Dark energy: recent observations and future prospects

Dark energy presents us with a challenging puzzle: understanding the new physics seen in the acceleration of the expansion of the Universe. Measurements using type-Ia supernovae (SNe) first detected this acceleration, and this approach remains the most direct route to studying the details of the Universe's expansion history that can teach us more about the nature of the dark energy. Such measurements are, however, extremely demanding in both precision and accuracy, since the different dark-energy models predict very small differences in the expansion history. While several cosmological probes may reach the required statistical uncertainties, the key measurement limit will be the systematic uncertainty. The supernova-measurement approach has the advantage of well-studied systematic uncertainties, allowing a next-generation experiment to be pursued. We briefly review the progress to date and examine the promise of future surveys with large numbers of SNe and well-bounded systematics.     

On the "general acceptance" of eyewitness testimony research: A new survey of the experts.

In light of recent advances, this study updated a prior survey of eyewitness experts (S. M. Kassin, P. C. Ellsworth, & V. L. Smith, 1989). Sixty-four psychologists were asked about their courtroom experiences and opinions on 30 eyewitness phenomena. By an agreement rate of at least 80%, there was a strong consensus that the following phenomena are sufficiently reliable to present in court: the wording of questions, lineup instructions, confidence malleability, mug-shot-induced bias, postevent information, child witness suggestibility, attitudes and expectations, hypnotic suggestibility, alcoholic intoxication, the cross-race bias, weapon focus, the accuracy–confidence correlation, the forgetting curve, exposure time, presentation format, and unconscious transference. Results also indicate that these experts set high standards before agreeing to testify. Despite limitations, these results should help to shape expert testimony so that it more accurately represents opinions in the scientific community. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive–behavioral therapy to reduce weight concerns improves smoking cessation outcome in weight-concerned women.

Women smokers concerned about weight gain (N?=?219) were randomly assigned to 1 of 3 adjunct treatments accompanying group smoking cessation counseling: (a) behavioral weight control to prevent weight gain (weight control); (b) cognitive–behavioral therapy (CBT) to directly reduce weight concern, in which dieting was discouraged; and (c) standard counseling alone (standard), in which weight gain was not explicitly addressed. Ten sessions were conducted over 7 weeks, and no medication was provided. Continuous abstinence was significantly higher at posttreatment and at 6 and 12 months of follow-up for CBT (56%, 28%, and 21%, respectively), but not for weight control (44%, 18%, and 13%, respectively), relative to standard (31%, 12%, and 9%, respectively). However, weight control, and to a lesser extent CBT, was associated with attenuation of negative mood after quitting. Prequit body mass index, but not change in weight or in weight concerns postquit, predicted cessation outcome at 1 year. In sum, CBT to reduce weight concerns, but not behavioral weight control counseling to prevent weight gain, improves smoking cessation outcome in weight-concerned women. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Performance of an 8×8 LiNbO3switch matrix as a gigahertz self-routing switching node

The performance of an LiNbO3 integrated-optic crossbar switch as a node in a gigahertz self-routing network is measured. Switch throughput supports 12.5 Gbit/s signals with a measured switching speed of 1.33 GHz. Crosstalk due to RF/ acousto-optic coupling and modulation depth are reported at 1.33 GHz. Optical self-routing of l00 Mbit/s information using the 8×8 switch is demonstrated.     

The λ-scheduler: A multiwavelength scheduling switch

We propose a new multiwavelength almost all-optical switch architecture called the λ-scheduler that uses wavelength division multiplexing (WDM) internally to fold the switch architecture in both the space and time domains to reduce the hardware complexity and to improve the signal characteristics through the switch. The λ-scheduler preserves the packet order for a given input-output pair, is consistent with virtual circuit switching, and when combined with appropriate connection and flow control protocols, provides lossless communication for bursty (or nonconstant rate) traffic, provided the traffic satisfies certain smoothness properties. The λ-scheduler uses novel scheduling and wavelength assignment algorithms, in conjunction with a series of feed-forward delay blocks, to avoid packet collisions within the switch or at the switch outputs. We present two implementations of the λ-scheduler when the number of internal wavelengths k equal the number of inputs (and outputs) N to the switch. In the compressed λ-scheduler, the N internal wavelengths are used to fold the architecture in the time domain, which reduces the total number of delay blocks for the switch by 2N log N. In the collapsed λ-scheduler, the N internal wavelengths are used to fold the architecture in the space domain, which reduces the number of delay blocks and total fiber length used for delays by a factor of N. We examine the insertion loss for both λ-scheduler implementations and discuss the trade-offs between the reduction in overall component count and the improvement in the signal characteristics     

