bluuebunny/crossref_metadata_2025 huggingface dataset:
Coproduction of Government Services and the New Information Technology: Investigating the Distributional Biases
Authors: Clark Benjamin Y. , Brudney Jeffrey L. , Jang Sung‐Gheel
Published: August 2013

This article investigates how communications advances affect citizens’ ability to participate in coproduction of government services. The authors analyze service requests made to the City of Boston during a one‐year period from 2010 to 2011 and, using geospatial analysis and negative binomial regression, investigate possible disparities by race, education, and income in making service requests. The findings reveal little concern that 311 systems (nonemergency call centers) may benefit one racial group over another; however, there is some indication that Hispanics may use these systems less as requests move from call centers to the Internet and smartphones. Consistent with prior research, the findings show that poorer neighborhoods are less likely to take advantage of 311 service, with the notable exception of smartphone utilization. The implications for citizen participation in coproduction and bridging the digital divide are discussed.
Association of hospitalizations for asthma with seasonal and pandemic influenza
Authors: Gerke Alicia K. , Yang Ming , Tang Fan , Foster Eric D. , Cavanaugh Joseph E. , Polgreen Philip M.
Published: August 2013

Background and objective

Although influenza has been associated with asthma exacerbations, it is not clear the extent to which this association affects health care use in the United States. The first goal of this project was to determine whether, and to what extent, the incidence of asthma hospitalizations is associated with seasonal variation in influenza. Second, we used influenza trends (2000–2008) to help predict asthma admissions during the 2009 H1N1 influenza pandemic.

Methods

We identified all hospitalizations between 1998 and 2008 in the Nationwide Inpatient Sample from the Healthcare Cost and Utilization Project during which a primary diagnosis of asthma was recorded. Separately, we identified all hospitalizations during which a diagnosis of influenza was recorded. We performed time series regression analyses to investigate the association of monthly asthma admissions with influenza incidence. Finally, we applied these time series regression models using 1998–2008 data, to forecast monthly asthma admissions during the 2009 influenza pandemic.

Results

Based on time series regression models, a strong, significant association exists between concurrent influenza activity and incidence of asthma hospitalizations (P‐value < 0.0001). Use of influenza data to predict asthma admissions during the 2009 H1N1 pandemic improved the mean squared prediction error by 60.2%.

Conclusions

Influenza activity in the population is significantly associated with asthma hospitalizations in the United States, and this association can be exploited to more accurately forecast asthma admissions. Our results suggest that improvements in influenza surveillance, prevention and treatment may decrease hospitalizations of asthma patients.
Optimal Designs for Dose Finding Studies with an Active Control
Authors: Dette Holger , Kiss, Christine , Benda Norbert , Bretz Frank
Published: August 2013

Dose finding studies often compare several doses of a new compound with a marketed standard treatment as an active control. In the past, however, research has focused mostly on experimental designs for placebo controlled dose finding studies. To the best of our knowledge, optimal designs for dose finding studies with an active control have not been considered so far. As the statistical analysis for an active controlled dose finding study can be formulated in terms of a mixture of two regression models, the related design problem is different from what has been investigated before in the literature. We present a rigorous approach to the problem of determining optimal designs for estimating the smallest dose achieving the same treatment effect as the active control. We determine explicitly the locally optimal designs for a broad class of models employed in such studies. We also discuss robust design strategies and determine related Bayesian and standardized minimax optimal designs. We illustrate the results by investigating alternative designs for a clinical trial which has recently appeared in a consulting project of one of the authors.
The Joint Graphical Lasso for Inverse Covariance Estimation Across Multiple Classes
Authors: Danaher Patrick , Wang Pei , Witten Daniela M.
Published: August 2013

We consider the problem of estimating multiple related Gaussian graphical models from a high dimensional data set with observations belonging to distinct classes. We propose the joint graphical lasso, which borrows strength across the classes to estimate multiple graphical models that share certain characteristics, such as the locations or weights of non-zero edges. Our approach is based on maximizing a penalized log-likelihood. We employ generalized fused lasso or group lasso penalties and implement a fast alternating directions method of multipliers algorithm to solve the corresponding convex optimization problems. The performance of the method proposed is illustrated through simulated and real data examples.
Sociodemographic and Clinical Differences Between Suicide Ideators and Attempters: A Study of Mood Disordered Patients 50 Years and Older
Authors: Pompili Maurizio , Innamorati Marco , Di Vittorio Cristina , Sher Leo , Girardi Paolo , Amore Mario
Published: August 2013

Our study sought to characterize mood disordered suicide ideators and attempters 50 years and older admitted to a psychiatric ward either for a recent suicide attempt or for ongoing suicidal ideation. We enrolled 50 patients with suicide ideation consecutively admitted to an inpatient department and 50 patients admitted for a suicide attempt made in the last 48 hours. Suicide attempters more frequently had low social support and an age of onset of mood disorder of 46 years and older, and less frequently had a history of suicidal behaviors in the family members and pharmacological treatment, despite the fact that the groups did not differ with regard to antidepressants prescribed. The groups were not distinguishable based on several variables assumed to be risk factors for suicide behavior, such as proximal life events and stressors or alcohol use disorders. In both samples, comorbidity with organic diseases, the presence of stressful life events in the past 12 months, and a diagnosis of major depression were frequently reported. In conclusion, the presence of low social support and the absence of a pharmacotherapy may increase suicidal behaviors in patients at risk.
The Wild Side of Agro‐food Studies: On Co‐experimentation, Politics, Change, and Hope
Authors: Carolan Michael S.
Published: August 2013

