Perceiving depth and motion in depth from successive occlusion.

Occlusion, or interposition, is one of the strongest and best-known pictorial cues to depth. Furthermore, the successive occlusions of previous objects by newly presented objects produces an impression of increasing depth. Although the perceived motion associated with this illusion has been studied, the depth percept has not. To investigate, participants were presented with two piles of disks with one always static and the other either a static pile or a stacking pile where a new disk was added every 200 ms. We found static piles with equal number of disks appeared equal in height. In contrast, the successive presentation of disks in the stacking condition appeared to enhance the perceived height of the stack-fewer disks were needed to match the static pile. Surprisingly, participants were also more precise when comparing stacking versus static piles of disks. Reversing the stacking by removing rather than adding disks reversed the bias and degraded precision. In follow-up experiments, we used nonoverlapping static and dynamic configurations to show that the effects are not due to simple differences in perceived numerosity. In sum, our results show that successive occlusions generate a greater sense of height than occlusion alone, and we posit that dynamic occlusion may be an underappreciated source of depth information.

Differences in virtual and physical head orientation predict sickness during active head-mounted display-based virtual reality.

During head-mounted display (HMD)-based virtual reality (VR), head movements and motion-to-photon-based display lag generate differences in our virtual and physical head pose (referred to as DVP). We propose that large-amplitude, time-varying patterns of DVP serve as the primary trigger for cybersickness under such conditions. We test this hypothesis by measuring the sickness and estimating the DVP experienced under different levels of experimentally imposed display lag (ranging from 0 to 222 ms on top of the VR system's ~ 4 ms baseline lag). On each trial, seated participants made continuous, oscillatory head rotations in yaw, pitch or roll while viewing a large virtual room with an Oculus Rift CV1 HMD (head movements were timed to a computer-generated metronome set at either 1.0 or 0.5 Hz). After the experiment, their head-tracking data were used to objectively estimate the DVP during each trial. The mean, peak, and standard deviation of these DVP data were then compared to the participant's cybersickness ratings for that trial. Irrespective of the axis, or the speed, of the participant's head movements, the severity of their cybersickness was found to increase with each of these three DVP summary measures. In line with our DVP hypothesis, cybersickness consistently increased with the amplitude and the variability of our participants' DVP. DVP similarly predicted their conscious experiences during HMD VR-such as the strength of their feelings of spatial presence and their perception of the virtual scene's stability.

Effects of Decreased Immunization Coverage for Hepatitis B Virus Caused by COVID-19 in World Health Organization Western Pacific and African Regions, 2020.

The World Health Organization-designated Western Pacific Region (WPR) and African Region (AFR) have the highest number of chronic hepatitis B virus (HBV) infections worldwide. The COVID-19 pandemic has disrupted childhood immunization, threatening progress toward elimination of hepatitis B by 2030. We used a published mathematical model to estimate the number of expected and excess HBV infections and related deaths after 10% and 20% decreases in hepatitis B birth dose or third-dose hepatitis B vaccination coverage of children born in 2020 compared with prepandemic 2019 levels. Decreased vaccination coverage resulted in additional chronic HBV infections that were 36,342-395,594 in the WPR and 9,793-502,047 in the AFR; excess HBV-related deaths were 7,150-80,302 in the WPR and 1,177-67,727 in the AFR. These findings support the urgent need to sustain immunization services, implement catch-up vaccinations, and mitigate disruptions in hepatitis B vaccinations in future birth cohorts.

Shape judgments in natural scenes: Convexity biases versus stereopsis.

Determining the relief of upcoming terrain is critical to locomotion over rough or uneven ground. Given the significant contribution of stereopsis to perceived surface shape, it should play a crucial role in determining the shape of ground surfaces. The aim of this series of experiments was to evaluate the relative contribution of monocular and binocular depth cues to judgments of ground relief. To accomplish this goal, we simulated a depth discrimination task using naturalistic imagery. Stimuli consisted of a stereoscopically rendered grassy terrain with a central mound or a dip with varying height. We measured thresholds for discrimination of the direction of the depth offset. To determine the relationship between relief discrimination and measures of stereopsis, we used two stereoacuity tasks performed under the same viewing conditions. To assess the impact of ambiguous two-dimensional shading cues on depth judgments in our terrain task, we manipulated the intensity of the shading (low and high). Our results show that observers reliably discriminated ground reliefs as small as 20 cm at a viewing distance of 9.1 m. As the shading was intensified, a large proportion of observers (30%) exhibited a strong convexity bias, even when stereopsis indicated a concave depression. This finding suggests that there are significant individual differences in the reliance on assumptions of surface curvature that must be considered in experimental conditions. In impoverished viewing environments with limiting depth cues, these convexity biases could persist in judgments of ground relief, especially when shading cues are highly salient.

