scholarly journals Quantifying ionospheric effects on global 21-cm observations

2021 ◽  
Vol 503 (1) ◽  
pp. 344-353
Author(s):  
Emma Shen ◽  
Dominic Anstey ◽  
Eloy de Lera Acedo ◽  
Anastasia Fialkov ◽  
Will Handley
Keyword(s):  
Parameter Space ◽  
Spatial Model ◽  
Ionospheric Effects ◽  
Temporal Variance ◽  
Foreground Calibration ◽  
Over Time

ABSTRACT We modelled the two major layer of Earth’s ionosphere, the F-layer and the D-layer, by a simplified spatial model with temporal variance to study the chromatic ionospheric effects on global 21-cm observations. From the analyses, we found that the magnitude of the ionospheric disruptions due to ionospheric refraction and absorption can be greater than the expected global 21-cm signal, and the variation of its magnitude can differ, depending on the ionospheric conditions. Within the parameter space adopted in the model, the shape of the global 21-cm signal is distorted after propagating through the ionosphere, while its amplitude is weakened. It is observed that the ionospheric effects do not cancel out over time, and thus should be accounted for in the foreground calibration at each timestep to account for the chromaticity introduced by the ionosphere.

scholarly journals Spatial and Temporal Variation in an Apple Orchard

HortScience ◽  
2019 ◽  
Vol 54 (12) ◽  
pp. 2182-2187
Author(s):  
Babak Talebpour ◽  
Maksut Barış Eminoğlu ◽  
Uğur Yegül ◽  
Ufuk Türker
Keyword(s):  
Temporal Variation ◽  
Precision Agriculture ◽  
Temporal Stability ◽  
Apple Orchard ◽  
The Other ◽  
Spatial And Temporal Variation ◽  
Spatial And Temporal Variability ◽  
Research Station ◽  
Temporal Variance ◽  
Over Time

One important goal of precision horticulture (PH), as well as precision agriculture (PA), is to measure and manage spatial and temporal variation in orchards. In this study, temporal and spatial analysis of yields were carried out over 2 years for a 0.5-ha apple orchard (at the Haymana Research Station of Ankara University, Turkey, from 2017 to 2018) to determine the variability of yields over time and included seven apple varieties: ‘Royal Gala’, ‘Red Chief’, ‘Braeburn’, ‘Mondial Gala’, ‘Jonagold’, ‘Fuji’, and ‘Mitch Gala’. To achieve this, yield data for two different years were analyzed for mean yield, temporal variance, and cv in terms of spatial and temporal stability, and their yield maps were produced. The results showed that ‘Jonagold’, ‘Braeburn’, and ‘Red Chief’ varieties yielded less than the average yield, whereas the other varieties produced average yields when the yield from 2 years was taken into account. Calculation of the values for determining temporal stability over time resulted in all existing varieties being identified as stable over time. For example, the ‘Jonagold’ and ‘Red Chief’ varieties showed 100% stability in terms of temporal variance. Results also showed that the ‘Gala’ varieties were stable for 2 years and produced high yields, whereas the other varieties were specified as stable and low yielding when spatial and temporal variability was considered in combination.

scholarly journals Estimating the Suitability for the Reintroduced Arabian Oryx (Oryx leucoryx, Pallas 1777) of Two Desert Environments by NIRS-Aided Fecal Chemistry

2021 ◽  
Vol 13 (10) ◽  
pp. 1876
Author(s):  
Serge Yan Landau ◽  
Ido Isler ◽  
Levana Dvash ◽  
Benny Shalmon ◽  
Amir Arnon ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Infrared Spectroscopy ◽  
Nutritional Status ◽  
Near Infrared ◽  
Home Ranges ◽  
Temporal Variance ◽  
Dietary Component ◽  
Arabian Oryx ◽  
Reintroduced Population ◽  
Over Time

The re-introduction paradigm is that Arabian Oryx (Oryx leucoryx) herds adjust the size of their home ranges depending on the availability of vegetation, which is directly related to rainfall. In Israel, Arabian oryx were released in two hyper-arid sites: the Arava Valley and in the Paran wilderness, belonging to the Sudanese and the Saharo–Arabian biogeographic zones, respectively. While post-release survival was similar in both, reproductive success in the Paran wilderness reintroduction site was extremely low, resulting in an acute decline of the reintroduced population over time. The hypothesis that impaired nutrition might be associated with this finding was assessed with near-infrared spectroscopy (NIRS)-aided chemistry of monthly sampled fecal pellets, used as remote sensing evidence of ingested diets, throughout a year. Fecal nitrogen (FN), used as an estimate of nutritional status, was consistently higher in the Arava. Grass was never the sole or even a major dietary component. The dietary contribution of tannin-rich browse was high and steady all year-round in the Arava and increased steadily in Paran from winter to summer, corresponding to the period of availability of Acacia raddiana pods in both regions. The oryx in Paran had a home-range that was ten-fold, compared to the Arava, suggesting less feed availability. Acacia browsing may mitigate the effects of temporal variance in primary production. Under such conditions, oryx should be preferably released in areas that support significant acacia stands.

