The generation of Langmuir circulations by an instability mechanism

1977 ◽  
Vol 81 (2) ◽  
pp. 209-223 ◽  
Author(s):  
A. D. D. Craik
Keyword(s):  
Continuous Wave ◽  
Current System ◽  
Plane Waves ◽  
Wave Spectrum ◽  
Stokes Drift ◽  
Instability Mechanism ◽  
Fluid Layers ◽  
The Mean ◽  
Langmuir Cells ◽  
Relationship Of

Equations governing the current system in the upper layers of oceans and lakes were derived by Craik & Leibovich (1976). These incorporate the dominant effects of both wind and waves. Solutions comprising the mean wind-driven current and a system of ‘Langmuir’ cells aligned parallel to the wind were found for cases in which the wave field consisted of just a pair of plane waves. However, it was not clear that such cellular motions would persist for the more realistic case of a continuous wave spectrum.The present paper shows that, in the latter case, infinitesimal spanwise periodic perturbations will grow on account of an instability mechanism. Mathematically, the instability is closely similar to the onset of thermal convection in horizontal fluid layers. Physically, the mechanism is governed by kinematical processes involving the mean (Eulerian) wind-driven current and the (Lagrangian) Stokes drift associated with the waves. The relationship of this mechanism to instability models of Garrett and Gammelsrød is clarified.

scholarly journals Reconstruction of Diffusion Coefficients and Power Exponents from Single Lagrangian Trajectories

Fluids ◽  
2021 ◽  
Vol 6 (3) ◽  
pp. 111
Author(s):  
Leonid M. Ivanov ◽  
Collins A. Collins ◽  
Tetyana Margolina
Keyword(s):  
Black Sea ◽  
Diffusion Coefficients ◽  
Current System ◽  
Mean Square Displacement ◽  
California Current ◽  
The Black Sea ◽  
Mean Square ◽  
California Current System ◽  
The Mean ◽  
Non Gaussian

Using discrete wavelets, a novel technique is developed to estimate turbulent diffusion coefficients and power exponents from single Lagrangian particle trajectories. The technique differs from the classical approach (Davis (1991)’s technique) because averaging over a statistical ensemble of the mean square displacement (<X2>) is replaced by averaging along a single Lagrangian trajectory X(t) = {X(t), Y(t)}. Metzler et al. (2014) have demonstrated that for an ergodic (for example, normal diffusion) flow, the mean square displacement is <X2> = limT→∞τX2(T,s), where τX2 (T, s) = 1/(T − s) ∫0T−s(X(t+Δt) − X(t))2 dt, T and s are observational and lag times but for weak non-ergodic (such as super-diffusion and sub-diffusion) flows <X2> = limT→∞≪τX2(T,s)≫, where ≪…≫ is some additional averaging. Numerical calculations for surface drifters in the Black Sea and isobaric RAFOS floats deployed at mid depths in the California Current system demonstrated that the reconstructed diffusion coefficients were smaller than those calculated by Davis (1991)’s technique. This difference is caused by the choice of the Lagrangian mean. The technique proposed here is applied to the analysis of Lagrangian motions in the Black Sea (horizontal diffusion coefficients varied from 105 to 106 cm2/s) and for the sub-diffusion of two RAFOS floats in the California Current system where power exponents varied from 0.65 to 0.72. RAFOS float motions were found to be strongly non-ergodic and non-Gaussian.

Intra-Task Reliability and Specificity of Individual Consistency

1970 ◽  
Vol 30 (2) ◽  
pp. 583-587 ◽  
Author(s):  
Albert V. Carron
Keyword(s):  
Motor Response ◽  
Present Report ◽  
Motor Task ◽  
Response Component ◽  
Linear Movement ◽  
The Mean ◽  
Individual Consistency ◽  
Response Consistency ◽  
Relationship Of ◽  
The Relationship

The present report is based on reanalysis of data of Marisi (1969) in order to examine the relationship of consistency of motor response among the component responses of a single motor task. 120 high school Ss were tested on a special task, the rho. A single trial on this motor task can be logically separated into three component motor responses: reaction time, a short circular movement, and a short linear movement. The results indicated that consistency of motor response was moderately reliable within the response components but tended to be response-component specific. Further, both the reliability and specificity of motor-response consistency were independent of the size of the mean performance scores.

