TY - JOUR AB - We report numerical simulations of membrane tubulation driven by large colloidal particles. Using Monte Carlo simulations we study how the process depends on particle size and binding strength, and present accurate free energy calculations to sort out how tube formation compares with the competing budding process. We find that tube formation is a result of the collective behavior of the particles adhering on the surface, and it occurs for binding strengths that are smaller than those required for budding. We also find that long linear aggregates of particles forming on the membrane surface act as nucleation seeds for tubulation by lowering the free energy barrier associated to the process. AU - Šarić, Anđela AU - Cacciuto, Angelo ID - 10387 IS - 18 JF - Physical Review Letters KW - general physics and astronomy SN - 0031-9007 TI - Mechanism of membrane tube formation induced by adhesive nanocomponents VL - 109 ER - TY - JOUR AB - Using computer simulations, we show that lipid membranes can mediate linear aggregation of spherical nanoparticles binding to it for a wide range of biologically relevant bending rigidities. This result is in net contrast with the isotropic aggregation of nanoparticles on fluid interfaces or the expected clustering of isotropic insertions in biological membranes. We present a phase diagram indicating where linear aggregation is expected and compute explicitly the free-energy barriers associated with linear and isotropic aggregation. Finally, we provide simple scaling arguments to explain this phenomenology. AU - Šarić, Anđela AU - Cacciuto, Angelo ID - 10388 IS - 11 JF - Physical Review Letters KW - general physics and astronomy SN - 0031-9007 TI - Fluid membranes can drive linear aggregation of adsorbed spherical nanoparticles VL - 108 ER - TY - JOUR AB - In July, 2011, a 32-year-old man presented with thoracic pain radiating to the left arm and upper dorsum, shortness of breath, and palpitations. He had had upper back tension for 6 months. Medical history was unremarkable apart from moderate nicotine use (two pack-years). Echocardiography, electrocardiography, and laboratory tests were unremarkable, excluding a cardiac event. CT of the chest after chest radiography showed a large bulla of 16 cm diameter in the right hemithorax (figure A). We did not detect radiological evidence of underlying pulmonary disease. The bulla wall was unremarkable and no structures were seen within the bulla. AU - Erne, Barbara AU - Graff, Mareike AU - Klemm, Wolfram AU - Danzl, Johann G AU - Leschber, Gunda ID - 1055 IS - 9849 JF - The Lancet TI - Bulla in the lung VL - 380 ER - TY - JOUR AB - We prepare and study a metastable attractive Mott-insulator state formed with bosonic atoms in a three-dimensional optical lattice. Starting from a Mott insulator with Cs atoms at weak repulsive interactions, we use a magnetic Feshbach resonance to tune the interactions to large attractive values and produce a metastable state pinned by attractive interactions with a lifetime on the order of 10 s. We probe the (de)excitation spectrum via lattice modulation spectroscopy, measuring the interaction dependence of two- and three-body bound-state energies. As a result of increased on-site three-body loss we observe resonance broadening and suppression of tunneling processes that produce three-body occupation. AU - Mark, Manfred AU - Haller, Elmar AU - Lauber, Katharina AU - Danzl, Johann G AU - Janisch, Alexander AU - Büchler, Hans AU - Daley, Andrew AU - Nägerl, Hanns ID - 1056 IS - 21 JF - Physical Review Letters TI - Preparation and spectroscopy of a metastable mott-insulator state with attractive interactions VL - 108 ER - TY - CONF AB - The goal of this work is to study the superconducting coherence length in the fluctuation regime in cuprate superconductors. In this work we present cantilever torque magnetometry measurements of micron-size BSCCO flakes patterned with arrays of nanometer scale rings or holes. Using ultrasensitive dynamic torque magnetometry, oscillations in magnetization are observed near Tc as a function of the applied magnetic flux threading the array. Special effort was made to detect the oscillations in magnetization at temperatures above Tc, where the Nernst effect and magnetization measurements suggest the possibility of pairing. To constrain the magnitude of the coherence length in the fluctuation regime, we will present the dependence of the amplitude of the h/2e period oscillations as a function of temperature and hole size. AU - Polshyn, Hryhoriy AU - Budakian, Raffi