bluuebunny/crossref_metadata_2025 huggingface dataset:
Congenital Heart Disease in Mexico
Authors: Calderón-Colmenero Juan , Cervantes-Salazar Jorge , Curi-Curi Pedro , Ramírez-Marroquín Samuel
Published: March 2013

Consistent with the mission of the World Society for Pediatric and Congenital Heart Surgery to promote health care for children with congenital heart disease all around the world, a Mexican Association of Specialists in Congenital Heart Disease (abbreviated in Spanish as AMECC) was created in Mexico in 2008. Our efforts were coordinated with those of the National Health Secretary with the objective being implementation of a national plan for regionalization of care for patients with congenital heart disease. To improve our knowledge related to technologic and human resources for management of congenital heart disease, we developed a national survey. Finally, a national database was created for collecting all Mexican centers’ information related to congenital heart disease care in order to quantify the advances related to the proposed plans. The database utilized international consensus nomenclature. The aim of this article is to show the sequence of our actions in relation to direct accomplishments and the current status of congenital heart disease care in Mexico. This article emphasizes the main aspects of these actions: regionalization project implementation, national survey results, and cardiovascular pediatric surgical database creation. Knowledge of outcomes related to successful actions would be useful for those countries that face similar challenges and may lead them to consider adoption of similar measures with the respective adjustments to their own reality.
Can We Blame the Climate of an Organization for the Stress Experienced by Employees?
Authors: Sahni Sanjeev P. , Kumar Vaijayanthee
Published: March 2013

The environment of workplace has received much attention in research in human resource literature. However, its impact on employee’s behavior such as stress has not been established widely. This research explores the relationship between stress and organizational climate among employees of a large manufacturing organization. A sample of 625 employees was selected using convenience sampling method to measure the level of occupational stress and organizational climate. Pearson’s correlation coefficient was computed to study the relationship between the two variables. To identify the predictors of occupational stress with organizational climate as a criterion, stepwise regression analysis was calculated. The findings indicate that there exists a negative significant correlation between the two variables under study. Regression analysis reveals that support system, decision-making, motivational level, and warmth as climate factors, significantly predict occupational stress. The findings are significant for management practitioners, organizational psychologists, and human resources personnel since it empirically directs them to focus on diagnosing the climate of the organization, especially giving importance to strengthen the support system and empowering employees with decision-making power which, if neglected, may cause stress to employees.
Factors Affecting Purchase Intention on 3G Value-added Services
Authors: Du Huiying , Zhu Ge , Lv Tingjie , Sun Xuan
Published: March 2013

This article provides insights into consumer behavior, and the results have important implications for designers, managers, marketers, and system providers of 3G value-added services to explore a conceptual model for analyzing customers’ perceptions of using 3G value-added services. An empirical investigation was carried out to test the hypotheses. The samples include 826 professional participants. Structural equation modeling (SEM) is used to test the relationships of the model. After reviewing the previous research papers, a conceptual model of customer adoption is developed and nine important factors are proposed, namely, perceived usefulness, perceived ease of use, perceived security, perceived price, use experience, perceived enjoyment, need for uniqueness, social influence, context and compatibility. Then a big sample of questionnaire investigation in Chinese 3G value-added service market is conducted. The empirical findings are as follows: (a) security and social influence are two of the most important factors in 3G market; (b) 3G value-added services must be enjoyable and useful; (c) using context should be friendly and compatible. The results not only help to develop a sophisticated understanding of 3G adoption theories for researchers but also offer useful knowledge to those involved in promoting 3G value-added services to potential purchasers.
Exome sequencing identifies titin mutations causing hereditary myopathy with early respiratory failure (HMERF) in families of diverse ethnic origins
Authors: Toro Camilo , Olivé Montse , Dalakas Marinos C , Sivakumar Kumaraswami , Bilbao Juan M , Tyndel Felix , Vidal Noemí , Farrero Eva , Sambuughin Nyamkhishig , Goldfarb Lev G
Published: March 2013

Background

Hereditary myopathy with early respiratory failure (HMERF) was described in several North European families and recently linked to a titin gene (TTN) mutation. We independently studied HMERF-like diseases with the purpose to identify the cause, refine diagnostic criteria, and estimate the frequency of this disease among myopathy patients of various ethnic origins.

Methods

Whole exome sequencing analysis was carried out in a large U.S. family that included seven members suffering from skeletal muscle weakness and respiratory failure. Subsequent mutation screening was performed in further 45 unrelated probands with similar phenotypes. Studies included muscle strength evaluation, nerve conduction studies and concentric needle EMG, respiratory function test, cardiologic examination, and muscle biopsy.

Results

A novel TTN p.Gly30150Asp mutation was identified in the highly conserved A-band of titin that co-segregated with the disease in the U.S. family. Screening of 45 probands initially diagnosed as myofibrillar myopathy (MFM) but excluded based on molecular screening for the known MFM genes led to the identification of a previously reported TTN p.Cys30071Arg mutation in one patient. This same mutation was also identified in a patient with suspected HMERF. The p.Gly30150Asp and p.Cys30071Arg mutations are localized to a side chain of fibronectin type III element A150 of the 10th C-zone super-repeat of titin.

