Failures of retrieval and comparison constrain change detection in natural scenes.

In a change detection paradigm, a target object in a natural scene either rotated in depth, was replaced by another object token, or remained the same. Change detection performance was reliably higher when a target postcue allowed participants to restrict retrieval and comparison processes to the target object (Experiment 1). Change detection performance remained excellent when the target object was not attended at change (Experiment 2) and when a concurrent verbal working memory load minimized the possibility of verbal encoding. (Experiment 3). Together, these data demonstrate that visual representations accumulate in memory from attended objects as the eyes and attention are oriented within a scene and that change blindness derives, at least in part, from retrieval and comparison failure. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of environmental context in mapping invasive plants with hyperspectral image data

Lepidium latifolium (perennial pepperweed) is a noxious Eurasian weed invading riparian and wetland areas of the western US. Effective management of Lepidium requires detailed, accurate maps of its distribution, as may be provided by remote sensing, to contain existing infestations and eradicate incipient populations. We mapped Lepidium with 3 m spatial resolution, 128-band HyMap image data in three sites of California's San Francisco Bay/Sacramento–San Joaquin Delta Estuary (Rush Ranch in Suisun Marsh and the Greater Jepson Prairie Ecosystem and the Cosumnes River Preserve in the Delta). These sites are markedly different in terms of hydrology, salinity, species composition, and structural and landscape diversity. Aggregated classification and regression tree models (CART), incorporating the results of mixture tuned matched filter (MTMF) analyses and spectral physiological indexes, were used to map Lepidium at the three sites. This approach was sufficiently flexible and robust to detect Lepidium with similar accuracies (~ 90%) at both Rush Ranch and Jepson Prairie, but was unsuccessful at Cosumnes River Preserve. Comparisons of the behavior of the MTMFs and the CARTs between sites reveal the importance of environmental context in species mapping. Rush Ranch presents the simplest conditions for mapping Lepidium: it is the wettest and least diverse site and Lepidium is spectrally distinct from co-occurring species. At Jepson Prairie, several co-occurring species closely resemble Lepidium spectrally. Nevertheless, hyperspectral data provide sufficient spectral detail to resolve Lepidium even at this challenging site, which is facilitated by phenological separation from the matrix of annual grasses. At Cosumnes River Preserve, however, Lepidium is neither spectrally nor phenologically distinct, and consequently could not be mapped successfully. Evidence suggests that the success of a remote sensing analysis declines as site complexity increases (species, structural, and landscape diversity; spectral variability; etc.), although this relationship is complex, indirect, and may be phenology-dependent.     

Alu and L1 sequence distributions in Xq24-q28 and their comparative utility in YAC contig assembly and verification

The contents of Alu- and L1-containing TaqI restriction fragments were assessed by Southern blot analyses across YAC contigs already assembled by other means and localized within Xq24-q28. Fingerprinting patterns of YACs in contigs were concordant, and using software based on that of M. V. Olson et al. (1986, Proc. Natl. Acad. Sci. USA 83: 7826) to analyze digitized data on fragment sizes, fingerprinting itself could establish matches among about 40% of a test group of 435 YACs. At 100-kb resolution, both repetitive elements were found throughout the region, with no apparent enrichment of Alu or L1 in DNA of G compared to that found in R bands. However, consistent with a random overall distribution, delimited regions of up to 100 kb contained clusters of repetitive elements. The local concentrations may help to account for the reported differential hybridization of Alu and L1 probes to segments of metaphase chromosomes.     

Representation and selection of relative position.

