bluuebunny/crossref_metadata_2025_split huggingface dataset:
The compressive strength of concrete: a statistical approach to failure
Authors: Hobbs D. W. 
Published: July 2012

Synopsis An attempt is made to obtain a general expression for the dependence of the compressive strength of concrete cubes upon water/cement ratio, aggregate grading and aggregate volume concentration. It is assumed that the paste phase has a distribution of weaknesses which is represented by the Weibull distribution. It is shown that the deduced expression may, for certain conditions, be simplified to give Abrams's law. Some experimental results are given which enable the constants in the deduced expression to be obtained. It is suggested that strength calculations made from the resulting equation may be of some assistance in mix design.
Conditions for instability in restrained concrete panels exposed to fire
Authors: Dougill J. W. 
Published: July 2012

Synopsis The occurrence of instabilities associated with general spalling of plain concrete panels is investigated numerically for a thermal history that is similar to that obtained in a standard fire test. The results illustrate the effects of restraint and loading upon the incidence of general spalling. The behaviour of a heated panel is very much influenced by the extent of cracking, due to tensile stress, and by the steepness of the descending branch of the stress-strain curve in compression. The first of these effects may have important implications concerning the use of large quantities of reinforcing steel in heated panels. The second effect is more difficult to assess but it seems possihle that strain softening may be made more serious by the presence of a modest pore pressure in the concrete. The production of steam in the concrete at high temperatures could increase the possibility of the occurrence of general spalling in this way.
Detection of cracks in concrete by holography
Authors: Light M. F. , Luxmoore A. R. 
Published: July 2012

Synopsis Holographic interferometry has been used to detect hairline cracks in concrete, before normal visual detection was possible. The crack patterns on 100 mm test cubes under compression and 150 mm diameter cylinders under a diametral load have been studied, and it was possible to follow the propagation of these cracks up to failure.
The failure of glass-fIbre-reinforced notched beams in flexure
Authors: Brown J. H. 
Published: July 2012

Synopsis The resistance to crack propagation in glass-fibre-reinforced cement paste has been assessed by using a technique developed for measuring the fracture toughness of unreinforced cement pastes and mortars. The values measured with the fibrous material are not true toughness values but can be treated as such for small crack growths or used for relative assessment of the resistance to cracking over a larger range of growth. The material tested was an OPC/pfa matrix with chopped glass-fibre distributed at random. Three different mixes were used (0, 1·1% and 2·3% glassfibre volume fractions) tested 14, 28 and 84 days from casting. The pseudo-toughness of the fihre-reinforced material was no higher than that of the unreinforced matrix at the initiation of crack growth, but thereafter increased linearly with crack growth at a rate proportional to the fibre content. The change of toughness for crack growths up to 12 mm could be measured; at this point, the 2·3% fibre content gave about 5 and the 1·1% content ahout 3 times the toughness of the matrix material, and the toughness was still increasing with crack growth. The psuedo-toughness was not affected by age up to 84 days from mixing.
Apparatus for compression tests on concrete at high temperatures
Authors: Purkiss J. A. , Dougill J. W. 
Published: July 2012

Synopsis Apparatus comprising a special machine and furnace is descrihed which enables tests involving high-temperature exposure and compressive loading or restraint to be undertaken on small concrete specimens. Details of the instrumentation and proving tests are given, together with sample results for the stress-strain curve of concrete in compression at high temperatures and some data concerning relaxation of stress under conditions of constant strain.
The effect of aggregate shape upon the strength of structural lightweight-aggregate concrete
Authors: Czuryszkiewicz Andrzej 
Published: July 2012

