bluuebunny/crossref_metadata_2025 huggingface dataset:
Dual compensation strategy for real‐time hybrid testing
Authors: Chen Pei‐Ching , Tsai Keh‐Chyuan
Published: April 2012

Real‐time hybrid testing is an experimental technique for evaluating the dynamic responses of structural systems under seismic loading. Servo‐hydraulic actuators, by nature, induce inevitable time delay between the command and the achieved displacements. This delay would lead to incorrect test results and even cause instability of the system; therefore, delay compensation is critical for stability and accuracy of hybrid simulations of structural dynamic response. In this paper, a dual delay compensation strategy is proposed by a combination of a phase lead compensator and a restoring force compensator. An outer‐loop feed‐forward phase lead compensator is derived by introducing the inverse model in the z domain. The adaptive law based on the gradient algorithm is used to estimate the system delay in the format of parametric model during the test. It is shown mathematically that the parameter in the delay estimator is guaranteed to converge. The restoring force compensator is adopted to improve the accuracy of experimental results especially when the structure is subjected to high frequency excitations. Finally, analytical simulations of an inelastic SDOF structure are conducted to investigate the feasibility of the proposed strategy. The accuracy of the dual compensation strategy is demonstrated through several shaking table tests. Copyright © 2012 John Wiley & Sons, Ltd.
A revised approach to discriminating sediment transport histories in glacigenic sediments in a temperate alpine environment: a case study from Fox Glacier, New Zealand
Authors: Brook Martin S. , Lukas Sven
Published: April 2012

Clast shape measurements have developed into a standard method for reconstructing the transport histories of sediments in glacial environments. The majority of studies use the ‘RA‐C40’ covariance approach, with some researchers routinely including clasts of varying lithologies within their samples. The corollary is that variable lithological properties may control clast form and roundness, rather than debris‐transport mechanisms. Despite this, the role of lithology on clast shape in glacial environments has rarely been analysed. Furthermore, some studies have reported difficulties in using the RA‐C40 co‐variance plot in discriminating clasts that have undergone subglacial transport, and clasts that have been modified by fluvial activity. Results from a glacierized valley in a temperate alpine setting indicate that detailed analysis of clast shape where samples are of uniform lithology, although time consuming, is a useful tool in the investigation of deposits in glaciated environments. Copyright © 2012 John Wiley & Sons, Ltd.
Cochrane review on ‘Statins for the treatment of dementia’
Authors: McGuinness Bernadette , O'Hare John , Craig David , Bullock Roger , Malouf Reem , Passmore Peter
Published: April 2012

Objectives

This review aimed to assess the clinical efficacy and tolerability of statins in the treatment of dementia.

Methods

We searched the Specialized Register of the Cochrane Dementia and Cognitive Improvement Group, The Cochrane Library, MEDLINE, EMBASE, PsycINFO, CINAHL and LILACS, as well as many trials registries and grey literature sources (27 October 2008). Double‐blind, randomized controlled trials of statins given for at least 6 months in people with a diagnosis of dementia were included. Two independent authors extracted and assessed data independently against the inclusion criteria. Data were pooled where appropriate and entered into a meta‐analysis.

Results

Three studies were identified (748 participants, age range 50–90 years). All patients had a diagnosis of probable or possible Alzheimer's disease according to standard criteria, and most patients were established on a cholinesterase inhibitor. Change in Alzheimer's Disease Assessment Scale cognitive subscale from baseline was a primary outcome in three studies; when data were pooled, statins did not provide any beneficial effect in this cognitive measure (mean difference −1.12; 95% confidence interval −3.99, 1.75; p = 0.44). All studies provided a change in Mini‐Mental State Examination from baseline; there was no significant benefit from statins in this cognitive measure when the data were pooled (mean difference −1.53; 95% confidence interval −3.28; 0.21, p = 0.08). There were no studies identified assessing the role of statins in treatment of vascular dementia. There was no evidence that statins were detrimental to cognition.

Conclusions

There is insufficient evidence to recommend statins for the treatment of dementia. Copyright © 2012 John Wiley & Sons, Ltd.
Nanog regulates self-renewal of cancer stem cells through the insulin-like growth factor pathway in human hepatocellular carcinoma
Authors: Shan Juanjuan , Shen Junjie , Liu Limei , Xia Feng , Xu Chuan , Duan Guangjie , Xu Yanmin , Ma Qinghua , Yang Zhi , Zhang Qianzhen , Ma Leina , Liu Jia , Xu Senlin , Yan Xiaochu , Bie Ping , Cui Youhong , Bian Xiu-wu , Qian Cheng
Published: April 2012

