bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence for a virtual human analog of a rodent relational memory task: A study of aging and fMRI in young adults
Authors: Etchamendy Nicole , Konishi Kyoko , Pike G. Bruce , Marighetto Aline , Bohbot Véronique D. 
Published: June 2011

AbstractA radial maze concurrent spatial discrimination learning paradigm consisting of two stages was previously designed to assess the flexibility property of relational memory in mice, as a model of human declarative memory. Aged mice and young adult mice with damage to the hippocampus, learned accurately Stage 1 of the task which required them to learn a constant reward location in a specific set of arms (i.e., learning phase). In contrast, they were impaired relative to healthy young adult mice in a second stage when faced with rearrangements of the same arms (i.e., flexibility probes). This mnemonic inflexibility in Stage 2 is thought to derive from insufficient relational processing by the hippocampus during initial learning (Stage 1) which favors stimulus‐response learning, a form of procedural learning. This was proposed as a model of the selective declarative and relational memory decline classically described in elderly people. As a first step to examine the validity of this model, we adapted this protocol to humans using a virtual radial‐maze. (1) We showed that performance in the flexibility probes in young and older adults positively correlated with performance in a wayfinding task, suggesting that our paradigm assesses relational memory. (2) We demonstrated that older healthy participants displayed a deficit in the performance of the flexibility probes (Stage 2), similar to the one previously seen in aged mice. This was associated with a decline in the wayfinding task. (3) Our fMRI data in young adults confirmed that hippocampal activation during early discrimination learning in Stage 1 correlated with memory flexibility in Stage 2, whereas caudate nucleus activation in Stage 1 negatively correlated with subsequent flexibility. By enabling relational memory assessment in mice and humans, our radial‐maze paradigm provides a valuable tool for translational research. © 2011 Wiley Periodicals, Inc.
Decoding representations of scenes in the medial temporal lobes
Authors: Bonnici Heidi M. , Kumaran Dharshan , Chadwick Martin J. , Weiskopf Nikolaus , Hassabis Demis , Maguire Eleanor A. 
Published: June 2011

AbstractRecent theoretical perspectives have suggested that the function of the human hippocampus, like its rodent counterpart, may be best characterized in terms of its information processing capacities. In this study, we use a combination of high‐resolution functional magnetic resonance imaging, multivariate pattern analysis, and a simple decision making task, to test specific hypotheses concerning the role of the medial temporal lobe (MTL) in scene processing. We observed that while information that enabled two highly similar scenes to be distinguished was widely distributed throughout the MTL, more distinct scene representations were present in the hippocampus, consistent with its role in performing pattern separation. As well as viewing the two similar scenes, during scanning participants also viewed morphed scenes that spanned a continuum between the original two scenes. We found that patterns of hippocampal activity during morph trials, even when perceptual inputs were held entirely constant (i.e., in 50% morph trials), showed a robust relationship with participants' choices in the decision task. Our findings provide evidence for a specific computational role for the hippocampus in sustaining detailed representations of complex scenes, and shed new light on how the information processing capacities of the hippocampus may influence the decision making process. © 2011 Wiley Periodicals, Inc.
A chirality‐based metrics for free‐energy calculations in biomolecular systems
Authors: Pietropaolo Adriana , Branduardi Davide , Bonomi Massimiliano , Parrinello Michele 
Published: June 2011

AbstractIn this work, we exploit the chirality index introduced in (Pietropaolo et al., Proteins 2008, 70, 667) as an effective descriptor of the secondary structure of proteins to explore their complex free‐energy landscape. We use the chirality index as an alternative metrics in the path collective variables (PCVs) framework and we show in the prototypical case of the C‐terminal domain of immunoglobulin binding protein GB1 that relevant configurations can be efficiently sampled in combination with well‐tempered metadynamics. While the projections of the configurations found onto a variety of different descriptors are fully consistent with previously reported calculations, this approach provides a unifying perspective of the folding mechanism which was not possible using metadynamics with the previous formulation of PCVs. © 2011 Wiley Periodicals, Inc. J Comput Chem, 2011
Value of contrast‐enhanced sonography with micro flow imaging in the diagnosis of prostate cancer
Authors: Xie Shao Wei , Li Feng Hua , Li Hong Li , Du Jing , Xia Jian Guo , Fang Hua , Bo Juan Jie , Zhu Jian Shan 
Published: June 2011