Noting that the field of agro‐food studies has undergone numerous ‘turns’ over the years, this article first seeks to make sense of this evolving literature by examining aspects of the metaphysical foreground upon which this ‘turning’ takes place. Doing this highlights a coalescing of sorts within the field; a movement the author describes as being less toward a specific theoretical framework as it is around a general way of doing agro‐food scholarship. This style of scholarship embraces relationality, process, and multiplicity while emphasising the generative capacities of what agro‐food scholars do for enacting novel political, ontological, and normative practices. The reminder of the article co‐experiments with what it means to be open to these productive capacities as researchers, in terms of making the un‐thought thinkable and un‐doable routine. In doing this the article offers an account of agro‐food imaginaries that is hopeful precisely because it is unsettling.
‘Our Entire People are Natural Born Friends of Peace’: The Norwegian Foreign Policy of Peace
Authors: Leira Halvard
Published: August 2013

What makes a peace nation? In this article it is argued that the Norwegian foreign policy of peace is rooted in an historical self‐understanding of Norway and Norwegians as particularly peaceful, an identity which was first articulated around 1890. Norwegians hold a strong liberal/meliorist belief that the world can become a better place, and that Norway has an important role to play in this process. However, this general belief in peace and a Norwegian peaceful exceptionalism has been expressed in different ways over the last 120 years. Around 1900, the ideal was a passive state and an active people working for peace, while from around 1920 it was accepted that the state needed to take more active part. Where international peace activism was associated in particular withUNpeacekeeping during the Cold War, and peace mediation during the 1990's, increasingly a broader panoply of ‘good’ issues have been tied to an ever expanding notion of peace. The last two decades have also seen increased Norwegian participation in offensive military actions, couched at least partly in terms of peace. That the Norwegian attachment to peace remains strong while still allowing for support to military action suggests both that the Norwegian self‐understanding as a peace nation is deeply rooted and that it allows for a self‐righteous understanding of ‘peace through war’.
Low incidence of Pneumocystis jirovecii pneumonia in an unprophylaxed liver transplant cohort
Authors: Sarwar S. , Carey B. , Hegarty J.E. , McCormick P.A.
Published: August 2013

Background

Liver transplant recipients are managed with a range of immunosuppressive regimens that place them at heightened risk of life‐threatening opportunistic infections such as Pneumocystis jirovecii pneumonia (PJP). No routine PJP prophylaxis is used at out institution. We reviewed the incidence of PJP in this cohort of unprophylaxed liver transplant recipients.

Methods

We examined all liver transplants performed between January 2000 and January 2012 in Ireland's National Liver Transplant Centre, St. Vincent's University Hospital, Dublin. Cases were identified through a computerized database and through the histopathology and microbiology registration system. The diagnosis of PJP was confirmed by identification of Pneumocystis cysts in bronchoalveolar lavage (BAL) fluid or on autopsy specimens using Grocott–Gomori methenamine‐silver nitrate or modified Wright–Giemsa staining methods.

Results

During the study period, 687 liver transplants were performed. We found 7 cases of PJP with an incidence rate of 0.84 per 1000 person transplant years. Five cases occurred within 12 months of transplant with 2 cases occurring at 56 and 60 months, respectively. Two cases were diagnosed at postmortem; 1 previously had negative cytology from BAL, while the other could not be bronchoscoped because of rapid deterioration in the clinical condition. Three of the 5 treated patients died.

Conclusions

The incidence of PJP in this cohort was very low, but the case fatality rate was high. Two cases occurred well after the usual recommended period of prophylaxis. In institutions with a very low risk of infection, targeted rather than universal prophylaxis may be reasonable.
A 22‐nt artificial microRNA mediates widespread RNA silencing in Arabidopsis
Authors: McHale Marcus , Eamens Andrew L. , Finnegan E. Jean , Waterhouse Peter M.
Published: August 2013

It is known that 22‐nucleotide (nt) microRNAs (miRNAs) derived from asymmetric duplexes trigger phased small‐interfering RNA (phasiRNA) production from complementary targets. Here we investigate the efficacy of 22‐nt artificial miRNA (amiRNA)‐mediated RNA silencing relative to conventional hairpin RNA (hpRNA) and 21‐nt amiRNA‐mediated RNA silencing. CHALCONE SYNTHASE (CHS) was selected as a target in Arabidopsis thaliana due to the obvious and non‐lethal loss of anthocyanin accumulation upon widespread RNA silencing. Over‐expression of CHS in the pap1‐D background facilitated visual detection of both local and systemic RNA silencing. RNA silencing was initiated in leaf tissues from hpRNA and amiRNA plant expression vectors under the control of an Arabidopsis RuBisCo small subunit 1A promoter (SSU). In this system, hpRNA expression triggered CHS silencing in most leaf tissues but not in roots or seed coats. Similarly, 21‐nt amiRNA expression from symmetric miRNA/miRNA* duplexes triggered CHS silencing in all leaf tissues but not in roots or seed coats. However, 22‐nt amiRNA expression from an asymmetric duplex triggered CHS silencing in all tissues, including roots and seed coats, in the majority of plant lines. This widespread CHS silencing required RNA‐DEPENDENT RNA POLYMERASE6‐mediated accumulation of phasiRNAs from the endogenous CHS transcript. These results demonstrate the efficacy of asymmetric 22‐nt amiRNA‐directed RNA silencing and associated phasiRNA production and activity, in mediating widespread RNA silencing of an endogenous target gene. Asymmetric 22‐nt amiRNA‐directed RNA silencing requires little modification of existing amiRNA technology and is expected to be effective in suppressing other genes and/or members of gene families.
Occult hepatitis B infections among blood donors in Lao PDR
Authors: Jutavijittum P. , Andernach I. E. , Yousukh A. , Samountry B. , Samountry K. , Thammavong T. , Keokhamphue J. , Toriyama K. , Muller C. P.
Published: August 2013

