An automated calibration method for non-see-through head mounted displays

Accurate calibration of a head mounted display (HMD) is essential both for research on the visual system and for realistic interaction with virtual objects. Yet, existing calibration methods are time consuming and depend on human judgements, making them error prone, and are often limited to optical see-through HMDs. Building on our existing approach to HMD calibration Gilson et al. (2008), we show here how it is possible to calibrate a non-see-through HMD. A camera is placed inside a HMD displaying an image of a regular grid, which is captured by the camera. The HMD is then removed and the camera, which remains fixed in position, is used to capture images of a tracked calibration object in multiple positions. The centroids of the markers on the calibration object are recovered and their locations re-expressed in relation to the HMD grid. This allows established camera calibration techniques to be used to recover estimates of the HMD display's intrinsic parameters (width, height, focal length) and extrinsic parameters (optic centre and orientation of the principal ray). We calibrated a HMD in this manner and report the magnitude of the errors between real image features and reprojected features. Our calibration method produces low reprojection errors without the need for error-prone human judgements

Carte-de-visite photograph: 2 headed girl, MIllie Crissie, no date.

Conjoined twins Millie and Christine McKoy in full portrait. Date of photograph unknown (likely ca. 1870, subjects died 1912).https://digitalcommons.wofford.edu/littlejohnmss/1306/thumbnail.jp

The neural underpinnings of vicarious experience

Everyday we vicariously experience a range of states that we observe in other people: we may "feel" embarrassed when witnessing another making a social faux pas, or we may feel sadness when we see a loved one upset. In some cases this process appears to be implicit. For instance, observing pain in others may activate pain-related neural processes but without generating an overt feeling of pain. In other cases, people report a more literal, conscious sharing of affective or somatic states and this has sometimes been described as representing an extreme form of empathy. By contrast, there appear to be some people who are limited in their ability to vicariously experience the states of others. This may be the case in several psychiatric, neurodevelopmental, and personality disorders where deficits in interpersonal understanding are observed, such as schizophrenia, autism, and psychopathy. In recent decades, neuroscientists have paid significant attention to the understanding of the “social brain,” and the way in which neural processes govern our understanding of other people. In this Research Topic, we wish to contribute towards this understanding and ask for the submission of manuscripts focusing broadly on the neural underpinnings of vicarious experience. This may include theoretical discussion, case studies, and empirical investigation using behavioural techniques, electrophysiology, brain stimulation, and neuroimaging in both healthy and clinical populations. Of specific interest will be the neural correlates of individual differences in traits such as empathy, how we distinguish between ourselves and other people, and the sensorimotor resonant mechanisms that may allow us to put ourselves in another's shoes

Methane emissions inventory verification in southern California

Methane (CH4) and carbon monoxide (CO) mixing ratios were measured at an air quality monitoring station near the Mt. Wilson (MW) Observatory in southern California starting in the spring of 2007. Diurnal variation and mixing ratio correlation (R2 = 0.81) were observed. The correlation results observed agree with previous aircraft measurements collected over the greater Los Angeles (LA) metropolitan area. The consistent agreement between CH4 and CO indicates these gases are well-mixed before reaching the sampling site and the emission source contributions of both compounds are reasonably constant. Since CH4 and CO are considered non-reactive on the time scale of dispersion within the LA urban area and their emission sources are likely to be similarly distributed (e.g., associated with human activities) they are subject to similar scales of atmospheric transport and dilution. This behavior allows the relationship of CH4 and CO to be applied for estimation of CH4 emissions using well-documented CO emissions. Applying this relationship a "top-down" CH4 inventory was calculated for LA County based on the measurements observed at MW and compared with the California Air Resources Board (CARB) "bottom-up" CH4 emissions inventory based on the Intergovernmental Panel on Climate Change recommended methodologies. The "top-down" CH4 emissions inventory is approximately one-third greater than CARB's "bottom-up" inventory for LA County. Considering the uncertainties in both methodologies, the different CH4 emissions inventory approaches are in good agreement, although some under and/or uninventoried CH4 sources may exist