Early results of micropulse transscleral cyclophotocoagulation for the treatment of glaucoma

2019 ◽  
Vol 30 (4) ◽  
pp. 700-705 ◽  
Author(s):  
Alexander T Nguyen ◽  
Jessica Maslin ◽  
Robert J Noecker
Keyword(s):  
Intraocular Pressure ◽  
Continuous Wave ◽  
Open Angle Glaucoma ◽  
Case Series ◽  
Angle Closure ◽  
Secondary Outcome ◽  
Early Results ◽  
Pressure Lowering ◽  
Transscleral Cyclophotocoagulation ◽  
The Mean

Purpose: To describe our clinical experience with the efficacy and safety of micropulse transscleral cyclophotocoagulation as a treatment for glaucoma. Methods: In this retrospective case series, we reviewed the charts of 95 consecutive patients with various glaucoma subtypes who underwent micropulse transscleral cyclophotocoagulation. Patients were offered micropulse transscleral cyclophotocoagulation if they had perimetric glaucoma refractory to intraocular pressure–lowering topical medications and who were poor candidates for traditional filtering surgery. Eligible patients were treated with the Micropulse P3 device (IQ 810 Laser Systems; Iridex, Mountain View, CA, USA) at 2.0–2.5 W for a duration of 90 s per hemisphere at a 31.3% duty cycle. If a retreatment was needed, the power was increased to up to 3.0 W with other parameters remaining the same. Patients were considered successfully treated if their intraocular pressure was lowered by at least 20% compared to their baseline. The main outcome measure was post-operative intraocular pressure; secondary outcome measures included the number of adverse events and complications that occurred with treatment. Results: The glaucoma subtypes treated included primary open-angle glaucoma (n = 51), exfoliation glaucoma (n = 24), chronic angle-closure glaucoma (n = 15), and congenital/juvenile glaucoma (n = 5). The mean pre-operative intraocular pressure was 25.1 ± 5.3 mm Hg and the mean post-operative intraocular pressure at 12 months was 17.5 ± 5.1 mm Hg (p = 0.004). The mean number of intraocular pressure–lowering medications used preoperatively was 3.0 ± 1.1; the mean number of medications used at the 12-month post-operative visit was 1.4 ± 1.0 (p = 0.03). Success with one treatment was achieved in 73 (76.8%) of patients. With multiple treatments, all patients had significant intraocular pressure–lowering compared to baseline. The maximum number of treatments received by any single patient was 5. There were no instances of prolonged intraocular inflammation or long-term hypotony. Conclusion: Micropulse transscleral cyclophotocoagulation appears to be a safe and efficacious treatment for glaucoma. Given its improved safety profile compared to continuous-wave transscleral cyclophotocoagulation, it deserves consideration as a primary procedure.

Relationship of Spiritual well-being and emotional intelligence among Iranian' nursing students

2021 ◽  
Vol 15 (6) ◽  
pp. 1634-1640
Author(s):  
Javad Jafari ◽  
Asra Nassehi ◽  
Mohammadali Zareez ◽  
Seydamalek Dadkhah ◽  
Najmeh Saberi ◽  
...  
Keyword(s):  
Emotional Intelligence ◽  
Nursing Students ◽  
Pearson Correlation ◽  
Well Being ◽  
Self Awareness ◽  
Spiritual Well Being ◽  
The Mean ◽  
High Level ◽  
Relationship Of ◽  
Religious Wellbeing

