Planetary system detection by estimating the covariance of coronagraphic lucky images

2019 ◽  
Vol 488 (3) ◽  
pp. 3262-3267
Author(s):  
Miguel A Cagigas ◽  
Manuel P Cagigal ◽  
Pedro J Valle ◽  
Vidal F Canales ◽  
Antonio Fuentes ◽  
...  
Keyword(s):  
Dynamic Range ◽  
Planetary System ◽  
Image Contrast ◽  
The Other ◽  
Magnitude Range ◽  
Other Hand ◽  
William Herschel ◽  
Proven Method

ABSTRACT In this paper, we review two different methods to increase image contrast and propose the combination of both to detect faint companions surrounding a host star. Coronagraphy allows us to block light coming from the host star so that the residual star light can be reduced by several orders of magnitude. On the other hand, estimating the Covariance of Lucky Images (COELI) is a proven method to detect faint companions from ground-based telescope images. The dynamic range of the detection camera limits this technique. Hence, the application of COELI to coronagraphic images may increase the magnitude range of the detectable companions. COELI only requires the existence of a reference, which can be obtained using an existing stellar companion or using a coronagraphic mask designed to create a faint image of the host star. We provide an analysis of the combination of the techniques by processing coronagraphic images obtained by the William Herschel Telescope.

A closer look at the September 16, 1732, Montreal earthquake

1981 ◽  
Vol 18 (3) ◽  
pp. 539-550 ◽  
Author(s):  
Gabriel Leblanc
Keyword(s):  
Seismic Hazard ◽  
The Other ◽  
Limited Information ◽  
Earthquake Occurrence ◽  
Earthquake Catalogues ◽  
Magnitude Range ◽  
Other Hand ◽  
Epicentral Intensity

The September 16, 1732, earthquake ranks among the three largest events in the western Quebec zone of earthquake occurrence and thus plays a controlling role in seismic hazard studies of the region. Its epicentral intensity has been estimated differently by various authors of earthquake catalogues, mostly because limited information was available. Recently, additional evidence was uncovered and evaluated. It suggests that an epicentral intensity VIII (modified Mercalli) is adequately representative of the damage observed in Montreal and agrees well with the other distant felt reports. On that basis, the intensity IX (MM) found in some catalogues should be revised; on the other hand, the Montreal location appears to be the most acceptable. It is proposed that the event be also characterized in terms of an estimated magnitude range, i.e., 5.6–6.0 [Formula: see text].

scholarly journals Метод маскувального ущільнення службових даних в системах компресії відеозображень

2021 ◽  
pp. 51-63
Author(s):  
Володимир Вікторович Бараннік ◽  
Сергій Олександрович Сідченко ◽  
Наталія Вячеславівна Бараннік ◽  
Андрій Михайлович Хіменко
Keyword(s):  
Video Compression ◽  
Dynamic Range ◽  
Structural Characteristics ◽  
Video Data ◽  
The Other ◽  
Service Component ◽  
Redundant Data ◽  
Other Hand ◽  
Service Components ◽  
Service Data

The demand for video privacy is constantly increasing. Simultaneously, it is necessary to solve an urgent scientific and applied problem, which consists in increasing the confidentiality of video information under conditions of a given time delay for its processing and delivery, while ensuring its reliability. The crypto compression transformations can be used to solve it. A service component is used as a conversion key, which is directly formed in the conversion process and contains information about the identified structural characteristics of the video data. Therefore, such information requires confidentiality. The existing methods of cryptography are designed to process a universal data stream and do not consider the structure and features of service components. It leads to the formation of redundant data, the use of an excessive number of operations, and an increase in processing time in the process of protecting service information using universal cryptography methods. Therefore, the article aims to develop a method for masking service data compression to ensure their confidentiality, considering the peculiarities of their formation by crypto compression methods. In modes with controlled loss of information quality, the elements of the service component are formed in a reduced dynamic range. Their length is 7 bits. To ensure the confidentiality of such elements, it is necessary to develop a method for masking overhead compression in video compression systems. On the one hand, overhead blocks should not contain redundant information. On the other hand, they must be formed from bit positions from different elements of the service components. On the other hand, they should be formed from bit positions from different elements of the service components. For that, it is proposed to organize the assembly of the elements of the service components. It is organized by combining 7-bit elements of service components into 8-bit complete sequences. Encryption blocks are formed from 8-bit sequences. The assembly of service components ensures the mixing of service data and reducing their quantity. To violate the structure of the representation of service components, it is proposed to additionally organize the permutation of 8-bit completed sequences. It provides a significant dispersion of the bit positions of the 7-bit overhead elements and the destruction of the correlation between the overhead elements. The correlation coefficients of the original and reconstructed images using encrypted service components are in the region of 0. The number of changing pixels is above the theoretical threshold value of 99.5341%.

