bluuebunny/crossref_metadata_2025 huggingface dataset:
Pro-adrenomedullin usefulness in the management of children with community-acquired pneumonia, a preliminar prospective observational study
Authors: Sardà Sánchez Marta , Hernández Joan Calzada , Hernández-Bou Susanna , Teruel Gemma Claret , Rodríguez Jesús Velasco , Cubells Carles Luaces
Published: July 2012

Background

In adult population with community acquired pneumonia high levels of pro-adrenomedullin (pro-ADM) have been shown to be predictors of worse prognosis. The role of this biomarker in pediatric patients had not been analyzed to date. The objective of this study is to know the levels of pro-ADM in children with community acquired pneumonia (CAP) and analyze the relation between these levels and the patients’ prognosis.

Findings

Prospective observational study including patients attended in the emergency service (January to October 2009) admitted to hospital with CAP and no complications at admission. The values for pro-ADM were analyzed in relation to: need for oxygen therapy, duration of oxygen therapy, fever and antibiotic therapy, complications, admission to the intensive care unit, and length of hospital stay. Fifty patients were included. Ten presented complications (7 pleural effusion). The median level of pro-ADM was 1.0065 nmol/L (range 0.3715 to 7.2840 nmol/L). The patients presenting complications had higher levels of pro-ADM (2.3190 vs. 1.1758 nmol/L, p = 0.013). Specifically, the presence of pleural effusion was associated with higher levels of pro-ADM (2.9440 vs. 1.1373 nmol/L, p < 0.001).

Conclusions

In our sample of patients admitted to hospital with CAP, pro-ADM levels are related to the development of complications during hospitalization.
Inferences from Genomic Models in Stratified Populations
Authors: Janss Luc , de los Campos Gustavo , Sheehan Nuala , Sorensen Daniel
Published: July 2012

Unaccounted population stratification can lead to spurious associations in genome-wide association studies (GWAS) and in this context several methods have been proposed to deal with this problem. An alternative line of research uses whole-genome random regression (WGRR) models that fit all markers simultaneously. Important objectives in WGRR studies are to estimate the proportion of variance accounted for by the markers, the effect of individual markers, prediction of genetic values for complex traits, and prediction of genetic risk of diseases. Proposals to account for stratification in this context are unsatisfactory. Here we address this problem and describe a reparameterization of a WGRR model, based on an eigenvalue decomposition, for simultaneous inference of parameters and unobserved population structure. This allows estimation of genomic parameters with and without inclusion of marker-derived eigenvectors that account for stratification. The method is illustrated with grain yield in wheat typed for 1279 genetic markers, and with height, HDL cholesterol and systolic blood pressure from the British 1958 cohort study typed for 1 million SNP genotypes. Both sets of data show signs of population structure but with different consequences on inferences. The method is compared to an advocated approach consisting of including eigenvectors as fixed-effect covariates in a WGRR model. We show that this approach, used in the context of WGRR models, is ill posed and illustrate the advantages of the proposed model. In summary, our method permits a unified approach to the study of population structure and inference of parameters, is computationally efficient, and is easy to implement.
Some experiments on the compaction of concrete by vibration
Authors: Davies R. D.
Published: July 2012

Summary:

Cubes of very dry concrete, of mix proportions suitable for small prestressed beams,were compacted by vibration of various types, frequencies and amplitudes. The crushing strengths obtained are analyzed statistically.
Changes in bond strength caused by re-vibration of concrete and the vibration of reinforcement
Authors: Larnach William J.
Published: July 2012

Summary

By means of pull-out tests the effects of (1) re-vibration of partially set concrete in which reinforcement is located, (2) the application of vibration directly to the reinforcement during concrete placement and (3) the direct vibration of bars protruding from partially set concrete are studied. The results indicate that treatments (2) and (3) have little effect, and that treatment (1) may result in a decrease of about 30 per cent in the average bond stress for the horizontal reinforcement used.
A note on the nomenclature of the calcium silicate hydrates
Authors: Bogue R. H.
Published: July 2012

Summary

Because of the ambiguity in the designation of a number of the calcium silicate hydrates, a system is proposed to overcome the confusion. Tables are presented listing the calcium silicate hydrates generally conceded to be distinct phases, together with previous designations, mineral names, method of preparation when produced synthetically, and some of the optical and crystallographical characteristics.
Design of longitudinal cables in circumferentially wound prestressed concrete tanks
Authors: Curtis A. R. , Cowan H. J.
Published: July 2012

Summary

During the circumferential prestressing of a cylindrical tank, longitudinal bending stresses are set up; if cracks are to be avoided, the tensile stresses must be eliminated by a longitudinal prestress. The paper develops a theory by which the magnitude of this longitudinal prestress may be determined. It is assumed that the thickness of the wall is small compared with the diameter of the cylinder, and that the concrete behaves elastically.
The ultimate strength of pre-tensioned prestressed concrete failing in bond
Authors: Hognestad Eivind , Janney Jack R.
Published: July 2012

Summary

Bond stresses between concrete and steel may perform the function of transferring prestress from the prestressing tendon to the concrete, or may arise due to shear or due to flexural cracks. The last two are difficult to separate quantitatively, and may be referred to together as flexural bond stresses.

