High-speed fiber-optic links for distribution of satellite traffic

Low-loss fiber-optic links are designed for distribution of data and the frequency reference in large-aperture phased-array antennas based on the transmit/receive-level data mixing architecture. In particular, design aspects of a fiber-optic link satisfying the distribution requirements of satellite data traffic are presented. The design is addressed in terms of reactively matched optical transmitter and receiver modules. Analog and digital characterization of a 50-m fiber-optic link realized using these modules indicates the applicability of this architecture as the only viable alternative for distribution of data signals inside a satellite at present. It is demonstrated that the design of a reactive matching modules enhances the link performance. A dynamic range of 88 dB/MHz was measured for analog data over 500-1000-MHz bandwidth     

High gain, wide dynamic range L-band externally modulated fibre optic link

An L-band externally modulated fibre-optic datalink consisting of a semiconductor laser source, a LiNbO/sub 3/ E-O modulator, and an InGaAs detector with lossless impedance matching networks is operated at 900 MHz with 6.4 dB gain and a dynamic range of 70 dB MHz/sup 2/3/ over a 3 dB bandwidth of 50 MHz.<>     

Preparation and luminescence of Pb2OFX; X=Cl,Br, I

The title compounds were prepared and crystallized with the ideal Perite structure. Low temperature luminescence spectra are presented.     

Trade-off studies of a hyperspectral infrared sounder on a geostationary satellite

Trade-off studies on spectral coverage, signal-to-noise ratio (SNR), and spectral resolution for a hyperspectral infrared (IR) sounder on a geostationary satellite are summarized. The data density method is applied for the vertical resolution analysis, and the rms error between true and retrieved profiles is used to represent the retrieval accuracy. The effects of spectral coverage, SNR, and spectral resolution on vertical resolution and retrieval accuracy are investigated. The advantages of IR and microwave sounder synergy are also demonstrated. When focusing on instrument performance and data processing, the results from this study show that the preferred spectral coverage combines long-wave infrared (LWIR) with the shorter middle-wave IR (SMidW). Using the appropriate spectral coverage, a hyperspectral IR sounder with appropriate SNR can achieve the required science performance (1 km vertical resolution, 1 K temperature, and 10% relative humidity retrieval accuracy). The synergy of microwave and IR sounders can improve the vertical resolution and retrieval accuracy compared to either instrument alone.     

Exploiting bias in a non-immune human antibody library to predict antigenicity

Non-immune human antibody fragment libraries have generated antigen-binding proteins useful as prospective research, imaging, diagnostic and therapeutic agents. However, because the generation of such libraries relies on cloning antibody sequences from the circulating immune repertoire rather than truly na?ve, germline sequences, their composition may reflect the deletion of autoreactive sequences, making them less suited for isolating binding clones to human antigens, but perhaps useful in applications where an in vitro handle on representative circulating antibody diversity is desired. Here we demonstrate that a large non-immune human scFv library is relatively depleted of sequences capable of recognizing human antigens as compared with orthologs antigens. Additionally, because this non-na?ve, non-immune library may capture a representative section of antibody diversity, we explore its possible utility in conducting early pre-screens to predict the antigenicity of prospective therapeutics and find a correlation between the clinical immunogenicity of a small panel of protein therapeutics with their propensity for interacting with the library.     