Hepatocellular carcinoma (HCC) exhibits cellular heterogeneity and embryonic stem-cell–related genes are preferentially overexpressed in a fraction of cancer cells of poorly differentiated tumors. However, it is not known whether or how these cancer cells contribute to tumor initiation and progression. Here, our data showed that increased expression of pluripotency transcription factor Nanog in cancer cells correlates with a worse clinical outcome in HCC. Using the Nanog promoter as a reporter system, we could successfully isolate a small subpopulation of Nanog-positive cells. We demonstrate that Nanog-positive cells exhibited enhanced ability of self-renewal, clonogenicity, and initiation of tumors, which are consistent with crucial hallmarks in the definition of cancer stem cells (CSCs). NanogPos CSCs could differentiate into mature cancer cells in

in vitro

and

in vivo

conditions. In addition, we found that NanogPos CSCs exhibited resistance to therapeutic agents (e.g., sorafenib and cisplatin) and have a high capacity for tumor invasion and metastasis. Knock-down expression of Nanog in NanogPos CSCs could decrease self-renewal accompanied with decreased expression of stem-cell–related genes and increased expression of mature hepatocyte-related genes. Overexpression of Nanog in NanogNeg cells could restore self-renewal. Furthermore, we found that insulin-like growth factor (IGF)2 and IGF receptor (IGF1R) were up-regulated in NanogPos CSCs. Knock-down expression of Nanog in NanogPos CSCs inhibited the expression of IGF1R, and overexpression of Nanog in NanogNeg cells increased the expression of IGF1R. A specific inhibitor of IGF1R signaling could significantly inhibit self-renewal and Nanog expression, indicating that IGF1R signaling participated in Nanog-mediated self-renewal.

Conclusion
: These data indicate that Nanog could be a novel biomarker for CSCs in HCC, and that Nanog could play a crucial role in maintaining the self-renewal of CSCs through the IGF1R-signaling pathway.
Liver tumorigenicity promoted by microRNA-221 in a mouse transgenic model
Authors: Callegari Elisa , Elamin Bahaeldin K. , Giannone Ferdinando , Milazzo Maddalena , Altavilla Giuseppe , Fornari Francesca , Giacomelli Luciano , D'Abundo Lucilla , Ferracin Manuela , Bassi Cristian , Zagatti Barbara , Corrà Fabio , Miotto Elena , Lupini Laura , Bolondi Luigi , Gramantieri Laura , Croce Carlo M. , Sabbioni Silvia , Negrini Massimo
Published: April 2012

MicroRNA-221 (miR-221) is one of the most frequently and consistently up-regulated microRNAs (miRNAs) in human cancer. It has been hypothesized that miR-221 may act as a tumor promoter. To demonstrate this, we developed a transgenic (TG) mouse model that exhibits an inappropriate overexpression of miR-221 in the liver. Immunoblotting and immunostaining confirmed a concomitant down-regulation of miR-221 target proteins. This TG model is characterized by the emergence of spontaneous nodular liver lesions in approximately 50% of male mice and by a strong acceleration of tumor development in 100% of mice treated with diethylnitrosamine. Similarly to human hepatocellular carcinoma, tumors are characterized by a further increase in miR-221 expression and a concomitant inhibition of its target protein-coding genes (i.e., cyclin-dependent kinase inhibitor [Cdkn]1b/p27, Cdkn1c/p57, and B-cell lymphoma 2–modifying factor). To validate the tumor-promoting effect of miR-221, we showed that

in vivo

delivery of anti-miR-221 oligonucleotides leads to a significant reduction of the number and size of tumor nodules.

Conclusions
: This study not only establishes that miR-221 can promote liver tumorigenicity, but it also establishes a valuable animal model to perform preclinical investigations for the use of anti-miRNA approaches aimed at liver cancer therapy.
Comparison of two modeling approaches for groundwater–surface water interactions
Authors: Guay C. , Nastev M. , Paniconi C. , Sulis M.
Published: April 2012

An assessment of interactions between groundwater and surface water was carried out by applying two different modeling approaches to a small‐scale study area in the municipality of Havelock, Quebec. The first approach involved a commonly used sequential procedure that consists in determining the daily recharge rate using a quasi 2D infiltration model (HELP), applied in the next step as an imposed flux to a 3D finite‐element groundwater flow model. The flow model was calibrated under steady‐state and transient conditions against measured water levels. The second approach was based on a recently developed physically based, 3D fully coupled groundwater–surface water flow model (CATHY) applied to the entire flow domain in an integrated manner. Implementation, calibration, and results of the simulations for both approaches are presented and discussed. For equal annual precipitation (1038 mm/y) and evapotranspiration (556 mm/y), the second approach computed a recharge rate of 233 mm/y (8.9% higher than the first approach) and a net upward flow from the fractured aquifer (the first approach predicted a net downward flow to the rock). The simulated annual discharge was similar for the two approaches (9.6% difference). Both approaches were found to be useful in understanding the interactions between groundwater and surface water, although limitations are apparent in the sequential procedure's inability to account for surface–subsurface feedbacks, for instance near stream reaches where groundwater discharge is prevalent. The decoupled, two‐model approach provides disaggregated surface, vadose, and aquifer flows, and a simple aperçu at the different components of total discharge. The fully coupled model accounts for continuous water exchanges between the land surface, subsurface, and stream channel in a more complex manner, and produces a better match against observed data. Copyright © 2012 John Wiley & Sons, Ltd.
Increased interaction between PACT molecules in response to stress signals is required for PKR activation
Authors: Singh Madhurima , Patel Rekha C.
Published: April 2012

