Evaluation of prescription opioids using operant-based pain measures in rats.

Opioids are the most effective compounds available for the relief of pain, yet there are a number of side effects that are of great concern to clinicians. For example, opioids are powerful reinforcers, and the treatment of pain using opioids could lead to the development of addiction. In addition, there is an increasing body of literature demonstrating that the repeated administration of opioids could lead to a phenomenon called opioid-induced hyperalgesia (i.e., increased sensitivity to painful stimulation). Studies examining these potential adverse effects are necessary in the development of novel analgesics. Furthermore, most studies of pain sensitivity and pain relief use reflex-based procedures to identify analgesics; however, it is argued here that operant-based procedures provide measures that are more analogous to the human condition (i.e., the mechanisms of pain are similar to those in humans) and should be useful in the assessment of novel analgesics. A series of studies examining the effects of opioids and the influence of variables such as age are discussed to demonstrate the utility of this approach. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Molecular dynamics of the anti-fluorescein 4-4-20 antigen-binding fragment. 2. Time-resolved fluorescence spectroscopy

Time-resolved fluorescence experiments were performed to investigate the dynamic aspects of the antigen-binding fragment (Fab) of a high-affinity monoclonal antibody (4-4-20) which binds the fluorescent hapten fluorescein. Both the unliganded Fab and a complex of the Fab with a nonfluorescent analog of fluorescein (fluoresceinamine, FLM) were examined. A fluorescence polarization probe [5-[[2-[(iodoacetyl)amino]ethyl]amino]naphthalene-1-sulfonic acid, AEDANS] was covalently attached to the C-terminus of the Fab. Experiments were performed at three different temperatures (10, 25, and 35 degrees C), and phase-modulation data sets were collected for five different molar ratios of FLM to Fab at each temperature. Global analyses were then used to extract values for fluorescence lifetime and rotational correlation time from these data. In the lifetime analysis the best fit was obtained when the emission of AEDANS was described by a Lorentzian distribution of lifetimes (tau = 15.6 ns, distribution width = 3.4 ns, both at 25 degrees C), which suggested that the probe experienced a heterogeneous environment. Anisotropy analyses suggested that two different rotational components were present. The first was attributed to the global motion of the Fab and exhibited a rotational correlation time (theta 1) of ca. 33 ns at 25 degrees C. This component was relatively unaffected by antigen binding. The second rotational component was attributed to the local or segmental motion within the Fab and exhibited a rotational correlation time (theta 2) of 1.1 ns at 25 degrees C. This value increased by more than 50% upon antigen binding, a result which was consistent with molecular dynamics simulations of the same Fab--fluorescein system [Lim & Herron (1995) Biochemistry 34, 6962-6974]. Furthermore, statistical analysis showed that this increase was significant at the 95% confidence level.     

Operation of an all-optical bistable device dependent upon incidentand transmitted optical power

The authors describe the optically bistable operation of an all-optical nonlinear Fabry-Perot etalon (NLFP) in which the power-dependent cavity phase shift has a contribution dependent on the power incident on the cavity. When the contributions have the same parity, the optically-bistable behavior is essentially the same as that seen in the now standard bistable NLFP (counterclockwise hysteresis in transmission). For opposite parity there is a range of relative strengths for which bistable operation cannot be obtained, but, outside of that range, bistable behavior having clockwise hysteresis in transmission is possible. This latter bistable behavior is demonstrated, with the NLFP being a GaAlAs laser diode amplifier driven by a similar diode laser. Low-frequency modulation of the laser power by direct variation of the laser drive current produced a small shift in laser wavelength proportional to the laser power, providing the cavity phase shift term proportional to the incident power, while the nonlinear refractive index of the NLFP provided the phase shift proportional to the transmitted power     

Coupling human mobility and social ties

Studies using massive, passively collected data from communication technologies have revealed many ubiquitous aspects of social networks, helping us understand and model social media, information diffusion and organizational dynamics. More recently, these data have come tagged with geographical information, enabling studies of human mobility patterns and the science of cities. We combine these two pursuits and uncover reproducible mobility patterns among social contacts. First, we introduce measures of mobility similarity and predictability and measure them for populations of users in three large urban areas. We find individuals'' visitations patterns are far more similar to and predictable by social contacts than strangers and that these measures are positively correlated with tie strength. Unsupervised clustering of hourly variations in mobility similarity identifies three categories of social ties and suggests geography is an important feature to contextualize social relationships. We find that the composition of a user''s ego network in terms of the type of contacts they keep is correlated with mobility behaviour. Finally, we extend a popular mobility model to include movement choices based on social contacts and compare its ability to reproduce empirical measurements with two additional models of mobility.     

Electrochemical metallization memories--fundamentals, applications, prospects

This review focuses on electrochemical metallization memory cells (ECM), highlighting their advantages as the next generation memories. In a brief introduction, the basic switching mechanism of ECM cells is described and the historical development is sketched. In a second part, the full spectra of materials and material combinations used for memory device prototypes and for dedicated studies are presented. In a third part, the specific thermodynamics and kinetics of nanosized electrochemical cells are described. The overlapping of the space charge layers is found to be most relevant for the cell properties at rest. The major factors determining the functionality of the ECM cells are the electrode reaction and the transport kinetics. Depending on electrode and/or electrolyte material electron transfer, electro-crystallization or slow diffusion under strong electric fields can be rate determining. In the fourth part, the major device characteristics of ECM cells are explained. Emphasis is placed on switching speed, forming and SET/RESET voltage, R(ON) to R(OFF) ratio, endurance and retention, and scaling potentials. In the last part, circuit design aspects of ECM arrays are discussed, including the pros and cons of active and passive arrays. In the case of passive arrays, the fundamental sneak path problem is described and as well as a possible solution by two anti-serial (complementary) interconnected resistive switches per cell. Furthermore, the prospects of ECM with regard to further scalability and the ability for multi-bit data storage are addressed.     

Sustained and sustaining continuing education for therapists.

Thirty-eight therapists who completed a 2-year continuing education program evaluated the effect of that program on how they conducted therapy and on themselves as individuals. The program differed from most continuing education offerings both in its ongoing nature and its emphasis on an interactive and dynamic use of material rather than on a purely didactic presentation. Participants described changes that they felt improved the quality of the therapeutic alliance, increased their ability to work effectively with difficult patients, and increased their self-awareness. This evaluation of the experience of a mature (over 10 years in operation) program is significant at a point when American Psychological Association (APA) is considering a broader conceptualization of continuing education models. These results also illustrate the importance of thoroughly evaluating the effect of continuing education. (PsycINFO Database Record (c) 2010 APA, all rights reserved)