Conclusions

Missense mutations in TTN are the cause of HMERF in families of diverse origins. A comparison of phenotypic features of HMERF caused by the three known TTN mutations in various populations allowed to emphasize distinct clinical/pathological features that can serve as the basis for diagnosis. The newly identified p.Gly30150Asp and the p.Cys30071Arg mutation are localized to a side chain of fibronectin type III element A150 of the 10th C-zone super-repeat of titin.
A word of caution: do not wake sleeping dogs; micrometastases of melanoma suddenly grew after progesterone treatment
Authors: Mordoh Jose , Tapia Ivana Jaqueline , Barrio Maria Marcela
Published: March 2013

Background

Hormonal treatment might affect the immune response to tumor antigens induced in cancer patients who are being vaccinated.

Case presentation

A 33 years-old woman was diagnosed with cutaneous melanoma in May 2009. Her melanoma was located in the intermammary sulcus, had a Breslow thickness of 4 mm, a Clark’s level IV, it was ulcerated and highly melanotic. The bilateral sentinel node biopsy was negative. She entered into a randomized Phase II/III clinical study comparing a vaccine composed of irradiated melanoma cells plus BCG plus GM-CSF versus IFN-alpha 2b and she was assigned to the vaccine arm. During the two years treatment she remained disease-free; the final CAT scan being performed in August 2011. Between November and December 2011, her gynecologist treated her with three cycles of 200 mg progesterone/day for ten days, every two weeks, for ovary dysfunction. In November 2011 the patient returned to the Hospital for clinical and imaging evaluation and no evidence of disease was found. At the next visit in March 2012 an ultrasound revealed multiple, large metastases in the liver. A CAT scan confirmed the presence of liver, adrenal glands and spleen metastases. A needle biopsy of a liver lesion revealed metastatic melanoma of similar characteristics to the original tumor. We suggest that progesterone treatment triggered proliferation of so far dormant micrometastases that were controlled during CSF470 vaccine treatment.

Conclusion

The use of progesterone in patients with melanoma that are under immunological treatments should be carefully considered, since progesterone could modify the balance of pro-inflammatory and Th1 functions to a regulatory and anti-inflammatory profile of the immune system that could have an impact in tumor progression.
The relationship between visceral fat thickness and bone mineral density in sedentary obese children and adolescents
Authors: Júnior Ismael Forte Freitas , Cardoso Jefferson Rosa , Christofaro Diego G Destro , Codogno Jamile Sanches , de Moraes Augusto César Ferreira , Fernandes Rômulo Araújo
Published: March 2013

Background

Among adults, obesity has been positively related to bone mineral density. However, recent findings have pointed out that abdominal obesity could be negatively related to bone density. The above mentioned relationship is not clear among pediatric populations. Therefore, this cross-sectional study analyzed the relationship between thickness of abdominal adipose tissue and bone mineral variables in sedentary obese children and adolescents.

Methods

One hundred and seventy five obese children and adolescents (83 male and 92 female) with ages ranging from 6 to 16 years-old were analyzed. Bone mineral content and density were estimated by dual-energy X-ray absorptiometry and ultrasound equipment which estimated the thickness of the abdominal adipose tissue. Pubertal stage was self-reported by the participants.

Results

The mean age was 11.1 (SD = 2.6). Thickness of the abdominal adipose tissue was negatively related to bone mineral density (r = −0.17 [r
95%CI: -0.03;-0.32]), independent of gender, pubertal stage and other confounders (β = −0.134 ± 0.042 [β95%CI: -0.217; -0.050]).

Conclusions

In sedentary obese children and adolescents abdominal obesity is negatively related to bone mineral density, suggesting a potential link between abdominal obesity and osteoporosis.
Screening NK-, B- and T-cell phenotype and function in patients suffering from Chronic Fatigue Syndrome
Authors: Curriu Marta , Carrillo Jorge , Massanella Marta , Rigau Josepa , Alegre José , Puig Jordi , Garcia-Quintana Ana M , Castro-Marrero Jesus , Negredo Eugènia , Clotet Bonaventura , Cabrera Cecilia , Blanco Julià
Published: March 2013

Background

Chronic Fatigue Syndrome (CFS) is a debilitating neuro-immune disorder of unknown etiology diagnosed by an array of clinical manifestations. Although several immunological abnormalities have been described in CFS, their heterogeneity has limited diagnostic applicability.

Methods

Immunological features of CFS were screened in 22 CFS diagnosed individuals fulfilling Fukuda criteria and 30 control healthy individuals. Peripheral blood T, B and NK cell function and phenotype were analyzed by flow cytometry in both groups.

Results

CFS diagnosed individuals showed similar absolute numbers of T, B and NK cells, with minor differences in the percentage of CD4+ and CD8+ T cells. B cells showed similar subset frequencies and proliferative responses between groups. Conversely, significant differences were observed in T cell subsets. CFS individuals showed increased levels of T regulatory cells (CD25+/FOXP3+) CD4 T cells, and lower proliferative responses in vitro and in vivo. Moreover, CD8 T cells from the CFS group showed significantly lower activation and frequency of effector memory cells. No clear signs of T-cell immunosenescence were observed. NK cells from CFS individuals displayed higher expression of NKp46 and CD69 but lower expression of CD25 in all NK subsets defined. Overall, T cell and NK cell features clearly clustered CFS individuals.

