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Capital Markets Technology Manager (Multiple Positions) | PricewaterhouseCoopers Advisory Services LLC

SPS Jobs - 28 July 2016
US - NY - New York, Capital Markets Technology Manager (Multiple Positions), PricewaterhouseCoopers Advisory Services LLC, New York, NY. Provide management, technology and risk consulting services to help clients respon

Salesforce.com Senior Associate (Multiple Positions) | PricewaterhouseCoopers Advisory Services LLC

SPS Jobs - 28 July 2016
US - IL - Chicago, Salesforce.com Senior Associate (Multiple Positions), PricewaterhouseCoopers Advisory Services LLC, Chicago, IL. Assist clients with improving business performance, responding quickly and effectively

Mid-Level Mechanical / Energy Engineer | Amec Foster Wheeler Environment & Infrastructure, Inc.

SPS Jobs - 28 July 2016
US - FL - Orlando, Skills / Qualifications B.S. or M.S. in Mechanical Engineering 2-5 years of related experience Mechanical EIT or recently acquired P.E. Valid driver's license Flexibility to work and travel ou

Life Safety Service Manager | SIGNET Electronic Systems

SPS Jobs - 28 July 2016
US - MA - Norwell, We’re looking for someone who is passionate about the Life Safety Industry and providing outstanding service that keeps our clients safe and secure.  We have a dynamic team of technicians

Associate Laboratory Director for Energy Sciences | Energy Sciences

SPS Jobs - 28 July 2016
US - CA, Associate Laboratory Director for Energy Sciences - 82697 Organization: LD-Laboratory Directorate   As the Associate Laboratory Director for Energy Sciences, you will  have Laboratory wi

Greenland glacier melt documented through archival photos and records

Nature: Archival photographs, sketches, and temperature measurements are being used by researchers to better understand the effects of climate change on Greenland’s ice sheet and glaciers. Conducting historical glacier research, Anders Bjørk at the Natural History Museum of Denmark in Copenhagen is a real-life Indiana Jones. Not only does he sift through old photographs, maps, and other documents in castles and museums, but he has also embarked on numerous epic sea voyages. He and his colleagues are now comparing the historic weather data with modern satellite data to see how Greenland's glaciers have changed over the past 80 years. Among what they have learned so far is that glaciers are more sensitive to periods of warming and cooling than previously thought and that not all glaciers respond to warming in the same way.

Pacific tectonic plate may have grown from a single point

Science News: The largest of Earth’s tectonic plates may actually have started out as the smallest, according to a new study in Science Advances. Unlike the other modern plates, which formed when ancient plates split into two, the Pacific Plate may have grown from a single point located at the junction of three older plates. Lydian Boschman of Utrecht University in the Netherlands and her colleagues say that at some time one of the three plates overlapped another one, causing a piece to break off and get pushed under the rest. That event created the three-way junction, around which the plates proceeded to glide past each other in a pinwheel motion rather than pull apart. As the gap widened, molten rock flowed up into the void, and the plate formed and grew.

A path to better lithium-ion battery performance

Engineering electrode structures straightens the tortuous route that ions must travel.

NOAA takes first step toward developing new global weather model

Washington Post: The US National Oceanic and Atmospheric Administration has announced that it is updating its Global Forecast System (GFS) weather model. The new GFS will feature the FV3 dynamic core created by NOAA’s Geophysical Fluid Dynamics Laboratory. The FV3 was chosen over other candidates primarily because of its computational efficiency, which is essential for running all the necessary weather and climate models. NOAA says the goals are to improve forecast accuracy beyond 8–10 days, to better model forecasts of hurricanes and their intensity, and to extend weather forecasts to 14 days in advance and extreme event forecasts to 3–4 weeks in advance. Now that a core has been selected, the next steps are to test and improve the weather-predicting algorithms and develop a method to assimilate all the data from satellites, weather balloons, and ground-based observations.

A cavitation transition in the energy landscape of simple cohesive liquids and glasses

In particle systems with cohesive interactions, the pressure-density relationship of the mechanically stable inherent structures sampled along a liquid isotherm (i.e., the equation of state of an energy landscape) will display a minimum at the Sastry density ρS. The tensile limit at ρS is due to cavitation that occurs upon energy minimization, and previous characterizations of this behavior suggested that ρS is a spinodal-like limit that separates all homogeneous and fractured inherent structures. Here, we revisit the phenomenology of Sastry behavior and find that it is subject to considerable finite-size effects, and the development of the inherent structure equation of state with system size is consistent with the finite-size rounding of an athermal phase transition. What appears to be a continuous spinodal-like point at finite system sizes becomes discontinuous in the thermodynamic limit, indicating behavior akin to a phase transition. We also study cavitation in glassy packings subjected to athermal expansion. Many individual expansion trajectories averaged together produce a smooth equation of state, which we find also exhibits features of finite-size rounding, and the examples studied in this work give rise to a larger limiting tension than for the corresponding landscape equation of state.

Conformational landscape of an amyloid intra-cellular domain and Landau-Ginzburg-Wilson paradigm in protein dynamics

The Landau-Ginzburg-Wilson paradigm is proposed as a framework, to investigate the conformational landscape of intrinsically unstructured proteins. A universal Cα-trace Landau free energy is deduced from general symmetry considerations, with the ensuing all-atom structure modeled using publicly available reconstruction programs Pulchra and Scwrl. As an example, the conformational stability of an amyloid precursor protein intra-cellular domain (AICD) is inspected; the reference conformation is the crystallographic structure with code 3DXC in Protein Data Bank (PDB) that describes a heterodimer of AICD and a nuclear multi-domain adaptor protein Fe65. Those conformations of AICD that correspond to local or near-local minima of the Landau free energy are identified. For this, the response of the original 3DXC conformation to variations in the ambient temperature is investigated, using the Glauber algorithm. The conclusion is that in isolation the AICD conformation in 3DXC must be unstable. A family of degenerate conformations that minimise the Landau free energy is identified, and it is proposed that the native state of an isolated AICD is a superposition of these conformations. The results are fully in line with the presumed intrinsically unstructured character of isolated AICD and should provide a basis for a systematic analysis of AICD structure in future NMR experiments.