Background and Objectives

In Lao People's Democratic Republic, hepatitis B virus is highly endemic. However, blood donations are only screened for HBsAg, leaving a risk of transmission by HBsAg‐negative occult infected donors. Here, we characterized first‐time blood donors to assess prevalence of hepatitis B virus infections and occult infected donors.

Materials and Methods

Sera were screened for HBsAg, HBeAg and anti‐HBs, anti‐HBc and anti‐HBe antibodies. Occult HBV infections (OBIs) were assessed in HBsAg‐negative sera by PCR, and sera of HBsAg positive and occult infected donors were phylogenetically characterized.

Results

9·6% of the donors were HBsAg positive, and 45.5% were positive for at least one of the hepatitis B virus serum markers. More than 40% HBsAg carriers were HBeAg positive, with HBeAg seroconversion occurring around 30 years of age. Furthermore, 10·9% of HBsAg‐negative, anti‐HBc and/or anti‐HBs‐positive donors were occult infected with hepatitis B virus. Thus, at least 3·9% of blood donations would potentially be unsafe, but hepatitis B virus DNA copy numbers greatly varied between donors.

Conclusion

In Lao People's Democratic Republic, a sizable proportion of HBsAg‐negative and anti‐HBc antibody‐positive blood donations are potentially DNA positive and infective for hepatitis B.
Acceleration of cutaneous wound healing by brassinosteroids
Authors: Esposito Debora , Rathinasabapathy Thirumurugan , Schmidt Barbara , Shakarjian Michael P. , Komarnytsky Slavko , Raskin Ilya
Published: August 2013

Brassinosteroids are plant growth hormones involved in cell growth, division, and differentiation. Their effects in animals are largely unknown, although recent studies showed that the anabolic properties of brassinosteroids are possibly mediated through the phosphoinositide 3‐kinase/protein kinase B signaling pathway. Here, we examined biological activity of homobrassinolide (HB) and its synthetic analogues in in vitro proliferation and migration assays in murine fibroblast and primary keratinocyte cell culture. HB stimulated fibroblast proliferation and migration and weakly induced keratinocyte proliferation in vitro. The effects of topical HB administration on progression of wound closure were further tested in the mouse model of cutaneous wound healing. C57BL/6J mice were given a full‐thickness dermal wound, and the rate of wound closure was assessed daily for 10 days, with adenosine receptor agonist CGS‐21680 as a positive control. Topical application of brassinosteroid significantly reduced wound size and accelerated wound healing in treated animals. mRNA levels of transforming growth factor beta and intercellular adhesion molecule 1 were significantly lower, while tumor necrosis factor alpha was nearly suppressed in the wounds from treated mice. Our data suggest that topical application of brassinosteroids accelerates wound healing by positively modulating inflammatory and reepithelialization phases of the wound repair process, in part by enhancing Akt signaling in the skin at the edges of the wound and enhancing migration of fibroblasts in the wounded area. Targeting this signaling pathway with brassinosteroids may represent a promising approach to the therapy of delayed wound healing.
Randomized placebo‐controlled human pilot study of cold atmospheric argon plasma on skin graft donor sites
Authors: Heinlin Julia , Zimmermann Julia L. , Zeman Florian , Bunk Wolfram , Isbary Georg , Landthaler Michael , Maisch Tim , Monetti Roberto , Morfill Gregor , Shimizu Tetsuji , Steinbauer Julia , Stolz Wilhelm , Karrer Sigrid
Published: August 2013

Cold atmospheric plasma has already been shown to decrease the bacterial load in chronic wounds. However, until now it is not yet known if plasma treatment can also improve wound healing. We aimed to assess the impact of cold atmospheric argon plasma on the process of donor site healing. Forty patients with skin graft donor sites on the upper leg were enrolled in our study. The wound sites were divided into two equally sized areas that were randomly assigned to receive either plasma treatment or placebo (argon gas) for 2 minutes. Donor site healing was evaluated independently by two blinded dermatologists, who compared the wound areas with regard to reepithelialization, blood crusts, fibrin layers, and wound surroundings. From the second treatment day onwards, donor site wound areas treated with plasma (n = 34) showed significantly improved healing compared with placebo‐treated areas (day 1, p = 0.25; day 2, p = 0.011; day 3, p < 0.001; day 4, p < 0.001; day 5, p = 0.004; day 6, p = 0.008; day 7, p = 0.031). Positive effects were observed in terms of improved reepithelialization and fewer fibrin layers and blood crusts, whereas wound surroundings were always normal, independent of the type of treatment. Wound infection did not occur in any of the patients, and no relevant side effects were observed. Both types of treatment were well tolerated. The mechanisms contributing to these clinically observed effects should be further investigated.
Adipose tissue‐derived stem cells (ADSCs) transplantation promotes regeneration of expanded skin using a tissue expansion model
Authors: Sheng Lingling , Yang Mei , Liang Yimin , Li Qingfeng
Published: August 2013

