Aging aerosol in a well-mixed continuous-flow tank reactor: an introduction of the activation time distribution

Two approaches are commonly used to simulate atmospheric aging processes in the laboratory. The experiments are either performed in large aerosol chambers (several m3) in order to achieve extended observation times or in small chambers (&lt;&thinsp;1&thinsp;m3), compensating for the short observation times by elevated reactant concentrations. We present an experimental approach that enables long observation times at atmospherically relevant reactant concentrations in small chamber volumes by operating the aerosol chamber as a continuous-flow stirred tank reactor (CSTR). We developed a mathematical framework that allows the retrieval of data beyond calculating mean values, such as O3 exposure or equivalent atmospheric aging time, using the new metric, activation time (tact). This concept was developed and successfully tested to characterize the change in cloud condensation nuclei (CCN) activity of soot particles due to heterogeneous ozone oxidation. We found very good agreement between the experimental results and the theoretical predictions. This experimental approach and data analysis concept can be applied for the investigation of any transition in aerosol particles properties that can be considered a binary system. Furthermore, we show how tact can be applied to the analysis of data originating from other reactor types such as oxidation flow reactors (OFRs), which are widely used in atmospheric sciences. The new tact concept significantly supports the understanding of data acquired in OFRs, especially those from deviating experimental results in intercomparison campaigns.</p

Automatic Creation of High-Bandwidth Memory Architectures from Domain-Specific Languages: The Case of Computational Fluid Dynamics

Numerical simulations can help solve complex problems. Most of these algorithms are massively parallel and thus good candidates for FPGA acceleration thanks to spatial parallelism. Modern FPGA devices can leverage high-bandwidth memory technologies, but when applications are memory-bound designers must craft advanced communication and memory architectures for efficient data movement and on-chip storage. This development process requires hardware design skills that are uncommon in domain-specific experts. In this paper, we propose an automated tool flow from a domain-specific language (DSL) for tensor expressions to generate massively-parallel accelerators on HBM-equipped FPGAs. Designers can use this flow to integrate and evaluate various compiler or hardware optimizations. We use computational fluid dynamics (CFD) as a paradigmatic example. Our flow starts from the high-level specification of tensor operations and combines an MLIR-based compiler with an in-house hardware generation flow to generate systems with parallel accelerators and a specialized memory architecture that moves data efficiently, aiming at fully exploiting the available CPU-FPGA bandwidth. We simulated applications with millions of elements, achieving up to 103 GFLOPS with one compute unit and custom precision when targeting a Xilinx Alveo U280. Our FPGA implementation is up to 25x more energy efficient than expert-crafted Intel CPU implementations

Motional Squashed States

We show that by using a feedback loop it is possible to reduce the fluctuations in one quadrature of the vibrational degree of freedom of a trapped ion below the quantum limit. The stationary state is not a proper squeezed state, but rather a ``squashed'' state, since the uncertainty in the orthogonal quadrature, which is larger than the standard quantum limit, is unaffected by the feedback action.Comment: 8 pages, 2 figures, to appear in the special Issue "Quantum Correlations and Fluctuations" of J. Opt.

Multiple micro-optical atom traps with a spherically aberrated laser beam

We report on the loading of atoms contained in a magneto-optic trap into multiple optical traps formed within the focused beam of a CO_{2} laser. We show that under certain circumstances it is possible to create a linear array of dipole traps with well separated maxima. This is achieved by focusing the laser beam through lenses uncorrected for spherical aberration. We demonstrate that the separation between the micro-traps can be varied, a property which may be useful in experiments which require the creation of entanglement between atoms in different micro-traps. We suggest other experiments where an array of these traps could be useful.Comment: 10 pages, 3 figure

All Optical Formation of an Atomic Bose-Einstein Condensate

We have created a Bose-Einstein condensate of 87Rb atoms directly in an optical trap. We employ a quasi-electrostatic dipole force trap formed by two crossed CO_2 laser beams. Loading directly from a sub-doppler laser-cooled cloud of atoms results in initial phase space densities of ~1/200. Evaporatively cooling through the BEC transition is achieved by lowering the power in the trapping beams over ~ 2 s. The resulting condensates are F=1 spinors with 3.5 x 10^4 atoms distributed between the m_F = (-1,0,1) states.Comment: 4 pages, 4 figures, to appear in Phys. Rev. Let

State of the Science of Scale-Up of Cancer Prevention and Early Detection interventions in Low- and Middle-income Countries: a Scoping Review