PKR (protein kinase, RNA activated) is an interferon (IFN)‐induced serine‐threonine protein kinase and is one of the key mediators in IFN's cellular actions. Although double‐stranded (ds) RNA is the most relevant PKR activator during viral infections, PACT acts as a stress‐modulated activator of PKR and is an important regulator of PKR dependent signaling pathways in the absence of viral infections. Stress‐induced phosphorylation of PACT is essential for PACT's association with PKR leading to PKR activation. PKR activation by PACT leads to phosphorylation of translation initiation factor eIF2α, inhibition of protein synthesis, and apoptosis. In the present study, we have investigated the functional significance of PACT–PACT interaction in mediating PKR activation in response to cellular stress. Our results suggest that enhanced interaction between PACT molecules when PACT is phosphorylated in response to stress signals on serines 246 and 287 is essential for efficient PKR activation. Using a point mutant of PACT that is deficient in PACT–PACT interaction, we demonstrate that PACT–PACT interaction is essential for efficient PKR activation. J. Cell. Biochem. 113: 2754–2764, 2012. © 2012 Wiley Periodicals, Inc.
Control of Catalytic Activity Via Porosity, Chemical Composition, and Morphology of Nanostructured Porous Manganese Oxide Materials
Authors: Chen Chun‐Hu , Suib Steven, L.
Published: April 2012

This review concerns a summary of synthesis, characterization, and applications of octahedral molecular sieve (OMS) materials. These OMS systems have been the focus of our research program for over 20 years. This review primarily covers the past 10 years with an emphasis on the most recent developments in this area. Some current areas of concern include the systematic synthesis of well ordered materials, control of particle sizes, generation of nano‐size particles, and development of new synthetic methods like pulse laser deposition and epitaxial growth of oxidic materials. Applications include use of OMS in environmental catalysis, adsorption, clean energy materials, activation of the Greenhouse gas carbon dioxide, and selective oxidations. OMS catalysts are outstanding selective oxidation catalysts and can also drive total oxidations. The highly selective of OMS systems may be related to redox cycling and redox catalysis.
Bacterial adherence to separated modular components in joint prosthesis: A clinical study
Authors: Gómez‐Barrena Enrique , Esteban Jaime , Medel Francisco , Molina‐Manso Diana , Ortiz‐Pérez Alberto , Cordero‐Ampuero Jose , Puértolas José A.
Published: April 2012

Bacterial adherence on total joint replacement implants may lead to biofilm formation and implant‐related osteoarticular infection. It is unclear if different biomaterials in the prosthetic components are more prone to facilitate this bacterial adherence, although ultrahigh molecular weight polyethylene (UHMWPE) component exchange in modular systems has been clinically utilized in the early management of these infections. To clarify if the amount of clinically adhered microorganisms was related to the material or the component, we investigated retrieved implants from infected joint replacements. Thirty‐two patients were revised after confirmed implant‐related infection through positive cultures. Eighty‐seven total joint components (hip and knee) were obtained and separately sonicated following a previously published protocol. Cultures were quantified, and detected colony forming units (CFU) were adjusted according to the component surface and compared based on the component material and location. Variable adherence of bacteria to chrome cobalt alloys, UHMWPE, hydroxyapatite coated components, and titanium alloys. The commonest isolated organisms wereStaphylococcus epidermidis(23 of 87 components) andStaphylococcus aureus(10 of 87). Twelve components did not show any microorganism adhered despite location in an infected joint, with positive cultures in other components. A mixed linear model adjusted for random effects (the random effect being the infected patient) obtained convergence for the CFU/mm2variable, but could not confirm a significantly higher adherence to a particular component or to a particular biomaterial. Therefore, the bacterial adherence primarily depends on the infective microorganism and the response of each individual patient, rather than materials or components. © 2012 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 30:1634–1639, 2012
The effect of betaine on in vitro fermentation of carbohydrate and protein combinations under osmotic stress in pigs
Authors: Rink Franziska , Bauer Eva , Eklund Meike , Mosenthin Rainer
Published: April 2012

BACKGROUND: There is evidence that dietary betaine might improve nutrient digestibilities in pigs due to its osmoprotective properties. This in vitro study was performed to assess the potential of supplemented betaine sources to affect fermentation characteristics of different carbohydrate and protein combinations, under conditions of osmotic stress. In vitro fermentation was performed by use of the modified Hohenheim gas test with pig faeces as microbial inoculum.

RESULTS: At the end of in vitro fermentation under osmotic stress conditions, differences (P < 0.05) in gas production, ammonia concentration, and concentration of short‐chain fatty acids were observed for the different carbohydrates, while for the two proteins only differences (P < 0.05) in ammonia and short‐chain fatty acid concentration were obtained. Supplementation of a native betaine source rather than addition of pure betaine increased propionic acid (P < 0.05) and butyric acid (P < 0.05) production.

CONCLUSION: These results suggest that only supplementation of a native betaine source but not of pure betaine products affects microbial fermentation under osmotic stress. Furthermore, both the carbohydrate and protein source play an important role in modifying microbial activity under osmotic stress conditions. It can also be concluded that the modified Hohenheim gas test is suitable to scrutinise fermentation activity of different assay substrates under osmotic stress. Copyright © 2012 Society of Chemical Industry
Wellness Tourism in China: Resources, Development and Marketing
Authors: Heung Vincent C. S. , Kucukusta Deniz
Published: April 2012

China's natural and cultural resources are the foremost offerings of the country's wellness tourism sector. Although wellness tourism in China is in its infancy, it can offer new opportunities in, and strengthen the overall competitiveness of, China's tourism industry. To achieve this, the assessment and development of wellness tourism resources in China are required. This study examines the potential for wellness tourism development in terms of resources and promotion from the point of view of wellness tourism experts. It surveys professionals working in tourism, health and education in China. The results reveal that environmental assets, including fresh air, clean water and natural features, are considered the most important attributes for the development of wellness tourism in China and that the promotion of wellness tourism can best be achieved through advertising in mass media, governmental support and organizing new regional events. The study implications and future research directions are discussed. Copyright © 2012 John Wiley & Sons, Ltd.
Transcendent Experience, Flow and Happiness for Mountain Climbers
Authors: Tsaur Sheng‐Hshiung , Yen Chang‐Hua , Hsiao Shu‐Ling
Published: April 2012

