bluuebunny/crossref_metadata_2025 huggingface dataset:
Polarization induced doping in graded AlGaN films
Authors: Li Shibin , Ware Morgan E. , Kunets Vasyl P. , Hawkridge Mike , Minor Paul , Wu Jiang , Salamo Gregory J.
Published: June 2011

Here, we report on initial experiments to use the space charge of the changing internal polarization field from graded AlGaN films in a simple p‐n junction device. Our devices are fabricated from films which are graded from GaN to AlGaN then reverse graded back to GaN without the intentional addition of impurity dopants. Structural characterization of the films is reported through X‐Ray diffraction, reciprocal space maps, and temperature dependent I‐V measurements are used to demonstrate the rectifying behaviour of the device (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Self‐Assembly of Hydrophilic Homopolymers: A Matter of RAFT End Groups
Authors: Du Jianzhong , Willcock Helen , Patterson Joseph P. , Portman Ian , O'Reilly Rachel K.
Published: June 2011

Unusual self‐assembly behavior is observed for a range of hydrophilic homopolymers. This self‐assembly behavior is contrary to the expected behavior of such hydrophilic polymers and instead mimics more commonly reported amphiphilic block copolymers. It is proposed that the unique combination of hydrophobic end groups at both the α and ω chain end accounts for this unusual self‐assembly behavior. Complex internal polymer micelles are spontaneously formed when hydrophilic homopolymer polyelectrolytes and neutral polymers (with a weight fraction of the hydrophobic end groups <10 wt%) are directly dissolved in water. The homopolymers, poly[2‐(diethylamino)ethyl methacrylate], poly(N‐isopropylacrylamide), and poly(ethoxyethylacrylate) are synthesized by reversible addition–fragmentation chain‐transfer (RAFT) polymerization using S′‐1‐dodecyl‐(S′)‐(α,α′‐dimethyl‐α″‐acetic acid) trithiocarbonate (DDMAT) and its derivatives as chain transfer agents (CTAs). A range of polyelectrolyte homopolymers with different terminal groups are designed and synthesized, which under acidic aqueous solution direct the self‐assembly to form well‐defined nanostructures. This assembly behavior was also observed for neutral polymers, and it was determined that the structure of the hydrophobic end groups (and thus choice of RAFT CTA) are very important in facilitating this unusual self‐assembly behavior of hydrophilic homopolymers. It is proposed that the functionality of commonly used CTAs such as DDMAT, can affect the solution association of the resultant homopolymers and can in fact afford ABA′ type polymers, which can undergo self‐assembly to form higher‐order nanostructures.
Dura Mater Stimulates Human Adipose-Derived Stromal Cells to Undergo Bone Formation in Mouse Calvarial Defects
Authors: Levi Benjamin , Nelson Emily R. , Li Shuli , James Aaron W. , Hyun Jeong S. , Montoro Daniel T. , Lee Min , Glotzbach Jason P. , Commons George W. , Longaker Michael T.
Published: June 2011

Human adipose-derived stromal cells (hASCs) have a proven capacity to aid in osseous repair of calvarial defects. However, the bone defect microenvironment necessary for osseous healing is not fully understood. In this study, we postulated that the cell-cell interaction between engrafted ASCs and host dura mater (DM) cells is critical for the healing of calvarial defects. hASCs were engrafted into critical sized calvarial mouse defects. The DM-hASC interaction was manipulated surgically by DM removal or by insertion of a semipermeable or nonpermeable membrane between DM and hASCs. Radiographic, histologic, and gene expression analyses were performed. Next, the hASC-DM interaction is assessed by conditioned media (CM) and coculture assays. Finally, bone morphogenetic protein (BMP) signaling from DM was investigated in vivo using novel BMP-2 and anti-BMP-2/4 slow releasing scaffolds. With intact DM, osseous healing occurs both from host DM and engrafted hASCs. Interference with the DM-hASC interaction dramatically reduced calvarial healing with abrogated BMP-2–Smad-1/5 signaling. Using CM and coculture assays, mouse DM cells stimulated hASC osteogenesis via BMP signaling. Through in vivo manipulation of the BMP-2 pathway, we found that BMP-2 plays an important role in DM stimulation of hASC osteogenesis in the context of calvarial bone healing. BMP-2 supplementation to a defect with disrupted DM allowed for bone formation in a nonhealing defect. DM is an osteogenic cell type that both participates in and stimulates osseous healing in a hASC-engrafted calvarial defect. Furthermore, DM-derived BMP-2 paracrine stimulation appears to play a key role for hASC mediated repair.
Brief Report: Evaluating the Potential of Putative Pluripotent Cells Derived from Human Testis
Authors: Ko Kinarm , Reinhardt Peter , Tapia Natalia , Schneider Rebekka K. , Araúzo-Bravo Marcos J. , Han Dong Wook , Greber Boris , Kim Julee , Kliesch Sabine , Zenke Martin , Schöler Hans R.
Published: June 2011

