bluuebunny/crossref_metadata_2025 huggingface dataset:
FE homogenised limit analysis model for masonry structures
Authors: Milani Gabriele , Lourenço Paulo B.
Published: June 2011

A finite-element (FE) homogenised limit analysis model suitable for analysing masonry structures near collapse is applied to a real large-scale three-dimensional (3D) masonry building subjected to horizontal actions. In the model, masonry is substituted for a fictitious macroscopic homogeneous material. Masonry macroscopic mechanical properties are obtained by means of a recently presented equilibrated limit analysis approach performed on a suitable unit cell, which generates the entire structure by repetition. Masonry homogenised failure surfaces are then implemented in the 3D code outlined. With respect to previously presented models, the software allows analysis of real-scale buildings without the classic uncoupling of in-plane and out-of-plane actions. The possible presence of steel, reinforced concrete and ring beams is also considered by introducing two-node beam elements in the numerical model. A relevant 3D structural example (a masonry structure subjected to horizontal actions) is treated. Full sensitivity analyses and comparison with results obtained from commercial elasto-plastic software are also presented to validate the results of the proposed model.
Numerical prediction of dynamic response of RC beams
Authors: Haido J. H. , Abu-Bakar B. H. , Abdul-Razzak A. A. , Jayaprakash J.
Published: June 2011

In this study, an attempt has been made to develop a finite-element numerical procedure for the non-linear transient dynamic analysis of reinforced concrete (RC) beams. New material constitutive relationships have been employed depending on various experimental data. Eight-node serendipity degenerated plate elements have been used to represent the concrete beam elements. A layered approach was adopted to discretise the concrete and steel reinforcement through the thickness of the beam. Strain-hardening plasticity and elastic perfectly plastic models have been used to model the compressive behaviour of the concrete used in this study. Strain rate effect was included by assuming the dynamic yield function to be a function of the current strain rate in addition to being the total plastic strain. Geometrical non-linearity in the layered approach is considered in the mathematical model, which is based on the total Lagrangian approach taking into account Von Karman assumptions. A new model is used to consider the effect of tension stiffening in the cracked concrete. Steel reinforcement is considered as an elastic plastic material with linear strain hardening. Implicit Newmark with a corrector–predictor algorithm is employed for time integration of the equation of the motion. A computer program coded in MATLAB has been developed for the non-linear finite-element dynamic analysis of RC beams subjected to the dynamic loadings. Finally, various numerical examples validating the proposed formulation are given.
Fully coupled dynamic analysis of an earth dam
Authors: ELIA G. , AMOROSI A. , CHAN A.H.C. , KAVVADAS M.J.
Published: June 2011

The paper studies the seismic behaviour of an existing homogeneous earth dam using a fully coupled finite-element effective stress approach in conjunction with a recently developed multi-surface, elasto-plastic constitutive model for structured soils. The model is calibrated using laboratory test results for the embankment material and the foundation soils. The initial state variables (stress, hardening parameters) are determined by simulating a simplified geological history of the foundation soil, dam construction stages and reservoir impounding, prior to the application of the earthquake shaking at the bedrock level. The paper critically reviews the role of the constitutive model parameters, the hysteretic damping introduced by the model and the additional viscous damping parameters in the accumulation of permanent displacements and in the development and subsequent dissipation of excess pore water pressures due to the seismic loading. The analyses, carried out with reference to a set of earthquake records related to different return periods, show that the overall behaviour of the system in terms of displacements is characterised by a more enhanced deformation pattern of the downstream slope as compared with the upstream one. The large plastic strains accumulation induced throughout the shaking is followed by the development of excess pore water pressures inside the dam and the foundation deposit. Nonetheless, the results are indicative of a satisfactory dynamic performance of the dam, even when subjected to severe seismic loading conditions.
Application of a hyperbolic model to municipal solid waste
Authors: SINGH M.K. , FLEMING I.R.
Published: June 2011

An understanding of the stress–strain behaviour of landfilled waste is important in landfill design. Based on evaluation of numerous strain–strain curves obtained from triaxial compression testing of samples of municipal solid waste (MSW) ranging from fresh to degraded, it is proposed that the stress–strain behaviour of MSW under loading follows a non-linear elastic (hyperbolic) model. The hyperbolic model is typically described using σult and E, but can also be described using c′ and φ′ in conjunction with three other parameters (K, n and Rf). The use of the parameters K, n and Rf to describe the stress–strain behaviour may be particularly useful for MSW, because it is often difficult to obtain values of σult and E. Stress–strain data from 15 datasets comprising 57 individual triaxial tests have been compiled. These data originated both from published studies and from the authors' own laboratory testing of large intact and recompacted samples of MSW from three different landfills in Canada. Best-fit hyperbolic model parameters K, n and Rf were determined for 12 of these datasets (comprising 50 individual triaxial tests), and upper- and lower-bound values of K, n and Rf were determined for the 90% confidence level. By using these upper- and lower-bound values, the five-parameter hyperbolic model was effectively reduced to a two-parameter (c′–φ′) model. It is proposed that the resulting lower and upper bounds of the stress–strain curves plotted using the proposed lower and upper bounds of K, n and Rf in conjunction with site-specific c′–φ′ values can reasonably embrace the experimental strain–strain curves up to an axial strain of 20%, even given the significant variability of the waste samples considered. This approach is given further credence as it yields a reasonable prediction of the stress–strain behaviour when compared with the last three datasets (comprising seven individual triaxial tests), which had not been included in the statistical analysis.
Photoelastic and photographic study of a granular material
Authors: LESNIEWSKA D. , MUIR WOOD D.
Published: June 2011

