Use of antenatal corticosteroids and tocolytic drugs in preterm births in 29 countries: an analysis of the WHO Multicountry Survey on Maternal and Newborn Health.

PubMed

Vogel, Joshua P; Souza, João Paulo; Gülmezoglu, A Metin; Mori, Rintaro; Lumbiganon, Pisake; Qureshi, Zahida; Carroli, Guillermo; Laopaiboon, Malinee; Fawole, Bukola; Ganchimeg, Togoobaatar; Zhang, Jun; Torloni, Maria Regina; Bohren, Meghan; Temmerman, Marleen

2014-11-22

Despite the global burden of morbidity and mortality associated with preterm birth, little evidence is available for use of antenatal corticosteroids and tocolytic drugs in preterm births in low-income and middle-income countries. We analysed data from the WHO Multicountry Survey on Maternal and Newborn Health (WHOMCS) to assess coverage for these interventions in preterm deliveries. WHOMCS is a facility-based, cross-sectional survey database of birth outcomes in 359 facilities in 29 countries, with data collected prospectively from May 1, 2010, to Dec 31, 2011. For this analysis, we included deliveries after 22 weeks' gestation and we excluded births that occurred outside a facility or quicker than 3 h after arrival. We calculated use of antenatal corticosteroids in women who gave birth between 26 and 34 weeks' gestation, when antenatal corticosteroids are known to be most beneficial. We also calculated use in women at 22-25 weeks' and 34-36 weeks' gestation. We assessed tocolytic drug use, with and without antenatal corticosteroids, in spontaneous, uncomplicated preterm deliveries at 26-34 weeks' gestation. Of 303,842 recorded deliveries after 22 weeks' gestation, 17,705 (6%) were preterm. 3900 (52%) of 7547 women who gave birth at 26-34 weeks' gestation, 94 (19%) of 497 women who gave birth at 22-25 weeks' gestation, and 2276 (24%) of 9661 women who gave birth at 35-36 weeks' gestation received antenatal corticosteroids. Rates of antenatal corticosteroid use varied between countries (median 54%, range 16-91%; IQR 30-68%). Of 4677 women who were potentially eligible for tocolysis drugs, 1276 (27%) were treated with bed rest or hydration and 2248 (48%) received no treatment. β-agonists alone (n=346, 7%) were the most frequently used tocolytic drug. Only 848 (18%) of potentially eligible women received both a tocolytic drug and antenatal corticosteroids. Use of interventions was generally poor, despite evidence for their benefit for newborn babies. A substantial proportion of antenatal corticosteroid use occurred at gestational ages at which benefit is controversial, and use of less effective or potentially harmful tocolytic drugs was common. Implementation research and contextualised health policies are needed to improve drug availability and increase compliance with best obstetric practice. UNDP-UNFPA-UNICEF-WHO-World Bank Special Programme of Research, Development and Research Training in Human Reproduction (HRP); WHO; USAID; Ministry of Health, Labour and Welfare of Japan; Gynuity Health Projects. Copyright © 2014 World Health Organization. Published by Elsevier Ltd/Inc/BV. All rights reserved. Published by Elsevier Ltd. All rights reserved.

Ethanol for preventing preterm birth in threatened preterm labor.

PubMed

Haas, David M; Morgan, Amanda M; Deans, Samantha J; Schubert, Frank P

2015-11-05

Preterm birth is the leading cause of death and disability in newborns worldwide. A wide variety of tocolytic agents have been utilized to delay birth for women in preterm labor. One of the earliest tocolytics utilized for this purpose was ethanol infusion, although this is not generally used in current practice due to safety concerns for both the mother and her baby. To determine the efficacy of ethanol in stopping preterm labor, preventing preterm birth, and the impact of ethanol on neonatal outcomes. We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 May 2015) and reference lists of retrieved studies. We included randomized and quasi-randomized studies. Cluster-randomized trials and cross-over design trials were not eligible for inclusion. We only included studies published in abstract form if there was enough information on methods and relevant outcomes. Trials were included if they compared ethanol infusion to stop preterm labor versus placebo/control or versus other tocolytic drugs. At least two review authors independently assessed studies for inclusion and risk of bias. At least two review authors independently extracted data. Data were checked for accuracy. Twelve trials involving 1586 women met inclusion criteria for this review. One trial did not report on the outcomes of interest in this review.Risk of bias of included studies: The included studies generally were of low quality based on inadequate reporting of methodology. Only three trials had low risk of bias for random sequence generation and one had low risk of bias for allocation concealment and participant blinding. Most studies were either high risk of bias or uncertain in these key areas. Comparison 1: Ethanol versus placebo/control (two trials, 77 women) Compared to controls receiving pain medications and dextrose solution, ethanol did not improve any of the primary outcomes: birth < 48 hours after trial entry (one trial, 35 women; risk ratio (RR) 0.93, 95% confidence interval (CI) 0.43 to 2.00), or neonatal mortality (one trial, 35 women; RR 1.06, 95% CI 0.31 to 3.58). Serious maternal adverse events and perinatal mortality were not reported by either of the two trials in this comparison. Maternal adverse events (overall) were not reported but one trial (42 women) reported that there were no maternal adverse events that required stopping or changing drug) in either group. One trial did report delay until delivery but this outcome was reported as a median with no mention of the standard deviation (median 19 days in ethanol group versus "less than 1" day in the glucose/water group). There were no differences in any secondary outcomes reported: preterm birth < 34 weeks or < 37 weeks; serious infant outcome; fetal alcohol syndrome/fetal alcohol spectrum disorder; or small-for-gestational age. Comparison 2: Ethanol versus other tocolytic (betamimetics) (nine trials, 1438 women) Compared to betamimetics (the only tocolytic used as a comparator in these studies), ethanol was associated with no clear difference in the rate of birth < 48 hours after trial entry (two trials, 130 women; average RR 1.12, 95% CI 0.53 to 2.37, Tau² = 0.19, I² = 59%), similar rates of perinatal mortality (six trials, 698 women; RR1.20, 95% CI 0.78 to 1.84), higher rates of neonatal mortality (eight trials, 1238 women; RR 1.43, 95% CI 1.02 to 2.02), higher rates of preterm birth < 34 weeks (two trials, 599 women; RR 1.56, 95% CI 1.11 to 2.19), higher rates of neonatal respiratory distress syndrome (three trials, 823 women; RR 1.76, 95% CI 1.33 to 2.33), and higher rates of low birthweight babies < 2500 g (five trials, 834 women; RR 1.30, 95% CI 1.09 to 1.54). These outcomes are likely all related to the lower incidence of preterm birth seen with other tocolytics, which for all these comparisons were betamimetics. Serious maternal adverse events were not reported in any of the nine trial reports. However, ethanol had a trend towards a lower rate of maternal adverse events requiring stopping or changing the drug (three trials, 214 women; RR 0.25, 95% CI 0.06 to 0.97). There were no differences in other secondary outcomes of preterm birth < 37 weeks, number of days delivery was delayed, or overall maternal adverse events.Planned sensitivity analysis, excluding quasi-randomized trials did not substantially change the results of the primary outcome analyses with the exception of neonatal mortality which no longer showed a clear difference between the ethanol and other tocolytic groups (3 trials, 330 women; RR 1.49, 95% CI 0.82 to 2.72). This review is based on evidence from twelve studies which were mostly low quality. There is no evidence that to suggest that ethanol is an effective tocolytic compared to placebo. There is some evidence that ethanol may be better tolerated than other tocolytics (in this case betamimetics), but this result is based on few studies and small sample size and therefore should be interpreted with caution. Ethanol appears to be inferior to betamimetics for preventing preterm birth in threatened preterm labor.Ethanol is generally no longer used in current practice due to safety concerns for the mother and her baby. There is no need for new studies to evaluate the use of ethanol for preventing preterm birth in threatened preterm labour. However, it would be useful for long-term follow-up studies on the babies born to mothers from the existing studies in order to assess the risk of long-term neurodevelopmental status.

Mind the information gap: fertility rate and use of cesarean delivery and tocolytic hospitalizations in Taiwan.

PubMed

Ma, Ke-Zong M; Norton, Edward C; Lee, Shoou-Yih D

2011-12-12

Physician-induced demand (PID) is an important theory to test given the longstanding controversy surrounding it. Empirical health economists have been challenged to find natural experiments to test the theory because PID is tantamount to strong income effects. The data requirements are both a strong exogenous change in income and two types of treatment that are substitutes but have different net revenues. The theory implies that an exogenous fall in income would lead physicians to recoup their income by substituting a more expensive treatment for a less expensive treatment. This study takes advantages of the dramatic decline in the Taiwanese fertility rate to examine whether an exogenous and negative income shock to obstetricians and gynecologists (ob/gyns) affected the use of c-sections, which has a higher reimbursement rate than vaginal delivery under Taiwan's National Health Insurance system during the study period, and tocolytic hospitalizations. The primary data were obtained from the 1996 to 2004 National Health Insurance Research Database in Taiwan. We hypothesized that a negative income shock to ob/gyns would cause them to provide more c-sections and tocolytic hospitalizations to less medically-informed pregnant women. Multinomial probit and probit models were estimated and the marginal effects of the interaction term were conducted to estimate the impacts of ob/gyn to birth ratio and the information gap. Our results showed that a decline in fertility did not lead ob/gyns to supply more c-sections to less medically-informed pregnant women, and that during fertility decline ob/gyns may supply more tocolytic hospitalizations to compensate their income loss, regardless of pregnant women's access to health information. The exogenous decline in the Taiwanese fertility rate and the use of detailed medical information and demographic attributes of pregnant women allowed us to avoid the endogeneity problem that threatened the validity of prior research. They also provide more accurate estimates of PID.JEL Classification: I10, I19, C23, C25.

The Evidence Regarding Maintenance Tocolysis

PubMed Central

Elliott, John P.; Morrison, John C.

2013-01-01

Preterm delivery is a public health issue of major proportion. More than 12% of deliveries in the United States that occur at less than 37 weeks gestation preterm labor (PTL) represents the largest single reason for preterm birth (PTB). Attempts to prevent PTB have been unsuccessful. This paper of maintenance tocolytic therapy will examine the efficacy and safety of the drugs, both oral and subcutaneous, which have been utilized for prolongation of pregnancy following successful arrest of a documented episode of acute preterm labor. The evidence for oral tocolytics as maintenance therapy as well as parenteral medications for such patients is offered. Finally, the effects in the United States of the Food and Drug Administration (FDA) action on such medications are reported. PMID:23577034

Calcium channel blockers for inhibiting preterm labour and birth.

PubMed

Flenady, Vicki; Wojcieszek, Aleena M; Papatsonis, Dimitri N M; Stock, Owen M; Murray, Linda; Jardine, Luke A; Carbonne, Bruno

2014-06-05

Preterm birth is a major contributor to perinatal mortality and morbidity, affecting around 9% of births in high-income countries and an estimated 13% of births in low- and middle-income countries. Tocolytics are drugs used to suppress uterine contractions for women in preterm labour. The most widely used tocolytic are the betamimetics, however, these are associated with a high frequency of unpleasant and sometimes severe maternal side effects. Calcium channel blockers (CCBs) (such as nifedipine) may have similar tocolytic efficacy with less side effects than betamimetics. Oxytocin receptor antagonists (ORAs) (e.g. atosiban) also have a low side-effect profile. To assess the effects on maternal, fetal and neonatal outcomes of CCBs, administered as a tocolytic agent, to women in preterm labour. We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (12 November 2013). All published and unpublished randomised trials in which CCBs were used for tocolysis for women in labour between 20 and 36 completed weeks' gestation. Two review authors independently assessed trial eligibility, undertook quality assessment and data extraction. Results are presented using risk ratio (RR) for categorical data and mean difference (MD) for data measured on a continuous scale with the 95% confidence interval (CI). The number needed to treat to benefit (NNTB) and the number needed to treat to harm (NNTH) were calculated for categorical outcomes that were statistically significantly different. This update includes 26 additional trials involving 2511 women, giving a total of 38 included trials (3550 women). Thirty-five trials used nifedipine as the CCB and three trials used nicardipine. Blinding of intervention and outcome assessment was undertaken in only one of the trials (a placebo controlled trial). However, objective outcomes defined according to timing of birth and perinatal mortality were considered to have low risk of detection bias.Two small trials comparing CCBs with placebo or no treatment showed a significant reduction in birth less than 48 hours after trial entry (RR 0.30, 95% CI 0.21 to 0.43) and an increase in maternal adverse effects (RR 49.89, 95% CI 3.13 to 795.02, one trial of 89 women). Due to substantial heterogeneity, outcome data for preterm birth (less than 37 weeks) were not combined; one placebo controlled trial showed no difference (RR 0.96, 95% CI 0.89 to 1.03) while the other (non-placebo controlled trial) reported a reduction (RR 0.44, 95% CI 0.31 to 0.62). No other outcomes were reported.Comparing CCBs (mainly nifedipine) with other tocolytics by type (including betamimetics, glyceryl trinitrate (GTN) patch, non-steriodal anti inflammatories (NSAID), magnesium sulphate and ORAs), no significant reductions were shown in primary outcome measures of birth within 48 hours of treatment or perinatal mortality.Comparing CCBs with betamimetics, there were fewer maternal adverse effects (average RR 0.36, 95% CI 0.24 to 0.53) and fewer maternal adverse effects requiring discontinuation of therapy (average RR 0.22, 95% CI 0.10 to 0.48). Calcium channel blockers resulted in an increase in the interval between trial entry and birth (average MD 4.38 days, 95% CI 0.25 to 8.52) and gestational age (MD 0.71 weeks, 95% CI 0.34 to 1.09), while decreasing preterm and very preterm birth (RR 0.89, 95% CI 0.80 to 0.98 and RR 0.78, 95% CI 0.66 to 0.93); respiratory distress syndrome (RR 0.64, 95% CI 0.48 to 0.86); necrotising enterocolitis (RR 0.21, 95% CI 0.05 to 0.96); intraventricular haemorrhage (RR 0.53, 95% CI 0.34 to 0.84); neonatal jaundice (RR 0.72, 95% CI 0.57 to 0.92); and admissions to neonatal intensive care unit (NICU) (average RR 0.74, 95% CI 0.63 to 0.87). No difference was shown in one trial of outcomes at nine to twelve years of age.Comparing CCBs with ORA, data from one study (which did blind the intervention) showed an increase in gestational age at birth (MD 1.20 completed weeks, 95% CI 0.25 to 2.15) and reductions in preterm birth (RR 0.64, 95% CI 0.47 to 0.89); admissions to the NICU (RR 0.59, 95% CI 0.41 to 0.85); and duration of stay in the NICU (MD -5.40 days,95% CI -10.84 to 0.04). Maternal adverse effects were increased in the CCB group (average RR 2.61, 95% CI 1.43 to 4.74).Comparing CCBs with magnesium sulphate, maternal adverse effects were reduced (average RR 0.52, 95% CI 0.40 to 0.68), as was duration of stay in the NICU (days) (MD -4.55, 95% CI -8.17 to -0.92). No differences were shown in the comparisons with GTN patch or NSAID, although numbers were small.No differences in outcomes were shown in trials comparing nicardipine with other tocolytics, although with limited data no strong conclusions can be drawn. No differences were evident in a small trial that compared higher- versus lower-dose nifedipine, though findings tended to favour a high dose on some measures of neonatal morbidity. Calcium channel blockers (mainly nifedipine) for women in preterm labour have benefits over placebo or no treatment in terms of postponement of birth thus, theoretically, allowing time for administration of antenatal corticosteroids and transfer to higher level care. Calcium channel blockers were shown to have benefits over betamimetics with respect to prolongation of pregnancy, serious neonatal morbidity, and maternal adverse effects. Calcium channel blockers may also have some benefits over ORAs and magnesium sulphate, although ORAs results in fewer maternal adverse effects. However, it must be noted that no difference was shown in perinatal mortality, and data on longer-term outcomes were limited. Further, the lack of blinding of the intervention diminishes the strength of this body of evidence. Further well-designed tocolytic trials are required to determine short- and longer-term infant benefit of CCBs over placebo or no treatment and other tocolytics, particularly ORAs. Another important focus for future trials is identifying optimal dosage regimens of different types of CCBs (high versus low, particularly addressing speed of onset of uterine quiescence) and formulation (capsules versus tablets). All future trials on tocolytics for women in preterm labour should employ blinding of the intervention and outcome assessment, include measurement of longer-term effects into early childhood, and also costs.

Mind the information gap: fertility rate and use of cesarean delivery and tocolytic hospitalizations in Taiwan

PubMed Central

2011-01-01

Background Physician-induced demand (PID) is an important theory to test given the longstanding controversy surrounding it. Empirical health economists have been challenged to find natural experiments to test the theory because PID is tantamount to strong income effects. The data requirements are both a strong exogenous change in income and two types of treatment that are substitutes but have different net revenues. The theory implies that an exogenous fall in income would lead physicians to recoup their income by substituting a more expensive treatment for a less expensive treatment. This study takes advantages of the dramatic decline in the Taiwanese fertility rate to examine whether an exogenous and negative income shock to obstetricians and gynecologists (ob/gyns) affected the use of c-sections, which has a higher reimbursement rate than vaginal delivery under Taiwan's National Health Insurance system during the study period, and tocolytic hospitalizations. Methods The primary data were obtained from the 1996 to 2004 National Health Insurance Research Database in Taiwan. We hypothesized that a negative income shock to ob/gyns would cause them to provide more c-sections and tocolytic hospitalizations to less medically-informed pregnant women. Multinomial probit and probit models were estimated and the marginal effects of the interaction term were conducted to estimate the impacts of ob/gyn to birth ratio and the information gap. Results Our results showed that a decline in fertility did not lead ob/gyns to supply more c-sections to less medically-informed pregnant women, and that during fertility decline ob/gyns may supply more tocolytic hospitalizations to compensate their income loss, regardless of pregnant women's access to health information. Conclusion The exogenous decline in the Taiwanese fertility rate and the use of detailed medical information and demographic attributes of pregnant women allowed us to avoid the endogeneity problem that threatened the validity of prior research. They also provide more accurate estimates of PID. JEL Classification: I10, I19, C23, C25 PMID:22828182

Effect of Bryophyllum pinnatum versus fenoterol on uterine contractility.

PubMed

Gwehenberger, Birgit; Rist, Lukas; Huch, Renate; von Mandach, Ursula

2004-04-15

To characterise the phytotherapeutic tocolytic Bryophyllum pinnatum in vitro versus the conventional betamimetic, fenoterol, in human myometrium. Contractility (endpoints: area under the curve (AUC), amplitude and frequency of isometric force development) was measured in strips of term myometrium biopsied at caesarean section in 14 women and exposed to increasing concentrations of B. pinnatum versus +/- oxytocin 1 U/l. Inhibition of spontaneous contraction by B. pinnatum was concentration-dependent: 16% at maximum concentration (10(4) mg/l), or 53% that with fenoterol 5 x 10(-8)mol/l. B. pinnatum increased contraction frequency by 91% at constant amplitude and inhibited oxytocin-stimulated contractions by 20% (AUC) at constant amplitude with slightly decreased frequency. Fenoterol decreased contraction AUC by 50% with a significant decrease in frequency. Our in vitro data confirm the tocolytic activity of B. pinnatum observed in alternative medicine centres and may justify further clinical studies.

Comparison of CRP and ALK-P serum levels in prediction of preterm delivery

PubMed Central

Shahshahan, Zahra; Iravani, Hoda

2016-01-01

Background: Preterm birth, defined as birth occurring before 37 weeks of gestation, is a common complication of pregnancy and may lead to death or long-term disability in newborns. Accurate diagnosis is, therefore, crucial for identifying those women undergoing preterm labor who are at greatest risk of preterm delivery. This may allow transport to a regional obstetrical center and permit time for corticosteroid therapy. Recent study recommends several markers such as CRP (C-reactive protein) and ALK-P (alkaline phosphatase) to predict preterm delivery. Materials and Methods: We select a total of 300 pregnant women that had symptoms of premature birth. All of them were under treatment with tocolytic and serum sample were taken to assess the level of CRP-ALKp. Cervix length and the time of response to tocolytic were measured. 110 pregnant of them had preterm labor. 110 patient that had a term labor selected as a control group. Results: Qualitative evaluation of efficacy CRP level on preterm delivery showed a significant relationship with 27 as a cut of point of CRP (P < 0.00001 –OR = 7.5). Investigate of effect of ALK-P level on preterm delivery refers to a significant relationship with 399 as a cut of point of ALKP (P < 0.00001 –OR = 5). Inquire of efficacy of CRP level and ALK-P level on preterm delivery demonstrate a significant relationship (P < 0.0001 1OR = 9). Conclusions: Maternal concentrations of CRP and ALKP and cervix length can be used as appropriate biomarker for predicting preterm labor and response to tocolytic therapy in pregnant women. PMID:26962519

Tocolysis for management of retained placenta.

PubMed

Abdel-Aleem, Hany; Abdel-Aleem, Mahmoud A; Shaaban, Omar M

2011-01-19

Retained placenta affects 0.5% to 3% of women following delivery, with considerable morbidity if left untreated. Use of tocolytics, either alone or in combination with uterotonics, may be of value to minimise the need for manual removal of the placenta in theatre under anaesthesia. Evaluate the benefits and harms of tocolytics alone or in addition to uterotonics in the management of retained placenta in order to reduce the need for manual removal of placenta. We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 October 2010) and contacted experts in the field. Any adequately randomised controlled trial (RCT) comparing the use of tocolytics, either alone or in combination with uterotonics, with no intervention or with other interventions in the management of retained placenta. All women having a vaginal delivery with a retained placenta, regardless of the management of the third stage of labour (expectant or active). We included all trials with haemodynamically stable women in whom the placenta was not delivered at least within 15 minutes after delivery of the baby. Two review authors independently assessed trial quality and extracted data. Consultation of the third author was done if needed. We included one RCT (involving 24 women). It compared the use of nitroglycerin tablets versus placebo after the treatment with oxytocin failed. There was a statistically significant reduction in the need for manual removal of placenta (risk ratio (RR) 0.04, 95% confidence interval (CI) 0.00 to 0.66). There was also a statistically significant reduction in mean blood loss during the third stage of labour (mean difference (MD) -262.50 ml, 95% CI -364.95 to -160.05). Sublingual nitroglycerin caused some haemodynamic changes as it lowers the systolic blood pressure and diastolic blood pressure by a means of 6 and 5 mmHg respectively. Pulse rate increased by a mean of two beats per minute. Sublingual nitroglycerin, given when oxytocin fails, seems to reduce both the need for manual removal of placenta and blood loss during the third stage of labour when compared to placebo. Further trials are needed to confirm its clinical role and safety. Its routine use cannot be recommended based on a single small study. There is no evidence available for other types of tocolytics.

Developmental exposure to terbutaline and chlorpyrifos: pharmacotherapy of preterm labor and an environmental neurotoxicant converge on serotonergic systems in neonatal rat brain regions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aldridge, Justin E.; Meyer, Armando; Centro de Estudos da Saude do Trabalhador e Ecologia Humana, Escola Nacional de Saude Publica, Fundacao Oswaldo Cruz, Rio de Janeiro

2005-03-01

Developmental exposure to unrelated neurotoxicants can nevertheless produce similar neurobehavioral outcomes. We examined the effects of developmental exposure to terbutaline, a tocolytic {beta}{sub 2}-adrenoceptor agonist used to arrest preterm labor, and chlorpyrifos (CPF), a widely used organophosphate pesticide, on serotonin (5HT) systems. Treatments were chosen to parallel periods typical of human developmental exposures, terbutaline (10 mg/kg) on postnatal days (PN) 2-5 and CPF (5 mg/kg) on PN11-14, with assessments conducted on PN45, comparing each agent alone as well as sequential administration of both. Although neither treatment affected growth or viability, each elicited similar alterations in factors that are critical tomore » the function of the 5HT synapse: 5HT{sub 1A} receptors, 5HT{sub 2} receptors, and the presynaptic 5HT transporter (5HTT). Either agent elicited global increases in 5HT receptors and the 5HTT in brain regions possessing 5HT cell bodies (midbrain, brainstem) as well as in the hippocampus, which contains 5HT projections. For both terbutaline and CPF, males were affected more than females, although there were some regional disparities in the sex selectivity between the two agents. Both altered 5HT receptor-mediated cell signaling, suppressing stimulatory effects on adenylyl cyclase and enhancing inhibitory effects. When animals were exposed sequentially to both agents, the outcomes were no more than additive and, for many effects, less than additive, suggesting convergence of the two agents on a common set of developmental mechanisms. Our results indicate that 5HT systems represent a target for otherwise unrelated neuroteratogens.« less

5β-Reduced Steroids and Human Δ4-3-Ketosteroid 5β-Reductase (AKR1D1)

PubMed Central

Chen, Mo; Penning, Trevor M.

2014-01-01

5β-Reduced steroids are non-planar steroids that have 90° bend in their structure to create an A/B cis-ring junction. This novel property is required for bile-acids to act as emulsifiers, but in addition 5β-reduced steroids have remarkable physiology and may act as potent tocolytic agents, endogenous cardiac glycosides, neurosteroids, and can act as ligands for orphan and membrane bound receptors. In humans there is only a single 5β-reductase gene AKR1D1, which encodes Δ4-3-ketosteroid-5β-reductase (AKR1D1). This enzyme is a member of the aldoketo reductase superfamily, but possesses an altered catalytic tetrad, in which Glu120 replaces the conserved His residue. This predominant liver enzyme generates all 5β-dihydrosteroids in the C19–C27 steroid series. Mutations exist in the AKR1D1 gene, which result in loss of protein stability and are causative in bile-acid deficiency. PMID:24513054

An examination of the clinical benefits and cost-effectiveness of tocolytic replacement following recurrent preterm labor.

PubMed

Flick, Amy A; de la Torre, Lesley; Roca, Luis E; Istwan, Niki; Rhea, Debbie; Desch, Cheryl; González-Quintero, Victor Hugo

2010-01-01

We examined pregnancy outcomes in women receiving nifedipine tocolysis having recurrent preterm labor (RPTL). Singleton gestations enrolled for outpatient nursing surveillance and prescribed nifedipine tocolysis were identified (N = 4748). Women hospitalized for RPTL at <35 weeks then resuming outpatient surveillance were included (N = 1366). Pregnancy outcomes of women resuming nifedipine (N = 830) were compared with those having an alteration in treatment to continuous subcutaneous terbutaline (N = 536). Overall, 56.7% (2692/4748) experienced RPTL. Half (50.7%) were stabilized and resumed outpatient surveillance with nifedipine or continuous subcutaneous terbutaline. Infants from women resuming nifedipine versus those with alteration of treatment to terbutaline were more likely to deliver at <35 weeks (28.0% versus 13.8%), weigh <2500 g (32.9% versus 20.3%), and require a stay in the neonatal intensive care unit (34.0% versus 23.1%), all P < 0.001. Alteration of tocolytic treatment following RPTL resulted in a decreased incidence of preterm birth and low birth weight, resulting in less admission to the neonatal intensive care unit and fewer nursery days. Thieme Medical Publishers.

5β-Reduced steroids and human Δ(4)-3-ketosteroid 5β-reductase (AKR1D1).

PubMed

Chen, Mo; Penning, Trevor M

2014-05-01

5β-Reduced steroids are non-planar steroids that have a 90° bend in their structure to create an A/B cis-ring junction. This novel property is required for bile-acids to act as emulsifiers, but in addition 5β-reduced steroids have remarkable physiology and may act as potent tocolytic agents, endogenous cardiac glycosides, neurosteroids, and can act as ligands for orphan and membrane bound receptors. In humans there is only a single 5β-reductase gene AKR1D1, which encodes Δ(4)-3-ketosteroid-5β-reductase (AKR1D1). This enzyme is a member of the aldo-keto reductase superfamily, but possesses an altered catalytic tetrad, in which Glu120 replaces the conserved His residue. This predominant liver enzyme generates all 5β-dihydrosteroids in the C19-C27 steroid series. Mutations exist in the AKR1D1 gene, which result in loss of protein stability and are causative in bile-acid deficiency. Copyright © 2014 Elsevier Inc. All rights reserved.

Substrate specificity and inhibitor sensitivity of rabbit 20α-hydroxysteroid dehydrogenase.

PubMed

Endo, Satoshi; Arai, Yuki; Hara, Akira; Kitade, Yukio; Bunai, Yasuo; El-Kabbani, Ossama; Matsunaga, Toshiyuki

2013-01-01

In this study, we examined the substrate specificity and inhibitor sensitivity of rabbit 20α-hydroxysteroid dehydrogenase (AKR1C5), which plays a role in the termination of pregnancy by progesterone inactivation. AKR1C5 moderately reduced the 3-keto group of only 5α-dihydrosteroids with 17β- or 20α/β-hydroxy group among 3-ketosteroids. In contrast, the enzyme reversibly and efficiently catalyzed the reduction of various 17- and 20-ketosteroids, including estrogen precursors (dehydroepiandrosterone, estrone and 5α-androstan-3β-ol-17-one) and tocolytic 5β-pregnane-3,20-dione. In addition to the progesterone inactivation, the formation of estrogens and metabolism of the tocolytic steroid by AKR1C5 may be related to its role in rabbit parturition. AKR1C5 also reduced various non-steroidal carbonyl compounds, including isatin, an antagonist of the C-type natriuretic peptide receptor, and 4-oxo-2-nonenal, suggesting its roles in controlling the bioactive isatin and detoxification of cytotoxic aldehydes. AKR1C5 was potently and competitively inhibited by flavonoids such as kaempferol and quercetin, suggesting that its activity is affected by ingested flavonoids.

Interventions for helping to turn term breech babies to head first presentation when using external cephalic version.

PubMed

Cluver, Catherine; Hofmeyr, G Justus; Gyte, Gillian Ml; Sinclair, Marlene

2012-01-18

Breech presentation is associated with increased complications. Turning a breech baby to head first presentation using external cephalic version (ECV) attempts to reduce the chances of breech presentation at birth, and reduce the adverse effects of breech vaginal birth or caesarean section. Tocolytic drugs and other methods have been used in an attempt to facilitate ECV. To assess interventions such as tocolysis, fetal acoustic stimulation, regional analgesia, transabdominal amnioinfusion or systemic opioids on ECV for a breech baby at term. We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 September 2011) and the reference lists of identified studies. Randomised and quasi-randomised trials comparing the above interventions with no intervention or other methods to facilitate ECV at term. We assessed eligibility and trial quality. Two review authors independently assessed for inclusion all potential studies identified as a result of the search strategy and independently extracted the data using a designed data extraction form. We included 25 studies, providing data on 2548 women. We used the random-effects model for pooling data due to clinical heterogeneity in the included studies in the various comparisons. The overall quality of the evidence was reasonable, but a number of assessments had insufficient data to provide an answer with any degree of assurance.Tocolytic drugs, in particular betastimulants, were effective in increasing cephalic presentations in labour (average risk ratio (RR) 1.38, 95% confidence interval (CI) 1.03 to 1.85, eight studies, 993 women) and in reducing the number of caesarean sections (average RR 0.82, 95% CI 0.71 to 0.94, eight studies, 1177 women). No differences were identified in fetal bradycardias (average RR 0.95, 95% CI 0.48 to 1.89, three studies, 467 women) although the review is underpowered for assessing this outcome. We identified no difference in success, cephalic presentation in labour and caesarean sections between nulliparous and multiparous women. There were insufficient data comparing different groups of tocolytic drugs. Sensitivity analyses by study quality agreed with the overall findings.Regional analgesia in combination with a tocolytic was more effective than the tocolytic alone in terms of increasing successful versions (assessed by the rate of failed ECVs, average RR 0.67, 95% CI 0.51 to 0.89, six studies, 550 women) but there was no difference identified in cephalic presentation in labour (average RR 1.63, 95% CI 0.75 to 3.53, three studies, 279 women) nor in caesarean sections (average RR 0.74, 95% CI 0.40 to 1.37, three studies, 279 women) or fetal bradycardia (average RR 1.48, 95% CI 0.62 to 3.57, two studies, 210 women).There were insufficient data on the use of vibroacoustic stimulation, amnioinfusion or systemic opioids. Betastimulants, to facilitate ECV, increased cephalic presentation in labour and birth, and reduced the caesarean section rate in both nulliparous and multiparous women, but there were insufficient data on adverse effects. Calcium channel blockers and nitric acid donors had insufficient data to provide good evidence. At present we recommend betamimetics for facilitating ECV.There is scope for further research. The possible benefits of tocolysis to reduce the force required for successful version and the possible risks of maternal cardiovascular side effects, need to be addressed further. Further trials are needed to compare the effectiveness of routine versus selective use of tocolysis, the role of regional analgesia, fetal acoustic stimulation, amnioinfusion and the effect of intravenous or oral hydration prior to ECV.Although randomised trials of nitroglycerine are small, the results are sufficiently negative to discourage further trials.

Interventions for helping to turn term breech babies to head first presentation when using external cephalic version

PubMed Central

Cluver, Catherine; Hofmeyr, G Justus; Gyte, Gillian ML; Sinclair, Marlene

2014-01-01

Background Breech presentation is associated with increased complications. Turning a breech baby to head first presentation using external cephalic version (ECV) attempts to reduce the chances of breech presentation at birth, and reduce the adverse effects of breech vaginal birth or caesarean section. Tocolytic drugs and other methods have been used in an attempt to facilitate ECV. Objectives To assess interventions such as tocolysis, fetal acoustic stimulation, regional analgesia, transabdominal amnioinfusion or systemic opioids on ECV for a breech baby at term. Search methods We searched the Cochrane Pregnancy and Childbirth Group’s Trials Register (30 September 2011) and the reference lists of identified studies. Selection criteria Randomised and quasi-randomised trials comparing the above interventions with no intervention or other methods to facilitate ECV at term. Data collection and analysis We assessed eligibility and trial quality. Two review authors independently assessed for inclusion all potential studies identified as a result of the search strategy and independently extracted the data using a designed data extraction form. Main results We included 25 studies, providing data on 2548 women. We used the random-effects model for pooling data due to clinical heterogeneity in the included studies in the various comparisons. The overall quality of the evidence was reasonable, but a number of assessments had insufficient data to provide an answer with any degree of assurance. Tocolytic drugs, in particular betastimulants, were effective in increasing cephalic presentations in labour (average risk ratio (RR) 1.38, 95% confidence interval (CI) 1.03 to 1.85, eight studies, 993 women) and in reducing the number of caesarean sections (average RR 0.82, 95% CI 0.71 to 0.94, eight studies, 1177 women). No differences were identified in fetal bradycardias (average RR 0.95, 95% CI 0.48 to 1.89, three studies, 467 women) although the review is underpowered for assessing this outcome. We identified no difference in success, cephalic presentation in labour and caesarean sections between nulliparous and multiparous women. There were insufficient data comparing different groups of tocolytic drugs. Sensitivity analyses by study quality agreed with the overall findings. Regional analgesia in combination with a tocolytic was more effective than the tocolytic alone in terms of increasing successful versions (assessed by the rate of failed ECVs, average RR 0.67, 95% CI 0.51 to 0.89, six studies, 550 women) but there was no difference identified in cephalic presentation in labour (average RR 1.63, 95% CI 0.75 to 3.53, three studies, 279 women) nor in caesarean sections (average RR 0.74, 95% CI 0.40 to 1.37, three studies, 279 women) or fetal bradycardia (average RR 1.48, 95% CI 0.62 to 3.57, two studies, 210 women). There were insufficient data on the use of vibroacoustic stimulation, amnioinfusion or systemic opioids. Authors’ conclusions Betastimulants, to facilitate ECV, increased cephalic presentation in labour and birth, and reduced the caesarean section rate in both nulliparous and multiparous women, but there were insufficient data on adverse effects. Calcium channel blockers and nitric acid donors had insufficient data to provide good evidence. At present we recommend betamimetics for facilitating ECV. There is scope for further research. The possible benefits of tocolysis to reduce the force required for successful version and the possible risks of maternal cardiovascular side effects, need to be addressed further. Further trials are needed to compare the effectiveness of routine versus selective use of tocolysis, the role of regional analgesia, fetal acoustic stimulation, amnioinfusion and the effect of intravenous or oral hydration prior to ECV. Although randomised trials of nitroglycerine are small, the results are sufficiently negative to discourage further trials. PMID:22258940

Techniques for assisting difficult delivery at caesarean section.

PubMed

Waterfall, Heather; Grivell, Rosalie M; Dodd, Jodie M

2016-01-31

Caesarean section involves making an incision in the woman's abdomen and cutting through the uterine muscle. The baby is then delivered through that incision. Difficult caesarean birth may result in injury for the infant or complications for the mother. Methods to assist with delivery include vacuum or forceps extraction or manual delivery utilising fundal pressure. Medication that relaxes the uterus (tocolytic medication) may facilitate the birth of the baby at caesarean section. Delivery of the impacted head after prolonged obstructed labour can be associated with significant maternal and neonatal complication; to facilitate delivery of the head the surgeon may utilise either reverse breech extraction or head pushing. To compare the use of tocolysis (routine or selective use) with no use of tocolysis or placebo and to compare different extraction methods at the time of caesarean section for outcomes of infant birth trauma, maternal complications (particularly postpartum haemorrhage requiring blood transfusion), and long-term measures of infant and childhood morbidity. We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 September 2015) and reference lists of retrieved studies. All published, unpublished, and ongoing randomised controlled trials comparing the use of tocolytic agents (routine or selective) at caesarean section versus no use of tocolytic or placebo at caesarean section to facilitate the birth of the baby. Use of instrument versus manual delivery to facilitate birth of the baby. Reverse breech extraction versus head pushing to facilitate delivery of the deeply impacted fetal head. Two review authors independently assessed trials for inclusion and risk of bias, extracted data and checked them for accuracy. Seven randomised controlled trials, involving 582 women undergoing caesarean section were included in this review. The risk of bias of included trials was variable, with some trials not adequately describing allocation or randomisation.Three comparisons were included. 1. Tocolysis versus no tocolysisA single randomised trial involving 97 women was identified and included in the review. Birth trauma was not reported. There were no cases of any maternal side-effect reported in either the nitroglycerin or the placebo group. No other maternal and infant health outcomes were reported. 2. Reverse breech extraction versus head push for the deeply impacted head at full dilation at caesarean section Four randomised trials involving 357 women were identified and included in the review. The primary outcome of birth trauma was reported by three trials and there was no difference between reverse breech extraction and head push for this rare outcome (three studies, 239 women, risk ratio (RR) 1.55, 95% confidence interval (CI) 0.42 to 5.73). Secondary outcomes including endometritis rate (three studies, 285 women, average RR 0.52, 95% CI 0.26 to 1.05, Tau I² = 0.22, I² = 56%), extension of uterine incision (four studies, 357 women, average RR 0.23, 95% CI 0.13 to 0.40), mean blood loss (three studies, 298 women, mean difference (MD) -294.92, 95% CI -493.25 to -96.59; I² = 98%) and neonatal intensive care unit (NICU)/special care nursery (SCN) admission (two studies, 226 babies, average RR 0.53, 95% CI 0.23 to 1.22, Tau I² = 0.27, I² = 74%) were decreased with reverse breech extraction. No differences were observed between groups for many of the other secondary outcomes reported (blood loss > 500 mL; blood transfusion; wound infection; mean hospital stay; average Apgar score).There was significant heterogeneity between the trials for the outcomes mean blood loss, operative time and mean hospital stay, making comparison difficult. However the operation duration was significantly shorter for reverse breech extraction, which may correspond with ease of delivery and therefore, the amount of tissue trauma and therefore, significantly less blood loss. Given the heterogeneity, we cannot define the amount of difference in blood loss, operative time or hospital stay however. 3. Instrument (vacuum or forceps) versus manual extraction at elective caesarean section Two randomised trials involving 128 women were identified and included in the review. Only one trial reported maternal and infant health outcomes as prespecified in this review. This trial reported birth trauma as an outcome but there were no instances of birth trauma in either comparison group. There were no differences found in mean fall in haemoglobin (Hb) between groups (one study, 44 women, MD 0.03, 95% CI -0.53 to 0.59), or in uterine incision extension (one study, 44 women, RR 0.70, 95% CI 0.13 to 3.73). There is currently insufficient information available from randomised trials to support or refute the routine or selective use of tocolytic agents or instrument to facilitate infant birth at the time of difficult caesarean section. There is limited evidence that reverse breech extraction may improve maternal and fetal outcomes, though there was no difference in primary outcome of infant birth trauma. Further randomised controlled trials are needed to answer these questions.

Nifedipine versus fenoterol in the management of preterm labor: a randomized, multicenter clinical study.

PubMed

Valdés, E; Salinas, H; Toledo, V; Lattes, K; Cuellar, E; Perucca, E; Diaz, R; Montecinos, F; Reyes, A

2012-01-01

To compare the efficacy of nifedipine and fenoterol in the management of threatened preterm labor (TPL). A randomized and multicenter study assessing the tocolytic effect of nifedipine versus fenoterol in patients admitted to the participating maternity units with a diagnosis of TPL and a cost-savings study for economic assessment. For a power of 80% and an α error equal to 0.05, 132 consecutive patients were recruited during the study period; 66 patients were assigned to each group. A χ(2) analysis and a mean differences test were performed according to variable types and survival curves per intention-to-treat. Demographics were similar in both groups. The latency period was similar in both groups (26.7 vs. 25.6; p = 0.3). There were no differences in the results obtained. Nifedipine failed more frequently to obtain tocolysis when used as a first-line agent (80 vs. 90%, p = 0.0001). The group treated with fenoterol showed more drug adverse events (57.8 vs. 19.0%, p = 0.0001). The economic assessment did not evidence a significant difference in terms of cost savings between groups treated with either drug. The present study failed to demonstrate either clinical or economic superiority of any of the two drugs used in TPL management. The highest failure percentage of nifedipine when used as a first-line agent should encourage further research. Copyright © 2012 S. Karger AG, Basel.

Have we achieved progress in tocolytic treatment?--results of a retrospective cohort study in a tertiary university hospital.

PubMed

Tomczyk, Katarzyna; Rzymski, Paweł; Wilczak, Maciej

2015-07-01

Beta-agonists play an important role in tocolytic treatment. In light of recent changes in the Polish medical care system, we decided to assess the effectiveness of oral continuous treatment (in 2012) and compare it with a 3-day intravenous administration of fenoterol (in 2013). The aim of our study was to contrast cost and effectiveness of fenoterol therapy in pregnant women at risk of preterm labor during two consecutive years: 2012 - when fenoterol had been widely used (group A), and 2013 when its extensive use had been withdrawn (group B). Retrospective cohort study of 129 pregnant women: 76 treated with intravenous fenoterol, followed by continuous oral administration (November 2012; group A), and 53 treated with intravenous fenoterol only for 48-72 hours (November 2013; group B). Perinatal outcomes (based on the Apgar score and neonatal weight) were comparable in both groups. Continuous oral application of fenoterol resulted in earlier gestational age at delivery and lower cost of hospitalization among women from group A as compared to group B. Regardless, the difference was not statistically significant (37 hbd vs. 35 hbd, p = 0.626; 4334,700PLN vs. 5232,470PLN, p = 0.533). A 3-day intravenous application of fenoterol is as effective as oral continuous therapy and is characterized by reduced risk of negative side effects.

Increased Systemic Exposure and Stronger Cardiovascular and Metabolic Adverse Reactions to Fenoterol in Individuals with Heritable OCT1 Deficiency.

PubMed

Tzvetkov, Mladen V; Matthaei, Johannes; Pojar, Sherin; Faltraco, Frank; Vogler, Sabrina; Prukop, Thomas; Seitz, Tina; Brockmöller, Jürgen

2018-05-01

Fenoterol is a widely used anti-asthmatic and tocolytic agent, but high plasma concentrations of fenoterol may lead to severe and even fatal adverse reactions. We studied whether heritable deficiency of the liver organic cation transporter 1 (OCT1), a trait observed in 3% of Europeans and white Americans, affects fenoterol plasma concentrations and toxicity. OCT1 transported fenoterol with high affinity, and OCT1 inhibition in human hepatocytes reduced fenoterol uptake threefold. After administration of 180 µg of fenoterol to 39 healthy individuals, the OCT1-deficient individuals (zero active OCT1 alleles; n = 5) showed 1.9-fold greater systemic fenoterol exposure (P = 4.0 × 10 -5 ) and 1.7-fold lower volume of distribution (P = 8.0 × 10 -5 ). Correspondingly, the OCT1-deficient individuals had a 1.5-fold stronger increase in heart rate (P = 0.002), a 3.4-fold greater increase in blood glucose (P = 3.0 × 10 -5 ), and significantly lower serum potassium levels. In conclusion, heritable OCT1 deficiency significantly increases plasma concentrations of fenoterol and may be an important factor underlying the excess mortality associated with fenoterol. © 2017 American Society for Clinical Pharmacology and Therapeutics.

Interventions for helping to turn term breech babies to head first presentation when using external cephalic version.

PubMed

Cluver, Catherine; Gyte, Gillian M L; Sinclair, Marlene; Dowswell, Therese; Hofmeyr, G Justus

2015-02-09

Breech presentation is associated with increased complications. Turning a breech baby to head first presentation using external cephalic version (ECV) attempts to reduce the chances of breech presentation at birth so as to avoid the adverse effects of breech vaginal birth or caesarean section. Interventions such as tocolytic drugs and other methods have been used in an attempt to facilitate ECV. To assess, from the best evidence available, the effects of interventions such as tocolysis, acoustic stimulation for midline spine position, regional analgesia (epidural or spinal), transabdominal amnioinfusion, systemic opioids and hypnosis, or the use of abdominal lubricants, on ECV at term for successful version, presentation at birth, method of birth and perinatal and maternal morbidity and mortality. We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (30 September 2014) and the reference lists of identified studies. Randomised and quasi-randomised trials comparing the above interventions with no intervention or other methods to facilitate ECV at term. We assessed eligibility and trial quality. Two review authors independently assessed for inclusion all potential studies identified as a result of the search strategy and independently extracted the data using a specially designed data extraction form. We included 28 studies, providing data on 2786 women. We used the random-effects model for pooling data because of clinical heterogeneity between studies. A number of trial reports gave insufficient information to allow clear assessment of risk of bias. We used GradePro software to carry out formal assessments of quality of the evidence for beta stimulants versus placebo and regional analgesia with tocolysis versus tocolysis alone.Tocolytic parenteral beta stimulants were effective in increasing cephalic presentations in labour (average risk ratio (RR) 1.68, 95% confidence interval (CI) 1.14 to 2.48, five studies, 459 women, low-quality evidence) and in reducing the number of caesarean sections (average RR 0.77, 95% CI 0.67 to 0.88, six studies, 742 women, moderate-quality evidence). Failure to achieve a cephalic vaginal birth was less likely for women receiving a parenteral beta stimulant (average RR 0.75, 95% CI 0.60 to 0.92, four studies, 399 women, moderate-quality evidence). No clear differences in fetal bradycardias were identified, although this was reported for only one study, which was underpowered for assessing this outcome. Failed external cephalic version was reported in nine studies (900 women), and women receiving parenteral beta stimulants were less likely to have failure compared with controls (average RR 0.70, 95% CI 0.60 to 0.82, moderate-quality evidence). Perinatal mortality and serious morbidity were not reported. Sensitivity analysis by study quality was consistent with overall findings.For other classes of tocolytic drugs (calcium channel blockers and nitric oxide donors), evidence was insufficient to permit conclusions; outcomes were reported for only one or two studies, which were underpowered to demonstrate differences between treatment and control groups. Little evidence was found regarding adverse effects, although nitric oxide donors were associated with increased risk of headache. Data comparing different tocolytic drugs were insufficient.Regional analgesia in combination with a tocolytic was more effective than the tocolytic alone for increasing successful versions (assessed by the rate of failed ECVs; average RR 0.61, 95% CI 0.43 to 0.86, five studies, 409 women, moderate-quality evidence), and no difference was identified in cephalic presentation in labour (average RR 1.63, 95% CI 0.75 to 3.53, three studies, 279 women, very low-quality evidence), caesarean sections (average RR 0.74, 95% CI 0.40 to 1.37, three studies, 279 women, very low-quality evidence) nor fetal bradycardia (average RR 1.48, 95% CI 0.62 to 3.57, two studies, 210 women, low-quality evidence), although studies were underpowered for assessing these outcomes. Studies did not report on failure to achieve a cephalic vaginal birth (breech vaginal deliveries plus caesarean sections) nor on perinatal mortality or serious infant morbidity.Data were insufficient on the use of regional analgesia without tocolysis, vibroacoustic stimulation, amnioinfusion, systemic opioids and hypnosis, and on the use of talcum powder or gel to assist external cephalic version, to permit conclusions about their effectiveness and safety. Parenteral beta stimulants were effective in facilitating successful ECV, increasing cephalic presentation in labour and reducing the caesarean section rate, but data on adverse effects were insufficient. Data on calcium channel blockers and nitric acid donors were insufficient to provide good evidence.The scope for further research is clear. Possible benefits of tocolysis in reducing the force required for successful version and possible risks of side effects need to be addressed further. Further trials are needed to compare the effectiveness of routine versus selective use of tocolysis and the role of regional analgesia, fetal acoustic stimulation, amnioinfusion and abdominal lubricants, and the effects of hypnosis, in facilitating ECV. Although randomised trials of nitric oxide donors are small, the results are sufficiently negative to discourage further trials. Intervention fidelity for ECV can be enhanced by standardisation of the techniques and processes used for clinical manipulation of the fetus in the abdominal cavity and ought to be the subject of further research.

[Atosiban treatment for preterm labor--financial considerations and savings by implementing clinical guidelines].

PubMed

Hadar, Eran; Mansur, Nariman; Ambar, Irit; Hod, Moshe

2011-06-01

Preterm delivery is a significant cause of neonatal morbidity and mortality. Pregnant women, with symptoms and signs consistent with preterm labor, can be treated with various tocolytic drugs. Atosiban is one of many drugs indicated to arrest imminent preterm labor. Various studies show that the efficacy of atosiban is similar to other tocolytic drugs. The main advantage of atosiban is a relativeLy low incidence of adverse maternal reactions. Its considerable shortcoming is the financial cost, compared to other available drugs. In view of its cost, we have decided to implement a strict protocol to direct the use of atosiban, with the intent to reduce costs, without hampering quality of care. The protocol was implemented from July 2009, and it outlines the medical and procedural terms to use atosiban. We compared similar time periods before and after implementation of the protocol. The outcomes compared included: treatment success, rates of preterm deliveries and financial costs. Within the timeframe that the protocol was implemented, we have been able to demonstrate a 40% reduction in atosiban related costs, compared to a parallel period, when the clinical guidelines were not implemented. This translates into savings of about NIS 40,000 (New Israeli Shekel) (approximately $10,000). This was achieved without an increase in the rate of preterm deliveries. Implementing and enforcing a simple protocol of supervision on the use of atosiban enables a considerable reduction of financial costs related to atosiban, without hampering medical care.

Preterm labor in the quadriplegic parturient.

PubMed

Catanzarite, V A; Ferguson, J E; Weinstein, C; Belton, S R

1986-04-01

The occurrence of preterm labor is not uncommon in the pregnant quadriplegic. Early diagnosis is hampered by the inability of most quadriplegics to sense uterine contractions in the usual way. A patient we recently treated for preterm labor learned to recognize contractions by the associated symptoms of autonomic hyper-reflexia: flushing, headache, and piloerection. Tocolytic therapy was successful and a favorable neonatal outcome occurred. Increased awareness by the physician and the pregnant quadriplegic patient is encouraged so that symptoms of autonomic hyper-reflexia may be recognized as potentially indicative of uterine contractions.

[Nitroglycerin patch for tocolysis--a prospective randomized comparison with fenoterol by infusion].

PubMed

Schleussner, E; Richter, S; Gross, W; Kähler, C; Möller, A; Möller, U; Seewald, H J

2001-01-01

To evaluate tocolytic efficacy of transdermal glyceryl trinitrate (GTN) in comparison to fenoterol per infusionem in a prospective randomized multicenter study. 50 pregnant women between 27 and 35 weeks of gestation with preterm labour were treated with either GTN patches (0.4-0.8 mg/h) or fenoterol per infusionem (60-120 micrograms/h) up to stop of contractions or 35 weeks in maximum. The primary outcomes were the prolongation of gestation by 48 h, 7 days or up to 37 weeks of gestation as well as the neonatal outcome. The progression of cervical ripening and maternal side effects during tocolysis were assessed as secondary outcome criteria. There was no difference in successful tocolysis for 48 h and 7 days in both groups, whereas significantly more women passed 37 weeks after GTN therapy. So mean duration of pregnancy, birth weight and height were greater, whereas transfer into neonatal care unit was significantly rare after GTN. There were no differences in neonatal outcome and progression of cervical ripening during tocolysis. Maternal side effects during GTN were fewer and weaker compared with fenoterol. Circa 70% of GTN treated women had a headache temporary, whereas more than 90% of the patients with fenoterol suffered from tachycardia and tremor. Tocolytic efficacy of transdermal GTN was at least equivalent to the established beta-mimetic therapy with fenoterol. Because of the lower preterm delivery rate transfer into neonatal care for control was significantly rarer after GTN with equally good neonatal outcome in both groups. Beside the headache transdermal GTN therapy had lower maternal side effects in comparison to fenoterol.

Oxytocin Receptor Antagonist (Atosiban) in the Threat of Preterm Birth: Does It Have Any Effect on Breastfeeding in the Term Newborn?

PubMed

López Gómez, Lucía; Marín Gabriel, Miguel A; Encinas, Begoña; de la Cruz Troca, Juan J; Rodríguez Marrodán, Belén

2018-03-01

Oxytocin is a hormone involved in the mechanism of breastfeeding, uterine contractions, and social relationships. Atosiban (competitive oxytocin antagonist) is one of the most commonly used tocolytics for the threat of preterm labor in Europe. The aim of this study is to determinate if the administration of atosiban has any influence in the type of feeding in the term newborn at discharge. The secondary objective is to verify its effectiveness for the prevention of preterm delivery and in the possibility of applying treatment to complete lung maturation. Retrospective cohort study carried out in a tertiary University Hospital distinguished by WHO-UNICEF as a Baby-Friendly Hospital Initiative. The analysis included 264 women exposed to atosiban during a period of 4 years. One hundred met inclusion criteria. Unexposed infants born right after and before the exposed ones were selected as the not exposed subgroup (n = 200). Among women treated with atosiban, 82% maintained exclusively breastfed (EBF), 8% had mixed breastfeeding, and 10% had formula feeding at discharge. In the nonexposed group, 82% maintained EBF, 9.5% had mixed breastfeeding, and 8.5% had formula feeding at discharge (p = 0.84). 97.5% of pregnant women treated with atosiban received corticosteroid for lung maturation, and 49.5% completed gestation with term newborns. There were no significant differences in the type of feeding at discharge between the atosiban group and the nonexposed group. In most cases, the administration of tocolytic therapy allowed to complete lung maturation.

Drug delivery to the human and mouse uterus using immunoliposomes targeted to the oxytocin receptor.

PubMed

Paul, Jonathan W; Hua, Susan; Ilicic, Marina; Tolosa, Jorge M; Butler, Trent; Robertson, Sarah; Smith, Roger

2017-03-01

The ability to provide safe and effective pharmacotherapy during obstetric complications, such as preterm labor or postpartum hemorrhage, is hampered by the systemic toxicity of therapeutic agents leading to adverse side effects in the mother and fetus. Development of novel strategies to target tocolytic and uterotonic agents specifically to uterine myocytes would improve therapeutic efficacy while minimizing the risk of side effects. Ligand-targeted liposomes have emerged as a reliable and versatile platform for targeted drug delivery to specific cell types, tissues or organs. Our objective was to develop a targeted drug delivery system for the uterus utilizing an immunoliposome platform targeting the oxytocin receptor. We conjugated liposomes to an antibody that recognizes an extracellular domain of the oxytocin receptor. We then examined the ability of oxytocin receptor-targeted liposomes to deliver contraction-blocking (nifedipine, salbutamol and rolipram) or contraction-enhancing (dofetilide) agents to strips of spontaneously contracting myometrial tissue in vitro (human and mouse). We evaluated the ability of oxytocin receptor-targeted liposomes to localize to uterine tissue in vivo, and assessed if targeted liposomes loaded with indomethacin were capable of preventing lipopolysaccharide-induced preterm birth in mice. Oxytocin receptor-targeted liposomes loaded with nifedipine, salbutamol or rolipram consistently abolished human myometrial contractions in vitro, while oxytocin receptor-targeted liposomes loaded with dofetilide increased contraction duration. Nontargeted control liposomes loaded with these agents had no effect. Similar results were observed in mouse uterine strips. Following in vivo administration to pregnant mice, oxytocin receptor-targeted liposomes localized specifically to the uterine horns and mammary tissue. Targeting increased localization to the uterus 7-fold. Localization was not detected in the maternal brain or fetus. Targeted and nontargeted liposomes also localized to the liver. Oxytocin receptor-targeted liposomes loaded with indomethacin were effective in reducing rates of preterm birth in mice, whereas nontargeted liposomes loaded with indomethacin had no effect. Our results demonstrate that oxytocin receptor-targeted liposomes can be used to either inhibit or enhance human uterine contractions in vitro. In vivo, the liposomes localized to the uterine tissue of pregnant mice and were effective in delivering agents for the prevention of inflammation-induced preterm labor. The potential clinical advantage of targeted liposomal drug delivery to the myometrium is reduced dose and reduced toxicity to both mother and fetus. Copyright © 2016. Published by Elsevier Inc.

Comparison of the relaxation effect in vitro of nitroglycerin vs. fenoterol on human myometrial strips.

PubMed

David, M; Hamann, C; Chen, F C; Bruch, L; Lichtenegger, W

2000-01-01

Substance dose-related comparison of relaxation effect of nitroglycerin (GTN) and the beta 2-mimetic substance fenoterol in human myometrial tissue. Test criterion is the isometric force development of isolated human myometrial strips. These muscle strips were removed from the lower uterine segment at cesarean section. Fenoterol in concentrations of 3 x 10(-8)-10(-5) mol/l or GTN in concentrations of 1.7 x 10(-8)-5.8 x 10(-4) mol/l were applied to the 2 x 2 x 10-mm strips, which were fixed and maintained in tissue baths. The curves were plotted on line. The integral or the "area under the curve" (AUC) served as the parameter for muscle strip activity. A total of 100 strips from 20 patients were used. GTN demonstrated a significant relaxation effect in the in vitro model on human myometrial strips from pregnant women already treated with oxytocin. The effect was able to be enhanced to a point where oxytocin-induced contractions were completely absent. A relatively clear connection was demonstrated between dose and effect whereby increased muscle relaxation resulted at increased concentrations. Compared to GTN application, muscle strip relaxation was less pronounced under fenoterol; a complete inhibition of myometrial activity was not achieved under fenoterol. With respect to relaxation of the myometrial tissue samples the NO donor GTN is at least as potent as the standard tocolytic agent fenoterol in the in vitro model.

[Management of pre-term labor: use of nifedipine in Conakry, Guinea].

PubMed

Sy, T; Diallo, F B; Diallo, Y; Camara, M K; Diallo, A; Cissoko, M; Lontsi, G R; Diallo, M S

2010-04-01

This purpose of this prospective and descriptive study was to evaluate the utility of a calcium-channel inhibitor, i.e. nifedipine, for management of preterm labor in our work setting in terms of safety and cost-effectiveness in comparison with betamimetics classically used for this indication. Study was carried out over a six-month period in the department of Gynecology-Obstetrics Department of Ignace Deen National Hospital in Conakry, Guinea. Pregnant women meeting the following criteria were included: 28 to 33 weeks of amenorrhea, six days of hospitalization either for preterm labor or for another diagnosis that was associated with the occurrence of preterm labor during hospitalization, and absence of contraindications for tocolysis using nifedipine. A total of 42 women were included. Pregnancy was extended for more than 48 hours after the first dose of nifedipine in 86.8% of cases. Administration of nifedipine failed in 5 cases including one case in which it was necessary to change the tocolytic and 4 cases in which delivery occurred less than 48 hours after the first dose of nifedipine. In 68% of cases, 90 mg of nifedipine were sufficient to stop uterine contractions within 48 hours. In 39.5% of cases, no side effects were observed. Adverse effects in the other cases were dizziness (39.5%) and headache (18.4%). The mean term of delivery was 36 weeks +/- 5 days of amenorrhea with a mean extension of 6.2 weeks. Apgar score was low in 30.5% of the newborns and normal in 69.5%. One newborn (2.8%) died. The results of this study indicate that nifedipine is an effective, economical and safe drug for tocolysis and that it can be used as an alternative to betamimetis in countries with limited resources. An information campaign is needed to promote use of nifedipine as a tocolytic in obstetrical facilities of our country.

Computational modeling of inhibition of voltage-gated Ca channels: identification of different effects on uterine and cardiac action potentials.

PubMed

Tong, Wing-Chiu; Ghouri, Iffath; Taggart, Michael J

2014-01-01

The uterus and heart share the important physiological feature whereby contractile activation of the muscle tissue is regulated by the generation of periodic, spontaneous electrical action potentials (APs). Preterm birth arising from premature uterine contractions is a major complication of pregnancy and there remains a need to pursue avenues of research that facilitate the use of drugs, tocolytics, to limit these inappropriate contractions without deleterious actions on cardiac electrical excitation. A novel approach is to make use of mathematical models of uterine and cardiac APs, which incorporate many ionic currents contributing to the AP forms, and test the cell-specific responses to interventions. We have used three such models-of uterine smooth muscle cells (USMC), cardiac sinoatrial node cells (SAN), and ventricular cells-to investigate the relative effects of reducing two important voltage-gated Ca currents-the L-type (ICaL) and T-type (ICaT) Ca currents. Reduction of ICaL (10%) alone, or ICaT (40%) alone, blunted USMC APs with little effect on ventricular APs and only mild effects on SAN activity. Larger reductions in either current further attenuated the USMC APs but with also greater effects on SAN APs. Encouragingly, a combination of ICaL and ICaT reduction did blunt USMC APs as intended with little detriment to APs of either cardiac cell type. Subsequent overlapping maps of ICaL and ICaT inhibition profiles from each model revealed a range of combined reductions of ICaL and ICaT over which an appreciable diminution of USMC APs could be achieved with no deleterious action on cardiac SAN or ventricular APs. This novel approach illustrates the potential for computational biology to inform us of possible uterine and cardiac cell-specific mechanisms. Incorporating such computational approaches in future studies directed at designing new, or repurposing existing, tocolytics will be beneficial for establishing a desired uterine specificity of action.

Computational modeling of inhibition of voltage-gated Ca channels: identification of different effects on uterine and cardiac action potentials

PubMed Central

Tong, Wing-Chiu; Ghouri, Iffath; Taggart, Michael J.

2014-01-01

The uterus and heart share the important physiological feature whereby contractile activation of the muscle tissue is regulated by the generation of periodic, spontaneous electrical action potentials (APs). Preterm birth arising from premature uterine contractions is a major complication of pregnancy and there remains a need to pursue avenues of research that facilitate the use of drugs, tocolytics, to limit these inappropriate contractions without deleterious actions on cardiac electrical excitation. A novel approach is to make use of mathematical models of uterine and cardiac APs, which incorporate many ionic currents contributing to the AP forms, and test the cell-specific responses to interventions. We have used three such models—of uterine smooth muscle cells (USMC), cardiac sinoatrial node cells (SAN), and ventricular cells—to investigate the relative effects of reducing two important voltage-gated Ca currents—the L-type (ICaL) and T-type (ICaT) Ca currents. Reduction of ICaL (10%) alone, or ICaT (40%) alone, blunted USMC APs with little effect on ventricular APs and only mild effects on SAN activity. Larger reductions in either current further attenuated the USMC APs but with also greater effects on SAN APs. Encouragingly, a combination of ICaL and ICaT reduction did blunt USMC APs as intended with little detriment to APs of either cardiac cell type. Subsequent overlapping maps of ICaL and ICaT inhibition profiles from each model revealed a range of combined reductions of ICaL and ICaT over which an appreciable diminution of USMC APs could be achieved with no deleterious action on cardiac SAN or ventricular APs. This novel approach illustrates the potential for computational biology to inform us of possible uterine and cardiac cell-specific mechanisms. Incorporating such computational approaches in future studies directed at designing new, or repurposing existing, tocolytics will be beneficial for establishing a desired uterine specificity of action. PMID:25360118

Cost-effectiveness of ritodrine and fenoterol for treatment of preterm labor in a low-middle-income country: a case study.

