bluuebunny/crossref_metadata_2025 huggingface dataset:
Atypical vitelliform macular dystrophy misdiagnosed as chronic central serous chorioretinopathy: case reports
Authors: Lee Young Seob , Kim Eung-Suk , Kim Moosang , Kim Young-Gyun , Kwak Hyung-Woo , Yu Seung-Young
Published: July 2012

Background

To report two cases of atypical vitelliform macular dystrophy misdiagnosed as chronic central serous chorioretinopathy.

Case presentation

Two patients with incidentally discovered abnormalities of the retina without specific symptoms were referred to our hospital for consultation. Bilateral macula atrophic lesions were observed and optical coherence tomography revealed serous retinal detachment in the macula. Fluorescein angiography showed multiple leakages around the central hypofluorescent area and indocyanine green angiography showed partially dilated choroidal vessels. Fundus autofluorescence (FAF) showed a decreasing pattern of autofluorescence in the subretinal fluid area, and increasing autofluorescence at the border of the serous retinal detachment. Both patients were diagnosed with chronic central serous chorioretinopathy. Photodynamic therapy and intravitreal bevacizumab injection were administered for engorged choroidal vessels during follow-up, but neither patient showed improvement in symptoms or ophthalmologic findings. Based on re-evaluation by fundus photography, optical coherence tomography, fluorescein angiography, and comparison of the results of FAF with the first visit, vitelliform macular dystrophy was suspected and a definite diagnosis was made by electrooculography and genetic testing.

Conclusion

In patients with continuous serous retinal detachment without response to photodynamic therapy or intravitreal bevacizumab injection, careful fundus exam and FAF can be used to diagnose atypical vitelliform macular dystrophy.
Ocular toxicity of authentic lunar dust
Authors: Meyers Valerie E , Garcìa Hector D , Monds Kathryn , Cooper Bonnie L , James John T
Published: July 2012

Background

Dust exposure is a well-known occupational hazard for terrestrial workers and astronauts alike and will continue to be a concern as humankind pursues exploration and habitation of objects beyond Earth. Humankind’s limited exploration experience with the Apollo Program indicates that exposure to dust will be unavoidable. Therefore, NASA must assess potential toxicity and recommend appropriate mitigation measures to ensure that explorers are adequately protected. Visual acuity is critical during exploration activities and operations aboard spacecraft. Therefore, the present research was performed to ascertain the ocular toxicity of authentic lunar dust.

Methods

Small (mean particle diameter = 2.9 ± 1.0 μm), reactive lunar dust particles were produced by grinding bulk dust under ultrapure nitrogen conditions. Chemical reactivity and cytotoxicity testing were performed using the commercially available EpiOcularTM assay. Subsequent in vivo Draize testing utilized a larger size fraction of unground lunar dust that is more relevant to ocular exposures (particles <120 μm; median particle diameter = 50.9 ± 19.8 μm).

Results

In vitro testing indicated minimal irritancy potential based on the time required to reduce cell viability by 50% (ET50). Follow-up testing using the Draize standard protocol confirmed that the lunar dust was minimally irritating. Minor irritation of the upper eyelids was noted at the 1-hour observation point, but these effects resolved within 24 hours. In addition, no corneal scratching was observed using fluorescein stain.

Conclusions

Low-titanium mare lunar dust is minimally irritating to the eyes and is considered a nuisance dust for ocular exposure. No special precautions are recommended to protect against ocular exposures, but fully shielded goggles may be used if dust becomes a nuisance.
Wound healing activities of different extracts of Centella asiatica in incision and burn wound models: an experimental animal study
Authors: Somboonwong Juraiporn , Kankaisre Mattana , Tantisira Boonyong , Tantisira Mayuree H
Published: July 2012

Background

The efficacy ofCentella asiaticafor incision and burn wounds are not fully understood. Here, we report the wound healing activities of sequential hexane, ethyl acetate, methanol, and water extracts ofCentella asiaticain incision and partial-thickness burn wound models in rats.

Methods

Male Sprague–Dawley rats weighing 250–300 g were randomly divided into incision and burn wound groups. Each group was stratified into seven subgroups: (1) untreated; (2) NSS-; (3) Tween 20®- (vehicle control); (4) hexane extract-; (5) ethyl acetate extract-; (6) methanol extract-; and (7) aqueous extract-treated groups. The test substances were applied topically once daily. The tensile strength of the incision wound was measured on the seventh day after wound infliction. The general appearance and degree of wound healing of the burn wound were assessed on Days 3, 7, 10 and 14 after burn injury and prior to histopathological evaluation.

Results

On the seventh day after wound infliction, the tensile strength of incision wound in all extract-treated groups was significantly higher than that of the vehicle control (Tween 20®), but comparable to the NSS-treated group. The degrees of healing in the burn wound with the four extracts were significantly higher than that of the control on Days 3, 10 and 14. Histopathological findings on Day 14 after burn injury revealed prominent fibrinoid necrosis and incomplete epithelialization in the control and untreated groups, whereas fully developed epithelialization and keratinization were observed in all extract-treated groups. Analysis by thin layer chromatography demonstrated that the phyto-constituents β-sitosterol, asiatic acid, and asiaticoside and madecassocide were present in the hexane, ethyl acetate and methanol extracts, respectively.

