bluuebunny/crossref_metadata_2025 huggingface dataset:
An Empirical Test of Low Self-Control Theory
Authors: Vera Eliseo P. , Moon Byongook
Published: July 2012

This study, using a sample of 277 Hispanic youth, examines the generality of Gottfredson and Hirschi’s general theory of crime in explaining the etiology of delinquency among Hispanic juveniles, especially focusing on the relationships among parental practices, low self-control, and deviant behaviors. The results indicate that low self-control is significantly related to general deviant behaviors, consistent with the theory’s prediction. However, the findings show that the theoretically informed measures of parental practices are not significantly related to child levels of self-control. Instead, individual’s perception toward levels of community disorder has a significant effect on child levels of self-control. Theoretical implications as well as limitations of the findings are discussed.
Crime, media and the will-to-representation: Reconsidering relationships in the new media age
Authors: Yar Majid
Published: July 2012

This paper considers the ways in which the rise of new media might challenge commonplace criminological assumptions about the crime–media interface. Established debates around crime and media have long been based upon a fairly clear demarcation between production and consumption, between object and audience – the media generates and transmits representations of crime, and audiences engage with them. However, one of the most noticeable changes occurring in the wake of the development of new media is the proliferation of self-organised production by ‘ordinary people’ – everything ranging from self-authored web pages and ‘blogs’, to self-produced video created using hand-held camcorders, camera-phones and ‘webcams’. Today we see the spectacle of people performing acts of crime and deviance in order to record them, send them and upload them to the Internet. This kind of ‘will to representation’ may be seen in itself as a new kind of causal inducement to law- and rule-breaking behaviour. It may be that, in the new media age, the terms of criminological questioning need to be sometimes reversed: instead of asking whether ‘media’ instigates crime or fear of crime, we must ask how the very possibility of mediating oneself to an audience through self-representation might be bound up with the genesis of criminal behaviour.
Ruin porn, documentary, and metal theft: An interview with the co-directors of Scrappers
Authors: Ashby Brian , Kolak Ben , Prokopas Courtney , Whiteacre Kevin
Published: July 2012

The documentary film Scrappers, co-directed by Brian Ashby, Ben Kolak, and Courtney Prokopas, is a vérité portrait of Oscar and Otis, two metal scavengers who “search for a living with brains, brawn and battered pickup trucks.” The film encompasses several emerging themes bearing on contemporary crime, media, and culture, including the growing popularity of an American post-industrial aesthetic, the blurring distinction between film—particularly documentary—and social science, and the recent trend of metal theft, which has risen as one of the most prevalent property crimes in the first decade of the 21st century. This interview with the co-directors elaborates on these themes.
Addiction to c-MYC in multiple myeloma
Authors: Holien Toril , Våtsveen Thea Kristin , Hella Hanne , Waage Anders , Sundan Anders
Published: July 2012

In multiple myeloma, c-MYC is activated and contributes to the malignant phenotype. Targeting MYC by short hairpin RNA induced cell death in myeloma cell lines; however, cell lines are generated from samples taken in advanced stages of the disease and may not reflect patient cells adequately. In this study, we used the selective small molecule inhibitor of MYC-MAX heterodimerization, 10058-F4, on myeloma cell lines as well as primary myeloma cells, and we show that inhibition of c-MYC activity efficiently induces myeloma cell death. Moreover, in cocultures of cell lines with bone marrow stromal cells from myeloma patients, the inhibitor still induces apoptosis. Our results provide further evidence that myeloma cells are addicted to c-MYC activity and that c-MYC is a promising therapeutic target in multiple myeloma.
Biochemical tolerance during low dose propylene glycol exposure in neonates: A formulation-controlled evaluation
Authors: Kulo Aida , Smits Anne , Naulaers Gunnar , de Hoon Jan , Allegaert Karel
Published: July 2012

Background and purpose of the study

Propylene glycol (PG) is a frequently co-administered solvent in formulations administered to neonates, but reports on its (in)tolerance are limited. We aimed to report on renal, metabolic and hepatic tolerance before, during and following intravenous (iv) PG-paracetamol exposure and compared these data with similar datasets reported in literature on neonates exposed to PG without paracetamol or paracetamol without PG.

