bluuebunny/crossref_metadata_2025 huggingface dataset:
Involvement of 15‐lipoxygenase in the inflammatory arthritis
Authors: Wu Ming‐Yueh , Lin Tzu‐Hung , Chiu Yung‐Cheng , Liou Houng‐Chi , Yang Rong‐Sen , Fu Wen‐Mei
Published: February 2012

15‐Lipoxygenase (15‐LOX) is involved in many pathological processes. The aim of this study is to examine the role of 15‐LOX in the matrix metalloproteinase (MMP) expression and inflammatory arthritis. It was found that treatment of 15‐LOX downstream product of 15‐(S)‐HETE (15‐S‐hydroxyeicosatetraenoic acid) increased the mRNA and protein levels of MMP‐2 in rheumatoid arthritis synovial fibroblast (RASF) derived from rheumatoid arthritis patients. The enhancement effect of 15‐(S)‐HETE was antagonized by the addition of LY294002 (PI3K inhibitor) and PDTC (NF‐κB inhibitor). Treatment of 15‐(S)‐HETE increased the phosphorylation of AKT, nuclear translocation of p65 and the breakdown of IκBα. TNF‐α and IL‐1β are the key cytokines involved in arthritis and also increase the activity of MMP‐2 in RASF, which was antagonized by pretreatment with 15‐LOX inhibitor PD146176 or knockdown of 15‐LOX. It was also found that these two cytokines increased the expression of 15‐LOX in RASF. Treatment of glucocorticoid but not NSAIDs inhibited 15‐(S)‐HETE‐induced expression of MMP‐2. In comparison with wild‐type mice, adjuvant‐induced arthritis and MMP‐2 expression in synovial membrane were markedly inhibited in 15‐LOX knockout (KO) mice. These results indicate that 15‐LOX plays an important role in the disease progression of arthritis and may be involved in the inflammatory action induced by TNF‐α and IL‐1β. 15‐LOX is thus a good target for developing drugs in the treatment of inflammatory arthritis. J. Cell. Biochem. 113: 2279–2289, 2012. © 2012 Wiley Periodicals, Inc.
Diffusion‐tensor MRI reveals the complex muscle architecture of the human forearm
Authors: Froeling Martijn , Nederveen Aart J. , Heijtel Dennis F.R. , Lataster Arno , Bos Clemens , Nicolay Klaas , Maas Mario , Drost Maarten R. , Strijkers Gustav J.
Published: February 2012

Purpose:

To design a time‐efficient patient‐friendly clinical diffusion tensor MRI protocol and postprocessing tool to study the complex muscle architecture of the human forearm.

Materials and Methods:

The 15‐minute examination was done using a 3 T system and consisted of: T1‐weighted imaging, dual echo gradient echo imaging, single‐shot spin‐echo echo‐planar imaging (EPI) diffusion tensor MRI. Postprocessing comprised of signal‐to‐noise improvement by a Rician noise suppression algorithm, image registration to correct for motion and eddy currents, and correction of susceptibility‐induced deformations using magnetic field inhomogeneity maps. Per muscle one to five regions of interest were used for fiber tractography seeding. To validate our approach, the reconstructions of individual muscles from the in vivo scans were compared to photographs of those dissected from a human cadaver forearm.

Results:

Postprocessing proved essential to allow muscle segmentation based on combined T1‐weighted and diffusion tensor data. The protocol can be applied more generally to study human muscle architecture in other parts of the body.

Conclusion:

The proposed protocol was able to visualize the muscle architecture of the human forearm in great detail and showed excellent agreement with the dissected cadaver muscles. J. Magn. Reson. Imaging 2012;36:237–248. © 2012 Wiley Periodicals, Inc.
Feasibility of semiquantitative liver perfusion assessment by ferucarbotran bolus injection in double‐contrast hepatic MRI
Authors: Fischer Michael A. , Donati Olivio F. , Reiner Caecilia S. , Hunziker Roger , Nanz Daniel , Boss Andreas
Published: February 2012

Purpose:

To evaluate the feasibility of semiquantitative measurement of liver perfusion from analysis of ferucarbotran induced signal‐dynamics in double‐contrast liver MR‐imaging (DC‐MRI).

Materials and Methods:

In total 31 patients (21 men; 58 ± 10 years) including 18 patients with biopsy proven liver cirrhosis prospectively underwent clinically indicated DC‐MRI at 1.5 Tesla (T) with dynamic T2*‐weighted gradient‐echo imaging after ferucarbotran bolus injection. Breathing artefacts in tissue and input time curves were reduced by Savitzky‐Golay‐filtering and semiquantitative perfusion maps were calculated using a model free approach. Hepatic blood flow index (HBFI) and splenic blood flow index (SBFI) were determined by normalization of arbitrary perfusion values to the perfusion of the erector spinae muscle resulting in a semiquantitative perfusion measure.

Results:

In 30 of 31 patients the evaluated protocol could successfully be applied. Mean HBF was 7.7 ± 2.46 (range, 4.6–12.8) and mean SBF was 13.20 ± 2.57 (range, 8.5–17.8). A significantly lower total HBF was seen in patients with cirrhotic livers as compared to patients with noncirrhotic livers (P < 0.05). In contrast, similar SBF was observed in cirrhotic and noncirrhotic patients (P = 0.11).

