scholarly journals Formulation and solution of a generalized Chebyshev problem. II

2020 ◽  
Vol 65 (4) ◽  
pp. 714-733
Author(s):  
Mikhail P. Yushkov ◽  
Keyword(s):  
Boundary Value Problem ◽  
Mechanical System ◽  
Control Force ◽  
Short Term ◽  
Holonomic Constraint ◽  
Holonomic Systems ◽  
Order Constraints ◽  
Chebyshev Problem ◽  
State Of Rest

This work is a continuation of the article “Formulation and solution of a generalized Chebyshev problem. I”, in which a generalized Chebyshev problem was formulated, two theories of motion for non-holonomic systems with high-order constraints were presented for its solution. These theories were used to study the motion of the Earth’s satellite when fixing the magnitude of its acceleration (this was equivalent to imposing a linear non-holonomic constraint of the third order). In the offered article, the second theory, based on the application of the generalized Gauss principle, is used to solve one of the most important problems of control theory: finding the optimal control force that translates a mechanical system with a finite number of degrees of freedom from one phase state to another in a specified time. The application of the theory is demonstrated by solving a model problem of controlling the horizontal motion of a cart bearing the axes of s mathematical pendulums. Initially, the problem is solved by applying the Pontryagin maximum principle, which minimizes the functional of the square of the desired horizontal control force, which transfers the mechanical system from a state of rest to a new state of rest in the specified time with the horizontal displacement of the cart by S (that is, the problem of vibration damping is considered). Let’s call this approach the first method of solving the control problem. It is shown that a linear non-holonomic constraint of the order (2s + 4) is continuously performed. This suggests applying the second theory of motion for non-holonomic systems with high-order constraints to the same problem (see the previous article), developed at the Department of Theoretical and Applied Mechanics of the Faculty of Mathematics and Mechanics of Saint Petersburg State University. Let’s call this approach the second method of solving the problem. Calculations performed for the case of s = 2 showed that the results obtained by the both methods are practically the same for a short-term motion of the system, while they differ sharply for a long-term motion. This is because the control found using the first method contains harmonics with the system’s natural frequencies, which tends to bring the system into resonance. With a short-term motion, this is not noticeable, and with a long-term motion, there are large fluctuations in the system. In contrast, when using the second method, the control is in the form of a polynomial in time, which provides a relatively smooth motion of the system. In addition, in order to eliminate the control force jumps at the beginning and end of the motion, we propose to solve a generalized boundary value problem and discuss some special cases that sometimes occur when using the second method for solving the boundary value problem.

Conceptual short-term memory (CSTM) supports core claims of Christiansen and Chater

2016 ◽  
Vol 39 ◽  
Author(s):  
Mary C. Potter
Keyword(s):  
Working Memory ◽  
Rapid Serial Visual Presentation ◽  
Language Comprehension ◽  
Short Term Memory ◽  
Visual Presentation ◽  
Long Term Memory ◽  
Short Term ◽  
Term Memory ◽  
Use Of Knowledge

AbstractRapid serial visual presentation (RSVP) of words or pictured scenes provides evidence for a large-capacity conceptual short-term memory (CSTM) that momentarily provides rich associated material from long-term memory, permitting rapid chunking (Potter 1993; 2009; 2012). In perception of scenes as well as language comprehension, we make use of knowledge that briefly exceeds the supposed limits of working memory.