Methods

Renal (diuresis, creatinemia, sodium), metabolic (Base Excess, Anion Gap, lactate, bicarbonate) and hepatic (liver enzymes, bilirubinemia) indicators before, during and following iv paracetamol-PG exposure in neonates as included in the PARANEO (paracetamol inneonates) study (intra-individual trends, ANOVA) were collected and analysed. Comparison with observations collected in cases exposed to either iv phenobarbital-PG or iv paracetamol-mannitol (inter-individual comparison, Mann Whitney-Utest) were made.

Results

PG exposure (median 34.1 mg/kg/24 h) did not affect postnatal renal, metabolic and hepatic adaptations in 60 cases exposed to paracetamol-PG. These indicators were similar when compared to 29 cases exposed to phenobarbital-PG or 172 cases exposed to paracetamol-mannitol.

Major conclusion

Based on observations in 89 neonates, low dose PG exposure was tolerated well. Studies on PG pharmacokinetics and its covariates are needed to estimate the upper level of PG tolerance in neonates.
Generalized diamond-α dynamic opial inequalities
Authors: Atasever Nuriye , Kaymakçalan Billûr , Lešaja Goran , Taş Kenan
Published: July 2012

We establish some new dynamic Opial-type diamond alpha inequalities in time scales. Our results in special cases yield some of the recent results on Opial's inequality and also provide new estimates on inequalities of this type. Also, we introduce an example to illustrate our result.

Mathematics Subject Classification 2000: 39A12; 26D15; 49K05
Multi-view alignment with database of features for an improved usage of high-end 3D scanners
Authors: Bonarrigo Francesco , Signoroni Alberto , Leonardi Riccardo
Published: July 2012

The usability of high-precision and high-resolution 3D scanners is of crucial importance due to the increasing demand of 3D data in both professional and general-purpose applications. Simplified, intuitive and rapid object modeling requires effective and automated alignment pipelines capable to trace back each independently acquired range image of the scanned object into a common reference system. To this end, we propose a reliable and fast feature-based multiple-view alignment pipeline that allows interactive registration of multiple views according to an unchained acquisition procedure. A robust alignment of each new view is estimated with respect to the previously aligned data through fast extraction, representation and matching of feature points detected in overlapping areas from different views. The proposed pipeline guarantees a highly reliable alignment of dense range image datasets on a variety of objects in few seconds per million of points.
End-of-Life Care at a Community Cancer Center
Authors: Cowall David E. , Yu Bennett W. , Heineken Sandra L. , Lewis Elizabeth N. , Chaudhry Vishal , Daugherty Joan M.
Published: July 2012

Early concurrent palliative care and earlier hospice admission may improve quality of life because of better symptom management and avoidance of aggressive and/or toxic therapies at end of life.
From Human Tissue to Human Bodies: donation, interventions and justified distinctions?
Authors: Quigley Muireann
Published: July 2012

This article reviews the latest report from the Nuffield Council on Bioethics, Human Bodies: Donation for Medicine and Research. It argues that the report represents a notable evolution in the Council's position regarding the appropriate governance of the human body and biomaterials. It then goes on to examine in more depth one of the report's recommendations – that a pilot payment scheme for eggs for research purposes should be trialled. In particular, it looks at whether the distinctions drawn, first, between eggs for research and therapeutic purposes and, secondly, between eggs for research and other biomaterials can be adequately justified.
Compressibility characteristics of tropical peat using Rowe cell consolidation
Authors: Kolay P. , Sii H. , Taib S.
Published: July 2012

This paper presents the results of the physical and compressibility characteristics of tropical peat, from Matang, Malaysia. Different physical properties tests have been conducted on peat samples. Rowe cell consolidation and standard 1-D consolidation tests were performed on undisturbed peat samples to evaluate the compressibility characteristics. A specially designed and fabricated peat sampler has been used to collect the undisturbed peat sample for Rowe cell consolidation test. The laboratory test results revealed that peat has a large void ratio with high water content and undergone large consolidation settlements when applied load. The results of Rowe cell test can be used to simulate close to the the field geotechnical characteristics of peat for any design or numerical modelling where reliable data is most important.
EHD dispersion of atmospheric aerosols through a vertical channel with temperature distributions
Authors: Meena Priya , Nirmala P.
Published: July 2012