PubMed

Jakovljevic, Mihajlo; Varjacic, Mirjana; Jankovic, Slobodan M

2008-01-01

In countries with high income, tocolytic therapy with beta-mimetic agents is a cost-effective strategy compared to placebo. In our study, the cost-effectiveness of two beta-mimetic agents, ritodrine and fenoterol, used in the management of preterm labor was compared in the setting of a low-middle-income transitional country, Serbia & Montenegro. This case study was conducted at the Gynecology-Obstetrics Clinic, Clinical Center "Kragujevac," in Kragujevac, Serbia & Montenegro, between October 2004 and January 2006. In total, 235 pregnant patients with threatened preterm labor were enrolled, but 35 were lost to follow-up. Of the remaining 200 patients, 85 were given ritodrine, and 115 fenoterol. The perspective of Republic Institute for Health Insurance in Serbia was taken into account. Only direct costs were calculated; primary outcomes of the study were length of pregnancy (in weeks), time passed from the onset of uterine contractions to delivery (in weeks), and score on modified Flanagan's quality-of-life scale for chronic diseases, measured after discharge from hospital. Prolongation of pregnancy was significantly longer in the fenoterol group (12.7 +/- 8.4 weeks) than in the ritodrine group (11.6 +/- 7.1 weeks). The mean duration of hospitalization was shorter in the fenoterol group (11.9 +/- 8.8 days) than in the ritodrine group (14.9 +/- 11.3 days). The treatment with fenoterol was less costly and more cost-effective than the treatment with ritodrine, but the difference in cost-effectiveness was not statistically significant. The cost of treatment per gained week of pregnancy prolongation was 3345.51 +/- 7668.04 CSD in the fenoterol group, and 4181.96 +/- 12,069.83 CSD in the ritodrine group. The observed differences in treatment costs and duration of hospitalization per patient did not translate into significant differences in cost-effectiveness ratios, because of low costs of hospitalization and human labor in Serbian health system. Nevertheless, fenoterol treatment still has a tendency to be more cost-effective, and its lower acquisition cost is an advantage to this treatment option.

[The Application of Bryophyllum pinnatum Preparations in Obstetrics and Gynaecology – a Multicenter, Prospective Observational Study].

PubMed

Fürer, Karin; Simões-Wüst, Ana Paula; Winkler, Alice; Amsler, Nadine; Schnelle, Martin; von Mandach, Ursula

2015-01-01

Bryophyllum pinnatum has been introduced in anthroposophic medicine in Europe and is nowadays also widely used in conventional medicine. The aim of this study was to assess the prescriptions in the field of gynaecology and obstetrics in Switzerland and to document potential effects and possible adverse events of B. pinnatum. Private practices and clinics for obstetrics and gynaecology were asked to document each prescription of B. pinnatum for their female patients during 31 months with an online questionnaire. At the University Hospital Zurich, at the Cantonal Hospital Winterthur as well as at 2 private practices, a total of 174 women and 208 prescriptions of B. pinnatum were recorded (several prescriptions per patient were possible). Most of the patients were pregnant (87%). B. pinnatum was prescribed as a tocolytic agent to 83% of all patients and to 95% of all pregnant patients and showed a good or a very good effectiveness. Further, 14% of the patients received B. pinnatum for sedation against their restlessness during the day and 5% for sedation against sleep problems. A decrease of the restlessness was achieved for these 2 indications. 13% of the patients suffered from a hyperactive bladder and in two-thirds of them the effectiveness of the treatment with B. pinnatum was classified as very good. In 92% of the cases, Bryophyllum 50% chewable tablets were prescribed. In conventional gynaecology and obstetrics, B. pinnatum is predominantly prescribed for pregnant women in case of prematurel abour, against restlessness and for hyperactive bladder. B. pinnatum showed a good effectiveness with a high benefit in the treatment of hyperactivity-associated health problems. © 2015 S. Karger GmbH, Freiburg.

Successful magnesium sulfate tocolysis: is "weaning" the drug necessary?

PubMed

Lewis, D F; Bergstedt, S; Edwards, M S; Burlison, S; Gallaspy, J W; Brooks, G G; Adair, C D

1997-10-01

Magnesium sulfate is the most commonly used tocolytic agent for preterm labor. A common clinical practice is to slowly discontinue the drug (wean) after successful tocolysis. Our objective was to determine the necessity of this practice. A prospective, randomized clinical trial was performed from June 1993 to July 1996. After successful magnesium sulfate tocolysis, patients with preterm labor were randomized to two groups: stopping the drug abruptly (no weaning) or gradually weaning the drug (approximately 1 gm every 4 hours). Preterm labor was defined as documented cervical change with regular uterine contractions or regular uterine contractions with a cervix of 2 cm and 75% effacement. The primary outcome variable was the necessity to reinstitute magnesium sulfate therapy within 24 hours of discontinuation of successful tocolysis. One hundred forty-one patients completed the study. No patient in the no-wean group required retocolysis within 24 hours of magnesium discontinuation. However, eight patients in the wean group required retocolysis within 24 hours of magnesium discontinuation (p = 0.01). Significantly more patients in the wean group had retocolysis during pregnancy (3 vs 12, p = 0.03). Patients in the wean group were also in the labor and delivery unit longer and, as would be anticipated, received magnesium sulfate significantly longer. No differences in the neonatal outcomes were noted between the two groups. Seventy-seven percent of the patients in the study were delivered prematurely. This study demonstrated an increased need for retocolysis in the group weaned from magnesium sulfate. We also found that patients in the wean group had an increased labor and delivery time and a longer administration time of magnesium sulfate. Thus weaning magnesium sulfate increases health care cost. The practice of weaning magnesium sulfate does not appear beneficial.

Introducing external cephalic version in a Malaysian setting.

PubMed

Yong, Stephen P Y

2007-02-01

To assess the outcome of external cephalic version for routine management of malpresenting foetuses at term. Prospective observational study. Tertiary teaching hospital, Malaysia. From September 2003 to June 2004, a study involving 41 pregnant women with malpresentation at term was undertaken. An external cephalic version protocol was implemented. Data were collected for identifying characteristics associated with success or failure of external cephalic version. Maternal and foetal outcome measures including success rate of external cephalic version, maternal and foetal complications, and characteristics associated with success or failure; engagement of presenting part, placental location, direction of version, attempts at version, use of intravenous tocolytic agent, eventual mode of delivery, Apgar scores, birth weights, and maternal satisfaction with the procedure. Data were available for 38 women. External cephalic version was successful in 63% of patients; the majority (75%) of whom achieved a vaginal delivery. Multiparity (odds ratio=34.0; 95% confidence interval, 0.67-1730) and high amniotic fluid index (4.9; 1.3-18.2) were associated with successful external cephalic version. Engagement of presenting part (odds ratio=0.0001; 95% confidence interval, 0.00001-0.001) and a need to resort to backward somersault (0.02; 0.00001-0.916) were associated with poor success rates. Emergency caesarean section rate for foetal distress directly resulting from external cephalic version was 8%, but there was no perinatal or maternal adverse outcome. The majority (74%) of women were satisfied with external cephalic version. External cephalic version has acceptable success rates. Multiparity, liquor volume, engagement of presenting part, and the need for backward somersault were strong predictors of outcome. External cephalic version is relatively safe, simple to learn and perform, and associated with maternal satisfaction. Modern obstetric units should routinely offer the procedure.

Resveratrol protects from lipopolysaccharide-induced inflammation in the uterus and prevents experimental preterm birth.

PubMed

Bariani, María Victoria; Correa, Fernando; Leishman, Emma; Domínguez Rubio, Ana Paula; Arias, Andreína; Stern, Aníbal; Bradshaw, Heather B; Franchi, Ana María

2017-08-01

Is resveratrol able to prevent the lipopolysaccharide (LPS)-induced preterm labor in 15-day pregnant BALB/c mice? Resveratrol prevented the LPS-induced onset of preterm labor in 64% of the cases and showed anti-inflammatory and tocolytic effects by downregulating COX-2 and iNOS expression and NOS activity, and by changing the uterine prostaglandin and endocannabinoid profiling. Genital tract infections by Gram-negative bacteria are a common complication in human pregnancy and have been shown to increase risk of preterm delivery. Bacterial LPS elicits a strong maternal inflammatory response that results in preterm delivery and fetal death in a murine model endotoxin-induced preterm labor. An in vivo animal study was conducted. On Day 15 of pregnancy, mice received at 8:00 h a dose of vehicle (40% ethanol in saline solution) or resveratrol (3 mg/kg in vehicle) via oral gavage followed by two doses of LPS or vehicle administered intraperitoneally (i.p.), the first one at 10:00 h (0.17 mg/kg in 0.1 ml of sterile saline solution) and the second at 13:00 h (0.5 mg/kg in 0.1 ml of sterile saline solution). The mice were closely observed for any signs of morbidity (piloerection, decreased movement, and diarrhea), vaginal bleeding or preterm delivery. The beginning of preterm delivery was defined by early delivery of the first pup. Normal term labor occurs on Day 19 of gestation. Time of labor, pregnancy outcome and morphological features were evaluated after LPS and/or resveratrol administration. Uterine stripes were collected 5 h after the last LPS injection and prostaglandin and endocannabinoid profiling was analyzed by mass spectrometry. Nitric oxide synthase (NOS) activity was measured by radioconversion assay. Cyclooxygenase-2 (Cox-2) and 15-hydroxyprostaglandin dehydrogenase (15-Pgdh) mRNA levels were analyzed by RT-PCR whilst the protein expression of inducible nitric oxide synthase (iNOS), COX-1 and COX-2 were studied by western blot. In vivo treatment of 15-day pregnant BALB/c mice with resveratrol prevented the LPS-induced preterm birth in 64% of the cases, whereas only 15% of mice with LPS alone escaped preterm birth. Treatment with resveratrol resulted in a reduced NOS activity (P < 0.05) in the uterus of LPS-treated mice. Similarly, resveratrol reduced the expression of LPS-induced pro-inflammatory agents such as iNOS (P < 0.05), COX-2 (P < 0.05), prostaglandin E2 (PGE2) (P < 0.05) and anandamide (AEA) (P < 0.05). Moreover, resveratrol administration resulted in changes in the uterine endocannabinoid profiling altered by LPS. N/A. Since our experimental design involves the use of mice, the extrapolation of the results presented here to humans is limited. Our findings provide evidence for the tocolytic effects of resveratrol. Dr Ana María Franchi was funded by Agencia Nacional para la Promoción Científica y Tecnológica (PICT 2013/0097) and by Consejo Nacional de Investigaciones Científicas y Técnicas (PIP 2012/0061). Dr Heather B. Bradshaw was funded by NIH (DA006668). The authors have no competing interests. © The Author 2017. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Coming out ahead: the cost effectiveness of external cephalic version using spinal anesthesia

PubMed Central

2014-01-01

Breech presentation is encountered in 3 to 4% of term pregnancies and has been a significant driver of the increased rate of cesarean deliveries over the last 4 decades. External cephalic version (ECV) is recommended at term by most professional organizations in an effort to reduce the prospect of cesarean deliveries. The authors propose the use of regional anesthesia to increase efficacy and reduce cost in the care of patients who undergo ECV in an effort to convert a breech presentation to a vertex counterpart. Despite emerging evidence of the advantages, obstacles to more comprehensive implementation of this approach continue to exist, which include patient acceptance, provider experience, and safety concerns. The addition of tocolytics and use of regional anesthesia for secondary ECV efforts have also been considered as options to increase success and reduce cost. This is a commentary on http://www.ijhpr.org/content/3/1/5. PMID:24565024

Interventions to help external cephalic version for breech presentation at term.

PubMed

Hofmeyr, G J

2004-01-01

Breech presentation places a fetus at increased risk. The outcome for the baby is improved by planned caesarean section compared with planned vaginal delivery. External cephalic version attempts to reduce the chances of breech presentation at birth, but is not always successful. Tocolytic drugs to relax the uterus as well as other methods have been used in an attempt to facilitate external cephalic version at term. To assess the effects of routine tocolysis, fetal acoustic stimulation, epidural or spinal analgesia and transabdominal amnioinfusion for external cephalic version at term on successful version and measures of pregnancy outcome. The Cochrane Pregnancy and Childbirth Group trials register (September 2003) and the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 3, 2003) were searched. Randomised and quasi-randomised trials comparing routine versus selective or no tocolysis; fetal acoustic stimulation in midline fetal spine positions versus dummy or no stimulation; epidural or spinal analgesia versus no regional analgesia; or transabdominal amnioinfusion versus no amnioinfusion for external cephalic version at term. The reviewer assessed eligibility and trial quality. In six trials, routine tocolysis with beta-stimulants was associated with fewer failures of external cephalic version (relative risk (RR) 0.74, 95% confidence interval (CI) 0.64 to 0.87). The reduction in non-cephalic presentations at birth was not statistically significant. Caesarean sections were reduced (RR 0.85, 95% CI 0.72 to 0.99). In four small trials, sublingual nitroglycerine used as a tocolytic was associated with significant side-effects, and was not found to be effective. Fetal acoustic stimulation in midline fetal spine positions was associated with fewer failures of external cephalic version at term (RR 0.17, 95% CI 0.05 to 0.60). With epidural or spinal analgesia, external cephalic version failure, non-cephalic births and caesarean sections were reduced in two trials but not the other. The overall differences were not statistically significant. No randomised trials of transabdominal amnioinfusion for external cephalic version at term were located. Routine tocolysis appears to reduce the failure rate of external cephalic version at term. There is not enough evidence to evaluate the use of fetal acoustic stimulation in midline fetal spine positions, nor of epidural or spinal analgesia. Large volume intravenous preloading may have contributed to the effectiveness demonstrated in two of the latter trials.

High-order multiple gestations.

PubMed

Elliott, John P

2005-10-01

Infertility treatments have produced an increase in multiple gestations with twins accounting for 3.3% of births in the United States in 2002. Over that same time period, premature deliveries increased from 10.7% in 1992 to 12.1% in 2002. High-order multiple gestations have also increased, and virtually all of those deliver prematurely. Clinicians are facing the challenge of managing these complicated pregnancies. Neonatal outcome will primarily depend on the gestational age at delivery and the birth weight of the babies. Care is directed at aggressively and proactively preventing preterm delivery. Ultrasound assessments are made frequently to assess fetal anatomical abnormalities, nuchal translucency, fetal growth, cervical length, amniotic fluid, and biophysical profile. Stress reduction and activity reduction will decrease uterine activity, and tocolytic drugs are employed to decrease background contractions to reduce preterm labor (PTL). Fetal fibronectin testing helps predict risk of PTL, and magnesium sulfate tocolysis is used in aggressive dosing to arrest PTL if it occurs. Outcomes are presented and discussed. Successful outcomes are not only possible, but probable.

Setting research priorities to improve global newborn health and prevent stillbirths by 2025

PubMed Central

Yoshida, Sachiyo; Martines, José; Lawn, Joy E; Wall, Stephen; Souza, Joăo Paulo; Rudan, Igor; Cousens, Simon; Aaby, Peter; Adam, Ishag; Adhikari, Ramesh Kant; Ambalavanan, Namasivayam; Arifeen, Shams EI; Aryal, Dhana Raj; Asiruddin, Sk; Baqui, Abdullah; Barros, Aluisio JD; Benn, Christine S; Bhandari, Vineet; Bhatnagar, Shinjini; Bhattacharya, Sohinee; Bhutta, Zulfiqar A; Black, Robert E; Blencowe, Hannah; Bose, Carl; Brown, Justin; Bührer, Christoph; Carlo, Wally; Cecatti, Jose Guilherme; Cheung, Po–Yin; Clark, Robert; Colbourn, Tim; Conde–Agudelo, Agustin; Corbett, Erica; Czeizel, Andrew E; Das, Abhik; Day, Louise Tina; Deal, Carolyn; Deorari, Ashok; Dilmen, Uğur; English, Mike; Engmann, Cyril; Esamai, Fabian; Fall, Caroline; Ferriero, Donna M; Gisore, Peter; Hazir, Tabish; Higgins, Rosemary D; Homer, Caroline SE; Hoque, DE; Irgens, Lorentz; Islam, MT; de Graft–Johnson, Joseph; Joshua, Martias Alice; Keenan, William; Khatoon, Soofia; Kieler, Helle; Kramer, Michael S; Lackritz, Eve M; Lavender, Tina; Lawintono, Laurensia; Luhanga, Richard; Marsh, David; McMillan, Douglas; McNamara, Patrick J; Mol, Ben Willem J; Molyneux, Elizabeth; Mukasa, G. K; Mutabazi, Miriam; Nacul, Luis Carlos; Nakakeeto, Margaret; Narayanan, Indira; Olusanya, Bolajoko; Osrin, David; Paul, Vinod; Poets, Christian; Reddy, Uma M; Santosham, Mathuram; Sayed, Rubayet; Schlabritz–Loutsevitch, Natalia E; Singhal, Nalini; Smith, Mary Alice; Smith, Peter G; Soofi, Sajid; Spong, Catherine Y; Sultana, Shahin; Tshefu, Antoinette; van Bel, Frank; Gray, Lauren Vestewig; Waiswa, Peter; Wang, Wei; Williams, Sarah LA; Wright, Linda; Zaidi, Anita; Zhang, Yanfeng; Zhong, Nanbert; Zuniga, Isabel; Bahl, Rajiv

2016-01-01

Background In 2013, an estimated 2.8 million newborns died and 2.7 million were stillborn. A much greater number suffer from long term impairment associated with preterm birth, intrauterine growth restriction, congenital anomalies, and perinatal or infectious causes. With the approaching deadline for the achievement of the Millennium Development Goals (MDGs) in 2015, there was a need to set the new research priorities on newborns and stillbirth with a focus not only on survival but also on health, growth and development. We therefore carried out a systematic exercise to set newborn health research priorities for 2013–2025. Methods We used adapted Child Health and Nutrition Research Initiative (CHNRI) methods for this prioritization exercise. We identified and approached the 200 most productive researchers and 400 program experts, and 132 of them submitted research questions online. These were collated into a set of 205 research questions, sent for scoring to the 600 identified experts, and were assessed and scored by 91 experts. Results Nine out of top ten identified priorities were in the domain of research on improving delivery of known interventions, with simplified neonatal resuscitation program and clinical algorithms and improved skills of community health workers leading the list. The top 10 priorities in the domain of development were led by ideas on improved Kangaroo Mother Care at community level, how to improve the accuracy of diagnosis by community health workers, and perinatal audits. The 10 leading priorities for discovery research focused on stable surfactant with novel modes of administration for preterm babies, ability to diagnose fetal distress and novel tocolytic agents to delay or stop preterm labour. Conclusion These findings will assist both donors and researchers in supporting and conducting research to close the knowledge gaps for reducing neonatal mortality, morbidity and long term impairment. WHO, SNL and other partners will work to generate interest among key national stakeholders, governments, NGOs, and research institutes in these priorities, while encouraging research funders to support them. We will track research funding, relevant requests for proposals and trial registers to monitor if the priorities identified by this exercise are being addressed. PMID:26401272

Setting research priorities to improve global newborn health and prevent stillbirths by 2025.

PubMed

Yoshida, Sachiyo; Martines, José; Lawn, Joy E; Wall, Stephen; Souza, Joăo Paulo; Rudan, Igor; Cousens, Simon; Aaby, Peter; Adam, Ishag; Adhikari, Ramesh Kant; Ambalavanan, Namasivayam; Arifeen, Shams Ei; Aryal, Dhana Raj; Asiruddin, Sk; Baqui, Abdullah; Barros, Aluisio Jd; Benn, Christine S; Bhandari, Vineet; Bhatnagar, Shinjini; Bhattacharya, Sohinee; Bhutta, Zulfiqar A; Black, Robert E; Blencowe, Hannah; Bose, Carl; Brown, Justin; Bührer, Christoph; Carlo, Wally; Cecatti, Jose Guilherme; Cheung, Po-Yin; Clark, Robert; Colbourn, Tim; Conde-Agudelo, Agustin; Corbett, Erica; Czeizel, Andrew E; Das, Abhik; Day, Louise Tina; Deal, Carolyn; Deorari, Ashok; Dilmen, Uğur; English, Mike; Engmann, Cyril; Esamai, Fabian; Fall, Caroline; Ferriero, Donna M; Gisore, Peter; Hazir, Tabish; Higgins, Rosemary D; Homer, Caroline Se; Hoque, D E; Irgens, Lorentz; Islam, M T; de Graft-Johnson, Joseph; Joshua, Martias Alice; Keenan, William; Khatoon, Soofia; Kieler, Helle; Kramer, Michael S; Lackritz, Eve M; Lavender, Tina; Lawintono, Laurensia; Luhanga, Richard; Marsh, David; McMillan, Douglas; McNamara, Patrick J; Mol, Ben Willem J; Molyneux, Elizabeth; Mukasa, G K; Mutabazi, Miriam; Nacul, Luis Carlos; Nakakeeto, Margaret; Narayanan, Indira; Olusanya, Bolajoko; Osrin, David; Paul, Vinod; Poets, Christian; Reddy, Uma M; Santosham, Mathuram; Sayed, Rubayet; Schlabritz-Loutsevitch, Natalia E; Singhal, Nalini; Smith, Mary Alice; Smith, Peter G; Soofi, Sajid; Spong, Catherine Y; Sultana, Shahin; Tshefu, Antoinette; van Bel, Frank; Gray, Lauren Vestewig; Waiswa, Peter; Wang, Wei; Williams, Sarah LA; Wright, Linda; Zaidi, Anita; Zhang, Yanfeng; Zhong, Nanbert; Zuniga, Isabel; Bahl, Rajiv

2016-06-01

In 2013, an estimated 2.8 million newborns died and 2.7 million were stillborn. A much greater number suffer from long term impairment associated with preterm birth, intrauterine growth restriction, congenital anomalies, and perinatal or infectious causes. With the approaching deadline for the achievement of the Millennium Development Goals (MDGs) in 2015, there was a need to set the new research priorities on newborns and stillbirth with a focus not only on survival but also on health, growth and development. We therefore carried out a systematic exercise to set newborn health research priorities for 2013-2025. We used adapted Child Health and Nutrition Research Initiative (CHNRI) methods for this prioritization exercise. We identified and approached the 200 most productive researchers and 400 program experts, and 132 of them submitted research questions online. These were collated into a set of 205 research questions, sent for scoring to the 600 identified experts, and were assessed and scored by 91 experts. Nine out of top ten identified priorities were in the domain of research on improving delivery of known interventions, with simplified neonatal resuscitation program and clinical algorithms and improved skills of community health workers leading the list. The top 10 priorities in the domain of development were led by ideas on improved Kangaroo Mother Care at community level, how to improve the accuracy of diagnosis by community health workers, and perinatal audits. The 10 leading priorities for discovery research focused on stable surfactant with novel modes of administration for preterm babies, ability to diagnose fetal distress and novel tocolytic agents to delay or stop preterm labour. These findings will assist both donors and researchers in supporting and conducting research to close the knowledge gaps for reducing neonatal mortality, morbidity and long term impairment. WHO, SNL and other partners will work to generate interest among key national stakeholders, governments, NGOs, and research institutes in these priorities, while encouraging research funders to support them. We will track research funding, relevant requests for proposals and trial registers to monitor if the priorities identified by this exercise are being addressed.

Preterm premature ruptured membranes: a randomized trial of steroids after treatment with antibiotics.

PubMed

Lewis, D F; Brody, K; Edwards, M S; Brouillette, R M; Burlison, S; London, S N

1996-11-01

To assess the effectiveness of corticosteroids in patients with preterm premature rupture of membranes (PROM) after treatment with a broad-spectrum antibiotic, ampicillin-sulbactam. A randomized clinical trial of corticosteroids in patients with preterm PROM was undertaken after treating these patients for a minimum of 12 hours with ampicillin-sulbactam. No digital vaginal examinations were performed on these patients. Antibiotics were continued for 7 days and the steroids were repeated weekly. No tocolytics were used. The primary outcome measure was the incidence of respiratory distress syndrome (RDS). Secondary outcome measures included latency period and neonatal and maternal infectious morbidity. Seventy-seven patients were enrolled and data about their pregnancies were analyzed. No statistically significant difference in latency period was noted (14.7 days in the steroid group, 15.8 days in the no-steroid group). Both neonatal and maternal infectious morbidity were similar. A significant reduction in the incidence of RDS (18.4 versus 43.6%, P = .03) were observed in the steroid group. These data suggest that treating preterm PROM patients with a broad-spectrum antibiotic before corticosteroids decreases RDS without apparent adverse sequelae.

Progesterone in women with arrested premature labor, a report of a randomised clinical trial and updated meta-analysis.

PubMed

Wood, Stephen; Rabi, Yacov; Tang, Selphee; Brant, Rollin; Ross, Susan

2017-08-02

Progesterone may be effective in prevention of premature birth in some high risk populations. Women with arrested premature labor are at risk of recurrent labor and maintenance therapy with standard tocolytics has not been successful. Randomized double blinded clinical trial of daily treatment with 200 mg vaginal progesterone in women with arrested premature labor and an updated meta-analysis. The clinical trial was terminated early after 41 women were enrolled. Vaginal progesterone treatment did not change the median gestational age at delivery: 36+2 weeks versus 36+4 weeks, p = .865 nor increase the mean latency to delivery: 44.5 days versus 46.6 days, p = .841. In the updated meta-analysis, progesterone treatment did reduce delivery <37 weeks gestation and increase latency to delivery, but this treatment effect was not evident in the high quality trials: (OR 1.23, 95% CI 0.91, 1.67) and (-0.95 days, 95% CI -5.54, 3.64) respectively. Progesterone is not effective for preventing preterm birth following arrested preterm labor.

Twins: prevalence, problems, and preterm births.

PubMed

Chauhan, Suneet P; Scardo, James A; Hayes, Edward; Abuhamad, Alfred Z; Berghella, Vincenzo

2010-10-01

The rate of twin pregnancies in the United States has stabilized at 32 per 1000 births in 2006. Aside from determining chorionicity, first-trimester screening and second-trimester ultrasound scanning should ascertain whether there are structural or chromosomal abnormalities. Compared with singleton births, genetic amniocentesis-related loss at <24 weeks of gestation for twin births is higher (0.9% vs 2.9%, respectively). Selective termination for an anomalous fetus is an option, although the pregnancy loss rate is 7% at experienced centers. For singleton and twin births for African American and white women, approximately 50% of preterm births are indicated; approximately one-third of these births are spontaneous, and 10% of the births occur after preterm premature rupture of membranes. From 1989-2000, the rate of preterm twin births increased, for African American and white women alike, although the perinatal mortality rate has actually decreased. As with singleton births, tocolytics should be used judiciously and only for a limited time (<48 hours) in twin births. Administration of antenatal corticosteroids is an evidence-based recommendation. Copyright © 2010 Mosby, Inc. All rights reserved.

Triplet pregnancies: perinatal outcome evolution.

PubMed

Almeida, Patrícia; Domingues, Ana Patrícia; Belo, Adriana; Fonseca, Etelvina; Moura, Paulo

2014-09-01

To evaluate the obstetric and perinatal outcomes evolution of triplet pregnancies. A prospective observational study was conducted in triplet pregnancies delivered over 16 years in a tertiary obstetric center with differentiated perinatal support. Evaluation of demographic factors, obstetric complications, gestational age at delivery, mode of delivery, birth weight and immediate newborn outcome were done over a 16 years period. A global characterization of the sample was performed considering the listed parameters. Variables were categorized in three groups according to year of occurrence: 1996-2000, 2001-2006, 2007-2011, and all parameters were compared. Of the 33 triplets included, 72.7% resulted from induced pregnancies. All except one patient received prenatal corticosteroids and five received tocolytics. All women delivered prenatally and no significant differences were seen in the mean gestational age at delivery or birth weight towards time. There were three intrauterine fetal deaths. Neonatal immediate outcomes were not significantly different over the years. Despite remarkable progresses in perinatal and neonatal cares, no noticeable impact in triplet gestations' outcomes was seen, sustaining that triplets should be avoided due to their great risk of prematurity and neonatal morbidities, either by limiting the numbers of embryos transferred or by fetal reduction.

Neurodevelopmental Outcomes of Extremely Low Birth Weight Infants Ventilated With Continuous Positive Airway Pressure vs. Mechanical Ventilation

PubMed Central

Thomas, Cameron W.; Meinzen-Derr, Jareen; Hoath, Steven B.; Narendran, Vivek

2012-01-01

OBJECTIVE To compare continuous positive airway pressure (CPAP) vs. traditional mechanical ventilation (MV) at 24 h of age as predictors of neurodevelopmental (ND) outcomes in extremely low birth weight (ELBW) infants at 18-22 mo corrected gestational age (CGA). METHODS Infants ≤ 1000g birth weight born from January 2000 through December 2006 at two hospitals at the Cincinnati site of the National Institute of Child Health and Human Development Neonatal Research Network were evaluated comparing CPAP (N = 198) vs. MV (N = 109). Primary outcomes included the Bayley Score of Infant Development Version II (BSID-II), presence of deafness, blindness, cerebral palsy, bronchopulmonary dysplasia and death. RESULTS Ventilatory groups were similar in gender, rates of preterm prolonged rupture of membranes, antepartum hemorrhage, use of antenatal antibiotics, steroids, and tocolytics. Infants receiving CPAP weighed more, were older, were more likely to be non-Caucasian and from a singleton pregnancy. Infants receiving CPAP had better BSID-II scores, and lower rates of BPD and death. CONCLUSIONS After adjusting for acuity differences, ventilatory strategy at 24 h of age independently predicts long-term neurodevelopmental outcome in ELBW infants. PMID:21853318

SSR126768A (4-chloro-3-[(3R)-(+)-5-chloro-1-(2,4-dimethoxybenzyl)-3-methyl-2-oxo-2,3-dihydro-1H-indol-3-yl]-N-ethyl-N-(3-pyridylmethyl)-benzamide, hydrochloride): a new selective and orally active oxytocin receptor antagonist for the prevention of preterm labor.

PubMed

Serradeil-Le Gal, Claudine; Valette, Gérard; Foulon, Loïc; Germain, Guy; Advenier, Charles; Naline, Emmanuel; Bardou, Marc; Martinolle, Jean-Pierre; Pouzet, Brigitte; Raufaste, Danielle; Garcia, Corinne; Double-Cazanave, Eléonore; Pauly, Maxime; Pascal, Marc; Barbier, Alain; Scatton, Bernard; Maffrand, Jean-Pierre; Le Fur, Gérard

2004-04-01

4-chloro-3-[(3R)-(+)-5-chloro-1-(2,4-dimethoxybenzyl)-3-methyl-2-oxo-2,3-dihydro-1H-indol-3-yl]-N-ethyl-N-(3-pyridylmethyl)benzamide, hydrochloride (SSR126768A), a new potent and selective, orally active oxytocin (OT) receptor antagonist was characterized in several biochemical and pharmacological models. In binding studies, SSR126768A showed nanomolar affinity for rat and human recombinant and native OT receptors (K(i) = 0.44 nM) and exhibited much lower affinity for V(1a), V(1b), and V(2) receptors. In addition, it did not interact with a large number of other receptors, enzymes, and ion channels (1 microM). In autoradiographic experiments performed on at-term human pregnant uterus sections, SSR126768A dose dependently displaced [I(125)]d(CH(2))(5)[Tyr(Me)(2), Thr(4), Orn(8) (125)I-Tyr-NH(2)(9)]VT in situ labeling to OT receptors highly expressed in these tissues. In functional studies, SSR126768A behaved as a full antagonist and potently antagonized OT-induced intracellular Ca(2+) increase (K(i) = 0.50 nM) and prostaglandin release (K(i) = 0.45 nM) in human uterine smooth muscle cells. In rat isolated myometrium, OT-induced uterine contractions were competitively antagonized by SSR126768A (pA(2) = 8.47). Similarly, in human pregnant myometrial strips, SSR126768A inhibited the contractile uterine response to OT. In conscious telemetrated rats, oral administration of SSR126768A (1-10 mg/kg) produced a competitive inhibition of the dose response to OT on uterine contractions up to 24 h at 3 mg/kg p.o.; no tachyphylaxis was observed after 4-day repeated treatment. Finally, SSR126768A (30 mg/kg p.o.) significantly delayed parturition in pregnant rats in labor similar to ritodrine (10 mg/kg p.o.). Thus, SSR126768A is a potent, highly selective, orally active OT receptor antagonist with a long duration of action. This molecule could find therapeutic application as a tocolytic agent for acute and chronic oral management of preterm labor.

A case of sudden onset of thyroid storm just before cesarean section manifesting congestive heart failure and pulmonary edema.

PubMed

Sugiyama, Yuki; Tanaka, Ryusuke; Yoshiyama, Yuki; Ichino, Takashi; Hishinuma, Norimasa; Shimizu, Sari; Imai, Noriko; Mitsuzawa, Kunihiro; Kawamata, Mikito

2017-01-01

Since acute respiratory failure (ARF) is a life-threatening complication, particularly in the gestational period, differential diagnosis and rapid treatment are required. Among the various causes of sudden onset of ARF, thyroid storm is a rare cause in a parturient complicated with well-controlled hyperthyroidism. In this case report, we describe a parturient with hyperthyroidism in whom a thyroid storm manifesting congestive heart failure and pulmonary edema developed just before an emergency ceasarean section, even though hyperthyroidism was well-controlled with antithyroid drugs. A 36-year-old pregnant woman was diagnosed as having clinical chorioamnionitis, and an emergency cesarean section was performed at 25 weeks of pregnancy. She had a complication of hyperthyroidism accompanied by mild mitral regurgitation, and she had been treated with methimazole. She was treated with ritodrine and MgSO 4 for the threat of premature delivery. At the preoperative consultation, her percutaneous oxygen saturation (SpO 2 ) was 98% on room air. When she was admitted to the operating room, her heart rate and blood pressure were 130 beats/min and 196/78 mmHg, respectively. SpO 2 was 88% on room air without any symptoms; however, just after starting oxygen administration via a facemask, she complained of severe respiratory distress and became agitated. Partial pressure of arterial oxygen was 108 mmHg with an inspiratory oxygen fraction of 1.0. Chest radiography revealed pulmonary congestion, and transesophageal echocardiography revealed normal right ventricular function without an embolus and severe mitral regurgitation with preserved left ventricular function. Contrast-enhanced computed tomography after the operation revealed no pulmonary embolus but revealed a pulmonary effusion, and free triiodothyronine level was increased at the onset of dyspnea. Therefore, we diagnosed the causes of sudden onset of dyspnea as pulmonary edema and congestive heart failure induced by a thyroid storm. Sudden onset of a thyroid storm just before a cesarean section occurred in a patient with several risk factors of thyroid storm and pulmonary edema, including pregnancy, treatment with tocolytic agents, and infection. The involvement of these multiple factors was considered to be the cause of the sudden onset of the thyroid storm and the cause of rapidly progressive pulmonary edema.

Association between ß2-adrenergic receptor gene polymorphisms and adverse events of ritodrine in the treatment of preterm labor: a prospective observational study.

PubMed

Chung, Jee Eun; Choi, Soo An; Hwang, Han Sung; Park, Jin Young; Lee, Kyung Eun; Yee, Jeong; Kim, Young Ju; Gwak, Hye Sun

2017-11-13

Ritodrine, a tocolytic β2-agonist, has been used extensively in Europe and Asia despite its safety concerns. This study was designed to identify associations between β2-adrenergic receptor (ADRB2) polymorphisms and adverse drug events (ADEs) in patients with preterm labor treated with ritodrine. This follow-up study was prospectively conducted at Ewha Womans University Mokdong Hospital in Korea. Five single nucleotide polymorphisms (SNPs) of the ADRB2 gene (rs1042713, rs1042714, rs1042717, rs1042718, and rs1042719) were analyzed in 186 pregnant women with preterm labor. Patients with the AA genotype of rs1042717 had significantly lower incidence of ADEs compared to those with the G allele (p = 0.009). In multivariate analysis, one of the predictors of ADEs was the maximum infusion rate of ritodrine (AOR 4.47, 95% CI 1.31-15.25). Rs1042719 was also a significant factor for ritodrine-induced ADEs. The CC genotype carriers had 78% decreased risk of ADEs compared to those with other genotypes. This study demonstrates that ADEs induced by ritodrine are associated with ADRB2 gene polymorphisms, as well as the infusion rate of ritodrine in pregnant women with preterm labor.

The T/QRS ratio values in pregnancies complicated by threatened preterm labour treated with intravenous infusions of fenoterol.

PubMed

Fuchs, Tomasz; Pomorski, Michał; Grobelak, Krzysztof; Zimmer, Mariusz

2015-07-01

To evaluate values of foetal T/QRS ratios in pregnancies complicated by threatened preterm labour treated with intravenous infusions of fenoterol using non-invasive methods with transabdominal electrodes. The study group consisted of 451 Caucasian women (63 preterm pregnancies and 327 healthy controls) whose pregnancies ranged from 28 to 37 gestational weeks. Foetal electrocardiograms were recorded and T/QRS ratios were calculated by KOMPOREL software (ITAM, Zabrze, Poland). The first recording was performed 30 min after the start of fenoterol infusion and the second 2 days after finishing tocolysis. T/QRS ratio variables were calculated. One-way analysis of variance was carried out. Significantly higher mean values of the T/QRS ratio were observed in pregnancies during tocolytic treatment in comparison to controls and pregnancies after tocolysis (P=0.0158 and P=0.0071, respectively). The T/QRS ratio values fall again shortly after finishing intravenous tocolysis. The T/QRS ratio is one of the methods used for non-invasive foetal distress assessment that can be used in antepartum foetal monitoring in complicated pregnancies. Raised values of the T/QRS ratio in the foetus during tocolysis with fenoterol and next its fall to values observed in physiological pregnancies may indicate transient worsening of fetal well-being, however, additional research is required.

Patient satisfaction with childbirth after external cephalic version.

PubMed

Bogner, Gerhard; Hammer, Barbara Eva; Schausberger, Christiane; Fischer, Thorsten; Reisenberger, Klaus; Jacobs, Volker

2014-03-01

To assess acceptance and impact of external cephalic version (ECV) for breech presentation at term on maternal satisfaction with childbirth. Retrospective study on n = 131 women with breech presentation comparing maternal satisfaction after ECV and consecutive childbirth (n = 66; 50.4% of these successful attempts in n = 33; 50%) against the group without ECV and primary caesarean section (CS) (n = 65; 49.6%) instead using a questionnaire. Women with successful ECV tolerated side effects of the intervention better than after unsuccessful ECV (pain, tocolytics, mental and physical state, for all p < 0.001). They were not more satisfied with childbirth than women who experienced an unsuccessful ECV (p = 0.37). However, they would undergo the procedure again (p = 0.003) and would recommend it to other women (p < 0.001). Only women with spontaneous vaginal deliveries after successful version were more satisfied with childbirth than women with planned CS (p = 0.05). Women with version attempts tend to perceive childbirth as being less problematic with fewer complications (9.5 vs. 19%, p = 0.12). Unsuccessful ECVs had no negative impact on satisfaction with childbirth (p = 0.072). Attempting ECV seems to be an option for increasing the rate of vaginal births with breech presentation without negative impact on maternal satisfaction regarding consecutive childbirth.

Delay in treatment of biliary disease during pregnancy increases morbidity and can be avoided with safe laparoscopic cholecystectomy.

PubMed

Muench, J; Albrink, M; Serafini, F; Rosemurgy, A; Carey, L; Murr, M M

2001-06-01

Recent reports indicate that laparoscopic cholecystectomy in pregnancy is safe. The aim of this study was to evaluate whether delays in definitive treatment of symptomatic cholelithiasis increase morbidity. We reviewed the records of 16 women who underwent laparoscopic cholecystectomy during pregnancy between 1992 and 1999. Mean age was 24 +/- 5 years (mean +/- standard error). Symptom onset was during the first trimester in nine patients, second trimester in six patients, and third trimester in one patient. Patients had abdominal pain (93%), nausea (93%), emesis (80%), and fever (66%) for a median of 45 days (range 1-195 days) before cholecystectomy. Nine of 11 women who underwent cholecystectomy more than 5 weeks after onset of symptoms experienced recurrent attacks necessitating 15 hospital admissions and four emergency room visits. Moreover four women who developed symptoms in the first and second trimesters but whose operations were delayed to the third trimester had 11 hospital admissions and four emergency room visits; three of those four (75%) women developed premature contractions necessitating tocolytics. Cholecystectomy was completed laparoscopically in 14 women. There was no hospital infant or maternal mortality or morbidity. We recommend prompt laparoscopic cholecystectomy in pregnant women with symptomatic biliary disease because it is safe and it reduces hospital admissions and frequency of premature labor.

Ultrasonographic wall thickness measurement of the upper and lower uterine segments in the prediction of the progress of preterm labour.

PubMed

Sayed Ahmed, W A; Madny, E H; Habash, Y H; Ibrahim, Z M; Morsy, A G K; Said, M E

2015-01-01

To assess the role of ultrasonographic measurement of the upper and lower uterine segments wall thickness in predicting the progress of preterm labour in patients presenting with preterm labour pains. Fifty pregnant women presenting at Obstetrics Department - Suez Canal University, Egypt with regular lower abdominal pains and diagnosed as having preterm labour were enrolled in the study. Measurements of the upper and lower uterine segments wall thickness by transabdominal ultrasonography in-between contractions and with full bladder were taken. The upper/lower uterine wall thickness ratio was calculated and correlated to the progress of the preterm labour and to the response to tocolytics. The ultrasonographic upper/lower uterine wall thickness ratio was directly related to the progress of preterm delivery (PTD). The change in this ratio is correlated inversely with the response to tocolysis. Using the ROC curve, when the upper/lower uterine wall thickness ratio was ≤ 1.26 the sensitivity was 94.74 and the specificity was 100.00, and when the ratio was ≤ 1.52 the sensitivity was 100.00 and the specificity was 83.33. These data may serve as a baseline ultrasonographic reference values for further studies in prediction the progress of preterm labour in patients presenting with preterm labour pains.

Effect of cerclage on labor course and obstetric outcome: a case-control study.

PubMed

Shin, Jae Eun; Shin, Jong Chul; Kim, Sa Jin; Lee, Young

2012-09-01

The purpose of this study was to evaluate the effects of cervical cerclage on labor course and obstetric outcome. In a retrospective case-control study, we compared labor course, total labor duration, and obstetric complications in 127 women who received cervical cerclage with 254 controls. There was no significant difference in the duration of the first stage of labor (477 ± 576 vs. 373 ± 437 min, p = 0.075) or the second stage of labor (18 ± 17 vs. 20 ± 19 min, p = 0.287) between the 2 groups. In the multivariate analysis, women in the cerclage group were found to be significantly more likely to have a prolonged latent phase (odds ratio [OR], 2.802; 95% confidence interval [CI], 1.103-7.120; p = 0.030), cervical laceration (OR, 15.984; 95% CI, 3.169-80.624; p = 0.001), and treatment with tocolytics (OR, 2.580; 95% CI, 1.217-5.468; p = 0.013) than the control group. No significant difference was noted in cesarean delivery rate. Cervical cerclage is more likely to be associated with a prolonged latent phase and minor obstetric complications, but not with a difference in the total duration of labor or increased cesarean delivery rate.

Prenatal surgery for congenital diaphragmatic hernia.

PubMed

Au-Yeung, Jeff Ying-Kit; Chan, Kwong-Leung

2003-10-01

Congenital diaphragmatic hernia (CDH) has a mortality rate of up to 77% despite optimal pre- and postnatal care. Fetuses with liver herniation, a low lung-to-head ratio, and an early diagnosis before 24 weeks have a particularly poor prognosis. In utero open repair of these fetuses does not improve patient survival. The PLUG (Plug the Lung Until it Grows) technique was reported to be able to reverse pulmonary hypoplasia in CDH. A foam plug or a titanium clip is used and the trachea can be unplugged using Ex Utero Intrapartum Tracheoplasty (EXIT) at birth. Since hysterotomy causes premature labour, a video-fetoscopic intrauterine technique of tracheal occlusion called Fetendo-PLUG was developed. Compared to those who receive standard postnatal care or fetal tracheal occlusion via open hysterotomy, patients who undergo Fetendo-PLUG are reported to have a higher survival rate of 75% and fewer fetal and maternal complications. A recent refinement is to use a detachable balloon for intratracheal occlusion through a single 5 mm port under real-time ultrasound guidance. Without the need for neck dissection, injury to the recurrent laryngeal nerves and trachea and vocal cord paresis can be minimized. The result of this form of treatment for CDH is promising, but further refinement of fetal instrumentation and development of effective tocolytic drugs are still required.

Perspectives in the prevention of premature birth.

PubMed

Ancel, Pierre-Yves

2004-11-15

Obstetric and neonatal interventions have improved the survival of preterm infants, but there has not been an equivalent reduction in long-term neurological disability. Thus, some effort must be invested in finding ways of preventing preterm birth. Numerous programmes have been promoted to address the matter of how the frequency of preterm birth could be prevented. Most interventions intended to prevent preterm labour do not have the desired effect, except for antibiotic treatment in cases of asymptomatic bacteriuria or bacterial vaginosis and progesterone administered prophylactically in high-risk women. Tocolytic drugs appear to delay delivery long enough for successful administration of corticosteroids in women in preterm labour, but without decreasing the risk of preterm birth. Some authors promote public health approaches that address all risk factors and affect the entire population of pregnant women, given that prevention programmes directed only at high-risk women have had little effect in preventing preterm births. However, the lack of progress in reducing the frequency of preterm births is also due to our limited understanding of the aetiology of preterm delivery. Although there is growing evidence that infection and neuroendocrine processes are involved, progress has remained slow. Recently, the hypothesis of a genetic predisposition to preterm delivery has been set up. Additional research exploring the pathophysiology of preterm labour is obviously needed, which will hopefully lead to the development of new therapeutic approaches.

Relaxant effect of proton pump inhibitors on in vitro myometrium from pregnant women.

PubMed

Terranova, C; Petrella, C; Improta, G; Severini, C; Signore, F; Damiani, P; Plotti, F; Scarpignato, C; Angioli, R

2014-02-14

In this study we investigate in in vitro myometrial tissue samples of pregnant women: (a) the effects of proton pomp inhibitors (PPIs) (omeprazole, esomeprazole, pantoprazole, lansoprazole and rabeprazole) on spontaneous contractions; (b) the muscle-relaxant efficacy of the most active PPI considered (pantoprazole) in comparison with that of other known tocolytics (nifedipine, atosiban, MgSO4, isoxsuprine); (c) the effect of pantoprazole on contractions induced by calcium (Ca(++)), KCl, oxytocin and prostaglandin (PGE2); (d) the possible mediators of pantoprazole relaxant effect. Organ bath studies were performed on myometrial tissue samples (40×10×10 mm) from pregnant women (38-42 weeks of gestational age) undergoing elective caesarian section. All the PPIs studied reduce the spontaneous contraction of the myometrial smooth muscle. Pantoprazole is the most effective and most potent inhibitor among those analyzed. Pantoprazole also reduces the contractions induced by Ca(++), KCl, oxytocin and PGE2. Neither NO, nor PGs, or the activation of Ca(++)-dependent K(+) currents mediate the muscle-relaxant effect of this PPI. These data, together with the fact that PPIs almost do not present side effects, suggest that these drugs can offer new therapeutic strategies for preterm delivery. Undoubtedly, further investigations and clinical studies are necessary before adding PPIs to the list of drugs available for the treatment of preterm delivery. Copyright © 2013 Elsevier B.V. All rights reserved.

Tocolysis for in utero Surgery: Atosiban Performs Distinctly Better than Magnesium Sulfate.

PubMed

Ochsenbein-Kölble, Nicole; Krähenmann, Franziska; Hüsler, Margret; Meuli, Martin; Moehrlen, Ueli; Mazzone, Lucca; Biro, Peter; Zimmermann, Roland

2017-08-17

To compare tocolysis with magnesium sulfate versus atosiban regarding the occurrence of short-term preterm labor and maternal side effects during and after open fetal myelomeningocele (MMC) repair. A prospective nonrandomized cohort study was performed including 30 fetal MMC cases. The first 15 cases (group 1) received magnesium sulfate according to the MOMS protocol. In the following 15 cases (group 2), magnesium sulfate was substituted by atosiban. Chorioamniotic membrane separation (CMS), premature prelabor rupture of the fetal membranes (PPROM), preterm delivery <3 weeks after fetal MMC repair, and maternal complications due to the tocolytic medication were the major endpoints. In both groups, one CMS but no PPROM was diagnosed <3 weeks after fetal MMC repair. One patient of group 2 delivered <3 weeks after fetal MMC repair because of an intraoperative placental abruption at 25 weeks. All women of group 1 showed an electrolyte imbalance during magnesium sulfate administration. One woman of group 1 developed several episodes of a third-degree atrioventricular block within the first 3 days after fetal surgery. Lethargy was found in all women during magnesium sulfate therapy. No maternal side effects were found under atosiban. The use of atosiban resulted in an almost identical short-term uterine outcome without any serious maternal complications as seen when magnesium sulfate was given. Thus, the authors suggest using atosiban instead of magnesium sulfate in the context of open fetal surgery. © 2017 S. Karger AG, Basel.

48-hours administration of fenoterol in spontaneous preterm labor - does it affect fetal preload?

PubMed

Grzesiak, Mariusz; Forys, Sebastian; Sobczak, Malgorzata; Ahmed, Rehana B; Wilczynski, Jan

2013-01-01

to investigate whether any changes in the preload index (PLI) occur within the first 48 hours of fenoterol intravenous tocolysis. Doppler evaluation of placental and fetal circulation was performed in 36 pregnant women prior to fenoterol administration and after 24/48 hours. Measurements were obtained from a longitudinal section of the inferior vena cava (IVC) and preload index was calculated. To determine changes over time, an all study variable analysis of variance (ANOVA) for repeated measurements, followed by Tukey-Kramer's multiple comparison test was used. The effects of additional clinical covariates were checked. The maternal heart rate values were significantly increased after 24 hours and 48 hours in comparison to pre-treatment values. No significant changes in fetal heart rate were observed during treatment. The fetal IVC PLI values were significantly reduced after 24 hours and 48 hours of treatment. The increase in PLI values when comparing 24 and 48 hours results were not statistically significant. These observations were consistent with ANOVA post-hoc analysis. 48 hours intravenous administration of fenoterol appears not to alter inferior vena cava blood flow by itself. The reduction in PLI values may reflect lower fetal preload conditions during the course of successful tocolytic treatment. Therefore, Doppler IVC PLI measurement should be considered as a possible additional assessment method of effectiveness of treatment. However, other Doppler venous blood flow parameters should be assessed to confirm the results and clarify whether maternal corticosteroids administration may be interfering with the results.

Cross-Species Withdrawal of MCL1 Facilitates Postpartum Uterine Involution in Both the Mouse and Baboon

PubMed Central

Kyathanahalli, Chandrashekara; Marks, Jason; Nye, Kennedy; Lao, Belinda; Albrecht, Eugene D.; Aberdeen, Graham W.; Nathanielsz, Peter W.; Jeyasuria, Pancharatnam

2013-01-01

A successful postpartum involution permits the postnatal uterus to rapidly regain its prepregnancy function and size to ultimately facilitate an ensuing blastocyst implantation. This study investigates the molecular mechanisms that govern the initiation of the involution process by examining the signaling events that occur as the uterus transitions from the pregnant to postnatal state. Using mouse and baboon uteri, we found a remarkable cross-species conservation at the signal transduction level as the pregnant uterus initiates and progresses through the involution process. This study originated with the observation of elevated levels of caspase-3 activation in both the laboring mouse and baboon uterus, which we found to be apoptotic in nature as evidenced by the concurrent appearance of cleaved poly(ADP-ribose) polymerase. We previously defined a nonapoptotic and potential tocolytic role for uterine caspase-3 during pregnancy regulated by increased antiapoptotic signaling mediated by myeloid cell leukemia sequence 1 and X-linked inhibitor of apoptosis. In contrast, this study determined that diminished antiapoptotic signaling in the postpartum uterus allowed for both endometrial apoptotic and myometrial autophagic episodes, which we speculate are responsible for the rapid reduction in size of the postpartum uterus. Using our human telomerase immortalized myometrial cell line and the Simian virus-40 immortalized endometrial cell line (12Z), we demonstrated that the withdrawal of antiapoptotic signaling was also an upstream event for both the autophagic and apoptotic processes in the human uterine myocyte and endometrial epithelial cell. PMID:24140717

Casein kinase 2 inhibition impairs spontaneous and oxytocin-induced contractions in late pregnant mouse uterus.

PubMed

Suhas, K S; Parida, Subhashree; Gokul, Chandrasekaran; Srivastava, Vivek; Prakash, E; Chauhan, Sakshi; Singh, Thakur Uttam; Panigrahi, Manjit; Telang, Avinash G; Mishra, Santosh K

2018-05-01

What is the central question of this study? Does the inhibition of the protein kinase casein kinase 2 (CK2) alter the uterine contractility? What is the main finding and its importance? Inhibition of CK2 impaired the spontaneous and oxytocin-induced contractility in late pregnant mouse uterus. This finding suggests that CK2 is a novel pathway mediating oxytocin-induced contractility in the uterus and thus opens up the possibility for this class of drugs to be developed as a new class of tocolytics. The protein kinase casein kinase 2 (CK2) is a ubiquitously expressed serine or threonine kinase known to phosphorylate a number of substrates. The aim of this study was to assess the effect of CK2 inhibition on spontaneous and oxytocin-induced uterine contractions in 19 day pregnant mice. The CK2 inhibitor CX-4945 elicited a concentration-dependent relaxation in late pregnant mouse uterus. CX-4945 and another selective CK2 inhibitor, apigenin, also inhibited the oxytocin-induced contractile response in late pregnant uterine tissue. Apigenin also blunted the prostaglandin F 2α response, but CX-4945 did not. Casein kinase 2 was located in the lipid raft fractions of the cell membrane, and disruption of lipid rafts was found to reverse its effect. The results of the present study suggest that CK2, located in lipid rafts of the cell membrane, is an active regulator of spontaneous and oxytocin-induced uterine contractions in the late pregnant mouse. © 2018 The Authors. Experimental Physiology © 2018 The Physiological Society.

External cephalic version for singleton breech presentation: proposal of a practical check-list for obstetricians.

PubMed

Indraccolo, U; Graziani, C; Di Iorio, R; Corona, G; Bonito, M; Indraccolo, S R

2015-07-01

External cephalic version (ECV) for breech presentation is not routinely performed by obstetricians in many clinical settings. The aim of this work is to assess to what extent the factors involved in performing ECV are relevant for the success and safety of ECV, in order to propose a practical check-list for assessing the feasibility of ECV. Review of 214 references. Factors involved in the success and risks of ECV (feasibility of ECV) were extracted and were scored in a semi-quantitative way according to textual information, type of publication, year of publication, number of cases. Simple conjoint analysis was used to describe the relevance found for each factor. Parity has the pivotal role in ECV feasibility (relevance 16.6%), followed by tocolysis (10.8%), gestational age (10.6%), amniotic fluid volume (4.7%), breech variety (1.9%), and placenta location (1.7%). Other factors with estimated relevance around 0 (regional anesthesia, station, estimated fetal weight, fetal position, obesity/BMI, fetal birth weight, duration of manoeuvre/number of attempts) have some role in the feasibility of ECV. Yet other factors, with negative values of estimated relevance, have even less importance. From a logical interpretation of the relevance of each factor assessed, ECV should be proposed with utmost prudence if a stringent check-list is followed. Such a check-list should take into account: parity, tocolytic therapy, gestational age, amniotic fluid volume, breech variety, placenta location, regional anesthesia, breech engagement, fetal well-being, uterine relaxation, fetal size, fetal position, fetal head grasping capability and fetal turning capability.

Antenatal calcium channel blocker exposure and subsequent patent ductus arteriosus in extremely low-birth-weight infants.

PubMed

McGuirl, Jennifer; Arzuaga, Bonnie; Lee, Ben H

2012-01-01

This study aimed to assess whether tocolytic fetal exposure to antenatal calcium channel blockers (aCCB) increases the risk for hemodynamically significant patent ductus arteriosus (hsPDA) in extremely low-birth-weight (ELBW) infants. This case-control study investigated ELBW infants (<1,000 g) without cardiac defects in a level 3 neonatal intensive care unit who had survived at least 7 days. Nifedipine was the only aCCB used for this study population. The measurements included the history of aCCB exposure, selected maternal data, hsPDA diagnosis, gestational age at birth, birth weight, mode of delivery, sex, maternal race, location of birth, Apgar scores, and selected neonatal morbidities. The end point of the study was hsPDA, defined as an echocardiographically confirmed PDA with clinical symptoms. A total of 180 infants met the study criteria. The diagnosis was hsPDA for 56% of these patients, 20% of whom had aCCB exposure. Of the infants without hsPDA, 11% had aCCB exposure (p = 0.09). No statistically significant associations were found between aCCB exposure and hsPDA after adjustment for gestational age (odds ratio [OR], 1.5; 95% confidence interval [CI], 0.6-3.7) or for gestational age and cumulative aCCB exposure of 100 mg or more (OR, 2.0; 95% CI, 0.6-6.5). A history of aCCB exposure does not appear to increase hsPDA risk in ELBW infants. Studies using neonatal serum nifedipine concentrations after antenatal exposure should be performed to confirm this conclusion.

A prospective population-based study of 598 cases of PPROM between 24 and 34 weeks' gestation: description, management, and mortality (DOMINOS cohort).

PubMed

Pasquier, Jean-Charles; Rabilloud, Muriel; Picaud, Jean-Charles; Ecochard, René; Claris, Olivier; Gaucherand, Pascal; Collet, Frédéric; Chabert, Pierre; Mellier, Georges

2005-08-01

Description of mothers' characteristics, obstetricians' practices, and PPROM-linked mortality in all 81 maternity hospitals in the Rhône-Alpes Region, over a period of 2 years. Prospective cohort study of 598 women with PPROM between 24 and 34 weeks' gestation, leading to 680 births. At time of PPROM, collection of mothers' socio-economic characteristics, medical and obstetric histories and PPROM circumstances. Collection of perinatal management, neonates' medical status and postnatal referral. The birth rate after PPROM between 24 and 34 weeks' gestation was 0.47% (95% CI: 0.42-0.48). Sixty percent of PPROM occurred before 32 weeks' gestation and 98% of births before 37 weeks. The incidence of previous PPROM was 14.3%. Antibiotics, corticosteroids, and tocolytics were given to 82, 78, and 52% of women, respectively. The rate of antibiotics and antenatal corticosteroids varied with gestational age (lower rates for antibiotics just after the limit of viability (23-24 weeks) and after 32 weeks, higher rates of corticosteroids between 26 and 30 weeks). The PPROM-birth interval became shorter as gestation advanced. The incidence of C-section was 58.7% (n = 270), C-section before labour being the most frequent mode of delivery. Sixty-seven percent of neonates were born in Level-3 hospitals. The overall neonatal mortality rate at 28 days decreased with gestational age at PPROM, and was 17.2% (16/93), 3% (6/200), and 0.41% (1/241) at 24-27, 28-31 and 32-33 weeks of PPROM, respectively. After PPROM, antibiotics and antenatal corticosteroids were widely used in our cohort, and C-section rates were elevated. With that up-to-date management, the perinatal mortality rate was less than 3% following PPROM after 28 weeks' gestation.

External cephalic version facilitation for breech presentation at term.

PubMed

Hofmeyr, G J

2000-01-01

Successful external cephalic version at a late stage of pregnancy was considered to be possible only with the use of tocolytic drugs to relax the uterus. Other methods are also used in an attempt to facilitate external cephalic version at term. The objective of this review was to assess the effects of routine tocolysis, fetal acoustic stimulation, epidural anaesthesia and transabdominal amnioinfusion for external cephalic version at term on successful version and measures of pregnancy outcome. The Cochrane Pregnancy and Childbirth Group trials register and the Cochrane Controlled Trials Register were searched. Date of last search: February 1999. Randomised and quasi-randomised trials comparing routine versus selective tocolysis; fetal acoustic stimulation in midline fetal spine positions versus dummy or no stimulation; epidural analgesia versus no epidural analgesia; or transabdominal amnioinfusion versus no amnioinfusion for external cephalic version at term. Eligibility and trial quality were assessed by the reviewer. Six trials were included. Routine tocolysis was associated with fewer failures of external cephalic version (relative risk 0.77, 95% confidence interval 0.64 to 0.92). There were no significant differences between non-cephalic presentations and caesarean sections. Fetal acoustic stimulation in midline fetal spine positions was associated with fewer failures of external cephalic version at term (relative risk 0.17, 95% confidence interval 0.05 to 0.60). No randomised trials of epidural analgesia or transabdominal amnioinfusion for external cephalic version at term were located. Routine tocolysis appears to reduce the failure rate of external cephalic version at term. Although promising, there is not enough evidence to evaluate the use of fetal acoustic stimulation in midline fetal spine positions. There is not enough evidence to evaluate the use of epidural analgesia or transabdominal amnioinfusion for external cephalic version at term.

Tocopherol inhibits the relaxing effect of terbutaline in the respiratory and reproductive tracts of the rat: the role of the oxidative stress index.

PubMed

Hódi, A; Földesi, I; Ducza, E; Hajagos-Tóth, J; Seres, A B; Klukovits, A; Gáspár, R

2014-06-06

Reactive oxygen species play a role in the signal transduction of beta-adrenergic receptors. We investigated whether an antioxidant (tocopherol) can reduce the effect of terbutaline in beta-2-adrenergic receptor (β2-AR)-regulated smooth muscles. Contractility of the tissues from nonpregnant (trachea) and 22-day-pregnant (myometrium and cervix) rats was investigated in an isolated organ bath. The tracheal and uterine β2-AR expressions were increased by 17-beta-estradiol valerate (E2) and progesterone (P4), respectively. The accumulation of cyclic-AMP (cAMP), and the total oxidant (TOS) and total antioxidant status (TAS) were also measured. The oxidative stress index (OSI) was defined as the ratio of TOS and TAS. Terbutaline (10(-10)-10(-5)M) decreased the contractions in the nontreated and the P4-pretreated myometria, but tocopherol (10(-7)M) did not alter these actions. Terbutaline (10(-6)M) increased the cervical resistance both in the nontreated and in the P4-treated samples, while tocopherol reduced this action only in the P4-treated cervices. Terbutaline (10(-9)-10(-4)M) reduced the tracheal tones both in the nontreated and in the E2-treated tissues, while tocopherol reduced these effects. The changes in the intracellular cAMP levels of the tissues were in harmony with the isolated organ results. The OSI was highest in the trachea and lowest in the pregnant myometrium. A higher OSI is linked to a higher tocopherol sensitivity of beta-mimetic-induced relaxation. Our results suggest that the antiasthmatic effect of beta-mimetics may worsen, while their tocolytic effect may remain unchanged during parallel tocopherol administration. Copyright © 2014 Elsevier Inc. All rights reserved.

Lessons learned from a single institution's retrospective analysis of emergent cesarean delivery following external cephalic version with and without neuraxial anesthesia.