Ultrastructural investigations of MDL 19,660-induced effects on the canine platelet and megakaryocyte

1990 ◽  
Vol 48 (3) ◽  
pp. 374-375
Author(s):  
D.E. Loudy ◽  
J. Sprinkle-Cavallo ◽  
J.T. Yarrington ◽  
F.Y. Thompson ◽  
J.P. Gibson
Keyword(s):  
Antidepressant Drug ◽  
Beagle Dogs ◽  
Long Term Effects ◽  
Short Term ◽  
Platelet Counts ◽  
Toxicological Studies ◽  
Induced Aggregation ◽  
Internal Architecture

Previous short term toxicological studies of one to two weeks duration have demonstrated that MDL 19,660 (5-(4-chlorophenyl)-2,4-dihydro-2,4-dimethyl-3Hl, 2,4-triazole-3-thione), an antidepressant drug, causes a dose-related thrombocytopenia in dogs. Platelet counts started to decline after two days of dosing with 30 mg/kg/day and continued to decrease to their lowest levels by 5-7 days. The loss in platelets was primarily of the small discoid subpopulation. In vitro studies have also indicated that MDL 19,660: does not spontaneously aggregate canine platelets and has moderate antiaggregating properties by inhibiting ADP-induced aggregation. The objectives of the present investigation of MDL 19,660 were to evaluate ultrastructurally long term effects on platelet internal architecture and changes in subpopulations of platelets and megakaryocytes.Nine male and nine female beagle dogs were divided equally into three groups and were administered orally 0, 15, or 30 mg/kg/day of MDL 19,660 for three months. Compared to a control platelet range of 353,000- 452,000/μl, a doserelated thrombocytopenia reached a maximum severity of an average of 135,000/μl for the 15 mg/kg/day dogs after two weeks and 81,000/μl for the 30 mg/kg/day dogs after one week.

Comparison of Auditory, Language, Memory, and Attention Abilities in Children With and Without Listening Difficulties

2020 ◽  
Vol 29 (4) ◽  
pp. 710-727
Author(s):  
Beula M. Magimairaj ◽  
Naveen K. Nagaraj ◽  
Alexander V. Sergeev ◽  
Natalie J. Benafield
Keyword(s):  
Auditory Processing ◽  
Short Term Memory ◽  
Group Differences ◽  
Long Term Memory ◽  
Short Term ◽  
Significant Group ◽  
Term Memory ◽  
Memory And Attention ◽  
Speed And Accuracy

Objectives School-age children with and without parent-reported listening difficulties (LiD) were compared on auditory processing, language, memory, and attention abilities. The objective was to extend what is known so far in the literature about children with LiD by using multiple measures and selective novel measures across the above areas. Design Twenty-six children who were reported by their parents as having LiD and 26 age-matched typically developing children completed clinical tests of auditory processing and multiple measures of language, attention, and memory. All children had normal-range pure-tone hearing thresholds bilaterally. Group differences were examined. Results In addition to significantly poorer speech-perception-in-noise scores, children with LiD had reduced speed and accuracy of word retrieval from long-term memory, poorer short-term memory, sentence recall, and inferencing ability. Statistically significant group differences were of moderate effect size; however, standard test scores of children with LiD were not clinically poor. No statistically significant group differences were observed in attention, working memory capacity, vocabulary, and nonverbal IQ. Conclusions Mild signal-to-noise ratio loss, as reflected by the group mean of children with LiD, supported the children's functional listening problems. In addition, children's relative weakness in select areas of language performance, short-term memory, and long-term memory lexical retrieval speed and accuracy added to previous research on evidence-based areas that need to be evaluated in children with LiD who almost always have heterogenous profiles. Importantly, the functional difficulties faced by children with LiD in relation to their test results indicated, to some extent, that commonly used assessments may not be adequately capturing the children's listening challenges. Supplemental Material https://doi.org/10.23641/asha.12808607

Abstract #283 Diabetes Increases Short-Term but not Long-Term Risk of Fracture: A Community-Based Study

2019 ◽  
Vol 25 ◽  
pp. 114
Author(s):  
Alyssa Dufour ◽  
Setareh Williams ◽  
Richard Weiss ◽  
Elizabeth Samelson
Keyword(s):  
Short Term ◽  
Community Based ◽  
Risk Of Fracture

Abstract #238: Improved Short Term and Long Term Outcomes of Early Insulin Initiation in Type 2 Diabetes Over 10 Years

