bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation of graphene/poly(vinyl alcohol) nanocomposites with enhanced mechanical properties and water resistance
Authors: Wang Jingchao , Wang Xianbao , Xu Chunhui , Zhang Min , Shang Xiaopeng
Published: January 2011

The control and dispersal of graphene nanosheets in polymer hosts are challenges in the development of high‐performance graphene‐based nanocomposites due to the strong interlayer cohesive energy and surface inertia. Here we report a simple and practical approach to synthesize graphene‐reinforced poly(vinyl alcohol) (PVA) composite films by incorporating graphene oxide and graphene into PVA aqueous solution. The resulting nanocomposites revealed increases of up to 212% in tensile strength and 34% in elongation at break with only 0.5 wt% graphene content. Water absorption measurements showed that the water absorption ratio of the graphene/PVA composites decreased from 105.2 to 48.8%, and the barrier properties were obviously improved. Contact angle measurements showed that the composites were hydrophobic (θ > 90°) in contrast to the highly hydrophilic (θ < 90°) pure PVA. Copyright © 2011 Society of Chemical Industry
Synthesis of chiral stationary phase via surface‐initiated atom transfer radical polymerization of vinylated cellulose 3,5‐dimethylphenylcarbamate
Authors: Bae In‐Ae , Park Jung‐Hyun , Choi Seong‐Ho
Published: January 2011

A polysaccharide‐immobilized chiral stationary phase (CSP) was prepared by the surface‐initiated atom transfer radical polymerization (SI‐ATRP), in pyridine, of cellulose 2,3‐bis(3,5‐dimethylphenylcarbamate), having a polymerizable vinyl group, on the surface of SiO2 support. The successful preparation of the CSP was confirmed via Fourier transform infrared spectroscopy, field‐emission scanning electron microscopy, X‐ray photoelectron spectroscopy, elemental analysis and thermal analysis. The chiral recognition ability of the prepared CSP was evaluated with high‐performance liquid chromatography using 10 racemates with various mobile phases of hexane/alcohol, hexane/tetrahydrofuran and hexane/chloroform. As a result, this CSP prepared using SI‐ATRP can be used in tetrahydrofuran and chloroform solutions as eluents. Copyright © 2011 Society of Chemical Industry
IκB‐Kinase‐ε (IKKε/IKKi/IκBKε) expression and localization in prostate cancer tissues
Authors: Péant Benjamin , Forest Valérie , Trudeau Vincent , Latour Mathieu , Mes‐Masson Anne‐Marie , Saad Fred
Published: January 2011

BACKGROUND

Advanced prostate cancer (PCa) remains a one of the leading causes of cancer related death and is often due to the progression from a hormone sensitive (HS) to a castrate resistant (CR) state for which therapeutic alternatives remain palliative. Molecular events involved in the progression to CR‐PCa remain largely unknown. A previous study reported significantly higher levels of Iκ‐B kinase‐epsilon (IKKε) expression in CR compared to androgen‐responsive cell lines. In the present study, we evaluate IKKε expression in human prostate tissue.

METHODS

In order to evaluate the modulation of IKKε expression in PCa tissue IKKε immunostaining was performed on paraffin‐embedded prostate tissue microarrays containing cores from normal tissues (n = 47), non‐malignant tissues adjacent to the tumor (n = 53), prostatic intraepithelial neoplasia (PIN) (n = 28), HS (n = 62), and CR tumors (n = 31).

RESULTS

We found a low cytoplasmic expression of IKKε in non‐malignant tissue. HS tumors showed a significant increase in cytoplasmic IKKε expression compared to non‐malignant tissues. CR tissues presented the highest cytoplasmic IKKε expression levels. We also report, for the first time, the presence of a nuclear localization of IKKε in prostate epithelial cells, in particular we observed an increase of IKKε nuclear localization in HS malignant tissues. Finally, we found a strong link between an increase of IKKε cytoplasmic expression in PCa and metastatic progression.

CONCLUSION

This study strongly suggests the role of IKKε as a PCa oncogene that may be involved in the emergence of a CR state. Prostate 71:1131–1138, 2011. © 2011 Wiley‐Liss, Inc.
Prostate cancer outcome and tissue levels of metal ions
Authors: Sarafanov Andrey G. , Todorov Todor I. , Centeno José A. , Macias Virgilia , Gao Weihua , Liang Wei‐Min , Beam Craig , Gray Marion A. , Kajdacsy‐Balla André A.
Published: January 2011

BACKGROUND

There are several studies examining prostate cancer and exposure to cadmium, iron, selenium, and zinc. Less data are available on the possible influence of these metal ions on prostate cancer outcome. This study measured levels of these ions in prostatectomy samples in order to examine possible associations between metal concentrations and disease outcome.

METHODS

We obtained formalin fixed paraffin embedded tissue blocks of prostatectomy samples of 40 patients with PSA recurrence, matched 1:1 (for year of surgery, race, age, Gleason grading, and pathology TNM classification) with tissue blocks from 40 patients without recurrence (n = 80). Case–control pairs were compared for the levels of metals in areas adjacent to tumors. Inductively coupled plasma‐mass spectrometry (ICP‐MS) was used for quantification of Cd, Fe, Zn, and Se.