PubMed

Ainsworth, A; Sviggum, H P; Tolcher, M C; Weaver, A L; Holman, M A; Arendt, K W

2017-05-01

To evaluate the risk of emergent cesarean delivery with the use of neuraxial anesthesia for external cephalic version in a single practice. Randomized trials have shown increased external cephalic version success when neuraxial anesthesia is used, without additional risk. We hypothesized that in our actual clinical practice, outside the confines of randomized trials, neuraxial anesthesia could be associated with an increased risk of emergent cesarean delivery. This retrospective cohort study included all women who underwent external cephalic version at a single institution with and without neuraxial anesthesia. The primary outcome was the incidence of emergent cesarean delivery (defined as delivery within 4hours of version). Secondary outcomes were version success and ultimate mode of delivery. A total of 135 women underwent external cephalic version procedures; 58 with neuraxial anesthesia (43.0%) and 77 without (57.0%). Location of the procedure, tocolytic therapy, and gestational age were different between groups. An increased rate of emergent cesarean delivery was found in procedures with neuraxial anesthesia compared to procedures without (5/58 (8.6%) compared to 0/77 (0.0%); 95% CI for difference, 1.4 to 15.8%; P=0.013). In this single hospital's practice, patients who may be at higher risk of complications and have a lesser likelihood of success were provided NA for ECV. As a result, the use of neuraxial anesthesia for external cephalic version was associated with a higher rate of emergent cesarean delivery. Obstetric and anesthetic practices should evaluate their patient selection and procedure protocol for external cephalic version under neuraxial anesthesia. Copyright © 2017 Elsevier Ltd. All rights reserved.

Tocolysis for repeat external cephalic version in breech presentation at term: a randomised, double-blinded, placebo-controlled trial.

PubMed

Impey, Lawrence; Pandit, Meghana

2005-05-01

External cephalic version (ECV) reduces the incidence of breech presentation at term and caesarean section for non-cephalic births. Tocolytics may improve success rates, but are time consuming, may cause side effects and have not been proven to alter caesarean section rates. The aim of this trial was to determine whether tocolysis should be used if ECV is being re-attempted after a failed attempt. To determine whether tocolysis should be used if ECV is being re-attempted after a failed attempt. Randomised, double-blinded, placebo-controlled trial. UK teaching hospital. One hundred and twenty-four women with a breech presentation at term who had undergone an unsuccessful attempt at ECV. Relative risks with 95% confidence intervals for categorical variables and a t test for continuous variables. Analysis was by intention to treat. Incidence of cephalic presentation at delivery. Secondary outcomes were caesarean section and measures of neonatal and maternal morbidity. The use of tocolysis for a repeat attempt at ECV significantly increases the incidence of cephalic presentation at delivery (RR 3.21; 95% CI 1.23-8.39) and reduces the incidence of caesarean section (RR 0.33; 95% CI 0.14-0.80). The effects were most marked in multiparous women (RR for cephalic presentation at delivery 9.38; 95% CI 1.64-53.62). Maternal and neonatal morbidity remain unchanged. The use of tocolysis increases the success rate of repeat ECV and reduces the incidence of caesarean section. A policy of only using tocolysis where an initial attempt has failed leads to a relatively high success rate with minimum usage of tocolysis.

Evaluating the Teratogenicity of Ritodrine and Nifedipine using a Frog Embryo Teratogenesis assay (FETAX).

PubMed

Boğa Pekmezekmek, Ayper; Binokay, Uğur Seçil; Seçilmiş, Mehmet Ata; Kumcu, Eda; Şimşek, Erhan; Akillioğlu, Kübra; Sertdemir, Yaşar; Özaykan, Besim

2015-01-01

The Frog Embryo Teratogenesis Assay-Xenopus (FETAX) was used to assess the teratogenic potential of two tocolytics. Embryos of the South African clawed frog, Xenopus laevis, were exposed to ritodrine or nifedipine. Exposure media were changed and monitored at 24-hour intervals. The 96-hour LC50 (Lethal concentration), the 96-hour EC50 (Malformation), and the No Observable Adverse Effect Concentrations (NOAEC) and the Lowest Observable Adverse Effect Concentration (LOAEC) for mortality, malformation and length were determined for each drug. Nifedipine was determined to be the more toxic and teratogenic than ritodrine, with a LC50 of 0.606 µg/L, an EC50 of 0.006 µg/L, and a teratogenicity Index (TI) value (LC50/EC50) of 101. On the other hand, the LC50 of ritodrine was 28.571 mg/L. In addition; the LC50, EC50 and TI values for nifedipine in the 5 mg/L ritodrine + nifedipine combination group were determined as 1.050 µg/L, 0.868 µg/L and 1.5 respectively. For ritodrine, the NOAEC and LOAEC values were determined as 2 mg/L and 4 mg/L, respectively. For the nifedipine and the ritodrine + nifedipine groups; while the LOAEC values of these groups were 0.0001 µg/L and 0.1 µg/L, respectively. NOAEC value couldn't be determined. Our results demonstrated that nifedipine administration was associated with higher levels of teratogenic and toxic effects. However, the ritodrine + nifedipine combination form reduced the toxic and teratogenic effects of nifedipine on Xenopus embryos. Further studies should be conducted in order to investigate the optimal combination concentrations of these substances for the treatment of preterm labor.

External cephalic version facilitation for breech presentation at term.

PubMed

Hofmeyr, G J

2001-01-01

Tocolytic drugs to relax the uterus as well as other methods have been also used in an attempt to facilitate external cephalic version at term. The objective of this review is to assess the effects of routine tocolysis, fetal acoustic stimulation, epidural or spinal analgesia and transabdominal amnioinfusion for external cephalic version at term on successful version and measures of pregnancy outcome. The Cochrane Pregnancy and Childbirth Group Trials Register and the Cochrane Controlled Trials Register were searched. Date of last search: April 2001. Randomised and quasi-randomised trials comparing routine versus selective tocolysis; fetal acoustic stimulation in midline fetal spine positions versus dummy or no stimulation; epidural or spinal analgesia versus no regional analgesia; or transabdominal amnioinfusion versus no amnioinfusion for external cephalic version at term. Eligibility and trial quality were assessed by the reviewer. In seven trials, routine tocolysis was associated with fewer failures of external cephalic version (relative risk 0.74, 95% confidence interval 0.64 to 0.87). There were no significant differences between non-cephalic presentations at birth. Caesarean sections were reduced (relative risk 0.85, confidence interval 0.72-0.99). Fetal acoustic stimulation in midline fetal spine positions was associated with fewer failures of external cephalic version at term (relative risk 0.17, 95% confidence interval 0.05 to 0.60). With epidural or spinal analgesia, external cephalic version failure, non-cephalic births and caesarean sections were reduced in one trial but not the other. The overall differences were not statistically significant. No randomised trials of transabdominal amnioinfusion for external cephalic version at term were located. Routine tocolysis appears to reduce the failure rate of external cephalic version at term. Although promising, there is not enough evidence to evaluate the use of fetal acoustic stimulation in midline fetal spine positions, nor of epidural or spinal analgesia. Large volume intravenous preloading may have contributed to the effectiveness demonstrated in one of the latter trials. No randomised trials of transabdominal amnioinfusion for external cephalic version at term were found.

Adjunctive clindamycin therapy for preterm labor: results of a double-blind, placebo-controlled trial.

PubMed

McGregor, J A; French, J I; Seo, K

1991-10-01

A double-blind, placebo-controlled, randomized trial was conducted to evaluate the efficacy, safety, and tolerance of a course of clindamycin (administered for 3 days intravenously and 4 days orally) among hospitalized women with preterm labor at less than or equal to 34 weeks' gestation who were treated with tocolytics. One hundred three woman-perinate pairs were analyzed. Univariate analysis demonstrated that pregnancies were continued longer in women treated with clindamycin than in women who received placebo (clindamycin-treated group, 35 days; placebo-treated group, 25 days; p = 0.02). Survival analysis showed that pregnancy continued at least 35.5 days in 50% of clindamycin-treated women versus 20 days for control women (p = 0.03). Obstetric and microbiologic parameters associated with treatment outcomes were also sought. Women with bacterial vaginosis more often delivered preterm (p = 0.03; relative risk, 1.4; 95% confidence interval, 1.04 to 2.0). Among women with bacterial vaginosis, trends for increased duration of pregnancy (clindamycin-treated group, 36 days; placebo-treated group, 19 days), increased birth weight (clindamycin-treated group, 2634 gm; placebo-treated group, 2256 gm), and increased mean gestational age at delivery (clindamycin-treated group, 35 weeks; placebo-treated group, 34 weeks) were associated with clindamycin treatment. Women with either group B streptococcus, Chlamydia trachomatis, Trichomonas vaginalis, or Staphylococcus aureus were more likely to have preterm premature rupture of membranes (p = 0.01). Clindamycin treatment of these women reduced the incidence of preterm premature rupture of membranes to that of uninfected subjects. Stratification by gestational age at enrollment showed clindamycin treatment to be associated with an increased interval to delivery only among mothers enrolled before 33 weeks' gestation (clindamycin-treated group, 40 days; placebo-treated group, 28 days; p less than 0.05). Treatment with clindamycin appeared safe and well tolerated, with benefits limited to women who were less than or equal to 32 weeks' gestation.

A New Slow Releasing, H2S Generating Compound, GYY4137 Relaxes Spontaneous and Oxytocin-Stimulated Contractions of Human and Rat Pregnant Myometrium

PubMed Central

Robinson, Hayley; Wray, Susan

2012-01-01

Better tocolytics are required to help prevent preterm labour. The gaseotransmitter Hydrogen sulphide (H2S) has been shown to reduce myometrial contractility and thus is of potential interest. However previous studies used NaHS, which is toxic and releases H2S as a non-physiological bolus and thus alternative H2S donors are sought. GYY4137 has been developed to slowly release H2S and hence better reflect endogenous physiological release. We have examined its effects on spontaneous and oxytocin-stimulated contractility and compared them to NaHS, in human and rat myometrium, throughout gestation. The effects on contractility in response to GYY4137 (1 nM–1 mM) and NaHS (1 mM) were examined on myometrial strips from, biopsies of women undergoing elective caesarean section or hysterectomy, and from non-pregnant, 14, 18, 22 day (term) gestation or labouring rats. In pregnant rat and human myometrium dose-dependent and significant decreases in spontaneous contractions were seen with increasing concentrations of GYY4137, which also reduced underlying Ca transients. GYY4137 and NaHS significantly reduced oxytocin-stimulated and high-K depolarised contractions as well as spontaneous activity. Their inhibitory effects increased as gestation advanced, but were abruptly reversed in labour. Glibenclamide, an inhibitor of ATP-sensitive potassium (KATP) channels, abolished the inhibitory effect of GYY4137. These data suggest (i) H2S contributes to uterine quiescence from mid-gestation until labor, (ii) that H2S affects L-type calcium channels and KATP channels reducing Ca entry and thereby myometrial contractions, (iii) add to the evidence that H2S plays a physiological role in relaxing myometrium, and thus (iv) H2S is an attractive target for therapeutic manipulation of human myometrial contractility. PMID:23029460

Vaginal progesterone as maintenance treatment after an episode of preterm labour (PROMISE) study: a multicentre, double-blind, randomised, placebo-controlled trial.

PubMed

Palacio, M; Cobo, T; Antolín, E; Ramirez, M; Cabrera, F; Mozo de Rosales, F; Bartha, J L; Juan, M; Martí, A; Oros, D; Rodríguez, À; Scazzocchio, E; Olivares, J M; Varea, S; Ríos, J; Gratacós, E

2016-11-01

To evaluate whether maintenance treatment with vaginal progesterone after an arrested preterm labour reduces the incidence of preterm delivery. Multicentre, randomised, double-blind, placebo-controlled trial. Twelve tertiary care centres in Spain. A total of 265 women with singleton pregnancy, preterm labour successfully arrested with tocolytic treatment, and cervical length of <25 mm. Randomisation was stratified by gestational age (from 24.0 to <31.0 weeks of gestation and from 31.0 to <34.0 weeks of gestation) and centre. Patients were randomly assigned, in a 1 : 1 ratio, to either daily vaginal capsules of 200 mg progesterone or placebo until delivery or 36.6 weeks of gestation, whichever occurred first. Primary outcome was delivery before 34.0 and 37.0 weeks of gestation. Secondary outcomes were discharge-to-delivery time, readmissions because of preterm labour, emergency service use, and neonatal morbidity and mortality. From June 2008 through June 2012, 1419 women were screened: 472 met the inclusion criteria and 265 were randomised. The final analysis included 258 women: 126 in the progesterone group and 132 in the placebo group. There were no significant differences between the progesterone and placebo groups in terms of delivery at <34 weeks of gestation [9/126 (7.1%) versus 10/132 (7.6%), P = 0.91] or <37 weeks of gestation [36/126 (28.6%) versus 29/132 (22.0%), P = 0.22]. There were no differences observed between groups when considering the two strata of gestational age at inclusion. A maintenance treatment of 200 mg of daily vaginal progesterone capsules in women discharged home after an episode of arrested preterm labour did not significantly reduce the rate of preterm delivery. Maintenance progesterone in 258 women after arrested PTL showed no benefit. © 2016 Royal College of Obstetricians and Gynaecologists.

Preliminary report of 48-hours Atosiban administration in spontaneous preterm labor - Doppler blood flow assessment of placental and fetal circulation.

PubMed

Grzesiak, Mariusz; Wilczynski, Jan

2013-01-01

The aims were to investigate whether there are any changes in placental and fetal circulation during Atosiban tocolysis within the first 48 hours of therapy. Detailed Doppler evaluation of placental and fetal circulation was performed prior to Atosiban administration and thereafter at 24 and 48 hours. Maternal heart rate and the pulsatility index (PI) in both uterine arteries (R-UtA, L-UtA) were assessed. Fetal heart rate (FHR), the resistance (RI) and pulsatility index (PI) of umbilical (UA) and middle cerebral artery (MCA) were measured. Additionally cerebroplacental ratio was calculated. E-wave/A-wave ratio (E/A) for atrioventricular valves, the myocardial performance index (MPI) and shortening fraction (SF) for both ventricles were calculated for both ventricles independently. To determine changes over time in all study variables analysis of variance (ANOVA) for repeated measurements followed by Tukey-Kramer's post hoc test was used. The effects of additional clinical covariates were checked. Maternal heart rate and blood flow in (R-UtA/L-UtA) were not altered significantly during Atosiban administration. No significant changes in FHR as well as Doppler parameters (RI, PI, PSV) in UA and MCA were recorded after 24/48 hours of tocolytic treatment. The mean values of cerebroplacental ratio (CPR) remained unaltered during treatment. Detailed evaluation of fetal cardiac function parameters (E/A, SF, MPI) calculated independently for both ventricles, revealed no significant changes over the time. To our best knowledge this study has been first evaluation of placental and fetal circulation with assessment of cardiac hemodynamic function during 48-hours administration of Atosiban. This kind of tocolysis treatment seems not to alter uterine nor fetal arterial blood flow pattern seriously. Hemodynamic cardiac activity in fetuses has remained unaffected. We cannot conclude definitely that there are absolutely no changes in the fetal hemodynamic condition due to Atosiban. Further studies should be performed to verify its possible influence on fetal venous blood flow.

Magnesium sulfate differentially modulates fetal membrane inflammation in a time-dependent manner.

PubMed

Cross, Sarah N; Nelson, Rachel A; Potter, Julie A; Norwitz, Errol R; Abrahams, Vikki M

2018-04-30

Chorioamnionitis and infection-associated inflammation are major causes of preterm birth. Magnesium sulfate (MgSO 4 ) is widely used in obstetrics as a tocolytic; however, its mechanism of action is unclear. This study sought to investigate how MgSO 4 modulates infection-associated inflammation in fetal membranes (FMs), and whether the response was time dependent. Human FM explants were treated with or without bacterial lipopolysaccharide (LPS); with or without MgSO 4 added either: 1 hour before LPS; at the same time as LPS; 1 hour post-LPS; or 2 hours post-LPS. Explants were also treated with or without viral dsRNA and LPS, alone or in combination; and MgSO 4 added 1 hour post-LPS After 24 hours, supernatants were measured for cytokines/chemokines; and tissue lysates measured for caspase-1 activity. Lipopolysaccharide-induced FM inflammation by upregulating the secretion of a number of inflammatory cytokines/chemokines. Magnesium sulfate administered 1-hour post-LPS inhibited FM secretion of IL-1β, IL-6, G-CSF, RANTES, and TNFα. Magnesium sulfate administered 2 hours post-LPS augmented FM secretion of these factors as well as IL-8, IFNγ, VEGF, GROα and IP-10. Magnesium sulfate delivered 1- hour post-LPS inhibited LPS-induced caspase-1 activity, and inhibited the augmented IL-1β response triggered by combination viral dsRNA and LPS. Magnesium sulfate differentially modulates LPS-induced FM inflammation in a time-dependent manner, in part through its modulation of caspase-1 activity. Thus, the timing of MgSO 4 administration may be critical in optimizing its anti-inflammatory effects in the clinical setting. MgSO 4 might also be useful at preventing FM inflammation triggered by a polymicrobial viral-bacterial infection. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

40 CFR 300.910 - Authorization of use.

Code of Federal Regulations, 2012 CFR

2012-07-01

... dispersants, surface washing agents, surface collecting agents, bioremediation agents, or miscellaneous oil... agents, surface collecting agents, bioremediation agents, or miscellaneous oil spill control agents on..., bioremediation agent, or miscellaneous oil spill control agent, including products not listed on the NCP Product...

40 CFR 300.910 - Authorization of use.

Code of Federal Regulations, 2013 CFR

2013-07-01

... dispersants, surface washing agents, surface collecting agents, bioremediation agents, or miscellaneous oil... agents, surface collecting agents, bioremediation agents, or miscellaneous oil spill control agents on..., bioremediation agent, or miscellaneous oil spill control agent, including products not listed on the NCP Product...

40 CFR 300.910 - Authorization of use.

Code of Federal Regulations, 2014 CFR

2014-07-01

... dispersants, surface washing agents, surface collecting agents, bioremediation agents, or miscellaneous oil... agents, surface collecting agents, bioremediation agents, or miscellaneous oil spill control agents on..., bioremediation agent, or miscellaneous oil spill control agent, including products not listed on the NCP Product...

40 CFR 300.910 - Authorization of use.

Code of Federal Regulations, 2010 CFR

2010-07-01

... dispersants, surface washing agents, surface collecting agents, bioremediation agents, or miscellaneous oil... agents, surface collecting agents, bioremediation agents, or miscellaneous oil spill control agents on..., bioremediation agent, or miscellaneous oil spill control agent, including products not listed on the NCP Product...

78 FR 22256 - Proposed Information Collection Request; Comment Request; The National Oil and Hazardous...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-04-15

... Chemicals''). The use of bioremediation agents, dispersants, surface washing agents, surface collecting... basic categories: dispersants, surface washing agents, surface collecting agents, bioremediation agents..., manufacturers of bioremediation agents, dispersants, surface collecting agents, surface washing agents...

Emergency management of chemical weapons injuries.

PubMed

Anderson, Peter D

2012-02-01

The potential for chemical weapons to be used in terrorism is a real possibility. Classes of chemical weapons include nerve agents, vesicants (blister agents), choking agents, incapacitating agents, riot control agents, blood agents, and toxic industrial chemicals. The nerve agents work by blocking the actions of acetylcholinesterase leading to a cholinergic syndrome. Nerve agents include sarin, tabun, VX, cyclosarin, and soman. The vesicants include sulfur mustard and lewisite. The vesicants produce blisters and also damage the upper airways. Choking agents include phosgene and chlorine gas. Choking agents cause pulmonary edema. Incapacitating agents include fentanyl and its derivatives and adamsite. Riot control agents include Mace and pepper spray. Blood agents include cyanide. The mechanism of toxicity for cyanide is blocking oxidative phosphorylation. Toxic industrial chemicals include agents such as formaldehyde, hydrofluoric acid, and ammonia.

40 CFR 300.920 - Addition of products to Schedule.

Code of Federal Regulations, 2011 CFR

2011-07-01

... manufacturer of his decision in writing. (b) Surface washing agents, surface collecting agents, bioremediation... collecting agent, bioremediation agent, or miscellaneous oil spill control agent to the NCP Product Schedule... collecting agent, bioremediation agent, or miscellaneous oil spill control agent. On the basis of this data...

40 CFR 300.920 - Addition of products to Schedule.

Code of Federal Regulations, 2014 CFR

2014-07-01

... manufacturer of his decision in writing. (b) Surface washing agents, surface collecting agents, bioremediation... collecting agent, bioremediation agent, or miscellaneous oil spill control agent to the NCP Product Schedule... collecting agent, bioremediation agent, or miscellaneous oil spill control agent. On the basis of this data...

40 CFR 300.920 - Addition of products to Schedule.

Code of Federal Regulations, 2012 CFR

2012-07-01

... manufacturer of his decision in writing. (b) Surface washing agents, surface collecting agents, bioremediation... collecting agent, bioremediation agent, or miscellaneous oil spill control agent to the NCP Product Schedule... collecting agent, bioremediation agent, or miscellaneous oil spill control agent. On the basis of this data...

40 CFR 300.920 - Addition of products to Schedule.

Code of Federal Regulations, 2013 CFR

2013-07-01

... manufacturer of his decision in writing. (b) Surface washing agents, surface collecting agents, bioremediation... collecting agent, bioremediation agent, or miscellaneous oil spill control agent to the NCP Product Schedule... collecting agent, bioremediation agent, or miscellaneous oil spill control agent. On the basis of this data...

40 CFR 300.920 - Addition of products to Schedule.

Code of Federal Regulations, 2010 CFR

2010-07-01

... manufacturer of his decision in writing. (b) Surface washing agents, surface collecting agents, bioremediation... collecting agent, bioremediation agent, or miscellaneous oil spill control agent to the NCP Product Schedule... collecting agent, bioremediation agent, or miscellaneous oil spill control agent. On the basis of this data...

Interventions to help external cephalic version for breech presentation at term.

PubMed

Hofmeyr, G J

2002-01-01

Breech presentation places a fetus at increased risk. The outcome for the baby is improved by planned caesarean section compared with planned vaginal delivery. External cephalic version attempt reduces the chance of breech presentation at birth, but is not always successful. Tocolytic drugs to relax the uterus as well as other methods have been also used in an attempt to facilitate external cephalic version at term. The objective of this review is to assess the effects of routine tocolysis, fetal acoustic stimulation, epidural or spinal analgesia and transabdominal amnioinfusion for external cephalic version at term on successful version and measures of pregnancy outcome. The Cochrane Pregnancy and Childbirth Group Trials Register (searched December 2001) and the Cochrane Controlled Trials Register (The Cochrane Library, Issue 4, 2001) were searched. Randomised and quasi-randomised trials comparing routine versus selective or no tocolysis; fetal acoustic stimulation in midline fetal spine positions versus dummy or no stimulation; epidural or spinal analgesia versus no regional analgesia; or transabdominal amnioinfusion versus no amnioinfusion for external cephalic version at term. Eligibility and trial quality were assessed by the reviewer. In six trials, routine tocolysis was associated with fewer failures of external cephalic version (relative risk 0.74, 95% confidence interval 0.64 to 0.87). The reduction in non-cephalic presentations at birth was not statistically significant. Caesarean sections were reduced (relative risk 0.85, 95% confidence interval 0.72 to 0.99). Fetal acoustic stimulation in midline fetal spine positions was associated with fewer failures of external cephalic version at term (relative risk 0.17, 95% confidence interval 0.05 to 0.60). With epidural or spinal analgesia, external cephalic version failure, non-cephalic births and caesarean sections were reduced in two trials but not the other. The overall differences were not statistically significant. No randomised trials of transabdominal amnioinfusion for external cephalic version at term were located. Routine tocolysis appears to reduce the failure rate of external cephalic version at term. Although promising, there is not enough evidence to evaluate the use of fetal acoustic stimulation in midline fetal spine positions, nor of epidural or spinal analgesia. Large volume intravenous preloading may have contributed to the effectiveness demonstrated in two of the latter trials. No randomised trials of transabdominal amnioinfusion for external cephalic version at term were found.

Androgens in pregnancy: roles in parturition

PubMed Central

Makieva, Sofia; Saunders, Philippa T.K.; Norman, Jane E.

2014-01-01

BACKGROUND Understanding the physiology of pregnancy enables effective management of pregnancy complications that could otherwise be life threatening for both mother and fetus. A functional uterus (i) retains the fetus in utero during pregnancy without initiating stretch-induced contractions and (ii) is able to dilate the cervix and contract the myometrium at term to deliver the fetus. The onset of labour is associated with successful cervical remodelling and contraction of myometrium, arising from concomitant activation of uterine immune and endocrine systems. A large body of evidence suggests that actions of local steroid hormones may drive changes occurring in the uterine microenvironment at term. Although there have been a number of studies considering the potential role(s) played by progesterone and estrogen at the time of parturition, the bio-availability and effects of androgens during pregnancy have received less scrutiny. The aim of this review is to highlight potential roles of androgens in the biology of pregnancy and parturition. METHODS A review of published literature was performed to address (i) androgen concentrations, including biosynthesis and clearance, in maternal and fetal compartments throughout gestation, (ii) associations of androgen concentrations with adverse pregnancy outcomes, (iii) the role of androgens in the physiology of cervical remodelling and finally (iv) the role of androgens in the physiology of myometrial function including any impact on contractility. RESULTS Some, but not all, androgens increase throughout gestation in maternal circulation. The effects of this increase are not fully understood; however, evidence suggests that increased androgens might regulate key processes during pregnancy and parturition. For example, androgens are believed to be critical for cervical remodelling at term, in particular cervical ripening, via regulation of cervical collagen fibril organization. Additionally, a number of studies highlight potential roles for androgens in myometrial relaxation via non-genomic, AR-independent pathways critical for the pregnancy reaching term. Understanding of the molecular events leading to myometrial relaxation is an important step towards development of novel targeted tocolytic drugs. CONCLUSIONS The increase in androgen levels throughout gestation is likely to be important for establishment and maintenance of pregnancy and initiation of parturition. Further investigation of the underlying mechanisms of androgen action on cervical remodelling and myometrial contractility is needed. The insights gained may facilitate the development of new therapeutic approaches to manage pregnancy complications such as preterm birth. PMID:24643344

Two types of health care systems and their influence on the introduction of perinatal care: an epidemiological twin model in Berlin from 1950 to 1990.

PubMed

Arabin, B; Raum, E; Mohnhaupt, A; Schwartz, F W

1999-06-01

When perinatal medicine emerged as a new medical discipline in the 1960s, Berlin was as one of the world's leading centers. During that time, the city was separated into two parts, each fostering its own health care system. After the destruction of the Berlin Wall, it was possible to speak with the citizens of East Berlin and to access their database systems. This created the singular opportunity to objectively compare the development of perinatal care in both parts of Berlin. Rates of maternal, perinatal, and infant mortality as well as the rate of preterm deliveries were evaluated over time and between East and West Berlin. The timing of introduction of 20 specific perinatal interventions was evaluated across 18 hospitals with more than 500 deliveries (11 in West Berlin and 7 in East Berlin). Interviews were conducted with 100 gynecologists, 100 midwives, and 100 women who had recently delivered their first child from each side of the city regarding their opinions of the importance of these interventions for the quality of perinatal medicine and how they would distribute a budget to improve maternity care. Maternal, perinatal, and infant mortality decreased in both parts of Berlin until 1990 (p < 0.0001), without significant differences between East and West Berlin, though the preterm delivery rate was slightly lower in East Berlin compared with West Berlin (p < 0.06). Some new clinical techniques and treatments--such as cardiotocography, ultrasound, tocolytic therapy, and peridural anesthesia--were introduced earlier in West Berlin. In contrast, certain public health measures--such as maternal transport, screening programs for diabetes, and support of breastfeeding--were introduced much earlier in East Berlin. There were significant differences between the beliefs of gynecologists, midwives, and mothers in East and West Berlin. In general, citizens of East Berlin were more enthusiastic about technological medical advances, whereas citizens of West Berlin were more supportive of public health and alternative methods. In addition, there were significant differences between female and male physicians in their beliefs about how to improve health care, regardless of whether they resided in East or West Berlin. The results of this study may serve as a basis for reflection on how different social circumstances and health care policies can influence the improvement of maternal and child health care.

Nifedipine versus atosiban for threatened preterm birth (APOSTEL III): a multicentre, randomised controlled trial.

PubMed

van Vliet, Elvira O G; Nijman, Tobias A J; Schuit, Ewoud; Heida, Karst Y; Opmeer, Brent C; Kok, Marjolein; Gyselaers, Wilfried; Porath, Martina M; Woiski, Mallory; Bax, Caroline J; Bloemenkamp, Kitty W M; Scheepers, Hubertina C J; Jacquemyn, Yves; Beek, Erik van; Duvekot, Johannes J; Franssen, Maureen T M; Papatsonis, Dimitri N; Kok, Joke H; van der Post, Joris A M; Franx, Arie; Mol, Ben W; Oudijk, Martijn A

2016-05-21

In women with threatened preterm birth, delay of delivery by 48 h allows antenatal corticosteroids to improve neonatal outcomes. For this reason, tocolytics are often administered for 48 h; however, there is no consensus about which drug results in the best maternal and neonatal outcomes. In the APOSTEL III trial we aimed to compare the effectiveness and safety of the calcium-channel blocker nifedipine and the oxytocin inhibitor atosiban in women with threatened preterm birth. We did this multicentre, randomised controlled trial in ten tertiary and nine teaching hospitals in the Netherlands and Belgium. Women with threatened preterm birth (gestational age 25-34 weeks) were randomly assigned (1:1) to either oral nifedipine or intravenous atosiban for 48 h. An independent data manager used a web-based computerised programme to randomly assign women in permuted block sizes of four, with groups stratified by centre. Clinicians, outcome assessors, and women were not masked to treatment group. The primary outcome was a composite of adverse perinatal outcomes, which included perinatal mortality, bronchopulmonary dysplasia, sepsis, intraventricular haemorrhage, periventricular leukomalacia, and necrotising enterocolitis. Analysis was done in all women and babies with follow-up data. The study is registered at the Dutch Clinical Trial Registry, number NTR2947. Between July 6, 2011, and July 7, 2014, we randomly assigned 254 women to nifedipine and 256 to atosiban. Primary outcome data were available for 248 women and 297 babies in the nifedipine group and 255 women and 294 babies in the atosiban group. The primary outcome occurred in 42 babies (14%) in the nifedipine group and in 45 (15%) in the atosiban group (relative risk [RR] 0·91, 95% CI 0·61-1·37). 16 (5%) babies died in the nifedipine group and seven (2%) died in the atosiban group (RR 2·20, 95% CI 0·91-5·33); all deaths were deemed unlikely to be related to the study drug. Maternal adverse events did not differ between groups. In women with threatened preterm birth, 48 h of tocolysis with nifedipine or atosiban results in similar perinatal outcomes. Future clinical research should focus on large placebo-controlled trials, powered for perinatal outcomes. ZonMw (the Netherlands Organisation for Health Research and Development). Copyright © 2016 Elsevier Ltd. All rights reserved.

Androgens in pregnancy: roles in parturition.

PubMed

Makieva, Sofia; Saunders, Philippa T K; Norman, Jane E

2014-01-01

Understanding the physiology of pregnancy enables effective management of pregnancy complications that could otherwise be life threatening for both mother and fetus. A functional uterus (i) retains the fetus in utero during pregnancy without initiating stretch-induced contractions and (ii) is able to dilate the cervix and contract the myometrium at term to deliver the fetus. The onset of labour is associated with successful cervical remodelling and contraction of myometrium, arising from concomitant activation of uterine immune and endocrine systems. A large body of evidence suggests that actions of local steroid hormones may drive changes occurring in the uterine microenvironment at term. Although there have been a number of studies considering the potential role(s) played by progesterone and estrogen at the time of parturition, the bio-availability and effects of androgens during pregnancy have received less scrutiny. The aim of this review is to highlight potential roles of androgens in the biology of pregnancy and parturition. A review of published literature was performed to address (i) androgen concentrations, including biosynthesis and clearance, in maternal and fetal compartments throughout gestation, (ii) associations of androgen concentrations with adverse pregnancy outcomes, (iii) the role of androgens in the physiology of cervical remodelling and finally (iv) the role of androgens in the physiology of myometrial function including any impact on contractility. Some, but not all, androgens increase throughout gestation in maternal circulation. The effects of this increase are not fully understood; however, evidence suggests that increased androgens might regulate key processes during pregnancy and parturition. For example, androgens are believed to be critical for cervical remodelling at term, in particular cervical ripening, via regulation of cervical collagen fibril organization. Additionally, a number of studies highlight potential roles for androgens in myometrial relaxation via non-genomic, AR-independent pathways critical for the pregnancy reaching term. Understanding of the molecular events leading to myometrial relaxation is an important step towards development of novel targeted tocolytic drugs. The increase in androgen levels throughout gestation is likely to be important for establishment and maintenance of pregnancy and initiation of parturition. Further investigation of the underlying mechanisms of androgen action on cervical remodelling and myometrial contractility is needed. The insights gained may facilitate the development of new therapeutic approaches to manage pregnancy complications such as preterm birth. © The Author 2014. Published by Oxford University Press on behalf of the European Society of Human Reproduction and Embryology.

Double agents and secret agents: the emerging fields of exogenous chemical exchange saturation transfer and T2-exchange magnetic resonance imaging contrast agents for molecular imaging.

PubMed

Daryaei, Iman; Pagel, Mark D

2015-01-01

Two relatively new types of exogenous magnetic resonance imaging contrast agents may provide greater impact for molecular imaging by providing greater specificity for detecting molecular imaging biomarkers. Exogenous chemical exchange saturation transfer (CEST) agents rely on the selective saturation of the magnetization of a proton on an agent, followed by chemical exchange of a proton from the agent to water. The selective detection of a biomarker-responsive CEST signal and an unresponsive CEST signal, followed by the ratiometric comparison of these signals, can improve biomarker specificity. We refer to this improvement as a "double-agent" approach to molecular imaging. Exogenous T 2 -exchange agents also rely on chemical exchange of protons between the agent and water, especially with an intermediate rate that lies between the slow exchange rates of CEST agents and the fast exchange rates of traditional T 1 and T 2 agents. Because of this intermediate exchange rate, these agents have been relatively unknown and have acted as "secret agents" in the contrast agent research field. This review exposes these secret agents and describes the merits of double agents through examples of exogenous agents that detect enzyme activity, nucleic acids and gene expression, metabolites, ions, redox state, temperature, and pH. Future directions are also provided for improving both types of contrast agents for improved molecular imaging and clinical translation. Therefore, this review provides an overview of two new types of exogenous contrast agents that are becoming useful tools within the armamentarium of molecular imaging.

Petri Nets as Modeling Tool for Emergent Agents

NASA Technical Reports Server (NTRS)

Bergman, Marto

2004-01-01

Emergent agents, those agents whose local interactions can cause unexpected global results, require a method of modeling that is both dynamic and structured Petri Nets, a modeling tool developed for dynamic discrete event system of mainly functional agents, provide this, and have the benefit of being an established tool. We present here the details of the modeling method here and discuss how to implement its use for modeling agent-based systems. Petri Nets have been used extensively in the modeling of functional agents, those agents who have defined purposes and whose actions should result in a know outcome. However, emergent agents, those agents who have a defined structure but whose interaction causes outcomes that are unpredictable, have not yet found a modeling style that suits them. A problem with formally modeling emergent agents that any formal modeling style usually expects to show the results of a problem and the results of problems studied using emergent agents are not apparent from the initial construction. However, the study of emergent agents still requires a method to analyze the agents themselves, and have sensible conversation about the differences and similarities between types of emergent agents. We attempt to correct this problem by applying Petri Nets to the characterization of emergent agents. In doing so, the emergent properties of these agents can be highlighted, and conversation about the nature and compatibility of the differing methods of agent creation can begin.

Clustering recommendations to compute agent reputation

NASA Astrophysics Data System (ADS)

Bedi, Punam; Kaur, Harmeet

2005-03-01

Traditional centralized approaches to security are difficult to apply to multi-agent systems which are used nowadays in e-commerce applications. Developing a notion of trust that is based on the reputation of an agent can provide a softer notion of security that is sufficient for many multi-agent applications. Our paper proposes a mechanism for computing reputation of the trustee agent for use by the trustier agent. The trustier agent computes the reputation based on its own experience as well as the experience the peer agents have with the trustee agents. The trustier agents intentionally interact with the peer agents to get their experience information in the form of recommendations. We have also considered the case of unintentional encounters between the referee agents and the trustee agent, which can be directly between them or indirectly through a set of interacting agents. The clustering is done to filter off the noise in the recommendations in the form of outliers. The trustier agent clusters the recommendations received from referee agents on the basis of the distances between recommendations using the hierarchical agglomerative method. The dendogram hence obtained is cut at the required similarity level which restricts the maximum distance between any two recommendations within a cluster. The cluster with maximum number of elements denotes the views of the majority of recommenders. The center of this cluster represents the reputation of the trustee agent which can be computed using c-means algorithm.

Forest Service special agents, assistant special agents in charge, senior special agents, and supervisory special agents report: nationwide study

Treesearch

Deborah J. Chavez; Joanne F. Tynon

2007-01-01

This is the fourth in a series of studies to evaluate perceptions of U.S. Department of Agriculture Forest Service law enforcement personnel of the roles, responsibilities, and issues related to their jobs. An e-mail survey was administered to the 89 Forest Service special agents, assistant special agents in charge, senior special agents, and supervisory special agents...

Chemical warfare agents.

PubMed

Kuca, Kamil; Pohanka, Miroslav

2010-01-01

Chemical warfare agents are compounds of different chemical structures. Simple molecules such as chlorine as well as complex structures such as ricin belong to this group. Nerve agents, vesicants, incapacitating agents, blood agents, lung-damaging agents, riot-control agents and several toxins are among chemical warfare agents. Although the use of these compounds is strictly prohibited, the possible misuse by terrorist groups is a reality nowadays. Owing to this fact, knowledge of the basic properties of these substances is of a high importance. This chapter briefly introduces the separate groups of chemical warfare agents together with their members and the potential therapy that should be applied in case someone is intoxicated by these agents.

Advances in Magnetic Resonance Imaging Contrast Agents for Biomarker Detection

PubMed Central

Sinharay, Sanhita; Pagel, Mark D.

2016-01-01

Recent advances in magnetic resonance imaging (MRI) contrast agents have provided new capabilities for biomarker detection through molecular imaging. MRI contrast agents based on the T2 exchange mechanism have more recently expanded the armamentarium of agents for molecular imaging. Compared with T1 and T2* agents, T2 exchange agents have a slower chemical exchange rate, which improves the ability to design these MRI contrast agents with greater specificity for detecting the intended biomarker. MRI contrast agents that are detected through chemical exchange saturation transfer (CEST) have even slower chemical exchange rates. Another emerging class of MRI contrast agents uses hyperpolarized 13C to detect the agent with outstanding sensitivity. These hyperpolarized 13C agents can be used to track metabolism and monitor characteristics of the tissue microenvironment. Together, these various MRI contrast agents provide excellent opportunities to develop molecular imaging for biomarker detection. PMID:27049630

Needs, Pains, and Motivations in Autonomous Agents.

PubMed

Starzyk, Janusz A; Graham, James; Puzio, Leszek

This paper presents the development of a motivated learning (ML) agent with symbolic I/O. Our earlier work on the ML agent was enhanced, giving it autonomy for interaction with other agents. Specifically, we equipped the agent with drives and pains that establish its motivations to learn how to respond to desired and undesired events and create related abstract goals. The purpose of this paper is to explore the autonomous development of motivations and memory in agents within a simulated environment. The ML agent has been implemented in a virtual environment created within the NeoAxis game engine. Additionally, to illustrate the benefits of an ML-based agent, we compared the performance of our algorithm against various reinforcement learning (RL) algorithms in a dynamic test scenario, and demonstrated that our ML agent learns better than any of the tested RL agents.This paper presents the development of a motivated learning (ML) agent with symbolic I/O. Our earlier work on the ML agent was enhanced, giving it autonomy for interaction with other agents. Specifically, we equipped the agent with drives and pains that establish its motivations to learn how to respond to desired and undesired events and create related abstract goals. The purpose of this paper is to explore the autonomous development of motivations and memory in agents within a simulated environment. The ML agent has been implemented in a virtual environment created within the NeoAxis game engine. Additionally, to illustrate the benefits of an ML-based agent, we compared the performance of our algorithm against various reinforcement learning (RL) algorithms in a dynamic test scenario, and demonstrated that our ML agent learns better than any of the tested RL agents.

Double agents and secret agents: the emerging fields of exogenous chemical exchange saturation transfer and T2-exchange magnetic resonance imaging contrast agents for molecular imaging

PubMed Central

Daryaei, Iman; Pagel, Mark D

2016-01-01

Two relatively new types of exogenous magnetic resonance imaging contrast agents may provide greater impact for molecular imaging by providing greater specificity for detecting molecular imaging biomarkers. Exogenous chemical exchange saturation transfer (CEST) agents rely on the selective saturation of the magnetization of a proton on an agent, followed by chemical exchange of a proton from the agent to water. The selective detection of a biomarker-responsive CEST signal and an unresponsive CEST signal, followed by the ratiometric comparison of these signals, can improve biomarker specificity. We refer to this improvement as a “double-agent” approach to molecular imaging. Exogenous T2-exchange agents also rely on chemical exchange of protons between the agent and water, especially with an intermediate rate that lies between the slow exchange rates of CEST agents and the fast exchange rates of traditional T1 and T2 agents. Because of this intermediate exchange rate, these agents have been relatively unknown and have acted as “secret agents” in the contrast agent research field. This review exposes these secret agents and describes the merits of double agents through examples of exogenous agents that detect enzyme activity, nucleic acids and gene expression, metabolites, ions, redox state, temperature, and pH. Future directions are also provided for improving both types of contrast agents for improved molecular imaging and clinical translation. Therefore, this review provides an overview of two new types of exogenous contrast agents that are becoming useful tools within the armamentarium of molecular imaging. PMID:27747191

The New Agent: A Qualitative Study to Strategically Adapt New Agent Professional Development

ERIC Educational Resources Information Center

Baker, Lauri M.; Hadley, Gregg

2014-01-01

The qualitative study reported here assessed the needs of agents related to new agent professional development to improve the current model. Agents who participated in new agent professional development within the last 5 years were selected to participate in focus groups to determine concerns and continued needs. Agents enjoyed networking and…

Burnout among Extension Agents in the Ohio Cooperative Extension Service.

ERIC Educational Resources Information Center

Igodan, O. Chris; Newcomb, L. H.

A study examined the extent and causes of burnout among extension agents in Ohio. From the 241 extension agents working in the 88 counties of Ohio, researchers selected a random sample of 101 agents. Included in the sample were 34 agriculture agents, 33 home economics agents. Included in the sample agents were asked to complete a survey…

CATS-based Agents That Err

NASA Technical Reports Server (NTRS)

Callantine, Todd J.

2002-01-01

This report describes preliminary research on intelligent agents that make errors. Such agents are crucial to the development of novel agent-based techniques for assessing system safety. The agents extend an agent architecture derived from the Crew Activity Tracking System that has been used as the basis for air traffic controller agents. The report first reviews several error taxonomies. Next, it presents an overview of the air traffic controller agents, then details several mechanisms for causing the agents to err in realistic ways. The report presents a performance assessment of the error-generating agents, and identifies directions for further research. The research was supported by the System-Wide Accident Prevention element of the FAA/NASA Aviation Safety Program.

Resilient Distributed Estimation Through Adversary Detection

NASA Astrophysics Data System (ADS)

Chen, Yuan; Kar, Soummya; Moura, Jose M. F.

2018-05-01

This paper studies resilient multi-agent distributed estimation of an unknown vector parameter when a subset of the agents is adversarial. We present and analyze a Flag Raising Distributed Estimator ($\\mathcal{FRDE}$) that allows the agents under attack to perform accurate parameter estimation and detect the adversarial agents. The $\\mathcal{FRDE}$ algorithm is a consensus+innovations estimator in which agents combine estimates of neighboring agents (consensus) with local sensing information (innovations). We establish that, under $\\mathcal{FRDE}$, either the uncompromised agents' estimates are almost surely consistent or the uncompromised agents detect compromised agents if and only if the network of uncompromised agents is connected and globally observable. Numerical examples illustrate the performance of $\\mathcal{FRDE}$.

System for reactivating catalysts

DOEpatents

Ginosar, Daniel M.; Thompson, David N.; Anderson, Raymond P.

2010-03-02

A method of reactivating a catalyst, such as a solid catalyst or a liquid catalyst is provided. The method comprises providing a catalyst that is at least partially deactivated by fouling agents. The catalyst is contacted with a fluid reactivating agent that is at or above a critical point of the fluid reactivating agent and is of sufficient density to dissolve impurities. The fluid reactivating agent reacts with at least one fouling agent, releasing the at least one fouling agent from the catalyst. The at least one fouling agent becomes dissolved in the fluid reactivating agent and is subsequently separated or removed from the fluid reactivating agent so that the fluid reactivating agent may be reused. A system for reactivating a catalyst is also disclosed.

Design and Simulation of Material-Integrated Distributed Sensor Processing with a Code-Based Agent Platform and Mobile Multi-Agent Systems

PubMed Central

Bosse, Stefan

2015-01-01

Multi-agent systems (MAS) can be used for decentralized and self-organizing data processing in a distributed system, like a resource-constrained sensor network, enabling distributed information extraction, for example, based on pattern recognition and self-organization, by decomposing complex tasks in simpler cooperative agents. Reliable MAS-based data processing approaches can aid the material-integration of structural-monitoring applications, with agent processing platforms scaled to the microchip level. The agent behavior, based on a dynamic activity-transition graph (ATG) model, is implemented with program code storing the control and the data state of an agent, which is novel. The program code can be modified by the agent itself using code morphing techniques and is capable of migrating in the network between nodes. The program code is a self-contained unit (a container) and embeds the agent data, the initialization instructions and the ATG behavior implementation. The microchip agent processing platform used for the execution of the agent code is a standalone multi-core stack machine with a zero-operand instruction format, leading to a small-sized agent program code, low system complexity and high system performance. The agent processing is token-queue-based, similar to Petri-nets. The agent platform can be implemented in software, too, offering compatibility at the operational and code level, supporting agent processing in strong heterogeneous networks. In this work, the agent platform embedded in a large-scale distributed sensor network is simulated at the architectural level by using agent-based simulation techniques. PMID:25690550

Design and simulation of material-integrated distributed sensor processing with a code-based agent platform and mobile multi-agent systems.

PubMed

Bosse, Stefan

2015-02-16

Multi-agent systems (MAS) can be used for decentralized and self-organizing data processing in a distributed system, like a resource-constrained sensor network, enabling distributed information extraction, for example, based on pattern recognition and self-organization, by decomposing complex tasks in simpler cooperative agents. Reliable MAS-based data processing approaches can aid the material-integration of structural-monitoring applications, with agent processing platforms scaled to the microchip level. The agent behavior, based on a dynamic activity-transition graph (ATG) model, is implemented with program code storing the control and the data state of an agent, which is novel. The program code can be modified by the agent itself using code morphing techniques and is capable of migrating in the network between nodes. The program code is a self-contained unit (a container) and embeds the agent data, the initialization instructions and the ATG behavior implementation. The microchip agent processing platform used for the execution of the agent code is a standalone multi-core stack machine with a zero-operand instruction format, leading to a small-sized agent program code, low system complexity and high system performance. The agent processing is token-queue-based, similar to Petri-nets. The agent platform can be implemented in software, too, offering compatibility at the operational and code level, supporting agent processing in strong heterogeneous networks. In this work, the agent platform embedded in a large-scale distributed sensor network is simulated at the architectural level by using agent-based simulation techniques.

BSL-3 laboratory practices in the United States: comparison of select agent and non-select agent facilities.

PubMed

Richards, Stephanie L; Pompei, Victoria C; Anderson, Alice

2014-01-01

New construction of biosafety level 3 (BSL-3) laboratories in the United States has increased in the past decade to facilitate research on potential bioterrorism agents. The Centers for Disease Control and Prevention inspect BSL-3 facilities and review commissioning documentation, but no single agency has oversight over all BSL-3 facilities. This article explores the extent to which standard operating procedures in US BSL-3 facilities vary between laboratories with select agent or non-select agent status. Comparisons are made for the following variables: personnel training, decontamination, personal protective equipment (PPE), medical surveillance, security access, laboratory structure and maintenance, funding, and pest management. Facilities working with select agents had more complex training programs and decontamination procedures than non-select agent facilities. Personnel working in select agent laboratories were likely to use powered air purifying respirators, while non-select agent laboratories primarily used N95 respirators. More rigorous medical surveillance was carried out in select agent workers (although not required by the select agent program) and a higher level of restrictive access to laboratories was found. Most select agent and non-select agent laboratories reported adequate structural integrity in facilities; however, differences were observed in personnel perception of funding for repairs. Pest management was carried out by select agent personnel more frequently than non-select agent personnel. Our findings support the need to promote high quality biosafety training and standard operating procedures in both select agent and non-select agent laboratories to improve occupational health and safety.

BSL-3 Laboratory Practices in the United States: Comparison of Select Agent and Non–Select Agent Facilities

PubMed Central

Pompei, Victoria C.; Anderson, Alice

2014-01-01

New construction of biosafety level 3 (BSL-3) laboratories in the United States has increased in the past decade to facilitate research on potential bioterrorism agents. The Centers for Disease Control and Prevention inspect BSL-3 facilities and review commissioning documentation, but no single agency has oversight over all BSL-3 facilities. This article explores the extent to which standard operating procedures in US BSL-3 facilities vary between laboratories with select agent or non–select agent status. Comparisons are made for the following variables: personnel training, decontamination, personal protective equipment (PPE), medical surveillance, security access, laboratory structure and maintenance, funding, and pest management. Facilities working with select agents had more complex training programs and decontamination procedures than non–select agent facilities. Personnel working in select agent laboratories were likely to use powered air purifying respirators, while non–select agent laboratories primarily used N95 respirators. More rigorous medical surveillance was carried out in select agent workers (although not required by the select agent program) and a higher level of restrictive access to laboratories was found. Most select agent and non–select agent laboratories reported adequate structural integrity in facilities; however, differences were observed in personnel perception of funding for repairs. Pest management was carried out by select agent personnel more frequently than non–select agent personnel. Our findings support the need to promote high quality biosafety training and standard operating procedures in both select agent and non–select agent laboratories to improve occupational health and safety. PMID:24552359

Multi-Agent Patrolling under Uncertainty and Threats.

PubMed

Chen, Shaofei; Wu, Feng; Shen, Lincheng; Chen, Jing; Ramchurn, Sarvapali D

2015-01-01

We investigate a multi-agent patrolling problem where information is distributed alongside threats in environments with uncertainties. Specifically, the information and threat at each location are independently modelled as multi-state Markov chains, whose states are not observed until the location is visited by an agent. While agents will obtain information at a location, they may also suffer damage from the threat at that location. Therefore, the goal of the agents is to gather as much information as possible while mitigating the damage incurred. To address this challenge, we formulate the single-agent patrolling problem as a Partially Observable Markov Decision Process (POMDP) and propose a computationally efficient algorithm to solve this model. Building upon this, to compute patrols for multiple agents, the single-agent algorithm is extended for each agent with the aim of maximising its marginal contribution to the team. We empirically evaluate our algorithm on problems of multi-agent patrolling and show that it outperforms a baseline algorithm up to 44% for 10 agents and by 21% for 15 agents in large domains.

Prediction, events, and the advantage of agents: the processing of semantic roles in visual narrative.

PubMed

Cohn, Neil; Paczynski, Martin

2013-11-01

Agents consistently appear prior to Patients in sentences, manual signs, and drawings, and Agents are responded to faster when presented in visual depictions of events. We hypothesized that this "Agent advantage" reflects Agents' role in event structure. We investigated this question by manipulating the depictions of Agents and Patients in preparatory actions in wordless visual narratives. We found that Agents elicited a greater degree of predictions regarding upcoming events than Patients, that Agents are viewed longer than Patients, independent of serial order, and that visual depictions of actions are processed more quickly following the presentation of an Agent vs. a Patient. Taken together these findings support the notion that Agents initiate the building of event representation. We suggest that Agent First orders facilitate the interpretation of events as they unfold and that the saliency of Agents within visual representations of events is driven by anticipation of upcoming events. Copyright © 2013 Elsevier Inc. All rights reserved.

Distributed Planning in a Mixed-Initiative Environment

DTIC Science & Technology

2008-06-01

Knowledge Sources Control Remote Blackboard Remote Knowledge Sources Remot e Data Remot e Data Java Distributed Blackboard Figure 3 - Distributed...an interface agent or planning agent and the second type is a critic agent. Agents in the DEEP architecture extend and use the Java Agent...chosen because it is fully implemented in Java , and supports these requirements. 2.3.3 Interface Agents Interface agents are the interfaces through

Designing Agent Utilities for Coordinated, Scalable and Robust Multi-Agent Systems

NASA Technical Reports Server (NTRS)

Tumer, Kagan

2005-01-01

Coordinating the behavior of a large number of agents to achieve a system level goal poses unique design challenges. In particular, problems of scaling (number of agents in the thousands to tens of thousands), observability (agents have limited sensing capabilities), and robustness (the agents are unreliable) make it impossible to simply apply methods developed for small multi-agent systems composed of reliable agents. To address these problems, we present an approach based on deriving agent goals that are aligned with the overall system goal, and can be computed using information readily available to the agents. Then, each agent uses a simple reinforcement learning algorithm to pursue its own goals. Because of the way in which those goals are derived, there is no need to use difficult to scale external mechanisms to force collaboration or coordination among the agents, or to ensure that agents actively attempt to appropriate the tasks of agents that suffered failures. To present these results in a concrete setting, we focus on the problem of finding the sub-set of a set of imperfect devices that results in the best aggregate device. This is a large distributed agent coordination problem where each agent (e.g., device) needs to determine whether to be part of the aggregate device. Our results show that the approach proposed in this work provides improvements of over an order of magnitude over both traditional search methods and traditional multi-agent methods. Furthermore, the results show that even in extreme cases of agent failures (i.e., half the agents failed midway through the simulation) the system's performance degrades gracefully and still outperforms a failure-free and centralized search algorithm. The results also show that the gains increase as the size of the system (e.g., number of agents) increases. This latter result is particularly encouraging and suggests that this method is ideally suited for domains where the number of agents is currently in the thousands and will reach tens or hundreds of thousands in the near future.

Prediction, events, and the advantage of Agents: The processing of semantic roles in visual narrative

PubMed Central

Cohn, Neil; Paczynski, Martin

2013-01-01

Agents consistently appear prior to Patients in sentences, manual signs, and drawings, and Agents are responded to faster when presented in visual depictions of events. We hypothesized that this “Agent advantage” reflects Agents’ role in event structure. We investigated this question by manipulating the depictions of Agents and Patients in preparatory actions in a wordless visual narrative. We found that Agents elicited a greater degree of predictions regarding upcoming events than Patients, that Agents are viewed longer than Patients, independent of serial order, and that visual depictions of actions are processed more quickly following the presentation of an Agent versus a Patient. Taken together these findings support the notion that Agents initiate the building of event representation. We suggest that Agent First orders facilitate the interpretation of events as they unfold and that the saliency of Agents within visual representations of events is driven by anticipation of upcoming events. PMID:23959023

22 CFR 51.22 - Passport agents and passport acceptance agents.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 22 Foreign Relations 1 2012-04-01 2012-04-01 false Passport agents and passport acceptance agents. 51.22 Section 51.22 Foreign Relations DEPARTMENT OF STATE NATIONALITY AND PASSPORTS PASSPORTS Application § 51.22 Passport agents and passport acceptance agents. (a) U.S. citizen employees of the...

22 CFR 51.22 - Passport agents and passport acceptance agents.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 22 Foreign Relations 1 2014-04-01 2014-04-01 false Passport agents and passport acceptance agents. 51.22 Section 51.22 Foreign Relations DEPARTMENT OF STATE NATIONALITY AND PASSPORTS PASSPORTS Application § 51.22 Passport agents and passport acceptance agents. (a) U.S. citizen employees of the...

22 CFR 51.22 - Passport agents and passport acceptance agents.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 22 Foreign Relations 1 2013-04-01 2013-04-01 false Passport agents and passport acceptance agents. 51.22 Section 51.22 Foreign Relations DEPARTMENT OF STATE NATIONALITY AND PASSPORTS PASSPORTS Application § 51.22 Passport agents and passport acceptance agents. (a) U.S. citizen employees of the...

22 CFR 51.22 - Passport agents and passport acceptance agents.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 22 Foreign Relations 1 2010-04-01 2010-04-01 false Passport agents and passport acceptance agents. 51.22 Section 51.22 Foreign Relations DEPARTMENT OF STATE NATIONALITY AND PASSPORTS PASSPORTS Application § 51.22 Passport agents and passport acceptance agents. (a) U.S. citizen employees of the...

22 CFR 51.22 - Passport agents and passport acceptance agents.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 22 Foreign Relations 1 2011-04-01 2011-04-01 false Passport agents and passport acceptance agents. 51.22 Section 51.22 Foreign Relations DEPARTMENT OF STATE NATIONALITY AND PASSPORTS PASSPORTS Application § 51.22 Passport agents and passport acceptance agents. (a) U.S. citizen employees of the...

Method of predicting a change in an economy

DOEpatents

Pryor, Richard J [Albuquerque, NM; Basu, Nipa [Albany, NY

2006-01-10

An economy whose activity is to be predicted comprises a plurality of decision makers. Decision makers include, for example, households, government, industry, and banks. The decision makers are represented by agents, where an agent can represent one or more decision makers. Each agent has decision rules that determine the agent's actions. Each agent can affect the economy by affecting variable conditions characteristic of the economy or the internal state of other agents. Agents can communicate actions through messages. On a multiprocessor computer, the agents can be assigned to processing elements.

Method for reactivating catalysts and a method for recycling supercritical fluids used to reactivate the catalysts

DOEpatents

Ginosar, Daniel M.; Thompson, David N.; Anderson, Raymond P.

2008-08-05

A method of reactivating a catalyst, such as a solid catalyst or a liquid catalyst. The method comprises providing a catalyst that is at least partially deactivated by fouling agents. The catalyst is contacted with a fluid reactivating agent that is at or above a critical point of the fluid reactivating agent and is of sufficient density to dissolve impurities. The fluid reactivating agent reacts with at least one fouling agent, releasing the at least one fouling agent from the catalyst. The at least one fouling agent becomes dissolved in the fluid reactivating agent and is subsequently separated or removed from the fluid reactivating agent so that the fluid reactivating agent may be reused. A system for reactivating a catalyst is also disclosed.

Multi-agent planning and scheduling, execution monitoring and incremental rescheduling: Application to motorway traffic

NASA Technical Reports Server (NTRS)

Mourou, Pascal; Fade, Bernard

1992-01-01

This article describes a planning method applicable to agents with great perception and decision-making capabilities and the ability to communicate with other agents. Each agent has a task to fulfill allowing for the actions of other agents in its vicinity. Certain simultaneous actions may cause conflicts because they require the same resource. The agent plans each of its actions and simultaneously transmits these to its neighbors. In a similar way, it receives plans from the other agents and must take account of these plans. The planning method allows us to build a distributed scheduling system. Here, these agents are robot vehicles on a highway communicating by radio. In this environment, conflicts between agents concern the allocation of space in time and are connected with the inertia of the vehicles. Each vehicle made a temporal, spatial, and situated reasoning in order to drive without collision. The flexibility and reactivity of the method presented here allows the agent to generate its plan based on assumptions concerning the other agents and then check these assumptions progressively as plans are received from the other agents. A multi-agent execution monitoring of these plans can be done, using data generated during planning and the multi-agent decision-making algorithm described here. A selective backtrack allows us to perform incremental rescheduling.

Construction of a Learning Agent Handling Its Rewards According to Environmental Situations

NASA Astrophysics Data System (ADS)

Moriyama, Koichi; Numao, Masayuki

The authors aim at constructing an agent which learns appropriate actions in a Multi-Agent environment with and without social dilemmas. For this aim, the agent must have nonrationality that makes it give up its own profit when it should do that. Since there are many studies on rational learning that brings more and more profit, it is desirable to utilize them for constructing the agent. Therefore, we use a reward-handling manner that makes internal evaluation from the agent's rewards, and then the agent learns actions by a rational learning method with the internal evaluation. If the agent has only a fixed manner, however, it does not act well in the environment with and without dilemmas. Thus, the authors equip the agent with several reward-handling manners and criteria for selecting an effective one for the environmental situation. In the case of humans, what generates the internal evaluation is usually called emotion. Hence, this study also aims at throwing light on emotional activities of humans from a constructive view. In this paper, we divide a Multi-Agent environment into three situations and construct an agent having the reward-handling manners and the criteria. We observe that the agent acts well in all the three Multi-Agent situations composed of homogeneous agents.

The highly intelligent virtual agents for modeling financial markets

NASA Astrophysics Data System (ADS)

Yang, G.; Chen, Y.; Huang, J. P.

2016-02-01

Researchers have borrowed many theories from statistical physics, like ensemble, Ising model, etc., to study complex adaptive systems through agent-based modeling. However, one fundamental difference between entities (such as spins) in physics and micro-units in complex adaptive systems is that the latter are usually with high intelligence, such as investors in financial markets. Although highly intelligent virtual agents are essential for agent-based modeling to play a full role in the study of complex adaptive systems, how to create such agents is still an open question. Hence, we propose three principles for designing high artificial intelligence in financial markets and then build a specific class of agents called iAgents based on these three principles. Finally, we evaluate the intelligence of iAgents through virtual index trading in two different stock markets. For comparison, we also include three other types of agents in this contest, namely, random traders, agents from the wealth game (modified on the famous minority game), and agents from an upgraded wealth game. As a result, iAgents perform the best, which gives a well support for the three principles. This work offers a general framework for the further development of agent-based modeling for various kinds of complex adaptive systems.

Computation of the target state and feedback controls for time optimal consensus in multi-agent systems

NASA Astrophysics Data System (ADS)

Mulla, Ameer K.; Patil, Deepak U.; Chakraborty, Debraj

2018-02-01

N identical agents with bounded inputs aim to reach a common target state (consensus) in the minimum possible time. Algorithms for computing this time-optimal consensus point, the control law to be used by each agent and the time taken for the consensus to occur, are proposed. Two types of multi-agent systems are considered, namely (1) coupled single-integrator agents on a plane and, (2) double-integrator agents on a line. At the initial time instant, each agent is assumed to have access to the state information of all the other agents. An algorithm, using convexity of attainable sets and Helly's theorem, is proposed, to compute the final consensus target state and the minimum time to achieve this consensus. Further, parts of the computation are parallelised amongst the agents such that each agent has to perform computations of O(N2) run time complexity. Finally, local feedback time-optimal control laws are synthesised to drive each agent to the target point in minimum time. During this part of the operation, the controller for each agent uses measurements of only its own states and does not need to communicate with any neighbouring agents.

Security patterns and a weighting scheme for mobile agents

NASA Astrophysics Data System (ADS)

Walker, Jessie J.

The notion of mobility has always been a prime factor in human endeavor and achievement. This need to migrate by humans has been distilled into software entities, which are their representatives on distant environments. Software agents are developed to act on behalf of a user. Mobile agents were born from the understanding that many times it was much more useful to move the code (program) to where the resources are located, instead of connecting remotely. Within the mobile agent research community, security has traditionally been the most defining issue facing the community and preventing the paradigm from gaining wide acceptance. There are still numerous difficult problems being addressed with very few practical solutions, such as the malicious host and agent problems. These problems are some of the most active areas of research within the mobile agent community. The major principles, facets, fundamental concepts, techniques and architectures of the field are well understood within the community. This is evident by the many mobile agent systems developed in the last decade that share common core components such as agent management, communication facilities, and mobility services. In other words new mobile agent systems and frameworks do not provide any new insights into agent system architecture or mobility services, agent coordination, communication that could be useful to the agent research community, although these new mobile agent systems do in many instances validate, refine, demonstrate the reuse of many previously proposed and discussed mobile agent research elements. Since mobile agent research for the last decade has been defined by security and related issues, our research into security patterns are within this narrow arena of mobile agent research. The research presented in this thesis examines the issue of mobile agent security from the standpoint of security pattern documented from the universe of mobile agent systems. In addition, we explore how these documented security patterns can be quantitatively compared based on a unique weighting scheme. The scheme is formalized into a theory that can be used improve the development of secure mobile agents and agent-based systems.