AbstractBackground.To evaluate the effectiveness of contrast‐enhanced sonographic micro flow imaging (MFI) in the diagnosis of prostate cancer.Methods.A total of 74 patients referred for prostate biopsy were prospectively evaluated with MFI. The abnormalities were categorized into four patterns: pattern 1: indistinct separation between the inner and outer gland; pattern 2: asymmetrical or focally increased enhancement in the outer gland; pattern 3: enhancement with focal defect; pattern 4: enhancement in the outer gland equal to that of the inner gland. The findings were correlated with Gleason scores.Results.Prostate cancer was detected in 264 sites in 41 patients. The sensitivity, specificity, accuracy, and positive and negative predictive values for MFI were 81.1%, 84.3%, 83.3%, 68.6%, and 91.3%, respectively. Positive predictive values for the four patterns were 46.0 (pattern 1), 53.6 (pattern 2), 94.3 (pattern 3), and 95.4 (pattern 4). Gleason scores of cancers with patterns 3 (7.09) or 4 (7.51) were significantly higher than those with patterns 1 (6.17) or 2 (6.59) (p = 0.001, p = 0.005, p < 0.001, p < 0.001).Conclusions.Some MFI patterns had high positive predictive values and were associated with more aggressive cancers. This could be used to reduce the number of biopsy sites and detect clinically significant cancers. © 2011 Wiley Periodicals, Inc. J Clin Ultrasound, 2011
Symptomatic plantar fibroma with a unique sonographic appearance
Authors: Haun Daniel W. , Cho John C.S. , Kettner Norman W. 
Published: June 2011

AbstractWe present a case of a solitary plantar fibroma with unique sonographic features with MRI and pathologic correlation. A 25‐year‐old woman presented with a left foot mass that interfered with her gait. Sonography demonstrated a well‐circumscribed, 32 mm × 27 mm × 14 mm subcutaneous mass with heterogeneous echogenicity. Unique sonographic characteristics included posterior acoustic enhancement, cystic components, and mild intratumoral hypervascularity. MRI confirmed the sonographic findings. Surgical excision was performed without complication. A pathologic diagnosis of fibroma with myxoid degeneration and cyst formation was made. © 2011 Wiley Periodicals, Inc. J Clin Ultrasound 40:114–112, 2012
Synthesis of heterocyclic derivatives of alkyl 2‐(cyanomethyl)‐4‐methyl‐3‐quinolinecarboxylates
Authors: Degtyarenko Alexey S. , Tolmachev Andrey A. , Volovenko Yulian M. 
Published: June 2011

AbstractThe article reports reactions of a series of known alkyl 2‐(cyanomethyl)‐4‐methyl‐3‐quinolinecarboxylates. In the course of the present study the synthesis of new heterocyclic derivatives of alkyl 2‐(cyanomethyl)‐4‐methyl‐3‐quinolinecarboxylates was achieved. J. Heterocyclic Chem., (2011).
Ageing‐induced solubility loss in milk protein concentrate powder: effect of protein conformational modifications and interactions with water
Authors: Haque Enamul , Bhandari Bhesh R , Gidley Michael J , Deeth Hilton C , Whittaker Andrew K 
Published: June 2011

AbstractBACKGROUND: Protein conformational modifications and water‐protein interactions are two major factors believed to induce instability of protein and eventually affect the solubility of milk protein concentrate (MPC) powder. To test these hypotheses, MPC was stored at different water activities (aw 0.0–0.85) and temperatures (25 and 45 °C) for up to 12 weeks. Samples were examined periodically to determine solubility, change in protein conformation by Fourier transform infrared (FTIR) spectroscopy and water status (interaction of water with the protein molecule/surface) by measuring the transverse relaxation time (T2) with proton nuclear magnetic resonance (1H NMR).RESULTS: The solubility of MPC decreased significantly with ageing and this process was enhanced by increasing water activity (aw) and temperature. Minor changes in protein secondary structure were observed with FTIR which indicated some degree of unfolding of protein molecules. The NMR T2 results indicated the presence of three distinct populations of water molecules and the proton signal intensity and T2 values of proton fractions varied with storage condition (humidity) and ageing.CONCLUSION: Results suggest that protein/protein interactions may be initiated by unfolding of protein molecules that eventually affects solubility. Copyright © 2011 Society of Chemical Industry
Comparative biology of cAMP‐induced germinal vesicle breakdown in marine invertebrate oocytes
Authors: Deguchi Ryusaku , Takeda Noriyo , Stricker Stephen A. 
Published: June 2011