Background: Among all aspects of nursing care, the spiritual one is the issue that has received little attention. Having spiritual wellbeing (SWB) is a necessity to provide appropriate spiritual care. In addition to, the Emotional intelligence (EI) is one of the most important factors in social and professional success and is essential for effective nursing practice. Therefore, aim of study was evaluating the Relationship between SWB and EI among nursing students. Methods: The sample of this descriptive-analytic study consisted of 136 nursing students studying at Bam University of Medical Sciences selected by convenience sampling method. The Bradberry and Greaves 28-item EI scale, Palutzian and Ellison SWB Scale were used to assess the total score of EI and SWB. Collected data were analyzed using descriptive statistics (mean and standard deviation), Pearson correlation coefficient, independent t-test and one-way ANOVA with SPSS v18. Results: The mean score of SWB and EI were 97.1±11.56 and 123.4 + 123.6, respectively. The mean score dimensions of SWB include (religious wellbeing 47.9±6.6, existential wellbeing 49.1±5.7) and dimensions EI: self-awareness, self-management, social awareness, and relationship management were 27.2 3 3.2, 36.2 2 5.4, 25.1 + 3.5 and 35.1 + 4.5, respectively. The majority of students have reported moderate level SWB and high level of emotional intelligence. The factors influencing their level of SWB were academic semester and age (p<0.05). Conclusion: Although the level of students' EI and SWB were at a desirable level in this study, due to the nature of nursing and the interaction between nurses and patients, providing a suitable learning environment for the development of EI is essential. Therefore, it is suggested that nursing policymakers should develop appropriate educational programs for nurses and provide curriculum for students to promote their knowledge and skills. Keywords: spiritual, religious, wellbeing, existential, nursing, emotional intelligence

DNA barcoding and phylogenetic relationship of shrimps (Crustacea: Decapoda) of Bangladesh

2021 ◽  
Vol 7 (1) ◽  
pp. 941-946
Author(s):  
Md Sagir Ahmed ◽  
Sumaiya Salam ◽  
Sayeda Sabrina Sarwar Rumana ◽  
Anindita Barua
Keyword(s):  
Dna Barcoding ◽  
Genetic Divergence ◽  
New Records ◽  
Coi Gene ◽  
Identification System ◽  
Taxonomic Rank ◽  
Macrobrachium Nipponense ◽  
Shrimp Species ◽  
The Mean ◽  
Relationship Of

We adopted DNA barcoding technique using a 658-bp fragment of the mitochondrial cytochrome c oxidase I (COI) gene to identify shrimp species collected from the different areas of Bangladesh. A total of 24 sequences were generated belonging to 14 species including four new records- Macrobrachium nipponense, Macrobrachium kistnense, Exopalaemon carinicauda and Alpheus malleator. Genetic distance measured with Kimura 2 parameter showed that genetic divergence increased with higher taxonomic rank. The mean genetic divergence was evaluated and found to be 0.935%, 22.67% and 30.92% within species, genus and family, respectively. In addition to the barcode-based species identification system, phylogenetic relationships were established where individuals belonging to the same species were grouped under the same clade. Maximum likelihood (ML) was preferred as the statistical method and as expected, the phylogenetic tree complemented and ensured the conventional taxonomy. The present study evidently showed that DNA barcoding can be served as an effective tool to discriminate the shrimp species and this will enhance the understanding on evolution and conservation biology. Bioresearch Commu. 7(1): 941-946, 2021 (January)

Association of Hemoglobin A1C With TDP-43 Pathology in Community-Based Elders

Neurology ◽  
2021 ◽  
pp. 10.1212/WNL.0000000000012025
Author(s):  
Shahram Oveisgharan ◽  
Ana W. Capuano ◽  
Sukriti Nag ◽  
Sonal Agrawal ◽  
Lisa L. Barnes ◽  
...  
Keyword(s):  
Severity Score ◽  
Hemoglobin A1c ◽  
Oldest Old ◽  
Brain Regions ◽  
Inverse Association ◽  
Community Based ◽  
Cytoplasmic Inclusions ◽  
The Mean ◽  
High Level ◽  
Relationship Of

