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Full-Text Articles in Engineering
An Archimedes' Screw For Light, Emanuele Galiffi, Paloma A. Huidobro, J. B. Pendry
An Archimedes' Screw For Light, Emanuele Galiffi, Paloma A. Huidobro, J. B. Pendry
Advanced Science Research Center
An Archimedes’ Screw captures water, feeding energy into it by lifting it to a higher level. We introduce the first instance of an optical Archimedes’ Screw, and demonstrate how this system is capable of capturing light, dragging it and amplifying it. We unveil new exact analytic solutions to Maxwell’s Equations for a wide family of chiral space-time media, and show their potential to achieve chirally selective amplification within widely tunable parity-time-broken phases. Our work, which may be readily implemented via pump-probe experiments with circularly polarized beams, opens a new direction in the physics of time-varying media by merging the rising …
Imaging Thermal Conductivity With Nanoscale Resolution Using A Scanning Spin Probe, Abdelghani Laraoui, Halley Aycock-Rizzo, Yang Gao, Xi Lu, Elisa Riedo, Carlos A. Meriles
Imaging Thermal Conductivity With Nanoscale Resolution Using A Scanning Spin Probe, Abdelghani Laraoui, Halley Aycock-Rizzo, Yang Gao, Xi Lu, Elisa Riedo, Carlos A. Meriles
Advanced Science Research Center
The ability to probe nanoscale heat flow in a material is often limited by lack of spatial resolution. Here, we use a diamond-nanocrystal-hosted nitrogen-vacancy centre attached to the apex of a silicon thermal tip as a local temperature sensor. We apply an electrical current to heat up the tip and rely on the nitrogen vacancy to monitor the thermal changes the tip experiences as it is brought into contact with surfaces of varying thermal conductivity. By combining atomic force and confocal microscopy, we image phantom microstructures with nanoscale resolution, and attain excellent agreement between the thermal conductivity and topographic maps. …
Impair-Then-Repair: A Brief History & Global-Scale Hypothesis Regarding Human-Water Interactions In The Anthropocene, Charles J. Vörösmarty, Michel Meybeck, Christopher L. Pastore
Impair-Then-Repair: A Brief History & Global-Scale Hypothesis Regarding Human-Water Interactions In The Anthropocene, Charles J. Vörösmarty, Michel Meybeck, Christopher L. Pastore
Advanced Science Research Center
Water is an essential building block of the Earth system and a nonsubstitutable resource upon which humankind must depend. But a growing body of evidence shows that freshwater faces a pandemic array of challenges. Today we can observe a globally significant but collectively unorganized approach to addressing them. Under modern water management schemes, impairment accumulates with increasing wealth but is then remedied by costly, after-the-fact technological investments. This strategy of treating symptoms rather than underlying causes is practiced widely across rich countries but leaves poor nations and many of the world's freshwater life-forms at risk. The seeds of this modern …
Historical Legacies, Information And Contemporary Water Science And Management, Daniel J. Bain, Jennifer A. S. Arrigo, Mark B. Green, Brian A. Pellerin, Charles J. Vörösmarty
Historical Legacies, Information And Contemporary Water Science And Management, Daniel J. Bain, Jennifer A. S. Arrigo, Mark B. Green, Brian A. Pellerin, Charles J. Vörösmarty
Advanced Science Research Center
Hydrologic science has largely built its understanding of the hydrologic cycle using contemporary data sources (i.e., last 100 years). However, as we try to meet water demand over the next 100 years at scales from local to global, we need to expand our scope and embrace other data that address human activities and the alteration of hydrologic systems. For example, the accumulation of human impacts on water systems requires exploration of incompletely documented eras. When examining these historical periods, basic questions relevant to modern systems arise: (1) How is better information incorporated into water management strategies? (2) Does any point …
Influence Of Arctic Wetlands On Arctic Atmospheric Circulation, William J. Gutowski Jr., Helen Wei, Charles J. Vörösmarty, Balazs M. Fekete
Influence Of Arctic Wetlands On Arctic Atmospheric Circulation, William J. Gutowski Jr., Helen Wei, Charles J. Vörösmarty, Balazs M. Fekete
Advanced Science Research Center
The Arctic’s land surface has large areas of wetlands that exchange moisture, energy, and momentum with the atmosphere. The authors use a mesoscale, pan-Arctic model simulating the summer of 1986 to examine links between the wetlands and arctic atmospheric dynamics and water cycling. Simulations with and without wetlands are compared to simulations using perturbed initial and lateral boundary conditions to delineate when and where the wetlands influence rises above nonlinear internal variability. The perturbation runs expose the temporal variability of the circulation’s sensitivity to changes in lower boundary conditions. For the wetlands cases examined here, the period of the most …
Uncertainties In Precipitation And Their Impacts On Runoff Estimates, Balazs M. Fekete, Charles J. Vörösmarty, John O. Roads, Cort J. Willmott
Uncertainties In Precipitation And Their Impacts On Runoff Estimates, Balazs M. Fekete, Charles J. Vörösmarty, John O. Roads, Cort J. Willmott
Advanced Science Research Center
Water balance calculations are becoming increasingly important for earth-system studies. Precipitation is one of the most critical input variables for such calculations because it is the immediate source of water for the land surface hydrological budget. Numerous precipitation datasets have been developed in the last two decades, but these datasets often show marked differences in their spatial and temporal distribution of this key hydrological variable. This paper compares six monthly precipitation datasets—Climate Research Unit of University of East Anglia (CRU), Willmott–Matsuura (WM), Global Precipitation Climate Center (GPCC), Global Precipitation Climatology Project (GPCP), Tropical Rainfall Measuring Mission (TRMM), and NCEP–Department of …
Calibration And Validation Of A Regional Climate Model For Pan-Arctic Hydrologic Simulation, Helin Wei, William J. Gutowski Jr., Charles J. Vörösmarty, Balazs M. Fekete
Calibration And Validation Of A Regional Climate Model For Pan-Arctic Hydrologic Simulation, Helin Wei, William J. Gutowski Jr., Charles J. Vörösmarty, Balazs M. Fekete
Advanced Science Research Center
A number of polar datasets have recently been released involving in situ measurements, satellite retrievals, and reanalysis output that provide new opportunities to evaluate regional climate in the Arctic. These data have been used to assess a 1-yr pan-Arctic simulation (October 1985–September 1986) performed by a version of the fifth-generation Pennsylvania State University–National Center for Atmospheric Research (PSU–NCAR) Mesoscale Model (MM5) that incorporated the NCAR land surface model (LSM) and a simple thermodynamic sea ice model to investigate interactions between the land surface and atmosphere. The model’s standard cloud scheme using relative humidity was replaced by one using simulated cloud …