RESULTS

Patients with biochemical (PSA) recurrence of disease had 12% lower median iron (95 µg/g vs. 111 µg/g; P = 0.04) and 21% lower zinc (279 µg/g vs. 346 µg/g; P = 0.04) concentrations in the normal‐appearing tissue immediately adjacent to cancer areas. Differences in cadmium (0.489 µg/g vs. 0.439 µg/g; 4% higher) and selenium (1.68 µg/g vs. 1.58 µg/g; 5% higher) levels were not statistically significant in recurrence cases, when compared to non‐recurrences (P = 0.40 and 0.21, respectively).

CONCLUSIONS

There is an association between low zinc and low iron prostate tissue levels and biochemical recurrence in prostate cancer. Whether these novel findings are a cause or effect of more aggressive tumors, or whether low zinc and iron prostatic levels raise implications for therapy, remains to be investigated. Prostate 71:1231–1238, 2011. © 2011 Wiley‐Liss, Inc.
Field evaluation of reduced insecticide spray programs for managing plum curculio, Conotrachelus nenuphar (Coleoptera: Curculionidae), in Alabama peaches
Authors: Akotsen‐Mensah Clement , Boozer Robert T , Fadamiro Henry Y
Published: January 2011

BACKGROUND: Plum curculio (PC), Conotrachelus nenuphar (Herbst.), is an important pest of peaches in the southeastern United States. Commercially acceptable control of this insect is typically achieved by weekly or biweekly application of broad‐spectrum conventional insecticides, resulting in 6–12 sprays per season. Experiments were conducted in a peach orchard in Alabama during 2007–2009 to compare the conventional calendar‐based insecticide spray program involving weekly applications of phosmet with three different reduced spray programs using three targeted (well‐timed) insecticide sprays (TIS) of phosmet, permethrin or thiamethoxam applied in an alternated fashion.

RESULTS: All three TIS programs significantly reduced PC damage at harvest compared with the untreated control in two of the three years (2008 and 2009). Fruit damage due to stink bugs, which are emerging pests of peaches in the region, was also significantly reduced in the TIS programs in both years. In a separate trial in which one of the TIS programs (three targeted sprays of phosmet) was evaluated in a larger peach block in 2009, percentage fruit damage due to PC increased from < 1% in June to ∼4% in late July.

CONCLUSION: All the TIS programs evaluated provided effective control of PC and represent potential alternatives to the conventional weekly spray program in peaches with concomitant reduction in insecticide usage and associated costs. However, an additional spray may be necessary for effective control of PC and stink bugs in late‐season peach varieties. Copyright © 2011 Society of Chemical Industry
Comparison of foliar and soil formulations of neonicotinoid insecticides for control of potato leafhopper, Empoasca fabae (Homoptera: Cicadellidae), in wine grapes
Authors: Van Timmeren Steven , Wise John C , VanderVoort Christine , Isaacs Rufus
Published: January 2011

BACKGROUND: The potential of systemic neonicotinoid insecticides to control potato leafhopper, Empoasca fabae (Harris), a damaging pest of wine grapes in the eastern United States, was investigated. Soil or foliar applications were made to potted or field‐grown vines, and the response of leafhoppers was determined in clip cages over the following month on young or mature leaves.

RESULTS: Foliar application of imidacloprid caused immediate and long‐lasting reductions in E. fabae survival on both leaf ages, whereas the activity of soil‐applied imidacloprid was delayed. Clothianidin, imidacloprid and thiamethoxam all provided long‐lasting reduction in leafhopper survival on young and mature foliage when applied through either delivery route. However, the percentage of moribund nymphs was significantly greater on foliar‐treated vines and increased over time in mature and immature leaves compared with soil‐treated vines. Residue analysis of foliar‐applied imidacloprid showed an 89% decline in mature leaves from day 1 to day 27, and a 98% decline in immature leaves over the same time period. Comparison of soil‐applied clothianidin, imidacloprid and thiamethoxam in field‐grown vines showed significant reduction in E. fabae only on mature leaves of vines treated with thiamethoxam.

CONCLUSIONS: Neonicotinoids can control E. fabae in small vines, even in rapidly expanding foliage where this pest causes greatest injury. Soil application provides superior long‐term vine protection because declining residues on foliar‐treated vines lead to suboptimal activity within 2–3 weeks. Vineyard managers of susceptible cultivars may take advantage of this approach to E. fabae management by using foliar applications of the three neonicotinoids tested here, or by using soil‐applied thiamethoxam. Copyright © 2011 Society of Chemical Industry
Resistance to HPPD‐inhibiting herbicides in a population of waterhemp (Amaranthus tuberculatus) from Illinois, United States
Authors: Hausman Nicholas E , Singh Sukhvinder , Tranel Patrick J , Riechers Dean E , Kaundun Shiv S , Polge Nicholas D , Thomas David A , Hager Aaron G
Published: January 2011

BACKGROUND: A population of waterhemp in a seed maize production field in central Illinois, United States, was not adequately controlled after post‐emergence applications of herbicides that inhibit 4‐hydroxyphenylpyruvate dioxygenase (HPPD).

RESULTS: Progeny from the field population survived following treatment with mesotrione, tembotrione or topramezone applied to the foliage either alone or in combination with atrazine in greenhouse experiments. Dose–response experiments indicated that the level of resistance to the HPPD inhibitor mesotrione is at least tenfold relative to sensitive biotypes.

