To see the other types of publications on this topic, follow the link: Penalty function with memory.
Dissertations / Theses on the topic 'Penalty function with memory'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Penalty function with memory.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Park, Chuljin. "Discrete optimization via simulation with stochastic constraints." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/49088.
Full textAbstract:
In this thesis, we first develop a new method called penalty function with memory (PFM). PFM consists of a penalty parameter and a measure of constraint violation and it converts a discrete optimization via simulation (DOvS) problem with stochastic constraints into a series of DOvS problems without stochastic constraints. PFM determines a penalty of a visited solution based on past results of feasibility checks on the solution. Specifically, assuming a minimization problem, a penalty parameter of PFM, namely the penalty sequence, diverges to infinity for an infeasible solution but converges to zero almost surely for any strictly feasible solution under certain conditions. For a feasible solution located on the boundary of feasible and infeasible regions, the sequence converges to zero either with high probability or almost surely. As a result, a DOvS algorithm combined with PFM performs well even when optimal solutions are tight or nearly tight. Second, we design an optimal water quality monitoring network for river systems. The problem is to find the optimal location of a finite number of monitoring devices, minimizing the expected detection time of a contaminant spill event while guaranteeing good detection reliability. When uncertainties in spill and rain events are considered, both the expected detection time and detection reliability need to be estimated by stochastic simulation. This problem is formulated as a stochastic DOvS problem with the objective of minimizing expected detection time and with a stochastic constraint on the detection reliability; and it is solved by a DOvS algorithm combined with PFM. Finally, we improve PFM by combining it with an approximate budget allocation procedure. We revise an existing optimal budget allocation procedure so that it can handle active constraints and satisfy necessary conditions for the convergence of PFM.
2
Meini, Méndez Iván Fabio. "The penalty: function and requirements." Pontificia Universidad Católica del Perú, 2013. http://repositorio.pucp.edu.pe/index/handle/123456789/116002.
Full textAbstract:
Legitimacy of criminal sanction is originated on its own purposes pursued in a state governed by the Rule of Law. That legitimacy should include the penalty as well as security measures, bearing in mind that both are imposed to someone breaking a rule of conduct, and therefore, someone capable to do it. Reviewing penal capacity or criminal liability concepts is required because if penal capacity means the capacity to understand the reality and adjust the behavior to it, and if every legitimate criminal sanction have to be imposed to someone who have the capacity of break it, then security measures also have to be imposed only to people responsible, capable to understand rules and act in accordance. With regard to people not subject to criminal liability they are standing outside Criminal Law and punish them would be illegitimate. In this line, criminal liability should be seen not only as a crime assumption but also as a basic statement for any dialogue the state shall have with the citizens: at the level of crime itself, proceedings and sentence execution .La legitimación de la sanción penal se deriva de los fines que persigue en un Estado de derecho. Dicha legitimación debe abarcar tanto a la pena como a la medida de seguridad, y tener en cuenta que tanto la pena como la medida de seguridad se imponen a quien infringe una norma de conducta y, por tanto, a quien tiene capacidad para infringirla. Esto presupone revisar el concepto de capacidad penal o imputabilidad,pues si imputabilidad es capacidad para comprender la realidad y adecuar el comportamiento a dicha comprensión, y toda sanción penal legítima ha de imponerse a quien tiene dicha capacidad, también las medidas de seguridad han de ser impuestas solo a imputables. Los verdaderos inimputables son aquellos que están al margen del derecho penal y a quienes resulta ilegítimo imponer alguna sanción. En esta línea, la imputabilidad ha de ser vista no solo como presupuesto del delito, sino como presupuesto de cualquier diálogo que tenga el Estado con el ciudadano con respecto al delito, al proceso y a la ejecución de la pena.
3
Smith, Stephen Bevis. "Exact penalty function algorithms for constrained optimal control problems." Thesis, Imperial College London, 2011. http://hdl.handle.net/10044/1/7996.
Full text
4
Zhao, Xiaobing. "A Penalty Function-Based Dynamic Hybrid Shop Floor Control System." Diss., The University of Arizona, 2006. http://hdl.handle.net/10150/195300.
Full textAbstract:
To cope with dynamics and uncertainties, a novel penalty function-based hybrid, multi-agent shop floor control system is proposed in this dissertation. The key characteristic of the proposed system is the capability of adaptively distributing decision-making power across different levels of control agents in response to different levels of disturbance. The subordinate agent executes tasks based on the schedule from the supervisory level agent in the absence of disturbance. Otherwise, it optimizes the original schedule before execution by revising it with regard to supervisory level performance (via penalty function) and disturbance. Penalty function, mathematical programming formulations, and quantitative metrics are presented to indicate the disturbance levels and levels of autonomy. These formulations are applied to diverse performance measurements such as completion time related metrics, makespan, and number of late jobs. The proposed control system is illustrated, tested with various job shop problems, and benchmarked against other shop floor control systems. In today's manufacturing system, man still plays an important role together with the control system Therefore, better coordination of humans and control systems is an inevitable topic. A novel BDI agent-based software model is proposed in this work to replace the partial decision-making function of a human. This proposed model is capable of 1) generating plans in real-time to adapt the system to a changing environment, 2) supporting not only reactive, but also proactive decision-making, 3) maintaining situational awareness in human language-like logic to facilitate real human decision-making, and 4) changing the commitment strategy adaptive to historical performance. The general purposes human operator model is then customized and integrated with an automated shop floor control system to serve as the error detection and recovery system. This model has been implemented in JACK software; however, JACK does not support real-time generation of a plan. Therefore, the planner sub-module has been developed in Java and then integrated with the JACK. To facilitate integration of an agent, real-human, and the environment, a distributed computing platform based on DOD High Level Architecture has been used. The effectiveness of the proposed model is then tested in several scenarios in a simulated automated manufacturing environment.
5
Dew, M. C. "An exact penalty function algorithm for accurate optimisation of industrial problems." Thesis, University of Hertfordshire, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.353622.
Full text
6
Case, Lori Michelle. "An l??1 penalty function approach to the nonlinear bilevel programming problem." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq21334.pdf.
Full text
7
Chang, Kcomt Romy Alexandra. "Constitutional function assigned to the penalty: Bases for a criminal policy plan." Pontificia Universidad Católica del Perú, 2013. http://repositorio.pucp.edu.pe/index/handle/123456789/116385.
Full textAbstract:
This article intends to analyze treatment and functions assigned to the penalty by our Peruvian Constitution and the way this legal institution is conducted at the prescribed basic penalty level (imposed by the legislator ineach type of criminal offence), the specific penalty level (imposed by the judge according to its individual characteristics in each case) and at the penitentiary enforcement level. Finally recommends some considerations for carrying out a possible legislative reform in accordance with a criminal policy plan within our constitutional framework.El presente trabajo busca efectuar un análisis en torno al tratamiento y las funciones que nuestra Constitución política asigna a la pena, y la manera como dicha institución se desarrolla en nuestro país con respectoa la pena abstracta (la impuesta por el legislador en cada tipo penal), la pena concreta (la impuesta por el juez luego de una individualización en cada casoconcreto), y su ejecución en el ámbito penitenciario. Finaliza proponiendo algunas consideraciones para una eventual reforma legislativa conforme conun plan de política criminal que se encuentre dentro del marco constitucional.
8
Nilsson, Jonna. "Allocentric memory and hippocampal function." Thesis, University of Newcastle Upon Tyne, 2013. http://hdl.handle.net/10443/1864.
Full textAbstract:
Approximately one-third of trauma patients are coagulopathic on arrival to the emergency department. Acute traumatic coagulopathy and systemic inflammatory responses are serious secondary consequences of severe trauma and are linked to increased morbidity and mortality. Early tissue hypoxia is a major component in the aetiology of both complications. New resuscitation strategies are aimed at improving tissue oxygenation in the pre-hospital phase, and may attenuate coagulopathy and inflammatory sequelae. This is of particular importance in military personnel who suffer complex injuries, often from blast exposure, and may have extended evacuation times. This thesis evaluates the effect of a novel hybrid (NH) resuscitation strategy on coagulation and inflammation. Terminally anaesthetised pigs were randomised to one of two injury strands of haemorrhage +/- blast injury; initially resuscitated with 0.9% Saline to a hypotensive systolic blood pressure of 80mmHg for one hour. This was followed by either a return to a normotensive pressure (110mmHg) (NH) or a continuation at the hypotensive level. Over both injury strands NH significantly reduced Prothrombin Time, PT (mean proportion of baseline: 1.40±0.05 vs. 1.80±0.09; p=0.001) and interleukin-6 (IL6) levels (mean 1106±153 vs. 429±79 pg/ml; p=0.001) compared to the hypotensive groups. PT was positively correlated with IL6 (p=0.002) and base deficit (p=0.0004). These findings indicate that improving tissue oxygenation reduces the coagulation derangement and the pro-inflammatory response. No difference in coagulopathy was found between injury strands although blast did cause greater inflammation. Early identification of coagulopathic casualties is essential and a separate feasibility field study was preformed to assess the use of thromboelastometry in a deployed military hospital, evaluating the degree of coagulopathy in battlefield casualties and to monitor the coagulation status during the resuscitation process. In conclusion, NH attenuated the acute traumatic coagulopathy and inflammatory responses and therefore should be considered when an extended casualty evacuation is enforced.
