scholarly journals Effect of Upper- and Lower-Level Baroclinicity on the Persistence of the Leading Mode of Midlatitude Jet Variability

2018 ◽  
Vol 76 (1) ◽  
pp. 155-169
Author(s):  
Loïc Robert ◽  
Gwendal Rivière ◽  
Francis Codron
Keyword(s):  
Zonal Wind ◽  
Propagation Regime ◽  
Leading Mode ◽  
The Mean ◽  
Upper Level ◽  
Jet Variability ◽  
Quasigeostrophic Model ◽  
The Impact ◽  
The Waves ◽  
Critical Latitude

Abstract The sensitivity of the variability of an eddy-driven jet to the upper- and lower-level baroclinicity of the mean state is analyzed using a three-level quasigeostrophic model on the sphere. The model is forced by a relaxation in temperature to a steady, zonally symmetric profile with varying latitude and intensity of the maximum baroclinicity. The leading EOF of the zonally and vertically averaged zonal wind is characterized by a meridional shift of the eddy-driven jet. While changes in the upper-level baroclinicity have no significant impact on the persistence of this leading EOF, an increase in lower-level baroclinicity leads to a reduced persistence. For small lower-level baroclinicity, the leading EOF follows a classical zonal index regime, for which the meridional excursions of the zonal wind anomalies are maintained by a strong positive eddy feedback. For strong lower-level baroclinicity, the jet enters a poleward-propagation regime, for which the eddy forcing continuously acts to push the jet poleward and prevents its maintenance at a fixed latitude. The enhanced poleward propagation when the lower-level baroclinicity increases is interpreted as resulting from the broader and weaker potential vorticity gradient that enables the waves to propagate equatorward and facilitates the poleward migration of the critical latitude. Finally, the decrease in the persistence of the leading EOF as the lower-level baroclinicity increases is shown not to result from the impact of changes in the mean climatological jet latitude.

scholarly journals The Impact of Baroclinic Eddy Feedback on the Persistence of Jet Variability in the Two-Layer Model

2013 ◽  
Vol 71 (1) ◽  
pp. 410-429 ◽  
Author(s):  
Pablo Zurita-Gotor ◽  
Javier Blanco-Fuentes ◽  
Edwin P. Gerber
Keyword(s):  
Heat Flux ◽  
Low Frequency ◽  
Effective Diffusivity ◽  
Mean Flow ◽  
Eddy Heat Flux ◽  
Large Correlation ◽  
Low Frequency Variability ◽  
Upper Level ◽  
Jet Variability ◽  
The Impact

Abstract Although it is well known that the persistence of extratropical jet shifts is enhanced by a positive eddy feedback, the dynamics of this feedback is still debated. Two types of mechanisms have been proposed: barotropic mechanisms rely on changes in upper-level propagation and baroclinic mechanisms rely on the coupling between barotropic and baroclinic flow. Recent studies have suggested that barotropic models can capture key aspects of the observed jet variability but the role of baroclinic dynamics has been less explored. This study investigates the temporal relations between barotropic and baroclinic anomalies and their eddy forcings during the internal variability of the simple two-layer quasigeostrophic model. A large correlation is found between barotropic and baroclinic anomalies and between the meridional and vertical components of the Eliassen–Palm divergence, especially at low frequency. The low-frequency variability is consistent with the baroclinic mechanism: persistent upper-level eddy momentum convergence is associated with (and precedes) persistent anomalies in the poleward eddy heat flux. In contrast, at high frequency, poleward heat flux anomalies are associated with eddy momentum divergence aloft and both eddy forcings have same-sign contributions to the upper-level eddy potential vorticity (PV) flux. In this limit the eddy PV flux is associated with wave activity transience as effective diffusivity is too small to dissipate the wave–mean flow interaction term. The large correlation between barotropic and baroclinic anomalies implies that the low-frequency variability of barotropic flow may be affected by thermal damping when this damping is sufficiently strong. For example, zonal index persistence drops drastically in our model when baroclinicity shifts are prevented by strong thermal restoration.

