4,419 research outputs found
The Photochemical Decomposition of Nitric Oxide by Absorption in the (0,0) and (1,0) Ī³ Bands
The abnormally large pressure broadening observed in the Ī³ bands of NO was interpreted by Wulf as indicating a pressure-induced predissociation of the upper electronic state (A^2 Ī£)
Embedding human heuristics in machine-learning-enabled probe microscopy
Scanning probe microscopists generally do not rely on complete images to assess the quality of data acquired during a scan. Instead, assessments of the state of the tip apex, which not only determines the resolution in any scanning probe technique, but can also generate a wide array of frustrating artefacts, are carried out in real time on the basis of a few lines of an image (and, typically, their associated line profiles.) The very small number of machine learning approaches to probe microscopy published to date, however, involve classifications based on full images. Given that data acquisition is the most time-consuming task during routine tip conditioning, automated methods are thus currently extremely slow in comparison to the tried-and-trusted strategies and heuristics used routinely by probe microscopists. Here, we explore various strategies by which different STM image classes (arising from changes in the tip state) can be correctly identified from partial scans. By employing a secondary temporal network and a rolling window of a small group of individual scanlines, we find that tip assessment is possible with a small fraction of a complete image. We achieve this with little-to-no performance penaltyāor, indeed, markedly improved performance in some casesāand introduce a protocol to detect the state of the tip apex in real time
Measurement of Volumetric Flow
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135278/1/jum200625101305.pd
Direct Measurement of the System-Environment Coupling as a Tool For Understanding Decoherence and Dynamical Decoupling
Decoherence is a major obstacle to any practical implementation of quantum
information processing. One of the leading strategies to reduce decoherence is
dynamical decoupling --- the use of an external field to average out the effect
of the environment. The decoherence rate under any control field can be
calculated if the spectrum of the coupling to the environment is known. We
present a direct measurement of the bath coupling spectrum in an ensemble of
optically trapped ultracold atoms, by applying a spectrally narrow-band control
field. The measured spectrum follows a Lorentzian shape at low frequencies, but
exhibits non-monotonic features at higher frequencies due to the oscillatory
motion of the atoms in the trap. These features agree with our analytical
models and numerical Monte-Carlo simulations of the collisional bath. From the
inferred bath-coupling spectrum, we predict the performance of well-known
dynamical decoupling sequences: CPMG, UDD and CDD. We then apply these
sequences in experiment and compare the results to predictions, finding good
agreement in the weak-coupling limit. Thus, our work establishes experimentally
the validity of the overlap integral formalism, and is an important step
towards the implementation of an optimal dynamical decoupling sequence for a
given measured bath spectrum.Comment: 9 pages, 6 figure
A circadian based inflammatory response ā implications for respiratory disease and treatment
Circadian clocks regulate the daily timing of many of our physiological, metabolic and biochemical functions. The immune system also displays circadian oscillations in immune cell count, synthesis and cytokine release, clock gene expression in cells and organs of the immune system as well as clock-controlled genes that regulate immune function. Circadian disruption leads to dysregulation of immune responses and inflammation which can further disrupt circadian rhythms. The response of organisms to immune challenges, such as allergic reactions also vary depending on time of the day, which can lead to detrimental responses particularly during the rest and early active periods. This review evaluates what is currently known in terms of circadian biology of immune response and the cross-talk between circadian and immune system. We discuss the circadian pattern of three respiratory-related inflammatory diseases, chronic obstructive pulmonary disease, allergic rhinitis and asthma. Increasing our knowledge on circadian patterns of immune responses and developing chronotherapeutic studies in inflammatory diseases with strong circadian patterns will lead to preventive measures as well as improved therapies focussing on the circadian rhythms of symptoms and the daily variation of the patientsā responses to medication
Improving the Segmentation of Scanning Probe Microscope Images using Convolutional Neural Networks
A wide range of techniques can be considered for segmentation of images of
nanostructured surfaces. Manually segmenting these images is time-consuming and
results in a user-dependent segmentation bias, while there is currently no
consensus on the best automated segmentation methods for particular techniques,
image classes, and samples. Any image segmentation approach must minimise the
noise in the images to ensure accurate and meaningful statistical analysis can
be carried out. Here we develop protocols for the segmentation of images of 2D
assemblies of gold nanoparticles formed on silicon surfaces via deposition from
an organic solvent. The evaporation of the solvent drives far-from-equilibrium
self-organisation of the particles, producing a wide variety of nano- and
micro-structured patterns. We show that a segmentation strategy using the U-Net
convolutional neural network outperforms traditional automated approaches and
has particular potential in the processing of images of nanostructured systems.Comment: 21 pages, 10 figure
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The ocean's gravitational potential energy budget in a coupled climate model
