoments’. The assumption that plane surfaces remain plane is not applicable to beams of this type. The distribution of strains and stresses in an uncracked thin-walled beam follows closely the theory developed by Vlasov. This theory is extended here to the problem of the stress distribution in a cracked section of a reinforced concrete beam. The analysis is limited to beams of an ‘open cross-section’ working in the elastic range of internal stresses. Results of model tests at Southampton have substantiated the validity of this theory.
Testing concrete in tension and in compression
Authors: Johnston C. D. 
Published: July 2012

Summary The paper describes a new uniaxial tension test for concrete, in which the specimen is gripped by friction. The specimens are plain concrete prisms of 4 or 6 in. (10 or 15 cm) square cross-section, and the minimum length requirement permits the use of the standard flexure specimens of B.S. 1881. The test is evaluated in terms of the stress distribution, fracture distribution and eccentricity in the specimen. The standard compression tests are criticized, and an uncapped specimen of height/width ratio 2·5 is advocated. The influence of mix parameters upon the ratio of uniaxial tensile strength to compressive strength is illustrated, and it is concluded that the estimation of tensile strength from compression tests is unreliable. The indirect tensile or splitting strength and the uniaxial tensile strength are shown to differ considerably, the magnitude of the difference being very dependent upon mix parameters. Several factors are discussed which explain the variable difference between the two strengths, and it is concluded that the indirect tension test is not a simple accurate method of ascertaining the tensile strength of concrete.
Determining bond strength in fibre-reinforced composites
Authors: deVekey R. C. , Majumdar A. J. 
Published: July 2012

Summary A pull-out technique suitable for determining the interfacial bond strength for various combinations of fibres and matrix is described. In this method, a thick fibre, 0·5 to 1·0 mm in diameter, is embedded perpendicularly through a matrix material contained in a special mould and is stressed on a tensile testing machine. The value of the maximum bond load corresponds to a sharp break in the load-extension curve. Results show that the bond strength between E-glass-fibre and cement is of the same order as that between steel and cement but higher than the values reported for asbestos and cement. The work has also shown that the strength of the bond between E-glass-fibre and gypsum plaster is of similar magnitude, but that it is affected significantly by variations in water/plaster ratio.
The composition of the tricalcium aluminate and ferrite phases in Portland cement determined by the use of an electron-probe microanalyser
Authors: Fletcher K. E. 
Published: July 2012

Synopsis Each of the four main phases of Portland cement contains various elements in solid solution, the extent and nature of which may affect the hydraulic properties. A direct determination of the composition of these phases has only become possible by the use of the electron-probe microanalyser. The paper describes the analysis of the tricalcium aluminate and calcium alumino-ferrite phases. It was difficult to obtain reliable and accurate analyses of these in Portland cement clinkers and results were confirmed by the investigation of laboratory preparations where the tricalcium aluminate and calcium alumino-ferrite phases were predominant. The tricalcium aluminate phase was found to be approximately: (Ca2·78Na0·16K0·02) (Al1·75Fe0·16Mg0·07Si0·l0)O6 The calcium alumino-ferrite phase in a normal Portland cement clinker was found to be: Ca5·97Al3·23Fe2·13Si0·14Mg0·15Ti0·23Mn0·09O15 and that in a sulphate-resisting cement clinker to be: Ca6·16Al2·24Fe3·22Si0·14Mg0·07Ti0·12Mn0·03O15 The properties of a Portland cement are largely governed by the relative amounts of the four major phases present. The normal ‘Bogue’ method of compound calculation from the chemical analysis assumes that no solid solution occurs in these phases and that the cement clinker is at equilibrium. This method of compound calculation is compared, for a series of cement clinkers, with a calculation where solid solution is taken into account, with a calculation where the ferrite composition as given by X-ray diffraction is used, and also with the direct determination of the phases by X-ray diffraction and optical microscopy. It seems likely that the normal method of compound calculation underestimates the C3A content of sulphate-resisting cement clinkers.
Some tests on reinforced concrete beam-slab panels
Authors: Hayes B. , Taylor R. 
Published: July 2012

Synopsis Results of tests on ten reinforced concrete beam-slab panels are reported. The panels, which were subjected to a uniformly distributed load, were square and consisted of two-way-spanning slabs supported on, and integral with, edge beams. Variables in the investigation included the relative strengths of the beams and slabs, the layout of the slab reinforcement, and the detailing of the corner connexions. The behaviour of the slabs is discussed and, in particular, the ultimate loads are compared with those predicted by simple yield-line theory. The limitations of this theory are discussed and suggestions are made for a more accurate method of calculation to be used in design which would effect some economy in reinforcement.
High-magnesia Portland cements: studies on cements prepared with reagent-grade chemicals
Authors: Rehsi S. S. , Majumdar A. J. 
Published: July 2012

