36,634 research outputs found
Application of dimensional analysis and group theory to the solution of ordinary and partial differential equations Final report, 17 Jan. 1966 - 16 Jan. 1967
Dimensional analysis and group theory methods of solving ordinary and partial differential equation
Experimental evidence for kin-biased helping in a cooperatively breeding vertebrate
The widespread belief that kin selection is necessary for the evolution of cooperative breeding in vertebrates has recently been questioned. These doubts have primarily arisen because of the paucity of unequivocal evidence for kin preferences in cooperative behaviour. Using the cooperative breeding system of long-tailed tits (Aegithalos caudatus) in which kin and non-kin breed within each social unit and helpers are failed breeders, we investigated whether helpers preferentially direct their care towards kin following breeding failure. First, using observational data, we show that not all failed breeders actually become helpers, but that those that do help usually do so at the nest of a close relative. Second, we confirm the importance of kinship for helping in this species by conducting a choice experiment. We show that potential helpers do not become helpers in the absence of close kin and, when given a choice between helping equidistant broods belonging to kin and non-kin within the same social unit, virtually all helped at the nest of kin. This study provides strong evidence that kinship plays an essential role in the maintenance of cooperative breeding in this species
Application of the scalar and vector potentials to the aerodynamics of jets
The applicability of a method based on the Stokes potentials (vector and scalar potentials) to computations associated with the aerodynamics of jets was examined. The aerodynamic field near the nozzle could be represented and that the influence of a nonuniform velocity profile at the nozzle exit plane could be determined. Also computations were made for an axisymmetric jet exhausting into a quiescient atmosphere. The velocity at the axis of the jet, and the location of the half-velocity points along the jet yield accurate aerodynamic field computations. Inconsistencies among the different theoretical characterizations of jet flowfields are shown
Alternator and voltage regulator-exciter for a Brayton cycle space power system. Volume 2 - Unbalanced electromagnetic forces
Unbalanced electromagnetic forces in Brayton cycle turboalternator for space power syste
A Mathematical Model for Estimating Biological Damage Caused by Radiation
We propose a mathematical model for estimating biological damage caused by
low-dose irradiation. We understand that the Linear Non Threshold (LNT)
hypothesis is realized only in the case of no recovery effects. In order to
treat the realistic living objects, our model takes into account various types
of recovery as well as proliferation mechanism, which may change the resultant
damage, especially for the case of lower dose rate irradiation. It turns out
that the lower the radiation dose rate, the safer the irradiated system of
living object (which is called symbolically "tissue" hereafter) can have
chances to survive, which can reproduce the so-called dose and dose-rate
effectiveness factor (DDREF).Comment: 22 pages, 6 Figs, accepted in Journal of the Physical Society of
Japa
Direct dialling of Haar random unitary matrices
Random unitary matrices find a number of applications in quantum information
science, and are central to the recently defined boson sampling algorithm for
photons in linear optics. We describe an operationally simple method to
directly implement Haar random unitary matrices in optical circuits, with no
requirement for prior or explicit matrix calculations. Our physically-motivated
and compact representation directly maps independent probability density
functions for parameters in Haar random unitary matrices, to optical circuit
components. We go on to extend the results to the case of random unitaries for
qubits
Are Recent Peculiar Velocity Surveys Consistent?
We compare the bulk flow of the SMAC sample to the predictions of popular
cosmological models and to other recent large-scale peculiar velocity surveys.
Both analyses account for aliasing of small-scale power due to the sparse and
non-uniform sampling of the surveys. We conclude that the SMAC bulk flow is in
marginal conflict with flat COBE-normalized Lambda-CDM models which fit the
cluster abundance constraint. However, power spectra which are steeper
shortward of the peak are consistent with all of the above constraints. When
recent large-scale peculiar velocity surveys are compared, we conclude that all
measured bulk flows (with the possible exception of that of Lauer & Postman)
are consistent with each other given the errors, provided the latter allow for
`cosmic covariance'. A rough estimate of the mean bulk flow of all surveys
(except Lauer & Postman) is ~400 km/s towards l=270, b=0.Comment: 8 pages, 3 figures. To appear in Proceedings of the Cosmic Flows
Workshop, Victoria, B. C., Canada, July 1999, eds. S. Courteau, M. Strauss,
and J. Willic
Symptomatic adrenal insufficiency during inhaled corticosteroid treatment
Symptomatic adrenal insufficiency, presenting
as hypoglycaemia or poor weight
gain, may occur on withdrawal of corticosteroid
treatment but has not previously
been reported during inhaled corticosteroid
treatment. This case series illustrates
the occurence of clinically
significant adrenal insufficiency in asthmatic
children while patients were on
inhaled corticosteroid treatment and the
unexpected modes of presentation. General
practitioners and paediatricians need
to be aware that this unusual but acute
serious complication may occur in patients
treated
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