bluuebunny/crossref_metadata_2025 huggingface dataset:
Perspectives in AE—First System, Best System: The Proctored Examination
Authors: Pittman Von
Published: January 2015

The verification of student identity has always been a matter of concern in distance education programs. In short, how could a college know if the person performing the work was the same person receiving the credit? Colleges and universities have approached the problem in a variety of ways. Some have done virtually nothing, while others have begun to experiment with behavioral and biometric approaches, and still others have relied on physical proctors to oversee examinations. Due to recent congressional actions, the first approach is no longer an option. While the use of technological systems to verify identity and maintain course security seems promising, their application remains problematic. Only physical proctoring—the first approach to student identity verification—currently offers a reasonably effective, efficient, and affordable means of student identity verification.
Automatic generation of multiblock decompositions of surfaces
Authors: Fogg Harold J. , Armstrong Cecil G. , Robinson Trevor T.
Published: January 2015

Multiblock‐structured meshes have significant advantages over fully unstructured meshes in numerical simulation, but automatically generating these meshes is considerably more difficult. A method is described herein for automatically generating high‐quality multiblock decompositions of surfaces with boundaries. Controllability and flexibility are useful capabilities of the method. Additional alignment constraints for forcing the appearance of particular features in the decomposition can be easily handled. Also, adjustments are made according to input metric tensor fields that describe target element size properties. The general solution strategy is based around using a four‐way symmetry vector‐field, called a cross‐field, to describe the local mesh orientation on a triangulation of the surface. Initialisation is performed by propagating the boundary alignment constraints to the interior in a fast marching method. This is similar in a way to an advancing‐front or paving method but much more straightforward and flexible because mesh connectivity does not have to be managed in the cross‐field. Multiblock decompositions are generated by tracing the separatrices of the cross‐field to partition the surface into quadrilateral blocks with square corners. The final task of meshing the decomposition requires solving an integer programming problem for block division numbers. Copyright © 2015 John Wiley & Sons, Ltd.
TRAX: An approach for the time rational analysis of complex dynamic systems
Authors: Lecomte Christophe
Published: January 2015

This paper introduces a theoretical and algorithmic reduced model approach to efficiently evaluate time responses of complex dynamic systems. The proposed approach combines four main components: analytical expressions of the average of the system's transfer functions in the frequency domain, precise and convergent rational approximations of these exact expressions, exact evaluation of these approximations through model reduction in rational Krylov subspaces and semi‐analytical interpolation at just a few frequency points. The resulting algorithmic principles to evaluate the time response of a particular system are relatively straightforward: one first evaluates the response of the system with slight additional damping at a few frequencies and one then projects or reduces the system in the subspace spanned by these responses. The time response of the reduced model implicitly provides a precise evaluation of that of the original system. The properties of the reduced models and the precision of the proposed approach are studied, and applications on complex matrix systems are presented and discussed. While the theory and numerical algorithms are presented in a matrix context, they are also transposable in a continuous functional context. Copyright © 2015 John Wiley & Sons, Ltd.
A new hybrid boundary node method based on Taylor expansion and the Shepard interpolation method
Authors: Yan Fei , Lv Jia‐He , Feng Xia‐Ting , Pan Peng‐Zhi
Published: January 2015

A novel meshless method based on the Shepard and Taylor interpolation method (STIM) and the hybrid boundary node method (HBNM) is proposed. Based on the Shepard interpolation method and Taylor expansion, the STIM is developed to construct the shape function of the HBNM. In the STIM, the Shepard shape function is used as the basic function, which is the zero‐level shape function, and the high‐power basic functions are constructed through Taylor expansion. Four advantages of the STIM are the interpolation property, the arbitrarily high‐order consistency, the absence of inversion for the whole process of shape function construction, and the low computational expense. These properties are desirable in the implementation of meshless methods. By combining the STIM and the HBNM, a much more effective meshless method is proposed to solve the elasticity problems. Compared with the traditional HBNM, the STIM can improve accuracy because of the use of high‐power basic functions and can also improve the computational efficiency because there is no inversion for the shape function construction process. Numerical examples are given to demonstrate the accuracy and efficiency of the proposed method. Copyright © 2015 John Wiley & Sons, Ltd.
A node‐to‐node scheme with the aid of variable‐node elements for elasto‐plastic contact analysis
Authors: Jin Seungmin , Sohn Dongwoo , Lim Jae Hyuk , Im Seyoung
Published: January 2015

A strategy for a two‐dimensional contact analysis involving finite strain plasticity is developed with the aid of variable‐node elements. The variable‐node elements, in which nodes are added freely where they are needed, make it possible to transform the non‐matching meshes into matching meshes directly. They thereby facilitate an efficient analysis, maintaining node‐to‐node contact during the contact deformation. The contact patch test, wherein the contact patch is constructed out of variable‐node elements, is thus passed, and iterations for equilibrium solutions reach convergence faster in this scheme than in the conventional approach based on the node‐to‐surface contact. The effectiveness and accuracy of the proposed scheme are demonstrated through several numerical examples of elasto‐plastic contact analyses. Copyright © 2015 John Wiley & Sons, Ltd.
Brittle and ductile failure of rocks: Embedded discontinuity approach for representing mode I and mode II failure mechanisms
Authors: Nikolic M. , Ibrahimbegovic A. , Miscevic P.
Published: January 2015