Synopsis The influence of the shape of a lightweight aggregate (a sintered fly-ash) upon the compressive strength of lightweight-aggregate concrete is described. The effective strength of the lightweight aggregate was calculated by extrapolation from the Bache-Christensen model. It is shown that: (a) the compressive strength of lightweight-aggregate concrete depends upon the shape of the aggregate particles—the concrete tested with rounded aggregate (n = 0·40) had a compressive strength about 6 to 8 N/mm2 greater than those with elongated form (length/thickness ratio 4·0); (b) the effective strength of lightweight aggregate depends upon the shape of the aggregate particles—the rounded aggregate particles used had a strength of approximately 25·0 N/mm2 and the elongated had strengths of approximately 17·5 N/mm2 and 20·0 N/mm2 for length/thickness ratios of 4 and 2 respectively.
Fibrous structure in a hardened cement paste
Authors: Ball M. C. , Stapleton G. , Raffle J. F. 
Published: July 2012

Synopsis Some pastes and mortars when thoroughly dry have high electrical insulation resistance. During studies on methods of winding coils, pastes of ordinary Portland cement and ethylene glycol were investigated. When such pastes are heated, the solvent partially evaporates, leaving a strong, rigid, porous solid which on subsequent hydration absorbs some 25% of water and increases further in strength. Scanning electron-micrographs show that this material consists of a mass of interlinking fibrous crystals—a completely different morphology from that seen in normal hydrated pastes.
A stress-strain relationship for concrete at high temperatures
Authors: Baldwin R. , North M. A. 
Published: July 2012

Synopsis This paper reviews some data on the effects of temperature (up to 7000°C) upon the relationship between stress and strain for concrete under compression. It is shown that the effects of temperature can be represented by an equation of the form σ/σmax = f(ϵ/ϵmax), where f is a functional form independent of temperature, and σmax and ϵmax are the values of stress and strain at the point of maximum stress, which vary with temperature. This scaling law is used to derive a relationship for the variation of the modulus of elasticity with temperature.
Mechanical properties of cement mortar with randomly oriented short steel wires
Authors: Pakotiprapha B. , Pama R. P. , Lee S. L. 
Published: July 2012

Synopsis This paper deals with an analytical and experimental investigation of the mechanical properties of cement mortar reinforced with randomly oriented short steel wires. Analytically, the material is treated as a composite and its properties are derived by the laws of mixture. The effect of random orientation of the short wires is taken into consideration by the introduction of dimensionless factors which are derived on the assumption that the geometric centres of the wires are uniformly distributed in space and that any wire has an equal probability of being oriented at any angle to the direction of the applied stress. Explicit expressions are given for the moduli of elasticity and the ultimate strengths in tension and compression. In bending and torsion, the composite is idealized as a bi-linear material to describe its behaviour in the uncracked and in the cracked range provided that the volume fraction and the length of wires used exceed certain values which are suggested. Experiments were conducted and the results obtained are shown to be in good agreement with theoretically predicted values.
The influence of shear upon the deformation of reinforced concrete beams at ultimate load
Authors: Johnston B. 
Published: July 2012

Synopsis An experimental and theoretical investigation of the deformation of reinforced concrete beams subject to high moment and shear is presented. It is shown that under certain conditions the conventionalflexural theory does not predict the actual behaviour of the beams and that at ultimate load a concentration of rotation into the hinge length can be expected.
The application of rate theory to time-dependent deformation of concrete
Authors: Wittmann F. H. , Lukas J. 
Published: July 2012

Synopsis On the basis of rate theory aformula is derived which describes creep of concrete under sealed and drying conditions. A series of exponential expressions is introduced for the time dependence of shrinkage. Small specimens of hardened cement paste were tested under sealed conditions at 90% R.H. and 53% R.H. Creep was also determined on specimens equilibrated at 90% R.H. but tested at 53% R.H. Similar experiments were carried out on hollow cylinders of hardened cement paste. The observed behaviour could be satisfactorily described with the help of the derived formula. The validity of the equation and some advantages of its application are further established by a critical comparison with suitable concrete creep data in the literature. Possible extensions and further applications of the approach are discussed.
A rational theory for balanced failure of prestressed concrete beams in torsion and bending
Authors: Below K. D. , Rangan B. V. , Hall A. S. 
Published: July 2012