The paper discusses the results of investigations into bond carried out at the Portland Cement Association Laboratories near Chicago. There were two major series of tests; one series was concerned with the prestress transfer bond, and the other with the flexural bond stresses.

The first series of tests was performed on prisms 2 × 2 in. in cross-section and 72 or 96 in. long, with a single pretensioned wire located at the longitudinal axis. Both the size of wire and its surface condition were varied. Strains of the wires and the concrete were measured by electric resistance strain gauges.

The flexural bond stresses were measured on centre-loaded 6 × 10 in. beams, the major variables being the size of wire, its surface condition and the degree of prestress.

The results of the tests are given in graphical form, and the relationship between the bond strength and the ultimate strength of pre-tensioned concrete is discussed.
Experiments on the creep of concrete under two-dimensional stressing
Authors: Ross A. D.
Published: July 2012

Summary

The tests were designed to investigate the creep of concrete specimens under (a) two compressive principal stresses, and (b) one compressive and one tensile principal stress. The equipment for producing the stresses and the gauges for measuring the strains are described. Results are presented which suggest that creeps develop in the principal directions with magniTudes generally of the same order as the corresponding creeps under simple stress. Poisson's ratio for creep strains appears to be negligible.
Experiments on the strength of reinforced and prestressed concrete beams and of concrete-encased steel joists in combined bending and torsion
Authors: Cowan Henry J. , Armstrong Stewart
Published: July 2012

Summary

A series of reinforced and prestressed concrete beams and concrete-encased steel joists was tested in combined bending and torsion, with ratios of bending moment to twisting moment varying from pure bending to pure torsion. In all, 33 full-size beams were tested. Measurements of defiexions and strains due to bending and to torsion were made at selected points. The agreement between theory and experiment was generally good.

The torsional strength of concrete can be augmented by suitable shear reinforcement. The resistance of the reinforced concrete beams to torsion, however, still depends on the tensile strength of the concrete; it is not therefore possible to gain an increase in strength comparable with that resulting from the addition of tension reinforcement to a plain concrete beam subject to bending. On the other hand the insertion of even a small quamity of shear reinforcement turns the abrupt torsion failure of plain concrete into a gradualfailure accompanied by considerable cracking and deformation.

The torsional strength of a concrete-encased steel beam is approximately the same as that of a similar plain concrete beam. The “1” shape is fundamentally a weak one in torsion and the concrete encasement therefore results in a considerable increase in the torsional strength of the steel joist, provided that the joist is surrounded with a nominal amount of stirrup reinforcement or expanded metal to ensure that the steel and concrete act together.

Very large increases in torsional strength can be obtained by prestressing, since the initial prestress in compression must be overcome before the concrete can be stressed in tension. The prestressing force, however, increases the rate at which cracks propagate during failure, which therefore tends to assume a violent character.

Two distinct types of failure can be distinguished in beams subject to combined bending and torsion. A primary torsion failure occurs with a cleavage fracture normal to the direction of the principal tension. It is governed by the criterion of a constant maximum tensile stress. In bending, tension failure is prevented by the steel, and a primary bending failure therefore results in the crushing of the concrete on the compression face.

In reinforced concrete and concrete-encased steel beams the addition of bending increases the resistance to torsion.

The paper concludes with detailed recommendations for the design of reinforced and prestressed concrete beams and concrete-encased rolled steel joists in torsion, and in combined bending and torsion.
The effect of allowing concrete to dry before it has fully cured
Authors: Waters T.
Published: July 2012

Summary

This report gives the results of experiments done to find the effect upon strength of curing concrete in an absolutely or partially dry state. It is normal practice to keep concrete wet for four or five days after placing. For example on page 85 of “Specification 1952” is stated that:

“It is important that concrete should be kept damp for as long a period as practicable. This can be achieved by sprinkling, covering with damp sacks or any similar method, and, except in the case of high alumina cements, is considerably assisted by leaving damp shuttering in position as long as possible. If concrete is allowed to dry out at an early age the strength and permeability will be impaired and the shrinkage increased.”

The results of the present experiments show, however, that as far as strength is concerned the curing can be done at any time. Thus if the concrete is allowed to become dry for a period and is then re-wetted, it will continue to increase in strength as though the dry period had never existed.