In this work, we present a discrete beam lattice model with embedded discontinuities capable of simulating rock failure as a result of propagating cracks through rock mass. The developed model is a two‐dimensional (plane strain) microscale representation of rocks as a two‐phase heterogeneous material. Phase I is chosen for intact rock part, while phase II stands for pre‐existing microcracks and other defects. The proposed model relies on Timoshenko beam elements enhanced with additional kinematics to describe localized failure mechanisms. The model can properly take into account the fracture process zone with pre‐existing microcracks coalescence, along with localized failure modes, mode I of tensile opening and mode II of shear sliding. Furthermore, we give the very detailed presentation for two different approaches to capturing the evolution of modes I and II, and their interaction and combination. The first approach is to deal with modes I and II separately, where mode II can be activated but compression force may still be transferred through rock mass which is not yet completely damaged. The second approach is to represent both modes I and II being activated simultaneously at a point where complete failure is reached. A novel numerical procedure for dealing with two modes failure within framework of method of incompatible modes is presented in detail and validated by a set of numerical examples. Copyright © 2015 John Wiley & Sons, Ltd.
Coarse‐grained modeling and simulation of graphene sheets based on a discrete hyperelastic approach
Authors: Qian Dong , Zhou Zhong , Zheng Qingjin
Published: January 2015

A discrete hyperelastic model was developed in this paper for a single atomic layer of graphene structure that was originally planar. This model can be viewed as an extension to the well‐known continuum hyperelastic model. Based on the discrete nature of the atomic structure, the notion of discrete mapping and the concept of spatial secant were introduced. The spatial secant served as a deformation measure that provided a geometric exact mapping in the discrete sense between the atomistic and continuum representations. By incorporating a physics‐based interatomic potential, the corresponding discrete hyperelastic model was then established. After an introduction of the model, the computational implementation using the Galerkin finite element and/or meshfree method was outlined. The computational framework was then applied to study of the mechanics of graphene sheets. Extensive comparisons with full‐scale molecular mechanics simulations and experimental measurement were made to illustrate the robustness of this approach. Copyright © 2014 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.
Ph‐negative isolated myeloid sarcoma with NPM1 gene mutation in adolescent with Ph‐positive chronic myeloid leukemia in remission after treatment with allogeneic bone marrow transplantation and imatinib mesylate
Authors: Skalska‐Sadowska Jolanta , Januszkiewicz‐Lewandowska Danuta , Derwich Katarzyna , Pieczonka Anna , Samborska Magdalena , Wachowiak Jacek
Published: January 2015

Few patients in remission of Ph‐positive chronic myelogenous leukemia (CML) develop Ph‐negative MDS/AML, usually with clonal cytogenetic abnormalities. Isolated Ph‐negative myeloid sarcoma (MS) is presented here as a form of such disorder, different from Ph‐positive MS establishing CML relapse in blastic phase. We describe 11‐year‐old male who developed Ph‐negative isolated MS with NPM1 mutation, remaining in complete molecular remission of Ph‐positive chronic myeloid leukemia treated with allo‐HSCT in first chronic phase and with imatinib and donor lymphocyte infusion in molecular relapse. The possible mechanisms of the tumor formation are reviewed with stress on importance of comprehensive molecular/cytogenetic evaluations. Pediatr Blood Cancer 2015;62:1070–1071. © 2015 Wiley Periodicals, Inc.
New prospects for PV powered water desalination plants: case studies in Saudi Arabia
Authors: Fthenakis Vasilis , Atia Adam A. , Morin Olivier , Bkayrat Raed , Sinha Parikhit
Published: January 2015

Increased water demand and increased drought episodes in the Middle East and other regions necessitate an expansion in desalination projects and create a great market opportunity for photovoltaics (PV). PV‐powered desalination has previously been regarded as not being a cost‐competitive solution when compared with conventionally powered desalination; however, the decline in PV costs over the last few years has changed this outlook. This paper presents up‐to‐date performance and cost analysis of reverse osmosis (RO) desalination powered with PV connected to the Saudi Arabian grid. Reference cases include relatively small (i.e., producing 6550 m3 water per day) and large (i.e., 190 000 m3/day) desalination plants using seawater at a salinity of 40 000 ppm. We used data from a King Abdullah University for Science and Technology presentation and Hybrid Optimization Model for Electric Renewables 2.81 Energy Modeling Software (HOMER Energy LLC) in tandem with Desalination Economic Evaluation Program 4.0 (International Atomic Energy Agency) desalination software to analyze the techno‐economic feasibility of these plants. The first phase of our work entailed a comparison between dual‐axis high concentration PV (CPV) equipped with triple junction III/V solar cells and CdTe PV‐powered RO systems. The estimated levelized cost of electricity from CPV is $0.16/kWh, whereas that from CdTe PV is $0.10/kWh and $0.09/kWh for fixed‐tilt and one‐axis tracking systems, respectively. These costs are higher than the price of diesel‐based grid electricity in the region because diesel fuel is heavily subsidized in Saudi Arabia.