Conclusions

Our findings suggest that alterations in T-cell phenotype and proliferative response along with the specific signature of NK cell phenotype may be useful to identify CFS individuals. The striking down modulation of T cell mediated immunity may help to understand intercurrent viral infections in CFS.
A hybrid multi-path routing algorithm for industrial wireless mesh networks
Authors: Zuo Yun , Ling Zhihao , Yuan Yifeng
Published: March 2013

Multi-path routing, a routing technique that enables data transmission over multiple paths, is an effective strategy in achieving reliability in wireless sensor networks. However, multi-path routing does not guarantee deterministic transmission. This is because more than one path is available for transferring data from the source node to the destination node. A hybrid multi-path routing algorithm is proposed for industrial wireless mesh networks for improving reliability and determinacy of data transmission, as well as to effectively deal with link failures. The proposed algorithm adopts the enhanced Dijkstra’s algorithm for searching the shortest route from the gateway to each end node for first route setup. A virtual pheromone distinct from the regular pheromone is introduced to realize pheromone diffusion and updating. In this way, multiple routes are searched based on the ant colony optimization algorithm. The routes used for data transmission are selected based on their regular pheromone values, facilitating the delivery of data through better routes. Link failures are then handled using route maintenance mechanism. Simulation results demonstrate that the proposed algorithm outperforms traditional algorithms in terms of average end-to-end delay, packet delivery ratio, and routing overhead; moreover, it has a strong capacity to cope with topological changes, thereby making it more suitable for industrial wireless mesh networks.
Quantifiable diagnosis of muscular dystrophies and neurogenic atrophies through network analysis
Authors: Sáez Aurora , Rivas Eloy , Montero-Sánchez Adoración , Paradas Carmen , Acha Begoña , Pascual Alberto , Serrano Carmen , Escudero Luis M
Published: March 2013

Background

The diagnosis of neuromuscular diseases is strongly based on the histological characterization of muscle biopsies. However, this morphological analysis is mostly a subjective process and difficult to quantify. We have tested if network science can provide a novel framework to extract useful information from muscle biopsies, developing a novel method that analyzes muscle samples in an objective, automated, fast and precise manner.

Methods

Our database consisted of 102 muscle biopsy images from 70 individuals (including controls, patients with neurogenic atrophies and patients with muscular dystrophies). We used this to develop a new method, Neuromuscular DIseases Computerized Image Analysis (NDICIA), that uses network science analysis to capture the defining signature of muscle biopsy images. NDICIA characterizes muscle tissues by representing each image as a network, with fibers serving as nodes and fiber contacts as links.

Results

After a ‘training’ phase with control and pathological biopsies, NDICIA was able to quantify the degree of pathology of each sample. We validated our method by comparing NDICIA quantification of the severity of muscular dystrophies with a pathologist’s evaluation of the degree of pathology, resulting in a strong correlation (R = 0.900, P <0.00001). Importantly, our approach can be used to quantify new images without the need for prior ‘training’. Therefore, we show that network science analysis captures the useful information contained in muscle biopsies, helping the diagnosis of muscular dystrophies and neurogenic atrophies.

Conclusions

Our novel network analysis approach will serve as a valuable tool for assessing the etiology of muscular dystrophies or neurogenic atrophies, and has the potential to quantify treatment outcomes in preclinical and clinical trials.
Lack of association of rare functional variants in TSC1/TSC2 genes with autism spectrum disorder
Authors: Bahl Samira , Chiang Colby , Beauchamp Roberta L , Neale Benjamin M , Daly Mark J , Gusella James F , Talkowski Michael E , Ramesh Vijaya
Published: March 2013

Background

Autism spectrum disorder (ASD) is reported in 30 to 60% of patients with tuberous sclerosis complex (TSC) but shared genetic mechanisms that exist between TSC-associated ASD and idiopathic ASD have yet to be determined. Through the small G-protein Rheb, the TSC proteins, hamartin and tuberin, negatively regulate mammalian target of rapamycin complex 1 (mTORC1) signaling. It is well established that mTORC1 plays a pivotal role in neuronal translation and connectivity, so dysregulation of mTORC1 signaling could be a common feature in many ASDs. Pam, an E3 ubiquitin ligase, binds to TSC proteins and regulates mTORC1 signaling in the CNS, and the FBXO45-Pam ubiquitin ligase complex plays an essential role in neurodevelopment by regulating synapse formation and growth. Since mounting evidence has established autism as a disorder of the synapses, we tested whether rare genetic variants in TSC1, TSC2, MYCBP2, RHEB and FBXO45, genes that regulate mTORC1 signaling and/or play a role in synapse development and function, contribute to the pathogenesis of idiopathic ASD.

