Let X=d(v,p) and Y=d(w,q) be Lorentz sequence spaces. We investigate when the space K(X,Y) of compact linear operators acting from X to Y forms or does not form an M-ideal (in the space of bounded ...linear operators). We show that K(X,Y) fails to be a non-trivial M-ideal whenever p=1 or p>q. In the case when 1>p≤q, we establish a general (essential) condition guaranteeing that K(X,Y) is not an M-ideal. In contrast, we prove that non-trivial M-ideals K(X,Y) do exist whenever 1<p<q, and we give a description of them.
Wind is the process that connects Mars' climate system. Measurements of Mars atmospheric winds from orbit would dramatically advance our understanding of Mars and help prepare for human exploration ...of the Red Planet. Multiple instrument candidates are in development and will be ready for flight in the next decade. We urge the Decadal Survey to make these measurements a priority for 2023-2032.
Clouds and aerosols play a key role in climate models, and uncertainties in the effects of clouds provide the largest error source for predicting global warming. Earth aerosols affect climate through ...direct radiative changes, aerosolcloud interactions (indirect effects), atmospheric chemistry, snow albedo, and ocean biogeochemistry (Mahowald et al., 2011). Clouds on the other planets expose us to alternate scenarios and examples of climate histories that are different from Earth (for a comparison of mesosphere clouds on Mars and Earth, see the chapter by Määttänen et al. in this volume). An early comparison of terrestrial clouds to those of Jupiter was
An initial stage in the mechanism of chemical carcinogenesis by "activated" carcinogenic polycyclic aromatic hydrocarbons is believed to involve alkylation of DNA. However, very high (atomic) ...resolution studies of alkylated DNA are not technically feasible at this time, and therefore the detailed, high-resolution three-dimensional structures of portions of alkylated DNA have been determined. The initial phase of this study (reported here) has involved the preparation of a series of adenosines and 2'-deoxyadenosines substituted at N6 by related aralkyls of differing carcinogenic potential. We report here the crystal structure determinations of four of these compounds: Compound 1, N6-(anthracenyl-9-methyl)adenosine; Compound 2, N6-(10-methyl-anthracenyl-9-methyl)adenosine; Compound 3, N6-12-methyl-benz(a)anthracenyl-7-methyladenosine; and Compound 5, N6-(10-methylanthracenyl-9-methyl)-2'-deoxyadenosine. Results are compared with those for a previously published analysis Compound 6, N6-12-methylbenz(a)anthracenyl-7-methyl-2'-deoxyadenosine. Several results of structural interest have emerged. All five compounds have the syn-conformational relationship between the sugar (ribose or 2'-deoxyribose) and the base (adenine), in contrast to the anti arrangement in B-DNA and in nonalkylated nucleosides. In four of the five compounds, there is an intramolecular hydrogen bond between the 5'-hydroxyl group and adenine. However, in the fifth molecule, this hydrogen bond is not found, and yet the conformation is syn. This indicates that formation of this internal hydrogen bond is not a prerequisite for the adoption of the syn-conformation. In general, the overall conformations of all five compounds are similar, the base lying approximately perpendicular to the polycyclic aromatic ring system. The packing of molecules in the unit cell is also of interest because it consists of alternations of adenine and polycyclic aromatic ring systems in columns through the crystal, indicating that this may serve as a model for the interaction with DNA. The oxygen atom of the sugar ring points towards the hydrocarbon ring system of another molecule. It is premature at this stage of our study to speculate as to the effects of alkylation on the conformational properties of either RNA or DNA. The only comment that appears justified is that the propensity of these adducts to adopt the syn-conformation may be indicative of a preference of alkylated DNA for the Z-conformation (even if the form that is initially attacked is B-DNA).
In the COVID-19 pandemic, children were considered to play a major role in SARS-CoV-2 transmission similar to influenza. Thus, mitigation measures have been focused on children, impacting their ...everyday life severely. Despite this, infectivity in this age group regarding SARS-CoV-2 is not yet clarified. We performed a serology study in households with confirmed SARS-CoV-2 infection to evaluate virus transmission with focus on children and adolescents. Between January and July 2021, 341 minors and 650 adults from 300 households with a confirmed index case participated in the FamilyCoviDD19-study including serological assessment for SARS-CoV-2 antibodies and a questionnaire on demographics, recent and ongoing symptoms, hygiene measures and comorbidities. 45 (16.3%) of all index cases were < 18 years old. Thereof, 55.6% reported COVID-19 associated symptoms, while nearly all adult index cases were symptomatic (94.8%). There was significantly less virus transmission by children and adolescents compared to adult index cases with a secondary attack rate of 0.29 vs. 0.54. With the caveat that the results do not necessarily apply to the Delta and Omicron variants, we conclude that children and adolescents are less susceptible for SARS-CoV-2 infection, more frequently show an asymptomatic course of disease and are less infective than adults.
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