CONCLUSION: These studies confirm that waterhemp has evolved resistance to HPPD‐inhibiting herbicides. Copyright © 2011 Society of Chemical Industry
Application of the electron probe microanalysis in nitride‐based heterostructures investigation
Authors: Kuznetsova Yana , Baidakova Marina , Flegontova Ekaterina , Kuznetsov Anton , Sitnikova Alla , Zamoryanskaya Maria
Published: January 2011

The aim of this work was development of electron probe microanalysis (EPMA) technique suitable for composition determination of nanoscale layers. Proposed technique allows to determine the content of thin layers lying beneath the surface including single quantum wells (SQWs). The method is based on Monte‐Carlo numerical simulations. Application of this technique to the nitride heterostructures with SQWs and multiple quantum wells (MQWs) was demonstrated. Peculiarities of the method are discussed.

magnified image

Electron trajectories in GaN sample with In0.1Ga0.9N single quantum well. Simulation was made by Monte‐Carlo method.
Reduced order model predictive control for constrained discrete‐time linear systems
Authors: Hara N. , Kojima A.
Published: January 2011

A reduced order model predictive control (MPC) is discussed for constrained discrete‐time linear systems. By employing a decomposition method for finite‐horizon linear systems, an MPC law is obtained from a reduced order optimization problem. The decomposition enables us to construct pairs of initial state and control sequence which have large influence on system responses, and it also characterizes the standard LQ control. The MPC law is obtained based on a combination of the LQ control and dominant input sequences over the prediction horizon. The proposed MPC method is illustrated with numerical examples. Copyright © 2011 John Wiley & Sons, Ltd.
Robust ℋ︁∞ PID control for multivariable networked control systems with disturbance/noise attenuation
Authors: Zhang Hui , Shi Yang , Mehr Aryan Saadat
Published: January 2011

In this paper, we study the design problem of PID controllers for networked control systems (NCSs) with polyhedral uncertainties. The load disturbance and measurement noise are both taken into account in the modeling to better reflect the practical scenario. By using a novel technique, the design problem of PID controllers is converted into a design problem of output feedback controllers. Our goal of this paper is two‐fold: (1) To design the robust PID tracking controllers for practical models; (2) To develop the robust ℋ︁∞ PID control such that load and reference disturbances can be attenuated with a prescribed level. Sufficient conditions are derived by employing advanced techniques for achieving delay dependence. The proposed controller can be readily designed based on iterative suboptimal algorithms. Finally, four examples are presented to show the effectiveness of the proposed methods. Copyright © 2011 John Wiley & Sons, Ltd.
Changes in Ultrastructure and properties of bracket slots after Orthodontic treatment with bicuspid extraction
Authors: Choi Samjin , Park Ki‐Ho , Cheong Youjin , Kim Hee‐Kyun , Park Young‐Guk , Park Hun‐Kuk
Published: January 2011

This study examined the effects of an orthodontic treatment using a bicuspid extraction on the surface roughness and mechanical properties of stainless steel (SS) brackets adjacent to the extraction space. Four experimental groups were employed; groups 1 and 2 used the Archist® SS brackets before and after the extraction treatment, respectively, and groups 3 and 4 used the Victory® SS brackets before and after the extraction treatment, respectively. The slot surfaces of the bracket were scanned in air at a resolution of 512 × 512 pixels with a scan speed of 0.8 line/s. The visco‐elasticity of the bracket slot was determined from the force–distance curves of atomic force microscopy. The orthodontic treatment with bicuspid extraction led to a significant increase (p<0.0001) in surface roughness in both groups. In particular, the Archist® SS brackets showed more changes than the Victory® SS brackets (p<0.0005). However, there was no significant difference in properties of the Victory® and Archist® brackets between before and after treatment. This suggests that the orthodontic treatment with bicuspid extraction is more responsible for the changes in surface roughness than the properties of the brackets. SCANNING 33: 25–32, 2011. © 2011 Wiley Periodicals, Inc.
Detection of peptides in high concentration of salts by electrospray droplet impact/secondary ion mass spectrometry
Authors: Asakawa Daiki , Hiraoka Kenzo
Published: January 2011

Electrospray droplet impact (EDI)/SIMS is a new desorption/ionization technique for mass spectrometry. EDI/SIMS utilizes large multiply charged water clusters produced by atmospheric pressure electrospray as primary projectiles. It was found to afford extremely soft desorption/ionization compared with conventional SIMS, and has been used for detection of peptides and proteins. In this study, EDI/SIMS was applied to the detection of peptide in a highly concentrated NaCl solution. The persistent appearance of peptide ions for 1 ppm peptides in NaCl is probably because of the segregation of peptides on the crystallized salts. The samples dried under vacuum gave better EDI/SIMS mass spectra than those under ambient atmospheric pressure. Copyright © 2011 John Wiley & Sons, Ltd.
Electrochemical impedance spectroscopy and in situ UV‐vis spectroelectrochemistry studies of Poly(N‐vinyl carbazole)/ Polydimethylsiloxane composite electrodes
Authors: Gökçeören Argun Talat , Erbil Candan
Published: January 2011

Poly(N‐vinyl carbazole)/polydimethylsiloxane (PNVCz/PDMS) composite electrodes were prepared by electrochemical polymerization of NVCz monomer onto PDMS‐coated platinum (Pt) and glassy carbon (GC) electrode surfaces to investigate the influence of the insulating constituent, PDMS and process temperature on the capacitive performance of the coated layers. The electrochemical properties of the bilayer coatings were studied by electrochemical impedance spectroscopy and UV‐vis spectroelectrochemistry measurements. The low‐frequencies capacitance values of composite electrodes indicated that the capacitive behaviors of the composites decreased with increasing PDMS content (from 5.0 to 10.0; in wt/v%) in coating solutions at 25 °C, and with decreasing coating temperatures (from 25 °C to − 15 °C) of PDMS and PNVCz and, more resist PDMS/PNVCz layers formed. Copyright © 2011 John Wiley & Sons, Ltd.
Development of resonance‐enhanced multiphoton ionization SNMS for state‐selective detection of sputtered atoms under low‐energy ion irradiation
Authors: Kubota N. , Hayashi S.
Published: January 2011

An instrument for a sputtered neutral mass spectrometry with a quadrupole mass spectrometer (QMS) by resonance‐enhanced multiphton ionization method is developed to study sputtered neutrals emission phenomena under ion irradiation in a low‐energy region. We have prepared a pulsed primary ion beam and an ion counting system, and have optimized the operation parameter including a sample bias, energy analyzer voltages, pulsed timing of laser and ion beam, etc.

