397 research outputs found

    Resolution-enhanced Mapping Spectrometer

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    A familiar mapping spectrometer implementation utilizes two dimensional detector arrays with spectral dispersion along one direction and spatial along the other. Spectral images are formed by spatially scanning across the scene (i.e., push-broom scanning). For imaging grating and prism spectrometers, the slit is perpendicular to the spatial scan direction. For spectrometers utilizing linearly variable focal-plane-mounted filters the spatial scan direction is perpendicular to the direction of spectral variation. These spectrometers share the common limitation that the number of spectral resolution elements is given by the number of pixels along the spectral (or dispersive) direction. Resolution enhancement by first passing the light input to the spectrometer through a scanned etalon or Michelson is discussed. Thus, while a detector element is scanned through a spatial resolution element of the scene, it is also temporally sampled. The analysis for all the pixels in the dispersive direction is addressed. Several specific examples are discussed. The alternate use of a Michelson for the same enhancement purpose is also discussed. Suitable for weight constrained deep space missions, hardware systems were developed including actuators, sensor, and electronics such that low-resolution etalons with performance required for implementation would weigh less than one pound

    Trajectory Mapping and Applications to Data from the Upper Atmosphere Research Satellite

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    The problem of creating synoptic maps from asynoptically gathered trace gas data has prompted the development of a number of schemes. Most notable among these schemes are the Kalman filter, the Salby-Fourier technique, and constituent reconstruction. This paper explores a new technique called trajectory mapping. Trajectory mapping creates synoptic maps from asynoptically gathered data by advecting measurements backward or forward in time using analyzed wind fields. A significant portion of this work is devoted to an analysis of errors in synoptic trajectory maps associated with the calculation of individual parcel trajectories. In particular, we have considered (1) calculational errors; (2) uncertainties in the values and locations of constituent measurements, (3) errors incurred by neglecting diabatic effects, and (4) sensitivity to differences in wind field analyses. These studies reveal that the global fields derived from the advection of large numbers of measurements are relatively insensitive to the errors in the individual trajectories. The trajectory mapping technique has been successfully applied to a variety of problems. In this paper, the following two applications demonstrate the usefulness of the technique: an analysis of dynamical wave-breaking events and an examination of Upper Atmosphere Research Satellite data accuracy

    Trajectory mapping: A tool for validation of trace gas observations

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    We investigate the effectiveness of trajectory mapping(TM) as a data validation tool. TM combines a dynamical model of the atmosphere with trace gas observations to provide more statistically robust estimates of instrument performance over much broader geographic areas than traditional techniques are able to provide. We present four detailed case studies selected so that the traditional techniques are expected to work well. In each case the TM results are equivalent to or improve upon the measurement comparisons performed with traditional approaches. The TM results are statistically more robust than those achieved using traditional approaches since the TM comparisons occur over a much larger range of geophysical variability. In the first case study we compare ozone data from the Halogen Occultation Experiment (HALOE) with Microwave Limb Sounder(MLS). TM comparisons appear to introduce little to no error as compared to the traditional approach. In the second case study we compare ozone data from HALOE with that from the Stratospheric Aerosol and Gas Experiment TT(SAGE TT). TM results in differences of less than 5% as compared to the traditional approach at altitudes between 18 and 25 km and less than 10% at altitudes between 25 and 40 km.In the third case study we show that ozone profiles generated from HALOE data using TM compare well with profiles from five European ozonesondes. In the fourth case study we evaluate the precision of MLS H20 using TM and find typical precision uncertainties of 3-7% at most latitudes and altitudes. The TM results agree well with previous estimates but are the result of a global analysis of the data rather than an analysis in the limited latitude bands in which traditional approaches work. Finally, sensitivity studies using the MLS H20 data show the following: (1) a combination of forward and backward trajectory calculations minimize uncertainties in isentropic TM; (2) although the uncertainty of the technique increases with trajectory duration,TM calculations of up to 14 days can provide reliable information for use in data validation studies; (3) a correlation coincidence criterion of 400 km produces the best TM results under most circumstances; (4) TM performs well compared to (and sometimes better than) traditional approaches at all latitudes and in most seasons and; (5) TM introduces no statistically significant biases at altitudes between 22 and 40 km