The experimental work was done in two parts, the first to find the eflect of curing concrete in absolutely dry air, and the second in ordinary room atmosphere.
The ultimate strength and deformation of plastic hinges in reinforced concrete frameworks
Authors: Chan W. W. L.
Published: July 2012

Summary

By comparing the idealized assumption of plastic hinges concentrated at points and the actual spread of plasticity, the validity of the plastic hinge theory of reinforced concrete frameworks is verified and the expressions for calculating the available plastic rotations are derived. Tests show that lateral binding considerably increases the stress-strain capacity of reinforced concrete sections, and this can be employed to increase the rotation of critical plastic hinge zones. Further tests on struts provide information on the curvature distribution along plastic zones.
The laboratory use of bonded-wire electrical-resistance strain gauges on concrete at the Building Research Station
Authors: Cooke R. W. , Seddon A. E.
Published: July 2012

Summary

A description is given of methods and experience of using bonded-wire electrical-resistance strain gauges on concrete, mainly in short-term static loading tests. Precautions required to obtain reliable strain data and the accuracy of surface strain measurement are discussed on the basis of tests and experience, and the merits of mounting the gauges on brass foil are considered. Some information is also included on the questions of a suitable gauge length and the long-term instability of the gauges on concrete.
The ultimate strength of reinforced concrete beams in shear
Authors: Jones Royston
Published: July 2012

Summary

This paper summarizes conclusions drawn from tests on a number of beams of identical dimensions but of different concrete strengths and from a re-assessment of tests on beams of various dimensions reported by Sunderland(1)* and Wilby.(2)* The limitations of recently advanced shearcompression moment theories are demonstrated and a new expression is developed on similar principles.

A theoretical analysis of shrinkage stresses is developed to predict the loads at the appearance of bending and diagonal tension cracks, whereby it is shown that the shrinkage stresses may have an effect on the ultimate shear resistance.

Three divided beams were tested in an attempt to measure directly the separate contributions to shear resistance made by the concrete, the web reinforcement, and the longitudinal reinforcement. In these beams a gap was pre-formed on the expected line of the diagonal tension crack and the concrete in the compression zone was replaced by a mechanical device to record direct force and shear force. The results are examined in relation to a mathematical analysis of the shear force resisted by the dowel action of the longitudinal reinforcement.
Lightweight calcium silicate hydrate: some mix and strength characteristics
Authors: Taylor W. H. , Moorehead D. R.
Published: July 2012

Summary

Developments in Europe and America suggest that lightweight calcium silicate hydrate oiTers much promise for building purposes, although the amount of published technical data is limited. This paper presents the results of a study of some physical characteristics of autoclaved products, relating to mix design and compressive strength, using five grades of silica flour that vary widely in specific surface area.

It is shown that for each of the grades of silica flour there is a certain value of the lime/silica ratio at which the ratio of the compressive strength to the unit weight reaches a maximum. A limited number of results, obtained under an arbitrary set of conditions without batch replication, show approximately linear relations between (a) the unit weight of dry products and the water/solids ratio of mixes, (b) the ratio of the compressive strength to the unit weight of dry products and the water/solids ratio of mixes, and (c) the lime/silica ratio (for maximum compressive strength) and the specific surface area of the silica flour used.
Unbroken tobermorite crystals from hydrated cement
Authors: Gaze R. , Robertson Roberts H. S.
Published: July 2012

Summary

Electron-micrographs of cement crystals have given clear indication of the presence of tobermorite in the form of foils. The foils illustrated are estimated to be of the order of two molecules in thickness, which other workers have indicated to be the smallest possible size for tobermorite.
The effect of coarse aggregate on the mode of failure of concrete in compression and flexure
Authors: Jones R. , Kaplan M. F.
Published: July 2012

Summary

Experiments have been made to determine the flexural and compressive strengths of concretes containing thirteen different coarse aggregates. In the compression tests, observations were made by an ultrasonic pulse technique to detect the onset of cracking prior to failure.

The main results were as follows. Concretes containing smooth gravels began to crack at lower compressive stresses than did concretes containing coarser-textured aggregate. The compressive strengths did not show such appreciable differences. Concretes which best resisted pre-cracking in compression also gave highest flexural strengths. The relation between the flexural strength of the concrete and the stress at which cracks first occurred in compression was independent of the type of coarse aggregate; no such unique relation existed between flexural strength and ultimate compressive strength. Tentative conclusions are drawn on the mode of failure of the concrete as follows.

Pre-cracking in a cube when tested in compression probably arises from local breakdown in the adhesion between the coarse aggregate and the cement. The average compressive stress at which the first cracks occur is determined by those properties of the aggregate which influence the aggregate-cement bond.

Pre-cracking in compression does not lead to the immediate fracture of the concrete specimen. A contribution to the ultimate strength is provided by the mechanical interlocking of the coarse aggregate after pre-cracking has occurred. Thus the compressive strength of concrete is usually greater than the compressive strength of its comparable mortar.

In flexure, pre-cracking causes fracture of the concrete specimen and the only properties of the coarse aggregate which influence the flexural strength are those which appear to determine the aggregate-cement bond. In general the flexural strength of concrete is lower than the flexural strength of the corresponding mortar.
Some experiments on the applicability of the principle of superposition to the strains of concrete subjected to changes of stress, with particular reference to prestressed concrete
Authors: Davies R. D.
Published: July 2012

Summary

The paper describes experiments to test the validity of McHenry's hypothesis that the principle of superposition can be applied to the strains, including the creep strains, of concrete subjected to changes of stress. It is concluded that, although the hypothesis is by no means strictly correct, it is nearer the truth than the assumption that change of strain is proportional to change of stress. The application of the hypothesis to prestressed beams under sustained loads is considered with reference to the distribution of stress on a cross-section and to bending.
The relation between standard deviation and mean strength of concrete test cubes
Authors: Neville A. M.
Published: July 2012

Summary

Tests on laboratory-made concrete of various mix proportions, types of cement, and ages at test indicate that, for a constant degree of control, the standard deviation within a batch is directly proportional to the mean strength of the concrete. A similar relation applies to the standard deviation between batches. These relations do not hold good for very low strengths—below about 1,500 lb/in2.