Glass ballotini can be used as a special granular material that reveals information about stress conditions when viewed using polarised light. Simultaneously, techniques for observing displacement fields can be used to produce information about internal strains. The combination of photoelastic and photographic observation has potential for extending knowledge of internal conditions in two-dimensional samples of granular material. The procedures described in this note indicate some interesting possibilities for experimental soil mechanics. The use of digital photography with polarised light permits incremental results to be obtained from the photoelastic images. The use of digital photography in non-polarised light with particle image velocimetry analysis gives the opportunity to obtain experimental displacement and strain fields with great accuracy and local detail. The use of standard image processing and graphics software permits precise comparison of features of the incremental strain and stress fields by superimposing corresponding images.
Slope stability analysis and discontinuous slope failure simulation by elasto-plastic smoothed particle hydrodynamics (SPH)
Authors: BUI H.H. , FUKAGAWA R. , SAKO K. , WELLS J.C.
Published: June 2011

Most slope stability analyses have employed limit equilibrium methods (LEMs) or the finite-element method (FEM) as the standard approach. However, slope instability is often accompanied by discontinuous failure of the soil, which cannot be modelled by either LEMs or FEM. To overcome this limitation, this paper presents an extension of the smoothed particle hydrodynamics (SPH) method to evaluate the stability of a slope, and to simulate the post-failure behaviour of soil. For the slope stability analysis, the shear strength reduction technique with a modified failure criterion for distinguishing convergent from non-convergent solutions is applied to estimate the safety factor of a slope, and the critical slip surface is determined from a contour plot of accumulated plastic strain. To take the pore water pressure into account, a new SPH formulation for soil motion is developed. It is suggested that this equation can be applied to further developments of SPH for saturated soil. As an application of the proposed method, several smoothed particle slope stability analyses and corresponding slope failure simulations are presented, and compared with other solutions. The results show good agreements with other methods in terms of the safety factor and the critical slip surface. As compared with such traditional methods, however, an advantage of SPH is that it can simulate large deformation and post-failure of soil, and can thereby treat a wide range of applications in computational geomechanics, especially those that include large deformation and failure of geomaterials.
Shear strength prediction for reinforced concrete beams without stirrups
Authors: Wei Wei-wei , Che Yi , Gong Jin-xin
Published: June 2011

Traditionally, shear design of concrete beams without stirrups has relied on empirical equations derived from laboratory experiment data. However, such methods lack a sound theoretical basis for shear failure of reinforced concrete (RC) structures due to the complexity of the failure mechanism. In the 1980s, a relatively rational model based on the modified compression field theory (MCFT) was developed at the University of Toronto and subsequently accepted worldwide; it forms the basis of shear provisions in Canadian standards and American specifications for the design of concrete structures. This paper describes further research based on the MCFT. An expression for the average shear stress across a crack was derived and a simplified equation of shear strength considering the size effect in shear was developed. The obtained equations were verified with extensive sets of experimental data from different sources (598 beams in total). It was found that the variation coefficients of the ratio of shear strength calculated using the derived average shear stress across a crack based on the MCFT and the simplified expressions to the test data was small; the mean was about 0·8. It is thus considered that the simplified expressions are suitable for shear analysis and design of RC beams without stirrups.
Non-axis-symmetrical punching shear around internal columns of RC slabs without transverse reinforcement
Authors: Sagaseta Juan , Muttoni Aurelio , Ruiz Miguel Fernández , Tassinari Luca
Published: June 2011

Most analytical approaches and available test data for punching shear in flat slabs assume axis-symmetrical conditions, which seems realistic for representing slabs supported on columns equally spaced in both orthogonal directions. However, in practice, there are many instances where loading, geometry and reinforcement around internal columns differ significantly from ideal axis-symmetrical conditions. Typical examples include slab bridges, flat slabs with unequal spans and footings with unequal widths. This paper presents a series of punching shear tests on slabs without transverse reinforcement and different flexural reinforcement ratios or loading conditions in each orthogonal direction. The tests show that both the type of loading and the amount of flexural reinforcement have a significant influence on the punching shear strength and symmetry of the response. Eurocode 2 and BS 8110 code formulas provided reasonable strength predictions of the tests using the recommended average reinforcement ratio between the x and y directions. A physical explanation behind this assumption is presented, based on critical shear crack theory. A rational analytical approach was developed for non-axis-symmetrical punching, which provides accurate predictions of strength and deformation capacity. The novelty of the proposed method is that it considers a non-uniform shear strength distribution per unit length along the control perimeter, which results in a redistribution of shear near failure.
Shear transfer in lightweight concrete
Authors: Emiko Lim , Thamaraikkannan Vinayagam , Huan Wee Tiong , Thangayah Tamilselvan
Published: June 2011

