The Orbit and Occultations of KH 15D

The unusual flux variations of the pre-main-sequence binary star KH 15D have been attributed to occultations by a circumbinary disk. We test whether or not this theory is compatible with newly available data, including recent radial velocity measurements, CCD photometry over the past decade, and photographic photometry over the past 50 years. We find the model to be successful, after two refinements: a more realistic motion of the occulting feature, and a halo around each star that probably represents scattering by the disk. The occulting feature is exceptionally sharp-edged, raising the possibility that the dust in the disk has settled into a thin layer, and providing a tool for fine-scale mapping of the immediate environment of a T Tauri star. However, the window of opportunity is closing, as the currently visible star may be hidden at all orbital phases by as early as 2008.Comment: To appear in ApJ [16 pages, 13 figures

Did You See That? A Study of Change Blindness

OBJECTIVES Increasing concern has been expressed regarding the safety implications of drivers attempting to use in-vehicle devices other than cellular phones while driving. To address this issue, the effect of cognitive load on visual attention merits investigation. Strayer and Johnston (2001) found invehicle system use, specifically cell-phone use, disrupts performance by diverting attention to an engaging cognitive context other than the one immediately associated with driving. Recarte and Nunes (2000) demonstrated that scanning patterns and visual attention can be disrupted by cognitive load. In-vehicle systems can increase the cognitive load of the driver, making it more difficult for the driver to direct attention to the visual scene. The change blindness phenomenon may be useful way to investigate how cognitive load affects attention. Change blindness is the inability to detect scene change when the change occurs in conjunction with an action such as a blink (O’Regan, Deubel, Clark, and Rensink, 2000), eye movement (Wallis and Bulthoff, 2000), or an image that masks the onset of the change (Simons and Levin, 1998). The aim of this experiment was to study the effect of cognitive loading on individuals’ ability to detect change in their visual environment using a speech-based email task. METHODS Twenty participants completed a series of five conditions. In two of these conditions the participants did just one task: either the e-mail task or the visual search task. In the other three conditions participants completed the e-mail and the visual search tasks concurrently. In one email task condition the speech recognition system worked perfectly. In a second condition, speech recognition errors caused the wrong menu item to be selected. In a third condition, speech recognition errors caused the user to be displaced to the wrong menu. In three of the visual search task conditions participants were asked to identify changes that occurred in visual scenes, using the Rensink, et al. (1997) flicker paradigm while navigating a speech-based e-mail system. The visual task presented a series of four displays. These were: an unaltered image (300ms), a gray screen (1150ms), a second image (300ms), and a gray screen (1150ms). The second image was either the unaltered image or an image altered by the addition or removal of an element. The remaining conditions for both the e-mail task and visual search task were labeled as baseline. The baseline measurements were used to evaluate the effects of cognitive load on detection of scene changes. RESULTS Analyses showed that detection of scene changes took significantly longer when participants were cognitively loaded with the e-mail task (mean 5.05) compared to when they were not (mean 4.35), F(3,67)=11.13, p< 0.0001. Analyses also showed participants took significantly longer to determine that the scene had not changed (mean 5.99) than to detect a change had occurred (mean 3.72), F(2,67)=271.95, p <0.0001. Scene detection accuracy was significantly reduced when participants were cognitively loaded with the e-mail task, F(3,67)=5.47, p0.0010. Speech recognition errors introduced by the researcher had little effect on times to determine scene changes as well as time to detect meaningful and non-meaningful scene changes. CONCLUSION The results of this study demonstrate that change detection is sensitive to cognitive load and that endogenous control of visual attention may have been affected by the introduction of the e-mail system. It also shows that the paradigm of scenes with and without changes seems to be a promising and sensitive tool for measuring the effects of cognitive load on an individual’s ability to detect change. REFERENCES O\u27Regan, J.K., H. Deubel, J.J. Clark, & R.A. Rensink. (2000). Picture changes during blinks: Looking without seeing and seeing without looking. Visual Cognition 7(1-3), 191-211. Recarte, M.A. & Nunes, L.M. (2000). Effects of verbal and spatial imagery tasks to eye fixations while driving. Journal of Experimental Psychology: Applied,6, 31-43 Rensink, R.A., Oregan, J.K., & Clark, J.J. (1997). To see or not see: The need for attention to perceive changes in scenes. Psychological Sciences, 8, 368-373 Simons, D.J. and D.T. Levin. (1998). Failure to detect changes to people during a real-world interaction. Psychonomic Bulletin & Review 5(4), 644-649. Strayer, D.L. & Johnston, W.A. (2001). Driven to distraction: Dual-task studies of simulated driving and conversing on a cellular phone. Psychological Science, 12, 462-466 Wallis, G. and H. Bulthoff. (2000). What’s scene and not seen: Influences of movement and task upon what we see. Visual Cognition 7(1-3), 175-190