scholarly journals A new index for the wintertime southern hemispheric split jet

2018 ◽  
Vol 18 (9) ◽  
pp. 6749-6760 ◽  
Author(s):  
Stella Babian ◽  
Jens Grieger ◽  
Ulrich Cubasch
Keyword(s):  
Zonal Wind ◽  
Southern Oscillation ◽  
Low Frequency ◽  
Teleconnection Patterns ◽  
Regional Feature ◽  
The Pacific ◽  
Upper Level ◽  
Jet Variability ◽  
The Individual ◽  
The Relationship

Abstract. One of the most prominent asymmetric features of the southern hemispheric (SH) circulation is the split jet over Australia and New Zealand in austral winter. Previous studies have developed indices to detect the degree to which the upper-level midlatitude westerlies are split and investigated the relationship between split events and the low-frequency teleconnection patterns, viz. the Antarctic Oscillation (AAO) and the El Niño–Southern Oscillation (ENSO). As the results were inconsistent, the relationship between the wintertime SH split jet and the climate variability indices remains unresolved and is the focus of this study. Until now, all split indices' definitions were based on the specific region where the split jet is recognizable. We consider the split jet as hemispheric rather than a regional feature and propose a new, hemispherical index that is based on the principal components (PCs) of the zonal wind field for the SH winter. A linear combination of PC2 and PC3 of the anomalous monthly (JAS) zonal wind is used to identify split-jet conditions. In a subsequent correlation analysis, our newly defined PC-based split index (PSI) indicates a strong coherence with the AAO. However, this significant relationship is unstable over the analysis period; during the 1980s, the AAO amplitude was higher than the PSI, and vice versa in the 1990s. It is probable that the PSI, as well as the AAO, underlie low-frequency variability on the decadal to centennial timescales, but the analyzed period is too short to draw these conclusions. A regression analysis with the Multivariate ENSO Index points to a nonlinear relationship between PSI and ENSO; i.e., split jets occur during both strong positive and negative phases of ENSO but rarely under “normal” conditions. The Pacific South American (PSA) patterns, defined as the second and third modes of the geopotential height variability at 500 hPa, correlate poorly with the PSI (rPSA−1 ≈ 0.2 and rPSA-2= 0.06), but significantly with the individual components (PCs) of the PSI, revealing an indirect influence on the SH split-jet variability. Our study suggests that the wintertime SH split jet is strongly associated with the AAO, while ENSO is to a lesser extent connected to the PSI. We conclude that a positive AAO phase, as well as both flavors of ENSO and the PSA-1 pattern produce favorable conditions for a SH split event.

Asteroid and Comet Impact Speeds upon Mars: Significance for Panspermia and the Supply of Organics

1997 ◽  
Vol 161 ◽  
pp. 197-201 ◽  
Author(s):  
Duncan Steel
Keyword(s):  
Probability Distributions ◽  
Regions Of Interest ◽  
Significant Fraction ◽  
Organic Chemicals ◽  
Impact Speed ◽  
The Mean ◽  
The Impact

AbstractWhilst lithopanspermia depends upon massive impacts occurring at a speed above some limit, the intact delivery of organic chemicals or other volatiles to a planet requires the impact speed to be below some other limit such that a significant fraction of that material escapes destruction. Thus the two opposite ends of the impact speed distributions are the regions of interest in the bioastronomical context, whereas much modelling work on impacts delivers, or makes use of, only the mean speed. Here the probability distributions of impact speeds upon Mars are calculated for (i) the orbital distribution of known asteroids; and (ii) the expected distribution of near-parabolic cometary orbits. It is found that cometary impacts are far more likely to eject rocks from Mars (over 99 percent of the cometary impacts are at speeds above 20 km/sec, but at most 5 percent of the asteroidal impacts); paradoxically, the objects impacting at speeds low enough to make organic/volatile survival possible (the asteroids) are those which are depleted in such species.

Sound Production Treatment for Acquired Apraxia of Speech: An Examination of Dosage in Relation to Probe Performance

2020 ◽  
pp. 1-16
Author(s):  
Julie L. Wambaugh ◽  
Lydia Kallhoff ◽  
Christina Nessler
Keyword(s):  
Retrospective Analysis ◽  
Sound Production ◽  
Apraxia Of Speech ◽  
Practice Schedule ◽  
Practice Schedules ◽  
Baseline Performance ◽  
The Mean ◽  
Number Of Treatment ◽  
The Impact