Transplantation of adipose tissue‐derived stem cells (ADSCs) is a promising method that has been used in regenerative medicine because it has shown the capacity to accelerate wound healing. However, roles ofADSCs transplantation in expanded‐skin regeneration have remained unknown. To clarify the roles, a tissue expansion model was used in this study. The study comprised three groups of 13 rats in each group: theADSCs group, the fibroblast (FB) group, and the control group. The skin regeneration in theADSCs group was enhanced, as evidenced by increased cell proliferation and a higher hydroxyproline content and degree of neovascularization, all withp < 0.05, when compared with both theFBgroup and the control group. Consistent with enhanced cell proliferation and neovascularization, the regenerated skin in theADSCs group was much thicker, which further reduced the retraction ratio of the expanded skin. Four weeks after operation, 5'‐bromo‐2'‐deoxyuridine‐labeledADSCs appeared in subcutaneous tissue, vascular vessels, and hair follicles. The up‐regulation of protein expression, such as epidermal growth factor and vascular endothelial growth factor, primarily emerged in theADSCgroup, with the up‐regulated basic fibroblast growth factor appearing in theFBgroup. Collectively, these results suggest that the transplantation ofADSCs could enhance the regeneration of expanded skin by participating in skin structures and up‐regulating the secretion of epidermal growth factor and vascular endothelial growth factor.
Fully automated algorithm for wound surface area assessment
Authors: Deana Alessandro Melo , de Jesus Sérgio Henrique Costa , Sampaio Brunna Pileggi Azevedo , Oliveira Marcelo Tavares , Silva Daniela Fátima Teixeira , França Cristiane Miranda
Published: August 2013

Worldwide, clinicians, dentists, nurses, researchers, and other health professionals need to monitor the wound healing progress and to quantify the rate of wound closure. The aim of this study is to demonstrate, step by step, a fully automated numerical method to estimate the size of the wound and the percentage damaged relative to the body surface area (BSA) in images, without the requirement for human intervention. We included the formula for BSA in rats in the algorithm. The methodology was validated in experimental wounds and human ulcers and was compared with the analysis of an experienced pathologist, with good agreement. Therefore, this algorithm is suitable for experimental wounds and burns and human ulcers, as they have a high contrast with adjacent normal skin.
An in vitro wound healing model for evaluation of dermal substitutes
Authors: van Kilsdonk Jeroen W. J. , van den Bogaard Ellen H. , Jansen Patrick A. M. , Bos Charlotte , Bergers Mieke , Schalkwijk Joost
Published: August 2013

Reepithelialization of skin wounds is essential to restore barrier function and prevent infection. This process requires coordination of keratinocyte proliferation, migration, and differentiation, which may be impeded by various extrinsic and host‐dependent factors. Deep, full‐thickness wounds, e.g., burns, are often grafted with dermal matrices before transplantation of split‐skin grafts. These dermal matrices need to be integrated in the host skin and serve as a substrate for neoepidermis formation. Systematic preclinical analysis of keratinocyte migration on established and experimental matrices has been hampered by the lack of suitable in vitro model systems. Here, we developed an in vitro full‐thickness wound healing model in tissue‐engineered human skin that allowed analysis of the reepithelialization process across different grafted dermal substitutes. We observed strong differences between porous and nonporous matrices, the latter being superior for reepithelialization. This finding was corroborated in rodent wound healing models. The model was optimized using lentivirus‐transduced keratinocytes expressing enhanced green fluorescent protein and by the addition of human blood, which accelerated keratinocyte migration underneath the clot. Our model shows great potential for preclinical evaluation of tissue‐engineered dermal substitutes in a medium‐throughput format, thereby obviating the use of large numbers of experimental animals.
Fundamentals of randomized clinical trials in wound care: Reporting standards
Authors: Brölmann Fleur E. , Eskes Anne M. , Sumpio Bauer E. , Mayer Dieter O. , Moore Zena , Ågren Magnus S. , Hermans Michel , Cutting Keith , Legemate Dink A. , Vermeulen Hester , Ubbink Dirk T.
Published: August 2013

In wound care research, available high‐level evidence according to the evidence pyramid is rare, and is threatened by a poor study design and reporting. Without comprehensive and transparent reporting, readers will not be able to assess the strengths and limitations of the research performed. Randomized clinical trials (RCTs) are universally acknowledged as the study design of choice for comparing treatment effects. To give high‐level evidence the appreciation it deserves in wound care, we propose a step‐by‐step reporting standard for comprehensive and transparent reporting of RCTs in wound care. Critical reporting issues (e.g., wound care terminology, blinding, predefined outcome measures, and a priori sample size calculation) and wound‐specific barriers (e.g., large diversity of etiologies and comorbidities of patients with wounds) that may prevent uniform implementation of reporting standards in wound care research are addressed in this article. The proposed reporting standards can be used as guidance for authors who write their RCT, as well as for peer reviewers of journals. Endorsement and application of these reporting standards may help achieve a higher standard of evidence and allow meta‐analysis of reported wound care data. The ultimate goal is to help wound care professionals make better decisions for their patients in clinical practice.
Process Parameter Effects on Dimensional Accuracy of Micro-Injection Moulded Part
Authors: Mani M. R. , Surace R. , Ferreira P. , Segal J. , Fassi I. , Ratchev S.
Published: August 2013