Human adult germline stem cells (haGSCs) were established from human testicular biopsies and were claimed to be pluripotent. Recently, the gene expression profile of haGSCs demonstrated that these cells presented with a fibroblast rather than a pluripotent identity. Nevertheless, haGSCs were reported to generate teratomas. In this report, we address this discrepancy. Instead of using haGSCs, which are no longer available for the stem cell community, we used a human testicular fibroblastic cell (hTFC) line that presents with a gene expression profile highly similar to that of haGSCs. Indeed, as shown by microarray analysis, the similarity between hTFCs and haGSCs is comparable to human embryonic stem cell (hESC) lines derived by different laboratories. We argue that the almost identical gene expression profile of hTFCs and haGSCs should result in a very similar if not identical differentiation potential. Strikingly, hTFCs were not able to generate teratomas after injection into nude mice. Instead, they formed a mesenchymal lesion that morphologically resembled the putative haGSC-derived teratomas reported previously. We conclude that haGSCs, which exhibit a profile similar to that of fibroblasts and could not generate teratomas, are not pluripotent. Future work will have to show if pluripotent cells can be derived from human testicular biopsies. Mouse work and certain testicular germ cell tumors indicate that this will be possible.
Mitigating subsynchronous resonance and damping power system oscillation in a series compensated wind park using a novel static synchronous series compensator control algorithm
Authors: El‐Moursi Mohamed S.
Published: June 2011

This paper presents a novel damping control algorithm for static synchronous series compensator (SSSC) in a series compensated wind park for mitigating subsynchronous resonance (SSR) and for damping power system oscillations. The sample test system, adapted from the IEEE first benchmark model on SSR replacing the synchronous generator, is employed aggregating wind park based self‐excited induction generator. Consequently, it investigates the SSR phenomena and the damping power system oscillation while integrating large wind park based on SEIG. The potential occurrence and mitigation of the SSR caused by induction generator effects as well as torsional interactions, in a series compensated wind park, are investigated. The auxiliary subsynchronous damping control loops for the SSSC based on a novel design procedure of non‐linear optimization are developed. The performance of the controller is tested in steady state operation and in response to system contingencies, taking into account the impact of short circuit ratios (SCRs). The simulation results are presented to demonstrate the capability of the controllers for mitigating the SSR, damping the power system oscillation and enhancing the transient stability margin in response to different SCRs. Copyright © 2011 John Wiley & Sons, Ltd.
A high dietary concentration of inulin is necessary to reduce the incidence of swine dysentery in pigs experimentally challenged withBrachyspira hyodysenteriae
Authors: Hansen Christian F. , Hernández Aracely , Mansfield Josie , Hidalgo Álvaro , La Tom , Phillips Nyree D. , Hampson David J. , Pluske John R.
Published: June 2011

A total of sixty surgically castrated male pigs (Large White × Landrace) weighing 31·2 (sd4·3) kg were used in a randomised block experiment to examine the effect of added dietary inulin (0, 20, 40 and 80 g/kg) on the occurrence of swine dysentery (SD) and on fermentation characteristics in the large intestine after experimental challenge with the causative spirochaeteBrachyspira hyodysenteriae. The pigs were allowed to adapt to the diets for 2 weeks before each pig was challenged orally four times with a broth culture containingB. hyodysenteriaeon consecutive days. Increasing dietary levels of inulin linearly (P = 0·001) reduced the risk of pigs developing SD; however, eight out of fifteen pigs fed the diet with 80 g/kg inulin still developed the disease. The pH values in the caecum (P = 0·072) tended to decrease, and in the upper colon, the pH values did decrease (P = 0·047) linearly with increasing inulin levels in the diets, most probably due to a linear increase in the concentration of total volatile fatty acids in the caecum (P = 0·018), upper colon (P = 0·001) and lower colon (P = 0·013). In addition, there was a linear reduction in the proportion of the branched-chain fatty acids isobutyric acid and isovaleric acid in the caecum (P = 0·015 and 0·026) and upper colon (P = 0·011 and 0·013) with increasing levels of dietary inulin. In conclusion, the present study showed that a diet supplemented with a high level of inulin (80 g/kg) but not lower levels reduced the risk of pigs developing SD, possibly acting through a modification of the microbial fermentation patterns in the large intestine.
Effect of the fat composition of a single high-fat meal on inflammatory markers in healthy young women
Authors: Myhrstad Mari C. W. , Narverud Ingunn , Telle-Hansen Vibeke H. , Karhu Toni , Bødtker Lund Daniel , Herzig Karl-Heinz , Makinen Markus , Halvorsen Bente , Retterstøl Kjetil , Kirkhus Bente , Granlund Linda , Holven Kirsten B. , Ulven Stine M.
Published: June 2011

The aim of the present study was to examine the effect of a single high-fat meal with different fat quality on circulating inflammatory markers and gene expression in peripheral blood mononuclear cells (PBMC) to elucidate the role of fat quality on postprandial inflammation. A postprandial study with fourteen healthy females consuming three test meals with different fat quality was performed. Test days were separated by 2 weeks. Fasting and postprandial blood samples at 3 and 6 h after intake were analysed. The test meal consisted of three cakes enriched with coconut fat (43 % energy as saturated fat and 1 % energy as α-linolenic acid (ALA)), linseed oil (14 % energy as ALA and 30 % energy as saturated fat) and cod liver oil (5 % energy as EPA and DHA and 5 % energy as ALA in addition to 31 % energy as saturated fat). In addition, ex vivo PBMC experiments were performed in eight healthy subjects investigating the effects of EPA and ALA on release and gene expression of inflammatory markers. The IL-8 mRNA level was significantly increased after intake of the cod liver oil cake at 6 h compared with fasting level, which was significantly different from the effect observed after the intake of linseed cake. In contrast, no effect was seen on circulating level of IL-8. In addition, ALA and EPA were shown to elicit different effects on the release and mRNA expression levels of inflammatory markers in PBMC cultured ex vivo, with EPA having the most prominent pro-inflammatory potential.
Tracheal resection with end-to-end anastomosis for post-intubation cervical tracheal stenosis: study of 14 cases
Authors: Nandakumar R , Jagdish C , Prathibha C B , Shilpa C , Sreenivas V , Balasubramanya A M , Nayar R C
Published: June 2011