Conclusion:

Capturing the signal dynamics during bolus injection of ferucarbotran in DC‐MRI of the liver allows for semiquantitative assessment of hepatic perfusion that may be helpful for a more precise characterisation of liver cirrhosis and focal liver lesions. J. Magn. Reson. Imaging 2012;36:168–176. © 2012 Wiley Periodicals, Inc.
Individualized, multimodal palliative treatment of inoperable esophageal cancer: Clinical impact of photodynamic therapy resulting in prolonged survival
Authors: Lindenmann Joerg , Matzi Veronika , Neuboeck Nicole , Anegg Udo , Baumgartner Eva , Maier Alfred , Smolle Josef , Smolle‐Juettner Freyja Maria
Published: February 2012

Background and Objective

In esophageal carcinoma palliative treatment is often required due to advanced tumor stage or patient‐related factors. The main goal of our retrospective single center study was to evaluate the effect of an individualized multimodal palliative treatment, focusing on the efficacy of different treatment options.

Materials and Methods

Between 1999 and 2009, 640 patients suffering from esophageal carcinoma were referred to our division. Two hundred fifty out of those (39.1%) were treated with palliative intention by using a individualized, multimodal concept including endoscopic dilatation, photodynamic therapy (PDT), endoluminal brachytherapy, external radiation, chemotherapy, stenting, feeding tube, and palliative resection.

Results

There were 37 women (14.9%) and 211 men (85.1%). The treatment included PDT in 171 cases (in 118 as first measure), stenting in 124 (38), dilatation in 83 (24), endoluminal brachytherapy in 92 (20), feeding enterostomy in 40 (14), external radiation in 67 (23), chemotherapy in 57 (29), and palliative resection in 3 patients. The mean number of palliative treatments per patient was 2.6. Mean survival time for the collective was 34 months. Distant metastases and nodal positivity were connected with a significantly reduced survival. If PDT was used in the first place, median survival was 50.9 months compared to 17.3 months if other options were used as initial modality (P = 0.012).

Conclusion

By using an individualized multimodal approach, an acceptable mean survival time can be achieved in advanced esophageal cancer treated with palliative intention. PDT, if used as initial endoluminal treatment in patients without gross tumor infiltration into the mediastinum, the great vessels or the tracheo‐bronchial tree, enables a considerable beneficial effect in the palliative setting. Lasers Surg. Med. 44:189–198, 2012. © 2012 Wiley Periodicals, Inc.
Adolescent Motivations for Reality Television Viewing: An Exploratory Study
Authors: Patino Anthony , Kaltcheva Velitchka D. , Smith Michael F.
Published: February 2012

With the recent growth of reality television programing and its appeal to adolescent viewers, marketers, advertisers, and public policy experts need to understand what motivations drive adolescents to watch reality programs. By understanding adolescent viewer motivations, professionals will be able to craft effective marketing strategies and develop public policy programs for improving the welfare of adolescents. This research involves an exploratory study that examines adolescents’ motivations for watching reality programs through a content analysis of free‐response data from a national sample of 800 adolescents in the United States, members of a Harris Online panel. Theoretical, managerial, and public policy implications of the findings are discussed.
Effects of Mood States on Variety Seeking: The Moderating Roles of Personality
Authors: Chien‐Huang Lin , Hung‐Chou Lin
Published: February 2012

Building upon previous research and in an attempt to better understand the influence of mood states on variety‐seeking (VS) tendency, two specific emotional states (sadness and happiness) are discussed. Furthermore, this article proposes that the effects of mood states on VS are moderated by individuals’ differences. In this article, optimum stimulation level, self‐monitoring, and need for cognition are used to examine the moderating effects of this relationship. Consistent with the proposed hypotheses, the results indicate that sad individuals tend to incorporate more VS than happy ones. In addition, the three personality types tested in this article moderate the effects of mood on VS. Finally, suggestions for future research are discussed.
Oligoaniline‐Containing Supramolecular Block Copolymer Nanodielectric Materials
Authors: Hardy Christopher G. , Islam Md. Sayful , Gonzalez‐Delozier Dioni , Ploehn Harry J. , Tang Chuanbing
Published: February 2012

We report a new generation of nanodielectric energy storage materials based on supramolecular block copolymers. In our approach, highly polarizable, conducting nanodomains are embedded within an insulating matrix through block copolymer microphase separation. An applied electric field leads to electronic polarization of the conducting domains. The high interfacial area of microphase‐separated domains amplifies the polarization, leading to high dielectric permittivity. Specifically, reversible addition fragmentation transfer (RAFT) polymerization was used to prepare block copolymers with poly(methyl acrylate) (PMA) as the insulating segment and a strongly acidic dopant moiety, poly‐(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid) (PAMPSA), as the basis for the conducting segment. The PAMPSA block was complexed with an oligoaniline trimer to form a dopant‐conjugated moiety complex that is electronically conductive after oxidation. For the undoped neat block copolymers, the increase of the PMA block length leads to a transition in dielectric properties from ionic conductor to dielectric capacitor with polarization resulting from migration of protons within the isolated PAMPSA domains. The oligoaniline‐doped copolymers show remarkably different dielectric properties. At frequencies above 200 kHz, they exhibit characteristics of dielectric capacitors with much higher permittivity and lower dielectric loss than the corresponding undoped copolymers.
Short‐term effects of temperature on the abundance and diversity of magnetotactic cocci
Authors: Lin Wei , Wang Yinzhao , Pan Yongxin
Published: February 2012