    The photochemistry of carbon monoxide in the stratosphere and mesosphere evaluated from observations by the Microwave Limb Sounder on the Aura satellite

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    The photochemical production and loss rates for carbon monoxide (CO) in the stratosphere and mesosphere are evaluated using measurements from the Aura Microwave Limb Sounder (MLS) and the Atmospheric Chemistry Experiment-Fourier Transform Spectrometer (ACE-FTS). The distributions of reactive trace gases involved in the photochemistry of CO, including OH, CH4, O(D-1), Cl, as well as temperatures for calculating reaction rates, are either directly observed or constrained from observations. We map the CO net production and loss as a function of pressure (10-0.02 hPa, about 30-75 km altitude), latitude (approximately +/- 70 degrees), and season. The results indicate that photochemical loss dominates over production for nearly all conditions considered here. A minimum photochemical loss lifetime of about 10 days occurs near the 2 hPa pressure level, and it follows the region of maximum sunlight exposure. At high latitudes during winter, the CO lifetime is generally longer than 30 days. Time scales become much shorter in spring, however, when CO lifetimes can be 15-20 days poleward of 60 degrees latitude in the upper stratosphere. On the basis of these results, CO is a suitable tracer during autumn to spring above the 0.1 hPa pressure level but not in the upper stratosphere near 1 hPa.</p

    Improving management of a mid-Atlantic coastal barrier island through assessment of habitat condition

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    AbstractTo achieve desired environmental outcomes, environmental condition and trends need to be rigorously measured and communicated to resource managers, scientists, and a broader general audience. However, there is often a disconnect between responsive ecosystem monitoring and decision making for strategic long-term management. This project demonstrates how historical monitoring data can be synthesized and used for future planning and decision making, thereby closing the management feedback cycle. This study linked disparate datasets, collected for a variety of purposes and across multiple temporal and spatial scales, in order to assess and quantify current habitat conditions. The results inform integrated resource management decision-making at Assateague Island National Seashore (Maryland and Virginia, USA) by using ecological reference conditions to identify monitoring needs, areas of high vulnerability, and areas with potential for improved management. The approach also provides a framework that can be applied in the future to assess the effectiveness of these management decisions on the condition of island habitats, and is a replicable demonstration of incorporating diverse monitoring datasets into an adaptive management cycle

    Improving together: better science writing through peer learning

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    Science, in our case the climate and geosciences, is increasingly interdisciplinary. Scientists must therefore communicate across disciplinary boundaries. For this communication to be successful, scientists must write clearly and concisely, yet the historically poor standard of scientific writing does not seem to be improving. Scientific writing must improve, and the key to long-term improvement lies with the early-career scientist (ECS). Many interventions exist for an ECS to improve their writing, like style guides and courses. However, momentum is often difficult to maintain after these interventions are completed. Continuity is key to improving writing. This paper introduces the ClimateSnack project, which aims to motivate ECSs to develop and continue to improve their writing and communication skills. The project adopts a peer-learning framework where ECSs voluntarily form writing groups at different institutes around the world. The group members learn, discuss, and improve their writing skills together. Several ClimateSnack writing groups have formed. This paper examines why some of the groups have flourished and others have dissolved. We identify the challenges involved in making a writing group successful and effective, notably the leadership of self-organized groups, and both individual and institutional time management. Within some of the groups, peer learning clearly offers a powerful tool to improve writing as well as bringing other benefits, including improved general communication skills and increased confidence