Purpose This study was designed to examine the association of dosage and effects of Sound Production Treatment (SPT) for acquired apraxia of speech. Method Treatment logs and probe data from 20 speakers with apraxia of speech and aphasia were submitted to a retrospective analysis. The number of treatment sessions and teaching episodes was examined relative to (a) change in articulation accuracy above baseline performance, (b) mastery of production, and (c) maintenance. The impact of practice schedule (SPT-Blocked vs. SPT-Random) was also examined. Results The average number of treatment sessions conducted prior to change was 5.4 for SPT-Blocked and 3.9 for SPT-Random. The mean number of teaching episodes preceding change was 334 for SPT-Blocked and 179 for SPT-Random. Mastery occurred within an average of 13.7 sessions (1,252 teaching episodes) and 12.4 sessions (1,082 teaching episodes) for SPT-Blocked and SPT-Random, respectively. Comparisons of dosage metric values across practice schedules did not reveal substantial differences. Significant negative correlations were found between follow-up probe performance and the dosage metrics. Conclusions Only a few treatment sessions were needed to achieve initial positive changes in articulation, with mastery occurring within 12–14 sessions for the majority of participants. Earlier occurrence of change or mastery was associated with better follow-up performance. Supplemental Material https://doi.org/10.23641/asha.12592190

Impact of changing rainfall conditions on surface and groundwater resources in an experimental watershed in Greece

2013 ◽  
Vol 12 (2) ◽  
pp. 119-125
Keyword(s):  
Groundwater Resources ◽  
Annual Runoff ◽  
Annual Rainfall ◽  
Rainfall Regime ◽  
Winter Rainfall ◽  
Rainfall Depth ◽  
Rainfall Volume ◽  
The Mean ◽  
Groundwater Reserves ◽  
The Impact

The present study concerns the impact of a change in the rainfall regime on surface and groundwater resources in an experimental watershed. The research is conducted in a gauged mountainous watershed (15.18 km2) that is located on the eastern side of Penteli Mountain, in the prefecture of Attica, Greece and the study period concerns the years from 2003 to 2008. The decrease in the annual rainfall depth during the last two hydrological years 2006-2007, 2007-2008 is 10% and 35%, respectively, in relation to the average of the previous years. In addition, the monthly distribution of rainfall is characterized by a distinct decrease in winter rainfall volume. The field measurements show that this change in rainfall conditions has a direct impact on the surface runoff of the watershed, as well as on the groundwater reserves. The mean annual runoff in the last two hydrological years has decreased by 56% and 75% in relation to the average of the previous years. Moreover, the groundwater level follows a declining trend and has dropped significantly in the last two years.

(Preprint)

2018 ◽  
Author(s):  
Natalia Banasik ◽  
Dariusz Jemielniak ◽  
Wojciech P?dzich
Keyword(s):  
Medical Condition ◽  
Extended Period ◽  
Well Being ◽  
Marginal Effect ◽  
Life Duration ◽  
Significant Difference ◽  
The Mean ◽  
Academic Teachers ◽  
Length Of Life ◽  
The Impact

BACKGROUND There have been mixed results of the studies checking whether prayers do actually extend the life duration of the people prayed for. Most studies on the topic included a small number of prayers and most of them focused on people already struggling with a medical condition. Intercessory prayer’s influence on health is of scholarly interest, yet it is unclear if its effect may be dependent on the number of prayers for a named individual received per annum. OBJECTIVE We sought to examine if there is a noticeable increased longevity effect of intercessory prayer for a named individual’s well-being, if he receives a very high number of prayers per annum for an extended period. METHODS We retrieved and conducted a statistical analysis of the data about the length of life for 857 Roman Catholic bishops, 500 Catholic priests, and 3038 male academics from the US, France, Italy, Poland, Brazil, and Mexico. We obtained information for these individuals who died between 1988 and 2018 from Wikidata, and conducted an observational cohort study. Bishops were chosen for the study, as they receive millions of individual prayers for well being, according to conservative estimates. RESULTS There was a main effect for occupation F(2, 4391) = 4.07, p = .017, ηp 2 = .002, with pairwise comparisons indicating significant differences between the mean life duration of bishops (M=30489) and of priests (M=29894), but none between the academic teachers (M=30147) and either of the other groups. A comparison analysis between bishops from the largest and the smallest dioceses showed no significant difference t(67.31)=1.61, p = .11. Our main outcome measure is covariance of the mean length of life in each of the categories: bishops, priests, academic teachers, controlled for nationality. CONCLUSIONS The first analysis proved that bishops live longer than priests, but due to a marginal effect size this result should be treated with caution. No difference was found between the mean length of life of bishops from the largest and the smallest dioceses. We found no difference between bishops and male academics. These results show that the impact of intercessory prayers on longevity is not observable.