This research studied the shear transfer in lightweight aggregate concrete and foam concrete. Fourteen series of pre-cracked push-off specimens, made with different concrete strengths were tested. The effects of concrete strength and shear reinforcement parameters on shear transfer behaviour, including shear transfer strength, were analysed. Almost all the specimens failed as a result of slippage along the shear plane. Together with experimental results obtained from a literature review, general formulas for shear transfer strength for reinforced lightweight concrete are also proposed.
‘Exact' theoretical plane-stress yield-line analysis of shear in ‘ordinary' beams
Authors: Gurley C.
Published: June 2011

This paper is part of an effort to re-address upper-bound, especially ‘exact', yield-line analysis of structural concrete in plane stress. The area of ‘ordinary' reinforced beams is a small but ubiquitous part of the total problem area of concrete in plane stress.
Site selection of raingauges using entropy methodologies
Authors: Karimi-Hosseini Azadeh , Bozorg Haddad Omid , Mariño Miguel A.
Published: June 2011

Data on precipitation – one of the important processes of the hydrological cycle – are necessary in water projects. Recognition of precipitation characteristics is necessary in dealing with flood control, plant water requirements, drainage systems design, and so on. Rainfall network design, defined as the proper density and distribution of raingauges in a region's rainfall network, is thus a necessary step toward the success of water projects and regional programming by effective use of data. Monitoring network design involves determining an adequate number and location of stations and providing design criteria for the stations, which may be different even for the same network. In this paper, the location of new rainfall stations in the Gav-Khuni basin rainfall network is determined using the concept of entropy with different criteria. For raingauge site selection, both sequential and genetic algorithms (SAs and GAs) are used. Maximisation of minimum entropy and maximisation of mean entropy objectives are defined for each algorithm. From these results, some stations can be nominated for installation by considering different criteria (e.g. economic, efficiency, precision) and other goals in the management of a watershed. The results indicate better performance and relative primacy of the GA in both objectives of minimum entropy and mean entropy maximisation compared with those obtained by the SA. Moreover, the results show that the nominated optimisation algorithm (GA) significantly improves the minimum and the average of the transinformation entropy, which indirectly influence an increase in the precision of rainfall sampling.
Optimal design of water networks using fuzzy genetic algorithm
Authors: Amirabdollahian Mahsa , Chamani Mohammad Reza , Asghari Keyvan
Published: June 2011

A fuzzy genetic algorithm (FGA) is used to obtain the least-cost design of looped water distribution networks (WDNs). The FGA is a GA-based search method in which fitness evaluation is carried out using a fuzzy decision system (FDS). Unlike previous fuzzy water network optimisation techniques in which different properties were introduced by fuzzy membership functions and the decisions were made by the means of crisp logic, a fully FDS is used to simulate the tolerance in constraint deviation in network elements. The method is applied to two well-known networks currently appearing in the literature as case studies. For each case, based on network layout and optimisation constraints, a FDS is introduced by determining fuzzy parameters, membership functions and the rule set. The results prove the capability of the FGA method of finding optimum solutions in addition to providing a dynamic algorithm that gives engineers more practical insight into easily applying system uncertainty in the optimisation algorithm.
Study of flow structure and sediment entry to a lateral intake
Authors: Esmaeili Varaki Mahdi , Farhoudi Javad , Walker David
Published: June 2011

This paper reports on a set of laboratory experiments involving a layout that is common in irrigation diversion works. The layout involves a lateral intake channel with a diversion dam, positioned to allow the flow to be controlled and managed. Based on experimental measurements and observations, the effect of diversion angle (ranging from 90 to 120°) on the structure of the approaching flow to the lateral intake and amount of sediment entering the intake was investigated. Velocity fields both upstream of the intake in the main channel and in front of the intake in the sluiceway were measured under various discharge combinations of the river, intake and sluice gate. Analysis of sediment measurements showed that the intake with a diversion angle of 110° had the least amount of sediment entering the intake. Analysis of the streamlines in the main channel showed that the width of the bottom-diverted current in the main channel decreased as the diversion angle increased. Furthermore, analysis of the data showed that the product of the width of the diverted current and the mean shear stress decreased when the diversion angle increased from 90 to 110° before increasing again at 120°.
Water quality with storage in permeable pavement basecourse
Authors: Myers Baden , Beecham Simon , van Leeuwen John A.
Published: June 2011

The harvesting, storage and reuse of stormwater from permeable pavement reservoirs provides an opportunity to alleviate water shortages in urban areas. Reservoirs may be filled with a range of basecourse aggregate materials that provide structural support to the pavement. The materials have the potential to affect the quality of stored water. This research investigated changes in water quality when water was stored in two types of basecourse aggregate. Synthetic stormwater was placed in permeable pavement reservoir models filled with dolomite aggregate or quartzite aggregate or control reservoirs with no aggregate. The influence of residence time was investigated by monitoring stored water quality for up to 144 h. Conductivity and pH increased in both aggregate-filled reservoirs. Total suspended solids and turbidity also increased in the aggregate-filled reservoirs, before falling to levels significantly lower than the control reservoirs. Levels of phosphorous and organic nitrogen were significantly lower in the aggregate-filled reservoirs after 144 h. Total zinc, copper and lead were reduced by 94–99% in the aggregate-filled reservoirs compared with the controls after 144 h storage.
Browning Reaction Kinetics of High Hydrostatic Pressure-Treated Peach Puree during Storage
Authors: Khalil Thamer Abdul Kadir , Al-Zubaidy Mazin Ibrahem , Abdulaziz Omer Fawzi
Published: June 2011

