Path Dependence in Decision-Making Processes: Exploring the Impact of Complexity under Increasing Returns

The development of path-dependent processes basically refers to positive feedback in terms of increasing returns as the main driving forces of such processes. Furthermore, path dependence can be affected by context factors, such as different degrees of complexity. Up to now, it has been unclear whether and how different settings of complexity impact path-dependent processes and the probability of lock-in. In this paper we investigate the relationship between environmental complexity and path dependence by means of an experimental study. By focusing on the mode of information load and decision quality in chronological sequences, the study explores the impact of complexity on decision-making processes. The results contribute to both the development of path-dependence theory and a better understanding of decision-making behavior under conditions of positive feedback. Since previous path research has mostly applied qualitative case-study research and (to a minor part) simulations, this paper makes a further contribution by establishing an experimental approach for research on path dependence.

Path Constitution Analysis: A Methodology for Understanding Path Dependence and Path Creation

Although an increasing number of studies of technological, institutional and organizational change refer to the concepts of path dependence and path creation, few attempts have been made to consider these concepts explicitly in their methodological accounts. This paper addresses this gap and contributes to the literature by developing a comprehensive methodology that originates from the concepts of path dependence and path creation – path constitution analysis (PCA) – and allows for the integration of multi-actor constellations on multiple levels of analysis within a process perspective. Based upon a longitudinal case study in the field of semiconductors, we illustrate PCA ‘in action’ as a template for other researchers and critically examine its adequacy. We conclude with implications for further path-oriented inquiries.

Single-Molecule Conductance of Functionalized Oligoynes: Length Dependence and Junction Evolution

We report a combined experimental and theoretical investigation of the length dependence and anchor group dependence of the electrical conductance of a series of oligoyne molecular wires in single-molecule junctions with gold contacts. Experimentally, we focus on the synthesis and properties of diaryloligoynes with n = 1, 2, and 4 triple bonds and the anchor dihydrobenzo[b]thiophene (BT). For comparison, we also explored the aurophilic anchor group cyano (CN), amino (NH2), thiol (SH), and 4-pyridyl (PY). Scanning tunneling microscopy break junction (STM-BJ) and mechanically controllable break junction (MCBJ) techniques are employed to investigate single-molecule conductance characteristics. The BT moiety is superior as compared to traditional anchoring groups investigated so far. BT-terminated oligoynes display a 100% probability of junction formation and possess conductance values which are the highest of the oligoynes studied and, moreover, are higher than other conjugated molecular wires of similar length. Density functional theory (DFT)-based calculations are reported for oligoynes with n = 1−4 triple bonds. Complete conductance traces and conductance distributions are computed for each family of molecules. The sliding of the anchor groups leads to oscillations in both the electrical conductance and the binding energies of the studied molecular wires. In agreement with experimental results, BT-terminated oligoynes are predicted to have a high electrical conductance. The experimental attenuation constants βH range between 1.7 nm−1 (CN) and 3.2 nm−1 (SH) and show the following trend: βH(CN) < βH(NH2) < βH(BT) < βH(PY) ≈ βH(SH). DFT-based calculations yield lower values, which range between 0.4 nm−1 (CN) and 2.2 nm−1 (PY).

Oligo(aryleneethynylene)s with Terminal Pyridyl Groups: Synthesis and Length Dependence of the Tunneling-to-Hopping Transition of Single-Molecule Conductances

The synthesis is reported of a new series of oligo(aryleneethynylene) (OAE) derivatives of up to ca. 6 nm in molecular length (OAE9) using iterative Pd-mediated Sonogashira cross-coupling methodology. The oligo-p-phenyleneethynylene cores of the molecular wires are functionalized at both termini with pyridyl units for attachment to gold leads. The molecular structures determined by single-crystal X-ray analysis are reported for OAE4, OAE5, OAE7, and OAE8a. The charge transport characteristics of derivatives OAE3–OAE9 in single-molecular junctions have been studied using the mechanically controlled break junction technique. The data demonstrate that the junction conductance decreases with increasing molecular length. A transition from coherent transport via tunneling to a hopping mechanism is found for OAE wires longer than ca. 3 nm.

