1,875 research outputs found

    Coverage and density of a low power, low data rate, spread spectrum wireless sensor network for agricultural monitoring

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    A physical layer specification for a low power, low complexity, low data rate sensor network suitable for agricultural monitoring is investigated. Code division multiple access (CDMA) with high processing gain is used to facilitate transmission powers which comply with the Ultra Wide Band (UWB) spectral mask, and this permits physically small nodes with limited energy storage capacity. The interference arising from each node is calculated, and it is shown that for the investigated scenario and specification, an aggregate data rate of 2 bytes per minute and a node population of approximately 1000 can be supported at distances up to a few kilometres from the central node, with less than 0.2% chance of failure due to multiple access interference

    Firing behavior of Missouri plastic fire clay

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    There are two districts in Missouri in which plastic fire clay occurs. The oldest and least significant of these deposits is the Cheltenham , in the St. Louis area. The most prominent area in which plastic fire clay occurs is generally termed the east central district. Included in this district are Calloway, Montgomery, Audrain, Warren, Boone, Monroe, Pike and Lincoln Counties. The clay as tested in this report occurs in Boone County, near Columbia. A plastic fire clay does not have as high a P.C.E. (pyrometric cone equivalent) as the ordinary flint and semi-flint clays, but its high plasticity warrants its use in the manufacture of refractories as an aid in the forming process. Plastic fire clays are also used in the production of second-grade refractory products. The chief difference between plastic fire clay and semi-flint clay is that the plastic fire clay contains more impurities and has a higher alkali content --Introduction, page 1

    Letter from H. E. Crockett

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    Letter concerning payments for notes

    Counselors in Training Educational Impacts and Perceived Adequacy of Supports Amidst COVID-19

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    Counselors-in-Training (CITs) experience complex challenges, stressors, and changes during the COVID-19 pandemic and concurrent sociopolitical crises. The authors examined CIT’s academic and clinical experiences during the first year of COVID-19, including their perception of the adequacy of their training and supports to provide counseling during this time. Many CITs experienced a range of changes including transitioning from face-to-face training and supervision to distance learning, telehealth, and telesupervision. The authors discuss implications for training and supervision, including considerations related to distance learning and digital competence

    Basic Needs Adversities Among Counselors in Training: A Cluster Analysis

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    During the intersection of COVID-19 with ongoing identity-based injustices in the US, Counselors-in-Training (CITs) experience unprecedented challenges including new or exacerbated basic needs insecurity. In this descriptive study, the authors examined Basic Needs Adversities (BNA) in a national sample of CITs (n = 233) during the first year of the COVID-19 pandemic. The authors used cluster analysis to investigate CITs reported BNAs and identified four subgroups of participants based on similarities and dissimilarities in the number and type of BNAs endorsed. The authors discuss implications for training and supervision with a focus on social justice in counselor education

    Herschel observations of EXtra-Ordinary Sources: Analysis of the HIFI 1.2 THz Wide Spectral Survey Toward Orion KL II. Chemical Implications

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    We present chemical implications arising from spectral models fit to the Herschel/HIFI spectral survey toward the Orion Kleinmann-Low nebula (Orion KL). We focus our discussion on the eight complex organics detected within the HIFI survey utilizing a novel technique to identify those molecules emitting in the hottest gas. In particular, we find the complex nitrogen bearing species CH3_{3}CN, C2_{2}H3_{3}CN, C2_{2}H5_{5}CN, and NH2_{2}CHO systematically trace hotter gas than the oxygen bearing organics CH3_{3}OH, C2_{2}H5_{5}OH, CH3_{3}OCH3_{3}, and CH3_{3}OCHO, which do not contain nitrogen. If these complex species form predominantly on grain surfaces, this may indicate N-bearing organics are more difficult to remove from grain surfaces than O-bearing species. Another possibility is that hot (Tkin_{\rm kin}∌\sim300 K) gas phase chemistry naturally produces higher complex cyanide abundances while suppressing the formation of O-bearing complex organics. We compare our derived rotation temperatures and molecular abundances to chemical models, which include gas-phase and grain surface pathways. Abundances for a majority of the detected complex organics can be reproduced over timescales ≳\gtrsim 105^{5} years, with several species being under predicted by less than 3σ\sigma. Derived rotation temperatures for most organics, furthermore, agree reasonably well with the predicted temperatures at peak abundance. We also find that sulfur bearing molecules which also contain oxygen (i.e. SO, SO2_{2}, and OCS) tend to probe the hottest gas toward Orion KL indicating the formation pathways for these species are most efficient at high temperatures.Comment: 31 pages, 6 figures, 1 Table, accepted to the Astrophysical Journa

    A Direct Measurement of the Total Gas Column Density in Orion KL

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    The large number of high-J lines of C^(18)O available via the Herschel Space Observatory provide an unprecedented ability to model the total CO column density in hot cores. Using the emission from all the observed lines (up to J = 15-14), we sum the column densities in each individual level to obtain the total column after correcting for the population in the unobserved states. With additional knowledge of source size, V_(LSR), and line width, and both local thermodynamic equilibrium (LTE) and non-LTE modeling, we have determined the total C^(18)O column densities in the Extended Ridge, Outflow/Plateau, Compact Ridge, and Hot Core components of Orion KL to be 1.4 × 10^(16) cm^(–2), 3.5 × 10^(16) cm^(–2), 2.2 × 10^(16) cm^(–2), and 6.2 × 10^(16) cm^(–2), respectively. We also find that the C^(18)O/C^(17)O abundance ratio varies from 1.7 in the Outflow/Plateau, 2.3 in the Extended Ridge, 3.0 in the Hot Core, and to 4.1 in the Compact Ridge. This is in agreement with models in which regions with higher ultraviolet radiation fields selectively dissociate C^(17)O, although care must be taken when interpreting these numbers due to the size of the uncertainties in the C^(18)O/C^(17)O abundance ratio
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