Objective.We tested the hypothesis that an inverse association exists between diabetes mellitus (DM) and hemoglobin A1C (A1C) with Transactive response DNA binding protein 43 (TDP-43) levels in older adults.Methods.We leveraged antemortem and postmortem data of decedents from three community-based clinical-pathological studies. DM status, A1C levels, and medications for DM were documented annually. TDP-43 cytoplasmic inclusions, evaluated in 6 brain regions using immunohistochemistry, were used to obtain a semiquantitative TDP-43 score (0-5) in each region, and scores were averaged across regions to obtain a TDP-43 severity score. We used linear regressions to test the association of DM and A1C with the TDP-43 severity score.Results.On average, participants (n=817) were 90 years old at the time of death, three fourth were women, and one fourth had DM. The mean A1C was 6.0% (SD=0.6). TDP-43 was observed in 54% of participants, and the mean TDP-43 score was 0.7 (range 0-4.5). A higher level of A1C was associated with a lower TDP-43 score (estimate=-0.156, S.E.=0.060, p=0.009) while DM had a borderline inverse association with the TDP-43 score (estimate=-0.163, S.E.=0.087, p=0.060). The association of higher levels of A1C with lower TDP-43 scores persisted after further adjustment by Apolipoprotein ε4, vascular risk factors, stroke, and hypoglycemic medications. Exclusion of the oldest old participants did not change the results.Conclusion.Overall, the results suggest that a high level of A1C is associated with less TDP-43 proteinopathy in older persons while the relationship of DM with TDP-43 needs further study.

Respiratory Periodicity and Electroencephalogram Arousals During Sleep in Older Adults

2007 ◽  
Vol 8 (4) ◽  
pp. 249-260 ◽  
Author(s):  
Barbara Waag Carlson ◽  
Virginia J. Neelon ◽  
John R. Carlson ◽  
Marilyn Hartman ◽  
Sunil Dogra
Keyword(s):  
Older Adults ◽  
Exploratory Study ◽  
High Variability ◽  
Arterial Oxygenation ◽  
Type B ◽  
Breathing Patterns ◽  
The Mean ◽  
Relationship Of ◽  
The Relationship ◽  
Electroencephalogram Eeg

The aim of this exploratory study was to examine the relationship of electroencephalogram (EEG) arousals to breathing patterns and the relationship of both arousals and breathing patterns to arterial oxygenation during sleep in older adults. Five older adults were monitored using standard polysomnography. Records were divided into 5-min segments and breathing patterns identified based on the level of respiratory periodicity and the variability in the frequency of breathing cycles. Standard criteria were used to determine sleep states and occurrence of EEG arousals. High respiratory periodicity was seen in 23% of the segments, whereas 24% had low respiratory periodicity with minimal variability in the frequency of breathing (Type A low respiratory periodicity) and 53% had low respiratory periodicity with high variability in the frequency of breathing (Type B low respiratory periodicity). Nearly all (97%) segments with high respiratory periodicity had EEG arousals, whereas fewer segments (33%) with low respiratory periodicity had arousals, regardless of the stage of sleep. Desaturations occurred more often in segments with high respiratory periodicity, F (2,4) = 57.3, p < .001, but overall, the mean SaO2 of segments with high respiratory periodicity did not differ from levels seen in segments with low respiratory periodicity, F( 2,4) = 0.77, ns. Our findings suggest that high respiratory periodicity is a common feature of EEG arousals and, in older adults, may be important for maintaining oxygen levels during desaturations during sleep.

scholarly journals Relationship of altitude mountain sickness and smoking: a Catalan traveller’s cohort study