9
Camp, Sophie Jane. "Memory function in multiple sclerosis." Thesis, University College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.327043.
Full text
10
Ozdaryal, Burak. "Exterior Penalty Approaches for Solving Linear Programming Problems." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/33862.
Full textAbstract:
In this research effort, we study three exterior penalty function approaches for solving linear programming problems. These methods are an active set l2 penalty approach (ASL2), an inequality-equality based l2 penalty approach (IEL2), and an augmented Lagrangian approach (ALAG). Particular effective variants are presented for each method, along with comments and experience on alternative algorithmic strategies that were empirically investigated. Our motivation is to examine the relative performance of these different approaches based on the basic l2 penalty function in order to provide insights into the viability of these methods for solving linear programs. To test the performance of these algorithms, a set of randomly generated problems as well as a set of NETLIB test problems from the public domain are used. By way of providing a benchmark for comparisons, we also solve the test problems using CPLEX 6.0, an advanced simplex implementation. While a particular variant (ALAG2) of ALAG performed the best for randomly generated test problems, ASL2 performed the best for the NETLIB test problems. Moreover, for test problems having only equality constraints, IEL2, and ASL2 (which is a finer-tuned version of IEL2 in this case) were comparable and yielded a second-best performance in comparison with ALAG2. Furthermore, a set of problems with relatively higher density parameter values, as well as a set of low-density problems were used to determine the effect of density on the relative performances of these methods. This experiment revealed that for linear programs with a high density parameter, ASL2 is the best alternative among the tested algorithms; whereas, for low-density problems ALAG2 is the fastest method. Moreover, although our implementation was rudimentary in comparison with CPLEX, all of the tested methods attained a final solution faster than CPLEX for the set of large-scale low-density problems, sometimes as fast as requiring only 16-23% of the effort consumed by CPLEX. Average rank tests based on the computational results obtained are performed using two different statistics, that assess the speed of convergence and the quality or accuracy of the solution, in order to determine the relative effectiveness of the algorithms and to validate our conclusions. Overall, the results provide insights into selecting algorithmic strategies based on problem structure and indicate that while this class of methods is viable for computing near optimal solutions, more research is needed to design robust and competitive exterior point methods for solving linear programming problems. However, the use of the proposed variant of the augmented Lagrangian method to solve large-scale low-density linear programs is promising and should be explored more extensively.Master of Science
11
Bose, Gopal Krishna 1955. "Model selection : an optimal approach to constructing a penalty function in small samples." Monash University, Dept. of Econometrics and Business Statistics, 2002. http://arrow.monash.edu.au/hdl/1959.1/8728.
Full text
12
Hill, Vicky. "Memory function in the temporal lobes." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300138.
Full text
13
Al, hashimi Farah. "Sufficient conditions for local exactness of the exact penalty function method in nonsmooth optimization." Miami University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=miami1556652064283587.
Full text
14
Geusa, Federica. "Temperature penalty adimensionale per piccoli e medi campi di sonde geotermiche." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
Find full textAbstract:
Lo scopo di questa Tesi è stato quello di contribuire allo sviluppo dei metodi di dimensionamento e di simulazione dinamica degli scambiatori verticali con il terreno mediante le g-function.
Un primo contributo è stato quello di migliorare le espressioni polinomiali delle g-function determinate da Zanchini e Lazzari (E.Zanchini, S. Lazzari, “Temperature distribution in a field of long Borehole Heat Exchangers (BHEs) subjected to a monthly averaged heat flux”, Energy 59,570-580 (2013)). Sono state perciò ricavate nuove espressioni polinomiali che, a differenza delle precedenti, possono essere sommate fra loro perché valgono a partire dallo stesso istante iniziale. Sono state quindi fornite nuove tabelle di coefficienti.
Sono state poi determinate e utilizzate, mediante combinazioni di g-function, espressioni matematiche adimensionali del temperature penalty per piccoli e medi campi di sonde geotermiche. Questa grandezza viene utilizzata nel metodo di dimensionamento ASHRAE. Bernier, Chahla e Pinel nel loro lavoro “Long-term ground-temperature changes in Geo-Exchange Systems. ASHRAE Transaction, 114(2), 342-50(2008)” hanno fornito tabelle di valori del temperature penalty adimensionale per quattro geometrie di campi sonde. Tali tabelle sono state qui ampliate, calcolando il temperature penalty per campi di sonde a linea singola (1x2, 1x3, 1x4, 1x5, 1x6, 1x7, 1x8), a linea doppia (2x1, 2x2, 2x3, 2x4, 2x5, 2x6, 2x7 e 2x8) e campi quadrati (3x3, 4x4, 5x5).
Infine, utilizzando risultati di calcolo ottenuti utilizzando l’espressione del temperature penalty adimensionale, è stata determinata, per ciascuno dei campi analizzati, una funzione polinomiale approssimata del temperature penalty in funzione del logaritmo del tempo adimensionale. Queste espressioni polinomiali, rese disponibili mediante tabelle dei coefficienti, consentono di ridurre drasticamente i tempi di calcolo nella simulazione dinamica di lungo termine dei campi di sonde considerati.
15
Smith, David S. "The sociosexual function of women's episodic memory." Thesis, University of Aberdeen, 2014. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=210652.
Full textAbstract:
From an adaptive perspective human memory ought to be strategically attuned towards information deemed to be of value according to nature's criterion; i.e. that which promotes individual survival and reproduction. The experiments in this thesis represent an interdisciplinary venture to merge cognitive psychology with social perception research in order to study how sociosexual pressures may have shaped women's episodic memory systems. A vast literature has validated sexual dimorphism as a cue by which women comparatively judge the value of potential mates in terms of their perceived biological and behavioural characteristics (e.g. heightened sexual dimorphism in men correlates with positive biological attributes but also negative behavioural traits). The first 5 experiments extend this work by focusing on the functional contribution women's episodic memory systems may play in constraining generalisations. Experiments 1 and 2 reveal a mnemonic bias in women's memory for contents of encounters with men who have (attractive) masculinised low vs. (less attractive) feminised high pitch. Experiment 3 finds a similar memory benefit for information associated either with masculinised or feminised men's faces, depending on whether women prefer masculinised or feminised characteristics in men. Data from Experiments 6 and 7 reveal further evidence of sociosexual adaptation in women's episodic memory. Memory appears to be biased towards remembering the location of women with feminised (highly attractive) facial features, i.e. high-value competitors for potential mates. While no sociosexual bias was found in women's location memory for attractive male faces, a sociosexual bias was present in women's location memory for men with attractive, low-pitch voices. Considered along with other recent adaptive memory research, the data in this thesis further erode the idea of episodic memory as a general purpose mechanism.
16
Prescott, Carmella Maria. "Self-Reported Memory as a Function of Clinical Versus Everyday Memory Tasks." W&M ScholarWorks, 1990. https://scholarworks.wm.edu/etd/1539625637.
Full text
17
Ouoba, Mahamadi. "Asymptotic expansion of the expected discounted penalty function in a two-scalestochastic volatility risk model." Thesis, Mälardalens högskola, Akademin för utbildning, kultur och kommunikation, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-26100.
Full textAbstract:
In this Master thesis, we use a singular and regular perturbation theory to derive an analytic approximation formula for the expected discounted penalty function. Our model is an extension of Cramer–Lundberg extended classical model because we consider a more general insurance risk model in which the compound Poisson risk process is perturbed by a Brownian motion multiplied by a stochastic volatility driven by two factors- which have mean reversion models. Moreover, unlike the classical model, our model allows a ruin to be caused either by claims or by surplus’ fluctuation. We compute explicitly the first terms of the asymptotic expansion and we show that they satisfy either an integro-differential equation or a Poisson equation. In addition, we derive the existence and uniqueness conditions of the risk model with two stochastic volatilities factors.
18
VanDerwerken, Douglas Nielsen. "Variable Selection and Parameter Estimation Using a Continuous and Differentiable Approximation to the L0 Penalty Function." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2486.