Synopsis This paper presents a rational theory for the prediction of the steel quantities required for a fully or partially balanced failure of a prestressed concrete beam of rectangular section subjected to combined bending and torsion. The theory is based on the general theory given in an earlier paper. An interaction diagram is presented which shows the steel strains at failure as a function of the steel quantities. The influence of some parameters upon the steel quantities required for a fully balanced failure is also examined.
Lines of discontinuity for displacements in the theory of plasticity of plain and reinforced concrete
Authors: Jensen Bjarne Chr. 
Published: July 2012

Synopsis The internal plastic work in a line of discontinuity for displacements is calculated for a material that obeys Coulomb's modified yield criterion. This is then usedfor the determination of the carrying capacity of a number of selected examples of plain and reinforced concrete. Good agreement is found between theory and tests in respect of the selected examples. The application of discontinuity lines in concrete thus means an extension of the possibilities for plastic analysis of plain and, particularly, reinforced concrete.
Failure of concrete under sustained tension
Authors: Al-Kubaisy M. A. , Young A. G. 
Published: July 2012

Synopsis The mechanism of cracking in concrete under sustained axial tension is investigated experimentally. This involves the development of new loading and measuring techniques: in particular, the development of a specimen with shoulder-pieces composed of high alumina cement concrete which permits the direct transmission of ultrasonic pulses along the longitudinal axis. Observations indicate that cracks form in the concrete at an early stage of loading at interfaces between the cement matrix and aggregate but that failure is governed by the growth of cracks within the cement matrix. The results are used to establish a law relating sustained stress to time to rupture, which may prove to be of value in analysing the behaviour of more complex structures under sustained load.
Distortional bending in the web of prestressed concrete beams
Authors: Swann R. A. 
Published: July 2012

Synopsis Present design practice for dealing with distortional bending in the webs of prestressed concrete box beams is to superimpose a conventional design for transverse bending of the web upon the regime required for vertical shear and bending. This procedure has not been verified experimentally and this paper gives brief details of tests on four specimens specially designed to cover a wide range of practical cases. The results confirm that the proposed simple design procedure is satisfactory for medium and heavy shear and for a wide range of transverse bending moments. The limitations of the test programme are clearly defined and proposals are made for future research.
An inexact Gauss-Newton method for inversion of basal sliding and rheology parameters in a nonlinear Stokes ice sheet model
Authors: Petrat Noemi , Zhu Hongyu , Stadler Georg , Hughes Thomas J.R. , Ghattas Omar 
Published: July 2012

AbstractWe propose an infinite-dimensional adjoint-based inexact Gauss-Newton method for the solution of inverse problems governed by Stokes models of ice sheet flow with nonlinear rheology and sliding law. The method is applied to infer the basal sliding coefficient and the rheological exponent parameter fields from surface velocities. The inverse problem is formulated as a nonlinear least-squares optimization problem whose cost functional is the misfit between surface velocity observations and model predictions. A Tikhonov regularization term is added to the cost functional to render the problem well-posed and account for observational error. Our findings show that the inexact Newton method is significantly more efficient than the nonlinear conjugate gradient method and that the number of Stokes solutions required to solve the inverse problem is insensitive to the number of inversion parameters. The results also show that the reconstructions of the basal sliding coefficient converge to the exact sliding coefficient as the observation error (here, the noise added to synthetic observations) decreases, and that a nonlinear rheology makes the reconstruction of the basal sliding coefficient more difficult. For the inversion of the rheology exponent field, we find that horizontally constant or smoothly varying parameter fields can be reconstructed satisfactorily from noisy observations.
ICOS Mediates the Generation and Function of CD4+CD25+Foxp3+ Regulatory T Cells Conveying Respiratory Tolerance
Authors: Busse Mandy , Krech Mathias , Meyer-Bahlburg Almut , Hennig Christian , Hansen Gesine 
Published: July 2012