Sorting Guilty Minds

Because punishable guilt requires that bad thoughts accompany bad acts, the Model Penal Code (MPC) typically requires that jurors infer the past mental state of a criminal defendant. More specifically, jurors must sort that mental state into one of four specific categories - purposeful, knowing, reckless, or negligent - which in turn defines the nature of the crime and the extent of the punishment. The MPC therefore assumes that ordinary people naturally sort mental states into these four categories with a high degree of accuracy, or at least can reliably do so when properly instructed. It also assumes that ordinary people will order these categories of mental state, by increasing amount of punishment, in the same severity hierarchy that the MPC prescribes. The MPC, now turning 50 years old, has previously escaped the scrutiny of comprehensive empirical research on these assumptions underlying its culpability architecture. Our new empirical studies, reported here, find that most of the mens rea assumptions embedded in the MPC are reasonably accurate as a behavioral matter. Even without the aid of the MPC definitions, subjects were able to regularly and accurately distinguish among purposeful, negligent, and blameless conduct. Nevertheless, our subjects failed to distinguish reliably between knowing and reckless conduct. This failure can have significant sentencing consequences in some types of crimes, especially homicide

Surgical Delay of the Thoracodorsal Artery Perforator Flap for Autologous Breast Reconstruction

Background: When women are poor candidates for abdomen-based free flap reconstruction, the muscle-sparing thoracodorsal artery perforator (TDAP) flap may be considered for total autologous breast reconstruction due to its reliable perforator anatomy and function as a pedicled flap, requiring no vascular anastomosis. However, the TDAP flap is not as popular as other autologous breast reconstruction methods since it is often limited by flap size and distal tip necrosis. Objective: We aim to demonstrate a novel use of the delay phenomenon in TDAP flaps for total autologous breast reconstruction. Methods: This prospective IRB-approved study recruited patients between April 2021 and August 2022 for autologous breast reconstruction using surgically delayed TDAP flap reconstruction when abdomen-based flap reconstruction was contraindicated. This involved two operations: 1) dissection of the TDAP flap except for a distal skin bridge, then 2) reconstruction of the breast. Doppler ultrasound was used to locate flap perforators and assess pre- and postsurgical delay caliber (mm) and flow (cm/s). Data collected included flap dimensions (cm x cm), operative time (min), delay between dissection and reconstruction (days), hospital length of stay (days), complications/revisions, and follow-up (days). Results: Five (5) patients and seven (7) flaps were included in this study to date. Median age and BMI of patients was 59.8 years old and 30.7 kg/m2 , respectively (n=6 operations). Average flap skin paddle dimension was 33.3 x 11.0 cm (n=3 flaps). Median time between surgical delay and inset was 6 days, ranging 2-7 days (n=7 flaps). The surgically delayed TDAP arterial caliber increased from 1.3 ± 0.385 mm pre-delay to 1.9 ± 0.350 mm post-delay (n=3 flaps, 95% CI, *

Control of magnetic anisotropy by orbital hybridization in (La0.67Sr0.33MnO3)n/(SrTiO3)n superlattice