Full textAbstract:
L0 penalized likelihood procedures like Mallows' Cp, AIC, and BIC directly penalize for the number of variables included in a regression model. This is a straightforward approach to the problem of overfitting, and these methods are now part of every statistician's repertoire. However, these procedures have been shown to sometimes result in unstable parameter estimates as a result on the L0 penalty's discontinuity at zero. One proposed alternative, seamless-L0 (SELO), utilizes a continuous penalty function that mimics L0 and allows for stable estimates. Like other similar methods (e.g. LASSO and SCAD), SELO produces sparse solutions because the penalty function is non-differentiable at the origin. Because these penalized likelihoods are singular (non-differentiable) at zero, there is no closed-form solution for the extremum of the objective function. We propose a continuous and everywhere-differentiable penalty function that can have arbitrarily steep slope in a neighborhood near zero, thus mimicking the L0 penalty, but allowing for a nearly closed-form solution for the beta-hat vector. Because our function is not singular at zero, beta-hat will have no zero-valued components, although some will have been shrunk arbitrarily close thereto. We employ a BIC-selected tuning parameter used in the shrinkage step to perform zero-thresholding as well. We call the resulting vector of coefficients the ShrinkSet estimator. It is comparable to SELO in terms of model performance (selecting the truly nonzero coefficients, overall MSE, etc.), but we believe it to be more intuitive and simpler to compute. We provide strong evidence that the estimator enjoys favorable asymptotic properties, including the oracle property.
19
Soeffker, Ninja. "The Use of Probabilistic Risk Functions and Linear Penalty Functions for Hospital Evacuation Planning." Thesis, Virginia Tech, 2014. http://hdl.handle.net/10919/50918.
Full textAbstract:
In Bish et al. (2014), two approaches for the generation of hospital evacuation transportation plans were proposed: the minimization of the overall risk and the minimization of the evacuation duration. The resulting evacuation plans differ in terms of overall risk and duration, but also in the evacuation order of patients with different characteristics, the filling of hospital beds, and the assignments of the patients to the various vehicle types.
Due to the computational effort of the duration minimization, manipulations of the risk functions for the risk minimization approach were searched in this thesis such that the resulting evacuation plans approach the minimal duration without rules for the assignments of patients to vehicle types. It is possible to create risk functions such that the resulting plans have shorter durations than with the basic risk functions, but the overall risk increases and other properties of the plans change.
Furthermore, a new objective function was introduced in this thesis that minimizes an overall penalty function, where penalties are incurred for time intervals in which patients are at the evacuating hospital or being transported. The characteristics of the patients are considered by different weights in the penalty function. For the given problem instance, it is possible to choose penalty factors such that the overall risk is close to the minimal risk or to choose them such that the duration decreases. It is a simple approach with run times that are comparable to the risk minimization approach for the given problem instance.Master of Science
20
Honkala, Keith A. "An analysis of Stokes fluid flow in a converging channel using a penalty function finite element formulation /." Online version of thesis, 1985. http://hdl.handle.net/1850/10283.
Full text
21
Hope, Christopher. "Glucose administration effects on sensorimotor function and declarative memory." Thesis, University of Surrey, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.580354.
Full textAbstract:
This thesis aimed to examine the effects of glucose drink administration on sensorimotor function (studies 1 - 3) and declarative memory (study 4). Glucose had no effect on a modified version of the Hick task in study 1. However in study 2 we observed that glucose slowed reaction times (RTs) during the initial performance of the Eriksen flanker task. One possible reason for this effect is that glucose only slows sensorimotor function when a response is weakly associated with a stimulus, such as at the beginning of task performance. In study 1 stimulus-response (S-R) associations may have been too strong to observe a glucose slowing effect. Here participants performed a greater number of training trials and stimuli were arguably mapped more directly to a response compared to study 2. In study 3 we tested the hypothesis that glucose slows sensorimotor function when S-R associations are weak. Here we used a letter version of the Eriksen flanker task and kept S-R association consistently low by changing the stimulus set to a novel pair of letters every 80 trials. We found that glucose constantly slowed RTs for the duration of this task, a result which is congruent with the hypothesis that glucose slows sensorimotor function when S-R associations are weak. In study 4 we focused on the effects of glucose administration on declarative memory function and sought to determine whether glucose affected the encoding of stimuli in a word recognition task. Here we used ERPs as an online measure of encoding processes. Our findings were that glucose enhanced recognition performance, replicating the well established effect that glucose- facilitates declarative memory. Furthermore, during encoding, glucose affected ERP components associated with early sensory processing, visual word-form generation, lexical/semantic access and long-term memory encoding/consolidation. Furthermore there was a correlation between recognition performance and the degree to which glucose amplified the N400 component, an ERP potential associated with lexical/semantic access. The results of this study therefore indicate that glucose modulates encoding processes and that these effects may, at least partially, underlie the glucose facilitation of declarative memory.
22
Lee, Jong Min. "A Study on Architecture, Algorithms, and Applications of Approximate Dynamic Programming Based Approach to Optimal Control." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/5048.
Full textAbstract:
This thesis develops approximate dynamic programming (ADP) strategies suitable for process control problems aimed at overcoming the limitations of MPC, which are the potentially exorbitant on-line computational requirement and the inability to consider the future interplay between uncertainty and estimation in the optimal control calculation. The suggested approach solves the DP only for the state points visited by closed-loop simulations with judiciously chosen control policies. The approach helps us combat a well-known problem of the traditional DP called 'curse-of-dimensionality,' while it allows the user to derive an improved control policy from the initial ones. The critical issue of the suggested method is a proper choice and design of function approximator. A local averager with a penalty term is proposed to guarantee a stably learned control policy as well as acceptable on-line performance. The thesis also demonstrates versatility of the proposed ADP strategy with difficult process control problems. First, a stochastic adaptive control problem is presented. In this application an ADP-based control policy shows an "active" probing property to reduce uncertainties, leading to a better control performance. The second example is a dual-mode controller, which is a supervisory scheme that actively prevents the progression of abnormal situations under a local controller at their onset. Finally, two ADP strategies for controlling nonlinear processes based on input-output data are suggested. They are model-based and model-free approaches, and have the advantage of conveniently incorporating the knowledge of identification data distribution into the control calculation with performance improvement.
23
Ghosh, Jayanto K. "Finite element simulation of non-Newtonian flow in the converging section of an extrusion die using a penalty function technique." Ohio : Ohio University, 1989. http://www.ohiolink.edu/etd/view.cgi?ohiou1172094913.
Full text
24
Wyatt, James Kelley. "Psychophysiological analysis of memory function during the sleep onset transition." Diss., The University of Arizona, 1995. http://hdl.handle.net/10150/187137.
Full textAbstract:
This dissertation presents an examination of explicit and implicit memory for auditory stimuli presented immediately prior to sleep onset. The paper begins with a review and critical analysis of the research findings published in the areas of sleep and memory, event-related potentials and sleep, and event-related potentials and memory. In the present study, thirty undergraduate subjects (17 female and 13 male) were presented with auditory stimuli in an oddball paradigm (single-syllable concrete nouns and 50-msec 1000-Hz beeps in a 1:4 ratio) until sleep onset. They were allowed to accumulate either 30 seconds or 10 minutes of sleep, awakened, and tested for free recall and recognition memory for the meaningful stimuli. Results from event-related potentials recorded during the stimulus presentation phase supported the conclusion that subjects continued to process the meaningful stimuli until sleep onset. After 10 minutes of sleep, but not after 30 seconds of sleep, subjects had profound amnesia on free recall for stimuli presented in the four minute window prior to sleep onset. Increased beta EEG power during the sleep period correlated positively with recall of stimuli in the four minute window. In the 30 second condition (versus the 10 minute condition), subjects responded significantly faster in the recognition task to words correctly recognized. It is concluded that when allowed to sleep for 10 minutes, subjects evidenced a mixed anterograde and retrograde amnesia for auditory stimuli presented in the four minute window prior to sleep onset. The results are discussed in terms of stimulus encoding, memory consolidation, and information retrieval. It is hypothesized that during the sleep onset transition, explicit memory systems switch from processing new information, to becoming a dedicated system for reprocessing information presented during the presleep period. Suggestions are given for further research, including studies of various sleep-disordered populations and the use of modified protocols.
25
Blaskovits, Farriss. "Endocannabinoid Function in Hippocampal Synaptic Plasticity and Spatial Working Memory." Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/26106.