Kinetics of browning color development, described as browning index (BI), of peach puree subjected to high hydrostatic pressure (HHP) treatments (400, 500, and 600 MPa/1 and 3 min) during 6 weeks of storage at 4 and 20°C were investigated. This research was conducted to modify the use of pressure scale instead of temperature scale in calculating the kinetic parameters of BI values in peach puree samples. The increase in BI values followed the zero-order kinetic model. The highest activation energy (Ea) was experienced with HHP treatment (400, 500, and 600 MPa/3 min) of peach puree samples stored at 4°C.
FOXL2 and SOX9 Distinguish the Lineage of the Sex Cord–Stromal Cells in Gonadoblastomas
Authors: Buell-Gutbrod Rebecca , Ivanovic Marina , Montag Anthony , Lengyel Ernst , Fadare Oluwole , Gwin Katja
Published: June 2011

Gonadoblastomas are mixed germ cell sex cord–stromal tumors that arise in dysgenetic gonads and are composed of immature germ cells and sex cord–stromal cells of indeterminate differentiation. FOXL2 is one of the first genes expressed in female gonad development, and it is required for proper granulosa cell differentiation during folliculogenesis. SOX9,adownstream target of SRY, the gene in the Y chromosomal sex-determining region, is required for testicular development and for the formation and maintenance of (pre-)Sertoli cells. This study characterized the sex cord–stromal cells of gonadoblastoma by evaluating the expression of these counteracting transcription factors. Archival paraffin-embedded material of 7 gonadoblastomas, 5 of which were overgrown by dysgerminoma, was examined by immunohistochemistry for expression and localization of FOXL2 and SOX9. The sex cord–stromal cells revealed strong nuclear staining for FOXL2 and were negative for SOX9 expression. Germ cells in the gonadoblastoma and dysgerminoma components showed no FOXL2 and SOX9 expression. Areas of transition between gonadoblastoma and dysgerminoma revealed nests with a gradual reduction of FOXL2 expression. Our results support the hypothesis that the sex cord–stromal cell component of gonadoblastomas is of granulosa cell origin. In addition, FOXL2 appears to be a useful marker for the evaluation of overgrowth by dysgerminomas and for the identification of the transition zone of “dysgerminoma in situ.” As FOXL2 and SOX9 are differentially expressed, they also should be useful for distinguishing gonadoblastomas from intratubular germ cell neoplasias and can help to differentiate those with a Sertoli cell component from gonadoblastoma with a granulosa cell component.
Distribution in SAR palaeodoses due to spatial heterogeniety of natural beta dose
Authors: Chauhan Naveen , Singhvi Ashok
Published: June 2011

In luminescence dating of sediments, Mayya et al. (2006) pointed out that at single grain level, the beta dose for quartz grains is heterogeneous. This heterogeneity arises due the fact that the total potassium in sediment is contributed by few feldspar grains with up to 11–14% stoichiometric potassium (Huntley and Baril, 1997). Beta particles have a range of ∼2 mm, which is comparable to grain sizes and inter-grain distances. This fact implies that the spatial fluctuation of beta emitters (K-feldspars) around individual quartz grains results in heterogeneous dose deposition. These fluctuations therefore, lead to an inherent spread in palaeodoses received by individual quartz grains.

In this study, we compute the spread in single aliquot palaeodoses that arises exclusively due to heterogeneity in beta radiation dose received by individual grains. We thus postulate that ‘single aliquots’ (comprising several — typically 100 — heterogeneously irradiated single grains) would have an inherent spread in the palaeodose. In this work, we used Monte Carlo simulations to quantify the extent of spread in palaeodoses arising due to heterogeneity of beta dose and hence put a limit on the precision of age estimation. Simulations results indicated, that, 1) the average of the single aliquot palaeodoses provides the closest approximation to the true palaeodose, 2) the minimum number of aliquots that are needed to obtain a robust estimate of average palaeodose value depend upon desired precision and the concentration of K, and 3) the ratio of maximum to minimum single aliquot palaeodose values for a given K concentration provides a measure of inherent spread arising due to beta dose heterogeneity. Any spread over and above this range, can be ascribed to other sources such as heterogeneous bleaching and sensitivity changes. Radiation dose from other uniformly distributed sources of beta particles (U, Th and Rb) however would reduce this spread.
Changes in natural OSL sensitivity during single aliquot regeneration procedure and their implications for equivalent dose determination
Authors: Singhvi Ashok , Stokes Stephen , Chauhan Naveen , Nagar Yogesh , Jaiswal Manoj
Published: June 2011

Measurement of low temperature (90°C–120°C) Thermoluminescence (TL) sensitivity of natural quartz samples subjected to pre-heating and optical stimulation indicate that significant sensitivity changes can occur during measurement of the natural Optically Stimulated Luminescence (OSL). During the measurement of natural signal, the luminescence sensitivity of samples can change by 40%. The sensitivity changes both during the initial preheat and the measurement of natural OSL. The currently used version of Single Aliquot Regeneration (SAR) protocol measures and corrects for the sensitivity changes after preheat and readout of natural OSL. However, it does not take into account the changes in sensitivity during the readout of the natural signal.