Micro-injection moulding is becoming increasingly important among the available processes for production of micro-electromechanical systems (MEMS) and microsystem technologies (MSTs), and higher number of polymer products is being manufactured by this process. Due to the sensitive nature of applications of this process, such as medical and aerospace applications, achieving high quality parts with high dimensional accuracy is crucial. In this work, a design of experiment (DoE) approach is used. The aim is to study the effects of three process parameters which are commonly used for research in this domain, on the dimensional accuracy of microchannels with different sizes; they are injection velocity, injection pressure, and melt temperature. The study focuses on two polymers, polyoxymethylene (POM) and liquid crystal polymer (LCP). Experimental results showed that higher melt temperature and injection pressure resulted in higher dimensional accuracy. Nevertheless, high settings for the three parameters resulted in higher percentage of flash in most cases. In conclusion, the most influential factors were shown to be melt temperature and injection pressure.
Type Synthesis of 3-DOF Parallel Manipulators With Both a Planar Operation Mode and a Spatial Translational Operation Mode1
Authors: Kong Xianwen
Published: August 2013

Type synthesis of multimode parallel manipulators (PMs) (also parallel manipulators with multiple operation modes) is an open issue in the research on reconfigurable mechanisms and robots. This paper deals with the type synthesis of 3-DOF (degree-of-freedom) parallel manipulators with both a planar operation mode and a spatial translational operation mode. The type synthesis of planar parallel manipulators, which refer to parallel manipulators in which the moving platform undergoes planar motion, is first dealt with using the virtual-chain approach. Types of planar parallel manipulators, including those involving Bennett compositional unit (CU), are obtained. Then, the types of 3-DOF parallel manipulators with both a planar operation mode and a translational operation mode are obtained. This paper focuses on 3-DOF parallel manipulators composed of only revolute joints. This work contributes to the type synthesis of parallel manipulators and can be extended to the type synthesis of other classes of multimode parallel manipulators.
Examining the LEED Rating System Using Inverse Optimization
Authors: Turner Sarina D. O. , Chan Timothy C. Y.
Published: August 2013

The Leadership in Energy and Environmental Design (LEED) rating system is the most recognized green building certification program in North America. In order to be LEED certified, a building must earn a sufficient number of points, which are obtained through achieving certain credits or design elements. In LEED versions 1 and 2, each credit was worth one point. In version 3, the LEED system changed so that certain credits were worth more than one point. In this study, we develop an inverse optimization approach to examine how building designers intrinsically valued design elements in LEED version 2. Because of the change in the point system between version 2 and version 3, we aim to determine whether building designers actually valued each credit equally, and if not, whether their valuations matched the values in version 3. Due to the large dimensionality of the inverse optimization problem, we develop an approximation to improve tractability. We apply our method to 306 different LEED-certified buildings in the continental United States. We find that building designers did not value all credits equally and that other factors such as cost, building type, and size, and certification level play a role in how the credits are valued. Overall, inverse optimization may provide a new method to assess historical data and support the design of future versions of LEED.
Predicting High-Lift Low-Pressure Turbine Cascades Flow Using Transition-Sensitive Turbulence Closures
Authors: Pacciani Roberto , Marconcini Michele , Arnone Andrea , Bertini Francesco
Published: August 2013

This paper discusses the application of different transition-sensitive turbulence closures to the prediction of low-Reynolds-number flows in high-lift cascades operating in low-pressure turbine (LPT) conditions. Different formulations of the well known γ-R˜eθt model are considered and compared to a recently developed transition model based on the laminar kinetic energy (LKE) concept. All those approaches have been coupled to the Wilcox k-ω turbulence model. The performance of the transition-sensitive closures has been assessed by analyzing three different high-lift cascades, recently tested experimentally in two European research projects (Unsteady Transition in Axial Turbomachines (UTAT) and Turbulence and Transition Modeling for Special Turbomachinery Applications (TATMo)). Such cascades (T106A, T106C, and T108) feature different loading distributions, different suction side diffusion factors, and they are characterized by suction side boundary layer separation when operated in steady inflow. Both steady and unsteady inflow conditions (induced by upstream passing wakes) have been studied. Particular attention has been devoted to the treatment of crucial boundary conditions like the freestream turbulence intensity and the turbulent length scale. A detailed comparison between measurements and computations, in terms of blade surface isentropic Mach number distributions and cascade lapse rates will be presented and discussed. Specific features of the computed wake-induced transition patterns will be discussed for selected Reynolds numbers. Finally, some guidelines concerning the computations of high-lift cascades for LPT applications using Reynolds-averaged Navier–Stokes (RANS)/unsteady RANS (URANS) approaches and transition-sensitive closures will be reported.
Thermal pretreatment of sapphire substrates prior to ZnO buffer layer growth
Authors: Huang Shimin , Gu Shulin , Zhu Shunming , Gu Ran , Tang Kun , Ye Jiandong , Zhang Rong , Shi Yi , Zheng Youdou
Published: August 2013

