906 research outputs found
Frequency spectra of the sources 3C 295 and 3C 380
Interferometric flux density measurements on stellar light source
The catalogue of the discrete sources in the declination range from -13 deg to -2 deg
The results of the discrete source measurements with declinations -13 deg or = delta or = -2 deg and right ascensions 0 sub h + 24 sub h are given and were obtained as part of the systematic decametric survey of the celestial sphere with the rotatiotelecope UTR-2. Three hundred sixteen sources were found in the given declination range, four of which were observed for the first time. The source coordinates measured in the survey were compared with those from the 4th Cambridge survey at 178 MHz and the Parkes survey at 408 MHz
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A Hypothesis to Explain Cancers in Confined Colonies of Naked Mole Rats
Abstract: Naked mole rats (NMRs) are subterranean eusocial mammals, known for their virtual absence of aging in their first 20 to 30 years of life, and their apparent resistance to cancer development. As such, this species has become an important biological model for investigating the physiological and molecular mechanisms behind cancer resistance. Two recent studies have discovered middle and late-aged worker (that is, non-breeding) NMRs in captive populations exhibiting neoplasms, consistent with cancer development, challenging the claim that NMRs are cancer resistant. These cases are possibly artefacts of inbreeding or certain rearing conditions in captivity, but they are also consistent with evolutionary theory.We present field data showing that worker NMRs live on average for 1 to 2 years. This, together with considerable knowledge about the biology of this species, provides the basis for an evolutionary explanation for why debilitating cancers in NMRs should be rare in captive populations and absent in the wild. Whereas workers are important for maintaining tunnels, colony defence, brood care, and foraging, they are highly vulnerable to predation. However, surviving workers either replace dead breeders, or assume other less active functions whilst preparing for possible dispersal. These countervailing forces (selection resulting in aging due to early-life investments in worker function, and selection for breeder longevity) along with the fact that all breeders derive from the worker morph, can explain the low levels of cancer observed by these recent studies in captive colonies. Because workers in the field typically never reach ages where cancer becomes a risk to performance or mortality, those rare observations of neoplastic growth should be confined to the artificial environments where workers survive to ages rarely if ever occurring in the wild. Thus, we predict that the worker phenotype fortuitously benefits from anti-aging and cancer protection in captive populations
An Independent Derivation of the Oxford Jet Kinetic Luminosity Formula
This letter presents a theoretical derivation of an estimate for a radio
source jet kinetic luminosity. The expression yields jet powers that are
quantitatively similar to a more sophisticated empirical relation published by
the Willott, Blundell and Rawlings at Oxford. The formula allows one to
estimate the jet kinetic luminosity from the measurement of the optically thin
radio lobe emission in quasars and radio galaxies. Motivated by recent X-ray
observation, the derivation assumes that most of the energy in the lobes is in
plasma thermal energy with a negligible contribution from magnetic energy (not
equipartition). The close agreement of the two independent expressions makes
the veracity of these estimates seem very plausible.Comment: To appear in ApJ Letter
Lingual Ischemia from Prolonged Insertion of a Fastrach Laryngeal Mask Airway
We report a case of lingual ischemia and swelling in an elderly stroke patient from prolonged insertion of a FastrachTM Laryngeal Mask Airway ® following a failed Emergency Department intubation. Simple suggestions to mitigate such injury are provided
RC J1148+0455 identification: gravitational lens or group of galaxies ?
The structure of the radio source RC B1146+052 of the ``Cold'' catalogue is
investigated by data of the MIT-GB-VLA survey at 4850 MHz. This source belongs
to the steep spectrum radio sources subsample of the RC catalogue. Its spectral
index is = -1.04. The optical image of this source obtained with 6m
telescope is analysed. The radio source center is situated in a group of 8
galaxies of about 24 in the R-filter. The possible explanations of the
complex structure of radio components are considered.Comment: 6 pages, 5 figures, uses psfig.sty. This was the poster as presented
on Gamow Memorial Internat. Conference GMIC'99 "Early Universe: Cosmological
Problems and Instrumental Technologies" in St.Petersburg, 23-27 Aug., 1999.
Submitted to Proceedings to be published in A&A Transaction
Resumption of elective colorectal surgery during COVID-19 and risk of death
Peer reviewedPostprin
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