Perspective Preserving Solution for Quasi-Orthoscopic Video See-Through HMDs

In non-orthoscopic video see-through (VST) head-mounted displays (HMDs), depth perception through stereopsis is adversely affected by sources of spatial perception errors. Solutions for parallax-free and orthoscopic VST HMDs were considered to ensure proper space perception but at expenses of an increased bulkiness and weight. In this work, we present a hybrid video-optical see-through HMD the geometry of which explicitly violates the rigorous conditions of orthostereoscopy. For properly recovering natural stereo fusion of the scene within the personal space in a region around a predefined distance from the observer, we partially resolve the eye-camera parallax by warping the camera images through a perspective preserving homography that accounts for the geometry of the VST HMD and refers to such distance. For validating our solution; we conducted objective and subjective tests. The goal of the tests was to assess the efficacy of our solution in recovering natural depth perception in the space around said reference distance. The results obtained showed that the quasi-orthoscopic setting of the HMD; together with the perspective preserving image warping; allow the recovering of a correct perception of the relative depths. The perceived distortion of space around the reference plane proved to be not as severe as predicted by the mathematical models

Optical See-Through Head-Mounted Displays With Short Focal Distance: Conditions for Mitigating Parallax-Related Registration Error

Optical see-through (OST) augmented reality head-mounted displays are quickly emerging as a key asset in several application fields but their ability to profitably assist high precision activities in the peripersonal space is still sub-optimal due to the calibration procedure required to properly model the user's viewpoint through the see-through display. In this work, we demonstrate the beneficial impact, on the parallax-related AR misregistration, of the use of optical see-through displays whose optical engines collimate the computer-generated image at a depth close to the fixation point of the user in the peripersonal space. To estimate the projection parameters of the OST display for a generic viewpoint position, our strategy relies on a dedicated parameterization of the virtual rendering camera based on a calibration routine that exploits photogrammetry techniques. We model the registration error due to the viewpoint shift and we validate it on an OST display with short focal distance. The results of the tests demonstrate that with our strategy the parallax-related registration error is submillimetric provided that the scene under observation stays within a suitable view volume that falls in a ±10 cm depth range around the focal plane of the display. This finding will pave the way to the development of new multi-focal models of OST HMDs specifically conceived to aid high-precision manual tasks in the peripersonal space

Off-Line Camera-Based Calibration for Optical See-Through Head-Mounted Displays

In recent years, the entry into the market of self contained optical see-through headsets with integrated multi-sensor capabilities has led the way to innovative and technology driven augmented reality applications and has encouraged the adoption of these devices also across highly challenging medical and industrial settings. Despite this, the display calibration process of consumer level systems is still sub-optimal, particularly for those applications that require high accuracy in the spatial alignment between computer generated elements and a real-world scene. State-of-the-art manual and automated calibration procedures designed to estimate all the projection parameters are too complex for real application cases outside laboratory environments. This paper describes an off-line fast calibration procedure that only requires a camera to observe a planar pattern displayed on the see-through display. The camera that replaces the user’s eye must be placed within the eye-motion-box of the see-through display. The method exploits standard camera calibration and computer vision techniques to estimate the projection parameters of the display model for a generic position of the camera. At execution time, the projection parameters can then be refined through a planar homography that encapsulates the shift and scaling effect associated with the estimated relative translation from the old camera position to the current user’s eye position. Compared to classical SPAAM techniques that still rely on the human element and to other camera based calibration procedures, the proposed technique is flexible and easy to replicate in both laboratory environments and real-world settings

Hybrid Video/Optical See-Through HMD

An old but still ongoing subject of debate among augmented reality (AR) experts is about which see-through paradigm is best in wearable AR displays. Video see-through (VST) and optical see-through (OST) paradigms have both their own strengths and shortcomings with respect to technological and human-factor aspects. The major difference between these see-through paradigms is in providing an aided (VST) or unaided (OST) view of the real world. In this work, we present a novel approach for the development of AR stereoscopic head-mounted displays (HMDs) that can provide both the see-through mechanisms. Our idea is to dynamically modify the transparency of the display through a liquid crystal (LC)-based electro-optical shutter applied on the top of a standard OST device opportunely modified for housing a pair of external cameras. A plane-induced homography transformation is used for consistently warping the video images, hence reducing the parallax between cameras and displays. An externally applied drive voltage is used for smoothly controlling the light transmittance of the LC shutters so as to allow an easy transition between the unaided and the camera-mediated view of the real scene. Our tests have proven the efficacy of the proposed solution under worst-case lighting conditions

Laparoscopic bilateral hand-assisted nephrectomy: end-stage renal disease from tuberculosis, an unusual indication for nephrectomy before transplantation.

