@article{343, abstract = {The bottom-up assembly of nanocrystals provides access to a three-dimensional composition control at the nanoscale not attainable by any other technology. In particular, colloidal nanoheterostructures, with intrinsic multiphase organization, are especially appealing building blocks for the bottom-up production of nanocomposites. In the present work, we use PbTe-PbS as the model material system and thermoelectricity as the paradigmatic application to investigate the potential of the bottom-up assembly of core-shell nanoparticles to produce functional nanocomposites. With this goal in mind, a rapid, high-yield and scalable colloidal synthetic route to prepare grams of PbTe@PbS core-shell nanoparticles with unprecedented narrow size distributions and exceptional composition control is detailed. PbTe@PbS nanoparticles were used as building blocks for the bottom-up production of PbTe-PbS nanocomposites with tuned composition. In such PbTe-PbS nanocomposites, synergistic nanocrystal doping effects result in up to 10-fold higher electrical conductivities than in pure PbTe and PbS nanomaterials. At the same time, the acoustic impedance mismatch between PbTe and PbS phases and a partial phase alloying provide PbTe-PbS nanocomposites with strongly reduced thermal conductivities. As a result, record thermoelectric figures of merit (ZT) of ∼1.1 were obtained from undoped PbTe and PbS phases at 710 K. These high ZT values prove the potential of the proposed processes to produce efficient functional nanomaterials with programmable properties. © 2013 American Chemical Society.}, author = {Ibáñez, Maria and Zamani, Reza and Gorsse, Stéphane and Fan, Jiandong and Ortega, Silvia and Cadavid, Doris and Morante, Joan and Arbiol, Jordi and Cabot, Andreu}, journal = {ACS Nano}, number = {3}, pages = {2573 -- 2586}, publisher = {American Chemical Society}, title = {{Core shell nanoparticles as building blocks for the bottom-up production of functional nanocomposites: PbTe PbS thermoelectric properties}}, doi = {10.1021/nn305971v}, volume = {7}, year = {2013}, } @article{344, abstract = {Copper-based selenides are attracting increasing interest due to their outstanding optoelectronic and thermoelectric properties. Herein a novel colloidal synthetic route to prepare Cu2SnSe3 nanocrystals with controlled size, shape and composition is presented. The high yield of the developed procedure allowed its up-scaling to the production of grams of colloidal Cu2SnSe3 nanocrystals. These nanocrystals were used as building blocks for the production of Cu2SnSe3 bulk nanostructured materials by spark plasma sintering. The thermoelectric properties of the prepared nanocrystalline Cu2SnSe3 pellets were characterized in the temperature range from 300 to 720 K. The obtained results show the bottom-up production of nanocrystalline materials from solution-processed nanocrystals to be a potentially advantageous alternative to conventional methods of production of efficient thermoelectric materials.}, author = {Ibáñez, Maria and Cadavid, Doris and Anselmi Tamburini, Umberto and Zamani, Reza and Gorsse, Stéphane and Li, Wenhua and López, Antonio and Morante, Joan and Arbiol, Jordi and Cabot, Andreu}, journal = {Journal of Materials Chemistry A}, number = {4}, pages = {1421 -- 1426}, publisher = {Royal Society of Chemistry}, title = {{Colloidal synthesis and thermoelectric properties of Cu 2SnSe3 nanocrystals}}, doi = {10.1039/C2TA00419D}, volume = {1}, year = {2013}, } @article{351, abstract = {A multistrategy approach to overcome the main challenges of nanoparticle-based solution-processed Cu2ZnSnSe4 thin film solar cells is presented. We developed an efficient ligand exchange strategy, using an antimony salt, to displace organic ligands from the surface of Cu 2ZnSnS4 nanoparticles. An automated pulsed spray-deposition system was used to deposit the nanoparticles into homogeneous and crack-free films with controlled thickness. After annealing the film in a Se-rich atmosphere, carbon-free and crystalline Cu2ZnSnSe4 absorber layers were obtained. Not only was crystallization promoted by the complete removal of organics, but also Sb itself played a critical role. The Sb-assisted crystal growth is associated with the formation of a Sb-based compound at the grain boundaries, which locally reduces the melting point, thus promoting the film diffusion-limited