Full textAbstract:
Cannabis has been used medicinally for millennia, but the cannabinoid (CB) field exploded with the identification of its endogenous receptors and endocannabinoids (eCBs). In vitro experimentation established that eCBs alter synaptic plasticity at presynaptic nerve terminals; however, the characterization of the eCB system (ECS) in vivo remains incomplete. This study aimed to determine the mechanism of in vivo eCB-mediated hippocampal synaptic plasticity and
to analyze the effects this plasticity had on spatial working memory (SWM). With in vivo
recordings of field excitatory postsynaptic potentials (fEPSPs) in anesthetized mice and rats as well as pharmacological manipulation of the ECS and glutamate receptor antagonism, it was found that eCBs, both anandamide (AEA) and 2-arachnidonyl glycerol (2-AG), caused LTD at hippocampal CA3-CA1 synapses. Induction of eCB-LTD occurs via a sequential activation of
cannabinoid type-1 receptor (CB1R) and NR2B-containing NMDA receptor (NR2BR) and is
expressed through the endocytosis of AMPA receptors (AMPARs). Increased eCB tone also
caused an impairment of SWM for over 24 hours in the Delayed Non-Match-To-Sample (DNMTS) T-maze. This study provides the first evidence that an acute administration of eCB degradative enzyme inhibitors not only produces an in vivo LTD at hippocampal CA3-CA1
synapses that requires CB1R, NR2BR, and AMPAR, but also impairs SWM, a phenomenon also
caused by an acute injection of exogenous CBs.
26
Riches, I. "Aspects of medial temporal lobe function in relation to memory." Thesis, University of Bristol, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379529.
Full text
27
Shaikh, Sajid S. "COMPUTATION IN SOCIAL NETWORKS." Kent State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=kent1185560088.
Full text
28
Madabushi, Ananth R. "Lagrangian Relaxation / Dual Approaches For Solving Large-Scale Linear Programming Problems." Thesis, Virginia Tech, 1997. http://hdl.handle.net/10919/36833.
Full textAbstract:
This research effort focuses on large-scale linear programming problems that arise in the context of solving various problems such as discrete linear or polynomial, and continuous nonlinear, nonconvex programming problems, using linearization and branch-and-cut algorithms for the discrete case, and using polyhedral outer-approximation methods for the continuous case. These problems arise in various applications in production planning, location-allocation, game theory, economics, and many engineering and systems design problems. During the solution process of discrete or continuous nonconvex problems using polyhedral approaches, one has to contend with repeatedly solving large-scale linear programming(LP) relaxations. Thus, it becomes imperative to employ an efficient method in solving these problems. It has been amply demonstrated that solving LP relaxations using a simplex-based algorithm, or even an interior-point type of procedure, can be inadequately slow ( especially in the presence of complicating constraints, dense coefficient matrices, and ill-conditioning ) in comparison with a Lagrangian Relaxation approach. With this motivation, we present a practical primal-dual subgradient algorithm that incorporates a dual ascent, a primal recovery, and a penalty function approach to recover a near optimal and feasible pair of primal and dual solutions.
The proposed primal-dual approach is comprised of three stages. Stage I deals with solving the Lagrangian dual problem by using various subgradient deflection strategies such as the Modified Gradient Technique (MGT), the Average Direction Strategy (ADS), and a new direction strategy called the Modified Average Direction Strategy (M-ADS). In the latter, the deflection parameter is determined based on the process of projecting the unknown optimal direction onto the space spanned by the current subgradient direction and the previous direction. This projected direction approximates the desired optimal direction as closely as possible using the conjugate subgradient concept. The step-length rules implemented in this regard are the Quadratic Fit Line Search Method and a new line search method called the Directional Derivative Line Search Method in which we start with a prescribed step-length and then ascertain whether to increase or decrease the step-length value based on the right-hand and left-hand derivative information available at each iteration. In the second stage of the algorithm (Stage II), a sequence of updated primal solutions is generated using some convex combinations of the Lagrangian subproblem solutions. Alternatively, a starting primal optimal solution can be obtained using the complementary slackness conditions. Depending on the extent of feasibility and optimality attained, Stage III applies a penalty function method to improve the obtained primal solution toward a near feasible and optimal solution.
We present computational experience using a set of randomly generated, structured, linear programming problems of the type that might typically arise in the context of discrete optimization.Master of Science
29
Neukamm, Ashley Marie. "Material Imperfection: Mapping Form Through Memory." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1397662164.
Full text
30
Schwarb, Hillary. "Optimized cognitive training: investigating the limits of brain training on generalized cognitive function." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/47599.
Full textAbstract:
Since antiquity, philosophers, theologians, and scientists have been interested in human memory; however, researchers today are still working to understand the capabilities, boundaries, and architecture. While the storage capabilities of long-term memory are seemingly unlimited (Bahrick, 1984), working memory, or the ability to maintain and manipulate information held in memory, seems to have stringent capacity limits (e.g., Cowan, 2001). Individual differences, however, do exist and these differences can often predict performance on a wide variety of tasks (cf. Engle, 2001). Recently, researchers have promoted the enticing possibility that simple behavioral training can expand the limits of working memory which indeed may also lead to improvements on other cognitive processes as well (cf. Morrison&Chein, 2011). The current study investigated this possibility. Recommendations from the skill training literature (cf. Schneider, 1985) were incorporated to create optimized verbal and spatial working memory training tasks. Significant performance improvements were evident across eight days of cognitive training using verbal and spatial adaptive n-back procedures. Training-related improvements were also evident for some untrained measures of visual short-term memory, attentional control, and working memory. These training effects, however, were not universal. Other measures of visual short-term memory and attentional control, as well as measures of fluid intelligence were unaffected by training.
31
Olesen, Pernille J. "Brain function and behaviour related to development and training of working memory /." Stockholm, 2005. http://diss.kib.ki.se/2005/91-7140-506-2/.
Full text
32
Christian, Leonie Marie. "The effect of glucose on memory and aspects of cognitive function." Thesis, University of Bristol, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.541645.
Full text
33
Bilić, Katja. "Relationship between memory performance, visuospatial function and functional lateralization in adults." Thesis, Umeå universitet, Institutionen för psykologi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-105777.
Full textAbstract:
Age-related decline in memory and other cognitive functions, such as visuospatial functions is widely studied and well documented. In recent years, some studies have also found relationships between memory performance and functional body lateralization, with individuals who are inconsistently lateralized (e.g. have inconsistent handedness) scoring higher on episodic memory tests. The objectives of this study were to investigate relationships and possible differences between episodic and semantic memory performance, and visuospatial functions as a function of functional lateralization consistency in a large population-based study. In total, 1283 adult men and women participants, with age ranging from 25 to 100 years, were tested within the Betula prospective cohort study (Nilsson et al., 1997) where they were included in the fifth wave (T5) of data collection. Participants were divided into groups of consistent or inconsistent functional lateralization regarding respective hand-, foot-, and eyedness. Results revealed weak to moderate relationship between variables of functional laterality and its consistency. While age was significant predictor of memory performance and visuospatial functions, sex and functional laterality consistency variables were insignificant. Results are discussed in relation to previous studies and to hemispheric interaction theory.Betula prospective cohort study (Nilsson et al., 1997, 2004)
34
Elam, Kit. "MEMORY AND DEFAULT NETWORK ACTIVATION AS A FUNCTION OF APOE GENOTYPE." OpenSIUC, 2010. https://opensiuc.lib.siu.edu/dissertations/204.