BMJ Open ◽  
2017 ◽  
Vol 7 (9) ◽  
pp. e017058 ◽  
Author(s):  
Alba Sánchez-Mascuñano ◽  
Cristina Masuet-Aumatell ◽  
Sergio Morchón-Ramos ◽  
Josep M Ramon
Keyword(s):  
Smoking Status ◽  
Medical Advice ◽  
Health Clinic ◽  
Travel Health ◽  
Systemic Corticosteroids ◽  
The Mean ◽  
Mountain Sickness ◽  
Relationship Of ◽  
The Relationship ◽  
Chronic Use

ObjectivesThe aim of this study is to analyse the relationship between smoking andaltitude mountain sicknessin a cohort of travellers to 2500 metres above sea level (masl) or higher.SettingTravel Health Clinic at the Hospital Universitari de Bellvitge, in Barcelona, Spain.ParticipantsA total of 302 adults seeking medical advice at the travel clinic, between July 2012 and August 2014, before travelling to 2500 masl or above, who agreed to participate in the study and to be contacted after the trip were included. Individuals who met the following criteria were excluded: younger than 18 years old, taking carbonic anhydrase inhibitors for chronic use, undergoing treatment with systemic corticosteroids and taking any medication that might prevent or treat altitude mountain sickness (AMS) prior to or during the trip. The majority of participants were women (n=156, 51.7%). The mean age was 37.7 years (SD 12.3). The studied cohort included 74 smokers (24.5%), 158 (52.3%) non-smokers and 70 (23.2%) ex-smokers. No statistical differences were observed between different sociodemographic characteristics, constitutional symptoms or drug use and smoking status.OutcomesThe main outcome was the development of AMS, which was defined according to the Lake Louise AMS criteria.ResultsAMS, according to the Lake Louise score, was significantly lower in smokers; the value was 14.9%, 95% CI (6.8 to 23.0%) in smokers and 29.4%, 95% CI (23.5 to 35.3%) in non-smokers with an adjusted OR of 0.54, 95% CI (0.31 to 0.97) independent of gender, age and maximum altitude reached.ConclusionsThese results suggest that smoking could reduce the risk of AMS in non-acclimated individuals. Further studies should be performed in larger cohorts of travellers to confirm these results. Despite the results, smoking must be strongly discouraged because it greatly increases the risk of cardiorespiratory diseases, cancer and other diseases.

scholarly journals On the Wave Spectrum Generated by Tropical Heating

2011 ◽  
Vol 68 (9) ◽  
pp. 2042-2060 ◽  
Author(s):  
David A. Ortland ◽  
M. Joan Alexander ◽  
Alison W. Grimsdell
Keyword(s):  
Linear Models ◽  
Nonlinear Models ◽  
Wave Spectrum ◽  
Convective Heating ◽  
Temperature Structure ◽  
Mean Flow ◽  
Quasi Biennial Oscillation ◽  
Wave Response ◽  
Zonal Wavenumber ◽  
The Mean

Abstract Convective heating profiles are computed from one month of rainfall rate and cloud-top height measurements using global Tropical Rainfall Measuring Mission and infrared cloud-top products. Estimates of the tropical wave response to this heating and the mean flow forcing by the waves are calculated using linear and nonlinear models. With a spectral resolution up to zonal wavenumber 80 and frequency up to 4 cpd, the model produces 50%–70% of the zonal wind acceleration required to drive a quasi-biennial oscillation (QBO). The sensitivity of the wave spectrum to the assumed shape of the heating profile, to the mean wind and temperature structure of the tropical troposphere, and to the type of model used is also examined. The redness of the heating spectrum implies that the heating strongly projects onto Hough modes with small equivalent depth. Nonlinear models produce wave flux significantly smaller than linear models due to what appear to be dynamical processes that limit the wave amplitude. Both nonlinearity and mean winds in the lower stratosphere are effective in reducing the Rossby wave response to heating relative to the response in a linear model for a mean state at rest.

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