A unified framework for linear function approximation of value functions in stochastic control

This paper contributes with a unified formulation that merges previ- ous analysis on the prediction of the performance ( value function ) of certain sequence of actions ( policy ) when an agent operates a Markov decision process with large state-space. When the states are represented by features and the value function is linearly approxi- mated, our analysis reveals a new relationship between two common cost functions used to obtain the optimal approximation. In addition, this analysis allows us to propose an efficient adaptive algorithm that provides an unbiased linear estimate. The performance of the pro- posed algorithm is illustrated by simulation, showing competitive results when compared with the state-of-the-art solutions.

Characterization of tomato Cycling Dof Factors reveals conserved and new functions in the control of flowering time and abiotic stress responses.

DNA binding with One Finger (DOF) transcription factors are involved in multiple aspects of plant growth and development but their precise roles in abiotic stress tolerance are largely unknown. Here we report a group of five tomato DOF genes, homologous to Arabidopsis Cycling DOF Factors (CDFs), that function as transcriptional regulators involved in responses to drought and salt stress and flowering-time control in a gene-specific manner. SlCDF1?5 are nuclear proteins that display specific binding with different affinities to canonical DNA target sequences and present diverse transcriptional activation capacities in vivo. SlCDF1?5 genes exhibited distinct diurnal expression patterns and were differentially induced in response to osmotic, salt, heat, and low-temperature stresses. Arabidopsis plants overexpressing SlCDF1 or SlCDF3 showed increased drought and salt tolerance. In addition, the expression of various stress-responsive genes, such as COR15, RD29A, and RD10, were differentially activated in the overexpressing lines. Interestingly, overexpression in Arabidopsis of SlCDF3 but not SlCDF1 promotes late flowering through modulation of the expression of flowering control genes such as CO and FT. Overall, our data connect SlCDFs to undescribed functions related to abiotic stress tolerance and flowering time through the regulation of specific target genes and an increase in particular metabolites

A Structure of Problem Solving Methods for Real Time Decision Support in Traffic Control

This article describes a knowledge-based application in the domain of road traffic management that we have developed following a knowledge modeling approach and the notion of problem-solving method. The article presents first a domain-independent model for real-time decision support as a structured collection of problem solving methods. Then, it is described how this general model is used to develop an operational version for the domain of traffic management. For this purpose, a particular knowledge modeling tool, called KSM (Knowledge Structure Manager), was applied. Finally, the article shows an application developed for a traffic network of the city of Madrid and it is compared with a second application developed for a different traffic area of the city of Barcelona.

The role of the synthetic enzyme GAD65 in the control of neuronal γ-aminobutyric acid release

We have studied GABAergic synaptic transmission in retinal ganglion cells and hippocampal pyramidal cells to determine, at a cellular level, what is the effect of the targeted disruption of the gene encoding the synthetic enzyme GAD65 on the synaptic release of γ-aminobutyric acid (GABA). Neither the size nor the frequency of GABA-mediated spontaneous inhibitory postsynaptic currents (IPSCs) were reduced in retina or hippocampus in GAD65−/− mice. However, the release of GABA during sustained synaptic activation was substantially reduced. In the retina both electrical- and K+-induced increases in IPSC frequency were depressed without a change in IPSC amplitude. In the hippocampus the transient increase in the probability of inhibitory transmitter release associated with posttetanic potentiation was absent in the GAD65−/− mice. These results indicate that during and immediately after sustained stimulation the increase in the probability of transmitter release is not maintained in GAD65−/− mice. Such a finding suggests a decrease in the size or refilling kinetics of the releasable pool of vesicles, and various mechanisms are discussed that could account for such a defect.

Nitric oxide plays a key role in adaptive control of locomotion in cat

Diverse roles in cellular functions have been ascribed to nitric oxide (NO), and its involvement in induction of long-term depression in cerebellar Purkinje cells has been demonstrated. Manipulations of NO concentration or its synthesis in cerebellar tissues therefore provide a means for investigating roles of NO in cerebellar functions at both cellular and behavioral levels. We tested adaptive control of locomotion to perturbation in cats, and found that this form of motor learning was abolished by application of either an inhibitor of NO synthase or a scavenger of NO to the cerebellar cortical locomotion area. This finding supports the view that NO in the cerebellum plays a key role in motor learning.