Mountaineering has become a popular form of adventure tourism. However, previous research has never explored the construct of transcendent experience and its effects on mountaineering. The purpose of this study is to investigate the relationships among transcendent experience, flow and happiness. Survey data from 339 mountain climbers in Taiwan indicate that transcendent experience positively affects flow and happiness. In addition, flow mediates the effect of transcendent experience on happiness. However, the relationship between flow and hedonic enjoyment is insignificant for novices. Implications of these findings as well as future research are subsequently discussed. Copyright © 2012 John Wiley & Sons, Ltd.
Incorporating MM Quadruple Bonds Into Conjugated Organic Oligomers: Syntheses and Optoelectronic Properties
Authors: Chisholm Malcolm H.
Published: April 2012

Metal–metal (MM) quadruply bonded units supported by four carboxylate ligands MM(O2CR)4, where MM = Mo2, MoW, or W2 react with dicarboxylic acids or monocarboxylic acids to generate compounds of the form [(RCO2)3MM]2 (O2C–X–CO2) (I), and trans‐MM(O2CR)2 (O2C–X)2 (II), where X is a π‐conjugated group, under appropriate conditions. (I) and (II) provide model compounds for extended‐chain polymers/oligomers of formula [(RCO2)2MM(O2C–X–CO2)] (III). Oxidation of (I) and reduction of (II) lead to mixed valence (MV) metal‐ and organic‐centered ions, respectively, which have been characterized by electron paramagnetic resonance and UV–Vis–near infrared spectroscopy. Photochemical excitation of compounds (I) and (II) leads to metal–ligand charge transfer states. Time‐resolved infrared spectroscopy has been employed to determine the charge distribution and dynamics in the S1 and T1 states.
Expression of a small (p)ppGpp synthetase, YwaC, in the (p)ppGpp0 mutant of Bacillus subtilis triggers YvyD‐dependent dimerization of ribosome
Authors: Tagami Kazumi , Nanamiya Hideaki , Kazo Yuka , Maehashi Marie , Suzuki Shota , Namba Eri , Hoshiya Masahiro , Hanai Ryo , Tozawa Yuzuru , Morimoto Takuya , Ogasawara Naotake , Kageyama Yasushi , Ara Katsutoshi , Ozaki Katsuya , Yoshida Masaki , Kuroiwa Haruko , Kuroiwa Tsuneyoshi , Ohashi Yoshiaki , Kawamura Fujio
Published: April 2012

To elucidate the biological functions of small (p)ppGpp synthetases YjbM and YwaC of Bacillus subtilis, we constructed RIK1059 and RIK1066 strains carrying isopropyl‐β‐D‐thiogalactopyranoside (IPTG) inducible yjbM and ywaC genes, respectively, in the ΔrelA ΔyjbM ΔywaC triple mutant background. While the uninduced and IPTG‐induced RIK1059 cells grew similarly in LB medium, the growth of RIK1066 cells was arrested following the addition of IPTG during the early exponential growth phase. Induction of YwaC expression by IPTG also severely decreased the intracellular GTP level and drastically altered the transcriptional profile in RIK1066 cells. Sucrose density gradient centrifugation analysis of the ribosomal fractions prepared from the IPTG‐induced RIK1066 cells revealed three peaks corresponding to 30S, 50S, and 70S ribosome particles, and also an extra peak. Electron microscope studies revealed that the extra peak fraction contained dimers of 70S ribosomes, which were similar to the Escherichia coli 100S ribosomes. Proteomic analysis revealed that the 70S dimer contained an extra protein, YvyD, in addition to those found in the 70S ribosome. Accordingly, strain resulting from the disruption of the yvyD gene in the RIK1066 cells was unable to form 70S dimers following IPTG induction, indicating that YvyD is required for the formation of these dimers in B. subtilis.
GDNF overexpression fails to provoke muscle recovery from botulinum toxin poisoning: A preliminary study
Authors: Lin Kenny F. , Sun Hank H. , Macewan Matthew R. , Mackinnon Susan E. , Johnson Philip J.
Published: April 2012

Glial cell line‐derived neurotrophic factor (GDNF) has potent axonal growth and survival effects on motoneurons. This study used transgenic Myo‐GDNF mice to assess the effects of targeted GDNF overexpression on functional recovery after botulinum toxin type A (BTxA) chemodenervation. BTxA (0.1 U) was injected into the tibialis anterior (TA) muscle of wild‐type CF1 and transgenic Myo‐GDNF mice. On days 1, 7, 14, and 21 after injection, evoked muscle force production and muscle mass were measured (n = 6, for each group at each time point). Greater maximal tetanic force and calculated specific force were evoked in Myo‐GDNF animals when compared with control CF1 animals at days 1, 7, and 21. However, the differences were not statistically significant. Similarly, modest reductions in muscle atrophy in the Myo‐GDNF group at all time points were not statistically significant. Targeted overexpression of GDNF in the muscles of Myo‐GDNF mice did not improve motor recovery in the first 21 days after BTxA chemodenervation. © 2012 Wiley Periodicals, Inc. Microsurgery, 2012.
Free transverse rectus abdominis myocutaneous flap reconstruction of a massive lumbosacral defect using superior gluteal artery perforator vessels
Authors: Gaster Richard S. , Bhatt Kirit A. , Shelton Andrew A. , Lee Gordon K.
Published: April 2012

