Flexible Fiber-based Micro and Nanofluidics for Probing Liquids

A fluidic probe comprising a plurality of oriented fibers with individual fibers having nano-pores in the fiber bodies, the oriented fibers being twisted together, wherein the twisted oriented fibers form micro-pores between the individual fibers, is disclosed. The fluidic probe exhibits excellent flexibility, deployability and absorptive capacity. The enhanced absorptive capacity is due to the fluid absorption via capillary action of the nano-pores and fluid transport via the micro-pores. The probes can also be formed so as to be remotely controlled by electromagnetic fields and thus be used in a hands-free fashion. With these probes, the paradigm of a stationary microfluidic platform can be shifted to include flexible structures that can include multiple microfluidic sensors in a single fibrous probe

Simple and complex modelling of seat-type abutment-backfill systems

The response of the seat-type abutment-backfill system under a dynamic excitation and its contribution to the structural system of the entire bridge is usually ignored in practice in Europe, since the designers prefer providing joint gap sizes larger than the required for the design earthquake. In the high seismic hazard areas of the US, various versions of Caltrans Guidelines prescribe a relatively simple way to account for the abutment - backfill interaction. However, the design of Caltrans abutments is based on the 'fully sacrificial' approach, wherein the backwall 'shears off' at an early stage, while in other countries the detailing of the deck-abutment interface is such that a plastic hinge forms at the base of the backwall which is detailed for ductile behaviour. In all cases, if assessment of the bridge safety beyond the design earthquake is sought (e.g. in fragility analysis), it is essential to properly account for the response of the bridge when the end joint is closed. This paper focuses on seat-type abutments with backwall hinging. In a practical context, a 'simple' model in this case consists of a spring-gap element that models the entire abutment-backfill system, while a 'complex' model includes explicit modelling of the abutment using beam-column elements, and of the backfill behind it using one or multiple soil springs. For dynamic response-history analysis, dashpots are also needed for modelling radiation damping. The issues of the number and the arrangement of the spring-dashpot systems and their nonlinear constitutive laws are addressed herein and several configurations are studied. SAP 2000 is used for analysing a typical overpass bridge with seat-type abutments and joints in both the longitudinal and transverse directions, for a number of spectrum compatible records. A series of pushover analyses of the 'complex' model are also carried out; their output can be used to define the (single) spring properties of the simple model. Interesting conclusions are drawn, both with regard to the spring configuration and to the difficulties in combining the various nonlinear elements in SAP 2000

Effect of abutment-backfill limit state definition on the assessment of seismic performance

Over the last decades, several performance-based design and assessment procedures for bridges under earthquake loading have been put forward. For assessing seismic performance, an appropriate definition of limit states is necessary. For bridges with seat-type abutments, the importance of limit states related to damage in the abutment-backfill system is often overlooked, partly due to the use of joint gaps that substantially exceed the expected design seismic displacement of the deck; nevertheless, gap closure may still occur for earthquakes stronger than the design one, with beneficial or detrimental impact on the bridge behaviour. Here, the important limit states of ‘operationality’ and ‘collapse prevention’ are defined using different criteria for the various bridge components, including the abutment-backfill system; for the latter, displacement-based criteria that express damage in the backfill and the shear keys and their effect on the entire bridge were used for the longitudinal and the transverse direction, respectively. The effect of the selected criteria which are subject to uncertainty was studied for a typical concrete overpass. Nonlinear dynamic analyses were conducted for different levels of seismic action and the results were used to evaluate the performance of the bridge in either direction using a range of values for the criteria related to the abutment-backfill system. It was found that the abutment-backfill based limit states could be critical for certain levels of ground motion with regard to both the ‘operationality’ and the ‘collapse prevention’ of the bridge