The properties of ZnO buffer layers grown via metal-organic chemical vapor deposition (MOCVD) on sapphire substrates after various thermal pretreatments are systematically investigated. High-temperature pretreatments lead to significant modifications of the sapphire surface, which result in enhanced growth nucleation and a consequent improvement of the surface morphology and quality of the ZnO layers. The evolution of the surface morphology as seen by atomic force microscopy indicates an obvious growth mode transition from three-dimensional to quasi-two-dimensional as the pretreatment temperature increases. A minimum surface roughness is obtained when the pretreatment temperature reaches 1150 °C, implying that a high-temperature pretreatment at 1150 °C or above may lead to a conversion of the surface polarity from O-face to Zn-face, similar to processes in GaN material growth via MOCVD. By analyzing the evolution of the film properties as a function of pretreatment temperature, the optimal condition has been determined to be at 1150 °C. This study indicates that a high-temperature pretreatment is crucial to grow high-quality ZnO on sapphire substrates by MOCVD.
Actively triggered 4d cone‐beam CT acquisition
Authors: Fast Martin F. , Wisotzky Eric , Oelfke Uwe , Nill Simeon
Published: August 2013

Purpose:

4d cone‐beam computed tomography (CBCT) scans are usually reconstructed by extracting the motion information from the 2d projections or an external surrogate signal, and binning the individual projections into multiple respiratory phases. In this “after‐the‐fact” binning approach, however, projections are unevenly distributed over respiratory phases resulting in inefficient utilization of imaging dose. To avoid excess dose in certain respiratory phases, and poor image quality due to a lack of projections in others, the authors have developed a novel 4d CBCT acquisition framework which actively triggers 2d projections based on the forward‐predicted position of the tumor.

Methods:

The forward‐prediction of the tumor position was independently established using either (i) an electromagnetic (EM) tracking system based on implanted EM‐transponders which act as a surrogate for the tumor position, or (ii) an external motion sensor measuring the chest‐wall displacement and correlating this external motion to the phase‐shifted diaphragm motion derived from the acquired images. In order to avoid EM‐induced artifacts in the imaging detector, the authors devised a simple but effective “Faraday” shielding cage. The authors demonstrated the feasibility of their acquisition strategy by scanning an anthropomorphic lung phantom moving on 1d or 2d sinusoidal trajectories.

Results:

With both tumor position devices, the authors were able to acquire 4d CBCTs free of motion blurring. For scans based on the EM tracking system, reconstruction artifacts stemming from the presence of the EM‐array and the EM‐transponders were greatly reduced using newly developed correction algorithms. By tuning the imaging frequency independently for each respiratory phase prior to acquisition, it was possible to harmonize the number of projections over respiratory phases. Depending on the breathing period (3.5 or 5 s) and the gantry rotation time (4 or 5 min), between ∼90 and 145 projections were acquired per respiratory phase resulting in a dose of ∼1.7–2.6 mGy per respiratory phase. Further dose savings and decreases in the scanning time are possible by acquiring only a subset of all respiratory phases, for example, peak‐exhale and peak‐inhale only scans.

Conclusions:

This study is the first experimental demonstration of a new 4d CBCT acquisition paradigm in which imaging dose is efficiently utilized by actively triggering only those projections that are desired for the reconstruction process.
Friend or foe? A review of the mechanisms that driveSerratiatowards diverse lifestyles
Authors: Petersen Lauren M. , Tisa Louis S.
Published: August 2013

Found widespread around the globe, Serratia are Gram-negative bacteria capable of thriving in a diverse number of environments that include water, soil, and the digestive tracts of various animals. Known for their ability to produce a myriad of extracellular enzymes, these bacteria also produce various secondary metabolites that directly contribute to their survival. While the effects Serratia species have on other organisms range from parasitic to symbiotic, what these bacteria have in common is their ability to resist attack, respond appropriately to environmental conditions, and outcompete other microorganisms when colonizing their respective niche. This review highlights the mechanisms utilized by Serratia species that drive their ubiquitous nature, with emphasis on the latest findings. Also discussed is how secreted compounds drive these bacteria towards pathogenic, mutualistic, and antagonistic associations.
Using photographs to elicit student ideas about physics: The case of an unusual liquid-level phenomenon
Authors: Erceg Nataša , Aviani Ivica , Mešić Vanes
Published: August 2013

This work is aimed at exploring some pedagogical opportunities of using photographs in physics instruction. In our study, the photography has been used for eliciting and probing students’ ideas regarding the physics of fluids in noninertial frames of reference and under conditions of equilibrium. The study involved a heterogeneous sample of 235 secondary school students, 41 physics students, and 48 physics teachers. They were presented with a photograph of a wine glass filled with liquid whose surface appeared inclined. The students were asked to comment on the reality of the phenomenon captured in the photograph, and the teachers were asked to predict the students’ responses. The results showed that about half of the students had a complete or partially complete understanding of the physical ideas and that their practical and conceptual knowledge was not dependent on their education level or curriculum followed. Most of the respondents found the task interesting and relevant. The results indicate that the teachers’ expectations regarding students’ understanding of physics often significantly depart from reality. We suggest that physics teachers include some photography-based problems and discussions in their classes. This could encourage a broad participation of students with different levels of abilities.
IMPROVEMENT OF NONVOLATILE BLUE PHOTOREFRACTIVE PROPERTIES IN In:Ce:Cu:LiNbO3 CRYSTALS
Authors: LENG XUESONG , DAI LI , XU CHAO , YANG CHUNHUI , XU YUHENG
Published: August 2013