A yield ratio of the lowest‐lying excited state a5S2 to the ground state a7S3 for sputtered Cr atoms has been measured as a function of incident energy of Ar+ and O2+ down to 600 eV using a polycrystalline Cr sample. The yield ratio has become a constant value for the Ar+ incidence, while it has exponentially increased below 1 keV for the O2+ incidence. It is found that the internal energy distribution of sputtered Cr atoms has been significantly influenced by oxygen density at the surface. Copyright © 2011 John Wiley & Sons, Ltd.
Preparation and characterization of 5,10,15,20‐tetraphenylporphyrin Langmuir films for gas chemsensor applications
Authors: Mansur Herman S. , de Sales Nelício F. , Mansur Alexandra A. P.
Published: January 2011

In this work is reported the preparation and characterization of 5,10,15,20‐tetraphenylporphyrin (H2TPP) films at the water‐air interfaces. The surface pressure‐area isotherms (π‐A) and UV‐Vis spectroscopy were used to investigate the effect of the spreading methods and parameters on the porphyrin monolayer formation. Also, Langmuir‐Blodgett (LB) and Langmuir‐Schaefer (LS) films were deposited onto glass substrates in order to study the conformation changes in porphyrin molecular packing. Quartz crystal microbalance (QCM) was utilized as the active solid substrate for the development of the NO2 gas sensor based on the H2TPP molecular films. The results of π‐A curves have clearly shown the significant contribution of the preparation methods and processing parameters on the conformation of porphyrin molecular films. The UV‐Vis spectroscopy results using polarized absorption dichroism have indicated different molecular packing for porphyrin films deposited by LB and LS methods, with relative tilted angles of 50° ± 5° and 35° ± 5°, respectively. Moreover, the QCM response has given strong evidence that H2TPP porphyrin molecular films have performed as NO2 chemsensor. Copyright © 2011 John Wiley & Sons, Ltd.
Study of the structural and atomic diffusive properties of the ordered Cu3Au (110) surface
Authors: Wen Yan‐Ni , Zhang Yan , Zhang Jian‐Min , Xu Ke‐Wei
Published: January 2011

The structural properties, the formation and migration energies of a single vacancy migrating intralayer and interlayer in the CuAu‐terminated (110) surface of Cu3Au ordered alloy have been calculated and discussed by using the modified analytical embedded‐atom method (MAEAM) and molecular dynamics (MD) methods. The surface layer exhibits rippling that the Au atoms are raised above Cu atoms about 0.117 Å in the topmost layer. The displacements of the topmost two layers are comparatively larger, while the third layer relaxes slightly and there are no changes in the nether layers. From energy minimization, the vacancy is most likely to be formed in the first layer (1L), especially on the Au site. The surface vacancy shows the smallest formation energy compared to the interlayer and bulk vacancies, while the corresponding value converges after the fifth layer (5L). For Cu vacancy originally sited in the second layer (2L) and migrated intralayer and interlayer, the diffusion without causing the local disorder is the most favorable, and the vacancy tends to migrate to the topmost layer. In the topmost layer of the CuAu‐terminated (110) surface, the circularity path is preferred over the beeline path. Copyright © 2011 John Wiley & Sons, Ltd.
Controlled adhesion of Salmonella Typhimurium to poly(oligoethylene glycol methacrylate) grafts
Authors: Mrabet Bechir , Mejbri Aymen , Mahouche Samia , Gam‐Derouich Sarra , Turmine Mireille , Mechouet Mourad , Lang Philippe , Bakala Hilaire , Ladjimi Moncef , Bakhrouf Amina , Tougaard Sven , Chehimi Mohamed M.
Published: January 2011

Poly(oligoethylene glycol methacrylate), POEGMA, brushes were prepared by surface‐initiated atom transfer radical polymerization (SI‐ATRP) on gold‐coated silicon wafers. Prior to ATRP, the substrates were grafted by brominated aryl initiators via the electrochemical reduction of a noncommercial parent diazonium salt of the formula BF4−, +N2‐C6H4‐CH(CH3)Br. The diazonium‐modified gold plates (Au‐Br) served as macroinitiators for ATRP of OEGMA which resulted in hydrophilic surfaces (Au‐POEGMA) that could be used for two distinct objectives: (i) resistance to fouling by Salmonella Typhimurium; (ii) specific recognition of the same bacteria provided that the POEGMA grafts are activated by anti‐Salmonella. The Au‐POEGMA plates were characterized by XPS, polarization modulation‐infrared reflection‐absorption spectroscopy (PM‐IRRAS) and contact angle measurements. Both Beer‐Lambert equation and Tougaard's QUASES software indicated a POEGMA thickness that exceeds the critical ∼10 nm value necessary for obtaining a hydrophilic polymer with effective resistance to cell adhesion. The Au‐POEGMA slides were further activated by trichlorotriazine (TCT) in order to covalently bind anti‐Salmonella antibodies (AS). The antibody‐modified Au‐POEGMA specimens were found to specifically attach Salmonella Typhimurium bacteria. This work is another example of the diazonium salt/ATRP process to provide biomedical polymer surfaces. Copyright © 2011 John Wiley & Sons, Ltd.
Macroscopic single‐domain graphene sheet on Ni(111)
Authors: Odahara Genki , Otani Shigeki , Oshima Chuhei , Suzuki Masahiko , Yasue Tsuneo , Koshikawa Takanori
Published: January 2011