Temperature is one of the most important climate factors that can regulate the activity and growth of organisms. However, it is so far unclear how temperature influences the abundance and community composition of magnetotactic bacteria (MTB) that mineralize intracellular magnetite and/or greigite magnetosomes and play significant roles in the global iron cycling and sediment magnetization. To address this specific problem, in this study we have assessed the impact of temperature on freshwater magnetotactic cocci through laboratory microcosm simulations. Microcosms containing MTB were exposed to four constant temperatures ranging from 9°C to 37°C. After 10 days and 28 days of incubation, no significant differences in abundance were detected in microcosms at 9°C, 15°C, and 26°C (Student's t‐test, P > 0.05); however, microcosms exposed to 37°C exhibited a significant decrease of magnetotactic cocci abundance (P < 0.05). Dendrogram analysis of community‐amplified ribosomal DNA restriction analysis (community ARDRA) banding patterns distinguished the 37°C samples from samples at lower temperatures regardless of incubation periods. Furthermore, clone library analysis revealed that most of the operational taxonomic units (OTUs) detected in samples from 9°C to 26°C were absent from the 37°C microcosms, whereas six OTUs were exclusively detected in the 37°C samples. Community compositions from four incubation temperatures were further compared using statistical phylogenetic methods (UniFrac and LIBSHUFF), which revealed that the 37°C samples harbored phylogenetically distinct MTB communities compared to those found in 9°C, 15°C, and 26°C samples. Taken together, our results indicate that elevated temperature can influence the abundance and diversity of dominant members of magnetotactic cocci. This linkage further infers that the abundance and diversity of MTB (e.g., based on the fossil magnetosomes) may be useful in reconstruction of paleotemperature.
Gastrointestinal stability and bioavailability of (poly)phenolic compounds following ingestion of Concord grape juice by humans
Authors: Stalmach Angelique , Edwards Christine A. , Wightman JoLynne D. , Crozier Alan
Published: February 2012

The in vitro gastrointestinal stability of (poly)phenolic compounds in Concord grape juice was compared with recoveries in ileal fluid after the ingestion of the juice by ileostomists. Recoveries in ileal fluid indicated that 67% of hydroxycinnamate tartarate esters, and smaller percentages of the intake of other (poly)phenolic compounds, pass from the small intestine to the colon. The juice was also ingested by healthy subjects with an intact functioning colon. Peak plasma concentrations (Cmax) ranged from 1.0 nmol/L for petunidin‐3‐O‐glucoside to 355 nmol/L for dihydrocoumaric acid. Urinary excretion, as an indicator of bioavailability, varied from 0.26% for total anthocyanins to 24% for metabolites of hydroxycinnamate tartarate esters. The Cmax times of the anthocyanins indicated that their low level absorption occurred in the small intestine in contrast to hydroxycinnamate metabolites which were absorbed in both the small and the large intestine where the colonic microflora appeared responsible for hydrogenation of the hydroxycinnamate side chain. The bioavailability of the complex mixture of (poly)phenolic compounds in Concord grape juice, was very similar to that observed in previous studies when compounds were either fed individually or as major components in products containing a restricted spectrum of (poly)phenolic compounds.
Metabolite kinetics in C6 rat glioma model using magnetic resonance spectroscopic imaging of hyperpolarized [1‐13C]pyruvate
Authors: Park Jae Mo , Josan Sonal , Jang Taichang , Merchant Milton , Yen Yi‐Fen , Hurd Ralph E. , Recht Lawrence , Spielman Daniel M. , Mayer Dirk
Published: February 2012

In addition to an increased lactate‐to‐pyruvate ratio, altered metabolism of a malignant glioma can be further characterized by its kinetics. Spatially resolved dynamic data of pyruvate and lactate from C6‐implanted female Sprague–Dawley rat brain were acquired using a spiral chemical shift imaging sequence after a bolus injection of a hyperpolarized [1‐13C]pyruvate. Apparent rate constants for the conversion of pyruvate to lactate in three different regions (glioma, normal appearing brain, and vasculature) were estimated based on a two‐site exchange model. The apparent conversion rate constant was 0.018 ± 0.004 s−1 (mean ± standard deviation, n = 6) for glioma, 0.009 ± 0.003 s−1 for normal brain, and 0.005 ± 0.001 s−1 for vasculature, whereas the lactate‐to‐pyruvate ratio, the metabolic marker used to date to identify tumor regions, was 0.36 ± 0.07 (mean ± SD), 0.24 ± 0.07, and 0.12 ± 0.02 for glioma, normal brain, and vasculature, respectively. The data suggest that the apparent conversion rate better differentiate glioma from normal brain (P = 0.001, n = 6) than the lactate‐to‐pyruvate ratio (P = 0.02). Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.
Model‐based mapping of fat unsaturation and chain length by chemical shift imaging—phantom validation and in vivo feasibility
Authors: Berglund Johan , Ahlström Håkan , Kullberg Joel
Published: February 2012

