TY - JOUR
AB - Circumferential skin creases Kunze type (CSC-KT) is a specific congenital entity with an unknown genetic cause. The disease phenotype comprises characteristic circumferential skin creases accompanied by intellectual disability, a cleft palate, short stature, and dysmorphic features. Here, we report that mutations in either MAPRE2 or TUBB underlie the genetic origin of this syndrome. MAPRE2 encodes a member of the microtubule end-binding family of proteins that bind to the guanosine triphosphate cap at growing microtubule plus ends, and TUBB encodes a β-tubulin isotype that is expressed abundantly in the developing brain. Functional analyses of the TUBB mutants show multiple defects in the chaperone-dependent tubulin heterodimer folding and assembly pathway that leads to a compromised yield of native heterodimers. The TUBB mutations also have an impact on microtubule dynamics. For MAPRE2, we show that the mutations result in enhanced MAPRE2 binding to microtubules, implying an increased dwell time at microtubule plus ends. Further, in vivo analysis of MAPRE2 mutations in a zebrafish model of craniofacial development shows that the variants most likely perturb the patterning of branchial arches, either through excessive activity (under a recessive paradigm) or through haploinsufficiency (dominant de novo paradigm). Taken together, our data add CSC-KT to the growing list of tubulinopathies and highlight how multiple inheritance paradigms can affect dosage-sensitive biological systems so as to result in the same clinical defect.
AU - Isrie, Mala
AU - Breuss, Martin
AU - Tian, Guoling
AU - Hansen, Andi H
AU - Cristofoli, Francesca
AU - Morandell, Jasmin
AU - Kupchinsky, Zachari A
AU - Sifrim, Alejandro
AU - Rodriguez Rodriguez, Celia
AU - Dapena, Elena P
AU - Doonanco, Kurston
AU - Leonard, Norma
AU - Tinsa, Faten
AU - Moortgat, Stéphanie
AU - Ulucan, Hakan
AU - Koparir, Erkan
AU - Karaca, Ender
AU - Katsanis, Nicholas
AU - Marton, Valeria
AU - Vermeesch, Joris R
AU - Davis, Erica E
AU - Cowan, Nicholas J
AU - Keays, David
AU - Van Esch, Hilde
ID - 1106
IS - 6
JF - The American Journal of Human Genetics
TI - Mutations in either TUBB or MAPRE2 cause circumferential skin creases Kunze type
VL - 97
ER -
TY - JOUR
AB - We present a hybrid intercalation battery based on a sodium/magnesium (Na/Mg) dual salt electrolyte, metallic magnesium anode, and a cathode based on FeS2 nanocrystals (NCs). Compared to lithium or sodium, metallic magnesium anode is safer due to dendrite-free electroplating and offers extremely high volumetric (3833 mAh cm-3) and gravimetric capacities (2205 mAh g-1). Na-ion cathodes, FeS2 NCs in the present study, may serve as attractive alternatives to Mg-ion cathodes due to the higher voltage of operation and fast, highly reversible insertion of Na-ions. In this proof-of-concept study, electrochemical cycling of the Na/Mg hybrid battery was characterized by high rate capability, high Coulombic efficiency of 99.8%, and high energy density. In particular, with an average discharge voltage of ∼1.1 V and a cathodic capacity of 189 mAh g-1 at a current of 200 mA g-1, the presented Mg/FeS2 hybrid battery delivers energy densities of up to 210 Wh kg-1, comparable to commercial Li-ion batteries and approximately twice as high as state-of-the-art Mg-ion batteries based on Mo6S8 cathodes. Further significant gains in the energy density are expected from the development of Na/Mg electrolytes with a broader electrochemical stability window. Fully based on Earth-abundant elements, hybrid Na-Mg batteries are highly promising for large-scale stationary energy storage.