    A global inventory of stratospheric NOy from ACE-FTS

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    The Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) on board the Canadian SCISAT-1 satellite (launched in August 2003) measures over 30 different atmospheric species, including six nitrogen trace gases that are needed to quantify the stratospheric NOy budget. We combine volume mixing ratio (VMR) profiles for NO, NO2, HNO3, N2O5, ClONO2, and HNO4 to determine a zonally averaged NOy climatology on monthly and 3 month combined means (December–February, March–May, June–August, and September–November) at 5° latitude spacing and on 33 pressure surfaces. Peak NOy VMR concentrations (15–20 ppbv) are situated at about 3 hPa (∼40 km) in the tropics, while they are typically lower at about 10 hPa (∼30 km) in the midlatitudes. Mean NOy VMRs are similar in both the northern and southern polar regions, with the exception of large enhancements periodically observed in the upper stratosphere and lower mesosphere. These are primarily due to enhancements of NO due to energetic particle precipitation and downward transport. Other features in the NOy budget are related to descent in the polar vortex, heterogeneous chemistry, and denitrification processes. Comparison of the ACE-FTS NOy budget is made to both the Odin and ATMOS NOy data sets, showing in both cases a good level of agreement, such that relative differences are typically better than 20%. The NOy climatological products are available through the ACE website and are a supplement to the paper. - A middle-atmosphere NOy climatology has been produced using ACE-FTS measurements; - A robust method for quality controlling the input data has been developed - Good agreement is found between ACE-FTS NOy climatology and other climatologie

    Molecular Docking against SARS-CoV-2 Variants, Antiviral, Dynamics and Quantum Chemical Modeling of Mannopyranoside Derivatives

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    Researchers worldwide are prompting their hard and soul effort to develop the best possible therapeutic options to eliminate vaccination-related difficulties to effectively manage SARS-CoV-2, which is now sweeping the world. The present study was undertaken to investigate the computational properties of methyl α-D-mannopyranoside and its designed derivatives to assess their thermophysical and biochemical parameters. The PASS prediction score was reported to be 0.233&lt;Pa&lt;0.403 for antiviral, 0.473&lt;Pa&lt;0.569 for antibacterial, 0.628&lt;Pa&lt;0.680 for antifungal, and 0.242&lt;Pa&lt;0.349 for antibiotic. For this purpose, previously synthesized potential derivatives of methyl α-D-mannopyranoside were assessed with six different variants of the COVID-19 protein and docking studies by AutoDock. The highest binding affinity from the molecular docking score was obtained at -8.5 against the alpha variant (PDB ID 7EKF) in L06 against each of the SARS-CoV-2 targeted proteins. In addition, good energy values were found against the SARS-CoV-2 spike glycoprotein (PDB ID 6vxx), Omicron variant (PDB ID 7T9J) and Delta variant (PDB ID 7V8B). Although all the synthesized compounds have opposed to standard affinities, the docking scores of newly derivative compounds were found to be the highest in contrast to the alpha variant (PDB ID 7EKF) (-8.5 kcal/mol), where the standard Molnupiravir has been shown to be -6.9 kcal/mol against the alpha variant. In addition, all possible candidates for the new drug show an excellent pharmacokinetic profile, are noncarcinogenic, are highly water soluble, fulfill PASS prediction, and have drug-likeness that meets all the pharmacokinetic parameters. Therefore, this methyl-α-D-mannopyranoside and its derivatives might be useful to inhibit the mentioned COVID-19 variants as a potential drug(s) candidate

    Jordan Left Derivations of Two Torsion Free ГM – Modules

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    13-19Let M be a Г-ring and X be a 2-torsionfree left ГM-module. The purpose of this paper is to investigate Jordan left derivations on M considering aαbβc=aβbαc, for every a,b,c∈M and α,β∈Г . We show that the existence of a nonzero Jordan left derivation of M into X implies M is commutative. We also show that if X = M is a semiprime Г-ring, then the derivation is a mapping from M into its centre. Finally we show that if M is a prime Г- ring, then every Jordan left derivation d: M→ M is a left derivation

    The Bangladesh Risk of Acute Vascular Events (BRAVE) Study: objectives and design.