Knowledge about the triglyceride (fat) 1H spectrum enables quantitative determination of several triglyceride characteristics. This work describes a model‐based chemical shift imaging method that separates water and fat signal and provides maps of three triglyceride quantities: fatty acid carbon chain length, unsaturation degree, and polyunsaturation degree. The method was validated by imaging a phantom containing 10 different oils using 1.5 and 3.0 T clinical scanners, with gas–liquid chromatography as reference. Repeated acquisitions demonstrated high reproducibility of the method. Statistical tests of correlation and linear regression were performed to examine the accuracy of the method. Significant correlation was found at both field strengths for all three quantities, and high correlation (r2 > 0.95) was found for measuring unsaturation degree and polyunsaturation degree. Feasibility of the method for in vivo imaging of the thigh was demonstrated at both field strengths. The estimates of unsaturation degree and polyunsaturation degree in subcutaneous adipose tissue were in agreement with literature values, while chain length appeared over estimated. The method has potential use in large‐scale cross‐sectional and longitudinal studies of triglyceride composition, and its relation to diet and various diseases. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.
A method to determine the necessity for global signal regression in resting‐state fMRI studies
Authors: Chen Gang , Chen Guangyu , Xie Chunming , Ward B. Douglas , Li Wenjun , Antuono Piero , Li Shi‐Jiang
Published: February 2012

In resting‐state functional MRI studies, the global signal (operationally defined as the global average of resting‐state functional MRI time courses) is often considered a nuisance effect and commonly removed in preprocessing. This global signal regression method can introduce artifacts, such as false anticorrelated resting‐state networks in functional connectivity analyses. Therefore, the efficacy of this technique as a correction tool remains questionable. In this article, we establish that the accuracy of the estimated global signal is determined by the level of global noise (i.e., non‐neural noise that has a global effect on the resting‐state functional MRI signal). When the global noise level is low, the global signal resembles the resting‐state functional MRI time courses of the largest cluster, but not those of the global noise. Using real data, we demonstrate that the global signal is strongly correlated with the default mode network components and has biological significance. These results call into question whether or not global signal regression should be applied. We introduce a method to quantify global noise levels. We show that a criteria for global signal regression can be found based on the method. By using the criteria, one can determine whether to include or exclude the global signal regression in minimizing errors in functional connectivity measures. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.
Fast volumetric imaging of ethanol metabolism in rat liver with hyperpolarized [1‐13C]pyruvate
Authors: Josan Sonal , Spielman Daniel , Yen Yi‐Fen , Hurd Ralph , Pfefferbaum Adolf , Mayer Dirk
Published: February 2012

Rapid volumetric imaging of hyperpolarized 13C compounds allows the real‐time measurement of metabolic activity and can be useful in distinguishing between normal and diseased tissues. This work extends a fast two‐dimensional undersampled spiral MRSI sequence to provide volumetric coverage, acquiring a 16 × 16 × 12 matrix with a nominal isotropic resolution of 5 mm in 4.5 s. The rapid acquisition enables a high temporal resolution for dynamic imaging. This dynamic three‐dimensional MRSI method was used to investigate hyperpolarized [1‐13 C]pyruvate metabolism modulated by the administration of ethanol in rat liver. A significant increase in the pyruvate to lactate conversion was observed in the liver as a result of the greater availability of NADH (nicotinamide adenine dinucleotide, reduced form) from ethanol metabolism. Copyright © 2012 John Wiley & Sons, Ltd.
The preconditioned inverse iteration for hierarchical matrices
Authors: Benner Peter , Mach Thomas
Published: February 2012

The preconditioned inverse iteration is an efficient method to compute the smallest eigenpair of a symmetric positive definite matrix M. Here we use this method to find the smallest eigenvalues of a hierarchical matrix. The storage complexity of the data‐sparse ‐matrices is almost linear. We use ‐arithmetic to precondition with an approximate inverse of M or an approximate Cholesky decomposition of M. In general, ‐arithmetic is of linear‐polylogarithmic complexity, so the computation of one eigenvalue is cheap. We extend the ideas to the computation of inner eigenvalues by computing an invariant subspace S of (M − μI)2 by subspace preconditioned inverse iteration. The eigenvalues of the generalized matrix Rayleigh quotient μM(S) are the desired inner eigenvalues of M. The idea of using (M − μI)2 instead of M is known as the folded spectrum method. As we rely on the positive definiteness of the shifted matrix, we cannot simply apply shifted inverse iteration therefor. Numerical results substantiate the convergence properties and show that the computation of the eigenvalues is superior to existing algorithms for non‐sparse matrices.Copyright © 2012 John Wiley & Sons, Ltd.
Numerical simulation of flapping wings using a panel method and a high‐order Navier–Stokes solver
Authors: Persson P.‐O. , Willis D.J. , Peraire J.
Published: February 2012

The design of efficient flapping wings for human engineered micro aerial vehicles (MAVs) has long been an elusive goal, in part because of the large size of the design space. One strategy for overcoming this difficulty is to use a multifidelity simulation strategy that appropriately balances computation time and accuracy. We compare two models with different geometric and physical fidelity. The low‐fidelity model is an inviscid doublet lattice method with infinitely thin lifting surfaces. The high‐fidelity model is a high‐order accurate discontinuous Galerkin Navier–Stokes solver, which uses an accurate representation of the flapping wing geometry. To compare the performance of the two methods, we consider a model flapping wing with an elliptical planform and an analytically prescribed spanwise wing twist, at size scales relevant to MAVs. Our results show that in many cases, including those with mild separation, low‐fidelity simulations can accurately predict integrated forces, provide insight into the flow structure, indicate regions of likely separation, and shed light on design–relevant quantities. But for problems with significant levels of separation, higher‐fidelity methods are required to capture the details of the flow field. Inevitably high‐fidelity simulations are needed to establish the limits of validity of the lower fidelity simulations.Copyright © 2012 John Wiley & Sons, Ltd.
Interest mobilization in public health and social insurance: Argentina, Colombia, and Mexico in comparative perspective
Authors: Brachet‐Márquez Viviane , Alonso Guillermo V. , Uribe Gómez Mónica
Published: February 2012