An examination of field data, carefully separated according to the degree of control exercised, suggests that for site-made concrete also the standard deviation increases with the increase in the mean strength. Thus the present practice of designing mixes on the basis of a constant coefficient of variation, as recommended by Road Note No. 4, is believed to be satisfactory.
The relation between ultrasonic pulse velocity and the compressive strength of concretes having the same workability but different mix proportions
Authors: Kaplan M. F.
Published: July 2012

Summary

Experiments have been made to investigate whether, for concrete of a given workability, the relation hetween ultrasonic pulse velocity and compressive strength is independent of variations in age and in mix proportions (i.e. aggregate/cement and water/cement ratios).

It is concluded that, for concrete made of the same type of material, curves relating pulse velocity to compressive strength may be drawn for concrete of the same workability but different mix proportions, provided that the tests are done at the same age. When tests are done at different ages the relation is dependent on both mix proportions and age. This dependence is, however, not so apparent at low compressive strengths.
An examination of the stresses in the anchorage zone of a post-tensioned prestressed concrete beam
Authors: Douglas D. J. , Trahair N. S.
Published: July 2012

Summary

The work described is the result of investigations carried out in the Department of Civil Engineering of the University of Sydney in an attempt to determine the effect of high concentrations of stress in the anchorage zone of a prestressed concrete beam. The problem was idealized as that of the stress distribution due to the application ofa circular concentrated load acting at one end of a concrete cylinder, the theoretical analysis and experimental procedure being in this way simplified. A mathematical analysis of a three-dimensional case to determine the stresses throughout the anchorage zone is described and the results are compared with those of other writers. In a series of tests designed to verify the theoretical analysis, the loads required to cause failure were much greater than those predicted on the basis of current theories of failure and on the assumption of elastic behaviour. Further experimental work involving measurement by electrical resistance strain gauges of the surface strains showed good agreement with strains predicted theoretically. Attention is called to the fact that the tensile strains measured corresponded to stresses of approximately four times the ultimate tensile stress of the concrete as determined by the Brazilian method of testing.
Hydrothermal reactions between lime and aggregate fines
Authors: Midgley H. G. , Chopra S. K.
Published: July 2012

Summary

Hydrothermal reactions between lime and aggregate such as pulverized fuel ash, expanded colliery shale, ground quartz, granulated and foamed blastfurnace slag have been studied. The compressive strength and mineralogy have been determined for various mixtures of lime and aggregate fines autoclaved at 160 lb/in2 for 2,6,16 and 48 hours. The cementitious minerals identified were: tobermorite (calcium silicate hydrate) and a hydrogarnet when the aggregate was pulverized fuel ash or shale; tobermorite and zonotlite when it was quartz; and poorly crystalline tobermorite (tobermorite gel), dicalcium silicate alpha-hydrate and a hydrogarnet when the aggregate was slag glass.

When dicalcium silicate alpha-hydrate was the predominant phase, the strength of the blocks was lower than when tobermorite was the main phase.
Hydration of tricalcium aluminate with lignosulphonate additives
Authors: Young J. F.
Published: July 2012

Summary

Lignosulphonates modify the hydration of tricalcium aluminate: acicular crystals form instead of the usual hexagonal plates, and by X-ray diffraction, DTA* and optical data it has been shown that these can represent more than one hydration product. The differences in reaction products are attributed to small changes in hydration conditions. In pastes of tricalcium aluminate, C2AH8† and C4AH13 crystallize with a new crystal habit, rather than forming a new hydrate. Current theories explaining the effect of lignosulphonates on the mechanical strengths of concrete are discussed.
Effect of calcium chloride on the durability of pre-tensioned wire in prestressed concrete
Authors: Roberts M. H.
Published: July 2012

Summary

This paper gives in the first place an account of investigations which were made to determine the extent to which calcium chloride may be present in the free state in concrete at various temperatures, since this will have a bearing on the extent of corrosion of embedded steel. It has been concluded that while there is a tendency for a large proportion of the added calcium chloride to react with the hydrating cement at normal temperatures, the residual small amount of free chloride always retained in solution will give an appreciable chloride concentration in solution and will cause a certain amount of corrosion of embedded steel. The amount of free chloride in solution is influenced by the composition of the cement, and will increase with an increase in the amount of calcium chloride added and with increasing temperature.