Conclusions

All extracts ofCentella asiaticafacilitate the wound healing process in both incision and burn wounds. Asiatic acid in the ethyl acetate extract seemed to be the most active component for healing the wound.
Ethnic differences in the use of intrapartum epidural analgesia
Authors: Jiménez-Puente Alberto , Benítez-Parejo Nicolás , Del Diego-Salas Jorge , Rivas-Ruiz Francisco , Maañón-Di Leo Claudio
Published: July 2012

Background

Obstetric epidural analgesia (EA) is widely applied, but studies have reported that its use may be less extensive among immigrant women or those from minority ethnic groups. Our aim was to examine whether this was the case in our geographic area, which contains an important immigrant population, and if so, to describe the different components of this phenomenon.

Methods

Cross-sectional observational study. Setting: general acute care hospital, located in Marbella, southern Spain. Analysis of computer records of deliveries performed from 2004 to 2010. Comparison of characteristics of deliveries according to the mothers’ geographic origins and of vaginal deliveries noting whether EA was received, using univariate and bivariate statistical analysis and multiple logistic regression (MLR).

Results

A total of 21,034 deliveries were recorded, and 37.4% of these corresponded to immigrant women. EA was provided to 61.1% of the Spanish women and to 51.5% of the immigrants, with important variations according to geographic origin: over 52% of women from other European countries and South America received EA, compared with around 45% of the African women and 37% of the Asian women. These differences persisted in the MLR model after adjusting for the mother's age, type of labor initiation, the weight of the neonate and for single or multiple gestation. With the Spanish patients as the reference category, all the other countries of origin presented lower probabilities of EA use. This was particularly apparent for the patients from Asia (OR 0.38; 95%CI 0.31-0.46), Morocco (OR 0.49; 95%CI 0.43-0.54) and other Africa (OR 0.55; 95%CI 0.37-0.81).

Conclusions

We observed a different use of EA in vaginal deliveries, according to the geographic origin of the women. The explanation for this involves a complex set of factors, depending both on the patient and on the healthcare staff.
Therapeutic efficacy and safety of dihydroartemisinin-piperaquine versus artesunate-mefloquine in uncomplicated Plasmodium falciparum malaria in India
Authors: Gargano Nicola , Ubben David , Tommasini Silva , Bacchieri Antonella , Corsi Marco , Bhattacharyya Prabhash C , Rao Bappanad HK , Dubashi Nagesh , Dev Vas , Ghosh Susanta K , Kumar Ashwani , Srivastava Bina , Valecha Neena
Published: July 2012

Background

Resistance in Plasmodium falciparum to commonly used anti-malarial drugs, especially chloroquine, is being increasingly documented in India. By 2007, the first-line treatment for uncomplicated malaria has been revised to recommend artemisinin-based combination therapy (ACT) for all confirmed P. falciparum cases.

Objective

The objective of this study was to compare the efficacy, safety and tolerability between dihydroartemisinin-piperaquine (DP) and artesunate plus mefloquine (A + M) drug combinations in the treatment of uncomplicated P. falciparum malaria in India.

Methods

Between 2006 and 2007, 150 patients with acute uncomplicated P. falciparum malaria were enrolled, randomized to DP (101) or A + M (49) and followed up for 63 days as part of an open-label, non-inferiority, randomized, phase III multicenter trial in Asia.

Results

The heterogeneity analysis showed no statistically significant difference between India and the other countries involved in the phase III study, for both the PCR-corrected and uncorrected cure rates. As shown at the whole study level, both forms of ACT were highly efficacious in India. In fact, in the per protocol population, the 63-day cure rates were 100% for A + M and 98.8% for DP. The DP combination exerted a significant post-treatment prophylactic effect, and compared with A + M a significant reduction in the incidence of new infections for DP was observed (respectively 17.1% versus 7.5% of patients experienced new infection within follow up). Parasite and fever clearance was rapid in both treatment arms (median time to parasite clearance of one day for both groups). Both DP and A + M were well tolerated, with the majority of adverse events of mild or moderate severity. The frequencies of individual adverse events were generally similar between treatments, although the incidence of post treatment adverse events was slightly higher in patients who received A + M with respect to those treated with DP.

Conclusion

DP is a new ACT displaying high efficacy and safety in the treatment of uncomplicated P. falciparum malaria and could potentially be considered for the first-line treatment of uncomplicated falciparum malaria in India.