Methods

Exons and splice junctions of TSC1, TSC2, MYCBP2, RHEB and FBXO45 were resequenced for 300 ASD trios from the Simons Simplex Collection (SSC) using a pooled PCR amplification and next-generation sequencing strategy, targeted to the discovery of deleterious coding variation. These detected, potentially functional, variants were confirmed by Sanger sequencing of the individual samples comprising the pools in which they were identified.

Results

We identified a total of 23 missense variants in MYCBP2, TSC1 and TSC2. These variants exhibited a near equal distribution between the proband and parental pools, with no statistical excess in ASD cases (P > 0.05). All proband variants were inherited. No putative deleterious variants were confirmed in RHEB and FBXO45. Three intronic variants, identified as potential splice defects in MYCBP2 did not show aberrant splicing upon RNA assay. Overall, we did not find an over-representation of ASD causal variants in the genes studied to support them as contributors to autism susceptibility.

Conclusions

We did not observe an enrichment of rare functional variants in TSC1 and TSC2 genes in our sample set of 300 trios.
Low-frequency seismic deghosting
Authors: Amundsen Lasse , Zhou Hongbo
Published: March 2013

We evaluated a solution to seismic deghosting that deghosts the low-frequency components of the seismic pressure data. In an approximation that neglected the dependence on wavenumbers, the low-frequency deghosted pressure field was computed trace-by-trace as the sum of the pressure field and its scaled temporally integrated and temporally differentiated fields. We gave simple numerical examples that demonstrated the concept. The method was found to deghost data up to a frequency that is typically half of the second notch frequency. On the low-frequency side, the deghosting method was limited by the signal-to-noise ratio. The low-frequency deghosting technique can be appropriate to apply to the part of seismic data that have penetrated and reflected beneath complex and attenuating overburdens such as basalt, salt, and chalk.
Asymptotics for the First Passage Times of Lévy Processes and Random Walks
Authors: Denisov Denis , Shneer Vsevolod
Published: March 2013

We study the exact asymptotics for the distribution of the first time, τx, a Lévy process Xt crosses a fixed negative level -x. We prove that ℙ{τx >t} ~V(x) ℙ{Xt≥0}/t as t→∞ for a certain function V(x). Using known results for the large deviations of random walks, we obtain asymptotics for ℙ{τx>t} explicitly in both light- and heavy-tailed cases.
Domain of Attraction of the Quasistationary Distribution for Birth-and-Death Processes
Authors: Zhang Hanjun , Zhu Yixia
Published: March 2013

We consider a birth–death process {X(t),t≥0} on the positive integers for which the origin is an absorbing state with birth coefficients λn,n≥0, and death coefficients μn,n≥0. If we define A=∑n=1∞ 1/λnπn and S=∑n=1∞ (1/λnπn)∑i=n+1∞ πi, where {πn,n≥1} are the potential coefficients, it is a well-known fact (see van Doorn (1991)) that if A=∞ and S<∞, then λC>0 and there is precisely one quasistationary distribution, namely, {aj(λC)}, where λC is the decay parameter of {X(t),t≥0} in C={1,2,...} and aj(x)≡μ1-1πjxQj(x), j=1,2,.... In this paper we prove that there is a unique quasistationary distribution that attracts all initial distributions supported in C, if and only if the birth–death process {X(t),t≥0} satisfies bothA=∞ and S<∞. That is, for any probability measure M={mi, i=1,2,...}, we have limt→∞ℙM(X(t)=j∣ T>t)= aj(λC), j=1,2,..., where T=inf{t≥0 : X(t)=0} is the extinction time of {X(t),t≥0} if and only if the birth–death process {X(t),t≥0} satisfies both A=∞ and S<∞.
Computing Stationary Expectations in Level-Dependent QBD Processes
Authors: Baumann Hendrik , Sandmann Werner
Published: March 2013

Stationary expectations corresponding to long-run averages of additive functionals on level-dependent quasi-birth-and-death processes are considered. Special cases include long-run average costs or rewards, moments and cumulants of steady-state queueing network performance measures, and many others. We provide a matrix-analytic scheme for numerically computing such stationary expectations without explicitly computing the stationary distribution of the process, which yields an algorithm that is as quick as its counterparts for stationary distributions but requires far less computer storage. Specific problems arising in the case of infinite state spaces are discussed and the application of the algorithm is demonstrated by a queueing network example.
Conditional Distributions of Processes Related to Fractional Brownian Motion
Authors: Fink Holger , Klüppelberg Claudia , Zähle Martina
Published: March 2013

Conditional distributions for affine Markov processes are at the core of present (defaultable) bond pricing. There is, however, evidence that Markov processes may not be realistic models for short rates. Fractional Brownian motion (FBM) can be introduced by an integral representation with respect to standard Brownian motion. Using a simple prediction formula for the conditional expectation of an FBM and its Gaussianity, we derive the conditional distributions of FBM and related processes. We derive conditional distributions for fractional analogies of prominent affine processes, including important examples like fractional Ornstein–Uhlenbeck or fractional Cox–Ingersoll–Ross processes. As an application, we propose a fractional Vasicek bond market model and compare prices of zero-coupon bonds to those achieved in the classical Vasicek model.
Duality Between the Two-Locus Wright–Fisher Diffusion Model and the Ancestral Process with Recombination
Authors: Mano Shuhei
Published: March 2013