Full textAbstract:
The main purpose of this dissertation project was to assess the behavioral and neural correlates of Episodic Memory as a function of the APOE genotype in a healthy young adult sample. To accomplish this, 98 subjects completed behavioral tasks assessing visual memory, working memory, episodic memory, and attention. Subjects also completed questionnaires evaluating IQ, years of education, drug use, personality, and emotional traits. These subjects were also genotyped for the APOE gene, resulting in 29 APOE-ε4 carriers (subjects who had at least one ε4 allele) and 69 Non APOE-ε4 carriers (having no ε4 alleles). No differences were found between genotypic groups on any demographic characteristics, behavioral measures, or personality traits. From this larger pool of 98 subjects, a subset of 22 subjects (10 APOE-ε4, 12 Non APOE-ε4) completed additional behavioral tasks while undergoing functional magnetic resonance imaging. While being scanned, subjects were asked to learn word pairs during an encoding phase, make metamemory evaluations on their ability to later remember each word pair during a judgment of learning (JOL) task, and try to discriminate between original and recombined word pairs during a final recognition phase. Interspersed between these tasks was a rest task meant to elicit activity within the Default Network. No differences in memory or metamemory performance were found on the behavioral tasks administered during imaging based on genotype. In contrast, marked differences in brain activation were found between APOE-ε4 carriers and Non APOE-ε4 carriers across the various imaging tasks. During encoding, APOE-ε4 carriers were found to have greater activation than Non APOE-ε4 carriers in the dorsal anterior portion of the left superior temporal gyrus, cingulate gyrus, and anterior middle frontal gyrus. This same pattern - greater APOE-ε4 carrier activation as compared to Non APOE-ε4 carriers - was present in the parahippocampal gyrus and posterior middle temporal gyrus during the judgment of learning metamemory task. During the recognition task, greater activation was found for Non APOE-ε4 carriers versus APOE-ε4 carriers in the left parahippocampal gyrus, SPL, and right anterior superior frontal gyrus. During the rest task, greater activation was seen in APOE-ε4 carriers versus Non APOE-ε4 carriers in the left inferior frontal gyrus, whereas the converse comparison resulted in medial anterior cingulate activation. The lack of behavioral differences suggests that in a healthy young adult sample, as was used in the present study, there are not yet detectable behavioral differences as a function of APOE genotype. The greater neural activity seen in APOE-ε4 carriers during the encoding and judgment of learning tasks is likely to reflect neural compensation: young adult APOE-ε4 carriers compensate for declines in cognitive efficiency with greater neural activity such that this greater neural activity improves behavioral performance, particularly in memory domains (Buckner, Andrews-Hanna, & Schacter, 2008; Han & Bondi, 2008; Levy et al., 2004; Trivedi et al., 2008). The relatively lower levels of activation in APOE-ε4 carriers during the recognition task may reflect stronger memory traces for studied items as a result of greater frontal and medial temporal lobe activity during the encoding and judgment of learning tasks in the APOE-ε4 carriers (Kirwan, Wixted, & Squire, 2008; Mondadoori et al., 2007; Squire, Wixted, & Clark, 2007). In the present sample, a lack of behavioral differences accompanied by neural disparity may signal the precursors of Alzheimer's disease, highlighting the progressive deteriorating influence of the APOE-ε4 allele. The aberrant pattern of default network activity seen in APOE-ε4 carriers underlies this influence as this genotype is proposed to preferentially contribute to the causes of Alzheimer's disease in areas common to the Default Network and Episodic Memory (Buckner et al., 2008). The present results strengthen previous findings illustrating a connection between the brain activity underlying memory processes, the default network, and the APOE genotype.
35
Pereira, Ana Rita Salgueiro. "HPA axis function and episodic memory loss in early Alzheimer disease." Master's thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/12509.
Full textAbstract:
Mestrado em Bioquímica - Bioquímica ClínicaAlzheimer’s disease (AD) is a brain neurodegenerative disease leading to progressive loss of memory and intellectual abilities. It is characterized by the appearance of amyloid-β oligomers (Aβ), which then aggregate into plaques, progressive appearance of neurofibrillary tangles composed of hyperphosphorylated tau, synaptic impairment and neuronal death. The hippocampus, a key structure responsible for memory encoding, is the first brain region affected in AD leading to early episodic memory loss. Aβ accumulation seems to have an important role in triggering chronic stress in AD, compromising the hypothalamic-pituitary-adrenal (HPA) axis function and the structures involved in its regulation, notably the hippocampus. The purpose of the present study was to evaluate the HPA axis function and episodic-like memory in a model of AD, the Tg2576 mice, in the early phase of the pathology, which was defined in these mice at about 4 months of age. To study the HPA axis function, corticosterone, the main stress hormone, was quantified by ELISA at the onset of light phase, at the onset of dark phase and after inducing the negative feedback with a dexamethasone supression test. Hippocampal glucorticoid receptors (GRs) were also quantified by Western blot. Tg2576 mice showed impairment in HPA axis, characterized by an increase in corticosterone at the onset of active phase and an absence in the negative feedback response induced by dexamethasone. Also, hippocampal GRs are increased and seems to fail in the downregulation of the stress response mediated by the HPA axis. To evaluate episodic-like memory, an object recognition task was conducted, which combines the ability to remember the ‘what, when and where’ components of an event. A deficit in the ‘where’ component of this type of memory was observed in Tg2576 mice. An in vivo treatment with the GR antagonist RU486 was then applied to evaluate if blocking GR function could reverse this deficit. Our first results suggest that blocking GR function can prevent this memory deficit in Tg2576 mice. These data demonstrate that corticostesterone levels, and thus stress signaling, are increased in the early phase of AD in these mice, due to dysfunction of the HPA axis. Furthermore, this altered signaling, via GRs, probably contributes to the early episodic memory deficits observed in these mice. These data strongly support our hypothesis that elevated stress is an environmental factor contributing to the onset of AD neuropathology.
A Doença de Alzheimer (DA) é uma doença neurodegenerativa do tecido cerebral que leva à perda da memória e das propriedades intelectuais. É caracterizada pelo aparecimento de oligómeros de amilóide-β (Aβ) que depois se agregam em placas, aparecimento progressivo de agregados neurofibrilares constituídos por proteína tau hiperfosforilada, alterações sinápticas e morte neuronal. O hipocampo, uma estrutura chave responsável pela codificação da memória, é a primeira região cerebral afectada na DA levando numa fase precoce, à perda da memória episódica. A acumulação de Aβ parece ter uma função importante no desencadeamento de stress crónico na DA levando ao comprometimento da função do eixo HPA e das várias estruturas envolvidas na sua regulação, nomeadamente o hipocampo. Neste estudo pretendeu-se estudar a função do eixo HPA e avaliar a memória episódica usando um modelo transgénico da DA, o ratinho Tg2576, numa fase precoce da doença de Alzheimer, definida neste modelo por volta dos 4 meses. Os estudos relativos à função do eixo HPA foram feitos através da quantificação de corticosterona, a hormona principal no stress, por teste ELISA na fase de repouso, na fase activa e após teste de supressão pela dexametasona. Quantificaram-se ainda os receptores aos glucocorticoides (RGs) no hipocampo por western blot. Os ratinhos Tg2576 mostraram um comprometimento do eixo HPA, caracterizada pelo aumento de corticosterona no ínicio da fase activa e ausência de regulação negativa induzida pela dexametasona. Ainda, os RGs estão aumentados e mostram comprometimento na regulação negativa induzida no eixo HPA. Para avaliar a memória episódica foi efectuado um teste de reconhecimento de objectos que combina a capacidade de recordar o ‘quê, quando e onde’ de um evento. Os ratinhos Tg2576 apresentaram um deficit na componente ‘onde’ deste tipo de memória. Foi em seguida aplicado um tratamento in vivo com um antagonista dos RGs (RU486) para avaliar se bloqueando a função dos RGs se poderia reverter o deficit observado. Os nossos primeiros resultados revelam que o bloqueia dos RGs pode prevenir o deficit na memória episódica. Assim este trabalho mostrou que os ratinhos Tg2576 apresentam uma perturbação ao nível do eixo HPA e da sua regulação pelos RG do hipocampo, traduzidos por um nível de stress aumentado, e perturbação ao nível da memória episódica. Este trabalho mostra que o nível de stress está aumentado numa fase muito precoce da DA neste ratinho devido à disfunção do eixo HPA. Para além disso, a alteração nesta sinalização mediada pelos RGs, contribui provavelmente para os deficits precoces na memória episódica observados neste ratinho. Estes resultados suportam a nossa hipótese de que o stress é um factor de risco muito importante no desenvolvimento precoce da neuropatologia na doença de Alzheimer.
36
Martin, Matthew David. "Time-dependent alterations in memory CD8 T cell function after infection." Diss., University of Iowa, 2016. https://ir.uiowa.edu/etd/3138.
Full textAbstract:
CD8 T cells play a critical role in the clearance of pathogenic bacteria, viruses, and protozoan parasites. Upon encountering their cognate antigen through either infection or vaccination, naïve CD8 T cells undergo robust proliferative expansion, which is followed by contraction and the formation of a memory population. Memory CD8 T cells are long-lived, and because they persist in increased numbers and possess enhanced functional abilities compared to naïve CD8 T cells, they are able to provide the host with increased protection following re-infection. Because of these properties, vaccines designed to elicit memory CD8 T cells have the potential to reduce health care burdens related to infection with pathogens including human immuno deficiency virus (HIV), malaria, influenza, and hepatitis virus. However, stimulating protective CD8 T cell responses against these pathogens through vaccination has proven challenging. Therefore, a better understanding of the properties of memory CD8 T cells generated following vaccination, and the characteristics of memory CD8 T cells best suited for providing protection against diverse pathogens is needed.