The implementation of a tobacco dependence education curriculum in a Swiss Dental Hygiene School - an 8-year review

OBJECTIVE The aim of our investigation was to review the implementation of a comprehensive tobacco dependence education (TDE) curriculum at the Medi School of Dental Hygiene (MSDH), Bern, Switzerland, 2001-2008. METHODS In 2001, new forms to record patients' tobacco use history and willingness to quit were created for all the MSDH patients. In 2002, a new theoretically based tobacco dependence treatment protocol was implemented into the MSDH curriculum. Students received instruction on how to provide brief tobacco use dependence interventions as well as maintain detailed records of patient tobacco use and cessation interventions for every smoker at all dental hygiene visits. RESULTS In 2002, 17 lecture hours were added to the following subjects: pathology, periodontology, preventive dentistry, pharmacology and psychology. During the same time period, 2213 patients (56.9% women) have visited the MSDH. Smoking status was recorded in 85.7% of all the patients (30.2% smokers). Brief tobacco use interventions were recorded in 36.8% of all smokers while 7.6% of these have reported to quit smoking. CONCLUSIONS Overall, the new TDE curriculum was successfully implemented and accepted by the MSDH faculty. Applications in the clinical practice, however, may still be improved to better identify smokers and increase initial and follow-up interventions potentially leading to higher quit rates.

Implicit and explicit evaluations: a declaration of dependence

This section presents abstracts of three studies on how consumer choices can be influenced by the name letter effect of brands without decision makers being aware of this influence. The first paper examined whether making brand names similar to consumers' names increases the likelihood that consumers will choose the brand. One prediction is that people will prefer and be more likely to choose products or services whose names prominently feature the letters in their own first or last names. The results showed that subjects' preference rankings and evaluations of name letter matching brands were higher than those of non-name letter matching brands. The second paper tested the possibility of using subliminal priming to activate a concept that a persuasive communicator could take advantage of. To examine the idea, two experiments were presented. In the first experiment, participants' level of thirst were manipulated and then subliminally presented them with either thirst-related words or control words. While the manipulations had no effect on participants' self-reported, conscious ratings of thirst, there was a significant interactive effect of the two factors on how much of the drink provided in the taste test was consumed. In a second, follow up experiment, thirsty participants were subliminally presented with either thirst-related words or control words after which they viewed advertisements for two new sports beverages. In conclusion, the research demonstrates that under certain conditions, subliminal printing techniques can enhance persuasion. The third paper hypothesized that the lack of correlations between implicit and explicit evaluations is due to measurement error.

Time Dependence of Elimination of Different PEth Homologues in Alcoholics in Comparison with Social Drinkers

BACKGROUND: Phosphatidylethanol (PEth) is a direct marker of alcohol consumption, which has been known for almost 30 years. Each PEth molecule carries 2 fatty acids, which differ in chain length and degree of unsaturation. It is formed by means of phospholipase D in the presence of ethanol. Usually, this marker was used by quantification of the PEth homologue 16:0/18:1. The intention of this work was to get more information about the distribution and the quantity of the different PEth homologues. METHODS: Blood samples from 12 alcohol-dependent subjects were collected and analyzed during withdrawal therapy. For comparison, blood from 78 healthy social drinkers was also analyzed. PEth analysis was performed as follows: after liquid-liquid extraction, the homologues were separated on a Luna Phenyl Hexyl column, injected to an HPLC system (1100 system; Agilent) and identified by ESI-MS/MS (QTrap 2000; AB Sciex) using multiple reaction monitoring. RESULTS: PEth 16:0/18:1 is the major homologue comparing the area ratios of PEth homologues in blood samples from alcoholics. Additional prevalent homologues were PEth 16:0/18:2, 18:0/18:2, and 18:0/18:1. The homologues occurring in blood samples from alcoholics as well as from social drinkers were mostly the same, but differences among their distribution pattern were observed. CONCLUSIONS: In addition to the approach to quantitate the PEth homologue 16:0/18:1, this is a new and alternative proceeding for the differentiation between alcoholics and social drinkers using this alcohol consumption marker.

COCAINE DEPENDENCE: THE ROLE OF SEROTONIN GENES IN

Animal studies have shown that behavioral responses to cocaine-related cues are altered by serotonergic medications. The effects of pharmacological agents on serotonin receptors 2a (5-HT2A) and 2c (5-HT2C), have yielded results suggesting that selective 5-HT2A antagonists and 5-HT2C agonists promote the disruption of cocaine-associated memories. One measure of cocaine related cues in humans is attentional bias, in which cocaine dependent individuals show greater response latency for cocaine related words than neutral words. Data from our laboratory shows that cocaine dependent subjects have altered attentional bias compared to controls. The purpose of this thesis was to investigate the role of the serotonin system in attentional bias and impulsivity in cocaine dependent individuals. We focused on the serotonin transporter, serotonin receptors 2A and 2C and tryptophan hydroxylase 1 and 2 (TPH1 and TPH2). We predicted that attentional bias and impulsivity would be higher in cocaine dependent individuals who had lower serotonin function. In the current study, we found a significant association between TPH2 genotype and attentional bias for the second block of the cocaine Stroop task. There was also a significant association between average attentional bias and HTTLPR genotype in the cocaine dependent individuals. The HT2C receptor genotype and attentional bias in our study sample also showed a significant difference. We did not find a significant difference between the serotonin 2A receptor variants or the TPH1 variants and attentional bias in the cocaine dependent group. In conclusion, the current study suggests that serotonergic medications should be utilized as pharmacotherapeutic treatment for cocaine addiction. Our results indicate that TPH2, the serotonin transporter and 2C receptor should be targeted in such a way as to modulate both, leading to increased synaptic serotonin function.