Abstract
Costimulatory molecules like ICOS are crucial in mediating T cell differentiation and function after allergen contact and thereby strongly affect the immunologic decision between tolerance or allergy development. In this study, we show in two independent approaches that interruption of the ICOS signaling pathway by application of a blocking anti-ICOSL mAb in wild-type (WT) mice and in ICOS−/− mice inhibited respiratory tolerance development leading to eosinophilic airway inflammation, mucus hypersecretion, and Th2 cytokine production in response to OVA sensitization. Respiratory Ag application almost doubled the number of CD4+Foxp3+ regulatory T cells (Tregs) in the lung of WT mice with 77% of lung-derived Tregs expressing ICOS. In contrast, in ICOS−/− mice the number of CD4+CD25+Foxp3+ Tregs did not increase after respiratory Ag application, and ICOS−/− Tregs produced significantly lower amounts of IL-10 than those of WT Tregs. Most importantly, in contrast to WT Tregs, ICOS−/− Tregs did not convey protection when transferred to “asthmatic” recipients demonstrating a strongly impaired Treg function in the absence of ICOS signaling. Our findings demonstrate a crucial role of ICOS for the generation and suppressive function of Tregs conveying respiratory tolerance and support the importance of ICOS as a target for primary prevention strategies.
Endothelial CD47 Promotes Vascular Endothelial-Cadherin Tyrosine Phosphorylation and Participates in T Cell Recruitment at Sites of Inflammation In Vivo
Authors: Azcutia Veronica , Stefanidakis Michael , Tsuboi Naotake , Mayadas Tanya , Croce Kevin J. , Fukuda Daiju , Aikawa Masanori , Newton Gail , Luscinskas Francis W. 
Published: July 2012

Abstract
At sites of inflammation, endothelial adhesion molecules bind leukocytes and transmit signals required for transendothelial migration (TEM). We previously reported that adhesive interactions between endothelial cell CD47 and leukocyte signal regulatory protein γ (SIRPγ) regulate human T cell TEM. The role of endothelial CD47 in T cell TEM in vivo, however, has not been explored. In this study, CD47−/− mice showed reduced recruitment of blood T cells as well as neutrophils and monocytes in a dermal air pouch model of TNF-α–induced inflammation. Reconstitution of CD47−/− mice with wild-type bone marrow cells did not restore leukocyte recruitment to the air pouch, indicating a role for endothelial CD47. The defect in leukocyte TEM in the CD47−/− endothelium was corroborated by intravital microscopy of inflamed cremaster muscle microcirculation in bone marrow chimera mice. In an in vitro human system, CD47 on both HUVEC and T cells was required for TEM. Although previous studies showed CD47-dependent signaling required Gαi-coupled pathways, this was not the case for endothelial CD47 because pertussis toxin, which inactivates Gαi, had no inhibitory effect, whereas Gαi was required by the T cell for TEM. We next investigated the endothelial CD47-dependent signaling events that accompany leukocyte TEM. Ab-induced cross-linking of CD47 revealed robust actin cytoskeleton reorganization and Src- and Pyk-2–kinase dependent tyrosine phosphorylation of the vascular endothelial-cadherin cytoplasmic tail. This signaling was pertussis toxin insensitive, suggesting that endothelial CD47 signaling is independent of Gαi. These findings suggest that engagement of endothelial CD47 by its ligands triggers outside-in signals in endothelium that facilitate leukocyte TEM.
A Genetically Encoded IL-1β Bioluminescence Resonance Energy Transfer Sensor To Monitor Inflammasome Activity
Authors: Compan Vincent , Baroja-Mazo Alberto , Bragg Laricia , Verkhratsky Alexei , Perroy Julie , Pelegrin Pablo 
Published: July 2012