The electrohydrodynamic (EHD) dispersion of atmospheric aerosols consisting of a couple stress fluid through a vertical channel, when the walls are held at different temperatures is studied by using Taylor dispersion model. Analytical solutions for the nonlinear coupled equations are obtained using a regular perturbation technique (RPT) with buoyancy number, N(<<1) as the perturbation parameter. The effect of electric field and couple stress parameter on velocity, temperature and dispersion of aerosols are numerically computed and the results are represented graphically.
Study of tribological performance of selected thermal sprayed polymers
Authors: Lima C. , Siqueira L. , Camargo F.
Published: July 2012

Thermal spray processes have a broad application in both manufacturing and maintenance. Thermal spray is a group of processes in which metallic and nonmetallic materials, finely divided, are deposited on a prepared substrate forming a sprayed deposit. Many metals, ceramics, intermetallic compounds, some organic and some plastic glasses can be deposited by one or more of the various thermal spray techniques. Nowadays, thermal spray technology is of great importance in the search for engineering solutions to the increasing demands on technical and economic aspects of the industries in general. At the scene of a great variety of options it is fundamental to take into account the economic variables and productivity that often overlap pure technical solution. Thus, the study of deposition methods and material options for the same application becomes extremely relevant and timely. Polymer coatings have great potential to improve the performance of surfaces of light or heavy metals. The main objective of this work was to study the properties of thermal sprayed polymer coatings looking for the possibilities of applying this type of coating for tribological demand. From the obtained results, there is strong evidence that the use of flame sprayed polymer powders, mainly PEEK, with substrate preheating would have a good performance in wear and corrosion applications.
Family Environment and Behavior Problems in Children, Adolescents, and Adults with Fragile X Syndrome
Authors: Greenberg Jan S. , Seltzer Marsha Mailick , Baker Jason K. , Smith Leann E. , F. Warren Steven , Brady Nancy , Hong Jinkuk
Published: July 2012

We examine how the family environment is associated with aspects of the Fragile X syndrome phenotype during childhood, adolescence, and adulthood. Mothers of children (n  =  48), adolescents (n  =  85), and adults (n  =  34) with Fragile X syndrome participated in a multisite study. For children and adults with Fragile X syndrome, the presence of warmth and positivity and the absence of criticism were associated with fewer behavior problems. Although a higher level of criticism was significantly associated with greater behavior problems, there were only trend-level associations between levels of warmth and positivity and behavior problems during the adolescent years. The provision of family psychoeducation programs, which can reduce parental criticism, would likely benefit both the individual with Fragile X syndrome and the family.
Misresponse to Reversed and Negated Items in Surveys: A Review
Authors: Weijters Bert , Baumgartner Hans
Published: July 2012

There are important advantages to including reversed items in questionnaires (e.g., control of acquiescence, disruption of nonsubstantive responding, better coverage of the domain of content of a construct), but reversed items can also lead to measurement problems (e.g., low measure reliability, complex factor structures). The authors advocate the continued use of reversed items in measurement instruments but also argue that they should be used with caution. To help researchers improve their scale construction practices, the authors provide a comprehensive review of the literature on reversed and negated items and offer recommendations about their use in questionnaires. The theoretical discussion is supplemented with data on 1330 items from measurement scales that have appeared in Journal of Marketing Research and Journal of Consumer Research.
Der Auftakt zur Verfolgung der Juden in Frankreich 1940
Authors: Bruttmann Tal , Joly Laurent , Lambauer Barbara
Published: July 2012

Vorspann

Der Holocaust war ein deutsches Projekt. Er wurde von Deutschen initiiert und vorangetrieben, aber er fand in ganz Europa erschreckend viel Sympathie, auch in Frankreich, wo sich nach dem deutschen Sieg die Vichy-Regierung klar und fast ohne deutsches Zutun für eine antisemitische Politik entschied. So lautete, knapp gefasst, die These, die Michael Mayer vor kurzem in den Vierteljahrsheften (Juli 2010) vertrat. Diese These hat nicht nur Zustimmung gefunden. War der deutsche Einfluss auf Vichy-Frankreich nicht doch viel größer, als es Mayer vermutet?
Eficiência de uso de nitrogênio em cobertura pelo feijoeiro irrigado
Authors: Sant'Ana Edvaldo V. P. , Santos Alberto B. dos , Silveira Pedro M. da
Published: July 2012