AU - Walter, Marc
AU - Kravchyk, Kostiantyn
AU - Ibáñez, Maria
AU - Kovalenko, Maksym
ID - 333
IS - 21
JF - Chemistry of Materials
TI - Efficient and inexpensive sodium magnesium hybrid battery
VL - 27
ER -
TY - JOUR
AB - A cation exchange-based route was used to produce Cu2ZnSnS4 (CZTS)-Ag2S nanoparticles with controlled composition. We report a detailed study of the formation of such CZTS-Ag2S nanoheterostructures and of their photocatalytic properties. When compared to pure CZTS, the use of nanoscale p-n heterostructures as light absorbers for photocatalytic water splitting provides superior photocurrents. We associate this experimental fact to a higher separation efficiency of the photogenerated electron-hole pairs. We believe this and other type-II nanoheterostructures will open the door to the use of CZTS, with excellent light absorption properties and made of abundant and environmental friendly elements, to the field of photocatalysis.
AU - Yu, Xuelian
AU - Liu, Jingjing
AU - Genç, Aziz
AU - Ibáñez, Maria
AU - Luo, Zhishan
AU - Shavel, Alexey
AU - Arbiol, Jordi
AU - Zhang, Guangjin
AU - Zhang, Yihe
AU - Cabot, Andreu
ID - 334
IS - 38
JF - Langmuir
TI - Cu2ZnSnS4–Ag2S Nanoscale p–n heterostructures as sensitizers for photoelectrochemical water splitting
VL - 31
ER -
TY - JOUR
AB - A simple and effective method to introduce precise amounts of doping in nanomaterials produced from the bottom-up assembly of colloidal nanoparticles (NPs) is described. The procedure takes advantage of a ligand displacement step to incorporate controlled concentrations of halide ions while removing carboxylic acids from the NP surface. Upon consolidation of the NPs into dense pellets, halide ions diffuse within the crystal structure, doping the anion sublattice and achieving n-type electrical doping. Through the characterization of the thermoelectric properties of nanocrystalline PbS, we demonstrate this strategy to be effective to control charge transport properties on thermoelectric nanomaterials assembled from NP building blocks. This approach is subsequently extended to PbTexSe1-x@PbS core-shell NPs, where a significant enhancement of the thermoelectric figure of merit is achieved.
AU - Ibáñez, Maria
AU - Korkosz, Rachel
AU - Luo, Zhishan
AU - Riba, Pau
AU - Cadavid, Doris
AU - Ortega, Silvia
AU - Cabot, Andreu
AU - Kanatzidis, Mercouri
ID - 354
IS - 12
JF - Journal of the American Chemical Society
TI - Electron doping in bottom up engineered thermoelectric nanomaterials through HCl mediated ligand displacement
VL - 137
ER -
TY - JOUR
AB - We report the synthesis and photocatalytic and magnetic characterization of colloidal nanoheterostructures formed by combining a Pt-based magnetic metal alloy (PtCo, PtNi) with Cu2ZnSnS4 (CZTS). While CZTS is one of the main candidate materials for solar energy conversion, the introduction of a Pt-based alloy on its surface strongly influences its chemical and electronic properties, ultimately determining its functionality. In this regard, up to a 15-fold increase of the photocatalytic hydrogen evolution activity was obtained with CZTS–PtCo when compared with CZTS. Furthermore, two times higher hydrogen evolution rates were obtained for CZTS–PtCo when compared with CZTS–Pt, in spite of the lower precious metal loading of the former. Besides, the magnetic properties of the PtCo nanoparticles attached to the CZTS nanocrystals were retained in the heterostructures, which could facilitate catalyst purification and recovery for its posterior recycling and/or reutilization.
AU - Yu, Xuelian
AU - An, Xiaoqiang
AU - Genç, Aziz
AU - Ibáñez, Maria
AU - Arbiol, Jordi
AU - Zhang, Yihe
AU - Cabot, Andreu
ID - 361
IS - 38
JF - Journal of Physical Chemistry C
TI - Cu2ZnSnS4–PtM (M = Co, Ni) nanoheterostructures for photocatalytic hydrogen evolution
VL - 119
ER -
TY - JOUR
AB - A cation exchange-based route was used to produce Cu2ZnSnS4 (CZTS)-Ag2S nanoparticles with controlled composition. We report a detailed study of the formation of such CZTS-Ag2S nanoheterostructures and of their photocatalytic properties. When compared to pure CZTS, the use of nanoscale p-n heterostructures as light absorbers for photocatalytic water splitting provides superior photocurrents. We associate this experimental fact to a higher separation efficiency of the photogenerated electron-hole pairs. We believe this and other type-II nanoheterostructures will open the door to the use of CZTS, with excellent light absorption properties and made of abundant and environmental friendly elements, to the field of photocatalysis.
