
Rahimian, M.; Rafieipour, M. H.; GhorbaniTanha, A. K.; MohammadiGhazi, Reza
An innovative variable stiffness device is proposed and investigated based on numerical simulations. The device, called a folding variable stiffness spring (FVSS), can be widely used, especially in tuned mass dampers (TMDs) with adaptive stiffness. An important characteristic of FVSS is its capability to change the stiffness between lower and upper bounds through a small change of distance between its supports. This special feature results in lower timelag errors and readjustment in shorter time intervals. The governing equations of the device are derived and simplified for a symmetrical FVSS with similar elements. This device is then used to control a...

Hasan, Anwarul; Paul, Arghya; Memic, Adnan; Khademhosseini, Ali
There is an immense need for tissue engineered blood vessels. However, current tissue engineering approaches still lack the ability to build native blood vessellike perfusable structures with multilayered vascular walls. This paper demonstrated a new method to fabricate trilayer biomimetic blood vessellike structures on a microfluidic platform using photocrosslinkable gelatin hydrogel. The presented method enables fabrication of physiological blood vessellike structures with mono, bi or trilayer vascular walls. The diameter of the vessels, the total thickness of the vessel wall and the thickness of each individual layer of the wall were independently controlled. The developed fabrication process is a simple...

Widhalm, Peter; Yang, Yingxiang; Ulm, Michael; Athavale, Shounak; Gonzalez, Marta C.
Massive and passive data such as cell phone traces provide samples of the whereabouts and movements of individuals. These are a potential source of information for models of daily activities in a city. The main challenge is that phone traces have low spatial precision and are sparsely sampled in time, which requires a precise set of techniques for mining hidden valuable information they contain. Here we propose a method to reveal activity patterns that emerge from cell phone data by analyzing relational signatures of activity time, duration, and land use. First, we present a method of how to detect stays...

de Jong, Gerard; Vierth, Inge; Tavasszy, Lori; BenAkiva, Moshe E.
The past decade has seen many new freight transport models for use in transport planning by public authorities. Some of these models have developed new concepts, such as logistics modules, inclusion of transshipments, storage and sourcing and the determination of shipment size. This paper provides a review of the European literature on freight transport models that operate at the national or international level and have been developed since 2004. The introduction of elements of logistics thinking is identified as a common theme in recently developed models, and further worked out. Furthermore, ideas on what might be the next key developments...

Kennedy, D.; Rubin, B. E. R.; Anderson, R. M.; Palmer, T. M.; Stanton, M. L.; Lovette, I. J.
Polygyny is common in social insects despite inevitable decreases in nestmate relatedness and reductions to the inclusive fitness returns for cooperating nonreproductive individuals. We studied the prevalence and mode of polygyny in the African acaciaant Crematogaster mimosae. These ants compete intensively with neighboring colonies of conspecifics and with three sympatric ant species for resources associated with the whistlingthorn acacias in which they all obligately nest. We used the genotypes of alate males at ten microsatellite loci to reconstruct queen genotypes and found that C. mimosae colonies are frequently secondarily polygynous, in that they include multiple closely related (and sometimes fullsib)...

Li, Nan; Lewis, Joel Brewster
We study a family of discrete dynamical processes introduced by Novikoff, Kleinberg, and Strogatz that we call flashcard games. We prove a number of results on the evolution of these games, and in particular, we settle a conjecture of NKS on the frequency with which a given card appears. We introduce a number of generalizations and variations that we believe are of interest, and we provide a large number of open questions and problems.

Abughazalah, Nabilah; Etingof, Pavel I.
We show that every semigroup which is a finite disjoint union of copies of the free monogenic semigroup (natural numbers under addition) has linear growth. This implies that the corresponding semigroup algebra is a PI algebra.

Kasuya, Junichi; Pavesi, Andrea; Liebsch, Gregor; Ochs, Christopher J.
A new imaging system allows visualizing oxygen distributions in 2D. Combining sensor foils with microfluidic devices enables online monitoring of cellular oxygen consumption in whole chip areas. Furthermore, suitable device materials depending on application and cell line can be determined. Numerically simulated oxygen consumption of rat lung microvascular endothelial cells and rat hepatocytes was experimentally validated.

Rührmair, Ulrich; van Dijk, Marten
In recent years, PUFbased schemes have been suggested not only for the basic tasks of tampersensitive key storage or the identification of hardware systems, but also for more complex protocols like oblivious transfer (OT) or bit commitment (BC), both of which possess broad and diverse applications. In this paper, we continue this line of research. We first present an attack on two recent OT and BC protocols which have been introduced by Brzuska et al. (CRYPTO, LNCS 6841, pp 51–70, Springer 2011). The attack quadratically reduces the number of CRPs which malicious players must read out to cheat, and fully...

BenMansour, Rached; Sahin, Ahmet Z.
Fluid flow characteristics and entropy generation in a circular diffuser/nozzle element are studied numerically. The flow is assumed to be isothermal, laminar and incompressible with constant thermophysical properties. The velocity field, mass flow rate, and entropy generation are investigated for several half angles in combination with several values of pressure drops. The effect of diffuser half angle on the entropy generation is investigated and discussed. Furthermore, the effect of the half angle of diffuser on the diffuser efficiency and the effect on the rectification efficiency are explained. It is shown that there is an optimum operation half angle for which...

Doherty, P.; Ariyibi, E. A.; Joshua, E. O.; Coster, Anthea J.
IleIfe lies on the equatorial anomaly region where the ionospheric current is greatly influenced by the existence of the equatorial electrojet. The dual frequency SCINDA NovAtel GSV 4004B GPS receiver recently installed at IleIfe [on geographical latitude 7°33′N and longitude 4°33′E and geomagnetic dipole (coordinate) of latitude 9.84°N and longitude 77.25°E] is currently operational and recording data from the available global positioning system satellites. The receiver provides the data on total electron content (TEC) and the scintillation index (S[subscript 4]). This paper presents the first sets of results from this station. Data records for the month of February 2010 were...

