A Physical Limit to the Magnetic Fields of T Tauri Stars

Recent estimates of magnetic field strengths in T Tauri stars yield values $B=1$--$4\,{\rm kG}$. In this paper, I present an upper limit to the photospheric values of $B$ by computing the equipartition values for different surface gravities and effective temperatures. The values of $B$ 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