AU - Yu, Xuelian
AU - Liu, Jingjing
AU - Genç, Aziz
AU - Ibáñez, Maria
AU - Luo, Zhishan
AU - Shavel, Alexey
AU - Arbiol, Jordi
AU - Zhang, Guangjin
AU - Zhang, Yihe
AU - Cabot, Andreu
ID - 360
IS - 38
JF - Langmuir
TI - Cu2ZnSnS4-Ag2S nanoscale p-n heterostructures as sensitizers for photoelectrochemical water splitting
VL - 31
ER -
TY - JOUR
AB - We use ultrafast optical spectroscopy to observe binding of charged single-particle excitations (SE) in the magnetically frustrated Mott insulator Na2IrO3. Above the antiferromagnetic ordering temperature (TN) the system response is due to both Hubbard excitons (HE) and their constituent unpaired SE. The SE response becomes strongly suppressed immediately below TN. We argue that this increase in binding energy is due to a unique interplay between the frustrated Kitaev and the weak Heisenberg-type ordering term in the Hamiltonian, mediating an effective interaction between the spin-singlet SE. This interaction grows with distance causing the SE to become trapped in the HE, similar to quark confinement inside hadrons. This binding of charged particles, induced by magnetic ordering, is a result of a confinement-deconfinement transition of spin excitations. This observation provides evidence for spin liquid type behavior which is expected in Na2IrO3.
AU - Alpichshev, Zhanybek
AU - Mahmood, Fahad
AU - Cao, Gang
AU - Gedik, Nuh
ID - 388
IS - 1
JF - Physical Review Letters
TI - Confinement deconfinement transition as an indication of spin liquid type behavior in Na2IrO3
VL - 114
ER -
TY - JOUR
AB - Monodisperse Pd2Sn nanorods with tuned size and aspect ratio were prepared by co-reduction of metal salts in the presence of trioctylphosphine, amine, and chloride ions. Asymmetric Pd2Sn nanostructures were achieved by the selective desorption of a surfactant mediated by chlorine ions. A preliminary evaluation of the geometry influence on catalytic properties evidenced Pd2Sn nanorods to have improved catalytic performance. In view of these results, Pd2Sn nanorods were also evaluated for water denitration.
AU - Lu, Zhishan
AU - Ibáñez, Maria
AU - Antolín, Ana
AU - Genç, Aziz
AU - Shavel, Alexey
AU - Contreras, Sandra
AU - Medina, Francesc
AU - Arbiol, Jordi
AU - Cabot, Andreu
ID - 362
IS - 13
JF - Langmuir
TI - Size and aspect ratio control of Pd inf 2 inf Sn nanorods and their water denitration properties
VL - 31
ER -
TY - CONF
AB - In this work, we consider the following random process, mo- Tivated by the analysis of lock-free concurrent algorithms under high memory contention. In each round, a new scheduling step is allocated to one of n threads, according to a distribution p = (p1; p2; : : : ; pn), where thread i is scheduled with probability pi. When some thread first reaches a set threshold of executed steps, it registers a win, completing its current operation, and resets its step count to 1. At the same time, threads whose step count was close to the threshold also get reset because of the win, but to 0 steps, being penalized for almost winning. We are interested in two questions: how often does some thread complete an operation (system latency), and how often does a specific thread complete an operation (individual latency)? We provide asymptotically tight bounds for the system and individual latency of this general concurrency pattern, for arbitrary scheduling distributions p. Surprisingly, a sim- ple characterization exists: in expectation, the system will complete a new operation every Θ(1/p 2) steps, while thread i will complete a new operation every Θ(1/2=p i ) steps. The proof is interesting in its own right, as it requires a careful analysis of how the higher norms of the vector p inuence the thread step counts and latencies in this random process. Our result offers a simple connection between the scheduling distribution and the average performance of concurrent algorithms, which has several applications.