One revealing test for gauging the extent to which pluralist democracy has advanced in the recently (re)democratized countries of Latin America is to determine the extent to which interest groups have come to participate in policy making in formal, open, extensive, and accepted ways as they mostly do in advanced liberal democracies. In other words, is this a new era or more of the same? To provide insights into this question, using six hypotheses, this article compares social insurance reform in Argentina and Mexico, and public health reform in Colombia.

It appears that the political processes through which the reforms were adopted were fairly democratic, although aspects of the old regimes in all three countries, particularly corporatist relationships, were indispensable backups. The weaknesses that were apparent, however, stem less from the old ways of doing political business and more from the immaturity of the democratic process. Plus, pressures were felt by the executive branches and their allies to show to the international community that their country was a safe place in which to invest. Copyright © 2012 John Wiley & Sons, Ltd.
Religious/spiritual coping resources and their relationship with adjustment in patients newly diagnosed with breast cancer in the UK
Authors: Thuné‐Boyle Ingela C. V. , Stygall Jan , Keshtgar Mohammed R. S. , Davidson Tim I. , Newman Stanton P.
Published: February 2012

Background

Religious/spiritual resources may serve multiple functions in adjustment to cancer. However, there is very little evidence of the importance of religious/spiritual variables outside the USA. This paper reports the cross‐sectional data of a longitudinal study examining the beneficial and harmful effects of religious/spiritual coping resources on adjustment in the first year after a breast cancer diagnosis.

Method

One hundred and fifty‐five patients newly diagnosed with breast cancer were assessed after surgery. Several aspects of religiousness/spirituality in relation to anxiety and depression were examined: religiosity/spirituality, strength of faith, belief in God, private and public practices, spiritual involvement, perceived spiritual support and positive and negative religious coping strategies. Non‐religious coping, social support and optimism were also assessed.

Results

‘Feeling punished and abandoned by God’ significantly explained 5% of the variance in increased levels of anxiety but was partially mediated by denial coping. It was also partially mediated by acceptance coping, lowering levels of anxiety. Feeling punished and abandoned by God was a significant independent predictor of depressed mood, explaining 4% of the variance.

Conclusion

Using religious/spiritual resources in the coping process during the early stages of breast cancer may play an important role in the adjustment process in patients with breast cancer. Patients may benefit from having their spiritual needs addressed as experiencing some form of religious/spiritual struggle may serve as a barrier to illness adjustment. Implications for research and clinical practices are discussed. Copyright © 2012 John Wiley & Sons, Ltd.
Research Perspectives on Unstable High‐alpine Bedrock Permafrost: Measurement, Modelling and Process Understanding
Authors: Krautblatter Michael , Huggel Christian , Deline Philip , Hasler Andreas
Published: February 2012

Rock instability is believed to be causally linked to permafrost degradation, but it is difficult to demonstrate this directly because of the short record of slope failures in high mountains. While abductive scientific reasoning of ‘increasing permafrost‐related instability’ based on the short time frame of recorded rockfall events in high mountains is still difficult, our deductive systemic understanding points toward a strong process linkage between permafrost degradation and rock instability. Enhanced technical understanding of coupled thermo‐hydro‐mechanical processes and systemic geomorphic understanding of rock slope adjustment in space and over (reaction/relaxation) time are required to accurately predict hazards associated with the impact of climate change on permafrost in bedrock. We identify research needs in four major areas and at the interfaces between them: rock temperature measurement and modelling; remote sensing of rock walls; process understanding of rock mass instability; and flow propagation models of rock‐ice avalanches. This short communication identifies key interfaces between research directions to gain a better understanding of trajectories of destabilisation in time and space. We propose coordinated systemic research with respect to scale dependent and transient thermal behaviour, coupled thermo‐hydro‐mechanical understanding, enhanced remote inventorying of rock wall instability and integrated approaches for a better understanding and modelling of mixed avalanches. Copyright © 2012 John Wiley & Sons, Ltd.
Crystal structure of vinculin in complex with vinculin binding site 50 (VBS50), the integrin binding site 2 (IBS2) of talin
Authors: Yogesha S. D. , Rangarajan Erumbi S. , Vonrhein Clemens , Bricogne Gerard , Izard Tina
Published: February 2012