scholarly journals Mean Empirical Likelihood Inference for Response Mean with Data Missing at Random

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Hanji He ◽  
Guangming Deng
Keyword(s):  
Empirical Likelihood ◽  
Missing At Random ◽  
Confidence Regions ◽  
Likelihood Inference ◽  
High Dimensional ◽  
Finite Sample ◽  
The Mean ◽  
Data Missing ◽  
Consistency And Asymptotic Normality ◽  
The Impact

We extend the mean empirical likelihood inference for response mean with data missing at random. The empirical likelihood ratio confidence regions are poor when the response is missing at random, especially when the covariate is high-dimensional and the sample size is small. Hence, we develop three bias-corrected mean empirical likelihood approaches to obtain efficient inference for response mean. As to three bias-corrected estimating equations, we get a new set by producing a pairwise-mean dataset. The method can increase the size of the sample for estimation and reduce the impact of the dimensional curse. Consistency and asymptotic normality of the maximum mean empirical likelihood estimators are established. The finite sample performance of the proposed estimators is presented through simulation, and an application to the Boston Housing dataset is shown.

scholarly journals Onchocerciasis control in Ghana (1974–2016)

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Nana-Kwadwo Biritwum ◽  
Dziedzom K. de Souza ◽  
Odame Asiedu ◽  
Benjamin Marfo ◽  
Uche Veronica Amazigo ◽  
...  
Keyword(s):  
Confidence Interval ◽  
Vector Control ◽  
Control Strategy ◽  
Financial Support ◽  
Control Programme ◽  
Ivermectin Treatment ◽  
Mobile Community ◽  
The Mean ◽  
The Impact ◽  
Onchocerciasis Control

Abstract Background The control of onchocerciasis in Ghana started in 1974 under the auspices of the Onchocerciasis Control Programme (OCP). Between 1974 and 2002, a combination of approaches including vector control, mobile community ivermectin treatment, and community-directed treatment with ivermectin (CDTI) were employed. From 1997, CDTI became the main control strategy employed by the Ghana OCP (GOCP). This review was undertaken to assess the impact of the control interventions on onchocerciasis in Ghana between 1974 and 2016, since which time the focus has changed from control to elimination. Methods In this paper, we review programme data from 1974 to 2016 to assess the impact of control activities on prevalence indicators of onchocerciasis. This review includes an evaluation of CDTI implementation, microfilaria (Mf) prevalence assessments and rapid epidemiological mapping of onchocerciasis results. Results This review indicates that the control of onchocerciasis in Ghana has been very successful, with a significant decrease in the prevalence of infection from 69.13% [95% confidence interval) CI 60.24–78.01] in 1975 to 0.72% (95% CI 0.19–1.26) in 2015. Similarly, the mean community Mf load decreased from 14.48 MF/skin snip in 1975 to 0.07 MF/skin snip (95% CI 0.00–0.19) in 2015. Between 1997 and 2016, the therapeutic coverage increased from 58.50 to 83.80%, with nearly 100 million ivermectin tablets distributed. Conclusions Despite the significant reduction in the prevalence of onchocerciasis in Ghana, there are still communities with MF prevalence above 1%. As the focus of the GOCP has changed from the control of onchocerciasis to its elimination, both guidance and financial support are required to ensure that the latter goal is met.

scholarly journals 996. The Potential for Reducing Opioid and Analgesic Prescriptions Via Herpes Zoster Vaccination

2020 ◽  
Vol 7 (Supplement_1) ◽  
pp. S527-S527
Author(s):  
Jean-Etienne Poirrier ◽  
Justin Carrico ◽  
Jessica K DeMartino ◽  
Katherine A Hicks ◽  
Jeffrey J Stoddard ◽  
...  
Keyword(s):  
Herpes Zoster ◽  
Age Group ◽  
Opioid Prescription ◽  
Varicella Zoster ◽  
Effectiveness Model ◽  
Prescription Rates ◽  
Medication Exposure ◽  
The Mean ◽  
The Impact ◽  
Analgesic Use