crystallization. }, author = {Carrete, Alex and Shavel, Alexey and Fontané, Xavier and Montserrat, Joana and Fan, Jiandong and Ibáñez, Maria and Saucedo, Edgardo and Pérez Rodríguez, Alejandro and Cabot, Andreu}, journal = {Journal of the American Chemical Society}, number = {43}, pages = {15982 -- 15985}, publisher = {American Chemical Society}, title = {{Antimony-based ligand exchange to promote crystallization in spray-deposited Cu2ZnSnSe4 solar cells}}, doi = {10.1021/ja4068639}, volume = {135}, year = {2013}, } @article{352, abstract = {The presence of organic ligands on the surface of colloidal nanoparticles strongly limits their performance in technological applications where charge carrier transfer/transport plays an important role. We use metal salts, matched with the nanoparticle composition, to eliminate the surface organic ligands without introducing extrinsic impurities in the final nanomaterial. The potential of the simple, general and scalable processes presented here is demonstrated by characterizing the thermoelectric properties of nanostructured Ag2Te produced by the bottom up assembly of Ag2Te nanocrystals. A 6-fold increase of the thermoelectric figure of merit of Ag2Te was obtained when organic ligands were displaced by AgNO3. The same procedure can enhance the performance of nanocrystals and nanocrystal-based devices in a broad range of applications, from photovoltaics and thermoelectrics to catalysis.}, author = {Cadavid, Doris and Ibáñez, Maria and Shavel, Alexey and Durá, Oscar and López De La Torre, Marco and Cabot, Andreu}, journal = {Journal of Materials Chemistry A}, number = {15}, pages = {4864 -- 4870}, publisher = {Royal Society of Chemistry}, title = {{Organic ligand displacement by metal salts to enhance nanoparticle functionality: Thermoelectric properties of Ag inf 2 inf Te}}, doi = {10.1039/C3TA01455J}, volume = {1}, year = {2013}, } @article{376, abstract = {The compositional versatility of I2–II–IV–VI4 tetrahedrally-coordinated compounds allows for accommodating their functional properties to numerous technological applications. Among them, Cu2ZnSnSe4 is an emerging photovoltaic material and Cu2CdSnSe4 displays excellent thermoelectric properties. The third compound of this family, Cu2HgSnSe4, remains relatively unexplored. Herein, a synthetic route to produce Cu2HgSnSe4 nanoparticles with narrow size distribution and controlled composition is presented. Cu2HgSnSe4 nanoparticles were subsequently used as building blocks to produce bulk nanocrystalline materials, whose thermoelectric properties were analyzed. A very preliminary adjustment of the material composition yielded Seebeck coefficients up to 160 μV K−1, electrical conductivities close to 104 S m−1 and thermal conductivities down to 0.5 W m−1 K−1.}, author = {Li, Wenhua and Ibáñez, Maria and Zamani, Reza and García Castelló, Nuria and Stéphane, Grosse and Cadavid, Doris and Prades, Joan and Arbiol, Jordi and Cabot, Andreu}, journal = {CrystEngComm}, pages = {8966 -- 8971}, publisher = {Royal Society of Chemistry}, title = {{Cu2HgSnSe4 nanoparticles: synthesis and thermoelectric properties}}, doi = {10.1039/C3CE41583J}, volume = {44}, year = {2013}, } @article{378, abstract = {Until recently, to prepare nanocrystals of a new material, scientists searched their shelves for the appropriate molecular precursors, surfactants, and solvents. They then optimized the reaction conditions for the atoms to self-assemble into monodisperse nanocrystals (1). This approach is being replaced by a simpler strategy, in which preformed nanocrystals serve as templates to produce nanoparticles with a different composition through chemical transformation. On page 964 of this issue, Oh et al. (2) report a powerful mechanism that allows the composition of oxide nanoparticles to be transformed in solution and at low temperatures.