PURPOSE: Cancer deaths in low- and middle-income countries (LMICs) will nearly double by 2040. Available evidence-based interventions (EBIs) for cancer prevention and early detection can reduce cancer-related mortality, yet there is a lack of evidence on effectively scaling these EBIs in LMIC settings. METHODS: We conducted a scoping review to identify published literature from six databases between 2012 and 2022 that described efforts for scaling cancer prevention and early detection EBIs in LMICs. Included studies met one of two definitions of scale-up: (1) deliberate efforts to increase the impact of effective intervention to benefit more people or (2) an intervention shown to be efficacious on a small scale expanded under real-world conditions to reach a greater proportion of eligible population. Study characteristics, including EBIs, implementation strategies, and outcomes used, were summarized using frameworks from the field of implementation science. RESULTS: This search yielded 3,076 abstracts, with 24 studies eligible for inclusion. Included studies focused on a number of cancer sites including cervical (67%), breast (13%), breast and cervical (13%), liver (4%), and colon (4%). Commonly reported scale-up strategies included developing stakeholder inter-relationships, training and education, and changing infrastructure. Barriers to scale-up were reported at individual, health facility, and community levels. Few studies reported applying conceptual frameworks to guide strategy selection and evaluation. CONCLUSION: Although there were relatively few published reports, this scoping review offers insight into the approaches used by LMICs to scale up cancer EBIs, including common strategies and barriers. More importantly, it illustrates the urgent need to fill gaps in research to guide best practices for bringing the implementation of cancer EBIs to scale in LMICs

Quantum Logic Gates in Optical Lattices

We propose a new system for implementing quantum logic gates: neutral atoms trapped in a very far-off-resonance optical lattice. Pairs of atoms are made to occupy the same well by varying the polarization of the trapping lasers, and then a near-resonant electric dipole is induced by an auxiliary laser. A controlled-NOT can be implemented by conditioning the target atomic resonance on a resolvable level shift induced by the control atom. Atoms interact only during logical operations, thereby suppressing decoherence.Comment: Revised version, To appear in Phys. Rev. Lett. Three separate postscript figure

All-Optical Production of a Degenerate Fermi Gas

We achieve degeneracy in a mixture of the two lowest hyperfine states of $^6$Li by direct evaporation in a CO$_2$ laser trap, yielding the first all-optically produced degenerate Fermi gas. More than $10^5$ atoms are confined at temperatures below $4 \mu$K at full trap depth, where the Fermi temperature for each state is $8 \mu$K. This degenerate two-component mixture is ideal for exploring mechanisms of superconductivity ranging from Cooper pairing to Bose condensation of strongly bound pairs.Comment: 4 pgs RevTeX with 2 eps figs, to be published in Phys. Rev. Let

Press notice. EC agricultural price indices. Trends in EC agricultural price indices (output and input): 1st quarter 1985. 1985.3

The high precious metal loading and high overpotential of the oxygen evolution reaction (OER) prevents the widespread utilization of polymer electrolyte membrane (PEM) water electrolyzers. Herein we explore the OER activity and stability in acidic electrolyte of a combined IrO_<i>x</i>/RuO₂ system consisting of RuO₂ thin films with submonolayer (1, 2, and 4 Å) amounts of IrO_<i>x</i> deposited on top. Operando extended X-ray absorption fine structure (EXAFS) on the Ir L-3 edge revealed a rutile type IrO₂ structure with some Ir sites occupied by Ru, IrO_<i>x</i> being at the surface of the RuO₂ thin film. We monitor corrosion on IrO_<i>x</i>/RuO₂ thin films by combining electrochemical quartz crystal microbalance (EQCM) with inductively coupled mass spectrometry (ICP-MS). We elucidate the importance of submonolayer surface IrO_<i>x</i> in minimizing Ru dissolution. Our work shows that we can tune the surface properties of active OER catalysts, such as RuO₂, aiming to achieve higher electrocatalytic stability in PEM electrolyzers

Spinor Bosonic Atoms in Optical Lattices: Symmetry Breaking and Fractionalization

We study superfluid and Mott insulator phases of cold spin-1 Bose atoms with antiferromagnetic interactions in an optical lattice, including a usual polar condensate phase, a condensate of singlet pairs, a crystal spin nematic phase, and a spin singlet crystal phase. We suggest a possibility of exotic fractionalized phases of spinor BEC and discuss them in the language of topological defect condensation and $Z_2$ lattice gauge theory.Comment: 4 pages, 1 figure included; references adde