We therefore developed a correction procedure so that both the natural and the regenerated OSL intensities can be measured and plotted with the same sensitivity and suggest that in the absence of such a correction, a considerable fraction of the SAR based ages could have systematic errors. The correction for the sensitivity is based on the use of sensitivity of 110°C TL quartz peak, which is correlated to OSL signal (Murray and Roberts, 1998). The use of 110°C peak provides a reasonable measure of the changes in OSL sensitivity of quartz. A modified Natural Sensitivity Corrected-SAR (NSC-SAR) procedure, that comprises the measurement of, 1) the TL intensity of 110°C peak for a test dose on sample as received (i.e. natural sample) and, 2) the sensitivity of the 110°C peak of the same sample after the preheat and read out of the natural OSL, is proposed. This ratio, termed as Natural Correction Factor (NCF), then provides a way to correct for sensitivity changes. Results on samples from diverse depositional environments indicated that the NSC-SAR consistently (without exception) provided improved distribution in paleodoses i.e. a lower scatter compared to the standard SAR protocol. In addition, the use of this protocol also resolved anomalous cases where the intensity of natural OSL was significantly above the saturation intensity of the regenerated OSL. Implicitly, this study implies a caution on the use of palaeodoses obtained from single grains as such a correction is not possible in the currently used automated single grain OSL measurement systems. The only way now on will be to analyze aliquots with only a grain on them.
Surface dating by luminescence: An overview
Authors: Liritzis Ioannis
Published: June 2011

Daylight radiation resets luminescence ‘clock’ to zero on rock surfaces, but transmission depends on the transparency of the rock. On burial, surfaces are no longer exposed to daylight and accumulation of trapped electrons takes place till the excavation. This reduction of luminescence as a function of depth fulfils the prerequisite criterion of daylight bleaching. Thus rock artefacts and monuments follow similar bleaching rationale as those for sediments. In limestone and marble, daylight can reach depths of 0.5–1 mm and up to 16 mm respectively, while for other igneous rocks e.g. quartz in granites, partial bleaching occurs up to 5mm depth under several hours of daylight exposures and almost complete beaching is achieved in the first 1 mm within about 1 min daylight exposure. The ‘quartz technique’ for limestone monuments containing traces of quartz enables their dating with Optically Stimulated Luminescence (OSL) techniques. The surface luminescence (thermoluminescence, TL or OSL) dating has been developed and further refined on various aspects of equivalent dose determination, complex radiation geometry, incomplete bleaching etc. A historical review of the development including important applications, along with some methodological aspects are discussed.
Potential geoarchaeological sites for luminescence dating in the Ganga Bhagirathi-Hugli delta, west Bengal, India
Authors: Rajaguru Sharad , Deotare Bhaskar , Gangopadhyay Kaushik , Sain Malay , Panja Sheena
Published: June 2011

Archaeological studies in the upper and lower part of the Ganga-Bhaghrathi-Hugli delta were taken up to understand the nature of site formation and human adaptation in a dynamic fluvial zone. This aspect has been neglected in Indian archaeology. However archaeological dating using typological information, has an error margin of a couple of centuries and hence, is of limited use. We suggest that high resolution chronology using Optically Stimulated Luminescence (OSL) and radiocarbon dating can be quite effective in the study of archaeology and human environment relationship in the Ganga-Brahmaputra Delta (GBD).
Trans sodium crocetinate: functional neuroimaging studies in a hypoxic brain tumor
Authors: Sheehan Jason P. , Popp Britney , Monteith Stephen , Toulmin Sushila , Tomlinson Jennifer , Martin Jessica , Cifarelli Christopher P. , Lee Dae-Hee , Park Deric M.
Published: June 2011

Object

Intratumoral hypoxia is believed to be exhibited in high-grade gliomas. Trans sodium crocetinate (TSC) has been shown to increase oxygen diffusion to hypoxic tissues. In this research, the authors use oxygen-sensitive PET studies to evaluate the extent of hypoxia in vivo in a glioblastoma model and the effect of TSC on the baseline oxygenation of the tumor.

Methods

The C6 glioma cells were stereotactically implanted in the right frontal region of rat brains. Formation of intracranial tumors was confirmed on MR imaging. Animals were injected with Copper(II) diacetyl-di(N4-methylthiosemicarbazone) (Cu-ATSM) and then either TSC or saline (6 rats each). Positron emission tomography imaging was performed, and relative uptake values were computed to determine oxygenation within the tumor and normal brain parenchyma. Additionally, TSC or saline was infused into the animals, and carbonic anhydrase 9 (CA9) and hypoxia-inducing factor–1α (HIF-1α) protein expression were measured 1 day afterward.

Results

On PET imaging, all glioblastoma tumors demonstrated a statistically significant decrease in uptake of Cu-ATSM compared with the contralateral cerebral hemisphere (p = 0.000002). The mean relative uptake value of the tumor was 3900 (range 2203–6836), and that of the contralateral brain tissue was 1017 (range 488–2304).

The mean relative hypoxic tumor volume for the saline group and TSC group (6 rats each) was 1.01 ± 0.063 and 0.69 ± 0.062, respectively (mean ± SEM, p = 0.002). Infusion of TSC resulted in a 31% decrease in hypoxic volume. Immunoblot analysis revealed expression of HIF-1α and CA9 in all tumor specimens.