}, author = {Ibáñez, Maria and Cabot, Andreu}, journal = {Science}, number = {6135}, pages = {935 -- 936}, publisher = {American Association for the Advancement of Science}, title = {{All change for nanocrystals}}, doi = {10.1126/science.1239221}, volume = {340}, year = {2013}, } @article{450, abstract = {Understanding the relative importance of heterosis and outbreeding depression over multiple generations is a key question in evolutionary biology and is essential for identifying appropriate genetic sources for population and ecosystem restoration. Here we use 2455 experimental crosses between 12 population pairs of the rare perennial plant Rutidosis leptorrhynchoides (Asteraceae) to investigate the multi-generational (F1, F2, F3) fitness outcomes of inter-population hybridization. We detected no evidence of outbreeding depression, with inter-population hybrids and backcrosses showing either similar fitness or significant heterosis for fitness components across the three generations. Variation in heterosis among population pairs was best explained by characteristics of the foreign source or home population, and was greatest when the source population was large, with high genetic diversity and low inbreeding, and the home population was small and inbred. Our results indicate that the primary consideration for maximizing progeny fitness following population augmentation or restoration is the use of seed from large, genetically diverse populations.}, author = {Pickup, Melinda and Field, David and Rowell, David and Young, Andrew}, journal = {Proceedings of the Royal Society of London Series B Biological Sciences}, number = {1750}, publisher = {Royal Society, The}, title = {{Source population characteristics affect heterosis following genetic rescue of fragmented plant populations}}, doi = {10.1098/rspb.2012.2058}, volume = {280}, year = {2013}, } @inproceedings{11656, abstract = {Suppose your sole interest in recommending a product to me is to maximize the amount paid to you by the seller for a sequence of recommendations. How should you recommend optimally if I become more inclined to ignore you with each irrelevant recommendation you make? Finding an answer to this question is a key challenge in all forms of marketing that rely on and explore social ties; ranging from personal recommendations to viral marketing. We prove that even if the recommendee regains her initial trust on each successful recommendation, the expected revenue the recommender can make over an infinite period due to payments by the seller is bounded. This can only be overcome when the recommendee also incrementally regains trust during periods without any recommendation. Here, we see a connection to "banner blindness," suggesting that showing fewer ads can lead to a higher long-term revenue.}, author = {Dütting, Paul and Henzinger, Monika H and Weber, Ingmar}, booktitle = {Proceedings of the 21st ACM international conference on Information and knowledge management}, isbn = {9781450311564}, location = {Maui, HI, United States}, pages = {2268--2286}, publisher = {Association for Computing Machinery}, title = {{Maximizing revenue from strategic recommendations under decaying trust}}, doi = {10.1145/2396761.2398621}, year = {2012}, } @article{11751, abstract = {The Seebeck coefficients, electrical resistivities, total thermal conductivities, and magnetization are reported for temperatures between 5 and 350 K for n-type Bi0.88Sb0.12 nano-composite alloys made by Ho-doping at the 0, 1, and 3 % atomic levels. The alloys were prepared using a dc hot-pressing method, and are shown to be single phase for both Ho contents with grain sizes on the average of 900 nm. We find the parent compound has a maximum of ZT = 0.28 at 231 K, while doping 1 % Ho increases the maximum ZT to 0.31 at 221 K and the 3 % doped sample suppresses the maximum ZT = 0.24 at a temperature of 260 K.}, author = {Lukas, K. C. and Joshi, G. and Modic, Kimberly A and Ren, Z. F. and Opeil, C. P.}, issn = {1573-4803}, journal = {Journal of Materials Science}, number = {15}, pages = {5729--5734}, publisher = {Springer Nature}, title = {{Thermoelectric properties of Ho-doped Bi0.88Sb0.12}}, doi = {10.1007/s10853-012-6463-6}, volume = {47}, year = {2012}, } @inproceedings{11794, abstract = {We study individual rational, Pareto optimal, and incentive compatible mechanisms for auctions with heterogeneous items and budget limits. For multi-dimensional valuations we show that there can be no deterministic mechanism with these properties for divisible items. We use this to show that there can also be no randomized mechanism that achieves this for either divisible or indivisible items. For single-dimensional valuations we show that there can be no deterministic mechanism with these properties for indivisible items, but that there is a randomized mechanism that achieves this for either divisible or indivisible items. The impossibility results hold for public budgets, while the mechanism allows private budgets, which is in both cases the harder variant to show. While all positive results are polynomial-time algorithms, all negative results hold independent of complexity considerations.