Entre as técnicas de manejo necessárias para atingir alto potencial produtivo nos sistemas agrícolas irrigados, está a adubação nitrogenada. O objetivo deste trabalho foi avaliar os efeitos de doses de nitrogênio aplicadas em cobertura sobre a fitomassa e a eficiência de uso do nutriente pela cultivar BRS Horizonte de feijoeiro. O experimento foi conduzido na Embrapa Arroz e Feijão, em um Latossolo Vermelho distrófico, em delineamento experimental de blocos ao acaso, com quatro repetições e cinco doses de nitrogênio, 0, 30, 60, 120 e 240 kg ha-1, na forma de uréia, aplicadas em cobertura metade aos dez dias após a emergência (DAE) e a outra metade aos 17 DAE. A fitomassa no florescimento do feijoeiro relacionou-se linearmente com as doses de N aplicadas em cobertura, ao passo que a fitomassa na colheita apresentou resposta quadrática. As relações entre o índice de colheita de grãos e o índice de colheita de N com as doses de N foram quadráticas e os índices máximos foram estimados com a dose de 140 kg ha-1 de N. A eficiência de uso de nitrogênio pelo feijoeiro variou com as doses de N aplicadas e com o tipo de eficiência calculada, enquanto as eficiências agronômica e fisiológica diminuíram com o incremento da dose.
Sustainable This, Sustainable That: New Materialisms, Posthumanism, and Unknown Futures
Authors: Alaimo Stacy
Published: July 2012

mornings in the unknown future. Who shall repair this now. And how the future

takes shape

too quickly. The permanent is ebbing. Is leaving

—Jorie Graham, “Sea Change”

Conserving This, Conserving That

Just a few lines from jorie graham's poem “sea change” evoke anxiety about unpredictable futures that arrive too soon, in need of repair. The abrupt departure of a sense of permanence may provoke the desire to arrest change, to shore up solidity, to make things, systems, standards of living “sustainable.” Having worked in the environmental humanities and in science studies for the last decade and having served as the academic cochair of the University Sustainability Committee at the University of Texas, Arlington, for several years, I have been struck by how the discourse of sustainability at the turn of the twenty-first century in the United States echoes the discourse of conservation at the turn of the twentieth century, especially in its tendency to render the lively world a storehouse of supplies for the elite. Gifford Pinchot, Theodore Roosevelt's head of forestry, defined forests as “manufacturing plants for wood,” epitomizing the utilitarianism of the conservation movement of the Progressive era, which saw nature as a resource for human use. By the early twentieth century Pinchot's deadening conception of nature jostled with other ideas, such as those of aesthetic conservation and the fledgling science of ecology. Pinchot was joined by the Progressive women conservationists, who claimed, as part of the broader “municipal housekeeping” movement, that women had special domestic talents for conservation, such as “turning yesterday's roast into tomorrow's hash.” Many Progressive women conservationists not only bolstered traditional gender roles but also wove classism and racism into their conservation mission, as conservation became bound up with conserving their own privileges. The anthropocentrism of the Progressive women conservationists is notable. As a participant in the First National Conservation Congress stated in 1909, “Why do we care about forests and streams? Because of the children who are to be naked and bare and poor without them in the years to come unless you men of this great conservation work do well your work.” During their conventions the discourse of conservation was playfully and not so playfully extended to myriad causes, including conserving food, conserving the home, conserving morals, conserving “true womanliness,” conserving “the race,” conserving “the farmer's wife,” and conserving time by omitting a speech (Alaimo,Undomesticated Ground63–70).
The Letter of Richard Wyche: An Interrogation Narrative
Authors: Wyche Richard , Bradley Christopher G.
Published: July 2012

The dissident priest Richard Wyche, Judged a recalcitrant heretic by the church and condemned to die at the hands of the state, was burned at the stake in London in 1440. Almost four decades earlier, he had been interrogated by ecclesiastical officials in Durham. A record of his ordeal survives, extraordinarily, in the autobiographical narrative translated below.
The question of structural form: educational aspects
Authors: Lewis Wanda J.
Published: July 2012

Numerous examples of structural failures all over the world show that over-reliance on codes of practice in the process of design, or a high degree of trust placed in computational modelling, with its results not checked independently, carry an increased safety risk. While codes of practice provide strict guidance to designers, they do not shelter them from responsibility for the structural safety, function and durability aspects of their designs. Underpinning all these factors is the question of a good understanding of structural action, which depends on a good understanding of applied forces, the choice of structural form and material. Often, as a result of the primacy awarded to architectural vision, structurally ill-conceived designs may remain unmodified, even if they carry the potential for failure. Case studies presented here highlight this problem, indicating that the question of structural form should be as important to an engineer as it is to an architect.
An apparatus for measuring dimensional changes in fresh cement paste
Authors: Cromarty R. E. , Bryden J. G.
Published: July 2012

