7,083 research outputs found
A Physical Limit to the Magnetic Fields of T Tauri Stars
Recent estimates of magnetic field strengths in T Tauri stars yield values
--. In this paper, I present an upper limit to the
photospheric values of by computing the equipartition values for different
surface gravities and effective temperatures. The values of derived from
the observations exceed this limit, and I examine the possible causes for this
discrepancy
Pulmonary tuberculosis in East African native troops
This is not a record of a planned research
carried out as a whole time occupation: it is the
record of investigations made, during a tour of duty
as a Medical Specialist in the Royal Army Medical
Corps in East Africa Command, in an attempt to answer certain questions which forced themselves upon my notice.
The literature dealing with Tuberculosis in
East African natives is scanty and with one or two
exceptions pessimistic. It was the realization than
this pessimism was not entirely justified that gave
the initial stimulus to these investigations.
Critical revision of t he case notes has revealed two major deficiencies: the routine investigations were not always made as regularly as they
should have been and in some cases the treatment
given was ill-advised. The irregularity of the
routine investigations was due to pressure of other
more urgent work. During the period in question
there were two major outbreaks of Falciparum Malari
and an epidemic of Typhoid Fever. During these outbreaks so much additional work was thrown upon the laboratory staff that routine investigations on
chronic cases had to be deferred. The errors in
treatment were due to ignorance on my part - an
ignorance which it Was the main purpose of this
investigation to rectify.
East African Natives suffering from Pulmonary
Tuberculosis can obtain specialist treatment at three centres: Kibongoto Sanatorium, Tanganyika Territory; the Hospital f or Chest Diseases, Mombasa, Kenya: and
Mulago Hospital, Kampala, Uganda. I was able to visit each of these hospitals and it was encouraging to find that a reasonable optimism prevailed at them all.
No account of these investigations would be
complete without acknowledgement of the help so freely
given to me on all sides. The East African native
dislikes lying in bed. The Nursing Officers of Queen
Alexandra's Royal Army Nursing Corps, who were in
charge of the Tuberculosis wards, were indefatigable
in their efforts to enforce strict rest in bed
Hydrogen Two-Photon Continuum Emission from the Horseshoe Filament in NGC 1275
Far ultraviolet emission has been detected from a knot of Halpha emission in
the Horseshoe filament, far out in the NGC 1275 nebula. The flux detected
relative to the brightness of the Halpha line in the same spatial region is
very close to that expected from Hydrogen two-photon continuum emission in the
particle heating model of Ferland et al. (2009) if reddening internal to the
filaments is taken into account. We find no need to invoke other sources of far
ultraviolet emission such as hot stars or emission lines from CIV in
intermediate temperature gas to explain these data.Comment: 9 pages, 8 figures. Accepted for publication in MNRA
Cyanobacteria blooms cannot be controlled by effective microorganisms (EM) from mud- or Bokashi-balls
In controlled experiments, the ability of ‘‘Effective Microorganisms (EM, in the form of mudballs or Bokashi-balls)’’ was tested for clearing waters from cyanobacteria. We found suspensions of EM-mudballs up to 1 g l-1 to be ineffective in reducing cyanobacterial growth. In all controls and EM-mudball treatments up to 1 g l-1 the cyanobacterial chlorophyll-a (Chl-a) concentrations increased within 4 weeks from&120 to 325–435 lg l-1. When pieces of EM-mudballs (42.5 g) were added to 25-l lake water with cyanobacteria, no decrease of cyanobacteria as compared to untreated controls was observed. In contrast, after 4 weeks cyanobacterial Chl-a concentrations were significantly higher in EM-mudball treatments (52 lg l-1) than in controls (20 lg l-1). Only when suspensions with extremely high EM-mudball concentrations were applied (i.e., 5 and 10 g l-1), exceeding the recommended concentrations by orders of magnitude, cyanobacterial growth was inhibited and a bloom forming concentration was reduced strongly. In these high dosing treatments, the oxygen concentration dropped initially to very low levels of 1.8 g l-1. This was most probably through forcing strong light limitation on the cyanobacteria caused by the high amount of clay and subsequent high turbidity of the water. Hence, this study yields no support for the hypothesis that EM is effective in preventing cyanobacterial proliferation or in terminating blooms. We consider EM products to be ineffective because they neither permanently bind nor remove phosphorus from eutroficated systems, they have no inhibiting effect on cyanobacteria, and they could even be an extra source of nutrients
A Critique of Current Magnetic-Accretion Models for Classical T-Tauri Stars
Current magnetic-accretion models for classical T-Tauri stars rely on a
strong, dipolar magnetic field of stellar origin to funnel the disk material
onto the star, and assume a steady-state. In this paper, I critically examine
the physical basis of these models in light of the observational evidence and
our knowledge of magnetic fields in low-mass stars, and find it lacking.
I also argue that magnetic accretion onto these stars is inherently a
time-dependent problem, and that a steady-state is not warranted.
Finally, directions for future work towards fully-consistent models are
pointed out.Comment: 2 figure
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