A Novel Connectionist Network for Solving Long Time-Lag Prediction Tasks

2009 ◽  
pp. 557-566
Author(s):  
Keith Johnson ◽  
Cara MacNish
Keyword(s):  
Time Lag ◽  
Connectionist Network ◽  
Long Time

Hopf bifurcation for a discontinuous HTLV-1 model

Filomat ◽  
2017 ◽  
Vol 31 (20) ◽  
pp. 6247-6267 ◽  
Author(s):  
Elham Shamsara ◽  
Zahra Afsharnezhad ◽  
Reihaneh Mostolizadeh
Keyword(s):  
Hopf Bifurcation ◽  
Sliding Mode ◽  
Early Stage ◽  
Time Lag ◽  
Discontinuous System ◽  
Steady State Condition ◽  
Ctl Response ◽  
Optimal Drug ◽  
Long Time ◽  
Immunosuppressive Diseases

Developing accurate mathematical models for host immune response in immunosuppressive diseases such as HIV and HTLV-1 are essential to achieve an optimal drug therapy regime. Since for HTLV-1 specific CTL response typically occurs after a time lag, we consider a discontinuous response function to better describe this lagged response during the early stage of the infectious, thus the system of HTLV-1 model will be a discontinuous system. For analyzing the dynamic of the system we use Filippov theory and find conditions in which the Filippov system undergoes a Hopf bifurcation. The Hopf bifurcation help us to find stable and unstable periodic oscillations and can be used to predict whether the CTL response can return to a steady state condition. Also, Hopf bifurcation in sliding mode is investigated. In this case the solutions will remain in the hyper-surface of discontinuity and as a consequence the disease cannot progress, at least for a long time. Finally we use numerical simulations to demonstrate the results by example.

A “Natural” Proposal for Addressing Climate Change

2014 ◽  
Vol 28 (3) ◽  
pp. 359-363 ◽  
Author(s):  
Thomas E. Lovejoy
Keyword(s):  
Climate Change ◽  
Greenhouse Gases ◽  
Ethical Issues ◽  
Time Lag ◽  
Radiant Heat ◽  
Time Frame ◽  
Future Generations ◽  
Considerable Time ◽  
Long Time

One of the fundamental challenges of climate change is that we contribute to it increment by increment, and experience it increment by increment after a considerable time lag. As a consequence, it is very difficult to see what we are doing to ourselves, to future generations, and to the living planet as a whole. There are monumental ethical issues involved, but they are obscured by the incremental nature of the process and the long time frame before reaching the concentration of greenhouse gases and the ensuing accumulation of radiant heat—and consequent climate change—that ensues.

Downregulation of the vasopressin type 2 receptor after vasopressin-induced internalization: involvement of a lysosomal degradation pathway

2005 ◽  
Vol 288 (6) ◽  
pp. C1390-C1401 ◽  
Author(s):  
Richard Bouley ◽  
Herbert Y. Lin ◽  
Malay K. Raychowdhury ◽  
Vladimir Marshansky ◽  
Dennis Brown ◽  
...  
Keyword(s):  
Cell Surface ◽  
Fluorescent Protein ◽  
Collecting Duct ◽  
Time Lag ◽  
Renal Medulla ◽  
Degradation Pathway ◽  
Urinary Concentration ◽  
Long Time ◽  
Green Fluorescent ◽  
Golgi Network

Vasopressin (VP) increases urinary concentration by signaling through the vasopressin receptor (V2R) in collecting duct principal cells. After downregulation, V2R reappears at the cell surface via an unusually slow (several hours) “recycling” pathway. To examine this pathway, we expressed V2R-green fluorescent protein (GFP) in LLC-PK1a cells. V2R-GFP showed characteristics similar to those of wild-type V2R, including high affinity for VP and adenylyl cyclase stimulation. V2R-GFP was located mainly in the plasma membrane in unstimulated cells, but it colocalized with the lysosomal marker Lysotracker after VP-induced internalization. Western blot analysis of V2R-GFP showed a broad 57- to 68-kDa band and a doublet at 46 and 52 kDa before VP treatment. After 4-h VP exposure, the 57- to 68-kDa band lost 50% of its intensity, whereas the lower 46-kDa band increased by 200%. The lysosomal inhibitor chloroquine abolished this VP effect, whereas lactacystin, a proteasome inhibitor, had no effect. Incubating cells at 20°C to block trafficking from the trans-Golgi network reduced V2R membrane fluorescence, and a perinuclear patch developed. Cycloheximide reduced the intensity of this patch, showing that newly synthesized V2R-GFP contributed significantly to its appearance. Cycloheximide also inhibited the reappearance of cell surface V2R after downregulation. We conclude that after downregulation, V2R-GFP is delivered to lysosomes and degraded. Reappearance of V2R at the cell surface depends on new protein synthesis, partially explaining the long time lag needed to fully reestablish V2R at the cell surface after downregulation. This degradative pathway may be an adaptive response to allow receptor-ligand association in the hypertonic and acidic environment of the renal medulla.