The Role of Wind Waves in Dynamics of the Air-Sea Interface

Wind waves are considered as an intermediate small-scale dynamic process at the air-sea interface,which modulates radically middle-scale dynamic processes of the boundary layers in water and air. It is shown that with the aim of a quantitative description of the impact said, one can use the numerical wind wave models which are added with the blocks of the dynamic atmosphere boundary layer (DABL) and the dynamic water upper layer (DWUL). A mathematical formalization for the problem of energy and momentum transfer from the wind to the upper ocean is given on the basis of the well known mathematical representations for mechanisms of a wind wave spectrum evolution. The problem is solved quantitatively by means of introducing special system parameters: the relative rate of the wave energy input, IRE, and the relative rate of the wave energy dissipation, DRE. For two simple wave-origin situations, the certain estimations for values of IRE and DRE are found, and the examples of calculating an impact of a wind sea on the characteristics of both the boundary layer of atmosphere and the water upper layer are given. The results obtained permit to state that the models of wind waves of the new (fifth) generation, which are added with the blocks of the DABL and the DWUL, could be an essential chain of the general model describing the ocean-atmosphere circulation.Comment: 11 pages, 4 figures, 1 tabl

Emerging IT risks: insights from German banking

How do German banks manage the emerging risks stemming from IT innovations such as cyber risk? With a focus on process, roles and responsibilities, field data from ten banks participating in the 2014 ECB stress test were collected by interviewing IT managers, risk managers and external experts. Current procedures for handling emerging risks in German banks were identified from the interviews and analysed, guided by the extant literature. A clear gap was found between enterprise risk management (ERM) as a general approach to risks threatening firms’ objectives and ERM’s neglect of emerging risks, such as those associated with IT innovations. The findings suggest that ERM should be extended towards the collection and sharing of knowledge to allow for an initial understanding and description of emerging risks, as opposed to the traditional ERM approach involving estimates of impact and probability. For example, as cyber risks emerge from an IT innovation, the focus may need to switch towards reducing uncertainty through knowledge acquisition. Since individual managers seldom possess all relevant knowledge of an IT innovation, various stakeholders may need to be involved to exploit their expertise

Transverse momentum and centrality dependence of dihadron correlations in Au+Au collisions at sqrt(s_NN)=200 GeV: Jet-quenching and the response of partonic matter

Azimuthal angle \Delta\phi correlations are presented for charged hadrons from dijets for 0.4 < p_T < 10 GeV/c in Au+Au collisions at sqrt(s_NN) = 200 GeV. With increasing p_T, the away-side distribution evolves from a broad to a concave shape, then to a convex shape. Comparisons to p+p data suggest that the away-side can be divided into a partially suppressed "head" region centered at Delta\phi ~ \pi, and an enhanced "shoulder" region centered at Delta\phi ~ \pi +/- 1.1. The p_T spectrum for the "head" region softens toward central collisions, consistent with the onset of jet quenching. The spectral slope for the "shoulder" region is independent of centrality and trigger p_T, which offers constraints on energy transport mechanisms and suggests that the "shoulder" region contains the medium response to energetic jets.Comment: 420 authors from 58 institutions, 6 pages, 4 figures. Submitted to Physical Review Letters. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

Cold Nuclear Matter Effects on J/Psi as Constrained by Deuteron-Gold Measurements at sqrt(s_NN) = 200 GeV

We present a new analysis of J/psi production yields in deuteron-gold collisions at sqrt(s_NN) = 200 GeV using data taken by the PHENIX experiment in 2003 and previously published in [S.S. Adler et al., Phys. Rev. Lett 96, 012304 (2006)]. The high statistics proton-proton J/psi data taken in 2005 is used to improve the baseline measurement and thus construct updated cold nuclear matter modification factors R_dAu. A suppression of J/psi in cold nuclear matter is observed as one goes forward in rapidity (in the deuteron-going direction), corresponding to a region more sensitive to initial state low-x gluons in the gold nucleus. The measured nuclear modification factors are compared to theoretical calculations of nuclear shadowing to which a J/psi (or precursor) break-up cross-section is added. Breakup cross sections of sigma_breakup = 2.8^[+1.7_-1.4] (2.2^[+1.6_-1.5]) mb are obtained by fitting these calculations to the data using two different models of nuclear shadowing. These breakup cross section values are consistent within large uncertainties with the 4.2 +/- 0.5 mb determined at lower collision energies. Projecting this range of cold nuclear matter effects to copper-copper and gold-gold collisions reveals that the current constraints are not sufficient to firmly quantify the additional hot nuclear matter effect.Comment: 453 authors from 59 institutions, 15 pages, 13 figures, 5 tables. Submitted to Physical Review C. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm