13 research outputs found
Magnetic Field Measurement with Ground State Alignment
Observational studies of magnetic fields are crucial. We introduce a process
"ground state alignment" as a new way to determine the magnetic field direction
in diffuse medium. The alignment is due to anisotropic radiation impinging on
the atom/ion. The consequence of the process is the polarization of spectral
lines resulting from scattering and absorption from aligned atomic/ionic
species with fine or hyperfine structure. The magnetic field induces precession
and realign the atom/ion and therefore the polarization of the emitted or
absorbed radiation reflects the direction of the magnetic field. The atoms get
aligned at their low levels and, as the life-time of the atoms/ions we deal
with is long, the alignment induced by anisotropic radiation is susceptible to
extremely weak magnetic fields (G). In fact,
the effects of atomic/ionic alignment were studied in the laboratory decades
ago, mostly in relation to the maser research. Recently, the atomic effect has
been already detected in observations from circumstellar medium and this is a
harbinger of future extensive magnetic field studies. A unique feature of the
atomic realignment is that they can reveal the 3D orientation of magnetic
field. In this article, we shall review the basic physical processes involved
in atomic realignment. We shall also discuss its applications to
interplanetary, circumstellar and interstellar magnetic fields. In addition,
our research reveals that the polarization of the radiation arising from the
transitions between fine and hyperfine states of the ground level can provide a
unique diagnostics of magnetic fields in the Epoch of Reionization.Comment: 30 pages, 12 figures, chapter in Lecture Notes in Physics "Magnetic
Fields in Diffuse Media". arXiv admin note: substantial text overlap with
arXiv:1203.557
Speciation and sources of toxic metals in sediments of Lake Chapala, Mexico
Heavy metals chemical speciation in Lake Chapala sediments was studied using sequential extraction to assess the mobility of potentially biotoxic metals and to elucidate their sources. Lake water quality was also studied. Results show Cd, Pb, Cr present in exchangeable and carbonate fractions indicating anthropogenic origin. An ecologic history indicates anthropogenic sources of Cd, Pb, Cr during 1960-2006. Risk Assessment Code indicates very high risk of pollution for water column due to high potential detachment of heavy metals. © 2010, Sociedad Química de México
Speciation and sources of toxic metals in sediments of Lake Chapala, Mexico
Heavy metals chemical speciation in Lake Chapala sediments was studied using sequential extraction to assess the mobility of potentially biotoxic metals and to elucidate their sources. Lake water quality was also studied. Results show Cd, Pb, Cr present in exchangeable and carbonate fractions indicating anthropogenic origin. An ecologic history indicates anthropogenic sources of Cd, Pb, Cr during 1960-2006. Risk Assessment Code indicates very high risk of pollution for water column due to high potential detachment of heavy metals. © 2010, Sociedad Química de México
Ulcerative colitis and sarcoidosis.
Ulcerative colitis is not commonly associated with recognizable pulmonary disease and only four sporadic cases of sarcoidosis in association with ulcerative colitis have been previously reported. However, in a series of 680 patients with ulcerative colitis, pulmonary or extra-pulmonary sarcoidosis has at some stage been present in eight. These cases are reported in detail. The onset of either condition bore no relationship to the activity or the presence of recognized peripheral manifestations of the other, suggesting that the two diseases were independent. However, three of the patients had the HLA B8 DR3 phenotype which is a higher prevalence than seen in previous studies of either disease alone. Patients with ulcerative colitis who possess this HLA phenotype may possibly be more susceptible to developing sarcoidosis
Lipolytic enzymes and hydrolytic rancidity
Lipolysis, the enzymic hydrolysis of milk lipids to free fatty acids and partial glycerides, is a constant concern to the dairy industry because of the detrimental effcts it can have on the flvor and other properties of milk and milk products. However, free fatty acids also contribute to the desirable flavor of milk and milk products when present at low concentrations and, in some cheeses, when present at high concentrations. The enzymes responsible for the detrimental effects of lipolysis are of two main types: those indigenous to milk, and those of microbial origin. The major indigenous milk enzyme is lipoprotein lipase. It is active on the fat in natural milk fat globules only after their disruption by physical treatments or if certain blood serum lipoproteins are present. The major microbial lipases are produced by psychrotrophic bacteria. Many of these enzymes are heat stable and are particularly significant in stored products. Human milk differs from cows' milk in that it contains two lipases, a lipoprotein lipase and a bile salt-stimulated lipase. The ability of the latter to cause considerable hydrolysis of ingested milk lipids has important nutritional implications