ID - 10750 IS - 1 SN - 0003-0503 T2 - APS March Meeting 2012 TI - Cantilever torque magnetometry study of multiply connected BSCCO arrays near Tc VL - 57 ER - TY - CHAP AB - Under physiological conditions the brain, via the purine salvage pathway, reuses the preformed purine bases hypoxanthine, derived from ATP degradation, and adenine (Ade), derived from polyamine synthesis, to restore its ATP pool. However, the massive degradation of ATP during ischemia, although providing valuable neuroprotective adenosine, results in the accumulation and loss of diffusible purine metabolites and thereby leads to a protracted reduction in the post-ischemic ATP pool size. In vivo, this may both limit the ability to deploy ATP-dependent reparative mechanisms and reduce the subsequent availability of adenosine, whilst in brain slices results in tissue with substantially lower levels of ATP than in vivo. In the present review, we describe the mechanisms by which brain tissue replenishes its ATP, how this can be improved with the clinically tolerated chemicals D-ribose and adenine, and the functional, and potential therapeutic, implications of doing so. AU - zur Nedden, Stephanie AU - Doney, Alexander S. AU - Frenguelli, Bruno G. ED - Masino, Susan ED - Boison, Detlev ID - 10896 SN - 9781461439028 T2 - Adenosine TI - The double-edged sword: Gaining Adenosine at the expense of ATP. How to balance the books ER - TY - JOUR AB - The Nuclear Envelope (NE) contains over 100 different proteins that associate with nuclear components such as chromatin, the lamina and the transcription machinery. Mutations in genes encoding NE proteins have been shown to result in tissue-specific defects and disease, suggesting cell-type specific differences in NE composition and function. Consistent with these observations, recent studies have revealed unexpected functions for numerous NE associated proteins during cell differentiation and development. Here we review the latest insights into the roles played by the NE in cell differentiation, development, disease and aging, focusing primarily on inner nuclear membrane (INM) proteins and nuclear pore components. AU - Gomez-Cavazos, J Sebastian AU - HETZER, Martin W ID - 11089 IS - 6 JF - Current Opinion in Cell Biology KW - Cell Biology SN - 0955-0674 TI - Outfits for different occasions: tissue-specific roles of Nuclear Envelope proteins VL - 24 ER - TY - JOUR AB - Neoplastic cells are often characterized by specific morphological abnormalities of the nuclear envelope (NE), which have been used for cancer diagnosis for more than a century. The NE is a double phospholipid bilayer that encapsulates the nuclear genome, regulates all nuclear trafficking of RNAs and proteins and prevents the passive diffusion of macromolecules between the nucleoplasm and the cytoplasm. Whether there is a consequence to the proper functioning of the cell and loss of structural integrity of the nucleus remains unclear. Using live cell imaging, we characterize a phenomenon wherein nuclei of several proliferating human cancer cell lines become temporarily ruptured during interphase. Strikingly, NE rupturing was associated with the mislocalization of nucleoplasmic and cytoplasmic proteins and, in the most extreme cases, the entrapment of cytoplasmic organelles in the nuclear interior. In addition, we observed the formation of micronuclei-like structures during interphase and the movement of chromatin out of the nuclear space. The frequency of these NE rupturing events was higher in cells in which the nuclear lamina, a network of intermediate filaments providing mechanical support to the NE, was not properly formed. Our data uncover the existence of a NE instability that has the potential to change the genomic landscape of cancer cells. AU - Vargas, Jesse D. AU - Hatch, Emily M. AU - Anderson, Daniel J. AU - HETZER, Martin W ID - 11091 IS - 1 JF - Nucleus KW - Cell Biology SN - 1949-1034 TI - Transient nuclear envelope rupturing during interphase in human cancer cells VL - 3 ER - TY - JOUR AB - Nuclear pore complexes (NPCs) are built from ∼30 different proteins called nucleoporins or Nups. Previous studies have shown that several Nups exhibit cell-type-specific expression and that mutations in NPC components result in tissue-specific diseases. Here we show that a specific change in NPC composition is required for both myogenic and neuronal differentiation. The transmembrane nucleoporin Nup210 is absent in proliferating myoblasts and embryonic stem cells (ESCs) but becomes expressed and incorporated into NPCs during cell differentiation. Preventing Nup210 production by RNAi blocks myogenesis and the differentiation of ESCs into neuroprogenitors. We found that the addition of Nup210 to NPCs does not affect nuclear transport but is required for the induction of genes that are essential for cell differentiation. Our results identify a single change in NPC composition as an essential step in cell differentiation and establish a role for Nup210 in gene expression regulation and cell fate determination. AU - D'Angelo, Maximiliano A. AU - Gomez-Cavazos, J. Sebastian AU - Mei, Arianna AU - Lackner, Daniel H. AU - HETZER, Martin W ID - 11093 IS - 2 JF - Developmental Cell KW - Developmental Biology KW - Cell Biology KW - General Biochemistry KW - Genetics and Molecular Biology KW - Molecular Biology SN - 1534-5807 TI - A change in nuclear pore complex composition regulates cell differentiation VL - 22 ER - TY - JOUR AB - To combat the functional decline of the proteome, cells use the process of protein turnover to replace potentially impaired polypeptides with new functional copies. We found that extremely long-lived proteins (ELLPs) did not turn over in postmitotic cells of the rat central nervous system. These ELLPs were associated with chromatin and the nuclear pore complex, the central transport channels that mediate all molecular trafficking in and out of the nucleus. The longevity of these proteins would be expected to expose them to potentially harmful metabolites, putting them at risk of accumulating damage over extended periods of time. Thus, it is possible that failure to maintain proper levels and functional integrity of ELLPs in nonproliferative cells might contribute to age-related deterioration in cell and tissue function. AU - Savas, Jeffrey N. AU - Toyama, Brandon H. AU - Xu, Tao AU - Yates, John R. AU - HETZER, Martin W ID - 11092 IS - 6071 JF - Science KW - Multidisciplinary SN - 0036-8075 TI - Extremely long-lived nuclear pore proteins in the rat brain VL - 335 ER - TY - JOUR AB - Nuclear export of mRNAs is thought to occur exclusively through nuclear pore complexes. In this issue of Cell, Speese et al. identify an alternate pathway for mRNA export in muscle cells where ribonucleoprotein complexes involved in forming neuromuscular junctions transit the nuclear envelope by fusing with and budding through the nuclear membrane. AU - Hatch, Emily M. AU - HETZER, Martin W ID - 11090 IS - 4 JF - Cell KW - General Biochemistry KW - Genetics and Molecular Biology SN - 0092-8674 TI - RNP export by nuclear envelope budding VL - 149 ER - TY - JOUR AB - Although liquids typically flow around intruding objects, a counterintuitive phenomenon occurs in dense suspensions of micrometre-sized particles: they become liquid-like when perturbed lightly, but harden when driven strongly. Rheological experiments have investigated how such thickening arises under shear, and linked it to hydrodynamic interactions or granular dilation. However, neither of these mechanisms alone can explain the ability of suspensions to generate very large, positive normal stresses under impact. To illustrate the phenomenon, such stresses can be large enough to allow a person to run across a suspension without sinking, and far exceed the upper limit observed under shear or extension. Here we show that these stresses originate from an impact-generated solidification front that transforms an initially compressible particle matrix into a rapidly growing jammed region, ultimately leading to extraordinary amounts of momentum absorption. Using high-speed videography, embedded force sensing and X-ray imaging, we capture the detailed dynamics of this process as it decelerates a metal rod hitting a suspension of cornflour (cornstarch) in water. We develop a model for the dynamic solidification and its effect on the surrounding suspension that reproduces the observed behaviour quantitatively. Our findings suggest that prior interpretations of the impact resistance as dominated by shear thickening need to be revisited. AU - Waitukaitis, Scott R AU - Jaeger, Heinrich ID - 113 IS - 7406 JF - Nature TI - Impact-activated solidification of dense suspensions via dynamic jamming fronts VL - 487 ER - TY - JOUR AB - We report on an investigation of the solidification of a cornstarch and water suspension during normal impact on its surface. We find that a finite time after impact, the suspension displays characteristics reminiscent of a solid, including localized stress transmission, the development of a yield stress, and some elastic energy storage. The time dependence of these characteristics depends on the thickness of the cornstarch layer, showing that the solidification is a dynamic process driven by the impacting object. These findings confirm previous speculations that rapidly applied normal stress transforms the normally fluid-like suspension into a temporarily jammed solid and draw a clear distinction between the effects of normal stress and shear stress in dense suspensions. AU - Waitukaitis, Scott R AU - Jaeger, Heinrich ID - 114 IS - 1E JF - Revista Cubana de Fisica TI - Solidification of a cornstarch and water suspension VL - 29 ER - TY - CONF AB - 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. AU - Dütting, Paul AU - Henzinger, Monika H AU - Weber, Ingmar ID - 11656 SN - 9781450311564 T2 - Proceedings of the 21st ACM international conference on Information and knowledge management TI - Maximizing revenue from strategic recommendations under decaying trust ER - TY - JOUR AB - 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. AU - Lukas, K. C. AU - Joshi, G. AU - Modic, Kimberly A AU - Ren, Z. F. AU - Opeil, C. P. ID - 11751 IS - 15 JF - Journal of Materials Science SN - 0022-2461 TI - Thermoelectric properties of Ho-doped Bi0.88Sb0.12 VL - 47 ER - TY - CONF AB - 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. AU - Dütting, Paul AU - Henzinger, Monika H AU - Starnberger, Martin ID - 11794 SN - 1611-3349 T2 - 8th International Workshop on Internet and Network Economics TI - Auctions with heterogeneous items and budget limits VL - 7695 ER - TY - CONF AB - 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. AU - Colini-Baldeschi, Riccardo AU - Henzinger, Monika H AU - Leonardi, Stefano AU - Starnberger, Martin ID - 11795 SN - 0302-9743 T2 - 39th International Colloquium on Automata, Languages, and Programming TI - On multiple keyword sponsored search auctions with budgets VL - 7392 ER - TY - JOUR AB - 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. AU - Pieber, Bartholomäus AU - Cantillo, David AU - Kappe, C. Oliver ID - 11964 IS - 16 JF - Chemistry – A European Journal SN - 0947-6539 TI - Direct arylation of benzene with aryl bromides using high‐temperature/high‐pressure process windows: Expanding the scope of C-H activation chemistry VL - 18 ER - TY - JOUR AB - 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). AU - Kumar, G. Sathish AU - Pieber, Bartholomäus AU - Reddy, K. Rajender AU - Kappe, C. Oliver ID - 11963 IS - 20 JF - Chemistry - A European Journal SN - 0947-6539 TI - 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 VL - 18 ER - TY - JOUR AB - In the Dry Andes of central Chile, summer water resources originate mostly from snowmelt and ice melt. We use the physically based, spatially distributed hydrological model TOPKAPI to study the exchange between glaciers and climate in the upper Aconcagua River Basin during the summer season and identify the model parameters that are robust and transferable and those that are more dependent on calibration. TOPKAPI has recently been adapted to incorporate an enhanced temperature index approach for snow and ice melting. We suggest a calibration procedure that allows calibration of parameters in three steps by separating parameters governing distinct processes. We evaluate the parameters' transferability in time and in space by applying the model at two spatial scales. TOPKAPI's ability to simulate the relevant processes is tested against meteorological, ablation, and glacier runoff data measured on Juncal Norte Glacier during two glacier ablation seasons. The model was applied successfully to the climatic setting of the Dry Andes once its parameters were recalibrated. We found a clear distinction between parameters that are stable in time and those that need recalibration. The parameters of the melt model are transferable from one season to the other, while the parameters governing the extrapolation of meteorological input data and the routing of glacier meltwater need recalibration from one season to the other. Sensitivity analysis revealed that the model is most sensitive to the temperature lapse rate governing the extrapolation of air temperature from point measurements to the glacier scale and to the melt parameter that multiplies the shortwave radiation balance. AU - Ragettli, S. AU - Pellicciotti, Francesca ID - 12644 IS - 3 JF - Water Resources Research SN - 0043-1397 TI - Calibration of a physically based, spatially distributed hydrological model in a glacierized basin: On the use of knowledge from glaciometeorological processes to constrain model parameters VL - 48 ER -