Frailty: Evaluation and Management.

Frailty, which is a geriatric syndrome that affects 5% to 17% of older adults, is a state of increased vulnerability across multiple health domains that leads to adverse health outcomes. Frail older adults are at increased risk of falls, disability, hospitalizations, and death. Frailty may initially be overlooked or incorrectly identified as part of the normal aging process because of the variable nature of the presentation and diagnosis. Symptoms include generalized weakness, exhaustion, slow gait, poor balance, decreased physical activity, cognitive impairment, and weight loss. There is no current recommendation for routine screening. A comprehensive geriatric assessment can identify risk factors and symptoms that suggest frailty. Several validated frailty assessment tools can evaluate a patient for frailty. Patients are diagnosed as not-frail, prefrail, or frail. Patients with a larger number of frail attributes are at higher risk of poor outcomes. The management of frail patients must be individualized and tailored to each patient's goals of care and life expectancy. Physical activity and balance exercises may be suitable for patients who are less frail. Palliative care and symptom control may be appropriate for those who are more frail.

Sensors for Fire and Smoke Monitoring.

Mastery of fire is intimately linked to advances in human civilization, culture and technology [...].

Contributions of Stereopsis and Aviation Experience to Simulated Rotary Wing Altitude Estimation.

OBJECTIVE: We examined the contribution of binocular vision and experience to performance on a simulated helicopter flight task. BACKGROUND: Although there is a long history of research on the role of binocular vision and stereopsis in aviation, there is no consensus on its operational relevance. This work addresses this using a naturalistic task in a virtual environment. METHOD: Four high-resolution stereoscopic terrain types were viewed monocularly and binocularly. In separate experiments, we evaluated performance of undergraduate students and military aircrew on a simulated low hover altitude judgment task. Observers were asked to judge the distance between a virtual helicopter skid and the ground plane. RESULTS: Our results show that for both groups, altitude judgments are more accurate in the binocular viewing condition than in the monocular condition. However, in the monocular condition, aircrew were more accurate than undergraduate observers in estimating height of the skid above the ground. CONCLUSION: At simulated altitudes of 5 ft (1.5 m) or less, binocular vision provides a significant advantage for estimation of the depth separation between the landing skid and the ground, regardless of relevant operational experience. However, when binocular cues are unavailable aircrew outperform undergraduate observers, a result that likely reflects the impact of training on the ability to interpret monocular depth cues.

A microarray-based pathogen chip for simultaneous molecular detection of transfusion-transmitted infectious agents.

BACKGROUND: New and emerging transfusion-transmitted infections remain a threat to the blood supply. Blood donors are currently screened for less than half of known agents, primarily by individual tests. A screening platform that could simultaneously detect all known transfusion-transmitted pathogens and allow rapid addition of new targets would significantly increase blood safety and could improve the response to new agents. We describe the early stage development and validation of a microarray-based platform (pathogen chip) for simultaneous molecular detection of transfusion-transmitted RNA viruses. METHODS: Sixteen RNA viruses that pose a significant risk for transfusion-transmission were selected for inclusion on the pathogen chip. Viruses were targeted for detection by 1769 oligonucleotide probes selected by Agilent eArray software. Differentially concentrated positive plasma samples were used to evaluate performance and limits of detection in the context of individual pathogens or combinations to simulate coinfection. RNA-viruses detection and concentration were validated by RT-qPCR. RESULTS: Hepatitis A, B and C, Chikungunya, dengue 1-4, HIV 1-2, HTLV I-II, West Nile and Zika viruses were all correctly identified by the pathogen chip within the range of 105 to 102 copies/mL; hepatitis E virus from 105 to 104. In mixtures of 3-8 different viruses, all were correctly identified between 105 and 103 copies/mL. CONCLUSIONS: This microarray-based multi-pathogen screening platform accurately and reproducibly detected individual and mixed RNA viruses in one test from single samples with limits of detection as low as 102 copies mL.

Binding of Free and Immune Complex-Associated Hepatitis C Virus to Erythrocytes Is Mediated by the Complement System.