scholarly journals The Impact of Political Uncertainty: A Robust Control Approach

2016 ◽  
Vol 16 (2) ◽  
pp. 837-863 ◽  
Author(s):  
Robert Baumann ◽  
Justin Svec
Keyword(s):  
Robust Control ◽  
Spatial Model ◽  
Optimization Problem ◽  
Political Uncertainty ◽  
Political Candidates ◽  
Policy Positions ◽  
Control Approach ◽  
Mere Presence ◽  
The Impact ◽  
Over Time

Abstract We examine how candidate uncertainty affects the policy platforms chosen in a unidimensional, two-candidate Downsian spatial model. The candidates, we assume, do not know the true distribution of voters. Following the robust control literature, candidates respond to this uncertainty by applying a max–min operator to their optimization problem. This approach, consistent with findings within the behavioral economics literature, protects the candidate by ensuring that her expected utility never falls too far, regardless of the true voter distribution. We show that this framework produces a continuum of equilibria upon which the candidates can converge and that the size of this continuum is weakly increasing in each candidate’s uncertainty. We argue that our model can explain movements in political platforms over time. That is, the mere presence of candidate uncertainty, in addition to shifts in attitudes or demographics, can cause political candidates to change their policy positions across elections.

Why Small, Centrist Third Parties Motivate Policy Divergence by Major Parties

2006 ◽  
Vol 100 (3) ◽  
pp. 403-417 ◽  
Author(s):  
JAMES ADAMS ◽  
SAMUEL MERRILL
Keyword(s):  
Spatial Model ◽  
Sufficient Conditions ◽  
Third Parties ◽  
Necessary And Sufficient Conditions ◽  
Third Party ◽  
Explicit Formulas ◽  
The Third ◽  
The Third Party ◽  
Necessary And Sufficient ◽  
Over Time

Plurality-based elections between two major parties or candidates sometimes feature small, centrist, third parties. We modify the standard two-party spatial model of policy-seeking parties to incorporate a centrist third party, and we show that the presence of such a party—even if it has no chance of winning—motivates the major parties to propose policies that are much more divergent than without the third party. We derive explicit formulas for party locations at a three-party equilibrium and provide necessary and sufficient conditions for existence of that equilibrium. We show that, over time, the major parties can be expected to shift their policies in thesamedirection relative to each other but in theoppositedirection relative to the minor party. The predictions of this model are compared with estimates of party policy locations during appropriate periods in postwar Britain.

Revisiting the Role of Caves and Rockshelters in the Hunter-Gatherer Taskscape of the Archaic Midsouth

2015 ◽  
Vol 80 (2) ◽  
pp. 332-352 ◽  
Author(s):  
Lara Homsey-Messer
Keyword(s):  
Symbolic Meaning ◽  
Hunter Gatherers ◽  
Middle Holocene ◽  
Temporal Variance ◽  
Middle Archaic ◽  
Spatio Temporal ◽  
And Function ◽  
Over Time

This paper evaluates previous models of cave and rockshelter use in the American Midsouth from the Early to the Middle Archaic periods. Four sites are compared in order to identify variability in activities, seasonality, occupation intensity, and function. Focus is placed on using the often overlooked feature assemblages to discern these activities. Data suggest that the changing use of many caves and rockshelters is not one of longer term occupation as base camps, as has been previously argued, but rather as specialized field camps dedicated to the processing of mast resources. This shift takes place as Middle Holocene warming prompted hunter-gatherers to adopt a more logistical mobility strategy in order to take advantage of the spatio-temporal variance associated with increased mast availability. It is further argued that these sites were likely locations of women's activities and that foraging in the Midsouth involved groups of women engaged in daily tasks centered around mast, tasks that over time imbued caves and rockshelter s with symbolic meaning such that they came to function simultaneously as both processing camps and as persistent places of ritual significance in the hunter-gatherer taskscape.