Security Measures to Protect Mobile Agents

NASA Astrophysics Data System (ADS)

Dadhich, Piyanka; Govil, M. C.; Dutta, Kamlesh

2010-11-01

The security issues of mobile agent systems have embarrassed its widespread implementation. Mobile agents that move around the network are not safe because the remote hosts that accommodate the agents initiates all kinds of attacks. These hosts try to analyze the agent's decision logic and their accumulated data. So, mobile agent security is the most challenging unsolved problems. The paper analyzes various security measures deeply. Security especially the attacks performed by hosts to the visiting mobile agent (the malicious hosts problem) is a major obstacle that prevents mobile agent technology from being widely adopted. Being the running environment for mobile agent, the host has full control over them and could easily perform many kinds of attacks against them.

Liposome encapsulation of chelating agents

DOEpatents

Rahman, Yueh Erh

1976-01-13

A method for transferring a chelating agent across a cellular membrane by encapsulating the charged chelating agent within liposomes and carrying the liposome-encapsulated chelating agent to the cellular membrane where the liposomes containing the chelating agent will be taken up by the cells, thereby transferring the chelating agent across the cellular membrane. A chelating agent can be introduced into the interior of a cell of a living organism wherein the liposomes will be decomposed, releasing the chelating agent to the interior of the cell. The released chelating agent will complex intracellularly deposited toxic heavy metals, permitting the more soluble metal complex to transfer across the cellular membrane from the cell and subsequently be removed from the living organism.

Mobile agent location in distributed environments

NASA Astrophysics Data System (ADS)

Fountoukis, S. G.; Argyropoulos, I. P.

2012-12-01

An agent is a small program acting on behalf of a user or an application which plays the role of a user. Artificial intelligence can be encapsulated in agents so that they can be capable of both behaving autonomously and showing an elementary decision ability regarding movement and some specific actions. Therefore they are often called autonomous mobile agents. In a distributed system, they can move themselves from one processing node to another through the interconnecting network infrastructure. Their purpose is to collect useful information and to carry it back to their user. Also, agents are used to start, monitor and stop processes running on the individual interconnected processing nodes of computer cluster systems. An agent has a unique id to discriminate itself from other agents and a current position. The position can be expressed as the address of the processing node which currently hosts the agent. Very often, it is necessary for a user, a processing node or another agent to know the current position of an agent in a distributed system. Several procedures and algorithms have been proposed for the purpose of position location of mobile agents. The most basic of all employs a fixed computing node, which acts as agent position repository, receiving messages from all the moving agents and keeping records of their current positions. The fixed node, responds to position queries and informs users, other nodes and other agents about the position of an agent. Herein, a model is proposed that considers pairs and triples of agents instead of single ones. A location method, which is investigated in this paper, attempts to exploit this model.

A Systematic Review of Pedagogical Agents' Persona, Motivation, and Cognitive Load Implications for Learners

ERIC Educational Resources Information Center

Schroeder, Noah L.; Adesope, Olusola O.

2014-01-01

After more than a decade of pedagogical agent research, this review synthesizes the affective implications of learning with pedagogical agents. The review investigates different affective measures within 99 pedagogical agent outcome measures. The results suggest that learners may prefer pedagogical agents compared to non-agent control conditions,…

76 FR 2617 - User Fees Relating to Enrolled Agents and Enrolled Retirement Plan Agents; Hearing Cancellation

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-14

... User Fees Relating to Enrolled Agents and Enrolled Retirement Plan Agents; Hearing Cancellation AGENCY... regulations relating to the imposition of user fees for enrolled agents and enrolled retirement plan agents... FURTHER INFORMATION CONTACT: Richard A. Hurst of the Publications and Regulations Branch, Legal Processing...

The agent-based spatial information semantic grid

NASA Astrophysics Data System (ADS)

Cui, Wei; Zhu, YaQiong; Zhou, Yong; Li, Deren

2006-10-01

Analyzing the characteristic of multi-Agent and geographic Ontology, The concept of the Agent-based Spatial Information Semantic Grid (ASISG) is defined and the architecture of the ASISG is advanced. ASISG is composed with Multi-Agents and geographic Ontology. The Multi-Agent Systems are composed with User Agents, General Ontology Agent, Geo-Agents, Broker Agents, Resource Agents, Spatial Data Analysis Agents, Spatial Data Access Agents, Task Execution Agent and Monitor Agent. The architecture of ASISG have three layers, they are the fabric layer, the grid management layer and the application layer. The fabric layer what is composed with Data Access Agent, Resource Agent and Geo-Agent encapsulates the data of spatial information system so that exhibits a conceptual interface for the Grid management layer. The Grid management layer, which is composed with General Ontology Agent, Task Execution Agent and Monitor Agent and Data Analysis Agent, used a hybrid method to manage all resources that were registered in a General Ontology Agent that is described by a General Ontology System. The hybrid method is assembled by resource dissemination and resource discovery. The resource dissemination push resource from Local Ontology Agent to General Ontology Agent and the resource discovery pull resource from the General Ontology Agent to Local Ontology Agents. The Local Ontology Agent is derived from special domain and describes the semantic information of local GIS. The nature of the Local Ontology Agents can be filtrated to construct a virtual organization what could provides a global scheme. The virtual organization lightens the burdens of guests because they need not search information site by site manually. The application layer what is composed with User Agent, Geo-Agent and Task Execution Agent can apply a corresponding interface to a domain user. The functions that ASISG should provide are: 1) It integrates different spatial information systems on the semantic The Grid management layer establishes a virtual environment that integrates seamlessly all GIS notes. 2) When the resource management system searches data on different spatial information systems, it transfers the meaning of different Local Ontology Agents rather than access data directly. So the ability of search and query can be said to be on the semantic level. 3) The data access procedure is transparent to guests, that is, they could access the information from remote site as current disk because the General Ontology Agent could automatically link data by the Data Agents that link the Ontology concept to GIS data. 4) The capability of processing massive spatial data. Storing, accessing and managing massive spatial data from TB to PB; efficiently analyzing and processing spatial data to produce model, information and knowledge; and providing 3D and multimedia visualization services. 5) The capability of high performance computing and processing on spatial information. Solving spatial problems with high precision, high quality, and on a large scale; and process spatial information in real time or on time, with high-speed and high efficiency. 6) The capability of sharing spatial resources. The distributed heterogeneous spatial information resources are Shared and realizing integrated and inter-operated on semantic level, so as to make best use of spatial information resources,such as computing resources, storage devices, spatial data (integrating from GIS, RS and GPS), spatial applications and services, GIS platforms, 7) The capability of integrating legacy GIS system. A ASISG can not only be used to construct new advanced spatial application systems, but also integrate legacy GIS system, so as to keep extensibility and inheritance and guarantee investment of users. 8) The capability of collaboration. Large-scale spatial information applications and services always involve different departments in different geographic places, so remote and uniform services are needed. 9) The capability of supporting integration of heterogeneous systems. Large-scale spatial information systems are always synthetically applications, so ASISG should provide interoperation and consistency through adopting open and applied technology standards. 10) The capability of adapting dynamic changes. Business requirements, application patterns, management strategies, and IT products always change endlessly for any departments, so ASISG should be self-adaptive. Two examples are provided in this paper, those examples provide a detailed way on how you design your semantic grid based on Multi-Agent systems and Ontology. In conclusion, the semantic grid of spatial information system could improve the ability of the integration and interoperability of spatial information grid.

Applications of Multi-Agent Technology to Power Systems

NASA Astrophysics Data System (ADS)

Nagata, Takeshi

Currently, agents are focus of intense on many sub-fields of computer science and artificial intelligence. Agents are being used in an increasingly wide variety of applications. Many important computing applications such as planning, process control, communication networks and concurrent systems will benefit from using multi-agent system approach. A multi-agent system is a structure given by an environment together with a set of artificial agents capable to act on this environment. Multi-agent models are oriented towards interactions, collaborative phenomena, and autonomy. This article presents the applications of multi-agent technology to the power systems.

DYNACLIPS (DYNAmic CLIPS): A dynamic knowledge exchange tool for intelligent agents

NASA Technical Reports Server (NTRS)

Cengeloglu, Yilmaz; Khajenoori, Soheil; Linton, Darrell

1994-01-01

In a dynamic environment, intelligent agents must be responsive to unanticipated conditions. When such conditions occur, an intelligent agent may have to stop a previously planned and scheduled course of actions and replan, reschedule, start new activities and initiate a new problem solving process to successfully respond to the new conditions. Problems occur when an intelligent agent does not have enough knowledge to properly respond to the new situation. DYNACLIPS is an implementation of a framework for dynamic knowledge exchange among intelligent agents. Each intelligent agent is a CLIPS shell and runs a separate process under SunOS operating system. Intelligent agents can exchange facts, rules, and CLIPS commands at run time. Knowledge exchange among intelligent agents at run times does not effect execution of either sender and receiver intelligent agent. Intelligent agents can keep the knowledge temporarily or permanently. In other words, knowledge exchange among intelligent agents would allow for a form of learning to be accomplished.

Social Dynamics in Web Page through Inter-Agent Interaction

NASA Astrophysics Data System (ADS)

Takeuchi, Yugo; Katagiri, Yasuhiro

Social persuasion abounds in human-human interactions. Attitudes and behaviors of people are invariably influenced by the attitudes and behaviors of other people as well as our social roles/relationships toward them. In the pedagogic scene, the relationship between teacher and learner produces one of the most typical interactions, in which the teacher makes the learner spontaneously study what he/she teaches. This study is an attempt to elucidate the nature and effectiveness of social persuasion in human-computer interaction environments. We focus on the social dynamics of multi-party interactions that involve both human-agent and inter-agent interactions. An experiment is conducted in a virtual web-instruction setting employing two types of agents: conductor agents who accompany and guide each learner throughout his/her learning sessions, and domain-expert agents who provide explanations and instructions for each stage of the instructional materials. In this experiment, subjects are assigned two experimental conditions: the authorized condition, in which an agent respectfully interacts with another agent, and the non-authorized condition, in which an agent carelessly interacts with another agent. The results indicate performance improvements in the authorized condition of inter-agent interactions. An analysis is given from the perspective of the transfer of authority from inter-agent to human-agent interactions based on social conformity. We argue for pedagogic advantages of social dynamics created by multiple animated character agents.

Agent-Based Crowd Simulation Considering Emotion Contagion for Emergency Evacuation Problem

NASA Astrophysics Data System (ADS)

Faroqi, H.; Mesgari, M.-S.

2015-12-01

During emergencies, emotions greatly affect human behaviour. For more realistic multi-agent systems in simulations of emergency evacuations, it is important to incorporate emotions and their effects on the agents. In few words, emotional contagion is a process in which a person or group influences the emotions or behavior of another person or group through the conscious or unconscious induction of emotion states and behavioral attitudes. In this study, we simulate an emergency situation in an open square area with three exits considering Adults and Children agents with different behavior. Also, Security agents are considered in order to guide Adults and Children for finding the exits and be calm. Six levels of emotion levels are considered for each agent in different scenarios and situations. The agent-based simulated model initialize with the random scattering of agent populations and then when an alarm occurs, each agent react to the situation based on its and neighbors current circumstances. The main goal of each agent is firstly to find the exit, and then help other agents to find their ways. Numbers of exited agents along with their emotion levels and damaged agents are compared in different scenarios with different initialization in order to evaluate the achieved results of the simulated model. NetLogo 5.2 is used as the multi-agent simulation framework with R language as the developing language.

Iodinated contrast media and contrast-induced nephropathy: is there a preferred cost-effective agent?

PubMed

Sharma, Samin K

2008-05-01

Over 20 years have passed since the introduction of the tri-iodinated low-osmolar nonionic contrast agents such as iopamidol, iohexol, ioversol and iopromide. During this time, most cardiology practices have switched to these nonionic agents to avoid the nuisance side effects and cardiac adverse events associated with the older ionic contrast agents. Although the improved tolerability of the nonionic agents is generally attributed to their decreased osmolality (approximately half that of the older ionic contrast agents), in fact, these contrast agents also differ from the older agents in their ionicity, viscosity and direct chemotoxicity. The impact of these properties on safety, together with cost differences, should be considered when selecting a contrast agent.

Intelligent Agent Architectures: Reactive Planning Testbed

NASA Technical Reports Server (NTRS)

Rosenschein, Stanley J.; Kahn, Philip

1993-01-01

An Integrated Agent Architecture (IAA) is a framework or paradigm for constructing intelligent agents. Intelligent agents are collections of sensors, computers, and effectors that interact with their environments in real time in goal-directed ways. Because of the complexity involved in designing intelligent agents, it has been found useful to approach the construction of agents with some organizing principle, theory, or paradigm that gives shape to the agent's components and structures their relationships. Given the wide variety of approaches being taken in the field, the question naturally arises: Is there a way to compare and evaluate these approaches? The purpose of the present work is to develop common benchmark tasks and evaluation metrics to which intelligent agents, including complex robotic agents, constructed using various architectural approaches can be subjected.

Modeling of a production system using the multi-agent approach

NASA Astrophysics Data System (ADS)

Gwiazda, A.; Sękala, A.; Banaś, W.

2017-08-01

The method that allows for the analysis of complex systems is a multi-agent simulation. The multi-agent simulation (Agent-based modeling and simulation - ABMS) is modeling of complex systems consisting of independent agents. In the case of the model of the production system agents may be manufactured pieces set apart from other types of agents like machine tools, conveyors or replacements stands. Agents are magazines and buffers. More generally speaking, the agents in the model can be single individuals, but you can also be defined as agents of collective entities. They are allowed hierarchical structures. It means that a single agent could belong to a certain class. Depending on the needs of the agent may also be a natural or physical resource. From a technical point of view, the agent is a bundle of data and rules describing its behavior in different situations. Agents can be autonomous or non-autonomous in making the decision about the types of classes of agents, class sizes and types of connections between elements of the system. Multi-agent modeling is a very flexible technique for modeling and model creating in the convention that could be adapted to any research problem analyzed from different points of views. One of the major problems associated with the organization of production is the spatial organization of the production process. Secondly, it is important to include the optimal scheduling. For this purpose use can approach multi-purposeful. In this regard, the model of the production process will refer to the design and scheduling of production space for four different elements. The program system was developed in the environment NetLogo. It was also used elements of artificial intelligence. The main agent represents the manufactured pieces that, according to previously assumed rules, generate the technological route and allow preprint the schedule of that line. Machine lines, reorientation stands, conveyors and transport devices also represent the other type of agent that are utilized in the described simulation. The article presents the idea of an integrated program approach and shows the resulting production layout as a virtual model. This model was developed in the NetLogo multi-agent program environment.

Using an agent-based model to analyze the dynamic communication network of the immune response

PubMed Central

2011-01-01

Background The immune system behaves like a complex, dynamic network with interacting elements including leukocytes, cytokines, and chemokines. While the immune system is broadly distributed, leukocytes must communicate effectively to respond to a pathological challenge. The Basic Immune Simulator 2010 contains agents representing leukocytes and tissue cells, signals representing cytokines, chemokines, and pathogens, and virtual spaces representing organ tissue, lymphoid tissue, and blood. Agents interact dynamically in the compartments in response to infection of the virtual tissue. Agent behavior is imposed by logical rules derived from the scientific literature. The model captured the agent-to-agent contact history, and from this the network topology and the interactions resulting in successful versus failed viral clearance were identified. This model served to integrate existing knowledge and allowed us to examine the immune response from a novel perspective directed at exploiting complex dynamics, ultimately for the design of therapeutic interventions. Results Analyzing the evolution of agent-agent interactions at incremental time points from identical initial conditions revealed novel features of immune communication associated with successful and failed outcomes. There were fewer contacts between agents for simulations ending in viral elimination (win) versus persistent infection (loss), due to the removal of infected agents. However, early cellular interactions preceded successful clearance of infection. Specifically, more Dendritic Agent interactions with TCell and BCell Agents, and more BCell Agent interactions with TCell Agents early in the simulation were associated with the immune win outcome. The Dendritic Agents greatly influenced the outcome, confirming them as hub agents of the immune network. In addition, unexpectedly high frequencies of Dendritic Agent-self interactions occurred in the lymphoid compartment late in the loss outcomes. Conclusions An agent-based model capturing several key aspects of complex system dynamics was used to study the emergent properties of the immune response to viral infection. Specific patterns of interactions between leukocyte agents occurring early in the response significantly improved outcome. More interactions at later stages correlated with persistent inflammation and infection. These simulation experiments highlight the importance of commonly overlooked aspects of the immune response and provide insight into these processes at a resolution level exceeding the capabilities of current laboratory technologies. PMID:21247471

Nanoparticles as potential new generation broad spectrum antimicrobial agents.

PubMed

Yah, Clarence S; Simate, Geoffrey S

2015-09-02

The rapid emergence of antimicrobial resistant strains to conventional antimicrobial agents has complicated and prolonged infection treatment and increased mortality risk globally. Furthermore, some of the conventional antimicrobial agents are unable to cross certain cell membranes thus, restricting treatment of intracellular pathogens. Therefore, the disease-causing-organisms tend to persist in these cells. However, the emergence of nanoparticle (NP) technology has come with the promising broad spectrum NP-antimicrobial agents due to their vast physiochemical and functionalization properties. In fact, NP-antimicrobial agents are able to unlock the restrictions experienced by conventional antimicrobial agents. This review discusses the status quo of NP-antimicrobial agents as potent broad spectrum antimicrobial agents, sterilization and wound healing agents, and sustained inhibitors of intracellular pathogens. Indeed, the perspective of developing potent NP-antimicrobial agents that carry multiple-functionality will revolutionize clinical medicine and play a significant role in alleviating disease burden.

An Agent-Based Data Mining System for Ontology Evolution

NASA Astrophysics Data System (ADS)

Hadzic, Maja; Dillon, Darshan

We have developed an evidence-based mental health ontological model that represents mental health in multiple dimensions. The ongoing addition of new mental health knowledge requires a continual update of the Mental Health Ontology. In this paper, we describe how the ontology evolution can be realized using a multi-agent system in combination with data mining algorithms. We use the TICSA methodology to design this multi-agent system which is composed of four different types of agents: Information agent, Data Warehouse agent, Data Mining agents and Ontology agent. We use UML 2.1 sequence diagrams to model the collaborative nature of the agents and a UML 2.1 composite structure diagram to model the structure of individual agents. The Mental Heath Ontology has the potential to underpin various mental health research experiments of a collaborative nature which are greatly needed in times of increasing mental distress and illness.

Topical antifungal agents: an update.

PubMed

Diehl, K B

1996-10-01

So many topical antifungal agents have been introduced that it has become very difficult to select the proper agent for a given infection. Nonspecific agents have been available for many years, and they are still effective in many situations. These agents include Whitfield's ointment, Castellani paint, gentian violet, potassium permanganate, undecylenic acid and selenium sulfide. Specific antifungal agents include, among others, the polyenes (nystatin, amphotericin B), the imidazoles (metronidazole, clotrimazole) and the allylamines (terbinafine, naftifine). Although the choice of an antifungal agent should be based on an accurate diagnosis, many clinicians believe that topical miconazole is a relatively effective agent for the treatment of most mycotic infections. Terbinafine and other newer drugs have primary fungicidal effects. Compared with older antifungal agents, these newer drugs can be used in lower concentrations and shorter therapeutic courses. Studies are needed to evaluate the clinical efficacies and cost advantages of both newer and traditional agents.

Effects of competition and cooperation interaction between agents on networks in the presence of a market capacity

NASA Astrophysics Data System (ADS)

Sonubi, A.; Arcagni, A.; Stefani, S.; Ausloos, M.

2016-08-01

A network effect is introduced taking into account competition, cooperation, and mixed-type interaction among agents along a generalized Verhulst-Lotka-Volterra model. It is also argued that the presence of a market capacity undoubtedly enforces a definite limit on the agent's size growth. The state stability of triadic agents, i.e., the most basic network plaquette, is investigated analytically for possible scenarios, through a fixed-point analysis. It is discovered that: (i) market demand is only satisfied for full competition when one agent monopolizes the market; (ii) growth of agent size is encouraged in full cooperation; (iii) collaboration among agents to compete against one single agent may result in the disappearance of this single agent out of the market; and (iv) cooperating with two rivals may become a growth strategy for an intelligent agent.

Effects of competition and cooperation interaction between agents on networks in the presence of a market capacity.

PubMed

Sonubi, A; Arcagni, A; Stefani, S; Ausloos, M

2016-08-01

A network effect is introduced taking into account competition, cooperation, and mixed-type interaction among agents along a generalized Verhulst-Lotka-Volterra model. It is also argued that the presence of a market capacity undoubtedly enforces a definite limit on the agent's size growth. The state stability of triadic agents, i.e., the most basic network plaquette, is investigated analytically for possible scenarios, through a fixed-point analysis. It is discovered that: (i) market demand is only satisfied for full competition when one agent monopolizes the market; (ii) growth of agent size is encouraged in full cooperation; (iii) collaboration among agents to compete against one single agent may result in the disappearance of this single agent out of the market; and (iv) cooperating with two rivals may become a growth strategy for an intelligent agent.

Department of Defense Chemical, Biological, Defense Program, Annual Report to Congress, March 2005

DTIC Science & Technology

2005-03-01

nerve agents ( GA , GB, GD, and GF), V type nerve agents , and H (mustard) type blister agents . M8 paper can identify agents through...The M21 RSCAAL is an automatic scanning, passive infrared sensor that detects nerve ( GA , GB, and GD) and blister (H and L) agent vapor clouds...Chief of Staff for Programs GA – tabun, a nerve agent GAO – General Accounting Office GB – sarin, a nerve agent GD – soman, a nerve

Contrast enhanced spectroscopic optical coherence tomography

NASA Technical Reports Server (NTRS)

Xu, Chenyang (Inventor); Boppart, Stephen A. (Inventor)

2010-01-01

A method of forming an image of a sample includes performing SOCT on a sample. The sample may include a contrast agent, which may include an absorbing agent and/or a scattering agent. A method of forming an image of tissue may include selecting a contrast agent, delivering the contrast agent to the tissue, acquiring SOCT data from the tissue, and converting the SOCT data into an image. The contributions to the SOCT data of an absorbing agent and a scattering agent in a sample may be quantified separately.

Opinion evolution influenced by informed agents

NASA Astrophysics Data System (ADS)

Fan, Kangqi; Pedrycz, Witold

2016-11-01

Guiding public opinions toward a pre-set target by informed agents can be a strategy adopted in some practical applications. The informed agents are common agents who are employed or chosen to spread the pre-set opinion. In this work, we propose a social judgment based opinion (SJBO) dynamics model to explore the opinion evolution under the influence of informed agents. The SJBO model distinguishes between inner opinions and observable choices, and incorporates both the compromise between similar opinions and the repulsion between dissimilar opinions. Three choices (support, opposition, and remaining undecided) are considered in the SJBO model. Using the SJBO model, both the inner opinions and the observable choices can be tracked during the opinion evolution process. The simulation results indicate that if the exchanges of inner opinions among agents are not available, the effect of informed agents is mainly dependent on the characteristics of regular agents, including the assimilation threshold, decay threshold, and initial opinions. Increasing the assimilation threshold and decay threshold can improve the guiding effectiveness of informed agents. Moreover, if the initial opinions of regular agents are close to null, the full and unanimous consensus at the pre-set opinion can be realized, indicating that, to maximize the influence of informed agents, the guidance should be started when regular agents have little knowledge about a subject under consideration. If the regular agents have had clear opinions, the full and unanimous consensus at the pre-set opinion cannot be achieved. However, the introduction of informed agents can make the majority of agents choose the pre-set opinion.

Computational memory architectures for autobiographic agents interacting in a complex virtual environment: a working model

NASA Astrophysics Data System (ADS)

Ho, Wan Ching; Dautenhahn, Kerstin; Nehaniv, Chrystopher

2008-03-01

In this paper, we discuss the concept of autobiographic agent and how memory may extend an agent's temporal horizon and increase its adaptability. These concepts are applied to an implementation of a scenario where agents are interacting in a complex virtual artificial life environment. We present computational memory architectures for autobiographic virtual agents that enable agents to retrieve meaningful information from their dynamic memories which increases their adaptation and survival in the environment. The design of the memory architectures, the agents, and the virtual environment are described in detail. Next, a series of experimental studies and their results are presented which show the adaptive advantage of autobiographic memory, i.e. from remembering significant experiences. Also, in a multi-agent scenario where agents can communicate via stories based on their autobiographic memory, it is found that new adaptive behaviours can emerge from an individual's reinterpretation of experiences received from other agents whereby higher communication frequency yields better group performance. An interface is described that visualises the memory contents of an agent. From an observer perspective, the agents' behaviours can be understood as individually structured, and temporally grounded, and, with the communication of experience, can be seen to rely on emergent mixed narrative reconstructions combining the experiences of several agents. This research leads to insights into how bottom-up story-telling and autobiographic reconstruction in autonomous, adaptive agents allow temporally grounded behaviour to emerge. The article concludes with a discussion of possible implications of this research direction for future autobiographic, narrative agents.

Multi-Agent Information Classification Using Dynamic Acquaintance Lists.

ERIC Educational Resources Information Center

Mukhopadhyay, Snehasis; Peng, Shengquan; Raje, Rajeev; Palakal, Mathew; Mostafa, Javed

2003-01-01

Discussion of automated information services focuses on information classification and collaborative agents, i.e. intelligent computer programs. Highlights include multi-agent systems; distributed artificial intelligence; thesauri; document representation and classification; agent modeling; acquaintances, or remote agents discovered through…

The Effects of Peer-Like and Expert-Like Pedagogical Agents on Learners' Agent Perceptions, Task-Related Attitudes, and Learning Achievement

ERIC Educational Resources Information Center

Liew, Tze Wei; Tan, Su-Mae; Jayothisa, Chandrika

2013-01-01

The present study examined the impact of peer-like and expert-like agent stereotypes, as operationalized by agent's image and voice, on learners' agent perceptions, task-related attitudes, and learning achievement. 56 university freshmen (23 males and 33 females) interacted with either the peer-like agent (female college student) or the…

Introduction to Agent Mining Interaction and Integration

NASA Astrophysics Data System (ADS)

Cao, Longbing

In recent years, more and more researchers have been involved in research on both agent technology and data mining. A clear disciplinary effort has been activated toward removing the boundary between them, that is the interaction and integration between agent technology and data mining. We refer this to agent mining as a new area. The marriage of agents and data mining is driven by challenges faced by both communities, and the need of developing more advanced intelligence, information processing and systems. This chapter presents an overall picture of agent mining from the perspective of positioning it as an emerging area. We summarize the main driving forces, complementary essence, disciplinary framework, applications, case studies, and trends and directions, as well as brief observation on agent-driven data mining, data mining-driven agents, and mutual issues in agent mining. Arguably, we draw the following conclusions: (1) agent mining emerges as a new area in the scientific family, (2) both agent technology and data mining can greatly benefit from agent mining, (3) it is very promising to result in additional advancement in intelligent information processing and systems. However, as a new open area, there are many issues waiting for research and development from theoretical, technological and practical perspectives.

Hybrid evolutionary computing model for mobile agents of wireless Internet multimedia

NASA Astrophysics Data System (ADS)

Hortos, William S.

2001-03-01

The ecosystem is used as an evolutionary paradigm of natural laws for the distributed information retrieval via mobile agents to allow the computational load to be added to server nodes of wireless networks, while reducing the traffic on communication links. Based on the Food Web model, a set of computational rules of natural balance form the outer stage to control the evolution of mobile agents providing multimedia services with a wireless Internet protocol WIP. The evolutionary model shows how mobile agents should behave with the WIP, in particular, how mobile agents can cooperate, compete and learn from each other, based on an underlying competition for radio network resources to establish the wireless connections to support the quality of service QoS of user requests. Mobile agents are also allowed to clone themselves, propagate and communicate with other agents. A two-layer model is proposed for agent evolution: the outer layer is based on the law of natural balancing, the inner layer is based on a discrete version of a Kohonen self-organizing feature map SOFM to distribute network resources to meet QoS requirements. The former is embedded in the higher OSI layers of the WIP, while the latter is used in the resource management procedures of Layer 2 and 3 of the protocol. Algorithms for the distributed computation of mobile agent evolutionary behavior are developed by adding a learning state to the agent evolution state diagram. When an agent is in an indeterminate state, it can communicate to other agents. Computing models can be replicated from other agents. Then the agents transitions to the mutating state to wait for a new information-retrieval goal. When a wireless terminal or station lacks a network resource, an agent in the suspending state can change its policy to submit to the environment before it transitions to the searching state. The agents learn the facts of agent state information entered into an external database. In the cloning process, two agents on a host station sharing a common goal can be merged or married to compose a new agent. Application of the two-layer set of algorithms for mobile agent evolution, performed in a distributed processing environment, is made to the QoS management functions of the IP multimedia IM sub-network of the third generation 3G Wideband Code-division Multiple Access W-CDMA wireless network.

Detection of Alkylating Agents using Electrical and Mechanical Means

NASA Astrophysics Data System (ADS)

Gerchikov, Yulia; Borzin, Elena; Gannot, Yair; Shemesh, Ariel; Meltzman, Shai; Hertzog-Ronen, Carmit; Tal, Shay; Stolyarova, Sara; Nemirovsky, Yael; Tessler, Nir; Eichen, Yoav

2011-08-01

Alkylating agents are reactive molecules having at least one polar bond between a carbon atom and a good leaving group. These often simple molecules are frequently used in organic synthesis, as sterilizing agents in agriculture and even as anticancer agents in medicine. Unfortunately, for over a century, some of the highly reactive alkylating agents are also being used as blister chemical warfare agents. Being relatively simple to make, the risk is that these will be applied by terrorists as poor people warfare agents. The detection and identification of such alkylating agents is not a simple task because of their high reactivity and simple structure of the reactive site. Here we report on new approaches to the detection and identification of such alkylating agents using electrical (organic field effect transistors) and mechanical (microcantilevers) means.

Consensus pursuit of heterogeneous multi-agent systems under a directed acyclic graph

NASA Astrophysics Data System (ADS)

Yan, Jing; Guan, Xin-Ping; Luo, Xiao-Yuan

2011-04-01

This paper is concerned with the cooperative target pursuit problem by multiple agents based on directed acyclic graph. The target appears at a random location and moves only when sensed by the agents, and agents will pursue the target once they detect its existence. Since the ability of each agent may be different, we consider the heterogeneous multi-agent systems. According to the topology of the multi-agent systems, a novel consensus-based control law is proposed, where the target and agents are modeled as a leader and followers, respectively. Based on Mason's rule and signal flow graph analysis, the convergence conditions are provided to show that the agents can catch the target in a finite time. Finally, simulation studies are provided to verify the effectiveness of the proposed approach.

Hierarchical Controlled Remote State Preparation by Using a Four-Qubit Cluster State

NASA Astrophysics Data System (ADS)

Ma, Peng-Cheng; Chen, Gui-Bin; Li, Xiao-Wei; Zhan, You-Bang

2018-06-01

We propose a scheme for hierarchical controlled remote preparation of an arbitrary single-qubit state via a four-qubit cluster state as the quantum channel. In this scheme, a sender wishes to help three agents to remotely prepare a quantum state, respectively. The three agents are divided into two grades, that is, an agent is in the upper grade and other two agents are in the lower grade. In this process of remote state preparation, the agent of the upper grade only needs the assistance of any one of the other two agents for recovering the sender's original state, while an agent of the lower grade needs the collaboration of all the other two agents. In other words, the agents of two grades have different authorities to reconstruct sender's original state.

Method and apparatus to characterize ultrasonically reflective contrast agents

NASA Technical Reports Server (NTRS)

Pretlow, Robert A., III (Inventor)

1993-01-01

A method and apparatus for characterizing the time and frequency response of an ultrasonically reflective contrast agent is disclosed. An ultrasonically reflective contrast agent is injected, under constant pressure, into a fluid flowing through a pump flow circuit. The fluid and the ultrasonically reflective contrast agent are uniformly mixed in a mixing chamber, and the uniform mixture is passed through a contrast agent chamber. The contrast agent chamber is acoustically and axially interposed between an ultrasonic transducer chamber and an acoustic isolation chamber. A pulse of ultrasonic energy is transmitted into the contrast agent chamber from the ultrasonic transducer chamber. An echo waveform is received from the ultrasonically reflective contrast agent, and it is analyzed to determine the time and frequency response of the ultrasonically reflective contrast agent.

Modelling of robotic work cells using agent based-approach

NASA Astrophysics Data System (ADS)

Sękala, A.; Banaś, W.; Gwiazda, A.; Monica, Z.; Kost, G.; Hryniewicz, P.

2016-08-01

In the case of modern manufacturing systems the requirements, both according the scope and according characteristics of technical procedures are dynamically changing. This results in production system organization inability to keep up with changes in a market demand. Accordingly, there is a need for new design methods, characterized, on the one hand with a high efficiency and on the other with the adequate level of the generated organizational solutions. One of the tools that could be used for this purpose is the concept of agent systems. These systems are the tools of artificial intelligence. They allow assigning to agents the proper domains of procedures and knowledge so that they represent in a self-organizing system of an agent environment, components of a real system. The agent-based system for modelling robotic work cell should be designed taking into consideration many limitations considered with the characteristic of this production unit. It is possible to distinguish some grouped of structural components that constitute such a system. This confirms the structural complexity of a work cell as a specific production system. So it is necessary to develop agents depicting various aspects of the work cell structure. The main groups of agents that are used to model a robotic work cell should at least include next pattern representatives: machine tool agents, auxiliary equipment agents, robots agents, transport equipment agents, organizational agents as well as data and knowledge bases agents. In this way it is possible to create the holarchy of the agent-based system.

Agent Reward Shaping for Alleviating Traffic Congestion

NASA Technical Reports Server (NTRS)

Tumer, Kagan; Agogino, Adrian

2006-01-01

Traffic congestion problems provide a unique environment to study how multi-agent systems promote desired system level behavior. What is particularly interesting in this class of problems is that no individual action is intrinsically "bad" for the system but that combinations of actions among agents lead to undesirable outcomes, As a consequence, agents need to learn how to coordinate their actions with those of other agents, rather than learn a particular set of "good" actions. This problem is ubiquitous in various traffic problems, including selecting departure times for commuters, routes for airlines, and paths for data routers. In this paper we present a multi-agent approach to two traffic problems, where far each driver, an agent selects the most suitable action using reinforcement learning. The agent rewards are based on concepts from collectives and aim to provide the agents with rewards that are both easy to learn and that if learned, lead to good system level behavior. In the first problem, we study how agents learn the best departure times of drivers in a daily commuting environment and how following those departure times alleviates congestion. In the second problem, we study how agents learn to select desirable routes to improve traffic flow and minimize delays for. all drivers.. In both sets of experiments,. agents using collective-based rewards produced near optimal performance (93-96% of optimal) whereas agents using system rewards (63-68%) barely outperformed random action selection (62-64%) and agents using local rewards (48-72%) performed worse than random in some instances.

Polydopamine-coated capsules

DOE Office of Scientific and Technical Information (OSTI.GOV)

White, Scott R.; Sottos, Nancy R.; Kang, Sen

One aspect of the invention is a polymer material comprising a capsule coated with PDA. In certain embodiments, the capsule encapsulates a functional agent. The encapsulated functional agent may be an indicating agent, healing agent, protecting agent, pharmaceutical drug, food additive, or a combination thereof.

40 CFR 300.915 - Data requirements.

Code of Federal Regulations, 2010 CFR

2010-07-01

... this section. (d) Bioremediation Agents. (1) Name, brand, or trademark, if any, under which the agent...) Bioremediation Agent Effectiveness. Use bioremediation agent effectiveness test methods described in appendix C to part 300. (8) Bioremediation Agent Toxicity [Reserved]. (9) Biological additives. (i) For...

[Utilization of polymeric micelle magnetic resonance imaging (MRI) contrast agent for theranostic system].

PubMed

Shiraishi, Kouichi

2013-01-01

We applied a polymeric micelle carrier system for the targeting of a magnetic resonance imaging (MRI) contrast agent. Prepared polymeric micelle MRI contrast agent exhibited a long circulation characteristic in blood, and considerable amount of the contrast agent was found to accumulate in colon 26 solid tumor by the EPR effect. The signal intensities of tumor area showed 2-folds increase in T1-weighted images at 24 h after i.v. injection. To observe enhancement of the EPR effect by Cderiv pretreatment on tumor targeting, we used the contrast agent for the evaluation by means of MRI. Cderiv pretreatment significantly enhanced tumor accumulation of the contrast agent. Interestingly, very high signal intensity in tumor region was found at 24 h after the contrast agent injection in Cderiv pretreated mice. The contrast agent visualized a microenvironmental change in tumor. These results indicate that the contrast agent exhibits potential use for tumor diagnostic agent. To combine with a polymeric micelle carrier system for therapeutic agent, the usage of the combination makes a new concept of "theranostic" for a better cancer treatment.

United States Army Biomedical Research and Development Laboratory Annual Progress Report FY90

DTIC Science & Technology

1991-01-01

pesticide . Parallel and follow-on studies will include hydrolysis products of nerve agents , vesicants, and agents of...Division FO Fog oil FORSCOM U.S. Army Forces Command FY Fiscal year 249 GA The nerve agent tabun GB The nerve agent soman GD The nerve agent sarin GLP... Nerve Agents , Industrial Hygiene Sampling, Microbiology, Combustion Products, Liquid Gun Propellant, Organic Chemistry, Inorganic

A Systems Approach to Depaint Chemistry

DTIC Science & Technology

2009-02-01

continuous colored film by curing through solvent evaporation, oxidation, catylization or other means. – Vehicle: Film former, binder, resin or polymer...impart large changes in properties. – Suspending agents – Driers – Anti-Skinning Agents – Wetting Agents – Anti- Foaming Agents – Coalescing Agents ...volatile stripper inside the coating. Paint Release Agent Coating Removal Mechanism Zone1: PRA Layer Zone2: PRA Initial Permeation into coating system Epoxy

GC-MS and LC-MS analysis of nerve agents in body fluids: intra-laboratory verification test using spiked plasma and urine samples.

PubMed

Koller, Marianne; Becker, Christian; Thiermann, Horst; Worek, Franz

2010-05-15

The purpose of this study was to check the applicability of different analytical methods for the identification of unknown nerve agents in human body fluids. Plasma and urine samples were spiked with nerve agents (plasma) or with their metabolites (urine) or were left blank. Seven random samples (35% of all samples) were selected for the verification test. Plasma was worked up for unchanged nerve agents and for regenerated nerve agents after fluoride-induced reactivation of nerve agent-inhibited butyrylcholinesterase. Both extracts were analysed by GC-MS. Metabolites were extracted from plasma and urine, respectively, and were analysed by LC-MS. The urinary metabolites and two blank samples could be identified without further measurements, plasma metabolites and blanks were identified in six of seven samples. The analysis of unchanged nerve agent provided five agents/blanks and the sixth agent after further investigation. The determination of the regenerated agents also provided only five clear findings during the first screening because of a rather noisy baseline. Therefore, the sample preparation was extended by a size exclusion step performed before addition of fluoride which visibly reduced baseline noise and thus improved identification of the two missing agents. The test clearly showed that verification should be performed by analysing more than one biomarker to ensure identification of the agent(s). Copyright (c) 2010 Elsevier B.V. All rights reserved.

Chemical Action of Halogenated Agents in Fire Extinguishing

NASA Technical Reports Server (NTRS)

Belles, Frank E.

1955-01-01

The action of halogenated agents in preventing flame propagation in fuel-air mixtures in laboratory tests is discussed in terms of a possible chemical mechanism. The mechanism chosen is that of chain-breaking reactions between agent and active particles (hydrogen and oxygen atoms and hydroxyl radicsls). Data from the literature on the flammability peaks of n-heptane agent-air mixtures are treated. Ratings of agent effectiveness in terms of the fuel equivalent of the agent, based on both fuel and agent concentrations at the peak, are proposed as preferable to ratings in terms of agent concentration alone. These fuel-equivalent ratings are roughly correlated by reactivities assigned to halogen and hydrogen atoms in the agent molecules. It is concluded that the presence of hydrogen in agent need not reduce its fire-fighting ability, provided there is enough halogen to make the agent nonflammable. A method is presented for estimating from quenching-distance data a rate constant for the reaction of agent with active particles. A quantitative result is obtained for methyl bromide. This rate constant predicts the observed peak concentration of methyl bromide quite well. However, more data are needed to prove the validity of the method. The assumption that hal.ogenatedagents act mainly by chain-bresking reactions with active particles is consistent with the experimental facts and should help guide the selection of agents for further tests.

Casuist BDI-Agent: A New Extended BDI Architecture with the Capability of Ethical Reasoning

NASA Astrophysics Data System (ADS)

Honarvar, Ali Reza; Ghasem-Aghaee, Nasser

Since the intelligent agent is developed to be cleverer, more complex, and yet uncontrollable, a number of problems have been recognized. The capability of agents to make moral decisions has become an important question, when intelligent agents have developed more autonomous and human-like. We propose Casuist BDI-Agent architecture which extends the power of BDI architecture. Casuist BDI-Agent architecture combines CBR method in AI and bottom up casuist approach in ethics in order to add capability of ethical reasoning to BDI-Agent.

Method of encapsulating polyaminopolycarboxylic acid chelating agents in liposomes

DOEpatents

Rahman, Yueh Erh

1977-11-10

A method is provided for transferring a polyaminopolycarboxylic acid chelating agent across a cellular membrane by encapsulating the charged chelating agent within liposomes, which liposomes will be taken up by the cells, thereby transferring the chelating agent across the cellular membrane. The chelating agent is encapsulated within liposomes by drying a lipid mixture to form a thin film and wetting the lipid film with a solution containing the chelating agent. Mixing then results in the formation of a suspension of liposomes encapsulating the chelating agent, which liposomes can then be separated.

Synergy of irofulven in combination with other DNA damaging agents: synergistic interaction with altretamine, alkylating, and platinum-derived agents in the MV522 lung tumor model.

PubMed

Kelner, Michael J; McMorris, Trevor C; Rojas, Rafael J; Estes, Leita A; Suthipinijtham, Pharnuk

2008-12-01

Irofulven (MGI 114, NSC 683863) is a semisynthetic derivative of illudin S, a natural product present in the Omphalotus illudins (Jack O'Lantern) mushroom. This novel agent produces DNA damage, that in contrast to other agents, is predominately ignored by the global genome repair pathway of the nucleotide excision repair (NER)(2) system. The aim of this study was to determine the antitumor activity of irofulven when administered in combination with 44 different DNA damaging agents, whose damage is in general detected and repaired by the genome repair pathway. The human lung carcinoma MV522 cell line and its corresponding xenograft model were used to evaluate the activity of irofulven in combination with different DNA damaging agents. Two main classes of DNA damaging agents, platinum-derived agents, and select bifunctional alkylating agents, demonstrated in vivo synergistic or super-additive interaction with irofulven. DNA helicase inhibiting agents also demonstrated synergy in vitro, but an enhanced interaction with irofulven could not be demonstrated in vivo. There was no detectable synergistic activity between irofulven and agents capable of inducing DNA cleavage or intercalating into DNA. These results indicate that the antitumor activity of irofulven is enhanced when combined with platinum-derived agents, altretamine, and select alkylating agents such as melphalan or chlorambucil. A common factor between these agents appears to be the production of intrastrand DNA crosslinks. The synergistic interaction between irofulven and other agents may stem from the nucleotide excision repair system being selectively overwhelmed at two distinct points in the pathway, resulting in prolonged stalling of transcription forks, and subsequent initiation of apoptosis.

Knowledge Management in Role Based Agents

NASA Astrophysics Data System (ADS)

Kır, Hüseyin; Ekinci, Erdem Eser; Dikenelli, Oguz

In multi-agent system literature, the role concept is getting increasingly researched to provide an abstraction to scope beliefs, norms, goals of agents and to shape relationships of the agents in the organization. In this research, we propose a knowledgebase architecture to increase applicability of roles in MAS domain by drawing inspiration from the self concept in the role theory of sociology. The proposed knowledgebase architecture has granulated structure that is dynamically organized according to the agent's identification in a social environment. Thanks to this dynamic structure, agents are enabled to work on consistent knowledge in spite of inevitable conflicts between roles and the agent. The knowledgebase architecture is also implemented and incorporated into the SEAGENT multi-agent system development framework.

Flexible, secure agent development framework

DOEpatents

Goldsmith,; Steven, Y [Rochester, MN

2009-04-07

While an agent generator is generating an intelligent agent, it can also evaluate the data processing platform on which it is executing, in order to assess a risk factor associated with operation of the agent generator on the data processing platform. The agent generator can retrieve from a location external to the data processing platform an open site that is configurable by the user, and load the open site into an agent substrate, thereby creating a development agent with code development capabilities. While an intelligent agent is executing a functional program on a data processing platform, it can also evaluate the data processing platform to assess a risk factor associated with performing the data processing function on the data processing platform.

Learning other agents` preferences in multiagent negotiation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bui, H.H.; Kieronska, D.; Venkatesh, S.

In multiagent systems, an agent does not usually have complete information about the preferences and decision making processes of other agents. This might prevent the agents from making coordinated choices, purely due to their ignorance of what others want. This paper describes the integration of a learning module into a communication-intensive negotiating agent architecture. The learning module gives the agents the ability to learn about other agents` preferences via past interactions. Over time, the agents can incrementally update their models of other agents` preferences and use them to make better coordinated decisions. Combining both communication and learning, as two complementmore » knowledge acquisition methods, helps to reduce the amount of communication needed on average, and is justified in situations where communication is computationally costly or simply not desirable (e.g. to preserve the individual privacy).« less

Hierarchically controlled remote preparation of an arbitrary single-qubit state by using a four-qubit |χ > entangled state

NASA Astrophysics Data System (ADS)

Ma, Peng-Cheng; Chen, Gui-Bin; Li, Xiao-Wei; Zhan, You-Bang

2018-05-01

In this paper, we present a scheme for Hierarchically controlled remote preparation of an arbitrary single-qubit state via a four-qubit |χ > state as the quantum channel. In this scheme, a sender wishes to help three agents to remotely prepare a quantum state, respectively. The three agents are divided into two grades, that is, an agent is in the upper grade and other two agents are in the lower grade. It is shown that the agent of the upper grade only needs the assistance of any one of the other two agents for recovering the sender's original state, while an agent of the lower grade needs the collaboration of all the other two agents. In other words, the agents of two grades have different authorities to recover sender's original state.

Method for tracking the location of mobile agents using stand-off detection technique

DOEpatents

Schmitt, Randal L [Tijeras, NM; Bender, Susan Fae Ann [Tijeras, NM; Rodacy, Philip J [Albuquerque, NM; Hargis, Jr., Philip J.; Johnson, Mark S [Albuquerque, NM

2006-12-26

A method for tracking the movement and position of mobile agents using light detection and ranging (LIDAR) as a stand-off optical detection technique. The positions of the agents are tracked by analyzing the time-history of a series of optical measurements made over the field of view of the optical system. This provides a (time+3-D) or (time+2-D) mapping of the location of the mobile agents. Repeated pulses of a laser beam impinge on a mobile agent, such as a bee, and are backscattered from the agent into a LIDAR detection system. Alternatively, the incident laser pulses excite fluorescence or phosphorescence from the agent, which is detected using a LIDAR system. Analysis of the spatial location of signals from the agents produced by repeated pulses generates a multidimensional map of agent location.

Agent-based method for distributed clustering of textual information

DOEpatents

Potok, Thomas E [Oak Ridge, TN; Reed, Joel W [Knoxville, TN; Elmore, Mark T [Oak Ridge, TN; Treadwell, Jim N [Louisville, TN

2010-09-28

A computer method and system for storing, retrieving and displaying information has a multiplexing agent (20) that calculates a new document vector (25) for a new document (21) to be added to the system and transmits the new document vector (25) to master cluster agents (22) and cluster agents (23) for evaluation. These agents (22, 23) perform the evaluation and return values upstream to the multiplexing agent (20) based on the similarity of the document to documents stored under their control. The multiplexing agent (20) then sends the document (21) and the document vector (25) to the master cluster agent (22), which then forwards it to a cluster agent (23) or creates a new cluster agent (23) to manage the document (21). The system also searches for stored documents according to a search query having at least one term and identifying the documents found in the search, and displays the documents in a clustering display (80) of similarity so as to indicate similarity of the documents to each other.

Agents in bioinformatics, computational and systems biology.

PubMed

Merelli, Emanuela; Armano, Giuliano; Cannata, Nicola; Corradini, Flavio; d'Inverno, Mark; Doms, Andreas; Lord, Phillip; Martin, Andrew; Milanesi, Luciano; Möller, Steffen; Schroeder, Michael; Luck, Michael

2007-01-01

The adoption of agent technologies and multi-agent systems constitutes an emerging area in bioinformatics. In this article, we report on the activity of the Working Group on Agents in Bioinformatics (BIOAGENTS) founded during the first AgentLink III Technical Forum meeting on the 2nd of July, 2004, in Rome. The meeting provided an opportunity for seeding collaborations between the agent and bioinformatics communities to develop a different (agent-based) approach of computational frameworks both for data analysis and management in bioinformatics and for systems modelling and simulation in computational and systems biology. The collaborations gave rise to applications and integrated tools that we summarize and discuss in context of the state of the art in this area. We investigate on future challenges and argue that the field should still be explored from many perspectives ranging from bio-conceptual languages for agent-based simulation, to the definition of bio-ontology-based declarative languages to be used by information agents, and to the adoption of agents for computational grids.

Method For Reactivating Solid Catalysts Used For Alklation Reactions

DOEpatents

Ginosar, Daniel M.; Thompson, David N.; Coates, Kyle; Zalewski, David J.; Fox, Robert V.

2005-05-03

A method for reactivating a solid alkylation catalyst is provided which can be performed within a reactor that contains the alkylation catalyst or outside the reactor. Effective catalyst reactivation is achieved whether the catalyst is completely deactivated or partially deactivated. A fluid reactivating agent is employed to dissolve catalyst fouling agents and also to react with such agents and carry away the reaction products. The deactivated catalyst is contacted with the fluid reactivating agent under pressure and temperature conditions such that the fluid reactivating agent is dense enough to effectively dissolve the fouling agents and any reaction products of the fouling agents and the reactivating agent. Useful pressures and temperatures for reactivation include near-critical, critical, and supercritical pressures and temperatures for the reactivating agent. The fluid reactivating agent can include, for example, a branched paraffin containing at least one tertiary carbon atom, or a compound that can be isomerized to a molecule containing at least one tertiary carbon atom.

Method for reactivating solid catalysts used in alkylation reactions

DOEpatents

Ginosar, Daniel M.; Thompson, David N.; Coates, Kyle; Zalewski, David J.; Fox, Robert V.

2003-06-17

A method for reactivating a solid alkylation catalyst is provided which can be performed within a reactor that contains the alkylation catalyst or outside the reactor. Effective catalyst reactivation is achieved whether the catalyst is completely deactivated or partially deactivated. A fluid reactivating agent is employed to dissolve catalyst fouling agents and also to react with such agents and carry away the reaction products. The deactivated catalyst is contacted with the fluid reactivating agent under pressure and temperature conditions such that the fluid reactivating agent is dense enough to effectively dissolve the fouling agents and any reaction products of the fouling agents and the reactivating agent. Useful pressures and temperatures for reactivation include near-critical, critical, and supercritical pressures and temperatures for the reactivating agent. The fluid reactivating agent can include, for example, a branched paraffin containing at least one tertiary carbon atom, or a compound that can be isomerized to a molecule containing at least one tertiary carbon atom.

Incorporating BDI Agents into Human-Agent Decision Making Research

NASA Astrophysics Data System (ADS)

Kamphorst, Bart; van Wissen, Arlette; Dignum, Virginia

Artificial agents, people, institutes and societies all have the ability to make decisions. Decision making as a research area therefore involves a broad spectrum of sciences, ranging from Artificial Intelligence to economics to psychology. The Colored Trails (CT) framework is designed to aid researchers in all fields in examining decision making processes. It is developed both to study interaction between multiple actors (humans or software agents) in a dynamic environment, and to study and model the decision making of these actors. However, agents in the current implementation of CT lack the explanatory power to help understand the reasoning processes involved in decision making. The BDI paradigm that has been proposed in the agent research area to describe rational agents, enables the specification of agents that reason in abstract concepts such as beliefs, goals, plans and events. In this paper, we present CTAPL: an extension to CT that allows BDI software agents that are written in the practical agent programming language 2APL to reason about and interact with a CT environment.

Spacecraft sanitation agent development

NASA Technical Reports Server (NTRS)

1972-01-01

The development of an effective sanitizing agent that is compatible with the spacecraft environment and the human occupant is discussed. Experimental results show that two sanitation agents must be used to satisfy mission requirements: one agent for personal hygiene and one for equipment maintenance. It was also recommended that a water rinse be used with the agents for best results, and that consideration be given to using the agents pressure packed or in aerosol formulations.

Drilling fluids and thinners therefor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Allison, G.M. III

1986-10-21

This patent describes an aqueous drilling fluid comprising water, finely divided solids and a first agent and a second agent. The first agent comprises a sulfoalkylated tannin containing no complexing heavy metal. The second agent comprises at least one at least partly water-soluble metal compound comprising tin. The weight ratio of the first agent to the second agent is in the range from about 100;1 to about 1:1.

Learning Sequences of Actions in Collectives of Autonomous Agents

NASA Technical Reports Server (NTRS)

Turner, Kagan; Agogino, Adrian K.; Wolpert, David H.; Clancy, Daniel (Technical Monitor)

2001-01-01

In this paper we focus on the problem of designing a collective of autonomous agents that individually learn sequences of actions such that the resultant sequence of joint actions achieves a predetermined global objective. We are particularly interested in instances of this problem where centralized control is either impossible or impractical. For single agent systems in similar domains, machine learning methods (e.g., reinforcement learners) have been successfully used. However, applying such solutions directly to multi-agent systems often proves problematic, as agents may work at cross-purposes, or have difficulty in evaluating their contribution to achievement of the global objective, or both. Accordingly, the crucial design step in multiagent systems centers on determining the private objectives of each agent so that as the agents strive for those objectives, the system reaches a good global solution. In this work we consider a version of this problem involving multiple autonomous agents in a grid world. We use concepts from collective intelligence to design goals for the agents that are 'aligned' with the global goal, and are 'learnable' in that agents can readily see how their behavior affects their utility. We show that reinforcement learning agents using those goals outperform both 'natural' extensions of single agent algorithms and global reinforcement, learning solutions based on 'team games'.

Adaptivity in Agent-Based Routing for Data Networks

NASA Technical Reports Server (NTRS)

Wolpert, David H.; Kirshner, Sergey; Merz, Chris J.; Turner, Kagan

2000-01-01

Adaptivity, both of the individual agents and of the interaction structure among the agents, seems indispensable for scaling up multi-agent systems (MAS s) in noisy environments. One important consideration in designing adaptive agents is choosing their action spaces to be as amenable as possible to machine learning techniques, especially to reinforcement learning (RL) techniques. One important way to have the interaction structure connecting agents itself be adaptive is to have the intentions and/or actions of the agents be in the input spaces of the other agents, much as in Stackelberg games. We consider both kinds of adaptivity in the design of a MAS to control network packet routing. We demonstrate on the OPNET event-driven network simulator the perhaps surprising fact that simply changing the action space of the agents to be better suited to RL can result in very large improvements in their potential performance: at their best settings, our learning-amenable router agents achieve throughputs up to three and one half times better than that of the standard Bellman-Ford routing algorithm, even when the Bellman-Ford protocol traffic is maintained. We then demonstrate that much of that potential improvement can be realized by having the agents learn their settings when the agent interaction structure is itself adaptive.

Agent tracking: a psycho-historical theory of the identification of living and social agents.

PubMed

Bullot, Nicolas J

To explain agent-identification behaviours, universalist theories in the biological and cognitive sciences have posited mental mechanisms thought to be universal to all humans, such as agent detection and face recognition mechanisms. These universalist theories have paid little attention to how particular sociocultural or historical contexts interact with the psychobiological processes of agent-identification. In contrast to universalist theories, contextualist theories appeal to particular historical and sociocultural contexts for explaining agent-identification. Contextualist theories tend to adopt idiographic methods aimed at recording the heterogeneity of human behaviours across history, space, and cultures. Defenders of the universalist approach tend to criticise idiographic methods because such methods can lead to relativism or may lack generality. To overcome explanatory limitations of proposals that adopt either universalist or contextualist approaches in isolation, I propose a philosophical model that integrates contributions from both traditions: the psycho-historical theory of agent-identification. This theory investigates how the tracking processes that humans use for identifying agents interact with the unique socio-historical contexts that support agent-identification practices. In integrating hypotheses about the history of agents with psychological and epistemological principles regarding agent-identification, the theory can generate novel hypotheses regarding the distinction between recognition-based, heuristic-based, and explanation-based agent-identification.

Efficient Evaluation Functions for Multi-Rover Systems

NASA Technical Reports Server (NTRS)

Agogino, Adrian; Tumer, Kagan

2004-01-01

Evolutionary computation can be a powerful tool in cresting a control policy for a single agent receiving local continuous input. This paper extends single-agent evolutionary computation to multi-agent systems, where a collection of agents strives to maximize a global fitness evaluation function that rates the performance of the entire system. This problem is solved in a distributed manner, where each agent evolves its own population of neural networks that are used as the control policies for the agent. Each agent evolves its population using its own agent-specific fitness evaluation function. We propose to create these agent-specific evaluation functions using the theory of collectives to avoid the coordination problem where each agent evolves a population that maximizes its own fitness function, yet the system has a whole achieves low values of the global fitness function. Instead we will ensure that each fitness evaluation function is both "aligned" with the global evaluation function and is "learnable," i.e., the agents can readily see how their behavior affects their evaluation function. We then show how these agent-specific evaluation functions outperform global evaluation methods by up to 600% in a domain where a set of rovers attempt to maximize the amount of information observed while navigating through a simulated environment.

Integrin Targeted MR Imaging

PubMed Central

Tan, Mingqian; Lu, Zheng-Rong

2011-01-01

Magnetic resonance imaging (MRI) is a powerful medical diagnostic imaging modality for integrin targeted imaging, which uses the magnetic resonance of tissue water protons to display tissue anatomic structures with high spatial resolution. Contrast agents are often used in MRI to highlight specific regions of the body and make them easier to visualize. There are four main classes of MRI contrast agents based on their different contrast mechanisms, including T1, T2, chemical exchange saturation transfer (CEST) agents, and heteronuclear contrast agents. Integrins are an important family of heterodimeric transmembrane glycoproteins that function as mediators of cell-cell and cell-extracellular matrix interactions. The overexpressed integrins can be used as the molecular targets for designing suitable integrin targeted contrast agents for MR molecular imaging. Integrin targeted contrast agent includes a targeting agent specific to a target integrin, a paramagnetic agent and a linker connecting the targeting agent with the paramagnetic agent. Proper selection of targeting agents is critical for targeted MRI contrast agents to effectively bind to integrins for in vivo imaging. An ideal integrin targeted MR contrast agent should be non-toxic, provide strong contrast enhancement at the target sites and can be completely excreted from the body after MR imaging. An overview of integrin targeted MR contrast agents based on small molecular and macromolecular Gd(III) complexes, lipid nanoparticles and superparamagnetic nanoparticles is provided for MR molecular imaging. By using proper delivery systems for loading sufficient Gd(III) chelates or superparamagnetic nanoparticles, effective molecular imaging of integrins with MRI has been demonstrated in animal models. PMID:21547154

Use of positive oral contrast agents in abdominopelvic computed tomography for blunt abdominal injury: meta-analysis and systematic review.

PubMed

Lee, Chau Hung; Haaland, Benjamin; Earnest, Arul; Tan, Cher Heng

2013-09-01

To determine whether positive oral contrast agents improve accuracy of abdominopelvic CT compared with no, neutral or negative oral contrast agent. Literature was searched for studies evaluating the diagnostic performance of abdominopelvic CT with positive oral contrast agents against imaging with no, neutral or negative oral contrast agent. Meta-analysis reviewed studies correlating CT findings of blunt abdominal injury with positive and without oral contrast agents against surgical, autopsy or clinical outcome allowing derivation of pooled sensitivity and specificity. Systematic review was performed on studies with common design and reference standard. Thirty-two studies were divided into two groups. Group 1 comprised 15 studies comparing CT with positive and without oral contrast agents. Meta-analysis of five studies from group 1 provided no difference in sensitivity or specificity between CT with positive or without oral contrast agents. Group 2 comprised 17 studies comparing CT with positive and neutral or negative oral contrast agents. Systematic review of 12 studies from group 2 indicated that neutral or negative oral contrasts were as effective as positive oral contrast agents for bowel visualisation. There is no difference in accuracy between CT performed with positive oral contrast agents or with no, neutral or negative oral contrast agent. • There is no difference in the accuracy of CT with or without oral contrast agent. • There is no difference in the accuracy of CT with Gastrografin or water. • Omission of oral contrast, utilising neutral or negative oral contrast agent saves time, costs and decreases risk of aspiration.

Autonomous Mission Operations for Sensor Webs

NASA Astrophysics Data System (ADS)

Underbrink, A.; Witt, K.; Stanley, J.; Mandl, D.

2008-12-01

We present interim results of a 2005 ROSES AIST project entitled, "Using Intelligent Agents to Form a Sensor Web for Autonomous Mission Operations", or SWAMO. The goal of the SWAMO project is to shift the control of spacecraft missions from a ground-based, centrally controlled architecture to a collaborative, distributed set of intelligent agents. The network of intelligent agents intends to reduce management requirements by utilizing model-based system prediction and autonomic model/agent collaboration. SWAMO agents are distributed throughout the Sensor Web environment, which may include multiple spacecraft, aircraft, ground systems, and ocean systems, as well as manned operations centers. The agents monitor and manage sensor platforms, Earth sensing systems, and Earth sensing models and processes. The SWAMO agents form a Sensor Web of agents via peer-to-peer coordination. Some of the intelligent agents are mobile and able to traverse between on-orbit and ground-based systems. Other agents in the network are responsible for encapsulating system models to perform prediction of future behavior of the modeled subsystems and components to which they are assigned. The software agents use semantic web technologies to enable improved information sharing among the operational entities of the Sensor Web. The semantics include ontological conceptualizations of the Sensor Web environment, plus conceptualizations of the SWAMO agents themselves. By conceptualizations of the agents, we mean knowledge of their state, operational capabilities, current operational capacities, Web Service search and discovery results, agent collaboration rules, etc. The need for ontological conceptualizations over the agents is to enable autonomous and autonomic operations of the Sensor Web. The SWAMO ontology enables automated decision making and responses to the dynamic Sensor Web environment and to end user science requests. The current ontology is compatible with Open Geospatial Consortium (OGC) Sensor Web Enablement (SWE) Sensor Model Language (SensorML) concepts and structures. The agents are currently deployed on the U.S. Naval Academy MidSTAR-1 satellite and are actively managing the power subsystem on-orbit without the need for human intervention.