This study examines, in a uniļ¬ed fashion, the budgets of ocean gravitational potential energy (GPE) and available gravitational potential energy (AGPE) in the control simulation of the coupled atmosphereāocean general
circulation model HadCM3. Only AGPE can be converted into kinetic energy by adiabatic processes. Diapycnal mixing supplies GPE, but not AGPE, whereas the reverse is true of the combined eļ¬ect of surface buoyancy forcing and convection. Mixing and buoyancy forcing, thus, play complementary roles in sustaining the large scale circulation. However, the largest globally integrated source of GPE is resolved advection (+0.57 TW) and the largest sink is through parameterized eddy transports (-0.82 TW). The eļ¬ect of these adiabatic processes on AGPE is identical to their eļ¬ect on GPE, except for
perturbations to both budgets due to numerical leakage exacerbated by non-linearities in the equation of state
Assessing the impact of drinking water and sanitation on diarrhoeal disease in low- and middle-income settings: Systematic review and meta-regression
Objective: To assess the impact of inadequate water and sanitation on diarrhoeal disease in low- and middle-income settings. Methods: The search strategy used Cochrane Library, MEDLINE & PubMed, Global Health, Embase and BIOSIS supplemented by screening of reference lists from previously published systematic reviews, to identify studies reporting on interventions examining the effect of drinking water and sanitation improvements in low- and middle-income settings published between 1970 and May 2013. Studies including randomised controlled trials, quasi-randomised trials with control group, observational studies using matching techniques and observational studies with a control group where the intervention was well defined were eligible. Risk of bias was assessed using a modified Ottawa-Newcastle scale. Study results were combined using meta-analysis and meta-regression to derive overall and intervention-specific risk estimates. Results: Of 6819 records identified for drinking water, 61 studies met the inclusion criteria, and of 12 515 records identified for sanitation, 11 studies were included. Overall, improvements in drinking water and sanitation were associated with decreased risks of diarrhoea. Specific improvements, such as the use of water filters, provision of high-quality piped water and sewer connections, were associated with greater reductions in diarrhoea compared with other interventions. Conclusions: The results show that inadequate water and sanitation are associated with considerable risks of diarrhoeal disease and that there are notable differences in illness reduction according to the type of improved water and sanitation implemented
Design of a Microsphere-Based High-Throughput Gene Expression Assay to Determine Estrogenic Potential
Recently gene expression studies have been multiplied at an accelerated rate by the use of high-density microarrays. By assaying thousands of transcripts at a time, microarrays have led to the discovery of dozens of genes involved in particular biochemical processes, for example, the response of a tissue/organ to a given chemical with therapeutic or toxic properties. The next step in these studies is to focus on the response of a subset of relevant genes to verify or refine potential therapeutic or toxic properties. We have developed a sensitive, high-throughput gene expression assay for this purpose. In this assay, based on the Luminex xMAP system, carefully selected oligonucleotides were covalently linked to fluorescently coded microspheres that are hybridized to biotinylated cRNA followed by amplification of the signal, which results in a rapid, sensitive, multiplexed assay platform. Using this system, we have developed an RNA expression profiling assay specific for 17 estrogen-responsive transcripts and three controls. This assay can evaluate up to 100 distinct analytes simultaneously in a single sample, in a 96-well plate format. This system has improved sensitivity versus existing microsphere-based assays and has sensitivity and precision comparable with or better than microarray technology. We have achieved detection levels down to 1 amol, detecting rare messages in complex cRNA samples, using as little as 2.5 Ī¼g starting cRNA. This assay offers increased throughput with decreased costs compared with existing microarray technologies, with the trade-off being in the total number of transcripts that can be analyzed
Dust heating sources in galaxies: the case of M33 (HERM33ES)
Dust emission is one of the main windows to the physics of galaxies and to
star formation as the radiation from young, hot stars is absorbed by the dust
and reemitted at longer wavelengths. The recently launched Herschel satellite
now provides a view of dust emission in the far-infrared at an unequaled
resolution and quality up to 500 \mu m. In the context of the Herschel HERM33ES
open time key project, we are studying the moderately inclined Scd local group
galaxy M33 which is located only 840 kpc away. In this article, using Spitzer
and Herschel data ranging from 3.6 \mu m to 500 \mu m, along with HI, H\alpha\
maps, and GALEX ultraviolet data we have studied the emission of the dust at
the high spatial resolution of 150 pc. Combining Spitzer and Herschel bands, we
have provided new, inclination corrected, resolved estimators of the total
infrared brightness and of the star formation rate from any combination of
these bands. The study of the colors of the warm and cold dust populations
shows that the temperature of the former is, at high brightness, dictated by
young massive stars but, at lower brightness, heating is taken over by the
evolved populations. Conversely, the temperature of the cold dust is tightly
driven by the evolved stellar populations.Comment: 29 pages, 12 figures, accepted for publication in A
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