1,429 research outputs found
Effects of varying management levels of crops and livestock on optimal farm organizations
"Publication authorized July 17, 1964.
Insulation from Liability through Subsidiary Corporations
While the desire for limited liability has played its part in
increasing the use of the corporate device among the smaller industrial
units, it alone is not responsible for such extensive use
of the corporation arpong the larger industrial units. A primary
factor there has been absentee ownership, attendant on the wide
distribution of securities. The corporate device has lent itself
peculiarly well to the public marketing of securities and to the
evolution of a management structure in which the so-called
owners play insignificant roles. The factor of limited liability
has not been unimportant. It merely has not been paramount.,
The same can be said for the evolution that has taken place
within the business units using the corporate form. Recent
years especially have seen an increasing use of the subsidiaryparent
structure. The farthest point along this line of evolution
has been reached in the public utility field. But other businesses
have adopted it and used it extensively. The reasons for the
use of this structure are manifold. The increased facility in
financing; the desire to escape the difficulty, if not the impossibility,
of qualifying the parent company as a foreign corporation
in a particular state; the avoidance of complicatinn.- involved
in the purchase of physical assets: the raention of the
good will of an established business unit; the avoidance of taxation;
the avoidance of cumbersome management structures; the
deb.. for limited liability, are among the primary motives.
The desire for limited liability has been merely one among many
factors. And at times it has appeared to recede
Could the Pioneer anomaly have a gravitational origin?
If the Pioneer anomaly has a gravitational origin, it would, according to the
equivalence principle, distort the motions of the planets in the Solar System.
Since no anomalous motion of the planets has been detected, it is generally
believed that the Pioneer anomaly can not originate from a gravitational source
in the Solar System. However, this conclusion becomes less obvious when
considering models that either imply modifications to gravity at long range or
gravitational sources localized to the outer Solar System, given the
uncertainty in the orbital parameters of the outer planets. Following the
general assumption that the Pioneer spacecraft move geodesically in a
spherically symmetric spacetime metric, we derive the metric disturbance that
is needed in order to account for the Pioneer anomaly. We then analyze the
residual effects on the astronomical observables of the three outer planets
that would arise from this metric disturbance, given an arbitrary metric theory
of gravity. Providing a method for comparing the computed residuals with actual
residuals, our results imply that the presence of a perturbation to the
gravitational field necessary to induce the Pioneer anomaly is in conflict with
available data for the planets Uranus and Pluto, but not for Neptune. We
therefore conclude that the motion of the Pioneer spacecraft must be
non-geodesic. Since our results are model independent within the class of
metric theories of gravity, they can be applied to rule out any model of the
Pioneer anomaly that implies that the Pioneer spacecraft move geodesically in a
perturbed spacetime metric, regardless of the origin of this metric
disturbance.Comment: 16 pages, 6 figures. Rev. 3: Major revision. Accepted for publication
in Phys. Rev. D. Rev. 4: Added two reference
Metric of a tidally perturbed spinning black hole
We explicitly construct the metric of a Kerr black hole that is tidally
perturbed by the external universe in the slow-motion approximation. This
approximation assumes that the external universe changes slowly relative to the
rotation rate of the hole, thus allowing the parameterization of the
Newman-Penrose scalar by time-dependent electric and magnetic tidal
tensors. This approximation, however, does not constrain how big the spin of
the background hole can be and, in principle, the perturbed metric can model
rapidly spinning holes. We first generate a potential by acting with a
differential operator on . From this potential we arrive at the metric
perturbation by use of the Chrzanowski procedure in the ingoing radiation
gauge. We provide explicit analytic formulae for this metric perturbation in
spherical Kerr-Schild coordinates, where the perturbation is finite at the
horizon. This perturbation is parametrized by the mass and Kerr spin parameter
of the background hole together with the electric and magnetic tidal tensors
that describe the time evolution of the perturbation produced by the external
universe. In order to take the metric accurate far away from the hole, these
tidal tensors should be determined by asymptotically matching this metric to
another one valid far from the hole. The tidally perturbed metric constructed
here could be useful in initial data constructions to describe the metric near
the horizons of a binary system of spinning holes. This perturbed metric could
also be used to construct waveforms and study the absorption of mass and
angular momentum by a Kerr black hole when external processes generate
gravitational radiation.Comment: 17 pages, 3 figures. Final PRD version, minor typos, etc corrected.
v3: corrected typo in Eq. (35) and (57
Invasive Streptococcus pneumoniae in Children, Malawi, 2004–2006
Of 176 invasive Streptococcus pneumoniae isolates from children in Malawi, common serotypes were 1 (23%), 6A/B (18%), 14 (6%), and 23F (6%). Coverage with the 7-valent pneumococcal conjugate vaccine (PCV) was 39%; PCV10 and PCV13 increased coverage to 66% and 88%, respectively. We found chloramphenicol resistance in 27% of isolates and penicillin nonsusceptibility in 10% (by using meningitis breakpoints); all were ceftriaxone susceptible
Self Interacting Dark Matter in the Solar System
Weakly coupled, almost massless, spin 0 particles have been predicted by many
extensions of the standard model of particle physics. Recently, the PVLAS group
observed a rotation of polarization of electromagnetic waves in vacuum in the
presence of transverse magnetic field. This phenomenon is best explained by the
existence of a weakly coupled light pseudoscalar particle. However, the
coupling required by this experiment is much larger than the conventional
astrophysical limits. Here we consider a hypothetical self-interacting
pseudoscalar particle which couples weakly with visible matter.
Assuming that these pseudoscalars pervade the galaxy, we show that the solar
limits on the pseudoscalar-photon coupling can be evaded.Comment: 17 pages, 2 figure
Comparison of Binax NOW urine antigen test and pneumococcal DNA assay using qPCR before and after nasopharyngeal swabbing in healthy Malawian children.
Diagnosis of invasive pneumococcal disease is challenging. We compared Binax NOW pneumococcal urinary antigen test with blood pneumococcal PCR in healthy Malawian children with and without pneumococcal carriage, and we found a high false-positive rate with Binax NOW. Blood pneumococcal PCR positivity was 66/88 (75%) compared to 5/27 (18%) when nasopharyngeal swabbing was performed first compared to after blood sampling for pneumococcal blood PCR. We speculate that nasopharyngeal swabbing may be causing a breach of mucosal integrity, leading to invasion into the bloodstream. These findings need to be confirmed with autolysin-based PCR assays
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