The energetic consequence of specific dynamic action in southern bluefin tuna Thunnus maccoyii

Copyright © 2007 The Company of BiologistsThe effect of feeding on the rate of oxygen consumption (O2) of four groups of three southern bluefin tuna Thunnus maccoyii (SBT) was examined in a large static respirometer at water temperatures of 18.2-20.3°C. Six feeding events of rations between 2.1-8.5% body mass (%Mb) of Australian sardines (Sardinops neopilchardus) were recorded (two of the groups were fed twice). Before feeding, fish swam between 0.71 and 1.4 body lengths s-1 (BL s-1) and the routine metabolic rate (RMR) was 366±32.5 mg kg-1 h-1 (mean ± s.e.m.). For all trials, O2 was elevated post feeding, presumably as a result of specific dynamic action (SDA). Swimming velocity was also elevated post feeding for periods similar to that of O2 (between 20-45 h, longest for the largest rations). Post feeding swimming velocity increased to between 0.87-2.6 BL s-1 and was also dependent on ration consumed. It is suggested that the purpose of increased post-feeding swimming velocity was to increase ventilation volume as a response to the enhanced metabolic demand associated with SDA. Peak post-prandial O2 increased linearly with ration size to a maximum of 1290 mg kg-1 h-1, corresponding to 2.8 times the RMR. When converted to its energy equivalent, total magnitude of SDA was linearly correlated with ration size to a maximum of 192 kJ kg-1 h-1, and as a proportion of gross energy ingested (SDA coefficient), it averaged 35±2.2%. These results demonstrate that, although the factorial increase of SDA in SBT is similar to that of other fish species, the absolute energetic cost of SDA is much higher. These results support the contention that tuna are energy speculators, gambling high rates of energy expenditure for potentially higher rates of energy returns. The ration that southern bluefin tuna require to equal the combined metabolic costs of SDA and RMR is estimated in this study to be 3.5%Mb of Australian sardines per day.Q. P. Fitzgibbon, R. S. Seymour, D. Ellis and J. Buchana

Comparative Effectiveness of Endovascular vs Surgical Arteriovenous Fistulas: A Preliminary Analysis

Purpose: The objective of this study was to compare the efficacy and safety of endovascular arteriovenous fistula (endoAVF) creation versus open surgical AVF (openAVF) for hemodialysis access across centers participating in the Dialysis Access Learning and Innovation Collaborative (DiAL-In Collaborative) in the United States. In this preliminary analysis, we report the baseline characteristics and clinical profile of patients enrolled at a single center. Materials and Methods: A retrospective cohort study was conducted in chronic kidney disease patients who underwent creation of an upper arm autogenous vascular access for hemodialysis (2018-2022) at the Brigham and Women’s Hospital in Boston, MA. Data were gathered from the Vascular Quality Initiative dataset and supplemented with chart adjudication. All patients were followed for a minimum of one year with a maximum follow-up until July 2023. Results: A total of 145 patients were enrolled (13 endoAVF and 132 openAVF). Overall, 67% of patients were hemodialysis dependent and 2% were peritoneal dialysis dependent at the time of fistula creation. Patients with an endoAVF were older (75 vs. 67 years; p= 0.073), and more likely to be male (62% vs. 48%; p= 0.047 ). The openAVF cohort had a higher proportion of patients with medical comorbidities such as congestive heart failure (44% vs. 31%; p= 0.057), history of percutaneous coronary intervention (19% vs. 8%; p= 0.022), and diabetes (58% vs. 46%; p=.089). Conclusions: In this single-center preliminary analysis, we found differences in the baseline demographic and clinical profile of patients undergoing endoAVF and openAVF for hemodialysis. A thoughtful analytical approach will need to be employed to account for these important baseline differences to compare outcomes of endoAVF versus openAVF in the multicenter DiAL-In Collaborative

Detection of elliptical shapes via cross-entropy clustering

The problem of finding elliptical shapes in an image will be considered. We discuss the solution which uses cross-entropy clustering. The proposed method allows the search for ellipses with predefined sizes and position in the space. Moreover, it works well for search of ellipsoids in higher dimensions