Summary

The apparatus described measures length changes in fresh cement paste to an accuracy of one part in two thousand. The calibration may readily be checked at the end of each measurement by a micrometer which forms part of the apparatus. The cement paste specimen floats on mercury and is thus subject to low restraining forces. The displacement is measured by a linear variable-differential transformer and the temperature of the paste is measured by a thermistor. These variables are recorded continuously on a two-channel strip chart recorder. Curing conditions can be pre-set or varied during an experiment. Data are presented showing dimensional and temperature changes in an ordinary Portland cement.
A new approach to the yield criterion for isotropically reinforced concrete slabs
Authors: Prince M. R. , Kemp K. O.
Published: July 2012

Summary

An expression based upon strain compatibility considerations is formulated for the normal moment of resistance across a yield line. Experiments are described which were designed to test this theory, and the results are shown to be consistent with its requirements. A method of incorporating the expression for normal moment into a generalized yield criterion is presented. The square yield criterion is found to be a lower bound on the yield criterion obtained and is approached as the ratio of crack width to bar diameter increases.
A study of bond between steel and restrained expanding concrete
Authors: Brown Colin B. , Szabo Zoltan S.
Published: July 2012

Summary

A critical professional question which may arise with the commercial availability of expanding concrete concerns the ability to reinforce the concrete with steel bars. In particular the bond phenomena are open to conjecture. These phenomena are studied here by means of tests which have previously indicated the characteristics of bond failure in ordinary concrete. Such tests indicate the bond mechanism between expanding concrete, properly restrained from radial motion, and an undeformed reinforcing bar. Comparisons with the ordinary concrete case are made and a discussion of the practical aspects of the problem is given.
An electron-microscope study of the contact between aggregate and hardened cement paste
Authors: Stork J. , Michálková B.
Published: July 2012

Summary

Two variations of a method of making two-stage replicas have been developed for studying in the first instance the contact between aggregate and hardened cement paste. The method, known as the impression method, requires about 15 min to make one replica without destruction of the specimen. The study was made on ‘model’ concrete (which is described) to eliminate the effect of impurities and sand. The principal aim of the paper is to give information on the newly developed method but, in addition, an attempt is made to give a morphological interpretation of the contact phenomena and to discuss certain difficulties complicating this kind of study.
The effect of mix proportions and aggregate dust upon the compressive strength of concrete
Authors: Hughes B. P. , Ash J. E.
Published: July 2012

Summary

The compressive strength of concrete at a constant cement/water ratio is shown to decrease with increasing cement contents and therefore confirms earlier work in Europe. This decrease, however, is generally quite small especially for the uniaxial compressive strength. Two exceptions are possible, depending upon the sand content: at high sand contents a critical maximum sand/cement ratio is exceeded such that air voids become unavoidable and the strength decreases with decreasing cement content; at low sand contents a critical minimum sand/cement ratio is not attained and large losses in strength then occur with increasing cement contents. The critical minimum sand/cement ratio depends upon the type and grading of the aggregate and the mix proportions. It is due to the onset of very extensive ‘water gain’ and to the lack of adequate restraint to shrinkage of the cement paste. These effects can (and should) be avoided in normal concretes. The presence of dust in the fine aggregate can be beneficial.for low-strength concretes probably because of its ability to modify the structure o.fthe cement paste and reduce the water gain. It has little effect on high-strength concretes.
An electrical measurement of the effective cross-sectional area for conduction or flow processes in cement paste
Authors: Hancox N. L.
Published: July 2012

Summary

The effective cross-sectional area for conduction or liquid flow processes in a porous material is not usually equal to the porosity ɸ but to ɸm where m is greater than 1. A simple way of obtaining ɸm is described and measurements are reported for saturated ordinary and high alumina cement paste specimens with water/cement ratios of 0·28 and 0·5 cured for between 1 and 28 days, and partially saturated specimens 35 days old. The results are used to calculate the mean pore radius in cement paste with a water/cement ratio of 0·5, and to determine the contribution of vapour diffusion to moisture movement in ordinary Portland cement paste drying between 50 and 95°C. It was found that, even at a low evaporable moisture content of 10%, mechanisms other than vapour diffusion are causing moisture transfer.
Photo-elastic analysis of shrinkage micro cracking in concrete
Authors: Theocaris P. S. , Koufopoulos T.
Published: July 2012