Background and objectives:

The incidence of acquired laryngeal stenosis is increasing. This retrospective study aimed to assess the long term results of circumferential resection with end-to-end tracheal anastomosis for isolated post-intubation stenosis of the cervical trachea, and to review the relevant literature.

Methods:

Twelve male and two female patients (aged 16–30 years, mean age 24 years) treated between February 2003 and December 2008 were included. Hospital and office records were reviewed and relevant surgical details recorded.

Results:

Indications for tracheal resection anastomosis were post-intubation stenosis (78.57 per cent) and trauma (21.42 per cent). One to five tracheal rings were resected (i.e. 1–2.5 cm of cervical trachea). Tracheal anastomosis was considered successful if the patient remained asymptomatic for 24 months of close follow up (involving regular flexible bronchoscopy and neck X-ray). The anastomotic success rate was 92.85 per cent.

Conclusion:

Tracheal resection and end-to-end anastomosis is relatively safe and reliable for definitive treatment of benign tracheal stenosis in appropriate patients. Local application of mitomycin C prevents granulation and aids long term airway patency.
Information Fusion for Localization Within Vehicular Networks
Authors: Efatmaneshnik Mahmoud , Kealy Allison , Balaei Asghar Tabatabei , Dempster Andrew G.
Published: June 2011

Cooperative positioning (CP) is a localization technique originally developed for use across wireless sensor networks. With the emergence of Dedicated Short Range Communications (DSRC) infrastructure for use in Intelligent Transportation Systems (ITS), CP techniques can now be adapted for use in location determination across vehicular networks. In vehicular networks, the technique of CP fuses GPS positions with additional sensed information such as inter-vehicle distances between the moving vehicles to determine their location within a neighbourhood. This paper presents the results obtained from a research study undertaken to demonstrate the capabilities of DSRC for meeting the positioning accuracies of road safety applications. The results show that a CP algorithm that fully integrates both measured/sensed data as well as navigation information such as map data can meet the positioning requirements of safety related applications of DSRC (<0·5 m). This paper presents the results of a Cramer Rao Lower Bound analysis which is used to benchmark the performance of the CP algorithm developed. The Kalman Filter (KF) models used in the CP algorithm are detailed and results obtained from integrating GPS positions, inter-vehicular ranges and information derived from in-vehicle maps are then discussed along with typical results as determined through a variety of network simulation studies.
Seasoned adaptive antibody immunity for highly pathogenic pandemic influenza in humans
Authors: Lynch Garry W , Selleck Paul , Church W Bret , Sullivan John S
Published: June 2011

Fundamentally new approaches are required for the development of vaccines to pre‐empt and protect against emerging and pandemic influenzas. Current strategies involve post‐emergent homotypic vaccines that are modelled upon select circulating ‘seasonal’ influenzas, but cannot induce cross‐strain protection against newly evolved or zoonotically introduced highly pathogenic influenza (HPI). Avian H5N1 and the less‐lethal 2009 H1N1 and their reassortants loom as candidates to seed a future HPI pandemic. Therefore, more universal ‘seasoned’ vaccine approaches are urgently needed for heterotypic protection ahead of time. Pivotal to this is the need to understand mechanisms that can deliver broad strain protection. Heterotypic and heterosubtypic humoral immunities have largely been overlooked for influenza cross‐protection, with most ‘seasoned’ vaccine efforts for humans focussed on heterotypic cellular immunity. However, 5 years ago we began to identify direct and indirect indicators of humoral‐herd immunity to protein sites preserved among H1N1, H3N2 and H5N1 influenzas. Since then the evidence for cross‐protective antibodies in humans has been accumulating. Now proposed is a rationale to stimulate and enhance pre‐existing heterotypic humoral responses that, together with cell‐mediated initiatives, will deliver pre‐emptive and universal human protection against emerging epidemic and pandemic influenzas.
Wellcome Trust Policy on Data Management and Sharing
Authors: Carr David
Published: June 2011

The Wellcome Trust's policy statement on data management and sharing, which was originally published in January 2007 and revised in August 2010.
The phase behavior of two-dimensional symmetrical mixtures in a weak external field of square symmetry
Authors: Materniak S. , Patrykiejew A. , Sokołowski S.
Published: June 2011

