Results of comparing astronomical-geodetic and navigational-geodetic methods of determining the components of the deflection of vertical

The authors present the results of comparing the components of deflection of vertical obtained through astronomical-geodetic and navigational-geodetic methods. The first one is based on comparing astronomical and geodetic coordinates of a location. This method has recently been widely implemented in a digital zenith camera systems using a small-sized digital telescope with an astronomical camera based on CCD or CMOS technologies, a high-precision inclinometer and satellite navigation system receiver. In this case, the combination of a telescope, an astronomical camera and an inclinometer enables determining the local direction of the plumb line, expressed by astronomical coordinates, from observations of stars at the zenith and using high-precision star catalogs. The navigational-geodetic method is based on comparing the results of the normal heights’ increments, defined through geometric leveling, and geodetic heights, computed with the relative method of satellite coordinate determinations. For each method, random and systematic components of the error and its confidence bounds were calculated; the absolute values of the deflection of vertical components at two geographically separated points were compared.

An optimal population code for global motion estimation in local direction-selective cells

Nervous systems allocate computational resources to match stimulus statistics. However, the physical information that needs to be processed depends on the animal's own behavior. For example, visual motion patterns induced by self-motion provide essential information for navigation. How behavioral constraints affect neural processing is not known. Here we show that, at the population level, local direction-selective T4/T5 neurons in Drosophila represent optic flow fields generated by self-motion, reminiscent to a population code in retinal ganglion cells in vertebrates. Whereas in vertebrates four different cell types encode different optic flow fields, the four uniformly tuned T4/T5 subtypes described previously represent a local snapshot. As a population, six T4/T5 subtypes encode different axes of self-motion. This representation might serve to efficiently encode more complex flow fields generated during flight. Thus, a population code for optic flow appears to be a general coding principle of visual systems, but matching the animal's individual ethological constraints.

Potential of competitive environment: methodological aspect

The purpose of the article is to justify a new systemic scientific approach to building a competitive environment as a base framework for strengthening competitive positions in the system of socio-economic systems. Research methodology. The methodology of the systematic-integrated approach to development of the competitive environment as a integrity in the organic unity of the formed preconditions for the effective activity of the subjects of civilized market direction is proposed. Scientific novelty consists in justification: prerequisites as a fundamental basis for ensuring the development of a competitive environment as a systemic integrity in the organic unity of production components, functionally attendants, innovation, investment, self-regulatory and other direction; Potential of the competitive environment and its force field, target installations, policy, in the areas and activities. The potential for development of the competitive environment is considered as systemic integrity, which covers: the basic prerequisites for 10 positions ensuring the effectiveness of the activities of market subjects; The list of challenges of competitive activity of market subjects for 7 positions in context of social responsibility; Main activities and directions of development (30 positions); Methodological approach to the policy review from the position of competitiveness of the general system and local direction in 30 business areas. Conclusions. As a result of the study, it is concluded that the potential for competitive environment development can be ensured through the use of the systematic-integrated approach to the formation of its components as a whole on the basis of justification: preconditions in the organic unity of production, functionally-providing orientation; Innovative, investment, regulatory, self-regulatory, and other direction; Value orientations and target installations; Implementation of tasks of social, organizational, intellectual, economic and other direction in systemic integrity; Developed system of effective demand; Policy on the directions of development of the activities allocated by us.

Multi-Scale LG-Mod Analysis for a More Reliable SAR Sea Surface Wind Directions Retrieval

An improved version of the Local-Gradient-Modified (LG-Mod) algorithm for Sea Surface Wind (SSW) directions retrieval by means of Synthetic Aperture Radar (SAR) images is presented. A “local” multi-scale analysis of wind-aligned SAR patterns is introduced to improve the LG-Mod sensitivity to SAR backscattering modulations, occurring locally with various spatial wavelengths. The Marginal Error parameter is redefined, and the adoption of the Directional Accuracy Maximization Criterion (DAMC) allows for the novel Multi-Scale (MS) LG-Mod to automatically select the local processing scale that may be regarded as optimal for pattern enhancement, once a discrete set of scales has been already fixed. Hence, this optimal scale successfully gives evidence to guarantee the best achievable local direction estimation. The assessment of the MS LG-Mod is carried on both simulated SAR images and a Sentinel-1 (S-1) dataset, consisting of 350 Interferometric Wide Swath Ground Range Multi-Look Detected High-Resolution images, which cover the region of the Gulf of Maine. In the latter case, the removal of artifacts and non-wind features from SAR amplitudes is mandatory before directional estimations. In situ wind observations gathered by the National Oceanic and Atmospheric Administration National Data Buoy Center (NOAA NDBC) are exploited for validation. The findings obtained from S-1 data confirm the ones from simulated patterns. The MS LG-Mod analysis performs better than each single-scale one in terms of both percentages of reliable directions and directional Root Mean Square Error (RMSE) values achieved.

Rapid ‘multi-directed’ cholinergic transmission at central synapses

Acetylcholine (ACh) is a key neurotransmitter that plays diverse roles in many parts of the central nervous system, including the retina. However, assessing the precise spatiotemporal dynamics of ACh is technically challenging and whether ACh transmits signals via rapid, point-to-point synaptic mechanisms, or broader-scale ‘non-synaptic’ mechanisms has been difficult to ascertain. Here, we examined the properties of cholinergic transmission at individual contacts made between direction-selective starburst amacrine cells and downstream ganglion cells in the retina. Using a combination of electrophysiology, serial block-face electron microscopy, and two-photon ACh imaging, we demonstrate that ACh signaling bears the hallmarks of both non-synaptic and synaptic forms of transmission. ACh co-activates nicotinic ACh receptors located on the intersecting dendrites of pairs of ganglion cells, with equal efficiency (non-synaptic)— and yet retains the ability to generate rapid ‘miniature’ currents (∼1 ms rise times: synaptic). Fast cholinergic signals do not appear to depend on anatomically well-defined synaptic structures. We estimate that ACh spread is limited to ∼1-2 µm from its sites of release, which may help starbursts drive local direction-selective cholinergic responses in ganglion cell dendrites. Together, our results establish the functional architecture for cholinergic signaling at a central synapse and propose a novel motif whereby single presynaptic sites can co-transmit information to multiple neurons on a millisecond timescale.

Automatic detection and extraction algorithm of coronal loops based on match filter and oriented directivity

ABSTRACT In this paper, an efficient algorithm is developed to automatically detect and extract coronal loops. First of all, in the algorithm, three characteristics associated with coronal loops are used to construct a match filter able to enhance the loops. Secondly, the method combining a high-pass filter (unsharp-mask enhancement) with a global threshold is used to further enhance and segment the loops. Thirdly, to extract every individual coronal loop and obtain their parameters (the 2D projected space coordinates and lengths) from the segmented loops, a clustering method of the pixels with approximate local direction and connected domain is further used. Fourthly, to evaluate the performance of the developed algorithm, images observed by the Transition Region and Coronal Explorer (TRACE), the Atmospheric Imaging Assembly (AIA) of the Solar Dynamics Observatory (SDO) and the High-Resolution Coronal Imager (Hi-C) are used, and comparison experiments between the existing algorithms and the developed algorithm are performed. Finally, it is found that the developed algorithm is commensurate with the two most promising algorithms, oriented coronal curved loop tracing (OCCULT) and its improved version, OCCULT-2, in performance. Therefore, for scientific applications associated with coronal loops, the developed algorithm will be a powerful tool.