While memory CD8 T cells can be maintained for as long as the life of the host, evidence suggests that their properties change with time after infection. Because CD8 T cell-mediated protection is based upon both the numbers and quality or functional abilities of memory cells present at the time of re-infection, changes in memory CD8 T cell function over time could impact their ability to provide protection upon re-infection. Therefore, a better understanding of how memory CD8 T cells change with time after infection is needed. As part of the studies presented in this thesis, I found that the phenotype and function of memory CD8 T cells including localization, interleukin (IL)-2 cytokine production, responsiveness to homeostatic cytokines, metabolic capabilities, and proliferation and secondary memory generation potential change with time after infection. Interestingly functional changes could not be completely explained by changes in subset composition that occur with time, as changes over time were also seen in defined CD62Lhi subsets. Importantly, functional changes of memory CD8 T cells that occurred with time led to an increased ability to provide protection against a chronic viral infection. These data improve our knowledge of the capabilities of memory CD8 T cells generated following infection, and suggests that the outcome of vaccination strategies designed to elicit protective memory CD8 T cells using single or prime-boost immunizations will depend upon the timing between antigen encounters.
Following re-infection, memory CD8 T cells become activated and produce effector cytokines and cytolytic molecules that aid the host in clearing invading microbes. Activation can be triggered not only through cognate antigen recognition, but also by antigen-independent cytokine driven signals. However, our knowledge of how antigen-dependent and –independent signals contribute to CD8 T cell activation and protection following infection is incomplete. In the second part of my thesis, I show that the ability of memory CD8 T cells to become activated in response to inflammation decreases with time after infection, that antigen and inflammation act synergistically to induce activation of memory CD8 T cells, that the presence of cognate antigen enhances activation of memory CD8 T cells that contribute to clearance of infection, and that bystander memory CD8 T cell responses following unrelated bacterial infection do not provide the host with a protective benefit.
Together, the data in this thesis further our understanding of memory CD8 T cells generated following infection and/or vaccination, and the properties of memory CD8 T cells important for providing protection upon re-infection with invading pathogens.
37
Cendón, Carla. "Function and compartmentalization of circulating versus tissue resident memory T cells." Doctoral thesis, Humboldt-Universität zu Berlin, 2019. http://dx.doi.org/10.18452/19794.
Full textAbstract:
Verstärkte Anstrengungen zur Förderung der T-Zell-basierten Immunität haben eine zwingende Notwendigkeit für unser Verständnis der menschlichen T-Zell-Funktion und –Erhaltung geschaffen. Das Paradigma, dass Gedächtnis-T-Lymphozyten kontinuierlich durch den Körper zirkulieren wurde vor kurzem durch die Entdeckung der Gedächtnis-T-Zellen, die in einer Vielzahl von Geweben, einschließlich des Knochenmarks angesiedelt sind, herausgefordert. Allerdings bleibt der Unterschied zwischen Funktionsweise von zirkulierenden und gewebeansässigen Gedächtnis-T-Zellen nur unzulänglich verstanden.
Die Knochenmark ist die Heimat für eine große Anzahl Gedächtnis-T-Zellen. CD4+ Gedächtnis-T-Zellen aus dem Knochenmark beinhalten ein breites Spektrum an Antigenspezifitäten. Interessanterweise wurden CD4+ Gedächtnis-T-Zellen spezifisch für systemische Kindheitsantigene im Knochenmark von älteren Menschen gefunden, auch wenn sie nicht mehr in der Blutzirkulation nachgewiesen werden konnten. Gedächtnis-T-Zellen aus dem Knochenmark sind sesshaft und ruhend und Langzeitgedächtnis gegen systemische Antigene erhalten. Sowohl der Überlebensmechanismus von Gedächtnis-T-Zellen, als auch die Kapazität von gewebsansässigen Gedächtnis-T-Zellen nach einer systemischen Herausforderung mobilisiert zu werden, sind bisher nur unzureichend geklärt.
Ich habe gezeigt, dass Gedächtnis-T-Zellen aus dem peripheren Blut und Knochenmark unterschiedliche Überlebensfähigkeiten haben. Weiterhin habe ich die Rolle von Überleben Faktoren in ihrer Erhaltung identifiziert. Zudem habe ich bestimmt, dass Gedächtnis-T-Zellen aus dem Blut und Knochenmark unterschiedliche Zellpopulationen sind, mit unterschiedliche TCRβ Repertoires. Schließlich konnte ich zeigen, dass sesshafte Gedächtnis-T-Zellen, die spezifisch für systemische Antigene sind, schnell in die Blutzirkulation mobilisiert werden. Zusammenfassend bieten diese Studien ein umfassenderes Verständnis der Funktion und des Erhalts des immunologischen Gedächtnisses.Intensified efforts to promote protective T cell-based immunity in vaccines and immunotherapies have created a compelling need to expand our understanding of human T cell function and maintenance. The paradigm that memory T lymphocytes are continuously circulating through the body in search of their cognate antigen has been recently challenged by the discovery of memory T cells residing in a variety of tissues, including the bone marrow (BM). However, the division of labor and lifestyle of circulating versus tissue resident memory T cells remains poorly understood. The human BM is home to a great number of memory T cells. BM memory CD4+ T cells contain a wide array of antigen specificities. Interestingly, memory CD4+ T cells specific for systemic childhood antigens have been found in the BM of elderly humans, even when they were no longer detectable in peripheral blood (PB) circulation. BM memory T cells are resident, resting and maintain long-term memory to systemic antigens. The survival mechanisms of circulating and BM resident memory T cells; as well as the capacities of tissue resident memory T cells to be mobilized into blood circulation after systemic antigen re-challenge to confer us with immune protection remains to be elucidated. I have shown that PB and BM memory T cells have different survival capacities, as well as identified the role of survival factors in their maintenance. Moreover, using sequencing analysis of the TCRβ repertoire, I have determined that PB and BM memory T cells are separated cell populations. Finally, by tracking the dynamics of antigen-specific memory CD4+ T cells after systemic MMR re-vaccination I could show that TRM CD4+ T cells specific for systemic antigens can be rapidly mobilized into blood circulation and contribute to the immune response. These studies provide a more comprehensive understanding of the function and maintenance of immunological memory in humans.
38
Carpenter, Stephen M. "Memory CD8+ T Cell Function during Mycobacterium Tuberculosis Infection: A Dissertation." eScholarship@UMMS, 2016. http://escholarship.umassmed.edu/gsbs_diss/860.
Full textAbstract:
T cell vaccines against Mycobacterium tuberculosis (Mtb) and other pathogens are based on the principle that memory T cells rapidly generate effector responses upon challenge, leading to pathogen clearance. Despite eliciting a robust memory CD8+ T cell response to the immunodominant Mtb antigen TB10.4 (EsxH), we find the increased frequency of TB10.4-specific CD8+ T cells conferred by vaccination to be short-lived after Mtb challenge. To compare memory and naïve CD8+ T cell function during their response to Mtb, we track their expansions using TB10.4-specific retrogenic CD8+ T cells. We find that the primary (naïve) response outnumbers the secondary (memory) response during Mtb challenge, an effect moderated by increased TCR affinity. To determine whether the expansion of polyclonal memory T cells is restrained following Mtb challenge, we used TCRb deep sequencing to track TB10.4-specific CD8+ T cells after vaccination and subsequent challenge in intact mice. Successful memory T cells, defined by their clonal expansion after Mtb challenge, express similar CDR3b sequences suggesting TCR selection by antigen. Thus, both TCR-dependent and independent factors affect the fitness of memory CD8+ responses. The impaired expansion of the majority of memory T cell clonotypes may explain why some TB vaccines have not provided better protection.
39
Allen, Rebecca J. "Selection of memory book content: Agreement in content as a function of informant relationship to memory book recipient." Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/6795.
Full textAbstract:
This study was designed to determine to what extent provision of personally relevant information and sensory cues would agree between Recipient and Informant for selection of memory book content. Six dyads married to each other an average of 29.17 years (SD = 10.03), between the ages of 43 and 70 years (Mean = 57; SD = 8.39), and cognitively competent (i.e., no diagnosis of cognitive impairment) participated. Participants completed questionnaires independently and provided personally relevant information/memories, aversions towards select memories/topics, and sensory cues on behalf of themselves (as “Recipient) and their spouse (as “Informant”). For provision of personally relevant information/memories, Informant and Recipient was 44.58% in agreement (SD = 14.99). For provision of aversions towards select memories/topics, Informant and Recipient was 24.86% in agreement (SD = 30.81). For provision of sensory cues, Informant and Recipient was 19.6% in agreement (SD = 30.81). Findings suggest that memory books made by others may not include the most important memories of the Recipient, thereby limiting the effectiveness of the memory book. Therefore, efforts should be made to encourage individuals to create a memory book while cognitively competent or share their most meaningful memories with the person who is most likely to make them a memory book if they should need one in the future.
40
Janušauskas, Arūnas. "Gerber-Shiu baudos funkcijos skaičiavimas Pareto žaloms." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2010~D_20110709_152450-24338.
