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474842. The space of compact operators contains $c_0$ when a noncompact operator is suitably factorized
- Creator:
- Emmanuele, Giovanni and John, Kamil
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- spaces of linear operators, copies of $c_0$, and approximation properties
- Language:
- English
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
474843. The spatial correlation between the spread of COVID-19 and vulnerable urban areas in Santiago de Chile
- Creator:
- Vergara-Perucich, Francisco, Correa-Parra, Juan, and Aguirre-Nuñez, Carlos
- Format:
- počítač and online zdroj
- Type:
- model:article and TEXT
- Subject:
- housing in developing countries, urban policy and planning, residential context of health, and housing economics
- Language:
- English
- Description:
- This article identifies the spatial correlation between the social determinants of health in the housing area (housing prices, overcrowding, poor-quality building materials, and household socioeconomic vulnerability) and the spread of COVID-19 in Santiago de Chile. The research used data from the 2017 Census conducted by the National Institute of Statistics of Chile and data on confirmed cases of COVID-19 (PCR) by communes provided by/obtained from Chile’s Ministry of Health. The article provides a two-fold examination/analysis of the spatial correlation using the Pearson measure to observe how the virus spread from areas with high-quality housing in the early stage of the contagion to then become concentrated in areas with low-quality of housing. The second examination/analysis is a multiple linear regression to identify the housing factors that inform virus propagation. The test results show that of the four social determinants of health relating to housing assessed here, housing prices is the variable that best predicts how the social determinants of health based on housing explain the progress of the pandemic for the Santiago case, following the collinearity factors according to the data used in this study. The conclusions suggest that public policy should treat housing quality as a factor in public health and health risks that needs to be addressed with a transdisciplinary approach to urban planning in Chile.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
474844. The spatial distribution of leaf galls of Mikiola fagi (Diptera: Cecidomyiidae) and Neuroterus quercusbaccarum (Hymenoptera: Cynipidae) in the canopy of a Central European mixed forest
- Creator:
- Kampichler, Christian and Teschner, Markus
- Type:
- article, model:article, and TEXT
- Subject:
- Mikiola fagi, Neuroterus quercusbaccarum, galls, spatial distribution, host preference, canopy, oak, and beech
- Language:
- English
- Description:
- Despite their wide distribution and frequent occurrence, the spatial distribution patterns of the well-known gall-inducing insects Mikiola fagi (Hartig) and Neuroterus quercusbaccarum (L.) in the canopies of mature trees are poorly described. We made use of the Swiss Canopy Crane (SCC) near Basel, Switzerland, to gain access to the canopy of a mixed temperate forest up to a height of 35 m. Within one and a half days we scanned 6,750 beech leaves and 6,000 oak leaves. M.fagi showed a distinct vertical zonation with highest abundance in the top-most parts of the canopy as well as a significant aggregation on particular trees. N. quercusbaccarum showed an even more pronounced preference for particular trees and a general preference for Quercus robur over Q. petraea. In contrast to M. fagi, no vertical zonation could be detected. We think that both gall-inducing species have greater powers of dispersal than formerly assumed since they overwinter on the forest floor and yet are able to 1) gain access to the entire canopy, 2) show preference for certain host trees. We found little evidence for the phenological synchrony hypothesis proposed to explain the intertree distribution of N. quercusbaccarum. The highest density of M. fagi galls was in those parts of the canopy exposed to high solar radiation; their host choice is probably determined by micro-climatological factors. The consequences of the distribution patterns of N. quercusbaccarum and M. fagi for their ecological interactions with the host-plant, inquilines and parasitoids (e.g., canopy-layer specific performance linked to plant chemistry, density-dependent parasitism) need now to be subjected to further scientific investigation.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
474845. The spectra of general differential operators in the direct sum spaces
- Creator:
- Ibrahim, Sobhy El-sayed
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- quasi-differential expressions, essential spectra, joint field of regularity, regularly solvable operators, and direct sum spaces
- Language:
- English
- Description:
- In this paper, the general ordinary quasi-differential expression $M_p$ of $n$-th order with complex coefficients and its formal adjoint $M_p^+$ on any finite number of intervals $I_p=(a_p,b_p)$, $p=1,\dots ,N$, are considered in the setting of the direct sums of $L_{w_p}^2(a_p,b_p)$-spaces of functions defined on each of the separate intervals, and a number of results concerning the location of the point spectra and the regularity fields of general differential operators generated by such expressions are obtained. Some of these are extensions or generalizations of those in a symmetric case in [1], [14], [15], [16], [17] and of a general case with one interval in [2], [11], [12], whilst others are new.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
474846. The spectral distribution of stars magnitude 7-0 and brighter in the Henry Draper catalogue. Part I. Text and tables