The purpose of the study was to sterilize renal tuberculous foci in a pretransplantation patient with a laparoscopic hand-assisted approach and to verify the feasibility of bilateral nephrectomy for this indication. This case report is the first description of hand-assisted laparoscopic bilateral nephrectomy for this pathologic condition. The 33-year-old patient had end-stage renal disease from renal tuberculosis. A commercially available hand-assistance device was used through a midline 8-cm supraumbilical incision and with four ports. The procedure was successfully completed. The total operative time was 3 hours and 40 minutes. Estimated blood loss was 250 mL. The postoperative course was uneventful, and clinical follow-up at 3 weeks revealed a successful outcome. Hand-assisted bilateral laparoscopic nephrectomy in patients with chronic renal failure from tuberculosis represents a viable option because it is feasible and effective. The hand-assisted approach increases the safety of the procedure while retaining all the advantages of minimally invasive surgery

CEUS Retrograde Cystography Is Helpful in Percutaneous Drainage of Complex Posttransplant Lymphocele

After monolateral dual kidney transplantation, a 69 years old male patient developed symptomatic lymphocele with mild hydroureteronephrosis, impaired renal function, and right inferior limb oedema. A percutaneous ultrasound-guided drainage of the fluid collection was planned, but the complex mutual relations between the collection and the renal hilus did not allow to identify a suitable route for a safe drainage insertion during conventional ultrasound examination. A retrograde cystography using echographic contrast agent was, therefore, performed, and it clarified the position of both ureters and the renal vessels, permitting an harmless ultrasound-guided percutaneous lymphocele drainage. In conclusion contrast-enhanced ultrasound retrograde cystography may be helpful in percutaneous drainage of complex posttransplant lymphocele

Aquaporin-6 Expression in the Cochlear Sensory Epithelium Is Downregulated by Salicylates

We characterize the expression pattern of aquaporin-6 in the mouse inner ear by RT-PCR and immunohistochemistry. Our data show that in the inner ear aquaporin-6 is expressed, in both vestibular and acoustic sensory epithelia, by the supporting cells directly contacting hair cells. In particular, in the Organ of Corti, expression was strongest in Deiters' cells, which provide both a mechanical link between outer hair cells (OHCs) and the Organ of Corti, and an entry point for ion recycle pathways. Since aquaporin-6 is permeable to both water and anions, these results suggest its possible involvement in regulating OHC motility, directly through modulation of water and chloride flow or by changing mechanical compliance in Deiters' cells. In further support of this role, treating mice with salicylates, which impair OHC electromotility, dramatically reduced aquaporin-6 expression in the inner ear epithelia but not in control tissues, suggesting a role for this protein in modulating OHCs' responses

Nocardiosis in a Kidney-Pancreas Transplant

34-year-old man with chronic renal and pancreas failure in complicated diabetic disease received a kidney-pancreas transplantation. On the 32nd postoperative day, an acute kidney rejection occurred and resolved with OKT3 therapy. The patient also presented refractory urinary infection by E. Fecalis and M. Morganii, and a focal bronchopneumonia in the right-basal lobe resolved with elective chemotherapy. During the 50th post-operative day, an intense soft tissue inflammation localized in the first left metatarsal-phalangeal articulation occurred (Figure 1) followed by an abscess with a cutaneous fistula and extension to the almost totality of foot area. The radiological exam revealed a small osteo-lacunar image localized in the proximal phalanx head of the first finger foot. From the cultural examination of the purulent material, N. Asteroides was identified. An amoxicillin-based treatment was started and continued for three months, with the complete resolution of infection This case is reported for its rarity in our casuistry, and for its difficult differential diagnosis with other potentially serious infections

A human-neutral large carnivore? No patterns in the body mass of gray wolves across a gradient of anthropization

The gray wolf (Canis lupus) expanded its distribution in Europe over the last few decades. To better understand the extent to which wolves could re-occupy their historical range, it is important to test if anthropization can affect their fitness-related traits. After having accounted for ecologically relevant confounders, we assessed how anthropization influenced i) the growth of wolves during their first year of age (n = 53), ii) sexual dimorphism between male and female adult wolves (n = 121), in a sample of individuals that had been found dead in Italy between 1999 and 2021. Wolves in anthropized areas have a smaller overall variation in their body mass, during their first year of age. Because they already have slightly higher body weight at 3–5 months, possibly due to the availability of human-derived food sources. The difference in the body weight of adult females and males slightly increases with anthropization. However, this happens because of an increase in the body mass of males only, possibly due to sex-specific differences in dispersal and/or to “dispersal phenotypes”. Anthropization in Italy does not seem to have any clear, nor large, effect on the body mass of wolves. As body mass is in turn linked to important processes, like survival and reproduction, our findings indicates that wolves could potentially re-occupy most of their historical range in Europe, as anthropized landscapes do not seem to constrain such of an important life-history trait. Wolf management could therefore be needed across vast spatial scales and in anthropized areas prone to social conflicts

Data Mining Tool for Academic Data Exploitation : Publication Report on Engineering Students Profiles

This document aims to reflect the results obtained at SPEET project by means of the application of the deployed data mining tools. More specifically, the application of the student performance tools on the engineering degrees by the participating institutions. The analysis can be used twofold: Example on the use of the different performance analysis tools developed on the project and accessible at the project web tool. Example on the interpretation of the clustering and analysis tools in order to delimit a student profile. The provided analysis also extends the interpretations aiming at showing similarities country wise, so, finally we can conclude that the tools developed in this project can offer some significant information in detecting different profiles and the relationship between these profiles and categorical variables such as age, admission score, sex, previous studies