Known results on the moments of the distribution generated by the two-locus Wright–Fisher diffusion model, and the duality between the diffusion process and the ancestral process with recombination are briefly summarized. A numerical method for computing moments using a Markov chain Monte Carlo simulation and a method to compute closed-form expressions of the moments are presented. By applying the duality argument, the properties of the ancestral recombination graph are studied in terms of the moments.
Adsorption of Cellulase Isolated from Aspergillus Niger on Chitosan/Alginate Particles Functionalized with Epichlorohydrin
Authors: Rodrigues Elaine C. , Bezerra Bruna T. C. , Farias Barbara V. , Adriano Wellington S. , Vieira Rodrigo S. , Azevedo Diana C. S. , Silva Ivanildo J.
Published: March 2013

This work investigates the adsorption of cellulase (isolated from Aspergillus niger) in a fixed-bed column using chitosan/alginate particles functionalized with epichlorohydrin (Cs/Ag–E) as the adsorbent. The particles were prepared and characterized with respect to apparent density, particle porosity, particle size, surface chemistry and thermal stability. Cellulase solutions were prepared in sodium citrate buffer (20 mM) at pH 5. Several breakthrough curves were obtained by varying the flow rate and feed concentrations in order to evaluate the suitable bed height and determine the adsorption isotherm, respectively. The adsorption isotherm fitted well with Langmuir equation with maximum adsorption capacity of about 11 mg of cellulase/g of adsorbent. Successive cycles (adsorption/washing/elution) were performed and the results demonstrate the reversibility of the process and its potential for enzyme purification and separation. However, cellulase activity in the eluted fraction is only 29% of that of the fresh enzyme fed to the column.
Wind Energy Potential Investigation and Micrositting in Langkawi Island, Malaysia
Authors: Albani A. , Ibrahim M.Z. , Yong K.H. , Muzathik A.M.
Published: March 2013

The aim of this study was to predict the wind energy potential over the Langkawi Island, Malaysia. The wind data for year 2009 was collected from Malaysia Meteorology Department (MMD) and then extrapolated to the hub heights of various turbines. Wind turbines with rated powers between 1 kW and 110 kW were chosen for annual energy production calculations and best fitted ones were used for the micrositting analysis. In this study, the turbine with 22 kW rated power with hub height 30 m was selected based on its best value of capacity factor. The wind speed frequency per year is highly peaked in the range 1–6 m/s, this indicate that most of the wind speed at Langkawi Island lies in this range. The ‘WAsP’ and ‘WindPRO’ softwares were used for the wind statistics and energy calculations. Calculated energy production of located 10 turbines with total capacity of 0.22 MW was 111.1 MWh. Suitable sites were selected according to the created wind power and energy maps. The future cost of maintenance and the status of area either its reserved or conserved by the government were the factors that be considered for selection of site area.
Betz Limit Not an Exact Optimum
Authors: Farthing S.P.
Published: March 2013

The Betz high speed ratio limit has not been derived in the complete generality that would prove it absolute for an unshrouded actuator. The assumed uniform wake or thrust loading is hard to prove optimal. Many authors also assume uniform flow at the rotor or equivalently the differential form of the momentum equation but neither is necessary in the derivation or in fact true. Calculations of the expanding vortex ring wake have indicated lower velocity at the rotor's edge and slightly higher in the center. It is shown that if the uniform wake is perturbed by a fraction of the same variation function, the Betz power coefficient is raised. The increase is very small for a Hawt but might be bigger for a 2D actuator with a larger variation function. Thus the Betz value is very close to a local optimum, but not exact or absolute.
Wind Turbines in Series; A Parametric Analysis
Authors: Hancock Philip E.
Published: March 2013

An analysis is made of wind turbines in a row by means of an extension to actuator disk theory and a representation of the turbulent diffusion in the wake by a velocity deficit scale and a single free parameter. Beyond this, no wake model is used. It is shown that when the thrust coefficient is ‘high’ a maximisation of overall power output leads to a large drop in power after the first turbine, followed by a fairly constant level and a rise at the end of the row; this behaviour is a natural consequence of optimisation, and on this basis a ‘deep array effect’ is to be expected. A variation of turbine size and the effect of impaired turbine performance are examined. The approach can also be used to calculate the turbine upstream velocity (with respect to a reference) from a distribution of measured power output and to make inferences about wake development. The approach could be useful in the assessment of wake models as well as turbine operation.
Balancing of Wind Power Variations Using Norwegian Hydro Power
Authors: Korpås Magnus , Trötscher Thomas , Völler Steve , Tande John Olav
Published: March 2013

This paper addresses the role of Norwegian hydro power to provide balancing power to a future wind dominated European power system. Two power market models, one simplified and one detailed are used to model possible responses of Norwegian hydro power to a wind driven exchange pattern for various amounts of exchange capacity. The case analysed assume a 2030 scenario for wind generation in Europe and an increase in exchange capacity between Norway and Europe from 2300 MW to 5800 MW. We find that the generation constraints and the exchange capacity, and not the aggregated reservoir size, are the most important limiting factors for the amount of balancing the Norwegian hydro power system can provide.
Experimental Study on Seismic Performance of Strap-Braced Cold-Formed Steel Shear Walls
Authors: Zeynalian Mehran , Ronagh Hamid
Published: March 2013