The In : Ce : Cu : LiNbO 3 crystals used in this work were grown by Czchralski method. The key parameters: the exponential gain coefficient Γ, the diffraction efficiency ηS, the response time τw, the dynamic range M/#, the sensitivity S and the maximal refractive index change Δn max were measured with conventional two beam coupling. The optimal values of Γ, ηS, M/#, S and Δn max achieved are 44.7, 68.6%, 6.02, 0.471 cm/J and 5.37 × 10-5, respectively. It was found that the blue light photorefractive properties of Γ, ηS, M/#, S and Δn max increased with increasing In 3+ ions concentration, while the red light photorefractive properties of Γ, ηS, Δn max decreased with increasing In 3+ ions concentration. The nonvolatile holographic storage properties were measured by both the dual wavelength and two color techniques. The maximal diffraction efficiency and fixing diffraction efficiency using the dual wavelength technique were doubled compared to those obtained in using the two color technique. The sensitivity and nonvolatile sensitivity were one order of magnitude higher than those by the two color technique. The photorefractive property enhancement by the dual wavelength technique was investigated.
TEMPORAL AND SPECTRAL ANALYSIS FOR MID-INFRARED FOUR-WAVE MIXING IN QUANTUM INTERSUBBAND STRUCTURE
Authors: HEKMAT BAKTASH , AHMADI VAHID , DARABI ELHAM
Published: August 2013

We design a quantum cascade (QC) intersubband structure for four-wave mixing (FWM) generation from In 0.53 Ga 0.47 As / In 0.52 Al 0.48 As in the mid-infrared spectral region which can be described by third-order nonlinear optical susceptibility. In this structure, increasing FWM is accomplished by band engineering which modify energy of subbands. To analyze FWM characteristics in a QC structure, the evolution in time and spectral domain of pump and probe input optical pulses with different frequencies during propagation is calculated and simulated by using finite-difference beam propagation method. Central frequencies of pump and probe pulses which are used for driving the amplifier are 37.97 THz and 32.61 THz, respectively. Third order susceptibility responsible for FWM resonance nonlinearity of the structure is enhanced by two orders of magnitude. As power of input pulses rises, the value of the FWM output signal increases but the pulse loses its initial shape. Gain saturation and dispersion play a major role in shaping the output pulse. Results reveal that the FWM optical pulse characteristics are highly sensitive to the pulse power and QC parameters in the time and frequency domains.
CHARACTERIZATION AND ELECTROCHROMIC PROPERTIES OF VANADIUM OXIDE THIN FILMS PREPARED VIA SPRAY PYROLYSIS
Authors: MOUSAVI M. , KOMPANY A. , SHAHTAHMASEBI N. , BAGHERI-MOHAGHEGHI M.-M.
Published: August 2013

Vanadium oxide thin films were grown on glass substrates using spray pyrolysis technique. The effects of substrate temperature, vanadium concentration in the initial solution and the solution spray rate on the nanostructural and the electrochromic properties of deposited films are investigated. Characterization and the electrochromic measurements were carried out using X-ray diffraction, scanning electron microscopy and cyclic voltammogram. XRD patterns showed that the prepared films have polycrystalline structure and are mostly mixed phases of orthorhombic α- V 2 O 5 along with minor β- V 2 O 5 and V 4 O 9 tetragonal structures. The preferred orientation of the deposited films was found to be along [101] plane. The cyclic voltammogram results obtained for different samples showed that only the films with 0.2 M solution concentration, 5 ml/min solution spray rate and 450°C substrate temperature exhibit two-step electrochromic properties. The results show a correlation between cycle voltammogram, morphology and resistance of the films.
A THEORETICAL CALCULATION OF MICROLENSING SIGNATURES CAUSED BY FREE-FLOATING PLANETS TOWARDS THE GALACTIC BULGE
Authors: HAMOLLI L. , HAFIZI M. , NUCITA A. A.
Published: August 2013

Free-floating planets (FFPs) are recently drawing a special interest of the scientific community. Gravitational microlensing is up to now the exclusive method for the investigation of FFPs, including their spatial distribution function and mass function. In this paper, we examine the possibility that the future Euclid space-based observatory may allow to discover a substantial number of microlensing events caused by FFPs. Based on latest results about the free-floating planet (FFP) mass function in the mass range [10-5, 10-2]M⊙, we calculate the optical depth towards the Galactic bulge as well as the expected microlensing rate and find that Euclid may be able to detect hundreds to thousands of these events per month. Making use of a synthetic population, we also investigate the possibility of detecting parallax effect in simulated microlensing events due to FFPs and find a significant efficiency for the parallax detection that turns out to be around 30%.
STOCHASTIC SCENARIO-BASED TIME-STAGE OPTIMIZATION MODEL FOR THE LEAST EXPECTED TIME SHORTEST PATH PROBLEM
Authors: YANG LIXING , YANG XIAOFEI , YOU CUILIAN
Published: August 2013