Integrin-mediated Adhesion of Endothelial Cells Induces JAK2 and STAT5A Activation: Role in the Control of c-fos Gene Expression

Integrin-mediated adhesion induces several signaling pathways leading to regulation of gene transcription, control of cell cycle entry and survival from apoptosis. Here we investigate the involvement of the Janus kinase (JAK)/signal transducers and activators of transcription (STAT) pathway in integrin-mediated signaling. Plating primary human endothelial cells from umbilical cord and the human endothelial cell line ECV304 on matrix proteins or on antibody to β1- or αv-integrin subunits induces transient tyrosine phosphorylation of JAK2 and STAT5A. Consistent with a role for the JAK/STAT pathway in regulation of gene transcription, adhesion to matrix proteins leads to the formation of STAT5A-containing complexes with the serum-inducible element of c-fos promoter. Stable expression of a dominant negative form of STAT5A in NIH3T3 cells reduces fibronectin-induced c-fos mRNA expression, indicating the involvement of STAT5A in integrin-mediated c-fos transcription. Thus these data present a new integrin-dependent signaling mechanism involving the JAK/STAT pathway in response to cell–matrix interaction.

Identification of metabolic pathways of brain angiotensin II and III using specific aminopeptidase inhibitors: predominant role of angiotensin III in the control of vasopressin release.

Angiotensin (Ang) II and Ang III are two peptide effectors of the brain renin-angiotensin system that participate in the control of blood pressure and increase water consumption and vasopressin release. In an attempt to delineate the respective roles of these peptides in the regulation of vasopressin secretion, their metabolic pathways and their effects on vasopressin release were identified in vivo. For this purpose, we used recently developed selective inhibitors of aminopeptidase A (APA) and aminopeptidase N (APN), two enzymes that are believed to be responsible for the N-terminal cleavage of Ang II and Ang III, respectively. Mice received [3H]Ang II intracerebroventricularly (i.c.v.) in the presence or absence of the APN inhibitor, EC33 (3-amino-4-thio-butyl sulfonate) of the APN inhibitor, EC27 (2-amino-pentan-1,5-dithiol). [3H]Ang II and [3H]Ang III levels were evaluated from hypothalamus homogenates by HPLC. EC33 increased the half-life of [3H]Ang II 2.6-fold and completely blocked the formation of [3H]Ang III, whereas EC27 increased the half-life of [3H]Ang III 2.3-fold. In addition, the effects of EC33 and EC27 on Ang-induced vasopressin release were studied in mice. Ang II was injected i.c.v. in the presence or absence of EC33, and plasma vasopressin levels were estimated by RIA. While vasopressin levels were increased 2-fold by Ang II (5 ng), EC33 inhibited Ang II-induced vasopressin release in a dose-dependent manner. In contrast, EC27 injected alone increased in a dose-dependent manner vasopressin levels. The EC27-induced vasopressin release was completely blocked by the coadministration of the Ang receptor antagonist (Sar1-Ala8) Ang II. These results demonstrate for the first time that (i) APA and APN are involved in vivo in the metabolism of brain Ang II and Ang III, respectively, and that (ii) the action of Ang II on vasopressin release depends upon the prior conversion of Ang II to Ang III. This shows that Ang III behaves as one of the main effector peptides of the brain renin-angiotensin system in the control of vasopressin release.

Cellular strategies for accommodating replication-hindering adducts in DNA: control by the SOS response in Escherichia coli.

The replication of double-stranded plasmids containing a single adduct was analyzed in vivo by means of a sequence heterology that marks the two DNA strands. The single adduct was located within the sequence heterology, making it possible to distinguish trans-lesion synthesis (TLS) events from damage avoidance events in which replication did not proceed through the lesion. When the SOS system of the host bacteria is not induced, the C8-guanine adduct formed by the carcinogen N-2-acetylaminofluorene (AAF) yields less than 1% of TLS events, showing that replication does not readily proceed through the lesion. In contrast, the deacetylated adduct N-(deoxyguanosin-8-yl)-2-aminofluorene yields approximately 70% of TLS events under both SOS-induced and uninduced conditions. These results for TLS in vivo are in good agreement with the observation that AAF blocks DNA replication in vitro, whereas aminofluorene does so only weakly. Induction of the SOS response causes an increase in TLS events through the AAF adduct (approximately 13%). The increase in TLS is accompanied by a proportional increase in the frequency of AAF-induced frameshift mutations. However, the polymerase frameshift error rate per TLS event was essentially constant throughout the SOS response. In an SOS-induced delta umuD/C strain, both US events and mutagenesis are totally abolished even though there is no decrease in plasmid survival. Error-free replication evidently proceeds efficiently by means of the damage avoidance pathway. We conclude that SOS mutagenesis results from increased TLS rather than from an increased frameshift error rate of the polymerase.