Full textAbstract:
Savo darbe mes nagrinėjame Gerber-Shiu baudos funkciją klasikiniame rizikos modelyje atveju, kai žalų dydžiai pasiskirstę pagal Pareto dėsnį. Pagrindinis uždavinys yra susikonstruoti algoritmą funkcijos reikšmių gavimui. Tiriamas Gerber-Shiu diskontuotos baudos funkcijos atvejis, kada vidinė baudos funkcija w tapačiai lygi vienetui. Dėl sudėtingos transformuoto Pareto skirstinio formos analitiškai paskaičiuoti sąsūkų nepavyko. Tam tikslui naudojamas interpoliavimas kubiniu splainu. N kartų kartodami sukonstruotą algoritmą gauname pirmąsias n sąsūkas laisvai pasirinktiems pradiniams parametrams: Pareto skirstinio laipsnio rodikliui α, pradiniam kapitalui u, santykinei draudimo priemokai θ, diskontavimo parametrui (palūkanų normai) δ ir Puasono proceso parametrui λ. Lentelių pagalba parodome funkcijos priklausomybę nuo skirtingų modeliuojančių parametrų reikšmių. Išvadose teigiame jog pasiūlytas metodas skaičiuoti Gerber-Shiu diskontuotos baudos funkciją nors ir išpildomas tačiau yra neefektyvus. Kai kuriais pradinių parametrų pasirinkimo atvejais susiduriama su tikslumo problema. Norint tiksliai paskaičiuoti funkcijos reikšmes reikia didesnių eilių transformuoto Pareto skirstinio sąsūkų, o tam reikalingi dideli resursai. Kita vertus, pradinio kapitalo u reikšmėms didėjant tikslumas didėja ženkliai.In this paper we consider Gerber-Shiu discounted penalty function in the classical risk model for Pareto claims. Our main goal is to construct an algorithm for obtaining values of the discounted penalty function (considering penalty function w=1). Due to the complicated form of the transformed Pareto distribution function we cannot obtain its convolutions analiticaly. We use numerical methods provided by Maple (cube spline) to find interpolating functions instead. Continuously applying recursive formulas we obtain first 5 interpolated convolutions. Then we calculate values of Gerber-Shiu discounted penalty function for certain arbitrary parameters: α – degree of Pareto distribution function, initial surplus u, security loading θ, discounting parameter δ and Poison process parameter λ. We present data tables and graphs of the discounted penalty function for some variations of parameters in later sections. Finally we state that the method that we use is quite complicated. For better accuracy of the discounted penalty function values one may require to get many convolutions of the transformed Pareto distribution function and that may require too great of the resources. However the quantity of the convolutions needed rapidly decreases for large values of the initial surplus u.
41
Raj, Vinaya. "Episodic Memory Development in Childhood: Contributions from Brain Electrical Activity and Executive Functions." Diss., Virginia Tech, 2012. http://hdl.handle.net/10919/37641.
Full textAbstract:
Episodic memory is a critical component of human cognition. Episodic memory involves recollection of the contextual details surrounding an event, the capacity for mental time travel of past and future events, and is characterized by the subjective awareness that an event has been personally experienced. It is fundamental to our understanding of this complex memory system to examine how episodic memory emerges during the course of development. The present investigation explored the developmental improvement in episodic memory processing assessing recollection of factual information and the source of this information (i.e., source memory) between early to middle childhood. The electrophysiological (EEG) correlates of fact and source memory processing and measures of executive function were also examined as potential sources of variation in episodic memory. The focus of Study 1 was to examine source memory development in early childhood in a sample of 4- and 6-year-olds. Results revealed that older children were better able to recall both fact and source information. Source memory measures were correlated to early executive ability, namely measures of working memory, inhibitory control and set-shifting. Frontal EEG accounted for unique variation in fact recall but not source recall, whereas temporal EEG did not predict fact or source recall performance. The focus of Study 2 was to examine source memory development in middle childhood in a sample of 6- and 8-year-olds. Older children were better on fact recall, but both ages were comparable on source recall. Frontal EEG uniquely predicted fact recall performance beyond the contribution of age and language. Both frontal and parietal EEG and executive function predicted variation in source recall performance. In contrast, temporal EEG did not uniquely predict fact or source recall performance. Lastly, Study 3 was a longitudinal investigation of source memory between early and middle childhood. Although age-related increases in performance were evident, Time 1 and Time 2 source memory measures were not correlated. This investigation contributes to our understanding of the developmental changes in source memory processing between early and middle childhood, and identifies that patterns of frontal and parietal brain activity and executive function skills contribute to early episodic memory formation.Ph. D.
42
Longden, Kit. "Constraining the function of CA1 in associative memory models of the hippocampus." Thesis, University of Edinburgh, 2005. http://hdl.handle.net/1842/770.
Full textAbstract:
CA1 is the main source of afferents from the hippocampus, but the function of CA1 and its perforant path (PP) input remains unclear. In this thesis, Marr’s model of the hippocampus is used to investigate previously hypothesized functions, and also to investigate some of Marr’s unexplored theoretical ideas. The last part of the thesis explains the excitatory responses to PP activity in vivo, despite inhibitory responses in vitro. Quantitative support for the idea of CA1 as a relay of information from CA3 to the neocortex and subiculum is provided by constraining Marr’s model to experimental data. Using the same approach, the much smaller capacity of the PP input by comparison implies it is not a one-shot learning network. In turn, it is argued that the entorhinal-CA1 connections cannot operate as a short-term memory network through reverberating activity. The PP input to CA1 has been hypothesized to control the activity of CA1 pyramidal cells. Marr suggested an algorithm for self-organising the output activity during pattern storage. Analytic calculations show a greater capacity for self-organised patterns than random patterns for low connectivities and high loads, confirmed in simulations over a broader parameter range. This superior performance is maintained in the absence of complex thresholding mechanisms, normally required to maintain performance levels in the sparsely connected networks. These results provide computational motivation for CA3 to establish patterns of CA1 activity without involvement from the PP input. The recent report of CA1 place cell activity with CA3 lesioned (Brun et al., 2002. Science, 296(5576):2243-6) is investigated using an integrate-and-fire neuron model of the entorhinal-CA1 network. CA1 place field activity is learnt, despite a completely inhibitory response to the stimulation of entorhinal afferents. In the model, this is achieved using N-methyl-D-asparate receptors to mediate a significant proportion of the excitatory response. Place field learning occurs over a broad parameter space. It is proposed that differences between similar contexts are slowly learnt in the PP and as a result are amplified in CA1. This would provide improved spatial memory in similar but different contexts.
43
Seel, Sabrina Vanessa. "The demands of episodic memory on hippocampal function in rats and humans." Thesis, Durham University, 2017. http://etheses.dur.ac.uk/12537/.
Full textAbstract:
This thesis sought to explore episodic memory, interference caused by similar events and its demands on hippocampal function by using different methodological and practical approaches in humans and rodents. Overall, this thesis focused on three aims, which included methodological approaches to testing episodic memory, using this approach to investigate cholinergic depletion of the hippocampus, and linking animal and human behavioural research. The recent development of spontaneous recognition tasks in rats to assess multiple trials consecutively in one testing session allow an opportunity to assess the role of contextual changes and interference in episodic memory. In a series of studies, it was shown that a new continuous trials apparatus can be used in behavioural as well as lesion studies to further explore the role of acetylcholine involved in episodic memory in rats without causing any proactive interference. Furthermore, the behavioural tasks in this thesis emphasise that context, which can take various forms, plays a profound role in segmenting memory of events. Whereas increasing the number of trials happening consecutively normally did not produce interference between events remembered, contextual representation within those trials was crucial. Chapters 2-7 demonstrated that depending on the context’s nature it enhances the segmentation of similar episodes and avoids interference, but it can also hinder recollection of events. Chapter 8 supplemented these findings by providing evidence in humans, where a clear deficit in recollection was found when a spatial change in a virtual environment was encountered, revealing a location updating effect. However, further validation of the human episodic memory task is necessary to make it a useful method in assessing different forms of hippocampal mechanisms involved in episodic memory.
44
Cush, Stephanie S. "Generation and Function of CD8 T Cell Memory to γ-Herpesviral Infection." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1290802468.
Full text
45
Roberts, Aaron. "The working memory function of authorised firearms officers during simulated armed confrontations." Thesis, University of Liverpool, 2012. http://livrepository.liverpool.ac.uk/6473/.