Trial registration

Current Controlled Trials ISRCTN 81306618
Strong convergence theorems for solving a general system of finite variational inequalities for finite accretive operators and fixed points of nonexpansive semigroups with weak contraction mappings
Authors: Onjai-uea Nawitcha , Katchang Phayap , Kumam Poom
Published: July 2012

In this paper, we prove a strong convergence theorem for finding a common solution of a general system of finite variational inequalities for finite different inverse-strongly accretive operators and solutions of fixed point problems for a nonexpansive semigroup in a Banach space based on a viscosity approximation method by using weak contraction mappings. Moreover, we can apply the above results to find the solutions of the class of k-strictly pseudocontractive mappings and apply a general system of finite variational inequalities into a Hilbert space. The results presented in this paper extend and improve the corresponding results of Ceng et al. (2008), Katchang and Kumam (2011), Wangkeeree and Preechasilp (2012), Yao et al. (2010) and many other authors.

MSC:47H05, 47H10, 47J25.
Fixed point theorems for left amenable semigroups of non-Lipschitzian mappings in Banach spaces
Authors: Huang Qianglian , Zhu Lanping , Li Gang
Published: July 2012

In this paper, we provide the existence and convergence theorems of fixed points for left amenable semigroups of asymptotically nonexpansive type mappings in general Banach spaces, which extend and improve many recent results in this area.

MSC:47H09, 47H10, 47H20.
Characterization and compilation of polymorphic simple sequence repeat (SSR) markers of peanut from public database
Authors: Zhao Yongli , Prakash Channapatna S , He Guohao
Published: July 2012

Background

There are several reports describing thousands of SSR markers in the peanut (Arachis hypogaea L.) genome. There is a need to integrate various research reports of peanut DNA polymorphism into a single platform. Further, because of lack of uniformity in the labeling of these markers across the publications, there is some confusion on the identities of many markers. We describe below an effort to develop a central comprehensive database of polymorphic SSR markers in peanut.

Findings

We compiled 1,343 SSR markers as detecting polymorphism (14.5%) within a total of 9,274 markers. Amongst all polymorphic SSRs examined, we found that AG motif (36.5%) was the most abundant followed by AAG (12.1%), AAT (10.9%), and AT (10.3%).The mean length of SSR repeats in dinucleotide SSRs was significantly longer than that in trinucleotide SSRs. Dinucleotide SSRs showed higher polymorphism frequency for genomic SSRs when compared to trinucleotide SSRs, while for EST-SSRs, the frequency of polymorphic SSRs was higher in trinucleotide SSRs than in dinucleotide SSRs. The correlation of the length of SSR and the frequency of polymorphism revealed that the frequency of polymorphism was decreased as motif repeat number increased.

Conclusions

The assembled polymorphic SSRs would enhance the density of the existing genetic maps of peanut, which could also be a useful source of DNA markers suitable for high-throughput QTL mapping and marker-assisted selection in peanut improvement and thus would be of value to breeders.
Extending and encoding existing biological terminologies and datasets for use in the reasoned semantic web
Authors: Samadian Soroush , McManus Bruce , Wilkinson Mark D
Published: July 2012

Background

Clinical phenotypes and disease-risk stratification are most often determined through the direct observations of clinicians in conjunction with published standards and guidelines, where the clinical expert is the final arbiter of the patient’s classification. While this "human" approach is highly desirable in the context of personalized and optimal patient care, it is problematic in a healthcare research setting because the basis for the patient's classification is not transparent, and likely not reproducible from one clinical expert to another. This sits in opposition to the rigor required to execute, for example, Genome-wide association analyses and other high-throughput studies where a large number of variables are being compared to a complex disease phenotype. Most clinical classification systems and are not structured for automated classification, and similarly, clinical data is generally not represented in a form that lends itself to automated integration and interpretation. Here we apply Semantic Web technologies to the problem of automated, transparent interpretation of clinical data for use in high-throughput research environments, and explore migration-paths for existing data and legacy semantic standards.

Results

Using a dataset from a cardiovascular cohort collected two decades ago, we present a migration path - both for the terminologies/classification systems and the data - that enables rich automated clinical classification using well-established standards. This is achieved by establishing a simple and flexible core data model, which is combined with a layered ontological framework utilizing both logical reasoning and analytical algorithms to iteratively "lift" clinical data through increasingly complex layers of interpretation and classification. We compare our automated analysis to that of the clinical expert, and discrepancies are used to refine the ontological models, finally arriving at ontologies that mirror the expert opinion of the individual clinical researcher. Other discrepancies, however, could not be as easily modeled, and we evaluate what information we are lacking that would allow these discrepancies to be resolved in an automated manner.

Conclusions

We demonstrate that the combination of semantically-explicit data, logically rigorous models of clinical guidelines, and publicly-accessible Semantic Web Services, can be used to execute automated, rigorous and reproducible clinical classifications with an accuracy approaching that of an expert. Discrepancies between the manual and automatic approaches reveal, as expected, that clinicians do not always rigorously follow established guidelines for classification; however, we demonstrate that "personalized" ontologies may represent a re-usable and transparent approach to modeling individual clinical expertise, leading to more reproducible science.
Clinical significance of E2F1 protein expression in non-small cell lung cancer
Authors: Hung Jung-Jyh , Hsueh Chung-Tsen , Chen Kuan-Hua , Hsu Wen-Hu , Wu Yu-Chung
Published: July 2012

Background

The transcription factor E2F1 has been implicated in cell cycle control and DNA damage response. Paradoxically, E2F1 can promote apoptosis and function as tumor suppressor. In non-small cell lung cancer (NSCLC), there are conflicting data for clinical significance of E2F1 expression. In this study, we investigated the protein expression of E2F1 in patients with stage I-III NSCLC, and its correlation with clinical outcome.