Non-Gaussian probability distributions of solar wind fluctuations

1994 ◽  
Vol 12 (12) ◽  
pp. 1127-1138 ◽  
Author(s):  
E. Marsch ◽  
C. Y. Tu
Keyword(s):  
Solar Wind ◽  
Probability Distributions ◽  
Time Lag ◽  
Small Scale ◽  
Time Lags ◽  
Mhd Turbulence ◽  
Theoretical Concepts ◽  
Fluid Turbulence ◽  
Long Time ◽  
Non Gaussian

Abstract. The probability distributions of field differences ∆x(τ)=x(t+τ)-x(t), where the variable x(t) may denote any solar wind scalar field or vector field component at time t, have been calculated from time series of Helios data obtained in 1976 at heliocentric distances near 0.3 AU. It is found that for comparatively long time lag τ, ranging from a few hours to 1 day, the differences are normally distributed according to a Gaussian. For shorter time lags, of less than ten minutes, significant changes in shape are observed. The distributions are often spikier and narrower than the equivalent Gaussian distribution with the same standard deviation, and they are enhanced for large, reduced for intermediate and enhanced for very small values of ∆x. This result is in accordance with fluid observations and numerical simulations. Hence statistical properties are dominated at small scale τ by large fluctuation amplitudes that are sparsely distributed, which is direct evidence for spatial intermittency of the fluctuations. This is in agreement with results from earlier analyses of the structure functions of ∆x. The non-Gaussian features are differently developed for the various types of fluctuations. The relevance of these observations to the interpretation and understanding of the nature of solar wind magnetohydrodynamic (MHD) turbulence is pointed out, and contact is made with existing theoretical concepts of intermittency in fluid turbulence.

The Vanishing Gradient Problem During Learning Recurrent Neural Nets and Problem Solutions

1998 ◽  
Vol 06 (02) ◽  
pp. 107-116 ◽  
Author(s):  
Sepp Hochreiter
Keyword(s):  
Time Series ◽  
Time Series Prediction ◽  
Time Lag ◽  
Neural Nets ◽  
Alternative Methods ◽  
Reasonable Time ◽  
Practical Applications ◽  
Learning Time ◽  
Long Time ◽  
Gradient Based

Recurrent nets are in principle capable to store past inputs to produce the currently desired output. Because of this property recurrent nets are used in time series prediction and process control. Practical applications involve temporal dependencies spanning many time steps, e.g. between relevant inputs and desired outputs. In this case, however, gradient based learning methods take too much time. The extremely increased learning time arises because the error vanishes as it gets propagated back. In this article the de-caying error flow is theoretically analyzed. Then methods trying to overcome vanishing gradients are briefly discussed. Finally, experiments comparing conventional algorithms and alternative methods are presented. With advanced methods long time lag problems can be solved in reasonable time.

Post-Agreement Negotiations in the Comprehensive Nuclear-Test-Ban Treaty Regime

2013 ◽  
Vol 18 (3) ◽  
pp. 357-378 ◽  
Author(s):  
Mordechai (Moti) Melamud
Keyword(s):  
Time Lag ◽  
Interesting Case ◽  
Nuclear Test ◽  
Political Issues ◽  
Long Time ◽  
Exogenous Factors ◽  
Test Ban ◽  
Nuclear Test Ban ◽  
Test Ban Treaty

AbstractWhen considering the concept of post-agreement negotiations (PAN), the CTBT presents a particularly interesting case, because of its elusive status caused by the unusually long time lag between the treaty’s adoption in 1996 and its still unattained entry into force. For almost two decades, negotiations on key elements have been ongoing in the Preparatory Commission (PrepCom) in preparation for entry-into-force as required by the treaty. This article explores the challenges of PAN in the framework of the PrepCom and its place in the CTBT regime evolution. Using four factors in regime development – adjustment, maintenance, cybernetics and exogenous factors – the work of the PrepCom concerning verification is analyzed. Technical and political issues are described as examples from the PrepCom’s work since the opening of the CTBT for signature illustrating regime building through post agreement negotiations.