Using Monte Carlo simulation methods in the grand canonical and semigrand canonical ensembles, we study the phase behavior of two-dimensional symmetrical binary mixtures of Lennard-Jones particles subjected to a weakly corrugated external field of a square symmetry. It is shown that the both vapor-liquid condensation and demixing transition in the liquid phase are not appreciably affected by a weakly corrugated external field. On the other hand, even a weakly corrugated external field considerably influences the structure of solid phases and the liquid-solid transition. In particular, the solid phases are found to exhibit uniaxially ordered distorted hexagonal structure. The triple point temperature increases with the corrugation of the external field, while the triple point density becomes lower when the surface corrugation increases. The changes in the location of the triple point are shown to lead to the changes of the phase diagram topology. It is also demonstrated that the solid phase undergoes a demixing transition, which is also very slightly affected by the weakly corrugated external potential. The demixing transition in the solid phase is shown to belong to the universality class of the Ising model.
Spatially advancing coherent structures in curved channel turbulent flow
Authors: Matsubara Koji , Sakurai Atsushi , Yamazaki Kenya , Takeda Makoto
Published: June 2011

Direct numerical simulation was performed for the spatially advancing turbulent flow in a two-dimensional curved channel. The fully developed turbulence was introduced into the curved channel through a straight part, and observation was made for how the near-wall turbulence advanced along curved walls. The frictional Reynolds number, Reτ0, was fixed at 150, whereas the radius ratio of the curved channel, α, was changed at three steps; 0.8, 0.92, and 0.975. Five computational tests were performed, which include simulations with changing the spanwise length of the channel or the grid arrangement. The maximum number of grid points was 43,610,112 (=936 × 91 × 512) used in the case of α = 0.92. Numerical results for the curved flow were nearly free from the grid arrangement or the spanwise length of the channel, and changes of the mean velocity qualitatively agreed with the experiment by Kobayashi et al. [Trans. Jpn. Soc. Mech. Eng., Ser. B 57, 4064 (1991)], which both supported credibility of the simulation. The spanwise pre-multiplied power spectrum and the spanwise two-point correlation captured the peaks corresponding to the micro-scale structures near the straight wall, which continuously grew along the concave wall and advanced to exhibit the wave length of organized flows. Therefore, the micro-scale structures such as quasi-stream vortices and the ejection near the outer wall of the straight channel were suggested to trigger the onset of initial seeds of the organized structure, which grew into the large scale vortices expanding almost over the channel width.
The surface boundary conditions in GaN/AlGaN/GaN transistor heterostructures
Authors: Gladysiewicz M. , Kudrawiec R. , Misiewicz J. , Cywinski G. , Siekacz M. , Wolny P. , Skierbiszewski C.
Published: June 2011

The distribution of electric field in GaN(cap)/AlGaN/GaN(buffer) transistor heterostructures with various AlGaN layer thicknesses (10, 20, and 30 nm) has been studied by contactless electroreflectance and compared with theoretical calculations performed for various positions of the Fermi-level on GaN surface. For the three samples the best agreement between experimental data and theoretical calculations has been found at the same position of the Fermi-level on GaN surface (i.e., 0.55±0.05 eV below the conduction band). It means that the Fermi-level is pinned on GaN surface and this pinning can be treated as the boundary condition for the distribution of polarization-related fields in this heterostructure.
Hard sphere fluids at a soft repulsive wall: A comparative study using Monte Carlo and density functional methods
Authors: Deb Debabrata , Winkler Alexander , Yamani Mohammad Hossein , Oettel Martin , Virnau Peter , Binder Kurt
Published: June 2011

Hard-sphere fluids confined between parallel plates at a distance D apart are studied for a wide range of packing fractions including also the onset of crystallization, applying Monte Carlo simulation techniques and density functional theory. The walls repel the hard spheres (of diameter σ) with a Weeks-Chandler-Andersen (WCA) potential VWCA(z) = 4ε[(σw/z)12 − (σw/z)6 + 1/4], with range σw = σ/2. We vary the strength ε over a wide range and the case of simple hard walls is also treated for comparison. By the variation of ε one can change both the surface excess packing fraction and the wall-fluid (γwf) and wall-crystal (γwc) surface free energies. Several different methods to extract γwf and γwc from Monte Carlo (MC) simulations are implemented, and their accuracy and efficiency is comparatively discussed. The density functional theory (DFT) using fundamental measure functionals is found to be quantitatively accurate over a wide range of packing fractions; small deviations between DFT and MC near the fluid to crystal transition need to be studied further. Our results on density profiles near soft walls could be useful to interpret corresponding experiments with suitable colloidal dispersions.
Extended multi-configuration quasi-degenerate perturbation theory: The new approach to multi-state multi-reference perturbation theory
Authors: Granovsky Alexander A.
Published: June 2011

The distinctive desirable features, both mathematically and physically meaningful, for all partially contracted multi-state multi-reference perturbation theories (MS-MR-PT) are explicitly formulated. The original approach to MS-MR-PT theory, called extended multi-configuration quasi-degenerate perturbation theory (XMCQDPT), having most, if not all, of the desirable properties is introduced. The new method is applied at the second order of perturbation theory (XMCQDPT2) to the 11A′ – 21A′ conical intersection in allene molecule, the avoided crossing in LiF molecule, and the 11A1 to 21A1 electronic transition in cis-1,3-butadiene. The new theory has several advantages compared to those of well-established approaches, such as second order multi-configuration quasi-degenerate perturbation theory and multi-state-second order complete active space perturbation theory. The analysis of the prevalent approaches to the MS-MR-PT theory performed within the framework of the XMCQDPT theory unveils the origin of their common inherent problems. We describe the efficient implementation strategy that makes XMCQDPT2 an especially useful general-purpose tool in the high-level modeling of small to large molecular systems.
Uneven Public Transportation Development in Neoliberalizing Chicago, USA
Authors: Farmer Stephanie
Published: June 2011