This paper presents a detailed investigation of the lateral performance of X-strap braced cold-formed steel shear walls and their response modification factor, R. Four full-scale 2.4 × 2.4 m specimens with different configurations were tested, and their responses recorded under a standard cyclic loading regime. Of particular interest were the specimens' maximum lateral load capacity and deformation behaviour as well as a rational estimation of the seismic response modification factor. The study also looks at the failure modes of the system and investigates the main factors contributing to the ductile response of the cold formed steel (CFS) shear walls in order to suggest improvements so that the shear steel walls respond plastically with a significant drift and without any risk of brittle failure, such as connection failure or stud buckling. The walls tested have different number of strap elements with different angles, and brackets. The study shows that the performance of this kind of CFS lateral resistant system under cyclic loads is satisfactory; and can be considered reliable. A discussion on the calculated response factors in comparison to those suggested in the relevant codes of practice is also presented.
Failure Analysis of a Cable Dome Due to Cable Slack or Rupture
Authors: Zhu Ming-Liang , Dong Shi-Lin , Yuan Xing-Fei
Published: March 2013

Cable dome is a new type of spatial structure, consisting of cables and struts. Its properties such as its static, dynamic and stability behavior were widely studied, but the failure of the dome is rarely investigated due to its complexity and the limitation of traditional methods. The Vector Form Intrinsic Finite Element method (VFIFE) is a recently proposed method based on a combination of vector mechanics and numerical calculation. Without establishing the stiffness matrix, it is easy to solve problems related to rigid body motion, large deformation and large displacement. It is thus used to simulate the whole failure process of cable domes. The fundamentals of VFIFE are first summarized and the formulations for rod elements and prestressed cable elements are presented. Then the failure analysis of a dome due to cable slack or rupture is conducted by taking a Levy cable dome as an example. Numerical results show that the dome can continue to bear load after some cables slack and will fail after some hoop cable rupture. The dynamic effects caused by cable rupture should not be ignored. Numerical results also indicate that the VFIFE method is effective in the full-process analysis of structures involving rigid body motion, large deformation or vibrations.
Crack Spacing and Width of Thick High Strength Reinforced Concrete Panels
Authors: Dawood Nabil F.A. , Marzouk H.
Published: March 2013

Experimental program involved testing of eighteen panels to study the cracking behavior of thick high strength concrete panels subjected to in-plane tensile forces, was conducted. The influence of different parameters such as concrete strength fc′, reinforcement ratio ρeff, concrete cover to bar diameter ratio ( Cc/ db), and applying axial or biaxial loading, was critically examined. Model equations developed for predicting crack spacing and width of thick concrete plates were discussed.

Using high strength concrete reduced the average crack width measured at every steel stress level. The bar spacing and the concrete cover showed a significant influence on the crack spacing and consequently on the measured crack width. Panels tested under biaxial loading triggered higher crack spacing and crack width compared with the corresponding panels subjected to axial loading. Design equations for predicting the crack spacing and width of thick concrete members are presented parallel with the available code provisions.
Simultaneous Measurement of Wind Pressures and Flow Patterns for Buildings with Interference Effect
Authors: Kim Wonsul , Tamura Yukio , Yoshida Akihito
Published: March 2013

This present study investigated interference effects of local peak pressure on a principal building for various locations of an interfering building for various wind directions. To obtain further information and to explain the interference mechanism for enhanced local peak pressure due to the interfering building, simultaneous pressure measurements and flow visualizations using a dynamic particle image velocimetry (DPIV) system were performed in the wind tunnel of the Shimizu Institute of Technology. Experimental results have been examined and presented of effects of an interfering building and wind direction on local peak pressures. DPIV results have shown that, for an oblique configuration, a strong shear layer generated by the interfering building directly hits the principal building, which increases the momentum over its upper surface, resulting in a high pressure coefficient near the leading edge of its upper surface.
Risk Based Seismic Assessment of Structures
Authors: Khaloo Alireza , Tonekaboni Mehdi
Published: March 2013

In this paper a new approach to risk based seismic assessment of structures is proposed based on acceptable risk levels. In this approach, the probabilistic seismic vulnerability, predicted lifetime of structure, importance and knowledge factors are considered in the evaluation process. Park & Ang damage index is used to quantify damage states of structure. By performing several incremental dynamic analyses, all damage states of structure from minor to heavy and collapse are considered under all possible ground motions. The structural risk level and the necessity of seismic retrofit measures are specified by seismic risk index of structure. This probabilistic performance based method is simple and effective, and therefore, can be incorporated in future seismic assessment codes. At the end, an example of typical RC frames, in the central region of Tehran with high seismic activity, is assessed for seismic risk to illustrate the application of suggested method.
Seismic Response of Elevated Liquid Storage Tanks Using Double Concave Friction Pendulum Bearings with Tri-Linear Behavior
Authors: Rabiei Montazar , Khoshnoudian Faramarz
Published: March 2013