Results

56 paired adjacent non-tumor/tumor matched samples were prospectively obtained from patients undergoing surgery for stage I-III NSCLC at Taipei Veterans General Hospital. The protein expression of E2F1 was determined by Western blot analysis. The levels of E2F1 protein were significantly higher in tumor samples than in non-tumor lung specimens (P = 0.008). Overexpression of E2F1 was defined as a more than 2-fold expression in the tumorous sample compared with the corresponding nontumorous one, and was noted in 21 patients (37.5%). There was no significant difference in overall survival (P = 0.44) or probability of freedom from recurrence (P = 0.378) between patients with E2F1 overexpression vs. non-overexpressors. Additionally, there was no significant association between E2F1 overexpression and any clinicopathologic parameter such as histological type, stage, or angiolymphatic invasion of tumor.

Conclusion

E2F1 protein is frequently overexpressed in NSCLC. There is no correlation between E2F1 protein expression and clinical outcome such as survival and freedom from progression.
Involvement in research without compromising research quality
Authors: Stewart Ruth , Liabo Kristin
Published: July 2012

Health research funders in the UK now ask applicants to state how their research will involve patients and members of the public. Such involvement can help with questions that researchers repeatedly face: about improving trial recruitment, response rates and follow-up. Patient and Public Involvement (PPI) in research is usually presented in the form of a ladder, from a low rung where studies are led by researchers with no patient involvement, to a high rung where studies are patient-led. This hierarchy does not sit well with many clinicians and academics whose expertise appears to have been downgraded. This article argues that research quality and relevance are optimised when patient expertise is integrated with researchers’ and policy-makers’ expertise, and each role acknowledged and valued, illustrated by an alternative model for PPI which places research and expertise at the centre of the involvement enterprise.
Adsorption of gold(III) on ionic imprinted amino-silica hybrid prepared from rice hull ash
Authors: Sakti Satya Candra Wibawa , Siswanta Dwi , Nuryono
Published: July 2012

In this research, the adsorption of Au(III) ion on ionic imprinted amino-silica hybrid (Im-ASH) in aqueous solution has been studied. Im-ASH was synthesized via sol-gel technique using a solution of sodium silicate (Na2SiO3) from rice hull ash (RHA) as the precursor and Au(III) ion as the template. Adsorption was carried out in a batch system with variation of pH, contact time, and Au(III) ion concentration. The selectivity of adsorbent toward Au(III) was examined in the presence of Cu(II) ion. The result of the kinetic study demonstrated that the adsorption of Au(III) ion followed pseudo-second order. The optimum adsorption of Au(III) on Im-ASH and non-Im-ASH was obtained at pH of 3.0. Im-ASH was twice as selective toward Au(III) ion than ASH was.
Some experiments on the load distribution in bond tests
Authors: Wilkins R. J.
Published: July 2012

Summary:

Tests are briefly described in which the bond stress distribution has been obtained for tubes embedded in concrete and used as “pull-out” specimens. Electrical resistance strain gauges were inserted in straight lengthy of steel tubing to form the measuring devices which can be used for direct calibratiqn against load. These tubes were then embedded along the axis of cylinders of concrete to form “pull-out” specimens of the usual type. Readings of the strain gauges taken as the tube was being withdrawn from the concrete enabled the load distribution curves to be plotted. The variation of bond stress has been studied from the information provided by the load distribution curves, and values are given for average and maximum bond stress for various embedded lengths and types of tube surface. The results obtained from an American bar of “Hi-bond” type with a patterned surface are included.

The experimental method has proved to be satisfactory in use and capable of providing sufficient data for plotting load distribution curves of reasonable accuracy. The transition of the load from the end at which it is applied to the free end of the tube has been observed, and the method enables the mechanism of bond failure to be investigated. The most important influence appears to be the character of the contact surface, and it is considered that the tests indicate that bond may be caused by (a) adhesion, (b) friction, and (c) mechanical wedging. The relative importance of these factors is apparently controlled by the type of surface, but further work on this subject is in progress.
On the combined use of pre-tensioning and post-tensioning methods
Authors: Lazarides T. O.
Published: July 2012

Summary:

The combined use ol pre-tensioning and post-tensioning methods makes it possible to superimpose two systems of stresses in certain parts of a structure while other parts are stressed by one system only; the advantages of using pre-tensioning for the one component are that it introduces no anchors in the interior of the structure and facilitates the handling of component parts.
Measurement of the work done in compacting a known weight of concrete by vibration
Authors: Venkatramaiah Salagame
Published: July 2012

Summary:

An attempt has been made to measure the work done in compacting a known weight of concrete using an electrical vibrator. Tests have been carried out so that estimates of the electrical anti frictional losses could be made, thereby enabling the net work done in compacting the concrete to be calculated. The results obtained by this method have been compared with the results of compacting factor tests made on the same concretes.
Ultimate strength theory for eccentrically loaded reinforced concrete columns
Authors: Cowan Henry J.
Published: July 2012

Summary

This paper presents a method for computing the ultimate strength of reinforced concrete sections subject to combined bending and compression. It is based on the idealized stress-strain diagram proposed by Emperger and developed by Jensen, in which the compressive strain of the concrete at failure is divided into a perfectly elastic and a perfectly plastic stage. Equations for the ultimate column load are derived (i) for primary tension failure of the steel and (ii) for primary compression failure of the concrete.
The encasement of rolled steel joists in concrete
Authors: Jones G. A.
Published: July 2012

Summary:

The existing allowances Jor concrete encasement of steel joists are shown to be not as comprehensive as they might be. The testing of specimens which have been chosen to give as wide a picture as possible of the general behaviour of the unit is described, together with the results, observations, and conclusions derived therefrom.

Attention is paid to relations between the maximum steel and concrete stresses, deflexions, increases in strength, bond between the members and the stability of the compression flange.

An elastic theory as adapted for the augmented steel is recorded.
Ultimate strength theory for short reinforced concrete cylindrical shell roofs
Authors: Baker A. L. L.
Published: July 2012

Summary

The theory proposed by Professor Baker in Magazine of Concrete Research No.4, in which he provides a simple method for designing shell roofs including prestressed shells, is extended to include shells in which longitudinal slab bending is not negligible.
On centres of twist in non homogeneous beams
Authors: Morice P. B.
Published: July 2012

Summary

A theory is presented for the determination of the position of the centre of twist in an ideal unsymmetrically reinforced beam having a constant narrow rectangular cross-section. The basis of the theory is the shortening effect in longitudinal fibres produced by twist.
The effect of the method of test on the flexural strength of concrete
Authors: Wright P. J. F. , Garwood F.
Published: July 2012

Summary

As a basis for standardizing a method of test for the modulus of rupture of concrete, flexure tests have been carried out on beams of various sizes using central and third-point methods of loading and various rates of loading. Tests were also carried out on small beams sawn from larger ones in order to isolate the effects of specimen size.

A reduction of approximately 30 per cent was observed in the modulus of rupture when the depth of the beam was increased from 3 in. to 8 in. for a span-depth ratio of 3, but other effects of size were small. Increasing the rate of increase of stress from 20 to 1,140 lb per sq.in. per min. resulted in an increase of about IS per cent in the modulus of rupture. Centnil loading gave results about 20 to 25 per cent higher than third-point loading but the results were less uniform.

The effects of the size of specimen have largely been accounted for by variations in the quality of the concrete in beams of different sizes together with a statistical aspect termed the “weakest link” theory, and an effect due to changes in the rate of increase of stress. The effect of the method of loading can largely be explained by the “weakest link” theory and by considerations of the stress distributions in the comparatively short beams used.

As a result of the investigation it should now be possible to relate the results from the standard procedure now adopted at the Road Research Laboratory to those from other laboratories using different procedures.
Factors governing the ultimate bending moment of normal reinforced and prestressed concrete beams, with reference to a proposed plastic theory
Authors: Revesz Stephen
Published: July 2012

Summary

The different modes of failure of concrete beams are examined and classified. An analytical treatment is proposed in which the shape of the compression stress diagram for a given concrete strength varies with the ultimate bending moment for the particular section. The proposed ultimate load theory is compared with the results of 84 beam tests of the following types: (a) normally reinforced, (b) pre-tensioned, (c) post-tensioned unbollded, and (d) post-tensioned and grouted.

Recommendation is made for the adoption of a “limiting” ultimate bending moment for a beam section of given dimensions and a particular concrete strength. Reasolls are discussed which necessitate the use of the above “limiting” value.
The Scientific Research Department of “S.A. Cimenteries et Briqueteries Réunies”, Brussels
Authors: Janssens P. F.
Published: July 2012

Summary

The paper describes the Research Department of the Belgian company “S.A. Cimenteries et Briqueteries Réunies” which was set up at Brussels in 1950.

An outline of the aims and organization of the Department is given, in which it will be noted that particular stress is laid on the Documentation Service—the vital link between research workers the world over.

The paper then goes on to describe the type of research the organization is presently engaged on, and includes details of the apparatus at the disposal of the research staff.
New equipment in the Reinforced Concrete Laboratory at the University of Ghent for static and dynamic testing of large structural members
Authors: Riessauw F. G.
Published: July 2012

Summary

The author draws attention to the importance of dynamic tests, particularly on large specimens. Details are given of the equipment recently installed in Professor Magnel's laboratory which enables such tests to be made, and the paper includes a description of the prestressed concrete foundation slab, 1·3 m. thick, which was required.