This paper examines how neoliberal urbanization has transformed the role of public transportation into an entrepreneurial tool that creates place-based advantages for capital in global cities. Using Chicago, USA as a case study, I examine new transit-construction projects focused on Chicago's downtown Central Area—the Express Airport Service and Circle Line—to demonstrate how public transit infrastructure is increasingly deployed as a means to attract global capital as well as enhance affluent residents' and tourists' rights to the city. I contrast these projects to the lack of new public transit investment for areas outside of Chicago's downtown global city showcase zone. Declining service levels and unreliable transit infrastructure due to the neoliberal retrenchment in the public sector are also constricting working people's right to the city. Taken together, these trends express the nature of uneven public transit development emerging in the neoliberal city of Chicago.
Transition towards Sustainable Cities: Opportunities, Constraints, and Strategies in Planning. A Neighbourhood Ecodesign Case Study in Barcelona
Authors: Farreny Ramon , Oliver-Solà Jordi , Montlleó Marc , Escribà Enric , Gabarrell Xavier , Rieradevall Joan
Published: June 2011

Despite covering only 2.7% of the world's total surface area, the world's cities are responsible for 75% of the world's energy consumption and 80% of greenhouse-gas emissions. For this reason, the redesign of cities is essential in the transition towards sustainability. However, planning and designing sustainable neighbourhoods is not a simple task, given that there is no agreement on what the sustainable settlement should be, nor on how this should be achieved. Furthermore, planners have to strive to achieve a balance between financial, environmental, and social goals, and must deal with multiple actors and stakeholders and with site-specific characteristics. The aim of this work is to describe the key determining factors—both opportunities and constraints—found in the process of designing and planning a neighbourhood, based on a case study in the city of Barcelona. In this practical experiment, led by the authors, the ecodesign methodology was applied on an urban scale in the neighbourhood of Vallbona, Barcelona, which occupies an area of 32.6 ha and will host 2120 dwellings. From this neighbourhood ecodesign exercise, it was found that territorial (urban form, urban fabrics, and density; availability of local resources), financial, legal, and political (local government's wishes and leadership) determinants are the most important. It is concluded that there is no single path to achieve urban sustainability, since the design of neighbourhoods in different locations will lead to different results.
On–off system for PI3-kinase–Akt signaling through
S
-nitrosylation of phosphatase with sequence homology to tensin (PTEN)
Authors: Numajiri Naoki , Takasawa Kumi , Nishiya Tadashi , Tanaka Hirotaka , Ohno Kazuki , Hayakawa Wataru , Asada Mariko , Matsuda Hiromi , Azumi Kaoru , Kamata Hideaki , Nakamura Tomohiro , Hara Hideaki , Minami Masabumi , Lipton Stuart A. , Uehara Takashi
Published: June 2011

Nitric oxide (NO) physiologically regulates numerous cellular responses through
S
-nitrosylation of protein cysteine residues. We performed antibody-array screening in conjunction with biotin-switch assays to look for
S
-nitrosylated proteins. Using this combination of techniques, we found that phosphatase with sequence homology to tensin (PTEN) is selectively
S
-nitrosylated by low concentrations of NO at a specific cysteine residue (Cys-83).
S
-nitrosylation of PTEN (forming SNO-PTEN) inhibits enzymatic activity and consequently stimulates the downstream Akt cascade, indicating that Cys-83 is a critical site for redox regulation of PTEN function. In ischemic mouse brain, we observed SNO-PTEN in the core and penumbra regions but found SNO-Akt, which is known to inhibit Akt activity, only in the ischemic core. These findings suggest that low concentrations of NO, as found in the penumbra, preferentially
S
-nitrosylate PTEN, whereas higher concentrations of NO, known to exist in the ischemic core, also
S
-nitrosylate Akt. In the penumbra, inhibition of PTEN (but not Akt) activity by
S
-nitrosylation would be expected to contribute to cell survival by means of enhanced Akt signaling. In contrast, in the ischemic core, SNO-Akt formation would inhibit this neuroprotective pathway. In vitro model systems support this notion. Thus, we identify unique sites of PTEN and Akt regulation by means of
S
-nitrosylation, resulting in an “on–off” pattern of control of Akt signaling.
Crystal structure of the MID-PIWI lobe of a eukaryotic Argonaute protein
Authors: Boland Andreas , Huntzinger Eric , Schmidt Steffen , Izaurralde Elisa , Weichenrieder Oliver
Published: June 2011