We observed in situ growth of a single graphene sheet on Ni(111) by low‐energy electron microscopy. The sheet was grown epitaxially beyond the steps on the substrate. The crystalline shapes of graphene islands were clearly seen; the straight edges of the island are crossed at either 60 or 120°, and the linear edges shifted perpendicular to the edge keeping the equilibrium shape. Graphene islands were united to form a single sheet without any grain boundaries and any wrinkles. The Ni substrate of several centimeters in size was covered with a single‐domain graphene sheet. Copyright © 2011 John Wiley & Sons, Ltd.
Multivariate meta‐analysis: Potential and promise
Authors: Jackson Dan , Riley Richard , White Ian R.
Published: January 2011

The multivariate random effects model is a generalization of the standard univariate model. Multivariate meta‐analysis is becoming more commonly used and the techniques and related computer software, although continually under development, are now in place. In order to raise awareness of the multivariate methods, and discuss their advantages and disadvantages, we organized a one day ‘Multivariate meta‐analysis’ event at the Royal Statistical Society. In addition to disseminating the most recent developments, we also received an abundance of comments, concerns, insights, critiques and encouragement. This article provides a balanced account of the day's discourse. By giving others the opportunity to respond to our assessment, we hope to ensure that the various view points and opinions are aired before multivariate meta‐analysis simply becomes another widely used de facto method without any proper consideration of it by the medical statistics community. We describe the areas of application that multivariate meta‐analysis has found, the methods available, the difficulties typically encountered and the arguments for and against the multivariate methods, using four representative but contrasting examples. We conclude that the multivariate methods can be useful, and in particular can provide estimates with better statistical properties, but also that these benefits come at the price of making more assumptions which do not result in better inference in every case. Although there is evidence that multivariate meta‐analysis has considerable potential, it must be even more carefully applied than its univariate counterpart in practice. Copyright © 2011 John Wiley & Sons, Ltd.
A stochastic multicriteria model for evidence‐based decision making in drug benefit‐risk analysis
Authors: Tervonen Tommi , van Valkenhoef Gert , Buskens Erik , Hillege Hans L. , Postmus Douwe
Published: January 2011

Drug benefit‐risk (BR) analysis is based on firm clinical evidence regarding various safety and efficacy outcomes. In this paper, we propose a new and more formal approach for constructing a supporting multi‐criteria model that fully takes into account the evidence on efficacy and adverse drug reactions. Our approach is based on the stochastic multi‐criteria acceptability analysis methodology, which allows us to compute the typical value judgments that support a decision, to quantify decision uncertainty, and to compute a comprehensive BR profile. We construct a multi‐criteria model for the therapeutic group of second‐generation antidepressants. We assess fluoxetine and venlafaxine together with placebo according to incidence of treatment response and three common adverse drug reactions by using data from a published study. Our model shows that there are clear trade‐offs among the treatment alternatives. Copyright © 2011 John Wiley & Sons, Ltd.
Mismatch handling for COTS selection: a case study
Authors: Mohamed Abdallah , Ruhe Guenther , Eberlein Armin
Published: January 2011

Using Commercial Off‐The‐Shelf (COTS) products to build software systems requires the evaluation of existing COTS products, the selection of the COTS that best fit system requirements, and the integration of the selected COTS into the system. During this process, it is inevitable to encounter two types of mismatches: (1) COTS mismatches, which are encountered during COTS selection between requirements and COTS features, due to an excess or shortage of COTS features, and (2) architectural mismatches, which arise when integrating multiple COTS products that do not fit well together. This paper focuses on the ‘COTS mismatch’ problem. The paper describes a real‐world case study of a single COTS selection with the aid of a method called MiHOS (Mismatch Handling for COTS Selection) to handle the COTS mismatches. MiHOS runs on top of existing COTS selection models in order to properly address COTS mismatches with limited resources. The case study was conducted in the e‐service domain. The goal was to validate MiHOS and to answer two key questions: (1) How useful is decision support during different phases in the process mismatch handling? And (2) what is the effort vs benefit of using MiHOS? The results are promising and illustrate the potential benefits of using MiHOS. Copyright © 2011 John Wiley & Sons, Ltd.
A Multigenerational View of Inequality
Authors: Mare Robert D.
Published: January 2011

The study of intergenerational mobility and most population research are governed by a two-generation (parent-to-offspring) view of intergenerational influence, to the neglect of the effects of grandparents and other ancestors and nonresident contemporary kin. While appropriate for some populations in some periods, this perspective may omit important sources of intergenerational continuity of family-based social inequality. Social institutions, which transcend individual lives, help support multigenerational influence, particularly at the extreme top and bottom of the social hierarchy, but to some extent in the middle as well. Multigenerational influence also works through demographic processes because families influence subsequent generations through differential fertility and survival, migration, and marriage patterns, as well as through direct transmission of socioeconomic rewards, statuses, and positions. Future research should attend more closely to multigenerational effects; to the tandem nature of demographic and socioeconomic reproduction; and to data, measures, and models that transcend coresident nuclear families.
ORGANIZATIONAL ANALYSIS OF THE SEED SECTOR OF RICE IN GUINEA: STAKEHOLDERS, PERCEPTION AND INSTITUTIONAL LINKAGES
Authors: OKRY FLORENT , VAN MELE PAUL , NUIJTEN EDWIN , STRUIK PAUL C. , MONGBO ROCH L.
Published: January 2011