Despite significant advances in reconstructive surgery, the repair of massive lumbosacral defects poses significant challenges. When the extent of soft tissue loss, tumor resection, and/or radiation therapy preclude the use of traditional local options, such as gluteal advancement flaps or pedicled thigh flaps, then distant flaps are required. We report a case of a 64‐year‐old male who presented with a large sacral Marjolin's ulcer secondary to recurrent pilonidal cysts and ulcerations. The patient underwent wide local composite resection, which resulted in a wound measuring 450 cm2 with exposed rectum and sacrum. The massive defect was successfully covered with a free transverse rectus abdominis myocutaneous flap, providing a well‐vascularized skin paddle and obviating the need for a latissimus flap with skin graft. The free‐TRAM flap proved to be a very robust flap in this situation and would be one of our flaps of choice for similar defects. © 2012 Wiley Periodicals, Inc. Microsurgery, 2012.
Stability of anchored sheet wall in cohesive‐frictional soils by FE limit analysis
Authors: Muñoz J. J. , Lyamin A. V. , Huerta A.
Published: April 2012

This study extends the limit analysis techniques used for the computation of strict bounds of the load factors in solids to stability problems with interfaces, anchors and joints. The cases considered include the pull‐out capacity of multi‐belled anchors and the stability of retaining walls for multiple conditions at the anchor/soil and wall/soil interfaces. Three types of wall supports are examined: free standing wall, simply supported wall and anchored wall. The results obtained are compared against available experimental and numerical data. The conclusion drawn confirms the validity of numerical limit analysis for the computation of accurate bounds on limit loads and capturing failure modes of structures with multiple inclusions of complex interfaces and support conditions. Copyright © 2012 John Wiley & Sons, Ltd.
Dynamic simulation of damage‐fracture transition in smoothed particles hydrodynamics shells
Authors: Caleyron F. , Combescure A. , Faucher V. , Potapov S.
Published: April 2012

This paper presents a meshless method for the modeling of shell‐type structures in fast dynamics. The model is based on the Mindlin–Reissner theory and takes into account material and geometric nonlinearities. The phenomena that occur prior to rupture are dealt with using damage laws, while the rupture itself is represented through the introduction of sharp discontinuities. The method does not represent cracks explicitly, which makes the treatment of multicracking easier. The time discretization is carried out in the framework of explicit dynamics, and the spatial discretization is handled through the smoothed particles hydrodynamics method and the use of moving least square functions. The capabilities of the method are demonstrated using cracking, puncturing and fragmentation examples. Copyright © 2012 John Wiley & Sons, Ltd.
Bipenalty method from a frequency domain perspective
Authors: Ilanko Sinniah , Monterrubio Luis E.
Published: April 2012

In a recent paper, it was shown that for time domain analysis, the simultaneous use of inertial and stiffness type penalty parameters to enforce constraints was found to yield accurate and converging results without causing any stability problems. From a frequency domain perspective, this is somewhat unexpected because the solution converges from below when stiffness penalty parameters are used to model constraints, and the convergence is from above when inertial penalty parameters are used. The purpose of this paper is to explain the effect of the simultaneous use of stiffness and inertial penalty parameters on the natural frequencies of constrained systems. In this work, it is shown that if suitably tuned, the bipenalty approach works well for frequency domain analysis also, and that with two different tuned set of stiffness and inertial penalty parameters, bounded solutions to the natural frequencies of constrained systems may be obtained. The method is applicable for any linear eigenvalue problem. Copyright © 2012 John Wiley & Sons, Ltd.
Graduate medical education changes: Yes we can or enough already?
Authors: Leavey Patrick J. , Jubran Rima F.
Published: April 2012

The Accreditation Council for Graduate Medical Education (ACGME) established new duty hour recommendations for pediatric subspecialty trainees in July 2011. Short‐term and long‐term implications to Pediatric Hematology/Oncology (PHO) are reviewed. Other modifications have been introduced by the ACGME and the American Board of Pediatrics (ABP) in the last decade, including the introduction of the six core competencies and an expansion in the definition of scholarship for fellows. The effect of these on fellows are discussed with suggested strategies for PHO to prepare for further change likely to result from a new ABP initiative to evaluate subspecialty training and certification over the next 3 years. Pediatr Blood Cancer 2012; 59: 1168–1172. © 2012 Wiley Periodicals, Inc.
Multiplex ligation‐dependent probe amplification (MLPA) and prenatal diagnosis
Authors: Willis Alecia S. , van den Veyver Ignatia , Eng Christine M.
Published: April 2012