AU - Alistarh, Dan-Adrian
AU - Sauerwald, Thomas
AU - Vojnović, Milan
ID - 782
TI - Lock-Free algorithms under stochastic schedulers
VL - 2015-July
ER -
TY - CONF
AB - High-performance concurrent priority queues are essential for applications such as task scheduling and discrete event simulation. Unfortunately, even the best performing implementations do not scale past a number of threads in the single digits. This is because of the sequential bottleneck in accessing the elements at the head of the queue in order to perform a DeleteMin operation. In this paper, we present the SprayList, a scalable priority queue with relaxed ordering semantics. Starting from a non-blocking SkipList, the main innovation behind our design is that the DeleteMin operations avoid a sequential bottleneck by "spraying" themselves onto the head of the SkipList list in a coordinated fashion. The spraying is implemented using a carefully designed random walk, so that DeleteMin returns an element among the first O(plog3p) in the list, with high probability, where p is the number of threads. We prove that the running time of a DeleteMin operation is O(log3p), with high probability, independent of the size of the list. Our experiments show that the relaxed semantics allow the data structure to scale for high thread counts, comparable to a classic unordered SkipList. Furthermore, we observe that, for reasonably parallel workloads, the scalability benefits of relaxation considerably outweigh the additional work due to out-of-order execution.
AU - Alistarh, Dan-Adrian
AU - Kopinsky, Justin
AU - Li, Jerry
AU - Shavit, Nir
ID - 776
TI - The SprayList: A scalable relaxed priority queue
VL - 2015-January
ER -
TY - CONF
AB - The problem of electing a leader from among n contenders is one of the fundamental questions in distributed computing. In its simplest formulation, the task is as follows: given n processors, all participants must eventually return a win or lose indication, such that a single contender may win. Despite a considerable amount of work on leader election, the following question is still open: can we elect a leader in an asynchronous fault-prone system faster than just running a Θ(log n)-time tournament, against a strong adaptive adversary? In this paper, we answer this question in the affirmative, improving on a decades-old upper bound. We introduce two new algorithmic ideas to reduce the time complexity of electing a leader to O(log∗ n), using O(n2) point-to-point messages. A non-trivial application of our algorithm is a new upper bound for the tight renaming problem, assigning n items to the n participants in expected O(log2 n) time and O(n2) messages. We complement our results with lower bound of Ω(n2) messages for solving these two problems, closing the question of their message complexity.
AU - Alistarh, Dan-Adrian
AU - Gelashvili, Rati
AU - Vladu, Adrian
ID - 783
TI - How to elect a leader faster than a tournament
VL - 2015-July
ER -
TY - CONF
AB - Population protocols, roughly defined as systems consisting of large numbers of simple identical agents, interacting at random and updating their state following simple rules, are an important research topic at the intersection of distributed computing and biology. One of the fundamental tasks that a population protocol may solve is majority: each node starts in one of two states; the goal is for all nodes to reach a correct consensus on which of the two states was initially the majority. Despite considerable research effort, known protocols for this problem are either exact but slow (taking linear parallel time to converge), or fast but approximate (with non-zero probability of error). In this paper, we show that this trade-off between preciasion and speed is not inherent. We present a new protocol called Average and Conquer (AVC) that solves majority ex-actly in expected parallel convergence time O(log n/(sε) + log n log s), where n is the number of nodes, εn is the initial node advantage of the majority state, and s = Ω(log n log log n) is the number of states the protocol employs. This shows that the majority problem can be solved exactly in time poly-logarithmic in n, provided that the memory per node is s = Ω(1/ε + lognlog1/ε). On the negative side, we establish a lower bound of Ω(1/ε) on the expected paraallel convergence time for the case of four memory states per node, and a lower bound of Ω(logn) parallel time for protocols using any number of memory states per node.per node, and a lower bound of (log n) parallel time for protocols using any number of memory states per node.