Focusing on finding a pre-specified basis path in a network, this research formulates a two-stage stochastic optimization model for the least expected time shortest path problem, in which random scenario-based time-invariant link travel times are utilized to capture the uncertainty of the realworld traffic network. In this model, the first stage aims to find a basis path for the trip over all the scenarios, and the second stage intends to generate the remainder path adaptively when the realizations of random link travel times are updated after a pre-specified time threshold. The GAMS optimization software is introduced to find the optimal solution of the proposed model. The numerical experiments demonstrate the performance of the proposed approaches.
MATHEMATICAL PROGRAMMING PROBLEMS WITH SEVERAL FUZZY OBJECTIVE FUNCTIONS
Authors: KALONDA LUHANDJULA MONGA , JOSEPH RANGOAGA MOETI
Published: August 2013

In this paper we propose an approach for multiobjective programming problems with fuzzy number coefficients. The main idea behind our approach is to approximate involved fuzzy numbers by their respective nearest interval approximation counterparts. An algorithm that returns a nearest interval approximation to a given fuzzy number, plays a pivotal role in the proposed method.

Our approach contrasts markedly with those based on deffuzification operators which replace a fuzzy set by a single real number leading to a loss of many important information. A numerical example is also provided for the sake of illustration.
CREDIBILISTIC BIMATRIX GAME WITH ASYMMETRIC INFORMATION: BAYESIAN OPTIMISTIC EQUILIBRIUM STRATEGY
Authors: GAO JINWU , YANG XIANGFENG
Published: August 2013

In credibilistic bimatrix games, the solution concept of (α, β)-optimistic equilibrium strategy was proposed for dealing with the situation that the two players want to optimize the optimistic value of their fuzzy objectives at confidence levels α and β, respectively. This paper goes further by assuming that the confidence levels are private information of the two players. And the so-called credibilistic bimatrix game with asymmetric information is investigated. A solution concept of Bayesian optimistic equilibrium strategy as well as its existence theorem are presented. Moreover, a sufficient and necessary condition is given for finding the Bayesian optimistic equilibrium strategy. Finally, an example is provided for illustrating purpose.
SUPPORT VECTOR MACHINE BASED ON RANDOM SET SAMPLES
Authors: WANG CHAO , HA MINGHU , CHEN JIQIANG , XING HONGJIE
Published: August 2013

In order to deal with learning problems of random set samples encountered in real-world, according to random set theory and convex quadratic programming, a new support vector machine based on random set samples is constructed. Experimental results show that the new support vector machine is feasible and effective.
MEAN-SEMIVARIANCE MODELS FOR PORTFOLIO OPTIMIZATION PROBLEM WITH MIXED UNCERTAINTY OF FUZZINESS AND RANDOMNESS
Authors: QIN ZHONGFENG , WANG DAVID Z. W. , LI XIANG
Published: August 2013

In practice, security returns cannot be accurately predicted due to lack of historical data. Therefore, statistical methods and experts' experience are always integrated to estimate future security returns, which are hereinafter regarded as random fuzzy variables. Random fuzzy variable is a powerful tool to deal with the portfolio optimization problem including stochastic parameters with ambiguous expected returns. In this paper, we first define the semivariance of random fuzzy variable and prove its several properties. By considering the semivariance as a risk measure, we establish the mean-semivariance models for portfolio optimization problem with random fuzzy returns. We design a hybrid algorithm with random fuzzy simulation to solve the proposed models in general cases. Finally, we present a numerical example and compare the results to illustrate the mean-semivariance model and the effectiveness of the algorithm.
AN IMPROVED VIEW FRUSTUM CULLING METHOD USING OCTREES FOR 3D REAL-TIME RENDERING
Authors: DE CARVALHO PAULO ROBERTO , DOS SANTOS MAIKON CISMOSKI , SCHWARTZ WILLIAM ROBSON , PEDRINI HELIO
Published: August 2013

The generation of real-time 3D graphics scenes normally demands high computational requirements. Several applications can benefit from efficient algorithms for rendering complex virtual environments, such as computer games, terrain visualization, virtual reality and visual simulation. This paper describes an improved view frustum culling method using spatial partitioning based on octrees for 3D real-time rendering. The proposed method is compared against two other approaches. Experiments using four different scenes are conducted to evaluate the performance of each tested method. Results demonstrate that the proposed method presents superior frame rate for all scenes.
AMBIGUITY AND LEARNING IN THE INNOVATION PROCESS: MANAGING EXPLOITATION-EXPLOITATION BY BALANCING CREATIVITY AND CONSTRAINT REVISITED
Authors: SÆTRE ALF STEINAR , BRUN ERIC
Published: August 2013

In this paper, we explicate the details of the management of ambiguity and the balancing of creativity and constraint as it relates to organizations' absorptive capacity. The innovation process is characterized by cycles of expensive (explorative) activity where ambiguity increases, and constrictive (exploitative) activities, where ambiguity decreases. We argue that ambiguity oscillates in the short run and decrease in the long run while learning increases. These fluctuations in the opportunity space are driven by the balancing of creativity and constraint.