This paper analyses the organization of the rice seed sector in Guinea with the overall objectives to assess how organizational settings affect seed supply to small-scale farmers and to suggest institutional changes that would favour seed service and uptake of varieties. Data were collected in Guinea, West Africa, using focus group discussions with extension workers, farmers, representatives of farmers’ associations, agro-input dealers, researchers and non-governmental organization (NGO) staff, and surveys of 91 rice farming households and 41 local seed dealers. Findings suggest that the current institutional settings and perceptions of stakeholders from the formal seed sector inhibit smallholder farmers’ access to seed. Seed interventions in the past two decades have mainly relied on the national extension system, the research institute, NGOs, farmers’ associations and contract seed producers to ensure seed delivery. Although local seed dealers play a central role in providing seed to farmers, governmental organizations operating in a linear model of formal seed sector development have so far ignored their role. We discuss the need to find common ground and alternative models of seed sector development. In particular we suggest the involvement of local seed dealers in seed development activities to better link the formal and the informal seed systems and improve smallholder farmers’ access to seed from the formal sector.
THE WATER RELATIONS AND IRRIGATION REQUIREMENTS OF COCONUT (Cocos nucifera): A REVIEW
Authors: CARR M. K. V.
Published: January 2011

The results of research on the water relations and irrigation needs of coconut are collated and summarized in an attempt to link fundamental studies on crop physiology to drought mitigation and irrigation practices. Background information on the centres of origin and production of coconut and on crop development processes is followed by reviews of plant water relations, crop water use and water productivity, including drought mitigation. The majority of the recent research published in the international literature has been conducted in Brazil, Kerala (South India) and Sri Lanka, and by CIRAD (France) in association with local research organizations in a number of countries, including the Ivory Coast. The unique vegetative structure of the palm (stem and leaves) together with the long interval between flower initiation and the harvesting of the mature fruit (44 months) mean that causal links between environmental factors (especially water) are difficult to establish. The stomata play an important role in controlling water loss, whilst the leaf water potential is a sensitive indicator of plant water status. Both stomatal conductance and leaf water potential are negatively correlated with the saturation deficit of the air. Although roots extend to depths >2 m and laterally >3 m, the density of roots is greatest in the top 0–1.0 m soil, and laterally within 1.0–1.5 m of the trunk. In general, dwarf cultivars are more susceptible to drought than tall ones. Methods of screening for drought tolerance based on physiological traits have been proposed. The best estimates of the actual water use (ETc) of mature palms indicate representative rates of about 3 mm d−1. Reported values for the crop coefficient (Kc) are variable but suggest that 0.7 is a reasonable estimate. Although the sensitivity of coconut to drought is well recognized, there is a limited amount of reliable data on actual yield responses to irrigation although annual yield increases (50%) of 20–40 nuts palm−1 (4–12 kg copra, cultivar dependent) have been reported. These are only realized in the third and subsequent years after the introduction of irrigation applied at a rate equivalent to about 2 mm d−1 (or 100 l palm−1 d−1) at intervals of up to one week. Irrigation increases female flower production and reduces premature nut fall. Basin irrigation, micro-sprinklers and drip irrigation are all suitable methods of applying water. Recommended methods of drought mitigation include the burial of husks in trenches adjacent to the plant, mulching and the application of common salt (chloride ions). An international approach to addressing the need for more information on water productivity is recommended.
SOIL WATER BALANCE AND GRAIN YIELD OF SORGHUM UNDER NO-TILL VERSUS CONVENTIONAL TILLAGE WITH SURFACE MULCH IN THE DERIVED SAVANNA ZONE OF SOUTHEASTERN NIGERIA
Authors: OBALUM S. E. , AMALU U. C. , OBI M. E. , WAKATSUKI T.
Published: January 2011

Over a decade after the forest-savanna transition zone of Nigeria was deemed suitable for production of sorghum (Sorghum bicolor), no research has been undertaken on the crop's tillage requirements in the southeastern part of the zone. This study evaluated the effects of tillage-mulch practices on soil moisture, water use (WU), grain yield and water use efficiency (WUE) of the crop in a Typic Paleustult (sandy loam) at Nsukka during 2006 and 2007 growing seasons. In a split-plot design, no-till (NT) and conventional tillage (CT) treatments were left bare (B) or covered with mulch (M) at 5 Mg ha−1. The ensuing treatments (NTB, NTM, CTB, and CTM) represented four tillage methods, which were replicated four times in a randomized complete block. In the monitored root zone, NTB and CTM significantly (p ≤ 0.05) enhanced the soil moisture status over NTM and CTB, but the main effects of the tillage and the mulch factors were not significant. The crop WU was uninfluenced by the treatments throughout the study. Although the grain yield showed higher values with NT than with CT, the differences were significant (p ≤ 0.05) only in 2007 that was marked with erratic rainfall and relatively low mean yield. Mulch significantly (p ≤ 0.05) enhanced the grain yield in 2006, with greater effect in CT than NT. On average, the mulch plots out-yielded their bare counterparts by about 26%. The tillage × mulch interaction was significant (p ≤ 0.01), and showed higher grain yields in NTB, NTM and CTM than in CTB. In the year-weighted average, yield increments in NTB, NTM and CTM over CTB were 53, 53 and 67% respectively, a pointer to the relevance of mulch with the CT but not the NT. Relative WU showed that the crop's water demand was met under all treatments. Hence, the yield reduction in the CTB was not due to water shortage. The WUE varied among the treatments in the same pattern as grain yield. In summary, NTB and CTM proved superior to NTM only in soil moisture status but to CTB in all measured parameters. From a socio-economic viewpoint, however, NTB would be preferable to CTM for growing sorghum in this area.
ADAPTABILITY OF IRRIGATED RICE TO TEMPERATURE CHANGE IN SAHELIAN ENVIRONMENTS
Authors: DE VRIES MICHIEL E. , LEFFELAAR PETER A. , SAKANÉ NOMÉ , BADO BOUBIÉ V. , GILLER KEN E.
Published: January 2011

