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Ice worlds are at the forefront of astrobiological interest because of the evidence of subsurface oceans. Enceladus in particular is unique among the icy moons because there are known vent systems that are likely connected to a subsurface ocean, through which the ocean water is ejected to space. An existing study has shown that sending small robots into the vents and directly sampling the ocean water is likely possible. To enable such a mission, NASA's Jet Propulsion Laboratory is developing a snake-like robot called Exobiology Extant Life Surveyor (EELS) that can navigate Enceladus' extreme surface and descend an erupting vent to capture unaltered liquid samples and potentially reach the ocean. However, navigating to and through Enceladus' environment is challenging: Because of the limitations of existing orbital reconnaissance, there is substantial uncertainty with respect to its geometry and the physical properties of the surface/vents; communication is limited, which requires highly autonomous robots to execute the mission with limited human supervision. Here, we provide an overview of the EELS project and its development effort to create a risk-aware autonomous robot to navigate these extreme ice terrains/environments. We describe the robot's architecture and the technical challenges to navigate and sense the icy environment safely and effectively. We focus on the challenges related to surface mobility, task and motion planning under uncertainty, and risk quantification. We provide initial results on mobility and risk-aware task and motion planning from field tests and simulated scenarios.

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We have investigated the temperature dependence of the optical reflectivity on a femtosecond scale in a near optimally doped YBa 2Cu 3O (7-delta) superconductor. The combined study of the lattice and carrier dynamics at temperatures above T(c) allows us to identify two crossover temperatures in the normal state, giving evidence for an inhomogeneity of the pseudogap regime. These crossovers exhibit a clear hysteresis behavior depending on the direction of temperature change. The carrier and lattice dynamics within the crossover regimes show distinct differences from and similarities to the superconducting state, which may help in choosing between the competing theories for the pseudogap state.

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Peripheral retinal abnormalities detected in examinations of 4840 patients with myopia are analyzed. The incidence of subclinical detachments of the retina was 8.7%. Two-staged laser therapy of detachments and its results are discussed and laser refraction operations in such abnormalities of the fundus oculi are considered. Results of photorefraction operations of different types in patients previously operated on the retina by the laser method are analyzed. Only 5 patients needed repeated laser therapy on the fundus oculi during 3 years postoperation. Hence, photorefraction correction of refraction abnormalities can be carried out in patients with subclinical detachments of the retina after previous effective laser therapy.

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Pathological changes in the retina in myopia of 1.5-17 diopters are analyzed, based on analysis of more than 4800 cases. Detachments of the retina were responsible for 0.5% cases. Photocoagulation of the retina was carried out using 2 lasers: diode DC-3000 NIDEK (790-830 nm) and Nd-YAG Alcon (532 nm). Photorefraction operations of two types (photorefraction keratectomy and LASIK) were carried out on a Nidek EC-5000 laser. The results evidence a possibility of photorefraction operations for correction of myopia 6 months to 11 years after a previous intervention for detachment of the retina (21 operations). Visual acuity without correction was 0.69 +/- 0.08, spherical equivalent of clinical refraction 0.80 +/- 0.34. Repeated laser coagulation at the retinal periphery for blocking newly forming ruptures was needed in 14.2% cases. No relapses occurred during 3 years postoperation.

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The problem of retinal detachment prevention is closely connected with a competent diagnosis of peripheral vitreochorioretinal dystrophies (PVCRD). The present research was aimed at analysis of PVCRD incidence in myopia of various degree and of the incidence of pathologic shifts requiring prophylactic laser coagulation or cryopexy. A total of 1022 patients (2044 eyes) with myopia of various degrees aged 5 to 58 were examined. Sclerocompression method was used in ophthalmoscopy in all the cases. PVCRD were diagnosed in 73.2% of patients. The detection rate of this condition was directly proportional to myopia degree; 52.6% in weak myopia, 70.7% in medium-grave myopia, 86.4% in high myopia. The detected patients with PVCRD were in need of preventive treatment whatever myopia degree: 38.7% of those with weak myopia, 46.9% of those with medium-grave myopia, and 46.5% of those with high myopia, 42.4% of patients with myopia on an average. Detachment of the retina was diagnosed in 4% of patients with myopia, in 0.5% surgical treatment of this condition was needed, and in 3.5% it was subclinical, this permitting a prophylactic laser coagulation.

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The experience of the district hospital in Stara Zagora in the treatment of patients with systemic connective tissue diseases for the period 1976-1986 is presented. The study includes 47 patients with systemic connective tissue diseases: 22 patients with systemic lupus erythematodes (19 alive, 3 deceased); 18 patients with systemic progressive sclerodermia (16 alive, 2 deceased); 5 patients with dermatomyositis (4 alive, I deceased); 2 patients with nodal polyarteriitis (I alive, I deceased). The characteristic of the course of the disease is discussed--acute, subacute and chronic. The treatment applied and the cause of death are analyzed. The mean duration of the disease from the first clinical signs for the alive and the deceased is as follows: systemic lupus erythematodes--13.7 years for the alive and 12.5 years for the deceased patients; systemic progressive sclerodermia--16.6 years for the alive and 3.0 years for the deceased patients; dermatomyositis--3.7 years for the alive, 1.5 years for the deceased patients; polyarteritis nodosa--5 years for the alive, 2 years for the deceased patients. The conclusion is reached that the contemporary treatment can lead to a remission even in severe cases and life-threatening forms of the disease.

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The authors conducted a scintigraphic study of 50 patients with a 2-7 year history of myocardial infarction and clinical findings of postinfarction myocardiofibrosis. 201Tl-chloride with the activity of 74 MBq and the Picker 500 magna-scanner (USA) were employed. Four projections were used in the study. It was stressed that in anterior myocardial infarction the best positions were the front and front-left-oblique ones (30 and 45 degrees) and in posterior myocardial infarction the front-left-oblique one (75 degrees). A conclusion has been made as to a high sensitivity of the method to confirm postinfarction myocardiofibrosis represented in the form of a zone with disturbed perfusion. The authors underlined a high value of the method in cases accompanied by conductive disorders as the information value of a scintigram exceeded that of ECG.

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Present-day data (histological, electrocardiographic, vectorcardiographic and coronarographic) are presented in the paper, forming the concept of quadrifascicular structure of the conduction system of the heart. The criteria are indicated, on which the diagnostics of blocking of anterior-medial ramification of the left branch of His bundle is based. The author presents 4 of his own observations, illustrating the variety of the manifestations of the blocking of the anterior-medial ramulus--intermittent blocking, combination with blocking of anterior-upper ramulus, blocking in the presence of only septal fibres of the ramulus and blocking with spreading of the fibres also in the anterior-septal region of the left ventricle of heart.

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Auricular dissociation is a rare and interesting arrhythmia, characterized by ectopic auricular thythm, independent of the basic one. The basic and accessory auricular rhythm never interfere in between, the latter always being restricted to a smaller part of auricle and is almost never conducted to ventricles. It is most frequently a slow rhythm, and is rarely recorded as auricular fibrillation and undulation of one auricle, or as auricular tachycardia. Almost always the auricular dissociation develops in critical states and most frequently appears several hours prior to a lethal end. A typical case of auricular dissociation is described in a male subject with active myocardial infarction that originated several hours prior to the lethal end of the patient. In our case a rare variant of auricular dissociation is concerned, combined with AV dissociation.

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