In the second phase, we determined the cost of producing desalinated water from the two RO plant sizes powered with CdTe PV. Assuming that the grid acts as zero‐loss storage, the total water cost ranges from a high cost of $1.39/m3 for the small RO plant coupled with latitude‐tilt, fixed PV to $0.85/m3 for the large RO plant coupled with optimally positioned one‐axis tracking systems; these PV power plants would displace 1 158 987 and 33 579 763 l of diesel per year, respectively. Furthermore, the corresponding savings in diesel subsidies enabled by PV are $1.5m and $43.2m per year. Applying these savings to the PV system calls for a levelized cost of electricity of $0.21/kWh, justifying a feed‐in‐tariff at this level. The avoided CO2 emissions by displacing diesel fuel would be 3115 and 90 241 tonnes per year for the small and large Photovoltaics Powered Reverse Osmosis Water Desalination (PV‐RO) plants, respectively. On the basis of the results of this study, we infer that there are great business prospects associated with large deployment of PV‐RO plants in the greater Middle East, and we estimate the reduction in regional CO2 emissions from such deployment. Copyright © 2015 John Wiley & Sons, Ltd.
Fabrication of highly ordered porous membranes of cellulose triacetate on ice substrates using breath figure method
Authors: Yu Bing , Cong Hailin , Li Zejing , Yuan Hua , Peng Qiaohong , Chi Ming , Yang Shujing , Yang Ruixia , Ranil Wickramasinghe S. , Tang Jianguo
Published: January 2015

Highly ordered porous membranes of cellulose triacetate (CTA) were prepared successfully on ice substrates using breath figure method. The pore size and structure of the membrane were modulated by changing CTA concentrations and substrate materials. As the CTA concentration in the casting solution increased, the pore size in the formed membrane decreased. The regularity of the membrane cast on the ice substrate was much better than that of the membrane cast on glass substrate, because the low temperature of ice substrate slowed down the evaporation rate of organic solvent, which offered enough time for condensed water droplets to self‐organize into an ordered array dispersed in the polymer solution before their coagulation. The ordered porous CTA membrane was not only used for microfiltration, but also used for fabrication of functional microstructures. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 552–558
Ca2+ and Mg2+ modulate conformational dynamics and stability of downstream regulatory element antagonist modulator
Authors: Pham Khoa , Dhulipala Gangadhar , Gonzalez Walter G. , Gerstman Bernard S. , Regmi Chola , Chapagain Prem P. , Miksovska Jaroslava
Published: January 2015

Downstream Regulatory Element Antagonist Modulator (DREAM) belongs to the family of neuronal calcium sensors (NCS) that transduce the intracellular changes in Ca2+ concentration into a variety of responses including gene expression, regulation of Kv channel activity, and calcium homeostasis. Despite the significant sequence and structural similarities with other NCS members, DREAM shows several features unique among NCS such as formation of a tetramer in the apo‐state, and interactions with various intracellular biomacromolecules including DNA, presenilin, Kv channels, and calmodulin. Here we use spectroscopic techniques in combination with molecular dynamics simulation to study conformational changes induced by Ca2+/Mg2+ association to DREAM. Our data indicate a minor impact of Ca2+ association on the overall structure of the N‐ and C‐terminal domains, although Ca2+ binding decreases the conformational heterogeneity as evident from the decrease in the fluorescence lifetime distribution in the Ca2+ bound forms of the protein. Time‐resolved fluorescence data indicate that Ca2+binding triggers a conformational transition that is characterized by more efficient quenching of Trp residue. The unfolding of DREAM occurs through an partially unfolded intermediate that is stabilized by Ca2+ association to EF‐hand 3 and EF‐hand 4. The native state is stabilized with respect to the partially unfolded state only in the presence of both Ca2+ and Mg2+ suggesting that, under physiological conditions, Ca2+ free DREAM exhibits a high conformational flexibility that may facilitate its physiological functions.
Additional disulfide bonds in insulin: Prediction, recombinant expression, receptor binding affinity, and stability
Authors: Vinther Tine N. , Pettersson Ingrid , Huus Kasper , Schlein Morten , Steensgaard Dorte B. , Sørensen Anders , Jensen Knud J. , Kjeldsen Thomas , Hubalek František
Published: January 2015

The structure of insulin, a glucose homeostasis‐controlling hormone, is highly conserved in all vertebrates and stabilized by three disulfide bonds. Recently, we designed a novel insulin analogue containing afourth disulfide bond located between positions A10‐B4. The N‐terminus of insulin's B‐chain is flexible and can adapt multiple conformations. We examined how well disulfide bond predictions algorithms could identify disulfide bonds in this region of insulin. In order to identify stable insulin analogues with additional disulfide bonds, which could be expressed, the Cβcut‐off distance had to be increased in many instances and single X‐ray structures as well as structures from MD simulations had to be used. The analogues that were identified by the algorithm without extensive adjustments of the prediction parameters were more thermally stable as assessed by DSC and CD and expressed in higher yields in comparison to analogues with additional disulfide bonds that were more difficult to predict. In contrast, addition of thefourth disulfide bond rendered all analogues resistant to fibrillation under stress conditions and all stable analogues bound to the insulin receptor with picomolar affinities. Thus activity and fibrillation propensity did not correlate with the results from the prediction algorithm.