AbstractDuring maturation, oocytes must undergo a process of nuclear disassembly, or “germinal vesicle breakdown” (GVBD), that is regulated by signaling pathways involving cyclic AMP (cAMP). In vertebrate and starfish oocytes, cAMP elevation typically prevents GVBD. Alternatively, increased concentrations of intra‐oocytic cAMP trigger, rather than inhibit, GVBD in several groups of marine invertebrates. To integrate what is known about the stimulation of GVBD by intra‐oocytic cAMP, this article reviews published data for ascidian, bivalve, brittle star, jellyfish, and nemertean oocytes. The bulk of the review concentrates on the three most intensively analyzed groups known to display cAMP‐induced GVBD—nemerteans, ascidians, and jellyfish. In addition, this synopsis also presents some previously unpublished findings regarding the stimulatory effects of intra‐oocytic cAMP on GVBD in jellyfish and the annelid worm Pseudopotamilla occelata. Finally, factors that may account for the currently known distribution of cAMP‐induced GVBD across animal groups are discussed. Mol. Reprod. Dev. 78:708–725, 2011. © 2011 Wiley Periodicals, Inc.
Testing a multi‐group model of culturally competent behaviors among underrepresented nurse practitioners
Authors: Benkert Ramona , Templin Thomas , Schim Stephanie Myers , Doorenbos Ardith Z. , Bell Sue Ellen 
Published: June 2011

AbstractDiversifying the health professional workforce and enhancing cultural competence are recommended for decreasing health disparities. We tested a structural equation model of the predictors of culturally competent behaviors in a mailed survey of three groups of underrepresented nurse practitioners (n = 474). Our model had good fit and accounted for 29% of the variance in culturally competent behaviors. Life experiences with diversity had direct effects on awareness/sensitivity and behaviors, and diversity training had a direct effect on behaviors. Cultural awareness/sensitivity mediated the relationship between life experiences with diversity and culturally competent behaviors; all paths remained after controlling for covariates. For unique experiences that contribute to workplace diversity, life experiences with diversity, and diversity training are important for culturally competent behaviors. © 2011 Wiley Periodicals, Inc. Res Nurs Health 34:327–341, 2011
Impact behavior of particles filled‐glass/polyester composite plates
Authors: Çallıoğlu Hasan , Sayer Metin , Demir Ersin 
Published: June 2011

AbstractThe aim of the study is to lay bare the impact behavior of filled composite plates experimentally. The woven glass/polyester‐matrix composite plates filled with 0% (unfilled), 10%, and 20% SiCp ceramic particles were manufactured by hand lay‐up method. The low velocity drop impact testing is conducted to the composite samples subjected to increasing impact energies that were ranged from approximately 2.5 to 22.5 J. With this use of increasing impact energies, it was possible to examine the impact response and damage mechanism until perforation of the composite plates. An energy profiling method was used in order to identify the perforation thresholds of composites. It is concluded that addition of particles to resin, until a certain ratio, increases the perforation thresholds of the woven glass/polyester. The perforation threshold of 10% filled composite is about 37% higher than that of the 20% filled composite and 6% higher than ones of the unfilled composite. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers
“Click” synthesis of thermally stable au nanoparticles with highly grafted polymer shell and control of their behavior in polymer matrix
Authors: Lim Jongmin , Yang Hyunseung , Paek Kwanyeol , Cho Chul‐Hee , Kim Seyong , Bang Joona , Kim Bumjoon J. 
Published: June 2011

AbstractThermally stable core–shell gold nanoparticles (Au NPs) with highly grafted polymer shells were synthesized by combining reversible addition‐fragmentation transfer (RAFT) polymerization and click chemistry of copper‐catalyzed azide‐alkyne cycloaddition (CuAAC). First, alkyne‐terminated poly(4‐benzylchloride‐b‐styrene) (alkyne‐PSCl‐b‐PS) was prepared from the alkyne‐terminated RAFT agent. Then, an alkyne‐PSCl‐b‐PS chain was coupled to azide‐functionalized Au NPs via the CuAAC reaction. Careful characterization using FT‐IR, UV–Vis, and TGA showed that PSCl‐b‐PS chains were successfully grafted onto the Au NP surface with high grafting density. Finally, azide groups were introduced to PSCl‐b‐PS chains on the Au NP surface to produce thermally stable Au NPs with crosslinkable polymer shell (Au‐PSN3‐b‐PS 1). As the control sample, PS‐b‐PSN3‐coated Au NPs (Au‐PSN3‐b‐PS 2) were made by the conventional “grafting to” approach. The grafting density of polymer chains on Au‐PSN3‐b‐PS 1 was found to be much higher than that on Au‐PSN3‐b‐PS 2. To demonstrate the importance of having the highly packed polymer shell on the nanoparticles, Au‐PSN3‐b‐PS 1 particles were added into the PS and PS‐b‐poly(2‐vinylpyridine) matrix, respectively. Consequently, it was found that Au‐PSN3‐b‐PS 1 nanoparticles were well dispersed in the PS matrix and PS‐b‐P2VP matrix without any aggregation even after annealing at 220 °C for 2 days. Our simple and powerful approach could be easily extended to design other core–shell inorganic nanoparticles. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011
Liquid phase demixing in ferroelectric/semiconducting polymer blends: An experimental and theoretical study
Authors: Michels Jasper J. , van Breemen Albert J. J. M. , Usman Khurram , Gelinck Gerwin H. 
Published: June 2011