Opioid dependence treatment: options in pharmacotherapy.

The development of effective treatments for opioid dependence is of great importance given the devastating consequences of the disease. Pharmacotherapies for opioid addiction include opioid agonists, partial agonists, opioid antagonists, and alpha-2-adrenergic agonists, which are targeted toward either detoxification or long-term agonist maintenance. Agonist maintenance therapy is currently the recommended treatment for opioid dependence due to its superior outcomes relative to detoxification. Detoxification protocols have limited long-term efficacy, and patient discomfort remains a significant therapy challenge. Buprenorphine's effectiveness relative to methadone remains a controversy and may be most appropriate for patients in need of low doses of agonist treatment. Buprenorphine appears superior to alpha-2 agonists, however, and office-based treatment with buprenorphine in the USA is gaining support. Studies of sustained-release formulations of naltrexone suggest improved effectiveness for retention and sustained abstinence; however, randomized clinical trials are needed.

A randomized, double-blind, placebo-controlled pilot study of naltrexone in outpatients with bipolar disorder and alcohol dependence.

BACKGROUND: Alcohol dependence is extremely common in patients with bipolar disorder and is associated with unfavorable outcomes including treatment nonadherence, violence, increased hospitalization, and decreased quality of life. While naltrexone is a standard treatment for alcohol dependence, no controlled trials have examined its use in patients with co-morbid bipolar disorder and alcohol dependence. In this pilot study, the efficacy of naltrexone in reducing alcohol use and on mood symptoms was assessed in bipolar disorder and alcohol dependence. METHODS: Fifty adult outpatients with bipolar I or II disorders and current alcohol dependence with active alcohol use were randomized to 12 weeks of naltrexone (50 mg/d) add-on therapy or placebo. Both groups received manual-driven cognitive behavioral therapy designed for patients with bipolar disorder and substance-use disorders. Drinking days and heavy drinking days, alcohol craving, liver enzymes, and manic and depressed mood symptoms were assessed. RESULTS: The 2 groups were similar in baseline and demographic characteristics. Naltrexone showed trends (p < 0.10) toward a greater decrease in drinking days (binary outcome), alcohol craving, and some liver enzyme levels than placebo. Side effects were similar in the 2 groups. Response to naltrexone was significantly related to medication adherence. CONCLUSIONS: Results suggest the potential value and acceptable tolerability of naltrexone for alcohol dependence in bipolar disorder patients. A larger trial is needed to establish efficacy.

Aggression, impulsivity and serotonin in drug dependence

Aggression, impulsivity, and central serotonergic function were evaluated in two groups of human volunteers; one group having a history of substance dependence (DRUG+) and another group with no drug use history (DRUG$-$). The hypothesis was that DRUG+ subjects would be more aggressive, more impulsive, and have attenuated serotonergic function. Results showed that DRUG+ subjects behaved more aggressively in a computer paradigm of aggression and also reported more aggression on questionnaires than DRUG$-$ subjects. In a computer paradigm of impulsivity, the DRUG+ group showed a lesser ability to delay gratification than the DRUG$-$ group in the last session of testing. The DRUG+ subjects also reported more venturesomeness and problems associated with low impulse control on questionnaires. Serotonergic function was measured through the neuroendocrine and hypothermic response to an orally administered serotonin (5-HT) agonist specific to the 5-HT$\rm\sb{1A}$ receptor subtype (ipsapirone). The neuroendocrine responses did not differ between DRUG$\pm$ groups, indicating no difference in the sensitivity of the presynaptic or postsynaptic 5-HT$\rm\sb{1A}$ receptors. An unexpected result was that the indicator hormone, cortisol, was at a lower baseline level in the DRUG+ group than the DRUG$-$ group. Lowered cortisol levels have been previously noted in children at high risk foul antisociality and future drug use. A principal components analysis including impulsivity, aggression, and serotonergic function measures produced three unique factors. The factors, Antisocial Tendency and Self-Control and Serotonergic Function combined to produce a significant regression equation explaining 36% of variability in the DRUG$\pm$ groups. These factors included measures of aggression, impulsivity, mood, and educational attainment. These results suggest that the current measures of aggression and impulsivity were predictive of a drug dependence disorder but that neuroendocrine function is not yet a useful indicator of drug dependence status. ^