In the current paper, the seismic response of elevated liquid storage tanks using double concave friction pendulum bearings (DCFP) considering bi-linear and tri-linear behaviors have been investigated. After deriving the coupled differential equations of motion, the MATLAB programming language is employed to solve the differential equations in each time step in order to obtain the time history response of isolated tank under near fault ground motions. The advantages and disadvantages of tri-linear behavior over bi-linear one on the response of isolated tanks is scrutinized by studying the effects of main parameters such as isolation period, tank period with fixed base, tank aspect ratio and base mass ratio on the tank response. It is demonstrated that change in bearing behavior form bi-linear to tri-linear dramatically affects the bearing maximum displacement while the peak value of other parameters such as sloshing displacement or tower shear force may experience less variations.
Nonlinear Finite Element Analyses of Steel/FRP-Reinforced Concrete Beams by Using a Novel Composite Beam Element
Authors: Zhang Y.X. , Lin Xiaoshan
Published: March 2013

A simple displacement-based one-dimensional two-node layered composite beam element with only two degrees of freedom per node is developed based on Timoshenko's composite beam functions for nonlinear finite element analyses of steel/FRP-reinforced concrete beams in this paper. Timoshenko's composite beam functions are employed to represent the displacement interpolation functions, and thus the element gives a unified formulation for both slender and moderately deep composite beams and the notorious shear-locking problem is avoided naturally. Geometric nonlinearity and material nonlinearity are included in the new model, and tension-stiffening effect after cracking is also accounted for. The proposed composite beam element is validated against numerical examples, and it is demonstrated to be accurate and effective for analyses of slender and moderately deep composite beams even with very coarse meshes. The element is then employed to analyse the nonlinear structural behaviour of composite steel/FRP-reinforced concrete beams with different parameters, such as different types of reinforcing bars (steel, GFRP, CFRP and BFRP) and different ratios of reinforcement, and the influences of these parameters on the structural behaviour are investigated. The progressive cracking processes of the concrete beams with the increase of loading are also modelled using the proposed element and the results are presented in this paper.
Aided Diagnosis of Structural Pathologies with an Expert System
Authors: Bernat Ernest , Gil Lluís
Published: March 2013

Sustainability and safety are social demands for long-life buildings. Suitable inspection and maintenance tasks on structural elements are needed for keeping buildings safely in service. Any malfunction that causes structural damage could be called pathology by analogy between structural engineering and medicine. Even the easiest evaluation tasks require expensive training periods that may be shortened with a suitable tool. This work presents an expert system (called Doctor House or DH) for diagnosing pathologies of structural elements in buildings. DH differs from other expert systems when it deals with uncertainty in a far easier but still useful way and it is capable of aiding during the initial survey ‘in situ’, when damage should be detected at a glance. DH is a powerful tool that represents complex knowledge gathered from bibliography and experts. Knowledge codification and uncertainty treatment are the main achievements presented. Finally, DH was tested and validated during real surveys.
Seasonal Variation of Surface Chloride Ion Content and Chloride Diffusion Coefficient in a Concrete Dock
Authors: Zhao Yu-Xi , Chen Can , Gao Xiang-Jie , Jin Wei-Liang
Published: March 2013

Concrete powder collected in-situ from a 5-year-old concrete dock in four seasons respectively was tested by rapid chloride test (RCT). Based on Fick's second law, the surface chloride ion content and the chloride diffusion coefficient are derived by regression analysis, and the seasonal variation laws of the two parameters are discussed. Both parameters vary with the season as single-peak laws. The surface chloride ion content reaches the peak value in summer, while the peak of the chloride diffusion coefficient occurs in spring. Possible reasons for these phenomena are discussed in this paper. Finally, the choice of inspection time for those two parameters in different engineering applications is advised and this may make contribution to more accuracy of chloride diffusion prediction in engineering applications.
Free Vibration of a Functionally Graded Rotating Timoshenko Beam Using FEM
Authors: Mohanty S.C. , Dash R.R. , Rout T.
Published: March 2013

Free vibration analysis of functionally graded ordinary (FGO) and functionally graded sandwich (FGSW) rotating cantilever beam is carried out using finite element method. The properties along the thickness of FGO beam and along the thickness of the core of FGSW beam are assumed to follow power law as well as exponential law. The increase in the parameters for rotary inertia, hub radius and rotational speed, increase the first two mode frequencies of both the beams no matter how the properties vary along the thickness of beams. The effect of property distribution laws on the frequencies is found to be predominant for lower values of rotary inertia parameter and for higher values of rotational speed parameter and hub radius parameter. The first two mode frequencies of FGSW beam increase with increase in the thickness of functionally graded material (FGM) core.
Structural Reliability Based on Genetic Algorithm-Monte Carlo (GAMC)
Authors: Jahani Ehsan , Shayanfar Mohsen A. , Barkhordari Mohammad A.
Published: March 2013