Full textAbstract:
This thesis examines the working memory (WM) function of authorised firearms officers (AFOs) after participation in a variety of simulated armed confrontations. In the UK, AFOs are required to operate and make decisions during situations in which there is a high degree of threat, novelty, time pressure, a large volume of perceptual information and a requirement to multi-task. A small amount of anecdotal evidence details the numerous perceptual distortions encountered by police officers in such situations. Whilst naturalistic decision making theories detail the cognitive heuristics employed by professionals who operate in comparable environments (e.g. fire fighters and military personnel), an investigation of the precise cognitive adaptations which occur during such demanding situations has not (to the knowledge of the researcher) been conducted. AFOs are required to use the conflict management model (CMM) to guide decision making; one of the main hypotheses in the present thesis is that the adequate use of the CMM requires Working Memory (WM) processing. As the multi-store model of WM is the accepted gold standard for behavioural experimentation; this was invoked as a template for the systematic examination of WM function in AFOs. To explore these issues, the researcher attended a variety of tactical training packages involving AFOs. In total over 200 training days were attended, including theoretical inputs. Discussions with firearms officers and their trainers facilitated the development of studies and subsequent interpretation of results. A total of 75 AFOs participated in 9 studies conducted around highly immersive simulated armed confrontations. Which were designed by firearms trainers to test AFOs tactic completion and decision making. A variety of standardised measures of WM function were sourced and administered to AFOs at various time points in relation to a simulated armed confrontation. This provided a body of work with high replicability and ecological validity. A variety of physiological measures were also collected, the rationale for which was as a test to establish if the simulated armed confrontations placed the anticipated level of demand on the officers. These measures were also used to make tentative inferences concerning the relationship between cognitive adaptations and physiological arousal which is well documented in the literature. The results suggest that the completion of tactics which are over learned (e.g. standard operating procedures) leads to a reduction in executive cognitive functioning whilst non-executive cognitive functioning simultaneously increases. It is reasonable to suggest that the available information processing capacity was devoted to following the standard operating procedure rather than making tactical decisions from scratch, hence the relative increase in non-executive functioning. The completion of novel and more complex tactics resulted in an increase in executive cognitive function whilst non-executive function decreased. It is also possible that the absence of experiential learning led to the allocation of information processing capacity to executive functioning in order to facilitate making novel tactical decisions in the absence of the ability to pattern match the cues from the environment. The demand placed on AFOs during a simulated armed confrontation appeared to lead to a shift in cognitive function. An increase in the processing of visuo-spatial information was observed, at the cost of phonological processing. The literature suggests this may represent a shift from left hemispheric cortical function to right hemispheric and more posterior activity. Information from two sources and particularly from different modalities cannot be simultaneously processed and attended to. In situations of high demand a faster speed of information processing and increased attention focus is achieved through decrease in PFC function. Attention is directed to the perceptual cue(s) most likely to facilitate with the coping/removing of the source of threat. It is suggested that these cognitive adaptations are defensive behaviours placing the officers in the optimum state to deal with the perceived threat. For example, the cognitive adaptations may reflect evolutionary responses to facilitate survival in situations of increased demand/threat. Hence these changes (even when decreases were observed) should not necessarily be viewed as deficits. Increases in physiological arousal demonstrated that the simulated armed confrontations placed increased demand on the AFOs resulting in a general adaptive response. Nevertheless, at all time points, in every test, performance was maintained at a relatively high level compared to control situations. The simulated armed confrontations conducted during the tactical training of authorised firearms officers provided a rare platform to investigate defensive behaviours in humans. The applications of the findings are discussed in terms of police training/policy, inputs to theory and methodological progress. It is also argued that, as well as demonstrating that defensive adaptations in humans result in cognitive shifts, more generally, the current studies may provide a foundation for the ethological study of human defensive behaviour.
46
Radpour, Shahrzad. "Electrophysiological studies of synaptic function in different regions of the hippocampus." Thesis, University of Southampton, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.278612.
Full text
47
Tourgeman, Isaac. "Exploration of the Wechsler Memory Scale Fourth Edition and Measures of Executive Function Combined Components Model." NSUWorks, 2015. http://nsuworks.nova.edu/cps_stuetd/86.
Full textAbstract:
While memory is the faculty that affords us learning, adaptation and development, it is our executive function that oversees, manages and organizes these abilities. Still, there is limited research on the interaction between memory and executive function. The present study investigated this relationship through Principal Components Analysis. Performances on accepted measures of memory and executive function were evaluated in an adult clinical sample. Components were retained using three criteria: a predetermined four-component structure, eigenvalues exceeding a value of one, and parallel analysis. Results demonstrated that a four-component model most accurately represented the data. Analyses also revealed that measures of immediate and delayed memory did not uniquely assess memory but instead loaded onto components associated with visual and verbal processing. The findings were shown to be in support of the brain working in an integrated, systematic manner in which abilities hierarchically ascend from arousal to tertiary function. Consequently, several accepted measures of memory and executive function failed to measure cognitive capacity unique from visual and verbal processing, placing their construct validity and efficacy in question.
48
Allen, Philip Andrew. "Secondary memory deficits as a function of increased processing variability in older adults /." The Ohio State University, 1987. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487326511714199.
Full text
49
Tanil, Cagatay. "Optimal External Configuration Design Of Missiles." Master's thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/12610873/index.pdf.
Full textAbstract:
The main area of emphasis in this study is to investigate the methods and technology for aerodynamic configuration sizing of missiles and to develop a software platform in MATLAB®environment as a design tool which has an ability of optimizing the external configuration of missiles for a set of flight requirements specified by the user through a graphical user interface. A genetic algorithm based optimization tool is prepared by MATLAB is expected to help the designer to find out the best external geometry candidates in the conceptual design stage. Missile DATCOM software package is employed to predict the aerodynamic coefficients needed in finding the performance merits of a missile for each external geometry candidate by integrating its dynamic equations of motion. Numerous external geometry candidates are rapidly eliminated according to objectives and constraints specified by designers, which provide necessary information in preliminary design. In this elimination, the external geometry candidates are graded according to their flight performances in order to discover an optimum solution. In the conceptual design, the most important performance objectives related to the external geometry of a missile are range, speed, maneuverability, and control effectiveness. These objectives are directly related to the equations of motion of the missile, concluding that the speed and flight range are related to the total mass and the drag-to-lift ratio acting on missile. Also, maneuverability depends on the normal force acting on missile body and mass whereas the control effectiveness is affected by pitching moment and mass moment of inertia of missile. All of the flight performance data are obtained by running a two degree-of-freedom simulation. In order to solve the resulting multi-objective optimization problem with a set of constraint of linear and nonlinear nature and in equality and inequality forms, genetic-algorithm-based methods are applied. Hybrid encoding methods in which the integer configuration variables (i.e., nose shape and control type) and real-valued geometrical dimension (i.e., diameter, length) parameters are encoded in the same individual chromosome. An external configuration design tool (EXCON) is developed as a synthesis and external sizing tool for the subsonic cruise missiles. A graphical user interface (GUI), a flight simulator and optimization modules are embedded into the tool. A numerical example, the re-configuration problem of an anti-ship cruise missile Harpoon, is presented to demonstrate the accuracy and feasibility of the conceptual design tool. The optimum external geometries found for different penalty weights of penalty terms in the cost function are compared according to their constraint violations and launch mass values. By means of using EXCON, the launch mass original baseline Harpoon is reduced by approximately 30% without deteriorating the other flight performance characteristics of the original Harpoon.
50
Tillman, Carin. "Working Memory and Higher-Order Cognition in Children." Doctoral thesis, Uppsala University, Department of Psychology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9271.
Full textAbstract:
Higher-order cognitive functions, such as executive function (EF) and intelligence, are crucial to the everyday functioning of human beings. Gaining knowledge about these functions is important for our general understanding of human nature as well as for our ability to help those who may not develop these processes optimally. The present thesis focused particularly on the EF component working memory (WM), described as the ability to maintain informa-tion in consciousness during short time periods with the purpose of using that information in complex cognition. The major aims of the thesis were to increase our understanding of higher-order cognition in children as well as of deficiencies in intelligence found in children with Attention Deficit Hyperactivity Disorder (ADHD). We approached these aims by studying the interrelations among EF-related components in terms of their independent contributions to intellectual functioning. We also studied whether the lower intelligence in children with ADHD was mediated by fundamental EF-related components or whether these deficiencies went beyond the weaknesses in these specific cognitive functions.
Interpreting the present data, we suggest that intellectual functioning in children is best viewed as representing a system of primarily independent parts that may be accompanied by an overarching common mechanism. The multiple components involve, but are surely not limited to, WM functions, inhibitory functions, sustained attention, and processing speed. One of these functions, WM, was found to be further partitioned into domain-specific executive WM processes and domain-specific short-term storage processes, all of which constitute important aspects of higher-order cognitive functioning. We have further learned that deficits in fluid intelligence in children with ADHD may entail more than weaknesses in specific central cognitive functions. This additional deficit is cautiously interpreted as involving supe-rior executive attention functions setting the stage for the development and integration of the EF system as well as the “intelligence system”.