Conclusions

Some glioblastomas exhibit hypoxia that is demonstrable on oxygen-specific PET imaging. It appears that TSC lessens intratumoral hypoxia on functional imaging. Further studies should explore relative hypoxia in glioblastoma and the potential therapeutic gains that can be achieved by lessening hypoxia during delivery of adjuvant treatment.
Temporizing treatment of hyperacute subdural hemorrhage by subdural evacuation port system placement
Authors: Flint Alexander C. , Gean Alisa D. , Manley Geoffrey T. , Rao Vivek A. , Sheridan William F. , von Koch Cornelia S.
Published: June 2011

An acute subdural hematoma (SDH) requiring surgical intervention is treated with craniotomy or craniectomy, in part because it is generally accepted that coagulated blood present in the acute phase cannot be adequately evacuated by less-invasive means such as bur hole drainage. However, a hyperacute SDH in the first few hours after trauma can have mixed-density components on CT scans that are thought to represent subdural blood that is not yet fully coagulated.

The authors report a case in which a hyperacute SDH in a patient receiving antiplatelet therapy was treated with the novel technique of temporizing subdural evacuation port system (SEPS) placement. Placement of an SEPS in the intensive care unit allowed for rapid surgical treatment of the patient's elevated intracranial pressure (ICP) by drainage of 70 ml of fresh subdural blood. After initial SEPS-induced stabilization, the patient underwent operative treatment of the SDH by craniotomy. The combined approach of emergency SEPS placement followed by craniotomy resulted in a dramatic recovery, with improvement from coma and extensor posturing to a normal status on neurological evaluation 5 weeks later. In appropriately selected cases, patients with a hyperacute SDH may benefit from SEPS placement to quickly treat elevated ICP, as a bridge to definitive surgical treatment by craniotomy.
Proteomic identification of glutamine synthetase as a differential marker for oligodendrogliomas and astrocytomas
Authors: Zhuang Zhengping , Qi Meng , Li Jie , Okamoto Hiroaki , Xu David S. , Iyer Rajiv R. , Lu Jie , Yang Chunzhang , Weil Robert J. , Vortmeyer Alexander , Lonser Russell R.
Published: June 2011

Object

Astrocytomas and oligodendrogliomas are primary CNS tumors that remain a challenge to differentiate histologically because of their morphological variability and because there is a lack of reliable differential diagnostic markers. To identify proteins that are differentially expressed between astrocytomas and oligodendrogliomas, the authors analyzed the proteomic expression patterns and identified uniquely expressed proteins in these neoplasms.

Methods

Proteomes of astrocytomas and oligodendrogliomas were analyzed using 2D gel electrophoresis and subsequent computerized gel analysis to detect differentially expressed proteins. The proteins were identified using high-performance liquid chromatography accompanied by tandem mass spectrometry. To determine the role of the differentially expressed proteins in astrocytes, undifferentiated glial cell cultures were treated with dibutyryl–cyclic adenosine monophosphate (cAMP).

Results

Two-dimensional gel electrophoresis revealed that glutamine synthetase was differentially expressed in astrocytomas and oligodendrogliomas. Western blot and immunohistochemical analyses confirmed the increased expression of glutamine synthetase in astrocytomas compared with oligodendrogliomas. Whereas glutamine synthetase expression was demonstrated across all grades of astrocytomas (Grade II–IV [15 tumors]) and oligoastrocytomas (4 tumors), it was expressed in only 1 oligodendroglioma (6% [16 tumors]). Treatment of undifferentiated glial cell cultures with dibutyryl-cAMP resulted in astrocyte differentiation that was associated with increased levels of glial fibrillary acidic protein and glutamine synthetase.

Conclusions

These data indicate that glutamine synthetase expression can be used to distinguish astrocytic from oligodendroglial tumors and may play a role in the pathogenesis of astrocytomas.
Effect of deep wound infection following lumbar arthrodesis for degenerative disc disease on long-term outcome: a prospective study
Authors: Falavigna Asdrubal , Righesso Orlando , Traynelis Vincent C. , Teles Alisson Roberto , Silva Pedro Guarise da
Published: June 2011

Object

Deep wound infections are one of the most common and serious complications of spinal surgery. The impact of such infections on long-term outcomes is not well understood. The purpose of this study was to evaluate the functional status and satisfaction in patients who suffered a deep wound infection after undergoing lumbar arthrodesis for symptomatic degenerative disc disease.

Methods

The authors conducted a prospective study in 13 patients with a clinical and radiological diagnosis of symptomatic degenerative lumbar stenosis and instability; after undergoing decompression and instrumentation-augmented arthrodesis, the patients suffered a deep wound infection (infection group). A 3:1 (39-patient) matched cohort was selected for comparison (control group). All surgeries were performed during the same period and by a single surgeon. The postoperative infections were all treated in a similar manner and the instrumentation was not removed. Both groups were followed up and assessed with validated outcome instruments: Numerical Rating Scale of pain, Oswestry Disability Index, 36-Item Short Form Health Survey, Beck Depression Inventory, and Hospital Anxiety and Depression Scale. Patient satisfaction was also determined.