The main characteristics of the pulsators are described, and examples are given of the many applications of the equipment.
The structural design of concrete roads
Authors: Sparkes F. N.
Published: July 2012

Summary

This paper reviews present knowledge of the thickness, length and width of concrete road slabs, the use of reinforcement and the functions and design of joints. Consideration is given to the factors causing stresses; while approximate estimates may be made of the stresses caused by wheel loads, temperature gradients and changes in the mean temperature of the slab, it is not possible to calculate the stresses caused by certain other factors. It is therefore necessary to rely on the knowledge gained from experience and experiment when making recommendations. for future designs.

The thicknesses recommended for five different traffic conditions and for three soil divisions are given in Table 1. It is considered that the strength properties of the soil are of less importance than the uniform behaviour of the soil and the avoidance of differential deformations. It is contended that the base only serves a useful purpose on poor soils and to resist the effects of frost.

The spacing recommended for joints is a compromise between the desire to reduce the number of joints as much as possible and the need for providing some facility for the slabs to expand and contract. The recommended spacings are given in Table 2.

It is now accepted that reinforcement is necessary if the effect of cracking is to be minimized or eliminated. Consideration is given to the position and the amount of the reinforcement, and the recommended quantities for different soil and traffic conditions are enumerated in Table 3.

The functions of the various types of transverse joint used in concrete road construction are discussed and details are given in Figures 4—8 of suitable designs for transverse and longitudinal joints.
Compaction and flow of concrete
Authors: Poucher M. P.
Published: July 2012

Summary

Tests are briefly described for a comparison between the workability and mobility of concrete mixes suitable for compaction by vibration. Variations in the mix design for high-quality concretes are discussed, stress being placed on the concrete containing a high proportion of the maximum sized aggregate.
A study of the tensile strength of concrete across construction joints
Authors: Waters T.
Published: July 2012

Summary

In this report are discussed the relative merits of various types of treatment to an existing concrete surface before fresh concrete is placed against it to form a construction joint. Results of tests of the tensile strength of joints made in various ways are given, and they show that, contrary to modern practice, old concrete should be left dry when the new concrete is placed against it. They also show that surfaces cleaned by abrasive methods such as wire brushing and sandblasting, are slightly superior to scabbled surfaces.

The results of a second series of tests are given which show that the age of the hardened concrete at the time of placing the new has little effect on the strength of the joint.
Effect of capping on the compressive strength of concrete cubes
Authors: Ahmed S.
Published: July 2012

Summary

This paper describes the effect of various methods of capping on the compressive strength of concrete. It was found that capping the concrete faces with a molten mixture of sulphur, sand and carbon black gives the least scatter of test results and strength values which appear most representative. With some capping materials, however, a reduction of about 10 to 50 per cent in strength was obtained.
A load distribution theory for bridge slabs allowing for the effect of Poisson's ratio
Authors: Rowe R. E.
Published: July 2012

Summary

A load distribution theory for bridge slabs in which account is taken of the effect of Poisson's ratio is presented. The effect of the value of Poisson's ratio on the theoretical distribution factors for de flexions and longitudinal bending moments is discussed. In the case of the transverse bending moments a series of curves for the distribution coefficient, μ, have been prepared from which accurate assessments of the moments can be made allowing for a Poisson's ratio of 0·15, i.e. for materials such as reinforced and prestressed concrete.
Load distribution in multi-webbed bridge structures from tests on plastic models
Authors: Little G. , Rowe R. E.
Published: July 2012

Summary

A multi-webbed bridge structure is one which is intermediate between the two extreme cases, i.e. a no-torsion grillage and a full-torsion slab, considered in the load distribution analyses.

The theoretical interpolation formula which gives the distribution factors for this type of construction makes use of a torsion parameter, α. Tests have been made on Perspex bridge models to determine the correct value of this parameter to be consistent with the assumptions of analysis.
A method of measuring the surface texture of aggregate
Authors: Wright P. J. F.
Published: July 2012

Summary

A method has been developed for measuring quantitatively the surface texture of particles of concrete aggregate. Various possibilities were considered; the method adopted involves embedding a particle of aggregate in a synthetic resin and obtaining thin sections of the aggregate surrounded by the resin. The interface between stone and resin is magnified 125 times on a projection microscope and traced. The length of the profile obtained is measured by means of a map-measuring wheel and compared with the length of an unevenness line drawn as a series of chords. The difference between the two lengths is taken as a measure of the roughness.

The reproducibility of the results is good but the variation between different parts of a stone is large. Thus it is necessary to obtain a considerable number of results in order to give a reliable average. This is largely because of the smallness of the sample length: one tenth of an inch. The method has been used to compare the roughness of a series of twelve different aggregates.

It has long been recognized that the surface texture of a particle of aggregate might be an important property in determining the adhesion of binders to its surface. The degree of adhesion might, in turn, be expected to influence the properties of the mix.