2017 ◽  
Vol 23 ◽  
pp. 50
Author(s):  
Jothydev Kesavadev ◽  
Shashank Joshi ◽  
Banshi Saboo ◽  
Hemant Thacker ◽  
Arun Shankar ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Insulin Initiation ◽  
Long Term Outcomes ◽  
Short Term

Anticoagulation in addition to dual antiplatelet therapy has no impact on long-term follow-up after endovascular treatment of (sub)acute lower limb ischemia

VASA ◽  
2019 ◽  
Vol 48 (4) ◽  
pp. 321-329
Author(s):  
Mariya Kronlage ◽  
Erwin Blessing ◽  
Oliver J. Müller ◽  
Britta Heilmeier ◽  
Hugo A. Katus ◽  
...  
Keyword(s):  
Endovascular Treatment ◽  
Antiplatelet Therapy ◽  
Dual Antiplatelet Therapy ◽  
Limb Ischemia ◽  
Bleeding Complications ◽  
Severe Bleeding ◽  
Short Term ◽  
Long Term Follow Up

Summary. Background: To assess the impact of short- vs. long-term anticoagulation in addition to standard dual antiplatelet therapy (DAPT) upon endovascular treatment of (sub)acute thrombembolic occlusions of the lower extremity. Patient and methods: Retrospective analysis was conducted on 202 patients with a thrombembolic occlusion of lower extremities, followed by crirical limb ischemia that received endovascular treatment including thrombolysis, mechanical thrombectomy, or a combination of both between 2006 and 2015 at a single center. Following antithrombotic regimes were compared: 1) dual antiplatelet therapy, DAPT for 4 weeks (aspirin 100 mg/d and clopidogrel 75 mg/d) upon intervention, followed by a lifelong single antiplatelet therapy; 2) DAPT plus short term anticoagulation for 4 weeks, followed by a lifelong single antiplatelet therapy; 3) DAPT plus long term anticoagulation for > 4 weeks, followed by a lifelong anticoagulation. Results: Endovascular treatment was associated with high immediate revascularization (> 98 %), as well as overall and amputation-free survival rates (> 85 %), independent from the chosen anticoagulation regime in a two-year follow up, p > 0.05. Anticoagulation in addition to standard antiplatelet therapy had no significant effect on patency or freedom from target lesion revascularization (TLR) 24 months upon index procedure for both thrombotic and embolic occlusions. Severe bleeding complications occurred more often in the long-term anticoagulation group (9.3 % vs. 5.6 % (short-term group) and 6.5 % (DAPT group), p > 0.05). Conclusions: Our observational study demonstrates that the choice of an antithrombotic regime had no impact on the long-term follow-up after endovascular treatment of acute thrombembolic limb ischemia whereas prolonged anticoagulation was associated with a nominal increase in severe bleeding complications.

Intraindividual Variability and Stability of Affect and Well-Being

GeroPsych ◽  
2013 ◽  
Vol 26 (3) ◽  
pp. 185-199 ◽  
Author(s):  
Christina Röcke ◽  
Annette Brose
Keyword(s):  
Age Differences ◽  
Well Being ◽  
Subjective Well Being ◽  
Emotional Experiences ◽  
Short Term ◽  
Regulatory Processes ◽  
Functional Implications ◽  
Methodological Approaches ◽  
Underlying Processes

Whereas subjective well-being remains relatively stable across adulthood, emotional experiences show remarkable short-term variability, with younger and older adults differing in both amount and correlates. Repeatedly assessed affect data captures both the dynamics and stability as well as stabilization that may indicate emotion-regulatory processes. The article reviews (1) research approaches to intraindividual affect variability, (2) functional implications of affect variability, and (3) age differences in affect variability. Based on this review, we discuss how the broader literature on emotional aging can be better integrated with theories and concepts of intraindividual affect variability by using appropriate methodological approaches. Finally, we show how a better understanding of affect variability and its underlying processes could contribute to the long-term stabilization of well-being in old age.

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