AbstractThis article describes a combined experimental and theoretical study on nanophase structure development as a result of liquid phase demixing in solution‐cast blends of the organic semiconductor poly(9,9′‐dioctyl fluorene) (PFO) and the ferroelectric polymer poly(vinylidene fluoride‐co‐trifluoroethylene) (P(VDF‐TrFE)). Blend layers (200 nm) are prepared by spin coating a 1:9 (w/w) PFO:P(VDF‐TrFE) blend solution in a common solvent on a poly(ethylenedioxy thiophene)/poly(styrene sulfonate) substrate. Owing to the pronounced incompatibility between the two polymers, a strong phase‐separated morphology is obtained, characterized by disk‐like nanodomains of PFO embedded in a P(VDF‐TrFE) matrix, as revealed by scanning electron microscopy. By varying the processing conditions, we find the average domain size and standard deviation to increase with spinning time. The considerable increase in domain size suggests the coarsening process not to be impeded by a steep rise in viscosity. This indicates solvent evaporation to be only moderate within the experimental time frame. The evolution of the observed phase morphology is modeled using ternary diffuse interface theory integrated with a modified Flory–Huggins (FH) treatment of the homogeneous (bulk) free energy of mixing, to account for significant molecular differences between the active blend components. Using calculated FH interaction parameters, the model confirms the phase separation to occur via spinodal decomposition of the blend solution during spin coating, as suggested by experimental observations. The simulated phase morphologies as well as the modeled trends in domain growth and standard deviation compare favorably with the experimental data. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1255–1262, 2011
Development of internal fine structure in stretched rubber vulcanizates
Authors: Tosaka Masatoshi , Toki Shigeyuki , Che Justin , Rong Lixia , Hsiao Benjamin S. 
Published: June 2011

AbstractSmall‐angle X‐ray scattering (SAXS) pattern and tensile stress during relaxation of stretched rubber vulcanizates (synthetic polyisoprene) were measured simultaneously at room temperature and at 0 °C. The samples were quickly stretched to the prefixed strain and then allowed to relax for 1 h. In every SAXS pattern, the intensity distribution was elongated along the equator, indicating the formation of structures elongated in the stretching direction. The so‐called two‐spots pattern corresponding to the long period of stacked lamellar crystals did not appear even when the critical strain to induce crystallization was exceeded. On the other hand, even below the critical strain, additional development of equatorial streaks was detected in the differential SAXS patterns. This result suggests the growth of the density fluctuation elongated in the stretching direction, which is not directly related to strain‐induced crystallization. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2011
Characteristics of Discontinuous Permafrost based on Ground Temperature Measurements and Electrical Resistivity Tomography, Southern Yukon, Canada
Authors: Lewkowicz Antoni G. , Etzelmüller Bernd , Smith Sharon L. 
Published: June 2011

ABSTRACTWarm permafrost conditions (mean temperatures of −3°C to −0.1°C) were investigated in detail at 13 valley and mountain sites in the sporadic (10–50%) and extensive (50–90%) discontinuous permafrost zones in the southern half of the Yukon (60°N to 64°N), using a combination of ground temperature monitoring, electrical resistivity tomography (ERT), frost table probing and coring. Sites were selected to cover a wide range of substrates, vegetation types and ground ice contents. ERT profiling in the spring imaged both deep seasonal frost and perennially frozen ground. Deep active layers measured by probing at the end of summer were also detectable by ERT. Where ground temperatures indicated that the base of permafrost was at a depth of less than 25 m, vertical transitions in apparent resistivity were more sharply defined in coarse materials than in fine‐grained deposits, probably because of differences in unfrozen moisture contents at temperatures just below 0°C. Apparent resistivity values related to excess ice fraction and ground temperatures were similar to those previously obtained in Mongolia and Iceland, but generally lower than in ice‐rich rock glaciers in European studies. The observations revealed the complexity of site conditions where permafrost is discontinuous and the utility of ERT, in combination with other methods, to investigate permafrost thickness, spatial extent and ice content for infrastructure planning or climate change studies. Copyright © 2011 John Wiley & Sons, Ltd.
Luminescence properties of epitaxially grown GaN and InGaN layers around ZnO nanopillars
Authors: Fikry M. , Madel M. , Tischer I. , Thonke K. , Scholz F. 
Published: June 2011