Creation of a reversible on/off system for site-specific in vivo control of exogenous gene activity in the renal glomerulus.

Using genetically engineered glomerular mesangial cells, an in vivo gene transfer approach was developed that specifically targets the renal glomerulus. By combining this system with a tetracycline (Tc)-responsive promoter, the present study aimed to create a reversible on/off system for site-specific in vivo control of exogenous gene activity within the glomerulus. In the Tc regulatory system, a Tc-controlled transactivator (tTA) encoded by a regulator plasmid induces target gene transcription by binding to a tTA-responsive promoter located in a response plasmid. Tc inhibits this tTA-dependent transactivation via its affinity for tTA. In double-transfected cells, therefore, the activity of a transgene can be controlled by Tc. Cultured rat mesangial cells were cotransfected with a regulator plasmid and a response plasmid that introduces a beta-galactosidase gene. In vitro, stable double-transfectant MtTAG cells exhibited no beta-galactosidase activity in the presence of Tc. However, following withdrawal of Tc from culture media, expression of beta-galactosidase was induced within 24 h. When Tc was again added, the expression was rapidly resuppressed. Low concentrations of Tc were sufficient to maintain the silent state of tTA-dependent promoter. MtTAG cells were then transferred into the rat glomeruli via renal artery injection. In the isolated chimeric glomeruli, expression of beta-galactosidase was induced ex vivo in the absence of Tc, whereas it was repressed in its presence. When Tc-pretreated MtTAG cells were transferred into the glomeruli of untreated rats, beta-galactosidase expression was induced in vivo within 3 days. Oral administration of Tc dramatically suppressed this induction. These data demonstrate the feasibility of using mesangial cell vectors combined with the Tc regulatory system for site-specific in vivo control of exogenous gene expression in the glomerulus.

Countermanding in rats as a practical model for investigation of adaptive control of behaviour, lifespan changes in behavioural control and neurotransmitter function

The countermanding paradigm was designed to investigate the ability to cancel a prepotent response when a stop signal is presented and allows estimation of the stop signal response time (SSRT), an otherwise unobservable behaviour. Humans exhibit adaptive control of behaviour in the countermanding task, proactively lengthening response time (RT) in expectation of stopping and reactively lengthening RT following stop trials or errors. Human performance changes throughout the lifespan, with longer RT, SSRT and greater emphasis on post-error slowing reported for older compared to younger adults. Inhibition in the task has generally been improved by drugs that increase extracellular norepinephrine. The current thesis examined a novel choice response countermanding task in rats to explore whether rodent countermanding performance is a suitable model for the study of adaptive control of behaviour, lifespan changes in behavioural control and the role of neurotransmitters in these behaviours. Rats reactively adjusted RT in the countermanding task, shortening RT after consecutive correct go trials and lengthening RT following non-cancelled, but not cancelled stop trials, in sessions with a 10 s, but not a 1 s post-error timeout interval. Rats proactively lengthened RT in countermanding task sessions compared to go trial-only sessions. Together, these findings suggest that rats strategically lengthened RT in the countermanding task to improve accuracy and avoid longer, unrewarded timeout intervals. Next, rats exhibited longer RT and relatively conserved post-error slowing, but no significant change in SSRT when tested at 12, compared to 7 months of age, suggesting that rats exhibit changes in countermanding task performance with aging similar to those observed in humans. Finally, acute administration of yohimbine (1.25, 2.5 mg/kg) and d-amphetamine (0.25, 0.5 mg/kg), which putatively increase extracellular norepinephrine and dopamine respectively, resulted in RT shortening, baseline-dependent effects on SSRT, and attenuated adaptive RT adjustments in rats in the case of d-amphetamine. These findings suggest that dopamine and norepinephrine encouraged motivated, reward-seeking behaviour and supported inhibitory control in an inverted-U-like fashion. Taken together, these observations validate the rat countermanding task for further study of the neural correlates and neurotransmitters mediating adaptive control of behaviour and lifespan changes in behavioural control.

National accomplishments in pollution control, 1970-1980 : some case histories /

Mode of access: Internet.

Pressure tests in flood-control conduit, Melvern Dam, Kansas : final report /

Issued May 1977.

Ohio's interest in flood control : position of the Ohio chamber of commerce in re regional "authorities" bills, presented by Karl S. Dixon secretary of the Chamber's Action committee on flood control to the House Committee on rivers and harbors, Washington, D.C., July 21, 1937.

Cover-title.

Trespass handbook : for the use and guidance of employees of the Bureau of Land Management in the control of trespass on the public lands.

"April 1950."