These conclusions offer a reasonable interpretation of some of the findings of the second part of the paper which covers a direct study of corrosion of high-tensile steel embedded in different concretes containing calcium chloride. The present results indicate that with good concrete practice in mix design, depth of cover, and specification of materials, the additional corrosion induced by the use of flake calcium chloride up to about 2 % by weight of the cement in dense normally cured ordinary Portland cement concrete will have no structural significance. However, corrosion is greater under other conditions, and it appears that the degree of corrosion obtained in the presence of calcium chloride will depend on a number of factors, such as the quality of the concrete and adequacy of the casting procedures, the composition of the cement, the amount of calcium chloride added, the conditions of curing and storage of the concrete, and the diameter and initial surface condition of the steel wires.
The influence of support conditions on the behaviour of square concrete tanks
Authors: Davies J. D.
Published: July 2012

Summary

The paper describes a theoretical and experimental investigation of the structural behaviour of a tank in the shape of a cube under six different support conditions which include point, line and distributed reaction patterns. It is demonstrated that the method of supporting the tank has a significant effect upon the magnitude and distribution of the bending moments, particularly those values used in the design of the sections of the wall panels and floor slabs of tanks. The accuracy of the analytical predictions is checked by deflexion and curvature measurements taken on a Perspex model tank with appropriately simulated support conditions. Generally, there is a good correlation between the theoretical and experimental results.
An investigation of the unit weight of concrete
Authors: Popovics Sándor
Published: July 2012

Summary

Experimental results are presented which show the effects of cement content, air content, slump, aggregate grading and specific gravities on the unit weight of fresh and hardened concrete. With a knowledge of these effects an intelligent and resolute selection of the different proportions for a specified concrete density can be made. Formulae are presented which show the relations between the concrete composition and the unit weight of the fresh and hardened concrete. These formulae are applicable even when the mineral aggregate is a mixture of two or more materials of different specific gravities. The form of the equations presented is relatively simple considering the large number of variables involved. Values computed from the formulae show good agreement with experimental results. These formulae thus provide a new and easy method for selecting the most economical concrete composition for a given unit weight of concrete.
The creep of concrete under uniaxial tension
Authors: Illston J. M.
Published: July 2012

Summary

Tests are reported on the strain of concrete under sustained uniaxial tensile stress. The effects on this strain of the level of stress, the time under load, the age of loading and the humidity of storage are examined and compared with the behaviour under compressive stress. In general, the influence of the factors was much the same for both senses of stress but differences were found in the rates of creep, in the magnitudes of the strains under saturated conditions of storage and in the shape of the recovery curve after removal of load. Finally, two further tests are reported which indicate that the strains under a cycle of tension or compression are unaffected by a previous cycle under a stress of opposite sense.
Effect of the arrangement of reinforcement on the behaviour of reinforced concrete slabs
Authors: Taylor R. , Maher D. R. H. , Hayes B.
Published: July 2012

Summary

Tests on 10 two-way spanning, simply supported, reinforced concrete slabs are reported. The slabs were designed to have similar ultimate loads, but different arrangements of the reinforcement were adopted. The span/depth ratio was also varied. All slabs sustained loads higher than the theoretical collapse load given by the yield-line theory. The increased carrying capacity, due partly to tensile membrane action, ranged from 26 to 80 % depending on the arrangement of the reinforcement.
Further evidence relating to the ‘new hypothesis of sulphate expansion’
Authors: Chatterji S. , Jeffery J. W.
Published: July 2012

Summary

A recently proposed mechanism of sulphate expansion of cements has been subjected to further tests. According to the proposed mechanism, an addition of CaCO3 to Portland cement should result in a better performance in sulphate solution. To test this, a single batch of Portland cement was used neat and in two 9:1 ‘cement’ mixtures madefrom cement and CaCO3 and cement and quartz respectively. A series of 1:4 ‘cement’ :sand mortar prisms was made with the neat cement and with each of the two ‘cement’ mixtures. After water curing, these prisms were exposed to sulphate solutions, and their expansion was measured. The results showed that the mixture of CaCO3 and Portland cement performed better than both the neat Portland cement and the mixture of quartz and Portland cement, thereby corroborating the proposed mechanism of sulphate expansion. The significance of these results for other properties of Portland cement is also discussed.
A Layered Approach to Raising Public Awareness of Macular Degeneration in Australia
Authors: Heraghty Julie , Cummins Robert
Published: July 2012

Between 2007 and 2011, the Australian Macular Degeneration Foundation conducted a multifaceted campaign to increase public awareness of macular degeneration. Regular national polls conducted by an independent social research company have shown that awareness of macular degeneration increased from 47% to 80% in Australians aged 16 years or older and from 58% to 92% in those aged 50 years or older. The percentage of people aged 50 years or older who reported having had their macula checked in the 2 years prior to the survey increased from 33% to 70% from 2007 to 2011. Other measures, including analysis of Medicare data, have confirmed the success of the campaign.
Initial evidence from a new database on capital market restrictions
Authors: El-Shagi Makram
Published: July 2012