Argonaute proteins (AGOs) are essential effectors in RNA-mediated gene silencing pathways. They are characterized by a bilobal architecture, in which one lobe contains the N-terminal and PAZ domains and the other contains the MID and PIWI domains. Here, we present the first crystal structure of the MID-PIWI lobe from a eukaryotic AGO, the
Neurospora crassa
QDE-2 protein. Compared to prokaryotic AGOs, the domain orientation is conserved, indicating a conserved mode of nucleic acid binding. The PIWI domain shows an adaptable surface loop next to a eukaryote-specific α-helical insertion, which are both likely to contact the PAZ domain in a conformation-dependent manner to sense the functional state of the protein. The MID-PIWI interface is hydrophilic and buries residues that were previously thought to participate directly in the allosteric regulation of guide RNA binding. The interface includes the binding pocket for the guide RNA 5′ end, and residues from both domains contribute to binding. Accordingly, micro-RNA (miRNA) binding is particularly sensitive to alteration in the MID-PIWI interface in
Drosophila melanogaster
AGO1 in vivo. The structure of the QDE-2 MID-PIWI lobe provides molecular and mechanistic insight into eukaryotic AGOs and has significant implications for understanding the role of these proteins in silencing.
Direct conversion of human fibroblasts to dopaminergic neurons
Authors: Pfisterer Ulrich , Kirkeby Agnete , Torper Olof , Wood James , Nelander Jenny , Dufour Audrey , Björklund Anders , Lindvall Olle , Jakobsson Johan , Parmar Malin
Published: June 2011

Recent reports demonstrate that somatic mouse cells can be directly converted to other mature cell types by using combined expression of defined factors. Here we show that the same strategy can be applied to human embryonic and postnatal fibroblasts. By overexpression of the transcription factors Ascl1, Brn2, and Myt1l, human fibroblasts were efficiently converted to functional neurons. We also demonstrate that the converted neurons can be directed toward distinct functional neurotransmitter phenotypes when the appropriate transcriptional cues are provided together with the three conversion factors. By combining expression of the three conversion factors with expression of two genes involved in dopamine neuron generation,
Lmx1a
and
FoxA2
, we could direct the phenotype of the converted cells toward dopaminergic neurons. Such subtype-specific induced neurons derived from human somatic cells could be valuable for disease modeling and cell replacement therapy.
Human cystic fibrosis airway epithelia have reduced Cl
−
conductance but not increased Na
+
conductance
Authors: Itani Omar A. , Chen Jeng-Haur , Karp Philip H. , Ernst Sarah , Keshavjee Shaf , Parekh Kalpaj , Klesney-Tait Julia , Zabner Joseph , Welsh Michael J.
Published: June 2011

Loss of cystic fibrosis transmembrane conductance regulator (CFTR) anion channel function causes cystic fibrosis (CF) lung disease. CFTR is expressed in airway epithelia, but how CF alters electrolyte transport across airway epithelia has remained uncertain. Recent studies of a porcine model showed that in vivo, excised, and cultured

CFTR
−/−

and

CFTR
ΔF508/ΔF508

airway epithelia lacked anion conductance, and they did not hyperabsorb Na
+
. Therefore, we asked whether Cl
−
and Na
+
conductances were altered in human CF airway epithelia. We studied differentiated primary cultures of tracheal/bronchial epithelia and found that transepithelial conductance (Gt) under basal conditions and the cAMP-stimulated increase in Gt were markedly attenuated in CF epithelia compared with non-CF epithelia. These data reflect loss of the CFTR anion conductance. In CF and non-CF epithelia, the Na
+
channel inhibitor amiloride produced similar reductions in Gt and Na
+
absorption, indicating that Na
+
conductance in CF epithelia did not exceed that in non-CF epithelia. Consistent with previous reports, adding amiloride caused greater reductions in transepithelial voltage and short-circuit current in CF epithelia than in non-CF epithelia; these changes are attributed to loss of a Cl
−
conductance. These results indicate that Na
+
conductance was not increased in these cultured CF tracheal/bronchial epithelia and point to loss of anion transport as key to airway epithelial dysfunction in CF.
Facial Attractiveness Biases the Perception of Eye Contact
Authors: Kloth Nadine , Altmann Carolin S. , Schweinberger Stefan R.
Published: June 2011

Attractive faces are appealing: We like to look at them, and we like to be looked at by them. We presented attractive and unattractive smiling and neutral faces containing identical eye regions with different gaze directions. Participants judged whether or not a face looked directly at them. Overall, attractive faces increased participants' tendency to perceive eye contact, consistent with a self-referential positivity bias. However, attractiveness effects were modulated by facial expression and gender: For female faces, observers more likely perceived eye contact in attractive than unattractive faces, independent of expression. For male faces, attractiveness effects were limited to neutral expressions and were absent in smiling faces. A signal detection analysis elucidated a systematic pattern in which (a) smiling faces, but not highly attractive faces, reduced sensitivity in gaze perception overall, and (b) attractiveness had a more consistent impact on bias than sensitivity measures. We conclude that combined influences of attractiveness, expression, and gender determine the formation of an overall impression when deciding which individual's interest in oneself may be beneficial and should be reciprocated.
Developmental Changes in the Control of Saccadic Eye Movements in Response to Directional Eye Gaze and Arrows
Authors: Kuhn Gustav , Tewson Lauren , Morpurgo Lea , Freebody Susannah F. , Musil Anna S. , Leekam Susan R.
Published: June 2011

