22,537 research outputs found
Molecular gyroscopes and biological effects of weak ELF magnetic fields
Extremely-low-frequency magnetic fields are known to affect biological
systems. In many cases, biological effects display `windows' in biologically
effective parameters of the magnetic fields: most dramatic is the fact that
relatively intense magnetic fields sometimes do not cause appreciable effect,
while smaller fields of the order of 10--100 T do. Linear resonant
physical processes do not explain frequency windows in this case. Amplitude
window phenomena suggest a nonlinear physical mechanism. Such a nonlinear
mechanism has been proposed recently to explain those `windows'. It considers
quantum-interference effects on protein-bound substrate ions. Magnetic fields
cause an interference of ion quantum states and change the probability of
ion-protein dissociation. This ion-interference mechanism predicts specific
magnetic-field frequency and amplitude windows within which biological effects
occur. It agrees with a lot of experiments. However, according to the
mechanism, the lifetime of ion quantum states within a protein
cavity should be of unrealistic value, more than 0.01 s for frequency band
10--100 Hz. In this paper, a biophysical mechanism has been proposed that (i)
retains the attractive features of the ion interference mechanism and (ii) uses
the principles of gyroscopic motion and removes the necessity to postulate
large lifetimes. The mechanism considers dynamics of the density matrix of the
molecular groups, which are attached to the walls of protein cavities by two
covalent bonds, i.e., molecular gyroscopes. Numerical computations have shown
almost free rotations of the molecular gyros. The relaxation time due to van
der Waals forces was about 0.01 s for the cavity size of 28 angstr\"{o}ms.Comment: 10 pages, 7 figure
The influence of the thyroid gland and ambient temperatures on fertility of rams
Digitized 2007 AES.Includes bibliographical references (pages 73-78)
Dynamical structure factor of a nonlinear Klein-Gordon lattice
The quantum modes of a nonlinear Klein-Gordon lattice have been computed
numerically [L. Proville, Phys. Rev. B 71, 104306 (2005)]. The on-site
nonlinearity has been found to lead to phonon bound states. In the present
paper, we compute numerically the dynamical structure factor so as to simulate
the coherent scattering cross section at low temperature. The inelastic
contribution is studied as a function of the on-site anharmonicity.
Interestingly, our numerical method is not limited to the weak anharmonicity
and permits one to study thoroughly the spectra of nonlinear phonons
Practical tests with anthelmintics for grazing lambs
The bulletin is a report on University of Missouri Agricultural Experiment Station research project 142, 'Sheep Production'--P. [3].Digitized 2007 AES.Includes bibliographical references (page 16)
ΦCrAss001 represents the most abundant bacteriophage family in the human gut and infects Bacteroides intestinalis
peer-reviewedCrAssphages are an extensive and ubiquitous family of tailed bacteriophages, predicted to infect bacteria of the order Bacteroidales. Despite being found in ~50% of individuals and representing up to 90% of human gut viromes, members of this viral family have never been isolated in culture and remain understudied. Here, we report the isolation of a CrAssphage (ΦCrAss001) from human faecal material. This bacteriophage infects the human gut symbiont Bacteroides intestinalis, confirming previous in silico predictions of the likely host. DNA sequencing demonstrates that the bacteriophage genome is circular, 102 kb in size, and has unusual structural traits. In addition, electron microscopy confirms that ΦcrAss001 has a podovirus-like morphology. Despite the absence of obvious lysogeny genes, ΦcrAss001 replicates in a way that does not disrupt proliferation of the host bacterium, and is able to maintain itself in continuous host culture during several weeks
A catalogue of the collections of Mexican amber at the Natural History Museum, London and National Museums Scotland, Edinburgh, UK
A catalogue is here provided of the pieces of Mexican amber with inclusions in the collections of the Natural History Museum, London, and National Museums Scotland, Edinburgh, both in the United Kingdom. There are 32 pieces in the Natural History Museum and 101 pieces in National Museums Scotland which contain a combined total of 557 arthropod and 13 plant inclusions. Four orders and 11 families of arthropods are additional to a taxonomic list of Mexican amber arthropods published in 2010
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