Colloids exposed to random potential energy landscapes: From particle number density to particle-potential and particle-particle interactions

Colloidal particles were exposed to a random potential energy landscape that has been created optically via a speckle pattern. The mean particle density as well as the potential roughness, i.e., the disorder strength, were varied. The local probability density of the particles as well as its main characteristics were determined. For the first time, the disorder-averaged pair density correlation function g (1)(r) and an analogue of the Edwards-Anderson order parameter g (2)(r), which quantifies the correlation of the mean local density among disorder realisations, were measured experimentally and shown to be consistent with replica liquid state theory results.

Induced liquid-crystalline ordering in solutions of stiff and flexible amphiphilic macromolecules: Effect of mixture composition

Impact of mixture composition on self-organization in concentrated solutions of stiff helical and flexible macromolecules was studied by means of molecular dynamics simulation. The macromolecules were composed of identical amphiphilic monomer units but a fraction f of macromolecules had stiff helical backbones and the remaining chains were flexible. In poor solvents the compacted flexible macromolecules coexist with bundles or filament clusters from few intertwined stiff helical macromolecules. The increase of relative content f of helical macromolecules leads to increase of the length of helical clusters, to alignment of clusters with each other, and then to liquid-crystalline-like ordering along a single direction. The formation of filament clusters causes segregation of helical and flexible macromolecules and the alignment of the filaments induces effective liquid-like ordering of flexible macromolecules. A visual analysis and calculation of order parameter relaying the anisotropy of diffraction allow concluding that transition from disordered to liquid-crystalline state proceeds sharply at relatively low content of stiff components.

Impact of annealing on electrical properties of Cu2ZnSnSe4 absorber layers

Reported growth processes for kesterite absorber layers generally rely on a sequential process including a final high temperature annealing step. However, the impact and details for this annealing process vary among literature reports and little is known on its impact on electrical properties of the absorber. We used kesterite absorber layers prepared by a high temperature co-evaporation process to explicitly study the impact of two different annealing processes. From electrical characterization it is found that the annealing process incorporates a detrimental deep defect distribution. On the other hand, the doping density could be reduced leading to a better collection and a higher short circuit current density. The activation energy of the doping acceptor was studied with admittance spectroscopy and showed Meyer–Neldel behaviour. This indicates that the entropy significantly contributes to the activation energy.

In a search for a shape maximizing packing fraction for two-dimensional random sequential adsorption

Random sequential adsorption of various two dimensional objects is studied in order to find a shape which maximizes the saturated packing fraction. This investigation was begun in our previous paper [Cieśla et al., Phys. Chem. Chem. Phys. 17, 24376 (2015)], where the densest packing was studied for smoothed dimers. Here this shape is compared with the smoothed n-mers, spherocylinders, and ellipses. It is found that the highest packing fraction out of the studied shapes is 0.584 05 ± 0.0001 and is obtained for ellipses having long-to-short axis ratio of 1.85 ± 0.07.

Exploration of CdTe quantum dots as mesoscale pressure sensors via time-resolved shock-compression photoluminescent emission spectroscopy

The nanometer size of CdTe quantum dots (QDs) and their unique optical properties, including size-tunable narrow photoluminescent emission, broad absorption, fast photoluminescence decay, and negligible light scattering, are ideal features for spectrally tagging the shock response of localized regions in highly heterogeneous materials such as particulate media. In this work, the time-resolved laser-excited photoluminescence response of QDs to shock-compression was investigated to explore their utilization as mesoscale sensors for pressure measurements and in situ diagnostics during shock loading experiments. Laser-driven shock-compression experiments with steady-state shock pressures ranging from 2.0 to 13 GPa were performed on nanocomposite films of CdTe QDs dispersed in a soft polyvinyl alcohol polymer matrix and in a hard inorganic sodium silicate glass matrix. Time-resolved photoluminescent emission spectroscopy was used to correlate photoluminescence changes with the history of shock pressure and the dynamics of the matrix material surrounding the QDs. The results revealed pressure-induced blueshifts in emitted wavelength, decreases in photoluminescent emission intensity, reductions in peak width, and matrix-dependent response times. Data obtained for these QD response characteristics serve as indicators for their use as possible time-resolved diagnostics of the dynamic shock-compression response of matrix materials in which such QDs are embedded as in situ sensors.

Phononic thermal resistance due to a finite periodic array of nano-scatterers

The wave property of phonons is employed to explore the thermal transport across a finite periodic array of nano-scatterers such as circular and triangular holes. As thermal phonons are generated in all directions, we study their transmission through a single array for both normal and oblique incidences, using a linear dispersionless time-dependent acoustic frame in a two-dimensional system. Roughness effects can be directly considered within the computations without relying on approximate analytical formulae. Analysis by spatio-temporal Fourier transform allows us to observe the diffraction effects and the conversion of polarization. Frequency-dependent energy transmission coefficients are computed for symmetric and asymmetric objects that are both subject to reciprocity. We demonstrate that the phononic array acts as an efficient thermal barrier by applying the theory of thermal boundary (Kapitza) resistances to arrays of smooth scattering holes in silicon for an exemplifying periodicity of 10 nm in the 5–100 K temperature range. It is observed that the associated thermal conductance has the same temperature dependence as that without phononic filtering.


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