AU - Alistarh, Dan-Adrian
AU - Gelashvili, Rati
AU - Vojnović, Milan
ID - 781
TI - Fast and exact majority in population protocols
VL - 2015-July
ER -
TY - CONF
AB - The concurrent memory reclamation problem is that of devising a way for a deallocating thread to verify that no other concurrent threads hold references to a memory block being deallocated. To date, in the absence of automatic garbage collection, there is no satisfactory solution to this problem; existing tracking methods like hazard pointers, reference counters, or epoch-based techniques like RCU, are either prohibitively expensive or require significant programming expertise, to the extent that implementing them efficiently can be worthy of a publication. None of the existing techniques are automatic or even semi-automated. In this paper, we take a new approach to concurrent memory reclamation: instead of manually tracking access to memory locations as done in techniques like hazard pointers, or restricting shared accesses to specific epoch boundaries as in RCU, our algorithm, called ThreadScan, leverages operating system signaling to automatically detect which memory locations are being accessed by concurrent threads. Initial empirical evidence shows that ThreadScan scales surprisingly well and requires negligible programming effort beyond the standard use of Malloc and Free.
AU - Alistarh, Dan-Adrian
AU - Matveev, Alexander
AU - Leiserson, William
AU - Shavit, Nir
ID - 779
TI - ThreadScan: Automatic and scalable memory reclamation
VL - 2015-June
ER -
TY - CONF
AB - In many applications, the data is of rich structure that can be represented by a hypergraph, where the data items are represented by vertices and the associations among items are represented by hyperedges. Equivalently, we are given an input bipartite graph with two types of vertices: items, and associations (which we refer to as topics). We consider the problem of partitioning the set of items into a given number of components such that the maximum number of topics covered by a component is minimized. This is a clustering problem with various applications, e.g. partitioning of a set of information objects such as documents, images, and videos, and load balancing in the context of modern computation platforms.Inthis paper, we focus on the streaming computation model for this problem, in which items arrive online one at a time and each item must be assigned irrevocably to a component at its arrival time. Motivated by scalability requirements, we focus on the class of streaming computation algorithms with memory limited to be at most linear in the number of components. We show that a greedy assignment strategy is able to recover a hidden co-clustering of items under a natural set of recovery conditions. We also report results of an extensive empirical evaluation, which demonstrate that this greedy strategy yields superior performance when compared with alternative approaches.
AU - Alistarh, Dan-Adrian
AU - Iglesias, Jennifer
AU - Vojnović, Milan
ID - 777
TI - Streaming min-max hypergraph partitioning
VL - 2015-January
ER -
TY - JOUR
AB - An essential question of morphogenesis is how patterns arise without preexisting positional information, as inspired by Turing. In the past few years, cytoskeletal flows in the cell cortex have been identified as a key mechanism of molecular patterning at the subcellular level. Theoretical and in vitro studies have suggested that biological polymers such as actomyosin gels have the property to self-organize, but the applicability of this concept in an in vivo setting remains unclear. Here, we report that the regular spacing pattern of supracellular actin rings in the Drosophila tracheal tubule is governed by a self-organizing principle. We propose a simple biophysical model where pattern formation arises from the interplay of myosin contractility and actin turnover. We validate the hypotheses of the model using photobleaching experiments and report that the formation of actin rings is contractility dependent. Moreover, genetic and pharmacological perturbations of the physical properties of the actomyosin gel modify the spacing of the pattern, as the model predicted. In addition, our model posited a role of cortical friction in stabilizing the spacing pattern of actin rings. Consistently, genetic depletion of apical extracellular matrix caused strikingly dynamic movements of actin rings, mirroring our model prediction of a transition from steady to chaotic actin patterns at low cortical friction. Our results therefore demonstrate quantitatively that a hydrodynamical instability of the actin cortex can trigger regular pattern formation and drive morphogenesis in an in vivo setting.