Statement: A fourth disulfide bond has recently been introduced into insulin, a small two‐chain protein containing three native disulfide bonds. Here we show that a prediction algorithm predicts four additional four disulfide insulin analogues which could be expressed. Although the location of the additional disulfide bonds is only slightly shifted, this shift impacts both stability and activity of the resulting insulin analogues.
Energetic evaluation of binding modes in the C3d and Factor H (CCP 19‐20) complex
Authors: E. S. Harrison Reed , Gorham Ronald D. , Morikis Dimitrios
Published: January 2015

As a part of innate immunity, the complement system relies on activation of the alternative pathway (AP). While feed‐forward amplification generates an immune response towards foreign surfaces, the process requires regulation to prevent an immune response on the surface of host cells. Factor H (FH) is a complement protein secreted by native cells to negatively regulate the AP. In terms of structure, FH is composed of 20 complement‐control protein (CCP) modules that are structurally homologous but vary in composition and function. Mutations in these CCPs have been linked to states of autoimmunity. In particular, several mutations in CCP 19‐20 are correlated to atypical hemolytic uremic syndrome (aHUS). From crystallographic structures there are three putative binding sites of CCP 19‐20 on C3d. Since there has been some controversy over the primary mode of binding from experimental studies, we approach characterization of binding using computational methods. Specifically, we compare each binding mode in terms of electrostatic character, structural stability, dissociative and associative properties, and predicted free energy of binding. After a detailed investigation, we found two of the three binding sites to be similarly stable while varying in the number of contacts to C3d and in the energetic barrier to complex dissociation. These sites are likely physiologically relevant and may facilitate multivalent binding of FH CCP 19‐20 to C3b and either C3d or host glycosaminoglycans. We propose thermodynamically stable binding with modules 19 and 20, the latter driven by electrostatics, acting synergistically to increase the apparent affinity of FH for host surfaces.
Androgens regulate SMAD ubiquitination regulatory factor‐1 expression and prostate cancer cell invasion
Authors: Gang Xiaokun , Wang Guixia , Huang Haojie
Published: January 2015

BACKGROUND

Prostate cancer (PCa) is the most commonly diagnosed male cancer in the United States and is a hormone‐driven disease. Androgens have been recognized as a major promoter of PCa development and progression. However, the mechanism of androgen action in PCa, especially in PCa cell invasion and metastasis remains largely unclear. SMAD ubiquitination regulatory factor‐1 (SMURF1) is a C2‐WW‐HECT‐domain E3 ubiquitin ligase that plays important roles in cancer cell metastasis. Whether there is a relationship between androgens and SMURF1 expression is not known.

METHODS

The effect of androgens on the expression of SMURF1 in PCa cell lines was examined by Western blot analyses and reverse transcription‐polymerase chain reaction (RT‐PCR). Gene transfection was performed by electroporation to manipulate the expression levels of proteins studied. The binding of AR to the SMURF1 gene enhancer was determined by chromatin immunoprecipitation (ChIP) assay. Cell migration and invasion was measured by wound healing and Matrigel invasion assays, respectively.

RESULTS

We found that expression of SMURF1 is upregulated by androgens in PCa cell lines and that this effect of androgens is mediated through the androgen receptor (AR). We further showed that androgens regulate SMURF1 expression at transcriptional level and provided evidence that AR transcriptionally activates SMURF1 by binding to its enhancer that contains a canonical half androgen responsive element (ARE). Finally, we demonstrated that SMURF1 is important for androgen‐induced invasion of PCa cells.

CONCLUSIONS

We demonstrate for the first time that SMURF1 is a bona fide target gene of the AR. Our findings also suggest a potential role of SMURF1 in PCa metastasis. Prostate 75: 561–572, 2015. © 2015 Wiley Periodicals, Inc.
The complexity and structural diversity of ant venom peptidomes is revealed by mass spectrometry profiling
Authors: Touchard Axel , Koh Jennifer M. S. , Aili Samira R. , Dejean Alain , Nicholson Graham M. , Orivel Jérôme , Escoubas Pierre
Published: January 2015

Rationale

Compared with other animal venoms, ant venoms remain little explored. Ants have evolved complex venoms to rapidly immobilize arthropod prey and to protect their colonies from predators and pathogens. Many ants have retained peptide‐rich venoms that are similar to those of other arthropod groups.

Methods

With the goal of conducting a broad and comprehensive survey of ant venom peptide diversity, we investigated the peptide composition of venoms from 82 stinging ant species from nine subfamilies using matrix‐assisted laser desorption/ionisation time‐of‐flight mass spectrometry (MALDI‐TOFMS). We also conducted an in‐depth investigation of eight venoms using reversed‐phase high‐performance liquid chromatography (RP‐HPLC) separation coupled with offline MALDI‐TOFMS.

Results

Our results reveal that the peptide compositions of ant venom peptidomes from both poneroid and formicoid ant clades comprise hundreds of small peptides (<4 kDa), while large peptides (>4 kDa) are also present in the venom of formicoids. Chemical reduction revealed the presence of disulfide‐linked peptides in most ant subfamilies, including peptides structured by one, two or three disulfide bonds as well as dimeric peptides reticulated by three disulfide bonds.

Conclusions

The biochemical complexity of ant venoms, associated with an enormous ecological and taxonomic diversity, suggests that stinging ant venoms constitute a promising source of bioactive molecules that could be exploited in the search for novel drug and biopesticide leads. Copyright © 2015 John Wiley & Sons, Ltd.
Schlieren visualization of fluid dynamics effects in direct analysis in real time mass spectrometry
Authors: Curtis Matthew , Keelor Joel D. , Jones Christina M. , Pittman Jennifer J. , Jones Patrick R. , Sparkman O. David , Fernández Facundo M.
Published: January 2015

Rationale

The success of ambient analysis using plasma‐based ion sources depends heavily on fluid dynamics and mass transport efficiency in the sample region. To help characterize the influence of these determining factors, visualization of the gas flow profile for a Direct Analysis in Real Time (DART) ion source at the mass spectrometer atmospheric pressure (AP) interface was performed using the Schlieren technique.