Using Synchronous Boolean Networks to Model Several Phenomena of Collective Behavior

PubMed Central

Kochemazov, Stepan; Semenov, Alexander

2014-01-01

In this paper, we propose an approach for modeling and analysis of a number of phenomena of collective behavior. By collectives we mean multi-agent systems that transition from one state to another at discrete moments of time. The behavior of a member of a collective (agent) is called conforming if the opinion of this agent at current time moment conforms to the opinion of some other agents at the previous time moment. We presume that at each moment of time every agent makes a decision by choosing from the set (where 1-decision corresponds to action and 0-decision corresponds to inaction). In our approach we model collective behavior with synchronous Boolean networks. We presume that in a network there can be agents that act at every moment of time. Such agents are called instigators. Also there can be agents that never act. Such agents are called loyalists. Agents that are neither instigators nor loyalists are called simple agents. We study two combinatorial problems. The first problem is to find a disposition of instigators that in several time moments transforms a network from a state where the majority of simple agents are inactive to a state with the majority of active agents. The second problem is to find a disposition of loyalists that returns the network to a state with the majority of inactive agents. Similar problems are studied for networks in which simple agents demonstrate the contrary to conforming behavior that we call anticonforming. We obtained several theoretical results regarding the behavior of collectives of agents with conforming or anticonforming behavior. In computational experiments we solved the described problems for randomly generated networks with several hundred vertices. We reduced corresponding combinatorial problems to the Boolean satisfiability problem (SAT) and used modern SAT solvers to solve the instances obtained. PMID:25526612

Riot Control Agents

MedlinePlus

... Submit What's this? Submit Button Facts About Riot Control Agents Interim document Recommend on Facebook Tweet Share Compartir What riot control agents are Riot control agents (sometimes referred to ...

Agility: Agent - Ility Architecture

DTIC Science & Technology

2002-10-01

existing and emerging standards (e.g., distributed objects, email, web, search engines , XML, Java, Jini). Three agent system components resulted from...agents and other Internet resources and operate over the web (AgentGram), a yellow pages service that uses Internet search engines to locate XML ads for agents and other Internet resources (WebTrader).

42 CFR 73.11 - Security.

Code of Federal Regulations, 2010 CFR

2010-10-01

... select agent or toxin against unauthorized access, theft, loss, or release. (b) The security plan must be... activities, loss or theft of select agents or toxins, release of select agents or toxins, or alteration of... of select agents or toxins, (iv) Any release of a select agent or toxin, and (v) Any sign that...

9 CFR 121.11 - Security.

Code of Federal Regulations, 2010 CFR

2010-01-01

... the select agent or toxin against unauthorized access, theft, loss, or release. (b) The security plan... activities, loss or theft of select agents or toxins, release of select agents or toxins, or alteration of... of select agents or toxins; (iv) Any release of a select agent or toxin; and (v) Any sign that...

Preparing Change Agents for Change Agent Roles.

ERIC Educational Resources Information Center

Sedlacek, James R.

Seventy-seven Spanish- and Portuguese-speaking agricultural change agents from developing Central and South American countries responded to a questionnaire which sought perceptions of the roles in which the change agents felt they were involved and the roles for which they felt they were being trained. The agents were participating in training…

77 FR 71702 - Possession, Use, and Transfer of Select Agents and Toxins; Biennial Review

Federal Register 2010, 2011, 2012, 2013, 2014

2012-12-04

... of Select Agents and Toxins; Biennial Review AGENCY: Centers for Disease Control and Prevention (CDC... designated certain select agents and toxins as Tier 1 agents. DATES: Effective Date: Effective December 4, 2012. FOR FURTHER INFORMATION CONTACT: Robbin Weyant, Director, Division of Select Agents and Toxins...

Using Physiological Measures to Assess the Effects of Animated Pedagogical Agents in Multimedia Instruction

ERIC Educational Resources Information Center

Romero-Hall, Enilda; Watson, Ginger; Papelis, Yiannnis

2014-01-01

To examine the visual attention, emotional responses, learning, perceptions and attitudes of learners interacting with an animated pedagogical agent, this study compared a multimedia learning environment with an emotionally-expressive animated pedagogical agent, with a non-expressive animated pedagogical agent, and without an agent. Visual…

Intelligent Agents for the Digital Battlefield

DTIC Science & Technology

1998-11-01

specific outcome of our long term research will be the development of a collaborative agent technology system, CATS , that will provide the underlying...software infrastructure needed to build large, heterogeneous, distributed agent applications. CATS will provide a software environment through which multiple...intelligent agents may interact with other agents, both human and computational. In addition, CATS will contain a number of intelligent agent components that will be useful for a wide variety of applications.

Agent planning in AgScala

NASA Astrophysics Data System (ADS)

Tošić, Saša; Mitrović, Dejan; Ivanović, Mirjana

2013-10-01

Agent-oriented programming languages are designed to simplify the development of software agents, especially those that exhibit complex, intelligent behavior. This paper presents recent improvements of AgScala, an agent-oriented programming language based on Scala. AgScala includes declarative constructs for managing beliefs, actions and goals of intelligent agents. Combined with object-oriented and functional programming paradigms offered by Scala, it aims to be an efficient framework for developing both purely reactive, and more complex, deliberate agents. Instead of the Prolog back-end used initially, the new version of AgScala relies on Agent Planning Package, a more advanced system for automated planning and reasoning.

Mining Temporal Patterns to Improve Agents Behavior: Two Case Studies

NASA Astrophysics Data System (ADS)

Fournier-Viger, Philippe; Nkambou, Roger; Faghihi, Usef; Nguifo, Engelbert Mephu

We propose two mechanisms for agent learning based on the idea of mining temporal patterns from agent behavior. The first one consists of extracting temporal patterns from the perceived behavior of other agents accomplishing a task, to learn the task. The second learning mechanism consists in extracting temporal patterns from an agent's own behavior. In this case, the agent then reuses patterns that brought self-satisfaction. In both cases, no assumption is made on how the observed agents' behavior is internally generated. A case study with a real application is presented to illustrate each learning mechanism.

Learning to cooperate in solving the traveling salesman problem.

PubMed

Qi, Dehu; Sun, Ron

2005-01-01

A cooperative team of agents may perform many tasks better than single agents. The question is how cooperation among self-interested agents should be achieved. It is important that, while we encourage cooperation among agents in a team, we maintain autonomy of individual agents as much as possible, so as to maintain flexibility and generality. This paper presents an approach based on bidding utilizing reinforcement values acquired through reinforcement learning. We tested and analyzed this approach and demonstrated that a team indeed performed better than the best single agent as well as the average of single agents.

Epoxy foams using multiple resins and curing agents

DOEpatents

Russick, Edward M.; Rand, Peter B.

2000-01-01

An epoxy foam comprising a plurality of resins, a plurality of curing agents, at least one blowing agent, at least one surfactant and optionally at least one filler and the process for making. Preferred is an epoxy foam comprising two resins of different reactivities, two curing agents, a blowing agent, a surfactant, and a filler. According to the present invention, an epoxy foam is prepared with tailorable reactivity, exotherm, and pore size by a process of admixing a plurality of resins with a plurality of curing agents, a surfactant and blowing agent, whereby a foamable mixture is formed and heating said foamable mixture at a temperature greater than the boiling temperature of the blowing agent whereby said mixture is foamed and cured.

A Novel Network Attack Audit System based on Multi-Agent Technology

NASA Astrophysics Data System (ADS)

Jianping, Wang; Min, Chen; Xianwen, Wu

A network attack audit system which includes network attack audit Agent, host audit Agent and management control center audit Agent is proposed. And the improved multi-agent technology is carried out in the network attack audit Agent which has achieved satisfactory audit results. The audit system in terms of network attack is just in-depth, and with the function improvement of network attack audit Agent, different attack will be better analyzed and audit. In addition, the management control center Agent should manage and analyze audit results from AA (or HA) and audit data on time. And the history files of network packets and host log data should also be audit to find deeper violations that cannot be found in real time.

Formal Consistency Verification of Deliberative Agents with Respect to Communication Protocols

NASA Technical Reports Server (NTRS)

Ramirez, Jaime; deAntonio, Angelica

2004-01-01

The aim of this paper is to show a method that is able to detect inconsistencies in the reasoning carried out by a deliberative agent. The agent is supposed to be provided with a hybrid Knowledge Base expressed in a language called CCR-2, based on production rules and hierarchies of frames, which permits the representation of non-monotonic reasoning, uncertain reasoning and arithmetic constraints in the rules. The method can give a specification of the scenarios in which the agent would deduce an inconsistency. We define a scenario to be a description of the initial agent s state (in the agent life cycle), a deductive tree of rule firings, and a partially ordered set of messages and/or stimuli that the agent must receive from other agents and/or the environment. Moreover, the method will make sure that the scenarios will be valid w.r.t. the communication protocols in which the agent is involved.

Children's understanding of the costs and rewards underlying rational action.

PubMed

Jara-Ettinger, Julian; Gweon, Hyowon; Tenenbaum, Joshua B; Schulz, Laura E

2015-07-01

Humans explain and predict other agents' behavior using mental state concepts, such as beliefs and desires. Computational and developmental evidence suggest that such inferences are enabled by a principle of rational action: the expectation that agents act efficiently, within situational constraints, to achieve their goals. Here we propose that the expectation of rational action is instantiated by a naïve utility calculus sensitive to both agent-constant and agent-specific aspects of costs and rewards associated with actions. In four experiments, we show that, given an agent's choices, children (range: 5-6 year olds; N=96) can infer unobservable aspects of costs (differences in agents' competence) from information about subjective differences in rewards (differences in agents' preferences) and vice versa. Moreover, children can design informative experiments on both objects and agents to infer unobservable constraints on agents' actions. Copyright © 2015 Elsevier B.V. All rights reserved.

Relay tracking control for second-order multi-agent systems with damaged agents.

PubMed

Dong, Lijing; Li, Jing; Liu, Qin

2017-11-01

This paper investigates a situation where smart agents capable of sensory and mobility are deployed to monitor a designated area. A preset number of agents start tracking when a target intrudes this area. Some of the tracking agents are possible to be out of order over the tracking course. Thus, we propose a cooperative relay tracking strategy to ensure the successful tracking with existence of damaged agents. Relay means that, when a tracking agent quits tracking due to malfunction, one of the near deployed agents replaces it to continue the tracking task. This results in jump of tracking errors and dynamic switching of topology of the multi-agent system. Switched system technique is employed to solve this specific problem. Finally, the effectiveness of proposed tracking strategy and validity of the theoretical results are verified by conducting a numerical simulation. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Evaluation of new antiemetic agents and definition of antineoplastic agent emetogenicity--an update.

PubMed

Grunberg, Steven M; Osoba, David; Hesketh, Paul J; Gralla, Richard J; Borjeson, Sussanne; Rapoport, Bernardo L; du Bois, Andreas; Tonato, Maurizio

2005-02-01

Development of effective antiemetic therapy depends upon an understanding of both the antiemetic agents and the emetogenic challenges these agents are designed to address. New potential antiemetic agents should be studied in an orderly manner, proceeding from phase I to phase II open-label trials and then to randomized double-blind phase III trials comparing new agents and regimens to best standard therapy. Use of placebos in place of antiemetic therapy against highly or moderately emetogenic chemotherapy is unacceptable. Nausea and vomiting should be evaluated separately and for both the acute and delayed periods. Defining the emetogenicity of new antineoplastic agents is a challenge, since such data are often not reliably recorded during early drug development. A four-level classification system is proposed for emetogenicity of intravenous antineoplastic agents. A separate four-level classification system for emetogenicity of oral antineoplastic agents, which are often given over an extended period of time, is also proposed.

A Measure of Real-Time Intelligence

NASA Astrophysics Data System (ADS)

Gavane, Vaibhav

2013-03-01

We propose a new measure of intelligence for general reinforcement learning agents, based on the notion that an agent's environment can change at any step of execution of the agent. That is, an agent is considered to be interacting with its environment in real-time. In this sense, the resulting intelligence measure is more general than the universal intelligence measure (Legg and Hutter, 2007) and the anytime universal intelligence test (Hernández-Orallo and Dowe, 2010). A major advantage of the measure is that an agent's computational complexity is factored into the measure in a natural manner. We show that there exist agents with intelligence arbitrarily close to the theoretical maximum, and that the intelligence of agents depends on their parallel processing capability. We thus believe that the measure can provide a better evaluation of agents and guidance for building practical agents with high intelligence.

Propagation of the state change induced by external forces in local interactions

NASA Astrophysics Data System (ADS)

Lu, Jianjun; Tokinaga, Shozo

2016-10-01

This paper analyses the propagation of the state changes of agents that are induced by external forces applied to a plane. In addition, we propose two models for the behavior of the agents placed on a lattice plane, both of which are affected by local interactions. We first assume that agents are allowed to move to another site to maximise their satisfaction. Second, we utilise a model in which the agents choose activities on each site. The results show that the migration (activity) patterns of agents in both models achieve stability without any external forces. However, when we apply an impulsive external force to the state of the agents, we then observe the propagation of the changes in the agents' states. Using simulation studies, we show the conditions for the propagation of the state changes of the agents. We also show the propagation of the state changes of the agents allocated in scale-free networks and discuss the estimation of the agents' decisions in real state changes. Finally, we discuss the estimation of the agents' decisions in real state temporal changes using economic and social data from Japan and the United States.

Exchanging large data object in multi-agent systems

NASA Astrophysics Data System (ADS)

Al-Yaseen, Wathiq Laftah; Othman, Zulaiha Ali; Nazri, Mohd Zakree Ahmad

2016-08-01

One of the Business Intelligent solutions that is currently in use is the Multi-Agent System (MAS). Communication is one of the most important elements in MAS, especially for exchanging large low level data between distributed agents (physically). The Agent Communication Language in JADE has been offered as a secure method for sending data, whereby the data is defined as an object. However, the object cannot be used to send data to another agent in a different location. Therefore, the aim of this paper was to propose a method for the exchange of large low level data as an object by creating a proxy agent known as a Delivery Agent, which temporarily imitates the Receiver Agent. The results showed that the proposed method is able to send large-sized data. The experiments were conducted using 16 datasets ranging from 100,000 to 7 million instances. However, for the proposed method, the RAM and the CPU machine had to be slightly increased for the Receiver Agent, but the latency time was not significantly different compared to the use of the Java Socket method (non-agent and less secure). With such results, it was concluded that the proposed method can be used to securely send large data between agents.

Application of Toxic Chinese Medicine in Chinese Pharmacopoeia

NASA Astrophysics Data System (ADS)

Zhao, Hui; Feng, Yu; Mao, Mingsan

2018-01-01

Objective: Explore the application characteristics of proprietary Chinese medicine prescriptions containing toxic herbs in pharmacopoeia. Methods: In this paper, according to the clinical application of pharmacopoeia proprietary Chinese medicine is divided into table agent, Qushu agent, diarrhea agent, heat agent, Wen Li agent, cough and asthma agents, resuscitation agent, Gutian agent, Fuzheng agent, Anshen agent, hemostatic agent, The traditional Chinese medicine prescription and the clinical application of the Chinese herbal medicine containing the toxic Chinese medicine were analyzed and sorted out., Summed up the compatibility of toxic herbs and application characteristics. Results: Toxic Chinese herbal medicine in the cure of traditional Chinese medicine to play a long-standing role, through the overall thinking, dialectical thinking, and thinking of toxic Chinese medicine in the analysis of Chinese medicine that [2], toxic Chinese medicine in the application of proprietary Chinese medicine can not lack. Conclusion: Pharmacopoeia included proprietary Chinese medicine not only in the clinical treatment of good, but also the application of its toxic traditional Chinese medicine and its understanding of the enrichment of the toxic characteristics of traditional Chinese medicine and treatment-related disease pathology between the points of contact for patients with clinical applications Based on and theoretical guidance of Chinese medicine [3].

Unifying Temporal and Structural Credit Assignment Problems

NASA Technical Reports Server (NTRS)

Agogino, Adrian K.; Tumer, Kagan

2004-01-01

Single-agent reinforcement learners in time-extended domains and multi-agent systems share a common dilemma known as the credit assignment problem. Multi-agent systems have the structural credit assignment problem of determining the contributions of a particular agent to a common task. Instead, time-extended single-agent systems have the temporal credit assignment problem of determining the contribution of a particular action to the quality of the full sequence of actions. Traditionally these two problems are considered different and are handled in separate ways. In this article we show how these two forms of the credit assignment problem are equivalent. In this unified frame-work, a single-agent Markov decision process can be broken down into a single-time-step multi-agent process. Furthermore we show that Monte-Carlo estimation or Q-learning (depending on whether the values of resulting actions in the episode are known at the time of learning) are equivalent to different agent utility functions in a multi-agent system. This equivalence shows how an often neglected issue in multi-agent systems is equivalent to a well-known deficiency in multi-time-step learning and lays the basis for solving time-extended multi-agent problems, where both credit assignment problems are present.

Infectious causes of reproductive disorders in cattle.

PubMed

Yoo, Han Sang

2010-01-01

The incidences of reproductive disorders in bovine are increasing over years. This scenario is further aggravating due to more emphasis on selection and rearing of animal for specific commercial purposes which compromises livestock reproduction. Reproductive disorders like infertility and abortions in cattle are major problems in the bovine industry. The reproductive disorders might be caused by several different agents such as physical agents, chemical agents, biological agents, etc. Also, the causative agent and pathogenesis of reproductive disorders are influenced by various factors including environmental factor. The exact causes may not be evident and are often complicated with multiple causative agents. Thus, there is a need for multi-faceted approach to understand correlation of various factors with reproductive performance. Of the agents, infectious biological agents are significant cause of reproductive disorder and are of high priority in the bovine industry. These factors are not only related to the prosperity of bovine industry but are also important from public health point of view because of their zoonotic potentials. Several infectious agents like bacterial, viral, protozoon, chlamydial and fungal agents are known to have direct impact on reproductive health of cattle. These diseases can be arranged and discussed in different groups based on the causative agents.

Toward Shared Working Space of Human and Robotic Agents Through Dipole Flow Field for Dependable Path Planning.

PubMed

Trinh, Lan Anh; Ekström, Mikael; Cürüklü, Baran

2018-01-01

Recent industrial developments in autonomous systems, or agents, which assume that humans and the agents share the same space or even work in close proximity, open for new challenges in robotics, especially in motion planning and control. In these settings, the control system should be able to provide these agents a reliable path following control when they are working in a group or in collaboration with one or several humans in complex and dynamic environments. In such scenarios, these agents are not only moving to reach their goals, i.e., locations, they are also aware of the movements of other entities to find a collision-free path. Thus, this paper proposes a dependable, i.e., safe, reliable and effective, path planning algorithm for a group of agents that share their working space with humans. Firstly, the method employs the Theta * algorithm to initialize the paths from a starting point to a goal for a set of agents. As Theta * algorithm is computationally heavy, it only reruns when there is a significant change of the environment. To deal with the movements of the agents, a static flow field along the configured path is defined. This field is used by the agents to navigate and reach their goals even if the planned trajectories are changed. Secondly, a dipole field is calculated to avoid the collision of agents with other agents and human subjects. In this approach, each agent is assumed to be a source of a magnetic dipole field in which the magnetic moment is aligned with the moving direction of the agent. The magnetic dipole-dipole interactions between these agents generate repulsive forces to help them to avoid collision. The effectiveness of the proposed approach has been evaluated with extensive simulations. The results show that the static flow field is able to drive agents to the goals with a small number of requirements to update the path of agents. Meanwhile, the dipole flow field plays an important role to prevent collisions. The combination of these two fields results in a safe path planning algorithm, with a deterministic outcome, to navigate agents to their desired goals.

Blaptica dubia as sentinels for exposure to chemical warfare agents - a pilot study.

PubMed

Worek, Franz; Seeger, Thomas; Neumaier, Katharina; Wille, Timo; Thiermann, Horst

2016-11-16

The increased interest of terrorist groups in toxic chemicals and chemical warfare agents presents a continuing threat to our societies. Early warning and detection is a key component for effective countermeasures against such deadly agents. Presently available and near term solutions have a number of major drawbacks, e.g. lack of automated, remote warning and detection of primarily low volatile chemical warfare agents. An alternative approach is the use of animals as sentinels for exposure to toxic chemicals. To overcome disadvantages of vertebrates the present pilot study was initiated to investigate the suitability of South American cockroaches (Blaptica dubia) as warning system for exposure to chemical warfare nerve and blister agents. Initial in vitro experiments with nerve agents showed an increasing inhibitory potency in the order tabun - cyclosarin - sarin - soman - VX of cockroach cholinesterase. Exposure of cockroaches to chemical warfare agents resulted in clearly visible and reproducible reactions, the onset being dependent on the agent and dose. With nerve agents the onset was related to the volatility of the agents. The blister agent lewisite induced signs largely comparable to those of nerve agents while sulfur mustard exposed animals exhibited a different sequence of events. In conclusion, this first pilot study indicates that Blaptica dubia could serve as a warning system to exposure of chemical warfare agents. A cockroach-based system will not detect or identify a particular chemical warfare agent but could trigger further actions, e.g. specific detection and increased protective status. By designing appropriate boxes with (IR) motion sensors and remote control (IR) camera automated off-site warning systems could be realized. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Carboxylate-containing chelating agent interactions with amorphous chromium hydroxide: Adsorption and dissolution

NASA Astrophysics Data System (ADS)

Carbonaro, Richard F.; Gray, Benjamin N.; Whitehead, Charles F.; Stone, Alan T.

2008-07-01

Anthropogenic chelating agents and biological chelating agents produced by indigenous organisms may dissolve Cr III (hydr)oxides in soils and sediments. The resulting dissolved Cr III-chelating agent complexes are more readily transported through porous media, thereby spreading contamination. With this work, we examine chelating agent-assisted dissolution of amorphous chromium hydroxide (ACH) by the (amino)carboxylate chelating agents iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), tricarballylic acid (TCA), citric acid (CIT), ethylenediaminetetraacetic acid (EDTA), trans-1,2-cyclohexanediaminetetraacetic acid (CDTA), and trimethylenediaminetetraacetic acid (TMDTA). The extent of chelating agent adsorption onto ACH increased quickly over the first few hours, and then increased more gradually until a constant extent was attained. The extent of chelating agent adsorption versus pH followed "ligand-like" behavior. All chelating agents with the exception of TCA and IDA effectively dissolved significant amounts of ACH within 10 days from pH 4.0 to 9.4. IDA dissolved ACH below pH 6.5 and above pH 7.5. Rates of ACH dissolution normalized to the extent of chelating agent adsorption were pH dependent. IDA, NTA, CIT, and CDTA exhibited an increase in normalized dissolution rate with decreasing pH. EDTA and TMDTA exhibited a maximum in normalized dissolution rate near pH 8.5. Use of acetic acid as a pH buffer in experiments decreased the extent of chelating agent adsorption for IDA, NTA, and CIT but increased normalized rates of chelating agent-assisted dissolution for all chelating agents except EDTA. The results from this study provide the necessary information to calculate the extents and time scales of ACH dissolution in the presence of (amino)carboxylate chelating agents.

Symposium on Toxic Substance Control: Decontamination, April 22 - 24, 1980, Columbus, Ohio.

DTIC Science & Technology

1981-06-01

standard decontaminants is used. TABLE 1. Standard Chemical Decontaminants Decontaminant Agents Used On STB Blister and nerve agents DS-2 All chemical... agents M258 Kit Sodium Hydroxide, Ethanol, G-Series nerve agents Phenol, Water Chloramine B, ZnCI2, Blister ana V-Series Ethanol, Water nerve agents A...is a point source alarm that actively samples ambient air and reacts to low concentrations of nerve agents . The M-8 alarm detector also detects several

Safe motion planning for mobile agents: A model of reactive planning for multiple mobile agents

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fujimura, Kikuo.

1990-01-01

The problem of motion planning for multiple mobile agents is studied. Each planning agent independently plans its own action based on its map which contains a limited information about the environment. In an environment where more than one mobile agent interacts, the motions of the robots are uncertain and dynamic. A model for reactive agents is described and simulation results are presented to show their behavior patterns. 18 refs., 2 figs.

Limonene and tetrahydrofurfurly alcohol cleaning agent

DOEpatents

Bohnert, George W.; Carter, Richard D.; Hand, Thomas E.; Powers, Michael T.

1997-10-21

The present invention is a tetrahydrofurfuryl alcohol and limonene cleaning agent and method for formulating and/or using the cleaning agent. This cleaning agent effectively removes both polar and nonpolar contaminants from various electrical and mechanical parts and is readily used without surfactants, thereby reducing the need for additional cleaning operations. The cleaning agent is warm water rinsable without the use of surfactants. The cleaning agent can be azeotropic, enhancing ease of use in cleaning operations and ease of recycling.

Limonene and tetrahydrofurfuryl alcohol cleaning agent

DOEpatents

Bohnert, G.W.; Carter, R.D.; Hand, T.E.; Powers, M.T.

1997-10-21

The present invention is a tetrahydrofurfuryl alcohol and limonene cleaning agent and method for formulating and/or using the cleaning agent. This cleaning agent effectively removes both polar and nonpolar contaminants from various electrical and mechanical parts and is readily used without surfactants, thereby reducing the need for additional cleaning operations. The cleaning agent is warm water rinsable without the use of surfactants. The cleaning agent can be azeotropic, enhancing ease of use in cleaning operations and ease of recycling.

Benzamide Derivatives as Protective Agents against the Action of Xenotoxic Agents on Human Cells.

DTIC Science & Technology

1984-05-31

4D-AlI45 396 BENZAMIDE DERIVATIVES AS PROTECTIVE AGENTS AGAINST THE I/i ACTION OF XENOTOXI..(U) OHIO STATE UNIV RESEARCH I FOUNDATION COLUMBUS G E...AS PROTECTIVE AGENTS AGAINST THE ACTION OF XENOTOXIC AGENTS ON HUMAN CELLS CD George E. Milo * Department of Physiological Chemistry and...TITLE (and Subtitle) S. .YPE OF REPORT & PERIOD COVERED Benzamide Derivatives as Protective Agents Annual Scientific Report 5 Against the Action of

Home Energy Management System - VOLTTRON Integration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zandi, Helia

In most Home Energy Management Systems (HEMS) available in the market, different devices running different communication protocols cannot interact with each other and exchange information. As a result of this integration, the information about different devices running different communication protocol can be accessible by other agents and devices running on VOLTTRON platform. The integration process can be used by any HEMS available in the market regardless of the programming language they use. If the existing HEMS provides an Application Programming Interface (API) based on the RESTFul architecture, that API can be used for integration. Our candidate HEMS in this projectmore » is home-assistant (Hass). An agent is implemented which can communicate with the Hass API and receives information about the devices loaded on the API. The agent publishes the information it receives on the VOLTTRON message bus so other agents can have access to this information. On the other side, for each type of devices, an agent is implemented such as Climate Agent, Lock Agent, Switch Agent, Light Agent, etc. Each of these agents is subscribed to the messages published on the message bus about their associated devices. These agents can also change the status of the devices by sending appropriate service calls to the API. Other agents and services on the platform can also access this information and coordinate their decision-making process based on this information.« less

Adaptive Neuro-Fuzzy Determination of the Effect of Experimental Parameters on Vehicle Agent Speed Relative to Vehicle Intruder.

PubMed

Shamshirband, Shahaboddin; Banjanovic-Mehmedovic, Lejla; Bosankic, Ivan; Kasapovic, Suad; Abdul Wahab, Ainuddin Wahid Bin

2016-01-01

Intelligent Transportation Systems rely on understanding, predicting and affecting the interactions between vehicles. The goal of this paper is to choose a small subset from the larger set so that the resulting regression model is simple, yet have good predictive ability for Vehicle agent speed relative to Vehicle intruder. The method of ANFIS (adaptive neuro fuzzy inference system) was applied to the data resulting from these measurements. The ANFIS process for variable selection was implemented in order to detect the predominant variables affecting the prediction of agent speed relative to intruder. This process includes several ways to discover a subset of the total set of recorded parameters, showing good predictive capability. The ANFIS network was used to perform a variable search. Then, it was used to determine how 9 parameters (Intruder Front sensors active (boolean), Intruder Rear sensors active (boolean), Agent Front sensors active (boolean), Agent Rear sensors active (boolean), RSSI signal intensity/strength (integer), Elapsed time (in seconds), Distance between Agent and Intruder (m), Angle of Agent relative to Intruder (angle between vehicles °), Altitude difference between Agent and Intruder (m)) influence prediction of agent speed relative to intruder. The results indicated that distance between Vehicle agent and Vehicle intruder (m) and angle of Vehicle agent relative to Vehicle Intruder (angle between vehicles °) is the most influential parameters to Vehicle agent speed relative to Vehicle intruder.

The kuru infectious agent is a unique geographic isolate distinct from Creutzfeldt–Jakob disease and scrapie agents

PubMed Central

Manuelidis, Laura; Chakrabarty, Trisha; Miyazawa, Kohtaro; Nduom, Nana-Aba; Emmerling, Kaitlin

2009-01-01

Human sporadic Creutzfeldt–Jakob disease (sCJD), endemic sheep scrapie, and epidemic bovine spongiform encephalopathy (BSE) are caused by a related group of infectious agents. The new U.K. BSE agent spread to many species, including humans, and clarifying the origin, specificity, virulence, and diversity of these agents is critical, particularly because infected humans do not develop disease for many years. As with viruses, transmissible spongiform encephalopathy (TSE) agents can adapt to new species and become more virulent yet maintain fundamentally unique and stable identities. To make agent differences manifest, one must keep the host genotype constant. Many TSE agents have revealed their independent identities in normal mice. We transmitted primate kuru, a TSE once epidemic in New Guinea, to mice expressing normal and ≈8-fold higher levels of murine prion protein (PrP). High levels of murine PrP did not prevent infection but instead shortened incubation time, as would be expected for a viral receptor. Sporadic CJD and BSE agents and representative scrapie agents were clearly different from kuru in incubation time, brain neuropathology, and lymphoreticular involvement. Many TSE agents can infect monotypic cultured GT1 cells, and unlike sporadic CJD isolates, kuru rapidly and stably infected these cells. The geographic independence of the kuru agent provides additional reasons to explore causal environmental pathogens in these infectious neurodegenerative diseases. PMID:19633190

Can Moral Hazard Be Resolved by Common-Knowledge in S4n-Knowledge?

NASA Astrophysics Data System (ADS)

Matsuhisa, Takashi

This article investigates the relationship between common-knowledge and agreement in multi-agent system, and to apply the agreement result by common-knowledge to the principal-agent model under non-partition information. We treat the two problems: (1) how we capture the fact that the agents agree on an event or they get consensus on it from epistemic point of view, and (2) how the agreement theorem will be able to make progress to settle a moral hazard problem in the principal-agents model under non-partition information. We shall propose a solution program for the moral hazard in the principal-agents model under non-partition information by common-knowledge. Let us start that the agents have the knowledge structure induced from a reflexive and transitive relation associated with the multi-modal logic S4n. Each agent obtains the membership value of an event under his/her private information, so he/she considers the event as fuzzy set. Specifically consider the situation that the agents commonly know all membership values of the other agents. In this circumstance we shall show the agreement theorem that consensus on the membership values among all agents can still be guaranteed. Furthermore, under certain assumptions we shall show that the moral hazard can be resolved in the principal-agent model when all the expected marginal costs are common-knowledge among the principal and agents.

Mother ship and physical agents collaboration

NASA Astrophysics Data System (ADS)

Young, Stuart H.; Budulas, Peter P.; Emmerman, Philip J.

1999-07-01

This paper discusses ongoing research at the U.S. Army Research Laboratory that investigates the feasibility of developing a collaboration architecture between small physical agents and a mother ship. This incudes the distribution of planning, perception, mobility, processing and communications requirements between the mother ship and the agents. Small physical agents of the future will be virtually everywhere on the battlefield of the 21st century. A mother ship that is coupled to a team of small collaborating physical agents (conducting tasks such as Reconnaissance, Surveillance, and Target Acquisition (RSTA); logistics; sentry; and communications relay) will be used to build a completely effective and mission capable intelligent system. The mother ship must have long-range mobility to deploy the small, highly maneuverable agents that will operate in urban environments and more localized areas, and act as a logistics base for the smaller agents. The mother ship also establishes a robust communications network between the agents and is the primary information disseminating and receiving point to the external world. Because of its global knowledge and processing power, the mother ship does the high-level control and planning for the collaborative physical agents. This high level control and interaction between the mother ship and its agents (including inter agent collaboration) will be software agent architecture based. The mother ship incorporates multi-resolution battlefield visualization and analysis technology, which aids in mission planning and sensor fusion.

Cooperation and Coordination Between Fuzzy Reinforcement Learning Agents in Continuous State Partially Observable Markov Decision Processes

NASA Technical Reports Server (NTRS)

Berenji, Hamid R.; Vengerov, David

1999-01-01

Successful operations of future multi-agent intelligent systems require efficient cooperation schemes between agents sharing learning experiences. We consider a pseudo-realistic world in which one or more opportunities appear and disappear in random locations. Agents use fuzzy reinforcement learning to learn which opportunities are most worthy of pursuing based on their promise rewards, expected lifetimes, path lengths and expected path costs. We show that this world is partially observable because the history of an agent influences the distribution of its future states. We consider a cooperation mechanism in which agents share experience by using and-updating one joint behavior policy. We also implement a coordination mechanism for allocating opportunities to different agents in the same world. Our results demonstrate that K cooperative agents each learning in a separate world over N time steps outperform K independent agents each learning in a separate world over K*N time steps, with this result becoming more pronounced as the degree of partial observability in the environment increases. We also show that cooperation between agents learning in the same world decreases performance with respect to independent agents. Since cooperation reduces diversity between agents, we conclude that diversity is a key parameter in the trade off between maximizing utility from cooperation when diversity is low and maximizing utility from competitive coordination when diversity is high.

Multiagent data warehousing and multiagent data mining for cerebrum/cerebellum modeling

NASA Astrophysics Data System (ADS)

Zhang, Wen-Ran

2002-03-01

An algorithm named Neighbor-Miner is outlined for multiagent data warehousing and multiagent data mining. The algorithm is defined in an evolving dynamic environment with autonomous or semiautonomous agents. Instead of mining frequent itemsets from customer transactions, the new algorithm discovers new agents and mining agent associations in first-order logic from agent attributes and actions. While the Apriori algorithm uses frequency as a priory threshold, the new algorithm uses agent similarity as priory knowledge. The concept of agent similarity leads to the notions of agent cuboid, orthogonal multiagent data warehousing (MADWH), and multiagent data mining (MADM). Based on agent similarities and action similarities, Neighbor-Miner is proposed and illustrated in a MADWH/MADM approach to cerebrum/cerebellum modeling. It is shown that (1) semiautonomous neurofuzzy agents can be identified for uniped locomotion and gymnastic training based on attribute relevance analysis; (2) new agents can be discovered and agent cuboids can be dynamically constructed in an orthogonal MADWH, which resembles an evolving cerebrum/cerebellum system; and (3) dynamic motion laws can be discovered as association rules in first order logic. Although examples in legged robot gymnastics are used to illustrate the basic ideas, the new approach is generally suitable for a broad category of data mining tasks where knowledge can be discovered collectively by a set of agents from a geographically or geometrically distributed but relevant environment, especially in scientific and engineering data environments.

Remote Agent Demonstration

NASA Technical Reports Server (NTRS)

Dorais, Gregory A.; Kurien, James; Rajan, Kanna

1999-01-01

We describe the computer demonstration of the Remote Agent Experiment (RAX). The Remote Agent is a high-level, model-based, autonomous control agent being validated on the NASA Deep Space 1 spacecraft.

76 FR 62412 - Agency Forms Undergoing Paperwork Reduction Act Review

Federal Register 2010, 2011, 2012, 2013, 2014

2011-10-07

... for Registration, (2) Request to Transfer Select Agent or Toxin, (3) Report of Theft, Loss, or Release..., or Release of Select Agent and Toxin, (4) Report of Identification of Select Agent or Toxin. There... Release of Select Agent or Toxin; (4) Report of Identification of Select Agent or Toxin; and (5) Request...

27 CFR 555.220 - Table of separation distances of ammonium nitrate and blasting agents from explosives or blasting...

Code of Federal Regulations, 2010 CFR

2010-04-01

... distances of ammonium nitrate and blasting agents from explosives or blasting agents. 555.220 Section 555... ammonium nitrate and blasting agents from explosives or blasting agents. Table: Department of Defense... Not over Minimum separation distance of acceptor from donor when barricaded (ft.) Ammonium nitrate...

27 CFR 555.220 - Table of separation distances of ammonium nitrate and blasting agents from explosives or blasting...

Code of Federal Regulations, 2011 CFR

2011-04-01

... distances of ammonium nitrate and blasting agents from explosives or blasting agents. 555.220 Section 555... ammonium nitrate and blasting agents from explosives or blasting agents. Table: Department of Defense... Not over Minimum separation distance of acceptor from donor when barricaded (ft.) Ammonium nitrate...

27 CFR 555.220 - Table of separation distances of ammonium nitrate and blasting agents from explosives or blasting...

Code of Federal Regulations, 2012 CFR

2012-04-01

... distances of ammonium nitrate and blasting agents from explosives or blasting agents. 555.220 Section 555... ammonium nitrate and blasting agents from explosives or blasting agents. Table: Department of Defense... Not over Minimum separation distance of acceptor from donor when barricaded (ft.) Ammonium nitrate...

27 CFR 555.220 - Table of separation distances of ammonium nitrate and blasting agents from explosives or blasting...

Code of Federal Regulations, 2013 CFR

2013-04-01

... distances of ammonium nitrate and blasting agents from explosives or blasting agents. 555.220 Section 555... ammonium nitrate and blasting agents from explosives or blasting agents. Table: Department of Defense... Not over Minimum separation distance of acceptor from donor when barricaded (ft.) Ammonium nitrate...

27 CFR 555.220 - Table of separation distances of ammonium nitrate and blasting agents from explosives or blasting...

Code of Federal Regulations, 2014 CFR

2014-04-01

... distances of ammonium nitrate and blasting agents from explosives or blasting agents. 555.220 Section 555... ammonium nitrate and blasting agents from explosives or blasting agents. Table: Department of Defense... Not over Minimum separation distance of acceptor from donor when barricaded (ft.) Ammonium nitrate...

The Effect of Pacing on Learners' Perceptions of Pedagogical Agents

ERIC Educational Resources Information Center

Schroeder, Noah L.; Craig, Scotty D.

2017-01-01

This study examined the influence of three levels of learner control on learners' perceptions when learning with a pedagogical agent. Pedagogical agents have shown promise for improving learning and connections with learning materials within video-based instruction, and research has shown that agent design choices can influence how agents are…

29 CFR 1926.905 - Loading of explosives or blasting agents.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 29 Labor 8 2010-07-01 2010-07-01 false Loading of explosives or blasting agents. 1926.905 Section... Explosives § 1926.905 Loading of explosives or blasting agents. (a) Procedures that permit safe and efficient... have contained explosives or blasting agents. (g) No explosives or blasting agents shall be left...

78 FR 77471 - Prospective Grant of Exclusive License for: Convection Enhanced Delivery of a Therapeutic Agent...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-12-23

...-toxic macromolecular MRI contrast agents such as chelated Gd(III). These macromolecular imaging agents... Exclusive License for: Convection Enhanced Delivery of a Therapeutic Agent With a Surrogate Tracer for... Enhanced Delivery of Therapeutic Agents'', U.S. Provisional Patent Application 60/413,673 (filed September...

17 CFR 240.17Ad-10 - Prompt posting of certificate detail to master securityholder files, maintenance of accurate...

Code of Federal Regulations, 2014 CFR

2014-04-01

... between co-transfer agents and recordkeeping transfer agents, maintenance of current control book...-transfer agents and recordkeeping transfer agents, maintenance of current control book, retention of certificate detail and “buy-in” of physical over-issuance. (a)(1) Every recordkeeping transfer agent shall...

EMOTION RECOGNITION OF VIRTUAL AGENTS FACIAL EXPRESSIONS: THE EFFECTS OF AGE AND EMOTION INTENSITY

PubMed Central

Beer, Jenay M.; Fisk, Arthur D.; Rogers, Wendy A.

2014-01-01

People make determinations about the social characteristics of an agent (e.g., robot or virtual agent) by interpreting social cues displayed by the agent, such as facial expressions. Although a considerable amount of research has been conducted investigating age-related differences in emotion recognition of human faces (e.g., Sullivan, & Ruffman, 2004), the effect of age on emotion identification of virtual agent facial expressions has been largely unexplored. Age-related differences in emotion recognition of facial expressions are an important factor to consider in the design of agents that may assist older adults in a recreational or healthcare setting. The purpose of the current research was to investigate whether age-related differences in facial emotion recognition can extend to emotion-expressive virtual agents. Younger and older adults performed a recognition task with a virtual agent expressing six basic emotions. Larger age-related differences were expected for virtual agents displaying negative emotions, such as anger, sadness, and fear. In fact, the results indicated that older adults showed a decrease in emotion recognition accuracy for a virtual agent's emotions of anger, fear, and happiness. PMID:25552896

Learning comunication strategies for distributed artificial intelligence

NASA Astrophysics Data System (ADS)

Kinney, Michael; Tsatsoulis, Costas

1992-08-01

We present a methodology that allows collections of intelligent system to automatically learn communication strategies, so that they can exchange information and coordinate their problem solving activity. In our methodology communication between agents is determined by the agents themselves, which consider the progress of their individual problem solving activities compared to the communication needs of their surrounding agents. Through learning, communication lines between agents might be established or disconnected, communication frequencies modified, and the system can also react to dynamic changes in the environment that might force agents to cease to exist or to be added. We have established dynamic, quantitative measures of the usefulness of a fact, the cost of a fact, the work load of an agent, and the selfishness of an agent (a measure indicating an agent's preference between transmitting information versus performing individual problem solving), and use these values to adapt the communication between intelligent agents. In this paper we present the theoretical foundations of our work together with experimental results and performance statistics of networks of agents involved in cooperative problem solving activities.

[Alkylating agents].

PubMed

Pourquier, Philippe

2011-11-01

With the approval of mechlorethamine by the FDA in 1949 for the treatment of hematologic malignancies, alkylating agents are the oldest class of anticancer agents. Even though their clinical use is far beyond the use of new targeted therapies, they still occupy a major place in specific indications and sometimes represent the unique option for the treatment of refractory diseases. Here, we are reviewing the major classes of alkylating agents and their mechanism of action, with a particular emphasis for the new generations of alkylating agents. As for most of the chemotherapeutic agents used in the clinic, these compounds are derived from natural sources. With a complex but original mechanism of action, they represent new interesting alternatives for the clinicians, especially for tumors that are resistant to conventional DNA damaging agents. We also briefly describe the different strategies that have been or are currently developed to potentiate the use of classical alkylating agents, especially the inhibition of pathways that are involved in the repair of DNA lesions induced by these agents. In this line, the development of PARP inhibitors is a striking example of the recent regain of interest towards the "old" alkylating agents.

Influences of Agents with a Self-Reputation Awareness Component in an Evolutionary Spatial IPD Game

PubMed Central

Huang, Chung-Yuan; Lee, Chun-Liang

2014-01-01

Iterated prisoner’s dilemma (IPD) researchers have shown that strong positive reputations plus an efficient reputation evaluation system encourages both sides to pursue long-term collaboration and to avoid falling into mutual defection cycles. In agent-based environments with reliable reputation rating systems, agents interested in maximizing their private interests must show concern for other agents as well as their own self-reputations–an important capability that standard IPD game agents lack. Here we present a novel learning agent model possessing self-reputation awareness. Agents in our proposed model are capable of evaluating self-behaviors based on a mix of public and private interest considerations, and of testing various solutions aimed at meeting social standards. Simulation results indicate multiple outcomes from the addition of a small percentage of self-reputation awareness agents: faster cooperation, faster movement toward stability in an agent society, a higher level of public interest in the agent society, the resolution of common conflicts between public and private interests, and a lower potential for rational individual behavior to transform into irrational group behavior. PMID:24945966

Distributed Evaluation Functions for Fault Tolerant Multi-Rover Systems

NASA Technical Reports Server (NTRS)

Agogino, Adrian; Turner, Kagan

2005-01-01

The ability to evolve fault tolerant control strategies for large collections of agents is critical to the successful application of evolutionary strategies to domains where failures are common. Furthermore, while evolutionary algorithms have been highly successful in discovering single-agent control strategies, extending such algorithms to multiagent domains has proven to be difficult. In this paper we present a method for shaping evaluation functions for agents that provide control strategies that both are tolerant to different types of failures and lead to coordinated behavior in a multi-agent setting. This method neither relies of a centralized strategy (susceptible to single point of failures) nor a distributed strategy where each agent uses a system wide evaluation function (severe credit assignment problem). In a multi-rover problem, we show that agents using our agent-specific evaluation perform up to 500% better than agents using the system evaluation. In addition we show that agents are still able to maintain a high level of performance when up to 60% of the agents fail due to actuator, communication or controller faults.

Biological Agents

MedlinePlus

... E-Tools Safety and Health Topics / Biological Agents Biological Agents This page requires that javascript be enabled ... 202) 693-2300 if additional assistance is required. Biological Agents Menu Overview In Focus: Ebola Frederick A. ...

Persuasive Conversational Agent with Persuasion Tactics

NASA Astrophysics Data System (ADS)

Narita, Tatsuya; Kitamura, Yasuhiko

Persuasive conversational agents persuade people to change their attitudes or behaviors through conversation, and are expected to be applied as virtual sales clerks in e-shopping sites. As an approach to create such an agent, we have developed a learning agent with the Wizard of Oz method in which a person called Wizard talks to the user pretending to be the agent. The agent observes the conversations between the Wizard and the user, and learns how to persuade people. In this method, the Wizard has to reply to most of the user's inputs at the beginning, but the burden gradually falls because the agent learns how to reply as the conversation model grows.

Agent Architectures for Compliance

NASA Astrophysics Data System (ADS)

Burgemeestre, Brigitte; Hulstijn, Joris; Tan, Yao-Hua

A Normative Multi-Agent System consists of autonomous agents who must comply with social norms. Different kinds of norms make different assumptions about the cognitive architecture of the agents. For example, a principle-based norm assumes that agents can reflect upon the consequences of their actions; a rule-based formulation only assumes that agents can avoid violations. In this paper we present several cognitive agent architectures for self-monitoring and compliance. We show how different assumptions about the cognitive architecture lead to different information needs when assessing compliance. The approach is validated with a case study of horizontal monitoring, an approach to corporate tax auditing recently introduced by the Dutch Customs and Tax Authority.

Use of topical hemostatic agents in gynecologic surgery.

PubMed

Wysham, Weiya Z; Roque, Dario R; Soper, John T

2014-09-01

Sutures, hemoclips, and electrocautery are the primary mechanisms used to achieve hemostasis during gynecologic surgery, but in situations in which these are inadequate or not feasible, an array of hemostatic agents are available to help achieve hemostasis. These agents include physical agents such as cellulose, collagen, or gelatin products as well as biologic agents such as thrombin and fibrin products. Limited data are available on many of these agents, although their use is increasing, sometimes at high costs. In gynecologic surgery, hemostatic agents are likely most effective when used in areas of oozing or slow bleeding and as an adjunct to conventional surgical methods of hemostasis.

Knowledge focus via software agents

NASA Astrophysics Data System (ADS)

Henager, Donald E.

2001-09-01

The essence of military Command and Control (C2) is making knowledge intensive decisions in a limited amount of time using uncertain, incorrect, or outdated information. It is essential to provide tools to decision-makers that provide: * Management of friendly forces by treating the "friendly resources as a system". * Rapid assessment of effects of military actions againt the "enemy as a system". * Assessment of how an enemy should, can, and could react to friendly military activities. Software agents in the form of mission agents, target agents, maintenance agents, and logistics agents can meet this information challenge. The role of each agent is to know all the details about its assigned mission, target, maintenance, or logistics entity. The Mission Agent would fight for mission resources based on the mission priority and analyze the effect that a proposed mission's results would have on the enemy. The Target Agent (TA) communicates with other targets to determine its role in the system of targets. A system of TAs would be able to inform a planner or analyst of the status of a system of targets, the effect of that status, adn the effect of attacks on that system. The system of TAs would also be able to analyze possible enemy reactions to attack by determining ways to minimize the effect of attack, such as rerouting traffic or using deception. The Maintenance Agent would scheudle maintenance events and notify the maintenance unit. The Logistics Agent would manage shipment and delivery of supplies to maintain appropriate levels of weapons, fuel and spare parts. The central idea underlying this case of software agents is knowledge focus. Software agents are createad automatically to focus their attention on individual real-world entities (e.g., missions, targets) and view the world from that entities perspective. The agent autonomously monitors the entity, identifies problems/opportunities, formulates solutions, and informs the decision-maker. The agent must be able to communicate to receive and disseminate information and provide the decision-maker with assistance via focused knowledge. THe agent must also be able to monitor the state of its own environment and make decisions necessary to carry out its delegated tasks. Agents bring three elements to the C2 domain that offer to improve decision-making. First, they provide higher-quality feedback and provide it more often. In doing so, the feedback loop becomes nearly continuous, reducing or eliminating delays in situation updates to decision-makers. Working with the most current information possible improves the control process, thus enabling effects based operations. Second, the agents accept delegation of actions and perform those actions following an established process. Agents' consistent actions reduce the variability of human input and stabilize the control process. Third, through the delegation of actions, agents ensure 100 percent consideration of plan details.

Preapproval and postapproval availability of published comparative efficacy research on biological agents.

PubMed

Thomas, Rachel Hutchins; Freeman, Maisha Kelly; Hughes, Peter J

2013-07-15

Preapproval and postapproval availability of published comparative efficacy studies on biological agents approved between 2000 and 2010 was investigated. Approval packages published on the Food and Drug Administration (FDA) website were examined for all biological agents approved between 2000 and 2010 to determine if comparative efficacy studies were available at the time of FDA approval. The availability of comparative efficacy studies published subsequent to approval was determined by searching PubMed for randomized, active-controlled experimental or observational study designs that measured efficacy as the primary endpoint and were relevant to the original FDA-approved indication. From 2000 to 2010, 107 biological agents were approved by FDA. Of the biological agents with alternative treatments, 54.6% had comparative efficacy data available at the time of approval. Although standard-reviewed biological agents were more likely to have comparative efficacy trials included in the FDA approval packages than priority-reviewed biological agents, statistically significant differences are unlikely. Subsequent to approval, 58.1% of biological agents had at least one published comparative efficacy trial, representing a 3.5% absolute increase in the availability of comparative efficacy studies since the time of approval. Vaccines and biological agents in the hematologic diseases, oncology, and miscellaneous diseases classes had fewer published postapproval comparative efficacy studies per agent compared with the overall group of biological agents. Nearly half of all biological agents approved for marketing between 2000 and 2010 lacked publicly accessible, active-controlled efficacy studies at the time of drug approval; a slightly greater proportion of biological agents had comparative efficacy data published subsequent to their approval.

Molecular Imaging of Tumors Using a Quantitative T1 Mapping Technique via Magnetic Resonance Imaging

PubMed Central

Herrmann, Kelsey; Johansen, Mette L.; Craig, Sonya E.; Vincent, Jason; Howell, Michael; Gao, Ying; Lu, Lan; Erokwu, Bernadette; Agnes, Richard S.; Lu, Zheng-Rong; Pokorski, Jonathan K.; Basilion, James; Gulani, Vikas; Griswold, Mark; Flask, Chris; Brady-Kalnay, Susann M.

2015-01-01

Magnetic resonance imaging (MRI) of glioblastoma multiforme (GBM) with molecular imaging agents would allow for the specific localization of brain tumors. Prior studies using T1-weighted MR imaging demonstrated that the SBK2-Tris-(Gd-DOTA)3 molecular imaging agent labeled heterotopic xenograft models of brain tumors more intensely than non-specific contrast agents using conventional T1-weighted imaging techniques. In this study, we used a dynamic quantitative T1 mapping strategy to more objectively compare intra-tumoral retention of the SBK2-Tris-(Gd-DOTA)3 agent over time in comparison to non-targeted control agents. Our results demonstrate that the targeted SBK2-Tris-(Gd-DOTA)3 agent, a scrambled-Tris-(Gd-DOTA)3 control agent, and the non-specific clinical contrast agent Optimark™ all enhanced flank tumors of human glioma cells with similar maximal changes on T1 mapping. However, the retention of the agents differs. The non-specific agents show significant recovery within 20 min by an increase in T1 while the specific agent SBK2-Tris-(Gd-DOTA)3 is retained in the tumors and shows little recovery over 60 min. The retention effect is demonstrated by percent change in T1 values and slope calculations as well as by calculations of gadolinium concentration in tumor compared to muscle. Quantitative T1 mapping demonstrates the superior binding and retention in tumors of the SBK2-Tris-(Gd-DOTA)3 agent over time compared to the non-specific contrast agent currently in clinical use. PMID:26435847

The balance between adaptation to catalysts and competition radius shapes the total wealth, time variability and inequality

NASA Astrophysics Data System (ADS)

Davidovich, Hadar; Louzoun, Yoram

2013-05-01

The globalization of modern markets has led to the emergence of competition between producers in ever growing distances. This opens the interesting question in population dynamics of the effect of long-range competition. We here study a model of non-local competition to test the effect of the competition radius on the wealth distribution, using the framework of a stochastic birth-death process, with non-local interactions. We show that this model leads to non-trivial dynamics that can have implications in other domains of physics. Competition is studied in the context of the catalyst induced growth of autocatalytic agents, representing the growth of capital in the presence of investment opportunities. These agents are competing with all other agents in a given radius on growth possibilities. We show that a large scale competition leads to an extreme localization of the agents, where typically a single aggregate of agents can survive within a given competition radius. The survival of these aggregates is determined by the diffusion rates of the agents and the catalysts. For high and low agent diffusion rates, the agent population is always annihilated, while for intermediate diffusion rates, a finite agent population persists. Increasing the catalyst diffusion rate always leads to a decrease in the average agent population density. The extreme localization of the agents leads to the emergence of intermittent fluctuations, when a large aggregate of agents disappear. As the competition radius increases, so does the average agent density and its spatial variance as well as the volatility.

Cooperation in Human-Agent Systems to Support Resilience: A Microworld Experiment.

PubMed

Chiou, Erin K; Lee, John D

2016-09-01

This study uses a dyadic approach to understand human-agent cooperation and system resilience. Increasingly capable technology fundamentally changes human-machine relationships. Rather than reliance on or compliance with more or less reliable automation, we investigate interaction strategies with more or less cooperative agents. A joint-task microworld scenario was developed to explore the effects of agent cooperation on participant cooperation and system resilience. To assess the effects of agent cooperation on participant cooperation, 36 people coordinated with a more or less cooperative agent by requesting resources and responding to requests for resources in a dynamic task environment. Another 36 people were recruited to assess effects following a perturbation in their own hospital. Experiment 1 shows people reciprocated the cooperative behaviors of the agents; a low-cooperation agent led to less effective interactions and less resource sharing, whereas a high-cooperation agent led to more effective interactions and greater resource sharing. Experiment 2 shows that an initial fast-tempo perturbation undermined proactive cooperation-people tended to not request resources. However, the initial fast tempo had little effect on reactive cooperation-people tended to accept resource requests according to cooperation level. This study complements the supervisory control perspective of human-automation interaction by considering interdependence and cooperation rather than the more common focus on reliability and reliance. The cooperativeness of automated agents can influence the cooperativeness of human agents. Design and evaluation for resilience in teams involving increasingly autonomous agents should consider the cooperative behaviors of these agents. © 2016, Human Factors and Ergonomics Society.

Replication and spread of CJD, kuru and scrapie agents in vivo and in cell culture

PubMed Central

Miyazawa, Kohtaro; Emmerling, Kaitlin

2011-01-01

Transmissible Spongiform Encephalopathy (TSE) agents are defined by their virulence for particular species, their spread in the population, their incubation time to cause disease, and their neuropathological sequelae. Murine adapted human agents, including sporadic CJD (sCJD), New Guinea kuru, and Japanese CJD agents, display particularly distinct incubation times and maximal infectious brain titers. They also induce agent-specific patterns of neurodegeneration. When these TSE agents are transmitted to cultured hypothalamic GT1 cells they maintain their unique identities. Nevertheless, the human kuru (kCJD) and Japanese FU-CJD agents, as well as the sheep 22L and 263K scrapie agents display doubling times that are 8× to 33× faster in cells than in brain, indicating release from complex innate immune responses. These data are most consistent with a foreign viral structure, rather than an infectious form of host prion protein (PrP-res). Profound agent-specific inhibitory effects are also apparent in GT1 cells, and maximal titer plateau in kCJD and FU-CJD differed by 1,000-fold in a cell-based assay. Remarkably, the lower titer kCJD agent rapidly induced de novo PrP-res in GT1 cells, whereas the high titer FU-CJD agent replicated silently for multiple passages. Although PrP-res is often considered to be toxic, PrP-res instead may be part of a primal defense and/or clearance mechanism against TSE environmental agents. Limited spread of particular TSE agents through nanotubes and cell-to-cell contacts probably underlies the long peripheral phase of human CJD. PMID:21527829

A Medical Center Network for Optimized Lung Cancer Biospecimen Banking

DTIC Science & Technology

2013-10-01

Carcinoma Stage IIB N N .149 1 8 .132 1 8 .092 1 No - Quit Smoking 50 AR Agent Orange , Nuclear weapons, Second-hand smoke Agent Orange , Nuclear weapons...Smoking 30 None Agent Orange , Asbestos, Second-hand smoke Agent Orange , Asbestos, Second-hand smoke S0159 Squamous Cell Carcinoma Stage IIB Y N...2.560 100 80 25 6 7 0.670 4 4 0.370 1 No - Quit Smoking 30 NV Agent Orange , Asbestos, Nuclear weapons, Second- hand smoke Agent Orange , Asbestos

Limonene and tetrahydrofurfuryl alcohol cleaning agent

DOEpatents

Bohnert, George W.; Carter, Richard D.; Hand, Thomas E.; Powers, Michael T.

1996-05-07

The present invention is a tetrahydrofurfuryl alcohol and limonene or terpineol cleaning agent and method for formulating and/or using the cleaning agent. This cleaning agent effectively removes both polar and nonpolar contaminants from various electrical and mechanical parts and is readily used without surfactants, thereby reducing the need for additional cleaning operations. The cleaning agent is warm water rinsable without the use of surfactants. The cleaning agent can be azeotropic, enhancing ease of use in cleaning operations and ease of recycling.

The Resurrection of Malthus: space as the final escape from the law of diminishing returns

NASA Astrophysics Data System (ADS)

Sommers, J.; Beldavs, V.

2017-09-01

If there is a self-sustaining space economy, which is the goal of the International Lunar Decade, then it is a subject of economic analysis. The immediate challenge of space economics then is to conceptually demonstrate how a space economy could emerge and work where markets do not exist and few human agents may be involved, in fact where human agents may transact with either human agents or robotic agents or robotic agents may transact with other robotic agents.

Quicker Q-Learning in Multi-Agent Systems

NASA Technical Reports Server (NTRS)

Agogino, Adrian K.; Tumer, Kagan

2005-01-01

Multi-agent learning in Markov Decisions Problems is challenging because of the presence ot two credit assignment problems: 1) How to credit an action taken at time step t for rewards received at t' greater than t; and 2) How to credit an action taken by agent i considering the system reward is a function of the actions of all the agents. The first credit assignment problem is typically addressed with temporal difference methods such as Q-learning OK TD(lambda) The second credit assi,onment problem is typically addressed either by hand-crafting reward functions that assign proper credit to an agent, or by making certain independence assumptions about an agent's state-space and reward function. To address both credit assignment problems simultaneously, we propose the Q Updates with Immediate Counterfactual Rewards-learning (QUICR-learning) designed to improve both the convergence properties and performance of Q-learning in large multi-agent problems. Instead of assuming that an agent s value function can be made independent of other agents, this method suppresses the impact of other agents using counterfactual rewards. Results on multi-agent grid-world problems over multiple topologies show that QUICR-learning can achieve up to thirty fold improvements in performance over both conventional and local Q-learning in the largest tested systems.

An agent-based method for simulating porous fluid-saturated structures with indistinguishable components

NASA Astrophysics Data System (ADS)

Kashani, Jamal; Pettet, Graeme John; Gu, YuanTong; Zhang, Lihai; Oloyede, Adekunle

2017-10-01

Single-phase porous materials contain multiple components that intermingle up to the ultramicroscopic level. Although the structures of the porous materials have been simulated with agent-based methods, the results of the available methods continue to provide patterns of distinguishable solid and fluid agents which do not represent materials with indistinguishable phases. This paper introduces a new agent (hybrid agent) and category of rules (intra-agent rule) that can be used to create emergent structures that would more accurately represent single-phase structures and materials. The novel hybrid agent carries the characteristics of system's elements and it is capable of changing within itself, while also responding to its neighbours as they also change. As an example, the hybrid agent under one-dimensional cellular automata formalism in a two-dimensional domain is used to generate patterns that demonstrate the striking morphological and characteristic similarities with the porous saturated single-phase structures where each agent of the ;structure; carries semi-permeability property and consists of both fluid and solid in space and at all times. We conclude that the ability of the hybrid agent to change locally provides an enhanced protocol to simulate complex porous structures such as biological tissues which could facilitate models for agent-based techniques and numerical methods.

Sustainable Society Formed by Unselfish Agents

NASA Astrophysics Data System (ADS)

Kikuchi, Toshiko

It has been pointed out that if the social configuration of the three relations (market, communal and obligatory relations) is not balanced, a market based society as a total system fails. Using multi-agent simulations, this paper shows that a sustainable society is formed when all three relations are integrated and function respectively. When agent trades are based on the market mechanism (i.e., agents act in their own interest and thus only market relations exist), weak agents who cannot perform transactions die. If a compulsory tax is imposed to enable all weak agents to survive (i.e., obligatory relations exist), then the fiscal deficit increases. On the other hand, if agents who have excess income undertake the unselfish action of distributing their surplus to the weak agents (i.e., communal relations exist), then trade volume increases. It is shown that the existence of unselfish agents is necessary for the realization of a sustainable society. However, the survival of all agents is difficult in a communal society. In an artificial society, for all agents survive and fiscal balance to be maintained, all three social relations need to be fully integrated. These results show that adjusting the balance of the three social relations well lead to the realization of a sustainable society.

An embodiment effect in computer-based learning with animated pedagogical agents.

PubMed

Mayer, Richard E; DaPra, C Scott

2012-09-01

How do social cues such as gesturing, facial expression, eye gaze, and human-like movement affect multimedia learning with onscreen agents? To help address this question, students were asked to twice view a 4-min narrated presentation on how solar cells work in which the screen showed an animated pedagogical agent standing to the left of 11 successive slides. Across three experiments, learners performed better on a transfer test when a human-voiced agent displayed human-like gestures, facial expression, eye gaze, and body movement than when the agent did not, yielding an embodiment effect. In Experiment 2 the embodiment effect was found when the agent spoke in a human voice but not in a machine voice. In Experiment 3, the embodiment effect was found both when students were told the onscreen agent was consistent with their choice of agent characteristics and when inconsistent. Students who viewed a highly embodied agent also rated the social attributes of the agent more positively than did students who viewed a nongesturing agent. The results are explained by social agency theory, in which social cues in a multimedia message prime a feeling of social partnership in the learner, which leads to deeper cognitive processing during learning, and results in a more meaningful learning outcome as reflected in transfer test performance.

Schools as Agents of Social Exclusion and Inclusion

ERIC Educational Resources Information Center

Razer, Michal; Friedman, Victor J.; Warshofsky, Boaz

2013-01-01

Although schools are usually regarded as important agents for social inclusion, research has shown that they may also function as agents of exclusion itself. The goal of this paper is to deepen our understanding of how schools function as agents of exclusion and how they can become more effective agents of inclusion. It is based on action research…

Agent Persuasion Mechanism of Acquaintance

NASA Astrophysics Data System (ADS)

Jinghua, Wu; Wenguang, Lu; Hailiang, Meng

Agent persuasion can improve negotiation efficiency in dynamic environment based on its initiative and autonomy, and etc., which is being affected much more by acquaintance. Classification of acquaintance on agent persuasion is illustrated, and the agent persuasion model of acquaintance is also illustrated. Then the concept of agent persuasion degree of acquaintance is given. Finally, relative interactive mechanism is elaborated.

13 CFR 120.950 - SBA and CDC must appoint agents.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 13 Business Credit and Assistance 1 2011-01-01 2011-01-01 false SBA and CDC must appoint agents... Development Company Loan Program (504) Debenture Sales and Service Agents § 120.950 SBA and CDC must appoint agents. SBA and the CDC must appoint the following agents to facilitate the sale and service of the...