- Creator:
- Seydl, Otto
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- astronomy, galactic coordinates, and distribution of stellar density
- Language:
- Czech
- Description:
- The distribution of stars of mag. 7-0 and brighter of the H. D. C. is here studied in the system of galatic co-ordinates. There are tables of numbers of stars according to both the co-ordinates for individual clases of magnitude and for all the spectral subdivisions. Also the distribution of the density of stars in longitude and latitude separately is studied for the spectral classes B, A, F, G, K, M. Finally to illustrate the distribution of stellar density according to both co-ordinates simultaneously, the maps for the classes B, A, F, G, K, M were constructed with the lines of the same density. and Text je doplněn 5 grafy hustoty hvězd (nestránkováno)
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
474847. The spectroscopic binary Xi Cygni
- Creator:
- Onderlička, B. and Handlířová, D.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- astronomy, radial velocity, and binary Xi Cygni
- Language:
- Czech
- Description:
- Radial velocity variations of the K supergiant Xi Cygnl are Investlgated on the basis of publlshed as well as new values from spectrograms In the visual and near infrared region obtalned In the period of 1977-1984 at Ondřejov, Shemakha, and Crlmea observatories. A circular orbit (P = 113.3873 days, Tmax = 2430214.33 HJD, K1 = 3,47 km/s, Vo = -20.0 km/s), still preliminary. confirms the period derlved by Parsons (1983). More accurate data are needed and the problem of the long period (Reimers 1981) should be investigated.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
474848. The spectrum of comet Arend-Roland
- Creator:
- Rajchl, J.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- spectrograms, microphotometers, and comets
- Language:
- Czech
- Description:
- Nine objective prism spectrograms by means of two cameras were achieved. It was impossible to point directly at the comet image by using the larger camera. The motions in α of both the camera and the comet were the same. The motion difference in δ was determined experimentally and introduced as correction. The photometrical tracings of the comet head and tail and of the stars were made by using a recording microphotometer. The computed dispersion curve was corrected by using the main comet head emissions. The identification of the emissions was done by a comparison with [2] and [3]. The spectrograms show strong CN and Na emissions. It was assumed, that the background below the emissions was due to continuous spectrum. Then its amplitude is nearly twice that of the emission lines. The amplitude ratio continuum/emission in the tail was 1 : 0·6. The spectrograms from the end of May show only weak C2 emissions. The tail directied towards the Sun was unobservable during our observations.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
474849. The spectrum of comet Mrkos (1957d)
- Creator:
- Ceplecha, Zd. and Rajchl, J.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- photometric tracing, microdensitometer, and comets
- Language:
- Czech
- Description:
- The study of one spectrum of comet Mrkos obtained on 1957 August 23 with an objective prism of dispersion 52 A/mm for λ 4000 A is given in this paper. and Článek doplňuje list se snímky komety (nestránkováno)
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
474850. The spiral-vortex structure of flat galaxies (prediction, theory, laboratoy and numerical experiments, observations)
- Creator:
- Afanasiev, V. L., P. V., Fridman, A. M., Ivchenko, I. N., Makov, Tu. N., Morozov, A. G., Nezlin, M. V., Pasha, I. I., Polyschenko, V. L., Rylov, A. Yu., Snezhkin, E. N., Torgashin, Yu. V., Trubnikov, A. S., and Zasov, A. V.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- space research, flat galaxies, and spiral-vortex structures
- Language:
- Czech
- Description:
- Recent observations show a dip on the rotation curve for most of spiral galaxies,Theoretically, it implies that spiral density waves must be induced by shear instabilities,Calculations prove that the observed amount of gas In galactic disks (10% for the Galaxy) is sufficient to develop the hydrodynamical Instability in gas subsystems. As surface density perturbations of shallow water and galactic gas disks are described by the same equations, experiments with shallow water rotating slmilar to galactic disks have been made, In stationary stages of rotation stationary spiral pattems occur. The number of arms depends on the profile of rotation curve, in agreement with theoretical results, Different rotation parameters lead to different structures: the circular mode, one-, two-, ... , eight-armed spirals. Branching of the spirals is observed when rotation parameters change,which suggests that the spiral branching in several galaxies comes from their non-stationary rotation. Anticyclonic vortices are observed between the arms, Azimuthal averaging of the surface density, gives a good fit for the galaxy: minlmum of before the molecular ring, for realistic profiles of shallow water rotation the spirals are trailing, But they happen to lead for opposite directions of rotation of inner and outer regions, It may explain the leading spirals in galaxies whose spin is opposite either to that oft.blose companions or to the vector of orbital momentum of the pairs. Numerical computations confirm the theoretical and experimental results.They also show a formation like a "molecular ring". Preliminary observational data agree with these results.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public