Results

The median follow-up duration was 22 months (range 6–108 months). The mean patient age was 62 ± 10 years, and 59.6% of the patients were female. There was no significant difference between the groups in pain, functional disability, quality of life, or depression and anxiety. However, 53.8% of the patients with infection were not satisfied with the procedure at the final evaluation, compared with 15.4% of the patients without a deep wound infection (p = 0.003).

Conclusions

Patients with successfully treated postoperative deep wound infections do not have a difference in functional outcome compared with patients who underwent an identical operation but did not suffer a complicating infection. Patients who suffered an infection were more likely to be unsatisfied with the procedure than patients who did not.
Rarity as a life‐history correlate inDudleya(Crassulaceae)
Authors: Dorsey Ann E. , Wilson Paul
Published: June 2011

•Premise of the study: Differences in rarity among species can be caused by adaptation to local conditions along with correlated evolution in characters that limit geographic range size. For this kind of divergence, the resulting species differ in their ability to thrive in varying environments. Because rare species are more prone to extinction than widespread species, trade‐offs in life history predispose the resulting lineages to clade selection.

•Methods: NineDudleyaspecies live in the Santa Monica Mountains: five neoendemics, one species intermediate in rarity, and three with broader ranges. Life‐history traits were correlated against one another. To understand habitat dependence, the species were grown in an inland garden and in a coastal garden, and the disparity in growth and reproduction in the two gardens was compared among species.

•Key results: Rare species reproduced earlier and grew to be smaller than common species. The small body size of the rare species was correlated with small reproductive outputs compared with those of the large‐bodied common species. The growth disparity between plants in the two gardens was greatest for the rare species. The rare species had a lower tolerance for hot, dry conditions compared with the common species. In the Santa Monica Mountains, the habitat conditions required by the rare species are not as prevalent as those of the common species.

•Conclusions: The data are consistent with the view that differences in life histories constrained by trade‐offs affect range size. Such differences in rarity become the grist for clade selection at the scale of macroevolution.
Enhancing pollen competition by delaying stigma receptivity: Pollen deposition schedules affect siring ability, paternal diversity, and seed production inCollinsia heterophylla(Plantaginaceae)
Authors: Lankinen Åsa , Madjidian Josefin A.
Published: June 2011

•Premise of the study:Even though pollen deposition schedules may have profound effects on the evolutionary outcome of pollen competition, few studies have investigated such effects in relation to pistil traits such as delayed stigma receptivity that enhance pollen competition. InCollinsia heterophylla, a largely outcrossing species with delayed stigma receptivity, we performed a series of controlled crosses involving several donors to understand how timing of pollen deposition influences siring ability, paternal diversity, and offspring fitness.

•Methods:Pollen was applied to fully receptive stigmas either as mixtures or consecutively with or without a time lag to mimic cases with early or delayed stigma receptivity. We used a genetic marker to assess offspring paternity.

•Key results:As expected, siring ability was affected by application order in crosses without a time lag, providing a first‐donor advantage for pollen arriving on unreceptive stigmas. However, because pollen donor identity influenced siring ability, delaying stigma receptivity may still favor pollen of high competitive ability. In crosses on fully receptive pistils with a time lag of 24 h, a surprisingly high proportion of seeds (12–47%) were sired by pollen applied last. A novel finding was that pollen applied only once (as a mixture), mimicking delayed stigma receptivity, led to higher paternal diversity within progeny families, which was associated with increased seed production.

•Conclusions:Our results suggest fitness advantages of enhancing pollen competition by delaying stigma receptivity inC. heterophylla, particularly in relation to increased paternal diversity.
Isolation and characterization of microsatellite loci from apomictic Hypericum perforatum (Hypericaceae)
Authors: Corral Jose M. , Molins Marta Puente , Aliyu Olawale M. , Sharbel Timothy F.
Published: June 2011

• Premise of the study: Microsatellite markers were developed to study the origins and evolution of apomictic Hypericum perforatum, a polyploid invasive perennial herb indigenous to Europe that produces compounds of medicinal/pharmaceutical importance.

• Methods and Results: Eleven primer sets were developed using a non‐radioactive protocol. All loci were polymorphic, showing from 2 to 9 alleles per locus. Observed and expected heterozygosity averaged 0.861 and 0.772, respectively, across four studied populations. Most primers also amplified successfully in eight other Hypericum species.

• Conclusions: Markers developed in this study provide genetic tools for studies of apomixis and invasiveness, both on the intra‐ and interspecific levels.
Isolation and characterization of 10 microsatellite loci from Korean Leontopodium japonicum (Asteraceae)
Authors: Lee Dong‐Hyuk , Lee Jung‐Hyun , Choi Byoung‐Hee
Published: June 2011

• Premise of the study: Microsatellite primers were developed for the alpine plant Leontopodium japonicum to evaluate its population genetics structure as a means for devising future conservation strategies.

• Methods and Results: Ten polymorphic microsatellite markers were developed in Korean populations of L. japonicum. Genetic diversity was analyzed among 38 individuals from two populations. Overall, each locus had 3 to 17 alleles, and their observed and expected heterozygosities ranged from 0.0000 to 0.8750 and from 0.0000 to 0.8929, respectively.

