1,223 research outputs found
In Remembrance of Doomed Youth: Private Ralph C. Crew (1893–1917), 87th Battalion, Grenadier Guards, Canadian Expeditionary Force
A contribution to the study of sex-determination in the anura
The problem of sex -determination possesses
a peculiar fascination for the student of. animate
Nature and the fact that it remains as yet unsolved,
permits one to set out on the great adventure of its
solution with high hopes and, if one is young, with
confidence.But with the experience of the difficulties
and complexities of the subject comes a chastened
mind, and at the journey's end one is left with just
the hope that in the results of the work which has
enslaved by its all -absorbing fascination, there may
be found some suggestion as to the direction in which
the truth of the matter really lies.In this study the question of sex- determination is approached through a consideration of the abnormalities of the reproductive system which have
been recorded in Zoological literature. Often an
appreciation of the abnormal can illumine the mechanism of the normal.The typical sexual characters are first
briefly described, so as to furnish standards to
which the abnormalities may be referred. The abnormalities are then tabulated and analysed. A
brief consideration of the embryology of the reproductive system naturally follows and the investigation is brought to a close by a review of what is
known of the sex-ratio. An account is given of certain experiments.It is intended to demonstrate that the abnormalities obviously suggest that in the case of the
frog, sex is not irreversible; that the facts of embryology lend support to this view; and that a .study of
the variations of the sex -ratio supplies conclusive
proof that sax- reversal can and does occur. The graduated degrees of abnormality as portrayed, are shown . to provide a clear view of the process by which sex-reversal is effected
Black-Footed Ferret Recovery
The captive population of black-footed ferrets increased from 24 to 58 animals in 1988, and was split to provide the species added protection against extinction. Experimental reintroductions may begin in 1991. In some areas, experimental population designations as authorized under Section 10 (j) of the Endangered Species Act may be used to provide wider management latitude. The Black-footed Ferret Interstate Coordinating Committee oversees much of the work related to reintroduction. Expanded effort to locate wild ferrets now includes a $10,000 reward offer. Research focuses on captive breeding, reintroduction techniques, disease, and habitat. A new Recovery Plan was approved in 1988
Black-Footed Ferret Recovery
The captive population of black-footed ferrets increased from 24 to 58 animals in 1988, and was split to provide the species added protection against extinction. Experimental reintroductions may begin in 1991. In some areas, experimental population designations as authorized under Section 10 (j) of the Endangered Species Act may be used to provide wider management latitude. The Black-footed Ferret Interstate Coordinating Committee oversees much of the work related to reintroduction. Expanded effort to locate wild ferrets now includes a $10,000 reward offer. Research focuses on captive breeding, reintroduction techniques, disease, and habitat. A new Recovery Plan was approved in 1988
Welfare to Web to Work: Internet Job Searching Among Former Welfare Clients in Florida
This study provides the first empirical test of whether searching for jobs on the Internet can help people gain access to high quality jobs. Using new data from former welfare clients in Florida, we present results from a multivariate regression analysis of Internet job searching on wages and on a number of job benefits. On average, Internet job searchers receive better jobs than people who conducted more traditional job searches, net of numerous control variables. These findings suggest that welfare recipients have a great deal to gain from searching for their jobs on the Internet
Why the extensive use of executive orders by state governors may not be a threat to democracy
Like the president, state Governors frequently make use of executive orders in order to pursue their agendas. But do these unilateral actions undermine democracy? No, argue Alexandra G. Cockerham and Robert E. Crew, Jr, who find that legislatures can be willing to delegate policy-making authority to governors if they are of the same party or if the legislature is fragmented
The Covid-19 pandemic shows the power and limits of American federalism
While there has been a great deal of attention paid to how President Trump has responded to the Covid-19 pandemic, Alexandra Cockerham and Robert E. Crew Jr. argue that, to get a true sense of the country’s response, we should look at the actions of state governors and mayors within states. While the federal government has tried to coordinate some efforts, federalism has meant that governors and local administrators have been able to adapt their responses, with the hardest hit states like New York setting a precedent for others
The Physics of Miniature Worlds
This excerpt from a book length work on the history of the methodology of experimental physical models (physically similar systems) interwoven in Ludwig Wittgenstein's life begins in 1913-1914. It also discusses works by physicists around the same time that were thematically related to the philosophical topics he was working on: Ludwig Boltzmann, Wilhelm Ostwald, Edgar Buckingham, James Thomson, D'Arcy Wentworth Thompson, Henry Crew (and his new translation of Galileo's Two New Sciences during this period), Heike Kamerlingh Onnes, Van Der Waals, and Rayleigh (following up on the work of Gabriel Stokes), and Richard C Tolman. The landmark work at Britain's National Physical Laboratory in 1914 on Similar Motions by Stanton and Pannell, following up on Osborne Reynolds' work in Manchester, is also described and discussed.