Synopsis Several Portland cement clinkers containing up to 15% MgO have been prepared with reagent-grade chemicals, and the properties of cements made from them have been investigated. In particular, the effect of variations in composition, burning temperature and cooling conditions of the clinkers upon the autoclave expansion and strength of the corresponding cements has been examined in detail. It is not possible by controlling these factors alone to produce ‘sound’ (i.e. volume-stable) Portland cements having MgO percentages much above the present limits recommended by the Standards in different countries. The addition of a suitable reactive silicate material in finely divided form, e.g. pulverized-fuel ash, effectively stabilizes high-magnesia cements and these mixtures pass the ASTM test for soundness of Portland cements. Data on the autoclave expansion and mechanical strength of these mixtures of high-magnesia cement and pfa are presented.
The creep of sealed concrete under multiaxial compressive stresses
Authors: Jordaan I. J. , Illston J. M. 
Published: July 2012

Synopsis The results of two series of creep tests on sealed concrete are presented. Uni-, bi- and triaxial states of compressive stress were applied to cubical specimens; in the first series, all loaded faces were subjected to the same level of applied stress; in the second series, different levels of stress were applied orthogonally to each specimen. Analysis of the results in terms of the volumetric and deviatoric components of creep shows that the two components can be considered as independent of each other and that both are directly proportional to stress. Their ratio is approximately constant and equal to the elastic value while the concrete is under load; this is equivalent to saying that the effective Poisson's ratio remains constant. After unloading, the ratio changes, the volumetric delayed recovery being initially faster and ceasing sooner than the concurrent deviatoric component.
Shear reinforcement of reinforced concrete beams subject to distributed loading
Authors: Smith R. B. L. 
Published: July 2012

Synopsis The shear reinforcement of beams su~iected to uniformly distributed loading, constituting a most important design case, is specified in Codes of Practice and has been treated theoretically on the basis of evidence derived from point load tests. In order to provide some direct evidence on the amount of web reinforcement required for the attainment of flexural capacity, eleven beams with varying spans and web reinforcement were tested. The results are compared with theoretical predictions and with British and American Codes of Practice.
A new tensile strength test for concrete—or a new control test?
Authors: Mayfield B. 
Published: July 2012

Synopsis This note draws attention to a new concrete tensile test proposed by the Department of Energy, Mines and Resources, Ottawa, Canada. Some preliminary trials using this method have been carried out at the University of Nottingham which concern their conclusions, and it is suggested that their apparatus may dispose of many of the objections to existing tests.
Shrinkage and creep of concrete as affected by the fineness of Portland cement
Authors: Bennett E. W. , Loat D. R. 
Published: July 2012

Synopsis Tests are reported on the shrinkage and creep of concrete made with Portland cement of three different grades of fineness, but of similar composition except for gypsum content. The programme comprised tests of unrestrained shrinkage, restrained shrinkage and cracking by a ring test, and creep over periods up to four-and-a-half years. The results indicate that there is an increase of unrestrained shrinkage and creep with finer cement but that, owing to the higher strength, there is no tendency for undesirably rapid shrinkage cracking to occur.
The diagonal cracking strength of continuous prestressed concrete beams
Authors: Jena B. , Pannell F. N. 
Published: July 2012

Synopsis Results of tests on 20 two-span un bonded prestressed concrete I beams failing infiexure and shear under symmetrical point loads are presented. Under shear failure, the mechanism offailure being that of diagonal tension cracking only, a fracture criterion suitable for concrete is adopted to predict this cracking strength. Various existing methods of predicting the cracking strength of pre-tensioned and post-tensioned I beams are compared with the present proposal.
Yield-line theory and plasticity
Authors: Clyde D. H. 
Published: July 2012

Synopsis In order to test a field solution for moment in a slab for uniqueness, it is necessary to use a compatibility condition. It is shown that this may be written by coupling the curvatures. The requirements for a field solution in which all elements are at the failure state are so restrictive that it is likely that discontinuous solutions such as are used in yield-line theory will be required in the majority of cases.
Non-linear analysis of reinforced concrete slabs
Authors: Bell J. C. , Elms D. G. 
Published: July 2012

Synopsis The paper describes the formation of a theoretical model which aims to describe the behaviour of a reinforced concrete slab throughout the whole of its loading range from initial loading to ultimate collapse. The model is based on the use of anisotropic finite elements, and a successive approximation technique. It synthesizes the section properties ofa slab from fundamental properties of the concrete and reinforcing steel. Moments, deflections and crack patterns are produced. The use of the model is illustrated by the analysis of a slab: the results of this analysis are compared with experimental results.
The stress-strain relationship for hardened cement pastes in compression
Authors: Spooner D. C. 
Published: July 2012