Mercury exposure may suppress baseline corticosterone levels in juvenile birds

Mercury exposure has been associated with a wide variety of negative reproductive responses in birds, however few studies have examined the potential for chick impairment via the hypothalamic-pituitary-adrenal (HPA) axis. The HPA axis regulates corticosterone levels during periods of stress. We examined the relationship between baseline fecal corticosterone metabolite concentrations and mercury concentrations in down feathers of recently hatched (<3 days) and blood of older (15-37 days) Forster's tern (Sterna forsteri) chicks in San Francisco Bay, California. Baseline fecal corticosterone metabolite concentrations were negatively correlated with mercury concentrations in blood of older chicks (decreasing by 81% across the range of observed mercury concentrations) while accounting for positive correlations between corticosterone concentrations and number of fledgling chicks within the colony and chick age. In recently hatched chicks, baseline fecal corticosterone metabolite concentrations were weakly negatively correlated with mercury concentrations in down feathers (decreasing by 45% across the range of observed mercury concentrations) while accounting for stronger positive correlations between corticosterone concentrations and colony nest abundance and date. These results indicate that chronic mercury exposure may suppress baseline corticosterone concentrations in tern chicks and suggests that a juvenile bird's ability to respond to stress may be reduced via the downregulation of the HPA axis.     

The Visible Human<Superscript>®</Superscript> at the University of Colorado 15 years later

The Visible Human has come through ages, providing a foundation of photorealistic anatomy for learner-centered, interactive education. Pathways for improvement of the Visible Human process for reverse engineering the macrostructure of the human body have been developed to provide higher resolution and decreased production time for segmentation and modeling human form. The assignment of physical properties, the development of algorithms for the interaction of surgical tools with this virtual anatomy and the availability of high-fidelity haptic interfaces provide the basis for fully immersive surgical training and certification in an environment that is zero direct-risk to patients. Interactive journal publishing, 3D stereoscopic anatomical visualization software and surgical simulators, all based on the Visible Human, the history of the Project and its utilization and provide a framework for its evolution and role in delivering education, training, certification and credentialing through virtual reality to the health care workforce of tomorrow.

Working Memory and Intelligence: Different Constructs. Reply to Oberauer et al. (2005) and Kane et al. (2005).

The authors address agreements and disagreements with the M. J. Kane, D. Z. Hambrick, and A. R. A. Conway (2005; see record 2004-22408-004) and K. Oberauer, R. Schulze, O. Wilhelm, and H.-M. Sü? (2005; see record 2004-22408-003) commentaries on P. L. Ackerman, M. E. Beier, and M. O. Boyle (2005; see record 2004-22408-002). They discuss the following issues: (a) the relationship between working memory (WM) and general intelligence (g), (b) the reanalyses included in the comments, (c) the use of a fixed-effects model versus a random-effects model for the meta-analysis, (d) the use of structural equation modeling analyses and structural coefficients as equivocal evidence for the relationship between WM and intelligence, and (e) the problem of confirmation bias in research on WM. Although the authors disagree with their commentators about the magnitude of the relationship between WM and g, in the final analysis it appears that all concerned parties agree that WM and intelligence are different constructs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working Memory and Intelligence: The Same or Different Constructs?

Several investigators have claimed over the past decade that working memory (WM) and general intelligence (g) are identical, or nearly identical, constructs, from an individual-differences perspective. Although memory measures are commonly included in intelligence tests, and memory abilities are included in theories of intelligence, the identity between WM and intelligence has not been evaluated comprehensively. The authors conducted a meta-analysis of 86 samples that relate WM to intelligence. The average correlation between true-score estimates of WM and g is substantially less than unity (p? = .479). The authors also focus on the distinction between short-term memory and WM with respect to intelligence with a supplemental meta-analysis. The authors discuss how consideration of psychometric and theoretical perspectives better informs the discussion of WM-intelligence relations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

When recognition memory fails: The use of an elimination strategy by young children.

Two experiments explored the response strategies of young children in the case of the evident failure of recognition memory. 20 4-yr-olds and 20 7-yr-olds were shown a series of pictorial paired associates. At test, Ss had to choose from a set of 4 items the response that had been paired with a particular stimulus during study. The response set consisted of 3 response items paired with a stimulus during study, and 1 new item. In addition to testing the pairs seen during study, 4 new stimulus–response pairs were tested in the same manner. Response choices for these new stimuli, as well as for the stimuli seen during study, allowed an assessment of the strategies used by Ss in the situation where recognition memory has apparently failed. Results show that Ss of both ages employed a reasoning-by-exclusion elimination strategy in responding to the stimuli. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)