Multiplex ligation‐dependent probe amplification (MLPA) is a recent technique for the relative quantitation of up to 40 to 45 nucleic acid targets. Due to its relative simplicity, low cost, and availability of laboratory‐developed and more than 300 commercially‐developed assays, MLPA has become more widely used for both research and diagnostic applications. The MLPA platform is now extensively applied for postnatal diagnosis of genetic disorders and has recently been used for prenatal diagnosis. The published uses of MLPA for prenatal diagnosis include detection of aneuploidies, common microdeletion syndromes and subtelomeric copy‐number changes, identification of marker chromosomes, and detection of familial copy‐number changes in single genes. This review describes the technique of MLPA in detail and offers considerations for the interpretation of results in the clinical diagnostic setting. © 2012 John Wiley & Sons, Ltd.
Molecular recognition: polymers comprising isomeric meta‐/para‐isopropylphenol and N‐isopropylacrylamide and their supramolecular complexes with methylated β‐cyclodextrin
Authors: Gingter Sabrina , van Sloun Claudia , Ritter Helmut
Published: April 2012

We describe the molecular recognition of polymeric attached isomers meta‐isopropylphenol and para‐isopropylphenol, respectively, in a copolymer of N‐isopropylacrylamide (NIPAAm) by use of randomly methylated β‐cyclodextrin (RAMEB‐CD). The acrylic monomers 4‐ and 3‐isopropylphenylacrylate were synthesized and radically copolymerized with NIPAAm yielding the corresponding polymers. The supramolecular structures resulting from complexation with RAMEB‐CD were characterized using dynamic light scattering, turbidity, NMR spectroscopy and isothermal titration. We found differences in binding constant, mean coil size and cloud point as a result of different complexations of the mentioned polymer‐bound isomers with RAMEB‐CD. Copyright © 2012 Society of Chemical Industry
Incorporation of steroidal biomarkers into petroleum model compounds
Authors: Scherer Alexander , Hampel Frank , Gray Murray R. , Stryker Jeffrey M. , Tykwinski Rik R.
Published: April 2012

A series of fully‐substituted 5,6‐benzoquinolines covalently fused to the chlolestane framework has been synthesized to serve as model compounds for the poorly characterized components found in the heaviest fractions of petroleum, namely the asphaltenes. Acid‐catalyzed cyclocondensation of an aromatic imine with 5‐α‐cholestan‐3‐one gives 5,6‐benzoquinoline cycloadducts incorporating the steroidal biomarker fused to the benzoquinoline system at the 3,4‐positions, with various pendent substituents in the 2‐position. X‐ray crystallography of three such derivatives shows that the solid‐state geometries of these molecules are quite similar, and packing in the solid state appears to be dominated to a great extent by the nature of the pendent substituent. X‐ray crystallography and solution phase circular dichroism spectroscopy together suggest that the conjugated benzoquinoline moiety adopts a helical conformation. Copyright © 2012 John Wiley & Sons, Ltd.
Synthesis and characteristics of poly(N‐isopropylacrylamide‐co‐methacrylic acid)/Fe3O4 thermosensitive magnetic composite hollow latex particles
Authors: Lee Chia‐Fen , Lin Mei‐Ling , Wang Yu‐Cheng , Chiu Wen‐Yen
Published: April 2012

In this study, the poly(NIPAAm–MAA)/Fe3O4 hollow latex particles were synthesized by three steps. The first step was to synthesize the poly(methyl methacrylate‐co‐methylacrylate acid) (poly(MMA‐MAA)) copolymer latex particles by the method of soapless emulsion polymerization. Following the first step, the second step was to polymerize N‐isopropylacrylamide (NIPAAm), MAA, and crosslinking agent (N,N'‐methylene‐bisacrylamide (MBA)) in the presence of poly(MMA‐MAA) latex particles to form the linear poly(MMA‐MAA)/crosslinking poly (NIPAAm‐MAA) core‐shell latex particles. After the previous processes, the core‐shell latex particles were heated in the presence of NH4OH to dissolve the linear poly(MMA‐MAA) core in order to form the poly(NIPAAm‐MAA) hollow latex particles. In the third step, Fe2+ and Fe3+ ions were introduced to bond with the COOH groups of MAA segments in the poly(NIPAAm‐MAA) hollow polymer latex particles. Further by a reaction with NH4OH and then Fe3O4 nanoparticles were generated in situ and the poly(NIPAAm‐MAA)/Fe3O4 magnetic composite hollow latex particles were formed. The concentrations of MAA, crosslinking agent (N,N'‐methylene bisacrylamide), and Fe3O4 nanoparticles were important factors to influence the morphology of hollow latex particles and lower critical solution temperature of poly(NIPAAm–MAA)/Fe3O4 magnetic composite hollow latex particles. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
PDMS network blends of amphiphilic acrylic copolymers with poly(ethylene glycol)‐fluoroalkyl side chains for fouling‐release coatings. I. Chemistry and stability of the film surface
Authors: Martinelli Elisa , Sarvothaman Mahesh K. , Alderighi Michele , Galli Giancarlo , Mielczarski Ela , Mielczarski Jerzy A.
Published: April 2012

Amphiphilic copolymers of a methacrylic monomer (SiMA) carrying a polysiloxane side chain and an acrylic monomer (ZA) with a mixed poly(ethylene glycol) (PEG)‐fluoroalkyl side chain (10–85 mol % ZA) were incorporated as the surface‐active components into poly(dimethylsiloxane) (PDMS) network blends at different loadings (1 and 4 wt % with respect to PDMS). Wettability of the coating surfaces was investigated by contact angle measurements, and their surface chemical composition was determined by angle‐resolved X‐ray photoelectron spectroscopy. It was found that the surface segregation of the fluoroalkyl segments of the amphiphilic copolymers was responsible for the high enrichment in fluorine concentration within 10 nm of the coating surface. The PEG segments were also concentrated at the polymer−air interface. The chemical composition of the films was proven to be relatively little affected by immersion in water. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Amphiphilic Block‐Graft Copolymers Poly(ethylene glycol)‐b‐(polycarbonates‐g‐palmitate) Prepared via the Combination of Ring‐Opening Polymerization and Click Chemistry
Authors: Zhang Xiaojin , Zhang Zhenguo , Zhong Zhenlin , Zhuo Renxi
Published: April 2012