Synopsis Measurements of the stress-strain relationship of cement pastes of different water/cement ratios and various ages have been made at two strain rates. At the faster rate the maximum stress was attained after 1 to 2 h, whereas at the slower rate it was attained after 15 to 30 h. It is shown that the curvature of the stress-strain relationship can be partially explained by the time-dependent properties of the paste, and some evidence is presented which indicates that structural damage occurs in the paste before the ultimate stress is reached.
Measuring the fracture toughness of cement paste and mortar
Authors: Brown J. H. 
Published: July 2012

Synopsis This paper describes two methods that have been used to measure the effective fracture toughness of cement pastes and mortars. The first is a notched-beam technique, combined with compliance measurements to measure the slow crack growth prior to instability. The change of toughness is measured for separate increments of crack growth as the crack propagates. The second method, using a double-cantilever beam, avoids the slow crack growth problem by making a specimen of variable web width such that the length of crack front increases with and exactly compensates for the effect of crack growth. Tests of both pastes and mortars show that the fracture toughness of cement paste is independent of crack growth but that the toughness of mortar increases as the crack propagates. For both materials, the stress intensity required to initiate crack growth was less than that to maintain crack growth at the loading rates used.
Load-deflection characteristics of rectangular reinforced concrete slabs
Authors: Moy S. S. J. , Mayfield B. 
Published: July 2012

Synopsis This paper presents a method for predicting the deflections of reinforced concrete slabs from zero load to failure, taking account of the effect of the membrane forces produced by the slab flexure. A comparison is made between typical theoretical predictions and the results of a series of slab tests. In the light of this, the applicability of the method is then assessed.
Moment-curvature characteristics of prestressed concrete sections
Authors: Gupta B. K. , Edwards A. D. 
Published: July 2012

Synopsis Moment-curvature relationships, obtained from eight geometrically similar critical sections of four two-span post-tensioned beams and sixteen geometrically similar critical sections of four post-tensioned portal frames with fixed feet, are examined. Element and sectional behaviour is suggested that reasonably predicts the moment-curvature relationship of similar sections which occur at different points in the same structure.
Development of apparatus to investigate the influence of pore pressure upon the tensile behaviour of concrete
Authors: Elvery R. H. , Cox A. T. , Butler J. E. 
Published: July 2012

Synopsis This paper describes a method of testing concrete under water pore pressures which result in tensile failures. Details of the principles, construction of the apparatus and methods of operation are described. Typical experimental results of ultimate tensile failure are presented to indicate the reliability of the method.
Torsional stiffness of reinforced concrete members subjected to pure torsion
Authors: Karlsson Inge , Elfgren Lennart 
Published: July 2012

Synopsis A method is described for determining the torsional stiffness at the cracked stage of reinforced concrete members subjected to a pure torsional moment. The method is based upon a truss analogy for torsion. Theoretical expressions are deduced for the Torsional stiffness of beams of arbitrary and rectangular cross-sections. The theoretical values are compared with experimental results for rectangular beams. The applicability of the theory used is briefly discussed and a procedure is given to correct for its imperfections.
The effect of rate of loading upon the static and fatigue strengths of plain concrete in compression
Authors: Sparks P. R. , Menzies J. B. 
Published: July 2012

Synopsis The paper describes an experimental investigation into the effect of the rate of application of steadily increasing loads upon the static strength and of fluctuating loads upon the fatigue strength of plain concretes in compression. Concretes made with gravel, limestone or Lytag aggregate were tested. Increasing the rate of application of load was found, in general, to enhance the static strength andfatigue strength of all three types of concrete. The increase in static strength was found to be greatest in concrete with a relatively weak and soft aggregate such as Lytag and least in a concrete with relatively strong and stiff aggregate such as limestone. In the fatigue tests, a strong correlation was found between the rate of strain increase per cycle during most of the life of a specimen and the endurance of the specimen, irrespective of the rate of application of the load.
The effect of temperature change upon the creep of mortar under torsional loading
Authors: Illston J. M. , Sanders P. D. 
Published: July 2012

Synopsis Details are given of a novel test rig developed to investigate the creep of concrete under varying temperature. Tubes of saturated mortar were subjected to sustained torsional load, and the creep in shear was measured. The results showed that, when the temperature was raisedfor the first time, the creep rate increased greatly in comparison with that of a similar specimen heated before loading. No such change of rate was observed when the temperature was lowered or when it was raised to a level previously attained. It is shown that creep under variable temperature may be considered as the sum of three components: under constant temperature, flow (irrecoverable) and delayed elastic strain (recoverable); and as a result of the first temperature rise, transitional thermal creep (irrecoverable).