}, author = {Dütting, Paul and Henzinger, Monika H and Starnberger, Martin}, booktitle = {8th International Workshop on Internet and Network Economics}, isbn = {9783642353109}, issn = {1611-3349}, location = {Liverpool, United Kingdom}, pages = {44–57}, publisher = {Springer Nature}, title = {{Auctions with heterogeneous items and budget limits}}, doi = {10.1007/978-3-642-35311-6_4}, volume = {7695}, year = {2012}, } @inproceedings{11795, abstract = {We study multiple keyword sponsored search auctions with budgets. Each keyword has multiple ad slots with a click-through rate. The bidders have additive valuations, which are linear in the click-through rates, and budgets, which are restricting their overall payments. Additionally, the number of slots per keyword assigned to a bidder is bounded. We show the following results: (1) We give the first mechanism for multiple keywords, where click-through rates differ among slots. Our mechanism is incentive compatible in expectation, individually rational in expectation, and Pareto optimal. (2) We study the combinatorial setting, where each bidder is only interested in a subset of the keywords. We give an incentive compatible, individually rational, Pareto optimal, and deterministic mechanism for identical click-through rates. (3) We give an impossibility result for incentive compatible, individually rational, Pareto optimal, and deterministic mechanisms for bidders with diminishing marginal valuations.}, author = {Colini-Baldeschi, Riccardo and Henzinger, Monika H and Leonardi, Stefano and Starnberger, Martin}, booktitle = {39th International Colloquium on Automata, Languages, and Programming}, isbn = {9783642315848}, issn = {0302-9743}, location = {Warwick, United Kingdom}, pages = {1–12}, publisher = {Springer Nature}, title = {{On multiple keyword sponsored search auctions with budgets}}, doi = {10.1007/978-3-642-31585-5_1}, volume = {7392}, year = {2012}, } @article{11963, abstract = {Peroxides and ethers in flow: 2-Carbonyl-substituted phenols and β-ketoesters react safely with ethers in a microreactor environment using a copper catalyst and an organic peroxide (TBHP). This protocol results in unsymmetrical acetal scaffolds not easily available otherwise (see scheme).}, author = {Kumar, G. Sathish and Pieber, Bartholomäus and Reddy, K. Rajender and Kappe, C. Oliver}, issn = {1521-3765}, journal = {Chemistry - A European Journal}, number = {20}, pages = {6124--6128}, publisher = {Wiley}, title = {{Copper-catalyzed formation of C-O bonds by direct α-C-H bond activation of ethers using stoichiometric amounts of peroxide in batch and continuous-flow formats}}, doi = {10.1002/chem.201200815}, volume = {18}, year = {2012}, } @article{11964, abstract = {A detailed investigation on the direct arylation of benzene with aryl bromides by using first-row transition metals under high-temperature/high-pressure (high-T/p) conditions is described. By employing a parallel reactor platform for rapid reaction screening and discovery at elevated temperatures, various metal/ligand/base combinations were evaluated for their ability to enable biaryl formation through C-H activation. The combination of cobalt(III) acetylacetonate and lithium bis(trimethylsilyl)amide was subjected to further process intensification at 200 °C (15 bar), allowing a significant reduction of the catalyst/base loading and a dramatic increase in catalytic efficiency (turnover frequency) by a factor of 1000 compared to traditional protocols. The high-throughput screening additionally identified novel nickel- and copper-based metal/ligand combinations that favored an amination pathway competing with C-H activation, with the addition of ligands, such as 1,10-phenanthroline, having a profound influence on the selectivity. In addition to metal-based catalysts, high-T/p process windows were also successfully applied to transition-metal-free systems, utilizing 1,10-phenanthroline as organocatalyst.