9 CFR 121.4 - Overlap select agents and toxins.

Code of Federal Regulations, 2012 CFR

2012-01-01

... select agent or toxin to APHIS or CDC. (i) The seizure of any of the following overlap select agents and.... This report must be followed by submission of APHIS/CDC Form 4 within 7 calendar days after seizure of the overlap select agent or toxin. (ii) For all other overlap select agents or toxins, APHIS/CDC Form...

13 CFR 120.950 - SBA and CDC must appoint agents.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 13 Business Credit and Assistance 1 2012-01-01 2012-01-01 false SBA and CDC must appoint agents... Development Company Loan Program (504) Debenture Sales and Service Agents § 120.950 SBA and CDC must appoint agents. SBA and the CDC must appoint the following agents to facilitate the sale and service of the...

13 CFR 120.950 - SBA and CDC must appoint agents.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false SBA and CDC must appoint agents... Development Company Loan Program (504) Debenture Sales and Service Agents § 120.950 SBA and CDC must appoint agents. SBA and the CDC must appoint the following agents to facilitate the sale and service of the...

13 CFR 120.950 - SBA and CDC must appoint agents.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 13 Business Credit and Assistance 1 2013-01-01 2013-01-01 false SBA and CDC must appoint agents... Development Company Loan Program (504) Debenture Sales and Service Agents § 120.950 SBA and CDC must appoint agents. SBA and the CDC must appoint the following agents to facilitate the sale and service of the...

13 CFR 120.950 - SBA and CDC must appoint agents.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 13 Business Credit and Assistance 1 2014-01-01 2014-01-01 false SBA and CDC must appoint agents... Development Company Loan Program (504) Debenture Sales and Service Agents § 120.950 SBA and CDC must appoint agents. SBA and the CDC must appoint the following agents to facilitate the sale and service of the...

PCBs Alter Dopamine Mediated Function in Aging Workers

DTIC Science & Technology

2010-01-01

sympathomimetic agents, beta-adrenergic blocking agents, angiotensin-converting enzyme inhibitors, COX-2 inhibitors, other non - steroidal anti - inflammatory ...other non - steroidal anti - inflammatory agents, opiate agonists, miscellaneous analgesics and antipyretics, thyroid agents and antithyroid agents. ⁎ p...fold from peak values during occupational PCB use but remain elevated (two-fold) compared to a similar-aged non -occupationally exposed population

Automated monitoring of medical protocols: a secure and distributed architecture.

PubMed

Alsinet, T; Ansótegui, C; Béjar, R; Fernández, C; Manyà, F

2003-03-01

The control of the right application of medical protocols is a key issue in hospital environments. For the automated monitoring of medical protocols, we need a domain-independent language for their representation and a fully, or semi, autonomous system that understands the protocols and supervises their application. In this paper we describe a specification language and a multi-agent system architecture for monitoring medical protocols. We model medical services in hospital environments as specialized domain agents and interpret a medical protocol as a negotiation process between agents. A medical service can be involved in multiple medical protocols, and so specialized domain agents are independent of negotiation processes and autonomous system agents perform monitoring tasks. We present the detailed architecture of the system agents and of an important domain agent, the database broker agent, that is responsible of obtaining relevant information about the clinical history of patients. We also describe how we tackle the problems of privacy, integrity and authentication during the process of exchanging information between agents.

Autonomous Decentralized Voltage Profile Control of Super Distributed Energy System using Multi-agent Technology

NASA Astrophysics Data System (ADS)

Tsuji, Takao; Hara, Ryoichi; Oyama, Tsutomu; Yasuda, Keiichiro

A super distributed energy system is a future energy system in which the large part of its demand is fed by a huge number of distributed generators. At one time some nodes in the super distributed energy system behave as load, however, at other times they behave as generator - the characteristic of each node depends on the customers' decision. In such situation, it is very difficult to regulate voltage profile over the system due to the complexity of power flows. This paper proposes a novel control method of distributed generators that can achieve the autonomous decentralized voltage profile regulation by using multi-agent technology. The proposed multi-agent system employs two types of agent; a control agent and a mobile agent. Control agents generate or consume reactive power to regulate the voltage profile of neighboring nodes and mobile agents transmit the information necessary for VQ-control among the control agents. The proposed control method is tested through numerical simulations.

Emergence of trend trading and its effects in minority game

NASA Astrophysics Data System (ADS)

Liu, Xing-Hua; Liang, Xiao-Bei; Wang, Nai-Jing

2006-09-01

In this paper, we extended Minority Game (MG) by equipping agents with both value and trend strategies. In the new model, agents (we call them strong-adaptation agents) can autonomically select to act as trend trader or value trader when they game and learn in system. So the new model not only can reproduce stylized factors but also has the potential to investigate into the process of some problems of securities market. We investigated the dynamics of trend trading and its impacts on securities market based on the new model. Our research found that trend trading is inevitable when strong-adaptation agents make decisions by inductive reasoning. Trend trading (of strong-adaptation agents) is not irrational behavior but shows agent's strong-adaptation intelligence, because strong-adaptation agents can take advantage of the pure value agents when they game together in hybrid system. We also found that strong-adaptation agents do better in real environment. The results of our research are different with those of behavior finance researches.

Interaction and Communication of Agents in Networks and Language Complexity Estimates

NASA Technical Reports Server (NTRS)

Smid, Jan; Obitko, Marek; Fisher, David; Truszkowski, Walt

2004-01-01

Knowledge acquisition and sharing are arguably the most critical activities of communicating agents. We report about our on-going project featuring knowledge acquisition and sharing among communicating agents embedded in a network. The applications we target range from hardware robots to virtual entities such as internet agents. Agent experiments can be simulated using a convenient simulation language. We analyzed the complexity of communicating agent simulations using Java and Easel. Scenarios we have studied are listed below. The communication among agents can range from declarative queries to sub-natural language queries. 1) A set of agents monitoring an object are asked to build activity profiles based on exchanging elementary observations; 2) A set of car drivers form a line, where every car is following its predecessor. An unsafe distance cm create a strong wave in the line. Individual agents are asked to incorporate and apply directions how to avoid the wave. 3) A set of micro-vehicles form a grid and are asked to propagate information and concepts to a central server.

Can human-like Bots control collective mood: agent-based simulations of online chats

NASA Astrophysics Data System (ADS)

Tadić, Bosiljka; Šuvakov, Milovan

2013-10-01

Using an agent-based modeling approach, in this paper, we study self-organized dynamics of interacting agents in the presence of chat Bots. Different Bots with tunable ‘human-like’ attributes, which exchange emotional messages with agents, are considered, and the collective emotional behavior of agents is quantitatively analyzed. In particular, using detrended fractal analysis we determine persistent fluctuations and temporal correlations in time series of agent activity and statistics of avalanches carrying emotional messages of agents when Bots favoring positive/negative affects are active. We determine the impact of Bots and identify parameters that can modulate that impact. Our analysis suggests that, by these measures, the emotional Bots induce collective emotion among interacting agents by suitably altering the fractal characteristics of the underlying stochastic process. Positive emotion Bots are slightly more effective than negative emotion Bots. Moreover, Bots which periodically alternate between positive and negative emotion can enhance fluctuations in the system, leading to avalanches of agent messages that are reminiscent of self-organized critical states.

Effects of Manipulation on Attributions of Causation, Free Will, and Moral Responsibility.

PubMed

Murray, Dylan; Lombrozo, Tania

2017-03-01

If someone brings about an outcome without intending to, is she causally and morally responsible for it? What if she acts intentionally, but as the result of manipulation by another agent? Previous research has shown that an agent's mental states can affect attributions of causal and moral responsibility to that agent, but little is known about what effect one agent's mental states can have on attributions to another agent. In Experiment 1, we replicate findings that manipulation lowers attributions of responsibility to manipulated agents. Experiments 2-7 isolate which features of manipulation drive this effect, a crucial issue for both philosophical debates about free will and attributions of responsibility in situations involving social influence more generally. Our results suggest that "bypassing" a manipulated agent's mental states generates the greatest reduction in responsibility, and we explain our results in terms of the effects that one agent's mental states can have on the counterfactual relations between another agent and an outcome. Copyright © 2016 Cognitive Science Society, Inc.

A development framework for distributed artificial intelligence

NASA Technical Reports Server (NTRS)

Adler, Richard M.; Cottman, Bruce H.

1989-01-01

The authors describe distributed artificial intelligence (DAI) applications in which multiple organizations of agents solve multiple domain problems. They then describe work in progress on a DAI system development environment, called SOCIAL, which consists of three primary language-based components. The Knowledge Object Language defines models of knowledge representation and reasoning. The metaCourier language supplies the underlying functionality for interprocess communication and control access across heterogeneous computing environments. The metaAgents language defines models for agent organization coordination, control, and resource management. Application agents and agent organizations will be constructed by combining metaAgents and metaCourier building blocks with task-specific functionality such as diagnostic or planning reasoning. This architecture hides implementation details of communications, control, and integration in distributed processing environments, enabling application developers to concentrate on the design and functionality of the intelligent agents and agent networks themselves.

Agent oriented programming: An overview of the framework and summary of recent research

NASA Technical Reports Server (NTRS)

Shoham, Yoav

1993-01-01

This is a short overview of the agent-oriented programming (AOP) framework. AOP can be viewed as an specialization of object-oriented programming. The state of an agent consists of components called beliefs, choices, capabilities, commitments, and possibly others; for this reason the state of an agent is called its mental state. The mental state of agents is captured formally in an extension of standard epistemic logics: beside temporalizing the knowledge and belief operators, AOP introduces operators for commitment, choice and capability. Agents are controlled by agent programs, which include primitives for communicating with other agents. In the spirit of speech-act theory, each communication primitive is of a certain type: informing, requesting, offering, etc. This document describes these features in more detail and summarizes recent results and ongoing AOP-related work.

Hydrolysis of Synthetic Esters by the Antibacterial Agent in Serum

PubMed Central

Yotis, William W.

1966-01-01

Yotis, William W. (Loyola University, Chicago, Ill.). Hydrolysis of synthetic esters by the antibacterial agent in serum. J. Bacteriol. 91:488–493. 1966.—An antistaphylococcal serum agent was assayed colorimetrically, manometrically, and titrimetrically for esterase activity. p-Nitrophenol acetate, triacetin, l-lysine methyl and ethyl ester, and norleucine methyl ester were hydrolyzed by the antistaphylococcal agent. Acetylcholine and benzoylcholine esters, triolein, tristearin, and p-tosylarginine methyl ester were not attacked by this agent. With p-nitrophenol acetate as substrate, optimal activity occurred at pH 7.4. Incubation at 60 C for 30 min reduced drastically the esterase activity of the antistaphylococcal agent, and incubation at 75 C for 30 min abolished the esterase activity of this agent. Almost complete inhibition of esterase activity was observed with 0.001 m HgCl2, ZnSO4, and ethylenediaminetetraacetic acid (EDTA). EDTA inhibition could be reversed by the addition of CaCl2, but not MgCl2. Cysteine reversed the inhibition of HgCl2. NaF, atoxyl, diisopropyl fluorophosphate, quinine, and physostigmine did not influence the esterase activity of the antibacterial agent. The demonstration of esterase activity of both the antistaphylococcal agent and coagulase may shed further light on the reported ability of coagulase to neutralize the antistaphylococcal activity of this agent, or the prevention of absorption of the agent on the staphylococcal cell surface. In addition, the colorimetric procedure described in this report may be a convenient tool in assaying the potency of the antistaphylococcal agent. Images PMID:4956776

Consentaneous Agent-Based and Stochastic Model of the Financial Markets

PubMed Central

Gontis, Vygintas; Kononovicius, Aleksejus

2014-01-01

We are looking for the agent-based treatment of the financial markets considering necessity to build bridges between microscopic, agent based, and macroscopic, phenomenological modeling. The acknowledgment that agent-based modeling framework, which may provide qualitative and quantitative understanding of the financial markets, is very ambiguous emphasizes the exceptional value of well defined analytically tractable agent systems. Herding as one of the behavior peculiarities considered in the behavioral finance is the main property of the agent interactions we deal with in this contribution. Looking for the consentaneous agent-based and macroscopic approach we combine two origins of the noise: exogenous one, related to the information flow, and endogenous one, arising form the complex stochastic dynamics of agents. As a result we propose a three state agent-based herding model of the financial markets. From this agent-based model we derive a set of stochastic differential equations, which describes underlying macroscopic dynamics of agent population and log price in the financial markets. The obtained solution is then subjected to the exogenous noise, which shapes instantaneous return fluctuations. We test both Gaussian and q-Gaussian noise as a source of the short term fluctuations. The resulting model of the return in the financial markets with the same set of parameters reproduces empirical probability and spectral densities of absolute return observed in New York, Warsaw and NASDAQ OMX Vilnius Stock Exchanges. Our result confirms the prevalent idea in behavioral finance that herding interactions may be dominant over agent rationality and contribute towards bubble formation. PMID:25029364

Technological advancements for the detection of and protection against biological and chemical warfare agents.

PubMed

Eubanks, Lisa M; Dickerson, Tobin J; Janda, Kim D

2007-03-01

There is a growing need for technological advancements to combat agents of chemical and biological warfare, particularly in the context of the deliberate use of a chemical and/or biological warfare agent by a terrorist organization. In this tutorial review, we describe methods that have been developed both for the specific detection of biological and chemical warfare agents in a field setting, as well as potential therapeutic approaches for treating exposure to these toxic species. In particular, nerve agents are described as a typical chemical warfare agent, and the two potent biothreat agents, anthrax and botulinum neurotoxin, are used as illustrative examples of potent weapons for which countermeasures are urgently needed.

Promoting motivation with virtual agents and avatars: role of visual presence and appearance.

PubMed

Baylor, Amy L

2009-12-12

Anthropomorphic virtual agents can serve as powerful technological mediators to impact motivational outcomes such as self-efficacy and attitude change. Such anthropomorphic agents can be designed as simulated social models in the Bandurian sense, providing social influence as virtual 'role models'. Of particular value is the capacity for designing such agents as optimized social models for a target audience and context. Importantly, the visual presence and appearance of such agents can have a major impact on motivation and affect regardless of the underlying technical sophistication. Empirical results of different instantiations of agent presence and appearance are reviewed for both autonomous virtual agents and avatars that represent a user.

Collaborating Fuzzy Reinforcement Learning Agents

NASA Technical Reports Server (NTRS)

Berenji, Hamid R.

1997-01-01

Earlier, we introduced GARIC-Q, a new method for doing incremental Dynamic Programming using a society of intelligent agents which are controlled at the top level by Fuzzy Relearning and at the local level, each agent learns and operates based on ANTARCTIC, a technique for fuzzy reinforcement learning. In this paper, we show that it is possible for these agents to compete in order to affect the selected control policy but at the same time, they can collaborate while investigating the state space. In this model, the evaluator or the critic learns by observing all the agents behaviors but the control policy changes only based on the behavior of the winning agent also known as the super agent.

Multi-Agent Design and Implementation for an Online Peer Help System

ERIC Educational Resources Information Center

Meng, Anbo

2014-01-01

With the rapid advance of e-learning, the online peer help is playing increasingly important role. This paper explores the application of MAS to an online peer help system (MAPS). In the design phase, the architecture of MAPS is proposed, which consists of a set of agents including the personal agent, the course agent, the diagnosis agent, the DF…

A STUDY OF NORTH CAROLINA AGRICULTURAL EXTENSION AGENTS' PERCEPTION OF THE ROLE OF FERTILIZER DEALERS IN EXTENSION PROGRAMMING.

ERIC Educational Resources Information Center

WOODARD, BRUCE H.

A QUESTIONNAIRE MAILED TO 98 AGRICULTURAL EXTENSION AGENTS IN NORTH CAROLINA WITH PRIMARY RESPONSIBILITY IN AGRONOMY IN THEIR COUNTIES WAS USED TO COLLECT DATA ON THE AGENTS' PERCEPTION OF THE NATURE AND FREQUENCY OF PERFORMANCE BY DEALERS IN SOIL FERTILITY PROGRAMS, AGENTS' FEELINGS ABOUT DEALER PARTICIPATION, AND THE ASSOCIATION BETWEEN AGENTS'…

KODAMA and VPC based Framework for Ubiquitous Systems and its Experiment

NASA Astrophysics Data System (ADS)

Takahashi, Kenichi; Amamiya, Satoshi; Iwao, Tadashige; Zhong, Guoqiang; Kainuma, Tatsuya; Amamiya, Makoto

Recently, agent technologies have attracted a lot of interest as an emerging programming paradigm. With such agent technologies, services are provided through collaboration among agents. At the same time, the spread of mobile technologies and communication infrastructures has made it possible to access the network anytime and from anywhere. Using agents and mobile technologies to realize ubiquitous computing systems, we propose a new framework based on KODAMA and VPC. KODAMA provides distributed management mechanisms by using the concept of community and communication infrastructure to deliver messages among agents without agents being aware of the physical network. VPC provides a method of defining peer-to-peer services based on agent communication with policy packages. By merging the characteristics of both KODAMA and VPC functions, we propose a new framework for ubiquitous computing environments. It provides distributed management functions according to the concept of agent communities, agent communications which are abstracted from the physical environment, and agent collaboration with policy packages. Using our new framework, we conducted a large-scale experiment in shopping malls in Nagoya, which sent advertisement e-mails to users' cellular phones according to user location and attributes. The empirical results showed that our new framework worked effectively for sales in shopping malls.

A distributed agent architecture for real-time knowledge-based systems: Real-time expert systems project, phase 1

NASA Technical Reports Server (NTRS)

Lee, S. Daniel

1990-01-01

We propose a distributed agent architecture (DAA) that can support a variety of paradigms based on both traditional real-time computing and artificial intelligence. DAA consists of distributed agents that are classified into two categories: reactive and cognitive. Reactive agents can be implemented directly in Ada to meet hard real-time requirements and be deployed on on-board embedded processors. A traditional real-time computing methodology under consideration is the rate monotonic theory that can guarantee schedulability based on analytical methods. AI techniques under consideration for reactive agents are approximate or anytime reasoning that can be implemented using Bayesian belief networks as in Guardian. Cognitive agents are traditional expert systems that can be implemented in ART-Ada to meet soft real-time requirements. During the initial design of cognitive agents, it is critical to consider the migration path that would allow initial deployment on ground-based workstations with eventual deployment on on-board processors. ART-Ada technology enables this migration while Lisp-based technologies make it difficult if not impossible. In addition to reactive and cognitive agents, a meta-level agent would be needed to coordinate multiple agents and to provide meta-level control.

Efficient Agent-Based Cluster Ensembles

NASA Technical Reports Server (NTRS)

Agogino, Adrian; Tumer, Kagan

2006-01-01

Numerous domains ranging from distributed data acquisition to knowledge reuse need to solve the cluster ensemble problem of combining multiple clusterings into a single unified clustering. Unfortunately current non-agent-based cluster combining methods do not work in a distributed environment, are not robust to corrupted clusterings and require centralized access to all original clusterings. Overcoming these issues will allow cluster ensembles to be used in fundamentally distributed and failure-prone domains such as data acquisition from satellite constellations, in addition to domains demanding confidentiality such as combining clusterings of user profiles. This paper proposes an efficient, distributed, agent-based clustering ensemble method that addresses these issues. In this approach each agent is assigned a small subset of the data and votes on which final cluster its data points should belong to. The final clustering is then evaluated by a global utility, computed in a distributed way. This clustering is also evaluated using an agent-specific utility that is shown to be easier for the agents to maximize. Results show that agents using the agent-specific utility can achieve better performance than traditional non-agent based methods and are effective even when up to 50% of the agents fail.

The influence of retraction agents on cytoskeleton reorganization and oxidative stress in primary human gingival fibroblasts (HGFs).

PubMed

Nowakowska, Danuta; Saczko, Jolanta; Bieżuńska-Kusiak, Katarzyna; Choromańska, Anna; Dubińska-Magiera, Magda; Ziętek, Marek; Kulbacka, Julita

2014-03-01

Contemporary gingival retraction chemicals are not without disagreeable side-effects; there appears to be no best gingival retraction agent. The aim of this research was to select the most biocompatible retraction agents based on examination of the parameters of oxidative stress in fibroblasts derived from human primary cell culture. In this in vitro study we evaluated parameters of oxidative stress after treatment with retraction agents. Visine, Afrin, Neosynephrin, Strazolin and Adrenaline were the commercial products studied as gingival retraction agents. Additionally we examined three experimental agents. We determined lipid peroxidation and protein damage and monitored changes in cellular cytoskeleton proteins. Proliferative and survival efficiency were also evaluated. Oxidative changes included by evaluated retraction agents were at the lowest level in the case of the experimental gels. Also cytoskeleton observations suggest that the experimental agents did not degrade the cellular structure of human gingival fibroblasts (HGFs). The current study was performed because of a need to project new nontoxic and save retraction agents for peridontological therapeutic usage. We suggest that the new investigational gels are most biocompatible with periodontal tissues and can be applied as new vasoconstrictor chemical retraction agents. Copyright © 2014 Elsevier Ltd. All rights reserved.

[Exposure to biological agents used in Polish enterprises: analysis of data derived from the National Register of Biological Agent].

PubMed

Kozajda, Anna; Szadkowska-Stańczyk, Irena

2011-01-01

The National Register of Biological Agents at Work and the National Information Centre for Biological Agents Present at Workplaces were established in the Nofer Institute of Occupational Medicine in 2005. The National Information Centre carries out consultation and education activities concerning occupational exposure and risk assessment, development and implementation of preventive programs and accurate registration of reliable information about the use of biological agents. Educational materials on biological exposure are published on the website. The National Register of Biological Agents (database) collects and periodically analyzes the information obtained from employers about the use of biological agents for research, diagnostic or industrial purposes. As of 10 December 2010 there were 240 notifications from companies, which use biological agents for the following purposes: research--69, industrial--30 and diagnostic--321. Near 75% of all notifications were obtained from different diagnostic laboratories (public and private). In total, 3226 workers, including 2967 (92%) women and 256 (8%) men were exposed to biological agents. In general, occupational exposure to 209 biological agents (186 of risk group 2 and 23 of risk group 3, of which 16 are additionally marked by 3**) were registered in the data base.

Adaptive behaviors in multi-agent source localization using passive sensing.

PubMed

Shaukat, Mansoor; Chitre, Mandar

2016-12-01

In this paper, the role of adaptive group cohesion in a cooperative multi-agent source localization problem is investigated. A distributed source localization algorithm is presented for a homogeneous team of simple agents. An agent uses a single sensor to sense the gradient and two sensors to sense its neighbors. The algorithm is a set of individualistic and social behaviors where the individualistic behavior is as simple as an agent keeping its previous heading and is not self-sufficient in localizing the source. Source localization is achieved as an emergent property through agent's adaptive interactions with the neighbors and the environment. Given a single agent is incapable of localizing the source, maintaining team connectivity at all times is crucial. Two simple temporal sampling behaviors, intensity-based-adaptation and connectivity-based-adaptation, ensure an efficient localization strategy with minimal agent breakaways. The agent behaviors are simultaneously optimized using a two phase evolutionary optimization process. The optimized behaviors are estimated with analytical models and the resulting collective behavior is validated against the agent's sensor and actuator noise, strong multi-path interference due to environment variability, initialization distance sensitivity and loss of source signal.

A Scalable and Robust Multi-Agent Approach to Distributed Optimization

NASA Technical Reports Server (NTRS)

Tumer, Kagan

2005-01-01

Modularizing a large optimization problem so that the solutions to the subproblems provide a good overall solution is a challenging problem. In this paper we present a multi-agent approach to this problem based on aligning the agent objectives with the system objectives, obviating the need to impose external mechanisms to achieve collaboration among the agents. This approach naturally addresses scaling and robustness issues by ensuring that the agents do not rely on the reliable operation of other agents We test this approach in the difficult distributed optimization problem of imperfect device subset selection [Challet and Johnson, 2002]. In this problem, there are n devices, each of which has a "distortion", and the task is to find the subset of those n devices that minimizes the average distortion. Our results show that in large systems (1000 agents) the proposed approach provides improvements of over an order of magnitude over both traditional optimization methods and traditional multi-agent methods. Furthermore, the results show that even in extreme cases of agent failures (i.e., half the agents fail midway through the simulation) the system remains coordinated and still outperforms a failure-free and centralized optimization algorithm.

Cranial nerve contrast using nerve-specific fluorophores improved by paired-agent imaging with indocyanine green as a control agent

NASA Astrophysics Data System (ADS)

Torres, Veronica C.; Vuong, Victoria D.; Wilson, Todd; Wewel, Joshua; Byrne, Richard W.; Tichauer, Kenneth M.

2017-09-01

Nerve preservation during surgery is critical because damage can result in significant morbidity. This remains a challenge especially for skull base surgeries where cranial nerves (CNs) are involved because visualization and access are particularly poor in that location. We present a paired-agent imaging method to enhance identification of CNs using nerve-specific fluorophores. Two myelin-targeting imaging agents were evaluated, Oxazine 4 and Rhodamine 800, and coadministered with a control agent, indocyanine green, either intravenously or topically in rats. Fluorescence imaging was performed on excised brains ex vivo, and nerve contrast was evaluated via paired-agent ratiometric data analysis. Although contrast was improved among all experimental groups using paired-agent imaging compared to conventional, solely targeted imaging, Oxazine 4 applied directly exhibited the greatest enhancement, with a minimum 3 times improvement in CNs delineation. This work highlights the importance of accounting for nonspecific signal of targeted agents, and demonstrates that paired-agent imaging is one method capable of doing so. Although staining, rinsing, and imaging protocols need to be optimized, these findings serve as a demonstration for the potential use of paired-agent imaging to improve contrast of CNs, and consequently, surgical outcome.

Chemical terrorism for the intensivist.

PubMed

Chalela, Julio A; Burnett, Thomas

2012-05-01

The use of chemical agents for terrorist attacks or military warfare is a major concern at the present time. Chemical agents can cause significant morbidity, are relatively inexpensive, and are easy to store and use. Weaponization of chemical agents is only limited by the physicochemical properties of some agents. Recent incidents involving toxic industrial chemicals and chemical terrorist attacks indicate that critical care services are frequently utilized. For obvious reasons, the critical care literature on chemical terrorism is scarce. This article reviews the clinical aspects of diagnosing and treating victims of chemical terrorism while emphasizing the critical care management. The intensivist needs to be familiar with the chemical agents that could be used in a terrorist attack. The military classification divides agents into lung agents, blood agents, vesicants, and nerve agents. Supportive critical care is the cornerstone of treatment for most casualties, and dramatic recovery can occur in many cases. Specific antidotes are available for some agents, but even without the antidote, aggressive intensive care support can lead to favorable outcome in many cases. Critical care and emergency services can be overwhelmed by a terrorist attack as many exposed but not ill will seek care.

Embodied artificial agents for understanding human social cognition.

PubMed

Wykowska, Agnieszka; Chaminade, Thierry; Cheng, Gordon

2016-05-05

In this paper, we propose that experimental protocols involving artificial agents, in particular the embodied humanoid robots, provide insightful information regarding social cognitive mechanisms in the human brain. Using artificial agents allows for manipulation and control of various parameters of behaviour, appearance and expressiveness in one of the interaction partners (the artificial agent), and for examining effect of these parameters on the other interaction partner (the human). At the same time, using artificial agents means introducing the presence of artificial, yet human-like, systems into the human social sphere. This allows for testing in a controlled, but ecologically valid, manner human fundamental mechanisms of social cognition both at the behavioural and at the neural level. This paper will review existing literature that reports studies in which artificial embodied agents have been used to study social cognition and will address the question of whether various mechanisms of social cognition (ranging from lower- to higher-order cognitive processes) are evoked by artificial agents to the same extent as by natural agents, humans in particular. Increasing the understanding of how behavioural and neural mechanisms of social cognition respond to artificial anthropomorphic agents provides empirical answers to the conundrum 'What is a social agent?' © 2016 The Authors.

Muriel Driver Memorial Lecture 2013: Embracing our role as change agents.

PubMed

Finlayson, Marcia L

2013-10-01

Given the nature of occupational therapy philosophy and practice, it is not surprising that "change agent" has been identified as one of the seven professional roles that occupational therapists fulfill. This Muriel Driver lecture examines the change agent role, what it means, and what knowledge, skills, and personal qualities are necessary to be effective. Overall, relatively little has been written about the change agent role in the occupational therapy literature. Much of what does exist is implicit and often embedded in related topics, such as advocacy. An examination of literature from outside of occupational therapy uncovered four major themes about this role: (a) Change agents are insightful, reflective, and disciplined; (b) Charnge agents are visionary leaders and mobilizers; (c) Change agents are knowledge integrators and translators; and (d) Change agents are diplomatic interventionists who produce meaningful outcomes. These themes point to several areas of silence in the occupational therapy literature. Overcoming these areas of silence and moving forward will require open, challenging, and scholarly debates; reconsideration of change agent role competencies; and clear messaging that we all have the capacity to be competent and effective change agents regardless of our title or setting.

Agent autonomy approach to probabilistic physics-of-failure modeling of complex dynamic systems with interacting failure mechanisms

NASA Astrophysics Data System (ADS)

Gromek, Katherine Emily

A novel computational and inference framework of the physics-of-failure (PoF) reliability modeling for complex dynamic systems has been established in this research. The PoF-based reliability models are used to perform a real time simulation of system failure processes, so that the system level reliability modeling would constitute inferences from checking the status of component level reliability at any given time. The "agent autonomy" concept is applied as a solution method for the system-level probabilistic PoF-based (i.e. PPoF-based) modeling. This concept originated from artificial intelligence (AI) as a leading intelligent computational inference in modeling of multi agents systems (MAS). The concept of agent autonomy in the context of reliability modeling was first proposed by M. Azarkhail [1], where a fundamentally new idea of system representation by autonomous intelligent agents for the purpose of reliability modeling was introduced. Contribution of the current work lies in the further development of the agent anatomy concept, particularly the refined agent classification within the scope of the PoF-based system reliability modeling, new approaches to the learning and the autonomy properties of the intelligent agents, and modeling interacting failure mechanisms within the dynamic engineering system. The autonomous property of intelligent agents is defined as agent's ability to self-activate, deactivate or completely redefine their role in the analysis. This property of agents and the ability to model interacting failure mechanisms of the system elements makes the agent autonomy fundamentally different from all existing methods of probabilistic PoF-based reliability modeling. 1. Azarkhail, M., "Agent Autonomy Approach to Physics-Based Reliability Modeling of Structures and Mechanical Systems", PhD thesis, University of Maryland, College Park, 2007.

Joint chemical agent detector (JCAD): the future of chemical agent detection

NASA Astrophysics Data System (ADS)

Laljer, Charles E.

2003-08-01

The Joint Chemical Agent Detector (JCAD) has continued development through 2002. The JCAD has completed Contractor Validation Testing (CVT) that included chemical warfare agent testing, environmental testing, electromagnetic interferent testing, and platform integration validation. The JCAD provides state of the art chemical warfare agent detection capability to military and homeland security operators. Intelligence sources estimate that over twenty countries have active chemical weapons programs. The spread of weapons of mass destruction (and the industrial capability for manufacture of these weapons) to third world nations and terrorist organizations has greatly increased the chemical agent threat to U.S. interests. Coupled with the potential for U.S. involvement in localized conflicts in an operational or support capacity, increases the probability that the military Joint Services may encounter chemical agents anywhere in the world. The JCAD is a small (45 in3), lightweight (2 lb.) chemical agent detector for vehicle interiors, aircraft, individual personnel, shipboard, and fixed site locations. The system provides a common detection component across multi-service platforms. This common detector system will allow the Joint Services to use the same operational and support concept for more efficient utilization of resources. The JCAD detects, identifies, quantifies, and warns of the presence of chemical agents prior to onset of miosis. Upon detection of chemical agents, the detector provides local and remote audible and visual alarms to the operators. Advance warning will provide the vehicle crew and other personnel in the local area with the time necessary to protect themselves from the lethal effects of chemical agents. The JCAD is capable of being upgraded to protect against future chemical agent threats. The JCAD provides the operator with the warning necessary to survive and fight in a chemical warfare agent threat environment.

Cognitive, cultural, and linguistic sources of a handshape distinction expressing agentivity.

PubMed

Brentari, Diane; Di Renzo, Alessio; Keane, Jonathan; Volterra, Virginia

2015-01-01

In this paper the cognitive, cultural, and linguistic bases for a pattern of conventionalization of two types of iconic handshapes are described. Work on sign languages has shown that handling handshapes (H-HSs: those that represent how objects are handled or manipulated) and object handshapes (O-HSs: those that represent the class, size, or shape of objects) express an agentive/non-agentive semantic distinction in many sign languages. H-HSs are used in agentive event descriptions and O-HSs are used in non-agentive event descriptions. In this work, American Sign Language (ASL) and Italian Sign Language (LIS) productions are compared (adults and children) as well as the corresponding groups of gesturers in each country using "silent gesture." While the gesture groups, in general, did not employ an H-HS/O-HS distinction, all participants (signers and gesturers) used iconic handshapes (H-HSs and O-HSs together) more often in agentive than in no-agent event descriptions; moreover, none of the subjects produced an opposite pattern than the expected one (i.e., H-HSs associated with no-agent descriptions and O-HSs associated with agentive ones). These effects are argued to be grounded in cognition. In addition, some individual gesturers were observed to produce the H-HS/O-HS opposition for agentive and non-agentive event descriptions-that is, more Italian than American adult gesturers. This effect is argued to be grounded in culture. Finally, the agentive/non-agentive handshape opposition is confirmed for signers of ASL and LIS, but previously unreported cross-linguistic differences were also found across both adult and child sign groups. It is, therefore, concluded that cognitive, cultural, and linguistic factors contribute to the conventionalization of this distinction of handshape type. Copyright © 2014 Cognitive Science Society, Inc.

Do Low Molecular Weight Agents Cause More Severe Asthma than High Molecular Weight Agents?

PubMed

Meca, Olga; Cruz, María-Jesús; Sánchez-Ortiz, Mónica; González-Barcala, Francisco-Javier; Ojanguren, Iñigo; Munoz, Xavier

2016-01-01

The aim of this study was to analyse whether patients with occupational asthma (OA) caused by low molecular weight (LMW) agents differed from patients with OA caused by high molecular weight (HMW) with regard to risk factors, asthma presentation and severity, and response to various diagnostic tests. Seventy-eight patients with OA diagnosed by positive specific inhalation challenge (SIC) were included. Anthropometric characteristics, atopic status, occupation, latency periods, asthma severity according to the Global Initiative for Asthma (GINA) control classification, lung function tests and SIC results were analysed. OA was induced by an HMW agent in 23 patients (29%) and by an LMW agent in 55 (71%). A logistic regression analysis confirmed that patients with OA caused by LMW agents had a significantly higher risk of severity according to the GINA classification after adjusting for potential confounders (OR = 3.579, 95% CI 1.136-11.280; p = 0.029). During the SIC, most patients with OA caused by HMW agents presented an early reaction (82%), while in patients with OA caused by LMW agents the response was mainly late (73%) (p = 0.0001). Similarly, patients with OA caused by LMW agents experienced a greater degree of bronchial hyperresponsiveness, measured as the difference in the methacholine dose-response ratio (DRR) before and after SIC (1.77, range 0-16), compared with patients with OA caused by HMW agents (0.87, range 0-72), (p = 0.024). OA caused by LMW agents may be more severe than that caused by HMW agents. The severity of the condition may be determined by the different mechanisms of action of these agents.

Design Principles of Nanoparticles as Contrast Agents for Magnetic Resonance Imaging

NASA Astrophysics Data System (ADS)

Shan, Liang; Gu, Xinbin; Wang, Paul

2013-09-01

Molecular imaging is an emerging field that introduces molecular agents into traditional imaging techniques, enabling visualization, characterization and measurement of biological processes at the molecular and cellular levels in humans and other living systems. The promise of molecular imaging lies in its potential for selective potency by targeting biomarkers or molecular targets and the imaging agents serve as reporters for the selectivity of targeting. Development of an efficient molecular imaging agent depends on well-controlled high-quality experiment design involving target selection, agent synthesis, in vitro characterization, and in vivo animal characterization before it is applied in humans. According to the analysis from the Molecular Imaging and Contrast Agent Database (MICAD, ), more than 6000 molecular imaging agents with sufficient preclinical evaluation have been reported to date in the literature and this number increases by 250-300 novel agents each year. The majority of these agents are radionuclides, which are developed for positron emission tomography (PET) and single photon emission computed tomography (SPECT). Contrast agents for magnetic resonance imaging (MRI) account for only a small part. This is largely due to the fact that MRI is currently not a fully quantitative imaging technique and is less sensitive than PET and SPECT. However, because of the superior ability to simultaneously extract molecular and anatomic information, molecular MRI is attracting significant interest and various targeted nanoparticle contrast agents have been synthesized for MRI. The first and one of the most critical steps in developing a targeted nanoparticle contrast agent is target selection, which plays the central role and forms the basis for success of molecular imaging. This chapter discusses the design principles of targeted contrast agents in the emerging frontiers of molecular MRI.

30 CFR 250.145 - How do I designate an agent or a local agent?

Code of Federal Regulations, 2010 CFR

2010-07-01

... agent empowered to fulfill your obligations under the Act, the lease, or the regulations in this part... agent empowered to receive notices and submit requests, applications, notices, or supplemental...

How gestures affect students: A comparative experiment using class presentations conducted by an anthropomorphic agent

NASA Astrophysics Data System (ADS)

Shirakawa, Tomohiro; Sato, Hiroshi; Imao, Tomoya

2017-07-01

Recently, a variety of user interfaces have been developed based on human-robot and human-agent interaction, and anthropomorphic agents are used as one type of interface. However, the use of anthropomorphic agents is applied mainly to the medical and cognitive sciences, and there are few studies of their application to other fields. Therefore, we used an anthropomorphic agent of MMD in a virtual lecture to analyze the effect of gestures on students and search for ways to apply anthropomorphic agents to the field of educational technology.

Exhaustive search system and method using space-filling curves

DOEpatents

Spires, Shannon V.

2003-10-21

A search system and method for one agent or for multiple agents using a space-filling curve provides a way to control one or more agents to cover an area of any space of any dimensionality using an exhaustive search pattern. An example of the space-filling curve is a Hilbert curve. The search area can be a physical geography, a cyberspace search area, or an area searchable by computing resources. The search agent can be one or more physical agents, such as a robot, and can be software agents for searching cyberspace.

MIDAS: a practical Bayesian design for platform trials with molecularly targeted agents.

PubMed

Yuan, Ying; Guo, Beibei; Munsell, Mark; Lu, Karen; Jazaeri, Amir

2016-09-30

Recent success of immunotherapy and other targeted therapies in cancer treatment has led to an unprecedented surge in the number of novel therapeutic agents that need to be evaluated in clinical trials. Traditional phase II clinical trial designs were developed for evaluating one candidate treatment at a time and thus not efficient for this task. We propose a Bayesian phase II platform design, the multi-candidate iterative design with adaptive selection (MIDAS), which allows investigators to continuously screen a large number of candidate agents in an efficient and seamless fashion. MIDAS consists of one control arm, which contains a standard therapy as the control, and several experimental arms, which contain the experimental agents. Patients are adaptively randomized to the control and experimental agents based on their estimated efficacy. During the trial, we adaptively drop inefficacious or overly toxic agents and 'graduate' the promising agents from the trial to the next stage of development. Whenever an experimental agent graduates or is dropped, the corresponding arm opens immediately for testing the next available new agent. Simulation studies show that MIDAS substantially outperforms the conventional approach. The proposed design yields a significantly higher probability for identifying the promising agents and dropping the futile agents. In addition, MIDAS requires only one master protocol, which streamlines trial conduct and substantially decreases the overhead burden. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

MIDAS: A Practical Bayesian Design for Platform Trials with Molecularly Targeted Agents

PubMed Central

Yuan, Ying; Guo, Beibei; Munsell, Mark; Lu, Karen; Jazaeri, Amir

2016-01-01

Recent success of immunotherapy and other targeted therapies in cancer treatment has led to an unprecedented surge in the number of novel therapeutic agents that need to be evaluated in clinical trials. Traditional phase II clinical trial designs were developed for evaluating one candidate treatment at a time, and thus not efficient for this task. We propose a Bayesian phase II platform design, the Multi-candidate Iterative Design with Adaptive Selection (MIDAS), which allows investigators to continuously screen a large number of candidate agents in an efficient and seamless fashion. MIDAS consists of one control arm, which contains a standard therapy as the control, and several experimental arms, which contain the experimental agents. Patients are adaptively randomized to the control and experimental agents based on their estimated efficacy. During the trial, we adaptively drop inefficacious or overly toxic agents and “graduate” the promising agents from the trial to the next stage of development. Whenever an experimental agent graduates or is dropped, the corresponding arm opens immediately for testing the next available new agent. Simulation studies show that MIDAS substantially outperforms the conventional approach. The proposed design yields a significantly higher probability for identifying the promising agents and dropping the futile agents. In addition, MIDAS requires only one master protocol, which streamlines trial conduct and substantially decreases the overhead burden. PMID:27112322

Product Categories under the National Contingency Plan Subpart J

EPA Pesticide Factsheets

There are five types authorized for use in oil spill cleanups, defined in 40 CFR 300.5. They are bioremediation agents, dispersants, sorbents, surface collecting agents, surface washing agents, and miscellaneous oil spill control agents.

30 CFR 550.145 - How do I designate an agent or a local agent?

Code of Federal Regulations, 2012 CFR

2012-07-01

... designate an agent empowered to fulfill your obligations under the Act, the lease, or the regulations in... local agent empowered to receive notices and submit requests, applications, notices, or supplemental...

30 CFR 550.145 - How do I designate an agent or a local agent?

Code of Federal Regulations, 2013 CFR

2013-07-01

... designate an agent empowered to fulfill your obligations under the Act, the lease, or the regulations in... local agent empowered to receive notices and submit requests, applications, notices, or supplemental...

30 CFR 250.145 - How do I designate an agent or a local agent?

Code of Federal Regulations, 2011 CFR

2011-07-01

... Director may require you to designate an agent empowered to fulfill your obligations under the Act, the... Regional Supervisor's approval a local agent empowered to receive notices and submit requests, applications...

30 CFR 550.145 - How do I designate an agent or a local agent?

Code of Federal Regulations, 2014 CFR

2014-07-01

... designate an agent empowered to fulfill your obligations under the Act, the lease, or the regulations in... local agent empowered to receive notices and submit requests, applications, notices, or supplemental...

Antithrombogenic Polymer Coating.

DOEpatents

Huang, Zhi Heng; McDonald, William F.; Wright, Stacy C.; Taylor, Andrew C.

2003-01-21

An article having a non-thrombogenic surface and a process for making the article are disclosed. The article is formed by (i) coating a polymeric substrate with a crosslinked chemical combination of a polymer having at least two amino substituted side chains, a crosslinking agent containing at least two crosslinking functional groups which react with amino groups on the polymer, and a linking agent containing a first functional group which reacts with a third functional group of the crosslinking agent, and (ii) contacting the coating on the substrate with an antithrombogenic agent which covalently bonds to a second functional group of the linking agent. In one example embodiment, the polymer is a polyamide having amino substituted alkyl chains on one side of the polyamide backbone, the crosslinking agent is a phosphine having the general formula (A).sub.3 P wherein A is hydroxyalkyl, the linking agent is a polyhydrazide and the antithrombogenic agent is heparin.

Emotional Multiagent Reinforcement Learning in Spatial Social Dilemmas.

PubMed

Yu, Chao; Zhang, Minjie; Ren, Fenghui; Tan, Guozhen

2015-12-01

Social dilemmas have attracted extensive interest in the research of multiagent systems in order to study the emergence of cooperative behaviors among selfish agents. Understanding how agents can achieve cooperation in social dilemmas through learning from local experience is a critical problem that has motivated researchers for decades. This paper investigates the possibility of exploiting emotions in agent learning in order to facilitate the emergence of cooperation in social dilemmas. In particular, the spatial version of social dilemmas is considered to study the impact of local interactions on the emergence of cooperation in the whole system. A double-layered emotional multiagent reinforcement learning framework is proposed to endow agents with internal cognitive and emotional capabilities that can drive these agents to learn cooperative behaviors. Experimental results reveal that various network topologies and agent heterogeneities have significant impacts on agent learning behaviors in the proposed framework, and under certain circumstances, high levels of cooperation can be achieved among the agents.

Demeter, persephone, and the search for emergence in agent-based models.

DOE Office of Scientific and Technical Information (OSTI.GOV)

North, M. J.; Howe, T. R.; Collier, N. T.

2006-01-01

In Greek mythology, the earth goddess Demeter was unable to find her daughter Persephone after Persephone was abducted by Hades, the god of the underworld. Demeter is said to have embarked on a long and frustrating, but ultimately successful, search to find her daughter. Unfortunately, long and frustrating searches are not confined to Greek mythology. In modern times, agent-based modelers often face similar troubles when searching for agents that are to be to be connected to one another and when seeking appropriate target agents while defining agent behaviors. The result is a 'search for emergence' in that many emergent ormore » potentially emergent behaviors in agent-based models of complex adaptive systems either implicitly or explicitly require search functions. This paper considers a new nested querying approach to simplifying such agent-based modeling and multi-agent simulation search problems.« less

Fluid extraction using carbon dioxide and organophosphorus chelating agents

DOEpatents

Smart, N.G.; Wai, C.M.; Lin, Y.; Kwang, Y.H.

1998-11-24

Methods for extracting metalloid and metal species from a solid or liquid material by exposing the material to a fluid solvent, particularly supercritical CO{sub 2}, and a chelating agent are described. The chelating agent forms a chelate with the species, the chelate being soluble in the fluid to allow removal of the species from the material. In preferred embodiments the extraction solvent is supercritical CO{sub 2} and the chelating agent comprises an organophosphorous chelating agent, particularly sulfur-containing organophosphorous chelating agents, including mixtures of chelating agents. Examples of chelating agents include monothiophosphinic acid, di-thiophosphinic acid, phosphine sulfite, phosphorothioic acid, and mixtures thereof. The method provides an environmentally benign process for removing metal and metalloids from industrial waste solutions, particularly acidic solutions. Both the chelate and the supercritical fluid can be regenerated and the contaminant species recovered to provide an economic, efficient process. 1 fig.

Fluid extraction using carbon dioxide and organophosphorus chelating agents

DOEpatents

Smart, Neil G.; Wai, Chien M.; Lin, Yuehe; Kwang, Yak Hwa

1998-01-01

Methods for extracting metalloid and metal species from a solid or liquid material by exposing the material to a fluid solvent, particularly supercritical CO.sub.2, and a chelating agent are described. The chelating agent forms a chelate with the species, the chelate being soluble in the fluid to allow removal of the species from the material. In preferred embodiments the extraction solvent is supercritical CO.sub.2 and the chelating agent comprises an organophosphorous chelating agent, particularly sulfur-containing organophosphorous chelating agents, including mixtures of chelating agents. Examples of chelating agents include monothiophosphinic acid, di-thiophosphinic acid, phosphine sulfite, phosphorothioic acid, and mixtures thereof. The method provides an environmentally benign process for removing metal and metalloids from industrial waste solutions, particularly acidic solutions. Both the chelate and the supercritical fluid can be regenerated and the contaminant species recovered to provide an economic, efficient process.

How to justify enforcing a Ulysses contract when Ulysses is competent to refuse.

PubMed

Davis, John K

2008-03-01

Sometimes the mentally ill have sufficient mental capacity to refuse treatment competently, and others have a moral duty to respect their refusal. However, those with episodic mental disorders may wish to precommit themselves to treatment, using Ulysses contracts known as "mental health advance directives." How can health care providers justify enforcing such contracts over an agent's current, competent refusal? I argue that providers respect an agent's autonomy not retrospectively--by reference to his or her past wishes-and not merely synchronically--so that the agent gets what he or she wants right now-but diachronically and prospectively, acting so that the agent can shape his or her circumstances as the agent wishes over time, for the agent will experience the consequences of providers' actions over time. Mental health directives accomplish this, so they are a way of respecting the agent's autonomy even when providers override the agent's current competent refusal.

Ultrasound Contrast Agents

NASA Astrophysics Data System (ADS)

Cachard, Christian; Basset, Olivier

While the use of contrast agents in other imaging modalities (X ray, MRI, PET, …) has been routinely accepted for many years, the development and commercialization of contrast agents designed specifically for ultrasound imaging has occurred only very recently. As in the other imaging modalities, the injection of contrast agents during an ultrasound examination is intended to facilitate the detection and diagnosis of specific pathologies. Contrast agents efficiency is based on the backscattering of ultrasound by microbubbles. These microparticules are intravenously injected in the blood flow. After an introduction and generalities on ultrasound contrast agents (UCA) the microbubble physics in an acoustic field will be developed. Second, physics characteristics of contrast agents will be compared (bubbles with or without shell, gas nature, size distribution). Influence of acoustic pressure on the behaviour of the microparticules (linear, non linear and destruction) will be discussed. Finally, a review of specific imaging adapted to contrast agent properties as harmonic imaging, pulse inversion imaging will be presented.

Daphnia swarms: from single agent dynamics to collective vortex formation

NASA Astrophysics Data System (ADS)

Ordemann, Anke; Balazsi, Gabor; Caspari, Elizabeth; Moss, Frank

2003-05-01

Swarm theories have become fashionable in theoretical physics over the last decade. They span the range of interactions from individual agents moving in a mean field to coherent collective motions of large agent populations, such as vortex-swarming. But controlled laboratory tests of these theories using real biological agents have been problematic due primarily to poorly known agent-agent interactions (in the case of e.g. bacteria and slime molds) or the large swarm size (e.g. for flocks of birds and schools of fish). Moreover, the entire range of behaviors from single agent interactions to collective vortex motions of the swarm have here-to-fore not been observed with a single animal. We present the results of well defined experiments with the zooplankton Daphnia in light fields showing this range of behaviors. We interpret our results with a theory of the motions of self-propelled agents in a field.

Manipulating Scrip Systems: Sybils and Collusion

NASA Astrophysics Data System (ADS)

Kash, Ian A.; Friedman, Eric J.; Halpern, Joseph Y.

Game-theoretic analyses of distributed and peer-to-peer systems typically use the Nash equilibrium solution concept, but this explicitly excludes the possibility of strategic behavior involving more than one agent. We examine the effects of two types of strategic behavior involving more than one agent, sybils and collusion, in the context of scrip systems where agents provide each other with service in exchange for scrip. Sybils make an agent more likely to be chosen to provide service, which generally makes it harder for agents without sybils to earn money and decreases social welfare. Surprisingly, in certain circumstances it is possible for sybils to make all agents better off. While collusion is generally bad, in the context of scrip systems it actually tends to make all agents better off, not merely those who collude. These results also provide insight into the effects of allowing agents to advertise and loan money.

Social Cognition Unbound: Insights Into Anthropomorphism and Dehumanization.

PubMed

Waytz, Adam; Epley, Nicholas; Cacioppo, John T

2010-02-01

People conceive of wrathful gods, fickle computers, and selfish genes, attributing human characteristics to a variety of supernatural, technological, and biological agents. This tendency to anthropomorphize nonhuman agents figures prominently in domains ranging from religion to marketing to computer science. Perceiving an agent to be humanlike has important implications for whether the agent is capable of social influence, accountable for its actions, and worthy of moral care and consideration. Three primary factors-elicited agent knowledge, sociality motivation, and effectance motivation-appear to account for a significant amount of variability in anthropomorphism. Identifying these factors that lead people to see nonhuman agents as humanlike also sheds light on the inverse process of dehumanization, whereby people treat human agents as animals or objects. Understanding anthropomorphism can contribute to a more expansive view of social cognition that applies social psychological theory to a wide variety of both human and nonhuman agents.

Social Cognition Unbound: Insights Into Anthropomorphism and Dehumanization

PubMed Central

Waytz, Adam; Epley, Nicholas; Cacioppo, John T.

2014-01-01

People conceive of wrathful gods, fickle computers, and selfish genes, attributing human characteristics to a variety of supernatural, technological, and biological agents. This tendency to anthropomorphize nonhuman agents figures prominently in domains ranging from religion to marketing to computer science. Perceiving an agent to be humanlike has important implications for whether the agent is capable of social influence, accountable for its actions, and worthy of moral care and consideration. Three primary factors—elicited agent knowledge, sociality motivation, and effectance motivation—appear to account for a significant amount of variability in anthropomorphism. Identifying these factors that lead people to see nonhuman agents as humanlike also sheds light on the inverse process of dehumanization, whereby people treat human agents as animals or objects. Understanding anthropomorphism can contribute to a more expansive view of social cognition that applies social psychological theory to a wide variety of both human and nonhuman agents. PMID:24839358

Multi-agent Reinforcement Learning Model for Effective Action Selection

NASA Astrophysics Data System (ADS)

Youk, Sang Jo; Lee, Bong Keun

Reinforcement learning is a sub area of machine learning concerned with how an agent ought to take actions in an environment so as to maximize some notion of long-term reward. In the case of multi-agent, especially, which state space and action space gets very enormous in compared to single agent, so it needs to take most effective measure available select the action strategy for effective reinforcement learning. This paper proposes a multi-agent reinforcement learning model based on fuzzy inference system in order to improve learning collect speed and select an effective action in multi-agent. This paper verifies an effective action select strategy through evaluation tests based on Robocop Keep away which is one of useful test-beds for multi-agent. Our proposed model can apply to evaluate efficiency of the various intelligent multi-agents and also can apply to strategy and tactics of robot soccer system.

Dual Contrast - Magnetic Resonance Fingerprinting (DC-MRF): A Platform for Simultaneous Quantification of Multiple MRI Contrast Agents.

PubMed

Anderson, Christian E; Donnola, Shannon B; Jiang, Yun; Batesole, Joshua; Darrah, Rebecca; Drumm, Mitchell L; Brady-Kalnay, Susann M; Steinmetz, Nicole F; Yu, Xin; Griswold, Mark A; Flask, Chris A

2017-08-16

Injectable Magnetic Resonance Imaging (MRI) contrast agents have been widely used to provide critical assessments of disease for both clinical and basic science imaging research studies. The scope of available MRI contrast agents has expanded over the years with the emergence of molecular imaging contrast agents specifically targeted to biological markers. Unfortunately, synergistic application of more than a single molecular contrast agent has been limited by MRI's ability to only dynamically measure a single agent at a time. In this study, a new Dual Contrast - Magnetic Resonance Fingerprinting (DC - MRF) methodology is described that can detect and independently quantify the local concentration of multiple MRI contrast agents following simultaneous administration. This "multi-color" MRI methodology provides the opportunity to monitor multiple molecular species simultaneously and provides a practical, quantitative imaging framework for the eventual clinical translation of molecular imaging contrast agents.

Collective circular motion in synchronized and balanced formations with second-order rotational dynamics

NASA Astrophysics Data System (ADS)

Jain, Anoop; Ghose, Debasish

2018-01-01

This paper considers collective circular motion of multi-agent systems in which all the agents are required to traverse different circles or a common circle at a prescribed angular velocity. It is required to achieve these collective motions with the heading angles of the agents synchronized or balanced. In synchronization, the agents and their centroid have a common velocity direction, while in balancing, the movement of agents causes the location of the centroid to become stationary. The agents are initially considered to move at unit speed around individual circles at different angular velocities. It is assumed that the agents are subjected to limited communication constraints, and exchange relative information according to a time-invariant undirected graph. We present suitable feedback control laws for each of these motion coordination tasks by considering a second-order rotational dynamics of the agent. Simulations are given to illustrate the theoretical findings.

Assessment of fetal inflammatory syndrome by "classical" markers in the management of preterm labor: a possible lesson from metabolomics and system biology.

PubMed

Ferrazzi, Enrico; Muggiasca, Maria Luisa; Fabbri, Elisa; Fontana, Paola; Castoldi, Francesco; Lista, Gianluca; Primerano, Liviana; Livio, Stefania; Di Francesco, Stefania

2012-10-01

There exists a huge gap between protocols issued by scientific bodies and evidence derived by system biology studies on the multifactorial origin of threatened preterm delivery and their different associations with neonatal outcome. The objective of this prospective study was the analysis obstetrical and neonatal outcome in a cohort of pregnant patients treated for the risk of preterm delivery according to maternal and fetal assessment determined by amniotic fluid samples. Methods. Threatened preterm delivery and premature rupture of membranes between 24 + 1 and 32 + 6 weeks of gestation were treated by prolonged tocolytic regimens and if necessary by antibiotics for maternal infections when intra-amniotic inflammation (IAI) was excluded on the basis of negative white blood cell count in the amniotic fluid, or opposite, by delivery after a course of betamethasone and 48 hours maintenance tocolysis. Twenty-three cases were compared with 22 historical controls treated by the same teams according to the 48 hours treat and wait criteria. In addition to this, cases with normal and abnormal amniotic fluid white blood cell were compared. Results. Maternal and fetal conditions at admission were not significantly different between the study and control cohort for all maternal and fetal variables. Clinical indices were significantly improved as regard to latency from admission to delivery, number of newborns admitted to neonatal intensive care unit and length of stay in neonatal intensive care unit. Not any perinatal death or sepsis occurred in the study cohort. Overall, improved neonatal outcomes were observed in the study cohort. Composite major neonatal eventful outcomes occurred in 26% of cases vs. 50% in controls. The limited number of cases was not powered enough to reach a statistical significance for these variables. Continued tocolysis on demand and full regimen of mono or combined antibiotic regimen for maternal infection achieved significantly longer delay between admission to delivery with improved in neonatal outcome in cases negative for IAI: only 2 of 14 newborns suffered of major neonatal complications vs. 4 of 9 newborns delivered for IAI. Conclusions. Fetuses without IAI can be treated conservatively and their stay in utero prolonged without harm. However, we confirmed that when IAI is already active in utero a worse neonatal outcome is already partly predetermined. These positive findings must be interpreted with cautions given the limited number of cases considered by this study.

Reliable Prescreening of Candidate NerveAgent Prophylaxes via 3D QSAR

DTIC Science & Technology

2005-12-31

recognize and predict prospective toxicity among covalent -binding AChE inhibitors of potential application to nerve agent prophylaxis and...is below since many authors do not follow the 200 word limit 14. SUBJECT TERMS nerve agents , acetylcholinesterase, prophylaxis, QSAR, virtual...Report: Reliable Prescreening of Candidate NerveAgent Prophylaxes via 3D QSAR Report Title ABSTRACT Organophosphorus (OP) nerve agents are among the

Exploration of Force Transition in Stability Operations Using Multi-Agent Simulation

DTIC Science & Technology

2006-09-01

risk, mission failure risk, and time in the context of the operational threat environment. The Pythagoras Multi-Agent Simulation and Data Farming...NUMBER OF PAGES 173 14. SUBJECT TERMS Stability Operations, Peace Operations, Data Farming, Pythagoras , Agent- Based Model, Multi-Agent Simulation...the operational threat environment. The Pythagoras Multi-Agent Simulation and Data Farming techniques are used to investigate force-level

Rich or poor: Who should pay higher tax rates?

NASA Astrophysics Data System (ADS)

Murilo Castro de Oliveira, Paulo

2017-08-01

A dynamic agent model is introduced with an annual random wealth multiplicative process followed by taxes paid according to a linear wealth-dependent tax rate. If poor agents pay higher tax rates than rich agents, eventually all wealth becomes concentrated in the hands of a single agent. By contrast, if poor agents are subject to lower tax rates, the economic collective process continues forever.

Population dynamics and impacts of the red-headed leafy spurge stem borer on leafy spurge (Euphorbia esula)

Treesearch

Robert A. Progar; George Markin; Joseph Milan; Tom Barbouletos; Matthew J. Rinella

2011-01-01

We evaluated the efficacy of the biological control agent, red-headed leafy spurge stem borer, against the nonnative invasive plant leafy spurge. Our three treatments were release of the biological control agent into uncaged plots, release of the biological control agent into plots caged to prevent agent escape, and control plots caged to prevent agent entry. These...

17 CFR 279.4 - Form ADV-NR, appointment of agent for service of process by non-resident general partner and non...

Code of Federal Regulations, 2010 CFR

2010-04-01

... 17 Commodity and Securities Exchanges 3 2010-04-01 2010-04-01 false Form ADV-NR, appointment of agent for service of process by non-resident general partner and non-resident managing agent of an... agent for service of process by non-resident general partner and non-resident managing agent of an...

Maintaining Limited-Range Connectivity Among Second-Order Agents

DTIC Science & Technology

2016-07-07

we consider ad-hoc networks of robotic agents with double integrator dynamics. For such networks, the connectivity maintenance problems are: (i) do...hoc networks of mobile autonomous agents. This loose ter- minology refers to groups of robotic agents with limited mobility and communica- tion...connectivity can be preserved. 3.1. Networks of robotic agents with second-order dynamics and the connectivity maintenance problem. We begin by

Influence of Selected Personal Characteristics and County Situational Factors on Time Allocated to Dairy Subjects by Extension Agents in Selected Tennessee Counties.

ERIC Educational Resources Information Center

Northcutt, Sherwin Dean; And Others

The study deals with various predictors of time spent on dairy subjects by Extension agents and predictors of contacts made by agents with dairy clientele. Purposes were to determine the relationships, if any, between various independent variables and groups of independent variables (agents' background and training, county dairy situation, agents'…

How do ensembles occupy space?

NASA Astrophysics Data System (ADS)

Daffertshofer, A.

2008-04-01

To find an answer to the title question, an attractiveness function between agents and locations is introduced yielding a phenomenological but generic model for the search for optimal distributions of agents over space. Agents can be seen as, e.g., members of biological populations like colonies of bacteria, swarms, and so on. The global attractiveness between agents and locations is maximized causing (self-propelled) `motion' of agents and, eventually, distinct distributions of agents over space. At the same token spontaneous changes or `decisions' are realized via competitions between agents as well as between locations. Hence, the model's solutions can be considered a sequence of decisions of agents during their search for a proper location. Depending on initial conditions both optimal as well as suboptimal configurations can be reached. For the latter early decision-making are important for avoiding possible conflicts: if the proper moment is missed, then only a few agents can find an optimal solution. Indeed, there is a delicate interplay between the values of the attractiveness function and the constraints as can be expressed by distinct terms of a potential function containing different Lagrange parameters. The model should be viewed as a top-down approach as it describes the dynamics of order parameters, i.e. macroscopic variables that reflect affiliations between agents and locations. The dynamics, however, is modified via so-called cost functions that are interpreted in terms of affinity levels. This interpretation can be seen as an original step towards an understanding of the dynamics at the underlying microscopic level. When focusing on the agent, one may say that the dynamics of an order parameter shows the evolution of an agent's intrinsic `map' for solving the problem of space occupation. Importantly, the dynamics does not necessarily distinguish between evolving (or moving) agents and evolving (or moving) locations though agents are more likely to be actors than the locations. Put differently, an order parameter describes an internal map which is linked to the expectation of an agent to find a certain location. Owing to the dynamical representation, we can therefore follow up the change of these maps over time leading from uncertainty to certainty.

Skin-derived dendritic cells acquire and degrade the scrapie agent following in vitro exposure

PubMed Central

Mohan, Joanne; Hopkins, John; Mabbott, Neil A

2005-01-01

The accumulation of the scrapie agent in lymphoid tissues following inoculation via the skin is critical for efficient neuroinvasion, but how the agent is initially transported from the skin to the draining lymph node is not known. Langerhans cells (LCs) are specialized antigen-presenting cells that continually sample their microenvironment within the epidermis and transport captured antigens to draining lymph nodes. We considered LCs probable candidates to acquire and transport the scrapie agent after inoculation via the skin. XS106 cells are dendritic cells (DCs) isolated from mouse epidermis with characteristics of mature LC cells. To investigate the potential interaction of LCs with the scrapie agent XS106 cells were exposed to the scrapie agent in vitro. We show that XS106 cells rapidly acquire the scrapie agent following in vitro exposure. In addition, XS106 cells partially degrade the scrapie agent following extended cultivation. These data suggest that LCs might acquire and degrade the scrapie agent after inoculation via the skin, but data from additional experiments demonstrate that this ability could be lost in the presence of lipopolysaccharide or other immunostimulatory molecules. Our studies also imply that LCs would not undergo maturation following uptake of the scrapie agent in the skin, as the expression of surface antigens associated with LC maturation were unaltered following exposure. In conclusion, although LCs or DCs have the potential to acquire the scrapie agent within the epidermis our data suggest it is unlikely that they become activated and stimulated to transport the agent to the draining lymph node. PMID:16108824

Male bladder cancer risk and occupational exposure according to a job-exposure matrix-a case-control study in British Columbia, Canada.