The cytoskeletal protein talin activates integrin receptors by binding of its FERM domain to the cytoplasmic tail of β‐integrin. Talin also couples integrins to the actin cytoskeleton, largely by binding to and activating the cytoskeletal protein vinculin, which binds to F‐actin through the agency of its five‐helix bundle tail (Vt) domain. Talin activates vinculin by means of buried amphipathic α‐helices coined vinculin binding sites (VBSs) that reside within numerous four‐ and five‐helix bundle domains that comprise the central talin rod, which are released from their buried locales by means of mechanical tension on the integrin:talin complex. In turn, these VBSs bind to the N‐terminal seven‐helix bundle (Vh1) domain of vinculin, creating an entirely new helix bundle that severs its head‐tail interactions. Interestingly, talin harbors a second integrin binding site coined IBS2 that consists of two five‐helix bundle domains that also contain a VBS (VBS50). Here we report the crystal structure of VBS50 in complex with vinculin at 2.3 Å resolution and show that intramolecular interactions of VBS50 within IBS2 are much more extensive versus its interactions with vinculin. Indeed, the IBS2‐vinculin interaction only occurs at physiological temperature and the affinity of VBS50 for vinculin is about 30 times less than other VBSs. The data support a model where integrin binding destabilizes IBS2 to allow it to bind to vinculin.
Thermal coefficients of the methyl groups within ubiquitin
Authors: Sabo T. Michael , Bakhtiari Davood , Walter Korvin F. A. , McFeeters Robert L. , Giller Karin , Becker Stefan , Griesinger Christian , Lee Donghan
Published: February 2012

Physiological processes such as protein folding and molecular recognition are intricately linked to their dynamic signature, which is reflected in their thermal coefficient. In addition, the local conformational entropy is directly related to the degrees of freedom, which each residue possesses within its conformational space. Therefore, the temperature dependence of the local conformational entropy may provide insight into understanding how local dynamics may affect the stability of proteins. Here, we analyze the temperature dependence of internal methyl group dynamics derived from the cross‐correlated relaxation between dipolar couplings of two CH bonds within ubiquitin. Spanning a temperature range from 275 to 308 K, internal methyl group dynamics tend to increase with increasing temperature, which translates to a general increase in local conformational entropy. With this data measured over multiple temperatures, the thermal coefficient of the methyl group order parameter, the characteristic thermal coefficient, and the local heat capacity were obtained. By analyzing the distribution of methyl group thermal coefficients within ubiquitin, we found that the N‐terminal region has relatively high thermostability. These results indicate that methyl groups contribute quite appreciably to the total heat capacity of ubiquitin through the regulation of local conformational entropy.
Control of polarized emission from selectively etched GaN/AlN quantum dot ensembles on Si(111)
Authors: Rich Daniel H. , Moshe Ofer , Damilano Benjamin , Massies Jean
Published: February 2012

Multiple layers of GaN/AlN quantum dot (QD) ensembles were grown by the Stranski‐Krastanov method on Si(111) using molecular beam epitaxy. During the subsequent cooling from growth temperature, the thermal expansion coefficient mismatch between the Si substrate and GaN/AlN film containing the vertically stacked QDs leads to an additional biaxial tensile stress of 20–30 kbar in the III‐nitride film. We have selectively modified the thermal stress in the QD layers by etching a cross‐hatched pattern into the as‐grown sample using inductively coupled Cl2/Ar plasma reactive ion etching. The results show that a suitable choice of stripe width from ∼2 to 10 μm and orientation along [11‐20] and [1‐100] can create regions of in‐plane uniaxial stress that enable a selective and local control of the polarized luminescence from ensembles of QDs which were probed with cathodoluminescence. A theoretical modelling of the effects of carrier filling on the polarization anisotropy and the excitonic transition energy was performed, as based on three dimensional self‐consistent solutions of the Schrödinger and Poisson equations using the 6 × 6 k·p method (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrical properties of MBE grown Si3N4–cubic GaN MIS structures
Authors: Zado A. , Lischka K. , As D. J.
Published: February 2012

In this work we report on the electrical characterization of non‐polar cubic GaN metal‐insulator‐semiconductor (MIS) structures. Si3N4 layers were deposited in‐situ on top of cubic GaN grown on 3C‐SiC (001) substrates. The electric characteristics of the MIS structures are measured by capacitance and admittance spectroscopy techniques. From the hysteresis in the capacitance‐voltage curves and the peak height of the conductance Gp –ω frequency curves the interface state densities are calculated.

We find interface traps about 0.3 eV below the conduction band. The density of these traps is Dit = 2.5x1011 cm‐2eV‐1. This is one order of magnitude lower than in MIS structures with a Si3N4 insulator produced by plasma enhanced vapour deposition and two orders of magnitude lower than in MIS structures on c‐GaN with SiO2 as insulator (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of substrate biasing on the growth of c‐axis oriented AlN thin films by RF reactive sputtering in pure nitrogen
Authors: Monteagudo‐Lerma L. , Naranjo F. B. , González‐Herráez M. , Fernández S.
Published: February 2012

We report on the investigation of the influence of deposition conditions on structural, morphological and optical properties of AlN thin films deposited on sapphire (Al2O3) substrates by radio‐frequency (RF) reactive sputtering. The deposition parameters studied are RF power, substrate temperature and substrate bias, while using pure nitrogen as reactive gas. The effect of such deposition parameters on AlN film properties are analyzed by different characterization methods as high resolution X‐ray diffraction (HRXRD), field emission scanning electron microscopy (FESEM) and linear optical transmission. AlN thin films with a full‐width at half‐maximum (FWHM) of the rocking curve obtained for the (0002) diffraction peak of 1.2º are achieved under optimized conditions. The time resolved evolution of the self and externally‐induced biasing of the substrate during deposition process is monitored and analyzed in terms of the rate of atomic species incorporation into the layer. The bias‐induced change of the atomic incorporation leads to an enhancement in the structural quality of the layer and an increase of the deposition rate. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of neutron irradiation and annealing on the optical properties of GaN
Authors: Rodrigues J. , Peres M. , Soares M. J. , Lorenz K. , Marques J. G. , Neves A. J. , Monteiro T.
Published: February 2012