Amphiphilic block‐graft copolymers mPEG‐b‐P(DTC‐ADTC‐g‐Pal) were synthesized by ring‐opening polymerization of 2,2‐dimethyltrimethylene carbonate (DTC) and 2,2‐bis(azidomethyl)trimethylene carbonate (ADTC) with poly(ethylene glycol) monomethyl ether (mPEG) as an initiator, followed by the click reaction of propargyl palmitate and the pendant azido groups on the polymer chains. Stable micelle solutions of the amphiphilic block‐graft copolymers could be prepared by adding water to a THF solution of the polymer followed by the removal of the organic solvent by dialysis. Dynamic light scattering measurements showed that the micelles had a narrow size distribution. Transmission electron microscopy images displayed that the micelles were in spherical shape. The grafted structure could enhance the interaction of polymer chains with drug molecules and improve the drug‐loading capacity and entrapment efficiency. Further, the amphiphilic block‐graft copolymers mPEG‐b‐P(DTC‐ADTC‐g‐Pal) were low cytotoxic and had more sustained drug release behavior. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Variability of a closed, rebreathing setup for multiple breath wash‐out testing in children
Authors: Pittman Jessica E. , Johnson Robin C. , Jones Paul W. , Davis Stephanie D.
Published: April 2012

Objective

The multiple breath wash‐out technique (MBW) that measures lung clearance index (LCI) and functional residual capacity (FRC) may be more sensitive than spirometry for identification of early obstructive airways disease. The open MBW setup using mass spectrometry referenced in previous publications is not readily available in the U.S. Our objective was to assess validity and sensitivity of a commercially available device that uses a closed (rebreathing) setup with photoacoustic spectroscopy for MBW testing.

Study Design and Methods

Subjects aged 5–21 who were either healthy or had a history of cystic fibrosis were enrolled. Subjects completed MBW (Innocor device; Innovision, Denmark) and spirometry; measures obtained included LCI, FRC, and forced expiratory volume in 1 sec, as well as changes in end‐tidal carbon dioxide levels (CO2) and tidal volume during MBW testing.

Results

Seventeen subjects attempted a total of 76 MBW maneuvers; 80% were completed and 60% met criteria for acceptability; most were unacceptable due to errors in the tracer gas curve. Substantial intra‐subject variability for LCI and FRC were noted (mean 26% ± 55 and 36% ± 63, respectively). Subjects were also noted to have significant increases in exhaled CO2 and tidal volume during MBW testing.

Conclusions

In our initial experience using a commercially available closed setup for MBW testing, we found a significant degree of intra‐subject variability leading us to suspend testing. Variability could be due to hypercapnea and instability of tidal breathing secondary to the rebreathing setup. Further studies are needed to better understand the closed system MBW setup. Pediatr Pulmonol. 2012; 47:1242–1250. © 2012 Wiley Periodicals, Inc.
Spectral characteristics and dynamics of a light hole type quantum dot doped with a single Mn atom
Authors: Reiter D. E. , Axt V. M. , Kuhn T.
Published: April 2012

For a single semiconductor quantum dot doped with a single Mn atom we study theoretically the spectral characteristics and dynamics under optical excitation. Because the Mn spin couples to the electron and hole spin of the quantum dot exciton via the exchange interaction, in the absorption spectrum instead of a single exciton line a set of lines appears. Here we consider a quantum dot with one conduction band and one light hole type valence band. Due to this untypical valence band structure a spectrum of twelve lines is seen at zero magnetic field. When a magnetic field is applied, the lines shift, cross and anticross. By an analysis of the corresponding eigenvalues and eigenfunctions as functions of the magnetic field more insight into the spectral behavior can be achieved. The exchange interaction furthermore opens the possibility for ultra fast control of the Mn spin via optical manipulation of the exciton. We analyze whether switching of the Mn spin can be optimized by the application of an external magnetic field. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Terahertz transitions in Aharonov‐Bohm quantum rings in an external electric field
Authors: Alexeev A. M. , Portnoi M. E.
Published: April 2012

Magneto‐oscillations of the electric dipole moment are predicted and analyzed for a single‐electron nanoscale ring pierced by a magnetic flux (an Aharonov‐Bohm ring) and subjected to an electric field in the ring's plane.