SPATIAL PATTERN IN AN EPIDEMIC SYSTEM WITH CROSS-DIFFUSION OF THE SUSCEPTIBLE

2009 ◽  
Vol 17 (01) ◽  
pp. 141-152 ◽  
Author(s):  
GUI-QUAN SUN ◽  
ZHEN JIN ◽  
QUAN-XING LIU ◽  
LI LI
Keyword(s):  
Pattern Formation ◽  
Spatial Pattern ◽  
Numerical Simulations ◽  
Parameter Space ◽  
Spatial Model ◽  
Great Influence ◽  
Phase Dynamics ◽  
Cross Diffusion

In this paper, pattern formation of a spatial model with cross diffusion of the susceptible is investigated. We compute Hopf and Turing bifurcations for the model. In particular, the exact Turing domain is delineated in the parameter space. When the parameters are in that domain, a series of numerical simulations reveals that the typical dynamics of the infecteds class typically involves the formation of isolated groups, i.e., striped, spotted or labyrinthine patterns. Furthermore, spatial oscillatory and anti-phase dynamics of different spatial points were also found. These results demonstrate that cross diffusion of susceptibles may have great influence on the spread of the epidemic.

Social transmission bias and the cultural evolution of folk-economic beliefs

2018 ◽  
Vol 41 ◽  
Author(s):  
David Hirshleifer ◽  
Siew Hong Teoh
Keyword(s):  
Cultural Evolution ◽  
Social Transmission ◽  
Cognitive Approach ◽  
Economic Problems ◽  
Economic Attitudes ◽  
The Social ◽  
Economic Beliefs ◽  
Over Time

AbstractEvolved dispositions influence, but do not determine, how people think about economic problems. The evolutionary cognitive approach offers important insights but underweights the social transmission of ideas as a level of explanation. The need for asocialexplanation for the evolution of economic attitudes is evidenced, for example, by immense variations in folk-economic beliefs over time and across individuals.

Articulatory Generalization in Two Word-Medial, Ambisyllabic Contexts

1988 ◽  
Vol 19 (3) ◽  
pp. 251-258 ◽  
Author(s):  
Virginia I. Wolfe ◽  
Suzanne D. Blocker ◽  
Norma J. Prater
Keyword(s):  
Common View ◽  
Perceptual Salience ◽  
The Common ◽  
Unitary Concept ◽  
Over Time

Articulatory generalization of velar cognates /k/, /g/ in two phonologically disordered children was studied over time as a function of sequential word-morpheme position training. Although patterns of contextual acquisition differed, correct responses to the word-medial, inflected context (e.g., "picking," "hugging") occurred earlier and exceeded those to the word-medial, noninflected context (e.g., "bacon," "wagon"). This finding indicates that the common view of the word-medial position as a unitary concept is an oversimplification. Possible explanations for superior generalization to the word-medial, inflected position are discussed in terms of coarticulation, perceptual salience, and the representational integrity of the word.

Treatment Fidelity Procedures for an Aphasia Intervention Within a Randomized Controlled Trial: Design, Feasibility, and Results

2020 ◽  
Vol 29 (1S) ◽  
pp. 412-424
Author(s):  
Elissa L. Conlon ◽  
Emily J. Braun ◽  
Edna M. Babbitt ◽  
Leora R. Cherney
Keyword(s):  
Randomized Controlled Trial ◽  
Controlled Trial ◽  
Treatment Protocol ◽  
Treatment Fidelity ◽  
Protocol Adherence ◽  
Study Condition ◽  
Randomized Controlled ◽  
Aphasia Therapy ◽  
Percent Accuracy ◽  
Over Time

Purpose This study reports on the treatment fidelity procedures implemented during a 5-year randomized controlled trial comparing intensive and distributed comprehensive aphasia therapy. Specifically, the results of 1 treatment, verb network strengthening treatment (VNeST), are examined. Method Eight participants were recruited for each of 7 consecutive cohorts for a total of 56 participants. Participants completed 60 hr of aphasia therapy, including 15 hr of VNeST. Two experienced speech-language pathologists delivered the treatment. To promote treatment fidelity, the study team developed a detailed manual of procedures and fidelity checklists, completed role plays to standardize treatment administration, and video-recorded all treatment sessions for review. To assess protocol adherence during treatment delivery, trained research assistants not involved in the treatment reviewed video recordings of a subset of randomly selected VNeST treatment sessions and completed the fidelity checklists. This process was completed for 32 participants representing 2 early cohorts and 2 later cohorts, which allowed for measurement of protocol adherence over time. Percent accuracy of protocol adherence was calculated across clinicians, cohorts, and study condition (intensive vs. distributed therapy). Results The fidelity procedures were sufficient to promote and verify a high level of adherence to the treatment protocol across clinicians, cohorts, and study condition. Conclusion Treatment fidelity strategies and monitoring are feasible when incorporated into the study design. Treatment fidelity monitoring should be completed at regular intervals during the course of a study to ensure that high levels of protocol adherence are maintained over time and across conditions.

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