We investigated developmental differences in oculomotor control between 10-year-old children and adults using a central interference task. In this task, the colour of a fixation point instructed participants to saccade either to the left or to the right. These saccade directions were either congruent or incongruent with two types of distractor cue: either the direction of eye gaze of a centrally presented schematic face, or the direction of arrows. Children had greater difficulties inhibiting the distractor cues than did adults, which revealed itself in longer saccade latencies for saccades that were incongruent with the distractor cues as well as more errors on these incongruent trials than on congruent trials. Counter to our prediction, in terms of saccade latencies, both children and adults had greater difficulties inhibiting the arrow than the eye gaze distractors.
The Need to Explain
Authors: Khemlani Sangeet S. , Johnson-Laird Philip N.
Published: June 2011

How do reasoners deal with inconsistencies? James (1907) believed that the rational solution is to revise your beliefs and to do so in a minimal way. We propose an alternative: You explain the origins of an inconsistency, which has the side effect of a revision to your beliefs. This hypothesis predicts that individuals should spontaneously create explanations of inconsistencies rather than refute one of the assertions and that they should rate explanations as more probable than refutations. A pilot study showed that participants spontaneously explain inconsistencies when they are asked what follows from inconsistent premises. In three subsequent experiments, participants were asked to compare explanations of inconsistencies against minimal refutations of the inconsistent premises. In Experiment 1, participants chose which conclusion was most probable; in Experiment 2 they rank ordered the conclusions based on their probability; and in Experiment 3 they estimated the mean probability of the conclusions' occurrence. In all three studies, participants rated explanations as more probable than refutations. The results imply that individuals create explanations to resolve an inconsistency and that these explanations lead to changes in belief. Changes in belief are therefore of secondary importance to the primary goal of explanation.
Apuleius
Authors: Harrison Stephen
Published: June 2011

Apuleius (no other names certain, c. 125–after 170 ce) is one of the key Latin writers of the 2nd century ce, a period that marks the transition from the end of traditional classical culture (Tacitus and Juvenal were probably still alive when Apuleius was born) to the new world of the high empire (Tertullian was certainly born before his death). He can be seen as representing in the Latin West some key aspects of the so-called Greek Second Sophistic, such as a focus on rhetorical performance and an interest in archaic language. He practiced as rhetorician and teacher in Carthage, and his writings were clearly well known in Late Antiquity in Roman North Africa (he is often mentioned by Augustine) and in Gaul (he is cited by Sidonius Apollinaris). He is best known for his novel Metamorphoses or The Golden Ass, and for its remarkable style: it is the apex of Asianism in Latin, full of poetic and archaic words and apparent coinages, rhythmical and rhyming cola, and colored with colloquialism and Graecisms. His Apologia (self-defense from 158 to 159 ce) is an immensely learned speech that combines Ciceronian forensic fireworks with sophistic epideixis, while the Florida, twenty-odd excerpts from Apuleius’s showy declamations delivered at Carthage in the 160s, show considerable rhetorical and stylistic talent, and the De deo Socratis (probably from the same period) is a declamation on the personal deity of Socrates as seen in Plato. Three extant works ascribed to Apuleius are of debated authenticity: De dogmate Platonis or De Platone, two books of mediocre exposition of the philosophy of Plato; De Interpretatione, a treatise on formal logic; and De mundo, a translation of the pseudo-Aristotelian treatise. Lost Apuleian works known from later citations include further speeches, poems, another novel, and a wide range of scientific and other didactic works. Little known in the medieval period, Apuleius was enthusiastically rediscovered in the Renaissance, and much read and studied, forming the center of debates about Latin prose style (Apuleius versus Cicero); his novel influenced important writers such as Shakespeare and Sidney, and the story of Cupid and Psyche from the Metamorphoses has provided consistent inspiration for further works of art and literature over the last five centuries. Little favored by classicists until the second half of the 20th century, he is now a much-researched author.
Sparta
Authors: Thommen Lukas
Published: June 2011

Alongside Athens, Sparta is considered as the second mighty polis in the Greek world and has always attracted admiration as well as criticism, so that its image has undergone many transformations. Sparta was time and again represented as the counterpart of Athens and assigned the role of a backward oligarchy and legally, rigidly regulated military state. In Antiquity (cf. Xenophon and Plato) the political stability and military efficiency of Sparta were declared an ideal and traced back to the system of public education (agoge). In the course of the 4th century bce, Aristotle finally proclaimed Sparta a pattern for a “mixed constitution,” which contains monarchic as well as aristocratic and democratic elements (kings, gerontes, and ephors, or the leaders of the popular assembly). Following this outline, it later became also a model for the Romans (Polybius, Book 6). On the other hand, the “equality” of the Spartans, who termed themselves homoioi (“equals”), has always been fascinating. Connected with this equality was the communal life of Spartan men in the form of a permanent military-style camp. The idea of severe regulation of all facets of life and its orientation toward the state resulted in the early 20th century in the denotation of the Spartan community as a “kosmos,” so that Sparta also became a modern myth. Yet the Spartan “mirage” has been continuously deconstructed since the publication of Ollier 1933–1943 (see Spartan Tradition and Research History, Post-1900). Recently, there has been ongoing debate between researchers who think Sparta was more like other Greek states than sources note, and those who think it was unique.
Buddhist Art and Architecture in Tibet
Authors: Gray David
Published: June 2011