These oscillations are accompanied by periodic changes in the selection rules for inter‐level optical transitions in the ring allowing control of polarization properties of the associated terahertz radiation. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structuration and Integration of Magnetic Nanoparticles on Surfaces and Devices
Authors: Bellido Elena , Domingo Neus , Ojea‐Jiménez Isaac , Ruiz‐Molina Daniel
Published: April 2012

Different experimental approaches used for structuration of magnetic nanoparticles on surfaces are reviewed. Nanoparticles tend to organize on surfaces through self‐assembly mechanisms controlled by non‐covalent interactions which are modulated by their shape, size and morphology as well as by other external parameters such as the nature of the solvent or the capping layer. Further control on the structuration can be achieved by the use of external magnetic fields or other structuring techniques, mainly lithographic or atomic force microscopy (AFM)‐based techniques. Moreover, results can be improved by chemical functionalization or the use of biological templates. Chemical functionalization of the nanoparticles and/or the surface ensures a proper stability as well as control of the formation of a (sub)monolayer. On the other hand, the use of biological templates facilitates the structuration of several families of nanoparticles, which otherwise may be difficult to form, simply by establishing the experimental conditions required for the structuration of the organic capsule. All these experimental efforts are directed ultimately to the integration of magnetic nanoparticles in sensors which constitute the future generation of hybrid magnetic devices.
Leistungsfähige Spiegel für solarthermische Kraftwerke
Authors: Schiller Matthias , Höing Thomas
Published: April 2012

Spiegel sind ein wesentlicher Bestandteil solarthermischer Kraftwerke. Mittels Nasschemie hergestellte Silberspiegel der Flabeg GmbH erreichen in Kombination mit speziellem Solarglas eine solare, gerichtete Reflexion von im Mittel 94,4%. Fast 30 Jahre Felderfahrung sind ein Beweis für die Beständigkeit der Beschichtung.

Mit Oberflächenspiegeln könnte man die Reflexion weiter erhöhen, doch lassen sie sich noch nicht in der gewünschten Qualität bzw. zu einem wettbewerbsfähigen Preis herstellen.

Ein anderer Ansatz zur Erhöhung der Reflexion ist die Ausstattung mit einer schmutzabweisenden Beschichtung. Solche Spiegel befinden sich in Feldtests, die bereits vielversprechende Ergebnisse zeigen.

Mit neuartigen Lacksystemen wird es möglich sein, Silberspiegel auch in küstennahen Regionen oder den Tropen einzusetzen.
Electron transfer in DNA
Authors: Siriwong Khatcharin , Voityuk Alexander A.
Published: April 2012

During the last two decades, electron transfer (ET) through DNA and its artificial analogues has been an area of extensive experimental and theoretical studies. This process plays an important role in biology (damage and repair of DNA in living cells) and is of potential interest in material sciences. Because structural dynamics of the π stack and its environment affect essentially the electron transport, some significant details of excess charge migration cannot be derived from experiments. Computer simulations of the ET process provide microscopic insights into mechanisms of this process. In the paper, we consider computational methods used to describe the propagation of excess charges through π stacks of DNA and related systems. © 2012 John Wiley & Sons, Ltd.

This article is categorized under:

Molecular and Statistical Mechanics > Molecular Dynamics and Monte-Carlo Methods
P2Y receptors in microglia and neuroinflammation
Authors: Hidetoshi Tozaki‐Saitoh , Makoto Tsuda , Inoue Kazuhide
Published: April 2012

Microglia are surveillants in the central nervous system. Once they find abnormal or emergency signals, microglia can migrate to the site of the injury, release pro‐inflammatory and/or neurotrophic substances, and phagocytose damaged cells and their remnants. Extracellular nucleotides act through purinoceptors and have been implicated as signaling molecules used by microglia to sense adverse physiological conditions. The P2Y12 receptor is responsible for microglial chemotactic function toward an ATP source. The P2Y6 receptor stimulates phagocytic activity of microglia in response to extracellular UDP. Each receptor elicits transient intracellular calcium elevation and this may induce the expression of several genes related to microglial activation. Both receptor‐mediated signaling and cellular functions may be involved in the pathology occurring in the central nervous system. Therefore, determining the definitive microglial functions mediated by P2Y receptors supports understanding the pathological cascade and finding new therapeutic targets related to microglia. WIREs Membr Transp Signal 2012, 1:493–501. doi: 10.1002/wmts.46

For further resources related to this article, please visit the WIREs website.

Conflict of interest: The authors have no conflict of interest to declare.
Faculty and student perceptions of the feasibility of individual student–faculty
meetings
Authors: Mulder B. F. , Erich M. H. , Borleffs J. C. C. , Elgersma A. F. , Cohen-Schotanus J.
Published: April 2012

The extent to which students feel involved in their education positively
influences academic achievement. Individual student–faculty meetings can foster student
involvement. To be effective, faculty acknowledgement of the benefit of these meetings
is a prerequisite. The aim of this study was to explore faculty perceptions of
individual student–faculty meetings. In addition we investigated students’ perceptions.
As part of the undergraduate programme, mandatory individual intake and follow-up
meetings between first-year medical students (n = 425) and senior faculty members
(n = 34) have been implemented from 2009 onwards. We administered a questionnaire on
faculty perceptions of the benefit and impact of intake meetings. Subsequently, after
both meetings had been held, strong and weak points of the mandatory programme were
explored using open-ended questions. Students’ perceptions were investigated by
open-ended questions as a part of the curriculum evaluation process. Faculty enjoyed the
meetings (90 %), perceived the meetings to be beneficial (74 %) and expected a positive
effect on student involvement (74 %). Faculty appreciated the opportunity to give advice
tailored to students’ personal needs and levels of performance. The students appreciated
the meetings and the attention given to their personal situation and study progress.
Faculty and student appreciation of the meetings seems to support the assumption that
the individual meetings increase students’ social and academic involvement. Further
research should focus on the impact of individual student–faculty meetings on students’
learning behaviours.