Ulm, FranzJosef
This paper summarizes recent developments in the field of nanoindentation analysis of highly heterogeneous composites. The fundamental idea of the proposed approach is that it is possible to assess nanostructure from the implementation of micromechanicsbased scaling relations for a large array of nanoindentation tests on heterogeneous materials. We illustrate this approach through the application to calciumsilicatehydrate (CSH), the binding phase of all cementbased materials. For this important class of materials, we show that CSH exists in at least three structurally distinct but compositionally similar forms: low density, high density and ultrahigh density. These three forms differ merely in the packing...

Voronin, Sergey; Mikesell, Dylan; Nolet, Guust
We introduce and compare new compression approaches to obtain regularized solutions of large linear systems which are commonly encountered in large scale inverse problems. We first describe how to approximate matrix vector operations with a large matrix through a sparser matrix with fewer nonzero elements, by borrowing from ideas used in wavelet image compression. Next, we describe and compare approaches based on the use of the low rank singular value decomposition (SVD), which can result in further size reductions. We describe how to obtain the approximate low rank SVD of the original matrix using the sparser wavelet compressed matrix. Some...

Belenky, Alexander S.
The problem of developing a decision support system for estimating a) the scale of incorporating available renewable sources of energy (such as solar and wind energy) in a part of a country’s electrical grid (called a regional electrical grid further in this paper), and b) the scale of storing electricity in this (regional) electrical grid to make these renewable sources of electric power competitive with traditional power generators (such as fossilfuel and nuclear ones) and to reduce the cost of acquiring electricity from all the electric power generating facilities in the grid is considered. In the framework of this system,...

Belenky, Alexander S.
A game with a finite (more than three) number of players on a polyhedron of connected player strategies is studied. This game describes the interaction among (a) the base load power plant (the generator), (b) all the large customers of a regional electrical grid that receive electric energy from the generator, as well as from the available renewable sources of energy, both directly and via electricity storing facilities, and (c) the transmission company. An auxiliary threeperson game on polyhedra of disjoint player strategies that is associated with the initial game is also considered. It is shown that an equilibrium point...

Weiner, Adam Michael; McGovern, Ronan Killian; Lienhard, John H.
We develop a framework for choosing the optimal load resistance, feed velocity and residence time for a reverse electrodialysis stack based on minimizing the levelized cost of electricity. The optimal load resistance maximizes the gross stack power density and results from a tradeoff between stack voltage and stack current. The primary tradeoff governing the optimal feed velocity is between stack pumping power losses, which reduce the net power density and concentration polarization losses, which reduce the gross stack power density. Lastly, the primary tradeoff governing the optimal residence time is between the capital costs of the stack and pretreatment system....

Rodriguez Nieva, Joaquin Francisco; Dresselhaus, Mildred; Levitov, Leonid
We predict that vertical transport in heterostructures formed by twisted graphene layers can exhibit a unique bistability mechanism. Intrinsically bistable IV characteristics arise from resonant tunneling and interlayer charge coupling, enabling multiple stable states in the sequential tunneling regime. We consider a simple trilayer architecture, with the outer layers acting as the source and drain and the middle layer floating. Under bias, the middle layer can be either resonant or nonresonant with the source and drain layers. The bistability is controlled by geometric device parameters easily tunable in experiments. The nanoscale architecture can enable uniquely fast switching times.

Trajkovski, Mirko; Lodish, Harvey F.
Brown adipose tissue (BAT) is specialized for heat generation and energy expenditure as a defense against cold and obesity; in both humans and mice increased amounts of BAT are associated with a lean phenotype and resistance to development of the metabolic syndrome and its complications. Here we summarize recent research showing that several BATexpressed microRNAs (miRNAs) play important roles in regulating differentiation and metabolism of brown and beige adipocytes; we discuss the key mRNA targets downregulated by these miRNAs and show how these miRNAs affect directly or indirectly transcription factors important for BAT development. We suggest that these miRNAs could...

Speed, Alexander W. H.; Mann, Tyler J.; O’Brien, Robert V.; Schrock, Richard Royce; Hoveyda, Amir H.
A convergent diastereo and enantioselective total synthesis of anticancer and antifungal macrocyclic natural product disorazole C1 is reported. The central feature of the successful route is the application of catalytic Zselective crossmetathesis (CM). Specifically, we illustrate that catalystcontrolled stereoselective CM can be performed to afford structurally complex Zalkenyl–B(pin) as well as Zalkenyl iodide compounds reliably, efficiently, and with high selectivity (pin = pinacolato). The resulting intermediates are then joined in a singlestep operation through catalytic inter and intramolecular crosscoupling to furnish the desired 30membered ring macrocycle containing the critical (Z,Z,E)triene moieties.

Riddell, Imogen Anne; Johnstone, Timothy; Park, Ga Young; Lippard, Stephen J.
The monofunctional platinum anticancer agent phenanthriplatin generates covalent adducts with the purine bases guanine and adenine. Preferential nucleotide binding was investigated by using a polymerase stop assay and linear DNA amplification with a 163base pair DNA double helix. Similarly to cisplatin, phenanthriplatin forms the majority of adducts at guanosine residues, but significant differences in both the number and position of platination sites emerge when comparing results for the two complexes. Notably, the monofunctional complex generates a greater number of polymerasehalting lesions at adenosine residues than does cisplatin. Studies with 9methyladenine reveal that, under abiological conditions, phenanthriplatin binds to the N1...