Erythrocytes bind circulating immune complexes (ICs) and facilitate IC clearance from the circulation. Chronic hepatitis C virus (HCV) infection is associated with IC-related disorders. In this study, we investigated the kinetics and mechanism of HCV and HCV-IC binding to and dissociation from erythrocytes. Cell culture-produced HCV was mixed with erythrocytes from healthy blood donors, and erythrocyte-associated virus particles were quantified. Purified complement proteins, complement-depleted serum, and complement receptor antibodies were used to investigate complement-mediated HCV-erythrocyte binding. Purified HCV-specific immunoglobulin G (IgG) from a chronic HCV-infected patient was used to study complement-mediated HCV-IC/erythrocyte binding. Binding of HCV to erythrocytes increased 200- to 1,000-fold after adding complement active human serum in the absence of antibody. Opsonization of free HCV occurred within 10 minutes, and peak binding to erythrocytes was observed at 20-30 minutes. Complement protein C1 was required for binding, whereas C2, C3, and C4 significantly enhanced binding. Complement receptor 1 (CR1, CD35) antibodies blocked the binding of HCV to erythrocytes isolated from chronically infected HCV patients and healthy blood donors. HCV-ICs significantly enhanced complement-mediated binding to erythrocytes compared to unbound HCV. Dissociation of complement-opsonized HCV from erythrocytes depended on the presence of Factor I. HCV released by Factor I bound preferentially to CD19+ B cells compared to other leukocytes. Conclusion: These results demonstrate that complement mediates the binding of free and IC-associated HCV to CR1 on erythrocytes and provide a mechanistic rationale for investigating the differential phenotypic expression of HCV-IC-related disease.

Monovision: Consequences for depth perception from large disparities.

Recent studies have confirmed that monovision treatment degrades stereopsis but it is not clear if these effects are limited to fine disparity processing, or how they are affected by viewing distance or age. Given the link between stereopsis and postural stability, it is important that we have full understanding of the impact of monovision on binocular function. In this study we assessed the short-term effects of optically induced monovision on a depth-discrimination task for young and older (presbyopic) adults. In separate sessions, the upper limits of stereopsis were assessed with participants' best optical correction and with monovision (-1D and +1D lenses in front of the dominant and non-dominant eyes respectively), at both near (62 cm) and far (300 cm) viewing distances. Monovision viewing resulted in significant reductions in the upper limit of stereopsis or more generally in discrimination performance at large disparities, in both age groups at a viewing distance of 300 cm. Dynamic photorefraction performed on a sample of four young observers revealed that they tended to accommodate to minimize blur in one eye at the expense of blur in the other. Older participants would have experienced roughly equivalent blur in the two eyes. Despite this difference, both groups displayed similar detrimental effects of monovision. In addition, we find that discrimination accuracy was worse with monovision at the 3 m viewing distance which involves fixation distances that are typical during walking. These data suggest that stability during locomotion may be compromised, a factor that is of concern for our older participants.

Challenges in the Diagnosis of Euglycemic Diabetic Ketoacidosis in a Patient With Multiple Sclerosis Taking a Sodium-Glucose Cotransporter 2 Inhibitor.

BACKGROUND: Sodium-glucose co-transporter 2 (SGLT2) inhibitors have been reported to cause euglycemic diabetic ketoacidosis (eDKA), a diagnosis that may be challenging to establish in the emergency department (ED). CASE REPORT: This is a case report of missed eDKA in a 47-year-old male taking empagliflozin (a SGLT2 inhibitor) that presented to the ED with generalized weakness. His past medical history included multiple sclerosis (MS) diagnosed 4 years ago and type 2 diabetes mellitus. The patient attributed his weakness to MS. His neurologist was consulted and agreed with the plan to discharge the patient with diagnoses of asthenia and dehydration and a prescription of prednisone. The patient returned to the ED the next day with similar symptoms and was admitted to the hospital for treatment of eDKA. He was eventually treated per the hospital diabetic ketoacidosis (DKA) protocol and discharged home with instructions to discontinue empagliflozin. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: The increasing utilization of SGLT2 inhibitor in patients with type 2 diabetes mellitus will inevitably lead to more cases of eDKA seen in the ED. Emergency physicians need to consider this diagnosis in patients taking these medications that present with symptoms including weakness, nausea, vomiting, abdominal pain, and dehydration. Patients taking these medications should be warned about these symptoms, especially because they may be falsely reassured by relatively low plasma glucose levels on home glucometer readings.

Smoothness of stimulus motion can affect vection strength.