Optical performance monitoring in reconfigurable WDM opticalnetworks using subcarrier multiplexing

Optical performance monitoring (OPM) is an important approach to determine the quality of optical channels within an optical core network without passing data through optoelectronic regeneration at the monitor points. Using this approach, the quality or “health” of signals can be determined at arbitrary points in a network without knowledge of the transport history of the data or the details of the transmission path. We report experimental results on the use of subcarrier multiplexing (SCM) to perform a variety of monitoring functions including chromatic dispersion monitoring, wavelength registration, power monitoring, and signal-to-noise ratio (SNR) monitoring     

Model dependency of multivariate autoregressive spectral analysis

A combination of simulations and experimental data analysis has been used to demonstrate that, because cardiovascular control represents a complex linking of input and output parameters, interpreting the variability of individual parameters such as heart rate and arterial pressure virtually requires the use of techniques that quantify control by relating these inputs and outputs. Transfer functions represent appropriate techniques for this purpose. Further, despite the complexities of in vivo physiological control, many of the control elements can be well characterized by only taking into account single inputs and outputs and using a bivariate AR model. However, occasionally when two control systems have a strong and simultaneous influence on a single output parameter, such as arterial pressure and respiratory activity on RR interval, an expansion of the model to the general multivariate case may be required for a complete interpretation. Finally, although not fully demonstrated here, because of the closed-loop nature of cardiovascular control it is likely that algorithms that include causality to account for this characteristic, such as the AR formulation, will most accurately identify the transfer relations     

Psychodynamic formulation, consensual response method, and interpersonal problems.

We describe a new method for aggregating psychodynamic formulations of independent clinicians. 15 patients (10 female and 5 male, aged 23–41) were interviewed before they began brief dynamic psychotherapy. Different panels of 8 formulators (drawn from a pool of 72 psychodynamic clinicians with 10–38 years of clinical experience) observed each videotaped interview and wrote individual formulations. The text of each formulation was divided into thought-units, and thought-units that occurred 3 or more times were combined into a final consensual formulation. (One case was formulated twice to demonstrate the replicability of the method). Other clinical raters then read each consensual formulation and judged, for a list of interpersonal problems, whether each problem was apt to be distressing for that patient. The raters were very successful in predicting which problems were later discussed in treatment. Predictions were best for formulations with a high proportion of interpersonal content. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Review of Making contact: Uses of language in psychotherapy.

Reviews the book, Making contact: Uses of language in psychotherapy by Leston Havens (see record 1986-97288-000). Drawing on ideas from psychoanalytic, existential, and interpersonal theories, the author has provided a thought-provoking and practical book about how to reach, affect, and influence the distant or absent patient through language. This book is not only thought-provoking and practical but also a pleasure to read; Havens possesses a graceful literary style that is vivid, witty, and filled with fresh metaphors. Havens avoids traditional terminology for describing the more disturbed patient in favor of a personal and less objectifying way of speaking. Havens has provided a framework for conceptualizing how language can be used in a disciplined and powerful way to locate the lost selves of our patients. By calling attention to how we speak, he reminds us that language, used empathically and authentically, is the most powerful tool we have to bridge the often wide chasm between us and our patients. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Variable Length Optical Packet Synchronizer

Synchronization of asynchronously arriving variable length Internet Protocol packets to a local clock is demonstrated using a fiber-based optical synchronizer. The synchronizer is a four-stage feed-forward design with a resolution of 853 ps and a dynamic tuning range of 12.8 ns. The arrival time of packets is determined on a per packet basis using a payload envelope detection technique. The synchronizer state is dynamically configured on a per packet basis determined from the arrival time. Layer-1 (bit-error-rate) measurements are presented with power penalties 0.5 dB and an input power dynamic range 15 dB. Layer-2 (packet recovery) measurements are presented with power penalties 1.5 dB.