Abstract Background Herpes zoster (HZ), or shingles, is a common neurocutaneous disease caused by the reactivation of latent varicella zoster virus that often includes rash and neuropathic pain that may last for months. Opioids and other analgesics may be prescribed. Recombinant zoster vaccine (RZV) is preferentially recommended for the prevention of HZ in adults aged 50 years and older. This study aimed to assess the impact of RZV vaccination on opioid and other analgesic prescription-related outcomes. Methods Estimates of analgesic prescription rates (opioids, benzodiazepines, and other analgesics) among HZ cases were established using Truven claims data from 2012-2018 for adults aged 50 years and older. HZ case avoidance with RZV vaccination was calculated using a previously published cost-effectiveness model. This data was included in a calculator assessing the impact of RZV vaccination on analgesic prescription-related outcomes (compared to no vaccination). Results Between 24.4% and 28.0% of HZ cases in the observed claims had at least one opioid prescription, dependent on age group (4.5%-6.5% and 8.6%-19.6% for benzodiazepines and other analgesics, respectively). The mean number of opioid prescriptions per person in each age group with at least one opioid prescription was between 1.7 and 1.9 (1.7-2.3 and 1.7-2.0 prescriptions for benzodiazepines and other analgesics, respectively). Assuming a 1-million-person population and 65% RZV coverage, the calculator predicts RZV vaccination will prevent 75,002 cases of HZ and will prevent 19,311 people from being prescribed at least 1 HZ-related opioid, 4,502 people from being prescribed benzodiazepines, and 12,201 people from being prescribed other analgesics. Additionally, 34,520 HZ-related opioid prescriptions will be avoided (9,413 benzodiazepine prescriptions; 22,406 other analgesic prescriptions). Conclusion HZ is associated with high levels of opioid, benzodiazepine, and other analgesic use. Primary prevention of HZ by vaccination could potentially reduce opioid and other medication exposure. Disclosures Jean-Etienne Poirrier, PhD, MBA, The GSK group of companies (Employee, Shareholder) Justin Carrico, BS, GlaxoSmithKline (Consultant) Jessica K. DeMartino, PhD, The GlaxoSmithKline group of companies (Employee, Shareholder) Katherine A. Hicks, MS, BSPH, GlaxoSmithKline (Scientific Research Study Investigator, GSK pays my company for my contractual services.) Saurabh P. Nagar, MS, RTI Health Solutions (Employee) Juliana Meyers, MA, GlaxoSmithKline (Other Financial or Material Support, This study was funded by GlaxoSmithKline.)

scholarly journals The Impact of Game-Based, Modeling, and Collaborative Learning Methods on the Achievements, Motivations, and Visual Mathematical Literacy Perceptions

SAGE Open ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 215824402110035
Author(s):  
Aziz İlhan
Keyword(s):  
Collaborative Learning ◽  
Control Group ◽  
Conventional Instruction ◽  
Game Based Learning ◽  
Mathematical Literacy ◽  
Learning Methods ◽  
Learning Groups ◽  
The Mean ◽  
The Impact ◽  
Experimental Group

The present study aimed to investigate the effects of geometry instruction activities conducted in nature based on modeling, game-based, and cooperative learning methods on achievement, mathematical motivation, and visual mathematical literacy perceptions of third-grade elementary school students. The present study is a quantitative study conducted with a pre-test/post-test experimental design with a control group. The study was conducted with 61 students (35 students in the experimental group and 26 students in the control group). Modeling-, game-, and collaborative learning-based activities were conducted with the students in the experimental group. It was determined that the achievements of students who were instructed with modeling-based activities in geometry were high when compared to that of the students instructed with collaborative learning- and game-based methods, and those in the control group where no intervention was applied. This group was followed by the game-based and collaborative learning groups. Based on the variable of motivation, the mean motivation of the students in the modeling group was higher when compared to that of the students in the collaborative learning, game-based, and conventional instruction groups. This group was followed by the collaborative and game-based learning groups. Also, based on the visual mathematical literacy perception variable, the mean visual mathematics literacy perception of the students in the collaborative learning group was higher when compared to that of the students in the groups where the modeling, game-based, and conventional instruction methods were used. This group was followed by the modeling and game-based learning groups.

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