Synopsis

The paper deals with the stress distribution in concrete during the variations in volume due to hydration of the cement paste at early ages. A two-dimensional model was devised for the photo-elastic study of the stress distribution. The model consisted of a square array of circular inclusions made of pure epoxy polymer embedded in a matrix made of plasticized epoxy resin. Shrinkage stresses developed during the curing of the matrix around the already hardened inclusions. The elastic moduli of inclusions and matrix were chosen so that their ratio approximated to the ratio of the elastic moduli of aggregate and the hardened cement paste in concrete. Although this model is a simplified, plane configuration of the three-dimensional random arrangement of the aggregate in concrete, it depicts fairly accurately the state of stress around aggregate particles. Tensile stresses, developing at the interface between aggregate and cement paste, cause the development of micro crocks at the interface during the curing period of concrete and before any application of load. The effect of the ratio of the average diameter of aggregates to the average clear distance between them upon the stress distribution was also studied.
The problem of water absorption by lightweight aggregates
Authors: Lydon F. D.
Published: July 2012

Synopsis

It is desirable to be able to assess objectively the absorption of water by lightweight aggregates. Existing techniques do not lend themselves readily to this. A simple, objective test is described which uses the relationship between loose wet bulk density and moisture content of the test sample to determine graphically the moisture content corresponding to the surface-dry state. It is possible to test an aggregate sample after any (unknown) exposure history. Examples are given of Lytag, Aglite and Leca aggregates, for single sizes and graded samples, dry, mixed wet-and-dry and saturated and, despite complex behaviour exhibited by aggregates containing an appreciable amount of very fine material, the test method is seen to be successful.
Shear strength of prestressed concrete beams without web reinforcement
Authors: Kar J. N.
Published: July 2012

Synopsis

This paper presents the results of experimental and analytical studies on ultimate shear strength of prestressed concrete beams without web reinforcement and tested under either two-point or uniformly distributed loading. Factors governing the two principal categories of shear failure, namely shear-compression type and web-crushing type, have been examined. For shear-compression failure load, a semi-empirical characteristic equation has been developed from the analysis of test results on the basis of a modified linear strain diagram.
Creep and creep recovery of plain concrete as influenced by moisture conditions and associated variables
Authors: Meyers Bernard L. , Slate Floyd O.
Published: July 2012

Synopsis

Experiments designed to investigate the effects of moisture content, condition of the cement gel, time of loading and time of unloading upon the creep and creep recovery of sealed and unsealed concrete specimens are described. Comparisons are made between the creep and creep recovery responses of specimens sealed immediately after curing and of unsealed specimens. The results of the experiments carried out on the drying (unsealed) specimens were easily predictable by existing theory. However, the experiments performed on the sealed specimens produced data not so easily explained. For example, under certain conditions, the creep of unsealed specimens was less than that of sealed specimens, and a period of time during which the creep potential of sealed specimens increased with age at time of loading was observed. These results are discussed in terms of the major variables affecting the creep of concrete: the degree of hydration at the time of loading, the amount of water present and not chemically combined at the start of loading and while the specimen is under load, and the amount of m icro cracking developed in the system before and during the time under load.
Short-term time-dependent strains in hardened cement paste
Authors: Spooner D. C.
Published: July 2012

Synopsis

Measurements have been made of the strains which occur in cement paste specimens in the two minutes immediately after they have been loaded. At a given time after loading, the time-dependent component of the total strain has been found to be directly proportional to the applied stress, to increase with increasing temperature and to be substantially unaffected by the previous loading history. At a given time after loading andfor a given stress, both the elastic and the time-dependent strains are smaller, the older the specimen. The time-dependent component is largely recoverable on unloading, but less so for young specimens. It is suggested that the same processes govern this short-term time-dependent behaviour as govern longer-term creep. The elastic and time-dependent strains are thought to be caused by different processes.
The bearing strength of concrete for strip loadings
Authors: Hawkins N. M.
Published: July 2012