The Neural Network Control Algorithm Research of Single Crystal Furnace Temperature System

2013 ◽  
Vol 765-767 ◽  
pp. 789-792
Author(s):  
Xin Song ◽  
Ming Yu Li ◽  
Li Li ◽  
Chao Yang
Keyword(s):  
Neural Network ◽  
Single Crystal ◽  
Control Strategies ◽  
Time Lag ◽  
Adaptive Method ◽  
Network Control ◽  
Temperature Control System ◽  
Neural Network Modeling ◽  
Neural Network Control ◽  
Long Time

Straight pull single crystal furnaces temperature control system has problem of the long time lag and nonlinearity, so the precise mathematic mode that is hard to build. Advanced control strategies show strong advantages for resolving these problems. This paper use artificial neural network modeling approach to establish single crystal furnace temperatures neural network control BP structure model, use adaptive method to control the temperature of the single crystal furnace.

scholarly journals Self-regulation of journalism in Spain

2015 ◽  
pp. 29-35
Author(s):  
A. N. Rylova
Keyword(s):  
Freedom Of Expression ◽  
Time Lag ◽  
Self Regulation ◽  
Professional Community ◽  
The State ◽  
State Control ◽  
Western Countries ◽  
Long Time ◽  
Rules And Principles ◽  
History Of

Self-regulation of journalism resides in voluntary measures taken by the professional community of journalists to guarantee the observation of certain rules and principles in the process of providing information to public, maintain independence and credibility of media. The institution of self-regulation of Spanish journalism emerged later than in other Western countries due to the history of interaction between the State and media: for a long time Spanish media were under State control and freedom of expression was constantly defied. That is why first attempts to establish bodies for self-regulation of journalism in the post-Franco Spain evoked fears of a return to censorship. However, the time lag concerning media self- regulation allowed Spain to use other countries’ experience. Nowadays, the degree of self-regulation of journalism in Spain is similar to that of the Western countries. The institution of self-regulation operates successfully and facilitates Spanish media authority.

scholarly journals Factors Hindering Class Attendance: Views of University Accounting Students

2020 ◽  
Vol 12 (1) ◽  
pp. 86
Author(s):  
Lillian Wally-Dima ◽  
Christian John Mbekomize ◽  
Alicia Nametsegang
Keyword(s):  
Time Management ◽  
Proper Time ◽  
Time Lag ◽  
Accounting Students ◽  
Tertiary Institutions ◽  
Class Attendance ◽  
School Activities ◽  
Number Of Factors ◽  
Long Time ◽  
Transport Problems

This paper examines the factors that hinder University accounting students from attending classes on a regular basis. A survey instrument comprising of factors that impede class attendance - adopted from prior studies and modified- was administered to the second, third and the fourth year students doing accounting courses. Descriptive statistics were computed and Independent sample T-tests were performed to measure how statistically significant different the views of students from different years of study were. The results of the study suggest that studying for other tests, uploading of lecture materials to ICT platforms, failure to do the necessary reading in advance of class, working on the project which is due on the same day of a class, lack of proper time management and failure to properly allocate time to school activities are among the ten key factors responsible for class non-attendance. Other hindrances to class attendance include having many lecturers to attend in a day, transport problems to school, lack of personal motivation and a long time lag between classes. In addition, the results reveal that majority of respondents assess their class attendance to be satisfactory; and there is no evidence to indicate that type of course, gender and accommodation status are among the causes of differences in class attendance. Also the results suggest that the higher the levels of study the more the number of factors are considered hindrances to class attendance. These results have implications to students, lecturers, tertiary institutions and sponsors who in one way or the other can devise means to mitigate the problem of class absenteeism.

Education, Training, and Skills Formation

2019 ◽  
pp. 83-105
Author(s):  
Susana Borrás ◽  
Charles Edquist
Keyword(s):  
Literature Review ◽  
Time Lag ◽  
Policy Instruments ◽  
Main Question ◽  
Innovation Activities ◽  
Long Time ◽  
External Sources ◽  
Education Training ◽  
Time Required ◽  
Innovation Policies

The main question that guides this chapter is how governments are focusing (and must focus) on competence-building (education, training, and skills formation) when designing and implementing innovation policies. After a brief literature review, this chapter suggests a typology of internal/external and individual/organizational sources of competences that are related to innovation activities. This serves to examine briefly the most common initiatives that governments are taking in this regard. The chapter identifies three common overall obstacles and barriers in innovation systems in terms of education, training, and skills formation: the insufficient levels of skills and competences in a system, the time lag between firms’ short-term needs for specific competences and the long time required to develop them, and the imbalances between internal and external sources of competences in firms. From these, the chapter elaborates a set of overall criteria for the (re)design and choice of policy instruments that address those obstacles and barriers.

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