Fifty years ago, Tibetan art and architecture were fields in an early stage of development in the West. Early Western knowledge of Tibetan art and architecture was largely due to the pioneering work of early 20th-century scholars such as Giuseppe Tucci, Joseph Hackin, and Alice Getty. These fields have developed significantly over the past few decades, for multiple reasons. These reasons include general growth in interest in Tibetan culture and religion following the Chinese occupation of Tibet, and in the Tibetan diaspora, from the 1950s onward. The Cultural Revolution in the 1960s and 1970s in China led to the destruction of a tremendous amount of Tibetan art and architecture, and to the displacement within China of many works of Tibetan art that were not destroyed. However, the opening of China to the outside world in the post-Mao era led to the growing availability of Tibetan art on international art markets and gave foreign scholars access to surviving architectural monuments. This has led to a rapid growth in the understanding of Tibetan art history and stylistics. This work has been undertaken by a wide range of scholars, from North America and Europe, as well as Japan and India. More recently, there has also been considerable growth in scholarship within China by Tibetan and Han Chinese scholars.
Classical Indian Buddhist Philosophy
Authors: Powers John
Published: June 2011

Classical Indian Buddhist philosophy encompasses a vast range of thinkers, schools, and issues. One important tradition is abhidharma (higher doctrine), a scholastic philosophy that examined key elements of Buddhist teaching and developed often elaborate and highly detailed analyses of the psycho-physical elements of existence. Early Buddhism is commonly divided into eighteen philosophical schools—including such influential traditions as Sarvāstivāda, Vaibhāṣika, Sautrāntika, Sthaviravāda, Mahāsāṃghika, and so forth—though more are actually mentioned in Indic sources. Each of these developed its own distinctive philosophical system and engaged in debate with both Buddhist and non-Buddhist rivals. With the rise of Mahayana, new philosophical systems—including the Middle Way school (Mādhyamika), the Yogic Practice school (Yogācāra), and the Epistemological school (Pramāṇa)—developed. Tantric Buddhism added a new stream of philosophical thought that developed the conceptual implications of tantric scriptural texts.
Classes of Beings
Authors: Feller Danielle , Policardi Chiara
Published: June 2011

Besides gods, men, and beasts, Hinduism, including its earlier phase Vedism, contains a whole array of semidivine beings. They appear most importantly in Vedic, epic, purāṇic, and kāvya literature. There is no obvious hierarchy among the different groups, whose natures range from benevolent to frankly evil (with considerable fluctuation over time). Some classes are more prominent than others, but each has its own mythological history: in purāṇic genealogies their origin is frequently traced back to certain demiurges. In Hinduism these beings, though powerful, are usually not immortal—not any more than most of the gods themselves—and are hence subject to rebirth according to the nature of their deeds. They are supposed to live in different realms, on the earth but also in underground worlds or in heavenly abodes in the vicinity of the gods. However, they frequently flock together to witness important events and are then listed in copulative compounds, such as “heavenly musicians, nymphs, sages, ghouls, demons, serpents, genies.” These lists display considerable variation, but the more prominent among them, which we shall examine here, are the Nāgas and Garuḍas; Apsarases and Gandharvas; Yakṣas; various types of demons, especially Asuras and Rākṣasas; Ṛṣis; Pitṛs, Pretas, and Bhūtas; and finally, Gaṇas and Yoginīs.
Sanctions
Authors: Ang Adrian
Published: June 2011

The study of sanctions is topical but also contentious and inconclusive in international relations. On the one hand, scholars are deeply divided on the utility of sanctions as foreign-policy instruments. There is an ongoing debate about the “success” or “effectiveness” of sanctions that has yielded a conventional wisdom that they are failed policy instruments. On the other hand, even as the effectiveness of sanctions remains mired in academic debate, its popularity as a policy instrument among policymakers has never been higher. Even among scholars who argue that sanctions can work, there is disagreement about the strategies for achieving success as well as when and why they succeed. The goals of this bibliography are to expose the reader to the debates surrounding the success or failure of sanctions; to explore the conditions under which sanctions might achieve success and the multiple reasons why states impose sanctions beyond mere compliance; to understand why policymakers continue to impose sanctions even if academics denigrate their failure; to explore the costs and consequences of sanctions; and to explore some of the methodological issues related to the study of economic sanctions.
War
Authors: Nolan Cathal
Published: June 2011

Modern war is often defined as armed conflict within, between, or among states, although other political communities partake of war: ethnic and religious groups, ideological movements, terrorist organizations, large drug gangs, and other “non-state actors.” The narrowest meaning used by historians is war as the art and science and record of military operations. More general discourse sub-classifies war according to an ascending scale of participation—rebellion, insurrection, insurgency, guerrilla war, civil war, and regional war—culminating in three synonyms for armed conflict at the largest scale: systemic war, global war, and world war. War is also categorized by the types of weapons used to conduct it, as in the terms “conventional war” and “unconventional war.” A controversial distinction is made between limited war and total war, in which wars are typed by scope, the declared or discerned objectives of participants, and the degree to which militaries target civilians, enemy morale, or economic infrastructure. Social science literature defines a minimal threshold of mass political violence as war, as opposed to riot or other communal use of force, if deaths reach one thousand. That is an arbitrary definition, not universally accepted or normally employed by historians.