AU - Hannezo, Edouard B
AU - Dong, Bo
AU - Recho, Pierre
AU - Joanny, Jean
AU - Hayashi, Shigeo
ID - 929
IS - 28
JF - PNAS
TI - Cortical instability drives periodic supracellular actin pattern formation in epithelial tubes
VL - 112
ER -
TY - JOUR
AB - This paper presents a numerical study of a Capillary Pumped Loop evaporator. A two-dimensional unsteady mathematical model of a flat evaporator is developed to simulate heat and mass transfer in unsaturated porous wick with phase change. The liquid-vapor phase change inside the porous wick is described by Langmuir's law. The governing equations are solved by the Finite Element Method. The results are presented then for a sintered nickel wick and methanol as a working fluid. The heat flux required to the transition from the all-liquid wick to the vapor-liquid wick is calculated. The dynamic and thermodynamic behavior of the working fluid in the capillary structure are discussed in this paper.
AU - Boubaker, Riadh
AU - Platel, Vincent
AU - Bergès, Alexis
AU - Bancelin, Mathieu
AU - Hannezo, Edouard B
ID - 924
JF - Applied Thermal Engineering
TI - Dynamic model of heat and mass transfer in an unsaturated porous wick of capillary pumped loop
VL - 76
ER -
TY - JOUR
AB - In the present note we announce a proof of a strong form of Arnold diffusion for smooth convex Hamiltonian systems. Let ${\mathbb T}^2$ be a 2-dimensional torus and B2 be the unit ball around the origin in ${\mathbb R}^2$ . Fix ρ > 0. Our main result says that for a 'generic' time-periodic perturbation of an integrable system of two degrees of freedom $H_0(p)+\varepsilon H_1(\theta,p,t),\quad \ \theta\in {\mathbb T}^2,\ p\in B^2,\ t\in {\mathbb T}={\mathbb R}/{\mathbb Z}$ , with a strictly convex H0, there exists a ρ-dense orbit (θε, pε, t)(t) in ${\mathbb T}^2 \times B^2 \times {\mathbb T}$ , namely, a ρ-neighborhood of the orbit contains ${\mathbb T}^2 \times B^2 \times {\mathbb T}$ .
Our proof is a combination of geometric and variational methods. The fundamental elements of the construction are the usage of crumpled normally hyperbolic invariant cylinders from [9], flower and simple normally hyperbolic invariant manifolds from [36] as well as their kissing property at a strong double resonance. This allows us to build a 'connected' net of three-dimensional normally hyperbolic invariant manifolds. To construct diffusing orbits along this net we employ a version of the Mather variational method [41] equipped with weak KAM theory [28], proposed by Bernard in [7].
AU - Kaloshin, Vadim
AU - Zhang, K
ID - 8498
IS - 8
JF - Nonlinearity
KW - Mathematical Physics
KW - General Physics and Astronomy
KW - Applied Mathematics
KW - Statistical and Nonlinear Physics
SN - 0951-7715
TI - Arnold diffusion for smooth convex systems of two and a half degrees of freedom
VL - 28
ER -
TY - JOUR
AB - In this note, we consider the dynamics associated to a perturbation of an integrable Hamiltonian system in action-angle coordinates in any number of degrees of freedom and we prove the following result of ``micro-diffusion'': under generic assumptions on $ h$ and $ f$, there exists an orbit of the system for which the drift of its action variables is at least of order $ \sqrt {\varepsilon }$, after a time of order $ \sqrt {\varepsilon }^{-1}$. The assumptions, which are essentially minimal, are that there exists a resonant point for $ h$ and that the corresponding averaged perturbation is non-constant. The conclusions, although very weak when compared to usual instability phenomena, are also essentially optimal within this setting.
AU - Bounemoura, Abed
AU - Kaloshin, Vadim
ID - 8495
IS - 4
JF - Proceedings of the American Mathematical Society
SN - 0002-9939
TI - A note on micro-instability for Hamiltonian systems close to integrable
VL - 144
ER -
TY - JOUR
AB - We consider the cubic defocusing nonlinear Schrödinger equation in the two dimensional torus. Fix s>1. Recently Colliander, Keel, Staffilani, Tao and Takaoka proved the existence of solutions with s-Sobolev norm growing in time.
We establish the existence of solutions with polynomial time estimates. More exactly, there is c>0 such that for any K≫1 we find a solution u and a time T such that ∥u(T)∥Hs≥K∥u(0)∥Hs. Moreover, the time T satisfies the polynomial bound 0