One of the key obstacles to the empirical analysis of capital controls has
been the unavailability of a detailed set of indicators for controls that
cover a broad set of countries over a range of years. In this paper, we
propose a new set of indicators derived from the Annual Reports on Exchange
Arrangements and Export Restrictions. Contrary to most earlier attempts to
construct control indicators from this source, our set of indices allows one
to analyze the control intensity separately for inflow, outflow and
repatriation controls. An additional set of indicators features information
on the institutional design of controls. At first glance, the data show that
the financial crisis caused a surge in capital market restrictions, most
notably concerning the derivatives market. This reflex, which is not
justified by the scarce empirical evidence on the success of controls, shows
the importance of having a valid measure to allow an econometrically sound
policy evaluation in this field. The data are available from the author upon
request.
Does Gibrat’s law hold in the insurance industry of china? A test with sequential panel selection method
Authors: Pan Guochen , Chen Sen-Sung , Chang Tsangyao
Published: July 2012

This study applies the Sequential Panel Selection Method to investigate
whether the growth rate of total insurance premium is independent of their
size, as postulated by Robert Gibrat?s (1931) Law of Proportionate Effects.
Time-series data for the total insurance premium of 35 insurance companies in
China during the December 2005 to May 2011 period are used. Since other
panel-based unit root tests are joint tests of a unit root for all members of
a panel and are incapable of determining the mix of I(0) and I(1) series in a
panel setting, the SPSM, proposed by Georgios Chortareas and George
Kapetanios (2009), classifies a whole panel into a group of stationary series
and a group of non-stationary series. In doing so, we can clearly identify
how many and which series in the panel are stationary processes. The
empirical results from the SPSM tests unequivocally indicate that Gibrat?s
Law is only valid for one of these 35 companies studied here. Our study has
important policy implications for insurance regulation, insurance market
construction, and policyholder protection.
The phase equilibrium in a Lennard-Jones fluid: Possible applications in astrophysics
Authors: Celebonovic V.
Published: July 2012

Using standard thermodynamics and previous results of the author, this paper
aims to discuss the conditions for phase equilibrium in a Lennard-Jones
fluid. Possibilities for astrophysical applications of the obtained results
are discussed to some extent, including an unexpected application - in
physics of extremely dense matter concerning studies of neutron stars.
Prognostic Value of Resting Heart Rate on Cardiovascular and Renal Outcomes in Type 2 Diabetic Patients
Authors: Miot Aurelie , Ragot Stéphanie , Hammi Wala , Saulnier Pierre-Jean , Sosner Philippe , Piguel Xavier , Torremocha Florence , Marechaud Richard , Hadjadj Samy
Published: July 2012

OBJECTIVE

Epidemiological studies and randomized clinical trials have demonstrated in various populations that resting heart rate (RHR) was an independent predictor of cardiovascular (CV) risk and all-cause mortality. However, few data specifically evaluated the relationship between RHR and long-term CV and renal complications in a large population of type 2 diabetic (T2D) patients.

RESEARCH DESIGN AND METHODS

We performed a single-center, prospective analysis in 1,088 T2D patients. RHR was determined at baseline by electrocardiogram. The primary outcome was a composite criterion of CV and renal morbi-mortality (CV death, nonfatal myocardial infarction and/or stroke, hospitalization for heart failure, renal replacement therapy), which was adjusted for death from non-CV cause as a competing event. The secondary outcome was a renal composite criterion (renal replacement therapy or doubling of baseline serum creatinine) adjusted for all-cause death as a competing event.

RESULTS

During median follow-up of 4.2 years, 253 patients (23%) and 62 patients (6%) experienced the primary and secondary outcomes, respectively. In the subgroup of patients with CV disease history at baseline (n = 336), RHR was found to be associated with the incidence of primary outcome (P = 0.0002) but also with renal risk alone, adjusted for all-cause death as a competing event (secondary outcome; P < 0.0001). In patients without history of CV disease, no relation was found between RHR and the incidence of CV and/or renal events.

CONCLUSIONS

In the real-life setting, RHR constitutes an easy and less time-consuming factor that would permit identification of CV disease diabetic patients with an increased risk for long-term CV and renal complications.
Childhood Nutrition in Predicting Metabolic Syndrome in Adults
Authors: Jääskeläinen Paula , Magnussen Costan G. , Pahkala Katja , Mikkilä Vera , Kähönen Mika , Sabin Matthew A. , Fogelholm Mikael , Hutri-Kähönen Nina , Taittonen Leena , Telama Risto , Laitinen Tomi , Jokinen Eero , Lehtimäki Terho , Viikari Jorma S.A. , Raitakari Olli T. , Juonala Markus
Published: July 2012

OBJECTIVE

Our aim was to study the associations of childhood lifestyle factors (the frequency of consumption of vegetables, fruit, fish, and meat, butter use on bread, and physical activity) with the metabolic syndrome (MetS) in adulthood.

RESEARCH DESIGN AND METHODS

The study cohort consisted of 2,128 individuals, 3–18 years of age at the baseline, with a follow-up time of 27 years. We used the average of lifestyle factor measurements taken in 1980, 1983, and 1986 in the analyses. Childhood dietary factors and physical activity were assessed by self-reported questionnaires, and a harmonized definition of MetS was used as the adult outcome.