}, author = {Pieber, Bartholomäus and Cantillo, David and Kappe, C. Oliver}, issn = {1521-3765}, journal = {Chemistry – A European Journal}, number = {16}, pages = {5047--5055}, publisher = {Wiley}, title = {{Direct arylation of benzene with aryl bromides using high‐temperature/high‐pressure process windows: Expanding the scope of C-H activation chemistry}}, doi = {10.1002/chem.201103748}, volume = {18}, year = {2012}, } @article{12198, abstract = {The Arabidopsis thaliana central cell, the companion cell of the egg, undergoes DNA demethylation before fertilization, but the targeting preferences, mechanism, and biological significance of this process remain unclear. Here, we show that active DNA demethylation mediated by the DEMETER DNA glycosylase accounts for all of the demethylation in the central cell and preferentially targets small, AT-rich, and nucleosome-depleted euchromatic transposable elements. The vegetative cell, the companion cell of sperm, also undergoes DEMETER-dependent demethylation of similar sequences, and lack of DEMETER in vegetative cells causes reduced small RNA–directed DNA methylation of transposons in sperm. Our results demonstrate that demethylation in companion cells reinforces transposon methylation in plant gametes and likely contributes to stable silencing of transposable elements across generations.}, author = {Ibarra, Christian A. and Feng, Xiaoqi and Schoft, Vera K. and Hsieh, Tzung-Fu and Uzawa, Rie and Rodrigues, Jessica A. and Zemach, Assaf and Chumak, Nina and Machlicova, Adriana and Nishimura, Toshiro and Rojas, Denisse and Fischer, Robert L. and Tamaru, Hisashi and Zilberman, Daniel}, issn = {1095-9203}, journal = {Science}, keywords = {Multidisciplinary}, number = {6100}, pages = {1360--1364}, publisher = {American Association for the Advancement of Science}, title = {{Active DNA demethylation in plant companion cells reinforces transposon methylation in gametes}}, doi = {10.1126/science.1224839}, volume = {337}, year = {2012}, } @article{2687, abstract = {Left-right asymmetry of human brain function has been known for a century, although much of molecular and cellular basis of brain laterality remains to be elusive. Recent studies suggest that hippocampal CA3-CA1 excitatory synapses are asymmetrically arranged, however, the functional implication of the asymmetrical circuitry has not been studied at the behavioral level. In order to address the left-right asymmetry of hippocampal function in behaving mice, we analyzed the performance of "split-brain" mice in the Barnes maze. The "split-brain" mice received ventral hippocampal commissure and corpus callosum transection in addition to deprivation of visual input from one eye. In such mice, the hippocampus in the side of visual deprivation receives sensory-driven input. Better spatial task performance was achieved by the mice which were forced to use the right hippocampus than those which were forced to use the left hippocampus. In two-choice spatial maze, forced usage of left hippocampus resulted in a comparable performance to the right counterpart, suggesting that both hippocampal hemispheres are capable of conducting spatial learning. Therefore, the results obtained from the Barnes maze suggest that the usage of the right hippocampus improves the accuracy of spatial memory. Performance of non-spatial yet hippocampus-dependent tasks (e.g. fear conditioning) was not influenced by the laterality of the hippocampus.}, author = {Shinohara, Yoshiaki and Hosoya, Aki and Yamasaki, Nobuyuki and Ahmed, Hassan and Hattori, Satoko and Eguchi, Megumi and Yamaguchi, Shun and Miyakawa, Tsuyoshi and Hirase, Hajime and Ryuichi Shigemoto}, journal = {Hippocampus}, number = {2}, pages = {117 -- 121}, publisher = {Wiley-Blackwell}, title = {{Right-hemispheric dominance of spatial memory in split-brain mice}}, doi = {10.1002/hipo.20886}, volume = {22}, year = {2012}, } @article{2688, abstract = {To gain insights into structure-function relationship of excitatory synapses, we revisit our quantitative analysis of synaptic AMPAR by highly sensitive freeze-fracture replica labeling in eight different connections. All of these connections showed linear correlation between synapse size and AMPAR number indicating a common intra-synapse-type relationship in CNS synapses. On the contrary, inter-synapse-type relationship is unexpected indicating no correlation between averages of synapse size and AMPAR number. Interestingly, connections with large average synapse size and low AMPAR density showed high variability of AMPAR number and mosaic distribution within the postsynaptic membrane. We propose an idea that these connections may quickly exhibit synaptic plasticity by modifying AMPAR density/number whereas those with high AMPAR density change their efficacy by modifying synapse size.