We examined the effect of the smoothness of motion on vection strength. The smoothness of stimulus motion was modulated by varying the number of frames comprising the movement. In this study, a horizontal grating translated through 360° of phase in 1 s divided into steps of 3, 4, 6, 12, 20, 30, or 60 frames. We hypothesized that smoother motion should induce stronger vection because the smoother stimulus is more natural and contains more motion energy. We examined this effect of frame number on vection for both downward (Experiment 1) and expanding (Experiment 2) optical flow. The results clearly showed that vection strength increased with increasing frame rate, however, the rates of increase in the vection strength with frame rate are not constant, but rapidly increase in the low frame-rate range and appear to asymptote in the high range. The strength estimates saturated at lower frame rates for expanding flow than for downward flow. This might be related to the fact that to process expanding flow it is necessary to integrate motion signals across the visual field. We conclude that the smoothness of the motion stimulus highly affects vection induction.

Assessment of hepatitis B immunization programme among school students in Qatar.

BACKGROUND: In 2010, Qatar adopted the target of reducing hepatitis B prevalence to < 1% in children by 2015. The World Health Organization Region for the Eastern Mediterranean is identified with intermediate hepatitis B virus (HBV) endemicity, ranging from 2% to 7%. It is estimated that 4.3 million individuals are living with HBV infection in the Region. AIMS: This study was conducted to assess hepatitis B seroprevalence in children, hepatitis B vaccination coverage, potential exposure to risk factors, and knowledge among parents/guardians about hepatitis B infection. METHODS: We carried out this cross-sectional study in Qatar during the academic year 2015/16. Multistage cluster sampling was used to select a nationally representative sample of 2735 grade 1 school students aged ≥ 5 years. Blood was collected by finger prick and tested using the point-of-care test/rapid test. A self-administered, precoded questionnaire was used to assess parent/guardian knowledge about HBV and collect information on the child's HBV vaccination coverage. RESULTS: All blood samples were HBsAg negative. Qataris had a vaccination card and were totally vaccinated but 17.7% of non-Qataris did not hold a vaccination card and most parents/guardians were not aware of the vaccination status of their children. Children were exposed to various hepatitis B risk practices. Knowledge about hepatitis B among parents/ guardians was low. CONCLUSIONS: Qatar has averted the hepatitis B threat and maintained high vaccination coverage for children.

Hair Loss: Common Causes and Treatment.

Hair loss is often distressing and can have a significant effect on the patient's quality of life. Patients may present to their family physician first with diffuse or patchy hair loss. Scarring alopecia is best evaluated by a dermatologist. Nonscarring alopecias can be readily diagnosed and treated in the family physician's office. Androgenetic alopecia can be diagnosed clinically and treated with minoxidil. Alopecia areata is diagnosed by typical patches of hair loss and is self-limited. Tinea capitis causes patches of alopecia that may be erythematous and scaly and must be treated systemically. Telogen effluvium is a nonscarring, noninflammatory alopecia of relatively sudden onset caused by physiologic or emotional stress. Once the precipitating cause is removed, the hair typically will regrow. Trichotillomania is an impulse-control disorder; treatment is aimed at controlling the underlying psychiatric condition. Trichorrhexis nodosa occurs when hairs break secondary to trauma and is often a result of hair styling or overuse of hair products. Anagen effluvium is the abnormal diffuse loss of hair during the growth phase caused by an event that impairs the mitotic activity of the hair follicle, most commonly chemotherapy. Physician support is especially important for patients in this situation.

Back to Basics: The Effect of Healthy Diet and Exercise on Chronic Disease Management.

INTRODUCTION: The increase in obesity rates in the U.S. and other less developed industrial countries have led to a worldwide epidemic of chronic disease states. Increased obesity rates are implicated in the treatment failures for illnesses such as coronary artery disease, diabetes, heart failure, hypertension and cancer. Effective prevention of obesity through diet and exercise contributes to the successful medical management of multiple chronic disease states. OBJECTIVE: Review the last 10 years of literature (2006-2016) on the effects of diet and exercise as they relate to the prevention of chronic disease. METHOD/DATA REVIEWED: Cochran Database of Systematic Reviews and other original articles using the National Center for Biotechnical Information database. CONCLUSION: The success in management of chronic disease lies in a physician's ability to educate patients and effective utilization of the resources available to that provider. Patient accountability for their individual chronic disease states is a problem related to patient education, patient participation, access to care, and payment resources. Financial, racial, and socioeconomic barriers must be addressed in the creation of an effective plan. Teaching on the importance of diet and exercise needs to occur early in life and be continually reinforced for successful outcomes. In the last 10 years, there has not been a significant study suggesting a single successful model of diet and exercise that can control chronic diseases. Cardiac, diabetic, and cancer patients have reduced hospital admissions, improved diabetic control, and improved quality of life scores related to coordinated diet and exercise programs, however. Patients may be unwilling or unable to be accountable for health care coordination. The development of exercise and obesity prevention policies and the adjustment in financial rewards to health care organizations will have a major impact in implementing these programs over the next 10 years.