RESULTS

Childhood vegetable consumption frequency was inversely associated with adult MetS (odds ratio [OR] 0.86 [95% CI 0.77–0.97], P = 0.02) in a multivariable analysis adjusted with age, sex, childhood metabolic risk factors (lipids, systolic blood pressure, insulin, BMI, and C-reactive protein), family history of type 2 diabetes and hypertension, and socioeconomic status. The association remained even after adjustment for adulthood vegetable consumption. Associations with the other childhood lifestyle factors were not found. Of the individual components of MetS, decreased frequency of childhood vegetable consumption predicted high blood pressure (0.88 [0.80–0.98], P = 0.01) and a high triglyceride value (0.88 [0.79–0.99], P = 0.03) after adjustment for the above-mentioned risk factors.

CONCLUSIONS

Childhood vegetable consumption frequency is inversely associated with MetS in adulthood. Our findings suggest that a higher intake of vegetables in childhood may have a protective effect on MetS in adulthood.
Effect of Pramlintide on Prandial Glycemic Excursions During Closed-Loop Control in Adolescents and Young Adults With Type 1 Diabetes
Authors: Weinzimer Stuart A. , Sherr Jennifer L. , Cengiz Eda , Kim Grace , Ruiz Jessica L. , Carria Lori , Voskanyan Gayane , Roy Anirban , Tamborlane William V.
Published: July 2012

OBJECTIVE

Even under closed-loop (CL) conditions, meal-related blood glucose (BG) excursions frequently exceed target levels as a result of delays in absorption of insulin from the subcutaneous site of infusion. We hypothesized that delaying gastric emptying with preprandial injections of pramlintide would improve postprandial glycemia by allowing a better match between carbohydrate and insulin absorptions.

RESEARCH DESIGN AND METHODS

Eight subjects (4 female; age, 15–28 years; A1C, 7.5 ± 0.7%) were studied for 48 h on a CL insulin-delivery system with a proportional integral derivative algorithm with insulin feedback: 24 h on CL control alone (CL) and 24 h on CL control plus 30-μg premeal injections of pramlintide (CLP). Target glucose was set at 120 mg/dL; timing and contents of meals were identical on both study days. No premeal manual boluses were given. Differences in reference BG excursions, defined as the incremental glucose rise from premeal to peak, were compared between conditions for each meal.

RESULTS

CLP was associated with overall delayed time to peak BG (2.5 ± 0.9 vs. 1.5 ± 0.5 h; P < 0.0001) and reduced magnitude of glycemic excursion (88 ± 42 vs. 113 ± 32 mg/dL; P = 0.006) compared with CL alone. Pramlintide effects on glycemic excursions were particularly evident at lunch and dinner, in association with higher premeal insulin concentrations at those mealtimes.

CONCLUSIONS

Pramlintide delayed the time to peak postprandial BG and reduced the magnitude of prandial BG excursions. Beneficial effects of pramlintide on CL may in part be related to higher premeal insulin levels at lunch and dinner compared with breakfast.
Pattern recognition methods as supplementary techniques for identification of salicylamide — cyclodextrins inclusion complexes
Authors: Kosecka-Judin Ewa , Wesolowski Marek , Paukszta Dominik
Published: July 2012

The objective of this study was to learn whether or not the pattern recognition methods, such as agglomerative cluster analysis (CA) and principal component analysis (PCA), can be used as supplementary techniques for identification of salicylamide (SAA) inclusion complexes with β-cyclodextrin (β-CD) and 2-hydroxypropyl-β-cyclodextrin (HP-β-CD). To do this, phase-solubility of SAA in the presence of the cyclodextrins was studied by the Higuchi-Connors method, which showed that the cyclodextrins enhanced the solubility of SAA in water as compared to that of the drug. Next, the solid phase complexes of the drug with β-CD and HP-β-CD were prepared by using the coprecipitation, precipitation-evaporation, and kneading methods. Identification of the inclusion complexes was performed by using thermal analysis, infrared spectroscopy, and wide angle X-ray scattering. Two multivariate statistical methods, CA and PCA, were used as the supplementary techniques for identification of the inclusion complexes. The results of the statistical analysis have shown that CA and PCA are helpful for interpretation of the thermoanalytical and spectral data. Moreover, these methods enabled proper classification of the products in all doubtful cases. They can be used as supplementary techniques to verify the conclusions of the above-mentioned standard methods.
Exploring the possibility of high-valent copper in models of copper proteins with a three-histidine copper-binding motif
Authors: Anamaria Imre , Mot Augustin , Silaghi-Dumitrescu Radu
Published: July 2012

An important function of many copper-containing proteins is activation of O2 and subsequent substrate oxidation. The Cu (III) oxidation state is generally considered to be less accessible because of the highly positive Cu (III)/Cu (II) redox potentials with typical amino acid ligands. Here, we employ density functional (DFT) calculations to explore to what extent copper (III) may be accessed in a biologically-relevant coordination environment around a mononuclear copper center, by breaking the oxygen-oxygen bond in a copper-(hydro) peroxide complex. In agreement with previous findings by Solomon and co-workers on copper models with related coordination patterns, the formally high-valent copper complex produced by O-O bond cleavage appears to harbor both oxidizing equivalents on the ligands. The potential energy surface for such a reaction reveals that with the three-histidine binding motif at the copper, O-O bond cleavage is not impossible, but rather disfavored thermodynamically.
Thermodynamic study of binary mixture of citric acid and tartaric acid
Authors: Meltzer Viorica , Pincu Elena
Published: July 2012