Connections between physics and the history of flight are mentioned, too: Penuad's successes, Boltzmann's relationship with engineer Otto Lilienthal, and the significance that Hermann von Helmholtz's landmark paper in meteorology which addressed the problem of steering aircraft, took on during this period
Precision Pointing of IBEX-Lo Observations
Post-launch boresight of the IBEX-Lo instrument onboard the Interstellar
Boundary Explorer (IBEX) is determined based on IBEX-Lo Star Sensor
observations. Accurate information on the boresight of the neutral gas camera
is essential for precise determination of interstellar gas flow parameters.
Utilizing spin-phase information from the spacecraft attitude control system
(ACS), positions of stars observed by the Star Sensor during two years of IBEX
measurements were analyzed and compared with positions obtained from a star
catalog. No statistically significant differences were observed beyond those
expected from the pre-launch uncertainty in the Star Sensor mounting. Based on
the star observations and their positions in the spacecraft reference system,
pointing of the IBEX satellite spin axis was determined and compared with the
pointing obtained from the ACS. Again, no statistically significant deviations
were observed. We conclude that no systematic correction for boresight geometry
is needed in the analysis of IBEX-Lo observations to determine neutral
interstellar gas flow properties. A stack-up of uncertainties in attitude
knowledge shows that the instantaneous IBEX-Lo pointing is determined to within
\sim 0.1\degr in both spin angle and elevation using either the Star Sensor
or the ACS. Further, the Star Sensor can be used to independently determine the
spacecraft spin axis. Thus, Star Sensor data can be used reliably to correct
the spin phase when the Star Tracker (used by the ACS) is disabled by bright
objects in its field-of-view. The Star Sensor can also determine the spin axis
during most orbits and thus provides redundancy for the Star Tracker.Comment: 22 pages, 18 figure
Intensity of Brillouin light scattering from spin waves in magnetic multilayers with noncollinear spin configurations: Theory and experiment
The scattering of photons from spin waves (Brillouin light scattering -- BLS)
is a well-established technique for the study of layered magnetic systems. The
information about the magnetic state and properties of the sample is contained
in the frequency position, width, and intensity of the BLS peaks. Previously
[Phys. Rev. B 67, 184404 (2003)], we have shown that spin wave frequencies can
be conveniently calculated within the ultrathin film approach, treating the
intralayer exchange as an effective bilinear interlayer coupling between thin
virtual sheets of the ferromagnetic layers. Here we give the consequent
extension of this approach to the calculation of the Brillouin light scattering
(BLS) peak intensities. Given the very close relation of the BLS cross-section
to the magneto-optic Kerr effect (MOKE), the depth-resolved longitudinal and
polar MOKE coefficients calculated numerically via the usual magneto-optic
formalism can be employed in combination with the spin wave precessional
amplitudes to calculate full BLS spectra for a given magnetic system. This
approach allows an easy calculation of BLS intensities even for noncollinear
spin configurations including the exchange modes. The formalism is applied to a
Fe/Cr/Fe/Ag/Fe trilayer system with one antiferromagnetically coupling spacer
(Cr). Good agreement with the experimental spectra is found for a wide variety
of spin configurations.Comment: 19 pages, 5 figure
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