}, author = {Fukazawa, Yugo and Ryuichi Shigemoto}, journal = {Current Opinion in Neurobiology}, number = {3}, pages = {446 -- 452}, publisher = {Elsevier}, title = {{Intra-synapse-type and inter-synapse-type relationships between synaptic size and AMPAR expression}}, doi = {10.1016/j.conb.2012.01.006}, volume = {22}, year = {2012}, } @article{2689, abstract = {R-type calcium channels (RTCCs) are well known for their role in synaptic plasticity, but little is known about their subcellular distribution across various neuronal compartments. Using subtype-specific antibodies, we characterized the regional and subcellular localization of Ca v2.3 in mice and rats at both light and electron microscopic levels. Ca v2.3 immunogold particles were found to be predominantly presynaptic in the interpeduncular nucleus, but postsynaptic in other brain regions. Serial section analysis of electron microscopic images from the hippocampal CA1 revealed a higher density of immunogold particles in the dendritic shaft plasma membrane compared with the pyramidal cell somata. However, the labeling densities were not significantly different among the apical, oblique, or basal dendrites. Immunogold particles were also observed over the plasma membrane of dendritic spines, including both synaptic and extrasynaptic sites. Individual spine heads contained <20 immunogold particles, with an average density of ~260 immunoparticles per μm 3 spine head volume, in accordance with the density of RTCCs estimated using calcium imaging (Sabatini and Svoboda, 2000). The Ca v2.3 density was variable among similar-sized spine heads and did not correlate with the density in the parent dendrite, implying that spines are individual calcium compartments operating autonomously from their parent dendrites.}, author = {Parajuli, Laxmi K and Nakajima, Chikako and Kulik, Ákos and Matsui, Ko and Schneider, Toni and Ryuichi Shigemoto and Fukazawa, Yugo}, journal = {Journal of Neuroscience}, number = {39}, pages = {13555 -- 13567}, publisher = {Society for Neuroscience}, title = {{Quantitative regional and ultra structural localization of the Ca v2 3 subunit of R type calcium channel in mouse brain}}, doi = {10.1523/JNEUROSCI.1142-12.2012}, volume = {32}, year = {2012}, } @unpublished{2696, author = {László Erdös}, booktitle = {ArXiv}, publisher = {ArXiv}, title = {{Universality for random matrices and log-gases}}, year = {2012}, } @inproceedings{2700, author = {László Erdös}, pages = {3 -- 98}, publisher = {Oxford University Press}, title = {{Lecture notes on quantum Brownian motion}}, volume = {95}, year = {2012}, } @inproceedings{2715, abstract = {We consider Markov decision processes (MDPs) with specifications given as Büchi (liveness) objectives. We consider the problem of computing the set of almost-sure winning vertices from where the objective can be ensured with probability 1. We study for the first time the average case complexity of the classical algorithm for computing the set of almost-sure winning vertices for MDPs with Büchi objectives. Our contributions are as follows: First, we show that for MDPs with constant out-degree the expected number of iterations is at most logarithmic and the average case running time is linear (as compared to the worst case linear number of iterations and quadratic time complexity). Second, for the average case analysis over all MDPs we show that the expected number of iterations is constant and the average case running time is linear (again as compared to the worst case linear number of iterations and quadratic time complexity). Finally we also show that given that all MDPs are equally likely, the probability that the classical algorithm requires more than constant number of iterations is exponentially small.}, author = {Chatterjee, Krishnendu and Joglekar, Manas and Shah, Nisarg}, location = {Hyderabad, India}, pages = {461 -- 473}, publisher = {Schloss Dagstuhl - Leibniz-Zentrum für Informatik}, title = {{Average case analysis of the classical algorithm for Markov decision processes with Büchi objectives}}, doi = {10.4230/LIPIcs.FSTTCS.2012.461}, volume = {18}, year = {2012}, }