Methods

The DART helium flow pattern was imaged in model systems incorporating different interface designs, i.e. skimmer or capillary inlet, and for sampling strategies using several types of traditional DART sample probes including a glass capillary, swab, and drug tablet. Notably, Schlieren experiments were conducted on instruments equipped with the gas‐ion separator tube (GIST) adapter and Vapur® pump, and on setups featuring the transmission mode (TM) DART module used in standard practice.

Results

DART sources were seen to expel a collimated, highly laminar helium stream across interface distances up to ~8 cm. The helium stream was robust to the influence of gas temperature (50–500 °C) and flow rate (≤3.5 L min–1), but considerable DART gas deflection or full disruption was observed in each sampling scenario. The severity of the flow disturbance depended on probe size and placement, the GIST/Vapur® settings, or counter‐current gas movements present at the interface.

Conclusions

The real‐time Schlieren visualizations introduced in this work provide new insight on the fluid dynamics within the DART‐MS sample gap while also helping to identify those experimental parameters requiring optimization for improved transmission. Copyright © 2015 John Wiley & Sons, Ltd.
Analysis of neonicotinoids from plant material by desorption atmospheric pressure photoionization‐mass spectrometry
Authors: Vaikkinen Anu , Schmidt Henning S. , Kiiski Iiro , Rämö Sari , Hakala Kati , Haapala Markus , Kostiainen Risto , Kauppila Tiina J.
Published: January 2015

Rationale

Neonicotinoids are widely used insecticides which have been shown to affect the memory and learning abilities of honey bees, and are suspected to play a part in the unexplainable, large‐scale loss of honey bee colonies. Fast methods, such as ambient mass spectrometry (MS), for their analysis from a variety of matrices are necessary to control the use of forbidden products and study the spreading of insecticides in nature.

Methods

The feasibilities of two ambient MS methods, desorption electrospray ionization (DESI) and desorption atmospheric pressure photoionization (DAPPI), for the analysis of five most used neonicotinoid compounds, thiacloprid, acetamiprid, clothianidin, imidacloprid and thiamethoxam, were tested. In addition, DAPPI was used to analyze fresh rose leaves treated with commercially available thiacloprid insecticide and dried and powdered turnip rape flowers, which had been collected from a field treated with thiacloprid‐containing insecticide.

Results

DAPPI was found to be more sensitive than DESI, with 2–11 times better signal‐to‐noise ratios, and limits of detection at 0.4–5.0 fmol for the standard compounds. DAPPI was able to detect thiacloprid from the rose leaves even 2.5 months after the treatment and from the turnip rape flower samples collected from a field. The analysis of plant material by DAPPI did not require extraction or other sample preparation.

Conclusions

DAPPI was found to be suitable for the fast and direct qualitative analysis of thiacloprid neonicotinoid from plant samples. It shows promise as a fast tool for screening of forbidden insecticides, or studying the distribution of insecticides in nature. Copyright © 2015 John Wiley & Sons, Ltd.
SAKE: scalable authenticated key exchange for mobile e‐health networks
Authors: Liu Weiran , Liu Jianwei , Wu Qianhong , Susilo Willy , Deng Hua , Qin Bo
Published: January 2015

Mobile e‐Health Network (MHN) is an emerging cloud‐aided networking application across the entire range of functions involved in e‐Health systems. It is important to establish secure channels between users because the data transmitted in MHNs are private, for example, personal electronic healthcare records. It is of great significance to employ key management mechanism and encrypt the data before transmitting in MHNs. However, secure key management is challenging in MHNs because of its highly dynamic and large‐scale nature. In this paper, we first model MHNs and formalize a hierarchical network architecture mirroring the administrative hierarchy and dynamic autonomy in MHNs in the real world. We next present a virtual MHN architecture with only three levels yet suitable to realistic MHNs with arbitrary hierarchical levels. By exploiting the virtual architecture, we propose an efficient authenticated key exchange framework to secure MHNs. We realize a scalable authenticated key exchange scheme with a dedicated variant of a recent hierarchical identity‐based signature and the well‐known Diffie–Hellman key exchange protocol. Theoretical analyses and experimental results show that scalable authenticated key exchange is secure and scalable and hence is practical to secure MHNs. Copyright © 2015 John Wiley & Sons, Ltd.
Sensitivity of regression calibration to non‐perfect validation data with application to the Norwegian Women and Cancer Study
Authors: Buonaccorsi John P. , Dalen Ingvild , Laake Petter , Hjartåker Anette , Engeset Dagrun , Thoresen Magne
Published: January 2015

Measurement error occurs when we observe error‐prone surrogates, rather than true values. It is common in observational studies and especially so in epidemiology, in nutritional epidemiology in particular. Correcting for measurement error has become common, and regression calibration is the most popular way to account for measurement error in continuous covariates. We consider its use in the context where there are validation data, which are used to calibrate the true values given the observed covariates. We allow for the case that the true value itself may not be observed in the validation data, but instead, a so‐called reference measure is observed. The regression calibration method relies on certain assumptions.This paper examines possible biases in regression calibration estimators when some of these assumptions are violated. More specifically, we allow for the fact that (i) the reference measure may not necessarily be an ‘alloyed gold standard’ (i.e., unbiased) for the true value; (ii) there may be correlated random subject effects contributing to the surrogate and reference measures in the validation data; and (iii) the calibration model itself may not be the same in the validation study as in the main study; that is, it is not transportable. We expand on previous work to provide a general result, which characterizes potential bias in the regression calibration estimators as a result of any combination of the violations aforementioned. We then illustrate some of the general results with data from the Norwegian Women and Cancer Study. Copyright © 2015 John Wiley & Sons, Ltd.
Surrogates of protection in repeated low‐dose challenge experiments
Authors: Long Dustin M. , Hudgens Michael G. , Wu Chih‐Da
Published: January 2015