To assess genotype adaptability to variable environments, we evaluated five irrigated rice genotypes, three new varieties, WAS161, a NERICA, IR32307 and ITA344, and two controls: Sahel 108, the most popular short-duration variety in the region, and IR64. In a field experiment conducted at two locations, Ndiaye and Fanaye, along the Senegal River, rice was sown on 15 consecutive dates at one month intervals starting in February 2006. Yield (0–12.2 t ha−1) and crop cycle duration (117–190 days) varied with sowing date, genotype and site. Rice yield was very sensitive to sowing date and the associated temperature regimes. Spikelet sterility due to cold stress (T < 20 °C) was observed when the crops were sown in August (Ndiaye), September (Ndiaye and Fanaye) and October (Ndiaye and Fanaye), and heat stress (T > 35 °C) resulted in spikelet sterility when sowing took place in April (Ndiaye and Fanaye) and May (Fanaye). For all experiments the source and sink balance was quantified and showed that yield was most limited by sink size when sowing between July and October. Variety WAS 161 was least affected by genotype × environment interactions, resulting in lower interactive principal component values. An increase in minimum temperature of 3 °C could decrease spikelet sterility from 100 to 45%. These changes in temperature are likely to force rice farmers in the Senegal River to adjust the cropping calendar, e.g. to delay planting or to use heat-tolerant genotypes.
Algebraic/transcendental disturbance growth behind a row of roughness elements
Authors: GOLDSTEIN M. E. , SESCU ADRIAN , DUCK PETER W. , CHOUDHARI MEELAN
Published: January 2011

This paper is a continuation of the work begun in Goldstein et al. (J. Fluid Mech., vol. 644, 2010, p. 123), who constructed an asymptotic high-Reynolds-number solution for the flow over a spanwise periodic array of relatively small roughness elements with (spanwise) separation and plan form dimensions of the order of the local boundary-layer thickness. While that paper concentrated on the linear problem, here the focus is on the case where the flow is nonlinear in the immediate vicinity of the roughness with emphasis on the intermediate wake region corresponding to streamwise distances that are large in comparison with the roughness dimension, but small in comparison with the distance between the roughness array and the leading edge. An analytical O(h2) asymptotic solution is obtained for the limiting case of a small roughness height parameter h. These weakly nonlinear results show that the spanwise variable component of the wall-pressure perturbation decays as x−5/3 ln x when x → ∞ (where x denotes the streamwise distance scaled on the roughness dimension), but the corresponding component of the streamwise velocity perturbation (i.e. the wake velocity) exhibits an O(x1/3 ln x) algebraic/transcendental growth in the main boundary layer. Numerical solutions for h = O(1) demonstrate that the wake velocity perturbation for the fully nonlinear case grows in the same manner as the weakly nonlinear prediction – which is considerably different from the strictly linear result obtained in Goldstein et al. (2010).
Drop fragmentation on impact
Authors: VILLERMAUX E. , BOSSA B.
Published: January 2011

We address the sequence of events accompanying the transition from an initially compact volume of liquid – a drop – into dispersed fragments when it impacts a solid surface. We describe the change of topology of the drop to a radially expanding sheet and discuss the reasons of its rim destabilization, responsible for the emergence of radial ligaments which ultimately fragment into smaller drops. The dynamics ruling the radius of the sheet, its stability and the resulting fragment drop size distribution are documented experimentally. The radius dynamics results from a simple balance between inertia of the initial drop and capillary restoring forces at the rim, with damping due to the continuous transfer of momentum from the sheet to the rim. The ligaments expelled from the rim originate from a Rayleigh–Taylor mechanism localized at the rim. The final drop size distribution in the spray is shown to be a linear superposition of gamma distributions characteristic of ligament breakup, leading generically to Bessel functions.
The wake of two side-by-side square cylinders
Authors: ALAM Md MAHBUB , ZHOU Y. , WANG X. W.
Published: January 2011