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    During recent decades, Bangladesh has experienced a rapid epidemiological transition from communicable to non-communicable diseases. Coronary heart disease (CHD), with myocardial infarction (MI) as its main manifestation, is a major cause of death in the country. However, there is limited reliable evidence about its determinants in this population. The Bangladesh Risk of Acute Vascular Events (BRAVE) study is an epidemiological bioresource established to examine environmental, genetic, lifestyle and biochemical determinants of CHD among the Bangladeshi population. By early 2015, the ongoing BRAVE study had recruited over 5000 confirmed first-ever MI cases, and over 5000 controls "frequency-matched" by age and sex. For each participant, information has been recorded on demographic factors, lifestyle, socioeconomic, clinical, and anthropometric characteristics. A 12-lead electrocardiogram has been recorded. Biological samples have been collected and stored, including extracted DNA, plasma, serum and whole blood. Additionally, for the 3000 cases and 3000 controls initially recruited, genotyping has been done using the CardioMetabochip+ and the Exome+ arrays. The mean age (standard deviation) of MI cases is 53 (10) years, with 88 % of cases being male and 46 % aged 50 years or younger. The median interval between reported onset of symptoms and hospital admission is 5 h. Initial analyses indicate that Bangladeshis are genetically distinct from major non-South Asian ethnicities, as well as distinct from other South Asian ethnicities. The BRAVE study is well-placed to serve as a powerful resource to investigate current and future hypotheses relating to environmental, biochemical and genetic causes of CHD in an important but under-studied South Asian population.The Gates Cambridge Trust has supported Dr Chowdhury. Epidemiological fieldwork in BRAVE has been supported by grants to investigators at the Cardiovascular Epidemiology Unit, University of Cambridge. The Cardiovascular Epidemiology Unit is underpinned by programme grants from the British Heart Foundation (RG/13/13/30194), the UK Medical Research Council (MR/L003120/1), and the UK National Institute of Health Research Cambridge Biomedical Research Centre. BRAVE has received support for genetic assays from the European Research Council (ERC-2010-AdG-20100317), European Commission Framework 7 (Grant Agreement number: 279233), and the Cambridge British Heart Foundation Centre for Excellence in Cardiovascular Science; We would like to acknowledge the contributions of the following individuals: Cardiology Research Group in Bangladesh Mohammad Afzalur Rahman, Mohammad Abdul Kader Akanda, M Atahar Ali, Mir Jamal Uddin, SM Siddiqur Rahman, Amal Kumar Choudhury, Md. Mamunur Rashid, Nazir Ahmed Chowdhury, Mohammad Abdullahel Baqui, Kajal Kumar Karmoker, Mohammad Golam Azam; Setting up/implementation of fieldwork in Bangladesh Abbas Bhuiya, Susmita Chowdhury, Kamrun Nahar, Neelima Das, Proshon Roy, Sumona Ferdous, Taposh Kumar Biswas, Abu Sadat Mohammad Sayed Sharif, Ranjit Shingha, Rose Jinnath Tomas, Babulal Parshei, Mabubur Rahman, Mohammad Emon Hossain, Akhirunnesa Mily, AK Mottashir Ahmed, Sati Chowdhury, Sushila Roy, Dipak Kanti Chowdhury, Swapan Kumar Roy; Epidemiological/statistical support in Cambridge Stephen Kaptoge, Simon Thompson, Angela Wood, Narinder Bansal, Anna Ramond, Clare Oliver-Williams, Marinka Steur, Linda O’Keeffe, Eleni Sofianopoulou, Setor Kunutsor, Donal Gorman, Oscar H Franco, Malcolm Legget, Pinal Patel, Marc Suhrcke, Sylvaine Bruggraber, Jonathan Powell; Data management Matthew Walker, Steve Ellis, Shawkat Jahangir, Habibur Rahman, Rifat Hasan Shammi, Shafqat Ullah, Mohammad Abdul Matin and Administration Beth Collins, Hannah Lombardi, Binder Kaur, Rachel Henry, Marilena Papanikolaou, Robert Smith, Abdul Wazed, Robert Williams, Julie Jenkins, Keith Hoddy.This is the final published version of the article. It was originally published in the European Journal of Epidemiology (Chowdhury R, et al., European Journal of Epidemiology, 2015, doi:10.1007/s10654-015-0037-2). The final version is available at http://dx.doi.org/10.1007/s10654-015-0037-
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