A critical step toward developing a successful vaccine to control the human immunodeficiency virus pandemic entails evaluation of vaccine candidates in non‐human primates (NHPs). Historically, these studies have usually entailed challenges (i.e., exposures) with very high doses of a simian version of human immunodeficiency virus, resulting in infection of all NHPs in the experiment after a single challenge. More recently, researchers have begun to conduct repeated low‐dose challenge (RLC) studies in NHPs that are believed to more closely mimic typical exposure in natural human transmission settings. One objective of RLC studies is to assess whether measured immune responses to vaccination can serve as surrogate endpoints for the primary endpoint of interest, namely infection. In this paper, different designs of RLC studies for assessing a binary surrogate of protection are considered. Copyright © 2015 John Wiley & Sons, Ltd.
Surface Plasmon‐Enhanced Photodetection in Few Layer MoS2 Phototransistors with Au Nanostructure Arrays
Authors: Miao Jinshui , Hu Weida , Jing Youliang , Luo Wenjin , Liao Lei , Pan Anlian , Wu Shiwei , Cheng Jingxin , Chen Xiaoshuang , Lu Wei
Published: January 2015

2D Molybdenum disulfide (MoS2) is a promising candidate material for high‐speed and flexible optoelectronic devices, but only with low photoresponsivity. Here, a large enhancement of photocurrent response is obtained by coupling few‐layer MoS2 with Au plasmonic nanostructure arrays. Au nanoparticles or nanoplates placed onto few‐layer MoS2 surface can enhance the local optical field in the MoS2 layer, due to the localized surface plasmon (LSP) resonance. After depositing 4 nm thick Au nanoparticles sparsely onto few‐layer MoS2 phototransistors, a doubled increase in the photocurrent response is observed. The photocurrent of few‐layer MoS2 phototransistors exhibits a threefold enhancement with periodic Au nanoarrays. The simulated optical field distribution confirms that light can be trapped and enhanced near the Au nanoplates. These findings offer an avenue for practical applications of high performance MoS2‐based optoelectronic devices or systems in the future.
Delineating Foreign Market Potential: A Tool for International Market Selection
Authors: Ozturk Ayse , Joiner Eric , Cavusgil S. Tamer
Published: January 2015

International expansion is becoming more imperative in today's marketplace. However, determining which markets best suit a specific company is not a straightforward task. This study tackles the question of how managers should go about identifying, evaluating, and selecting foreign markets. For this purpose, we propose a practical, flexible, and forward‐looking three‐stage template for assessing foreign market opportunities and identifying the most promising international markets. The three stages include determining country responsiveness for a specific industry, estimating future industry growth, and incorporating an industry‐relevant aggregate measure. The study illustrates the tool for three companies from various industries and discusses the implications. The proposed tool offers insights on crucial dimensions for the industry‐specific market potential, and assists managers in identifying favorable foreign markets. This study also addresses the gap in the international market selection literature by developing a new empirical tool for foreign market analysis and selection using longitudinal secondary data. © 2015 Wiley Periodicals, Inc.
Re: Correlation between histological signs of placental underperfusion and perinatal morbidity in late‐onset small‐for‐gestational‐age fetuses. M. Parra‐Saavedra, S. Simeone, S. Triunfo, F. Crovetto, F. Botet, A. Nadal, E. Gratacos and F. Figueras. Ultrasound Obstet Gynecol 2015; 45: 149–155
Authors: Morales‐Roselló J.
Published: January 2015

Linked Comment: Ultrasound Obstet Gynecol 2015; 45: 149–155
Chlorination of poly(vinyl chloride) model compounds in radical‐complexing solvents
Authors: Ge Xianlong , Starnes William H.
Published: January 2015

A potential route to the preparation of poly(1,2‐dichloroethylene) by the selective chlorination of poly(vinyl chloride) (PVC) was explored. During free‐radical chlorinations with Cl2, certain solvents play the very important role of forming complexes with the free chlorine atom that lead to changes in the pattern of chlorine substitution. In our work, the photochlorination of three model compounds for PVC, namely, 2,4‐dichloropentane, 3‐chloropentane, and 4‐chloroheptane, was carried out with molecular chlorine in the absence or presence of complexing solvents. The effects of these solvents on the chlorination selectivity were determined. During the conventional chlorination of sec‐alkyl chlorides with molecular chlorine, bridged‐radical intermediates are believed to be involved. They lead to vicinal dichlorides as the major products. However, we found that complexing solvents significantly increased the yields of geminal dichlorides instead. Such solvents also are well known to decrease reactivity in free‐radical chlorinations with Cl2. Thus, for both of these reasons, the chlorination of PVC with Cl2 in complexing solvents is unlikely to be useful for the preparation of poly(1,2‐dichloroethylene). J. VINYL ADDIT. TECHNOL., 22:405–409, 2016. © 2015 Society of Plastics Engineers
Effect of zinc oxide on the viscosity and adhesion property of epoxidized natural rubber/acrylonitrile‐butadiene rubber‐based pressure‐sensitive adhesives
Authors: Poh B.T. , Suid N.H.
Published: January 2015