Difficulty has been encountered in assessing the surface texture quantitatively, and although several methods have been developed to some degree, none has so far been generally accepted or widely used. The method described in this article was developed at the Road Research Laboratory as part of an investigation into the effect of the physical characteristics of aggregates on the properties of concrete made with them.
The measurement of the workability of dry concrete mixes
Authors: Cusens A. R.
Published: July 2012

Summary

The paper describes tests on a number of dry mixes, using the Vebe and compacting factor principles, together with a third test based on the compacting factor test. The modified compacting factor test substitutes a period of vibration for the fall under gravity of the normal apparatus.

It is shown that the normal compacting factor test does not reflect the compaction properties of very dry mixes, as the amount of work done on the concrete is too small. The Vebe test is shown to be satisfactory and is recommendedfor more general use with dry mixes.
Determination of the heat of hydration of cements containing slag or pozzolana
Authors: Nurse R. W. , Pai V. N.
Published: July 2012

Summary

In determining the heat of hydration from the heats of dissolution in an acid mixture according to the method described in B.S. 1370:1947, an insoluble residue remains if the original cement contained slag, anhydrite or pozzolana. It is shown that the heat of hydration can nevertheless be determined with good accuracy provided the heat loss from the calorimeter is determined in a separate experiment.
Some observations on calcium silicate hydrate (I)—tobermorite
Authors: Gaze R. , Robertson Robert H. S.
Published: July 2012

Summary

Electron-optical study of commercial products containing calcium silicate hydrate has revealed the presence of tobermorite in the form of plates or thin foils. This has apparently been possible as a result of the relatively crumbly nature of the products, enabling samples to be mounted without damage to the fragile crystals. Differential thermal analyses of the materials did not reveal the presence of more than a trace of calcite, although carbon dioxide was present in appreciable quantities.
A constant temperature and humidity curing cabinet
Authors: Hughes B. P.
Published: July 2012

Summary

This paper describes a concrete curing cabinet which was constructed in the Civil Engineering Department of the University of Birmingham, preparatory to a programme of research into concrete mix design. The apparatus, efficient and reliable in service, has been added to the concrete laboratory at comparatively small cost. The design can be used to advantage wherever accurate temperature control of the entire laboratory is impossible.
An appreciation of the work carried out on fatigue in prestressed concrete structures
Authors: Rowe R. E.
Published: July 2012

Summary

A review of the work carried out on fatigue in prestressed concrete is made in this report and observations by the various investigators are included.

All the tests show the excellent fatigue resistance of prestressed concrete in the design range of loading. From the review it is apparent that for loadings outside the design range, i.e. after cracking has occurred, the governing factor affecting the fatigue strength of prestressed concrete is the fatigue strength of the high-tensile steel used for stressing. Figures obtained for the fatigue strength of high-tensile wires show that for most types in present use a mean value of 60–65% of the ultimate strength should be taken. No comparable figures for the fatigue strength of high-tensile alloy bars are available.

Suggestions are put forward for future research on fatigue in prestressed concrete and the need is emphasized for fundamental research into the behaviour of both high-tensile wires and high-tensile alloy steel bars under fatigue conditions.
The effect of frequency on the dynamic modulus and damping coefficient of concrete
Authors: Jones R.
Published: July 2012

Summary

Experiments have been made to determine the resonant frequencies of concrete beams in flexural, longitudinal, and torsional modes of vibration at the fundamental and higher harmonics. The results were used to study the effect of frequency on the dynamic Young's modulus and dynamic shear modulus.

It was found that for wet concrete there was no appreciable difference in the dynamic Young's modulus determinedfrom the flexural and longitudinal modes of vibration. The modulus changed by less than 3% as the frequency increasedfrom 70 to 10,000 c/s. The dynamic shear modulus also showed no appreciable change with frequency over the range of 700-10,000 c/s.

When the concrete beam was allowed to dry, the Young's modulus calculated from the flexural vibrations was lower than that calculated from longitudinal vibrations. The discrepancy is attributed to moisture differences within the concrete beam. It is suggested that surface drying of concrete beams might account for the differences of modulus previously observed in flexure between beams of different size made of nominally the same concrete.

The damping coefficient in the moist concrete did not change appreciably withfrequency and, at a particular age, was approximately the same for all three modes of vibration. It is concluded that damping of the vibrations arises chiefly at the interfacial boundaries within the concrete.
The resistance of concrete pumped through pipelines
Authors: Ede A. N.
Published: July 2012

Summary

The lack of adequate data made necessary the investigation of the basic mechanics of concrete pumping. Unsaturated materials pass stresses by inter-particle contact and give rise on commencement of movement to a pressure build-up which in a non-tapering duct is exponential with distance pumped. Adequate saturation by water/cement paste reduces the resistance to a favourable linear type, subject to increase with velocity, but independent of operating pressure.
The effect of compressive stress on the dynamic modulus of concrete
Authors: Elvery R. H. , Furst M.
Published: July 2012

Summary

Tests have been carried out to determine the effect of compressive stress on the dynamic modulus of concrete. These have indicated that a small reduction of modulus occurs when concrete is loaded but that no subsequent reductions occur while the load is maintained for periods up to six months. A similar reduction also occurs on releasing the load and with subsequent loading cycles. This effect, which is independent of the age of the concrete after fourteen days, is approximately proportional to the applied stress and becomes successively smaller for subsequent loading cycles. The reduction in dynamic modulus is always small, being about 5% or less.
The influence of shear span and concrete strength upon the shear resistance of a pre-tensioned prestressed concrete beam
Authors: Hicks A. B.
Published: July 2012

Summary

The research was planned to establish the various types of failure of a typical pre-tensioned prestressed concrete I beam, to establish the limits of the shear span to depth ratio within which each type of failure occurred, and, generally, to investigate the effect of the shear span and concrete strength upon the shear resistance of a concrete beam of this type.