Direct Analysis of Spectra by Image Isocon and Computer

1971 ◽  
Vol 11 ◽  
pp. 86-89
Author(s):  
G. A. H. Walker ◽  
J. R. Auman ◽  
V. Buchholz ◽  
B. Goldberg ◽  
B. Isherwood
Keyword(s):  
Quantum Efficiency ◽  
Spatial Resolution ◽  
Dynamic Range ◽  
Direct Analysis ◽  
The Other ◽  
Digital Form ◽  
Other Hand ◽  
Imaging Detectors ◽  
Photographic Emulsions ◽  
Reciprocity Failure

Astronomical spectra are, with few exceptions, still being recorded on photographic emulsions. These generally have the advantages of better spatial resolution and larger available area than existing photoelectric imaging detectors. On the other hand they do suffer from a small dynamic range (15 or 20: 1), reciprocity failure, and a quantum efficiency of less than 1 per cent. Image intensifiers and image orthocons can be used to improve sensitivity, but where photographs are used for the record the other problems tend to remain. Calibration and extraction of the appropriate astronomical information in digital form involves a considerable amount of time and careful work, as one can appreciate from many of the papers presented at this colloquium.

Sequential Homography-Based Alignment for HDR Image Generation

2012 ◽  
Vol 452-453 ◽  
pp. 1025-1029
Author(s):  
Luigi Barazzetti ◽  
Fabio Remondino ◽  
Marco Scaioni
Keyword(s):  
Dynamic Range ◽  
Digital Camera ◽  
High Dynamic Range ◽  
The Other ◽  
Image Generation ◽  
Registration Algorithm ◽  
Other Hand ◽  
Standard Solution ◽  
High Dynamic ◽  
Hdr Image

Tripoding the camera is a standard solution to acquire aligned images useful for High Dynamic Range photography. On the other hand, the chance to use a hand-held digital camera is surely more practical and attractive for photographers. In this paper we propose a registration algorithm that recovers the alignment of several bracketed images using a progressive combination of homographies estimated from a set of image correspondences.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

Life Beyond 1MeV

1980 ◽  
Vol 38 ◽  
pp. 30-33
Author(s):  
K.H. Westmacott
Keyword(s):  
Electron Microscopy ◽  
Past Experience ◽  
The Other ◽  
Good Case ◽  
Other Hand ◽  
The U.S

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.

Can the Academic Self-Concept be Positive and Realistic?

2005 ◽  
Vol 19 (3) ◽  
pp. 129-132 ◽  
Author(s):  
Reimer Kornmann
Keyword(s):  
Academic Performance ◽  
Opposite Effect ◽  
Self Esteem ◽  
Point Of View ◽  
The Other ◽  
Self Concept ◽  
High Ability ◽  
Self Image ◽  
Other Hand

Summary: My comment is basically restricted to the situation in which less-able students find themselves and refers only to literature in German. From this point of view I am basically able to confirm Marsh's results. It must, however, be said that with less-able pupils the opposite effect can be found: Levels of self-esteem in these pupils are raised, at least temporarily, by separate instruction, academic performance however drops; combined instruction, on the other hand, leads to improved academic performance, while levels of self-esteem drop. Apparently, the positive self-image of less-able pupils who receive separate instruction does not bring about the potential enhancement of academic performance one might expect from high-ability pupils receiving separate instruction. To resolve the dilemma, it is proposed that individual progress in learning be accentuated, and that comparisons with others be dispensed with. This fosters a self-image that can in equal measure be realistic and optimistic.

Stories and the Self

2020 ◽  
Vol 32 (2) ◽  
pp. 47-58 ◽  
Author(s):  
Stefan Krause ◽  
Markus Appel
Keyword(s):  
Meta Analysis ◽  
The Self ◽  
The Other ◽  
Lower Degree ◽  
Contrast Effects ◽  
Self Perception ◽  
Self Perceptions ◽  
Other Hand ◽  
The One ◽  
Implicit And Explicit

Abstract. Two experiments examined the influence of stories on recipients’ self-perceptions. Extending prior theory and research, our focus was on assimilation effects (i.e., changes in self-perception in line with a protagonist’s traits) as well as on contrast effects (i.e., changes in self-perception in contrast to a protagonist’s traits). In Experiment 1 ( N = 113), implicit and explicit conscientiousness were assessed after participants read a story about either a diligent or a negligent student. Moderation analyses showed that highly transported participants and participants with lower counterarguing scores assimilate the depicted traits of a story protagonist, as indicated by explicit, self-reported conscientiousness ratings. Participants, who were more critical toward a story (i.e., higher counterarguing) and with a lower degree of transportation, showed contrast effects. In Experiment 2 ( N = 103), we manipulated transportation and counterarguing, but we could not identify an effect on participants’ self-ascribed level of conscientiousness. A mini meta-analysis across both experiments revealed significant positive overall associations between transportation and counterarguing on the one hand and story-consistent self-reported conscientiousness on the other hand.

Don’t Put Me in This Group

2019 ◽  
Vol 50 (2) ◽  
pp. 80-93
Author(s):  
Jort de Vreeze ◽  
Christina Matschke
Keyword(s):  
Positive Emotions ◽  
Negative Emotions ◽  
Negative Information ◽  
The Self ◽  
The Other ◽  
Other Hand ◽  
Group Memberships

Abstract. Not all group memberships are self-chosen. The current research examines whether assignments to non-preferred groups influence our relationship with the group and our preference for information about the ingroup. It was expected and found that, when people are assigned to non-preferred groups, they perceive the group as different to the self, experience negative emotions about the assignment and in turn disidentify with the group. On the other hand, when people are assigned to preferred groups, they perceive the group as similar to the self, experience positive emotions about the assignment and in turn identify with the group. Finally, disidentification increases a preference for negative information about the ingroup.

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