Viscosity, loop tack, peel strength, and shear strength of epoxidized natural rubber (ENR 50)/acrylonitrile‐butadiene rubber (NBR)–based pressure‐sensitive adhesive were studied in the presence of zinc oxide. The zinc oxide concentration was varied from 10 to 50 parts by weight per hundred parts of rubber (phr). Coumarone–indene resin with loading of 40 phr was chosen as the tackifier resin. Toluene and polyethylene terephthalate were used as the solvent and coating substrate, respectively, throughout the experiment. The adhesive was coated on the substrate by using a SHEEN hand coater. Viscosity of the adhesive was determined by a Brookfield Viscometer, whereas the loop tack, peel strength, and shear strength were measured by a Lloyd Adhesion Tester operating at 30 cm/min. Results indicate that viscosity increases with zinc oxide concentration owing to the concentration effect. Loop tack and peel strength pass through a maximum value at 20 phr of zinc oxide concentration. This observation is associated with the effect of varying degrees of wettability of the adhesive on the substrate. Shear strength, however, increases steadily with increasing zinc oxide loading owing to the steady increase in cohesive strength. In all cases, the adhesion properties of adhesives increase with increasing coating thicknesses. J. VINYL ADDIT. TECHNOL., 22:410–414, 2016. © 2015 Society of Plastics Engineers
Characterization of poly(vinyl chloride) compounds containing different levels of starch
Authors: Rosa D.S. , Rios A. R. , Viana H.M. , Tavares M.I.B.
Published: January 2015

Despite poly(vinyl chloride) (PVC) being one of the most useful materials available to the fabricator, its inadequate disposal has contributed to strong noneconomic issues based on the allegedly evil effects of chlorine. In this study, we examined the influence of adding starch, a biodegradable bioplastics, to mixtures of PVC plasticized with di(2‐ethylhexyl) adipate (which is susceptible to fungal attack). PVC and its mixtures were assessed by mechanical properties, differential scanning calorimetry, Fourier‐transform infrared spectroscopy, low‐field nuclear magnetic resonance, thermogravimetric analysis, optical microscopy, and degradation in simulated soil. Increasing the amount of starch in the mixtures resulted in greater material stiffness, with a reduction in tensile strength at break (σ) and elongation at break (ɛ). Fourier‐transform infrared spectroscopy and nuclear magnetic resonance showed that there was limited interfacial interaction between components of the PVC mixtures, which agreed with slight phase separation (breakage of the interfaces) and the decrease in the values of σ and ɛ for the mixtures. Samples containing a larger content of starch showed little weight loss after 2, 4, and 6 months in simulated soil, possibly because the starch was encapsulated by the PVC resin. J. VINYL ADDIT. TECHNOL., 22:396–404, 2016. © 2015 Society of Plastics Engineers
Dissecting the roles of TRBP and PACT in double‐stranded RNA recognition and processing of noncoding RNAs
Authors: Heyam Alex , Lagos Dimitris , Plevin Michael
Published: January 2015

HIV TAR RNA‐binding protein (TRBP) and Protein Activator of PKR (PACT) are double‐stranded (ds) RNA‐binding proteins that participate in both small regulatory RNA biogenesis and the response to viral dsRNA. Despite considerable progress toward understanding the structure–function relationship of TRBP and PACT, their specific roles in these seemingly distinct cellular pathways remain unclear. Both proteins are composed of three copies of the double‐stranded RNA‐binding domain, two of which interact with dsRNA, while the C‐terminal copy mediates protein–protein interactions. PACT and TRBP are found in a complex with the endonuclease Dicer and facilitate processing of immature microRNAs. Their precise contribution to the Dicing step has not yet been defined: possibilities include precursor recruitment, rearrangement of dsRNA within the complex, loading the processed microRNA into the RNA‐induced silencing complex, and distinguishing different classes of small dsRNA. TRBP and PACT also interact with the viral dsRNA sensors retinoic acid‐inducible gene I (RIG‐I) and double‐stranded RNA‐activated protein kinase (PKR). Current models suggest that PACT enables RIG‐I to detect a wider range of viral dsRNAs, while TRBP and PACT exert opposing regulatory effects on PKR. Here, the evidence that implicates TRBP and PACT in regulatory RNA processing and viral dsRNA sensing is reviewed and discussed in the context of their molecular structure. The broader implications of a link between microRNA biogenesis and the innate antiviral response pathway are also considered. WIREs RNA 2015, 6:271–289. doi: 10.1002/wrna.1272

This article is categorized under:

RNA Interactions with Proteins and Other Molecules > Protein–RNA Interactions: Functional Implications

RNA Turnover and Surveillance > Turnover/Surveillance Mechanisms

Regulatory RNAs/RNAi/Riboswitches > Biogenesis of Effector Small RNAs
Functional roles of alternative splicing factors in human disease
Authors: Cieply Benjamin , Carstens Russ P.
Published: January 2015