Airborne Optical and Thermal Remote Sensing for Wildfire Detection and Monitoring.

For decades detection and monitoring of forest and other wildland fires has relied heavily on aircraft (and satellites). Technical advances and improved affordability of both sensors and sensor platforms promise to revolutionize the way aircraft detect, monitor and help suppress wildfires. Sensor systems like hyperspectral cameras, image intensifiers and thermal cameras that have previously been limited in use due to cost or technology considerations are now becoming widely available and affordable. Similarly, new airborne sensor platforms, particularly small, unmanned aircraft or drones, are enabling new applications for airborne fire sensing. In this review we outline the state of the art in direct, semi-automated and automated fire detection from both manned and unmanned aerial platforms. We discuss the operational constraints and opportunities provided by these sensor systems including a discussion of the objective evaluation of these systems in a realistic context.

Increased incidence of cancer and cancer-related mortality among persons with chronic hepatitis C infection, 2006-2010.

BACKGROUND & AIMS: Persons chronically infected with the hepatitis C virus (HCV) may be at higher risk for developing and dying from non-liver cancers than the general population. METHODS: 12,126 chronic HCV-infected persons in the Chronic Hepatitis Cohort Study (CHeCS) contributed 39,984 person-years of follow-up from 2006 to 2010 and were compared to 133,795,010 records from 13 Surveillance, Epidemiology and End Results Program (SEER) cancer registries, and approximately 12 million U.S. death certificates from Multiple Cause of Death (MCOD) data. Measurements included standardized rate ratios (SRR) and relative risk (RR). RESULTS: The incidence of the following cancers was significantly higher among patients with chronic HCV infection: liver (SRR, 48.6 [95% CI, 44.4-52.7]), pancreas (2.5 [1.7-3.2]), rectum (2.1 [1.3-2.8]), kidney (1.7 [1.1-2.2]), non-Hodgkin lymphoma (NHL) (1.6 [1.2-2.1]), and lung (1.6 [1.3-1.9]). Age-adjusted mortality was significantly higher among patients with: liver (RR, 29.6 [95% CI, 29.1-30.1]), oral (5.2 [5.1-5.4]), rectum (2.6 [2.5-2.7]), NHL (2.3 [2.2-2.31]), and pancreatic (1.63 [1.6-1.7]) cancers. The mean ages of cancer diagnosis and cancer-related death were significantly younger among CHeCS HCV cohort patients compared to the general population for many cancers. CONCLUSIONS: Incidence and mortality of many types of non-liver cancers were higher, and age at diagnosis and death younger, in patients with chronic HCV infection compared to the general population.

Update on polio eradication in the World Health Organization South-East Asia Region, 2013.

There has been a tremendous amount of progress toward polio eradication in the World Health Organization South-East Asia Region particularly over the past 4 years. In 1988, there were >25,000 reported cases of wild poliovirus infection in the South-East Asia Region, and because of substantial underreporting the estimated polio burden was probably 10-fold higher. Following the initiation of mass polio immunization campaigns in the mid-1990s and years of intense effort, the 11 countries of the South-East Asia Region reported no cases of wild poliovirus infection in 2012. With India reporting the last wild poliovirus case in the region, on 13 January 2011, and its subsequent removal from the list of polio-endemic countries, in February 2012, the South-East Asia Region is firmly on track for polio-free certification in early 2014.

Vergence eye movements are not essential for stereoscopic depth.

The brain receives disparate retinal input owing to the separation of the eyes, yet we usually perceive a single fused world. This is because of complex interactions between sensory and oculomotor processes that quickly act to reduce excessive retinal disparity. This implies a strong link between depth perception and fusion, but it is well established that stereoscopic depth percepts are also obtained from stimuli that produce double images. Surprisingly, the nature of depth percepts from such diplopic stimuli remains poorly understood. Specifically, despite long-standing debate it is unclear whether depth under diplopia is owing to the retinal disparity (directly), or whether the brain interprets signals from fusional vergence responses to large disparities (indirectly). Here, we addressed this question using stereoscopic afterimages, for which fusional vergence cannot provide retinal feedback about depth. We showed that observers could reliably recover depth sign and magnitude from diplopic afterimages. In addition, measuring vergence responses to large disparity stimuli revealed that that the sign and magnitude of vergence responses are not systematically related to the target disparity, thus ruling out an indirect explanation of our results. Taken together, our research provides the first conclusive evidence that stereopsis is a direct process, even for diplopic targets.