Aerodynamic interference between two cylinders involves most of the generic flow features associated with multiple structures, thus providing an excellent model for gaining physical insight into the wake of multiple cylindrical structures. This work aims to provide an experimental systematic study of the flow behind two side-by-side square cylinders. The square cylinder is a representative model for bluff bodies with sharp corners, characterized by a fixed flow separation point, which are distinct from those of continuous curvature with oscillating separation points, typically represented by the circular cylinder. Experiments were performed at a Reynolds number Re of 4.7 × 104 and a cylinder centre-to-centre spacing ratio T/d (d is the cylinder height) of 1.02–6.00. The flow was measured using different techniques, including hot wires, load cell, particle imaging velocimetry and laser-induced fluorescence flow visualization. Four distinct flow regimes and their corresponding T/d ranges are identified for the first time on the basis of the flow structure and the Strouhal number. Physical aspects in each regime, such as interference between shear layers, gap flow deflection and changeover, multiple flow modes, entrainment, recirculation bubble, vortex interactions and formation lengths, are investigated in detail and are connected to the characteristics of the time-averaged and fluctuating fluid forces. The flow displays a marked difference in many facets from that behind two side-by-side circular cylinders, which is linked to their distinct flow separation natures. A crucial role played by the gap flow and its passage geometry in contributing to the observed difference is also unveiled.
Oblique runup of non-breaking solitary waves on an inclined plane
Authors: PEDERSEN GEIR K.
Published: January 2011

When a wave of permanent form is obliquely incident on an inclined plane, the wave pattern becomes stationary in a frame of reference which moves along the shore. This enables a simplified mathematical description of the problem which is used herein as a basis for efficient and accurate numerical simulations. First, a nonlinear and weakly dispersive set of Boussinesq equations for the downstream evolution of such stationary patterns is derived. In the hydrostatic approximation, streamline-based Lagrangian versions of the evolution equations are developed for automatic tracing of the shoreline. Both equation sets are, in their present form, developed for non-breaking waves only. Finite difference models for both equation sets are designed. These methods are then coupled dynamically to obtain a single nonlinear model with dispersive wave propagation in finite depth and an accurate runup representation. The models are tested by runup of waves at normal incidence and comparison with a more general model for the refraction of a solitary wave on a slope. Finally, a set of runup computations for oblique solitary waves is performed and compared with estimates of oblique runup heights obtained from a combination of an analytic solution for normal incidence and optics. We find that the runup heights decrease in proportion to the square of the angle of incidence for angles up to 45°, for which the height is reduced by around 12% relative to that of normal incidence. In Appendix A, the validity of the downstream formulation is discussed in the light of solitary wave optics and wave jumps.
Flow of a viscous compressible fluid produced in a circular tube by an impulsive point source
Authors: FELDERHOF B. U. , OOMS G.
Published: January 2011

The flow of a viscous compressible fluid in a circular tube generated by a sudden impulse at a point on the axis is studied on the basis of the linearized Navier–Stokes equations. A no-slip boundary condition is assumed to hold on the wall of the tube. An efficient numerical scheme has been developed for the calculation of flow velocity and pressure disturbance as a function of position and time.
Dynamics of inertial particles in a turbulent von Kármán flow
Authors: VOLK R. , CALZAVARINI E. , LÉVÊQUE E. , PINTON J.-F.
Published: January 2011

We study the dynamics of neutrally buoyant particles with diameters varying in the range [1, 45] in Kolmogorov scale units (η) and Reynolds numbers based on Taylor scale (Reλ) between 590 and 1050. One component of the particle velocity is measured using an extended laser Doppler velocimetry at the centre of a von Kármán flow, and acceleration is derived by differentiation. We find that the particle acceleration variance decreases with increasing diameter with scaling close to (D/η)−2/3, in agreement with previous observations, and with a hint for an intermittent correction as suggested by arguments based on scaling of pressure spatial increments. The characteristic time of acceleration autocorrelation increases more strongly than previously reported in other experiments, and possibly varying linearly with D/η. Further analysis shows that the probability density functions of the acceleration have smaller wings for larger particles; their flatness decreases as well, as expected from the behaviour of pressure increments in turbulence when intermittency corrections are taken into account. We contrast our measurements with previous observations in wind-tunnel turbulent flows and numerical simulations.
The efficiency of pulsed-jet propulsion
Authors: LINDEN P. F.
Published: January 2011

Nature is often an inspiration for scientists and especially so in fluid dynamics. We observe and admire the beauty of birds and fish as they move through the air and water, and wonder how these forms of locomotion evolved and whether they are optimised for efficiency. A common feature of this locomotion is that the thrust is generated by the flapping of a wing or fin, creating an unsteady flow. Other less readily observed animals such as salps or squid eject a pulsed jet, raising the question of whether there is an advantage of this unsteady forcing over a steady jet. This is the question addressed by Ruiz, Whittlesey & Dabiri (J. Fluid Mech., this issue, vol. 668, 2011, pp. 5–32) who have carried out detailed flow and power-consumption measurements with a self-propelled vehicle in water. The vehicle has a novel propulsion mechanism that allows a comparison of the efficiency of a pulsed and steady jet to be compared. They show that significant increases in efficiency are possible with the pulsed jet, even allowing for the additional power needed to create the pulsed flow. They also show that vortex rings are produced by the unsteady jet and that the additional entrainment of ambient fluid into the ring and the higher pressure at the front of the ring are the cause of this increased efficiency.
Inertial effects on viscous fingering in the complex plane
Authors: HE ANDONG , BELMONTE ANDREW
Published: January 2011

We present a nonlinear unsteady Darcy's equation which includes inertial effects for flows in a porous medium or Hele-Shaw cell and discuss the conditions under which it reduces to the classical Darcy's law. In the absence of surface tension we derive a generalized Polubarinova–Galin equation in a circular geometry, using the method of conformal mapping. The linear stability of the base-flow state is examined by perturbing the corresponding conformal map. We show that inertia always has a tendency to stabilize the interface, regardless of whether a less viscous fluid is displacing a more viscous fluid or vice versa.