Abstract
Inflammation is fundamental for protecting the organism against infection and injury. However, a failure to control immune response results in chronic inflammation and several associated disorders such as pain and loss of function. Initiation of inflammation is orchestrated by cytokines, among which IL-1β is particularly important. IL-1β is synthesized as an inactive protein that has to be processed by the inflammasome to generate the mature bioactive form. Conventional techniques cannot monitor IL-1β activation with high spatial and temporal resolution. In this study, we present a ratiometric biosensor that allows monitoring IL-1β processing in real time, with a temporal resolution of seconds and with a single-cell spatial resolution. Using this sensor, to our knowledge, we describe for the first time the kinetic of the inflammasome activity in living macrophages. With this new probe, we also demonstrated that the pro–IL-1β processing occurs all over the cytoplasm.
A Case of Empyema Thoracic due to Salmonella typhi in 18-month-old Child: An Unusual Cause
Authors: Nandan Devki , Jhavar Lalish , Dewan Vivek , Bhatt Girish Chandra , Kaur Nirmaljeet 
Published: July 2012

ABSTRACTWe herein report an 18-months-old child who presented with high-grade fever, cough, and breathlessness along with tachypnoea and diminished air entry on the left side of the chest, in which a diagnosis of left-sided pleural effusion was made. Salmonella typhi was isolated from the pleural tap culture. The patient had uneventful recovery with appropriate antibiotic therapy. Empyema thoracic as a complication is extremely rare in the absence of an underlying co-morbid illness, is even more uncommon in a child, and is even rarer to find with Salmonella typhi species. After reviewing the available literature we could find only five cases of empyema thoracic due to Salmonella typhi in children with the age range of 9–13 years. We are reporting this case as the youngest child reported with this complication.
Country Inequality Rankings and Conversion Schemes
Authors: Schröder Carsten , Bönke Timm 
Published: July 2012

Abstract
Two conversion schemes may be employed for assessing income inequality from household equivalent incomes: to weight household units by size or by needs. Using data from the Luxembourg Income Study, we show the sensitivity of country inequality rankings to conversion schemes and explain the finding by means of inequality decomposition. A bootstrap approach is implemented to test for statistical significance of our results.
Downsizing is dead; long live the downsizing phenomenon: Conceptualizing the phases of cost-cutting
Authors: Gandolfi Franco , Littler Craig R 
Published: July 2012

AbstractDownsizing as a systematic reduction of employees is frequently utilized in order to increase productivity, efficiency, profitability, and competitiveness of organizations. As a strategy of choice for many firms around the world, downsizing produces far-reaching financial, organizational, and social consequences. Despite the large body of literature, there is inconclusive evidence as to whether downsizing is effective and whether it generates the widely anticipated benefits. Employee downsizing as a change management strategy has been actively adopted for more than three decades. This downsizing article presents a phase typology of job cutting including three distinct phases and three levels of argument. As a conceptual paper, it aims to examine, update, and extend Littler and Gandolfi's (2008) seminal work. The research paper culminates with a discussion of current downsizing practices, and posits that the downsizing phenomenon has remained a popular restructuring.
Financial turning points and transitions for people with multiple sclerosis: Towards sustainable employment outcomes
Authors: Vickers Margaret H 
Published: July 2012

AbstractPeople with disability experience significant levels of economic disadvantage potentially resulting in their poverty, social exclusion and dependence on welfare. Low labour participation rates are a large contributor to such economic and social exclusion. This study was conducted in Australia where 45% of people with disability are living at or below the poverty line. Within this context, this article first defines and examines the constructs of Financial Turning Points and Financial Transitions experienced by people with disability, an area not previously examined in the literature. Then, a collective case study is presented portraying the experiences of Financial Turning Points and Financial Transitions for people with multiple sclerosis (MS). Concluding remarks are directed towards the need to critically re-evaluate ways of thinking about work to enable people with disability to remain productive participants in employment, to better facilitate of their financial futures.