Synopsis

Results are reported for tests to failure on 39 concrete blocks loaded through rigid plates extending across the full width of the block. Expressions are developed for the ultimate bearing capacity andfor the length at which the crack on the axis of the load propagates spontaneously. These expressions predict correctly the ultimate strengths measured here and in previous investigations. It is shown that the pattern of cracking remote from the loaded area affects the ultimate strengths significantly, and that the general behaviour is not improved by the provision of a cut-out.
Some results for the average stresses induced in the principal components of concrete
Authors: Dougill J. W.
Published: July 2012

Synopsis

Results are obtained for the average stresses in the separate phases of a range of conventional concretes. These results show that the larger particles of aggregate are more highly stressed than the smaller material in the concrete mix and also confirm that, for a concrete in uniaxial compression, the cement paste or mortar is in a state of average triaxial compression during the early stages of loading. It is suggested that the sign of the average stress in the separate phases may be used as an indicator of the mode of failure likely to occur in a concrete under any particular stress combination. Results for conventional concretes support this view and it is considered that the indicator will also be useful in studying the behaviour of high-strength and of lightweight-aggregate concretes.
The behaviour of prestressed concrete frames with and without lateral binders under ultimate load
Authors: Chatterji A. K.
Published: July 2012

Synopsis

The paper describes briefly the results of tests on three prestressed concrete portal frames with fixed feet. The first two frames were identical except that one had closely spaced binders at critical sections whilst the other had no binders. The third frame had heavy axial loads; it was similar to Pietrzykowski's frame, but was reinforced with closely spaced binders throughout the length of its members. The author concludes from the test results that checking of rotations cannot be dispensed with, at least in cases of over-reinforced I sections in prestressed members, for which Baker's predictions are on the unsafe side. However, adequate rotations to enable a frame to attain a state of full redistribution of moments may be obtained, irrespective of the fact that the critical sections may be over-reinforced or may be subjected to high axial loads, provided the frame is reinforced with an adequate amount of binders.
Application of mathematical programming to yield-line analysis
Authors: Palmer Andrew C.
Published: July 2012

Synopsis

A computer technique is proposed as a means of solving the problem of finding the yield-line pattern which minimizes the collapse load on a slab. A mechanism is assumed and the collapse load calculated as a function of several pattern parameters. A previously constructed sub-routine is then used to minimize this function and thus find the most critical mechanism. Two examples are given; the computation time required is extremely small.
Some shear strength parameters of plastic concrete
Authors: Uzomaka Osondu J.
Published: July 2012

Synopsis

The shear strength parameters of plastic concrete were studied with particular reference to the effect of water/cement ratio. ‘Unconsolidated-undrained’ and ‘consolidated-undrained’ triaxial tests were performed, pore-water pressures were measured, and shear strength parameters have been determined in terms of both total and effective stresses. The shear strength parameters of the material, when tested in the unconsolidated-undrained state, decreased linearly with increase in water/cement ratio. On the other hand, the parameters appear to be independent of water/cement ratio when the material is tested in the consolidated-undrained condition, except for the maximum induced pore pressure, which varies directly with both the water/cement ratio and the ambient pressure. The second result suggests the existence of a close relationship between the initial water/cement ratio and the amount of mobile water that can be expelled from the mix at any given ambient pressure.
The apparatus and instrumentation for an investigation of the strains in mass concrete due to fluid pore pressure
Authors: Cullington D. W. , Mayfield B.
Published: July 2012

Synopsis

The paper describes the apparatus and instrumentation that is being used to investigate the effects of triaxial stresses, including pore pressure, upon mass concrete. The specimens are hollow cylinders approximately 1·5 m high × 0·7 m outside diameter × 0·23 m inside diameter, of concrete with a 19 mm maximum aggregate size and a 28 day cube strength of approximately 28 to 42 N/mm2
A method for ultimate strength design of rectangular reinforced concrete beams in combined torsion, bending and shear
Authors: Kuyt B.
Published: July 2012

Synopsis

An analysis of the distribution offorces in rectangular reinforced concrete beams loaded in pure torsion has been given elsewhere. In this paper the analysis is extended to beams with web reinforcement subjected to combined torsion, shear and bending. A comparison is made between the non-dimensional interaction diagrams derived theoretically and the available results of tests. Finally, a proposal is put forward for design equations based on these diagrams.
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.