The asymmetry of chemical nature at the hetero-structural interface offers an unique opportunity to design desirable electronic structure by controlling charge transfer and orbital hybridization across the interface. However, the control of hetero-interface remains a daunting task. Here, we report the modulation of interfacial coupling of (La0.67Sr0.33MnO3)n/(SrTiO3)n superlattices by manipulating the periodic thickness with n unit cells of SrTiO3 and n unit cells La0.67Sr0.33MnO3. The easy axis of magnetic anisotropy rotates from in-plane (n = 10) to out-of-plane (n = 2) orientation at 150 K. Transmission electron microscopy reveals enlarged tetragonal ratio > 1 with breaking of volume conservation around the (La0.67Sr0.33MnO3)n/(SrTiO3)n interface, and electronic charge transfer from Mn to Ti 3d orbitals across the interface. Orbital hybridization accompanying the charge transfer results in preferred occupancy of 3d3z2-r2 orbital at the interface, which induces a stronger electronic hopping integral along the out-of-plane direction and corresponding out-of-plane magnetic easy axis for n = 2. We demonstrate that interfacial orbital hybridization in superlattices of strongly correlated oxides may be a promising approach to tailor electronic and magnetic properties in device applications

Hundreds of variants clustered in genomic loci and biological pathways affect human height

Most common human traits and diseases have a polygenic pattern of inheritance: DNA sequence variants at many genetic loci influence the phenotype. Genome-wide association (GWA) studies have identified more than 600 variants associated with human traits, but these typically explain small fractions of phenotypic variation, raising questions about the use of further studies. Here, using 183,727 individuals, we show that hundreds of genetic variants, in at least 180 loci, influence adult height, a highly heritable and classic polygenic trait. The large number of loci reveals patterns with important implications for genetic studies of common human diseases and traits. First, the 180 loci are not random, but instead are enriched for genes that are connected in biological pathways (P = 0.016) and that underlie skeletal growth defects (P < 0.001). Second, the likely causal gene is often located near the most strongly associated variant: in 13 of 21 loci containing a known skeletal growth gene, that gene was closest to the associated variant. Third, at least 19 loci have multiple independently associated variants, suggesting that allelic heterogeneity is a frequent feature of polygenic traits, that comprehensive explorations of already-discovered loci should discover additional variants and that an appreciable fraction of associated loci may have been identified. Fourth, associated variants are enriched for likely functional effects on genes, being over-represented among variants that alter amino-acid structure of proteins and expression levels of nearby genes. Our data explain approximately 10% of the phenotypic variation in height, and we estimate that unidentified common variants of similar effect sizes would increase this figure to approximately 16% of phenotypic variation (approximately 20% of heritable variation). Although additional approaches are needed to dissect the genetic architecture of polygenic human traits fully, our findings indicate that GWA studies can identify large numbers of loci that implicate biologically relevant genes and pathways.

Capturing Driver Response to In-Vehicle Human-Machine Interface Technologies Using Facial Thermography

Measuring driver response to in-vehicle human-machine interface (HMI) systems is critical for the automotive design and evaluation process. Physiological measures provide a useful complement to performance-based and subjective measures because they promise an estimate of the affective response of drivers to an in-vehicle system in a way that requires no overt response by the driver. This research explored how facial temperature might reflect the drivers’ response to the demands they confront when interacting with in-vehicle systems. Sixteen drivers completed a series of in-vehicle tasks while driving in a simulator. Facial temperature was measured using an infrared camera. The analyses focus on how the thermal data, aggregated over four facial regions, correlated with both measures of driving performance and subjective ratings of workload and frustration. Facial temperature measures correlated with more driving performance measures of longitudinal control than lateral control, suggesting that thermal measures are sensitive to different cognitive processes than are typically assessed by measures of steering and lane position. Thermal measures aggregated over a 15-second window correlated with subjective ratings. Unlike other measures typically used to evaluate in-vehicle systems that are aggregated over long time windows, thermal measures have temporal specificity and might be able to identify specific interactions that increase workload and frustration. No single facial area or summary measure emerged as the best indicator of driver response; rather, composite measures of facial temperature could be developed that offer a more complete profile of driver response