AbstractGaN and InGaN layers grown around ZnO nanopillars by metalorganic vapour phase epitaxy (MOVPE) are investigated by means of photoluminescence (PL) and locally resolved cathodoluminescence (CL). A multi layer growth process involving deposition at different growth conditions in a step‐wise manner has been employed for the coaxially grown GaN. Then InGaN/GaN quantum wells and barriers have been deposited as the final growth stage. A sharp peak at 3.46 eV in low temperature PL with FWHM of 23 meV confirmed the high quality of the deposited GaN layers. The existence of InGaN layers has been confirmed by another PL peak at 3.16 eV that has been shifted to 3.11 eV as the InGaN deposition temperature was reduced by 15 °C and the trimethylindium (TMIn) flow was increased by 40 sccm. For more efficient investigations of single pillars, position control has been achieved through the growth of single ZnO nanopillars on top of GaN pyramids. Locally resolved CL mapping along single rods has revealed a relatively homogeneous indium distribution along the non‐polar side facets of the overgrown nanopillars.
Polarization‐engineering in group III‐nitride heterostructures: New opportunities for device design
Authors: Jena Debdeep , Simon John , Wang Albert (Kejia) , Cao Yu , Goodman Kevin , Verma Jai , Ganguly Satyaki , Li Guowang , Karda Kamal , Protasenko Vladimir , Lian Chuanxin , Kosel Thomas , Fay Patrick , Xing Huili 
Published: June 2011

AbstractThe role of spontaneous and piezoelectric polarization in III–V nitride heterostructure devices is discussed. Problems as well as opportunities in incorporating polarization in abrupt and graded heterojunctions composed of binary, ternary, and quaternary nitrides are outlined.
Mechanical characterisation of a periodic auxetic structure produced by SEBM
Authors: Schwerdtfeger J. , Schury F. , Stingl M. , Wein F. , Singer R. F. , Körner C. 
Published: June 2011

AbstractWe present a thorough investigation of the mechanical behaviour of a non‐stochastic cellular auxetic structure. A combination of experimental and numerical methods is used to gain a deeper understanding of the mechanical behaviour and its dependence on the geometric properties of the cellular structure. The experimental samples are built from Ti‐6Al‐4V using selective electron beam melting, an additive manufacturing process giving the possibility to vary the geometry of the structure in a highly controlled manner. The use of finite element simulations and mathematical homogenisation allows us also to investigate off‐axis properties of the cellular material. This leads to a more comprehensive understanding of the mechanical behaviour of the auxetics. Ultimately, the gained knowledge can be used to tailor auxetic materials to specific applications.
First‐principles study on half‐metallic properties of CuHg2Ti‐type alloys FeV2Z (Z = Si, Ge, As, Sb)
Authors: Xu Ben , Zhang Ming , Yan Hui 
Published: June 2011

AbstractThe first‐principles calculation within density‐functional theory is used to investigate the electronic structures and magnetic properties in CuHg2Ti‐type alloys FeV2Z (Z = Si, Ge, As, Sb). FeV2Sb is predicted to be half‐metal and the energy gap lies in the majority‐spin bands. Though FeV2Si, FeV2Ge, and FeV2As show no half‐metallicity, their spin polarization of conduction electrons is around 99.7, 99.0, and 97.8%, respectively. The investigation of volume distortion shows that over 99% spin‐polarization can be retained in the range of 5.70–6.05 Å for FeV2Si, 5.85–6.05 Å for FeV2Ge, and 5.90–6.00 Å for FeV2As, respectively. FeV2Sb can keep half‐metallicity from 6.00 to 6.15 Å. We studied the effects of defects at transition‐metal sites and Ge, As, and vacancy substitution for Sb atom on the electronic structures in FeV2Sb, and the results indicate that half‐metallicity in FeV2Sb is not sensitive to substitutions for Sb sites.