PubMed

Richardson, Kathryn; Band, Pierre R; Astrakianakis, George; Le, Nhu D

2007-12-01

The authors investigated the risk of bladder cancer in association with exposure to over 12 000 occupational chemical agents, complex mixtures, and other substances (hereafter referred to as chemical agents). Adult males diagnosed with cancer between 1983 and 1990 in British Columbia, Canada, were surveyed. Detailed occupational histories and confounding information was provided by a self-administered questionnaire. Cancer controls were matched to bladder cancer cases, resulting in 1062 cases and 8057 controls for the analysis. An extensive United-States-based job-exposure matrix was applied to estimate cumulative exposure to occupational chemical agents. Odds ratios for bladder cancer due to exposure to chemical agents were estimated via conditional logistic regression analyses, adjusted for important confounders. A significantly (P<0.05) increased risk was detected for ever exposure to 635 chemical agents, and 341 chemical agents exhibited a significantly increasing dose-response relationship. Adjustment for multiple comparisons resulted in a subset of 29 chemical agents that continued to show significant results. A principal components analysis classified these 29 chemical agents into five independent groups, distinguished mainly by job. Exposures to these chemical agents were largely due to employment in the logging and construction industries and occupations involving motor vehicles. Consistent results were observed for bladder carcinogens reported in the literature. This study suggests that several specific chemical agents were significantly associated with the risk of bladder cancer. The chemical agents were mainly derivatives or combustion products of fossil fuels. The results corroborate important findings from the literature and document a risk for specific chemical agents not previously reported.

Joint Chemical Agent Detector (JCAD): the future of chemical agent detection

NASA Astrophysics Data System (ADS)

Laljer, Charles E.; Owen, Jeffery L.

2002-06-01

The Joint Chemical Agent Detector (JCAD) will provide state of the art chemical warfare agent detection capability to ground vehicle operators. Intelligence sources estimate that over twenty counties have active chemical weapons programs. The spread of chemical weapons to third world nations, coupled with the potential for US involvement in these areas in an operational or support capacity, increases the probability that the Joint Services may encounter chemical agents and toxic industrial materials anywhere in the world. Currently, fielded chemical agent detectors are bulky, labor intensive, and subject to false readings. No legacy detector is sensitive enough to provide detection and warning of the low dose hazards associated with miosis contamination. The JCAD will provide a small, lightweight chemical agent detector for vehicle interiors, aircraft, individual personnel, shipboard, and fixed site locations. The system provides a common detection components across multi-service platforms. This common detector system will allow the Joint Services to use the same operational and support concept for more efficient utilization of resources. The JCAD will detect, identify, quantify, and warn of the presence of chemical agents prior to onset of miosis. Upon detection of chemical agents, the detector will provide local and remote audible and visual alarms to the operators. Advance warning will provide the vehicle crew with the time necessary to protect themselves from the lethal effects of chemical agents. The JCAD will also be capable of being upgraded to protect against future chemical agent threats. The JCAD will provide the vehicle operators with the warning necessary to survive and fight in a chemical warfare agent threat environment.

Dynamics and Steady States in Excitable Mobile Agent Systems

NASA Astrophysics Data System (ADS)

Peruani, Fernando; Sibona, Gustavo J.

2008-04-01

We study the spreading of excitations in 2D systems of mobile agents where the excitation is transmitted when a quiescent agent keeps contact with an excited one during a nonvanishing time. We show that the steady states strongly depend on the spatial agent dynamics. Moreover, the coupling between exposition time (ω) and agent-agent contact rate (CR) becomes crucial to understand the excitation dynamics, which exhibits three regimes with CR: no excitation for low CR, an excited regime in which the number of quiescent agents (S) is inversely proportional to CR, and, for high CR, a novel third regime, model dependent, where S scales with an exponent ξ-1, with ξ being the scaling exponent of ω with CR.

Virtual agents in a simulated virtual training environment

NASA Technical Reports Server (NTRS)

Achorn, Brett; Badler, Norman L.

1993-01-01

A drawback to live-action training simulations is the need to gather a large group of participants in order to train a few individuals. One solution to this difficulty is the use of computer-controlled agents in a virtual training environment. This allows a human participant to be replaced by a virtual, or simulated, agent when only limited responses are needed. Each agent possesses a specified set of behaviors and is capable of limited autonomous action in response to its environment or the direction of a human trainee. The paper describes these agents in the context of a simulated hostage rescue training session, involving two human rescuers assisted by three virtual (computer-controlled) agents and opposed by three other virtual agents.

Biomaterials for mediation of chemical and biological warfare agents.

PubMed

Russell, Alan J; Berberich, Jason A; Drevon, Geraldine F; Koepsel, Richard R

2003-01-01

Recent events have emphasized the threat from chemical and biological warfare agents. Within the efforts to counter this threat, the biocatalytic destruction and sensing of chemical and biological weapons has become an important area of focus. The specificity and high catalytic rates of biological catalysts make them appropriate for decommissioning nerve agent stockpiles, counteracting nerve agent attacks, and remediation of organophosphate spills. A number of materials have been prepared containing enzymes for the destruction of and protection against organophosphate nerve agents and biological warfare agents. This review discusses the major chemical and biological warfare agents, decontamination methods, and biomaterials that have potential for the preparation of decontamination wipes, gas filters, column packings, protective wear, and self-decontaminating paints and coatings.

Social effects of an anthropomorphic help agent: humans versus computers.

PubMed

David, Prabu; Lu, Tingting; Kline, Susan; Cai, Li

2007-06-01

The purpose of this study was to examine perceptions of fairness of a computer-administered quiz as a function of the anthropomorphic features of the help agent offered within the quiz environment. The addition of simple anthropomorphic cues to a computer help agent reduced the perceived friendliness of the agent, perceived intelligence of the agent, and the perceived fairness of the quiz. These differences were observed only for male anthropomorphic cues, but not for female anthropomorphic cues. The results were not explained by the social attraction of the anthropomorphic agents used in the quiz or by gender identification with the agents. Priming of visual cues provides the best account of the data. Practical implications of the study are discussed.

TACtic- A Multi Behavioral Agent for Trading Agent Competition

NASA Astrophysics Data System (ADS)

Khosravi, Hassan; Shiri, Mohammad E.; Khosravi, Hamid; Iranmanesh, Ehsan; Davoodi, Alireza

Software agents are increasingly being used to represent humans in online auctions. Such agents have the advantages of being able to systematically monitor a wide variety of auctions and then make rapid decisions about what bids to place in what auctions. They can do this continuously and repetitively without losing concentration. To provide a means of evaluating and comparing (benchmarking) research methods in this area the trading agent competition (TAC) was established. This paper describes the design, of TACtic. Our agent uses multi behavioral techniques at the heart of its decision making to make bidding decisions in the face of uncertainty, to make predictions about the likely outcomes of auctions, and to alter the agent's bidding strategy in response to the prevailing market conditions.

13 CFR 120.952 - Fiscal agent.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Loan Program (504) Debenture Sales and Service Agents § 120.952 Fiscal agent. SBA shall appoint a Fiscal Agent to assess the financial markets, minimize the cost of sales, arrange for the production of... performance of the Trustee and the underwriters. ...

13 CFR 120.952 - Fiscal agent.

Code of Federal Regulations, 2011 CFR

2011-01-01

... Loan Program (504) Debenture Sales and Service Agents § 120.952 Fiscal agent. SBA shall appoint a Fiscal Agent to assess the financial markets, minimize the cost of sales, arrange for the production of... performance of the Trustee and the underwriters. ...

30 CFR 250.145 - How do I designate an agent or a local agent?

Code of Federal Regulations, 2012 CFR

2012-07-01

... require you to designate an agent empowered to fulfill your obligations under the Act, the lease, or the... approval a local agent empowered to receive notices and submit requests, applications, notices, or...

30 CFR 250.145 - How do I designate an agent or a local agent?

Code of Federal Regulations, 2014 CFR

2014-07-01

... require you to designate an agent empowered to fulfill your obligations under the Act, the lease, or the... approval a local agent empowered to receive notices and submit requests, applications, notices, or...

30 CFR 250.145 - How do I designate an agent or a local agent?

Code of Federal Regulations, 2013 CFR

2013-07-01

... require you to designate an agent empowered to fulfill your obligations under the Act, the lease, or the... approval a local agent empowered to receive notices and submit requests, applications, notices, or...

Comparison of the clinical efficacy between single-agent and dual-agent concurrent chemoradiotherapy in the treatment of unresectable esophageal squamous cell carcinoma: a multicenter retrospective analysis.

PubMed

Li, Jie; Gong, Youling; Diao, Peng; Huang, Qingmei; Wen, Yixue; Lin, Binwei; Cai, Hongwei; Tian, Honggang; He, Bing; Ji, Lanlan; Guo, Ping; Miao, Jidong; Du, Xiaobo

2018-01-22

Some Chinese patients with esophageal squamous cell carcinomaare often treated with single-agent concurrent chemoradiotherapy. However, no results have been reported from randomized controlled clinical trials comparing single-agent with double-agent concurrent chemoradiotherapy. It therefore remains unclear whether these regimens are equally clinically effective. In this study, we retrospectively analyzed and compared the therapeutic effects of single-agent and double-agent concurrent chemoradiotherapy in patients with unresectable esophageal squamous cell carcinoma. This study enrolled 168 patients who received definitive concurrent chemoradiotherapy for locally advanced unresectable esophageal squamous carcinoma at 10 hospitals between 2010 and 2015. We evaluated survival time and toxicity. The Kaplan-Meier method was used to estimate survival data. The log-rank test was used in univariate analysis A Cox proportional hazards regression model was used to conduct a multivariate analysis of the effects of prognostic factors on survival. In this study, 100 (59.5%) and 68 patients (40.5%) received single-agent and dual-agent combination chemoradiotherapy, respectively. The estimate 5-year progression-free survival (PFS) rate and overall survival (OS) rate of dual-agent therapy was higher than that of single-agent therapy (52.5% and 40.9%, 78.2% and 60.7%, respectively), but there were no significant differences (P = 0.367 and 0.161, respectively). Multivariate analysis showed that sex, age,and radiotherapy dose had no significant effects on OS or PFS. Only disease stage was associated with OS and PFS in the multivariable analysis (P = 0.006 and 0.003, respectively). In dual-agent group, the incidence of acute toxicity and the incidence of 3 and4 grade toxicity were higher than single-agent group. The 5-year PFS and OS rates of dual-agent therapy were higher than those of single-agent concurrent chemoradiotherapy for patients with unresectable esophageal squamous cell carcinoma; however, there were no significant differences in univariate analysis and multivariable analysis. Single-agent concurrent chemotherapy had less toxicity than a double-drug regimen. Therefore, we suggest that single therapis not inferior to dual therapy y. In the future, we aim to confirm our hypothesis through a prospective randomized study.

Conformity-driven agents support ordered phases in the spatial public goods game

NASA Astrophysics Data System (ADS)

Javarone, Marco Alberto; Antonioni, Alberto; Caravelli, Francesco

2016-05-01

We investigate the spatial Public Goods Game in the presence of fitness-driven and conformity-driven agents. This framework usually considers only the former type of agents, i.e., agents that tend to imitate the strategy of their fittest neighbors. However, whenever we study social systems, the evolution of a population might be affected also by social behaviors as conformism, stubbornness, altruism, and selfishness. Although the term evolution can assume different meanings depending on the considered domain, here it corresponds to the set of processes that lead a system towards an equilibrium or a steady state. We map fitness to the agents' payoff so that richer agents are those most imitated by fitness-driven agents, while conformity-driven agents tend to imitate the strategy assumed by the majority of their neighbors. Numerical simulations aim to identify the nature of the transition, on varying the amount of the relative density of conformity-driven agents in the population, and to study the nature of related equilibria. Remarkably, we find that conformism generally fosters ordered cooperative phases and may also lead to bistable behaviors.

Biologic agents for IBD: practical insights.

PubMed

Danese, Silvio; Vuitton, Lucine; Peyrin-Biroulet, Laurent

2015-09-01

Six biologic agents are currently approved for the treatment of IBD: four anti-TNF agents (infliximab, adalimumab, golimumab and certolizumab pegol) and two anti-integrin agents (natalizumab and vedolizumab). In Crohn's disease and ulcerative colitis refractory to standard medications, treatment choice among available biologic agents can be challenging. Several parameters should be taken into account to help physicians through the decision-making process, including the comparative effectiveness and long-term safety profile, availability and labelling in the prescriber's country, international guidelines, and cost, as well as patient preferences (such as the route of administration). Herein, we provide practical insights on the use of biologic agents in IBD. The results of head-to-head trials between biologic agents are eagerly awaited to guide decision-making regarding the choice of first-line biologic agents and to determine whether switching within the same drug class or swapping (switching out of the drug class) is preferable after primary or secondary loss of response to the first biologic agent. In the near future, treatment algorithms might evolve with the launch of new drugs (such as ustekinumab, tofacitinib and etrolizumab) and the increased use of biosimilars.

Nash Equilibrium of Social-Learning Agents in a Restless Multiarmed Bandit Game.

PubMed

Nakayama, Kazuaki; Hisakado, Masato; Mori, Shintaro

2017-05-16

We study a simple model for social-learning agents in a restless multiarmed bandit (rMAB). The bandit has one good arm that changes to a bad one with a certain probability. Each agent stochastically selects one of the two methods, random search (individual learning) or copying information from other agents (social learning), using which he/she seeks the good arm. Fitness of an agent is the probability to know the good arm in the steady state of the agent system. In this model, we explicitly construct the unique Nash equilibrium state and show that the corresponding strategy for each agent is an evolutionarily stable strategy (ESS) in the sense of Thomas. It is shown that the fitness of an agent with ESS is superior to that of an asocial learner when the success probability of social learning is greater than a threshold determined from the probability of success of individual learning, the probability of change of state of the rMAB, and the number of agents. The ESS Nash equilibrium is a solution to Rogers' paradox.

Flotability and flotation separation of polymer materials modulated by wetting agents.

PubMed

Wang, Hui; Wang, Chong-qing; Fu, Jian-gang; Gu, Guo-hua

2014-02-01

The surface free energy, surface tension and contact angles were performed to investigate the properties of wetting agents. Adsorption of wetting agents changes wetting behavior of polymer resins. Flotability of polymer materials modulated by wetting agents was studied, and wetting agents change significantly flotability of polymer materials. The flotability decreases with increasing the concentration of wetting agents, and the wetting ability is lignin sulfonate (LS)>tannic acid (TA)>methylcellulose (MC)>triton X-100 (TX-100) (from strong to weak). There is significant difference in the flotability between polymer resins and plastics due to the presence of additives in the plastics. Flotation separation of two-component and multicomponent plastics was conducted based on the flotability modulated by wetting agents. The two-component mixtures can be efficiently separated using proper wetting agent through simple flotation flowsheet. The multicomponent plastic mixtures can be separated efficiently through multi-stage flotation using TA and LS as wetting agents, and the purity of separated component was above 94%, and the recovery was more than 93%. Copyright © 2013 Elsevier Ltd. All rights reserved.

Gadolinium-Based Contrast Agents for MR Cancer Imaging

PubMed Central

Zhou, Zhuxian; Lu, Zheng-Rong

2013-01-01

Magnetic resonance imaging (MRI) is a clinical imaging modality effective for anatomical and functional imaging of diseased soft tissues, including solid tumors. MRI contrast agents have been routinely used for detecting tumor at an early stage. Gadolinium based contrast agents are the most commonly used contrast agents in clinical MRI. There have been significant efforts to design and develop novel Gd(III) contrast agents with high relaxivity, low toxicity and specific tumor binding. The relaxivity of the Gd(III) contrast agents can be increased by proper chemical modification. The toxicity of Gd(III) contrast agents can be reduced by increasing the agents’ thermodynamic and kinetic stability, as well as optimizing their pharmacokinetic properties. The increasing knowledge in the field of cancer genomics and biology provides an opportunity for designing tumor-specific contrast agents. Various new Gd(III) chelates have been designed and evaluated in animal models for more effective cancer MRI. This review outlines the design and development, physicochemical properties, and in vivo properties of several classes of Gd(III)-based MR contrast agents for tumor imaging. PMID:23047730

Synthesis and characterization of a smart contrast agent sensitive to calcium.

PubMed

Dhingra, Kirti; Maier, Martin E; Beyerlein, Michael; Angelovski, Goran; Logothetis, Nikos K

2008-08-07

A novel first-generation Ca2+ sensitive contrast agent, Gd-DOPTRA has been synthesized and characterized. The agent shows approximately 100% relaxivity enhancement upon addition of Ca2+. The agent is selective and sensitive to Ca2+ also in the presence of Mg2+ and Zn2+. The relaxivity studies carried out in physiological fluids prove the prospects of the agent for in vivo measurements.

Agent Based Fault Tolerance for the Mobile Environment

NASA Astrophysics Data System (ADS)

Park, Taesoon

This paper presents a fault-tolerance scheme based on mobile agents for the reliable mobile computing systems. Mobility of the agent is suitable to trace the mobile hosts and the intelligence of the agent makes it efficient to support the fault tolerance services. This paper presents two approaches to implement the mobile agent based fault tolerant service and their performances are evaluated and compared with other fault-tolerant schemes.

Believable Social and Emotional Agents.

DTIC Science & Technology

1996-05-01

While building tools to support the creation of believable emotional agents, I had to make a number of important design decisions . Before describing...processing systems, it is difficult to give an artist direct control over the emotion - al aspects of the character. By making these decisions explicit, I hope...Woody on “Cheers”). Believable Agents BELIEVABLE SOCIAL AND EMOTIONAL AGENTS 11 Lesson: We don’t want agent architectures that enforce rationality and

Situation awareness-based agent transparency for human-autonomy teaming effectiveness

NASA Astrophysics Data System (ADS)

Chen, Jessie Y. C.; Barnes, Michael J.; Wright, Julia L.; Stowers, Kimberly; Lakhmani, Shan G.

2017-05-01

We developed the Situation awareness-based Agent Transparency (SAT) model to support human operators' situation awareness of the mission environment through teaming with intelligent agents. The model includes the agent's current actions and plans (Level 1), its reasoning process (Level 2), and its projection of future outcomes (Level 3). Human-inthe-loop simulation experiments have been conducted (Autonomous Squad Member and IMPACT) to illustrate the utility of the model for human-autonomy team interface designs. Across studies, the results consistently showed that human operators' task performance improved as the agents became more transparent. They also perceived transparent agents as more trustworthy.

Adapting Price Predictions in TAC SCM

NASA Astrophysics Data System (ADS)

Pardoe, David; Stone, Peter

In agent-based markets, adapting to the behavior of other agents is often necessary for success. When it is not possible to directly model individual competitors, an agent may instead model and adapt to the market conditions that result from competitor behavior. Such an agent could still benefit from reasoning about specific competitor strategies by considering how various combinations of these strategies would impact the conditions being modeled. We present an application of such an approach to a specific prediction problem faced by the agent TacTex-06 in the Trading Agent Competition's Supply Chain Management scenario (TAC SCM).

Multifunctional agents for concurrent imaging and therapy in cardiovascular disease

PubMed Central

McCarthy, Jason R.

2010-01-01

The development of agents for the simultaneous detection and treatment of disease has recently gained significant attention. These multifunctional theranostic agents posses a number of advantages over their monofunctional counterparts, as they potentially allow for the concomitant determination of agent localization, release, and efficacy. Whereas the development of these agents for use in cancers has received the majority of the attention, their use in cardiovascular disease is steadily increasing. As such, this review summarized some of the most poignant recent advances in the development of theranostic agents for the treatment of this class of diseases. PMID:20654664

Nondestructive Intervention to Multi-Agent Systems through an Intelligent Agent

PubMed Central

Han, Jing; Wang, Lin

2013-01-01

For a given multi-agent system where the local interaction rule of the existing agents can not be re-designed, one way to intervene the collective behavior of the system is to add one or a few special agents into the group which are still treated as normal agents by the existing ones. We study how to lead a Vicsek-like flocking model to reach synchronization by adding special agents. A popular method is to add some simple leaders (fixed-headings agents). However, we add one intelligent agent, called ‘shill’, which uses online feedback information of the group to decide the shill's moving direction at each step. A novel strategy for the shill to coordinate the group is proposed. It is strictly proved that a shill with this strategy and a limited speed can synchronize every agent in the group. The computer simulations show the effectiveness of this strategy in different scenarios, including different group sizes, shill speed, and with or without noise. Compared to the method of adding some fixed-heading leaders, our method can guarantee synchronization for any initial configuration in the deterministic scenario and improve the synchronization level significantly in low density groups, or model with noise. This suggests the advantage and power of feedback information in intervention of collective behavior. PMID:23658695

Characterization of chemical agent transport in paints.

PubMed

Willis, Matthew P; Gordon, Wesley; Lalain, Teri; Mantooth, Brent

2013-09-15

A combination of vacuum-based vapor emission measurements with a mass transport model was employed to determine the interaction of chemical warfare agents with various materials, including transport parameters of agents in paints. Accurate determination of mass transport parameters enables the simulation of the chemical agent distribution in a material for decontaminant performance modeling. The evaluation was performed with the chemical warfare agents bis(2-chloroethyl) sulfide (distilled mustard, known as the chemical warfare blister agent HD) and O-ethyl S-[2-(diisopropylamino)ethyl] methylphosphonothioate (VX), an organophosphate nerve agent, deposited on to two different types of polyurethane paint coatings. The results demonstrated alignment between the experimentally measured vapor emission flux and the predicted vapor flux. Mass transport modeling demonstrated rapid transport of VX into the coatings; VX penetrated through the aliphatic polyurethane-based coating (100 μm) within approximately 107 min. By comparison, while HD was more soluble in the coatings, the penetration depth in the coatings was approximately 2× lower than VX. Applications of mass transport parameters include the ability to predict agent uptake, and subsequent long-term vapor emission or contact transfer where the agent could present exposure risks. Additionally, these parameters and model enable the ability to perform decontamination modeling to predict how decontaminants remove agent from these materials. Published by Elsevier B.V.

Not so secret agents: Event-related potentials to semantic roles in visual event comprehension.

PubMed

Cohn, Neil; Paczynski, Martin; Kutas, Marta

2017-12-01

Research across domains has suggested that agents, the doers of actions, have a processing advantage over patients, the receivers of actions. We hypothesized that agents as "event builders" for discrete actions (e.g., throwing a ball, punching) build on cues embedded in their preparatory postures (e.g., reaching back an arm to throw or punch) that lead to (predictable) culminating actions, and that these cues afford frontloading of event structure processing. To test this hypothesis, we compared event-related brain potentials (ERPs) to averbal comic panels depicting preparatory agents (ex. reaching back an arm to punch) that cued specific actions with those to non-preparatory agents (ex. arm to the side) and patients that did not cue any specific actions. We also compared subsequent completed action panels (ex. agent punching patient) across conditions, where we expected an inverse pattern of ERPs indexing the differential costs of processing completed actions asa function of preparatory cues. Preparatory agents evoked a greater frontal positivity (600-900ms) relative to non-preparatory agents and patients, while subsequent completed actions panels following non-preparatory agents elicited a smaller frontal positivity (600-900ms). These results suggest that preparatory (vs. non-) postures may differentially impact the processing of agents and subsequent actions in real time. Copyright © 2017 Elsevier Inc. All rights reserved.

Time-Extended Payoffs for Collectives of Autonomous Agents

NASA Technical Reports Server (NTRS)

Tumer, Kagan; Agogino, Adrian K.

2002-01-01

A collective is a set of self-interested agents which try to maximize their own utilities, along with a a well-defined, time-extended world utility function which rates the performance of the entire system. In this paper, we use theory of collectives to design time-extended payoff utilities for agents that are both aligned with the world utility, and are "learnable", i.e., the agents can readily see how their behavior affects their utility. We show that in systems where each agent aims to optimize such payoff functions, coordination arises as a byproduct of the agents selfishly pursuing their own goals. A game theoretic analysis shows that such payoff functions have the net effect of aligning the Nash equilibrium, Pareto optimal solution and world utility optimum, thus eliminating undesirable behavior such as agents working at cross-purposes. We then apply collective-based payoff functions to the token collection in a gridworld problem where agents need to optimize the aggregate value of tokens collected across an episode of finite duration (i.e., an abstracted version of rovers on Mars collecting scientifically interesting rock samples, subject to power limitations). We show that, regardless of the initial token distribution, reinforcement learning agents using collective-based payoff functions significantly outperform both natural extensions of single agent algorithms and global reinforcement learning solutions based on "team games".

Discovery of Clinically Approved Agents That Promote Suppression of Cystic Fibrosis Transmembrane Conductance Regulator Nonsense Mutations.

PubMed

Mutyam, Venkateshwar; Du, Ming; Xue, Xiaojiao; Keeling, Kim M; White, E Lucile; Bostwick, J Robert; Rasmussen, Lynn; Liu, Bo; Mazur, Marina; Hong, Jeong S; Falk Libby, Emily; Liang, Feng; Shang, Haibo; Mense, Martin; Suto, Mark J; Bedwell, David M; Rowe, Steven M

2016-11-01

Premature termination codons (PTCs) in the cystic fibrosis transmembrane conductance regulator (CFTR) gene cause cystic fibrosis (CF). Several agents are known to suppress PTCs but are poorly efficacious or toxic. To determine whether there are clinically available agents that elicit translational readthrough and improve CFTR function sufficient to confer therapeutic benefit to patients with CF with PTCs. Two independent screens, firefly luciferase and CFTR-mediated transepithelial chloride conductance assay, were performed on a library of 1,600 clinically approved compounds using fisher rat thyroid cells stably transfected with stop codons. Select agents were further evaluated using secondary screening assays including short circuit current analysis on primary cells from patients with CF. In addition, the effect of CFTR modulators (ivacaftor) was tested in combination with the most efficacious agents. From the primary screen, 48 agents were selected as potentially active. Following confirmatory tests in the transepithelial chloride conductance assay and prioritizing agents based on favorable pharmacologic properties, eight agents were advanced for secondary screening. Ivacaftor significantly increased short circuit current following forskolin stimulation in cells treated with pyranoradine tetraphosphate, potassium p-aminobenzoate, and escin as compared with vehicle control. Escin, an herbal agent, consistently induced readthrough activity as demonstrated by enhanced CFTR expression and function in vitro. Clinically approved drugs identified as potential readthrough agents, in combination with ivacaftor, may induce nonsense suppression to restore therapeutic levels of CFTR function. One or more agents may be suitable to advance to human testing.

Software agents and the route to the information economy.

PubMed

Kephart, Jeffrey O

2002-05-14

Humans are on the verge of losing their status as the sole economic species on the planet. In private laboratories and in the Internet laboratory, researchers and developers are creating a variety of autonomous economically motivated software agents endowed with algorithms for maximizing profit or utility. Many economic software agents will function as miniature businesses, purchasing information inputs from other agents, combining and refining them into information goods and services, and selling them to humans or other agents. Their mutual interactions will form the information economy: a complex economic web of information goods and services that will adapt to the ever-changing needs of people and agents. The information economy will be the largest multiagent system ever conceived and an integral part of the world's economy. I discuss a possible route toward this vision, beginning with present-day Internet trends suggesting that agents will charge one another for information goods and services. Then, to establish that agents can be competent price setters, I describe some laboratory experiments pitting software bidding agents against human bidders. The agents' superior performance suggests they will be used on a broad scale, which in turn suggests that interactions among agents will become frequent and significant. How will this affect macroscopic economic behavior? I describe some interesting phenomena that my colleagues and I have observed in simulations of large populations of automated buyers and sellers, such as price war cycles. I conclude by discussing fundamental scientific challenges that remain to be addressed as we journey toward the information economy.

Moral actor, selfish agent.

PubMed

Frimer, Jeremy A; Schaefer, Nicola K; Oakes, Harrison

2014-05-01

People are motivated to behave selfishly while appearing moral. This tension gives rise to 2 divergently motivated selves. The actor-the watched self-tends to be moral; the agent-the self as executor-tends to be selfish. Three studies present direct evidence of the actor's and agent's distinct motives. To recruit the self-as-actor, we asked people to rate the importance of various goals. To recruit the self-as-agent, we asked people to describe their goals verbally. In Study 1, actors claimed their goals were equally about helping the self and others (viz., moral); agents claimed their goals were primarily about helping the self (viz., selfish). This disparity was evident in both individualist and collectivist cultures, attesting to the universality of the selfish agent. Study 2 compared actors' and agents' motives to those of people role-playing highly prosocial or selfish exemplars. In content (Study 2a) and in the impressions they made on an outside observer (Study 2b), actors' motives were similar to those of the prosocial role-players, whereas agents' motives were similar to those of the selfish role-players. Study 3 accounted for the difference between the actor and agent: Participants claimed that their agent's motives were the more realistic and that their actor's motives were the more idealistic. The selfish agent/moral actor duality may account for why implicit and explicit measures of the same construct diverge, and why feeling watched brings out the better angels of human nature.

Preparation and mechanism analysis of an environment-friendly maize seed coating agent.

PubMed

Zeng, Defang; Fan, Zhao; Tian, Xu; Wang, Wenjin; Zhou, Mingchun; Li, Haochuan

2018-06-01

Traditional seed coating agents often contain toxic ingredients, which contaminate the environment and threaten human health. This paper expounds a method of preparing a novel environment-friendly seed coating agent for maize and researches its mechanism of action. The natural polysaccharide polymer, which is the main active ingredient of this environment-friendly seed coating agent, has the characteristics of innocuity and harmlessness, and it can replace the toxic ingredients used in traditional seed coating agents. This environment-friendly seed coating agent for maize was mainly made up of the natural polysaccharide polymer and other additives. The field trials results showed that the control efficacy of Helminthosporium maydis came to 93.72%, the anti-feeding rate of cutworms came to 81.29%, and the maize yield was increased by 17.75%. Besides, the LD 50 value (half the lethal dose in rats) of this seed coating agent was 10 times higher than that of the traditional seed coating agents. This seed coating agent could improve the activity of plant protective enzymes (peroxidase, catalase and superoxidase dismutase) and increase the chlorophyll content. This seed coating agent has four characteristics of disease prevention, desinsectization, increasing yield and safety. Results of mechanism analyses showed that this seed coating agent could enhance disease control effectiveness by improving plant protective enzymes activity and increase maize yield by improving chlorophyll content. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

A real-time architecture for time-aware agents.

PubMed

Prouskas, Konstantinos-Vassileios; Pitt, Jeremy V

2004-06-01

This paper describes the specification and implementation of a new three-layer time-aware agent architecture. This architecture is designed for applications and environments where societies of humans and agents play equally active roles, but interact and operate in completely different time frames. The architecture consists of three layers: the April real-time run-time (ART) layer, the time aware layer (TAL), and the application agents layer (AAL). The ART layer forms the underlying real-time agent platform. An original online, real-time, dynamic priority-based scheduling algorithm is described for scheduling the computation time of agent processes, and it is shown that the algorithm's O(n) complexity and scalable performance are sufficient for application in real-time domains. The TAL layer forms an abstraction layer through which human and agent interactions are temporally unified, that is, handled in a common way irrespective of their temporal representation and scale. A novel O(n2) interaction scheduling algorithm is described for predicting and guaranteeing interactions' initiation and completion times. The time-aware predicting component of a workflow management system is also presented as an instance of the AAL layer. The described time-aware architecture addresses two key challenges in enabling agents to be effectively configured and applied in environments where humans and agents play equally active roles. It provides flexibility and adaptability in its real-time mechanisms while placing them under direct agent control, and it temporally unifies human and agent interactions.

A Methodology For Developing an Agent Systems Reference Architecture

DTIC Science & Technology

2010-05-01

agent framworks , we create an abstraction noting similarities and differences. The differences are documented as points of variation. The result...situated in the physical en- vironment. Addressing how conceptual components of an agent system is beneficial to agent system architects, developers, and

A Multi-Agent System for Intelligent Online Education.

ERIC Educational Resources Information Center

O'Riordan, Colm; Griffith, Josephine

1999-01-01

Describes the system architecture of an intelligent Web-based education system that includes user modeling agents, information filtering agents for automatic information gathering, and the multi-agent interaction. Discusses information management; user interaction; support for collaborative peer-peer learning; implementation; testing; and future…

Heat-resistant agent used for control sand of steam huff and puff heavy oil well

NASA Astrophysics Data System (ADS)

Zhang, F. S.; Liu, G. L.; Lu, Y. J.; Xiong, X. C.; Ma, J. H.; Su, H. M.

2018-01-01

Heat-resistant agent containing hydroxymethyl group was synthesized from coal tar, which has similar structure with phenolic resin and could improve the heat resistance of phenolic resin sand control agent. The results showed that the heat resistance of the sand control agent was improved by adding 10% to 30% heat-resistant agent, after 280°C high temperature treatment for 7d, the compressive strength of consolidated core was increased to more than 5MPa. The compressive strength of consolidation core was not decreased after immersion in formation water, crude oil, acid or alkaline medium, which showed good resistance to medium immersion. The sand control agent had small core damage and the core permeability damage ratio of sand control agent consolidation was only 18.7%.

Formal Modeling of Multi-Agent Systems using the Pi-Calculus and Epistemic Logic

NASA Technical Reports Server (NTRS)

Rorie, Toinette; Esterline, Albert

1998-01-01

Multi-agent systems have become important recently in computer science, especially in artificial intelligence (AI). We allow a broad sense of agent, but require at least that an agent has some measure of autonomy and interacts with other agents via some kind of agent communication language. We are concerned in this paper with formal modeling of multi-agent systems, with emphasis on communication. We propose for this purpose to use the pi-calculus, an extension of the process algebra CCS. Although the literature on the pi-calculus refers to agents, the term is used there in the sense of a process in general. It is our contention, however, that viewing agents in the AI sense as agents in the pi-calculus sense affords significant formal insight. One formalism that has been applied to agents in the AI sense is epistemic logic, the logic of knowledge. The success of epistemic logic in computer science in general has come in large part from its ability to handle concepts of knowledge that apply to groups. We maintain that the pi-calculus affords a natural yet rigorous means by which groups that are significant to epistemic logic may be identified, encapsulated, structured into hierarchies, and restructured in a principled way. This paper is organized as follows: Section 2 introduces the pi-calculus; Section 3 takes a scenario from the classical paper on agent-oriented programming [Sh93] and translates it into a very simple subset of the n-calculus; Section 4 then shows how more sophisticated features of the pi-calculus may bc brought into play; Section 5 discusses how the pi-calculus may be used to define groups for epistemic logic; and Section 6 is the conclusion.

Human Carboxylesterase 1 Stereoselectively Binds the Nerve Agent Cyclosarin and Spontaneously Hydrolyzes the Nerve Agent Sarin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hemmert, Andrew C.; Otto, Tamara C.; Wierdl, Monika

Organophosphorus (OP) nerve agents are potent toxins that inhibit cholinesterases and produce a rapid and lethal cholinergic crisis. Development of protein-based therapeutics is being pursued with the goal of preventing nerve agent toxicity and protecting against the long-term side effects of these agents. The drug-metabolizing enzyme human carboxylesterase 1 (hCE1) is a candidate protein-based therapeutic because of its similarity in structure and function to the cholinesterase targets of nerve agent poisoning. However, the ability of wild-type hCE1 to process the G-type nerve agents sarin and cyclosarin has not been determined. We report the crystal structure of hCE1 in complex withmore » the nerve agent cyclosarin. We further use stereoselective nerve agent analogs to establish that hCE1 exhibits a 1700- and 2900-fold preference for the P{sub R} enantiomers of analogs of soman and cyclosarin, respectively, and a 5-fold preference for the P{sub S} isomer of a sarin analog. Finally, we show that for enzyme inhibited by racemic mixtures of bona fide nerve agents, hCE1 spontaneously reactivates in the presence of sarin but not soman or cyclosarin. The addition of the neutral oxime 2,3-butanedione monoxime increases the rate of reactivation of hCE1 from sarin inhibition by more than 60-fold but has no effect on reactivation with the other agents examined. Taken together, these data demonstrate that hCE1 is only reactivated after inhibition with the more toxic P{sub S} isomer of sarin. These results provide important insights toward the long-term goal of designing novel forms of hCE1 to act as protein-based therapeutics for nerve agent detoxification.« less

Can an agent’s false belief be corrected by an appropriate communication? Psychological reasoning in 18-month-old infants

PubMed Central

Song, Hyun-joo; Onishi, Kristine H.; Baillargeon, Renée; Fisher, Cynthia

2008-01-01

Do 18-month-olds understand that an agent’s false belief can be corrected by an appropriate, though not an inappropriate, communication? In Experiment 1, infants watched a series of events involving two agents, a ball, and two containers: a box and a cup. To start, agent1 played with the ball and then hid it in the box, while agent2 looked on. Next, in agent1’s absence, agent2 moved the ball from the box to the cup. When agent1 returned, agent2 told her “The ball is in the cup!” (informative-intervention condition) or “I like the cup!” (uninformative-intervention condition). During test, agent1 reached for either the box (box event) or the cup (cup event). In the informative-intervention condition, infants who saw the box event looked reliably longer than those who saw the cup event; in the uninformative-intervention condition, the reverse pattern was found. These results suggest that infants expected agent1’s false belief about the ball’s location to be corrected when she was told “The ball is in the cup!”, but not “I like the cup!”. In Experiment 2, agent2 simply pointed to the ball’s new location, and infants again expected agent1’s false belief to be corrected. These and control results provide additional evidence that infants in the second year of life can attribute false beliefs to agents. In addition, the results suggest that by 18 months of age infants expect agents’ false beliefs to be corrected by relevant communications involving words or gestures. PMID:18976745

Analysis of Nerve Agent Metabolites from Hair for Long-Term Verification of Nerve Agent Exposure

DTIC Science & Technology

2016-05-09

Analysis of Nerve Agent Metabolites from Hair for Long-Term Verification of Nerve Agent Exposure Amanda S. Appel,† John H. McDonough,‡ Joseph D...feasible. In this study, hair was evaluated as a long-term repository of nerve agent hydrolysis products. Pinacolyl methylphosphonic acid (PMPA...hydrolysis product of soman) and isopropyl methylphosphonic acid (IMPA; hydrolysis product of sarin) were extracted from hair samples with N,N

Can an Agent's False Belief Be Corrected by an Appropriate Communication? Psychological Reasoning in 18-Month-Old Infants

ERIC Educational Resources Information Center

Song, Hyun-joo; Onishi, Kristine H.; Baillargeon, Renee; Fisher, Cynthia

2008-01-01

Do 18-month-olds understand that an agent's false belief can be corrected by an appropriate, though not an inappropriate, communication? In Experiment 1, infants watched a series of events involving two agents, a ball, and two containers: a box and a cup. To start, agent 1 played with the ball and then hid it in the box, while agent 2 looked on.…

A Model of Human Teamwork for Agent-Assisted Search Operations

DTIC Science & Technology

2008-04-01

agent technology in providing effective team assistance , better understanding of robust human-agent teamwork is crucial. The goal of our research project...to various unexpected events. In order to fulfil the promise of agent technology in providing effective team assistance , better understanding of...distributed decision making. In Command and Control Research and Technology Symposium, 2004. A MODEL OF AGENT- ASSISTED SEARCH OPERATIONS 20 - 20 PUB REF NBR (e.g. RTO-MP-IST-999)

Collaborative Information Agents on the World Wide Web

NASA Technical Reports Server (NTRS)

Chen, James R.; Mathe, Nathalie; Wolfe, Shawn; Koga, Dennis J. (Technical Monitor)

1998-01-01

In this paper, we present DIAMS, a system of distributed, collaborative information agents which help users access, collect, organize, and exchange information on the World Wide Web. Personal agents provide their owners dynamic displays of well organized information collections, as well as friendly information management utilities. Personal agents exchange information with one another. They also work with other types of information agents such as matchmakers and knowledge experts to facilitate collaboration and communication.

Harnessing the Power of Collaborative Relationships to Improve National Preparedness and Responsiveness

DTIC Science & Technology

2011-09-01

to their history of interaction and sharing worldviews. Agents respond to both external pressures (from environment or other agents , e.g,. leaders...hierarchically, but rather by interaction among heterogeneous agents and across agent networks. They go on to note that a CAS is comprised of... agents or organizations, who resonate through sharing common interests, knowledge, and goals due to their history of interaction such as in the NRF

Minimal Representation and Decision Making for Networked Autonomous Agents

DTIC Science & Technology

2015-08-27

to a multi-vehicle version of the Travelling Salesman Problem (TSP). We further provided a direct formula for computing the number of robots...the sensor. As a first stab at this, the two-agent rendezvous problem is considered where one agent (the target) is equipped with no sensors and is...by the total distance traveled by all agents. For agents with limited sensing and communication capabilities, we give a formula that computes the

New agents for prostate cancer.

PubMed

Agarwal, N; Di Lorenzo, G; Sonpavde, G; Bellmunt, J

2014-09-01

The therapeutic landscape of metastatic castration-resistant prostate cancer (mCRPC) has been revolutionized by the arrival of multiple novel agents in the past 2 years. Immunotherapy in the form of sipuleucel-T, androgen axis inhibitors, including abiraterone acetate and enzalutamide, a chemotherapeutic agent, cabazitaxel, and a radiopharmaceutical, radium-223, have all yielded incremental extensions of survival and have been recently approved. A number of other agents appear promising in early studies, suggesting that the armamentarium against castrate-resistant prostate cancer is likely to continue to expand. Emerging androgen pathway inhibitors include androgen synthesis inhibitors (TAK700), androgen receptor inhibitors (ARN-509, ODM-201), AR DNA binding domain inhibitors (EPI-001), selective AR downregulators or SARDs (AZD-3514), and agents that inhibit both androgen synthesis and receptor binding (TOK-001/galeterone). Promising immunotherapeutic agents include poxvirus vaccines and CTLA-4 inhibitor (ipilimumab). Biologic agents targeting the molecular drivers of disease are also being investigated as single agents, including cabozantinib (Met and VEGFR2 inhibitor) and tasquinimod (angiogenesis and immune modulatory agent). Despite the disappointing results seen from studies evaluating docetaxel in combination with other agents, including GVAX, anti-angiogentic agents (bevacizumab, aflibercept, lenalinomide), a SRC kinase inhibitor (dasatinib), endothelin receptor antagonists (atrasentan, zibotentan), and high-dose calcitriol (DN-101), the results from the trial evaluating docetaxel in combination with the clusterin antagonist, custirsen, are eagerly awaited. New therapeutic hurdles consist of discovering new targets, understanding resistance mechanisms, the optimal sequencing and combinations of available agents, as well as biomarkers predictive for benefit. Novel agents targeting bone metastases are being developed following the success of zoledronic acid and denosumab. Finally, all of these modalities do not appear curative, suggesting that clinical trial enrollment and a better understanding of biology remain of paramount importance. © The Author 2014. Published by Oxford University Press on behalf of the European Society for Medical Oncology. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Biological agents with potential for misuse: a historical perspective and defensive measures.

PubMed

Bhalla, Deepak K; Warheit, David B

2004-08-15

Biological and chemical agents capable of producing serious illness or mortality have been used in biowarfare from ancient times. Use of these agents has progressed from crude forms in early and middle ages, when snakes and infected cadavers were used as weapons in battles, to sophisticated preparations for use during and after the second World War. Cults and terrorist organizations have attempted the use of biological agents with an aim to immobilize populations or cause serious harm. The reasons for interest in these agents by individuals and organizations include relative ease of acquisition, potential for causing mass casualty or panic, modest financing requirement, availability of technology, and relative ease of delivery. The Centers for Disease Control and Prevention has classified Critical Biological Agents into three major categories. This classification was based on several criteria, which include severity of impact on human health, potential for delivery in a weapon, capacity to cause panic and special needs for development, and stockpiling of medication. Agents that could cause the greatest harm following deliberate use were placed in category A. Category B included agents capable of producing serious harm and significant mortality but of lower magnitude than category A agents. Category C included emerging pathogens that could be developed for mass dispersion in future and their potential as a major health threat. A brief description of the category A bioagents is included and the pathophysiology of two particularly prominent agents, namely anthrax and smallpox, is discussed in detail. The potential danger from biological agents and their ever increasing threat to human populations have created a need for developing technologies for their early detection, for developing treatment strategies, and for refinement of procedures to ensure survival of affected individuals so as to attain the ultimate goal of eliminating the threat from intentional use of these agents. International treaties limiting development and proliferation of weapons and continuing development of defense strategies and safe guards against agents of concern are important elements of plans for eliminating this threat.

Multi-Agent Framework for Virtual Learning Spaces.

ERIC Educational Resources Information Center

Sheremetov, Leonid; Nunez, Gustavo

1999-01-01

Discussion of computer-supported collaborative learning, distributed artificial intelligence, and intelligent tutoring systems focuses on the concept of agents, and describes a virtual learning environment that has a multi-agent system. Describes a model of interactions in collaborative learning and discusses agents for Web-based virtual…

42 CFR 73.4 - Overlap select agents and toxins.

Code of Federal Regulations, 2014 CFR

2014-10-01

... Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES QUARANTINE, INSPECTION... its naturally occurring environment provided that the select agent or toxin has not been intentionally... such agent or toxin or destroys the agent or toxin by a recognized sterilization or inactivation...

20 CFR 655.133 - Requirements for agents.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 20 Employees' Benefits 3 2014-04-01 2014-04-01 false Requirements for agents. 655.133 Section 655.133 Employees' Benefits EMPLOYMENT AND TRAINING ADMINISTRATION, DEPARTMENT OF LABOR TEMPORARY... Procedures § 655.133 Requirements for agents. (a) An agent filing an Application for Temporary Employment...

14 CFR 29.1197 - Fire extinguishing agents.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Fire extinguishing agents. 29.1197 Section... AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Powerplant Powerplant Fire Protection § 29.1197 Fire extinguishing agents. (a) Fire extinguishing agents must— (1) Be capable of extinguishing flames emanating from...

A New Approach To Secure Federated Information Bases Using Agent Technology.

ERIC Educational Resources Information Center

Weippi, Edgar; Klug, Ludwig; Essmayr, Wolfgang

2003-01-01

Discusses database agents which can be used to establish federated information bases by integrating heterogeneous databases. Highlights include characteristics of federated information bases, including incompatible database management systems, schemata, and frequently changing context; software agent technology; Java agents; system architecture;…

Application and Implications of Agent Technology for Librarians.

ERIC Educational Resources Information Center

Nardi, Bonnie A.; O'Day, Vicki L.

1998-01-01

Examines intelligent software agents, presents nine design principles aimed specifically at the technology perspective (to personalize task performance and general principles), and discusses what librarians can do that software agents (agents defined as activity-aware software programs) cannot do. Describes an information ecology that integrates…

Mobile Agents Applications.

ERIC Educational Resources Information Center

Martins, Rosane Maria; Chaves, Magali Ribeiro; Pirmez, Luci; Rust da Costa Carmo, Luiz Fernando

2001-01-01

Discussion of the need to filter and retrieval relevant information from the Internet focuses on the use of mobile agents, specific software components which are based on distributed artificial intelligence and integrated systems. Surveys agent technology and discusses the agent building package used to develop two applications using IBM's Aglet…

Quantifying cancer cell receptors with paired-agent fluorescent imaging: a novel method to account for tissue optical property effects

NASA Astrophysics Data System (ADS)

Sadeghipour, Negar; Davis, Scott C.; Tichauer, Kenneth M.

2018-02-01

Dynamic fluorescence imaging approaches can be used to estimate the concentration of cell surface receptors in vivo. Kinetic models are used to generate the final estimation by taking the targeted imaging agent concentration as a function of time. However, tissue absorption and scattering properties cause the final readout signal to be on a different scale than the real fluorescent agent concentration. In paired-agent imaging approaches, simultaneous injection of a suitable control imaging agent with a targeted one can account for non-specific uptake and retention of the targeted agent. Additionally, the signal from the control agent can be a normalizing factor to correct for tissue optical property differences. In this study, the kinetic model used for paired-agent imaging analysis (i.e., simplified reference tissue model) is modified and tested in simulation and experimental data in a way that accounts for the scaling correction within the kinetic model fit to the data to ultimately extract an estimate of the targeted biomarker concentration.

Natural chelating agents for radionuclide decorporation

DOEpatents

Premuzic, E.T.

1985-06-11

This invention relates to the production of metal-binding compounds useful for the therapy of heavy metal poisoning, for biological mining and for decorporation of radionuclides. The present invention deals with an orderly and effective method of producing new therapeutically effective chelating agents. This method uses challenge biosynthesis for the production of chelating agents that are specific for a particular metal. In this approach, the desired chelating agents are prepared from microorganisms challenged by the metal that the chelating agent is designed to detoxify. This challenge induces the formation of specific or highly selective chelating agents. The present invention involves the use of the challenge biosynthetic method to produce new complexing/chelating agents that are therapeutically useful to detoxify uranium, plutonium, thorium and other toxic metals. The Pseudomonas aeruginosa family of organisms is the referred family of microorganisms to be used in the present invention to produce the new chelating agent because this family is known to elaborate strains resistant to toxic metals.

Military chemical warfare agent human subjects testing: part 2--long-term health effects among participants of U.S. military chemical warfare agent testing.

PubMed

Brown, Mark

2009-10-01

Military chemical warfare agent testing from World War I to 1975 produced thousands of veterans with concerns about how their participation affected their health. A companion article describes the history of these experiments, and how the lack of clinical data hampers evaluation of long-term health consequences. Conversely, much information is available about specific agents tested and their long-term health effects in other populations, which may be invaluable for helping clinicians respond effectively to the health care and other needs of affected veterans. The following review describes tested agents and their known long-term health consequences. Although hundreds of chemicals were tested, they fall into only about a half-dozen pharmaceutical classes, including common pharmaceuticals; anticholinesterase agents including military nerve agents and pesticides; anticholinergic glycolic acid esters such as atropine; acetylcholine reactivators such as 2-PAM; psychoactive compounds including cannabinoids, phencyclidine, and LSD; and irritants including tear gas and riot control agents.

Agent-Supported Mission Operations Teamwork

NASA Technical Reports Server (NTRS)

Malin, Jane T.

2003-01-01

This slide presentation reviews the development of software agents to support of mission operations teamwork. The goals of the work was to make automation by agents easy to use, supervise and direct, manage information and communication to decrease distraction, interruptions, workload and errors, reduce mission impact of off-nominal situations and increase morale and decrease turnover. The accomplishments or the project are: 1. Collaborative agents - mixed initiative and creation of instructions for mediating agent 2. Methods for prototyping, evaluating and evolving socio-technical systems 3. Technology infusion: teamwork tools in mISSIons 4. Demonstrations in simulation testbed An example of the use of agent is given, the use of an agent to monitor a N2 tank leak. An incomplete instruction to the agent is handled with mediating assistants, or Intelligent Briefing and Response Assistant (IBRA). The IBRA Engine also watches data stream for triggers and executes Act-Whenever actions. There is also a Briefing and Response Instruction (BRI) which is easy for a discipline specialist to create through a BRI editor.

Wealth distribution, Pareto law, and stretched exponential decay of money: Computer simulations analysis of agent-based models

NASA Astrophysics Data System (ADS)

Aydiner, Ekrem; Cherstvy, Andrey G.; Metzler, Ralf

2018-01-01

We study by Monte Carlo simulations a kinetic exchange trading model for both fixed and distributed saving propensities of the agents and rationalize the person and wealth distributions. We show that the newly introduced wealth distribution - that may be more amenable in certain situations - features a different power-law exponent, particularly for distributed saving propensities of the agents. For open agent-based systems, we analyze the person and wealth distributions and find that the presence of trap agents alters their amplitude, leaving however the scaling exponents nearly unaffected. For an open system, we show that the total wealth - for different trap agent densities and saving propensities of the agents - decreases in time according to the classical Kohlrausch-Williams-Watts stretched exponential law. Interestingly, this decay does not depend on the trap agent density, but rather on saving propensities. The system relaxation for fixed and distributed saving schemes are found to be different.

Nanodiamond-Manganese dual mode MRI contrast agents for enhanced liver tumor detection.

PubMed

Hou, Weixin; Toh, Tan Boon; Abdullah, Lissa Nurrul; Yvonne, Tay Wei Zheng; Lee, Kuan J; Guenther, Ilonka; Chow, Edward Kai-Hua

2017-04-01

Contrast agent-enhanced magnetic resonance (MR) imaging is critical for the diagnosis and monitoring of a number of diseases, including cancer. Certain clinical applications, including the detection of liver tumors, rely on both T1 and T2-weighted images even though contrast agent-enhanced MR imaging is not always reliable. Thus, there is a need for improved dual mode contrast agents with enhanced sensitivity. We report the development of a nanodiamond-manganese dual mode contrast agent that enhanced both T1 and T2-weighted MR imaging. Conjugation of manganese to nanodiamonds resulted in improved longitudinal and transverse relaxivity efficacy over unmodified MnCl 2 as well as clinical contrast agents. Following intravenous administration, nanodiamond-manganese complexes outperformed current clinical contrast agents in an orthotopic liver cancer mouse model while also reducing blood serum concentration of toxic free Mn 2+ ions. Thus, nanodiamond-manganese complexes may serve as more effective dual mode MRI contrast agent, particularly in cancer. Copyright © 2016 Elsevier Inc. All rights reserved.

Two decades of dendrimers as versatile MRI agents: a tale with and without metals.

PubMed

McMahon, Michael T; Bulte, Jeff W M

2018-05-01

Dendrimers or dendritic polymers are a class of compounds with great potential for nanomedical use. Some of their properties, including their rigidity, low polydispersity and the ease with which their surfaces can be modified make them particularly well suited for use as MRI diagnostic or theranostic agents. For the past 20 years, researchers have recognized this potential and refined dendrimer formulations to optimize these nanocarriers for a host of MRI applications, including blood pool imaging agents, lymph node imaging agents, tumor-targeted theranostic agents and cell tracking agents. This review summarizes the various types of dendrimers according to the type of MR contrast they can provide. This includes the metallic T 1 , T 2 and paraCEST imaging agents, and the non-metallic diaCEST and fluorinated ( 19 F) heteronuclear imaging agents. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Implantable Materials and Surgical Technologies > Nanomaterials and Implants. © 2017 Wiley Periodicals, Inc.

Current and Developing Technologies for Monitoring Agents of Bioterrorism and Biowarfare

PubMed Central

Lim, Daniel V.; Simpson, Joyce M.; Kearns, Elizabeth A.; Kramer, Marianne F.

2005-01-01

Recent events have made public health officials acutely aware of the importance of rapidly and accurately detecting acts of bioterrorism. Because bioterrorism is difficult to predict or prevent, reliable platforms to rapidly detect and identify biothreat agents are important to minimize the spread of these agents and to protect the public health. These platforms must not only be sensitive and specific, but must also be able to accurately detect a variety of pathogens, including modified or previously uncharacterized agents, directly from complex sample matrices. Various commercial tests utilizing biochemical, immunological, nucleic acid, and bioluminescence procedures are currently available to identify biological threat agents. Newer tests have also been developed to identify such agents using aptamers, biochips, evanescent wave biosensors, cantilevers, living cells, and other innovative technologies. This review describes these current and developing technologies and considers challenges to rapid, accurate detection of biothreat agents. Although there is no ideal platform, many of these technologies have proved invaluable for the detection and identification of biothreat agents. PMID:16223949

Protection of Mobile Agents Execution Using a Modified Self-Validating Branch-Based Software Watermarking with External Sentinel

NASA Astrophysics Data System (ADS)

Tomàs-Buliart, Joan; Fernández, Marcel; Soriano, Miguel

Critical infrastructures are usually controlled by software entities. To monitor the well-function of these entities, a solution based in the use of mobile agents is proposed. Some proposals to detect modifications of mobile agents, as digital signature of code, exist but they are oriented to protect software against modification or to verify that an agent have been executed correctly. The aim of our proposal is to guarantee that the software is being executed correctly by a non trusted host. The way proposed to achieve this objective is by the improvement of the Self-Validating Branch-Based Software Watermarking by Myles et al.. The proposed modification is the incorporation of an external element called sentinel which controls branch targets. This technique applied in mobile agents can guarantee the correct operation of an agent or, at least, can detect suspicious behaviours of a malicious host during the execution of the agent instead of detecting when the execution of the agent have finished.

Scoping Planning Agents With Shared Models

NASA Technical Reports Server (NTRS)

Bedrax-Weiss, Tania; Frank, Jeremy D.; Jonsson, Ari K.; McGann, Conor

2003-01-01

In this paper we provide a formal framework to define the scope of planning agents based on a single declarative model. Having multiple agents sharing a single model provides numerous advantages that lead to reduced development costs and increase reliability of the system. We formally define planning in terms of extensions of an initial partial plan, and a set of flaws that make the plan unacceptable. A Flaw Filter (FF) allows us to identify those flaws relevant to an agent. Flaw filters motivate the Plan Identification Function (PIF), which specifies when an agent is is ready hand control to another agent for further work. PIFs define a set of plan extensions that can be generated from a model and a plan request. FFs and PIFs can be used to define the scope of agents without changing the model. We describe an implementation of PIFsand FFswithin the context of EUROPA, a constraint-based planning architecture, and show how it can be used to easily design many different agents.

A CSP-Based Agent Modeling Framework for the Cougaar Agent-Based Architecture

NASA Technical Reports Server (NTRS)

Gracanin, Denis; Singh, H. Lally; Eltoweissy, Mohamed; Hinchey, Michael G.; Bohner, Shawn A.

2005-01-01

Cognitive Agent Architecture (Cougaar) is a Java-based architecture for large-scale distributed agent-based applications. A Cougaar agent is an autonomous software entity with behaviors that represent a real-world entity (e.g., a business process). A Cougaar-based Model Driven Architecture approach, currently under development, uses a description of system's functionality (requirements) to automatically implement the system in Cougaar. The Communicating Sequential Processes (CSP) formalism is used for the formal validation of the generated system. Two main agent components, a blackboard and a plugin, are modeled as CSP processes. A set of channels represents communications between the blackboard and individual plugins. The blackboard is represented as a CSP process that communicates with every agent in the collection. The developed CSP-based Cougaar modeling framework provides a starting point for a more complete formal verification of the automatically generated Cougaar code. Currently it is used to verify the behavior of an individual agent in terms of CSP properties and to analyze the corresponding Cougaar society.

Fibrous Filter to Protect Building Environments from Polluting Agents: A Review

NASA Astrophysics Data System (ADS)

Chavhan, Md. Vaseem; Mukhopadhyay, Arunangshu

2016-04-01

This paper discusses the use of fibrous filter to protect the building environments from air born polluting agents and especially of concern chemical, biological and radiological agents. Air-filtration includes removal of particulate from air and toxic gases from air. In air filtration, particulate which are mostly biological and radioactive types of agents can be removed by using mechanical and electrostatic filters. Some biological agents, which cannot be removed by air filtration alone, special techniques like antimicrobial finish, UV germicides, coated filters etc. are required. Biocide agent can be added into the fibre itself by grafting reaction to impart antimicrobial activity. Chemical agents like toxic gases can be removed by integrating adsorbents and sorbents in filters or by fibre modifications. It is also possible to impart catalytic conversion properties into the fibre to remove volatile gasous. Radioactive agents can be removed by particulate filter if present in the form of aerosol or by gas cleaning by the use of specific fibre impregnate.

Agent-based models of cellular systems.

PubMed

Cannata, Nicola; Corradini, Flavio; Merelli, Emanuela; Tesei, Luca

2013-01-01

Software agents are particularly suitable for engineering models and simulations of cellular systems. In a very natural and intuitive manner, individual software components are therein delegated to reproduce "in silico" the behavior of individual components of alive systems at a given level of resolution. Individuals' actions and interactions among individuals allow complex collective behavior to emerge. In this chapter we first introduce the readers to software agents and multi-agent systems, reviewing the evolution of agent-based modeling of biomolecular systems in the last decade. We then describe the main tools, platforms, and methodologies available for programming societies of agents, possibly profiting also of toolkits that do not require advanced programming skills.

Method, apparatus and system for managing queue operations of a test bench environment

DOEpatents

Ostler, Farrell Lynn

2016-07-19

Techniques and mechanisms for performing dequeue operations for agents of a test bench environment. In an embodiment, a first group of agents are each allocated a respective ripe reservation and a second set of agents are each allocated a respective unripe reservation. Over time, queue management logic allocates respective reservations to agents and variously changes one or more such reservations from unripe to ripe. In another embodiment, an order of servicing agents allocated unripe reservations is based on relative priorities of the unripe reservations with respect to one another. An order of servicing agents allocated ripe reservations is on a first come, first served basis.

Method for photo-altering a biological system to improve biological effect

DOEpatents

Hill, Richard A.; Doiron, Daniel R.; Crean, David H.

2000-08-01

Photodynamic therapy is a new adjunctive therapy for filtration surgery that does not use chemotherapy agents or radiation, but uses pharmacologically-active sensitizing compounds to produce a titratable, localized, transient, post operative avascular conjunctiva. A photosensitizing agent in a biological system is selectively activated by delivering the photosensitive agent to the biological system and laser activating only a spatially selected portion of the delivered photosensitive agent. The activated portion of the photosensitive agent reacts with the biological system to obtain a predetermined biological effect. As a result, an improved spatial disposition and effectuation of the biological effect by the photosensitive agent in the biological system is achieved.

Exact solution of a modified El Farol's bar problem: Efficiency and the role of market impact

NASA Astrophysics Data System (ADS)

Marsili, Matteo; Challet, Damien; Zecchina, Riccardo

2000-06-01

We discuss a model of heterogeneous, inductive rational agents inspired by the El Farol Bar problem and the Minority Game. As in markets, agents interact through a collective aggregate variable - which plays a role similar to price - whose value is fixed by all of them. Agents follow a simple reinforcement-learning dynamics where the reinforcement, for each of their available strategies, is related to the payoff delivered by that strategy. We derive the exact solution of the model in the “thermodynamic” limit of infinitely many agents using tools of statistical physics of disordered systems. Our results show that the impact of agents on the market price plays a key role: even though price has a weak dependence on the behavior of each individual agent, the collective behavior crucially depends on whether agents account for such dependence or not. Remarkably, if the adaptive behavior of agents accounts even “infinitesimally” for this dependence they can, in a whole range of parameters, reduce global fluctuations by a finite amount. Both global efficiency and individual utility improve with respect to a “price taker” behavior if agents account for their market impact.

Intelligent Design of Nano-Scale Molecular Imaging Agents

PubMed Central

Kim, Sung Bae; Hattori, Mitsuru; Ozawa, Takeaki

2012-01-01

Visual representation and quantification of biological processes at the cellular and subcellular levels within living subjects are gaining great interest in life science to address frontier issues in pathology and physiology. As intact living subjects do not emit any optical signature, visual representation usually exploits nano-scale imaging agents as the source of image contrast. Many imaging agents have been developed for this purpose, some of which exert nonspecific, passive, and physical interaction with a target. Current research interest in molecular imaging has mainly shifted to fabrication of smartly integrated, specific, and versatile agents that emit fluorescence or luminescence as an optical readout. These agents include luminescent quantum dots (QDs), biofunctional antibodies, and multifunctional nanoparticles. Furthermore, genetically encoded nano-imaging agents embedding fluorescent proteins or luciferases are now gaining popularity. These agents are generated by integrative design of the components, such as luciferase, flexible linker, and receptor to exert a specific on–off switching in the complex context of living subjects. In the present review, we provide an overview of the basic concepts, smart design, and practical contribution of recent nano-scale imaging agents, especially with respect to genetically encoded imaging agents. PMID:23235326

Rigorous Proof of the Boltzmann-Gibbs Distribution of Money on Connected Graphs

NASA Astrophysics Data System (ADS)

Lanchier, Nicolas

2017-04-01

Models in econophysics, i.e., the emerging field of statistical physics that applies the main concepts of traditional physics to economics, typically consist of large systems of economic agents who are characterized by the amount of money they have. In the simplest model, at each time step, one agent gives one dollar to another agent, with both agents being chosen independently and uniformly at random from the system. Numerical simulations of this model suggest that, at least when the number of agents and the average amount of money per agent are large, the distribution of money converges to an exponential distribution reminiscent of the Boltzmann-Gibbs distribution of energy in physics. The main objective of this paper is to give a rigorous proof of this result and show that the convergence to the exponential distribution holds more generally when the economic agents are located on the vertices of a connected graph and interact locally with their neighbors rather than globally with all the other agents. We also study a closely related model where, at each time step, agents buy with a probability proportional to the amount of money they have, and prove that in this case the limiting distribution of money is Poissonian.