Epitaxial GaN layers were irradiated with fast and thermal neutrons in the Portuguese Research Reactor. Irradiation leads to a quenching of the typical GaN near band edge and yellow luminescence for samples excited with above band gap photon energy. Although structural techniques indicate a full recovery of irradiation damage for annealing at 1000 °C, the near band edge emission is not recovered after annealing. Nevertheless, deep level recombination is detected with above and below band gap excitation. In particular, the yellow and green luminescence bands (at 2.2 and 2.35 eV) are observed upon above band gap excitation while under illumination with below the band gap energy a yellow luminescence at 2.1 eV and infrared unstructured bands at 1.2 eV and 1.0 eV are observed The position of below gap broad bands is strongly dependent on the irradiation conditions and annealing pointing to the formation of distinctly different defect complexes or different charge states of optically active defects (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Equivalent‐circuit‐model for GaN‐GIT bi‐directional switch including influence of gate resistance
Authors: Ide Toshihide , Shimizu Mitsuaki , Shen Xu‐Qiang , Morita Tatsuo , Ueda Tetsuzo , Tanaka Tsuyoshi
Published: February 2012

We obtain an equivalent‐circuit‐model for GaN gate‐insulated‐transistor (GIT) bi‐directional switches (BDSWs) which consists of one current source and three capacitances. Employing this model for the chopper circuit simulation, the gate resistance dependence is included into the input capacitance of CG1S2 and CG1S1 in order to improve the accuracy. By including this influence of the gate resistance, the calculated waveforms and the estimated switching losses agree well with the experimental ones with accuracy of over 90% when the circuit conditions are varied. This gate resistance dependence is considered to be caused by the hole injection at the gate region. By using our proposed model, this equivalent‐circuit‐model for GIT BDSWs can be treated with like a simple single‐gate MOSFET model (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth of crack‐free GaN epitaxial thin films on composite Si(111)/polycrystalline diamond substrates by MOVPE
Authors: Jiang Quanzhong , Edwards Michael J. , Shields Philip A. , Allsopp Duncan W. E. , Bowen Christopher R. , Wang Wang N. , Tóth Lajos , Pécz Bela , Srnanek Rudolf , Satka Alexander , Kovac Jaroslav
Published: February 2012

This paper reports the direct growth by MOVPE of high‐quality, crack‐free III‐nitrides (∼350 nm) on composite substrates comprising an ultra‐thin Si (111) layer on which polycrystalline diamond (PD) has been deposited. The Si/PD substrates are designed to provide superior heat sinking performance for high power devices. The FWHM of rocking curves of the nitride films is measured to be ∼1100 arcsec from a GaN/Al0.2Ga0.8N/AlN/Si/PD multilayer structure. As expected from the low coefficient of thermal expansion of diamond, the epitaxial layers are under severe tensile stress. The Si (111) layer is shown to act as a compliant buffer layer between the III‐nitride and the PD, i.e. the Si is under a compressive stress under the influence of GaN of larger thermal expansion coefficient, but the structure is mechanically stable. This technique is an obvious economic and technological advantage compared to direct growth of III‐nitrides on single crystal diamond (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
New less‐conservative stability results for uncertain stochastic neural networks with fewer slack variables
Authors: Zheng Cheng‐De , Zhang Huaguang , Wang Zhanshan
Published: February 2012

The exponential stability problem is investigated for a class of uncertain stochastic neural networks with discrete and unbounded distributed time delays. Two types of uncertainty are considered: one is time‐varying structured uncertainty, whereas the other is interval uncertainty. With the application of the Jensen integral inequality and constructing appropriate Lyapunov–Krasovskii functional based on delay partitioning, several improved delay‐dependent criteria are developed to achieve the exponential stability in mean square in terms of linear matrix inequalities. It is established theoretically that two special cases of the obtained criteria are less conservative than some existing results but including fewer slack variables. As the present conditions involve fewer free weighting matrices, the computational burden is largely reduced. Three numerical examples are provided to demonstrate the effectiveness of the theoretical results. Copyright © 2012 John Wiley & Sons, Ltd.
Contributions to model validation: hierarchy, process, and cessation
Authors: Groesser Stefan N. , Schwaninger Markus
Published: February 2012

In the domain of dynamic modeling and simulation, the assurance of model validity is a prominent challenge. An extensive number of contributions concerning model tests, terminology, and the epistemological foundations of validation have been elaborated. These contributions, however, do not fully answer the questions for novice modelers, namely, which validation tests to choose, when and how to apply them, and at what point to cease their formal validation efforts. Our intention here is to help close this gap by introducing a complexity hierarchy of validation tests, an integrative validation process, and a decision heuristic about when to stop formal validation efforts. The paper concludes by providing directions for future research. Copyright © 2012 System Dynamics Society
Low‐Field Magnetoresistance Effect in Core–Shell Structured La0.7Sr0.3CoO3 Nanoparticles
Authors: Wang Yang , Fan Hong Jin
Published: February 2012