There are many different methods to solve the reliability problems. Although Genetic Algorithm (GA), as a heuristic method, and Monte Carlo (MC), as a simulation method, are robust methods but they also suffer from some shortcomings. GA in problems with many random variables and MC in problems with high reliability indices perform improperly. In this paper, a new method is proposed with combining GA and MC which is called GAMC. This method (GAMC) removes the drawbacks of GA and MC. In other words, GAMC can solve reliability problems with many random variables and high reliability indices.
The Contested Cluster Concept: Paradoxical Pathways to Nordic Innovations
Authors: Lindberg Malin , Säll Line
Published: March 2013

The cluster concept has had great influence on national and regional policies for growth and innovation in Sweden since it was introduced in the late 1990s. This article argues that while the cluster concept has been relatively uncontested on the national policy arena, it has been contested on the regional arena regarding its meaning and proper use. We scrutinize this contestation as a matter of power struggles between different actors concerning the preferential right of interpretation of which organizations, areas and innovations are to be considered as important in policies and practices promoting clusters. The article thus highlights the tricky balance act performed by policy makers and civil servants when deciding on prioritization versus diversification. The article contributes to the further development of both policies and theories on growth and innovation by empirically mapping and discussing the impact of power struggles on clusters as pathways to innovation. In order to exemplify these struggles, our study draws upon two separate studies: one of how the cluster concept has been used as a policy measure over time on national and regional level in Sweden (Säll, 2012) and another of the organization of alternative clusters by Women Resource Centers throughout Sweden (Lindberg et al., 2012). Comparing these two cases makes it evident that the perceptions of clusters that harmonize with prevalent hegemonic discourses of growth and innovation have to large extent enjoyed the preferential right of interpretation, however are at the same time challenged by alternative conceptions of clusters. When highlighted in relation to existing research on innovation, growth policy and power relations, the two empirical examples stand out as interesting cases of how innovation policy has been introduced as academic theory, translated to a political context and subject for contestations that has changed the initial meaning of the concept. Ultimately, it is concluded that the pathways to innovation in the Nordic countries are paradoxical, due to the paradoxical pathway of policies and practices to evoke innovation and change as the same as preserving traditional regional power structures.
Finite Element Prediction of Multi-Size Particulate Flow through Three-Dimensional Channel: Code Validation
Authors: Pagalthivarthi K. V. , Visintainer R. J.
Published: March 2013

Multi-size particulate dense slurry flow through three-dimensional rectangular channel is modeled using penalty finite elements with 8-noded hexahedral elements. The methodology previously developed for two-dimensional channel is extended. The computed eddy viscosity of the pure carrier flow is modified to account for the presence of solid particles. Predictions from Spalart-Almaras and k-ε turbulence models are compared to show consistency of trends in results. Results are also found to compare well with experimental results from the literature.
Correlation of Ice-Rafted Detritus in South Atlantic Sediments with Climate Proxies in Polar Ice over the Last Glacial Period
Authors: Kanfoush Sharon L.
Published: March 2013

Previous study identified 6–7 millennial-scale episodes of South Atlantic ice-rafted sediment deposition (SA events) during the glaciation. Questions remain, however, regarding their origin, significance for sea-ice and/or Antarctic ice-sheet dynamics, and relationship to climate. Here I correlate sediment core (TTN057–21) SA events to Greenland and Antarctic ice using two independent methods, stable isotopes and geomagnetic paleointensity, placing SA events in the context of polar climate change in both hemispheres. Marine isotopic stage (MIS) 3 SA events generally coincided with Greenland interstadials and with cooling following Antarctic warm events (A1-A4). This anti-phase behavior is best illustrated when SA0 coincided with both the Antarctic Cold Reversal and Bolling-Allerod warming in Greenland. Moreover, SA events coincide with sea-level rises during the deglaciation (mwp1A) and MIS 3 (30.4, 38.3, 43.7, 51.5 ka), implying unpinning of grounded Weddell Sea region ice masses discharged debris-laden bergs that had a chilling effect on South Atlantic surface temperatures.
Wave Interaction with a Double Chamber Oscillating Water Column Device
Authors: Wilbert R. , Sundar V. , Sannasiraj S.A.
Published: March 2013

The principle of oscillating water column within a chamber due to the propagating oscillatory ocean waves being converted into clean energy through wave energy convertor referred to as Oscillating water column (OWC) device is a well proven concept that still remains as one of the most promising alternate sources of energy from the Ocean. The OWC has single column of water oscillation, whereas, Double Chamber Oscillating Water Column (DCOWC) has two chambers of water oscillation. DCOWC is relatively a new concept. In this paper, the performance characteristics of a DCOWC is evaluated through a well-controlled experimental investigation in a wave flume. The conceptual design aspect of DCOWC and its uniqueness compared with the present state of art in wave energy converters (WECs) are explained. The efficiency of the system is assessed by considering the variations in the geometrical dimensions of the system along with the different characteristics of incident waves. The methodology adopted for evaluating the hydrodynamic performance in terms of energy conversion efficiency, the development of additional structural stability and the wave amplification at the mouth are discussed and its significances are highlighted by presenting the results in a dimensionless form. The analysis of the results indicates the feasibility of the DCOWC concept in harnessing energy from the waves.