Intelligent design of nano-scale molecular imaging agents.

PubMed

Kim, Sung Bae; Hattori, Mitsuru; Ozawa, Takeaki

2012-12-12

Visual representation and quantification of biological processes at the cellular and subcellular levels within living subjects are gaining great interest in life science to address frontier issues in pathology and physiology. As intact living subjects do not emit any optical signature, visual representation usually exploits nano-scale imaging agents as the source of image contrast. Many imaging agents have been developed for this purpose, some of which exert nonspecific, passive, and physical interaction with a target. Current research interest in molecular imaging has mainly shifted to fabrication of smartly integrated, specific, and versatile agents that emit fluorescence or luminescence as an optical readout. These agents include luminescent quantum dots (QDs), biofunctional antibodies, and multifunctional nanoparticles. Furthermore, genetically encoded nano-imaging agents embedding fluorescent proteins or luciferases are now gaining popularity. These agents are generated by integrative design of the components, such as luciferase, flexible linker, and receptor to exert a specific on-off switching in the complex context of living subjects. In the present review, we provide an overview of the basic concepts, smart design, and practical contribution of recent nano-scale imaging agents, especially with respect to genetically encoded imaging agents.

Uncertainty in a spatial evacuation model

NASA Astrophysics Data System (ADS)

Mohd Ibrahim, Azhar; Venkat, Ibrahim; Wilde, Philippe De

2017-08-01

Pedestrian movements in crowd motion can be perceived in terms of agents who basically exhibit patient or impatient behavior. We model crowd motion subject to exit congestion under uncertainty conditions in a continuous space and compare the proposed model via simulations with the classical social force model. During a typical emergency evacuation scenario, agents might not be able to perceive with certainty the strategies of opponents (other agents) owing to the dynamic changes entailed by the neighborhood of opponents. In such uncertain scenarios, agents will try to update their strategy based on their own rules or their intrinsic behavior. We study risk seeking, risk averse and risk neutral behaviors of such agents via certain game theory notions. We found that risk averse agents tend to achieve faster evacuation time whenever the time delay in conflicts appears to be longer. The results of our simulations also comply with previous work and conform to the fact that evacuation time of agents becomes shorter once mutual cooperation among agents is achieved. Although the impatient strategy appears to be the rational strategy that might lead to faster evacuation times, our study scientifically shows that the more the agents are impatient, the slower is the egress time.

Mobile code security

NASA Astrophysics Data System (ADS)

Ramalingam, Srikumar

2001-11-01

A highly secure mobile agent system is very important for a mobile computing environment. The security issues in mobile agent system comprise protecting mobile hosts from malicious agents, protecting agents from other malicious agents, protecting hosts from other malicious hosts and protecting agents from malicious hosts. Using traditional security mechanisms the first three security problems can be solved. Apart from using trusted hardware, very few approaches exist to protect mobile code from malicious hosts. Some of the approaches to solve this problem are the use of trusted computing, computing with encrypted function, steganography, cryptographic traces, Seal Calculas, etc. This paper focuses on the simulation of some of these existing techniques in the designed mobile language. Some new approaches to solve malicious network problem and agent tampering problem are developed using public key encryption system and steganographic concepts. The approaches are based on encrypting and hiding the partial solutions of the mobile agents. The partial results are stored and the address of the storage is destroyed as the agent moves from one host to another host. This allows only the originator to make use of the partial results. Through these approaches some of the existing problems are solved.

Blood-pool contrast agent for pre-clinical computed tomography

NASA Astrophysics Data System (ADS)

Cruje, Charmainne; Tse, Justin J.; Holdsworth, David W.; Gillies, Elizabeth R.; Drangova, Maria

2017-03-01

Advances in nanotechnology have led to the development of blood-pool contrast agents for micro-computed tomography (micro-CT). Although long-circulating nanoparticle-based agents exist for micro-CT, they are predominantly based on iodine, which has a low atomic number. Micro-CT contrast increases when using elements with higher atomic numbers (i.e. lanthanides), particularly at higher energies. The purpose of our work was to develop and evaluate a lanthanide-based blood-pool contrast agent that is suitable for in vivo micro-CT. We synthesized a contrast agent in the form of polymer-encapsulated Gd nanoparticles and evaluated its stability in vitro. The synthesized nanoparticles were shown to have an average diameter of 127 +/- 6 nm, with good size dispersity. Particle size distribution - evaluated by dynamic light scattering over the period of two days - demonstrated no change in size of the contrast agent in water and saline. Additionally, our contrast agent was stable in a mouse serum mimic for up to 30 minutes. CT images of the synthesized contrast agent (containing 27 mg/mL of Gd) demonstrated an attenuation of over 1000 Hounsfield Units. This approach to synthesizing a Gd-based blood-pool contrast agent promises to enhance the capabilities of micro-CT imaging.

Agent Collaborative Target Localization and Classification in Wireless Sensor Networks

PubMed Central

Wang, Xue; Bi, Dao-wei; Ding, Liang; Wang, Sheng

2007-01-01

Wireless sensor networks (WSNs) are autonomous networks that have been frequently deployed to collaboratively perform target localization and classification tasks. Their autonomous and collaborative features resemble the characteristics of agents. Such similarities inspire the development of heterogeneous agent architecture for WSN in this paper. The proposed agent architecture views WSN as multi-agent systems and mobile agents are employed to reduce in-network communication. According to the architecture, an energy based acoustic localization algorithm is proposed. In localization, estimate of target location is obtained by steepest descent search. The search algorithm adapts to measurement environments by dynamically adjusting its termination condition. With the agent architecture, target classification is accomplished by distributed support vector machine (SVM). Mobile agents are employed for feature extraction and distributed SVM learning to reduce communication load. Desirable learning performance is guaranteed by combining support vectors and convex hull vectors. Fusion algorithms are designed to merge SVM classification decisions made from various modalities. Real world experiments with MICAz sensor nodes are conducted for vehicle localization and classification. Experimental results show the proposed agent architecture remarkably facilitates WSN designs and algorithm implementation. The localization and classification algorithms also prove to be accurate and energy efficient.

The effect of interstitial pressure on therapeutic agent transport: coupling with the tumor blood and lymphatic vascular systems.

PubMed

Wu, Min; Frieboes, Hermann B; Chaplain, Mark A J; McDougall, Steven R; Cristini, Vittorio; Lowengrub, John S

2014-08-21

Vascularized tumor growth is characterized by both abnormal interstitial fluid flow and the associated interstitial fluid pressure (IFP). Here, we study the effect that these conditions have on the transport of therapeutic agents during chemotherapy. We apply our recently developed vascular tumor growth model which couples a continuous growth component with a discrete angiogenesis model to show that hypertensive IFP is a physical barrier that may hinder vascular extravasation of agents through transvascular fluid flux convection, which drives the agents away from the tumor. This result is consistent with previous work using simpler models without blood flow or lymphatic drainage. We consider the vascular/interstitial/lymphatic fluid dynamics to show that tumors with larger lymphatic resistance increase the agent concentration more rapidly while also experiencing faster washout. In contrast, tumors with smaller lymphatic resistance accumulate less agents but are able to retain them for a longer time. The agent availability (area-under-the curve, or AUC) increases for less permeable agents as lymphatic resistance increases, and correspondingly decreases for more permeable agents. We also investigate the effect of vascular pathologies on agent transport. We show that elevated vascular hydraulic conductivity contributes to the highest AUC when the agent is less permeable, but to lower AUC when the agent is more permeable. We find that elevated interstitial hydraulic conductivity contributes to low AUC in general regardless of the transvascular agent transport capability. We also couple the agent transport with the tumor dynamics to simulate chemotherapy with the same vascularized tumor under different vascular pathologies. We show that tumors with an elevated interstitial hydraulic conductivity alone require the strongest dosage to shrink. We further show that tumors with elevated vascular hydraulic conductivity are more hypoxic during therapy and that the response slows down as the tumor shrinks due to the heterogeneity and low concentration of agents in the tumor interior compared with the cases where other pathological effects may combine to flatten the IFP and thus reduce the heterogeneity. We conclude that dual normalizations of the micronevironment - both the vasculature and the interstitium - are needed to maximize the effects of chemotherapy, while normalization of only one of these may be insufficient to overcome the physical resistance and may thus lead to sub-optimal outcomes. Copyright © 2014 Elsevier Ltd. All rights reserved.

The effect of interstitial pressure on therapeutic agent transport: coupling with the tumor blood and lymphatic vascular systems

PubMed Central

Wu, Min; Frieboes, Hermann B.; Chaplain, Mark A.J.; McDougall, Steven R.; Cristini, Vittorio; Lowengrub, John

2014-01-01

Vascularized tumor growth is characterized by both abnormal interstitial fluid flow and the associated interstitial fluid pressure (IFP). Here, we study the effect that these conditions have on the transport of therapeutic agents during chemotherapy. We apply our recently developed vascular tumor growth model which couples a continuous growth component with a discrete angiogenesis model to show that hypertensive IFP is a physical barrier that may hinder vascular extravasation of agents through transvascular fluid flux convection, which drives the agents away from the tumor. This result is consistent with previous work using simpler models without blood flow or lymphatic drainage. We consider the vascular/interstitial/lymphatic fluid dynamics to show that tumors with larger lymphatic resistance increase the agent concentration more rapidly while also experiencing faster washout. In contrast, tumors with smaller lymphatic resistance accumulate less agents but are able to retain them for a longer time. The agent availability (area-under-the curve, or AUC) increases for less permeable agents as lymphatic resistance increases, and correspondingly decreases for more permeable agents. We also investigate the effect of vascular pathologies on agent transport. We show that elevated vascular hydraulic conductivity contributes to the highest AUC when the agent is less permeable, but leads to lower AUC when the agent is more permeable. We find that elevated interstitial hydraulic conductivity contributes to low AUC in general regardless of the transvascular agent transport capability. We also couple the agent transport with the tumor dynamics to simulate chemotherapy with the same vascularized tumor under different vascular pathologies. We show that tumors with an elevated interstitial hydraulic conductivity alone require the strongest dosage to shrink. We further show that tumors with elevated vascular hydraulic conductivity are more hypoxic during therapy and that the response slows down as the tumor shrinks due to the heterogeneity and low concentration of agents in the tumor interior compared with the cases where other pathological effects may combine to flatten the IFP and thus reduce the heterogeneity. We conclude that dual normalizations of the micronevironment - both the vasculature and the interstitium - are needed to maximize the effects of chemotherapy, while normalization of only one of these may be insufficient to overcome the physical resistance and thus leads to sub-optimal outcomes. PMID:24751927

Ferrimagnetic susceptibility contrast agents.

PubMed

Bach-Gansmo, T

1993-01-01

Contrast agents based on superparamagnetic particles have been in clinical development for more than 5 years, and the complexity of their effects is still not elucidated. The relaxivities are frequently used to give an idea of their efficacy, but these parameters can only be used if they are concentration independent. For large superparamagnetic systems, the evolution of the transverse magnetization is biexponential, after an initial loss of magnetization. Both these characteristics of large superparamagnetic systems should lead to prudence in using the relaxivities as indicators of contrast medium efficacy. Susceptibility induced artefacts have been associated with the use of superparamagnetic contrast agents since the first imaging evaluation took place. The range of concentrations where good contrast effect was achieved without inducing artefacts, as well as blurring and metal artefacts were evaluated. The influence of motion on the induction of artefacts was studied, and compared to the artefacts induced by a paramagnetic agent subject to motion. With a suitable concentration of a negative contrast agent, a signal void could be achieved in the region prone to motion, and no artefacts were induced. If the concentration was too high, a displacement of the region close to the contrast agent was observed. The artefacts occurred in a volume surrounding the contrast agent, i.e., also outside the imaging plane. In comparison a positive, paramagnetic contrast agent induced heavy artefacts in the phase encoding direction, appearing as both high intensity regions and black holes, in a mosaic pattern. Clinical trials of the oral contrast agent OMP for abdominal MR imaging showed this agent to be safe and efficacious. OMP increased the diagnostic efficacy of abdominal MR imaging in 2 of 3 cases examined, with a significant decrease in motion artefacts. Susceptibility contrast agents may also be of use in the evaluation of small lesions in the liver. Particulate material injected i.v. will be targeted to the liver and spleen by way of the mononuclear phagocyte system (MPS). Small particles, without specific receptor affinities were targeted to the hepatocytes and the MPS. The distribution correlated with a high efficiency as a contrast agent, whereas no correlation to in vitro relaxation rates and relaxivities could be found. Superparamagnetic particles have important possibilities as contrast agents. The identification of in vitro properties of these agents may help the comparison of various agents before in vivo imaging.

42 CFR 73.4 - Overlap select agents and toxins.

Code of Federal Regulations, 2013 CFR

2013-10-01

... Public Health PUBLIC HEALTH SERVICE, DEPARTMENT OF HEALTH AND HUMAN SERVICES QUARANTINE, INSPECTION... its naturally occurring environment provided that the select agent or toxin has not been intentionally... an entity eligible to receive such agent or toxin or destroys the agent or toxin by a recognized...

Online Deception Detection Using BDI Agents

ERIC Educational Resources Information Center

Merritts, Richard A.

2013-01-01

This research has two facets within separate research areas. The research area of Belief, Desire and Intention (BDI) agent capability development was extended. Deception detection research has been advanced with the development of automation using BDI agents. BDI agents performed tasks automatically and autonomously. This study used these…

Roles of Change Agents in Development. Occasional Paper #3.

ERIC Educational Resources Information Center

O'Gorman, Frances

The roles of change agents in community development are manifest (surface actions of agents interacting with clients) and latent (derived from undercurrents that give directions to the agents' actions). Manifest roles are as starter (facilitator, analyzer, leadership developer); go-between (informer, linker); and accomplisher (organizer,…

Designing Distributed Learning Environments with Intelligent Software Agents

ERIC Educational Resources Information Center

Lin, Fuhua, Ed.

2005-01-01

"Designing Distributed Learning Environments with Intelligent Software Agents" reports on the most recent advances in agent technologies for distributed learning. Chapters are devoted to the various aspects of intelligent software agents in distributed learning, including the methodological and technical issues on where and how intelligent agents…

14 CFR 29.1199 - Extinguishing agent containers.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Extinguishing agent containers. 29.1199....1199 Extinguishing agent containers. (a) Each extinguishing agent container must have a pressure relief to prevent bursting of the container by excessive internal pressures. (b) The discharge end of each...

Neuromuscular Blockade and Reversal Agents: A Primer for Postanesthesia Nurses.

ERIC Educational Resources Information Center

Pesci, Barbara R.

1986-01-01

Presents a comprehensive review of neuromuscular blocking agents, reversal agents used in anesthesia, and factors affecting reversal. It is aimed at nurses who provide care to patients recovering from anesthesia. It discusses the neuromuscular transmission system, depolarizing muscle relaxants, nondepolarizing blocking agents, and criteria for…

13 CFR 120.951 - Selling agent.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 13 Business Credit and Assistance 1 2013-01-01 2013-01-01 false Selling agent. 120.951 Section 120.951 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION BUSINESS LOANS Development Company Loan Program (504) Debenture Sales and Service Agents § 120.951 Selling agent. The CDC, with SBA...

13 CFR 120.951 - Selling agent.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 13 Business Credit and Assistance 1 2011-01-01 2011-01-01 false Selling agent. 120.951 Section 120.951 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION BUSINESS LOANS Development Company Loan Program (504) Debenture Sales and Service Agents § 120.951 Selling agent. The CDC, with SBA...

13 CFR 120.951 - Selling agent.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Selling agent. 120.951 Section 120.951 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION BUSINESS LOANS Development Company Loan Program (504) Debenture Sales and Service Agents § 120.951 Selling agent. The CDC, with SBA...

13 CFR 120.951 - Selling agent.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 13 Business Credit and Assistance 1 2014-01-01 2014-01-01 false Selling agent. 120.951 Section 120.951 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION BUSINESS LOANS Development Company Loan Program (504) Debenture Sales and Service Agents § 120.951 Selling agent. The CDC, with SBA...

13 CFR 120.951 - Selling agent.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 13 Business Credit and Assistance 1 2012-01-01 2012-01-01 false Selling agent. 120.951 Section 120.951 Business Credit and Assistance SMALL BUSINESS ADMINISTRATION BUSINESS LOANS Development Company Loan Program (504) Debenture Sales and Service Agents § 120.951 Selling agent. The CDC, with SBA...

Development of agent-based on-line adaptive signal control (ASC) framework using connected vehicle (CV) technology.

DOT National Transportation Integrated Search

2016-04-01

In this study, we developed an adaptive signal control (ASC) framework for connected vehicles (CVs) using agent-based modeling technique. : The proposed framework consists of two types of agents: 1) vehicle agents (VAs); and 2) signal controller agen...

Capping agents in nanoparticle synthesis: Surfactant and solvent system

NASA Astrophysics Data System (ADS)

Gulati, Shivani; Sachdeva, M.; Bhasin, K. K.

2018-05-01

The preparation of nanomaterials by organometallic precursors require a capping agent, which primarily acts as stabilizing agent and provide colloidal stability along with preventing agglomeration and stopping uncontrolled growth. Final morphology of nanocrystal largely depends on the type of capping agent which is adsorbed on the surface of nanocrystal. Thus capping agents are the keys to obtain the small-sized nanoparticles and are very frequently used in colloidal synthesis of nanoparticles to avoid its overgrowth.

Conversational Agents in E-Learning

NASA Astrophysics Data System (ADS)

Kerry, Alice; Ellis, Richard; Bull, Susan

This paper discusses the use of natural language or 'conversational' agents in e-learning environments. We describe and contrast the various applications of conversational agent technology represented in the e-learning literature, including tutors, learning companions, language practice and systems to encourage reflection. We offer two more detailed examples of conversational agents, one which provides learning support, and the other support for self-assessment. Issues and challenges for developers of conversational agent systems for e-learning are identified and discussed.

Extinguishing agent for combustible metal fires

DOEpatents

Riley, John F.; Stauffer, Edgar Eugene

1976-10-12

A low chloride extinguishing agent for combustible metal fires comprising from substantially 75 to substantially 94 weight percent of sodium carbonate as the basic fire extinguishing material, from substantially 1 to substantially 5 weight percent of a water-repellent agent such as a metal stearate, from substantially 2 to substantially 10 weight percent of a flow promoting agent such as attapulgus clay, and from substantially 3 to substantially 15 weight percent of a polyamide resin as a crusting agent.

Adenovirus-Mediated Gene Therapy Against Viral Biothreat Agents

DTIC Science & Technology

2016-04-12

economy. Vaccine development is an important strategy to thwart the threat of these viral biothreat agents. There is an urgent need to improve...Alberta, Tl A 8K6. Canada E-mail: josh. wu@drdc-rddc.gc.ca .• 78 JoshQ.H. Wu existing vaccines against these agents and to develop new ones. Gene...of vaccines against viral biothreat agents. Genes encoding protective antigens of viral biothreat agents can be carried by these viral vectors and

TANDEM: A Trust-Based Agent Framework for Networked Decision Making

DTIC Science & Technology

2015-09-10

selective (20–80 %), while the rest are good citizens, trust acts as a method to isolate misbehaving agents. If the majority of the agents have high...competence and low selectivity, then they can use trust to isolate route information around the misbehaving agents, improving Comm and Steps. The impact is...more dramatic when only 20–40 % of the agents are misbehaving . However, using trust results in reduced SA as the information available at the

Seldon v.3.0

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berry, Nina; Ko, Teresa; Shneider, Max

Seldon is an agent-based social simulation framework that uniquely integrates concepts from a variety of different research areas including psychology, social science, and agent-based modeling. Development has been taking place for a number of years, previously focusing on gang and terrorist recruitment. The toolkit consists of simple agents (individuals) and abstract agents (groups of individuals representing social/institutional concepts) that interact according to exchangeable rule sets (i.e. linear attraction, linear reinforcement). Each agent has a set of customizable attributes that get modified during the interactions. Interactions create relationships between agents, and each agent has a maximum amount of relationship energy thatmore » it can expend. As relationships evolve, they form multiple levels of social networks (i.e. acquaintances, friends, cliques) that in turn drive future interactions. Agents can also interact randomly if they are not connected through a network, mimicking the chance interactions that real people have in everyday life. We are currently integrating Seldon with the cognitive framework (also developed at Sandia). Each individual agent has a lightweight cognitive model that is created automatically from textual sources. Cognitive information is exchanged during interactions, and can also be injected into a running simulation. The entire framework has been parallelized to allow for larger simulations in an HPC environment. We have also added more detail to the agents themselves (a"Big Five" personality model) and their interactions (an enhanced relationship model) for a more realistic representation.« less

Isobolographic Analysis of Pharmacodynamic Interactions between Antifungal Agents and Ciprofloxacin against Candida albicans and Aspergillus fumigatus▿

PubMed Central

Stergiopoulou, Theodouli; Meletiadis, Joseph; Sein, Tin; Papaioannidou, Paraskevi; Tsiouris, Ioannis; Roilides, Emmanuel; Walsh, Thomas J.

2008-01-01

Patients suffering from invasive mycoses often receive concomitant antifungal therapy and antibacterial agents. Assessment of pharmacodynamic interactions between antifungal and antibacterial agents is complicated by the absence of a common antifungal end point for both agents. Ciprofloxacin has no intrinsic antifungal activity but may interact with antifungal agents, since it inhibits DNA gyrase (topoisomerase II), which is abundant in fungi. We therefore employed isobolographic analysis adapted to incorporate a nonactive agent in order to analyze the potential in vitro interaction between the fluoroquinolone ciprofloxacin and several representative antifungal agents against Candida albicans and Aspergillus fumigatus strains by using a microdilution checkerboard technique. In agreement with earlier in vitro studies, conventional fractional inhibitory concentration index analysis was unable to detect interactions between ciprofloxacin and antifungal agents. However, isobolographic analysis revealed significant pharmacodynamic interactions between antifungal agents and ciprofloxacin against C. albicans and A. fumigatus strains. Amphotericin B demonstrated concentration-dependent interactions for both species, with synergy (interaction indices, 0.14 to 0.81) observed at ciprofloxacin concentrations of <10.64 μg/ml. Synergy (interaction indices, 0.10 to 0.86) was also found for voriconazole and caspofungin against A. fumigatus. Isobolographic analysis may help to elucidate the pharmacodynamic interactions between antifungal and non-antifungal agents and to develop better management strategies against invasive candidiasis and aspergillosis. PMID:18299413

Combining Human and Machine Intelligence to Derive Agents' Behavioral Rules for Groundwater Irrigation

NASA Astrophysics Data System (ADS)

Hu, Y.; Quinn, C.; Cai, X.

2015-12-01

One major challenge of agent-based modeling is to derive agents' behavioral rules due to behavioral uncertainty and data scarcity. This study proposes a new approach to combine a data-driven modeling based on the directed information (i.e., machine intelligence) with expert domain knowledge (i.e., human intelligence) to derive the behavioral rules of agents considering behavioral uncertainty. A directed information graph algorithm is applied to identifying the causal relationships between agents' decisions (i.e., groundwater irrigation depth) and time-series of environmental, socio-economical and institutional factors. A case study is conducted for the High Plains aquifer hydrological observatory (HO) area, U.S. Preliminary results show that four factors, corn price (CP), underlying groundwater level (GWL), monthly mean temperature (T) and precipitation (P) have causal influences on agents' decisions on groundwater irrigation depth (GWID) to various extents. Based on the similarity of the directed information graph for each agent, five clusters of graphs are further identified to represent all the agents' behaviors in the study area as shown in Figure 1. Using these five representative graphs, agents' monthly optimal groundwater pumping rates are derived through the probabilistic inference. Such data-driven relationships and probabilistic quantifications are then coupled with a physically-based groundwater model to investigate the interactions between agents' pumping behaviors and the underlying groundwater system in the context of coupled human and natural systems.

Representation in dynamical agents.

PubMed

Ward, Ronnie; Ward, Robert

2009-04-01

This paper extends experiments by Beer [Beer, R. D. (1996). Toward the evolution of dynamical neural networks for minimally cognitive behavior. In P. Maes, M. Mataric, J. Meyer, J. Pollack, & S. Wilson (Eds.), From animals to animats 4: Proceedings of the fourth international conference on simulation of adaptive behavior (pp. 421-429). MIT Press; Beer, R. D. (2003). The dynamics of active categorical perception in an evolved model agent (with commentary and response). Adaptive Behavior, 11 (4), 209-243] with an evolved, dynamical agent to further explore the question of representation in cognitive systems. Beer's environmentally-situated visual agent was controlled by a continuous-time recurrent neural network, and evolved to perform a categorical perception task, discriminating circles from diamonds. Despite the agent's high levels of discrimination performance, Beer found no evidence of internal representation in the best-evolved agent's nervous system. Here we examine the generality of this result. We evolved an agent for shape discrimination, and performed extensive behavioral analyses to test for representation. In this case we find that agents developed to discriminate equal-width shapes exhibit what Clark [Clark, A. (1997). The dynamical challenge. Cognitive Science, 21 (4), 461-481] calls "weak-substantive representation". The agent had internal configurations that (1) were understandably related to the object in the environment, and (2) were functionally used in a task relevant way when the target was not visible to the agent.

Tracking dynamic team activity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tambe, M.

1996-12-31

AI researchers are striving to build complex multi-agent worlds with intended applications ranging from the RoboCup robotic soccer tournaments, to interactive virtual theatre, to large-scale real-world battlefield simulations. Agent tracking - monitoring other agent`s actions and inferring their higher-level goals and intentions - is a central requirement in such worlds. While previous work has mostly focused on tracking individual agents, this paper goes beyond by focusing on agent teams. Team tracking poses the challenge of tracking a team`s joint goals and plans. Dynamic, real-time environments add to the challenge, as ambiguities have to be resolved in real-time. The central hypothesismore » underlying the present work is that an explicit team-oriented perspective enables effective team tracking. This hypothesis is instantiated using the model tracing technology employed in tracking individual agents. Thus, to track team activities, team models are put to service. Team models are a concrete application of the joint intentions framework and enable an agent to track team activities, regardless of the agent`s being a collaborative participant or a non-participant in the team. To facilitate real-time ambiguity resolution with team models: (i) aspects of tracking are cast as constraint satisfaction problems to exploit constraint propagation techniques; and (ii) a cost minimality criterion is applied to constrain tracking search. Empirical results from two separate tasks in real-world, dynamic environments one collaborative and one competitive - are provided.« less

Perceiving the agency of harmful agents: A test of dehumanization versus moral typecasting accounts.

PubMed

Khamitov, Mansur; Rotman, Jeff D; Piazza, Jared

2016-01-01

It is clear that harmful agents are targets of severe condemnation, but it is much less clear how perceivers conceptualize the agency of harmful agents. The current studies tested two competing predictions made by moral typecasting theory and the dehumanization literature. Across six studies, harmful agents were perceived to possess less agency than neutral (non-offending) and benevolent agents, consistent with a dehumanization perspective but inconsistent with the assumptions of moral typecasting theory. This was observed for human targets (Studies 1-2b and 4-5) and corporations (Study 3), and across various gradations of harmfulness (Studies 3 and 4). Importantly, denial of agency to harmful agents occurred even when controlling for perceptions of the agent's likeability (Studies 2a and 2b) and while using two different operationalizations of agency (Study 2a). Study 5 showed that harmful agents are denied agency primarily through an inferential process, and less through motivations to see the agent punished. Across all six studies, harmful agents were deemed less worthy of moral standing as a consequence of their harmful conduct and this reduction in moral standing was mediated through reductions in agency. Our findings clarify a current tension in the moral cognition literature, which have direct implications for the moral typecasting framework. Copyright © 2015 Elsevier B.V. All rights reserved.

Alpha-beta coordination method for collective search

DOEpatents

Goldsmith, Steven Y.

2002-01-01

The present invention comprises a decentralized coordination strategy called alpha-beta coordination. The alpha-beta coordination strategy is a family of collective search methods that allow teams of communicating agents to implicitly coordinate their search activities through a division of labor based on self-selected roles and self-determined status. An agent can play one of two complementary roles. An agent in the alpha role is motivated to improve its status by exploring new regions of the search space. An agent in the beta role is also motivated to improve its status, but is conservative and tends to remain aggregated with other agents until alpha agents have clearly identified and communicated better regions of the search space. An agent can select its role dynamically based on its current status value relative to the status values of neighboring team members. Status can be determined by a function of the agent's sensor readings, and can generally be a measurement of source intensity at the agent's current location. An agent's decision cycle can comprise three sequential decision rules: (1) selection of a current role based on the evaluation of the current status data, (2) selection of a specific subset of the current data, and (3) determination of the next heading using the selected data. Variations of the decision rules produce different versions of alpha and beta behaviors that lead to different collective behavior properties.

Use of second-generation antipsychotic agents for sleep and sedation: a provider survey.

PubMed

Hermes, Eric D A; Sernyak, Michael; Rosenheck, Robert

2013-04-01

Anecdotal evidence suggests that second-generation antipsychotic agents are increasingly used to treat sleep problems. This study sought to quantify the proportion of new prescriptions for second-generation antipsychotic agents started for sleep/sedation and the correlates of such use. A cross-sectional survey of provider decision making at the time second-generation antipsychotic agents were prescribed, documenting the reasons for the medication, patient demographics, psychiatric and medical diagnoses, patient health characteristics, and provider background. A single Veterans Affairs Medical Center over a 20-month period. Prescribers of second-generation antipsychotic agents. N/A. Seven hundred seven (32.2%) of 2,613 surveys indicated sleep/sedation was at least one reason for using a second-generation anti-psychotic agent, whereas for 266 (12.1%) it was the only reason. Quetiapine was most frequently prescribed overall as well as for sleep/sedation (47.0% and 73.6% respectively). Second-generation antipsychotic agent use for sleep/sedation was unrelated to sociodemographic characteristics, least likely in patients with schizophrenia or bipolar disorder, and most likely as a newly started second-generation antipsychotic agent. Sleep/sedation is a common reason given for new prescriptions of second-generation antipsychotic agents. Quetiapine is most frequently used for this purpose. A greater understanding of why providers use second-generation antipsychotic agents rather than safer and less costly alternatives for sleep problems may advance the development of interventions to reduce adverse effects.

Reusable Autonomy

NASA Technical Reports Server (NTRS)

Truszkowski, Walt; Obenschain, Arthur F. (Technical Monitor)

2002-01-01

Currently, spacecraft ground systems have a well defined and somewhat standard architecture and operations concept. Based on domain analysis studies of various control centers conducted over the years it is clear that ground systems have core capabilities and functionality that are common across all ground systems. This observation alone supports the realization of reuse. Additionally, spacecraft ground systems are increasing in their ability to do things autonomously. They are being engineered using advanced expert systems technology to provide automated support for operators. A clearer understanding of the possible roles of agent technology is advancing the prospects of greater autonomy for these systems. Many of their functional and management tasks are or could be supported by applied agent technology, the dynamics of the ground system's infrastructure could be monitored by agents, there are intelligent agent-based approaches to user-interfaces, etc. The premise of this paper is that the concepts associated with software reuse, applicable in consideration of classically-engineered ground systems, can be updated to address their application in highly agent-based realizations of future ground systems. As a somewhat simplified example consider the following situation, involving human agents in a ground system context. Let Group A of controllers be working on Mission X. They are responsible for the command, control and health and safety of the Mission X spacecraft. Let us suppose that mission X successfully completes it mission and is turned off. Group A could be dispersed or perhaps move to another Mission Y. In this case there would be reuse of the human agents from Mission X to Mission Y. The Group A agents perform their well-understood functions in a somewhat but related context. There will be a learning or familiarization process that the group A agents go through to make the new context, determined by the new Mission Y, understood. This simplified scenario highlights some of the major issues that need to be addressed when considering the situation where Group A is composed of software-based agents (not their human counterparts) and they migrate from one mission support system to another. This paper will address: - definition of an agent architecture appropriate to support reuse; - identification of non-mission-specific agent capabilities required; - appropriate knowledge representation schemes for mission-specific knowledge; - agent interface with mission-specific knowledge (a type of Learning); development of a fully-operational group of cooperative software agents for ground system support; architecture and operation of a repository of reusable agents that could be the source of intelligent components for realizing an autonomous (or nearly autonomous) agent-based ground system, and an agent-based approach to repository management and operation (an intelligent interface for human use of the repository in a ground-system development activity).

Timing and Characteristics of Cumulative Evidence Available on Novel Therapeutic Agents Receiving Food and Drug Administration Accelerated Approval.

PubMed

Naci, Huseyin; Wouters, Olivier J; Gupta, Radhika; Ioannidis, John P A

2017-06-01

Policy Points: Randomized trials-the gold standard of evaluating effectiveness-constitute a small minority of existing evidence on agents given accelerated approval. One-third of randomized trials are in therapeutic areas outside of FDA approval and less than half evaluate the therapeutic benefits of these agents but use them instead as common backbone treatments. Agents receiving accelerated approval are often tested concurrently in several therapeutic areas. For most agents, no substantial time lag is apparent between the average start dates of randomized trials evaluating their effectiveness and those using them as part of background therapies. There appears to be a tendency for therapeutic agents receiving accelerated approval to quickly become an integral component of standard treatment, despite potential shortcomings in their evidence base. Therapeutic agents treating serious conditions are eligible for Food and Drug Administration (FDA) accelerated approval. The clinical evidence accrued on agents receiving accelerated approval has not been systematically evaluated. Our objective was to assess the timing and characteristics of available studies. We first identified clinical studies of novel therapeutic agents receiving accelerated approval. We then (1) categorized those studies as randomized or nonrandomized, (2) explored whether they evaluated the FDA-approved indications, and (3) documented the available treatment comparisons. We also meta-analyzed the difference in start times between randomized studies that (1) did or did not evaluate approved indications and (2) were or were not designed to evaluate the agent's effectiveness. In total, 37 novel therapeutic agents received accelerated approval between 2000 and 2013. Our search of ClinicalTrials.gov identified 7,757 studies, which included 1,258,315 participants. Only one-third of identified studies were randomized controlled trials. Of 1,631 randomized trials with advanced recruitment status, 906 were conducted in therapeutic areas for which agents received initial accelerated approval, 202 were in supplemental indications, and 523 were outside approved indications. Only 411 out of 906 (45.4%) trials were designed to test the effectiveness of agents that received accelerated approval ("evaluation" trials); others used these agents as common background treatment in both arms ("background" trials). There was no detectable lag between average start times of trials conducted within and outside initially approved indications. Evaluation trials started on average 1.52 years (95% CI: 0.87 to 2.17) earlier than background trials. Cumulative evidence on agents with accelerated approvals has major limitations. Most clinical studies including these agents are small and nonrandomized, and about a third are conducted in unapproved areas, typically concurrently with those conducted in approved areas. Most randomized trials including these therapeutic agents are not designed to directly evaluate their clinical benefits but to incorporate them as standard treatment. © 2017 Milbank Memorial Fund.

Building an adaptive agent to monitor and repair the electrical power system of an orbital satellite

NASA Technical Reports Server (NTRS)

Tecuci, Gheorghe; Hieb, Michael R.; Dybala, Tomasz

1995-01-01

Over several years we have developed a multistrategy apprenticeship learning methodology for building knowledge-based systems. Recently we have developed and applied our methodology to building intelligent agents. This methodology allows a subject matter expert to build an agent in the same way in which the expert would teach a human apprentice. The expert will give the agent specific examples of problems and solutions, explanations of these solutions, or supervise the agent as it solves new problems. During such interactions, the agent learns general rules and concepts, continuously extending and improving its knowledge base. In this paper we present initial results on applying this methodology to build an intelligent adaptive agent for monitoring and repair of the electrical power system of an orbital satellite, stressing the interaction with the expert during apprenticeship learning.

The development of bis(hydroxymethyl)pyrrole analogs as bifunctional DNA cross-linking agents and their chemotherapeutic potential.

PubMed

Su, Tsann-Long; Lee, Te-Chang; Kakadiya, Rajesh

2013-11-01

Bifunctional DNA cross-linking agents are widely used as chemotherapeutic agents in clinics. The advance in the development of these agents as potential antitumor agents has generated various types of bis(hydroxymethyl)pyrrole analogs. In order to develop highly effective anticancer agents, it is necessary to understand the chemophysical properties, structure-activity relationships, therapeutic potency, toxicity/safety, and pharmacokinetics of these DNA cross-linking agents. This review presents an overview of the recent advances in developing various types of bis(hydroxymethyl)pyrrole analogs with potential antitumor activity to provide more information for future drug design and strategies for combination chemotherapy. The rational drug design, chemical syntheses, antitumor activity, mechanism of action, and development of combined chemotherapy regimens, including a DNA repair inhibitor, are discussed. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Protecting software agents from malicious hosts using quantum computing

NASA Astrophysics Data System (ADS)

Reisner, John; Donkor, Eric

2000-07-01

We evaluate how quantum computing can be applied to security problems for software agents. Agent-based computing, which merges technological advances in artificial intelligence and mobile computing, is a rapidly growing domain, especially in applications such as electronic commerce, network management, information retrieval, and mission planning. System security is one of the more eminent research areas in agent-based computing, and the specific problem of protecting a mobile agent from a potentially hostile host is one of the most difficult of these challenges. In this work, we describe our agent model, and discuss the capabilities and limitations of classical solutions to the malicious host problem. Quantum computing may be extremely helpful in addressing the limitations of classical solutions to this problem. This paper highlights some of the areas where quantum computing could be applied to agent security.

Towards Cooperative Predictive Data Mining in Competitive Environments

NASA Astrophysics Data System (ADS)

Lisý, Viliam; Jakob, Michal; Benda, Petr; Urban, Štěpán; Pěchouček, Michal

We study the problem of predictive data mining in a competitive multi-agent setting, in which each agent is assumed to have some partial knowledge required for correctly classifying a set of unlabelled examples. The agents are self-interested and therefore need to reason about the trade-offs between increasing their classification accuracy by collaborating with other agents and disclosing their private classification knowledge to other agents through such collaboration. We analyze the problem and propose a set of components which can enable cooperation in this otherwise competitive task. These components include measures for quantifying private knowledge disclosure, data-mining models suitable for multi-agent predictive data mining, and a set of strategies by which agents can improve their classification accuracy through collaboration. The overall framework and its individual components are validated on a synthetic experimental domain.

New approaches in agent-based modeling of complex financial systems

NASA Astrophysics Data System (ADS)

Chen, Ting-Ting; Zheng, Bo; Li, Yan; Jiang, Xiong-Fei

2017-12-01

Agent-based modeling is a powerful simulation technique to understand the collective behavior and microscopic interaction in complex financial systems. Recently, the concept for determining the key parameters of agent-based models from empirical data instead of setting them artificially was suggested. We first review several agent-based models and the new approaches to determine the key model parameters from historical market data. Based on the agents' behaviors with heterogeneous personal preferences and interactions, these models are successful in explaining the microscopic origination of the temporal and spatial correlations of financial markets. We then present a novel paradigm combining big-data analysis with agent-based modeling. Specifically, from internet query and stock market data, we extract the information driving forces and develop an agent-based model to simulate the dynamic behaviors of complex financial systems.

Multi-Agent Strategic Modeling in a Specific Environment

NASA Astrophysics Data System (ADS)

Gams, Matjaz; Bezek, Andraz

Multi-agent modeling in ambient intelligence (AmI) is concerned with the following task [19]: How can external observations of multi-agent systems in the ambient be used to analyze, model, and direct agent behavior? The main purpose is to obtain knowledge about acts in the environment thus enabling proper actions of the AmI systems [1]. Analysis of such systems must thus capture complex world state representation and asynchronous agent activities. Instead of studying basic numerical data, researchers often use more complex data structures, such as rules and decision trees. Some methods are extremely useful when characterizing state space, but lack the ability to clearly represent temporal state changes occurred by agent actions. To comprehend simultaneous agent actions and complex changes of state space, most often a combination of graphical and symbolical representation performs better in terms of human understanding and performance.

Design and Implementation of Context-Aware Musuem Guide Agents

NASA Astrophysics Data System (ADS)

Satoh, Ichiro

This paper presents an agent-based system for building and operating context-aware services in public spaces, including museums. The system provides users with agents and detects the locations of users and deploys location-aware user-assistant agents at computers near the their current locations by using active RFID-tags. When a visitor moves between exhibits in a museum, this dynamically deploys his/her agent at the computers close to the exhibits by using mobile agent technology. It annotates the exhibits in his/her personalized form and navigate him/her user to the next exhibits along his/her routes. It also introduces user movement as a natural approach to interacting between users and agents. To demonstrate the utility and effectiveness of the system, we constructed location/user-aware visitor-guide services and experimented them for two weeks in a public museum.

Research on Production Scheduling System with Bottleneck Based on Multi-agent

NASA Astrophysics Data System (ADS)

Zhenqiang, Bao; Weiye, Wang; Peng, Wang; Pan, Quanke

Aimed at the imbalance problem of resource capacity in Production Scheduling System, this paper uses Production Scheduling System based on multi-agent which has been constructed, and combines the dynamic and autonomous of Agent; the bottleneck problem in the scheduling is solved dynamically. Firstly, this paper uses Bottleneck Resource Agent to find out the bottleneck resource in the production line, analyses the inherent mechanism of bottleneck, and describes the production scheduling process based on bottleneck resource. Bottleneck Decomposition Agent harmonizes the relationship of job's arrival time and transfer time in Bottleneck Resource Agent and Non-Bottleneck Resource Agents, therefore, the dynamic scheduling problem is simplified as the single machine scheduling of each resource which takes part in the scheduling. Finally, the dynamic real-time scheduling problem is effectively solved in Production Scheduling System.

A Sequence Mining Method to Predict the Bidding Strategy of Trading Agents

NASA Astrophysics Data System (ADS)

Nikolaidou, Vivia; Mitkas, Pericles A.

In this work, we describe the process used in order to predict the bidding strategy of trading agents. This was done in the context of the Reverse TAC, or CAT, game of the Trading Agent Competition. In this game, a set of trading agents, buyers or sellers, are provided by the server and they trade their goods in one of the markets operated by the competing agents. Better knowledge of the strategy of the trading agents will allow a market maker to adapt its incentives and attract more agents to its own market. Our prediction was based on the time series of the traders’ past bids, taking into account the variation of each bid compared to its history. The results proved to be of satisfactory accuracy, both in the game’s context and when compared to other existing approaches.

Mobile Agents: A Distributed Voice-Commanded Sensory and Robotic System for Surface EVA Assistance

NASA Technical Reports Server (NTRS)

Clancey, William J.; Sierhuis, Maarten; Alena, Rick; Crawford, Sekou; Dowding, John; Graham, Jeff; Kaskiris, Charis; Tyree, Kim S.; vanHoof, Ronnie

2003-01-01

A model-based, distributed architecture integrates diverse components in a system designed for lunar and planetary surface operations: spacesuit biosensors, cameras, GPS, and a robotic assistant. The system transmits data and assists communication between the extra-vehicular activity (EVA) astronauts, the crew in a local habitat, and a remote mission support team. Software processes ("agents"), implemented in a system called Brahms, run on multiple, mobile platforms, including the spacesuit backpacks, all-terrain vehicles, and robot. These "mobile agents" interpret and transform available data to help people and robotic systems coordinate their actions to make operations more safe and efficient. Different types of agents relate platforms to each other ("proxy agents"), devices to software ("comm agents"), and people to the system ("personal agents"). A state-of-the-art spoken dialogue interface enables people to communicate with their personal agents, supporting a speech-driven navigation and scheduling tool, field observation record, and rover command system. An important aspect of the engineering methodology involves first simulating the entire hardware and software system in Brahms, and then configuring the agents into a runtime system. Design of mobile agent functionality has been based on ethnographic observation of scientists working in Mars analog settings in the High Canadian Arctic on Devon Island and the southeast Utah desert. The Mobile Agents system is developed iteratively in the context of use, with people doing authentic work. This paper provides a brief introduction to the architecture and emphasizes the method of empirical requirements analysis, through which observation, modeling, design, and testing are integrated in simulated EVA operations.

Inconsistency as a diagnostic tool in a society of intelligent agents.

PubMed

McShane, Marjorie; Beale, Stephen; Nirenburg, Sergei; Jarrell, Bruce; Fantry, George

2012-07-01

To use the detection of clinically relevant inconsistencies to support the reasoning capabilities of intelligent agents acting as physicians and tutors in the realm of clinical medicine. We are developing a cognitive architecture, OntoAgent, that supports the creation and deployment of intelligent agents capable of simulating human-like abilities. The agents, which have a simulated mind and, if applicable, a simulated body, are intended to operate as members of multi-agent teams featuring both artificial and human agents. The agent architecture and its underlying knowledge resources and processors are being developed in a sufficiently generic way to support a variety of applications. We show how several types of inconsistency can be detected and leveraged by intelligent agents in the setting of clinical medicine. The types of inconsistencies discussed include: test results not supporting the doctor's hypothesis; the results of a treatment trial not supporting a clinical diagnosis; and information reported by the patient not being consistent with observations. We show the opportunities afforded by detecting each inconsistency, such as rethinking a hypothesis, reevaluating evidence, and motivating or teaching a patient. Inconsistency is not always the absence of the goal of consistency; rather, it can be a valuable trigger for further exploration in the realm of clinical medicine. The OntoAgent cognitive architecture, along with its extensive suite of knowledge resources an processors, is sufficient to support sophisticated agent functioning such as detecting clinically relevant inconsistencies and using them to benefit patient-centered medical training and practice. Copyright © 2012 Elsevier B.V. All rights reserved.

Proceedings of the Agent 2002 Conference on Social Agents : Ecology, Exchange, and Evolution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Macal, C., ed.; Sallach, D., ed.

2003-04-10

Welcome to the ''Proceedings'' of the third in a series of agent simulation conferences cosponsored by Argonne National Laboratory and The University of Chicago. The theme of this year's conference, ''Social Agents: Ecology, Exchange and Evolution'', was selected to foster the exchange of ideas on some of the most important social processes addressed by agent simulation models, namely: (1) The translation of ecology and ecological constraints into social dynamics; (2) The role of exchange processes, including the peer dependencies they create; and (3) The dynamics by which, and the attractor states toward which, social processes evolve. As stated in themore » ''Call for Papers'', throughout the social sciences, the simulation of social agents has emerged as an innovative and powerful research methodology. The promise of this approach, however, is accompanied by many challenges. First, modeling complexity in agents, environments, and interactions is non-trivial, and these representations must be explored and assessed systematically. Second, strategies used to represent complexities are differentially applicable to any particular problem space. Finally, to achieve sufficient generality, the design and experimentation inherent in agent simulation must be coupled with social and behavioral theory. Agent 2002 provides a forum for reviewing the current state of agent simulation scholarship, including research designed to address such outstanding issues. This year's conference introduces an extensive range of domains, models, and issues--from pre-literacy to future projections, from ecology to oligopolistic markets, and from design to validation. Four invited speakers highlighted major themes emerging from social agent simulation.« less

Interfacial Stacks of Polymeric Nanofilms on Soft Biological Surfaces that Release Multiple Agents.

PubMed

Herron, Maggie; Schurr, Michael J; Murphy, Christopher J; McAnulty, Jonathan F; Czuprynski, Charles J; Abbott, Nicholas L

2016-10-03

We report a general and facile method that permits the transfer (stacking) of multiple independently fabricated and nanoscopically thin polymeric films, each containing a distinct bioactive agent, onto soft biomedically relevant surfaces (e.g., collagen-based wound dressings). By using polyelectrolyte multilayer films (PEMs) formed from poly(allyl amine hydrochloride) and poly(acrylic acid) as representative polymeric nanofilms and micrometer-thick water-soluble poly(vinyl alcohol) sacrificial films to stack the PEMs, we demonstrate that it is possible to create stacked polymeric constructs containing multiple bioactive agents (e.g., antimicrobial and antibiofilm agents) on soft and chemically complex surfaces onto which PEMs cannot be routinely transferred by stamping. We illustrate the characteristics and merits of the approach by fabricating stacks of Ga 3+ (antibiofilm agent)- and Ag + (antimicrobial agent)-loaded PEMs as prototypical examples of agent-containing PEMs and demonstrate that the stacked PEMs incorporate precise loadings of the agents and provide flexibility in terms of tuning release rates. Specifically, we show that simultaneous release of Ga 3+ and Ag + from the stacked PEMs on collagen-based wound dressings can lead to synergistic effects on bacteria, killing and dispersing biofilms formed by Pseudomonas aeruginosa (two strains: ATCC 27853 and MPAO1) at sufficiently low loadings of agents such that cytotoxic effects on mammalian cells are avoided. The approach is general (a wide range of bioactive agents other than Ga 3+ and Ag + can be incorporated into PEMs), and the modular nature of the approach potentially allows end-user functionalization of soft biological surfaces for programmed release of multiple bioactive agents.

The formation of continuous opinion dynamics based on a gambling mechanism and its sensitivity analysis

NASA Astrophysics Data System (ADS)

Zhu, Yueying; Alexandre Wang, Qiuping; Li, Wei; Cai, Xu

2017-09-01

The formation of continuous opinion dynamics is investigated based on a virtual gambling mechanism where agents fight for a limited resource. We propose a model with agents holding opinions between -1 and 1. Agents are segregated into two cliques according to the sign of their opinions. Local communication happens only when the opinion distance between corresponding agents is no larger than a pre-defined confidence threshold. Theoretical analysis regarding special cases provides a deep understanding of the roles of both the resource allocation parameter and confidence threshold in the formation of opinion dynamics. For a sparse network, the evolution of opinion dynamics is negligible in the region of low confidence threshold when the mindless agents are absent. Numerical results also imply that, in the presence of economic agents, high confidence threshold is required for apparent clustering of agents in opinion. Moreover, a consensus state is generated only when the following three conditions are satisfied simultaneously: mindless agents are absent, the resource is concentrated in one clique, and confidence threshold tends to a critical value(=1.25+2/ka ; k_a>8/3 , the average number of friends of individual agents). For fixed a confidence threshold and resource allocation parameter, the most chaotic steady state of the dynamics happens when the fraction of mindless agents is about 0.7. It is also demonstrated that economic agents are more likely to win at gambling, compared to mindless ones. Finally, the importance of three involved parameters in establishing the uncertainty of model response is quantified in terms of Latin hypercube sampling-based sensitivity analysis.

For whom will the Bayesian agents vote?

NASA Astrophysics Data System (ADS)

Caticha, Nestor; Cesar, Jonatas; Vicente, Renato

2015-04-01

Within an agent-based model where moral classifications are socially learned, we ask if a population of agents behaves in a way that may be compared with conservative or liberal positions in the real political spectrum. We assume that agents first experience a formative period, in which they adjust their learning style acting as supervised Bayesian adaptive learners. The formative phase is followed by a period of social influence by reinforcement learning. By comparing data generated by the agents with data from a sample of 15000 Moral Foundation questionnaires we found the following. 1. The number of information exchanges in the formative phase correlates positively with statistics identifying liberals in the social influence phase. This is consistent with recent evidence that connects the dopamine receptor D4-7R gene, political orientation and early age social clique size. 2. The learning algorithms that result from the formative phase vary in the way they treat novelty and corroborative information with more conservative-like agents treating it more equally than liberal-like agents. This is consistent with the correlation between political affiliation and the Openness personality trait reported in the literature. 3. Under the increase of a model parameter interpreted as an external pressure, the statistics of liberal agents resemble more those of conservative agents, consistent with reports on the consequences of external threats on measures of conservatism. We also show that in the social influence phase liberal-like agents readapt much faster than conservative-like agents when subjected to changes on the relevant set of moral issues. This suggests a verifiable dynamical criterium for attaching liberal or conservative labels to groups.

In vitro Comparative Evaluation of Tensile Bond Strength of 6(th), 7(th) and 8(th) Generation Dentin Bonding Agents.

PubMed

Kamble, Suresh S; Kandasamy, Baburajan; Thillaigovindan, Ranjani; Goyal, Nitin Kumar; Talukdar, Pratim; Seal, Mukut

2015-05-01

Newer dentin bonding agents were developed to improve the quality of composite restoration and to reduce time consumption in its application. The aim of the present study was to evaluate tensile bond strength of 6(th), 7(th) and 8(th) generation bonding agents by in vitro method. Selected 60 permanent teeth were assigned into 20 in each group (Group I: 6(th) generation bonding agent-Adper SE plus 3M ESPE, Group II: 7(th) generation bonding agent-G-Bond GC Corp Japan and Group III: 8(th) generation dentin adhesives-FuturaBond, DC, Voco, Germany). With high-speed diamond disc, coronal dentin was exposed, and selected dentin bonding agents were applied, followed by composite restoration. All samples were saved in saline for 24 h and tensile bond strength testing was done using a universal testing machine. The obtained data were tabulated and statistically analyzed using ANOVA test. The tensile bond strength readings for 6(th) generation bonding agent was 32.2465, for 7(th) generation was 31.6734, and for 8(th)-generation dentine bonding agent was 34.74431. The highest tensile bond strength was seen in 8(th) generation bonding agent compared to 6(th) and 7(th) generation bonding agents. From the present study it can be conclude that 8(th) generation dentine adhesive (Futura DC, Voco, Germany) resulted in highest tensile bond strength compared to 6(th) (Adper SE plus, 3M ESPE) and 7(th) generation (G-Bond) dentin bonding agents.

Software agents and the route to the information economy

PubMed Central

Kephart, Jeffrey O.

2002-01-01

Humans are on the verge of losing their status as the sole economic species on the planet. In private laboratories and in the Internet laboratory, researchers and developers are creating a variety of autonomous economically motivated software agents endowed with algorithms for maximizing profit or utility. Many economic software agents will function as miniature businesses, purchasing information inputs from other agents, combining and refining them into information goods and services, and selling them to humans or other agents. Their mutual interactions will form the information economy: a complex economic web of information goods and services that will adapt to the ever-changing needs of people and agents. The information economy will be the largest multiagent system ever conceived and an integral part of the world's economy. I discuss a possible route toward this vision, beginning with present-day Internet trends suggesting that agents will charge one another for information goods and services. Then, to establish that agents can be competent price setters, I describe some laboratory experiments pitting software bidding agents against human bidders. The agents' superior performance suggests they will be used on a broad scale, which in turn suggests that interactions among agents will become frequent and significant. How will this affect macroscopic economic behavior? I describe some interesting phenomena that my colleagues and I have observed in simulations of large populations of automated buyers and sellers, such as price war cycles. I conclude by discussing fundamental scientific challenges that remain to be addressed as we journey toward the information economy. PMID:12011399

14 CFR 221.11 - Agent.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 14 Aeronautics and Space 4 2014-01-01 2014-01-01 false Agent. 221.11 Section 221.11 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS TARIFFS Who is Authorized To Issue and File Tariffs § 221.11 Agent. An agent may issue and file...

14 CFR 221.11 - Agent.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 14 Aeronautics and Space 4 2013-01-01 2013-01-01 false Agent. 221.11 Section 221.11 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS TARIFFS Who is Authorized To Issue and File Tariffs § 221.11 Agent. An agent may issue and file...

14 CFR 221.11 - Agent.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 14 Aeronautics and Space 4 2012-01-01 2012-01-01 false Agent. 221.11 Section 221.11 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS TARIFFS Who is Authorized To Issue and File Tariffs § 221.11 Agent. An agent may issue and file...

14 CFR 221.11 - Agent.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 14 Aeronautics and Space 4 2011-01-01 2011-01-01 false Agent. 221.11 Section 221.11 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS TARIFFS Who is Authorized To Issue and File Tariffs § 221.11 Agent. An agent may issue and file...

14 CFR 221.11 - Agent.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Agent. 221.11 Section 221.11 Aeronautics and Space OFFICE OF THE SECRETARY, DEPARTMENT OF TRANSPORTATION (AVIATION PROCEEDINGS) ECONOMIC REGULATIONS TARIFFS Who is Authorized To Issue and File Tariffs § 221.11 Agent. An agent may issue and file...

24 CFR 232.1011 - Management agents.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 24 Housing and Urban Development 2 2014-04-01 2014-04-01 false Management agents. 232.1011 Section... Management agents. (a) An operator or borrower may, with the prior written approval of HUD, execute a management agent agreement setting forth the duties and procedures for matters related to the management of...

24 CFR 232.1011 - Management agents.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 24 Housing and Urban Development 2 2013-04-01 2013-04-01 false Management agents. 232.1011 Section... Management agents. (a) An operator or borrower may, with the prior written approval of HUD, execute a management agent agreement setting forth the duties and procedures for matters related to the management of...

21 CFR 181.28 - Release agents.

Code of Federal Regulations, 2011 CFR

2011-04-01

... Release agents. Substances classified as release agents, when migrating from food-packaging material shall... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Release agents. 181.28 Section 181.28 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN...

19 CFR 201.15 - Attorneys or agents.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 19 Customs Duties 3 2013-04-01 2013-04-01 false Attorneys or agents. 201.15 Section 201.15 Customs Duties UNITED STATES INTERNATIONAL TRADE COMMISSION GENERAL RULES OF GENERAL APPLICATION Initiation and Conduct of Investigations § 201.15 Attorneys or agents. (a) In general. No register of attorneys or agents...

29 CFR 453.21 - Interests held in agents, brokers, and surety companies.

Code of Federal Regulations, 2012 CFR

2012-07-01

... any surety company in which any labor organization or any officer, agent, shop steward, or other..., in which any labor organization or any officer, agent, shop steward, or other representative of a... a substantial number of officers, agents, shop stewards, or other representatives of a labor...

29 CFR 453.21 - Interests held in agents, brokers, and surety companies.

Code of Federal Regulations, 2014 CFR

2014-07-01

... any surety company in which any labor organization or any officer, agent, shop steward, or other..., in which any labor organization or any officer, agent, shop steward, or other representative of a... a substantial number of officers, agents, shop stewards, or other representatives of a labor...

29 CFR 453.21 - Interests held in agents, brokers, and surety companies.

Code of Federal Regulations, 2013 CFR

2013-07-01

... any surety company in which any labor organization or any officer, agent, shop steward, or other..., in which any labor organization or any officer, agent, shop steward, or other representative of a... a substantial number of officers, agents, shop stewards, or other representatives of a labor...

An Active Learning Exercise for Introducing Agent-Based Modeling

ERIC Educational Resources Information Center

Pinder, Jonathan P.

2013-01-01

Recent developments in agent-based modeling as a method of systems analysis and optimization indicate that students in business analytics need an introduction to the terminology, concepts, and framework of agent-based modeling. This article presents an active learning exercise for MBA students in business analytics that demonstrates agent-based…

What Influences Agents to Pursue a Career in Extension?

ERIC Educational Resources Information Center

Arnold, Shannon; Place, Nick

2010-01-01

The qualitative study reported here explored why agricultural agents pursue an Extension career. A purposive sample was used to select twelve Florida agricultural agents. Interviews investigated positive and negative influences that affected agents' employment decisions. Grounded theory was used as the primary data analysis method (Strauss &…

21 CFR 181.28 - Release agents.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Release agents. 181.28 Section 181.28 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Release agents. Substances classified as release agents, when migrating from food-packaging material shall...

21 CFR 172.880 - Petrolatum.

Code of Federal Regulations, 2010 CFR

2010-04-01

... bakery products; as release agent and lubricant With white mineral oil, not to exceed 0.15 percent of bakery product. In confectionery; as release agent and as sealing and polishing agent Not to exceed 0.2 percent of confectionery. In dehydrated fruits and vegetables; as release agent Not to exceed 0.02 percent...

Hydroxypyridonate and hydroxypyrimidinone chelating agents

DOEpatents

Raymond, Kenneth N.; Doble, Daniel M.; Sunderland, Christopher J.; Thompson, Marlon

2005-01-25

The present invention provides hydroxypyridinone and hydroxypyrimidone chelating agents. Also provides are Gd(III) complexes of these agents, which are useful as contrast enhancing agents for magnetic resonance imaging. The invention also provides methods of preparing the compounds of the invention, as well as methods of using the compounds in magnetic resonance imaging applications.

Biodegradation of Organophosphate Chemical Warfare Agents by Activated Sludge

DTIC Science & Technology

2012-03-01

Holmstedt, B. (1963). Structure- activity relationships of the organophosphorus anticholinesterase agents. In: Koelle, G.B. (ed.), Handbuch...BIODEGRADATION OF ORGANOPHOSPHATE CHEMICAL WARFARE AGENTS BY ACTIVATED SLUDGE Steven J. Schuldt...AFIT/GES/ENV/12-M04 BIODEGRADATION OF ORGANOPHOSPHATE CHEMICAL WARFARE AGENTS BY ACTIVATED SLUDGE THESIS Presented to the

Market-Based Coordination and Auditing Mechanisms for Self-Interested Multi-Robot Systems

ERIC Educational Resources Information Center

Ham, MyungJoo

2009-01-01

We propose market-based coordinated task allocation mechanisms, which allocate complex tasks that require synchronized and collaborated services of multiple robot agents to robot agents, and an auditing mechanism, which ensures proper behaviors of robot agents by verifying inter-agent activities, for self-interested, fully-distributed, and…

Photoactivatable Lipid-based Nanoparticles as a Vehicle for Dual Agent Delivery | NCI Technology Transfer Center | TTC

Cancer.gov

Researchers at the National Cancer Institute (NCI) RNA Biology Laboratory have developed nanoparticles that can deliver an agent (i.e., therapeutic or imaging) and release the agent upon targeted photoactivation allowing for controlled temporal and localized release of the agent.

Agent-Based Learning Environments as a Research Tool for Investigating Teaching and Learning.

ERIC Educational Resources Information Center

Baylor, Amy L.

2002-01-01

Discusses intelligent learning environments for computer-based learning, such as agent-based learning environments, and their advantages over human-based instruction. Considers the effects of multiple agents; agents and research design; the use of Multiple Intelligent Mentors Instructing Collaboratively (MIMIC) for instructional design for…

46 CFR 315.5 - Appointment of agents.

Code of Federal Regulations, 2013 CFR

2013-10-01

... Agent by MARAD, the contracting office shall transmit the Service Agreement or Ship Manager contract to... Agreement and Ship Manager Contract may be obtained from the Office of Acquisition at the address appearing... appointment as General Agent, Berth Agent or Ship Manager may be obtained from, and inquiries and other...

46 CFR 315.5 - Appointment of agents.

Code of Federal Regulations, 2012 CFR

2012-10-01

... Agent by MARAD, the contracting office shall transmit the Service Agreement or Ship Manager contract to... Agreement and Ship Manager Contract may be obtained from the Office of Acquisition at the address appearing... appointment as General Agent, Berth Agent or Ship Manager may be obtained from, and inquiries and other...

46 CFR 315.5 - Appointment of agents.

Code of Federal Regulations, 2014 CFR

2014-10-01

... Agent by MARAD, the contracting office shall transmit the Service Agreement or Ship Manager contract to... Agreement and Ship Manager Contract may be obtained from the Office of Acquisition at the address appearing... appointment as General Agent, Berth Agent or Ship Manager may be obtained from, and inquiries and other...