Alternative splicing (AS) is an important mechanism used to generate greater transcriptomic and proteomic diversity from a finite genome. Nearly all human gene transcripts are alternatively spliced and can produce protein isoforms with divergent and even antagonistic properties that impact cell functions. Many AS events are tightly regulated in a cell‐type or tissue‐specific manner, and at different developmental stages. AS is regulated by RNA‐binding proteins, including cell‐ or tissue‐specific splicing factors. In the past few years, technological advances have defined genome‐wide programs of AS regulated by increasing numbers of splicing factors. These splicing regulatory networks (SRNs) consist of transcripts that encode proteins that function in coordinated and related processes that impact the development and phenotypes of different cell types. As such, it is increasingly recognized that disruption of normal programs of splicing regulated by different splicing factors can lead to human diseases. We will summarize examples of diseases in which altered expression or function of splicing regulatory proteins has been implicated in human disease pathophysiology. As the role of AS continues to be unveiled in human disease and disease risk, it is hoped that further investigations into the functions of numerous splicing factors and their regulated targets will enable the development of novel therapies that are directed at specific AS events as well as the biological pathways they impact. WIREs RNA 2015, 6:311–326. doi: 10.1002/wrna.1276

This article is categorized under:

RNA Processing > Splicing Mechanisms

RNA Processing > Splicing Regulation/Alternative Splicing

RNA in Disease and Development > RNA in Disease
Preparation of Aluminum Hydrides with Chelating Anilido‐Imine Ligands by Addition of an Al–H Bond to a C=N Bond
Authors: Wang Weiwei , Yang Zhi , Ma Xiaoli , Roesky Herbert W. , Ju Yingxin , Hao Pengfei
Published: January 2015

Reacting o‐C6H4F(CH = NC6H3iPr2‐2,6) (L) with H3Al·NMe3 resulted in the aluminum dihydride with coordinated NMe3 of composition [o‐C6H4F(CH2NC6H3iPr2‐2,6)]AlH2(NMe3)(1). Furthermore, the aluminum monohydride [o‐C6H4N(C6H3iPr2‐2,6)(CH2NC6H3iPr2‐2,6)]AlH(NMe3) (2) was prepared by treatment of the anilido‐imine ligand o‐C6H4N(C6H3iPr2‐2,6)(CH = NC6H3iPr2‐2,6) (L*) with H3Al·NMe3 in high yield. The formations of the two complexes both involve aluminum hydride addition to the C=N double bond. Compounds 1 and 2 were characterized by 1H NMR and IR spectroscopic, elementary analysis, and single‐crystal X‐ray diffraction studies.
Oxidative Addition of Diethylchalcogenanes to Lappert's Germylene and Stannylene
Authors: Bendt Georg , Lapsien Silvia , Steiniger Phillip , Bläser Dieter , Wölper Christoph , Schulz Stephan
Published: January 2015

Oxidative addition of diethyldichalcogenanes Et2E2 (E = S, Se, Te) to bis[bis(trimethylsilyl]amido]germylene and ‐stannylene M[N(SiMe3)2]2 (M = Ge, Sn) proceed with formation of the corresponding bis(ethylchalcogenato)germanes (Me3Si)2N)2Ge(EEt)2 [E = S (1), Se (2), Te (3)] and ‐stannanes (Me3Si)2N)2Sn(EEt)2 [E = S (4), Se (5), Te (6)]. The solid state structures of 1–6 were determined by single‐crystal X‐ray diffraction.
Risk Factors for Conversion of Laparoscopic Colorectal Surgery to Open Surgery: Does Conversion Worsen Outcome?
Authors: Masoomi Hossein , Moghadamyeghaneh Zhobin , Mills Steven , Carmichael Joseph C. , Pigazzi Alessio , Stamos Michael J.
Published: January 2015

Introduction

The utilization of laparoscopy in colorectal surgery is increasing. However, conversion to open surgery remains relatively high.

Objective

We evaluated (1) conversion rates in laparoscopic colorectal surgery; (2) the outcomes of converted cases compared with successful laparoscopic and open colorectal operations; (3) predictive risk factors of conversion of laparoscopic colorectal surgery to open surgery.

Methods

Using the National Inpatient Sample database, we examined the clinical data of patients who underwent colon and rectal resection from 2009 to 2010. Multivariate regression analysis was performed to identify factors predictive for conversion of laparoscopic to open operation.

Results

A total of 207,311 patients underwent intended laparoscopic colorectal resection during this period. The conversion rate was 16.6 %. Considering resection type and pathology, the highest conversion rates were observed in proctectomy (31.4 %) and Crohn’s disease (20.2 %). Using multivariate regression analysis, Crohn’s disease (adjusted odds ratio [AOR], 2.80), prior abdominal surgery (AOR, 2.45), proctectomy (AOR, 2.42), malignant pathology (AOR, 1.90), emergent surgery (AOR, 1.82), obesity (AOR, 1.63), and ulcerative colitis (AOR, 1.60) significantly impacted the risk of conversion. Compared with patients who were successfully completed laparoscopically, converted patients had a significantly higher complication rate (laparoscopic: 23 %; vs. converted: 35.2 % vs. open: 35.3 %), a higher in‐hospital mortality rate (laparoscopic: 0.5 %; vs. converted: 0.6 %; vs. open: 1.7 %) and a longer mean hospital stay (laparoscopic: 5.4 days; vs. converted: 8.1 days; vs. open: 8.4 days); however, converted patients had better outcomes compared with the open group.

Conclusions

The conversion rate in colorectal surgery was 16.6 %. Converted patients had significantly higher rates of morbidity and mortality compared to successfully completed laparoscopic cases, although lower than open cases. Crohn’s disease, prior abdominal surgery, and proctectomy are the strongest predictors for conversion of laparoscopic to open in colorectal operations.