• Conclusions: The microsatellite markers described here are valuable tools for population genetics research of L. japonicum. They can be used to obtain information about suitable management strategies for protecting other related and endangered “edelweiss” species.
Newly developed primers for complete ycf1 amplification in Pinus (Pinaceae) chloroplasts with possible family‐wide utility
Authors: Parks Matthew , Liston Aaron , Cronn Rich
Published: June 2011

• Premise of the study: Primers were designed to amplify the highly variable locus ycf1 from all 11 subsections of Pinus to facilitate plastome assemblies based on short sequence reads as well as future phylogenetic and population genetic analyses.

• Methods and Results: Primer design was based on alignment of 33 Pinus and four Pinaceae plastomes with mostly incomplete ycf1 sequences. Sanger sequencing of 12 Pinus accessions resulted in open reading frames ranging in size from 5.2 to 6.1 kbp. Highest sequence diversity was identified in two regions totaling 5.5 kbp aligned length, which can be targeted in all pine subsections with three primer combinations. Preliminary results suggest the primers described also amplify homologous targets in the broader Pinaceae.

• Conclusions: The successful design and implementation of PCR primers spanning the large, variable locus ycf1 in Pinus represents the development of a valuable tool in pine genetic studies, and should facilitate studies throughout Pinaceae.
The Course of Esophageal Varices in Patients with Hepatitis C Cirrhosis Responding to Interferon/ Ribavirin Therapy
Authors: D'Ambrosio Roberta , Aghemo Alessio , Rumi Maria Grazia , Primignani Massimo , Dell'Era Alessandra , Lampertico Pietro , Donato Maria Francesca , De Nicola Stella , Prati Gian Maria , de Franchis Roberto , Colombo Massimo
Published: June 2011

Background

Gastrointestinal haemorrhage from ruptured esophageal varices (EV) is a significant cause of morbidity and mortality in patients with HCV-related cirrhosis. The risk of developing EV and bleeding is influenced by hepatitis severity, which can be attenuated by successful interferon (IFN) therapy. Our aim was to prospectively assess whether a successful IFN therapy modifies development and/or progression of EV in patients with HCV-related compensated cirrhosis.

Methods

Child–Pugh A patients with either no or small (F1) EV underwent surveillance with repeated endoscopy during and after completion of IFN-based therapy.

Results

A total of 127 patients (59 years, 79 males, 65 HCV-1/4 and 17 F1 EV) received weight-based ribavirin (RBV) combined with either IFN-α2b 3 MU three times per week ( n=36), weekly pegylated (PEG)-IFN-α2b 1.5 μg/kg ( n=68) or weekly PEG-IFN-α2a 180 μg ( n=23). Patients were followed-up for 18–108 months after treatment completion with a median endoscopic follow-up of 68 months for the 62 patients with a sustained virological response (SVR) and 57 months for the 65 non-SVR patients ( P=0.3). De novo EV developed in 10 (9.1%) patients including 2/57 SVR and 8/53 non-SVR (3.5% versus 15.1%; P=0.047), whereas EV progressed in size in 3 patients, including 1/5 SVR and 2/12 non-SVR ( P=0.87). Two non-SVR patients bled from EV and one died.

Conclusions

A successful IFN therapy prevents or delays the de novo onset of EV in patients with compensated cirrhosis due to HCV, but does not abrogate the need for continued endoscopic surveillance.
Late-age Onset Systemic Sclerosis
Authors: MANNO REBECCA L. , WIGLEY FREDRICK M. , GELBER ALLAN C. , HUMMERS LAURA K.
Published: June 2011

Objective.

Although patients who develop systemic sclerosis (SSc) later in life (≥ 65 yrs) may express the entire clinical spectrum of disease, we hypothesize that patients with late-age onset SSc incur a different risk for specific organ manifestations of disease compared to those with early-age onset SSc.

Methods.

In total, 2300 patients with SSc were evaluated between 1990 and 2009 and reviewed from a university-based scleroderma center cohort. Demographic profile, SSc subtype, autoantibody status, Medsger severity scores, pulmonary function tests, echocardiography, and right heart catheterization measures were compared between late-age onset vs younger-age onset patients with SSc.

Results.

Overall, 2084 patients (91%) developed SSc prior to age 65, while 216 (9%) were ≥ 65 years. Late-age onset patients had a significantly higher proportion of anticentromere antibodies (42% vs 27%; p = 0.001) compared to early-age onset patients. Risk of pulmonary hypertension (OR 1.76, 95% CI 1.00, 3.12), muscle weakness (OR 1.85, 95% CI 1.30, 1.64), renal impairment (OR 2.83, 95% CI 1.98, 4.04), and cardiac disease (OR 2.69, 95% CI 1.92, 3.78) was greater among those with late-age onset SSc; although risk of digital ischemia (OR 0.64, 95% CI 0.47, 0.86) was reduced. The cumulative incidence of pulmonary hypertension at 5 years was greater among those with late-age onset SSc (9%) compared to those with early-age onset SSc (2.7%; log-rank, p < 0.001).

Conclusion.

These findings suggest that older patients with SSc are at greater risk for pulmonary hypertension, renal impairment, cardiac disease, and muscle weakness. Awareness of the distinct risk for specific organ manifestations in SSc, in particular pulmonary hypertension, should guide the care of patients with SSc whose disease begins after age 65.