The solid — liquid phase equilibria for binary mixture of citric acid with tartaric acid were measured using differential scanning calorimetry. The phase diagram showed the existence a simple eutectic behavior. The thermal properties of this system as heat of mixing, entropy of fusion and excess thermodynamic functions were computed using enthalpy of fusion values. The composition of eutectic was determined using a Tammann diagram.
Synthesis, NMR characterization and reactivity of 1-silacyclohex-2-ene derivatives
Authors: Khan Ezzat , Wrackmeyer Bernd
Published: July 2012

The chloro functionality of allyldichlorosilane (HSiCl2(C3H5)) and allyldichloromethylsilane (MeSiCl2(C3H5)) were replaced by alkynyl groups and new compounds, allyldialkynylsilane 1 and allyldialkynylmethylsilane 2, were obtained. These silanes, which served as starting materials for the onward reactions, were purified by fractional distillation. They were further subjected to hydroboration with 9-BBN (9-borabicyclo[3.3.1]nonane) and were converted into 1-silacyclohex-2-ene derivatives 5 and 6. The competition between C≡C and C=C in the reaction was studied. The hydroborating reagent 9-BBN was expected to prefer terminal C=C bonds and to leave C≡C bond untouched. This hypothesis of preferable hydroboration was experimentally proved, and hence, 1-silacyclohex-2-ene derivatives were obtained in reasonably pure form. The reaction of allyldialkynylsilane 2 with one equivalent of 9-BBN affords 1-silacyclohex-2-ene bearing Si-C≡C-function, ready to be hydroborated further with one equivalent of 9-BBN. The obtained compound bears two C-B bonds, which are attractive synthones for further transformations. This study aims to highlight the chemistry of C-B and Si-H functional groups. All new compounds obtained were colorless air and moisture sensitive oils, and they were studied by multinuclear magnetic resonance spectroscopy (1H, 13C, 11B, 29Si NMR) in solution.
C12: The building block of hexagonal diamond
Authors: Banfalvi Gaspar
Published: July 2012

The crystalline structure of diamond may consist of C8, C10 or C12 building units. C8 was regarded as the building block of the hexagonal diamond also known as Lonsdaleite. Adamantane (C10H16) alicyclic hydrocarbon has the same arrangement of carbon atoms as the basic C10 unit of the cubic diamond lattice. C12 has five rings of mixed type, three of them in boat, two in chair conformation. Model building revealed that the C8 unit containing exclusively three rings in boat conformation does not exist. Further addition of carbon atoms to C8: a) results in C12 unit, b) allows the multiplication of C12 units, and c) by reducing the boat-to-chair ratio explains the hardness of the hexagonal diamond Lonsdaleite. The Lonsdaleite nucleus can be grown to special diamond grains with the outer atoms of the C12 building units replaced by different elements. This recognition can be utilized in the production of synthetic diamonds under high-pressure high-temperature conditions or in the chemical vapor deposition growth technique.
Influence of different templates on the morphology of mesoporous aluminas
Authors: Berger Daniela , Traistaru Gina , Matei Cristian
Published: July 2012

Mesoporous alumina has many environmental applications as catalysts support and adsorption or separation material. We studied the synthesis conditions for the mesoporous alumina formation from aluminum isopropoxide in the presence of anionic (lauric and stearic acid), cationic (cetyltrimethylammonium bromide, CTAB) and non-ionic (triblock poly(ethylene oxide)-poly(propylene oxide)-polyethyleneoxide, P123) templates. The X-ray diffraction data show that the alumina mesophases obtained at 550°C in the presence of fatty acids or P123 have amorphous walls, whereas the samples prepared at 500°C by using CTAB, in alkaline medium are crystalline with a γ-alumina structure. The solvothermal treatment caused the alumina mesophase with crystalline walls to be obtained at 550°C. The samples were investigated by nitrogen adsorption-desorption isotherms and scanning electron microscopy. The obtained alumina mesophases have specific surface areas in the range of 300–450 m2 g−1, narrow pore size distribution, and different morphology depending on the template used in the synthesis.
α-Amino acid-derived 2-phenylimidazoles with potential antimycobacterial activity
Authors: Cvejn Daniel , Klimešová Věra , Bureš Filip
Published: July 2012

α-Amino acid-derived 2-phenylimidazole derivatives were designed, synthesized, and further investigated as potential antimycobacterial agents. The synthesis of target imidazole derivatives involved the transformation of Cbz-protected α-amino acids (Ala, Val, Phe, Leu, iLe, and Pro) into α-diazoketones and α-bromoketones, respectively. Subsequent treatment of α-bromoketones with (4-nitro)benzamidine afforded imidazole derivatives bearing α-amino acid residue appended to the imidazole C4 and (4-nitro)phenyl ring in the position C2. Antimycobacterial activities of both series of compounds against M. tuberculosis, M. avium, and M. kansasii were screened and basic structure-activity relationships were further evaluated.