Part 1 concerns representation: Pop-out for a target that can be distinguished from the distractors only by the relative position of its components was demonstrated, thereby showing that simple shape information is represented preattentively. Findings are discussed in terms of early- vs late-selection debate and in terms of theories of search and texture segregation. Part 2 concerns selection: Strong learning in a varied-mapping paradigm was demonstrated, and it was shown that preattentive shape information can be used for selection. Finally, an account of the learning, namely the group scale hypothesis, is suggested and a final experiment to test it is presented. Results confirm and extend the emphasis placed by J. Duncan and G. W. Humphreys's (1989) attentional engagement theory on grouping processes in visual search. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Benzylation of thiophene using zinc and iron chloride modified montmorillinite clay

Montmorillinite clays, modified with either Zn(II) or Fe(III) chlorides have been used to catalyze the Friedel-Crafts alkylation of thiophene. High yields (ca. 80%) of 2- and 3-benzylthiophene mixtures were obtained using either catalyst in chlorobenzene or nitrobenzene solvent at 80°C. The ratio of 2–3-products was found to be controlled by their relative stability. Reactions were most rapid in nitrobenzene solution (<5 min) and resulted in formation of the 2-isomer as the only mono-substituted product. This is believed to be the first example in which an alkylation of thiophene has been limited to one regio-isomer.     

Post-traumatic stress disorder and smoking: a systematic review.

We conducted a systematic review of what is known about the relationship between post-traumatic stress disorder (PTSD) and smoking to guide research on underlying mechanisms and to facilitate the development of evidence-based tobacco treatments for this population of smokers. We searched Medline, PsychINFO, and the Cochrane Central Register of Controlled Trials and identified 45 studies for review that presented primary data on PTSD and smoking. Smoking rates were high among clinical samples with PTSD (40%-86%) as well as nonclinical populations with PTSD (34%-61%). Most studies showed a positive relationship between PTSD and smoking and nicotine dependence, with odds ratios ranging between 2.04 and 4.52. Findings also suggest that PTSD, rather than trauma exposure itself, is more influential for increasing risk of smoking. A small but growing literature has examined psychological factors related to smoking initiation and maintenance and the overlapping neurobiology of PTSD and nicotine dependence. Observational studies indicate that smokers with PTSD have lower quit rates than do smokers without PTSD. Yet a few tobacco cessation treatment trials in smokers with PTSD have achieved quit rates comparable with controlled trials of smokers without mental disorders. In conclusion, the evidence points to a causal relationship between PTSD and smoking that may be bidirectional. Specific PTSD symptoms may contribute to smoking and disrupt cessation attempts. Intervention studies that test behavioral and pharmacological interventions designed specifically for use in patients with PTSD are needed to reduce morbidity and mortality in this population.     

Efficient Reflectance and Visibility Approximations for Environment Map Rendering

We present a technique for approximating isotropic BRDFs and precomputed self-occlusion that enables accurate and efficient prefiltered environment map rendering. Our approach uses a nonlinear approximation of the BRDF as a weighted sum of isotropic Gaussian functions. Our representation requires a minimal amount of storage, can accurately represent BRDFs of arbitrary sharpness, and is above all, efficient to render. We precompute visibility due to self-occlusion and store a low-frequency approximation suitable for glossy reflections. We demonstrate our method by fitting our representation to measured BRDF data, yielding high visual quality at real-time frame rates.     

Analysis and comparison of real-time sine-wave generation for PWMcircuits

Four methods for hardware and software generation in real time of sine waves suitable for PWM circuits are presented. The sine waves are derived from a truncated modified cosine Taylor series, wt(π-wt) function, a digitally filtered trapezoid, and a second-order differential equation. Triplen injection is incorporated by the addition of a defined magnitude triangular waveform of three times the fundamental frequency. Each sine wave generating technique is implemented, as applicable, in a programmable logic cell array and/or in microprocessor-based software. In each case, the output spectra and total harmonic distortion are compared with computer-simulated results     

Top management support of R&D projects: a strategic leadershipperspective

A study of top management support of 213 R&D projects in 21 major firms revealed significant relationships between independent informants' perceptions of top management support, project characteristics, and project performance. Testing a model based on a strategic leadership perspective, top management support was found to be directed at certain types of projects, i.e., those that were expected to make greater contributions to business goals, represented larger investments, were seeking new products and process versus incremental improvements, and had originated from business sources as opposed to R&D. In addition, even after controlling for these project characteristics, projects with top management support were less likely to be terminated. In contrast, after controlling for project characteristics, completed projects with top management support were not judged to make greater contributions to the firm's business goals suggesting top management may not be able to pick winners. Findings are discussed in terms of future research and implications for top management leadership within R&D