Four types offailure were observed; a fifth (bond failure) was carefully avoided. The limits of the shear span to depth ratio within which each type of failure occurred were as follows: shear distortion 0-1½ diagonal compression 1½-4½ to 5 diagonal tension 4½ to 5-9 flexural 9-∞

The first two types are discussed and the results are compared with the Draft Code of Practice for Prestressed Concrete.
The strength of reinforced concrete beams in shear
Authors: Sunderland A.
Published: July 2012

Summary:

The determination of the magnitude and distribution of the shearing stresses in reinforced concrete beams is one of the most difficult problems that faces designers at the present time. A research programme has been pursued for some two years in the Civil Engineering Laboratories of Leeds University and this paper deals with the results of tests on 39 beams designed to fail in shear or diagonal tension. Many factors influence the resistance of reinforced concrete in shear and the factors investigated so far are the effects of variations in (a) spacing of vertical stirrups and percentage web reinforcement, (b) ratio of depth of beam to the span.

It is seen that vertical stirrups, even with spacings a little greater than the moment arm, always increase the ultimate shearing loads, the effectiveness of the stirrups falling gradually when the spacing exceeds about one-half the moment arm. The widths of inclined cracks in beams with mild steel vertical stirrups were less than 0·005 in. at a stress of 18,000 lb. per sq. in. and with square twisted steel stirrups about 0·006 in. at 25,000 lb. per sq. in. Vertical stirrups usually attain their ultimate strengths and, in shallow beams, a load factor of 2·5 is satisfactory. The capacity of doubly-reinforced beams to resist shear, in virtue of an action analagous to that of an open-frame girder, is considerable. A comparison is made of the observed shearing failing loads with the loads derived from British and American Codes of Practice from which it is seen that the present British Code of Practice is too conservative.
An investigation into the cause of cracking in a reinforced concrete silo containing cement
Authors: Rowe R. E.
Published: July 2012

Summary

The paper describes a series of tests carried out to determine the cause of cracking in a reinforced concrete silo used for storing cement. The tests covered the location of the steel reinforcement and the measurement of the laps in the horizontal steel, the pressures exerted on the walls, and the temperature differential through the walls.

The cause of cracking was a combination of the effects of pressure in excess of that designed for, large temperature differentials through the walls of the silo, and a deficiency in reinforcing steel.

From the results obtained it is clear that Janssen's theory for the pressure exerted by granular materials on the walls of a container is inapplicable to cement. An alternative method of determining the pressures, based upon the experimental results, is put forward. The temperature differential through the walls was about 33°C during the tests and indicates that this factor must be considered in the design of a cement silo.

Finally the need is stressed for further tests on actual cement silos so that a more realistic method of design can be evolved.
Creep of lightweight concrete
Authors: Best C. H. , Polivka M.
Published: July 2012

Summary

Creep data covering periods of up to 18 months for concretes made with expanded-shale aggregates and having compressive strengths of 3,000 and 5,000 lb/in2 at 28 days are reported. These are compared with data for sand-gravel concretes of comparable strength. It was found that, contrary to current opinion, creep in lightweight concrete was essentially equal to or less than that in normal-weight concrete of comparable strength.

The aggregates used in this investigation are typical of expanded-shale aggregates and natural sand-gravel aggregates available on the west coast of the United States, and the results may, therefore, not be directly applicable to materials available in other countries or in other parts of the United States. However, since the three expanded-shale aggregates used are typical of products that can be obtained by sintering clays and shales to incipient fusion, the results reported should be generally applicable to concretes containing such aggregates.

A brief description of the hydraulic loading equipment used in the creep tests is included. The equipment, performed satisfactorily throughout this investigation with very little maintenance; it may be expected to perform similarly at any stress level normally encountered in creep studies. Some brief comments relative to the merit of current techniques for studying creep in concrete are made, and a new approach to the problem is suggested.
The shrinkage and creep of concrete
Authors: Lyse Inge
Published: July 2012

Summary

This paper describes an investigation made at the Laboratoires du Bâtiment et des Travaux Publics at Paris into the principal factors influencing the creep and shrinkage of concrete. The main conclusions drawn are that both creep and shrinkage are directly proportional to the amount of cement paste in the concrete, that creep is directly proportional to the sustained stress, and that both creep and shrinkage are greatly affected by the relative humidity of the atmosphere. Three equations are given from which shrinkage, creep, and total shortening can be calculated.