Core–shell structured La0.7Sr0.3CoO3 nanoparticles are synthesized and their magnetic and magneto‐transport properties are investigated. In these core–shell La0.7Sr0.3CoO3 nanoparticles, the cores are single‐crystalline and ferromagnetic, whereas the shells are noncrystalline and predominantly paramagnetic. Moreover, the insulating‐like shells can serve as a good spin tunneling barrier. Therefore, in such a special core–shell structure, the spin‐polarized interparticle tunneling is improved due to the existence of shells, which thus induces an enhanced low‐field magnetoresistance effect.
Learning from Conflict Resolution: An Opportunity to Systems Thinking
Authors: Li Ya , Zhu Zhichang , Gerard Catherine M.
Published: February 2012

Systems thinking (ST) and conflict resolution (CR) have much to gain from mutual informing and learning. This review article attempts to introduce the systems community to the research and practice of CR. It outlines the strands, development and frontiers of CR and analyzes its relevance to and similarities with ST. The article then discusses the implications for further systems research. Copyright © 2012 John Wiley & Sons, Ltd.
Hybrid steel plate girders subjected to patch loading
Authors: Bock Marina , Chacón Rolando , Mirambell Enrique , Real Esther
Published: February 2012

Hybrid girders represent an economical alternative to homogeneous girders because they achieve greater flexural capacity with less material. One of the potential applications of hybrid steel plate girders is their use in bridges. One potential method of construction for these bridges is the push launch method in which patch loading may affect the design. The aim of this paper is to present the advanced conclusions of research work dealing with these two fields simultaneously: hybrid steel plate girders subjected to the particular case of patch loading. It is shown that, contrary to the EN 1993‐1‐5 formulation, the influence of the fyf /fyw ratio (namely, the hybrid grade) is negligible for both unstiffened and longitudinally stiffened girders according to the EN 1993‐1‐5 assumptions. Suggestions for considering these findings in design codes are provided at the end of the paper.
Statistical evaluation of the new resistance model for steel plate girders subjected to patch loading
Authors: Mirambell Enrique , Chacón Rolando , Kuhlmann Ulrike , Braun Benjamin
Published: February 2012

This paper presents a new resistance model for steel plate girders subjected to patch loading. The model aims to correct the EN 1993‐1‐5 formulation concerning the resistance to transverse forces with the help of findings presented in several doctoral studies on this topic. In addition, a statistical calibration of the new model is addressed. This calibration includes a new proposal for the resistance function χ‐λ. The proposal is conceived for fulfilling safety levels of the partial safety factor that match the current values included in EN 1993 for instability‐related problems. These new proposals are in accordance with the design philosophy found in EN 1993‐1‐5 for the design of plated structures.
New efficient cross‐layer and multihoming mechanisms at layer 2 for inter‐radio access technology handover between UMTS and WiMAX
Authors: Liu Bin , Boukhatem Nadia , Martins Philippe , Bertin Philippe
Published: February 2012

Next generation mobile networks will provide seamless mobility between existing cellular systems and other wireless access technologies. To realize a seamless vertical handover (inter‐radio access technology handover) among these different access technologies, a multi‐interfaced mobile station (i.e., multihomed) is a good approach to provide better handover performance in terms of packet loss rate and handover latency. In this article, we propose a novel layer 2 multihoming approach for inter‐radio access technology handover between Universal Mobile Telecommunications System (UMTS) and Worldwide Interoperability for Microwave Access (WiMAX) in both integrated and tight coupling architectures. This layer 2 multihoming approach has the ability of enabling either soft handover or make‐before‐break handover to adapt to mobility scenarios for the sake of a lossless and short latency handover procedure. Our simulation results show that, in case of handover from UMTS to WiMAX for transmission control protocol (TCP) traffics, the layer 2 multihoming approach can achieve a lossless and zero latency handover procedure by enabling soft handover. In case of handover from WiMAX to UMTS, because of the fact that the performance gain of soft handover is more affected by the differences of bandwidth and transmission delay between these wireless links, the make‐before‐break handover is preferred to achieve lossless and short latency handover procedure. Copyright © 2012 John Wiley & Sons, Ltd.
Explaining the functional differences of rods versus cones
Authors: Kawamura Satoru , Tachibanaki Shuji
Published: February 2012

Our visual sensation is mediated by two types of photoreceptors, rods and cones. Both respond to light electrically. Rods are highly light‐sensitive but cones are not. Because of this sensitivity difference, rods mediate night vision and cones mediate daylight vision. While a response to a brief light flash is rather slow in rods, it is brief in cones. These rod and cone differences in their light sensitivity and the response time course arise in the differences in the reactions in the enzyme cascade to evoke light responses in these cells. This cascade (phototransduction cascade) in rods is now rather well understood at the molecular level in a quantitative way. In cones, similar cascade has been known to be present. However, details are not known yet because it was difficult to obtain purified cones in an amount large enough to study these issues biochemically. Fortunately, we succeeded in the purification of enough amounts of cones from the retina of carp (Cyprinus carpio), which enables us to compare the qualitative and quantitative differences in the phototransduction cascade between rods and cones. The results so far we obtained explain lower light sensitivity and briefer light responses in cones than in rods. Furthermore, an additional difference between rods and cones was found in the retinoid metabolism. This reaction, specifically found in cones, ensures effective regeneration of visual pigment so that cones can operate even under very bright light. WIREs Membr Transp Signal 2012, 1: 675–683. doi: 10.1002/wmts.8

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